bluuebunny/crossref_metadata_2025 huggingface dataset:
TRAF1 polymorphisms associated with rheumatoid arthritis susceptibility in Asians and in Caucasians
Authors: Han Tae‐Un , Bang So‐Young , Kang Changwon , Bae Sang‐Cheol
Published: August 2009

Objective

Recent genome‐wide association scans and replication studies of European populations have disclosed several single‐nucleotide polymorphisms (SNPs) associated with rheumatoid arthritis (RA) susceptibility. The aim of this study was to evaluate the RA‐associated loci by genotyping previously reported SNPs and additional tag SNPs in a Korean population.

Methods

A total of 1,316 unrelated RA patients and 1,006 controls were genotyped for 12 SNPs identified in genome‐wide scans and for 12 additional tag SNPs in IL2RB, OLIG3–TNFAIP3, PTPN22, and TRAF1–C5, and the findings were statistically compared.

Results

None of the SNPs tested was associated with RA susceptibility, except rs7021206 in TRAF1 intron 3 (P = 0.0032) and, among the SNPs previously reported, rs6457617 in HLA (P = 4.6 × 10−35). The association of rs7021206 was positive in patients who were seropositive for rheumatoid factor (P = 0.0051) or for anti–cyclic citrullinated peptide autoantibodies (P = 0.0062). However, Korean patients were negative for the association of rs3761847 in the TRAF1–C5 intergenic region previously reported in Caucasians. Linkage disequilibrium between rs3761847 and rs7021206 was not as high in Koreans (r2 = 0.37) as in Caucasians (r2 = 0.67), which explains the lack of association of rs3761847 in Koreans. Accordingly, RA susceptibility was localized to an extended haplotype marked by rs7021206 rather than rs3761847, and SNPs highly correlated with rs7021206 (r2 ≥ 0.81) extended from rs1953126 in the PHF19–TRAF1 intergenic region to rs2900180 in the TRAF1–C5 intergenic region, spanning 66 kb.

Conclusion

Our results demonstrate that within and around TRAF1, excluding PHF19 and C5, SNPs highly correlated with rs7021206, but not those correlated with rs3761847, are associated with RA in both Asians and Caucasians and are possibly correlated with causative variations.
Regression of systemic lupus erythematosus after development of an acquired Toll‐like receptor signaling defect and antibody deficiency
Authors: Visentini Marcella , Conti Valentina , Cagliuso Maria , Tinti Francesca , Siciliano Giulia , Trombetta Amelia C. , Mitterhofer Anna Paola , Fiorilli Massimo , Quinti Isabella
Published: August 2009

Toll‐like receptor 9 (TLR‐9) and TLR‐7 may have a role in the production of anti‐DNA and anti‐RNA autoantibodies, respectively, but murine models do not clearly demonstrate their contribution to the development of systemic lupus erythematosus (SLE). Herein we describe a patient with SLE who had long‐lasting remission of her autoimmune disease after development of an antibody deficiency resembling common variable immunodeficiency (CVID). After CVID had developed, anti–double‐stranded DNA antibodies disappeared, although antinuclear antibodies remained positive for >10 years. In vitro studies revealed that the patient's B cells proliferated poorly and failed to differentiate into plasmablasts after stimulation of either TLR‐9 or TLR‐7, providing evidence for an acquired defect of the signaling pathway downstream of these TLRs. These observations suggest, although indirectly, that signaling through TLR‐9 and TLR‐7 is important in the pathogenesis of human SLE, and indicate that investigation of potential treatment strategies with TLR antagonists is warranted.
Induction of apoptosis in the synovium of mice with autoantibody‐mediated arthritis by the intraarticular injection of double‐stranded MicroRNA‐15a
Authors: Nagata Yoshihiko , Nakasa Tomoyuki , Mochizuki Yu , Ishikawa Masakazu , Miyaki Shigeru , Shibuya Hayatoshi , Yamasaki Keiichiro , Adachi Nobuo , Asahara Hiroshi , Ochi Mitsuo
Published: August 2009

Objective

MicroRNA is a family of noncoding RNAs that exhibit tissue‐specific or developmental stage–specific expression patterns and are associated with human diseases. MicroRNA‐15a (miR‐15a) is reported to induce cell apoptosis by negatively regulating the expression of Bcl‐2, which suppresses the apoptotic processes. The purpose of this study was to investigate whether double‐stranded miR‐15a administered by intraarticular injection could be taken up by cells and could induce Bcl‐2 dysfunction and cell apoptosis in the synovium of arthritic mice in vivo.

Methods

Autoantibody‐mediated arthritis was induced in male DBA/1J mice. In the experimental group, double‐stranded miR‐15a labeled with FAM–atelocollagen complex was injected into the knee joint. In the control group, control small interfering RNA–atelocollagen complex was injected into the knee joint. Synovial expression of miR‐15a was analyzed by quantitative polymerase chain reaction, FAM by fluorescence microscopy, Bcl‐2 by Western blotting, and Bcl‐2 and caspase 3 by immunohistochemistry.

Results

The expression of miR‐15a in the synovium of the experimental group was significantly higher than that in the control group. Green fluorescence emission of FAM was observed in the synovium of the experimental group. Bcl‐2 protein was down‐regulated and the expression of caspase 3 was increased as compared with that in the control group.

Conclusion

These results indicate that the induction of cell apoptosis after intraarticular injection of double‐stranded miR‐15a occurs through inhibition of the translation of Bcl‐2 protein in arthritic synovium.
HLA–B27 misfolding and the unfolded protein response augment interleukin‐23 production and are associated with Th17 activation in transgenic rats
Authors: DeLay Monica L. , Turner Matthew J. , Klenk Erin I. , Smith Judith A. , Sowders Dawn P. , Colbert Robert A.
Published: August 2009

Objective

To determine whether HLA–B27 misfolding and the unfolded protein response (UPR) result in cytokine dysregulation and whether this is associated with Th1 and/or Th17 activation in HLA–B27/human β2‐microglobulin (Huβ2m)–transgenic rats, an animal model of spondylarthritis.

