Sympathetic control of nasal blood flow in the rat mediated by alpha(1)-adrenoceptors.

Experiments were undertaken, using laser-Doppler flowmetry, to determine the nature of adrenoceptors mediating sympathetic nerve evoked nasal vasoconstrictor responses in anesthetized rats. Presence of sympathetic tone was confirmed by a large (330%) increase of nasal blood flow following section of the ipsilateral preganglionic cervical sympathetic nerve. Electrical nerve stimulation produced reproducible, frequency-related nasal vasoconstrictor responses with near maximal response, observed at less than 10 Hz.

Recognition of 2'-deoxy-l-ribonucleoside 5'-triphosphates by human telomerase.

Telomerase is classified as one of the reverse transcriptases (RTs). To clarify whether l-enantiomers of natural 2'-deoxyribonucleoside 5'-triphosphates (dNTPs) are recognized by human telomerase, a quantitative telomerase assay based on the "stretch PCR" method was developed and used for kinetic analysis of the inhibitory effects of these compounds on the enzyme. Among the four l-enantiomers of dNTPs, l-dTTP and l-dGTP inhibited telomerase activity and the others showed slight or no inhibitory effect.

Enzyme cytochemical localization of sarcosine oxidase activity in the liver and kidney of several mammals.

We investigated the enzyme cytochemical localization of sarcosine oxidase (SOX) in the liver and kidney of several mammals using a cerium technique. First we measured the enzyme activities in the liver and kidney of several mammals and in several organs of mice. The highest activity was found in the Chinese hamster, followed by the mouse.

Inhibitory effects of of L-2'-deoxyguanosine 5'-triphosphate (L-dGTP) and L-2'-deoxythymidine 5'-triphosphate (L-dTTP) on human telomerase.

Telomerase, which synthesizes telomeric DNA in eukaryotic cells, is classified as a reverse transcriptase. To clarify the recognition of 2'-deoxyribonucleoside 5'-triphosphate (dNTP) chirality by telomerase, we studied the inhibitory effects of L-dGTP on HeLa cell telomerase activity using a quantitative 'stretch PCR' assay. L-dGTP had a weakly inhibitory effect (IC50 = 200 microM) in the presence of 10 microM dGTP.

Sympathetic vasodilation in the rat anterior choroid mediated by beta(1)-adrenoceptors.

Electrical stimulation of the preganglionic superior cervical nerve produced a frequency-dependent vasoconstrictor response in the anterior choroidal blood vessels of the eye of anesthetized rats. Systemic administration of phentolamine (5 mg kg(-1)) reversed the vasoconstriction to a vasodilator response. This sympathetic-evoked vasodilation was not antagonized by inhibition of nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME) (20 mg kg(-1)) or by inhibition of cyclo-oxygenase with indomethacin (20 mg kg(-1)).

Structural and dynamic properties of crystalline and amorphous phases in raffinose-water mixtures.

Purpose: To obtain an improved characterisation of the raffinose-water solid-solid and solid-liquid state diagram, and to study the thermophysical behaviour of the solid amorphous phase. This information is expected to shed light on the potential of raffinose as a pharmaceutical excipient, for stabilising labile preparations at high temperatures.

Methods: X-ray diffraction, scanning electron microscopy, polarised-light microscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were applied to study raffinose pentahydrate and its behaviour during progressive dehydration.

Iron dependence of tryptophan hydroxylase activity in RBL2H3 cells and its manipulation by chelators.

Tryptophan hydroxylase requires Fe2+ for in vitro enzyme activity. In this study, the intracellular activity of tryptophan hydroxylase was assessed by applying 3-hydroxybenzylhydrazine (NSD-1015), an inhibitor of aromatic l-amino acid decarboxylase, to monolayer cultures of RBL2H3 cells, a serotonin producing mast cell line. The effect of manipulating intracellular 'free' iron levels on enzyme activity was analyzed by administration of iron chelators.

Sympathetic vasoconstriction in the rat anterior choroid is mediated by alpha1-adrenoceptors.

These experiments were undertaken in an attempt to use laser-Doppler flowmetry to measure anterior choroidal blood flow in the anesthetized rat and to study the mechanism by which sympathetic nerve stimulation might produce vasoconstriction in this vascular bed. Electrical stimulation of the preganglionic cervical sympathetic nerve produced reproducible, frequency-related ocular vasoconstrictor responses with maximal vasoconstriction seen at about 32 Hz. Ocular vasoconstrictor responses were blocked by intravenous treatment with the nonselective alpha-adrenoceptor antagonists, phentolamine (5 mg kg(-1)) and phenoxybenzamine (2 mg kg(-1)), as well as with the selective alpha1-adrenoceptor antagonist, prazosin (0.

