Na+/K+-ATPase Inhibition Partially Mimics the Ethanol-Induced Increase of the Golgi Cell-Dependent Component of the Tonic GABAergic Current in Rat Cerebellar Granule Cells

Cerebellar granule cells (CGNs) are one of many neurons that express phasic and tonic GABAergic conductances. Although it is well established that Golgi cells (GoCs) mediate phasic GABAergic currents in CGNs, their role in mediating tonic currents in CGNs (CGN-I_tonic) is controversial. Earlier studies suggested that GoCs mediate a component of CGN-I_tonic that is present only in preparations from immature rodents. However, more recent studies have detected a GoC-dependent component of CGN-I_tonic in preparations of mature rodents. In addition, acute exposure to ethanol was shown to potentiate the GoC component of CGN-I_tonic and to induce a parallel increase in spontaneous inhibitory postsynaptic current frequency at CGNs. Here, we tested the hypothesis that these effects of ethanol on GABAergic transmission in CGNs are mediated by inhibition of the Na⁺/K⁺-ATPase. We used whole-cell patch-clamp electrophysiology techniques in cerebellar slices of male rats (postnatal day 23–30). Under these conditions, we reliably detected a GoC-dependent component of CGN-I_tonic that could be blocked with tetrodotoxin. Further analysis revealed a positive correlation between basal sIPSC frequency and the magnitude of the GoC-dependent component of CGN-I_tonic. Inhibition of the Na⁺/K⁺-ATPase with a submaximal concentration of ouabain partially mimicked the ethanol-induced potentiation of both phasic and tonic GABAergic currents in CGNs. Modeling studies suggest that selective inhibition of the Na⁺/K⁺-ATPase in GoCs can, in part, explain these effects of ethanol. These findings establish a novel mechanism of action of ethanol on GABAergic transmission in the central nervous system.     

The calcium-binding property of equine lysozyme

It was found that equine lysozyme binds one Ca2+. It was eluted with equimolar Ca2+ from a Bio-Gel P-4 column. Human lysozyme did not behave similarly. Equine lysozyme is concluded to be a calcium metallo-protein like alpha-lactalbumin, which is a homologue of hen egg white lysozyme.     

Inhibition of RNA synthesis in embryo of Xenopus laevis by protease inhibitor

We have studied the role of proteases during the development of Xenopus laevis embryos with the aid of protease inhibitors. The activity of proteases was found to be only minimal in the unfertilized egg and during the initiation of development, but activity began to increase at the morula stage. When the activity of proteases was inhibited by antipain, an inhibitor of endopeptidase activity, RNA synthesis in the embryo was inhibited. To examine the relationship between the inhibitory effect of antipain on protease activity and its effect on RNA synthesis, antipain was reduced with NaBH4 to inactivate its protease inhibitory activity. The reduced antipain did not inhibit RNA synthesis in the embryo. Antipain effectively inhibited synthesis of both rRNA and poly(A)+RNA but not 4S RNA. We therefore suggest that protease activity plays an important role in the initiation and/or continuation of RNA synthesis.     

Loss of androgen dependency with preservation of functional androgen receptors in androgen-dependent mouse tumor (Shionogi Carcinoma 115).

Shionogi Carcinoma 115 (SC 115) is an androgen-dependent mouse tumor. Chiba Subline 2 (CS 2) is an androgen-independent subline derived from SC 115. CS 2 contains androgen receptors (AR), but is refractory to androgen and does not exhibit androgen-related responses which are observed in SC 115. In the present study the structure and function of AR in SC 115 and CS 2 are examined using cloned cells. There were no gross rearrangements or deletions in the AR genes of these cell lines when compared by Southern blot analysis with the AR gene in the mouse seminal vesicle. SC 115 and CS 2 expressed AR mRNA of normal size. When the cDNA containing DNA- and androgen-binding domains of the AR genes of both cell lines were amplified by polymerase chain reaction, no mutations were found in these regions. SC 115 and CS 2 were transfected with a plasmid containing a long terminal repeat of mouse mammary tumor virus linked to the chloramphenicol acetyltransferase (CAT) gene. Androgen stimulation of these transfectants resulted in equal elevation of CAT activity. These results indicated that the androgen-independent CS 2 contained functionally normal AR which were identical to those in the androgen-dependent parent tumor.     

