[Analysis of Heavy Metal Pollution Evaluation and Correlation of Farmland Soil and Vegetables in Zhaotong City]

A farmland area in Zhaotong City was taken as the research object， and the method of point-to-point collaborative sampling was used to collect farmland soil and vegetables in Zhaotong and test the content of six heavy metals， namely As， Pb， Cu， Zn， Cd， and Cr. The geo-accumulation index and potential ecological risk index were used to evaluate the heavy metal pollution of soil. The health risk model was used to evaluate the risk to the human body imposed by vegetables. The results showed that Cu， Zn， Pb， Cd， and Cr pollution existed in the research area. Compared with the risk screening value of farmland， the over-standard rates were 34.35%， 6.87%， 2.29%， 80.15%， and 6.11%， respectively； Pb， Cd， and Cr were found in vegetables. Compared with the pollutant limit in food， the over-standard rates were 6.87%， 15.27%， and 36.64%， respectively. According to the soil pollution evaluation， Cd in the soil showed a strong ecological risk， and other heavy metals in the soil showed a mild ecological risk. The human health risk evaluation model showed that both non-carcinogenic risk and carcinogenic risk were out of the acceptable range and had a greater influence on children. Correlation analysis showed that As in the soil had an antagonistic effect on Cu and Zn absorption by vegetables， whereas Cr in the soil could promote Cu and Zn absorption by vegetables.

[Standardized nomenclature of oral microorganisms in Chinese: the 2023 update]

Oral microbial community, as an important part of human microbial community, is closely related to oral and general health. Oral microbiological research has become the forefront of international microbiological research. Standardized and unified nomenclature for oral microorganisms in Chinese is of great significance to support the development of oral medicine research. Standardized translation of microbial names is the basis for writing canonical and authoritative professional textbooks and reference books, which helps students to accurately acquire the characteristics and classifications of oral microbes. Unified translation of oral microorganisms is also conducive to academic communication and cooperation, and plays an important role in oral health education and science popularization, which enables oral microbiology knowledge to be accurately disseminated to the public. Therefore, in order to standardize the words in scientific research, funding application, publications, academic exchanges and science popularization within the field of oral medicine, we have fully discussed and revised the Chinese names of oral microorganisms in 2017 edition and ones of newly discovered oral microbes, finally reaching a consensus to form the 2023 edition of Chinese names of oral microorganisms.

[Further understanding and paying attention to normoalbuminuric diabetic kidney disease]

Diabetes mellitus (DM) has grown up to be an important issue of global public health because of its high incidence rate. Diabetic kidney disease (DKD) is the main cause of end-stage kidney disease (ESKD). Therefore, early diagnosis and timely prevention and treatment of DKD are essential for the progress of DM. The clinical diagnosis and staging of DKD are mostly based on the urinary albumin excretion rate (UAER) and estimated glomerular filtration rate (eGFR). However, clinically, DKD patients show normoalbuminuric diabetic kidney disease (NADKD) instead of clinical proteinuria. The old NADKD concept is no longer suitable and should be updated accordingly with the redefinition of normal proteinuria by NKF/FDA (National Kidney Foundation/Food and Drug Administration). Based on the relevant guidelines of DM and chronic kidney disease (CKD) and combined with the current situation of clinical research, the review described NADKD from the aspects of epidemiology, pathological mechanism, disease diagnosis, clinical characteristics and biomarkers, to arouse the new understanding of NADKD in the medical profession and pay attention to it.

[Effects and clinical significance of NLRP3 inflammasome activated by IL-17A in CRSwNP]

Objective: To investigate the effects and clinical significance of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activated by interleukin (IL)-17A in chronic rhinosinusitis with nasal polyps (CRSwNP). Methods: Patients underwent nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-sen University from January 2020 to December 2021 were collected, including 28 CRSwNP (including 19 males and 9 females, aged 19 to 67 years), 22 chronic rhinosinusitis without nasal polyps (CRSsNP) and 22 controls. qRT-PCR was used to detect the expressions of IL-17A, NLRP3, IL-1β and IL-18 in the three groups, and their correlations were analyzed. The positions of IL-17A, NLRP3 and IL-18 in nasal polys were analyzed by immunofluorescence. Western Blotting and ELISA were employed to detect the expression of NLRP3, IL-1β and IL-18 in the human nasal epithelial cells after using IL-17A stimulation or IL-17A receptor inhibitor. Immunofluorescence was used to observe the NLRP3, IL-1β, and IL-18 protein expression after IL-17A stimulating human nasal epithelial cells, and after the use of IL-17A receptor inhibitor and NLRP3 inhibitor MCC950. The correlations between NLRP3, IL-1β, IL-18 and CT scores, nasal endoscopic scores, visual analogue scale (VAS) scores, and sino-nasal outcome test (SNOT) 22 scores of CRSwNP patients were analyzed. SPSS 20.0 software was used for statistical analysis. Results: The expressions of IL-17A, NLRP3, IL-1β and IL-18 in the tissues of CRSwNP patients were significantly higher than those in CRSsNP group(P=0.018,P<0.001,P=0.005, P=0.016) and the control group(all P<0.001). IL-17A was positively correlated with the expression of NLRP3, IL-1β, and IL-18(r ralue was 0.643,0.650,0.629,respectively, all P<0.05). IL-17A, NLRP3, and IL-18 were co-localized in the epithelial propria of polyp tissue. IL-17A stimulated the expressions of NLRP3, IL-1β, and IL-18 in human nasal epithelial cells. After the use of IL-17A receptor inhibitor, the expressions of NLRP3, IL-1β, and IL-18 were significantly down-regulated. After the use of NLRP3 inhibitor MCC950, IL-17A was significantly down-regulated to promote the expression of NLRP3, IL-1β, and IL-18. The expressions of NLRP3, IL-1β and IL-18 were positively correlated with CT, nasal endoscopy, VAS, and SNOT22 scores in patients with CRSwNP. Conclusions: IL-17A promotes the release of IL-1β and IL-18 by activating the NLRP3 inflammasome and aggravates the severity of the disease in CRSwNP.

[Progress in signal centers in early tooth development]

At the early stage of tooth development, the tooth embryo underwent three successive stages: bud stage, cap stage and bell stage through the interaction between epithelium and mesenchymal cells. During these stages, especially during the interphase transition, the presence of signal centers was particularly crucial. Signal center was composed of a small group of oral epithelial cell collections which were formed in a specific sequence, playing a decisive role in signal expression, morphogenesis and cell differentiation by secreting growth factors and other signaling molecules to regulate developmental signaling pathways. This paper reviews the evolution of signal centers as well as the important signal molecules and transcription factors in signal centers since the formation of dental placode.

[Frailty trajectories in people aged 50 years and above in China]

Objective: To identify distinct frailty trajectories in a cohort of nationwide community adults aged 50 years and above, and explore the relationship between frailty trajectories and their socioeconomic characteristics and behavioral factors at baseline survey. Methods: Data were from the three waves of "Global Ageing and Adult Health Research" (SAGE) by World Health Organization in China. The frailty index is generated from 32 items. Group-based trajectory modeling using a censored normal model was conducted to identify the patterns in frailty progression over time. Multinomial logistic regression model was used to examine the effect of socioeconomic status and behavioral factors on the frailty trajectories. Results: A total of 4 303 adults aged 50 years and above with complete data from all three rounds of project were included in the final analysis. Three frailty trajectories were identified: low and stable trajectory (LT) (56.8%), moderately increased trajectory (MT) (34.4%) and highly increased trajectory (HT) (8.8%). The results of the multinomial logistic regression analysis showed that the HT group was more likely to be women (OR=1.88, 95%CI:1.22-2.92) and rural residents (OR=1.87, 95%CI:1.29-2.70) compared with the LT group. In terms of household wealth per capita, there was a clear gradient in ORs, the people with lower household wealth were more likely to be classified in the HT group. Conclusion: This study identified three patterns of progression of frailty trajectories in population aged 50 years and above in China and highlighted that interventions should target those vulnerable populations with rapid progression of frailty.

[A prospective cohort study on the association between grip strength and cognitive function in adults aged 50 years and above]

Objective: To evaluate the association between grip strength (GS) and cognitive function in a population-based longitudinal cohort of Chinese adults aged ≥50 years. Methods: The study population of 3 600 adults was from the baseline survey and two rounds of follow up of World Health Organization (WHO) study of global ageing and adult health (SAGE) in five districts of Shanghai (Hongkou, Huangpu, Minhang, Qingpu and Pudong) after excluding individuals with self-report stroke and depression. The effects of baseline GS on cognitive function and its changes were evaluated. Factor analysis was applied to generate an overall cognition score based on verbal recall trials, verbal fluency test, forward digit span test and backward digit span test. Linear mixed effects model was used to examine the predictive capability of baseline GS for changes in cognitive function. Results: A total of 3 600 participants aged (61.2±8.1) years at baseline survey were included in this study, including 1 668 (46.3%) men and 1 932 (53.7%) women. The average of baseline GS and total cognitive function score were (28.19±12.18) kg and (58.93±14.56) respectively. Cognitive function score declined significantly during the follow-up, however, the changes were different among different age groups, education level groups and household income groups. After adjusted for age, education level, marital status, household income, co-morbidity of chronic conditions, drinking status, smoking status, physical activity level, vegetable/fruit intakes and BMI, no relationships between the baseline GS and cognitive score at baseline survey and at 1^st follow-up were observed, however, compared with lower GS quartile group, there was a significant relationship between higher baseline GS level and better cognitive function at 2^nd follow-up. The participants with highest GS quartile had better cognitive performance over time (male: β=1.938,95%CI:0.644-3.231,P=0.003, female: β=2.192,95%CI:0.975-3.409,P<0.001 and those aged 50-64 years: β=1.652,95%CI:0.646-2.659,P=0.001) than those with the lowest quartile. Conclusions: Higher baseline GS was significantly related to better cognitive function with slow decline. Thus, it is an indicator of cognitive function in middle-aged and elderly Chinese.

