Selective recovery of precious metals by persimmon waste chemically modified with dimethylamine

Persimmon waste was chemically modified with dimethylamine (DMA) to obtain a tertiary-amine-type gel, named DMA persimmon waste gel (DMA-PW). It was found to be effective for the adsorption of Au(III), Pd(II), and Pt(IV) in hydrochloric acid medium. In contrast, base metals such as Cu(II), Zn(II), Fe(III), and Ni(II) were not practically adsorbed. The formation of ion pairs of the metal chloro complex anions with the protonated adsorption gels was proposed as the main adsorption process. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 5.63 mol/kg dry gel and comparable capacities, i.e., 0.42 and 0.28 mol/kg for Pd(II) and Pt(IV), respectively. According to the kinetic and electrochemical studies, the adsorption rate of Au(III) was greatly enhanced by the chemical modification. Also, its excellent adsorption characteristics for the precious metals were confirmed by adsorption and elution tests using a column packed with the DMA-PW gel.     

Acetoxy drug: protein transacetylase catalyzed activation of human platelet nitric oxide synthase by polyphenolic peracetates

An enhanced intracellular level of Nitric oxide (NO) is essential to ameliorate several pathological conditions of heart and vasculature necessitating the activation of NOS. We have projected in this report the acetylation of eNOS by polyphenolic peracetates (PA) catalyzed by the novel enzyme acetoxy drug: protein transacetylase (TAase) discovered in our laboratory as an unambiguous way of activating NOS which results in the manifestation of physiological action. The human platelet was chosen as the experimental system in order to validate the aforementioned proposition. PA caused profound irreversible activation of platelet NADPH cytochrome c reductase mediated by TAase. The convincing biochemical evidences are presented to show that PA could cause acetylation of the reductase domain of NOS leading to the activation of eNOS in tune with their specificities to platelet TAase. As a result, the enhanced level of NO due to activation of platelet eNOS by PA was found to inhibit the ADP-induced platelet aggregation. The present studies highlight for the first time the role of PA as the novel potent agent for enhancing the intracellular NO levels.     

Effects of temperature on competition and relative dominance of <Emphasis Type="Italic">Bradyrhizobium japonicum</Emphasis> and <Emphasis Type="Italic">Bradyrhizobium elkanii</Emphasis> in the process of soybean nodulation

Background and aims

Bradyrhizobium japonicum and Bradyrhizobium elkanii dominated soybean nodules in temperate and subtropical regions in Nepal, respectively, in our previous study. The aims of this study were to reveal the effects of temperature on the nodulation dominancy of B. japonicum and B. elkanii and to clarify the relationship between the effects of temperature and the climate-dependent distribution of Bradyrhizobium species.

Methods

A laboratory competition experiment was conducted between B. japonicum and B. elkanii strains isolated from the same temperate location in Nepal. A mixture of each strain was inoculated into sterilized vermiculite with or without soybean seeds, and inoculated samples were incubated at 33/27 (day/night) and 23/17 °C. Relative populations in the non-rhizosphere, rhizosphere, and nodules were determined by competitive PCR using specific primers for each strain at 0, 1, 2, and 4 weeks after inoculation.

Results

Both separately inoculated B. japonicum and B. elkanii strains formed nodules at both temperatures. Under competitive conditions, B. japonicum strains dominated at low temperature; however, at high temperature, both strains achieved co-nodulation in 1 week, with B. elkanii dominating after 2 weeks. The relative populations of both strains were similar in the non-rhizosphere and rhizosphere at low temperature, but B. elkanii strains dominated in these regions at high temperature.

Conclusions

The domination of B. japonicum strains in nodules at the low temperature appeared to be due to preferential infection, while the domination of B. elkanii strains at high temperature appeared to be due to the higher population of B. elkanii in the non-rhizosphere and rhizosphere, in addition to its domination in nodules after co-nodulation. The effects of temperature on the competition between B. japonicum and B. elkanii strains were remarkable and corresponded with the distribution of bradyrhizobial species in Nepal.

