A non-carboxylating pentose bisphosphate pathway in halophilic archaea.

Bacteria and Eucarya utilize the non-oxidative pentose phosphate pathway to direct the ribose moieties of nucleosides to central carbon metabolism. Many archaea do not possess this pathway, and instead, Thermococcales utilize a pentose bisphosphate pathway involving ribose-1,5-bisphosphate (R15P) isomerase and ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco). Intriguingly, multiple genomes from halophilic archaea seem only to harbor R15P isomerase, and do not harbor Rubisco. In this study, we identify a previously unrecognized nucleoside degradation pathway in halophilic archaea, composed of guanosine phosphorylase, ATP-dependent ribose-1-phosphate kinase, R15P isomerase, RuBP phosphatase, ribulose-1-phosphate aldolase, and glycolaldehyde reductase. The pathway converts the ribose moiety of guanosine to dihydroxyacetone phosphate and ethylene glycol. Although the metabolic route from guanosine to RuBP via R15P is similar to that of the pentose bisphosphate pathway in Thermococcales, the downstream route does not utilize Rubisco and is unique to halophilic archaea.

A Novel Defined RAS-Related Gene Signature for Predicting the Prognosis and Characterization of Biological Function in Osteosarcoma.

Background: Osteosarcoma (OS) is the most common primary bone malignancy in children and adolescents with a high incidence and poor prognosis. Activation of the RAS pathway promotes progression and metastasis of osteosarcoma. RAS has been studied in many different tumors; however, the prognostic value of RAS-associated genes in OS remains unclear. On this basis, we investigated the RAS-related gene signature and explored the intrinsic biological features of OS. Methods: We obtained RNA transcriptome sequencing data and clinical information of osteosarcoma patients from the TARGET database. RAS pathway-related genes were obtained from the KEGG pathway database. Molecular subgroups and risk models were developed using consensus clustering and least absolute shrinkage and selection operator (LASSO) regression, respectively. ESTIMATE algorithm and ssGSEA analysis were used to assess the tumor microenvironment and immune penetrance between the two groups. A comprehensive review of gene ontology (GO) and KEGG analyses revealed inherent biological functional differences between the two groups. Results: The consistent clustering showed stratification of osteosarcoma patients into two subtypes based on RAS-associated genes and provided a robust prediction of prognosis. A risk model further confirmed that RAS-related genes are the best prognostic indicators for OS patients. GO analysis showed that GDP/GTP binding, focal adhesion, cytoskeletal motor activity, and cell-matrix junctions were associated with the RAS-related model group. Furthermore, RAS signaling in osteosarcoma based on KEGG analysis was significantly associated with cancer progression, with immune function and tumor microenvironment particularly affected. Conclusion: We constructed a prognostic model founded on RAS-related gene and demonstrated its predictive ability. Then, furtherly exploration of the molecular mechanisms and immune characteristics proved the role of RAS-related gene in the dysregulation in OS.

A Lipoate-Protein Ligase Is Required for De Novo Lipoyl-Protein Biosynthesis in the Hyperthermophilic Archaeon Thermococcus kodakarensis.

