bluuebunny/crossref_metadata_2025 huggingface dataset:
The porosity dependence of the dielectric constant for sintered hydroxyapatite
Authors: Hoepfner Timothy P. , Case Eldon D.
Published: August 2002

Hydroxyapatite (HAp) is the major mineral constituent of bone, and as such, the dielectric properties of HAp are of interest because electromagnetic fields have been shown to accelerate healing in bone fractures. In addition, an interest in the dielectric properties of HAp stems from the suggestion that electrically insulating HAp coatings might be used on implantable devices. In this study, the dielectric constant of polycrystalline hexagonal HAp was measured at nine different frequencies, from 45 kHz to 7.3 MHz for relative porosities ranging from 0.05 to 0.42. At a fixed frequency, the decrease in k as a function of increasing porosity is described well by an exponential function of porosity such that k = k0exp(−bP), where k0 is the dielectric constant at zero porosity and b is a constant. In addition, the entire data set of 108 data points (representing the 12 specimens of differing porosity measured at each of the nine frequencies) was fit to a candidate function formed from the product k0exp(−bP) and a simple expression relating frequency to the dielectric constant. The candidate function fit the data relatively well, with a coefficient of determination of 0.91. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 60: 643–650, 2002
Interaction of oxidation and crosslinking in gamma‐irradiated ultrahigh molecular‐weight polyethylene
Authors: Shen Fu‐Wen , McKellop Harry A.
Published: August 2002

The interaction between oxidation and crosslinking in gamma‐irradiated ultrahigh molecular‐weight polyethylene with and without artificial aging was studied. The effect of the atmosphere during irradiation (air vs. low oxygen) occurred primarily within about 0.5 mm of the surface, that is, the depth to which oxygen had diffused when the polyethylene specimen was machined and when it was irradiated. Irradiation in the presence of oxygen induced oxidation instead of crosslinking, so that the level of crosslinking achieved was lower than that which normally would occur at the same dose in the absence of oxygen. Subsequent artificial aging reduced the gel content (crosslinking) and had a maximal effect on the surface and subsurface regions for the gamma–air and gamma–low oxygen polyethylenes, respectively. Thus the storage environments and durations prior to irradiation and prior to artificial aging must be taken into account when attempting to duplicate the oxidation–crosslinking profiles that occur with actual implants in clinical use. In addition, the oxidation mechanisms initiated by the artificial aging method used in this study (i.e., heating in air to 80°C) initiated somewhat different oxidative reactions from those that occur during prolonged shelf life at room temperature or in vivo. In particular, the formation of a peak of oxidation below the free surface of the polyethylene is due to the combined effects of the distribution of residual free radicals and the diffusion gradient of the oxygen. The interactive relationship between oxidation and crosslinking characterized in the present study provides a fundamental basis for understanding the wear behavior of gamma‐sterilized components in past clinical use. It also provides guidelines for the development of polyethylenes with improved resistance to oxidation and wear, with particular relevance to estimation of the amount of crosslinking need‐ ed to potentially eliminate the clinical problem of osteolysis. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 430–439, 2002
Adsorption and release properties of growth factors from biodegradable implants
Authors: Ziegler J. , Mayr‐Wohlfart U. , Kessler S. , Breitig D. , Günther K.‐P.
Published: August 2002

