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Biomedical subjects

D Buck

Publications and source records attributed to D Buck.

At least 37 records · Page 2Linked to original sources
PubMed2000

Percutaneous fibrin sheath stripping versus transcatheter urokinase infusion for malfunctioning well-positioned tunneled central venous dialysis catheters: a prospective, randomized trial.

PURPOSE: To compare central dialysis catheter patency rates after stripping procedures with those after urokinase (UK) infusion. MATERIALS AND METHODS: Fifty-seven tunneled catheters with either (i) flow rates less than 250 mL/min and established baseline flow rates > or = 300 mL/min or (ii) flow rates 50 mL/min less than higher established baseline flows were prospectively randomized to undergo stripping procedures (n = 28) or UK infusion (n = 29) at 30,000 U/h via each port concurrently, for a total 250,000 U. Success and patency were determined by dialysis at normal flow rates (> or = 300 mL/min) or at the previously established higher baseline rate. Flow rates were monitored weekly. Primary patency ended with catheter malfunction or removal. Kaplan-Meier survival analysis was used to construct survival curves. RESULTS: In the stripping group, initial clinical success was 89% (25 of 28). The 15-, 30-, and 45-day primary patency rates were 75% (n = 20), 52% (n = 13), and 35% (n = 8), respectively. The median duration of additional function was 32 days (95% CI: 18-48 d). In the UK group, initial clinical success was 97% (28 of 29). The 15-, 30-, and 45-day primary patency rates were 86% (n = 21), 63% (n = 13), and 48% (n = 9), respectively. The median duration of additional patency was 42 days (95% CI: 22-153 d). The Wilcoxon test for equality detected no significant difference in the survival curves for the two treatment groups (P = .236). CONCLUSION: There is no significant difference in time to primary patency between the two methods. Both allow temporary catheter salvage in most patients.

Adult↗
PubMed2000

Is there a role for immunoblots in the diagnosis of latex allergy? Intermethod comparison of in vitro and in vivo IgE assays in spina bifida patients.

BACKGROUND: The best diagnostic method for latex allergy is still controversial. This investigation was designed to evaluate the diagnostic efficiency of immunoblotting in comparison with established in vitro and in vivo test systems. METHODS: A total of 108 spina bifida patients were investigated by questionnaire and skin prick test (SPT). Specific serum IgE to latex was analyzed by the Pharmacia CAP FEIA immunoassay, DPC AlaSTAT microplate immunoassay, and DPC AlaBLOT immunoblot. Patients were regarded as latex allergic if they reacted positively to challenge by the latex glove wearing test. RESULTS: Thirty-four patients reacted positively to challenge. The sensitivity rates were 97% (SPT), 94% (immunoblot, CAP), 74% (AlaSTAT), and 35% (clinical history). The specificity rates were 92% (clinical history), 88% (AlaSTAT), 77% (SPT), 76% (CAP), and 69% (immunoblot). If two methods were combined, efficiency rates were highest for SPT combined with CAP (sensitivity 94%, specificity 82%), with AlaSTAT (sensitivity 74%, specificity 92%), or with immunoblot (sensitivity 91%, specificity 84%). The sera of challenge-positive patients recognized more immunoblot bands than challenge-negative patients, and the severity of symptoms correlated with the number of recognized bands. CONCLUSIONS The diagnostic efficiency of immunoblotting is not superior to that of SPT. However, immunoblotting may serve as an additional tool to increase slightly the specificity of SPT and specific serum IgE tests.

Adolescent↗
PubMed2000

Ventricular shunts and the prevalence of sensitization and clinically relevant allergy to latex in patients with spina bifida.

