Single chain antibody fragment (scFv) is a small molecule composed of a variable region of heavy chain (VH) and a variable region of light chain (VL) of an antibody, and these two chains are connected by a flexible short peptide. scFv is the smallest functional fragment with complete antigen-binding activity, which contains both the antibody-recognizing site and the antigen-binding site. Compared with other antibodies, scFv has the advantages of small molecular weight, strong penetration, low immunogenicity, and easy expression. Currently, the most commonly used display systems for scFv mainly include the phage display system, ribosome display system, mRNA display system, yeast cell surface display system and mammalian cell display system. In recent years, with the development of scFv in the field of medicine, biology, and food safety, they have also attracted much attention in the sectors of biosynthesis and applied research. This review summarizes the advances of scFv display systems in recent years in order to facilitate scFv screening and application.
Animals ; Immunoglobulin Variable Region/genetics* ; Immunoglobulin Fragments/metabolism* ; Single-Chain Antibodies/metabolism* ; Peptide Library ; Mammals/genetics*

Objective:To investigate regional homogeneity(ReHo)and whole brain functional connectivity(FC)in patients with mild cognitive impairment(MCI), and to explore the mechanisms of MCI in the resting state.Methods:Resting-state functional magnetic resonance imaging(RS-fMRI)was performed on 24 patients with MCI and 30 age, gender and nationality-matched normal controls.Abnormal brain areas in the MCI group were screened and analyzed by using the DPARSFA2.3 and SPM8 software programs.Whole brain FC analysis was performed with the posterior cingulate cortex(PCC)/precuneus as the seed points.Results:Compared with the control group, MCI subjects displayed higher ReHo values in the frontal-middle-Left, precentral-Left, postcentral-Left, rolandic-opercular-Left, and frontal-inferior-opercular-Left and lower ReHo values in the temporal-superior-right, temporal-middle-right, postcentral-right, and temporal -pole -superior -right(Voxel level, Alphasim correction, P<0.05). Whole brain FC analysis showed greater functional connectivity of PCC/precuneus with fusiform-right, thalamus-right, lingual-right and parahippocampal-right in subjects with MCI, and less functional connectivity of the PCC/precuneus with temporal-middle-Left, angular-Left, temporal-superior-Left and occipital-middle-Left in subjects with MCI(Voxel level, Alphasim correction, P<0.05). Conclusions:Abnormalities of the default mode network may be associated with the onset of MCI, and abnormalities in posterior cingulate/precuneus connectivity may be helpful in finding imaging evidence with high sensitivity to MCI.

Objective:To investigate the mechanism of subjective cognitive decline(SCD)in resting-state by using regional homogeneity(ReHo)and functional connectivity(FC)in SCD patients.Methods:Resting-state functional magnetic resonance imaging(RS-fMRI)was performed in 25 SCD patients and 30 normal controls matched by sex, education and nationality.DPARSFA2.3 and SPM8 software were used to analyze and screen the brain areas with abnormal ReHo values in SCD group, with the posterior cingulated(PCC)/paruneus as seed points for whole-brain FC analysis.Results:Compared with the normal control group, the SCD group showed that ReHo values of right occipital gyrus and left precuneus were increased, and ReHo values of right inferior temporal gyrus, right orbital inferior frontal gyrus and bilateral thalamus were decreased(Voxel level, Alphasim correction, P<0.05). Using PCC/ precuneus as seed voxels, the whole brain functional connectivity analysis showed that the functional connectivity with cerebelum Crus 2 R was increased, and the functional connectivity with right orbital inferior frontal gyrus, left inferior temporal gyrus and temporal pole was reduced(Voxel level, Alphasim correction, all P<0.05). Conclusions:Default mode network may play an important role in the mechanism of SCD, and abnormalities in brain areas may first occur in PCC/precuneus.

