bluuebunny/crossref_metadata_2025_split huggingface dataset:
The myeloproliferative disorder–associated JAK2 V617F mutant escapes negative regulation by suppressor of cytokine signaling 3
Authors: Hookham Michelle B. , Elliott Joanne , Suessmuth Yvonne , Staerk Judith , Ward Alister C. , Vainchenker William , Percy Melanie J. , McMullin Mary Frances , Constantinescu Stefan N. , Johnston James A. 
Published: February 2007

Abstract
The somatic JAK2 valine-to-phenylalanine (V617F) mutation has been detected in up to 90% of patients with polycythemia and in a sizeable proportion of patients with other myeloproliferative disorders such as essential thrombocythemia and idiopathic myelofibrosis. Suppressor of cytokine signaling 3 (SOCS3) is known to be a strong negative regulator of erythropoietin (EPO) signaling through interaction with both the EPO receptor (EPOR) and JAK2. We report here that JAK2 V617F cannot be regulated and that its activation is actually potentiated in the presence of SOCS3. Instead of acting as a suppressor, SOCS3 enhanced the proliferation of cells expressing both JAK2 V617F and EPOR. Additionally, although SOCS1 and SOCS2 are degraded in the presence of JAK2 V617F, turnover of SOCS3 is inhibited by the JAK2 mutant kinase and this correlated with marked tyrosine phosphorylation of SOCS3 protein. We also observed constitutive tyrosine phosphorylation of SOCS3 in peripheral blood mononuclear cells (PBMCs) derived from patients homozygous for the JAK2 V617F mutant. These findings suggest that the JAK2 V617F has overcome normal SOCS regulation by hyperphosphorylating SOCS3, rendering it unable to inhibit the mutant kinase. Thus, JAK2 V617F may even exploit SOCS3 to potentiate its myeloproliferative capacity.
Cyclin D–Cdk4 is regulated by GATA-1 and required for megakaryocyte growth and polyploidization
Authors: Muntean Andrew G. , Pang Liyan , Poncz Mortimer , Dowdy Steven F. , Blobel Gerd A. , Crispino John D. 
Published: February 2007

Abstract
Endomitosis is a unique form of cell cycle used by megakaryocytes, in which the latter stages of mitosis are bypassed so that the cell can increase its DNA content and size. Although several transcription factors, including GATA-1 and RUNX-1, have been implicated in this process, the link between transcription factors and polyploidization remains undefined. Here we show that GATA-1–deficient megakaryocytes, which display reduced size and polyploidization, express nearly 10-fold less cyclin D1 and 10-fold increased levels of p16 compared with their wild-type counterparts. We further demonstrate that cyclin D1 is a direct GATA-1 target in megakaryocytes, but not erythroid cells. Restoration of cyclin D1 expression, when accompanied by ectopic overexpression of its partner Cdk4, resulted in a dramatic increase in megakaryocyte size and DNA content. However, terminal differentiation was not rescued. Of note, polyploidization was only modestly reduced in cyclin D1–deficient mice, likely due to compensation by elevated cyclin D3 expression. Finally, consistent with an additional defect conferred by increased levels of p16, inhibition of cyclin D-Cdk4 complexes with a TAT-p16 fusion peptide significantly blocked polyploidization of wild-type megakaryocytes. Together, these data show that GATA-1 controls growth and polyploidization by regulating cyclin D-Cdk4 kinase activity.
Missing KIR ligands are associated with less relapse and increased graft-versus-host disease (GVHD) following unrelated donor allogeneic HCT
Authors: Miller Jeffery S. , Cooley Sarah , Parham Peter , Farag Sherif S. , Verneris Michael R. , McQueen Karina L. , Guethlein Lisbeth A. , Trachtenberg Elizabeth A. , Haagenson Michael , Horowitz Mary M. , Klein John P. , Weisdorf Daniel J. 
Published: February 2007

