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Biomedical subjects

W Schmidt

Publications and source records attributed to W Schmidt.

At least 703 records · Page 39Linked to original sources
PubMed1979

[The relationship between the doctor and pregnant women (author's transl)].

In a sample of 112 women in the third trimester of pregnancy a generally good quality of doctor-patient relationship was found by means of postal enquiry. This corresponds with the high degree of health-behavior of these women. A favorable assessment of the time spent correlated with the time the women had to wait before medical examination, and the imparting of information by the doctor. The women's need for information was very high. After the (marital) partner the doctor holds second place in importance as a competent adviser. But the women want him to take a considerably more important place as an advisor.

Attitude to Health↗
PubMed1979

On the environment and the rotational motion of amphiphilic flavins in artificial membrane vesicles as studied by fluorescence.

The incorporation of four amphiphilic flavins ("amphiflavins") as fluorescence markers bearing C18-hydrocarbon chains at various positions of the chromophore into artificial membrane vesicles has been investigated. The vesicles utilized were made from three different saturated phospholipids. The stability of the flavin-charged vesicles was found to be good over several days, depending somewhat on the temperature, the pH, and their concentration. A marked increase of the fluorescence quantum yield near the vesicle phase transition (crystalline leads to liquid crystalline) was found which was taken to indicate that the flavin nuclei are imbedded more deeply into the hydrophobic portion of the membranes. This is further supported by a hypsochromic shift of the near flavin UV-peak and the increase of absorbance at 450 nm upon melting. Rotational relaxation times of the various amphiflavins bound to the different vesicles are obtained from measurements of the fluorescence polarizations as a function of temperature. From these data, the microviscosities in the region of the chromophors are calculated. Measurements of the fluorescence polarization as a function of the solvent viscosity and vesicle phase (crystalline-liquid crystalline) indicate that below the phase transition the flavin nucleus is protected from the suspension medium by a lipid-water interphase, which softens above phase transition. The dependence of the flavin orientation and microenvironment on the position of the substitution of the aliphatic chain is reflected in the differences of the fluorescence yields and the shape of the emission spectra.

Flavins↗
PubMed1979

Radiation exposure due to 99mTc and 131I manipulated in syringes.

Dose rates around and at the surface of disposable polypropylene syringes of 1 and 2 ml volume filled with 99mTc and 131I solutions were determined by thermoluminescence dosimetry. Data for the efficacy of 0.5 and 1 mm lead shielding of 99mTc and for the dose contribution due to beta- -radiation from 131I are given.

Humans↗
PubMed1979

Interaction of phenylbutazone with racemic phenprocoumon and its enantiomers in rats.

The interaction of phenylbutazone with the enantiomers and racemic [3H]phenprocoumon was studied in male inbred Wistar-Lewis rats following a single i.v. dose of the three forms of phenprocoumon and chronic oral treatment with phenylbutazone (average plasma concentration of about 60 microgram/ml). Phenylbutazone augmented the anticoagulant effect of R(+), S(-), and R, S(+/-) phenprocoumon to a similar extent. The free fraction of drug in the plasma of the enantiomers and racemic phenprocoumon increased in the presence of phenylbutazone. However, the rate of elimination of total drug from plasma and liver and the distribution between liver and plasma of all three forms of phenprocoumon remained nearly unaffected by phenylbutazone. Thus there is no evidence for a stereoselective drug interaction between phenprocoumon and phenylbutazone. For racemic [oH]phenprocoumon it was possible to follow the kinetics of free drug in plasma and liver along with the time course of anticoagulant activity. In these studies, free drug concentrations in plasma and liver increased during treatment with phenylbutazone, but the elimination rate constant of free racemic phenprocoumon in plasma and liver remained essentially unchanged. Phenylbutazone markedly decreased the volume of distribution referenced to free drug and the clearance of free phenprocoumon (i.e., intrinsic metabolic clearance). Whereas the total (bound and unbound) drug concentration--effect relationship in plasma and liver was shifted to the left in rats treated with phenylbutazone, such shift was not seen in the free drug concentration--response relationship. In conclusion, the increase in the free concentration of phenprocoumon in plasma and liver and the concomitant decrease in the clearance of free drug are the mechanisms responsible for the marked and sustained enhancement of the anticoagulant effect which follows treatment with phenbutazone.

