Structure-based mining of a chitosanase with distinctive degradation mode and product specificity.

Chitosan derivates with varying degrees of polymerization (DP) have attracted great concern due to their excellent biological activities. Increasing the abundance of chitosanases with different degradation modes contributes to revealing their catalytic mechanisms and facilitating the production of chitosan derivates. However, the identification of endo-chitosanases capable of producing chitobiose and D-glucosamine (GlcN) from chitosan substrates has remained elusive. Herein, an endo-chitosanase (CsnCA) belonging to the GH46 family was identified based on structural analysis in phylogenetic evolution. Moreover, we demonstrate that CsnCA acts in a random endo-acting manner, producing chitosan derivatives with DP ≤ 2. The in-depth analysis of CsnCA revealed that (GlcN)3 serves as the minimal substrate, undergoing cleavage in the mode that occupies the subsites - 2 to + 1, resulting in the release of GlcN. This study succeeded in discovering a chitosanase with distinctive degradation modes, which could facilitate the mechanistic understanding of chitosanases, further empowering the production of chitosan derivates with specific DP. KEY POINTS: • Structural docking and evolutionary analysis guide to mining the chitosanase. • The endo-chitosanase exhibits a unique GlcN-producing cleavage pattern. • The cleavage direction of chitosanase to produce GlcN was identified.

Biochemical Characterization of a GH46 Chitosanase Provides Insights into the Novel Digestion Specificity.

Endo-chitosanases (EC 3.2.1.132) are generally considered to selectively release functional chito-oligosaccharides (COSs) with degrees of polymerization (DPs) ≥ 2. Although numerous endo-chitosanases have been characterized, the digestion specificity of endo-chitosanases needs to be further explored. In this study, a GH46 endo-chitosanase OUC-CsnPa was cloned, expressed, and characterized from Paenibacillus sp. 1-18. The digestion pattern analysis indicated that OUC-CsnPa could produce monosaccharides from chitotetraose [(GlcN)4], the smallest recognized substrate, in a random endo-acting manner. Especially, the enzyme specificities during chitosan digestion including the regulation of product abundance through a transglycosylation reaction were also evaluated. It was hypothesized that an insertion region in OUC-CsnPa may form a strong force to be involved in stabilizing (GlcN)4 at its negative subsite for efficient hydrolysis. This is the first comprehensive report to reveal the digestion specificity and subsite specificity of monosaccharide production by endo-chitosanases. Overall, OUC-CsnPa described here highlights the previously unknown digestion properties of the endo-acting chitosanases and provides a unique example of possible structure-function relationships.

New Insights into Bifunctional Chitosanases with Hydrolysis Activity toward Chito- and Cello-Substrates.

In the present study, we carried out a comprehensive investigation of glycoside hydrolase (GH) 46 model-chitosanases based on cleavage specificity classification to understand their unknown bifunctional activity. We for the first time show that GH46 chitosanase CsnMHK1 from Bacillus circulans MH-K1, which was previously thought to be strictly exclusive to chitosan, can hydrolyze both chito- and cello-substrates. We determined the digestion direction of bifunctional chitosanase CsnMHK1 from class III and compared it with class II chitosanase belonging to GH8, providing insight into unique substrate specificities and a new perspective on its reclassification. The results lead us to challenge the current understanding of chitosanase substrate specificity based on GH taxonomy classification and suggest that the prevalence from the common bifunctional activity may have occurred. Altogether, these data contribute to the understanding of chitosanase recognition and hydrolysis toward chito- and cello-substrates, which is valuable for future studies on chitosanases.

[Improved on Nitrogen Removal of Anaerobic Ammonia Oxidation by Coupling Element Sulfur-based Autotrophic Short-cut Denitrification].

