A label-free activatable biosensor for in situ detection of exosomal microRNAs based on DNA-AgNCs and hairpin type nucleic acid probes

Exosomal microRNA (miRNA) is a potential biomarker for cancer diagnosis, metastasis, and treatment. In situ detection of exosomal miRNA is an attractive option due to its simplicity and high accuracy. However, in situ exosomal miRNA detection has encountered challenges because of the low target abundance of targets and limited probe permeability. Herein, a label-free and activatable biosensor was developed for in situ exosomal miRNA assays by utilizing hairpin-shaped nucleic acid probes and DNA-hosted silver nanoclusters (DNA-AgNCs). The probe is directly internalized into the exosomes, and then hybridized with the target miRNA-21. Subsequently, the DNA-AgNCs are pulled closer to the G-rich sequence, ultimately leading to in situ red fluorescence activation. The biosensor not only can detect exosomal miRNA-21 but also distinguish cancer cells from normal cells. Under optimal reaction conditions, the detection limit (LOD) of exosomal miRNA-21 is 1.53 × 107 particles per mL. Furthermore, DNA-AgNCs are used as label-free signal elements for in situ detection of exosomal miRNAs for the first time, expanding the application of nanomaterials in this field. This strategy does not require tedious RNA extraction steps and expensive instruments, and may develop into a non-invasive diagnostic tool for ovarian cancer.

[Comparison between laparoscopic-assisted natural orifice specimen extraction surgery and conventional laparoscopic surgery for left colorectal cancer: 5-year follow-up results of a randomized controlled study]

Objective: To evaluate the long-term efficacy of laparoscopic-assisted natural orifice specimen extraction surgery (NOSES) colectomy using Cai tube for treating left-sided colorectal cancer. Methods: This was a randomized controlled trial. Inclusion criteria were as follows: preoperative pathological diagnosis of left-sided colorectal adenocarcinoma (rectal, sigmoid colon, descending colon, or left transverse colon cancer with the caudad margin ≥8 cm from the anal margin); preoperative abdominal and pelvic computed tomography (or magnetic resonance imaging) showing maximum tumor diameter <4.5 cm; and BMI <30 kg/m2. Patients with synchronous multiple primary cancers or recurrent cancers, a history of neoadjuvant chemoradiotherapy, preoperative evidence of significant local infiltration, distant metastasis, or complications such as intestinal obstruction and intestinal perforation, or who were not otherwise considered suitable for laparoscopic surgery were excluded. A random number table was used to randomize sequential patients to NOSES surgery using Cai tube (non-assisted incision anal sleeve: patent number ZL201410168748.2) (NOSES group) or traditional laparoscopic-assisted surgery (CLS group). Relevant clinical data of the two groups of patients were analyzed, the main outcomes being disease-free survival, overall survival, overall recurrence rate, and local recurrence rate 5 years after surgery. Results: Patients in both study groups completed the surgery successfully with no requirement for additional surgery. After mean 70 (7-83) months postoperative follow-up, the 5-year overall postoperative survival in the NOSES and CLS groups was 90.0% and 83.3%, respectively (P=0.455); disease free survival was 90.0% and 83.3%, respectively (P=0.455); overall recurrence rate 6.6% and 10.0%, respectively (P=0.625); and local recurrence rate both were 3.3% (P=0.990), respectively. None of these differences was statistically significant. Conclusions: NOSES and CLS have similar long-term efficacy, and NOSES deserves to be used in clinical practice.

[Comparison between laparoscopic-assisted natural orifice specimen extraction surgery and conventional laparoscopic surgery for left colorectal cancer: a randomized controlled study with 3-year follow-up results]

Objective: To evaluate the mid-term efficacy of laparoscopic-assisted natural orifice specimen extraction surgery (NOSES) colectomy using the Cai tube in the treatment of left colorectal cancer. Methods: A prospective randomized control trial (China Clinical Trials Registration Number: ChiCTR-OOR-15007060) was performed. Sixty patients with left colorectal cancer at Department of Gastrointestinal Surgery of Zhongshan Hospital from September 2015 to August 2017 were prospectively enrolled. Case inclusion criteria: (1) left colorectal adenocarcinoma (rectal cancer with distance ≥ 8 cm from tumor low margin to anal edge, sigmoid colon cancer, descending colon cancer and left transverse colon cancer) confirmed by preoperative pathology; (2) satisfactory conditions of conventional laparoscopic surgery; (3) maximum diameter of the tumor < 4.5 cm confirmed by preoperative abdominal and pelvic CT or MRI; (4) BMI < 30 kg/m². Case exclusion criteria: (1) benign lesions, mucinous adenocarcinoma, signet-ring cell carcinoma and other special pathological types of tumors confirmed by preoperative pathological examination; (2) multiple or recurrent cancers; (3) with a history of neoadjuvant chemoradiotherapy; (4) obvious regional infiltration or distant metastasis indicated by preoperative imaging examination; (5) intestinal obstruction, intestinal perforation, etc. Participants were randomly assigned to NOSES group (using the Cai tube) and conventional laparoscopy (CL) group by random number table method. Clinical data between two groups were compared and analyzed, including perioperative conditions, tumor exfoliation cell detection and bacterial culture results of intraperitoneal lavage fluid, postoperative complications (Clavien-Dindo grading), postoperative pain [visual simulation scoring (VAS) assessment], anal function (Kirwan anal function grading assessment), and postoperative 3-year disease-free survival (DFS), overall survival (OS), overall recurrence rate, and local recurrence rate. Results: A total of 60 patients were enrolled, with 30 in the NOSES group and 30 in the CL group. All the patients in the NOSES group successfully completed operation with Cai tube. Baseline data between the two groups were not significantly different (all P>0.05). There were no statistically significant differences between two groups in conversion rate to open surgery, number of lymph node harivested, proximal and distal resection margin of tumor, negative rate of circumferential margin, operation time, blood loss, inflammatory indexes, postoperative anal function, postoperative hospital stay, hospitalization cost, morbidity of postoperative complications (Clavien-Dindo grade II or above) (all P>0.05). Compared to the CL group, the NOSES group had lower maximum postoperative VAS score (2.5±0.3 vs. 5.1±0.4, t=3.187, P<0.01), and fewer use of additional postoperative analgesia [6.7% (2/30) vs. 33.3% (10/30),χ²=6.670, P=0.02]. The postoperative time to gas passage was shorter in the NOSES group [(2.2±1.4) days vs. (3.1±1.2) days,P=0.026]. No tumor cells and bacterial contamination were found in abdominal lavage fluid before and after operation in either group. The anal function at postoperative 3-month of all the patients in the NOSES group was Kirwan grade I to II, while in the CL group, anal function of 2 cases (6.7%) was Kirwan grade III, and of 28 cases was also Kirwan grade I to II, whose difference was not statistically significant (P>0.05). In the NOSES group and the CL group, 3-year DFS was 96.7% and 83.3% (P=0.090), OS was 100% and 90% (P=0.096), overall recurrence rate was 3.3% and 10.0% (P=0.166), and local recurrence rate was 3.3% and 3.3% (P=0.999), respectively, whose differences were not statistically significant (all P>0.05). Conclusions: In the treatment of left colorectal cancer, compared with conventional laparoscopic colectomy, NOSES colectomy using Cai tube exhibits less scar, less postoperative pain, shorter recovery of gastrointestinal function, and similar mid-term outcomes. Given proper surgical indications, the surgical procedure is safe and feasible.

