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Biomedical subjects

M Walker

Publications and source records attributed to M Walker.

At least 307 records · Page 17Linked to original sources
PubMed1995

"False" migration of rigid fixation appliances in pediatric craniofacial surgery.

Osseous fixation techniques have been widely used to provide rigid stabilization in the craniofacial skeleton. Reported sequelae of its usage has been limited to palpation of the screw-plate system and radiological imaging artifacts. Over the past 3 years we have identified miniplates, microplates, and wire sutures on the inner cranial table of the growing child. The observation of "false" migration of these appliances has provided the impetus to review these patients in more detail. Twenty patients underwent secondary cranial remodeling within a two-year period; 7 of these patients were seen to have "false" migration. There were no untoward sequelae in removal of these appliances, and no adverse neurological symptoms were seen.

Bone Plates↗
PubMed1995

NICU care.

Explore the source record for details and available documents.

Humans↗
PubMed1995

Factors determining case fatality in myocardial infarction "who dies in a heart attack"?

OBJECTIVE: To examine the determinants of case fatality in the first major ischaemic heart disease event (heart attack) after screening. METHODS: Prospective study of 7735 middle aged men drawn from general practices in 24 British towns. RESULTS: During 11.5 years follow up there were 743 major ischaemic heart disease events of which 302 (40.6%) were fatal within 28 days of onset. Previous definite myocardial infarction or stroke and age at time of event were most strongly associated with case fatality. In men with no previous myocardial infarction or stroke, after adjustment for a range of risk factors, antihypertensive treatment (odds ratio (OR) = 1.97, P < 0.05), arrhythmia (OR = 1.93, P = 0.06), increased heart rate (OR = 2.03, P = 0.06), and diabetes (OR = 2.61, P = 0.07) were associated with increased case fatality. High levels of physical activity (OR = 0.53, P < 0.05) and moderate drinking (16-42 units/week) (OR = 0.61, P < 0.05) were associated with lower case fatality, although moderate drinking was not associated with a lower incidence of major ischaemic heart disease events. Current smoking, serum total cholesterol, and systolic blood pressure were not significantly associated with case fatality. In men with previous myocardial infarction or stroke, arrhythmia and to a lesser degree antihypertensive treatment, moderate or heavy drinking, and diabetes were associated with higher case fatality. CONCLUSION: These findings suggest that physical activity may be an important modifiable factor influencing the incidence of ischaemic heart disease and the chance of survival in men without a previous heart attack or stroke. Arrhythmia, increased heart rate, diabetes, and treatment for hypertension are also areas of concern.

Adult↗
PubMed1995

Pediatric cervical spine instrumentation using screw fixation.

From July 1986 to August 1993 we performed 24 pediatric cervical spine screw fixation procedures on 23 patients 16 years of age or less. The types of cervical instrumentation procedures performed were as follows: anterior cervical plates 12, posterior C1-2 screw fixations 8, posterior lateral mass plates 2, odontoid screw fixations 2. The mean age of all patients was 14.2 years (range 6-16). Indications for operation included traumatic instability in 20 cases, congenital instability in 1 case, 2 cases of postoperative swan neck deformity, and one reoperation for early graft and hardware failure. Six of the 23 patients had persistent instability following previous failed fusions (3 with 1 prior surgery, 2 with 2 prior surgeries, and 1 with 3 prior surgeries). Eight patients had improvement of their neurological status following operation and 15 remained at their preoperative level of neurological function. No patient was worse neurologically after their procedure. There were no long-term instrumentation, graft or fusion failures. Two complications occurred. One was the aforementioned graft and hardware failure requiring reoperation, the other was a superficial wound infection treated successfully with antibiotics. We feel that cervical spine fixation techniques have increased our ability to stabilize the pediatric cervical spine and have proven to be safe and effective.

Adolescent↗
PubMed1995

Features of syndrome X in first-degree relatives of NIDDM patients.

OBJECTIVE: To determine whether the features of syndrome X are more common in first-degree relatives of non-insulin-dependent diabetes mellitus (NIDDM) patients than in control subjects with no family history of diabetes. RESEARCH DESIGN AND METHODS: A total of 154 first-degree relatives from 60 families with two or more NIDDM patients and 154 age- and sex-matched control subjects were studied. All subjects underwent a 75-g oral glucose tolerance test and baseline lipid blood and anthropometric measures. The features of syndrome X that were studied were obesity, hypertension, dyslipidemia (high triglyceride levels and low high-density lipoprotein [HDL] cholesterol concentrations), impaired glucose tolerance (World Health Organization criteria), and insulin resistance (as assessed by the homeostasis model assessment). RESULTS: Relatives were heavier than control subjects (body mass index 27.5 +/- 5.2 vs. 25.2 +/- 4.6 kg/m2, respectively [mean +/- SD], P < 0.0002), had lower HDL cholesterol concentrations (1.2 +/- 0.3 vs. 1.4 +/- 0.4 mmol/l, P < 0.001), were more insulin-resistant (2.3 [0.7-7.6] vs. 1.6 [0.5-5.1], geometric mean [95% confidence intervals], P < 0.0001), and had more individuals classified as having impaired glucose tolerance (28 of 154 [18%] vs. 7 of 154 [7%], chi 2, P < 0.001). The differences in insulin resistance and HDL cholesterol concentrations between the groups were independent of obesity. CONCLUSIONS: Features of syndrome X occur more frequently in relatives of NIDDM patients than in control subjects with no family history of diabetes.

