Helicobacter pylori determination in non-municipal drinking water and epidemiological findings

Background.?Studies conducted in Europe as well as in North and South America have tried to link Helicobacter pylori colonization with the drinking water supply, especially since H. pylori is known to survive quite well in water.

Methods.?In 2000, a cohort of 1884 grade-two children from two rural counties surrounding the city of Leipzig, Germany (77.4% of the 1991/1992 birth cohort) were tested for H. pylori colonization using the [¹³C]urea breath test. A parent-completed questionnaire elicited details on living conditions and lifestyle habits including questions on the children's drinking water from sources other than public water supplies, swimming in natural waters, etc.

In a second independent study, samples of well water, taken from 157 private wells still used in the two counties, were being tested for the presence of H. pylori, using polymerase chain reaction (PCR) method to determine relevant target DNA fragments of H. pylori.

Results.?In county I, 5.7% of the children and in county II 6.6% tested H. pylori-positive. Cluster analyses of the questionnaire data in both counties pointed to ‘drinking water from other than municipal sources’, as the closest H. pylori-associated cluster variable. The cluster estimations were supported by odds ratio (OR) calculations with an OR?=?16.4 (95% confidence interval (CI) 3.1,…,88.5) for county I and OR?=?4.0 (95% CI 1.3,…,12.4) for county II.

The PCR analyses showed H. pylori DNA fragments in 10.8% of the wells in county I and 9.2% in county II. The detection limit was set at 10 DNA copies corresponding to 125?bacteria/L, the average infestation of these wells was 931?bacteria/L.

Conclusion.?Despite the fact that the microbiological and epidemiological data do not correspond except that both studies were conducted in the same geographical areas, the independent findings of H. pylori in well water in the same general areas where children do seem to drink water other than from the public water supply suggests that water may be an important source of H. pylori infection.     

Simultaneous EEG-fMRI acquisition: how far is it from being a standardized technique?

Simultaneous EEG–fMRI is a powerful tool to study spontaneous and evoked brain activity because of the complementary advantages of the two techniques in terms of temporal and spatial resolution. In recent years, a significant number of scientific works have been published on this subject. However, many technical problems related to the intrinsic incompatibility of EEG and MRI methods are still not fully solved. Furthermore, simultaneous acquisition of EEG and event-related fMRI requires precise synchronization of all devices involved in the experimental setup. Thus, timing issue must be carefully considered in order to avoid significant methodological errors.

The aim of the present work is to highlight and discuss some of technical and methodological open issues associated with the combined use of EEG and fMRI. These issues are presented in the context of preliminary data regarding simultaneous acquisition of event-related evoked potentials and BOLD images during a visual odd-ball paradigm.     

Quantitative Bestimmung von DNA in Geweben durch Thymin-Analyse

Zusammenfassung Es wird über eine DNA-Bestimmung in biologischem Material durch Hochdruckflüssigkeits-Chromatographie an sphärischen Ionenaustauschern berichtet. Thymin wird durch Hydrolyse lyophilisierter Gewebe freigesetzt, durch Sublimation gereinigt und flüssigkeits-chromatographisch bei etwa 150 at Eingangsdruck bestimmt. Die Ausbeute des Verfahrens wird durch Isotopenverdünnungsanalyse überprüft. Der Einfluß von pH-Wert und Konzentration der Elutionspuffer und der Säulentemperatur wird ermittelt. Die untere quantitative Nachweisgrenze der Methode liegt bei etwa 0,5 g DNA in Geweben, die relative Standardabweichung betrug 10%.

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Quantitative determination of DNA in tissues by thymine-analysisII. Determination by high-pressure ionexchange liquid chromatography

A determination of DNA in biological material by high pressure, liquid chromatography of thymine on spherical ion-exchange resins is presented. After lyophilizing and hydrolyzing the tissues, thymine is separated by sublimation and determined by means of liquid chromatography at 150 at. Yields are controlled by isotope dilution analysis. Investigations on the effect of pH and concentration of eluents and of temperature are reported. The method is suitable for a minimal amount of 0.5 g DNA in tissues with a relative standard deviation of 10%.

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Teil I: diese Z. 259, 177 (1972).

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Geodia cydonium wurde uns dankenswerterweise von der meeresbiologischen Forschungsgruppe, Leitung Herr Prof. Dr. R. K. Zahn, zur Verfügung gestellt.     