Methods

Cytokine expression in lipopolysaccharide (LPS)–stimulated macrophages was analyzed in the presence and absence of a UPR induced by chemical agents or by HLA–B27 up‐regulation. Cytokine expression in colon tissue and in cells purified from the lamina propria was determined by real‐time reverse transcription–polymerase chain reaction analysis, and differences in Th1 and Th17 CD4+ T cell populations were quantified after intracellular cytokine staining.

Results

Interleukin‐23 (IL‐23) was found to be synergistically up‐regulated by LPS in macrophages undergoing a UPR induced by pharmacologic agents or by HLA–B27 misfolding. IL‐23 was also increased in the colon tissue from B27/Huβ2m‐transgenic rats concurrently with the development of intestinal inflammation, and IL‐17, a downstream target of IL‐23, exhibited robust up‐regulation in a similar temporal pattern. IL‐23 and IL‐17 transcripts were localized to CD11+ antigen‐presenting cells and CD4+ T cells, respectively, from the colonic lamina propria. Colitis was associated with a 6‐fold expansion of CD4+ IL‐17–expressing T cells.

Conclusion

The IL‐23/IL‐17 axis is strongly activated in the colon of B27/Huβ2m‐transgenic rats with spondylarthritis‐like disease. HLA–B27 misfolding and UPR activation in macrophages can result in enhanced induction of the pro‐Th17 cytokine IL‐23. These results suggest a possible link between HLA–B27 misfolding and immune dysregulation in this animal model, with implications for human disease.
Inhibition of lymphangiogenesis and lymphatic drainage via vascular endothelial growth factor receptor 3 blockade increases the severity of inflammation in a mouse model of chronic inflammatory arthritis
Authors: Guo Ruolin , Zhou Quan , Proulx Steven T. , Wood Ronald , Ji Rui‐Cheng , Ritchlin Christopher T. , Pytowski Bronislaw , Zhu Zhenping , Wang Yong‐Jun , Schwarz Edward M. , Xing Lianping
Published: August 2009

Objective

This study was undertaken to investigate the effect of lymphatic inhibition on joint and draining lymph node (LN) pathology during the course of arthritis progression in mice.

Methods

Tumor necrosis factor (TNF)–transgenic mice were used as a model of chronic inflammatory arthritis. Mice were subjected to contrast‐enhanced magnetic resonance imaging to obtain ankle and knee joint synovial volumes and draining popliteal LN volumes before and after 8 weeks of treatment with vascular endothelial growth factor receptor 3 (VEGFR‐3) neutralizing antibody, VEGFR‐2 neutralizing antibody, or isotype IgG. Animals were subjected to near‐infrared lymphatic imaging to determine the effect of VEGFR‐3 neutralization on lymph transport from paws to draining popliteal LNs. Histologic, immunohistochemical, and reverse transcriptase–polymerase chain reaction analyses were used to examine lymphatic vessel formation and the morphology of joints and popliteal LNs.

Results

Compared with IgG treatment, VEGFR‐3 neutralizing antibody treatment significantly decreased the size of popliteal LNs, the number of lymphatic vessels in joints and popliteal LNs, lymphatic drainage from paws to popliteal LNs, and the number of VEGF‐C–expressing CD11b+ myeloid cells in popliteal LNs. However, it increased the synovial volume and area of inflammation in ankle and knee joints. VEGFR‐2 neutralizing antibody, in contrast, inhibited both lymphangiogenesis and joint inflammation.

Conclusion

These findings indicate that lymphangiogenesis and lymphatic drainage are reciprocally related to the severity of joint lesions during the development of chronic arthritis. Lymphatic drainage plays a beneficial role in controlling the progression of chronic inflammation.
Type II collagen levels correlate with mineralization by articular cartilage vesicles
Authors: Jubeck Brian , Muth Emily , Gohr Claudia M. , Rosenthal Ann K.
Published: August 2009

Objective

Pathologic mineralization is common in osteoarthritic (OA) cartilage and may be mediated by extracellular organelles known as articular cartilage vesicles (ACVs). Paradoxically, ACVs isolated from OA human cartilage mineralize poorly in vitro compared with those isolated from normal porcine cartilage. We recently showed that collagens regulate ACV mineralization. We sought to determine differences between collagens and collagen receptors on human and porcine ACVs as a potential explanation of their different mineralization behaviors.

Methods

ACVs were enzymatically released from old and young human and porcine hyaline articular cartilage. Western blotting was used to determine the presence of types I, II, VI, and X collagen and various collagen receptors on ACVs. Type II collagen was quantified by enzyme‐linked immunosorbent assay. Biomineralization was assessed by measuring the uptake of 45Ca by isolated ACVs in agarose gels and by ACVs in situ in freeze‐thawed cartilage.

Results

As previously shown, isolated human ACVs mineralized poorly in response to ATP compared with porcine ACVs, but human and porcine ACVs mineralized similarly in situ in freeze‐thawed cartilage. Type II collagen levels were 100‐fold higher in isolated human ACVs than in porcine ACVs. Type II collagen in human ACVs was of high molecular weight. Transglutaminase‐crosslinked type II collagen showed increased resistance to collagenase, suggesting a possible explanation for residual collagen on human ACVs. Expression of other collagens and collagen receptors was similar on human and porcine ACVs.

