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Biomedical subjects

J Fischer

Publications and source records attributed to J Fischer.

At least 595 records · Page 33Linked to original sources
PubMed1976

[Effect of arterial hypoxia and acidosis on fibrillation threshold in the cat heart in vivo].

The influence of severe arterial hypoxia and acidosis on the fibrillation threshold was checked in 22 cats. Two groups were formed: in 10 cats (group I) acidosis was produced by 2-N lactic acid infusion; in the second group of 12 animals the respirator was turned off for 60 seconds, thus producing a low arterial PO2. If hypoxia and acidosis were severe enough, the fibrillation threshold was significantly lowered in either group. The pathophysiological mechanisms of these findings are discussed.

Acidosis↗
PubMed1976

The antidiuretic action of 1-deamino-8-D-arginine vasopressin (DDAVP) in man.

1. After administration of a new vasopressin analogue (DDAVP), a marked and prolonged antidiuresis occurred in 10 patients with pituitary diabetes insipidus. 2. The antidiuretic effects of single intravenous doses of 0.04--24 mug DDAVP and single intranasal doses of 5--320 mug DDAVP were investigated. Time curves of the antidiuretic responses expressed in changes of urine osmolality (Uosm) and free water clearance per 100 ml GFR (CH2O X 100/GFR) are described. 3. Maximal "peak" response was obtained after an intravenous dose of 1 mug within the first 12 hrs (Uosm was 7--800 mOsm/KgH2O). Further increase of dosage resulted only in prolongation of duration of action (up to 48 hrs) and peak ("plateau") effect (up to 24 hrs). 4. There was a linear relationship between the log dose and log osmolality of urine collected in the second 12 hours after administration of single intravenous and intranasal doses of DDAVP. 5. Comparison of the effects of 1 mug lysine-vasopressin and 1 mug DDAVP revealed only slight differences in peak effects, but extreme differences in duration of action. 6. It is concluded that in the evaluation of a synthetic vasopressin analogue the maximal antidiuretic ability and the prolongation of action have to be analysed separately.

Absorption↗
PubMed1976

[Direct quantitative measurement of tremor: first results of a new mesuring procedure in patients under lithium therapy].

The use of a new piezoresistive minature accelerometer as part of an electronic measurement system for the direct quantification of human finger tremor in physical units is described. The system was designed to yield digital values for the mean tremor amplitude in a given period of time. Reliability coefficients were computed for a smaple of 34 patients under lithium therapy. Coefficients ranged between 0.75 and 0.94 for test-retest intervals between 30 min and several days. Some of the usual indirect methods for the assessment of tremor showed very low correlations to the true tremor amplitude and seemed to be only of limited usefulness. It was further demonstrated that situational factors play a dominant role independently of the particular method of measurement.

Fingers↗
PubMed1975

Aldehyde bisulfite-toluidine blue (ABT) staining as a topo-optical reaction for demonstration of linear order of vicinal OH groups in biological structures.

The aldehyde-bisulfite-toluidine blue reaction followed by poststaining stabilization with potassium ferricyanide (ABT) is described as a topo-optical, oriented staining reaction of the vicinal OH groups of complex carbohydrates in biological structures such as polysaccharides, glycoproteins and glycolipids. The birefringence as induced by the oriented dye binding as a result of ABT is indicative of linear order of the vicinal OH groups and, in turn, provides information on the ultrastructural pattern of carbohydrate moieties in biological substances, which pattern is often not demonstrable by other ultrastructural methods. The possibilities of this new approach to the ultrastructural analysis of complex carbohydrates with ABT in a great number of biological substances is demonstrated and its practical value in histopathology discussed.

Aldehydes↗
PubMed1975

Termination of ventricular fibrillation in dogs by depolarizing a critical amount of myocardium.

The role of a critical myocardial mass required to maintain ventricular fibrillation initiated by rapid ventricular pacing was studied by two methods in dogs placed on total cardiopulmonary bypass. In the first method, depolarization of a limited myocardial mass was accomplished by injecting potassium chloride into one or two coronary arteries. Injection of potassium chloride simultaneously into the left circumflex and left anterior descending coronary arteries abolished ventricular fibrillation more often than did injection into any other single or combination of two coronary arteries (P less than 0.0001). Ventricular fibrillation could not be reinitiated as long as the left ventricle remained inexcitable. Immersing the heart in a solution of potassium chloride or injecting the solution into the right and left ventricular cavities failed to terminate ventricular fibrillation. The second method evaluated the amount of current necessary to terminate ventricular electrodes, between two left ventricular electrodes and between one right ventricular and one left ventricular electrode. Electrical shocks of equal magnitude terminated ventricular fibrillation most often when those shocks were delivered between an electrode located at the right ventricular apex and an electrode located at the posterior base of the left ventricle, and least often when the shock was delivered between two right ventricular electrodes. Successful defribillation results when a critical amount of myocardium becomes depolarized by either potassium chloride or electrical discharge; depolarization of every cell in both ventricle is not necessary to terminate ventricular fibrillation in the entire heart.

Animals↗
PubMed1975

Correlation between blood gases, glycolytic enzymes and EEG during electroconvulsive treatment in relaxation.

Twenty-three psychiatric patients were investigated during electroconvulsive treatment in relaxation. The blood gases, pH and serum bicarbonate levels in blood samples from the internal jugular vein and the femoral artery were measured radiometrically. The LDH fractions were separated electrophoretically and their activity, along with the activity of aldolase, was then determined on test materials. EEG recordings were made during the seizure and also during postconvulsive restitution. The following conclusions were drawn: (1) There was no evidence of anoxic anoxia in the brain during and after seizures. (2) A close relationship was found between the corresponding phases of electrical activity and brain metabolism as indicated by the blood gas changes during postconvulsive restitution. (3) On the basis of the increased glycolytic activity in the sera it is probable that glucose metabolism was shifted in the anaerobic direction during postconvulsive restitution of the brain tissues.

Adult↗