Search PubMed⌕ Search

Biomedical subjects

M Walker

Publications and source records attributed to M Walker.

At least 37 records · Page 2Linked to original sources
PubMed1995

Scoring system to identify men at high risk of stroke: a strategy for general practice.

BACKGROUND: The major risk factors for stroke are well described and there is good evidence that the risks associated with hypertension and cigarette smoking are reversible by appropriate interventions. However, if disease prevention measures are to be efficient, it is important that a system which can identify individuals at high risk of stroke be available for use in general practice. AIM: A study was therefore undertaken to design an effective and practical system for detecting men aged 40 to 59 years at high risk of stroke in primary care. METHOD: Stroke incidence and risk factor data were examined in a cohort of 7735 men aged 40 to 59 years who had taken part in the British regional heart study. Analysis was performed using data from initial entry into the study and then from five and 11.5 years of follow up. Subjects were randomly selected from the age-sex register of one general practice in each of 24 different towns throughout the United Kingdom, representing the full range of cardiovascular mortality rates. RESULTS: A simple scoring system derived from logistic regression using age, systolic blood pressure, current cigarette consumption, and evidence of anginal chest pain was able to detect more than 80% of all strokes occurring within five years in the top fifth of the score distribution. The inclusion of other risk factors for stroke did not increase the score's predictive ability. The combination of smoking and hypertension, while much less sensitive than the scoring system, was a better indicator of risk than any single risk factor, all of whose predictive values were poor. CONCLUSION: Based on readily measured variables, this scoring system could be used in general practice to identify men at high risk of stroke who would benefit from further intervention. Effective identification of high risk individuals requires assessment of the combined effects of multiple risk factors.

Adult↗
PubMed1995

Millisecond time resolution electron cryo-microscopy of the M-ATP transient kinetic state of the acto-myosin ATPase.

The structure of the AM-ATP transient kinetic state of the acto-myosin ATPase cycle has been examined by electron microscopy using frozen-hydrated specimens prepared in low ionic strength. By spraying grids layered with the acto-S1 complex with ATP immediately before freezing, it was possible to examine the structure of the ternary complex with a time resolution of 10 ms. Disordered binding of the S1 was observed, suggesting more than one attachment geometry. This could be due to the presence of more than one biochemical intermediate, or to a single intermediate binding in more than one conformation.

Adenosine Triphosphate↗
PubMed1994

Schizophrenia and mental retardation associated in a pedigree with retinitis pigmentosa and sensorineural deafness.

A family is presented with multiple cases of mild mental retardation, schizophrenia and other functional psychoses, progressive hearing loss, and retinitis pigmentosa (RP). It closely resembles a previously reported Finnish family. We suggest that the phenotypes are not associated in this family by chance, but define a novel syndrome which may be caused by a mutant allele at a single genetic locus.

Adolescent↗
PubMed1994

A nuclear mutation in maize blocks the processing and translation of several chloroplast mRNAs and provides evidence for the differential translation of alternative mRNA forms.

A mutant designated crp1 (chloroplast RNA processing 1) was identified in a screen for transposon-induced maize mutants with defects in chloroplast gene expression. crp1 is a recessive, nuclear mutation that causes the loss of the cytochrome f/b6 complex and a reduction in photosystem I. The molecular basis for these protein losses is unique relative to previously described mutants with defects in organelle gene expression; it involves defects in the metabolism of two organellar mRNAs and in the translation of two organellar proteins. Mutants lack the monocistronic forms of the petB and petD mRNAs (encoding cytochrome f/b6 subunits), but contain normal levels of their polycistronic precursors. Pulse-labeling experiments revealed normal synthesis of the petB gene product, but a large decrease in synthesis of the petD gene product. These results suggest that petD sequences are more efficiently translated in a monocistronic than in a polycistronic context, thereby providing evidence that the elaborate RNA processing typical of chloroplast transcripts can play a role in controlling gene expression. Structural predictions suggest that the petD start codon lies in a stable hairpin in the polycistronic RNA, but remains unpaired in the monocistronic transcript. Thus, processing to a monocistronic form may increase translational efficiency by releasing the translation initiation region from inhibitory interactions with upstream RNA sequences. Synthesis of a third cytochrome f/b6 subunit, encoded by the petA gene, was undetectable in crp1, although its mRNA appeared unaltered. Two mechanisms are consistent with the simultaneous loss of both petA and petD protein synthesis: the translation of the petA and petD mRNAs might be coupled via a mechanism independent of crp1, or the crp1 gene may function to coordinate the expression of the two genes, which encode subunits of the same complex.