Patients with spina bifida represent the highest-risk group for developing hypersensitivity to latex. Recognized risk factors for these patients are repeated surgery and an atopic disposition. Our aim was to study the influence of a ventricular shunt as an independent risk factor. One hundred and sixty-one patients with spina bifida (median age 10 years) were investigated for the presence of a shunting device and the number, type and date of previous surgical interventions. Additionally, skin-prick tests and provocation tests were performed in order to classify sensitized and symptomatic latex-allergic individuals. Eighty-eight patients (54.7%) were sensitized; 55 (34.2%) were provocation-positive. Patients with a shunt system had undergone a significantly higher number of surgical procedures (p < 0.0001) and showed significantly higher levels of immunoglobulin E (IgE)-antibodies to latex (p < 0.0001) than patients without a shunting device. The total number of operations correlated significantly with the level of IgE-antibodies to latex in serum (p < 0.0001), whereas the number of shunt operations in patients with a ventricular shunt did not significantly correlate with the degree of sensitization. In conclusion, patients with spina bifida who have a ventricular shunt are at particularly high risk because they undergo a significantly higher number of operations than patients without a ventricular shunt. However, the ventricular shunt does not seem to be an independent risk factor. Furthermore, this study emphasizes that individuals at high risk, such as patients with spina bifida, should be handled latex-free from the very beginning of life.

Adolescent↗
PubMed2000

The efficiency of the community dental service in England: a data envelopment analysis.

OBJECTIVES: To assess the efficiency with which health authorities' Community Dental Services provide dental care in England. METHODS: A data envelopment analysis of inputs (hours worked by dental officers, therapists, hygienists and others) and outputs (screening, treatment, prevention) of the Community Dental Service (CDS) was conducted. Relative efficiency ratings of the CDS by health authority were further analysed in order to identify external factors which effect efficiency and are outside the control of the Community Dental Service. RESULTS: The relative efficiency of the CDS varies widely in England--on average the CDS is operating at 75% of efficient levels compared to best-practice services. This could not be explained by plausible factors outside the CDS's control, such as differences in deprivation and urban-rural differences between health authorities. CONCLUSIONS: These results, if validated by further studies, should be disturbing since many Community Dental Services services appear to be under-performing. However, this data-driven study could not uncover the detailed context of an individual service's performance. A useful next step would be detailed case-studies of several "star" and under-performing services to search for deeper reasons underpinning relative performance levels.

Benchmarking↗
PubMed2000

The stigma of epilepsy: a European perspective.

PURPOSE: To study the stigma of epilepsy in a European sample. METHODS: Clinical and demographic details and information about patient-perceived stigma was collected by using self-completed questionnaires mailed to members of epilepsy support groups. RESULTS: Stigma data were collected from >5,000 patients living in 15 countries in Europe. Fifty-one percent reported feeling stigmatised, with 18% reporting feeling highly stigmatised. High scores were correlated with worry, negative feelings about life, long-term health problems, injuries, and reported side effects of antiepileptic drugs (AEDs). Cross-cultural comparisons revealed significant differences between countries. A multivariate analysis identified impact of epilepsy, age of onset, country of origin, feelings about life, and injuries associated with epilepsy as significant contributors on scores on the stigma scale. CONCLUSIONS: This study confirms the findings of previous studies that have identified the importance of both clinical and nonclinical factors in understanding the stigma of epilepsy. The results of cross-cultural differences require further explanation, and much more research should be conducted to reduce the stigma associated with epilepsy.

Adolescent↗
PubMed2000

Evaluation of measures used to assess quality of life after stroke.

BACKGROUND AND PURPOSE: Assessment of quality of life (QOL) after stroke is becoming common with the recognition that evaluation of treatment should include quality as well as quantity of survival. This article will outline the main conceptual and methodological issues in QOL assessment, highlight advantages and disadvantages of measures used in stroke QOL research, and discuss some unresolved issues. SUMMARY OF REVIEW: We undertook a MEDLINE search using the keywords "stroke" and "quality of life" and reviewed 3 key texts on QOL measurement in stroke. Fifteen generic and 10 condition-specific measures used to assess QOL in stroke were identified and evaluated with the following criteria: reliability, validity, responsiveness, precision, acceptability, suitability for proxy respondents, mode of administration, and use of patient-centered approaches in development. Domains covered and level of comprehensiveness varied widely between generic and stroke-specific measures. No stroke-specific instruments used patient-centered approaches in their development. Four stroke-specific measures (Frenchay Activities Index, Niemi QOL scale, Ferrans and Powers QOL Index-Stroke Version, and Stroke-Adapted Sickness Impact Profile [SA-SIP30]) provided evidence of reliability and validity. CONCLUSIONS: The need remains for a patient-centered, psychometrically robust, stroke-specific QOL measure. Patients should be involved in each stage of instrument development. Caution is needed in the selection of an instrument to measure QOL after stroke. Although the Ferrans and Powers QOL Index-Stroke Version, Niemi QOL scale, SA-SIP30, and Sickness Impact Profile come closest to satisfying many of the criteria outlined in this article, the selection of any individual instrument depends on the specific goals and constraints of a particular study.

