An approach to branched-chain amino sugars, particularly derivatives of -vancosamine (3-amino-2,3,6-trideoxy-3-C-methyl- -lyxo-hexose) and its enantiomer, via the cyanohydrin route

Methyl 4,6-O-benzylidene-2-deoxy-α- -erythro-hexopyranosid-3-ulose reacted with potassium cyanide under equilibrating conditions to give, initially, methyl 4,6-O-benzylidene-3-C-cyano-2-deoxy-α- -ribo-hexopyranoside (7), which, because it reverted slowly to the thermodynamically stable -arabino isomer, could be crystallised directly from the reaction mixture. The mesylate derived from the kinetic product 7 could be converted by published procedures into methyl 3-acetamido-2,3,6-trideoxy-3-C-methyl-α- -arabino-hexopyranoside, which was transformed into methyl N-acetyl-α- -vancosaminide on inversion of the configuration at C-4. A related approach employing methyl 2,6-dideoxy-4-O-methoxymethyl-α- -erythro-hexopyranosid-3-ulose gave the kinetic cyanohydrin and thence, via the spiro-aziridine 27, methyl 3-acetamido-2,3,6-trideoxy-3-C-methyl-α- -arabino-hexopyranoside, a known precursor of methyl N-acetyl-α- -vancosaminide.     

Kinetics of Mg2+-dependent CF1-ATPase in the presence of stimulators

A kinetic study of ATP hydrolysis by CF1-ATPase from chloroplasts in the presence of optimal concentrations of the stimulators, sodium sulfite and ethyl alcohol, has been carried out. At MgCl2/ATP ratios more than 1 the reaction kinetics obey the Michaelis--Menten equation. At ATP excess the kinetics are of the second order with respect to Mg2+. The data obtained are consistent with the hypothesis on the formation of an enzyme substrate Mg.CF1-MgATP complex containing beside Mg-ATP substrate Mg2+. The dependence of the maximal rate of the reaction on pH was studied. Two active groups with pK of 6.3 and 8.9 were revealed. The group responsible for Mg+2 binding to the enzyme has a pK of 8.3. The possible nature of the active groups of the enzyme is discussed.     

An investigation of the molecular properties and stability of intermediates of proenkephalin in isolated bovine adrenal medullary chromaffin granules

An antiserum to a synthetic peptide corresponding to residues 95-117 of bovine proenkephalin recognizes all the major intermediates of this prohormone in bovine adrenal medulla (Birch, N. P. and Christie, D. L. (1986) J. Biol. Chem. 261, 12213-12221). This antiserum enabled an investigation of the stability and molecular properties of intermediates in the processing of proenkephalin in bovine adrenal medullary chromaffin granules. Intact and hypotonic lysates of chromaffin granules were incubated at 37 degrees C and the stability of intermediates assessed by gel filtration followed by radioimmunoassay and gel electrophoresis in combination with immunoblotting. Processing was slow in intact granules compared with incubations of hypotonic lysates which resulted in the selective cleavage of an Mr 27,000 intermediate and increases in the amounts of immunoreactivity of lower molecular weight. Protease inhibitors increased the stability of the 27-kilodalton intermediate, the most effective being p-chloromercuribenzoate. Preliminary evidence was obtained for the regulation of the processing of this intermediate by soluble factors present in chromaffin granules. It appears that membrane-associated intermediates of proenkephalin are relatively stable, although analysis of soluble immunoreactivity released during the incubation of chromaffin granule membranes showed a decrease in the 27-kilodalton intermediate and increased amounts of lower molecular weight intermediates. Analysis of hypotonic lysates by two-dimensional gel-electrophoresis showed that proenkephalin intermediates exhibit significant microheterogeneity. It will be important to compare the products of proenkephalin generated by purified proteases with a putative role in the processing of this prohormone with the properties of endogenous intermediates as revealed in this study.     

