bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heteroatom‐Substituted Group 4 Bis(indenyl)metallocenes
Authors: Leino Reko , Lehmus Petri , Lehtonen Ari 
Published: August 2004

AbstractThe synthesis, characterization and applications of heteroatom‐substituted group 4 bis(indenyl)metallocene complexes is reviewed. In recent years, an increasing number of group 4 metallocenes with electronically modified cyclopentadienyl ligands have been reported with, in some cases, considerably altered catalytic properties. This microreview focuses on bis(indenyl) complexes of titanium, zirconium and hafnium that contain nitrogen, oxygen and sulfur atoms directly bonded to the five‐ or six‐membered rings of the indenyl ligand framework. The catalytic performance is briefly reviewed, with emphasis on catalytic olefin polymerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Novel Route to Multinuclear d8 Metal−Chalcogen Compounds with Nuclearity Control
Authors: Mas‐Ballesté Rubén , Clegg William , Lledós Agustí , González‐Duarte Pilar 
Published: August 2004

AbstractWe have designed a new synthetic procedure to obtain multinuclear aggregates containing a {Pt2S2}n core. The synthetic strategy involves the reaction of [(dppp)Pt(μ‐S)2Pt(dppp)] with [PtCl2(PhCN)2] and thus the expansion of the {Pt2S2} ring to a [{Pt2S2}PtCl2] fragment. The lability of the chloride anions allows their replacement by bridging sulfide ligands, thus affording a new [{Pt2(μ3‐S)2}{Pt2(μ‐S)2}{Pt2(μ3‐S)2}] core. Its subsequent evolution to [{Pt2S2}3PtCl2] lays the foundation for a new cycle. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
First Tetranuclear CoII Cluster with Planar Triangular Pattern: Crystal Structure and Ferromagnetic Behavior
Authors: Du Miao , Guo Ya‐Mei , Bu Xian‐He , Ribas Joan 
Published: August 2004

AbstractThe preparation, crystal structure and magnetic properties of the first tetrameric CoII cluster with a unique planar triangular motif, [Co4L3(H2O)2](ClO4)2·2H2O (1), based on a carboxylic‐functionalized 1,5‐diazacyclooctane (DACO) bridging ligand [1,5‐bis(2‐carboxyethyl)‐DACO], are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Generation of a conditional allele of the mouse prostaglandin EP4 receptor
Authors: Schneider André , Guan YouFei , Zhang Yahua , Magnuson Mark A. , Pettepher Cathy , Loftin Charles D. , Langenbach Robert , Breyer Richard M. , Breyer Matthew D. 
Published: August 2004

AbstractGenetic disruption of the mouse EP4 receptor results in perinatal lethality associated with persistent patent ductus areteriosus (PDA). To circumvent this, an EP4 allele amenable to conditional deletion using the Cre/loxP system was generated. The targeting construct was comprised of a floxed exon2 in tandem with the neomycin‐resistance gene in intron 2, flanked by third 3′ LoxP site. Mice homozygous for the targeted allele (EP4lox+neo/lox+neo), or following its Cre‐mediated deletion (EP4del/del), also die within hours of birth with PDA. In contrast, mice homozygous for a partially recombined allele, retaining exon2 but lacking neo (EP4flox/flox), are viable and show no overt phenotype. Postnatal deletion of the floxed EP4 gene is efficiently achieved in the liver and kidney in a transgenic mouse expressing the inducible Mx1Cre recombinase. The EP mouse should provide a useful reagent with which to examine the physiologic roles of the EP4 receptor. genesis 40:7–14, 2004. © 2004 Wiley‐Liss, Inc.
Frizzled‐9 promoter drives expression of transgenes in the medial wall of the cortex and its chief derivative the hippocampus
Authors: Zhao Chunjie , Pleasure Samuel J. 
Published: August 2004

AbstractThe hippocampus develops from the medial wall of the forming cerebral cortex during embryonic life. Morphogenic signals from the Wnt pathway regulate several events during hippocampal development (Galceran et al.: Development 127:469–482, 2000; Lee et al.: Development 127:457–467, 2000; Zhou et al.: J Neurosci 24:121–126, 2004) and we have previously shown that Wnt receptors from the Frizzled (Fzd) family are expressed in discreet cortical domains during development (Kim et al.: Mech Dev 103:167–172, 2001). We generated transgenic mice using the putative control elements of the Fzd9 gene, normally selectively expressed in the developing and adult hippocampus, driving expression of a marker gene. These mice express LacZ in the brain in the same developmental distribution as endogenous Fzd protein. Postnatally, expression remains strong in the dendritic fields of hippocampal principal cells as well as hippocampal efferent axons. These mice provide a genetic and anatomic tool for analyzing development and reorganization in the hippocampus. genesis 40:32–39, 2004. © 2004 Wiley‐Liss, Inc.
Comparing alternative models: log vs Cox proportional hazard?
Authors: Basu Anirban , Manning Willard G. , Mullahy John 
Published: August 2004

