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Biomedical subjects

G Schmidt

Publications and source records attributed to G Schmidt.

At least 325 records · Page 18Linked to original sources
PubMed1987

Polymer support synthesis. XII. Derivatization with the 4-decyloxytrityl group as an aid in the affinity chromatography of oligo- and polynucleotides.

In a continuation of previous studies on trityl groups substituted with long alkyl chains as affinity-protecting groups for oligonucleotides, the use of the (4-decyloxyphenyl)diphenylmethyl (DTr) group as an aid in the separation of solid-phase products has been investigated. This substituent, which can be introduced and removed from the 5'-position in a similar manner to the di-p-anisylphenylmethyl group, helps in the purification of deoxypolynucleotides with up to 140 bases. Their retention time was shown to depend not only on the length of the nucleotide chain and alkyl substituent, but also on the elution gradient rate. In oligoribonucleotide synthesis, the DTr group allows the purification of partially protected sequences, which are more stable to enzymatic degradation and, therefore, more suitable for handling and storage.

Chromatography, Affinity↗
PubMed1987

[Clozapine-induced cholestatic liver lesions. A case study].

During neuroleptic treatment with clozapine, transitory reversible rise in transaminases is not rare, while severe parenchymal damage with icterus has not previously been reported. Such a case is now described: a 54-year-old woman developed clozapine-induced cholestasis with severe liver damage.

Antipsychotic Agents↗
PubMed1987

Alteration by histamine of the sympathetic nerve-mediated contractions in the bovine ovarian follicle wall in vitro.

The histaminergic effect on electrically induced contractions and tritium release was studied in vitro, using strips from the wall of mature bovine ovarian follicles. Follicular fluid and blood plasma from the animals were analysed for electrolyte, bicarbonate, glucose and total protein concentrations in order to compare them with the concentrations of these components in the Krebs-Ringer solution used in the experiments. Electrical field stimulation (EFS) of the follicle strip caused a contraction which was completely blocked by tetrodotoxin and was predominantly of adrenergic origin since phentolamine, in contrast to atropine, blocked the response. The neurogenic response was inhibited by histamine in a concentration-dependent way via the H1-receptor since the H1-antagonist, pyrilamine, counteracted the inhibitory effect of histamine while the H2-antagonist, cimetidine, potentiated the effect. This histaminergic response of EFS-induced contractions could be reproduced in experiments where the H1-agonist, 2-methylhistamine, was inhibitory while the H2-agonist, 4-methylhistamine, had no obvious influence on the twitch response. Histamine reduced the contractile response to exogenous noradrenaline via the H1-receptor, because pyrilamine counteracted, and cimetidine potentiated the effect. The histamine-induced depression of the motor response to EFS and exogenous noradrenaline was probably due to a postjunctional effect mediated by the H1-receptor. Experiments utilizing [3H]noradrenaline release during EFS did not suggest prejunctional effects of histamine. Chemical determinations on follicle fluid and plasma showed that the artificial follicular fluid imitated well the environmental conditions the follicle wall is exposed to in situ.

Animals↗
PubMed1987

[Functional significance of lung siderosis in electrode welders].

56 electric arc welders found in a cross-sectional study to show pulmonary siderosis in full size x-rays were clinically examined. Looking for the discussed functional, relevance of such lung diseases in welders the diagnostic program included spirometry, flow-volume-curves, body-plethysmography, single breath diffusion capacity, pulmonary compliance and ergooxytensiometry. The results are supporting that "lung siderosis" in welders is associated with slight functional deterioration in the type of interstitial lung diseases.

Electrodes↗
PubMed1987

[Syncopes of unclear etiology. Diagnosis, follow-up observation and pacemaker therapy].

