Experimental investigation of the governing parameters in the electrospinning of poly(3-hydroxybutyrate) scaffolds : structural characteristics of the pores

We sought to determine the impact of electrospinning parameters on a trustworthy criterion that could evidently improve the maximum applicability of fibrous scaffolds for tissue regeneration. We used an image analysis technique to elucidate the web permeability index (WPI) by modeling the formation of electrospun scaffolds. Poly(3-hydroxybutyrate) (P3HB) scaffolds were fabricated according to predetermined conditions of levels in a Taguchi orthogonal design. The material parameters were the polymer concentration, conductivity, and volatility of the solution. The processing parameters were the applied voltage and nozzle-to-collector distance. With a law to monitor the WPI values when the polymer concentration or the applied voltage was increased, the pore interconnectivity was decreased. The quality of the jet instability altered the pore numbers, areas, and other structural characteristics, all of which determined the scaffold porosity and aperture interconnectivity. An initial drastic increase was observed in the WPI values because of the chain entanglement phenomenon above a 6 wt % P3HB content. Although the solution mixture significantly (p < 0.05) changed the scaffold architectural characteristics as a function of the solution viscosity and surface tension, it had a minor impact on the WPI values. The solution mixture gained the third place of significance, and the distance was approved as the least important factor.

Effects of chronic intra-amniotic Ureaplasma parvum (serovar 3 and 6) colonization in the ovine fetus

Background: We have developed a sheep model of intrauterine ureaplasma infection. We aimed to examine the capability of ureaplasmas in the amniotic fluid to infect the fetus and alter fetal development...

Proton-transfer compounds with 4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (sulfamethazine): the structures and hydrogen-bonding in the salts with 5-nitrosalicylic acid and picric acid

The structures of the anhydrous proton-transfer compounds of the sulfa drug sulfamethazine with 5-nitrosalicylic acid and picric acid, namely 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2-hydroxy-5-nitrobenzoate, C12H15N4O2S(+)·C7H4NO4(-), (I), and 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2,4,6-trinitrophenolate, C12H15N4O2S(+)·C6H2N3O7(-), (II), respectively, have been determined. In the asymmetric unit of (I), there are two independent but conformationally similar cation-anion heterodimer pairs which are formed through duplex intermolecular N(+)-H...Ocarboxylate and N-H...Ocarboxylate hydrogen-bond pairs, giving a cyclic motif [graph set R2(2)(8)]. These heterodimers form separate and different non-associated substructures through aniline N-H...O hydrogen bonds, one one-dimensional, involving carboxylate O-atom acceptors, the other two-dimensional, involving both carboxylate and hydroxy O-atom acceptors. The overall two-dimensional structure is stabilized by π-π interactions between the pyrimidinium ring and the 5-nitrosalicylate ring in both heterodimers [minimum ring-centroid separation = 3.4580 (8) Å]. For picrate (II), the cation-anion interaction involves a slightly asymmetric chelating N-H...O R2(1)(6) hydrogen-bonding association with the phenolate O atom, together with peripheral conjoint R1(2)(6) interactions between the same N-H groups and O atoms of the ortho-related nitro groups. An inter-unit amine N-H...Osulfone hydrogen bond gives one-dimensional chains which extend along a and inter-associate through π-π interactions between the pyrimidinium rings [centroid-centroid separation = 3.4752 (9) Å]. The two structures reported here now bring to a total of four the crystallographically characterized examples of proton-transfer salts of sulfamethazine with strong organic acids.

The relationship between children's emotional and cognitive self-regulation at 2 to 3 years and prosocial behavior in the early years of school

This study used data from Growing Up in Australia: The Longitudinal Study of Australian Children (LSAC) to investigate how parent report of children’s emotional and cognitive regulation at age 2-3 years was associated with teacher ratings of children’s prosocial behaviors in the early years of school. A sample of 2,392 children was drawn from the LSAC Birth Cohort for the analyses. The analyses used structural equation modeling to estimate parameters of the relationships between key variables. Within the model, estimates of mother-reported emotional and cognitive regulation at age 2 to 3 years were significantly associated with teacher-reported prosocial behavior at 6 to 7 years. Emotional regulation was a slightly stronger indicator of prosocial behavior than cognitive regulation. Being female and from a family with a higher socioeconomic position were also associated with higher levels of prosocial behavior. Results are discussed in relation to the role of early childhood teachers in fostering children’s self-regulatory behaviors and in providing environments in which empathic and prosocial behaviors are modeled, guided, and scaffolded so that foundations are laid for caring behaviors to be understood and internalized by children.