Objective To compare the efficacy and safety of diazepam combined with olanzapine in treatment of agitation symptoms in patients with alcohol withdrawal delirium tremors( DT) . Methods Total-ly 60 inpatients with DT according to CCMD-3 were enrolled in a 7-day,with 30 patients in the diazepam group ( control group) and 30 patients in diazepam combined with olanzapine group ( research group) . The delirium rating scale( DRS-R-98) was used to evaluate the severity of the delirium symptoms. The positive and negative syndrome scale excited component( PANSS-EC) was used to assess the agitation symptoms. The treatment emergent symptom scale ( TESS) was used to assess the safety and the vital signs. Results There was no significant difference in the delirium recovery time between the two groups(M(QR):24 h(24 h)vs 24 h(6 h))(Z=-0. 45,P=0. 65). The PANSS-EC score in research group(17. 00±2. 67) was significant low-er than that in control group(19. 80±2. 43) at the 6 hours after treatment(t=4. 26,P<0. 01),but there were no significant difference between the two groups at the baseline,24 h,48 h and 72 h(P>0. 05) . One case of dizziness,2 cases of lethargy in the control group;1 case of nasal congestion,5 cases of drowsiness,3 cases of constipation, 3 cases of dry mouth, 1 case of abnormal liver function in the research group. Conclusion The combination of olanzapine with diazepam can not reduce the recovery time of DT,but can quickly improve the agitation behavior.

Objective: To develop a method for determination of metabolites of diphenylmethane diisocyanate (MDI) in urine, i.e. methylenedianiline (MDA) by high performance liquid chromatography-tandem mass (LC-MS-MS) . Methods: Urine samples were prepared by hydrolyzation with sulfuric acid and extraction by acetonitrile, and then separated on a Shim-pack XR-ODS column, analyzed with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) . The external solvent standard calibration were tested. Results: The linearity ranges were 0.05~20.00 μg/L, The related coefficients were 0.999 5. The limit of detection was 0.02 μg/L. The rats of recovery were 91.0%~103.4%. The relative standard deviations were between 2.7%~7.3%. Conclusion The method was sensitive, accurate and suitable for the MDA determination in urine of MDI exposed population.

Objective To explore the memory function and the effects of sleep on memory consolidation in patients with stable paranoid schizophrenia.Method Sixty patients with stable paranoid schizophrenia were randomly assigned into research group (n =30) and control group (n =30).30 healthy people were raised as a healthy control group.The polysomnography (PSG) was used for 10 hours of sleep monitoring in the research group and the healthy control group and the muhiple memory assessment scale(MMAS) was used to test the subjects memory before and after the sleep monitoring.Control group performed memory tests in equal length daytime.Pre-test and post-memory measurements were compared.Results The prememory test of three groups had significant statistical differences (F(2.87) =31.40,39.89;P＜0.01).Both the auditory verbal/picture memory conservation rate and recognition accuracy rate between research group and healthy controls had no statistically significance differences (P＞0.05).But compared with the control group,auditory verbal memory conservation rate ((62.64±9.06) ％ vs (43.00±9.73) ％,P＜0.01),recognition accuracy rate ((69.11±11.04)％ vs (61.78±11.67)％,P＜0.05),picture memory conservation rate((71.20±14.95) ％ vs (58.72 ± 16.19) ％,P＜ 0.01),recognition accuracy rate ((86.89 ± 8.02) ％ vs (78.89 ±12.63) ％,P＜0.01) of the research group showed statistical significance differences (P＜0.05).Both N2 (r=0.377,P＜0.05) and REM (r=0.436,P＜0.05) had positive correlation with recognition accuracy rate of auditory verbal memory in research group.Conclusion Stable paranoid schizophrenic patients have poorer memory function(auditory verbal words memory recall,picture memory recall) than healthy people.Sleep promotes the consolidation of memory in patients with schizophrenia.Both N2 and REM of patients with stable paranoid schizophrenic have positive correlation with recognition accuracy rate of auditory verbal memory.

