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Biomedical subjects

K Klein

Publications and source records attributed to K Klein.

At least 127 records · Page 7Linked to original sources
PubMed1979

Disruptive effects of disconfirmed expectancies about crowding.

The experiment utilized a 2 (high vs. low room density) X 2 (forewarning of a crowded room vs. no forewarning) X 2 (simple vs. complex task) design to examine the effects of anticipation of crowding on task performance. More tasks were attempted and efficiency was higher when expectancies about the crowd were confirmed. Subjects not told to anticipate a crowd who actually worked under high density and subjects warned about a crowd that did not materialize performed most poorly. These differences were largest for the complex task. Baum and Greenberg's results were replicated with the performance data. Perceptions of the experimental room also differed as a function of anticipation, but failure to obtain a Crowding X Anticipation interaction did not support their hypothesis that anticipating a crowd induces identical perceptions to those obtained under actual crowding. The results are discussed in terms of disconfirmed expectancies being disruptive of performance, particularly complex task performance.

Adult↗
PubMed1979

Inhibition of tritiated thymidine incorporation in cultured cells by rat kidney extract.

KCl extract from rat kidney, rat liver, and Morris hepatomas inhibited [3H]thymidine incorporation into cultured cells. Tissues came from male inbred BUF rats. The most pronounced inhibition was achieved with the kidney extract. Protein synthesis was not inhibited during a 24-hour exposure of the cells to the inhibitor. Incorporation of [3H]deoxycytidine was inhibited, as was cell growth, when the kidney KCl extract was present for several days. [3H]thymidine incorporation was inhibited almost immediately after the addition of the extract. The inhibition was reversible. Regular [3H]thymidine incorporation was restored 24 hours after removal of the inhibitor, which was neither arginase nor a thymidine-degrading enzyme. The inhibitor was stable to heat (80 degrees C for 10 min) and resistant to trypsin, pronase, DNase, and RNase. Exposure of the extract to proteolytic enzymes, hyaluronidase, and neuraminidase resulted in a loss of inhibitory activity only after extensive dialysis of the treated extract. The inhibitor appeared to be a mucoprotein in which the carbohydrate moiety may be responsible for the inhibition. The KCl extract also inhibited RNA synthesis and DNA synthesis by the de novo pathway. The inhibition of phosphorylation of thymidine, however, appeared to be the primary action of the inhibitor.

Animals↗
PubMed1977

Effect of camptothecin and adriamycin on bleomycin-induced tritiated thymidine triphosphate incorporation in a rat nuclear system.

We investigated the effect of camptothecin and adriamycin on [3H]TTP incorporation and bleomycin-stimulated [3H]TTP incorporation in host liver and hepatoma nuclei of rats. Camptothecin neither stimulated nor inhibited incorporation in the regular nuclear incorporating system. Bleomycin stimulated incorporation to a much greater extent in host liver nuclei and slow-growing hepatomas than it did in the fast-growing hepatoma 7777. Addition of camptothecin to bleomycin stimulated incorporation of [3H]TTP even further. This camptothecin stimulation was slightly greater in hepatoma nuclei than it was in host liver nuclei. Adriamycin inhibited [3H]TTP incorporation in the regular system as well as the bleomycin-induced incorporation. Hepatoma nuclei were more sensitive to this inhibition than were host liver nuclei. Sucrose density gradients indicated that camptothecin caused DNA strand scissions in addition to those produced by bleomycin. Camptothecin alone produced some single-strand but no double-strand scissions. The action of bleomycin was dependent on sulfhydryl-reducing agents. Camptothecin could partially substitute for this requirement. Adriamycin did not produce DNA breaks as determined by neutral or alkaline sucrose density gradients. Despite complete inhibition of bleomycin-induced [3H]TTP incorporation, adriamycin did not prevent bleomycin-induced DNA breaks. The inhibitory effect of adriamycin might have been on the repair system.

Animals↗
PubMed1977

The effect of several antitumor agents on 3H-TTP incorporation in host liver and hepatoma nuclei.

Six different tumor antibiotics have been investigated in a nuclear incorporating system for their ability to inhibit 3H-TTP incorporation. Both host liver nuclei and nuclei prepared from two different Morris hepatomas have been used in the investigation. Three of these anti-tumor agents inhibit 3H-TTP incorporation equally in host liver and hepatoma nuclei, two preferentially inhibit incorporation in hepatoma nuclei and one stimulates incorporation preferentially in host liver nuclei. The effects of these compounds on nuclear DNA has been analyzed on neutral and alkaline sucrose density gradients. The nuclear incorporation system appears to be useful as a screening test system for potential anti-tumor agents.

Animals↗
PubMed1977

Inhibition of bleomycin-induced [3H] thymidine 5'-triphosphate incorporation into liver and hepatoma nuclei by N-ethyl maleimide and daunomycin.

