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Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 865 records · Page 48Linked to original sources
PubMed1975

Isolation and chemical characterization of collagen in bovine pulmonary tissues.

1. The contents of the fibrous proteins collagen and elastin in the pleural and parenchymal regions of bovine lungs were determined. The collagen content was approx. 70% (g/100g of salt-extracted defatted powder) in each tissue, and the elastin content was 28% in pleura and 13.5% in parenchyma. 2. Purification of the insoluble collagen from the pleura and parenchyma of bovine lungs by various methods was attempted. The collagen fractions isolated after incubation of the pulmonary tissues with the proteolytic enzymes collagenase ("collagenase-soluble" fraction) or pancreatic elastase ("elastase-insoluble" fraction) each contained approx. 87% of the total collagen initially present. 3. Both collagen fractions were chemically analysed for their amino acid and carbohydrate contents and were found to be similar to those of the intact interstitial collagens isolated from skin, bone and tendon. 4. The contents of the two aldimine cross-linking compounds, dehydrohydroxylysinonorleucine and dehydrodihydroxylysinonorleucine, were determined in the bovine pulmonary collagen fractions, and were found to decrease with increasing age of the animals, and were similar to the values found in intact collagens from bone and tendon.

Amino Acids↗
PubMed1975

Isolation and characterization of acidic structural glycoproteins in pulmonary tissues.

1. Extraction of the pleural and parenchymal regions of bovine lungs with salt and organic solvents gave powders that contained glycoproteins in addition to collagen and elastin. The contents of these glycoproteins (g/100 of powder) was 4% in pleura and 15.5% in parenchyma. 2. Attempts were made to purify these glycoproteins fromboth tissues by various methods. 3. Both tissues contained heterogeneous mixtures that were similar solubilities, had similar amino acid and carbohydrate compostions. 4. The compostions of the pulmonary glycoproteins resembled those isolated from other connective tissues by other workers.

Amino Acids↗
PubMed1975

A method for estimating the prevalence of tuberculosis infection.

The prevalence of tuberculous infection in a population is generally estimated from calculating the proportion of tested individuals who react with at least 10 mm of induration to 5 TU of PPD-S tuberculin. Reactions due to infection with atypical mycobacteria, however, may cause the prevalence to be overestimated. This paper is concerned with an alternative method of estimating the prevalence of infection with Mycobacterium tuberculosis. The method utilizes population distributions of reaction size by dividing study populations into two groups--individuals with and without known exposure to tuberculosis. The mathematical model developed here removes the effect of atypical infections and provides a truer picture of tuberculous infection. Data from a Navy recruit population demonstrate the use of the model with the result that among recruits with no known exposure to tuberculosis, the estimated prevalence is reduced by about one-half. Among recuits with known exposure to tuberculosis, there is essentially no difference between the two methods. Important advantages in using this method are that probabilities of true infection by induration size are generated, and that itis less sensitive to variations caused by differences in reading techniques and in tuberculin potencies. Furthermore, it is applicable to other diseases if the underlying assumptions are met.

Epidemiologic Methods↗
PubMed1975

Inhibition of intestinal amino acid absorption by unconjugated bile salt in vivo.

The intestinal absorption of five amino acids studied (L-lysine, L-glycine, L-leucine and L-tyrosine) and one dipeptide (glycylglycine) was significantly inhibited by the deconjugated bile salt, sodium deoxycholate, in rats in vivo. It is suggested that inhibition of absorption of amino acids and dipeptides by unconjugated bile salts may contribute to hypoproteinaemia in patients with the contaminated small-bowel syndrome.

Amino Acids↗
PubMed1975

Effect of stasis on intestinal enzyme activities.

Activities of the small intestinal mucosal enzymes lactase, sucrase, maltase, alkaline phosphatase and N-acetyl-beta-glucosaminidase were studied in rats with surgically-induced upper intestinal stasis and in control animals. The first four are brush border enzymes, the latter a lysosomal enzyme. There was a reduction in the activities of all enzymes in the operated animals. The change lining was significant and most marked in mucosa the blind loop and gut distal to it; areas in which there is gross bacterial overgrowth and excessive levels of intraluminal deconjugated bile salts. The significance of these findings in relation to malabsorption consequent on bacterial contamination of the upper gut is uncertain and requires further study.

Acetylglucosaminidase↗
PubMed1975

Deoxycholate depresses small-intestinal enzyme activity.

Feeding sodium deoxycholate orally to rats for four days caused depression of the activity of the small intestinal enzymes lactase, sucrase, maltase, alkaline phosphatase, and N-acetyl-beta-glucosaminidase. The first four are brush border enzymes, the last a lysosomal enzyme. Alkaline phosphatase activity recovered very rapidly and rebounded to above the normal level within 24 hours. The activity of the three disaccharidases returned to normal within seven days while no recovery was observed within 96 hours of the activity of the lysosomal enzyme, N-acetyl-beta-glucosaminidase, after removing the bile salt from the diet.

Administration, Oral↗
PubMed1975

Do brine shrimp diagnose cystic fibrosis?