Characteristics of progestin binder in hypertrophic human prostate

The human prostate contains a protein which binds with progesterone in a high affinity and low capacity fashion. Characteristics of the progestin-binding protein in the prostate have been disputable; whether it is progesterone receptor or not. Therefore, the characteristics of the progestin binder in the benign hypertrophic human prostate was examined in the present study. After photoaffinity labeling with 3H-R 5020, the binder in the prostate migrated to the site of 42K on polyacrylamide gel electrophoresis under denaturing conditions, and the mobility was apparently different from that of the progesterone receptor in the human uterine endometrium. There was no protein in the prostate immunoreacted with a monoclonal antibody raised against the human progesterone receptor. It was concluded that the progestin-binding protein in the human prostate was different from the progesterone receptor observed in the female human organs.     

Identification with Monoclonal Antibodies of a Second Antigenic Domain on Avena Phytochrome that Changes upon Its Photoconversion

An enzyme-linked immunosorbent assay that revealed an antigenic difference between the red-absorbing and far-red-absorbing forms of phytochrome (Pr and Pfr, respectively) near its amino terminus (Cordonnier M-M, H Greppin, LH Pratt 1985 Biochemistry 24: 3246-3253) was used to screen eight additional monoclonal antibodies directed to phytochrome from etiolated oats. While six of these antibodies detected Pr and Pfr with equal affinity, two of them, designated Oat-9 and Oat-16, bound to Pfr 1.6 to 2.3 times better than to Pr. Competitive enzyme-linked immunosorbent assays indicate (a) that Oat-9 and Oat-16 probably bind to the same domain on phytochrome and (b) that this domain is at least 3.5 nanometers away from the epitope near its amino terminus that was shown earlier to change upon phototransformation. Neither the absorbance spectra of Pr and Pfr, nor the rate of dark reversion of Pfr to Pr, was influenced by the presence of Oat-9. Immunoblotting of sodium dodecyl sulfate polyacrylamide gels after electrophoretic separation of phytochrome fragments obtained by endogenous proteolytic digestion indicates that Oat-16 binds to an epitope located on the chromophore half of this chromoprotein. The observation that the epitope recognized by Oat-9 and Oat-16 is also present on at least some of the immunochemically distinct phytochrome that is obtained from green oat shoots (Shimazaki Y, LH Pratt 1985 Planta 164: 333-344), together with the evidence that this epitope undergoes a change upon photoransformation, indicates that it may play an important role in phytochrome function.     

Immunochemical detection with rabbit polyclonal and mouse monoclonal antibodies of different pools of phytochrome from etiolated and green Avena shoots

While two monoclonal antibodies directed to phytochrome from etiolated oat (Avena sativa L.) shoots can precipitate up to about 30% of the photoreversible phytochrome isolated from green oat shoots, most precipitate little or none at all. These results are consistent with a report by J.G. Tokuhisa and P.H. Quail (1983, Plant Physiol. 72, Suppl., 85), according to which polyclonal rabbit antibodies directed to phytochrome from etiolated oat shoots bind only a small fraction of the phytochrome obtained from green oat shoots. The immunoprecipitation data reported here indicate that essentially all phytochrome isolated from green oat shoots is distinct from that obtained from etiolated oat shoots. The data indicate further that phytochrome from green oat shoots might itself be composed of two or more immunochemically distinct populations, each of which is distinct from phytochrome from etiolated shoots. Phytochrome isolated from light-grown, but norflurazon-bleached oat shoots is like that isolated from green oat shoots. When light-grown, green oat seedlings are kept in darkness for 48 h, however, much, if not all, of the phytochrome that reaccumulates is like that from etiolated oat shoots. Neither modification during purification from green oat shoots of phytochrome like that from etiolated oat shoots, nor non-specific interference by substances in extracts of green oat shoots, can explain the inability of antibodies to recognize phytochrome isolated from green oat shoots. Immunopurified polyclonal rabbit antibodies to phytochrome from etiolated pea (Pisum sativum L.). shoots precipitate more than 95% of the photoreversible phytochrome obtained from etiolated pea shoots, while no more than 75% of the pigment is precipitated when phytochrome is isolated from green pea shoots. These data indicate in preliminary fashion that an immunochemically unique pool of phytochrome might also be present in extracts of green pea shoots.Abbreviation ELISA enzyme-linked immunosorbent assay - mU milliunit - Pfr far-red-absorbing form of phytochrome - Pr red-absorbing form of phytochrome     