Lipoic acid is an organosulfur cofactor essential for several key enzyme complexes in oxidative and one-carbon metabolism. It is covalently bound to the lipoyl domain of the E2 subunit in some 2-oxoacid dehydrogenase complexes and the H-protein in the glycine cleavage system. Lipoate-protein ligase (Lpl) is involved in the salvage of exogenous lipoate and attaches free lipoate to the E2 subunit or the H-protein in an ATP-dependent manner. In the hyperthermophilic archaeon Thermococcus kodakarensis, TK1234 and TK1908 are predicted to encode the N- and C-terminal regions of Lpl, respectively. TK1908 and TK1234 recombinant proteins form a heterodimer and together displayed significant ligase activity toward octanoate in addition to lipoate when a chemically synthesized octapeptide was used as the acceptor. The proteins also displayed activity toward other fatty acids, indicating broad fatty acid specificity. On the other hand, lipoyl synthase from T. kodakarensis only recognized octanoyl-peptide as a substrate. Examination of individual proteins indicated that the TK1908 protein alone was able to catalyze the ligase reaction although with a much lower activity. Gene disruption of TK1908 led to lipoate/serine auxotrophy, whereas TK1234 gene deletion did not. Acyl carrier protein homologs are not found on the archaeal genomes, and the TK1908/TK1234 protein complex did not utilize octanoyl-CoA, raising the possibility that the substrate of the ligase reaction is octanoic acid itself. Although Lpl has been considered as an enzyme involved in lipoate salvage, the results imply that in T. kodakarensis, the TK1908 and TK1234 proteins function in de novo lipoyl-protein biosynthesis. IMPORTANCE Based on previous studies in bacteria and eukaryotes, lipoate-protein ligases (Lpls) have been considered to be involved exclusively in lipoate salvage. The genetic analyses in this study on the lipoate-protein ligase in T. kodakarensis, however, suggest otherwise and that the enzyme is additionally involved in de novo protein lipoylation. We also provide biochemical evidence that the lipoate-protein ligase displays broad substrate specificity and is capable of ligating acyl groups of various chain-lengths to the peptide substrate. We show that this apparent ambiguity in Lpl is resolved by the strict substrate specificity of the lipoyl synthase LipS in this organism, which only recognizes octanoyl-peptide. The results provide relevant physiological insight into archaeal protein lipoylation.

A Structurally Novel Lipoyl Synthase in the Hyperthermophilic Archaeon Thermococcus kodakarensis.

Lipoic acid is a sulfur-containing cofactor and a component of the glycine cleavage system (GCS) involved in C1 compound metabolism and the 2-oxoacid dehydrogenases that catalyze the oxidative decarboxylation of 2-oxoacids. Lipoic acid is found in all domains of life and is generally synthesized as a lipoyl group on the H-protein of the GCS or the E2 subunit of 2-oxoacid dehydrogenases. Lipoyl synthase catalyzes the insertion of two sulfur atoms to the C-6 and C-8 carbon atoms of the octanoyl moiety on the octanoyl-H-protein or octanoyl-E2 subunit. Although the hyperthermophilic archaeon Thermococcus kodakarensis seemed able to synthesize lipoic acid, a classical lipoyl synthase (LipA) gene homolog cannot be found on the genome. In this study, we aimed to identify the lipoyl synthase in this organism. Genome information analysis suggested that the TK2109 and TK2248 genes, which had been annotated as biotin synthase (BioB), are both involved in lipoic acid metabolism. Based on the chemical reaction catalyzed by BioB, we predicted that the genes encode proteins that catalyze the lipoyl synthase reaction. Genetic analysis of TK2109 and TK2248 provided evidence that these genes are involved in lipoic acid biosynthesis. The purified TK2109 and TK2248 recombinant proteins exhibited lipoyl synthase activity toward a chemically synthesized octanoyl-octapeptide. These in vivo and in vitro analyses indicated that the TK2109 and TK2248 genes encode a structurally novel lipoyl synthase. TK2109 and TK2248 homologs are widely distributed among the archaeal genomes, suggesting that in addition to the LipA homologs, the two proteins represent a new group of lipoyl synthases in archaea.IMPORTANCE Lipoic acid is an essential cofactor for GCS and 2-oxoacid dehydrogenases, and α-lipoic acid has been utilized as a medicine and attracted attention as a supplement due to its antioxidant activity. The biosynthesis pathways of lipoic acid have been established in Bacteria and Eucarya but not in Archaea Although some archaeal species, including Sulfolobus, possess a classical lipoyl synthase (LipA) gene homolog, many archaeal species, including T. kodakarensis, do not. In addition, the biosynthesis mechanism of the octanoyl moiety, a precursor for lipoyl group biosynthesis, is also unknown for many archaea. As the enzyme identified in T. kodakarensis most likely represents a new group of lipoyl synthases in Archaea, the results obtained in this study provide an important step in understanding how lipoic acid is synthesized in this domain and how the two structurally distinct lipoyl synthases evolved in nature.

