bluuebunny/crossref_metadata_2025 huggingface dataset:
T cells are able to promote lipopolysaccharide‐induced bone resorption in mice in the absence of B cells
Authors: Yamaguchi M. , Ukai T. , Kaneko T. , Yoshinaga M. , Yokoyama M. , Ozaki Y. , Hara Y.
Published: July 2008

Background and Objective:  T cells and their cytokines are believed to be key factors in periodontal disease and bone resorption. We previously showed that T cells transferred to nude mice were related to inflammatory bone resorption in vivo. However, it has not been clarified whether T cells can induce bone resorption in the absence of B cells. In this study, we therefore investigated the ability of T cells to induce bone resorption without B cells, using both T cell‐ and B cell‐deficient mice with severe combined immune deficiency (SCID).

Material and Methods:  Escherichia coli lipopolysaccharide (LPS) was injected into the gingivae of SCID mice reconstituted by T cells (SCID + T mice). Wild‐type C.B‐17 mice and SCID mice were used as control animals. Alveolar bone resorption and production of cytokines in the gingivae were then compared histopathologically and immunohistologically.

Results:  The degree of bone resorption in SCID + T mice was significantly greater than that in SCID mice but less than that in wild‐type mice. The same tendency was found for expression of receptor activator of nuclear factor κB ligand. The number of interferon‐γ‐positive cells in SCID + T mice was the highest of the three groups. In contrast, interleukin‐4‐positive cells were detected in wild‐type mice but not in SCID + T and SCID mice.

Conclusion:  The results suggest that T cells are able to promote LPS‐induced bone resorption in the absence of B cells. The expressions of cytokines in the presence of B cells are quite different.
Subculture affects the phenotypic expression of human periodontal ligament cells and their response to fibroblast growth factor‐2 and bone morphogenetic protein‐7 in vitro
Authors: Lossdörfer S. , Fiekens D. , Salik M. I. , Götz W. , Jäger A.
Published: July 2008

Background and Objective:  Although periodontal ligament cells display several osteoblastic traits, their phenotypic expression is still not well established. It remains a matter of debate whether they resemble a terminally differentiated cell type or an intermediate maturation state that potentially can be directed towards a fibroblastic or an osteoblastic phenotype.

Material and Methods:  To explore the characteristics of periodontal ligament cells in greater detail, fourth‐passage, sixth‐passage and eighth‐passage human periodontal ligament cells were cultured for up to 3 wk. Ki‐67, alkaline phosphatase, osteocalcin, osteoprotegerin and receptor activator of nuclear factor‐κB ligand (RANKL) mRNA expression was quantified by real‐time polymerase chain reaction. Furthermore, the cellular response to fibroblast growth factor‐2 and bone morphogenetic protein‐7 was examined in first‐passage and fourth‐passage cells. Dermal fibroblasts (1BR.3.G) and osteoblast‐like cells (MG63) served as reference cell lines.

Results:  Proliferation decreased over time and was highest in fourth‐passage cells. The expression of differentiation parameters, osteoprotegerin and RANKL increased with culture time and was higher in fourth‐passage cells than in cells of later passages. The RANKL/osteoprotegerin ratio increased steadily until day 21. Administration of fibroblast growth factor‐2 enhanced cell numbers in both passages, whereas alkaline phosphatase and osteocalcin production remained unchanged. By contrast, exposure of periodontal ligament cells to bone morphogenetic protein‐7 resulted in a reduction of cell number in the first and fourth passages, whereas the production of alkaline phosphatase and osteocalcin was enhanced. In dermal fibroblasts, differentiation parameters did not respond to both stimuli. MG63 cells behaved similarly to periodontal ligament cells.

Conclusion:  These results indicate that subculture affects the phenotypic expression of human periodontal ligament cells with respect to the characteristics that these cells share with osteoblasts. Furthermore, the periodontal ligament cell phenotype can be altered by fibroblastic and osteoblastic growth factors.
Analysis of the association of polymorphism in the osteoprotegerin gene with susceptibility to chronic kidney disease and periodontitis
Authors: Baioni C. S. , De Souza C. M. , Ribeiro Braosi A. P. , Luczyszyn S. M. , Dias da Silva M. A. , Ignácio S. A. , Naval Machado M. Â. , Benato Martins W. D. , Riella M. C. , Pecoits‐Filho R. , Trevilatto P. C.
Published: July 2008

Background and Objective:  Chronic kidney disease (CKD) is a complex disorder, which results in several complications involving disturbance of mineral metabolism. Periodontal disease is an infectious disease that appears to be an important cause of systemic inflammation in CKD patients. Periodontal disease is characterized by clinical attachment loss (CAL) caused by alveolar bone resorption around teeth, which may lead to tooth loss. Osteoprotegerin (OPG) is a key regulator of osteoclastogenesis. Polymorphisms are the main source of genetic variation, and single nucleotide polymorphisms (SNPs) have been reported as major modulators of disease susceptibility. The aim of this study was to investigate the association of a polymorphism located at position –223 in the untranslated region of the OPG gene, previously known as –950, with susceptibility to CKD and periodontal disease.

Material and Methods:  A sample of 224 subjects without and with CKD (in hemodialysis) was divided into groups with and without periodontal disease. The OPG polymorphism was analyzed by polymerase chain reaction and restriction fragment length polymorphism.

Results:  No association was found between the studied OPG polymorphism and susceptibility to CKD or periodontal disease.