To investigate the mutation site of pathogenic gene in patients with hypertrophic cardiomyopathy (HCM) and to analyze the relationship between the genotype and clinical phenotype. Methods: Targeted exon capture sequencing was conducted in a HCM proband for 30 coding exons related HCM gene by all exon amplification and high-throughput sequencing. Furthermore, Sanger sequencing was performed in other family member and in 200 healthy volunteers for verification. The familial investigation included in clinical presentation, physical examination, electrocardiogram and echocardiography. Results: There were 3/6 blood relatives carrying cardiac myosin-binding protein gene MyBPC3 G772A heterozygous mutation, the mutation site was at 258 amino acid of MyBPC3 as glutamic acid (Glu) was substitute to lysine (Lys), such mutation was not found in rest of family member and not in healthy volunteers. The onset of proband and her daughter was rather late, they had palpitation and chest tightness; echocardiography showed interventricular septum basal segment thickening (16-18) mm. Proband was complicating paroxysmal ventricular tachycardia, malignant arrhythmia and heart failure, the maximum pressure gradient of left ventricular outflow was 56 mmHg, which with the high risk for sudden death. Conclusion: Comprehensive gene test has been helpful for clinical stratification, early diagnosis and treatment. MYBPC3 site mutation c.G772A might be the pathogenic mutation in that specific HCM family.

Objective To explore the gray matter changes in aggressive patients with schizophrenia,and the relationship between the gray matter and aggression in patients.Methods Eighteen aggressive patients with schizophrenia (SZ1),18 age-and gender-matched un-aggressive patients with schizophrenia (SZ2) and 18 normal controls (NC) were enrolled in the study.Then a 3.0 T magnetic resonance imaging (MRI) scan was conducted for each participant.The voxel-based morphometry (VBM) approach and the Chinese version of Buss & Perry aggression questionnaire (B&P) were used to explore imaging data and to assess the aggression,respectively.Results Compared with NC,patients with schizophrenia showed changes in gray matter volume (GMV) in the frontal,temporal and the occipital lobes (P＜0.05,AlphaSim corrected).Compared with SZ2,SZ1 showed increased GMV in the right supramarginal gyrus,right postcentral gyms,bilateral insula and orbito-frontal gyri (P＜0.05,AlphaSim corrected).The GMV of the right insula,right postcentral gyms and right supramarginal grus were positively associated with B&P scores in patients with schizophrenia (P＜0.01,AlphaSim corrected),respectively.Conclusions These preliminary findings support that the aggression in schizophrenia is associated with GMV changes of brain regions in patients with schizophrenia.The right postcentral gyrus,the right insula and the right supramarginal gyrus may be involved in the neural mechanism of aggression in schizophrenia.

Objective: To establish ion chromatography method to determine thiocyanate within urine of workers who were exposed to cyanide. Methods: After the workers work, used 50 ml centrifuge tube to collect the urine of workers about 20 ml.The urine were tested by centrifugation, dilution and filtration by C₁₈ column, thiocyanate was separated by AS₁₆ and mobile phase elution by KOH, detected by electrical circuitryconductivity detector, quantitative by the standard curve method. Results: The linear correlation coefficient of thiocyanate within the range of 0.1-5.0 μg/ml was more than 0.999. The method detection limit was 0.11μg/ml (in 1ml urine) , the method quantitative limit was 0.35 μg/ml. The method recoveries were 95.1%-99.7%. The within-day precision range was 0.54%-2.05%, The between-run precision range was 2.06%-5.09%. Sample stability test showed that thiocyanate samples could be stored for 5 days at room temperature and 7 days at 4 ℃, could be stored for 14 days at-20 ℃. Conclusion The technical indicator of method compliance with rule of Guide for establishing occupation health standards-Part 5: determination methods of chemicals in biological materials (GBZ/T 210.5-2008) , the method applies to workers who were exposed to cyanide.