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R Schmitz

Publications and source records attributed to R Schmitz.

At least 55 records · Page 3Linked to original sources
PubMed1989

The pomander.

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History, Ancient↗
PubMed1988

Interpretation of [3H]ouabain binding in guinea-pig ventricular myocardium in relation to sodium pump activity.

1. The attempt was made to analyse the complex [3H]ouabain binding curves obtained in intact cardiac ventricular preparations electrically stimulated at different frequencies. The result of this analysis was used to draw conclusions from the binding curves on the frequency dependence of sodium pump activity. 2. [3H]Ouabain binding to isolated, electrically stimulated (1.5 Hz) ventricular strips of guinea-pig hearts was investigated. The positive inotropic effects were studied in separate experiments. Specific [3H]ouabain binding barely reached an equilibrium within 3 h of incubation. A binding curve was constructed using the equilibrium values of specific [3H]ouabain binding obtained at different ouabain concentrations. This binding curve revealed a concentration-proportional component at positive inotropic concentrations and a saturating component at high, toxic concentrations. At very low, inotropically ineffective ouabain concentrations, however, binding values were higher than expected from a linear relationship between ouabain concentration and binding. 3. The peculiar shape of the binding curve could be largely accounted for by a mathematical model, which takes into consideration biochemical properties and physiological regulation of the sodium pump. The model predicts a concentration-proportional pattern of binding which takes place in the non-toxic ouabain concentration range. The slope of the concentration-proportional component of the binding curve should represent a measure of sodium pump activity. 4. Investigation of binding curves at various stimulation frequencies revealed that, as predicted by the model, the slope of the concentration-proportional component of the binding curves was increased and the maximum non-toxic equilibrium binding was decreased with increasing beat frequencies. 5. Quantitative evaluation of the binding curves led to the conclusion that sodium pump activity is a linear function of stimulation frequency in guinea-pig ventricular preparations, the activity in resting preparations amounting to about 15% of the maximum activity. Comparison of the present results with former studies on sodium pump function suggests that [3H]ouabain binding reflects steady-state sodium pump activity. If the complex pattern of binding curves is taken into consideration, [3H]ouabain binding measurements may serve as a means of studying sodium pump function.

Animals↗
PubMed1987

Proteolytic enzymes as new tumor markers in rats with benzopyrene sarcoma.

Proteolytic enzymes may facilitate tumor invasion by histolysis of the surrounding tissue and inhibit tumor growth in the course of host defense reactions. Using chromogenic peptide substrates, we looked for proteolytic activities related to carcinogenesis in serum and tumor extracts of rats with benzopyrene sarcomas. The enzymatic hydrolysis of two substrates (Boc-(Ala)2-p-nitroanilide and Bz-Lys-p-nitroanilide) was significantly decreased in the sera of tumor-bearing animals (P less than 0.01). This loss of proteolytic activity was highly correlated to tumor growth, so these enzymes might become useful as new tumor markers. In the tumor extracts, we found the Boc-(Ala)2-p-nitroanilide cleaving activity increased with tumor weight, whereas the Bz-Lys-p-nitroanilide cleaving activity did not exhibit any correlation to tumor growth. Studies on the potential use of these results for cancer patients are indicated.

Aminopeptidases↗
PubMed1987

Proteolytic enzymes as new tumor markers in chemical carcinogenesis of intestinal tumors.

Because the role of proteolytic enzymes in carcinogenesis is not yet well understood, we studied two arylamidases cleaving Boc-(Ala)2-p-nitroanilide and Bz-Lys-p-nitroanilide in the sera of rats during azoxymethane (AOM)-induced development of bowel carcinomas. Both proteolytic activities exhibited similar patterns: During administration of the carcinogen they increased up to 2.1-fold (Boc-[Ala]2-Nan) and 1.7-fold (Bz-Lys-Nan) the activity of the control group (P less than 0.05). Subsequently they decreased, passing the normal range between weeks 16 and 20 after the first AOM treatment and then diminishing continuously with increasing manifestation of tumors. At week 24 when the last animals were sacrificed enzyme activities were only 36.5% and 43.7% of the controls (P less than 0.05). The early increase may be related to direct effects of the carcinogen. The decrease of serum activity in the further course, however, seems to be a typical event of invasive tumor growth, because a similar loss of activity was also observed in rats with benzopyrene sarcomas. We conclude that both arylamidases may become useful as nonspecific tumor markers.

Aminopeptidases↗
PubMed1986

LT4-monopreparation versus LT4-LT3-compound preparation in the treatment of diffuse endemic goitre.

Fifty-four patients with diffuse non-toxic goitre were observed before and under therapy either with 125 micrograms LT4 (group A) or 75 micrograms LT4 + 15 micrograms LT3 (group B) in a prospective double blind study, using 1-, 3- and 6-months controls. Changes in goitre size have been estimated by ultrasonic scanning. Both treatment forms provided a significant reduction of goitre size, even after 1 month of therapy: a 20%-decrease in group A and 16% in group B. The 6-month reduction was about 30% in group A and 27% in group B. Between the 2 groups there were no differences in the reduction of volume. The suppression of the TSH-response to TRH was identical in both groups, too. In group A there was a predominant increase of the TT4- and FT4-serum levels, both reaching the hyperthyroid range. In group B there was a predominant increase of the TT3- and FT3-serum levels and a slight increase of the FT4-levels. The TT3- and FT3-serum levels also exceeded the upper normal range. As the blood samples were drawn about 2 h after medication, acute hormone resorption influenced these data. In the 3-month controls only there was a significant correlation between the reduction of the thyroid volume and the suppression of TSH-release. In the 6-month controls we found a weak correlation of the reduction of volume and the decrease of the pertechnetate uptake value.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