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Biomedical subjects

J R Fisher

Publications and source records attributed to J R Fisher.

At least 19 recordsLinked to original sources
PubMed1988

Efficacy of water vapor-saturated air in the treatment of exercise-induced pulmonary hemorrhage in Thoroughbred racehorses.

The efficacy of water vapor-saturated air as a treatment for horses with exercise-induced pulmonary hemorrhage (EIPH) was studied. Horses selected for study (n = 14) had grade 1 or greater hemorrhage in the trachea after a minimum of 4 breezes between 0.8 and 1 km, as determined by endoscopy. Nine horses were treated with water vapor-saturated air; 5 horses were not treated. When the mean and maximal EIPH scores from the pretreatment period were compared with the mean and maximal EIPH scores from the treatment period in both treated and nontreated groups, there was no significant difference between groups. There was a suggestion of a linear relationship between exercise speed and the mean EIPH score of the first 4 breezes in all 14 horses.

Animals↗
PubMed1985

Transillumination in breast cancer detection: screening failures and potential.

This prospective study of 1265 women referred to a multimodality breast diagnostic center compares the sensitivity for breast cancer detection of state-of-the-art transillumination light scanning and film-screen mammography. Of 33 biopsy-proven cancers, transillumination light scanning detected 58%, while mammography detected 97% of the cancers. Light scanning did detect 55% of the nonpalpable breast cancers, and 30% of those tumors smaller than 1 cm. Detection of breast cancer by light scanning was affected by breast size, but not architecture, and was directly related to tumor size. Although transillumination light scanning can detect some small curable breast cancers (smaller than 1 cm), it does not do so at a sensitivity adequate for screening. An example is illustrated in which light scanning detected an occult breast cancer before the development of recognizable mammographic changes.

Adult↗
PubMed1979

Synthesis and degradation of xanthine dehydrogenase in chick liver. In vivo and in vitro studies.

The present study describes the (xanthine:NAD+ oxidoreductase, EC 1.2.1.37) synthesis and degradation of chick liver xanthine dehydrogenase in vivo and in organ cultures. The results indicate that control of xanthine dehydrogenase activity is mediated by changes in the rate of enzyme synthesis, but that degradation rates are unaffected. The results also suggest that xanthine dehydrogenase synthesis occurs through a previously unreported intermediate. Detected in cultures of liver tissue, this intermediate apparently is not converted into an active enzyme. A model of synthesis and degradation for xanthine dehydrogenase proposes that the synthesis of the enzyme is proportional to messenger RNA and includes an inactive enzyme precursor and a second inactive intermediate prior to degradation. Integrated mathematical solutions describing the concentration of intermediates as a function of time can be found explicitly for simple models. The appendix to this paper extrapolates solutions for one-, two- and three-step models to generate a mathematical solution for an 'n'-step model containing 'n' intermediates. The rate constants in the solutions can be found experimentally.

Animals↗
PubMed1979

Necrotizing fasciitis. Importance of roentgenographic studies for soft-tissue gas.

Twenty-six patients with necrotizing fasciitis were treated during a nine-year period. Twenty-one (81%) had diabetes mellitus and 19 (73%) had gas in their soft tissues from nonclostridial infection. Although crepitation was found by physical examination in only five patients, roentgenographic examination of the involved site disclosed gas in every patient in whom it was subsequently found at surgery. Previous studies have not used roentgenography to search for soft-tissue gas. The 21 diabetic patients in our series had a mortality of 19%, the lowest yet reported. This suggested that roentgenographic study of cases with fasciitis permits earlier diagnosis and favorably affects outcome.

Adult↗
PubMed1977

Purification and properties of the adenosine deaminase from the midgut gland of a marine bivalved mollusc, Atrina spp.

1. The adenosine deaminase has an approximate molecular weight of 130,000-140,000 and the composition of two polypeptide units (mol. wt about 68,000) is suggested, by means of SDS disc electrophoresis. 2. Both the alpha (Vm/Km) and beta (Vm) parameters were varied with pH and temperature. RSS (relative substrate specificity) adenosine and deoxyadenosine values for alpha and beta were 1.2 and 1.1, respectively. 3. Adenine, 2'-, 3', 5'-AMP, 5'-deoxyAMP, ADP and ATP were not deaminated by the enzyme. 4. Inhibition by Mg2+ was found in reaction with adenosine at pH 8 but not with deoxyadenosine at the same pH. Mn2+, which did not affect the reaction rate at pH 4 and 5, showed competitive inhibitory effects at pH 6, 7 and 8.

Adenosine Deaminase↗
PubMed1977

Regulation of nitrogen catabolic enzymes in chick liver: effects of insulin.

Previous studies have shown that a group of nitrogen catabolic enzymes including xanthine dehydrogenase, purine nucleoside phosphorylase, and tyrosine aminotransferase are all increased in chick liver by dietary protein as well as single amino acids (e.g. methionine) and certain antimetabolites (e.g. hydrazine). A similar enzyme response pattern can be obtained with insulin. This hormone causes an enhanced rate of XDH synthesis and gives nonadditive results with protein, hydrazine and methionine. Furthermore, a vitamin B6 dependency was observed in responses to both high protein diets and insulin, all suggesting a common regulatory mechanism. In this system dietary protein and insulin may act similarly by increasing the availability of amino acids to the liver -- in one case by supplying amino acids through the diet and in the other by increasing amino acid uptake.

Animals↗
PubMed1976

Regulation of nitrogen catabolic enzymes in chick liver -- effects of amino acids.

It is well-known that in the chick, dietary protein increases the levels of several hepatic enzymes that are involved in nitrogen metabolism and excretion. However, the biochemical mechanism of this response is essentially unknown. The experiments presented in this paper show that the chick is responding to alpha-amino nitrogen and not to any specific amino acid. Furthermore, it is shown that this system responds to endogenous sources of nitrogen as well as dietary protein and that the xanthine dehydrogenase response involves regulation of enzyme synthesis without changing the rate of degradation.

Amino Acids↗