In order to enhance the removal of NO3--N in the ANAMMOX process, an element sulfur-based autotrophic short-cut denitrification (short-cut S0-SADN) was introduced by adding elemental sulfur to an ANAMMOX continuous flow reactor. The effects of different influent NH4+-N/NO2--N ratios on the nitrogen conversion and NO2--N competitive characteristics in the coupled system were investigated at (33±2)℃ and a pH of 7.8-8.2. The results showed that under different influent NH4+-N/NO2--N ratios (1:1.3, 1:1.5, 1:1, and 1:1.1), the average total nitrogen (TN) removal efficiency of the coupled system reached 96.78%, 97.21%, 94.68%, and 97.72%, respectively, which were much higher than the highest TN removal efficiency of the ANAMMOX theory (89%). Among them, the stable operation of deep nitrogen removal of the short-cut S0-SADN coupled with ANAMMOX was successfully achieved with an influent NH4+-N/NO2--N ratio of 1:1 or 1:1.1. Under the optimal influent NH4+-N/NO2--N ratio of 1:1.1, the concentrations of influent NH4+-N and NO2--N were 240 mg·L-1 and 265 mg·L-1, respectively, the TN removal rate reached 1.50 kg·(m3·d)-1, and the TN removal efficiency of ANAMMOX and S0-SADN pathways were stable at (95.68±1.22)% and (2.04±0.77)%, respectively. During the entire operational process, ANAMMOX always occupied an absolute advantage in the competition of substrate NO2--N, and the activity of ANAMMOX bacteria (NH4+-N/VSS) was stable at (0.166±0.008)kg·(kg·d)-1.

Preparation of sludge-based hydrochar at different temperatures and adsorption of BPA.

This study sought a new way to utilize sludge as a low cost and efficient adsorbent. Preparation of sludge adsorbent by hydrothermal carbonization was done at different temperatures (160-250 °C). Various characterization techniques were used in this study including elemental analysis, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The adsorption performance of the organic matter was analyzed by adsorption experiments with the endocrine disruptor bisphenol A (BPA). Results showed that as the hydrothermal temperature increased, the solid yield of hydrochar decreased from 84.73% to 55.19%, and the maximum specific surface area was 11.9 m2/g. Elemental analysis showed that the hydrochar contains more aromatic carbon than the raw sludge. It was found using the FT-IR and XPS that the hydrochar retains a large amount of oxygen-containing functional groups on the surface after hydrothermal treatment. Hydrochar can be used as an organic-pollutant adsorbent in water; it has a good adsorption effect on BPA and the removal rate can reach 96%. The adsorbed hydrochar can be hydrothermally retreated and returned to the sewage treatment plant for reuse.

A comprehensive review of thermal comfort studies in urban open spaces.

Urban open spaces provide various benefits to large populations in cities. Since thermally comfortable urban open spaces improve the quality of urban living, an increasing number of studies have been conducted to extend the existing knowledge of outdoor thermal comfort. This paper comprehensively reviews current outdoor thermal comfort studies, including benchmarks, data collection methods, and models of outdoor thermal comfort. Because outdoor thermal comfort is a complex issue influenced by various factors, a conceptual framework is proposed which includes physical, physiological and psychological factors as direct influences; and behavioral, personal, social, cultural factors, as well as thermal history, site, and alliesthesia, as indirect influences. These direct and indirect factors are further decomposed and reviewed, and the interactions among various factors are discussed. This review provides researchers with a systematic and comprehensive understanding of outdoor thermal comfort, and can also guide designers and planners in creating thermally comfortable urban open spaces.

[Phosphate Adsorption from Water on CaO2-loaded Magnetic Diatomite].

In this study,magnetic diatomite was used as a carrier to load calcium peroxide(CaO2) nanoparticles,fabricating a high efficiency phosphate adsorption and recovery composite material(MDCP).The micromorphology, inner structure,crystalline constituents and element composition of MDCP were characterized by SEM,EDX-mapping,XRD, XDS, and VSM,respectively.The adsorption isotherm data of MDCP exhibited good agreement with the Langmuir isotherm model. According to the Langmuir model,when T=20℃,the maximum monolayer phosphate adsorption capacities can reach 191.84mg·g-1 for MDCP. The isotherm and kinetics studies showed that MDCP has a regulating effect on the pH of the solution,which can maintain the pH of the solution at the level where adsorption of phosphate occurs on MDCP as a chemisorption process. pH plays a important role on the adsorption of phosphate by MDCP,the pH of effective adsorption ranges from 4 to 10,and the pH of the adsorbed solution can still be maintained in the range of 7 to 9.The MDCP exhibited a high selective adsorption for phosphate in the presence of anions,including Cl-, SO42-, CO32-, HCO32-, F-, and NO3-.The recovered MDCP could be desorbed by HCl solution,and after desorption, the phosphate removal rate of MDCP after re-loading CaO2 could still reach 70% of the initial adsorption.

