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Biomedical subjects

W Schumacher

Publications and source records attributed to W Schumacher.

At least 19 recordsLinked to original sources
PubMed1990

D-19466, a new cyclobutane-platinum complex with antitumor activity.

D-19466, a new platinum complex, was characterized. It showed no nephrotoxic side-effects as determined by the measurement of blood urea. It was cytotoxic in vitro for tumor cells in concentrations comparable to or lower than cytotoxic concentrations of cisplatin. It had excellent anticancer activity in vivo against a number of murine experimental tumors, including a cisplatin-resistant P388 line. Clinical evaluation of this compound has therefore been initiated.

Animals↗
PubMed1988

Characterization of the antitumor activity of hexadecylphosphocholine (D 18506).

Hexadecylphosphocholine (HPC) differs from ether lipids with known antitumor activity by its lack of the glycerol part. In the experiments described here HPC revealed outstanding antitumor activity in dimethylbenzanthracene (DMBA)-induced rat mammary tumors. A dose-response relationship was seen after daily oral treatment with complete suppression of tumor growth at doses of 46.4 mg/kg/day. There was no schedule dependence and the therapeutic efficacy was independent of the tumor weight at the initiation of therapy. Another autochthonous tumor, the benzo[a]pyrene-induced sarcoma of the rat did not respond to HPC treatment, indicating a highly selective spectrum of activity of the test compound. In comparison to an optimal single dose of cyclophosphamide, a single high dose of HPC was considerably more active against the DMBA tumor. At therapeutic dose levels no major toxicity of HPC was observed. Bone marrow suppression was not encountered, on the contrary, at high doses leukocytosis became apparent. The available pharmacological and toxicological data suggest that HPC may be useful in the treatment of human cancer.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

New technique for treating occlusive and stenosing tumours of the trachea and main bronchi: endobronchial irradiation by high dose iridium-192 combined with laser canalisation.

A new technique is described for treating patients with inoperable malignant tumours causing occlusion or stenosis of the trachea or main bronchi. High dose iridium-192 (20 Ci) was introduced by an afterloading device under computer control via a 4 mm delivery tube into the tumour mass. In 29 of the 56 patients the tumour mass was canalised by a neodymium-YAG laser immediately before the afterloading delivery tube was introduced. In 44 (79%) of the patients, there was impressive relief of dyspnoea, accompanied by tumour regression observed at endoscopy and also by highly significant improvement in ventilatory function values, lung perfusion scans, and levels of arterial oxygen tension. In the other 12 patients (21%) there was no detectable improvement. The findings suggest that this recently developed combination treatment is of value in patients with advanced tumours of the trachea and main bronchi in whom there is no possibility of further treatment by external irradiation or repeated laser coagulation.

Aged↗
PubMed1986

[New methods in the radiotherapy of bronchial carcinoma. Endobronchial small-field irradiation using the iridium-129 high-dose afterloading technic in combination with the neodymium-YAG laser].

106 patients with inoperable malignant tumours constricting the central bronchial tree underwent endobronchial small-field radiotherapy with iridium-192 at high dose between June 1983 and September 1985. Treatment was performed using the computer-guided after-loading technique and a flexible bronchoscope under local anaesthesia. In complete occlusion of a bronchus by the tumour, a neodymium YAG-laser was applied (57 patients) to allow insertion of the after-loading probe. Endoscopy showed tumour regression in 75% of the patients, accompanied by clinical improvement. Pulmonary function tests, arterial blood gas analyses and pulmonary perfusion scans yielded a highly significant improvement of data after treatment. The procedure also proved effective upon exhaustion of external radiation. Apart from its positive palliation, endobronchial small-field radiotherapy using high doses of iridium-192 also has a curative effect, thus opening up a new approach to the therapy of advanced bronchial carcinoma.

Aged↗
PubMed1986

Design of metallocenic drugs.

Studies on structure-activity relationships of organometallic anticancer drugs are reviewed. Three methods for the development of new structures are described. Drug targeting: platinum complexes with oestrophilic ligands were synthesized, and the endocrine and cytostatic effects are discussed. Quantitative structure-activity relationship determination is presented as a rational method for the design of active compounds. The molecular modelling technique is used for the analysis of molecular properties.

Animals↗
PubMed1986

[Psychometric studies of cerebral performance before and following extra-intracranial bypass operations].