The present investigation was performed to study the adsorption behavior of growth factors and their release characteristics from biodegradable implants in an in vitro study. We investigated the stability of growth factors administered on various scaffolds. We used porous tricalcium phosphate ceramics (α‐TCP), a neutralized glass‐ceramics (GB9N), a composite (polylactid/‐glycolid/GB9N), and solvent dehydrated human bone as carriers. Block shaped scaffolds (sized: 7 × 7 × 10 mm) were loaded with 5 μg of either bone morphogenetic protein (rxBMP‐4), basic fibroblast growth factor (rh‐bFGF), or vascular endothelial growth factor (rh‐VEGF) solved in 150 μL PBS. The growth factors were labeled with Iodine125 (I‐125) for detecting the adsorbed and released amount of growth factors by counting the samples for total I‐125 activity. We observed that the adsorption of these growth factors seems to depend on two different parameters: first on the nature of the tested material, and second on the growth factors on their own. The release kinetics of the growth factors from the biodegradable implants can be described as a two phase process—a very rapid release during the first hours by an elution of not adsorbed protein, followed by a specific release, which depends upon the chemical/physical interaction of the material and the growth factor used. Analyzing the eluted proteins on SDS‐PAGEs rh‐VEGF was degraded into a smaller fragment with a size of around 15 kDa, while rxBMP‐4 and rh‐bFGF showed a complete degradation into fragments smaller than 3 kDa after more than 3 days. Although this in vitro study suggests that biodegradable implants might be successfully used as carriers for osteogenic growth factors, the different release kinetics as well as the alteration of their molecular structure including loss of biological activity should be considered. © 2001 Wiley Periodicals, Inc. J Biomed Mater Res 59: 422–428, 2002
Activation of a stress‐induced gene by insecticides in the midge, Chironomus yoshimatsui
Authors: Yoshimi Tatsuya , Minowa Kozue , Karouna‐Renier Natalie K. , Watanabe Chiharu , Sugaya Yoshio , Miura Takashi
Published: August 2002

Stress proteins (heat shock proteins, HSPs) have been proposed as general biomarkers for environmental monitoring. In the present study, we evaluated the environmental stress‐burden on the aquatic midge Chironomus yoshimatsui using hsp70 expression. Larvae collected from streams receiving polluted runoff (field strain) were resistant to the organophosphorus insecticide, fenitrothion (F), and the synthetic pyrethroid, ethofenprox (E), whereas a strain originally collected from an unpolluted area (susceptible strain) showed low resistance to insecticide exposure. To examine the expression of an HSP70 gene in C. yoshimatsui, an hsp70 cDNA probe was prepared using RNA obtained from the field strain larvae and used for Northern blot analyses. The expression of this HSP70 gene in larvae collected from two field sites in May about 1 week after insecticide spraying in the fields was 2.3 (p = 0.018) to 3.3 fold higher than that in the susceptible strain and was also 4.6 and 1.4 (p = 0.033) fold higher than those collected in November 3 months after the cessation of insecticide spraying. In order to identify potential inducers of the HSP70 gene of the field strain, larvae of the susceptible strain were exposed to F or E for 24 h and hsp70 mRNA levels determined. Exposures to F at 0.4 μg/L and E at 1.1 μg/L increased hsp70 mRNA levels 2.7 (p = 0.049) and 4.4 (p = 0.043) fold over controls, respectively. These results suggest that larvae collected from polluted areas are burdened by environmental stressors and the tested insecticides are potential inducers of HSP70. The results also support the suggestion that HSP70 gene expression is a sensitive indicator of low level (nonlethal) exposures to certain insecticides. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:10–17, 2002; DOI 10.1002/jbt.10018
Effect of peroxisome proliferators on the methylation and protein level of the c‐myc protooncogene in B6C3F1 mice liver
Authors: Ge Rongrong , Tao Lianhui , Kramer Paula M. , Cunningham Michael L. , Pereira Michael A.
Published: August 2002

Peroxisome proliferators in general are nongenotoxic mouse liver carcinogens for which DNA hypomethylation and altered gene expression are proposed mechanisms. Therefore, the peroxisome proliferators 2,4‐dichlorophenoxyacetic acid (2,4‐D), dibutyl phthalate (DBP), gemfibrozil, and Wy‐14,643 were evaluated for the ability to alter the methylation and expression of the c‐myc protooncogene. Male B6C3F1 mice were administered for 6 days in their diet Wy‐14,643 (5–500 ppm), 2,4‐D (1,680 ppm), DBP (20,000 ppm), or gemfibrozil (8,000 ppm). All four peroxisome proliferators caused hypomethylation of the c‐myc gene in the liver. Wy‐14,643 appeared to be the most efficacious with a threshold between 10 and 50 ppm. The level of the c‐myc protein was increased by Wy‐14,643, but not the other peroxisome proliferators. When female B6C3F1 mice received a two‐thirds partially hepatectomy and 16 h later were administered 50 mg/kg Wy‐14,643 by gavage, hypomethylation of the gene occurred 24 h later. Hypomethylation was not found in mice that received Wy‐14,643 following a sham operation. Hypomethylation of the c‐myc gene within 24 h of administering Wy‐14,643 after a partial hepatectomy but not after a sham operation supports the hypothesis that the peroxisome proliferators prevent methylation of hemimethylated sites formed by DNA replication. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:41–47, 2002; DOI 10.1002/jbt.10019
The cellular prion protein: A new partner of the lectin CBP70 in the nucleus of NB4 human promyelocytic leukemia cells*
Authors: Rybner C. , Finel‐Szermanski S. , Felin M. , Sahraoui T. , Rousseau C. , Fournier J.‐G. , Sève A.‐P. , Botti J.
Published: August 2002

