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Biomedical subjects

D McDonald

Publications and source records attributed to D McDonald.

At least 73 records · Page 4Linked to original sources
PubMed1995

Smokeless tobacco use: how it affects the performance of major league baseball players.

The authors examined the effect of smokeless tobacco use on the athletic performance of major league baseball players during the 1988 season. They evaluated performance records of 158 players on seven major league teams who played or pitched at least 10 games or innings during the 1988 season. ST use, they concluded, is not related to player performance in major league baseball but does place players at significantly increased risk for mucosal lesions and other oral pathology.

Adult↗
PubMed1995

Molecular characterization of endothelin receptors and the effect of insulin on their expression in retinal microvascular pericytes.

Microvascular pericytes contain predominantly endothelin A (ET(A))-like binding sites and also a smaller number of ETB binding sites. In this study we verified the expression of both receptors in these cells. We then examined the effect of insulin, a potent mediator of vasodilatation, on the expression of these receptors in pericytes by Northern hybridization. Northern hybridization studies showed that ET(A) mRNA levels were not influenced by exposure to insulin (1 x 10(-7) M). By contrast, ETB receptor mRNA, which was minimal under basal conditions, was significantly increased by 4 h after exposure to insulin.

Animals↗
PubMed1994

5-Formyltetrahydropteroylpolyglutamates are the major folate derivatives in Neurospora crassa conidiospores.

5-Formyltetrahydropteroylpolyglutamate (5-CHO-H4PteGlun) is the only reduced folate derivative that is stable to oxidation and alkaline pH. However, no metabolic role has been assigned to this folate derivative, and evidence for its existence in cells has been questioned. Recently, serine hydroxymethyltransferase was shown to catalyze the formation of 5-CHO-H4PteGlun from 5,10-methenyl-H4PteGlun (Stover, P., and Schirch, V. (1990) J. Biol. Chem. 265, 14227-14233). We have proposed that 5-CHO-H4PTeGlun may serve as a storage form of reduced folates and one-carbon groups in cells that are in a dormant stage. This hypothesis was tested by determining the levels of H4PteGlun derivatives in the mycelia and conidiospores of Neurospora crassa and a mutant strain that lacks cytosolic serine hydroxymethyltransferase. N. crassa serine hydroxymethyltransferase was purified to homogeneity and characterized with respect to kinetic constants, quaternary structure, stability, and reaction specificity. A new assay for determining the concentration of the polyglutamate forms of H4PteGlun derivatives was also developed. Using this assay, it was shown that 85% of the tetrahydropteroylpolyglutamates in conidiospores was 5-CHO-H4PteGlun. After adding the spores to growth media, the 5-CHO-H4PteGlun was reduced to less than 10% of the folate pool in 20 min. Mycelia had no detectable 5-CHO-H4PteGlun. Only 10-20% of the folate pool in conidiospores from the mutant strain lacking cytosolic serine hydroxymethyltransferase was in the form of 5-CHO-H4PteGlun.

Formyltetrahydrofolates↗
PubMed1994

Scalp-ear-nipple syndrome: additional manifestations.

Scalp-ear-nipple (SEN) syndrome is a rare, autosomal dominant condition that causes aplasia cutis congenita of the scalp, alteration of the shape of the external ear, and hypoplasia of the nipple. Women in a new family, the fifth to be described, had virtually complete aplasia of the breast and a small skin dimple without any pigmentation instead of a normal nipple, although other affected women had normal breast and nipple development. Dental changes included widely spaced or missing secondary teeth; the ears were cupped or folded and stood out from the head, axillary apocrine secretion and axillary hair growth were reduced; and finger nails were brittle. There was no generalized abnormality of sweating. Some patients had partial syndactyly of the 3rd and 4th fingers, and complete cutaneous syndactyly of the 2nd and 3rd toes. and 3rd toes.

Abnormalities, Multiple↗
PubMed1994

Organizational renewal and strategic planning: a winning combination.

Several approaches to organizational renewal have been described, but few are reported for health care institutions in Canada. In contrast, approaches to strategic planning in health care facilities have been well documented. From our experience over the past six years, the theory and practice of organizational renewal complement the focused activities of strategic planning. This combination can be an effective means to enhance organizational performance, employee commitment and a shared vision among the various stakeholders within the hospital and community. This article outlines the process and benefits that can accrue through such efforts. It demonstrates how the investment of organizational renewal strategies can produce sustainable, operational and strategic planning benefits for community hospitals.

