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Biomedical subjects

D Schuster

Publications and source records attributed to D Schuster.

At least 37 records · Page 2Linked to original sources
PubMed1994

Case report: defective beta and alpha cell regulation in patients with hyperinsulinemia and acanthosis nigricans.

Beta cell hypersecretion is associated with the syndrome of hyperandrogenism, insulin resistance, and acanthosis nigricans. It is unknown whether concomitant alpha cell secretory dysfunction occurs in patients with this syndrome. The authors evaluated the gastroenteropancreatic hormones in four family members with varying degrees of the hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome. Gastroenteropancreatic hormones were measured during oral glucose tolerance test with and without subcutaneous octreotide injection. The study revealed that the administration of subcutaneous octreotide resulted in suppression of beta cell function (insulin and c-peptide) but had no effect or a delayed effect on alpha cell secretion (glucagon). Furthermore, the severity of glucagon abnormalities paralleled that of beta cell hypersecretion and the clinical and phenotypic manifestations of acanthosis nigricans in our four patients. We speculate that this alpha cell aberration could potentially be involved in the altered glucose homeostasis and perhaps the skin manifestations of this syndrome. Therefore, glucagon levels should be evaluated in the hormonal studies in patients with hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome.

Acanthosis Nigricans↗
PubMed1991

Determination of pindolol in human serum by HPLC.

A method for determining pindolol from human serum by high-performance liquid chromatography (HPLC) is presented. Pindolol is extracted into methylene chloride from 1 mL of alkalinized serum with a recovery of 87%. The organic layer is evaporated and the residue is reconstituted in mobile phase for injection into the column. Samples are eluted from a 5-micron C18 column (250 x 4.6 mm) with acetonitrile-water containing 0.1% triethylamine, pH adjusted to 3.5 with phosphoric acid (20:80 v/v). Samples as low as 2 ng/mL have been detected.

Acetonitriles↗
PubMed1990

[Combination of recombinant interferon alpha-2A and vinblastine in advanced renal cell cancer].

Experimental results suggest synergistic activity of interferon with different cytotoxic agents, including vinblastine. Both interferon and vinblastine have shown synergistic activity against renal cell carcinoma in the human stem cell assay. In this multicenter phase II study, patients with documented advanced renal cell carcinoma were treated with interferon alpha-2a at a dose of 18 x 10(6) IU i.m. 3 days per week and vinblastine 0.1 mg/kg body weight i.v. every 3 weeks. Combination therapy was given for 6 months except patients with progressive disease. We observed 6/34 (17.6%) partial remissions and 16/34 (47%) no changes. Five out of six responses were seen in pulmonary metastases with a median response duration of 10 months and a median survival for the responders of 17 months. A dose reduction because of interferon toxicity was necessary in 60% of the treated patients. The main side effects were fever and influenza-like symptoms of different intensity in 70% of the patients, which decreased during the treatment periods. This trial demonstrates modest but definite antitumor activity of the combination of interferon alpha-2a/vinblastine. In comparison with single agent therapy we did not observe improved remission rates for the combination treatment.

Adult↗
PubMed1990

[AIDS tumors].

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Phase I-II trial of doxifluridine (5'DFUR) administered as long-term continuous infusion using a portable infusion pump for advanced colorectal cancer.

Doxifluridine, a new fluoropyrimidine analog, was administered to 21 patients with advanced colorectal carcinoma. The starting dose was 1.0 g/m2 given over 24 h for 90 consecutive days as a continuous infusion. Due to severe skin reactions (hand-foot syndrome), the dose was reduced stepwise to 0.75 g/m2/day. Twenty patients were evaluable for efficacy, one had an early non-toxic death. Seven out of 20 (35%) showed a partial response; disease stabilization was observed in 10 patients (50%) and three showed progressive disease after 3 months of treatment. All 17 patients who achieved a partial response or a stabilization of disease were treated until progressive disease was documented and some had therapy up to 46 weeks. Toxicity was minimal and mainly defined as hand-foot syndrome which occurred in 50% of the patients of whom three experienced severe reaction. There was no myelosuppression, renal or liver dysfunction, no cardiac alterations and only one patient experienced severe dizziness. Doxifluridine is active in advanced colorectal carcinoma when the drug is given as a continuous infusion for 90 consecutive days at a daily dose of 0.75 g/m2.