Abstract
Natural killer (NK) cells can alter the outcome of hematopoietic cell transplantation (HCT) if donor alloreactivity targets the recipient. Since most NK cells express inhibitory killer-immunoglobulin receptors (KIRs), we hypothesized that the susceptibility of recipient cells to donor NK cell–mediated lysis is genetically predetermined by the absence of known KIR ligands. We analyzed data from 2062 patients undergoing unrelated donor HCT for acute myeloid leukemia (AML; n = 556), chronic myeloid leukemia (CML; n = 1224), and myelodysplastic syndrome (MDS; n = 282). Missing 1 or more KIR ligands versus the presence of all ligands protected against relapse in patients with early myeloid leukemia (relative risk [RR] = 0.54; n = 536, 95% confidence interval [CI] 0.30-0.95, P = .03). In the subset of CML patients that received a transplant beyond 1 year from diagnosis (n = 479), missing a KIR ligand independently predicted a greater risk of developing grade 3-4 acute graft-versus-host disease (GVHD; RR = 1.58, 95% CI 1.13-2.22; P = .008). These data support a genetically determined role for NK cells following unrelated HCT in myeloid leukemia.
Distinct mechanisms of loss of IFN-gamma mediated HLA class I inducibility in two melanoma cell lines
Authors: Rodríguez Teresa , Méndez Rosa , Del Campo Ana , Jiménez Pilar , Aptsiauri Natalia , Garrido Federico , Ruiz-Cabello Francisco 
Published: February 2007

AbstractBackgroundThe inability of cancer cells to present antigen on the cell surface via MHC class I molecules is one of the mechanisms by which tumor cells evade anti-tumor immunity. Alterations of Jak-STAT components of interferon (IFN)-mediated signaling can contribute to the mechanism of cell resistance to IFN, leading to lack of MHC class I inducibility. Hence, the identification of IFN-γ-resistant tumors may have prognostic and/or therapeutic relevance. In the present study, we investigated a mechanism of MHC class I inducibility in response to IFN-γ treatment in human melanoma cell lines.MethodsBasal and IFN-induced expression of HLA class I antigens was analyzed by means of indirect immunofluorescence flow cytometry, Western Blot, RT-PCR, and quantitative real-time RT-PCR (TaqMan®Gene Expression Assays). In demethylation studies cells were cultured with 5-aza-2'-deoxycytidine. Electrophoretic Mobility Shift Assay (EMSA) was used to assay whether IRF-1 promoter binding activity is induced in IFN-γ-treated cells.ResultsAltered IFN-γ mediated HLA-class I induction was observed in two melanoma cells lines (ESTDAB-004 and ESTDAB-159) out of 57 studied, while treatment of these two cell lines with IFN-α led to normal induction of HLA class I antigen expression. Examination of STAT-1 in ESTDAB-004 after IFN-γ treatment demonstrated that the STAT-1 protein was expressed but not phosphorylated. Interestingly, IFN-α treatment induced normal STAT-1 phosphorylation and HLA class I expression. In contrast, the absence of response to IFN-γ in ESTDAB-159 was found to be associated with alterations in downstream components of the IFN-γ signaling pathway.ConclusionWe observed two distinct mechanisms of loss of IFN-γ inducibility of HLA class I antigens in two melanoma cell lines. Our findings suggest that loss of HLA class I induction in ESTDAB-004 cells results from a defect in the earliest steps of the IFN-γ signaling pathway due to absence of STAT-1 tyrosine-phosphorylation, while absence of IFN-γ-mediated HLA class I expression in ESTDAB-159 cells is due to epigenetic blocking of IFN-regulatory factor 1 (IRF-1) transactivation.
A novel method for the evaluation of proximal tubule epithelial cellular necrosis in the intact rat kidney using ethidium homodimer
Authors: Edwards Joshua R , Diamantakos Evangelos A , Peuler Jacob D , Lamar Peter C , Prozialeck Walter C 
Published: February 2007

Abstract

Background
Ethidium homodimer is a cell-membrane impermeant nuclear fluorochrome that has been widely used to identify necrotic cells in culture. Here, we describe a novel technique for evaluating necrosis of epithelial cells in the proximal tubule that involves perfusing ethidium homodimer through the intact rat kidney. As a positive control for inducing necrosis, rats were treated with 3.5, 1.75, 0.87 and 0.43 mg/kg mercuric chloride (Hg2+, intraperitoneal), treatments which have previously been shown to rapidly cause dose-dependent necrosis of the proximal tubule. Twenty-four h after the administration of Hg2+, ethidium homodimer (5 μM) was perfused through the intact left kidney while the animal was anesthetized. The kidney was then removed, placed in embedding medium, frozen and cryosectioned at a thickness of 5 μm. Sections were permeabilized with -20°C methanol and then stained with 4',6-diamidino-2-phenylindole (DAPI) to label total nuclei. Total cell number was determined from the DAPI staining in random microscopic fields and the number of necrotic cells in the same field was determined by ethidium homodimer labeling.

