Artificial Intelligence in the Management of Intracranial Aneurysms: Current Status and Future Perspectives

Intracranial aneurysms with subarachnoid hemorrhage lead to high morbidity and mortality. It is of critical importance to detect aneurysms, identify risk factors of rupture, and predict treatment response of aneurysms to guide clinical interventions. Artificial intelligence has received worldwide attention for its impressive performance in image-based tasks. Artificial intelligence serves as an adjunct to physicians in a series of clinical settings, which substantially improves diagnostic accuracy while reducing physicians' workload. Computer-assisted diagnosis systems of aneurysms based on MRA and CTA using deep learning have been evaluated, and excellent performances have been reported. Artificial intelligence has also been used in automated morphologic calculation, rupture risk stratification, and outcomes prediction with the implementation of machine learning methods, which have exhibited incremental value. This review summarizes current advances of artificial intelligence in the management of aneurysms, including detection and prediction. The challenges and future directions of clinical implementations of artificial intelligence are briefly discussed.

Loss of IGF2R indicates a poor prognosis and promotes cell proliferation and tumorigenesis in bladder cancer via AKT signaling pathway

The insulin growth factor 2 receptor (IGF2R) belongs to insulin growth factor (IGF) pathway and has been proposed as the tumor suppressor in many cancers. However, its role in bladder cancer is unknown. In the current study, we reported that IGF2R expression was decreased in bladder cancer tissues (p<0.05). Immunohistochemistry (IHC) and Cox regression analysis showed that low IGF2R expression was significantly associated with more advanced histological grade; high clinical stage; lymph node metastasis and poorer overall survival for patients with bladder cancer. Moreover, silencing IGF2R promoted cell proliferation of bladder cancer cells in vitro and in vivo (p<0.05). Furthermore, knockdown IGF2R resulted in higher phosphorylation level of AKT. The findings of this study indicated that IGF2R played a tumor suppressor role in bladder cancer. Downregulation IGF2R may promote tumor growth by activating AKT signaling pathway. IGF2R could be considered as a promising candidate for novel biomarker and therapeutic target for human bladder cancer.

Open peroral endoscopic myotomy for the treatment of achalasia: a case series of 82 cases

During peroral endoscopic myotomy (POEM), creation of the tunnel is highly technically demanding and mucosal injury is one of the most common potential complications. We explored a method without a submucosal tunnel, which we call open peroral endoscopic myotomy (O-POEM). This study aimed to assess the feasibility and safety of O-POEM. O-POEM was performed on 82 patients with achalasia. Treatment success was defined as an Eckardt score of less than or equal to 3 after the myotomy. Adverse events including operative and postoperative adverse events were recorded. Treatment success and procedure-related adverse events were analyzed. After a median follow-up of 18 months (range: 6-26 months), the treatment success (Eckhart score ≤3) was achieved in 96.3% of cases (mean score pre- vs. post-treatment (7.4 vs. 1.8); P < 0.001) with a recurrence of 3 cases. Ten patients (12.2%) had adverse events consisting of 2 cases of mediastinitis, 1 case of post-O-POEM bleeding, 1 case of subcutaneous emphysema, 6 cases of pleural effusion. Two cases of mediastinitis required intraprocedural drainage, and other patients were managed by endoscopy and conservative medical treatment. There were no deaths. No patients required surgical conversion. Clinical reflux occurred in 15.9% of patients (13/82). O-POEM was reliable and effective for the treatment of achalasia. In addition, O-POEM might be a better option for patients with severe submucosal fibrosis.

SPOP suppresses osteosarcoma invasion via PI3K/AKT/NF-κB signaling pathway

OBJECTIVE

Speckle-type POZ protein (SPOP), is an E3 ubiquitin ligase adaptor that is frequently mutated in prostate and endometrial cancers. SPOP has been shown to be responsible for oncogene SRC-3 ubiquitination and proteolysis in prostate cancers.  However, whether SPOP plays a role in osteosarcoma (OS) is unknown. In this study, we investigated the inhibitory effect of SPOP on invasion and migration of OS cells.