Clinical findings after syncopal attacks were evaluated in 295 inpatients for examining their clinical significance and the course and prognosis in syncopes of unclear aetiology. This was done after having defined the criteria for "very probable" and "possible" causes of the syncopes. A "typically rhythmogenic" anamnesis had a sensitivity rating of 79%. Long-term ECG proved the most frequent contribution to clarification. Doppler examination of the carotid artery was hardly relevant. Patients with tachycardia usually suffered from cardiac disease (coronary heart disease or cardiomyopathy). Bradycardia predominated in patients with a clinically "healthy" heart, especially in elderly patients. An overall percentage of 37% of the cases could not be clarified despite thorough clinical examination using all available diagnostic tools. Follow-ups over two years and outpatient examinations revealed a favourable prognosis in patients whose syncopes had remained unexplained: No further syncopes had occurred in 75% of these patients over a period of two years. In 12% of the subjects the cause was identified by the follow-up examinations. In 95.5% of the patients subjected to pacemaker treatment no syncopes recurred. A relatively small proportion (19.5%) of the patients with unclarified syncopes continued to suffer from syncopes, the aetiology of which could not be determined during the 2-year follow-up period. This group of patients would require better diagnostic techniques, e.g. long-term ECGs over several days or long-term EEGs.

Adolescent↗
PubMed1987

On the viscosity behaviour of field bean protein isolates in dependence on their degree of acetylation.

The increase of apparent viscosity when protein concentration is raised becomes more and more distinctly pronounced with an increasing degree of acetylation and is displaced at lower protein concentrations. Investigations of the influence of temperature on viscosity behaviour are therefore carried out on the basis of comparable initial viscosity. 20 min heat treatment at different temperatures shows that above 40 degrees C the order of magnitude of the temperature-induced increase in viscosity depends decisively on the degree of acetylation. With an increasing degree of acetylation there is a comparably stronger increase in viscosity. An increase of viscosity is also linked to increasing duration of the heat treatment. The higher the degree of acetylation, the greater--related to a defined duration of heat treatment--is the growth of viscosity. During the heating phase in cyclical temperature tests a viscosity maximum is formed at 60 degrees C, which becomes more and more distinctly pronounced with an increasing degree of acetylation. From computerised evaluation of flow curves it is generally established that the complexity of flow properties increases with increasing degree of acetylation, increasing concentration of protein and the effect of heat.

Acetylation↗
PubMed1987

[Computer-assisted identification of basic substances].

The potential applications of a personal computer with integrated database software in toxicologic analysis are discussed. A toxicologic database including 370 basic compounds, is presented that was built up without knowledge of a higher programming language and was used as a base for drug identification in normal analysis by PC, DC and GC.

Chromatography, Gas↗
PubMed1987

Morphometric investigation of the microvascular system of pancreatic exocrine and endocrine tissue in the rat.

Morphometric data were obtained from the microvasculature in exocrine and endocrine tissue of the rat pancreas. Two groups of anesthetized rats (100 and 300 g body wt, respectively), received intravenous injections of fluorochrome-coupled globulins in order to label the entire vascular system. After circulation of fluorescein-isothiocyanate (FITC)-globulin through the vascular system for 30 min and lissamine rhodamine B 200 (RB 200)-globulin for 5 min, the pancreas was frozen rapidly. In frozen sections of the organ, both dyes showed the same intravascular distribution. The mean number of sectioned vascular elements was 970 +/- 40/mm2 in the exocrine parenchyma and 1430 +/- 60/mm2 in islet tissue. The cross-sectional area fraction of the microvascular system, which is equivalent to the intravascular volume fraction, amounted to 0.027 +/- 0.001 mm2/mm2 in the exocrine system and to 0.061 +/- 0.002 mm2/mm2 in the endocrine pancreas. The corresponding values for microvascular surface area (mm2/mm3) were 18.0 +/- 0.8 (exocrine tissue) and 34.2 +/- 2.0 (endocrine tissue). Mean diameters of vessels up to 10 microns in exocrine tissue amounted to 5.5 +/- 0.2 and 6.1 +/- 0.1 microns in exocrine and endocrine tissues, respectively; when all vessels up to 30 microns in diameter were considered, these values amounted to 5.7 +/- 0.2 and 6.7 +/- 0.2 microns, respectively. Especially in light of the fact that flow rate was observed to be much higher in islets than in acini, the present results support the existence of an insular microcirculatory system which is specialized in terms of its exchange capacity.

Animals↗