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Biomedical subjects

H Weber

Publications and source records attributed to H Weber.

At least 451 records · Page 25Linked to original sources
PubMed1982

A new method for the determination of the mechanical properties of the vitreous.

In order to determine the mechanical properties of the vitreous which are characteristic for the extraction of foreign bodies, an oscillatory method was devised. The mechanical properties are described by a spring constant--relevant for the rubber elastic behaviour--and a friction constant characterizing the dissipative interaction inside the vitreous. The appropriateness of the data is demonstrated by the capability to predict the distance-time behaviour in strong, pulsed magnetic fields of ferromagnetic foreign bodies implanted into the vitreous of pig eyes.

Animals↗
PubMed1982

Effect of levomepromazine on EEG and on clinical side effects after lumbar myelography with metrizamide.

In patients with lumbago-sciatica levomepromazine is a potent supplement to analgetics in pain treatment. The hypothesis that neuroleptics increase the risk of epileptic seizures after metrizamide myelography was not confirmed in a series of 77 patients, 26 with and 51 without levomepromazine medication, before and after lumbar metrizamide myelography. No differences existed between the groups with regard to the appearance of EEG abnormalities such as slow waves or spikes. Mild side effects were more frequent in the levomepromazine group, except nausea and vomiting. Lumbar metrizamide epidurography in 30 patients did not cause any abnormal EEG.

Drug Interactions↗
PubMed1982

Fate of 2,3,7,8-tetrachlorodibenzo-p-dioxin metabolites from dogs in rats.

1. Metabolites of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were extracted from the bile of TCDD-treated dogs and administered by gavage to bile-duct-cannulated rats and also to an intact rat. 2. Radioactivity of the TCDD metabolites was rapidly cleared from the body of the rats, indicating that bioaccumulation of these compounds does not occur. 3. Biliary excretion was the most important route of elimination in the cannulated rats and amounted to greater than 30% of the administered dose within 24h. TCDD metabolites were also eliminated to a minor extent by the kidneys. The combined recovery of radioactivity in faeces, bile and urine after 24h accounted for greater than 85% of the dose. 4. The intact animal exhibited a somewhat different kinetic behaviour in that only 13% dose was excreted in faeces and urine after 24h, which indicates enterohepatic circulation. The administered radioactivity was completely recovered after 72h. 5. Results from the present experiments indicate that metabolism of TCDD is the rate-limiting step in elimination of TCDD from the liver. Interspecies variability in the toxicity of TCDD may in part be attributable to different rates at which the species metabolize and excrete TCDD.

Animals↗
PubMed1982

Meeting requirements for primate animals in drug development.

An overview on the numbers and species of monkeys used in the area of drug development in the USA and Europe during the years 1975 to 1981 is presented. A marked decline of 25% to 40% in the numbers used is due to a more critical use of the various species, besides a shortage of available animals. However, because for certain experiments some primate species are the animals of choice, there is a limit to further reductions. For future supplies, intensive breeding units, semifree-range colonies, and game farming may be considered. Using the revenue of exported animals, a financial contribution to the conservation of feral animals in the countries of origin could be made.

Animal Husbandry↗
PubMed1982

[Experimental model for determination of an "in vivo" area at risk accounting for the quantity and distribution of collateral flow (author's transl)].

To determine the influence of interventions on infarct size numerous studies have attempted a comparison between treatment and control groups. This has been complicated by the great variability in the quantity of necrosis due to the differences in coronary bed size and collateral flow. An experimental model is presented in which it is possible to determine an "area at risk of infarction" at several time points during the evolution of the infarct. This model allows to estimate infarct size that may be expected under the present conditions, prior to interventions, early, in vivo and in the same experiment. It is possible to quantitate topographically changes in collateral flow and to investigate the effect of intervention in the same experiment. We found a correlation of life-threatening arrhythmias including ventricular fibrillation with the size of the "myocardium at risk of infarction" and with the size of the infarcts measured post mortem. Several beneficial interventions were studied.

Animals↗
PubMed1982

[Diagnosis and therapy of carotid sinus syndrome (author's transl)].