PATIENTS AND METHODS

Real-time PCR and Western blot were used to detect the expression of SPOP in human OS samples and cell lines. Short hairpin RNA (shRNA) was used to silencing the expression of SPOP. Small scale Real-time PCR screen was used to identify the matrix metalloproteases (MMP) family members responsible for the phenotype caused by SPOP depletion. Matrigel-coated invasion chambers were used to detect the invasion ability of SPOP in OS cells.

RESULTS

We found that SPOP was down-regulated in clinic OS samples and cultured OS cells. Furthermore, we showed that silencing of SPOP promoted cell migratory and invasive ability of OS cells in vitro, whereas restored the expression of SPOP achieved the opposite effects. At the molecular level, we found that SPOP regulated the activity of "PI3K/Akt/NF-κB" signaling pathway in OS cells.

CONCLUSIONS

Our results suggested that down-regulation of SPOP promoted OS cells migratory and invasive ability via modulating the "PI3K/Akt/NF-κB" signaling pathway. Thus, SPOP could be a promising drug target for the treatment of OS invasion.

Machine learning algorithms can classify outdoor terrain types during running using accelerometry data

BACKGROUND

Running is a popular physical activity that benefits health; however, running surface characteristics may influence loading impact and injury risk. Machine learning algorithms could automatically identify running surface from wearable motion sensors to quantify running exposures, and perhaps loading and injury risk for a runner.

RESEARCH QUESTION

(1) How accurately can machine learning algorithms identify surface type from three-dimensional accelerometer sensors? (2) Does the sensor count (single or two-sensor setup) affect model accuracy?

METHODS

Twenty-nine healthy adults (23.3 ± 3.6 years, 1.8 ± 0.1 m, and 63.6 ± 8.5 kg) participated in this study. Participants ran on three different surfaces (concrete, synthetic, woodchip) while fit with two three-dimensional accelerometers (lower-back and right tibia). Summary features (n = 208) were extracted from the accelerometer signals. Feature-based Gradient Boosting (GB) and signal-based deep learning Convolutional Neural Network (CNN) models were developed. Models were trained on 90% of the data and tested on the remaining 10%. The process was repeated five times, with data randomly shuffled between train-test splits, to quantify model performance variability.

RESULTS

All models and configurations achieved greater than 90% average accuracy. The highest performing models were the two-sensor GB and tibia-sensor CNN (average accuracy of 97.0 ± 0.7 and 96.1 ± 2.6%, respectively).

SIGNIFICANCE

Machine learning algorithms trained on running data from a single- or dual-sensor accelerometer setup can accurately distinguish between surfaces types. Automatic identification of surfaces encountered during running activities could help runners and coaches better monitor training load, improve performance, and reduce injury rates.

MiR-19b Functions as a Potential Protector in Experimental Autoimmune Encephalomyelitis

BACKGROUND

MicroRNA-19b (miR-19b) is essential in determining oligodendroglia proliferation. Phosphatase and tensin homologue on chromosome 10 (PTEN) is considered the target of miR-19b and participates in oligodendrocyte differentiation and proliferation.

METHODS

Murine EAE was induced by myelin oligodendrocyte glycoprotein (MOG35- 55). For EAE reversal, artificially synthesized agomiR-19b was intravenous injected after immunization.

RESULTS

We found that the expression of miR-19b is significantly reduced in an experimental autoimmune encephalomyelitis (EAE) mouse model. This downregulation, which is associated with the neurological scores, can be dramatically ameliorated by agomiR-19b. Our results show that agomiR-19b increases the expression of myelin basic protein (MBP) and cyclic nucleotide phosphodiesterase (CNP), which are regularly utilized as molecular markers of oligodendrocytes. Furthermore, our study also revealed that miR-19b probably affects the expression of PTEN in the EAE model.

CONCLUSION

These results indicate that the restoration of miR-19b probably exerts its therapeutic effect by affecting PTEN in the pathogenesis of EAE.

