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At least 1,369 records · Page 76Linked to original sources
PubMed2005

Patterns of graft and patient survival following renal transplantation and evaluation of serum creatinine as a predictor of survival: a review of data collected from one clinical centre over 34 years.

BACKGROUND: The pattern of renal transplantation has never been described since the introduction of the technique. The purpose of this study was therefore to characterise the pattern of renal transplantation from 1967 to 2000, focusing on renal graft function as a predictor of survival. METHODS: This study was a retrospective analysis of an electronic database. The setting was a single renal transplant centre in the United Kingdom covering a population of 2.2 million and included patients who received at least one renal transplant over the study period (n = 1516). The main outcome measures were patient and graft survival, acute rejection episodes and patterns of graft function, as measure by creatinine levels. RESULTS: There were 559 (36.8%) female patients; 109 (7.2%) patients had pre-existing diabetes. Patient survival was adversely affected by increased age at transplant (p < 0.001): 5-year patient survival from first transplant was 82% for patients aged 0 to 17 years, 80% for 18 to 49 years and 61% for > 49 years. Pre-existing diabetes also adversely affected survival (p < 0.01): 5-year graft survival was 63% for patients with diabetes versus 74% for those without. Graft survival was significantly associated with serum creatinine levels recorded 1 year post-primary transplant (p < 0.001) and with three or more acute rejection episodes (p < 0.05). Neither gender nor diabetes status were statistically significant in predicting graft survival. The number of acute rejection episodes was significantly greater in patients with pre-existing diabetes than those without (61% versus 42%, respectively; p < 0.001). There were no differences in the number of acute rejection episodes occurring across age groups. CONCLUSION: Patient and graft survival improved markedly over the 34-year study period, although patient survival has changed little since 1990. Serum creatinine levels are a reliable predictor of graft survival.

Adolescent↗
PubMed2003

Quality control and peak finding for proteomics data collected from nipple aspirate fluid by surface-enhanced laser desorption and ionization.

BACKGROUND: Recently, researchers have been using mass spectroscopy to study cancer. For use of proteomics spectra in a clinical setting, stringent quality-control procedures will be needed. METHODS: We pooled samples of nipple aspirate fluid from healthy breasts and breasts with cancer to prepare a control sample. Aliquots of the control sample were used on two spots on each of three IMAC ProteinChip arrays (Ciphergen Biosystems, Inc.) on 4 successive days to generate 24 SELDI spectra. In 36 subsequent experiments, the control sample was applied to two spots of each ProteinChip array, and the resulting spectra were analyzed to determine how closely they agreed with the original 24 spectra. RESULTS: We describe novel algorithms that (a) locate peaks in unprocessed proteomics spectra and (b) iteratively combine peak detection with baseline correction. These algorithms detected approximately 200 peaks per spectrum, 68 of which are detected in all 24 original spectra. The peaks were highly correlated across samples. Moreover, we could explain 80% of the variance, using only six principal components. Using a criterion that rejects a chip if the Mahalanobis distance from both control spectra to the center of the six-dimensional principal component space exceeds the 95% confidence limit threshold, we rejected 5 of the 36 chips. CONCLUSIONS: Mahalanobis distance in principal component space provides a method for assessing the reproducibility of proteomics spectra that is robust, effective, easily computed, and statistically sound.

Algorithms↗
PubMed2000

Change in bone mass after Colles' fracture: a case report on unique data collection and long-term implications.

