Clinical guideline on magnetically controlled capsule gastroscopy (2021 edition).

With the development and generalization of endoscopic technology and screening, clinical application of magnetically controlled capsule gastroscopy (MCCG) has been increasing. In recent years, various types of MCCG are used globally. Therefore, establishing relevant guidelines on MCCG is of great significance. The current guidelines containing 23 statements were established based on clinical evidence and expert opinions, mainly focus on aspects including definition and diagnostic accuracy, application population, technical optimization, inspection process, and quality control of MCCG. The level of evidence and strength of recommendations were evaluated. The guidelines are expected to guide the standardized application and scientific innovation of MCCG for the reference of clinicians.

Changing patterns of the East Asian monsoon drive shifts in migration and abundance of a globally important rice pest.

Numerous insects including pests and beneficial species undertake windborne migrations over hundreds of kilometers. In East Asia, climate-induced changes in large-scale atmospheric circulation systems are affecting wind-fields and precipitation zones and these, in turn, are changing migration patterns. We examined the consequences in a serious rice pest, the brown planthopper (BPH, Nilaparvata lugens) in East China. BPH cannot overwinter in temperate East Asia, and infestations there are initiated by several waves of windborne spring or summer migrants originating from tropical areas in Indochina. The East Asian summer monsoon, characterized by abundant rainfall and southerly winds, is of critical importance for these northward movements. We analyzed a 42-year dataset of meteorological parameters and catches of BPH from a standardized network of 341 light-traps in South and East China. We show that south of the Yangtze River during summer, southwesterly winds have weakened and rainfall increased, while the summer precipitation has decreased further north on the Jianghuai Plain. Together, these changes have resulted in shorter migratory journeys for BPH leaving South China. As a result, pest outbreaks of BPH in the key rice-growing area of the Lower Yangtze River Valley (LYRV) have declined since 2001. We show that these changes to the East Asian summer monsoon weather parameters are driven by shifts in the position and intensity of the Western Pacific subtropical high (WPSH) system that have occurred during the last 20 years. As a result, the relationship between WPSH intensity and BPH immigration that was previously used to predict the size of the immigration to the LYRV has now broken down. Our results demonstrate that migration patterns of a serious rice pest have shifted in response to the climate-induced changes in precipitation and wind pattern, with significant consequences for the population management of migratory pests.

Comprehensive analysis of tumor necrosis factor-α-inducible protein 8-like 2 (TIPE2): A potential novel pan-cancer immune checkpoint.

Tumor necrosis factor-α-inducible protein 8-like 2 (TIPE2) is encoded by TNFAIP8L2 and is a newly identified negative regulator of natural and acquired immunity that plays a critical function in maintaining immune homeostasis. Recently, CAR-NK immune cell therapy has been a focus of major research efforts as a novel cancer therapeutic strategy. TIPE2 is a potential checkpoint molecule for immune cell maturation and antitumor immunity that could be used as a novel NK cell-based immunotherapeutic approach. In this study, we explored the expression of TNFAIP8L2 across various tumor types and found that TNFAIP8L2 was highly expressed in most tumor types and correlated with prognosis. Survival analysis showed that TNFAIP8L2 expression was predictive of improved survival in cervical-squamous-cell-carcinoma (CESC), sarcoma (SARC) and skin-cutaneous-melanoma (SKCM). Conversely, TNFAIP8L2 expression predicted poorer survival in acute myeloid leukemia (LAML), lower-grade-glioma (LGG), kidney-renal-clear-cell-carcinoma (KIRC) and uveal-melanoma (UVM). Analysis of stemness features and immune cell infiltration indicated that TNFAIP8L2 was significantly associated with cancer stem cell index and increased macrophage and dendritic cell infiltration. Our data suggest that TNFAIP8L2 may be a novel immune checkpoint biomarker across different tumor types, particularly in LAML, LGG, KIRC and UVM, and may have further utility as a potential target for immunotherapy.

Alliumheterophyllum (Amaryllidaceae), a new species from Henan, China.

