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Biomedical subjects

D E Jacobs

Publications and source records attributed to D E Jacobs.

At least 55 records · Page 3Linked to original sources
PubMed1995

Evaluation of doramectin in a programme for season-long control of parasitic gastroenteritis in calves.

Doramectin was used in a strategic programme for the prevention of parasitic gastroenteritis in first season grazing calves. Three groups of nine calves were used: group 1 was left untreated, group 2 was treated with doramectin at 0.2 mg/kg at turnout and again eight weeks later, and group 3 was treated with 0.2 mg/kg ivermectin at three, eight and 13 weeks after turnout. Both treatment programmes prevented the gastroenteritis which occurred in the controls. The growth rates of the treated calves were superior, and their faecal egg output, and serum pepsinogen and gastrin concentrations were all substantially lower than those of the control calves. The numbers of Ostertagia species larvae on the pastures grazed by the treated calves were also lower than on the pastures grazed by the control calves.

Animals↗
PubMed1995

An evaluation of abamectin given at turnout and six weeks after turnout for the control of nematode infections in calves.

Two groups of 16 set-stocked calves were used to evaluate a new strategy for the prevention of parasitic bronchitis and parasitic gastroenteritis. One group was left untreated while the calves in the other were treated with abamectin at 0.2 mg/kg at turnout and again six weeks later. The treatment prevented the output of nematode eggs and lungworm larvae in faeces for at least 70 days. The number of infective larvae subsequently appearing on the pasture was reduced by 90.2 per cent and the infectivity of the pasture (as monitored by tracer calves) by 96.0 to 99.8 per cent in the case of Dictyocaulus viviparus, 88.2 to 99.2 per cent for Ostertagia ostertagi and 69.3 to 98.1 per cent for Cooperia oncophora. Parasitic bronchitis occurred in the control calves and both bronchitis and gastroenteritis in the tracer calves grazing the paddock grazed by the control calves, but no disease occurred either in any of the calves treated with abamectin or in the tracer calves grazing the paddock grazed by these calves.

Animal Feed↗
PubMed1995

A side-by-side comparison of dust collection methods for sampling lead-contaminated house dust.

The Environmental Protection Agency is required to set a standard for lead-contaminated house dust, but whether dust lead loading (micrograms/ft2) or concentration (micrograms/g) is more predictive of children's blood lead levels, which dust collection method should be used, and which surfaces should be sampled are unknown. Using a random sample of sequential births, we enrolled 205 urban children, 12 to 30 months of age, who had lived in the same house since at least 6 months of age. Samples of dust were obtained from predetermined surfaces in each child's residence using a wipe method and two vacuum methods, the Baltimore repair and maintenance method (BRM) and the dust vacuum method (DVM). Other potential sources of environmental exposure also were analyzed for lead, including soil, water, and paint. In general, dust lead loading is more predictive of children's blood lead levels than is dust lead concentration. Dust lead loading as measured with the BRM sampler explained more of the variation in children's blood lead levels than did wipe loading and DVM loading (13.7, 10.1, and 5.9%, respectively, adjusted for other significant predictors). The partial correlation between BRM lead loading and children's blood lead was significantly different than that for DVM lead loading, but it was not significantly different than that for wipe lead loading. Of the four surfaces measured, noncarpeted floors and interior window sills or wells were significantly associated with children's blood lead levels in multiple regression models. These data indicate that dust lead loading is more predictive of children's blood lead levels than is dust lead concentration and that, to determine if a housing unit is safe for children, noncarpeted floors and interior window sills or window wells should be measured using either the BRM or wipe sampling method.

Air Pollution, Indoor↗
PubMed1994

Studies on the control of Toxocara canis in breeding kennels.

The control of Toxocara canis was investigated in naturally infected unweaned puppies. Anthelmintic treatments were administered to three litters of pups at 2, 4 and 6 weeks of age. When either a new combination anthelmintic containing febantel, pyrantel embonate and praziquantel or fenbendazole was used, the faecal egg output over the first 7 weeks of life was reduced by more than 80% and worm burdens by over 90%. In contrast, piperazine adipate had no appreciable effect on T. canis egg output, even though worm burdens were reduced by 86% by 7 weeks of age. In a further trial using three litters, the worm burden of pups treated with the combination anthelmintic was profiled before and after the 2 week dose and after the 4 week dose. Although worm numbers were substantially reduced by treatment, there was evidence of significant reinfection taking place throughout the control programme. It is concluded that more potent anthelmintics can provide longer term benefits by reducing the numbers of T. canis eggs shed into the environment, but that multiple dosing remains essential for this purpose.