[The expression profile and potential regulatory mechanism of ACE2 in chronic rhinosinusitis with nasal polyps]

Objective: To preliminarily analyze the expression of angiotensin-converting enzyme 2 (ACE2) and to investigate its potential regulatory mechanism in chronic rhinosinusitis with nasal polyps (CRSwNP). Methods: Patients underwent nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-sen University from February 2020 to May 2021 were selected, including 17 males and 6 females, aging from 23 to 66 years old. Expression of ACE2 was evaluated via immunohistochemical staining in controls with non-chronic rhinosinusitis, non-eosinophilic CRSwNP (non-ECRSwNP), and eosinophilic CRSwNP (ECRSwNP) tissue, respectively. Correlations between ACE2 and the indicated Th1/Th2-related cytokines (IFN-γ, IL-4, IL-5, IL-13, IL-25, IL-33, TSLP and periostin) were analyzed based on GSE72713 dataset. Protein-protein interaction (PPI) network was constructed via string database, immune infiltration of GSE72713 dataset was evaluated using cibersort algorithm. ACE2 was comprehensively analyzed by microRNA regulatory network, gene set enrichment analysis (GSEA) and pharmacological analysis. Statistical analysis was performed using GraphPad 7.0 and SPSS 20.0 software. Results: ACE2 was up-regulated in non-ECRSwNP compared with ECRSwNP. Microarray analysis showed that ACE2 was positively correlated with IFN-γ while inversely correlated with IL-5, IL-13 and periostin significantly. Analysis of immune infiltration suggested that ACE2 expression correlated positively with the number of M1 macrophage while negatively with M2 macrophage. GSEA demonstrated that interferon-related signaling pathways were up-regulated in non-ECRSwNP, and miRNA-200B/miRNA-200C/miRNA-429 pathways targeting ACE2 were enriched in ECRSwNP. Results of pharmacological analysis indicated that ampicillin was able to promote the expression of ACE2 whereas acetaminophen could down regulated the expression of ACE2. Conclusion: Expression pattern of ACE2 is varied in non-ECRSwNP and ECRSwNP, which may be related to the different infiltration of indicated cytokines and different regulatory pathways of miRNA.

[Cross-sectional study of association between dietary pattern and cognitive performance in people aged 50 and above years in Shanghai]

Objective: To investigate the association between dietary pattern and cognitive performance in local residents aged ≥50 years in Shanghai. Methods: Data were obtained from the second round of Study of Global Ageing and Adult Health (SAGE) survey in Shanghai. Dietary patterns were surveyed by factor analysis. Cognitive tests were conducted to assess subjects' cognitive performance, including verbal recall, verbal fluency and digit test. Multiple linear regression analysis was used to evaluate the relationship between dietary patterns and cognition performance. Results: A total of 4 132 subjects with complete dietary and cognitive performance test data were included. Factor analysis was used to obtain three dietary patterns: including plant-based pattern, high animal-food pattern, high salt-oil pattern. After controlling for gender, age, education level and other factors, it was found that plant-based pattern (β=0.26,95%CI: 0.17-0.36) and high animal-food pattern (β=0.18, 95%CI:0.06-0.29) were positively associated with total cognitive test score while high salt-oil pattern (β=-0.28, 95%CI:-0.85--0.07) was negatively associated with verbal fluency test score. Conclusion: A dietary pattern with high intake of plant food and appropriate intake of animal food might be associated with better cognitive function of residents aged ≥50 years.

[Expression of CD8+Treg cells in chronic rhinosinusitis and its correlation with eosinophilic infiltration]

Objective: To detect the percentages of CD8⁺Treg cells in the nasal mucosa and peripheral blood of chronic rhinosinusitis (CRS) and to explore their correlation with eosinophilic infiltration. Methods: Thirty-three chronic rhinosinusitis with polyp (CRSwNP), 26 chronic rhinosinusitis without polyp (CRSsNP) and 27 control patients who were collected with the nose mucosal tissue and peripheral blood in the Third Affiliated Hospital of Sun Yat-sen University from March 2017 to October 2018 were selected, including 59 males and 27 females, aging from 18 to 72 years. Hematoxylin and eosin (HE) staining was used to observe the number of eosinophils in the nasal tissues and to classify the CRS into eosinophilic CRS (ECRS) and non-eosinophilic CRS (Non-ECRS). Flow cytometry was used to detect the percentages of CD4⁺ and CD8⁺T cells in lymphocytes of nasal mucosa and peripheral blood. The percentages of CD8⁺Foxp3⁺Treg cells, CD8⁺Foxp3^-IL-10⁺Treg cells, CD8⁺IFN-γ⁺T cells (Tc1), CD8⁺IL-4⁺T cells (Tc2) and CD8⁺IL-17A⁺T cells (Tc17) in lymphocytes of nasal mucosa and peripheral blood were also tested. Besides, the percentages of Foxp3⁺TGF-β⁺Treg cells and Foxp3⁺IL-10⁺Treg cells in CD8⁺T cells were determined. All data were represented by M (IQR). GraphPad 7.0 and SPSS 16.0 were used for illustration and statistical analysis. Results: The percentage of CD8⁺T cells (37.75%(17.35%)) was higher than that of CD4⁺T cells (4.72%(4.29%)) in nasal mucosa (Z=-5.70, P<0.001), while lower (23.60%(9.33%)) than that of CD4⁺T cells (44.05% (10.93%)) in peripheral blood (t=9.72, P<0.001). CRSwNP patients possessed the highest Tc2 (1.82% (1.22%)) and Tc17 (1.93% (2.32%)) percentages than CRSsNP (Tc2: 0.84% (0.79%); Tc17: 0.54% (1.04%)) and control (Tc2: 1.09% (0.92%); Tc17: 0.47% (0.51%), both P<0.05) patients. While, CRSwNP patients possessed the lowest CD8⁺Foxp3⁺Treg cells percentage (0.10% (0.32%)) than CRSsNP (0.43% (1.45%)) and control (0.48% (0.83%), Z value was -2.24, -2.22, respectively, P value was 0.025, 0.027, respectively). The percentages of Foxp3⁺TGF-β⁺Treg cells and Foxp3⁺IL-10⁺Treg cells of CD8⁺T cells in nasal mucosa in CRSwNP were also lower than controls (Z value was 1.46, 0.49, respectively, both P=0.001). Moreover, the percentage of CD8⁺Foxp3^-IL-10⁺Treg cells of CD8⁺T cells was decreased in nasal mucosa of CRSwNP patients (0.14% (0.28%)) when compared with that of CRSsNP (0.89% (0.81%), Z=0.61, P=0.03). ECRS patients had the lower percentages of CD8⁺Foxp3⁺Treg cells (0.07% (0.44%)) and CD8⁺Foxp3^-IL-10⁺Treg cells (0.13% (0.21%)) than Non-ECRS patients (CD8⁺Foxp3⁺Treg cells: 0.53% (0.75%); CD8⁺Foxp3^-IL-10⁺Treg cells: 0.29% (0.76%), t value was 2.14, 2.78, respectively, both P<0.05). The percentage of CD8⁺Foxp3⁺Treg cells and the ratio of CD8⁺Foxp3^-IL-10⁺T per CD8⁺T cells were negatively correlated with the percentage of eosinophils in CRS patients(R² value was 0.56, 0.78, respectively, both P<0.001). There was no significant difference in the distribution of CD8⁺Fxop3⁺Treg cells and CD8⁺Fxop3^-IL-10⁺Treg cells in peripheral blood among different groups. Conclusion: The percentages of CD8⁺Treg cells decrease in CRSwNP patients, especially in ECRS patients, which are opposite to that of Tc2 and Tc17, and negatively correlate with the eosinophils percentage. This indicates that the decrease in the ratio of CD8⁺Treg cell may be associated with the immune-imbalance and eosinophilic infiltration in nasal mucosa of CRS patients.

[miR-18a enhances the radiosensitivity of nasopharyngeal carcinoma cells through inducing autophagy]

Objective: To explore the impacts of miR-18a overexpression or depression on the radiosensitivities of nasopharyngeal carcinoma cell line CNE1 and CNE2 and underlying mechanisms. Methods: CNE1 and CNE2 were transfected with miR-18a mimics, inhibitor and the corresponding control vectors. qRT-PCR and western blot were used to determine the ataxia telangiectasia mutated (ATM) expressions in CNE1 and CNE2. CNE1 and CNE2 with stably expressing miR-18a and miR-18a siRNA were constructed. Methyl thiazolyl tetrazolium (MTT) assay was used to detect the impacts of the miR-18a overexpression or depression combined with irradiation on the cell growth. Flow cytometry was used to detect the cell apoptosis and cell cycle. Colony formation assay was used to evaluate the raodiosensitivities of cells. Acridine orange (AO) staining and western blot were used respectively to test the autophagy and the expressions of related proteins. Independent samples t test was used to compare the mean value between groups by using SPSS 16.0. Results: ATM mRNA was decreased significantly in CNE1 and CNE2 cells transfected with 100 or 200 nmol/L miR-18a mimics for 48 hours (CNE1: RQ=0.174±0.139 and 0.003±0.001, t=9.939 and 19 470.783;CNE2: RQ=0.024±0.008 and 0.019±0.012, t=270.230 and 137.746, respectively, all P<0.001). ATM proteins were also decreased after transfected with 100 or 200 nmol/L miR-18a mimics for 72 hours. While in the cells transfected with 100 and 200 nmol/L miR-18a inhibitor for 48 hours, the expressions of ATM mRNA were upregulated significantly (CNE1: RQ=9.419±2.495 and 2.500±1.063, t=-4.427 and -41.241; CNE2: RQ=7.210±0.171 and 115.875±15.805, t=-62.789 and -12.589, all P<0.05), and the expressions of ATM proteins increased after transfected for 72 hours. The growth of cells with miR-18a overexpression plus 4 Gy irradiation were obviously inhibited compared to that of cells with the 4Gy irradiation alone; while the growth of miR-18a-inhibited cells increased compared to that of cells with 4 Gy irradiation alone (all P<0.05). CNE1 transfected with 100 nmol/L miR-18a mimics plus 4 Gy irradiation showed the higher apoptosis rate than the cells with 4 Gy irradiation alone ((22.9±2.1)% vs. (16.3±1.0)%, t=-4.870, P<0.01). Compared to the cells with 4 Gy irradiation alone, miR-18a-overexpressed cells plus 4 Gy irradiation decreased their percentages in G1 phases ((20.2±3.0)% vs. (29.8±4.4)%, t=3.119) and G2/M phases ((21.5±0.9)% vs. (33.4±3.1)%, t=6.410, P<0.05 for both), and increased their percentages in S phases ((56.7±4.9)% vs. (36.8±6.4)%, t=-4.246, P<0.05), and these cells possessed less colony number after exposure to different doses of irradiation, more autophagy-lysosome number, and more expressions of LC3 proteins (all P<0.05). There were no significant differences in the expressions of p62 expressions between different groups of cells. Conclusion: Overexpression of miR-18a can enhance the radiosensitivities of NPC cells by targeting ATM to abrogate G1/S, G2/M arrest and to induce autophagy and apoptosis.

