Zinc mediated azide-alkyne ligation to 1,5- and 1,4,5-substituted 1,2,3-triazoles

A mild method for regioselective formation of 1,5-substituted 1,2,3-triazoles is described. The zinc-mediated reaction works at room temperature and is successful across a wide range of azido/alkynyl substrates. Additionally, the triazole 4-position can be further functionalized through the intermediate aryl-zinc to accommodate a diverse three-component coupling strategy.

A flow reactor process for the synthesis of peptides utilizing immobilized reagents, scavengers and catch and release protocols

A general flow process for the multi-step assembly of peptides has been developed and this procedure has been used to successfully construct a series of Boc, Cbz and Fmoc N-protected dipeptides in excellent yields and purities, including an extension of the method to enable the preparation of a tripeptide derivative.

Temporal sensitivity of rice seed development from spikelet fertility to viable mature seed to extreme-temperature

Extreme temperature during reproductive development affects rice (Oryza sativa L.) yield and seed quality. A controlled-environment reciprocal-transfer experiment was designed where plants from two japonica cultivars were grown at 28/24 ⁰C and moved to 18/14 ⁰C and vice versa, or from 28/24 to 38/34 ⁰C and vice versa, for 7-d periods to determine the respective temporal pattern of sensitivity of spikelet fertility, yield, and seed viability to each temperature extreme. Spikelet fertility and seed yield per panicle were severely reduced by extreme temperature in the 14 d period prior to anthesis; and both cultivars were affected at 38/34 ⁰C while only cv. Gleva was affected at 18/14 ºC. The damage was greater the earlier the panicles were stressed within this period. Later-exserted panicles compensated only partly for yield loss. Seed viability was significantly reduced by 7-d exposure to 38/34 ⁰C or 18/14 ⁰C at 1 to 7 and 1 to 14 d after anthesis, respectively, in cv. Gleva. Cultivar Taipei 309 was not affected by 7 d exposure at 18/14 ⁰C; and no consistent temporal pattern of sensitivity was evident at 38/34 ⁰C. Hence, brief exposure to low or high temperature was most damaging to spikelet fertility and yield 14 to 7 d before anthesis, coinciding with microsporogenesis; and it was almost as damaging around anthesis. Seed viability was most vulnerable to low or high temperature in the 7 or 14 d after anthesis, when histodifferentiation occurs.

Thiocyanate complexes of uranium in multiple oxidation states: a combined structural, magnetic, spectroscopic, spectroelectrochemical, and theoretical study

A comprehensive study of the complexes A4[U(NCS)8] (A = Cs, Et4N, nBu4N) and A3[UO2(NCS)5] (A = Cs, Et4N) is described, with the crystal structures of [nBu4N]4[U(NCS)8]·2MeCN and Cs3[UO2(NCS)5]·O0.5 reported. The magnetic properties of square antiprismatic Cs4[U(NCS)8] and cubic [Et4N]4[U(NCS)8] have been probed by SQUID magnetometry. The geometry has an important impact on the low-temperature magnetic moments: at 2 K, μeff = 1.21 μB and 0.53 μB, respectively. Electronic absorption and photoluminescence spectra of the uranium(IV) compounds have been measured. The redox chemistry of [Et4N]4[U(NCS)8] has been explored using IR and UV–vis spectroelectrochemical methods. Reversible 1-electron oxidation of one of the coordinated thiocyanate ligands occurs at +0.22 V vs Fc/Fc+, followed by an irreversible oxidation to form dithiocyanogen (NCS)2 which upon back reduction regenerates thiocyanate anions coordinating to UO22+. NBO calculations agree with the experimental spectra, suggesting that the initial electron loss of [U(NCS)8]4– is delocalized over all NCS– ligands. Reduction of the uranyl(VI) complex [Et4N]3[UO2(NCS)5] to uranyl(V) is accompanied by immediate disproportionation and has only been studied by DFT methods. The bonding in [An(NCS)8]4– (An = Th, U) and [UO2(NCS)5]3– has been explored by a combination of DFT and QTAIM analysis, and the U–N bonds are predominantly ionic, with the uranyl(V) species more ionic that the uranyl(VI) ion. Additionally, the U(IV)–NCS ion is more ionic than what was found for U(IV)–Cl complexes.