Analysis of 3 common polymorphisms in the KCNK18 gene in an Australian migraine case-control cohort

Migraine is a common neurological disorder characterised by temporary disabling attacks of severe head pain and associated disturbances. There is significant evidence to suggest a genetic aetiology to the disease however few causal mutations have been conclusively linked to the migraine subtypes Migraine with (MA) or without Aura (MO). The Potassium Channel, Subfamily K, member 18 (KCNK18) gene, coding the potassium channel TRESK, is the first gene in which a rare mutation resulting in a non-functional truncated protein has been identified and causally linked to MA in a multigenerational family. In this study, three common polymorphisms in the KCNK18 gene were analysed for genetic variation in an Australian case-control migraine population consisting of 340 migraine cases and 345 controls. No association was observed for the polymorphisms examined with the migraine phenotype or with any haplotypes across the gene. Therefore even though the KCNK18 gene is the only gene to be causally linked to MA our studies indicate that common genetic variation in the gene is not a contributor to MA.

Neurons Activated During Fear Memory Consolidation and Reconsolidation are Mapped to a Common and New Topography in the Lateral Amygdala

A key question in neuroscience is how memory is selectively allocated to neural networks in the brain. This question remains a significant research challenge, in both rodent models and humans alike, because of the inherent difficulty in tracking and deciphering large, highly dimensional neuronal ensembles that support memory (i.e., the engram). In a previous study we showed that consolidation of a new fear memory is allocated to a common topography of amygdala neurons. When a consolidated memory is retrieved, it may enter a labile state, requiring reconsolidation for it to persist. What is not known is whether the original spatial allocation of a consolidated memory changes during reconsolidation. Knowledge about the spatial allocation of a memory, during consolidation and reconsolidation, provides fundamental insight into its core physical structure (i.e., the engram). Using design-based stereology, we operationally define reconsolidation by showing a nearly identical quantity of neurons in the dorsolateral amygdala (LAd) that expressed a plasticity-related protein, phosphorylated mitogen-activated protein kinase, following both memory acquisition and retrieval. Next, we confirm that Pavlovian fear conditioning recruits a stable, topographically organized population of activated neurons in the LAd. When the stored fear memory was briefly reactivated in the presence of the relevant conditioned stimulus, a similar topography of activated neurons was uncovered. In addition, we found evidence for activated neurons allocated to new regions of the LAd. These findings provide the first insight into the spatial allocation of a fear engram in the LAd, during its consolidation and reconsolidation phase.

The facile formation of silver dendritic structures in the absence of surfactants and their electrochemical and SERS properties

In this work a simple approach to the creation of highly dispersed electrocatalytically active silver microstructured dendrites on indium tin oxide in the absence of any surface modification or surfactant is presented. It is found that the addition of low concentrations of supporting electrolyte to the AgNO3 solution dramatically influences the morphology of electrodeposited silver which is independent of both the anion and the cation employed. The silver dendrites are characterized by SEM, XRD, XPS as well as by cyclic voltammetry under alkaline conditions. It is found that the surface oxide formation and removal processes are significantly influenced by the microstructured morphology of the silver electrodeposits compared to a smooth macrosized silver electrode. The facile formation of dendritic silver microstructures is also shown to be beneficial for the electrocatalytic oxidation of both formaldehyde and hydrazine and oxygen reduction. The formation of a continuous film of dendritic silver is also investigated for its SERS activity where the connectivity between the individual dendrites is found to be particularly important.

