Archive for the ‘Stell Cell Research’ Category

Pathways to Stem Cell Science | Pluripotent Stem Cell …

Stell Cell Research | Posted by admin
May 14 2019

Interested in a stem cell career but lack the relevant hands-on skills? Already working with stem cells but experiencing problems your mentor can't solve? Want to expand your skill set and appeal to future employers by learning widely sought-after stem cell techniques? Pathways to Stem Cell Science's Pluripotent Stem Cell Techniques Course is the program for you!

What are human pluripotent stem cells (hPSCs) and why should college students learn to work with them? hPSCs are unique and widely used cells with the capacity to generate any type of cell in the adult human body. They can be isolated from any person and are employed extensively throughout the world in a variety of down-stream applications from research, to therapeutics to diagnostic testing. hPSCs are extremely difficult to grow and manipulate, even for experienced scientists with prior stem cell experience. They can only be handled following extensive training by stem cell experts, like the scientists at Pathways to Stem Cell Science. hPSC culture is an is an advanced 21st century skill that very few college students acquire. Professional training in cutting edge techniques like stem cell culture, can help college students to build their resumes and stand out to future employers.

Originally developed in 2009 at the USC Stem Cell Core, the Pluripotent Stem Cell Techniques Course at Pathways to Stem Cell Science, provides comprehensive training in validated techniques for culturing, freezing and manipulating hPSCs. Our well-established five-day course has helped hundreds of students to gain advanced stem cell skills for laboratory positions in college and professional employment. Participating students learn optimized techniques for culturing human embryonic and induced pluripotent stem cells, following streamlined protocols designed to plug into any hPSC program. We also provide guidance with laboratory set up and regulatory compliance in addition to ongoing support troubleshooting problems once you are working in a stem cell laboratory.

Apply today and gain comprehensive personalized training in advanced stem cell methods taught by academic and industry experts.

Important note: The hPSC workshop provides advanced training in complex stem cell techniques. To attend this course, you must have prior experience culturing mammalian cells using aseptic technique in a professional cell culture setting. Students who do not have cell culture experience can gain the required skills by attending our essential cell culture techniques program. If you have any questions regarding your qualifications or suitability for the hPSC workshop, please contact us for more information at

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What are the unique properties of stem cells –

Stell Cell Research | Posted by admin
May 02 2019

Stem cells differ from other kinds of cells in the body. All stem cells-regardless of their source-have three general properties: they are capable of dividing and renewing themselves for long periods; they are unspecialized; and they can give rise to specialized cell types.

Stem cells are capable of dividing and renewing themselves for long periods. Unlike muscle cells, blood cells, or nerve cells-which do not normally replicate themselves-stem cells may replicate many times, or proliferate. A starting population of stem cells that proliferates for many months in the laboratory can yield millions of cells. If the resulting cells continue to be unspecialized, like the parent stem cells, the cells are said to be capable of long-term self-renewal.

Scientists are trying to understand two fundamental properties of stem cells that relate to their long-term self-renewal:

Discovering the answers to these questions may make it possible to understand how cell proliferation is regulated during normal embryonic development or during the abnormal cell division that leads to cancer. Such information would also enable scientists to grow embryonic and non-embryonic stem cells more efficiently in the laboratory.

The specific factors and conditions that allow stem cells to remain unspecialized are of great interest to scientists. It has taken scientists many years of trial and error to learn to derive and maintain stem cells in the laboratory without them spontaneously differentiating into specific cell types. For example, it took two decades to learn how to grow human embryonic stem cells in the laboratory following the development of conditions for growing mouse stem cells. Therefore, understanding the signals in a mature organism that cause a stem cell population to proliferate and remain unspecialized until the cells are needed. Such information is critical for scientists to be able to grow large numbers of unspecialized stem cells in the laboratory for further experimentation.

Stem cells are unspecialized. One of the fundamental properties of a stem cell is that it does not have any tissue-specific structures that allow it to perform specialized functions. For example, a stem cell cannot work with its neighbors to pump blood through the body (like a heart muscle cell), and it cannot carry oxygen molecules through the bloodstream (like a red blood cell). However, unspecialized stem cells can give rise to specialized cells, including heart muscle cells, blood cells, or nerve cells.

Stem cells can give rise to specialized cells. When unspecialized stem cells give rise to specialized cells, the process is called differentiation. While differentiating, the cell usually goes through several stages, becoming more specialized at each step. Scientists are just beginning to understand the signals inside and outside cells that trigger each stem of the differentiation process. The internal signals are controlled by a cell's genes, which are interspersed across long strands of DNA, and carry coded instructions for all cellular structures and functions. The external signals for cell differentiation include chemicals secreted by other cells, physical contact with neighboring cells, and certain molecules in the microenvironment. The interaction of signals during differentiation causes the cell's DNA to acquire epigenetic marks that restrict DNA expression in the cell and can be passed on through cell division.

Many questions about stem cell differentiation remain. For example, are the internal and external signals for cell differentiation similar for all kinds of stem cells? Can specific sets of signals be identified that promote differentiation into specific cell types? Addressing these questions may lead scientists to find new ways to control stem cell differentiation in the laboratory, thereby growing cells or tissues that can be used for specific purposes such as cell-based therapies or drug screening.

Adult stem cells typically generate the cell types of the tissue in which they reside. For example, a blood-forming adult stem cell in the bone marrow normally gives rise to the many types of blood cells. It is generally accepted that a blood-forming cell in the bone marrow-which is called a hematopoietic stem cell-cannot give rise to the cells of a very different tissue, such as nerve cells in the brain. Experiments over the last several years have purported to show that stem cells from one tissue may give rise to cell types of a completely different tissue. This remains an area of great debate within the research community. This controversy demonstrates the challenges of studying adult stem cells and suggests that additional research using adult stem cells is necessary to understand their full potential as future therapies.

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Squamous Cell Carcinoma in Dogs and Cats – Vet360

Stell Cell Research | Posted by admin
May 02 2019

Any tumour growing within (dermal), on (epidermal) or even under the skin (subdermal) should be considered a skin tumour. Some skin tumours are benign (i.e., slow-growing, completely curable with complete resection and dont spread) while others are malignant (faster growing, invasive, sometimes incurable, and may spread to other organs). In order to classify what type of tumour you are dealing with, you will need to make a fine needle aspirate or take a biopsy A biopsy can either be incisional or excisional. Whichever course is taken, a microscopic diagnosis must always, always be obtained.

No two tumours of the same kind look the same, but very different cancers can appear similar When tumours are inflamed or infected, the underlying pathology can be masked. This information is very important. If its a cytological or incisional, this information can help guide you as the best approach to cure not only the obvious lump but also manage the precancerous lesions that surround the obvious tumour. Not all skin tumours are best removed surgically! Only very small (1 2 cm on the body or neck, and

Many clients and vets try to economise by removing small lumps instead of taking the extra step this can drastically alter prognosis, by spreading tumour cells.

Although theoretically any tumour can occur in the skin, we classically think of just a few types when we say skin cancer squamous cell carcinomas (SCC), melanomas, haemangiosarcomas (HSA) and mast cell tumours (MCT).

Actinic Keratosis

Actinic keratosis (AK), also known as solar keratosis or senile keratosis, is a very common lesion occurring in susceptible humans as a result of prolonged and repeated solar exposures. The action of ultraviolet radiant energy, principally UVB, results in damage to the keratinocytes and produces single or multiple, discrete, dry, rough, adherent scaly lesions. These premalignant lesions may, in time, progress to squamous cell carcinomas.

This is very important as a warning sign and should be the first thing you teach clients about. A couple of veterinary-specific manifestations of AK are the comedones or blackheads seen on cats noses (fig 1) and dogs ventra. These lesions can be managed with protection, (fig 2) imiquimod or Photodynamic Therapy (PDT). More on these modalities later.

Squamous Cell Carcinomas

Squamous Cell Carcinomas are the classical skin tumours, caused primarily by long-term to exposure to UV-B radiation. The animals most afflicted white or part-white cats and dogs. Bull Terriers, Staffies, Pit Bulls, Bulldogs and Jack Russells are amongst the dog breeds most often affected. These ex-British breeds enjoy our long, glorious South African summer sun, and tan day after day.

UV-B radiation damages DNA and this damage is cumulative and only partially repairable or reversible. Squamous cell carcinomas can look like nothing more than non-healing crusts, pimples or scabs, or they can form large, raised, ulcerating plaques.


It is important to treat according to the stage presented:

Primary Tumour:

T0 = no tumour

T in situ = Pre-invasive carcinoma (scale, crust)

T1 = tumour

T2 = tumour 2 5 cm diameter, OR with minimal invasion irrespective of size

T3 = tumour > 5cm diameter, or with invasion of subcutis irrespective of size

T4 = invading fascial, muscle, bone or cartilage, regardless of size

Regional lymph nodes:

N0 = no involvement

N1 = lymphnodeinvolvement

Distant metastasis:

M0 = no metastasis

M1 = evidence of metastasis

Ulceration of the primary tumour is associated with a biologically more aggressive lesion and a poorer prognosis. It is not known why ulcerated primaries have a more aggressive biologic nature. It is not likely due to underestimation of the thickness due to the ulcer crater. Ulcerated lesions tend to be thicker and have a nodular growth pattern, but the increased thickness does not account for the poorer prognosis. However, the depth or width of surface ulceration has been significantly correlated with survival. Other histologic prognosticators include the mitotic indices, whirling and the presence or absence of lymphatic or blood vessel invasion are relevant to prognosis.

Tumours in situ look like nothing more than scaly, scabby skin and offer another earlier warning sign, the best opportunity for cure, and are a wake up call. My preference for this is to use immunotherapy with imiquimod cream, or photodynamic therapy for T in situ and T1 tumours.

T2 tumours which are large but NON invasive (T2 large) also respond well to PDT or radiotherapy, but those that are T2 invasive require surgery or aggressive PDT (only to 5mm depth maximum). Once it gets to T2 invasive or T3+, cure rates using any technique drop to below 40% (from >85%) so teach your pet owners about skin cancer and early aggressive intervention from the first vaccination!

T3 and T1-4N/(any) M0/1 must be referred to a specialist for management. I see huge disasters when GPs approach these with surgery. Dogs are disfigured and then referred when they could have kept penises, mobility or faces with a proper approach from the beginning. An integrated approach using multiple modalities and an understanding of tissue tolerances, treatment sequencing and proper patient surveillance are beyond the scope of general practice. Managing such a patient is often possible, but is an 8 20 week process.

More extensive tumours may require additional surgery, chemotherapy or radiation to achieve good results. Their main importance is that they recur because skin of the ventral abdomen, ears or nose have been damaged. (fig 3) Cutting out squamous cell carcinomas can be like the little Dutch boy plugging the hole in the dyke with a finger another often just pops up elsewhere.

Recurrent SCC may require specialist attention to get under control or cure. In any event, thoracic radiographs should be performed. SCC of the feet (pedal SCC) is far more aggressive and spreads to the lungs earlier than other SCC of the skin, so always attend to any non-healing wound or lump of >1 weeks duration by having it checked using histopathology.


