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Biomedical subjects

A Hartmann

Publications and source records attributed to A Hartmann.

At least 523 records · Page 29Linked to original sources
PubMed1981

Effect of pentoxifylline on regional cerebral blood flow in patients with cerebrovascular disease.

A previous study showed that regional cerebral blood flow, measured following intra-arterial injection of 133Xenon, increased by at least 15% in one-third of all areas investigated in 25 patients with different types of dementia after a 2-weeks' period of intravenous treatment with 600 mg pentoxifylline per day. In the present studies, 10 patients were treated orally with 400 mg pentoxifylline 3-times daily for 4 weeks and 10 untreated patients served as controls. Regional cerebral blood flow was measured over both hemispheres using a new non-invasive technique by inhalation of 133Xenon gas. Bihemispheric cerebral blood flow increased by 15.9% in the pentoxifylline group and by 1.7% in the controls. Hypoemic areas, in particular, showed a distinctly higher increase (+20.1%) in blood flow after pentoxifylline compared to controls (+0.7%), and these hypoemic areas were apparently more influenced than hyperemic or normoemic regions. These findings were confirmed by a second controlled series. These data suggest an improvement of cerebral blood flow by pentoxifylline in a certain number of brain tissue areas if the drug is given over periods of at least 2 weeks in patients with cerebrovascular disease and other types of dementia.

Aged↗
PubMed1980

[Treatment of acute subarachnoidal hemorrhage].

Acute subarachnoid hemorrhage is influenced by cerebral edema, acute obstructive extraventricular hydrocephalus with high or normal intracranial pressure and vascular spasms. Computertomography, angiography and continuous monitoring of cerebral spinal fluid pressure are helpful tools in preventing early worsening of the clinical condition. Indications of monitoring the cerebral spinal fluid pressure depends on clinical grading. Therapy of vascular spasms remains an unsolved problem.

Antifibrinolytic Agents↗
PubMed1980

Oscillation of the electric potential of frog skin under the effect of Li+: experimental approach.

When a frog skin is used to separate two compartments, and lithium is added to the external medium, transmembrane electric potential oscillations frequently occur. When no external current is imposed, sustained oscillations, with a period of about 10 min, are maintained for several hours. An oscillation of the Na+ influx accompanies the electric oscillation, though the two oscillations are out of phase to a greater or less extent. Theophyllin promotes a significant decrease in the mean electric potential of the skin, but it does not affect very much the characteristics of the oscillation. Important factors influencing the oscillation are temperature, permeability of the external membrane to lithium, and potassium concentration in the internal medium. No correlation can be detected between oscillation characteristics and skin area. This suggests that the oscillation is of a local nature, possibly originating at the cellular level. Occurrence of macroscopic oscillations implies coupling between local oscillators. Coupling between two epithelia has been studied under diverse conditions. The coupling is of an electrical nature: by varying the value of the coupling resistance, it is possible to control synchronization of the oscillations.

Animals↗
PubMed1980

A tracer method to study unidirectional fluxes of lithium. Application to frog skin.

We describe a new tracer method to measure unidirectional fluxes of Li+ despite the lack of any utilizable radioisotope of lithium. This method uses the purified stable isotopes, 6Li and 7Li, detected with an ion-probe microanalyser. The accuracy is comparable to that obtained for other ions (e.g., Na+) with radiotracers. The method has been applied to frog skin with both faces bathed in a 20% lithium/80% sodium medium. Sodium and lithium unidirectional fluxes have been measured simultaneously. The results are consistent with lithium being actively pumped, the outflux of lithium being, however, much larger than that of sodium.

Animals↗
PubMed1980

[Health hazards caused by wood in Switzerland].

The clinical signs and symptoms of health hazards caused by wood are discussed together with their etiology and pathogenesis. 165 such cases were reported to the SUVA (Swiss Accident Insurance Association) up to the end of 1978. Disorders were most common among workers having the greatest exposure to the fine wood dust produced by tropical woods (in particular during grinding and cutting processes). 130 patients suffered from allergic contact eczema or non-allergic contact dermatitis. 35 patients suffered from respiratory tract disorders, 12 of these being classic bronchial asthma. Reference is made to the literature which points to the sharply increased incidence of adenocarcinoma of the paranasal sinus after long-term exposure to wood dust.

Asthma↗
PubMed1980

Iron transport in Escherichia coli: uptake and modification of ferrichrome.