Evaluation Studies as Topic↗
PubMed2000

Economic evaluation and dentistry.

This article is a brief guide to economic evaluation and dentistry. It outlines the most common methods such as cost-effectiveness analysis and cost-benefit analysis; discusses how and when they should be used; gives some dental examples; and outlines important issues that need to be borne in mind when interpreting them. It also corrects one or two common misunderstandings about economic evaluation.

Costs and Cost Analysis↗
PubMed1999

The DNA sequence of human chromosome 22.

Knowledge of the complete genomic DNA sequence of an organism allows a systematic approach to defining its genetic components. The genomic sequence provides access to the complete structures of all genes, including those without known function, their control elements, and, by inference, the proteins they encode, as well as all other biologically important sequences. Furthermore, the sequence is a rich and permanent source of information for the design of further biological studies of the organism and for the study of evolution through cross-species sequence comparison. The power of this approach has been amply demonstrated by the determination of the sequences of a number of microbial and model organisms. The next step is to obtain the complete sequence of the entire human genome. Here we report the sequence of the euchromatic part of human chromosome 22. The sequence obtained consists of 12 contiguous segments spanning 33.4 megabases, contains at least 545 genes and 134 pseudogenes, and provides the first view of the complex chromosomal landscapes that will be found in the rest of the genome.

Animals↗
PubMed1999

Impact of nicotine on bone healing.

A limited number of experimental animal studies and in vitro data confirm that nicotine impairs bone healing, diminishes osteoblast function, causes autogenous bone graft morbidity, and decreases graft biomechanical properties. Therefore, our long-term goal is to develop an effective therapy to reverse the adverse impact of nicotine from tobacco products. However, before accomplishing this goal, we had to develop an animal model. Our hypotheses were nicotine administration preceding and following autogenous bone grafting adversely affected autograft incorporation and depressed donor site healing in a characterized animal wound model. Hypothesis testing was accomplished in bilateral, 4-mm diameter parietal bone defects prepared in 60 Long-Evans rats (male, 35-day-old). A 4-mm diameter disk of donor bone was removed from the left parietal bone and placed in the contralateral defect. The donor site served as a spontaneously healing bone wound. The rats were partitioned equally among three doses of nicotine administered orally in the drinking water (12.5, 25, and 50 mg/L). For each dose, the duration and sequence of nicotine treatment followed four courses, including no nicotine and designated combinations of nicotine administration and abatement prior to and following osseous surgery. Experimental sites were recovered on 14 and 28 days postsurgery, responses quantitated, and data analyzed by analysis of variance and post hoc statistics (p < or = 0.05). We developed a convenient and effective osseous model, and the results validated our hypothesis that nicotine negatively impacts on bone healing.

Animals↗
PubMed1999

Tissue-engineered bone biomimetic to regenerate calvarial critical-sized defects in athymic rats.

A tissue-engineered bone biomimetic device was developed to regenerate calvaria critical-sized defects (CSDs) in athymic rats. Well-documented evidence clearly confirms that left untreated, CSDs will not spontaneously regenerate bone. To accomplish regeneration, four candidate treatments were assessed: porous poly(D,L-lactide) and type I collagen (PLC), PLC and human osteoblast precursor cells (OPCs) at 2 x 10(5) (PLC/OPCs), PLC and 50 microg of recombinant human bone morphogenetic protein-2 (PLC/rhBMP-2), and PLC/OPCs/rhBMP-2 (the bone biomimetic device). The hypotheses for this study were PLC/OPCs/rhBMP-2 would promote more new bone formation in CSDs than the other treatments and the amount of bone formation would be time dependent. To test the hypotheses, outcomes from treatments were measured at 2 and 4 weeks postoperatively by radiomorphometry for percent radiopacity and by histomorphometry for square millimeters of new bone formation. Data were analyzed by analysis of variance and Fisher's protected least significant difference for multiple comparisons with p < or = 0.05. At 2 and 4 weeks, radiomorphometric data revealed PLC/rhBMP-2 and PLC/OPCs/rhBMP-2 promoted significantly more radiopacity than either PLC or PLC/OPCs. Histomorphometry data at 2 and 4 weeks indicated significantly more new bone formation for PLC/rhBMP-2, PLC/OPCs/rhBMP-2, and PLC/OPCs compared to PLC. By 4 weeks, PLC/OPCs/rhBMP-2 and PLC/rhBMP-2 had regenerated the CSDs with more new bone than the other treatments; the quantity of bone at 4 weeks for these treatments was greater than at 2 weeks.

