Veterinary Science Collected Works - Research Publications
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ItemSpatial and temporal distribution of foot and mouth disease outbreaks in Amhara region of Ethiopia in the period 1999 to 2016(BMC, 2020-06-09)BACKGROUND: Foot and mouth disease (FMD) is an economically important trans-boundary viral disease of cloven-hoofed animals. It is caused by FMD virus, which belongs to the genus Aphthovirus and family Picornaviridae. FMD is a well-established endemic disease in Ethiopia since it was first detected in 1957. This retrospective study was carried out to identify the spatial and temporal distribution of FMD outbreaks in Amhara region of Ethiopia using 18 years (January 1999-December 2016) reported outbreak data. RESULTS: A total of 636 FMD outbreaks were reported in Amhara region of Ethiopia between 1999 and 2016 with an average and median of 35 and 13 outbreaks per year respectively. In this period, FMD was reported at least once in 58.5% of the districts (n = 79) and in all administrative zones of the region (n = 10). The average district level incidence of FMD outbreaks was 4.68 per 18 years (0.26 per district year). It recurs in a district as epidemic, on average in 5.86 years period. The incidence differed between administrative zones, being the lowest in East Gojjam and highest in North Shewa. The occurrence of FMD outbreaks was found to be seasonal with peak outbreaks in March and a low in August. The long-term trend of FMD outbreaks indicates a slight, but statistically significant (p < 0.001) decrease over the study period. CONCLUSION: FMD occurred in all zones of the region and showed statistically significant decrease in the long-term trend. Numbers of outbreaks were relatively higher during dry season. The spatial and temporal distribution identified in this study should be considered in controlling the disease. As unregulated and frequent animal movements are the likely causes of high outbreak occurrence during the dry season, animal movement regulations should be considered for the long-term control of FMD.
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ItemA disrupted transsulphuration pathway results in accumulation of redox metabolites and induction of gametocytogenesis in malaria(NATURE PORTFOLIO, 2017-01-16)Intra-erythrocytic growth of malaria parasite is known to induce redox stress. In addition to haem degradation which generates reactive oxygen species (ROS), the parasite is also thought to efflux redox active homocysteine. To understand the basis underlying accumulation of homocysteine, we have examined the transsulphuration (TS) pathway in the parasite, which is known to convert homocysteine to cysteine in higher eukaryotes. Our bioinformatic analysis revealed absence of key enzymes in the biosynthesis of cysteine namely cystathionine-β-synthase and cystathionine-γ-lyase in the parasite. Using mass spectrometry, we confirmed the absence of cystathionine, which is formed by enzymatic conversion of homocysteine thereby confirming truncation of TS pathway. We also quantitated levels of glutathione and homocysteine in infected erythrocytes and its spent medium. Our results showed increase in levels of these metabolites intracellularly and in culture supernatants. Our results provide a mechanistic basis for the long-known occurrence of hyperhomocysteinemia in malaria. Most importantly we find that homocysteine induces the transcription factor implicated in gametocytogenesis namely AP2-G and consequently triggers sexual stage conversion. We confirmed this observation both in vitro using Plasmodium falciparum cultures, and in vivo in the mouse model of malaria. Our study implicates homocysteine as a potential physiological trigger of gametocytogenesis.
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ItemInsights into physiological roles of unique metabolites released from Plasmodium-infected RBCs and their potential as clinical biomarkers for malaria(NATURE PORTFOLIO, 2019-02-27)Plasmodium sp. are obligate intracellular parasites that derive most of their nutrients from their host meaning the metabolic circuitry of both are intricately linked. We employed untargeted, global mass spectrometry to identify metabolites present in the culture supernatants of P. falciparum-infected red blood cells synchronized at ring, trophozoite and schizont developmental stages. This revealed a temporal regulation in release of a distinct set of metabolites compared with supernatants of non-infected red blood cells. Of the distinct metabolites we identified pipecolic acid to be abundantly present in parasite lysate, infected red blood cells and infected culture supernatant. Further, we performed targeted metabolomics to quantify pipecolic acid concentrations in both the supernatants of red blood cells infected with P. falciparum, as well as in the plasma and infected RBCs of P. berghei-infected mice. Measurable and significant hyperpipecolatemia suggest that pipecolic acid has the potential to be a diagnostic marker for malaria.