The cast immobilization of a fractured limb results in a loss of bone mass; however, the long-term implications of that effect with regard to bone mineral status, particularly in other skeletal sites, are less known. The purpose of this study was to describe changes in bone mass in different skeletal sites triggered by Colles' fracture. The case is unique regarding the existence of baseline measurements taken just a few days before the fracture on all measurable skeletal sites, including the fractured radius. Therefore, it was also possible to determine whether the injury caused long-term bone loss in the affected and unaffected skeletal sites. The patient was a healthy, premenopausal Caucasian woman, in her late forties, who fractured her nondominant wrist as a result of low-impact fall on ice. The arm and the metacarpals were immobilized to the elbow for 5 wk. Bone mass measurements were performed with DPX-MD densitometer (Lunar Corp. Madison, WI) at baseline and 5, 10, 13, 21, and 52 wk postinjury. At the 5-wk measurement (on plaster removal) there was a notable increase in bone mineral density (BMD) and bone mineral content (BMC) in all sites of ulna and radius of the injured forearm (from 10 to 73%), followed by the apparent decline to or below the baseline at 10, 13, 21 and 52 wk of follow-up. Other skeletal sites were measured at 10 wk when a substantial decrease in BMD and BMC in some of the hip regions and lumbar spine was noticed; most notably in L3-L4, Ward's triangle, and femoral neck (from 2 to 8%) and remained such after 1 yr. Although this patient had a normal bone mineral status and no osteopenia detected before fracture, the trauma of radial fracture caused long-standing bone loss in fracture-prone areas-hip and spine. Because about 70% of bone strength is explained by its mineral density, the patient might be at increased risk for fracture later in life. The changes in bone mass after injury should be monitored and interpreted carefully, and more elaborate treatment of patients presenting with wrist fractures are needed to prevent any potential risk for later osteoporotic fractures in spine and hip and possible refracture of the injured extremity.

Absorptiometry, Photon↗
PubMed1975

Shaping data collection congruent with experimental hypotheses.

The influence of instructions and feedback from an experimenter on observational recordings of disruptive behavior was evaluated. Four subject-observers recorded four categories of disruptive behavior from videotapes of children in a classroom setting. Two sets of videotapes, labelled "baseline" and "treatment", were matched for rates of disruptive behavior in each category. The observers were told that two target behaviors were expected to decrease and the other two control behaviors were not expected to change during the treatment condition. During observational recording of treatment videotapes, the observers were given positive feedback when they reported decreases in the two target behaviors, and negative feedback when they reported either to change or increases in the two control behaviors. The target behaviors were recorded less frequently by observers, while recordings of control behaviors were unaffected during the treatment phase. These results suggest that contingent feedback to observers should be avoided as a possible source of bias in behavioral recordings.

Journal Article↗
PubMed2000

The role of population pharmacokinetics in drug development in light of the Food and Drug Administration's 'Guidance for Industry: population pharmacokinetics'.

Population pharmacokinetics (PPK) has evolved from a discipline primarily applied to therapeutic drug monitoring to one that plays a significant role in clinical pharmacology in general and drug development in particular. In February 1999 the US Food and Drug Administration issued a 'Guidance for Industry: Population Pharmacokinetics' that sets out the mechanisms and philosophy of PPK and outlines its role in drug development. The application of PPK to the drug development process plays an important role in the efficient development of safe and effective drugs. PPK knowledge is essential for mapping the response surface, explaining subgroup differences, developing and evaluating competing dose administration strategies, and as an aid in designing future studies. The mapping of the response surface is done to maximise the benefit-risk ratio, so that the impact of the input profile and dose magnitude on beneficial and harmful pharmacological effects can be understood and applied to individual patients. PPK combined with simulation methods provides a tool for estimating the expected range of concentrations from competing dose administration strategies. Once extracted, this knowledge can be applied to labelling or used to assess various future study designs. PPK should be implemented across all phases of drug development. For preclinical studies, PPK can be applied to allometric scaling and toxicokinetic analyses, and is useful for determining 'first time in man' doses and explaining toxicological results. Phase I studies provide initial understanding of the structural model and the effect of possible covariates, and may later be used to evaluate PPK differences between patients and healthy individuals. Phase II studies provide the greatest opportunity to map the response surface. With these PPK models it is possible to gain an improved understanding of the role of the dose on the response surface and of the range of expected responses. In phase III and IV studies, PPK is implemented to further refine the PPK model and to explain unexpected responses. Planning for the implementation of PPK across all phases of drug development is necessary, as well as planning for individual PPK studies. Planning should include: defining important questions, identifying covariates and drug-drug interactions that need to be investigated, and identifying the applications and intended use of the model(s). The plan for each project must have a strategy for data management, data collection, data quality assurance, staff training for data collection, data analysis and model validation.