Animals↗
PubMed1999

Cloning, expression, and characterization of recombinant Hev b 3, a Hevea brasiliensis protein associated with latex allergy in patients with spina bifida.

BACKGROUND: Two natural rubber latex proteins, Hev b 1 and Hev b 3, have been described in spina bifida (SB)-associated latex allergy. OBJECTIVE: The aim of this study was to clone and express Hev b 3 and to obtain the immunologic active and soluble recombinant allergen for diagnosis of SB-associated latex allergy. METHODS: A complementary DNA (cDNA) coding for Hev b 3 was amplified from RNA of fresh latex collected from Malaysian rubber trees (Hevea brasiliensis). PCR primers were designed according to sequences of internal peptide fragments of natural (n) Hev b 3. The 5'-end sequence was obtained by specific amplification of cDNA ends. The recombinant (r) Hev b 3 was produced in Escherichia coli as a 6xHis tagged protein. Immunoblotting and inhibition assays were performed to characterize the recombinant allergen. RESULTS: An Hev b 3 cDNA clone of 922 bp encoding a protein of 204 amino acid residues corresponding to a molecular weight of 22.3 kd was obtained. In immunoblots 29/35, latex-allergic patients with SB revealed IgE binding to rHev b 3, as did 4 of 15 of the latex-sensitized group. The presence of all IgE epitopes on rHev b 3 was shown by its ability to abolish all IgE binding to nHev b 3. Hev b 3 is related to Hev b 1 by a sequence identity of 47%. Cross-reactivity between these 2 latex allergens was illustrated by the large extent of inhibition of IgE binding to nHev b 1 by rHev b 3. CONCLUSION: rHev b 3 constitutes a suitable in vitro reagent for the diagnosis of latex allergy in patients with SB. The determination of the full sequence of Hev b 3 and the production of the recombinant allergen will allow the epitope mapping and improve diagnostic reagents for latex allergy.

Adolescent↗
PubMed1999

Costs of formal care for frail older people in England: the resource implications study of the MRC cognitive function and ageing study (RIS MRC CFAS).

The aim of this paper is to quantify service use and costs of supporting frail older people at home in the community, using data collected in a longitudinal multicentre stratified randomised study for 1055 mentally frail, physically frail, and mentally and physically frail subjects. Average costs per person per week were found to total 64.45 Pounds Sterling, with a small number of services accounting for a large proportion of the total costs. The level of services offered by the nonstatutory voluntary and private sectors was found to be small. To highlight issues for policy makers, the extent of cost variations between a number of different subgroups were calculated. These bivariate analyses revealed substantial variation in costs, especially according to household structure, type of frailty, whether admission to continuing care accommodation occurred and survival. Multiple regression analysis demonstrated that 26% of the variation in log average weekly costs could be explained by a number of socio-demographic and health status variables. A particularly close relationship was observed between costs and whether admission to continuing care accommodation occurred, highlighting a need for policy-makers to examine the nature and scale of provision of alternative community based care packages. The results demonstrate that descriptive cost data such as those presented can provide information useful to the planning process, enabling more informed choices to be made over the provision of services for particular groups of people.

Aged↗
PubMed1999

Can we measure the social importance of health care?