Hospital Restructuring↗
PubMed1993

Australian deaths in custody, 1980-1989. 1. Relative risks of aborigines and non-aborigines.

OBJECTIVE: To assess the risks of death in police or prison custody in Australia for Aborigines and non-Aborigines. DESIGN, SETTING AND PARTICIPANTS: Retrospective collection and analysis of data about deaths occurring in police or prison custody in Australia in the 10-year period 1980-1989. RESULTS: For the period 1980-1989, Aboriginal and non-Aboriginal people in prison had risks of death similar to those of the total Australian population, but the risks of death in police custody for both Aborigines and non-Aborigines were between 10 and 20 times the risks of death experienced by the general population. Within each type of custody, there were no significant differences in the risks of death experienced by Aboriginal and non-Aboriginal people. CONCLUSION: Although some deaths in custody are inevitable, the very much higher risks of death in police custody for both Aborigines and non-Aborigines has implications for custodial authorities in terms of preventive and remedial action. Reduction of the excess of Aboriginal over non-Aboriginal deaths in police and prison custody relative to general population figures requires action to reduce the over-representation of Aboriginal people in custody and to improve the general well-being and health status of Aboriginal people in the community.

Adolescent↗
PubMed1993

Australian deaths in custody, 1980-1989. 2. Causes.

OBJECTIVE: To assess the causes of death for people in police or prison custody in Australia, with particular attention to the differences between Aboriginal and non-Aboriginal deaths. DESIGN, SETTING AND PARTICIPANTS: Retrospective collection and analysis of data about deaths occurring in police or prison custody in Australia in the 10-year period 1980-1989. RESULTS: In the period 1980-1989, 527 deaths are known to have occurred in police or prison custody. About half these deaths were due to self-harmful behaviour, including hanging. The next most frequent causes of death were diseases of the circulatory system, injuries and diseases of the respiratory system. CONCLUSION: The high number of deaths in custody resulting from self-harmful behaviour has important implications for the criminal justice and corrections systems. Minimisation of the number of people held in police and prison custody is important in preventing such deaths. Close attention needs to be paid to ensuring the safety of lock-ups and prisons and to the screening of people likely to be at risk of death from self-harmful behaviour. Custodial authorities have a clear responsibility to provide quality preventive and clinical health services to all people in custody. Special attention needs to be directed to the specific health needs of Aborigines, many of whom are at much greater health risk than are non-Aborigines.

Australia↗
PubMed1993

Factors affecting laterality of standard threshold shift in occupational hearing conservation programs.

Although noise-induced hearing loss is generally characterized as bilaterally symmetrical, 80% of audiometric shifts meeting Occupational Safety and Health Administration (OSHA) criteria were unilateral in a large industrial sample. The primary factor related to unilateral OSHA shifts was asymmetric baseline hearing level. Better ears at baseline audiogram were more likely to demonstrate OSHA shifts than poorer ears. When hearing levels were symmetric at baseline, left ears were more likely to demonstrate OSHA shifts. Although OSHA shifts were primarily unilateral, cumulative effects of noise exposure were judged to be bilaterally symmetrical due to larger hearing shifts occurring in better ears of subjects with preexisting hearing asymmetries. Recovery from temporary threshold shift in second ears tested was judged not to be a significant determinant for high prevalence of unilateral shifts. Many factors likely interact to confound interpretive value of OSHA shift laterality in occupationally noise-exposed populations. This holds important implications for hearing conservation program professionals considering hearing shift laterality as a factor in shift etiology.

Adult↗
PubMed1993

The efficacy of injectable and pour-on formulations of moxidectin against lice on cattle.

The efficacy of one administration of moxidectin against natural infestations of the 3 common species of cattle lice in Australia: Linognathus vituli, Damalinia bovis and Haematopinus eurysternus, was determined. A high degree of control of L vituli (the long-nosed sucking louse) was achieved with both the cattle injection (96.7% and 100%) at 0.2 mg/kg and the cattle pour-on formulation (94.6% and 100%) at 0.5 mg/kg on the 2 farms where this louse occurred. An injection of moxidectin at 0.2 mg/kg did not eliminate D bovis. In these trials efficacy ranged from nil to 85.2%. In contrast the pour-on formulation at 0.5 mg/kg provided consistently high efficacy (83.6 to 100%) against D bovis on 3 farms. Infestations of H eurysternus (the short-nosed sucking louse) were low and no significant difference was recorded between treatment groups in a single trial, however, lice persisted on 3 to 7 cattle in the untreated group at each inspection, whereas none were found on any animals in the 2 groups treated with moxidectin on inspection after treatment.