Alliumheterophyllum D.F.Xie & X.J.He, sp. nov. (Amaryllidaceae), is a new species from Henan, China and is described based on morphological and molecular evidence. It is morphologically most similar to A.dumebuchum in the rhomboid scape in cross-section. However, distinctive differences were detected in perianth color, leaf shape and cross-section, flowers' density as well as flowering season. Similarly, the karyotype of A.heterophyllum is 2n = 2x = 16 and in A.dumebuchum is 2n = 4x = 32. Phylogenetic analysis based on nuclear ribosomal Internal Transcribed Spacers (ITS) and three cpDNA regions strongly supports that A.heterophyllum is a member of Allium section Rhizirideum and sister to the other species of this section (e.g. A.senescens, A.spirale, and A.prostratum). Currently, only one population and approximately 120 individuals were discovered; the development of scenic spots in this region may affect its growth and threaten this population. Therefore, this new species is preliminarily considered as Near Threatened (NT) according to criteria of the IUCN Red List.

Multi-omics analyses of tumor-associated immune-infiltrating cells with the novel immune checkpoint protein tyrosine phosphatase 1B (PTP1B) in extracellular matrix of brain-lower-grade-glioma (LGG) and uveal-melanoma (UVM).

Immune checkpoint inhibitors represented by PD-1 have greatly changed the way cancer is treated. In addition to PD-1, new immune checkpoints are constantly excavated to better treat cancer. Recently, protein tyrosine phosphatase 1B (PTP1B) was identified as a new immune checkpoint and played a critical role in the treatment of tumors by inhibiting the proliferation and cytotoxicity of T cells induced by tumor antigen. To explore the targeting role of PTP1B in precision tumor therapy, we deeply analyzed the expression and prognosis of PTP1B in all tumors. Survival analysis results indicated that PTP1B was highly expressed in most tumor tissues and indicated poor prognosis in acute-myeloid-leukemia (LAML), brain-lower-grade-glioma (LGG), kidney-renal clear-cell-carcinoma (KIRC) and uveal-melanoma (UVM). The methylation status of PTP1B in these four tumors exhibited hypomethylation and mutation landscape showed that PTP1B had its specific characteristics in genomic instability and heterogeneity. The homologous recombination deficiency (HRD) and loss of heterozygosity (LOH) were positive related to PTP1B expression in liver-hepatocellular-carcinoma (LIHC) and kidney-chromophobe (KICH), while the immunescore and immune infiltration displayed a significant positive correlation with PTP1B expression in LGG and UVM. Drug sensitivity tests showed that the PTP1B inhibitor MSI-1436 had a sensitivity effect suppressing tumor cell viability and suggested it enhanced the efficacy of PD-1 inhibitors in cancers.

A Novel Method Based on Combination of Independent Component Analysis and Ensemble Empirical Mode Decomposition for Removing Electrooculogram Artifacts From Multichannel Electroencephalogram Signals.

Electrooculogram (EOG) is one of common artifacts in recorded electroencephalogram (EEG) signals. Many existing methods including independent component analysis (ICA) and wavelet transform were applied to eliminate EOG artifacts but ignored the possible impact of the nature of EEG signal. Therefore, the removal of EOG artifacts still faces a major challenge in EEG research. In this paper, the ensemble empirical mode decomposition (EEMD) and ICA algorithms were combined to propose a novel EEMD-based ICA method (EICA) for removing EOG artifacts from multichannel EEG signals. First, the ICA method was used to decompose original EEG signals into multiple independent components (ICs), and the EOG-related ICs were automatically identified through the kurtosis method. Then, by performing the EEMD algorithm on EOG-related ICs, the intrinsic mode functions (IMFs) linked to EOG were discriminated and eliminated. Finally, artifact-free IMFs were projected to obtain the ICs without EOG artifacts, and the clean EEG signals were ultimately reconstructed by the inversion of ICA. Both EOGs correction from simulated EEG signals and real EEG data were studied, which verified that the proposed method could achieve an improved performance in EOG artifacts rejection. By comparing with other existing approaches, the EICA obtained the optimal performance with the highest increase in signal-to-noise ratio and decrease in root mean square error and correlation coefficient after EOG artifacts removal, which demonstrated that the proposed method could more effectively eliminate blink artifacts from multichannel EEG signals with less error influence. This study provided a novel promising method to eliminate EOG artifacts with high performance, which is of great importance for EEG signals processing and analysis.

A better prediction of progression-free survival in diffuse large B-cell lymphoma by a prognostic model consisting of baseline TLG and %ΔSUVmax.

