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Biomedical subjects

M Williams

Publications and source records attributed to M Williams.

At least 343 records · Page 19Linked to original sources
PubMed1996

Doing the conjugative two-step: evidence of recipient autonomy in retrotransfer.

Bidirectional exchange of genetic information, called retrotransfer, during bouts of bacterial conjugation has drawn the interest of those concerned with the risk of releasing genetically engineered microbes, the fluidity of genes among species, and the mechanism of DNA transport between cells. The phenomenon has generated two models in explanation, both of which yield highly testable predictions. The first model, called the one-step, predicts that the flow of genes from recipient bacteria to donor bacteria is mechanistically distinct from, but dependent on, conjugation between donors and recipients. The second model, called the two-step, predicts that the same genetic requirements and mechanistic constraints apply to the process of gene flow from recipients to donors as for gene flow from donors to recipients. The requirement for expression of at least 10 plasmid-encoded genes in recipients, sensitivity of the reverse flow (recipient to donor) to restriction of DNA transferring from the donor, and the requirement of an additional 30-90 min for DNA to flow from recipients back to donors are predictions of the two-step model and directly refute the one-step model. Retrotransfer of genes to donors during conjugation remains genetically and physically indistinguishable from two successive rounds of conjugation between neighbors.

Conjugation, Genetic↗
PubMed1996

Sickness absence following a campaign of vaccination against influenza in the workplace.

This study was designed as a retrospective cohort study of those employees vaccinated against influenza vs. unvaccinated employees in a service company. The objective was to investigate whether vaccinating employees against influenza in an occupational setting was of any benefit. There were 2,557 persons entered in the study who were in continuous employment between 1 October 1990 and 31 March 1992 of which 23.5% (601) were vaccinated. The study was carried out at First Data Resources Limited in Basildon, Essex UK. The main outcome measure was self-reported influenza sickness lasting four or more days and reduction in sickness absence due to vaccination against influenza. The results were surprising. In the vaccinated members of staff, influenza illness was halved, Relative Risk = 0.46, 95% confidence limits (0.27 < RR < 0.76). The conclusions were that the study showed a significant decrease in sickness absence due to influenza illness, as a result of an active vaccination campaign carried out amongst otherwise healthy individuals in the occupational health environment. This is the first study of this nature in the UK to show statistically significant evidence of benefit from vaccinating healthy employees. It lends support to immunization against influenza in the workplace.

Absenteeism↗
PubMed1996

Nursing orientation: a continuous quality improvement story.

THIS ARTICLE ADDRESSES an orientation process utilizing a collaborative, multidisciplinary approach and principles of continuous quality improvement (CQI). This process successfully transitioned 63 graduate nurses into three different practice specialties, decreased the vacancy rate, and eliminated the need for agency nurses at Georgia Baptist Medical Center in Atlanta, Georgia. CNSs, acting as educators, clinical experts, and consultants, played a key role in developing, implementing, and evaluating this comprehensive program.

Clinical Competence↗
PubMed1996

Effects of exercise intensity on 24-h energy expenditure and substrate oxidation.

The purpose of this study was to determine: 1) the reliability of 24-h respiratory calorimetry measurements, and 2) the effects of low- versus high-intensity exercise on energy expenditure (EE) and substrate oxidation over a 24-h period. Eight women (age 28 +/- 4.3 yr) were measured for body composition, maximal oxygen consumption while cycling, and EE in three, 24-h calorimeter tests, with identical work output but differing intensity during a 60-min exercise session. Low-intensity (LI) exercise involved continuous cycling at 50% VO2max; whereas high-intensity (HI) exercise involved interval cycling (2 min exercise/recovery) at 100% VO2max. Subjects were randomly assigned to the first two tests at LI or HI, with the third test at the alternate intensity. No differences in EE or respiratory quotient (RQ) during rest, sleep, exercise, or over the 24 h were found between the first two tests (C.V. = 6.0%), demonstrating the reliability of the measurements. The HI protocol elicited significantly higher EE than LI during rest, exercise, and over 24 h, whereas sleeping EE approached significance. No significant differences in RQ during rest, sleep, or over 24 h were found, but 24-h lipid and carbohydrate oxidation were similar in the two protocols. The HI exercise RQ was significantly higher than LI. These findings demonstrated higher 24-h EE in the HI than LI protocol, but similar 24-h substrate oxidation rates.

