Efectos de la sal sobre la solubilidad y las propiedades emulsionantes de la caseína y sus hidrolizados trípticos

This work reports an investigation about the effect of NaCl addition (0.02 mol/L) on some functional properties of casein(CA) and its tryptic hydrolysates (TH). The solubility, the emulsifying capacity (EC), the emulsifying activity index(EAI) and the emulsion stability (ES) were determined at two pH values (4.0 and 5.0). The results showed that thisprocedure was benefi cial for the solubility of CA and TH, being more intense at pH 5.0 and 4.0, respectively. Also, apositive effect of NaCl addition was observed for CA and TH, at both pH values, and the best results for both sampleswere achieved at pH 5.0. The ES was slightly affected by the presence of salt and only for some samples of CA andTH it was increased. Contrarily, the EAI values of casein were reduced with the addition of NaCl at pH 4.0 and 5.0,while those of TH were positively affected by this treatment at both pH values.En este trabajo se presentan los resultados de una investigación sobre los efectos de la adición de NaCl (0,02 mol/L)sobre algunas propiedades funcionales de la caseína (CA) y de sus hidrolizados trípticos (TH). Se determinaron lasolubilidad, la capacidad emulsionante (CE), el índice de actividad emulsionante (IAE) y la estabilidad de la emulsión(EE) con dos valores de pH (4,0 y 5,0). Los resultados demostraron que el procedimiento era benefi cioso parala solubilidad de CA y TH, siendo más intensa con pH 5,0 y 4,0, respectivamente. También se observó un efectopositivo de la adición de NaCl en CA y TH, con ambos valores de pH, consiguiéndose los mejores resultados conpH 5,0. La EE se vio ligeramente afectada por la presencia de sal, y sólo aumentó en algunas muestras de CA yTH. Por el contrario, los valores del IAE de la caseína se redujeron al añadir NaCl con pH 4,0 y 5,0, mientras quelas de TH se vieron afectadas positivamente por este tratamiento con ambos valores de pH

Utilización de dos soportes para la inmovilización de la papaína

Papain was immobilized on activated carbon (AC) and on alumina (AL), with the aim of preparing low cost dietarysupplements, using whey as hydrolysed protein source. The quantifi cation of the non-adsorbed enzyme, using Lowry’smethod was used to determine the immobilization rate. The effect of the contact time and the temperature was tested,and 30 min at 250C was considered the best condition for immobilizing papain in both supports. AC showed muchhigher immobilization rates (from 95% to 99%) than AL (from 4% to 13%). The reusability of papain was evaluated bymeasuring the residual activity of the enzyme after it has been used for up to 20 times. The quantifi cation of exposurerate of phenylalanine by second derivative spectrophotometry was used to determine the enzyme activity. In this case, ALshowed better results than AC, since the activity of papain remained unchanged after 15 and 5 times, respectively.Con la intención de preparar suplementos dietéticos de bajo coste, se inmovilizó papaína en carbón activado (CA) yen alúmina, utilizando suero como fuente de proteínas hidrolizadas. Para determinar el índice de inmovilización secuantifi caron las enzimas no adsorbidas mediante el método de Lowry. Se analizó el efecto del tiempo de contactoy la temperatura, considerándose 30 min. a 25 ºC como la condición óptima para inmovilizar la papaína en ambossoportes. El CA presentó unos índices de inmovilización muy superiores (entre 95% y 99%) a los de la AL (entre4% y 13%). Para evaluar la capacidad de reutilización de la papaína se midió la actividad residual de la enzimadespués de haber sido utilizada hasta 20 veces. Para determinar la actividad de la enzima se cuantifi có el índice deexposición de la fenilalanina mediante espectrofotometría de derivada segunda. En este caso, la AL presentó mejoresresultados que el CA, ya que la actividad de la papaína seguía siendo la misma después de haber sido utilizada 15y 5 veces, respectivamente

Experimental Evolution of Resistance to Artemisinin Combination Therapy Results in Amplification of the mdr1 Gene in a Rodent Malaria Parasite

Background: Lacking suitable alternatives, the control of malaria increasingly depends upon Artemisinin Combination Treatments (ACT): resistance to these drugs would therefore be disastrous. For ACTs, the biology of resistance to the individual components has been investigated, but experimentally induced resistance to component drugs in combination has not been generated. Methodology/Principal Findings: We have used the rodent malaria parasite Plasmodium chabaudi to select in vivo resistance to the artesunate (ATN) + mefloquine (MF) version of ACT, through prolonged exposure of parasites to both drugs over many generations. The selection procedure was carried out over twenty-seven consecutive sub-inoculations under increasing ATN + MF doses, after which a genetically stable resistant parasite, AS-ATNMF1, was cloned. AS-ATNMF1 showed increased resistance to ATN + MF treatment and to artesunate or mefloquine administered separately. Investigation of candidate genes revealed an mdr1 duplication in the resistant parasites and increased levels of mdr1 transcripts and protein. There were no point mutations in the atpase6 or ubp1genes. Conclusion: Resistance to ACTs may evolve even when the two drugs within the combination are taken simultaneously and amplification of the mdr1 gene may contribute to this phenotype. However, we propose that other gene(s), as ye

EFFECTS OF VITAMIN C SUPPLEMENTATION ON THE CHRONIC PHASE OF CHAGAS DISEASE

Introduction: In order to examine the effectiveness of vitamin C (ascorbic acid) in combating the oxidative insult caused by Trypanosoma cruzi during the development of the chronic phase of Chagas disease, Swiss mice were infected intraperitoneally with 5.0 × 104 trypomastigotes of T. cruzi QM1strain. Methods: Mice were given supplements of two different doses of vitamin C for 180 days. Levels of lipid oxidation (as indicated by thiobarbituric acid reactive substances-TBARS), total peroxide, vitamin C, and reduced glutathione were measured in the plasma, TBARS, total peroxide and vitamin C were measured in the myocardium and histopathologic analysis was undertaken in heart, colon and skeletal muscle. Results: Animals that received a dose equivalent to 500 mg of vitamin C daily showed increased production of ROS in plasma and myocardium and a greater degree of inflammation and necrosis in skeletal muscles than those that received a lower dose or no vitamin C whatsoever. Conclusion: Although some research has shown the antioxidant effect of vitamin C, the results showed that animals subject to a 500 mg dose of vitamin C showed greater tissue damage in the chronic phase of Chagas disease, probably due to the paradoxical actions of the substance, which in this pathology, will have acted as a pro-oxidant or pro-inflammatory