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Biomedical subjects

J Green

Publications and source records attributed to J Green.

At least 757 records · Page 42Linked to original sources
PubMedDate not supplied

Viral genome characterisation by the heteroduplex mobility and heteroduplex tracking assays.

The heteroduplex mobility assay (HMA) is a means of comparing two PCR amplicons or, in the variation known as the heteroduplex tracking assay (HTA), a means of estimating the quasispecies diversity of a viral genome. Heteroduplex assays have many applications including subtyping viral genomes, screening for low frequency variants in a population, scanning the relative genetic diversity across a genome and screening for recombinant clones. They can be used to detect dual infections, superinfections, contaminated blood products and laboratory contaminations. PCR amplicons of about 65% sequence similarity or greater will form heteroduplexes under appropriate conditions, and phylogenetic trees can be drawn from heteroduplex mobility data. While homoduplexes indicate more than 98% similarity between two DNA sequences, heteroduplexes indicate at least seven mismatches in a 500-bp amplicon, or a three-base pair gap in 1000-bp. Minority variants comprising 1% to 5% of the genome population can be detected and quantified by HTA. Thus far, heteroduplex assays have been described for HIV and other lentiviruses, hepatitis C and G viruses, Norwalk-like viruses, influenza, measles and poliovirus. They could be applied to a wide range of other viral species.

DNA, Viral↗
PubMedDate not supplied

Is there a regeneration stimulator substance in the effluent from perfused partially hepatectomized livers?

An attempt was made to transfer a stimulator substance from the perfusate of partially hepatectomized perfused livers to the portal stump of portacaval-shunted pig recipients. Blood was either cross-circulated with recipients during perfusion or was given by exchange transfusion after 4 hr perfusion. There was an increase in thymidine kinase activity and mitotic indices in biopsies from portacaval-shunted recipients whether perfusions were performed 2 or 4 days after partial hepatectomy. Blood perfused through intact livers did not enhance the regenerative response of portacaval-shunted pigs; in fact it appeared to suppress the normal small response. Approximately 10% of the portacaval-shunted recipients died acutely when perfusate was infused into the portal stump. This did not occur if saline or unperfused blood was used suggesting that some toxic substance accumulated during liver perfusion. In end-stage fulminant hepatic failure, use of blood perfused through a partially hepatectomized animal liver may provide the regenerative stimulus which often appears to be lacking.

Animals↗
PubMedDate not supplied

Tetronic 701-a novel hypocholesterolaemic agent.

The Tetronic series of polymeric surface-active agents were screened for hypocholesterolaemic activity in rats fed on a semi-synthetic hypercholesterolaemic diet. Only Tetronics 701 and 702 were active and the former was further investigated. Tetronic 701 lowered serum and liver cholesterol in rats fed on a semi-synthetic diet, with or without cholesterol, but not in rats fed on stock laboratory diet. A dose-related growth depression was observed. The compound was hypocholesterolaemic in chicks and rabbits fed on cholesterol-containing diets. The uptake of a single dose of cholesterol into liver and serum was inhibited in rats given Tetronic 701. Tetronics 701 and 702 were effective in precipitating cholesterol from mixed micelles in vitro. Non-hypocholesterolaemic Tetronics were inactive in this respect. A series of tetraesters of tetronic 701 were prepared and tested in rats fed on a semi-synthetic hypercholesterolaemic diet. Several were hypocholesterolaemic and the tetrabenzoate was of especial interest in that it depressed growth less than did Tetronic 701 itself.

Animals↗
PubMedDate not supplied

A survey of effects of gaseous and aerosol pollutants on pulmonary function of normal males.

A total of 231 normal male human subjects were exposed for 4 hr to air, ozone, nitrogen dioxide, or sulfur dioxide; to sulfuric acid, ammonium bisulfate, ammonium sulfate, or ammonium nitrate aerosols; or to mixtures of these gaseous and aerosol pollutants. Only one concentration of each pollutant was used. This study, therefore, represents a preliminary survey, intended to allow direct comparison of studies to plan future research. During exposure each subject had two 15-min exercise sessions on a treadmill at 4 mph and 10% grade. Environmental conditions were mildly stressful, i.e., temperature = 30 degrees C and relative humidity = 60%. A battery of 19 measurements of pulmonary function was performed just prior to exposure (air control); 2 hr into the exposure, following the first exercise session; 4 hr into the exposure, following the second exercise session; and 24 hr after exposure. Significant differences were noted in specific airway resistance (SRAW), forced vital capacity (FVC), and forced expiratory flow at 50% of FVC (FEF50) and in related measurements in those experimental groups exposed to ozone or to ozone plus aerosols. None of the aerosols alone, nitrogen dioxide or sulfur dioxide alone, or mixtures of nitrogen dioxide or sulfur dioxide with aerosols produced significant effects. A distribution analysis of subject responsivity to ozone gave a normal distribution among subjects not exposed to ozone, and a distribution shifted to the right and skewed to the right among those exposed to ozone alone or in mixture, with no evidence of bimodal distribution of ozone sensitivity.

Aerosols↗
PubMedDate not supplied

Bioassay of a cigarette smoke fraction. I. Examination of dose-response relations and dilution bioassay assumptions in a ciliostasis system.

Ciliostasis times of the water-soluble smoke fraction of the University of Kentucky 1R1 Reference Cigarette and experimental cigarettes were compared in the hamster tracheal ring system. Dose-response relations were critically examined, and the assumptions of a dilution bioassay were tested. The model in which a logarithmic transformation was used for both mean time to ciliostasis and smoke sample concentration gave the most satisfactory linear fit. At appropriate concentrations, the ciliostatic responses of the test tobacco smokes were found to be parallel to those of the 1R1, supporting the validity of the dilution bioassay assumptions. Details of experiments and analyses are presented as examples of some of the steps required to establish valid bioassay systems.

Analysis of Variance↗
PubMedDate not supplied

Comparison of six cannabinoid metabolite assays.

Numerous methods for the detection of urinary metabolites of marijuana constituents are available. Documentation of the sensitivity and specificity of these tests is needed before the determination of a pair of screening-confirmation tests can be made. This study used 88 clinical specimens to evaluate five commercially available marijuana metabolite methods and one new gas chromatography/mass spectrometry (GC/MS) method. The EMIT-d.a.u. test was found to have 2 to 3% unconfirmed positives when compared to the other methods evaluated. The new thin layer procedure, TOXI-LAB, was not as sensitive as the EMIT-d.a.u. procedure for some specimens, but proved to be a good confirmation for the EMIT-d.a.u. with elimination of all "unconfirmed positives." The Abuscreen (Roche) and the EMIT-st assays were positive for samples that contained larger amounts of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (11-nor-delta 9-THC-9-COOH). The Immunalysis-radioimmunoassay (RIA) was positive for all samples found positive by the GC/MS method, but the concentrations found by the two assays did not correlate. The GC/MS method was developed to use the same extraction as the thin layer procedure and provides confirmation for all procedures except 2 to 3% of the positive EMIT-d.a.u. results.

Cannabinoids↗