34 patients suffering from cerebro-vascular occlusive disease and treated by an extra-intracranial anastomosis (EIAB) were examined by 5 different psychological tests (Test d 2, Benton Test, Revision Test, Subtest "ZN" of the Hawie, K-L-T) before and after the operation. The results showed a significant improvement of intellectual functioning in most cases. In a addition, disturbances of drive and activity and symptoms of depression were all diminished.

Attention↗
PubMed1985

[A new possibility in treating stenosing tumors of the upper gastrointestinal tract].

A new method for treating inoperable patients with stenosing malignant tumors of the upper gastrointestinal tract consists in the combination of laser beam followed by direct internal radiation of the tumor using the afterload technique. It brings rapid improvement of dysphagia and resumption of oral feeding. Improvement in quality of life such as this has been achieved in 21 of 24 patients without any signs of complication due to therapy.

Ambulatory Care↗
PubMed1985

[New possibilities in radiotherapy of endobronchial tumors using the afterloading method in combination with laser technics].

New possibilities for radiotherapy of bronchial carcinomas are provided by the combined application of the recently introduced afterloading method used hitherto in the treatment of stenosing processes of bronchial carcinomas and the neodyme-YAG laser which opens the stenosis in such a manner that the afterloading probe can be inserted. This new method allows to perform without complications or disadvantages further combined therapies such as percutaneous irradiation (telecobalt, linear accelerator or betatron). An irradiation scheme leading to a decisive tumor regression can be established due to the fast reventilation of the lung obtained by both methods. Surprisingly, three patients could be submitted despite the small-field radiotherapy to rather important lung operations such as lobectomy and pneumonectomy which were performed without complications or disadvantages. The patients were not operable without laser and afterloading therapy. This method was applied several times in the treatment of other diseases such as oesophageal cancer and stenosing cancer of the antrum. In these cases, a normal ingestion due to tumor regression was obtained rapidly.

Brachytherapy↗
PubMed1984

Biological maturation and beta-adrenergic effectors: development of beta-adrenergic receptors in rabbit heart.

The beta-adrenergic receptor, transduction processes and catalytic activity of the adenylate cyclase enzyme complex have been investigated in rabbit heart at different stages of biological maturation. The binding of [3H]-dihydroalprenolol to a washed membrane preparation isolated from rabbit ventricular muscle was used to characterize beta-adrenergic receptors. Significant age-related differences were noted in beta-receptor affinity (Kd) and density (RD) of neonatal and adult animals; the adult Kd was 3.7-fold greater and the RD 2-fold higher than the neonates. No significant differences in these parameters were detected among the 27-day old fetus and the 1- and 7-day old neonates. Age-dependent differences in agonist isoproterenol affinity for the receptor were not observed in contrast to the significant changes in antagonist (DHA) affinity. Age-related changes in receptor affinity were also quantitated by determining the inhibitory potency of alprenolol on isoproterenol stimulated adenylate cyclase enzyme activity. A decreased affinity of the beta-adrenergic receptor for alprenolol in the adult heart was indicated by a 3.7-fold greater Ki for the adult than the 1-day old neonate. Ontogenic variations in the coupling efficiency between the receptor and catalytic components of the adenylate cyclase complex were also evaluated. The Kd of the beta-adrenergic receptor for isoproterenol and the EC50 for adenylate cyclase stimulation were determined under similar conditions. The corresponding coupling index (Kd/EC50) was found to be 2.4-fold greater in the 1-day old neonate than adult, suggesting that for a given percentage increase in adenylate cyclase activity, a lower percentage of beta-adrenergic receptor sites need be occupied in the neonate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1983

The alpha adrenergic response of Down's syndrome platelets.

The alpha adrenergic responsiveness and pharmacological characteristics of alpha adrenergic receptors were examined using platelets from normal diploid and Down's syndrome (trisomy 21) individuals. Lower than normal doses of epinephrine were required to aggregate Down's syndrome platelets and promote ATP secretion. The concentrations of other platelet aggregating agents (ADP or thrombin) did not distinguish normal from Down's syndrome. Analysis of the alpha adrenergic receptor density and ligand affinity using the radioligand dihydroergocryptine indicated that the Down's syndrome platelets were not significantly different from normal. Likewise, the biochemical characteristics of the adenylate cyclase enzyme, e.g., its sensitivity to stimulation by prostaglandin E1 or inhibition by epinephrine, were not different when comparing Down's syndrome with normal platelet membranes. These data suggest that the enhanced epinephrine sensitivity of Down's syndrome platelets is independent of any change in the alpha adrenergic receptor or the adenylate cyclase enzyme complex.

Adenosine Triphosphate↗