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Biomedical subjects

Oliver Kuss

Publications and source records attributed to Oliver Kuss.

8 recordsLinked to original sources
PubMed2003

Age-dependent depression in circulating endothelial progenitor cells in patients undergoing coronary artery bypass grafting.

OBJECTIVES: The effect of patient age on circulating endothelial progenitor cells (EPCs) and their mobilization during coronary artery bypass grafting (CABG) was assessed. BACKGROUND: The EPCs are able to contribute to reparative neovascularization after tissue ischemia. In experimental models, reparative neovascularization is impaired in senescent animals, but the role of EPCs in this impairment, especially in humans, is unknown. METHODS: In 50 consecutive patients (43 to 80 years old) with stable coronary artery disease undergoing CABG, the numbers of EPCs and the plasma levels of interleukin (IL)-6, IL-8, IL-10, and IL-18, as well as vascular endothelial growth factor (VEGF) and placental growth factor, were determined preoperatively, after coming off bypass, and 6, 12, 24, and 72 h postoperatively. RESULTS: Preoperative values of EPCs were lowered with increasing age, similar to the lowering of plasma VEGF levels. These age-associated decreases could not be explained by differences in atherosclerotic risk factors or cardiac function. Bypass surgery induced a rapid mobilization in EPCs, IL-6, IL-8, IL-10, and VEGF, with a peak 6 h postoperatively. Persistently lower levels of EPCs and VEGF throughout the observation period were observed in patients >69 years old, which could not be explained by differences in the operative procedure or inflammatory IL activation. CONCLUSIONS: Despite a significant increase in EPCs and release of cytochemokines during CABG, age is a major limiting factor for mobilization of EPCs. Further studies are necessary to improve the strategies for mobilization, ex vivo expansion, and re-transplantation of EPCs in aging patients.

Adult↗
PubMed2002

Global goodness-of-fit tests in logistic regression with sparse data.

The logistic regression model has become the standard analysing tool for binary responses in medical statistics. Methods for assessing goodness-of-fit, however, are less developed where this problem is especially pronounced in performing global goodness-of-fit tests with sparse data, that is, if the data contain only a small numbers of observations for each pattern of covariate values. In this situation it has been known for a long time that the standard goodness-of-fit tests (residual deviance and Pearson chi-square) behave unsatisfactorily if p-values are calculated from the chi(2)-distribution. As a remedy in this situation the Hosmer-Lemeshow test is frequently recommended; it relies on a new grouping of the observations to avoid sparseness, where this grouping depends on the estimated probabilities from the model. It has been shown, however, that the Hosmer-Lemeshow test also has some deficiencies, for example, it depends heavily on the calculating algorithm and thus different implementations might lead to different conclusions regarding the fit of the model. We present some alternative tests from the statistical literature which should also perform well with sparse data. Results from a simulation study are given which show that there exist some goodness-of-fit tests (for example, the Farrington test) that have good properties regarding size and power and that even outperform the Hosmer-Lemeshow test. We illustrate the various tests with an example from dermatology on occupational hand eczema in hairdressers.

Beauty Culture↗
PubMed2002

Induction of endotoxin tolerance improves lung function after warm ischemia in dogs.

In shock models, induction of endotoxin tolerance (ET) is known to have a protective effect. The present study was designed to explore if ET is effective in protecting lungs from reperfusion injury. Twelve foxhounds were used as experimental animals. After a left thoracotomy, the left hilum was clamped for 3 h, followed by 8 h of reperfusion. In the treatment group (ET, n = 6), dogs were pretreated with incremental daily endotoxin doses of up to 60 microg/kg on day 6. The ischemia and reperfusion experiment was carried out on day 9. Control group animals (n = 6) were not subjected to endotoxin. After 8 h of observation, functional parameters of the reperfused lung of the ET and the control group were statistically different (P < 0.05) with respect to Po(2) [ET vs. control: 172.7 +/- 12.9 vs. 66.1 +/- 7.2 (SE) mmHg], compliance (16.0 +/- 1.2 vs. 8.3 +/- 1.0 ml/0.1 kPa), and the wet-to-dry ratio (9.4 +/- 0.8 vs. 16.7 +/- 1.2). After 3 h of warm ischemia and 8 h of reperfusion, pulmonary function and lung water content improved in the endotoxin-tolerant group.

Animals↗
PubMed2002

Pulmonary blood flow is inhomogeneously reduced after Euro Collins-preservation and lung transplantation.