Overexpression of AMPD2 indicates poor prognosis in colorectal cancer patients via the Notch3 signaling pathway.

BACKGROUND: AMPD2 is a critical enzyme catalyzing smooth muscle energy supply and metabolism; however, its cellular biological function and clinical implication in colorectal cancer (CRC) are largely unknown. AIM: To clarify the role of AMPD2 in CRC and study the pathway and prognostic value of its role. METHODS: AMPD2 expression was analyzed by integrated bioinformatics analysis based on TCGA data sets and immunohistochemistry in tissue microarrays, and the correlation between AMPD2 expression and clinicopathological parameters, Notch3 expression, and prognostic features was assessed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis were then performed to investigate the regulatory pathway involved. The effects of AMPD2 expression on CRC cells and Notch3 protein expression were investigated by downregulation and overexpression of AMPD2. RESULTS: AMPD2 mRNA was significantly overexpressed in tumor tissue when compared with normal tissue in a cohort of the TCGA-COAD data set. Biological function enrichment analysis indicated that the Notch pathway strongly correlated with AMPD2 expression, and that the expression of Notch3 and JAG2 mRNA was positively associated with AMPD2 in CRC tissues. In vitro, AMPD2 overexpression markedly reduced Notch3 protein expression in CRC cells, while knockdown of AMPD2 showed the opposite findings. In addition, protein expression was significantly up-regulated in our CRC cohort as indicated by tissue microarray analysis. High expression of AMPD2 protein correlated with advanced depth of tumor and poor differentiation. Furthermore, high AMPD2 expression in CRC tissues was an indicator of poor outcome for CRC patients. CONCLUSION: AMPD2 is commonly overexpressed in CRC, and acts as a metabolism oncogene to induce CRC progression through the Notch signaling pathway. Thus, AMPD2 may be a novel prognostic biomarker for CRC.

A Low Lean-to-Fat Ratio Reduces the Risk of Acute Exacerbation of Chronic Obstructive Pulmonary Disease in Patients with a Normal or Low Body Mass Index.

BACKGROUND Increased risk of acute exacerbation of chronic obstructive pulmonary disease (COPD) has been reported in patients who are overweight and obese. However, the effects of body fat in patients with normal or low body mass index (BMI) and COPD remain unknown. This study aimed to examine the association between acute exacerbations of COPD and the lean-to-fat (LTF) ratio in patients with a normal or low BMI. MATERIAL AND METHODS Patients with COPD (n=68) underwent assessment of body composition, in whom 43 cases had a normal BMI (18.5 to 25 kg/m²) and 14 cases were underweight (<18.5 kg/m²). Patients with COPD were treated according to current clinical guidelines and underwent regular follow-up for one year. Acute exacerbations of COPD were recorded. RESULTS BMI, the fat-free mass index (FFMI), skeletal muscle mass index (SMMI), and LTF ratio had no significant effect of the risk of acute exacerbations of COPD in the whole study cohort, but a low LTF ratio was significantly associated with reduced risk of acute exacerbations of COPD in the subgroup with a BMI<25 kg/m² (OR=4.528; P<0.05). The Fat Mass Index (FMI) had a protective effect in the whole cohort (OR=0.292; P=0.024) and in the subgroup with BMI <25 kg/m² (OR=0.253, P=0.049). The cumulative incidence of acute exacerbations of COPD was significantly increased in the patients with a high LTF ratio in the whole cohort (P=0.047) and in the subgroup with BMI <25 kg/m² (P=0.014). CONCLUSIONS In patients with BMI <25 kg/m², the LTF ratio was positively correlated with the risk of occurrence of acute exacerbations of COPD.

Efficacy and adverse reactions of combination therapy of bevacizumab and 5-fluorouracil in patients with metastatic colon cancer.