Conclusion:  It was concluded that polymorphism OPG–223 (C/T) was not associated with CKD and periodontal disease in a Brazilian population. Studies on other polymorphisms in this and other genes of the host response could help to clarify the involvement of bone metabolism mediators in the susceptibility to CKD and periodontal disease.
Expression of metalloproteinases and their tissue inhibitors in inflamed gingival biopsies
Authors: Gonçalves L. D. R. , Oliveira G. , Hurtado P. A. , Feitosa A. , Takiya C. M. , Granjeiro J. M. , Trackman P. C. , Otazú I. , Feres‐Filho E. J.
Published: July 2008

Objectives:  Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are known to be involved in the periodontal disease process. Results of in vivo MMPs and TIMPs gene expressions in the gingiva, though, are still controversial. In the present study, we compared the gene expression of MMP‐1, ‐2, ‐9, ‐13 and TIMP‐1, ‐2 in healthy and inflamed gingiva.

Methods:  38 gingival samples were collected from gingivitis (n = 10), advanced chronic periodontitis (n = 10), generalized aggressive periodontitis (n = 8) and periodontally healthy individuals (n = 10). Total RNA isolated from those samples was subjected to reverse transcription followed by amplification by polymerase chain reaction (RT‐PCR). Products were visualized in agarose gels and quantified by optical densitometry. Samples were also processed for gelatin zymography and Western blotting for MMP‐2 and MMP‐9 in order to assess for post‐transcriptional MMP regulation at the protein level.

Results:  The frequencies and levels of transcripts encoding MMPs and TIMPs were found to be not significantly different among groups (p > 0.05, Fisher’s Exact and Kruskall‐Wallis tests). There is a trend towards higher MMP‐2 and ‐9 gelatinase activities in the inflamed samples, although not statistically significant. In contrast, zymography and Western blotting studies show that MMP‐2 is virtually absent in the chronic periodontitis group.

Conclusion:  These results could reflect a complex regulation of MMPs and TIMPs’ gene expression in the course of gingival inflammation. They also reveal a great biological diversity even among individuals with similar periodontal status.
Apical tooth germ cell‐conditioned medium enhances the differentiation of periodontal ligament stem cells into cementum/periodontal ligament‐like tissues
Authors: Yang Z‐H. , Zhang X‐J. , Dang N‐N. , Ma Z‐F. , Xu L. , Wu J‐J. , Sun Y‐J. , Duan Y‐Z. , Lin Z , Jin Y.
Published: July 2008

Background and Objective:  Limitations of current periodontal regeneration modalities in both predictability and extent of healing response, especially on new cementum and attachment formation, underscore the importance of restoring or providing a microenvironment that is capable of promoting the differentiatiation of periodontal ligament stem cells (PDLSCs) towards cementoblast‐like cells and the formation of cementum/periodontal ligament‐like tissues. The aim of this study was to investigate the biological effect of conditioned medium from developing apical tooth germ cells (APTG‐CM) on the differentiation and cementogenesis of PDLSCs both in vitro and in vivo.

Material and Methods:  Using the limiting dilution technique, single‐colony‐derived human PDLSCs were isolated and expanded to obtain homogeneous populations of PDLSCs. Morphological appearance, cell cycle analysis, bromodeoxyuridine incorporation, alkaline phosphatase (ALP) activity, mineralization behavior, gene expression of cementoblast phenotype and in vivo differentiation capacities of PDLSCs co‐cultured with APTG‐CM were evaluated.

Results:  The induced PDLSCs exhibited several characteristics of cementoblast lineages, as indicated by the morphological changes, increased proliferation, high ALP activity, and the expression of cementum‐related genes and calcified nodule formation in vitro. When transplanted into immunocompromised mice, the induced PDLSCs showed tissue‐regenerative capacity to produce cementum/periodontal ligament‐like structures, characterized by a layer of cementum‐like mineralized tissues and associated periodontal ligament‐like collagen fibers connecting with the newly formed cementum‐like deposits, whereas control, untreated PDLSCs transplants mainly formed connective tissues.

Conclusion:  Our findings suggest that APTG‐CM is able to provide a cementogenic microenvironment and induce differentiation of PDLSCs along the cementoblastic lineage. This has important implications for periodontal engineering.
Plant–pathogen interactions: what is proteomics telling us?
Authors: Mehta Angela , Brasileiro Ana C. M. , Souza Djair S. L. , Romano Eduardo , Campos Magnólia A. , Grossi‐de‐Sá Maria F. , Silva Marília S. , Franco Octávio L. , Fragoso Rodrigo R. , Bevitori Rosangela , Rocha Thales L.
Published: July 2008

Over the years, several studies have been performed to analyse plant–pathogen interactions. Recently, functional genomic strategies, including proteomics and transcriptomics, have contributed to the effort of defining gene and protein function and expression profiles. Using these ‘omic’ approaches, pathogenicity‐ and defence‐related genes and proteins expressed during phytopathogen infections have been identified and enormous datasets have been accumulated. However, the understanding of molecular plant–pathogen interactions is still an intriguing area of investigation. Proteomics has dramatically evolved in the pursuit of large‐scale functional assignment of candidate proteins and, by using this approach, several proteins expressed during phytopathogenic interactions have been identified. In this review, we highlight the proteins expressed during plant–virus, plant–bacterium, plant–fungus and plant–nematode interactions reported in proteomic studies, and discuss these findings considering the advantages and limitations of current proteomic tools.
Regulation of ERK1/2 phosphorylation by acute and chronic morphine – implications for the role of cAMP‐responsive element binding factor (CREB)‐dependent and Ets‐like protein‐1 (Elk‐1)‐dependent transcription; small interfering RNA‐based strategy
Authors: Ligeza Agnieszka , Wawrzczak‐Bargiela Agnieszka , Kaminska Dorota , Korostynski Michal , Przewlocki Ryszard
Published: July 2008

