[Effects of Soil Texture on Autotrophic CO2 Fixation Bacterial Communities and Their CO2 Assimilation Contents].

Autotrophic bacteria can assimilate atmospheric carbon dioxide (CO2) and convert CO2 into organic carbon. The CO2 fixation by autotrophic bacteria is important for the improvement of carbon sequestration in agricultural soils. However, the effect of soil texture on autotrophic CO2 fixation bacteria and their CO2 fixation capacity is still unknown. Here, two paddy soils with different textures (loamy clay soil and sand clay loam soil) were incubated with continuous 14C-CO2 in a glass chamber. The two soils were developed from the same parent. At the end of 110 days incubation, the 14C-CO2 incorporated in soil organic carbon (14C-SOC), microbial biomass carbon (14C-MBC) and dissolved organic carbon (14C-DOC) were measured to explore the effects of soil texture on the autotrophic bacterial CO2 fixation rates. The effect of soil texture on the composition and diversity of autotrophic CO2 fixation bacterial community was investigated using cloning and sequencing of the cbbL gene, which encodes ribulose-1,5-biphosphate carboxylase/oxygenase (RubisCO) in the Calvin cycle. The results showed that the average contents of 14C-SOC, 14C-MBC and 14C-DOC were 133.81, 40.16 and 8.10 mg·kg-1 in loamy clay soil, respectively, which were significantly higher than their corresponding contents in sand clay loam soil (P<0.05). This suggested that soil texture not only affected the amounts of autotrophic bacteria CO2 fixation but also had an effect on the transformation of microbial assimilated 14C in soil. The cbbL gene libraries of two soils were significantly different as revealed by libshuff analyses (P<0.05). Phylogenetic analysis showed that cbbL sequences from the loamy clay soil were closely affiliated with known cultures such as Rhodoblastus acidophilus, Blastochloris viridis, Thauera humireducens, Mehylibium sp.and Variovorax sp., whereas these sequences belonging to the sand clay loam soil were related to branching lineages originating from Rhizobiales and Actinomycetales.Rarefaction curve, clone library coverage and diversity index analysis based on bacterial cbbL clone libraries indicated that the loamy clay soil had higher cbbL gene diversity compared to the sand clay loam soil. These results suggested that soil texture had a pronounced effect on the composition and diversity of autotrophic CO2 fixation bacterial communities. The higher clay content, nutrient availability and cation exchange capacity may stimulate the growth and activity of autotrophic bacteria, and result in the higher amounts of 14C in loamy clay soil. These data broaden the understanding and knowledge of mechanisms of microbial carbon fixation and their influencing factors in agricultural soils.

Association of Salivary Helicobacter pylori Infection with Oral Diseases: a Cross-sectional Study in a Chinese Population.

OBJECTIVE: The aim of this study was to detect the prevalence of oral H.pylori among adults and to investigate the correlation between H.pylori infection and common oral diseases. STUDY DESIGN: A cross-sectional study was performed among adults Chinese who took their annual oral healthy examination at The First Affiliated Hospital, Zhejiang University School of Medicine, China. RESULTS: The study included 1050 subjects in total and oral H.pylori infection occurred in 60.29% of the subjects. The prevalence rates of oral H.pylori in patients with periodontal diseases (63.42%) and caries (66.91%) were significantly increased than those without oral diseases (54.07%), respectively (P < 0.05), while the difference between subjects with recurrent aphthous stomatitis and controls was not significant. In addition, the differences of positive rates of H.pylori with or without history of gastric ulcer were statistically significant (69.47% vs 58.26%, P<0.05). Presenting with periodontal diseases (OR 1.473;95% CI 1.021 to 2.124), caries (OR 1.717; 1.127 to 2.618), and having history of gastric ulcer (OR 1.631; 1.164 to 2.285) increased the risk of H.pylori infection. CONCLUSIONS: Oral H.pylori infection is common in adult Chinese, which is significantly associated with oral diseases including periodontal diseases and caries.

[T lymphocyte subgroups and serum levels of trace elements in patients with diarrhea type of irritable bowel syndrome].

OBJECTIVE: To investigate the T lymphocyte subgroups and the levels of serum zinc (Zn), selenium (Se), iron (Fe), copper (Cu) in patients with diarrhea type of irritable bowel syndrome (D-IBS). METHODS: A total of 30 D-IBS patients and 30 control subjects were enrolled in this study, and their peripheral blood samples were collected. The percentage of peripheral CD3, CD4, CD8 T lymphocytes were analyzed by flow cytometry, and the ratio of CD4/CD8 was calculated. Serum Zn, Fe and Cu levels were determined by atomic absorption spectrometry(AAS), and the Se level by atomic fluorometry. RESULT: Compared with control group,the percentage of CD4 T lymphocyte and the ratio of CD4/CD8 in D-IBS group were significantly lower (P<0.01). However, there was no significant difference in serum Zn, Se, Fe, Cu levels between two groups (P>0.05). CONCLUSION: The declines of peripheral blood CD4 T lymphocytes and the ratio of CD4/CD8 may suggest a cellular immune abnormality in D-IBS patients. There was no significant difference in trace elements levels between the two groups.

Effect of drug treatment on hyperplastic gastric polyps infected with Helicobacter pylori: a randomized, controlled trial.

AIM: To study the effects of drug treatment on hyperplastic gastric polyps infected with Helicobacter pylori (H pylori). METHODS: Forty-eight patients with hyperplastic gastric polyps (3-10 mm in diameter) infected with H pylori were randomly assigned to a treatment group (n = 24) which received proton-pump inhibitor (omeprazole or lansoprazole), clarithromycin, bismuth citrate and tinidazole, and a control group (n = 24) which received protective agent of gastric mucosa (tepretone). Patients underwent endoscopy and H pylori examination regularly before enrollment and 1-12 mo after treatment. RESULTS: Twenty-two patients in the treatment group and 21 in the control group completed the entire test protocol. In the treatment group, polyps disappeared 1-12 mo (average, 6.5+/-1.1 mo) after the treatment in 15 of 22 patients (68.2%) and H pylori infection was eradicated in 19 of the 22 patients (86.4%). However, 12 months after the study, no change in polyps or H pylori status was seen in any controls ((b)P<0.01). CONCLUSION: Most hyperplastic gastric polyps disappear after eradication of H pylori.