Binding of mibolerone to androgen receptor of benign hypertrophic human prostate. Comparison with R1881

The binding nature of mibolerone in cytosols and nuclear extracts from hypertrophic human prostate was examined in comparison with that of R 1881. The binding of mibolerone in the cytosol and nuclear extract was single and of high affinity when evaluated by the method of Scatchard (1949). Binding of mibolerone with testosterone-binding globulin was not detected. The sedimentation coefficients of the binder for mibolerone in the cytosol and nuclear extract were 10.6 S and 3.6 S, respectively. When triamcinolone acetonide was induced in the binding medium, inhibition of mibolerone binding in the cytosol by testosterone and dihydrotestosterone was potentiated and this may imply that the binding observed in the presence of triamcinolone acetonide was responsible for the binding of the androgen receptor. In the nuclear extract, the binding was attributable mainly to the androgen receptor irrespective of the presence or absence of triamcinolone acetonide. These properties of the binding observed in the hypertrophic human prostate were almost same as those of the binding with R 1881. Although maximum binding sites measured using mibolerone were correlated with those using R 1881 in the cytosols as well as in the nuclear extracts, the values obtained with mibolerone were slightly greater than those with R 1881. Thus, mibolerone seems to be a suitable ligand for measuring the androgen receptor, but when compared with R 1881 no special merits in using mibolerone were detected.     

Immunoprecipitation of phytochrome from green Avena by rabbit antisera to phytochrome from etiolated Avena

Thirty-nine antiserum preparations from eight rabbits were screened for their ability to precipitate the immunochemically distinct phytochrome that is obtained from green oat (Avena sativa L.) shoots. The antisera were obtained from rabbits immunized with either proteolytically degraded, but still photoreversible, 60-kDa (kilodalton) phytochrome, or approx. 120-kDa phytochrome, both of which were purified from etiolated oat shoots. The ability of these antisera to precipitate phytochrome from green oats was independent of the size of phytochrome used for immunization. While crude antisera immunoprecipitated as much as 80% of the phytochrome isolated from green oat shoots, antibodies immunopurified from these sera with a column of highly purified, approx. 120-kDa phytochrome from etiolated oats precipitated no more than about 5–10%.Abbreviations kDa kilodalton - mU milliunit     

Synthesis of New Bis(pyrazolo[1,5-a]pyrimidines) Linked to Different Spacers as Potential MurB Inhibitors

An efficient protocol was adopted to efficiently prepare three new series of bis(pyrazolo[1,5-a]pyrimidines) linked to different spacers. The new bis(pyrazolo[1,5-a]pyrimidines) were prepared in 80–90 % yields by reacting the respective bis(enaminones) and 4-(4-substituted benzyl)-1H-pyrazole-3,5-diamines in pyridine at reflux temperature for 5–7 h. The new products showed a wide spectrum of antibacterial activity against six different bacterial strains. In general, propane- and butane-linked bis(pyrazolo[1,5-a]pyrimidines), which are attached to 3-(4-methyl- or 4-methoxybenzyl) units, had the best antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values up to 2.5 and 5.1 μM, respectively. Additionally, the previous products demonstrated promising MurB inhibitory activity with IC₅₀ values up to 7.2 μM.