Extracellular signal‐regulated kinases (ERKs) have been shown to be activated by opioids and functionally linked to addiction. Morphine‐associated changes in ERK activity seem to be the characteristic features of opioid action. In this study, we observed a rapid and severe increase in ERK1/2 activity after a 5 min morphine treatment of HEK‐MOR cells (transfected with the rat μ‐opioid receptor MOR1) expressing μ‐opioid receptor. Cellular adaptations to chronic (72 h) morphine treatment were manifested by a slight and sustained increase in ERK1/2 activity. Withdrawal caused by an opioid receptor antagonist – naloxone – attenuated phosphorylation of ERK1/2. Little information is available on the precise mechanism of ERK activity regulation. Using RNA interference technology, we generated stably transfected cells with silenced expression of cAMP‐responsive element binding factor (CREB) and Ets‐like protein‐1 (Elk‐1) transcription factors, which are known targets for activated ERK1/2. In these cells, ERK1/2 activity regulation was altered. Silencing of CREB or Elk‐1 significantly increased ERK activation observed after 5 min of morphine stimulation. The initial level of activated ERKs in these cells was also augmented. Moreover, the cellular response to withdrawal signals and chronic opioid treatment was diminished. These differences suggest that both CREB‐dependent and Elk‐1‐dependent transcription contribute to the expression of proteins regulating morphine‐induced ERK activity (particular phosphatases, upstream kinases or their activatory proteins).
Structure‐guided alteration of coenzyme specificity of formate dehydrogenase by saturation mutagenesis to enable efficient utilization of NADP+
Authors: Andreadeli Aggeliki , Platis Dimitris , Tishkov Vladimir , Popov Vladimir , Labrou Nikolaos E.
Published: July 2008

Formate dehydrogenase from Candida boidinii (CboFDH) catalyses the oxidation of formate anion to carbon dioxide with concomitant reduction of NAD+ to NADH. CboFDH is highly specific to NAD+ and virtually fails to catalyze the reaction with NADP+. Based on structural information for CboFDH, the loop region between β‐sheet 7 and α‐helix 10 in the dinucleotide‐binding fold was predicted as a principal determinant of coenzyme specificity. Sequence alignment with other formate dehydrogenases revealed two residues (Asp195 and Tyr196) that could account for the observed coenzyme specificity. Positions 195 and 196 were subjected to two rounds of site‐saturation mutagenesis and screening and enabled the identification of a double mutant Asp195Gln/Tyr196His, which showed a more than 2 × 107‐fold improvement in overall catalytic efficiency with NADP+ and a more than 900‐fold decrease in the efficiency with NAD+ as cofactors. The results demonstrate that the combined polar interactions and steric factors comprise the main structural determinants responsible for coenzyme specificity. The double mutant Asp195Gln/Tyr196His was tested for practical applicability in a cofactor recycling system composed of cytochrome P450 monooxygenase from Bacillus subtilis, (CYP102A2), NADP+, formic acid and ω‐(p‐nitrophenyl)dodecanoic acid (12‐pNCA). Using a 1250‐fold excess of 12‐pNCA over NADP+ the first order rate constant was determined to be equal to kobs = 0.059 ± 0.004 min−1.
In vitro stimulatory effect of anti‐apoptotic seminal vesicle protein 4 on purified peroxidase enzymes
Authors: Metafora Vittoria , Stiuso Paola , Ferranti Pasquale , Giannattasio Angela , Dicitore Alessandra , Ravagnan Gianpietro , De Maria Salvatore , Pontoni Gabriele , Cartenì Maria , Metafora Salvatore
Published: July 2008

The enzymatic activities of purified horseradish peroxidase, selenium‐dependent glutathione peroxidase, thyroid peroxidase and myeloperoxidase, but not that of lactoperoxidase, were markedly enhanced when added into a reaction mixture containing 5 μm native seminal vesicle protein 4, a major protein secreted from rat seminal vesicle epithelium. A further increase of horseradish peroxidase activity was obtained using Ser58‐phosphorylated or acetylated seminal vesicle protein 4. The activating effect of native seminal vesicle protein 4 was highest (about 60‐fold) on horseradish peroxidase when 4‐chloro‐1‐naphtol was used as the electron donor substrate. The main kinetics parameters of the stimulatory effect on horseradish peroxidase were evaluated and the enzyme–electron donor substrate interaction was investigated by HPLC and electrospray‐MS. A native seminal vesicle protein 4/4‐chloro‐1‐naphtol noncovalent adduct was detected when the protein and 4‐chloro‐1‐naphtol were present in the appropriate molar ratio in the horseradish peroxidase‐catalyzed reaction. By contrast, no adducts were formed between native seminal vesicle protein 4 and horseradish peroxidase. This native seminal vesicle protein 4/4‐chloro‐1‐naphtol interaction might underlie the native seminal vesicle protein 4‐induced horseradish peroxidase stimulation. Furthermore, native seminal vesicle protein 4 was shown by spectrophotometric and electrospray‐MS analysis to interact with NADPH, an electron donor substrate of the selenium‐dependent glutathione peroxidase/glutathione reductase redox system, with formation of an adduct between them. Although further investigation is required to elucidate the mechanism of adduct formation, this interaction, probably by promoting the release of the NADPH electrons required for glutathione disulphide reduction, could explain the stimulatory effect of seminal vesicle protein 4 on mammalian peroxidases possibly involved in its physiological function on the selenium‐dependent glutathione peroxidase/glutathione reductase system. The biological significance of these properties of native seminal vesicle protein 4 might be related to its ability to downregulate reactive oxygen species and oxidative stress‐induced apoptosis.
Rhodanese–thioredoxin system and allyl sulfur compounds
Authors: Sabelli Renato , Iorio Egidio , De Martino Angelo , Podo Franca , Ricci Alessandro , Viticchiè Giuditta , Rotilio Giuseppe , Paci Maurizio , Melino Sonia
Published: July 2008

