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Query: UNIPROT:P30536 (PBS)
 9,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to investigate whether defective phages of Bacillus subtilis killed sensitive bacteria by a lysis from without mechanism, the minimal number of phages required for killing was determined. This figure was found to vary with the m.o.i., giving a value of 1 on extrapolation to an m.o.i. of 0. This excluded lysis from without as the only killing mechanism, although it might play a role at high m.o.i.s. This was confirmed by experiments on leakage of ATP and u.v.-absorbing material, the uptake of oxygen and the effect of the phages on the membrane potential. Apart from a short, initial leakage of ATP, the cell membrane was not affected at low m.o.i.s. These results lead to the conclusion that at low m.o.i.s. the phages acted on a cytoplasmic component. Treatment of defective phages for 10 min at pH 2.5 resulted in breakdown of the phages without complete abolition of the killing activity. The active component, which was shown not to be DNA, could not be isolated from the mixture, but SDS gel electrophoresis of PBS X and a non-killing mutant of this phage suggested that a protein with a mol. wt. of 85000 was involved in killing.
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PMID:Effect of defective phages on the cell membrane of Bacillus subtilis and partial characterization of the phage protein involved in killing. 679 49

Serpulina hyodysenteriae produces an oxygen-stable heat-labile hemolysin that may be an important virulence factor in the pathogenesis of swine dysentery. We examined the effect of Ca2+, Co2+, Cu2+, Fe2+, Mg2+, Mn2+, Ni2+, and Zn2+ on the hemolytic activity of cell-free supernatant (CFS) from S. hyodysenteriae, isolate B204. Cells harvested from late logarithmic phase cultures were incubated in phosphate-buffered saline containing glucose and RNA-core (PBS-GR) with or without cations and the hemolytic activity of CFS obtained after successive 30 min incubation and washing cycles was determined. The addition of either ZnSO4 or CuSO4 to the PBS-GR caused complete inhibition of hemolytic activity after 3 cycles; other cations gave results similar to control extracts. Reduction in the concentration of Zn2+ in CFS by 60 to 80% after each incubation cycle and binding of Zn2+ by EDTA indicated that Zn2+ was associated with the cell fraction, and inhibition of hemolysin activity was specifically mediated by Zn2+. When the spirochetes were washed after incubation in the presence of ZnSO4 for 2 cycles and incubated in fresh PBS-GR without Zn2+, inhibition of hemolysin activity remained unchanged, indicating that the inhibitory effect of ZnSO4 was due to a direct action of ZnSO4 on the spirochetes. Since neither the viability of the spirochetes nor the activity of pre-formed hemolysin were affected by the presence of ZnSO4, the inhibitory effect of Zn2+ cations was attributed to reduced biosynthesis by viable S. hyodysenteriae cells rather than interference of Zn2+ cations with lysis of erythrocytes by the hemolysin. Transmission electron microscopic examination of spirochetes after incubation in PBS-GR containing ZnSO4 revealed clumping of ribosomes and clearing of cell cytoplasm.
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PMID:Effect of divalent cations on hemolysin synthesis by Serpulina (Treponema) hyodysenteriae: inhibition induced by zinc and copper. 780 26

A dose-dependent and transiently elevated expression of a cytoplasmic 32 kDa protein was observed in Swiss albino 3T3 fibroblasts exposed to mainstream cigarette smoke (CS) trapped in phosphate-buffered saline solutions (smoke-bubbled PBS). The protein was identified as heme oxygenase (HO) (heme, hydrogen donor:oxygen oxidoreductase, EC 1.14.99.3) by Western blotting using an anti-rodent HO-specific antibody. Kinetic investigations revealed that HO protein and its mRNA were detectable in smoke-bubbled PBS-treated cells between 1 and 24 h after exposure to 0.03 puffs (approximately 1 cm3) CS per ml medium. As a result of transcriptional activation, a nearly 50-fold increase in the amount of HO mRNA was determined after 8 h exposure compared to control levels. Since literature data indicate that there is a link between glutathione depletion and HO expression, the same was assumed for cells exposed to smoke-bubbled PBS, as a decrease of more than 60% in glutathione levels was observed after the exposure. This was further supported by the observation that no elevated amounts of HO mRNA appeared in smoke-bubbled PBS-treated cells when cysteine was exogenously added. However, although these effects may be attributable to the formation of hydroxyl radicals (which have been shown to induce HO and to deplete glutathione levels and which appear in aqueous smoke-containing solutions via the iron-catalysed Fenton reaction) neither catalase nor the iron cation chelating agent o-phenanthroline were able to suppress or even to reduce HO expression in smoke-bubbled PBS-treated cells. On the contrary, at comparable concentrations both compounds were found to be potent inhibitors of smoke-dependent DNA strand breaks. Hence, reactive species other than Fenton reaction-derived hydroxyl radicals are responsible for the effects observed in the present study.
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PMID:Heme oxygenase expression in Swiss 3T3 cells following exposure to aqueous cigarette smoke fractions. 829 50