We investigated 76 patients with carotid sinus syndrome followed over a time period of 12-40 months (mean 24 months). In 27 patients long-term ECG were recorded over 24 hours continuously. Carotid Doppler sonography was performed in all patients. 14 patients were studied electrophysiologically. The long-term ECG examinations in patients with carotid sinus syndrome showed a significant tendency to nocturnal bradycardia, and normal heart frequency during the day. In 41% of patients extracranial obstruction of internal carotid arteries could be demonstrated. During carotid sinus massage was a significant increase of the AH time, but there was no significant changes of the HV time. 12 out of 14 patients (86%) developed an AV-block during carotid sinus massage and atrial pacing. In 31 patients pacemakers were implanted. The indication for pacemaker implantation was the clinical symptom of syncope. These patients were observed over a period of 15-40 months (mean 24 months). 15 patients were free of symptoms after the pacemaker implantation, whereas 8 patients complained of dizziness and 4 patients experienced TIA's. 45 patients without pacemaker implantation were observed over a time period of 12-24 months. 30 patients were followed over 12 months. 16 patients were free of symptoms, 14 complained of dizziness. There was no syncopy in this group and no patients died during the observation period. In patients with cardio inhibitory carotid sinus syndrome and syncopy, pacemaker implantation is the therapy of choice. In asymptomatic patients or patients with occasional dizziness pacemaker is not indicated.

Aged↗
PubMed1982

[Computer assisted long-term ECG analysis: method and clinical importance (author's transl)].

The basic principle of computer assisted analysis of Holter recordings is to store the whole ECG after data reduction and AD conversion in digitized form on random access medium like magnetic disks. In "Multipass Scanning" the linear segmentation techniques leads to highly reproducible ECG-data, which were analysed during multiple passes under continuous operator control. The field of clinical applications of such a highly sophisticated method reaches from supraventricular over ventricular to symptomatic arrhythmias. In combination with ECG-telefon-telemetry computer assisted LT-ECG analysis could be used in more than 75% of the patients successfully. The clinical expectations during routine could be fulfilled in more than 75%. Commonly a detailed numerical or graphical description of clinical relevant arrhythmias were necessary in the demand of the routine. So computer assisted LT-ECG analysis is not only a tool for research, but also valuable in the clinical routine.

Arrhythmia, Sinus↗
PubMed1982

Simultaneous perfusion of [4-14C]oestriol and [6,9-3H2]oestriol 16 alpha-monoglucuronide through the isolated rat liver. I. Qualitative aspects.

Equimolar concentrations of [4-14C]oestriol and [6,9-3H]oestriol 16 alpha-monoglucuronide were simultaneously perfused through isolated rat livers. Oestriol was hydroxylated to 2-hydroxyoestriol and 6 xi-hydroxyoestriol; 2-hydroxyoestriol was further methylated to 2-methoxyoestriol. Oxidoreduction of oestriol led to the formation of 16 alpha-hydroxyoestrone, 16-0xooestradio-17 beta and 16-epioestriol. In addition, two dehydroxylation products, namely oestrone and oestradiol-17 beta were found. The metabolites formed from oestriol were partly conjugated to monoglucuronides, monosulphates and sulphoglucuronides. About 80% of the oestriol perfused was hydroxylated at C-atom 2. Most of the 2-hydroxyoestriol formed was either methylated (about 37%) or sulphated (about 55%). Only small amounts (less than 2%) of the catecholoestrogens formed were methylated as well as sulphated. The 2-hydroxyoestriol monosulphates accumulated in the liver. After their conjugation with glucuronic acid, the double conjugates formed were immediately excreted into the bile. In fact, 2-hydroxyoestriol 16 alpha-monoglucuronide 2(3?)-monosulphate comprised by far the main biliary metabolite of [4-14C]oestriol, followed by oestriol 16 alpha-monoglucuronide and 2-methoxyoestriol 16 alpha-monoglucuronide. No triated sulphoglucuronides were detected, thus indicating that the monosulphates are the immediate precursors of the double conjugates. [6,9-3H2]Oestriol 16 alpha-monoglucuronide was metabolised only to a small extent. After its uptake into the liver more than 90% of this conjugate was secreted unchanged into the bile. The remaining part was hydrolysed; the oestriol liberated followed the same metabolic reactions as those found for [4-14C]oestriol. This indicates that the 16 alpha-glucuronide of oestriol is not metabolised to any appreciable extent.

