266 results on '"Lindsay, David"'
Search Results
2. Effective Confidence Region Prediction Using Probability Forecasters
- Author
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Lindsay, David, Lindsay, Sian, Lindsay, David, and Lindsay, Sian
- Abstract
Confidence region prediction is a practically useful extension to the commonly studied pattern recognition problem. Instead of predicting a single label, the constraint is relaxed to allow prediction of a subset of labels given a desired confidence level 1-delta. Ideally, effective region predictions should be (1) well calibrated - predictive regions at confidence level 1-delta should err with relative frequency at most delta and (2) be as narrow (or certain) as possible. We present a simple technique to generate confidence region predictions from conditional probability estimates (probability forecasts). We use this 'conversion' technique to generate confidence region predictions from probability forecasts output by standard machine learning algorithms when tested on 15 multi-class datasets. Our results show that approximately 44% of experiments demonstrate well-calibrated confidence region predictions, with the K-Nearest Neighbour algorithm tending to perform consistently well across all data. Our results illustrate the practical benefits of effective confidence region prediction with respect to medical diagnostics, where guarantees of capturing the true disease label can be given., Comment: 10 pages, originally posted in 2005
- Published
- 2024
- Full Text
- View/download PDF
3. Learning from String Sequences
- Author
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Lindsay, David, Lindsay, Sian, Lindsay, David, and Lindsay, Sian
- Abstract
The Universal Similarity Metric (USM) has been demonstrated to give practically useful measures of "similarity" between sequence data. Here we have used the USM as an alternative distance metric in a K-Nearest Neighbours (K-NN) learner to allow effective pattern recognition of variable length sequence data. We compare this USM approach with the commonly used string-to-word vector approach. Our experiments have used two data sets of divergent domains: (1) spam email filtering and (2) protein subcellular localization. Our results with this data reveal that the USM-based K-NN learner (1) gives predictions with higher classification accuracy than those output by techniques that use the string-to-word vector approach, and (2) can be used to generate reliable probability forecasts., Comment: 10 pages, 1 figure, 4 tables, Technical Report
- Published
- 2024
4. Three Essays in Macro-Finance.
- Author
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Lindsay, David Ciaran, Atkeson, Andrew G.1, Weill, Pierre-Olivier, Lindsay, David Ciaran, Lindsay, David Ciaran, Atkeson, Andrew G.1, Weill, Pierre-Olivier, and Lindsay, David Ciaran
- Abstract
In Chapter 1, I use a structural approach, to quantify the effect of land-use regulations on different age and education groups. I estimate a dynamic spatial structural equilibrium model of household location choice, local housing supply, and amenity supply. I show that in the long-run, removing land-use restrictions benefits all household groups and increases aggregate consumption by 7.1%. These consumption gains vary across households, less educated and younger households see increases in consumption about twice as large as more educated or older households. In contrast, in the short-run, removing land-use regulations reduces the consumption of older-richer homeowners while increasing the consumption of younger renters. In a counterfactual 1990-2019 transition, abolishing land-use regulations reduces the consumption of households born before the mid-1960s, while increasing consumption of more recent generations. In Chapter 2, co-authored with Mahyar Kargar, Benjamin Lester, Shuo Liu, Pierre-Olivier Weill, Diego Zuniga, we study liquidity conditions in the corporate bond market during the COVID-19 pandemic. We document that the cost of trading immediately via risky-principal trades dramatically increased at the height of the sell-off, forcing customers to shift toward slower agency trades. Exploiting eligibility requirements, we show that the Federal Reserve’s corporate credit facilities have had a positive effect on market liquidity. A structural estimation reveals that customers’ willingness to pay for immediacy increased by about 200 bps per dollar of transaction, but quickly subsided after the Fed announced its interventions. Dealers’ marginal cost also increased substantially but did not fully subside.In Chapter 3, co-authored with Diego Zuniga, we study inter-dealer trading patterns in the US corporate bond market. We document that dealers trade with only a small group of other dealers and that this group of dealers is highly persistent over time. We show tha
- Published
- 2022
5. Three Essays in Macro-Finance.
- Author
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Lindsay, David Ciaran, Atkeson, Andrew G.1, Weill, Pierre-Olivier, Lindsay, David Ciaran, Lindsay, David Ciaran, Atkeson, Andrew G.1, Weill, Pierre-Olivier, and Lindsay, David Ciaran
- Abstract
In Chapter 1, I use a structural approach, to quantify the effect of land-use regulations on different age and education groups. I estimate a dynamic spatial structural equilibrium model of household location choice, local housing supply, and amenity supply. I show that in the long-run, removing land-use restrictions benefits all household groups and increases aggregate consumption by 7.1%. These consumption gains vary across households, less educated and younger households see increases in consumption about twice as large as more educated or older households. In contrast, in the short-run, removing land-use regulations reduces the consumption of older-richer homeowners while increasing the consumption of younger renters. In a counterfactual 1990-2019 transition, abolishing land-use regulations reduces the consumption of households born before the mid-1960s, while increasing consumption of more recent generations. In Chapter 2, co-authored with Mahyar Kargar, Benjamin Lester, Shuo Liu, Pierre-Olivier Weill, Diego Zuniga, we study liquidity conditions in the corporate bond market during the COVID-19 pandemic. We document that the cost of trading immediately via risky-principal trades dramatically increased at the height of the sell-off, forcing customers to shift toward slower agency trades. Exploiting eligibility requirements, we show that the Federal Reserve’s corporate credit facilities have had a positive effect on market liquidity. A structural estimation reveals that customers’ willingness to pay for immediacy increased by about 200 bps per dollar of transaction, but quickly subsided after the Fed announced its interventions. Dealers’ marginal cost also increased substantially but did not fully subside.In Chapter 3, co-authored with Diego Zuniga, we study inter-dealer trading patterns in the US corporate bond market. We document that dealers trade with only a small group of other dealers and that this group of dealers is highly persistent over time. We show tha
- Published
- 2022
6. Submission in Response to Australian Government, Department of Home Afffairs, Strengthening Australia’s Cybersecurity Regulations and Incentives – Discussion Paper
- Author
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Fraser, Henry, Lindsay, David, Wright, Evana, Wilkinson, Genevieve, Collings, Neva, Fraser, Henry, Lindsay, David, Wright, Evana, Wilkinson, Genevieve, and Collings, Neva
- Abstract
This was a submission responding to the Dept of Home Affaris' discussion paper on regulating cybersecurity
- Published
- 2022
7. Gamogony of Sarcocystis Strixi in Mammalian Cell Cultures
- Author
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Lindsay, David S., Verma, S. K., Dubey, Jitender P., Scott, David, von Dohlen, Alexa Rosypal, Lindsay, David S., Verma, S. K., Dubey, Jitender P., Scott, David, and von Dohlen, Alexa Rosypal
- Abstract
We are interested in the disease ecology of Sarcocystis species that infect birds of prey as definitive and intermediate hosts. The present study was done to test our hypothesis that a laboratory model can be developed for sarcocystis infection in mammals using gamma interferon gene knockout (KO) mice as a source of Sarcocystis strixi bradyzoites and mammalian cell cultures as a source of sporulated S. strixi oocysts. Sporocysts of S. strixi from a naturally infected barred owl (Strix varia) were fed to KO mice to produce sarcocysts, and the enclosed bradyzoites were obtained by acid-pepsin digestion of abdominal and thigh muscles. Bradyzoites, metrocytes, and an unusual spherical stage were seen in digest before the inoculation of host cells. The spherical stages stained dark with Giemsa stain, but no nucleus was observed, and they were seen free and associated with the concave portion of some bradyzoites. Examination of infected cell cultures demonstrated that macrogamonts and microgamonts were present at 24 hr post-inoculation. Since sporulated oocysts were not observed, we had to reject our current hypothesis.
- Published
- 2021
- Full Text
- View/download PDF
8. Gamogony of Sarcocystis Strixi in Mammalian Cell Cultures
- Author
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Lindsay, David S., Verma, S. K., Dubey, Jitender P., Scott, David, von Dohlen, Alexa Rosypal, Lindsay, David S., Verma, S. K., Dubey, Jitender P., Scott, David, and von Dohlen, Alexa Rosypal
- Abstract
We are interested in the disease ecology of Sarcocystis species that infect birds of prey as definitive and intermediate hosts. The present study was done to test our hypothesis that a laboratory model can be developed for sarcocystis infection in mammals using gamma interferon gene knockout (KO) mice as a source of Sarcocystis strixi bradyzoites and mammalian cell cultures as a source of sporulated S. strixi oocysts. Sporocysts of S. strixi from a naturally infected barred owl (Strix varia) were fed to KO mice to produce sarcocysts, and the enclosed bradyzoites were obtained by acid-pepsin digestion of abdominal and thigh muscles. Bradyzoites, metrocytes, and an unusual spherical stage were seen in digest before the inoculation of host cells. The spherical stages stained dark with Giemsa stain, but no nucleus was observed, and they were seen free and associated with the concave portion of some bradyzoites. Examination of infected cell cultures demonstrated that macrogamonts and microgamonts were present at 24 hr post-inoculation. Since sporulated oocysts were not observed, we had to reject our current hypothesis.
