Objective: To establish a method for determining the molecular weight and molecular weight distribution of Poly(Lactide-co-Glycolide Acid) (PLGA) using Size Exclusion Chromatography-Refractive Index-Multiangle Laser Light Scattering (SEC-RI-MALLS) and Size Exclusion Chromatography-Refractive Index (SEC-RID), and to compare the results obtained from these two methods.
Methods: For SEC-RI-MALLS, tetrahydrofuran was used as the mobile phase, Shodex GPC KF-803L was employed as the chromatographic column with a flow rate of 1 mL·min^-1, column temperature at 30 ℃, and an injection volume of 100 μL. For SEC-RID, tetrahydrofuran was also used as the mobile phase, Agilent PLgel 5 μm MIXD-D was used as the chromatographic column with a flow rate of 1 mL·min^-1, column temperature at 30 ℃, differential detector temperature at 35 ℃, and an injection volume of 20 μL. The molecular weight and molecular weight distribution were calculated using Agilent’s GPC software. The newly established methods were validated methodologically, and the molecular weight and molecular weight distribution of 13 batches of samples were determined.
Results: The precision, accuracy, stability, and repeatability tests for SEC-RI-MALLS showed RSD values of 1.35%, 1.58%, 1.53%, and 1.26%, respectively. The SEC-RID method exhibited good linearity (r=0.999 9), with RSD values for precision, accuracy, stability, and repeatability tests (n=6) of 2.05%, 1.62%, 1.30%, and 2.97%, respectively. The results obtained from SEC-RI-MALLS were lower than those from SEC-RID, and the molecular weight distribution coefficient was smaller, but the results from the paired T-test performed with the value measured by SEC-RID method and the value measured by SEC-RI-MALLS method multiplied a conversion coefficient of 1.5 showed no significant difference between the two methods.
Conclusion: Both methods are stable and reliable, and can be used for the determination of PLGA molecular weight and molecular weight distribution based on the specific situations.

Objective:To established a rapid method for the determination of lactose(C12 H22 O11)content.Methods:The specific rotation([α]20D)of pure lactose was measured with lactose extract product,and the correc-tion coefficient was calculated.The measured rotatory value of the sample was multiplied by the correction coeffi-cient to obtain the mass(g)of lactose in the test product,and the lactose content was calculated.The equivalence of the newly established polarimetric method and the legal test method(HPLC-RID method)for the determination of lactose content was studied.Results:The linear relation of established method was excellent with the range of 0.05-0.20 g·mL-1(r=1.000 0)and the method also had good reproducibility(RSD=0.07％(n=6)).The lactose content of 141 batches samples measured by polarimetry was compared with the results determined by official analytical procedure,and the results showed the relative deviation between the same batches was less than 1.0％.The results of one-way ANOVA also showed that there was no significant difference between two groups(Sig.＞0.05).Conclusion:The performance of polarimetry is comparable to HPLC-RID in the Chinese Pharma-copoeia 2020 Vol Ⅳ.Meanwhile,the polarimetry can reduce the test cost,shorten the test time and meet the requirements of the quality control.

OBJECTIVE To establish HPLC methods with different separation principles to analyze the relevant impurities in the APIs of bivalirudin from seven enterprises, to provide a basis for the comprehensive control of related substances of bivalirudin. METHODS Reversed-phase high performance liquid chromatography(RP-HPLC) was used to separate and analyze 11 kinds of impurities. Hydrophilic chromatography(HILIC)-HPLC was used to control four process impurities. Polymers were determined by size exclusion chromatography(SEC)-HPLC. RESULTS The established RP-HPLC could effectively separate the principal component and 11 impurities, the correction factors of 11 impurities were between 0.8−1.2, the detection concentration of bivalirudin was 0.1 μg·mL−1, and the detection limit was 0.004%. The established HILIC-HPLC could effectively separate the principal components and four process impurities, and the detection concentration of bivalirudin was 0.3 μg·mL−1, and the detection limit was 0.01%. Under SEC-HPLC conditions, the polymer and bivalirudin peaked sequentially, the resolution of the two was 2.9, the detection concentration of bivalirudin was 6 ng·mL−1, and the detection limit was 0.000 6%. Fifteen kinds of known impurities and polymers in 15 batches of samples from 7 enterprises were calculated by the self-control method of principal components, and the impurity contents from different enterprises had a certain correlation with their production processes. CONCLUSION The three different principles of the method have good specificity, high sensitivity, good durability, and reliable results, and can be used for quality control of substances related to bivalirudin.

