PubMed Health⌕ Search

Biomedical subjects

W Vach

Publications and source records attributed to W Vach.

50 records · Page 3Linked to original sources
PubMed1995

[Effect of pregnancy and labor on serotonin metabolism].

Several complications of pregnancy have been reported to be associated with alterations of serotonin (5-hydroxytryptamine; 5-HT) metabolism. Reported data regarding changes of 5-HT metabolism in pregnancy are partially contradictory. The presented study tries to describe pregnancy-associated changes in 5-HT metabolism. Urine and blood samples were taken from 20 pregnant women 4 weeks before, within 24 hours and on the 4th day following delivery. 17 non-pregnant age-matched women served as controls. 5-HT and its main metabolite 5-hydroxyindoleacetic acid (5-HIAA) were analysed. We observed a continuously increasing production and excretion of unbound 5-HT and 5-HIAA during pregnancy. Four days after delivery 5-HT production returned to baseline levels, while excretion remained elevated. 5-HIAA excretion increased in pregnancy and return to baseline levels on the day following delivery. Increased 5-HT metabolism and excretion results in a decreased 5-HT serum concentration despite increased 5-HT production during pregnancy. Our results help to understand the contradictory observations of elevated 5-HT production on the one hand and decreased 5-HT activity during pregnancy on the other.

Adult↗
PubMed1995

Pattern of carboplatin-induced emesis. The German Ondansetron Study Group.

In contrast to the broad experience concerning the therapeutic use of carboplatin, only limited data are available regarding the patterns of carboplatin-induced emesis, one of its most distressing side effects. This study reports frequency, severity and time course of carboplatin-induced vomiting and nausea refractory to 5-HT3 antagonism. A total of 216 patients receiving single-day carboplatin-based chemotherapy regimen were enrolled into an open multicenter study focusing on the safety and efficacy of ondansetron 8 mg t.d.s. Emesis on day 1 occurred in 22% and nausea in 75% of the patients; 44% of patients reported some degree of vomiting within the 5 days observation period. The risk for emesis and nausea over 2-5 days was increased in patients suffering from emesis on day 1 (relative risk 2.25 for vomiting and 2.84 for nausea, respectively). The median cumulative number of emetic episodes was 0 for all patients and 4 for the patients who did vomit at least on 1 day. Vomiting began on average 1.77 days following chemotherapy administration. The mean duration of vomiting was 2 days and 3.1 days for nausea. Carboplatin showed a monophasic prolonged pattern of emesis. The combination with cyclophosphamide led to an earlier onset and a higher frequency of vomiting. The analysis of the pattern of emesis refractory to 5-HT3 receptor blockade should help to describe the course of emesis, which is probably triggered through a 5-HT3 receptor-independent mechanisms.

Adolescent↗
PubMed1995

[The recognition of mandibular asymmetries in the panoramic tomogram. An example of the need for judging the value of a diagnostic procedure].

According to Habets et al. (1988), dental rotational panoramic radiographs can be used to diagnose vertical asymmetries between the right (R) and left (L) mandibular condyle and/or ramus. The difference in vertical height between the two sides is expressed by an asymmetry index which is calculated with the formula (R - L)/(R + L) x 100%. The aim of this paper is to investigate the accuracy of this diagnostic method with the help of the parameters sensitivity and specificity. For each of 25 fully preserved and macerated skulls with a stable occlusion. Two dental rotational panoramic radiographs were made. The values obtained for condylar and rami heights as well as for the asymmetry indices as proposed by Habets and al. (1988) were compared with the values received from the corresponding measurements on the skulls. For the determination of sensitivity and specificity, the five highest asymmetry values found on the skulls were classified as "high asymmetry present". In order to achieve an acceptable sensitivity (.8), an insufficient specificity must be accepted (for ramus height .25, condyle height .2), resulting in a very high rate of false positive diagnoses. The study emphasizes the necessity of a critical evaluation of the utility of diagnostic tests and procedures.

Diagnostic Errors↗
PubMed1994

Adjunctive intracoronary infusion of antithrombin III during percutaneous transluminal coronary angioplasty. Results of a prospective, randomized trial.

