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Biomedical subjects

J Stevens

Publications and source records attributed to J Stevens.

At least 37 records · Page 2Linked to original sources
PubMed2001

Sensitivity and specificity of anthropometrics for the prediction of diabetes in a biracial cohort.

OBJECTIVE: To evaluate the ability of body mass index, waist circumference, waist-to-hip ratio, and combinations of these variables to discriminate individuals who will develop diabetes in adulthood. RESEARCH METHODS AND PROCEDURES: Data were from 45- to 64-year-old men and women who were members of the Atherosclerosis Risk in Communities cohort. The analysis sample consisted of 12,814 African American and white participants who were free of diabetes at baseline. Body mass index, waist circumference, waist-to-hip ratio, and diabetes incidence (defined as one glucose measure > or =126 mg/dL after fasting for at least 8 hours, one nonfasting glucose measure > or =200 mg/dL, and self-report of diabetes or report of taking medication for diabetes). RESULTS: 1515 new cases of diabetes were identified over the 9-year follow-up. Areas under receiver operating characteristic curves ranged from 0.66 to 0.73 for single measures. The curves were smooth, with no indication of a threshold. Waist tended to have the highest receiver operating characteristic statistic in all groups, but differences were small. DISCUSSION: The three anthropometric indices tested were approximately equivalent in their ability to predict diabetes. Sensitivity and specificities differed among ethnic and gender groups.

Anthropometry↗
PubMed2001

The influence of intraperitoneal bupivacaine on pain following major laparoscopic gynaecological procedures.

We present the results of a randomised, double-blind controlled trial to determine the effect of adding bupivacaine to intraperitoneal Hartmann's solution, used to reduce the incidence of postoperative adhesions, on postoperative pain and on analgesic consumption in patients presenting for major laparoscopic gynaecological procedures. Fifty-six women were studied and postoperative analgesic requirements and visual analogue scores were used to assess the pain experienced by the treatment group when compared with the control group. There was no statistical difference in the pain scores between the two groups at any time during the study period (Student's t-test; p = 0.29-0.74) nor was there any difference in analgesic consumption (Mann-Whitney U-test; p = 0.34-0.79).

Adult↗
PubMed2001

State of the art neonatal hearing screening with auditory brainstem response.

The purpose of this paper is to briefly review some of the aspects of the auditory brainstem response (ABR) that are important in its use as a method of screening and assessing hearing in the neonate. The paper starts by considering the technical limitations of click ABR and explores the alternative electrophysiological methods. It then considers where ABR is required in the screening of neonates. The role of bone conduction ABR in estimating the conductive component of any hearing loss is discussed. Finally, the ability of the neonatal ABR to predict the long-term audiometric outcome of permanently hearing-impaired children is considered.

Evoked Potentials, Auditory, Brain Stem↗
PubMed2001

Performance of neonatal and infant hearing screens: sensitivity and specificity.

The terms 'sensitivity' and 'specificity' are defined and some of the factors that determine their values are discussed in the context of screening for permanent childhood hearing loss. There is a need to distinguish between the values observed in 'simple experiments' and those that may be obtained under more realistic 'field' conditions. It is not feasible to give a meta-analytic overview of published data because of the variety of methods and objectives used in those studies published in the literature. However, a qualitative synthesis of the data is possible. This suggests that most proposed neonatal hearing screening tests, when implemented in accordance with a programme of quality assurance, can be reasonably accurate at a modest cost. However, the optimal combination of tests and test parameters for given populations has not yet been fully researched. The infant distraction test screen has a lower sensitivity than neonatal hearing screening tests, particularly for moderate impairments, accompanied by a fairly low specificity.

Child Health Services↗
PubMed2001

Patterns of long-term change in body composition are associated with diet, activity, income and urban residence among older adults in China.