AbstractHealth economists often use log models (based on OLS or generalized linear models) to deal with skewed outcomes such as those found in health expenditures and inpatient length of stay. Some recent studies have employed Cox proportional hazard regression as a less parametric alternative to OLS and GLM models, even when there was no need to correct for censoring. This study examines how well the alternative estimators behave econometrically in terms of bias when the data are skewed to the right. Specifically we provide evidence on the performance of the Cox model under a variety of data generating mechanisms and compare it to the estimators studied recently in Manning and Mullahy (2001). No single alternative is best under all of the conditions examined here. However, the gamma regression model with a log link seems to be more robust to alternative data generating mechanisms than either OLS on ln(y) or Cox proportional hazards regression. We find that the proportional hazard assumption is an essential requirement to obtain consistent estimate of the E(y∣x) using the Cox model. Copyright © 2004 John Wiley & Sons, Ltd.
The productivity of health care and health production functions
Authors: Koç Çağatay 
Published: August 2004

AbstractThis paper derives a necessary and sufficient condition under which increased health care productivity must lead to decreased (increased) demand for health care as long as the demand for health care is inelastic (elastic). It is shown that this condition identifies a class of health production functions, which may provide useful guidance to empirical studies that depend wholly or partly on the correct specification of a health production function. As an illustration, it is demonstrated that this class of production functions may be useful for empirical studies that test the hypothesis that schooling, increasing the efficiency of health production, leads to a larger health output from a given set of health inputs. The paper also offers broader classes of production functions that would enable one to test this relationship between the demand elasticity and the effect of health care productivity on health care demand. Copyright © 2004 John Wiley & Sons, Ltd.
Assessing quality of life in the elderly: a direct comparison of the EQ‐5D and AQoL
Authors: Holland Richard , Smith Richard D , Harvey Ian , Swift Louise , Lenaghan Elizabeth 
Published: August 2004

AbstractAs more research is undertaken on the elderly, accurately assessing changes in their quality of life becomes increasingly important. Generic instruments are the most popular method to assess quality of life, and one of the most widely used is the EQ‐5D. However, the range of dimensions, sensitivity of scales and completion rates have been raised as concerns when using this measure with the elderly. The AQoL is a newer instrument which offers greater richness in dimensions of health covered, and potentially offers greater sensitivity to changes in quality of life.This paper presents the results of a ‘head‐to‐head’ comparison of the EQ‐5D and AQoL in terms of practicality, construct validity, agreement (of absolute scores and their change over time) and sensitivity to change, as part of a randomised controlled trial in the elderly. Poor agreement was found between both the absolute scores from each instrument and change in scores over time. Although the AQoL appeared to have more favourable construct validity, the EQ‐5D was easier to administer, had a higher completion rate, and appeared more sensitive to change. We conclude that the AQoL is probably less well suited to measuring health status in a very elderly population than the EQ‐5D. Copyright © 2004 John Wiley & Sons, Ltd.
The influence of subjective expectations about length and quality of life on time trade‐off answers
Authors: Nooten Floortje van , Brouwer Werner 
Published: August 2004

AbstractWhen answering TTO questions respondents sometimes have to imagine being in a certain health state during their remaining lifespan, often based on objective life tables. Respondents however may have subjective expectations about length and quality of life that differ from the objective ones. If respondents do not fully abstract from own expectations, TTO scores may be biased. In this note, we indicate how subjective expectations could influence TTO scores and present some empirical findings suggesting that they do. Our results indicate that subjective expectations may serve as unobserved reference points and as such influence TTO responses. Copyright © 2004 John Wiley & Sons, Ltd.
Characterizing fibroblast migration on discrete collagen threads for applications in tissue regeneration
Authors: Cornwell Kevin G. , Downing Brett R. , Pins George D. 
Published: August 2004

