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Biomedical subjects

K Richter

Publications and source records attributed to K Richter.

At least 505 records · Page 28Linked to original sources
PubMedDate not supplied

Dose dependent tiracizine disposition in healthy volunteers: serum and urine kinetics and dose related ECG-changes.

The pharmacokinetics of tiracizine, a new class I antiarrhythmic agent, and 3 of its metabolites were assessed in serum and urine of 8 healthy extensive metabolisers after single oral administration of 50, 100, and 200 mg tiracizine hydrochloride. Additionally, tiracizine induced ECG-changes were compared between the different doses. With increasing doses enhancement of AUC and Cmax of tiracizine and its metabolites revealed a slight deviation from linearity indicated by exceeding the upper limits of the 95% nonparametric confidence interval set by 0.8-1.2 for the ratio (dose corrected parameters after the 100 and 200 mg dose, respectively)/(parameters after 50 mg). The increase of the dose corrected parameters after the 200 mg dose was about 1.3-fold compared with the 50 mg parameters for the parent compound as well as its metabolites. The significant decrease of the renal clearance of all 4 substances with increasing doses indicates that saturable tubular secretion mainly accounts for non-linearity. Due to the occurrence of non-linear (tubular secretion) as well as linear (glomerular filtration, hepatic metabolism) elimination in parallel, however, it is concluded that saturable tubular secretion is of minor importance at higher doses and should not be overestimated. However, there was some evidence for saturable hepatic tiracizine metabolism in 4 of the 8 participants. Therefore, a fall of apparent intrinsic clearance has also to be taken into consideration, especially at higher doses. PQ- and QRS-intervals were prolonged in a dose dependent manner and culminated at 1 h after drug intake. QTc-time, however, remained unchanged. A log-linear relationship between serum concentrations of the parent compound and PQ- as well as QRS-time is suspected for serum levels about 80 ng/ml, but has to be confirmed by individual pharmacokinetic-pharmacodynamic modelling. PQ- and QRS-intervals might be suitable for tiracizine therapeutic monitoring.

Adult↗
PubMedDate not supplied

[Characteristics of a target population for preventing house-dust mite allergy in toddlers].

AIM: To evaluate a recruitment strategy to identify high risk toddlers for a programme of prevention of allergy. For screening, parents were asked to participate in our study by information form and screening questionnaire on the occasion of routine check-up visits of toddlers scheduled between 20 and 48 months of age in four paediatric practices. As a next step, readiness of parents for implementation of preventive measures was confirmed. METHOD: Inclusion criteria were age between 20 and 48 months and a positive atopic family history (evaluated by 5 questions regarding asthma, allergic rhino-conjunctivitis and atopic dermatitis) of parents or siblings. This was confirmed by sensitization to an environmental allergen (skin prick test (SPT)) in at least one parent. If these inclusion criteria were fulfilled, the toddlers were randomly allocated to the intervention and control group of the prevention programme. RESULTS: 111 of 175 screening questionnaires (63.4 %) were returned. In 76.6 % (n = 85) of these 111 questionnaires a positive atopic family history (mother, father, sibling) was noted. All inclusion criteria were fulfilled by only 43 toddlers (age: median 33.6 months, 5-95 % quantile: 21.6-48 months). Based on the positive screening questionnaire, history of atopy was confirmed by positive SPT in 70.0 % of fathers and 77.8 % of mothers. Despite a negative screening questionnaire, history of atopy was detected by a positive SPT in 11.1 % of mothers and 47.4 % of fathers. Detection of specific IgE against house-dust mite in 9 of 18 serum samples revealed the risk for allergy of the toddlers. A re-evaluation after three months showed that all the elements of the prevention programme as well as the recommendations for the control group had been almost completely accepted by all the families concerned practically without any reservations. CONCLUSION: The recruitment of toddlers with high risk for developing allergy turned out well and could be validated. The prevention programme was readily accepted by the families and thus can be used for a larger study.

Antigens, Dermatophagoides↗
PubMedDate not supplied

[Ductus aneurysm as a rare cause of inspiratory stridor in the newborn infant].

A paralysis of the left vocal cord was seen by laryngoscopy in a 3-days-old boy with inspiratory stridor. A ductus aneurysm was established by angiocardiography, which was believed to be the cause of the vocal cord paralysis. Within 8 days after the angiocardiography the aneurysm became smaller and the stridor disappeared. Twelfth months later the control-angiocardiography showed the total obliteration of the ductal aneurysm.

