Management of the Uncinate Process in No-Touch Laparoscopic Pancreaticoduodenectomy.

Laparoscopic pancreatoduodenectomy (LPD) is a demanding abdominal operation that necessitates meticulous surgical skills and teamwork. The management of the pancreatic uncinate process is one of the most important and difficult processes in LPD because of its deep anatomical location and difficult exposure. Complete resection of the uncinate process and mesopancreas has become the cornerstone of LPD. In particular, it is even more difficult to avoid positive surgical margins and incomplete lymph node dissection when the tumor is located in the uncinate process. No-touch LPD, which is an ideal oncological operation process fitting the "tumor-free" principle, has been reported by our group previously. This article introduces the management of the uncinate process in no-touch LPD. Based on the multi-angle arterial approach, in this protocol, the median-anterior and left-posterior approaches to the SMA are used to correctly deal with the important vascular structure, the inferior pancreaticoduodenal artery (IPDA), in order to ensure the safe and complete excision of the uncinate process and mesopancreas. For the achievement of the no-touch isolation technique in LPD, the pancreatic head and the blood supply to the duodenal region must be severed at the very early stage of the operation; after that, the tumor can be isolated intact, resection can be performed in situ, and finally, the tissue can be removed en bloc. This paper aims to show the distinctive ways to manage the uncinate process in no-touch LPD and investigate the viability and safety of this approach. Moreover, the technique may increase the R0 resection rate.

Laparoscopic Radical Antegrade Modular Pancreatosplenectomy via Dorsal-Caudal Artery Approach for Pancreatic Neck-Body Cancer.

Laparoscopic radical resection of the pancreatic neck is one of the most complicated radical operations for pancreatic cancer, especially for patients who have had neoadjuvant chemotherapy. Here, we present a technique to perform laparoscopic radical antegrade modular pancreatosplenectomy (L-RAMPS) using the dorsal-caudal artery approach by making full use of the high-definition vision and operation modes of the laparoscope. The innovation and optimization of this operation are provided in the protocol. Priority should be given to the dorsal resection plane, including the dorsal side of the superior mesenteric artery (SMA), the dorsal side of the pancreatic head, the root of the celiac artery (CeA), the ventral side of the left renal vessels, and the renal hilum. On the condition that the operation for pancreatic neck-body cancer is feasible and safe, the second step is to perform tumor resection en bloc surrounding the SMA and CeA from the caudal to the cephalic side to increase the rate of R0 (radical zero) resection and further prognosis.

Laparoscopic Pancreatoduodenectomy for Pancreatic Cancer using In-Situ No-Touch Isolation Technique.

Laparoscopic pancreatoduodenectomy (LPD) is a standard radical operation for pancreatic head malignant tumors by now. Due to the complex laparoscopic resection and reconstruction techniques, it is difficult to perform LPD for patients with locally advanced pancreatic head cancer after neoadjuvant therapy. Our team initiates LPD using the in-situ No-Touch isolation technique. The innovation and optimization of this modified No-Touch isolation technique emphasize exploring the distal section of superior mesenteric vein (SMV) and the left side of the superior mesenteric artery (SMA) prior to evaluating the resectability by subcolonic mesenteric approach, which is an ideal exploring approach. After that, we use the median-anterior, and left-posterior of SMA approaches to cut off the blood flow of the pancreatic head to make the tumor isolated intact, then move and dissect the tumor. It is a process fitting the surgical principle of tumor-free. This article aims to demonstrate the feasibility and safety of performing LPD using the in-situ No-Touch isolation technique, which might elevate the R0 resection rate. It is an oncological ideal operation process.

Production of ramoplanin analogues by genetic engineering of Actinoplanes sp.

Ramoplanins are lipopeptides effective against a wide range of Gram-positive pathogens. Ramoplanin A2 is in Phase III clinical trials. The structure-activity relationship of the unique 2Z,4E-fatty acid side-chain of ramoplanins indicates a significant contribution to the antimicrobial activities but ramoplanin derivatives with longer 2Z,4E-fatty acid side-chains are not easy to obtain by semi-synthetic approaches. To construct a strain that produces such analogues, an acyl-CoA ligase gene in a ramoplanin-producing Actinoplanes was inactivated and a heterologous gene from an enduracidin producer (Streptomyces fungicidicus) was introduced into the mutant. The resulting strain produced three ramoplanin analogues with longer alkyl chains, in which X1 was purified. The MIC value of X1 was ~0.12 µg/ml against Entrococcus sp. and was also active against vancomycin-resistant Staphylococcus aureus (MIC = 2 µg/ml).