     

Identification of novel genomic regions associated with resistance to <Emphasis Type="Italic">Pyrenophora tritici</Emphasis>-<Emphasis Type="Italic">repentis</Emphasis> races 1 and 5 in spring wheat landraces using association analysis

Tan spot, caused by Pyrenophora tritici-repentis, is a major foliar disease of wheat worldwide. Host plant resistance is the best strategy to manage this disease. Traditionally, bi-parental mapping populations have been used to identify and map quantitative trait loci (QTL) affecting tan spot resistance in wheat. The association mapping (AM) could be an alternative approach to identify QTL based on linkage disequilibrium (LD) within a diverse germplasm set. In this study, we assessed resistance to P. tritici-repentis races 1 and 5 in 567 spring wheat landraces from the USDA-ARS National Small Grains Collection (NSGC). Using 832 diversity array technology (DArT) markers, QTL for resistance to P. tritici-repentis races 1 and 5 were identified. A linear model with principal components suggests that at least seven and three DArT markers were significantly associated with resistance to P. tritici-repentis races 1 and 5, respectively. The DArT markers associated with resistance to race 1 were detected on chromosomes 1D, 2A, 2B, 2D, 4A, 5B, and 7D and explained 1.3–3.1% of the phenotypic variance, while markers associated with resistance to race 5 were distributed on 2D, 6A and 7D, and explained 2.2–5.9% of the phenotypic variance. Some of the genomic regions identified in this study correspond to previously identified loci responsible for resistance to P. tritici-repentis, offering validation for our AM approach. Other regions identified were novel and could possess genes useful for resistance breeding. Some DArT markers associated with resistance to race 1 also were localized in the same regions of wheat chromosomes where QTL for resistance to yellow rust, leaf rust and powdery mildew, have been mapped previously. This study demonstrates that AM can be a useful approach to identify and map novel genomic regions involved in resistance to P. tritici-repentis.     

Free radical reactions of a naturally occurring flavone baicalein and possible mechanisms towards its membrane protective properties

Baicalein (5, 6, 7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one), a naturally occurring flavone present in some of the medicinal plants is known for its potential therapeutic effects, such as cardioprotective, anticancer and anti-inflammatory properties. However, detailed role and mechanisms behind its protective properties against different generators for oxidative stress have not been examined. In the present study, we investigated the possible protective ability of baicalein against the membrane damage caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS) and the mechanisms involved using pulse radiolysis technique. Baicalein offered efficient protection even at a concentration of 10 microM towards membrane damage caused by lipid peroxidation induced by the gamma-radiation, peroxyl radicals, ascorbate-Fe2+ and peroxynitrite in rat liver mitochondria and heart homogenate. To elucidate its reaction mechanisms with biologically relevant radicals, transient absorption spectroscopy employing pulse radiolysis technique was used. Baicalein showed fairly high rate constants (3.7 x 10(9), 1.3 x 10(9) and 8.0 x 10(8) dm3 mol(-1) s(-1) for hydroxyl, azidyl and alkylchloroperoxyl radicals, respectively), suggesting that baicalein can act as an effective scavenger of these radicals. In each case, the phenoxyl radical of baicalein was generated. Thus, it was evident that the phenolic moiety of baicalein was responsible for the free radical scavenging process. Baicalein also reacts with linoleic acid peroxyl radical (LOO*), indicating its ability to act as a chain breaking antioxidant. Peroxynitrite-mediated radicals were shown to be reactive towards baicalein and the bimolecular rate constants were 2.5 x 10(7) and 3 x 10(8) dm3 mol(-1) s(-1) for *NO2 and CO3*(-) radicals, respectively. In conclusion, our results revealed the potential of baicalein in protecting mitochondrial membrane against oxidative damage induced by the four different agents. We propose that the protective effect is mediated via scavenging of primary and secondary radicals generated during oxidative stress.     

