As internal protein elements , inteins are self-excised from their host protein and catalyze ligation of exteins with a peptide bond .They are widely found in all the three domains of the biological kingdom , and in viral proteins .Intein-mediated protein splicing is a posttranslational autocatalytic process that does not require auxiliary enzymes or cofactors . Protein splicing involves four intramolecular reactions and a small number of key catalytic residues in the intein and exteins . The development of expressed protein ligation ( EPL ) and protein trans-splicing ( PTS ) is assisted by inteins and protein splicing.This review introduces the biosynthesis of backbone-cyclized peptides libraries , and describes the applications of cyclic polypeptides and their prospective applications in the future .

Objective To evaluate the efficacy and safety of actovegin against acute oral mucositis through a randomized controlled multicenter trial for nasopharyngeal carcinoma(NPC) patients treated by chemo-radiotherapy. Methods From February 2006 to May 2007,a total of 161 patients with newly diagnosed stage Ⅱ-ⅣA(1992 Fuzhou Stage) NPC were randomly assigned to the prevention group,the treatment group and the control group. All patients received current chemo-radiotherapy ± neoadjuvant chemotherapy. Radiation technique and dose were similar among the three groups. Intravenous infusion of aeovegin was started when radiation started in the prevention group and when grade 2 mueositis occurred in the treatment group,which was given 30 ml daily ,5 times per week until the end of radiotherapy. Criteria of NCI CTC 2.0 and VRS were used to evaluate acute oral mueositis and pain degree,respectively. Results 154 patients were eligible for the efficacy analysis,including 49 in the prevention group,53 in the treatment group and 52 in the control group. In the prevention group and the control group, the incidence was 31% and 56% (P=0.011) for grade 3-4 mucositis,59% and 83% (P=0.009) for grade 2-3 pain. In the treatment group and the control group,the corresponding number was 38% and 60% (P=0.023) ,70% and 90%, (P=0.014). The prevention group had a lower incidence(P=0.021) and longer average interval(P=0.009) of grade 2 mucositis when comparing with the control group. No drug-related adverse event was observed. Conclusions Prophylactic or therapeutic use of actovegin by intravenous infusion can significantly reduce the severity of ehemo-radiotherapy induced oral mucositis and pain. The prophylactic use may also postpone and decrease the incidence of grade 2 mucositis,which deserves clinic application.

Objective To design and construct a new non-fusion soluble expression vector pTIG-mSUMO(small ubiq-uitin-related modifier) using the widely used solubility promoting protein SUMO and based on the translational coupling phenomenon in order to enable the non-fusion soluble expression of the broad-spectrum antiviral protein RA in Escherichia coli by pTIG-mSUMO.Methods The smt3 gene coding for SUMO protein was cloned from yeast genome DNA by PCR. After directed-site silent mutation to eliminate the EcoRⅠsite, the mutant mSUMO was inserted into pET-22b to obtain the translational coupling expression vector pTIG-mSUMO.The RA was subject to PCR amplification and cloned into the pTIG-mSUMO to obtain the expression plasmid pTIG-mSUMO/RA which was supposed to direct the soluble expression of RA by the translational coupling with mSUMO.Results A translational coupling expression vector pTIG-mSUMO which could di-rect/drive the SUMO and heterogonous protein non-fusion expression simultaneously was designed and constructed.The Western blotting result indicated that pTIG-mSUMO could direct the high-level expression of RA, around 40%of which was soluble.Conclusion A translational coupling expression vector pTIG-mSUMO is obtained.After coupling with SUMO, RA is highly expressed in E.coli and both the expression level and solubility are greatly improved.pTIG-mSUMO might contrib-ute to soluble expression of other proteins.

