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Biomedical subjects

R S Chang

Publications and source records attributed to R S Chang.

At least 145 records · Page 8Linked to original sources
PubMed1979

Prolonged survival in chronic lymphocytic leukemia: a case report.

A patient with long-standing chronic lymphocytic leukemia with both humoral and cellular immunodeficiency had lymph node receptor evidence of a B lymphocyte disorder. He was also found to secrete the Epstein--Barr virus and, late in his illness, developed a markedly positive antinuclear antibody. Interrelationship of these findings may be important in the ultimate determination of the etiology and functional mechanisms in lymphocyte malignancies.

Adult↗
PubMed1979

Incidence of infectious mononucleosis at the Universities of California and Hawaii.

The observed rates of heterophil-positive infectious mononucleosis at the University of California at Davis and the University of Hawaii at Manoa were 1,212 and 37 per 100,000 students per academic year, respectively. The data collected suggest that the extraordinarily low incidence at the University of Hawaii may be due to the following factors: (1) underutilization of the student health service by students with infectious mononucleosis; (2) low proportion of Epstein-Barr virus-seronegative students; (3) high proportion of Asian students who appear to be less likely to develop heterophil-positive infectious mononucleosis; and (4) possible low efficiency in the transmission of primary Epstein-Barr virus infections.

Adolescent↗
PubMed1979

Vascular and extravascular compartments of the isolated perfused rabbit lung.

The vascular, interstitial, and cellular compartments of 15 isolated, perfused and ventilated rabbit lungs determined by a steady-state indicator-dilution procedure. Five lungs were perfused with constant pulmonary artery flow and zero left atrial pressure for more than 1 h. Edema formation was continuous and pulmonary vascular volume (PVV) decreased initially at a time when pulmonary vascular resistance (PVR) was falling. Increases in PVR were not seen until edema formation had become severe. In 10 other lungs, increases in pulmonary artery or left atrial pressure resulted in elevation of PVV and accelerated edema formation. The initially abrupt increase in PVV was followed by a more gradual increase over a 10-min period. Return of fluid to the vasculature was never observed in these studies. Labeled albumin readily entered the extravascular space but a relatively constant fraction of the interstitium remained inaccessible to albumin. No changes were found in the cellular volume during edema formation.

Animals↗
PubMed1979

Characteristics of histamine H1-receptors in peripheral tissues labeled with [3H]mepyramine.

Specific binding of [3H]mepyramine to membranes of various peripheral tissues of different species has been demonstrated. Drug specificity indicates an association with histamine H1-receptors. Of all the tissues examined brain contains the highest numbers of binding sites, while substantial levels of specific [3H]mepyramine binding are also demonstrable in some species in heart, lung, adrenal and ileum. Negligible specific [3H]mepyramine binding is observed in the liver, stomach and uterus of several species. The lesser bronchoconstricting response of the rat than of other species to histamine is paralleled by a lower number of [3H]mepyramine binding sites in rat lung than in other species. However, similar numbers or [3H]mepyramine binding sites occur in ileal membranes of rat, guinea pig and rabbit, although contractile effects of histamine vary in these species. In the quinea-pig ileum, [3H]mepyramine binding is most concentrated in the longitudinal muscle itself where histamine exerts its predominant contractile effects. In the bovine adrenal gland, [3H]mepyramine binding is more abundant and has higher affinity for drugs in the medulla than in the cortex.

Adrenal Glands↗
PubMed1978

Benzodiazepine receptors: labeling in intact animals with [3H] flunitrazepam.

[3H]Flumitrazepam appears to label specific benzodiazepine receptors in vitro after i.v. injection in mice. Benzodiazepine potencies in reducing [3H]flunitrazepam binding in vivo correspond to pharmacological potencies and parallel relative affinites for [3H]flunitrazepam binding sites in isolated brain membranes. However, 50% occupation of [3H]-flunitrazepam sites by benzodiazepines in vivo requires brain concentrations of the drugs about 1000 times higher than their Ki values for the binding sites in vitro. In pharmacologically active doses sodium pentobarbital, strychnine, picrotoxin and bicuculline fail to influence [3H] flunitrazepam binding in vivo.

Animals↗
PubMed1978

Histamine H1 receptors identified in mammalian brain membranes with [3H]mepyramine.

