Chinese Trauma Surgeon Association for management guidelines of vacuum sealing drainage application in abdominal surgeries-Update and systematic review.

Vacuum sealing drainage (VSD) is frequently used in abdominal surgeries. However, relevant guidelines are rare. Chinese Trauma Surgeon Association organized a committee composed of 28 experts across China in July 2017, aiming to provide an evidence-based recommendation for the application of VSD in abdominal surgeries. Eleven questions regarding the use of VSD in abdominal surgeries were addressed: (1) which type of materials should be respectively chosen for the intraperitoneal cavity, retroperitoneal cavity and superficial incisions? (2) Can VSD be preventively used for a high-risk abdominal incision with primary suture? (3) Can VSD be used in severely contaminated/infected abdominal surgical sites? (4) Can VSD be used for temporary abdominal cavity closure under some special conditions such as severe abdominal trauma, infection, liver transplantation and intra-abdominal volume increment in abdominal compartment syndrome? (5) Can VSD be used in abdominal organ inflammation, injury, or postoperative drainage? (6) Can VSD be used in the treatment of intestinal fistula and pancreatic fistula? (7) Can VSD be used in the treatment of intra-abdominal and extra-peritoneal abscess? (8) Can VSD be used in the treatment of abdominal wall wounds, wound cavity, and defects? (9) Does VSD increase the risk of bleeding? (10) Does VSD increase the risk of intestinal wall injury? (11) Does VSD increase the risk of peritoneal adhesion? Focusing on these questions, evidence-based recommendations were given accordingly. VSD was strongly recommended regarding the questions 2-4. Weak recommendations were made regarding questions 1 and 5-11. Proper use of VSD in abdominal surgeries can lower the risk of infection in abdominal incisions with primary suture, treat severely contaminated/infected surgical sites and facilitate temporary abdominal cavity closure.

Site-directed mutagenesis of bacterial cellulose synthase highlights sulfur-arene interaction as key to catalysis.

Cellulose is one of the most abundant biological polymers on Earth, and is synthesized by the cellulose synthase complex in cell membranes. Although many cellulose synthase genes have been identified over the past 25 years, functional studies of cellulose synthase using recombinant proteins have rarely been conducted. In this study, we conducted a functional analysis of cellulose synthase with site-directed mutagenesis, by using recombinant cellulose synthase reconstituted in living Escherichia coli cells that we recently constructed (cellulose-synthesizing E. coli, CESEC). We demonstrated that inactivating mutations at an important amino acid residue reduced cellulose production. In this study, an interesting loss-of-function mutation occurred on Cys308, whose main chain carbonyl plays an important role for locating the cellulose terminus. Mutating this cysteine to serine, thus changing sulfur to oxygen in the side chain, abolished cellulose production in addition to other apparent detrimental mutations. This unexpected result highlights that the thiol side-chain of this cysteine plays an active role in catalysis, and additional mutation experiments indicated that the sulfur-arene interaction around Cys308 is a key in cellulose-synthesizing activity. Data obtained by CESEC shed light on the function of cellulose synthase in living cells, and will deepen our understanding of the mechanism of cellulose synthase.

Functional reconstitution of cellulose synthase in Escherichia coli.

Cellulose is a high molecular weight polysaccharide of ß1 → 4-d-glucan widely distributed in nature-from plant cell walls to extracellular polysaccharide in bacteria. Cellulose synthase, together with other auxiliary subunit(s) in the cell membrane, facilitates the fibrillar assembly of cellulose polymer chains into a microfibril. The gene encoding the catalytic subunit of cellulose synthase is cesA and has been identified in many cellulose-producing organisms. Very few studies, however, have shown that recombinant CesA protein synthesizes cellulose polymer, but the mechanism by which CesA protein synthesizes cellulose microfibrils is not known. Here we show that cellulose-synthesizing activity is successfully reconstituted in Escherichia coli by expressing the bacterial cellulose synthase complex of Gluconacetobacter xylinus: CesA and CesB (formerly BcsA and BcsB, respectively). Cellulose synthase activity was, however, only detected when CesA and CesB were coexpressed with diguanyl cyclase (DGC), which synthesizes cyclic-di-GMP (c-di-GMP), which in turn activates cellulose-synthesizing activity in bacteria. Direct observation by electron microscopy revealed extremely thin fibrillar structures outside E. coli cells, which were removed by cellulase treatment. This fiber structure is not likely to be the native crystallographic form of cellulose I, given that it was converted to cellulose II by a chemical treatment milder than ever described. We thus putatively conclude that this fine fiber is an unprecedented structure of cellulose. Despite the inability of the recombinant enzyme to synthesize the native structure of cellulose, the system described in this study, named "CESEC (CEllulose-Synthesizing E. Coli)", represents a useful tool for functional analyses of cellulose synthase and for seeding new nanomaterials.

Cloning of a rat lung fibrogenic factor.

In a previous study a specific single polypeptide has been purified and characterized that it was capable of promoting human embryonic lung 2BS fibroblasts proliferation in vitro, whose N-terminal 15 amino acid have high sequence homology with members of the mammalian chitinase-like protein family. Here the cloning of the gene is reported. Its cDNA contains an open reading frame 1421 bp long and encodes a protein with a characteristic N-terminal 21 amino acid endoplasmic reticulum signal peptide and the putative protein is highly homologous to acidic mammalian chitinase (AMCase) precursor of mouse and human. Recombinant proteins demonstrate chitinolytic activity, therefore the gene is termed as rat AMCase. Sequence analysis indicates that the gene spanned a 46.2 kb region in rat chromosome 2. Its expression in several tissues other than alveolar macrophages suggests that it might play multiple biological roles in vivo. Our findings will facilitate studies on its roles in physiological and pathological processes.