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Biomedical subjects

W D Roberts

Publications and source records attributed to W D Roberts.

10 recordsLinked to original sources
PubMed1998

Severity and persistence of footrot in Merino sheep experimentally infected with a protease thermostable strain of Dichelobacter nodosus at five sites.

OBJECTIVE: To test the hypothesis that ovine footrot associated with a thermostable protease strain of Dichelobacter nodosus undergoes self cure or is sustained as an annually recurring disease, depending on the environment. DESIGN AND PROCEDURE: Forty Merino sheep from a single blood line were infected with a protease thermostable strain of D nodosus at each of five sites in Western Australia. Footrot lesions and microscopic evidence of D nodosus were recorded every fortnight for 2.5 years, supplemented by laboratory culture. Rainfall, soil and air temperature, pasture quantity and composition and soil types were also recorded. Flocks that apparently self cured were relocated to a more favourable site for footrot in the final spring season. RESULTS: The maximum prevalence of feet with clinical footrot lesions was 80.6, 1.3, 14.4, 3.8 and 88.1% at the five sites. Severe footrot occurred for three consecutive spring seasons at one site that had clay loam soil and at least 3500 kg/ha total pasture dry matter annually. However, the infection was asymptomatic for up to 10 weeks between outbreaks. D nodosus was isolated from flocks for 2.5 years at only two sites, although there was microscopic evidence of the organism at other sites in the final year. A thermolabile variant (strain U6) of D nodosus was isolated from the two sites where footrot persisted. CONCLUSION: Depending on time and location, ovine footrot induced by a protease thermostable strain of D nodosus either self cured or persisted as annual outbreaks interspersed with periods of asymptomatic infection.

Animals↗
PubMed1994

Muscle enzymes in the diagnosis of ovine weaner nutritional myopathy.

The diagnostic performance of plasma tests for muscle enzymes was measured in sheep from flocks affected by clinical and sub-clinical nutritional myopathy. Parallel combinations of tests for creatine kinase (CK), alanine amino transferase (ALT), aspartate amino transferase (AST) and lactate dehydrogenase had higher diagnostic sensitivity than CK alone. The enzymes ALT and AST showed the highest correlation with the degree of muscle damage. A parallel combination of tests for plasma CK and ALT as well as tests for plasma alpha-tocopherol and red cell glutathione peroxidase are recommended for the diagnosis of nutritional myopathy and a decision on the appropriate treatment. The number of false negative results based on a diagnosis from the microscopic examination of single muscles was higher than for the parallel combination of tests. The number of false negatives was highest for the vastus intermedius and lowest for the tensor fascia lata. Diagnosis using a panel of blood tests has the advantages of overcoming problems of inadequate muscle sampling, a larger number of sheep in the flock can be tested and a more rapid diagnosis can be obtained.

Alanine Transaminase↗
PubMed1993

Granulocyte recovery in pediatric marrow transplant recipients treated with ganciclovir for cytomegalovirus infection.

PURPOSE: Cytomegalovirus (CMV) infection remains a major cause of morbidity and mortality after bone marrow transplantation (BMT). Ganciclovir is a guanosine analogue that selectively inhibits CMV DNA polymerase and appears to be a useful agent for BMT patients with CMV pneumonia. One major side effect of ganciclovir is neutropenia, and there may be reluctance to administer ganciclovir to neutropenic patients. However, there is evidence that CMV infection may directly or indirectly cause marrow suppression. In this situation, the potential benefit of ganciclovir may outweigh the risk. PATIENTS AND METHODS: We retrospectively reviewed the charts of 11 consecutive patients receiving ganciclovir for CMV infection posttransplant. A total of 13 courses of ganciclovir were administered. RESULTS: In 10 of 13 cases, the absolute neutrophil count was higher at the completion of ganciclovir therapy than at the start of treatment, including five cases where the absolute neutrophil count was < 500/mm3 at the time ganciclovir was started. In only one of 13 cases was ganciclovir discontinued due to neutropenia. CONCLUSIONS: We conclude that the administration of ganciclovir is not often associated with the development of severe neutropenia in pediatric marrow transplant recipients and that ganciclovir can be safely administered to patients with CMV disease, who are severely neutropenic.

Adolescent↗