Production of mucic acid from pectin-derived D-galacturonic acid: a review / 生物工程学报

Mucic acid is a hexaric acid that can be biosynthesized by oxidation of D-galacturonic acid, which is the main constituent of pectin. The structure and properties of mucic acid are similar to that of glucaric acid, and can be widely applied in the preparation of important platform compounds, polymers and macromolecular materials. Pectin is a cheap and abundant renewable biomass resource, thus developing a process enabling production of mucic acid from pectin would be of important economic value and environmental significance. This review summarized the structure and hydrolysis of pectin, the catabolism and regulation of D-galacturonic acid in microorganisms, and the strategy for mucic acid production based on engineering of corresponding pathways. The future application of mucic acid are prospected, and future directions for the preparation of mucic acid by biological method are also proposed.

Biodegradation of furan aldehydes in lignocellulose hydrolysates / 生物工程学报

Lignocellulose is the most abundant renewable organic carbon resource on earth. However, due to its complex structure, it must undergo a series of pretreatment processes before it can be efficiently utilized by microorganisms. The pretreatment process inevitably generates typical inhibitors such as furan aldehydes that seriously hinder the growth of microorganisms and the subsequent fermentation process. It is an important research field for bio-refining to recognize and clarify the furan aldehydes metabolic pathway of microorganisms and further develop microbial strains with strong tolerance and transformation ability towards these inhibitors. This article reviews the sources of furan aldehyde inhibitors, the inhibition mechanism of furan aldehydes on microorganisms, the furan aldehydes degradation pathways in microorganisms, and particularly focuses on the research progress of using biotechnological strategies to degrade furan aldehyde inhibitors. The main technical methods include traditional adaptive evolution engineering and metabolic engineering, and the emerging microbial co-cultivation systems as well as functional materials assisted microorganisms to remove furan aldehydes.

Clinical application of dynamic neutralization system (K-Rod) in treating multisegmental lumbar degenerative disease / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the clinical effects of dynamic neutralization system (K-Rod) in treating multisegmental lumbar degenerative disease.</p><p><b>METHODS</b>From October 2011 to October 2013, 20 patients with multisegmental lumbar degenerative disease were treated with dynamic neutralization system (K-Rod). There were 8 males and 12 females with an average age of 45.4 years old (ranged from 31 to 65) and an average course of 3.8 years (ranged from 9 months to 6.25 years). All patients had the history of low back and legs pain. Among them, 10 cases were far lateral lumbar disc herniation, 7 cases were lumbar spinal stenosis, 3 cases were lumbar spondylolisthesis (degree I in 2 cases and degree II in 1 case). Every patient had only one responsible segment which causing the symptom would have to be rigidly fixed during operations, and the adjacent intervertebral disc of the responsible segments at least 1 segment has already obvious degenerated. All patients underwent the operation to relieve compressed nerves and reconstruct spinal stability with K-Rod system (the responsible segments were fixed with interbody fusion, and the adjacent segments were fixed with dynamic stabilization). Visual analogue scale (VAS), Japanese Orthopaedic Association Scores (JOA) and Oswestry Disability Index (ODI) were used to evaluate the clinical effects. Imaging data were used to analyze the range of motion (ROM), intervertebral disc height and intervertebral disc signal (according to modified Pfirrmann grading system) in degenerative adjacent segment.</p><p><b>RESULTS</b>All patients were followed up for more than 1 year, and preoperative symptoms obviously relieved. There were significant differences in VAS, JOA, ODI between preoperative and postoperative (postoperative at 1 week and 1 year) (P<0.05). Radiological examination showed that all responsible segments had already fused, and no looseness, displacement and breakage of internal fixations were found. Postoperative at 1 year, the ROM of adjacent segments were decreased (P<0.05). There was no significant difference in intervertebral disc height between preoperative and postoperative at 1 year (P>0.05). According to modified Pfirrmann grading system to classification for the 25 disks of adjacent segment, 8 disks (32%) got improvement, 15 disks (60%) got no change and 2 disks (8%) got aggravation at 1 year after operation.</p><p><b>CONCLUSION</b>Dynamic neutralization system (K-Rod) combined with interbody fusion could obtain short-term clinical effects in the treatment of multisegmental lumbar degenerative disease.</p>