Conclusion

Higher levels of type II collagen in human ACV preparations, perhaps mediated by increased transglutaminase crosslinking, may contribute to the decreased mineralization observed in isolated human ACVs in vitro.
Outside‐to‐inside signaling through transmembrane tumor necrosis factor reverses pathologic interleukin‐1β production and deficient apoptosis of rheumatoid arthritis monocytes
Authors: Meusch Undine , Rossol Manuela , Baerwald Christoph , Hauschildt Sunna , Wagner Ulf
Published: August 2009

Objective

Monocytes are a major source of proinflammatory cytokines in rheumatoid arthritis (RA), and inhibitors of monocytic cytokines are highly efficient agents for treatment of the disease. The aim of this study was to analyze the effects of a therapeutic anti–tumor necrosis factor α (anti‐TNFα) antibody on monocytes from patients with RA and healthy control subjects.

Methods

Peripheral blood monocytes from patients with RA and healthy control subjects were incubated in the presence of anti‐TNFα antibody or IgG. Annexin V staining, caspase activation, poly(ADP‐ribose) polymerase cleavage, and DNA staining with propidium iodide were used to analyze apoptosis. The signaling events elicited in monocytes by infliximab were analyzed by Western blotting and electromobility shift assay.

Results

Peripheral blood monocytes from patients with RA were characterized by increased expression of transmembrane TNFα, spontaneous in vitro production of interleukin‐1β (IL‐1β), and a decreased rate of spontaneous ex vivo apoptosis. Incubation with infliximab induced significantly increased apoptosis in monocytes from patients with RA but not in monocytes from healthy control subjects. This apoptosis was triggered by reverse signaling of transmembrane TNF after ligation by infliximab and was independent of caspase activation. Instead, transmembrane TNF reverse signaling inhibited the constitutive NF‐κB activation in RA monocytes, suppressed IL‐1β secretion, and normalized spontaneous in vitro apoptosis. This normalization was reversible by the addition of exogenous IL‐1β.

Conclusion

This study demonstrates that outside‐to‐inside signaling through transmembrane TNF after ligation by infliximab inhibits constitutive NF‐κB activation and suppresses spontaneous IL‐1β production by monocytes from patients with RA. Besides the induction of monocyte apoptosis, this inhibition could also contribute to the therapeutic effects observed during treatment with TNFα inhibitors.
Magnetic resonance imaging‐based cartilage loss in painful contralateral knees with and without radiographic joint space narrowing: Data from the osteoarthritis initiative
Authors: Eckstein Felix , Benichou Olivier , Wirth Wolfgang , Nelson David R. , Maschek Susanne , Hudelmaier Martin , Kwoh C. Kent , Guermazi Ali , Hunter David
Published: August 2009

Objective

To determine by magnetic resonance imaging (MRI), whether knees with advanced radiographic disease (medial joint space narrowing [mJSN]) encounter greater longitudinal cartilage loss than contralateral knees with earlier disease (no or less mJSN).

Methods

Participants were selected from 2,678 cases in the Osteoarthritis Initiative, based on exhibition of bilateral pain, body mass index >25 (kg/m2), mJSN in 1 knee, no or less mJSN in the contralateral knee, and no lateral JSN in both knees. Eighty participants (mean ± SD age 60.6 ± 9.1 years) fulfilled these criteria. Medial tibial and femoral cartilage morphology was analyzed from the baseline and the 1‐year followup MRI (sagittal double echo at steady state by 3.0T) of both knees by experienced readers blinded to the time point and mJSN status.

Results

Knees with more radiographic mJSN displayed greater medial cartilage loss (−80 μm) assessed by MRI than contralateral knees with less mJSN (−57 μm). The difference reached statistical significance in participants with an mJSN grade of 2 or 3 (P = 0.005–0.08), but not in participants with an mJSN grade of 1 (P = 0.28–0.98). In knees with more mJSN, cartilage loss increased with higher grades of mJSN (P = 0.003 in the medial femur). Knees with an mJSN grade of 2 or 3 displayed greater cartilage loss in the weight‐bearing medial femur than in the posterior femur or in the medial tibia (P = 0.048).

Conclusion

Knees with advanced mJSN displayed greater cartilage loss than contralateral knees with less mJSN. These data suggest that radiography can be used to stratify fast structural progressors, and that MRI cartilage thickness loss is more pronounced at advanced radiographic disease stage.
Aggregating conclusive and inconclusive information: Data and a model based on the assessment of threat
Authors: Baranski Joseph V. , Petrusic William M.
Published: August 2009

This study examined the process of combining conclusive and inconclusive information using a Naval threat assessment simulation. On each of 36 trials, participants interrogated 10 pieces of information (e.g., speed, direction, bearing, etc.) about “targets” in a simulated radar space. The number of hostile, peaceful, and inconclusive cues was factorially varied across targets. Three models were developed to understand how inconclusive information is used in the judgment of threat. According to one model, inconclusive information is ignored and the judgment of threat is based only on the conclusive information. According to a second model, the amount of dominant conclusive information is normalized by all of the available information. Finally, according to a third model, inconclusive information is partitioned under the assumption that it equally represents both dominant and non‐dominant evidence. In Experiment 1, the data of novices (i.e., civilians) were best described by a model that assumes a partitioning of inconclusive evidence. This result was replicated in a second experiment involving variation of the global threat context. In a third experiment involving experts (i.e., Canadian Navy officers), the data of half of the participants were best described by the partitioning model and the data of the other half were best described by the normalizing model. In Experiments 1 and 2, the presence of inconclusive information produced a “dilution effect”, whereby hostile (peaceful) targets were judged as less hostile (peaceful) than the predictions of the Partitioning model. The dilution effect was not evident in the judgments of the Navy officers. Copyright © 2009 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Early development of the primordial mammalian diaphragm and cellular mechanisms of nitrofen‐induced congenital diaphragmatic hernia
Authors: Clugston Robin D. , Zhang Wei , Greer John J.
Published: August 2009

