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Biomedical subjects

J Walker

Publications and source records attributed to J Walker.

At least 73 records · Page 4Linked to original sources
PubMed2001

The 2-minute walk test as a measure of functional improvement in persons with lower limb amputation.

OBJECTIVE: To determine the construct validity and responsiveness of the 2-minute walk test as a measure of function in individuals with lower extremity amputation. DESIGN: The distances walked in 2 minutes were compared with the results on the physical functioning subscale of the Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36) and the Houghton Scale. SETTING: Regional amputee rehabilitation program. PATIENTS: Retrospective data from 290 patients (mean age, 66yr) with unilateral transtibial, unilateral transfemoral, or bilateral amputations. INTERVENTION: Repeated testing. MAIN OUTCOME MEASURES: Distance walked in 2 minutes, SF-36 (aggregated into physical and mental composite scores), and the Houghton score. We also examined the change in the distance before and after a rehabilitation program. RESULTS: The distance walked in 2 minutes showed a weak correlation with the physical functioning subscale of the SF-36 (r = .22, p = .008) and a moderate correlation with the total Houghton score at discharge from rehabilitation (r = .493, p <or= .001). The correlation between distance walked in 2 minutes and SF-36 physical functioning subscale at follow-up was moderate (r = .479, p < .001). There was a significant improvement in distance walked in 2 minutes at discharge and follow-up compared with baseline (mean change +/- standard deviation at discharge, 13.6 +/- 19.9m; at follow-up, 41.2 +/- 34m, p < .001). CONCLUSION: The 2-minute walk test was responsive to change with rehabilitation in persons with lower extremity amputation. In addition, the 2-minute walk test showed adequate correlation with measures of physical functioning and prosthetic use in this population.

Aged↗
PubMed2001

Drugs of abuse in pregnancy.

Care for the drug-using pregnant woman is being increasingly recognized as part of the obstetrician's role. There is great potential for improvement in provision of services for this group of women, partly because traditionally our antenatal clinics have not been perceived as being conducive to disclosure regarding drug use, but also because hard data and, indeed, randomized controlled trials on the subject, are scarce.From the little evidence available, and from our own experience in this area, we have attempted to outline the main problems encountered in the antenatal, intrapartum and postnatal periods with each of the main drugs of abuse and the management thereof. It is important to note that we include cigarette smoking and alcohol, probably the most commonly used drugs in pregnancy, and recognize that the picture is wider than the stereotypical emaciated intravenous heroin addict. Where possible, evidence from trial data is included, but much of the what is quoted is descriptive from personal experience from ourselves and others working in the field.

Alcohol Drinking↗
PubMed2001

Colorectal carcinoma in children and adolescents--a report of seven cases.

Between 1981 and 1997 seven children and adolescents (5 boys and 2 girls) were treated for colorectal carcinomas in two paediatric centres. The case notes of the patients were studied to determine the presentation, clinical findings, prognosis and the differences of colorectal carcinomas in the young patients compared to adults. Carcinoma of the colon and rectum is uncommon in this age group and has a poor prognosis. The age range was 9 - 15 years, mean age 11.8 years. All segments of the large bowel were represented as sites of the primary tumour. Vague abdominal pain, vomiting and weight loss were the commonest presenting symptoms. The duration of symptoms varied from one month to twelve months (median: four months). Contrast enema was the most useful diagnostic investigation. Five patients had Dukes' stage C and two had Dukes' stage D tumour. Mucin-secreting adenocarcinoma was the commonest histological diagnosis. Five patients had complete resection, two had palliative procedures. Post-operative chemotherapy was given to six patients and two had post-operative radiotherapy.

Adenocarcinoma↗
PubMed2001

Ultrastructural and histological effects of exposure to CEES or heat in a human epidermal model.