- Published
- 2021
9. Toxoplasmosis in wild and domestic animals
- Author
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Lindsay, David S., Dubey, Jitender P., Lindsay, David S., and Dubey, Jitender P.
- Published
- 2020
- Full Text
- View/download PDF
10. Neosporosis, Toxoplasmosis, and Sarcocystosis in Ruminants: An Update
- Author
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Lindsay, David S., Dubey, Jitender P., Lindsay, David S., and Dubey, Jitender P.
- Abstract
Neospora caninum, Toxoplasma gondii, and Sarcocystis spp. are related Apicomplexan parasites that have 2 hosts in their life cycles. The definitive hosts excrete unsporulated (Neospora caninum, T gondii) or sporulated (Sarcocystis spp.) oocysts in their feces after ingesting tissue cysts from the tissues of ruminant intermediate hosts. These coccidians can cause abortion and neonatal mortality in ruminants. T gondii and Sarcocystis hominis (from cattle) are zoonotic. This article reviews information on the etiology, life cycle, diagnosis, control and prevention of these parasites and the diseases they cause in ruminants.
- Published
- 2020
- Full Text
- View/download PDF
11. Perils of speed dating: an Australian success story in Chinese outbound tourism
- Author
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Lindsay, David, Kriz, Anton, Johns, Raechel, Keating, Byron, Lindsay, David, Kriz, Anton, Johns, Raechel, and Keating, Byron
- Abstract
This paper provides insights and lessons about how Western tourism operators can build and maintain business-to-business relationships with Chinese tourism providers. The case analyses how Tangalooma Island Resort Pty Ltd approached the challenge of developing business networks and how they have sustained this activity for over a decade to become a major destination for Chinese visitors to Australia. While there is no shortage of research on the Chinese notion of guanxi, this study uses a novel multi-dimensional cultural intelligence perspective to synthesise Chinese and Australian views on the drivers of long-term commercial success. The frameworks and insights provided make a valuable and timely contribution to our understanding of how Western firms can approach China tourism opportunities, and importantly, provide lessons on the nuances of effective relationship development between Western and Chinese individuals and firms. This critical single case study highlights the importance of business negotiation and need for deepening cultural logic with appropriate pacing by key protagonists in the Western firm. Nurturing and growing interpersonal cultural skills is fundamental and helps build inter-firm bonds, resource ties and activity links. This is discussed using the actors–activities–resources model promoted within the context of industrial marketing and purchasing. Future research could extend the findings through additional case studies, or further empirical validation.
- Published
- 2020
12. Neosporosis, Toxoplasmosis, and Sarcocystosis in Ruminants: An Update
- Author
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Biomedical Sciences and Pathobiology, Lindsay, David S., Dubey, Jitender P., Biomedical Sciences and Pathobiology, Lindsay, David S., and Dubey, Jitender P.
- Abstract
Neospora caninum, Toxoplasma gondii, and Sarcocystis spp. are related Apicomplexan parasites that have 2 hosts in their life cycles. The definitive hosts excrete unsporulated (Neospora caninum, T gondii) or sporulated (Sarcocystis spp.) oocysts in their feces after ingesting tissue cysts from the tissues of ruminant intermediate hosts. These coccidians can cause abortion and neonatal mortality in ruminants. T gondii and Sarcocystis hominis (from cattle) are zoonotic. This article reviews information on the etiology, life cycle, diagnosis, control and prevention of these parasites and the diseases they cause in ruminants.
- Published
- 2020
13. Toxoplasmosis in wild and domestic animals
- Author
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Biomedical Sciences and Pathobiology, Lindsay, David S., Dubey, Jitender P., Biomedical Sciences and Pathobiology, Lindsay, David S., and Dubey, Jitender P.
- Published
- 2020
14. Confirmation of Sarcocystis jamaicensis Sarcocysts in IFN-γ Gene Knockout Mice Orally Inoculated With Sporocysts From a Red-Tailed Hawk (Buteo jamaicensis)
- Author
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Dubey, J. P., Cerqueira-Cezar, Camila K., Murata, Fernando H. A., Mowery, J. D., Scott, D., von Dohlen, A. Rosypal, Lindsay, David S., Dubey, J. P., Cerqueira-Cezar, Camila K., Murata, Fernando H. A., Mowery, J. D., Scott, D., von Dohlen, A. Rosypal, and Lindsay, David S.
- Abstract
Here, we report confirmation of sarcocysts of Sarcocystis jamaicensis in an experimental intermediate host, IFN-gamma gene knockout (KO) mice orally inoculated sporocysts from its natural definitive host, a red-tailed hawk (Buteo jamaicensis) (RTH). A RTH submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because it could not be rehabilitated and released. Fully sporulated sporocysts from intestinal scrapings of the RTH were orally fed to 2 laboratory-reared outbred Swiss Webster mice (SW; Mus musculus) and to 2 KO mice. The sporocysts were infective for KO mice but not to SW mice. Both SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in their tissues when euthanized on day 54 post-inoculation (PI). The KO mice developed neurological signs and were necropsied 38-54 days PI. Schizonts/merozoites were found in both KO mice euthanized and they were confined to the brain. The predominant lesion was meningoencephalitis. Microscopic sarcocysts were found in muscles of both KO mice. When viewed with light microscopy, the sarcocyst wall appeared thin (<1 mu m thick) and smooth. Ultrastructural details of sarcocysts are described.
- Published
- 2019
- Full Text
- View/download PDF
15. Can levamisole upregulate the equine cell-mediated macrophage (M1) dendritic cell (DC1) T-helper 1 (CD4 Th1) T-cytotoxic (CD8) immune response in vitro?
- Author
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Witonsky, Sharon G., Buechner-Maxwell, Virginia A., Santonastasto, Amy, Pleasant, R. Scott, Werre, Stephen R., Wagner, Bettina, Ellison, Siobhan, Lindsay, David S., Witonsky, Sharon G., Buechner-Maxwell, Virginia A., Santonastasto, Amy, Pleasant, R. Scott, Werre, Stephen R., Wagner, Bettina, Ellison, Siobhan, and Lindsay, David S.
- Abstract
Background: Equine protozoal myeloencephalitis (EPM) is a common and devastating neurologic disease of horses in the United States. Because some EPM-affected horses have decreased immune responses, immunomodulators such as levamisole have been proposed as supplemental treatments. However, little is known about levamisole's effects or its mechanism of action in horses. Objective: Levamisole in combination with another mitogen will stimulate a macrophage 1 (M1), dendritic cell 1 (DC1), T-helper 1 (CD4 Th1), and T-cytotoxic (CD8) immune response in equine peripheral blood mononuclear cells (PBMCs) in vitro as compared to mitogen alone. Animals: Ten neurologically normal adult horses serologically negative for Sarcocystis neurona. Methods: Prospective study. Optimal conditions for levamisole were determined based on cellular proliferation. Peripheral blood mononuclear cells were then cultured using optimal conditions of mitogen and levamisole to identify the immune phenotype, based on subset-specific activation markers, intracellular cytokine production, and cytokine concentrations in cell supernatants. Subset-specific proliferation was determined using a vital stain. Results: Concanavalin A (conA) with levamisole, but not levamisole alone, resulted in a significant decrease (P <.05) in PBMC proliferation compared to conA alone. Levamisole alone did not elicit a specific immune phenotype different than that induced by conA. Conclusion and Clinical Importance: Levamisole co-cultured with conA significantly attenuated the PBMC proliferative response as compared with conA. If the mechanisms by which levamisole modulates the immune phenotype can be further defined, levamisole may have potential use in the treatment of inflammatory diseases.
- Published
- 2019
- Full Text
- View/download PDF
16. Comparison of diagnostic techniques for detection of Giardia duodenalis in dogs and cats
- Author
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Saleh, Meriam N., Heptinstall, Jack R., Johnson, Eileen M., Ballweber, Lora R., Lindsay, David S., Werre, Stephen R., Herbein, Joel F., Zajac, Anne M., Saleh, Meriam N., Heptinstall, Jack R., Johnson, Eileen M., Ballweber, Lora R., Lindsay, David S., Werre, Stephen R., Herbein, Joel F., and Zajac, Anne M.