Aging↗
PubMed1994

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of anthelmintics for dogs and cats.

Guidelines have been designed to assist in the planning, operation and interpretation of studies for the assessment of the efficacy of drugs against helminth parasites of dogs and cats. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on the selection of animals, housing, feeding, dose-titration, confirmatory and clinical trials, record keeping and necropsy procedures. These guidelines should assist both investigators and registration authorities involved in the evaluation of anthelmintics to employ comparable and standard procedures and will have the added benefit of minimising the numbers of animals needed for such tests.

Animal Husbandry↗
PubMed1994

In vivo effect of sublethal concentrations of albendazole metabolites on the structure of the reproductive organs of Dictyocaulus viviparus.

Dictyocaulus viviparus were harvested from calves treated daily with albendazole at dose-rates sub-lethal to this parasite and from matched untreated calves. Male and female reproductive tracts from the worms were examined by light and transmission electron microscopy. A first description of the testis of this nematode is provided. Cell division in the germinal zone of both male and female worms was arrested by in vivo exposure to albendazole metabolites and the cytoplasmic threads connecting the germinal cells to the rachis disappeared. In male worms from treated calves, the rachis was absent from the growth zone and severe ultrastructural damage of spermatogonia, spermatocytes and spermatozoa was apparent. In female worms, the rachis remained intact in the growth zone, obvious abnormalities being confined to the germinal zone, where the cytoplasm of the oogonia was disrupted and few nuclei seen, and to the uteri and ovijector which contained only undifferentiated ova. The detrimental effects of albendazole metabolites on male and female worms were quickly reversed after withdrawal of medication.

Albendazole↗
PubMed1993

Efficacy of fenbendazole and piperazine against developing stages of toxocara and toxascaris in dogs.

In a series of controlled trials involving 59 naturally infected greyhounds, fenbendazole at a dose rate of 50 mg/kg/day for three consecutive days reduced the overall numbers of third and fourth stage Toxocara canis by 94.0 per cent and third stage, fourth stage and immature adult stages of Toxascaris leonina by 92.4 per cent. In contrast, piperazine at 100 mg/kg had little or no useful effect against the larval stages of T canis and T leonina and variable efficacy against immature adult T leonina. Fenbendazole was also 100 per cent effective against immature Trichuris vulpis. In a separate controlled experiment, puppies in three litters exposed to reinfection with T canis were treated with fenbendazole at two weeks old and again only after their mean faecal egg counts exceeded 200 epg. Between one and three doses were required to suppress the output of eggs during the puppies' first 12 weeks of life.

Animals↗
PubMed1993

Gastrin and gastrin-related responses to infection with Ostertagia ostertagi in the calf.

The effects of a single challenge with 60,000 infective Ostertagia ostertagi larvae on blood and gastrointestinal mucosal gastrin concentrations, gastrin-producing G-cell numbers in the pyloric mucosa and growth of different parts of the gut were investigated in 16, two-and-a-half-month-old calves. Infected calves exhibited a rise in abomasal pH which was accompanied by a 145 per cent increase in wet weight of the fundic mucosa (P < 0.05) and a significant rise in blood total gastrin concentrations (P < 0.01). Circulating little gastrin (G-17) was unaffected. Pyloric mucosal total gastrin concentrations remained unaltered in the infected calves until day 28 when levels fell to 36.9 per cent of control group values (P < 0.01). Pyloric mucosal G-cell numbers declined during the experiment in the infected group. It is suggested that release of previously stored tissue gastrin and not a change in G-cell numbers contributes to the hypergastrinaemia associated with ostertagia infection in the calf.

Animals↗
PubMed1993

How much wrapping do babies need at night?

In a longitudinal, population based study, overnight temperature recordings were made in the bedrooms of 152 babies aged 3-18 weeks and the insulation provided by their bedclothing was assessed. Outdoor temperatures for the study nights were also available. Parents applied more insulation on colder nights with lower bedroom temperatures than on warmer nights (mean 8.5 tog at 15 degrees C minimum bedroom temperature falling to 4.0 tog at 25 degrees C). For a particular temperature they also applied 2 tog more insulation in winter than in summer. The amounts of bedclothing used in the home were compared with insulation levels predicted to achieve thermo-neutrality over a similar range of environmental temperature from heat balance studies in young infants. They corresponded closely. The average amount of bedclothing chosen for babies in Avon allows them to remain in thermoneutral conditions throughout the night. These values are proposed as broad guidelines for the thermal care of young babies at night.

