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Biomedical subjects

V Marks

Publications and source records attributed to V Marks.

At least 91 records · Page 5Linked to original sources
PubMed1989

Biosynthetic human growth hormone in burned patients: a pilot study.

A 15-day, open trial was conducted in 12 adult burned patients of whom six were randomly allocated to form a control group and six to receive biosynthetic human growth hormone (somatropin). All were fed enterally and treated according to a standard burn protocol. The mean age, burn size, energy and nitrogen intakes were well matched in each group. The resting energy expenditures (REE) were comparable in each group and the REEs exceeded the calculated basal energy expenditures by a mean of 36.8 +/- 4.1 per cent for both groups. Blood urea values were significantly lower in somatropin-treated patients but there was no significant difference in nitrogen balance, protein oxidation or the rate of plasma protein recovery between the two groups. The basal plasma insulin concentration and basal insulinogenic index were significantly higher in somatropin-treated patients but insulin release, in response to injected glucose, was comparable in both groups. All patients had impaired glucose disposal due to insulin resistance but the area under the glucose curve increased significantly during somatropin treatment. It is concluded that somatropin administration did not significantly improve nutrition in burned patients but has been shown to exacerbate the existing insulin resistance.

Adult↗
PubMed1989

Enhanced chemiluminescent enzyme immunoassay for cannabinoids in urine.

An enhanced chemiluminescent enzyme immunoassay was developed for the detection of cannabinoids in urine. It utilises an antiserum specific for tetrahydrocannabinol and its major metabolite, a donkey anti-sheep antiserum and a horseradish peroxidase labelled antigen conjugate. The bound enzyme is detected via its catalytic activity on the chemiluminescent luminol-H2O2 reaction in the presence of an enhancer. This immunoassay employs mild experimental conditions and is extremely sensitive (0.13 microgram l(-1), making it suitable for the detection of cannabinoids in samples obtained several days following drug use. None of several medicinal and other drugs of abuse tested interfered in the assay. Greater sensitivity and simplicity make it a feasible non-isotopic alternative to radioimmunoassay and it is amenable to automation and routine screening to large sample batches.

Cannabinoids↗
PubMed1989

Xylitol vs glucose: effect on the rate of gastric emptying and motilin, insulin, and gastric inhibitory polypeptide release.

The effect of xylitol and glucose on the rate of gastric emptying and intestinal transit and on motilin, gastric inhibitory polypeptide (GIP), and insulin release were studied in human volunteers. A single oral dose of 200 mL water containing 30 g glucose or 30 g xylitol, mixed with a 99mtechnetium-tin (99mTc-Sn) colloid, was used. Similar dosing without the label was used in motilin, GIP, and insulin studies. Xylitol decreased the rate of gastric emptying but concomitantly accelerated intestinal transit compared with glucose. The half-times for gastric emptying were 77.5 +/- 4.6 and 39.8 +/- 3.4 min after ingestion of xylitol and glucose solutions, respectively. Glucose suppressed motilin and stimulated GIP secretion; xylitol stimulated motilin secretion but had no effect on GIP, which is currently the main candidate for the role of enterogastrone. The accelerated intestinal transit and increase in plasma motilin observed after xylitol ingestion were thought to be causally related to the diarrhea and gastrointestinal discomfort produced by it.

Colloids↗
PubMed1989

Bone disease in chronic alcoholism: the value of plasma osteocalcin measurement.

Osteoporosis is more common in chronic alcoholics than in age-matched controls. Possible aetiological factors are: malabsorption of calcium and vitamin D; liver disease and abnormal parathyroid function. The possibility that alcohol may directly affect osteoblastic function has, however, received little attention. We measured plasma osteocalcin, a protein synthesised specifically by osteoblasts, in chronic alcoholics. Our data show that these have low plasma osteocalcin but normal calcium, magnesium and parathormone, which suggest that alcohol may be directly toxic to osteoblasts.

Adult↗
PubMed1989

The pharmacokinetics of caffeine and its dimethylxanthine metabolites in patients with chronic liver disease.

1. Serum and salivary concentrations of caffeine (1,3,7-trimethylxanthine) and its dimethylxanthine metabolites were measured in 10 healthy control subjects and in 19 patients with cirrhosis, for up to 96 h following a 400 mg oral caffeine load. 2. Serum and salivary caffeine concentrations correlated significantly (r = 0.954; P less than 0.001) and no significant differences were observed in the pharmacokinetic data derived from the respective concentration-time curves. 3. In the control subjects, basal salivary caffeine concentrations did not exceed 0.4 mg l-1. The median (range) basal salivary caffeine concentrations in patients with compensated cirrhosis (n = 10), 0.2 (0-0.7) mg l-1 and decompensated cirrhosis (n = 9), 0.7 (0-5.8) mg l-1, were not significantly different from control values, although three patients with decompensated cirrhosis had basal salivary caffeine values above 2.0 mg l-1. 4. In the patients with compensated cirrhosis, the median peak salivary caffeine concentration, 10.9 (8.2-16.5) mg l-1 was significantly greater than in controls, 7.1 (4.7-11.8) mg l-1 (P less than 0.01) and the median apparent volume of distribution was significantly reduced, 0.38 (0.19-0.49) vs 0.41 (0.23-0.63) l kg-1 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The reduction of peripheral insulin concentrations in obese subjects following a hypocaloric diet: reduced pancreatic secretion or increased hepatic extraction?