Ultrastructural and terminal deoxynucleotidyl transferase nick end labeling (TUNEL) studies were conducted to compare mechanisms of 2-chloroethyl ethyl sulfide (CEES) and heat-induced injury to EpiDerm. Twenty-two hours after 2-h exposure to the monofunctional alkylating agent CEES, budding of cytoplasm, clumping of nuclear chromatin, disintegration of nuclear membranes and cytoplasmic structures, and cytoplasmic vacuolization were detected, especially in the basal cells near the pseudobasement membrane. TUNEL techniques revealed DNA fragmentation distinct from that normally associated with terminal keratinocyte differentiation. Similar evaluations 22.5 h after 90 min exposure of EpiDerm to elevated temperature (45 degrees C) produced a different pattern of cell damage. Swelling of intercellular spaces, extensive cytoplasmic vacuolization, disruption of normal nuclear shape, reduced cell membrane integrity, and release of cellular material in the basal region characterized heat injury. Heat did not alter the DNA fragmentation normally associated with keratinocyte maturation. These data suggest that CEES elicited an apoptotic mechanism of cell death with features of terminal differentiation such as nuclear membrane disintegration and loss of cytoplasmic structures. Heat, alternatively, produced changes more typical of oncotic necrosis.

Apoptosis↗
PubMed2001

Rate of injection through whitacre needles affects distribution of spinal anaesthesia.

A prospective, randomized, double-blind study was performed to investigate whether altering the rate of injection of local anaesthetic through a Whitacre needle had any effect on the spinal block achieved. Twenty patients scheduled for elective urological surgery under spinal anaesthesia received an injection of 3 ml of 0.5% plain bupivacaine either by hand (fast) over 10 s (18 ml min(-1)) or by infusion pump (slow) over 3 min (1 ml min(-1)). All patients were in the sitting position both during insertion of the spinal needle and for 3 min after the start of spinal injection, and they then changed to the supine position. The slow injection group achieved peak sensory block earlier, after a median interval of 20 (95% confidence interval 12.5-30) min vs 30 (22.5-45) min (P<0.05) for the fast group. The level of peak sensory block was similar: T3.5 (T2-T4.5) vs T4 (T1.5-T6.5). The time to lowest mean arterial pressure occurred earlier in the slow group, at 10 (8 to 18) vs 20 (15-31) min (P<0.05). Duration of the motor block was shorter in the slow group: 180 (152-242) vs 270 (225-300). We conclude that a slow spinal injection of plain bupivacaine results in a block of more rapid onset and recovery.

Aged↗
PubMed2001

Developing a shared leadership model at the unit level.

As the nursing profession again faces a serious shortage, many are seeking ways to attract and retain talented people in the nursing profession. Creating both empowering and healthy work environments is a way to achieve this goal. Shared leadership is a nursing management model that supports staff nurses in extending their influence about decisions that affect their practice, work environment, professional development, and self-fulfillment. It is a way to strengthen continuous learning and enhance relationships, which are the foundation upon which nurses can develop a new type of relationship with management and with each other.

Communication↗
PubMed2001

Comparison of transvaginal ultrasound, saline infusion sonography and hysteroscopy to investigate postmenopausal bleeding and unscheduled bleeding on HRT.

A study was conducted to compare transvaginal ultrasound (TVS), saline infusion sonography (SIS) and outpatient hysteroscopy for examining the uterine cavity in women with postmenopausal bleeding and unscheduled bleeding on hormone replacement therapy (HRT). Fourty Subjects agreed to undergo TVS, SIS and hysteroscopy in addition to endometrial sampling. The abnormalities detected by each imaging method were recorded together with the discomfort (visual analogue scale). Thirty women completed all three imaging procedures. In 18 cases TVS suggested an abnormal cavity. SIS and hysteroscopy were of similar efficacy in clarifying the nature of this, and confirmed an abnormality in 12 cases (40%). TVS was significantly less painful than the other procedures (p < 0.001). SIS and hysteroscopy were associated with pain scores similar to endometrial sampling. These findings justify the need for a large randomised trial of TVS, SIS, hysteroscopy and endometrial sampling, in order to develop the most appropriate strategy for investigating postmenopausal bleeding and unscheduled bleeding on HRT.

Endometrium↗
PubMed2001

Modulation of fibrin cofactor activity in plasminogen activation.

