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Biomedical subjects

H Weber

Publications and source records attributed to H Weber.

At least 361 records · Page 20Linked to original sources
PubMed1986

Percutaneous intracardiac direct-current shocks in dogs: arrhythmogenic potential and pathological changes.

In 12 dogs, a total of 65 direct-current (DC) shocks of 100-300 J were delivered through a standard USCI6F tripolar electrode catheter to selected sites in the heart. Severe arrhythmias were more frequent after electric shocks of high energy to the ventricles and AV-nodal or His-bundle region than after comparable shocks to the left or right atria. There was a direct relationship between the strength of the electric shocks, and the extent and severity of the injury. Application of 300 J shocks led to massive necrosis and damage to all components of the myocardium including the walls of small blood vessels. However, perforation of the atrial and ventricular walls or septum did not occur in any of the animals (mean follow-up period 97 days: range 8 to 167 days). Percutaneous DC shocks up to 250 J proved to be a safe technique for closed-chest ablation of conduction tissue in dogs. These might be of value for patients with arrhythmias requiring electrical ablation of accessory pathways or foci situated in various sites in the heart.

Animals↗
PubMed1986

Morphological changes in peripheral blood cells and skin in amiodarone-treated patients.

Amiodarone, used in the treatment of cardiac arrhythmia, may lead to severe discolouration of sun-exposed skin. The lysosomal storage of a lipid-like material has been shown to be the morphological substrate for this cutaneous hyperpigmentation. Examination of peripheral white blood cells of amiodarone-treated patients disclosed identical lysosomal structures indicating that amiodarone treatment leads to a more generalized lysosomal storage of lipids and of amiodarone and its metabolites.

Amiodarone↗
PubMed1986

MR imaging of the normal shoulder.

Magnetic resonance (MR) images of the shoulders of a healthy volunteer were obtained in axial, sagittal, and coronal orientations using a 0.5-T imaging system. Multiple high-resolution spin-echo images were generated using an off-center zoom technique and a specially designed surface coil. Several anatomic structures, including the rotator cuff, long biceps tendon, articular capsule, muscles, and bones, were visualized. The coronal and sagittal views were the most useful for demonstrating the rotator cuff. MR imaging has potential as a new non-invasive tool for the evaluation of the shoulder region.

Adult↗
PubMed1986

Corticotropin-releasing factor stimulates the release of adrenocorticotropin from domestic fowl pituitary cells.

The effect of synthetic ovine CRF on ACTH secretion of dispersed, domestic fowl pituitary cells was investigated. Cells preincubated for 2 h, 16 h, or after 48-h culture were incubated briefly with CRF (up to 4 h). ACTH was bioassayed using isolated rat adrenocortical cells; ACTH-(1-24) served as the standard for expressing the data. Results with 16-h preincubated cells were as follows: CRF induced ACTH secretion in a concentration-dependent manner: ED50 and maximal stimulatory concentrations were 1.0 nM and 5.0 nM, respectively. CRF (10 nM) induced significant ACTH secretion within 10 min of incubation; maximal secretion (370% over basal value) was attained at 2 h. Dexamethasone (DEX) inhibited basal and CRF-induced ACTH secretion in a concentration-dependent manner; half-maximal inhibitory and maximal inhibitory concentrations were approximately 10 nM and 1 microM, respectively. In addition, DEX (10 microM) acutely (within 2 h) inhibited maximal CRF-induced ACTH secretion by 46%. 8-Bromo-cAMP (1 mM) also induced ACTH secretion, and DEX inhibited this secretion with a potency equivalent to that for CRF-induced ACTH secretion. In contrast to the effect of CRF, high concentrations (100 nM) of ovine LHRH, TRH, and synthetic human pancreatic GH-releasing factor (1-32) failed to induce significant ACTH secretion, thus suggesting that the effect of CRF was peptide specific. Domestic fowl pituitary cells cultured for 48 h before treatment also responded to CRF but not to any greater extent than that of 16-h preincubated cells. In contrast to 16-h preincubated cells or 48-h cultured cells, 2-h preincubated cells had high basal values of ACTH secretion that may have partially diminished or masked the actions of CRF. These data suggest that 1) CRF is a potent and specific stimulator of ACTH secretion by domestic fowl pituitary cells and 2) 16-h preincubated cells or 48-h cultured cells are amenable for other in vitro investigations on the regulation of avian ACTH secretion.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1986

Genetic-dependent alterations in adrenal stress response and adrenocortical cell function of the domestic fowl (Gallus domesticus).