Human globin gene expression after gene transfer

Human globin genes can be transferred into mouse and human erythroid cells in culture, and can be appropriately expressed at the mRNA level in these cells. A plasmid containing a human beta globin gene is expressed in mouse erythroleukemia cells (MELC), and another containing a human epsilon or gamma gene is expressed in human erythroleukemia (K562) cells. A neomycin resistance (neoR) gene on the plasmids has been used to select for those cells containing the transferred globin genes; this selection may favor the expression of the globin genes by providing chromosomal positions requiring neoR expression. Analyzing clones resistant to G418, a neomycin analogue, demonstrated globin mRNA expression and induction. Retroviral vectors have also been used to transfer and appropriately express human beta genes in MELC. In addition, a plasmid containing a dihydrofolate reductase (DHFR) gene as well as neoR and beta globin genes has been used to amplify and express beta globin mRNA in MELC. These experiments suggest that high level appropriate expression of human beta globin genes is feasible and provides potentially useful approaches to the long-range goal of gene therapy for sickle cell anemia and beta thalassemia.     

Effect of adenine nucleotides on the activator function of streptokinase

The addition of ATP or 3,5-AMP (but not UTP, GTP, CTP, AMP, 2,3-AMP, ADP, inorganic pyrophosphate) at a final concentration of 10(-1) M into streptokinase solution, pH 7.0 or 9.5, causes a dramatic inhibition of streptokinase-induced fibrinolysis. The specificity of ATP effect is fully lost at pH 3.0, when all nucleotides completely inhibit the activating function of streptokinase. Ribose-5-phosphate causes a similar effect at pH 3.0. The character of nucleotide action on the activating function of streptokinase considerably differs from their influence on proteolytic reactions.     

Effect of the spinal pain syndrome on pain reactions caused by nociceptive thermal stimuli

It has been shown that the reaction of both limbs to thermal pain stimulation was suppressed during spinal pain syndrome development caused by generators of pathologically enhanced excitation (GPEE) formed in the dorsal horns of the spinal cord lumbosacral segments on one side. The analgetic effect on physiological pain was retained long after pain syndrome disappearance (48 hours), the effect was bilateral and was independent of the type of agent producing GPEE. It was shown that neuronal activity in the antinociceptive system key structure (nucleus raphe dorsal) increases. It is assumed that physiological pain relief is caused by enhanced activity in antinociceptive system structures in pain syndrome.     

Decrease in the degree of lipoid infiltration of rabbit tissues during feeding with cholesterol freed from autoxidation products

Lipid accumulation in the rabbit liver and myocardium has been investigated by histochemical and biochemical methods. The rabbits received cholesterol that contained 5% of autooxidation products or purified cholesterol. Lipid accumulation took place in the liver and intramural myocardial vessels during feeding of rabbits with autooxidated cholesterol. Feeding with pure cholesterol free from autooxidation products caused but slight changes or no changes at all.     

Quantitative characteristics of nitroblue tetrazolium reduction by the neutrophils in experimental systemic candidiasis

The quantitative study of the reduction capacity of neutrophils with respect to nitro blue tetrazolium in experimental systemic candidiasis has revealed an increase in this capacity within 20 days of the infection. The reduction capacity has been found to depend not only on the degree of the contamination of the body with Candida cells, but also on the stage of the inflammatory process.     

The Effects of Misspecification of a Regression Model

The consequences of the misspecification of a regression model are considered. For small effects of covariates a proportional consistency theorem is derived. The consistent estimation of the covariance matrix of the estimates is discussed.     

Distribution of epitheliocytes by the number of Candida albicans adhered to them and assessment of the intensity of the adhesion in an in vitro test

The study of the adhesion test in suspensions, carried out with 9 C. albicans strains and human buccal epithelial cells, has revealed that these cells are exponentially distributed by the number of C. albicans cells adhered to them. To characterize adhesion, the use of the index of the exponent describing the distribution of epithelial cells is proposed. With the use of this index, 5 C. albicans strains isolated from candidiasis patients have been found to possess, on the average, higher adhesiveness with respect to epithelial cells than 4 strains isolated from persons without symptoms of candidiasis.