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Biomedical subjects

H Fischer

Publications and source records attributed to H Fischer.

At least 325 records · Page 18Linked to original sources
PubMed1988

[Percutaneous transhepatic lysis of gallstones using methyl tert-butyl ether. Report on 15 patients].

In 15 patients (13 women and two men) with cholesterol stones in the gall-bladder a special (Thistle) catheter was introduced into the gall-bladder under local anaesthesia by percutaneous transhepatic puncture. Methyl-tert-butyl ether, 2-15 ml, was injected via the catheter and removed again after 2 min. The number of stones per gall-bladder averaged 6.3 (1-20), size of stones 1.7 cm (0.5-2.8 cm), and duration of treatment 11.9 h (5-24 h). The stones dissolved in 13 patients (87%). In three patients stone débris remained: in one it was ultimately sucked out after reduction of the amount of débris with an EDTA-containing solution. The side effects of treatment--nausea and vomiting--were minor. In one patient there was a leak of bile from the gall-bladder after the procedure; a cholecystectomy was uneventfully performed. Another patient developed haemobilia which responded to conservative treatment. MTBE treatment has thus proved to be a successful and cheap method, low in side effects, in the treatment of patients with gall-stones.

Adult↗
PubMed1988

A novel biologically active selenooorganic compound--VII. Biotransformation of ebselen in perfused rat liver.

Ebselen (PZ 51) is a selenoorganic compound with antioxidant and antiinflammatory properties, and its metabolism was studied in isolated perfused rat liver (hemoglobin-free, open system). 75Se-labelled ebselen was taken up into liver cells and radioactivity was excreted into bile. Biliary excretion of 75Se-compounds reached maximal values of 4 nmol/min per g wet wt. HPLC analysis of bile and effluent perfusate as well as identification of separated metabolites by mass spectrometry were carried out. The biliary metabolites were (a) an interesting novel Se-glucuronide, 2-glucuronylselenobenzanilide, (metabolite IV), as the major metabolite, and (b) an O-glucuronide, N-(4'-glucuronyloxyphenyl)-2-methylselenobenzanilide (metabolite III). The major effluent perfusate metabolites were Se-methylated derivatives (metabolites I and II). There was no evidence for sulfated metabolites. The selenodisulfide with glutathione, S-(2-phenyl-carbamoyl-phenylselenyl)-glutathione, was not detected, probably because of low steady-state concentrations and/or its biochemical lability. The selenium in ebselen is not bioavailable (e.g. for the synthesis of glutathione peroxidase), in contrast to selenite, for example, thus explaining the very low ebselen toxicity. However, the enzymatic steps in Se-methylation could be similar to those in the metabolism of selenite which include hydrogen selenide methylation. Se-glucuronides constitute a novel category of compounds in addition to the O-, N-, C- and S-glucuronide classes known in biology.

Animals↗
PubMed1988

A new steady-state imaging sequence for simultaneous acquisition of two MR images with clearly different contrasts.

We present a new steady-state imaging sequence, which simultaneously allows in a single acquisition the formation of two MR images with clearly different contrasts. The contrast of the first image is FISP-like, whereas the second image is strongly T2-weighted. In principle the T2 values in the image can be calculated from the combination of the first and second images. We also show calculated T2 images.

Head↗
PubMed1988

[Short and long-term survival in fatal street traffic accidents].

Only persons who die within 30 days after an accident are primarily considered accident fatalities. This arbitrary deadline has considerable legal consequences, especially for health insurance companies. Advances in the immediate and optimal treatment for persons injured in traffic accidents at the site of the accident, as well as improvement in surgical techniques, have increased the number of fatalities, with the injured surviving for more than 30 days after the accident. An analysis of reports showed that about 5%-16% of deaths by accident survived the fatal accident for more than 30 days, so the arbitrary deadline of 30 days clearly needs to be revised.

Accidents, Traffic↗
PubMed1988

Noise analysis of cAMP-stimulated Na current in frog colon.

The effects of oxytocin and cAMP on the electrogenic Na+-transport in the short-circuited epithelium of the frog colon (Rana esculenta, Rana temporaria) were investigated. Oxytocin (100 mU.ml-1) elevated the short-circuit current (Isc) transiently by 70% whereas cAMP (1 mmol.l-1) elicited a comparable sustained response. The mechanism of the natriferic action of cAMP was studied by analysing current fluctuations through apical Na+-channels induced by amiloride or CDPC (6-chloro-3,5-diaminopyrazine-2-carboxamid). The noise data were used to calculate Na+-channel density (M) and single apical Na+-current (iNa). iNa-Values obtained with amiloride and CDPC were 1.0 +/- 0.1 pA (n = 5) and 1.1 +/- 0.2 pA (n = 6) respectively and unaffected by cAMP. On the other hand, cAMP caused a significant increase in M from 0.23 +/- 0.08 micron-2 (n = 5) to 0.49 +/- 0.17 micron-2 (n = 5) in the amiloride experiments. In our studies with CDPC we obtained smaller values for M in control (0.12 +/- 0.04 micron-2; n = 6) as well as during cAMP treatment (0.19 +/- 0.06 micron-2; n = 6). However, the cAMP-induced increase in M was also significant. We conclude that cAMP stimulates Na+-transport across the frog colon by activating "silent" apical Na+-channels. Thus, the mechanism of regulation of colonic Na-transport in frogs differs considerably from that in other vertebrates as mammals and birds.

Amiloride↗
PubMed1988

Evidence from nitrogen fertilisation in the forests of Germany.

