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Biomedical subjects

J Schmidt

Publications and source records attributed to J Schmidt.

At least 829 records · Page 46Linked to original sources
PubMed1978

Xenon contrast enhancement in computed body tomography.

Xenon has been investigated as a contrast medium for conventional radiography, and in vitro as a contrast medium for computed tomography. The authors evaluated xenon contrast enhancement in vivo for CT body scanning. Nine healthy subjects had CT scans before and during xenon inhalation. Concentrations of xenon used varied from 10--50%. Consistent useful changes in attenuation from inhaled xenon were found in the lung but not in abdominal organs. Lung attenuation varied linearly with the xenon concentration in the inhaled gas. Inhalation of xenon concentrations greater than 30% resulted in side effects. Further studies are required to demonstrate whether xenon contrast enhancement is of diagnostic value in computed tomography.

Clinical Trials as Topic↗
PubMed1978

[Immunological problems of influenza virus infections].

Reference is made to results reported in literature as well as to some of the author's own findings for a summary account of specific immune responses to influenza virus infections. Some introductory comments on the correlations that exist between morphology and function of structural components of the influenza virus as well as on the pathogenesis and its relevance to the immunological responses are followed by a description of the humoral immune response. An assured correlation has been found to exist between the titres of hemagglutination-inhibiting antibodies with responses specific of subtypes and of strains for the protection against homologous influenza virus infection in terms of prevention of outbreak or mitigation of the pathological course. Anti-neuraminidase antibodies have influence upon virus expansion in the organism and in the given population as well as upon the severity of the disease. Particular importance has been attributed to the secretory immunoglobulins. Used in conjunction with interferone, they obviously had an infection-preventing function, wheras the primary role of serum anibodies was a reduction of severity. The studies into cell-mediated immune responses were much less intensive than those conducted into antibody formation. Cell-mediated immune response is thought to emanate from induction of hemagglutinin and is directed against the latter. Sufficient results have not become available as yet on the importance of cellular immune response to protection.

Animals↗
PubMed1977

Two types of receptors for alpha-bungarotoxin in the synaptic layers of the pigeon retina.

Pigeon retinae were analyzed for binding [125I]alpha-bungarotoxin (alphaBgt) by radioautographic and biochemical methods. Toxin binding, localized to the outer and inner plexiform layers (OPL and IPL), was inhibited by micromolar concentrations of native alphaBgt and D-tubocurarine and by 1 mM acetyl- and butyrylcholine in both synaptic layers. Nicotine, at comparable concentrations affected only the IPL. In vitro drug competition experiments showed that the pigeon retina contains two types of receptors for alphaBgt which differ in sensitivity to inhibition by nicotine by 4 orders of magnitued. The results suggest that: (1) the receptor for alphaBgt in the IPL is a nicotinic receptor, (2) the receptor for alphaBgt in the OPL may be involved in an unusual cholinergic system, and (3) ability to bind alphaBgt is not a sufficient criterion for identifying nicotinic-cholinergic receptors.

Animals↗
PubMed1977

[Use of a computer for the preparation of medical history screening in cardiovascular diseases].

Questionable data may be regarded as significant indicators for a screening. It is the aim of our investigations to develop a screening standard anamnesis in form of a questionaire which allows on the scale of larger groups of population to establish the number of endangered persons and patients who probably suffer from cardiovascular diseases but of the quantity of apparantly healthy persons. In order to recognize regularities of the diagnostics coordination of the individual patient by his answers on the questionnaire the data of 400 diagnostically clarified persons (model experiment) underwent a discriminancy analysis. When the data of unknown test persons are given in, on account of the well-known functions of discriminancy a classification in the groups persons with heart and circulatory diseases or with a healthy heart and circulation or a group diagnosis can be performed, respectively. The evaluation of the data of unknown test persons of a pilot study in 96% resulted in a correct classification in patients with heart and circulatory diseases or persons with healthy heart and circulation, the classification in the above mentioned groups of diagnosis was performed on an average to 57%.

Cardiovascular Diseases↗
PubMed1977

Tetanus toxin induced actions on spinal Renshaw cells and Ia-inhibitory interneurones during development of local tetanus in the cat.

In anaesthetized cats the activities of Renshaw cells (RCs) and Ia-inhibitory interneurones (IaINs) were recorded during the accumulation of tetanus toxin in the spinal cord following injection into the gastrocnemius muscle. The early response of the RCs increased during the period of development of local tetanus. With some cells there was a subsequent decrease in the early response in later periods of the observation time (16-44 hrs after intramuscular injection). The effects on the spontaneous activity of the RCs were in good correspondence to those on the early response. The hyperactivity of the RCs is proposed to be mediated mainly via disinhibited cholinergic gamma-motoneurones using muscarinic postsynaptic receptors. The "pause" which follows the early response and the recurrent inhibition of IaINs was not reduced during the development of local tetanus. These results indicate that the central action of tetanus toxin in local tetanus does not consist of a general loss of postsynaptic inhibition. It is suggested that tetanus toxin acts mainly on synaptic elements of the alpha- and gamma-motoneurones or on presynaptic nerve terminals in their vicinity. In later periods of disturbing influence on the cholinergic transmission at Renshaw cells seems to occur.

Animals↗
PubMed1977

DNA polymerases from intracisternal A-type particles on the mouse plasmacytoma MPC 11.

Intracisternal A particles from mouse plasma cell tumors were isolated from microsomal vesiclels by detergent treatment and separated in linear sucrose gradients. Four peaks of DNA polymerase activities banding at densities of 1.30, 1.24, 1.20--1.22 and 1.13 g/cm3 were observed assaying on poly(rA).oligo(dT). Solubolized DNA polymerases of the 1.30 g/cm3...

Animals↗