[Systematic review on the reform of disease prevention and control system in China]

Objective: To systematically understand the reform progress of disease prevention and control system in China. Methods: The literature regarding the reform of China's disease prevention and control system was searched by using the keywords including disease prevention and control, center for disease prevention and control (CDC), disease control, reform, and system from 2003 to 2020 in China CNKI, Wanfang Data knowledge service platform, VIP information and China biomedical literature database. The language is limited to Chinese. A total of 25 studies were included to analyze the information about the organizational structure, functional orientation, financing mechanism and personnel system of China's disease prevention and control system. Results: The 25 studies described the specific changes and reform suggestions of China's disease prevention and control system, including key policies (7 studies), organizational structure transformation (4 studies), institutional function transformation (7 studies), financing mechanism transformation (5 studies), personnel system reform (2 studies), and performance-based salary system reform (4 studies). Meanwhile, the reform suggestions were concluded at the top-level design system reform (two aspects), organization structure (three aspects), functioning (four aspects), and personnel guarantee mechanism (three aspects). Conclusions: This study indicates that there is a lack of empirical evidence regarding specific reform effects and content analysis at the micro level of disease prevention and control system in China. Future study should strengthen the rigorousness of study design and focus on the quantitative impacts of reform implementation in China.

[Experimental study on the effect of three-dimensional porous structures on the vascularization rate of artificial dermis]