Figure 1. White cat with nasal SCC this is the earliest stage the presence of discharge and slight scaling around the nose and eyelids. If treated appropriately at this stage, the prognosis for cure is close to 100%

Figure 2. UV suit UV-resistant suits (obtained from Dr Georgina Crewe), protect the healthy or precancerous skin and are an essential part of post-treatment management

Photodynamic Therapy (PDT) (fig 4) is a technique using the application or injection of photosensitising agents in different concentrations. They accumulate in certain tumours and when subjected to high-fluence (200-300 W/cm2) light of a specific frequency, keyed to the particular molecule being used, the molecules aggregate into unstable complexes that then restabilise by release of various oxygen radicals which cause lipid membrane, protein and DNA damage. Over-treatment causes regional vasoconstriction and side effects, without increase in toxicity; undertreatment achieves little, but aggravates the inflammation. This treatment is effective only in lesions

Immunotherapy using Imiquimod (Aldara; 3M), animidazoquinolinamine, is an immune system modulator and possesses both potent antiviral and antitumor activity in animal models and humans. Current theories suggest that imiquimod acts both directly by inducing apoptosis and by inducing secretion of pro-inflammatory cytokines. Imiquimod activates macrophages and other cells via binding to cell surface receptors, such as Toll receptor 7, and thereby induces secretion of pro-inflammatory cytokines such as interferon-a (IFN-a), tumour necrosis factor-a (TNF-a), and interleukin-12 (IL- 12). These cytokines bias towards a Th1-dominant immune response, which in general is associated with inflammation and tissue injury through activated inflammatory leukocytes and with cytolytic activity through CD8+-lymphocytes (Abbas et al 1996). Imiquimod can also induce apoptosis directly in a Bcl- 2-family-dependent manner by downregulating anti-apoptotic genes such as hurpin and HAX-1.

Treatment is applied to lesions Monday to Friday, once daily, for 6 12 weeks; inflammation caused by the treatment can occasionally be severe and require NSAIDs.

I reserve this for small/early/superficial lesions in cats due to the cost of the cream. Clients must wear gloves to protect themselves. Efficacy is reported as about 75%, with a median survival time of 1189 days, although recurrent lesions do seem to respond to the therapy.

5-Fluorouracil use in animals: this drug is rapidly and fatally neurotoxic in cats even as eye drops. In dogs, the tolerance is also very low and if licked it can trigger fatal mucosal sloughing. Dont use in veterinary practice.

CRYOTHERAPY is outdated, painful, disfiguring and has a lower success rate than other therapies mentioned. Do not use this. Poor technique is a major reason for treatment failure; it requires training and experience and is potentially hazardous to the operator.

RADIATION THERAPY: the use of a linear accelerator to deliver high-voltage (4 20 MeV) electrons or photons for the treatment of surface tumours is called teletherapy. This technique has the potential for extreme harm if improperly performed, and all such cases are specialist cases and must be referred to a person with the relevant training. Theres a reason its an entire field of speciality in itself in the US and Europe. It requires a knowledge of radiation physics, radiation biology and management of radiation side effects that cannot be gleaned from a few lectures.

The role of surgery in managing skin tumours.

Surgery is an important part of management of these conditions. For some tumours e.g. BCC, HA/HSA, MCT, a properly-performed excision can be curative. In others, e.g. SCC, the surrounding skin is often also on an anaplastic march that is unstoppable by surgery alone. Surgery then helps debulk larger masses that would not respond as well to wider-field but lower-intensity therapies e.g. imiquimod, PDT, RT. The timing and planning is critical. Discuss this with a specialist BEFORE radiation or PDT PLEASE! Post-surgical fibrosis decreases the efficacy of other modalities! (fig 5)

Figure 3. SCC ear pinna removal This is the degree of surgery required for more advanced SCC of the pinna, and is to be avoided if possible, by appropriate education of the client at first vaccination of the kitten. This sort of cat may be allowed out at night, but not during the daytime.

Figure 4. PDT Patient undergoing photodynamic therapy at Inanda Vets. Basal Cell Carcinomas

Basal cell tumours are a benign tumour that look very similar to SCC, and are quite common in cats in other parts of the world. In dogs, they typically occur around the head and are not unlike canine cutaneous histiocytoma (hence the need for a tissue diagnosis). They are usually single, raised, ulcerated button-like tumours. Surgery alone is normally curative. They can be diagnosed by cytology or histopathology. BCC and SCC are classed together as the Keratinocytic Skin Cancers.

Figure 5. Multiple raised SCC on the ventrum of a dog; the previous surgeries have contributed to scar tissue formation, which makes radiation less effective, and future surgeries more difficult. The widespread nature of the disease means a novel approach must be taken if control is to be achieved. Patients arriving at this stage are major challenges to cure.


BERGMAN, P. J. 2007. Anticancer vaccines. Vet Clin North Am Small Anim Pract, 37, 1111-9; vi-ii.

BROCKLEY, L. K., COOPER, M. A. & BENNETT, P. F. 2013. Malignant melanoma in 63 dogs (2001-2011): the effect of carboplatin chemotherapy on survival. N Z Vet J, 61, 25-31.

DANK, G., RASSNICK, K. M., SOKOLOVSKY, Y., GARRETT, L. D., POST, G. S., KITCHELL, B. E., SELLON, R. K., KLEITER, M., NORTHRUP, N. & SEGEV, G. 2012. Use of adjuvant carboplatin for treatment of dogs with oral malignant melanoma following surgical excision. Vet Comp Oncol, 9999.

EMANUEL, E. J. & JOFFE, S. 2003. Ethics in Oncology. In: HOLLAND, M. & FREI, E. (eds.) Cancer Medicine 6. 6th ed.: Lippincott.

GILL, V. L., BERGMAN, P. J., BAER, K. E., CRAFT, D. & LEUNG, C. 2008. Use of imiquimod 5% cream (Aldara) in cats with multicentric squamous cell carcinoma in situ: 12 cases (2002-2005). Vet Comp Oncol, 6, 55-64.

GROSENBAUGH, D. A., LEARD, A. T., BERGMAN, P. J., KLEIN, M. K., MELEO, K., SUSANECK, S., HESS., P. R., JANKOWSKI, M. H., KURZMAN, I. & WOLCHOK, J. D. 2011. Safety and efficacy of a xenogeneic DNA vaccine encoding for human tyrosinase as adjunctive treatment for oral malignant melanoma in dogs following surgical excision of the primary tumor. American Journal of Veterinary Research, 72, 1631-1638.

KILLICK, D. R., STELL, A. J. & CATCHPOLE, B. 2015. Immunotherapy for canine canceris it time to go back to the future? J Small Anim Pract, 56, 229-41.

MARTIN, P. D. & ARGYLE, D. J. 2013. Advances in the management of skin cancer. Veterinary Dermatology, 24, 173-e38.

MCLEAN, J. L. & LOBETTI, R. G. 2015. Use of the melanoma vaccine in 38 dogs: The South African experience. J S Afr Vet Assoc, 86, 1246.

OTTNOD, J. M., SMEDLEY, R. C., WALSHAW, R., HAUPTMAN, J. G., KIUPEL, M. & OBRADOVICH, J. E. 2013. A retrospective analysis of the efficacy of Oncept vaccine for the adjunct treatment of canine oral malignant melanoma. Vet Comp Oncol, 11, 219-29.

PETERS-KENNEDY, J., SCOTT, D. W. & MILLER, W. H., JR. 2008. Apparent clinical resolution of pinnal actinic keratoses and squamous cell carcinoma in a cat using topical imiquimod 5% cream. J Feline Med Surg, 10, 593-9.

Photos: Courtesey Inanda Vet (Dr Anthony Zambeli)

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Squamous Cell Carcinoma in Dogs and Cats - Vet360

Pathways to Stem Cell Science | Intro to Stem Cell Systems

Stell Cell Research | Posted by admin
Apr 06 2019


Intro to Stem Cell Systems is an introductory five-day course that explores the exciting science of stem cell research and regenerative medicine. Designed for entry-level scientists, this innovative program provides foundational training in bioscience techniques and essential principles in human stem cell biology. Participating students study the three-major human stem cell systems adult, cancer and pluripotent, through laboratory classes and engaging college-level lectures covering the science, history and ethics of stem cell research. They learn modern skills used by a variety of bioscience professions, working hands-on in a biotech laboratory with cancer, neural and induced pluripotent stem cells.

Each day of the program focuses on a different aspect of stem cell biology, taking students on a stimulating journey from basic discovery to therapeutic translation. Course participants are also introduced to independent research skills, during "stem cell fact or fiction" an interactive lecture-discussion which demonstrates real-life methods for finding published research and applying scientific data to debunk stem cell myths. The program ends with a career development seminar focusing on the many career paths available to bioscientists, led by science professionals with academic and industry experience. This unique course is suited to any motivated science student with an interest in learning more about stem cell research and its current real-world application.

College-level lectures Hands-on lab classes Cutting edge techniques* Guest speakers Literature research Career education Networking with professional science mentors

*Intro to stem cell systems provides practical training in: BSL-2 lab safety procedures, stem cell culture, aseptic technique, tissue microdissection, cell derivation, stem cell isolation, electroporation, antibody labeling and microscopy (phase contrast and fluorescent).

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Pathways to Stem Cell Science | Intro to Stem Cell Systems

Perception of Depth by Michael Kalloniatis and Charles Luu …

Stell Cell Research | Posted by admin
Mar 18 2019

Michael Kalloniatis and Charles Luu


Stereopsis refers to our ability to appreciate depth, that is the ability to distinguish the relative distance of objects with an apparent physical displacement between the objects. It is possible to appreciate the relative location of objects using one eye (monocular cues). However, it is the lateral displacement of the eyes that provides two slightly different views of the same object (disparate images) and allow acute stereoscopic depth discrimination.

Monocular Cues

Several strong monocular cues allow relative distance and depth to be judged. These monocular cues include:

Relative Size: Retinal image size allow us to judge distance based on our past and present experience and familiarity with similar objects. As the car drives away, the retinal image becomes smaller and smaller. We interpret this as the car getting further and further away. This is referred to as size constancy. A retinal image of a small car is also interpreted as a distant car (figure 1).

Figure 1. Relative size. A retinal image of a small car is considered to be distant

Interposition: Interposition cues occur when there is overlapping of objects. The overlapped object is considered further away (figure 2).

Figure 2. Interposition. The blue circle is reported to be closer since it overlaps the red circle

Linear Perspective: When objects of known distance subtend a smaller and smaller angle, it is interpreted as being further away. Parallel lines converge with increasing distance such as roads, railway lines, electric wires, etc (figure 3).

Figure 3. Linear perspective. Parallel lines such as railway lines converge with increasing distance

Aerial Perspective: Relative colour of objects give us some clues to their distance. Due to the scattering of blue light in the atmosphere, creating wall of blue light, distance objects appear more blue (figure 4). Thus distant mountains appear blue. Contrast of objects also provide clues to their distance. When the scattering of light blurs the outlines of objects, the object is perceived as distant. Mountains are perceived to be closer when the atmosphere is clear.

Figure 4. Aerial perspective. Mountains in the distance appear more blue

Light And Shade: Highlights and shadows can provide information about an objects dimensions and depth (figure 5). Because our visual system assumes the light comes from above, a totally different perception is obtained if the image is viewed upside down.

Figure 5. Highlights and shadows provide information about depth

Monocular Movement Parallax: When our heads move from side to side, objects at different distances move at a different relative velocity. Closer objects move against the direction of head movement and farther objects move with the direction of head movement.

Binocular Cues

Stereopsis is an important binocular cue to depth perception. Stereopsis cannot occur monocularly and is due to binocular retinal disparity within Panums fusional space. Stereopsis is the perception of depth produced by binocular retinal disparity. Therefore, two objects stimulates disparate (non-corresponding) retinal points within Panums fusional area.

