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Biomedical subjects

J Silver

Publications and source records attributed to J Silver.

At least 361 records · Page 20Linked to original sources
PubMed1983

Systolic blood pressure and long-term practice of the Transcendental Meditation and TM-Sidhi program: effects of TM on systolic blood pressure.

Systolic blood pressure was measured in 112 subjects practicing the Transcendental Meditation (TM) and TM-Sidhi programs. The subjects were between the ages of 35 and 64 years. A significant difference was found between the systolic blood pressures of subjects (matched for sex, race, and general educational background) practicing the TM and TM-Sidhi programs and norms for the general population. This difference was independent of diet and exercise patterns but related to length of time meditating. A significant difference was also found between short-term (under 5 years) and long-term (over 5 years) participants of the TM program, covarying for age. No previous reports exist concerning the long-term effects of the TM program on blood pressure. Despite methodological problems associated with cross sectional data, the findings suggest the beneficial effects of the long-term practice of the TM and TM-Sidhi programs on systolic blood pressure. Even if self-selection plays a role, the characteristics of an easily identifiable group already showing traits beneficial to the general population deserves further study.

Adult↗
PubMed1983

Hypervolemia and plasma vasopressin response during water immersion in men.

To investigate changes in plasma volume (PV) and osmolality as stimuli for plasma vasopressin (PVP) suppression and diuresis, seven normal healthy men (22-48 yr) were immersed to the neck for 4 h in a sitting position in tap water (34.5 degrees C) after overnight food and fluid restriction. Mean +/- SE urine volume was 823 +/- 123 ml/4 h; fluid intake was 400 ml/4 h, and mean negative water balance was 944 ml/4 h. Urinary sodium excretion increased from 0.77 to 1.25 mosmol/min (P less than 0.05) and UNaV from 0.14 to 0.37 meq/min (P less than 0.05). During immersion, PV (T-1824) increased by 8.8% (P less than 0.05) during the first 30 min and declined linearly thereafter. Mean +/- SD serum osmolality (294 +/- 1.2 mosmol/kg H2O) and sodium (143.2 +/- 0.4 meq/l) were constant throughout immersion; PVP (2.3 +/- 0.5 pg/ml) and plasma renin activity [0.3 +/- 0.2 ng ANG I/(ml X h]) were not significantly changed. Thus, the composition of the fluid entering the vascular space maintained constant serum osmolality and PVP throughout immersion. These findings do not support the hypothesis that acute expansion of central volume and PV cause suppression of PVP. The results suggest a mechanism other than or in addition to PVP suppression as a contributory cause of the immersion diuresis.

Adult↗
PubMed1983

Multiple myeloma presenting as dense deposit disease. Light chain nephropathy.

A 45-year-old male was admitted to the hospital because of polyuria and polydipsia. After admission, proteinuria and hematuria were found. The kidney function deteriorated and necessitated the initiation of chronic hemodialysis. Examination of the bone marrow revealed multiple myeloma and kappa light chains were found in the urine. The kidney biopsy showed membranoproliferative glomerulonephritis with dense deposits in the glomerular basement membrane.

Basement Membrane↗
PubMed1983

Antigen-presenting capabilities of human monocytes correlates with their expression of HLA-DS, an Ia determinant distinct from HLA-DR.

Utilizing a monoclonal antibody (Mac-120) specific for 40 to 60% of peripheral blood adherent mononuclear cells (M phi), we were able to separate M phi into two populations based on their reactivity with the antibody. Both populations, Mac-120+ and Mac-120- cells, were then compared for a) their ability to present antigen to T cells, b) their display of HLA-DR determinants, c) their ability to stimulate in an autologous and allogeneic mixed lymphocyte reaction, and d) their display of an Ia molecule, HLA-DS, which is distinct from HLA-DR and which is homologous with murine I-A. Our findings indicate that a) only Mac-120+ cells can present antigen, b) Mac-120+ and Mac-120- cell populations are equivalent in terms of the number of HLA-DR+ cells and in the mean density of HLA-DR determinants per cell, c) although Mac-120+ and Mac-120- cells are equivalent in their ability to serve as stimulators in an allogeneic mixed lymphocyte reaction, Mac-120+ cells are better stimulators in an autologous mixed lymphocyte reaction, and d) only Mac-120+ cells display HLA-DS. These studies demonstrate that peripheral adherent mononuclear cells exhibit heterogeneity with regard to their display of Ia antigens. Furthermore, they provide functional data to support the existence of a human Ia determinant, HLA-DS, which is distinct from HLA-DR and which is important in antigen presentation and stimulation in the autologous mixed lymphocyte reaction.