Objective: To explore the effects of orienting three-dimensional porous network (type A) and honeycomb briquette-shaped vertically penetrating three-dimensional porous network (type B) on the vascularization rate of artificial dermis. Methods: The experimental research method was used. The artificial dermis was composed of a double layer of silicone layer and scaffold layer. Based on the difference of scaffold layer, they were divided into type A and type B artificial dermis (type A dermis and type B dermis, for short) containing type A and type B structure, respectively. The type A and type B structures were prepared by gradient freeze-drying technique and physical pore-making technique, respectively. The micro-morphology of two kinds of dermis scaffold was observed by scanning electron microscopy. The porosity of two kinds of dermis scaffold was measured by the Pyrex method. According to the method of national medical industry standard, the hydroxyproline content in degradation liquids and their residues in two kind of dermis were determined after degradation at 4, 8, 13, and 24 h, reflecting the degradation rates of two kinds of dermis. According to the random number table, L929 cells were divided into type A dermis group, type B dermis group, negative control group, and positive control group. The positive control group was added with minimum essential medium (MEM) containing 5% dimethyl sulfoxide, The negative control group was added with high-density polyethylene extract, and the other two groups were added with the corresponding extract. At 24 hours after culture, the growth rate of L929 cells was detected by methyl thiazolyl tetrazolium, and the cytotoxicity was graded. L929 cells and human umbilical vein endothelial cells (HUVECs) were inoculated into pore plates with two kinds of dermis preinstalled. On 1, 4, 7, and 14 d after inoculating, the adhesion and growth of L929 cells on the surfaces of the two kinds of scaffolds were detected by immunofluorescence method. On 7 d after inoculating, the migration of the above two kinds of cells into the two kinds of dermal scaffolds was detected by immunofluorescence and hematoxylin-eosin (HE) staining. Three full-thickness skin defect wounds of 5.0 cm×5.0 cm were created on both sides of the back of three 6-month-old healthy male Ba-Ma mini pigs. According to the random number table, six columns of wounds were divided into type A dermis two-step method group, type B dermis two-step method group, and type B dermis one-step method group. The wounds in type A dermis two-step method group and type B dermis two-step method group were transplanted with type A or type B dermis respectively before, and with autologous split-thickness skin grafting later. The wounds in type B dermis one-step method group were transplanted in a synchronous procedure including type B dermis (without silicone layer) and autologous skin grafting simultaneously. The bleeding, exudation, and infection of the wounds on the back in type A dermis two-step method group and type B dermis two-step method group on the 7th day after the second transplantation and in type B dermis one-step method group on the 14th day after the first transplantation were generally observed. The area of autologous skin graft was measured by the transparent film grid method, and the survival rate of autologous skin was calculated. On 4, 7, and 14 d after the first transplantation, the inflammatory cells, fibroblasts (Fbs), and capillary infiltration into the scaffolds of the three groups were detected by HE staining. On 7, 14 d after the first transplantation, the vascularization of the scaffolds was further observed by immunohistochemistry. On 28, 90 d after the first operation, the degradation of the scaffolds of type A dermis and type B dermis was observed by HE staining. Data were statistically analyzed with one-way analysis of variance, independent sample t test, and Bonferroni correction. Results: A large number of round and oval micropores were evenly distributed on the surface of type A scaffold, and the cylindrical hole walls could be observed arranging in a parallel direction in the longitudinal section. The honeycomb briquette-shaped penetrating macropores on the surface of type B scaffold were arranged in an orderly matrix. The pore walls of the honeycomb briquette-shaped penetrating macropores were connected by micropores to form a network structure. The porosity of type A dermis was (93.21±0.72)%, which was similar to (95.88±1.00)% of type B dermis (t=4.653, P>0.05). The degradation rates of type A dermis at 4, 8, 13, and 24 h were similar to those of type B dermis at the corresponding time point (t=0.232, 0.856, 0.258, 7.716, P>0.05). At 24 h after culture, the proliferation rates of L929 cells in the type A dermis group, type B dermis group, and negative control group were significantly higher than those of the positive control group (t=2 393.46, 2 538.27, 1 077.77, P<0.01). The cytotoxicity rating of cells in positive control group was grade 4, while that of the other three groups was grade zero. On 1, 4, 7, and 14 d after inoculation, both L929 cells and HUVECs proliferated in a time-dependent manner in two kinds of dermal scaffolds. The adhesion growth and proliferation rate of the two kinds of cells on the surface of type B dermis was higher than that of type A dermis. On 7 d after inoculation, both L929 cells and HUVECs covered the surface of type B dermis and migrated into one side of the silicone layer. However, the above two kinds of cells migrated slowly into type A dermis, and only a few cells were found on one side of the silicone layer. There was no bleeding, exudation, or infection in the wounds repaired by type A and type B dermis. The survival rate of autologous skin grafting of 6 wounds in each group was 100%. On 4, 7, and 14 d after the first operation, inflammatory cells, Fbs, and capillaries gradually infiltrated into the scaffold layer, and the cell infiltration rate from high to low was type B dermis one-step method group, type B dermis two-step method group, and type A dermis two-step method group. The scaffold in wound in the type B dermis one-step method group gradually collapsed on 28 d after the first operation, and completely degraded in 3 months after the first operation. The scaffold degradation rate of type A dermis two-step method group was similar to that mentioned above. Conclusions: The honeycomb briquette-shaped vertically penetrating three-dimensional porous network structure of type B scaffold can accelerate its vascularization process, which is beneficial to autogenous split-thickness skin in one-step procedure to repair full-thickness skin defects wound in Ba-Ma mini pigs. Compared with the "two-step method" of staged transplantation of type A scaffold and autologous split-thickness skin, and one-step transplantation has equal efficacy and can provide a better choice for wound treatment.

[Research progress on building of disease control and prevention system of the international experience]

Through literature search in regular database and official websites of relevant countries, this paper combs and summarizes the main characteristics of disease prevention and control systems in five countries, the United States, Germany, South Korea, Australia and Japan, and the European Union at key levels including legal construction, organizational structure, financing, personnel construction and international cooperation, in order to provide decision support for the construction of disease prevention and control system in China in the future.

[Policy analysis of disease control and prevention system in China from the perspective of policy instruments from 2000 to 2020]

Objective: To analyze the related polities about disease control and prevention system in China from 2000 to 2020, and to provide implication for the policy formulation of disease control and prevention system in the future. Methods: Policy documents were searched in the official websites of relevant government departments including the State Council, National Health Commission, National Development and Reform Commission, Ministry of Human Resources and Social Security, and Ministry of Finance by using the keywords related to disease control and prevention from 2000 to 2020. Thematic framework and content analysis were performed to analyze the eligible policy documents based on the theory of policy instruments. Results: A total of 37 policy documents were included in this study. The application of single policy instrument was common (81.1%), of which the capacity building instrument was the most frequently used (32.4%), followed by mandate instrument (21.6%) and inducement instrument (13.5%), while system-changing instrument (8.1%) and symbolic and hortatory instrument were less used (5.4%). The main policy themes were personnel system (15.2%) and system construction (15.2%), followed by personnel development (13.0%) and information construction (2.2%). Conclusion: In the policy formulation process, the government should strengthen the comprehensive application of multiple policy instruments. Particularly about the inducement instrument and symbolic and hortatory instrument to further stimulate the internal motivation of disease control and prevention system and institutions in China.

