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Predominant Form (predominant + form)
Selected AbstractsPerformance of Impedimetric Biosensors Based on Anodically Formed Ti/TiO2 ElectrodesELECTROANALYSIS, Issue 20 2005Aikaterini Abstract The advantages and limitations of impedimetric sensors based on Ti/TiO2 architectures are described. Titanium dioxide (titania) was potentiostatically formed onto titanium electrodes of 2,mm diameter, at 10 and 30,V in 1,M H2SO4. The thickness of the titania layers was ellipsometrically determined to be 30 and 86,nm respectively and they are highly insulating with charge-transfer resistances in the M, range, as they were measured with electrochemical impedance spectroscopy under specific experimental conditions. Low voltage anodization (<10,V) results to amorphous TiO2, whereas at higher applied voltages (>25,V), anatase is the predominant form. SEM images are indicative of quite smooth, compact coatings without any severe cracks. [source] Development of a CE-MS method to analyze components of the potential biomarker vascular endothelial growth factor 165ELECTROPHORESIS, Issue 13 2009Angel Puerta Abstract The vascular endothelial growth factor 165 (VEGF165) is the predominant form of the complex VEGF-A family. Its angiogenic effect is involved in many physiological and pathological events. For this reason, its roles as a potential biomarker and as a therapeutic drug have been considered. Nevertheless, very little is known about the existence of different forms of VEGF165 arising from glycosylation and potentially from other PTMs. This aspect is important because different forms may differ in biological activity (therapeutic drug application) and the pattern of the different forms can vary with pathological changes (biomarker application). In this work a CE-MS method to separate up to seven peaks containing, at least, 19 isoforms of intact VEGF165 is described. Comparison between human VEGF165 expressed in a glycosylating system, i.e. insect cells, and in a non-glycosylating system, i.e. E. coli cells, has been carried out. The method developed provides structural information (mass fingerprint) about the different forms of VEGF165 and after the deconvolution and the analysis of the MS spectra, PTMs pattern of VEGF165 including glycosylation and loss of amino acids at the N- and C-terminus was identified. Glycans involved in PTMs promoting different glycoforms observed in the CE-MS fingerprint were confirmed by MALDI-MS after deglycosylation with peptide N-glycosidase F. This approach is a starting point to study the role of VEGF165 as a potential biomarker and to perform quality control of the drug during manufacturing. To our knowledge this is the first time that a CE-MS method for the analysis of VEGF165 has been developed. [source] Dose-dependent uptake, elimination, and toxicity of monosodium methanearsonate in adult zebra finches (Taeniopygia guttata)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2008Courtney A. Albert Abstract Monosodium methanearsonate (MSMA), an arsenic-based pesticide, has been used for the past 10 years in attempts to suppress mountain pine beetle (Dendroctonus ponderosae) outbreaks in British Columbia, Canada. Previous studies have shown that cavity nesting forest birds such as woodpeckers forage and breed in MSMA treated pine stands. Here we examined the effects of MSMA in the laboratory using the zebra finch (Taeniopygia guttata), with the objective to examine tissue distribution and sublethal toxic effects in a model avian species. Zebra finches were exposed to this pesticide at doses similar to those found in bark beetle samples from MSMA stands of trees treated in the southern interior of British Columbia (8, 24, and 72 ,g/g/d and a control group). Results showed high excretion (>90%) of arsenic in all dose groups, as well as dose-dependent trends in accumulation of arsenic in the blood (p < 0.001) and specific tissues. Monomethylarsonic acid, MMA (V), was the predominant form of arsenic in the blood plasma. Dimethylarsinic acid was the major form of arsenic found in the liver (83%) and kidney (61%) tissues. The brain tissue contained primarily the MMA (V) form (57%). Significant weight loss occurred in the two highest dose groups (p < 0.05). Birds in the highest dose group lost up to 15% of initial body mass. [source] Lysyl Hydroxylase-2b Directs Collagen Cross-Linking Pathways in MC3T3-E1 Cells,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2004Suchaya Pornprasertsuk Abstract To elucidate the roles of LH2b in collagen