Bank loan terms and conditions: is there a macro effect?

We examine whether macroeconomic factors contain significant information for bank loan contracting terms and conditions (T&Cs), over and above that of standard firm-specific or country-level institutional factors. Our estimation is based on a seemingly unrelated mixed-processes methodology that accommodates two salient data properties: (i) the fact that loan contract terms are determined jointly as a single lending contract, and (ii) the fact that the elements of loan T&Cs are generated by different distributional formats. Our findings indicate that cross-country variation accounts for a significant portion of observed variation in loan T&Cs. In addition, macroeconomic fundamentals significantly explain the “package” of loan T&Cs offered to corporate borrowers, with this effect being distinct from any influence that T&Cs receive from firm-specific factors, and also from country-specific institutional factors.

Optimization of amaranth flour films plasticized with glycerol and sorbitol by multi-response analysis

The optimal formulation for the preparation of amaranth flour films plasticized with glycerol and sorbitol was obtained by a multi-response analysis. The optimization aimed to achieve films with higher resistance to break, moderate elongation and lower solubility in water. The influence of plasticizer concentration (Cg, glycerol or Cs, sorbitol) and process temperature (Tp) on the mechanical properties and solubility of the amaranth flour films was initially studied by response surface methodology (RSM). The optimized conditions obtained were Cg 20.02 g glycerol/100 g flour and Tp 75 degrees C, and Cs 29.6 g sorbitol/100 g flour and Tp 75 degrees C. Characterization of the films prepared with these formulations revealed that the optimization methodology employed in this work was satisfactory. Sorbitol was the most suitable plasticizer. It furnished amaranth flour films that were more resistant to break and less permeable to oxygen, due to its greater miscibility with the biopolymers present in the flour and its lower affinity for water. (C) 2011 Elsevier Ltd. All rights reserved.

Reduction of oil uptake in deep fat fried chicken nuggets using edible coatings based on cassava starch and methylcellulose

The aim of this study was to evaluate the effect of edible coatings based on methylcellulose (MC) and cassava starch (CS) to reduce oil uptake and improve water retention of chicken nuggets during deep fat frying. Edible coatings were prepared with I g of MC/100 g solution and 4 g of CS/100 g solution, with 25 or 55 g glycerol/100 g biopolymer. These solutions were applied to nugget samples before battering. Pre-fried and fried nuggets were analyzed to determine lipid and water contents. Color and texture were also measured in the fried nuggets. In general, there was no effect of the two concentrations of plasticizer of either of the biopolymers on the water retention of whole nuggets. But, higher oil uptake reduction, and consequently, lower lipid content was observed on nuggets coated with CS and 25% plasticizer. The coated samples were darker and had a brighter yellow color when compared with the control. There was also a significant decrease in the shearing force of the fried coated samples, indicating reduced hardness of these samples.

Rosiglitazone prevents sirolimus-induced hypomagnesemia, hypokalemia, and downregulation of NKCC2 protein expression

