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Biomedical subjects

M A Taylor

Publications and source records attributed to M A Taylor.

At least 19 recordsLinked to original sources
PubMed2006

A computer model to simulate control of parasitic gastroenteritis in sheep on UK farms.

A computer model that simulates the population dynamics and epidemiology of three major species of parasitic nematodes of sheep found in the UK (Telodorsagia [Ostertagia] spp., Haemonchus spp. and Trichostrongylus spp.) is described. The model has been developed as a tool for veterinarians and advisors to aid in the implementation of integrated parasite control strategies designed to optimise anthelmintic usage and delay the development of resistance on UK farms. The model represents the parasite life cycle, flock dynamics and the response of individuals with different susceptible and resistant genotypes to the major broad-spectrum classes of anthelmintic available in the UK. Where possible, UK data have been used for the model parameters. The model allows worm control simulations on individual UK farms. Inputs include environmental and farm management variables which impact on the epidemiology of the disease, e.g. regional weather data; flock stocking rates; initial pasture larval contamination levels and species proportions; lambing dates; timing of flock movements to clean pastures; and removal of lambs during the year. Farm management data, as well as nematode egg outputs and grass larval counts, were collected from eight UK farms over a 1-year period for initial validation of the model outputs. The management data for each farm were used as inputs for each model run and model outputs for nematode egg counts from ewes and lambs were compared to the observed data for each farm. Statistical analysis of results shows a positive correlation for observed and simulated counts and regression analysis suggests an acceptable fit between the data. Comparison of observed and simulated outputs for resistance were possible for only one farm due to low numbers of worms developing in the laboratory tests. Additional studies will be necessary before resistance data can be reliably compared. Further validation studies are proposed to ensure that the model is robust and applicable across a diverse range of farm types. The model will be used to demonstrate the advantage, in terms of delaying resistance development, of current guidelines for anthelmintic use and management practices for worm control in sheep.

Animals↗
PubMed2006

The detection of anthelmintic resistance in nematodes of veterinary importance.

Before revised World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines on the detection of anthelmintic resistance can be produced, validation of modified and new methods is required in laboratories in different parts of the world. There is a great need for improved methods of detection of anthelmintic resistance particularly for the detection of macrocyclic lactone resistance and for the detection of resistant nematodes in cattle. Therefore, revised and new methods are provided here for the detection of anthelmintic resistance in nematodes of ruminants, horses and pigs as a basis for discussion and with the purpose that they are evaluated internationally to establish whether they could in the future be recommended by the WAAVP. The interpretation of the faecal egg count reduction test has been modified and suggestions given on its use with persistent anthelmintics and continuous release devices. An egg hatch test for benzimidazole (BZ) resistance is described. A microagar larval development test for the detection of benzimidazole and levamisole resistance provides third stage larvae for the identification of resistant worms. The sensitivity of these two tests can be increased by using discriminating doses rather than LD(50) values. Details are given of a PCR based test for the analysis of benzimidazole resistance in strongyles of sheep and goats, horses and cattle. Although promising for ruminant trichostrongyles, quantitative determination of gene frequency using real time PCR requires further development before PCR tests will be used in the field. Apart from faecal egg count reduction tests there are currently no satisfactory tests for macrocylic lactone resistance despite the great importance of this subject. Except for treatment and slaughter trials there are no validated tests for fasciolicide resistance or for the detection of resistance in cestodes.

Animals↗
PubMed2006

Randomized, multi-center trial of two hypo-energetic diets in obese subjects: high- versus low-fat content.

OBJECTIVE: To investigate whether a hypo-energetic low-fat diet is superior to a hypo-energetic high-fat diet for the treatment of obesity. DESIGN: Open-label, 10-week dietary intervention comparing two hypo-energetic (-600 kcal/day) diets with a fat energy percent of 20-25 or 40-45. SUBJECTS: Obese (BMI >or=30 kg/m(2)) adult subjects (n = 771), from eight European centers. MEASUREMENTS: Body weight loss, dropout rates, proportion of subjects who lost more than 10% of initial body weight, blood lipid profile, insulin and glucose. RESULTS: The dietary fat energy percent was 25% in the low-fat group and 40% in the high-fat group (mean difference: 16 (95% confidence interval (CI) 15-17)%). Average weight loss was 6.9 kg in the low-fat group and 6.6 kg in the high-fat group (mean difference: 0.3 (95% CI -0.2 to 0.8) kg). Dropout was 13.6% (n = 53) in the low-fat group and 18.3% (n = 70) in the high-fat group (P=0.001). Among completers, more subjects lost >10% in the low-fat group than in the high-fat group ((20.8%, n = 70) versus (14.7%, n = 46), P = 0.02). Fasting plasma total, low-density lipoprotein- and high-density lipoprotein-cholesterol decreased in both groups, but more so in the low-fat group than in the high-fat group. Fasting plasma insulin and glucose were lowered equally by both diets. CONCLUSIONS: The low-fat diet produced similar mean weight loss as the high-fat diet, but resulted in more subjects losing >10% of initial body weight and fewer dropouts. Both diets produced favorable changes in fasting blood lipids, insulin and glucose.

