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Biomedical subjects

R Strasser

Publications and source records attributed to R Strasser.

16 recordsLinked to original sources
PubMed1992

Proof for piroximone's inotropic influence; can it safely be used in coronary artery disease? Analysis of end-systolic pressure-volume relations (conductance technique).

Improved contractility after applying piroximone (PIR) a new phosphodiesterase III inhibitor drug, is difficult to prove clinically. However, augmented contractility could increase the risk of myocardial ischemia when used in coronary artery disease (CAD). Analysis of the end-systolic pressure-volume relationship (ESPVR) as a load-independent parameter of the contractile left ventricular (LV) function allows for differentiation of PIR's effects: contractility vs. unloading. We therefore analyzed ESPVR and LV function in 16 CAD patients before and after PIR, 0.75 mg/kg intravenously. Emax increased by 39% (9/16 patients) and loops of the ESPVR (16 patients) moved leftward, indicating improved contractility. The difference in percent change PIR versus control (16 patients) demonstrated augmentation of LV function via unloading: LV volumes decreased (ESV by 37%, EDV by 19%), LV-filling pressure by 34%, and systemic vascular resistance by 19%; dP/dtmax increased by 28%, LV efficiency by 24%, cardiac index by 21%, and ejection fraction by 13%. Pacing-induced anginal threshold increased by 47% after PIR while the ischemic postpacing LV-filling pressure and ST-segment changes tended to normalize under the drug's influence. Thus, PIR improved LV function both by unloading and by positive inotropy. Lack of PIR-induced angina and an increased anginal threshold indicate that the drug can be used safely in CAD patients as well. The analysis of ESPVR proved to be safe and reliable in identifying contractility during the diagnostic cardiac catheterization routine.

Aged↗
PubMed1991

How we teach ... key aspects of general practice using weekly seminars for GP trainees.

This article reports the author's experience of designing, teaching and evaluating a weekly lunchtime seminar series for Family Medicine Programme trainees in Gippsland. After reviewing the objectives of the seminar series and characteristics of the participants, the article outlines the process and content of the course. Particular emphasis is given to seven seminars on key aspects of general practice/family medicine, which highlight the differences between the models, concepts and attitudes of specialists and teaching hospitals, and those of general practice. Results of evaluations of seminar series from the beginning of 1986 to the present time are reported and discussed. Overall, the seminar series has been found to be effective in helping trainees to develop an appropriate understanding of key aspects of general practice/family medicine; facilitating the transition for trainees from hospital practice to general practice; and in encouraging active participatory learning.

Australia↗
PubMed1990

Myocardial catecholamine content after heart transplantation.

Myocardial catecholamine levels have not yet been determined in the transplanted human heart. We measured norepinephrine, epinephrine, and dopamine in endomyocardial biopsies from 19 short-term (organ age, 6.6 +/- 6 months) and five long-term (organ age, 62 +/- 2 months) heart transplant patients. Results were compared with those from 10 normal control subjects. In 17 of 19 short-term heart transplant patients, myocardial catecholamines were undetectable, indicating values below 0.1 pg/micrograms noncollagen protein, which was the detection threshold of our assay. In the remaining two patients, myocardial catecholamines (pg/microgram noncollagen protein) were norepinephrine (1.4 and 3.2), epinephrine (0.8 and 1.9), and dopamine (0.9 and 2.3), respectively. In the five long-term heart transplant patients, myocardial catecholamines were not detected. Catecholamine concentrations in 10 healthy control subjects were norepinephrine (10.3 +/- 2.9), epinephrine (0.36 +/- 0.51), and dopamine (0.52 +/- 0.40). Low myocardial norepinephrine levels (less than 20% of control values) with unexplained high levels of epinephrine and dopamine were found in single transplant patients. In most heart transplant patients, however, myocardial catecholamines were undetectable up to five years after transplantation, indicating that the adrenergic response of these hearts probably depends on variations in plasma catecholamines or cardiac beta-receptor density.

Biopsy↗
PubMed1990

Metabolic alterations in end-stage and less severe heart failure--myocardial carnitine decrease.

Severe tissue carnitine deficiency impairs fatty acid oxidation. In explanted hearts from patients with end stage heart failure a 57% carnitine decrease was found in comparison with healthy donor hearts (p less than 0.05). The reduction of myocardial carnitine levels affected all areas of the explanted hearts to a comparable extent. Carnitine decreases in patients with dilated cardiomyopathy or coronary artery disease were similar. Endomyocardial biopsies from patients with less severe heart failure due to cardiomyopathy (n = 28) or other myocardial diseases (n = 8) showed a 42% decrease of total myocardial carnitine (in nmol/mg non-collagen protein) in comparison with biopsies from patients with normal cardiac function (controls) (heart failure: 5.7, confidence interval 4.2-7.0; controls 9.3, confidence interval 7.6-12.0, p less than 0.005). Free myocardial carnitine in heart failure was also different from controls (heart failure: 4.2, confidence interval 3.7-5.3; controls 10.3, confidence interval 7.5-12.2, p less than 0.001). The decrease of free and total myocardial carnitine was comparable in dilated cardiomyopathy and heart failure due to other diseases. Alterations in myocardial carnitine content represent therefore non-specific biochemical markers in heart failure with yet unknown consequences for myocardial function.