[The expression of Notch pathway in nasal polyps and its correlation with the decreased Treg percentage and eosinophil infiltration]

Objective: To investigate the correlation between Notch pathway expression in nasal polyps and Treg percentage and Eos infiltration. Methods: Patients with chronic sinusitis and simple nasal septum deviation who received nasal endoscopic surgery in the Third Affiliated Hospital of Sun Yat-Sen University between November 2012 and August 2018 were selected and enrolled in CRS group and control group respectively. Nasal mucosa tissues were collected from 30 CRSsNP patients (14 males and 16 females aged from 18 to 63), 58 CRSwNP patients (38 males and 20 females aged from 18 to 65) and 29 patients (19 males and 10 females aged from 20 to 57), who underwent nasal endoscopic surgery for correction of simple nasal septum deviation. Hematoxylin-eosin(HE) staining was used to observe the infiltration of eosinophilic granulocytes in the tissues and to classify chronic sinusitis with polyps (CRSwNP) into eosinophilic chronic rhinosinusitis with nasal polyps (Eos-CRSwNP)and non-eosinophilic chronic rhinosinusitis with nasal polyps (Eos-CRSwNP). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of Notch pathway receptors (Notch-l, 2, 3, 4) and their ligands (Jagded-l, Jagded-2, Delta-l, Delta-3and Delta-4) in the nasal mucosa of each group, as well as the expression of Th2 cytokines (IL-4, IL-5, IL-13), eosinophilic cationic protein (ECP)and the key transcription factor Foxp3 in Treg cells. Finally, flow cytometry was used to detect CD4+CD25+Foxp3+ Treg cells in nasal mucosa of each group. Results: Compared with controls, the expression of Th2 cytokines (IL-4, IL-5, IL-13) in CRSsNP and non-Eos-CRSwNP patients was the highest in Eos-CRSwNP (F=16.930,9.197,9.116, all P<0.05). Foxp3 had the lowest expression in Eos-CRSwNP patients and was lower than non-Eos-CRSwNP patients (F=2.780,P<0.05), and was negatively correlated with ECP (r=-0.326,P<0.05). Compared with controls, Eos-CRSwNP patients in CRSsNP patients and non-Eos-CRSwNP patients exhibited a significantly lower frequency of CD4+CD25+Foxp3+Treg cells (F=13.140, all P<0.01). The expression of Notch-l and Jagged-l in Eos-CRSwNP was significantly higher than that of the controls, CRSsNP patients and non-Eos-CRSwNP patients (F=5.953/F=6.380, P<0.05). In the nasal polyp group, the expression of Notch-l and Jagged-l showed significantly negative correlation with Foxp3 (r=-0.611/-0.346, all P<0.05), and positive correlation with Th2 cytokines (IL-4, IL-5, IL-13) and ECP, respectively (r=0.781/0.459,0.621/0.601,0.605/0.490,0.464/0.668, all P<0.05). There was no significant difference in the expression of receptor and ligand of the other Notch pathway among the groups. Conclusion: Abnormal activation of Notch-l/Jagged-l pathway may be involved in decreasing Treg ratio in Eos-CRSwNP, thereby promoting Th2 inflammatory response and Eosinophil infiltration.

[Association between grip strength, rapid gait speed and cognition in people aged 50 and above in Shanghai during 2009-2010]

Objective: To investigate the association between grip strength, rapid gait speed and cognition in people aged 50 and above in Shanghai. Methods: Cross-sectional data was collected from the World Health Organization (WHO) study on global ageing and adult health (SAGE) wave 1 (2009-2010). A questionnaire survey was conducted among 8 643 participants aged 50 years old and above selected by using multistage random cluster sampling strategies in Shanghai. Factor analysis was applied to evaluate and generate cognitive function overall score.Association between grip strength, rapid gait speed and cognition was examined by a two-level hierarchical linear model. Results: A total of 8 175 participants were included in this study, who were (62.9±9.7) years old, including 3 782 (46.3%) males. The average grip strength and rapid gait speed of participants were (27.46±12.01) kg and (1.44±0.43) m/s respectively. The average scores of verbal recall (VR), verbal fluency (VF), forward digit span (FDS), backward digit span (BDS) and total cognitive scores were (5.72±0.09), (12.67±0.35), (6.84±0.10), (4.32±0.14) and (60.50±0.95) respectively. Grip strength was positively associated with VR, VF, FDS, BDS and overall cognition (standardized β=0.036, 0.079, 0.042, 0.046 and 0.043 respectively, P<0.05), and rapid gait speed was also positively associated with VR, VF and overall cognition (standardized β=0.040, 0.031, 0.039 respectively, P<0.05) after adjusted for age, sex, residence, education level, marital status, household income, co-morbidity of chronic conditions, BMI, drinking, smoking, fruits, vegetables intake and physical activities. Conclusion: Grip strength and rapid gait speed are both positively associated with cognitive function of people aged 50 and above, which would be indicators to evaluate their cognition.

[Expression and cellular provenance of interleukin 17A in non-eosinophilic chronic rhinosinusitis with nasal polyps]

Objective: To investigate the expression and cellular provenance of interleukin 17A (IL-17A) in non-eosinophilic chronic rhinosinusitis with nasal polyps (nECRSwNP), and to analyze the possible reasons for its different expression. Methods: Samples were collected from 14 patients with eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) and 28 patients with nECRSwNP, who underwent functional endoscopic sinus surgery in the Third Affiliated Hospital of Sun Yat-sen University from January 2017 to May 2018, including 33 males and 9 females, with the age ranging from 18 to 65 years old. Enzyme linked immune sorbent assay (ELISA) and flow cytometry were used to investigate the expression and cellular origins of IL-17A in the nasal tissue of ECRSwNP and nECRSwNP groups. Then the difference of quantity and differentiation ability of the major cells producing IL-17A between ECRSwNP and nECRSwNP groups were analyzed by flow cytometry. Finally, the expressions of IL-6, transforming growth factor-β(TGF-β), and IL-23, which were considered as the important factors in promoting Th17/Tc17 differentiation in CRSwNP and their correlation with IL-17A, were analyzed by ELISA. Statistical analysis was performed using IBM SPSS 20. Results: The IL-17A protein levels and IL-17A(+)lymphocyte percentages were higher in nECRSwNP group compared with that of the ECRSwNP group (158.56 (167.76) pg/ml (M(QR)) vs. 9.42 (11.33) pg/ml, 10.21%±1.54% (x±s) vs. 3.93%±0.80%, Z=2.95, t=3.62, all P<0.01). Tc17 cells (CD8(+)T cells producing IL-17A) and Th17 cells (CD4(+)T cells producing IL-17A) were major IL-17A producers in both ECRSwNP and nECRSwNP group. Further analysis revealed that there was no significant difference in quantity of CD8(+)and CD4(+)T cells between ECRSwNP and nECRSwNP group, but the differentiation ability about CD8(+)and CD4(+)T cells differentiating into Tc17 and Th17 in nECRSwNP group was stronger than that in ECRSwNP. The high expressions of IL-6 and TGF-β, which were considered as the important factors in promoting Th17/Tc17 differentiation were also found in nECRSwNP group compared with ECRSwNP (56.07 (234.25) pg/ml vs. 8.27 (12.51) pg/ml, (5.44±0.34) pg/ml vs. (4.17±0.22) pg/ml, Z=2.426, t=2.29, all P<0.05). But the difference in expression of IL-23 was not significant difference between the two groups. Moreover, the expression of IL-17A showed significantly positive correlation with IL-6 (r=0.615, P=0.009). No positive correlation between IL-17A and TGF-β or IL-23 was observed. Conclusions: The expression of IL-17A in nasal mucosa of nECRSwNP patients is significantly higher than that of ECRSwNP, which is due to the increase of expression and differentiation of Tc17/Th17 cells. IL-17A shows positive correlation with IL-6 in CRSwNP, which is the important factor in promoting Th17/Tc17 differentiation.

[Expression, purification and polyclonal antibody preparation of the Schistosoma japonicum SjGrpE protein]

OBJECTIVE

To investigate the biological properties of Schistosoma japonicum SjGrpE protein, and to express and purify the recombinant SjGrpE protein and test its immunogenicity.

METHODS

The amino acid composition, molecular weight, hydrophilicity and hydrophobicity, transmembrane region, signal peptide, localization, phosphorylation site, ubiquitination site, glycosylation site, secondary and tertiary structures and B cell epitopes of the SjGrpE protein were predicted using bioinformatics analyses. The SjGrpE gene was amplified using PCR assay using S. japonicum cDNA as a template, double enzyme-digested and linked to the pET28a vector to yield the recombinant plasmid pET28a-SjGrpE. The recombinant plasmid pET28a-SjGrpE was transformed into Escherichia coli BL21, and then IPTG was employed to induce the expression of the target protein, which was purified by nickel ion affinity chromatography. After mice were immunized with the recombinant SjGrpE protein, mouse sera were collected, and the polyclonal antibody against the SjGrpE protein was characterized.

RESULTS

SjGrpE protein, which was identified as a hydrophilic protein, was predicted to have a molecular weight of approximately 24.3 kDa without transmembrane regions or signal peptides, and locate in the mitochondrion. SjGrpE protein contained 18 phosphorylation sites and 2 ubiquitination sites, but had no glycosylation sites. In addition, SjGrpE protein contained 5 B-cell epitopes. The full length of SjGrpE gene was approximately 660 bp. The recombinant pET28a-SjGrpE plasmid was successfully generated, and the recombinant SjGrpE protein was obtained following the affinity chromatography, which stimulated mice to secrete high-titer antibodies.

