Optimization of nisin production by Lactococcus lactis UQ2 using supplemented whey as alternative culture medium.

Lactococcus lactis UQ2 is a nisin A-producing native strain. In the present study, the production of nisin by L. lactis UQ2 in a bioreactor using supplemented sweet whey (SW) was optimized by a statistical design of experiments and response surface methodology (RSM). In a 1st approach, a fractional factorial design (FFD) of the order 2(5-1) with 3 central points was used. The effect on nisin production of air flow, SW, soybean peptone (SP), MgSO(4)/MnSO(4) mixture, and Tween 80 was evaluated. From FFD, the most significant factors affecting nisin production were SP (P = 0.011), and SW (P = 0.037). To find optimum conditions, a central composite design (CCD) with 2 central points was used. Three factors were considered, SW (7 to 10 g/L), SP (7 to10 g/L), and small amounts of added nisin as self-inducer (NI 34.4 to 74.4 IU/L). Nisin production was expressed as international units (IU). From RSM, an optimum nisin activity of 180 IU/mL was predicted at 74.4 IU/L NI, 13.8 g/L SP, and 14.9 or 5.11 g/L SW, while confirmatory experiments showed a maximum activity of 178 +/- 5.2 IU/mL, verifying the validity of the model. The 2nd-order model showed a coefficient of determination (R(2)) of 0.828. Optimized conditions were used for constant pH fermentations, where a maximum activity of 575 +/- 17 IU/mL was achieved at pH 6.5 after 12 h. The adsorption-desorption technique was used to partially purify nisin, followed by drying. The resulting powder showed an activity of 102150 IU/g. Practical Application: Nisin production was optimized using supplemented whey as alternative culture medium, using a native L. lactis UQ2 strain. Soybean peptone, SW, and subinhibitory amounts of nisin were successfully employed to optimize nisin production by L. lactis UQ2. Dried semipurified nisin showed an activity of 102150 IU/g.

Monitorización de presiones en técnicas continuas de depuración extrarrenal / Pressure monitoring in continuous renal replacement therapy

IntroducciónLas técnicas de depuración extrarrenal han obtenido grandes avances que han conseguido una ampliación de las indicaciones y una mejora en la tecnología de la monitorización continua de las presiones.ObjetivoEl objetivo del estudio es conocer si existe asociación entre el aumento de las presiones de los circuitos y la duración de éstos.Material y métodosEstudio analítico longitudinal prospectivo, realizado en una unidad de cuidados intensivos polivalente de un hospital terciario, desde octubre de 2008 hasta abril de 2009. Se recogieron datos de filiación de pacientes con técnicas de depuración extrarrenal y valores horarios de: presión de entrada (PE), presión de retorno (PR), presión transmembrana (PTM) y presión prefiltro (PPF). Se utilizó la correlación de Spearman y T de Student.ResultadosSe analizaron 44 sets correspondientes a 11 pacientes (el 45,5% eran hombres y el 54,5% eran mujeres) con un media de edad de 62 años. Se utilizó el mismo catéter de doble luz: GamCath (11 Fr) y la misma terapia: hemodiafiltración venovenosa continua. La media de duración de los circuitos fue de 39h. Los valores de media, mediana, máximo y mínimo de las presiones de la muestra fueron: (-52,17; -52,57; 160 y -256 [milímetros de mercurio] mmHg), PR (98,6; 95,3; 323 y -2mmHg), PTM (58,57; 58,52; 245 y -20mmHg) y PPF (161,76; 159,42; 375 y -13mmHg), respectivamente. Conclusiones: Se demuestra correlación negativa entre la duración de los sets y la media de PR y de PPF. Conclusiones: La muestra obtenida incluía tanto circuitos retirados por tratamiento completo (72h) como por coagulación o cambio en presiones

IntroductionContinuous renal replacement therapy (CRRT) has experienced significant advances that have lead to an increase of its indications and improved the technology used in continued pressures monitoring.AimThis study has aimed to discover if there are any associations between the increase of the circuit pressures and their duration.Materials and methodsA prospective, longitudinal analytic pilot study was conducted in an Intensive Care Unit of a university hospital from October 2008 to April 2009. The study analyzed the patient's information with CRRT and the hourly values of entry pressure (EP), comeback pressure (CP), transmembrane pressure (TMP) and pre-filter pressure (PFP). The Spearman correlation and the Student's T test were used.ResultsThe study analyzed 44 sets corresponding to 11 patients (45.5% men and 54.5% women) with a life expectancy of 62 years. The same light catheter GamCath (11 French) and Continuous Venovenous Hemodiafiltration (CVVHDF) therapy were used in all patients. The mean duration of the circuits was 39h. Mean, median, maximum and minimum values of the sample pressures were: EP:−52.17; −52.57; 160; −256 (millimeters of mercury) mmHg]; CP: (98.6; 95.3; 323; −2mmHg); TMP: (58.57; 58.52; 245; −20mmHg) and PFP: (161.76; 159.42; 375; −13mmHg), respectively.ConclusionsA negative correlation was demonstrated between the duration of the sets and the mean CP and PFP. The sample obtained circuits withdrawn due to finished treatment (72h), and by coagulation or changes in pressures(AU)

[Pressure monitoring in continuous renal replacement therapy]. / Monitorización de presiones en técnicas continuas de depuración extrarrenal.

INTRODUCTION: Continuous renal replacement therapy (CRRT) has experienced significant advances that have lead to an increase of its indications and improved the technology used in continued pressures monitoring. AIM: This study has aimed to discover if there are any associations between the increase of the circuit pressures and their duration. MATERIALS AND METHODS: A prospective, longitudinal analytic pilot study was conducted in an Intensive Care Unit of a university hospital from October 2008 to April 2009. The study analyzed the patient's information with CRRT and the hourly values of entry pressure (EP), comeback pressure (CP), transmembrane pressure (TMP) and pre-filter pressure (PFP). The Spearman correlation and the Student's T test were used. RESULTS: The study analyzed 44 sets corresponding to 11 patients (45.5% men and 54.5% women) with a life expectancy of 62 years. The same light catheter GamCath (11 French) and Continuous Venovenous Hemodiafiltration (CVVHDF) therapy were used in all patients. The mean duration of the circuits was 39 h. Mean, median, maximum and minimum values of the sample pressures were: EP:-52.17; -52.57; 160; -256 (millimeters of mercury) mmHg]; CP: (98.6; 95.3; 323; -2 mmHg); TMP: (58.57; 58.52; 245; -20 mmHg) and PFP: (161.76; 159.42; 375; -13 mmHg), respectively. CONCLUSIONS: A negative correlation was demonstrated between the duration of the sets and the mean CP and PFP. The sample obtained circuits withdrawn due to finished treatment (72 h), and by coagulation or changes in pressures.