Fusion describes the neural process that brings the retinal images in the two eyes to form one single image. Fusion occurs to allow single binocular vision. Fusion takes place when the objects are the same. When the objects are different, suppression, superimposition or binocular (retinal) rivalry may occurs. Suppression occurs to eliminate one image to prevent confusion. Superimposition results in one image presented on top of the other image. Binocular rivalry describes alternating suppression of the two eyes resulting in alternating perception of the two images. This usually occurs when lines are presented to the two eyes differ in orientation, length or thickness. An example of binocular rivalry occurs when one eye is presented with a horizontal line and the other eye is presented with a vertical line. Binocular rivalry occurs at the intersection of the lines and some suppression also exists (figure 6)

Figure 6. (a) Binocular rivalry can be demonstrated by placing a pen between yourself and the screen. Keep you eye on the tip of the pen and notice the two bars merge. You may need to slowly move the pen from the screen towards you. (b) Result of (a)

Panums fusional area is the region of binocular single vision. Outside Panums fusional area, physiological diplopia occurs. Using the haplopic method of determining the horopter, Panums area can be determined (figure 7).

Figure 7. Haplopic method of determining the horopter involves locating the region of single binocular vision at a distance of 40cm.Panums fusional area lies between the outer and inner limits of the region of single binocular vision

Retinal disparity: Retinal disparate points are retinal points that give rise to different principal visual direction and diplopia. However, retinal disparity within Panums fusional area (zone of single binocular vision) can be fused resulting in single vision. Retinal disparity is essential for stereoscopic depth perception as stereoscopic depth perception results from fusion of slightly dissimilar images. Due to the lateral displacement of our eyes, slightly dissimilar retinal images result from the different perception of the same object from each eye.

Clinical Tests used to measure Stereopsis

There are two groups of clinical tests used to measure stereopsis. These are the contour stereotests and the random-dot stereotest. Random-dot stereograms were first used by Julesz (1960) to eliminate monocular cues. As there are no contours, depth perception (stereopsis) can only be appreciated when binocular fusion occurs. Two process of stereopsis are used and these are local and global stereopsis. Local stereopsis exists to evaluate the two horizontally disparate stimuli. This process is sufficient for contour stereotests. Global stereopsis is required in random-dot stereogram when the evaluation and correlation of corresponding points and disparate points are needed over a large retinal area.

An example of a contour stereotest used in the clinic is the Titmus Fly Stereotest. In the Titmus Fly Stereotest, horizontal disparity is presented via the vectographic technique (Fricke and Siderov, 1997). When tested a 40 cm the fly has a disparity of 3,600 sec of arc; the disparity of the animals range from 400 100 sec of arc and the disparity of the Wirt rings range from 800 40 sec of arc (figure 8).

Figure 8. Titmus Fly Stereotest

Examples of random-dot stereotests used in the clinic are the Frisby Stereotest, the Randot Stereotest, the Random-dot E Stereotest and the Lang Stereotest. The Frisby Stereotest (figure 9) uses real depth to determine stereoacuity. Three perspex of different thicknesses are used. Four squares of geometric shapes are painted on one side of the perspex. In one of the squares, a circle of these geometric shape is painted on the other side of the perspex. Both the Randot (figure 10) and the Random-dot E uses crossed polarised filters. Disparity is also constructed vectographically. The Randot Stereotest uses modified animals and ring designs with random dot backgrounds to eliminate monocular cues. The Lang Stereotest uses a panographic technique (Fricke and Siderov, 1997) to present disparity, therefore, no filters are required. Patients are required to identify pictures on the Lang Stereotest. The Lang II Stereotest has a monocularly visible shape on it (figure 11).

Figure 11. The Lang II

All the tests provides a measure of stereoacuity by asking the patient to identify the correct target that has stereoscoptic depth (target with disparity). The working distance and interpupillary distance will need to be taken into consideration when calculating stereoacuity. Patients with disturbed binocular vision or different refractive error in one eye, will perform poorly on depth discrimination tests.


We like to thank Tim Fricke for providing Figures 8-11.


Fricke TR and Siderov J (1997) Stereopsis, stereotest and their relation to vision screening and clinical practice.Clin Exp Optom. 80: 165-172.

Julesz B. Binocular depth perception of computer generated patterns.Bell Syst Tech J.1960;39:11251162.2.

Moses RA and Hart WM (1987)Adlers Physiology of the eye, Clinical Application, 8th ed. St. Louis: The C. V. Mosby Company.

Ogle KN (1950)Researches in Binocular Vision. London: Saunders. 1950

Schwartz SH (1999)Visual Perception, 2nd ed. Connecticut: Appleton and Lange.

Last Update: June 6, 2007.

The author

Michael Kalloniatiswas born in Athens Greece in 1958. He received his optometry degree and Masters degree from the University of Melbourne. His PhD was awarded from the University of Houston, College of Optometry, for studies investigating colour vision processing in the monkey visual system. Post-doctoral training continued at the University of Texas in Houston with Dr Robert Marc. It was during this period that he developed a keen interest in retinal neurochemistry, but he also maintains an active research laboratory in visual psychophysics focussing on colour vision and visual adaptation. He was a faculty member of the Department of Optometry and Vision Sciences at the University of Melbourne until his recent move to New Zealand. Dr. Kalloniatis is now the Robert G. Leitl Professor of Optometry, Department of Optometry and Vision Science, University of

The author

Charles Luuwas born in Can Tho, Vietnam in 1974. He was educated in Melbourne and received his optometry degree from the University of Melbourne in 1996 and proceeded to undertake a clinical residency within the Victorian College of Optometry. During this period, he completed post-graduate training and was awarded the post-graduate diploma in clinical optometry. His areas of expertise include low vision and contact lenses. During his tenure as a staff optometrist, he undertook teaching of optometry students as well as putting together the Cyclopean Eye, in collaboration with Dr Michael Kalloniatis. The Cyclopean Eye is a Web based interactive unit used in undergraduate teaching of vision science to optometry students. He is currently in private optometric practice as well as a visiting clinician within the Department of Optometry and Vision Science, University of Melbourne.

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Why does my DAB signal disappear so quickly?

Stell Cell Research | Posted by admin
Mar 10 2019

Hi everyone,

Great suggestions, thanks for sharing your thoughts. I have tried using fresh dehydrating alcohols, but still got the same results. I may try some of the different mounting media you suggested and a different source of DAB. I have not tried leaving out the differentiation step with acid alcohol. Is there a particular bluing reagent that works best?

The details of my protocol are as follows:

The sections were fixed in Modified Davidsons solution, paraffin embedded, re-hydrated, underwent sodium citrate heat-mediated antigen retrieval for 20 minutes, rinsed in PBS, incubated with 10% normal goat serum in PBS for 1 hour at room temperature, incubated with primary antibody in PBS overnight at 4 degrees C, rinsed in PBS, quenched for endogenous peroxidase in 3% hydrogen peroxidase for 15 minutes, rinsed in PBS, incubated with biotinylated secondary antibody in PBS for 1 hour at room temperature, rinsed in PBS, incubated with avidin and biotinylated horseradish peroxidase complex for 30 minutes, rinsed in PBS, developed with DAB (Invitrogen) for 1-2 minutes, counterstained with hematoxylin, rinsed in water, differentiated in acid alcohol, rinsed in water, blued in 0.2% ammonia water, rinsed in water, dehydrated in three changes of isopropanol, cleared through three changes of xylene, and mounted using Cytoseal XYL.

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Why does my DAB signal disappear so quickly?

Atmospheric & Environmental Chemistry | Aerodyne Research …

Stell Cell Research | Posted by admin
Mar 06 2019

Development of a NOx chemistry module for EDMS/AEDT to predict NO2 concentrations, R. Miake-Lye, S. Herndon, M. Kenney, ACRP, National Academy of Sciences, 2017.

Revisiting global fossil fuel and biofuel emissions of ethane, Z. A. Tzompa-Sosa, E. Mahleu, B. Franco, C. A. Keller, A. J. Turner, D. Helmig, A. Fried, D. Richter, P. Welbring, J. Walega, T. L. Yacovitch, S. C. Herndon, D. R. Blake, F. Hase, J. W. Hannigan, S. Conway, K. Strong, M. Schnelder, E. V. Fischer,J. Geophys. Atmos,, 122, 2493-2512, 2017.

Dynamics of canopy stomatal conductance, transpiration, and evaporation in a temperate decidious forest, validated by carbonyl sulfide uptake, R. Wehr, R. Commane, J. Munger, J. B. McManus, D. Nelson, M. Zahniser, S. Saleska, S. Wofsy, Biogeosciences,14, 389-401, 2017.

Interannual variability of ammonia concentrations over the United States: sources and implications, L. D. Schiferl, C. L. Heald, M. Van Damme, L. Clarisse, C. Clerbaux, P. Coheur, J. B. Nowak, J. A. Neuman, S. C. Herndon, J. R. Roscioli, S. J. Ellerman, Atmos. Chem. Phys., 16, 12305-12328, 2016.

Using airborne technology to quantify and apportion emissions of CH4 and NH3 from feedlots, J. M. Hacker, D. Chen, M. Bai, C. Ewenz, W. Junkermann, W. Lieff, B. McManus, B. Neininger, J. Sun, T. Coates, T. Denmead, T. Flesch, S. McGinn, J. Hill, Animal Production Science, 56, 190-203, 2016.

Exhaust emissions from in-use general aviation aircraft, T. I. Yacovitch, Z. Yu, S. C. Herndon, R. Miake-Lye, D. Liscinsky, W. B. Knighton, M. Kenney, C. Schoonard, P. Pringle, Airport Cooperative Research Program, 2016.

Continuous and high-precision atmospheric concentration measurements of COS, CO2, CO and H2O using a quantum cascade laser specrometer (QCLS), L. M. J. Kooijmans, N. A. M. Uitslag, M. S. Zahniser, D. D. Nelson, S. A. Montzka, H. Chen, Amos. Meas. Tech., 9, 5293-5314, 2016.

Characterization of ammonia, methane, and nitrous oxide emissions from concentrated animal feeding operations in northeastern colorado, S. J. Eilerman, J. Peischl, J. A. Neuman, T. B. Ryerson, K. C. Aikin, M. W. Holloway, M. A. Zondlo, L. M. Golston, D. Pan, C. Floerchinger, S. Herndon, Env. Sci. & Technol., 50, 10885-10903, 2016.

Impacts of the Denver Cyclone on regional air quality and aerosol formation in the Colorado Front Range during FRAPPE 2014, K. T. Vu, J. H. Dingle, R. Bahreini, P. J. Reddy, E. C. Apel, T. L. Campos, J. P. DiGangi, G. S. Diskin, A. Freid, S. C. Herndon, A. J. Hills, R. S. Hornbrook, G. Huey, L. Kaser, D. D. Montzka, J. B. Nowak, S. E. Pusede, D. Richter, J. R. Roscioli, G. W. Sachse, S. Shertz, M. Stell, D. Tanner, G. S. Tyndall, J. Walega, P. Weibring, A. J. Weinheimer, G. Pfister, F. Flocke, Atmos. Chem. Phys., 16, 12039-12058, 2016.

