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Biomedical subjects

D Schmidt

Publications and source records attributed to D Schmidt.

At least 577 records · Page 32Linked to original sources
PubMed1980

[Modification of light-evoked potentials depending on the feeding behavior of rabbits. I. Dependence on motivational state].

Flash evoked potentials (EP) from visual cortex, dorsal hippocampus, and other brain structures were recorded during various behavioral situations in freely moving rabbits. The aim of the study was to investigate the direction and rate of EP-changes after a two-day food deprivation. Potentials evoked during slow wave sleep had not shown any systematical changes after the food deprivation. Considerable changes, almost synchronously in different structures, were observed during an active food expectance in a pseudoconditioning experiment in contrast to the hungry sleep state. Prominent was a significant reduction in peak latency and amplitude of the primary components, a massive positivation (surface negativation) in the early section of the potentials (30-100 ms), a depression of the late negative complex in visual cortex and the appearance of early components in the sensomotory cortex. Our results show that outside the typically motivational centers a short food deprivation causes changes in evoked neuronal activity only during a certain motivational level. Considering similar EP-configurations in otherwise motivated wakefulness, the participation of nonspecific and also motivational specific mechanisms of activation is discussed.

Animals↗
PubMed1980

[Asphyxial shock and disseminated intravascular coagulation (DIC) in animal experiments. 1. Histological picture (author's transl)].

The effects of subacute intra-uterine hypoxia on the haemostatic system of 205 foetuses from 49 pregnant rabbits were studied by a standardised experimental arrangement, with particular reference being made to intravascular precipitation of fibrin. The asphyxial shock thus induced was accompanied by almost all the rabbit foetuses by disseminated intravascular coagulation by which the central organs were more strongly affected, as compared to peripheral organs also restricted by the shock. The pathophysiological processes which were found to take place in the lungs and placentas of the experimental animals proved different from those in man, which was attributable to species-related differences.

Animals↗
PubMed1980

[Asphyxial shock and disseminated intravascular coagulation (DIC) in animal experiments. 2. Morphometric tests and blood coagulation studies (author's transl)].

First intravascular coagula were detected as early as in the pre-acidotic phase of artificially hypoxic rabbit foetuses used by the authors in experimental studies. Growing acidosis in circulating blood has been accompanied by excessive increase of fibrin precipitation in the terminal blood track. Further increase of intravascular coagulation was found to be discontinued by predominance of secondary fibrinolysis at blood pH around 6.9. Rising hydrogen ion concentration, as a reflection of a consumptional reaction, was found to be accompanied by decline in both the fibrinogen level and thrombocyte count in the foetal blood, fully in parallel with the above DIC.

Animals↗
PubMed1979

Visualization of pi- and pi+ stopping density distributions in one and two dimensions.

A technique suitable for mapping pi+/- stopping density distributions in patients or phantoms is described. As a position sensitive detector a multiwire proportional chamber with a slit or a hole collimator in front was applied. Results using a water and a Rando phantom are presented for various momenta and momentum band widths of the pi+/- beam. To our knowledge the two-dimensional visualization of a pi- stopping density distribution was realized for the first time.

Elementary Particles↗
PubMed1979

Latent, manifest latent, and congenital nystagmus.

Manifest latent nystagmus (MLN) was identified in 31 patients by accurate eye movement records. All the patients had horizontal tropias, and the nystagmus fast phases were always in the direction of viewing eye. The slow phases of MLN are decreasing-velocity exponentials while those of the jerk form of congenital nystagmus (CN) are increasing velocity exponentials. Several subjects who were believed to have latent nystagmus (LN) on clinical examination had small amplitude nystagmus evident by eye movement recording with both eyes open: these were actually cases of MLN. Many patients with MLN are misdiagnosed as having CN. An explanation for MLN and LN is provided based on confusion of egocentric directions between monocular and binocular viewing conditions.

Adolescent↗
PubMed1979

Circulatory pattern and duration of action of naloxone in dogs with and without opioid pretreatment.

We investigated the circulatory pattern of naloxone reversal after high-dose fentanyl infusion in dogs. Within 1 min there was a sudden decrease in total peripheral resistance with a concomitant increase in stroke volume index. All other parameters changed back in direction of pre-fentanyl values in various degrees with peak effects in about 3-7 min. The persistency of reversal was different for individual parameters, but 20 min after injection of naloxone almost all changes induced by antagonisation of narcotic activity had returned to pre naloxone levels. In a control series with animals not pretreated with opioid, naloxone was shown to have no specific pharmacologic action of its own.

