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Biomedical subjects

R Heinrich

Publications and source records attributed to R Heinrich.

At least 145 records · Page 8Linked to original sources
PubMed1984

[Early hemodynamic reactions of an ionic low osmolar and a nonionic contrast medium].

In eighty patients with different cardiac diseases the theoretically claimed reduced cardiovascular side effects in ionic and non-ionic low osmolar contrast media compared to those in conventional ionic and high-osmolar contrast media were tested during heart catheterization. The randomized application showed that there were only few reactions during left ventricle angiography and they did not differ between various ejections, while during selective coronary angiography in most cases heart rate and aortic pressures dropped significantly (p less than 0.05). These alterations were significantly (p less than 0.05) stronger in the conventional ionic and high-osmolar ioxitalamat (Telebrix 350) than in the ionic and non-ionic low-osmolar ioxaglat (Hexabrix) or non-ionic low-osmolar iopamidol (Solutrast 370).

Adult↗
PubMed1983

[Seroprevalence of Q fever in an endemic area of southern Germany].

In a random study among inhabitants of a village in a region of South Germany in which Q fever is endemic, seroprevalence and the significance of known risk factors for Q fever were investigated. Of the 1150 inhabitants, 948 (older than 14 years, resident in the endemic region for more than six months) were included in the study (target group). Within eight months 715 subjects (total group) were actually tested. The total group did not differ from the target group demographically. There were 136 seropositive persons (19%) with a dominance of males (n = 86). Relatively at risk of seropositivity were: males, aged 14-19 years, women, aged 40-49 years; those resident less than 200 m from the next farmhouse; agricultural workers; those in contact with animal products and farm animals. The known greater risk for males is, as shown in these results, due to the specific agricultural activity of this population group, with increased contact with lamb meat, pigs and chickens.

Adolescent↗
PubMed1983

[Bronchopulmonary infiltrates in chronic inflammatory bowel disease].

High temperatures, night sweat, chest pain, cough and dyspnoea suddenly occurred in a 54-year-old patient. The serious disease was accompanied by variable pulmonary infiltrations. Chemical pathology showed maximally increased sedimentation rates, slight leucocytosis and anaemia. Complete serology was negative. The occurrence of large intestinal ileus required laparatomy and after commencement of treatment with steroids the overall state improved, pulmonary symptoms disappeared, and radiographically demonstrable infiltration were clearly regressing. Histology revealed presence of acute ulcerative colitis. Lung infiltrates probably represented extraintestinal manifestation of the chronic inflammatory bowel disease. In contrast to experience from the literature lung infiltrations in this case preceded clinical manifestations of the underlying disease.

Colitis, Ulcerative↗
PubMed1983

Occupational exposure to hexachlorocyclohexane. VI. Metabolism of gamma-hexachlorocyclohexane in man.

Metabolism of gamma-Hexachlorocyclohexane (HCH) was studied examining 21 workers producing this insecticide. Using gas chromatography in combination with ECD and mass spectrometry 14 mono-, di-, tri- and tetrachlorophenols were identified in the urine samples of the workers. Seven dihydroxychlorobenzenes of still unknown configuration were detected by mass spectrometry. Ten of the more abundant metabolites, di-, tri- and tetrachlorophenols were determined quantitatively in all urine samples. 2,4,6-; 2,3,5- and 2,4,5-trichlorophenol turned out to be the main metabolites of gamma-HCH. They were excreted in nearly equal quantities. On account of their potential liver toxicity, the determination of chlorophenols in urine should be part of a biological monitoring program of HCH-exposed persons.

Adult↗
PubMed1983

Dopamine-beta-hydroxylase activity of the cat carotid body under different arterial O2 and CO2 conditions.

To determine the importance of dopamine and noradrenaline as neurotransmitters during chemoreception in the cat carotid body we investigated the contents of both compounds as well as the activity of dopamine-beta-hydroxylase (DBH) under different arterial PO2 and PCO2 conditions. The superior cervical ganglion was used as a control organ. In the carotid body and the ganglion an inverse relationship exists between the catecholamine content and the DBH activity. The carotid body has a high catecholamine content with a low DBH activity whereas the superior cervical ganglion has a low catecholamine content and high DBH activity. Hypercapnia did not produce any significant change in the catecholamine content or in the DBH content of the carotid body. However, in comparison with hyperoxia, hypoxia produced a significant change (p less than 0.05) in the noradrenaline content without changing the DBH activity. The dopamine content under these conditions did not change significantly. The results may indicate that the high catecholamine content of the carotid body is the result of a high retention and/or low rate of degradation rather than of a high rate of synthesis.

Animals↗
PubMed1982

Occupational chronic exposure to organic solvents. X. Biological monitoring parameters for methanol exposure.

Twenty persons occupationally exposed to methanol were examined according to their methanol levels in blood and urine and their formic acid excretion. An 8-h exposure to a methanol concentration of 93 ml/m3 (geometric mean) in the air at the working area caused average methanol levels in blood and urine of (8.9 +/- 14.7) mg/l and (21.8 +/- 20.0) mg/l, respectively, and a mean formic acid excretion of (29.9 +/- 28.6) mg/l. These average concentrations for the exposed group showed statistically significant increases compared to those of a control group. For the methanol workers we succeeded in correlating their methanol levels in blood and urine. When considering the possible application of these parameters for biological monitoring, difficulties were encountered, especially for the individual case from the overalapping range in the concentrations of exposed and unexposed persons for each of the applied parameters. This range is minimum for the methanol concentration in urine. About 80% of the urinary levels from the methanol workers lies above the upper limit within the control group range. Based on our results a rough estimate shows the corresponding methanol content in urine to be about 40 mg/l for an 8-h exposure at 200 ml/m3 (German MAK value).