Fibrin is a cofactor for the formation of plasmin from plasminogen as catalyzed by tissue plasminogen activator. Initial cleavages of fibrin by plasmin upregulates the cofactor activity of fibrin by exposing carboxyl terminal lysine residues. This effect is eliminated by a carboxypeptidase B-like enzyme generated from the precursor, thrombin activatable fibrinolysis inhibitor (TAFI) that is generated by thrombin during the formation of fibrin. Thus, TAFI and its activation to TAFIa create a link between the coagulation and fibrinolytic cascade, such that activation of the former suppresses the latter. Complete solubilization of fibrin results in a family of very large fibrin degradation products. These also have very substantial tissue plasminogen activator cofactor activity that is very highly downregulated by TAFIa.

Carboxypeptidase B2↗
PubMed2001

Coverage of neonatal screening: failure of coverage or failure of information system.

OBJECTIVES: To evaluate neonatal screening coverage using data routinely collected on the laboratory computer. SUBJECTS: 90 850 births in 14 North East Thames community provider districts over a 21 month period. METHODS: Births notified to local child health computers are electronically copied to the neonatal laboratory computer system, and incoming Guthrie cards are matched against these birth records before testing. The computer records for the study period were processed to estimate the coverage of the screening programme. RESULTS: Out of an estimated 90 850 births notified to child health computers, all but 746 (0.82%) appeared to have been screened or could be otherwise accounted for (0.14% in non-metropolitan districts, 0.39% in suburban districts, and 1.68% in inner city districts). A further 893 resident infants had been tested, but could not be matched to the list of notified resident births. The calculated programme coverage already exceeds the 99.5% National Audit Programme standard in 7/14 districts. Elsewhere it is not clear whether it is coverage or recording of coverage that is low. CONCLUSION: Previous reports of low coverage may have been exaggerated. High coverage can be shown using routine information systems. Design of information systems that deliver accurate measures of coverage would be more useful than comparison of inadequately measured coverage with a national standard. The new NHS number project will create an opportunity to achieve this.

Birth Certificates↗
PubMed2001

Comparative accuracy of cardiovascular risk prediction methods in primary care patients.

OBJECTIVE: To compare the relative accuracy of cardiovascular disease risk prediction methods based on equations derived from the Framingham heart study. DESIGN: Risk factor data were collected prospectively from subjects being evaluated by their primary care physicians for prevention of cardiovascular disease. Projected cardiovascular risks were calculated for each patient with the Framingham equations, and also estimated from the risk tables and charts based on the same equations. SETTING: 12 primary care practices (46 doctors) in Birmingham. PATIENTS: 691 subjects aged 30-70 years. MAIN OUTCOME MEASURES: Sensitivity, specificity, and positive and negative predictive values of the Framingham based risk tables and charts for treatment thresholds based on projected cardiovascular disease or coronary heart disease risk. RESULTS: 59 subjects (8.5%) had projected 10 year coronary heart disease risks >/= 30%, and 291 (42.1%) had risks >/= 15%. At equivalent projected risk levels (10 year coronary heart disease >/= 30% and five year cardiovascular disease >/= 20%), the original Sheffield tables and those from New Zealand have the same sensitivities (40.0%, 95% confidence interval (CI) 26.6% to 57.8% v 41.2%, 95% CI 28.7% to 57. 3%) and specificities (98.6%, 95% CI 97.2% to 99.3% v 99.7%, 95% CI 98.8% to 100%). Modifications to the Sheffield tables improve sensitivity (91.4%, 95% CI 81.3% to 96.9%) but reduce specificity (95.8%, 95% CI 93.9% to 97.3%). The revised joint British recommendations' charts have high specificity (98.7%, 95% CI 97.5% to 99.5%) and good sensitivity (84.7%, 95% CI 71.0% to 93.0%). CONCLUSIONS: The revised joint British recommendations charts appear to have the best combination of sensitivity and specificity for use in primary care patients.

Adult↗
PubMed2001

Regulation of proximal tubule sodium/hydrogen antiporter with chronic volume contraction.

