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Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 649 records · Page 36Linked to original sources
PubMed1985

[Calcium oxalate monohydrate (whewellite) renal lithiasis].

Pure calcium oxalate monohydrate lithiasis is rare--about 5 to 10% of total renal lithiases. The proportion is the same in men and women. Pure calcium oxalate stones are a polished dark brown color, and are very hard. They are visualized radiologically as regular and homogeneous. From a biological standpoint, this type of stone is frequently associated with normal calciuria and oxaluria. Pure calcium oxalate monohydrate stones rarely evolve.

Adult↗
PubMed1985

[Increase in urinary uric acid in the rat following portacaval shunt. The action of clofibrate].

Two successive experiments on rats confirm that a portocaval shunt leads to a substantial increase in uricosuria, which does not climax in the first week postoperatively. Clofibrate, an inductive liver enzyme, significantly reduces the uricosuria, but only after a certain timelag. Uricosuria, the degree of which varies with individual rats, leads to crystallization of uric acid, mainly in the form of ammonium urate, but polyuria secondary to portocaval shunt tends to inhibit the crystallization. A reduced water intake one day out of two facilitates the crystallization after a portocaval shunt.

Animals↗
PubMed1985

Anthropometric cut-off points for diagnosis of malnutrition: are they applicable in developing countries? A study in healthy African adults, North-East Nigeria.

Anthropometric evaluations of the upper limb were performed on 614 healthy African adults who were employees of two hospitals in Maiduguri, North-East Nigeria. Measurements were related to reference standards of Jelliffe (1966) and to centiles derived from the United States Health and Nutrition examination survey of 1971 to 1974. A large proportion of subjects, particularly men, fell below the 5th centile and 90 per cent of the Jelliffe reference. These cutoff points, which are often taken to indicate nutritional depletion in developed countries, cannot be used as similar nutritional indicators in this part of Africa.

Adolescent↗
PubMed1985

Malnutrition in African patients with pulmonary tuberculosis.

Anthropometric measurements and hand-grip dynamometry were performed on 84 (52 male) African patients, aged 18-50 years, who were consecutively admitted to the General Hospital, Maiduguri, with pulmonary tuberculosis. Nutritional findings were related to clinical features, and also compared with those obtained in healthy age- and sex-matched hospital paramedical staff. Weight, subcutaneous fat, muscle mass and hand-grip strength were all significantly reduced in tuberculosis patients compared with controls (P less than 0.001). Patients with extensive radiological disease also had reduced measurements compared with those who had disease limited to one or two lobes (P less than 0.05). The results indicate that patients with pulmonary tuberculosis have a high degree of undernutrition, and further study is required to determine whether nutritional improvement accompanies successful chemotherapy.

Adolescent↗
PubMed1985

[Calcium oxalate stones and hyperoxaluria secondary to treatment with pyridoxilate].

Pyridoxilate is a salt formed from glyoxylic acid and pyridoxine. It has been used therapeutically as an antianoxic drug in the treatment of various arterial complaints. Its use is based theoretically on its ability to block the conversion of glyoxylic acid into oxalic acid. The following cases suggest, however, that pyridoxilate can cause stones. Intraperitoneal injection of glyoxylate in doses of 130 mg/kg will cause oxalate stones in rats. The same effect results from injection of 427 mg/kg pyridoxilate (i.e. an equivalent dose of glyoxylate). In human subjects, intravenous injection of 200 mg of pyridoxilate results in a fourfold increase in the urinary oxalic acid content in the two hours following the injection. Thirteen cases of chronic progressive oxalate stone disease have recently been reported in patients receiving a prolonged course of pyridoxilate at 450 to 600 mg daily. Eight of these patients had no previous history of lithiasis. Oxaluria levels of 80 to 100 mg daily are observed in all cases of lithiasis in patients receiving pyridoxilate. The levels fell after cessation of the pyridoxilate treatment, and reverted to normal (30 mg/24 hours) in all but three patients. These three patients maintained levels of close to 50 mg and all three had a previous history of urolithiasis.

Aged↗
PubMed1985

[Iatrogenic oxalic lithiasis caused by pyridoxilate].

