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Biomedical subjects

H Hoppe

Publications and source records attributed to H Hoppe.

At least 73 records · Page 4Linked to original sources
PubMed1978

Influence of the contractile state of the heart of the preload dependence of the maximal rate of intraventricular pressure rise dP/dt max.

In canine heart-lung preparations the relation between dP/Dt max and end-diastolic pressure exhibits the steepest slope shortly after isolation of the heart. When the heart is deteriorating, the slopes of the preload dependence of right and left ventricular dP/dt max are progressively reduced, but increase again after application of calcium. The preload dependence of dP/dt max is influenced by the contractile state of the myocardium. In the right and left ventricle the change in preload dependence of dp/dt max show a linear correlation. In the individual heart the slopes of the preload dependence of dP/dt max and of aortic flow (representing ventricular function curves) change in a very similar manner with varying contractility. In 33 different isolated hearts the slopes of the preload dependence of the two parameters show a good correlation shortly after isolation of the hearts. The preload dependence of dP/dt max can not only be used for assessment of acute variations in in myocardial contractility, but appears also to be at least as reliable as the ventricular function curves for the evaluation of the basic contractile state of different hearts. This study further shows that if dP/dt max is used for evaluation of relative changes in contractility, the quantitative results are influenced by the end-diastolic pressure level chosen.

Animals↗
PubMed1978

Alkyl methane sulfonate mutation of diploid human lymphoblasts and Salmonella typhimurium.

Concentration dependence of mutation in equigenerational exposures to methyl, ethyl, propyl, and butyl methanesulfonates has been determined in diploid human lymphoblasts and Salmonella typhimurium. Forward mutation was measured at the hypoxanthine guanine phosphoribosyltransferase locus in human lymphoblasts and at the putative guanine phosphoribosyltransferase locus in S. typhimurium. Reverse mutation at the his G46 locus was also measured in S. typhimurium. This analysis and previous reports support the conclusion that S. typhimurium and mammalian cells are essentially equisensitive to the mutagenic effects of ethyl methanesulfonate when concentration and exposure time are taken into account. Comparison of forward and reverse mutation assays in S. typhimurium reveals no important differences in sensitivities for the four compounds studied.

Animals↗
PubMed1978

[Comparison of procedures for determining Michaelis-Menten parameters together with their standard deviations using simulated measurement series].

The direct non-linear fit of Cleland and different methods applying linear regression analysis to linearized forms of the Michaelis-Menten equation have been compared. Comparison was made with respect to bias and standard deviation of the estimated values of Km, Vm, deltak and deltav. The Lineweaver-Burk method, weighted by approximately v3, turned out to produce estimates nearly as reliable as the direct fit of Cleland if one does not know whether the velocities are subject to constant absolute or relative errors. The comparison was based on ca. 10000 simulated series of velocity measurements. Runs with fewer simulated measurement series showed that for comparing different evaluation methods, at least 1000 measurement series should be simulated in order to get reliable results.

Enzymes↗
PubMed1977

[An ion exchange method to determine free metal concentrations, adapted for use in biological fluids: methods and determination of (Mg2+)].

An ion exchange method for measuring concentrations of free (ionized) metal ions and its application to the determination of [Mg2+] is described. A surface sulfonated polystyrene material is used as the "twodimensional" cation exchanger. The sample-volume is 1 ml. About 50 determinations can be performed within 1 hr having a standard error of +/- (2-4)% in the optimal range of measurement. Advantages and disadvantages of the method compared with other ones are demonstrated and discussed. Free Mg2+ ion concentrations were measured in solutions containing pyrophosphate as well as haemoglobin and compared with those which were determined by equilibrium calculation or ultrafiltration.

Cation Exchange Resins↗
PubMed1977

[Long-term effect of hormonal contraceptives on the behavior of serum lipids].

In order to check the long-term effects of oral contraceptives used in the GDR on certain serum-lipid-fractions, triglycerides, phospholipids, total and free cholesterol, and beta-lipoproteins were determined in four groups of 15 women each, taking the contraceptive preparations Ovosiston, Nonovlon, Gravistat, and Deposiston. Determinations were carried out before and following 3, 6, 12, and 18 month of drug administration. Statistically significant increases of triglycerides occurred under the combined preparations, of phospholipids under Ovosiston and Deposiston and of the beta-lipoproteins under Ovosiston and Gravistat. Total cholesterol showed a slight decrease under all preparations tested. At present the prognostic significance of these slight alterations of serum-lipid-concentrations cannot be estimated completely.

Adult↗
PubMed1976

[Clinical ergometry in cardio-pulmonary functional disorders--a comparison of the usual ergometric technics].

It is reported on the results of a comparative examination of 18 patients with two usual ergometric methods (team pathophysiology of respiration and research group diseases of heart and circulation of the GDR). Referred to the intake of oxygen as a measure for the stress of the cardiorespiratory system by means of the ergometric methods recommended by the research group diseases of heart and circulation significantly higher minute volumes of the heart rate were established. Principal differences in the evidence of the two methods did not appear.

Adolescent↗
PubMed1976

[Analysis of thiabendazole in citrus fruits and bananas].