[Changes of the number of disease control and prevention staffs at provincial level in China from 2002 to 2018: an interrupted time series analysis]

Objective: To analyze the change of the number of staff at the provincial center for disease control and prevention (CDC) in China before and after the new health care reform. Methods: The data was from publicly reported health statistics yearbooks from 2002 to 2018. Descriptive analysis and interrupted time series analysis (ITS) were conducted in Stata/SE 15. Results: The decreasing trend of total number and average number of CDC staff per ten thousand people further exacerbated in the eastern and central areas after the new health care reform, while the total number of CDC staff in the western area changed from a decreasing trend to an increasing tend and the decreasing trend of average number of CDC staff per ten thousand people slowed down. After controlling the provincial and time fixed effects, the ITS analysis showed that before the reform, the number of CDC staff in central area showed a decreasing trend (P=0.012). After the reform, no statistically significant changes were observed in the number of CDC staff in the eastern, central and western areas increased instantaneously (P>0.05), and the decreasing trend (slope) of the number of CDC staff in the eastern and central areas further increased. The number of CDC staff in the western area changed to an increasing trend (P>0.05). Conclusion: After the new health care reform, the total number and average number of CDC staff at the provincial level have not improved, therefore targeted reform strategies are needed to reverse the continuous reduction of CDC staff and reflect regional differences in the future.

[Analysis of sonographic characteristics of thyroid nodules diagnosed as false positive or negative results in shear wave elastography]

Objective:In order to improve diagnostic accuracy, we study the characteristics of two dimensional ultrasound and shear wave elastography in the diagnosis of false negative or false positive thyroid nodules by shear wave elastography.Method:One hundred and eighty-nine nodules in 189 consecutive patients who had been determined by surgical operation and pathology. Conventional ultrasound features and SWE elasticity imaging characteristics and properties of the final postoperative pathology were recorded. A comparative study between true and false results of quantitative SWE elasticity imaging, and the corresponding conventional ultrasound nodule characteristics were compared.Result:Postoperative pathology showed 189 nodules, 74(39.2%) were benign and 115(60.8%) were malignant. The sensitivity, specificity of conventional ultrasound in the diagnosis of thyroid nodules were 56.5% and 81.1% respectively, and those of SWE were 60.9% and 85.1%. The false positive rate of shear wave elastography in diagnosing benign nodules and the false negative rate of malignant nodules were 14.9% and 39.1%, respectively. The false negative rate was higher than the false positive rate. A vertical growth (P< 0.01) and smaller diameter of the masses were significantly associated with false SWE findings (P< 0.01).Conclusion:The SWE imaging has important significance for differentiating benign and malignant thyroid nodules, but false results are inevitable, which requires clinicians conjunction with other test results to prevent errors judgment when reviewing the SWE imaging.

[Role and clinical significance of Th17/Treg balance in patients with severe exacerbation of hepatitis B]

OBJECTIVE

To investigate the role of Th17/Treg balance in immune mechanism in severe exacerbation of hepatitis B.

METHODS

The clinical data of 41 patients with chronic hepatitis B were collected, and according to the conditions during hospitalization, these patients were divided into exacerbation group (19 patients) and improvement group (22 patients). On admission, at weeks 1 and 2 of treatment, and at the end of treatment, flow cytometry was used to measure the frequencies of Th17 and Treg cells in peripheral blood, and enzyme-linked immunosorbent assay was used to determine the serum levels of interleukin-17 (IL-17), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β). The dynamic changes in the frequencies of Th17 and Treg cells were compared between the two groups, and the correlation between clinical indices for hepatitis and cytokines was analyzed. The t-test was used for comparison between groups, a one-way analysis of variance was used for comparison within one group across different time points, and Pearson correlation analysis was performed.

RESULTS

With disease progression, the exacerbation group showed an increase in the frequency of Th17 cells and a relatively low frequency of Treg cells; compared with the improvement group, the exacerbation group had a higher frequency of Th17 cells and a lower frequency of Treg cells. Th17/Treg ratio gradually increased with exacerbation and decreased with improvement in conditions; in the exacerbation group and the improvement group, Th17/Treg ratio was positively correlated with total bilirubin and negatively correlated with prothrombin activity. In the exacerbation group and the improvement group, Th17 cells were positively correlated with IL-17, and Treg cells were positively correlated with IL-10 and TGF-β.

CONCLUSION

Th17 and Treg cells play important roles in severe exacerbation of hepatitis B, and Th17/Treg ratio may be used as an immunobiological marker for the judgment of severity during severe exacerbation of hepatitis B.

Investigation on the co-infections of Toxoplasma gondii with PRRSV, CSFV or PCV-2 in swine in part of China

The objective of the present investigation was to estimate the prevalence of Toxoplasma gondii infection and co-infection with porcine reproductive and respiratory syndrome virus (PRRSV), classical swine fever virus (CSFV) and porcine circovirus type 2 (PCV-2) in pigs in China. A total of 372 tissues or serum samples collected from pigs distributed in 9 provinces/municipalities of China during the period from February 2011 to November 2012 were assayed for T. gondii antigens and antibodies using enzyme linked immunosorbent assay (ELISA) technique, while the PCR was designed for the detection of the PRRSV, CSFV and PCV-2, respectively. The total positive rate of T. gondii, PRSSV, CSFV and PCV-2 was 9.14% (34/372), 50.00% (186/372), 37.10% (138/372) and 3.23% (12/372), respectively. Among the 34 T. gondii positive samples, 26 samples were simultaneously infected with T. gondii and viruses, while the remaining eight samples were infected with T. gondii alone. In addition, the co-infection rate of T. gondii with PRSSV, T. gondii with PRSSV and CSFV, T. gondii with PRSSV and PCV-2, T. gondii with CSFV and PCV-2, T. gondii with PRSSV, CSFV and PCV-2 was 1.61% (6/372), 4.03% (15/372), 0.27% (1/372), 0.27% (1/372) and 0.81% (3/372), respectively. The results of the present survey revealed that PRRSV and CSFV were the common pathogens co-existing with porcine toxoplasmosis in China, and both of them could increase the chances of T. gondii infection in pig. This is the first report of T. gondii co-infections with viruses in pigs. It is very important to understand the interactions of parasite and virus, and can be used as reference data for the control and prevention of co-infections of T. gondii and viruses in pigs.