Objective:To explore the clinical and genetic characteristics of a fetus diagnosed with Congenital myasthenic syndrome type 16 (CMS16).Methods:A couple who had visited Tianjin Medical University General Hospital in February 2018 due to "adverse outcome of two pregnancies" was selected as the study subject. Clinical data was gathered. Peripheral blood and amniotic fluid samples were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. Low-depth whole-genome sequencing was carried out to detect copy number variation (CNV) in the fetus.Results:The couple′s first pregnancy had resulted in a miscarriage at 27 + 5 weeks, when ultrasound had revealed pleural effusion and polyhydramnios in the fetus. Their second pregnancy was terminated at 30 + 5 weeks due to fetal hand malformations, polyhydramnios and pleural fluid. Both couple had denied family history of genetic conditions. For their third pregnancy, no CNV abnormality was detected, whilst a compound heterozygous variants, including a maternally derived c. 3172C>T (p.R1058W) and paternal c. 1431delG (p.K477fs*89) in the SCN4A gene were detected. Based on the guidelines from the American College of Medical Genetics and Genomics, the c. 3172C>T (p.R1058W) was predicted as a likely pathogenic variant (PM1+ PM2_supporting+ PP3+ PP4), whilst the c. 1431delG (p.K477fs*89) was predicted as a pathogenic variant (PVS1+ PM2_supporting+ PP4). Conclusion:The c. 3172C>T (p.R1058W) and c. 1431delG (p.K477fs*89) compound heterozygous variants of the SCN4A gene probably underlay the CMS16 in the third fetus.

Pharmacological activation of the xenobiotic-sensing nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) is well-known to increase drug metabolism and reduce inflammation. Little is known regarding their physiological functions on the gut microbiome. In this study, we discovered bivalent hormetic functions of PXR/CAR modulating the richness of the gut microbiome using genetically engineered mice. The absence of PXR or CAR increased microbial richness, and absence of both receptors synergistically increased microbial richness. PXR and CAR deficiency increased the pro-inflammatory bacteria Helicobacteraceae and Helicobacter. Deficiency in both PXR and CAR increased the relative abundance of Lactobacillus, which has bile salt hydrolase activity, corresponding to decreased primary taurine-conjugated bile acids (BAs) in feces, which may lead to higher internal burden of taurine and unconjugated BAs, both of which are linked to inflammation, oxidative stress, and cytotoxicity. The basal effect of PXR/CAR on the gut microbiome was distinct from pharmacological and toxicological activation of these receptors. Common PXR/CAR-targeted bacteria were identified, the majority of which were suppressed by these receptors. hPXR-TG mice had a distinct microbial profile as compared to wild-type mice. This study is the first to unveil the basal functions of PXR and CAR on the gut microbiome.

