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Although much is known today about the mode of action of antibiotics on microorganisms, relatively little has been done to evaluate the possible collaboration between antibiotics and the host defenses in the containment and elimination of pathogens from host tissues. Since certain antibiotics are known to interfere with the biosynthesis of bacterial cellular and extracellular components, it is conceivable that such modified bacterial cells may be more readily intercepted, killed, and eventually digested by professional phagocytes. On the other hand, certain antibiotics may have adverse effects on mammalian cells by interfering with their normal metabolism and subsequently with their antimicrobial functions. Although the role of bacteriolysis in host and parasite interrelationships has been recognized for over a decade, this field of research has surprisingly been almost totally neglected. The importance of understanding the mechanisms of biodegradation of microbial cells in vivo stems from the recognition that the inability of the enzymes of the host to degrade the rigid cell wall of microorganisms is a contributory factor to the formation of chronic granulomatous responses, and to the destruction of tissues [1, 6, 16, 17, 22, 30]. Thus, any antibiotics which will collaborate with leukocytes or with serum factors in the elimination of bacterial constitutents from infected tissues may greatly contribute to the well-being of the individual.

Effect of leukocyte hydrolases on bacteria XVI. Activation by leukocyte factors and cationic substances of autolytic enzymes in Staphylococcus aureus: modulation by anionic polyelectrolytes in relation to survival of bacteria in inflammatory exudates. The mechanisms involved in the activation of autolytic enzymes in Staphylococcus aureus, by leukocyte extracts, cationic proteins, phospholipase A2, amines, and membrane-damaging agents was studied in a resting cell system as well as by growing staphylococci. The bacteria were labeled with [14C]N-acetylglucosamine and were subjected to a variety of agents either in 0.1 M acetate buffer, pH 5.0, or in phosphate buffer, pH 7.4. While intact log-phase cultures were found to undergo partial autolysis at pH 5.0 and almost complete lysis at pH 7.4, both heat-killed bacteria and bacterial cell walls were completely resistant to autolysis in buffers. Autolysis at pH 5.0 can be further activated by leukocyte extracts, nuclear histone, crystalline ribonuclease, egg-white and human lysozyme, phospholipase A2, as well as by spermine, spermidine, and polymyxins B and E. The addition of viable log-phase bacteria to radiolabeled heat-killed staphylococci or to radiolabeled cell walls which had been cleaned off autolytic enzymes resulted in degradation of the radiolabeled targets. The data suggest that the various inducers of autolysin activation caused leakage of autolytic enzymes from the intact bacteria which attacked the depolymerized the bacterial cell walls. Anionic polyelectrolytes like heparin, dextran sulfate, suramine, polyglutamic acid, and liquid (polyanethole sulfonic acid) markedly inhibited both spontaneous and induced lysis. Staphylococci which had grown in the presence of anionic polyelectrolytes became highly resistant to lysis triggered by any of the inducers of autolysis. Since inflammatory exudates are known to be rich in anionic polyelectrolytes, it is suggested that the prolonged survival of intact bacterial cells in such a milieu may be due to the inactivation of autolytic enzymes. It is also postulated that the degradation of certain bacterial species following phagocytosis or extracellular degradation may not be the result of the action of hydrolytic enzymes but rather the result of activation by leukocyte factors of autolytic enzymes which lead to bacteriolysis.

Stearic acid can exit in 3 main crystal structure modifications. The crystal structure is detd. by solute-solvent interactions. When changes occur in the growth conditions, for instance in flow regime or by increased cooling rate, the crystal modification is affected. Addn. of small amts. of surfactants will force the stearic acid to crystallize in only one modification regardless of the crystn. and the nature of the solvent. [on SciFinder(R)]

Group A streptococci strains were grown in broth containing subminimal inhibitory concentrations of chloramphenicol, erythromycin and penicillin, and tested for possible changes in colonial morphology, activity and amount of cellular and extracellular components. The following components were tested: T protein, M protein, opacity factor, lipoteichoic acid, hyaluronic acid, streptolysin S, streptolysin O, DNase, hyaluronidase and NADase. Sub-MICs of these drugs produced variable changes in the bacteria. They increased the amount of hyaluronic acid and hyaluronidase, decreased the amount of M protein, and enhanced phagocytosis and the release of lipoteichoic acid. The results indicate that sub-MICs of chloramphenicol, erythromycin and penicillin may affect the pathogenicity and toxinogenicity of group A streptococci.

It is well known that the set of all zonoids (integrals of line segments) in R" (n>2) is a closed and nowhere defise subset in the space of all compact, convex and centrally symmetric subsets of R". We generalize this result to sets which are the integral of k-dimensional convex sets, k <n.

Southern blots of rat genomic DNA indicate the existence of at least 12 EcoRI DNA fragments containing actin gene sequences. By using specific probes and stringent conditions of hybridization, it was found that only one of these fragments contains sequences of the skeletal muscle alpha-actin gene. Recombinant bacteriophages originating from eight different actin genes were isolated from rat genomic DNA libraries. One of them, Act 15, contains the skeletal muscle actin gene. Another clone, Act I, contains a gene coding for a cytoplasmic actin, identified tentatively as the beta-actin gene. Both genes have a large intron very close to the 5’ end of their transcribed region, followed by several small introns. DNA sequence analysis and comparison with the available data on actin genes in other organisms indicated an interesting relationship between the positions of introns and the evolutionary relatedness. Several intron sites are conserved from at least the echinoderms to the vertebrates; others appear to be present in some actin genes and not in others.

It has been found that calcium oxalate stone formers have low UGOT and UGPT activity compared to healthy individuals. The urine of 23 stone formers and 19 controls has been tested for combined UGOT and UGPT activity. The effect of L-aspartic acid, alanine and L-glutamic acid on calcium oxalate precipitation has been tested. Only L-glutamic acid exerted a significant retardation effect at physiological concentrations. As GPT and GOT convert alanine and aspartic acid respectively into glutamic acid, a possible mechanism of retardation of kidney stone formation involving enzyme steps via glutamic acid creation in situ is suggested.[on SciFinder (R)]

Calcium ion concentration versus time was measured in solutions containing admixture of 10 per cent tested urine of normals and stone-formers, during induced calcium oxalate precipitation. A Discriminating Index was formulated by statistical analysis of the data. It was found that stone-formers and normals differ significantly with respect to the measurements and the Discriminating Indices. An equation to evaluate the odds of stone-forming based on results of an individual test has been derived. The Discrimination Index may be recommended as a diagnostic tool.[on SciFinder (R)]

Blast transformation of human peripheral blood lymphocytes by PHA is shown to be modulated by lipoteichoic acid (LTA) of Streptococcus mutans, by a cell-sensitizing factor of Actinomyces viscosus, as well as by a frozen and thawed extract of human leukocytes (LE). While small amounts of LE (5-50 micrograms/10(6) cells) significantly enhanced PHA-induced transformation, higher amounts showed a lesser effect on the blastogenic response. Both LTA and the A. viscosus extract did not cause any lymphocyte blastogenic effect when used alone. On the other hand LTA had an inhibitory effect and the A. viscosus extract had an enhancing effect when lymphocytes were pretreated by these agents and then exposed to PHA.