We developed a model of volume contraction in rabbits by using a furosemide/low-salt diet to follow changes, if any, in proximal tubule Na+/H+ exchanger 3 (NHE3) mRNA and brush-border protein. The rabbits' plasma renin, aldosterone, and urine sodium content confirmed the volume-contracted state. RNase protection assays demonstrated increases in treated-animal NHE3 mRNA as a percentage of control with 172 +/- 23, 154 +/- 15, 153 +/- 14, and 141 +/- 7 (SE) % (P < 0.05) at 1, 5, 10, and 31 days, respectively. Western analysis of brush-border membrane with NHE3 antibody revealed increased immunoreactivity in treated animals as a percentage of control with 120 +/- 30, 190 +/- 59, 307 +/- 72, and 427 +/- 41% (P < 0.05) at 1, 5, 10, and 31 days, respectively. There was no significant difference in serum potassium, bicarbonate, and cortisol in control vs. experimental animals. These data suggest that there is chronic upregulation of NHE3 in the volume-contracted state.

Animals↗
PubMed2001

The effect of nuclear medicine telediagnosis on diagnostic pathways and management in rural and remote regions of Western Australia.

Limited accessibility to certain medical imaging services in regional and rural centres has led to the use of alternative modalities, which may not be best practice or which require patients to travel considerable distances for diagnosis. Data collected over three years were examined to determine the clinical effect of nuclear medicine teleradiology (NMT) and its effect on diagnostic patterns for the investigation of cardiovascular disease, radio-occult musculoskeletal injury and oncology. In comparison with two other rural, non-NMT areas of similar demographic profile, there was a significant shift in the delivery of care in terms of diagnostic work-up. NMT input led to the detection of disease and a change to therapeutic management in 122 cases and eliminated the need to transfer patients to another facility for unnecessary and expensive examinations in 38 cases. While NMT is more costly than conventional nuclear medicine services, it permits faster access to specialist consultation, provides for better management and is likely to reduce overall health costs by reducing the volume of inappropriate tests and treatment practice.

Bone Neoplasms↗
PubMed2001

Satisfaction with innovative community and university health clinic programs for groups of traditionally underserved individuals with HIV/AIDS: empirical models.

As the demographics of the populations of affected individuals have changed, systems of care have needed to adapt to be responsive to client needs. This article examines client satisfaction data from seven national demonstration projects funded to enroll individuals from traditionally underserved groups and help them access services using different strategies. Data on client satisfaction ratings were related to indicators of traditionally underserved status, including demographic characteristics, behaviors, and other risk factors using the data modeling method of Exhaustive CHAID (Chi-squared Automatic Interaction Detector). Client groups that were most likely to experience relatively higher and lower levels of satisfaction with services are identified. Overall, all client groups were highly satisfied with the innovative HIV/AIDS services received. The findings illustrate the success of these innovative HIV care models in being responsive and sensitive to the needs of their target populations.

Adult↗
PubMed2001

HbA(1c) levels are genetically determined even in type 1 diabetes: evidence from healthy and diabetic twins.

HbA(1c), a measure of blood glucose regulation, reflects glucose levels in the preceding months. In diabetes, HbA(1c) levels predict the risk of microvascular complications. The aim of this study was to determine whether genetic factors could influence HbA(1c) levels in normal subjects and type 1 diabetic patients. We performed a classical twin study of HbA(1c) in healthy nondiabetic female twins and 42 monozygotic (MZ) and 47 dizygotic (DZ) pairs. Interclass correlations (r) were higher in MZ (r = 0.77) compared with DZ (r = 0.53) twin pairs, suggesting a substantial genetic effect; this was confirmed by quantitative genetic model fitting. Additive genetic effects (heritability) explained 62% (95% CI 47-75) of population variance in HbA(1c); the remainder was attributable to the influence of unique environment (23% [15-36]) and age (14% [5-28]). Multivariate modeling showed that genetic factors also have a substantial influence on fasting glucose levels (51%). However, HbA(1c) heritability could not be explained by genes in common with fasting glucose. In the patients with type 1 diabetes, HbA(1c) levels were correlated in 33 MZ twins concordant for diabetes (r = 0.68; P < 0.001) but also in 45 MZ twins discordant for the disease (r = 0.52; P < 0.001). These significant correlations for HbA(1c) in both concordant and discordant pairs indicate a diabetes-independent familial effect. Thus, HbA(1c) levels are largely genetically determined and independent of the genes influencing fasting glucose. Even in type 1 diabetes, familial (i.e., diabetes-independent) factors influence protein glycation, implying that familial factors may explain, in part, the risk for microvascular complications, as indicated by high HbA(1c) levels.