Congenital diaphragmatic hernia (CDH) is a frequently occurring cause of neonatal respiratory distress and is associated with high mortality and long‐term morbidity. Evidence from animal models suggests that CDH has its origins in the malformation of the pleuroperitoneal fold (PPF), a key structure in embryonic diaphragm formation. The aims of this study were to characterize the embryogenesis of the PPF in rats and humans, and to determine the potential mechanism that leads to abnormal PPF development in the nitrofen model of CDH. Analysis of rat embryos, and archived human embryo sections, allowed the timeframe of PPF formation to be determined for both species, thus delineating a critical period of diaphragm development in relation to CDH. Experiments on nitrofen‐exposed NIH 3T3 cells in vitro led us to hypothesize that nitrofen might cause diaphragmatic hernia in vivo by two possible mechanisms: through decreased cell proliferation or by inducing apoptosis. Data from nitrofen‐exposed rat embryos indicates that the primary mechanism of nitrofen teratogenesis in the PPF is through decreased cell proliferation. This study provides novel insight into the embryogenesis of the PPF in rats and humans, and it indicates that impaired cell proliferation might contribute to abnormal diaphragm development in the nitrofen model of CDH. Birth Defects Research (Part A) 2010. © 2009 Wiley‐Liss, Inc.
Maternal obesity and morbid obesity: The risk for birth defects in the offspring
Authors: Blomberg Marie I. , Källén Bengt
Published: August 2009

BACKGROUND: The objective of this study was to assess, in a large data set from Swedish Medical Health Registries, whether maternal obesity and maternal morbid obesity were associated with an increased risk for various structural birth defects. METHODS: The study population consisted of 1,049,582 infants born in Sweden from January 1, 1995, through December 31, 2007, with known maternal weight and height data. Women were grouped in six categories of body mass index (BMI) according to World Health Organization classification. Infants with congenital birth defects were identified from three sources: the Swedish Medical Birth Registry, the Register of Birth Defects, and the National Patient Register. Maternal age, parity, smoking, and year of birth were thought to be potential confounders and were included as covariates in the adjusted odds ratio analyses. RESULTS: Ten percent of the study population was obese. Morbid obesity (BMI ≥ 40) occurred in 0.7%. The prevalence of congenital malformations was 4.7%, and the prevalence of relatively severe malformations was 3.2%. Maternal prepregnancy morbid obesity was associated with neural tube defects OR 4.08 (95% CI 1.87–7.75), cardiac defects OR 1.49 (95% CI 1.24–1.80), and orofacial clefts OR 1.90 (95% CI 1.27–2.86). Maternal obesity (BMI ≥ 30) significantly increased the risk of hydrocephaly, anal atresia, hypospadias, cystic kidney, pes equinovarus, omphalocele, and diaphragmatic hernia. CONCLUSION: The risk for a morbidly obese pregnant woman to have an infant with a congenital birth defect is small, but for society the association is important in the light of the ongoing obesity epidemic. Birth Defects Research (Part A), 2010. © 2009 Wiley‐Liss, Inc.
Exposure of non‐target tissues in medical diathermy
Authors: Leitgeb N. , Omerspahic A. , Niedermayr F.
Published: August 2009

With different prevalence in different regions, radio frequency (RF) electromagnetic fields (EMF) are widely used for therapeutic tissue heating. Although short‐wave diathermy (27.12 MHz) is the most popular treatment modality, quantitative data on patient's exposure have been lacking. By numerical simulation with the numerical anatomical model NORMAN, intracorporal distributions of specific absorption rates (SAR) were investigated for different treatment scenarios and applicators. Quantitative data are provided for exposures of target treatment areas as well as for vulnerable regions such as the eye lenses, central nervous system, and testes. Different applicators and distances were investigated. Capacitive and inductive applicators exhibit quite a different heating efficiency. It could be shown that for the same output power therapeutic heat deposition can vary by almost one order of magnitude. By mimicking therapist's practice to use patient's heat perception as an indicator for output power setting, numerical data were elaborated demonstrating that muscle tissue exposures may be several times higher for inductive than for capacitive applicators. Presented quantitative data serve as a guide for power adjustment preventing relevant overexposures without compromising therapy; they also provide a basis for estimating target tissue heat load and developing therapeutic guidelines. Bioelectromagnetics 31:12–19, 2010. © 2009 Wiley‐Liss, Inc.
Resonance scattering spectral detection of ultratrace Hg(II) using herring sperm DNA modified nanogold probe as catalyst
Authors: Wen Guiqing , Liang Aihui , Jiang Zhiliang , Liao Xianjiu , Li Jianfu , Jiang Hesheng
Published: August 2009

Herring sperm DNA (hsDNA) was used to modify 10 nm nanogold to obtain a resonance scattering (RS) probe (AuhsDNA) for detection of Hg2+. In the presence of salt, Hg2+ interacts with AuhsDNA to form stable Hg2+–hsDNA complexes, and releases nanogold particles to form larger nanogold clusters that can be removed by membrane filtration. The excess AuhsDNA in the filtrate solution exhibits a catalytic effect on the reaction between hydroxylamine (NH2OH) and Cu(II). The excess AuhsDNA decreased with the addition of Hg2+, which led the RS intensity at 602 nm to decrease. The decreased RS intensity (Δl602 nm) had a linear response to Hg2+ concentration in the range of 0.4–400 nM, with a detection limit of 0.2 nM Hg2+. This RS method was applied for the detection of Hg2+ in water samples, with sensitivity, selectivity and simplicity. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis, characterization and fluorescent properties of cerium(III) glutathione complex
Authors: Han Guo‐Cheng , Liu You‐Nian
Published: August 2009