The fasting hyperinsulinaemia characteristic of obesity is due to pancreatic hypersecretion and is accompanied by a corresponding increase in plasma C-peptide concentrations. The exaggerated plasma insulin and C-peptide responses to oral glucose in obese subjects which is greater for insulin than C-peptide suggests that the stimulated hyperinsulinaemia is due to both pancreatic hypersecretion and decreased fractional hepatic extraction of insulin. In obese subjects fasting and stimulated insulin concentrations, but not those of C-peptide, are lower after 3 weeks of energy restriction than before it. This reduction in fasting and stimulated insulin levels is, therefore, due to an increase in the fractional extraction of insulin by the liver rather than to a reduction in pancreatic secretion as had previously been supposed.

Adult↗
PubMed1989

Impaired renal tubular function in chronic alcoholics.

Despite the well known effects of chronic alcohol abuse on the gastrointestinal, cardiovascular, nervous and endocrine systems, little information is available on its effect on renal function. To assess renal function we measured urinary excretion of albumin, alpha 1 microglobulin and retinol binding protein in 30 chronic alcoholic patients. Our data shows that 40% of chronic alcoholic patients have impaired renal tubular function.

Adult↗
PubMed1989

[Locoregional chemotherapy of liver tumors].

Experiences with different protocols of intraarterial chemotherapy in the treatment of primary or secondary liver malignancies in 38 cases were reported. The follow-up period was two years in all patients. Complications due to chemotherapy were observed only in very few patients. In 15 patients complications during chemotherapy from the implantable infusion system (Port a Cath) like leckage (n = 8), thrombosis of the system (n = 4), thrombosis of the hepatic artery (n = 1) and aneurysma of the hepatic artery (n = 2) occurred. Highest survival rates for the first and second year were achieved in patients with resectable liver metastases from colorectal cancer. A prophylactic implantation of an intraarterial catheter can be considered in patients in which a liver resection was performed because of multilocular uni- or bilateral metastases. CEA- and CA-19-9 levels did not correspond to the tumor progress in many cases.

Adult↗
PubMed1989

An evaluation of Fecatwin/Feca EIA; a faecal occult blood test for detecting colonic neoplasia.

A combination guaiac and immunological test Fecatwin/Feca EIA for the detection of faecal occult blood was used in the investigation of 535 symptomatic patients in order to assess the value of this combined test in the detection of colorectal neoplasia. The addition of the immunological part of the test led to an improvement in specificity for colorectal cancer from 80% to 91% and an increase in the positive predictive value of the test for colorectal cancer from 14% to 24%. However, there was a fall in sensitivity from 75% to 67%. There was no substantial advantage in the addition of the immunological part of the test to justify the extra laboratory workload incurred.

Colonic Neoplasms↗
PubMed1988

An immunisation protocol which enhances the frequency of antigen-specific monoclonal antibody production.

An immunisation protocol has been developed for small molecular weight antigens which results in a high percentage of specific hybridomas being produced after cell fusion. An enzyme-linked immunosorbent assay (ELISA) was developed for screening the desired antibodies in the culture supernatants. A conventional immunisation regimen was followed by doses of antigen in sterile water on each of the last 4 days before fusion. A range of antigen doses was used and the specific efficiency of fusion was increased by selection of the optimum amount. The antigen used as a model antigen in these experiments was biosynthetic human insulin.

Animals↗
PubMed1988

An ELISA for the measurement of VP16 (etoposide) in unextracted plasma.

An ELISA for the anti-cancer drug VP16 in unextracted plasma has been developed using VP16-thyroglobulin-coated microtitre plates, a sheep anti-VP16 serum, and a donkey anti-sheep HRPO-labelled second antibody. The sensitivity of the assay was 0.5 ng/ml, providing a detection limit of 0.1 microgram VP16/ml plasma. Plasma interference effects were negligible and therefore the standard curve could be set up in assay buffer. A good correlation was obtained between the ELISA and established HPLC and RIA methods. No evidence was found of significant levels of cross-reacting metabolites in plasma samples obtained from patients receiving VP16 therapy. The antiserum did not cross-react with the epiaglycone of VP16.

Cross Reactions↗
PubMed1988

Intestinal absorption of oxalate by xylitol-treated rats and mice.

The absorption of 14C-labelled oxalic acid was studied in Wistar rats, CD-1 mice and NMRI mice. Oxalic acid in solution was given to the animals by gavage either with water alone or with 0.625 g/kg b.w. of xylitol. Both xylitol-adapted animals and animals not previously exposed to xylitol were used. Adaptation to xylitol diets enhanced the absorption and urinary excretion of the label (oxalic acid) in both strains of mice but not in rats. Earlier studies have indicated a high incidence of bladder calculi in mice but not in rats fed high amounts of xylitol. The results of the present study offer one likely explanation for the increased formation of bladder calculi as a result of oversaturation of urine with oxalate.

Administration, Oral↗