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Biomedical subjects

G Schmidt

Publications and source records attributed to G Schmidt.

At least 433 records · Page 24Linked to original sources
PubMed1984

Effects of fentanyl on a bradykinin-induced excitatory cardiac reflex in the anaesthetized rat.

A reflex increase in arterial blood pressure and heart rate was elicited by application of epicardial bradykinin (4 X 10(-8), 2 X 10(-7), 10(-6) g/ml) in pentobarbital-anaesthetized, thoracotomized rats. The influence of the opioid fentanyl and the tranquilizer diazepam on this increase was then investigated. When fentanyl (2.2 micrograms/(kg X min] was infused i.v. during periods of bradykinin application, a highly significant suppression of the excitatory reflex resulted. Epicardial bradykinin (10(-6) g/ml) induced an increase in mean arterial blood pressure of 25.3 +/- 3.5 mm Hg during the control period and of 6.8 +/- 1.4 mm Hg during fentanyl infusion. The corresponding changes in heart rate were +20.8 +/- 4.7 beats/min during the control period and +1.9 +/- 1.3 beats/min during fentanyl infusion. When cardioacceleration was induced by the carotid occlusion reflex, fentanyl antagonized this effect too. The effect of fentanyl was entirely neutralized by injecting naloxone (30 micrograms/kg i.v.) prior to application of the former. Diazepam had no influence on the bradykinin-induced reflex. The results support the view that morphinoceptors may modulate the excitatory cardiac reflex induced by epicardial application of the algesic bradykinin in the rat.

Anesthesia↗
PubMed1984

[Cardiac arrhythmias and their clinical significance in mitral valve prolapse].

Among 160 patients with mitral-valve prolapse but no other illness there were 118 with cardiac arrhythmias. 30 had frequent or multifocal ventricular premature systoles, 21 had coupled ventricular extrasystoles, and seven had ventricular tachycardia. In six patients the prematurity index was under 1. Supraventricular premature systoles were registered in 56 patients, with seven each having paroxysmal atrial tachycardia and paroxysmal atrial flutter or fibrillation. Ventricular arrhythmias were significantly more frequent in late-systolic prolapse and with positive auscultation findings (systolic click or systolic murmur). Long-term ECG monitoring was more valuable than an exercise ECG. About half the patients with frequent arrhythmias had palpitations and rapid heart action. Coupled ventricular premature systoles and ventricular tachycardias, as well as R-on-T were relatively rare; our findings thus tend to suggest a relatively favourable prognosis for these arrhythmias.

Adolescent↗
PubMed1984

Ethanol induces an increase of harman in the brain and urine of rats.

Harman occurs in rat brain, with the highest concentration in the cerebellum and the lowest in the striatum. 2 g/kg ethanol were ineffective with respect to the concentration of harman in the brain whereas 5 g/kg ethanol caused a time-dependent increase in the cerebral cortex as well as the cerebellum. A toxic dose (8 g/kg) of ethanol elicited no change of harman in the brain 3 h following the application. The rise in the harman concentration in the brain did not correlate with the increase of acetaldehyde in the blood after treatment with ethanol suggesting that several mechanisms are involved in the changes of the levels of harman. In subchronic experiments rats were treated with ethanol over a period of 5 or 6 days. Harman increased in the brain whereby the effect seemed to be more pronounced in the cerebellum than in the cerebral cortex. The concentration tended to increase over time and reached control levels again during withdrawal. The time course of the excretion of harman into the urine was similar to that of the brain in that it increased continuously during the period of ethanol treatment and reached control levels again during withdrawal.

Acetaldehyde↗
PubMed1984

Changes in sex differences in sexual behavior: a replication of a study on West German students (1966-1981).

In 1966, at the start of the student movement and the sexual liberalization process, we studied the sexual behavior and attitudes of 3,666 male and female students from 12 West German universities by mailed questionnaires. In 1981 we replicated this study with 1,922 students from 13 universities (10 the same as 1966, 3 founded after 1966). In both studies the students were selected at random. Results of these comparative studies are presented with a view to the changes in sex differences. Sex differences in masturbation behavior have considerably decreased since 1966; masturbation is nonetheless still the form of sexual behavior with the most striking differences between the sexes. The sex differences in coital behavior are now reversed, female students being earlier and more active than males. As regards the tendency to change partners or for sexual relations outside a steady relationship, the differences between men and women have disappeared. In their attitudes to sexuality, female students in 1981 are somewhat more liberal than their male counterparts, whereas hardly any difference could be found in 1966. These changes in sex differences are observed in all subsamples, i.e., in young and old, in strictly religious and nonreligious students, and in students from both upper- and lower-class backgrounds (educational level of parents).

Adult↗
PubMed1984

Studies on the mechanisms of secondary pause after high rate atrial pacing.

