Sex differences in the subcellular distribution of angiotensin type 1 receptors and NADPH oxidase subunits in the dendrites of C1 neurons in the rat rostral ventrolateral medulla.

The rostral ventrolateral medulla (RVLM), a region critical for the tonic and reflex control of arterial pressure, contains a group of adrenergic (C1) neurons that project to the spinal cord and directly modulate pre-ganglionic sympathetic neurons. Epidemiological data suggest that there are gender differences in the regulation of blood pressure. One factor that could be involved is angiotensin II signaling and the associated production of reactive oxygen species (ROS) by NADPH oxidase, which is emerging as an important molecular substrate for central autonomic regulation and dysregulation. In this study dual electron microscopic immunolabeling was used to examine the subcellular distribution of the angiotensin type 1 (AT(1)) receptor and two NADPH oxidase subunits (p47 and p22) in C1 dendritic processes, in tissue from male, proestrus (high estrogen) and diestrus (low estrogen) female rats. Female dendrites displayed significantly more AT(1) labeling and significantly less p47 labeling than males. While elevations in AT(1) labeling primarily resulted from higher levels of receptor on the plasma membrane, p47 labeling was reduced both on the plasma membrane and in the cytoplasm. Across the estrous cycle, proestrus females displayed significantly higher levels of AT(1) labeling than diestrus females, which resulted exclusively from plasma membrane density differences. In contrast, p47 labeling did not change across the estrous cycle, indicating that ROS production might reflect AT(1) receptor membrane density. No significant differences in p22 labeling were observed. These findings demonstrate that both sex and hormonal levels can selectively affect the expression and subcellular distribution of components of the angiotensin II signaling pathway within C1 RVLM neurons. Such effects could reflect differences in the capacity for ROS production, potentially influencing short term excitability and long term gene expression in a cell group which is critically involved in blood pressure regulation, potentially contributing to gender differences in the risk of cardiovascular disease.

Intra-abdominal versus intramuscular application of two ampicillin preparations in cows.

Plasma ampicillin concentrations were determined in a cross-over trial involving five cows after single intramuscular or intra-abdominal administration of sodium ampicillin (10 mg/kg) and ampicillin anhydrate (40 mg/kg). After injection of sodium-ampicillin, high plasma concentrations were reached within 10 min; Cmax following intramuscular injection was 9.1 micrograms/ml and after intra-abdominal injection 7.5 micrograms/ml. Urine concentrations of ampicillin were low after 24 h (1-1.5 micrograms/ml). No significant changes in blood leucocyte numbers, plasma zinc, iron or fibrinogen levels occurred. After injection of ampicillin anhydrate 1 h elapsed before maximum plasma levels were obtained; Cmax was 5.4 micrograms/ml after intramuscular and 6.7 micrograms/ml after intra-abdominal administration. Urine concentrations were very high (238-303 micrograms/ml) after 24 h and stayed above 1 microgram/ml for 6 days. After administration of ampicillin anhydrate a significant increase in blood neutrophils (P less than 0.01) and a significant increase in plasma fibrinogen was measured after intramuscular and intra-abdominal injection (P less than 0.05). A significant decrease in plasma zinc concentration after intra-abdominal injection occurred (P less than 0.05). In abdominal surgery in cows in which contamination cannot be prevented, and practical objections inhibit preoperative administration, intramuscular or intra-abdominal administration during surgery of sodium ampicillin seems justified. Ampicillin anhydrate should not be used intra-abdominally.

[Practical application of recombinant bovine somatotropin: sequelae for man, animal and animal husbandry]. / Praktische toepassing van recombinant bovine somatotropine: gevolgen voor mens, dier en bedrijfsvoering.

Recombinant Bovine Somtatotropin (r-BST) may be produced commercially in the forseeable future. On the basis of a study of the literature, it may be assumed in all likelihood that administration of r-BST to dairy cows will not have a negative effect on public health. However additional research on potential biological activity of recombinant-BST or its fragments and of somatomedins after oral administration, is advisable. Negative effects on the health, fertility and life-span of animals were not observed so far under experimental conditions but any reference to field situations is absent in the literature. Treatment with r-BST should not be initiated prior to within eighty days after parturition. Administration of r-BST also requires proper management in terms of ration formulation and feeding to ensure maintenance of health and production of dairy cattle. The use of r-BST will result in a less accurate estimation of the breeding potential of selected cows, resulting in a reduction of the genetic improvement of milk production. Increased economic benefits should be obtained on farms having high stocking rates (2.35 dairy cows/ha) compared with those having low stocking rates (1.90), varying with the price of r-BST. It is anticipated that the use of r-BST will have little effect on the reduction of the number of dairy cattle and dairy farms up to 1995.

[Somatotropin: structure, (bio)synthesis and species specificity]. / Somatotropine: structuur, (bio)synthese en diersoortspecificiteit.

The literature on biosynthesis and species specificity of bovine somatotropin (BST) is reviewed. Somatotropin is a hypophyseal hormone consisting of 190 amino acids, having, among other things, a stimulating effect on milk synthesis. Recombinant DNA-techniques have been used since 1982 to produce BST and this has paved the way for large-scale use of r-BST. It is assumed that the somatotropin molecule has several active sites responsible for a multitude of biological effects following interaction with specific receptors. Somatotropin of different animals have a varying amino acid composition. Sixty-five per cent of human and bovine somatotropins are homologues in amino acid sequence. BST is found to be virtually inactive when used therapeutically in human individuals.