Formates↗
PubMed1982

Dynamics of non-linear biochemical systems and the evolutionary significance of time hierarchy.

Several non-linear reaction networks are analyzed in order to study the influence of time hierarchy on the dynamics of biochemical systems. The analysis is based on the assumption that the separation of the time constants within metabolic systems is a direct consequence of strong differences of enzyme concentrations. Therefore, as variable system parameters, only the enzyme concentrations are considered. By investigation of the stationary states of various three-component models with feedback-activation bifurcation diagrams within a two-dimensional parameter space, the enzyme simplex, are constructed. The diagrams contain the information about the number of stationary states, their stability properties as well as the type of motion expected at different parameter combinations. The results support the hypothesis that systems with separated time constants generally show a simple dynamic behaviour. Complex motions can be expected mainly for systems without time hierarchy, which are characterized by parameters located within the centre of the enzyme simplex. Quantitative measures for the time hierarchy and the complexity of the dynamics are derived. It is supposed that the separation of time constants is a main feature of the evolution of biochemical systems. The hypothesis is further supported by the consideration of the time hierarchy of the glycolytic pathway.

Biological Evolution↗
PubMed1981

Occupational exposure to hexachlorocyclohexane. V. Gas chromatographic determination of monohydroxychlorobenzenes (chlorophenols) in urine.

A sensitive and specific gas chromatographic method is described for the simultaneous determination of ten chlorinated phenols that appear in the urine of persons exposed to hexachlorocyclohexane (HCH). The phenolic compounds in the urinary samples are hydrolysed in an acidic medium and derivatised with acetic anhydride. This sample treatment permits routine application. The stationary phase (8% DC 200 on Chromosorb G AW-DMCS) possesses a high separating capability for the acetic esters of the chlorophenols. The detection limits lie between 4.9 and 18.6 micrograms/l and allow determinations even in the environmentally interesting concentration range. The recoveries determined using aqueous standards range between 87 and 119% and the relative standard deviations are between 4.4 and 10.1%.

Chlorophenols↗
PubMed1981

Intravenous chlormethiazole- haemolysis with concentrated solutions.

Since the current clinical concentration of chlormethiazole solutions (0.8%) may require the infusion of large volumes of fluid, it was decided to examine the effects on haemolysis of infusing higher concentrations of chlormethiazole into a central vein. Approximately one gram of chlormethiazole was infused into the inferior vena cavae of six anaesthetised greyhounds over each half hour using, successively, 0.8%, 1.2%, 2%, 5%, 10%, and 20% solutions of chlormethiazole. Free plasma haemoglobin levels were measured at five minute intervals, and blood chlormethiazole levels at 15 minute intervals. A rapidly progressive haemolysis occurred when the 5 or 10% solutions were infused. In a further four greyhounds, one gram of chlormethiazole was infused over each half hour using a 0.8% solution, whilst progressively hyperosmolar dextrose solutions were infused at the same rates in succeeding half hours as the concentrated chlormethiazole solutions had been infused in the first six dogs. No haemolysis occurred in these control animals. Chlormethiazole blood levels were similar in each group. Loss of chlormethiazole into the infusion tubing was examined and found to be 20% for the 0.8% solution, and 10% for the 1.2% solution, but was insignificant with the other subsequently infused concentrations of chlormethiazole. It is concluded that rapid progressive haemolysis occurs in association with the infusion of chlormethiazole solutions when concentrations of greater than 5 or 10% are infused into the inferior vena cavae of anaesthetised greyhounds.

Anesthesia↗
PubMed1981

[Mathematical modelling of glycolysis and adenine nucleotide metabolism of human erythrocytes. I. Reaction-kinetic statements, analysis of in vivo state and determination of starting conditions for in vitro experiments].

A mathematical model of energy metabolism of human red cells is presented, which includes besides the glycolytic reactions the adenine nucleotide metabolism. The model is based on the network of chemical reactions, the thermodynamic equilibrium constants of fast reversible reactions and on the kinetic equations for irreversible enzyme reactions. The model consists of a system of 16 differential equations and allows the mathematical evaluation of metabolic levels in the steady state of energy metabolism corresponding to the in vivo state erythrocytes with the kinetic data for the enzymes derived from in vitro experiments. The dependence of the levels of metabolites in the steady state on the activity of some enzymes is analysed to characterize the regulatory properties of the system. The comparison of the steady state levels of the model with experimental data makes it possible to estimate values of some controversial enzyme parameters. Estimates of the kinetic parameters of the following intracellular processes are presented: 1) rate constant of AMP-phosphatase, 2) maximum rate of adenylate deaminase, 3) activity of adenine phosphoribosylpyrophosphate transferase and 4) adenosine transport through the cell membrane. The simulation of the preparatory phase before incubation of erythrocytes indicates, that the model also permits to compute the time course of changes of levels of metabolites. To solve the initial problem the stiff differential equation system is integrated numerically by an efficient program without the application of the quasi-steady-state approximation.

Adenine Nucleotides↗