The cerium (III) glutathione complex was synthesized by the redox reaction of cerium (IV) with glutathione reduced (GSH) in aqueous solution. The Job‐plots indicate an ML (L = GSSG) stoichiometry of the complex. The fluorescent properties of the compound were investigated. The as‐prepared complex showed the characteristic maximum emission spectra of Ce(III) at 350 nm (λex = 255 nm). The fluorescence results show that the Ce(IV) ions are first reduced to Ce(III), and then form Ce(III) complex after reacting with GSH. The complex was characterized by element analysis and FT‐IR spectra; the stability of the complex was analyzed by cyclic voltammeters and DSC‐TG as well. Finally, Ce(IV) was successfully employed to determine the concentrations of GSH in the presence of GSSG, in which the fluorescence intensities are proportional to the concentrations of GSH in the range of 1–100 nM with the detection limit of 0.05 nM of GSH, without interference from the presence of GSSG. Copyright © 2009 John Wiley & Sons, Ltd.
Conformational stability of the full‐atom hexameric model of the ClpB chaperone from Escherichia coli
Authors: Ziętkiewicz Szymon , Ślusarz Magdalena J. , Ślusarz Rafał , Liberek Krzysztof , Rodziewicz‐Motowidło Sylwia
Published: August 2009

The Escherichia coli heat shock protein ClpB, a member of the Hsp100 family, plays a crucial role in cellular thermotolerance. In co‐operation with the Hsp70 chaperone system, it is able to solubilize proteins aggregated by heat shock conditions and refold them into the native state in an ATP‐dependent way. It was established that the mechanism of ClpB action depends on the formation of a ring‐shaped hexameric structure and the translocation of a protein substrate through an axial channel. The structural aspects of this process are not fully known. By means of homology modeling and protein–protein docking, we obtained a model of the hexameric arrangement of the full‐length ClpB protein complexed with ATP. A molecular dynamics simulation of this model was performed to assess its flexibility and conformational stability. The high mobility of the “linker” M‐domain, essential for the renaturing activity of ClpB, was demonstrated, and the size and shape of central channel were analyzed. In this model, we propose the coordinates for a loop between b4 and B6 structural elements, not defined in previous structural research, which faces the inside of the channel and may therefore play a role in substrate translocation. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 47–60, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Metabolic engineering of Escherichia coli for the production of putrescine: A four carbon diamine
Authors: Qian Zhi‐Gang , Xia Xiao‐Xia , Lee Sang Yup
Published: August 2009

A four carbon linear chain diamine, putrescine (1,4‐diaminobutane), is an important platform chemical having a wide range of applications in chemical industry. Biotechnological production of putrescine from renewable feedstock is a promising alternative to the chemical synthesis that originates from non‐renewable petroleum. Here we report development of a metabolically engineered strain of Escherichia coli that produces putrescine at high titer in glucose mineral salts medium. First, a base strain was constructed by inactivating the putrescine degradation and utilization pathways, and deleting the ornithine carbamoyltransferase chain I gene argI to make more precursors available for putrescine synthesis. Next, ornithine decarboxylase, which converts ornithine to putrescine, was amplified by a combination of plasmid‐based and chromosome‐based overexpression of the coding genes under the strong tac or trc promoter. Furthermore, the ornithine biosynthetic genes (argC‐E) were overexpressed from the trc promoter, which replaced the native promoter in the genome, to increase the ornithine pool. Finally, strain performance was further improved by the deletion of the stress responsive RNA polymerase sigma factor RpoS, a well‐known global transcription regulator that controls the expression of ca. 10% of the E. coli genes. The final engineered E. coli strain was able to produce 1.68 g L−1 of putrescine with a yield of 0.168 g g−1 glucose. Furthermore, high cell density cultivation allowed production of 24.2 g L−1 of putrescine with a productivity of 0.75 g L−1 h−1. The strategy reported here should be useful for the bio‐based production of putrescine from renewable resources, and also for the development of strains capable of producing other diamines, which are important as nitrogen‐containing platform chemicals. Biotechnol. Bioeng. 2009; 104: 651–662 © 2009 Wiley Periodicals, Inc.
Interaction of diphtheria toxin (fragment A) with actin
Authors: Bektaş Muhammet , Varol Başak , Nurten Rüstem , Bermek Engin
Published: August 2009

It was shown by gel filtration and viscosity measurements that N‐terminal fragment (FA) of diphtheria toxin (DT) can interact with both G‐ and F‐actin (filamentous actin). Elution profiles on Sephadex G‐100 indicated the formation of a binary complex of fragment A (FA) with globular actin monomer (G‐actin), which was inhibited by gelsolin. Deoxyribonuclease I (DNase I) in turn appeared to interact with this complex. Tritiated FA was found to bind to F‐actin stoichiometrically. This binding was inhibited again by gelsolin and G‐actin, but not by DNase I. The binding of FA inhibited polymerization of G‐actin and induced a time‐dependent breakdown of F‐actin under polymerization conditions. Inhibition of its ADP‐ribosyltransferase activity did not have any effect on the interactions of FA with actin. FA interacted with actin also in the cell. After treatment of human umbilical vein endothelial cells (HUVEC) with biotin‐labeled DT, Western blot analysis revealed predominantly the presence of actin in affinity‐isolated complexes of the labeled FA. Similarly, FA was found in immunoaffinity‐isolated complexes of actin. Copyright © 2009 John Wiley & Sons, Ltd.
Polymorphisms of DNA base‐excision repair genesAPE/Ref‐1andXRCC1are not associated with the risk for Graves' disease
Authors: Doğru‐Abbasoğlu Semra , Tanrıkulu Sevda , Ademoğlu Evin , Erbil Yeşim , Özderya Ayşenur , Karadağ Berrin , Uysal Müjdat
Published: August 2009

