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Biomedical subjects

R Böhm

Publications and source records attributed to R Böhm.

At least 19 recordsLinked to original sources
PubMed2002

Measurement of the beam-helicity asymmetry in the p((-->)e,e'p)pi(0) reaction at the energy of the Delta(1232) resonance.

In a p((-->)e,e'p)pi(0) out-of-plane coincidence experiment at the three-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q(2) = 0.2(GeV/c)(2). The results are in disagreement with three up-to-date model calculations. This is interpreted as a lack of understanding of the nonresonant background, which in dynamical models is related to the pion cloud.

Journal Article↗
PubMed2002

Prediction of response to hormonal treatment in metastatic breast cancer.

Prediction of outcome and individualization of therapeutic strategies are challenging problems in oncology. Predictive parameters for response to hormonal treatment include the expression of hormone receptor, the extent and location of metastatic spread, disease-free interval, patient age, response to prior hormonal therapy, grading, and more recently, some molecular markers like the expression of HER-2/neu. The use of conventional statistics for prediction of response to hormonal treatment is limited by non-linearities and complex interactions between predictive factors. Modern computational mathematical models like artificial neural networks, entropy-based inductive algorithms or chi(2) interaction detection algorithms can describe these interactions and generate classification models and decision structures. They can be used to predict the clinical outcome for individual patients. In contrast to conventional methods, the level of confidence for the predictions can reach 90% and more. This might be an important step towards further individualization of therapeutic strategies.

Antineoplastic Agents, Hormonal↗
PubMed2001

Neutral pion threshold production at Q(2) = 0.05 GeV(2)/c(2) and chiral perturbation theory.

New data are presented on the p(e,e'p)pi(0) reaction at threshold at a four-momentum transfer of Q(2) = 0.05 GeV(2)/c(2). The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4 MeV above threshold. Combined with measurements at three different values of the virtual photon polarization epsilon, the structure functions sigma(T), sigma(L), sigma(TT), and sigma(TL) are determined. The results are compared with calculations in heavy baryon chiral perturbation theory and with a phenomenological model. The measured cross section is significantly smaller than both predictions.

Journal Article↗
PubMed2001

Measurement of the recoil polarization in the p(e-->, e'p-->)pi(0) reaction at the Delta(1232) resonance.

The recoil proton polarization has been measured in the p(e-->,e'p-->)pi(0) reaction in parallel kinematics around W = 1232 MeV, Q2 = 0.121 (GeV/c)2, and epsilon = 0.718 using the polarized cw electron beam of the Mainz Microtron. All three proton polarization components, Px/P(e) = (-11.4+/-1.3+/-1.4)%, P(y) = (-43.1+/-1.3+/-2.2)%, and P(z)/P(e) = (56.2+/-1.5+/-2.6)%, could be measured simultaneously. The Coulomb quadrupole to magnetic dipole ratio, CMR = (-6.4+/-0.7(stat)+/-0.8(syst))%, was determined from Px in the framework of the Mainz Unitary Isobar Model. The consistency among the reduced polarizations and the extraction of the ratio of longitudinal-to-transverse response is discussed.

Journal Article↗
PubMed2000

The role of ferrioxamine E in pre-enrichment medium for determining Salmonella in environmental samples according to ISO method.

The effect of a siderophoric compound, ferrioxamine E, in the pre-enrichment broth on determining of Salmonella infantis in environmental samples was tested with combination of various pre-enrichment times and enrichment temperatures of 37 and 43 degrees C. Ferrioxamine E slightly improved the determination efficiency of this bacterium but the pre-enrichment time could not be reduced below 17 hours. The enrichment temperature of 43 degrees C was better than of 37 degrees C. The mixing ratios of 1:100 or 1:1000 for samples and pre-enrichment broth were more successful than the ratio of 1:10 as recommended by ISO.

Animals↗
PubMed2000

[Microbial contamination in human and animal drinking water].

Water plays an important roll in the epidemiology of a lot of infectious diseases. Groundwater as well as surface water contains generally microorganisms of several species, which cannot always differentiated properly in autochthonous flora and contaminants with health significance. Sources of bacterial or viral contaminants may be feces from man and/or animals but with different counts in ground and surface water. With respect to water used for supplying farm animals it is stated that it must have initially drinking water quality. Since it generally looses this quality in this supply system the following requirements shall be met: Free of Salmonellas and/or Campylobacter in 100 ml, no E. coli in 10 ml, total bacterial count at 37 degrees C less than 1000 cfu/ml and total bacterial count at 20 degrees C less than 10,000 cfu/ml.

Animals↗
PubMed1999

Polymerase chain reaction-ELISA to detect Bacillus anthracis from soil samples-limitations of present published primers.

A polymerase chain reaction (PCR)-ELISA technique to detect Bacillus anthracis from soil samples has been developed. The application of streptavidine-coated microtitre plates as well as plates covered with covalently linked oligonucleotides as catching probes led to a test sensitivity of about 100 fg pure genomic DNA or of less than 10 spores seeded into 100 g soil material. Some non-suspicious soil samples collected from different locations yielded positive results with presently published primers or probes targeting the B or C gene of pX02 and with primers targeting the chromosomal sequence B813. The former PCR products were sequenced. The number and mode of base exchanges led to the assumption that there will exist at least one unknown soil organism with high similarity within highly conserved capsule-encoding genes.

