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Biomedical subjects

A Aigner

Publications and source records attributed to A Aigner.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Performance modification in sports by beta receptor blockers].

Beta-adrenoceptor-blockers modify the physical performance due to their haemodynamic and metabolic effects. Additionally, these substances influence the concentration of serum-potassium and the thermoregulation. The reduction in heart rate yields to a diminished cardiac output resulting in a restricted muscular blood flow at submaximal and maximal exercise. After beta-blockade, O2-uptake at submaximal work load as well as maximal aerobic capacity is slightly reduced. Lipolysis is restricted by acute beta-blockade, but this effect can be compensated for by enhancement of catecholamine-independent lipolysis during chronic treatment with beta-adrenoceptor blockers. At submaximal loads, glycogenolysis is not influenced; at maximal exercise, glycogenolysis is reduced by non-selective beta-blockers but not by beta 1-specific ones. Arterial peak lactate concentration usually is diminished. After beta-adrenoceptor-blockade, the concentration of serum-potassium increases slightly, and sweat production is enhanced. Beta-adrenoceptor-blockers influence the performance in different sports to a various extent, due to the multitude of the different effects they take.

Adrenergic beta-Antagonists↗
PubMed1990

Transport, metabolism, and effect of chronic feeding of lagodeoxycholic acid. A new, natural bile acid.

Ursodeoxycholic acid, the 7 beta-hydroxy epimer of chenodeoxycholic acid, is more hydrophilic and less hepatotoxic than chenodeoxycholic acid. Because "lagodeoxycholic acid," the 12 beta-hydroxy epimer of deoxycholic acid, is also more hydrophilic than deoxycholic acid, it was hypothesized that it should also be less hepatotoxic than deoxycholic acid. To test this, lagodeoxycholic acid was synthesized, and its transport and metabolism were examined in the rat, rabbit, and hamster. The taurine conjugate of lagodeoxycholic acid was moderately well transported by the perfused rat ileum (Tmax = 2 mumol/min.kg). In rats and hamsters with biliary fistulas, the taurine conjugate of lagodeoxycholic acid was well transported by the liver with a Tmax greater than 20 mumol/min.kg; for the taurine conjugate of deoxycholic acid, doses infused at a rate greater than 2.5 mumol/min.kg are known to cause cholestasis and death. Hepatic biotransformation of lagodeoxycholic acid in the rabbit was limited to conjugation with glycine; in the hamster, lagodeoxycholic acid was conjugated with glycine or taurine; in addition, 7-hydroxylation occurred to a slight extent (approximately 10%). When lagodeoxycholic acid was instilled in the rabbit colon, it was absorbed as such although within hours it was progressively epimerized by bacteria to deoxycholic acid. When injected intravenously and allowed to circulate enterohepatically, lagodeoxycholic acid was largely epimerized to deoxycholic acid in 24 hours. Surgical creation of a distal ileostomy abolished epimerization in the rabbit, indicating that exposure to colonic bacterial enzymes was required for the epimerization. Lagodeoxycholic acid was administered for 3 weeks at a dose of 180 mumol/day (0.1% by weight of a chow diet; 2-4 times the endogenous bile acid synthesis rate); other groups received identical doses of deoxycholic acid (hamster) or cholyltaurine, a known precursor of deoxycholic acid (rabbit). After 3 weeks of lagodeoxycholic acid ingestion, liver test results and liver appearance were normal. The total bile acid pool expanded by 37% in the rabbit, lagodeoxycholic acid composing 10% of biliary bile acids. In the hamster, the total bile acid pool was expanded by 95%, lagodeoxycholic acid composing 22% of biliary bile acids; biliary lipid secretion remained unchanged. Tracer studies indicated that the fractional turnover rate of lagodeoxycholic acid was high (157%/day, rabbit; 116%/day, hamster) because of its rapid epimerization to deoxycholic acid in the colon. These studies indicate that lagodeoxycholic acid, the more hydrophilic epimer of deoxycholic acid, is transported and metabolized as other dihydroxy bile acids but is much less toxic than deoxycholic acid.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Analysis of coronary-sinus-occlusion pressure by iterating the convolution integral.

Intermittent coronary sinus occlusion (ICSO) has been shown to reduce infarct size and to improve regional myocardial function. Since the efficiency of the procedure is closely related to proper intervals of occlusion and release of the coronary sinus, the reactions of coronary haemodynamics to this intervention have to be investigated. Coronary sinus pressure measurements obtained from anaesthetized dogs are analysed for three different conditions: normal coronary perfusion, experimentally induced infarction of the LAD performed according to a specific time pattern. The mathematical modelling of the coronary sinus pressure (CSP) reaction upon ICSO is accomplished by a convolution integral, incorporating a memory function g(x). With the aid of a numerical technique this function is evaluated to reproduce the measured data as closely as possible. Since g(x) describes the CSP response in a universal manner it can serve subsequently to predict reactions to different occlusion and release patterns not actually measured. This use of a mathematical model may provide economical paths for future investigations by avoiding prohibitively large numbers of animal studies. For different physiological states; normal perfusion, infarction and reperfusion; we obtained different memory functions. These differences in g(x) are then shown to be precisely related to known characteristics of the normal and diseased state of the myocardium. Understanding the link between cardiovascular physiology and its mathematical representation is seen as an important aid in the selection of therapeutic interventions.

