Alterations of prostate biomarker expression and testosterone utilization in human LNCaP prostatic carcinoma cells by garlic-derived S-allylmercaptocysteine.

BACKGROUND: This study determined the effects of S-allylmercaptocysteine (SAMC), a phytoconstituent from garlic, on the expression of androgen-responsive biomarkers, prostate specific antigen (PSA), and prostate specific membrane antigen (PSMA), in human prostatic carcinoma cells (LNCaP). METHODS: Secretion of PSA was determined as well as the activity of PSMA measured as a function of its ability to hydrolyze poly-gamma-glutamated folate and N-acetylaspartylglutamate (NAAG). Folate hydrolase capacity was also determined in SAMC-treated cells grown in charcoal stripped fetal calf serum (CS-FCS). In addition, testosterone disappearance was measured from culture media of SAMC-treated LNCaP and PC-3 cells as well as from cell free lysates. RESULTS: PSA secretions were significantly decreased compared to control values at 1 day (8.4 +/- 2.6 vs. 18.9 +/- 1.7, P < 0.01), 4 days (18.9 +/- 5.3 vs. 73.8 +/- 4. 4, P < 0.001), and 6 days (35.6 +/- 2.1 vs. 96.5 +/- 17.9 ng/10(5) cells, P < 0.01; mean +/- SD). By contrast, PSMA activity measured as either folate hydrolase or NAAG dipeptidase (NAALADase) activity increased in cells treated with SAMC. PSMA-folate hydrolase activity in SAMC-treated cells grown in CS-FCS increased beyond that observed in cells grown in CS-FCS alone. Pre-exposure of LNCaP cells to SAMC resulted in enhanced rate of testosterone disappearance from culture media at 6 hr (P < 0.01) and at 48 hr (P < 0.001) compared to media from cells not previously exposed to SAMC. Results similar to these were also observed in androgen-independent PC-3 cells treated with SAMC. In lysates of SAMC-treated LNCaP cells, the rate of testosterone catabolism was twice that from phosphate buffered saline (PBS)-treated cells. SAMC-treated LNCaP cells grown in media supplemented with testosterone temporarily exhibited enhanced growth over a 2 day period but cell numbers declined later to levels similar to those of SAMC treatment. CONCLUSIONS: These results show that SAMC exhibits differential effects on recognized biomarkers for LNCaP cells similar to those produced by androgen deprivation and strongly suggests that this effect may be mediated, in part, by diminishing the trophic effects of testosterone, likely by converting it to metabolites less reactive toward androgen receptors.

[Coronary angiography and change in antioxidative status]. / Koronarangiographie und Veränderung des antioxidativen Status.

PATIENTS AND METHODS: In a prospective study in 53 patients with stable angina pectoris symptoms the antioxidant status (glutathione peroxidase, glutathione, superoxid dismutase, malondialdehyde and selenium in serum and whole blood) was determined before and 4 to 6 hours after coronary angiography. According to the results of the coronary angiography the patients were classified in a group with "severe" (n = 16) and another with "moderate" coronary alterations. RESULTS: In both groups there was a significant reduction of selenium in serum and whole blood. The enzymes glutathione peroxidase and superoxide dismutase as well as glutathione and malondialdehyde changed only slightly. CONCLUSION: These results can be the cause of an increase of the formation of free radicals during coronary reperfusion (PTCA, implantation of stents in the group with "severe" coronary alterations) but could also be seen as a sign of formation of radicals by the method itself (in patients with "moderate" coronary alterations). Further investigations are indicated. Furthermore the amelioration of the antioxidant status of the organism by scavenger substances (vitamins A, B, C and selenium) should be discussed.

[Sex hormones and antioxidant status]. / Sexualhormone und Antioxidanzienstatus.

Physiologically, an influence of sex steroids on the antioxidative capacity can be seen at least as a short-term effect. First of all the steroid effects are due to the estrogen component rather than the progestin component. The antioxidative potential of natural estrogens is several times higher than that of vitamin E. Long-term studies should be performed to verify this in perimenopausal hormone replacement.

NMDA receptors in the midbrain periaqueductal gray mediate hypothalamically evoked hissing behavior in the cat.