Atrial pacing up to 400 beats per minute (bpm) was performed in 20 open chest dogs. Measurements were made on the first five return cycles. Instances with the first cycle shorter than the basic cycle length were excluded. Secondary pauses (SP) were frequently observed at pacing rates equal to or faster than 280 bpm. Intravenous application of propranolol and atropine did not diminish SP, nor did bilateral vagotomy. Additional subthreshold stimuli, as well as stimulation with electrodes with large interpolar distance influenced neither the length of sinus node recovery time (SNRT) nor the SP phenomenon. Simultaneous pacing of the right atrium and right ventricle had no significant effects on SNRT and SP. Pacemaker shifts occurring frequently after high rate pacing were not necessarily accompanied by SP. The velocity of activation spread over the sinoatrial region was significantly slower (46.9 +/- 7.3 cm/s) in cases with SP than in those with primary pauses (PP) (72.5 +/- 8.1 cm/s). It was concluded that high rate induced SP was a feature indicating suppression of sinoatrial conduction.

Animals↗
PubMed1984

Gastroduodenal metastases--an unusual initial manifestation of bronchogenic carcinoma.

A 75-year-old woman with multiple polypoid lesions in the gastroduodenum , and one large gastric ulceration all representing large-cell type carcinoma is described. Radiologic and fiberbronchoscopic , together with other clinical findings suggested bronchogenic carcinoma as the primary tumor. Metastatic gastric involvement is an uncommon feature of primary bronchogenic carcinoma, rarely attaining clinical significance. In our patient, gastric symptoms represented the initial clinical manifestation of hitherto undetected bronchogenic cancer disease.

Aged↗
PubMed1984

Effects of propranolol and epinephrine on density of capillaries in rat heart.

The influence of propranolol and epinephrine on the time course of capillary plasma filling and the maximal obtainable capillary density was studied in the hearts of anesthetized rats. The blood plasma was labeled in vivo with macromolecule-coupled fluorochromes (lissamine-rhodamine B 200 and fluorescein isothiocyanate) for different periods of time and the density of marked capillaries determined in frozen sections of the heart. In the propranolol-treated (1.0 mg/kg) rats complete filling was observed after 40 s (controls: 10 s). When epinephrine (5.0 micrograms X kg-1 X min-1) was infused, plasma filling was completed within 5 s. Maximal capillary densities were higher in the drug-treated groups than in the control group (controls 3,530 capillaries/mm2; propranolol 3,890 capillaries/mm2; epinephrine 3,930 capillaries/mm2, subepicardium). This increase was induced by a reduction in mean diameter of muscular fibers due to a higher distension of the left ventricular wall in the drug-treated rats. It is concluded that changes in plasma transit times and in intercapillary distances due to fiber lengthening were induced by high doses of propranolol or epinephrine.

Animals↗
PubMed1984

Method for measurement of heart rate in awake, noninstrumented small mammals.

A method is described that enables the researcher to determine the heart rate in awake, noninstrumented small animals by recording the electrocardiogram (ECG) via the paws. Single animals are placed in a cage that has metal plates built into its floor. Through switches any two plates can be connected with an ECG recorder whenever contact with at least one front and one hind paw is made. The heart rate is then determined by measuring the number of R waves per unit of time. In rats of 140 and 300 g body wt mean resting heart rates of 384 +/- 10 and 320 +/- 4 beats/min, respectively, have been measured with this method.

Animals↗
PubMed1984

[The effect of amiodarone on thyroid gland function].

Plasma concentrations of T4, FT4, T3, rT3 and TBG, as well as of TSH before and after stimulation with TRH were studied in 25 patients, who had been treated with amiodarone for up to nine years. At the beginning of therapy, all the parameters mentioned above were found to be in the normal range in all patients. After two months of therapy, T4 had increased from 100 nmol/l +/- 24 nmol/l to 155 nmol/l +/- 32 nmol/l (p less than 0.01), and FT4 from 22 pmol/l +/- 10.5 pmol/l to 32 pmol/l +/- 8 pmol/l (p less than 0.01). T3 had decreased to the lower normal range (n.s.). TBG showed no significant changes. The TRH-tests had been normal in the beginning, but they remained positive in only 20% of the cases. At the end of the study, rT3 exceeded the normal range in all 25 patients. Two patients developed definite hyperthyroidism with elevations of T3 up to 4.7 nmol/l and 7.5 nmol/l, respectively. In one of them, we decided to discontinue amiodarone. Testing of thyroid function under antithyroid drug therapy revealed a hyperfunctioning autonomous adenoma, which was successfully eliminated by radioactive iodine therapy. In the other patient, it was not possible to withdraw amiodarone, so we initiated long-term treatment with antithyroid drugs. Our data support the assumption that amiodarone causes an impairment of the peripheral conversion of T4 to T3. As a result, one finds elevated serum concentrations of T4, which, in combination with the mainly negative TRH-test, must not be interpreted as proof of a hyperthyroid metabolic state being present. Hyperthyroidism is confirmed only if serum concentrations of T3 are also elevated.

Adolescent↗