ABSTRACT
Objective To compare biomechanical effects of Zero-Profile anterior cervical intervertebral fusion system and Cage-Plate fusion system on the adjacent segments, so as to provide references for the long-term clinical efficacy of single segment cervical spondylosis. Methods The finite element model of cervical spine C1-7 was established based on CT scan data of normal people. After the validity of the model was validated, two finite element models of C5-6 segment implanted with Zero-P fusion system and Cage-Plate fusion system were built. The physiological torque 1.5 N·m was loaded respectively on the normal model, Zero-P implanted model and Cage-Plate implanted model to simulate cervical flexion, extension, lateral bending and rotation. Changes in the ranges of motion (ROMs) of adjacent segments and stresses on nucleus pulposus, endplate and annulus, facet joints of intervertebral disc were compared for the three models. Results After the two kinds of anterior cervical intervertebral fusion systems were implanted, ROMs of C4-5 segments increased by 20%, but ROMs of C6-7 segments increased up to 120%. The stresses on C4-5 nucleus increased by 78%, while the stresses on C6-7 nucleus increased up to 110%. The stresses on the adjacent endplates and the fiber ring also increased. Conclusions The implantation of Cage-Plate and Zero-P fusion system both increased the ROMs of the adjacent segments, and the stresses on annulus, fiber rings and facet joints of the adjacent discs increased as well, which would cause lesions of the adjacent segments in the long run. However, there was no essential difference in biomechanical effects of the Cage-Plate and Zero-P cage fusion system on the adjacent segments.
ABSTRACT
Cyclic diguanosine monophosphate (c-di-GMP) is a ubiquitous nucleotide second messenger present in a wide variety of bacteria. It regulates many important bacterial physiological functions such as biofilm formation, motility, adhesion, virulence and extracellular polysaccharide synthesis. It binds with many different proteins or RNA receptors, one of which is called riboswitch that is usually located at the 5'-untranslational region (5'-UTR) in some mRNA. Riboswitch usually comprises a specific ligand-binding (sensor) domain (named aptamer domain, AD), as well as a variable domain, termed expression platform (EP), to regulate expression of downstream coding sequences. When a specific metabolite concentration exceeds its threshold level, it will bind to its cognate riboswitch receptor to induce a conformational change of 5'-UTR, leading to modulation of downstream gene expression. Two classes of c-di-GMP-binding riboswitches (c-di-GMP-Ⅰ and c-di-GMP-Ⅱ) have been discovered that bind with this second messenger with high affinity to regulate diverse downstream genes, underscoring the importance of this unique RNA receptor in this pathway. Class Ⅰ c-di-GMP riboswitches are present in a wide variety of bacteria, and are most common in the phyla Firmicutes and Proteobacteria, while class Ⅱ c-di-GMP riboswitches typically function as allosteric ribozymes, binding to c-di-GMP to induce folding changes at atypical splicing site junctions to modulate downstream gene expression. This review introduces the discovery, classification, function, and also the affected downstream genes of c-di-GMP riboswitches.