In the era of rituximab, the International Prognostic Index (IPI) has been inefficient in initial risk stratification for patients with R-CHOP-treated diffuse large B-cell lymphoma (DLBCL). To estimate the predictive values of PET/CT quantitative parameters and three prognostic models consisting of baseline and interim parameters for three-year progression-free survival (PFS), we conducted an analysis of 85 patients in China with DLBCL underwent baseline and interim PET/CT scans and treated at the Department of Hematology of Peking University Third Hospital from November 2012 to November 2017. The PET/CT parameters, viz. the baseline and interim values of standardized uptake value (SUVmax ), total metabolic tumor volume (TMTV), and total lesion glycolysis (TLG), and their rates of change, were analyzed by a receiver operating characteristics curve, Kaplan-Meier analysis, and log-rank test. Besides, the National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) was also included in the multivariate Cox hazards model. Owing to the strong correlation between TMTV and TLG at baseline and interim (Pearson's correlation coefficient, r = 0.823, P-value = 0.000, and 0.988, P-value = 0.000, respectively), only TLG was included in the multivariate Cox hazards model, where TLG0  > 1036.61 g and %ΔSUVmax  < 86.02% showed predictive value independently (HR = 10.42, 95% CI 2.35-46.30, P = 0.002, and HR = 4.86, 95% CI 1.27-18.54, P = 0.021, respectively). Replacing TLG in the equation, TMTV0 and TMTV1 both showed significantly predictive abilities like TLG (HR = 8.22, 95% CI 1.86-32.24, P = 0.005, and HR = 2.96, 95% CI 1.16-7.54, P = 0.023, respectively). After dichotomy, NCCN-IPI also gave a significant performance (P = 0.035 and P = 0.010, respectively, in TLG and TMTV models). The baseline variables, that is, TMTV0 , TLG0 and dichotomized NCCN-IPI, and the interim variables TMTV1 and %ΔSUVmax , presented independent prognostic value for PFS. In prognostic model 2 (TLG0  + %ΔSUVmax ), the group with TLG0  > 1036.61 g and %ΔSUVmax  < 86.02% recognized 19 (82.6%) of the relapse or progression events, which showed the best screening ability among three models consisting of baseline and interim PET/CT parameters.

Gender differences in suicidal ideation and health-risk behaviors among high school students in Beijing, China.

BACKGROUND: Suicide is still the leading cause of death in the 15 to 34-year age group, especially for girls aging 15 to 19-year old. In China particularly, the suicide rate of female is 60% higher than male. The gender difference on suicidal ideation and its patterns with academic, family, social and health-risk factors is unknown among adolescents in Beijing, China. METHODS: A total of 33 635 students in grades 7-12 in Beijing participated in the 2014 Chinese Youth Risk Behavior Surveillance. Data were stratified by gender and associations with suicidal ideation were analyzed using χ2 test and multivariate regression analyses. The interaction effects on suicidal ideation between gender and the related behaviors were also analyzed. RESULTS: The prevalence of suicidal ideation was significantly higher for girls (13.3%) than boys (10.7%). The multivariate regression analyses indicated that high academic pressure, running away from home, feeling lonely or sad/hopeless, being bullied, fighting, and binge drinking were significantly associated with suicidal ideation in boys and girls. Factors more strongly associated with suicidal ideation in girls than boys were being in junior vs senior high school (girl vs boys: 1.24 vs NA), high academic pressure (2.42 vs 1.55), ever smoking (1.52 vs NA), binge drinking (1.30 vs 1.17), fighting once (1.63 vs 1.06) and being sad/hopeless (2.39 vs 2.04) and their interaction with gender were all statistically significant (P < 0.05). A lower likelihood of suicidal ideation was found among boys, but not girls, who had PE class two or more days per week. CONCLUSIONS: Girls showed more vulnerability to suicidal ideation than boys particularly among girls in junior school, reporting high academic pressure, smoking, binge drinking and fighting. The combinations of risk factors and differential patterns for boys and girls point to high-risk groups and potential targets for gender-specific suicide prevention.

Sphingosine kinase 1 knockout alleviates hepatic ischemia/reperfusion injury by attenuating inflammation and oxidative stress in mice.