PURPOSE: To observe the efficacy and side effects of combined treatment of bevacizumab and 5-fluorouracil in patients with metastatic colon cancer. METHODS: Sixty patients with histopathologically confirmed metastatic colon cancer were treated with bevacizumab and 5-fluorouracil (the study group) or 5-fluorouracil alone (the control group). 400 mg/m2 5-fluorouracil was given intravenously and maintained by a micropump (2400 mg/m2) for 46 hrs. A treatment cycle consisted of 14 days. All patients received at least 4 cycles of treatment. Serum vascular endothelial growth factor (VEGF) concentrations in colon cancer patients of the two groups were evaluated before and after chemotherapy. The short-term treatment efficacy was assessed and followed every 3 months for survival analysis, while adverse reactions were also observed and recorded. RESULTS: Before the treatment, no differences were observed in VEGF levels between the two groups. However, after 4 cycles of chemotherapy, VEGF level in the study group was markedly lower vs the pretreatment level. No difference was observed in VEGF level in the control group after treatment. The effective rate in the two groups after treatment was response rate (RR)=86.7% and 53.3%, respectively (p<0.05). A 24-month follow-up showed that the median progression-free survival (PFS) of the study group was 9.87 months and the median survival 16.9 months. The median PFS of the control group decreased to 6.75 months with median survival of 12.45 months. Data analysis showed significant differences in PFS and median overall survival (OS) between the two groups (p<0.05). Besides, no difference was observed in the adverse reactions between the two groups during treatment (all p>0.05). CONCLUSIONS: Combined treatment of bevacizumab and 5-fluorouracil can reduce the serum VEGF level of patients with metastatic colon cancer and prolong their PFS and OS.

Structure-Based Engineering of Amidase from Pantoea sp. for Efficient 2-Chloronicotinic Acid Biosynthesis.

2-Chloronicotinic acid is a key intermediate of pharmaceuticals and pesticides. Amidase-catalyzed hydrolysis provides a promising enzymatic method for 2-chloronicotinic acid production from 2-chloronicotinamide. However, biocatalytic hydrolysis of 2-chloronicotinamide is difficult due to the strong steric and electronic effect caused by 2-position chlorine substituent of the pyridine ring. In this study, an amidase from a Pantoea sp. (Pa-Ami) was designed and engineered to have improved catalytic properties. Single mutant G175A and double mutant G175A/A305T strains exhibited 3.2- and 3.7-fold improvements in their specific activity for 2-chloronicotinamide, and the catalytic efficiency was significantly increased, with kcat/Km values 3.1 and 10.0 times higher than that of the wild type, respectively. Structure-function analysis revealed that the distance between Oγ of Ser177 (involved in the catalytic triad) and the carbonyl carbon of 2-chloronicotinamide was shortened in the G175A mutant, making the nucleophilic attack on the Oγ of Ser177 easier by virtue of proper orientation. In addition, the A305T mutation contributed to a suitable tunnel formation to facilitate the substrate entry and product release, resulting in improved catalytic efficiency. With the G175A/A305T double mutant as a biocatalyst, a maximum of 1,220 mM 2-chloronicotinic acid was produced with a 94% conversion, and the space-time yield reached as high as 575 gproduct liter-1 day-1 These results provide not only a novel robust biocatalyst for the production of 2-chloronicotinic acid but also new insights into amidase structure-function relationships.IMPORTANCE In recent years, the demand for 2-chloronicotinic acid has been greatly increased. To date, several chemical methods have been used for the synthesis of 2-chloronicotinic acid, but all include tedious steps and/or drastic reaction conditions, resulting in both economic and environmental issues. It is requisite to develop an efficient and green synthesis route. We recently screened Pa-Ami and demonstrated its potential for synthesis of 2-chloronicotinic acid from 2-chloronicotinamide. However, chlorine substitution on the pyridine ring of nicotinamide significantly affected the activity of Pa-Ami. Especially for 2-chloronicotinamide, the enzyme activity and catalytic efficiency were relatively low. In this study, based on structure-function analysis, we succeeded in engineering the amidase by structure-guided saturation mutagenesis. The engineered Pa-Ami exhibited quite high catalytic activity toward 2-chloronicotinamide and could serve as a promising biocatalyst for the biosynthesis of 2-chloronicotinic acid.

Clinical significance of long non-coding RNA ZEB2-AS1 in locally advanced colorectal cancer.