Results
The Hg2+-treated animals showed a dose-dependent increase in the number of ethidium labeled cells in the proximal tubule, but not in other segments of the nephron. Other results showed that a nephrotoxic dose of gentamicin also caused a significant increase in the number of ethidium labeled cells in the proximal tubule.

Conclusion
These results indicate that this simple and sensitive perfusion technique can be used to evaluate cellular necrosis in the proximal tubule with the three-dimensional cyto-architecture intact.
Do beliefs about HIV treatments affect peer norms and risky sexual behaviour among African-American men who have sex with men?
Authors: Bakeman Roger , Peterson John L ,   The Community Intervention Trial for Youth Study Team
Published: February 2007

We examined the association between perceptions about condom use among one's peers, beliefs about new HIV treatments, and HIV sexual risk behaviour among 849 young African-American men who have sex with men (MSM). Participants were randomly recruited from and anonymously interviewed in community venues in Atlanta, Georgia, USA, in cross-sectional samples between 1999 and 2002. Data analyses indicated that 30% of the sample reported unprotected anal intercourse in the past three months; stronger peer condom norms predicted less-frequent risky sexual behaviour. However, the belief in less threat of HIV because of HIV treatments was not associated with either risky sexual behaviour or peer norms, and peer norms did not mediate the association between HIV treatment beliefs and unprotected anal intercourse. These findings suggest that changing peer norms for condom use may reduce HIV risky sex in African-American MSM, regardless of their beliefs about HIV drug treatments.
Testing a Life-Cycle Theory of Cooperative Interorganizational Relationships: Movement Across Stages and Performance
Authors: Jap Sandy D. , Anderson Erin 
Published: February 2007

This research examines the evolution of cooperative interorganizational relationships and provides an empirical test of four propositions from the DSO (Dwyer et al. 1987) life-cycle theory, and one proposition from the RV (Ring and Van de Ven 1994) theory of relationship development. Using primary data from over 1,500 resellers in a channel of distribution, we find that the mature phase is not the pinnacle of the relationship lifecycle; relationship properties (e.g., relationship harmony, overall dependence, and the reseller’s trust in the manufacturer) in this stage are no different than in the build-up phase. However, relationship properties that support relationship expansion (e.g., goal congruence and information exchange norms) reach their zenith in the build-up phase and afterwards fade into the background. All of the various relationship properties hit their nadir in the decline phase.We also examine the development of relationships over a five-year period and consider whether movement across the stages in accordance with DSO’s theory has the same association to overall performance evaluations as movement through regressive patterns. We find that a negative history extracts a price: Movement through regressive patterns is negatively related to performance, and these relationships do not enjoy a fresh start. Instead, these movements can last for an extended period of time and are negatively related to performance outcomes during the decline phase. Thus, the development path taken appears to be related to the results achieved. Finally, we also find evidence of the critical role that individual sales representatives play in creating successful interorganizational relationships.
Strategic Technology Choice and Capacity Investment Under Demand Uncertainty
Authors: Goyal Manu , Netessine Serguei 
Published: February 2007

