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Biomedical subjects

G Rücker

Publications and source records attributed to G Rücker.

At least 19 recordsLinked to original sources
PubMed2006

Are KISS data representative of German intensive care units? Statistical issues.

OBJECTIVES: Data collected within the German nosocomial infection surveillance system KISS are recommended as reference data for judging nosocomial infection rates in German intensive care units (ICUs). It is unknown whether the KISS data tend to under- or overestimate the true infection incidence rates. In this article, methodological aspects of the SIR1 study on the incidence of nosocomial infections are discussed, with the aim of estimating unbiased incidence rates of nosocomial infections in interdisciplinary German ICUs and examining whether the KISS data are representative. METHODS: We discuss the following methodological issues: 1) Sample size estimation. 2) Stratified random sampling of German ICUs. 3) Investigation of seasonal effects. 4) Statistical modeling of incidence rates using a negative binomial regression model. 5) Comparison of weighted incidence rates with the standardized rate ratio (SRR). RESULTS: Random sampling proved difficult to realize in practice since many ICUs refused to participate, particularly those in small hospitals. Analysis was adjusted for hospital size. No seasonal trends were found in the KISS data. Due to marked differences between ICUs, the number of infections is over-dispersed compared to a Poisson model, so negative binomial regression was used. Fifty ICUs were observed for two consecutive months each, corresponding to 21,832 patient days, during which 262 infections occurred. Infections were more frequent in large hospitals. The incidence rates provided by the SIR study are on average (SRR) 1.89 (1.63-2.20) times as large as those estimated by the KISS system. CONCLUSION: For estimating nosocomial infection incidence rates, random sampling and statistical modeling of over-dispersion were successfully performed. The study provides evidence that the KISS surveillance system tends to underestimate the true incidence rates of nosocomial infections in German ICUs.

Binomial Distribution↗
PubMed2005

Low-dose aspirin for secondary cardiovascular prevention - cardiovascular risks after its perioperative withdrawal versus bleeding risks with its continuation - review and meta-analysis.

OBJECTIVES: Low-dose aspirin given for secondary prevention of cardiovascular disease is frequently withdrawn prior to surgical or diagnostic procedures to reduce bleeding complications. This may expose patients to increased cardiovascular morbidity and mortality. Aim of the study was to review and quantify cardiovascular risks because of periprocedural aspirin withdrawal and bleeding risks with the continuation of aspirin. METHODS: We screened MEDLINE (January 1970-October 2004) with additional manual cross-referencing for clinical studies, surveys on the opinions of doctors and guidelines. RESULTS: Studies reporting the relative risk of acute cardiovascular events after aspirin withdrawal when compared with its continuation were not found. However, retrospective investigations revealed that aspirin withdrawal precedes up to 10.2% of acute cardiovascular syndromes. The time interval between discontinuation and acute cerebral events was 14.3 +/- 11.3 days, 8.5 +/- 3.6 days for acute coronary syndromes, and 25.8 +/- 18.1 days for acute peripheral arterial syndromes (P < 0.02 versus acute coronary syndromes). On aspirin-related bleeding risks, we obtained 41 (12 observational retrospective, 19 observational prospective, 10 randomized) studies, reporting on 49 590 patients (14 981 on aspirin). Baseline frequency of bleeding complications varied between 0 (skin lesion excision, cataract surgery) and 75% (transrectal prostate biopsy). Whilst aspirin increased the rate of bleeding complications by factor 1.5 (median, interquartile range: 1.0-2.5), it did not lead to a higher level of the severity of bleeding complications (exception: intracranial surgery, and possibly transurethral prostatectomy). Surveys amongst doctors on the management of this problem demonstrate wide variations. Available guidelines are scarce and in part contradictory. CONCLUSIONS: Only if low-dose aspirin may cause bleeding risks with increased mortality or sequels comparable with the observed cardiovascular risks after aspirin withdrawal, it should be discontinued prior to an intended operation or procedure. Controlled clinical studies are urgently needed.

Acute Disease↗
PubMed2002

[Freiburg intervention program for ambulatory therapy of obesity in childhood (FITOC)].