OBJECTIVE: The aim of this study was to investigate the clinical significance of differential expression of long non-coding RNA (lncRNA) ZEB2-AS1 in patients with colorectal cancer (CRC). METHODS: mRNA expression of lncRNA ZEB2-AS1 was evaluated by real-time quantitative PCR on eighty-seven cancerous tissues and adjacent normal mucosal tissues from patients with CRC tissue. Correlation between the lncRNA ZEB2-AS1 expression and clinicopathological characteristics of the colorectal cancer patients was evaluated, and five-year overall survival (OS) was also analyzed according to the lncRNA ZEB2-AS1 expression of the CRC patients. Moreover, Cox Regression Analysis was performed in screening prognosis factors. RESULTS: A significantly upregulated lncRNA ZEB2-AS1 expression, with a fold change of 18.75, was found in CRC tissue compared to the normal tissue. lncRNA ZEB2-AS1 expression in CRC was correlated with death (P<0.001). The five-year OS was 43.2% and 76.7%, respectively, in patients with higher and lower lncRNA ZEB2-AS1 expression. Cox regression analysis showed that location (P=0.020), N1 staging (P=0.021) and lncRNA ZEB2-AS1 lower expression (P<0.001) were independent prognosis factors associated with a better OS. CONCLUSION: Expression of lncRNA ZEB2-AS1 was significantly upregulated in stage III CRC patients and affects the prognosis.

Biocatalytic hydrolysis of chlorinated nicotinamides by a superior AS family amidase and its application in enzymatic production of 2-chloronicotinic acid.

2-Chloronicotinic acid (2-CA) is an important building block for a series of agrochemicals and pharmaceuticals. Amidase-catalyzed hydrolysis of 2-chloronicotinamide is one of the most attractive approaches for 2-CA production. However, development of the bioprocess was plagued by low activity of amidase for 2-chloronicotinamide. In this work, an amidase signature (AS) family amidase from Pantoea sp. (Pa-Ami), with superior activity for nicotinamide and its chlorinated derivatives, was exploited and characterized. Kinetic analysis and molecular docking clearly indicated that chlorine substitution in the pyridine ring of nicotinamide, especially the substitution at 2-position led to a dramatic decrease of Pa-Ami activity. The productivity of the bioprocess was significantly improved using fed-batch mode at low reaction temperature and 2-CA was produced as high as 370 mM with a substrate conversion of 94.2%. These results imply that Pa-Ami is potentially promising biocatalyst for industrial production of 2-CA.

Clinical implication of Sox9 and activated Akt expression in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most leading causes of cancer-related death. Cancer stem cell is responsible for tumor initiation, metastasis and relapse. Sox9 is a pancreatic stem cell marker. PI3K/PTEN/Akt/mTORC is an important signal for maintaining stem cells. The purpose of this study is to determine the expression pattern of Sox9 and p-Akt in human PDAC and its correlation with prognosis. Immunohistochemical analysis was used to explore the expression of Sox9 and p-Akt in 88 human PDAC patients. The Pearson's test was used to compare the clinicopathological parameters between negative and positive expressors. The Pearson's correlation analysis was used to explore the relationship between Sox9 and p-Akt expression. Kaplan-Meier's method and Cox regression analysis were used to analyze patients' survival. The results showed that Sox9 and p-Akt overactivated in PDAC (p = 0.011, p = 0.008). Sox9-positive expression is significantly associated with distant metastasis (p = 0.046). p-Akt-positive expression is significantly associated with distant metastasis (p = 0.000), TNM stage (0.001) and PCNA expression (p = 0.000). Sox9 expression is positively correlated with p-Akt expression (r = 0.314, p = 0.003). In 54 patients with survival information, both Sox9- and p-Akt-positive expressions are associated with unfavorable prognosis (p = 0.002, p = 0.000). Sox9 and p-Akt double-positive expressor showed much poorer prognosis (p = 0.000). Cox regression analysis showed that Sox9- or p-Akt-positive expression and LN metastasis were independent prognostic factors. This study provides the first evidence that Sox9 and p-Akt are both relevant to distant metastasis and proliferation. Our data suggest the potential of Sox9 and p-Akt as prognostic biomarkers for PDAC.