Process parameters using a Microfluidizer M110 to produce liposome-encapsulated hemoglobin (LEH) were further studied to examine their effect on hemoglobin (Hb) encapsulation efficiency (yield), steady shear viscosity, mechanical stability, and oxygen delivery. Liposome formulation loading ratios of up to 300 mumol of lipid per ml of Hb solution were evaluated; a maximum yield was obtained at 300 mumol/ml. Liposomes containing encapsulated Hb concentrations as high as 15.5 g/100 ml were prepared. LEH particle size distribution, determined from negatively stained whole mount preparations using transmission electron microscopy, resulted in average vesicle sizes for optimal batches of about 155 nm. Steady shear viscosity of LEH (up to 40% by volume) in an isotonic-isooncotic solution of PBS containing either albumin or dextran were evaluated for shear rates to 2000 s-1. Values obtained were generally higher than those of whole blood at all shear rates tested. Little leakage of Hb from liposomes stored in isotonic PBS was observed as a function of storage time and shear rate. Administration of LEH supported life in rats whose hematocrit had been reduced via isovolemic exchange transfusion to levels well below 5%, which was incompatible with survival when exchange transfusion was performed with the isotonic-isooncotic PBS solution.
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PMID:Liposome-encapsulated hemoglobin using film hydration processing to form artificial red blood cells. 831 8

Oxidation of lipids and lipoproteins by macrophages is an important event during atherogenesis. Activation of monocytic cells by zymosan and other agonists results in the release of multiple oxidant species and consequent oxidation of LDL. We now show evidence that ceruloplasmin, a copper-containing acute phase reactant, is secreted by zymosan-activated U937 monocytic cells, and that the protein has an important role in LDL oxidation by these cells. In one approach, ceruloplasmin has been shown to exhibit oxidant activity under the appropriate conditions. Exogenous addition of purified human ceruloplasmin stimulates U937 cell oxidation of LDL to nearly the same extent as activation by zymosan. In contrast to previous cell-free experiments (Ehrenwald, E., G.M. Chisom, and P.L. Fox. 1994. Intact human ceruloplasmin oxidatively modifies low density lipoprotein. J. Clin. Invest. 93:1493-1501.) in which ceruloplasmin by itself (in PBS) oxidizes LDL, under the conditions of the current experiments (in RPMI 1640 medium) ceruloplasmin only oxidizes LDL in the presence of cells; the mechanism by which cells overcome the inhibition by medium components has not been ascertained. As further evidence for a role of ceruloplasmin, activation of U937 cells with zymosan induces ceruloplasmin mRNA and ceruloplasmin protein synthesis after a 5-6 h lag that is consistent with that preceding LDL oxidation. Finally, neutralization by a highly specific polyclonal antibody to human ceruloplasmin inhibits LDL oxidation by at least 65%. Moreover, multiple antisense oligodeoxynucleotides targeted to different regions of the ceruloplasmin mRNA block LDL oxidation by up to 95%. The specific action of the antisense oligonucleotides has been verified by showing inhibition of ceruloplasmin synthesis and by the ability of exogenous ceruloplasmin to overcome the inhibition. In summary, these results are consistent with a mechanism in which cell-derived ceruloplasmin participates in oxidation of LDL by U937 monocytic cells. The data also show that cellular factors in addition to ceruloplasmin, possibly active oxygen species and/or lipoxygenases, are essential and act synergistically with ceruloplasmin to oxidize LDL.
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PMID:Role of endogenous ceruloplasmin in low density lipoprotein oxidation by human U937 monocytic cells. 860 49

