bluuebunny/crossref_metadata_2025 huggingface dataset:
Making sense of zebrafish neural development in the Minervois
Authors: Ghysen Alain , Dambly-Chaudière Christine , Raible David
Published: August 2007

The meeting 'From sensory perception to motor output: genetic bases of behavior in the zebrafish embryo' was held at Minerve (South of France) on March 16–18, 2007. The meeting site was beautifully situated in the heart of the Minervois wine country, and its remoteness promoted conversations and interaction over the course of the program. The meeting covered neurogenesis and eye development on day 1, ear and lateral line development on day 2, and brain connectivity and behavior on day 3. Underlying all sessions, however, ran the growing importance of live imaging, an approach that takes full advantage of the transparency of fish embryos and early larvae, as illustrated by several movies and links in this report.
Glucosamine prevents in vitro collagen degradation in chondrocytes by inhibiting advanced lipoxidation reactions and protein oxidation
Authors: Tiku Moti L , Narla Haritha , Jain Mohit , Yalamanchili Praveen
Published: August 2007

Osteoarthritis (OA) affects a large segment of the aging population and is a major cause of pain and disability. At present, there is no specific treatment available to prevent or retard the cartilage destruction that occurs in OA. Recently, glucosamine sulfate has received attention as a putative agent that may retard cartilage degradation in OA. The precise mechanism of action of glucosamine is not known. We investigated the effect of glucosamine in an in vitro model of cartilage collagen degradation in which collagen degradation induced by activated chondrocytes is mediated by lipid peroxidation reaction. Lipid peroxidation in chondrocytes was measured by conjugated diene formation. Protein oxidation and aldehydic adduct formation were studied by immunoblot assays. Antioxidant effect of glucosamine was also tested on malondialdehyde (thiobarbituric acid-reactive substances [TBARS]) formation on purified lipoprotein oxidation for comparison. Glucosamine sulfate and glucosamine hydrochloride in millimolar (0.1 to 50) concentrations specifically and significantly inhibited collagen degradation induced by calcium ionophore-activated chondrocytes. Glucosamine hydrochloride did not inhibit lipid peroxidation reaction in either activated chondrocytes or in copper-induced oxidation of purified lipoproteins as measured by conjugated diene formation. Glucosamine hydrochloride, in a dose-dependent manner, inhibited malondialdehyde (TBARS) formation by oxidized lipoproteins. Moreover, we show that glucosamine hydrochloride prevents lipoprotein protein oxidation and inhibits malondialdehyde adduct formation in chondrocyte cell matrix, suggesting that it inhibits advanced lipoxidation reactions. Together, the data suggest that the mechanism of decreasing collagen degradation in this in vitro model system by glucosamine may be mediated by the inhibition of advanced lipoxidation reaction, preventing the oxidation and loss of collagen matrix from labeled chondrocyte matrix. Further studies are needed to relate these in vitro findings to the retardation of cartilage degradation reported in OA trials investigating glucosamine.
Heregulin β1 drives gefitinib-resistant growth and invasion in tamoxifen-resistant MCF-7 breast cancer cells
Authors: Hutcheson Iain R , Knowlden Janice M , Hiscox Steve E , Barrow Denise , Gee Julia MW , Robertson John F , Ellis Ian O , Nicholson Robert I
Published: August 2007

Introduction

Resistance to anti-epidermal growth factor receptor (anti-EGFR) therapies is an emerging clinical problem. The efficacy of anti-EGFR therapies can be influenced by the presence of heregulins (HRGs), which can bind erbB3/4 receptors and can activate alternative signalling pathways. In the present study we have examined whether HRG signalling can circumvent EGFR blockade in an EGFR-positive tamoxifen-resistant MCF-7 (Tam-R) breast cancer cell line.

Methods

Tam-R cells, incubated with the selective EGFR tyrosine kinase inhibitor gefitinib ('Iressa', ZD1839), were exposed to HRGβ1 and the effects on erbB receptor dimerization profiles and on activation of associated downstream signalling components were assessed by immunoprecipitation, western blotting and immunocytochemistry. The effects of HRGβ1 on gefitinib-treated Tam-R cell growth and invasion were also examined, and HRGβ1 expression levels were assessed in breast cancer tissue by immunohistochemistry to address the potential clinical relevance of such a resistance mechanism.

Results

In Tam-R cells, HRGβ1 promoted erbB3/erbB2 and erbB3/EGFR heterodimerization, promoted ERK1/2 and AKT pathway activation and increased cell proliferation and invasion. Gefitinib prevented HRGβ1-driven erbB3/EGFR heterodimerization, ERK1/2 activation and Tam-R cell proliferation, but HRGβ1-driven erbB3/erbB2 heterodimerization, AKT activation and Tam-R cell invasion were maintained. A combination of gefitinib and the phosphatidylinositol 3-kinase inhibitor LY294002 effectively blocked HRGβ1-mediated intracellular signalling activity, growth and invasion in Tam-R cells. Similarly, targeting erbB2 with trastuzumab in combination with gefitinib in Tam-R cells reduced HRGβ1-induced erbB2 and ERK1/2 activity; however, HRGβ1-driven AKT activity and cell growth were maintained while cell invasion was significantly enhanced with this combination. In clinical tissue all samples demonstrated cytoplasmic tumour epithelial HRGβ1 protein staining, with expression correlating with EGFR positivity and activation of both AKT and ERK1/2.