AbstractCollagen threads with mechanical properties and fibrillar substructure similar to native tissue have been synthesized for the repair of injured tendon and ligament. While these scaffolding materials have demonstrated the potential for inducing tissue regeneration, one limitation has been an insufficient rate of tissue ingrowth for complete regeneration. We hypothesize that the structural hierarchy and biochemical cues on the surfaces of these threads will enhance the rate of cell migration and ultimately the rate of new tissue ingrowth. We developed an in vitro assay to measure the effects of various collagen sources and crosslinking on the rate of fibroblast migration on the surfaces of collagen threads. Threads were suspended from elevated platforms and seeded with fibroblast‐populated collagen lattices. Cell migration rates ranging from 0.75 to 1.25 mm/day were measured as the fibroblasts left the lattices and migrated onto various thread types. Threads self‐assembled from type I collagen were found to have migration rates similar to native tendon threads while crosslinking by severe dehydration decreased the rate. This novel in vitro model system allows examination of cell migration from a wound margin onto biomaterials to determine the effects of various cell types, matrix materials, and surface biochemistries on cell–matrix interactions. Ultimately, this assay will allow us to identify design parameters that will be most effective for enhancing the rate of tissue ingrowth on fiber‐based collagen scaffolds for soft tissue regeneration. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 55–62, 2004
Penetration depth into dental casting alloys by Nd:YAG laser
Authors: Baba N. , Watanabe I. 
Published: August 2004

AbstractThis study investigated the effect of laser‐beam welding conditions [voltage (V) and spot diameter (mm)] on the penetration depth into dental casting alloys. Castings (3.0 mm × 8.0 mm × 50 mm) were prepared from the metals used in this study: commercially pure titanium (CP Ti), Ti‐6Al‐4V, Ti‐6Al‐7Nb, cobalt–chromium alloy (Co–Cr) and Type IV gold alloy. Two cast blocks of each metal were butted against one another at the 8.0 × 50‐mm surfaces. They were then welded at their interface under the following conditions: voltage of 160–340 V, spot diameter of 0.4–1.6 mm, and pulse duration of 10 ms. After laser welding, the blocks were separated, and the penetration depth into each alloy was measured. The data were analyzed with the use of ANOVA at the p < 0.05 level of significance. The penetration depths were as follows: CP Ti (0.29–6.45 mm), Ti‐6Al‐4V (0.32–5.24 mm), Ti‐6Al‐7Nb (0.34–5.65 mm), Co–Cr (0.24–6.15 mm), and Type IV gold alloy (0.12–5.22 mm). The voltage and spot diameter affected the penetration depth into the metals tested. When the voltage increased and the spot diameter decreased, the penetration depth increased for each metal. Selecting suitable conditions for laser welding to obtain sufficient penetration depth for the optimal thickness of the metal is important when welding prostheses. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 64–68, 2005
Proinflammatory mediator expression in a novel murine model of titanium‐particle–induced intramedullary inflammation
Authors: Warme Bryan A. , Epstein Noah J. , Trindade Michael C. D. , Miyanishi Keita , Ma Ting , Saket Ramin R. , Regula Donald , Goodman Stuart B. , Smith R. Lane 
Published: August 2004

AbstractWear debris from total joint replacement prostheses is implicated in periprosthetic osteolysis and implant loosening. The pathophysiology of this biological process remains unclear. Animal models of particle‐induced osteolysis have proven useful in the study of specific tissue responses to wear debris. However, existing in vivo murine models of particle‐mediated inflammation do not permit analysis of cortical bone degradation. This study describes a murine model of particle disease using an intramedullary rod in the mouse femur to parallel the clinical situation. The model consists of placing a 10‐mm‐long Kirschner wire retrograde in both femurs of C57b1/6 male mice via a medial parapatellar arthrotomy. Phagocytosable titanium particles were also implanted unilaterally to replicate generation of wear debris. Mice were sacrificed at 2, 10, and 26 weeks and whole femurs were cultured for 72 h. Levels of interleukin‐6, monocyte chemotactic protein‐1, and macrophage colony stimulating factor were assayed by ELISA. Transverse histological sections, at the level of the implant, were taken and stained with hematoxylin and eosin (H&E). Results demonstrated increased expression of proinflammatory mediators at 2 weeks in femora with rod and particles compared to femora with rods alone. Destruction of the endosteum was evident at 2, 10, and 26 weeks in the femora with titanium. This novel murine model of particle‐induced intramedullary inflammation may facilitate cost‐effective genetic studies and offers investigators a simple, clinically relevant intramedullary model to readily examine the pathogenesis of particle‐mediated periprosthetic osteolysis. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 360–366, 2004
Protein kinases and adherens junction dynamics in the seminiferous epithelium of the rat testis
Authors: Lee Nikki P.Y. , Cheng C. Yan 
Published: August 2004

