Development of physical forms of unintegrated retroviral DNA in mouse spinal cord tissue during ts1-induced spongiform encephalomyelopathy: elevated levels of a novel single-stranded form in paralyzed mice.

ts1 is a murine leukemia virus that causes rapidly evolving hindlimb paralysis in susceptible strains of mice. Following perinatal infection, three physical forms of unintegrated viral DNA were detected in the spinal cord by Southern blot hybridization. Linear and supercoiled closed-circle viral double-stranded DNAs were detected in both the central nervous system and non-central nervous system tissues. An elevated level of a novel minus-sense single-stranded form of viral DNA, which had a very high mobility in agarose gels, was correlated with the onset of symptoms of paralysis. As the severity of paralysis progressed, the level of this single-stranded form increased rapidly, with the highest level in the spinal cords of moribund mice. Since the virulence of a number of cytopathic retroviruses has been associated with the presence of increased amounts of unintegrated viral DNA in the tissues of the infected hosts, this novel form of highly mobile unintegrated single-stranded DNA may have a role in the neuropathogenesis of ts1.     

Lisofylline prevents leak, but not neutrophil accumulation, in lungs of rats given IL-1 intratracheally

Hybertson, Brooks M., Stuart L. Bursten, Jonathan A. Leff,Young M. Lee, Eric K. Jepson, Chris R. Dewitt, John Zagorski, Hyun G. Cho, and John E. Repine. Lisofylline prevents leak, but not neutrophil accumulation, in lungs of rats given IL-1intratracheally. J. Appl. Physiol.82(1): 226-232, 1997.Interleukin-1 (IL-1) is increased in lunglavages from patients with the acute respiratory distress syndrome, andadministering IL-1 intratracheally causes neutrophil accumulation and aneutrophil-dependent oxidative leak in lungs of rats. In the presentstudy, we found that rats pretreated intraperitoneally with lisofylline[(R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine (LSF)], an inhibitor of lysophosphatidic acid acyl transferase, which reduces the production of unsaturated phosphatidic acid species,did not develop the lung leak or the related ultrastructural abnormalities that occur after intratracheal administration of IL-1.However, rats pretreated with LSF and then given IL-1 intratracheally did develop the same elevations of lung lavage cytokine-induced neutrophil chemoattractant (CINC) levels and the same increased numbersof lung lavage neutrophils as rats given IL-1 intratracheally. Lungs ofrats given IL-1 intratracheally also had increased unsaturated phosphatidic acid and free acyl (linoleate, linolenate) concentrations compared with untreated rats, and these lipid responses were prevented by pretreatment with LSF. Our results reveal that LSF decreases lungleak and lung lipid alterations without decreasing neutrophil accumulation or lung lavage CINC increases in rats given IL-1 intratracheally.

     

Endogenous nitric oxide decreases xanthine oxidase-mediated neutrophil adherence: role of P-selectin

Terada, Lance S., John E. Repine, Dale Piermattei, andBrooks M. Hybertson. Endogenous nitric oxide decreases xanthine oxidase-mediated neutrophil adherence: role of P-selectin.J. Appl. Physiol. 82(3): 913-917, 1997.The oxygen radical-producing enzyme xanthine oxidase (XO) canpromote neutrophil adherence to endothelium. Recognizing that a balanceoften exists in inflammatory processes, we sought to determine whetherXO initiates antiadherent pathways. We found that bovine pulmonaryarterial endothelial cells (EC) exposed to XO released increasedamounts of nitrite into the media, reflecting an increased productionof nitric oxide (NO). When EC were subjected to shear stress, treatmentwith XO and/or the NO synthase inhibitorN-nitro-L-arginine(L-NNA) increased neutrophilrolling behavior and firm neutrophil adherence to EC in an additivefashion. Both rolling and adherent interactions were abolished bymonoclonal antibodies directed against P-selectin. In addition,treatment of EC with XO and/orL-NNA increased both surfaceexpression of P-selectin and release of von Willebrand factor intomedia. Finally, treatment of EC with the NO donor sodium nitroprussidedecreased XO-mediated neutrophil rolling and adherence. We concludethat XO stimulates EC to produce NO and that NO decreases theP-selectin-dependent neutrophil adhesion initiated by XO. Suchincreases in endogenous NO may constitute an importantnegative-feedback response to the acute proadhesive effects of XO.

     

The effect of the sugar source on citric acid production by Aspergillus niger

Summary Under otherwise identical fermentation conditions, the sugar source has been shown to have a marked effect on citric acid production by Aspergillus niger. Sucrose was the most favourable source, followed by glucose and fructose and then lactose. No citric acid was produced from galactose. Strong relationships were observed between citric acid production and the activities of certain enzymes in myccelial cell-free extracts prepared from fermentation samples. When sucrose, glucose, or fructose was the sugar source pyruvate carboxylase activity was high, but 2-oxoglutarate dehydrogenase activity was not detected. When galactose was the sugar source pyruvate carboxylase activity was low, but 2-oxoglutarate dehydrogenase activity was high. It is suggested that whereas glucose and fructose repress 2-oxoglutarate dehydrogenase, thereby causing accumulation of citric acid, galactose does not. The activity of aconitase showed a direct relationship to the citric acid production rate. Thus, the activity was highest when sucrose was the sugar source, and lowest when galactose was the source. It is suggested that when large amounts of citric acid are lost from the cell the activity of aconitase increases as a response to the diminished intracellular supply of its substrate.     

Carnitine, acetylcarnitine and the activity of carnitine acyltransferases in seminal plasma and spermatozoa of men, rams and rats.

The concentration of total carnitine (i.e. carnitine plus acetylcarnitine) was measured in seminal plasma and spermatozoa of men and rams. In ram semen, there was a close correlation between the concentration of spermatozoa and that of total carnitine in the seminal plasma, indicating that the epididymal secretion was the sole source of seminal carnitine. The percentage of total carnitine present as acetylcarnitine was 40% in seminal plasma and 70-80% in spermatozoa. The acetylation state of carnitine in seminal plasma was apparently not influenced by the metabolic activity of spermatozoa in ejaculated ram semen as no change was found in the plasma concentration of carnitine or acetylcarnitine up to 45 min after ejaculation. In spermatozoa, the activity of carnitine acetyltransferase (EC 2.3.1.7) was approximately equivalent to that of carnitine palmitoyltransferase (EC 2.3.1.21); and the activity of these enzymes was similar in ram and human spermatozoa but greater in rat spermatozoa. It is concluded that there is no correlation between the content of either total carnitine or the carnitine acyltransferases and the respiratory capacity of spermatozoa.