Restoration of hepatic cytochrome c oxidase activity and expression with acetyl-L-carnitine treatment in spf mice with an ornithine transcarbamylase deficiency

The sparse fur (spf) mutant mouse, with an X-linked ornithine transcarbamylase deficiency, is a model of congenital hyperammonemia in children. Our earlier studies indicated a deficiency of hepatic carnitine, CoA-SH, acetyl CoA, and ATP in spf mice. We have now studied the effects of a 7-day treatment with acetyl-L-carnitine (ALCAR) in the spf/Y mice on the activity and expression of the respiratory chain enzyme cytochrome c oxidase (COX; EC 1.9.3.1). We found decreased hepatic activity and expression of COX in the untreated hyperammonemic spf/Y mice, which was restored upon ALCAR treatment. Because COX is a mitochondrial membrane protein, we also carried out studies to explain the mechanism of ALCAR through its effect on membrane stability. Our results indicate a decrease of the mitochondrial membrane cholesterol/phospholipid molar ratio (CHOL/PL ratio) with the activity and expression of COX in untreated spf/Y mice. While ALCAR treatment normalized the ratios, it also restored the hepatic ATP production to normal. To study further if there was any effect of ALCAR on the mitochondrial matrix urea cycle enzymes, we measured the activity and expression of mutant ornithine transcarbamylase (OTC; EC 2.1.3.3) and normal carbamyl phosphate synthase-I (CPS-I; EC 6.3.4.16) in spf/Y mice. There was no general effect on the specific activities of the matrix enzymes upon ALCAR treatment, although their mRNA levels were enhanced. Our studies point towards the feasibility of an ALCAR treatment in conjunction with other treatment modalities, e.g. sodium benzoate and/or arginine, to improve the availability of cellular ATP and to counteract the effects of hereditary hyperammonemic syndromes in children.     

Generation of sanazole nitro radicals by xanthine oxidase

The formation of sanazole (drug AK-2123) radicals by the xanthine--xanthine oxidase system was studied by spectrophotometry in hypoxygenic (pO2 = 45 +/- 5 mm Hg) and normoxygenic (pO2 = 150 +/- 4 mm Hg) media. At concentrations from 0.1 to 10.5 mM, sanazole dose-dependently increased the rate of cytochrome c reduction in hypoxygenic medium but had no effect on the reaction rate under normoxygenic conditions. The activating influence of sanazole depended on xanthine concentration. At xanthine concentrations from 0.08 to 0.1 mM in hypoxygenic medium, the rate of cytochrome c reduction was increased twofold after the addition of sanazole. Reduction of cytochrome c in the medium without sanazole was completely blocked by superoxide dismutase; addition of sanazole partially restored the blocked reaction. Cytochrome c reduced in the presence of superoxide dismutase and sanazole was oxidized by cytochrome oxidase. The data indicate that in the presence of the xanthine--xanthine oxidase system under hypoxygenic conditions, sanazole can accept electrons and generate nitro radicals which donate electrons to cytochrome c or oxygen.     

Structure determination for octasaccharides derived from the carbohydrate-protein linkage region of chondroitin sulphate chains in the proteoglycan aggrecan from bovine articular cartilage

