Advances in the production of chemicals by organelle compartmentalization in Saccharomyces cerevisiae / 生物工程学报

As a generally-recognized-as-safe microorganism, Saccharomyces cerevisiae is a widely studied chassis cell for the production of high-value or bulk chemicals in the field of synthetic biology. In recent years, a large number of synthesis pathways of chemicals have been established and optimized in S. cerevisiae by various metabolic engineering strategies, and the production of some chemicals have shown the potential of commercialization. As a eukaryote, S. cerevisiae has a complete inner membrane system and complex organelle compartments, and these compartments generally have higher concentrations of the precursor substrates (such as acetyl-CoA in mitochondria), or have sufficient enzymes, cofactors and energy which are required for the synthesis of some chemicals. These features may provide a more suitable physical and chemical environment for the biosynthesis of the targeted chemicals. However, the structural features of different organelles hinder the synthesis of specific chemicals. In order to ameliorate the efficiency of product biosynthesis, researchers have carried out a number of targeted modifications to the organelles grounded on an in-depth analysis of the characteristics of different organelles and the suitability of the production of target chemicals biosynthesis pathway to the organelles. In this review, the reconstruction and optimization of the biosynthesis pathways for production of chemicals by organelle mitochondria, peroxisome, golgi apparatus, endoplasmic reticulum, lipid droplets and vacuole compartmentalization in S. cerevisiae are reviewed in-depth. Current difficulties, challenges and future perspectives are highlighted.

Progress in studies on production of chemicals from xylose by Saccharomyces cerevisiae / 生物工程学报

Effective utilization of xylose is a basis for economic production of biofuels or chemicals from lignocellulose biomass. Over the past 30 years, through metabolic engineering, evolutionary engineering and other strategies, the metabolic capacity of xylose of the traditional ethanol-producing microorganism Saccharomyces cerevisiae has been significantly improved. In recent years, the reported results showed that the transcriptome and metabolome profiles between xylose and glucose metabolism existed significant difference in recombinant yeast strains. Compared with glucose, the overall process of xylose metabolism exhibits Crabtree-negative characteristics, including the limited glycolytic pathway activity, which reduces the metabolic flux of pyruvate to ethanol, and the enhanced cytosolic acetyl-CoA synthesis and respiratory energy metabolism. These traits are helpful to achieve efficient synthesis of downstream products using pyruvate or acetyl-CoA as precursors. This review provides a detailed overview on the modification and optimization of xylose metabolic pathways in S. cerevisiae, the characteristics of xylose metabolism, and the construction of cell factories for production of chemicals using xylose as a carbon source. Meanwhile, the existed difficulties and challenges, and future studies on biosynthesis of bulk chemicals using xylose as an important carbon source are proposed.

Regulation of Smad ubiquitination regulatory factor 1 expression by NF-κB / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify a nuclear factor κB (NF-κB) responsive element within the Smad ubiquitination regulatory factor 1 (SMURF1) gene promoter, and to demonstrate its role in the regulation of SMURF1 expression.</p><p><b>METHODS</b>A series of truncated luciferase reporter plasmids of the SMURF1 promoter were constructed and transfected into hepatic cancer Hep G2 cells. Luciferase assays were carried out to assess the activities of such promoters. DNA binding and chromatin immunoprecipitation (ChIP) assays were used to identify an NF-κB responsive element within the SMURF1 promoter. Lucifease plasmid with mutated NF-κB site was constructed and its activity was assessed. The expression of SMURF1 in Hep G2 cells was detected after transfection of NF-κB specific small interfering RNA (siRNA).</p><p><b>RESULTS</b>The SMURF1 promoter showed a high transcription activity, and the region of -519 to -378 was demonstrated to be a positive regulatory region. -411 to -420 of the SMURF1 promoter was an NF-κB responsive element, and NF-κB may specifically bind to this site. Mutation of this element may prominently decrease the activity of the promoter. Transfection of NF-κB siRNA evidently down-regulated SMURF1 expression.</p><p><b>CONCLUSION</b>NF-κB can specifically bind to the -411 to -420 region of the SMURF1 promoter and plays an essential role in the expression of SMURF1.</p>