Association of xeroderma pigmentosum complementation group G Asp1104His polymorphism with breast cancer risk: A cumulative meta-analysis.

The xeroderma pigmentosum complementation group G (XPG) gene plays an important role in the DNA nucleotide excision repair (NER) pathway. Several studies have investigated the association between the XPG Asp1104His polymorphism and breast cancer; however, the results have been inconsistent. Therefore, we conducted a meta-analysis of 8 published articles (10 case-control studies) including a total of 5,235 patients with breast cancer and 5,685 healthy controls. The results demonstrated that the XPG Asp1104His polymorphism was not associated with breast cancer in the overall population [His vs. Asp, odds ratio (OR)=1.00, 95% confidence interval (CI): 0.91-1.08; His/His vs. Asp/Asp, OR=0.96, 95% CI: 0.83-1.11; Asp/His vs. Asp/Asp, OR=1.02, 95% CI: 0.94-1.11; His/His+Asp/His vs. Asp/Asp, OR=1.03, 95% CI: 0.92-1.15; and His/His vs. Asp/Asp+Asp/His, OR=0.93, 95% CI: 0.81-1.06]. In the subgroup analysis by ethnicity, no significant association was observed in European subjects. In conclusion, this meta-analysis suggested that the XPG Asp1104His polymorphism is not associated with breast cancer risk.

LSF expression and its prognostic implication in colorectal cancer.

Colorectal cancer (CRC) is the third most common cancer worldwide and the fourth most common cause of cancer death. Therapy failure was the first cause of death. LSF is a transcription factor regulating gene expression of angiogenesis, tumor invasion and proliferation, and is identified as a chemoresistant gene. Real-time PCR and Western blot to analyze mRNA and protein expression of LSF in 23 paired CRC samples. Immunohistochemistry was used to detect protein expression of LSF in 166 paired CRC samples. Both LSF mRNA and protein were upregulated in CRC. High LSF expression in CRC correlated with large tumor size, advanced pN stage, advanced AJCC stage and high Ki-67 index (P < 0.001). High expression of LSF favored worse prognosis. 5-year survival rates of LSF high and low expression were 39.6% and 78.6%, respectively. The 5-year median OS were 34 months and 57 months, respectively. LSF is an important mediator in CRC tumorigenesis and progression, and LSF expression is an important index for and prognostic prediction.

Service functions of private community health stations in China: A comparison analysis with government-sponsored community health stations.

In China, with the restructuring of health care system moving forward, private community health facilities have been playing a complementary but increasingly important role in providing public health and basic medical care services in urban areas. However, only limited evidence is available concerning the service functions of private community health facilities in China. The aim of this study was to explore the functions of private community health stations (PCHSs) to provide evidence-based recommendations for policy-making and practice in the development of urban community health services systems. A total of 818 PCHSs and 4320 government-sponsored community health stations (GCHSs) located in 28 cities of China were investigated in 2008. The percentages of stations that provided health services and the annual workload per community health worker (CHW) were compared between the two types of institutions. The results showed that the percentages of PCHSs providing public health services were significantly higher than those of GCHSs (P<0.05); but no significant differences were found in the percentages of basic medical services providing between PCHSs and GCHSs (P>0.05). The annual workloads of all the public health services and basic medical services per CHW in PCHSs were lighter than those in GCHSs (P<0.05), except for resident health records establishment and health education materials distribution (P>0.05). At present, the GCHSs are still the mainstream in urban China, which will last for a long period in future. However, our findings showed that the annual workloads of CHWs in PCHSs were no heavier than those in GCHSs, and the PCHSs were willing to provide public health services. In view of current inadequacy of health resources in China, it is feasible to further develop PCHSs under the guidance of the government, given that PCHSs can perform the basic functions of community health services, which is useful for the formation of public-private partnerships (PPP) and the improvement of community health services.