Seven Novel and Three Known Mutations in FOXL2 in 10 Chinese Families with Blepharophimosis Syndrome

BACKGROUND

Blepharophimosis syndrome (BPES) is characterized by eyelid malformation with occasional premature ovarian failure. Mutations in FOXL2 underlie a fraction of BPES cases.

OBJECTIVE

We aimed to investigate the genetic basis of BPES in 26 Chinese families that included 78 patients.

METHODS

We performed ophthalmological examinations on each family member. We used Sanger sequencing to screen FOXL2 exons and their flanking sequences. We also performed bioinformatics studies, structural modeling and pathogenicity evaluations on all identified variations. Literature was reviewed and genotype-phenotype correlation analysis was performed.

RESULTS

The patients had typical manifestations of BPES. Ten mutations were identified in ten of the twenty-six families. Among these, seven were novel mutations. These included the six truncating mutations, p.Glu69*, p.Gly256Glyfs*14, p.Ala14Serfs*135, p.Pro333Profs*200, p.Pro290Leufs*70, and p.Pro157Profs*91, and one missense mutation, p.Tyr59Cys. The mutations were scattered within the gene, and no mutational hotspots were found. Genotype-phenotype correlation analysis showed that frameshift or nonsense mutations were correlated with type I BPES, while in-frame or missense mutations were associated with type II BPES.

CONCLUSION

We report the largest BPES cohort in China thus far as well as seven novel mutations in FOXL2. The identification of novel mutations has not only expanded the mutational spectrum of the gene (which is valuable for mutation detection-based screening) but also suggests that most mutations within the Chinese population may not have been characterized yet.

Notch Coordinates Periodontal Ligament Maturation through Regulating Lamin A

Tooth eruption is a continuous biological process with dynamic changes at cellular and tissue levels, particularly within the periodontal ligament (PDL). Occlusion completion is a significant physiological landmark of dentition establishment. However, the importance of the involvement of molecular networks engaging in occlusion establishment on the final PDL maturation is still largely unknown. In this study, using rat and mouse molar teeth and a human PDL cell line for RNAseq and proteomic analysis, we systematically screened the key molecular links in regulating PDL maturation before and after occlusion establishment. We discovered Notch, a key molecular pathway in regulating stem cell fate and differentiation, is a major player in the event. Intercepting the Notch pathway by deleting its key canonical transcriptional factor, RBP-Jkappa, using a conditional knockout strategy in the mice delayed PDL maturation. We also identified that Lamin A, a cell nuclear lamina member, is a unique marker of PDL maturation, and its expression is under the control of Notch signaling. Our study therefore provides a deep insight of how PDL maturation is regulated at the molecular level, and we expect the outcomes to be applied for a better understanding of the molecular regulation networks in physiological conditions such as tooth eruption and movement and also for periodontal diseases.

[Clinical characteristics and next generation sequencing of three cases of Listeria monocytogenes meningitis with complications]

Objective: To summarize the clinical characteristics of Listeria monocytogenes meningitis (LMM) with complications, and analyze the outcomes of next generation sequencing. Methods: Clinical characteristics, laboratory findings, imaging features, antibiotics treatment, and next generation sequencing of cerebrospinal fluid were analyzed in 3 LMM patients who were hospitalized in the Department of Infectious Diseases of Beijing Children's Hospital Affiliated to Capital Medical University from July 2015 to November 2017. Results: The three patients were 1-year-old girl, 2-year-old girl, and 9-year-old boy, with normal immune function. They had eaten refrigerated food, milk or dairy products before onset. Symptoms included fever, headache, abdominal pain, diarrhea, vomiting, and convulsions, etc. The complications of two cases (case 2 and 3) were appendicitis and Meckel's diverticulitis. The other one (case 1) was with sepsis and pneumonia. Leukocyte counts in cerebrospinal fluid were elevated in all the three cases, and cranial magnetic resonance imaging showed meningeal or periventricular involvement. All the children were diagnosed with LMM by positive CSF culture. CSF for next generation sequencing was sent after carbapenem antibiotics using, yet all the results were positive. The positive results were returned 2, 9, and 9 days earlier than culture results, respectively. The gene coverage was 5.00%, 7.00%, 0.04%, and the reads was 2 561, 1 011 and 8, respectively. All the three children had recurrent fever despite using cephalosporin. Levels of leukocytes in the blood and CSF further elevated. After using carbapenem antibiotics, patients improved eventually and were discharged from hospital. Conclusions: LMM can occur in children with normal immune function and is usually associated with digestive system symptoms. Listeria monocytogenes can be detected quickly and accurately by the next generation sequencing technology, without being limited to sampling time and antibiotics application.

