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Biomedical subjects

W Krause

Publications and source records attributed to W Krause.

At least 73 records · Page 4Linked to original sources
PubMed1999

The sensitivity of instantaneous coherence for considering elementary comparison processing. Part II: Similarities and differences between EEG and MEG coherences.

The EEG (electroencephalogram) coherence depends on EEG deviation type. A high level of sensitivity of instantaneous coherence for investigating elementary cognitive tasks could be shown in the case of unipolar reference (ear lobe reference). In order to validate of this result the same investigations were performed for MEG (magnetoencephalogram) coherence, where EEG and MEG were measured simultaneously. A strong correlation between time intervals with high EEG and MEG coherence could be shown. The equivalence of the sensitivity of EEG and MEG coherence for the description of the dynamic behaviour of information processing and the distinction between different elementary cognitive tasks is proven statistically.

Adult↗
PubMed1999

Application of pharmacokinetics to electron-beam tomography of the abdomen.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the pharmacokinetics of abdominal time-attenuation curves obtained at electron-beam tomography. MATERIALS AND METHODS: Computed tomographic enhancement data of the aorta, portal vein, vena cava, liver, spleen, and pancreas were obtained in 25 patients after injection of 50 mL of contrast medium. These data were used to calculate pharmacokinetic parameters such as half-lives, mean residence times, and areas under the curve with a computer program. RESULTS: Maximal enhancement was observed in the aorta 24 seconds +/- 5 (mean +/- standard deviation) after starting the injection of contrast medium (178 HU +/- 56), in the portal vein after 42 seconds +/- 14 (60 HU +/- 17), in the vena cava after 35 seconds +/- 7 (66 HU +/- 23), in the liver after 58 seconds +/- 15 (24 HU +/- 6), in the spleen after 35 seconds +/- 12 (42 HU +/- 16), and in the pancreas after 39 seconds +/- 15 (42 HU +/- 10). Half-lives of the last phase observed were 108 seconds +/- 123 in the aorta, 33 seconds +/- 30 in the portal vein, 49 seconds +/- 40 in the vena cava, 50 seconds +/- 54 in the liver, 62 seconds +/- 33 in the spleen, and 22 seconds +/- 27 in the pancreas. The computer program allowed for excellent fitting curves to the measured attenuation values and for subsequent calculation of pharmacokinetic parameters. New dosage regimens also could be simulated successfully. CONCLUSION: The pharmacokinetic parameters evaluated might be useful in the optimization of dosing and scanning parameters of the abdomen for ultrafast and helical CT.

Aorta, Abdominal↗
PubMed1999

CT blood pool enhancement in primates with lopromide-carrying liposomes containing soy phosphatidyl glycerol.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the feasibility of using iodinated liposomes as blood pool agents for computed tomography (CT) in nonhuman primates. MATERIALS AND METHODS: Five normal adult baboons (15-21 kg) were anesthetized and intravenously injected with iopromide containing soy phosphatidyl glycerol liposomes with a diameter of 195 nm. Each animal received a dose of 300 mg total iodine per kilogram (46% encapsulation). RESULTS: The animals tolerated the injections well, experiencing no measurable electrocardiographic changes, and recovered uneventfully from anesthesia. Sequential helical CT scans of the baboons from the base of the skull to the symphysis pubis acquired up to 40 minutes after injection showed persistent blood pool enhancement. Maximum mean enhancement of major vascular structures was 106 HU at 1 minute after contrast medium injection. Mean blood pool enhancement was 76, 72, and 67 HU at 10, 20, and 40 minutes after injection, respectively. Liver and spleen were enhanced by 40 and 41 HU, respectively, 40 minutes after injection. No significant enhancement was measured in the brain and pancreas. CONCLUSION: Soy phosphatidyl glycerol with iopromide liposomes produces prolonged vascular enhancement and has potential as a blood pool CT contrast agent in primates.

Animals↗
PubMed1999

[Haptic perception and EEG changes in anorexia nervosa].