Prion diseases are characterized by the presence of an abnormal isoform of the cellular prion protein (PrPc) whose physiological role still remains elusive. To better understand the function of PrPc, it is important to identify the different subcellular localization(s) of the protein and the different partners with which it might be associated. In this context, the PrPc–lectins interactions are investigated because PrPc is a sialoglycoprotein which can react with lectins which are carbohydrate‐binding proteins. We have previously characterized a nuclear lectin CBP70 able to recognize N‐acetyl‐β‐d‐glucosamine residues in HL60 cells. Using confocal immunofluorescence, flow‐cytofluorometry, and Western‐blotting, we have found that PrPc is expressed in the nucleus of the NB4 human promyelocytic leukemia cell line. It was also found that the lectin CBP70 is localized in NB4 cell nuclei. Moreover, several approaches revealed that PrPc and CBP70 are colocalized in the nucleus. Immunoprecipitation experiments showed that these proteins are coprecipitated and interact via a sugar‐dependent binding moiety. In conclusion, PrPc and CBP70 are colocalized in the nuclear compartment of NB4 cells and this interaction may be important to better understand the biological function and possibly the conversion process of PrPc into its pathological form (PrPsc). J. Cell. Biochem. 84: 408–419, 2002. © 2001 Wiley‐Liss, Inc.
Role of N‐cadherin‐ and integrin‐based costameres in the development of rat cardiomyocytes
Authors: Wu Jiahn‐Chun , Sung Hsin‐Ching , Chung Tun‐Hui , DePhilip Robert M.
Published: August 2002

Costameres, vinculin‐containing structures found in skeletal and cardiac muscle, are thought to anchor the Z‐discs of the peripheral myofibrils to the sarcolemma. Several lines of evidence indicate that two different sets of costameres, integrin‐ and N‐cadherin‐based, are present in cardiac muscles. In this study, immunoblot analysis was used to study the expression of N‐cadherin, α‐catenin, β‐catenin, vinculin, talin, and laminin in rat cardiac muscles at embryonic days 15 and 19, the day of birth (postnatal day 0), postnatal weeks 1, 2, 3, and 4, and in the adult. Double immunofluorescence microscopy was performed to study the spatial and temporal distribution of these two sets of costameres in rat cardiomyocytes. Costameric staining for N‐cadherin, codistributed with β‐catenin, was strong from embryonic day 15 up to postnatal week 2, gradually decreased after postnatal week 3, and was undetectable at postnatal week 4 and in the adult. Confocal microscopy showed that N‐cadherin colocalized with α‐actinin at cortical myofibrils. Double‐labeling of β‐catenin and talin indicated the coexistence of N‐cadherin/catenin‐ and integrin/talin‐based costameres in rat cardiac muscle. Although β‐catenin and vinculin were co‐localized at the costamere of cardiomyocytes from embryonic day 15 to postnatal week 3, staining for β‐catenin or talin was mutually exclusive at all stages examined. These results demonstrate the simultaneous, but mutually exclusive, existence of N‐cadherin/catenin‐ and integrin/talin‐based costameres in rat cardiomyocytes between late embryonic stages and postnatal week 3, while only integrin/talin‐based costameres were found in adult rats. The N‐cadherin/catenin‐based costameres in rat cardiac muscles may play a role in myofibrillogenesis similar to that of their counterparts in cultured cardiomyocytes. J. Cell. Biochem. 84: 717–724, 2002. © 2002 Wiley‐Liss, Inc.
Isolation of baculovirus‐expressed human vitamin D receptor: DNA responsive element interactions and phosphorylation of the purified receptor
Authors: Jurutka Peter W. , MacDonald Paul N. , Nakajima Shigeo , Hsieh Jui‐Cheng , Thompson Paul D , Whitfield G. Kerr , Galligan Michael A. , Haussler Carol A. , Haussler Mark R.
Published: August 2002