Carbon fibre micro-electrodes have been used to determine the influence of temperature and physiological media on the oxidation potential value of three carboxylic acids of physiological interest such as ascorbate (AA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindolacetic acid (5HIAA). Standard calibrations at room temperature (18-20 degrees C) in phosphate buffered saline (PBS, pH 7.4), in Krebs (pH 7.4) or in artificial cerebral spinal fluid (ACSF, pH 7.4) have been compared with calibrations performed at 37 degrees C under 95% oxygen, 5% carbon dioxide. Ex vivo experiments were then performed with the electrode inserted in the striatum of rat brain slices maintained in ACSF at 37 degrees C under 95% oxygen, 5% carbon dioxide. The results obtained from both in vitro and ex vivo experimentation indicate that the oxidation potential of peak 2 (DOPAC) is highly sensitive to changes in temperature and medium. Therefore the extrapolation from in vitro electrode calibrations performed in PBS at room temperature to ex vivo (brain slices) and possibly in vivo measurements of DOPAC oxidation should be reconsidered.
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PMID:Carbon fibre micro-electrode and in vitro or in brain slices voltammetric measurement of ascorbate, catechol and indole oxidation signals: influence of temperature and physiological media. 863 82

Nitric oxide (NO) is a free radical produced enzymatically in biological systems from the guanidino group of L-arginine. Its large spectrum of biological effects is achieved through chemical interactions with different targets including oxygen (O2), superoxide (O2o-) and other oxygen reactive species (ROS), transition metals and thiols. Superoxide anions and other ROS have been reported to react with NO to produce peroxynitrite anions that can decompose to form nitrogen dioxide (NO2) and hydroxyl radial (OHo). Thus, NO has been reported to have a dual effect on lipid peroxidation (prooxidant via the peroxynitrite or antioxydant via the chelation of ROS). In the present study we have investigated in different models the in vitro and in vivo action of NO on lipid peroxidation. Copper-induced LDL oxidation were used as an in vitro model. Human LDL (100 micrograms ApoB/ml) were incubated in oxygene-saturated PBS buffer in presence or absence of Cu2+ (2.5 microM) with increasing concentrations of NO donnors (sodium nitroprussiate or nitroso-glutathione). LDL oxidation was monitored continuously for conjugated diene formation (234 nm) and 4-hydroxynonenal (HNE) accumulation. Exogenous NO prevents in a dose dependent manner the progress of copper-induced oxidation. Ischaemia-reperfusion injury (I/R), characterized by an overproduction of ROS, is used as an in vivo model. Anaesthetized rats were submitted to 1 hour renal ischaemia following by 2 hours of reperfusion. Sham-operated rats (SOP) were used as control. Lipid peroxidation was evaluated by measuring the HNE accumulated in rats kidneys in presence or absence of L-arginine or D-arginine infusion. L-arginine, but not D-arginine, enhances HNE accumulation in I/R but not in SOP (< 0.050 pmol/g tissue in SOP versus 0.6 nmol/g tissue in I/R), showing that, in this experimental conditions, NO produced from L-arginine, enhances the toxicity of ROS. This study shows that the pro- or antioxydant effects of NO are different in vivo and in vitro and could be driven by environmental conditions such as pH, relative concentrations of NO and ROS, ferryl species.
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PMID:[Nitric oxide and lipid peroxidation]. 867 27

Some aspects of a defense against an oxidative stress are reviewed. All these aspects are focused on the necessity to defend mtDNA against damage. Protecting mechanisms involve the regulation of mitochondrial transport of nucleic acids, and the development of antioxygen defense as preventive measures. In the first case an exclusive role is supposed to play the mitochondrial benzodiazepine receptor and components, regulating the activity of its participants (mitochondrial porin and adenine nucleotide translocator). The possible transport of nucleic acids through Ca(2+)-dependent permeability transition pore, representing one of the functional states of mitochondrial benzodiazepine receptor, is put forth. Such mechanisms can also cover the genomic nuclear-mitochondrial exchange. The second aspect reviews the possible complex of measures to lower the harmful effect of oxygen. Among these measures are mild uncoupling, the opening of a permeability transition pore and cellular apoptosis as was recently suggested by Skulachev. Problems such as cellular aging and mitochondrial diseases, are discussed in light of the relevance to the problem of oxidative stress.
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PMID:Mitochondrial damage as a source of diseases and aging: a strategy of how to fight these. 868 40