Adult↗
PubMed2005

Characterisation of lesional infiltrates of dendritic cells and T cell subtypes during primary infestation of sheep with Psoroptes ovis, the sheep scab mite.

Earlier studies of cattle and sheep have demonstrated that Psoroptes ovis infestations provoke an intense immunoinflammatory response dominated by eosinophils accompanied by a substantial infiltrate of lymphocytes. However, the kinetics of the lymphocyte response and the subtypes involved have not been characterised. We employed two groups of sheep to investigate the early (1-21 days) and later (21-63 days) infiltration of lymphocyte subpopulations and dendritic cells in primary infestations of sheep with P. ovis. Immunohistochemistry indicated that by 4 days after infestation numbers of CD4+ and CD45RA+ cells in lesional skin had increased significantly (P<0.03 and P<0.005, respectively) and that a significant increase in gammadelta T cells and dendritic cells (CD1b+) had occurred by 8 days (P<0.02 and P<0.01, respectively). Numbers of lymphocyte and dendritic cells declined from 49 to 63 days after infestation. Our observations suggest that mite-derived products exert a profound influence on the early recruitment of lymphocytes that may significantly influence the genesis of the adaptive immune response.

Animals↗
PubMed2005

Agrobacterium-mediated transformation of Solanum phureja.

A population of transgenic plants was produced by the transformation of internodal explants of Solanum phureja, DB337/37 (the cultivar Mayan Gold) using an Agrobacterium tumefaciens LBA4404-based vector containing a phytoene synthase gene (crtB). The regeneration strategy utilised a two-step protocol, with a 12-day callus induction stage mediated by 1.07 microM alpha-napthaleneacetic acid (NAA), 7.10 microM zeatin riboside and 0.06 microM gibberellic acid (GA3), followed by a prolonged (up to 90 day) shoot induction stage on medium containing 0.11 microM NAA, 7.10 microM zeatin riboside and 0.06 microM GA3 supplemented with kanamycin at 50 mg l(-1) as the selection agent. Southern analysis of the transgenic population revealed that the transgene copy number varied between one and five in the lines tested. Northern blot analysis showed significant expression of the introduced crtB gene in some lines during tuber development. Cytological analysis of the material showed a high incidence of chromosome doubling in the transgenic population with over 80% of all lines tested having doubled their chromosome complement during the transformation process.

Agrobacterium tumefaciens↗
PubMed2004

Carotenogenesis during tuber development and storage in potato.

Germplasm of Solanum tuberosum and Solanum phureja exhibit a wide (over 20-fold) variation in tuber carotenoid content. The levels of carotenoids during tuber development and storage were compared in a high carotenoid-accumulating S. phureja accession (DB375\1) with two S. tuberosum cultivars (Pentland Javelin and Desiree) that accumulate lower levels of tuber carotenoid. On a dry weight basis, total carotenoid levels were at a maximum early in tuber development. However, in the S. phureja accession, carotenoid levels remained at a high level throughout tuber development, whereas in the S. tuberosum accessions, carotenoid content decreased as dry weight increased. The carotenoid profiles of tissues during tuber development were analysed in greater detail by reverse phase HPLC. In S. phureja tubers at maturity the major carotenoids were zeaxanthin, antheraxanthin, and violaxanthin. Following 9 months storage at 4 degrees C the levels of zeaxanthin and antheraxanthin decreased, whereas the level of lutein increased; overall, however, there was only a small decrease in total carotenoid content. In order to explore the reasons for the wide variation in tuber carotenoid content, the expression patterns of the major genes encoding the enzymes of the carotenoid biosynthetic pathway were compared. Significant differences in the profiles were detected, suggesting that transcriptional control or mRNA stability gives rise to the large differences in tuber carotenoid content. In particular, there was an inverse trend between the level of zeaxanthin epoxidase transcript level and tuber carotenoid content in a range of potato germplasm, giving rise to an hypothesis for the regulation of carotenogenesis in potato tubers.