Synthetic nucleosides and nucleotides. 40. Selective inhibition of eukaryotic DNA polymerase alpha by 9-(beta-D-arabinofuranosyl)-2-(p-n-butylanilino) adenine 5'-triphosphate (BuAaraATP) and its 2'-up azido analog: synthesis and enzymatic evaluations.

Starting from 2',3',5'-tri-O-acetyl-2-iodoadenosine, 9-(beta-D-arabinofuranosyl)-2-(p-n-butylanilino)adenine and its 2'(S)-azido counterparts were synthesized in seven steps. These exhibited only moderate growth-inhibitory effects against mouse leukemic P388 cells (IC50 = 13-24 microM), although 5'-triphosphate derivatives showed strong and selective inhibitory action on calf thymus DNA polymerase alpha, but not on beta- and epsilon-polymerases from eukaryotes.

Chiral discrimination of 2'-deoxy-L-cytidine and L-nucleotides by mouse deoxycytidine kinase: low stereospecificities for substrates and effectors.

The effects of four kinds of 2'-deoxy-L-nucleoside 5'-triphosphates and L-ATP, which are enantiomers of natural D-dNTPs and D-ATP, on deoxycytidine kinase (dCK) partially purified from mouse leukemic P388 cells were investigated. Only L-dCTP did not act as a phosphate donor while other L-dNTPs and L-ATP showed 15-30% of the activity of the corresponding D-dNTP or D-ATP. L-dCTP inhibited dCK non-competitively with 2'-deoxycytidine (D-dCyd) and competitively with phosphate donor D-ATP.

Synthesis and evaluation of oligodeoxyribonucleotides containing an aryl(trifluoromethyl)diazirine moiety as the cross-linking probe: photoaffinity labeling of mammalian DNA polymerase beta.

Photolabile 2'-deoxy- E -5-[4-(3-trifluoromethyl-3 H-diazirin-3-yl)styryl]uridine and its protected phosphoramidite derivatives have been synthesized and introduced into DNA oligomers through solid-phase DNA synthesis. The (trifluoromethyldiazirinyl)stylyl moiety of this nucleoside was found to be sufficiently stable for automated DNA synthesis. In addition, this moiety was found to be stable at 60 degrees C in aqueous solution under the annealing conditions for duplex formation with complementary strands, since >95% of the photolabile nucleoside remained after heating for 1 h.

Chiral influences of feedback inhibition with dCTP on murine deoxycytidine kinase.

The inhibitory effects of 4 kinds of 2'-deoxy-L-nucleoside 5'-triphosphates, which are enantiomers of natural dNTPs, on murine deoxycytidine kinase (dCK) were investigated. When ATP was used as the phosphate donor, L-dCTP showed significant inhibitory action noncompetitively and competitively with 2'-deoxycytidine (dCyd) and ATP, respectively. Thus L-dCTP, like dCTP, could serve as a feedback inhibitor for dCK.

Effect of calcium ions on the irradiation induced inactivation of cellulase.

Abstract The activity of cellulase irradiated at various temperatures was examined as a function of irradiation dose. The effect of calcium ions in radiation inactivation of cellulase at irradiation temperature of 30°C was studied by using calcium sulfate. The calcium ions have a protective ability against radiation caused inactivation of cellulase by scavenging species such as OH(-) formed by irradiation of cellulase aqueous solution, in which the effective concentration range of the calcium ions was ∼ 10(-3) M.

A photolabile 2',3'-dideoxyuridylate analog bearing an aryl(trifluoromethyl)diazirine moiety: photoaffinity labeling of HIV-1 reverse transcriptase.

In order to develop a photoaffinity labeling reagent for DNA polymerases, including retroviral reverse transcriptase (RT), we utilized 2',3'-dideoxy-E-5-[4-(3-trifluoromethyl-3H-diazirin-3-yl) styryl]UTP (TDSddUTP) as a substrate dTTP analog. Photoaffinity labeling experiments with human immunodeficiency virus type-1 (HIV-1) RT using a radioactive labeling reagent ([gamma-32P]TDSddUTP) and poly(A).oligo(dT) as the template/primer yielded different results depending on the concentration of Mg2+.