- Abstract
Background An evaluation of currently available in-clinic diagnostic tests for Giardia duodenalis infection of dogs and cats has not been performed. In addition, there is discordance among published diagnostic comparisons. The absence of a true gold standard for detecting Giardia duodenalis also complicates diagnostic evaluations. Objectives To evaluate diagnostic tests commercially available in the United States for detecting Giardia duodenalis in dogs and cats, in comparison to a widely used reference test, the direct immunofluorescent assay (IFA), and also to compare the results of 2 methods of analysis: comparison of diagnostic tests to a reference test (IFA) and Bayesian analysis. Animals Fecal samples from a convenience sample of 388 cats and dogs located in Colorado, Oklahoma, and Virginia. Methods Fecal samples were tested for Giardia duodenalis by zinc sulfate centrifugal fecal flotation and 4 different commercial diagnostic immunoassays. Results were analyzed via Bayesian analysis and by comparison to the IFA as the reference test. Results Sensitivity and specificity by comparison to IFA was >= 82% and >= 90%, respectively, for all diagnostic tests in dogs and cats. When analyzed via Bayesian analysis, sensitivity and specificity were >= 83% and >= 95%, respectively. When ZnSO4 centrifugal fecal flotation results were combined with immunoassay results, there was no longer a significant difference between the sensitivities of the commercial in-clinic immunoassays. Conclusion and Clinical Relevance The Bayesian analysis validates using IFA as the reference test. Differences in commercial in-clinic immunoassay sensitivities can be mitigated when the results are combined with ZnSO4 centrifugal fecal flotation results.
- Published
- 2019
- Full Text
- View/download PDF
17. Prevalence of Sarcocysts in the Muscles of Raptors From a Rehabilitation Center in North Carolina
- Author
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von Dohlen, Alexa Rosypal, Scott, David, Dubey, Jitender P., Lindsay, David S., von Dohlen, Alexa Rosypal, Scott, David, Dubey, Jitender P., and Lindsay, David S.
- Abstract
The life cycle of Sarcocystis species is heteroxenous (2-host), with carnivores being the definitive host and herbivores serving as intermediate hosts in predator-prey relationships. Raptors (eagles, hawks, falcons, and owls) are apex predators and are not consumed routinely by other carnivores, making the occurrence of sarcocysts in their muscles unusual. Recent reports of sarcocysts in eagles and owls with Sarcocystis encephalitis suggests that this condition may be becoming more frequent, and Sarcocystis falcatula has been implicated as the agent of encephalitis in golden (Aquila chrysaetos) and bald eagles (Haliaeetus leucocephalus) as well as great horned owls (Bubo virginianus). The present study was done to determine the prevalence of sarcocysts of Sarcocystis species in the muscles of raptors from the southeastern United States. Pectoral and heart muscle from 204 raptor patients from the Carolina Raptor Center, Huntersville, North Carolina were tested for the presence of Sarcocystis species using histology. Only a few sarcocysts were seen in sections of pectoral muscle from 39 of 204 raptors (19.1%) and heart muscle from 9 that also had sarcocysts in their pectoral muscle. Two structural types of sarcocysts, thin-walled (1 mu m; 62%) or thick-walled (>2 mu m, 38%), were seen. Statistical analysis of raptor age and gender was done by Fisher's exact test on samples from raptors with 20 or more samples per group. The prevalence of sarcocysts by age (2 yr or more) was significant for red-shouldered hawks (Buteo lineatus) (P = 0.022) and Cooper's hawks (Accipiter cooperii) (P = 0.028). Sarcocyst prevalence in male raptors from these groups evaluated statistically were always less than in females. Prevalence in female red-tailed hawks (Buteo jamaicensis) (42.1%) was significantly greater than in males (6.7%) using Fisher's exact test (P = 0.047). Examination of case histories from the 39 sarcocyst-positive raptors did not reveal an association with sarcocysts in r
- Published
- 2019
- Full Text
- View/download PDF
18. New Observations Allowing the Differentiation of Late Asexual Stages of Cystoisospora Canis From Developing Microgamonts in the Intestines of Experimentally Infected Dogs
- Author
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Dubey, Jitender P., Lindsay, David S., Dubey, Jitender P., and Lindsay, David S.
- Abstract
The coccidian parasite Cystoisospora canis (syn. Isospora canis) can cause clinical disease in dogs. Three generations of meronts are reported to occur in the small intestine of experimentally infected dogs before gametogony and oocyst formation. Oocyst excretion in the feces occurs at 9 to 11 days post-inoculation (PI). We examined the late asexual and sexual development of C. canis in 2 dogs necropsied 10 days after oral inoculation with 100,000 sporulated C. canis oocysts; both dogs had excreted oocysts 9 days PI. Asexual and sexual stages were seen in the lamina propria, throughout the small intestine in sections stained with hematoxylin and eosin from both dogs. In other studies of the C. canis life cycle, little attention has been given to distinguishing the last asexual generation of meronts and early microgamonts that can appear similar due to their stage of maturation and both having multiple nuclei. Here we report newly identified features of developing meronts and microgamonts and their distinction from each other by using sections processed using the periodic acid-Schiff (PAS) reaction. Using this method, we demonstrated that PAS-positive granules could be used to identify microgamonts and differentiate them from developing meront stages. These findings will aid pathologists and others in properly identifying coccidial parasites, in determining the cause of microscopic lesions in intestinal tissue, and in accurately identifying etiological agents.
- Published
- 2019
- Full Text
- View/download PDF
19. Re-Evaluation of Asynchronous Asexual Development of Cystoisospora canis in Intestines of Dogs
- Author
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Dubey, Jitender P., Lindsay, David S., Dubey, Jitender P., and Lindsay, David S.
- Abstract
The coccidian parasite Cystoisospora canis (syn. Isospora canis) can cause clinical disease in dogs. Three generation of schizonts have been reported in the small intestine of dogs before oocysts are excreted 9-11 days post inoculation (PI). Here, we re-evaluated asexual development of C. canis in 2 dogs necropsied 10 days after oral inoculation with 100,000 C. canis oocysts; both dogs had excreted oocysts 9 days PI. Asexual and sexual stages were seen in the lamina propria throughout the small intestine. Merozoites of different sizes were present, often in the same vacuole. They were arranged singly, in pairs, and many within a single parasitophorous vacuole. The maximum number of nuclei within developing merozoites in a group was 8, but it could not be discerned if they were individual nuclei or parts of merozoites. Findings of abundant asexual stages 1 day after dogs had started excreting oocysts indicated continued asexual multiplication beyond the prepatent period. The stages found resemble the 3 generations reported previously. The mode of division of the asexual generations remains unclear. The results of the present study indicate that there are many generations that are difficult to determine because of the multiplication of merozoites in the original host cell without leaving it to enter new host cells. From the literature, it is evident that cat and dog coccidia (Cystoisospora spp.) divide by more than 1 type of division, including endodyogeny. In the past, the schizont/meront groups containing more than 1 generation have been called "cysts." However, cyst is not an accurate term because it is best used for an orally infective stage of coccidia; monozoic tissue cysts of C. canis can occur in paratenic hosts in extraintestinal organs. We recommend the term "types" as originally proposed for intestinal stages of Toxoplasma gondii and used for the original description of the life cycle of C. suis of swine when describing endogenous stages of the Sarcocystida
- Published
- 2019
- Full Text
- View/download PDF
20. Comparison of diagnostic techniques for detection of Giardia duodenalis in dogs and cats
- Author
-
Saleh, Meriam N., Heptinstall, Jack R., Johnson, Eileen M., Ballweber, Lora R., Lindsay, David S., Werre, Stephen R., Herbein, Joel F., Zajac, Anne M., Saleh, Meriam N., Heptinstall, Jack R., Johnson, Eileen M., Ballweber, Lora R., Lindsay, David S., Werre, Stephen R., Herbein, Joel F., and Zajac, Anne M.
- Abstract
Background An evaluation of currently available in-clinic diagnostic tests for Giardia duodenalis infection of dogs and cats has not been performed. In addition, there is discordance among published diagnostic comparisons. The absence of a true gold standard for detecting Giardia duodenalis also complicates diagnostic evaluations. Objectives To evaluate diagnostic tests commercially available in the United States for detecting Giardia duodenalis in dogs and cats, in comparison to a widely used reference test, the direct immunofluorescent assay (IFA), and also to compare the results of 2 methods of analysis: comparison of diagnostic tests to a reference test (IFA) and Bayesian analysis. Animals Fecal samples from a convenience sample of 388 cats and dogs located in Colorado, Oklahoma, and Virginia. Methods Fecal samples were tested for Giardia duodenalis by zinc sulfate centrifugal fecal flotation and 4 different commercial diagnostic immunoassays. Results were analyzed via Bayesian analysis and by comparison to the IFA as the reference test. Results Sensitivity and specificity by comparison to IFA was >= 82% and >= 90%, respectively, for all diagnostic tests in dogs and cats. When analyzed via Bayesian analysis, sensitivity and specificity were >= 83% and >= 95%, respectively. When ZnSO4 centrifugal fecal flotation results were combined with immunoassay results, there was no longer a significant difference between the sensitivities of the commercial in-clinic immunoassays. Conclusion and Clinical Relevance The Bayesian analysis validates using IFA as the reference test. Differences in commercial in-clinic immunoassay sensitivities can be mitigated when the results are combined with ZnSO4 centrifugal fecal flotation results.