Adult↗
PubMed1996

Angiographic and duplex grading of internal carotid stenosis: can we overcome the confusion?

The stroke risk reduction benefit of surgical intervention in carotid occlusive disease has been validated in multicenter trials for various angiographically defined lesion severity categories. The two divergent angiographic grading methods used for internal carotid artery stenosis in these trials have caused confusion in the clinical application of their recommendations. Moreover, while today's highly accurate carotid duplex scanning can obviate the need for preoperative angiography in many cases, the duplex criteria must be tailored to achieve sufficiently reliable results on which therapeutic decisions can be made. This review offers a clarification of the discrepancies between the angiographic grading techniques and how their measurements of percent stenosis correlate to the duplex criteria needed to support the treatment decision-making process for carotid obliterative disease.

Angiography↗
PubMed1996

The advantages of an unsteady panel method in modelling the aerodynamic forces on rigid flapping wings

This paper responds to research into the aerodynamics of flapping wings and to the problem of the lack of an adequate method which accommodates large-scale trailing vortices. A comparative review is provided of prevailing aerodynamic methods, highlighting their respective limitations as well as strengths. The main advantages of an unsteady aerodynamic panel method are then introduced and illustrated by modelling the flapping wings of a tethered sphingid moth and comparing the results with those generated using a quasi-steady method. The improved correlations of the aerodynamic forces and the resultant graphics clearly demonstrate the advantages of the unsteady panel method (namely, its ability to detail the trailing wake and to include dynamic effects in a distributed manner).

Journal Article↗
PubMed1996

ABT-431: the diacetyl prodrug of A-86929, a potent and selective dopamine D1 receptor agonist: in vitro characterization and effects in animal models of Parkinson's disease.

(-)-Trans 9,10-hydroxy-2-propyl-4,5,5a,6,7,11b-hexahydro-3-thia-5- azacyclopent-1-ena[c]phenanthrene hydrochloride (A-86929) is a potent and selective full agonist at the dopamine (DA) D1-like receptor. Judging by its binding affinities to the D1 and D2 classes of receptors, the compound is approximately 20-fold D1 receptor-selective, whereas relative potencies based on functional in vitro assays indicate that A-86929 is greater than 400-fold D1-selective. A-86929 has moderate to weak (Ki > 1 microM) affinity at other monoaminergic and peptidergic receptors, at ion channels and at monoamine uptake sites. The catechol of A-86929 was bis-acetylated to produce the prodrug, (-)-trans 9,10-acetoxy-2-propyl-4,5,5a,6,7,11-b-hexahydro-3-thia- 5-azacyclopent-1-ena[c]phenanthrene hydrochloride (ABT-431), which is more chemically stable yet is rapidly converted to the parent compound with a half-life of less than 1 min in plasma. Both A-86929 and ABT-431 produced contralateral rotation in rats bearing unilateral 6-hydroxydopamine lesions, with ED50 values of 0.24 mumol/kg s.c. and 0.54 mumol/kg s.c., respectively. A-86929 and ABT-431 improved behavioral disability scores and increased locomotor activity in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned marmoset model of Parkinson's disease in a dose-dependent manner (the minimum effective dose was 0.10 mumol/kg s.c.). When administered three times daily for 30 consecutive days to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned marmosets, A-86929 significantly improved disability scores throughout the duration of the study. Current Parkinson's disease therapy includes L-dopa, which stimulates both classes of DA receptors by virtue of its conversion to DA in vivo, and direct-acting D2-selective agonists. Stimulation of the D2 receptor, which is associated with all current DA agonist-based therapies, may contribute to their dose-limiting side effects. An agent such as A-86929 (or its prodrug ABT-431), which selectively stimulates the D1 receptor, may represent a novel mechanism for Parkinson's disease therapy with the potential for an improved side-effect profile and, consequently, improved patient compliance.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

Infection control and universal precautions.