Alexandre CS, Braganca AC, Shimizu MH, Sanches TR, Fortes MA, Giorgi RR, Andrade L, Seguro AC. Rosiglitazone prevents sirolimus-induced hypomagnesemia, hypokalemia, and downregulation of NKCC2 protein expression. Am J Physiol Renal Physiol 297: F916-F922, 2009. First published August 5, 2009; doi:10.1152/ajprenal.90256.2008.-Sirolimus, an antiproliferative immunosuppressant, induces hypomagnesemia and hypokalemia. Rosiglitazone activates renal sodiumand water-reabsorptive pathways. We evaluated whether sirolimus induces renal wasting of magnesium and potassium, attempting to identify the tubule segments in which this occurs. We tested the hypothesis that reduced expression of the cotransporter NKCC2 forms the molecular basis of this effect and evaluated the possible association between increased urinary excretion of magnesium and renal expression of the epithelial Mg(2+) channel TRPM6. We then analyzed whether rosiglitazone attenuates these sirolimus-induced tubular effects. Wistar rats were treated for 14 days with sirolimus (3 mg/kg body wt in drinking water), with or without rosiglitazone (92 mg/kg body wt in food). Protein abundance of NKCC2, aquaporin2 (AQP2), and TRPM6 was assessed using immunoblotting. Sirolimus-treated animals presented no change in glomerular filtration rate, although there were marked decreases in plasma potassium and magnesium. Sirolimus treatment reduced expression of NKCC2, and this was accompanied by greater urinary excretion of sodium, potassium, and magnesium. In sirolimus-treated animals, AQP2 expression was reduced. Expression of TRPM6 was increased, which might represent a direct stimulatory effect of sirolimus or a compensatory response. The finding that rosiglitazone prevented or attenuated all sirolimus-induced renal tubular defects has potential clinical implications.

TOWARD UNDERSTANDING THE B[e] PHENOMENON. IV. MODELING OF IRAS 00470+6429

FS CMa type stars are a recently described group of objects with the B[e] phenomenon which exhibits strong emission-line spectra and strong IR excesses. In this paper, we report the first attempt for a detailed modeling of IRAS 00470+6429, for which we have the best set of observations. Our modeling is based on two key assumptions: the star has a main-sequence luminosity for its spectral type (B2) and the circumstellar (CS) envelope is bimodal, composed of a slowly outflowing disklike wind and a fast polar wind. Both outflows are assumed to be purely radial. We adopt a novel approach to describe the dust formation site in the wind that employs timescale arguments for grain condensation and a self-consistent solution for the dust destruction surface. With the above assumptions we were able to satisfactorily reproduce many observational properties of IRAS 00470+6429, including the Hi line profiles and the overall shape of the spectral energy distribution. Our adopted recipe for dust formation proved successful in reproducing the correct amount of dust formed in the CS envelope. Possible shortcomings of our model, as well as suggestions for future improvements, are discussed.

Caesium, potassium and ammonium distributions in different organs of tropical plants

In the present work the distribution of ions in aboveground plant parts was studied in order to establish the suitability of using radiocaesium as a tracer for the plant absorption of nutrients, such as potassium (K(+)) and ammonium (NH(4)(+)). We present the results for the distributions of (137)Cs, (40)K and NH(4)(+) from four tropical plant species: lemon (Citrus aurantifolia), orange (Citrus sinensis), guava (Psidium guajava) and chili pepper (Capsicum frutescens). Activity concentrations of (137)Cs and (40)K were measured by gamma spectrometry and concentrations of free NH(4)(+) ions by a colorimetric method. Similarly to potassium and ammonium, caesium showed a high mobility within the plants, exhibiting the highest values of concentration in the growing parts of the tree (fruits, new leaves, twigs, and barks). A significant correlation between activity concentrations of (137)Cs and (40)K was observed in these tropical plants. The K/Cs discrimination ratios were approximately equal to unity in different compartments of each individual plant, suggesting that caesium could be a good tracer for (40)K in tropical woody fruit species. Despite the similarity observed for the behaviour of caesium and ammonium in the newly grown plant compartments, (137)Cs was not well correlated with NH(4)(+). Significant temporal changes in the NH(4)(+) concentrations were observed during the development of fruits, while the (137)Cs activity concentration alterations were not of great importance, indicating, therefore, that Cs(+) and free NH(4)(+) ions could have distinct concentration ratios for each particular plant organ. (C) 2008 Elsevier B.V. All rights reserved.