Two controversial aspects in the mechanism of human vitamin D receptor (hVDR) action are the possible significance of VDR homodimers and the functional role of receptor phosphorylation. To address these issues, milligram quantities of baculovirus‐expressed hVDR were purified to 97% homogeneity, and then tested for binding to the rat osteocalcin vitamin D responsive element (VDRE) via electrophoretic mobility shift and half‐site competition assays in the presence or absence of a CV‐1 nuclear extract containing retinoid X receptor (RXR). Methylation interference analysis revealed that both the hVDR homodimer and the VDR‐RXR heterodimer display similar patterns of VDRE G‐base protection. However, in competition studies, the relative dissociation of the homodimeric hVDR complex from the VDRE was extremely rapid (t1/2 < 30 s) compared to the dissociation of the heteromeric complex (t1/2 > 5 min), thus illustrating the relative instability and low affinity of homodimeric VDR binding to DNA. These results indicate that VDR‐RXR heterodimers are the preferred VDRE binding species. Further, two dimensional gel electrophoresis of hVDR demonstrated several isoelectric forms of the receptor, suggesting that it is subject to multiple phosphorylation events. In vitro kinase assays confirmed that purified hVDR is an efficient substrate for protein kinases A and Cβ, as well as casein kinase II. In vivo studies of the expressed receptor in intact cells, namely baculovirus vector infected Sf9 insect cells and transfected mammalian COS‐7 cells, demonstrated that hVDR was phosphorylated in a hormone‐enhanced fashion. Functional consequences of hVDR phosphorylation were suggested by the observations that: (i) potato acid phosphatase (PAP)‐treated hVDR no longer interacted with the VDRE as either a homodimer or a heteromeric complex with RXR, and (ii) treatment of transfected COS‐7 cells with a phosphatase inhibitor (okadaic acid) along with 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) resulted in a synergistic enhancement of both hVDR phosphorylation and transactivation of a VDRE‐linked reporter gene, compared to the effect of treatment with either agent alone. These studies point to a significant role for phosphorylation of VDR in regulating high‐affinity VDR‐RXR interactions with VDREs, and also in modulating 1,25(OH)2D3‐elicited transcriptional activation in target cells. J. Cell. Biochem. 85: 435–457, 2002. © 2002 Wiley‐Liss, Inc.
Role of mTOR in the degradation of IRS‐1: Regulation of PP2A activity
Authors: Hartley David , Cooper Geoffrey M.
Published: August 2002

We have investigated the role of PI 3‐kinase and mTOR in the degradation of IRS‐1 induced by insulin. Inhibition of mTOR with rapamycin resulted in approximately 50% inhibition of the insulin‐induced degradation of IRS‐1. In contrast, inhibition of PI‐3 kinase, an upstream activator of mTOR, leads to a complete block of the insulin‐induced degradation. Inhibition of either PI‐3 kinase or mTOR prevented the mobility shift in IRS‐1 in response to insulin, a shift that is caused by Ser/Thr phosphorylation. These results indicate that insulin stimulates PI 3‐kinase‐mediated degradation of IRS‐1 via both mTOR‐dependent and ‐independent pathways. Platelet‐derived growth factor (PDGF) stimulation leads to a lower level of degradation, but significant phosphorylation of IRS‐1. Both the degradation and phosphorylation of IRS‐1 in response to PDGF are completely inhibited by rapamycin, suggesting that PDGF stimulates IRS‐1 degradation principally via the mTOR‐dependent pathway. Inhibition of the serine/threonine phosphatase PP2A with okadaic acid also induced the phosphorylation and degradation of IRS‐1. IRS‐1 phosphorylation and degradation in response to okadaic acid were not inhibited by rapamycin, suggesting that the action of mTOR in the degradation of IRS‐1 results from inhibition of PP2A. Consistent with this, treatment of cells with rapamycin stimulated PP2A activity. While the role of mTOR in the phosphorylation of IRS‐1 appears to proceed primarily through the regulation of PP2A, we also provide evidence that the regulation of p70S6 kinase phosphorylation requires the direct activity of mTOR. J. Cell. Biochem. 85: 304–314, 2002. © 2002 Wiley‐Liss, Inc.
Characterization of a 150 kDa accessory receptor for TGF‐β1 on keratinocytes: Direct evidence for a GPI anchor and ligand binding of the released form
Authors: Tam B.Y.Y. , Larouche D. , Germain L. , Hooper N.M. , Philip A.
Published: August 2002

