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Biomedical subjects

J Henderson

Publications and source records attributed to J Henderson.

At least 109 records · Page 6Linked to original sources
PubMed1996

Qualitative evaluation of the Canadian Medical Association's counselling guidelines for HIV serologic testing.

OBJECTIVE: To evaluate the face and content validity of the CMA's counselling guidelines for HIV serologic testing in order to prepare a revised edition. DESIGN: Qualitative evaluation by structured focus groups in September and October 1994 to assess the relevance, clarity and practicality of the guidelines, followed by content analysis of the discussions. SETTING: Vancouver, Winnipeg, Toronto, Montreal, Quebec City and St. John's. PARTICIPANTS: Primary care physicians randomly selected from the CMA database and nonrandomly selected from the Canadian Medical Directory who had limited experience with HIV testing and counselling and who provided an appropriate mix of characteristics in terms of practice type (solo and group), setting (urban and rural), age and sex. A total of 1247 physicians were approached for the study; a convenience sample of 68 were recruited, of whom 56 participated. The average size of each focus group was eight physicians. OUTCOME MEASURES: Clinical experience and information sources with respect to HIV testing, reactions to the counselling guidelines, and suggestions for revisions and improvements to the guidelines. RESULTS: Most (96% [54/56] of the participants had ordered HIV serologic testing for patients in the 6 months preceding the focus groups, and about half of them (52% [28/54]) had at least one patient with a positive test result. Many (59% [33/56]) of the participants had a copy of the guidelines at the time of recruitment; 19 (58%) of them had used the guidelines in the months before the focus groups. The parts of the guidelines most often read were the checklists and inset boxes. Recommendations for revisions in content were for more information on legal and ethical issues, information on new issues (e.g., rapid testing) and guidelines on how best to tell a patient about a positive test result; recommendations for revisions in format included more tables, algorithms, bulleted points and white space, less text, larger type and plainer language. CONCLUSIONS: The focus groups provided detailed, credible and consistent information about the face and content validity of the HIV counselling guidelines. They are a useful qualitative method for evaluating the relevance, clarity and practicality of clinical practice guidelines at the inception or revision stage.

AIDS Serodiagnosis↗
PubMed1996

Protein retention in the endoplasmic reticulum of insect cells is not compromised by baculovirus infection.

High level expression of the major auxin-binding protein (ABP1) from maize (Zea mays L.) has been used to demonstrate that the machinery for retaining proteins in the endoplasmic reticulum (ER) of insect cells functions efficiently throughout the baculovirus infection cycle. Immunolocalization showed wild-type ABP1 (ABP1-KDEL) to be targeted to the lumen of the ER, in accordance with its signal peptide and carboxyterminal KDEL ER-retention signal. The protein accumulated in dilations of the ER, and none was detected at the cell surface. Immunoblotting of concentrated culture medium confirmed that ABP1-KDEL was not secreted at a detectable level. In contrast, when the carboxyterminus was mutated to KEQL, secretion of the baculovirus-expressed protein was readily detected. Immunolocalization and immunoblotting demonstrated that a high proportion of the ABP1-KEQL protein was secreted at the cell surface and into the culture medium. The data demonstrate that the ER of insect cells has a great capacity to retain proteins and that this property is largely unaffected by the cellular disruption caused by baculovirus replication.

Amino Acid Sequence↗
PubMed1996

Mobilizing positive reinforcement in communities to reduce youth access to tobacco.

A community intervention to mobilize positive reinforcement for not selling tobacco to young people was evaluated. The intervention had five components: (a) mobilization of community support, (b) merchant education, (c) changing consequences to clerks for selling or not selling to those under 18, (d) publicity about clerks' refusals to sell, and (e) feedback to store owners or managers about the extent of their sales to adolescents. A multiple baseline design experiment was conducted, in which two small Oregon communities received the intervention, while two other continued in baseline. Outlets' willingness to sell was assessed repeatedly by teenage volunteers. The intervention significantly reduced the proportion of stores willing to sell. Mobilizing social and material reinforcement for stores not selling tobacco to young people is a viable means of reducing such sales. It may be especially valuable in communities where laws against sales to minors go unenforced.

Adolescent↗
PubMed1996

Hyperglycemia results in an increase in myocardial interstitial glucose and glucose uptake during ischemia.