BACKGROUND: Hepatic ischemia/reperfusion (I/R) injury remains a significant problem in clinical practice. Sphingosine kinase 1 (SphK1) phosphorylates sphingosine to sphingosine-1-phosphate (S1P) which participates in multiple bioactive processes. However, little is known about the role of SphK1 in hepatic I/R injury. This study aimed to investigate the effect of SphK1 knockout on liver I/R injury and to explore underlying mechanisms. METHODS: SphK1 knockout and wild type mice were subjected to 70% partial hepatic I/R. Serum alanine aminotransferase was determined to indicate the degree of liver damage. Hematoxylin-eosin staining and TUNEL assay were used to assess histological changes and hepatocellular apoptosis, respectively. Immunohistochemistry was performed to detect the expression and translocation of phosphorylated p65 and signal transducer and activator of transcription 3 (STAT3). Western blotting was used to determine the expression of S1P receptor 1 (S1PR1), phosphorylated p65 and STAT3. Real-time PCR was used to demonstrate the changes of proinflammatory cytokines. Oxidative stress markers were also determined through biochemical assays. RESULTS: SphK1 knockout significantly ameliorated I/R-induced liver damage, mitigated liver tissue necrosis and apoptosis compared with wild type control. I/R associated inflammation was alleviated in SphK1 knockout mice as demonstrated by attenuated expression of S1PR1 and reduced phosphorylation of nuclear factor kappa B p65 and STAT3. The proinflammatory cytokines interleukin-1ß, interleukin-6 and tumor necrosis factor-α were also inhibited by SphK1 genetic deletion. The oxidative stress markers were lower in SphK1 knockout mice after I/R injury than wild type mice. CONCLUSIONS: Knockout of SphK1 significantly alleviated damage after hepatic I/R injury, possibly through inhibiting inflammation and oxidative stress. SphK1 may be a novel and potent target in clinical practice in I/R-related liver injury.

Self-enhancement of CO reversible absorption accompanied by phase transition in protic chlorocuprate ionic liquids for effective CO separation from N2.

An efficient strategy for the high-capacity capture of CO is reported, and a phase change in protic chlorocuprate ionic liquids (PCILs) from liquid to solid is found during CO absorption. The highest CO capacity is 0.96 molCO molIL-1, being at least 150 times higher than that in [BMIM][PF6]. Both absorption and membrane permeation reveal that the PCILs are potential for the selective separation of CO from N2.

Regulation of P300 and HDAC1 on endoplasmic reticulum stress in isoniazid-induced HL-7702 hepatocyte injury.

P300 and HDAC1 can be involved in the development of various liver diseases by regulating gene transcription. Endoplasmic reticulum stress (ERS) is one of the main pathways of apoptosis and is activated during inflammatory responses, but the roles of P300 and HDAC1 in ERS in antituberculosis drug-induced liver injury (ADLI) are not clear. This study confirms that isoniazid can change the states of P300 and HDAC1 in HL-7702 hepatocyte metabolism and induce ERS, causing hepatocyte injury and apoptosis. When combined with C646, however, P300 can be reduced. HL-7702 cells were flattened, and the cytoplasm became crinkled. To a certain extent, ERS was relieved, but hepatocytes suffered worse damage, and the rate of cell apoptosis markedly increased. When MS-275 was applied, HDAC1 level was increased, cell fusion appeared, and fluorescence intensity of endoplasmic reticulum was weakened. In addition, ERS was aggravated, but liver injury was relieved, and the apoptosis rate significantly decreased. Therefore, alteration of P300 and HDAC1 status and ERS are involved in ADLI, and changes in P300 and HDAC1 can regulate ERS and then affect cell damage.

Stable Na Plating and Stripping Electrochemistry Promoted by In Situ Construction of an Alloy-Based Sodiophilic Interphase.

Sodium metal anodes are poor due to the reversibility of Na plating/stripping, which hinders their practical applications. A strategy to form a sodiophilic Au-Na alloy interphase on a Cu current collector, involving a sputtered Au thin layer, is shown to enable efficient Na plating/stripping for a certain period of time. Herein, electrochemical behaviors of Na plating on different substrates are explored, and it is revealed that the sodiophilic interphase can be achieved universally by in situ formation of M-Na (M = Au, Sn, and Sb) alloys during Na plating prior to Na bulk deposition in the initial cycle. Moreover, it is found that repetitive alloying-dealloying leads to falling-off of thin film sodiophilic materials and thus limits the lifespan of efficient Na cycling. Therefore, an approach is further developed by employing particles of sodiophilic materials combined with the control over the cutoff potential, which significantly improves the stability of Na plating/stripping process. Especially, the low-cost Cu@Sn-NPs and Cu@Sb-MPs composite current collectors allow Na plating and stripping to cycle for 2000 and 1700 times with the average efficiency of 99.9% at 2 mA cm-2 .

[Value of 18F-FDG PET/CT Scan Quantization Parameters for Prognostic Evaluation of Patients with Diffuse Large B-cells Lymphoma].

