PubMed Health⌕ Search

Biomedical subjects

J Newell

Publications and source records attributed to J Newell.

At least 19 recordsLinked to original sources
PubMed2006

Using functional data analysis to summarise and interpret lactate curves.

John Tukey used the term exploratory data analysis (EDA) to describe a philosophy for analyzing data where graphical and numerical summaries are used to uncover interesting structures. The applied statistician today has a much more sophisticated set of methods to use when applying the EDA philosophy. One such collection of methods is functional data analysis (FDA), which was used to explore the structure of lactate curves. A principal components analysis and plots of the second derivatives provide new intuitive endurance markers which correlates highly with other numerical summaries of lactate curves that have been suggested in the literature.

Humans↗
PubMed2006

Incidence of injury in elite Gaelic footballers.

The purpose of this study was to undertake a comprehensive prospective epidemiological study of injuries sustained by elite Gaelic Football players over one season. The pattern of injury is strikingly similar across all teams with 47% of all injuries occurring in the final quarter of games and training. Injuries to the lower limb, particularly the hamstrings muscles accounted for the majority of injuries. 65% of players were unable to participate fully in Gaelic Football activity for between one and three weeks as a result of injury. The high incidence of injury especially hamstrings injuries in the latter stages of training and games warrants further investigation.

Adolescent↗
PubMed2005

Survival ratio plots with permutation envelopes in survival data problems.

A new method is proposed, based on a simple ratio plot, which is useful for identifying time intervals or regions in which survival prospects differ between two distinct populations or treatments. In order to investigate whether any observed difference or trend is due to sampling variation or is due to a possible real effect, resampling techniques are used to generate permutation envelopes as reference bands. The method is applicable to the comparison of survival in two populations for both independent and paired survival problems and also to the assessment of the symmetry of a bivariate survival function.

Computer Simulation↗
PubMed2005

Lactate threshold responses to a season of professional British youth soccer.

OBJECTIVE: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season. METHODS: Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-T(lac)) and at a blood lactate concentration of 4 mmol l(-1) (v-4mM) were determined. RESULTS: Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h(-1) for v-T(lac), and from 13.62 (0.25) to 14.67 (0.24) km h(-1) for v-4mM (p<0.001). However, v-T(lac )and v-4mM when expressed relative to maximum heart frequency (Hf(max)) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other. CONCLUSION: Running velocity at v-T(lac )and v-4mM increased significantly over the pre-season period, but v-T(lac )and v-4mM were unchanged when expressed relative to Hf(max). This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo(2max). Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo(2max) and running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions.

Adolescent↗
PubMed2004

The effect of health status on patients' satisfaction with out-of-hours care provided by a family doctor co-operative.

BACKGROUND: Systems for providing primary care outside normal hours have changed significantly in Europe over the last 20 years. The impetus for this change has come almost entirely from the medical profession, and it is important to consider the patients' perspective. Although patient's satisfaction with out-of-hours care has been studied extensively, the effect of patient's health status on satisfaction level has not been examined previously. OBJECTIVES: The primary objective of this study was to investigate whether health status has an influence on patient satisfaction with out-of-hours care provided by a family doctor co-operative. The secondary objective of this study was to investigate the impact of age, gender, socio-economic status and call outcome on patients' satisfaction with out-of-hours care. METHODS: All patients contacting the service over a designated 24 day period were forwarded a postal questionnaire. Health status was recorded using the Short Form-12 (SF-12) health survey. Patients' satisfaction was measured by using a version of the McKinley questionnaire. RESULTS: The response rate was 55% (531 out of 966). Overall satisfaction levels were high, with 88% of patients rating the service as either excellent or good. Logistic regression, modelling for the simultaneous effects of age, gender, socio-economic status, call outcome and health status on overall satisfaction, found that patients with lower physical and mental health status scores were significantly less likely to be satisfied with their out-of-hours care [odds ratio (OR) 1.04, 95% confidence interval (CI) 1.01-1.07, P = 0.017; and 1.03, 95% CI 1.00-1.06, P = 0.046, respectively]. Patients with higher socio-economic status were also significantly less likely to be satisfied (OR 0.25, 95% CI 0.11-0.55, P = 0.001). Patient's age and gender, and call outcome did not significantly affect overall satisfaction levels. CONCLUSION: Family doctor co-operatives have significantly altered the way out-of-hours care is delivered. Patients with lower health status are significantly less likely to be satisfied with this new form of out-of-hours care. This finding has important implications for the future planning of out-of-hours primary care services.