- Published
- 2019
21. Cystoisospora Species Insights From Development in vitro
- Author
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Lindsay, David S. and Lindsay, David S.
- Published
- 2019
22. Re-Evaluation of Asynchronous Asexual Development of Cystoisospora canis in Intestines of Dogs
- Author
-
Dubey, Jitender P., Lindsay, David S., Dubey, Jitender P., and Lindsay, David S.
- Abstract
The coccidian parasite Cystoisospora canis (syn. Isospora canis) can cause clinical disease in dogs. Three generation of schizonts have been reported in the small intestine of dogs before oocysts are excreted 9-11 days post inoculation (PI). Here, we re-evaluated asexual development of C. canis in 2 dogs necropsied 10 days after oral inoculation with 100,000 C. canis oocysts; both dogs had excreted oocysts 9 days PI. Asexual and sexual stages were seen in the lamina propria throughout the small intestine. Merozoites of different sizes were present, often in the same vacuole. They were arranged singly, in pairs, and many within a single parasitophorous vacuole. The maximum number of nuclei within developing merozoites in a group was 8, but it could not be discerned if they were individual nuclei or parts of merozoites. Findings of abundant asexual stages 1 day after dogs had started excreting oocysts indicated continued asexual multiplication beyond the prepatent period. The stages found resemble the 3 generations reported previously. The mode of division of the asexual generations remains unclear. The results of the present study indicate that there are many generations that are difficult to determine because of the multiplication of merozoites in the original host cell without leaving it to enter new host cells. From the literature, it is evident that cat and dog coccidia (Cystoisospora spp.) divide by more than 1 type of division, including endodyogeny. In the past, the schizont/meront groups containing more than 1 generation have been called "cysts." However, cyst is not an accurate term because it is best used for an orally infective stage of coccidia; monozoic tissue cysts of C. canis can occur in paratenic hosts in extraintestinal organs. We recommend the term "types" as originally proposed for intestinal stages of Toxoplasma gondii and used for the original description of the life cycle of C. suis of swine when describing endogenous stages of the Sarcocystida
- Published
- 2019
23. New Observations Allowing the Differentiation of Late Asexual Stages of Cystoisospora Canis From Developing Microgamonts in the Intestines of Experimentally Infected Dogs
- Author
-
Dubey, Jitender P., Lindsay, David S., Dubey, Jitender P., and Lindsay, David S.
- Abstract
The coccidian parasite Cystoisospora canis (syn. Isospora canis) can cause clinical disease in dogs. Three generations of meronts are reported to occur in the small intestine of experimentally infected dogs before gametogony and oocyst formation. Oocyst excretion in the feces occurs at 9 to 11 days post-inoculation (PI). We examined the late asexual and sexual development of C. canis in 2 dogs necropsied 10 days after oral inoculation with 100,000 sporulated C. canis oocysts; both dogs had excreted oocysts 9 days PI. Asexual and sexual stages were seen in the lamina propria, throughout the small intestine in sections stained with hematoxylin and eosin from both dogs. In other studies of the C. canis life cycle, little attention has been given to distinguishing the last asexual generation of meronts and early microgamonts that can appear similar due to their stage of maturation and both having multiple nuclei. Here we report newly identified features of developing meronts and microgamonts and their distinction from each other by using sections processed using the periodic acid-Schiff (PAS) reaction. Using this method, we demonstrated that PAS-positive granules could be used to identify microgamonts and differentiate them from developing meront stages. These findings will aid pathologists and others in properly identifying coccidial parasites, in determining the cause of microscopic lesions in intestinal tissue, and in accurately identifying etiological agents.
- Published
- 2019
24. Prevalence of Sarcocysts in the Muscles of Raptors From a Rehabilitation Center in North Carolina
- Author
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von Dohlen, Alexa Rosypal, Scott, David, Dubey, Jitender P., Lindsay, David S., von Dohlen, Alexa Rosypal, Scott, David, Dubey, Jitender P., and Lindsay, David S.
- Abstract
The life cycle of Sarcocystis species is heteroxenous (2-host), with carnivores being the definitive host and herbivores serving as intermediate hosts in predator-prey relationships. Raptors (eagles, hawks, falcons, and owls) are apex predators and are not consumed routinely by other carnivores, making the occurrence of sarcocysts in their muscles unusual. Recent reports of sarcocysts in eagles and owls with Sarcocystis encephalitis suggests that this condition may be becoming more frequent, and Sarcocystis falcatula has been implicated as the agent of encephalitis in golden (Aquila chrysaetos) and bald eagles (Haliaeetus leucocephalus) as well as great horned owls (Bubo virginianus). The present study was done to determine the prevalence of sarcocysts of Sarcocystis species in the muscles of raptors from the southeastern United States. Pectoral and heart muscle from 204 raptor patients from the Carolina Raptor Center, Huntersville, North Carolina were tested for the presence of Sarcocystis species using histology. Only a few sarcocysts were seen in sections of pectoral muscle from 39 of 204 raptors (19.1%) and heart muscle from 9 that also had sarcocysts in their pectoral muscle. Two structural types of sarcocysts, thin-walled (1 mu m; 62%) or thick-walled (>2 mu m, 38%), were seen. Statistical analysis of raptor age and gender was done by Fisher's exact test on samples from raptors with 20 or more samples per group. The prevalence of sarcocysts by age (2 yr or more) was significant for red-shouldered hawks (Buteo lineatus) (P = 0.022) and Cooper's hawks (Accipiter cooperii) (P = 0.028). Sarcocyst prevalence in male raptors from these groups evaluated statistically were always less than in females. Prevalence in female red-tailed hawks (Buteo jamaicensis) (42.1%) was significantly greater than in males (6.7%) using Fisher's exact test (P = 0.047). Examination of case histories from the 39 sarcocyst-positive raptors did not reveal an association with sarcocysts in r
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- 2019
25. Can levamisole upregulate the equine cell-mediated macrophage (M1) dendritic cell (DC1) T-helper 1 (CD4 Th1) T-cytotoxic (CD8) immune response in vitro?
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Witonsky, Sharon G., Buechner-Maxwell, Virginia A., Santonastasto, Amy, Pleasant, R. Scott, Werre, Stephen R., Wagner, Bettina, Ellison, Siobhan, Lindsay, David S., Witonsky, Sharon G., Buechner-Maxwell, Virginia A., Santonastasto, Amy, Pleasant, R. Scott, Werre, Stephen R., Wagner, Bettina, Ellison, Siobhan, and Lindsay, David S.
- Abstract
Background: Equine protozoal myeloencephalitis (EPM) is a common and devastating neurologic disease of horses in the United States. Because some EPM-affected horses have decreased immune responses, immunomodulators such as levamisole have been proposed as supplemental treatments. However, little is known about levamisole's effects or its mechanism of action in horses. Objective: Levamisole in combination with another mitogen will stimulate a macrophage 1 (M1), dendritic cell 1 (DC1), T-helper 1 (CD4 Th1), and T-cytotoxic (CD8) immune response in equine peripheral blood mononuclear cells (PBMCs) in vitro as compared to mitogen alone. Animals: Ten neurologically normal adult horses serologically negative for Sarcocystis neurona. Methods: Prospective study. Optimal conditions for levamisole were determined based on cellular proliferation. Peripheral blood mononuclear cells were then cultured using optimal conditions of mitogen and levamisole to identify the immune phenotype, based on subset-specific activation markers, intracellular cytokine production, and cytokine concentrations in cell supernatants. Subset-specific proliferation was determined using a vital stain. Results: Concanavalin A (conA) with levamisole, but not levamisole alone, resulted in a significant decrease (P <.05) in PBMC proliferation compared to conA alone. Levamisole alone did not elicit a specific immune phenotype different than that induced by conA. Conclusion and Clinical Importance: Levamisole co-cultured with conA significantly attenuated the PBMC proliferative response as compared with conA. If the mechanisms by which levamisole modulates the immune phenotype can be further defined, levamisole may have potential use in the treatment of inflammatory diseases.