Seasonal and diurnal variation in CO fluxes from an agricultural bioenergy crop, M. Pihlatie, U. Rannik, S. Haapanala, O. Peltola, N. Shurpali, P. J. Martikainen, S. Lind, N. Hyvonen, P. Virkajarvi, M. Zahniser, I. Mammarella, Biogeosciences, 13, 5471-5485, 2016.

Surface-atmosphere exchange of ammonia over peatland using QCL-based eddy-covariance measurements and inferential modeling, U. Zoll, C. Brummer, F. Shcrader, C. Ammann, A. Ibrom, C. R. Flechard, D. D. Nelson, M. Zahniser, W. L. Kutsh, Atmos. Chem. Phys. 16, 11283-11299, 2016.

Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) 2014 summertime field campaign, Colorado, USA, J. H. Dingle, K. Vu, R. Bahreini, E. C. Apel, T. L. Campos, F. FLocke, A. Fried, S. Herndon, A. J. Hills, R. S. Hornbrook, G. Huey, L. Kaser, D. D. Montzka, J. B. Nowak, M. Reeves, D. Richter, J. R. Roscioli, S. Shertz, M. Stell, D. Tanner, G. Tyndall, J. Walega, P. Weibring, A. Weinheimer, Atmos. Chem. Phys., 16, 11207-11217, 2016.

Direct and indirect measurements and modeling of methane emissions in Indianapolis, Indiana, B. K. Lamb, M. Cambaliza, K. J. Davis, S. L. Edburg, T. W. Ferrara, C. Floerchinger, A. M. Heimburger, S. Herndon, T. Lauvaux, T. Lavoie, D. R. Lyon, N. Miles, K. R. Prasad, S. Richardson, J. R. Roscioli, O. E. Salmon, P. B. Shepson, B. H. Stirm, J. Whetstone, Environ. Sci. Technol, 16, 8910-7, 2016.

Seasonality of temperate forest photosynthesis and daytime respiration, R. Wehr, J.W. Munger, J. B. McManus, D. D. Nelson, M. S. Zahniser, E. A. Davidson, S. C. Wofsy, S. R. Saleska, Nature Letter, 534, 680-683, 2016.

Dynamics of Ammonia Volatilisation Measured by Eddy Covariance During Slurry Spreading in North Italy, Rossana Monica Ferrara, Marco Carozzi, Paul Di Tommasi, David D. Nelson, Gerardo Fratini, Teresa Bertolini, Vincenzo Magliulo, Marco Acutis, Gianfranco Rana, Agriculture, Ecosystems & Environment, 219, 1-13, 2016.

The Development and Evaluation of Airborne in Situ N2O and CH4 Sampling Using a Quantum Cascade Laser Absorption Spectrometer (QCLAS) J. R. Pitt, M. LeBreton, G. Allen, C. J. Percival, M. W. Gallagher, S. J.-B. Bauguitte, S. J. O'Shea, J. B. A. Muller, M. S. Zahniser, J. Pyle, P. I. Palmer, Atmos. Meas. Tech., 9, 63-77, 2016.

Reconciling Divergent Estimates of Oil and Gas Methane Emissions, Daniel Zavala-Araizaa, David R. Lyona, Ramn A. Alvareza, Kenneth J. Davisb, Robert Harrissa, Scott C. Herndon, Anna Kariond, Eric Adam Kortf, Brian K. Lambg, Xin Lanh, Anthony J. Marchesei, Stephen W. Pacalaj, Allen L. Robinsonk, Paul B. Shepsonl, Colm Sweeneyd, Robert Talboth, Amy Townsend-Smallm, Tara I. Yacovitchc, Daniel J. Zimmerlei, Steven P. Hamburg, PNAS, 112, 1559715602, 2015.

Air Pollutant Mapping with a Mobile Laboratory During the BEE-TEX Field Study, Tara I. Yacovitch1, Scott C. Herndon, Joseph R. Roscioli1, Cody Floerchinger,W. Berk Knighton, Charles E. Kolb, Supplementary Issue: Ambient Air Quality (B), Environmental Health Insights, 9, 7-13, 2015.

New Approaches to Measuring Sticky Molecules: Improvement of Instrumental Response Times Using Active Passivation, J. R. Roscioli, M. S. Zahniser, D. D. Nelson, S. C. Herndon, C. E. Kolb, J. Phys. Chem. A, (Web): June 24, 2015.

Seasonal fluxes of carbonyl sulfide in a midlatitude forest, R. Commanea, L. K. Meredith, I. T. Baker, J. A. Berry, J. W. Munger, S. A. Montzka, P. H. Templer, S. M. Juice, M. S. Zahniser, S. C. Wofsy, PNAS, 112, 14162-14167, 2015.

Recent progress in laser-based trace gas instruments: performance and noise analysis, J. B. McManus, M. S. Zahniser, D. D. Nelson, J. H. Shorter, S. C. Herndon, D. Jervis, M. Agnese, R. McGovern, T. I. Yacovitch, J. R.Roscioli, Appl. Phys. B: Lasers Opt., 119, 203-218, 2015.

Methane Emissions from United States Natural Gas Gathering and Processing, A. J. Marchese, T. L. Vaughn, D. J. Zimmerle, D. M. Martinez, L. L. Williams, A. L. Robinson, A. L. Mitchell, R. Subramanian, D. S. Tkacik, J. R. Roscioli, S. C. Herndon, Environ. Sci. Technol., 49, 10718-10727, 2015.

Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts, K. McKain, A. Down, S. M. Raciti, J. Budney, L. R. Hutyra, C. Floerchinger, S. C. Herndon, T. Nehrkorn, M. S. Zahniser, R. B. Jackson, N. Phillips, S. C. Wofsy PNAS, 112, 1941-1946, 2015.

Meteorology, Air Quality, and Health in London: The ClearfLo Project, S. I. Bohnenstengel, S. E. Belcher, A. Aiken, J. D. Allan, G. Allen, A. Bacak, T. J. Bannan, J. F. Barlow, D. C. S. Beddows, W. J. Bloss, A. M. Booth, C. Chemel, O. Coceal, C. F. Di Marco, M. K. Dubey, K. H. Faloon, Z. L. Fleming, M. Furger, J. K. Gietl, R. R. Graves, D. C. Green, C. S. B. Grimmond, C. H. Halios, J. F. Hamilton, R. M. Harrison, M. R. Heal, D. E. Heard, C. Helfter, S. C. Herndon, R. E. Holmes, J. R. Hopkins, A. M. Jones, F. J. Kelly, S. Kotthaus, B. Langford, J. D. Lee, R. J. Leigh, A. C. Lewis, R. T. Lidster, F. D. Lopez-Hilfiker, J. B. McQuaid, C. Mohr, P. S. Monks, E. Nemitz, N. L. Ng, C. J. Percival, A. S. H. Prvt, H. M. A. Ricketts, R. Sokhi, D. Stone, J. A. Thornton, A. H. Tremper, A. C. Valach, S. Visser, L. K. Whalley, L. R. Williams, L. Xu, D. E. Young, P. Zotter, Bull. Amer. Meteor. Soc., 96, 779804, 2015.

Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region, D. R. Lyon, D. Zavala-Araiza, R. A. Alvarez, R. Harriss, V. Palacios, X. Lan, R. Talbot, T. Lavoie, P. Shepson, T. I. Yacovitch, S. C. Herndon, A. J. Marchese, D. Zimmerle, A. L. Robinson, S. P. Hamburg, Environ. Sci. Technol., 49, 81478157, 2015.

Mobile Laboratory Observations of Methane Emissions in the Barnett Shale Region, T. I. Yacovitch, S. C. Herndon, G. Ptron, J. Kofler, D. Lyon, M. S. Zahniser, C. E. Kolb, Environ. Sci. Technol., 49, 78897895, 2015.

Airborne Ethane Observations in the Barnett Shale: Quantification of Ethane Flux and Attribution of Methane Emissions, M. L. Smith, E. A. Kort, A. Karion, C. Sweeney, S. C. Herndon, T. I. Yacovitch, Environ. Sci. Technol., 49, 81588166, 2015.

Aircraft-Based Estimate of Total Methane Emissions from the Barnett Shale Region, A. Karion, C. Sweeney, E. A. Kort, P. B. Shepson, A. Brewer, M. Cambaliza, S. A. Conley, K. Davis, A. Deng, M. Hardesty, S. C. Herndon, T. Lauvaux, T. Lavoie, D. Lyon, T. Newberger, G. Ptron, C. Rella, M. Smith, S. Wolter, T. I. Yacovitch, P. Tans, Environ. Sci. Technol., 49, 81248131, 2015.

Aircraft-Based Measurements of Point Source Methane Emissions in the Barnett Shale Basin, T. N. Lavoie, P. B. Shepson, M. O. L. Cambaliza, B. H. Stirm, A. Karion, C. Sweeney, T. I. Yacovitch, S. C. Herndon, X. Lan, D. Lyon, Environ. Sci. Technol., 49, 79047913, 2015.

Atmospheric Emission Characterization of Marcellus Shale Natural Gas Development Sites, J. D. Goetz, C. Floerchinger, E. C. Fortner, J. Wormhoudt, P. Massoli, W. B. Knighton, S. C. Herndon, C. E. Kolb, E. Knipping, S. L. Shaw, P. F. DeCarlo, Environ. Sci. Technol., 49, 70127020, 2015.

Vehicle emissions of radical precursors and related species observed in the 2009 SHARP campaign, J. Wormhoudt, E. C. Wood, W. B. Knighton, C. E. Kolb, S. C. Herndon, E. P. Olague, J. Air Waste Manage. Assoc., 65, 699-706, 2015.

Airborne in situ vertical profiling of HDO/H216O in the subtropical troposphere during the MUSICA remote sensing validation campaign, C. Dyroff, S. Sanati, E. Christner, A. Zahn, M. Balzer, H. Bouquet, J. B. McManus, Y. Gonzlez-Ramos, M. Schneider, Atmos. Meas. Tech. Discuss., 8, 121155, 2015.

Design and performance of a dual-laser instrument for multiple isotopologues of carbon dioxide and water, J. B. McManus, D. D. Nelson, M. S. Zahniser, Opt. Express, 23, 6569-6586, 2015.

Intercomparison of fast response commercial gas analysers for nitrous oxide flux measurements under field conditions, . Rannik, S. Haapanala, N. J. Shurpali, I. Mammarella, S. Lind, N. Hyvnen, O. Peltola, M. Zahniser, P. J. Martikainen, T. Vesala, Biogeosciences, 12, 415-431, 2015.

Development and field testing of a rapid and ultra-stable atmospheric carbon dioxide spectrometer, B. Xiang, D. D. Nelson, J. B. McManus, M. S. Zahniser, R. A. Wehr, S. C. Wofsy, Atmos. Meas. Tech., 7, 4445-4453, 2014.

Feasibility and Potential Utility of Multicomponent Exhaled Breath Analysis for Predicting Development of Radiation Pneumonitis after Stereotactic Ablative Radiotherapy, J. M. Mor, N. C.W. Eclov, M. P. Chung, J. F. Wynne, J. H. Shorter, D. D. Nelson, A. L. Hanlon, R. Burmeister, P. Banos, P. G. Maxim, B. W. Jr Loo, M. Diehn, J. Thorac. Oncol., 9, 957-964, 2014.

Demonstration of an Ethane Spectrometer for Methane Source Identification, T. I. Yacovitch, S. C. Herndon, J. R. Roscioli, C. Floerchinger, R. M. McGovern, M. Agnese, G. Ptron, J. Kofler, C. Sweeney, A. Karion, S. A. Conley, E. A. Kort, L. Nhle, M. Fischer, L. Hildebrandt, J. Koeth, J. B. McManus, D. D. Nelson, M. S. Zahniser, C. E. Kolb, Environ. Sci. Technol., 48, 8028-8034, 2014.