AbstractEarlier studies in multiple epithelia have shown that cell–cell actin‐based adherens junction (AJ) dynamics are regulated, at least in part, by the interplay of kinases and phosphatases that determines the intracellular phosphoprotein content. Yet it is virtually unknown regarding the role of protein kinases in Sertoli–germ cell AJ dynamics in the seminiferous epithelium of the testis. To address this issue, an in vitro coculture system utilizing Sertoli and germ cells was used to study the regulation of several protein kinases, including c‐Src (the cellular form of the v‐src transforming gene of Rous Sarcoma virus, RSV), carboxyl‐terminal Src kinase (Csk), and casein kinase 2 (CK2), during AJ assembly. Both Sertoli and germ cells were shown to express c‐Src, Csk, and CK2 with a relative Sertoli:germ cell ratio of ∼1:1, suggesting both cell types contributed equally to the pool of these kinases in the epithelium. c‐Src and Csk were shown to be stage‐specific proteins during the epithelial cycle, being highest at stages VII–VIII. Studies using immunoprecipitation have illustrated that these kinases were structurally associated with the N‐cadherin/β‐catenin, but not the nectin/afadin, protein complex, implicating that the cadherin/catenin protein complex is their likely putative substrate. An induction in c‐Src, Csk, and CK2 were detected during Sertoli–germ cell AJ assembly in vitro but not when Sertoli cells were cultured alone. When adult rats were treated with 1‐(2,4‐dichlorobenzyl)‐indazole‐3‐carbohydrazide (AF‐2364), a compound known to induce germ cell loss from the seminiferous epithelium, in particular elongating/elongate and round spermatids, by disrupting Sertoli–germ cell AJs, an induction of c‐Src and Csk, but not CK2, was detected. Furthermore, a transient increase in the intrinsic kinase activities of c‐Src, but not CK2, was also detected. This event was also associated with a loss of protein–protein association of N‐cadherin and β‐catenin from the cadherin/catenin/c‐Src/Csk/CK2 protein complex. Administration of PP1, a c‐Src inhibitor, into adult rats via the jugular vein could induce the loss of spermatocytes and round spermatids, but not elongating/elongate spermatids, from the seminiferous epithelium. This result thus implicates the importance of c‐Src in maintaining the integrity of AJs and possibly desmosome‐like junctions between Sertoli cells and spermatocytes/round spermatids. In short, the data reported herein have shown that c‐Src, Csk, and CK2 are novel protein kinases in AJ dynamics in the testis. © 2004 Wiley‐Liss, Inc.
Alpha‐interferon and its effects on signal transduction pathways
Authors: Caraglia Michele , Marra Monica , Pelaia Girolamo , Maselli Rosario , Caputi Mario , Marsico Serafino A. , Abbruzzese Alberto 
Published: August 2004