Oxidative stress has been implicated in etiopathogenesis of Graves' disease (GD). Increased lipid peroxidation and oxidative DNA damage have been found in GD patients. Oxidative DNA damage is mainly repaired by the base‐excision repair (BER) pathway. Polymorphisms in DNA‐repair genes have been associated with the increased risk of various diseases and could also be related to the etiology of GD. Therefore, we conducted a study including 197 patients with GD and age‐ and sex‐matched 303 healthy subjects to examine the role of single‐nucleotide polymorphisms of BER genes, APE/Ref‐1 (codon 148) and XRCC1 (codons 194 and 399) as a risk factor for GD. These polymorphisms were determined by quantitative real‐time PCR and melting curve analysis using LightCycler. No significant association was observed between the variant alleles of APE/Ref‐1 codon 148 [odds ratio (OR) = 0.89, 95% confidence interval (CI) = 0.69–1.17], XRCC1 codon 194 (OR = 1.24, 95% CI = 0.79–1.94), and XRCC1 codon 399 (OR = 1.12, 95% CI = 0.86–1.46) and GD. These preliminary results suggest that APE/Ref‐1 (codon 148) and XRCC1 (codons 194 and 399) polymorphisms are not significant risk factors for developing GD. Copyright © 2009 John Wiley & Sons, Ltd.
Highly Efficient Asymmetric Synthesis of Vinylic Amino Alcohols by Zn‐Promoted Benzoyloxyallylation of Chiral N‐tert‐Butanesulfinyl Imines: Facile and Rapid Access to (−)‐Cytoxazone
Authors: Liu Min , Sun Xing‐Wen , Xu Ming‐Hua , Lin Guo‐Qiang
Published: August 2009

An efficient and convenient α‐hydroxyallylation approach for the asymmetric synthesis of a variety of β‐amino‐α‐vinyl alcohols has been successfully developed. A wide range of vinylic amino alcohol derivatives could be obtained in very good yields and with excellent diastereomeric ratios of up to 99:1 in favor of anti isomers by highly diastereoselective Zn‐promoted benzoyloxyallylation of chiral N‐tert‐butanesulfinyl imines with 3‐bromopropenyl benzoate at room temperature. In particular, excellent enantioinduction of the two new stereogenic centers was observed, with up to 98 % ee. The method provides a new route for the direct α‐hydroxyallylation of imines in a highly stereoselective manner. Moreover, the synthetic value of the method has also been demonstrated by the most concise and straightforward synthesis of (−)‐cytoxazone yet reported.
Ligand Strain and the Nature of Spin Crossover in Binuclear Complexes: Two‐Step Spin Crossover in a 4,4′‐Bipyridine‐Bridged Iron(II) Complex [{Fe(dpia)(NCS)2}2(4,4′‐bpy)] (dpia=di(2‐picolyl)amine; 4,4′‐bpy=4,4′‐bipyridine)
Authors: Verat Alexander Yu. , Ould‐Moussa Nawel , Jeanneau Erwann , Le Guennic Boris , Bousseksou Azzedine , Borshch Serguei A. , Matouzenko Galina S.
Published: August 2009

The synthesis and detailed characterization of the new spin crossover (SCO) binuclear complex [{Fe(dpia)(NCS)2}2(4,4′‐bpy)] (1; dpia=di(2‐picolyl)amine, 4,4′‐bpy=4,4′‐bipyridine) are reported. Variable‐temperature magnetic susceptibility measurements show a relatively cooperative two‐step spin transition suggesting the occurrence of three spin‐state isomers: [HS–HS], [HS–LS], and [LS–LS] (HS: high spin, LS: low spin). A short plateau at 204 K separates the two steps and conforms with about 50 % of the complexes having undergone a thermal spin conversion. Routine Mössbauer spectroscopy without applying a magnetic field clearly separates four iron(II) one‐center spin states in three [HS–HS], [HS–LS], and [LS–LS] pairs and unambiguously confirms that the spin transition at the plateau temperature goes through the intermediate [HS–LS] state. The single‐crystal X‐ray structure was solved for three spin isomers at 293, 208, and 120 K. The structural study at the plateau temperature was unable to resolve the HS and LS sites in the [HS–LS] pair and only an average FeN bond length was obtained, which suggests that there is an intermediate [HS–LS] phase. The structural analysis at three temperatures revealed a dense three‐dimensional network of both intra‐ and intermolecular interactions. The relative energies of the three spin‐state isomers were evaluated by quantum‐chemical DFT calculations. Comparison of compound 1 with previously known analogues, as well as the overall analysis of structural data for numerous binuclear complexes, allowed a conclusion to be reached on the crucial role of ligand strain effects in the SCO behavior of binuclear complexes. The suggested intramolecular mechanism explains the different types of SCO observed in binuclear complexes: one‐step, two‐step, and partial (50 %) transitions.
Lewis Base Sequestered Chalcogen Dihalides: Synthetic Sources of ChX2 (Ch=Se, Te; X=Cl, Br)
Authors: Dutton Jason L. , Farrar Gregory J. , Sgro Michael J. , Battista Taylor L. , Ragogna Paul J.
Published: August 2009

The synthesis and comprehensive characterization of a series of base‐stabilized ChX2 (Ch=Se, Te; X=Cl, Br) is reported using aryl‐substituted diazabutadiene and 2,2′‐bipyridine (bipy) as the ligands. In stark contrast to free ChX2 the complexes display excellent thermal stability. Their use as viable ChX2 reagents that may be stored for later use is demonstrated in principle. The syntheses are simple and high‐yielding from commercially available or easily synthesized reagents. The bipy complexes are exceedingly rare examples of this ubiquitous ligand being utilized within Group 16 chemistry; the Se examples are the first to be characterized by X‐ray crystallography, and the Te species are only the second.
Change in the Site of Electron‐Transfer Reduction of a Zinc–Quinoxalinoporphyrin/Gold–Quinoxalinoporphyrin Dyad by Binding of Scandium Ions and the Resulting Remarkable Elongation of the Charge‐Shifted‐State Lifetime
Authors: Ohkubo Kei , Garcia Rachel , Sintic Paul J. , Khoury Tony , Crossley Maxwell J. , Kadish Karl M. , Fukuzumi Shunichi
Published: August 2009