Seasonal metabolic changes in a year-round reproductively active subtropical tree-frog (Hypsiboas prasinus)

Although seasonal metabolic variation in ectothermic tetrapods has been investigated primarily in the context of species showing some level of metabolic depression during winter, but several species of anurans maintain their activity patterns throughout the year in tropical and subtropical areas. The tree-frog Hypsiboas prasinus occurs in the subtropical Atlantic Forest and remains reproductively active during winter, at temperatures below 10 degrees C. We compared males calling in summer and winter, and found that males of H. prasinus exhibit seasonal adjustments in metabolic and morphometric variables. Individuals calling during winter were larger and showed higher resting metabolic rates than those calling during summer. Calling rates were not affected by season. Winter animals showed lower liver and heart activity level of citrate synthase (CS), partially compensated by larger liver mass. Winter individuals also showed higher activity Of pyruvate kinase (PK) and lower activity of CS in trunk muscles, and higher activity of CS in leg muscles. Winter metabolic adjustments seem to be achieved by both compensatory mechanisms to the lower environmental temperature and a seasonally oriented aerobic depression of several organs. The impact of seasonal metabolic changes on calling performance and the capacity of subtropical anurans for metabolic thermal acclimatization are also discussed. (C) 2008 Elsevier Inc. All rights reserved.

Acquisition of Pavlovian Fear Conditioning Using beta-Adrenoceptor Activation of the Dorsal Premammillary Nucleus as an Unconditioned Stimulus to Mimic Live Predator-Threat Exposure

In the present work, we sought to mimic the internal state changes in response to a predator threat by pharmacologically stimulating the brain circuit involved in mediating predator fear responses, and explored whether this stimulation would be a valuable unconditioned stimulus (US) in an olfactory fear conditioning paradigm (OFC). The dorsal premammillary nucleus (PMd) is a key brain structure in the neural processing of anti-predatory defensive behavior and has also been shown to mediate the acquisition and expression of anti-predatory contextual conditioning fear responses. Rats were conditioned by pairing the US, which was an intra-PMd microinjection of isoproterenol (ISO; beta-adrenoceptor agonist), with amyl acetate odor-the conditioned stimulus (CS). ISO (10 and 40 nmol) induced the acquisition of the OFC and the second-order association by activation of beta-1 receptors in the PMd. Furthermore, similar to what had been found for contextual conditioning to a predator threat, atenolol (beta-1 receptor antagonist) in the PMd also impaired the acquisition and expression of OFC promoted by ISO. Considering the strong glutamatergic projections from the PMd to the dorsal periaqueductal gray (dPAG), we tested how the glutamatergic blockade of the dPAG would interfere with the OFC induced by ISO. Accordingly, microinjections of NMDA receptor antagonist (AP5, 6 nmol) into the dPAG were able to block both the acquisition, and partially, the expression of the OFC. In conclusion, we have found that PMd beta-1 adrenergic stimulation is a good model to mimic predatory threat-induced internal state changes, and works as a US able to mobilize the same systems involved in the acquisition and expression of predator-related contextual conditioning. Neuropsychopharmacology (2011) 36, 926-939; doi:10.1038/npp.2010.231; published online 5 January 2011

Sensing danger through the olfactory system: The role of the hypothalamic dorsal premammillary nucleus

The dorsal premammillary nucleus (PMd) has a critical role on the expression of defensive responses to predator odor. Anatomical evidence suggests that the PMd should also modulate memory processing through a projecting branch to the anterior thalamus. By using a pharmacological blockade of the PMd with the NMDA-receptor antagonist 2-amino-5-phosphonopentanoic acid (AP5), we were able to confirm its role in the expression of unconditioned defensive responses, and further revealed that the nucleus is also involved in influencing associative mechanisms linking predatory threats to the related context. We have also tested whether olfactory fear conditioning, using coffee odor as CS, would be useful to model predator odor. Similar to cat odor, shock-paired coffee odor produced robust defensive behavior during exposure to the odor and to the associated context. Shock-paired coffee odor also up-regulated Fos expression in the PMd, and, as with cat odor, we showed that this nucleus is involved in the conditioned defensive responses to the shock-paired coffee odor and the contextual responses to the associated environment. (C) 2008 Elsevier Ltd. All rights reserved.

