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.     

Chaotic dynamics of a semiconductor laser with double cavity feedback: Applications to phase shift keying modulation

We report results on the numerical investigations of the dynamical behavior of a single mode semiconductor laser under the influence of double cavity optical feedback. We find that the system displays, under certain conditions, chaotic behaviors appropriate for chaos based communications. The synchronization of two unidirectional coupled (master-slave) systems is also studied. The influence of some parameters on the resynchronization and autocorrelation times is investigated. We find that the resynchronization time for the proposed scheme can be two orders of magnitude shorter when compared with that of the single-cavity feedback case. Very good conditions for message encoding by using the on/off phase shift keying encryption method are identified and examples of message encoding/decoding are presented.     

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.     

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.     

Seed Oil Fatty Acids of Mongolian Compositae: The trans‐Fatty Acids of Heteropappus hispidus,Asterothamnus centrali‐asiaticus and Artemisia palustris

Seed oils from the Compositae plant family are known to contain a variety of unusual fatty acids. Subsequent to the recent discovery of γ‐linolenic acid in Saussurea and Youngia, further Mongolian Compositae species were investigated for their seed oil fatty acid composition. A number of δ3trans‐fatty acids (16 : 1δ3t, 18 : 1δ3t and 18 : 3δ3t, 9c, 12c) were found in the seed oils of Heteropappus hispidus and Asterothamnus centrali‐asiaticus. The latter fatty acid, but not the trans‐monoenes, was also found in one species of Artemisia. These unusual fatty acid isomers were characterized by capillary gas‐liquid chromatographic (GLC) separations in combination with other chromatographic techniques (analytical thin layer chromatography, TLC and preparative argentation TLC), and infrared spectrocsopy (IR). Their identity was further confirmed by co‐chromatography with other seed oils known to contain these trans‐fatty acids. The fact that within the Compositae plant family there are apparently two or three distinct groups of genera containing δ3trans‐fatty acids is discussed.     

Synthesis of oxazoline functionalized polypropene using metallocene catalysts

Using two different zirconocene/MAO catalyst systems, propene was copolymerized with the comonomers 2‐(9‐decene‐1‐yl)‐1,3‐oxazoline and 2‐(4‐(10‐undecene‐1‐oxo)phenyl)‐1,3‐oxazoline, respectively. The catalysts used were rac‐Et[Ind]₂ZrCl₂ and rac‐Me₂Si[2‐Me‐4, 5‐BenzInd]₂ZrCl₂. Up to 0.53 mol‐% oxazoline could be incorporated into polypropene. Oxazoline content, molecular weight, degree of isotacticity and melting behavior were dependent on the catalyst system, comonomer structure and comonomer concentration in the feed.     

Synthesis and solution properties of rodlike polyelectrolytes

The synthesis and the solution behavior of rigid, rodlike cationic polyelectrolytes having (i) poly(p-phenylene) backbones and (ii) main chains composed of 4,4“-bis(2,2′:6′,2”-terpyridine)2′,5′-dihexyl-p-terphenyl moieties and ruthenium(II) centers are presented. All these polymers are shown to have a homogeneous constitution and degrees of polymerization of up to P_n ≈ 70. Their solution properties were analyzed using viscosimetry, small-angle X-ray scattering (SAXS) and osmometry. Pronounced polyelectrolyte effects were found in salt-free solutions using viscosimetry. Small-angle X-ray scattering demonstrated directly the strong correlation of the counterions and the macroions. The osmotic coefficients measured in salt-free solution as function of polyelectrolyte concentration were found to be lower than predicted by the cell model.