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.     

Evidence of distributed interstitialcy-like relaxation of the shear modulus due to structural relaxation of metallic glasses

The interstitialcy theory is used to calculate the kinetics of shear modulus relaxation induced by structural relaxation of metallic glasses. A continuous distribution of activation energies is shown to be a salient feature of the relaxation. High precision in situ contactless electromagnetic acoustic-transformation shear modulus (600- kHz) measurements performed on a Zr-based bulk metallic glass are found to strongly support the approach under consideration. It is revealed that the activation energy spectra derived from isothermal and isochronal shear modulus measurements are in good agreement with each other. It is concluded that the increase of the shear modulus during structural relaxation can be understood as a decrease of the concentration of structural defects similar to dumbbell interstitials in simple crystalline metals.     

Die quantitative chemische Bestimmung von Vitamin D

Zusammenfassung Die zur Vitamin D₂-Bestimmung bekannten spezifischen Farbreaktionen nachHalden und H.Brockmann werden durch die Unbeständigkeit des erhaltenen Farbtones und dieser durch Fettbegleitsubstanzen empfindlich gestört. Es gelingt, eine für Vitamin D spezifische, im Farbton beständige Reaktion bei Verwendung einer 20%igen Antimontrichloridund 5%igen Guajakol-Lösung in Chloroform. Die Empfindlichkeit der Reaktion ist 1200000. Es können quantitativ 15 in 2,8 ml Chloroform nachgewiesen werden bei tunlichster Einhaltung der beschriebenen Versuchsbedingungen.Der Einfluß der Sterine auf die Reaktion ist sehr gering, doch werden die Empfindlichkeit und die Spezifität dann vermindert, wenn sehr große Mengen dieser Begleitstoffe vorhanden sind. Mit Hilfe der Adsorption an frisch behandeltes, bei 120 erhitztes Aluminiumoxyd können störende Begleitstoffe abgetrennt werden. Das Vitamin D₂ wird dabei in einer scharf umrissenen Zone festgehalten, die im UV.-Licht weiß aufleuchtet.Die vorliegende Methode ist geeignet zur mengenmäßigen Bestimmung von Vitamin D in tierischen und pflanzlichen Fetten, in Milch und Milcherzeugnissen, in Kindernährmitteln, bestrahlten Hefen und pharmazeutischen Präparaten. Um die hier auftretenden, störenden Begleitstoffe auszuschalten, werden die Präparate nach der Extraktion des Vitamins D verseift, und der unverseifbare Anteil wird an Aluminiumoxyd adsorbiert. Dabei wird das Vitamin D bei Einhaltung der Arbeitsvorschrift immer in einer charakteristischen schmalen Zone festgehalten, die im Tageslicht gelb bis rosafarben erscheint. Durch die Anwesenheit von Vitamin A, Provitamin A und anderen. Carotinoiden kann die Reaktion gestört werden, so daß auch hier eine chromatographische Auftrennung erforderlich ist, die sich aber leicht durchführen läßt.     

Reaction of secondary and tertiary aliphatic halides with aromatic aldehydes mediated by chromium(II): a selective cross-coupling of alkyl and ketyl radicals

Takai-Utimoto reactions with secondary and tertiary aliphatic halides usually failed according to previous reports. Now, significant improvements could be achieved, and especially secondary aliphatic halides can be coupled to aromatic aldehydes in yields of up to >95%. A variety of processes are competing with the desired one, and thus conditions must be adapted to the nature of the aldehyde as well as the aliphatic halide used, as the outcome of these reactions is strongly affected by the putative radical intermediates.     

Sulfated glycopolymer thin films - preparation, characterization, and biological activity

The impact of heparinoid characteristics on model surfaces obtained from immobilization of sole sulfate groups as well as sulfated glycosides, sulfated cellulose, and definite heparin has been investigated. The obtained layers were physico-chemically characterized regarding film thickness, chemical composition, wettability, and surface morphology. Antithrombin adsorption, studied by fluorescence labeling, revealed a strong dependence on the presence of glycosidic structures and on the molecular weight of the grafted saccharide. On contact with whole blood, the coatings resulted in a diminished plasmatic and cellular coagulation in vitro, which did not reflect well the antithrombin binding. Therefore, more complex activating pathways are discussed.     

Analysis of sample of highly water-soluble Th-symmetric fullerenehexamalonic acid C66(COOH)12 by ion-chromatography and capillary electrophoresis

Ion chromatography (IC) was used to establish isomer purity of the highly water-soluble sample of fullerenehexamalonic acid, Th-symmetric hexakis-adduct C66(COOH)12. Sharp and symmetric peaks were obtained by IC using 1.0 M potassium hydroxide as eluent and applying gradient elution program. The identity of the two largest peaks in the chromatogram was assigned to Th-C66(COOH)12 and C66H(COOH)11. The developed IC procedure can be used for the semi-quantitative determination of the extent of the partial decarboxylation of the sample. As an alternative analytical technique, a CE procedure was introduced and its performance against IC was compared for this particular case.     

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.     

Catalyst volume to surface area constraints for nucleating carbon nanotubes

In this Article, we describe a carbon nanotube formation model in which sp2 carbon hemispheres form the embryonic caps from which a nanotube can grow. This requirement leads to a single wall carbon nanotube formation window concomitant with our systematic experimental findings, which show upper and lower diameter limits. Further, the successful formation of a nucleation cap (hemisphere) is governed by catalyst particle volume to surface area considerations. Single wall carbon nanotubes are only obtained when both the nanotube formation window and the precipitating catalyst size distribution cross over. The extent to which these two windows overlap establishes the mean diameter and diameter distribution of the obtained single wall carbon nanotubes.