Co-existence of multiple strains of porcine circovirus type 2 in the same pig from China

Pigs are often co-infected by different viral strains from the same virus. Up to now, there are few reports about co-existence of different porcine circovirus type 2 (PCV2) strains in China. The aim of this study was to evaluate it in Chinese swine herds. 118 PCV2 positive DNAs isolated from diseased pigs identified by classic PCR were re-detected using a modified differential PCR assay. The results indicated that co-existence rates of PCV2 were 32.2% (38/118) in diseased pigs and 0% (0/41) in asymptomatic pigs. Four PCV2 complete genomes were cloned from two co-infected samples and their nucleotide (nt) identities were 95%-97.3%. The phylogenetic analysis showed that four PCV2 strains were divided into different genotypes, PCV2a, PCV2b, PCV2d and PCV2e, respectively. In addition, co-existence were not detected in 41 serum samples from healthy pigs but PCV2 single infection (31.7%, 13/41) existed. These data revealed that the co-existence of different strains of PCV2 might contribute to the development of more severe clinical symptoms for pigs. This is the first report confirming the co-existence of different PCV2 strains in Chinese swine herds. Meanwhile, this study could help us to understand new infection and prevalence forms of PCV2 clinically.

The RNA profile of porcine parvovirus 4, a boca-like virus, is unique among the parvoviruses

PPV4 transcribes its genome from a single promoter, and the RNAs are generated via alternate splicing coupled with alternate polyadenylation, a strategy similar to that of the bocaviruses; however, several differences were detected. The PPV4 ORF1 codes for four NS proteins, while the bocavirus ORF1 codes for 1-3 NS proteins. Whereas the VP1/VP2 capsid proteins of bocavirus are encoded by a single RNA, VP1 and VP2 of PPV4 are encoded by two separate RNAs. While ORF3 of PPV4 encodes two NP proteins, ORF3 of bocavirus codes for only one NP polypeptide. Taken together, PPV4 is unique among the parvoviruses.

[Study on liver injury of Oncomelania hupensis caused by Eomecon chinanthe sanguinarine]

OBJECTIVE

To analyze the effects of Eomecon chinanthe sanguinarine (SAN) on glucogen, enzyme activity and lipid peroxidation of Oncomelania hupensis liver so as to explore the mechanism of SAN against Oncomelania hupensis.

METHODS

SAN was extracted and purified from the dry powder of Eomecon chionantha. Oncomelania hupensis were immersed in 5 mg/L sanguinarine (50 Oncomelania hupensis per 500 ml solution) or clean water at 25 degrees C for 36 h, the livers were isolated from live snails. Total glucogen content, malondialdehyde (MDA) level, activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase (SOD), peroxidase (POD) were determined respectively and the data were analyzed by independent t test.

RESULTS

The glucogen content of snail livers in the SAN group and the control group were (12.151 +/- 0.204) and (18.113 +/- 0.163) mg/g respectively, the difference between the two groups was significant (P < 0.05); the MDA levels of the two groups were (5.298 +/- 0.441) and (4.351 +/- 0.197) nmol/mgprot respectively, and the difference was not significant (P > 0.05); the activities of ALT, AST, ACP, AKP, SOD in the SAN group were (2.760 +/- 0.076) U/mgprot, (68.723 +/- 2.295) U/mgprot, (407.949 +/-19.868) U/gprot, (191.287 +/- 0.771) U/ gprot and (48.452 +/- 0.193) U/mgprot respectively, the activities of these enzymes in the control group were (1.104 +/- 0.000) U/mgprot, (49.448 +/- 1.626) U/mgprot, (344.475 +/- 30.186) U/gprot, (121.905 +/- 3.127) U/gprot and (38.814 +/- 2.765) U/mgprot respectively, the activities of ALT, AST, ACP, AKP and SOD were significantly increased after immersed in 5 mg/L SAN for 36 h, the differences were significant (All P values < 0.05); yet the difference of POD between the SAN group [(22.170 +/- 0.018) U/mgprot] and the control group [(21.747 +/- 0.264) U/mgprot] was not significant (P > 0.05).

CONCLUSION

SAN can destroy liver functions of Oncomelania hupensis through decreasing glucogen content and changing activities of some important enzymes in snail liver.

Detection of a novel porcine parvovirus, PPV4, in Chinese swine herds

To determine whether the novel porcine parvovirus type 4 (PPV4) recently reported in America is prevalent in China, a set of specific primers was designed and used for molecular survey of PPV4 among the clinical samples collected from various provinces of China between 2006 and 2010. The results showed that PPV4 is present in Chinese swine herds at a rate of 2.09% (12/573) among the clinical samples examined and 0.76% (1/132) among the samples taken from healthy animals. We also noted that PPV4 was not detected in samples taken prior to 2009. Analysis of the coding sequences showed that the Chinese and American PPV4 genome sequences are closely related with greater than 99% nucleotide sequence identity. Similar to a previous study, viral genomes in head-to-tail configuration of various lengths of the non-coding region were detected. Our findings confirmed that PPV4 is a unique recently discovered virus in pigs. Phylogenetically, PPV4 is most closely related to bovine parvovirus 2 (BPV2, which is not a Bocavirus and is not assigned to any Parvovirinae genus) and shares limited ORF1 (33.6%) and ORF2 (24.5%) amino acid identity. With respect to genome structure and organization, PPV4 encodes an ORF3 in the middle of the viral genome that resembles the Bocavirus genus. However, the PPV4 ORF3 encoded protein shares minimal amino acid identity with the ORF3 encoded proteins of the Bocavirus genus.