In vivo and in vitro models demonstrate a role for caveolin-1 in the pathogenesis of ischaemic acute renal failure

Caveolae and their proteins, the caveolins, transport macromolecules; compartmentalize signalling molecules; and are involved in various repair processes. There is little information regarding their role in the pathogenesis of significant renal syndromes such as acute renal failure (ARF). In this study, an in vivo rat model of 30 min bilateral renal ischaemia followed by reperfusion times from 4 h to 1 week was used to map the temporal and spatial association between caveolin-1 and tubular epithelial damage (desquamation, apoptosis, necrosis). An in vitro model of ischaemic ARF was also studied, where cultured renal tubular epithelial cells or arterial endothelial cells were subjected to injury initiators modelled on ischaemia-reperfusion (hypoxia, serum deprivation, free radical damage or hypoxia-hyperoxia). Expression of caveolin proteins was investigated using immunohistochemistry, immunoelectron microscopy, and immunoblots of whole cell, membrane or cytosol protein extracts. In vivo, healthy kidney had abundant caveolin-1 in vascular endothelial cells and also some expression in membrane surfaces of distal tubular epithelium. In the kidneys of ARF animals, punctate cytoplasmic localization of caveolin-1 was identified, with high intensity expression in injured proximal tubules that were losing basement membrane adhesion or were apoptotic, 24 h to 4 days after ischaemia-reperfusion. Western immunoblots indicated a marked increase in caveolin-1 expression in the cortex where some proximal tubular injury was located. In vitro, the main treatment-induced change in both cell types was translocation of caveolin-1 from the original plasma membrane site into membrane-associated sites in the cytoplasm. Overall, expression levels did not alter for whole cell extracts and the protein remained membrane-bound, as indicated by cell fractionation analyses. Caveolin-1 was also found to localize intensely within apoptotic cells. The results are indicative of a role for caveolin-1 in ARF-induced renal injury. Whether it functions for cell repair or death remains to be elucidated.

Interstellar molecules : Conversion or C3O-. to C3O in the gas phase

Neutral C3O has been prepared by collision induced neutralisation of the precursor radical anion formed by the reaction C-=C-CO-OEt --> C3O-. +EtO. . The similar neutralisaaion reionisation (-NR+) and charge reversal (CR) spectra of C3O-. indicate that the potential surfaces of C3O and C3O+. show favourable vertical Franck-Condon overlap, This suggests that the bond connectivities of anion, neutral and cation C3O are the same. Copyright (C) 1999 John Wiley & Sons, Ltd.

Fragmentation pathways of 2,3-dimethyl-2,3-dinitrobutane cations in the gas phase

2,3-Dimethyl-2,3-dinitrobutane (DMNB) is an explosive taggant added to plastic explosives during manufacture making them more susceptible to vapour-phase detection systems. In this study, the formation and detection of gas-phase \[M+H](+), \[M+Li](+), \[M+NH(4)](+) and \[M+Na](+) adducts of DMNB was achieved using electrospray ionisation on a triple quadrupole mass spectrometer. The \[M+H](+) ion abundance was found to have a strong dependence on ion source temperature, decreasing markedly at source temperatures above 50 degrees C. In contrast, the \[M+Na](+) ion demonstrated increasing ion abundance at source temperatures up to 105 degrees C. The relative susceptibility of DMNB adduct ions toward dissociation was investigated by collision-induced dissociation. Probable structures of product ions and mechanisms for unimolecular dissociation have been inferred based on fragmentation patterns from tandem mass (MS/MS) spectra of source-formed ions of normal and isotopically labelled DMNB, and quantum chemical calculations. Both thermal and collisional activation studies suggest that the \[M+Na](+) adduct ions are significantly more stable toward dissociation than their protonated analogues and, as a consequence, the former provide attractive targets for detection by contemporary rapid screening methods such as desorption electrospray ionisation mass spectrometry. Copyright (C) 2009 Commonwealth of Australia. Published by John Wiley & Sons, Ltd.