Transformation and migration of phosphorus in excess sludge reduction pretreatment by alkaline ferrate oxidation combined with anaerobic digestion.

Recently, more and more attention has been paid to the strong oxidation ability of newly prepared potassium ferrate (NAPF) in sludge reduction process, but less attention has been paid to the change of phosphorus in this process. The feasibility of phosphorus migration and transformation during excess sludge reduction pretreatment using NAPF pre-oxidation combined with anaerobic digestion was investigated. After 70 mg/g suspended solids NAPF pretreatment and 16 days anaerobic digestion, the solid-phase volatile suspended solids decreased by 44.2%, and much organic matter had been released into the liquid-phase and then degraded during digestion by indigenous microorganisms. As the sludge pre-oxidation process was performed, solid-phase organic phosphorus and chemically combined phosphorus also released into the liquid-phase as PO43-, peaking at 100 mg/L. During anaerobic digestion, the Fe3+ in the liquid-phase was gradually reduced to Fe2+, and then formed Fe2+-PO43- compound crystals and re-migrated to the solid-phase. The concentration of PO43- decreased to 17.08±1.1 mg/L in the liquid-phase after anaerobic digestion. Finally, the phosphorus in the Fe2+-PO43- compound accounts for 80% of the total phosphorus in the solid-phase. A large number of vivianite crystals in sludge were observed. Therefore, this technology not only effectively reduces sludge, but also increases the proportion of PO43- in the sludge in the form of Vivianite.

Reference-Based Benefits for Colonoscopy and Arthroscopy: Large Differences in Patient Payments Across Procedures but Similar Behavioral Responses.

This study examines how reference-based benefits (RBB) affect patient out-of-pocket payments across outpatient procedures. The California Public Employees' Retirement System (CalPERS) implemented RBB asymmetrically for outpatient procedures in 2012, only applying RBB to outpatient procedures performed in a hospital outpatient department (HOPD), and not applying RBB to outpatient procedures performed in a lower cost ambulatory surgery center. Using claims data (2009-2013) on arthroscopy and colonoscopy services, we found that for colonoscopy, CalPERS patients paid an average of 63.9% (p < .01) more for HOPDs than ambulatory surgery centers in 2012. For arthroscopy, no statistically different cost sharing was found on average. However, high-priced HOPDs were 17.3% and 17.9% less likely to be chosen by CalPERS patients in 2012 for colonoscopy and arthroscopy, respectively. These magnitudes increased in 2013 to 25.2% and 24.2% less, respectively. Overall, responsiveness to RBB with regard to the most expensive HOPDs was similar despite varying cost sharing by procedure.

Impact of Reference Pricing on Cost and Quality in Total Joint Arthroplasty.

BACKGROUND: Prices for total joint arthroplasty vary widely. Insurers have experimented with reference-based benefit designs (reference pricing) to control costs by setting a contribution limit that covers lower-priced facilities but necessitates higher out-of-pocket payments at higher-priced facilities. The purpose of this study was to evaluate the impact of reference pricing on the cost and quality of care for total joint arthroplasty. METHODS: The California Public Employees' Retirement System (CalPERS) implemented reference pricing for total joint arthroplasty in January 2011. We obtained data on 2,023 CalPERS patients who underwent total joint arthroplasty from January 2009 to December 2013 and comparison group data on 8,024 non-CalPERS patients from the same time period. Trends in 9 cost and quality-related metrics were compared between the CalPERS group and the comparison group: patient choice of a lower-priced hospital, insurer payment, consumer payment, 90-day complication rate, 90-day readmission rate, annual surgical volume of the chosen hospital, length of stay, travel distance, and rate of discharge to home. The impact of reference pricing was estimated with difference-in-differences multivariable regressions, adjusting for covariates. RESULTS: An increase of 19 percentage points (95% confidence interval [CI], 13.0 to 25.6 percentage points; p < 0.01) in the selection of lower-priced hospitals was attributable to reference pricing, with a concurrent mean savings for the insurer of $5,067 (95% CI, $2,315 to $7,819; p < 0.01) and an increase in the mean patient out-of-pocket payment of $1,991 (95% CI, $1,053 to $2,929; p < 0.01). No significant change in any quality indicator was attributable to reference pricing, with the exception of an 8% reduction (95% CI, 3.3% to 12.7% reduction; p < 0.01) in the length of stay for hip replacement. CONCLUSIONS: Reference pricing motivates patients to choose lower-priced hospitals for total joint arthroplasty, with no measurable adverse impact on quality. Reference pricing represents a viable strategy in the shift toward value-based care.