Base Sequence↗
PubMed2004

Growth and pathogenicity of isolates of the fungus Metarhizium anisopliae against the parasitic mite, Psoroptes ovis: effects of temperature and formulation.

Psoroptes mites (Acari: Psoroptidae) are important ectoparasites of mammals, and are of particular economic significance as the agents of mange in sheep. To be effective against mites, putative fungal biocontrol agents must be able to operate at the relatively high temperatures and humidities found at the sheep skin surface. To consider this, the growth rates of different isolates of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin (Deuteromycotina: Hyphomycetes) were compared and the pathogenicity of these isolates against Psoroptes derived from rabbits (Psoroptes ovis Hering, syn P cuniculi) were evaluated at temperatures between 28 degrees C and 40 degrees C, and when formulated in either Tween 80 or silicone oil. For this study four multi-conidia, arthropod-derived, isolates of M anisopliae were used: from the USA, France, Denmark and Brazil. One single-conidia culture derived from the US isolate was also included in the investigation. Fungal growth was higher at the lower temperatures and none of the isolates grew at 40 degrees C. The growth of the US and single-conidia isolate declined markedly with temperature. In contrast, the Danish, French and Brazilian isolates grew almost as well at 32 degrees C and 35 degrees C as at 28 degrees C and 30 degrees C. The French and Brazilian isolates showed some growth at 37.5 degrees C but the Danish and US isolates did not. The number of fatal infections which resulted from exposure of mites to the fungal isolates was also strongly influenced by temperature. At 30 degrees C all isolates gave between 70 and 90% infection. The number of infections declined with increasing temperature and no infections were seen at 40 degrees C. However, the French and Danish isolates of M anisopliae gave higher numbers of infections than the other isolates at elevated temperatures. When formulated in silicone oil, significantly higher levels of infection were obtained than when formulated in Tween 80, even at the relatively high temperature of 37.5 degrees C. It is suggested that high-temperature adapted isolates of M anisopliae formulated in silicone oil offer good candidates as control agents under the conditions found at the sheep skin surface.

Animals↗
PubMed2004

Early innate and longer-term adaptive cutaneous immunoinflammatory responses during primary infestation with the sheep scab mite, Psoroptes ovis.

Clinical observation has indicated that Psoroptes ovis mites provoke cutaneous inflammation within hours of experimental infestation, but the nature of this reaction has not been described. After infestation of naive sheep with ovigerous P. ovis mites, significant influxes of eosinophils (P<0.004) and neutrophils (P<0.001) were detected within 24 h. A significant (P<0.001) increase in mast cell numbers was observed by 96 h post-infestation. In addition, marked degenerative and proliferative epidermal lesions were evident 24 and 96 h, respectively, after infestation. The influence of the later, adaptive response on the cellular infiltrate at the advancing margin of the lesion and the original site of infestation was also monitored. Mast cell numbers were greatest at 21 days while recruitment of eosinophils and neutrophils was maximal 63 days after infestation. Lesional severity was particularly pronounced from 42 to 63 days after infestation, but significant resolution had occurred by 84 days. Pathological changes at the advancing margin of the lesion were more severe than at the initial site of infestation, and this was reflected by the numbers of mites present. These data suggest that P. ovis elicits an early innate cutaneous response that is subsequently augmented by the development of an adaptive immune response, the intensity of which corresponds to the local population density of mites.

Animals↗
PubMed2004

Assessment of fecal output in patients receiving enteral tube feeding: validation of a novel chart.

OBJECTIVE: To develop a practical, valid and reliable chart to assist in the accurate visual characterization of fecal output in patients receiving enteral tube feeding (ETF). DESIGN: A chart incorporating verbal and pictorial descriptors of fecal output was developed. Validity and reliability were assessed by a questionnaire survey of health professionals and a clinical study of patients commencing ETF. Content validity was assessed from the results of the questionnaire, construct validity by contrasting groups analysis, concurrent validity by comparison of the chart with actual fecal weight and inter-rater reliability by independent characterization of the same fecal sample by two nurses. SETTING: St George's Hospital, London, UK. SUBJECTS: In all, 35 health professionals completed a questionnaire with respect to the chart. The chart was then used to monitor fecal output in 36 patients commencing ETF for a total of 171 patient-days, during which time nurses used the chart to characterize 269 fecal samples, of which 59 were subsequently weighed. RESULTS: The results of the questionnaire suggested good content validity. The chart demonstrated statistically significant differences in fecal frequency, fecal consistency, fecal score and incidence of diarrhea for contrasting patient groups expected to have different fecal output (P < 0.05). The inter-rater reliability was almost perfect for fecal consistency (95% agreement, kappa = 0.91) and substantial for fecal weight (83%, kappa = 0.75). In all, 83% of fecal samples were assigned to the correct weight category (kappa = 0.75). CONCLUSION: The chart has good content, construct and concurrent validity and inter-rater reliability, and is suitable for both research and clinical use. SPONSORSHIP: This research was jointly supported by King's College London and Nestlé, UK.

