Cations decrease specific [3H]-spiroperidol binding in human prefrontal cortex

Ligand binding at many physiologically relevant receptors is regulated by divalent cations. To determine whether [3H]-spiroperidol binding sites in prefrontal cortex might be physiologically relevant receptors, we examined the effect of ions on the binding of this ligand in postmortem human prefrontal cortex. Our results indicate that several cations decreased [3H]-spiroperidol binding in a dose-dependent fashion. Of these, Cd++ and Zn++ were the most able to decrease [3H]-spiroperidol binding with IC50 of 5.5 +/- 2.4 X 10(-6)M and 5.6 +/- 1.1 X 10(-5)M respectively. These findings indicate that [3H]-spiroperidol may bind at physiologically relevant receptors in human prefrontal cortex.     

Influence of testosterone on breathing during sleep

Apneas and hypopneas during sleep occur more frequently in men than women. Disordered breathing is also reported to increase in hypogonadal men following testosterone administration. This suggests a hormonal influence on sleeping respiratory pattern. We therefore studied respiratory rhythm during sleep in 11 hypogonadal males both on and off testosterone-replacement therapy. In four subjects the anatomy (computerized tomography) and airflow resistance of the upper airway were also determined on both occasions. Sleep stage distribution and duration were unchanged following androgen administration. However, both apneas and hypopneas increased significantly during testosterone replacement so that the total number of disordered breathing events (apneas + hypopneas) per hour of sleep rose from 6.4 +/- 2.1 to 15.4 +/- 7.0 (P less than 0.05). This was a highly variable event with some subjects demonstrating large increases in apneas and hypopneas when androgen was replaced, whereas others had little change in respiration during sleep. Upper airway dimensions, on the other hand, were unaffected by testosterone. These results suggest that testosterone contributes to sleep-disordered breathing through mechanisms independent of anatomic changes in the upper airway.     

Regulation of rat ovarian cell growth and steroid secretion

A cultured rat ovarian cell line (31 A-F(2)) was used to study the effect of growth factors (epidermal growth factor [EGF] and fibroblast growth factor [FGF]), a survival factor (ovarian growth factor [OGF]), a hormone (insulin), and an iron-binding protein (transferring) on cell proliferation and steroid production under defined culture conditions. EGF and insulin were shown to be mitogenic (half-maximal response at 0.12 nM and 0.11 muM, respectively) for 31A-F(2) cells incubated in serum-free medium. EGF induced up to three doublings in the cell population, whereas insulin induced an average of one cell population doubling. FGF, OGF, and transferrin were found not to have any prominent effect on cell division when incubated individually with 31A-F(2) cells in serum-free medium. However, a combination of EGF, OGF, insulin, and transferrin stimulated cell division to the same approximate extent as cells incubated in the presence of 5 percent fetal calf serum. EGF or insulin did not significantly affect total cell cholesterol levels (relative to cells incubated in serum-free medium) when incubated individually with 31A-F(2) cells. However, cell cholesterol levels were increased by the addition of OGF (250 percent), FGF (370 percent), or a combination of insulin and EGF (320 percent). Progesterone secretion from 31A-F(2) cells was enhanced by EGF (25 percent), FGF (80 percent), and insulin (115 percent). However, the addition of a mitogenic mixture of EGF, OGF, insulin, and transferrin suppressed progesterone secretion 150 percent) below that of control cultures. These studies have permitted us to determine that EGF and insulin are mitogenic factors that are required for the growth of 31A-F(2) cells and that OGF and transferrin are positive cofactors that enhance growth. Also, additional data suggest that cholesterol and progesterone production in 31A-F(2) cells can be regulated by peptide growth factors and the hormone insulin.     

Tetraene and pentaene leukotrienes: selective production from murine mastocytoma cells after dietary manipulation

A neoplastic mast cell tumor was grown in mice which had been raised since birth on a diet enriched with eicosapentaenoic acid. Intact harvested mastocytoma cells were stimulated with calcium ionophore A23187 to produce lipoxygenase products from the polyunsaturated fatty acids liberated from the cellular membranes. Leukotriene B4, B5, C4, and C5 were isolated and characterized by HPLC retention time, ultraviolet absorption spectrometry and mass spectrometry. The arachidonic acid content of the mast cell tumor lipids was altered from 9.2 to 3.9 mole % while eicosapentaenoic acid increased from 0.5 to 4.5 mole % in response to the fish oil-supplemented diet. The relative amounts of arachidonic and eicosapentaenoic acids (3.9 and 4.5 mole % respectively) were associated with similar amounts of LTB4 and LTB5 synthesized by the cells. These results suggest that the epoxide leukotriene (LIA) derivative can be made efficiently from either arachidonic or eicosapentaenoic acids when both are present in cellular lipids. In contrast, the ratio of LTC4 to LTC5 (10 to 1) indicates that the reaction of LTA with glutathione may be critically dependent upon the structure of the unsaturated fatty acid with the ratio of LTC4/LTB4 (2.0) more than 10 times greater than that (0.16) for LTC5/LTB5.     