OBJECTIVES: We predicted that due to diminished somatosensory integrative ability, the anorectic patients would have problems reproducing haptic stimuli. In addition we sought to determine whether EEGs from anorectic patients (AN) and the healthy controls (CO) would show discrepancies between the two groups during haptic explorations in theta-power over the right parietal region. METHOD: EEG power (theta-power) data of AN (n = 13) and CO (n = 13) were analyzed during haptic exploration tasks and rest intervals. The haptic explorations consisted of palpating the structure of six sunken reliefs in sequence with both hands, eyes closed. After each exploration the structure was drawn on a piece of paper. RESULTS: The reproductions of haptic stimuli submitted by the anorectic patients were of notably poorer quality than those of the healthy controls. During rest intervals and haptic explorations, spectral power was generally lower in the AN group in comparison to the healthy controls. Significant theta-power differences between groups showed over the right parietal cortex during haptic explorations. The decrease in EEG power in the anorectic patients in the theta bands across the right parietal region during haptic exploration tasks could be interpreted as a minor activation of visuo-spatial regions. The results of the haptic explorations as well as the EEG-power changes indicate a cortical dysfunction and deficits in somatosensory integration processing in anorexia nervosa patients.

Adolescent↗
PubMed1999

Why do we determine alpha-glucosidase activity in human semen during infertility work-up?

alpha-Glucosidase is a normal constituent of human semen, produced mainly in the epididymis. It is significantly correlated to sperm count. Its activity is low in cases of epididymal obstruction. We evaluated alpha-glucosidase activity in 653 semen samples of patients, who attended our department for marital infertility, with respect to associations to clinical and other seminal parameters. The normal range (mean +/- 2 SD) in samples with normal parameter values was 7.2-46.4 mU ml-1. The determination in patients with azoospermia revealed mean values of 7.7 +/- 9.5 mU ml-1 in obstructive azoospermia, and 15.8 +/- 11.5 mU ml-1 in nonobstructive azoospermia. The difference was not statistically significant in that the sensitivity of determination with respect to the presence of obstruction was only 0.66, and the specificity 0.83. A significant correlation (r = 0.34) of alpha-glucosidase activity with log sperm count was observed. The mean alpha-glucosidase activity was not significantly different in groups formed according to sperm motility, according to leucocyte count or according to semen volume. A difference between smokers and nonsmokers with comparable sperm count, as reported in the literature, did not occur. We conclude from our results that the determination of alpha-glucosidase activity does not give additional information of the fertility status exceeding that of other clinical investigations or parameters of semen analysis.

Humans↗
PubMed1999

Differential expression of SNAP-25 isoforms and SNAP-23 in the adrenal gland.

In the rat adrenal gland, we previously observed that SNAP-25 is not restricted to the plasmalemma in noradrenergic cells as it is in adrenergic cells, and hypothesized that SNAP-25 isoform expression is different in the two phenotypes. Expression of SNAP-25 isoforms and SNAP-23 was examined by immunoblotting, immunofluorescence, and RT-PCR. Amplifications of SNAP-25 mRNAs were combined with Southern hybridization, restriction enzyme analysis, and sequencing of cloned PCR products to compare SNAP-25 isoform expression in rat and bovine adrenal glands. SNAP-25 and SNAP-23 mRNA and protein are expressed in the glands; SNAP-23 is enriched in the adrenal cortex, whereas SNAP-25 is restricted to the adrenal medulla. Furthermore, high levels of SNAP-25 and low levels of SNAP-23 are observed in the PC12 cells, whereas both SNAP-25 and SNAP-23 are expressed in adrenal medullary cultures. In all extracts, the SNAP-23 mRNA corresponded to SNAP-23a. SNAP-25a is the major form expressed in rat adrenal glands (75%), as it is in PC12 cells (80%), but both SNAP-25a and SNAP-25b (40% vs. 60%) are expressed in bovine adrenal medulla in situ and in culture. In addition, an enriched population of adrenergic cells (93%) expressed a higher level of SNAP-25b (70%), suggesting that this isoform may not be restricted to fast neurotransmission.

Adrenal Glands↗
PubMed1999

Coping with infertility: distress and changes in sperm quality.