Genetic manipulation revealing an unusual N-terminal region in a stand-alone non-ribosomal peptide synthetase involved in the biosynthesis of ramoplanins.

Ramoplanins produced by Actinoplanes are new structural class of lipopeptide and are currently in phase III clinical trials for the prevention of vancomycin-resistant enterococcal infections. The depsipeptide structures of ramoplanins are synthesized by non-ribosomal peptide synthetases (NRPS). Romo-orf17, a stand-alone NRPS, is responsible for the recruitment of Thr into the linear NRPS pathways for which the corresponding adenylation domain is absent. Here, systematical gene inactivation and complementation have been carried out in a Actinoplanes sp. using homologous recombination and site-specific integration methods. A hybrid gene coding for the N-terminal region of the stand-alone NRPS and the A-PCP domains of a heterologous NRPS restored production of ramoplanins. The results elucidate the unusual N-terminal region which is essential for the biosynthesis of ramoplanins.

An efficient and novel screening model for assessing the bioactivity of extracts against multidrug-resistant Pseudomonas aeruginosa using Caenorhabditis elegans.

As a large number of multidrug-resistant bacteria have emerged, and there is an urgent need for the development of new antibacterial agents. In this study, we developed a liquid-based slow killing assay to be carried out in standard 96-well microtiter plates. This screening method was designed to facilitate high-throughput screening of small molecules and extracts. In antibiotic rescue assays, the Caenorhabditis elegans multidrug-resistant Pseudomonas aeruginosa infection model displayed a high degree of drug resistance in vivo and in vitro. We used the method to screen 1,300 extracts, and found 36 extracts (2.7%) which prolonged the survival of infected nematodes, and four (0.3%) of these extracts showed in vitro and in vivo anti-multidrug resistant P. aeruginosa activity. These results indicate that the whole-animal C. elegans multidrug-resistant bacterial model can be used to screen antibacterial compounds, and can also be useful for bioactive compounds which most likely cannot be identified in vitro.

Improvement of antibiotic productivity by knock-out of dauW in Streptomyces coeruleobidus.

Daunorubicin (DNR) is an important anthracycline antibiotic. Its biosynthesis pathway has been well understood, however, the regulation of DNR biosynthesis needs further investigations. An ORF cloned between drrB and dnrX from the genome of a DNR producer, Streptomyces coeruleobidus DM, was named dauW and designated as an orthologous gene with dnrW and drrD. Several plasmids were constructed for over-expression and/or disruption of dauW in DM. Complete disruption of dauW can significantly increase the yield of DNR. We also found that the transcription level of dnrI, a major regulatory protein in the biosynthesis of DNR, and the self-resistance level were improved in dauW knock-out mutant. These results suggested that dauW may be a down-regulatory gene for DNR biosynthesis. Antibiotics productivity in S. coeruleobidus could be improved via regulation of the transcription of dnrI, a SARP regulator. The production of DNR in a high-producer and the yield of epi-DNR in an engineering strain were also increased by disruption of dauW.

Environmentally safe production of 7-ACA by recombinant Acremonium chrysogenum.

7-Amino cephalosporanic acid (7-ACA), which is currently obtained by chemical deacylation from cephalosporin C (CPC), is a major intermediate for industrial production of ß-lactam antibiotics. 7-ACA can also be produced from CPC by enzymatic route including two-step and one-step procedures. In our research, an ecs gene coding for CPC acylase was synthesized and cloned into pET-28a(+) to construct an E. coli expression plasmid pYG232. E. coli BL21(DE3) bearing pYG232 was induced by IPTG and successfully expressed the recombinant ECS (88.9 kDa). Under the optimal conditions: 0.5 mg/ml purified ECS protein, 5 mg/ml CPC, 100 mM Tris-Cl (pH 9.6), supplement with 7 mM Zn(2+), slightly shaking for 6 h at 25°C, the transformation productivity was 54.4%. Then, ecs was cloned downstream of an A. chrysogenum endogenous promotor, PpcbC, to construct pYG233 for expression in A. chrysogenum. pYG233 was introduced into a CPC high-producer via integrative transformation of protoplasts. Two independent bleomycin-resistant transformants were investigated by PCR, Southern blotting, quantitative RT-PCR, western blotting, and fermentation. Although these two transformants both have one copy of integrated ecs, they showed different expression level of ECS protein and 7-ACA production. When concentration of CaCO(3) was reduced to 50 mM, ZnSO(4) was increased to 7 mM, CuSO(4) was eliminated from the fermentation media, and the pH was adjusted to 8.0 at day 4 during fermentation, 7-ACA production of one of the transformants could reach 1701 µg/ml, indicated that more than 30% of CPC produced by this high-producer have been transformed into 7-ACA directly in vivo. This is the highest 7-ACA production by direct fermentation ever reported.