Adolescent↗
PubMed2002

Reproducibility of the blood lactate threshold, 4 mmol.l(-1) marker, heart rate and ratings of perceived exertion during incremental treadmill exercise in humans.

The aim of this study was to investigate the reproducibility of blood lactate measurements, heart rate (HR) and ratings of perceived exertion (RPE) during treadmill exercise at speeds corresponding to the lactate threshold ( v(Th,la)-) and a fixed blood lactate concentration of 4 mmol.l(-1)( v(la)-(,4)). Possible differences in reproducibility related to fitness levels were also investigated. A group of 20 men [mean (SD)] [age 20.5 (1.4) years] and 16 women [age 21.2 (0.9) years] took part in the study. The subjects performed two identical incremental exercise tests consisting of at least six 4 min stages. Blood lactate concentrations, HR and RPE were recorded at the end of each stage. Limits of agreement (LoA), correlation coefficients and 95% confidence intervals for the mean difference between tests were employed to investigate the level of agreement and reproducibility of blood lactate concentration, HR and RPE. For the group as a whole, the sample correlation coefficient for speed at v(Th,la)- was r=0.88, and was r=0.92 for the speed at v(la)-(,4). At v(Th,la) -, the correlation coefficients for the moderately fit and unfit were r=0.94 and r=0.36, respectively, and at v(la)-(,4) r=0.93 and r=0.68, respectively. The LoA for the moderately fit group indicated that a change of 1.62 km.h(-1) in v(Th,la)- would be necessary to be considered a change in training status. For HR and RPE, relationships between the tests were generally poor. The LoA suggested that changes in scores must be unacceptably large. These findings cast doubt on the sensitivity of testing for change of blood lactate concentration, HR and RPE in this population.

Adult↗
PubMed2001

Modified composite or conventional glass ionomer for band cementation? A comparative clinical trial.

The time to first failure, the position of band failure at deband, and the change in enamel white spot lesions of teeth bonded with a modified composite or a conventional glass ionomer were compared in a randomized half-mouth trial over the full course of orthodontic treatment. One hundred forty band pairs were cemented in 98 subjects. Overall band failure rates of 5% and 2.8% were recorded for the modified composite and the conventional glass ionomer, respectively, with no significant difference found between their times to first band failure. At the end-of-treatment deband, the position of band failure was predominantly at the enamel-cement interface for the modified composite and at the band-cement interface for the conventional glass ionomer (P <.001). A comparison of changes in mean enamel white spot lesion scores during treatment did not reveal significant differences between the cement groups (P =.16).

Adolescent↗
PubMed2000

Tuberculosis in Pakistan: socio-cultural constraints and opportunities in treatment.

