Effect of Sodium Nitrite, Sodium Chloride, and Sodium Nitrate on Germination and Outgrowth of Anaerobic Spores

The effects of meat-curing agents on germination and outgrowth of putrefactive anaerobe 3679h (PA 3679h) spores were studied in microcultures. Nitrite concentrations up to 0.06% at pH 6.0 or between 0.8 and 1% at pH 7.0 allowed emergence and elongation of vegetative cells but blocked cell division. The newly emerged cells then lysed. With more than 0.06% nitrite at pH 6.0 or more than 0.8 to 1% at pH 7.0, the spores lost refractility and swelled, but vegetative cells did not emerge. Even as much as 4% nitrite failed to prevent germination (complete loss of refractility) and swelling of the spores. Sodium chloride concentrations above 6% prevented complete germination (i.e., the spores retained a refractile core). In the presence of 3 to 6% sodium chloride, most of the spores germinated and produced vegetative cells, but cell division was often blocked. Sodium nitrate had no apparent effect on germination and outgrowth at concentrations up to 2%.     

Effect of pH, Sodium Chloride, and Sodium Nitrite on Enterotoxin A Production

The combined effects of pH, sodium chloride, and sodium nitrite were studied by using a dialysis sac technique in brain heart infusion broth. Growth and enterotoxin A production by Staphylococcus aureus strain 100 were found to decrease with the addition of sodium nitrite, with a decrease in pH from 7.0, and with an increase in sodium chloride concentration. The significance of these results is discussed in relation to cured meats.     

Sodium Acetate,Sodium Acid Pyrophosphate,and Citric Acid Impacts on Isolated Peripheral Lymphocyte Viability,Proliferation, and DNA Damage

The present study examined the impacts of sodium acetate (SA), sodium acid pyrophosphate (SAPP), and citric acid (CA) on the viability, proliferation, and DNA damage of isolated lymphocytes in vitro. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays were adopted to evaluate cell viability, while comet assay was employed to assess the genotoxic effects. The cells were incubated with different levels of SA (50, 100, and 200 mM), SAPP (25, 50, and 100 mM/L), or CA (100, 200, and 300 μg/mL). The lymphocytes treated with the tested food additives showed concentration‐dependent decreases in both cell viability and proliferation. A concentration‐dependent increase in LDH release was also observed. The comet assay results indicated that SA, SAPP, and CA increased DNA damage percentage, tail DNA percentage, tail length, and tail moment in a concentration‐dependent manner. The current results showed that SA, SAPP, and CA are cytotoxic and genotoxic to isolated lymphocytes in vitro.     

Sodium channels: grit, determination, and persistence

Persistent sodium channel activity modulates neuronal gain in a neurotransmitter-dependent fashion. Previous studies have suggested that persistent and spike-related sodium channel activities are mediated by separate species. In this issue of Neuron, Taddese and Bean (2002) show that a single channel population is sufficient to explain both gating behaviors. A simple allosteric model is provided that can explain the results.     

Sodium,Potassium-ATPases in Algae and Oomycetes

We have investigated the presence of K⁺-transporting ATPases that belong to the phylogenetic group of animal Na⁺,K⁺-ATPases in the Pythium aphanidermatum Stramenopile oomycete, the Porphyra yezoensis red alga, and the Udotea petiolata green alga, by molecular cloning and expression in heterologous systems. PCR amplification and search in EST databases allowed one gene to be identified in each species that could encode ATPases of this type. Phylogenetic analysis of the sequences of these ATPases revealed that they cluster with ATPases of animal origin, and that the algal ATPases are closer to animal ATPases than the oomycete ATPase is. The P. yezoensis and P. aphanidermatum ATPases were functionally expressed in Saccharomyces cerevisiae and Escherichia coli alkali cation transport mutants. The aforementioned cloning and complementary searches in silicio for H⁺- and Na⁺,K⁺-ATPases revealed a great diversity of strategies for plasma membrane energization in eukaryotic cells different from typical animal, plant, and fungal cells.     

Cerebrovascular Permeability Coefficients to Sodium, Potassium, and Chloride

CSF and regional brain concentrations of 42K, 22Na, 36Cl, and [14C]mannitol were determined 3-45 min after intravenous injection of the tracers in pentobarbital-anesthetized rats. Rapid influx of 36Cl and 22Na into ventricular CSF immediately established concentration gradients from CSF to brain extracellular fluid. The CSF contribution to brain uptake of tracers was greatest in periventricular brain regions, where brain 36Cl concentrations were up to ninefold higher than concentrations in regions distant from ventricular CSF. Acetazolamide (20 mg kg-1 i.p.), an inhibitor of CSF formation, decreased 36Cl uptake into CSF and into periventricular brain regions but not into frontal cortex. 36Cl uptake into brain was unidirectional for 10 min after intravenous injection, and, during that period, diffusion from ventricular CSF did not contribute to uptake in the frontal cortex. Therefore, cerebrovascular permeability coefficients could be calculated from tracer concentrations in frontal cortex at 10 min and equaled, in cm s-1, 13.5 X 10(-7) for 42K, 1.4 X 10(-7) for 22Na, 0.9 X 10(-7) for 36Cl, and 1.5 X 10(-7) for [14C]mannitol. The low cerebrovascular permeabilities to K, Na, and Cl, comparable to those of some cell membranes, and the permselectivity (K much greater than Na greater than Cl) suggest that a significant fraction of ion transport across cerebral capillaries is transcellular, i.e., across the endothelial cell membrane.     