Animals↗
PubMed1982

Simultaneous perfusion of [4-14C]oestriol and [6,9-3H2]oestriol 16 alpha-monoglucuronide through the isolated rat liver. II. Kinetic aspects.

The uptake of [4-14C]oestriol by the isolated perfused rat liver is 3.8 times faster as compared to that of simultaneously perfused [6,9-3H2]oestriol 16 alpha-monoglucuronide. During perfusion the concentration of both radioactive oestrogens decreased exponentially in perfusion medium (apparent kel: 0.061 min-1 and 0.016 min-1, respectively). [6,9-3H2]Oestriol 16 alpha-monoglucuronide was metabolized only to a small extent; more than 92% was secreted unchanged into the bile where it was highly concentrated (1800 nmol/g). In contrast [4-14C]oestriol was extensively metabolized; it was mainly hydroxylated at C-atom 2, leading to a rapid increase in the concentration of 2-hydroxyoestriol in the perfused medium. This metabolite was quickly taken up by the liver during recirculation and subsequently either methylated or sulphated. 2-Hydroxyoestriol monosulphate was glucuronated to 2-hydroxyoestriol 16 alpha-monoglucuronide 3-sulphate, which was rapidly excreted into the bile. No double conjugate was formed when [6,9-3H2]oestriol 16 alpha-monoglucuronide was perfused; this is additional evidence for the correctness of the assumption that monoglucuronides cannot serve as precursors of sulphoglucuronides.

Animals↗
PubMed1982

[Follow-up studies in 64 patients with WPW syndrome after electrostimulation].

In 65 out of 79 patients with WPW syndrome who had extensive electrostimulation studies, a follow-up evaluation (mean follow-up period 2.5 years) was performed. The patients were divided into 2 groups: Group 1: No therapy or therapy only during tachycardia. Group 2: Continuous oral drug therapy. There was no difference of antegrade and retrograde refractory periods, but there was a significant difference in the initiation of tachycardias. In group 1, the typical reentry tachycardia using the AV node antegradely and the accessory pathway retrogradely was predominant, while in group 2, complex arrhythmias (atrial fibrillation + reentry tachycardia, tachycardias using the accessory pathway in both directions, reentry tachycardia + AV-nodal tachycardia, isolated atrial fibrillation) during electrostimulation could be induced. all except 1 patient in whom no tachycardia could be initiated were in group 1 (statistically significant difference). Thus the type of tachycardia which can be initiated during electrostimulation is a better predictor for the condition in the follow-up period than the refractory period. As concomitant disease there were 4 cases with Ebstein disease (2 had additional mitral valve prolapse syndrome) and 3 cases with mitral valve prolapse syndrome. 3 of the 4 patients with Ebstein disease were in group 2. 1 of the 64 patients died during the follow-up period suddenly, but the cause of death is not known and possibly due to medical therapy. The mortality in a non-selected group of patients with WPW syndrome seems to be very low.

Adolescent↗
PubMed1982

[Drug therapy of neurogenic bladder with the alpha-receptor blocker phenoxybenzamine].

A report is given on the results of therapy with the alpha-adrenolytic phenoxybenzamine in 36 patients in a rehabilitation centre for paraplegics. The sole indication for using the preparation was neurogenously disturbed micturition with large quantities of residual urine. The best therapeutic results--i.e. reduction of residual urine to 60 ml or less--were achieved in patients with lesions of the lower motoric neuron (15 patients) and the upper motoric neuron in the region L2-S2 (1 patient). The results in cases of lesion in the region Th10-L2 (3 patients) were so bad that the application of the preparation cannot be recommended in such cases. In cases of paralysis of the thoracic cord and the cervical part of the medulla (14 patients) 50% of the results were good and 35% were bad.

Adolescent↗