Piridoxilate (P) is given in cases of angina pectoris or arteritis. It is an intramolecular association of glyoxylic hemiacetal salts of pyridoxine. Glyoxylate has a membranous protective action; pyridoxine is used for the theoretical purpose of preventing oxidation of glyoxylic acid to oxalic acid. We have observed 12 patients with an active calcium oxalate lithiasis who had been taking P for many years. Hyperoxaluria was present in all patients and decreased significantly when the drug was interrupted. Significant hyperoxaluria was also observed in volunteers after ingestion of P (600 mg per day) or i.v. (200 mg). We have obtained experimental calcium oxalate urinary stones after intraperitoneal injection of P to Wistar rats. Piridoxilate represents an important lithogenic factor.

Aged↗
PubMed1984

Simultaneous isolation of two platelet membrane fractions: biochemical, immunological and functional characterization.

Simultaneous isolation of two platelet membrane subfractions was achieved by centrifugation on 40% sucrose from a 100.000 g crude membrane fraction. Characterization of both types of membranes was carried out by different biochemical and immunological markers. Using a surface label, 3H Concanavalin A (3HCon A), a marker enzyme, phosphodiesterase, and lipid analysis, one of the fraction has been identified as external or plasma membranes, the other consists of intracellular membranes. Further two specific antibodies directed against external membrane antigens (LeKa and IgG L) react almost exclusively with the external membranes. Finally both kinds of membranes were able to uptake calcium but the affinity for this cation was higher for the internal than for the external membranes. This suggests that both membranes are implicated in the regulation of the cytoplasmic calcium concentration and that the internal membranes (dense tubular system) play the major part in this regulation.

Antigens↗
PubMed1984

The effect of low dose oral contraceptives on the initial immune response to infection.

The use of oral contraceptives have been shown to produce alterations in the normal physiology of many organ systems. However, little is known as to the effect of oral contraceptives on the immune response. The current study was undertaken to determine if women on low dose oral contraceptives show alterations in their initial immune response. An in vitro assay stimulating human peripheral lymphocytes was used. No differences were found in the proliferative immune response of B- or T-cells in women taking low dose oral contraceptives as compared to controls. This study suggests that the initial immune response of lymphocytes in patients on low dose oral contraceptives remains intact.

Antibody Formation↗
PubMed1984

Effects of chlorprothixene, haloperidol, and trifluoperazine on the delayed-matching-to-sample performance of pigeons.

The effects of chlorprothixene (4,6,8, and 10 mg/kg), haloperidol (0.13, 0.25, 0.38, and 0.5 mg/kg), and trifluoperazine (0.5, 1,2, and 3 mg/kg) were examined in pigeons responding under a delayed-matching-to-sample procedure in which delays of 0.5-, 1-, 2-, 4-, and 8-sec duration were arranged during each experimental session. Both chlorprothixene and trifluoperazine typically reduced accuracy (percent correct responses); the magnitude of this effect was generally largest at the longest delay values. Chlorprothixene was associated with an increased rate of responding to the sample stimulus in two of three subjects, whereas trifluoperazine almost always decreased response rate. Haloperidol at high doses decreased response rate, but failed to consistently impair accuracy at any dose or delay value.

Animals↗
PubMed1984

The role of opioid peptides in the hormonal responses to acute exercise in man.

Opioid involvement in the physiological and hormonal responses to acute exercise was investigated in six normal male subjects. Each was exercised to 40% (mild exercise) and 80% (severe exercise) of his previously determined maximal oxygen consumption on two occasions, with and without an infusion of high-dose naloxone. The exercise task was a bicycle ergometer; mild and severe exercise were performed for 20 min each, followed by a recovery period. Exercise produced the expected increases in heart rate, blood pressure, ventilation, tidal volume, respiratory rate, oxygen consumption and carbon dioxide production. After severe exercise, naloxone infusion increased ventilation from 94.8 +/- 4.9 litres/min to 105.7 +/- 5.0 litres/min (P less than 0.05), but had no effect on any of the other physiological variables. Exercise-induced changes in several hormones and metabolites were noted, including elevations in circulating lactate, growth hormone (GH), prolactin, cortisol, luteinizing hormone (LH), follicle stimulating hormone (FSH), adrenaline noradrenaline, plasma renin activity (PRA) and aldosterone. There was no change in plasma met-enkephalin. Naloxone infusion produced the expected increases in LH and cortisol, but also significantly enhanced the elevations in prolactin, adrenaline, noradrenaline, plasma renin activity and aldosterone (P less than 0.05). Psychological questionnaires revealed minor mood changes after exercise, but no evidence was found for the suggested 'high' or euphoria of exercise. Effort was perceived as greater during the naloxone infusion than the saline infusion in every subject.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