The purpose of this investigation was to assess the effects of hyperglycemia, in the absence of changes in plasma insulin and arterial free fatty acid (FFA) levels, on interstitial glucose levels and glucose uptake across the left ventricular wall during ischemia in domestic swine. Insulin secretion was suppressed with a continuous infusion of somatostatin. Arterial FFA levels remained stable due to the suppression of insulin. Microdialysis probes were used to estimate changes in interstitial glucose and lactate, and were placed in the subepicardium and the subendocardium of the left anterior descending ([LAD] ischemic) coronary artery perfusion bed and in the midmyocardium of the circumflex ([CFX] nonischemic) perfusion bed. The LAD coronary artery was cannulated and perfused with blood from the femoral artery through an extracorporal perfusion circuit. Ischemia was induced in the LAD perfusion bed by reducing the flow of the LAD perfusion pump by 60% for 50 minutes, and was followed by 30 minutes of reperfusion. Twenty minutes into the ischemic period, seven animals were given a bolus injection of 50% glucose (200 mg/kg) followed by a glucose infusion (10 mg/kg/min), resulting in an increase in arterial glucose levels from 5 to 13 mmol/L in the hyperglycemic group. Hyperglycemia resulted in a marked increase in dialysate glucose during ischemia and a greater than twofold increase in glucose extraction and uptake. Dialysate glucose correlated with plasma glucose in all three perfusion beds. In conclusion, hyperglycemia, in the absence of an increase in insulin and a decrease in arterial FFA, resulted in a doubling of glucose extraction, delivery, and uptake, which corresponded to the twofold elevation in interstitial glucose during ischemia.

Animals↗
PubMed1996

Enhanced LTP in mice deficient in the AMPA receptor GluR2.

AMPA receptors (AMPARs) are not thought to be involved in the induction of long-term potentiation (LTP), but may be involved in its expression via second messenger pathways. However, one subunit of the AMPARs, GluR2, is also known to control Ca2+ influx. To test whether GluR2 plays any role in the induction of LTP, we generated mice that lacked this subunit. In GluR2 mutants, LTP in the CA1 region of hippocampal slices was markedly enhanced (2-fold) and nonsaturating, whereas neuronal excitability and paired-pulse facilitation were normal. The 9-fold increase in Ca2+ permeability, in response to kainate application, suggests one possible mechanism for enhanced LTP. Mutant mice exhibited increased mortality, and those surviving showed reduced exploration and impaired motor coordination. These results suggest an important role for GluR2 in regulating synaptic plasticity and behavior.

Animals↗
PubMed1996

Maintenance following a very-low-calorie diet.

The authors posed 2 questions in this randomized study of maintenance procedures in which participants were followed for 15 months after completion of a very-low-calorie diet: Would stimulus narrowing during the reintroduction of solid food, achieved by the use of prepackaged foods, improve weight losses and the maintenance of those losses as compared with the use of regular food? Would reintroduction of foods dependent on progress in losing or maintaining weight be superior to reintroduction on a time-dependent basis? Neither the stimulus narrowing condition nor the reintroduction procedure enhanced either maximum weight loss or maintenance of those losses. The stimulus narrowing condition appeared to be poorly tolerated; compliance and attendance were poorer in this condition than in the regular food condition.

Adult↗
PubMed1996

Comparison of lower limb arterial assessments using color-duplex ultrasound and ankle/brachial pressure index measurements.

The strength of agreement between two noninvasive methods of assessing lower limb arterial disease and their relationship to patient symptoms following exercise have been investigated. Color-duplex ultrasound (CDU) and ankle/brachial pressure index (ABPI) (before and afer exercise) measurements were obtained from 200 consecutive patients referred to a vascular investigations laboratory. From these patients, 290 limbs were available for study, comprising limbs without previous vascular surgery, from patients without diabetes and who could attempt a walking exercise test. The overall level of agreement between CDU and resting ABPI measurements was 83% (Kappa 0.66). The ABPI technique identified the more serious disease; a resting ABPI of less than 0.6 gave 100% agreement with CDU. With higher resting ABPIs the level of agreement became poorer: 83% (0.6 < or = ABPI <0.9) and 76% (normal ABPI > or = 0.9). The addition of postexercise ABPI measurements in determining significant arterial disease increased the strength of relationship between the two techniques by only 2% (85%, Kappa 0.69). The exercise test was generally limited by the most symptomatic limb in each patient, and the agreement between CDU and postexercise ABPI measurements in these limbs was higher at 93% (Kappa 0.81). In comparison, agreement for the least symptomatic group of limbs was found to be poor (69%, Kappa 0.37). Compared with symptoms after exercise, overall agreements with CDU and ABPI were both 67% (Kappa 0.27). The agreement was better (91%) when the resting ABPI was less than 0.6. The ABPI is biased toward the detection of more severe disease and is more consistent with CDU when the most symptomatic limbs are compared. The relationship between either test and symptoms after exercise is strong only for limbs with major disease.

Adult↗
PubMed1996

Finding genes in DNA using decision trees and dynamic programming.

