Trading genes along the silk road: mtDNA sequences and the origin of central Asian populations

Central Asia is a vast region at the crossroads of different habitats, cultures, and trade routes. Little is known about the genetics and the history of the population of this region. We present the analysis of mtDNA control-region sequences in samples of the Kazakh, the Uighurs, the lowland Kirghiz, and the highland Kirghiz, which we have used to address both the population history of the region and the possible selective pressures that high altitude has on mtDNA genes. Central Asian mtDNA sequences present features intermediate between European and eastern Asian sequences, in several parameters-such as the frequencies of certain nucleotides, the levels of nucleotide diversity, mean pairwise differences, and genetic distances. Several hypotheses could explain the intermediate position of central Asia between Europe and eastern Asia, but the most plausible would involve extensive levels of admixture between Europeans and eastern Asians in central Asia, possibly enhanced during the Silk Road trade and clearly after the eastern and western Eurasian human groups had diverged. Lowland and highland Kirghiz mtDNA sequences are very similar, and the analysis of molecular variance has revealed that the fraction of mitochondrial genetic variance due to altitude is not significantly different from zero. Thus, it seems unlikely that altitude has exerted a major selective pressure on mitochondrial genes in central Asian populations.     

Influence of water activity on microbial development in minced,cured pork,in relation to gas headspace composition

The water activity (a_w) of a cured minced meat mixture was reduced with NaCl or glycerol + NaCl and the products stored in air, N₂ or CO₂ at 4°C. The lower the a_w, the lower was the growth rate of the total microflora except when a_w was reduced below 0·98 with glycerol and products were stored in CO₂, when the growth rate was independent of a_w. At a_w 0·94 NaCl was more effective than glycerol + NaCl in reducing the growth rate. In air the final microflora of products stored at a_w ≤0·96 consisted primarily of yeasts while at 0.98 a_w, both Lactobacillus (62%) and yeasts (38%) were found. In CO₂ and N₂Lactobacillus predominated at 0·94–0·98 a_w when 2% NaCl or NaCl + glycerol were used. At 0·94 a_w, produced using 6% NaCl, a heterogenous final microflora was found, including Micrococcus and Staphylococcus. An increase in the microbial shelf-life of meat products may be obtained by reducing the a_w, particularly for use with storage in N₂- and CO₂-atmospheres. The type of solute chosen to regulate a_w may affect the solubility of CO₂, which in turn affects the shelf-life.     

Anemia increases gastric blood flow in noncirrhotic and cirrhotic patients

BACKGROUND: Previous studies in rats have demonstrated that anemia induces a significant increment in gastric mucosal blood flow. In the present study, we investigated whether chronic anemia induces similar changes in gastric blood perfusion in humans, and if this effect is also present in cirrhotic patients in whom gastric blood flow is usually increased in basal conditions. METHODS: Gastric mucosal blood perfusion was assessed by means of laser-Doppler flowmetry and reflectance spectrophotometry applied through the endoscope. RESULTS: Anemia significantly increases laser-Doppler signal in cirrhotic (2.3 +/- 0.11 vs 2.9 +/- 0.22 volts, p < 0.05) and noncirrhotic patients (1.71 +/- 0.15 vs 2.24 +/- 0.17, p < 0.05). In anemic patients the index of hemoglobin concentration of the gastric mucosa, assessed by reflectance spectrophotometry, was significantly decreased in cirrhotic patients (107.6 +/- 4.7 vs 95.5 +/- 3.3, p < 0.05) and noncirrhotic patients (93.9 +/- 4.1 vs 76.1 +/- 4.2, p < 0.01), whereas the index of oxygen saturation was increased (36.7 +/- 0.7 vs 40.4 +/- 1.4, p = 0.05; and 36.4 +/- 1.1 vs 43.2 +/- 1.9, p < 0.01, respectively). CONCLUSIONS: In conclusion, chronic anemia is associated with an enhanced gastric blood perfusion reflected by an increased laser-doppler signal and gastric mucosal oxygen index despite a decrease in gastric hemoglobin concentration. In cirrhotic patients, anemia promotes a further increment in its basal gastric hyperemia.     