Infertility represents a serious stressor for some patients as well as a risk factor for a decrease in sperm quality. The purpose of the present study was to identify coping strategies that went along with both better emotional and physical adjustment to infertility. The sample consisted of 63 patients who contacted an andrological clinic more than one time. Prior to clinical examination, patients filled out a questionnaire referring to the way in which they coped with their wives' previous menstruation. Participants also completed a scale assessing perceived distress due to infertility. Change in sperm concentration since baseline semen analysis and the level of distress were used to evaluate patient's adjustment. The better-adjusted patients showed less prominent overall coping efforts, and a higher proportion of distancing coping strategies. An improvement in sperm quality also was associated with a low cognitive involvement in infertility. Situational uncontrollability of infertility could be a moderator of the effectiveness of coping employed by the better-adjusted patients. In addition, the coping behaviour related to better adjustment could be due to a dispositional stress resistance factor. For clinical implementation of the findings, the attitudes of a patient and the expectations of his wife have to be taken into consideration.

Adaptation, Psychological↗
PubMed1999

The intra- and inter-assay variation of the indirect mixed antiglobulin reaction test: is a quality control suitable?

The test most commonly used to detect sperm antibodies is the mixed antiglobulin reaction (MAR), standardized by the World Health Organization. The indirect MAR test detects soluble sperm antibodies in seminal plasma by using healthy donor spermatozoa as antigen. In this study we systematically investigated the influence of donor spermatozoa and the source of sperm antibodies upon the results of the indirect MAR test, and calculated the intra- and inter-assay variations. Using one individual seminal plasma and the same donor semen, results of the indirect MAR test are highly reproducible (low intra-assay variation). Two dimensions of inter-assay variation must be considered: (i) serial ejaculates of an individual donor may be used at different times; (ii) different donors may be applied to identical antibody sources. Donor spermatozoa strongly influenced the results of the indirect MAR test. Using multivariate statistical tests, highly significant main effects between the different donors (P < 0.001) and specific reciprocal effects between donor spermatozoa and seminal plasma samples (P < 0.001) were observed. The high inter-assay variation of the indirect MAR test will lead to incorrect results. There is urgent need of a reliable and reproducible test for sperm antibody detection to improve quality control of the methods.

Autoantibodies↗
PubMed1999

Pharmacokinetics and tolerability of iopromide 240 after lumbar myelography.

OBJECTIVE: To evaluate the pharmacokinetics and tolerability of iopromide 240 mg iodine/mL after intrathecal administration. METHODS: Eleven patients with an indication for lumbar myelography received 10 mL iopromide 240 in an open, prospective, single-center study. All patients were followed 72 hours after the procedure and remained in the hospital. Urine was sampled from before the myelography up to 72 hours after the procedure in stages (range, 0-6, 6-12, 12-24, 24-48, and 48-72 hours). Iodine plasma levels were determined before and 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 9 hours, 12 hours, and 24 hours after the administration of iopromide 240. Vital signs were measured at baseline, before, and 1 and 24 hours after the procedure. Physical and neurologic examinations were performed in all patients at baseline and at the end of the study period; all adverse events were recorded. The results were subject to pharmacokinetic analysis using compartment model-independent and -dependent methods. RESULTS: Ten of 11 patients had measurable iodine plasma levels. After a lag time of approximately 0.6 hours (mean value), maximum iodine concentrations of 45% of the administered dose per total plasma volume were observed after 3.8 hours. Plasma half-lives ranged from 3.0 to 60.5 hours (model-independent methods) with a mean of 14.9 hours and a standard deviation of 17.0 hours. Using curve fitting with an open one-compartment model revealed good agreement with the model-independent methods (half-life 17.3 hours). The recovery of iodine in urine in the 72-hour period was 78%+/-15% (range, 53%-94%) as a result of an undeterminable loss of urine in some patients and prolonged half-lives in two patients. Only one patient had adverse events 24 hours after myelography. CONCLUSIONS: After lumbar myelography, iopromide 240 is almost completely excreted renally within 72 hours, with a prolonged half-life as a result of the route of administration. The kinetics of iopromide 240 after intrathecal administration are characterized by a prolonged half-life. The safety of the contrast medium was confirmed.

