Theoretical Study on the Mechanism of the Acylate Reaction of ß-Lactamase.

Using density functional theory and a cluster approach, we study the reaction potential surface and compute Gibbs free energies for the acylate reaction of ß-lactamase with penicillin G, where the solvent effect is important and taken into consideration. Two reaction paths are investigated: one is a multi-step process with a rate-limit energy barrier of 19.1 kcal/mol, which is relatively small, and the reaction can easily occur; the other is a one-step process with a barrier of 45.0 kcal/mol, which is large and thus makes the reaction hard to occur. The reason why the two paths have different barriers is explained.

Urotensin-â ¡Receptor Antagonist SB-710411 Protects Rat Heart against Ischemia-Reperfusion Injury via RhoA/ROCK Pathway.

AIM: SB-710411 is a rat selective urotensin-II (U-II) receptor antagonist, which can block U-II-induced contraction of the aorta and inhibit U-II-induced myocardial fibrosis in rats. However, the effect of SB-710411 on myocardial ischemia-reperfusion (I/R) injury is unclear. The present study was designed to investigate whether SB-710411 has a protective effect on myocardial I/R injury in rats and the possible mechanisms. METHODS AND RESULTS: Myocardial I/R injury was induced by occluding the left anterior descending coronary artery in adult male Sprague-Dawley rats. Hemodynamic parameters, electrocardiogram (ECG), infarct size, histological alteration, lactate dehydrogenase (LDH), creatine phosphokinase-MB (CK-MB), cardiac troponin I (cTnI), RhoA, and the protein expressions of U-II receptor (UTR), ROCK1 and ROCK2 were evaluated. Cardiac I/R injury significantly up-regulated the expressions of UTR, ROCK1 and ROCK2 proteins in rat myocardium. SB-710411 1.0 and 2.0 µg/kg significantly reduced cardiac I/R-induced the infarct size and histological damage in rat myocardium, markedly inhibited the changes of hemodynamic parameters and the increases of ST-segment in ECG, the serum LDH and CK-MB activities and cTnI level in rats subjected to myocardial I/R injury. Furthermore, SB-710411 obviously prevented myocardial I/R-increased RhoA activity and UTR, ROCK1 and ROCK2 protein expressions. CONCLUSIONS: Our results indicate that cardiac I/R injury increases myocardial UTR expression, and SB-710411 has a potent protective effect on myocardial I/R injury in rats. The cardioprotection may be associated with the inhibition of UTR-RhoA/ROCK pathway.

[Human mesenchymal stem cells modified by hepatocyte growth factor gene promote chicken embryonic angiogenesis].

This study was purposed to investigate the angiogenesis-promoting activities of human mesenchymal stem cells (hMSCs) modified by hepatocyte growth factor (HGF) and the underlying mechanisms. The hMSCs were transfected by recombinant adenoviral vector carrying human HGF gene and seeded onto the chicken chorioallantoic membrane. Three days later, the number of blood vessels was counted and their angiogenic response was compared with those of hMSCs of same generation, recombinant basic fibroblast growth factor (bFGF) and alpha-MEM as control. The expression levels of bFGF, VEGF, angiopoietin-1 and angiopoietin-2 were evaluated by RT-PCR assay. The results showed that gene-modified hMSCs exhibited greatest activity to promote angiogenesis while the angiogenic response was nearly same between groups treated by hMSCs and bFGF, all of which were significantly higher than that observed in control (p < 0.01). RT-PCR analysis revealed that hMSCs constitutively expressed multiple angiogenesis-associated growth factors and their levels seemed up-regulated by HGF gene transfer. It is concluded that HGF gene-modified hMSCs show a potent angiogenesis-promoting function and may be useful in the treatment of ischemic disorders.

Combination effect of oncolytic adenovirus therapy and herpes simplex virus thymidine kinase/ganciclovir in hepatic carcinoma animal models.