Sources and sinks of carbonyl sulfide in an agricultural field in the Southern Great Plains, K. Maseyk, J. A. Berry, D. Billesbach, J. E. Campbell, M. S. Torn, M. Zahniser, U. Seibt, PNAS, 111, 9064-9069, 2014.

Measurement of a doubly substituted methane isotopologue, 13CH3D, by tunable infrared laser direct absorption spectroscopy, S. Ono, D. T. Wang, D. S. Gruen, B. S. Lollar, M. S. Zahniser, B. J. McManus, D. D. Nelson, Anal. Chem., 86, 64876494, 2014.

Greenhouse gas budget (CO2, CH4 and N2O) of intensively managed grassland following restoration, L. Merbold, W. Eugster, J. Stieger, M. Zahniser, D. Nelson, N. Buchmann, Global Change Biol., 20, 19131928, 2014.

Simulation of semi-explicit mechanisms of SOA formation from glyoxal in a 3-D model, C. Knote, A. Hodzic, J. L. Jimenez, R. Volkamer, J. J. Orlando, S. Baidar, J. Brioude, J. Fast, D. R. Gentner, A. H. Goldstein, P. L. Hayes, W. B. Knighton, H. Oetjen, A. Setyan, H. Stark, R. Thalman, G. Tyndall, R. Washenfelder, E. Waxman, Q. Zhang, Atmos. Chem. Phys., 14, 6213-6239, 2014.

Evaluation of the airborne quantum cascade laser spectrometer (QCLS) measurements of the carbon and greenhouse gas suite CO2, CH4, N2O, and CO during the CalNex and HIPPO campaigns, G. W. Santoni, B. C. Daube, E. A. Kort, R. Jimnez, S. Park, J. V. Pittman, E. Gottlieb, B. Xiang, M. S. Zahniser, D. D. Nelson, J. B. McManus, J. Peischl, T. B. Ryerson, J. S. Holloway, A. E. Andrews, C. Sweeney, B. Hall, E. J. Hintsa, F. L. Moore, J. W. Elkins, D. F. Hurst, B. B. Stephens, J. Bent, and S. C. Wofsy, Atmos. Meas. Tech., 7, 1509-1526, 2014.

Measurement of a doubly substituted methane isotopologue, 13CH3D, by tunable infrared laser direct absorption spectroscopy, S. Ono, D. T. Wang, D. S. Gruen, B. S. Lollar, M. S. Zahniser, B. J. McManus, D. D. Nelson, Anal.Chem, (Web): June 4, 2014.

Intercomparison of field measurements of nitrous acid (HONO) during the SHARP campaign, J. P. Pinto, J. Dibb, B. H. Lee, B. Rappenglck, E. C. Wood, M. Levy, R.-Y. Zhang, B. Lefer, X.-R. Ren, J. Stutz, C. Tsai, L. Ackermann, J. Golovko, S. C. Herndon, M. Oakes, Q.-Y. Meng, J. W. Munger, M. Zahniser,J. Zheng, J. Geophys. Res. Atmos., 119, 55835601, DOI: 10.1002/2013JD020287, 2014.

Development of a Spectroscopic Technique for Continuous Online Monitoring of Oxygen and Site-Specific Nitrogen Isotopic Composition of Atmospheric Nitrous Oxide, E. Harris, D. D. Nelson, W. Olszewski, M. Zahniser, K. E. Potter, B. J. McManus, A. Whitehill, R. G. Prinn, S. Ono, Anal. Chem., 86, 17261734, 2014.

Urban measurements of atmospheric nitrous acid: A caveat on the interpretation of the HONO photostationary state, B. H. Lee, E. C. Wood, S. C. Herndon, B. L. Lefer, W. T. Luke, W. H. Brune, D. D. Nelson, M. S. Zahniser, J. W. Munger, J. Geophys. Res. Atmos., 118, 12,27412,281, doi:10.1002/2013JD020341 2013.

Carbonyl sulfide in the planetary boundary layer: Coastal and continental influences, R. Commane, S. C. Herndon, M. S. Zahniser, B. M. Lerner, J. B. McManus, J. W. Munger, D. D. Nelson, S. C. Wofsy, JGR, Atmos. 118, Issue 14, 80018009, DOI:10.1002/jgrd.5058, 2013.

Measurements of methane emissions at natural gas production sites in the United States, D. T. Allen, V. M. Torres, J. Thomas, D. W. Sullivan, M. Harrison, A. Hendler, S. C. Herndon, C. E. Kolb, M. P. Fraser, A. D. Hill, B. K. Lamb, J. Miskimins, R. F. Sawyer, J. H. Seinfeld, PNAS, 110, 17768-17773, 2013.

Contribution of Nitrated Phenols to Wood Burning Brown Carbon Light Absorption in Detling, United Kingdom during Winter Time, C. Mohr, F. D. Lopez-Hilfiker, P. Zotter, A. S. H. Prvt, L. Xu, N. L. Ng, S. C. Herndon, L. R. Williams, J. P. Franklin, M. S. Zahniser, D. R. Worsnop, W. B. Knighton, A. C. Aiken, K. J. Gorkowski, M. K. Dubey, J. D. Allan, J. A. Thornton, Environ. Sci. Technol., 47, 63166324, 2013.

Long-term eddy covariance measurements of the isotopic composition of the ecosystematmosphere exchange of CO2 in a temperate forest, R. Wehr, J. W. Munger, D. D. Nelson, J. B. McManus, M. S. Zahniser, S. C. Wofsy, S. R. Saleska, Agric. For. Meteorol., 181, 69-84, 2013.

Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft, E. S. Cross, J. F. Hunter, A. J. Carrasquillo, J. P. Franklin, S. C. Herndon, J. T. Jayne, D. R. Worsnop, R. C. Miake-Lye, and J. H. Kroll, Atmos. Chem. Phys., 13, 7845-7858, 2013.

Towards a stable and absolute atmospheric carbon dioxide instrument using spectroscopic null method, B. Xiang, D. D. Nelson, J. B. McManus, M. S. Zahniser, S. C. Wofsy, Atmos. Meas. Meas. Tech., 6, 1611-1621, 2013.

Selective measurements of NO, NO2 and NOy in the free troposphere using quantum cascade laser spectroscopy, B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser, L. Emmenegger, Atmos. Meas. Tech. Discuss., 5, 89698993, 2012.

Detecting fugitive emissions of 1,3-butadiene and styrene from a petrochemical facility: An application of a mobile laboratory and a modified proton transfer reaction mass spectrometer, W. B. Knighton, S. C. Herndon, E. C. Wood, E. C. Fortner, T. B. Onasch, J. Wormhoudt, C. E. Kolb, B. H. Lee, M. Zavala, L. Molina, M. Jones, Industrial & Engineering Chemistry Research, 51, 1267412684, 2012.

Direct measurement of volatile organic compound emissions from industrial flares using real-time online techniques: Proton transfer reaction mass spectrometry and tunable infrared laser differential absorption spectroscopy, W. B. Knighton, S. C. Herndon, J. F. Franklin, E. C. Wood, J. Wormhoudt, W. Brooks, E. C. Fortner, D. T. Allen, Industrial & Engineering Chemistry Research, 51, 1267412684, 2012.

Industrial flare performance at low flow conditions. 1. Study overview, V. M. Torres, S. Herndon, Z. Kodesh, D. T. Allen, Ind. Eng. Chem. Res., 51, 12559-12568, 2012.

Industrial flare performance at low flow conditions. 2. Steam- and air-assisted flares, V. M. Torres, S. Herndon, D. T. Allen, Ind. Eng. Chem. Res., 51, 12569-12576, 2012.

Application of the carbon balance method to flare emissions characteristics, S. C. Herndon, D. D. Nelson, Jr., E. C. Wood, W. B. Knighton, C. E. Kolb, Z. Kodesh, V. M. Torres, D. T. Allen, Ind. Eng. Chem. Res., 51, 12577-12585, 2012.

Emissions of nitrogen oxides from flares operating at low flow conditions, V. M. Torres, S. Herndon, E. Wood, F. M. Al-Fadhli, D. T. Allen, Ind. Eng. Chem. Res., 51, 12600-12605, 2012.

Effective line strengths of trans-nitrous acid near 1275 cm-1 and cis-nitrous acid at 1660 cm-1 , B. H. Lee, E. C. Wood, J. Wormhoudt, J. H. Shorter, M. S. Zahniser, J. W. Munger, J. Quant. Spectrosc. Radiat. Transfer, 113, 1905-1912, 2012.

Mass fluxes and isofluxes of methane (CH4) at a New Hampshire fen measured by a continuous wave quantum cascade laser spectrometer. G. W. Santoni, B. H. Lee, J. P. Goodrich, R. K. Varner, P. M. Crill, J. Barry McManus, D. D. Nelson, M. S. Zahniser, S. C. Wolfsy, JGR 117, D10301, doi:10.1029/2011JD016960, 15pp., 2012.

Modelled and measured concentrations of peroxy radicals and nitrate radical in the US Gulf Coast region during TexAQS 2006, R. Sommariva, T. S. Bates, D. Bon, D. M. Brookes, J. A. de Gouw, S. C. Herndon, W. C. Kuster, B. M. Lerner, P. S. Monks, H. D. Osthoff, A. E. Parker, J. M. Roberts, S. C. Tucker, C. Warneke, E. J. Williams, M. S. Zahniser, S. S. Brown, J. Atmos. Chem. 68, 331-362, 2012.

Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region, D. D. Parrish, T. B. Ryerson, J. Mellqvist, J. Johansson, A. Fried, D. Richter, J. G. Walega, R. A. Washenfelder, J. A. de Gouw, J. Peischl, K. C. Aikin, S. A. McKeen, G. J. Frost, F. C. Fehsenfeld, S. C. Herndon, Atmos. Chem. Phys. 12, 3273-3288, 2012.

Establishing Policy Relevant Background (PRB) Ozone Concentrations in the United States, E. C. McDonald-Buller, D. T Allen, N. Brown, D. J. Jacob, D. Jaffe, C. E. Kolb, A. S. Lefohn, S. Oltmans, D. D. Parrish, G. Yarwood, L. Zhang, Environ. Sci. Tech. 45, 9484-9497, 2011.

Measurements of nitrous acid in commercial aircraft exhaust at the alternative aviation fuel experiment, B. H. Lee, G. W. Santoni, E. C. Wood, S. C. Herndon, R. C. Miake-Lye, M. S. Zahniser, S. C. Wofsy, J. W. Munger, Environ. Sci. Tech. 45, 7648-7651, 2011.

Monomer, clusters, liquid: an integrated spectroscopic study of methanol condensation, H. Laksmono, S.Tanimura, H. C. Allen, G. Wilemski, M. S. Zahniser, J. H. Shorter, D. D. Nelson, J. B. McManus, B. E. Wyslouzil, Phys. Chem. Chem. Phys., 13, 5855-5871, 2011.