CONCLUSIONS

The recombinant SjGrpE protein has been successfully prepared and this recombinant protein has a high immunogenicity, which provides a basis for evaluating its value as a vaccine candidate for S. japonicum infections.

[Influence on physical development of children aged 18 months from HIV-positive mothers for prevention mother to child transmission of HIV]

Objective: To explore influence on physical development of children aged 18 months from HIV-positive mothers for prevention mother to child transmission of HIV (PMTCT) in Guangxi Zhuang autonomous region, and provide evidence for the improvement PMTCT program. Methods: This retrospective case control study was conducted in 554 HIV negative infants aged 18 months whose HIV positive mothers had received PMTCT services reported through PMTCT system database from January 1, 2010 to December 31, 2017 and 1 109 healthy infants born in 2017, whose mothers were healthy, in Lingshan, Luzhai, and Hengxian counties, ranking top three counties with high HIV infection prevalence, in Guangxi. PMTCT data and physical development data such as height, weight and head circumference of children aged 18 months were collected. The physical dysplasia in the infants was defined as at least one of the three main indicators of height, weight and head circumference below the normal range. Results: The number of HIV-positive mother and their infants in the case group were 667 and 554 respectively, and the PMTCT rates were 91.15% (608/667) and 96.57% (535/554) respectively. HIV positive rate, mortality rate and mother to child transmission rate of the infants aged 18 months were 1.44% (8/554), 3.07% (17/554) and 1.91% (8/418) respectively, and the physical examination results of the infants aged 18 months showed that the physical dysplasia rate was 30.51% (169/554). Among the 1 109 infants in the control group, the physical dysplasia rate was 9.83% (109/1 109). The difference between the case group and the control group was significant (P<0.01). Conclusion: The PMTCT rates of HIV positive mother and their children were more than 90.00%, respectively. However, poor physical development rate of infants aged 18 months were more than 30.00%. The possible influence of PMTCT on physical development of the infants aged 18 months of HIV positive mother's needs to be further studied.

[Association between edentulism and cognition among people aged 50 and over]

Objective: To investigate the association between edentulism and cognition in people aged 50 and over in China. Methods: Cross-sectional data was collected from the first wave of World Health Organization Study on global AGEing and adult health in China, among people aged 50 and over in China. A comprehensive cognitive test was used to assess cognitive functions, including verbal recall (VR), verbal fluency (VF), forward digit span (FDS) and backward digit span (BDS) among the subjects. Association between edentulism and cognition was examined by a two-level (individual level and community level) linear model. Results: A total of 12 843 individuals aged 50 years and over were included for analysis, with an average age of (63.0±9.3) years. The overall prevalence of edentulism was 11.0%. The edentulous adults had lower mean scores of VR (4.55), VF (10.88), FDS (6.25), BDS (2.96) and overall cognition (49.15) (P<0.001). Edentulism was negatively associated with VR (β=-0.216, 95%CI: -0.370 - -0.062), FDS (β=-0.186, 95%CI: -0.293 - -0.078) and overall cognition (β=-1.703, 95%CI: -3.025 - -0.381) after adjusted for age, sex, residence, education level, marital status, household income, co-morbidity of chronic conditions, BMI, smoking and drinking alcohol. Conclusion: Edentulism was related with lower cognition level in people aged 50 and over in China.

[Association between daily sedentary time and frailty among people aged 50 years and over]

Objective: To investigate the association between daily sedentary time and frailty among people aged 50 years and over. Methods: Cross-sectional data was collected from the first wave of World Health Organization Study on global AGEing and adult health in China. A two-level (individual level and community level) logistic model was performed to identify the association between daily sedentary time and frailty. The dose-response relationship between them was analyzed by restrictive cubic spline curve. Results: A total of 13 175 individuals aged 50 years and over were included for analysis. A positive association between daily sedentary time and frailty was noticed, both in urban (OR=1.22, 95%CI: 1.17-1.27) or rural areas (OR=1.11, 95%CI: 1.05-1.18) under study. The dose-response curve showed that daily sedentary time and frailty might present an approximate linear relationship. Conclusion: Results from this study showed significant association exsited between daily sedentary time and frailty, approximately with a linear dose-response relationship.

[Association between frailty and sleep duration among people aged 50 years and over]

Objective: To investigate the association between sleep duration and frailty among people aged 50 years and over. Methods: Cross-sectional data was collected from the first wave of World Health Organization Study on global AGEing and adult health in China. Frailty index was constructed on the proportion of deficits, out of the 40 variables. A two-level (individual level and community level) linear model was performed to identify the related factors on frailty. All the models were stratified by age, gender, residence (urban/rural). Restricted cubic spline was performed to graphically evaluate the dose-response association between self-reported sleep duration and frailty. Results: A total of 13 175 individuals aged 50 years and over participated in this study. Without adjusting on any confounding factors, shorter or longer sleep duration significantly increased the risk of weakness compared with normal sleep time (OR=2.05, 95%CI: 1.71-2.44; OR=1.35, 95%CI: 1.12-1.63). After adjusting for confounding factors such as gender, age, residence, education, family assets, vegetable, smoking, drinking and physical activity, a positive association between short sleep duration and frailty was noticed compared with normal sleep time (aOR=1.60, 95%CI: 1.27-2.01). The results of stratified analysis on sex, age and urban and rural areas showed that, after adjusting for gender, age, residence, education level, family assets, intake of vegetables and fruits, smoking, drinking and physical activity, only shorter sleep duration was positively correlated with the risk of weakness. In addition, among people aged 65 years and over, adjusted for confounding factors, the risk of weakness increased by 91%, compared with normal sleep time (aOR=1.91, 95%CI: 1.46-2.49). The dose-response curve also showed that the sleep duration and frailty present an approximate "U" shaped relationship. Conclusion: Short sleep duration might be associated with frailty.

[Association between low handgrip strength and air pollution among people aged 50 years and over]

Objective: To examine the association between long-term exposure to ambient PM(2.5) combined with indoor air pollution and handgrip strength among people aged 50 and over. Methods: Data were from the first wave of World Health Organization Study on global AGEing and adult health in China. Ambient annual concentration of PM(2.5) was estimated by using the satellite data we also investigated the use of fuels and chimneys as indoor air pollution. A two-level (individual level and community level) linear model was applied to examine the association between long-term exposure to ambient PM(2.5) combined with indoor air pollution and the handgrip strength. Results: A total of 13 175 individuals aged 50 years and over were included for analysis. The handgrip strength was (26.67±0.54) kg. Ambient PM(2.5) was found to be significantly associated with the risk of decreased handgrip strength. Outdoor PM(2.5) concentration was negatively correlated with handgrip strength (β=-0.23, 95%CI: -0.31 - -0.14) decrease in handgrip strength after adjusting for gender, age, residence, education, household assets, intake of vegetables and fruits, smoking and drinking, physical activity. In rural area, compared to those who used solid fuel, use of clean fuel increased (β=1.41, 95%CI: 0.36-2.46) handgrip strength. But in urban area, we did not find any statistically significant association between the use of clean fuel and handgrip strength (β=0.19, 95%CI: -0.95-1.32). Conclusion: This study found that long-term exposure to ambient PM(2.5) combined with indoor air pollution was significantly associated with low handgrip strength among people aged 50 years and over, this suggested that ambient PM(2.5) might serve as one of the risk factors for low physical function seen in the people aged 50 years and over.

[Subjective well-being feelings and related factors in people aged 50 years or older in Shanghai: Based on Day Reconstruction Method]

Objective: To evaluate the subjective well-being feelings of people aged ≥50 years in Shanghai by using the Day Reconstruction Method (DRM) and explore the related factors. Methods: A cross-sectional survey was conducted from October 2009 to June 2010 among people aged ≥50 years selected through multistage random cluster sampling in Shanghai. DRM was used to assess participants' subjective well-being by net effect and U-index. Univariate and multivariate linear regression models were used to explore the related factors. Results: A total of 8 075 participants were included, with average age of 63.1 years. The mean net effect value was 1.24 (95%CI:1.15-1.33), and the mean U-index was 1.55% (95%CI:1.10%-1.99%). After adjusted for demographic factors, univariate liner regression model indicated that age, education level, marital status, family wealth, residence, self-rated health status, WHODAS score and prevalence of chronic disease were associated with subjective well-being, and multivariate liner regression model indicated that higher WHODAS score was associated with lower net effect value (P<0.05). Conclusion: The subjective well-being feelings of people aged ≥50 years in Shanghai might be associated with age, education level, marital status, family wealth, residence, self-rated health status and WHODAS score. Enhanced social support and appropriate social security system might facilitate the improvement of the subjective well-being of the elderly.

[Incidence of fall related injury in people aged 50 and above and risk factors in 8 provinces in China: a cross-sectional study]

Objective: To estimate the incidence and distribution characteristics of fall related injury in people aged ≥50 years in 8 provinces in China and related physiological, psychological and social risk factors. Methods: Cross-sectional data were collected from adults aged ≥50 years participating in the World Health Organization (WHO) study on global ageing and adult health (SAGE) round 1 in China. Two-level hierarchical logistic model was used to identify the related factors for fall-related injury. All the models were stratified by living area (urban/rural). Results: Estimated incidence of fall related injury (road traffic injury was not included) was 3.2%. Ageing and multiple chronic conditions (OR=2.55, 95%CI: 1.41-4.64) was significantly associated with the incidence of fall related injury in urban area. In rural area, depression (OR=4.33, 95% CI: 2.52-7.42) and multiple chronic conditions (OR=2.46, 95%CI: 1.37-4.41) were associated with the incidence of fall related injury. Conclusions: This study estimated the incidence of fall related injury in adults aged ≥50 years in 8 provinces in China. A significant association between multiple chronic conditions and fall related injury were found in both urban and rural residents. Targeted measures should be taken for the prevention and control of chronic diseases in elderly population.

