To test the hypothesis that atrial natriuretic peptide (ANP) concentration in the newborn is negatively related to plasma renin concentration (PRC), as it is in the adult, we measured the concentration of both substances in the same plasma sample. We studied 24 well term newborns and 20 samples of umbilical venous blood from normal deliveries. Both ANP and PRC are elevated in newborn plasma, but not in umbilical venous plasma. ANP levels on the second day of life are greater than either day 1 or day 3. Linear regression of ANP and PRC demonstrates a highly significant negative correlation [r = -0.65, p less than 0.001], which suggests that the suppression of the renin-angiotensin system by ANP seen in the adult may be intact in the newborn. ANP may act to blunt the effects of the augmented renin-angiotensin system of the newborn and promote normal neonatal diuresis.

Atrial Natriuretic Factor↗

PubMed1990

Insulin resistance and blood pressure in young black men.

Insulin resistance, independent of obesity or non-insulin-dependent diabetes mellitus, has been demonstrated to be associated with high blood pressure. To determine if insulin resistance could be an antecedent to hypertension in a high-risk population, we studied normotensive (112 +/- 12/70 +/- 10 mm Hg) and borderline hypertensive (135 +/- 8/85 +/- 5 mm Hg) lean young black men (22-26 years old) with the euglycemic hyperinsulinemic clamp technique. All subjects had clinically normal oral glucose tolerance. Body mass index and percent adipose mass were the same in both groups. Fasting plasma insulin concentration was significantly higher in the borderline hypertensive group (p less than 0.01). Insulin-directed exogenous glucose metabolism at the same degree of steady-state hyperinsulinemia was significantly lower in the borderline hypertensive group (5.98 +/- 2.22 versus 8.22 +/- 1.96 mg/kg/min; p less than 0.01). For the total population, a significant inverse correlation existed between the glucose infusion rate and systolic blood pressure (p less than 0.01). These data indicate that there is a relation between insulin-mediated glucose uptake and blood pressure. Furthermore, in this high-risk population insulin resistance may precede the onset of established essential hypertension.

Adult↗

PubMed1986

Animal rights: some guideposts for the veterinarian.

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Animal Welfare↗

PubMed1986

Cytochalasin D alters the rate of synthesis of some HEp-2 cytoskeletal proteins. Examination by two-dimensional gel electrophoresis.

The most abundant proteins of HEp-2 cells were resolved by two-dimensional gel electrophoresis. The protein spots corresponding to several cytoskeletal proteins (vimentin, alpha-tubulin, beta-tubulin, alpha-actinin, tropomyosins, and cytokeratins) were identified by comigration with protein markers or by immunological techniques. After treatment of HEp-2 cells with 0.2 microM or 2.0 microM cytochalasin D for 20 h, radioautograms of two-dimensional gel patterns of lysates from cells pulse-labeled with [35S]methionine indicated that the drug altered the rate of synthesis of some proteins. The relative rate of synthesis of the identified cytoskeletal proteins was measured. Synthesis of alpha-actinin, the higher-molecular-mass pair of tropomyosins and actin were similarly increased with cytochalasin D treatment, suggesting coordinate induction. Vimentin and tubulin synthesis was depressed. One cytokeratin exhibited an increase in synthesis comparable to actin, another was increased to a lesser extent and one was decreased.

Actinin↗

PubMed1986

Ureteral occlusion decreases phospholipid and cholesterol of renal tubular membranes.

Unilateral ureteral obstruction of 24 h duration in the dog results in a 20% decrease in the amount of total phospholipids present in basolateral membranes of renal tubular cells obtained from the experimental kidney as compared with the amount of phospholipid in basolateral membranes prepared from the contralateral kidney of the same dogs or from the kidneys of normal sham-operated dogs. There was also a decrease in the content of cholesterol and cholesterol esters of the basolateral membranes from the experimental kidney. By contrast, no significant change in lipid content was observed in brush border membranes obtained from the experimental kidney of dogs with unilateral ureteral obstruction. The decrease in phospholipid content of basolateral membranes was accompanied by a 40% fall in the content of phosphatidylcholine and a 12% fall in sphingomyelin. There was a small (12%) but significant increase in the content of phosphatidylethanolamine in basolateral membranes. The mechanisms responsible for the selective decrease in phospholipid content of basolateral membranes remain to be established. It is postulated that changes in solute transport and altered response to hormones observed in the postobstructed kidney of animals with unilateral ureteral obstruction may be explained, at least in part, by changes in the lipid composition of basolateral membranes.

