Induction of microbial variants of Pseudomonas pseudomallei in cultured rabbit alveolar macrophages.

Cultured alveolar and peritoneal macrophages obtained from normal and immunized rabbits were used to induce wall-defective microbial variants of Pseudomonas pseudomallei. Variants were iduced only by normal alveolar macrophages. The variants reverted to typical Pseudomonas forms either spontaneously or upon transfer into broth or agar.     

Inhibition of macromolecular synthesis by caffeine in Clostridium perfringens

Caffeine (2 mg/mL) inhibited the incorporation of [14C]adenine into actively growing cells of Clostridium perfringens NCTC 8679 in a dose-dependent manner. Also reduced by caffeine was incorporation of [14C]thymidine and 14C-labeled amino acids. No effect on guanine, uracil, adenosine, guanosine, or uridine was detected. Actual incorporation of [14C]caffeine or [14C]thymine in control cultures did not occur.     

Regulation of growth and macromolecular synthesis by putrescine and spermidine in Pseudomonas aeruginosa

Growth of P. aeruginosa, slowed by the addition of monofluoromethylornithine, difluoromethylarginine and dicyclohexylammonium sulfate, could be restored by addition of 0.1 mM putrescine plus 0.1 muM spermidine, or 0.1 mM spermidine or 5 mM putrescine by themselves. Lower concentrations of putrescine (0.1 mM - 1 mM) also partially reversed the growth inhibition. Conversion of putrescine to spermidine continued, although at a markedly reduced ratio, in the drug-inhibited cells, but intracellular spermidine concentrations remained depressed suggesting that reversal of inhibition by putrescine may be a direct effect. There was appreciable back-conversion of any added spermidine to putrescine with a demonstrable increase in total intracellular putrescine levels, making conclusions on the effects of spermidine ambiguous. Spermine (0.1 mM), a polyamine not present in bacteria, was also effective in reversing growth inhibition, probably because of its conversion into spermidine and putrescine. The effects of putrescine, spermidine and spermine were specific in that the non-physiological amines, 1,3-diaminopropane, 1,5-diaminopentane (cadaverine), 1,6-diaminohexane, or 1,7-diaminoheptane could not reverse the effects of the three drugs. Rates of total protein, RNA and DNA synthesis were all slowed to the same extent as growth rate and showed similar recovery with the addition of putrescine or spermidine. A role for putrescine in P. aeruginosa growth processes is suggested.     

Phagocytability of Pseudomonas pseudomallei

Experiments were conducted on the cell culture of macrophages of animals significantly differing by the extent of resistance to melioidosis; the presence of correlation between the extent of the animal natural immunity and the intensity of dying of the microbes in the test system was demonstrated. The causative agent of melioidosis proved to be more resistant to phagocytosis with guinea pig macrophages than E. coli. Ps. aeruginosa and A. mallei. It was impossible to establish any relationship between the efficacy of phagocytosis by animal macrophages and the virulence or morphology of the colonies in the Ps. pseudomallei species.     

Inhibition of hyaluronan synthesis by vesnarinone in cultured human myofibroblasts

Hyaluronan (HA), which is a major component of the extracellular matrix (ECM), is regulated during myofibroproliferative responses to numerous forms of inflammatory stimuli. It is a key factor involved in cellular migration and adherence. The development of a potent and non-toxic inhibitor of HA synthesis would open up a new avenue for the treatment of fibrocontractive diseases such as pulmonary fibrosis and liver cirrhosis. In this study, the effects of vesnarinone (OPC-8212: 3,4-dihydro-6-[4-(3, 4-dimethoxybenzoyl)-1-piperazinyl]-2(1H)-quinolinone) on the secretion of HA in human myofibroblast cell lines (MRC-5 and LI90 cells, referred to as pulmonary and hepatic myofibroblasts, respectively) were examined. Vesnarinone specifically and dose-dependently inhibited HA secretion by myofibroblasts up-regulated by fetal calf serum (FCS). The treatment of vesnarinone did not modify the phenotype of myofibroblast cells in culture. Vesnarinone also potently inhibited the HA secretion by the two myofibroblast cell lines up-regulated by transforming growth factor-beta1 (TGF-beta1) or tumor necrosis factor-alpha (TNF-alpha). The addition of vesnarinone to myofibroblasts resulted in a significant decrease of HA synthase (HAS) activity, with or without the addition of FCS or either cytokine. These findings suggest that vesnarinone inhibits the secretion of HA in myofibroblasts by specifically suppressing HAS activity, and may therefore prove useful for the treatment of chronic inflammation and tissue fibrosis.     