Transforming growth factor‐β (TGF‐β) is a key modulator of epidermal development and homeostasis, and has been shown to potently regulate keratinocyte migration and function during wound repair. There are three cloned TGF‐β receptors termed type I, type II, and type III that are found on most cell types. The types I and II are the signaling receptors, while the type III is believed to facilitate TGF‐β binding to the types I and II receptors. Recently, we reported that in addition to these receptors, human keratinocytes express a 150 kDa TGF‐β1 binding protein (r150) which forms a heteromeric complex with the TGF‐β signaling receptors. This accessory receptor was described as glycosyl phosphatidylinositol‐specific anchored based on its sensitivity to phosphatidylinositol phospholipase C (PIPLC). In the present study, we demonstrate that the GPI‐anchor is contained in r150 itself and not on a tightly associated protein and that it binds TGF‐β1 with an affinity similar to those of the types I and II TGF‐β signaling receptors. Furthermore, the PIPLC released (soluble) form of this protein is capable of binding TGF‐β1 independently from the signaling receptors. In addition, we provide evidence that r150 is released from the cell surface by an endogenous phospholipase C. Our observation that r150 interacts with the TGF‐β signaling receptors, together with the finding that the soluble r150 binds TGF‐β1 suggest that r150 in either its membrane anchored or soluble form may potentiate or antagonize TGF‐β signaling. Elucidating the mechanism by which r150 functions as an accessory molecule in TGF‐β signaling may be critical to understanding the molecular mechanisms underlying the regulation of TGF‐β action in keratinocytes. J. Cell. Biochem. 83: 494–507, 2001. © 2001 Wiley‐Liss, Inc.
Cloning and characterization of human syndecan‐3*
Authors: Berndt Christine , Casaroli‐Marano Ricardo P. , Vilaró Senén , Reina Manuel
Published: August 2002

Syndecans are cell‐surface heparan sulfate proteoglycans, which perform a variety of functions in the cell. Most important, they are co‐receptors for growth factors and mediate cell–cell and cell–matrix interactions. Four syndecans (syndecan 1–4) have been described in different species. The aim of this work was the cloning and characterization of human syndecan‐3. The human syndecan‐3 sequence has high homology to the rat and mouse sequences, with the exception of the 5′‐region. Syndecan‐3 mRNA is mostly expressed in the nervous system, the adrenal gland, and the spleen. When different cell lines were transiently transfected with full‐length syndecan‐3 cDNA, it was localized to the membrane and induced the formation of long filopodia‐like structures, microspikes, and varicosities. Consequently, the actin cytoskeleton was re‐organized, since actin staining was mostly found in the cellular extensions and at the cell periphery, co‐localizing with the syndecan‐3 staining. The development of the phenotype depended on the presence of sugar chains, as transfected glycosaminoglycan‐deficient Chinese hamster ovary (CHO) 745 cells did not show these structural changes, nor did transfected CHO K1 cells in the presence of heparin. The similarity of the cloned DNA sequence with that of other mammalian species and the high expression in the nervous system led us to the assumption that human syndecan‐3 could perform comparable functions to those described for syndecan‐3 in rat and mouse. Additionally, transient transfection experiments suggest a role of human syndecan‐3 in the organization of cell shape by affecting the actin cytoskeleton, possibly by transferring signals from the cell surface in a sugar‐dependent mechanism. J. Cell. Biochem. 82: 246–259, 2001. © 2001 Wiley‐Liss, Inc.
Regulation of the Akt/Glycogen synthase kinase‐3 axis by insulin‐like growth factor‐II via activation of the human insulin receptor isoform‐A
Authors: Scalia Pierluigi , Heart Emma , Comai Lucio , Vigneri Riccardo , Sung Chin K.
Published: August 2002