Strain-dependent differences in adrenocortical function were investigated in male White Leghorn domestic fowl. Adrenocortical function of Cornell K strain (K) (genetic control), autosomal dwarf strain (ADW), and sex-linked recessive dwarf strain (SLD) was evaluated in vivo by measuring plasma corticosterone and in vitro by measuring acute (2 hr) corticosterone production by enriched adrenocortical cell populations. Regardless of strain, there was an age-dependent decrease (27-57%) in plasma corticosterone from 1 to 12 weeks of age. However, there was a tendency for plasma corticosterone values of ADW and SLD to be, respectively, greater and less than that of K. In addition, at 12 weeks of age, plasma corticosterone responses of ADW and SLD to transient heat stress (50 degrees C, 30 min) were, respectively, 22.8% greater and 15.9% less than that of K. Strain differences in adrenal weight and relative adrenal weight (mg% body wt) were also apparent. At 12 weeks of age, adrenal weights of ADW and SLD were, respectively, 33 and 42% less than that of K, whereas relative adrenal weights were, respectively, 27.6% greater and 22.4% less than that of K. In addition there were strain-dependent differences in adrenocortical function at the cellular level. Although there were no consistent strain differences in basal and maximal corticosterone production by cells, there were strain differences in cellular sensitivity to ACTH and pregnenolone. On an equal cell concentration basis, the half-maximal steroidogenic concentrations (ED50 values or effective doses for 50% maximal effect) of ACTH for ADW and SLD adrenocortical cells were, respectively, 0.23 and 2.07 times the ED50 value for K cells. In addition, the ED50 value of pregnenolone for ADW cells was 0.46 times that for K and SLD cells. Since ED50 values are a measure of cellular sensitivity (the greater the ED50 value the lesser the cellular sensitivity), the order of sensitivity to ACTH was ADW greater than K greater than SLD and the order of sensitivity to pregnenolone was ADW greater than K = SLD. However, there were no strain differences in ED50 values of 8-bromo-cyclic AMP. These data suggest that strain differences in plasma corticosterone response to stress are, in part, due to differences in relative adrenal weight and differences in adrenocortical cell function.

Adrenal Cortex↗
PubMed1986

[Heart rate and arrhythmias in long-term ECG in patients with coronary disease and dilated cardiomyopathy with reference to left ventricular function].

Heart-rate (HR) and arrhythmias (AR) are influenced by the vegetative balance. This cannot be measured during daily life at present. Otherwise HR and AR can be detected with a high accuracy using the Holter-Method (HM). Therefore we investigated the relationship of HR, AR and left-ventricular function (LVF) in patients with coronary heart disease (CHD: 342 HM; normal LVF 33%, moderate reduced 33%, reduced 35%) and dilative cardiomyopathy (DCM: 225 HM, LVF normal 13%, moderate reduced 39%, reduced 48%), with special emphasis on the problem, whether tachycardia during chronic congestion will stimulate AR (AR due to an increased sympathic tone) or will suppress AR (overdrive suppression). Furthermore we evaluated, whether patients with a loss of the circadian pattern (CP) of HR or AR, who demonstrated an uniform high HR (due to the enhanced sympathic tone), were on higher risk of dying than other collectives. HM were analysed using the computer-supported "Multipass-Scanning" system. The decreasing LVF coincides with an increase in HR and a loss of HR-CP (i.e. dHR-day-night greater than or equal to 10 b.p.m.). The amount of the HR-CP depends on the mean HR during day in the manner of a direct relationship. The prevalence of premature ventricular ectopics (PVC) increases with decreasing LVF from 39 to 53% (CHD) and from 47 to 63%. A positive circadian pattern of the PVC exists in 60% of CHD and in 84% of DCM, which also decreases with the LVF to 54 vs. 52%. Independent from a CP in two thirds of the patients VA were stimulated and in one third suppressed with a worsening of the LVF. The phenomenon of an overdrive suppression of VA starts with a HR of 90 b.p.m. and higher. The 40% mortality in patients with an uniform (day and night) high HR (greater than 90 b.p.m.) was significantly higher than in other collectives (10%).

Adolescent↗
PubMed1986

[Value of long-term ECG in patients with syncope].