In the first part, this contribution presents German results of nitrogen fertilisation experiments on stand growth, published 1958-1987. Over this period Norway spruce and Scots pine have generally responded positively to nitrogen fertilisation, without showing signs of damage, at levels up to at least 1000 kg N ha(-1). In the second part, growth patterns of forest trees and stands in Southern Germany are presented. Norway spruce in particular is now growing better than in earlier years of this century, starting around 1960. It is plausible that increasing nitrogen deposition, which coincides with the growth increase, is the cause, though this cannot be shown unequivocally. At a few sites with poor soil and management and high acid deposition a deterioration is taking place.

Journal Article↗
PubMed1988

The importance of nuclear magnetic relaxation dispersion (NMRD) profiles in MRI contrast media development.

Observation of the relaxivity of MRI contrast media over a wide range of magnetic fields is not only necessary for predicting their efficiency at any field but also compulsory for understanding and improving their mechanisms of action. The best experimental approach to this problem is the field cycling method, which allows the exploration of nuclear relaxation over a broad interval of magnetic field intensity but requires a specially dedicated instrument called a relaxometer. Particularly relevant are the relaxivity profiles of the two chelates Gd-DOTA and Gd-DTPA. Both show an important decrease from low to high fields within the current imaging range (0.02 T to 1.5 T). Although high field relaxivities of these chelates are similar, Gd-DTPA becomes less efficient in facilitating water protons relaxation at fields lower than 0.15 T. This behavior has to be related to different electronic relaxation times due to a different chelate symmetry.

Animals↗
PubMed1988

Whole-body MR imaging and spectroscopy with a 4-T system.

The clinical potential and limitations of magnetic resonance imaging and spectroscopy at 4 T were investigated with the use of a newly constructed system, which has been in use since January 1987. The magnet has a warm bore that measures 1.25 m in diameter, and its homogeneity in a sphere with a diameter of 50 cm is better than +/- 2.5 ppm. It was hypothesized that the improvement in the signal-to-noise ratio (S/N) afforded by the higher field strength would be useful in reducing imaging time and in improving spatial resolution. In experiments in human volunteers, believed to be the first in which an entire human body was exposed to a magnetic flux density of that magnitude, the subjects were exposed to 4 T for 10-30 minutes. They showed no changes in well-being or heart activity. The expected gain in spectral resolution due to chemical-shift scaling was achieved with the 4-T system, and an improvement in S/N was verified for phosphorus at 34 and 68 MHz. In sodium imaging, the high flux density appears to be useful in reducing imaging time, which should increase the usefulness of sodium imaging in evaluating brain tumors and strokes. In spectroscopy, the increase in flux density improves the quality of the spectra.

Electrocardiography↗
PubMed1988

A novel biologically active selenoorganic compound. VIII. Biotransformation of ebselen.

1. The metabolism of ebselen, a Se-containing heterocyclic compound, in rats, pigs and human volunteers has been investigated. 2. Unchanged ebselen is not present in urine, plasma or bile. All metabolites of ebselen have in common that the isoselenazolone ring is opened. 3. Both in pigs and human, the dominant metabolite in plasma and urine is a Se-glucuronide. This is the major metabolite in rats as well but, additionally, some selenomethyl-derivatives of ebselen can be detected.

Animals↗
PubMed1988

Practical application of the protein C activator Protac from Agkistrodon contortrix venom.

The protein C activator Protac from A. contortrix venom is being investigated as a potential antithrombotic agent and as a tool for the preparation of activated protein C. Its established major application is the zymogen activation in functional protein C determinations based on either a clotting assay or a chromogenic substrate technique. The sensitivity of the activated partial thromboplastin time as an indicator reaction for Protac activated protein C depends on the contact activator component of the reagent. Protein C dose-response increased in the following order: kaolin greater than ellagic acid greater than sulfatide. This phenomenon is due to a competition of molecular affinities between Protac, plasma components and the different activating surfaces.

Crotalid Venoms↗
PubMed1988

[Health pedagogic foster families. A model for the rehabilitation of handicapped children from families at-risk].

Rehabilitation of retarded children puts an enormous strain on parents. Families with various social risk factors are frequently not able to cope with these problems. Admission to institutes is a frequent consequence. Since 1982 47 mentally and psychologically handicapped children from families with various psychosocial problems were admitted to foster families. Foster parents were carefully selected and educated by a team of physicians, psychologists and social workers and given continuing supervision. Children were evaluated by medical and psychological testing: The majority of children showed significant improvement of performance in psychologic testing, alleviation in their psychosocial as well as medical problems. Numbers and duration of hospital admissions were substantially reduced. The overall condition of these children was markedly improved by foster families.

Child↗
PubMed1988

Endoscopy of the gallbladder as control of gallstone therapy with methyl-tert-butyl ether.

We report on a 36-yr-old woman with six gallstones measuring 2.1 cm each. Within 21 h of methyl-tert-butyl ether (MTBE) treatment, the stones had dissolved to a small amount of residue. As could be seen from cholesterol concentrations of samples of aspirated gallbladder bile and MTBE fractions, the dissolution process was slow to begin with, and gained momentum during hours 6-11, after which it decelerated. We discontinued treatment after 20 h, since the stone residue showed no change. Cholecystoscopy performed with an Edwards angioscope via a catheter showed that there were no stone remnants, but that there were flat polyps on the gallbladder wall. One hour later, we stopped the therapy. Cholecystoscopy is a useful method of assessing the results of MTBE treatment.

Adult↗