Insulin‐like growth factor II (IGF‐II) plays a key role in mitogenesis during development and tumorigenesis and is believed to exert its mitogenic functions mainly through the IGF‐I receptor. Recently, we identified the insulin receptor isoform A (IRA) as an additional high affinity receptor for IGF‐II in both fetal and cancer cells. Here we investigated the mitogenic signaling of IGF‐II via the Akt/Glycogen synthase kinase 3 (Gsk3) axis employing R‐IRA cells that are IGF‐I receptor null mouse embryonic fibroblasts expressing the human IRA. IGF‐II induced activation of the proto‐oncogenic serine kinase Akt, reaching maximal at 5–10 min. IGF‐II also caused the rapid and sustained deactivation of glycogen synthase kinase 3‐beta (Gsk3β), reaching maximal at 1–3 min, shortly preceding, therefore, maximal activation of Akt. Under our conditions, IGF‐II and insulin induced 70–80% inhibition of Gsk3βactivity. In these cells IGF‐II also deactivated Gsk3α although less effectively than Gsk3β. In parallel experiments, we found that IGF‐II induced transient activation of extracellular‐signal‐regulated kinases (Erk) reaching maximal at 5–10 min and decreasing thereafter. Time courses and potencies of regulation of both mitogenic pathways (Akt/Gsk3β and Erk) by IGF‐II via IRA were similar to those of insulin. Furthermore, IGF‐II like insulin effectively stimulated cell cycle progression from the G0/G1 to the S and G2/M phases. Interestingly, AP‐1‐mediated gene expression, that was reported to be negatively regulated by Gsk3β was only weakly increased after IGF‐II stimulation. Our present data suggest that the coordinated activation or deactivation of Akt, Gsk3β, and Erk may account for IGF‐II mitogenic effects and support an active role for IRA in IGF‐II action. J. Cell. Biochem. 82: 610–618, 2001. © 2001 Wiley‐Liss, Inc.
Tumor necrosis factor‐α mediates RANK ligand stimulation of osteoclast differentiation by an autocrine mechanism†
Authors: Zou Wei , Hakim Imad , Tschoep Katharina , Endres Stefan , Bar‐Shavit Zvi
Published: August 2002

Osteoblasts or bone marrow stromal cells are required as supporting cells for the in vitro differentiation of osteoclasts from their progenitor cells. Soluble receptor activator of nuclear factor‐κB ligand (RANKL) in the presence of macrophage colony‐stimulating factor (M‐CSF) is capable of replacing the supporting cells in promoting osteoclastogenesis. In the present study, using Balb/c‐derived cultures, osteoclast formation in both systems—osteoblast/bone‐marrow cell co‐cultures and in RANKL‐induced osteoclastogenesis—was inhibited by antibody to tumor necrosis factor‐α (TNF‐α), and was enhanced by the addition of this cytokine. TNF‐α itself promoted osteoclastogenesis in the presence of M‐CSF. However, even at high concentrations of TNF‐α the efficiency of this activity was much lower than the osteoclastogenic activity of RANKL. RANKL increased the level of TNF‐α mRNA and induced TNF‐α release from osteoclast progenitors. Furthermore, antibody to p55 TNF‐α receptors (TNF receptors‐1) (but not to p75 TNF‐α receptors (TNF receptors‐2) inhibited effectively RANKL‐ (and TNF‐α() induced osteoclastogenesis. Anti‐TNF receptors‐1 antibody failed to inhibit osteoclastogenesis in C57BL/6‐derived cultures. Taken together, our data support the hypothesis that in Balb/c, but not in C57BL/6 (strains known to differ in inflammatory responses and cytokine modulation), TNF‐α is an autocrine factor in osteoclasts, promoting their differentiation, and mediates, at least in part, RANKL's induction of osteoclastogenesis. © 2001 Wiley‐Liss, Inc.
Hypoxia‐induced increase in intracellular calcium concentration in endothelial cells: Role of the Na+‐glucose cotransporter
Authors: Berna Nancy , Arnould Thierry , Remacle José , Michiels Carine
Published: August 2002