4-Hydroxycoumarins↗
PubMed1979

Differential accumulation of radiopaque contrast material in acute myocardial infarction.

The differential accumulation of radiographic contrast materials in ischemically damaged and normal myocardium was assessed with direct measurement (fluorescent excitation analysis) of the iodine content of tissue samples from dogs with 48 hour old myocardial infarctions. Tissue samples were obtained 10, 30, 60 and 180 minutes after the intravenous administration of 2 ml/kg body weight of diatrizoate meglumine and sodium (Renografin-76). At all time intervals, the iodine concentration of infarcted tissue was at least threefold greater than that of normal myocardium. At 180 minutes the ratio between iodine concentration in infarcted myocardium and that in normal myocardium was 8.5 and between that in infarcted myocardium and that in blood was 2.6. The iodine concentration in the liver was similar to or greater than that in the infarcted area at time intervals after 10 minutes. These results suggest that the intravenous administration of contrast material may facilitate the identification of acutely infarcted myocardium with computerized X-ray transmission tomography.

Animals↗
PubMed1979

Evaluation of myocardial ischemic damage of various ages by computerized transmission tomography. Time-dependent effects of contrast material.

The potential role of computerized transmission tomography (CTT) in the detection and quantitation of acute myocardial ischemic damage was assessed in 42 excised canine hearts at 2 hours, 8 hours, and 48 hours after coronary occlusion. The CTT scan detected by myocardial damage that was 2-48 hours old each time the presence of regional ischemia was confirmed by histochemical straining or epicardial electrocardiographic mapping. Intravenous administration of contrast material enhanced the x-ray attenuation of areas of ischemic damage of 8 and 48 hours duration compared with normal myocardium, but enhanced only normal myocardium in those of 2 hours duration. Volumetric estimation of the extent of damage from the CTT scans in dogs with ischemia of 48 hours duration showed a close linear relationship with the morphometric volume in the absence of contrast material. Quantitation of the area of ischemic damage from the CTT scan after contrast administration resulted in substantial underestimation of the volume of damaged tissue.

Animals↗
PubMed1979

Separation of the gonadotropic activity of crude choriogonadotropin from the inhibitory effect on lymphocyte transformation.

The effect of choriogonadotropin of different purities on the transformation of peripheral human lymphocytes was studied. Various crude hormone batches inhibited lymphocyte transformation in a dose-dependent manner, both in the mixed lymphocyte reaction and in the phytohemagglutinin-induced stimulation. The inhibitory activity, however, was found not to be correlated with the gonadotropic activity of the crude hormone batches (2660-4300 IU/mg). Choriogonadotropin (13 000 IU/mg), which was purified in 3 steps, showed no inhibitory effect except at high doses (greater than 5000 IU/ml final dilution). More detailed investigations provided evidence that in the first step of the choriogonadotropin purification procedure (batch adsorption of crude choriogonadotropin on SP-Sephadex C-50), the inhibitory activity can be enriched in a fraction (Fract. I) which displays a very low gonadotropic activity (less than 500 IU/mg). A further separation of Fract. I was achieved by isoelectric focusing as well as by chromatography on DEAE-Sephadex A-25. By these means, the inhibitory potency could be enriched more than 100-fold. The substances which display inhibition of DNA synthesis in lymphocytes were proven to act in a nontoxic way. A preliminary characterization of the strongly inhibiting substances which show a dose-dependent suppression of lymphocyte transformation by about 99%, showed that this effect is probably exerted via non-dialysable sialoglycoproteins. By a fourth purification step entailing a chromatography of purified choriogonadotropin (13 000 IU/mg) on SP-Sephadex C-50, a highly purified choriogonadotropin (14000 IU/mg) could be obtained which showed no inhibitory effect on lymphocyte transformation (in both mixed lymphocyte reaction and in phytohemagglutinin-induced stimulation) up to a dose of 43 000 IU/ml. The components which were removed from choriogonadotropin in this step seem to be immunologically identical with the strongly inhibiting substances isolated by isoelectric focusing. These investigations demonstrate that biologically active, highly purified choriogonadotropin is unable to inhibit lymphocyte transformation. The inhibitory activity of crude hormone can be enriched in choriogonadotropin-free fractions. Therefore, it is concluded that the inhibitory activity of crude hormone is not a property of choriogonadotropin itself.