Animals↗
PubMed1979

[The haemodynamic effects of dobutamine and dopamine in patients with coronary artery disease. A study performed under general anaesthesia (author's transl)].

The haemodynamic effects of dobutamine (2 microgram/kg . min and 4 microgram/kg . min) and dopamine (4 microgram/kg . min and 8 microgram/kg . min) were studied in 17 patients with coronary artery disease prior to coronary bypass surgery. The study was performed under general anaesthesia (modified neurolept analgesia) and controlled ventilation. Dopamine improved cardiac index significantly, increased mean aortic pressure slightly while heart rate and total peripheral resistance remained unchanged. Dobutamine failed to increase cardiac and stroke index significantly, but increased mean aortic pressure distinctly due to an elevated total peripheral resistance. Both catecholamines increased left ventricular filling and mean pulmonary artery pressure. The HR x ASP-product which is closely related to left ventricular oxygen consumption was found to be augmented to a greater extent during dobutamine. For the above reasons dopamine should be favoured for increasing cardiac output in patients undergoing aortocoronary bypass surgery. Our study does not confirm earlier results which have shown dobutamine to be the preferable catecholamine. The possible reasons for this discrepancy are discussed.

Adult↗
PubMed1979

Certification of medical librarians, 1949--1977 statistical analysis.

The Medical Library Association's Code for Training and Certification of Medical Librarians was in effect from 1949 to August 1977, a period during which 3,216 individuals were certified. Statistics on each type of certificate granted each year are provided. Because 54.5% of those granted certification were awarded it in the last three-year, two-month period of the code's existence, these applications are reviewed in greater detail. Statistics on each type of certificate granted each year are provided. Because 54.5% of those granted certification were awarded it in the last three-year, two-month period of the code's existence, these applications are reviewed in greater detail. Statistics on MLA membership, sex, residence, library school, and method of meeting requirements are detailed. Questions relating to certification under the code now in existence are raised.

Canada↗
PubMed1979

Saccadic velocity characteristics: intrinsic variability and fatigue.

Saccadic eye movements exhibit a characteristic peak velocity vs. amplitude relationship. As with all quantifications of biological function, there exists and associated intra- and intersubject variability of this relationship. This paper documents this variability and demonstrates both the absence of a predictable short-term "muscle fatigue" effect and the presence of a generalized "mental fatigue" (i.e. tiredness) effect.

Adolescent↗
PubMed1979

[High doses of thiopental for therapy of post-ischaemic anoxia of the brain. A case report (author's transl)].

The case of a 7-year-old child is presented, who suffered circulatory arrest during induction of anaesthesia for surgery for a posterior fossa tumour. A brain ischaemia lasting 6 minutes duration had to be assumed. After restoration of circulation, 825 mg ethiopenta were administered in order to ameliorate a possible post-ischaemic anoxia of the brain according to a protocol by Safar [18]. 11 hours after circulatory arrest the child awoke. Except for a more pronounced left sided hemiparesis and paresis of the left n. abducens no additional neurological deficit was observed compared to the neurological status before induction of anaesthesia.

Anesthesia↗
PubMed1979

[Influence of starvation on the heart rate of rabbits].

The ECG was recorded in rabbits during EEG-controlled slow wave sleep and during food conditioning sessions. A 2-day food deprivation caused a significant slowing of mean heart rate during sleep. The heart rate increased in hungry animals waiting for food (food expectancy), but did not reach the values of saturated sleeping animals.

Animals↗
PubMed1979

[Animal experiments to study placental passage of Sombrevin and Hexobarbital and their concentrations in various foetal organ systems (author's transl)].

Studies were conducted into 55 rabbits and their 327 foetuses to measure the two intravenously applied anaesthetics, Sombrevin and Hexobarbital, for their passage through the placenta and for the concentrations which eventually settle in various organ systems of the foetuses. Fast placental passage, but in different concentrations, was established for either anaesthetic. Sombrevin was found to reach the foetal organism only in low quantity and for short-time retention, whereas Hexobarbital passed the placental barrier in much higher concentration to stay detectably for a longer period of time in the foetal blood. While Sombrevin was not recordable from foetal organs, its intraplacental buildup reached higher concentrations. Relatively high concentrations of Hexobarbital were recordable from both the placenta and vital foetal organs. The conclusions so far derived from those animal experiments seem to suggest a superiority of Sombrevin over Hexobarbital and regard to applicability to obstetric anaesthesia.

Animals↗