Opioid-prescribing Outcomes of Medicare Beneficiaries Managed by Nurse Practitioners and Physicians.

BACKGROUND: Primary care providers are at the center of the opioid epidemic. Whether nurse practitioners (NPs) have different opioid-prescribing outcomes from physicians is not known. OBJECTIVE: To examine opioid-prescribing outcomes of Medicare beneficiaries receiving care from NPs and physicians in primary care. RESEARCH DESIGN: We used Medicare data from 2009 to 2013 and a propensity score-weighted analysis. SUBJECTS: Beneficiaries residing in states in which NPs are able to prescribe controlled substances without physician oversight and who did not have a cancer diagnosis, hospice care, or end-stage renal disease. MEASURES: First, we measured whether beneficiaries received any opioid prescription. Second, for beneficiaries who received opioids, we measured acute (<90 d supply) and chronic (≥90 d supply) use at baseline (2009-2010) and follow-up (2012-2013). Third, we measured potential misuse of opioid prescribing using a daily morphine milligram equivalent dose of >100 mg, overlapping prescriptions of opioids >7 days, and overlapping prescriptions of opioids with benzodiazepines >7 days. RESULTS: Beneficiaries managed by NPs were less likely to receive an opioid [odds ratio (OR), 0.87; P<0.001], were less likely to be acute users at baseline (OR, 0.84; P<0.001), and were more likely to receive a high daily opioid dose of morphine milligram equivalent >100 mg compared with physician-managed beneficiaries (OR, 1.11; P=0.048). CONCLUSIONS: Findings suggest educational programs and clinical guidelines may require approaches tailored to different providers. Future research should examine the contributing factors of these patterns to ensure high-quality pain management and guide policy makers on NP-controlled substance-prescribing regulations.

Medication adherence, costs, and ER visits of nurse practitioner and primary care physician patients: Evidence from three cohorts of Medicare beneficiaries.

OBJECTIVE: To compare medication adherence, cost, and utilization in Medicare beneficiaries attributed to nurse practitioners (NP) and primary care physicians (PCP). DATA: Medicare Part A, B, and D claims and beneficiary summary file data, years 2009-2013. STUDY DESIGN: We used propensity score-weighted analyses combined with logistic regression and generalized estimating equations to test differences in good medication adherence (proportion of days covered (PDC >0.8); office-based and specialty care costs; and ER visits. DATA EXTRACTION: Beneficiaries with prescription claims for anti-diabetics, renin-angiotensin system antagonists (RASA), or statins. PRINCIPAL FINDINGS: There were no differences in good medication adherence (PDC >0.8) between NP and PCP attributed beneficiaries taking anti-diabetics or RASA. Beneficiaries taking statins had a slightly higher probability of good adherence when attributed to PCPs (74.6% vs 75.5%; P < 0.05). NP attributed beneficiaries had lower office-based and specialty care costs and were less likely to experience an ER visit across all three medication cohorts (P < 0.01). CONCLUSIONS: Examining the impact of NP and PCP provided care on outcomes beyond the primary care setting is important to the Medicare program in general but will also help practices seeking to meet benchmarks under alternative payment models that incentivize higher quality and lower costs.

The moral hazard effects of consumer responses to targeted cost-sharing.

This paper examines the effects of the reference pricing program implemented by the California Public Employees Retirement System (CalPERS) in 2012. The program uses targeted cost-sharing to incentivize patient price shopping. We find that the program leads to a 10.3% increase in the use of low-price providers and reduces the average cost per procedure by 12.5%. We further estimate that the program reduces medical spending by $218.8 per procedure, which we estimate is approximately 53.7% of the excessive spending that is due to patient choice of higher price providers caused by insurance coverage, at the expense of a $94.3 (or 12.5%) reduction in consumer surplus. The cost savings from the reference pricing program is about two to three times as large as the reduction from implementing a high-deductible health plan, while the accompanying consumer surplus reduction is much smaller under reference pricing.