Sodium 2‐propenyl thiosulfate, a water‐soluble organo‐sulfane sulfur compound isolated from garlic, induces apoptosis in a number of cancer cells. The molecular mechanism of action of sodium 2‐propenyl thiosulfate has not been completely clarified. In this work we investigated, by in vivo and in vitro experiments, the effects of this compound on the expression and activity of rhodanese. Rhodanese is a protein belonging to a family of enzymes widely present in all phyla and reputed to play a number of distinct biological roles, such as cyanide detoxification, regeneration of iron–sulfur clusters and metabolism of sulfur sulfane compounds. The cytotoxic effects of sodium 2‐propenyl thiosulfate on HuT 78 cells were evaluated by flow cytometry and DNA fragmentation and by monitoring the progressive formation of mobile lipids by NMR spectroscopy. Sodium 2‐propenyl thiosulfate was also found to induce inhibition of the sulfurtransferase activity in tumor cells. Interestingly, in vitro experiments using fluorescence spectroscopy, kinetic studies and MS analysis showed that sodium 2‐propenyl thiosulfate was able to bind the sulfur‐free form of the rhodanese, inhibiting its thiosulfate:cyanide‐sulfurtransferase activity by thiolation of the catalytic cysteine. The activity of the enzyme was restored by thioredoxin in a concentration‐dependent and time‐dependent manner. Our results suggest an important involvement of the essential thioredoxin–thioredoxin reductase system in cancer cell cytotoxicity by organo‐sulfane sulfur compounds and highlight the correlation between apoptosis induced by these compounds and the damage to the mitochondrial enzymes involved in the repair of the Fe–S cluster and in the detoxification system.
Salt‐resistant homodimeric bactenecin, a cathelicidin‐derived antimicrobial peptide
Authors: Lee Ju Y. , Yang Sung‐Tae , Lee Seung K. , Jung Hyun H. , Shin Song Y. , Hahm Kyung‐Soo , Kim Jae I.
Published: July 2008

The cathelicidin antimicrobial peptide bactenecin is a β‐hairpin molecule with a single disulfide bond and broad antimicrobial activity. The proform of bactenecin exists as a dimer, however, and it has been proposed that bactenecin is released as a dimer in vivo, although there has been little study of the dimeric form of bactenecin. To investigate the effect of bactenecin dimerization on its biological activity, we characterized the dimer’s effect on phospholipid membranes, the kinetics of its bactericidal activity, and its salt sensitivity. We initially synthesized two bactenecin dimers (antiparallel and parallel) and two monomers (β‐hairpin and linear). Under oxidative folding conditions, reduced linear bactenecin preferentially folded into a dimer forming a ladder‐like structure via intermolecular disulfide bonding. As compared to the monomer, the dimer had a greater ability to induce lysis of lipid bilayers and was more rapidly bactericidal. Interestingly, the dimer retained antimicrobial activity at physiological salt concentrations (150 mm NaCl), although the monomer was inactivated. This salt resistance was also seen with bactenecin dimer containing one intermolecular disulfide bond, and the bactenecin dimer appears to undergo multimeric oligomerization at high salt concentrations. Overall, dimeric bactenecin shows potent and rapid antimicrobial activity, and resists salt‐induced inactivation under physiological conditions through condensation and oligomerization. These characteristics shed light on the features that a peptide would need to serve as an effective therapeutic agent.
The product chain length determination mechanism of type II geranylgeranyl diphosphate synthase requires subunit interaction
Authors: Noike Motoyoshi , Katagiri Takashi , Nakayama Toru , Koyama Tanetoshi , Nishino Tokuzo , Hemmi Hisashi
Published: July 2008

The product chain length determination mechanism of type II geranylgeranyl diphosphate synthase from the bacterium, Pantoea ananatis, was studied. In most types of short‐chain (all‐E) prenyl diphosphate synthases, bulky amino acids at the fourth and/or fifth positions upstream from the first aspartate‐rich motif play a primary role in the product determination mechanism. However, type II geranylgeranyl diphosphate synthase lacks such bulky amino acids at these positions. The second position upstream from the G(Q/E) motif has recently been shown to participate in the mechaism of chain length determination in type III geranylgeranyl diphosphate synthase. Amino acid substitutions adjacent to the residues upstream from the first aspartate‐rich motif and from the G(Q/E) motif did not affect the chain length of the final product. Two amino acid insertion in the first aspartate‐rich motif, which is typically found in bacterial enzymes, is thought to be involved in the product determination mechanism. However, deletion mutation of the insertion had no effect on product chain length. Thus, based on the structures of homologous enzymes, a new line of mutants was constructed in which bulky amino acids in the α‐helix located at the expected subunit interface were replaced with alanine. Two mutants gave products with longer chain lengths, suggesting that type II geranylgeranyl diphosphate synthase utilizes an unexpected mechanism of chain length determination, which requires subunit interaction in the homooligomeric enzyme. This possibility is strongly supported by the recently determined crystal structure of plant type II geranylgeranyl diphosphate synthase.
Two CYP17 genes in the South African Angora goat (Capra hircus) – the identification of three genotypes that differ in copy number and steroidogenic output
Authors: Storbeck Karl‐Heinz , Swart Amanda C. , Snyman Margaretha A. , Swart Pieter
Published: July 2008

