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Biomedical subjects

Ralf Bender

Publications and source records attributed to Ralf Bender.

6 recordsLinked to original sources
PubMed2003

Helicobacter pylori and carcinogenesis of gastric B-cell lymphomas.

Primary non-Hodgkin's lymphomas of the stomach are associated with Helicobacter pylori infection. We analyzed gastric lymphoma onset data with respect to prior H. pylori infections based on the multistage theory of carcinogenesis. This theory provides a link between epidemiological data and biological processes. The study involved 133 patients, aged 29-75 years, diagnosed with marginal zone B-cell lymphoma (MZBL) and diffuse large cell B-cell lymphoma (DLBL). A 2-parametric Weibull model was applied to MZBL and DLBL onset data. Median age of diagnosis of MZBL (DLBL) was 59 years (55 years) in males and 65.5 years (64 years) in females. Infection with H. pylori was found in 81.3% (59.5%) of the patients diagnosed with MZBL (DLBL). Lymphoma latency data were fitted to Weibull distributions with a shape parameter of 5.7 for MZBL cases and 4.2 for DLBL. The shape parameter that indicates the number of steps in carcinogenesis was approximately independent of the status of infection with H. pylori in DLBL in contrast to MZBL. It was shown that gastric lymphoma onset data can be described by Weibull distribution functions. The findings support the hypothesis that MZBL and DLBL have different lines of development. There is indication of stronger antigen dependency in the carcinogenesis of MZBL in comparison to DLBL.

Adult↗
PubMed2003

Breastfeeding promotion in non-UNICEF-certified hospitals and long-term breastfeeding success in Germany.

AIM: To assess breastfeeding practices using the World Health Organization/United Nations Children's Fund (WHO/UNICEF) Ten Steps to Successful Breastfeeding for Baby-Friendly Hospitals in unselected non-UNICEF certified German hospitals and to examine the influences of breastfeeding promotion on long-term breastfeeding success as assessed by WHO criteria. METHODS: Information on the fulfilment of the Ten Steps was collected in 177 randomly chosen maternity hospitals by a postal questionnaire. Breastfeeding duration was assessed in 1487 mothers delivering in these hospitals. Multiple logistic regression was used to estimate the association between a low breastfeeding promotion index, defined as fulfilment of fewer than five steps, and the risk of short-term breastfeeding, less than 4 mo. RESULTS: A higher breastfeeding promotion index was not associated with early breastfeeding but was significantly associated with full breastfeeding at 4 and 6 mo. After adjusting for confounding factors, delivering in a hospital with a low breastfeeding promotion index was associated with an increased risk of short-term breastfeeding [odds ratio (OR) 1.24], although associations with maternal demographic variables (young age: OR 3.34), low educational level (OR 2.81) and upbringing in East Germany (OR 2.27) were stronger. CONCLUSION: In unselected German hospitals even moderate levels of breastfeeding promotion identified by WHO/UNICEF criteria were associated with long-term breastfeeding success.

Adult↗
PubMed2002

Body weight, blood pressure, and mortality in a cohort of obese patients.

The associations between body weight, raised blood pressure, and mortality remain controversial. The authors examined these relations by considering all degrees of obesity in the Düsseldorf Obesity Mortality Study (1961-1994). Among 6,193 obese German patients aged 18-75 years and having a body mass index (BMI) of > or =25 kg/m(2), 1,059 deaths were observed after a median follow-up of 14.8 years. The entire cohort was grouped into quartiles according to BMI (25-<32, 32-<36, 36-<40, > or =40 kg/m(2)) and systolic blood pressure (SBP) (<140, 140-<160, 160-<180, > or =180 mmHg). Cox proportional hazards analyses were performed to adjust for age. For women, the mortality risk curves for the four BMI groups in relation to SBP were flat without crossing, whereas the risk curve for moderately obese men (BMI 25-<32 kg/m(2)) crossed the risk curves for the higher BMI groups. In the group of patients with very high blood pressure (SBP > or = 180 mmHg), moderately obese subjects (BMI 25-<32 kg/m(2)) had a higher mortality risk for men when compared with the BMI group 32-<36 kg/m(2) (hazard ratio =1.62, 95% confidence interval: 1.0, 2.7) but not for women (hazard ratio = 0.71, 95% confidence interval: 0.4, 1.2). These findings support previous observations that the risk of death is lower for hypertensive men in high compared with low BMI groups.

Adolescent↗
PubMed2002

Calculating the "number needed to be exposed" with adjustment for confounding variables in epidemiological studies.

The number needed to treat (NNT) is a popular summary statistic to describe the absolute effect of a new treatment compared with a standard treatment or control concerning the risk of an adverse event. The NNT concept can be applied whenever the risk of an adverse event is compared between two groups; for the comparison of exposed with unexposed subjects in epidemiological studies, we propose the term "number needed to be exposed" (NNE). Whereas in randomized clinical trials NNT can be calculated on the basis of a simple 2 x 2 table, in epidemiological studies methods to adjust for confounders are required in most applications. We derive a method based upon multiple logistic regression analysis to perform point and interval estimation of NNE with adjustment for confounding variables. The adjusted NNE can be calculated from the adjusted odds ratio (OR) and the unexposed event rate (UER) estimated by means of an appropriate multiple logistic regression model. As UER is dependent on the confounders, the adjusted NNEs also vary with the values of the confounding variables. Two methods are proposed to take the dependence of NNE on the values of the confounders into account. The adjusted number needed to be exposed can be a useful complement to the commonly presented results in epidemiological studies, such as ORs and attributable risks.

Clinical Trials as Topic↗
PubMed2002

A new classification plot for the C-peptide suppression test.

CONTEXT AND OBJECTIVE: To evaluate the C-peptide suppression test as a screening test in patients with symptoms of hypoglycemia as compared to the standard fasting test. DESIGN: Retrospective discriminant analysis of data from C-peptide suppression tests. SETTING: Clinical study. PATIENTS: Patients with insulinomas and patients without insulinomas but having symptoms compatible with hypoglycemia. INTERVENTIONS: The results from C-peptide suppression tests of 26 patients with insulinomas and 100 patients without insulinomas were compared. MAIN OUTCOME MEASURES: A classification plot which introduces two discriminant parameters for the C-peptide suppression test: the ratio of [blood glucose]/[C-peptide] at the lowest C-peptide concentration and mean glycemia during insulin infusion. RESULTS: In patients with insulinomas, minimal serum C-peptide levels were higher (1.81+/- 0.87 ng/mL; median 1.83 ng/mL; maximal suppression 37 +/- 24% of basal C-peptide levels) as compared to patients without insulinoma (0.40 +/- 0.15 ng/mL; median 0.30 ng/mL; maximal suppression of 75 +/- 9%; P<0.001). Mean glycemia during the test was lower in patients with insulinomas (30.8 +/- 3.3 vs. 47.5 +/- 8.3 mg/dL; P<0.001) as was the [blood glucose]/[C-peptide] ratio (21.9 +/- 14.6 vs. 139.2 +/- 43.8; P<0.001). Discriminant analysis revealed a specificity of 96% to rule out the diagnosis of 'insulinoma' at a 1% probability threshold with a sensitivity of 100%. CONCLUSIONS: We developed a new classification plot for the C-peptide suppression test in order to accurately identify those patients whose symptoms of hypoglycemia are not due to endogenous hyperinsulinemia/insulinomas. Thus, the need for fasting tests and hospitalization costs can be reduced.

Adenoma, Islet Cell↗