Antibacterial efficacy of nisin, bacteriophage P100 and sodium lactate against Listeria monocytogenes in ready-to-eat sliced pork ham

ABSTRACT The effectiveness of bacteriophage P100, nisin and sodium lactate, individually and in combination, in inhibiting Listeria monocytogenes in ready-to-eat pork ham slices was assessed. The antimicrobials were applied to the surfaces of ready-to-eat pork ham slices, which were inoculated with a mixture of L. monocytogenes. Among the individual antimicrobial treatments, bacteriophage P100 was the most effective, decreasing L. monocytogenes to undetectable levels at zero and 72 h post-infection. Sodium lactate was the least effective treatment. Treatment with nisin at zero h significantly reduced initial cell density (p < 0.05). However, this pattern was not observed at 72 h of storage. A significant difference (p < 0.05) existed between the results of separate bacteriophage and nisin treatments after refrigerated storage, but not immediately upon inoculation of the bacteria. The results showed that the use of bacteriophage P100 is the method of choice for the control of bacteria.

Antibacterial efficacy of nisin, bacteriophage P100 and sodium lactate against Listeria monocytogenes in ready-to-eat sliced pork ham.

The effectiveness of bacteriophage P100, nisin and sodium lactate, individually and in combination, in inhibiting Listeria monocytogenes in ready-to-eat pork ham slices was assessed. The antimicrobials were applied to the surfaces of ready-to-eat pork ham slices, which were inoculated with a mixture of L. monocytogenes. Among the individual antimicrobial treatments, bacteriophage P100 was the most effective, decreasing L. monocytogenes to undetectable levels at zero and 72h post-infection. Sodium lactate was the least effective treatment. Treatment with nisin at zeroh significantly reduced initial cell density (p<0.05). However, this pattern was not observed at 72h of storage. A significant difference (p<0.05) existed between the results of separate bacteriophage and nisin treatments after refrigerated storage, but not immediately upon inoculation of the bacteria. The results showed that the use of bacteriophage P100 is the method of choice for the control of bacteria.

Listeria monocytogenes behaviour and quality attributes during sausage storage affected by sodium nitrite, sodium lactate and thyme essential oil.

The effects of the addition of nitrite at 200 ppm (N), sodium lactate 1.5% (L) and thyme essential oil at 100 ppm (T1) on Listeria monocytogenes behaviour and ATPase activity inhibition were evaluated, as well as lipid oxidation through the quantification of malonaldehydes, in sausage stored at 8 ℃ for 41 days and at 30 ℃ for 14 days. The changes in the colour profile were performed during storage time at 8 ℃. Quantitative descriptive sensory analyses were performed after two days at 4 ℃. At 8 ℃, the treatments with the highest inhibition on L. monocytogenes were L and N, without significant differences. In turn, at 30 ℃, the bacterium was most inhibited with treatment L, followed by T1 and N, without significant differences. A 44.1% and 19% inhibition of ATPase activity was detected in L and T1 treatments, respectively. At 8 ℃ and 30 ℃, malonaldehydes content was not different between the treatments. N presented the highest values of a* and concentration of metmyoglobin after 41 days at 8 ℃. The panel detected differences between T1 and N for the aroma in the descriptors spices and herbal.

Calcium Prerinse before Fluoride Rinse Reduces Enamel Demineralization: An in situ Caries Study.

A calcium (Ca) prerinse before a fluoride (F) rinse has been shown to increase oral F levels. We tested the anticaries effect of this combination in a dose-response in situ caries model. In a double-blind, crossover experiment, 10 volunteers carried enamel slabs in palatal appliances for 14 days, during which they rinsed twice/day with one of four rinse combinations: (1) a placebo prerinse (150 mM sodium lactate) followed by a distilled water rinse (negative control); (2) a placebo prerinse followed by a 250 ppm F rinse; (3) a placebo prerinse followed by a 1,000 ppm F rinse, or (4) a Ca prerinse (150 mM Ca, as calcium lactate) followed by a 250 ppm F rinse. Sucrose solution was dripped onto the slabs 8×/day to simulate a high cariogenic challenge. The percent surface hardness loss (%SHL) was significantly lower in the Ca prerinse used with the 250 ppm F rinse group (%SHL = 38.0 ± 21.0) when compared with the F rinse alone (%SHL = 59.5 ± 24.1) and similar to the 1,000 ppm F rinse group (%SHL = 42.0 ± 18.3). Compared with the 250 ppm F rinse, the Ca prerinse increased biofilm fluid F only twice (nonsignificant). However, it greatly increased F in biofilm solids (∼22×). The Ca prerinse had little effect on loosely or firmly bound enamel F. The results showed an increased level of protection against demineralization by the use of a Ca prerinse, which seems to be caused by the enhancement of F concentration in the biofilm.