Service Functions of Private Community Health Stations in China: A Comparison Analysis with Government-sponsored Community Health Stations / 华中科技大学学报（医学）（英德文版）

In China,with the restructuring of health care system moving forward,private community health facilities have been playing a complementary but increasingly important role in providing public health and basic medical care services in urban areas.However,only limited evidence is available concerning the service functions of private community health facilities in China.The aim of this study was to explore the functions of private community health stations (PCHSs) to provide evidence-based recommendations for policy-making and practice in the development of urban community health services systems.A total of 818 PCHSs and 4320 government-sponsored community health stations (GCHSs)located in 28 cities of China were investigated in 2008.The percentages of stations that provided health services and the annual workload per community health worker (CHW) were compared between the two types of institutions.The results showed that the percentages of PCHSs providing public health services were significantly higher than those of GCHSs (P＜0.05); but no significant differences were found in the percentages of basic medical services providing between PCHSs and GCHSs (P＞0.05).The annual workloads of all the public health services and basic medical services per CHW in PCHSs were lighter than those in GCHSs (P＜0.05),except for resident health records establishment and health education materials distribution (P＞0.05).At present,the GCHSs are still the mainstream in urban China,which will last for a long period in future.However,our findings showed that the annual workloads of CHWs in PCHSs were no heavier than those in GCHSs,and the PCHSs were willing to provide public health services.In view of current inadequacy of health resources in China,it is feasible to further develop PCHSs under the guidance of the government,given that PCHSs can perform the basic functions of community health services,which is useful for the formation of public-private partnerships (PPP) and the improvement of community health services.

CYP1A1 Ile462Val polymorphism contributes to colorectal cancer risk: a meta-analysis.

AIM: To study the relation between CYP1A1 Ile462Val polymorphism and colorectal cancer risk by meta-analysis. METHODS: A meta-analysis was performed to investigate the relation between CYP1A1 Ile462Val polymorphism and colorectal cancer risk by reviewing the related studies until September 2010. Data were extracted and analyzed. Crude odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of relation between CYP1A1 Ile462Val polymorphism and colorectal cancer risk. RESULTS: Thirteen published case-control studies including 5336 cases and 6226 controls were acquired. The pooled OR with 95% CI indicated that CYP1A1 Ile462Val polymorphism was significantly related with colorectal cancer risk (Val/Val vs Ile/Ile: OR = 1.47, 95% CI: 1.16-1.86, P = 0.002; dominant model: OR = 1.33, 95% CI: 1.01-1.75, P = 0.04; recessive model: OR = 1.49, 95% CI: 1.18-1.88, P = 0.0009). Subgroup ethnicity analysis showed that CYP1A1 Ile462Val polymorphism was also significantly related with colorectal cancer risk in Europeans (Ile/Val vs Ile/Ile: OR = 1.22, 95% CI: 1.05-1.42, P = 0.008; dominant model: OR = 1.24, 95% CI: 1.07-1.43, P = 0.004) and Asians (Val/Val vs Ile/Ile: OR = 1.40, 95% CI: 1.07-1.82, P = 0.01; recessive model: OR = 1.46, 95% CI: 1.12-1.89, P = 0.005). CONCLUSION: CYP1A1 Ile462Val may be an increased risk factor for colorectal cancer.

Differentiation of neural precursor cell-derived oligodendrocyte progenitor cells following transplantation into normal and injured spinal cords.

Demyelination contributes to the functional deficits after spinal cord injury (SCI). Therefore, remyelination may be an important strategy to facilitate repair after SCI. Oligodendrocyte precursor cells (OPCs) are immature oligodendrocytes and can differentiate into myelin-forming cells of central nervous system under certain conditions. OPC transplantation is an attractive approach for the treatment of demyelinating diseases. In this study, we transplanted OPCs expressing green fluorescent protein (GFP-OPCs) into normal and injured rat spinal cords to evaluate the differentiation of transplanted OPCs in vivo. Unfortunately, the grafted GFP-OPCs, in spinal cord whether normal or injured, were all differentiated into astrocytes, but not oligodendrocytes. Our further study indicated that inflammatory environment might not be the key factor influencing the differentiation of OPCs. Some spinal cord components, such as bone morphogenetic proteins (BMPs), were the major factors that induced OPCs to differentiate into astrocytes. The three types of BMP receptor (BMPRIA, IB and II) could all be detected in OPCs, and the astroglial differentiation of OPCs induced by spinal cord homogenate extract (SCHE) in vitro could be blocked partly by noggin, an antagonist of BMP. These results suggested that the BMPR signal transduction pathway might be one of the key factors which determine the differentiation direction of engrafted OPCs in spinal cord.

