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Biomedical subjects

H Schön

Publications and source records attributed to H Schön.

At least 19 recordsLinked to original sources
PubMed1992

Behavioral and neurochemical indices of barrel cortex-basal ganglia interaction.

Previous experiments from our laboratory have shown a wide variety of time-dependent lateralized changes in behavior and nigrostriatal function following unilateral manipulation of the mystacial vibrissae of rats. The present experiment investigated the effects of unilateral radiofrequency lesion of the cortical vibrissae representation (the barrel fields) in light of these results. We measured lateralized changes in behavior as well as tissue monoamines in neostriatum and substantia nigra, between 1 and 16 days post-lesion. Short-term asymmetries in exploratory behavior (thigmotactic scanning) and neostriatal serotonin metabolism that lasted up to day 6 were seen. In substantia nigra, time-related asymmetries in dopamine concentrations were found with higher ipsilateral values on day 3 and higher contralateral values on day 6. After day 6, the animals had recovered from these acute effects and thereafter, neostriatal dopamine metabolism became asymmetrical. Also during this time, they showed a directional bias in spontaneous and apomorphine-induced turning. Finally, neostriatal serotonin was bilaterally elevated on day 16. These results parallel some of the effects previously seen following unilateral removal of the vibrissae, indicating that the barrel cortex is a critical link in the functional interaction between the vibrissae and basal ganglia.

Animals↗
PubMed1989

Peroxisomal oxidation of pipecolic acid in the rat.

Postnuclear fractions from rat liver and kidney oxidize L-pipecolic acid, a by-product of lysine catabolism, in a hydrogen peroxide-producing reaction. This pipecolate oxidase2) activity is enhanced in preparations from animals treated with clofibrate and thyroxine, substances known to act as peroxisome proliferators and inducers of the peroxisomal fatty acid beta-oxidation. The enzymatic activity co-purified with the peroxisomal marker fatty acyl-CoA oxidase2) rather than with the mitochondrial marker glycerol-3-phosphate dehydrogenase2). Thus the degradation of L-pipecolic acid may start in the rat with a peroxisomal oxidase comparable to other hydrogen peroxide-producing oxidases found in peroxisomes. These findings provide indirect evidence that the marked hyperpipecolinaemia described in a group of human genetic disorders connected with peroxisomal defects such as Zellweger syndrome might be due to the absence of peroxisomal L-pipecolate oxidase.

Animals↗
PubMed1988

[Therapy resistance of amiodarone-induced hyperthyroidism].

The case of a 77-year-old patient who suffered from clinically severe and persistent hyperthyroidism induced by amiodarone is described. Amiodarone-associated hyperthyroidism is a rare (1-5%) but potentially severe complication. Its treatment presents a serious problem. The newer forms of treatment of this specific type of hyperthyroidism with prednisone and perchlorate are described. Under a combined therapy with thionamide drugs, prednisone and perchlorate euthyroidism could be achieved only after months. We propose a simple diagnostic procedure during amiodarone therapy based on the determination of basal ultrasensitive TSH enabling early recognition of amiodarone-associated hyperthyroidism. Thus, with well defined cardiac criteria for therapy with amiodarone as well as early assessment of thyroid dysfunction the incidence of this potentially severe complication can be reduced.

Aged↗
PubMed1986

[Traumatic myocardial infarct. Report of 3 cases].

Three patients aged 52, 22 and 29 years, without known previous heart disease, sustained acute myocardial infarction due to blunt chest trauma. A 52-year-old man without a history of heart disease sustained an acute non-transmural lateral myocardial infarction following blunt chest trauma during a sledging party. No coronary arteriography was performed. The clinical course during follow-up of 3 1/2 years was uncomplicated. A 22-year-old, previously asymptomatic man developed acute transmural anteroseptal infarction after a motor-cycle accident. Seven days later he died suddenly after an uncomplicated initial course. The autopsy demonstrated a complete rupture of the proximal left anterior descending artery with periarterial hemorrhage, compression of this artery by the hemorrhage and luminal thrombosis distal to the rupture. No sign of preexisting atherosclerotic coronary disease was found. A 29-year-old man admitted to the hospital after blunt chest trauma during a football game developed an acute transmural inferior infarction with an uncomplicated clinical course. Seven months later coronary arteriography demonstrated a 40% obstructive lesion of the right coronary artery, compatible with thrombosis and subsequent recanalization.