Developmental immaturities in neonatal host defense predispose the neonates to an increased mortality rate during bacterial infections. Early diagnosis is of great clinical importance, but, especially in neonates, is sometimes very difficult. The ability to generate reactive oxygen species, the so-called respiratory burst, is essential for neutrophils to kill infectious microorganisms. Therefore, changes of respiratory burst may reflect increased susceptibility of neonates to infections and may be useful for the early detection of infections. Superoxide anion production was determined by a flow cytometric method using dihydrorhodamine 123 (DHR) as an oxidative probe after priming of neutrophils with PBS buffer (spontaneous burst), with N-formyl-methionyl-leucyl-phenylalanine (fMLP), or with Escherichia coli. During the study period, the spontaneous percentage of activated cells in whole blood as well as the percentage of activated cells in stimulation with fMLP was lower in adults (n = 100; PBS, 1.0 +/- 0.1%; fMLP, 8.3 +/- 0.9%) compared with neonates without signs of infection (n = 143). Among the latter, the percentage of activated cells (PBS and fMLP assay) varied with respect to gestational age and hours of life: lowest values were measured in preterm newborns with gestational age less than 32 wk and between 25 and 120 h of life. The same correlation to gestational age was true for total neutrophil cell counts. In neonates with increased levels of C-reactive protein during the first 5 d of life (n = 43), the percentages of activated cells after PBS and fMLP incubation were higher than those of neonates without signs of infection. The relationship of neutrophil respiratory burst and neutrophil cell counts to gestational age might reflect at least in part a reason for the increased susceptibility of neonates to infections. Furthermore, determination of respiratory burst may prove to be a new laboratory parameter of neonatal infection.
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PMID:Neutrophil respiratory burst in term and preterm neonates without signs of infection and in those with increased levels of C-reactive protein. 872 39

The lethal effect of near ultraviolet (NUV) with low intensity on cultured RPE cells has been investigated. RPE cultures with various cell densities were exposed to NUV (peaking at 365 nm) with or without ambient oxygen in phenol-red-free Dulbecco's PBS containing Ca2+, Mg2+ and glucose (PBS+). The cell viability was determined by dye exclusion and was expressed as cell death ratio (CDR, dead cells/total cells). When RPE cells at 5 x 10(3) cells/cm2, a non-contact low density, were irradiated either at a fixed irradiance (900 microW/cm2) with different exposure times (4 to 8h) or vice versa (8 h with irradiance from 430 to 900 microW/cm2), the change of CDR represented a similar linear function. The replotted data from both the time- and the irradiance-dependent curves indicated that the killing of RPE cells is dependent on the total energy dose of NUV. When a single NUV energy (19.44 J/cm2) was used, CDR was RPE cell density dependent. At confluence, NUV at the highest dosage tested (26 J/cm2) did not show any lethality. An oxygen-free condition abolished the NUV lethality on RPE cells even though the RPE cells were at a non-contact state. The presence of an antioxidant enzyme, catalase, in oxygen-saturated PBS+ protected RPE cells against NUV killing, but superoxide dismutase did not protect the RPE cells against NUV killing. These findings demonstrate that NUV possesses a lethal effect on RPE cells in vitro. Two key factors determine the magnitude and nature of this lethal effect: first, total NUV energy dose determines the nature of NUV's lethal effect; second, RPE growth conditions suggest the importance of cell-cell interaction in protecting these cells from NUV injury. Because an oxygen-free condition abolishes NUV lethality, it suggests that the oxidative stress is directly related to NUV lethal action. The selective inhibition by catalase of NUV killing of RPE cells suggests that the killing is oxidative species specific. NUV radiation might be highly risky to RPE viability in vivo, especially when the integrity of the RPE layer has been lost.
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PMID:Characterization of lethal action of near-ultraviolet on retinal pigment epithelial cells in vitro. 897 37


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