This study explores the extent to which factors related to individuals, the care provision process, and the cultural context influence the behaviour of tuberculosis patients attending TB clinics in rural Pakistan, and examines the effects of disease on their personal lives. Thirty-six patients attending three TB treatment clinics were interviewed in depth. These patients were stratified by stage of treatment (treatment proceeding, treatment completed, default), sex and by rural/urban status. Results indicate that the majority of patients were very poor, but nonetheless initially chose to attend private practitioners. Normally their disease was correctly diagnosed as tuberculosis only after repeated visits to a succession of health care providers. Patients' knowledge about their disease was limited, and doctors gave incorrect or only very limited health education. Most patients reported dissatisfaction with care provided. Almost all patients reported problems with access to treatment, both in terms of time and money; this was particularly true of women, whose freedom to travel in Pakistan is limited. Potential causes of default appeared to be more closely linked to deficiencies in treatment provision rather than patients' unwillingness to comply. Largely because of a perception that TB was incurable, respondents were generally unwilling to disclose that they were undergoing or had undergone TB treatment. For reasons related to confidential access to treatment, this could lead to default, perpetuating the perception of incurability, and hence causing a vicious circle. For TB programmes to be successful in Pakistan, it is essential that this circle is broken; and this can only be done through provision of good quality TB care and education to improve the population's understanding that TB can be cured. In addition, patients' unwillingness to disclose to health care providers that they had already received previous treatment meant that many patients were prescribed incorrect treatment regimes, potentially leading to the emergence of drug-resistant TB. In common with other researchers' findings, no clear differences were found between those who had completed treatment and those who had defaulted from treatment. This study was performed to provide information to assist the researchers to design potential TB treatment delivery strategies, and has proved invaluable for this purpose. Strategies based on findings from the study are currently being assessed using a randomised controlled trial.

Adolescent↗
PubMed2000

The effect of amlodipine on respiratory and pulmonary vascular responses to hypoxia in mountaineers.

Calcium antagonists are known to reduce the incidence of high-altitude pulmonary oedema, but the mechanism is unclear. The aim of this study was to examine the effects of the calcium antagonist, amlodipine, on cardiac and respiratory responses in normoxia and hypoxia. Fourteen normal subjects aged 31+/-4 yrs who had climbed to altitudes of 5,000-7,500 m without problems were randomly assigned to a double-blind crossover trial of amlodipine versus placebo, using sea-level inspiratory hypoxia to simulate altitude. Doppler echocardiographic estimates of resting pulmonary haemodynamics and cycle ergometer test results of cardiorespiratory responses to exercise were recorded in normoxia and hypoxia. It was found that, although hypoxic pulmonary vasoconstriction (HPV) was not significantly reduced by amlodipine, the effect of the drug on HPV was inversely related to the serum level of amlodipine. Amlodipine did not alter left ventricular function measured echocardiographically. During exercise, amlodipine increased breathlessness, measured using standard scales, in both normoxia and hypoxia but had no effect on ventilatory variables. It was concluded that amlodipine has the potential to block hypoxic pulmonary vasoconstriction as evidenced by a drug concentration-related decrease in resting tricuspid regurgitation jet velocity without any change in resting myocardial contractility. However, with amlodipine, the subjects felt more breathless during exercise. The reasons for this increase in breathlessness are not clear.

Adult↗
PubMed2000

Risk factors for excess weight gain in children treated for acute lymphoblastic leukaemia.

OBJECTIVE: To test whether excess weight gain in patients treated for childhood acute lymphoblastic leukaemia (ALL) was predictable using patient characteristics at diagnosis. DESIGN AND SUBJECTS: Longitudinal study of changes in body mass index (BMI) in all 98 patients treated in Scotland on treatment protocol MRC UKALL-XI who had reached at least 3y post-diagnosis in first remission. MEASUREMENTS: The influence of the following variables on changes in BMI, expressed as a standard deviation score (SDS), was tested using variable selection techniques and classification and regression trees: BMI SDS at diagnosis; age at diagnosis; gender; socioeconomic status; treatment. RESULTS: Prevalence of obesity (BMI SDS>2.0) was <2% at diagnosis, but increased to 16% at 3y. Gain in BMI SDS was significantly inversely influenced by BMI SDS at diagnosis (P<0.01) and age at diagnosis (P<0.01). CONCLUSION: Obesity is common in ALL by the end of therapy, and is more likely in children who are younger and thinner at diagnosis. Excess weight gain was not readily predictable from routinely collected information available at diagnosis and so all children treated for ALL should be considered 'at risk' of excess weight gain and the target of obesity prevention.