Chorionic Gonadotropin↗
PubMed1979

[Experimental studies on the pathogenicity of tetanus spores regarding eucaryotic cell systems (author's transl)].

After injection of known numbers of viable tumour cells admixed with tetanus spores into the subcutaneous tissue between the shoulder blades the sigmoidal tetanus lethality curves of mice can be quantitatively analysed following the underlying growth of tetanus clostridia and tumour cells. We suggest that the "driving force" for exponential clostridial growth and toxin synthesis are oxygen-consuming clones of tumour cells. Our experimental data are in good accordance with a stochastic mathematical model which allows for computing the cloning probability of one single spore on the basis of a 1-mitosis-1-clostridium division-principle.

Animals↗
PubMed1979

[The microbiological cancer test--further studies with experimental mouse tumor tetanus and wound tetanus].

A re-evaluation of the specificity of the tumour-tetanus assay of the mouse was performed by analysing the wound-tetanus assay under comparable test conditions. This was achieved by injecting 1 X 10(6) viable Ehrlich carcinoma cells admixed with 1 X 10(2) tetanus spores subcutaneously, in a 0.1 ml dose volume or, 1 X 10(2) tetanus spores suspended in 5% CaCl2 solution, respectively. By comparison, these two groups of mice developed about the same tetanus mortality rates, however, following tetanus antitoxin therapy with 3 doses of 100 IU each day on days 0, 4 and 7 after infection, clinical signs of late tetanus exclusively belonged to tumour bearing animals. This typical tetanus behaviour may be explained by a spatial-temporal association between growing tetanus rods and proliferating cells of warm-blooded animals. In this manner tumour tissue can be differed from wound granulomatous tissue by way of permanently cloning stem cells.

Animals↗
PubMed1979

A critical revaluation of fibre arrangement in the mid-zone (stratum reticulare) of human corium.

Investigation of in situ fixed skin clearly showed distinct arrangement and orientation of collagenous fibre bundles clearly visible only after in situ fixation of whole bodies. Light microscopy seems especially useful to study gross fibre and fibre bundle arrangement, whereas scanning electron microscopy is better suited to study the finer details of fibres and fibre bundles and their arrangement. 2 main directions of fibre bundles were found. The orientation was corresponding to the main mechanical stresses exerted to the skin. No clear start and ending of the fibre bundles could be distinguished. They seem to be arranged in a 3 dimensional texture. Fibres are branching off from one bundle and merge again either with a branch of the same bundle or with a branch of another bundle, in a higher or a lower layer of this 3 dimensional texture. In addition to the 2 main directions of the bundle orientation thin fibres are penetrating the whole texture in various directions. This is especially prominent in regions where vessels, hairbulbs or glands are protruding into the stratum reticulare. A quantitative study of fibre and fibre bundle orientation using semithin sections is under current investigation applying an automatic image analysis system.

Aged↗
PubMed1979

[An experimental study on the function of fibrocytes].

By means of different types of fibrocytes (amnion connecting cells, fibrocytes of the substantia propria of the cornea, fibrocytes of the tendon, fibrocytes of the loose connecting tissues and fibrocytes of the ovary a varying disposition could be demonstrated for the accumulation of vital dies. The tests indicate that the transformation of fibrocytes into histiocytes (macrophagia) can be shown with certainty only in the less differentiated connected tissue cells of the amnion.

Amnion↗