Adult↗
PubMed1989

[Myocardial catecholamine content in heart failure--I: Regional distribution in explanted hearts. Comparison between dilated cardiomyopathy and coronary heart disease].

To quantify the myocardial catecholamine content in heart failure patients and to assess the regional distribution of catecholamines, we investigated norepinephrine and dopamine concentrations in explanted hearts from 34 patients in end-stage heart failure. 28 patients with cardiomyopathy were compared with six patients with coronary artery disease. In comparison with the right atria of a control group without heart failure, reduced myocardial norepinephrine contents (in pg/micrograms non-collagen protein (NCP] were found in all areas of the explanted hearts: controls: right atrium 17.6 +/- 6.6; cardiomyopathy: right atrium 7.1 +/- 7.9, right ventricle 4.4 +/- 2.7, septum 3.8 +/- 1.5, left ventricle 3.5 +/- 1.4. Coronary artery disease: right atrium 7.0 +/- 6.9, right ventricle 4.2 +/- 2.6, septum 3.6 +/- 1.4, left ventricle 3.4 +/- 1.4. Highest norepinephrine levels were measured in the right atrium. Right ventricle, septum, base and midventricular portion of the left ventricle had lower concentrations and were not different from each other. In contrast to reduced norepinephrine (NE) levels in all patients, dopamine (Dop) was inhomogenously elevated (only in a subgroup of 44%). Catecholamine contents in any two arbitrarily selected areas correlated significantly (NA: r = 0.53-0.77; Dop: r = 0.81-0.93, p less than 0.05 in all cases). The patients with heart failure due to dilated cardiomyopathy and to coronary artery disease did not differ in myocardial catecholamine levels or distribution. In end-stage heart failure a significant loss of myocardial norepinephrine independent from the underlying disease is found. It affects all areas of the hearts but does not equalize catecholamine content in ventricles and atria.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1976

A demonstration of energy transfer from photosystem II to photosystem I in chloroplasts.

Photosystem I activity of Tris-washed chloroplasts was measured at room temperature as the rate of photoreduction of NADP and as the rate of oxygen uptake mediated by methyl viologen in both cases using dichlorophenolindophenol plus ascorbate as the source of electrons for Photosystem I. With both assay systems the rate of electron transport by Photosystem I was stimulated approx. 20% by the addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea which caused the Photosystem II reaction centers to close. Photosystem I activity of chloroplasts was measured at low temperature as the rate of photooxidation of P-700. Chloroplasts suspended in the presence of hydroxylamine and 3-(3,4-dichlorophenyl)-1,1-dimethylurea were frozen to -196 degrees C after adaptation to darkness or after a preillumination at room temperature. The Photosystem II reaction centers of the frozen dark-adapted sample were all open; those of the preilluminated sample were all closed. The rate of photooxidation of P-700 at -196 degrees C with the preilluminated sample was approx. 25% faster than with the dark-adapted sample. We conclude from both the room temperature and the low temperature experiments that there is greater energy transfer from Photosystem II to Photosystem I when the Photosystem II reaction centers are closed and that these results are a direct demonstration of spillover.

Chloroplasts↗
PubMedDate not supplied

[Studies on the specific effects of serum and cytoplasm of the liver on the [3H]TTP-incorporation of isolated liver nuclei (author's transl)].

Previous authors have described that liver cytoplasm and serum from partially hepatectomized rats stimulate the DNA synthesis of isolated nuclei of liver cells. The aim of our investigation was to prove whether such stimulating effects are part of a specific regulation of growth. The sera and the cytoplasm supernatant 105000 x g) were isolated at several intervals after partial hepatectomy and laparotomy and were tested on isolated nuclei of liver cells from adult rats partially hepatectomized 20 hours before. The supernatants isolated at 8 and 16 hours after both partial hepatectomy and laparotomy have a significant stimulatory effect on the [3H]TTP-uptake by nuclei. The presence of serum (10%) causes a general elevation (75%) of the [3H]TTP-uptake by isolated nuclei. The sera isolated 4 to 12 hours after operation from both partially hepatectomized and laparotomized rats have an additional stimulatory effect on the [3H]TTP-uptake synthes of nuclei. In no case did the sera and liver cytoplasm of partially hepatectomized rats have a significantly different and therefore "specific" effect on the nuclear DNA synthesis. Additional experiments showed that frozen and thawed nuclei of liver cells respond only to the nutritive power but not to the stimulatory effects of the sera. Thus, thawed nuclei cannot be used for growth investigations.

Animals↗
PubMedDate not supplied

[Pyridinoline-containing collagen degradation products in urine in coxarthrosis].

High-performance liquid chromatography of collagen degradation products in human urine for diagnosis of osteoarthrosis was introduced by Macek and Adam (6) in 1987. The aim of the present study was to demonstrate the clinical usefulness of this method in a group of 20 patients with osteoarthrosis of the hip and 10 healthy volunteers. There were no significant differences in number or intensity of the detected signals between the two groups. The results of this study show that the determination of collagen degradation products is not useful for diagnosis or for the control of therapy in patients with osteoarthrosis.

Adult↗