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A mediated glassy carbon electrode covered by a thin-film polyviologen was used in the present study to rapidly detect bioactivity in a mixed-culture chemostat (dominated by Clostridium sp.). With the addition of 1mM hexacyanoferrate and 9mM glucose, the current increasing rate (dI/dt) measured under a poised potential of 500mV (vs. Ag/AgCl) can be defined as the quantity of metabolic activity. In the experiment of restoring the chemostat from stop-feeding, it is suggested that when the dI/dt was >2μAmin-1, the influent pump could be directly turned on to maintain the high dilution rate of 0.5h-1; when the dI/dt was lower than 2μAmin-1, reducing the dilution rate would be needed to avoid cell wash out. Since the soluble mediators and polyviologen film will enhance performances by favorable electron transfer and positively charged surfaces, respectively, we suggest that the method can also be employed to detect the bioactivities in environmental samples.

This study evaluated anaerobic hydrogenation performance and microbial ecology in bioreactors operated at different hydraulic retention time (HRT) conditions and fed with glucose–peptone (GP) and starch–peptone (SP). The maximum hydrogen production rates for GP- and SP-fed bioreactors were found to be 1247 and 412 mmol-H 2 /L/d at HRT of 2 and 3 h, respectively. At HRT > 8 h, hydrogen consumption due to peptone fermentation could occur and thus reduced hydrogen yield from carbohydrate fermentation. Results of cloning/sequencing and denaturant gradient gel electrophoresis (DGGE) indicated that Clostridium sporogenes and Clostridium celerecrescens were dominant hydrogen-producing bacteria in the GP-fed bioreactor, presumably due to their capability on protein hydrolysis. In the SP-fed bioreactor, Lactobacillus plantarum , Propionispira arboris , and Clostridium butyricum were found to be dominant populations, but the presence of P. arboris at HRT > 3 h might be responsible for a lower hydrogen yield from starch fermentation. As a result, optimizing HRT operation for bioreactors was considered an important asset in order to minimize hydrogen-consuming activities and thus maximize net hydrogen production. The limitation of simple parameters such as butyrate to acetate ratio (B/A ratio) in predicting hydrogen production was recognized in this study for bioreactors fed with multiple substrates. It is suggested that microbial ecology analysis, in addition to chemical analysis, should be performed when complex substrates and mixed cultures are used in hydrogen-producing bioreactors.

The biochemical hydrogen potential (BHP) tests were conducted to investigate the metabolism of glucose fermentation and hydrogen production performance of four Clostridial species, including C. acetobutylicum M121, C. butyricum ATCC19398, C. tyrobutyricum FYa102, and C. beijerinckii L9. Batch experiments showed that all the tested strains fermented glucose, reduced medium pH from 7.2 to a value between 4.6 and 5.0, and produced butyrate (0.37–0.67 mmol/mmol-glucose) and acetate (0.34–0.42 mmol/mmol-glucose) as primary soluble metabolites. Meanwhile, a significant amount of hydrogen gas was produced accompanied with glucose degradation and acid production. Among the strains examined, C. beijerinckii L9 had the highest hydrogen production yield of 2.81 mmol/mmol-glucose. A kinetic model was developed to evaluate the metabolism of glucose fermentation of those Clostridium species in the batch cultures. The model, in general, was able to accurately describe the profile of glucose degradation as well as production of biomass, butyrate, acetate, ethanol, and hydrogen observed in the batch tests. In the glucose re-feeding experiments, the C. tyrobutyricum FYa102 and C. beijerinckii L9 isolates fermented additional glucose during re-feeding tests, producing a substantial amount of hydrogen. In contrast, C. butyricum ATCC19398 was unable to produce more hydrogen despite additional supply of glucose, presumably due to the metabolic shift from acetate/butyrate to lactate/ethanol production.

To monitor the bioactivity change of a hydrogen fermentor, this work presents a novel bioelectrochemical method equipped with a polyviologen modified glassy carbon as a working electrode and with ferricyanide as an electron mediator. Experimental results demonstrated that the ferricyanide can transfer electrons from hydrogen producing bacteria cells to electrode without significant inhibition on cell growth. To protect the electrode from fouling by protein and bacteria during bioassay, polyviologen film was applied to modify the working electrode, and stabilized the responding current compared to the use of bare electrode. The amperometric bioassay provided the bioactivity information for indicating the statue of the fermentor and helping draw up the operation strategy when the fermentor was operated under abnormal conditions, including stop-feeding and re-feeding. The results of bioactivity monitoring suggested an interesting phenomenon that the activity of hydrogen producing bacteria transiently increased during the unsteady period and then decreased.

We have investigated pressure-enhanced C−H···O interactions in tert-butyl alcohol (TBA)/D2O mixtures. On the basis of its responses to changes in pressure and concentration, TBA appears to be the ideal candidate to study the variations in structural and dynamical properties of C−H···O interactions. For dilute aqueous TBA, the pressure dependence of the C−H bands yielded blue frequency shifts at pressures below 0.3 GPa, but an increase in pressure leads to a red frequency shift at pressures above this value. This discontinuity in frequency shift is related to enhanced C−H···O interactions. The frequency of the C−H stretching modes that characterize C−H···O hydrogen bonding undergoes a blue shift with pressure. This behavior is in contrast with the general trend of red shifts observed in strongly hydrogen-bonded systems that occur through O−H···O and CO···H interactions. We discuss the results of density functional theory calculations that predict the frequency shift of the C−H stretching vibrations.