Elevated levels of protein in urine in adulthood after exposure to the Chinese famine of 1959-61 during gestation and the early postnatal period.

BACKGROUND: Animal models have suggested that undernutrition during gestation and the early postnatal period may adversely affect kidney development and compromise renal function. As a natural experiment, famines provide an opportunity to test such potential effects in humans. We assessed whether exposure to the Chinese famine of 1959-1961 during gestation and early postnatal life was associated with the levels of proteinuria among female adults three decades after exposure to the famine. METHODS: We measured famine intensity using the cohort size shrinkage index and we constructed a difference-in-difference model to compare the levels of proteinuria, measured with a dipstick test of random urine specimens, among Chinese women (n = 70 543) whose exposure status to the famine varied across birth cohorts (born before, during or after the famine) and counties of residence with different degrees of famine intensity. RESULTS: Famine exposure was associated with a greater risk [odds ratio (OR) = 1.54; 95% confidence interval (CI): 1.04, 2.28; P = 0.029) of having higher level of proteinuria among women born during the famine years (1959-61) compared with the unexposed post famine-born cohort (1964-65) in rural samples. No association was observed among urban samples. Results were robust to adjustment for covariates. CONCLUSIONS: Severe undernutrition during gestation and the early postnatal period may have long-term effects on levels of proteinuria in humans, but the effect sizes may be small.

Smoking experimentation among elementary school students in China: influences from peers, families, and the school environment.

The aim of this study was to investigate experimentation with smoking among primary school students in China. Data were acquired from a recent survey of 4,073 students in grades 4 to 6 (ages 9-12) in 11 primary schools of Ningbo City. The questions were adapted from the Global Youth Tobacco Survey (GYTS). Results suggest that although the Chinese Ministry of Education (MOE) encourages smoke-free schools, experimentation with cigarettes remains a serious problem among primary school students in China. Peers, family members, and the school environment play important roles in influencing smoking experimentation among students. Having a friend who smoked, seeing a family member smoke, and observing a teacher smoking on campus predicted a higher risk of experimentation with smoking; the exposure to anti-tobacco materials at school predicted a lower risk of experimentation with smoking. The evidence suggests that public health practitioners and policymakers should seek to ensure the implementation of smoke-free policies and that intervention should target young people, families, and communities to curb the commencement of smoking among children and adolescents in China.

Smoking behaviours and cessation services among male physicians in China: evidence from a structural equation model.

OBJECTIVE: To investigate smoking prevalence and cessation services provided by male physicians in hospitals in three Chinese cities. METHODS: Data were collected from a survey of male physicians employed at 33 hospitals in Changsha, Qingdao and Wuxi City (n=720). Exploratory factor analysis was performed to identify latent variables, and confirmatory structural equation modelling analysis was performed to test the relationships between predictor variables and smoking in male physicians, and their provision of cessation services. RESULTS: Of the sampled male physicians, 25.7% were current smokers, and 54.0% provided cessation services by counselling (18.8%), distributing self-help materials (17.1%), and providing traditional remedies or medication (18.2%). Factors that predicted smoking included peer smoking (OR 1.14 95% CI 1.03 to 1.26) and uncommon knowledge (OR 0.94 95% CI 0.89 to 0.99), a variable measuring awareness of the association of smoking with stroke, heart attack, premature ageing and impotence in male adults as well as the role of passive smoking in heart attack. Factors that predicted whether physicians provided smoking cessation services included peer smoking (OR 0.82 95% CI 0.76 to 0.89), physicians' own smoking (OR 0.87 95% CI 0.81 to 0.93), training in cessation (OR 1.36 95% CI 1.27 to 1.45) and access to smoking cessation resources (OR 1.69 95% CI 1.58 to 1.82). CONCLUSIONS: The smoke-free policy is not strictly implemented at healthcare facilities, and smoking remains a public health problem among male physicians. A holistic approach, including a stricter implementation of the smoke-free policy, comprehensive education on the hazards of smoking, training in standard smoking-cessation techniques and provision of cessation resources, is needed to curb the smoking epidemic among male physicians and to promote smoking cessation services in China.