The nauplii of the brine shrimp Artemia salina are dependent upon the function of their salt gland to maintain osmotic pressure within narrow limits. A number of drugs interfere with this function and are lethal to the nauplii. Saliva and serum from normal persons, patients with cystic fibrosis, and obligate heterozygotes were tested for lethal effect against brine shrimp nauplii. At salt concentrations between 100 mM and 2.5 no difference was found among the phenotypes. At lower concentrations a difference was noted occasionally between some normal subjects and some individuals carrying one or two genes for cystic fibrosis. Data from an independent series of experiments indicate that the naupliar deaths result from distorted ratios of Na+/K+ and not from a specific gene product. No difference was noted in the O2 uptake of nauplii treated with saliva or serum obtained from normal subjects, patients with cystic fibrosis, or obligate heterozygotes.

Animals↗
PubMed1975

Metabolism and urinary excretion of chlormethiazole in humans.

1. Chlormethiazole and five of its metabolites excreted in urine in man have been investigated by g.l.c.-mass spectrometry. 2. Four metabolites have been identified by comparison with authentic compounds as 5-acetyl-4-methylthiazole, 5-(1-hydroxyethyl)-4-methylthiazole, 5-(2-hydroxyethyl)-4-methylthiazole and 4-methyl-5-thiazoleacetic acid; 4-methyl-5-thiazoleacetaldehyde is proposed for the other metabolite. 3. The amounts of chlormethiazole and its identified metabolites excreted in urine have been quantitatively determined after a single oral dose in three healthy adults. Approximately 16% of the dose was excreted as chlormethiazole, 5-acetyl-4-methylthiazole, 5-(1-hydroxyethyx)-4-methylthiazole and 4-methyl-5-thiazoleacetic acid.

Adult↗
PubMed1975

[Evaluation of the parietal factor interfering in the measurement of cardiac output by external detection with the aid of 99mTc labelled red cells (author's transl)].

The results of a radioisotopic exploration are not independant of the physical characteristics of the tracer used. Thus in the measurement of cardiac output index by external detection, the substitution of 131I fastened on the human serum albumine by 99mTc fastened on red cells introduces a systematic average error of +20% whose origin is double. Because of the plasma or red cell kind of the tracer, the average error done on the volume is, in 130 measurements, 26% whereas that which results from the difference of photon energy is -6%. Only this last error affects the measurement of the cardiac output and, by that time, it is demonstrated that a direct determination of the cardiac output index by STEWART-HAMILTON'S relation is impossible.

Cardiac Output↗
PubMed1975

Studies of thymus-derived and bone marrow-derived lymphocytes in renal transplant patients.

Serial studies of levels and responsiveness of T and B lymphocytes were performed in human renal allograft recipients. Patients given prednisolone-azathioprine immunosuppression had only mild falls in levels and responsiveness of T cells. Patients given a quality controlled ATG preparation had marked and relatively selective falls in levels of T cells associated with a marked fall in T cell responsiveness as measured by PHA and Con-A responsiveness. In vivo correlates of this severe T cell deficiency suggest that T lymphocytes are central to acute allograft rejection and that acute severe T cell deficiency is not associated with risk of infectious complications above and beyond those seen in patients suppressed with prednisone-azathioprine alone. These studies suggest that ATG, produced under quality control conditions and having rather selective anti-T cell activity, is a useful adjunctive immunosuppressive agent for human renal transplantation.

Antilymphocyte Serum↗
PubMed1975

Anticestode quinolinehydrazones.

One hundred and seven 4-quinolinehydrazones were synthesized and tested in vivo against the tapeworm Hymenolepis nana. Twenty-five derivatives showed significant cestocidal activity; structure-activity correlations were performed using Free-Wilson methodology. Two compounds, 2,6-dimethyl-4-[(3-pyridinylmethylene)hydrazino]quinoline and 2,6-dimethyl-4-[2p][(6-methyl)pyridinylmethylene]hydrazino)quinoline, predicted to be maximally active, effected 100% reduction of H. nana in mice at 200 mg/kg, p.o.

Animals↗
PubMed1975

[Estimate of coronary blood flow by simple fixation measurement of 86Rb on the cardiac muscle (author's transl)].

The method for measuring coronary blood flow, which is described here, is based on the estimate, by external detection, of the quantity of 86Rb fastened on the cardiac muscle about ten minutes after the injection. The discussion which follows after this report, shows that the use of such a late time for the measurements does not contradict the fondamental hypothesis but allows to work in perfect technical conditions. The results obtained,widely superposable to those which have been published until to-day, prove a posteriori the availability of the method.

Coronary Circulation↗
PubMed1975

Pharmacological study of a new substance, mecinarone.

Mecinarone, a benzofuranic chalcone, shows considerable vasodilating activity on the peripheral and cerebral circulation. The intramuscular irrigation is thus improved and the cerebral blood supply increased. This vasodilating activity is accompanied by only a slight drop in the systemic arterial pressure and occurs without cardiac depression. Mecinarone has also antibradykinin, antiserotonin and antiaggregation properties which added to the vasodilating activity, greatly increase its pharmacological interest.

Administration, Oral↗