The selective esterification of the 5′-hydroxyl of thymidine

Zusammenfassung Ein einfacher Weg zur selektiven Esterbildung mit der 5-Hydroxylgruppe von Thymidin wird beschrieben. Beispiele: Thymidin-5-phosphat, Thymidin-5-sulfat und Thymidin-5-trichloracetat.     

Brain cyclic nucleotide and energy metabolite responses to subanesthetic and anesthetic concentrations of halothane

Summary Adults rats were exposed to 0.5, 1.0 and 1.5% halothane, delivered in air, for 1 h. Whole brain 3,5-cyclic adenosine monophosphate (cAMP) of halothane-exposed rats showed only a slight increase relative to control values. 3,5-Cyclic guanosine monophosphate (cGMP) was increased significantly in halothane-exposed rats, and the response was directly related to the halothane concentrations. Adenosine triphosphate (ATP) and phosphocreatine (PC) remained unchanged relative to control values. Correspondence of these values to apparent discrepancies in the literature is discussed.Acknowledgments. This research was supported by Public Health Service Grant NS-14355.     

Hydrogen bond catalysis of mononucleotide ethylation supports non-random DNA alkylations by N-ethyl,N-nitrosourea

Summary The axial (ax.) and equatorial (eq.) diastereomeric forms of phosphate triesters resulting from reactions of N-ethyl, N-nitrosourea with 3 cyclic mononucleotides were analyzed by column liquid chromatography (CLC). Evidence is presented that the 2OH group of 3, 5cAMP essentially contributes to the stereoselective eq. alkyl substitution, most probably by hydrogen bonding catalysis. The neighboring group direction of ethylation gives substantial support to non-random DNA alkylations by NEU.We acknowledge the helpful cooperation of Dr Fritz Eckstein, M.P.I. for Exp. Medicine, Göttingen, who determined the³¹P-N.M.R. spectra of the diastereomeric forms of the neutral ethylester of 3, 5 cAMP. This work has been supported by a personal grant to one of us (Sta 131/6 PAN) from the Deutsche Forschungsgemeinschaft. Reprint requests to K.-W. Stahl.     

May K+ ions stimulate the formation of cyclic AMP in the brain independently on their depolarizing action?

Summary The effect of potassium ions on the formation of adenosine 3,5-monophosphate (cAMP) in the rat cerebral cortex in vivo was studied under conditions where development of spreading depression had been blocked by pretreatment of the cerebral cortex by topically applied magnesium ions. A linear relationship between potassium concentrations applied to the cortical surface and levels of cAMP has been found. Moreover, potentiation of the K⁺-effect by magnesium ions has been observed.     

Hotspots of homologous recombination

Homologous recombination occurs at higher than average frequency at and near hotspots. Hotspots are special nucleotide sequences recognized by proteins that promote, directly or indirectly, a rate limiting step of recombination. This review focuses on two well-studied examples, the Chi sites of the bacteriumEscherichia coli and the M26 site of the fission yeastSchizosaccharomyces pombe. Chi, 5 G-C-T-G-G-T-G-G 3, is recognized by the RecBCD enzyme, which nicks the DNA near Chi and produces a 3-ended single-stranded DNA tail; this tail is a potent substrate for homologous pairing by RecA and single-stranded DNA binding proteins. M26, 5 A-T-G-A-C-G-T 3, is recognized by a heterodimeric protein and stimulates, by an as-yet-unknown mechanism, meiotic recombination at and near theade6 gene. Additional hotspots in bacteria, fungi, and mammals enhance recombination directly or indirectly via a variety of mechanisms. Although hotspots are widespread among organisms, the biological role of their localized enhancement of recombination remains a matter of speculation.     

Effect of dibutyryl cyclic AMP and analogs on the rate of contractions of myocytes in culture.

2O, 6N-butyryl, 3', 5'-cyclic monophosphate (dibu cAMP) when added to fetal rat heart cells in culture inhibits myocyte contraction. This inhibition is 100, 84 and 51% complete when the dibu cAMP concentration used is 2, 0.2 and 0.02 mM, respectively. The potency of dibu cAMP derivatives in myocyte contraction inhibition follows the order, dibu cAMP greater than 6N-bu cAMP greater than 2O-bu cAMP = AMP greater than butyrate. The inhibition caused by the first three chemicals is greater than 70%.     

Synthesis of dinucleoside phosphates by reaction of 5′-chloro-5′-deoxynucleosides with nucleotide anions

Zusammenfassung Uridylyl-(3–5)-adenosin und Uridylyl-(3-5)-ionosin wurden durch Umsetzung eines passenden 5-chloro-5-deoxy-2, 3-O-isopropylidene-Nukleosids mit Uridin-3-phosphat synthetisiert.     

A new synthetic method of coumestan derivatives

Zusammenfassung Die Synthese von 7-Hydroxy-5,6-dimethoxybenzofurano[3,2:3,4]coumarin aus 7,2-Dihydroxy-oder 7-Benzyloxy-2-hydroxy-4,5-dimethoxyisoflavon wird beschrieben.     

Fever produced in rabbits by N6, O2′-dibutyryl adenosine 3′, 5′-cyclic monophosphate

Zusammenfassung Die Injektion von N⁶-2-O-Dibutyryl-adenosin-3 5-monophosphat in den lateralen Hirnventrikel von Kaninchen führt zu einer langanhaltenden Fieberreaktion, was vermuten lässt, dass zyklisches Adenosin-35-monophosphat als weiterer Mediator in der Genese des Fiebers fungiert.     