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- 2019
26. Public rights: copyright s public domains
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Greenleaf, Graham, Lindsay, David, Greenleaf, Graham, and Lindsay, David
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- 2018
27. Public rights: copyright s public domains
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Greenleaf, Graham, Lindsay, David, Greenleaf, Graham, and Lindsay, David
- Published
- 2018
28. Public rights: copyright s public domains
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Greenleaf, Graham, Lindsay, David, Greenleaf, Graham, and Lindsay, David
- Published
- 2018
29. Prevalence of zoonotic parasites in feral cats of Central Virginia, USA
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Taetzsch, Sara J., Gruszynski, Karen R., Bertke, Andrea S., Dubey, Jitender P., Monti, Katelynn A., Zajac, Anne M., Lindsay, David S., Taetzsch, Sara J., Gruszynski, Karen R., Bertke, Andrea S., Dubey, Jitender P., Monti, Katelynn A., Zajac, Anne M., and Lindsay, David S.
- Abstract
Felis catus, the domestic cat, is the definitive host for parasites that may result in adverse health outcomes in humans. Prevalence data of zoonotic parasites in feral cats, which are free-roaming domestic cats that are born and live in the wild, are limited. The objective of this study was to assess seroprevalence of Toxoplasma gondii antibodies and copro-prevalence of potentially zoonotic parasites in feral cats and to evaluate risk factors for seropositivity and faecal excretion of parasites. In this cross-sectional survey, 275 feral cats at Trap-Neuter-Release clinics in Central Virginia were tested for parasites via faecal flotation, direct immunofluorescence assay (faeces) and modified agglutination testing (serum). Toxoplasma gondii seroprevalence was 22.35% (95% CI: 17.47-27.86). Faecal prevalence of T.gondii-like oocysts was 1.04% (95% CI: 0.13-3.71), Toxocara cati 58.85% (95% CI: 51.54-65.89), Ancylostoma spp. 18.75% (95% CI: 13.49-25.00), Giardia duodenalis 5.73% (95% CI: 2.89-10.02) and Cryptosporidium spp. 3.33% (95% CI: 1.37-7.24). Female cats were more likely than males to excrete faecal Ancylostoma spp. eggs (OR 2.88; 95% CI 1.34-6.17). Adults were more likely than immature cats to be seropositive (OR 2.10; 95% CI: 1.11-3.97) and to excrete faecal Ancylostoma spp. eggs (OR 2.57; 95% CI: 1.10-5.99). However, immature cats were more likely than adults to excrete T.cati eggs (OR 6.79; 95% CI: 3.31-13.90) and to excrete one or more potentially zoonotic species (OR 4.67; 95% CI: 2.28-9.55) in faeces. Results of this study have implications for human and animal health and highlight the importance of collaboration between public health, medical and veterinary communities in preventive efforts.
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- 2018
- Full Text
- View/download PDF
30. Public rights: copyright s public domains
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Greenleaf, Graham, Lindsay, David, Greenleaf, Graham, and Lindsay, David
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- 2018
31. Perils of speed dating: an Australian success story in Chinese outbound tourism
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Lindsay, David, Kriz, Anton, Johns, Raechel, Keating, Byron, Lindsay, David, Kriz, Anton, Johns, Raechel, and Keating, Byron
- Abstract
This paper provides insights and lessons about how Western tourism operators can build and maintain business-to-business relationships with Chinese tourism providers. The case analyses how Tangalooma Island Resort Pty Ltd approached the challenge of developing business networks and how they have sustained this activity for over a decade to become a major destination for Chinese visitors to Australia. While there is no shortage of research on the Chinese notion of guanxi, this study uses a novel multi-dimensional cultural intelligence perspective to synthesise Chinese and Australian views on the drivers of long-term commercial success. The frameworks and insights provided make a valuable and timely contribution to our understanding of how Western firms can approach China tourism opportunities, and importantly, provide lessons on the nuances of effective relationship development between Western and Chinese individuals and firms. This critical single case study highlights the importance of business negotiation and need for deepening cultural logic with appropriate pacing by key protagonists in the Western firm. Nurturing and growing interpersonal cultural skills is fundamental and helps build inter-firm bonds, resource ties and activity links. This is discussed using the actors–activities–resources model promoted within the context of industrial marketing and purchasing. Future research could extend the findings through additional case studies, or further empirical validation.
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- 2018
32. Public rights: copyright s public domains
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Greenleaf, Graham, Lindsay, David, Greenleaf, Graham, and Lindsay, David
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- 2018
33. Prevalence of zoonotic parasites in feral cats of Central Virginia, USA
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Taetzsch, Sara J., Gruszynski, Karen R., Bertke, Andrea S., Dubey, Jitender P., Monti, Katelynn A., Zajac, Anne M., Lindsay, David S., Taetzsch, Sara J., Gruszynski, Karen R., Bertke, Andrea S., Dubey, Jitender P., Monti, Katelynn A., Zajac, Anne M., and Lindsay, David S.
- Abstract
Felis catus, the domestic cat, is the definitive host for parasites that may result in adverse health outcomes in humans. Prevalence data of zoonotic parasites in feral cats, which are free-roaming domestic cats that are born and live in the wild, are limited. The objective of this study was to assess seroprevalence of Toxoplasma gondii antibodies and copro-prevalence of potentially zoonotic parasites in feral cats and to evaluate risk factors for seropositivity and faecal excretion of parasites. In this cross-sectional survey, 275 feral cats at Trap-Neuter-Release clinics in Central Virginia were tested for parasites via faecal flotation, direct immunofluorescence assay (faeces) and modified agglutination testing (serum). Toxoplasma gondii seroprevalence was 22.35% (95% CI: 17.47-27.86). Faecal prevalence of T.gondii-like oocysts was 1.04% (95% CI: 0.13-3.71), Toxocara cati 58.85% (95% CI: 51.54-65.89), Ancylostoma spp. 18.75% (95% CI: 13.49-25.00), Giardia duodenalis 5.73% (95% CI: 2.89-10.02) and Cryptosporidium spp. 3.33% (95% CI: 1.37-7.24). Female cats were more likely than males to excrete faecal Ancylostoma spp. eggs (OR 2.88; 95% CI 1.34-6.17). Adults were more likely than immature cats to be seropositive (OR 2.10; 95% CI: 1.11-3.97) and to excrete faecal Ancylostoma spp. eggs (OR 2.57; 95% CI: 1.10-5.99). However, immature cats were more likely than adults to excrete T.cati eggs (OR 6.79; 95% CI: 3.31-13.90) and to excrete one or more potentially zoonotic species (OR 4.67; 95% CI: 2.28-9.55) in faeces. Results of this study have implications for human and animal health and highlight the importance of collaboration between public health, medical and veterinary communities in preventive efforts.
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- 2018
34. Prevalence of zoonotic parasites in feral cats of Central Virginia, USA
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Taetzsch, Sara J., Gruszynski, Karen R., Bertke, Andrea S., Dubey, Jitender P., Monti, Katelynn A., Zajac, Anne M., Lindsay, David S., Taetzsch, Sara J., Gruszynski, Karen R., Bertke, Andrea S., Dubey, Jitender P., Monti, Katelynn A., Zajac, Anne M., and Lindsay, David S.
- Abstract
Felis catus, the domestic cat, is the definitive host for parasites that may result in adverse health outcomes in humans. Prevalence data of zoonotic parasites in feral cats, which are free-roaming domestic cats that are born and live in the wild, are limited. The objective of this study was to assess seroprevalence of Toxoplasma gondii antibodies and copro-prevalence of potentially zoonotic parasites in feral cats and to evaluate risk factors for seropositivity and faecal excretion of parasites. In this cross-sectional survey, 275 feral cats at Trap-Neuter-Release clinics in Central Virginia were tested for parasites via faecal flotation, direct immunofluorescence assay (faeces) and modified agglutination testing (serum). Toxoplasma gondii seroprevalence was 22.35% (95% CI: 17.47-27.86). Faecal prevalence of T.gondii-like oocysts was 1.04% (95% CI: 0.13-3.71), Toxocara cati 58.85% (95% CI: 51.54-65.89), Ancylostoma spp. 18.75% (95% CI: 13.49-25.00), Giardia duodenalis 5.73% (95% CI: 2.89-10.02) and Cryptosporidium spp. 3.33% (95% CI: 1.37-7.24). Female cats were more likely than males to excrete faecal Ancylostoma spp. eggs (OR 2.88; 95% CI 1.34-6.17). Adults were more likely than immature cats to be seropositive (OR 2.10; 95% CI: 1.11-3.97) and to excrete faecal Ancylostoma spp. eggs (OR 2.57; 95% CI: 1.10-5.99). However, immature cats were more likely than adults to excrete T.cati eggs (OR 6.79; 95% CI: 3.31-13.90) and to excrete one or more potentially zoonotic species (OR 4.67; 95% CI: 2.28-9.55) in faeces. Results of this study have implications for human and animal health and highlight the importance of collaboration between public health, medical and veterinary communities in preventive efforts.