Conclusion

HRGβ1 can overcome the inhibitory effects of gefitinib on cell growth and invasion in Tam-R cells through promotion of erbB3/erbB2 heterodimerization and activation of the phosphatidylinositol 3-kinase/AKT signalling pathway. This may have implications for the effectiveness of anti-EGFR therapies in breast cancer as HRGβ1 is enriched in many EGFR-positive breast tumours.
IFN-α regulates Toll-like receptor-mediated IL-27 gene expression in human macrophages
Authors: Pirhonen Jaana , Sirén Jukka , Julkunen Ilkka , Matikainen Sampsa
Published: August 2007

IL-27 is a novel member of the IL-12 cytokine family. IL-27 has pro- and anti-inflammatory properties, and it controls the responses of adaptive immunity. It promotes the differentiation of naïve Th cells and suppresses the effector functions of Th17 cells. Biologically active IL-27 is a heterodimer composed of EBV-induced gene 3 (EBI3) and p28 proteins. We report that TLR-dependent expression of IL-27 in human macrophages is mediated by IFN-α. Stimulation of macrophages with agonists for TLR3 {polyinosinic:polycytidylic acid [poly(I:C)]}, TLR4 (LPS), or TLR7/8 (R848) results in concurrent expression of EBI3 and p28. The p28 expression is inhibited with neutralizing anti-IFN-α antibodies. Unlike poly(I:C), LPS, and R848, TLR2 agonist (S)-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-N-palmitoyl-(R)-Cys-(S)-Ser(S)-Lys4-OH trihydrochloride does not stimulate macrophages to produce IFN-α, and therefore, it is not able to turn on the expression of p28. There is an IFN-stimulated response element (ISRE) in the p28 gene promoter. IFN-α enhances the expression of IFN regulatory factor 1 (IRF-1) in macrophages and induces binding of IRF-1 to the p28 ISRE site. The data provide a mechanistic basis for the IFN-α-mediated activation of IL-27. The data emphasize a role of IFN-α in immune responses, which rely on the recognition of pathogens by TLRs.
Blockade of chronic graft-versus-host disease by alloantigen-induced CD4+CD25+Foxp3+ regulatory T cells in nonlymphopenic hosts
Authors: Giorgini A , Noble A
Published: August 2007

CD4+CD25+ regulatory T cells (Tregs) are well known to suppress immunopathology induced in lymphopenic animals following T cell reconstitution, including acute graft-versus-host disease (GVHD) post-bone marrow transplantation. The regulatory potential of this subset in nonlymphopenic hosts and in chronic, Th2-mediated GVHD is less clear. We have generated alloantigen-specific cells from CD4+CD25+ populations stimulated with MHC-disparate dendritic cells and found them to express a stable Treg forkhead box p3+ phenotype with enhanced suppressive activity mediated by cell contact. When transferred into nonlymphopenic F1 hosts, nonspecific Tregs proliferated as rapidly as CD4+CD25− cells but displayed distinct growth kinetics in vitro. Tregs, expanded in response to alloantigen in vitro, displayed greatly enhanced suppressive activity, which was partially antigen-specific. They were effective inhibitors of chronic GVHD, blocking donor cell engraftment, splenomegaly, autoantibody production, and glomerulonephritis. CD25+ and CD25− cells were equally susceptible to inhibition by immunosuppressive drugs targeting TCR signaling and rapamycin, but Tregs were resistant to inhibition by dexamethasone. The data indicate that alloantigen-driven expansion, rather than homeostatic proliferation, is key to the effectiveness of CD4+CD25+ Tregs in GVHD and suggest that cellular therapy with alloantigen-induced Tregs in combination with glucocorticoid treatment would be effective in prevention of chronic GVHD after immune reconstitution.
Scholastic Achievements of Childhood Leukemia Patients: A Nationwide, Register-Based Study
Authors: Harila-Saari Arja H. , Lähteenmäki Päivi M. , Pukkala Eero , Kyyrönen Pentti , Lanning Marjatta , Sankila Risto
Published: August 2007

Purpose

Studies concerning the scholastic achievement of survivors of childhood leukemia have yielded controversial results. We studied the school marks of childhood leukemia survivors in a register-based study.

Patients and Methods

Three hundred seventy-one patients with a diagnosis of leukemia before the age of 16 years who were born between 1974 and 1986 and alive on their 16th birthday were identified from the Finnish Cancer Registry. Five matched controls were sought for each patient from the Population Register Center of Finland. Information on the ninth-grade school report was obtained from Statistics Finland. The overall mark average and the marks (scale 4 to 10) for mother tongue, foreign language, mathematics, and physical education were compared between the patients and controls.

Results

The ninth-grade school report was obtained by 97.6% of the patients and 98.5% of the controls. The patients whose treatment included cranial irradiation had a lower overall mark average (mean difference, −0.24; 95% CI, −0.33 to −0.15) and lower marks for all assessed school subjects compared with their controls. Of the patients treated with chemotherapy alone, only the females with leukemia diagnosed before 7 years of age had lower school marks than their controls. The biggest difference was observed in the marks for foreign language among the irradiated females diagnosed at a young age (mean difference, −1.0; 95% CI, −1.25 to −0.74).

