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Biomedical subjects

S Klein

Publications and source records attributed to S Klein.

At least 379 records · Page 21Linked to original sources
PubMed1981

Properties of the Photosynthetic System and DNA of Cyanophora paradoxa Cyanelles.

The cyanelle from the photosynthetic biflagellate protist Cyanophora paradoxa has been studied in terms of its photosynthetic properties. Structurally, the cyanelle resembles unicellular cyanobacteria. The cyanelle is readily released from the host cell by means of the French press. The isolated cyanelle shows typical photosystem I and photosystem II activities as well as phenazine methosulfate-mediated photophosphorylation. The kinetic parameters K(m) and V(max) were determined for CO(2) fixation in the cyanelle and cells of C. paradoxa and compared to a cyanobacterium. The determined values were not much different, although the cyanobacterium had a significantly greater rate of CO(2) fixation, and the cyanelle was least active in this regard. Photosystem I chlorophyll-protein complex is readily isolated from the thylakoid membrane. In all these respects, the photosynthetic apparatus of the cyanelle resembles that of cyanobacteria. No nitrogen fixation activity was observed. Attempts to regenerate the isolated cyanelle were not successful, but in some cases, an unidentified cyanobacterium grew up in standing cultures of C. paradoxa cyanelles. Buoyant density data indicate that the strain of C. paradoxa we have investigated differs from that employed by others, since our strain shows a value of 1.716 grams per cubic centimeter and others report values of 1.695 and 1.691.

Journal Article↗
PubMed1981

HL-A antigen frequency distribution in patients with gestational choriocarcinoma and their husbands.

HL-A (A,B,C, and DR) antigen frequency distribution was determined in 29 patients with choriocarcinoma and in their husbands, as well as in a matched control population of 21 healthy couples. All 29 patients had achieved complete sustained remission with chemotherapy. The HL-A antigen frequency distribution was normal in the choriocarcinoma patients and in their husbands and there was no abnormal HL-A antigen sharing between patients and their husbands. This study does not exclude the possibility that the pathogenesis of resistant choriocarcinoma may be dependent upon tumour-host histocompatibility.

Choriocarcinoma↗
PubMed1981

Correlation between plasma sodium acetate concentration and systemic vascular resistances.

Acetate in dialysis fluid induces during haemodialysis a fall in systemic vascular resistance. In patients with hepatic insufficiency, acetate concentrations are higher than in patients without hepatic insufficiency and in such patients vascular sensitivity to acetate is perhaps potentiated by modifications of acid base status. The close inverse correlations between acetate concentrations and systemic vascular resistance are strong indications that acetate is a major factor involved in the genesis of 'dialysis hypotension'.

Acetates↗
PubMed1981

Effect of surface porosity on early thrombogenicity using vascular grafts with two surfaces in sequence.

This experiment addresses the multifactorial dilemma of defining the ideal performance parameters of small internal diameter vascular grafts. We found silicone rubber vascular grafts with smooth surfaces remain acutely free of thrombotic deposits whereas grafts with rough surfaces promote a dispersed thrombus formation. This study also questions the concept that the thrombogenicity of one surface determines the thrombotic response of different and adjacent flow surfaces in the blood flow. Here the distinction between response to each surface was abruptly delineated and equal in intensity regardless of proximal or distal positioning. By studying the 2 surfaces in sequence, surface properties were evaluated using the minimal number of experiments by mitigating the effects of interanimal variability. This is an important consideration in an era of "cost accountability".

Animals↗
PubMed1980

Resistance to extinction of a taste aversion: effects of level of training and procedures used in acquisition and extinction.

Two studies investigated the relationship between acquisition and extinction procedures on the development and elimination of a taste aversion. In the first experiment, subjects were given either forced or free choice acquisition to a common acquisition criterion. Then, their aversion was extinguished under either the free or forced choice procedure. The results of the first study showed that the greatest resistance to extinction was produced with a forced acquisition and free extinction procedure and the least resistance was produced by a free acquisition and forced procedure. Experiment 2 employed an equal number of acquisition trials (one or three) under either free or forced acquisition followed by either free or forced extinction. The results of Experiment 2 found that resistance to extinction was greater with three compared with one acquisition trial, but the acquisition technique did not influence resistance to extinction. As in the first experiment, extinction was more rapid with forced extinction. It appears that the strength of a taste-illness association is primarily dependent on the number of CS-US associations. Thus, when a common criterion is used, forced subjects take longer to extinguish their aversion due to their stronger taste-illness association. When an equivalent number of pairings is used, extinction rats are equal in free and forced animals (even though acquisition intake was higher in forced animals).

Animals↗
PubMed1980

Tumor delayed hypersensitivity reactions. "In vivo" functional differences between spleen and peripheral blood lymphocytes.

In a syngeneic BALB/c transplantable tumor model, specific delayed hypersensitvity reaction, detected by foot-pad swelling test appeared specifically suppressed or "eclipsed" in advanced tumor bearing mice. This "eclipsed" response could not be reversed after tumor resection. Unresponsiveness was analyzed by local adoptive transfer of lymphocytes from two different sources. When spleen cells (SC) from advanced tumor bearing and advanced tumor resected mice were locally transferred into normal recipients, a positive cutaneous delayed hypersensitivity (CDH) reaction was observed. While when peripheral blood lymphocytes (PBL) from the same anergic donors were transferred, no CDH reactivity was elicited. Functional differences between SC and PBL populations are suggested to explain these findings.

Animals↗