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Biomedical subjects

M Fassbender

Publications and source records attributed to M Fassbender.

13 recordsLinked to original sources
PubMed2004

[Prevalence of anti-Yersinia antibodies in European brown hares in North-Rhine Westphalia, Germany].

Yersinia (Y.) pseudotuberculosis infections may lead to significant lethality in European brown hare (Lepus europaeus, Pallas) populations especially during the cold and wet seasons. In recent decades, also Y. enterocolitica was isolated from hares found dead. Consequently, a Western-blot technique proved to be valuable for the detection of antibodies against all pathogenic Yersinia isolates was applied to monitor the prevalence of antibodies in hare populations in North-Rhine Westphalia, Germany. A total of 89.6% of the 230 animals tested was seropositive. Further investigations should be performed to elucidate the role of subclinical yersiniosis in the decline of European brown hare populations in Germany.

Animals↗
PubMed2003

Seasonal timing of sperm production in roe deer: interrelationship among changes in ejaculate parameters, morphology and function of testis and accessory glands.

Roe deer are seasonal breeders with a short rutting season from mid-July to mid-August. The seasonality of reproductive activity in males is associated with cyclic changes between growth and involution of both testes and the accessory sex glands. This study characterizes morphological and functional parameters of these organs prior to, during and after breeding season in live adult roe deer bucks. Size and morphology of the reproductive tract was monitored monthly by transcutaneous (testes, epididymis) and transrectal (accessory glands) ultrasonography. Semen was collected by electroejaculation. Concentration, motility and morphological integrity of spermatozoa as well as the content of proteins and testosterone in semen plasma were evaluated. Proportions of haploid, diploid and tetraploid cells were estimated by flow cytometry in testicular tissue biopsies. Serum testosterone was measured by enzyme immunoassay. Most parts of the male reproductive tract showed distinct circannual changes in size and texture. These changes were most pronounced in the testes, seminal vesicles, and prostate. All reproductive organs were highly developed during the rut only. The volume of ejaculates, total sperm number and percentages of motile and intact spermatozoa also showed a maximum during this period and corresponded with high proportions of haploid cells in the testis. The highest percentages of tetraploid cells were found in the prerutting period. The production of motile and intact spermatozoa correlated with both the protein content of semen plasma and the concentration of testosterone in semen plasma and blood serum. These results suggest the importance of combined actions of the testes and accessory sex glands and the crucial role of testosterone in facilitating the optimal timing of intensified semen production to ensure sufficient numbers of normal spermatozoa in seasonal breeders.

Animals↗
PubMed2002

[Preoperative planning and surgical technic in achieving stability and leg length equality in total hip joint arthroplasty].

One of the prerequisites for a good outcome of total hip arthroplasty is preoperative planning. Using a roentgenogram, the size of an implant, incision level on the femoral neck, depth required for fitting the cup, restoration of the center of hip rotation and, if necessary, correction of length descrepancy between the legs are determined. The preoperative planning based on an X-ray image was introduced by M. E. Müller and, in 1976, was modified by R. Schneider who used a transparent sheet for a template on which all relevant points guiding the surgical procedure are marked, i.e., the right position for implantation of the cup and stem, and incision lines. In uncomplicated cases, however, this approach is not necessary and the "planning principle of parallel lines" developed by L. Spotorno in 1988 can be used instead. The determination of length discrepancy between the legs is derived from a drawing of three reference lines on the roentgenogram. The lines parallel to each other indicace the same length for both legs. If the legs differ in length, the lines will diverge from each other in a way typical for this condition.

Arthroplasty, Replacement, Hip↗
PubMed2001

The natBr(p,x) (73,75)Se nuclear processes: a convenient route for the production of radioselenium tracers relevant to amino acid labelling.

A possible route for the production of no-carrier-added (n.c.a.) 73Se (T(1/2) = 7.1 h) and 75Se (120 d) is introduced. D,L-2-Amino-4-([73Se]methyl-seleno) butanoic acid (D,L-[73Se]selenomethionine) with an overall radiochemical yield of > 40% could be prepared via a 3-step polymer-supported synthesis after successful separation of 73Se from KBr targets. Excitation functions for the natBr(p,x) (72,73,75)Se processes were measured from threshold up to 100 MeV utilizing pellets of pressed KBr. Targets were irradiated at the NAC cyclotron with proton beams having primary energies of 40.4, 66.8 and 100.9 MeV. The calculated 73Se yield (EOB) for 1 h irradiation in 1 microA of beam at the optimum proton energy range of 62-->42 MeV is 81.4 MBq (2.2 mCi), and the calculated 75Se yield (EOB) for the overall range 62 MeV-->threshold for the same irradiation conditions is 0.97 MBq (0.026 mCi).

Amino Acids↗
PubMed2001

Establishment of assisted reproduction technologies in female and male African wild dogs (Lycaon pictus).