[Identification of porcine reproductive and respiratory syndrome virus regulation sequence in 3'-untranslated region]

Based on our established infectious clone of PRRSV, designated as pCBC2, a series of mutagenesis of 3'-untranslated region (3'-UTR) at primary structure and secondary structure level were constructed. Then the full length mutant clones were transfected into MARC-145 cells, from which the influences of the discrete 3'-UTR mutation on PRRSV replication and transcription were analyzed. The properties of the rescued mutant viruses were then further characterized by Northern Blot and plaque morphology analysis. Our results demonstrated that PRRSV could tolerate more than 41 nucleotides deletion and 23nt insertion in the 3'-UTR, however, minor changes in the conserved stem loop region destroyed virus infectivity. To sum up, the stem-loop structure was essential for virus viability, but 5' end of the 3'-UTR tolerates certain level of nucleotide deletion or insertion. This is the first report to define the essential sequence and secondary structure for PRRSV genome replication and it is useful for future research about the regulation element.

Altered p-JAK1 expression is associated with estrogen receptor status in breast infiltrating ductal carcinoma

The mammalian Janus kinase (JAK) family consists of four members, namely JAK1, JAK2, JAK3 and TYK2, which play a critical role in cytokine/growth factor signaling and is increasingly associated with human cancers. Aberrant activation of these non-receptor tyrosine kinases may contribute to carcinogenesis. Herein, we focused on exploring the potential role of p-JAK1 in breast cancer. The expression profiles of p-JAK1 were analyzed in 68 pairs of cancer and non-cancer breast tissues from the same infiltrating ductal carcinoma case by using immunoblotting technique. The results obtained were further correlated with clinicopathological characteristics. Intriguingly, p-JAK1 expression was decreased in 55.9% of breast cancer tissues as compared to the matched non-cancer tissues. Further immunohistochemistry study showed an intense p-JAK1 staining predominantly in adjacent normal breast tissues but not the matched cancer lesions. Decreased p-JAK1 expression in breast cancer tissues was significantly correlated with positive estrogen receptor (ER) status and increased tumor size (p=0.010 and 0.009). We also found that p-JAK1 expression was high in ERalpha-negative breast cancer cell lines but was low in ERalpha-positive breast cell lines. Transfection of ERalpha-positive MCF-7 cells with an ERalpha-specific siRNA upregulated the expression of p-JAK1. In summary, our results indicated that an altered p-JAK1 expression might be involved in the development of breast infiltrating ductal carcinoma in an ERalpha-related manner.

[Expression of truncated Toxoplasma gondii GRA8 in the prokaryotic expression plasmids]

OBJECTIVE

To construct the prokaryotic recombinant expression plasmids of Toxoplasma gondii GRA8 and analyze their expression in E. coli containing the prokaryotic recombinant plasmids.

METHODS

The full gene and its truncated fragment of GRA8 were amplified by PCR from T. gondii genomic DNA, and cloned into pMD18-T vector. The right genes in positive clones sequenced with ABI PRISMTM 377XL DNA Sequencer were digested with restrictive endonucleases and subcloned into pGEX-4T-2. The recombinant plasmids were transformed into E. coli JM109. The recombinant clones were characterized by PCR and digested with restriction endonucleases. Positive clones were induced with IPTG to express target protein and characterized by SDS-PAGE. The recombinant protein was purified from E. coli lysate by affinity chromatography and SDS-PAGE. The immunological activity of this protein was analyzed by Western blotting.

RESULTS

The gene fragments encoding GRA8 were amplified by PCR from T. gondii genomic DNA. The inserts of GRA8 in positive clones were coincident with the original sequence of GRA8 gene from GenBank. The recombinant expression plasmids were constructed through subcloning the right inserts of GRA8 into pGEX-4T-2. The expression level of GRA8 from the recombinant expression plasmids in E. coli was low, and there was almost no full-length GRA8 expressed in E. coli. The purified protein reacted with the sera from rabbits infected with T. gondii RH strain.

CONCLUSION

The expression level of GRA8 from the recombinant expression plasmids in E. coli is low and the purified truncated GRA8 shows certain antigenicity.

Molecular cloning, expression and vaccination of a novel gene Sj-MA of Schistosoma japonicum

In order to obtain new gene and to develop the new vaccine candidate of immunoprotection against Schistosoma japonicum (Sj), Sj adult worm cDNA library was screened with anti-sera to soluble male adult worm antigen and resulted in the discovery of a novel gene designated as Sj-MA. Sequence analysis showed that Sj-MA as a complete cDNA contains one open reading frame. It was deduced to contain 249 amino acid residues and encode a 28.8 kD soluble protein with plenty of phosphorylation sites, supposing its action in signal transduction. Furthermore, Sj-MA cDNA was cloned into a prokaryotic expression vector pGEX-5X to construct the recombinant plasmid which was transformed and highly expressed in E. coli as a 54.8 kD glutathione-S-transferase (GST) fusion protein. The fusion protein rSj-MA/GST could be recognized with both anti-male adult worm sera and anti-GST sera in Western blotting. Mice vaccinated with the fusion protein revealed significant worm reduction rate of 34.29% (P<0.001), compared with the control groups. Taken together, the novel gene Sj-MA can be expressed in E. coli as a fusion protein that can elicit immunity against Schistosoma japonicum, suggesting its potential as a new vaccine candidate.