In mammals, cytochrome P450 17α‐hydroxylase/17–20 lyase (CYP17), which is encoded by a single gene, plays a critical role in the production of mineralocorticoids, glucocorticoids and androgens by the adrenal cortex. Two CYP17 isoforms with unique catalytic properties have been identified in the South African Angora goat (Capra hircus), a subspecies that is susceptible to cold stress because of the inability of the adrenal cortex to produce sufficient levels of cortisol. A real‐time‐based genotyping assay was used in this study to identify the distribution of the two CYP17 alleles in the South African Angora population. These data revealed that the two CYP17 isoforms were not the product of two alleles of the same gene, but two separate CYP17 genes encoding the two unique CYP17 isoforms. This novel finding was subsequently confirmed by quantitative real‐time PCR. Goats were divided into three unique genotypes which differed not only in the genes encoding CYP17, but also in copy number. Furthermore, in vivo assays revealed that the identified genotypes differed in their ability to produce cortisol in response to intravenous insulin injection. This study clearly demonstrates the presence of two CYP17 genes in the South African Angora goat, and further implicates CYP17 as the primary cause of the observed hypocortisolism in this subspecies.
New insights into the functions and N‐glycan structures of factor X activator from Russell’s viper venom
Authors: Chen Hong‐Sen , Chen Jin‐Mei , Lin Chia‐Wei , Khoo Kay‐Hooi , Tsai Inn‐Ho
Published: July 2008

The coagulation factor X activator from Russell’s viper venom (RVV‐X) is a heterotrimeric glycoprotein. In this study, its three subunits were cloned and sequenced from the venom gland cDNAs of Daboia siamensis. The deduced heavy chain sequence contained a C‐terminal extension with four additional residues to that published previously. Both light chains showed 77–81% identity to those of a homologous factor X activator from Vipera lebetina venom. Far‐western analyses revealed that RVV‐X could strongly bind protein S, in addition to factors X and IX. This might inactivate protein S and potentiate the disseminated intravascular coagulation syndrome elicited by Russell’s viper envenomation. The N‐glycans released from each subunit were profiled and sequenced by MALDI‐MS and MS/MS analyses of the permethyl derivatives. All the glycans, one on each light chain and four on the heavy chain, showed a heterogeneous pattern, with a combination of variable terminal fucosylation and sialylation on multiantennary complex‐type sugars. Amongst the notable features were the presence of terminal Lewis and sialyl‐Lewis epitopes, as confirmed by western blotting analyses. As these glyco‐epitopes have specific receptors in the vascular system, they possibly contribute to the rapid homing of RVV‐X to the vascular system, as supported by the observation that slower and fewer fibrinogen degradation products are released by desialylated RVV‐X than by native RVV‐X.
Binding of berberine to human telomeric quadruplex – spectroscopic, calorimetric and molecular modeling studies
Authors: Arora Amit , Balasubramanian Chandramouli , Kumar Niti , Agrawal Saurabh , Ojha Rajendra P. , Maiti Souvik
Published: July 2008

This study examines the characteristics of binding of berberine to the human telomeric d[AG3(T2AG3)3] quadruplex. By employing UV‐visible spectroscopy, fluorescence spectroscopy and isothermal titration calorimetry, we found that the binding affinity of berberine to the human telomeric quadruplex is 106. The complete thermodynamic profile for berberine binding to the quadruplex, at 25 °C, shows a small negative enthalpy (ΔH) of −1.7 kcal·mol−1, an entropy change with TΔS of +6.5 kcal·mol−1, and an overall favorable free energy (ΔG) of −8.2 kcal·mol−1 .Through the temperature dependence of ΔH, we obtained a heat capacity (ΔCp) of −94 (± 5) cal·mol−1·K−1. The osmotic stress method revealed that there is an uptake of 13 water molecules in the complex relative to the free reactants. Furthermore, the molecular modeling studies on different quadruplex–berberine complexes show that berberine stacking at the external G‐quartet is mainly aided by the π–π interaction and the stabilization of the high negative charge density of O6 of guanines by the positively charged N7 of berberine. The theoretical heat capacity (ΔCp) values for quadruplex–berberine models are −89 and −156 cal·mol−1·K−1.
Glutathione peroxidase family – an evolutionary overview
Authors: Margis Rogerio , Dunand Christophe , Teixeira Felipe K. , Margis‐Pinheiro Marcia
Published: July 2008

Glutathione peroxidases (EC 1.11.1.9 and EC 1.11.1.12) catalyze the reduction of H2O2 or organic hydroperoxides to water or corresponding alcohols using reduced glutathione. Some glutathione peroxidase isozymes have a selenium‐dependent glutathione peroxidase activity and present a selenocysteine encoded by the opal TGA codon. In the present study, insights into the evolution of the whole glutathione peroxidase gene family were obtained after a comprehensive phylogenetic analysis using the improved number of glutathione peroxidase sequences recorded in the PeroxiBase database (http://peroxidase.isb‐sib.ch/index.php). The identification of a common ancestral origin for the diverse glutathione peroxidase clusters was not possible. The complex relationships and evolutionary rates of this gene family suggest that basal glutathione peroxidase classes, present in all kingdoms, have originated from independent evolutionary events such as gene duplication, gene losses, lateral gene transfer among invertebrates and vertebrates or plants. In addition, the present study also emphasizes the possibility of some members being submitted to strong selective forces that probably dictated functional convergences of taxonomically distant groups.
Synchronous Ca2+ oscillation emerges from voltage fluctuations of Ca2+ stores
Authors: Yamashita Masayuki
Published: July 2008