Objective To study the phylogenetic evolution and genetic variations of gag gene among the prevalent human immunodeficiency virus (HIV )‐1 strains in Guangxi Zhuang Autonomous Region . Methods Plasma samples of 158 HIV‐1 infected patients in Guangxi area were collected during October 2011 to March 2012 .The gag gene fragments of HIV‐1 were amplified by reverse transcription/nested‐polymerase chain reaction and then sequenced .MEGA 5 .03 was utilized to construct phylogenetic tree and to calculate the genetic distances and selection pressures (globle ω) of gag gene and its coding regions . The comparisons between two groups were tested by Student′s t test ,and the comparisons of multiple groups were tested by one‐way ANOVA .Results A total of 140 amplification products of gag gene were obtained from 158 samples .Four subtypes of HIV‐1 were found ,including CRF01_AE (80 ,57 .1% ) , CRF08_BC (46 ,32 .9% ) ,CRF07_BC (10 ,7 .1% ) ,and subtype B (B′) (4 ,2 .9% ) .The genetic distances of gag gene of the above subtypes were 0 .036 ± 0 .001 ,0 .031 ± 0 .002 ,0 .043 ± 0 .003 and 0 .102 ± 0 .006 ,respectively ,with statistical significance (F=220 .62 ,P<0 .01) .The p17 and p24 coding regions suffered negative selection pressure (globleω<1) .Neither the globle ω in p17 region nor that in p24 region had significant differences among different subtypes (F=0 .761 ,P=0 .469 and F=0 .037 ,P=0 .964 , respectively ) . Conclusion CRF01_AE is the major subtypes of HIV‐1 in Guangxi Zhuang Autonomous Region .The coding regions of gag gene are relatively conserved during evolution .Changes of HIV‐1 prevalence ,however ,may affect the genetic variation of gag gene ,which should be continuously monitored .

We reconstructed the erythromycin macrocyclic lactone (6-deoxyerythronolide B, 6dEB) synthesis pathway in Escherichia coli. We first cloned all the genes needed to synthesize the 6dEB into multi-gene co-expressed vectors. Then using the recognition sequences of isoschizomers Xba I/Spe I of vectors, we assembled the related genes into a series multiple-genes recombinant plasmids pBJ144, pBJ130. The recombinant plasmids pBJ144, pBJ130 were cotransformed into BAP1 to get the recombinant BAP1(pBJ144/pBJ130). SDS-PAGE analysis showed that individual genes were expressed correctly. After inducing at low temperature, adding propionate as substrate, we validated the crude product by mass spectrometry and the 6dEB yield was about 10 mg/L. These results indicated that the synthetic pathway of 6dEB was successfully assembled and reconstructed in Escherichia coli, which will greatly facilitate the reconstruction of whole erythromycin synthesis pathway and finally help to establish a stable research platform for developing of new derivatives of erythromycin and combinatorial biosynthesis of polyketide-type antibiotics.
Anti-Bacterial Agents ; biosynthesis ; Cloning, Molecular ; Electrophoresis, Polyacrylamide Gel ; Erythromycin ; analogs & derivatives ; biosynthesis ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics

Objective To investigate the HIV-1 drug resistance in Guangxi during 2009 to 2012 and to analyze the correlations between drug resistance and HIV-1 subtypes.Methods Patients with human immunodeficiency virus infection or acquired immune deficiency syndrome ( HIV/AIDS) were randomly re-cruited from different areas in Guangxi.HIV-1 RNA was extracted from blood samples of the subjects and converted into complementary DNA ( cDNA) by using reverse transcription.The pol gene was amplified and sequenced.Subtyping analysis was performed by using the online analysis tool of Genotyping in combination with the MEGA 5.03 software.The HIV resistance mutations were determined and scored with the use of Stanford HIV Drug Resistance Database.Results A total of 196 pol gene sequences were obtained from 103 antiretroviral therapy (ART)-treated subjects (52.55%) and 93 ART-na?ve subjects (47.45%).The 196 pol gene sequences were classified into four subtypes including CRF01_AE, CRF08_BC, CRF07_BC and B, accounting for 48.47%, 44.90%, 6.12%and 0.51%, respectively.The HIV drug resistance rates in sub-jects with and without ART were 10.68% and 7.53%, respectively.Among the 196 subjects, 14 cases showed low level of drug resistance, 3 cases showed moderate level of drug resistance and 4 cases showed high level of resistance.Only one case was resistant to both nucleoside reverse transcriptase inhibitors ( NR-TIs) and non-nucleoside reverse transcriptase inhibitors ( NNRTIs) .The resistance rates of the 196 cases to protease inhibitor (PIs), NRTIs, NNRTIs, and integrase inhibitors (INs) were 6.63%, 3.06%, 11.22%and 8.67%, respectively.The frequencies of PIs-related mutations in subtypes CRF01_AE, CRF07_BC and CRF08_BC were 6.32%, 41.67% and 2.27%, respectively.Most of the PI-related A71V/T mutations were identified in strains belonging to subtype CRF07_BC, accounting for 75% of all A71V/T mutations found in the 196 strains.The NNRTI-related E138A mutations only appeared in strains belonging to subtype CRF08_BC.Conclusion The drug resistance rate among patients with HIV-1/AIDS in Guangxi was higher than the average level in China.The drug resistance rates varied with the subtypes of HIV-1 strains.

