Comparison of Hydroxyapatite/Poly(lactide-co-glycolide) and Hydroxyapatite/Polyethyleneimine Composite Scaffolds in Bone Regeneration of Swine Mandibular Critical Size Defects: In Vivo Study

Reconstruction of jaw bone defects present a significant problem because of specific aesthetic and functional requirements. Although widely used, the transplantation of standard autograft and allograft materials is still associated with significant constraints. Composite scaffolds, combining advantages of biodegradable polymers with bioceramics, have potential to overcome limitations of standard grafts. Polyethyleneimine could be an interesting novel biocompatible polymer for scaffold construction due to its biocompatibility and chemical structure. To date, there have been no in vivo studies assessing biological properties of hydroxyapatite bioceramics scaffold modified with polyethyleneimine. The aim of this study was to evaluate in vivo effects of composite scaffolds of hydroxyapatite ceramics and poly(lactide-co-glycolide) and novel polyethyleneimine on bone repair in swine’s mandibular defects, and to compare them to conventional bone allograft (BioOss). Scaffolds were prepared using the method of polymer foam template in three steps. Pigs, 3 months old, were used and defects were made in the canine, premolar, and molar area of their mandibles. Four months following the surgical procedure, the bone was analyzed using radiological, histological, and gene expression techniques. Hydroxyapatite ceramics/polyethyleneimine composite scaffold demonstrated improved biological behavior compared to conventional allograft in treatment of swine’s mandibular defects, in terms of bone density and bone tissue histological characteristics.     

Electrocatalytic Behavior of an Amide Functionalized Mn(II) Coordination Polymer on ORR,OER and HER

The new 3D coordination polymer (CP) [Mn(L)(HCOO)]_n (Mn-CP) [L = 4-(pyridin-4-ylcarbamoyl)benzoate] was synthesised via a hydrothermal reaction using the pyridyl amide functionalized benzoic acid HL. It was characterized by elemental, FT-IR spectroscopy, single-crystal and powder X-ray diffraction (PXRD) analyses. Its structural features were disclosed by single-crystal X-ray diffraction analysis, which revealed a 3D structure with the monoclinic space group P21/c. Its performance as an electrocatalyst for oxygen reduction (ORR), oxygen evolution (OER), and hydrogen evolution (HER) reactions was tested in both acidic (0.5 M H₂SO₄) and alkaline (0.1 M KOH) media. A distinct reduction peak was observed at 0.53 V vs. RHE in 0.1 M KOH, which corresponds to the oxygen reduction, thus clearly demonstrating the material’s activity for the ORR. Tafel analysis revealed a Tafel slope of 101 mV dec⁻¹ with mixed kinetics of 2e⁻ and 4e⁻ pathways indicated by the Koutecky–Levich analysis. Conversely, the ORR peak was not present in 0.5 M H₂SO₄ indicating no activity of Mn-CP for this reaction in acidic media. In addition, Mn-CP demonstrated a noteworthy activity toward OER and HER in acidic media, in contrast to what was observed in 0.1 M KOH.     

Phytochemistry and Antihyperglycemic Potential of Cistus salviifolius L., Cistaceae

Cistus salviifolius has been previously reported as a traditional remedy for hyperglycemia. However, the plant has been scarcely investigated from scientific point of view. Thus, the aim was to examine the chemical composition and to evaluate its antioxidant and antihyperglycemic potential in vitro. Aqueous and ethanolic extracts were evaluated for total phenolic, tannin, and flavonoid content using spectrophotometric methods. Detailed chemical characterization was performed by high-performance liquid chromatography (HPLC-DAD). The volatile organic compounds (VOCs) profile was assessed by gas chromatography technique. The potential in diabetes treatment was evaluated through tests of free radicals neutralization, inhibition of lipid peroxidation process, and test of ferric ion reduction; activity in tests of inhibition of α-amylase, α-glucosidase and dipeptidyl peptidase-4 was also evaluated. High content of phenolics (majority being tannins) was detected; detailed HPLC analysis revealed high content of gallic acid, followed by rutin, chlorogenic and caffeic acids. The VOCs analysis determined sesquiterpene hydrocarbons and oxygenated sesquiterpenes as the main groups of compounds. The assays classified extracts as potent neutralizers of 2,2-diphenyl-1-picrylhydrazil and nitroso radicals formation and potent inhibitors of α-amylase and α-glucosidase. In conclusion, Cistus salviifolius represents a rich source of phenolics and essential oil with sesquiterpenes. The established results suggested its promising antioxidant and antihyperglycemic activities.     

pH-Responsive Hydrogel Beads Based on Alginate, κ-Carrageenan and Poloxamer for Enhanced Curcumin,Natural Bioactive Compound,Encapsulation and Controlled Release Efficiency