Studies on amino acid replacement and inhibitory activity of a beta-lactamase inhibitory peptide.

An SHV beta-lactamase gene was amplified from a beta-lactam resistant Klebsiella pneumoniae K-71 genomic DNA. After expression and purification, we demonstrated that peptide P1 could inhibit the hydrolysis activity of both TEM-1 and SHV beta-lactamase in vitro. Three mutations were introduced into P1 in which the first residue S was replaced by F, the 18th residue V was mutated to Y, and the 15th residue Y was substituted with A, C, G, and R to obtain the mutants of P1-A, P1-C, P1-G, and P1-R, respectively. The mutant peptides were purified and their inhibitory constants against TEM-1 and SHV beta-lactamase were determined. All these beta-lactamase inhibitory peptides could inhibit the activity of both beta-lactamases, while the mutant peptides showed stronger inhibitory activities against TEM-1 beta-lactamase than against SHV beta-lactamase. Inhibition data suggested that P1-A improved the beta-lactamase inhibitory activity by over 3-fold compare to P1. When P1-A was incubated with K. pneumoniae K-71 in Luria-Bertani medium containing ampicillin, it showed a much stronger growth of inhibition ratio over P1. This study gives us a good candidate for development of novel beta-lactamase inhibitors.

Improvement of cephalosporin C production by recombinant DNA integration in Acremonium chrysogenum.

Cephalosporins are widely used as anti-infectious beta-lactam antibiotics in clinic. For the purpose of increasing the yield of cephalosporin C (CPC) fermentation, especially in an industrial strain, A. chrysogenum genes cefEF and cefG, which encode the ultimate and penultimate steps in CPC biosynthesis, cefT, which encodes a CPC efflux pump, and vgb, which encodes a bacterial hemoglobin gene were transformed in various combinations into an industrial strain of A. chrysogenum. Both PCR and Southern blotting indicated that the introduced genes were integrated into the chromosome of A. chrysogenum. Carbon monoxide difference spectrum absorbance assay was performed and the result showed that Vitreoscilla hemoglobin was successfully expressed in A. chrysogenum and had biological activity. HPLC analysis of fermentation broth of recombinant A. chrysogenum showed that most transformants had a higher CPC production level than the parental strain. Multiple transformants containing an additional copy of cefG showed a significant increase in CPC production. However, cefT showed little effect on CPC production in this high producer. The highest improvement of CPC titer was observed in the mutant with an extra copy of cefG + cefEF + vgb whose CPC production was increased by 116.3%. This was the first report that three or more genes were introduced simultaneously into A. chrysogenum. Our results also demonstrated that the combination of these genes had a synergy effect in a CPC high producer.

Cloning, expression, and characterization of a novel (S)-specific alcohol dehydrogenase from Lactobacillus kefir.

A gene encoding a novel (S)-specific NADH-dependent alcohol dehydrogenase (LK-ADH) was isolated from the genomic DNA of Lactobacillus kefir DSM 20587 by thermal asymmetric interlaced-polymerase chain reaction. The nucleotide sequence of (S)-LK-ADH gene (adhS) was determined, which consists of an open reading frame of 1,044 bp, coding for 347 amino acids with a molecular mass of 37.065 kDa. After a BLAST similarity search in GenBank database, the amino acid sequence of (S)-LK-ADH showed some homologies to several zinc containing medium-chain alcohol dehydrogenases. This novel gene was deposited into GenBank with the accession number of EU877965. adhS gene was subcloned into plasmid pET-28a(+), and recombinant (S)-LK-ADH was successfully expressed in E. coli BL21(DE3) by isopropyl-beta-D-1-thiogalactopyranoside induction. Purified enzyme showed a high enantioselectivity in the reduction of acetophenone to (S)-phenylethanol with an ee value of 99.4%. The substrate specificity and cofactor preference of recombinant (S)-LK-ADH were also tested.