Objective: To investigate the clinical outcomes of skin and soft tissue expansion in the repairment of neck scar. Methods: From March 2009 to May 2018, 15 patients with postburn scar contractures on neck, were admitted to the Department of Burn and Plastic Surgery, Karamay Central Hospital of Xinjiang. The patients include 12 males and 3 females, aged 12 to 48 years, with the mean age of 31 years. The scars were at 9 cm×6 cm-14 cm×11 cm in size. The tissue expander of 100-300 ml was placed subcutaneously, in the normal skin area on neck, on one or each side at the first stage operation. The first expander infusion was performed 10-14 days after surgery. The tissue expansion remains for 3-9 months, with an interval of 10 days of each infusion. After the tissue fully expanded, the expander was maintained for 1 month. At the second stage, the expander was removed, and the expanded flap was transferred to repair the wound. Results: The expander exposure due to friction occurred in 2 patients. The final therapeutic effect was not affected, because of iodine gauze bandage. Blood supply of expanded flaps was good in other patients. The size of the expanded flaps was 12 cm×8 cm-16 cm×15 cm. All flaps survived after the second stage surgery. Patients were followed up for 0.5-5 years after surgery. The color and texture of flaps was similar to adjacent normal skin. Conclusions Skin and soft tissue expansion is a safe and effective method in repairing neck scar.

Objective:To evaluate the effect of sirtuin 3 (SIRT3) overexpression on hypoxia-reoxygenation (H/R) injury to hippocampal neurons of mice exposed to high glucose and its relationship with SOD2.Methods:The normally cultured HT22 neurons at the logarithmic phase were selected and divided into 3 groups ( n=12 each) using a random number table method: high-glucose normoxia group (HG group), high glucose+ H/R group (HHR group) and high glucose+ H/R+ SIRT3 overexpression group (HHR+ SIRT3 group). To establish high glucose model, the neurons in 3 groups were cultured in high-glucose culture medium (glucose concentration of 50 mmol/L) for 8 h. In HHR and HHR+ SIRT3 groups, the cells were exposed to glucose-free and hypoxia for 6 h and then cultured in the high-glucose normoxic environment for 24 h to establish the high glucose and HR injury model.In HHR+ SIRT3 group, the neurons were transfected with SIRT3 overexpressed lentivirus.The cell viability was recorded by the cell counting kit-8 assay, reactive oxygen species (ROS) content was detected by flow cytometry, mitochondrial malonaldehyde (MDA) content, superoxide dismutase (SOD) activity, catalase (CAT) activity and adenosine triphosphate (ATP) content were determined by colorimetry, mitochondrial membrane potential (MMP) was detected by JC-1 probe, and the expression of nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), SIRT3, SOD2 and acetylated SOD2 (ac-SOD2) was detected by Western blot. Results:Compared with HG group, cell viability, SOD activity, CAT activity, ATP content, MMP, NRF1 and the expression of TFAM and SIRT3 were significantly decreased, and ROS content, MDA content and ac-SOD2/SOD2 ratio were increased in group HHR and group HHR+ SIRT3 ( P<0.05). Compared with HHR group, cell viability, SOD activity, CAT activity, ATP content, MMP, NRF1 and the expression of TFAM and SIRT3 were significantly increased, and ROS content, MDA content and ac-SOD2 /SOD2 ratio were decreased in HHR+ SIRT3 group ( P<0.05). Conclusion:SIRT3 overexpression can alleviate hypoxia-reoxygenation (H/R) injury to hippocampal neurons of mice incubated in high glucose medium, and the mechanism is related to activation of SOD2 deacetylation.

