PubMed Health⌕ Search

Biomedical subjects

R S Chang

Publications and source records attributed to R S Chang.

At least 163 records · Page 9Linked to original sources
PubMed1976

Nicotine-like actions of cis-metanicotine and trans-metanicotine.

The actions of the cis- and trans-isomers of metanicotine were observed on isolated rabbit aortic strips and ileal segments. The data are interpreted as showing a nicotine-like action on these preparations for both cis-metanicotine and trans-metanicotine. This hypothesis is supported in part by the demonstration that the action of the metanicotine isomers was affected by hexamethonium, cocaine, phenotolamine, reserpine and atropine in a manner similar to that previously seen in studies with nicotine. In dose-response studies on the aortic strip, trans-metanicotine was significantly less active than nicotine. cis-Metanicotine in turn was less active than trans-metanicotine and nicotine. Additionally, four pyridino compounds, 3-pyridylacet acid, N-(3 pyridlyacetyl) glycine, nicotinuric acid and trans-4-(3-pyridyl)-3-butenoic acid, were tested for both agonist and antagonist activity. No stimulatory activity was found with these compounds in either the aortic strip or ileal preparations. In aortic strip preparations, pretreatment with either 3-pyridylacetic acid or N-(3-pyridylacetyl) glycine provided a moderate to marked reduction in the contractile response to trans-metanicotine, whereas pretreatment with trans-4-(3-pyridyl)-3-butenoic acid caused a slight reduction.

Animals↗
PubMed1975

Permselectivity of the glomerular capillary wall to macromolecules. I. Theoretical considerations.

The transport of macromolecules across the renal glomerular capillary wall has been described theoretically using flux equations based on (a) restricted transport through small pores, and (b) the Kedem-Katchalsky formulation. The various assumptions and limitations inherent in these two approaches are discussed. To examine the coupling between macromolecular solute transport and the determinants of glomerular filtration rate, these flux equations were combined with mass balance relations which allow for variations in the transmembrane driving forces along a glomerular capillary. It was predicted, using both pore theory and the Kedem-Katchalsky equations, that fractional solute clearance should be strongly dependent on the determinants of glomerular filtration rate when convection and diffusion both contribute to solute transport. When convection becomes the sole mechanism for transcapillary solute transport, however, fractional solute clearance is essentially independent of changes in the determinants of glomerular filtration rate. Consequently, unless diffusion is absent, fractional solute clearances alone are insufficient to characterize the permselective properties of the glomerular capillary wall, since these values may be altered by changes in glomerular pressures and flows as well as changes in the properties of the capillary wall per se.

Animals↗
PubMed1975

Suppression of spontaneous in vitro transformation of autologous leukocytes by plasma from convalescent and postconvalescent infectious mononucleosis patients.

All 14 plasma samples from 13 convalescent and postconvalescent infectious mononucleosis (IM) patients suppressed the spontaneous in vitro transformation of autologous leukocytes. In contrast, only 2 of 8 plasma samples from patients with acute IM suppressed this transformation. All 7 patients whose blood was tested both in the acute and convalescent or postconvalescent phases of IM showed either a conversion in transformation suppression status from negative to positive or an increase in the strength of transformation suppression. Thus recovery from IM appeared to be associated with the ability of plasma to suppress the in vitro spontaneous transformation of autologous leukocytes.

Antibodies, Viral↗
PubMed1972

Interferon production by human cells in vitro.

The relative capacity of several types of human cells and tissue to produce interferon was studied. Types of cells and tissue included were fibroblasts from embryos, foreskins, and biopsied skins; amnion cells; peripheral leukocytes; established lymphoid cell lines; established heteroploid cell lines; and chorioamniotic membrane. When Newcastle disease virus was used as the inducer, fibroblasts and amnion cells produced more interferon per 10(6) cells than leukocytes, lymphoid cells, and heteroploid cells. Only minor variations in interferon-producing capacity were observed among fibroblasts from 36 persons. Culture passage level, cell concentration, and inducer were factors that significantly affected interferon production.

Adult↗