Measurements of volatile organic compounds at a suburban ground site (T1) in Mexico City during the MILAGRO 2006 campaign: measurement comparison, emission ratios, and source attribution, D. M. Bon, I. M. Ulbrich, J. A. de Gouw, C. Warneke, W. C. Kuster, M. L. Alexander, A. Baker, A. J. Beyersdorf, D. Blake, R. Fall, J. L. Jimenez, S. C. Herndon, L. G. Huey, W. B. Knighton, J. Ortega, S. Springston, O. Vargas, Atmos. Chem. Phys., 11, 2399-2421, 2011.

Ozone production in remote oceanic and industrial areas derived from ship based measurements of peroxy radicals TexAQS 2006, R. Sommariva, S. S. Brown, J. M. Roberts, D. M. Brookes, A. E. Parker, P. S. Monke, T. S. Bates, D. Bon, J. A. De Gouw, G. .J. Frost, J. B. Gilman, P. D. Goldan, S. C. Herndon, W. C. Kuster, B. M. Lerner, H. D. Osthuff, S. C. Tucker, C. Warneke, E. J. Williams, M. S. Zahniser, Atmos. Chem. Phys., 11, 2471-2485, 2011.

Dual quantum cascade laser trace gas instrument with astigmatic Herriott cell at high pass number, J. B. McManus, M. S. Zahniser, D. D. Nelson, Appl. Opt., 50, A74-A84, 2011.

Investigation of the correlation between odd oxygen and secondary organic aerosol in Mexico City and Houston, E. C. Wood, M. R. Canagaratna, S. C. Herndon, T. B. Onasch, C. E. Kolb, D. R. Worsnop, J. H. Kroll, W. B. Knighton, R. Seil, M. Zavala, L. T. Molina, P. F. DeCarlo, J. L. Jimenez, A. J. Weinheimer, D. J. Knapp, B. T. Jobson, J. Stutz, W. C. Kuster, and E. J. Williams, Atmos. Chem. Phys 10, 8947-8968, 2010.

Application of quantum cascade lasers to high-precision atmospheric trace gas measurements, J. B. McManus, M. S. Zahniser, D. D. Nelson Jr., J. H. Shorter, S. Herndon, E. Wood, F. Wehr, Opt. Eng. 49, 111124, 2010.

Gas turbine engine emissions - Part I: Volatile organic compounds and nitrogen oxides, M. T. Timko, S. C. Herndon, E. C. Wood, T. B. Onasch, M. J. Northway, J. T. Jayne, M. R. Canagaratna, R. C. Miake-Lye, W. B. Knighton, J. Eng. Gas Turb. Power, 132, 06154 (14 pages), 2010.

Gas turbine engine emissions - Part II: Chemical properties of particulate matter, M. T. Timko, T. B. Onasch, M. J. Northway, J. T. Jayne, M. R. Canagaratna, S. C. Herndon, E. C. Wood, R. C. Miake-Lye, W. B. Knighton, J. Eng. Gas Turb. Power, 132, 061505 (15 pages), 2010.

Application of positive matrix factorization to on-road measurements for source apportionment of diesel- and gasoline-powered vehicle emissions in Mexico City, D. A. Thornhill, A. E. Williams, T. B. Onasch, E. Wood, S. C. Herndon, C. E. Kolb, W. B. Knighton, M. Zavala, L. T. Molina, L. C. Marr, Atmos. Chem. Phys. 10, 3629-3644, 2010.

Characterizing a quantum cascade tunable infrared laser differential absorption spectrometer (QC-TILDAS) for measurements of atmospheric ammonia, R. A. Ellis, J. G. Murphy, E. Pattey, R. van Haarlem, J. M. O'Brien, S. C. Herndon, Atmos. Meas. Tech. 3, 397-406, 2010.

Multicomponent breath analysis with infrared absorption using room-temperature quantum cascade lasers, J. H. Shorter, D. D. Nelson, J. Barry McManus, M. S. Zahniser, D. K. Milton, IEEE Sensors J., 10, 76-84, 2010.

Quantum cascade lasers in chemical physics, R. F. Curl, F. Capasso, C. Gmachl, A. A. Kosterev, B. McManus, R. Lewicki, M. Pusharsky, G. Wysocki, F. K. Tittel, Chem. Phys. Lett. 487, 1-18, 2010.

Long-term continuous sampling of 12CO2, 13CO2 and 12C18O16O in ambient air with a quantum cascade laser spectrometer, J. B. McManus, D. D. Nelson, M. S. Zahniser, Isot. Environ. Health Stu. 46, 49-63, 2010.

Adaptation of a proton transfer reaction mass spectrometer instrument to employ NO+ as reagent ion for the detection of 1,3-butadiene in the ambient atmosphere, W. B. Knighton, E. C. Fortner, S. C. Herndon, E. C. Wood, R. C. Miake-Lye, Rapid Commun. Mass Spectrom., 23, 3301-3308, 2009.

Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO2 retrievals during the MILAGRO field campaign, B.deFoy, N.A.Krotkov, N.Bei, S.C.Herndon, L.G.Huey, A.-P.Martnez, L.G.Ruiz-Surez, E.C.Wood, M.Zavala, L.T.Molina, Atmos. Chem. Phys. 9, 9599-9617, 2009.

High precision measurements of atmospheric concentrations and plant exchange rates of carbonyl sulfide using mid-IR quantum cascade laser, K. Stimler, D. Nelson, D. Yakir, Glob. Change Biol. 16, 2496-2503, 2010.

HCN detection with a proton transfer reaction mass spectrometer, W. B. Knighton, E. C. Fortner, A. J. Midley, A. A. Viggiano, S. C. Herndon, E. C. Wood, C. E. Kolb, Int. J. Mass. Spectrom. 283, 112-121, 2009.

Emissions of NOx SO2, CO, and HCHO from commercail marine shipping during Texas Air Quality Study (TEXAQS) 2006, E. J. Williams, B. M. Lerner, P. C. Herndon, M. S. Zahniser, JGR, 114, D21306, doi:10.1029/2009JD012094, 2009.

Measurements of volatile organic compounds during the 2006 TexAQS/GoMACCS campaign: Industrial influences, regional characteristics, and diurnal dependencies of the OH reactivity, J. B. Gilman, W. C. Kuster, P. D. Goldan, S. C. Herndon, M. S. Zahniser, S. C. Tucker, W. A. Brewer, B. M. Lerner, E. J. Williams, R. A. Harley, F. C. Fehsenfeld, C. Warneke, J. A. de Gouw, JGR, 114, D00F06, doi:10.1029/2008JD011525, 2009.

Aircraft hydrocarbon emissions at Oakland International Airport, S. C. Herndon, E. C. Wood, M. J. Northway, R. Miake-Lye, L. Thornhill, A. Beyersdorf, B. E. Anderson, R. Dowlin, W. Dodds, W. B. Knighton, Environ. Sci. Technol., 43, 1730-1736, 2009.

Comparison of emissions from on-road sources using a mobile laboratory under various driving and operational sampling modes, M.Zavala, S.C.Herndon, E.C.Wood, J.T.Jayne, D.D.Nelson, A.M.Trimborn, E.Dunlea, W.B.Knighton, A.Mendoza, D.T.Allen, C.E.Kolb, M.J.Molina, and L.T.Molina, Atmos. Chem. Phys.,9,1-14,2009.

ACRP Report 7: Aircraft and Airport-Related Hazardous Air Pollutants: Research Needs and Analysis, E. Wood, S. Herndon, R. C. Miake-Lye, D. Nelson, M. Seeley, 65p. (2008). Airport Cooperative Research Program, Transportation Research Board, Washington, DC

Correlation of secondary organic aerosol with odd oxygen in Mexico City, S. C. Herndon, T. B. Onasch, E. C. Wood, J. H. Kroll, M. R. Canagaratna, J. T. Jayne, M. A. Zavala, W. B. Knighton, C. Mazzoleni, M. K. Dubey, I. M. Ulbrich, J. L. Jimenez, R. Seila, J. A. de Gouw, B. de Foy, J. Fast, L. T. Molina, C. E. Kolb, doi:10.1029/2008GL034058, 2008.

Spatial and temporal variability of particulate polycyclic aromatic hydrocarbons in Mexico City, D. A. Thornhill, B. de Foy, S. C. Herndon, T. B. Onasch, E. C. Wood, M. Zavala, L. T. Molina, J. S. Gaffney, N. A. Marley, L. C. Marr1, Atmos. Chem. Phys., 8, 3093-3105, 2008.

High precision and continuous field measurements of 13C and 18O in carbon dioxide with a cryogen-free QCLAS, B. Tuzson, J. Mohn, M. J. Zeeman, R. A. Werner, W. Eugster, M. S. Zahniser, D. D. Nelson, J. B. McManus, L. Emmenegger, Appl. Phys. B, DOI: 10.1007/s00340-008-3085-4, 2008.

Pulsed quantum cascade laser instrument with compact design for rapid, high sensitivity measurements of trace gases in air, J. B. McManus, J. H. Shorter, D. D. Nelson, M. S. Zahniser, D. E. Glenn, R. M. McGovern, Appl. Phys. B., 92, 387-392, 2008.

Development of negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS) for the measurement of gas-phase organic acids in the atmosphere, P. Veres, J. M. Roberts, C. Warneke, D. Welsh-Bon, M. Zahniser, S. Herndon, R. Fall, J. de Gouw, Int. J. Mass Spectrom., 274, 48-55, 2008.

New method for isotopic ratio measurements of atmospheric carbon dioxide using a 4.3 m pulsed quantum cascade laser, D. D. Nelson, J. B. McManus, S. C. Herndon, M. S. Zahniser, B. Tuzson, L. Emmenegger, Appl. Phys. B, 90, 301-310, 2008. Special Issue: 6th International Conference on tunable laser spectroscopy.

Quantum cascade laser based spectrometer for in situ stable carbon dioxide isotope measurements, B. Tuzson, M. J. Zeeman, M. S. Zahniser, L. Emmenegger, Infrared Physics & Technology, 51, (1), 198-206, 2008.

Suitability of quantum cascade laser spectroscopy for CH4 and N2O eddy covariance flux measurements, P. S. Kroon, A. Hensen, H. J. J. Jonker, M. S. Zahniser, W. H. van't Veen, A. T. Vermeulen, Biogeosciences, 4, Special issue, 715-728, 2007.

Laboratory evaluation of an aldehyde scrubber system specifically for the detection of acrolein, W. B. Knighton, S. C. Herndon, J. H. Shorter, R. C. Miake-Lye, M. S. Zahniser, K. Akiyama, A. Shimono, K. Kitasaka, H. Shimajiri, K. Sugihara, J. Air & Waste Manage. Assoc. 57,, 1370-1378, 2007.

Tunable diode laser absorption spectroscopy study of CH3CH2OD/D2O binary condensation in a supersonic Laval nozzle, S. Tanimura, B. E. Wyslouzil, M. S. Zahniser, J. H. Shorter, D. D. Nelson, J. B. McManus, J. Chem.Phys. 127, 034305 (13), 2007.

Towards realization of reactive gas amount of substance standards through spectroscopic measurements, P. M. Chu, D. D. Nelson, Jr., M. S. Zahniser, J. B. McManus, Q. Shi, J. C. Travis, IEEE T. Instrum. Meas., 56, 305-308, 2007.

Evaluation of nitrogen dioxide chemiluminescence monitors in a polluted urban environment, E. J. Dunlea, S. C. Herndon, D. D. Nelson, R. M. Volkamer, F. San Martini, P. M. Sheehy, M. S. Zahniser, J. H. Shorter, J. C. Wormhoudt, B. K. Lamb, E. J. Allwine, J. S. Gaffney, N. A. Marley, M. Grutter, C. Marquez, S. Blanco, B. Cardenas, A. Retama, C. R. Ramos Villegas, C. E. Kolb, L. T. Molina1, M. J. Molina, Atmos. Chem. Phys., 7, 26912704, 2007.