- Published
- 2018
35. Language Learner Identity of Mormon Missionaries: Implications for Second Language Pedagogy and Research
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Dupuy, Beatrice, Waugh, Linda, Kayi-Aydar, Hayriye, Lindsay, David, Vasquez-Wright, Christopher Bennett, Dupuy, Beatrice, Waugh, Linda, Kayi-Aydar, Hayriye, Lindsay, David, and Vasquez-Wright, Christopher Bennett
- Abstract
This dissertation is comprised of three studies that layer social and cognitive perspectives of the Mormon missionary language learner identity. This research explores factors that enhance and constrain their second language (L2) learning and defends arts-based research as a way to inquire the role emotions have in learning an L2. Possible implications for other language learning contexts are discussed. The first article is an exploratory study that examines the language learning experiences of Mormon missionaries by inquiring their unique language learning ideology called “the gift of tongues”, to miraculously speak the second language beyond one's ability through divine assistance. The study uses the anthropological framework of the figured world (see Holland et al., 1998) to understand how participants self-author their belief within their cultural frame through a Bakhtinian perspective of voice (see Bakhtin, 1981). The study identifies what inspired the participants to become missionaries, what the gift of tongues means to the participants, how this belief is constructed and performed by narrative in their cultural frame, and explains how their experience with the gift may be understood from a cognitive perspective. Participants were 17 Spanish language learning missionaries from various U.S. regions assigned to Southern Arizona for 18-24 months. Data were collected through elicitation of their narratives with writing prompts and semi-structured focus-group interviews that evoked their language learning experience from their figured world. Findings indicate that all participants first wanted to be proselytizing missionaries before receiving the assignment to learn an L2. By gender, they are recruited into their figured world differently. Their experience with the gift seems to foster a powerful form of self-compassionate autonomous language learning which may not be replicated beyond their cultural frame. Their personal narratives contain appropriations of insti
- Published
- 2018
36. Public rights: copyright s public domains
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Greenleaf, Graham, Lindsay, David, Greenleaf, Graham, and Lindsay, David
- Published
- 2018
37. Sarcocystis Strixi N. Sp From a Barred Owl (Strix varia) Definitive Host and Interferon Gamma Gene Knockout Mice as Experimental Intermediate Host
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Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Cerqueira-Cezar, Camila K., Rosenthal, B. M., Dubey, Jitender P., Lindsay, David S., Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Cerqueira-Cezar, Camila K., Rosenthal, B. M., Dubey, Jitender P., and Lindsay, David S.
- Abstract
Here we report a new species of Sarcocystis with a barred owl (Strix varia) as the natural definitive host and interferon gamma gene knockout (KO) mice as an experimental intermediate host. A barred owl submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because of paralysis. Fully sporulated 12.539.9 lm sporocysts were found in intestinal scrapings from the owl. Sporocysts from the barred owl were orally fed to 4 laboratory-reared outbred Swiss Webster (SW) (Mus musculus) and 8 KO mice. All mice remained asymptomatic. Microscopic sarcocysts were found in all 5 KO mice euthanized on day 32, 59, 120, 154, and 206 post- inoculation (PI), not in KO mice euthanized on day 4, 8, and 14 PI. Sarcocysts were not found in any SW mice euthanized on day 72, 120, 206, and 210 PI. Sarcocysts were microscopic, up to 70 lm wide. By light microscopy, the sarcocyst wall, 2 lm thick had undulating, flat to conical, protrusions of varying dimensions. Numerous sarcocysts were seen in the histological sections of tongue and skeletal muscles from the abdomen, limbs, and eye but not in the heart. By transmission electron microscopy, the sarcocyst wall was "type 1j.'' The ground substance layer (gs) was homogenous, up to 2 lm thick, with very fine granules, and a few vesicles concentrated toward the villar projections. No microtubules were seen in the gs. Longitudinally cut bradyzoites at 206 days PI were 7.8 3 2.2 lm. Based on molecular characterization using 18S rRNA, 28S rRNA, and cox1 genes and morphology of sarcocysts, the parasite in the present study was biologically and structurally different from species so far described, and we therefore propose a new species name, Sarcocystis strixi n. sp.
- Published
- 2017
- Full Text
- View/download PDF
38. Sarcocystis Jamaicensis N. Sp., From Red-Tailed Hawks (Buteo Jamaicensis) Definitive Host and Ifn-Gamma Gene Knockout Mice as Experimental Intermediate Host
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Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Rosenthal, B. M., Dubey, Jitender P., Lindsay, David S., Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Rosenthal, B. M., Dubey, Jitender P., and Lindsay, David S.
- Abstract
Here, we report a new species of Sarcocystis with red-tailed hawk (RTH, Buteo jamaicensis) as the natural definitive host and IFN-gamma gene knockout (KO) mice as an experimental intermediate host in which sarcocysts form in muscle. Two RTHs submitted to the Carolina Raptor Center, Huntersville, North Carolina, were euthanized because they could not be rehabilitated and released. Fully sporulated 12.5 x 9.9-mu m sized sporocysts were found in intestinal scrapings of both hawks. Sporocysts were orally fed to laboratory-reared outbred Swiss Webster mice (SW, Mus musculus) and also to KO mice. The sporocysts were infective for KO mice but not for SW mice. All SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in any SW mice euthanized on days 54, 77, 103 (n = 2) or 137 post-inoculation (PI). The KO mice developed neurological signs and were necropsied between 52 to 68 days PI. Schizonts/merozoites were found in all KO mice euthanized on days 52, 55 (n = 3), 59, 61 (n = 2), 66, and 68 PI and they were confined to the brain. The predominant lesion was meningoencephalitis characterized by perivascular cuffs, granulomas, and necrosis of the neural tissue. The schizonts/merozoites were located in neural tissue and were apparently extravascular. Brain homogenates from infected KO mice were infective to KO mice by subcutaneous inoculation and when seeded on to CV-1 cells. Microscopic sarcocysts were found in skeletal muscles of 5 of 8 KO mice euthanized between 55-61 days PI. Only a few sarcocysts were detected. Sarcocysts were microscopic, up to 3.5 mm long. When viewed with light microscopy, the sarcocyst wall appeared thin (< 1 mu m thick) and smooth. By transmission electron microscopy, the sarcocyst wall classified as "type 1j'' (new designation). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes revealed a close relationship with Sarcocystis microti and Sarcocystis glareoli; both species infect birds as definitive hos
- Published
- 2017
- Full Text
- View/download PDF
39. Isolation, molecular characterization, and in vitro schizogonic development of Sarcocystis sp ex Accipiter cooperii from a naturally infected Cooper's hawk (Accipiter cooperii)
- Author
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Lindsay, David S., Verma, Shiv K., Scott, David, Dubey, Jitender P., von Dohlen, Alexa Rosypal, Lindsay, David S., Verma, Shiv K., Scott, David, Dubey, Jitender P., and von Dohlen, Alexa Rosypal
- Abstract
Raptors serve as the definitive host for several Sarcocystis species. The complete life cycles of only a few of these Sarcocystis species that use birds of prey as definitive hosts have been described. In the present study, Sarcocystis species sporocysts were obtained from the intestine of a Cooper's hawk (Accipiter cooperii) and were used to infect cell cultures of African green monkey kidney cells to isolate a continuous culture and describe asexual stages of the parasite. Two clones of the parasite were obtained by limiting dilution. Asexual stages were used to obtain DNA for molecular classification and identification. PCR amplification and sequencing were done at three nuclear ribosomal DNA loci; 18S rRNA, 28S rRNA, and ITS-1, and the mitochondrial cytochrome c oxidase subunit 1 (cox1) locus. Examination of clonal isolates of the parasite indicated a single species related to S. columbae (termed Sarcocystis sp. ex Accipiter cooperii) was present in the Cooper's hawk. Our results document for the first time Sarcocystis sp. ex A. cooperii occurs naturally in an unknown intermediate host in North America and that Cooper's hawks (A. cooperii) are a natural definitive host. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
- Published
- 2017
- Full Text
- View/download PDF
40. Sarcocystis Pantherophisi N. Sp., From Eastern Rat Snakes (Pantherophis Alleghaniensis) as Definitive Hosts and Interferon Gamma Gene Knockout Mice as Experimental Intermediate Hosts
- Author
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Verma, S. K., Lindsay, David S., Mowery, J. D., Rosenthal, B. M., Dubey, Jitender P., Verma, S. K., Lindsay, David S., Mowery, J. D., Rosenthal, B. M., and Dubey, Jitender P.