Unilateral pedicle screw fixation and intervertebral fusion for the treatment of far lateral lumbar disc herniation / 中国骨伤

<p><b>OBJECTIVE</b>To explore the feasibility and clinical efficacy of unilateral pedicle screw fixation with transforaminal lumbar interbody fusion (TLIF) for the treatment of far lateral lumbar disc herniation.</p><p><b>METHODS</b>From January 2007 to January 2011, 18 patients with far lateral lumbar disc herniation underwent a unilateral TLIF procedure in conjunction with posterior unilateral pedicle screw fixation. There were 13 males and 5 females,ranging in age from 42 to 73 years (means 58.5 years). All cases had single segment involved 5 cases in L3, 4, 10 cases in L4,5,3 cases in LSS. The visual analog scale (VAS) of low back pain and leg pain and Oswestry Disability Index scores were observed in postoperative and followed-up period, and compared with preoperative.</p><p><b>RESULTS</b>The operation of 18 patients was successful,there were no severe complication. The average operative time was 105 min (85 to 125 min), the average amount of blood loss was 145 ml (90 to 340 ml). During the followed-up, the visual analog scale and Oswestry disability index scores were significant improved compared with preoperative (P < 0.05). All patients were followed up from 12 to 48 months with an average of 23 months, there was no implant break and displacement in postoperative X-ray.</p><p><b>CONCLUSION</b>The surgical procedure of unilateral pedicle screw fixation with transforaminal lumbar interbody fusion had the advantage including less invasion, quickly recovery, short operative time, and saving fixation cost, it may provide an alternative treatment for patients with far lateral lumbar disc herniation.</p>

Clinical study of open vertebroplasty in treating thoracolumbar metastatic tumor / 中国骨伤

<p><b>OBJECTIVE</b>To explore the clinical application and therapeutic effect of open vertebroplasty for thoracolumbar metastatic tumor.</p><p><b>METHODS</b>From September 2003 to December 2009, 21 patients with thoracolumbar metastatic tumor underwent the surgical procedure of posterior spinal cord decompression and open vertebroplasty combined with short-segmental pedicle screw fixation during the same intervention. There were 14 males and 7 females, ranging in age from 48 to 73 years with the mean of 59.5 years and ranging in course of disease from 1 to 4 months with an average of 2.5 months. The primary focus of the tumor of 19 cases were established, lung carcinoma was in 8 cases, breast cancer in 4 cases, prostate carcinoma in 4 cases, hepatocarcinoma in 2 cases and thyroid carcinoma in 1 case. The primary focus of 2 cases could not be established. The spinal function according to Frankel grade, grade B was in 4 cases, C in 6, D in 5, E in 6. The lumbar-back pain, height of anterior and posterior vertebral body, Cobb angle and spinal function were recorded before and after operation.</p><p><b>RESULTS</b>The operation of all patients was successful, there were no severe complications and aggravation of spinal function. The VAS score of lumbar-back pain decreased from 8.78 +/- 0.45 preoperatively to 2.25 +/- 0.36 postoperatively. Among 16 cases combined with pathological fracture, the height of anterior spinal vertebral body increased from (12.7 +/- 2.1) mm preoperatively to (19.5 +/- 3.9) mm postoperatively; the height of posterior spinal vertebral body increased from (14.1 +/- 1.8) mm preoperatively to (20.3 +/- 2.3) mm postoperatively; Cobb angle decreased from (26.0 +/- 8.9) degrees preoperatively to (6.0 +/- 0.9) degrees postoperatively. There was significant difference above items between before and after operation (P < 0.05). The spinal function according to Frankel grade at final follow up, grade C was in 2 cases, D in 4, E in 15. All patients were followed up from 5 to 28 months with an average of 14 months, there was no loosening and breakage of internal fixity, 15 cases died during follow-up period.</p><p><b>CONCLUSION</b>The surgical intervention can effectively preserve spinal instability and alleviate the spinal cord symptoms, improve the life quality of patients. It may provide an alternative treatment for patients in poor general health and shorter life expectancy.</p>

The clinical value of percutaneous vertebroplasty in the treatment of osteoporotic vertebral fractures for the elderly patients aged 80 years and over / 中华老年医学杂志