An Analytical Method for the Separation and Determination of As(III) and As(V) in Seepage and Acid Mine Drainage Water

To avoid changes in the original As species distribution in natural water after sampling, a method of immediate separation of As(V) by anion exchange at the sampling site was developed. The procedure consists of two steps. The total concentration of arsenic is determined in one part of the water sample acidified on site. Another part of the water samples is pressed through a column filled with an anion exchanger. The As(III) species that is not redox-stable remains in the effluent of the sorbents column and can be analyzed with conventional methods after stabilization by addition of conc. HNO₃. As(V) is sorbed by the exchanger material. The As(V) concentration can be calculated as the difference between As_sol and As(III), neglecting very low contents of methylated species. Oxidation of Fe(II) by air followed by co-precipitation of arsenic with iron hydroxide was applied in field experiments to minimize the As concentration in seepage and mining water.     

Über die CH-Bestimmung in schwefelhaltigen Verbindungen

Zusammenfassung Verschiedene schwefelhaltige Verbindungen ergeben zu hohe Kohlenstoffwerte. Dieser Fehler kann behoben werden, indem die Einwaage im Verbrennungsschiffchen mit vorbehandeltem Cerdioxid abgedeckt oder vermischt wird.

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CH determination in containing compounds sulfur

Summary Various sulfur-containing compounds yield carbon values which are too high. This error can be eliminated by covering or mixing the aliquot in combustion boats with pretreated cerium dioxide.

     

De novo synthesis of 4'-ethoxy nucleoside analogues

Butenolides 5a and 13 were used as optically active templates in the de novo synthesis of 4'-disubstituted nucleoside analogues. The butenolides were reduced and acylated in situ to give acetates 10 and 14. Vorbrüggen coupling gave the protected nucleoside analogues 11 and 15. Reduction of 11 gave 4'-ethoxy-2',3'-dideoxythymidine (6) and deprotection of 15 gave 4'-ethoxy-2',3'-dideoxydidehydrothymidine (7). The cis-dihydroxylation of a variety of butenolides occurred with the major product formed from oxidation of the beta-face.     

Chemie der Pleuromutiline,IX. Konfigurationsumkehr der Methylgruppe am Kohlenstoff 6 im tricyclischen Gerüst des Diterpens Pleuromutilin

The contact of pleuromutilin derivatives with the protein moiety of cytochrome P-450 as well as its orientation towards the heme iron is mainly dependent on the steric environment of the hydrindanone-part of the tricyclus. The apparent affinity between substrate and enzyme, which is correlated with the rate of metabolism can be reduced by inversion of configuration at carbon 6. This inversion is achieved by equilibrating the diastereomeric ketones12 and13 followed by a selective reduction of the keto group at position 7. The 6-methylgroup of14 was assigned α-configuration on the basis of spectroscopic data in comparison to those of the naturally configurated compound14a.     

A new saponin lactone from Astragalus corniculatus

A new oleanane-type saponin lactone was isolated from the ethanolic extract of the aerial parts of Astragalus corniculatus Bieb. The structure of the saponin was elucidated as 19-hydroxyolean-12-ene-28, 21beta-olide 3beta-D-xylopyranoside (1) by chemical and spectral methods.     

Sensitivity improvement in laser ablation inductively coupled plasma mass spectrometry achieved using a methane/argon and methanol/water/argon mixed gas plasma

The influence of the addition of carbon using methane or methanol/water to an inductively coupled plasma (ICP) via the carrier gas flow on the sensitivity in laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was studied. During the ablation of SRM NIST 610 with simultaneous addition of CH(4) (0.6-1.4 ml min(-1)), a sensitivity enhancement of more than one order of magnitude for selected analytes (e.g. (75)As(+)) was observed. In addition to the sensitivity enhancement for As, Te, I and Se, also all other measured elements showed a significantly enhanced sensitivity (minimum by a factor of 2). Potential mechanisms for the observed intensity enhancement include charge transfer reactions, a change in the ICP shape and a temperature increase in the plasma. Furthermore, the aspiration of a methanol-water mixture into a cooled spray chamber and the simultaneous addition to the laser ablated aerosol was investigated. This type of mixing leads to a sensitivity enhancement up to a factor of 20. To prevent clogging of the sampler cone and skimmer cone by carbon deposition, a fast cleaning procedure for the interface is tested during running ICP, which allows the application of such a set-up for specific applications.