Objective:To investigate drug resistance gene in Mycoplasma pneumoniae(MP) and the distribution of 13 respiratory pathogens in bronchoalveolar lavage fluid(BALF) of children with Mycoplasma pneumoniae pneumonia(MPP).Methods:A total of 100 BALF of children with MPP in Peking University Third Hospital and Peking University First Hospital from January 2018 to January 2019 were collected.Fluorogenic quantitative PCR was used to detect nucleic acid and it′s drug resistance gene of MP and multiple PCR method was adopted to detect influenza A virus, influenza A virus-H 1N 1, influenza A virus-H 3N 2, influenza B, human parainfluenza virus, adenovirus, human bocavirus, human rhinovirus, Chlamydia pneumoniae, human metapneumovirus, MP, human coronavirus, and respi-ratory syncytial virus gene, and the results were compared by using Chi square test. Results:In 100 BALF samples, MP and drug resistance gene were detected by fluorogenic quantitative PCR.Totally, 83 cases (83.00%) were MP positive and 78 cases (93.98%) were drug resistant.All of them had the point mutations A2063G in V region of 23S rRNA domain.A total of 13 kinds of respiratory pathogens were detected by multiplex PCR method, and 89 cases (89.00%) were positive.Totally, 79 cases (79.00%) were MP positive, of which 74 cases (74.00%) detected only MP, and 5 cases (5.00%) detected MP combined with other pathogens.Other pathogens were detected in 10 cases (10.00%). The virus detection rate of 0-4 years old group was higher than that of >4-6 years old group ( P=0.042) and >6 years old group ( P=0.002), and the differences were statistically significant. Conclusions:MP can be detected in most BALF samples of MPP children, the drug resistance phenomenon is serious, and the main point mutation is A2063G.There were other respiratory pathogens and 2 or 3 pathogens were detected in a small number of BALF samples.

Objective: To investigate the feasibility and short term clinical efficacy of early minimally invasive treatment of complex pelvic trauma with Starr reduction frame combined with O-arm navigation system. Methods: From June 2017 to December 2018, thirty two patients with Tile C complex pelvic fractures were prospectively divided into two groups according to the random number table. The open treatment group included 17 cases (open reduction and internal fixation group; 10 males and 7 females, age 24-60 years, average 37±6.5 years; according to Tile classification, 8 cases of C1 type, 8 cases of C2 type and 1 case of C3 type; according to the Denis classification of sacral fractures, 9 cases in zone I, 6 cases in zone II and 2 cases in zone III). The combined treatment group included 15 cases (Starr reduction frame group combined with O-arm navigation system, 8 males and 7 females, age 32-57 years, average 40±5.2 years; according to Tile classification, 8 cases of C1 type, 6 cases of C2 type and 1 case of C3 type; according to the Denis classification of sacral fractures, 8 cases in zone I, 5 cases in zone II and 2 cases in zone III). The ilioinguinal and Stoppa approaches were used in the open treatment group, and the anterior and posterior ring injuries were fixed with reconstruction plate screws and hollow screws, respectively. In the combined treatment group, starr frame was used to assist reduction, combined with "O" arm navigation technique, infix internal fixation frame, superior pubic branch screw, sacroilium screw were used to fix the anterior and posterior ring injury. The quality of pelvic fracture reduction was evaluated by the Matta scoring system, and the Majeed score was used to evaluate the clinical efficacy. Results: All patients were followed up for 6 to 12 months. The hospitalization time (45±11 d), operation time (220.0±49.4 min) and fracture healing time (24.0±5.6 weeks) in the open treatment group were longer than those in the combined treatment group (21±9 d, 180.0±24.2 min, 16.1±3.8 weeks), and the intraoperative blood loss (820.0±140.4 ml) was significantly higher than that in the combined treatment group (24.0±10.4 ml)(t=6.651, 2.772, 6.128, 22.874; all P< 0.05). According to Matta scoring system, in the open treatment group, there are 8 excellent cases, 6 good cases, 2 fair cases, 1 poor case, thus the excellent and good rate was 82.4%(14/17). While 9 cases were excellent, 5 good, 1 fair, and the excellent and good rate was 93.3% (14/15) in the combined treatment group. At the latest follow-up, Majeed score was 51-85 points in the open treatment group, including excellent in 8 cases, good in 6 cases, fair in 2 cases, poor in 1 case, thus the excellent and good rate 82.4% (14/17), and the Majeed score was 75-95 points in the combined treatment group, including excellent in 9 cases, good in 5 cases, fair in 1 case, thus excellent and good rate 93.3% (14/15). There was a statistically significant difference between the two groups of Matta score and Majeed score (χ²=0.034, 0.040; P< 0.05). Surgical infection occurred in 4 cases in the open treatment group and healed after debridement and treatment with sensitive antibiotics. The incidence of complications was 23.5% (4/17). In the combined treatment group, 2 cases had anterolateral thigh skin sensory loss after operation, and the symptoms were relieved after mannitol, mecobalamine treatment and removal of internal fixations. One patient had hematoma of the gluteus maximus muscle after operation. The result of angiography showed that the INFIX screw was too long and perforated near the foramen of the ischium, resulting from the injury of the superior gluteal artery. After stopping the use of anticoagulant, intravenous infusion of tranexamic acid, blood transfusion, etc., the patient was cured and discharged from hospital. The incidence of complications was 20.0% (3/15). There was no significant difference in the incidence of complications between the two groups. Conclusion With the help of starr reduction frame, the early reduction and minimally invasive treatment of pelvic fracture can be realized, and the amount of intraoperative bleeding can be reduced. The combined application of "o" arm navigation can improve the accuracy and safety of sacroiliac screw and anterior column screw placement, reduce the radiation dose and frequency of operators and patients, shorten the operation time and improve the curative effect.

