bluuebunny/crossref_metadata_2025_split huggingface dataset:
Voltammetry as a Virtual Potentiometric Sensor in Modelling of a Metal/Ligand System and Refinement of Stability Constants. Part 2
Authors: Cukrowski Ignacy , Zhang Jian Min , van Aswegen Anton 
Published: August 2004

AbstractA mathematical conversion of data from nonequilibrium and dynamic voltammetric techniques (direct‐current‐sampled (DC) and differential‐pulse (DP) polarography) into potentiometric, free‐metal‐ion sensor‐type data is described and employed in the study of BiIII complexes with the ligand picolinic acid (=pyridine‐2‐carboxylic acid) (labile and dynamic metal/ligand system). A novel procedure that allows evaluation of experimental data collected at very low pH values (acid‐base titration) is proposed. Software ESTA dedicated to potentiometry was successfully employed in the refinement operations performed with virtual potentiometric (VP) data obtained from DC and DP polarography, the latter being performed at fixed pH (ligand titration) as well as at fixed [LT]/[MT] ratio (acid‐base titration). It was possible to refine stability constants either separately from VP‐DC or VP‐DP, or simultaneously from any combination of VP‐DC and VP‐DP obtained from ligand and/or acid‐base titrations. The concept of VP‐DC or VP‐DP is employed for the first time in the study of an unknown BiIII/picolinic acid/OH system, and numerous documented and possible advantages are discussed. Five complexes of bismuth, ML, ML2, ML3, ML4, and ML3(OH) and their stability constants (as log β) 7.48±0.01, 13.94±0.01, 18.10±0.04, 20.47±0.25, and 26.65±0.03, respectively, are reported at 0.5M (Na,H)NO3 ionic strength and T 298 K. The proposed procedure can be easily utilized also by non‐electrochemists who are interested in, e.g., ligand‐design strategies.
Small‐animal models for testing macroporous ceramic bone substitutes
Authors: Le Guehennec L. , Goyenvalle E. , Aguado E , Houchmand‐Cuny M. , Enkel B. , Pilet P. , Daculsi G. , Layrolle P. 
Published: August 2004

AbstractThe aim of this study was to compare the bone colonization of a macroporous biphasic calcium phosphate (MBCP) ceramic in different sites (femur, tibia, and calvaria) in two animal species (rats and rabbits). A critical size defect model was used in all cases with implantation for 21 days. Bone colonization in the empty and MBCP‐filled defects was measured with the use of backscattered electron microscopy (BSEM). In the empty cavities, bone healing remained on the edges, and did not bridge the critical size defects. Bone growth was observed in all the implantation sites in rats (approx. 13.6–36.6% of the total defect area, with ceramic ranging from 46.1 to 51.9%). The bone colonization appeared statistically higher in the femur of rabbits (48.5%) than in the tibia (12.6%) and calvaria (22.9%) sites. This slightly higher degree of bone healing was related to differences in the bone architecture of the implantation sites. Concerning the comparison between animal species, bone colonization appeared greater in rabbits than in rats for the femoral site (48.5% vs. 29.6%). For the other two sites (the tibia and calvaria), there was no statistically significant difference. The increased bone ingrowth observed in rabbit femurs might be due to the large bone surface area in contact with the MBCP ceramics. The femoral epiphysis of rabbits is therefore a favorable model for testing the bone‐bonding capacity of materials, but a comparison with other implantation sites is subject to bias. This study shows that well‐conducted and fully validated models with the use of small animals are essential in the development of new bone substitutes. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 69–78, 2005
Analytical technique for quantification of selected resorbable calcium phosphate bone void fillers with the use of polarized‐light microscopy
Authors: Clineff Theodore D. , Erbe Erik M. , Bauer Thomas W. , Carroll Beth E. 
Published: August 2004

AbstractSynthetic calcium phosphate bone void fillers promote varying rates of bone formation and material resorption depending on chemistry, porosity, pore structure, and implant site. The objective of this study was to quantify the resorption of a novel ultraporous β‐tricalcium phosphate cancellous bone void filler with simultaneous quantification of bone formation in a canine humerus model. Potential measurement error involved in conventional histomorphometry using Von Kossa stains inspired the development of a new technique. This technique utilizes bright‐field and polarized‐light microscopy in conjunction with image analysis software, allowing more accurate histomorphometry. This technique was validated with two separate controlled experiments. Scanning electron microscopy further supported the results. The findings suggest that the use of polarized‐light microscopy combined with image analysis software can be an effective tool in simultaneously quantifying calcium phosphate resorption and bone formation. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 125–130, 2005
Quantum‐connectivity descriptors in modeling solubility of environmentally important organic compounds
Authors: Estrada Ernesto , Delgado Eduardo J. , Alderete Joel B. , Jaña Gonzalo A. 
Published: August 2004