Arsenite-induced nitric oxide generation is cell cycle-dependent and aberrant in NBS cells

Exposure to arsenic has been reported to cause DNA damage and eventually the occurrence of bladder, lung and skin cancers. A previous report has demonstrated that arsenite-induced phosphorylation of Mre11, a protein involved in the repair of DNA double strand breaks (DSBs), is M phase-dependent and requires the Nijmegen breakage syndrome (NBS) protein, NBS1 [DNA Repair 1 (2002) 137]. Furthermore, arsenite treatment arrests cells at the M phase and the cells eventually go through apoptosis [Biochemical Pharmacology 60 (2000) 771]. Here we demonstrate that arsenite treatment enhances the generation of nitric oxide (NO), and that the enhanced NO generation is dominant at the G2/M phase. Arsenite-induced NO generation is impaired in DSB repair-defective NBS cells, but not in NBS1-reconstituted NBS cells, suggesting NBS1 is required for effective NO generation. In summary, our study showed, for the first time, that arsenite-induced NO generation is cell-cycle- and NBS1-dependent.

Functional link between ataxia-telangiectasia and Nijmegen breakage syndrome gene products

Ataxia-telangiectasia (A-T) and Nijmegen breakage syndrome (NBS) are recessive genetic disorders with susceptibility to cancer and similar cellular phenotypes. The protein product of the gene responsible for A-T, designated ATM, is a member of a family of kinases characterized by a carboxy-terminal phosphatidylinositol 3-kinase-like domain. The NBS1 protein is specifically mutated in patients with Nijmegen breakage syndrome and forms a complex with the DNA repair proteins Rad50 and Mrel1. Here we show that phosphorylation of NBS1, induced by ionizing radiation, requires catalytically active ATM. Complexes containing ATM and NBS1 exist in vivo in both untreated cells and cells treated with ionizing radiation. We have identified two residues of NBS1, Ser 278 and Ser 343 that are phosphorylated in vitro by ATM and whose modification in vivo is essential for the cellular response to DNA damage. This response includes S-phase checkpoint activation, formation of the NBS1/Mrel1/Rad50 nuclear foci and rescue of hypersensitivity to ionizing radiation. Together, these results demonstrate a biochemical link between cell-cycle checkpoints activated by DNA damage and DNA repair in two genetic diseases with overlapping phenotypes.

BRCA2 is required for ionizing radiation-induced assembly of Rad51 complex in vivo

Mutations in BRCA1 and BRCA2 account for the majority of familial breast cancers. Cells with mutated BRCA1 or BRCA2 are hypersensitive to ionizing radiation (IR) and exhibit defective DNA repair. Both BRCA1 and BRCA2 have been reported to bind Rad51, a protein essential for homologous recombination and the recombinational repair of DNA double-strand breaks. In normal cells, a redistribution of Rad51 protein, manifested as formation of Rad51 nuclear foci, is seen upon IR treatment. Here we demonstrate that IR-induced Rad51 foci formation is aberrant in BRCA2- but not BRCA1-deficient tumor cells. In Capan-1 cells, which do not express functional BRCA2, there was little Rad51 foci formation in response to a wide range of radiation dosages. Moreover, forced expression of a fusion protein containing green fluorescent protein and the first Rad51-binding BRC repeat of BRCA2 in cells with wild-type BRCA2 rendered them hypersensitive to IR and cisplatin and compromised IR-induced Rad51 foci formation. In HCC1937 cells, which harbor mutation of BRCA1, IR-induced Rad51 foci were readily detected. This study suggests a requirement of BRCA2 protein for the IR-induced assembly of Rad51 complex in vivo.

Radiation-induced assembly of Rad51 and Rad52 recombination complex requires ATM and c-Abl

Cells from individuals with the recessive cancer-prone disorder ataxia telangiectasia (A-T) are hypersensitive to ionizing radiation (I-R). ATM (mutated in A-T) is a protein kinase whose activity is stimulated by I-R. c-Abl, a nonreceptor tyrosine kinase, interacts with ATM and is activated by ATM following I-R. Rad51 is a homologue of bacterial RecA protein required for DNA recombination and repair. Here we demonstrate that there is an I-R-induced Rad51 tyrosine phosphorylation, and this induction is dependent on both ATM and c-Abl. ATM, c-Abl, and Rad51 can be co-immunoprecipitated from cell extracts. Consistent with the physical interaction, c-Abl phosphorylates Rad51 in vitro and in vivo. In assays using purified components, phosphorylation of Rad51 by c-Abl enhances complex formation between Rad51 and Rad52, which cooperates with Rad51 in recombination and repair. After I-R, an increase in association between Rad51 and Rad52 occurs in wild-type cells but not in cells with mutations that compromise ATM or c-Abl. Our data suggest signaling mediated through ATM, and c-Abl is required for the correct post-translational modification of Rad51, which is critical for the assembly of Rad51 repair protein complex following I-R.