Adenocarcinoma↗
PubMed1989

Sequential high dose methotrexate, 5-fluorouracil and folinic acid does not improve response rates in advanced colorectal cancer.

27 patients with advanced colorectal cancer were treated in a phase-II trial with high dose sequential methotrexate (MTX), 5-fluorouracil (5-FU), and folinic acid (FA). Following a 4 h infusion of 800 mg/m2 MTX and a 4 h interval, 1,500 mg/m2 5-FU and 200 mg/m2 FA were given as a 24 h infusion. Out of 23 evaluable patients we observed one partial remission and 9 disease stabilizations. Median survival time of all patients was 10.4 months. Overall toxicity was low. In comparison to a previous trial we did not observe better treatment results by adding high dose FA to a sequential MTX/5-FU schedule.

Adult↗
PubMed1988

[Detection of HIV-1 antigen--determination using 3 different test systems].

51 human sera containing antibodies to human immunodeficiency virus 1 (= HIV-1) were examined for HIV-1-antigen by three different enzyme immunoassay procedures (= EIA) of Abbott, Organon and Dupont. Sensibilities, handling as well as the correlation with the clinical stages of HIV-infection were compared. The EIA's diagnosed in accordance 6 sera which contained HIV-1-antigen and 42 sera to be HIV-1-antigen negative. 3 sera showed differences: according to the EIA of Organon none of these sera contained HIV-1-antigen, the EIA of Abbott (but not of Dupont) analysed HIV-1-antigen in one of these sera, in the other two sera only the EIA of Dupont showed HIV-1-Antigen. It is concluded that the differences in these 3 serum samples may originate not only in the different types of EIA used (indirect/direct procedure) but also in the different capture antibodies provided (antibodies against p-24 antigen or polyvalent antibodies).

Acquired Immunodeficiency Syndrome↗
PubMed1988

False-positive DNA probe test for Legionella species associated with a cluster of respiratory illnesses.

Between 11 November 1986 and 28 February 1987, legionellosis was diagnosed in 23 patients at one hospital with a recently marketed Legionella-specific DNA probe for respiratory secretions. Only 10 of the 23 probe-positive patients showed findings typical of Legionella pneumonia, including a temperature of greater than or equal to 100.5 degrees F (approximately 38.1 degrees C) and radiographic evidence of pneumonia. No differences were found in the results of laboratory studies, demographic features, or underlying risk factors for these 10 probe-positive patients when compared with the 13 probe-positive patients with nonpneumonic illnesses. A case-control study comparing probe-positive and -negative patients failed to identify any different features of disease or epidemiologic characteristics. Probes of repeat specimens of sputum were still positive 2 to 13 weeks after the initial test in 5 (50%) of the 10 probe-positive patients. The clinical features in most patients were atypical for legionellosis, and the diagnosis could not be confirmed by traditional laboratory tests performed on duplicate specimens processed at the Centers for Disease Control. This report emphasizes the need for clinical microbiology laboratories to confirm test results from new procedures by accepted diagnostic methods.

Adult↗
PubMed1986

[Quality of life of cancer patients under chemo- and radiotherapy. Prospective study of patients with gastrointestinal and bronchial cancers].