Surgical interventions are now carried out in many settings other than purposely designed operating theatre suites. NATN is pleased to welcome nurses working in areas other than operating theatres to associate membership of the Association. In response to this diversity of surgical settings, an examination of the basic principles of infection control and the application of universal precautions may be valuable.

Humans↗
PubMed1996

Quality in a contracting environment.

Since the introduction of an internal market in health care, the forces which influence other types of service providing businesses have become important in the National Health Service. Marketing of services, identifying and targeting customers and cost are some of these influences. If customers are to be competed for by service providers, then the quality of the service provided will also be a consideration.

Contract Services↗
PubMed1996

Anthropometric equations for estimating abdominal adipose tissue distribution in women.

OBJECTIVES: (1) to develop multiple regression equations for predicting computed tomography (CT) derived intra-abdominal (IAF), subcutaneous (SCF) and total (TOTF = IAF + SCF) abdominal adipose tissue areas from anthropometric measures and (2) to validate the equations. DESIGN: Cross-sectional study. SUBJECTS: 204 healthy Caucasian females subjects with a large range of age (17-76 years) and percentage body fat (8.8%-48.1%). Fifty-one subjects served as an independent sub-sample for the validation of the equations. MEASUREMENTS: Various fatness and fat distribution parameters (hydrodensitometry, single CT scan, skinfold and circumference measures). RESULTS: Multiple regression equations were developed to estimate IAF, SCF and TOTF. R2 for IAF, SCF and TOTF was 0.75, 0.81 and 0.85, respectively. The equations were validated on an independent sub-sample of 51 subjects. All three equations met validation criteria with R2 validations of 0.79, 0.71 and 0.84 for IAF, SCF and TOTF, respectively. CONCLUSION: These equations might be used as an inexpensive estimation of IAF, SCF and TOTF in adult Caucasian females varying greatly in age and percentage body fat.

Abdomen↗
PubMed1996

Intraarterial thrombolysis in vertebrobasilar occlusion.

PURPOSE: To report our experience using intraarterial thrombolysis in the treatment of vertebrobasilar occlusion. METHODS: Twelve patients with 13 angiographically proved thromboses of the vertebrobasilar system underwent local intraarterial thrombolysis with urokinase. Angiographic and clinical outcomes were analyzed with respect to clinical examination at presentation, arterial occlusion patterns, and time to recanalization. RESULTS: The overall mortality was 75%. Recanalization could not be achieved in 3 of 13 treatments; all patients in whom recanalization failed died. The mortality rate was 60% in those patients in whom recanalization was successful. Coma or quadriparesis at the time of therapy uniformly predicted death. There were two cases each of bilateral proximal vertebral occlusions and midbasilar occlusions and nine cases of bilateral distal vertebral occlusions. There were three cases of fatal rethrombosis after initial successful thrombolysis. The mortality rate in the recanalized group before rethrombosis was 30%. There were two fatal hemorrhages of the central nervous system. CONCLUSION: Recanalization of the vertebrobasilar system is necessary but not sufficient for effective treatment of vertebrobasilar occlusive disease. The site of occlusion may help predict angiographic and clinical outcome. Time to initiation of thrombolysis is not an invariable correlate of survival, although clinical condition at presentation may be. Rethrombosis and hemorrhage are significant problems affecting mortality after successful thrombolysis.

Aged↗
PubMed1995

Complex and rapid-cycling in bipolar children and adolescents: a preliminary study.

26 subjects aged 7-18 years were studied. Diagnoses of bipolar disorders were established using the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present Episode Version-1986 modified for DSM-III-R criteria and for rating the number and duration of manic and hypomanic episodes. Complex cycling patterns were observed. These included numerous brief episodes suggesting continuous rapid-cycling in 80.8% of cases. Mean age of onset was early (8.5 +/- 4.4 years). Psychotic phenomena, suicidality, hyperactivity and 'mixed mania' were highly prevalent. Data in this report provide support for complex and rapid-cycling patterns in childhood onset bipolar disorder.

Adolescent↗