Kinetics for hybridization of peptide nucleic acids (PNA) with DNA and RNA studied with the BIAcore technique

The binding of a mixed-sequence pentadecamer PNA (peptide nucleic acid) containing all four nucleobases to the fully complementary as well as various singly mismatched RNA and DNA oligonucleotides has been systematically investigated using thermal denaturation and BIAcore surface-interaction techniques. The rate constants for association (k(a)) and dissociation (k(d)) of the duplex formation as well as the thermal stability (melting temperature, T(m)) of the duplexes have been determined. Upon binding to PNA tethered via a biotin-linker to streptavidin at the dextran/gold surface, DNA and RNA sequences containing single mismatches at various positions in the center resulted in increased dissociation and decreased association rate constants. T(m) values for PNA x RNA duplexes are on average 4 degrees C higher than for PNA x DNA duplexes and follow quantitatively the same variation with mismatches as do the PNA x DNA duplexes. Also a faster k(a) and a slower k(d) are found for PNA x RNA duplexes compared to the PNA x DNA duplexes. An overall fair correlation between T(m), k(a), and k(d) is found for a series of PNA x DNA and PNA x RNA duplexes although the determination of k(a) seemed to be prone to artifacts of the method and was not considered capable of providing absolute values representing the association rate constant in bulk solution.     

Crystal chemistry of α-(Zn,M)2V2O7 solid solutions correlation between preference for five-coordination and extension of solid solubility

Solid solutions of $\text{M}$₂V₂O₇ in α-Zn₂V₂O₇ have been prepared and equilibrated at 600°C ($\text{M}\text{=}\text{Mg, Ca, Mn, Co, Ni, Cu, Zn, and Cd}$). The crystal structure of α-Zn₂V₂O₇ contains only one type of metal site, which is five-coordinated by a somewhat distorted trigonal bipyramid ZnO₅ (Gopal & Calvo, 1973). The solubility range is largest for Cu²⁺ and Co²⁺ which can substitute for about 35% of the zinc atoms. The cations can be arranged in the following sequence with respect to their solubility in α-Zn₂V₂O₇, which accords well with these ions' preference for five-coordination:

$\text{Zn}{}^{\mathrm{2+}}\text{>> (Cu}{}^{\mathrm{2+}}\text{,Co}{}^{\mathrm{2+}}\text{) > Mg}{}^{\mathrm{2+}}\text{>(Ni}{}^{\mathrm{2+}}\text{, Mn}{}^{\mathrm{2+}}\text{) > Cd}{}^{\mathrm{2+}}$

     

Effects of highly purified eicosapentaenoic acid and docosahexaenoic acid on fatty acid absorption, incorporation into serum phospholipids and postprandial triglyceridemia

Fourteen healthy volunteers were randomly allocated to receive 4 g highly purified ethyl esters of eicosapentaenoic acid (EPA) (95% pure, n=7) or docosahexaenoic acid (DHA) (90% pure, n=7) daily for 5 wk in supplement to their ordinary diet. The n−3 fatty acids were given with a standard high-fat meal at the beginning and the end of the supplementation period. EPA and DHA induced a similar incorporation into chylomicrons which peaked 6 h after the meal. The relative uptake of EPA and DHA from the meal was >90% compared with the uptake of oleic acid. During absorption, there was no significant elongation or retroconversion of EPA or DHA in total chylomicron fatty acids. The concentration of EPA decreased by 13% and DHA by 62% (P<0.001) between 6 and 8 h after the meal. During the 5-wk supplementation period, EPA showed a more rapid and comprehensive increase in serum phospholipids than did DHA. DHA was retroconverted to EPA, whereas EPA was elongated to docosapentaenoic acid (DPA). The postprandial triglyceridemia was suppressed by 19 and 49% after prolonged intake of EPA and DHA, respectively, indicating that prolonged intake of DHA is equivalent to or even more efficient than that of EPA in lowering postprandial triglyceridemia. This study indicates that there are metabolic differences between EPA and DHA which may have implications for the use of n−3 fatty acids in preventive and clinical medicine.     