Predictive Thermal Inactivation Model for Effects of Temperature, Sodium Lactate, NaCl, and Sodium Pyrophosphate on Salmonella Serotypes in Ground Beef

Analyses of survival data of a mixture of Salmonella spp. at fixed temperatures between 55°C (131°F) and 71.1°C (160°F) in ground beef matrices containing concentrations of salt between 0 and 4.5%, concentrations of sodium pyrophosphate (SPP) between 0 and 0.5%, and concentrations of sodium lactate (NaL) between 0 and 4.5% indicated that heat resistance of Salmonella increases with increasing levels of SPP and salt, except that, for salt, for larger lethalities close to 6.5, the effect of salt was evident only at low temperatures (<64°C). NaL did not seem to affect the heat resistance of Salmonella as much as the effects induced by the other variables studied. An omnibus model for predicting the lethality for given times and temperatures for ground beef matrices within the range studied was developed that reflects the convex survival curves that were observed. However, the standard errors of the predicted lethalities from this models are large, so consequently, a model, specific for predicting the times needed to obtained a lethality of 6.5 log₁₀, was developed, using estimated results of times derived from the individual survival curves. For the latter model, the coefficient of variation (CV) of predicted times range from about 6 to 25%. For example, at 60°C, when increasing the concentration of salt from 0 to 4.5%, and assuming that the concentration of SPP is 0%, the time to reach a 6.5-log₁₀ relative reduction is predicted to increase from 20 min (CV = 11%) to 48 min (CV = 15%), a 2.4 factor (CV = 19%). At 71.1°C (160°F) the model predicts that more than 0.5 min is needed to achieve a 6.5-log₁₀ relative reduction.     

十二烷基硫酸钠与十二烷基磺酸钠

十二皖基硫酸钠与十二垸基磺酸钠的混淆及误用具育一定的普遍性。两虽均属于阴离子表面活性剂但结构及理化性质均育所差别,因此在实验中予以一定的关注是必要的。     

Anticomplementary, Anticoagulatory, and Serum-Protein Precipitating Activity of Sodium Polyanetholsulfonate

Sodium polyanetholsulfonate (SPS) at 7.8 mug/ml completely abolished complement-mediated hemolysis of 1:10 diluted fresh guinea pig and human serum; at least twice as much SPS was required to reduce complement activity in 1:2 diluted human serum. The coagulation of 90 and 20% human blood was inhibited by 250 and 125 mug of SPS per ml, respectively. When added to fresh human serum, SPS precipitated beta 1C-globulin (C3), C4, beta lipoproteins, immunoglobulin IgG, IgM, and IgA, though incompletely.     

Sodium,protons, and energy coupling in the methanogenic bacteria

In this review, I focus on the bioenergetics of the methanogenic bacteria, with particular attention directed to the roles of transmembrane electrochemical gradients of sodium and proton. In addition, the mechanism of coupling ATP synthesis to methanogenic electron transfer is addressed. Evidence is reviewed which suggests that the methanogens possess great diversity in their bioenergetic machinery. In particular, in some methanogens the primary ion which is translocated coupled to metabolic energy is the proton, while others appear to utilize sodium. In addition, ATP synthesis driven by methanogenic electron transfer is accomplished in some organisms by a chemiosmotic mechanism and is coupled by a more direct mechanism in others. A possible explanation for this diversity (which is consistent with the relatedness of these organisms to each other and to other members of the Archaebacteria as determined by molecular biological techniques) is discussed.     

Sodium transport defect of ouabain-resistant renal Na,K-ATPase

The murine renal Na,K-ATPase is resistant to cardiac glycosides. It is not yet known however whether altered active transport is associated with the drug-resistance. To investigate this problem Na,K-ATPases were purified from the outer medulla of both rat and rabbit kidneys and reconstituted identically into liposomes. The Na-stimulation of the Na,K-ATPase activity before reconstitution and of the Na-transport after reconstitution was measured. A Na-defect inherent in the ouabain-resistant rat Na,K-ATPase was discovered indicating a link between the cardiac glycoside sensitivity and the Na-transport.     

Sodium dodecyl sulfate, concurrent inhibitor of several dehydrogenases

The effect of sodium dodecyl sulfate on the activity of highly purified or crystalline enzymes has been studied. The enzymes were: lactate dehydrogenase (LDH), malate dehydrogenase (MDH). isocitrate dehydrogenase (ICDH), glucose-6-phosphate dehydrogenase (G6P-DH), lipase, alkaline phosphatase. Sodium dodecyl sulfate, always under the critical micellar concentration, shows a selective inhibitory effect. A kinetic analysis of the inhibitory action on LDH, MDH, ICDH and G6P-DH was also carried out.