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H Steinhart

Publications and source records attributed to H Steinhart.

17 recordsLinked to original sources
PubMed1992

[Intake of trans-isomeric fatty acids--an evaluation on the basis of data of the national consumption study in 1991].

The intake of trans octadecenoic acids is estimated by a national consumption assay. The daily intake in West Germany differs between 3.4 g for women and 4.1 g for men. The consumption of trans fatty acids decreased in the last years, due to the progress in food technology and changes in nutritional habits. The main sources of trans fatty acids are partially hydrogenated vegetable fats just as well as ruminant and dairy fats.

Adolescent↗
PubMed1992

[Treatment and treatment results of mouth floor cancers].

The records of 68 patients with cancer of the floor of the mouth were reviewed. 56 patients underwent surgical management, 51 of them got additionally postoperative radiation. The tumour-specific five years' survival for patients with operation was 46%, 57% of treatment failures developed from local recurrence of the tumour. In 52% of all cases there was a spread to the lymphatic system in the histological evaluation. There was high incidence of false negative clinical examinations of the neck. Conservative neck dissection was the procedure of choice for clinically positive lymph nodes and for the elective management of the neck. Only advanced tumours showed involvement of the mandibular bone. Therefore a conservative management of mandibular resection was preferred. Radical tumour extirpation and histological controlling with serial sectioned specimens are methods of avoiding local tumour recurrence.

Carcinoma, Squamous Cell↗
PubMed1990

Separation of phospholipids in bovine tissue with disposable silica gel extraction columns.

A simple and elegant method using disposable silica gel columns has been developed to separate the phospholipid fraction in beef muscles from other fatty acid containing lipids. By this method, 10 samples can be cleaned up simultaneously in less than 2 h. It does not require complicated equipment. The separation of the phospholipid fraction is necessary in order to characterize it by chemical means, for instance to determine the fatty acid pattern. Recovery and reproducibility were proved with a model meat system. Purity was proved with a model system and biological samples.

Animals↗
PubMed1989

In vivo indicator dilution kinetics of PAH transport in dog kidney.

In vivo multiple indicator-dilution (MID) data were analyzed using a computer-assisted mathematical model of transepithelial cell transport to determine p-aminohippuric acid (PAH) transport kinetics across the proximal tubular antiluminal (ALM) and luminal (LM) membranes. A bolus of 125I-labeled albumin (plasma reference), [14C]creatinine (interstitial reference), and tracer [3H]PAH was injected into the left renal artery of anesthetized mongrel dogs (n = 21), and immediate serial sampling of the left renal venous and left and right urine outputs was performed (control). MID runs were then repeated in the same dog following intravenous infusion of unlabeled PAH. For all plasma PAH concentrations ([PAH]P), the steady-state unidirectional flux coefficients were calculated at the ALM and LM. The computer-derived unidirectional flux coefficients were in keeping with active ALM transport and passive, carrier-mediated LM transport. The Km calculated for ALM uptake (interstitium to cell) was 0.51 mM. PAH transport was completely inhibited by probenecid. As [PAH]P increased, the renal vein mean transit time ratio t[3H]PAH/t[14C]creatinine was greater than 1.0, indicating backflux from cells into the interstitium, then declined toward unity, as ALM and LM transport became saturated. This study, which used PAH as a model substrate demonstrated the feasibility of utilizing computer-assisted mathematical models to quantitate the kinetics of transepithelial transport from in vivo experimentation.

Animals↗
PubMed1987

Determination of carazolol in tissues of pigs by high-performance liquid chromatography.

A new and sensitive method is described for the determination of the beta-receptor blocker Carazolol, 4-(2-hydroxy-3-isopropylaminopropoxy)-carbazole, in different animal tissues. The procedure comprises extraction of Carazolol from tissue, clean-up by Kieselgel adsorption and high-performance liquid chromatographic separation with fluorimetric detection. The determination limit is 0.48 microgram/kg sample. The method has been verified by measuring Carazolol in liver, kidney and filet of a fattening pig treated with Carazolol before slaughtering.

Adrenergic beta-Antagonists↗
PubMed1976

Activation of pepsin (EC 3.4.4.1) by heavy-metal ions including a contribution to the mode of action of copper sulphate in pig nutrition.