Conclusion

Leukemia treatment that includes cranial irradiation impairs scholastic achievement. It is noteworthy that treatment of leukemia with chemotherapy alone impairs school performance only in females diagnosed before school age.
Trastuzumab-Related Cardiotoxicity: Calling Into Question the Concept of Reversibility
Authors: Telli Melinda L. , Hunt Sharon A. , Carlson Robert W. , Guardino Alice E.
Published: August 2007

Purpose

To assess the spectrum and reversibility of the cardiotoxicity observed in the adjuvant trastuzumab trials.

Design

The design and efficacy of the major adjuvant trastuzumab trials was assessed, including the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-31, North Central Cancer Treatment Group N9831, Herceptin Adjuvant, Breast Cancer International Research Group 006, and Finland Herceptin trials. The cardiotoxicity data were evaluated with a focus on the follow-up cardiac evaluations of women who were diagnosed with cardiotoxicity. Proposed mechanisms of trastuzumab-related cardiotoxicity were considered. The natural history of congestive heart failure (CHF) was reviewed with the goal of placing the trastuzumab experience in context.

Results

Up to 4% of patients enrolled onto the adjuvant trastuzumab trials experienced severe CHF during treatment. In these trials, early stopping rules that identified an unacceptable level of cardiotoxicity were never reached. Despite this, a large number of patients on these trials experienced some form of cardiotoxicity that ultimately required discontinuation of trastuzumab. Approximately 14% of patients in the NSABP B-31 trial discontinued trastuzumab because of asymptomatic decreases in left ventricular ejection fraction (LVEF). Results of follow-up cardiac evaluations of patients diagnosed with any degree of cardiotoxicity in the NSABP B-31 trial document that a clinically significant proportion of patients have sustained decrements in their LVEF to less than 50%.

Conclusion

Adjuvant trastuzumab provides substantial benefits to patients with human epidermal growth factor receptor 2–positive breast cancer, however, competing immediate and long-term cardiovascular risks are a great concern. Continued cardiac follow-up of these women is of critical importance.
Receipt of Appropriate Primary Breast Cancer Therapy and Adjuvant Therapy Are Not Associated With Obesity in Older Women With Access to Health Care
Authors: Buist Diana S.M. , Ichikawa Laura , Prout Marianne N. , Yood Marianne Ulcickas , Field Terry S. , Owusu Cynthia , Geiger Ann M. , Quinn Virginia P. , Wei Feifei , Silliman Rebecca A.
Published: August 2007

Purpose

Many studies have reported body mass index (BMI) increases the risk of breast cancer recurrence and breast cancer–specific mortality. Few studies have reported or examined whether breast cancer treatment differs by BMI. The purpose of this study was to examine the association between BMI at breast cancer diagnosis and receipt of appropriate primary tumor therapy and adjuvant therapy.

Methods

We identified 897 women age ≥ 65 years diagnosed with stage I or II breast cancer from 1990 to 1999 at five health care organizations. We used medical records to confirm demographics, tumor characteristics, treatment, comorbid conditions, and to calculate BMI at diagnosis (< 25 kg/m2, n = 328; 25 to < 30 kg/m2, n = 305; 30 to < 35 kg/m2, n = 188; ≥ 35 kg/m2, n = 76). We defined primary therapy based on National Guidelines as receiving breast-conserving surgery with radiation therapy and axillary node dissection, simple mastectomy with axillary node dissection, or modified radical mastectomy (73% overall); adjuvant therapy was defined as receipt of hormonal therapy, chemotherapy, or both (60% overall).

Results

The median BMI was 26.7 kg/m2 (range, 14.6 to 61.2). The proportion of women receiving primary therapy and adjuvant therapy was lowest for women less than 25 kg/m2 (69% and 56%, respectively) and greatest for obese I (78% and 64%, respectively). There were no differences in receipt of primary or adjuvant treatment across BMI in univariate or multivariable models (after adjusting for age, stage, comorbidity, diagnosis year, and hormone receptor positivity).

Conclusion

Receipt of appropriate primary therapy and adjuvant therapy is not associated with BMI in older women with access to health care. Additional research in larger samples and more diverse settings is needed.
Limitations of Peripheral Quantitative Computed Tomography Metaphyseal Bone Density Measurements
Authors: Lee David C. , Gilsanz Vicente , Wren Tishya A. L.
Published: August 2007

Context: Peripheral quantitative computed tomography (pQCT) measurements are frequently obtained to assess cancellous bone density in the appendicular skeleton. Large variations in bone morphology associated with skeletal development may limit the interpretation of pediatric pQCT studies based on a single slice.

Objective: The objective of the study was to characterize the variability in trabecular bone density values along the length of the metaphysis.

Design: The design was an analysis of pQCT bone density data.

Setting: The study was conducted at a hospital radiology department.

Patients: The study included 35 children with cerebral palsy aged 6–12 yr.

Main Outcome Measure: Variations in cancellous bone density along the length of the proximal tibial metaphysis were measured.

Results: The patterns of decay in metaphyseal trabecular bone density were different in all subjects, and the density changed from the physis to the shaft at a rate of 16.8 ± 8.2% per 1 mm (range 8.6–37.9% per 1 mm). The slopes of the density curve drastically changed in some children over a short period of 6 months. Even with a high correlation (r2 = 0.88) between the density of a slice located a fixed distance from the growth plate and the overall mean metaphysis density, the respective changes in density over 6 months were only moderately correlated (r2 = 0.58).