Alternative Splicing↗
PubMed1994

Development and validation of the Stirling Eating Disorder Scales.

The development and reliability/validity check of an 80-item, 8-scale measure for use with eating disorder patients is presented. The Stirling Eating Disorder Scales (SEDS) assess anorexic dietary behavior, anorexic dietary cognitions, bulimic dietary behavior, bulimic dietary cognitions, high perceived external control, low assertiveness, low self-esteem, and self-directed hostility. The SEDS were administered to 82 eating disorder patients and 85 controls. Results indicate that the SEDS are acceptable in terms of internal consistency, reliability, group validity, and concurrent validity.

Adult↗
PubMed1994

Electron cryomicroscopy of acto-myosin-S1 during steady-state ATP hydrolysis.

The structure of the complex of actin and myosin subfragment-1 (S1) during steady-state ATP hydrolysis has been examined by electron microscopy. This complex is normally dissociated by ATP in vitro but was stabilized here by low ionic strength. Optimal conditions for attachment were established by light-scattering experiments that showed that approximately 70% of S1 could be bound in the presence of ATP. Micrographs of the unstained complex in vitreous water suggest that S1 attaches to actin in a variety of configurations in ATP; this contrasts with the single attached configuration seen in the presence of ADP. The data are therefore compatible with the idea that a change in attached configuration of the myosin cross-bridge is the origin of muscle force. In control experiments where ATP was allowed to hydrolyze completely the binding of the S1 seemed cooperative.

Adenosine Diphosphate↗
PubMed1994

Open-mouth posture and maxillary arch width in young children: a three-year evaluation.

A large biracial sample of children were assessed for open mouth posture and maxillary arch width once a year for 3 years. Analyses revealed that although the youngsters exhibited open-mouth posture at high levels, over time, there was a significant decrease in this behavior. Racial and gender differences, as well as a race-by-time interaction, were also evidenced. The children displayed a significant increase in maxillary arch width across time, with gender and racial differences seen in this growth pattern. Finally, when the youngsters were classified as exhibiting primarily open-mouth or closed-mouth posture, it was observed that children with open-mouth posture displayed a significantly slower pattern of maxillary growth compared with children who display anterior lip seal posture. The implications of the findings were discussed.

Analysis of Variance↗
PubMed1994

A longitudinal evaluation of open mouth posture and maxillary arch width in children.

Open mouth posture and maxillary arch width were assessed annually for 4 years in a group of children. While younger children exhibited high levels of open mouth posture, this behavior decreased significantly over time. Racial and sex differences, as well as a race-by-time interaction were also evident. The children displayed a significant increase in maxillary arch width across time with sex and racial differences in this growth pattern. Subjects were classified as exhibiting primarily open mouth or closed mouth posture. Although both groups showed increased maxillary arch widths over time, the closed mouth subjects showed significantly greater maxillary arch growth.

Analysis of Variance↗
PubMed1994

Concepts in nurse education.

This paper reports a case study of student and senior nurses at the Royal Free Hospital, London, England. Qualitative methods were used to investigate the perceptions of nursing upon which students and senior nurses based their activities on the wards. Differences were identified between the ways in which students and senior nurses 'saw' their day-to-day tasks. Analysis showed that these differences were based upon differing levels of conceptualization. Student nurses were found to operate with low levels of conceptualization and were thus unable to categorize or group the patients, procedures or problems confronting them. Senior nurses, on the other hand, operated with a high level of conceptualization and were able to perceive similarities in objects, events and processes and to differentiate these into categories, classes or patterns. This allowed them to prioritize lines of action and to respond to situations in a rational and effective way. The problem for nurse education, then, is how best to enable students to develop a professional level of conceptualization. Strategies are identified by which senior nurses might enable student nurses to develop concepts in relation to their nursing activities on the wards.

Attitude of Health Personnel↗
PubMed1994

Relapse of medically treated insulinoma following the development of thyrotoxicosis: an assessment of potential mechanisms.