Age Factors↗
PubMed2000

A comparative clinical trial of a compomer and a resin adhesive for orthodontic bonding.

The study aimed to compare the survival time and cariostatic potential of a compomer to that of a resin adhesive when used to bond stainless steel orthodontic brackets to labial segment teeth only. The effect of the patients' sex, age at the start of treatment and presenting malocclusion on bracket survival time was assessed also. Forty-five consecutive patients who attended for fixed appliance therapy were randomly selected. Four hundred twenty-six brackets were bonded (213 with compomer and 213 with resin adhesive) with a split mouth design; the right or left side allocation of compomer in either arch was alternated. Color transparencies of the maxillary incisors, mandibular incisors, or both, and transparencies of the canines, were taken before treatment. At the debond stage, the transparencies were projected (20x) and assessed by an experienced examiner, who used a caries index. The survival time distributions for brackets bonded with each bonding agent were not significantly different (P = .74, paired Prentice-Wilcoxon test; P = .75, Akritas test), with bracket failure rates of 17% and 20% recorded for compomer and resin adhesive, respectively. Neither the patients' sex (P = .85) nor malocclusion (P = .26) appear to affect significantly bracket survival, but patient age was identified as a useful prognostic indicator of bracket survival (P < .001). On average, there was more decalcification related to brackets bonded with resin adhesive than with compomer (P = .0075). Survival time distributions of brackets bonded with compomer or resin adhesive appear comparable, but decalcification was reduced significantly by bonding with compomer.

Adolescent↗
PubMed1999

Genetic and environmental influences in the development of multiple primary melanoma.

OBJECTIVES: To identify risk factors and the prognosis associated with the development of multiple primary melanoma (MPM). DESIGN: Case-comparison studies of subjects with MPM and single primary melanoma. Sequencing of CDKN2A in germline DNA. SETTING: Population-based study of patients with invasive melanoma in Scotland between 1979 and 1996. PATIENTS: For mortality studies, 108 patients with MPM and 216 single melanoma controls matched for age, sex, site, and tumor thickness. For risk factor studies, 48 patients with MPM and 48 single melanoma controls matched as above. For CDKN2A analysis, a sample of 23 subjects with MPM. RESULTS: The development of MPM was found not to be an independent prognostic factor. The risk of MPM was greatest in those with a family history of melanoma, with large numbers of benign nevi, and the presence of clinically or histologically atypical nevi. Germline mutations of CDKN2A were present in 6 of 23 patients with MPM and in 5 cases consisted of the base pair substitution Met53Ile. CONCLUSIONS: The importance of MPM should be addressed in melanoma follow-up protocols. Those patients at greatest risk can be identified by a family history of melanoma and their mole pattern. Germline mutations in CDKN2A occur in both familial and sporadic MPM and further studies are required to determine the value of analysis of this gene in melanoma surveillance. Patients should be informed that the development of MPM does not adversely affect their prognosis.

Disease Susceptibility↗
PubMed1999

Echocardiographic determination of risk area size in a murine model of myocardial ischemia.