BACKGROUND: Vasoconstriction after lung transplantation is a well-known phenomenon, but only limited information is available on blood flow distribution after ischemia and reperfusion. The aim of our study was to determine the regional flow characteristics in transplanted and native dog lungs after 24 hours of cold storage and preservation with Euro Collins-solution. METHODS: Six pairs of weight-matched Foxhounds (25 to 30 kg) were used. In donors and recipients, aortic and pulmonary artery catheters were inserted percutaneously and a reference withdrawal catheter was placed into the main pulmonary artery. For preservation, the lungs were perfused with modified Euro Collins-solution and stored at 4 degrees C. After 24 hours, the left lung was transplanted. Regional pulmonary blood flow was assessed by injection of colored microspheres into the right atrium using the reference withdrawal technique. Measurements of regional pulmonary blood flow were conducted twice in donors and recipients (baseline and 3 hours after reperfusion). Tissue samples from five distinct regions (apical, medial, dorsal, ventral, and lateral) were taken to assess regional pulmonary blood flow and wet-dry ratios. RESULTS: The relative (per thousand Confidence Intervals/100 mg dry weight) regional pulmonary blood flow was significantly reduced in the transplanted lung but not in the native organ. This reduction was most pronounced in apical regions and smallest in regions close to the hilum. Edema formation occurred in both lungs, as judged from wet-to-dry ratios of lung tissue specimen. CONCLUSIONS: Two separate processes can be observed after single lung transplantation: (1) reduced regional pulmonary blood flow, which is a regional phenomenon restricted to the transplanted organ, and (2) extensive edema affecting both the transplanted and the native lung.

Animals↗
PubMed2002

Importance of irritant contact dermatitis in occupational skin disease.

BACKGROUND: Irritant contact dermatitis (ICD), provoked by work materials or workflows, is believed to be a frequent cause of occupational skin disease (OSD). Data of incidence rates of ICD within different occupations are inadequate. OBJECTIVE: We conducted a population-based study to identify occupational groups at risk for irritant and allergic contact dermatitis (ACD). METHODS: The data are based on all workers' compensation claims reported to our register of OSDs in Northern Bavaria [Berufskrankheitenregister Haut-Nordbayern (BKH-N)], Germany. RESULTS: From 1990 to 1999, 5285 patients had their cases completely assessed and recorded by government-employed physicians. We calculated the incidence rates of ICD and ACD in various occupations, divided into 24 occupational groups, in co-operation with the German State Institute of Labor and Occupation; there were a known total number of employees in each of the occupations. In these groups 3097 (59%) patients with OSD were observed, with an overall annual incidence rate of 4.5 patients per 10,000 workers for ICD, compared with 4.1 patients per 10,000 workers for ACD. The highest ICD annual incidence rates were found in hairdressers (46.9 per 10,000 workers per year), bakers (23.5 per 10,000 workers per year), and pastry cooks (16.9 per 10,000 workers per year); at the same time ICD was the main diagnosis of OSD in pastry cooks (76%), cooks (69%), food processing industry workers and butchers (63%), mechanics (60%), and locksmiths and automobile mechanics (59%). The results of a questionnaire showed frequent skin contact with detergents (52%), disinfectants (24%), and acidic and alkaline chemicals (24%) in the workplace. CONCLUSION: Based on the incidence data of the BKH-N, this study identified occupational groups with a high risk of ICD. Different frequencies of ICD and ACD within a single group are demonstrated. The frequent usage of detergents is being addressed because of the introduction of German legislation of recent date (the Approved Code of Practice 531 on 'wet work').

Adult↗
PubMedDate not supplied

Empirical studies assessing the quality of health information for consumers on the world wide web: a systematic review.

CONTEXT: The quality of consumer health information on the World Wide Web is an important issue for medicine, but to date no systematic and comprehensive synthesis of the methods and evidence has been performed. OBJECTIVES: To establish a methodological framework on how quality on the Web is evaluated in practice, to determine the heterogeneity of the results and conclusions, and to compare the methodological rigor of these studies, to determine to what extent the conclusions depend on the methodology used, and to suggest future directions for research. DATA SOURCES: We searched MEDLINE and PREMEDLINE (1966 through September 2001), Science Citation Index (1997 through September 2001), Social Sciences Citation Index (1997 through September 2001), Arts and Humanities Citation Index (1997 through September 2001), LISA (1969 through July 2001), CINAHL (1982 through July 2001), PsychINFO (1988 through September 2001), EMBASE (1988 through June 2001), and SIGLE (1980 through June 2001). We also conducted hand searches, general Internet searches, and a personal bibliographic database search. STUDY SELECTION: We included published and unpublished empirical studies in any language in which investigators searched the Web systematically for specific health information, evaluated the quality of Web sites or pages, and reported quantitative results. We screened 7830 citations and retrieved 170 potentially eligible full articles. A total of 79 distinct studies met the inclusion criteria, evaluating 5941 health Web sites and 1329 Web pages, and reporting 408 evaluation results for 86 different quality criteria. DATA EXTRACTION: Two reviewers independently extracted study characteristics, medical domains, search strategies used, methods and criteria of quality assessment, results (percentage of sites or pages rated as inadequate pertaining to a quality criterion), and quality and rigor of study methods and reporting. DATA SYNTHESIS: Most frequently used quality criteria used include accuracy, completeness, readability, design, disclosures, and references provided. Fifty-five studies (70%) concluded that quality is a problem on the Web, 17 (22%) remained neutral, and 7 studies (9%) came to a positive conclusion. Positive studies scored significantly lower in search (P =.02) and evaluation (P =.04) methods. CONCLUSIONS: Due to differences in study methods and rigor, quality criteria, study population, and topic chosen, study results and conclusions on health-related Web sites vary widely. Operational definitions of quality criteria are needed.

Evaluation Studies as Topic↗