Synchronous Ca2+ oscillation occurs in various cell types to regulate cellular functions. However, the mechanism for synchronization of Ca2+ increases between cells remains unclear. Recently, synchronous oscillatory changes in the membrane potential of internal Ca2+ stores were recorded using an organelle‐specific voltage‐sensitive dye [Yamashita et al. (2006) FEBS J273, 3585–3597], and an electrical coupling model of the synchronization of store potentials and Ca2+ releases has been proposed [Yamashita (2006) FEBS Lett580, 4979–4983]. This model is based on capacitative coupling, by which transient voltage changes can be synchronized, but oscillatory slow potentials cannot be communicated. Another candidate mechanism is synchronization of action potentials and ensuing Ca2+ influx through voltage‐dependent Ca channels. The present study addresses the question of whether Ca2+ increases are synchronized by action potentials, and how oscillatory store potentials are synchronized across the cells. Electrophysiological and Ca2+‐sensitive fluorescence measurements in early embryonic chick retina showed that synchronous Ca2+ oscillation was caused by releases of Ca2+ from Ca2+ stores without any evidence of action potentials in retinal neuroepithelial cells or newborn neurons. High‐speed fluorescence measurement of store membrane potential surprisingly revealed that the synchronous oscillatory changes in the store potential were periodic repeats of a burst of high‐frequency voltage fluctuations. The burst coincided with a Ca2+ increase. The present study suggests that synchronization of Ca2+ release is mediated by the high‐frequency fluctuation in the store potential. Close apposition of the store membrane and plasma membrane in an epithelial structure would allow capacitative coupling across the cells.
Biosynthesis of isoprenoids – studies on the mechanism of 2C‐methyl‐d‐erythritol‐4‐phosphate synthase
Authors: Lauw Susan , Illarionova Victoria , Bacher Adelbert , Rohdich Felix , Eisenreich Wolfgang
Published: July 2008

2C‐Methyl‐d‐erythritol‐4‐phosphate synthase, encoded by the ispC gene (also designated dxr), catalyzes the first committed step in the nonmevalonate isoprenoid biosynthetic pathway. The reaction involves the isomerization of 1‐deoxy‐d‐xylulose 5‐phosphate, giving a branched‐chain aldose derivative that is subsequently reduced to 2C‐methyl‐d‐erythritol 4‐phosphate. The isomerization step has been proposed to proceed as an intramolecular rearrangement or a retroaldol–aldol sequence. We report the preparation of 13C‐labeled substrate isotopologs that were designed to optimize the detection of an exchange of putative cleavage products that might occur in the hypothetical retroaldol–aldol reaction sequence. In reaction mixtures containing large amounts of 2C‐methyl‐d‐erythritol‐4‐phosphate synthase from Escherichia coli, Mycobacterium tuberculosis or Arabidopsis thaliana, and a mixture of [1‐13C1]‐2C‐methyl‐d‐erythritol 4‐phosphate and [3‐13C1]2C‐methyl‐d‐erythritol 4‐phosphate, the reversible reaction could be followed over thousands of reaction cycles. No fragment exchange could be detected by NMR spectroscopy, and the frequency of exchange, if any, is less than 5 p.p.m. per catalytic cycle. Hydroxyacetone, the putative second fragment expected from the retroaldol cleavage, was not incorporated into the enzyme product. In contrast to other reports, IspC did not catalyze the isomerisation of 1‐deoxy‐d‐xylulose 5‐phosphate to give 1‐deoxy‐l‐ribulose 5‐phosphate under any conditions tested. However, we could show that the isomerization reaction proceeds at room temperature without a requirement for enzyme catalysis. Although a retroaldol–aldol mechanism cannot be ruled out conclusively, the data show that a retroldol–aldol reaction sequence would have to proceed with very stringent fragment containment that would apply to the enzymes from three genetically distant organisms.
Microcin J25 induces the opening of the mitochondrial transition pore and cytochrome c release through superoxide generation
Authors: Niklison Chirou María , Bellomio Augusto , Dupuy Fernando , Arcuri Beatriz , Minahk Carlos , Morero Roberto
Published: July 2008

Microcin J25, an antimicrobial lasso‐structure peptide, induces the opening of mitochondrial permeability transition pores and the subsequent loss of cytochrome c. The microcin J25 effect is mediated by the stimulation of superoxide anion overproduction. An increased uptake of calcium is also involved in this process. Additional studies with superoxide dismutase, ascorbic acid and different specific inhibitors, such as ruthenium red, cyclosporin A and Mn2+, allowed us to establish a time sequence of events starting with the binding of microcin J25, followed by superoxide anion overproduction, opening of mitochondrial permeability transition pores, mitochondrial swelling and the concomitant leakage of cytochrome c.
EP4and EP2Receptor Subtypes Involved in Colonic Secretion in Rat
Authors: Mosa Ahmed Soliman , Hansen Mark Berner , Tilotta Cristina Maria , Bindslev Niels
Published: July 2008

Abstract: The study was designed to determine the prostaglandin EP receptor subtypes functionally involved in electrogenic ion secretion in rat colon. With 30 rats, measurements of short circuit current (SCC) and slope conductance were obtained by Ussing chamber technique. Prostaglandin E2 (PGE2) and other EP receptor selective agonists were employed on stripped rat colon pre‐treated with indomethacin and theophylline. Receptor‐specific agonists were butaprost (EP2), sulprostone (EP1and EP3) and PGE1alcohol (OH‐PGE1) (EP4). GW627368X was used as a specific EP4receptor antagonist. Forskolin‐induced SCC was used as a control of tissue viability. The mean basal SCC was 24.5 ± 0.9 µA/cm2(range 9.8–45.1), and mean basal slope conductance was 23.7 ± 6.1 mS/cm2(range 9.7–39.8). The basal SCC decreased after pre‐treatment with indomethacin and increased after pre‐treatment with theophylline. PGE2, butaprost and OH‐PGE1stimulated maximal increase in SCC (55.8 ± 4.1, 43.9 ± 3.8 and 93.9 ± 2.7 µA/cm2, respectively), while sulprostone had no apparent effects. GW627368X eliminated OH‐PGE1‐induced SCC and partially PGE2‐induced SCC, leaving butaprost‐induced SCC almost unperturbed. Bumetanide, 20 µM, inhibited between 40% and 80% of the agonist‐induced changes in SCC. In conclusion, compilation of the results on induced SCC by subtype specific receptor agonists for EP receptors and the pattern of induced SCCs inhibited by GW627368X indicate the EP4receptor subtype as the major mediator of PGE2‐induced electrogenic ion secretion with a lesser induction through the EP2receptor subtype.
Control of Nepheline Crystallization in Nuclear Waste Glass
Authors: Fox Kevin M. , Edwards Thomas B. , Peeler David K.
Published: July 2008