Animals↗
PubMed1985

[The importance of sports medicine field tests as a means of training control in northern endurance sports].

In endurance sports heart frequency at the aerobic threshold (2 mmol/l lactate) is recommended for extensive training and heart rate at the anaerobic threshold (4 mmol/l lactate) for intensive training. Both values could be estimated by means of exercise tests in the laboratory as well as in the field. However for training-recommendations only data estimated on a specific exercise procedure should be used.

Exercise Test↗
PubMed1984

[Effect of physical activity on coronary heart disease].

Regular exercise of moderate intensity is associated with reduced coronary atherosclerosis in primates on an atherogenic diet. In some animal species as well as in patients with coronary heart disease physical training results in improved myocardial perfusion. Aslo exercise seems to enhance fibrinolysis induced by venous occlusion. Obviously cardiac arrhythmias are not affected by exercise training. Regular physical activity affects some risk factors of coronary heart disease, e.g. by increasing plasma HDL-cholesterol concentration and decreasing triglyceride level. Exercise may favourable influence smoking, drinking and dietary habits and may produce some beneficial psychological changes. Preventive exercise should be of least moderate intensity three or at least two times a week.

Adult↗
PubMed1983

[Effect of acute beta 1 and beta 1/beta 2 receptor blockade on carbohydrate and lipid metabolism during exertion].

The influence of acute beta 1-receptor blockade using 50 mg metoprolol or beta 1/beta 2-blockade using 40 mg propranolol resulted in an equipotent reduction of cardiac frequency and systolic blood pressure without influencing diastolic pressure in ten healthy probands. There was no reduction of maximal bicycle ergometric exercise by either beta-receptor blocking agent. Serum glucose levels did not change during metoprolol in comparison to pre-test values. In contrast, propranolol resulted in a significant decrease of glucose levels during maximal exercise and 5 minutes after end of exercise. Plasma lactate was moderately lowered by both beta-receptor blockers after 20 min constant exercising when compared to pre-medication. Both substances reduced the insulin level in a comparable way during the exercise test. Serum triglyceride concentrations did not alter significantly during exercise tests. Serum free fatty acid levels showed a decreasing tendency until maximal exercise; however, there was no significant difference between values obtained with metoprolol or propranolol and drug-free pre-test.

Adrenergic beta-Antagonists↗
PubMed1980

[Investigations on the cardiovascular system at altitudes up to a height of 7,800 meters (author's transl)].

During a Karakorum expedition electrocardiographic investigations were performed. In the basic camp, 4,800 meters above sea level, ECG of test persons were registered in the resting state and after physical exercise. In addition, long-time recordings of heart rate reactions were made during various phases of mounting up to a height of about 7,800 meters. The ascent in extreme altitudes without an artificial oxygen supply did not cause electrocardiographical signs of myocardial hypoxia. Only supraventricular or ventricular ectopic beats could be detected in some instances. During continuous mounting, the heart rate rises to 120-140 beats per minute and reached 150 beats per minute during the last part up to the summit. Resting blood pressure measured in the basic camp over a period of 15 days showed no significant changes.

Adult↗
PubMed1979

[Aneurysm of Valsalva's sinus (author's transl)].

An aneurysm of Valsalva's sinus is one of the rarest malformations of the aortic root. The case of a non-ruptured aneurysm is reported and the possible pathogenic mechanisms of the congenital and the acquired forms of this aneurysm are discussed, as well as the clinical symptoms and the diagnostic procedures. Finally, the necessity of surgical treatment of the aneurysm is pointed out.

Adult↗
PubMed1978

[Diagnostic and clinical features of atrial myxoma (author's transl)].

The most common benign cardiac tumours are artial myxomas. Characteristically they may interfere with the normal functioning of atrioventricular valves or manifest themselves by embolism to cerebral or peripheral arteries or they may mimic systemic diseases. Hence, early diagnosis and immediate surgical treatment are important. A case of left atrial myxoma is reported and the various non-invasive and invasive diagnositc methods and their significance are outlined. If the angiocardiographic findings are questionable, the echocardiographic features are believed to be of greater reliability. Finally, the histopathology of atrial myxoma, the rate of tumour growth, as well as the possibility of postoperative reappearance of the myxoma are discussed.

Angiocardiography↗