Objective: To investigate the incidence of complications following minimal invasive subcutaneous internal fixator (INFIX) for the treatment of anterior pelvic ring instability, and to analyze control measures. Methods: Data of 42 patients with anterior pelvic ring instability who were treated by anterior subcutaneous internal fixation in our hospital from January 2016 to December 2017 were retrospectively analyzed. There were 15 females and 27 males with an average age of 45.4 years (range, 18-67 years). There were 26 traffic injuries, 10 falling injuries, 3 crush injuries and 3 low energy injuries. According to Tile classification, 24 cases of B2 type, 16 cases of B3 type, 1 case of C1 type and 1 case of C2 type. According to Young-Burgess classification, there were 20 cases of LCI, 18 cases of LCII, 1 case of LCIII, 1 case of APCI, 1 case of APCII, and 1 case of VS. Fourteen cases were combined with limb fractures, and 11 cases were combined with thoracic or abdominal injuries requiring surgical treatment, while 16 cases were with brain injuries. For type APC2, LC1, and some LC2 fractures, fixation for the anterior pelvic ring is enough with INFIX technique alone. For some LC2, LC3, or VS fractures, the anterior and posterior ring were both fixed. Postoperative reduction was evaluated by Matta radiological criteria. Lateral thigh numbness and pain, quadriceps muscle power were recorded during follow-up, and clinical efficacy was evaluated by Majeed score at 6 months after operation. Results: All the 42 patients were followed up for 6 to 12 months, with an average of 9.3 months. Matta standard evaluation for fracture reduction showed that 28 cases were excellent, 14 cases good, and the excellent and good rate was 100%. The early complication rate (within 3 month after operation) was 23.8% (10/42) including 6 cases of lateral femoral cutaneous nerve injury and 2 cases of femoral nerve injury. The symptoms were obviously relieved after the treatment of nutrient nerve and hyperbaric oxygen; 1 case had incision infection which was healed after anti-infection therapy and internal plant removal; 1 case suffered from superior gluteal artery injury which was controlled by pressure hemostasis. Six months after surgery, no case had lost reduction. At 6 months follow-up, the Majeed score was 72-96, with an average of 84.96, of which 32 were excellent and 10 were good, thus the excellent and good rate was 100% (42/42). Conclusion INFIX is an effective internal fixation method for the treatment of unstable anterior pelvic ring injury. However, it has a high rate of early complications, among which nerve injury has the highest incidence.