Accidents, Traffic↗
PubMed1984

[Noninvasive first-pass study of the heart with the short-lived radionuclide gold 195m].

The new shortlived radionuclide Aurum 195 m (T1/2: 30.5 sec) has been used for 1,596 first-pass examinations of 792 patients. During first-pass the same maximum count rates of an average of 300,000 cts/sec and after background subtraction the same enddiastolic counts over the left ventricle averaging 10,000 cts/sec can be achieved as with the previously used Tc-99 m pertechnetate injections. The short half-life and fast regeneration of Au-195 m within 3 minutes allow repeated, subsequent injections with significant reduction in radiation exposure. Half of the studies were done at rest and exercise, one third in two oblique projections, RAO and LAO. Examinations in two projections improve the information facilitating the localization of ischemic or infarcted LV-regions particularly with respect of septal and/or lateral extension. Strictly lateral dysfunction may sometimes be only recognizable in the second LAO-projection. The RAO-view best discriminates the extension along the anterior and infero-posterior wall.

Evaluation Studies as Topic↗
PubMed1983

Toxicological evaluation of cyclosporin A.

Toxicological studies in a variety of different animal species have shown that cyclosporin A (CS-A) is a unique immunosuppressant, since it does not cause myelotoxic, teratogenic, mutagenic, or carcinogenic effects. This is undoubtedly due to the fact CS-A produces its immunosuppressive effects by a specific action on T lymphocytes rather than by a cytotoxic mechanism. The incidence of acute inflammatory lesions was also not significantly higher in treated animals than in controls. Clear-cut organ toxicity only occurred in rats and cynomolgus monkeys, where at high doses nephro- and hepatotoxicity were observed.

Animals↗
PubMed1982

Assessment of regurgitant fraction and right and left ventricular function at rest and during exercise: a new technique for determination of right ventricular stroke counts from gated equilibrium blood pool studies.

Calculation of accurate stroke count ratios for the assessment of valvular regurgitation from equilibrium blood pool images has been difficult and did not permit computation of regurgitant fractions (RF) because of contamination of right ventricular (RV) stroke counts by right atrial activity. We describe a new approach to correct for this contamination by subtracting one half of the right atrial counts from the RV counts, assuming that in the standard or "modified" left anterior oblique projection commonly used about one half of the right atrial activity is superimposed to the RV. This new method was tested in 20 patients without valvular disease or shunts. Left ventricular (LV) to RV stroke count ratio approached unity (1.01 +/- 0.14). RV ejection fractions (EF) derived by this technique agreed well with those obtained by gated first-pass studies recorded in the right anterior oblique projection. In 9 normals and 17 patients with moderate severe or severe aortic (12 patients or mitral (7 patients) regurgitation, LVEF, RVEF, and RF were determined at rest and maximum exercise. In patients at rest, LVEF (56.0 +/- 6.4%) and RVEF (49.0 +/- 7.3%) did not differ significantly from LVEF (59.6 +/- 4.2%) and RVEF (52.5 +/- 6.4%) in normals. The calculated RF was negligible in normals (1.9 +/- 8.6%), but averaged 51.8 +/- 9.8% in patients with valvular disease. During exercise, LVEF fell significantly (p less than 0.001) to 44.1 +/- 7.2% in patients but increased to 70.5 +/- 3.8% in normals. RVEF increased in aortic regurgitation to 64.5 +/- 9.8% (NS to normals) but fell in mitral regurgitation to 36.6 +/- 5.9% (p greater than 0.001). In both patient subsets RF decreased with exercise to 25.4 +/- 15.0% in aortic and 39.1 +/- 12.7% in mitral regurgitation. The results indicate that this new approach permits assessment of RVEF and RF from gated equilibrium blood pool studies and is suitable to evaluate the hemodynamic response to physiologic and therapeutic interventions in patients with valvular regurgitation.