AbstractQuantum‐connectivity indices are topographic descriptors combining quantum‐chemical and topological information. They are used to describe the water solubility of a noncongeneric data set of organic compounds. A QSPR model is obtained with two quantum‐connectivity indices that accounts for more than 90% of the variance in the water solubility of these chemicals. This model is compared to other five QSPR models using constitutional, electrostatic, geometric, quantum‐chemical, and topological descriptors calculated by CODESSA. None of these models accounts for more than 85% of the variance in water solubility of the compounds in this data set. The QSPR model obtained with quantum‐connectivity indices is also better than that generated from the general pool of 508 CODESSA indices. Models with up to five variables were explored and compared with the model obtained here. It is shown that quantum‐connectivity indices contain more structural information than other classes of descriptors at least for describing the water solubility of these 53 chemicals. Structural interpretation of the QSPR model developed as well as the role of the quantum‐connectivity indices included in it are also analyzed. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1787–1796, 2004
Jason Wagoner and Nathan A. Baker, "Solvation forces on biomolecular structures: A comparison of explicit solvent and Poisson‐Boltzmann models,"Journal of Computational Chemistry(2004) 25(13) 1623–1629
Authors: Wagoner Jason , Baker Nathan A. 
Published: August 2004

AbstractThe article to which this Erratum refers was published in Journal of Computational Chemistry (2004) 25(13) 1623–1629
Altered regulation of EGF receptor signaling following a partial hepatectomy
Authors: Skarpen E. , Oksvold M.P. , Grøsvik H. , Widnes C. , Huitfeldt H.S. 
Published: August 2004

AbstractWe have studied epidermal growth factor receptor (EGFR) phosphorylation and localization in the pre‐replicative phase of liver regeneration induced by a 70% partial hepatectomy (PH), and how a PH affects EGFR activation and trafficking. When Western blotting was performed on livers after PH with antibodies raised against activated forms of EGFR autophosphorylation sites, no marked increase in EGFR tyrosine phosphorylation was observed. However, events associated with attenuation of EGFR signals were observed. Two hours after PH, we found increased EGFR ubiquitination and internalization, followed by receptor downregulation. Furthermore, EGFR phosphorylation following an injection of EGF was reduced after PH. This reduction correlated with an increased activation of PKC and a distinct augmentation in the phosphorylation of the PKC‐regulated T654‐site of EGFR. When primary cultured hepatocytes were treated with tetradecanoylphorbol acetate (TPA) to induce T654‐phosphorylation of EGFR, we found colocalization of a fraction of EGFR with EEA1, downregulation of EGF‐mediated EGFR autophosphorylation, altered ligand‐induced intracellular sorting of EGFR, and increased mitogenic signaling through the EGFR‐Ras‐Raf‐ERK pathway. Further, we found that both TPA and a PH enhanced EGF‐induced proliferation of hepatocytes. In conclusion, our results suggest that hepatocyte priming involves modulation of EGFR that enhances its ability to mediate growth factor responses without an increase in its receptor tyrosine kinase‐activity. This may be a pre‐replicative competence event that increases growth factor effects during G1 progression. © 2004 Wiley‐Liss, Inc.
Interleukin (IL)‐1β toxicity to islet β cells: Efaroxan exerts a complete protection
Authors: Papaccio Gianpaolo , Graziano Antonio , Valiante Salvatore , D'Aquino Riccardo , Travali Salvatore , Nicoletti Ferdinando 
Published: August 2004