Airborne measurements of HCHO and HCOOH during the New England Air Quality Study 2004 using a pulsed quantum cascade laser spectrometer, S.C. Herndon, M.S. Zahniser, D.D. Nelson Jr., J. Shorter, J.B. McManus, R. Jimnez, C. Warneke, J.A. DeGouw, J. Geophys. Res., 112, D10S03, doi:10.1029/2006JD007600, 2007.

Atmospheric & Environmental Chemistry | Aerodyne Research ...

Anyone have objective data on the effectiveness of the …

Stell Cell Research | Posted by admin
Feb 09 2019

@StemCellPioneers I think you raise an interesting argument, but not for the reasons you list. The FDA is at least trying to base decisions on ACTUAL DATA, whereas there IS NO VERIFIABLE DATA on the therapeutic use of stem cells. What the FDA is saying is that the study is limited, and thus should be interpreted with caution. Therefore, they are being CONSISTENT. Flawed or limited data does not equal legitimate data on which to base decisions. So yes, if a study is limited, according to the FDA, then it is acceptable that a potentially dangerous drug should be continued to be given to children.

I dont have access to this particular study from home, but I can already tell you that retrospective case control studies can have significant problems with bias and confounding. See, this study states in the methods The primary exposure measure was the presence of amphetamine, dextroamphetamine, methamphetamine, or methylphenidate according to informant reports or as noted in medical examiner records, toxicology results, or death certificates. Now, even without reading the paper, which I will, I can already identify a potential source of bias. Kids who experienced sudden death were probably a lot more likely to have an autopsy, where drugs would be found by toxicology, whereas the kids who died in auto accidents probably were less likely to have autopsies, and the investigators likely relied on interviews with the family (less reliable). Thus, I predict that when I read the study tomorrow, I will find more autopsies in the sudden death group, and thus a greater association of sudden death with stimulants (because they were found more frequently by a better method). We shall see.

In any event, at least the FDA is weighing DATA, pros and cons, etc. There have been many cases of the FDA pulling medications and-or issuing black box warnings (for example, the diet drug fen-phen). This is how the system works. No drug is perfect, and as such needs to be approved through prospective studies, and constantly reviewed via aftermarket analysis. If more proof accumulates indicating that stimulants are harmful in ADHD, you can be sure the FDA will pull the drugs from the market. In contrast, the stem cell pioneers are just pushing forward, without so much as a hint that there could be some benefit (save lots and lots of anecdotal stories, which could easily be attributed to placebo affects).

I will say this again (perhaps for the 5th or 6th time). As a physician-scientist I truly believe in the promise of stem cells. I really, really do. However, no one will ever know if stem cell treatments are effective if they arent studied in rigorous, well-controlled clinical trials. This is true of all new treatments. And I would ask, why are the purveyors of this treatment not the leaders in the field of stem cell research? You talk about reputable stem cell clinic or doctor, but I consider that a misnomer. No reputable doctor would perform these infusions without it being part of a clinical trial or as an already verified procedure. Furthermore, this thread has piqued my interest in this area, and Ive been doing a lot of web research over the past few days. Interestingly, quite a few of the doctors and clinics discussed on your very site have had major legal and ethical issues (including doctors that are heavily promoted), which argues against them being reputable. The doctors who run these clinics may claim to be scientists, but in reality, the bulk of cutting edge stem cell work is going on in major academic hospitals, not small, private clinics run by doctors with little to no scientific training.

Finally, I really hope you find what you are looking for in stem cell infusions. Neither I nor any doctor wants patients to suffer needlessly, but apparently the majority of the medical community views the current status of stem cell treatments to be in its infancy. Many of us are concerned that the quixotic pursuit of highly experimental stem cell treatments could be detrimental on an emotional, financial, and possibly biologic level.

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Anyone have objective data on the effectiveness of the ...

Learn Zone – VetCompass – Royal Veterinary College, RVC

Stell Cell Research | Posted by admin
Feb 09 2019

Veterinary Epidemiology in Practice - The VetCompass Programme

Dr. Dan O'Neill (VetCompass, RVC)

In this e-lecture, recorded as part of the VET Talks series hosted by the RVC, Dr Dan O'Neill gives an overview of practice-based veterinary epidemiological research and describes the important role of VetCompass in pushing the boundaries of this exciting new field.

Dr. Dan O'Neill (VetCompass, RVC) & Dr. Katy Evans (University of Nottingham) British Small Animal Veterinary Association Annual Congress, 2015

This talk was delivered at BSAVA Congress 2015 and addresses the importance of generating high quality evidence to inform decision-making for the improvement of canine welfare. Dr. Dan ONeill and Dr. Katy Evans discuss the importance of evidence-based veterinary advice when aiming to improve dog health at a population level, highlighting how large-scale, ongoing health surveillance projects such as VetCompass are vital in providing relevant, representative findings for practical use by clinicians.

This audio recording is shared by kind permission of the UK Kennel Club.

Dr. Dan O'Neill (VetCompass, RVC) & Aimee Llewellyn (Geneticist & Health Information Manager, UK Kennel Club)British Small Animal Veterinary Association Annual Congress, 2015

This talk was delivered as part of the first ever BSAVA lecture stream on Practical aspects of dog breeding. Dr. Dan ONeill and Aimee Llewellyn (of the Royal Veterinary College & UK Kennel Club respectively) presented information on the practical approaches veterinary practices can take to improve the advice they give to breeder clients. Bothspeakers emphasised the vital role that veterinary practitioners can play in improving dog health at a population level and highlighted the importance of large-scale, ongoing health surveillance projects such as VetCompass.

This audio recording is shared by kind permission of the UK Kennel Club.

Discussinghowwe canuse the information contained in veterinary clinical records to better understand pain-related welfare in companion animals

A short video about VetCompass with examples of evidence generated, with musical accompaniment (no speaker)

Information on the expected lifespan and causes of death in dogs in England based on a VetCompass Programme study

Find out how common epilepsy is in dogs and which breeds are affected

McGreevy, PD, Wilson BJ, Mansfield, CS.Church DB, Brodbelt DC, Dhand, N,Soares Magalhaes, RJ and O'Neill DG. (2018)Canine Genetics and Epidemiology

O'Neill DG, Baral L, Church DB, Brodbelt DC and Packer RMA (2018) Canine Genetics and Epidemiology 5:3.

O'Neill DG, Darwent EC, Church DB and Brodbelt DC (2017) Canine Genetics and Epidemiology 4:15

O'Neill DG, Yin Seah W, Church DB and Brodbelt DC (2017) Canine Genetics and Epidemiology 4:13

O'Neill DG, Coulson NR, Church DB and Brodbelt DC (2017) Canine Genetics and Epidemiology 4:7

O'Neill DG, Darwent EC, Church DB andBrodbelt DC (2016) Canine Genetics and Epidemiology, 3(1):1-12.

Summers JF, ONeill DG, Church DB, Thomson PC, McGreevy PD and Brodbelt DC. (2015) Canine Genetics and Epidemiology.

Boyd, C., Jarvis, S., McGreevy, P., Heath, S., Church, D., Brodbelt, D., and O'Neill, DG. (2018)Animal Welfare

Conroy, M., O'Neill, DG., Boag, A., Church, DB., and Brodbelt, DC. (2018). Journal of Small Animal Practice.

McDonald JL, Cleasby LR, Brodblet DC, Church DB and O'Neill DG (2017) Journal of Small Animal Practice DOI: 10.1111/jsap.12716, n/a-n/a. (Early view)

O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC (2014) Veterinary Journal.

O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC (2014) Journal of Feline Medicine and Surgery.

O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC(2014) PLoS One,9(3).

O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC(2013) The Veterinary Journal,198,638-643.

Mattin MJ, Boswood A, Church DB, Brodbelt DC (2018) Journal of Veterinary Internal Medicine

Mattin MJ, Boswood A, Church DB, McGreevy PD, O'Neill DG, Thomson PC, Brodbelt DC. (2015; Epub ahead of print) Preventive Veterinary Medicine

Mattin MJ, Boswood A, Church DB, Lpez-Alvarez J, McGreevy PD, O'Neill DG, Thomson PC, Brodbelt DC. (2015) Journal of Veterinary Internal Medicine

O'Neill DG, Gostelow R, Orme C, Church D., Niessen SJM, Verheyen K & Brodbelt DC (2016) Journal of Veterinary Internal Medicine

O'Neill DG, Scudder C, Faire JM, Church DB, McGreevy PD, Thomson PC andBrodbelt DC(2016)Journal of Small Animal Practice2016

Mattin MJ, O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC (2014) The Veterinary Record,174(14), 349.

Stephens MJ, O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC (2014) The Veterinary Record.

O'Neill DG, Case J, Boag AK, Church DB, McGreevy PD, Thomson PC & Brodbelt DC (2017) Journal of Small Animal Practice, DOI: 10.1111/jsap.12723, n/a-n/a

Erlen A, Potschka H, Volk HA, Sauter-Louis C, O'Neill DG, (2018) Journal of Veterinary Internal Medicine.

Kearsley-Fleet L, O'Neill DG, Volk HA, Chursh DB, Brodbelt DC (2013) The Veterinary Record;30;172

O'Neill, DG., Corah, CH., Church, DB., Brodbelt, DC., and Rutherford, L. (2018).Canine Genetics and Epidemiology

Shoop SJ,Marlow S,Church DB,English K,McGreevy PD,Stell AJ,Thomson PC,O'Neill DGandBrodbelt DC (2014) Canine Genetics and Epidemiology.

O'Neill, D.G., Lee, M.M, Brodbelt, D.C., Church, D.B. & Sanchez, R.F. (2017) Canine Genetics and Epidemiology 4:5

Anderson KL, O'Neill DG, Brodbelt DC, Church DB, Meeson RL, Sargan D, Summers JF, Zulch H & Collins LM(2018)Scientific Reports

O'Neill DG, Meeson RL, Sheridan A, Church DB andBrodbelt DC (2016) Canine Genetics and Epidemiology

Taylor-Brown FE, Meeson RL, Brodbelt DC, Church DB, McGreevy PD, Thomson PC & O'Neill DG. (2015) Veterinary Surgery

O'Neill D, Jackson C, Guy J, Church D, McGreevy P, Thomson P. & Brodbelt D.(2015) Canine Genetics and Epidemiology

O'Neill, D.G., O'Sullivan, A.M., Manson, E.A., Church, D.B., McGreevy, P.D., Boag, A.K. and Brodbelt, D.C. (2019) Veterinary Record

Stevens K.B., O'Neill D.G., Jepson R., Holm L.P., Walker D.J., andCardwell J.M.(2018) Veterinary Record

Hall, J.L., Owen, L., Riddell, A., Church, D.B., Brodbelt, D.C., and O'Neill D.G., (2018)Journal of Small Animal Practice.