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ItemNo Preview Available"I Had No Idea That Other People in the World Thought Differently to Me": Ethical Challenges in Small Animal Veterinary Practice and Implications for Ethics Support and Education(University of Toronto Press, 2020-12-01)Although veterinarians encounter ethical challenges in their everyday practice, few studies have examined how they make sense of and respond to them. This research used semi-structured interviews and a qualitative methodology (phenomenological and constructivist/interpretivist approaches) to explore ethical challenges experienced by seven small animal city veterinarians and their ethical decision-making strategies. Thematic analysis of the interview transcripts identified four broad ethical issues: The first concerned disagreements about the best interests of the animal; the second centered on clinical uncertainty about the most appropriate treatment for the animal; the third involved factors influencing ethical reasoning and decision making; and the fourth concerned how ethics education might prepare veterinary students for future ethical decision making. An overarching theme identified in the analysis was one of enormous personal distress. Furthermore, a sense of veterinarians being interested in how others might think and feel about ethical challenges came through in the data. The results give insight into how veterinarians experience and respond to ethical challenges. The research also provides empirical information about everyday practice to inform future education in ethics and ethical decision making for veterinary students.
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ItemExpression of HIF-1α and VEGF in feline mammary gland carcinomas: association with pathological characteristics and clinical outcomes(BMC, 2020-05-06)BACKGROUND: The microenvironment within solid malignant tumors, including feline mammary gland carcinomas (FMGCs), is commonly hypoxic, possibly due to the lack of functional blood vessels in rapidly proliferating neoplastic tissue. Malignant cells can undergo genetic and adaptive changes that prevent them from dying due to oxygen deprivation through expressions of hypoxia-inducible factor 1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF). Therefore, HIF-1α and VEGF are ideal biomarkers for cancer therapy and prognostic evaluation. The aims of this study were to evaluate the expression of HIF-1α and VEGF in feline mammary carcinomas and analyze their correlations with clinical and pathological factors, such as clinical stage, histologic grading, regional metastasis, and overall survival rate. RESULTS: Paraffin-embedded tissue samples collected from 72 cats with FMGCs were retrospectively studied. Histologic pattern and histologic grading (Elston and Ellis grading system) of these FMGCs were determined. Our data indicated that grade II tubulopapillary carcinomas (43/72, 59.7%) prevailed in this study, and most FMCGs showed apparent necrosis, squamous metaplasia, and intratumoral stromal response. According to the results of immunohistochemical (IHC) stainings performed in tissue microarrays (TMAs), HIF-1α and VEGF overexpressions were respectively noted in 69.4% (50/72) and 77.8% (56/72) of FMGC cases. Chi-square test showed no correlation of HIF-1α overexpression with clinical and pathological factors. VEGF overexpression was significantly correlated with histologic pattern (p = 0.021), stromal response (p = 0.048), squamous metaplasia (p = 0.001), and lymphovascular invasion (p = 0.007). However, neither HIF-1α nor VEGF overexpression was correlated with histologic grading and metastasis. Of 38 cats with 1-year follow-up, IHC stainings of HIF-1α and VEGF were performed on whole tissue sections. The results showed that overexpression of HIF-1α was significantly correlated with the overall survival rate (p < 0.05) (log-rank test), whereas there was no significant correlation between VEGF overexpression and overall survival rate. CONCLUSIONS: This study suggests that the overexpression of HIF-1α may indicate poor prognosis/overall survival rate in cats with FMGCs. Developing compounds that inhibit HIF-1α may be a potential approach to FMGC treatment.
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ItemInput-to-state stability analysis via averaging for parameterized discrete-time systems(Watam Press, 2010-12-15)The paper studies semi-global practical input-to-state stability (SGP-ISS) of a parameterized family of discrete-time systems that may arise when an approximate discrete-time model of a sampled-data system with disturbances is used for controller design. It is shown under appropriate conditions that if the solutions of the time varying family of discrete-time systems with disturbances converge uniformly on compact time intervals to the solutions of the average family of discrete-time systems, then ISS of the average family of systems implies SGP-ISS of the original family of systems. A trajectory based approach is utilized to establish the main result.