- Abstract
Here, we report a new species, Sarcocystis pantherophisi n. sp., with the Eastern rat snake (Pantherophis alleghaniensis) as natural definitive host and the interferon gamma gene knockout (KO) mouse as the experimental intermediate host. Sporocysts (n = 15) from intestinal contents of the snake were 10.838.9 lm. Sporocysts were orally infective to KO mice but not to laboratory-raised albino outbred house mice (Mus musculus). The interferon gamma KO mice developed schizont-associated neurological signs, and schizonts were cultivated in vitro from the brain. Mature sarcocysts were found in skeletal muscles of KO mice examined 41 days postinoculation (PI). Sarcocysts were slender, up to 70 lm wide and up to 3.5 mm long. By light microscopy, sarcocysts appeared thin-walled (, 1 lm) without projections. By transmission electron microscopy, the sarcocyst wall was a variant of "type 1'' (type 1i, new designation). The parasitophorous vacuolar membrane (pvm) had approximately 100-nm-wide3100-nm-long bleb-like evaginations interspersed with 100-nm-wide 3 650-nm-long elongated protrusions at irregular distances, and invaginations into the ground substance layer (gs) for a very short distance (6 nm). The gs was smooth, up to 500 nm thick, without tubules, and contained a few vesicles. Longitudinally cut bradyzoites at 54 days PI were bananashaped, 7.832.2 lm (n = 5). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes indicated a close relationship with other Sarcocystis parasites that have snake-rodent life cycles. The parasite in the present study was molecularly and biologically similar to a previously reported isolate (designated earlier as Sarcocystis sp. ex Pantherophis alleghaniensis) from P. alleghaniensis, and it was structurally different from other Sarcocystis species so far described.
- Published
- 2017
- Full Text
- View/download PDF
41. Sarcocystis Jamaicensis N. Sp., From Red-Tailed Hawks (Buteo Jamaicensis) Definitive Host and Ifn-Gamma Gene Knockout Mice as Experimental Intermediate Host
- Author
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Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Rosenthal, B. M., Dubey, Jitender P., Lindsay, David S., Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Rosenthal, B. M., Dubey, Jitender P., and Lindsay, David S.
- Abstract
Here, we report a new species of Sarcocystis with red-tailed hawk (RTH, Buteo jamaicensis) as the natural definitive host and IFN-gamma gene knockout (KO) mice as an experimental intermediate host in which sarcocysts form in muscle. Two RTHs submitted to the Carolina Raptor Center, Huntersville, North Carolina, were euthanized because they could not be rehabilitated and released. Fully sporulated 12.5 x 9.9-mu m sized sporocysts were found in intestinal scrapings of both hawks. Sporocysts were orally fed to laboratory-reared outbred Swiss Webster mice (SW, Mus musculus) and also to KO mice. The sporocysts were infective for KO mice but not for SW mice. All SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in any SW mice euthanized on days 54, 77, 103 (n = 2) or 137 post-inoculation (PI). The KO mice developed neurological signs and were necropsied between 52 to 68 days PI. Schizonts/merozoites were found in all KO mice euthanized on days 52, 55 (n = 3), 59, 61 (n = 2), 66, and 68 PI and they were confined to the brain. The predominant lesion was meningoencephalitis characterized by perivascular cuffs, granulomas, and necrosis of the neural tissue. The schizonts/merozoites were located in neural tissue and were apparently extravascular. Brain homogenates from infected KO mice were infective to KO mice by subcutaneous inoculation and when seeded on to CV-1 cells. Microscopic sarcocysts were found in skeletal muscles of 5 of 8 KO mice euthanized between 55-61 days PI. Only a few sarcocysts were detected. Sarcocysts were microscopic, up to 3.5 mm long. When viewed with light microscopy, the sarcocyst wall appeared thin (< 1 mu m thick) and smooth. By transmission electron microscopy, the sarcocyst wall classified as "type 1j'' (new designation). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes revealed a close relationship with Sarcocystis microti and Sarcocystis glareoli; both species infect birds as definitive hos
- Published
- 2017
42. Sarcocystis Pantherophisi N. Sp., From Eastern Rat Snakes (Pantherophis Alleghaniensis) as Definitive Hosts and Interferon Gamma Gene Knockout Mice as Experimental Intermediate Hosts
- Author
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Verma, S. K., Lindsay, David S., Mowery, J. D., Rosenthal, B. M., Dubey, Jitender P., Verma, S. K., Lindsay, David S., Mowery, J. D., Rosenthal, B. M., and Dubey, Jitender P.
- Abstract
Here, we report a new species, Sarcocystis pantherophisi n. sp., with the Eastern rat snake (Pantherophis alleghaniensis) as natural definitive host and the interferon gamma gene knockout (KO) mouse as the experimental intermediate host. Sporocysts (n = 15) from intestinal contents of the snake were 10.838.9 lm. Sporocysts were orally infective to KO mice but not to laboratory-raised albino outbred house mice (Mus musculus). The interferon gamma KO mice developed schizont-associated neurological signs, and schizonts were cultivated in vitro from the brain. Mature sarcocysts were found in skeletal muscles of KO mice examined 41 days postinoculation (PI). Sarcocysts were slender, up to 70 lm wide and up to 3.5 mm long. By light microscopy, sarcocysts appeared thin-walled (, 1 lm) without projections. By transmission electron microscopy, the sarcocyst wall was a variant of "type 1'' (type 1i, new designation). The parasitophorous vacuolar membrane (pvm) had approximately 100-nm-wide3100-nm-long bleb-like evaginations interspersed with 100-nm-wide 3 650-nm-long elongated protrusions at irregular distances, and invaginations into the ground substance layer (gs) for a very short distance (6 nm). The gs was smooth, up to 500 nm thick, without tubules, and contained a few vesicles. Longitudinally cut bradyzoites at 54 days PI were bananashaped, 7.832.2 lm (n = 5). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes indicated a close relationship with other Sarcocystis parasites that have snake-rodent life cycles. The parasite in the present study was molecularly and biologically similar to a previously reported isolate (designated earlier as Sarcocystis sp. ex Pantherophis alleghaniensis) from P. alleghaniensis, and it was structurally different from other Sarcocystis species so far described.
- Published
- 2017
43. Isolation, molecular characterization, and in vitro schizogonic development of Sarcocystis sp ex Accipiter cooperii from a naturally infected Cooper's hawk (Accipiter cooperii)
- Author
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Lindsay, David S., Verma, Shiv K., Scott, David, Dubey, Jitender P., von Dohlen, Alexa Rosypal, Lindsay, David S., Verma, Shiv K., Scott, David, Dubey, Jitender P., and von Dohlen, Alexa Rosypal
- Abstract
Raptors serve as the definitive host for several Sarcocystis species. The complete life cycles of only a few of these Sarcocystis species that use birds of prey as definitive hosts have been described. In the present study, Sarcocystis species sporocysts were obtained from the intestine of a Cooper's hawk (Accipiter cooperii) and were used to infect cell cultures of African green monkey kidney cells to isolate a continuous culture and describe asexual stages of the parasite. Two clones of the parasite were obtained by limiting dilution. Asexual stages were used to obtain DNA for molecular classification and identification. PCR amplification and sequencing were done at three nuclear ribosomal DNA loci; 18S rRNA, 28S rRNA, and ITS-1, and the mitochondrial cytochrome c oxidase subunit 1 (cox1) locus. Examination of clonal isolates of the parasite indicated a single species related to S. columbae (termed Sarcocystis sp. ex Accipiter cooperii) was present in the Cooper's hawk. Our results document for the first time Sarcocystis sp. ex A. cooperii occurs naturally in an unknown intermediate host in North America and that Cooper's hawks (A. cooperii) are a natural definitive host. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
- Published
- 2017
44. Sarcocystis Strixi N. Sp From a Barred Owl (Strix varia) Definitive Host and Interferon Gamma Gene Knockout Mice as Experimental Intermediate Host
- Author
-
Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Cerqueira-Cezar, Camila K., Rosenthal, B. M., Dubey, Jitender P., Lindsay, David S., Verma, S. K., von Dohlen, Alexa Rosypal, Mowery, J. D., Scott, D., Cerqueira-Cezar, Camila K., Rosenthal, B. M., Dubey, Jitender P., and Lindsay, David S.