Animals↗

PubMed1986

Stimulation of actin synthesis by cytochalasin D is specific for the isoactins normally expressed in muscle or non-muscle cells.

Treatment of human muscle myotube cultures with 2 microM-cytochalasin D (CD) for 6 h stimulated synthesis of both the (muscle-specific) alpha-actin and the (non-muscle) beta and gamma-actins usually expressed by these cells. In non-muscle (HEp-2) cell cultures, CD enhanced synthesis of beta and gamma-actin, but did not induce synthesis of alpha-actin, which is not normally present in these cells. Thus, synthesis of both muscle and non-muscle actins can be increased by CD, but enhancement of actin synthesis results from increases in the isoactins usually present, rather than induction of new isotypes. Comparison of CD-treated (fused) myotube cultures with (unfused) myoblast cultures indicated that beta and gamma-actin synthesis was similarly enhanced in both cultures, but that alpha-actin synthesis was stimulated to a greater extent in the myoblast cultures. Desmin synthesis was also stimulated in the myoblasts but not the myotubes, suggesting that the effect of CD on synthesis of these developmentally regulated cytoskeletal proteins (alpha-actin, desmin) might be modulated by fusion or the state of differentiation of the muscle cell.

Actins↗

PubMed1985

Evidence for regulation of actin synthesis in cytochalasin D-treated HEp-2 cells.

In HEp-2 cells treated with 0.2 or 2.0 microM cytochalasin D (CD), the relative rate of actin synthesis increased for about 12 h and then reached a plateau; this increase was suppressed by actinomycin D (AD). When CD was washed from cells which had been treated for 20 h, the elevated rate of actin synthesis declined to the control value within ca 4 h, as the actin-containing cytoskeletal components rearranged by CD recovered their normal morphology. Subsequently, actin synthesis was depressed below control values for a prolonged period; during recovery from 2 h treatment with CD, this depression was of much shorter duration. Re-addition of CD to cells after a 3 h recovery period again induced the cytoskeletal alterations characteristic of CD treatment but did not reverse the prior decline in the rate of actin synthesis. In HEp-2 cells treated with cycloheximide during exposure to CD for 20 h, the relative rate of actin synthesis measured after removal of cycloheximide was twofold higher than with CD alone and such cells exhibited a twofold slower decline in the rate of actin synthesis during recovery from CD in the continued presence of cycloheximide. These effects of cycloheximide, which resemble observations on "super-induction", suggest that actin synthesis in CD-treated and recovering HEp-2 cells may be regulated by a repressor protein. The possibility that the proposed repressor protein is actin and that actin may thus be a feedback inhibitor of its own synthesis is discussed.

Actins↗

PubMed1985

Increased actin content in cytochalasin D-treated cells is not caused by a selective decrease in actin degradation.

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Actins↗

PubMed1985

Cytochalasin D-induced increase in actin synthesis and content in a variety of cell types.

Treatment of a variety of mesenchymal cells (normal and transformed rat fibroblasts, bovine aortic endothelial cells, rabbit smooth muscle cells), exhibiting different cytoskeletal organizations and derived from several species, with doses of cytochalasin D (CD, 2-6 microM for 20 h) sufficient to induce cytoskeletal rearrangement and altered cellular morphology results in an increase in the relative content and rate of synthesis of actin. These data extend our previous findings for HEp-2 cells to other cell types and provide further evidence for our hypothesis that the CD-induced cytoskeletal reorganization triggers stimulation of actin synthesis and the resulting increase in actin content.

Actins↗

PubMed1985

Ethics and human-companion animal interaction. A plea for a veterinary ethics of the human-companion animal bond.

For both moral and practical reasons, the veterinary profession must begin to nurture a serious veterinary ethics of human-companion animal interaction. Among the central concerns of such a discipline will be the moral value of the veterinary patient: the moral significance of human-animal companionship; the proper response of the practitioner to conflicts of interests between the patient, its owner, and himself; and the proper role of the practitioner in the client's decisions. Approaches that urge moral equality of man and animal or encourage the veterinarian to control the client's decision undervalue the moral status of the animal owner in the human-companion animal bond.

Animals↗

PubMed1985