Expression of orphan GPR56 correlates with tumor progression in human epithelial ovarian cancer

G protein-coupled receptor 56 (GPR56) has been demonstrated to be a significant prognostic predictor in several types of malignances, including melanoma, glioblastoma, breast cancer, colon cancer, and pancreatic cancer. GPR56 has a putative mucin-like extracellular domain, indicating functions for this receptor in the cell-cell interactions and triggering different downstream signaling pathways responsible for regulating cell survival, proliferation, adhesion, and migration. But the expression and clinical significance of GPR56 has not been elucidated in epithelial ovarian cancer (EOC). We detected GPR56 expression by immunohistochemistry in 110 samples of ovarian serous carcinoma to explore the correlation between its expression and clinicopathologic characteristics and overall survival. As the result, we found that GPR56 expression is significantly associated with advanced FIGO stage (P = 0.01) and positive lymph node invasion (P = 0.016), and it serves as an independent unfavorable prognostic factor through univariate and multivariate analysis. GPR56 knockdown could dramatically decrease the proliferation and invasion of epithelial ovarian cancer cells through down-regulating the RhoA-GTP level and up-regulating the E-cadherin level, which indicates GPR56 could promote the progression and invasion of EOC. In conclusion, GPR56 expression was demonstrated as an independent prognostic factor in EOC, suggesting that GPR56 may play an oncogenic role through the Rho and E-cadherin pathway and GPR56 could be a novel potential drug target in EOC.

[Haploidentical hematopoietic stem cell transplantation in the treatment of acquired aplastic anemia in children: a single center retrospective analysis]

Objective: To investigate the safety and efficacy of haploidentical hematopoietic stem cell transplantation with different intensity conditioning regimen in the treatment of childhood aplastic anemia (AA) . Methods: Thirty-seven AA patients who underwent haploidentical transplantation in BaYi Children's Hospital Affiliated to PLA Army General Hospital from January 2013 to January 2017 were enrolled. According to the dosage of conditioning regimen, 34 patients excluding 3 other conditioning regimens were divided into high-dosage group (regimen 2, 22 cases) and low-dosage group (regimen 3, 12 cases). The data of Engraftment, graft-vs-host disease (GVHD), hematopoietic reconstitution, relapse, infection, overall survival (OS) were analyzed. The comparison between the two groups was tested by χ(2) test. Results: A total of 35 of 37 patients achieved primary engraftment; 2 cases died of regimen-related toxicity and severe infection before the infusing of the grafts. The activation rate of CMV and EBV was 60% (21/35) . Post-transplant lymphocyte disease (PTLD) of lung occurred in one case. The cumulative incidences of acute GVHD grade Ⅰ-Ⅳ and chronic GVHD were 29% (10/35) and 34% (12/35) respectively and the incidence of extensive chronic GVHD was 6% (2/35) . The median follow-up time was 18.8 (2.9-44.1) months, the OS was 92% (34/37) .All survived patients were no longer dependent on blood transfusion and none of them had recurrence. Comparing the rates of overall survival(86%(19/22) vs.100%(12/12)) and rates of chronic GVHD(40%(8/20) vs. 17%(2/12)) in regimen 2 and regimen 3 group, there were no significant difference (χ(2)=1.742, 1.841, all P>0.05) . Significant difference was found at the incidence of Ⅰ-Ⅳ acute GVHD (10% (2/20) vs. 50% (6/12) ,χ(2)=6.200, P=0.013). Conclusions: Haploidentical hematopoietic stem cell transplantation is effective and safe. It is suitable for patients who are not eligible for matched donor transplantation. Application of reduced dose preconditioning in haploid transplantation is worth exploring.

