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Biomedical subjects

S D Morris

Publications and source records attributed to S D Morris.

27 records · Page 2Linked to original sources
PubMed1996

Specific induction of the 70-kD heat stress proteins by the tyrosine kinase inhibitor herbimycin-A protects rat neonatal cardiomyocytes. A new pharmacological route to stress protein expression?

Heat shock protein (hsp) induction by stressful stimuli such as heat and ischemia is known to protect cardiac cells from severe stress. The ability to induce hsp's in the heart directly by "nonstressful" means would potentially have important clinical implications. In noncardiac cells, the tyrosine kinase inhibitor herbimycin-A has been shown to induce the 72-kD hsp. We therefore examined whether herbimycin-A and another tyrosine kinase inhibitor, genistein, could induce 70-kD hsp's in primary cultures of rat neonatal cardiomyocytes, and whether these treatments protect against severe stress. Primary cardiomyocytes were incubated with herbimycin-A or genistein. hsp induction was measured 16-20 h later by Western blotting. Cell survival after subsequent lethal heat stress or simulated ischemia was assessed using trypan blue exclusion and released lactate dehydrogenase activity. Our results indicate that, in cardiac cells, herbimycin-A induces 70-kD hsp's but not hsp90, -60, -25, or glucose-regulated protein 78, whereas genistein has no effect on hsp's. Moreover, hsp induction correlated with the ability of herbimycin-A to protect cells against severe stress, whereas genistein has no protective effects. This suggests that herbimycin-A may induce 70-kD hsp's via a tyrosine kinase-independent mechanism. These results indicate the possibility of a pharmacological approach to HSP70 induction and cardiac protection, which may ultimately be of clinical relevance.

Animals↗
PubMed1996

Serological survey to determine the prevalence of bovine leukaemia virus antibodies in dairy cattle on selected farms in the Gauteng and Mpumalanga provinces.

Cattle from a farm where enzootic bovine leukosis had been diagnosed were tested to determine the prevalence of bovine leukaemia virus antibodies. Farmers who had bought cattle from this farm were identified and their herds also tested. Of 381 adult dairy cattle tested, 14 animals reacted positively (3.67%). Cattle (n = 81) from 3 selected herds, not associated with the affected farm were also bled and 7 animals reacted positively (8.64%).

Animals↗
PubMed1996

The possible role of two common three-host ticks, Rhipicephalus appendiculatus and Amblyomma hebraeum, in the transmission of bovine leukosis virus.

The possible role of Rhipicephalus appendiculatus and Amblyomma hebraeum in the mechanical and transstadial transmission of bovine leukosis virus (BLV) was investigated. BLV-free laboratory strains of R. appendiculatus and A. hebraeum nymphal ticks (n = 400) were fed on a BLV-infected and a negative control bovine. At various intervals after engorgement the ticks were homogenised and injected subcutaneously into BLV-negative sheep. Adult R. appendiculatus and A. hebraeum, which had fed as nymphs on the BLV-infected bovine, were then allowed to feed on BLV-negative sheep. A control sheep was also injected intravenously with blood from the infected bovine. Only the control sheep that received blood from the BLV-positive bovine seroconverted 9 months later. All the other surviving sheep remained serologically negative during the 13 months observation period. It is suggested that the nymphal stages of these ticks probably do not play a role in the transstadial transmission of BLV in southern Africa. The significance of these results is discussed.

Animals↗
PubMed1995

Aortic thromboembolism associated with traumatic reticuloperitonitis in a downer cow.

A large thrombus was found at the ileal bifurcation on post mortem examination of a 6-year-old Jersey cow which presented clinically with a history of acute onset recumbency, hind limb paresis and skin necrosis over the sacral area. Other significant findings on post mortem were traumatic reticuloperitonitis accompanied by mural thrombosis of the left ventricle associated with a purulent sinus tract through the ventricular wall, fibrous adhesions between the pericardium, diaphragm and liver, and multiple infarcts in both kidneys.

Animals↗
PubMed1993

A serological survey of bovine brucellosis in the Molopo District of Bophuthatswana.

A serological investigation was carried out in the Molopo district of Bophuthatswana to determine the prevalence of brucellosis titre in heifers and cows (n = 9,675) over 24 months of age, which were grazing on communal tribal and privately owned land. The Rose Bengal, micro serum agglutination and complement fixation (CFT) tests were used. Two hundred and two (2.1%) animals tested positive with a CFT titre of 30 (IU ml-1) or higher. Factors that could have contributed to the relatively low prevalence are discussed.

Animals↗
PubMed1981

A comparison of different rigid contact lenses: edge thicknesses and contours.

The edge thickness and contour of rigid lenses is an important factor in lens comfort and acceptance. In this study the edges of two CAB lenses, a PMMA-silicone combination lens, a pure silicone lens had standard PMMA lenses are evaluated by molding the lenses. Considerable variation in thickness and contour of the peripheral portion of the lenses were found.

Contact Lenses↗