This study demonstrates the use of decision tree classifiers as the basis for a general gene-finding system. The system uses a dynamic programming algorithm that finds the optimal segmentation of a DNA sequence into coding and non-coding regions (exons and introns). The optimality property is dependent on a separate scoring function that takes a subsequence and assigns to it a score reflecting the probability that the sequence is an exon. In this study, the scoring functions were sets of decision trees and rules that were combined to give the probability estimate. Experimental results on a newly collected database of human DNA sequences are encouraging, and some new observations about the structure of classifiers for the gene-finding problem have emerged from this study. We also provide descriptions of a new probability chain model that produces very accurate filters to find donor and acceptor sites.

Algorithms↗
PubMed1995

Waiting list dynamics and the impact of earmarked funding.

OBJECTIVE: To determine how changes in the number of admissions from waiting lists and changes in the number of additions to the lists are related to list size and waiting times, in the context of local waiting list initiatives. DESIGN: Review of national and Körner statistics. SETTING: England (1987-94) and districts of the former Oxford region (1987-91). MAIN OUTCOME MEASURES: Correlation of quarterly changes in the number of admissions from waiting lists in England with changes in total list size, numbers of patients waiting one to two, or over two years, and number of additions to the lists; examination of changes in waiting list statistics for individual district specialties in one region in relation to funding for waiting list initiatives. RESULTS: Nationally, changes in the number of admissions to hospital from lists closely correlated with changes in the number of additions to lists (r = 0.84; P < 0.01). After adjusting for changes in the number of additions to lists, changes in the number of admissions correlated inversely with changes in list size (r = -0.62; P < 0.001). Decreases in the number of patients waiting from one to two years were significantly associated with increases in the number of admissions (r = -0.52; P < 0.01); locally, only six of 44 waiting list initiatives were followed by an increase in admissions and a fall in list size, although a further 11 were followed by a fall in list size without a corresponding increase in admissions. CONCLUSIONS: An increase in admissions improved waiting times but did not reduce list size because additions to the list tended to increase at the same time. The appropriateness of waiting list initiatives as a method of funding elective surgery should be reviewed.

England↗
PubMed1995

Stable expression of maize auxin-binding protein in insect cell lines.

To achieve continuous expression of the major maize auxin-binding protein (ABP1) in insect cells, the ABP1 gene coding region was placed under control of a baculovirus immediate-early gene promoter and transfected into Spodoptera frugiperda Sf9 cells. The ABP1 gene was detected in twelve cell lines, one of which was selected for detailed analysis. Immunolocalisation demonstrated that ABP1 was targeted to and retained in the endoplasmic reticulum (ER), in accordance with its signal peptide and carboxy-terminal KDEL ER-retention signal. We discuss the advantages of stable-transformation over transient expression systems for characterising proteins targeted to the secretory system of insect cells.

Animals↗
PubMed1995

Core and comprehensive health care services: 1. Introduction to the Canadian Medical Association's decision-making framework.

The CMA's decision-making framework on core (i.e., publicly funded) and comprehensive health care services emphasizes flexibility and recognizes three levels at which decisions can be made: between patients and physicians (micro), in the community or by society (meso) and by governments (macro). Three major content dimensions are considered quality of care (e.g., effectiveness, appropriateness and efficiency of health care services), ethics (e.g., decisions that reflect fairness and acceptability to patients and physicians) and economics (e.g., measurement of service costs against economic benefits in a time of severe economic restraint). There are challenges in applying the framework; however, by providing decision-makers with the knowledge and tools needed to assist in the process, it is hoped that the first and foremost concern will continue to be the quality of patient care so highly valued by Canadians.

Canada↗
PubMed1995

A survey of the acoustic outputs of diagnostic ultrasound equipment in current clinical use.

Surveys published up to 1991 have highlighted a steady increase in the acoustic outputs from diagnostic ultrasound equipment. Since 1991 we have made measurements of the maximum peak negative pressure (p-) and spatial peak temporal average intensity (ISPTA) produced by 223 probes from 82 scanning systems in current clinical use in the Northern Region in the UK. Measurements have also been made of the maximum total acoustic power generated by 45 probes from 17 scanners. The results from these measurements are presented in this article and compared to the results of a similar survey of equipment from both the Northern and Wessex Regions in the UK and published in 1991. The comparison shows that measured ISPTA values have increased approximately sixfold in B mode and approximately threefold in colour Doppler mode. Also, measured total acoustic power values have doubled in pulsed Doppler mode. The present survey also draws attention to some particularly high ISPTA values obtained from a number of probes and scanning systems. This survey has shown that measurements of acoustic outputs from diagnostic ultrasound scanners in current clinical use are substantially higher than reported in earlier surveys and, for certain scanners, the acoustic outputs from scanned beam modes of operation can reach levels hitherto only found in pulsed Doppler mode.