AbstractInterleukin (IL)‐1β‐treated rat islets of Langerhans were exposed in vitro either to the imidazoline compound, Efaroxan, or to the selective inducible nitric oxide synthase (iNOS) inhibitor, 1400W, in a medium containing a high concentration of glucose (16.7 mmol/L). Our data have evidenced the following: (i) addition of Efaroxan to islet cultures inhibited IL‐1β activation of ICE (cysteine protease IL‐1β converting enzyme) while addition of 1400W did not; (ii) Efaroxan completely inhibited IL‐1β‐induced suppression of insulin secretion and induction of iNOS mRNA transcripts, and, in addition, counteracted islet β‐cell protein profile alterations, Bax‐cytochrome c translocation, caspase activation, and apoptosis; (iii) 1400W inhibited IL‐1β induction of iNOS, but failed to completely counteract the other cytotoxic effects; (iv) the two compounds, moreover, exerted different effects on manganese superoxide dismutase (MnSOD), in fact, while Efaroxan inhibited the early stimulatory effect of IL‐1β on MnSOD, 1400W did not. Thus, Efaroxan completely protected islet β cells from damage caused by IL‐1β‐induced toxicity, while compound 1400W only inhibited NO radical production without altering the cytokine's cytotoxicity. Our observations have evidenced that suppression of ICE activation is required to counteract IL‐1β‐mediated islet β cell toxicity, and that IL‐1β‐induced apoptosis is NO‐independent and involves the cytochrome c‐mitochondrial pathway. © 2004 Wiley‐Liss, Inc.
Fermentation and oxygen transfer characteristics in serine alkaline protease production by recombinant Bacillus subtilis in molasses‐based complex medium
Authors: Çalık Güzide , Pehlivan Nur , Özçelik İlknur Şenver , Çalık Pınar , Özdamar Tunçer H 
Published: August 2004

AbstractSerine alkaline protease (SAP) production in a complex medium based on physically pretreated molasses by recombinant Bacillus subtilis carrying pHV1431::subC gene is described. The effects of oxygen transfer were investigated in 3.5 dm3 bioreactor systems with controls for agitation rate, dissolved oxygen, pH, temperature, and foam formation under two different agitation rates, ie N = 500 and 750 min−1, and four different air flow rates, ie Q/VR = 0.2, 0.5, 0.7, and 1.0 vvm, at a molasses concentration equivalent to initial sucrose concentration (CSo) of 20 kg m−3. The yield values (YX/S, YX/O, YS/O) and maintenance coefficient of oxygen (mO), were calculated. mO decreased with the increase in the air‐inlet rate. Increase in oxygen transfer rate increased the rate of growth and SAP activity, and affected the cultivation time to achieve maximum expression of SAP activity. At Q/VR = 0.5 vvm and N = 750 min−1, SAP activity reached 2250 U cm−3 at t = 36 h. The oxygen transfer coefficient (KLa) and oxygen uptake rate (−rO) were measured throughout the fermentations and their variation with the oxygen transfer conditions determined. New correlations for the calculation of KLa and −rO are proposed. Copyright © 2004 Society of Chemical Industry
Recovery and reuse of chromium from tannery wastewaters using Turbinaria ornata seaweed
Authors: Aravindhan Rathinam , Madhan Balaraman , Rao Jonnalagadda Raghava , Nair Balachandran Unni 
Published: August 2004

AbstractBrown seaweed (Turbinaria spp) was pre‐treated with sulfuric acid, calcium chloride and magnesium chloride and tested for its ability to remove chromium from tannery wastewater. Protonated seaweeds gave better uptake of chromium compared with calcium and magnesium treatments. Chromium uptake was optimal at pH 3.5. Turbinaria weed exhibited maximum uptake of about 31 mg of chromium for one gram of seaweed at an initial concentration of 1000 ppm of chromium. Freundlich and Langmuir adsorption isotherm models were used to describe the biosorption of chromium(III) by Turbinaria spp. The chromium‐loaded seaweed was reused as a reductant in the preparation of the tanning agent basic chromium sulfate (BCS). Leathers made from this tanning agent had properties comparable to conventionally processed chrome‐tanned leathers. Copyright © 2004 Society of Chemical Industry
Changes of gene expression profiles during neuronal differentiation of central nervous system precursors treated with ascorbic acid
Authors: Yu Dong‐Hyun , Lee Ki‐Hwan , Lee Ji‐Yeon , Kim Sujong , Shin Dong‐Mi , Kim Jin‐Hyuk , Lee Young‐Seek , Lee Yeon‐Sook , Oh Sun Kyung , Moon Shin Yong , Lee Sang‐Hun , Lee Yong‐Sung 
Published: August 2004

