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Biomedical subjects

W Hoffmann

Publications and source records attributed to W Hoffmann.

At least 235 records · Page 13Linked to original sources
PubMed1983

A novel peptide designated PYLa and its precursor as predicted from cloned mRNA of Xenopus laevis skin.

A variety of peptides closely related to mammalian hormones and neurotransmitters are secreted from amphibian skin. Using cDNA clones of mRNA isolated from skin of Xenopus laevis, we have been searching for precursors of some of these constituents. Here we present the sequences of parts of cloned mRNAs which code for precursors of a novel peptide. In the predicted polypeptides, pairs of basic residues flank a sequence of 25 amino acids terminating with glycine, the signal for the formation of a terminal amide. The predicted final product liberated from these precursors would be a peptide comprised of 24 amino acids starting with tyrosine and ending with leucine amide, which has therefore been designated PYLa. This peptide can form an amphipathic helix similar to that found in peptides with cytotoxic, bacteriostatic and/or lytic properties.

Amino Acid Sequence↗
PubMed1983

[Effect of mental stimulants on electroconvulsive shock-induced retrograde amnesia].

The effect of nootropics on the retrograde amnesia induced by electroshock was studied on a model of the active conditioned escape reaction (pole jumping). In untreated animals the daily application of electroshock for three days, immediately after the training, led to a significant retardation of the development of a conditioned escape reaction. The administration of nootropics influences the development of the retrograde amnesia to different extents, the treatment regimen (application of the drug only during the training and supplementary pretreatment before the first day of training; respectively) being of importance. The antiamnestic effect of Piracetam (100 mg/kg, intraperitoneally) which is good also without pretreatment, may still be potentiated, especially on the fourth day of treatment, by an additional administration of the drug, beginning four days before the first day of treatment. In contrast to this, meclofenoxate hydrochloride (100 mg/kg, intraperitoneally) and pyritinol (100 mg/kg, intraperitoneally) produce a marked inhibition of the development of the retrograde amnesia only after pretreatment. Without pretreatment these drugs exert a slight or no effect. The marked antiamnestic effect of methylglucaminorotate (225 mg/kg, intraperitoneally) and by an additional pretreatment. As to dihydroergotoxin (1 mg/kg; intraperitoneally), both treatment regimens were ineffective in the model used.

Amnesia, Retrograde↗
PubMed1983

[Antihypoxic effect of tisochromide (16-244) in comparison with piracetam].

The antihypoxic activity of Tisochromide (3-[4'-dimethylamino-4'-methylpentyl(2')-carbamoyl]-6,7-dimethoxy-1-thiaisochroman-1,1-dioxide), a substance of clinically antidepressant action, is studied on three hypoxia models and compared with that of the nootropic agent Piracetam: -- Tisochromide produces a dosis-dependent prolongation of the survival time of mice exposed to nitrogen hypoxia. -- The hypoxia-induced increase of lactate and pyruvate in the mouse brain is inhibited by this preparation. -- As to anoxia-induced electroencephalographic changes in the rat. Tisochromide increases the cerebral resistance against anoxia and shortens the isoelectric part of the encephalogram as well as the postanoxic phase of normalization.

Animals↗
PubMed1982

Tachyarrhythmic syncopes in children with structurally normal hearts with and without QT-prolongation in the electrocardiogram.

Forty children with presumed ventricular tachyarrhythmic syncopes in the absence of structural heart disease were studied. Twenty-nine patients, one of whom was deaf, had a prolonged QT-interval in the resting electrocardiogram (Group 1); eleven patients had a normal QT-interval (Group 2). The median QTc-interval vas 0.51 s in Group 1 and 0.40 s in Group 2. Familial occurrence suggesting autosomal dominant inheritance was found in 21 of 28 normally hearing patients in Group 1 and in 2 of 11 patients in Group 2. Syncopes were definitely stress-induced in 22 patients in Group 1 and in all 11 patients in Group 2. Of 23 patients in Group 1 in whom an electrocardiogram was obtained during physical exercise, only one showed severe ventricular dysrhythmia. In contrast, all eleven patients in Group 2 developed severe ventricular dysrhythmia with exercise. Treatment with beta-blocking medication prevented further syncopes in 15 of 19 patients with several previous attacks in Group 1 and in 3 of 5 patients of Group 2. Four of the 29 patients in Group 1 died suddenly and one more remained apallic after an attack. Of the 11 patients in Group 2, four died suddenly and one retains severe cerebral damage after resuscitation from ventricular fibrillation. We conclude that, besides the group of patients with the long QT-syndrome, there may be a distinct group of patients with a consistently normal QT-interval and severe ventricular dysrhythmia with exercise. Patients of both groups are threatened by sudden death and are improved by treatment with beta-blocking medication.