AbstractInterferon‐α (IFNα) is a recombinant protein widely used in the therapy of several neoplasms such as myeloma, renal cell carcinoma, epidermoid cervical and head and neck tumors, and melanoma. IFNα, the first cytokine to be produced by recombinant DNA technology, has emerged as an important regulator of cancer cell growth and differentiation, affecting cellular communication and signal transduction pathways. However, the way by which tumor cell growth is directly suppressed by IFNα is not well known. Wide evidence exists on the possibility that cancer cells undergo apoptosis after the exposure to the cytokine. Here we will review the consolidate signal transducer and activator of transcription (STAT)‐dependent mechanism of action of IFNα. We will discuss data obtained by us and others on the triggering of the stress‐dependent kinase pathway induced by IFNα and its correlations with the apoptotic process. The regulation of the expression of proteins involved in apoptosis occurrence will be also described. In this regard, IFNα is emerging as a post‐translational controller of the intracellular levels of the apoptosis‐related protein tissue transglutaminase (tTG). This new way of regulation of tTG occurs through the modulation of their proteasome‐dependent degradation induced by the cytokine. Until today, inconsistent data have been obtained regarding the clinical effectiveness of IFNα in the therapy of solid tumors. In fact, the benefit of IFNα treatment is limited to some neoplasms while others are completely or partially resistant. The mechanisms of tumor resistance to IFNα have been studied in vitro. The alteration of JAK‐STAT components of the IFNα‐induced signaling, can be indeed a mechanism of resistance to IFN. However, we have recently described a reactive mechanism of protection of tumor cells from the apoptosis induced by IFNα dependent on the epidermal growth factor (EGF)‐mediated Ras/extracellular signal regulated kinase (Erk) signaling. The involvement of the Ras→Erk pathway in the protection of tumor cells from the apoptosis induced by IFNα is further demonstrated by both Ras inactivation by RASN17 transfection and mitogen extracellular signal regulated kinase 1 (Mek‐1) inhibition by exposure to PD098059. These data strongly suggest that the specific disruption of the latter could be a useful approach to potentiate the antitumour activity of IFNα against human tumors based on the new mechanistic insights achieved in the last years. © 2004 Wiley‐Liss, Inc.
Neurogenesis in the subventricular zone following transcranial magnetic field stimulation and nigrostriatal lesions
Authors: Arias‐Carrión O. , Verdugo‐Díaz L. , Feria‐Velasco A. , Millán‐Aldaco D. , Gutiérrez A.A. , Hernández‐Cruz A. , Drucker‐Colín R. 
Published: August 2004

AbstractNeurogenesis continues at least in two regions of the mammalian adult brain, the subventricular zone (SVZ) and the subgranular zone in hippocampal dentate gyrus. Neurogenesis in these regions is subjected to physiological regulation and can be modified by pharmacological and pathological events. Here we report the induction of neurogenesis in the SVZ and the differentiation after nigrostriatal pathway lesion along with transcranial magnetic field stimulation (TMFS) in adult rats. Significant numbers of proliferating cells demonstrated by bromodeoxyuridine‐positive reaction colocalized with the neuronal marker NeuN were detected bilaterally in the SVZ, and several of these cells also expressed tyrosine hydroxylase. Transplanted chromaffin cells into lesioned animals also induced bilateral appearance of subependymal cells. These results show for the first time that unilateral lesion, transplant, and/or TMFS induce neurogenesis in the SVZ of rats and also that TMFS prevents the motor alterations induced by the lesion. © 2004 Wiley‐Liss, Inc.
Thermally Produced Biodegradable Scaffolds for Cartilage Tissue Engineering
Authors: Lee Soo‐Hong , Kim Byung‐Soo , Kim Soo Hyun , Kang Sun Woong , Kim Young Ha 
Published: August 2004

AbstractSummary: A novel process was developed to fabricate biodegradable polymer scaffolds for tissue engineering applications, without using organic solvents. Solvent residues in scaffolds fabricated by processes involving organic solvents may damage cells transplanted onto the scaffolds or tissue near the transplantation site. Poly(L‐lactic acid) (PLLA) powder and NaCl particles in a mold were compressed and subsequently heated at 180 °C (near the PLLA melting temperature) for 3 min. The heat treatment caused the polymer particles to fuse and form a continuous matrix containing entrapped NaCl particles. After dissolving the NaCl salts, which served as a porogen, porous biodegradable PLLA scaffolds were formed. The scaffold porosity and pore size were controlled by adjusting the NaCl/PLLA weight ratio and the NaCl particle size. The characteristics of the scaffolds were compared to those of scaffolds fabricated using a conventional solvent casting/particulate leaching (SC/PL) process, in terms of pore structure, pore‐size distribution, and mechanical properties. A scanning electron microscopic examination showed highly interconnected and open pore structures in the scaffolds fabricated using the thermal process, whereas the SC/PL process yielded scaffolds with less interconnected and closed pore structures. Mercury intrusion porosimetry revealed that the thermally produced scaffolds had a much more uniform distribution of pore sizes than the SC/PL process. The utility of the thermally produced scaffolds was demonstrated by engineering cartilaginous tissues in vivo. In summary, the thermal process developed in this study yields tissue‐engineering scaffolds with more favorable characteristics, with respect to, freedom from organic solvents, pore structure, and size distribution than the SC/PL process. Moreover, the thermal process could also be used to fabricate scaffolds from polymers that are insoluble in organic solvents, such as poly(glycolic acid).Cartilage tissue regenerated from thermally produced PLLA scaffold.magnified imageCartilage tissue regenerated from thermally produced PLLA scaffold.