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Biomedical subjects

V Marks

Publications and source records attributed to V Marks.

At least 253 records · Page 14Linked to original sources
PubMed1978

Prolongation and enhancement of serum methotrexate concentrations by probenecid.

The disappearance of methotrexate (MTX) from the serum after an intravenous bolus injection and intravenous infusion was studied over 24 hours in eight and four patients respectively. Probenecid given at the same time as the bolus injection delayed the disappearance of MTX from the serum and resulted in enhanced concentrations throughout the 24 hours studied. At 24 hours the mean concentration was four times higher than in patients not given probenecid. Overall serum concentrations were even greater than those in patients who had received MTX by intravenous infusion. We suggest that smaller doses of MTX may be given and treatment costs thereby reduced if probenecid is given in addition.

Adult↗
PubMed1978

The effect of induced hyperglucagonaemia on the Zucker fatty rat.

The effect of chronic treatment with a long-acting glucagon preparation on liver glucagon and insulin receptors, adenylate cyclase and plasma lipids has been examined in Zucker fatty rats (fa/fa) and their lean littermates (Fa/-). Liver insulin and glucagon receptors were examined using radioreceptor assay techniques. Neither fatty nor lean rats showed any change in insulin receptors after glucagon treatment. Glucagon receptors of the fatty rats showed a 33% drop in the number of the glucagon receptors after glucagon treatment, whilst there was no such change in the lean group. Plasma membranes of the treated fatty rats and their controls bound only 50% as much insulin per mg of liver membrane protein as those of the treated lean rats and their controls. Glucagon treatment raised plasma NEFA in lean rats and reduced them in fatty ones. Plasma cholesterol levels were reduced in both groups of animals as were plasma triglycerides, though to a lesser degree in fatty than in lean animals. Glucagon treatment increased basal and stimulated adenylate cyclase activity in the lean rats and even more so in the fatty ones. The data lend no support to the concept that hypertriglyceridaemia in fatty Zucker rats is a consequence of abnormal glucagon responsiveness.

Adenosine Triphosphatases↗
PubMed1978

Prednisone or prednisolone for the treatment of chronic active hepatitis? A comparison of plasma availability.

1 The plasma availability of prednisolone after oral doses of prednisolone and its precursor, prednisone, were compared in ten normal controls and twenty-five patients with chronic active hepatitis by estimation of the area under the plasma concentration--time curve for the drug (AUC). 2 In controls, values for AUC were significantly more variable after prednisone than prednisolone, and two subjects showed markedly inefficient conversion of prednisone to prednisolone. In patients, variability was similarly wide after both preparations, but overall bioavailability after both prednisone and prednisolone was similar to that found in controls, although three patients showed subnormal values after both preparations, possibly as a result of impaired intestinal absorption. 3 Patients with biochemical and histological evidence of active hepatocellular necrosis showed evidence of impaired activation of prednisone, but this was compensated for by a decreased rate of elimination of prednisolone from the plasma. 4 It is concluded that plasma prednisolone levels will be more predictable after prednisolone than after prednisone in subjects without hepatic dysfunction. In the presence of liver disease, because of the marked variability in plasma prednisolone levels after either drug, estimation of these could be of value in those patients whose disease cannot be controlled by normal maintenance doses.

Adult↗
PubMed1978

Radioimmunoassay of gastric inhibitory polypeptide.

A radioimmunoassay for the measurement of gastric inhibitory polypeptide (GIP) in unextracted plasma in man has been developed using a rabbit antiserum raised against porcine GIP. Porcine GIP was employed also as standard and to produce a 125I-labelled tracer. The assay was able to distinguish 110 pg/ml GIP from zero in plasma samples. Negligible cross-reactivity was demonstrated with cholecystokinin, insulin, pancreatic polypeptide, glucagon, secretin, and vasoactive intestinal polypeptide. The mean overnight fasting plasma GIP level in 28 normal subjects was 203 pg/ml (range: undetectable--420 pg/ml). Plasma GIP levels rose, within 45 minutes of eating a mixed meal, to a mean level of 1573 pg/ml.

Animals↗
PubMed1978

Radioimmunoassay of amitriptyline and nortriptyline in body fluids.

A radioimmunoassay for the measurement of amitriptyline and nortriptyline in serum, saliva, and urine is described. The sensitivity of the assay is such that 0.5 ng/ml of drug can be measured, although the assay does not distinguish between amitriptyline and nortriptyline. Other tricyclic compounds cross-react with the antiserum to varying degrees, but the metabolites of amitriptyline did not significantly cross-react. Total tricyclic compounds were detected in serum and saliva after single oral doses of amitriptyline, although the absorption was slow.

Amitriptyline↗
PubMed1978

Radioimmunoassay of methotrexate: use of 75Se-labelled methotrexate.

75Se-labelled methotrexate has been used as the radiolabel in a radioimmunoassay for methotrexate and its use compared with that of 3H-methotrexate. The gamma-labelled drug has proved to be extremely reliable and easier to use than 3H-methotrexate. Results obtained with it compare well with those obtained with tritiated drug. There are practical advantages in using a gamma emitter, and it is suggested that the modified radioimmunoassay is invaluable for routine monitoring of methotrexate in patients undergoing chemotherapy with the drug.

Cross Reactions↗
PubMed1978

Cobalt:a review.

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Alloys↗
PubMed1978

Double-antibody enzyme immunoassay for nortriptyline.

beta-D-Galactosidase (EC 3.2.1.23) from Escherichia coli was conjugated to desmethylnortriptyline by means of a bifunctional cross-linking reagent, dimethyl adipimidate, and used in a double-antibody immunoassay for nortriptyline. Eighty percent of the enzyme activity was retained after conjugation; 75% of the enzyme was conjugated to desmethylnortriptyline. In the final immunoassay the enzyme activity of the bound fraction was determined with o-nitrophenyl-beta-D-galactopyranoside as substrate. The sensitivity, precision, and simplicity of the enzyme immunoassay compared favorable with that of a published radioimmunoassay method. Results for nortriptyline in plasma samples correlated well with those determined by either radioimmunoassay or gas-chromatography.

Cross Reactions↗
PubMed1977

Lunchtime gin and tonic a cause of reactive hypoglycaemia.

10 healthy young subjects drank, on three separate occasions, the equivalent of three gin and tonics containing 50 g alcohol and 60 g sucrose, gin and "Slimline" tonic containing 50 g alcohol and 0.5 g sucrose, or tonic alone containing 60 g sucrose. Their behaviour, symptoms, blood-glucose, and plasma-insulin were monitored for 5 hours. Both of the alcohol-containing drinks caused mild-to-moderate inebriation, but gin and slimline tonic had no significant effect on either blood-glucose or plasma-insulin levels. Gin and tonic provoked a greater insulinaemia and more profound reactive hypoglycaemic response than tonic alone, and in 3 of the subjects this was associated with the appearance of neuroglycopenic symptoms. Alcohol-mediated reactive hypoglycaemia may contribute significantly to motor-car accidents in the late afternoon at a time when blood-alcohol levels have fallen below the legal limit.

Alcoholic Beverages↗