The antihistamine [3H]mepyramine binds to H1 histamine receptors in mammalian brain membranes. Potencies of H1 antihistamines at the binding sites correlate with their pharmacological antihistamine effects in the guinea pig ileum. Specific [3H]mepyramine binding is saturable with a dissociation constant of about 4 nM in both equilibrium and kinetic experiments and a density of 10 pmol per gram of whole kinetic experiments and a density of 10 pmol per gram of whole brain. Some tricyclic antidepressants are potent inhibitors of specific [3H]mepyramine binding. Regional variations of [3H]mepyramine binding do not correlate with variations in endogeneous histamine and histidine decarboxylase activity.

Amines↗
PubMed1978

Oropharyngeal excretion of Epstein-Barr virus by patients with lymphoproliferative disorders and by recipients of renal homografts.

In an attempt to associate oropharyngeal excretion of Epstein-Barr (EB) virus with lymphoproliferative disorders other than infectious mononucleosis, we tested throat gargles collected from adult subjects for the EB virus. Nine (16%) of 55 healthy persons were positive. High EB virus-excretion rates were found among patients with active acute lymphocytic leukemia (6/6, 100%), among renal homograft recipients during the third to 12th month after transplantation (26/30, 87%), and among critically ill patients with leukemia-lymphoma (14/19, 74%). Moderately high excretion rates were found among patients with myeloma (7/16, 44%), patients with poorly differentiated lymphocytic lymphoma (5/11, 44%), critically ill patients with solid cancers (15/37, 41%), and patients with chronic myelogenous leukemia (8/21, 38%). Our data suggested that the higher than normal excretion rate is realted to the basic disease process and to the general health status but not to the duration of cancer chemotherapy.

Antineoplastic Agents↗
PubMed1977

Postsynaptic membranes in the electric tissue of Narcine: IV. Isolation and characterization of the nicotinic receptor protein.

The nicotinic receptor protein of the electric tissue of Narcine was purified in several different media by partial isolation of postsynaptic membranes and affinity chromatography. Protease inhibitors were found to be necessary to prevent degradation of the protein, and both EDTA and Tris buffer were used in addition to prevent intramolecular crosslinking of 44,000 and 58,000 dalton subunits by tissue factors. The intact protein was found to have a molecular weight close to 400,000, and appears to be composed of four subunits of 44,000 daltons, two to three of 48,000, one of 58,000 and one of 65,000. All the subunits are glycoproteins and their amino acid compositions show similar hydrophobicity and acidity, suggesting similar positioning in postsynaptic membranes. Crosslinking experiments showed that acetylcholine and alpha-bungarotoxin bind to the smallest subunit, and suggest the juxtaposition of at least two of these subunits, and of all four toxin molecules bound to a receptor molecule. Morphological studies of the protein in membranes and after purification indicated cylindrial molecules with central cores.

Acetylcholine↗
PubMed1977

Effect of osmolality on red blood cell viscosity and transit through the lung.

The mean transit times of labeled red blood cells and albumin were compared in eight isolated rabbit lungs perfused with physiological albumin solutions. The osmolality of these solutions was adjusted by altering the concentration of sodium chloride. The ratios of the mean transit times of injected red blood cells to those of albumin increased as perfusion osmolality increased from hypotonic to isotonic and from isotonic to hypertonic levels. This change occurred despite a decline in pulmonary vascular resistance and red blood cell size as osmolality was increased. Red blood cell viscosity (determined with a cone-plate viscometer) increased with osmolality and it was concluded that this change of viscosity impaired the relative rate of red blood cell transit through the lungs. Passage of red blood cells through rigid homoporous membranes appeared to be related primarily to red cell size rather than vascosity. These observations suggest that both red blood cell viscosity and capillary distensibility play an important role in determining the velocity of red blood cells through the capillaries.

Animals↗
PubMed1976

In vitro stimulation of lymphocytes of donors seronegative for Epstein-Barr virus by preparations of inactivated Epstein-Barr virus.

Heat-inactivated preparations of Epstein-Barr virus stimulated human lymphocytes as assayed by incorporation of [(3)H]thymidine. The inactivated Epstein-Barr virus stimulated the lymphocytes of all five seropositive donors, 11 of 14 seronegative donors (aged eight to 26 years), and none of 15 neonates. Control antigens prepared from a human lymphoid cell line devoid of the Epstein-Barr virus genome did not stimulate the lymphocytes of seronegative donors. Fetal calf serum at the concentration used for suspension of Epstein-Barr virus did not stimulate or only minimally stimulated the lymphocytes of seronegative donors. The reactivity of the histocompatibility antigens found on human lymphocytes was abolished by procedures used for inactivation of the virus.

Adolescent↗