This paper studies the impact of competition on a firm’s choice of technology (product-flexible or product-dedicated) and capacity investment decisions. Specifically, we model two firms competing with each other in two markets characterized by price-dependent and uncertain demand. The firms make three decisions in the following sequence: choice of technology (technology game), capacity investment (capacity game), and production quantities (production game). The technology and capacity games occur while the demand curve is still uncertain, and the production game is postponed until after the demand curve is revealed. We develop best-response functions for each firm in the technology game and compare how a monopolist and a duopolist respond to a given flexibility premium. We show that the firms may respond to competition by adopting a technology which is the same as or different from what the competitor adopts. We conclude that contrary to popular belief, flexibility is not always the best response to competition—flexible and dedicated technologies may coexist in equilibrium. We demonstrate that as the difference between the two market sizes increases, a duopolist is willing to pay less for flexible technology, whereas the decision of a monopolist is not affected. Further, we find that a firm that invests in flexibility benefits from a low correlation between demands for two products, but the extent of this benefit differs depending on the competitor’s technology choice. Our results indicate that higher demand substitution may or may not promote the adoption of flexibility under competition, whereas it always facilitates the adoption of flexibility without competition. Finally, we show that contrary to intuition, as the competitor’s cost of capacity increases, the premium a flexible firm is willing to pay for flexibility decreases.
An introduction to the Rasch measurement model: An example using the Hospital Anxiety and Depression Scale (HADS)
Authors: Pallant Julie F. , Tennant Alan 
Published: February 2007

Objectives To demonstrate the use of Rasch analysis by assessing the appropriateness of utilizing the Hospital Anxiety and Depression Scale (HADS) total score (HADS‐14) as a measure of psychological distress.Design Cross‐sectional, using Rasch analysis.Methods The HADS was administered to 296 patients attending an out‐patient musculoskeletal rehabilitation program. Rasch analysis was conducted using RUMM2020 software to assess the overall fit of the model, the response scale used, individual item fit, differential item functioning (DIF) and person separation.Results Rasch analysis supported the viability of the HADS‐14 as a measure of psychological distress. It showed good person separation, little disordering of the thresholds and no evidence of DIF. One anxiety item (item 11) showed some misfit to the model. The residuals patterned into the two subscales (anxiety and depression), but the person estimate derived from these two subscales was not statistically different to that derived from all items taken together, supporting the assumption of unidimensionality. A cut‐point of 12 on the HADS‐14 identified all cases that were classified as both anxious and depressed on the original individual HADS subscales.Conclusions The results of Rasch analysis support the use of the HADS‐14 as a global measure of psychological distress. The study demonstrates the usefulness of Rasch analysis in assessing the psychometric properties of a scale and suggests that further use of this technique to assess the HADS‐14 in other clinical groups is warranted.
Mutant-Enriched PCR and Allele-Specific Hybridization Reaction to Detect K-ras Mutations in Stool DNA: High Prevalence in a Large Sample of Older Adults
Authors: Haug Ulrike , Hillebrand Timo , Bendzko Peter , Löw Michael , Rothenbacher Dietrich , Stegmaier Christa , Brenner Hermann 
Published: February 2007

Abstract
Background: Testing for mutant K-ras in stool has been proposed for the detection of pancreatic and colorectal cancer (CRC). Different analytical techniques have been developed, but studies of this biomarker in the general population are lacking. We investigated the prevalence and potential determinants of mutant K-ras in stool in a large sample of unselected older adults and assessed the association with colonoscopic findings.
Methods: In stool samples from 875 older adults (age range 50–75 years) participating in a large-scale population-based cohort study, we used mutant-enriched PCR and allele-specific hybridization reaction to analyze mutations in codons 12 and 13 of the K-ras gene. We assessed the association between mutant K-ras in stool and risk factors for gastrointestinal cancer sites, exocrine pancreatic insufficiency determined by fecal pancreas elastase 1, and colonoscopic findings.
Results: The overall prevalence of mutant K-ras in stool was 8% (95% confidence interval 6%–10%). There was a tentative association between increased fecal pancreas elastase 1 and mutant K-ras in stool (P = 0.09). Patients with advanced colorectal neoplasia diagnosed within 2 years after stool collection (24 with advanced adenomas, 7 with CRC) all tested negative.
Conclusion: The proposed assay identifies mutant K-ras in stool at a higher prevalence than has been reported for other analytical techniques. Our findings do not support the use of this assay for CRC screening, but its potential use for early detection of pancreatic cancer (in combination with other markers) requires further investigation.
Pharmacodynamic Target Attainment of Six β‐Lactams and Two Fluoroquinolones Against Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, and Klebsiella Species Collected from United States Intensive Care Units in 2004
Authors: DeRyke C. Andrew , Kuti Joseph L. , Nicolau David P. 
Published: February 2007