[Characteristics and drug resistance of non-O157 Shiga toxin-producing E. coli in animal feces, from Shandong Province]

Objective: To understand the infection status, characteristics and drug resistance of non-O157 Shiga toxin-producing E. coli (STEC) in animal feces in Shandong Province. Methods: From 2015 to 2016, convient sampling method was used to collect 1 022 fresh feces of animals in Weishan county and Laizhou city, and 24 non-O157 STEC were isolated. The serotypes of non-O157 STEC strains were confirmed through serum agglutination test. The susceptibility was explored through the antimicrobial sensitivity experiments. ESBLs activity was confirmed by double-disc diffusion. PCR method was used to detect the resistance genes. PFGE typing was operated to assess the relatedness and variability of the strains. The multi-locus sequence typing (MLST) was adopted to get the allelic profile and ST sequence of strains. Analysis was made on the evolutionary relationship between different ST groups was made through CLC Sequence Viewer and Counting Express. Results: A total of 24 non-O157 STEC were isolated from animal feces. 23 strains were from pig feces, and 1 strain was from cow feces, and the serotypes were more dispersed. All of the 24 strains carried stx2 genes. The highest resistance rate was sulfamethoxazole(22 strains), the mount of cotrimoxazole and nalidixic acid was 18 strains, chloramphenicol was 13 strains, tetracycline was 19, and there was a phenomenon of multiple drug resistance. The drug resistance spectrum was sulfamethoxazole tetracycline-compound novammin-naphthidine-chloramphenicol. All strains were sensitive to cefepime and imipenem. The ESBLs confirmatory test showed that 4 strains of non O157 STEC produced beta lactamase. PCR detected 7 resistance genes, and 4 tetracycline resistance genes (Tet A, Tet B, tetC and tetD) were detected. The beta lactamase resistance genes (blaSHV-1, bla CTX-M, bla TEM) were all negative. 24 strains were divided into 15 PFGE types, and their clustering results were more dispersed and no dominant PFGE type. There were 11 kinds of MLST types, most of them are ST540 and ST5133 types, each of which was 4 strains, and clustered into 1 MLST genomes. Conclusion: The serotypes of non-O157 STEC in animal feces O157 STEC were dispersed, and the resistant rate to common antibiotic was high. MLST typing results presents obvious polymorphism. Surveillance and manage ment of these strains should be strengthened.

[Survey of current status of prevention of venous thromboembolism after thoracic surgery in China]

Objective: To investigate the current status of prevention and treatment of venous thromboembolism (VTE) after thoracic surgery in China. Method: Chinese thoracic surgeons were investigated by the online questionnaire which was based on the Chinese version of International VTE questionnaire added with 6 extra questions with Chinese characteristics. Results: A total of 1 150 valid questionnaires were retrieved, accounting for about 20% of all the Chinese thoracic surgeons. The surgeons participating in this survey came from all over the country, most of whom were experienced professionals with high academic titles.For lung cancer patients, 66.96% (770/1 150) of the surgeons suggested that VTE prophylaxis should start 1 day after lung cancer resection, and 64.61% (743/1 150) of the surgeons suggested extending after discharge. For esophagestomy patients, and 48.35% (514/1 063) of the surgeons suggested that there was no need for patients to extend VTE prophylaxis after discharge. More than half of the surgeons participating in this survey made decision of the method and duration of VTE prophylaxis after lung cancer resection (53.91% (620/1 150)) or esophagectomy (52.49% (558/1 063)) depending on the clinical experience.Low molecular weight heparin was the common choice of most surgeons in VTE prophylaxis. More than half of the surgeons thought that previous history of VTE, advanced age, complicated with thrombophilia, obesity (body mass index>30 kg/m²), duration of surgery longer than 6 hours and family history of VTE were key risk factors of the occurrence of postoperative VTE. Conclusions: The results of this survey are highly credible and are a good reflection of the current status of VTE prevention and treatment after thoracic surgery in China. This survey will play an important role in promoting VTE prevention and treatment in Chinese thoracic surgery department, it will also provide data support for government setting new policies, hospital construction of VTE prevention and control as well as raising physicians' awareness.