Ultrasensitive immuno-detection using viral nanoparticles with modular assembly using genetically-directed biotinylation

We report a novel, modular approach to immuno-detection based on antibody recognition and PCR read-out that employs antibody-conjugated bacteriophage and easily-manipulated non-pathogenic viruses as affinity agents. Our platform employs phage genetically tagged for in vivo biotinylation during phage maturation that can easily be linked, through avidin, to any biotinylated affinity agent, including full-length antibodies, peptides, lectins or aptamers. The presence of analyte is reported with high sensitivity through real-time PCR. This approach avoids the need to clone antibody-encoding DNA fragments, allows the use of full-length, high affinity antibodies and, by having DNA reporters naturally encapsulated inside the bacteriophage, greatly reduces nonspecific binding of DNA. We validate the efficacy of this new approach through the detection of Vascular Endothelial Growth Factor, a known angiogenic cancer biomarker protein, at attomolar concentrations in bronchoalveolar lavage fluid.     

Redox regulation of apurinic/apyrimidinic endonuclease 1 activity in Long-Evans Cinnamon rats during spontaneous hepatitis

The Long-Evans Cinnamon (LEC) rat is an animal model for Wilson’s disease. This animal is genetically predisposed to copper accumulation in the liver, increased oxidative stress, accumulation of DNA damage, and the spontaneous development of hepatocellular carcinoma. Thus, this animal model is useful for studying the relationship of endogenous DNA damage to spontaneous carcinogenesis. In this study, we have investigated the apurinic/apyrimidinic endonuclease 1 (APE1)-mediated excision repair of endogenous DNA damage, apurinic/apyrimidinic (AP)-sites, which is highly mutagenic and implicated in human cancer. We found that the activity was reduced in the liver extracts from the acute hepatitis period of LEC rats as compared with extracts from the age-matched Long-Evans Agouti rats. The acute hepatitis period had also a heightened oxidative stress condition as assessed by an increase in oxidized glutathione level and loss of enzyme activity of glyceraldehyde 3-phosphate dehydrogenase, a key redox-sensitive protein in cells. Interestingly, the activity reduction was not due to changes in protein expression but apparently by reversible protein oxidation as the addition of reducing agents to extracts of the liver from acute hepatitis period reactivated APE1 activity and thus, confirmed the oxidation-mediated loss of APE1 activity under increased oxidative stress. These findings show for the first time in an animal model that the repair mechanism of AP-sites is impaired by increased oxidative stress in acute hepatitis via redox regulation which contributed to the increased accumulation of mutagenic AP-sites in liver DNA.     

Slow repair of lipid peroxidation-induced DNA damage at p53 mutation hotspots in human cells caused by low turnover of a DNA glycosylase

Repair of oxidative stress- and inflammation-induced DNA lesions by the base excision repair (BER) pathway prevents mutation, a form of genomic instability which is often observed in cancer as ‘mutation hotspots’. This suggests that some sequences have inherent mutability, possibly due to sequence-related differences in repair. This study has explored intrinsic mutability as a consequence of sequence-specific repair of lipid peroxidation-induced DNA adduct, 1, N⁶-ethenoadenine (εA). For the first time, we observed significant delay in repair of ϵA at mutation hotspots in the tumor suppressor gene p53 compared to non-hotspots in live human hepatocytes and endothelial cells using an in-cell real time PCR-based method. In-cell and in vitro mechanism studies revealed that this delay in repair was due to inefficient turnover of N-methylpurine-DNA glycosylase (MPG), which initiates BER of εA. We determined that the product dissociation rate of MPG at the hotspot codons was ≈5–12-fold lower than the non-hotspots, suggesting a previously unknown mechanism for slower repair at mutation hotspots and implicating sequence-related variability of DNA repair efficiency to be responsible for mutation hotspot signatures.     

