B Cell Epitopes of Four Fimbriae Antigens of Klebsiella pneumoniae: A Comprehensive In Silico Study for Vaccine Development

International Journal of Peptide Research and Therapeutics - Klebsiella pneumoniae is one of the major causes of nosocomial infections worldwide which can cause several diseases in children and...     

Isolation and characterization of a first set of polymorphic microsatellite markers in saffron, Crocus sativus (Iridaceae)

? Premise of the study: Twelve novel polymorphic microsatellite loci were developed and characterized from a repeat-enriched genomic library of Crocus sativus to study population and conservation genetics of this economically and medically important species. ? Methods and Results: The microsatellite loci were isolated using a modified Fast Isolation by AFLP of Sequences COntaining repeats (FIASCO) method. The average number of alleles per locus was 2.6. The observed and expected heterozygosities varied from 0.07 to 0.92 and 0.1 to 0.58, respectively. Polymorphic information content value ranged from 0.09 to 0.55 with an average of 0.34. Four out of twelve loci showed significant departures from Hardy-Weinberg equilibrium. ? Conclusions: The microsatellite markers reported here will be useful for evaluating genetic diversity and will likely serve as an ideal resource for use in marker-assisted breeding programs, germplasm analysis, and varietal identification.     

Why homocysteine-lowering therapy does not have beneficial effects on patients with cardiovascular disease?

Homocysteine is a sulfur-containing amino acid produced during the metabolism of methionine and elevated plasma levels of homocysteine have been linked to an increased risk of atherosclerosis and cardiovascular ischemic events by numerous authors. Several mechanisms by which elevated homocysteine impairs vascular function have been proposed including impairment of endothelial function and at least some of those mechanisms are induced via homocysteine-associated DNA hypomethylation. Oral administration of folic acid and B vitamins, required for remethylation of homocysteine to methionine, decreased plasma total homocysteine levels but clinical trials using folic acid and B vitamins did not confirm that the decreased plasma levels of homocysteine through diet or drugs may be paralleled by a reduction in cardiovascular risk. In our view a plausible explanation for the discordance between the epidemiologic studies and the results of the clinical trials may be related to the homocysteine-associated global DNA hypomethylation which cannot easily be reversed by homocysteine-lowering therapy.     

Di- and triorganotin(IV) carboxylates derived from triorganotin(IV) iodide with mixed organic groups on tin: Cyclic, hexameric triorganotin(IV) carboxylates

The reaction of ethyldiphenyltin(IV) iodide with silver benzoate in ethanol results in the formation of bis(benzoato)ethylphenyltin(IV), EtPhSn[OC(O)C₆H₅]₂ (1), by the cleavage of a phenyl group bound to tin. The reaction of ethyldiphenyltin(IV) iodide with silver acetate provides acetatoethyldiphenyltin(IV), EtPh₂SnOC(O)CH₃ (2). Similarly, the reaction of diphenylpropyltin(IV) iodide with silver acetate affords acetatodiphenyl-n-propyltin(IV), Ph₂PrSnOC(O)CH₃ (3). These three complexes were characterized by elemental analysis, mass spectrometry, and infrared spectroscopy (IR), as well as ¹H, ¹³C, and ¹¹⁹Sn NMR. The molecular structures of three complexes were also verified by single-crystal X-ray analyses. The X-ray structures show that 1 adopts a skew-trapezoidal bipyramidal structure, while 2 and 3 are rare, cyclic hexameric structures.     

Effect of sildenafil (Viagra) on memory retention of a passive avoidance response in rats

The effects of an intraperitoneal (i.p.) injection of different doses of sildenafil, a cyclic guanosin monophosphate (cGMP) specific phosphodiesterase type 5 (PDE 5) inhibitor, on memory retention of young (2-month-old) and middle aged (12-month-old) male Wistar rats were investigated. Passive avoidance behaviour was studied in a one trial learning, step--through type, passive avoidance task utilizing the natural preference of rats for a dark environment. In each category (young or middle-aged) different groups of rats received vehicle or sildenafil (1, 3, 10, 20 mg*kg(-1), i.p.) immediately after training and one group remained uninjected serwing as control. Retention latencies were measured 48 h later. To asses a possible non-specific proactive effect of sildenafil, the response latencies in a group of rats not receiving foot shock were also tested. The results showed that the post-training i.p. administration of sildenafil did not facilitate retention performance of a passive avoidance response in both young and middle aged rats compared to control or vehicle groups. Also, sildenafil did not affect response latencies in rats not having received the footshock on the training trial, indicating that sildenafil does not show a non-specific proactive affect on retention performance. The comparison of retention time between young and middle aged rats showed that the memory of the latter had been significantly reduced. In conclusion, this study suggests that sildenafil has no effects on memory retention in Wistar rats.     

Fine Root Production and Turnover in a Norway Spruce Stand in Northern Sweden: Effects of Nitrogen and Water Manipulation