Amino Acid Sequence↗
PubMed1983

Social aspects of visual disability.

Over 40 million people are estimated to be limited in the work they can do by a visual disability, most of them in the Third World. Much preventable blindness goes unchecked and even reversible blindness is untreated in countries where aphakic spectacles may cost the equivalent of a year's earnings. In the United Kingdom and other advanced countries the problems are very different. Visual disability is 100 times more likely to occur in a person over 75 than in a child. The disabled carry heavy penalties, social, financial and psychological. Society, when it is aware, tends to "look after" the disabled person, rather than provide him with the means to look after himself, but services are inadequate to meet demands.

Adolescent↗
PubMed1982

Effects of ovariectomy on the binding of [125I]-alpha bungarotoxin (2.2 and 3.3) to the suprachiasmatic nucleus of the hypothalamus: an in vivo autoradiographic analysis.

alpha-Bungarotoxin (alpha-BTX) has been used to label receptor binding sites on neural membranes. alpha-BTX fractions 2.2 and 3.3 were purified from Bungarus multicinctus by the method of Ravdin and Berg (1979) and we iodinated. There was no difference between these two fractions in their binding affinity or specificity of binding with hypothalamic synaptosomes. [125I] alpha-BTX 2.2S, 3.3 and commercially obtained [125I] alpha-BTX were injected into the third ventricle of ovariectomized female rats (n = 22), normally cycling rats (n = 12) or normal male rats (n = 4) and autoradiographic examination performed. Saline injected hypothalami (n = 4) or hypothalamus. Examination of serial sections from animals injected with each [125I] alpha-BTX showed that the supraoptic, periventricular, arcuate, premamillary and mamillary nuclei were consistently labeled. While the suprachiasmatic nucleus (SCN) in the intact females and males both showed high densities of alpha-BTX binding, the SCN in ovariectomized females showed little or no alpha-BTX binding. Thus, the labeling of the SCN in females without ovaries and ovarian hormones was markedly different from that of the intact males and females. Labeling patterns in castrate and intact animals may contribute to our understanding of gonadal steroid regulation of hypothalamic function.

Animals↗
PubMed1982

Axonal guidance during development of the great cerebral commissures: descriptive and experimental studies, in vivo, on the role of preformed glial pathways.

Do structures exist within the embryonic central nervous system that guide axons across the midline during development of the great cerebral commissures (corpus callosum, anterior commissure)? With the use of serial section and reconstructive computer graphic techniques we have found that during normal ontogeny of the mouse forebrain and before the arrival of the pioneer fibers of the corpus callosum at the midline, a population of primitive glial cells migrates medially (through the fused walls of the dorsal septum) from the ependymal zones of each hemisphere. At the midline, and well rostral to the lamina terminalis, these cells unite to form a bridgelike structure or "sling" suspended below the longitudinal cerebral fissure. The first callosal axons grow along the surface of this cellular bridge as they travel toward the contralateral side of the brain. The "sling" disappears neonatally. The fibers of the anterior commissure grow within the lamina terminalis along a different type of preformed glial structure. Movement of these axons occurs through an aligned system of glial processes separated by wide extracellular spaces. Do these transient glial tissues actually provide guidance cues to the commissural axons? Analyses of three situations in which the glial "sling" is genetically or surgically impaired or nonexistent indicate that this structure does, indeed, play an essential role in the development of the corpus callosum. We have analyzed (1) the embryonic stages of a congenitally acallosal mouse mutant (strain BALB/cCF), (2) several pouch stages of a primitive acallosal marsupial, Didelphys virginiana (opossum), and (3) animals in which the "sling" had been lesioned surgically through the uterine wall in the normal embryo (strain C57BL/6J). In the acallosal mouse mutant fusion of the septal midline is delayed by about 72 hours and the "sling" does not form. Although the would-be callosal axons approach the midline on schedule, they do not cross. Instead, the callosal fibers whirl into a pair of large neuromas adjacent to the longitudinal fissure. Similarly, in the opossum, fusion of the medial septal walls and formation of the glial "sling" are also lacking. However, in this species, instead of traveling dorsally, the "callosal" axons turn ventrally and pass contralaterally by way of the anterior commissure pathway. Surgical disunion of the glial "sling" also resulted in acallosal individuals. The callosal pathology in these affected animals mimicked exactly that of the genetically lesioned mutant. Our observations suggest that many different types of oriented glial tissues exist within the embryonic neural anlage. We propose that such tissues have the ability to influence the directionality of axonal movements and, thereby, play a crucial role in establishing orderly fiber projections within the developing central nervous system.