[Associations of obesity and physical activity with cognition in people aged 50 and above in Shanghai]

Objective: To investigate the associations of obesity and physical activity with cognition in the elderly. Methods: A cross-sectional survey was conducted from October 2009 to June 2010 among people aged ≥50 years selected through multistage random cluster sampling in Shanghai. The subjects' body weight, body height, waist circumference and hip circumference were measured to calculate body mass index (BMI) and waist-hip ratio (WHR), and the data on self-reported physical activity level were collected through questionnaire survey. A comprehensive battery of cognitive tests was conducted to assess subjects' cognitive functions, including verbal recall, forward digit span (FDS), backward digit span (BDS), and verbal fluency (VF). General linear model was used to examine the associations of BMI, WHR and physical activity with cognition. Results: A total of 7 913 participants were included, with a median age of 60 years. Age, sex, education level, income level, BMI, WHR and physical activity level were significantly associated with cognitive scores in univariate analysis. After adjusted for age, sex, education level and income level, BMI was no longer significantly associated with cognitive scores in all cognitive functions (all P>0.01). WHR was significantly associated with VF score (P<0.01). Abdominally obese participants had lower VF score than non-abdominally obese participants (P<0.01). Physical activity level was significantly associated with all cognitive functions (P<0.01). Compared with participants with moderate physical activity level, participants with low physical activity level had lower scores in all cognitive functions (P<0.01). Conclusion: Abdominal obesity and low physical activity level were negatively associated with cognition level in the elderly, suggesting that waist circumference control and physical activity might help maintain cognition in the elderly.

[ZHENG Wenzhuo's Yi gu (Medical Original Events) and ZHANG Binglin's Yi gu mei pi qi ze (Seven Pieces of Headnotes for Yi gu)]

Yi gu (Medical Original Events) is a rare documentation science book for textual research in traditional Chinese medicine, which makes the textual research on ancient books before the Tang Dynasty by probing its provenance and development, judging the right from wrong, citing extensively with relatively reliable evidences. Actually, many items in this work were written to refute the Confucian master Yu Yue's Fei yi lun (On Abolishment of Chinese Medicine), and, to some extent, makes contributions to defend the status of traditional Chinese medicine. ZHANG Binglin, a disciple of Yu Yue, sharply accused Yi gu of textual misconducts by commenting in his Seven Pieces of Headnotes for Yi gu. It is beneficial by mutual reference and citations.

[Analysis of the patterns of female breast cancer incidence in Shanghai, 2003-2012]

Objective: To analyze the patterns of female breast cancer and their incidence in Shanghai during 2003-2012, and to compare them with international data. Methods: The data of female breast cancer cases diagnosed between 2003 and 2012 were collected from the Shanghai Cancer Registry. The record of cancer cases included the patient's name, gender, date of birth, permanent and residential address, diagnosis site or name, histological type, date of first diagnosis, diagnostic basis and diagnostic stage, etc. Data source of cancer incidence of World, Developed Countries, Developing Countries, East Asia and China in 2012 sourced from GLOBOCAN 2012 database of the WHO International Agency for Research on Cancer (IARC); and the data of USA during 2008-2012 was collected from SEER 18 database from Surveillance, Epidemiology, and End Results Program of the National Cancer Institute (NCI). Incidence indicators of Shanghai female breast cancer were calculated, including the average cases, median age, average age, proportion, crude rate, age-specific rate and age-standardized rate. Results: During 2003-2012, 41 991 new cases of female breast cancer were diagnosed in Shanghai, with an average of 4 199 cases per year, accounting for 17.23% among total new female cancer cases, ranking first in female cancer incidence in Shanghai during 2003-2012, with a crude incidence rate of 60.90 per 100 000 and an age-standardized incidence rate of 33.90 per 100 000. During 2008-2012, an average 4 528 new cases of female breast cancer was diagnosed per year in Shanghai, with 16.97% among total female cancer cases. The median age was 56 years old and the mean age was 57.73 years old. The crude rate was 64.23 per 100 000 and the age-standardized rate was 35.00 per 100 0000, which was higher than those of China (22.1 per 100 000), Eastern Areas (27.0 per 100 000) and Developing Counties (31.3 per 100 000), and lower than that of World (43.1 per 100 000), and Yellow Race Population of USA (68.77 per 100 000). During 2003-2007, on average, 3 869 new cases of female breast cancer were diagnosed per year in Shanghai, accounting for 17.54% of total female cancer cases. The median age was 53 years old and the mean age was 56.44 years old. The crude rate was 57.42 per 100 000 and the age-standardized rate was 32.69 per 100 000. There was a continuing peak stage spanned 25 years old from 50 to 74 years old, during 2008-2012. Compared with those of 2003-2007, the beginning age group of the continuing peak stage was delayed for 5 years old and the ending age group was delayed for 10 years old. Conclusion: The age-standardized incidence rate in Shanghai was higher than those of China, Eastern Areas and Developing Counties, and lower than that of World, and that of Yellow Race Population of USA; Compared with 2003-2007, the crude rate and age-standardized rate increased, the median age, mean age and the beginning and ending age group of the continuing peak stage were delayed.

[Psychopathological characteristics in patients with deviation of nasal septum: a preliminary analysis]

Objective: To investigate the psychopathological characteristics in patients with deviation of nasal septum. Methods: Between May 2015 and December 2015, fourty-four patients with deviated nasal septum and 37 patients with vocal cord polyp as control were included in this study. Psychological characteristics were evaluated by a series of questionnaire instruments including symptom checklist-90 (SCL-90), self-rating depression scale (SDS) and self-rating anxiety scale (SAS). Visual analogue scale (VAS) and rhinomanometry through front nostril were used to evaluate nasal symptom. The correlation between psychological characteristics and nasal symptom was evaluated. SPSS 20.0 software was used to analyze the data. Results: The SCL-90 score in nasal septal deviation group was 130.4±48.3. The total score and total average score of SCL-90 had no significant difference between nasal septal deviation group and the Chinese standard or control group(t value was 0.469, 0.112, 1.575, 1.564, respectively, all P>0.05). The scores of somatization, depression and anxiety factors in nasal septal deviation group were higher than control group (t value was 2.380, 2.133, 1.969, respectively, all P<0.05). The proportion of positive patients in these three factors between nasal septal deviation group and control group had significant differences (χ² value was 11.585, 9.610, 5.429, respectively, all P<0.05). The scores of SDS and SAS in nasal septal deviation group were 46.0±10.6 and 43.0±10.2, which were higher than that in the Chinese standard and control group (t value was 5.342, 6.236, 1.476, 3.013, respectively, all P<0.05). There were 9 patients companying with depression or anxiety (20.5%, 20.5%, respectively) and 5 patients companying with depression and anxiety in nasal septal deviation group (11.4%). There were positive correlation not only between the scores of SDS and the depression factor of SCL-90 but also between the scores of SAS and the anxiety factor of SCL-90 (Z=0.415, P=0.005, Z=0.445, P=0.002, respectively). The scores of SDS and SAS had positive correlation (Z=0.392, P=0.008). The VAS score of nasal obstruction was 6.0±3.2. The rhinomanometry in inspiratory and expiratory phase were (0.202±0.140) kPa·S/cm³ and (0.230±0.161) kPa·S/cm³. Besides the positive correlation between the rhinomanometry in inspiratory phase and SDS (Z=0.332, P=0.045), the psychological scores, including SCL-90 score, depression, anxiety factors score, SAS and SDS, had no correlation with VAS scores and rhinomanometry (r value was -0.030, -0.052, -0.026, 0.107, 0.185, 0.066, 0.160, 0.203, respectively, all P>0.05). Conclusions: High prevalence of depression and anxiety is found in patients with deviation of nasal septum. The SCL-90 score is consistent with SDS and SAS. Besides the positive correlation between the rhinomanometry in inspiratory phase and SDS, the psychological scores (SCL-90 score, depression, anxiety factors score, SAS and SDS) have no correlation with VAS score and rhinomanometry.

[The influence of depression degree on regulatory T cells in patients with non-M3 acute myeloid leukemia]

Objective: To investigate the influence of depression levels on regulatory T cells (Tregs) in patients with non-M3 acute myeloid leukemia (AML). Methods: A total of 63 patients with primarily diagnostic non-M3 AML and 25 healthy controls were enrolled, and the levels of depression by using HADM score and the percentages of Tregs by flow cytometry were evaluated in pre-treatment and post-treatment, respectively. Results: After every course of chemotherapy, the percentages of Tregs of PBMNC in AML showed the higher level of (6.48±1.81)% than those of (4.99±1.29)% in control (P= 0.001). There was no difference among different levels of depression groups after the first cycle. However, the percentages of Tregs increased with the worse of depression after the second and third cycles. Partial correlation analysis after adjusting age indicated that the percentages of Tregs showed no correlation with the levels of depression after the first cycle (correlation coefficient, 0.120, P=0.345), and showed the positive correlation with depression levels after the second and third cycles (correlation coefficient, 0.619 and 0.614, all P values <0.05). Conclusion: The depression levels showed an association with the percentages of Tregs in patients with non-M3 AML, which could be observed only after the second cycles of chemotherapy.

[Mutant Rad50 enhances killing effects of radiation on nasopharyngeal carcinoma cell line CNE1]

Objective: To investigate the killing effects of radiation and mutant Rad50 transfection on human nasopharyngeal carcinoma cell line CNE1. Methods: The experimental groups included: control group, Ad-Rad50-GFP group, Ad-EGFP group, irradiation group, Ad-Rad50-GFP combined with irradiation group, and Ad-EGFP combined with irradiation group. CNE1 cells were transfected with recombinant adenoviral vector Ad-Rad50-GFP carrying mutant Rad50 gene. The expressions of Mre11, Rad50, Nbs1, and relevant constituents composing MRN complex were detected by Western Blot. Neutral comet assay was used to detect the effect of mutant Rad50 on restoration process of DNA damage. Cell growth curve was used to evaluate the growth inhibition of CNE1 by mutant Rad50 and radiation. Results: Expressions of Mre11, Rad50, and Nbs1 in cells of Ad-Rad50-GFP group were less significantly than those in control group when irradiation was completed (0.48 vs 0.62, 0.42 vs 0.5, and 0.53 vs 0.69, respectively, P<0.05) and 24 hours after irradiation (0.41 vs 0.69, 0.46 vs 0.58, and 0.34 vs 0.78, respectively, P<0.05). The mean tail moment (MTM) in Ad-Rad50-GFP plus irradiation group was higher than that in irradiation group when irradiation was completed (16.06 vs 14.8, P<0.05), 24 hours after irradiation (58.23 vs 15.89, P<0.05) and 48 hours after irradiation: (45.12 vs 11.42, P<0.05). Seven days after irradiation, the cells in Ad-Rad50-GFP plus irradiation group was less than those in control group or irradiation group (both P<0.05). Conclusion: Mutant Rad50 enhances killing effects of radiation on nasopharyngeal carcinoma cell line CNE1.