Objective Renal cell carcinoma (RCC) is the most lethal genitourinary cancer and intrinsically resistant to chemotherapy, radiotherapy, and hormone therapy. Annexin A2 (Anxa2) is a calcium-dependent phospholipid-binding protein found on various cell types that plays multiple roles in regulating cellular functions. In RCC, Anxa2 expression was correlated with tumor differentiation, clinical outcomes, and the metastatic potential; however, the underlying mechanisms remain obscure. This study investigated the role of Anxa2 in regulating tumorigenesis of RCC. Materials and methods Commercial RCC tissue microarray arrays and a kidney cancer quantitative polymerase chain reaction array were used to examine Anxa2 by immunohistochemistry and real-time polymerase chain reaction analysis. Short hairpin (sh)RNA–based lentiviral system technology was used to evaluate the effects of manipulating Anxa2 expression on multiple malignant features of 2 RCC cell lines, A498 and 786-O, and its mechanisms. Results (1) The Anxa2 expression level was generally elevated to varying degrees in RCC tissues. In adjacent noncancerous tissues, Anxa2 was mainly expressed in glomeruli and slightly expressed in the cytoplasm of proximal tubules. (2) An increased Anxa2 expression level was found in tissues of clear cell RCC, papillary RCC, and chromophobe RCC, and it was prominently expressed in cancer cell membranes. In addition, the Anxa2 expression level was correlated with poor prognosis. (3) Silencing Anxa2 expression suppressed the abilities of cell migration and invasion, but cell proliferation was less affected. (4) Diminished Anxa2 expression caused alterations in the cell polarity, disrupted the formation of actin filaments, and reduced CXCR4 expression. (5) Inhibition of the Rho/Rock axis restored silencing of Anxa2-mediated suppression of cell motility. Conclusions Overall, our study points out the regulatory function of Anxa2 in RCC cell motility and provides a molecular-based mechanism of Anxa2 positivity in the progression of RCC.

Objective Glucose-regulated protein 78 (Grp78) is an endoplasmic reticulum chaperone; it maintains endoplasmic reticulum homeostasis and modulates unfolded protein response. The protein is overexpressed in various cancer types, including renal cell carcinoma (RCC). Increased Grp78 expression in patients with RCC is correlated with more aggressive tumors and poorer prognoses. This study investigated the role of Grp78 in regulating tumorigenesis and evaluated the potential of Grp78-targeted therapy for RCC. Methods The expression level of Grp78 was examined in von Hippel-Lindau (VHL)-intact or VHL-null RCC cell lines by reverse transcription polymerase chain reaction and Western blot. Specific Grp78 ribonucleic acid interference was applied as a molecularly Grp78-targeted therapeutic approach. This method enabled us to assess the effects of manipulating Grp78 expression to regulate RCC cell growth. Results The Grp78 messenger ribonucleic acid and protein were expressed in both VHL-intact and VHL-null RCC cell lines. The specific inhibition of Grp78 expression suppressed RCC cell growth and colony formation significantly, and induced G1 cell-cycle arrest. We also showed that inhibiting Grp78 expression increased the cells' resistance to the cytotoxicity of the S-phase-specific anticancer drug 5-fluorouracil. This effect was regulated by the unfolded protein response-induced suppression of G1/S transition-related cyclins (D1, E1, and E2) and cyclin-dependent kinase (CDK4 and CDK6) protein expression. Conclusion Overall, our findings indicate the regulatory function of Grp78 in RCC cell proliferation, and provide a molecular-based mechanism of Grp78 positivity in the progression of RCC.

Biological hydrogen production from anaerobic waste fermentation possesses potential benefits in simultaneously reducing organic wastes and generating sustainable energy sources. Three kinetic-based steady-state models for anaerobic fermentation of multiple substrates, including glucose and peptone, were evaluated. Experimental results obtained from a continuous stirred tank reactor (CSTR) were primarily used for model evaluation. The dual-substrate steady-state model developed and the associated kinetic parameters estimated in this study successfully described the anaerobic growth of hydrogen-producing bacteria. The model was able to capture the general trends of consumption of substrates and accumulation of products, including formate, acetate, butyrate, and hydrogen, at dilution rates (D) between 0.06 and 0.69/h. According to the model, the adverse effects of endogeneous and peptone metabolism on net hydrogen production can be minimized by increasing D. For the operational conditions of D > 0.69/h, however, substantial washout of hydrogen-producing bacteria from the CSTR was observed, and it resulted in a rapid drop in hydrogen production rate as well. © 2006 Wiley Periodicals, Inc.

We have probed under high pressure the C-H hydrogen bonds formed by N,N(')-disubstituted imidazolium ions having PF(6) (-) and Br(-) counterions. High-pressure infrared spectral profiles, x-ray crystallographic analysis, and ab initio calculations allow us to make a vibrational assignment of these compounds. The appearance of a signal for the free-NH unit (or weakly bonded N-H...F unit) in the infrared spectrum of the PF(6) (-) salt indicates that conventional N-H...O and N-H...N hydrogen bonds do not fully dominate the packing. It is likely that the charge-enhanced C(2)-H...F interactions, combined with other weak hydrogen bonds, disturb the formation of N-H hydrogen bonds in the PF(6) (-) salt. This finding is consistent with the pressure-dependent results, which reveal that the C(2)-H...F interaction is enhanced upon increasing the pressure. In contrast to the PF(6) (-) salt, the imidazolium C-H bonds of the Br(-) salt have low sensitivity to high pressure. This finding suggests that the hydrogen bonding patterns are determined by the relative hydrogen bond acceptor strengths of the Br(-) and PF(6) (-) ions.