Studies describing patterns of long-term change in body composition are lacking. Using longitudinal data on 608 healthy, nonobese Chinese (aged 50-70 y) from the 1993 and 1997 China Health and Nutrition Surveys, this article describes the prevalence, sociodemographic and lifestyle correlates of patterns of long-term change in midarm muscle area (MAMA) and body fat (waist circumference). All patterns of change (loss, maintenance [Delta < 1.3 cm(2)], or gain of MAMA with concurrent loss, maintenance [Delta < 2 cm(2)] or gain of body fat), were observed for this sample. After controlling for sex, baseline age, urban residence, height, weight, income, MAMA, waist circumference, smoking status, activity level, mean daily energy and protein intakes (from three 24-h recalls), and change in height, it was determined that subjects who lost both arm muscle and body fat were distinguished from subjects who lost arm muscle but gained body fat by lower income and energy intake at baseline. Although protein intakes at baseline did not differ between the groups that lost arm muscle, protein intakes were significantly higher for subjects who gained both muscle and fat. Patterns of change involving gains in arm muscle were associated with increased protein intake, urban residence, as well as moderate or heavy levels of physical activity at baseline. Variation in protein intake, physical activity, and urban residence also differentiated between the groups that gained fat. Patterns of age-related change in body composition appear associated with modifiable variables, including income, urban residence, activity and protein and energy intake.

Aged↗
PubMed2001

The use of electrical stimulation to increase quadriceps femoris muscle force in an elderly patient following a total knee arthroplasty.

BACKGROUND AND PURPOSE: Persistent residual quadriceps femoris muscle force deficits after total knee arthroplasty (TKA) are commonly reported and can prevent patients from returning quickly and fully to functional activities. Neuromuscular electrical stimulation offers a potentially more effective means of increasing muscle force than current rehabilitation protocols. CASE DESCRIPTION: The patient was a 66-year-old man. Neuromuscular electrical stimulation for increasing quadriceps femoris muscle force was initiated 3 weeks after TKA for 11 sessions to supplement stretching exercises and a high-intensity volitional strengthening program. OUTCOME: The patient's isometric quadriceps femoris muscle force increased from 50% (involved/uninvolved) at 3 weeks after surgery to 86% at 8 weeks after surgery. A concurrent increase in his uninvolved quadriceps femoris muscle force concealed the patient's true increase in his involved quadriceps femoris muscle force in a side-to-side comparison. The patient's final involved quadriceps femoris muscle force (10 weeks after surgery) was 93% of the initial uninvolved quadriceps femoris muscle force. DISCUSSION: Our patient was able to return to independent activities of daily living and recreational activities, with force gains that surpassed those reported in the literature.

Aged↗
PubMed2001

Arterial distensibility and physical activity in the ARIC study.

PURPOSE: Arterial distensibility decreases with age. This decrease may be associated with the initiation and/or progression of hypertension and atherosclerosis and may be attenuated by positive lifestyle habits, including habitual physical activity. We tested the hypothesis that self-reported sport, leisure, and work physical activity is associated with greater arterial distensibility (i.e., carotid artery pulsatile diameter changes). METHODS: The Atherosclerosis Risk in Communities (ARIC) study assessed left common carotid arterial diameters and intimal-medial wall thickness (IMT) using B-mode ultrasound techniques, in 10,644 African-American and white men and women aged 45-64 yr and free of cardiovascular disease. RESULTS: Work activity, but not sports or leisure activity, was weakly associated with greater arterial distensibility in an ANCOVA model adjusted for blood pressure and other covariates (diastolic arterial diameter, pulse pressure, pulse pressure squared, age, race, sex, smoking, dietary fat intake, height, education, and clinical center) (P for linear trend = 0.03). Vigorous sports activity was weakly positively associated with arterial distensibility (arterial diameter change (mean +/- SE in mm) 0.42 +/- 0.004 vs 0.41 +/- 0.002 for the 12.7% of participants reporting any vs no vigorous activity, P = 0.02), and this association was not attenuated by adjustment for IMT, body mass index, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, or diabetes. Repeated analyses with traditional arterial stiffness indices showed similar findings for vigorous but not work activity. CONCLUSION: In contrast to several smaller studies, these findings do not support the hypothesis that habitual physical activity has a strong, consistent positive effect on arterial distensibility.

Arteries↗
PubMed2001

Bleomycin upregulates gene expression of angiotensin-converting enzyme via mitogen-activated protein kinase and early growth response 1 transcription factor.