With regard to routine analyses in market control, the authors recommend two methods (according to the expected amounts of active principle) for the determination of thiabendazole residues on citrus fruits and bananas. The ultraviolet spectrophotometric method is preferable in determining thiabendazole contents of more than 1 p.p.m., if the cleaning operations described are respected. For the detection of thiabendazole and for the determination of amounts of less than 1 p.p.m. (the tolerance limit being 0.2 p.p.m. for pomes, berries, stone fruits, kernel fruits and also for potatoes) the thin-layer chromatographic method seems likewise to be suited (also in considering that it is semi-quantitative by nature); especially since the spectrophotometric method yields values by 0.2 p.p.m. too high (due to the measurement of residual absorption of vegetable constituents). The authors are of opinion that such an error must be considered to be too high for contents lower than 1 p.p.m.

Chromatography, Thin Layer↗
PubMed1976

Mutation of human lymphoblasts by methylnitrosourea.

The lag in phenotype expression of methylnitrosourea(MNU)-induced mutation to 6-thioguanine (6TG) resistance has been studied in a diploid human lymphoblastoid cell line. We find that a considerable period (8-12 days) elapses before new mutants appear in treated cultures; after 2 weeks, however, a stable maximum fraction is attained, as would be expected for a genetic mutation. We present preliminary data linking this phenotypic lag to the slow degradation rate of hypoxanthine-guanine phosphoribosyl transferase (HGPRT) and to an apparent requirement for very low (less than 0.2% normal) cellular HGPRT content in order for cells to be resistant to 10 mug 6TG/ml. A series of reconstruction experiments are presented, the results of which support the conclusion that selective pressures in the assay procedure do not bias the quantitative estimates of induced mutant fraction.

Cell Line↗
PubMed1976

Proton transport by phosphate diffusion--a mechanism of facilitated CO2 transfer.

We have measured CO2 fluxes across phosphate solutions at different carbonic anhydrase concentrations, bicarbonate concentration gradients, phosphate concentrations, and mobilities. Temperature was 22-25 degrees C, the pH of the phosphate solutions was 7.0-7.3. We found that under physiological conditions of pH and pCO2 a facilitated diffusion of CO2 occurs in addition to free diffusion when (a) sufficient carbonic anhydrase is present, and (b) a concentration gradient of HCO3- is established along with a pCO2 gradient, and (c) the phosphate buffer has a mobility comparable to that of bicarbonate. When the phosphate was immobilized by attaching 0.25-mm-long cellulose particles, no facilitation of CO2 diffusion was detectable. A mechanism of facilitated CO2 diffusion in phosphate solutions analogous to that in albumin solutions was proposed on the basis of these findings: bicarbonate diffusion together with a facilitated proton transport by phosphate diffusion. A mathematical model of this mechanism was formulated. The CO2 fluxed predicted by the model agree quantitatively with the experimentally determined fluxes. It is concluded that a highly effective proton transport mechanism acts in solutions of mobile phosphate buffers. By this mechanism; CO2 transfer may be increased up to fivefold and proton transfer may be increased to 10,000-fold.

Carbon Dioxide↗
PubMed1976

[Program for the computation of concentrations of free metabolites, metal ions and their complexes in chemical balance].

Enzymic reaction velocities often depend primarily on the concentrations of single free and complexed species rather than on the total metal and metabolite concentrations. For determining single species concentrations from total concentrations and complex stability constants, a program is described. The program may not only calculate the single concentrations, but also estimate their uncertainty due to the unavoidable uncertainty of complex stability constants. Making use of the ICT 1900 magnetic drum storage, it may deal with quite large complex patterns as are found in vivo.

Chelating Agents↗
PubMed1975

[Surgical treatment of cerebrovascular insufficiency due to extracranial obstruction of the carotid artery(author's transl)].

Reconstruction of the carotid artery was performed in 41 patients (between 1967 and 1974). All had had signs of cerebrovascular insufficiency. There was angiographic evidence of obliterating arteriosclerotic lesions in the carotid artery of 32 patients, carotid aneurysm in two, kinking of the internal carotid artery in four, and acute thromboses of the carotid artery in three. Early and late results indicate that best chances of success exist for stage II and III a cases. The high mortality rate in stages III b and IV (five of twelve patients) clearly shows that in these reconstruction of the carotid artery should be embarked on with caution, especially in the early stages.

Adult↗
PubMed1975

[Correlation of antenatal cardiotocogram and amnioscopy in the management of pregnant women with prolonged pregnancy].

In 125 women whose pregnancy continued for more than the calculated date of delivery 171 CTG were written and the parameters were analysed quantitatively. The lead of the CTG involved an amnioscopy in each case. The findings were compared with each other and with the condition of the newborn. The results show: 1. The normal value for the density of fluctuation-types (given by Rüttgers [15]) exceed in our cases. 2. A significant increase of density for the silent fluctuation-type was demonstrated well overdue of the calculated date. 3. There is no close correlation between the findings of the amniotic fluid and the characteristerics of CTG in excess of the fixed birthdate, even if the newborns show symptoms of overmaturity. The combined application of amnioscopy and prenatal CTG are considered as valuable methods to recognise the fetal risk early in post-term birth.

Adult↗
PubMed1975

[The problem of modifying X-chromatin frequency using hormonal contraceptives].

The ability of the sexual steroids to induce extragenital organ-effects is set in connection to the preovulatory decrease of x-chromatin frequency during the regular menstrual cycle as found by Schmidt and coll. [11]. Under modified techniques of investigation and exact criteria of selection, reproducibility of the results and the behaviour of the x-chromatin-frequency in the artificially controlled anovulatory cycle are checked. The absence of preovulatory decrease shows that a hormonal influence may be assumed.

Adult↗