Equilibrium constants and photosynthetic enhancement

The linear (Myers) and nonlinear (Joliot-Kok) models of photosynthesis were used to predict enhancement. With an apparent equilibrium constant of 1000 between the two light reactions, both models predict a minimal enhancement of about 1.0. However, with an equilibrium constant of 5, both models predict a minimal enhancement significantly greater than 1.0. Consequently, with an equilibrium constant of 5, neither model can account for the observed enhancement values of 1.0 near 685 nanometers in Chlorella. Also, with an equilibrium constant of 5, enhancement significantly greater than 1.0 is predicted between two short wavelengths or between two long wavelengths; neither is observed.     

Effects of Flashes of Red or Blue Light on the Composition of Starved Chlorella pyrenoidosa

Autotrophically grown cells of Chlorella pyrenoidosa (211-8b) were starved 3 to 4 days in darkness, flashes of blue light, or flashes of red light. The blue flashes were sufficient to maintain the maximal rate of light-stimulated oxygen uptake during short term experiments. However, after 24 hours, the respiration rate in red flashes was equal to, or greater than, the rate in blue flashes. Starvation in darkness reduced the chlorophyll content by 11%, altered the blue absorbance of the nonsaponifiable material only 1 to 2%, and reduced the dry weight by 13%. Starvation in the presence of blue or red flashes reduced the dry weight by an additional 11 or 12% respectively. Protein per unit cell volume was not changed significantly during 3 to 4 days starvation in darkness or in blue flashes, even though dry weight per unit cell volume decreased 13% in darkness and 23% in blue flashes. In contrast, cells starved under red flashes showed a 20% decrease in protein per unit cell volume and a 24% decrease in dry weight per unit cell volume.     

The wood preservative chromated copper arsenate is a substrate for trimethylarsine biosynthesis

The wood preservative chromated copper arsenate (CCA) is a very widely used product. As it contains both copper and arsenic, it is not dissimilar to the pigments Scheele's green and Schweinfurter's green which were found to be biologically convertible to the toxic Gosio gas (B. Gosio, Ber. 30:1024-1026, 1897) later identified by Challenger and co-workers as trimethylarsine (F. Challenger, Adv. Enzymol. 12:429-491, 1951). Thus, it was of interest to determine whether microbiological action on CCA and wood treated with CCA could result in the production of trimethylarsine. We report that the fungus Candida humicola will produce this arsine from dilute solutions of CCA and from wood soaked in CCA.     

Rat liver glutathione S-transferases. Complete nucleotide sequence of a glutathione S-transferase mRNA and the regulation of the Ya, Yb, and Yc mRNAs by 3-methylcholanthrene and phenobarbital

With the use of cDNA probes reverse transcribed from purified glutathione S-transferase mRNA templates, four cDNA clones complementary to transferase mRNAs have been identified and characterized. Two clones, pGTB38 and pGTB34, have cDNA inserts of approximately 950 and 900 base pairs, respectively, and hybridize to a mRNA(s) whose size is approximately 980 nucleotides. In hybrid-select translation experiments, pGTB38 and pGTB34 select mRNAs specific for the Ya and Yc subunits of rat liver glutathione S-transferases. Clone pGTB33, which harbors a truncated cDNA insert, hybrid-selects only the Ya mRNA. All of the clones, pGTB38, pGTB34, and pGTB33, hybrid-select another mRNA which is specific for a polypeptide with an electrophoretic mobility slightly greater than the Ya subunit. The entire nucleotide sequence of the full length clone, pGTB38, has been determined and the complete amino acid sequence of the corresponding polypeptide has been deduced. The mRNA codes for a protein comprising 222 amino acids with Mr = 25,547. We have also identified a cDNA clone complementary to a Yb mRNA of the rat liver glutathione S-transferases. This clone, pGTA/C36, hybrid-selects only Yb mRNA(s) and hybridizes to a mRNA(s) whose size is approximately 1200 nucleotides. Although the Ya, Yb, and Yc mRNAs are elevated coordinately by phenobarbital and 3-methylcholanthrene, the Ya-Yc mRNAs are induced to a much greater extent compared to the Yb mRNA(s). These data suggest that the mRNAs for each transferase isozyme are regulated independently.