- Abstract
Here we report a new species of Sarcocystis with a barred owl (Strix varia) as the natural definitive host and interferon gamma gene knockout (KO) mice as an experimental intermediate host. A barred owl submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because of paralysis. Fully sporulated 12.539.9 lm sporocysts were found in intestinal scrapings from the owl. Sporocysts from the barred owl were orally fed to 4 laboratory-reared outbred Swiss Webster (SW) (Mus musculus) and 8 KO mice. All mice remained asymptomatic. Microscopic sarcocysts were found in all 5 KO mice euthanized on day 32, 59, 120, 154, and 206 post- inoculation (PI), not in KO mice euthanized on day 4, 8, and 14 PI. Sarcocysts were not found in any SW mice euthanized on day 72, 120, 206, and 210 PI. Sarcocysts were microscopic, up to 70 lm wide. By light microscopy, the sarcocyst wall, 2 lm thick had undulating, flat to conical, protrusions of varying dimensions. Numerous sarcocysts were seen in the histological sections of tongue and skeletal muscles from the abdomen, limbs, and eye but not in the heart. By transmission electron microscopy, the sarcocyst wall was "type 1j.'' The ground substance layer (gs) was homogenous, up to 2 lm thick, with very fine granules, and a few vesicles concentrated toward the villar projections. No microtubules were seen in the gs. Longitudinally cut bradyzoites at 206 days PI were 7.8 3 2.2 lm. Based on molecular characterization using 18S rRNA, 28S rRNA, and cox1 genes and morphology of sarcocysts, the parasite in the present study was biologically and structurally different from species so far described, and we therefore propose a new species name, Sarcocystis strixi n. sp.
- Published
- 2017
45. Guide de rédaction scientifique : L'hypothèse, clé de voûte de l'article scientifique
- Author
-
Lindsay, David, Poindron, Pascal, Lindsay, David, Lindsay, David, Poindron, Pascal, and Lindsay, David
- Abstract
Diffuser ses résultats de recherche est tout aussi important que le travail expérimental lui-même. Mais cette évidence se transforme bien souvent en une épreuve douloureuse lorsque vient le moment de la rédaction. Le chercheur débutant ou l'étudiant confronté à la rédaction de sa thèse ou de son premier article est alors assailli par une foule de questions : faut-il d’abord écrire le résumé ? Suivre l’ordre des différentes sections en commençant par l’introduction ? Cet ouvrage à l’usage des scientifiques en sciences biologiques, médicales, agronomiques et vétérinaires a été écrit pour décrypter les inconnues et pour répondre à toutes les questions qui assaillent les auteurs tout au long du processus de rédaction d’un article. L’ouvrage propose une manière d’aborder la rédaction en se concentrant sur la structure des articles plutôt que sur la grammaire et la syntaxe, en soulignant le rôle de l’hypothèse dans la construction de l’article. Il insiste également sur le fait que le style scientifique est avant tout celui de la logique.
- Published
- 2011
46. Guide de rédaction scientifique : L'hypothèse, clé de voûte de l'article scientifique
- Author
-
Lindsay, David, Poindron, Pascal, Lindsay, David, Lindsay, David, Poindron, Pascal, and Lindsay, David
- Abstract
Diffuser ses résultats de recherche est tout aussi important que le travail expérimental lui-même. Mais cette évidence se transforme bien souvent en une épreuve douloureuse lorsque vient le moment de la rédaction. Le chercheur débutant ou l'étudiant confronté à la rédaction de sa thèse ou de son premier article est alors assailli par une foule de questions : faut-il d’abord écrire le résumé ? Suivre l’ordre des différentes sections en commençant par l’introduction ? Cet ouvrage à l’usage des scientifiques en sciences biologiques, médicales, agronomiques et vétérinaires a été écrit pour décrypter les inconnues et pour répondre à toutes les questions qui assaillent les auteurs tout au long du processus de rédaction d’un article. L’ouvrage propose une manière d’aborder la rédaction en se concentrant sur la structure des articles plutôt que sur la grammaire et la syntaxe, en soulignant le rôle de l’hypothèse dans la construction de l’article. Il insiste également sur le fait que le style scientifique est avant tout celui de la logique.
- Published
- 2011
47. Guide de rédaction scientifique : L'hypothèse, clé de voûte de l'article scientifique
- Author
-
Lindsay, David, Poindron, Pascal, Lindsay, David, Lindsay, David, Poindron, Pascal, and Lindsay, David
- Abstract
Diffuser ses résultats de recherche est tout aussi important que le travail expérimental lui-même. Mais cette évidence se transforme bien souvent en une épreuve douloureuse lorsque vient le moment de la rédaction. Le chercheur débutant ou l'étudiant confronté à la rédaction de sa thèse ou de son premier article est alors assailli par une foule de questions : faut-il d’abord écrire le résumé ? Suivre l’ordre des différentes sections en commençant par l’introduction ? Cet ouvrage à l’usage des scientifiques en sciences biologiques, médicales, agronomiques et vétérinaires a été écrit pour décrypter les inconnues et pour répondre à toutes les questions qui assaillent les auteurs tout au long du processus de rédaction d’un article. L’ouvrage propose une manière d’aborder la rédaction en se concentrant sur la structure des articles plutôt que sur la grammaire et la syntaxe, en soulignant le rôle de l’hypothèse dans la construction de l’article. Il insiste également sur le fait que le style scientifique est avant tout celui de la logique.
- Published
- 2011
48. Guide de rédaction scientifique : L'hypothèse, clé de voûte de l'article scientifique
- Author
-
Lindsay, David, Poindron, Pascal, Lindsay, David, Lindsay, David, Poindron, Pascal, and Lindsay, David
- Abstract
Diffuser ses résultats de recherche est tout aussi important que le travail expérimental lui-même. Mais cette évidence se transforme bien souvent en une épreuve douloureuse lorsque vient le moment de la rédaction. Le chercheur débutant ou l'étudiant confronté à la rédaction de sa thèse ou de son premier article est alors assailli par une foule de questions : faut-il d’abord écrire le résumé ? Suivre l’ordre des différentes sections en commençant par l’introduction ? Cet ouvrage à l’usage des scientifiques en sciences biologiques, médicales, agronomiques et vétérinaires a été écrit pour décrypter les inconnues et pour répondre à toutes les questions qui assaillent les auteurs tout au long du processus de rédaction d’un article. L’ouvrage propose une manière d’aborder la rédaction en se concentrant sur la structure des articles plutôt que sur la grammaire et la syntaxe, en soulignant le rôle de l’hypothèse dans la construction de l’article. Il insiste également sur le fait que le style scientifique est avant tout celui de la logique.
- Published
- 2011
49. Guide de rédaction scientifique : L'hypothèse, clé de voûte de l'article scientifique
- Author
-
Lindsay, David, Poindron, Pascal, Lindsay, David, Lindsay, David, Poindron, Pascal, and Lindsay, David
- Abstract
Diffuser ses résultats de recherche est tout aussi important que le travail expérimental lui-même. Mais cette évidence se transforme bien souvent en une épreuve douloureuse lorsque vient le moment de la rédaction. Le chercheur débutant ou l'étudiant confronté à la rédaction de sa thèse ou de son premier article est alors assailli par une foule de questions : faut-il d’abord écrire le résumé ? Suivre l’ordre des différentes sections en commençant par l’introduction ? Cet ouvrage à l’usage des scientifiques en sciences biologiques, médicales, agronomiques et vétérinaires a été écrit pour décrypter les inconnues et pour répondre à toutes les questions qui assaillent les auteurs tout au long du processus de rédaction d’un article. L’ouvrage propose une manière d’aborder la rédaction en se concentrant sur la structure des articles plutôt que sur la grammaire et la syntaxe, en soulignant le rôle de l’hypothèse dans la construction de l’article. Il insiste également sur le fait que le style scientifique est avant tout celui de la logique.
- Published
- 2011
50. Guide de rédaction scientifique : L'hypothèse, clé de voûte de l'article scientifique
- Author
-
Lindsay, David, Poindron, Pascal, Lindsay, David, Lindsay, David, Poindron, Pascal, and Lindsay, David
- Abstract
Diffuser ses résultats de recherche est tout aussi important que le travail expérimental lui-même. Mais cette évidence se transforme bien souvent en une épreuve douloureuse lorsque vient le moment de la rédaction. Le chercheur débutant ou l'étudiant confronté à la rédaction de sa thèse ou de son premier article est alors assailli par une foule de questions : faut-il d’abord écrire le résumé ? Suivre l’ordre des différentes sections en commençant par l’introduction ? Cet ouvrage à l’usage des scientifiques en sciences biologiques, médicales, agronomiques et vétérinaires a été écrit pour décrypter les inconnues et pour répondre à toutes les questions qui assaillent les auteurs tout au long du processus de rédaction d’un article. L’ouvrage propose une manière d’aborder la rédaction en se concentrant sur la structure des articles plutôt que sur la grammaire et la syntaxe, en soulignant le rôle de l’hypothèse dans la construction de l’article. Il insiste également sur le fait que le style scientifique est avant tout celui de la logique.
- Published
- 2011
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