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Biomedical subjects

M S Hall

Publications and source records attributed to M S Hall.

At least 19 recordsLinked to original sources
PubMed1994

Effect of periodate-oxidized ATP and other nucleotides on firefly luciferase.

Addition of periodate-oxidized ATP (oATP) to firefly luciferase-containing reaction mixtures enhanced light production when the reaction mixture contained > approximately 8 microM ATP. The time course of light production was changed from a flash pattern to a constant light output during incubations of < approximately 10 min. During longer incubation, firefly luciferase was inactivated in a concentration-dependent fashion by oATP. Firefly luciferase has two different time courses of light production that depend on ATP concentration (DeLuca and McElroy, Biochem. Biophys. Res. Commun., 123, 764, 1984). The enhancement of light production occurred only when higher ATP concentrations (> 8 microM) were used. There is little effect of oATP on firefly luciferase activity at low ATP concentrations (< 2 microM) which gave steady production of light. ATP did not antagonize the inactivation of firefly luciferase by oATP. When the oATP was chemically reduced with sodium borohydride (giving or ATP), there was no inactivation of firefly luciferase on incubation. When or ATP was used in a short incubation the enhancement of light production and time course change were the same as those observed with oATP. The corresponding AMP and adenosine compounds (o and or) were slightly inhibitory to firefly luciferase activity. ADP was without effect but both oADP and or ADP enhanced light production. Of these periodate-oxidized ADP, AMP, and adenosine derivatives only oADP inactivated firefly luciferase. The activating effect can be explained by a change in the conformation of the enzyme-product complex so that the product is released faster. In addition there is an inactivation of the enzyme by certain periodate-oxidized nucleotides during longer incubations.

Adenine Nucleotides↗
PubMed1992

Enhancement of firefly luciferase activity by cytidine nucleotides.

The temporal pattern of light production by firefly luciferase depends on the ATP concentration. With low concentrations of ATP a constant production of light occurred while at high concentrations of ATP (greater than 10 microM) there was a flash of light followed by a decline in light production. This time course of light production with high ATP concentrations was changed from the flash pattern to a pattern with a constant production of light by several cytidine nucleotides. CTP, CDP, dCTP, dCDP, dideoxyCTP, periodate-oxidized CTP and CDP, and the etheno derivatives of CTP and CDP produced that change. CMP, cytidine, CDP-glycerol, CDP-glucose, CDP-ethanolamine, and benzoylbenzoylCTP either were inhibitory to firefly luciferase or were not effective in changing the flash time course. Coenzyme A and related compounds also changed the time course of light production. The changes in time course produced by either cytidine nucleotides or CoA were inhibited by desulfoCoA. These compounds apparently enhanced light production by promoting the dissociation of the inhibitory product, oxidized luciferin, from the enzyme. When the activating compounds were used with high concentrations of ATP, the sensitivity of assay for firefly luciferase was increased. This increased sensitivity is important when using the firefly luciferase gene as a reporter.

Adenine Nucleotides↗
PubMed1992

Comparison of properties of commercially available crystalline native and recombinant firefly luciferases.

Commercially available crystalline native and recombinant firefly luciferases were compared. The two types of luciferase had indistinguishable responses to variation in ATP and luciferin concentrations and to omission of reaction components. The time courses of light production, the responses to nucleotide analogues, and the stability of the enzymes under several storage conditions were identical. The native enzyme had a slightly greater specific activity and was more sensitive to trypsin degradation. These differences are probably attributable to differences in conformation.

Adenosine Triphosphate↗
PubMed1992

Peer support group for adolescents with chronic illness.

This study assessed the effects of a monthly peer support group for adolescents with cancer and other hematological diseases. These adolescents shared activities and experiences with nondisabled high school students. At the group's conclusion, the adolescents reported that the group helped them cope with their illness and improved the quality of their daily lives. Nondisabled students reported that the group favorably affected their attitudes about, and intended behavior toward, peers with chronic illnesses. These results suggest that such groups can provide important benefits for individuals with chronic illnesses as well as for their nondisabled peers.

Adaptation, Psychological↗
PubMed1992

General practitioners' confidence in diagnosing and managing eye conditions: a survey in south Devon.