AIM: Oncolytic adenovirus, also called conditionally replicating adenovirus (CRAD), can selectively propagate in tumor cells and cause cell lysis. The released viral progeny can infect neighboring cancer cells, initiating a cascade that can lead to the ultimate destruction of the tumor. Suicide gene therapy using herpes simplex virus thymidine kinase (HSV-TK) and ganciclovir (GCV) offers a potential treatment strategy for cancer and is undergoing preclinical trials for a variety of tumors. We hypothesized that HSV-TK gene therapy combined with oncolytic adenoviral therapy would have an enhanced effect compared with the individual effects of the therapies and is a potential novel therapeutic strategy to treat liver cancer. METHODS: To address our hypothesis, a novel CRAD was created, which consisted of a telomerase-dependent oncolytic adenovirus engineered to express E1A and HSV-TK genes (Ad-ETK). The combined effect of Ad-ETK and GCV was assessed both in vitro and in vivo in nude mice bearing HepG2 cell-derived tumors. Expression of the therapeutic genes by the transduced tumor cells was analyzed by RT-PCR and Western blotting. RESULTS: We confirmed that Ad-ETK had antitumorigenic effects on human hepatocellular carcinoma (HCC) both in vitro and in vivo, and the TK/GCV system enhanced oncolytic adenoviral therapy. We confirmed that both E1A and HSV-TK genes were expressed in vivo. CONCLUSION: The Ad-ETK construct should provide a relatively safe and selective approach to killing cancer cells and should be investigated as an adjuvant therapy for hepatocellular carcinoma.

[Dynamic changes of enzymes activities and growth factors contents in human colostrum].

OBJECTIVE: To study the dynamic changes of the activities of superoxide dismutase (SOD), amylase (AM) and alkaline phosphatase (ALP) and of the contents of epithelium growth factors (EGF) and insulin growth factors (IGF-1) in human colostrum (lactation 1 - 7 days postpartum). METHODS: A total of 118 samples of human colostrum were taken from 20 healthy women postpartum. The activities of SOD, AM and ALP in human colostrum were determined by methods of pyrogallol autoxidation, colorimetry of iodine-starch and pyrocatechol phosphate respectively. EGF and IGF-1 contents in human colostrum were measured by radioimmunoassay. RESULTS: The SOD activity of human colostrum increased slightly during lactation 1 - 4 days postpartum, from (18.7 +/- 2.2) kU/L to (22.5 +/- 2.9) kU/L, then it tended to decrease, being (11.2 +/- 2.1) kU/L on the 7th day. The SOD activities in lactation 1 - 5 days postpartum were significantly higher than that on day 7 (P < 0.05 or P < 0.01). AM and ALP activities of human colostrum gradually decreased within a week postpartum. AM activity declined from (155 +/- 12) kU/L to (17 +/- 4) kU/L. ALP activity declined from (105 +/- 17) kU/L to (54 +/- 9) kU/L. AM activities in lactation 1 - 5 days postpartum were significantly higher than that on day 7 (P < 0.05 or P < 0.01); and ALP activity on the first lactation day was significantly higher than that on day 7 (P < 0.05). EGF and IGF-1 concentrations in human colostrum quickly declined during lactation 1 - 4 days postpartum. EGF concentration decreased from (105 +/- 11) micro g/L to (40 +/- 5) micro g/L, and IGF-1 concentration decreased from (25.9 +/- 2.7) micro g/L to (5.6 +/- 1.3) micro g/L. Both concentrations altered slightly during lactation 4 - 7 days postpartum. EGF concentrations in lactation 1 - 3 days postpartum were remarkably higher than that on day 7 (P < 0.05 or P < 0.01); IGF-1 concentration on the first lactation day was significantly higher than that on day 7 (P < 0.01). CONCLUSIONS: Human colostrum contains SOD, AM and ALP with high activities, and is also rich in EGF and IGF-1. All of these are indispensable to normal growth and development of infants. Breast-feeding should be emphasized and encouraged for infants.