Fine root length production, biomass production, and turnover in forest floor and mineral soil (0–30 cm) layers were studied in relation to irrigated (I) and irrigated-fertilized (IL) treatments in a Norway spruce stand in northern Sweden over a 2-year period. Fine roots (<1 mm) of both spruce and understory vegetation were studied. Minirhizotrons were used to estimate fine root length production and turnover, and soil cores were used to estimate standing biomass. Turnover was estimated as both the inverse of root longevity (RTL) and the ratio of annual root length production to observed root length (RTR). RTR values of spruce roots in the forest floor in I and IL plots were 0.6 and 0.5 y⁻¹, respectively, whereas the corresponding values for RTL were 0.8 and 0.9 y⁻¹. In mineral soil, corresponding values for I, IL, and control (C) plots were 1.2, 1.2, and 0.9 y⁻¹ (RTR) and 0.9, 1.1, and 1 y⁻¹ (RTL). RTR and RTL values of understory vegetation roots were 1 and 1.1 y⁻¹, respectively. Spruce root length production in both the forest floor and the mineral soil in I plots was higher than in IL plots. The IL-treated plots gave the highest estimates of spruce fine root biomass production in the forest floor, but, for the mineral soil, the estimates obtained for the I plots were the highest. The understory vegetation fine root production in the I and IL plots was similar for both the forest floor and the mineral soil and higher (for both layers) than in C plots. Nitrogen (N) turnover in the forest floor and mineral soil layers (summed) via spruce roots in IL, I, and C plots amounted to 2.4, 2.1, and 1.3 g N m⁻² y⁻¹, and the corresponding values for field vegetation roots were 0.6, 0.5, and 0.3 g N m⁻² y⁻¹. It was concluded that fertilization increases standing root biomass, root production, and N turnover of spruce roots in both the forest floor and mineral soil. Data on understory vegetation roots are required for estimating carbon budgets in model studies.     

Measuring Fine Root Turnover in Forest Ecosystems

Development of direct and indirect methods for measuring root turnover and the status of knowledge on fine root turnover in forest ecosystems are discussed. While soil and ingrowth cores give estimates of standing root biomass and relative growth, respectively, minirhizotrons provide estimates of median root longevity (turnover time) i.e., the time by which 50% of the roots are dead. Advanced minirhizotron and carbon tracer studies combined with demographic statistical methods and new models hold the promise of improving our fundamental understanding of the factors controlling root turnover. Using minirhizotron data, fine root turnover (y⁻¹) can be estimated in two ways: as the ratio of annual root length production to average live root length observed and as the inverse of median root longevity. Fine root production and mortality can be estimated by combining data from minirhizotrons and soil cores, provided that these data are based on roots of the same diameter class (e.g., < 1 mm in diameter) and changes in the same time steps. Fluxes of carbon and nutrients via fine root mortality can then be estimated by multiplying the amount of carbon and nutrients in fine root biomass by fine root turnover. It is suggested that the minirhizotron method is suitable for estimating median fine root longevity. In comparison to the minirhizotron method, the radio carbon technique favor larger fine roots that are less dynamics. We need to reconcile and improve both methods to develop a more complete understanding of root turnover.     

Null genotype of glutathione S-transferase M1 is associated with senile cataract susceptibility in non-smoker females

In the present study, we investigated whether the polymorphisms of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes are risk factors of cataract among Iranian population in a molecular epidemiological way. Blood samples from 150 subjects with cataract (72 male; 78 female) and 150 age- and sex-matched healthy persons were collected. Both patient and control groups were unrelated Iranian Muslims. Using PCR-based method, the genotypes were determined. The null GSTM1 genotype was associated with a 2.38-fold increase in the risk of developing cataract (OR=2.38; 95% CI=1.46-3.89; P = 0.0003). After stratification by sex of subjects, the association was apparent only among women (OR=3.20; 95% CI=1.58-6.52; P = 0.0007). The GSTT1 null genotype was associated with a 1.10-fold increased risk of developing cataract, but this association was not statistically significant. After stratification by sex of subjects, same results were obtained. Female patients with null genotype for GSTM1 and no history of smoking had a 3.45-fold increased cataract risk (P < 0.05), whereas females who were null for GSTM1 and having history of smoking were not at increased risk of cataract.     

A complete dielectric response model for liquid water: a solution of the Bethe ridge problem

We present a complete yet computationally simple model for the dielectric response function of liquid water over the energy-momentum plane, which, in contrast to earlier models, is consistent with the recent inelastic X-ray scattering spectroscopy data at both zero and finite momentum transfer values. The model follows Ritchie's extended-Drude algorithm and is particularly effective at the region of the Bethe ridge, substantially improving previous models. The present development allows for a more accurate simulation of the inelastic scattering and energy deposition process of low-energy electrons in liquid water and other biomaterials. As an example, we calculate the stopping power of liquid water for electrons over the 0.1-10 keV range where direct experimental measurements are still impractical and the Bethe stopping formula is inaccurate. The new stopping power values are up to 30-40% lower than previous calculations. Within the range of validity of the first Born approximation, the new values are accurate to within the experimental uncertainties (a few percent). At the low end, the introduction of Born corrections raises the uncertainty to perhaps approximately 10%. Thus the present model helps extend the ICRU electron stopping power database for liquid water down to about two orders of magnitude with a comparable level of uncertainty.     

Corrosion risk associated with microbial souring control using nitrate or nitrite

Souring, the production of hydrogen sulfide by sulfate-reducing bacteria (SRB) in oil reservoirs, can be controlled through nitrate or nitrite addition. To assess the effects of this containment approach on corrosion, metal coupons were installed in up-flow packed-bed bioreactors fed with medium containing 8 mM sulfate and 25 mM lactate. Following inoculation with produced water to establish biogenic H₂S production, some bioreactors were treated with 17.5 mM nitrate or up to 20 mM nitrite, eliminating souring. Corrosion rates were highest near the outlet of untreated bioreactors (up to 0.4 mm year^–1). Nitrate (17.5 mM) eliminated sulfide but gave pitting corrosion near the inlet of the bioreactor, whereas a high nitrite dose (20 mM) completely eliminated microbial activity and associated corrosion. More gradual, step-wise addition of nitrite up to 20 mM resulted in the retention of microbial activity and localized pitting corrosion, especially near the bioreactor inlet. We conclude that: (1) SRB control by nitrate or nitrite reduction shifts the corrosion risk from the bioreactor outlet to the inlet (i.e. from production to injection wells) and (2) souring treatment by continuous addition of a high inhibitory nitrite dose is preferable from a corrosion-prevention point of view.