Acoustics↗
PubMed1995

Does interpersonal therapy help patients with binge eating disorder who fail to respond to cognitive-behavioral therapy?

The aim of this quasi-experimental study was to examine the effectiveness of group interpersonal therapy (IPT) in treating overweight patients with binge eating disorder who did not stop binge eating after 12 weeks of group cognitive-behavioral therapy (CBT). Participants in this study were randomly allocated to either group CBT or to an assessment-only control group. After 12 weeks of treatment with CBT, 55% of participants met criteria for improvement and began 12 weeks of weight loss therapy, whereas the nonresponders began 12 weeks of group IPT. Over the 24-week period, participants who received treatment reduced binge eating and weight significantly more than the waiting-list control group. However, IPT led to no further improvement for those who did not improve with CBT. Predictors of poor outcome were early onset of, and more severe, binge eating.

Adult↗
PubMed1995

Performance on the athletic training certification examination based on candidates' routes to eligibility.

The National Athletic Trainers' Association Board of Certification initiated a task force whose purpose is to evaluate the criteria that determine eligibility for the athletic training certification examination. Candidates may qualify to take the examination through one of two routes: an academic-based curriculum program or the practical education, work-experience-based internship route. The certification examination is comprised of three sections: a written examination, a written simulation, and a practical examination. We retrospectively examined certification examination scores during a 2-year period to determine whether a significant difference existed between the two groups of candidates. Test results for first-time candidates sitting for one of the nine examinations administered during 1992 and 1993 were extracted from the data base maintained by Columbia Assessment Services, Inc (Raleigh, NC) and grouped according to the candidates' route to eligibility. Curriculum candidates had significantly greater scores than did internship candidates on each of the three parts of the examination. Although the test analysis yields strong statistical power in interpreting these results, examination outcomes may also be influenced by the structure and content of the academic program followed, the quality of the clinical experience, the heterogeneity of each of the routes, and the psychosocial rigors of the examination process.

Journal Article↗
PubMed1995

Analysis of immunological alterations associated with testicular prostheses.

PURPOSE: Recipients of silicone gel filled testicular prostheses were evaluated for the possible immunological abnormalities of human adjuvant disease. MATERIALS AND METHODS: Medical record audits were performed for 48 recipients of a silicone gel filled testicular prosthesis. Seven patients consented to a detailed health profile questionnaire, physical examination and serological testing. RESULTS: Retrospective chart analyses and physical examinations were unremarkable. Serological results and questionnaire responses varied. One patient with signs and symptoms suggestive of human adjuvant disease underwent prosthesis removal but adjacent tissues had no evidence of silicosis. Long-term followup was poor. CONCLUSIONS: Immunological alterations were present in 71.4% of examined recipients but they may have been coincidental. Careful followup of recipients of a silicone gel filled testicular prosthesis is needed.

Adolescent↗
PubMed1994

Fragile X induction systems in CVS cultures: effect on cytogenetic, PCR, and genomic Southern Blot DNA analyses of the FMR-1 gene.

Low fragile X frequencies have been commonly observed in chorionic villus sample (CVS) cultures, compared to subsequent analysis in whole blood or products of conception (POC). To investigate possible mechanisms for this effect, CVS cultures from a previously identified fragile X positive male, were restudied and compared to subsequent POC cultures from lung, muscle, skin, and thymus. Cultures were exposed, for the last 24 hours before harvesting, to FUdR, excess thymidine, and a combination of both. For CVS, only those cultures that were exposed to a combination of FUdR and excess thymidine showed positive cytogenetic findings (1/90 or 1.1%), agreeing with our original positive cytogenetic results (2/86 or 2.3%) for cultures exposed to excess thymidine. Fragile X frequencies in the POC tissues from this fetus increased to an average of 14%. PCR analyses showed full mutations (> 200 CGG repeats) in uninduced CVS cultures but induced cultures exhibited apparently smaller sizes in the range of 120-180 repeats. The results showed variability. In one instance, the banding pattern from one of the uninduced cultures was similar to the results where cultures were exposed to a double induction system. When PCR analyses were conducted on induced POC cultures, full mutations were observed in virtually all samples. Southern blot genomic analysis using probe StB12.3 showed an unmethylated full mutation in CVS cultures. Southern blot patterns from cultures of muscle revealed size variations of DNA bands in the premutation range representing unmethylated DNA as well as methylated full mutations. Finally, variations were also observed in lung and skin cultures, compared to CVS and muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Southern↗