Phase studies of a liquid crystalline polymer: hydroxypropyl cellulose

Phase diagrams for the isotropic-anisotropic phase transition in solutions of a thermotropic cellulose derivative, hydroxypropyl cellulose are presented. The effect of the molecular weight is demonstrated. A comparison to the theory of semi-rigid liquid crystalline polymers is given.     

High flux hemofiltration

Experiments were performed using a new hollow fiber hemofilter. Ultrafiltration rates and whole blood urea clearances were measured in post-dilution hemofiltration. High ultrafiltration rates were obtained with the new hemofilter. No adverse effects were detected despite filtration fractions above 45%. These experiments suggest that it is possible in post-dilution hemofiltration to obtain small solute clearances comparable to those of hemodialysis without apparent deleterious effects.     

Bleaching of vegetable oils: I. Conversions in soybean oil,triolein and trilinolein

Soybean oil, triolein and trilinolein were treated with acid-activated earth (2–15%) at 25–120 C. With low initial peroxides and in the absence of air, little additional conjugation was found. With high initial peroxides or in the presence of air, conjugated dienes and trienes were formed particularly with high amounts of earth. At higher temperatures and longer bleaching times the amount of conjugated compounds also increased. It can be concluded from the bleaching experiments with triolein and trilinolein that conjugated dienes, trienes and tetraenes are formed much more easily with linoleate than with oleate.     

Stickstoffbindung in Soda- und Hochofenschlacken

Stand der Erkenntnisse über die Entstickung von Roheisen durch Soda und die Stickstoffbindung in Schlacke. Analytisch-chemischer Versuchsplan. Untersuchung von Betriebsschlacken und entsprechenden synthetischen Schmelzen sowie Aufstellung einer Stickstoffbilanz der Sodabehandlung von Thomasroheisen. Deutung der Entstickung bei der Sodabehandlung. Hinweise auf die Stickstoffbewegung im Hochofen.     

Characterisation of electrodeposited nanocrystalline Ni–Mo alloys

Ni–Mo nanocrystalline layers were electrodeposited using direct current from citrate–ammonia solutions. The quartz crystal microbalance investigation confirms that the discharge process starts with hydrogen evolution before the onset of the alloy deposition. The grain size was estimated from X-ray line broadening. It decreases when the molybdenum content is increased. It is smaller for layers deposited at pH 9.5 than 8.5. The microhardness exhibits a maximum close to 800 Vickers for _Mo around 17 wt%. For higher _Mo a softening is observed showing a deviation from Hall-Petch behaviour due to small grain size. In deaerated hydrochloric solutions, the layers show a large passivation domain without any pitting. The corrosion currents as well as the passivation currents, higher than for the bulk Hastelloy B alloy, decrease when _Mo is increased.     

A microfluidic platform using molecular beacon-based temperature calibration for thermal dehybridization of surface-bound DNA

This work presents a simple microfluidic device with an integrated thin-film heater for studies of DNA hybridization kinetics and double-stranded DNA melting temperature measurements. The heating characteristics of the device were evaluated with a novel, noninvasive indirect technique using molecular beacons as temperature probes inside reaction chambers. This is the first microfluidic device in which thermal dehybridization of surface-bound oligonucleotides was performed for measurement of double-stranded DNA melting temperatures with +/- 1 degrees C precision. Surface modification and oligonucleotide immobilization were performed by continuously flowing reagents through the microchannels. The resulting reproducibility of oligonucleotide surface densities, at 9% RSD, was better than for the same modification chemistries on glass slides in unstirred reagent solutions (RSD=20%). Moreover, the surface density of immobilized DNA probe molecules could be varied controllably by changing the concentration of the reagent solution used for immobilization. Thus, excellent control of surface characteristics was made possible, something which is often difficult to achieve with larger devices. Solid-phase hybridization reactions, a fundamental aspect of microarray technologies often taking several hours in conventional systems, were reduced to minutes in this device. It was also possible to determine forward rate constants for hybridization, k. These varied from 820,000 to 72,000 M(-1) s(-1), decreasing as surface densities increased. Surface densities could therefore be optimized to obtain rapid hybridization using such an approach. Taken together, this combined microfluidic/small-volume heating approach represents a powerful tool for surface-based DNA analysis.