BACKGROUND: Heparin needs the plasma protein antithrombin III to function as an inhibitor of thrombin, and local antithrombin III deficiency might therefore limit the antithrombotic effectiveness of heparin during percutaneous transluminal coronary angioplasty. METHODS AND RESULTS: In the present double-blind study, 615 consecutive patients undergoing percutaneous transluminal coronary angioplasty (PTCA), of a total of 713 stenoses, were prospectively randomized to receive a bolus injection of 15,000 U heparin followed by a continuous intracoronary infusion via the guiding catheter of either 250 U heparin per minute or 250 U heparin plus 25 U antithrombin III per minute during the procedure. Four clinical variables, 19 lesion-specific characteristics, and 16 procedure-related variables were evaluated. Procedural success was assessed by quantitative angiography; procedure-related ischemic complications were analyzed during in-hospital follow-up. Procedural success rates (< 50% final diameter stenosis and no major ischemic complication) were similar, with 85% in the heparin group (n = 324 patients) and 83% in the heparin+antithrombin III group (n = 291 patients). Percent diameter stenosis after PTCA was 39 +/- 18% in the heparin group and 40 +/- 20% in the heparin+antithrombin III group (NS). There were no differences between the two groups with respect to PTCA-related acute vessel occlusion, angiographic evidence of intracoronary thrombus formation, post-procedure creatine kinase increase, Q-wave myocardial infarction, or emergency coronary artery bypass surgery. High-risk subgroup analysis revealed no beneficial effect of adjunctive intracoronary antithrombin III in any of the analyzed subgroups. In addition, although risk stratification according to the criteria of the American College of Cardiology/American Heart Association Task Force classification proved to be very useful for the entire study population, no beneficial effect of intracoronary antithrombin III infusion was observed in any of the different risk groups. CONCLUSIONS: Compared with heparin alone, adjunctive intracoronary antithrombin III therapy does not appear to have any beneficial effect on procedural outcome as well as type and frequency of acute complications during PTCA even in subgroups of patients with a high risk for thrombotic complications. Thus, a local deficiency of antithrombin III does not play a major role for the failure of heparin to abolish thrombotic complications during PTCA.

Aged↗
PubMed1994

Comparison of the emetogenic potential between cisplatin and carboplatin in combination with alkylating agents.

Platinum-based polychemotherapy is widely used in the treatment of gynecological cancer. Emesis is one of the most disturbing side-effects of platinum therapy. We performed a study to evaluate and compare the emetogenic potential and the different emesis pattern after cisplatin and carboplatin under antiemetic treatment with ondansetron. One hundred and twenty-two patients with either cisplatin-containing (n = 70) or carboplatin-containing (n = 52) first-line chemotherapy were included. Treatment with cisplatin led more frequently to emesis and patients suffered from more severe emesis than carboplatin treated patients. Delayed emesis was observed after both platinum analogues but occurred more frequently and lasted longer after cisplatin.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

[The course of pregnancy in patients with malignancies].

There is a low incidence of pregnancy associated with malignancy. We performed a retrospective analysis of patients of 16 to 35 years of age with malignancies, who had given birth to children in Freiburg 1980-1989. 170 patients were included. 118 patients became pregnant before a malignancy was diagnosed. Malignancy was diagnosed during pregnancy in 24 patients, and 28 patients became pregnant after diagnosis of and therapy for neoplasm. The frequency of preterm delivery, growth retardation and performance of Caesarean section was markedly increased only in patients with concurrent pregnancy and malignancy. 59 children were born after their mother had been treated for a malignancy. Treatment was started during pregnancy in 19 cases. 40 children were born to mothers who became pregnant after treatment. Malformations and abnormalities with respect to the development of the children were observed in similar frequency in both groups and occurred more frequently compared to the group of children, who were born before the treatment of the mother. These results were supported by an analysis of 16 siblings. We conclude, that there is a demand for national and international registries for all pregnancies associated with malignancies. Long-time observation of the children born to mothers, who had been treated for malignancy are necessary.

Adolescent↗
PubMed1993

[Effect of pregnancy on the incidence and course of malignant diseases].

Fortunately, coincidence of pregnancy associated with malignant neoplasm is rare. As reported in the literature, incidence is 1.5-10: 10,000 pregnancies. The study presented reports data on the incidence and outcome of 16-35 years old female patients suffering from malignant neoplasms. Patients, who were treated in Freiburg 1980-1989, were considered for evaluation. We analysed the impact of pregnancy on the outcome of these patients by stratifying patients for the time of diagnosis (before, during, or after a pregnancy). 247 patients were included. 118 patients developed a neoplasia after a successful pregnancy. In 24 patients, neoplasia was diagnosed during pregnancy, and 28 patients became pregnant after diagnosis and therapy for a malignancy. Further 77 patients without pregnancy, but in whom neoplasia diagnosed at the age of 16-35 years were included. Cancer of the cervix uteri, breast cancer, ovarian cancer, and malignant lymphomas were the most frequent neoplasias diagnosed in young women. In an analysis stratified for stage of disease, we found no significant difference between 3- and 5-years survival of patients with pregnancies before, during, or after diagnosis and treatment of neoplasia. Due to the inhomogeneity of the subgroups analysed, the question, whether pregnancy has any impact on the outcome of neoplasm could not be conclusively answered. The necessity for the establishment of national and international registries collecting sufficient data about incidence and outcome of patients with pregnancies associated with malignant neoplasms is emphasised.

Adolescent↗
PubMed1992

Course, patterns, and risk-factors for chemotherapy-induced emesis in cisplatin-pretreated patients: a study with ondansetron.