Conclusions: These results underscore the difficulty in interpreting metaphyseal pQCT bone density measurements from a single slice and highlight the need for developing pQCT acquisition techniques that provide more representative bone density determinations in the appendicular skeleton of children.
National Health and Nutrition Examination Survey III Thyroid-Stimulating Hormone (TSH)-Thyroperoxidase Antibody Relationships Demonstrate That TSH Upper Reference Limits May Be Skewed by Occult Thyroid Dysfunction
Authors: Spencer C. A. , Hollowell J. G. , Kazarosyan M. , Braverman L. E.
Published: August 2007

Context: The setting of the TSH upper reference limit impacts the diagnosis of mild hypothyroidism and is currently controversial.

Objective: Our objective was to evaluate factors influencing the TSH reference range.

Design: Nonpregnant subjects aged 12 yr and older from National Health and Nutrition Examination Survey III were used to study the relationships between TSH, thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies in different ethnic groups.

Results: TPOAb prevalence was lowest (<3%) when TSH was between 0.1 and 1.5 mIU/liter in women and between 0.1 and 2.0 mIU/liter in men and progressively increased to above 50% when TSH exceeded 20 mIU/liter. TSH reference range parameters (2.5th, 50th, and 97.5th percentiles) were analyzed according to thyroid antibody status, race/ethnicity, and age for the 14,202 subjects made up of non-Hispanic Blacks (B), non-Hispanic whites (W), and Mexican-Americans (M) who did not report thyroid disease or taking thyroid-altering medications and whose total T4 was within the reference range. For each age group of each ethnicity, the inclusion of antibody-positive subjects increased TSH medians and upper limits (97.5th percentiles). The TSH upper limit was lower for the entire B cohort vs. W or M. However, this difference was lost when age cohorts with a similar prevalence of TPOAb (B age 40–49 yr vs. W and M age 20–29 yr) were compared.

Conclusions: Ethnic differences in TSH were not present when populations with the same relative frequency of thyroid antibodies were compared. TSH upper reference limits may be skewed by TPOAb-negative individuals with occult autoimmune thyroid dysfunction.
Amino-Terminal Propeptide of C-Type Natriuretic Peptide and Linear Growth in Children: Effects of Puberty, Testosterone, and Growth Hormone
Authors: Olney Robert C. , Prickett Timothy C. R. , Yandle Timothy G. , Espiner Eric A. , Han Joan C. , Mauras Nelly
Published: August 2007

Context: C-type natriuretic peptide (CNP), a paracrine factor of the growth plate, plays a key role in stimulating bone growth. The amino-terminal propeptide of CNP (NTproCNP) is produced in equimolar amounts with CNP and is measurable in plasma, providing a potential biomarker for growth plate activity and, hence, linear growth.

Objective: We explored the effects of puberty, testosterone, and GH treatment on NTproCNP levels in normal and short-statured children.

Design: This was a retrospective analysis of samples obtained during previous studies.

Setting: The study was conducted at a pediatric clinical research center.

Subjects: Children with short stature due to GH deficiency, idiopathic short stature (ISS), or constitutional delay of growth and maturation (CDGM) were studied (n = 37). A cohort of normal-statured adolescent boys was also studied (n = 23).

Interventions: Children with GH deficiency and ISS were studied before and during testosterone and/or GH treatment. Boys with CDGM and healthy controls were studied once.

Main Outcome Measures: The main outcomes were NTproCNP levels before and during growth-promoting therapy and during pubertal growth.

Results: Children with short stature due to GH deficiency, ISS, or CDGM had comparable baseline levels of NTproCNP, and levels increased markedly in response to GH or testosterone treatment. In boys with CDGM, levels were comparable with height-matched controls but were less than those from age-matched controls. In healthy boys, NTproCNP appears to peak with the pubertal growth spurt.

Conclusions: NTproCNP levels increase during growth-promoting therapy and are increased during puberty in boys. This novel biomarker of growth may have clinical utility in the evaluation of children with short stature and for monitoring growth-promoting therapy.
Modulation of lamellipodial structure and dynamics by NO-dependent phosphorylation of VASP Ser239
Authors: Lindsay Susan L. , Ramsey Sara , Aitchison Michael , Renné Thomas , Evans Thomas J.
Published: August 2007

The initial step in directed cell movement is lamellipodial protrusion, an action driven by actin polymerization. Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family proteins are key regulators of this actin polymerization and can control lamellipodial protrusion rate. Ena/VASP proteins are substrates for modification by cyclic-nucleotide-dependent protein kinases at a number of sites. Phosphorylation of Ser239 of VASP in vitro inhibits its anti-capping and filament-bundling activity but the effects of this modification on lamellipodial structure and function are unknown. To examine the functional effects of this modification in living cells, we studied VASP phosphorylation at Ser239 by nitric oxide (NO) stimulation of cGMP-dependent protein kinase. Using live cell imaging of primary cells transfected with GFP-VASP constructs, we found that NO produced rapid retraction of lamellipodia together with cell rounding that was dependent on guanylate cyclase and type II cGMP-dependent protein kinase. In cells expressing a mutant VASP (Ser239Ala) lacking the site preferentially phosphorylated by this kinase, NO had no effect. Phosphorylation of Ser239 of VASP results in loss of lamellipodial protrusions and cell rounding, and is a powerful means of controlling directed actin polymerization within lamellipodia.
UNC-87, a calponin-related protein in C. elegans, antagonizes ADF/cofilin-mediated actin filament dynamics
Authors: Yamashiro Sawako , Gimona Mario , Ono Shoichiro
Published: August 2007