cross-linking, MC3T3-E1 cell clones expressing higher (S) or lower (AS) levels of LH2b were established. Compared with controls, the collagen cross-linking pattern was shifted toward hydroxylysine-aldehyde (S clones)- or lysine-aldehyde (AS clones)-derived pathways. The data indicate that LH2b directs collagen cross-linking pathways through its action on telopeptidyl lysine residues. Introduction: Lysine (Lys) hydroxylation is a post-translational modification of collagen critical for cross-linking and glycosylation. Currently, three isoforms of lysyl hydroxylase (LH) have been identified, but their specific functions are still not well defined. Recently, we proposed that LH2 might modulate collagen cross-linking pattern through its action on Lys residues located in the telopeptide domains of collagen. Materials and Methods: To directly test this hypothesis, several MC3T3-E1 cell-derived clones expressing higher (sense [S]) or lower (antisense [AS]) levels of LH2b, the predominant form of LH2 in this cell line, were established and cultured for 2 weeks, and collagen cross-links and precursor aldehydes in the matrices were analyzed. Results: In S clones tested, the ratio of dihydroxylysinonorleucine (DHLNL) to hydroxylysinonorleucine (HLNL) was significantly higher than the average of controls (76% and 140% increase, respectively), and the level of pyridinoline (Pyr) was elevated (100% and 150% increase, respectively). In contrast, when MC3T3-E1 cells were transfected with a LH2b antisense construct (AS clones), the DHLNL/HLNL ratios were significantly lower than that of controls (56% and 73% decrease, respectively), and Pyr was not detected. Furthermore, significant amounts of an aldol-derived cross-link, dehydrohistidinohydroxymerodesmosine, were produced (,0.3 mol/mol of collagen) in AS clones. Conclusions: The data clearly show a critical role of LH2b in determining collagen cross-linking pathways, most likely through its action on telopeptidyl Lys residues. [source] Estrogen modulates estrogen receptor , and , expression, osteogenic activity, and apoptosis in mesenchymal stem cells (MSCs) of osteoporotic miceJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S36 2001Shuanhu Zhou Abstract In the mouse, ovariectomy (OVX) leads to significant reductions in cancellous bone volume while estrogen (17,-estradiol, E2) replacement not only prevents bone loss but can increase bone formation. As the E2-dependent increase in bone formation would require the proliferation and differentiation of osteoblast precursors, we hypothesized that E2 regulates mesenchymal stem cells (MSCs) activity in mouse bone marrow. We therefore investigated proliferation, differentiation, apoptosis, and estrogen receptor (ER) , and , expression of primary culture MSCs isolated from OVX and sham-operated mice. MSCs, treated in vitro with 10,7 M E2, displayed a significant increase in ER, mRNA and protein expression as well as alkaline phosphatase (ALP) activity and proliferation rate. In contrast, E2 treatment resulted in a decrease in ER, mRNA and protein expression as well as apoptosis in both OVX and sham mice. E2 up-regulated the mRNA expression of osteogenic genes for ALP, collagen I, TGF-,1, BMP-2, and cbfa1 in MSCs. In a comparison of the relative mRNA expression and protein levels for two ER isoforms, ER, was the predominant form expressed in MSCs obtained from both OVX and sham-operated mice. Cumulatively, these results indicate that estrogen in vitro directly augments the proliferation and differentiation, ER, expression, osteogenic gene expression and, inhibits apoptosis and ER, expression in MSCs obtained from OVX and sham-operated mice. Co-expression of ER,, but not ER,, and osteogenic differentiation markers might indicate that ER, function as an activator and ER, function as a repressor in the osteogenic differentiation in MSCs. These results suggest that mouse MSCs are anabolic targets of estrogen action, via ER, activation. J. Cell. Biochem. Suppl. 36: 144,155, 2001. © 2001 Wiley-Liss, Inc. [source] Soil N dynamics in relation to leaf litter quality and soil fertility in north-western Patagonian forestsJOURNAL OF ECOLOGY, Issue 2 2003Patricia Satti Summary 1We examined the relationships among soil N dynamics, soil chemistry and leaf litter quality in 28 forest stands dominated by conifers, woody broad-leaf deciduous species or broad-leaf evergreens. Potential net N mineralization, net nitrification and microbial biomass N were used as indicators of soil N dynamics; pH, organic C, total N, exchangeable cations and extractable P as indicators of soil chemistry and N concentration, lignin concentration, C : N ratio and lignin : N ratio in senescent leaves as indicators of leaf litter quality. N dynamics were assessed in two consecutive years with contrasting precipitation. 