The respiratory burst activity of neutrophil leukocytes from bovine peripheral blood was studied before and during an experimentally induced Escherichia coli mastitis. The competence of neutrophils to generate reactive oxygen species following stimulation with opsonized particles prior to infection was negatively correlated with severity of subsequently induced E. coli mastitis. In the presence of the soluble activator, phorbol myristate acetate, no such correlation was obtained. However, combination of blood neutrophil numbers with phorbol myristate acetate induced respiratory burst competence, called reactive oxygen speciesgenerating capacity, displayed a negative correlation with the intensity of a subsequent inflammation of the bovine mammary gland.At the onset of mastitis, a concomitant reduction in blood neutrophil numbers, a strong shift in cell types, and a substantial decrease in production of reactive oxygen species occurred. Reestablishment and even enhancement of the respiratory burst activity coincided with the reappearance of mature neutrophils. Possible stimulatory effects on neutrophil superoxide generation are discussed. Data suggest that generation of reactive oxygen species by mature neutrophils may be of primary importance for microbial killing during the onset and recovery from mastitis.

A postnuclear cell fraction from resting horse polymorphonuclear (PMN) leukocytes incubated with fatty acid-salt ions such as oleate or linoleate generated a NADPH-dependent oxygen consumption and superoxide production. Oxidative activity was negligible or absent in the postnuclear fraction from mononuclear leukocytes, p-chloromercuribenzene sulfonic acid-treated granulocytes, and granulocytes from a patient with chronic granulomatous disease. Although consistently associated with the membrane fraction from resting PMN leukocytes, the superoxide-generating activity was shown to be dependent on a thus far unknown cytosolic constituent. The apparent Km's for NADPH and NADH (66 and 1,600 microM, respectively), the pH optimum for the reaction (7.0), the cyanide insensitivity, and transient nature of the reaction together with the stoichiometric relationship between oxygen uptake and NADPH oxidation led to the conclusion that in the presence of cytosol a cell-free latent respiratory burst oxidase can be converted into an active enzyme by interaction with oleate micelles.

Dextran was modified using three different methods: a) partial periodate oxidation and subsequent reduction of the aldehyde groups, b) suc cinoylation and c) chloroformate activation with subsequent reaction with 2- hydroxypropylamine, ethylenediamine and tris(2-aminoethyl)amine. Degrada tion of these dextran derivatives by dextranases was investigated. It was observed that the rate of degradation decreased with increasing degree of chemical modification of the parent polysaccharide. The nature of modification had no significant influence on the rate of degradation.

Dextran was activated by reaction with 4-nitrophenyl chloroformate. Analysis of the total carbonate content and the content of 4-nitrophenyl carbonate moieties during the course of the reaction demonstrate the formation of different types of carbonate moieties. The 4-nitrophenyl carbonate moieties are transformed into other carbonate structures most likely by reaction with neighbouring polymeric hydroxyls. This process is strongly enhanced by addition of a strong base.