Expression and regulation of major histocompatibility complex on neural stem cells and their lineages.

The expression of major histocompatibility complex (MHC) antigens on neural stem cells (NSCs) and their lineages is tightly related to the fate of these cells as grafts in allogenic transplantation. In this study, we observed that NSCs derived from embryonic rat forebrain expressed MHC class I and class II molecules at a low level, whereas the cells differentiated from NSCs, including neurons, astrocytes, and oligodendrocytes, lost their MHC expression. However, a proinflammatory factor, interferon-gamma (IFN-gamma), could induce and up-regulate the expression of MHC in both NSCs and their differentiated lineages in vitro. These results suggest that predifferentiating NSCs into lineage-limited cells prior to transplantation combined with controlling the local production of proinflammatory cytokines moderately may potentially benefit the survival of transplants.

A simplified method for generating oligodendrocyte progenitor cells from neural precursor cells isolated from the E16 rat spinal cord.

Conditioned medium obtained from B104 neuroblastoma cells (B104CM) has been used widely for inducing oligodendrocyte progenitor cells (OPCs) from neural precursor cells (NPCs). Our previous studies have demonstrated that E16 rat spinal cord-derived NPCs could be induced to differentiate into OPCs using a combination of B104CM and basic fibroblast growth factor (bFGF). Here we report the development of a more efficient and reliable approach to generate large quantities of highly purified OPCs from spinal cord-derived NPCs using a combination of platelet derived growth factor (PDGF) and bFGF. We demonstrated that, after the two factors application, over 90% cells displayed typical bipolar or tripolar morphology and expressed markers for OPCs including A2B5 (90.36 +/- 4.59%), NG2 (93.63 +/- 3.37%) and platelet derived growth factor alpha receptor (PDGFR; 90.35 +/- 1.95%). Our results indicated that the PDGF/bFGF combination is more efficient in generating OPCs than the B104CM/bFGF. And it is a more potent combination of factors in promoting proliferation of OPCs.

Induction of rat neural stem cells into oligodendrocyte precursor cells.

We have previously established a culture method to isolate and cultivate neural stem cells (NSCs) derived from the rat embryonic brain and spinal cord. In the present study, we demonstrate that the spinal cord-derived NSCs can be induced to differentiate into oligodendrocyte precursor cells (OPCs) with a combined treatment composed of (1) conditioned medium collected from B104 neuroblastoma cells (B104CM) and (2) basic fibroblast growth factor (bFGF, 10 ng/ml). After induction, over 95% of the cells displayed bipolar or tri-polar morphology and expressed A2B5 and platelet derived growth factor receptor-alpha (PDGFR-alpha), markers that are specific for OPCs. Among PDGFR-alpha positive OPCs, only a few cells expressed glia fibrillary acidic protein (GFAP) and none expressed beta-tubulin III. In the presence of B104CM and bFGF, OPCs proliferated rapidly, formed spheres, expanded for multiple passages, and maintained their phenotypic properties. Upon withdrawal of B104CM and bFGF, these cells differentiated into either O4/GlaC-positive oligodendrocytes (OLs) or GFAP- and A2B5-positive type-2 astrocytes. Our results indicate that NSCs can be induced to differentiate into OPCs that possess properties of self-renewal and differentiation into oligodendrocytes and type-2 astrocytes, a property similar to that of O-2A progenitor cells. The OPCs can be maintained in an undifferentiated state over multiple divisions as long as both B104CM and bFGF are present in the medium. Thus, large quantity of OPCs can be obtained through this method for potential therapeutical interventions for various neurological degenerative diseases.