The site of electron‐transfer reduction of AuPQ+ (PQ=5,10,15,20‐tetrakis(3,5‐di‐tert‐butylphenyl)quino‐xalino[2, 3−b′]porphyrin) and AuQPQ+ (QPQ=5,10,15,20‐tetrakis(3,5‐di‐tert‐butylphenyl)bisquinoxalino[2,3‐b′:12,13‐b′′]porphyrin) is changed from the AuIII center to the quinoxaline part of the PQ macrocycle in the presence of Sc3+ in benzonitrile because of strong binding of Sc3+ to the two nitrogen atoms of the quinoxaline moiety. Strong binding of Sc3+ to the corresponding nitrogen atoms on the quinoxaline unit of ZnPQ also occurs for the neutral form. The effects of Sc3+ on the photodynamics of an electron donor–acceptor compound containing a linked ZnII and AuIII porphyrin ([ZnPQ–AuPQ]PF6) have been examined by femto‐ and nanosecond laser flash photolysis measurements. The observed transient absorption bands at 630 and 670 nm after laser pulse irradiation in the absence of Sc3+ in benzonitrile are assigned to the charge‐shifted (CS) state (ZnPQ.+–AuPQ). The CS state decays through back electron transfer (BET) to the ground state rather than to the triplet excited state. The BET rate was determined from the disappearance of the absorption band due to the CS state. The decay of the CS state obeys first‐order kinetics. The CS lifetime was determined to be 250 ps in benzonitrile. Addition of Sc3+ to a solution of ZnPQ–AuPQ+ in benzonitrile caused a drastic lengthening of the CS lifetime that was determined to be 430 ns, a value 1700 times longer than the 250 ps lifetime measured in the absence of Sc3+. Such remarkable prolongation of the CS lifetime in the presence of Sc3+ results from a change in the site of electron transfer from the AuIII center to the quinoxaline part of the PQ macrocycle when Sc3+ binds to the quinoxaline moiety, which decelerate BET due to a large reorganization energy of electron transfer. The change in the site of electron transfer was confirmed by ESR measurements, redox potentials, and UV/Vis spectra of the singly reduced products.
Elucidating the Structure of the Pm$\bar 3$n Cubic Phase of Supramolecular Dendrimers through the Modification of their Aliphatic to Aromatic Volume Ratio
Authors: Percec Virgil , Peterca Mihai , Tsuda Yusuke , Rosen Brad M. , Uchida Satoshi , Imam Mohammad R. , Ungar Goran , Heiney Paul A.
Published: August 2009

The synthesis, and structural and retrostructural analysis of a library of second‐generation conical dendrons that self‐assemble into spherical supramolecular dendrimers is reported. This library consists of amphiphilic dendrons with n‐alkyl groups containing from 4 to 16 carbon atoms. The dendrons containing 6 to 16 carbon atoms in their n‐alkyl groups self‐assemble into spherical supramolecular dendrimers that self‐organize in a Pm$\bar 3$n cubic lattice. The structural and retrostructural analysis of the Pm$\bar 3$n lattices generated from the supramolecular dendrimers demonstrated that the volume of the aromatic core of the spherical dendrimers is not dependent on the number of carbon atoms from their alkyl groups. This result facilitated the calculation of the average values of the absolute electron density of the aliphatic and aromatic domains of the spherical supramolecular dendrimers. The relative intensity of the higher order diffraction peaks of the Pm$\bar 3$n lattice increases as the volume of the aliphatic part of the sphere mediated by the number of carbon atoms in the n‐alkyl groups decreases. This study demonstrates the maximum increase of the relative intensity of the higher order diffraction peaks of the Pm$\bar 3$n lattice generated from non‐hollow supramolecular dendrimers.
ChemInform Abstract: Enantioselective Conjugate Addition of N‐Heterocycles to α,β‐Unsaturated Ketones Catalyzed by Chiral Primary Amines.
Authors: Luo Guangshun , Zhang Shilei , Duan Wenhu , Wang Wei
Published: August 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Investigation on the Scavenging Mechanism of 1,4‐Dicarbonyls by Pyridoxamine: A Density Functional Theory Study
Authors: CHEN Xin , QIAO Qingan , CAI Zhengting , JIN Yueqing , JING Jie , SUN Xiaomin , SUN Lixiang , CAI Honglan , FENG Dacheng
Published: August 2009

The dicarbonyl compound 4‐oxopentanal (OPA) is one of the reactive carbonyl species formed in a variety of metabolic reactions in vivo, which could react with lysyl residues to form pyrrolic compounds and exhibit severe toxicity. Pyridoxamine (PM) could effectively scavenge such reactive carbonyl compounds. The reaction mechanism of PM with OPA was investigated by density functional theory (DFT) B3LYP at 6‐31G∗︁ basis level together with MP2/6‐31+G∗︁∗︁ single point calculation on the stationary points. The results indicated that this reaction could be achieved through two continuous steps. Firstly, PM and OPA would generate a tetrahydropyrrole compound via two possible reaction pathways. Subsequently, two molecules of water would be removed to achieve the final pyrrole‐type compound through two parallel paths. In addition, it is possible to form an imine intermediate in this reaction, which seems more like a by‐product from our calculation. In the end, the steric hindrance of the acetyl group was discussed. All the results agreed with experiment very well.
Manganese Dioxide Mediated Stereoselective, One‐step Synthesis of Novel Steroidal (6R)‐Spiro‐1',2′,4′‐triazoline‐3′‐thiones
Authors: SHAMSUZZAMAN  , SIDDIQUI Nazish , SALIM Anwar , AKRAM M. K.
Published: August 2009