The present study was designed to test the hypothesis that the descending pathway from the medial hypothalamus to the dorsal periaqueductal gray (PAG) is critical for the expression of defensive rage behavior in the cat and utilizes excitatory amino acids as a neurotransmitter. In the first phase of the study, monopolar stimulating electrodes were implanted into the medial hypothalamus from which defensive rage behavior could be elicited by electrical stimulation. For the entire study, the hissing response was used as a measure of defensive rage behavior. Cannula electrodes were implanted into the PAG from which defensive rage sites could be identified and were later used for microinfusion of the NMDA receptor antagonist, DL-2-amino-7-phosphoheptanoic acid (AP-7), into behaviorally identified sites within the PAG. Initially, intracerbral microinjections of the NMDA receptor antagonist, AP-7 (0.2, 2.0 nmol), which were placed directly into sites within the PAG from which defensive rage had been elicited, blocked the occurrence of hypothalamic hissing. Microinjections of similar doses of AP-7 into the PAG also blocked the facilitatory effects of medial hypothalamic stimulation upon hissing behavior elicited from the PAG. However, microinjections of 2 nmol into the PAG had no effect upon hissing that was also elicited from the region of the injection site. This finding indicates that AP-7 selectively blocks hissing elicited from the medial hypothalamus and that the suppressive effects of AP-7 cannot be the result of anesthetic or other nonselective properties of the drug. The next phase of the study, which employed immunohistochemical, receptor autoradiographic techniques, identified NMDA receptors to be present in highest concentrations in the dorsolateral aspect of the PAG where defensive rage is typically elicited. The final phase of the study, which employed a combination of retrograde labeling procedures following microinjections of Fluoro-Gold into defensive rage sites in the dorsal PAG and the immunocytochemical labeling of glutamatergic neurons, identified large numbers of neurons in the medial hypothalamus that were labeled positively for both Fluoro-Gold and glutamate. The overall findings of this study support the hypothesis that descending fibers of the medial hypothalamus that supply the dorsal aspect of the PAG mediate defensive rage behavior and utilize excitatory amino acids that act upon NMDA receptors within the dorsal PAG.

The cAMP-binding ectoprotein from Saccharomyces cerevisiae is membrane-anchored by glycosyl-phosphatidylinositol.

Saccharomyces cerevisiae contains an amphiphilic cAMP-binding glycoprotein at the outer face of the plasma membrane (M(r) = 54,000). It is converted to a hydrophilic form by treatment with glycosyl-phosphatidylinositol-specific phospholipases C and D (GPI-PLC/D), suggesting membrane anchorage by a covalently bound glycolipid. Determination of the constituents of the purified anchor by gas-liquid chromatography and amino acid analysis reveals the presence of glycerol, myo-inositol, glucosamine, galactose, mannose, ethanolamine, and asparagine (as the carboxyl-terminal amino acid of the Pronase-digested protein to which the anchor is attached). Complementary results are obtained by metabolic labeling, indicating that fatty acids and phosphorus are additional anchor constituents. The phosphorus is resistant to alkaline phosphatase, whereas approximately half is lost from the protein after treatment with GPI-PLD or nitrous acid, and all is removed by aqueous HF indicating the presence of two phosphodiester bonds. Inhibition of N-glycosylation by tunicamycin or removal of protein-bound glycan chains by N-glycanase or Pronase does not abolish radiolabeling of the anchor structure by any of the above compounds. Analysis of the products obtained after sequential enzymic and chemical degradation of the anchor agrees with the arrangement of constituents in GPIs from higher eucaryotes. Evidence for anchorage of the yeast cAMP-binding protein by a GPI anchor is strengthened additionally by the reactivity of the GPI-PLC-cleaved anchor with antibodies directed against the cross-reacting determinant of trypanosomal variant surface glycoproteins.

Proline metabolism in N2-fixing root nodules: energy transfer and regulation of purine synthesis.

N2-fixing root nodules of soybean (Glycine max L. Merr.) convert atmospheric N2 to ammonia(um) in an energy-intensive enzymatic reaction. These nodules synthesize large quantities of purines because nitrogen fixed by bacteria contained within this tissue is transferred to the shoots in the form of ureides, which are degradation products of purines. In animal systems, it has been proposed that proline biosynthesis by pyrroline-5-carboxylate reductase (P5CR) is used to generate the NADP+ required for the synthesis of the purine precursor ribose 5-phosphate. We have examined the levels, properties, and location of P5CR and proline dehydrogenase (ProDH) in soybean nodules. Nodule P5CR was found in the plant cytosol. Its activity was substantially higher than that reported for other animal and plant tissues and is 4-fold higher than in pea (Pisum sativum) nodules (which export amides). The Km for NADPH was lower by a factor of 25 than the Km for NADH, while the Vmax with NADPH was one-third of that with NADH. P5CR activity was diminished by NADP+ but not by proline. These characteristics are consistent with a role for P5CR in supporting nodule purine biosynthesis rather than in producing proline for incorporation into protein. ProDH activity was divided between the bacteroids and plant cytosol, but less than 2% was in the mitochondria-rich fractions. The specific activity of ProDH in soybean nodule bacteroids was comparable to that in rat liver mitochondria. In addition, we propose that some of the proline synthesized in the plant cytosol by P5CR is catabolized within the bacteroids by ProDH and that this represents a novel mechanism for transferring energy from the plant to its endosymbiont.