THE VALIDITY OF THE STUDY OF OSTEOPOROTIC FRACTURES (SOF) INDEX FOR ASSESSING COMMUNITY-BASED OLDER ADULTS IN TAIWAN

Taiwan’s Ten-Year Long-Term Care Project (TLTCP) version 2.0 has expanded to include frail adults in late 2017; however, tools for measuring frailty remain controversial. On the one hand, it has become common to use Fried’s Frailty Phenotype index to measure older adults’ frailty in Taiwan and advanced countries. On the other hand, the Taiwanese government uses the Study of Osteoporotic Fractures index (SOF index) to assess the degree of frailty and whether to receive publicly-funded exercise programs. This study aimed at assessing properties of tools of the SOF index and Fried’s Frailty Phenotype index among general, community-dwelling older adults in Taiwan. In this cross-sectional survey study, purposive sampling was employed to collect data, with 471 older adults. The participants were older than 65 years and lived in Taipei City. To analyze the data, Spearman’s Rank Correlation Coefficient was employed to understand the association between frailty as measured by the two indexes and area under the curve (AUC) statistics was used to test the respective models by measuring the predictive validity from the two indexes. Study findings showed a moderate association between Fried’s Frailty Phenotype index and the SOF index (p<0.001). However, these two frailty indexes were inconsistent in their ability to predict validity. The result of AUC showed that while the SOF predicted falls better (p <0.001), Fried’s Frailty Phenotype index predicted disability better (p <0.001). Similar to the results from advanced countries, SOF index is a valid tool to evaluate frailty, especially for general, community-dwelling older adults in Taiwan.

[Clinical and pathological features of 13 children with Epstein-Barr virus-positive lymphoproliferative disease]

Objective: To summarize the clinical characteristics, virological and histopathological features, clinical outcome of Epstein-Barr virus-positive lymphoproliferative disease (EBV(+)LPD) in children. Methods: The clinical and follow-up data of 13 children histopathologically diagnosed as EBV(+)LPD in the Department of Infectious Disease of Beijing Children's Hospital between January 2011 and December 2016 were summarized. Results: Of the 13 patients, 5 were males and 8 females. The median age of disease onset was 6.0 years (range 1.3 to 15.0 years). The median duration between disease onset and diagnosis was 3 months (range 1 to 24 months). All the 13 patients had fever, 9 cases had hepatosplenomegaly and lymphoadenopathy, 4 cases had only lymphoadenopathy, 7 cases had reduced peripheral blood cells, 7 cases had lung involvement, 3 cases had central nervous system involvement, 3 cases had cardiac involvement, 3 cases had intestinal involvement, 2 cases had skin involvement and 1 case had abdominal mass. All the 13 patients underwent whole blood EBV-DNA PCR examination and the copies ranged from 1×10(8)/L to 1×10(11)/L. Pathology of lymph node confirmed 6 cases, skin pathology confirmed 2 cases, lung pathology, ileum mucosa pathology, liver pathology, abdominal mass pathology and bone marrow pathology confirmed 1 case each. Among 13 patients, 9 cases presented with EBV-positive T cell lymphoproliferative disease(EBV(+) T-LPD), 2 cases with hydroa vacciniforme (HV) and 2 cases with EBV-positive diffuse large B-cell lymphoma (EBV(+) DLBCL) . All the patients were followed up for 2 days to 65 months after discharge. Among 9 cases of EBV(+)T-LPD, 1 case died in a short time, 1 case died after evolved to T-cell lymphoma, 2 cases recovered after hematopoietic stem cell transplantation, 1 case recovered after the chemotherapy of hemophagocytic lymphohistiocytosis(HLH) 2004 protocol and 4 cases were stable now. Of 2 cases of HV patients, 1 case died after evolved to HV like lymphoma and the other still have symptoms. Among 2 cases of EBV(+) DLBCL, 1 case died shortly after discharge and the other was still stable after chemotherapy. Conclusions: Chronic recurrent fever, lymphadenopathy and hepatosplenomegaly are the most common clinical manifestations in children with EBV(+)LPD. Involvement of lung, central nervous system, intestinal tract, skin and other organs are also involved frequently. For children with chronic fever of unknown cause and accompanied by lymphadenopathy and (or) hepatosplenomegaly, EBV (+) LPD should be considered highly when the whole blood EBV-DNA load continues to increase significantly, early biopsy of the proliferative lesion should be performed to make a definite diagnosis. The prognosis of EBV (+) LPD is poor, and some evolve to lymphoma, hematopoietic stem cell transplantation is an effective way to treat this disease.

