Glutamine supported early enteral therapy for severe acute pancreatitis: A systematic review and meta-analysis.

BACKGROUND AND OBJECTIVES: Several studies have shown that glutamine (Gln) may play an important role in energy metabolism, inflammatory reactions, and immune processes in patients with severe acute pancreatitis (SAP). Nevertheless, the results of individual randomized controlled trials (RCTs) on Gln nutrition support for SAP are contradictory. This systematic review and meta-analysis evaluated the clinical benefit of Gln-supported early enteral nutrition (G+EEN) in patients with SAP. METHODS AND STUDY DESIGN: Cochrane Library, PubMed, Embase, CNKI, Wan Fang, and Chinese Biomedical Literature Database were searched for relevant studies published before December 2018. RCTs of G+EEN versus standard early enteral nutrition (EEN) for SAP were selected, with both started within 48 h of admission. RESULTS: Seven clinical RCTs including a total of 433 patients (EEN group: 218 patients; G+EEN group: 215 patients) were included. Compared with EEN, G+EEN increased serum albumin (standard mean difference [SMD]=0.74; 95% confidence interval [CI], 0.33-1.15; p<0.01), reduced serum hypersensitive C-reactive protein (SMD=-1.62; 95% CI, -1.98 to -1.26; p<0.01) and risks of mortality risk (risk ratio= 0.38; 95% CI, 0.16-0.90; p=0.03) and multiple organ dysfunction syndrome (MODS)(risk ratio=0.37; 95% CI, 0.15-0.94; p<0.01), and shortened length of hospital stay (SMD=-1.19; 95% CI, -1.88 to 0.49; p<0.01); moreover, it did not significantly increase the incidence of infection-related complications, operative interventions, or APACHE II scores. CONCLUSIONS: G+EEN is beneficial in SAP management.

[Nitrogen Removal Effect and Conversion Characteristics of Nitrous Oxide in Single-stage and Multi-stage A/O Processes].

The single-stage A/O and multi-stage A/O processes were simulated by sequencing batch reactors (SBRs) with alternate stirring and aeration. The removal efficiency of nitrogen and the release mechanism of N2O were studied under the identical conditions of influent quality, hydraulic retention time (HRT), sludge retention time(SRT), temperature and anoxic/oxic (A/O) retention time ratio. Experimental results showed that COD or ammonia-nitrogen removal had no significant difference between the single-stage and the multi-stage A/O processes for the influent quality equivalent to municipal wastewater. However, TN removal efficiency of the former was better than the later with 72.1% and 52.2%, respectively. In the conversion of total nitrogen, during the typical cycle in the single-stage A/O and multi-stage A/O processes, the yields of N2O were 16.95 mg and 3.95 mg, respectively. The conversion rate, which is the ratio of N2O yield and TN removal, was respectively 11.47% and 4.11%. N2O production and emission occurred mainly in aerobic (nitrification) phase while there was little N2O emission in anoxic (denitrification) phase. Although the dominant species of AOB was both Nitrosomonas in the single-stage A/O and the multi-stage A/O processes under the same operating conditions, it was more conducive to the growth of nitrifying bacteria (AOB, NOB) in the single-stage A/O process with the greater abundance of Nitrosomonas. Meanwhile, the type and abundance of NOB in the single-stage A/O process were significantly more than in the multi-stage A/O process too. Therefore, it is more competitive to deal with the high-strengthening ammonia-nitrogen wastewater in the single-stage A/O process. In the actual operation of wastewater treatment, using appropriate partitions of A/O or oxygen-supplying modes can not only result in better nitrogen removal but also decrease the secondary pollution caused by N2O to the atmosphere.

Nutrient release, recovery and removal from waste sludge of a biological nutrient removal system.