O'Neill D.G., O'Sullivan AM, Manson EA, Church DB, Boag AK, McGreevy PD and Brodbelt D.C. and (2017)VeterinaryRecordDOI:10.1136/vr.104108 DOI:10.1111/jsap.12731

O'Neill D.G., Riddell A., Church D.B., Owen L., Brodbelt D.C. and Hall J.L. (2017) Journal of Small Animal Practice DOI:10.1111/jsap.12731

O'Neill DG, Elliott J, Church DB, McGreevy PD, Thomson PC, Brodbelt DC(2013) Journal of Veterinary Internal Medicine;27(4):814-21

Buckland, E., O'Neill, D., Summers, J., Mateus, A., Church, D., Redmond, L. and Brodbelt, D. Veterinary Record (2016) doi:10.1136/vr.103830

Summers JF, Hendricks A, Brodbelt DC (2014) BMC Veterinary Research.

O'Neill DG, Hendricks A, Summers JF,Brodbelt DC(2012) J Small Anim Pract;53(4): 217-22

Muellner, P., Muellner, U., Gates, M. C., Pearce, T., Ahlstrom, C., O'Neill, D., Brodblet, D. & Cave, N. J. (2016) Frontiers in Veterinary Science, 3.

O'Neill DG, Church DB, McGreevy PD, Thomson PC, Brodbelt DC (2014) Canine Genetics and Epidemiology,1:2.

Hoffman, J.M., Creevy, K.E., Franks, A., O'Neill, D.G. and Promislow, D.E.L. (2018) Aging Cell.

Hoffman, J.M., O'Neill, D.G., Creevy, K.E., & Austad, S.N.(2018)The Journals of Gerontology: Series A, 73, 150-156.

Jin, K., Hoffman, J.M., Creevy, K.E., O'Neill, D.G. and Promislow, D.E.L. (2016) Pathobiology of Aging and Age-related Diseases6:33276

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Learn Zone - VetCompass - Royal Veterinary College, RVC

Retinitis Pigmentosa – The Foundation Fighting Blindness

Stell Cell Research | Posted by admin
Feb 06 2019


Retinitis pigmentosa (RP) describes a group of genetic disorders that damage light-sensitive cells in the retina, leading to gradual vision loss over time as the cells die off. While the condition is classified as a rare disease, it is one of the most common inherited diseases of the retina, affecting between 1 in 3500 to 1 in 4000 Canadians.[1]RP is often referred to as an inherited retinal disease, meaning that it is passed along genetic lines and inherited from ones parents. Though it is usually diagnosed during childhood or adolescence, a minority of patients report symptoms later in life.

Specialized cells called photoreceptors are responsible for absorbing light and translating it into signals that are interpreted by the brainit is these essential cells that gradually die off as a result of RP. The cells come in two varieties: rod cells and cone cells. Rod photoreceptors are responsible for peripheral and night vision, while cone photoreceptors are responsible for central, high-acuity vision as well as detail and colour. Since it is the rod cells that are first damaged by RP, peripheral and night vision are affected during the early stages of the disease, followed by a narrowing of the visual field, often referred to as a progressive form of tunnel vision. The death of rod cells eventually affects the cone cells as well, leading to the loss of central vision and often resulting, during the later stages of the disease, in near or total blindness. The length of this process varies from individual to individual.

RP was originally considered a single disease, but after decades of researchincluding research funded by the FFBwe now know that there are several forms of RP, and that these forms involve mutations in any one of more than 64 different genes. The gene or genes affected determine the disease type and symptoms.

There are several different ways that RP can be inherited, which is usually described as the inheritance pattern. The different RP inheritance patterns include: autosomal dominant, autosomal recessive, and x-linked recessive. A genetic counsellor can talk with you about your family history and determine which of these patterns is associated with your vision loss. With this information, the genetic counsellor may be able to tell you more about how your condition will progress, and give you and your family information about the risks of vision loss for other family members. To learn more about genetic testing for RP, please consult the FFB resource Everything You Need to Know about Genetic Testing.

Typically, each person with RP only has damage in one pair of genes. Scientists have now identified more than 64 genes that can have mutations that cause RP. It is likely that mutations in more than 100 different genes will eventually be identified. Because so many RP-causing gene mutations are still unknown, there is about a 50:50 chance that genetic testing will provide a definitive result. Given your family history and the inheritance pattern of your RP, your genetic counsellor will be able to advise you about the likelihood that a genetic test will provide a definitive result.

Different genetic mutations can damage the retina or impair its function in different ways; for example, some mutations affect how the retina processes nutrients, while others damage the photoreceptors. Its important to identify the specific gene and mutation, because many treatments being developed for RP will be for particular genetic types.

Content on this page was written by Dr. Chad Andrews and Dr. Mary Sunderland, and was most recently updated on August 23, 2018. An earlier version of the content was approved by Dr. Jane Green and Dr. Bill Stell.

The most common early symptom of RP is difficultly seeing at night and in low-light conditionsthis is called nyctalopia or night blindness. The loss of peripheral vision is also a common first symptom, and is often experienced alongside nyctalopia. As RP progresses, peripheral vision slowly diminishes, resulting in a narrow field of view or tunnel vision. By age 40, many people with RP are legally blind, with a severely constricted field of vision, although many may retain the ability to read and recognize faces. Uncomfortable sensitivity to light and glare is common, as is photopsia (seeing flashes of light or shimmering). RP can also cause a loss of visual acuity (the ability to see clearly), but the onset is more variable. Some patients retain normal visual acuity, even when their vision is reduced to a small central island; others lose acuity much earlier in the course of disease. Eventually, however, most people with RP will begin to lose central vision and some will lose all light perception.

An ophthalmologist may suspect RP on the basis of a persons symptoms and the findings of a simple eye examination. Two tests are used to clarify the diagnosis:

Currently, there is only a single approved treatment for a very rare form of RP on the market in the United States: a gene therapy called Luxturna, which can halt vision loss and even restore some sight in individuals with a biallelic mutation of their RPE65 gene (manifesting as either RP or Leber congenital amaurosis). Though the number of patients with this mutation is small, the medical effectiveness of Luxturna and its materialization as a pharmaceutical product demonstrate that there is significant potential for gene therapy to treat other forms of RP in the future.

Read Our Story About The Approval of Luxturna

Clinical trials are essential to the scientific process of developing new treatments: they test the viability and safety of experimental drugs and techniques, called interventions, on human beings. While there is no guarantee that enrolling in a clinical trial will provide any medical benefit, some patients do experience positive results after receiving an experimental therapy.

Read Our Clinical Trials Guide

The website is a centralized database of clinical trials that are offered globally. But as the disclaimer on the sites home page states, there is no guarantee that a listed trial has been evaluated or approvedthe National Institutes of Health runs the site but does not vet its content. This means that there could be bogus or dangerous trials listed that are preying on patients. It is essential that you discuss a clinical trial with your ophthalmologist before enrolling, and that you pay close attention to enrollment criteria.

If you are interested in exploring what is available on the site you can click on the button below, which will take you to and initiate a search for trials relevant for patients living with RP.

CLINICAL TRIALS FOR Retinitis Pigmentosa

For individuals living with an inherited retinal disease (a disease caused by a genetic mutation), participation in a clinical trial could be a logical next-step (for a description of clinical trials, see above). But in Canada there is no centralized, guided mechanism for enrolling in a trial; with this in mind, the Foundation Fighting Blindness has developed a secure medical database of Canadian patients living with inherited retinal diseases: we call it the Patient Registry.

By enrolling in the Patient Registry, your information will become a part of this essential Canadian database that can be used to help connect you to a relevant clinical trial. The availability of relevant trials depends on a number of factors, so this tool provides no guarantees, but signing onto it will put you in a position to be connected to something appropriate. It is also a way of standing up and being counted: the more individuals enrolled in the Patient Registry, the better our chances of showing policymakers that there is a significant need for new treatments for inherited retinal diseases. The Patient Registry also helps to drive more sight-saving research!

You can begin the process of enrolling in the Patient Registry by clicking the button below.

Patient Registry Enrollment

The Foundation Fighting Blindness is committed to advancing the most promising sight-saving research, and has invested over $33 million into cutting-edge science since the organization was founded. Recognizing that science is tied to policy frameworks, the Foundation is also actively involved in health policy activities across Canada.

Many research groups are working to develop treatments and cures for RP. Experimental treatments can be divided into three broad categories:

Protective therapies aim to stop (or at least slow) the damage caused by genetic mutations. Often protective therapies are not specific to one mutation, but may benefit people with many types of RP. These include treatments to stop the process of photoreceptor death (apoptosis), as well as cell-derived therapies that aim to help photoreceptors survive.

Some protective therapies aim specifically to prevent the death of cone cells in RP and thus, the loss of central vision in later stages of the disease.

Corrective therapies aim to reverse the underlying genetic defect that causes vision loss. If these therapies are successful they might prevent a person who is treated when first diagnosed, from ever developing vision loss. Corrective therapies might also help slow the disease in people whose vision has already been affected, especially in the earlier stages. The corrective therapies being developed now are specific to certain forms of recessively inherited RP. Gene therapies, which replace a non-functioning gene, are one type of corrective therapy. Clinical trials of gene therapies for several types of RP are underway, and the results so far are encouraging.

Sight-restoring therapies are also a growing area of research success. These therapies are intended for people who have already lost all, or much, of their vision. Stem cell therapies aim to replace the retinas lost photoreceptors. There are promising early results with stem cell trials involving other retinal degenerative diseases; trials with RP are on the horizon. Retinal prosthetics, such as the Arugus II or Bionic Eye, use computer technology to generate vision. The Foundation Fighting Blindness helped to support the first Canadian trial of the Argus II and continues to work closely with health policy experts across Canada to ensure that patients who could benefit from the Argus II device have access to this innovative treatment. Drug and gene therapies are also being developed that may give non-photoreceptor nerve cells in the retina the capacity to sense light.

Thanks to our generous donors, we are funding ground-breaking research in these areas. Click on the button below to review the full list of FFB-funded projects:


On the right side of this webpage, you will find an updating list of stories that detail new research and health policy developments relevant for individuals affected by RP.

The page you are now on provides information on RP, but the Foundation Fighting Blindness has developed additional resources that can be helpful in plotting an optimal path through vision care. Below is a list of such resources, including information on genetic testing, clinical trials, Vision Quest (the FFBs in-person educational events), and more. The list will update as new resources are added.

Must-Read Resources Vision Quest Educational Series

We know that helpful resources related to your eye disease can be difficult to find. Vision care in Canada entails a complex web of services, programs, and instructions, and little of it is centralized. The information on this site represents our attempt at providing a comprehensive, centralized resource that offers guidance and information specific to your eye disease. Our goal is to help you find your optimal path through vision care in Canada, which is why we call this initiative Vision Care Pathways.

December 12th, 2018 by FFB Canada

Right now, over 1 million Canadians are living with blinding eye diseases and as vision fades, so too can hope. To date, donors of the Foundation Fighting Blindness (FFB) have contributed more than $32 million for vision research. And now, until the end of 2018, a generous supporter will match your gift up to a

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November 13th, 2018 by FFB Canada

On Saturday, October 20, 2018, family and friends of the Celebres came together in support of one very special little boy. Nicholas Celebre was born with Usher syndrome,a condition that causes deaf-blindness and often balance issues. Born profoundly deaf, he was fortunate enough to get cochlear implants when he was 12 months old. He also

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November 13th, 2018 by FFB Canada

Guest-written by Deborah Scott. Our daughter, Olivia was 5 years old when she was diagnosed with a blinding eye disease called retinitis pigmentosa (RP). It was difficult for us to comprehend what that diagnosis really meant. As a parent, you never get over the impact of learning that there is so much more to vision

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Retinitis Pigmentosa - The Foundation Fighting Blindness