Adult↗
PubMed2001

Vaccination of boars with a GnRH vaccine (Improvac) eliminates boar taint and increases growth performance.

Peri- and postpubertal boars accumulate substances (e.g., androstenone and skatole) in their fatty tissue that are responsible for boar taint in pork. The objective of this study was to assess the efficacy of a GnRH vaccine, Improvac, in eliminating boar taint. Three hundred male (200 intact boars, 100 barrows) crossbred (Large White x Landrace) pigs were used in a 2 x 3 factorially arranged experiment. The respective factors were sex group (barrows, boars treated with placebo, or boars treated with Improvac) and slaughter age (23 or 26 wk). Vaccines were administered 8 and 4 wk before slaughter. All Improvac-treated pigs exhibited anti-GnRH titers. Testes and bulbo-urethral gland weights in treated pigs were reduced by approximately 50% (P < 0.001) and serum testosterone levels were below 2 ng/mL in the majority of treated boars (94 and 92% across both age groups at 2 and 4 wk, respectively). Boar taint, as assessed by the concentration of androstenone and skatole in s.c. fat, was suppressed to low or undetectable levels in 100% of Improvac-treated boars. No Improvac-treated pigs had significant concentrations of either androstenone (> 1.0 microg/g) or skatole (> 0.20 microg/g). In contrast, 49.5% of placebo-treated controls had significant androstenone and 10.8% had significant skatole levels, resulting in 10% of the control boars with high concentrations of both compounds. The mean concentrations of taint compounds in the Improvac-treated pigs were not significantly different from those in barrows. Improvac-treated boars grew more rapidly (P = 0.051 and < 0.001 for pigs slaughtered at 23 and 26 wk of age, respectively) than control boars over the 4 wk after the secondary vaccination, possibly because of reduced sexual and aggressive activities. Compared with barrows, Improvac-treated boars were leaner and had superior feed conversion efficiency. The vaccine was well tolerated by the pigs, and no observable site reactions could be detected at the time of slaughter. Vaccination of boars with Improvac allows production of heavy boars with improved meat quality through prevention and control of boar taint.

Adipose Tissue↗
PubMed2001

Magnetic source imaging of late evoked field responses to vowels: toward an assessment of hemispheric dominance for language.

OBJECT: The goal of this study was to determine whether the late neuromagnetic field elicited by simple speech sounds, which is detected by magnetoencephalography, may be used to estimate hemispheric dominance for language and to guide or constrain the intraoperative search for essential language sites. If sufficiently robust, a noninvasive method for assessing hemispheric dominance for language could reduce the necessity for amobarbital testing and the extent of intraoperative cortical stimulation-based mapping, both of which carry the risk of morbidity. METHODS: Fifteen patients undergoing surgery for tumors during which intraoperative language mapping would be performed and two additional patients in whom intracarotid amobarbital testing confirmed right-hemisphere language dominance participated. Following a primary auditory response sources of late neuromagnetic fields elicited by vowel stimuli were modeled and coregistered using magnetic resonance images to form magnetic source (MS) images. A laterality index (LI) was calculated by summing the number of equivalent current dipolar sources in the late fields detected from each hemisphere. In 14 right-handed patients, 10 displayed left asymmetric LIs (0.37 +/- 0.16. mean +/- standard error of the mean in 14 patients). For both right-hemisphere dominant patients in whom an LI was obtainable, the LI was rightward. Stimulation-mapped essential language sites were found in 7 of 15 patients. For six of these seven patients, the MS image-derived LI was leftward. CONCLUSIONS: Asymmetry in single equivalent dipole modeling of the late neuromagnetic field evoked by simple speech sounds correlates with hemispheric language dominance, although not to the degree necessary for individual clinical predictions. With further development, MS imaging of simple language tasks may be used preoperatively to predict language dominance and even to identify or constrain the intraoperative search for likely sites of essential language cortex.

Acoustic Stimulation↗