In this study we first try to answer the question, whether it is possible to make a successful treatment for obese children in an interdisciplinary program. Second it is asked whether a transfer of this program to further regions in Germany leads to comparable results. In FITOC children from the age of 8-11 years and over the 97. BMI-percentile are integrated in this program. The goals weight management, increased physical fitness and improvement of the cardiac risk profile are checked by weight, height, fasting blood serum, a standardized cycle ergometry and a medical measurement at the beginning, after treatment and at all check-ups. The recorded medical data show clearly that the intervention leads to a significant improvement in almost all checked parts. The successful treatment can be recorded after 8 months, likewise after 2.5 years as a long-term result. The further cornerstones of FITOC nutrition and psychology are not subject of this publication. In future the psychological part in FITOC will be evaluated by standardized inventories. The group from Düren has a success in therapy according to the definition of the program. Thereby it is shown that FITOC is extendable, if teams are trained intensively and the conditions are comparable. FITOC is able to treat obese children successfully over a long period of time. In consideration of the rising prevalence of obesity in childhood and the limited financial resources in health care this outpatient interdisciplinary program is an effective choice of treatment.

Child↗
PubMed2001

Synthesis of the beta-D-glucuronides of 2,3-, 3,4-, and 2,6-dichlorophenol.

The beta-D-glucuronides of 2,3-, 3,4-, and 2,6-dichlorophenol (1-3) were prepared by a modified Koenigs-Knorr synthesis. As the alkaline hydrolysis of perpivaloylated methyl (2,3-dichlorophenyl)-glucuronate 1a led to a dehydrated glucuronide, the preparation of peracetylated methyl dichlorophenylglucuronates with subsequent cleavage of the ester bindings under mild conditions was preferred.

Butanols↗
PubMed2001

Influence of right ventricular pre- and afterload on right ventricular ejection fraction and preload recruitable stroke work relation.

When right ventricular (RV) afterload is abnormally increased, it correlates inversely with right ventricular ejection fraction (RVEF). We tested, whether this would be different with normal afterload. Additionally, we investigated whether previous studies on the slope of RV preload recruitable stroke work (SW) relation, which used rather non-physiological measures to change RV preload, could be transferred to more physiological loading conditions. RV volumes were determined by thermodilution in 16 patients with stable coronary artery disease and normal pulmonary artery pressure (PAP) at rest. Pre- and afterload were varied by body posture, nitroglycerin (NTG) application and by exercise at different body positions. At rest, the change from recumbent to sitting position decreased PAP, cardiac index (Ci), RV diastolic and systolic volumes, and RVEF. Additionally, mean pulmonary artery pressure (MPAP) correlated positively with both RVEF and cardiac index. After correction for mathematical coupling, the RV preload recruitable SW relation was: right ventricular stroke work index (RVSWi) (103 erg m-2)= 8.1 x (RV end-diastolic volume index -4.9), with n=96, r=0.57, P< or =0.001. Exercise abolished this correlation and led to an inverse correlation between RV end-systolic volume (ESV) and RVSW. In conclusion, (i) RVEF correlates positively with RV afterload when afterload varies within normal range; (ii) the slope of the RV preload recruitable SW relation, which is obtained at steady state under normal loading conditions, is substantially flatter than previously described for dynamic changes of RV preload. With increasing afterload, preload loses its determining effect on RV performance, while afterload becomes more important. This puts earlier assumptions of an afterload independent RV preload recruitable SW relation into question.

Aged↗
PubMed1997

Allergenic sesquiterpene lactones from Eupatorium cannabinum L. and Kaunia rufescens (Lund ex de Candolle).

From Eupatorium cannabinum L., a hitherto unknown alpha-methylene-gamma-butyrolactone, 3 beta-peroxyeucannabinolide, was isolated. This compound and eupatoriopicrin from the same plant showed a weak sensitizing capacity in guinea pigs. 2-oxoludartin and dehydroleucodin, isolated from Kaunia rufescens (syn. Eupatorium rufescens), were strong sensitizers in the same sensitizarian procedure.

Allergens↗
PubMed1996

Detection of apoptosis in KG-1a leukemic cells treated with investigational drugs.

Four investigational drugs, p-benzoquinone, primine, miconidine acetate, and artesunate (dihydroqinghaosusuccinate), with growth inhibitory activity against flagellatae (e.g. trypanosoma, leptomonas, plasmodium) were investigated for their capability to induce programmed cell death (apoptosis) in human KG-1a leukemic cells. The results were compared with those of three well established cytostatic agents (cisplatin, daunorubicin, cytosine-arabinoside) and ionizing radiation. The antitumor activity of the drugs was validated by a cellular growth inhibition assay. The depletion of glutathione by these four investigational drugs favours the hypothesis that formation of free radicals and subsequent DNA strand breaks may be critical mechanisms of action and that the glutathione redox cycle is involved in detoxification of these reactive molecules.

