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Biomedical subjects

J Orlowski

Publications and source records attributed to J Orlowski.

At least 91 records · Page 5Linked to original sources
PubMed1983

Review of research on endorphins and learning.

Advances in the neurochemistry of learning suggest that many endogenous substances modulate learning processes. Endorphins promote or interfere with learning depending on dose (physiologic versus pharmacologic), task (negative versus positive consequences), and learning stage during which the substance is administered. Endorphins cause amnesia for extraneous details of a task (allowing focusing on main events) and prevent extinction of a learned task (even when forgetting might be adaptive). We have summarized endorphin physiology and review studies of endorphins in animal learning. Implications for the study of human attention and learning disorders are presented.

Animals↗
PubMed1983

Androgen 5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase activities in ventral prostate epithelial and stromal cells from immature and mature rats.

To study androgen-mediated differentiation in the rat ventral prostate, we separated the two principal cell types (epithelial and stromal) derived from prostates of immature and mature rats on two continuous Percoll gradients. Cells were immediately placed in culture medium. Testosterone metabolism by the two prostatic cell types was evaluated using [3H]testosterone and quantifying the formation of 5 alpha-[3H]dihydrotestosterone (5 alpha-DHT) and 5 alpha-[3H]androstane-(3 alpha or 3 beta), 17 beta-diols. In epithelial cells from both immature and mature rat prostates the major testosterone metabolites were 5 alpha-DHT and 5 alpha-androstane-3 alpha, 17 beta-diol. Stromal cells metabolized less testosterone than did the epithelial cells. Differences in the relative levels of the various metabolites were observed for the two age groups. To examine in more detail the changes in testosterone metabolism observed in vitro both types of cells and unfractionated cells from immature and mature rat prostates were assayed for testosterone 5 alpha-reductase (using testosterone as substrate) and 3 alpha-hydroxysteroid dehydrogenase (using 5 alpha-DHT as substrate) activities (expressed as pmol substrate reduced/min per 10(6) cells). In immature rats both 5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase activities were localized in the epithelial cell fraction (17 and 52 respectively); stromal cells showed lower 5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase activity (4 and 4). Relative to epithelial cells from immature rats epithelial cells from mature rats showed a decrease in 5 alpha-reductase (7) and an increase in 3 alpha-hydroxysteroid dehydrogenase (160) activity while stromal 5 alpha-reductase showed little change (3) and 3 alpha-hydroxysteroid dehydrogenase increased to 22.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxysteroid Dehydrogenases↗
PubMed1983

Cathepsin B and prolyl endopeptidase activity in rat peritoneal and alveolar macrophages. Stimulation of peritoneal macrophages by saline lavage.

Cathepsin B and prolyl endopeptidase activity was determined in purified rat pulmonary and peritoneal macrophages and cathepsin B was determined in blood monocytes. The activity of cathepsin B in pulmonary macrophages was more than two times higher than in resident peritoneal macrophages and about eight times higher than in circulating monocytes. The simple process of peritoneal lavage with PBS induced an increase in cathepsin B activity in peritoneal macrophages that by 96 and 144 hr reached those levels observed in pulmonary macrophages. Both pulmonary and peritoneal macrophages contain prolyl endopeptidase activity. Repeated peritoneal lavage induced a significant increase in the activity of the enzyme, but not of the magnitude observed for cathepsin B. The data suggest that the transformation of monocytes into macrophages is associated with a significant increase in cathepsin B activity and that this increase is much greater in pulmonary than in peritoneal macrophages.

Animals↗
PubMed1981

Proteolytic enzymes in bronchopulmonary lavage fluids: cathepsin B-like activity and prolyl endopeptidase.

Two proteolytic enzymes, a cathepsin B-like activity and prolyl endopeptidase activity, were demonstrated in cellular elements and fluids obtained from human bronchopulmonary washings and in fragments of human lung tissue. Model synthetic substrates were used for the determination of enzyme activities. Cathepsin B-like activity was determined with N-benzyloxycarbonyl-L-leucyl-L-leucyl-L-arginyl-2-naphthylamide. The rate of reaction with this substrate was 300 times greater than the rate with alpha-N-benzoyl-DL-arginyl-2-naphthylamide, a substrate commonly used for the determination of cathepsin B activity. Prolyl endopeptidase was determined with N-benzyloxycarbonyl-glycyl-L-prolyl-sulfamethoxazole as the substrate. The two model substrates make possible the determination of enzyme activities in as little as 10 to 50 microliters of lavage fluid. High cathepsin B-like activity and prolyl endopeptidase were generally associated with high macrophage counts in lavage fluids. This observation and the findings that cathepsin B activity is more than 4.5 times higher in normal monocytes than in neutrophils and that prolyl endopeptidase activity could not be detected in normal neutrophils suggest that the enzymes in lavage fluids are mainly derived from macrophages. Large differences in cathepsin B-like activity in certain lavage fluids containing similar macrophage counts suggest the possibility of enzyme induction in these cells. High cathepsin B-like activity and prolyl endopeptidase were also found in lavage fluids after removal of cells by centrifugation. The possibility that these enzymes affect collagen turnover and lung remodeling needs to be explored.

Adult↗
PubMedDate not supplied

Requirements for accurate manometric recording of pharyngeal and esophageal peristaltic pressure waves.

The frequency characteristics and wave form of peristaltic pressure complexes occurring in the pharynx and esophagus of normal subjects were studied. For each of five subjects, five peristaltic waves were selected for analysis from the proximal and distal pharynx as well as the proximal, middle, and distal esophagus. Thus, 25 peristaltic waves were analyzed from each of the five regions studied, giving a total of 125 in all. After digitization of the peristaltic waves, pressure values were entered into a computer algorithm that performed a Fourier transformation to determine frequency content and wave slope. The computer analysis revealed that a frequency response flat to 5 Hz was adequate to record 98% of esophageal peristaltic waves with 98% accuracy. In contrast, recording accuracy up to 48 Hz was needed for high-fidelity recording in the pharynx. Rates of pressure change were substantially greater for pharyngeal peristaltic pressure complexes compared with esophageal peristaltic complexes. The results suggest that appropriately designed infused-catheter systems can readily meet the requirements for accurate recording of peristaltic pressure waves in the esophagus but not in the pharynx. Consequently, different instrumentation, such as an intraluminal strain gauge probe, is needed for accurate manometric recording of pharyngeal peristalsis.

Adult↗