Micromechanical Properties of Injection-Molded Starch–Wood Particle Composites

The micromechanical properties of injection molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples.Peer reviewe

Seeking Clarity within Cloudy Effluents: Differentiating Fungal from Bacterial Peritonitis in Peritoneal Dialysis Patients

Fungal peritonitis is a serious complication of peritoneal dialysis (PD) therapy with the majority of patients ceasing PD permanently. The aims of this study were to identify risk factors and clinical associations that may discriminate between fungal from bacterial peritonitis.We retrospectively identified episodes of fungal peritonitis from 2001-2010 in PD patients at Liverpool and Westmead Hospitals (Australia). Fungal peritonitis cases were matched in a 1:2 ratio with patients with bacterial peritonitis from each institution's dialysis registry, occurring closest in time to the fungal episode. Patient demographic, clinical and outcome data were obtained from the medical records.Thirty-nine episodes of fungal peritonitis (rate of 0.02 episodes per patient-year of dialysis) were matched with 78 episodes of bacterial peritonitis. Candida species were the commonest pathogens (35/39; 90% episodes) with Candida albicans (37%), Candida parapsilosis (32%) and Candida glabrata (13%) the most frequently isolated species. Compared to bacterial peritonitis, fungal peritonitis patients had received PD for significantly longer (1133 vs. 775 catheter-days; p = 0.016), were more likely to have had previous episodes of bacterial peritonitis (51% vs. 10%; p = 0.01), and to have received prior antibacterial therapy (51% vs. 10%; p = 0.01). Patients with fungal peritonitis were less likely to have fever and abdominal pain on presentation, but had higher rates of PD catheter removal (79% vs. 22%; p<0.005), and permanent transfer to haemodialysis (87% vs. 24%; p<0.005). Hospital length of stay was significantly longer in patients with fungal peritonitis (26.1 days vs. 12.6 days; p = 0.017), but the all-cause 30-day mortality rate was similar in both groups. Fluconazole was a suitable empiric antifungal agent; with no Candida resistance detected.Prompt recognition of clinical risk factors, initiation of antifungal therapy and removal of PD catheters are key considerations in optimising outcomes

Effect of cinacalcet on cardiovascular disease in patients undergoing dialysis

BACKGROUND: Disorders of mineral metabolism, including secondary hyperparathyroidism, are thought to contribute to extraskeletal (including vascular) calcification among patients with chronic kidney disease. It has been hypothesized that treatment with the calcimimetic agent cinacalcet might reduce the risk of death or nonfatal cardiovascular events in such patients. METHODS: In this clinical trial, we randomly assigned 3883 patients with moderate-to-severe secondary hyperparathyroidism (median level of intact parathyroid hormone, 693 pg per milliliter [10th to 90th percentile, 363 to 1694]) who were undergoing hemodialysis to receive either cinacalcet or placebo. All patients were eligible to receive conventional therapy, including phosphate binders, vitamin D sterols, or both. The patients were followed for up to 64 months. The primary composite end point was the time until death, myocardial infarction, hospitalization for unstable angina, heart failure, or a peripheral vascular event. The primary analysis was performed on the basis of the intention-to-treat principle. RESULTS: The median duration of study-drug exposure was 21.2 months in the cinacalcet group, versus 17.5 months in the placebo group. The primary composite end point was reached in 938 of 1948 patients (48.2%) in the cinacalcet group and 952 of 1935 patients (49.2%) in the placebo group (relative hazard in the cinacalcet group vs. the placebo group, 0.93; 95% confidence interval, 0.85 to 1.02; P = 0.11). Hypocalcemia and gastrointestinal adverse events were significantly more frequent in patients receiving cinacalcet. CONCLUSIONS: In an unadjusted intention-to-treat analysis, cinacalcet did not significantly reduce the risk of death or major cardiovascular events in patients with moderate-to-severe secondary hyperparathyroidism who were undergoing dialysis

Specific interactions of Bi(III) with Cys-Xaa-Cys unit of a peptide sequence

The medicinal application of bismuth compounds is focused in two fields: antimicrobial and anticancer. Bi(III) complexes have been used in medicine as an effective treatment of microbial infections, such as peptic ulcers, diarrhoea, gastritis and syphilis. 212Bi and 213Bi are strong a-particle emitters, which, bound to specific ligands, could be promising targeted radio-therapeutic agents for the treatment of cancer. In this work, the coordination of bismuth to three peptides with the Cys-Xaa-Cys motif was studied by potentiometric, spectroscopic, mass spectrometric and NMR methods. We have shown, that sulfur atoms from cysteines are critical donors for the coordination of Bi(III). Our investigation provides insight towards an understanding of the chemistry of bismuth-containing complexes and may lead to the further application of this metal in medicine

Metal Complexes of Two Specific Regions of ZnuA, a Periplasmic Zinc(II) Transporter from Escherichia coli

The crystal structure of ZnZnuA from Escherichia coli reveals two metal binding sites. (i) The primary binding site, His143, is located close the His-rich loop (residues 116–138) and plays a significant role in Zn­(II) acquisition. (ii) The secondary binding site involves His224. In this work, we focus on understanding the interactions of two metal ions, Zn­(II) and Cu­(II), with two regions of ZnuA, which are possible anchoring sites for Zn­(II): Ac-115MKSI­HGDD­DDHD­HAEK­SDED­HHHG­DFNM­HLW145-NH2 (primary metal binding site) and Ac-223GHFTV­NPEI­QPGA­QRL­HE240-NH2 (secondary metal binding site). The histidine-rich loop (residues 116–138) has a role in the capture of zinc­(II), which is then further delivered into other regions of the protein. For both Zn­(II) complexes, histidine residues constitute the main anchoring donors. In the longer, His-rich fragment, a tetrahedral complex with four His residues is formed, while in the second ligand, two imidazole nitrogens are involved in zinc­(II) binding. In both cases, so-called loop structures are formed. One consists of a 125HxHxE­xxx­ExHxH137 motif with seven amino acid residues in the loop between the two central histidines, while the other is formed by a 224HFTVN­PEIQP­GAQ­RLH239 motif with 14 amino acid residues in the loop between the two nearest coordinating histidines. The number of available imidazoles also strongly affects the structure of copper­(II) complexes; the more histidines in the studied region, the higher the pH in which amide nitrogens will participate in Cu­(II) binding

Heteronuclear and homonuclear Cu2+ and Zn2+ complexes with multihistidine peptides based on zebrafish prion-like protein

The homeostasis of metal ions, especially copper and zinc, is a major factor that may influence the prion diseases and the biological function of prion protein (PrP). The His-rich regions are basic sites for metal binding and antioxidant activity of the PrP structures. Animal prion-like proteins contain also His-rich domains, and their coordination chemistry may provide better insight into the chemistry and biology of PrP structures and related diseases. Herein, we report an equilibrium study on heteronuclear Zn2+-Cu2+ complexes with zrel-PrP fragments from zebrafish. Potentiometric, spectroscopic, and mass spectrometric methods showed that the binding of copper is much more effective than the binding of zinc. At physiological pH, both metals bind to the histidine imidazole N donors of the studied peptides