Antineoplastic Agents↗
PubMed1993

[Molluscacidal activity of spiro-alpha-methylene-gamma-butyrolactone].

The alpha-methylene-gamma-butyrolactones 1-28 were tested in vitro for molluscicidal activity against Biomphalaria glabrata. The racemic compound 25 shows the best activity. The synthesis was carried out by modified Reformatzky reaction of the corresponding carbonyl compounds and bromomethylacrylic acid ethyl ester. 7-10, 17 and 22-27 have been synthesized for the first time.

4-Butyrolactone↗
PubMed1993

Triterpenoid glycosides from Stauntonia hexaphylla.

On the basis of spectroscopic and chemical methods, the structures of two new bisdesmosidic triterpenoid glycosides, named staunoside D and E, which were isolated from Stauntonia hexaphylla, were established as 3-O-(beta-D-glucopyranosyl(1-->2)-[beta-D- glucopyranosyl(1-->3)]-beta-D-glucopyranosyl)-hederagenin-28- O-[beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosyl] ester and 28-O-[alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl]ester, respectively. Three known triterpenoid glycosides were also isolated. A new proglycoside was isolated from the cleavage of the ester-glycosidic linkage and its structure characterized.

Carbohydrate Sequence↗
PubMed1993

Triterpenoid glycosides from Stauntonia hexaphylla.

From Stauntonia hexaphylla, two new 3,28-bisglycosidic triterpenoid glycosides named staunosides A and B, were isolated along with three known triterpenoid glycosides, one of which was isolated from nature of the first time, though it had previously been obtained from the acid hydrolysate of kizuta saponin K12. On the basis of chemical and physicochemical evidence, the structures of staunosides A and B were elucidated as 3-O-(beta-D-glucopyranosyl)-hederagenin-28-O-[beta-D- glucopyranosyl(1-->6)-beta-D-glucopyranosyl]ester and 28-O-[alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)- beta-D-glucopyranosyl]ester, respectively.

Carbohydrate Sequence↗
PubMed1992

[Synthesis of metabolites and enantiomers of prolintane].

The synthesis of 15 possible metabolites of prolintane (1) (Katovit) which is used in the treatment of blood pressure disregulations is described. Furthermore, the preparation of the enantiomers of 1 is reported, starting with R-(+)- and S-(-)-phenylalaninol respectively.

Pyrrolidines↗
PubMed1992

Acetylenic glucosides from Microglossa pyrifolia.

From the leaves of Microglossa pyrifolia Lam. (Asteraceae) four new acetylenic glucosides (1-4) have been isolated. The aglucones 2a and 4a are new polyynes. The aglucone 3a could only be isolated as a mixture of E/Z-isomers in a ratio of 4:1. The structures of 1-4 were elucidated by spectroscopic and biochemical methods. Compound 1 shows antibacterial activity.

Anti-Infective Agents↗
PubMed1992

Study on the metabolism of racemic prolintane and its optically pure enantiomers.

1. Asian and European volunteers were given racemic prolintane, and the metabolites in the 24 h urine were identified and quantified by g.l.c. mass spectroscopy using synthetic reference compounds. 2. R-(+)- and S-(-)-prolintane were synthesized from optically active phenylalanine. The metabolism of the enantiomers differs mainly in the quantitative amounts of metabolites.

Adult↗
PubMed1991

On using the adjacency matrix power method for perception of symmetry and for isomorphism testing of highly intricate graphs.

A modification of the adjacency matrix power method described recently for the perception of symmetry in graphs is introduced, which expands the limits of the method far beyond the realm of chemically interesting graphs. The procedure finds the automorphism partition even for intricate graphs without performing a tree search. The calculation effort increases with the problem size polynomially for all tested cases, including strongly regular graphs, two-level regular graphs, and graphs corresponding to balanced incomplete block designs (BIBD). An equally powerful computer program for testing isomorphism of graphs based on the adjacency matrix power method is introduced.

Chemical Phenomena↗