Genetically altered mice are useful to understand cardiac physiology. Myocardial contrast echocardiography (MCE) assesses myocardial perfusion in humans. We hypothesized it could evaluate murine myocardial perfusion before and after acute coronary ligation. MCE was performed before and after this experimental myocardial infarction (MI) in anesthetized mice by intravenous injection of contrast microbubbles and transthoracic echo imaging. Time-video intensity curves were obtained for the anterior, lateral, and septal myocardial walls. After MI, MCE defects were compared with the area of no perfusion measured by Evans blue staining. In healthy animals, intramyocardial contrast was visualized in all the cardiac walls. The anterior wall had a higher baseline video intensity (53 +/- 17 arbitrary units) than the lateral (34 +/- 13) and septal (27 +/- 13) walls (P < 0.001) and a lower increase in video intensity after contrast injection [50 +/- 17 vs. 60 +/- 24 (lateral) and 65 +/- 29 (septum), P < 0.01]. After MI, left ventricular (LV) dimensions were enlarged, and the shortening fraction was decreased. A perfusion defect was imaged with MCE in every mouse, with a correlation between MCE perfusion defect size (35 +/- 13%) and the nonperfused area by Evans blue (37 +/- 16%, y = 0.77x + 6.1, r = 0.93, P < 0. 001). Transthoracic MCE is feasible in the mouse and can accurately detect coronary occlusions and quantitate nonperfused myocardium.

Animals↗
PubMed1999

Correlation of CT findings with clinical evaluations in 261 patients with symptomatic bronchiectasis.

OBJECTIVE: In a multicenter study, we evaluated the relationships between the extent and severity of bronchiectasis on CT and clinical symptoms, spirometric abnormality, and sputum characteristics. SUBJECTS AND METHODS: The study population included 261 patients with symptomatic, physiologically significant bronchiectasis, who were enrolled in another study evaluating the clinical efficacy of deoxyribonudease in treatment of bronchiectasis. Patients with cystic fibrosis, allergic bronchopulmonary aspergillosis, and fungal or mycobacterial infection were excluded. In addition to high-resolution CT scanning, all patients underwent clinical evaluation, spirometry, and sputum culture. CT features scored by consensus of two observers included the extent of bronchiectasis, type of bronchiectasis (cylindric, varicose, or cystic), extent of mucoid impaction, and degree of bronchial wall thickening. RESULTS: Scores for the severity and extent of bronchiectasis correlated with the forced expiratory volume in 1 sec (FEV1) (r = -.362, p < .0001) and with the forced vital capacity (FVC) (r = -.362, p < .0001). Scores for bronchial wall thickening correlated with the FEV1 (r = -.367, p < .0001) and FVC (r = -.239, p < .001). Patients with cystic bronchiectasis were significantly more likely to grow Pseudomonas from their sputa and to have purulent sputa than were patients with cylindric or varicose bronchiectasis. Patients with cystic bronchiectasis had significantly lower FEV1 and FVC values than did patients with cylindric or varicose bronchiectasis. CONCLUSION: In this patient population, we found weak but significant correlations between the degree of morphologic abnormality on CT and the extent of physiologic impairment. Cystic bronchiectasis was associated with sputum purulence and with the growth of Pseudomonas. CT classification of the type of bronchiectasis may be useful as an index of severity of disease.

Bronchi↗
PubMed1998

A novel role for Rab5-GDI in ligand sequestration into clathrin-coated pits.

BACKGROUND: Clathrin-coated pits are formed at the plasma membrane by the assembly of the coat components, namely clathrin and adaptors from the cytosol. Little is known about the regulation and mechanism of this assembly process. RESULTS: We have used an in vitro assay for clathrin-coated pit assembly to identify a novel component required for the invagination of newly formed coated pits. We have purified this cytosolic component and shown it to be a complex of Rab5 and GDI (guanine-nucleotide dissociation inhibitor), that was previously demonstrated to be involved in downstream processing of endocytic vesicles. Using a combination of quantitative electron microscopy and in vitro endocytosis assays, we have demonstrated that although coat proteins and ATP are sufficient to increase the number of new coated pits at the cell surface in permeabilised cells, the Rab5-GDI complex is required for ligand sequestration into clathrin-coated pits. CONCLUSIONS: We have identified Rab5 as a critical cytosolic component required for clathrin-coated pit function. Given the well-established role of Rab5 in the fusion of endocytic vesicles with endosomes, our results suggest that recruitment of essential components of the targeting and fusion machinery is coupled to the formation of functional transport vesicles.

Amino Acid Sequence↗