[Construction and culture conditions of dextransucrase-secreting engineered strain].

OBJECTIVE: Dextransucrase was a glucosyltransferases catalyzing the transfer of D-glucopyranosyl units from sucrose to synthesize alpha-glucans or oligosaccharides. METHODS: dexYG gene (GenBank Accession No. DQ345760), encoding the dextransucrase from Leuconstoc mesenteriodes 0326, was subcloned into expression plasmid pET28a(+). The recombinant plasmid was then transformed into E. coli BL21 (DE3). Kanamycin resistant transformants were selected and verified by restriction endonuclease assay. RESULTS: Dextransucrase could be efficiently expressed in engineered strain BL21 (DE3)/pET28-dexYG by Isopropyl beta-D-thiogalactopyranoside (IPTG) induction, although the growth of E. coli host was inhibited during induction. Recombinant enzyme producing conditions such as induction time, IPTG concentration, incubation temperature, cell density (OD(600)) and pH value were studied. The optimum conditions for producing dextransucrase were as follows: incubation at 25 degrees C, 0.5 mmol/L Isopropyl beta-D-thiogalactopyranoside (IPTG) induction at cell density (OD(600)) of 1.0 for 5h, pH 6.0. Under these conditions, the recombinant dextransucrase activity was increased from 5.39U/mL to 35.62 U/mL. The highest activity under the optimal culture conditions after 5h induction in medium with pH 6.0 was 3.5 times as that of in Luria-Bertani medium without pH-adjustment. Moreover, the pH value was one of the main reasons that caused the degradation of enzyme in the later stage of induction. CONCLUSION: These results showed that dextransucrase could be efficiently heterologous expressed in E. coli and a strong dextransucrase activity had been detected.

Cloning, sequencing and expression of a dextransucrase gene (dexYG) from Leuconostoc mesenteroides.

The gene dexYG encoding the dextransucrase from an industrial strain of Leuconostoc mesenteroides 0326 was isolated by PCR. The nucleotide sequence of the dexYG gene consists of an open reading frame (ORF) of 4,584 bp, coding for a 1,527 aa protein with a Mr of 170 kDa. The results were analysed by a BLAST similarity search of the GenBank database, which revealed the amino acid sequence was similiar to dsrD derived from L. mesenteroides Lcc4. The dexYG gene was subcloned into the plasmid pET28a(+) and was expressed in E. coli BL21 (DE3) by IPTG induction. The pH value was one of the main reasons which caused the degradation of enzyme activity in the later stage of induction. The highest activity was reached 36 U/ml after 5 h induction in medium at pH 6.0. Biotransformation yield of the enzyme reached 65% and the molecular weight of transformed dextran was more than 68 kDa in 2 h.

Induction and characterization of adventitious roots directly from the explants of Panax notoginseng.

Adventitious roots from leafstalks and lateral roots were obtained directly from explants of Panax notoginseng. The lateral root explants were more sensitive to the induction of adventitious roots using indole-3-butyric acid. HPLC analysis of saponins extracted from the adventitious roots indicated that several protopanaxatriol saponins were present but ginsenoside Rd was missing, compared with the saponins extracted from the raw herbs. The dry weight of primary adventitious root culture of Panax notoginseng increased 5.25 times during multiplication in a classical shaking-flask system, suggesting that it is a culture system with great potential for scale-up.

Identification of beta-lactamase inhibitory peptide using yeast two-hybrid system.

Random oligonucleotide fragments were designed and amplified by PCR and fused with the activating domain of pGAD424 to construct a random peptide library. The DNA fragment encoding beta-lactamase was fused with the binding domain of pGBT9(+2). Subsequently, using yeast two-hybrid system we found two positive clones encoding peptides P1 and P2 that have the ability to bind beta-lactamase in vivo. The genes encoding P1 and P2 were cloned into pGEX-4T-1. GST-peptide fusion proteins were expressed in Escherichia coli and isolated by glutathione-Sepharose 4B affinity chromatography. Finally, P1 and P2 were cleaved from the fusion protein with thrombin and purified by ultrafiltration. Inhibition assay of peptides with beta-lactamase in vitro indicated that only P1 has the ability to inhibit beta-lactamase.