In a prospective study, 156 patients with advanced lung and gastrointestinal carcinomas, receiving palliative chemotherapy or radiotherapy, were examined for changes in their quality of life during therapy. A questionnaire (68 questions), a linear analogue scale, and the Karnofsky performance scale were used three times in the course of therapy. The most important result seen during the evaluation of the questionnaire was the improvement in the psychical state in patients with tumor remission, even with increasing side-effects. In patients with progressive disease, a deteriorated psychosocial state and an increased burden due to the toxic side effects were observed. These results were also confirmed in progressive patients by the linear analogue scale. The Karnofsky performance scale showed a high correlation for the judgement of disease-related contents and the activity of the patient. In this study the relationship of treatment results and well-being is shown. It would seem important to include methods for the measurement of quality of life for the evaluation of oncological therapies.

Carcinoma, Bronchogenic↗
PubMed1986

[Diagnosis and treatment of cardiac rhabdomyomas].

A diagnosis of primary cardiac tumors was achieved by two-dimensional echocardiography in 3 patients. Two of them were female neonates, born of the 29th and 40th gestational week who had shown intrauterine arrhythmias. Subsequently, we were able to diagnose tuberous sclerosis in both. The third child, a 121/2 year old boy, with already diagnosed tuberous sclerosis, presented an electrocardiographical preexcitation syndrome. Because of the multiplicity of the tumors and the association with tuberous sclerosis we presumed that the tumors were rhabdomyomas. As it is known that rhabdomyomas show no, or only a minimal postnatal growth, we decided neither to perform a heart catheterization nor to treat them surgically unless the children show hemodynamical deterioration, although the tumors were huge in both neonates. The subsequent 14 months showed a clear regression in the size of the tumors. One of the neonates was successfully treated with amiodarone because of ventricular tachycardia. The second neonate didn't require any treatment. We conclude that: Surgical management is only necessary in patients presenting with cardiac insufficiency and/or arrhythmias that are resistant to conventional medical treatment. Primary cardiac tumors should be looked for in patients presenting with arrhythmias, even when occurring already during intrauterine life. Diagnostic measures in order to diagnose tuberous sclerosis in patients with cardiac tumors are necessary and vice versa.

Adolescent↗
PubMed1985

[Novel quantitative assessment of the tremorogenic effects of the beta 2-mimetics clenbuterol and salbutamol after oral administration].

A pharmacodynamic study was run in 12 healthy volunteers (4 male, 8 female, mean age 33.3 years, mean body-weight 60.8 kg) to demonstrate a dose- and time-effectiveness dependency for a beta 2-mimetic drug (clenbuterol, Spiropent) versus salbutamol and placebo as reference. A newly developed 3-dimensional tremormeter was introduced in this randomised double-blind/6-way/cross-over study. The shape of the induced tremor effects (in amplitude) as well as the pulse frequency reflected highly significant dose relationships. Drug effects started 30 min after intake and lasted longer than 600 min. 10 micrograms of clenbuterol revealed no significant differences when compared to placebo, whereas the 20 micrograms dosage as usually administered in clinical routine demonstrated significant--but only slight--differences to placebo-baseline. All other dosages and the reference (salbutamol, 8 mg) could be discriminated distinctly against placebo.

Administration, Oral↗
PubMed1980

Optimal and adaptive control in canine postural regulation.

For analytic purposes, dogs trained to stand quietly on an oscillating platform can be likened to a fixed-length inverted pendulum with a point mass. Describing function analysis permitted derivation of torque and error values as functions of phase and gain relative to platform movement. A phase criterion was determined for minimization of either control torque at a given error amplitude or error at a given control torque amplitude. Describing functions for dogs with and without vision approached optimal phase. Stretch reflex control involving proportional-plus-rate feedback is not sufficient to account for the approach to optimal phase. Blindfolded labyrinthectomized dogs did not exhibit optimal behavior and the phase constraint for stretch reflex control was satisfied at most frequencies. The observed behavior is best accounted for by a model involving both otolith and visual feedforward (pursuit-precognitive) control processes. Reductions in phase lag by blindfolded dogs during the first few cycles of platform motion provide evidence of adaptive control.

Animals↗