This paper examines the extent to which it is possible to measure the social importance, or macro benefits, of health care. In contrast to the many micro studies of the benefits of specific health care interventions, methodology relating to such macro benefits is at a very rudimentary stage. A theoretical model is presented that seeks to capture the social consequences of a health care system. In light of this model, three existing empirical approaches to answering the question are examined: the inventory approach, the avoidable mortality approach, and the production function approach. All three have severe limitations in terms of the underlying theoretical model, data availability, and analytic tools employed. A more fruitful approach may be to investigate the value of undertaking a direct survey of citizens' attitudes toward their health care system.

Delivery of Health Care↗
PubMed1999

The SF-36 as a health status measure for epilepsy: a psychometric assessment.

A considerable literature is now available on the applications and psychometric properties of the MOS SF-36 Health Survey. In epilepsy, the SF-36 has been used as a health status measure in its own right and as the stem for two condition-specific measures. This paper replicates for epilepsy previous work to support use of the SF-36 across a range of clinical conditions. Data were obtained from a European-wide descriptive study of quality of life of adults with epilepsy; analysis of responses on the SF-36 is based on 4,929 subjects in eight countries. Missing value rates for all SF-36 items were low; percentages for whom complete information available for subscales ranged from 95.7% to 98.6%. All subscales passed tests for item-internal consistency and item-discriminant validity. Reliability coefficients exceeded the standard recommended for group comparisons across all subscales. Floor effects were negligible for all but the two role disability subscales; there were substantial ceiling effects for five of the SF-36 subscales. We conclude that the SF-36 is a valid and reliable health status measure for descriptive studies of people with epilepsy, but ceiling effects may limit its usefulness as an outcome measure in the assessment of new treatments.

Adolescent↗
PubMed1999

Cross-cultural differences in health-related quality of life of people with epilepsy: findings from a European study.

PURPOSE: To examine between-country differences in health-related quality of life (HRQOL) of adults with epilepsy across a large number of European countries. METHODS: Self-completion postal questionnaire sent to large sample of adults with epilepsy, recruited from epilepsy support groups or epilepsy outpatient clinics. The questionnaire was developed in English and translated. Back-translations from each language were checked for accuracy. The questionnaire sought information on clinical and socio-demographic details, and contained a number of previously validated scales of psychosocial well-being (the SF-36, the perceived impact of epilepsy scale, and a feelings of stigma scale). RESULTS: Controlling for socio-demographic and clinical characteristics, significant between-country differences were found in scores on the perceived impact of epilepsy scale, on seven of the eight SF-36 domains, and on the feelings of stigma scale. Respondents in Spain and the Netherlands fared consistently better, whilst those in France fared poorest, compared to those in other countries in terms of the various HRQOL measures used. CONCLUSION: Several possible reasons for the cross-cultural differences in HRQOL are proposed. Clearly, there is no single explanation and there may also be reasons which we have overlooked. This study emphasises the need for further comprehensive research in order that the position of people with epilepsy in different countries be more thoroughly understood in the social context.

Adolescent↗
PubMed1999

Changing the number of submaximal exercise bouts effects calculation of MAOD.

The aim of this present study was to evaluate the effect of the number of submaximal exercise bouts used to construct the power-VO2 regression, on calculations of MAOD through the sequential and systematic removal of the highest and lowest submaximal VO2 values from the standard ten point regression line. Eight trained male cyclists participated in this study. The mean (+/- SD) age, height, weight and VO2max for the subjects were 25+/-7 yr, 178.2+/-3.0 cm, 69.9+/-4.9 kg and 57.5+/-6.9 ml x kg(-1) x min(-1). After VO2max testing each subject undertook ten submaximal exercise bouts at between 30% and 90% VO2max and one supramaximal bout calculated to elicit 100% VO2max. Expired gases were measured via open circuit spirometry. The mean power output of the supramaximal bout was 336.5+/-442.5 W and the mean duration was 269.4+/-42.9 s. The correlation coefficients ranged from 0.981 to 0.996 while the MAOD values ranged from 29.6+/-15.7 ml O2 eq x kg(-1) to 61.3+/-44.7 ml O2 eq x kg(-1). When compared to the standard ten points, as a percentage difference, this difference ranged from 4.1+/-3.6% to 83.7+/-54.9%. The main finding of this study is that inaccuracies occur in the measurement of MAOD when less than ten points are used in the calculation. Further study is required for the development of a standardised protocol for the accurate, valid and reliable measurement of MAOD.

Adult↗