In a prospective study 24 hour long-term ECG (LT-ECG) recordings under ambulatory conditions were performed in 126 patients with syncopes (SY) of unknown origin. LT-ECG revealed arrhythmias (AR) in 57%, whereas 43% had inconspicuous findings. One patient developed a SY during LT-ECG without any evidence for arrhythmias. In 40% of these patients AR not detected previously by other methods were discovered. In 36% AR detected by LT-ECG had to be considered as precursors of syncopes (i.e. bradycardia less than 40 b.p.m., tachycardia greater than 160 b.p.m., AV-block II/II and III, or ventricular arrhythmias Lown IV). LT-ECG increased the information about the cause of syncope in 35%, whereas in 65% LT-ECG did not produce any further information. Consequently LT-ECG led in 56% to drug therapy, in 8% to PM-implantation. During a mean follow-up of 22 months 22% of patients developed again a syncopal attack and 4% died suddenly. Despite LT-ECG recording an ECG-registration during a typical syncopal attack for the confirmation or exclusion of an arrhythmogenic genesis of the SY is achieved only by chance. Nevertheless further informations with regard to precursing AR can be obtained, which may lead to therapeutic consequences in some patients. Therefore, LT-ECG has to be recommended as an essential, non-invasive procedure in patients with SY of unknown origin.

Adolescent↗
PubMed1986

Democratic expression of public opinion on animal experimentation.

In December 1985, a very clear majority of 70% of the Swiss population rejected the proposal of adding an article to the constitution which would have brought animal experimentation to a complete halt in the country. Evidently, the extreme views of antivivisectionist groups are only shared by a minority of the population. It was possible to achieve this very clear result although a strong aversion to animal experiments and a critical attitude toward biological research exist in Switzerland, as well as in other European countries. The favorable outcome of the vote is due to a broad campaign of frank and comprehensible information provided by the research community, and to the willingness of the scientists to accept ethical restrictions to their work. It has been deemed important in Switzerland to continue with the basic information on biological research and its implications, since an informed public is obviously less prone to the influence of extreme groups.

Animal Experimentation↗
PubMed1986

[Chylopericardium as a rare cause of a "large" heart shadow--2 case reports].

Two cases with the diagnosis of asymptomatic chylopericard were evaluated. One was a 20-year old girl who had been operated on for intrathoracic lymphangioma and chylopericardium that existed since birth, and who developed a chylothorax after the operation. The second case report concerns a 22-year old man who had been suffering from a posttraumatic asymptomatic chylopericardium for two years and who is being treated conservatively "Low-fat diet").

Adult↗
PubMed1985

Initial and residual toxicity following acute exposure of developing male rats to dibromochloropropane.

Male Fischer 344 rats were given a single, sc injection of 1,2-dibromo-3-chloropropane (DBCP) at 6 or 25 days of age. One group of treated animals was killed 1 to 3 days afterward to compare the dose and time relationships of the acute toxic response of neonatal and weanling male rats to DBCP and another group at approximate sexual maturity (approximately 120 days of age) to detect residual toxic effects resulting from acute exposure. The 6-day-old rats were more susceptible than the 25-day-old rats to the acute toxic effects of DBCP, as characterized by reduced 48-hr survival, renal dysfunction, and renal and hepatic necrosis over the dose range of 80 to 320 mg/kg. The lowest dose tested, 20 mg/kg, and all higher doses reduced subsequent body and gonadal weight gains, and caused hypospermatogenesis or seminiferous tubular atrophy in animals exposed at 6 days of age and killed at sexual maturity. Similar effects were observed in animals exposed at 25 days of age, except that doses of 160 mg/kg or greater were required to produce residual toxic effects. These data indicate enhanced susceptibility of neonatal male rats to the gonadotoxic effects of dibromochloropropane, including the possibility of apparent irreversible injury caused by acute exposure.

Aging↗
PubMed1985

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) in pregnant C57BL/6N mice: distribution to the embryo and excretion.

The distribution and excretion of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,3,7,8-tetrachlordibenzofuran (TCDF) were studied in pregnant C57BL/6N mice following an oral dose of 30 micrograms/kg 14C-TCDD and 800 micrograms/kg 14C-TCDF on gestation day 11. The distribution in maternal blood and liver and excretion in urine and feces was similar to that previously reported in males of the same strain. However, the rates of elimination were more rapid in pregnant females for both chemicals. This was more pronounced for TCDD than for TCDF. At all time points examined, the levels of radioactivity in the individual embryos were below 0.5% of the total TCDD dose and below 0.05% of the total TCDF dose. Assuming that all radioactive material found in embryos was unmetabolized compound, no more than 2.6 ng (8 pmoles) TCDD and 6.4 ng (21 pmoles) TCDF per g tissue were detected. In light of recent findings which strongly suggest a direct effect of TCDD and related compounds on embryonic palatal tissue, our data clearly support the potent teratogenic effect of TCDD and TCDF on the development of the secondary palate.

Animals↗