Effect of sulfide on the nitrogen removal performance and microbial community of low-substrate Anammox process.

Anammox is one of the most innovative nitrogen removal technologies, while its functional bacteria-anaerobic ammonia-oxidizing bacteria (AAOB) is sensitive to the impurities in the wastewater. In this study, the long-term effects of sulfide at different concentrations (0, 5, 10, 20, 30, 50, 25 mg L-1) on low substrate Anammox process were studied. The results showed that when the sulfide was 25-30 mg L-1, AAOB was well coupled with sulfide-denitrifying bacteria and the total nitrogen removal efficiency (TNRE) reached a maximum of 91.0%. The hydroxylamine oxidoreductase activity and Heme-c reached 1.678 EU g-1 SS and 0.0023 mmol g-1 SS, respectively, with the hzo and nosZ gene concentrations as 2.52 × 108 and 4.45 × 107 copies mL-1. 50 mg L-1 sulfide inhibited the nitrogen removal by AAOB, resulting in the TNRE decreasing to 81.7%. The experimental results provide a reference for the practical application of Anammox in treating sulfur-containing wastewater.

Post-crotonylation oxidation by a monooxygenase promotes acetyl-CoA synthetase degradation in Streptomyces roseosporus.

Protein post-translational modifications (PTMs) with various acyl groups play central roles in Streptomyces. But whether these acyl groups can be further modified, and the influences of these potential modifications on bacterial physiology have not been addressed. Here in Streptomyces roseosporus with rich crotonylation, a luciferase monooxygenase LimB is identified to elaborately regulate the crotonylation level, morphological development and antibiotic production by oxidation on the crotonyl groups of an acetyl-CoA synthetase Acs. This chemical modification on crotonylation leads to Acs degradation via the protease ClpP1/2 pathway and lowered intracellular crotonyl-CoA pool. Thus, we show that acyl groups after PTMs can be further modified, herein named post-PTM modification (PPM), and LimB is a PTM modifier to control the substrate protein turnover for cell development of Streptomyces. These findings expand our understanding of the complexity of chemical modifications on proteins for physiological regulation, and also suggest that PPM would be widespread.

Determination of Pb, Cr, Cd, and As in Aluminum-Plastic Packaging Materials via Inductively Coupled Plasma-Mass Spectrometry with Microwave Digestion.

Microwave digestion was performed to study the pretreatment methods of aluminum-plastic packaging materials (APPMs). Five different digestion reagent combinations and proportions were thoroughly considered. Digestion results indicated that the most suitable reagent combination was sulfuric and nitric acids with the optimal proportion of 1∶7 after the orthogonal experiment. Moreover, the possible reasons of the experimental phenomenon were analyzed. The contents of Pb, Cr, Cd, and As in APPMs were subsequently determined via inductively coupled plasma-mass spectrometry (ICP-MS). The satisfactory linearity of calibration curves was obtained with the linear correlation coefficients above 0.999 5, and the instrument detection limits of Pb, Cr, Cd, and As for the current method were 0.215, 0.067, 0.006 and 0.020 ng·mL-1, respectively. Furthermore, the recoveries of standard addition ranged from 83.8% to 111.6%, and the relative standard deviations ranged from 0.5% to 7.4%. Two independent parallel determination results of Pb, Cr, Cd, and As in APPMs were approaching, and the student's t-test (confidence level, α=0.05) showed that the determination results had no significant differences. In conclusion, the present method exhibited fine linearity, low detection limit, high recovery, and good precision, which can accurately be utilized to analyze Pb, Cr, Cd, and As elements in APPMs or other similar materials.

[A prospective randomized control clinical trial about clopidogrel combined with warfarin versus clopidogrel alone in the prevention of restenosis after femoral-popliteal artery angioplasty].

OBJECTIVE: Using two antithrombotic treatment (clopidogrel vs. clopidogrel combined warfarin) strategies after femoral-popliteal artery angioplasty prospectively, to evaluate which strategy is more effective for the restenosis prevention. METHODS: Totally 50 patients referred for endovascular treatment (including the percutaneous transluminal angioplasty (PTA) and stent implantation) of the superficial femoral artery and popliteal artery from January 2008 to May 2009 were randomly divided into clopidogrel group (group A, 25 cases, 30 limbs) and clopidogrel plus warfarin group (group B, 25 cases, 33 limbs) before operation. Clinical outcomes and restenosis rate of the target lesions were evaluated at 3, 6 and 12 months after operation. RESULTS: Totally 88 patients were screened for participation in the study, 56 patients were included after the follow-up of 12 months. At 3 months, the rates of restenosis were 16.7% in group A and 18.2% in group B (χ² = 0.025, P = 0.874). At 6 months, the accumulated restenosis rates were 36.7% in group A and 36.4% in group B (χ² = 0.001, P = 0.98). At 12 months, the accumulated restenosis rates were 53.3% in group A and 42.4% in group B (χ² = 0.75, P = 0.387). Analysis for the critical limb ischemia sub-group showed that follow-up of 12 months, the accumulated restenosis rate was 8/10 in group A and 6/12 in group B (χ² = 1.023, P = 0.312). CONCLUSION: The clopidogrel alone treatment for PTA or PTA plus stent implantation of femoral popliteal artery has no statistically significant difference in comparison with the clopidogrel combined warfarin treatment in terms of the cumulative vascular restenosis rate at 3, 6, 12 months postoperatively.

Analysis of serum enzyme levels in a rabbit model of acute mesenteric ischemia.

Early diagnosis of acute mesenteric ischemia (AMI) remains very difficult, partly due to the fact that useful markers of early small bowel ischemia have not yet been identified. Thus, in this study, we aimed to evaluate the levels of serum intracellular enzymes in the tissues and organs in a controlled animal model of mesenteric intestinal ischemia. Forty-eight New Zealand rabbits were divided into 4 groups including the control, artery ligation, vein ligation, and both artery and vein ligation groups. Plasma samples were obtained at 0-, 1-, 3-, 6- and 9-h time-points and enzyme levels were determined. The bowel color and vitality were observed at the same time. The bowel showed an appearance of infarction after a period of ischemia in the animals. Six and 9 h after superior mesenteric artery ischemia, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels increased significantly. However, after 3 h of superior mesenteric venous (SMV) ligation, γ-glutamyl transpeptidase levels in the blood were considerably higher compared to the control group. Six hours after SMV ischemia, ALT, AST, alkaline phosphatase and lactate dehydrogenase levels were significantly elevated compared to those pre-ligation. Serum enzyme levels during intestinal ischemia are not able to provide sufficient information as regards the extent and reversibility of intestinal ischemia, although, they may be able to reflect the presence of injury.