Pulmonary fibrosis is a progressive disorder characterized by the loss of alveolar architecture through epithelial and endothelial cell apoptosis and fibroblast proliferation. Recent studies showed that angiotensin-converting enzyme (ACE) activity is increased in fibrotic tissues, and ACE inhibitors administered in vivo ameliorate fibrosis, suggesting that ACE may play a critical role. However, the regulation of ACE expression is not well understood. In the present study, we demonstrate that bleomycin, a chemotherapeutic agent which induces pulmonary fibrosis in animals and humans, increases gene expression of ACE. Treatment of primary bovine pulmonary artery endothelial cells with 0.1 to 1.0 microg/ml bleomycin increased ACE enzymatic activity and ACE mRNA, as monitored by hippuryl-L-histidyl-L-leucine assay and competitive quantitative reverse transcriptase polymerase chain reaction (RT-PCR), respectively. Luciferase reporter constructs showed that upregulation of ACE transcription by bleomycin is mediated through element(s) in the 97-bp ACE promoter. Bleomycin activated p42/p44 mitogen-activated protein kinase (MAPK) and induced nuclear translocation and activation of the early growth response (Egr)-1 transcription factor, a factor previously shown to positively regulate ACE expression. The MAPK kinase1/2 (MEK1/2) inhibitor U0126 blocked MAPK and Egr-1 activation by bleomycin, suggesting that Egr-1 activation is MAPK dependent. These data provide the first evidence that bleomycin activates ACE gene expression through the MAPK pathway and Egr-1.

Animals↗
PubMed2001

The possible effects on health, comfort and safety of aircraft cabin environments.

A consultation was undertaken to investigate the views and concerns of stakeholders in the aircraft industry about the possible harmful effects on personal health, comfort and safety of aircraft cabin environments. Stakeholders were identified from a variety of sources including Government agencies, the Internet, House of Lords inquiry, and suggestions of interviewees. They represented: aircraft crews, aircraft constructors and engineers, government departments and authorities, holiday/flight companies, insurance companies, non-governmental organisations, occupational health physicians, passenger representatives, and independent researchers and consultants. Eighty-seven were contacted of which 57 were interviewed over the telephone using a semi-structured questionnaire. Their concerns were transcribed into a standard format and analysed qualitatively. Key stakeholders, along with Government officials, were invited to a workshop to discuss and prioritize the issues raised during the interviews. The main concerns expressed by the participants fell into five main areas: deep vein thrombosis, air quality, infection, cosmic radiation, and jet lag and work patterns. In addition, a number of safety concerns were raised as well as comments on the provision of appropriate advice to passengers. It was generally felt that further research was required on each of these subjects, as well as an improvement in the quality, quantity and availability of information provided for passengers prior to boarding a flight.

Air Pollution, Indoor↗
PubMed2001

Clinical and radiological correlates of severity and surgery-related outcome in cervical spondylosis.

OBJECT: The aim of this study was to determine if radiological features could be used to predict outcome in patients with cervical spondylotic myelopathy (CSM). METHODS: The authors studied 69 patients consecutively referred to The National Hospital, Queen Square, for decompressive surgery. Data obtained from preoperative cervical spine magnetic resonance (MR) imaging studies were each analyzed on two separate occasions by two blinded radiologists. The parameters determined were signal change and the presence and severity of compression. Clinical outcome was determined by pre- and postoperative timed walks, as well as by evaluation of myelopathy disability index scores, Ranawat classification, and Nurick grades. There was good inter- and intraobserver reliability for determination of radiological data. A significant relationship was found between MR imaging signal change and surgery-related outcome, as reflected by improvement in walking parameters; however, this was confounded by the fact that signal change also related to preoperative walking parameters, and those patients for whom preoperative walking function was worse experienced greater functional improvement in walking postoperatively. The relationships between ambulatory-related data and severity or extent of spinal cord compression were less marked. CONCLUSIONS: Cervical cord compression and intrinsic MR imaging signal change correlate with clinical severity, and, in this population, the presence of signal change was correlated with better surgery-related outcome. However, confounding factors and the lack of strong correlation indicate that these radiological measurements are insufficient to be used as a reliable tool for predicting surgery-related benefits in individual patients.

Aged↗
PubMed2001

Generating theory from the client's experience of same day laparoscopic sterilisation.