AbstractAscorbic acid (AA) has been shown to increase the yield of dopaminergic (DA) neurons derived from basic fibroblast growth factor (bFGF)‐expanded mesencephalic precursors. To understand the molecular mechanisms underlying this phenomenon, we used cDNA microarray analysis to examine differential expression of neuronal genes following AA treatment. The putative precursor cells were isolated from E13 rat ventral mesencephalons and expanded in the presence of bFGF. Cells were incubated in mitogen‐free media supplemented with 200 μM AA or were left untreated as a control, and total RNA was isolated at different time points (expansion stage and 1, 3, and 6 days after induction of differentiation) and subjected to cDNA microarray analysis. Differentiation was evaluated by Western blot analysis and immunocytochemistry of neuron‐specific markers. AA treatment of the mesencephalic precursors increased the expression of neuronal (MAP2) and astrocytic (glial fibrillary acidic protein) markers and the percentage of tyrosine hydroxylase (TH)‐positive cells. The microarray analysis revealed that 12 known genes were up‐regulated and 20 known genes were down‐regulated in expansion‐stage AA‐treated cells. Six days after the induction of differentiation, AA‐treated cells showed up‐regulation of 48 known genes and down‐regulation of 5 known genes. Our results identified several proteins, such as transferrin, S‐100, and somatostatin, as being differentially regulated in AA‐treated mesencephalic precursors. This novel result may lead to a better understanding of the molecular mechanisms underlying the AA‐induced differentiation of mesencephalic precursors into DA neurons and may form the basis for improved DA neuronal production for treatment of Parkinson's disease patients. © 2004 Wiley‐Liss, Inc.
Mitochondria‐derived oxidative stress induces a heat shock protein response
Authors: Barrett Matthew J. , Alones Vinessa , Wang Kai Xuan , Phan Lien , Swerdlow Russell H. 
Published: August 2004

AbstractIn addition to minimizing native and non‐native protein aggregations, heat shock proteins (HSPs) regulate programmed cell death pathways. Members of this conserved protein family are in general activated by oxidative stress, and likely help maintain viability under this stress condition. To further our understanding of heat shock protein physiology, we studied whether a specific subtype of oxidative stress, namely that arising from mitochondrial electron transport chain inhibition, induced a heat shock protein response. We exposed human teratocarcinoma (NT2) cells to varying concentrations of the cytochrome oxidase inhibitor sodium azide. Micromolar exposures resulted in a cytoplasm to nucleus translocation of the inducible Hsp70 and of Hsp40, and this was followed by an overall upregulation. The response did not coincide temporally with the onset of azide exposure, but rather was activated when the degree of cytochrome oxidase inhibition (which was progressive over time) surpassed a threshold. Azide did not affect either Hsp70 or Hsp40 dynamics in NT2 ρ0 cells, which lack functional electron transport chains. For the azide‐exposed native cell line, addition of the antioxidant trolox to the medium abrogated both Hsp70/Hsp40 translocation and upregulation. We conclude that mitochondrial electron transport chain dysfunction activates a heat shock protein response, and that this response is mediated by oxidative stress. © 2004 Wiley‐Liss, Inc.
N‐acetylcysteine prevents endotoxin‐induced degeneration of oligodendrocyte progenitors and hypomyelination in developing rat brain
Authors: Paintlia Manjeet K. , Paintlia Ajaib S. , Barbosa Ernest , Singh Inderjit , Singh Avtar K. 
Published: August 2004

AbstractPeriventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by diffuse white matter injury and is associated with cerebral palsy (CP). Maternal and placental infections are major causes of prematurity and identifiable etiology of PVL and CP. Here we have evaluated the therapeutic efficacy of N‐acetylcysteine (NAC), a potent antioxidant and precursor of glutathione, to attenuate lipopolysaccharide (LPS)‐induced white matter injury and hypomyelination in the developing rat brain, an animal model of PVL. Intraperitoneal pretreatment of pregnant female rats with NAC (50 mg/kg), 2 hr prior to administration of LPS at embryonic day 18 (E18), attenuated the LPS‐induced expression of inflammatory cytokines such as tumor necrosis factor‐α, interleukin‐1β, and inducible nitric oxide synthase in fetal rat brains. There were significantly reduced numbers of TUNEL+ nuclei coimmunostained for platelet‐derived growth factor‐αR+ [a surface marker for oligodendrocyte progenitor cells (OPCs)] at E20 in the subventricular zone of fetal rat brain in the NAC + LPS group compared with the untreated LPS group. Interestingly, immunostaining for O4 and O1 as markers for late OPCs and immature oligodendrocytes demonstrated fewer O4+ and O1+ cells in the LPS group compared with the NAC + LPS and control groups. Consistent with O4+/O1+ cell counts, the expression of myelin proteins such as myelin basic protein, proteolipid protein, and 2′3′‐cyclic nucleotide phosphodiesterase, including transcription factors such as MyT1 and Gtx, was less in the LPS group at late postnatal days, indicating severe hypomyelination in the developing rat brain when compared with NAC + LPS and control groups. Collectively, these data support the hypothesis that NAC may provide neuroprotection and attenuate the degeneration of OPCs against LPS evoked inflammatory response and white matter injury in developing rat brain. Moreover, these data suggest the possible use of NAC as a treatment for pregnant women with maternal or placental infection as a means of minimizing the risk of PVL and CP. © 2004 Wiley‐Liss, Inc.
Ternary complex with Trk, p75, and an ankyrin‐rich membrane spanning protein
Authors: Chang Mi‐Sook , Arevalo Juan Carlos , Chao Moses V. 
Published: August 2004

AbstractNeurotrophins play many critical roles in regulating neuronal plasticity, survival, and differentiation in the nervous system. Neurotrophins recognize two different receptors, the Trk receptor tyrosine kinase and the p75 neurotrophin receptor, which are associated closely. Several adaptor proteins are associated with each receptor. An ankyrin‐rich membrane spanning protein (ARMS), originally identified as a substrate for protein kinase D (Kidins220) and as a p75 interacting protein, serves as a novel downstream target of Trk receptor tyrosine kinases. Kidins220/ARMS is co‐expressed frequently with Trk and p75 and represents the only membrane‐associated protein known to interact with both receptors. We report here that a ternary complex can be formed between Trk, p75, and Kidins220/ARMS. The extracellular domains of the TrkA and the p75 receptors are necessary for their association, whereas the juxtamembrane region of p75 was responsible for the interaction with Kidins220/ARMS. Interestingly, increasing the level of Kidins220/ARMS expression resulted in a decreased association of TrkA with p75. These findings thus suggest that Kidins220/ARMS plays an important role in regulating interactions between Trk and p75 neurotrophin receptors. © 2004 Wiley‐Liss, Inc.
Effect of activation time on the nuclear remodeling and in vitro development of nuclear transfer embryos derived from bovine somatic cells
Authors: Choi Jong‐Yeob , Kim Choung‐Ik , Park Choon‐Keun , Yang Boo‐Keun , Cheong Hee‐Tae 
Published: August 2004

AbstractThis study was conducted to investigate the effect of recipient activation time on the chromatin structure and development of bovine nuclear transfer embryos. Serum‐starved skin cells were electrofused to enucleated oocytes, activated 1–5 hr after fusion, and cultured in vitro. Some fused eggs were fixed at each time point after fusion without activation, or 3 or 7 hr after activation. Some nocodazole treated zygotes were fixed to analyze their chromosome constitutions. The proportion of eggs with a morphologically normal premature chromosome condensation (PCC) state increased 1–2 hr after fusion. Whereas eggs with elongated chromosome plate increased as activation time was prolonged to 3 hr, and 5 hr after fusion, 58.1% of eggs showed more than two scattered chromosome sets. The proportion of eggs with a single chromatin mass (40.6–56.7%) significantly increased when eggs were activated within 2.5 hr after fusion (P < 0.05). Only 23.3% of reconstituted embryos activated 5 hr after fusion formed one pronucleus‐like structure (PN), whereas, 64.5–78.3% of embryos activated 1–2.5 hr after fusion formed one PN. The proportion of embryos with normal chromosome constitutions decreased as activation time was prolonged. Development rates to the blastocyst stage were higher in eggs activated within 2 hr after fusion (17.3–21.7%) compared to those of others (0–8.6%, P < 0.05). The result of the present study suggests that activation time can affect the chromatin structure and in vitro development of bovine nuclear transfer embryos. Mol. Reprod. Dev. 69: 289–295, 2004. © 2004 Wiley‐Liss, Inc.