The oxidation of N-2-Fluorenamine and 4-Aminobiphenyl by peracetic acid

Zusammenfassung Im Gegensatz zu neueren Befunden von anderen Autoren finden wir, dass die Oxydation von 2-Fluorenamin oder 4-Aminodiphenyl mit Peressigsäure keine Nitrosoderivate bildet, sondern die Azoverbindungen 2,2-Azoxybisfluoren und 4,4-Azobisdiphenyl.p-Nitroanilin wird zu einem Gemisch oxydiert, aus dem manp, p-Dinitroazoxybenzol undp, p-Dinitroazobenzol durch Chromatographie an Kieselgel isolieren kann.

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Supported by a grant (C-2571) from the National Cancer Institute, U.S. Public Health Service.     

N,N′-di(piperidino-methyl)-3,3′-diindolyl-methane (DIM), a diindolylmethane derivative of neuroplegic action

Zusammenfassung Ein neues Diindolyl-methan-derivat, das N, N-di(piperidino-methyl)-3, 3-diindolyl-methan, wurde synthetisiert; es verursacht im Tierversuch schon in Dosen von 3–5 mg/kg einen langanhaltenden zentralen Depressoreffekt.     

A2 adenosine receptors in human glomerular mesangial cells

A₂ adenosine receptors were characterized in human glomerular mesangial cells using [³H] 5-N-ethylcarboxamidoadenosine (NECA) as a tracer. There was a single group of receptor sites with a K_D of 184 nM, and a number of sites of 317 fmol/mg of cell protein. Adenosine agonists increased 5-nucleotidase activity via A₂ receptor stimulation. The specific A₂ agonist-NECA, at 0.1 and 1 m, was a potent inhibitor of DNA synthesis.     

Über die Beeinflussung des Serumkomplementes durch Vitamin-K-Mangel beim Küken

Summary In vitamin K deficient chicken the serum complement (C) level is significantly decreased, as compared with normal animals, due to a lower level of its component C1. Administration of vitamin K₁ for three days did not restore its titer although the prolonged blood clotting time became normal. The results thus indicate a considerably slower resynthesis of the complement factor C1 than of prothrombin.     

Microbiological assay of cyclic 3′, 5′-AMP

Zusammenfassung Es wird ein mikrobiologisches Testverfahren beschrieben, mit dem sehr geringe Mengen von zyklischem Adenosin 3, 5-monophosphat quantitativ nachgewiesen werden können.     

Epidermal growth factor stimulates proliferation of rat hepatoma cells producing α-fetoprotein

Summary Epidermal growth factor stimulated both [³H]thymidine uptake and proliferation of rat AH66 hepatoma cells. However, the increase in cell number was not accompanied by a proportional increase in the levels of -fetoprotein of the culture media. The effects of EGF on the cell proliferation were antagonized by N⁶, O²-dibutyryl cAMP.     

Polyhydroxylated metabolites oftrans-stilbene in the rat

Zusammenfassung Nach Eingabe vontrans-Stilben bei Ratten wurden die grössten Mengen im Harn als 3,4,4-Trihydroxystilben, 3,4,4-Trihydroxybibenzyl und 3,3, 4,4-Tetrahydroxybibenzyl nachgewiesen. Die Bibenzylderivate werden nachscheinlich nach Ausscheidung in der Galle von Darmbakterien metabolisiert.     

Arabinose nucleoside triphosphates are no inhibitors for DNA-dependent RNA polymerases

Summary 1--d-arabinofuranosylcytosine-5-triphosphate and 9--d-arabinofuranosyladenosine-5-triphosphate were found to have no inhibitory potency for both mammalian DNA-dependent RNA polymerase II andE. coli DNA-dependent RNA polymerase.     

The terminal transformation of immune complement; comparison of human and guinea-pig C′3

Zusammenfassung Mit Meerschweinchen-Komplement sensibilisierte Schaferythrocyten (EAC1,4,2) wurden einerseits mit Meerschweinchen-, andererseits mit menschlichem C3 in Intermediärform (E^*) gebracht. Sie wurden im ersten Fall rascher lysiert, als im zweiten Fall. Es wird vermutet, dass hauptsächlich die EAC1,4,2 + C3-Reaktion für die unterschiedliche Wirkung von Meerschweinchen- und menschlichem Komplement in der Terminalphase der Hämolyse verantwortlich ist.     

A new synthesis of dehydromunduserone

Zusammenfassung Eine einfache Synthese von Dehydromunduseron aus 7,2,4,5-Tetramethoxy-isoflavon wird beschrieben.     

The effect of cyclic N-2-O-dibutyryl-adenosine-3′, 5′-monophosphate on neuromuscular transmission and concentration of glycogen in the isolated phrenic nerve-diaphragm preparation of the rat

Résumé Le dérivé dibutyrique du 3, 5-AMP cyclique potentialise les contractions du diaphragme provoquées par stimulation électrique indirecte, alors que l'application du 3,5-AMP cyclique n'a pas un tel effet. D'autre part, ce dérivé diminue le taux de glycogène du diaphragme, ce qui n'est pas le cas pour le 3,5-AMP cyclique.