Bedding and Linens↗
PubMed1992

Prevalence of benzimidazole-resistance in equine cyathostome populations in south east England.

In order to study the prevalence of benzimidazole-resistance in equine cyathostomes, 30 stables in south east England were selected according to strict criteria but with minimum bias to provide three matched groups of 100 horses. One group was treated with fenbendazole, one with pyrantel embonate and the third was left untreated. The overall efficacies of fenbendazole and pyrantel embonate, as judged by the faecal egg-count reduction test, were 56.3 and 95.8 per cent, respectively. The numbers of horses at individual stables were too small to draw conclusions at each stable, but whereas efficacies greater than 85 per cent were recorded for pyrantel at 26 of 27 stables, the corresponding figure for fenbendazole was five of 27. Cyathostomes accounted for more than 90 per cent of the larvae cultured from faeces before and after treatment. Trichostrongylus axei was detected on 20 sites, but Strongylus species were present on only five. In the area of the survey, benzimidazole-resistance was very widespread in stables which used benzimidazole anthelmintics regularly and had more than nine horses per stable, but the benzimidazole-resistant cyathostome strains were adequately controlled with the non-benzimidazole anthelmintic pyrantel embonate.

Animals↗
PubMed1991

The relationship between appetite and plasma non-esterified fatty acid levels in housed calves.

Non-esterified fatty acid (NEFA) levels in housed, 3-month-old calves were monitored in two experiments designed to establish (i) the effect of diet and time of sampling in relation to feeding on blood levels; and (ii) the relationship between appetite and plasma NEFA in animals on chopped hay. In the first experiment, a significant drop in NEFA levels was recorded after feeding. Furthermore, the NEFA levels of calves maintained on concentrate were significantly lower than those on hay throughout the post-feeding period. In the second study, a significant negative correlation was established between NEFA levels and intake of chopped hay in (i) ad-lib-fed calves infected with the abomasal nematode Ostertagia ostertagi; (ii) worm-free animals pair-fed with those in group (i); and (iii) ad-lib-fed worm-free calves. Regression analysis of raw and transformed data from all three groups combined also yielded significant correlations. It is suggested that the measurement of blood NEFA may be a useful indirect indicator of feed intake in conditioned housed calves offered hay diets.

Animal Feed↗
PubMed1991

Blood gastrin and pepsinogen responses of native village goats in Malaysia to infection with Haemonchus contortus.

Blood gastrin and pepsinogen responses of native village goats in Malaysia to a single dose of 10,500 infective Haemonchus contortus larvae were investigated. Both blood values were significantly elevated within a week of infection and exhibited a highly significant correlation during the study. The magnitude of the blood gastrin response was, however, significantly greater than that of pepsinogen during the period that both blood values were elevated. It is suggested that blood gastrin assay may be of particular value in the diagnosis of chronic haemonchosis in animals harbouring relatively light worm burdens.

Animals↗
PubMed1990

Studies on Ostertagia spp. from Greenlandic sheep: arrested development and worm length.

Studies were conducted to investigate earlier observations that lambs slaughtered in Greenland in late September/early October have relatively few arrested larvae in the abomasal mucosa and that the adult Ostertagia from such lambs are abnormally large. Post mortem examination of naturally infected ewes in mid-winter demonstrated that a significant proportion of their Ostertagia population was hypobiotic at this time of year, while an experimental study showed that considerable numbers of larvae of Greenlandic origin became arrested following cold conditioning for 10 weeks. A comparison of adult Ostertagia of Greenlandic and Britain origins from lambs experimentally infected with larvae cultured under identical conditions demonstrated that the "giant" size of the arctic worms was attributed mainly to environmental rather than genetic influences.

Abomasum↗
PubMed1990

Epidemiology of sheep nematodes in sub-arctic Greenland: sources of infection on rangeland grazing.

Sources of nematode infection on the rangelands of a southern Greenlandic sheep farm were investigated as a part of a study of the epidemiology of Ostertagia and Nematodirus infections in a sub-arctic climate. Herbage larval counts were performed on samples collected from selected localities on the rangeland and post mortem worm-counts made on tracer lambs that had grazed these areas for the latter part of the summer season. Relatively high concentrations of larvae were found in good quality native grasses at sea-level and in grasses growing beneath canopies of willow-shrub at higher altitudes. In general, however, the infectivity of the vegetation was very low and the pick-up of infection by the tracer lambs was correspondingly small.

Animals↗