OBJECTIVE: To investigate the prognostic value of 18F-FDG PET/CT scan quantization parameters, max standardized uptake value （SUVmax）, metabolic tumor volume （MTV）, total lesion glycolysis （TLG） and other clinical factors for prognostic evaluation of paticnts with diffuse large B-cell lymphoma （DLBCL）. METHODS: PET/CT scan and clinical data of a total of 65 newly diagnosed DLBCL patients who received Rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone （R-CHOP） chemotherapy as first-line treatment were analyzed. All patients received a PET/CT scan at diagnosis and an interim PET/CT after 2-4 circles of chemotherapies. The related parameters of SUVmax, MTV and TLG were acquired by analyzing and calculating the scan results. The receiver operating characteristic （ROC） curve was used to determine the optimal cut-off of parameters. Pearson chi-square test, Kaplan-Meier method and COX proportional hazard model were performed to analyze the prognostic value of PET/CT related parameters and clinical factors in progression-free survival （PFS）. RESULTS: Age, B symptom, Ann Arbor stage and extra-nodal involvement in major organs significantly related with PFS （P<0.05）, but the SUVmax didn't relalt with the prognosis. The cut-off values of MTV0, MTV1, TLG0 and TLG1 for disease recurrence or progression were 172.20cm 3, 4.32cm 3, 1043.33g and 14.07g. The lower MTV and TLG groups showed longer PFS significantly. In the multivariate Cox regression model, B symptoms, MTV1 and TLG1 were the independent prognostic risk factors. CONCLUSION: MTV and TLG at baseline and in the interim and NCCN-IPI correlate with disease prognosis. SUVmax related parameters hare no significant relationship with prognosis. Besides MTV and TLG during treatment are the independent prognostic risk factors suggesting more predictive value than NCCN-IPI.

Involvement of histone hypoacetylation in INH-induced rat liver injury.

This study explores the mechanism of histone acetylation under the effect of oxidative stress in rat liver injury induced by isoniazid (INH). Fifty-six adult SD rats were selected and divided randomly into INH groups (48) and control (8). Rats in INH groups were intragastrically injected with 55 mg kg-1 day-1 for 3, 7, 10, 14, 21, and 28 days, and control rats were given an equal volume of distilled water. Pathological changes in liver tissues were observed by HE staining. Western blot analysis was conducted to measure the expression levels of H3k14ac and H4k8ac. The activities of HAT, HDAC and IL-1ß, and TNF-α were detected by ELISA in liver tissues. Real-time RT-PCR analysis was performed to determine the protein expression levels of HAT, HDAC, and IL-1ß and the mRNA expression of TNF-α. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were assayed by biochemical methods in liver tissues. At different time points, the SOD activity decreased, whereas the MDA content significantly increased after 14 days (FSOD = 11.15, FMDA = 7.42, P < 0.01). During this period, the expression of histone acetylated H3K14 and H4K8 acetylation decreased compared with the control group (FH3K14 = 4.18, FH4K8 = 3.87, P < 0.05); by contrast, HDAC1 and HDAC2 showed a high expression level compared with those in the control group (FHDAC1 = 29.13, FHDAC2 = 58.34, P < 0.01). Moreover, the expression of CBP/P300 was lower than that in the control group (FCBP/P300 = 12.18, P = 0.001), and the protein contents of IL-1ß and TNF-α in rat liver tissues were up-regulated (FIL-1ß = 44.88, FTNF-α = 41.56, P < 0.01). These results suggest that histone acetylation is involved in INH-induced rat liver injury. Furthermore, the hypoacetylation of histones H3K14 and H4K8 is negatively correlated with oxidative stress-mediated rat liver injury.

Dilation Time in Endoscopic Papillary Balloon Dilation for Common Bile Duct Stones.