In order to open dialogue aimed at increasing eye care in general practice and reduce waiting times for ophthalmic outpatient appointments general practitioners in the Torbay health district were asked about their levels of confidence in ophthalmology as a subject, and in the diagnosis and management of specific eye conditions. They were also asked about ophthalmic equipment available to them, their management policies for 34 specific eye conditions, and their perceived need for further training in this subject. A total of 75% of the general practitioners responded to the questionnaire. Despite more than half of the general practitioners indicating that they did not feel confident with ophthalmology generally, most expressed confidence in diagnosing and managing common eye conditions. Basic equipment for examining the eye was available to most doctors. Referral policies varied considerably, and these have resource implications. Seventy eight per cent of respondents were prepared to take on more eye care in general practice, and over 80% of general practitioners requested informal teaching sessions in ophthalmology. Support must be forthcoming if general practitioners are to provide eye care in general practice.

Clinical Competence↗
PubMed1991

The Exeter Diabetic Project: an acceptable district-wide education programme for general practitioners.

The Health District is a logical administrative unit for planning health services, and therefore the feasibility of delivering education for general practitioners across one such area was studied. By providing a suitable educational programme at convenient locations, it was possible to involve 89% out of 180 principals in General Practice in the Exeter Health District. Two-thirds of these general practitioners attended educational sessions away from the District Postgraduate Centre. In a questionnaire answered by 81% of the involved general practitioners, 98% acknowledged responsibility for managing their diabetic patients, but 76% admitted to inadequate skills in retinal assessment. In a follow-up postal questionnaire answered by 64% of general practitioners involved in the project, 74% found that they learnt from the retinopathy screening clinic and 100% found the sessions on eye disease helpful. The education programme was designed to link with a District-wide retinopathy screening initiative.

Demography↗
PubMed1990

Evaluation of virus neutralization antibody levels in diabetic mutant mice.

Experiments were designed to determine whether genetic predisposition to diabetes or overt diabetes in the identical genotype had an effect on the level of neutralization antibodies to coxsackievirus B4 (CB4). Quantitation of neutralization antibody (NT) levels against CB4 was performed using both the 50% endpoint procedure and the multivariate Wilcoxon rank sum test. The results of these experiments demonstrate that the use of the multivariate procedure for the analysis of neutralization antibody levels provides both quantitative and qualitative information not evident when only the classical 50% end point procedure is used. Moreover, when comparison on antibody levels between different groups is being considered, the power of the comparison is markedly greater using the multivariate Wilcoxon rank sum test results. The present report provide an illustration of the difference in the qualitative and quantitative information obtained by the end-point procedure and the more comprehensive multivariate procedure for the analysis of neutralization antibody levels in diabetic mutant mice infected with coxsackievirus B4.

Animals↗
PubMed1987

Renal metabolism of amino acids in vivo: studies on serine and glycine fluxes.

The pathway of serine synthesis by the rat kidney has been investigated in vivo by measuring the net flux in the presence and absence of specific inhibitors of the glycine cleavage system, phosphoenol-pyruvate carboxykinase and gamma-glutamyltranspeptidase. In normal animals serine release was 705 +/- 187 nmol X min-1 X animal-1, whereas glycine uptake was only 28% of this value. Inhibition of the glycine cleavage system (cysteamine infusion) resulted in a reversal of glycine flux with no change in serine production. In similar experiments with mercaptopicolinate serine release was decreased by 55% with no change in glycine removal. AT-125, a potent inhibitor of gamma-glutamyltranspeptidase, had no effect on renal serine and glycine fluxes. In chronically acidotic rats serine synthesis was unchanged, but there were significant increases in the uptake of glutamine (fourfold) and glycine (2.5-fold). Infusion of cysteamine into these animals caused a 50% decrease in serine release with a significant reversal of the glycine flux. Infusion of mercaptopicolinate had effects similar to those observed in normal animals. These results show that renal serine synthesis can occur by both the phosphorylated-intermediate pathway and serine hydroxymethyltransferase in vivo. Furthermore, they demonstrate that glycine can contribute significantly to ammoniagenesis during acidosis.

Amino Acids↗