Cloning and functional studies of a novel gene aberrantly expressed in RB-deficient embryos

The tumor suppressor RB regulates diverse cellular processes such as G1/S transition, cell differentiation, and cell survival. Indeed, Rb-knockout mice exhibit phenotypes including ectopic mitosis, defective differentiation, and extensive apoptosis in the neurons. Using differential display, a novel gene, Rig-1, was isolated based on its elevated expression in the hindbrain and spinal cord of Rb-knockout embryos. The longest open reading frame of Rig-1 encoded a polypeptide that consists of a putative extracellular segment with five immunoglobulin-like domains and three fibronectin III-like domains, a putative transmembrane domain, and a distinct intracellular segment. The Rig-1 sequence was 40% identical to the recently identified roundabout protein. Consistent with the predicted transmembrane nature of the protein, Rig-1 protein was present in the membranous fraction. Antisera raised against the putative extracellular and intracellular segments of Rig-1 reacted with an approximately 210-kDa protein in mouse embryonic CNS. Rig-1 mRNA was transiently expressed in the embryonic hindbrain and spinal cord. Elevated levels of Rig-1 mRNA and protein were found in Rb-/- embryos. Ectopic expression of a transmembrane form of Rig-1, but not the secreted form, promoted neuronal cell entrance to S phase and repressed the expression of a marker of differentiated neuron, Talpha1 tubulin. Thus Rig-1, a possible distant relative of roundabout, may mediate some of the pleiotropic roles of RB in the developing neurons.

Nuclease activities in a complex of human recombination and DNA repair factors Rad50, Mre11, and p95

Genetic studies in yeast have indicated a role of the RAD50 and MRE11 genes in homologous recombination, telomere length maintenance, and DNA repair processes. Here, we purify from nuclear extract of Raji cells a complex consisting of human Rad50, Mre11, and another protein factor with a size of about 95 kDa (p95), which is likely to be Nibrin, the protein encoded by the gene mutated in Nijmegen breakage syndrome. We show that the Rad50-Mre11-p95 complex possesses manganese-dependent single-stranded DNA endonuclease and 3' to 5' exonuclease activities. These nuclease activities are likely to be important for recombination, repair, and genomic stability.

Dual roles of the retinoblastoma protein in cell cycle regulation and neuron differentiation

To assess the functions of the retinoblastoma protein (RB) during normal development, we have analyzed mouse embryos that lack a functional copy of the retinoblastoma gene (genotype: Rb-1 delta 20/Rb-1 delta 20). Our findings demonstrate that RB plays an important role in the regulation of the neuronal cell cycle. In mutant embryos, dividing cells are found well outside of the normal neurogenic regions in both the central and peripheral nervous systems. In addition to abnormal cell cycle regulation, however, the mutant embryos show two less expected phenotypes. First, many of the ectopically dividing cells die by apoptosis shortly after their entrance into S phase. In sensory ganglia, most nerve cells die by this process, beginning at about the same time as normal target-related neuronal death. Second, although the expression of certain differentiation markers such as N-CAM and Brn-3.0 appears to be near normal, nerve cells, especially in sensory ganglia, do not mature properly. Their morphology is stunted and expression of neuronal beta II tubulin is greatly reduced. Preferential reduction in the expression of TrkA, TrkB, and the low-affinity neurotrophin receptor p75LNGFR may be relevant to neuronal cell death and lack of neuronal differentiation seen in the mutant embryos. Primary cultures of dorsal root and trigeminal ganglion cells from later stage mutant embryos reveal a decrease in neuronal cell survival and in neurite outgrowth even in the presence of the appropriate neurotrophins. Taken together, these results suggest that the p110RB protein not only regulates progression through the cell cycle but is also important for cell survival and differentiation.

Synthesis of 3,4-13C2-steroids

A-ring enollactones la, lb, or 9 derived from 4-cholesten-3-one, testosterone benzoate or 3-oxo-4-estren-17 beta-yl benzoate were condensed with [1,2-13C2]acetyl chloride to give intermediates 2a, 2b, or 10. 2a and 2b were cyclized by acid or base to give 3,4 13c-labeled 4-cholesten-3-one and testosterone, respectively. [3,4-13c2 14-Cholesten-3-one was converted via reduction of its trimethylsilyl enol ether to [3,4-13C2] cholesterol. Acetyl enollactone 10 was cyclized in acetic acid to [3,4-13c2] 3-oxo-4-estren-17beta-yl benzoate followed by aromatization and hydrolysis to produce ]3,4-13c2] estradiol-17 beta. Alternatively, cyclization of 10 with base afforded [3,4-13c2-oxo-4-estren-17 beta-ol directly, which was then oxidized and aromatized to yield ]3,4-13c2] estrone. Ozonolysis of progesterone, conversion to the diketal ester 16 and acylation followed by acid hydrolysis furnished [3,4-13c2] progesterone.

Synthesis and activity of (R)-(-)-m-trimethylacetoxy-alpha-[(methylamino)methyl]benzyl alcohol hydrochloride: a prodrug form of (R)-(-)-phenylephrine

Optically pure (R)-(-)-m-trimethylacetoxy-alpha-[(methylamino)methyl]benzyl alcohol hydrochloride was synthesized by the following sequence: (R)-(-)-phenylephrine was condensed with acetone in the presence of calcium carbide to give an oxazolidine derivative and then treated with thallous ethoxide in ether followed by trimethylacetyl chloride to yield the phenolic ester. Finally, the oxazolidine ring was cleaved by one equivalent of hydrogen chloride in ethanol. Condensation of phenylephrine with benzaldehyde, with or without solvents, gave either 1,1,2-trimethyl-4,6-dihydroxy-1,2,3,4-tetrahydroisoquinoline or a mixture of side-chain oxazolidine and the tetrahydroisoquinoline. Condensation of epinephrine with opianic acid in pyridine also gave a tetrahydroisoquinoline only. When applied on rabbit eyes, the prodrug (R)-(-)-m-trimethylacetoxy-alpha[(methylamino)methyl]benzyl alcohol hydrochloride exhibited an unexpected, three times higher mydriatic activity than the corresponding racemic prodrug and was 15 times more active than the parent, (R)-(-)-phenylephrine.