Inhibitory effect and cell damage on bacterial flora of fish caused by chitosan, nisin and sodium lactate.

The effect of the combined use of chitosan, nisin and sodium lactate on the growth of Listeria innocua, Shewanella putrefaciens and psychrophilic bacteria isolated from fish was investigated in broth by means of minimum inhibitory concentrations (MIC). Furthermore, the sites of cell-injury caused by mentioned antimicrobials and their combinations on L. innocua and S. putrefaciens were studied. MIC of antimicrobial mixtures were evaluated by Berembaum design and check board method. Antimicrobials' sites of injury were investigated by the evaluation of cell constituents' release, cell surface hydrophobicity and differential scanning calorimetry. Results depended on antimicrobial used; several combinations inhibited the growth of L. innocua and S. putrefaciens and all combinations inhibited psychrophilic bacteria. Besides, some mixtures showed synergistic effects. All the mixtures affected ribosomes and DNA of the studied bacteria. Regarding cellular envelope, antimicrobials acted according to the structural characteristics of target microorganisms. Cell damage was higher when antimicrobials were combined, which could explain the observed synergistic effects. This study demonstrates and justifies the synergistic action of chitosan, nisin and sodium lactate on the inhibition of microorganisms related to fish spoilage and remarks the promissory use of the synergic combination of antimicrobials for fish preservation.

Inhibition of Salmonella Enteritidis by cerein 8A, EDTA and sodium lactate.

The ability of the bacteriocin cerein 8A to inhibit Salmonella Enteritidis in combination with EDTA and sodium lactate was investigated. Salmonella Enteritidis was incubated with combinations of cerein 8A (3200AU/mL) and EDTA (20, 50, 100 mmol/L) or sodium lactate (200 mmol/L). All treatments caused a significant reduction in the OD(600) values of Salmonella Enteritidis cultures. The addition of cerein 8A plus EDTA resulted in higher inhibition in comparison with the bacteriocin alone; the greater the concentration of EDTA, the greater the inhibitory effect. The combination of cerein 8A plus 100 mmol/L EDTA results in a more efficient treatment to reduce the number of viable cells of Salmonella Enteritidis. The combination of cerein 8A plus sodium lactate also showed significant inhibition of the indicator organism. Transmission electron microscopy showed damaged cell walls and loss of protoplasmic material in treated cells. The cells of Salmonella Enteritidis treated with cerein 8A plus EDTA appeared more injured. The bacteriocin cerein 8A may be useful to inhibit Gram-negative bacteria, with enhanced effect in combination with chelating agents. Control of Salmonella Enteritidis, a Gram-negative bacterium constantly linked to food outbreaks, addresses an important aspect of food safety.

Fighting by sleep-deprived rats as a possible manifestation of panic: effects of sodium lactate.

Increased fighting is an effect of desynchronized sleep deprivation (DSD) in rats, and recently this behavior has been suggested to be spontaneous panic and equivalent to panic disorder. In the present study we tested this hypothesis by evaluating the effect of sodium lactate on this aggressiveness, because this substance is recognized to induce spontaneous panic attacks in patients. A total of 186 male albino Wistar rats, 250-350 g, 90-120 days of age, were submitted to DSD (multiple platform method) for 0, 4, or 5 days. At the end of the deprivation period the rats were divided into subgroups respectively injected intraperitoneally with 1.86, 2.98 and 3.72 g/kg of 1 M sodium lactate, or 1.86 and 3.72 g/kg of 2 M sodium lactate. The control animals were submitted to the same procedures but received equivalent injections of sodium chloride. Regardless of DSD time, sleep-deprived animals that received sodium lactate presented a significantly higher mean number of fights (0.13 +/- 0.02 fights/min) and a longer mean time spent in confrontation (2.43 +/- 0.66 s/min) than the controls (0.01 +/- 0.006 fights/min and 0.12 +/- 0.07 s/min, respectively; P<0.01, Student t-test). For the sodium lactate group, concentration of the solution and time of deprivation increased the number of fights, with the mean number of fights and mean duration of fighting episodes being greater with the 2.98 g/kg dose using 1 M lactate concentration. These results support the hypothesis that fighting induced by DSD is probably a spontaneous panic manifestation. However, additional investigations are necessary in order to accept this as a promising animal model for studies on panic disorder.