Adult↗
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↗
PubMed1995

Characterization of acute bone marrow graft rejection in T cell-depleted, partially mismatched related donor bone marrow transplantation.

The purpose of this study was to characterize the phenotype and clonality of the T cell population in patients who experience acute rejection (AR) following bone marrow transplantation (BMT) from a partially mismatched related donor (PMRD). Phenotypic analysis was performed using flow cytometry, assignment of donor/host lineage by cytogenetics or HLA-specific flow cytometry, and analysis of the T cell receptor (TCR) by reverse-transcriptase polymerase chain reaction (RT-PCR). We have previously reported the initial appearance in the blood of AR patients of host CD8+brightCD3low T cells that progressively express increasing amounts of CD3+ cells. We now report that this cell population can differentiate into either a cytotoxic T cell phenotype (CD3+CD8+HLA-DR+CD57-) usually associated with AR of grafts from matched unrelated donors or a suppressor T cell phenotype (CD3+CD8+CD57+HLA-DR-) usually associated with AR of grafts from matched sibling donors. Analysis of the TCR V beta subsets from two patients revealed sorted host CD3+CD8+ cells (purity 90-95%) from the first patient to express V beta 18 almost exclusively. In a second patient with late rejection (55 days post-BMT), the CD3+CD8+ cells were predominantly restricted to V beta 1, 5.1, 7, 9, and 18. Although CD3+CD8+ T cells are known to be associated with AR, cytotoxic and suppressor lineages in AR from the same type of BMT and clonal distribution of T cells in AR have not been reported. Preliminary results suggest that V beta expression in AR of PMRD grafts is restricted and host T cell phenotype may vary. Further studies will investigate whether specific mismatches correlate with specific V beta usage and/or host T cell phenotype.

Base Sequence↗
PubMed1995

Resting electrocardiogram and risk of coronary heart disease in middle-aged British men.

OBJECTIVE: To examine the relation between resting electrocardiographic (ECG) abnormalities and risk of coronary heart disease (CHD). DESIGN AND SETTING: This was a prospective study of 7735 middle-aged men aged 40-59 years at entry (British Regional Heart Study). At baseline assessment each man completed a modified World Health Organization (WHO) (Rose) chest-pain questionnaire, gave details of his medical history and had a three-lead orthogonal electrocardiogram recorded. "Symptomatic CHD' refers to a history of anginal chest pain and/or a prolonged episode of central chest pain on WHO questionnaire and/or recall of a doctor diagnosis of CHD (angina or myocardial infarction). MAIN OUTCOME MEASURES: These were the first major CHD events, i.e. fatal CHD and non-fatal myocardial infarction, occurring during 9.5 years of follow-up. RESULTS: Of 611 first major CHD events during follow-up, 243 (40%) were fatal. After adjustment for age, other ECG abnormalities and symptomatic CHD, the ECG abnormalities most strongly associated with risk of a major CHD event were definite myocardial infarction (relative risk 2.5; 95% confidence interval 1.8-7.5) and definite myocardial ischaemia (1.9; 1.1-2.9). Other ECG abnormalities independently associated with a statistically significant increase in risk were left ventricular hypertrophy (2.2; 1.5-3.3), left axis deviation (1.3; 1.1-1.6) and ectopic beats, particularly if these were ventricular (1.6; 1.1-2.4). Three ECG abnormalities associated with a marked increase in CHD case-fatality rate were pre-existing myocardial infarction (67%), major conduction defect (71%) and arrhythmia (67%); the rate in men with none of these abnormalities was 32%. The relative risks associated with each ECG abnormality were similar in men with and without symptomatic CHD. The increase in risk in the presence of symptomatic CHD (2.4-fold) and ECG evidence of definite myocardial infarction (2.5-fold) was similar; the presence of both factors increased risk more than six-fold. The most serious ECG abnormalities-definite myocardial infarction and ischaemia-were useful predictors of future major CHD events only in men with symptomatic CHD. CONCLUSION: The prognostic importance of major ECG abnormalities is strongly influenced by the presence of symptomatic CHD. In men with symptomatic CHD the resting electrocardiogram may help to define a group at high risk who may benefit from intervention. However, it has little or no value as a screening tool in middle-aged men without symptomatic CHD.

Adult↗
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↗