A grounded theory methodology was used to generate theory about the experiences of women undergoing laparoscopic sterilisation in a day surgery unit. Theories were developed on the role of client education in relieving anxiety, and the importance of privacy in all stages of client care. The grounded theory approach offered a client-centered model for day surgery planning.

Adaptation, Psychological↗
PubMed2000

Peptide specificity of RT1-A1(c), an inhibitory rat major histocompatibility complex class I natural killer cell ligand.

The rat major histocompatibility complex class Ia allelomorph RT1-A1(c) is a potent ligand for the recently identified inhibitory rLy-49 receptor, STOK-2. With the ultimate objective of studying the interactions of these molecules using structural and functional methods, we undertook a detailed study of its peptide specificity. The study revealed that designing an "ideal peptide" by choosing the most abundant residues in the "binding motif" obtained by pool sequencing does not necessarily yield an optimal binding peptide. For RT1-A1(c), as many as four positions, P2, P4, P5, and P9, were detected as putative anchors. Since this molecule displays a preference for highly hydrophobic peptides, we tested binding of peptides derived from the known leader peptide sequences of other rat histocompatibility complex class I molecules. One such peptide, found to bind well, requiring 1.6 microm peptide to achieve 50% stabilization, was searched for in vivo. Natural RT1-A1(c) binding peptides were purified from rat splenocytes and characterized by mass spectrometry using a combined matrix-assisted laser desorption ionization/time-of-flight and quadrupole time-of-flight approach. Results showed that the signal sequence-derived peptide was not detectable in the purified peptide pool, which was composed of a complex spectrum of peptides. Seven of these self-peptides were successfully sequenced.

Animals↗
PubMed2000

Structure and sequence variation of the trypanosome spliced leader transcript.

We have assessed the potential of using the spliced leader (SL) or mini-exon gene as a marker for molecular phylogenetic analysis of genus Trypanosoma. A total of 27 trypanosome sequences were compared, 18 of these being newly reported. In contrast to genus Leishmania, we found the non-transcribed spacer region of the SL locus in trypanosomes to be far too variable for informative comparison of all but the most closely related species. At the other extreme, the short (39 nt) SL exon was usually completely conserved and hence uninformative. The SL RNA showed variation in both length (97-152 nt) and sequence among different trypanosome species, with most variation occurring in stem-loop II. Consequently, this region could not be aligned with confidence in multiple sequence alignment, severely reducing the number of phylogenetically informative nucleotide positions. In computer simulation, most of the SL RNAs readily folded into the 3 stem-loop secondary structure predicted previously, but again stem-loop II was highly variable. No obvious correlation could be seen between the length of this stem-loop and trypanosome biology. We conclude that the SL repeat is not an informative phylogenetic marker for long range evolutionary studies of genus Trypanosoma.

Animals↗
PubMed2000

Imaging and radiological-pathological correlation in histologically proven cases of focal cortical dysplasia and other glial and neuronoglial malformative lesions in adults.

Focal cortical dysplasia (FCD) is a pathological entity first described in 1971. Other more subtle cortical malformations found in patients with epilepsy include microdysgenesis (MD), and glioneuronal hamartias. Although these glial and neuronoglial malformations have distinct histological features, there is terminological confusion in the radiological literature. Few cases have been reported in adults with both imaging and histology. We address these issues, giving a radiological-pathological correlation of histologically proven cortical malformations in adults. We describe clinical, radiological and histological features of 12 cases (five FCD, five MD with glioneuronal hamartias, and two hamartomas), unassociated with other conditions, and discuss them in the light of the literature. FCD is usually seen on MRI as cortical thickening, with or without signal change, which may extend into the adjacent white matter. On histology, abnormal neurons and/or glial cells, blurring of the grey-white matter interface, myelin pallor, demyelination, and gliosis may be found. Glioneuronal hamartias and hamartomas usually appear as complex masses on MRI. FCD and hamartias may be associated, and a combination of imaging findings may be seen on MRI. Atrophy of the ipsilateral hippocampus may be present on MRI in patients with hamartias, and minor cell loss on histology, but not definitive hippocampal sclerosis. Although the imaging findings of cortical malformations are protean, some characteristic MRI features, with histological correlates, may be found. The relevance of most of these observations remains unclear.

Adult↗