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Objective To evaluate the optimum ratio of medicine dosage for dexmedetomidine mixed with sufentanil used for patient?controlled intravenous analgesia ( PCIA) after Nuss procedure in pedi?atric patients with pectus excavatum. Methods Sixty pediatric patients diagnosed with pectus excavatum, aged 5-12 yr, weighing 18-50 kg, of ASA physical statusⅠorⅡ, scheduled for elective Nuss procedure under general anesthesia, were randomly divided into 3 equal groups using a random number table:different ratios of medicine dosage while dexmedetomidine was added to sufentanil groups ( SD1-3 groups) . Postopera?tive analgesia was as follows: group SD1 received sufentanil 1 μg∕kg + dexmedetomidine 2 μg∕kg; group SD2 received sufentanil 1 μg∕kg + dexmedetomidine 3 μg∕kg; group SD3 received sufentanil 1 μg∕kg +dexmedetomidine 4 μg∕kg. A mixture of tropisetron 0?1 mg∕kg and dexamethasone 0?1 mg∕kg ( in 100 ml of normal saline) was added in each group. The PCA pump was programmed to deliver 0?5 ml with a lockout interval of 15 min and background infusion at 2 ml∕h. The PCA pump was connected immediately after the end of operation, and sufentanil with a dosage of 0?1μg∕kg was used as a rescue analgesic within 48 h post?operatively. The VAS score was maintained below 4. The requirement for rescue analgesics was recorded. The Ramsay sedation scores was recorded at 4, 8, 12, 24 and 48 h postoperatively, and the occurrence of adverse reactions such as nausea and vomiting, bradycardia, over?sedation, respiratory depression, agitation and shivering was recorded within 48 h after surgery. Results No pediatric patients developed nausea and vomiting, respiratory depression, bradycardia, over?sedation, and shivering. No pediatric patients required rescue analgesics in SD2 and SD3 groups. Compared with group SD1 , the requirement for rescue analgesics and incidence of agitation were significantly decreased, and Ramsay sedation scores were increased at 4 and 8 h after operation in SD2 and SD3 groups. Ramsay sedation scores were significantly higher at 4 h after oper?ation in SD3 group than in SD2 group. Conclusion Dexmedetomidine 3 μg∕kg mixed with sufentanil 1μg∕kg is the optimum ratio of medicine dosage when used for PCIA after Nuss procedure in pediatric patients with pectus excavatum.
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Objective To investigate the significance of the expression of endostatin and vascular endothelial growth factor(VEGF)in hepatocellular carcinoma(HCC).Methods The expression of endostatin and VEGF in 46 specimens which were collected at Second Affiliated Hospital of Fnjian Medical University from January 2000 to Apfil 2005 was detected by immunohistochemistry.The relationship between the expression of endostatin and VEGF and the progression of HCC was determined.All data were analyzed via t test,paired t test,Pearson rank correlation coefficient.LSD-t test or Tamhane's-t test.Results The expression of endostatin and VEGF was detected mainly in the cytoplasm of HCC cells and adjacent tissues.The values of mean optical density (MOD)of endostatin in HCC tissue,adjacent tissue and normal liver tissue were 0.11±0.02,0.14±0.0l and 0.09±0.01.respectively,and the values of integrated optical density(IOD)of endostatin in the above mentioned tissues were(1.8±0,2)×10~4,(3.8±2.2)×10~4 and(0.9±0.4)×10~4,respectively.The values of MOD and IOD of endostatin in HCC tissue were significantly lower than those in adjacent tissue(t=2.032,7.927,P＜0.05).The values of MOD of VEGF in HCC tissue,adjacent tissue and normal liver tissue were 0.13±0.02.0.12±0.02 and 0.11±0.02,respectively,and the values of IOD of VEGF were(5.4±3.1)×104,(3.9±2.5)×10~4 and(3.0 ±3.0)×10~4,respectively.The values of MOD and IOD of VEGF in HCC tissue were significantly hisher than those in adjacent tissue(t=5.871,8.723,P<0.05).There was positive correlation between the expression of endostatin and the recurrence of HCC(r=0.669,P<0.05),while VEGF had no influence on the recurrence of HCC(t=0.892,P>0.05).Conclusions Endostatin is mainly expressed in HCC tissue,but the level of its expression is lower in HCC tissue than in adjacent tissue.The expression of VEGF is higher in HCC tissue than in adjaneet tissue.Endostatin,rather than VEGF,may be used as a independent prognostic factor of the prognosis of patients with HCC.
ABSTRACT
In the field of biomechanics, there have been many discoveries concerning the cervical spine injuries in recent years. With the help of biomechanical knowledge, we can not only judge the stability of the cervical spine and have a clear idea of the factors that may affect the stability but also conduct an appropriate classification of the injuries. In this article, we summarize the effects of the stiffness and preinjury biomechanical characteristics of the cervical spine (such as alignment, mass, inertial properties) on the injury, changes of the spinal canal during injury, and the rapidly developing research on finite element models of cervical spine injuries in the past few years.