2Net N mineralization was lower in stands of the three conifers and one of three broad-leaf evergreen species than in stands of the other six broad-leaf species (40,77 vs. 87,250 mg N kg,1 after 16-week incubations) and higher in the wetter year. 3The proportion of N nitrified was high beneath most species regardless of mineralization rates, soil N fertility and leaf litter quality, and was significantly higher for the wetter year. Ammonium was the predominant form of N in three sites affected by seasonal waterlogging and in two sites the predominant form changed from ammonium in the drier year to nitrate during the wetter year, probably due to differences in soil texture affecting soil moisture. 4Net N mineralization was linearly related to microbial biomass N, implying that the microbial activity per biomass unit was quite similar beneath all species. Constant microbial biomass during the wetter year suggested that as mineralization/nitrification increased, there was a higher potential risk of N losses. 5Although the litter lignin : N ratio allowed differentiation of soil N dynamics between broad-leaf species and conifers, its constant value (23,28) in all broad-leaf species made it a poor predictor of the differences found within this group. Across all sites and between broad-leaf species, soil N dynamics were best explained by a combination of leaf litter lignin and soil chemistry indicators, particularly soil total N for net N mineralization and net nitrification, and soil organic C for microbial biomass N. [source] Temporal changes in Sander vitreus egg thiamine levelsJOURNAL OF FISH BIOLOGY, Issue 4 2005M. E. Barnes Thiamine pyrophosphate was the predominant form of thiamine present initially in walleye Sander vitreus eggs from two spawning locations in Lake Oahe, South Dakota, U.S.A. Total thiamine content in the eggs at fertilization was 5·18 and 7·97 nmol g,1 for eggs from the Moreau and Grand River spawning sites respectively, and egg thiamine content in all its forms dropped dramatically at the next sampling period of 48 temperature units (TU). Thiamine values did not significantly drop after the 48 TU period, but mean total thiamine composition was < 0·9 nmol g,1 at the last sampling date (156 TU) just prior to hatching. [source] Quantification of Alzheimer pathology in ageing and dementia: age-related accumulation of amyloid-,(42) peptide in vascular dementiaNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 2 2006H. Lewis Clinicopathological observations suggest there is considerable overlap between vascular dementia (VaD) and Alzheimer's disease (AD). We used immunochemical methods to compare quantities of amyloid-, (A,) peptides in post mortem brain samples from VaD, AD subjects and nondemented ageing controls. Total A, peptides extracted from temporal and frontal cortices were quantified using a previously characterized sensitive homogenous time-resolved fluorescence (HTRF) assay. The HTRF assays and immunocapture mass spectrometric analyses revealed that the A,(42) species were by far the predominant form of extractable peptide compared with A,(40) peptide in VaD brains. The strong signal intensity for the peak representing A,(4,42) peptide confirmed that these N-terminally truncated species are relatively abundant. Absolute quantification by HTRF assay showed that the mean amount of total A,(42) recovered from VaD samples was approximately 50% of that in AD, and twice that in the age-matched controls. Linear correlation analysis further revealed an increased accumulation with age of both A, peptides in brains of VaD subjects and controls. Interestingly, VaD patients surviving beyond 80 years of age exhibited comparable A,(42) concentrations with those in AD in the temporal cortex. Our findings suggest that brain A, accumulates increasingly with age in VaD subjects more so than in elderly without cerebrovascular disease and support the notion that they acquire Alzheimer-like pathology in older age. [source] Seasonality and Wage Responsiveness in a Developing Agrarian EconomyOXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 2 2004Sunil Kanwar Abstract This paper studies the wage responsiveness of labour supply and demand, simultaneously addressing the twin issues of the non-clearing of developing rural labour markets and seasonality. It employs a