Glass frits with high B2O3 concentrations, when combined with high‐alumina concentration nuclear waste, will form glasses with durabilities that are acceptable for disposal (normalized boron release of <1.7 g/L) and predictable using a free energy of hydration model. Glasses with nepheline discriminator values closest to 0.62 showed significant differences in durability between the quenched and heat‐treated versions. Nepheline crystallized in the glass with the lowest nepheline discriminator value. The high‐B2O3 frit was successful in producing glasses without crystallization at waste loadings of up to 45 wt%. The melt rate of this frit was also considerably improved (13.1 g/min).
Frequency Effects on Fatigue Behavior of a Silicon Carbide Fiber‐Reinforced Glass–Ceramic Composite (SiC/MAS)
Authors: Ahn Joon‐Mo , Mall Shankar , Ahn Joon‐Mo
Published: July 2008

The effects of cyclic frequency on the fatigue behavior of silicon carbide (Nicalon) fiber‐reinforced glass–ceramic matrix (SiC/magnesium aluminosilicate (MAS)) were investigated. Tension–tension fatigue tests were conducted at two frequencies, 10 and 900 Hz, to establish stress versus cycles to failure (S–N) relationships. Cycles to failure at a given stress level decreased with an increase of the applied frequency. Analysis of damage mechanisms suggests that there was an enhancement of fiber/matrix interfacial bonding at the higher frequency due to the formation of SiO2 from the reaction of oxygen species of the matrix with SiC of the fiber.
Monodisperse Calcium Carbonate Microtablets Forming at 70°C in Prerefrigerated CaCl2–Gelatin–Urea Solutions
Authors: Tas A. Cuneyt
Published: July 2008

Calcium carbonate particles with a unique tablet shape were produced by simply aging the prerefrigerated (at 4°C for 24 h) CaCl2–gelatin–urea solutions at 70°C for 24 h in ordinary glass media bottles. Gelatin is known to be the denatured collagen. The thermal decomposition of dissolved urea was exploited to provide the Ca2+ion and gelatin‐containing solutions with aqueous carbonate ions. Monodisperse CaCO3microtablets formed in solution had a mean particle size of 4±2.5 μm. CaCO3microtablets were biphasic in nature and comprised of about 93% vaterite and 7% calcite. Identical solutions used without prerefrigeration yielded only trigonal prismatic calcite crystals upon aging at 70°C for 24 h. Prerefrigeration of CaCl2–gelatin–urea solutions was thus shown to have a remarkable effect on the particle morphology. Samples were characterized by scanning electron microscopy, Fourier‐transform infrared spectroscopy, and powder X‐ray diffraction.
Fabrication and Performance of Cone‐Shaped Segmented‐In‐Series Solid Oxide Fuel Cells
Authors: Zhang Yaohui , Liu Jiang , Yin Juan , Yuan Wensheng , Sui Jing
Published: July 2008

A new design of segmented‐in‐series solid oxide fuel cells (SOFCs) is presented in this paper. The small cone‐shaped anode tubes were fabricated by slip casting and the yttria‐stabilized zirconia (YSZ) electrolyte membranes were deposited onto the anode tubes by dip coating. After sintering at 1400°C for 4 h, a dense and crack‐free YSZ membrane with a thickness of 20 μm was successfully obtained. The single cell, using moist hydrogen as a fuel and ambient air as an oxidant, provides maximum power densities of 1.15, 0.8, 0.47, 0.26, 0.14, and 0.07 W/cm2 at 850°C, 800°C, 750°C, 700°C, 650°C, and 600°C, respectively.
Influence of Synthesis Conditions on the Characteristics of Biphasic Calcium Phosphate Powders
Authors: Marchi Juliana , Greil Peter , Bressiani José Carlos , Bressiani Ana , Müller Frank
Published: July 2008

Mixtures of hydroxyapatite (HAp) and tricalcium phosphate (TCP) powders with different Ca/P ratios were prepared by a wet chemical precipitation synthesis of calcium‐deficient hydroxy apatite (CDHA) and subsequent calcination. The influence of precipitation method and calcination temperature on the chemical and physical properties of the resulting powders were evaluated. Different ratios between HAp and TCP were obtained by variation of the velocity of orthophosphoric acid addition into calcium hydroxide suspension. Slow addition (1 mL/min, S‐powder) of H3PO4 into Ca(OH)2 suspension lead to a higher amount of CO3 groups substituting PO4 in the apatite lattice compared to powders synthesized by fast addition (200 mL/min, F‐powder). Consequently, the Ca/P molar ratio of S‐powder (1.55) was higher than that of F‐powder (1.52), leading to a higher amount of HAp in the resulting calcinated powders. Both powders show significant differences in their calcinations behavior. Whereas for F‐powders a temperature of 750°C was adequate for a complete transformation of CDHA to TCP and HAp, 950°C were required for S‐powders.
Hydroxide‐Bonding Strength Measurements for Space‐Based Optical Missions
Authors: Preston Alix , Balaban Benjamin , Mueller Guido
Published: July 2008