Adult↗
PubMed1982

Phase analysis of radionuclide ventriculograms for the detection of coronary artery disease.

The value of phase analysis of multiple gated acquisition blood pool images for identifying wall motion abnormalities due to stress-induced ischemia was examined. Myocardial segments with an abnormal phase, i.e., delayed onset of wall motion, were localized on a phase distribution image of the LV and the synchrony of LV systolic wall motion was assessed from histograms of the LV phase distribution, i.e., the standard deviation (SD) from the mean of this peak, which was defined as SDP, its upper limits of normal at rest and exercise were established in seven normals as the mean +2 SD and were 12 degrees at rest and 10 degrees at maximum exercise. Of the 56 patients, 37 had coronary artery disease (CAD), 11 had valvular disease but normal coronary arteries, and eight had normal coronary arteries, no valvular disease, but had either cardiomyopathy or typical angina. In the CAD patients, SDP was abnormal in 95% during exercise while only 86% had an abnormal ejection fraction (EF) response and/Or exercise-induced wall motion abnormalities by visual interpretation. By contrast, in the 11 valvular heart disease patients, SDP was abnormal in only two despite exercise-induced wall motion abnormalities in five and an abnormal EF response in all 11. Thus, although an abnormal EF response to exercise is a sensitive indicator of cardiac disease, it is, however, like exercise-induced wall motion abnormalities, not specific for CAD. By contrast, phase analysis not only permitted separation of wall motion abnormalities induced by ischemia from those associated with valvular disease, but was also an objective, highly sensitive, and specific indicator of regional myocardial ischemia.

Adolescent↗
PubMed1981

Toxicological evaluation of fluproquazone.

The toxicological characteristics of 4-(p-fluorophenyl-1-isopropyl-7-methyl-2-(1H)quinazolinone (fluproquazone), an analgesic with distinct antiinflammatory properties, were evaluated in acute and chronic toxicity studies as well as in reproduction toxicity, carcinogenicity and mutagenicity studies. The following overall results were obtained: The acute oral toxicity in mice, rats, and rabbits is of low order. In the chronic oral studies fluproquazone was generally well tolerated when given to rats and dogs for 13 weeks, to dogs and monkeys for 52 weeks, to mice for 78 weeks and to rats for 104 weeks. In particular, there was no indication of gastrointestinal irritations or lesions in any of these studies. The results of the studies in dogs and rats showed the major target organs for the toxicity of fluproquazone to be the liver and kidney, where mild, reversible changes were observed. These findings were considerably less severe than those found with several other antiphlogistic-analgesic compounds. In the reproduction toxicity studies, the only drug-related effects seen in experiments on female fertility or peri- and postnatal development in rats were a prolongation of pregnancy and an impairment of delivery leading to an increased perinatal mortality. These findings may be related to an inhibition of prostaglandin synthesis by fluproquazone. Similar effects are known to occur after administration of other inhibitors of prostaglandin synthesis. The oral teratological studies in rats and rabbits did not reveal any embryolethal or teratogenic effects. The drug had no mutagenic effects in either the micronucleus test and the dominant-lethal test using mice, or in the Ames-Test using Salmonella typhimurium. The carcinogenicity studies showed that fluproquazone has no carcinogenic potential in rats and mice.

Animals↗
PubMed1978

Collection of control data from teratological experiments on mice, rats, and rabbits. A group study.

A joint study was undertaken in the laboratories of five pharmaceutical companies to evaluate accumulated data on the progeny of mice, rats and rabbits of various strains or breeds. The recorded morphological deviations from normal were classified according to the time of their occurrence during embryonic and foetal development, and three categories were differentiated. Comparison of the data from the various laboratories in general revealed similar results, and the variations observed are presumed to be due to differences in experimental conditions.

Animals↗