宽带接入运营商业务赢利的新机遇

固定和移动宽带用户的增长及其对新业务便利性的需求带来了一系列新的机遇.许多运营商对互联网"黑洞"的惧怕使他们将未来的赌注押在了更高价值的服务与内容上,他们希望时间停留在美好的旧时光,仍然能够游刃有余地控制整条价值链,但最终不可逃避的是,宽带必须依靠自身的特点成为一门好的生意.     

Effect of supplement with lactic-acid producing bacteria on fatigue and physical activity in patients with chronic fatigue syndrome

Disturbances in intestinal microbial ecology and in the immune system of the host have been implicated as a part of the pathogenesis in chronic fatigue syndrome. Probiotic lactic acid producing bacteria have been shown to prevent and alleviate gastrointestinal disturbances and to normalize the cytokine profile which might be of an advantage for patients suffering from chronic fatigue syndrome. The aim of the study was to evaluate the effect of Lactobacillus paracasei ssp. paracasei F19, Lactobacillus acidophilus NCFB 1748 and Bifidobacterium lactis Bb12 on fatigue and physical activity in CFS patients. Fifteen patients fulfilling the criteria set by international researchers in the field at the US Centre for Disease Control and Prevention in 1994 for chronic fatigue syndrome, were included in the study. The patients had high fatigue severity scores and high disability scores. During the first two weeks baseline observations without treatment were assessed, succeeded by four weeks of intake of a probiotic product and a four-week follow-up period. The fatigue, health and physical activity was assessed by the use of the Visual Analogue Scales and the SF-12 Health Survey. Faecal samples were collected and the normal microflora was analysed. Neurocognitive functions improved during the study period while there were no significant changes in fatigue and physical activity scores. No major changes occurred in the gastrointestinal microflora. At the end of the study 6 of 15 patients reported that they had improved according to the assessment described. The findings in this study that improvement of health is possible to achieve should encourage further studies with interventions with probiotics in patients with CFS.     

Reducing the emission of particles from a diesel engine by adding an oxygenate to the fuel

Particulate and high emissions of NO(x) are the main problems that are associated with diesel engines. Therefore, techniques and fuels that promote a reduction in these emissions currently are attracting great interest. In this paper, a mixture of acetal and regular diesel fuel has been tested in a heavy-duty diesel engine. The effect was a marked decrease in particle number and the estimated particle mass. A small reduction of the engine power was also observed; however, the net effect was nevertheless a reduction in the emission of CO2 per European stationary cycle. The emissions of HC, CO, NO(x), some aldehydes, and hydrocarbons were only slightly affected by the new fuel composition. An exception was the emission of acetaldehyde, which was almost quadrupled, probably reflecting the decomposition and oxidation of acetal to acetaldehyde.     

Experiential household food insecurity in an urban underserved slum of North India

One-third of India’s urban population resides in extreme poverty, in slums and squatters. Food insecurity remains a visible reality among this segment. Yet, it is scarcely documented. This paper describes levels and determinants of experiential household food insecurity (HFI) in an underserved urban slum of Delhi (India) and reports the internal validity and reliability of the measure used to assess experiential HFI. A four-item scale was adapted from the U.S. six-item short-form food security scale and was administered in Hindi through household interviews with 410 female adults. Association of HFI with household economic and socio-demographic characteristics were examined using multiple logistic regression. Cronbach’s alpha and Rasch-model-based item fit statistics were used to assess reliability and internal validity. Fifty-one percent of households were food insecure. Significant HFI predictors were unemployed to employed family members’ ratio of > 3:1 (Odds Ratio 2.1, Confidence Interval 1.2 – 3.4) and low household standard of living (OR 4.9, C.I. 2.7 – 8.9). Cronbach’s alpha was 0.8. Item severities as estimated under Rasch model assumptions spanned 9.7 logits. Item infit statistics (0.77 – 1.07) indicated that the Rasch model fit the data well. Item outfit statistics suggested that one item was inconsistently understood by a small proportion of respondents. For improving HFI among the urban poor, in addition to improving behaviors/entitlement access, programs should consider linkage of urban poor to existing employment schemes, upgrading of their skills and linkage to potential employers. The adapted scale was reliable and easy to administer. However, being a subjective assessment, its sensitivity to social expectation and its association with nutrition security require examination.