Reactive oxygen species in phagocytic leukocytes

Phagocytic leukocytes consume oxygen and generate reactive oxygen species in response to appropriate stimuli. The phagocyte NADPH oxidase, a multiprotein complex, existing in the dissociated state in resting cells becomes assembled into the functional oxidase complex upon stimulation and then generates superoxide anions. Biochemical aspects of the NADPH oxidase are briefly discussed in this review; however, the major focus relates to the contributions of various modes of microscopy to our understanding of the NADPH oxidase and the cell biology of phagocytic leukocytes

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202112 bcvcNot applicableOthersThe first author was supported in part by The Hong Kong Polytechnic University under a grant number ZVK9.Published24 month

A novel and effective hepatocyte growth factor kringle 1 domain and p53 cocktail viral gene therapy for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide, yet effective therapeutic options for advanced HCC are limited. Kringle 1 domain of HGF (HGFK1) has been demonstrated as a potent anti-tumor molecule and p53 is a well established tumor suppressor. Recently we developed AAV transducing HGFK1 (AAV-HGFK1) as a gene therapy for HCC. Here we investigated the possibility of enhancing the effect of AAV-HGFK1 by combining it with Adv transducing p53 (Adv-p53). In vitro expression experiments suggested a small amount of Adv-p53 could increase the expression of AAV transgenes. AAV-HGFK1 + Adv-p53 cocktail strongly inhibited the proliferation of microvascular endothelial cell (MEC) and two HCC cell lines, Hepa1-6 and McA-RH7777. In two orthotopic mice and rat HCC models the cocktail gene therapy also significantly reduced the tumor burdens and prolonged the survival time by inhibiting tumor angiogenesis and inducing tumor cell death. Significantly, tumor metastasis was completely prevented. AAV-HGFK1 + Adv-p53 viral cocktail may be a promising cancer therapy for the treatment of HCC. © 2008 Elsevier Ireland Ltd. All rights reserved.link_to_subscribed_fulltex

Selective enrichment and production of highly urease active bacteria by non-sterile (open) chemostat culture

In general, bioprocesses can be subdivided into naturally occurring processes, not requiring sterility (e.g., beer brewing, wine making, lactic acid fermentation, or biogas digestion) and other processes (e.g., the production of enzymes and antibiotics) that typically require a high level of sterility to avoid contaminant microbes overgrowing the production strain. The current paper describes the sustainable, non-sterile production of an industrial enzyme using activated sludge as inoculum. By using selective conditions (high pH, high ammonia concentration, and presence of urea) for the target bacterium, highly active ureolytic bacteria, physiologically resembling Sporosarcina pasteurii were reproducibly enriched and then continuously produced via chemostat operation of the bioreactor. When using a pH of 10 and about 0.2 M urea in a yeast extract-based medium, ureolytic bacteria developed under aerobic chemostat operation at hydraulic retention times of about 10 h with urease levels of about 60 μmol min-1 ml-1 culture. For cost minimization at an industrial scale the costly protein-rich yeast extract medium could be replaced by commercial milk powder or by lysed activated sludge. Glutamate, molasses, or glucose-based media did not result in the enrichment of ureolytic bacteria by the chemostat. The concentration of intracellular urease was sufficiently high such that the produced raw effluent from the reactor could be used directly for biocementation in the field

Stress response in tardigrades: differential gene expression of molecular chaperones

Semi-terrestrial tardigrades exhibit a remarkable tolerance to desiccation by entering a state called anhydrobiosis. In this state, they show a strong resistance against several kinds of physical extremes. Because of the probable importance of stress proteins during the phases of dehydration and rehydration, the relative abundance of transcripts coding for two α-crystallin heat-shock proteins (Mt-sHsp17.2 and Mt-sHsp19.5), as well for the heat-shock proteins Mt-sHsp10, Mt-Hsp60, Mt-Hsp70 and Mt-Hsp90, were analysed in active and anhydrobiotic tardigrades of the species Milnesium tardigradum. They were also analysed in the transitional stage (I) of dehydration, the transitional stage (II) of rehydration and in heat-shocked specimens. A variable pattern of expression was detected, with most candidates being downregulated. Gene transcripts of one Mt-hsp70 isoform in the transitional stage I and Mt-hsp90 in the anhydrobiotic stage were significantly upregulated. A high gene expression (778.6-fold) was found for the small α-crystallin heat-shock protein gene Mt-sHsp17.2 after heat shock. We discuss the limited role of the stress-gene expression in the transitional stages between the active and anhydrobiotic tardigrades and other mechanisms which allow tardigrades to survive desiccation