Five octasaccharides derived from the protein carbohydrate linkage region of chondroitin sulphate (CS) have been isolated from the large aggregating proteoglycan (aggrecan) extracted from the bovine articular cartilage of 6-year-old to 8-year-old animals. Following the purification of aggrecan the attached CS chains were digested with CS ABC endolyase and subsequently released from the protein core by beta-elimination. The individual oligosaccharides were purified by strong anion-exchange chromatography and their structures determined by very high-field one-dimensional and two-dimensional 1H-NMR spectroscopy. They were found to be octasaccharides, comprised of tetrasaccharide repeat-region extensions to the core tetrasaccharide linkage region structure. They have the following structures: deltaUA(beta1-3)GalNAc(beta1-4)GlcA(beta1-3)GalNAc(beta1-4)+ ++GlcA(beta1-3)Gal(beta1-3)Gal(beta1-4)Xyl-ol, deltaUA(beta1-3)GalNAc(beta1-4)GlcA(beta1-3)GalNAc6S(b eta1-4)GlcA(beta1-3)Gal(beta1-3)Gal(beta1-4)Xyl-ol, deltaUA(beta1-3)GalNAc6S(beta1-4)GlcA(beta1-3)GalNAc(b eta1-4)GlcA(beta1-3)Gal(beta1-3)Gal(beta1-4)Xyl-ol, deltaUA(beta1-3)GalNAc6S(beta1-4)GlcA(beta1-3)GalNA c6S(beta1-4)GlcA(beta1-3)Gal(beta1-3)Gal(beta1-4)Xyl-ol and deltaUA(beta1-3)GalNAc4S(beta1-4)GlcA(beta1-3)GalNA c6S(beta1-4)GlcA(beta1-3)Gal(beta1-3)Gal(beta1-4)Xyl-ol. They differ only in the nature of the sulphation of the GalNAc residues of the tetrasaccharide-repeat-region extension, which forms the first two disaccharides of the repeat region. No sulphation of any of the uronic acid residues has been identified and in one oligosaccharide neither of the GalNAc residues were sulphated. The majority of the linkage regions contained GalNAc residues which were fully 6-sulphated. However, in a significant amount, only one of the residues was 6-sulphated while the other was either unsulphated or 4-sulphated. There was no evidence either for sulphation of the linkage region galactose residues or for phosphorylation of the xylose residue, through which the chain is attached to the core protein.     

Computational neural networks for predictive microbiology: I. Methodology

Artificial neural networks are mathematical tools inspired by what is known about the physical structure and mechanism of the biological cognition and learning. Neural networks have attracted considerable attention due to their efficacy to model wide spectrum of challenging problems. In this paper, we present one of the most popular networks, the backpropagation, and discuss its learning algorithm and analyze several issues necessary for designating optimal networks that can generalize after being trained on examples. As an application in the area of predictive microbiology, modeling of microorganism growth by neural networks will be presented in a second paper of this series.     

Human IgG Fc receptors

Human IgG receptors constitute a family of glycoprotein complexes consisting of ligand-binding, and associated signaling chains. Three leukocyte classes (Fc gamma RI, II, and III) and one separate endothelial Fc gamma R class (FcRB) are defined which are expressed on hematopoietic and endothelial cells. Upon interaction with IgG, Fc gamma R initiate a plethora of signaling cascades involving receptor signaling motifs, and protein tyrosine kinases and phosphatases. These cascades ultimately culminate in activation or deactivation of effector cells, resulting in initiation or down-modulation of cellular processes. Recent evidence points to a crucial in vivo role of Fc gamma R in both initiation and regulation of inflammatory and cytotoxic responses. These Fc gamma R-mediated immune responses can be exploited to develop novel immunotherapies.     

Oligonucleotide dendrimers: synthesis and use as polylabelled DNA probes

Oligonucleotide dendrimers were synthesized using a novel phosphoramidite synthon, tris-2,2,2-[3-(4,4'-dimethoxytrityloxy) propyloxymethyl]ethyl- N , N -diisopropylaminocyanethoxy phosphoramidite. Label, incorporated using [gamma-32P]ATP and polynucleotide kinase, was increased in proportion to the number of 5'-ends. There was a similar increase in signal when these multiply labelled oligonucleotides were used as probes to oligonucleotide arrays. A dendrimeric oligonucleotide was used successfully as a primer in the PCR. The strand bearing the dendrimer was resistant to degradation by T7 Gene 6 exonuclease making it easy to convert the double-stranded product of the PCR to a multiply-labelled, single-stranded probe.     

The characteristics of the clinical course in individual types of radiation-induced cataracts

Twenty-eight patients exposed to acute and chronic ionizing radiation were followed up. Radiation cataracts were diagnosed in 22 eyes. Localizations of changes in the lens after ionizing and solar radiation are similar. Opacities are localized under the posterior lenticular capsule, round the nucleus, and under the anterior capsule and do not depend on the type of radiation. Opacities caused by solar radiation are notably smaller and look as numerous small dots. Study of cataracts of different origin and assessment of the efficacies of different anticataract drugs were carried out for evaluating the progress of different types of cataracts (cellular, extracellular, and capsular forms).