Stabilization of actin filaments is critical for supporting actomyosin-based contractility and for maintaining stable cellular structures. Tropomyosin is a well-characterized ubiquitous actin stabilizer that inhibits ADF/cofilin-dependent actin depolymerization. Here, we show that UNC-87, a calponin-related Caenorhabditis elegans protein with seven calponin-like repeats, competes with ADF/cofilin for binding to actin filaments and inhibits ADF/cofilin-dependent filament severing and depolymerization in vitro. Mutations in the unc-87 gene suppress the disorganized actin phenotype in an ADF/cofilin mutant in the C. elegans body wall muscle, supporting their antagonistic roles in regulating actin stability in vivo. UNC-87 and tropomyosin exhibit synergistic effects in stabilizing actin filaments against ADF/cofilin, and direct comparison reveals that UNC-87 effectively stabilizes actin filaments at much lower concentrations than tropomyosin. However, the in vivo functions of UNC-87 and tropomyosin appear different, suggesting their distinct roles in the regulation of actomyosin assembly and cellular contractility. Our results demonstrate that actin binding via calponin-like repeats competes with ADF/cofilin-driven cytoskeletal turnover, and is critical for providing the spatiotemporal regulation of actin filament stability.
Analysis of GTPase-activating proteins: Rab1 and Rab43 are key Rabs required to maintain a functional Golgi complex in human cells
Authors: Haas Alexander K. , Yoshimura Shin-ichiro , Stephens David J. , Preisinger Christian , Fuchs Evelyn , Barr Francis A.
Published: August 2007

Rab GTPases control vesicle movement and tethering membrane events in membrane trafficking. We used the 38 human Rab GTPase activating proteins (GAPs) to identify which of the 60 Rabs encoded in the human genome function at the Golgi complex. Surprisingly, this screen identified only two GAPs, RN-tre and TBC1D20, disrupting both Golgi organization and protein transport. RN-tre is the GAP for Rab43, and controls retrograde transport into the Golgi from the endocytic pathway. TBC1D20 is the ER-localized GAP for Rab1, and is the only GAP blocking the delivery of secretory cargo from the ER to the cell surface. Strikingly, its expression causes the loss of the Golgi complex, highlighting the importance of Rab1 for Golgi biogenesis. These effects can be antagonized by reticulon, a binding partner for TBC1D20 in the ER. Together, these findings indicate that Rab1 and Rab43 are key Rabs required for the biogenesis and maintenance of a functional Golgi structure, and suggest that other Rabs acting at the Golgi complex are likely to be functionally redundant.
Effect of target secondary structure on RNAi efficiency
Authors: Shao Yu , Chan Chi Yu , Maliyekkel Anil , Lawrence Charles E. , Roninson Igor B. , Ding Ye
Published: August 2007

RNA interference (RNAi) mediated by small interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs) has become a powerful tool for gene knockdown studies. However, the levels of knockdown vary greatly. Here, we examine the effect of target disruption energy, a novel measure of target accessibility, along with other parameters that may affect RNAi efficiency. Based on target secondary structures predicted by the Sfold program, the target disruption energy represents the free energy cost for local alteration of the target structure to allow target binding by the siRNA guide strand. In analyses of 100 siRNAs and 101 shRNAs targeted to 103 endogenous human genes, we find that the disruption energy is an important determinant of RNAi activity and the asymmetry of siRNA duplex asymmetry is important for facilitating the assembly of the RNA-induced silencing complex (RISC). We estimate that target accessibility and duplex asymmetry can improve the target knockdown level significantly by nearly 40% and 26%, respectively. In the RNAi pathway, RISC assembly precedes target binding by the siRNA guide strand. Thus, our findings suggest that duplex asymmetry has significant upstream effect on RISC assembly and target accessibility has strong downstream effect on target recognition. The results of the analyses suggest criteria for improving the design of siRNAs and shRNAs.
The Saccharomyces cerevisiae Pus2 protein encoded by YGL063w ORF is a mitochondrial tRNA:Ψ27/28-synthase
Authors: Behm-Ansmant Isabelle , Branlant Christiane , Motorin Yuri
Published: August 2007

The RNA:pseudouridine (Ψ)-synthase family is one of the most complex families of RNA modification enzymes. Ten genes encoding putative RNA:Ψ-synthases have been identified in S. cerevisiae. Most of the encoded enzymes have been characterized experimentally. Only the putative RNA:Ψ-synthase Pus2p (encoded by the YGL063w ORF) had no identified substrate. Here, we analyzed Ψ residues in cytoplasmic and mitochondrial tRNAs extracted from S. cerevisiae strains, carrying disruptions in the PUS1 and/or PUS2 ORFs. Our results demonstrate that Pus2p is a mitochondrial-specific tRNA:Ψ-synthase acting at positions 27 and 28 in tRNAs. The importance of the Asp56 residue in the conserved ARTD motif of the Pus2p catalytic site is demonstrated in vivo. Interestingly, in spite of the absence of a characteristic N-terminal targeting signal, our data strongly suggest an efficient and rapid targeting of Pus2p in yeast mitochondria. In contradiction with the commonly held idea that a unique nuclear gene encodes the enzyme required for both cytoplasmic and mitochondrial tRNA modifications, here we show the existence of an enzyme specifically dedicated to mitochondrial tRNA modification (Pus2p), the corresponding modification in cytoplasmic tRNAs being catalyzed by another protein (Pus1p).
Treatment Options in Steroid-Refractory Acute Graft-Versus-Host Disease Following Hematopoietic Stem Cell Transplantation
Authors: Kim Sara S
Published: August 2007

Objective:

To evaluate the treatment options in steroid-refractory acute graft-versus-host disease (GVHD) following hematopoietic stem cell transplantation.