Optical contacting has long been used in interferometric experiments both on the ground and in space‐based missions. Its optical clarity makes it an ideal method to joint materials of comparable coefficients of thermal expansion. Once the two pieces are bonded, they are commonly broken through thermal or vibrational cycling. Unfortunately, larger bond areas are needed for the bond to form appreciable strength, which often excludes it from being used in complex optical bench designs in space‐based missions. Another method, known colloquially as hydroxide bonding, has shown to have superior strength to optical contacting using smaller bonding areas. In addition, the hydroxide bonding process will work on several materials that do not need to meet the stringent polishing requirements of optical contacting. These properties make hydroxide bonding suitable for complex optical bench designs that can withstand the large accelerations encountered during launch conditions for use in space‐based missions. In this paper, we report on shear strength measurements of BK7‐to‐BK7 hydroxide bonds as well as present new results for BK7‐to‐silicon carbide and BK7‐to‐Super Invar bonds.
Multifunctional Properties of Alumina Composites Reinforced by a Hybrid Filler
Authors: Ahmad Kaleem , Pan Wei , Qu Zhixue
Published: July 2008

Hybrid microstructure design has been used to fabricate alumina composites reinforced by 5 vol% of multiwalled carbon nanotube (MWNT) together with different (1, 2, 3 vol%) contents of SiC nanoparticles by spark plasma sintering. The mechanical, thermal, and electrical properties of the composites were determined as a function of the SiC volume fraction. The thermal conductivity decreased for 1 and 2 vol% of SiC, while for 3 vol%, it increased. Substantial improvements in the fracture toughness, bending strength, and electrical conductivity were observed and attributed to a synergetic effect of the MWNT and SiC nanoparticles in the hybrid microstructure design.
EXPERIMENTALLY FERMENTED SAUSAGE FROM GOOSE MEAT AND QUALITY ATTRIBUTES
Authors: GULBAZ G. , KAMBER U.
Published: July 2008

This research studies various attributes of an experimental fermented goose meat sausage with a view to contributing one more flavor to the product range of the meat industry. In the study, experimental fermented sausages were made from goose meat. Samples were taken from the sausages during the 21‐day maturation period in order to determine changes in the product microflora. Microbiologic analyses were conducted and it was found that the total aerobic mesophyl bacteria count in the samples was between 5.0 × 104 cfu/g and 4.0 × 108 cfu/g, the lactobacilli count between 4.7 × 103 cfu/g and 2.8 × 108 cfu/g, the staphylococ‐micrococcus count between 2.6 × 103 cfu/g and 1.6 × 106 cfu/g and the mold–yeast count between 1.4 × 103 cfu/g and 2.6 × 105 cfu/g. In chemical analyses conducted at the end of the maturation period, the sausages were found to contain 37.2% moisture, 15.8% fat, 27.5% protein, 4.1% ash and to have a pH of 5.2 LA. In a sensorial analysis conducted by a 10‐member group of panelists using a 5‐point scale, the fermented sausages made from goose meat were compared with fermented sausages made from raw and cooked beef. The results of the microbiologic, chemical and sensorial analyses conducted on the goose meat sausages were found to be in harmony with the values for maturated beef sausage, leading to the conclusion that goose meat may be used in fermented sausage technology.

PRACTICAL APPLICATIONS

The aims of the present study are to produce new meat formulations for a gradually increasing world population and to promote development of goose breeding. Studies on the presentation of new food products prepared by various food sources offer an effective use of animal protein sources and an increased portion of animal products in economic portions. Moreover, introduction of this type of new meat product extends product varieties and orients consumers toward different alternatives.
OCCURRENCE OF ESCHERICHIA COLIO157:H7/O157, LISTERIA MONOCYTOGENES AND SALMONELLA SPP. IN BEEF SLAUGHTERHOUSE ENVIRONMENTS, EQUIPMENT AND WORKERS
Authors: AKKAYA L. , ALISARLI M. , CETINKAYA Z. , KARA R. , TELLI R.
Published: July 2008

Escherichia coli O157/O157:H7, Listeria monocytogenes and Salmonella spp. are major foodborne pathogens and the emergence of these pathogens has been reported in many countries. The aim of this study was to investigate contamination of the beef slaughterhouse environment, equipment and workers with E. coli O157/O157:H7, L. monocytogenes and Salmonella spp. For this study, 500 swab samples were taken from 19 different points in five privately owned slaughterhouses, their periphery, slaughterhouse equipment and slaughterhouse employees. The presence of E. coli O157:H7/O157, L. monocytogenes and Salmonella spp. was determined with the application of the immunomagnetic separation method. Our study showed that the swabs taken from the five slaughterhouses contained E. coli O157:H7 in the environment, equipment, abattoir workers and water with a frequency 0.31, 1, 1.42 and 0%, respectively; while E. coli O157 was evident in the environment, equipment, abattoir workers and water with a ratio of 15, 10, 10 and 0%, respectively; L. monocytogenes was detected in the environment, equipment, abattoir workers and water at a ratio of 4.37, 15, 5.71 and 0%, respectively; and Salmonella spp. occurrence in the environment, equipment, abattoir workers and water at a ratio of 3.43, 16, 11.42, and 0%, respectively. Implementing hazard analysis critical control point principles in work procedures would definitely reduce the gross contamination occurring in abattoirs.

PRACTICAL APPLICATIONS

This study has revealed the effect of personnel and equipment on the contamination routes of E. coli O157:H7, Listeria monocytogenes and Salmonella spp. in meat in slaughterhouses and showed that especially L. monocytogenes and Salmonella spp. may pose a higher risk than E. coli O157:H7 in slaughterhouses.