Search PubMed⌕ Search

Biomedical subjects

S Jacobs

Publications and source records attributed to S Jacobs.

At least 217 records · Page 12Linked to original sources
PubMed1979

Modulation of binding and bioactivity of insulin by anti-insulin antibody: relation to possible role of receptor self-aggregation in hormone action.

Incubation of physiological concentrations of 125I-labeled insulin with liver membranes in the presence of anti-insulin IgG results in a 7- to 15-fold increase in the specific binding of the hormone. The low-affinity/high-capacity binding sites are replaced by an apparently homogeneous class of high-affinity sites, and the nonlinear Scatchard plots are converted to linear plots without a change in the maximum number of binding sites. Similarly, the binding of insulin to receptors in 3T3 fibroblasts is increased substantially in the presence of anti-insulin antibody, and the biological activity of subactive concentrations of insulin is enhanced by antibody in these cells. However, the affinity of 125I-labeled epidermal growth factors (EGF) in fibroblasts is not affected by anti-EGF IgG. In adipocytes anti-insulin IgG in the same concentration range only inhibits the binding of insulin and suppresses insulin-mediated glucose oxidation. Monovalent Fab' fragments from anti-insulin IgG inhibit the binding of the hormone, indicating that the enhancement of binding in liver membranes and fibroblasts requires the bivalency of the antibody.

Animals↗
PubMed1979

Extracellular space, water, and ion concentration in the hypertrophied rat myocardium.

Extracellular space (ECS), water, and intracellular ion concentration were determined in the normal and hypertrophied rat myocardium. Theoretical measurements of myocardial ECS based on a mathematical model (9.31%) closely approximated the observed results in the normal myocardium (12.8%) and hypertrophied myocardium (11.7%). Observed results confirmed theoretical considerations of no change in ECS with hypertrophy. ECS and water content were higher in the right ventricle than the left ventricle, but intracellular electrolytes remained unchanged. Myocardial hypertrophy did not alter these relationships.

Animals↗
PubMed1978

Antibodies to purified insulin receptor have insulin-like activity.

Antibodies to insulin receptors purified from rat liver membranes do not complete with [125I]insulin for binding to the insulin receptor but do precipitate solubilized receptors labeled with [125I]insulin. These antibodies have the insulin-like activities of enhancing glucose oxidation and inhibiting epinephrine-induced lipolysis in rat adipocytes. Thus, antibody binds to the receptor at a different site from that to which insulin binds, yet the interaction can initiate an effective biological response. These results indicate that the previously studied insulin-binding sites are the physiological macromolecular receptors for insulin.

Acanthosis Nigricans↗
PubMed1978

Peritoneovenous (LeVeen) shunt. Control of renin-aldosterone system in cirrhotic ascites.

Because of the unusual clinical course of a patient with hepatic cirrhosis, refractory ascites, and hepatorenal syndrome, we were able to examine the complex interrelationships between massive ascites, renin-aldosterone activity, and renal and hepatic function before and after placement of a peritoneojugular vein (LeVeen) shunt. Measurements indicated that when the shunt was functioning, renin-aldosterone production was suppressed, the hepatorenal syndrome was reversed, and ascites remitted. These data suggest that hyperreninemia, hyperaldosteronism, and functional renal abnormalities of this disorder are potentially reversible and arise primarily from the imbalance between formation and drainage of hepatosplanchnic lymph rather than from hepatocellular dysfunction, lowered plasma oncotic pressure, or portal hypertension.

Adult↗
PubMed1978

Fluorescent labeling of hormone receptors in viable cells: preparation and properties of highly fluorescent derivatives of epidermal growth factor and insulin.

Highly fluorescent analogs of insulin and epidermal growth factor were prepared by the covalent attachment of these peptides to alpha-lactalbumin molecules that were highly substituted (i.e., seven to one) with rhodamine molecules. The alpha-lactalbumin was specifically linked to the lysine residue of insulin or to the alpha-amino group of epidermal growth factor. The insulin derivative retained 1.15% of its potency in stimulating glucose oxidation in fat cells but retained about 8.3% of its binding affinity toward receptors. The epidermal growth factor derivative was completely active in binding to fibroblast receptors and 40% as potent as the native hormone in stimulating DNA synthesis. These highly fluorescent derivatives were suitable for the specific visual labeling of receptor sites in viable cells and for measuring the lateral mobilities of the receptor-hormone complexes by fluorescent photobleaching recovery techniques. By these methods it was shown that the hormone-receptor complexes can move laterally in the plane of the plasma membrane with a diffusion coefficient of (3-5) X 10(-10) cm2/sec.