Aneurysm↗
PubMedDate not supplied

[Clinical relevance of the tracheal bronchus].

We report about 6 infants with serious respiratory disease who revealed a tracheal bronchus on bronchoscopic or bronchographic examination. In two of these children this finding seemed to be the main problem; it could be cured by surgical or conservative therapy. The course of the further 4 children's disease was determined by additional serious malformations (Oesophageal atresia, congenital heart disease, anomalies of the pulmonary arteries). In these cases, the tracheal bronchus did not influence the clinical course significantly.

Abnormalities, Multiple↗
PubMedDate not supplied

[Diagnosis of bilateral renal vein thrombosis in infancy by pulsed Doppler sonography of the renal vessels].

In a premature infant bilateral renal venous thrombosis and associated thrombosis of the inferior vena cava were diagnosed at the age of 6 weeks, using a 2-dimensional ultrasound sector scanner with integrated pulsed doppler ultrasound of the renal vessels. In contrast to 30 healthy children, who showed continuous forward flow in the renal arteries throughout systole and diastole, diastolic flow was decreased or even retrograde in renal venous thrombosis (RVT) according to the severity of thrombosis. Doppler recordings in renal veins normally showed continuous retrograde flow patterns, whereas in RVT venous flow was decreased or absent. Pulsed doppler ultrasound is a useful and noninvasive method for recording renal flow patterns, especially in renovascular disease.

Humans↗
PubMedDate not supplied

X chromosomal and autosomal loss of heterozygosity and microsatellite instability in human cervical carcinoma.

The study analyzes tumor material and normal tissue from 27 patients with pure squamous cell carcinoma of the uterine cervix for loss of heterozygosity (LOH) and microsatellite instability (MSI) on 14 autosomal and 11 X chromosomal loci. Overall, 4-40% of the informative cases showed LOH at autosomal regions with the highest frequency at 3p (21-40%) and a marked frequency at 2q35-q37.1 (12.5%) and 17p13.3 (10%), representing regions with putative tumor suppressor gene (TSG) function. The frequency of X chromosomal LOH ranged from 4% to 20%, with a maximum at Xq28 (20%) and Xq11.2-q12 (17%), again indicating alterations in TSG. A 12% LOH was seen at Xq21.33-q22.3, a region encoding a protein with a regulatory function in the cell cycle via cyclin-dependent kinases. MSI was detected in autosomal regions in up to 7% in regions linked to the X chromosome in up to 11%, probably indicating alterations of mismatch repair mechanisms. Our results and those obtained from the literature suggest that autosomal LOH and MSI in carcinomas of the cervix uteri are predominantly found at regions with putative TSG function. Beside TSG alterations, X chromosomal LOH is probably more strongly connected to disturbances in cell cycle regulation.

Carcinoma↗
PubMedDate not supplied

Multiple classification and receiver operating characteristic (ROC) analysis.

The receiver operating characteristic (ROC) curve was applied to observer performances in a multiple-alternative decision task. It was shown that the probability of correct classification, a performance criterion often maximized in multiple-classification procedures, corresponds to the area under an appropriately constructed ROC curve. Degrees of confidence in the observer's judgment of 0, 1, ..., 10 were used for both classification and ROC rating. To demonstrate the validity of the method, 1,190 photofluorograms were examined by experienced staff radiologists to identify four cardiovascular conditions distinguishable on the basis of images of structural elements of the contours of the heart and great vessels. The classification matrices for three radiologists who achieved high, medium, and low performance ratings in this experiment are reported. The ROC curves are symmetric, with their points located around the off-diagonal. Differences between the overall probability of correct classification and the ROC curve index calculated from the same evaluator's data were very small, 0.004 to 0.011.

Cardiovascular Diseases↗
PubMedDate not supplied

Metabolic transformation of the brassinosteroid 24-epi-castasterone by the cockroach Periplaneta americana.

After feeding of 24-epi-castasterone to the cockroach Periplaneta americana an organ-specific epimerization of the brassinosteroid to 2,24-diepi-castasterone could be detected in female insects. The metabolite being observed only in the ovaries and not in the testes of the insect was identified by GC/MS in comparison with a synthesized authentic sample. Contrary, 24-epi-brassinolide is not metabolized in the sexual organs of Periplaneta americana. This is the first evidence of a metabolic transformation of a brassinosteroid in insects.

Animals↗