Adult↗
PubMed1999

Cognitive-behavioral therapy for idiopathic infertile couples.

BACKGROUND: The purpose of this pilot study was to evaluate the impact of a 6-month cognitive-behavioral therapy for infertile couples. METHODS: Seventeen idiopathic infertile couples participated in a therapy program comprised of modules to behaviorally optimize the chance of conception, improve sexual functioning and satisfaction, reduce thoughts of helplessness and, if necessary, improve marital communication skills. Pre- to posttreatment changes in the therapy group were compared to changes in two control groups. RESULTS: The therapy group showed an improvement in sperm concentration, a reduction in thoughts of helplessness and a decrease in marital distress. By the end of therapy participants practiced timed intercourse more reliably and reported unchanged sexual pleasure and satisfaction during the nonfertile period of the menstrual cycle. At the 6-month follow-up, problem-focused thoughts had decreased. The live birth rate was higher in the therapy group than in epidemiological samples. CONCLUSION: Preliminary data suggest that cognitive-behavioral treatment may be an effective approach for the treatment of infertility.

Adult↗
PubMed1999

Altered sperm function or sperm antibodies are not associated with chlamydial antibodies in infertile men with leucocytospermia.

OBJECTIVE: Leucocytospermia, defined as a concentration of more than 10(6) leucocytes/ml of seminal fluid in patients without clinical symptoms due to an adnexitis, is seen in about 10% of patients in an infertility department. Infection with Chlamydia trachomatis is possibly relevant as other pathogenic bacteria were not cultured from the semen in significant numbers. SETTING: University Clinic, Department of Andrology. PATIENTS: Two hundred and seven patients attending the department for male infertility investigation. METHODS: Analysis on each semen sample included determination of leucocyte count and the MAR test for the detection of sperm antibodies. Chlamydial antibodies in semen were determined using an on-slide enzyme immunoassay. RESULTS: No differences between leucocyte counts in patients with and without chlamydial antibodies were detected. In addition, no differences in the sperm parameters or results of MAR-tests in these two groups was seen. There were no correlations between the leucocyte count and sperm parameters, including the MAR-test results. CONCLUSIONS: We conclude that antibodies to chlamydiae in semen are not associated with leucocytospermia. Leucocytospermia per se does not appear to be significant for the sperm functions and immune responses to sperm.

Antibodies, Bacterial↗
PubMed1999

Quality assessment of computer-assisted semen analysis (CASA) in the andrology laboratory.

If quality is assessed with regard to computer-assisted semen analysis (CASA), the evaluation of seminal fluid in the andrological laboratory has to be considered. Three levels of quality assessment are generally accepted: structure, process and results. Quality of structure mainly concerns the quality of laboratory assessment, in particular the skill of the staff and the equipment used. The quality of the CASA system itself is difficult to assess. Process quality concerns the quality of performing a diagnosis. When the parameter settings of the CASA system and the handling of the sample are defined, the reproducibility of the CASA values is clearly better than that of the visual estimation of motility. CASA systems are also superior to other methods regarding the documentation of laboratory values, as all the values are obtained directly online. Result quality comprises the precision, reliability and reproducibility of measurement as well as the significance of values with respect to their biological relevance. Concluding from the definitions as quoted above and from reports of the literature it may be stated that: (i) in the dimensions of structure and process quality, CASA is superior to other methods of measuring sperm motility; (ii) the evaluation of results and quality of results, however, is highly problematic; (iii) CASA systems do not appear to be superior to the visual estimation of sperm motility with respect to the fertilizing capacity of spermatozoa; (iv) the guidelines of the WHO task force form a basis for sufficient process quality; (v) further efforts should actually focus not on the improvement of investigation technology, but on the improvement in the qualification of investigators.

Humans↗
PubMed1999

Serum levels of inhibin B in men with different causes of spermatogenic failure.