Oxidative cyclization of 5α‐cholestan‐6‐one thiosemicarbazone (1), its 3β‐chloro (2) and 3β‐acetoxy (3) analogues with active manganese dioxide at room temperature afforded selectively the corresponding (6R)‐spiro‐1',2′,4′‐triazoline‐3′‐thiones 4–6. This synthesis has the advantages of mild reaction conditions, easy handling, easily available reagent and high yields. The products have been characterized by analytical and spectral data.
Colorimetric Sensors for Anion Recognition Based on the Proton Transfer Signaling Mechanism
Authors: HUANG Xiaohuan , HE Yongbing , CHEN Zhihong , HU Chenguang
Published: August 2009

Phenolic hydroxyl based sensors N,N‐bi(salicylidene)‐1,2‐phenylenediamine (1), 2‐[(4‐nitrophenylimino)‐ methyl] phenol (2) and 2‐[p‐tdylimino methyl] phenol (3) bearing Schiff‐base groups can act as selective colorimetric sensors for anions, which exhibit distinct color changes in the presence of fluoride, but show no response to other halogen anions. They also give response to acetate, which is clearly visible to the naked eyes. The selectivity can be rationalized on the proton transfer signaling mechanism. The sensor 1 containing plural phenolic groups undergoes stepwise deprotonation of the two O–H fragments when it interacts with excess fluoride, which is confirmed by UV‐Vis, 1H NMR and 19F NMR spectroscopic methods.
Synthesis of Novel Bis‐spiroisoxazolines through 1,3‐Dipolar Cycloaddition of Nitrile Oxide with α,α'‐Bis(arylmethylidene)cycloalkanone
Authors: LI Xiaofang , YU Xianyong , FENG Yaqing
Published: August 2009

A new class of bis‐spiroisoxazolines were prepared in moderate to good yields in a highly regioselective cycloaddition of nitrile oxide with bis(arylmethylidene)cycloalkanone. The structures of the products were characterized thoroughly by IR, elemental analysis, NMR together with X‐ray crystallographic analysis. The result of crystal diffraction indicates that this 1,3‐dipolar cycloaddition has high regioselectivity. The density functional calculations provide a reasonable explanation on the regioselectivity for the cycloaddition reaction.
Synthesis of Thermostable Azo‐type Photoswitches towards Photoregulating Nucleic Acid Structures
Authors: WANG Qi , GAO Shuang , ZHOU Kai , CHEN Wenbin , NIU Congwei , XI Zhen
Published: August 2009

In order to design efficient and thermostable azo‐type regulators, a series of azo‐type compounds were synthesized and characterized. While introducing an inductive electron‐withdrawing group to an azobenzene para or meta‐position, the obtained compound can be an excellent photoswitch. 3,3′‐Azo‐di‐benzyl alcohol was designed and synthesized as one of thermostable and efficient photoswitches, which can efficiently reversibly photoregulate the nucleic acid structure with its cis‐isomer being sufficiently stable at physiological temperature.
Synthesis of a Number of 3‐Alkyl Substituted Pyrrole Monomers
Authors: CAI Xuediao , JAEHNE Evelin , ADLER Hans‐Juergen
Published: August 2009

The problem of delamination of electro‐deposited polypyrrole (PPY) layers on several substrates can be avoided by using an adhesion promoting system. A new class of compounds–ω‐(pyrrol‐3‐yl)alkylphosphonic acids have been designed to link polypyrrole layers covalently to metal oxide surfaces. Synthetic routes, which lead to the formation of 3‐substituted pyrroles with surface active groups are described. The synthesis and characterization are shown in detail. 1‐Phenylsulfonyl pyrrole was utilized as a precursor in the synthesis of 3‐substituted pyrroles via Friedel‐Crafts acylation reaction. Subsequently, two methods were used to synthesize ω‐(pyrrol‐3‐yl)alkylpho‐ sphonic acid esters. One starts from the brominated oxoalkyl derivatives by removing the protecting group followed by reduction yielding ω‐(pyrrol‐3‐yl)alkylphosphonic acid esters. This method is suitable for hexyl or longer chain derivatives. The other is the reduction of carbonyl group followed by de‐protection, which is successful for short as well as long chain derivatives. Finally, ω‐(pyrrol‐3‐yl)alkylphosphonic acids were obtained by hydrolysis of the ester derivatives.
An Unexpected and Efficient Synthesis of Open‐chain Derivatives of Bistetronic Acid under Microwave Irradiation
Authors: SHI Feng , MA Ning , ZHOU Dianxiang , ZHANG Ge , JIANG Bo , TU Shujiang
Published: August 2009

An unexpected and efficient synthesis of novel open‐chain derivatives of bistetronic acid has been successfully achieved in glyclol under microwave irradiation (MW). This method has the prominent advantages of short reaction time, high yield, operational simplicity as well as environmental friendliness.
Synthesis and Properties of Poly(vinyl alcohol)/Synthetic F‐montmorillonite Nanocomposites
Authors: ZHANG Junhao , CHENG Xiaofang , LIU He , LU Weiliang
Published: August 2009

F‐montmorillonite (F‐MMT) was synthesized by a hydrothermal method at 493 K for 72 h, in which a little of hydroxyl radical is replaced by fluoride ion in the silicate structure. Poly(vinyl alcohol) (PVA)/F‐MMT nanocomposites were prepared using the synthetic F‐MMT by a solution‐intercalation method. The F‐MMT and PVA/ F‐MMT nanocomposites were characterized by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the flake structured F‐MMT is homogeneously dispersed in PVA, forming an exfoliated nanocomposite structure. Thermogravimetric analysis, mechanical performance and UV‐visible spectroscopy were applied to test the properties of PVA nanocomposites, which indicate that the thermal stability and mechanical performance are enhanced distinctly, without a sacrifice in optical clarity. The improvement of mechanical and thermal properties was attributed to the homogeneous and good dispersion of F‐MMT in polymeric matrix and the strong hydrogen bonding between O��H of PVA and F�� of F‐MMT.