Effects of AH3 and AFt on the Hydration-Hardening Properties of the C4A3S¯-CS¯-H2O System.

This study aimed to reveal the effects of the hydration products AH3 and AFt phases on the hydration and hardening properties of calcium sulfoaluminate (CSA) cement. In addition, the effects of anhydrite (CS¯) and gypsum (CS¯H2) on the properties of CSA cement were compared. Calcium sulfoaluminate (C4A3S¯) was synthesized with analytical reagents, and the C4A3S¯-CS¯-H2O system with different molar ratios of CS¯ and C4A3S¯ was established. The phase compositions and contents of AFt and AH3 were determined by X-ray diffraction (XRD), Rietveld quantitative phase analysis, and thermogravimetric analysis (TG). The effects of pore structure and hydration product morphology on mechanical properties were analyzed by mercury intrusion porosity (MIP) and scanning electron microscopy (SEM). The results showed that the compressive strength exhibited a correlation with the AH3 content. In the case of relatively sufficient anhydrite or gypsum, C4A3S¯ has a high degree of hydration, and the AH3 content can be considered to contribute more to the strength of the hardened cement paste. When anhydrite was selected, the combined and interlocked AFt crystals were covered or wrapped by a large amount of AH3. The mechanical properties of the hardened cement paste mixed with anhydrite were better than those of that mixed with gypsum.

The Crystal Structure and Molecular Docking of CYP76AH3 in the Tanshinone Biosynthesis Pathway / 中国生物化学与分子生物学报

Salvia miltiorrhiza is widely used in the treatment of the angina pectoris, coronary heart disease and myocardial infarction. CYP76AH3 is the key P450 enzyme, locating at the branch point of the tanshinone synthesis pathway. The crystal structural study and key amino acid analysis are of great significance for synthetic biology study on tanshinone. But it is always a challenge for scientists to carry out protein purification, crystallization and crystal structural studies on transmembrane type Ⅱ P450 enzymes. In this study, the prokaryotic expression plasmid was generated, and the high-purity target protein was purified. CYP76AH3 was successfully crystallized, and the crystal structure was solved.After docking range was determined by Cavityplus analysis, molecular docking with Discovery Studio was conducted. The docking result indicated that Gly298 and Asp294 had hydrogen bond interaction with the substrate, while Phe479, Leu367 and Leu293 had hydrophobic interaction with the substrate.In addition, the effect of mutations at the key amino acids on the protein structure stability was predicted throung point mutation simulation. This study would provide a target for protein engineering of CYP76AH3 and lay a foundation for the study of synthesis biology on tanshinones.

Excess of Mortality in Adults and Elderly and Circulation of Subtypes of Influenza Virus in Southern Brazil.

PURPOSE: In the elderly population, the influenza infection and its clinical complications are important causes of hospitalization and death, particularly, in longer-lived age. The objective of this study is to analyze the impact of influenza virus circulation on mortality in the elderly and adults, in years with different predominant virus strains. METHODS: We performed a time trend study to evaluated excess of mortality for pneumonia and influenza, respiratory disease, and all-causes in southern region of Brazil, from 2002 to 2015. After considering other models, we opted for Serfling regression. Excess of death rates per 100,000 inhabitants were analyzed in specific age groups (24-59, 60-69, 70-79, ≥80 years) and by year of occurrence. Mortality information were taken from Brazilian Mortality Information System and etiological data were accessed in Sentinel Virological Surveillance database, getting the weekly positivity of the immunofluorescence tests for influenza A (H1N1, H3N2), and B. RESULTS: In southern Brazil, there is an evident seasonal pattern of all death outcomes among different age groups in the dry and cold season (April-September). The highest excess mortality rates occurs among older, particularly in years of circulation of influenza AH3N2, especially among people ≥80 years, in 2003 and 2007-years of great severity of influenza activity. After 2009, with the introduction of the pandemic influenza AH1N1, we observed a lower impact on the mortality of the elderly compared to <60 years. DISCUSSION: A cross reactivity antibody response from past exposure probably provided protection against disease in the elderly. Despite not controlling for comorbidities, climate, and vaccination, for the >70 years, ratio of respiratory diseases excess mortality rates between AH1N1 (2009) and severe year of H3N2 (2007) shows protection in the pandemic year and great vulnerability during AH3N2 virus predominance. CONCLUSION: The reduced immune response to infection, and to vaccination, and presence of comorbidities recommend a special attention to this age group in Brazil. Besides medical assistance, the timeliness of vaccine campaigns, its composition, and etiological surveillance of respiratory diseases are some of the preventive and public health measures.

Aeromonas piscicola AH-3 expresses an extracellular collagenase with cytotoxic properties.

UNLABELLED: The aim of this study was to investigate the presence and the phenotypic expression of a gene coding for a putative collagenase. This gene (AHA_0517) was identified in Aeromonas hydrophila ATCC 7966 genome and named colAh. We constructed and characterized an Aeromonas piscicola AH-3::colAh knockout mutant. Collagenolytic activity of the wild-type and mutant strains was determined, demonstrating that colAh encodes for a collagenase. ColAh-collagen interaction was assayed by Far-Western blot, and cytopathic effects were investigated in Vero cells. We demonstrated that ColAh is a gluzincin metallopeptidase (approx. 100 kDa), able to cleave and physically interact with collagen, that contributes for Aeromonas collagenolytic activity and cytotoxicity. ColAh possess the consensus HEXXH sequence and a glutamic acid as the third zinc binding positioned downstream the HEXXH motif, but has low sequence similarity and distinct domain architecture to the well-known clostridial collagenases. In addition, these results highlight the importance of exploring new microbial collagenases that may have significant relevance for the health and biotechnological industries. SIGNIFICANCE AND IMPACT OF THE STUDY: Collagenases play a central role in processes where collagen digestion is needed, for example host invasion by pathogenic micro-organisms. We identified a new collagenase from Aeromonas using an integrated in silico/in vitro strategy. This enzyme is able to bind and cleave collagen, contributes for AH-3 cytotoxicity and shares low similarity with known bacterial collagenases. This is the first report of an enzyme belonging to the gluzincin subfamily of the M9 family of peptidases in Aeromonas. This study increases the current knowledge on collagenolytic enzymes bringing new perspectives for biotechnology/medical purposes.