Increased thyroid hormone concentrations have been reported to have disparate effects on insulin sensitivity in man. We describe a 72-year-old lady who initially presented with episodic hypoglycemia secondary to an insulinoma that was controlled by diazoxide. She re-presented 12 months later with a recurrence of the hypoglycemia following the development of thyrotoxicosis. The diazoxide treatment was maintained and propranolol was introduced, which prevented further episodes of hypoglycemia. This appeared to be due to a direct effect of propranolol on endogenous insulin secretion, while whole body insulin sensitivity remained unchanged as assessed using the hyperinsulinemic-euglycemic clamp technique. She was later rendered biochemically euthyroid with a combination of blocking carbimazole therapy and thyroxine replacement, and this was associated with a marked decrease in insulin sensitivity. Thus, the principal effect of thyroid hormone excess in this patient was an increase in insulin sensitivity that led to the clinical relapse of the insulinoma.

Aged↗
PubMed1994

Alcohol and coronary heart disease: a perspective from the British Regional Heart Study.

BACKGROUND: A number of studies have shown that light or moderate alcohol intake is associated with a reduced incidence of coronary heart disease (CHD) compared with non-drinkers. There is controversy as to whether this is due to a specific protective effect of alcohol or whether the increased risk of CHD in non-drinkers is due to selective migration of high-risk subjects from drinking into non-drinking categories. METHODS: A prospective study of men aged 40-59 years drawn at random from one general practice in each of 24 British towns, and followed for cardiovascular morbidity and all-cause mortality over a 9.5-year period. RESULTS: There was a shallow U-shaped relationship between alcohol intake and all major CHD events and a strong inverse association with fatal CHD events. In men with no evidence of CHD at screening, despite a 28% (non-significant) reduction in the relative risk of fatal CHD events in men drinking 2-6 drinks/day, the difference in absolute rates of CHD between the drinking categories was small. Men with symptomatic CHD showed a strong inverse association between alcohol and all major CHD events and fatal CHD events. In men without a doctor diagnosis of cardiovascular disorder, those drinking 2-6 drinks/day showed a 34% (non-significant) reduction in relative risk of CHD death compared to occasional drinkers but little reduction in total cardiovascular mortality and no reduction in all-cause mortality. CONCLUSION: These findings provide weak support for the protective effect of alcohol on CHD and no encouragement for regular moderate drinking on the grounds of benefit to health.

Adult↗
PubMed1994

Effect of hyperinsulinaemia on the function of the pituitary-adrenal axis in healthy man.

OBJECTIVE: Circulating insulin levels in themselves have been reported to influence the counter-regulatory hormone response to hypoglycaemia in man. The effect of insulin on a specific aspect of this response was examined during euglycaemia by stimulating the pituitary-adrenal axis with human corticotrophin-releasing hormone (CRH). SUBJECTS: Eight healthy males. DESIGN: Following an overnight fast, insulin was infused at 15 (low) and 60 (high) mU/kg/h from 0900 h for 180 minutes on separate occasions in random order. On each occasion, blood glucose was clamped at euglycaemia, and 1 microgram/kg (i.v. bolus) human CRH was administered at 120 minutes. MEASUREMENTS: Circulating hormone concentrations were determined by radioimmunoassay. Peak cortisol and ACTH responses were compared for the two study conditions. RESULTS: Mean serum insulin levels were threefold higher during the high compared with the low insulin infusion (mean difference 320 pmol/l, 95% confidence interval (CI) 150-490, P < 0.001). Blood glucose levels during the clamps were comparable (mean difference 0.15 mmol/l, 95% CI 0-0.63). Plasma cortisol levels increased following CRH, although the peak concentration was significantly lower during the high insulin infusion (mean difference 36 nmol/l, CI 0-110, P < 0.02). However, peak ACTH levels were comparable for the two insulin levels (mean difference 8 ng/l (1.8 pmol/l), CI 0-50). CONCLUSIONS: The peak cortisol response to CRH was diminished at the higher circulating insulin levels. This was not dependent upon concurrent hypoglycaemia and did not appear to be mediated at the level of the pituitary gland.

Adrenocorticotropic Hormone↗
PubMed1994

Nipple pain.

Explore the source record for details and available documents.

Breast Feeding↗