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Biomedical subjects

R Heath

Publications and source records attributed to R Heath.

53 records · Page 3Linked to original sources
PubMed1984

The mechanism of inhibition of ureogenesis by acidosis.

In perfused rat liver a decrease of cytosol pH, determined with pH-sensitive microelectrodes, from 7.2 to 6.85 is associated with a 50% fall in ureogenesis from ammonium chloride. In isolated rat hepatocytes the fall in ureogenesis due to acidosis is associated with decrease in the mitochondrial and cytosolic concentration of citrulline. Limitation of carbamoyl phosphate synthesis and thus citrulline supply could be responsible for the inhibition of ureogenesis observed.

Acidosis↗
PubMed1984

Hormonal control of carbonic anhydrase III.

Using radioimmunoassay, the concentration of carbonic anhydrase III (CA III) in the livers of adult male rats was found to be approximately 30 times greater than that observed in mature females. Castration of male rats led to a marked reduction in liver CA III concentrations that could be partially restored to control levels by testosterone replacement. Administration of testosterone to ovariectomized female rats induced about a 5-fold increase in liver CA III concentration. Immunoprecipitational analysis of the products of liver mRNA translation in vitro with antiserum specific for CA III showed that hormonal control of the levels of CA III in rat liver is mediated by changes in the amount of translatable CA III mRNA. Marked changes in liver CA III concentrations were also observed in developing and aging male rats. Different control mechanisms appear to operate in mouse and man.

Aging↗
PubMed1984

Plasma amino acids of the mid-trimester human fetus.

The amino acid concentrations in umbilical cord plasma taken at fetoscopy were measured from 12 fetuses between 18 and 29 weeks gestation. Concurrent maternal plasma levels were measured. Fetal plasma showed consistently higher concentrations of plasma amino acids with the ratios varying between 1.1:1 and 3:1 and the difference always reached statistical significance. It is suggested that these results reflect the in vivo situation of the mid-trimester human fetus.

Amino Acids↗
PubMed1983

Carbonic anhydrase III in Duchenne muscular dystrophy.

Plasma carbonic anhydrase III (CAIII) levels determined by radioimmunoassay have been compared, in detail, with creatine kinase (CK) as indices of Duchenne muscular dystrophy (DMD). CAIII levels were markedly elevated in all patients but variability of levels in a number of individual patients was higher than CK.

Adolescent↗
PubMed1983

Induction and repression of the major phenobarbital-induced cytochrome P-450 measured by radioimmunoassay.

Two independent radioimmunoassay techniques for the major phenobarbital-inducible cytochrome P-450 (PB P-450) of rat liver microsomal membranes are described. The first technique employs as the source of radiolabelled antigen the products of translation in vitro labelled with [35S]methionine. The second technique employs purified antigen labelled with 125I and is quicker, less expensive and more precise. Both assays are highly specific for PB P-450 and can detect quantities of this variant as small as 1 ng. This is several orders of magnitude more sensitive than any method described previously for the quantification of cytochromes P-450, and consequently the technique is particularly well suited for the quantification of so-called constitutive cytochrome P-450 variants that are present in very low amounts. The results of the radioimmunoassays demonstrate that the apparent 2.6-fold induction of total cytochromes P-450 after phenobarbital treatment is due to a 43-fold increase in Pb P-450. Although beta-naphthoflavone increases the total content of cytochrome P-450 of microsomal membranes 1.4-fold, it actually causes a 55% decrease in the amount of PB P-450. Thus different xenobiotics can have differential effects on the expression of the genes for specific cytochrome P-450 variants.

Animals↗
PubMed1983

Carbonic anhydrase III in neuromuscular disorders.

Plasma carbonic anhydrase III (CAIII) and creatine kinase (CK) were measured in 44 patients with a variety of neuromuscular disorders. Markedly elevated CK levels were associated with similarly increased levels of CAIII. In 9 patients, only the CAIII was elevated, but in 2 patients only the CK was raised. The determination of plasma CAIII is thus an important index of muscle disorder and is probably more sensitive than CK.

Adolescent↗
PubMed1983

Benign X-linked myopathy with acanthocytes (McLeod syndrome). Its relationship to X-linked muscular dystrophy.

Two healthy men with McLeod syndrome, a rare X-linked recessive phenotype characterized by acanthocytosis and weakened red blood cell antigenicity in the Kell blood group system, have been investigated. Both men showed raised blood creatine kinase levels, with myopathic EMG abnormalities. Biopsies of the quadriceps muscle showed the features of an active myopathy although there was no clinical evidence of muscular abnormality. The combination of the association of membrane abnormalities in red blood cells and a myopathy in both McLeod phenotype and Duchenne muscular dystrophy suggests that these syndromes may be due to related genetic abnormalities. The genetic locus for McLeod phenotype is situated near the end of the short arm of the X chromosome. The locus for Duchenne muscular dystrophy is unknown but it has been postulated that it is also situated on the short arm of the X chromosome at Xp 21. The occurrence of a subclinical X-linked myopathy with acanthocytosis (McLeod phenotype) thus raises the possibility of a new approach to genetic investigations in Duchenne muscular dystrophy, and in the related milder forms of this disease.

Acanthocytes↗
PubMed1982

Radioimmunoassay of human muscle carbonic anhydrase III in dystrophic states.

A radioimmunoassay for the human isozyme carbonic anhydrase III (CAIII) has been developed. The assay can detect levels as low as 4 microgram/l of sample. Plasma CAIII levels in patients suffering from Duchenne muscular dystrophy were found to be up to 39 times greater than levels in a control group. Urine CAIII levels in patients suffering from Duchenne muscular dystrophy were not significantly different from the levels found in urine from normal adults. Measurement of plasma CAIII levels may be useful in prenatal diagnosis of Duchenne muscular dystrophy, and in investigation of adult skeletal muscle disease.

Animals↗
PubMed1982

The effects of contextual variations on attitudes toward the elderly.

This study examined how attitudes about the elderly are influenced by the procedural context in which attitude expression is assessed. The Tuckman-Lorge Attitudes Toward Old People Questionnaire was modified so that all items reflected evaluative attitude statements; then it was administered to 263 adults in two judgmental contexts. One group was induced to make comparative judgments by rating how much the Tuckman-Lorge items described "old" people and "young" people, whereas a second group made isolated judgments by rating the items for "old" people only. Analyses revealed that adults in the comparative context expressed more extreme negative attitudes about the elderly than adults in the isolated context. Correlational analyses revealed consistent but generally weak relationships between attitudes toward the elderly and various demographic characteristics. The findings indicate that conflicting results from studies of attitudes about the elderly may be partially explained by procedural differences in the kind of judgmental context used.

Adolescent↗
PubMedDate not supplied

Relationship of removable partial denture use to root caries in an older population.

The pattern and severity of root caries in a selected older population, living in the community and attending a general dental practice in Bexhill, East Sussex, England, is reported. A total of 146 patients were examined to determine the relationship among removable partial dentures, their design, and root caries. Of those patients, 57% wore removable dentures and had a higher prevalence of exposed root surfaces and root caries, particularly on abutment teeth. In addition, root caries lesions on abutment surfaces were found to be larger and more active than those on nonabutment surfaces.

Aged↗