Study Objective. To determine the likelihood that antibiotic regimens achieve bactericidal pharmacodynamic exposures against common nosocomial pathogens.Design. Pharmacodynamic Monte Carlo simulation model.Data Source. Microbiologic data generated from isolates from the 14 centers in the United States in the 2004 Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) surveillance study.Patients. Five thousand simulated patients with infection.Measurements and Main Results. Pharmacokinetic profiles of the patients were simulated to determine the bactericidal cumulative fraction of response (CFR) for commonly used intravenous regimens of cefepime, ceftazidime, ceftriaxone, ciprofloxacin, imipenem, levofloxacin, meropenem, and piperacillin‐tazobactam against Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, and Klebsiella species. Ciprofloxacin and levofloxacin had CFRs among the lowest of all drugs against all pathogens, especially P. aeruginosa (40.4–65.5%) and A. baumannii (43.6–48.2%). The low CFR of about 78% against E. coli with these two agents was of particular concern. Among the β‐lactams, only high‐dose cefepime and ceftazidime regimens achieved CFRs of greater than 90% against P. aeruginosa, followed by cefepime 2 g every 12 hours and the carbapenems (86.3–89.7%). No regimen achieved an optimum CFR for A. baumannii. All β‐lactam regimens achieved a greater‐than‐90% likelihood of having bactericidal CFRs against Enterobacteriaceae.Conclusion. Because of the continual evolution of resistance among gram‐negative bacteria in the United States, reevaluation of optimum dosing strategies for β‐lactam and fluoroquinolone antibiotics is necessary.
Comparison of Oxidative Stress Markers After Intravenous Administration of Iron Dextran, Sodium Ferric Gluconate, and Iron Sucrose in Patients Undergoing Hemodialysis
Authors: Pai Amy Barton , Boyd Alex V. , McQuade Charles R. , Harford Antonia , Norenberg Jeffrey P. , Zager Philip G. 
Published: February 2007

Study Objective. To compare non–transferrin‐bound iron and markers of oxidative stress after single intravenous doses of iron dextran, sodium ferric gluconate, and iron sucrose.Design. Prospective, open‐label, crossover study.Setting. University‐affiliated general clinical research center.Patients. Twelve ambulatory patients undergoing hemodialysis.Intervention. Patients received 100 mg of intravenous iron dextran, sodium ferric gluconate, and iron sucrose in random sequence, with a 2‐week washout period between treatments.Measurements and Main Results. Serum samples for transferrin saturation, non–transferrin‐bound iron, and malondialdehyde (MDA; marker of lipid peroxidation) were obtained before (baseline) and 30, 60, 120, and 360 minutes and 2 weeks after each iron infusion. A serum sample for hemeoxygenase‐1 (HO‐1) RNA was obtained at baseline and 360 minutes after infusion. Non–transferrin‐bound iron values were significantly higher 30 minutes after administration of sodium ferric gluconate and iron sucrose compared with iron dextran (mean ± SEM 10.1 ± 2.2, 3.8 ± 0.8, and 0.23 ± 0.1 μM, respectively, p<0.001 for sodium ferric gluconate vs iron dextran, p=0.002 for iron sucrose vs iron dextran). A significant positive correlation was noted between transferrin saturation and the presence of non–trans‐ferrin‐bound iron for sodium ferric gluconate and iron sucrose (r2=0.37 and 0.45, respectively, p<0.001) but not for iron dextran (r2= 0.09). After sodium ferric gluconate, significantly more samples showed increases in MDA levels from baseline compared with iron sucrose and iron dextran (p=0.006); these increased levels were associated with the presence of non–transferrin‐bound iron, baseline transferrin saturation above 30%, baseline transferrin levels below 180 mg/dl, and ferritin levels above 500 ng/ml (p<0.05). However, only a transferrin level below 180 mg/dl was independently associated (odds ratio 4.8, 95% confidence interval 1.2–15.3).Conclusion. Iron sucrose and sodium ferric gluconate were associated with greater non–transferrin‐bound iron appearance compared with iron dextran. However, only sodium ferric gluconate showed significant increases in lipid peroxidation. The relationship between non–transferrin‐bound iron from intravenous iron and oxidative stress warrants further exploration.