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ItemIn vitro antidiabetic effects of selected fruits and vegetables against glycosidase and aldose reductase.(Wiley, 2015-11)In vitro antidiabetic effect of fruits and vegetables with reports as folk remedies were investigated. The antidiabetic effects were evaluated by comparing the inhibitory properties of α-glycosidase, aldose reductase, and antioxidant activity. The results indicated that lychee extract exhibited the best dose-dependent inhibitory activity against α-glycosidase with IC 50 of 10.4 mg/mL, and lemon peel extract exhibited aldose reductase inhibitory potential with IC 50 value at 3.63 mg/mL. Besides, the result also showed that the inhibitory effects of blueberry and plum against α-glycosidase were strong among the fruits samples. Bitter gourd and eggplant demonstrated significant inhibitory potential against aldose reductase, with IC 50 values at 8.55 mg/mL and 8.06 mg/mL, respectively. The result from correlation analysis part showed that the antioxidant activities of selected fruits and vegetables were found related to their health beneficial effects, as there was positive correlations between total flavonoids content (TFC) and aldose reductase inhibitory activity (r (2) = 0.556).
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ItemRenewal ecology: conservation for the Anthropocene(WILEY, 2017-09)The global scale and rapidity of environmental change is challenging ecologists to reimagine their theoretical principles and management practices. Increasingly, historical ecological conditions are inadequate targets for restoration ecology, geographically circumscribed nature reserves are incapable of protecting all biodiversity, and the precautionary principle applied to management interventions no longer ensures avoidance of ecological harm. In addition, human responses to global environmental changes, such as migration, building of protective infrastructures, and land use change, are having their own negative environmental impacts. We use examples from wildlands, urban, and degraded environments, as well as marine and freshwater ecosystems, to show that human adaptation responses to rapid ecological change can be explicitly designed to benefit biodiversity. This approach, which we call “renewal ecology,” is based on acceptance that environmental change will have transformative effects on coupled human and natural systems and recognizes the need to harmonize biodiversity with human infrastructure, for the benefit of both.
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ItemHigh-throughput physiological phenotyping and screening system for the characterization of plant-environment interactions(WILEY, 2017-02)We present a simple and effective high-throughput experimental platform for simultaneous and continuous monitoring of water relations in the soil-plant-atmosphere continuum of numerous plants under dynamic environmental conditions. This system provides a simultaneously measured, detailed physiological response profile for each plant in the array, over time periods ranging from a few minutes to the entire growing season, under normal, stress and recovery conditions and at any phenological stage. Three probes for each pot in the array and a specially designed algorithm enable detailed water-relations characterization of whole-plant transpiration, biomass gain, stomatal conductance and root flux. They also enable quantitative calculation of the whole plant water-use efficiency and relative water content at high resolution under dynamic soil and atmospheric conditions. The system has no moving parts and can fit into many growing environments. A screening of 65 introgression lines of a wild tomato species (Solanum pennellii) crossed with cultivated tomato (S. lycopersicum), using our system and conventional gas-exchange tools, confirmed the accuracy of the system as well as its diagnostic capabilities. The use of this high-throughput diagnostic screening method is discussed in light of the gaps in our understanding of the genetic regulation of whole-plant performance, particularly under abiotic stress.
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ItemNo Preview AvailableTropical and extratropical-origin storm wave types and their influence on the East Australian longshore sand transport system under a changing climate(AMER GEOPHYSICAL UNION, 2016-07)Abstract Tropical expansion is potentially an amplifier of coastal change in the subtropics, through directional wave climate shifts. The storm wave climate and directional wave power distribution along the Southeast Australian Shelf (SEAS) is investigated with respect to tropical extent. Forty years of storm wave observations from nine midshelf wave buoys are evaluated using synoptic storm wave typing. A robust latitudinal and along‐shelf gradient in storm wave types and wave propagation patterns exists. The tropical origin storms produce a shore‐normal propagation pattern along the SEAS, reduce the connectivity of coastal compartments through minor headland bypassing events or episodically reversing the net northward transport. In contrast, the extratropical origin storms produce a shore‐oblique propagation pattern from the Southern Tasman to the Coral Sea, and are an important control on the connectivity of regional longshore sand transport through episodic major headland bypassing events between compartments, and the maintenance of down‐drift coastlines in dynamic equilibrium. Future climate change projections indicate that the recent trend in the expansion of the latitudinal extent of the tropics in the south‐west Pacific region will continue throughout this century. The combined impacts of a projected 2.5° poleward shift on the storm wave climate is a significant reduction in net northward longshore sand transport and the efficiency of headland bypassing events. On the North and Central Coasts of New South Wales we project a ∼30% reduction in longshore sand transport for the dominant extratropical‐origin storm events, together with a ∼5% increase in reversed (net southward) longshore sand transport for tropical‐origin storm events.