[The role of textual research discipline in the formation and development of the learning of warm disease]

The theory of warm disease is basically founded in Su wen (Plain Questions) , with its basis laid down, and developed to mature in the Qing Dynasty. In addition to the developmental rules of medical science itself and the epidemics of warm disease at the turn of the Ming-Qing Dynasties, this theory rapidly developed and became an independent theory, the adoption of methodology of textual research also played an indispensable role. Specialists of warm disease sorted out, checked, and revised previous works, with discerning, annotating all terms and nomenclatures to raise questions, solvingdifficulties, strengthening the integrity, reliability, and precision of works on warm disease, thus deepened the knowledge of the nature of warm disease, promoted the formation of the specific system of diagnosis and treatment for the learning of warm disease.

Diversity and degradation mechanism of an anaerobic bacterial community treating phenolic wastewater with sulfate as an electron acceptor

Petrochemical wastewater often contains high concentrations of phenol and sulfate that must be properly treated to meet discharge standards. This study acclimated anaerobic-activated sludge to treat saline phenolic wastewater with sulfate reduction and clarified the diversity and degradation mechanism of the microbial community. The active sludge in an upflow anaerobic sludge blanket (UASB) reactor could remove 90 % of phenol and maintain the effluent concentration of SO4 (2-) below 400 mg/L. Cloning and sequencing showed that Clostridium spp. and Desulfotomaculum spp. were major phenol-degrading bacteria. Phenol was probably degraded through the carboxylation pathway and sulfate reduction catalyzed by adenosine-5'-phosphosulfate (APS) reductase and dissimilatory sulfite reductase (DSR). A real-time polymerase chain reaction (RT-PCR) showed that as phenol concentration increased, the quantities of 16S rRNA gene, dsrB, and mcrA in the sludge all decreased. The relative abundance of dsrB dropped to 12.46 %, while that of mcrA increased to 56.18 %. The change in the electron flow ratio suggested that the chemical oxygen demand (COD) was removed mainly by sulfate-reducing bacteria under a phenol concentration of 420 mg/L, whereas it was removed mainly by methanogens above 630 mg/L.

Cloning and characterization of the 5'-flanking region of the rat glutamate-cysteine ligase catalytic subunit

Glutamate-cysteine ligase (GCL), the rate-limiting enzyme in glutathione synthesis, is made up of two subunits, a catalytic (heavy) subunit (GCLC) and a modifier (light) subunit (GCLM), which are differentially regulated. Increased hepatic GCLC expression occurs during rapid growth, oxidative stress and after ethanol treatment. To facilitate studies of GCLC transcriptional regulation, we have cloned and characterized a 1.8 kb 5'-flanking region of the rat GCLC (GenBank accession number AF218362). A consensus TATA box and one transcriptional start site are located at 302 and 197 nucleotides upstream of the translational start site, respectively. The promoter contains consensus binding sites for many transcription factors including nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1). The rat GCLC promoter was able to efficiently drive luciferase expression in H4IIE cells. Sequential deletion analysis revealed that three DNA regions, -595 to -111, -1108 to -705 and -705 to -595, are involved in positive (the first two regions) and negative (the latter region) gene regulation. Specific protein binding to these regions was confirmed by DNase I footprinting and electrophoretic mobility-shift assays (EMSAs). Ethanol-fed livers exhibit increased protein binding to region -416 to -336 on DNase I footprinting analysis, which was found to be NF-kappaB and AP-1 on EMSA and supershift analysis. Acetaldehyde treatment of H4IIE cells led to a time- and dose-dependent increase in GCLC mRNA levels, binding of NF-kappaB and AP-1 to the GCLC promoter, and luciferase activity driven by the GCLC promoter fragment containing these binding sites.

Cloning and analysis of the rat glutamate-cysteine ligase modifier subunit promoter

Glutamate-cysteine ligase (GCL), the rate-limiting enzyme in glutathione (GSH) synthesis, is made up of two subunits, a catalytic (GCLC) and a modifier (GCLM) subunit, which are differentially regulated. Increased GCLM expression occurs under certain oxidative stress conditions. To facilitate studies of GCLM transcriptional regulation, we have cloned and characterized a 1.86-kb 5'-flanking region of the rat GCLM (GenBank Accession No. AF311745). A TATA-like element and one transcriptional start sites are located at 364 and 93 nucleotides upstream of the translational start site, respectively. The promoter contains consensus binding sites for many transcription factors including activator protein 1 (AP-1), transcription factor 11 (TCF11), heat shock transcription factor (HSF), and nuclear factor kappa B (NFkappaB). The rat GCLM promoter was able to drive efficiently luciferase expression in H4IIE cells. Sequential deletion analysis revealed DNA regions, -649 to -154 and -1251 to -649, are involved in positive and negative gene regulation, respectively. Candidate transcription factors were identified by DNase I footprinting.

The role of c-Myb and Sp1 in the up-regulation of methionine adenosyltransferase 2A gene expression in human hepatocellular carcinoma

Liver-specific and non-liver-specific methionine adenosyltransferase (MAT) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine. We showed a switch from MAT1A to MAT2A expression at the transcriptional level in human hepatocellular carcinoma (HCC) that facilitates cancer cell growth. The purpose of the present study was to better understand the molecular mechanism of increased MAT2A expression in HCC. In vitro DNase I footprinting analysis revealed two protected sites (-354 to -312 and -73 to -28) using nuclear proteins from HCC and HepG2 cells, but not normal liver. These sites are also protected in HepG2 cells on in vivo DNase I footprinting analysis. These protected sites contain consensus binding sites for c-Myb and Sp1. In HCC, the mRNA levels of c-myb and Sp1 and binding to their respective sites increased. Mutation of the c-Myb or Sp1 site reduced MAT2A promoter activity by 67% and 50%, respectively. The importance of these cis-acting elements and trans-activating factors was confirmed using heterologous promoter and expression vectors. Increased expression of c-Myb and Sp1 and binding to the MAT2A promoter contribute to transcriptional up-regulation of MAT2A in HCC.-Yang, H., Huang, Z.-Z., Wang, J., Lu, S. C. The role of c-Myb and Sp1 in the up-regulation of methionine adenosyltransferase 2A gene expression in human hepatocellular carcinoma.

Methionine adenosyltransferase 1A knockout mice are predisposed to liver injury and exhibit increased expression of genes involved in proliferation

Liver-specific and nonliver-specific methionine adenosyltransferases (MATs) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine (AdoMet), the principal biological methyl donor. Mature liver expresses MAT1A, whereas MAT2A is expressed in extrahepatic tissues and is induced during liver growth and dedifferentiation. To examine the influence of MAT1A on hepatic growth, we studied the effects of a targeted disruption of the murine MAT1A gene. MAT1A mRNA and protein levels were absent in homozygous knockout mice. At 3 months, plasma methionine level increased 776% in knockouts. Hepatic AdoMet and glutathione levels were reduced by 74 and 40%, respectively, whereas S-adenosylhomocysteine, methylthioadenosine, and global DNA methylation were unchanged. The body weight of 3-month-old knockout mice was unchanged from wild-type littermates, but the liver weight was increased 40%. The Affymetrix genechip system and Northern and Western blot analyses were used to analyze differential expression of genes. The expression of many acute phase-response and inflammatory markers, including orosomucoid, amyloid, metallothionein, Fas antigen, and growth-related genes, including early growth response 1 and proliferating cell nuclear antigen, is increased in the knockout animal. At 3 months, knockout mice are more susceptible to choline-deficient diet-induced fatty liver. At 8 months, knockout mice developed spontaneous macrovesicular steatosis and predominantly periportal mononuclear cell infiltration. Thus, absence of MAT1A resulted in a liver that is more susceptible to injury, expresses markers of an acute phase response, and displays increased proliferation.

Role of promoter methylation in increased methionine adenosyltransferase 2A expression in human liver cancer

Methionine adenosyltransferase (MAT), an essential enzyme that catalyzes the formation of S-adenosylmethionine (SAM), is encoded by two genes, MAT1A (liver-specific) and MAT2A (non-liver-specific). We showed a switch from MAT1A to MAT2A expression in human liver cancer, which facilitates cancer cell growth. The present work examined the role of methylation in MAT2A transcriptional regulation. We found that the human MAT2A promoter is hypomethylated in hepatocellular carcinoma, in which the gene is upregulated transcriptionally, but hypermethylated in normal liver, in which the gene is minimally expressed. Luciferase activities driven by in vitro methylated MAT2A promoter constructs were 75-95% lower than activities driven by unmethylated constructs. SAM treatment of Hep G2 cells reduced MAT2A endogenous expression by 75%, hypermethylated the MAT2A promoter, and reduced luciferase activities driven by MAT2A promoter constructs by 65-75% while not affecting MAT1A's promoter activity. Treatment of adult rat and human hepatocytes with trichostatin A, an inhibitor of histone deacetylase, upregulated MAT2A expression by more than fourfold. Collectively, these results suggest that MAT2A expression is regulated by promoter methylation and histone acetylation.