Molecular characterization, expression pattern and metabolic activity of flavin-dependent monooxygenases in Spodoptera exigua

Enhanced detoxification is one of the important mechanisms for insecticide resistance. Most research in this field to date has focused on the role of cytochrome P450s. Our previous work revealed that flavin-dependent monooxygenases (FMOs) were involved in metabolic resistance of Spodoptera exigua. In the present study we investigated the molecular characteristics, expression patterns and oxidative activities of SeFMO on insecticides. Three FMO genes, which encode proteins with the typical FMO motifs, were cloned from S. exigua. The oxidative activities of eukaryotically expressed SeFMO enzymes were verified with the model substrate of FMO. Importantly, the SeFMOs had significantly higher oxidative activities on metaflumizone and lambda-cyhalothrin than on model substrates and other insecticides tested. The three SeFMOs were mainly expressed in the midgut, fat body and Malpighian tubules. The tissues responsible for xenobiotic metabolism and their expression characteristics were similar to those of P450s acting as detoxification genes. The study also revealed that the expression of SeFMOs could be induced by insecticide exposure, and that SeFMOs were over-expressed in a metaflumizone-resistant strain of S. exigua. These results suggest that SeFMOs are important insecticide detoxifying enzymes, and that over-expression of FMO genes may be one of the mechanisms for metabolic resistance in S. exigua.

Identification and expression of cathepsin B from the freshwater mussel Cristaria plicata

Cathepsin B plays crucial roles in host immune defense against pathogen infection. In present study, a cathepsin B gene from the freshwater mussel, Cristaria plicata (CpCathB) was cloned and characterized. The full-length cDNA of CpCathB was 1825 bp, and contained a 5' untranslated region (UTR) of 36 nucleotides, an open reading frame (ORF) of 1044 bp and a 3' UTR of 745 bp with a poly (A) tail. The deduced CpCathB protein was encoded as a preproenzyme with 347 amino acid residues and predicted molecular weight of 38.55 kDa. Sequence alignment revealed that CpCathB protein shared 56% - 60.7% identity comparison with other species. The predicted tertiary structure of CpCathB protein was highly similar to that of human. The CpCathB mRNA was expressed in hemocytes, hepatopancreas, adductor muscle, gills and mantle tissues of healthy mussels, and the highest expression level was in hepatopancreas. The transcripts of CpCathB were increased in hemocytes and hepatopancreas from mussels after Aeromonas hydrophila challenge. Moreover, the recombinant CpCathB was expressed in the Escherichia coli Rosetta-gami (DE3) strain. The maximum titer of the anti-CpCathB polyclonal antibodies was 1:640,000.The CpCathB protein had a higher expression in hepatopancreas and mantle and a lower level in hemocytes.