Adipose Tissue↗
PubMed1978

Studies on vaginal malodor. I. Study in humans.

Forty-two percent of collagen sponges tested as an intravaginal barrier contraceptive method developed malodor when retained for 5 days. Only 4% developed odor when the sponge was removed within 24 hours after intercourse, rinsed, and reinserted. While sexually active volunteers found odor in 37% of the sponges, odor formed only in 4% of the sponges worn by sexually inactive users. No difference in the rate of odor formation was found when neutral pH (7.0) and acid pH (3.4) collagen sponges were tested, although we believe that a pH 3.4 is too acid and promotes odor formation. The optimal pH of the sponge should be 4.5 to 5.5. Malodor was efficiently extracted from sponges by washing in acid milieu of tap water and vinegar or 0.1 M acetate buffer, pH 4.0. Alkali extraction procedures were ineffective, and lukewarm water was slightly less effective than acid extraction of odor. At the time of malodor development, the high content of polyamines (putrescine, spermine, spermidine) in the ejaculate decreased to undetectable values. We conclude that the ejaculate is the major source of malodor formation in intravaginally worn collagen sponges. Removal, rinsing optimally in vinegar solution, and reinsertion within 24 hours after intercourse reduces the chance of malodor formation.

Adult↗
PubMed1977

Anteromedian external urethral sphincterotomy: technique, rationale and complications.

Experiences are presented with bilateral (3 and 9 o'clock incisions) and anteromedian (12 o'clock incision) external urethral sphincterotomy in 84 patients with neuropathic vesicourethral dysfunctions. Hemorrhage and loss of reflexogenic erections have been notably absent in 31 patients who underwent anteromedian sphincterotomy. The rationale is discussed for the preference of anteromedian over bilateral sphincterotomy based on postoperative complications. The postoperative, radiologically aided cystosphincterometric and electromyographic studies during micturition indicated the adequacy of the surgical procedures, satisfying the urodynamic criteria, although dyssynergic myolectric activity of the periurethral striated muscle continued to exist.

Electromyography↗
PubMed1977

The effect of jejunoileal bypass on the pharmacokinetics of digoxin in man.

Seven subjects who underwent jejunoileal bypass surgery for massive obesity participated in a study to examine the relative bioavailability of digoxin before and one to two months after surgery. They were given a loading dose of 1 mg digoxin in divided oral doses followed by oral maintenance doses of 0.5 mg daily. There were no significant differences in the area under the serum concentration time curve, steady state serum levels or 24 hour steady state excretion of digoxin before and after surgery. We conclude that the bioavailability of digoxin from the Lanoxin tablets employed is not impaired in these patients, although urinary d-xylose and 24 hour fecal fat excretion indicated moderate to severe malabsorption after surgery.

Digoxin↗
PubMed1977

Neurophysiological correlates of acupuncture: limbic and thalamic responses to analgesic studies in non-human primates.

Single unit activity from chronically implanted squirrel monkeys was analyzed to evaluate the effect of acupuncture stimulation on limbic and thalamic structures associated with pain. Extracellular recordings and computer-generated interspike interval histograms (ISIH) were obtained from n. parafasicularis and n. ventralis posteromedialis of the thalamus and the laternal septum, basal amygdala and anterior cigulate cortex. Thalamic activity remained unchanged while limibc units demonstrated statistically significant alterations in both cell firing rate and the ISIH in response to acupuncture stimulation. Although pain thresholds in response to tooth pulp stimulation were increased by morphine (37-51% +/- 2.1), acupuncture proved totally ineffective. This may be interpreted as a selective response to acupuncture in CNS structures primarily concerned with the affective component of pain.

Action Potentials↗