To provide anatomy information for harvesting the posterior tibial artery cutaneous branches-chain flaps. Methods The research was performed from January, 2017 to January, 2018. Anatomic ob-servation on 10 legs from fresh human cadaver were performed. The location of cutaneous branches of the posterior tibial artery was observed and its diameter and length was measured. Five legs were prepared to investigate the cuta-neous branches of posterior tibial artery.The anastomosis of cutaneous branches of posterior tibial artery was observed by PVA-bismuth oxide perfusion for molybdenum target X-ray arteriography in 5 perfused legs. The cutaneous branches with diameter over 0.2 mm in 10 legs of latex perfusion microdissection were included in the statistical analysis.The data were clustered and analyzed to find the location of distant and near cutaneous branches, which was called the gathering point of cutaneous branch vascular plexus. Secondly, the measured data of distal and near seg-ments containing cutaneous branches were compared by t-test.Then the distribution of cutaneous branches of posteri-or tibial artery on the tibiofibular side was compared by Chi-square test.It was considered to be significant if P value was under 0.05. Results ①There were 4.3 cutaneous branches raised from the posterior tibial artery.There was no significant difference on the tibial and ribula side distribution of the cutaneous branches from the posterior tibial artery (P＞0.05).②The distal cutaneous branch clusters was located at about 1/5 of the distal leg and there were 3.6 cutaneous branches raised from the posterior tibial artery. While the proximal clusters was located at 1/3 of the proximal leg and there were 0.7 cutaneous branches raised from the posterior tibial artery.There were no significant differences in the di-ameters (P=0.28) and pedicle length (P=0.14) between distal and proximal cutaneous branches. ③There were the large cutaneous perforators (≥1.0) mm from the posterior tibial artery at (6.37±1.22) cm proximal to the medial malleolus.The diameter and pedicle length of the distal perforators were (1.11±0.09) mm and (6.53±1.51) mm respectively.④The vas-cular chains parallel to the posterior tibial artery were formed via anastomosis of the adjacent cutaneous perforators. Conclusion The cutaneous expenditure of posterior tibial artery is constant, with a certain pedicle length and diameter. There are 2 relatively dense vascular plexus of cutaneous branches. The proximal and distal vascular flaps can be de-signed with these 2 vascular dense points as rotation points.

Objective To investigate the antibacterial effect of Fusidic acid on Mycoplasma pneumoniae and antibiotic resistant Mycoplasma pneumoniae in vitro.Methods Twenty-eight clinical strains of Mycoplasma pneumoniae isolated from patients with respiratory tract infection at Beijing Friendship Hospital Affiliated to the Capital University of Medical Sciences from January to December 2016 and 2 Mycoplasma pneumoniae reference strains were enrolled.The minimum inhibitory concentration (MIC) of Fusidic acid and Azithromycin were determined by using micro-dilution ration method.The chessboard method was used to check the antibacterial effect of combination between Fusidic acid and Azithromycin.The antibacterial activity of the Fusidic acid was evaluated by measuring the antibacterial rate of different concentrations.Results One isolate showed no mutation in 23SrRNA,26 isolates had one point mutation in loci 2063 and 1 isolate had one point mutation in loci 2064 among the 28 clinical isolates.The findings by micro-dilution method results showed that the MIC values of all the clinical isolates with mutations associated with macrolide resistance to Azithromycin were ＞ 1.000 0 mg/L,and the MIC values of all the clinical isolates with no mutations to azithromycin were ＜ 0.500 0 mg/L.The findings by micro-dilution method results showed that the MIC value of Fusidic acid for Mycoplasma pneumonia and drug resistance Mycoplasma pneumoniae was 1.000 0 mg/L.The Fractional Inhibitory Concentration index of Fusidic acid and Azithromycin combination was ≤0.500 0 mg/L.When the concentration of the Fusidic acid was lower than or equal to 32 MIC,the antibacterial effect of Fusidic acid against Mycoplasma pneumoniae increased with its higher concentration.When the concentration of the Fusidic acid was lower than or equal to 8 MIC,the longer the strain was exposed to the drug,the stronger antibacterial effect was against Mycoplasma pneumoniae.Conclusion If the treatment of Mycoplasma pneumoniae infection is not effective or the infection of patient is combined with bacteria,the application or combination of Fusidic acid may inhibit pathogenic bacteria effectively.Of course,how to use Fusidic acid in clinical treatment needs further study and discussion.