Degradation of long chain alkanes by bacilli

Summary Among 14 different types of bacillus and 100 isolates from soil samples, no bacillus was able to assimilate C₁₄-C₁₈ alkanes as sole carbon source. In contrast to these results, five types of bacillus were substantially able to oxidize alkanes in the presence of other carbon sources.All five strains tested formed relatively high amounts of secondary alcohol in contrast to low amounts of ketones and traces of primary alcohols with chain length equivalent to the n-alkane in the substrate, showing that the degradation pathway in bacilli is mainly subterminal.This conclusion is also supported by comparison of the extracellular fatty acids of cultures of bacilli grown on n-tridecane and on n-tetradecane supplemented with other carbon sources and on the same carbon sources without alkane.     

Complement C1q and C3 are critical for the innate immune response to Streptococcus pneumoniae in the central nervous system

Previous studies suggest that the complement system can contribute to limiting pneumococcal outgrowth within the CNS. In this study, we evaluated the role of the complement system in the activation of the innate immune response and the development of the prognosis-relevant intracranial complications in a murine model of pneumococcal meningitis. Thereby, we used mice deficient in C1q, lacking only the classical pathway, and C3, lacking all three complement activation pathways. At 24 h after intracisternal infection, bacterial titers in the CNS were almost 12- and 20-fold higher in C1q- and C3-deficient-mice, respectively, than in wild-type mice. Mean CSF leukocyte counts were reduced by 47 and 73% in C1q- and C3-deficient-mice, respectively. Intrathecal reconstitution with wild-type serum in C3-deficient mice restored both the ability of mice to combat pneumococcal infection of the CSF and the ability of leukocytes to egress into the CSF. The altered recruitment of leukocytes into the CSF of C3-deficient mice was paralleled by a strong reduction of the brain expression of cytokines and chemokines. The dampened immune response in C3-deficient mice was accompanied by a reduction of meningitis-induced intracranial complications, but, surprisingly, also with a worsening of short-term outcome. The latter seems to be due to more severe bacteremia (12- and 120-fold higher in C1q- and C3-deficient-mice, respectively) and, consecutively, more severe systemic complications. Thus, our study demonstrated for the first time that the complement system plays an integral role in mounting the intense host immune response to Streptococcus pneumoniae infection of the CNS.     

Estrous cycle-dependent histology and review of sex steroid receptor expression in dog reproductive tissues and mammary gland and associated hormone levels

This report describes normal histology of tissues from immature female dogs and sequential microscopic changes that occur during different stages of the estrous cycle in ovary, uterus, vagina and mammary glands. These observations are associated with a literature review of concurrent estrous cycle plasma hormone levels and expression of sex steroid receptors in these tissues. The combined review of different aspects of the estrous cycle in the dog provides readers with a comprehensive presentation and may guide investigators that are involved in testing compounds with hormonal effects in female dogs.     

Long-lasting plasma membrane permeabilization in mammalian cells by nanosecond pulsed electric field (nsPEF)

The barrier function of plasma membrane in nsPEF-exposed mammalian cells was examined using whole-cell patch-clamp techniques. A specialized setup for nsPEF exposure of individual cells in culture was developed and characterized for artifact-free compatibility with the patch-clamp method. For the first time, our study provides experimental evidence that even a single 60-ns pulse at 12 kV/cm can cause a profound and long-lasting (minutes) reduction of the cell membrane resistance (R(m)), accompanied by the loss of the membrane potential. R(m) measured in GH3, PC-12, and Jurkat cells (but not in HeLa cells) in 80-120 s after nsPEF exposure was decreased about threefold, and its gradual recovery could take 15 min. Multiple pulses enhanced permeabilization, for example, R(m) in GH3 cells fell about 10-fold after a train of five pulses. Within studied limits, permeabilization did not depend on the presence of Ca(2+), Mg(2+), K(+), Cs(+), Cd(2+), EGTA, tetraethylammonium, or 4-aminopyridine in the pipette or bath solutions. Our results supported theoretical model predictions of plasma membrane poration by nsPEF. However, the extended decrease in R(m), assumed to be related to the life span of the pores, and different nsPEF sensitivity of individual cell lines have yet to be explained. The phenomenon of long-lived membrane permeabilization provides new insights on the nature of nsPEF-opened conductance pores and on molecular mechanisms that underlie nsPEF bioeffects.     

Influence of chloride on modification of unsaturated phosphatidylcholines by the myeloperoxidase/hydrogen peroxide/bromide system

The leukocyte enzyme myeloperoxidase (MPO) is capable of catalyzing the oxidation of chloride and bromide ions, at physiological concentrations of these substrates, by hydrogen peroxide, generating hypochlorous acid (HOCl) and hypobromous acid (HOBr), respectively. Our previous results showed that the hypohalous acids formed react with double bonds in phosphatidylcholines (PCs) to produce chloro- and bromohydrins. Lysophosphatidylcholine (lyso-PC) is additionally formed in PCs with two or more double bonds. This study was conducted to determine the effect physiological chloride concentration (140 mM) has on the formation of bromohydrins and lyso-PC from unsaturated PC upon treatment with the myeloperoxidase/hydrogen peroxide/bromide (MPO/H2O2/Br-) system using physiological bromide concentrations (20-100 microM). The composition of reaction products was analyzed by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS). With monounsaturated PC, we demonstrated that the rate and extent of mono-bromohydrin formation were higher in the samples with 140 mM chloride compared to those with no added chloride. Moreover, mono-bromohydrin came to be the major product and no mono-chlorohydrin was observed already at 60 microM bromide. We attributed these effects to the involvement of HOBr arising from the reaction of MPO-derived HOCl with bromide rather than to the exchange of bromide with chlorine atoms of chlorohydrins or direct formation of HOBr by MPO. The presence of chloride shifted the pH optimum for mono-bromohydrin formation (pH 5.0) toward neutral values, and a significant yield of mono-bromohydrin was detected at physiological pH values (7.0-7.4). For polyunsaturated PC, chloride enhanced also lyso-PC production, the effect being pronounced at bromide concentrations below 40 microM. The results indicate that at physiological levels of chloride and bromide, chloride promotes MPO-mediated formation of bromohydrins and lyso-PC in unsaturated phospholipids.