Objective:To evaluate the role of G-rich RNA sequence binding factor 1 (GRSF1) in cerebral ischemia-reperfusion (I/R) injury in mice and the relationship with ferroptosis.Methods:Twenty-four clean-grade male C57BL/6 mice, aged 8-10 weeks, weighing 20-25 g, were divided into 4 groups ( n=6 each) using a random number table method: sham operation group (Sham group), cerebral I/R group (IR group), cerebral I/R+ GRSF1 overexpression group (IR+ LV-GRSF1 group), and cerebral I/R+ GRSF1 overexpression+ glutathione peroxidase 4 (GPX4) inhibitor group (IR+ LV-GRSF1+ RSL3 group). The model of middle cerebral artery occlusion was developed by thread-occlusion method in anesthetized animals. In IR+ LV-GRSF1 group, GRSF1-overexpressed lentivirus 2 μl was injected into the lateral ventricle at 7 days before the development of the model. GPX4 inhibitor RSL3 5 mg/kg was intraperitoneally injected for 2 consecutive days before the development of the model in IR+ LV-GRSF1+ RSL3 group. After 24 h of reperfusion, the percentage of cerebral infarction volume was determined by TTC assay, the survival neurons in ischemic area were detected by Nissl staining, and brain tissues in ischemic area were obtained for determination of the expression of p16, p21(markers of senescence) and tumor necrosis factor-alpha (TNF-α, senescence-associated secretory phenotype) mRNA (by quantitative real-time polymerase chain reaction), contents of malondialdehyde (MDA), superoxide dismutase(SOD) and glutathione (GSH) (by enzyme-linked immunosorbent assay) and expression of GRSF1, GPX4, Acyl-CoA synthetase long-chain family member 4 (ACSL4) and ferritin (by Western blot). Results:Compared with Sham group, the percentage of cerebral infarction volume was significantly increased, the count of viable neurons was decreased, the expression of p16, p21 and TNF-α mRNA in ischemic brain tissues was up-regulated, SOD and GSH contents were decreased, the MDA content was increased, the expression of GRSF1 and GPX4 was down-regulated, and the expression of ACSL4 and ferritin was up-regulated in IR group ( P<0.05). Compared with IR group, the percentage of cerebral infarction volume was significantly decreased, the count of viable neurons was increased, the expression of p16, p21 and TNF-α mRNA in ischemic brain tissues was down-regulated, SOD and GSH contents were increased, the MDA content was decreased, the expression of GRSF1 and GPX4 was up-regulated, and the expression of ACSL4 and ferritin was down-regulated in IR+ LV-GRSF1 group ( P<0.05). Compared with IR+ LV-GRSF1 group, the percentage of cerebral infarction volume was significantly increased, the count of viable neurons was decreased, the expression of p16, p21 and TNF-α mRNA in ischemic brain tissues was up-regulated, SOD and GSH contents were decreased, the MDA content was increased, the expression of GRSF1 and GPX4 was down-regulated, and the expression of ACSL4 and ferritin was up-regulated in IR+ LV-GRSF1+ RSL3 group ( P<0.05). Conclusions:GRSF1 is involved in the endogenous protective mechanism against cerebral I/R injury by up-regulating GPX4 expression, attenuating oxidative stress, and thus inhibiting ferroptosis in mice.

ICU-acquired weakness (ICU-AW) is a common complication in the intensive care unit (ICU). The occurrence of ICU-AW directly leads to prolonged ICU stays for critically ill patients, and in severe cases, it continues to affect their quality of life even after discharge. This article provides a comprehensive review of the research progress on ICU-AW based on domestic and foreign studies, aiming to provide a scientific overview of ICU-AW, including its definition, pathophysiology, diagnosis, screening tools, influencing factors, and potential intervention strategies, so as to promote timely planning and implementation of relevant screening and intervention measures.