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Biomedical subjects

L Schreiber

Publications and source records attributed to L Schreiber.

46 records · Page 3Linked to original sources
PubMed1991

Effect of acidosis on lipid peroxidation in brain slices.

Acidification of the incubation medium markedly increased lipid peroxidation of cortical brain slices. Lactic acidosis caused a more extensive lipid peroxidation than did phosphoric acidosis (+35% at pH 6 and +81% at pH 5), probably due to the rapid diffusion of the protonated form of lactic acid across cell membranes. These results support the hypothesis that free radical mechanisms may be involved in the cytotoxicity of acidosis.

Acidosis↗
PubMed1991

Analysis of thymic stromal cell subpopulations grown in vitro on extracellular matrix in defined medium. III. Growth conditions of human thymic epithelial cells and immunomodulatory activities in their culture supernatant.

We report here on a new approach to the cultivation of human thymic epithelial (HTE) cells, which apparently allows more faithful preservation of cell function. This approach, previously developed by us for mouse thymic epithelial (MTE) cells, is based on the use of culture plates coated with extracellular matrix (ECM), and on the use of serum-free, growth factor-supplemented medium. The nutritional requirements of HTE and MTE are somewhat different. Although both are critically dependent on ECM and insulin, they differ in their dependency on other growth factors: selenium and transferrin are much more important for HTE cells, whereas epidermal growth factor and hydrocortisone play a more essential role in MTE cultures. The epithelial nature of the cultured cells is indicated by positive staining with anti-keratin antibodies and by the presence of desmosomes and tonofilaments. The ultrastructural appearance of the cells further suggests high metabolic and secretory activities, not usually found in corresponding cell lines. The culture supernatant (CS) of HTE cells exhibited a strong enhancing effect on thymocyte response to Con A stimulation, as measured by cell proliferation and lymphokine production. The effect was observed on both human and mouse thymocytes, but was much stronger in the homologous combination. Thymic factors tested in parallel did not have such a differential effect. The dose-effect relationships were in the form of a bell-shaped curve, with fivefold enhancement of response at the peak and a measurable effect even with 1:1000 dilution, when human thymocytes were used. The responding thymocytes were those which do not bind peanut agglutinin and are resistant to hydrocortisone. The culture system described here may have advantages for the in vitro study of thymic stromal cell function.

Animals↗
PubMed1990

Microinjection of cocaine into the nucleus accumbens elicits locomotor activation in the rat.

Cocaine is believed to exert its psychostimulant effects through activation of the mesocorticolimbic system. Although the nucleus accumbens, in particular, has been hypothesized as the site of action of cocaine's stimulating effects, there is no direct evidence that microinjection of cocaine into this region produces behavioral activation. The present experiments investigated the locomotor response to microinjection of cocaine (0, 10, 30, 100 micrograms/0.5 microliter) into the nucleus accumbens in rats. Cocaine elicited a pronounced, dose-dependent motor activation of approximately 60 min duration. This stimulant effect was blocked by prior administration of a dopamine (DA) receptor antagonist, cis-flupenthixol. The response to cocaine was differentiated from nucleus accumbens microinjections of procaine and lidocaine, compounds that have potent local anesthetic effects but little affinity for the dopamine-uptake site. Neither procaine nor lidocaine (0, 10, 30, 100 micrograms/0.5 microliter) had any overall effect, although activity was somewhat decreased in the initial part of the test session and increased at the end, relative to control activity. Cocaine injected into the anterior dorsal or ventrolateral striatum (100 micrograms) also increased motor activity; procaine and lidocaine had no effect. Cocaine injected into the ventrolateral striatum significantly increased stereotypy. The amplitude of motor activation following cocaine injection into nucleus accumbens was much greater than that elicited at the other striatal sites. Further, observation of the time course of motor activation following cocaine injection into the anterior dorsal and ventrolateral striatum suggested that the motor effect was due to diffusion, most likely to the nucleus accumbens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Rapid clearance of the lupus antigen Sm is delayed by autoantibody: a possible mechanism of autoimmunity perpetuation.

Sm ribonucleoprotein complex was immunopurified and labelled with 125I. After i.v. injection into normal mice 125I-Sm was cleared with a half life of less than 3 min, mainly to the liver (54% at 15 min). With time there was a progressive reduction in liver uptake (13.3% at 1 h), and this was associated with the appearance of increasing amounts of trichloroacetic acid soluble 125I in serum, suggesting complete Sm catabolism. Injection of 125I-Sm as a preformed immune complex with human anti-Sm antibody was associated with slower antigen removal from the circulation (half life 15 min), more gradual liver uptake (27% at 1 hr), and less degradation products in the serum than after injection of antigen alone. These data suggest that release of 125I-Sm into the circulation is followed by specific organ uptake and antigen degradation. In the form of an immune complex, the rapid removal mechanism is impaired, and antigen persists in the circulation in an undegraded form. Simultaneous production of anti-Sm antibody and Sm antigen release following tissue destruction could lead to amplification of any primed immune response as a result of autoantigen drive in systemic lupus erythematosus.

Animals↗
PubMedDate not supplied

Transvaginal sonographic diagnosis of sigmoid diverticulitis.

The development of the transvaginal technique has allowed for high-resolution, detailed evaluation of the female pelvis. Although not previously emphasized, gut pathology can also be recognized with this technique. We report two cases of sigmoid diverticulitis which were prospectively diagnosed using endovaginal sonography. In both patients, pelvic sonogram was the first imaging study performed for evaluation of nonspecific abdominal pain.

Aged↗