Data Sources:

Literature was obtained by searching MEDLINE (1966–May 2007) and EMBASE (1980–May 2007).

Study Selection and Data Extraction:

All pertinent clinical trials, retrospective studies, case reports, and compassionate use studies were identified and evaluated for safety and efficacy of the pharmacologic agents.

Data Synthesis:

Steroid-refractory acute GVHD is associated with high rates of morbidity and mortality. Although various pharmacologic agents have been studied in the treatment of steroid-refractory acute GVHD, no treatments have been established as a salvage therapy. Preliminary data on different pharmacologic agents have been identified and evaluated for their efficacy and tolerability in the treatment of steroid-refractory acute GVHD. The effects of the pharmacologic agents varied significantly among patients: severity of the disease, involvement of different organs, and the patient's age seem to be the major factors that affect an individual's response to drug therapy. In addition, the treatments are further challenged by the high incidence of potentially fatal opportunistic infections that occur during the therapy.

Conclusions:

Selection of pharmacologic agents for the treatment of steroid-refractory acute GVHD should be based on the target organs, adverse drug reactions, and economic factors. Further studies with larger sample sizes are warranted to better understand the roles of these agents in the treatment of steroid-refractory acute GVHD.
Knotwood as a window to the indirect measurement of the decay resistance of Scots pine heartwood
Authors: Karppanen Outi , Venäläinen Martti , Harju Anni M. , Willför Stefan , Pietarinen Suvi , Laakso Tapio , Kainulainen Pirjo
Published: August 2007

There is wide variation in the extractive content and decay resistance of Scots pine (Pinus sylvestris L.) heartwood. The heartwood is not visible in standing trees and only poorly visible in timber. Therefore, it is difficult to identify extractive-rich trees, and consequently the most decay-resistant heartwood. On the other hand, knots are clearly visible in standing trees and timber. In the present paper we studied the possibility of measuring the decay resistance of Scots pine heartwood indirectly on the basis of the extractive concentration of knotwood. The material investigated consisted of 40 felled trees with a wide between-tree variation for extractive content and decay resistance of their heartwood. The extractive content of knotwood was found to be four- to five-fold higher than that of heartwood. Statistically significant correlations were found between the mass loss of heartwood and the concentrations of total phenolics and stilbenes in knotwood (r=-0.54, P<0.001 and r=-0.40, P=0.011, respectively), and for the concentration of total phenolics (r=0.42, P=0.008) and stilbenes (r=0.39, P=0.012) between heartwood and knotwood. We suggest further development of this technique in the context of rapid industrial screening of durable pine heartwood.
Thermoforming of wood veneer composite sheets
Authors: Srinivasan Narayana , Bhattacharyya Debes , Jayaraman Krishnan
Published: August 2007

Thermoforming of wood veneers into profiles is a novel idea and the focus of this paper is to study the formability characteristics of thin radiata pine (Pinus radiata D. Don) veneers, which are generally used as surface coverings. Radiata pine is well suited as a raw material for furniture, joinery, and interior architectural products. This is because it has excellent turning, shaping, and laminating properties and readily achieves brilliant stain and paint finishes. In this study, radiata pine veneers were softened by immersion in a hot water bath and then thermoformed by means of heated dies/moulds. The formability characteristics were investigated by conducting single-curvature V-bending tests. The influence of the forming method on the shape conformance of softened veneers under single- and multiple-bend conditions was examined. The paper also discusses the influences of manufacturing parameters that include the softening method, the die temperature, the duration of forming, the ratio of bend radius to veneer thickness, and the veneer architecture. The study clearly establishes the feasibility of forming veneers into multi-bend products in a semi-continuous manner using matched dies.
Stabilization of H2O2 in the presence of Fe(II) and Mn(II) impurities under alkaline conditions
Authors: Popov Evgeny , Välisaari Jouni , Vuorenpalo Veli-Matti , Aksela Reijo , Eloranta Jussi
Published: August 2007

Stabilization of aqueous H2O2 solutions containing small amounts of transition metal impurities [e.g., Mn(II) and Fe(II)] was studied in terms of UV/Vis and electron spin resonance spectroscopy and oxygen concentration measurements at pH ∼11. The results show that aspartic acid diethoxy succinate (AES) could stabilize H2O2 solutions when Mn(II) and Fe(II) were present. Diethylenetriamine pentaacetic acid (DTPA) showed similar behavior, but was not able to stabilize the solutions as efficiently as AES. In the long-term regime, Na-poly-alpha-hydroxy-acrylate was almost as effective a stabilizing agent as AES. Na-acrylate-3-allyloxide-2-hydroxy propane Na-sulfonate copolymer (Aqualic) could decrease H2O2 decomposition by one order of magnitude, but it was the least efficient stabilizing agent among the substances studied. Furthermore, generation of superoxide radical was not suppressed in the presence of Aqualic.
Characterization of non-cellulosic glucans in Eucalyptus globulus Labill. wood and kraft pulp
Authors: Lisboa Sara A. , Evtuguin Dmitry V. , Pascoal Neto Carlos
Published: August 2007