Trephine transcutaneous osteotomy of talonavicular arthrodesis in the treatment of talonavicular pain / 中华骨科杂志

Objective To evaluate the clinical effect of talonavicular arthrodesis and the influence of adjacent joints use trephine percutaneous osteotomy in the treatment of talonavicular arthralgia.Methods From June 1999 to June 2009,24 patients were performed talonavicular arthrodesis due to a variety of painful disorder of talonavicular joint with trephine percutaneous osteotomy.There were 13 males and 11 females,with an average age of 45 years(range,37-72 years).The indications for the procedure included 15cases with posttraumatic arthritis,6 cases with rheumatoid arthritis,and 3 cases with degenerative arthritis.AOFAS system and visual analogue scale(VAS)were used to evaluate the change of function and arthralgia.Graves score system was used to evaluate the influence of adjacent joints.Results All patients were followed up 10-120 months,with the mean of 48 months.Only one case suffered skin brim necrosis of incision and got delayed healing after 3 weeks.The average AOFAS ankle-hind foot score improved from 45.2 points preoperatively to 84.5 points postoperatively.The excellent and good rate was 87.5%.VAS pain scores decreased from 8.1 to 2.4 postoperatively.Twenty-three patients were satisfied and one dissatisfied with the results.Postoperative radiology showed the union evidence in 23 patients at 6 months postoperatively(successful fusion rate of 95.8%).One joint nonunion occurred and required revision arthrodesis with iliac crest bone graft.There was an increase of Ⅰ grade in arthritic scores for 8 cases and Ⅱ grade for 1 case.Conclusion Talonavicular arthrodesis with trephine percutaneous osteotomy has the advantages of low trauma,high successful fusion rate and can acquire satisfactory clinical effect in the treatment of painful malalignment of talonavicular joints.

Analysis of the vacuum sealing drainage technique combined with sural neurovascular pedicle fascio-cutaneous flap to repair deep wounds in the foot near the ankle joint with exposed bone and tendons / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the practical method of vacuum sealing drainage (VSD) technique combined with sural neurovascular pedicle fasciocutaneous flap to repair deep wounds in the foot near the ankle joint with exposed bone and tendons.</p><p><b>METHODS</b>From January 2006 to January 2009, 79 patients with deep wounds in the foot near the ankle joint with exposed bone and tendons were treated by VSD technique combined with sural neurovascular pedicle fasciocutaneous flap including 58 males and 21 females with an average age of 34 years old ranging from 7 to 59 years. There were 17 cases in low 1/3 part of leg and achilles tendon, 28 in lateral malleolus and lateral dorsum of foot, 21 in medial malleolus and medial dorsum of foot, 13 in heel and pelma. Firstly the wounds were debrided and cultivated by using VSD technique, then the soft tissue defections were repaired with sural neurovascular pedicle fasciocutaneous flap.</p><p><b>RESULTS</b>The area of flap was from 6 cm x 5 cm to 18 cm x 15 cm; All patients stayed in hospital for 14 to 30 days, 18 days in average. Living flaps of all patients were followed-up from 6 months to 3 years, the flaps of 2 patients were mostly necrotic, 3 were necrotic, 5 cases appeared obstacle of venous back streaming. The others survived with no infections.</p><p><b>CONCLUSION</b>The wound would become fresh and clean as soon as possible with VSD. The sural neurovascular pedicle fasciocutaneous flap could provide a good covering for the exposed wound. Therefore the wound healed faster with friction resistance and fine appearance. The time of hospitalization were greatly shortened after combined application.</p>