Vomiting and nausea are the most distressing side-effects of cancer chemotherapy. With standard antiemetic regimens (e.g. metoclopramide based combinations) sufficient antiemetic control is achieved in 50-70% of cisplatin treated patients. Ondansetron, a selective 5-HT3-receptor antagonist has shown efficacy in cisplatin-induced emesis. In the present study, we evaluated the safety and efficacy of ondansetron in cisplatin pretreated patients who had suffered from severe emesis in spite of antiemetic prophylaxis. Complete antiemetic control was reached in 43.5% on the day of treatment and in 27.2% of the patients regarding a worst day analysis. 25% of the patients suffered from severe cisplatin-induced emesis (greater than 5 emetic episodes per 24 h). We try to characterise risk-factors for cisplatin-induced emesis by performing a multivariate analysis. Sex, cisplatin dose, and combination therapy with cisplatin plus anthracyclines seem to be independent risk-factors for vomiting on day 1 and on worst day. Delayed emesis occurred less often when sufficient antiemetic protection from acute vomiting had been obtained. Female sex, cisplatin dose and recurrent disease seem to influence the probability for occurrence of delayed vomiting.

Adult↗
PubMed1992

Movement disorders in astrocytomas of the basal ganglia and the thalamus.

In a series of 225 patients with astrocytomas (grades I-IV) of the basal ganglia and the thalamus, 20 had a movement disorder. In all patients the histological diagnosis was verified by stereotactic biopsy. Tremor was observed in twelve patients, dystonia in eight, chorea in three, and chorea/ballismus and myoclonus in one. The tumour involved the thalamus in 16 patients. Corticospinal tract dysfunction was evident in 70% of the patients with movement disorders and in 73% of those without. Demographic, clinical, histological and neuroradiological data of the patients with a movement disorder were compared with the data of patients without. CT data yielded no differences with respect to the involvement of anatomical structures. Movement disorders were significantly associated with low-grade astrocytomas.

Adolescent↗
PubMed1992

[Pilot study of dose dependence in glucuronidation of morphine to morphine-3- and morphine-5-glucuronide].

In the capacity of an initial study both, the half-lives of morphine and its metabolites morphine-3-glucuronide and morphine-6-glucuronide as well as the ratio of concentrations in the development of time using two different dosages were determined and shown by comparison. A bolus of 10 mg (10 micrograms) tritium-marked morphine was administered intravenously. Subsequently the half-lives of morphine, morphine-3-glucuronide and morphine-6-glucuronide in serum, saliva and urine were determined. To achieve this, morphine and its glucuronides were separated via HPLC and then quantified by measuring the radioactivity. In addition to the short half-lives of morphine and morphine-glucuronides long half-lives were found in the range of 12.6 to 20 hours in serum and urine. There was no positive evidence for glucuronides in saliva. In urine the morphine/glucuronide ratio showed a linear resp. exponential development dependent of dose.

Adult↗
PubMed1991

Biased estimation of the odds ratio in case-control studies due to the use of ad hoc methods of correcting for missing values for confounding variables.

The effects of missing values for a confounding variable are investigated in the setting of case-control studies in which, for simplicity, the effect of one binary risk factor and one categoric confounding variable on disease risk is under investigation. Some ad hoc techniques with which to deal with missing values are examined under different assumptions about the missing-data mechanism. Examples are given to illustrate that the magnitude of the bias that is introduced by applying an inadequate procedure can be large under circumstances that occur frequently in empiric research. This is true even for so-called complete case analysis, i.e., when only data on subjects with complete information are used. Appropriate bias corrections are derived. Making use of data on those subjects who are neglected in complete case analysis by creating an additional category always results in biased estimation. An alternative is to allocate these subjects to the cells of the contingency table in an appropriate manner. This approach yields consistent estimates if the data are missing at random. Choosing an appropriate method for dealing with missing values always requires some knowledge of why the data are missing. This suggests that investigators should carry out validation studies to understand whether the missing values occur randomly across the study population or occur more frequently in specific subgroups.

Bias↗
PubMed1991

[Elimination half life of the opiate etorphine].

In the capacity of an initial study both, the pharmacocinetics as well as the metabolism of etorphine were investigated. In a self-trial a bolus of 8 micrograms tritium-marked etorphine as administered intravenously and subsequently the half-lives in serum and urine were determined. To achieve this, etorphine and etorphineclucuronide were separated via HPLC and then quantified by measuring the radioactivity. The development of the concentrations was devided into 3 phases. Within the first phase half-lives of etorphine and etorphineglucuronide were found in the range of 0.3-1 hour in serum and, likewise, in urine. During the second phase the estimated half-life of etorphineglucuronide was 160-260 hours in serum as well as in urine. Within the last phase half-lives in urine were 47 hours for etorphine and 41 hours for etorphineglucuronide while the calculation of the half-lives in serum was not sufficiently feasible.

Adult↗
PubMedDate not supplied

Some issues in estimating the effect of prognostic factors from incomplete covariate data.

In evaluating prognostic factors by means of regression models, missing values in the covariate data are a frequent complication. There exist statistical tools to analyse such incomplete data in an efficient manner, and in this paper we make use of the traditional maximum likelihood principle. As well as an analysis including the incompletely measured covariates, such tools also allow further strategies of data analysis. For example, we can use surrogate variables to improve the prediction of missing values or we can try to investigate a questionable "missing at random' assumption. We discuss these techniques using the example of a clinical study where one important covariate is missing for about half the subjects. Additionally we consider two further issues: evaluation of differences between estimates from a complete case analysis and analyses using all subjects and assessment of the predictive value of missing values.

Data Interpretation, Statistical↗