The evolution of beta-adrenergic dysfunction during the induction of canine cobalt cardiomyopathy.

This study was designed to investigate the changes in the beta adrenergic system during the induction of cobalt cardiomyopathy in dogs. Cobalt sulphate, at a dose of 5 mg X kg-1 X day-1 was administered intravenously with a low protein, low thiamine diet to 13 dogs. The percentage change of the left ventricular minor axis with systole by echocardiogram (% delta D) and dP/dtmax were used to monitor left ventricular function. Noradrenaline (NA) was measured in 24 h urine samples. Left ventricular (LV) free wall biopsies were assayed for noradrenaline (LV-NA), cyclic AMP, cyclic GMP and dopamine beta hydroxylase (LV-DBH). Lymphocytes were assayed for beta-receptor density. All dogs were studied at baseline and seven were studied after a midpoint cumulative dose of 60 to 90 mg X kg-1 of cobalt; the remaining six dogs were studied when they were in heart failure and had received more than 110 mg X kg-1. During the induction of heart failure the heart rate rose from 112 +/- 6 (means +/- SE) at baseline to 154 +/- 9 at the midpoint and 153 +/- 9 (both P less than 0.05) at the final measurement while the % delta D fell from 35 +/- 2% to 31 +/- 3% and 23 +/- 2% (P less than 0.05) and dP/dt fell from 333 +/- 40 kPa X s-1 at baseline to 254 +/- 46 kPa X s-1 (P less than 0.05) and 207 +/- 33 kPa X s-1 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Phosphate/hexose 6-phosphate antiport in Streptococcus lactis.

After growth in appropriate media, resting cells of Streptococcus lactis 7962 showed a rapid exchange between external and internal pools of inorganic phosphate. This exchange was not found in other strains of S. lactis (ML3, 133, or K1) or in Streptococcus faecalis. Phosphate exchange in S. lactis 7962 did not require other anions or cations in the assay medium, nor was phosphate influx affected by the membrane potential and pH gradient formed during glycolysis. Thus, the exchange reaction was independent of known ionic drivers (H+, Na+, OH-, etc.). Experiments testing inhibitions of phosphate entry suggested that alternative substrates for exchange included arsenate, as well as the 6-phosphates of glucose, 2-deoxyglucose, fructose, mannose, or glucosamine, and direct studies with 2-deoxyglucose 6-phosphate verified that resting cells could accumulate this sugar phosphate to levels expected for exchange with internal phosphate. Two other observations supported the idea of an exchange between phosphate and sugar phosphate. First, early addition of the heterologous substrate blocked entry of the test compound, whereas later addition caused efflux of preaccumulated material. Second, expression of phosphate exchange and 2-deoxyglucose 6-phosphate transport varied in parallel. Both activities were found at high levels after growth in medium supplemented with rhamnose or arabinose, at intermediate levels with addition of galactose, and at low levels after growth with glucose, fructose, or mannose. We conclude that these findings describe a novel anion antiporter that mediates the exchange of phosphate (arsenate) and sugar 6-phosphates.

Anions↗
PubMed1984

Hospital safeguards capital program through private sector partnership.

As access to capital tightens, more hospitals are exploring the benefits of partnerships with private companies. A California hospital, burdened by the long-term debt it incurred for a medical office building, worked together with its medical staff and an outside real estate developer. By selling the building to the developer, not only was the hospital able to finance a much-needed expansion and reconstruction project, but the hospital's medical staff had an opportunity to become limited partners in the ownership of the building.

California↗