Effect of mild hypothermia on renal ischemia/reperfusion injury after cardiopulmonary resuscitation in a swine model

Abstract Purpose: To investigate the effect of intravascular cooling on renal function after resuscitation. Methods: Twenty four pigs were randomized into three groups (n=8 in each group): therapeutic hypothermia group (TH group), normothermia group (NH group) and sham operation group (SHAM group). After 6 minutes of untreated VF, CPR was performed. Upon ROSC, the TH group received the intravascular cooling. The NH and SHAM group did not undergo therapeutic hypothermia. Haemodynamic parameters were recorded. The bloods were analyzed for serum creatinine (sCr), CysC and NGAL. The kidney was surgically removed observe pathologic changes under a light microscope. Results: The sCr increased in both TH and NH groups after ROSC, compared to baseline. Between two groups, the sCr and creatinine clearance (Cc) showed lower level in the TH group. The urine volume per hour in the TH group were higher during cooling. After resuscitation, NGAL and CysC in the NH group were higher than in the TH group. Under the light microscope, compared with the TH group, the renal injury was prominent in the NH group. Conclusion: Mild hypothermia had a protection to renal ischemia reperfusion injury after resuscitation.

Enzyme activity and thermostability of a non-specific nuclease from Yersinia enterocolitica subsp. palearctica by site-directed mutagenesis

Background: To identify the critical amino acid residues that contribute to the high enzyme activity and good thermostability of Yersinia enterocolitica subsp. palearctica (Y. NSN), 15 mutants of Y. NSN were obtained by site-directed mutagenesis in this study. And their enzyme activity and thermostability were assayed. Effect of several factors on the enzyme activity and thermostability of Y. NSN, was also investigated. Results: The results showed that the I203F and D264E mutants retained approximately 75% and 70% enzyme activity, respectively, compared to the wild-type enzyme. In addition to the I203F and D264E mutants, the mutant E202A had an obvious influence on the thermostability of Y. NSN. According to the analysis of enzyme activity and thermostability of Y. NSN, we found that Glu202, Ile203 and Asp264 might be the key residues for its high enzyme activity and good thermostability. Conclusions: Among all factors affecting enzyme activity and thermostability of Y. NSN, they failed to explain the experimental results well. One reason might be that the enzyme activity and thermostability of Y. NSN were affected not only by a single factor but also by the entire environment.

Activity of encapsulated Lactobacillus bulgaricus in alginate-whey protein microspheres

In this work, alginate-whey protein was used as wall materials for encapsulating Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus). The characteristics of encapsulated and free L. bulgaricus showed that the free L. bulgaricus lost viability after 1 min exposure to simulated gastric fluid (SGF) at pH 2.0 and 2.5. However, the viability of encapsulated L. bulgaricus did not decrease in SGF at pH 2.5 for 2 h incubation. The viable numbers of encapsulated L. bulgaricus decreased less than 1.0 log unit for 2 h incubation in SGF at pH 2.0. For bile stability, only 1.2 log units and 2.0 log units viability of the encapsulated L. bulgaricus was lost in 1 and 2% bile for 1 h exposure, respectively, compared with no survival of free L. bulgaricus under the same conditions. Encapsulated L. bulgaricus was completely released from the microspheres in simulated intestinal fluid (SIF, pH 6.8) in 3 h. The viability of the encapsulated L. bulgaricus retained more 8.0 log CFU/g after stored at 4°C for four weeks. However, for free L. bulgaricus, only around 3.0 log CFU/mL was found at the same storage conditions. Results showed that the encapsulation could improve the stability of L. bulgaricus.