Inhibin B appears to be the physiological feedback signal for FSH. Herein the determination of serum levels of inhibin B, FSH, LH and testosterone in 148 infertile patients and their association with clinical findings and seminal parameters are reported. A significant negative correlation of FSH and inhibin B (r = -0.60) was found. LH levels showed a significant inverse correlation (r = 0.37), but a weak regression (c0 = 0.01). No correlation with testosterone levels occurred. A significantly positive correlation was observed between testis volume and inhibin levels (r = 0.39) as well as between sperm count and inhibin levels (r = 0.39). To evaluate whether the secretion of inhibin B depends on the nature of damage to the Sertoli cells, inhibin levels in 23 patients with varicocele; eight after cryptorchidism, and 16 after hemiorchiectomy were compared to those of other patients without these diseases, but identical sperm count. No significant differences were found. In 20 men undergoing testicular biopsy, inhibin levels were compared to histology. Although the men with Sertoli-cell-only syndrome had significantly lower levels ((15.83 +/- 12.2) pg ml-1) than those with normal spermatogenesis ((183.8 +/- 112.3) pg ml-1), a distinction between patients with hypospermatogenesis from those with normal spermatogenesis was not possible on the basis of inhibin levels. Between these groups, the distinction was better achieved by the FSH levels (sensitivity of 85%). We conclude that inhibin B levels are a serum marker of Sertoli cell function, but the prediction of the quality of spermatogenesis is not superior to that of FSH levels.

Cryptorchidism↗
PubMed1998

Concept activation and coordination of activation procedure require two different networks.

In the present study, we used EEG-coherence analysis to assess general regional changes in neuronal activity related to semantic retrieval, testing the hypothesis that concept activation and coordination procedures are neurobiologically distinguishable. Four subjects had to decide whether or not a capital letter and a lower case letter have the identical name (e.g. Aa). This task requires two mental procedures: (i) the activation of concepts and (ii) their coordination, particularly when the interstimulus interval is shorter than the duration of concept activation. This memory retrieval of a concept appears to be subserved by two distinct networks: the left parietotemporal region for concept activation and the prefrontal region for coordination.

Adult↗
PubMed1998

Substrate and binding specificity of aspartic proteases with milk clotting properties.

The hydrolysis of whole casein and isolated casein components were investigated with the purpose of obtaining information concerning the kinetic and specifty of aspartic proteases in rennin, pepsin and 4 microbial rennet substitutes. The velocity of hydrolysis decreased rapidly within the first hour. However, the hydrolysis was not completed after 2 days. A mathematical description of the slope of hydrolysis is possible by use of exponential equations. More than 40 peptides were detected by capillary electrophoresis or PAGE. The characterization of the C- and N-terminal amino acids of peptides shows that the hydrolysis of any peptide bond depends mainly on the structure of the C-terminal side chains of the amino acids. The detection of the basic amino acids lysin and arginin in the C-terminal position of peptides is a new result, furthering the knowledge about the specificity of aspartic proteases. Differences in the reaction velocity or in the extent of hydrolysis are one of the possible explanations for the described differences in the rennet curd yield. It was concluded that the rennet enzymes are active also in the later phases of cheese ripening and are able to support the action of cheese ripening flora.

Amino Acids↗
PubMed1998

[Incidence of gynecomastia in dermatology patients].

Gynecomastia is an enlargement of the male breast. We studied a group of 115 men attending a dermatological clinic to evaluate the frequency of possible risk factors and hormonal findings. Gynecomastia was diagnosed, if a horizontal skinfold exceeded 2-3 cm, and if the diameter of the areola wa greater than 3 cm. In 32 patients (27.8%) the criteria for gynecomastia were fulfilled. The frequency increased significantly with the body mass index. 18 different medications were identified, but only two were take by more than two patients (allopurinol, coronary dilators). None of the 15 underlying diseases was associated with a significant increase or decrease in the risk of gynecomastia. Serum cortisol was the only endocrine study which was associated with an increased incidence of gynecomastia. As gynecomastia appears frequently as a phenomenon unrelated to other diseases or medications, it may be a condition per se.

Adolescent↗