Polyphenolic compounds are used for treating various diseases due to their antioxidant and anticancer properties. However, utilization of hydrophobic compounds is limited due to their low bioavailability. In order to achieve a greater application of hydrophobic bioactive compounds, hydrogel beads based on biopolymers can be used as carriers for their enhanced incorporation and controlled delivery. In this study, beads based on the biopolymers-κ-carrageenan, sodium alginate and poloxamer 407 were prepared for encapsulation of curcumin. The prepared beads were characterized using IR, SEM, TGA and DSC. The curcumin encapsulation efficiency in the developed beads was 95.74 ± 2.24%. The release kinetics of the curcumin was monitored in systems that simulate the oral delivery (pH 1.2 and 7.4) of curcumin. The drug release profiles of the prepared beads with curcumin indicated that the curcumin release was significantly increased compared with the dissolution of curcumin itself. The cumulative release of curcumin from the beads was achieved within 24 h, with a final release rate of 12.07% (gastric fluid) as well as 81.93% (intestinal fluid). Both the in vitro and in vivo studies showed that new hydrogel beads based on carbohydrates and poloxamer improved curcumin’s bioavailability, and they can be used as powerful carriers for the oral delivery of different hydrophobic nutraceuticals.     

3,5-Nonadiyne isolated from the rhizome of Cachrys ferulacea inhibits endogenous nitric oxide release by rat peritoneal macrophages

3,5-Nonadiyne, in vitro, selectively inhibits endogenous nitric oxide release (IC(50)=6.7+/-0.8 microM) by rat peritoneal macrophages at doses that do not inhibit T cell proliferation. 3,5-Nonadiyne was isolated from root essential oil of Cachrys ferulacea (L.) CALESTANI, synonym Prangos ferulacea (L.) LINDLEY, obtained by hydrodistillation and spectrometricaly identified unambiguously.     

Formation of hydroxamic acids promoted by metal ions. interaction of aldehyde carbonyl group with C-nitroso group in the presence of ferric ions

Formation of N-phenyl substituted hydroxamic acids in the reaction of formaldehyde with substituted mtrosobenzene is strongly catalysed by Fe³⁺ ions, which stabilize the transition state for the rate-controlling proton transfer from the carbon of nitrosocarbinolic cation intermediate leading to the product, hydroxamic acid     

Kinetics of the disproportionation reaction of HIO2 in acidic aqueous solutions

We review and discuss kinetic studies of the disproportionation reaction of iodous acid (HIO₂) in the presence of excess of Hg²⁺‐ions. The reactions are followed at different temperatures in water solution with strongly defined acidity. The rate constants of disproportionation are determined between 285 and 303 K based on kinetic data obtained under steady‐state conditions. The calculated rate constants increase with increasing temperature and acid concentration. The corresponding values of activation energy as well as enthalpy and entropy of activation for this reaction have been calculated. The enthalpy of activation as well as entropy is higher at higher sulfuric acid concentration. Also, it was considered that the values of Gibbs energy of formation of HgI⁺ are generated during the process. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 687–691, 2010     

A note on an inverse problem for lattice points

Let K⊆R² be a compact set such that K+Z²=R² and let K−K={a−b|a,b∈K}. We prove, via Algebraic Topology, that the integer points of the difference set of K, (K−K)∩Z², is not contained on the coordinate axes, Z×{0}∪{0}×Z. This result implies the negative answer to the inverse problem posed by M.B. Nathanson (2010) [5].     

Role of π-acceptor effects in controlling the lability of novel monofunctional Pt(II) and Pd(II) complexes: crystal structure of [Pt(tripyridinedimethane)Cl]Cl

The kinetics and mechanism of substitution reactions of novel monofunctional [Pt(tpdm)Cl](+) and [Pd(tpdm)Cl](+) complexes (where tpdm = tripyridinedimethane) and their aqua analogues with thiourea (tu), L-methionine (L-met), glutathione (GSH), and guanosine-5'-monophosphate (5'-GMP) were studied in 0.1 M NaClO(4) at pH = 2.5 (in the presence of 10 mM NaCl for reactions of the chlorido complexes). The reactivity of the investigated nucleophiles follows the order tu > l-met > GSH > 5'-GMP. The reported rate constants showed the higher reactivity of the Pd(II) complexes as well as the higher reactivity of the aqua complex than the corresponding chlorido complex. The negative values reported for the activation entropy as well as the activation volume confirmed an associative substitution mode. In addition, the molecular and crystal structure of [Pt(tpdm)Cl]Cl was determined by X-ray crystallography. The compound crystallizes in a monoclinic space group C2/c with two independent molecules of the complex and unit cell dimensions of a = 38.303(2) ?, b = 9.2555(5) ?, c = 27.586(2) ?, β = 133.573(1)°, and V = 7058.3(8) ?(3). The cationic complex [Pt(tpdm)Cl](+) exhibits square-planar coordination around the Pt(II) center. The lability of the [Pt(tpdm)Cl](+) complex is orders of magnitude lower than that of [Pt(terpyridine)Cl](+). Quantum chemical calculations were performed on the [Pt(tpdm)Cl](+) and [Pt(terpyridine)Cl](+) complexes and their reactions with thiourea. Theoretical computations for the corresponding Ni(II) complexes clearly demonstrated that π-back-bonding properties of the terpyridine chelate can account for acceleration of the nucleophilic substitution process as compared to the tpdm chelate, where introduction of two methylene groups prevents such an effective π-back bonding.