During the transport of iron as ferrichrome complex into cells of Escherichia coli K-12, the ligand was modified and excreted into the medium. The rate of the formation of the modified product corresponded with the rate of iron transport. The modified product showed a decreased affinity for ferric iron and did not serve as an effective iron ionophore. After all of the ferrichrome had been converted, the modified product was taken up into the cell in an iron-free form. The uptake of ferrichrome and of the modified product depended on the transport system specified by the tonA and tonB genes. The modified product could be converted back into ferrichrome by mild acid or alkaline hydrolysis. One mole of acetate was released per mole of ferrichrome. It is proposed that one N-hydroxyl group of ferrichrome is acetylated to explain the low affinity for iron as the N-hydroxyl groups form the ligands for iron (III). A weak ester linkage by which the acetyl group is covalently bonded would account for the easy hydrolysis. The iron-free form of ferrichrome, deferri-ferrichrome, was also rapidly converted when incubated with cells with a functional transport system. It is therefore likely that iron is released from ferrichrome by reduction before modification takes place. The conversion of the ligand could be a mechanism by which cells rid themselves of a potentially deleterious ligand for iron in the cytoplasm. A possible role in ferrichrome transport is discussed.

Acetates↗
PubMed1979

Uptake and conversion of the antibiotic albomycin by Escherichia coli K-12.

The antibiotic albomycin is transported into cells of Escherichia coli K-12 by the same uptake system as the iron-supplying ferrichrome complex. The iron-complexing hydroxamate moieties of albomycin and ferrichrome are structurally similar. During the phase of rapid iron uptake the chelators were not found in the cells. In order to understand the antibiotic activity of albomycin, it was labeled in the hydroxamate with tritium and in the presumed antibiotically active area with radioactive sulfur. While the tritium label was not retained by the cells, part of the sulfur label was taken up and concentrated 500-fold within the cell. The sulfur was not incorporated into proteins or nucleic acids since it was recovered as a low molecular weight component. Gel filtration on Bio-Gel P-2 revealed one tritium-labeled and two sulfur-labeled cleavage products in the incubation medium. We conclude that albomycin is actively transported via its ferrichrome-like portion into the cells and that the growth-inhibitory moiety is released by hydrolysis intracellularly and remains there.

Anti-Bacterial Agents↗
PubMed1978

[Cerebral and blood flow and cerebral blood volume in communicating hydrocephalus (author's transl)].

Regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) were estimated in patients with communicating hydrocephalus, arteriosclerotic and presenile dementia. In all groups ischemic patterns were detected which did not allow any differential diagnostic separation between the patients. In some patients with communicating hydrocephalus reduction of cerebrospinal fluid pressure by lumbar puncture or ventriculoperipheral shunt respectively resulted in increase of rCBF and rCBV. This was not achieved in the other patients with dementia. Predominantly areas with ischemic flow values gained profit from reduction of CSF pressure. This was interpreted as a sign of regional damage to the autoregulation.

Alzheimer Disease↗
PubMed1978

The effect of large doses of dexamethasone on the cerebrospinal fluid pressure in patients with supratentorial tumors.

The effect of large doses of dexamethasone (80 mg) on the cerebrospinal fluid pressure (CSFP) was investigated with continuous lumbar CSFP measurement over 24 h in 10 patients with supratentorial cerebral tumors and clinical signs of elevated intracranial pressure. There was a further slight rise in CSFP with an unchanged pressure pattern in the course of observation of the untreated control group. A marked lowering of CSFP was observed within 6 h after initial intravenous administration of dexamethasone to seven of the treated patients. In four of the treated patients an unequivocal and in five only a moderate CSFP lowering was measured at the end of the registration. One patient had a slight rise in pressure. The plateau waves of all the patients treated decreased in height, frequency and duration within the first hours, while fluctuations in pressure level and CSFP amplitude were reduced.

Aged↗
PubMed1977

Effects of a new diuretic on cerebrospinal fluid pressure in patients with supratentorial tumors.

The effect of a new, powerful diuretic on biochemical parameters, urine output, central venous pressure, blood pressure, and cerebrospinal fluid pressure in patients with supratentorial intracerebral tumors who showed signs and symptoms of increased intracranial pressure was tested. When compared to an untreated control group and to the steady-state data of each patient, CSF pressure was significantly reduced using a dose of 240 mg of the diuretic. The 120 mg dosage did not produce significant results. Normalization of increased cerebrospinal fluid pressure was not completely obtained using either dose. Used alone, this substance is not suitable for treatment of increased intracranial pressure due to brain edema in patients with intra-cerebral tumors. It might, however, be useful in combination with other medications.

Brain Edema↗
PubMed1977

[Lithium exchange in from epithelium: determination of unidirectional flux using the stable isotopes 6Li and 7Li in an ionic analyzer].

The use of the stable isotopes 6 and 7 of lithium, and detection with the ionic analyser, allow the measurement of unidirectional transepithelial Li-fluxes, between "external" and "internal" solutions which both contain 80% Na and 20% Li. Efflux was found to be bigger than influx. An important lag-phase on the curve, reveals the interference of a Li-compartment, with a high capacity, in the epithelium itself.

Animals↗