Amino Acid Sequence↗
PubMed1999

[The use of molecular fingerprinting techniques in environmental hygiene].

The analysis of epidemiological pathways for the transmission of pathogens via the environment is a fundamental task in the field of environmental hygiene. The task demands for a precise differentiation between isolates. This can be done by sophisticated techniques for differentiation which are based on phenotypic or genotypic features. The fingerprinting of DNA is a powerful tool in this context. A survey is given for different kinds of RFLP-analysis, plasmid profiling, and PCR fingerprinting as well regarding their principles, methodical variations and published applications. Notable limitations of the applications are also discussed.

Animal Diseases↗
PubMed1999

[Detection of airborne cultivatable microorganisms from compost sites--emissions and imissions].

The statement presented here gives an overview and assessment of the procedures and concepts currently used for the collection and determination of airborne, culturable microorganisms at sources of emission within composting plants and in their near vicinity. The paper focuses on "classical" methods, which involve cultivation as an intermediate step for the determination of viable, airborne microorganisms. The theoretical and practical requirements on such methods are discussed. Results and experiences from recent investigations are described.

Air Microbiology↗
PubMed1999

[Microbial emissions in collection of residential garbage].

Two exemplary investigations with different questions were carried out in Munich and Stuttgart by sampling bio-aerosols due to and during the collection and emptying of different types of waste bins. The emissions were regarded qualitatively and quantitatively, in order to answer the question, whether and to which amount differences of bio-aerosol emissions occurred due to the kind of wastes collected. The lowest emissions of airborne microorganisms were found during the collection of the paper waste fraction. In comparison, the amounts of them during the collection of unseparated household wastes as well as source separated bio-wastes and the remaining residual waste fraction were higher. Between the three latter, no significant differences could be found, only a tendency of higher values for the thermotolerant mould A. fumigatus during the collection of bio- and residual wastes was observed. Maybe this was caused by special features of the different sampling locations, but it could also be due to the longer collection intervals (bio- and residual wastes were partially collected every two weeks, unseparated wastes every week).

Air Microbiology↗
PubMed1998

Suitability of repetitive-DNA-sequence-based PCR fingerprinting for characterizing epidemic isolates of Salmonella enterica serovar Saintpaul.

Three molecular typing methods, repetitive-sequence-based PCR (rep-PCR) fingerprinting, plasmid profiling, and arbitrarily primed PCR fingerprinting, were used to characterize isolates of Salmonella enterica serovar Saintpaul. Most of the isolates were obtained from epidemic human cases of food-borne salmonellosis, together with some from the food material suspected to be the source of infection, and a few were obtained from other cases apparently not related to the epidemic. All three methods adequately discriminated the epidemic strain from other strains of the serovar. In addition several isolates from human cases which are not identical to the epidemic strain were found. These isolates therefore must have been responsible for some sporadic infections, which were only temporally related to the epidemic. These strains showed a high degree of similarity to a strain isolated from a turkey. rep-PCR fingerprinting with REP-Dt primers and primer ERIC1R, applicable even to crude cell lysates, offers an attractive choice as a primary method for the discrimination of various Salmonella serotypes as well as isolates within serotype Saintpaul.

Bacterial Typing Techniques↗
PubMed1997

Fetal adrenal transplantation: success of a laparoscopic technique in rats.

BACKGROUND/PURPOSE: The present study investigates a new laparoscopic technique for fetal adrenal transplantation in rats. RESULTS: The procedure was successful in 9 of 10 cases (one hole in the omentum) with no postoperative complications. On examination 4 weeks postoperatively, all but one graft showed macroscopic integrity, vascular supply, and histological maturation to normal zonal differentiation. When bilateral adrenalectomy was performed in the recipient to assess endocrine competence of the fetal adrenal grafts, survival was prolonged and Addison crisis was prevented in the animals that underwent transplantation. Levels of aldosterone dropped within the first week after adrenalectomy, but recovered steadily. Analysis of corticosterone demonstrated that levels fell to 25% of sham operated rats in the first week, but then steadily climbed to 70%. CONCLUSIONS: To the authors' knowledge this report presents the first study for laparoscopic transplantation of fetal tissues. Laparoscopic transplantation of fetal adrenal glands seemed feasible and successful in rats. The fetal adrenal transplants matured and served for a prolonged survival.

Addison Disease↗
PubMed1997

Ketone body metabolism in the Carp Cyprinus carpio: biochemical and 1H NMR spectroscopical analysis.

In fed and starved carp, Cyprinus carpio, ketone body metabolism and those metabolic and endocrine factors that are known to induce ketogenesis in starving mammals were investigated. Acetoacetate was detected in plasma and liver of both fed and starved carp. We could not detect 3-hydroxybutyrate, neither by 1H-NMR spectroscopy nor by spectrophotometric assay, in spite of low activities of hepatic 3-hydroxybutyrate dehydrogenase. Starvation of carp did not create metabolic conditions that would favor ketone body synthesis: Mobilization and hepatic catabolism of fatty acids were only moderately enhanced, the rate of gluconeogenesis was not elevated, and glucagon levels as well as the glucagon/insulin-ratio remained stable or declined. Therefore, the discrepancy in the effect of food deprivation on mammalian and teleostean ketogenesis appears to be caused not by the absence of the ketogenic pathway from teleosts but by major differences between mammals and fish in their metabolic response to starvation.

Animals↗