Factors associated with early initiation of breastfeeding among Nepalese mothers: further analysis of Nepal Demographic and Health Survey, 2011

Background

Timely initiation of breastfeeding has been reported to reduce neonatal mortality by 19.1%. The World Health Organisation recommends early initiation of breastfeeding i.e. breastfeeding a newborn within the first hour of life. Knowledge on the rate and the determinants of early initiation of breastfeeding may help health program managers to design and implement effective breastfeeding promotion programs. The aim of this study was to determine the rate and the determinants of early initiation of breastfeeding in Nepal.

Methods

This study used the data from Nepal Demographic and Health Survey (NDHS) 2011 which is a nationally representative sample study. Chi square test and multiple logistic regression analysis were used to examine the factors associated with early initiation of breastfeeding (within one hour of birth).

Results

Of 4079 mothers, 66.4% initiated breastfeeding within one hour of delivery. Mothers with higher education (Odds Ratio (OR) 2.56; 95% CI : 1.26, 5.21), mothers of disadvantaged Janjati ethnicity (OR 1.43; 95% CI : 1.04, 1.94), mothers who were involved in agriculture occupation (OR 1.51; 95% CI : 1.16, 1.97), mothers who delivered in a health facility (OR 1.67; 95% CI : 1.25, 2.23), whose children were large at birth (OR 1.46; 95% CI : 1.07, 1.99) were more likely to initiate breastfeeding within the first hour of child birth.

Conclusions

Results suggest that two thirds of children in Nepal were breastfed within the first hour after birth. Although there was a higher prevalence of early initiation of breastfeeding among mothers who delivered in health facilities compared to mothers who delivered at home, universal practice of early initiation of breastfeeding should be a routine practice. The findings suggest the need of breastfeeding promotion programs among the mothers who are less educated, and not working. Such breastfeeding promotion programmes could be implemented via Nepal’s extensive network of community-based workers.

     

Enhanced Antitumor Immunity Contributes to the Radio-Sensitization of Ehrlich Ascites Tumor by the Glycolytic Inhibitor 2-Deoxy-D-Glucose in Mice

Two-deoxy-D-glucose (2-DG), an inhibitor of glycolysis differentially enhances the radiation and chemotherapeutic drug induced cell death in cancer cells in vitro, while the local tumor control (tumor regression) following systemic administration of 2-DG and focal irradiation of the tumor results in both complete (cure) and partial response in a fraction of the tumor bearing mice. In the present studies, we investigated the effects of systemically administered 2-DG and focal irradiation of the tumor on the immune system in Ehrlich ascites tumor (EAT) bearing Strain “A” mice. Markers of different immune cells were analyzed by immune-flow cytometry and secretary cytokines by ELISA, besides monitoring tumor growth. Increase in the expression of innate (NK and monocytes) and adaptive CD4⁺cells, and a decrease in B cells (CD19) have been observed after the combined treatment, suggestive of activation of anti-tumor immune response. Interestingly, immature dendritic cells were found to be down regulated, while their functional markers CD86 and MHC II were up regulated in the remaining dendritic cells following the combination treatment. Similarly, decrease in the CD4⁺ naïve cells with concomitant increase in activated CD4⁺ cells corroborated the immune activation. Further, a shift from Th2 and Th17 to Th1 besides a decrease in inflammatory cytokines was also observed in the animals showing complete response (cure; tumor free survival). This shift was also complimented by respective antibody class switching followed by the combined treatment. The immune activation or alteration in the homeostasis favoring antitumor immune response may be due to depletion in T regulatory cells (CD4⁺CD25⁺FoxP3⁺). Altogether, these results suggest that early differential immune activation is responsible for the heterogenous response to the combined treatment. Taken together, these studies for the first time provided insight into the additional mechanisms underlying radio-sensitization by 2-DG in vivo by unraveling its potential as an immune-modulator besides direct effects on the tumor.