Diarrhea↗
PubMed2004

Regular meal frequency creates more appropriate insulin sensitivity and lipid profiles compared with irregular meal frequency in healthy lean women.

OBJECTIVE: To investigate the impact of irregular meal frequency on circulating lipids, insulin, glucose and uric acid concentrations which are known cardiovascular risk factors. DESIGN: A randomised crossover dietary intervention study. SETTING: Nottingham, UK--Healthy free-living women. SUBJECTS: A total of nine lean healthy women aged 18-42 y recruited via advertisement. INTERVENTION: A randomised crossover trial with two phases of 14 days each. In Phase 1, subjects consumed their normal diet on either 6 occasions per day (regular) or by following a variable meal frequency (3-9 meals/day, irregular). In Phase 2, subjects followed the alternative meal pattern to that followed in Phase 1, after a 2-week (wash-out) period. Subjects were asked to come to the laboratory after an overnight fast at the start and end of each phase. Blood samples were taken for measurement of circulating glucose, lipids, insulin and uric acid concentrations before and for 3 h after consumption of a high-carbohydrate test meal. RESULTS: Fasting glucose and insulin values were not affected by meal frequency, but peak insulin and AUC of insulin responses to the test meal were higher after the irregular compared to the regular eating patterns (P < 0.01). The irregular meal frequency was associated with higher fasting total (P < 0.01) and LDL (P < 0.05) cholesterol. CONCLUSION: The irregular meal frequency appears to produce a degree of insulin resistance and higher fasting lipid profiles, which may indicate a deleterious effect on these cardiovascular risk factors. SPONSORSHIP: : The Ministry of Health and Medical Education, IR Iran.

Adolescent↗
PubMed2004

Decreased thermic effect of food after an irregular compared with a regular meal pattern in healthy lean women.

OBJECTIVES: To investigate the impact of irregular meal frequency on body weight, energy intake, appetite and resting energy expenditure in healthy lean women. DESIGN: Nine healthy lean women aged 18-42 y participated in a randomised crossover trial consisting of three phases over a total of 43 days. Subjects attended the laboratory at the start and end of phases 1 and 3. In Phase 1 (14 days), subjects were asked to consume similar things as normal, but either on 6 occasions per day (regular meal pattern) or follow a variable predetermined meal frequency (between 3 and 9 meals/day) with the same total number of meals over the week. In Phase 2 (14 days), subjects continued their normal diet as a wash-out period. In Phase 3 (14 days), subjects followed the alternative meal pattern to that followed in Phase 1. Subjects recorded their food intake for three predetermined days during the irregular period when they were eating 9, 3 and 6 meals/day. They also recorded their food intake on the corresponding days during the regular meal pattern period. Subjects fasted overnight prior to each laboratory visit, at which fasting resting metabolic rate (RMR) was measured by open-circuit indirect calorimetry. Postprandial metabolic rate was then measured for 3 h after the consumption of a milkshake test meal (50% CHO, 15% protein and 35% fat of energy content). Subjects rated appetite before and after the test meal. RESULTS: There were no significant differences in body weight and 3-day mean energy intake between the regular and irregular meal pattern. In the irregular period, the mean energy intake on the day when 9 meals were eaten was significantly greater than when 6 or 3 meals were consumed (P=0.0001). There was no significant difference between the 3 days of the regular meal pattern. Subjective appetite measurement showed no significant differences before and after the test meal in all visits. Fasting RMR showed no significant differences over the experiment. The overall thermic effect of food (TEF) over the 3 h after the test meal was significantly lower after the irregular meal pattern (P=0.003). CONCLUSION: Irregular meal frequency led to a lower postprandial energy expenditure compared with the regular meal frequency, while the mean energy intake was not significantly different between the two. The reduced TEF with the irregular meal frequency may lead to weight gain in the long term.

Adolescent↗
PubMed2003

Histopathological observations on the activity of diclazuril (Vecoxan) against the endogenous stages of Eimeria crandallis in sheep.