Effect of the anti-neoplastic drug doxorubicin on XPD-mutated DNA repair-deficient human cells

Doxorubicin (DOX), a member of the anthracycline group, is a widely used drug in cancer therapy. The mechanisms of DOX action include topoisomerase II-poisoning, free radical release, DNA adducts and interstrand cross-link (ICL) formation. Nucleotide excision repair(NER) is involved in the removal of helix-distorting lesions and chemical adducts, however, little is known about the response of NER-deficient cell lines to anti-tumoral drugs like DOX. Wild type and XPD-mutated cells, harbouring mutations in different regions of this gene and leading to XP-D, XP/CS or TTD diseases, were treated with this drug and analyzed for cell cycle arrest and DNA damage by comet assay. The formation of DSBs was also investigated by determination of gamma H2AX foci. Our results indicate that all three NER-deficient cell lines tested are more sensitive to DOX treatment, when compared to wild type cells or XP cells complemented by the wild type XPD cDNA, suggesting that NER is involved in the removal of DOX-induced lesions. The cell cycle analysis showed the characteristic G2 arrest in repair-proficient MRC5 cell line after DOX treatment, whereas the repair-deficient cell lines presented significant increase in sub-G1 fraction. The NER-deficient cell lines do not show different patterns of DNA damage formation as assayed by comet assay and phosphorylated H2AX foci formation. Knock-down of topoisomerase II alpha with siRNA leads to increased survival in both MRC5 and XP cells, however, XP cell line still remained significantly more sensitive to the treatment by DOX. Our study suggests that the enhanced sensitivity is due to DOX-induced DNA damage that is subject to NER, as we observed decreased unscheduled DNA synthesis in XP-deficient cells upon DOX treatment. Furthermore, the complementation of the XPD-function abolished the observed sensitivity at lower DOX concentrations, suggesting that the XPD helicase activity is involved in the repair of DOX-induced lesions. (C) 2009 Elsevier B.V. All rights reserved.

CD8(+) T cell adjuvant effects of Salmonella FliCd flagellin in live vaccine vectors or as purified protein

Salmonella flagellin, the flagellum structural subunit, has received particular interest as a vaccine adjuvant conferring enhanced immunogenity to soluble proteins or peptides, both for activation of antibody and cellular immune responses. In the present study, we evaluated the Salmonella enterica FliCd flagellin as a T cell vaccine adjuvant using as model the 9-mer (SYVPSAEQI) synthetic H2(d)-restricted CD8(+) T cell-specific epitope (CS(280-288)) derived from the Plasmodium yoelii circumsporozoite (G) protein. The FliCd adjuvant effects were determined under two different conditions: (i) as recombinant flagella, expressed by orally delivered live S. Dublin vaccine strains expressing the target CS(280-288) peptide fused at the central hypervariable domain, and (ii) as purified protein in acellular vaccines in which flagellin was administered to mice either as a recombinant protein fused or admixed with the target CS(280-288) peptide. The results showed that CS(280-288)-specific cytotoxic CD8(+) T cells were primed when BALB/c mice were orally inoculated with the expressing the CS280-288 epitope S. Dublin vaccine strain. In contrast, mice immunized with purified FliCd admixed with the CS280-288 peptide and, to a lesser extent, fused with the target peptide developed specific cytotoxic CD8(+) T cell responses without the need of a heterologous booster immunization. The CD8(+) T cell adjuvant effects of flagellin, either fused or not with the target peptide, correlated with the in vivo activation of CD11c(+) dendritic cells. Taken together, the present results demonstrate that Salmonella flagellins are flexible adjuvant and induce adaptative immune responses when administered by different routes or vaccine formulations. (C) 2009 Elsevier Ltd. All rights reserved.