The role of c-Myb in the up-regulation of methionine adenosyltransferase 2A expression in activated Jurkat cells

Methionine adenosyltransferase (MAT) is a critical cellular enzyme which catalyses the formation of S-adenosylmethionine (SAM), the principal methyl donor. In mammals, two different genes, MAT1A and MAT2A, encode liver-specific and non-liver-specific MATs, respectively. SAM level increases during T-lymphocyte activation and is required for proliferation. A major mechanism for the increase in SAM level is increased MAT2A transcription. In the current work we examined the molecular mechanism of increased MAT2A expression in activated Jurkat cells. Treatment of Jurkat cells with interleukin-2 (IL-2), PMA or PMA plus phytohaemagglutinin (PHA) resulted in a 2-fold increase in MAT2A mRNA levels and a 2-fold increase in luciferase activity driven by the transfected human MAT2A promoter construct -571/+60 but not -270/+60. The region -571 to -270 of the human MAT2A contains a c-Myb consensus binding site. c-Myb is known to be induced during T-lymphocyte activation and its mRNA level was increased after treatment of Jurkat cells with IL-2, PMA or PMA plus PHA. Increased nuclear binding to the MAT2A c-Myb site was confirmed on electrophoretic mobility-shift and supershift analyses. Mutation of the MAT2A c-Myb site abolished the stimulatory effect of these agents on c-Myb nuclear binding and MAT2A promoter activities. Overexpression of c-Myb increased MAT2A promoter activity by 2-fold. Dexamethasone, a known inhibitor of lymphocyte activation, blocked the effect of these agents on MAT2A expression by preventing the increase in c-Myb expression.

Mechanism and significance of increased glutathione level in human hepatocellular carcinoma and liver regeneration

Increased glutathione (GSH) level occurs early during liver regeneration and in many drug and/or radiation-resistant tumors. Whether GSH level is elevated in liver cancer is unknown. GSH levels and expression of GSH synthetic enzymes were measured in hepatocellular carcinoma (HCC) and normal liver. GSH levels doubled in HCC. The mRNA levels of g-glutamylcysteine synthetase heavy subunit (GCS-HS) and GSH synthetase (GS) doubled, whereas the expression of GCS light subunit was unchanged. Nuclear run-on assay showed that the rate of gene transcription doubled for both GCS-HS and GS. In HCC, there is increased binding to anti-oxidant response, AP-1 and NF-kB, three cis-acting elements in the 5'-flanking region of the human GCS-HS important for its transcriptional regulation. The role of GSH in cell growth was examined by using HepG2 cells. Cell GSH level was varied by treating cells with cystine (0 to 0.2 mM) with or without GSH ester or buthionine sulfoximine. Cell GSH level correlated directly with growth rate. Finally, preventing the increase in GSH after two-thirds partial hepatectomy blunted liver regeneration. Thus, GSH level is increased during liver growth as a result of up-regulation of GCS-HS and GS. This increase, in turn, facilitates growth.

Changes in methionine adenosyltransferase and S-adenosylmethionine homeostasis in alcoholic rat liver

Liver-specific and non-liver-specific methionine adenosyltransferase (MAT) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine (SAM). We previously showed that MAT2A expression was associated with more rapid cell growth. Changes in MAT expression have not been examined in animal models of alcoholic liver injury, which is the focus of the current study. After rats were fed intragastrically with ethanol and high fat for 9 wk, the mRNA level of both MAT forms doubled but only the protein level of MAT2A increased. Although liver-specific MAT activity did not change, it was 32% lower after one and 68% lower after eight weekly enteral doses of lipopolysaccharide. Hepatic levels of methionine, SAM, and DNA methylation fell by approximately 40%. c-myc was hypomethylated, and its mRNA level increased. Genome-wide DNA strand break increased. Thus in the prefibrotic stage of alcoholic liver injury, there is already a switch in MAT expression, global DNA hypomethylation, increased c-myc expression, and genome-wide DNA strand break. These changes may be important in predisposing this liver disease to malignant degeneration.

Cloning and functional characterization of the 5'-flanking region of human methionine adenosyltransferase 1A gene

Methionine adenosyltransferase (MAT) is an essential cellular enzyme which catalyses the formation of S-adenosylmethionine, the principal methyl donor and precursor for polyamines. In mammals, two different genes, MAT1A and MAT2A, encode for liver-specific and non-liver-specific MAT respectively. We previously described a switch in the MAT expression from MAT1A to MAT2A in human liver cancer, which offered the cancerous cell a growth advantage. Loss of MAT1A expression was due to lack of gene transcription. To study regulation of the MAT1A gene, we have cloned and characterized a 1.9 kb 5'-flanking region of the human MAT1A gene. One transcriptional start site, located 25 nt downstream from a consensus TATA box, was identified by primer extension and RNase protection assays. The promoter contains several consensus binding sites for CAAT enhancer binding protein (C/EBP) and hepatocyte-enriched nuclear factor (HNF), transcriptional factors important in liver-specific gene expression. The human MAT1A promoter was able to efficiently drive luciferase expression in Chang cells, a human liver cell line, but not in HeLa cells. Sequential deletion analysis of the promoter revealed two DNA regions upstream of the translational start site, -705 to -839 bp and -1111 to -1483 bp, which are involved in positive and negative gene regulation, respectively. Specific protein binding to these regions was confirmed by electrophoretic-mobility-shift and DNase I footprinting assays. Similar to the situation with the rat MAT1A, glucocorticoid treatment also increased human MAT1A expression and promoter activity in a dose- and time-dependent manner.

Effect of thioacetamide on the hepatic expression of gamma-glutamylcysteine synthetase subunits in the Rat

Glutathione (GSH) is the main nonprotein thiol important in antioxidant defense and maintenance of the intracellular redox state. A major determinant of the rate of GSH synthesis is the activity of the rate-limiting enzyme, gamma-glutamylcysteine synthetase (GCS). A heavy (HS) and light subunit (LS) make up GCS; oxidative stress regulates both transcriptionally. cis-Acting elements important for the oxidative stress-induced transcriptional up-regulation of both subunits are antioxidant response element (ARE) and activator protein-1 (AP-1) site. The nuclear factor-kappaB (NF-kappaB) binding site may also regulate the heavy subunit. Increased GSH and gamma-glutamyltranspeptidase are often observed in preneoplastic hepatocyte nodules and may be important in hepatocarcinogenesis. The current work examined the effect of a commonly used hepatocarcinogen, thioacetamide (TAA), on the expression of GCS subunits. After 3 weeks of TAA treatment, liver GSH level remained unchanged despite significant oxidative stress as measured by the thiobarbituric acid reactive substance assay. The mRNA levels of GCS-HS and GCS-LS increased six- and fourfold, respectively, and the protein level of GCS-HS and GCS activity all increased. Electrophorectic mobility shift assay showed binding to ARE, AP-1, and NF-kappaB probes all increased. These results suggest TAA treatment increased hepatic GCS subunit expression and GCS activity by inducing oxidative stress and increasing the binding to redox-sensitive cis-acting elements important for transcriptional up-regulation of GCS. This is the first in vivo study that examined the effect of a hepatocarcinogen on GCS expression.

Regulation of gamma-glutamylcysteine synthetase subunit gene expression in retinal Müller cells by oxidative stress

PURPOSE

To study regulation of gamma-glutamylcysteine synthetase (GCS) heavy and light subunit gene expression in Müller cells under conditions of oxidative stress.

METHODS

Experiments were carried out with an SV40 transformed cell line (rMC-1) that exhibits the phenotype of rat retinal Müller cells. Endogenous glutathione levels were modified by treating cells with diethyl maleate (DEM), D,L-buthionine sulfoximine (BSO), or tert-butylhydroquinone (TBH). In other experiments, cells were grown in either high (28 mM) or normal (5.5 mM) glucose medium for 1 week to examine the effects of hyperglycemia. Cells were processed for reduced glutathione (GSH) measurement, RNA extraction, cell count, and, in some cases, lactate dehydrogenase activity. The steady state mRNA levels of GCS heavy and light subunits were measured by northern blot analysis using specific cDNA probes. Changes in mRNA levels were normalized to beta-actin or 18S rRNA.

RESULTS

Treatment with DEM for 30 minutes depleted cell GSH to 20% to 30% of the normal value. GSH content recovered completely 6 hours after returning to normal medium. BSO treatment for 12 hours followed by a medium change for 6 hours resulted in a cell GSH level that was 26% that of untreated cells. If cells were left in BSO for 18 hours, however, GSH levels were reduced to < 1%. Treatment with TBH for 12 hours led to a 77% increase in cellular GSH level. Treatment with DEM, TBH, or BSO for 18 hours led to a significant induction of the mRNA level of the GCS subunits, regardless of glucose concentration in the medium. Shorter BSO treatment exerted no effect. Prolonged hyperglycemia resulted in 30% lower GSH level, 55% lower GCS heavy subunit, and 30% lower GCS light subunit mRNA levels.

CONCLUSIONS

Oxidative stress induced the gene expression of GCS heavy and light subunits in Müller cells. The effect of BSO on mRNA levels correlated with the degree of GSH depletion. Prolonged hyperglycemia lowered GCS subunit mRNA and GSH levels.

Effect of ethanol and high-fat feeding on hepatic gamma-glutamylcysteine synthetase subunit expression in the rat

Glutathione (GSH) is important in antioxidant defense. A major determinant of the rate of GSH synthesis is the activity of the rate-limiting enzyme, gamma-glutamylcysteine synthetase (GCS). A heavy (HS) and light subunit (LS) make up GCS; oxidative stress regulates both transcriptionally. Cis-acting elements important for the oxidative stress-induced transcriptional up-regulation of both subunits are antioxidant response element (ARE) and activator protein-1 (AP-1). Nuclear factor-kappaB (NF-kappaB) may also regulate the heavy subunit. Chronic ethanol ingestion causes oxidative stress, increases AP-1 expression, and depletes hepatic GSH. Data conflict regarding GSH synthesis and are lacking regarding GCS subunit gene expression. We examined the effect of chronic ethanol ingestion on ARE, AP-1, and NF-kappaB activity and GCS subunit expression. Male Wistar rats were fed an ethanol and high-fat (28.7% cal) diet intragastrically for 9 weeks. Liver GSH level fell by 40%, although GCS activity doubled. GCS-HS mRNA level doubled, whereas GCS-LS mRNA level remained unchanged. Electrophoretic mobility shift assay (EMSA) showed that binding to ARE, AP-1, and NF-kappaB probes all increased. In conclusion, chronic ethanol ingestion increased GCS-HS expression and GCS activity by activating cis-acting elements important for transcriptional up-regulation of GCS-HS. GCS-LS mRNA level remained unchanged despite activation of ARE and AP-1, suggesting that negative transcriptional factors may be involved or the mRNA may be unstable. Despite induction in GCS activity, GSH level fell because of alterations in the other factors important in determining the steady-state GSH level.