Agenesis of Corpus Callosum↗
PubMed1982

Biochemical characterization of a second family of human Ia molecules, HLA-DS, equivalent to murine I-A subregion molecules.

In mice, two families of structurally distinct Ia molecules, one designated I-A and the other I-E, have been identified and characterized. The HLA-DR molecules represent one family of human Ia molecules equivalent to the murine I-E molecules on the basis of amino acid sequence homology. We describe the isolation and biochemical characterization of a second family of human Ia molecules, designated HLA-DS for second D-region locus, equivalent to the murine I-A molecules. The human HLA-DS molecules consist of two polypeptide chains, DS alpha (37,000 mol wt) and DS beta (29,000 mol wt), with 73% amino acid sequence identity to the murine I-A molecules. Furthermore, the HLA-DS molecules are closely linked genetically to HLA-DR molecules, a situation analogous to that observed in mice. The similarity in molecular weights of the DR and DS molecules might explain why others have failed to identify the latter in man.

Alkylation↗
PubMed1982

Peptide map comparisons of similar serologically defined HLA-DR antigens isolated from different lymphoblastoid cell lines.

In these studies, we have examined the possibility that DR subtypes, closely related to each other in structure, compose the major DR allotypic groups. The structures of DR molecules, isolated from pairs of cell lines that had the same serologically defined HLA-DR type, were compared by peptide mapping. HLA-DR molecules isolated from pairs of cell lines in which both members were either DR1, DR2, or DR7 were identical. However, DR molecules isolated from cell lines LG-29 (DR5) and LG-38 (DR5) displayed two distinct differences in their small (beta) subunits. This number of differences, two of 15 peptides or 15%, is much fewer than is observed between DR allotypes (approximately 50%) and suggests that at least two subtypes exist within the DR5 allotype family.

Animals↗
PubMed1982

Simultaneous quantitation of quinidine, procainamide, and N-acetylprocainamide in serum by gas-liquid chromatography with a nitrogen-phosphorus selective detector.

We describe a single-run method for quantitating quinidine, procainamide, and N-acetylprocainamide, involving gas-liquid chromatography with a nitrogen-phosphorus selective detector. Within-run precision (CV) was 3% (x = 2 mg/L, n = 20), 6.9% (x = 4 mg/L, n = 10), and 1.5% (x = 8 mg/L, n = 8) for quinidine; 7.7% (x = 4 mg/L, n = 14), 1.6% (x = 8 mg/L, n = 16), and 2.3% (x = 12 mg/L, n = 12) for procainamide; and 6.3% (x = 5 mg/L, n = 6), 3.6% (x = 10 mg/L, n = 20), and 4.0% (x = 20 mg/L, n = 10) for N-acetylprocainamide.l Between-run precision was 3.0%(x = 2 mg/L, n = 20), 7.0% (x = 4 mg/L, n = 9), and 2.8% (x = 8 mg/L, n = 9) for quinidine; 4.7% (x = 4 mg/L, n = 10). 3.3% (x = 8 mg/L, n = 20), and 1.9% (x = 12 mg/L, n = 10) for procainamide; and 9.3% (x = 5 mg/L, n = 6), 4.3% (x = 10 mg/L, n = 20), and 3.8% (x = 20 mg/L, n = 10) for N-acetylprocainamide. Tube stoppers that contain a rubber plasticizer interfere with the technique. Clinical application and correlation with drug concentrations by this technique are discussed.

Acecainide↗
PubMed1982

Vitamin D uptake by the perfused rat liver is determined by its transport protein.

Radiolabelled vitamin D3 and 25(OH)vitamin D3 (25(OH)D) were added to an isolated perfused rat liver, bound either to lipoproteins or lipoprotein-free plasma. The disappearance of vitamin D and 25(OH)D from the perfusate was determined. When vitamin D or 25(OH)D were added to the perfusate on lipoproteins there was a rapid decline in the amount present in the perfusate, as compared to when they were added bound to lipoprotein-free plasma. The uptake of vitamin D and 25(OH)D by the liver from lipoproteins was associated with a transfer of radioactivity from the lipoprotein portion to the lipoprotein-free portion of the perfusate. These results demonstrate the importance of the vitamin D transport protein to its uptake by the liver.