Administration, Topical↗
PubMed1993

No effect of mop-ending on ligament healing. Rabbit studies of severed collateral knee ligaments.

We have tested the hypothesis that increasing the surface area of cut ligament ends by the creation of "mop-ends" may alter the mechanical properties of healing medial collateral ligaments. In one group of New Zealand white rabbits, a 4-mm midsubstance segment was removed from the right ligament creating a gap (sharp cut-end healing group). In the other group, a similar gap was created but, in addition, cut ligament ends were split longitudinally across the width of the ligament creating "mop-ends", roughly tripling the total injury surface area. In all animals, the contralateral (left) leg was not operated on and served as an internal control. At least 8 animals from each injury model were killed at 3, 6, 14, and 40 weeks post-operatively. Both histological and mechanical tests showed that sharp-cut and mop-end injuries healed at similar rates with similar material.

Animals↗
PubMed1992

Australian reports into drug use and the possibility of heroin maintenance.

Official Australian reports into drug use reveal a high level of agreement over the nature of drug use and the problems associated with drug use. We examine the lines of argument which make up the shared approach of past reports into drugs, and assess to what degree the connections between these lines of argument are changing. This assessment reflects on the possibility of arguing that heroin should be made available for the treatment (including maintenance) of heroin-dependent users. This paper is derived from a report prepared for a feasibility study which examined whether or not heroin should be made available in the Australian Capital Territory in a controlled manner. After a close reading of a number of official reports, we conclude that it is possible to argue that heroin should become available.

Journal Article↗
PubMed1992

Posttranscriptional regulation by the human immunodeficiency virus type 1 Rev and human T-cell leukemia virus type I Rex proteins through a heterologous RNA binding site.

The human immunodeficiency virus type 1 Rev and human T-cell leukemia virus type I Rex proteins induce cytoplasmic expression of incompletely spliced viral mRNAs by binding to these mRNAs in the nucleus. Each protein binds a specific cis-acting element in its target RNAs. Both proteins also associated with nucleoli, but the significance of this association is uncertain because mutations that inactivate nucleolar localization signals in Rev or Rex also prevent RNA binding. Here we demonstrate that Rev and Rex can function when tethered to a heterologous RNA binding site by a bacteriophage protein. Under these conditions, cytoplasmic accumulation of unspliced RNA occurs without the viral response elements, mutations in the RNA binding domain of Rev do not inhibit function, and nucleolar localization can be shown to be unnecessary for the biological response.

Amino Acid Sequence↗
PubMed1992

Collagen fibril diameters in the healing adult rabbit medial collateral ligament.

This study was carried out to test the hypothesis that improvements in ligament scar mechanical behavior during healing may be related, in part, to increases in collagen fibril diameters. Forty-eight adult female New Zealand White rabbits had standardized midsubstance gap injuries created in their right medial collateral ligaments (MCLs) and were allowed normal cage activity until sacrifice in groups of 12 at 3, 6, 14 or 40 weeks post-injury. Eight animals in each group had both MCLs tested biomechanically while 4 animals had transmission EM investigation of midsubstance collagen fibril diameters by a standardized protocol. Results of mechanical tests showed a three- to fourfold increase in scar strength and stiffness over the intervals of healing studied while there was no change in collagen mean fibril minimum diameters. These results demonstrate no correlation between material or structural properties of scar and collagen fibril diameters in this model of healing and suggest that other mechanisms for scar mechanical improvement under these conditions must be investigated.

Animals↗
PubMed1991

Drug use patterns in Northern Territory Aboriginal communities 1986-1987.

During April to November 1986 and May to October 1987, a systematic survey of patterns of use of alcohol, kava, tobacco and analgesics by Northern Territory Aboriginal people aged 15 years and older was conducted. The objectives of the study were to ascertain the prevalence of drug use, the frequency of drug use and the quantity of drugs used. In addition, information about Aboriginal people's perceptions of the drugs, their beliefs about drug use and the value of drugs in their culture was collected. This paper describes only the quantitative aspects of drug use of this population. A stratified sampling procedure was used to sample 10 per cent of the target population. Using two survey instruments, an individual questionnaire and a group questionnaire, data were gathered from 1764 Aboriginal people living in the Northern Territory. As a whole, the Northern Territory Aboriginal people have a drug consumption pattern quite distinct from urban Australians.

Journal Article↗