Adolescent↗
PubMed1982

[Anastomotic technique in tracheal resection. Animal experiments (author's transl)].

In 24 rabbits and 6 dogs, two subtotal tracheal transsections each were reanastomosed using Dexon , Vicryl, Prolene and Mersilene in running or interrupted suture technique. In order to avoid traumatisation of the perichondrium, sutures included the marginal cartilagenous ring and all layers of the tracheal wall. By putting every second stitch in a 8-figure, an ideal adaptation could be achieved. Half of the anastomoses were secured by additional application of fibrin tissue adhesive. Macroscopical and histological examinations were carried out 5, 10, 21 and 63 days postoperatively. Mersilene resulted in remarkable inflammatory tissue reaction - increasing from the 5th day on - leading to extensive granulomas, abscesses, ulcerations of the mucosa and erosion of the cartilage. In contrast, by using synthetic absorbable materials as well as prolene, minimal tissue reaction occurred with an even and delicate scar formation. The findings do not support the view, that an extramucosal stitch technique is essential. The additional sealing with fibrin tissue adhesive increased the safety of the anastomoses during the early postoperative period.

Animals↗
PubMed1981

Cell electrophoresis for diagnostic purposes. I. Diagnostic value of the electrophoretic mobility test (EMT) for the detection of gynaecological malignancies.

Lymphocytes from 278 gynaecological patients (100 controls and 178 patients with a malignant condition) have been investigated for their response to encephalitogenic factor, cancer basic protein, and KCl extract of adenocarcinoma of the body of the uterus as "antigens", using tanned sheep erythrocytes ETS as indicator particles in the electrophoretic mobility test (EMT). Electrophoretic mobility was measured with a Zeiss cytopherometer. The study was split into three test series producing in the cancer group 66% correct positive test results (34% false negatives) and in the control group 83% correct negative results (17% false positives). Consequently, with the instrumentation used, EMT is, at least in our hands, not sufficiently reliable for the diagnosis of cancer.

Adenocarcinoma↗
PubMed1981

Cell electrophoresis for diagnostic purposes. II. Critical evaluation of conventional cytopherometry.

Determination of the electrophoretic mobility of test cells has been widely used in an attempt to detect so-called lymphokines in a laboratory test for cancer, but operational difficulties are inherent in conventional cytopherometers. This study therefore investigates the technical and operational aspects of cell electrophoresis, using the Zeiss cytopherometer; e.g. influence of electro-osmosis, focus uncertainty, movement due to convection and other sources of error. Implications and possible improvements in the test are discussed.

Cell Movement↗
PubMed1981

Intrinsic molecules in fluid phospholipid bilayers. Fluorescence probe studies.

Fluorescence probe data using 1,6-diphenyl-1,3,5-hexatriene for various concentrations of intrinsic molecules (cholesterol, gramicidin A amd cytochrome oxidase) within fluid lipid bilayers have been examined. The polarization value increases with increasing concentration of intrinsic molecule and then approaches a limiting value. Empirical curve-fitting of the experimental data, change of polarization with concentration, shows that each system can be fitted approximately by an exponential curve. A theory has been constructed based upon the assumption that only one intrinsic molecule need be adjacent to a fluorescent probe molecule to affect its motion drastically. The change in probe motion then depends upon the probability p of all positions next to a lipid chain being free of intrinsic molecules. The value of the probability p has been calculated and it is shown that (formula: see text) depending on whether the intrinsic molecule spans the lipid bilayer or not. The approximation p = e-Mx gives a good fit to the data for all x, thereby explaining the observed phenomenological fit. The fluorescent probe data is interpreted to show that protein-protein contacts increase as the intrinsic protein concentration increases within the lipid bilayer. An apparent dichotomy between the results from the fluorescence probe and from the deuterium magnetic resonance is explained in terms of a dominant affect on the probe being its hindrance to motion by interaction with the intrinsic molecule (protein) whilst individual C2H2 groups of the chain may exhibit greater disorder.

Cholesterol↗