No abstract

Phenethyl isothiocyanate (PEITC), a constituent of cruciferous vegetables, has been shown to inhibit chemical carcinogenesis, possibly due to its ability to block the activation or to enhance the detoxification of chemical carcinogens. The present study was conducted to elucidate the biochemical mechanisms involved by characterizing the effects of PEITC on phase I and phase II xenobiotic-metabolizing enzymes. A single dose of PEITC to F344 rats (1 mmol/kg) decreased the liver N-nitrosodimethylamine demethylase (NDMAd) activity (mainly due to P450 2E1) by 80% at 2 h and the activity of NDMAd remained decreased by 40% at 48 h after treatment. The liver pentoxyresorufin O-dealkylase (PROD) activity and P450 2B1 protein level were elevated 10- and 7-fold at 24 h after treatment respectively. The liver microsomal ethoxyresorufin O-dealkylase (EROD) (mainly due to P450 1A) and erythromycin N-demethylase (mainly due to P450 3A) activities were decreased at 2-12 h after treatment and recovered afterwards. The lung microsomal PROD and EROD activities were not significantly affected; whereas, the nasal microsomal PROD and EROD activities were decreased by 40-50%. After a treatment with PEITC, the rates of oxidative metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were decreased in liver microsomes by 40-60% at 2 h and recovered gradually; the rates in lung microsomes were markedly decreased by 60-70% at 2 h and remained at the decreased level at 24 h; and the rates in nasal mucosa microsomes were decreased gradually with the lowest activities observed at 18 h (50%) followed by a gradual recovery. Furthermore, the treatment with PEITC resulted in a maximal 5-fold increase of NAD(P)H:quinone oxidoreductase and 1.5-fold increase of glutathione S-transferase activities in the liver, but the activities of these two enzymes were not significantly affected in the lung and nasal mucosa. The sulfotransferase activity in the liver was decreased by 32-48% at 24-48 h after treatment; the nasal activity was increased by 1.8- to 2.5-fold, but the lung activity was not significantly changed. The hepatic UDP glucuronosyltransferase activity was slightly decreased at 2 h but slightly increased at 48 h after treatment, but no changes were observed for the lung and nasal activities. The study demonstrates that PEITC selectively affects xenobiotic-metabolizing enzymes in the liver, lung and nasal mucosa and it is especially effective in inhibiting the P450-dependent oxidation of NNK in the lung and of NDMA in the liver.

Aims:  To clone and characterize genes encoding novel cellulases from metagenomes of buffalo rumens. Methods and Results:  A ruminal metagenomic library was constructed and functionally screened for cellulase activities and 61 independent clones expressing cellulase activities were isolated. Subcloning and sequencing of 13 positive clones expressing endoglucanase and MUCase activities identified 14 cellulase genes. Two clones carried two gene clusters that may be involved in the degradation of polysaccharide nutrients. Thirteen recombinant cellulases were partially characterized. They showed diverse optimal pH from 4 to 7. Seven cellulases were most active under acidic conditions with optimal pH of 5·5 or lower. Furthermore, one novel cellulase gene, C67‐1, was overexpressed in Escherichia coli, and the purified recombinant enzyme showed optimal activity at pH 4·5 and stability in a broad pH range from pH 3·5 to 10·5. Its enzyme activity was stimulated by dl‐dithiothreitol. Conclusions:  The cellulases cloned in this work may play important roles in the degradation of celluloses in the variable and low pH environment in buffalo rumen. Significance and Impact of the Study:  This study provided evidence for the diversity and function of cellulases in the rumen. The cloned cellulases may at one point of time offer potential industrial applications.

Evidence exists for a specific diabetic cardiomyopathy independent of concurrent vascular disease. We tested the hypothesis that chronic hyperglycaemia found in streptozotocin- (STZ) induced diabetic rats leads to an altered response to and contractile effects of hyperosmotic shrinkage in ventricular myocytes. Analysis confirmed significant hyperglycaemia and revealed significant blood hyperosmolarity in STZ-treated rats. Myocyte volume changes, shortening and intracellular Ca(2+) ([Ca(2+)](i)) transients were measured in cells superfused with normal Tyrode (NT, 300 mmol/kg) and then hyperosmotic Tyrode (HT, 440 mmol/kg) at 35-36 degrees C. Shrinking significantly reduced the amplitude of shortening, whilst the [Ca(2+)](i) transient was significantly increased. The time course of both shortening and the [Ca(2+)](i) transient were prolonged in myocytes from STZ-treated compared to control rats. Time to peak shortening was 130.3 ms in STZ compared to 100.2 ms in control myocytes. Time to peak [Ca(2+)](i) transient was 70.8 ms in STZ compared to 44.6 ms in control myocytes and the time from peak to half recovery was 191.0 ms in STZ compared to 169.1 ms in control myocytes. Fractional SR Ca(2+) release, assessed by the application of caffeine, was increased by shrinking. However, the effects of raised extracellular osmolarity on volume changes, contractility and [Ca(2+)](i) were not altered by the chronic hyperglycaemia found in STZ-treated rats.

In this paper, a facilely prepared electrochemiluminescence (ECL) biosensor was developed for Escherichia coli O157:H7 quantitative detection based on a polydopamine (PDA) surface imprinted polymer (SIP) and nitrogen-doped graphene quantum dots (N-GQDs). N-GQDs with a high quantum yield of 43.2% were synthesized. The uniform PDA SIP film for E. coli O157:H7 was established successfully with a facile route. The dopamine and target bacteria were electropolymerized directly on the electrode. After removal of the E. coli O157:H7 template, the established PDA SIP can selectively recognize E. coli O157:H7. Accordingly, E. coli O157:H7 polyclonal antibody (pAb) was labeled with N-GQDs. The bioconjugation of SIP-E. coli O157:H7/pAb-N-GQDs can generate intensive ECL irradiation with KSO. As a result, E. coli O157:H7 was detected with the ECL sensing system. Under optimal conditions, the linear relationships between the ECL intensity and E. coli O157:H7 concentration were obtained from 10 colony-forming units (CFU) mL to 10 CFU mL with a limit of detection of 8 CFU mL. The biosensor based on this SIP film was applied in water sample detection successfully. The N-GQD-based ECL analytical method for E. coli O157:H7 was reported for the first time. The sensing system had high selectivity to the target analyte, provided new opportunities for use, and increased the rate of disease diagnosis and treatment and the prevention of pathogens.

No abstract

No abstract

Background: Cellulose is the most abundant biomass on earth. The major players in cellulose degradation in nature are cellulases produced by microorganisms. Aerobic filamentous fungi are the main sources of commercial cellulase. Trichoderma reesei has been explored extensively for cellulase production; however, its major limitations are its low β-glucosidase activity and inefficiency in biomass degradation. The aim of this work was to isolate new fungal strains from subtropical and tropical forests in China, which produce high levels of cellulase in order to facilitate development of improved commercial cellulases.