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Biomedical subjects

A D Evans

Publications and source records attributed to A D Evans.

13 recordsLinked to original sources
PubMed2000

Identification of a polymorphic ryanodine receptor gene from Heliothis virescens (Lepidoptera: noctuidae).

cDNAs encoding the C-terminal 1172 amino acids of a ryanodine receptor (RyR) from the lepidopteran pest Heliothis virescens (Hv-RyR) have been cloned and characterised. Sequence comparisons, organisational studies on corresponding genomic regions and a genetic segregation analysis provide evidence for two polymorphic alleles of the Hv-RyR locus. Comparison of the Hv-RyR C-terminal amino acid sequence with equivalent regions of other RyRs reveals a high level of overall amino acid homology (74% identity with D. melanogaster and between 47.9 and 50.1% with vertebrate isoforms). Homologies are however not uniformly distributed, though regions of high and low similarity are consistent with patterns in other RyR isoforms. The structural similarity of Hv-RyR with other RyRs is also indicated by comparison of hydropathy profiles and other previously described functional domains. Such results are consistent with this region of Hv-RyR containing the Ca(2+) channel itself and being intimately involved in RyR regulation. Potential uses of the cDNAs described in the discovery and development of novel ryanodine like insecticides are discussed.

Alleles↗
PubMed1995

Chloride binding in the stroma of cultured human corneas.

In the ox cornea, more than half of the non-diffusible, matrix negative charge is derived from the binding of free chloride ions. Because the magnitude of the net matrix charge is the dominant factor which determines the degree of stromal swelling, we investigated whether this phenomenon, stromal chloride binding, also occurs in human corneal stroma. Intrastromal ion concentrations were measured with radio-isotopes when human (outdated Eye Bank) corneas or (fresh) bovine corneas, physically clamped to maintain a constant hydration, were incubated in buffered 154 mM NaCl. The intrastromal chloride ion concentration was compared to the normalized concentrations of trace quantities of radio-labelled acetate and lactate ions. For human corneas, the intrastromal chloride ion concentration was found to be significantly higher (P < 0.001, t-test) than the normalized concentrations of both acetate and lactate ([Cl]i = 142.5 +/- 0.9 mM, (n = 9); [acetate]i = 131.2 +/- 1.2 mM, (n = 8); [lactate]i = 131.9 +/- 1.5 mM, (n = 5); all values are mean +/- S.E.M.). The sodium ion concentration was elevated ([Na]i = 176.0 +/- 1.8 mM, (n = 9)). These results demonstrate that chloride binding occurs to a significant extent in cultured human corneal stroma and suggest that chloride binding may be evident in the native human cornea.

Animals↗
PubMed1984

Sudden death in squash players.

A series of thirty sudden deaths (twenty-nine men, one woman) associated with squash playing is described. The subjects' mean age was 46.7 +/- SD 9.58 years (range 22-66). Necropsy results were available for twenty-seven subjects. Significant coronary heart disease (CHD) was found in twenty-three, valvular heart disease in three, and hypertrophic obstructive cardiomyopathy in one, and cardiac arrhythmia, in the absence of other pathology, was thought to have preceded death in two. One subject died from intracerebral haemorrhage. Twenty-two had reported prodromal symptoms, and of those with CHD, sixteen had had at least one identifiable CHD risk factor. Twelve subjects had been known by their family physician to have a medical disorder related to the cardiovascular system.

Adult↗
PubMed1982

Q fever in an urban area.

In the summer of 1981 29 patients living in Gwent, South Wales, had Q fever; 20 were diagnosed by routine clinical and laboratory services and 9 were discovered by active case-finding. The date of onset of symptoms spanned a 2-month period. The peak incidence was at the end of June. A case-control study showed an association with one area on the outskirts of Newport. Most patients had no direct contact with farms of farm animals and a common source of infection could not be identified. The most likely explanation of the outbreak was that farm vehicles had disseminated contaminated straw, manure, or dust in the area of Newport adjacent to farmland.

Adolescent↗
PubMed1975

Influenza vaccination and mortality from bronchopneumonia in the elderly.

In a three-year influenza vaccination programme carried out among elderly patients these were found to have a lower haemagglutination-inhibiting antibody level and a poorer serological response to vaccination than younger persons in the same city. Although there was little difference in overall respiratory illness between the vaccinated and unvaccinated groups until the third year of observation, those who received vaccine showed a substantially smaller incidence of bronchopneumonia and a significantly lower mortality than those not so protected. The observations are believed to justify the giving of influenza vaccine in this age-group.

Age Factors↗