Fighting by sleep-deprived rats as a possible manifestation of panic: effects of sodium lactate

Increased fighting is an effect of desynchronized sleep deprivation (DSD) in rats, and recently this behavior has been suggested to be spontaneous panic and equivalent to panic disorder. In the present study we tested this hypothesis by evaluating the effect of sodium lactate on this aggressiveness, because this substance is recognized to induce spontaneous panic attacks in patients. A total of 186 male albino Wistar rats, 250-350 g, 90-120 days of age, were submitted to DSD (multiple platform method) for 0, 4, or 5 days. At the end of the deprivation period the rats were divided into subgroups respectively injected intraperitoneally with 1.86, 2.98 and 3.72 g/kg of 1 M sodium lactate, or 1.86 and 3.72 g/kg of 2 M sodium lactate. The control animals were submitted to the same procedures but received equivalent injections of sodium chloride. Regardless of DSD time, sleep-deprived animals that received sodium lactate presented a significantly higher mean number of fights (0.13 + or - 0.02 fights/min) and a longer mean time spent in confrontation (2.43 + or - 0.66 s/min) than the controls (0.01 + or - 0.006 fights/min and 0.12 + or - 0.07 s/min, respectively; P<0.01, Student t-test). For the sodium lactate group, concentration of the solution and time of deprivation increased the number of fights, with the mean number of fights and mean duration of fighting episodes being greater with the 2.98 g/kg dose using 1 M lactate concentration. These results support the hypothesis that fighting induced by DSD is probably a spontaneous panic manifestation. However, additional investigations are necessary in order to accept this as a promising animal model for studies on panic disorder

Central thermoregulatory effects of lactate in the toad Bufo paracnemis.

Hypoxia induces a regulated decrease in body temperature (Tb; anapyrexia) in organisms ranging from protozoans to mammals, but very little is known about the mechanisms involved. Several candidates have been suggested to mediate hypoxia-induced anapyrexia, among them lactate, which is a classical compansion of hypoxic stress in vertebrates. The present study was designed to assess the central thermoregulatory effects of lactate in Bujo paracnemis. Toads equipped with a temperature probe were tested over a thermal gradient (10-40 degrees C). Lactate injected systemically (4.0 mmol kg-1) caused a significant reduction of Tb from 24.6 +/- 2.1 to 17.4 +/- 3.9 degrees C. To assess the role of central thermoregulatory mechanisms, a lower dose (0.4 mmol kg-1) of lactate was injected into the fourth cerebral ventricle or systemically. Intracerebroventricular injection of lactate caused a similar decrease in Tb, whereas systemic injection caused no change. The data indicate that lactate may play a role in hypoxia-induced anapyrexia in central rather than peripheral sites.

Disociación de la respuesta de alarma ante una mezcla de cristaloides y coloides en la inducción anestésica en cirugía cardíaca

El objetivo de la investigación fue probar si la administración de líquidos durante la inducción de la anestesia, al restaurar el déficit de agua y expandirel volumen intravascular, atenuaria la respuesta hormonal normalmente producida en cirugía. Se realizó un estudio randomizado controlado, en un centro de atención terciaria, en treinta y seis pacientes programados para cirugía electiva de bypass aorto-coronario. Los criterios- de exclusión fueron: función miocárdica severamente- reducida o disfunción renal conocida. Doce pacientes recibieron 10 ml/kg de solución Ringer (grupo baja dosis de cristaloide LDC), 12 pacientes recibieron 15 ml/kg solución Ringer (grupo alta dosis de cristaloide HDC), y 12 pacientes recibieron una combinación de 10 ml/kg de solución Ringer más 10 ml/kg1 de solución hidroxietil-starch (HES) 450.000 daltons, grado de substitución 0,7 (grupo C-HES), dentro de un período de 20 minutos posterior a la inducción de la anestesia (fentanyl, midazolam, pancuronio). El índice cardíaco y el índice sistólico se incrementaron en 20 por ciento y 15 por ciento en el grupo C-HES mientras de al ADH, la renina y la aldosterona disminuyeron (18 por ciento, 18 por ciento, 43 por ciento) respectivamente, luego de la administración de volumen. Luego de la administración de volumen, los niveles plasmáticos de lso sistemas hormonales llamados a responder ante la deshidratación e hipovolemia disminuyeron en el grupo C-HES. En los otros dos grupos no se presentó ninguna mejoría del estado hemodinámico y las hormonas medidas permanecieron en el mismo nivel observado durante la inducción de la anestesia. No hubo diferencias intergrupales en el volumen total administrado o en l balance hídrico al final de la cirugía. La administración de una combinación de soluciones cristaloides y coloides siguiendo la inducción de la anestesia en pacientes con función ventricular preservada, programados para cirugía cardíaca, conduce a atenuar las respuesta normal de los sistemas hormonales que se observa durante los estados de deshidratación e hipovolemia, en tanto que la restricción de líquidos promueve la actividad de dichos sistemas hormales