data set pertaining to south-central India, and limits itself to the agricultural market for daily-rated labour (by far the predominant form of wage contract in the sample villages). Estimating a theoretically robust and empirically justified disequilibrium model of the agricultural labour market, we find no evidence of backward-bending supply curves or ,vertical' demand curves, contrary to findings in the literature. Further, while the agricultural labour market appears to be in equilibrium during the kharif (or rainy) season, it manifests excess supply in the rabi (or post-rainy) season. [source] Ring conformations and intermolecular interactions in two fused dibenzoazocinesACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Andrés F. Yepes 5-Acetyl-2-chloro-8,11-dimethyl-5,6,11,12-tetrahydrodibenzo[b,f]azocine, C19H20ClNO, (I), crystallizes as a single fully ordered isomer, but 14-acetyl-8,11-dimethyl-7,8,13,14-tetrahydrobenzo[f]naphtho[1,2- b]azocine,14-acetyl-8,9-dimethyl-7,8,13,14-tetrahydrobenzo[f]naphtho[1,2- b]azocine (74/26), C23H23NO, (II), exhibits threefold whole-molecule disorder involving both configurational and structural isomers. In (I) and in the predominant form of (II), the azocine rings adopt very similar conformations, forming boat-shaped rings having approximate twofold rotational symmetry. There are no direction-specific intermolecular interactions in the crystal structure of (I), but the molecules of (II) are weakly linked into chains by an aromatic ,,, stacking interaction. The compounds were made under green conditions using an acid-catalysed cyclization process having very high atom utilization. [source] Fracture analysis of composite co-cured structural joints using decohesion elementsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2004P. P. CAMANHO ABSTRACT Delamination is one of the predominant forms of failure in laminated composite structures, especially when there is no reinforcement in the thickness direction. To develop composite structures that are more damage tolerant, it is necessary to understand how delamination develops, and how it can affect the residual performance. A number of factors such as residual thermal stresses, matrix-curing shrinkage and manufacturing defects affect how damage will grow in a composite structure. It is important to develop computationally efficient analysis methods that can account for all such factors. The objective of the current work is to apply a newly developed decohesion element to investigate the debond strength of skin-stiffener composite specimens. The process of initiation of delaminations and the propagation of delamination fronts is investigated. The numerical predictions are compared with published experimental results. [source] The Remarkably High Prevalence of Epilepsy and Seizure History in Fetal Alcohol Spectrum DisordersALCOHOLISM, Issue 6 2010Stephanie H. Bell Background:, Fetal alcohol spectrum disorder (FASD) is the umbrella term that describes the range of adverse developmental outcomes that may occur in the offspring of mothers who drink alcohol during pregnancy. FASD is associated with several comorbidities including epilepsy. The objective of the study was to evaluate the prevalence of epilepsy or a history of seizures in subjects with FASD and the contribution of relevant risk factors. Methods:, A retrospective chart review was conducted on all active charts (N = 1063) at two FASD clinics. After exclusion of subjects without a confirmed diagnosis, a total of 425 subjects between the ages of 2,49 were included in the analysis. The relationships between FASD diagnosis and other risk factors for co-occurrence of epilepsy or a seizure disorder (e.g., extent of exposure to alcohol and other drugs, type of birth, and trauma) were examined using chi-square and multivariate multinomial logistic regression. Results:, Twenty-five (5.9%) individuals in the study population had a confirmed diagnosis of epilepsy, and 50 (11.8%) had at least one documented seizure episode, yielding an overall prevalence of 17.7% in this population. Importantly, a history of epilepsy or seizures was not different across the three diagnostic subgroups. In those subjects with available maternal drinking histories, first trimester exposure or drinking throughout all three trimesters were the predominant forms of fetal exposure. None of the other risk factors were associated with a greater prevalence of epilepsy or seizures. Conclusions:, There is a remarkably high prevalence of epilepsy/seizures in the FASD population. [source] | ||||||||||||||||