Transrectal ultrasonography, electroejaculation and cryopreservation of spermatozoa were applied to the African wild dog (Lycaon pictus) to establish non-invasive protocols for assessing the reproductive health of one of the most endangered African canids. Transrectal ultrasonography was performed on immobilized male (n = 2) and female (n = 5) captive wild dogs. The testes and epididymides of the male dogs were imaged transcutaneously, followed by electrostimulation and cryopreservation of spermatozoa. The sonomorphology of the female and male urogenital tracts was characterized. In females, the vagina, cervix, non-pregnant uterus and ovary were imaged and the reproductive health of each female was evaluated. The sonographic assessment helped to identify one pyometra and extensive abdominal fat deposits in two other individuals in which pyometra had been suspected. Images of the adrenal glands showed differences in size among individuals of the same breeding group. Whether these differences were related to the dominance hierarchy remains to be determined. In males, visualization of the prostate gland, testis and epididymis indicated sexual maturity. Three ejaculatory fractions (1.0, 1.5 and 0.5 ml, with 50, 95 and 95% motility, respectively; 1.125 x 10(8) spermatozoa per ejaculate) were collected from one male. The motility of each of these fractions after thawing was 0, 30 and 40%, respectively. Electrostimulation of the second male, in which a cystic structure in a testis had been identified by sonography, resulted in an aspermic ejaculate (0.5 and 1.0 ml). These technologies provided basic data on reproduction in female and male African wild dogs and were an efficient way to evaluate reproductive health.

Adrenal Glands↗
PubMed1995

Genetically engineered mammalian cells and applications.

In general, cells genetically engineered for stable and defined expression of xenobiotic-metabolizing enzymes are useful tools whenever a metabolism-related problem in toxicology and pharmacology is to be solved. It is the genetic and phenotypic nature of a given cell that determines its applicability. Mammalian cells have useful characteristics not given in bacterial, yeast or insect cells, which also may express xenobiotic-metabolizing enzymes. It is the problem to be solved and the question to be answered which determine the optimal choice for the best-suited expression system. There may even be subtle differences between mammalian cells of different species and organ origin, which might play a role in choosing a mammalian expression system. Thus, the level and specificity of the xenobiotic-metabolizing enzyme, the experimental testing conditions, and the biological endpoints present in a chosen cell are the most important criteria to be observed in the application of the mammalian expression systems.

Animals↗
PubMed1994

Multiple-dose pharmacokinetics of sparfloxacin and its influence on fecal flora.

In a randomized, double-blind, placebo-controlled, multiple-dose pharmacokinetic study, the safety and effect on intestinal flora of sparfloxacin (SPX) were determined in 12 healthy male volunteers (8 received SPX and 4 received a placebo). Following fasting and oral administration of 400 mg on day 1 and 200 mg on days 2 to 8, concentrations of the free drug in serum, urine, and feces were measured by high-performance liquid chromatography; serum and urine were also evaluated by a microbiological assay. All results, except those for renal excretion, exclude the glucuroconjugate metabolite. A mean peak concentration in serum (400-mg dose) of 0.56 +/- 0.13 mg/liter was measured 3.52 +/- 0.98 h after administration. Pharmacokinetic parameters (measured by high-performance liquid chromatography) were based on an open, one-compartment model and resulted in the following day 1 (calculated for the 200-mg dose), day 4 (recalculated for a single dose), and day 8 values (mean +/- standard deviation): area under the curve, 16.4 +/- 2.3 (day 1) and 18.3 +/- 5.1 (day 4) mg.h/liter; elimination half-life, 18.3 +/- 3.9 h; steady-state volume of distribution, 4.7 +/- 1.4 (day 1) and 4.3 +/- 1.2 (day 8) liters/kg; apparent total clearance, 201 +/- 31 (day 1) and 190 +/- 51 (day 4) ml/min; renal clearance, 19.1 +/- 5.8 (day 1) and 23.2 +/- 19.4 (day 4) ml/min. Recovery in urine on day 1 was 5.89% +/- 1.4% of the dose in 24 h for the parent compound and 18.4% +/- 6.8% for the SPX glucuronide.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Comparative pharmacokinetics of the new oral cephalosporins.

The comparative pharmacokinetics of the new oral cephalosporins (ester and nonester types), together with that of the first generation carbacephem, loracarbef, are considered in healthy volunteers. Also in this review, pharmacokinetic and microbiological data are combined in order to predict the possible clinical efficacy of this group of agents. Despite apparent similarities in the structure of these agents, single dose studies have revealed marked differences in the pharmacokinetics of the oral cephalosporins. Multiple dose studies showed no evidence of accumulation with these agents. In the elderly, only minor changes in the pharmacokinetics of the oral agents were observed, and were insufficient to warrant dosage adjustment. Unlike that of the nonester compounds, the bioavailability of the ester cephalosporins is increased when they are administered after food. Variable effects are observed when the ester agents are coadministered with antacids or H2-antagonists; while the absorption of cefetamet pivoxil was unaffected by coadministered antacids or H2-antagonists, the absorption of cefpodoxime proxetil was reduced.

Administration, Oral↗
PubMed1993

Pharmacokinetics of new oral cephalosporins, including a new carbacephem.

