Adherent properties of Helicobacter pylori to human epithelial cells *

AIM To study the properties and factors of Helicobacter pylori adherence to human epithelial cells. METHODS The adherent properties of human epithelial cells were studied by using a group of isolated H. pylori strains, anti H. pylori monoclonal antibodies and varied pH environment in in vitro adherence model with HEp 2 cell.

以退为进,将“错”就“错”——浅谈中学化学课堂教学中“错误”的利用

在课堂教学中,错误总是不可避免要发生的。如果教师仅仅是消极地予以纠正,虽然不会造成很大的负面影响,但总是会留下一点瑕疵;相反,如果教师愿意积极地开动脑筋,做点文章,也许这个错误就变成了难得的机会,可以为课堂增添意想不到的效果。

A non-invasive method for gastrointestinal parameter monitoring

AIM: To propose a new, non-invasive method for monitoring 24-h pressure, temperature and pH value in gastrointestinal tract.METHODS: The authors developed a miniature, multifunctional gastrointestinal monitoring system, which comprises a set of indigestible biotelemetry capsules and a data recorder.The capsule, after ingested by patients, could measure pressure, temperature and pH value in the gastrointestinal tract and transmit the data to the data recorder outside the body through a 434 MHz radio frequency data link. After the capsule passed out from the body, the data saved in the recorder were downloaded to a workstation via a special software for further analysis and comparison.RESULTS: Clinical experiments showed that the biotelemetry capsules could be swallowed by volunteers without any difficulties. The data recorder could receive the radio frequency signals transmitted by the biotelemetry in the body. The biotelemetry capsule could pass out from the body without difficulties. No discomfort was reported by any volunteer during the experiment. In vivo pressure and temperature data were acquired.CONCLUSION: A non-invasive method for monitoring 24-h gastrointestinal parameters was proposed and tested by the authors. The feasibility and functionality of this method are verified by laboratory tests and clinical experiments.

Thresholds of gastroesophagea reflux i the diagnosis of esophageal reflux diseases

AIMS To establish optimal thresholds of pH variation(pH fluc- tuations and reflux episodes)in separating physiological and pathological gastroesophageal reflux(GER),and to evaluate their significance in the diagnosis of GER disease. METHODS Twenty-four-hour intraesophageal pH monitoring and endoscopy were performed in 400 patients with GER symptoms and in 100 healthy controls. RESULTS The results showed that the percentages of the time with pH fluctuations in patients with and without esophagitis,and in healthy controls were,on average,12.65%,9.5% and 2. 76% in 24h,respectively,and the respective percentages of the time with reflux episodes in the same groups in 24h were,on average,3.12%,2.04% and 0.18%,respectively.Using a receiver-operating-characteristic curve analysis,<6.7% of the time with pH fluctuations and<0.1% of the time with reflux episodes were defined as the combined thresholds for physiologi- cal versus pathological reflux.The sensitivity of the combuned thresholds for the detection of GER patients with and without esophagitis was 96.7% and 90.0%,respectively,and their specificity for the diagnosis of patients with abnormal GER disease was 100%. CONCLUSIONS pH flucuations and reflux episodes,when e- valuated together,are more useful for classifying patients with GER and their combined thresholds yield higher diagnostic accura- cy in assessing patients with GER disease.

Study of influence of hiatus hernia on gastroesophageal reflux

AIM To explore whether the presence of a sliding hiatus hernia influences gastroesophageal reflux.

Influence of Environmental Conditions on Morphogenesis and on Changes of Primary and Secondary Metabolites in Asclepias syriaca L, Derived in Vitro

The object of this study was to adapt in vitro system for morphogenesis and regeneration of microshoots of common milkweed （Asclepias syriaca L.） applying different concentrations of hydrogen ion （H＋） and cytokinin 6-benzylaminopurine （BAP）. The influence of BAP and hydrogen ion （H＋） on the level of primary （chlorophyll a, chlorophyll b and carotenoids） and secondary （flavonoids and hydrolyzable and condensed tannins） metabolites in in vitro grown Asclepias syriaca L, were evaluated. Six different concentrations of BAP （0, 1, 2, 3, 4 and 5 ~tmol/L） and three different concentrations of hydrogen ion （pH 4.5, 5.0 and 5.5） were applied to the woody plant medium （WPM） medium used for microshoots propagation. The most effective morphogenesis of Asclepias syriaca L. was observed in culture medium supplemented with 2 p, mol/L BAP. However, synthesis of primary and secondary metabolites was the most intensive when cytokinin concentration reached the value of 3 gmol/L BAP. It was determined that the activity of hydrogen ion （H＋）, measured as the pH of culture medium, had a significant effect on secondary metabolites in the shoots in vitro.

Determination of Boron Trifluoride in Boron Trifluoride Complex by Fluoride Ion Selective Electrode

A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain p H value was limited and hardly related to F-concentration and boric acid. It is better to control p H value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 ℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

Combined effects of water temperature and copper ion concentration on catalase activity in Crassostrea ariakensis

A central composite experimental design and response surface method were used to investigate the combined effects of water temperature(18–34℃) and copper ion concentration(0.1–1.5 mg/L) on the catalase(CAT) activity in the digestive gland of C rassostrea ariakensis. The results showed that the linear effects of temperature were significant(P <0.01), the quadratic effects of temperature were significant( P <0.05), the linear effects of copper ion concentration were not significant(P >0.05), and the quadratic effects of copper ion concentration were significant(P <0.05). Additionally, the synergistic effects of temperature and copper ion concentration were not significant(P >0.05), and the effect of temperature was greater than that of copper ion concentration. A model equation of CAT enzyme activity in the digestive gland of C. ariakensis toward the two factors of interest was established, with R 2, Adj. R 2 and Pred. R 2 values as high as 0.943 7, 0.887 3 and 0.838 5, respectively. These findings suggested that the goodness of fit to experimental data and predictive capability of the model were satisfactory, and could be practically applied for prediction under the conditions of the study. Overall, the results suggest that the simultaneous variation of temperature and copper ion concentration alters the activity of the antioxidant enzyme CAT by modulating active oxygen species metabolism, which may be utilized as a biomarker to detect the effects of copper pollution.

A first-principles study of site occupancy and interfacial energetics of an H-doped TiAl-Ti_3 Al alloy

We investigate the site occupancy and the interfacial energetics of TiAl-Ti3Al binary-phase system with H using a first-principles method. H energetically prefers to occupy the Ti-rich octahedral interstitial site because H prefers to bond with Ti rather than with Al. The occupancy tendency of H in the binary phase TiAl-Ti3Al alloy from high to low is α2-Ti3Al to γ/α2 interface and 7-TiAl, because the decrease of the Ti local concentration is in the same order. We demonstrate that H can largely affect the mechanical properties of the TiAl-Ti3Al system. On the one hand, H at the interface reduces the interface energy with the H2 molecule as a reference, implying the TiAl/Ti3Al interface is stabilized. On the other hand, the ratio between the cleavage energy and the unstable stacking fault energy decreases after H-doping, indicating H will reduce the ductility of the TiAl/Ti3Al interface. Consequently, the mechanical property variation of TiA1 alloy due to the presence of H not only depends on the amount of TiAl/Ti3Al interfaces but also is related to the H concentration in the alloy.