The uncontrolled release of nutrients from waste sludge results in nitrogen and phosphorus overloading in wastewater treatment plants when supernatant is returned to the inlet. A controlled release, recovery and removal of nutrient from the waste sludge of a Biological Nutrient Removal system (BNR) are investigated. Results showed that the supernatant was of high mineral salt, high electrical conductivity and poor biodegradability, in addition to high nitrogen and phosphorus concentrations after the waste sludge was hydrolysed through sodium dodecyl sulphate addition. Subsequently, over 91.8% of phosphorus and 10.5% of nitrogen in the supernatants were extracted by the crystallization method under the conditions of 9.5 pH and 400 rpm. The precipitate was mainly struvite according to X-ray diffraction and morphological examination. A multistage anoxic-oxic Moving Bed Biofilm Reactor (MBBR) was then adopted to remove the residual carbon, nitrogen and phosphorus in the supernatant. The MBBR exhibited good performance in simultaneously removing carbon, nitrogen and phosphorus under a short aeration time, which accounted for 31.25% of a cycle. Fluorescence in situ hybridization analysis demonstrated that nitrifiers presented mainly in floc, although higher extracellular polymeric substance content, especially DNA, appeared in the biofilm. Thus, a combination of hydrolysis and precipitation, followed by the MBBR, can complete the nutrient release from the waste sludge of a BNR system, recovers nutrients from the hydrolysed liquor and removes nutrients from leftovers effectively.

A new classification paradigm of extracellular polymeric substances (EPS) in activated sludge: separation and characterization of exopolymers between floc level and microcolony level.

Extracellular polymeric substances (EPS) play a crucial role in the formation of activated sludge flocs. However, until now, the EPS are rather classified by the method used for extraction than by a theoretical consideration of their function and composition. In this paper, a new classification paradigm of EPS was proposed, which offered a novel approach to identify the role of EPS in the formation of activated sludge flocs. The current study gave an exploration to distinguish the EPS in the floc level (extra-microcolony polymers, EMPS) and in the microcolony level (extra-cellular polymers, ECPS). It was found that cation exchange resin treatment is efficient to disintegrate the flocs for EMPS extraction, however, inefficient to disaggregate the microcolonies for ECPS harvesting. A two-steps extraction strategy (cation exchange resin treatment followed by ultrasonication-high speed centrifugation treatment) was suggested to separate these two types of EPS in activated sludge flocs and the physicochemical characteristics of EMPS and ECPS were compared. The protein/polysaccharide ratio of ECPS was higher than that of EMPS and the molecular weight of proteins in EMPS and ECPS were found to be different. The ECPS contained higher molecular weight proteins and more hydrophobic substances than the EMPS contained. The result of excitation-emission matrix fluorescence spectroscopy analysis also showed that the EMPS and the ECPS have different fluorescent expressions and the components of EMPS were more diverse than that of ECPS. All results reported herein demonstrated that two different types of exopolymers exist in the activated sludge flocs and the inter-particle forces for aggregation of activated sludge flocs are not identical between the floc level and the microcolony level. It suggested that cation bridging interactions are more crucial in floc level flocculation, while the entanglement and hydrophobic interactions are more important in microcolony level cohesion.

The important implications of particulate substrate in determining the physicochemical characteristics of extracellular polymeric substances (EPS) in activated sludge.

Since the notable amount of particulate substrate in wastewater, the implications of particulate substrate on treatment efficiency have been a topic of major interest in the field of biological wastewater treatment. The particulate substrate has to be hydrolyzed by the extracellular enzymes, which are mainly embedded in extracellular polymeric substances (EPS) matrix of microbial aggregates, prior to consumption. Therefore, the important relevance between the particulate substrate and the characteristics of EPS can be expected. In this study, two lab-scale sequencing batch reactors were performed in parallel to investigate the effects of particulate and soluble substrate on the physicochemical characteristics of EPS in activated sludge. The results showed that the particulate substrate in the influent could significantly change the properties of activated sludge and the characteristics of EPS. More open and fluffy flocs with poorer settleability and dewaterability were formed with particulate substrate. More protein and humic compounds were introduced into the EPS matrix due to the deep involvement of protein and humic compounds in hydrolysis process of particulate substrate. The increments of protein and humic compounds then caused the slight higher molecular weight, higher hydrophobicity and lower zeta potential of EPS in particulate substrate system. The results in this study permitted for obtaining answers to understand the significant implications of particulate substrate in determining the physicochemical characteristics of EPS in biological wastewater treatment systems.