The addition of bleomycin to a nuclear incorporating system results in an increased incorporation of 3H-thymidine 5'-triphosphate (3H-TTP) into the DNA of liver and hepatoma nuclei. Bleomycin added to the nuclear incorporating system also produces scissions of DNA as determined by sucrose density gradient centrifugation of the extracted DNA. The action of bleomycin is dependent on the presence of sulfhydryl agents in the incubation mixture. Two compounds, N-ethyl maleimide and daunomycin, inhibit the bleomycin-induced incorporation of 3H-TTP preferentially. N-Ethyl maleimide inhibits bleomycin-induced activity in liver and hepatoma 7777 nuclei equally. Lower levels of daunomycin inhibit the bleomycin-induced activity in the hepatoma 7777 nuclei than are required to inhibit the activity in liver nuclei. The two compounds inhibit the bleomycin effect by different mechanisms. The addition of N-ethyl maleimide to bleomycin in the incubation system prevents bleomycin from causing breaks in the DNA. The addition of daunomycin, despite inhibition of bleomycin-induced 3H-TTP incorporation, does not affect the bleomycin-produced breaks in the DNA. N-Ethyl maleimide acts by binding to the DNA and by competing with a sulfhydryl agent for bleomycin-sensitive sites on the DNA. Daunomycin apparently inhibits a repair enzyme that is responsible for the increased incorporation following bleomycin treatment.

Animals↗
PubMed1976

[Evidence for the action of raubasine from a new formulation of Lamuran tablets].

It was possible in a controlled double-blind study to demonstrate by means of dynamographic measurements the action of raubasine in patients with cerebrovascular disorders. A new formulation of Lamuran tablets (MF706d) was used for the investigation. This formulation has an improved in-vitro dissolution rate for raubasine that is largely independent of pH. In the raubasine group (10 patients aged 47 to 81 years, including 6 cases of anacidity) there was after one and two weeks treatment with dialy doses of 90 mg raubasine a significant reduction of the raised vascular resistance and pulsewave velocity and systolic blood pressure in the internal carotid artery which indicate an improvement in cerebral haemodynamics. In contrast, no significant changes in these parameters could be found in the placebo group (9 patients aged 52 to 83 years). The therapeutic relevance of the haemodynamic effects was supported by a simultaneous clinical improvement.

Achlorhydria↗
PubMed1976

Evaluation of a serum protein in pregnant rats.

The increase of a serum protein in the circulation of rats during pregnancy has been described. The protein is different from the human pregnancy zone protein previously described. This new serum protein factor is present in normal rat serum and accounts for approximately 1% of the total serum protein. The protein factor disappears from the serum of animals bearing Morris hepatomas 7777 and 7800. The amount of factor diminishes as the tumors increase in size. The levels of this protein in the serum increased several fold during pregnancy with highest levels found shortly before parturition. Levels remained elevated for at least 12 days post partum. No corresponding increase in the levels of this serum factor in the fetal circulation was observed. Increased levels in the maternal circulation were due to an increased synthesis of this serum protein during pregnancy. A corresponding band was observed on polyacrylamide gels for normal human female and pregnant human sera or plasma. However, there was no increase during pregnancy as judged by polyacrylamide gel electrophoresis. Quantitative determination of the protein in human sera was not possible since the band corresponding to the serum protein in rats did not cross react with a rabbit anti-rat serum factor.

Animals↗
PubMed1976

[Use of ultrasound methods in vascular and circulatory diseases (author's transl)].

The paper summarizes the principles, techniques and efficiency of ultrasound methods as indicator systems in the assessment of the peripheral and cerebral arteries; our studies predominantly refer to the use of these simple, non-invasive procedures in combination with sphygmo-oscillography and dynamographic circulation analysis, respectively. Ultrasound Doppler flowmetry (Pulse Doppler method), which permits relative measurements of the flow velocity in the peripheral haemodynamic regions, is of great importance in the rapid ascertainment of the patency of the major arterial trunks and the non-palpable vessels and also in the diagnosis, localization and follow-up control of stenoses and occlusions. Changes in the flow velocity due to organic or functional factors can be recorded by this method acoustically, oscilloscopically and graphically; measurements of the systolic blood pressure in the limb arteries by the Doppler technique provide semi-quantitative information in regard to the condition of the circulation. The registration of Doppler signals over the supra-orbital artery before and after compression of the superficial temporal artery and the common carotid artery has become established as a screening procedure for stenoses of the internal carotid artery. Ultrasound echography, which enables pulse registration and determination of vessel diameters, especially of the carotid siphon, can also be used for the detection of obstructions in the region of the internal carotid artery, as well as the vertebral artery.

Auscultation↗