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Biomedical subjects

R N Smith

Publications and source records attributed to R N Smith.

At least 109 records · Page 6Linked to original sources
PubMed1980

A sensitive benzodiazepine radioimmunoassay of broad specificity.

Four benzodiazepine radioimmunoassays are described, the most sensitive of which can detect sub-therapeutic levels of bromazepam, chlordiazepoxide, clobazam, demoxepam, desalkylflurazepam, desmethyldiazepam, diazepam, flunitrazepam, lorazepam, medazepam, nitrazepam, oxazepam, prazepam, temazepam and triazolam. The standard curve for diazepam has a concentration range of 0-2.5 ng ml-1. The assay is particularly applicable to blood samples of forensic interest that may be haemolysed or decomposing. A 75 microliter sample is required. The antiserum and [3H]flunitrazepam used are commercially available.

Benzodiazepines↗
PubMed1980

Heterogeneity of the tolerant state in rats with long established skin grafts.

Tolerance in rats with long established allogeneic skin grafts brought about by the neonatal inoculation of hybrid lymphomyeloid cells is immunologically heterogeneous because 2 states of tolerance may be defined operationally as fully and partially tolerant. T cells from fully tolerant donors transfer tolerance and are unresponsive in MLC, but T cells from partially tolerant donors do not transfer tolerance and are modestly responsive in MLC. A state of tolerance may exist without detectable suppression. Therefore, tolerance, traditionally defined as the permanent acceptance of an allogeneic skin graft, does not reflect a uniform immunologic state.

Animals↗
PubMed1979

Antigenic specificity and cellular mechanisms in leukocyte adherence inhibition analysis of immunity to simple proteins and hapten-protein conjugates.

The hemacytometer leukocyte adherence inhibition (LAI) assay was investigated with respect to immunological relevance, specificity, and cellular mechanisms. Humans were immunized to keyhole limpet hemocyanin, and rats were immunized to dinitrophenyl-bovine gamma-globulin. LAI analysis disclosed classic patterns of immune response kinetics. The LAI response was dose dependent in vitro with no inhibition at relatively high antigen doses. In vitro specificity in rats was restricted to the immunizing conjugate. Cells forming spontaneous E-rosettes were required for LAI reactions. Lymphokine production required the presence of E-rosette-forming cells. E-rosette-forming cells from normal donors lost adherence in the presence of lymphokine. The requirement for T-lymphocytes was confirmed in a human osteosarcoma system using independent criteria. Thus, the hemacytometer LAI depends upon T-lymphocyte collaboration via a lymphokine. It should be distinguished from the tube and microplate variants of LAI analysis because these appear to depend upon different mechanisms.

Animals↗
PubMed1978

Antitumor 1-(X-aryl)-3,3-dialkyltriazenes. 1. Quantitative structure-activity relationships vs. L1210 leukemia in mice.

Quantitative structure-activity relationships (QSAR) have been formulated for phenyl-, pyrazolyl-, and imidazolyltriazenes acting L1210 leukemia in mice. All three sets of congeners have the same ideal lipophilicity (log Po approximately 1). Electron releasing substituents increase potency; ortho substitution decreases activity. The synthesis of a number of new triazenes and some of their partition coefficients are reported.

Animals↗
PubMed1978

Autotransfusion of contaminated intraperitoneal blood: an experimental study.

Contamination of blood by bowel contents has been generally assumed as an absolute contraindication to autotransfusion. Since abdominal trauma is frequently accompanied by bowel injury and massive blood loss, a potential major use for autotransfusion has thus been precluded. To test this presumption, autologous blood grossly contaminated with feces was incubated in the peritoneal cavity and then autotransfused in dogs. The animals were hemorrhaged 20, 30, or 40% of their estimated blood volume, producing mild to severe hypovolemic shock. Reinfusion of contaminated blood had little effect on survival with 20 or 30% hemorrhage, but contamination markedly decreased survival with 40% hemorrhage:90% survived without contamination while only 30% survived with contamination. The use of antibiotics in a similar group of dogs subjected to 40% hemorrhage essentially eliminated the risk of autotransfusion: 90% of these dogs survived autotransfusion of contaminated blood.

Animals↗
PubMed1978

Leukocyte-adherence inhibition: a specific assay of cell-mediated immunity dependent on lymphokine-mediated collaboration between T lymphocytes.

The leukocyte-adherence inhibition (LAI) assay was studied to determine its immunologic relevance and identify the cell populations on which it depends. Two systems were employed: peripheral blood leukocytes from humans immunized with KLH, and lymph node cells from rats immunized with DNP-BCG. In both cases, LAI responses appeared about 3 to 4 days after immunization, reached a peak about 3 to 4 weeks later, and diminished thereafter. Reimmunization resulted in a booster-like response. LAI analysis in both systems showed dose-response dependency. Responses could be elicited only with the immunizing antigen. Virtual depletion of phagocytic cells had no effect on the response. E-rosette-forming cells gave an excellent response to KLH and also produced an active supernatant (lymphokine). Cells not forming spontaneous E-rosettes were inactive and could not produce active supernatants. Only those nonimmune cells that formed E-rosettes could respond to active supernatants. Thus, the LAI response is a specific indicator of cell-mediated immunity. T lymphocytes probably are required both at the antigen-reactive stage and at the stage of responding to the T cell-dependent lymphokine.

Animals↗
PubMed1977

The decomposition of acidic and neutral cannabinoids in organic solvents.

High-pressure liquid chromatography was used to study (a) the relative efficiencies of methanol, chloroform, light petroleum (B.P. 40-60 degrees) and methanol-chloroform (9:1) for extracting neutral and acidic cannabinoids from cannabis resin; (b) the decomposition patterns of the resulting solutions under various storage conditions, and (c) the cannabinoid profile of a cross section through a block of cannabis resin. The results show that (a) methanol is the most effective extracting solvent of those tested; (b) acidic cannabinoids in solution decompose in darkness by varying amounts depending on the temperature, solvent, storage time and particular cannabinoid; (c) neutral cannabinoids in solution are relatively stable in darkness; (d) daylight causes appreciable decomposition of both acidic and neutral cannabinoids in solution, (e) the cannabinoid profile of a resin is complex with lower levels of acidic material in the outer layers.

Cannabinoids↗