The amount of non-cellulosic glucans in Eucalyptus globulus wood (approx. 4.5%) was assessed by extraction of sawdust with a 0.5 M NaOH solution at 90–120°C and the structural features were elucidated in a glucan-enriched polysaccharide fraction isolated by hot water extraction (120°C, 2 h). Isolated soluble glucans were characterized by wet chemistry methods and a set of 1D and 2D NMR techniques. The major proportion of glucans consisted of amylose (20%) and amylopectin (80%), although a small proportion of β-(1→3)-glucan (<0.2% on wood weight) was also detected. Although glucans are easily removed in the initial phase of kraft pulping, notable amounts were found in unbleached pulp and it was supposed that in the final stage of kraft pulping a fraction of α-glucan is precipitated onto the fiber surface and contributes to the pulp yield.
Using GOMS for Modeling Routine Tasks Within Complex Sociotechnical Systems: Connecting Macrocognitive Models to Microcognition
Authors: West Robert L. , Nagy Gabriella
Published: August 2007

Cognitive modeling has not yet played much of a role in the study of sociotechnical systems. Arguably, this is because most cognitive modeling systems were originally created to model microcognitive results, not the types of macrocognitive behaviors that drive sociotechnical systems (Klein et al., 2003). However, this does not mean that cognitive modeling systems cannot be adapted to deal with macrocognitive activities in ways that are relevant to cognitive engineering. Previous research using GOMS in sociotechnical systems indicated that GOMS is problematic to use when interruptions and task switching are common; therefore, we added new theoretical structures to GOMS to deal with these issues. We tested the system by constructing a model of routine network maintenance and installation at a large telecommunications company. We then compared the model predictions with observations of the work. The results showed that the model results were useful in guiding the research and organizing the findings.
Fusion of Visual and Auditory Stimuli during Saccades: A Bayesian Explanation for Perisaccadic Distortions
Authors: Binda Paola , Bruno Aurelio , Burr David C. , Morrone Maria C.
Published: August 2007

Brief stimuli presented near the onset of saccades are grossly mislocalized in space. In this study, we investigated whether the Bayesian hypothesis of optimal sensory fusion could account for the mislocalization. We required subjects to localize visual, auditory, and audiovisual stimuli at the time of saccades (compared with an earlier presented target). During fixation, vision dominates and spatially “captures” the auditory stimulus (the ventriloquist effect). But for perisaccadic presentations, auditory localization becomes more important, so the mislocalized visual stimulus is seen closer to its veridical position. The precision of the bimodal localization (as measured by localization thresholds or just-noticeable difference) was better than either the visual or acoustic stimulus presented in isolation. Both the perceived position of the bimodal stimuli and the improved precision were well predicted by assuming statistically optimal Bayesian-like combination of visual and auditory signals. Furthermore, the time course of localization was well predicted by the Bayesian approach. We present a detailed model that simulates the time-course data, assuming that perceived position is given by the sum of retinal position and a sluggish noisy eye-position signal, obtained by integrating optimally the output of two populations of neural activity: one centered at the current point of gaze, the other centered at the future point of gaze.
Neurite Degeneration Induced by Heme Deficiency Mediated via Inhibition of NMDA Receptor-Dependent Extracellular Signal-Regulated Kinase 1/2 Activation
Authors: Chernova Tatyana , Steinert Joern R. , Guerin Christopher J. , Nicotera Pierluigi , Forsythe Ian D. , Smith Andrew G.
Published: August 2007

The early stages of many neurodegenerative diseases and age-related degeneration are characterized by neurite damage and compromised synaptic function that precede neuronal cell death. We investigated the signaling mechanisms underlying neurite degeneration using cortical neuron cultures. Inhibition of heme synthesis caused neurite damage, without neuronal death, and was mediated by reduced NMDA receptor (NMDAR) expression and phosphorylation. The signaling toward the degenerative phenotype involved suppression of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, and electrophysiological recording showed that the neurodegeneration is accompanied by reduced NMDAR current and Ca2+influx, as well as reduced voltage-gated sodium currents, consistent with compromised neurite integrity. Rescue from the degenerative phenotype by heme replacement was dependent on restoration of NR2B subunit phosphorylation and expression of NMDAR currents with higher Ca2+permeability, consistent with triggering prosurvival ERK1/2 signaling to maintain and extend neurites. This study demonstrated a new mechanism of neurodegeneration in which impaired heme synthesis led to NMDAR signaling dysfunction, suppression of the prosurvival ERK1/2 pathway, and progressive fragmentation of neuronal projections.
Effects of Alzheimer's Disease on Different Cortical Layers: The Role of Intrinsic Differences in Aβ Susceptibility
Authors: Romito-DiGiacomo Rita R. , Menegay Harry , Cicero Samantha A. , Herrup Karl
Published: August 2007