Trephine arthrodesis of subtalar joints: operative technique and clinical effect / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To review the operative technique of trephine arthrodesis of subtalar joints and evaluate its clinical effect.</p><p><b>METHODS</b>From June 1998 to October 2006, we performed subtalar arthrodesis on 38 feet of 34 patients for a variety of painful disorders of hindfoot with trephine technique. Clinical and radiologic follow-up evaluations were performed for 45 months on average (range, 21 to 110 months) after arthrodesis.</p><p><b>RESULTS</b>No severe complications were found in this study except one patient with dropfoot and two with skin necrosis. The average ankle-hindfoot scores of the American Orthopaedic Foot and Ankle Society (AOFAS) was improved from 48.3 preoperatively to 79.2 postoperatively (P<0.05). The pain scores of visual analogue scales (VAS) decreased from 7.2 (range, 3 to 10) preoperatively to 2.6 (range, 1 to 6) postoperatively (P<0.05). Subjectively, the patients experienced improvements in pain, function, cosmesis, and shoewearing. Overall, 30 patients were satisfied and all patients would have this procedure again under similar circumstances. Postoperative radiology showed that complete union was found in 35 feet 6 months after operation, with the successful union rate of 92.1%. There was an increase in arthritic scores for 5 ankles, 4 talonavicular joints, 4 calcaneocuboid joints, and 4 midfoot joints. Nonunion occurred in 3 subtalar joints with anterolateral approach, which required revision arthrodesis.</p><p><b>CONCLUSION</b>Isolated subtalar arthrodesis with trephine method is an effective procedure for painful malalignment of hindfoot.</p>

Analysis of microsurgical repair of deep wounds of the foot near the ankle joint / 中华创伤骨科杂志

Objective To evaluate simple and practical methods to repair deep wounds in the foot near the ankle joint.Methods 128cases of deep wounds near ankle jo int with exposed bone and tendons fro mJan 1990to Jan 2002were reviewed .Altogether 13types of microsurgical flaps were applied in these cases and obtained satisfactory results.Timing of sur gery:53cases of primary repair,28c ases of secondary repair,47cases of delayed repair.Results26cases of reverse skin avultion were repaired by venous anastomosis in a valsed flaps,of which19survived completely,and 7underg one partial necrosis.There were 19f ree tissue flap grafts in which 13sur vived,3failed and 3undergone partial necrosis and infection.All pedicle tissue flap grafts amounted to 83cases wi th only3partial necrosis in 58cases of sura l nerve flaps graft,and 1total necro sis in 25other types of flap grafts.Con-clusion Sural nerve flaps graft is a reliable method to repair deep wounds with exp osed bone and tendons near the ankle joint.It is easy to perform with excellent abrasion resistance and little effect on the donor limb.

Clinical application of Subtalar joint fusion with trephine / 中华骨科杂志

Objective To introduce a new technique of talocalcaneal joint fusion with trephine and evaluate its clinical effects. Methods From June 1997 to October 2001, 18 cases complained of pain, weakness, limited range of motion and tenderness of ankle were treated with subtalar joint fusion. Of 18 cases, there were 12 males and 6 females with an average age of 47 years (range, 35 to 59 years). The lesions of subtalar joint were identified as traumatic osteoarthritis in 8, degenerative osteoarthritis in 5, congenital bone bridge in 2, rheumatoid arthritis in 2 and refractory inflammation of tarsal sinus. The AP and lateral view X-ray films were taken to measure the width and length of sutalar joint and talocalcaneal angle so as to choose the trephine of appropriate diameter (?11.5 mm, 12 mm, 13 mm )and guide the direction and length of osteotomy. Posterolateral approach was used in 14, and anterolateral approach in 4 depending on the location of lesion at subtalar joint. The trephine was inserted into subtalar joint slowly, the bone block inside the trephine was removed, rotated to 90?, then reimplanted in situ in 14 cases; Autograft of iliac crest was harvested and implanted by trephine in 4. Results All of the affected feet were immobilized with a cast postoperatively for 12 to 16 weeks. The patients were followed up for an average of 25 months ranging from 5 months to 4 years. All the wounds healed well at 2 weeks, the callus appeared at 4 weeks, and the bony fusion was obtained at 16 weeks displayed by postoperative X-ray films. The scores of ankle pain by VAS measurement were improved from preoperative 83.8 to postoperative 32.5. There were no severe complications, only 1 case suffered from dropping foot and recovered 10 months later, and 1 case complained of discomfort of foot. Conclusion Subtalar joint fusion with trephination is an effective procedure with many advantages such as: minimal invasive surgery, easy to perform, higher fusion rate and preserving mechanical stability of hind foot.