BACKGROUND: To assess the short-term outcomes after endoscopic sphincterotomy (EST) plus endoscopic papillary balloon dilation (EPBD) versus EPBD alone and appropriate balloon dilation time in EPBD alone. MATERIALS AND METHODS: A total of 413 patients with common bile duct stones (CBDSs) were included in the EST plus EPBD group and 84 were in the EPBD alone group. We retrospectively evaluated the safety and efficacy between EST plus EPBD and EPBD alone group. The patients in EPBD alone group were assigned to dilation time ≥5 minutes group (n=35) and time <5 minutes group (n=49). Further, we preliminarily discussed the influence of balloon dilation time on the procedure-related complications. RESULTS: Compared with EST plus EPBD, the patients in EPBD alone group were younger [56.6 (range: 18 to 95) vs. 65.1 (24 to 92) y; P=0.006], had smaller diameter of the largest stone [10.4 (range: 3 to 20) vs. 12.3 (5 to 30) mm; P<0.001] and were lesser frequently performed with jaundice [22 (26.2%) vs. 189 (45.8%); P=0.001]. The mean duration of postoperative hospital stay in EPBD alone group was significantly shorter than EST plus EPBD group [6.3 (range: 1 to 18) vs. 9.2 (1 to 44) d; P<0.001]. The patients in EPBD alone group had higher risk of post endoscopic retrograde cholangiopancreatography pancreatitis than EST plus EPBD group [11 (13.1%) vs. 22 (5.3%); P=0.009]. Patients in the dilation time <5 minutes group had higher risk to suffer from postoperative pancreatitis than the EST plus EPBD group [9 (18.4%) vs. 22 (5.3%); P=0.002], while patients in the dilation time ≥5 minutes group had less procedure-related hemorrhage than the EST plus EPBD group [0 vs. 36 (8.7%); P=0.047]. CONCLUSION: Long balloon dilation time in EPBD alone is safe and effective in treating CBDSs.

[Effects of interaction of genotypes with environments on major latently fragrant substances of flue-cured tobacco in Baoshan of Yunnan, Southwest China].

To study the stability of major latently fragrant substances of flue-cured tobacco of different varieties in Baoshan of Yunnan, three tobacco cultivars (K326, Y87 and Y99) in two soil types at three test sites with different altitudes were tested. The contents of major latently fragrant substances were measured and the effects of genotypes, environments and their interactions were analyzed by AMMI model. The results showed that genotypes, environments and their interactions had significant effects on the contents of lutein, ß-carotene, and chlorogenic acid. The rutin content was mainly influenced by genotypes while the major latently fragrant substances and their stability were affected significantly by the interactions of genotypes and environments. The contents of lutein, ß-carotene, and chlorogenic acid increased remarkably with altitude, and their stabilities were strengthened to different extents. K326 adapted well to middle-lower altitude, while Y87 and Y99 adapted well to middle-higher altitude.

[Soil nutrients spatial variability and soil fertility suitability in Qujing tobacco-planting area].

By adopting GPS technique, 2088 sampling sites were installed in the tobacco-planting area of Qujing City, Yunnan Province, with 0-20 cm soil samples collected to determine their main nutrients contents. The overall characteristics and spatial variability of the tobacco soil nutrients were analyzed by classic statistics and geo-statistics, and the soil fertility suitability in planting tobacco was evaluated by the methods of fuzzy mathematics. In the study area, soil pH and soil organic matter, available S, and water-soluble Cl contents were appropriate, soil total N and alkalihydrolyzable N contents were too high, soil available K, Ca, Mg, Cu, Fe, Zn, Mo, and Mn contents were abundant, soil available P content was at medium level, while soil total P and K and available B contents were insufficient. All the nutrient indices presented anisotropic distribution, among which, the spatial variability of soil available P and B was mainly caused by random factors, and that of other nutrients was caused by the co-effects of structural and random factors. The spatial distribution map of soil fertility suitability index (SFI) showed that there was no the excellent grade region for tobacco-planting, good grade region accounted for 8.0%, general grade region accounted for 51.6%, moderate grade region accounted for 39.0%, and low grade region accounted for 1.4%.

[Regional characteristics of sulfur contents in flue-cured tobacco in Hunan Province and their influence to smoking quality].

A total of 559 flue-cured tobacco samples with 3 grades (B2F, C3F and X2F) were collected from the main tobacco-growing areas in Hunan Province, and their sulfur contents were determined to study the regional characteristics of the sulfur contents and their quantitative correlations with the evaluation indices of smoking quality. The results showed that the sulfur content in the flue-cured tobacco was 0.100%-2.106% , with a mean of 0.884%. The samples with sulfur content above 0.7% accounted for 71.56% of the total. The sulfur content decreased gradually from the high sulfur content area of Central Hunan to South Hunan and Northwest Hunan. With increasing sulfur content in tobacco leaf, the aroma quality, aftertaste, combustibility and ash color went to bad, offensive odor and irritation property increased, and aroma taste, eat-taste and total smoking quality score fell down. Under the influence of applying larger amount sulfate potassium and of sulfur-type acid precipitation, the sulfur content in tobacco leaf was somewhat higher in partial areas of Hunan Province, and gave negative impact on tobacco quality, being one of key factors limiting the improvement of tobacco quality and ought to be attached enough importance in tobacco production.