Alzheimer's disease is late life dementia associated with significant neurodegeneration in both cortical and subcortical regions. During the ∼10 year course of the disease, neurons are lost in a progressive pattern that is relatively consistent among individuals. One example of this is the progression of disease pathology found in both the neocortex and archicortex. In these structures, the earliest problems can be found in superficial cortical layers (II–IV), whereas later the disease advances to involve the deeper cortical layers (V–VI). It is unclear whether these apparent differences in sensitivity are intrinsic to the neurons or imposed by external factors such as the pattern of connections. We used β-amyloid (Aβ) peptide treatment of cultured mouse neurons as our model system. We show first that, as in hippocampus, dissociated cultures of embryonic cortical neurons are biased toward the survival of cells that were finishing division in the ventricular zone at the time of harvest. Thus, embryonic day 13.5 (E13.5) cultures contain primarily deep-layer neurons whereas E16.5 cultures contain cells destined for upper layers. We use this cell-type specific segregation to our advantage and show, using both differences in gene expression profiles and Aβ survival curves, that deeper layer neurons are significantly more resistant to the toxic effects of Aβ than are cells from the more superficial strata. This suggests that an intrinsic underlying biology drives at least part of the AD progression pattern and that the time of harvest is a crucial variable in the interpretation of any cortical culture experiment.
Dendritic HCN2 Channels Constrain Glutamate-Driven Excitability in Reticular Thalamic Neurons
Authors: Ying Shui-Wang , Jia Fan , Abbas Syed Y. , Hofmann Franz , Ludwig Andreas , Goldstein Peter A.
Published: August 2007

Hyperpolarization activated cyclic nucleotide (HCN) gated channels conduct a current,Ih; howIhinfluences excitability and spike firing depends primarily on channel distribution in subcellular compartments. For example, dendritic expression of HCN1 normalizes somatic voltage responses and spike output in hippocampal and cortical neurons. We reported previously that HCN2 is predominantly expressed in dendritic spines in reticular thalamic nucleus (RTN) neurons, but the functional impact of such nonsomatic HCN2 expression remains unknown. We examined the role of HCN2 expression in regulating RTN excitability and GABAergic output from RTN to thalamocortical relay neurons using wild-type and HCN2 knock-out mice. Pharmacological blockade ofIhsignificantly increased spike firing in RTN neurons and large spontaneous IPSC frequency in relay neurons; conversely, pharmacological enhancement of HCN channel function decreased spontaneous IPSC frequency. HCN2 deletion abolishedIhin RTN neurons and significantly decreased sensitivity to 8-bromo-cAMP and lamotrigine. Recapitulating the effects ofIhblock, HCN2 deletion increased both temporal summation of EPSPs in RTN neurons as well as GABAergic output to postsynaptic relay neurons. The enhanced excitability of RTN neurons afterIhblock required activation of ionotropic glutamate receptors; consistent with this was the colocalization of HCN2 and glutamate receptor 4 subunit immunoreactivities in dendritic spines of RTN neurons. The results indicate that, in mouse RTN neurons, HCN2 is the primary functional isoform underlyingIhand expression of HCN2 constrains excitatory synaptic integration.
The Rodent Lumbar Spinal Cord Learns to Correct Errors in Hindlimb Coordination Caused by Viscous Force Perturbations during Stepping
Authors: Heng Chad , de Leon Ray D.
Published: August 2007

The nervous system can adapt to external forces that perturb locomotion by correcting errors in limb movements. It is believed that supraspinal structures mediate these adaptations, whereas the spinal cord contributes only reflexive responses to perturbations. We examined whether the lumbar spinal cord in postnatal day 5 neonatal spinally transected (ST) rats corrected errors in hindlimb coordination through repetitive exposure to an external perturbation. A robotic device was used to deliver a viscous (velocity-dependent) force that opposed only the forward movement of the ankle in one hindlimb while the ST rats performed hindlimb stepping on a treadmill. We measured the interval between paw contact in the perturbed hindlimb and toe off in the unperturbed hindlimb. Before the force was activated, a normal pattern of coordination occurred: paw contact in the perturbed hindlimb occurred before toe off in the unperturbed hindlimb. This sequence was initially disrupted when the force was activated and the unperturbed hindlimb initiated swing during the swing phase of the perturbed hindlimb. Within five step cycles of exposure to the unilateral viscous force, however, the ST rats regained the preforce pattern of hindlimb coordination. These findings suggest that in the absence of supraspinal input, the lumbar spinal circuitry is capable of processing a complex ensemble of sensory information to maintain locomotor stability. Thus, the lumbar spinal circuitry may play a greater role in generating locomotor adaptations than previously thought.
Role of Calcineurin in Nicotine-Mediated Locomotor Sensitization
Authors: Addy Nii A. , Fornasiero Eugenio F. , Stevens Tanya R. , Taylor Jane R. , Picciotto Marina R.
Published: August 2007

Calcineurin is a serine/threonine phosphatase that contributes to the effects of nicotine on calcium signaling in cultured cortical neurons; however, the role of calcineurin in behavioral responses to nicotinein vivohas not been examined. We therefore determined whether calcineurin blockade could alter nicotine-mediated locomotor sensitization in Sprague Dawley rats using systemic or brain region-specific administration of the calcineurin inhibitors cyclosporine or FK506. Systemic cyclosporine administration decreased calcineurin activity in the brain, attenuated nicotine-mediated locomotor sensitization, and blocked the effects of nicotine on DARPP32 (dopamine- and cAMP-regulated phosphoprotein-32) activation in the striatum. Direct infusion of calcineurin inhibitors cyclosporine or FK506 into the ventral tegmental area (VTA) also attenuated nicotine-mediated locomotor sensitization, whereas infusion of rapamycin, which binds to FK-binding protein but does not inhibit calcineurin, did not affect sensitization. Together, the data suggest that activation of calcineurin, particularly in the VTA, is a novel signaling event important for nicotine-mediated behavior and intracellular signaling.