Animals↗
PubMed1992

Clinical economics: a method for prospective health resource data collection.

Information about the economic benefit of new drugs is becoming increasingly important for formulary considerations, reimbursement policies and related considerations. Although economic benefits of drugs have been analysed and reported, the economic benefits of drugs have rarely been examined in the course of randomised therapeutic trials. We designed a modular survey instrument, the Resource Utilisation Survey (RUS), to collect economic outcomes in prospective trials. A pilot test of the RUS was conducted using clinical trial methods in a study of nizatidine versus placebo in preventing ulcers induced by nonsteroidal anti-inflammatory drugs. The purpose of the pilot study was to evaluate the RUS instrument and corresponding study design issues in clinical trials for either acute or chronic diseases. With the lessons learned from the pilot study, the RUS has been used successfully in other ongoing clinical trials.

Economics, Pharmaceutical↗
PubMed1996

Coauthors' contributions to major papers published in the AJR: frequency of undeserved coauthorship.

OBJECTIVE: Over half of the major papers published in the American Journal of Roentgenology (AJR) have five or more coauthors. This project was designed to evaluate the specific contributions of coauthors and the prevalence of undeserved authorship in major papers from institutions in the United States. MATERIALS AND METHODS: Questionnaires were mailed to the first author of 275 major papers from institutions in the United States that were published in the AJR in 1992 and 1993. Questions focused on coauthors' contributions to research design, data collection, data analysis, and manuscript preparation, and on undeserving authorship. RESULTS: One hundred ninety-six (72%) of the surveys were returned. Ninety-nine percent of first authors, 75% of second authors, fewer than half of third authors, and one third of fourth authors and beyond were said to have contributed to at least three of the following: research design, data collection, data analysis, and manuscript preparation (p < .02). A strong correlation was indicated between authorship position and contribution (r = -.69, p < .001), with a mean overall contribution of 63 +/- 17% (mean +/- SD) for the first author, 20 +/- 12% for the second author, 10 +/- 7% for the third author, 7 +/- 6% for the fourth author, and 5 +/- 5% for all other authors. Coauthors were listed in decreasing order of contribution in 70% of articles. However, the last author was the second major contributor in 10% of articles with three or more authors. The incidence of "undeserved" coauthors increased from 9% on papers with three authors to 30% on papers with more than six authors (mean, 17%; r = .97; p < .001). Undeserved authorship was attributed largely to individuals who contributed only cases (29%) or who created a sense of obligation or fear in the first author (40%). Manuscripts were more likely to include an undeserved coauthor when the first author was a nontenured staff member (45%) than when he or she was tenured faculty (28%) (p < .02). When decision about authorship were made at project conception, there were fewer coauthors (3.9 versus 5.4, p < .02) and a lower incidence of manuscripts with undeserving coauthors (23% versus 47%, p < .01). The final manuscript was read by all coauthors in 80% of manuscripts, and all coauthors were thought to understand the manuscript to the extent they could publicly defend it in 78% of manuscripts. The most commonly cited reason that otherwise honest individuals accept undeserved authorship was academic promotion. CONCLUSION: Undeserved authorship is a common and serious problem that is motivated primarily by academic promotion policies. The first two authors are said to account for the preponderance of work in almost all major papers.

Authorship↗
PubMed2005

Generic HTML Form Processor: A versatile PHP script to save web-collected data into a MySQL database.

The customizable PHP script Generic HTML Form Processor is intended to assist researchers and students in quickly setting up surveys and experiments that can be administered via the Web. This script relieves researchers from the burdens of writing new CGI scripts and building databases for each Web study. Generic HTML Form Processor processes any syntactically correct HTML forminput and saves it into a dynamically created open-source database. We describe five modes for usage of the script that allow increasing functionality but require increasing levels of knowledge of PHP and Web servers: The first two modes require no previous knowledge, and the fifth requires PHP programming expertise. Use of Generic HTML Form Processor is free for academic purposes, and its Web address is www.goeritz.net/brmic.

Databases as Topic↗