Inhibition of synthesis of alpha-fetoprotein by glucocorticoids in cultured hepatoma cells

alpha-Fetoprotein (AFP) synthesis was studied in the presence and absence of glucocorticoids in rat hepatoma Mc-A-RH-7777 cells. Radioimmunoassay of media from cell cultures grown in the presence of glucocorticoid (dexamethasone or cortisol) showed a reduction in AFP, an increase in albumin, and no significant change in transferrin accumulation, as compared to controls. Labeling experiments with L-[35S]methionine indicated that in both cells and media of dexamethasone-treated cultures there was a 50--80% reduction in polypeptide precipitated by anti-AFP serum, as compared with controls; no change was seen in polypeptide precipitated by anti-transferrin serum. Pulse and pulse-chase experiments demonstrated that dexamethasone inhibited the synthesis of AFP but not its secretion. The half-time for secretion of AFP in the presence and absence of dexamethasone was 43 min.     

假单孢菌外毒素A的介绍

介绍了假单孢菌外毒素Ａ的理化性质,分子结构与功能的关系以及假单孢菌外毒素Ａ的应用前景。     

Rapid differentiation of Pseudomonas pseudomallei from Pseudomonas cepacia

The Minitek disc system was utilized for the differentiation of Pseudomonas pseudomallei, the causative agent of melioidosis, from Ps. cepacia. The system was simple to use, inexpensive, and furnished rapid, clear-cut test results after 4 h. This procedure is suitable for differentiating soil bacteria presumptively identified as Ps. pseudomallei, Ps. cepacia or flavobacteria, and for the rapid confirmation of the presumptive identification of either Ps. pseudomallei or Ps. cepacia obtained by commercial identification-kit systems in the clinical laboratory.     

Spontaneous genetic transformation in Pseudomonas pseudomallei

Spontaneous genetic transformation has been registered in Pseudomonas pseudomallei cells. Transforming frequencies registered reach 10(-4)-10(-5). Spontaneous transformation has been simulated for Pseudomonas pseudomallei in soil. Intrageneric spontaneous transformation has been demonstrated to occur between Pseudomonas pseudomallei and Pseudomonas mallei.     

Prevalence of antibodies to Pseudomonas pseudomallei exotoxin and whole cell antigens in military personnel in Sabah and Sarawak, Malaysia.

Sera from 420 military personnel serving in Sabah and Sarawk, Malaysia, were tested for antibodies to Pseudomonas pseudomallei exotoxin and whole cell antigens by enzyme-linked immunosorbent assay procedure (ELISA). Data showed that 54.4% of serum samples were positive for antibodies to P. pseudomallei exotoxin and 65.7% were positive for antibodies to the whole cell antigens. Samples gave much lower titers for anti-exotoxin antibodies compared to titers against crude whole cell antigens. The incidence of antibody to exotoxin was highest in the age groups ranging from 26 to 32 years, where the positive rates were higher than 40% and 30% for military personnel serving in Sarawak and Sabah, respectively.     

Inhibition of macromolecular synthesis in tumors by L-1-tosylamido-2-phenylethyl chloromethyl ketone.

L-1-tosylamido-2-phenylethyl chloromethyl ketone was observed to inhibit the incorporation of [³H] amino acids into protein and [³H] thymidine incorporation into DNA in Novikoff hepatoma ascites cells $\text{in vitro}$ Similar effects were seen with several Morris hepatomas and a transplanted colon tumor in rats, and were accompanied by decreased uptake of isotope into acid soluble tissue fractions. Under the same conditions, there was no significant inhibition in regenerating liver and there was an increased uptake of [³H] amino acids in the livers of normal and tumor bearing rats.     

Inhibition of proteoglycan synthesis by hydrogen peroxide in cultured bovine articular cartilage

Oxygen-derived reactive species, generated enzymatically by the action of xanthine oxidase upon hypoxanthine, significantly inhibit proteoglycan synthesis by cultured bovine articular cartilage (Bates, E.J., Lowther, D.A. and Handley, C.J. (1984) Ann. Rheum. Dis. 43, 462-469). Here we extend these investigations and show, through the use of catalase and the specific iron chelator diethylenetriaminepentaacetic acid, that the active species involved is H2O2 and not the hydroxyl radical. Incubations of cartilage with H2O2 at concentrations of 1 X 10(-4) M and above are also inhibitory to proteoglycan synthesis. Subsequent recovery of the tissue is dependent upon the initial dose of xanthine oxidase or H2O2. Xanthine oxidase at 84 mU per incubation results in a prolonged inhibition of proteoglycan synthesis which is still apparent after 14 days in culture. Lower concentrations of xanthine oxidase (21-66 mU) are inhibitory to proteoglycan synthesis, but the tissue is able to synthesise proteoglycans at near normal rates after 3 days in culture. The inhibition of proteoglycan synthesis by 1 X 10(-4) M H2O2 is completely reversed after 5 days in culture, whereas 1 X 10(-3) M H2O2 results in a more prolonged inhibition. The synthesis of the proteoglycan core protein is inhibited, but the ability of the newly formed proteoglycans to aggregate with hyaluronic acid is unimpaired.