Objective To estimate the clinical value of percutaneous vertebroplasty (PVP)performed on the elderly patients aged 80 years and over with osteoporotic vertebral fractures.Methods Since January 2000, 19 patients aged 80 years and over were treated with PVP, and 17 patients from 60 to 79 years old underwent percutancous kyphoplasty (PKP). Visual analogue scale (VAS) was tested preoperatively and 1 to 7 days, 3 months, 6 months, 1 year and 2 years after operation. The time of radiation, volume of bone cement injection and hospital charges were compared betwecn two procedures. Results Over the 2-year follow-up, there were no significant differences in analgesia effects between thc two groups (P＞0.05). The radiation time of PVP and PKP was (107±37)s and (151±76)s respectively (t=2.24, P＜0.05). The hospital charges of PVP and PKP were ￥(16 124±5850) and ￥(34 265±6655) respectively (t=9.26,P＜0.01). Conclusions PVP is better than PKP for treating osteoporotic compression fractures in the elderly patients over 80 years, because of the former's simplicity and efficiency.

Enhancing stability of Trichoderma reesei xylanase (XYN II) by site-directed mutagenesis / 生物工程学报

We engineered a disulphide bridge between two adjacent double-layered beta-sheet at the N-terminal region of Trichoderma reesei endo-1,4-beta-xylanase II(XYN II) by site-directed mutagenesis. The native xylanase XYN-OU and the mutated xylanase XYN-HA12 (T2C, T28C and S156F) were separately expressed in Pichia pastoris. Both xylanases were purified and characterized. The optimum temperature of XYN-HA12 was increased from 50 degrees C to 60 degrees C, relative to XYN-OU. At 70 degrees C, the halftime of inactivation for XYN-OU and XYN-HA12 were 1 min and 14 min, respectively. The optimum pH of XYN-HA12 was 5.0, similar to XYN-OU. However, XYN-HA12 could retain over 50% activity from pH 3.0 to 10.0 at 50 degrees C for 30 min. As for XYN-OU, it could retain over 50% activity from the pH value 4.0 to 9.0 at 50 degrees C in 30 min. The result of the mutated xylanase indicated that constructed disulphide bridge could improve its thermostability at relatively higher temperature.

Research on compensatory of contralateral vertebral artery by MRA in unilateral stenosis / 中国医师进修杂志

Objective To evaluate the MRA by measuring the diameter of the stenosis artery and the contralateral normal vertebral artery with unilateral stenosis. Methods Seventeen-six patients were divided into normal group and vertebral arterial type of cervical spondylosis group.Among 26 vertebral arterial type of cervical spondylosis cases,13 cases appeared as vertebral arterial type with unilateral stenosis of ≤1.6 mm in diameter .Statistics assessment of MRA in stenosis and contralateral artery was engaged. Results The unilateral artery stenosis diameter measured

The clinic diagnosis and surgical outcome of thoracic myelopathy caused by ossification of ligamenta flava / 中华骨科杂志

Objective To study the diagnosis of thoracic myelopathy caused by ossification of ligamenta flava(OLF) and the influence of the improved surgical procedure on clinic effect. Methods From October 1994 to December 1999, 14 patients with thoracic myelopathy secondary to OLF were diagnosed and treated by improved procedure. The chief clinic manifestation of the disease were insidious and progressive onset of numbness, sensory loss of lower extremities or trunk, motor weakness, gait disturbance and imbalance, hyperreflexia and sphincter dysfunction. 41 levels of OLF were found by means of plain radiography,MRI associated with CT or CTM and were resected.There were 4 levels at T 8-9, 10 levels at T 9-10, 11 levels at T 10-11 and 5 levels at T 11-12. OLF were removed by means of improved posterior “floating”procedure that open “window”at cranial and caudal end and cut“bridge”at left and right side of ossified mass. The latest results were assessed according to JOA scale score system and recovery ratio. the preoperative average JOA scale score was 4.1 point (range 1 to 8 points). Results 14 patients were followed up from 6 to57 months with an average of 23 months. The postoperative average JOA scale score was 9.4 point (range 5 to 11), the recovery ratio was 76.8% and the excellent and good results was 85.6%. The average amount of blood loss was 370 ml and the average operative time was 175 minutes. Conclusion Clinic history and neurological examination associated with MRI and CT or CTM was the important means of the diagnosis of OLF, improved surgical technique was more effective and reliable.オ