Hydrogen utilization rate: A crucial indicator for anaerobic digestion process evaluation and monitoring.

Hydrogenotrophic methanogens had been considered as key species for the anaerobic digestion (AD) of industrial wastewater and municipal sludge. However, how to evaluate the activity of the hydrogenotrophic methanogens was less studied. In this study, a volumetric device and a test procedure were developed for measuring the specific hydrogen utilization rate (HUR) of anaerobic sludge. Results showed that HUR values were highly influenced by sludge concentrations because of limitation on H2 mass transfer. The critical value of sludge concentration in the test bottle should not be higher than 1 gVSS/L. Under such condition, the kinetics of HUR would not be limited by H2 mass transfer and the maximal value of HUR could be obtained. Field survey confirmed that HUR exhibits a good relationship with specific methanogenic activity (SMA) and reactor performance. An anaerobic system with a relatively high HUR was found to be beneficial for maintaining H2 partial pressure in an appropriately low level. Moreover, such system was thermodynamically favourable for the syntrophic degradation of volatile fatty acids. As a crucial parameter of the anaerobic process, HUR could be used as a key indicator for evaluating and monitoring AD processes.

Investigation of the influencing factors on severe acute respiratory syndrome among health care workers.

OBJECTIVE: To investigate the protective factors and risk factors of nosocomial infection of severe acute respiratory syndrome (SARS) among health care workers (HCWs), and thus provide the scientific basis for prevention and control of nosocomial infection. METHODS: With the case-control study, a standardized questionnaire was used for data collection in three general hospitals where nosocomial infection had occurred. Univariate analysis was done at first. All concerned factors about SARS infection were scanned by using Chi-square test and Fisher's exact test one by one, and determined as to whether they were risk factors or protective factors according to odd ratio (OR) score. Then, multivariate unconditional logistic regression analysis was used to re-analyze the picked-out factors for finding out which factors played independent roles. RESULTS: Twenty-two factors (nineteen protective factors and three risk factors), among the total fifty-six factors, were significantly associated with SARS infection. Multivariate unconditional logistic regression revealed that factors such as double exposure suits (OR=0.053), education (OR=0.072), gloves (OR=0.102), hands sterilized by iodine (OR=0.231), room air ventilation (OR=0.32), were significantly protective; conversely, tracheal intubation (OR=30.793) was a significant risk factor. CONCLUSION: Strict defense and antisepsis measures were pivotal in preventing SARS infection among high-risk medical personnel. Education about associated knowledge and effective air ventilation were also important factors.

[Comparison of severe acute respiratory syndrome with community-acquired pneumonia].

OBJECTIVE: To study the features of severe acute respiratory syndrome (SARS) and community acquired pneumonia (CAP). METHODS: The clinical presentation, chest radiographs, white blood cell count and outcome of 45 SARS patients from April 5 to 20 2003 were compared, with those of 80 CAP patients from October 1 2002 to April 1 2003 in our hospital, and the clinical features of SARS were summarized. RESULTS: (1) Fever above 38.5 centigrade, dry cough, short of breath, headache, myalgia, diarrhea in SARS were more common in SARS patients than those in CAP (P<0.01). (2) Leucopenia was more common and leukocytosis was less common in SARS than those in CAP (P<0.01). (3) 22.2 percent of SARS patients were found abnormal chest radiographs within 24 hours after onset, 71.1 percent of SARS patients were showed progressive pulmonary infiltration via serial chest radiographs, while all CAP patients had abnormal chest radiographs when they were seen first time, and no patient showed progressive pulmonary infiltration, the difference was significant between the two groups (P<0.01). (4) Patients with SARS were lack of a response to the initial antimicrobial therapy, all patients with CAP had an adequate clinical response within three days, the difference was significant between the two groups(P<0.01 ). (5) The ratio of severe pneumonia and mortality in SARS was much higher than in CAP (both P<0.01). CONCLUSION: The clinical presentation, chest radiographs, white blood cell count, response to initial antimicrobial therapy, and outcome in SARS is much different from CAP, differentiate them will be helpful to early recognition, prompt isolation, and prevention of its spread.