1. Kinetic experimetns were done with pepsin (EC 3.4.4.1) using haemoglobin as a substrate in the presence of different metal cations. 2. The activation of peptic hydrolysis with higher concentration of cupric ions added to the reaction mixture was determined from turnover-rate curves in experiments with constant substrate concentration. With a Cu2+ concentration greater than 1.67 X 10(-4) M activation was obtained. 3. Nickel ions at a concentration of 8-33 X 10(-4) M and at higher concentrations also increased pepsin activity. Additions of ferrous ions and zinc ions had no effect. 4. Experiments were done using variable substrate concentrations in the presence of different Cu2+ concentrations. The concentrations of haemoglobin ([S]) at half maximum velocity were determined. The double-reciprocal plots of [S] v. reaction velocity (v) (i.e. 1/[S] v. 1/v) had no common intersection point. Therefore the kinetics did not correspond to any of the known kinetics. The activation brought about by Cu2+ cannot easily be explained by the study of the kinetics. Certain simple explanations of the phenomenon can be eliminated.

Animal Nutritional Physiological Phenomena↗
PubMed1976

[Interactions between various transition elements in their effect on pepsin activity].

Kinetic experiments were made with pepsin in the presence of Cu2+ ions and additional Fe2+, Ni2+ or Zn3+ ions as sulphates. As a parameter of the pepsin activity the turnover-rate curves were determined with haemoglobin as a substrate. An important activation of the pepsin was obtained by Cu2+ additions of 5-10(-4) mole/1. When Cu2+ and Fe2+ ions were added to the reaction mixture at the same time, an additive effect of both metal cations was observed. A competitive effect of both metal cations was found in the combination of Cu2+/Ni2+ ions. Zn2+ addition did not influence the activation of pepsin caused by Cu2+ ions.

Animals↗
PubMed1976

[The effect of various pH values on in vitro peptic digestion of proteins in the presence of Cu2 ions].

Studies were carried out to investigate the effect of different pH values on the peptic digestion of soya protein in the presence and in the absence of Cu2+ ions. The studies were performed in vitro at a pH of 2.2 and 3.2, with 2.96 X 10(-5) mole of Cu2+ ions present in 11 of the reaction mixture. The reaction was carried out in a digestion apparatus permitting dialysis of the cleavage products. Different parameters were used as criteria of digestion, viz. the quantity of N contained in the reaction vessel (residue) and in the resulting dialysis products as determined by Kjehldahl microanalysis and automatic amino acid analysis, the proportions of digestion products found in the different molecular ranges after partition of Sephadex G 75 and the composition of amino acids in the cleavage products. From the distribution of the reaction products on the residue and dialysis products and on the different molecular ranges it was found that additions of Cu2+ ions at pH 2.2 produced a considerable inhibition of digestion. With a rise in pH to 3.2 peptic digestion decreased even without the addition of Cu2+. Supplementation of Cu2+ ions produced only a slight additional effect in the molecular range termed "exclusion limit". In the case of the amino acids tyrosine and phenylalanine it was found that an increase in pH changed the composition of peptides within the different molecular ranges. Additions of Cu2+ had no influence on the amino acid composition.

Copper↗
PubMed1975

[On the complex formation of proteins with cu ions under acidic conditions].

In order to determine the influence of copper additives on the protein digestibility, the complex formation of proteins with Cu ions under acidic conditions (pH=2.2) was investigated. Isolated soja-protein (300 mg) resp. pepsin was mixed with 10 mumol (2.49 mg) CuSO4-5H2O and dialysed against low molecular complexing agents with increasing affinity towards copper ions. The experiments with soja-protein showed, that most of the Cu ions dialysed (97% of total Cu2+ content) without any addition of complexing agents, pepsin, however, had a lower percentage (83% of total Cu2+ content). The remaining copper ions in pepsin could only be removed by alanin and ammonium-tetramethylendithiocarbamate. Therefore it is concluded, that in the acidic range Cu ions only form complexes with pepsin, but not with soja-protein. This effect is due to the very low isoelectric point of pepsin. The determination of iron, nickel, and zinc in native proteins revealed, that at pH=2.2 iron and nickel are stronger linked to pepsin than to soja-protein; only zinc was loosely bound to both proteins.

Copper↗