Animals↗
PubMed1982

Unmasking of isolated hypoaldosteronism after renal allotransplantation in familial Mediterranean fever.

A patient with familial Mediterranean fever and renal amyloidosis was maintained on intermittent hemodialysis for chronic renal failure. After renal allotransplantation, he became weak, lost 12 kg in weight over 7 wk, and developed marked orthostatic hypotension. His symptomatic volume depletion responded dramatically to i.v. 0.9% NaCl. Metabolic balance studies showed that he was in negative Na balance (on a 44 mEq/24 h Na diet, he excreted 71 mEq/24 h in his urine), which was corrected by mineralocorticoid therapy. Renin-aldosterone studies demonstrated a hyperreninemic hypoaldosteronism with normal glucocorticoid secretion. The patient probably suffered from amyloidosis selectively involving the glomerulosa zone of his adrenal cortices. While on dialysis he was anuric and therefore not volume depleted, but after successful renal allotransplantation the diuresis of the functioning kidney unmasked his mineralocorticoid deficiency which manifested as symptomatic volume depletion.

Adult↗
PubMed1981

Axonal guidance during development of the optic nerve: the role of pigmented epithelia and other extrinsic factors.

It is well established that a congenital lack of ocular melanin (albinism) can lead to developmental abnormalities of the central visual pathways. However, it is yet unknown how the pigmentation per se acts to influence formation of the optic projection. In order to study the possible interaction between eye pigment and optic axons during development, we have examined, with the use of serial section techniques, a series of timed embryos at stages when the ocular pigment and outgrowing axons first become apparent. Our results have demonstrated that, in mice and rats, the upper wall of the distal half of the primitive eye stalk (a region which lies along the potential route to be taken by the earliest developing nerve fibers) is transiently pigmented prior to and during the migration of the pioneer optic axons. All outgrowing neurites avoid this stretch of melanotic tissue and instead grow preferentially through a system of extracellular tunnels in the ventral, pigment-free zones of the distal eye stalk. The stalk remains unpigmented from about its midpoint and continuing toward the brain. At the pigment/pigment-free interface many of the axons shift upward from their ventral positions, forming a marginal annulus. In the chick, on the contrary, pigmentation of the stalk does not occur and as the optic axons exit the globe they grow immediately in an annulus configuration. In Xenopus, the entire stalk becomes pigmented and the optic fibers congregate in one discrete bundle of fascicles along the length of the stalk's most ventral margin. These observations suggest that melanin-producing stalk cells may play a role in controlling the topographic patterning of optic fibers within the developing nerve by inhibiting the lateral spread of axonal growth cones into or within their territory. To test this hypothesis we have charted the distribution of optic fibers in the developing optic stalks of timed albino rat embryos. Indeed, as fibers leave the mutant eye, it was found that a small but consistent number of pioneering axons (day E15) become ectopic and immediately invade nonpigmented regions (those normally pigmented and axon-free) in the distal optic stalk. Thus, the usual topographic arrangement of the collection of pioneer optic fibers is altered in the albino.

Animals↗
PubMed1981

Expression of resistance to Friend virus-stimulated erythropoiesis in bone marrow chimeras containing Fv-2rr and Fv-2ss bone marrow.

Bone marrow chimeras were formed containing mixtures of DBA/2 (Fv-2ss, Hbbdd) and B10.D2 (Fv-2rr, Hbbss) bone marrow. When these mice were infected with the polycythemia-inducing strain of Friend virus, erythropoiesis was stimulated, but the proportion of B10.D2 hemoglobin fell rapidly and newly synthesized hemoglobin was essentially all of the DBA/2 type. The treatment of infected polycythemic chimeras with phenylhydrazine lowered the hematocrit and restored the synthesis of B10.D2 hemoglobin. These results imply that B10.D2 erythroid precursors are intrinsically resistant to Friend virus-stimulated erythropoiesis. The experiments also suggest that virus-stimulated erythropoiesis is not mediated by a factor or cell-cell interactions, unless such factors or interactions do not act across strain barriers.

Alleles↗