Differential effect of thioacetamide on hepatic methionine adenosyltransferase expression in the rat

Liver-specific and non-liver-specific methionine adenosyltransferase (MAT) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine (SAM), the principal methyl donor. Mature liver expresses mainly MAT1A. We showed a switch from MAT1A to MAT2A gene expression in human liver cancer cells that may offer a growth advantage. To gain a better understanding of the chronology and significance of the change in MAT expression, we examined changes in hepatic MAT expression after acute treatment of rats with a hepatocarcinogen, thioacetamide (TAA). TAA treatment for 3 weeks did not change the MAT1A mRNA level but reduced the liver-specific MAT protein level to below 30% of control. TAA also acutely reduced the activity of liver-specific MAT when added to normal liver homogenates. In contrast, both the mRNA and protein levels of non-liver-specific MAT were induced. Because liver-specific MAT exhibits a much higher Km for methionine (mmol/L) than non-liver-specific MAT ( approximately 10 micromol/L), MAT activity was decreased at 5 mmol/L but increased at 20 micromol/L methionine concentration. The SAM level, SAM-to-S-adenosylhomocysteine (SAH) ratio, and DNA methylation all fell during treatment. In summary, TAA treatment induced differential changes in hepatic MAT expression. The reduction in liver-specific MAT protein level represents a novel mechanism of inactivation of liver-specific MAT. This along with induction in MAT2A contributed to a fall in the SAM-to-SAH ratio. The resulting DNA hypomethylation may be important in the process of hepatocarcinogenesis.

Cloning and functional characterization of the 5'-flanking region of human methionine adenosyltransferase 2A gene

Methionine adenosyltransferase (MAT) is a critical cellular enzyme which catalyzes the formation of S-adenosylmethionine, the principal methyl donor. In mammals, two different genes, MAT1A and MAT2A, encode for liver-specific and non-liver-specific MAT, respectively. We have cloned and characterized a 1.4-kb 5'-flanking region of the human MAT2A (GenBank Accession No. AF039088). Two major transcriptional start sites were identified by primer extension and S1 nuclease protection analysis; one was within 10 nucleotides downstream and the other was located at 158 nucleotides upstream from the consensus TATA box, respectively. The promoter is highly GC rich (75%) in the first 300 base pairs and contains several Sp-1 binding sites, a C/EBP, a HSF2, a STATx, a c-Myb, several v-Myb, and numerous GATA consensus binding sites. The human MAT2A promoter was able to efficiently drive luciferase expression in both Jurkat and 293 cells, but sequential deletion analysis of the promoter revealed that different regions of the promoter are important for cell-specific MAT2A expression.

Changes in methionine adenosyltransferase during liver regeneration in the rat

Liver-specific and non-liver-specific methionine adenosyltransferase (MAT) are products of two genes (MAT1A and MAT2A, respectively) that catalyze the formation of S-adenosylmethionine (SAM), the principal methyl donor. We previously showed that MAT2A expression was associated with more rapid cell growth. Here we examined changes in hepatic MAT gene expression and related consequences after two-thirds partial hepatectomy (PH) in rats. The mRNA levels of both MAT forms increased from 3 to 6 h, but the MAT1A level then fell below baseline from 12 to 24 h, whereas the MAT2A level remained elevated up to 4 days after PH. The increase in the MAT2A mRNA level was due to increased gene transcription and mRNA stabilization. The change in the MAT1A mRNA level was posttranscriptional and did not require de novo protein synthesis. Changes in MAT activity were consistent with an increased amount of MAT isozymes. SAM levels, the ratio of SAM to S-adenosylhomocysteine (SAH), and DNA methylation fell from 6 to 24 h, whereas SAH levels increased slightly at 12 and 24 h after PH. Both increased SAM utilization and MAT2A gene expression likely contributed to the fall in SAM.

Changes in glutathione homeostasis during liver regeneration in the rat

We have shown previously that plating primary cultures of rat hepatocytes under low density, which stimulates hepatocytes to shift from the G0 to the G1 phase of the cell cycle, resulted in increased levels of glutathione (GSH) and cysteine, and increased activity of gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in GSH synthesis (Lu et al., Am. J. Physiol. 1992;263:C1181-C1189). In the current work we examined changes in GSH homeostasis after two-thirds partial hepatectomy (PH). Male Sprague-Dawley rats underwent two-thirds PH or sham operation. GSH, oxidized glutathione (GSSG), cysteine, GSH efflux, DNA synthesis, changes in GCS subunit messenger RNA (mRNA), and protein levels were measured 12 and 24 hours after PH. Both liver GSH and cysteine levels were doubled at 12 hours and remained elevated at 24 hours after PH. GSSG levels also increased, but the ratio of GSH to GSSG levels remained unchanged. The increase in GSH and cysteine levels preceded the increase in DNA synthesis. Sinusoidal GSH efflux was unchanged after two-thirds PH, but biliary GSH efflux decreased. However, total GSH efflux was minimally altered after two-thirds PH. The increase in GSH can be largely accounted for by the increase in both cysteine availability and the activity of GCS. The steady-state mRNA and protein levels of the GCS heavy subunit were increased at 12 hours after PH. The mRNA level of the GCS light subunit was unchanged. In summary, early in the course of liver regeneration the steady-state hepatic GSH levels double because of an increase in the biosynthesis of GSH.

Differential regulation of gamma-glutamylcysteine synthetase heavy and light subunit gene expression

gamma-Glutamylcysteine synthetase (GCS) is the rate-limiting enzyme in the biosynthesis of glutathione and is composed of a heavy and a light subunit. Although the heavy subunit is enzymically active alone, the light subunit plays an important regulatory role by making the holoenzyme function more efficiently. In the current study we examined whether conditions which are known to influence gene expression of the heavy subunit also influence that of the light subunit, and the mechanisms involved. Treatment of cultured rat hepatocytes with hormones such as insulin and hydrocortisone, or plating hepatocytes under low cell density increased the steady-state mRNA level of the heavy subunit only. Treatment with diethyl maleate (DEM), buthionine sulphoximine (BSO) and t-butylhydroquinone (TBH) increased the steady state mRNA level and gene transcription rates of both subunits. These treatments share in common their ability to induce oxidative stress and activate nuclear factor kappa B (NF-kappa B). Treatment with protease inhibitors 7-amino-1-chloro-3-tosylamido-2-heptanone (TLCK) or L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK) had no influence on the basal NF-kappa B and GCS subunit mRNA levels, but blocked the activation of NF-kappa B by DEM, BSO and TBH, and the increase in GCS heavy subunit mRNA level by BSO and TBH. On the other hand, the DEM-, BSO- and TBH-induced increase in GCS light-subunit mRNA level was unaffected by TLCK and TPCK. Thus only the heavy subunit is hormonally regulated and growth sensitive, whereas both subunits are regulated by oxidative stress. Signalling through NF-kappa B is involved only in the oxidative-stress-mediated changes in the heavy subunit gene expression.

Regulation of gamma-glutamylcysteine synthetase by protein phosphorylation

We previously reported that the activity of gamma-glutamylcysteine synthetase (GCS; EC 6.3.2.2), the rate-limiting enzyme in GSH synthesis, can be acutely inhibited approximately 20-40% by agonists of various signal transduction pathways in rat hepatocytes [Lu, Kuhlenkamp, Garcia-Ruiz and Kaplowitz (1991) J. Clin. Invest. 88, 260-269]. We have now examined the possibility that GCS is phosphorylated directly by activation of protein kinase A (PKA), protein kinase C (PKC) and Ca2+/calmodulin-dependent kinase II (CMK). Phosphorylation of GCS was studied using both purified rat kidney GCS and cultured rat hepatocytes by immunoprecipitating the reaction product with specific rabbit anti-(rat GCS heavy subunit) (anti-GCS-HS) antibodies. All three kinases, PKA, PKC and CMK, phosphorylated rat kidney GCS-HS in a Mg(2+)-concentration-dependent manner, with the highest degree of phosphorylation occurring at 20 mM Mg2+. The maximum incorporation of phosphate in mol/mol of GCS was 1.17 for PKA, 0.70 for PKC and 0.62 for CMK. The degree of phosphorylation was correlated with the degree of loss of GCS activity, and no additional inhibition occurred when GCS was phosphorylated by all three kinases, suggesting that the kinases phosphorylated the same site(s). Phosphoamino analysis showed that all three kinases phosphorylated serine and threonine residues. Two-dimensional phosphopeptide mapping demonstrated that all three kinases phosphorylated the same five peptides, both PKA and PKC phosphorylated two other peptides, and only PKA phosphorylated one additional peptide. Phosphorylation of GCS decreased its Vmax for cysteine and glutamate without changing its K(m). Finally, treatment of cultured rat hepatocytes with dibutyryl cAMP and phenylephrine significantly increased the phosphorylation of GCS, suggesting a potentially important physiological role. In summary, we have demonstrated that GCS is phosphorylated and suggest that phosphorylation/dephosphorylation may regulate GCS activity.

Atherogenic and anti-atherogenic factors in the human diet

New atherosclerosis causative factors and preventive modalities have been identified. Atherogenic factors include lipid oxidation products, such as cholesterol oxidation products, malonaldehyde and other aldehydes; trans-fatty acids; some saturated fatty acids (lauric, myristic and possibly palmitic acids); and myristic acid plus cholesterol. Lipid oxidation products are well suited to induce arterial damage, based on their known cytotoxic effects; evidence also indicates the possibility of plaque promotion and stimulation of thrombogenesis. Anti-atherogenic factors include antioxidants, fish oils and other polyunsaturates (if protected from oxidation), fibre and trace minerals such as copper, manganese, selenium and zinc. Iron is unique, being considered as both a potential promoter of atherosclerosis (component of ferritin, conceivably inducing lipid oxidation) and a possible anti-atherogenic component (of antioxidant enzyme catalase). It is apparent that an entire new series of research challenges has been uncovered.