This review analyzes the pharmacokinetics of new oral cephalosporins, including esters, non-esters, and the carbacephem loracarbef, in healthy volunteers, as described in the literature and evaluated in several studies of our own. Single-dose studies have demonstrated considerable pharmacokinetic differences among these compounds. Cefixime, cefpodoxime proxetil, and cefetamet pivoxil are characterized by a low peak concentration and a prolonged half-life, while the other new agents have higher peak levels and shorter half-lives. Except for cefixime, the new oral cephalosporins are eliminated mainly by the kidneys. Pharmacokinetic studies in the elderly and in children indicate that the bioavailability of these agents is not influenced by age. Food increases the bioavailability of the ester cephalosporins but does not affect the absorption kinetics of the other new drugs.

Administration, Oral↗
PubMed1992

Superoxide anion release induced by platelet-activating factor is increased in human alveolar macrophages from smokers.

This study was designed to investigate the effects of the platelet-activating factor (PAF) on the superoxide anion production (O2.) of human alveolar macrophages (AM) from nonsmoking (n = 18) and smoking (n = 30) subjects. Freshly isolated cells were stimulated with (PAF) or with a phorbol ester (phorbol 12-myristate 13 acetate (PMA)). Stimulation with PAF led to a dose-dependent increase of O2. production by AM in both groups. The median effective dose (EC50) for PAF action on O2. production of smoker AM was 0.5 x 10(-8) M, compared to nonsmoker AM with an EC50 of 1.0 x 10(-7) M. This effect of PAF was blockable by the PAF-antagonist WEB 2086 in a dose-dependent manner. Comparison of the relative increase of O2. production after PAF-stimulation showed that smoker cells were significantly more sensitive to PAF than nonsmoker cells (p less than 0.01). In contrast to the findings with PAF, the relative increase of O2. production after PMA-stimulation showed no differences between smoker and nonsmoker AM. Our data suggest that AM from smoking subjects are more sensitive to PAF than AM from nonsmokers.

Bronchoalveolar Lavage Fluid↗
PubMed1991

Regulation of the superoxide-forming NADPH oxidase of human neutrophils is not altered in essential hypertension.

Neutrophils possess a plasma-membrane-bound reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase which catalyzes superoxide (O2-) formation and is activated by a variety of stimuli. Recently, neutrophils of patients with essential hypertension (EHT) have been reported to generate O2- at rates up to fourfold higher than those of normotensive (NT) subjects upon exposure to the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMet-Leu-Phe). We studied regulation of O2- formation in neutrophils of 25 EHT subjects and 25 age- and sex-matched NT subjects. The intercellular signal molecules fMet-Leu-Phe, platelet-activating factor and leukotriene B4 activated O2- formation in neutrophils, but the latter two receptor agonists were less effective than the former. fMet-Leu-Phe activated O2- formation with a 50% effective concentration (EC50) of about 30 nmol/l, the effect of the chemotactic peptide being maximal at 0.1-1 mumol/l. fMet-Leu-Phe-induced O2- formation was potentiated by platelet-activating factor, adenosine 5'-[gamma-thio]triphosphate and cytochalasin B and was inhibited by the activators of adenylyl cyclase, isoproterenol, prostaglandin E1 and histamine. 4 beta-Phorbol 12-myristate 13-acetate, 1,2-dioctanoyl-sn-glycerol, gamma-hexachlorocyclohexane and arachidonic acid, which circumvent receptor stimulation, also activated O2- formation. Significant differences between NT and EHT subjects were not evident in respect of any of the parameters studied. Our data suggest that regulation of the neutrophil NADPH oxidase is not disturbed in EHT and that altered O2- formation does not represent a genetic marker for abnormalities in plasma-membrane signal transduction in EHT.

Adult↗
PubMed1988

Different effects of furosemide on alpha-adrenoceptors and on platelet aggregation in man.

The effect of a long-term administration of furosemide (2 x 30 mg/day for 3 weeks) on platelet alpha 2-adrenoceptor density and the fraction of high-affinity binding sites, as well as on platelet aggregation induced by adrenaline and ADP, was studied ex vivo in 8 normotensive volunteers. For comparison the in vitro effect of furosemide on platelet aggregation was also evaluated. Furosemide decreased alpha 2-adrenoceptor-density (P less than 0.01) and the fraction of high-affinity binding sites (P less than 0.05). Adrenaline-induced platelet aggregation was not altered ex vivo and in vitro. Furosemide inhibited ADP-induced platelet aggregation ex vivo (P less than 0.05) and in parallel in vitro (P less than 0.01) in a dose-dependent manner. The reduction of the density of alpha 2-adrenoceptors in the high affinity state may be of functional importance for the hemodynamic effects of furosemide. The inhibitory effect of furosemide on ADP-induced platelet aggregation ex vivo and in vitro, which is not related to the effects on adrenoceptors, seems to involve direct effects of furosemide on platelet function. It remains to be seen whether the latter effect is of clinical importance.

Adult↗