Electron capture of tetracyanoethylene oxide in the gas phase. Rearrangement of the parent radical anion to form [(NC)(3)C](-). A joint experimental and ab initio study

Capture of an electron by tetracyanoethylene oxide can initiate a number of decomposition pathways. One of these decompositions yields [(NC)3C]− as the ionic product. Ab initio calculations (at the B3LYP/6-31+G∗ level of theory) indicate that the formation of [(NC)3C]− is initiated by capture of an electron into the LUMO of tetracyanoethylene oxide to yield the anion radical [(NC)2C–O–C(CN)2]−· that undergoes internal nucleophilic substitution to form intermediate [(NC)3C–OCCN]−·. This intermediate dissociates to form [(NC)3C]− (m/z 90) as the ionic product. The radical (NC)3C· has an electron affinity of 4.0 eV (385 kJ mol−1). Ab initio calculations show that [(NC)3C]− is trigonal planar with the negative charge mainly on the nitrogens. A pictorial representation of this structure is the resonance structure formed from three degenerate contributing structures (NC)2–CCN−. The other product of the reaction is nominally (NCCO)·, but there is no definitive experimental evidence to indicate whether this radical survives intact, or decomposes to NC· and CO. The overall process [(NC)2C–O–C(CN)2]−· → [(NC)3C]− + (NCCO)· is calculated to be endothermic by 21 kJ mol−1 with an overall barrier of 268 kJ mol−1.

Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the dicarboxylic oxalic and adipic acid analogues

The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O+·C2HO4-·2H2O, (I), and with adipic acid, bis­(4-car­bam­oylpiperidinium) adipate dihydrate, 2C6H13N2O+·C6H8O42-·2H2O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carb­oxy­lic acid O-HOcarboxyl hydrogen-bonding inter­actions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N-HO hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N-HOcarboxyl hydrogen bonds, generating cyclic R43(10) and R32(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water mol­ecule. In the crystal structure, the two inversion-related cations are inter­linked through the two water mol­ecules, which act as acceptors in dual amide N-HOwater hydrogen bonds, to give a cyclic R42(8) association which is conjoined with an R44(12) motif. Further N-HOwater, water O-HOamide and piperidinium N-HOcarbox­yl hydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water mol­ecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide-amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

Base-induced decomposition of alkyl hydroperoxides in the gas phase. Part 3. Kinetics and dynamics in HO-+CH3OOH, C2H5OOH, and tert-C4H9OOH reactions

The E-CO(2) elimination reactions of alkyl hydroperoxides proceed via abstraction of an (x-hydrogen by a base: X- + (RRHCOOH)-R-1-H-2 -> HX + (RRC)-R-1-C-2=O + HO-. Efficiencies and product distributions for the reactions of the hydroxide anion with methyl, ethyl, and tert-butyl hydroperoxides are studied in the gas phase. On the basis of experiments using three isotopic analogues, HO- + CH3OOH, HO- + CD3OOH, and H18O- + CH3OOH. the overall intrinsic reaction efficiency is determined to be 80% or greater. The E(CO)2 decomposition is facile for these methylperoxide reactions, and predominates over competing proton transfer at the hydroperoxide moiety. The CH3CH2OOH reaction displays a similar E(CO)2 reactivity, whereas proton transfer and the formation of HOO- are the exclusive pathways observed for (CH3)(3)COOH, which has no (x-hydrogen. All results are consistent with the E-CO(2) mechanism, transition state structure, and reaction energy diagrams calculated using the hybrid density functional B3LYP approach. Isotope labeling for HO- + CH3OOH also reveals some interaction between H2O and HO- within the E(CO)2 product complex [H2O center dot center dot center dot CH2=O center dot center dot center dot HO-]. There is little evidence, however. for the formation of the most exothermic products H2O + CH2(OH)O-, which would arise from nuclephilic condensation of CH2=O and HO-. The results suggest that the product dynamics are not totally statistical but are rather direct after the E-CO(2) transition state. The larger HO- + CH3CH2OOH system displays more statistical behavior during complex dissociation.

Validity and reliability of the 3-day physical activity recall in Singaporean adolescents

Childhood obesity and physical inactivity are major health concerns for the Singaporean government (Ministry of Health, Singapore [MOH], 2001). Data from the 1998 Singaporean National Health Survey indicate that 10.8–14.7% of Singaporean children ages 6–16 years are either overweight or obese (MOH, 2001). Although true population estimates of youth physical activity are not available, descriptive epidemiological studies conducted in the 1990s suggest that a large percentage of school-aged children in Singapore fail to meet established guidelines for participation in physical activity...