Doses of sporulated oocysts of Eimeria crandallis were administered to 60 housed lambs aged 3-4 weeks that had been raised coccidia-free. Thirty of the lambs were medicated with diclazuril at intervals over a 20-day period post-infection with the remaining lambs serving as untreated controls. Lambs were euthanased between 5 and 22 days post-infection (dpi) and sections of the small intestine and caecum examined histologically. Untreated lambs showed loss of surface epithelial cells and villous atrophy associated with first-generation meronts, crypt destruction and crypt hyperplasia associated with pro-gamont stages. Diclazuril appeared to have a direct effect on several stages of the parasite life cycle, in particular, the large first-generation meront. Indications were that the drug also had an effect on second-generation meronts and gamont stages. Therapeutic benefits of diclazuril treatment appeared greatest when given early in the infection before damage to the intestine occurs although removal of coccidial stages did appear to reduce the pathology of the disease.

Animals↗
PubMed2003

A physiological and biochemical model for digestion in the ectoparasitic mite, Psoroptes ovis (Acari: Psoroptidae).

Mites are an important group of arthropod pests affecting crops, animals and humans. Despite this, detailed physiological studies on these organisms remain sparse due largely to their small size. Unifying models are required to draw together the diverse information from studies on different groups and species. This paper describes a model for digestion in the parasitic mite, Psoroptes ovis, the causative agent of psoroptic mange or sheep scab disease. The limited information about this species is supplemented with data from other acarines, especially house dust mites and ticks. We review the range of enzymes and allergens found in mites and consider their possible roles in digestion in mites, generally and in particular, P. ovis. Histological studies, enzyme biochemistry and molecular biology and experimental evidence suggest that P. ovis utilises a digestive system reliant upon acid peptidases functioning in a largely intracellular environment. The actions of the digestive enzymes are supplemented by the involvement of bacteria as potential direct and indirect sources of nutrition. It is possible that some extra-corporeal digestion also takes place. The interaction of bacteria and digestive enzymes on the skin surface of the sheep may be responsible for the excessive pathological reactions evident in clinical sheep scab.

Animals↗
PubMed2003

Temporal pattern of isotype-specific antibody responses in primary and challenge infestations of sheep with Psoroptes ovis--the sheep scab mite.

In sheep Psoroptes ovis provokes an allergic dermatitis with significant P. ovis antigen-specific IgE responses. The kinetics of the IgE response to primary and challenge infestations of P. ovis were reported earlier [Parasite Immunol. 22 (2000) 407]. The present study examines IgG, IgM and IgA responses to primary and challenge infestations of P. ovis and the profile of antigens/allergens reacting with IgG and IgE antibodies. Antigen-specific enzyme-linked immunosorbent assays (ELISAs) demonstrate that primary infestations elicited significant increases in levels of IgG and IgM but not IgA antibodies. IgG and IgM responses to primary and challenge infestations were not significantly different. Western blots of reduced P. ovis proteins indicate that IgG antibodies reacted with five major antigens following primary infestation and only three of these after challenge infestation. IgE antibodies bound to three major and five minor allergens after primary infestation and two additional minor allergens after challenge infestation. Immunodominant antigens >100 and <15 kDa and allergens >100 kDa were most consistent in stimulating substantial IgG and IgE antibody responses, respectively. These antigens/allergens may be exploited in immunodiagnosis and modulation of the host immune response.

Allergens↗
PubMed2003

Defining and reporting diarrhoea during enteral tube feeding: do health professionals agree?

INTRODUCTION: The criteria used to define diarrhoea during enteral tube feeding (ETF) and the interrater reliability of nursing staff reporting it in clinical practice has not been investigated. METHODS: A structured questionnaire was sent to a cohort of dietitians, specialist stroke nurses, intensive therapy unit (ITU) nurses and consultant gastroenterologists regarding their criteria for defining ETF diarrhoea. In a clinical study, nursing staff independently inspected faeces from patients receiving ETF and were asked whether they considered the patient to have diarrhoea. RESULTS: Thirty-five healthcare workers responded to the questionnaire. Faecal frequency, faecal consistency and faecal quantity were all considered important criteria in defining ETF diarrhoea. Faecal frequency was considered more important than consistency and quantity (P = 0.048), although not all professional groups agreed on the order of importance. In the clinical study, nursing staff agreed on the presence or absence of diarrhoea on 75% of occasions, with agreement being only fairly reliable (kappa = 0.48). CONCLUSION: Healthcare workers use a range of criteria to define ETF diarrhoea, but may not agree on the importance of each criteria. In order to prevent confusion between professional groups, healthcare workers should be encouraged to describe faecal characteristics rather than rely on the term 'diarrhoea'.

Diarrhea↗