Hypoxia is a common denominator of many vascular disorders, especially those associated with ischemia. To study the effect of oxygen depletion on endothelium, we developed an in vitro model of hypoxia on human umbilical vein endothelial cells (HUVEC). Hypoxia strongly activates HUVEC, which then synthesize large amounts of prostaglandins and platelet‐activating factor. The first step of this activation is a decrease in ATP content of the cells, followed by an increase in the cytosolic calcium concentration ([Ca2+]i) which then activates the phospholipase A2 (PLA2). The link between the decrease in ATP and the increase in [Ca2+]i was not known and is investigated in this work. We first showed that the presence of extracellular Na+ was necessary to observe the hypoxia‐induced increase in [Ca2+]i and the activation of PLA2. This increase was not due to the release of Ca2+ from intracellular stores, since thapsigargin did not inhibit this process. The Na+/Ca2+ exchanger was involved since dichlorobenzamil inhibited the [Ca2+]i and the PLA2 activation. The glycolysis was activated, but the intracellular pH (pHi) in hypoxic cells did not differ from control cells. Finally, the hypoxia‐induced increase in [Ca2+]i and PLA2 activation were inhibited by phlorizin, an inhibitor of the Na+‐glucose cotransport. The proposed biochemical mechanism occurring under hypoxia is the following: glycolysis is first activated due to a requirement for ATP, leading to an influx of Na+ through the activated Na+‐glucose cotransport followed by the activation of the Na+/Ca2+ exchanger, resulting in a net influx of Ca2+. J. Cell. Biochem. 84: 115–131, 2002. © 2001 Wiley‐Liss, Inc.
Hydrophobic similarity between molecules: A MST‐based hydrophobic similarity index
Authors: Muñoz J. , Barril X. , Hernández B. , Orozco Modesto , Luque F. Javier
Published: August 2002

A similarity index based on the hydrophilic/hydrophobic properties of molecules is presented. Such an index is defined based on the fractional partition of the free energy of solvation developed within the framework of the self‐consistent reaction field MST model, which divides the free energy of solvation or the free energy of transfer into contributions assigned to the surface elements defining the solute/solvent interface. These surface contributions can be integrated to derive atomic or group contributions. The suitability of the index to compute the molecular similarity based on hydrophobic/hydrophilic properties is examined by considering their application in a variety of test systems, including structure‐activity relationships, absorption properties, and molecular recognition. The similarity index is expected to be a very powerful tool in molecular similarity studies for compounds of chemical, biochemical, and pharmaceutical interest. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 554–563, 2002; DOI 10.1002/jcc.10055
Multidimensional scaling of combinatorial libraries without explicit enumeration
Authors: Agrafiotis Dimitris K. , Lobanov Victor S.
Published: August 2002

A novel approach for the multidimensional scaling of large combinatorial libraries is presented. The method employs a multilayer perceptron, which is trained to predict the coordinates of the products on the nonlinear map from pertinent features of their respective building blocks. This method limits the expensive enumeration and descriptor generation to only a small fraction of products and, in addition, relieves the enormous computational effort required for the low‐dimensional embedding by conventional iterative multidimensional scaling algorithms. In effect, the method provides an explicit mapping function from reagents to products, and allows the vast majority of compounds to be projected without constructing their connection tables. The advantages of this approach are demonstrated using two combinatorial libraries based on the reductive amination and Ugi reactions, and three descriptor sets that are commonly used in similarity searching, diversity profiling and structure–activity correlation. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1712–1722, 2001
Classification of 6‐(14,7,4) designs with nontrivial automorphism groups
Authors: Khosrovshahi G. B. , Mohammad‐Noori M. , Tayfeh‐Rezaie B.
Published: August 2002

In this paper, we introduce some intersection matrices for t‐designs. Utilizing these matrices together with a modified version of a backtracking algorithm, we classify all 6‐(14,7,4) and 5‐(13,6,4) designs with nontrivial automorphism groups and obtain 13 and 21 such designs, respectively. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 180–194, 2002; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/jcd.10004
Specificity of autoantibodies to SS‐A/Ro on a transfected and overexpressed human 60 kDa Ro autoantigen substrate
Authors: Fritzler Marvin J. , Hanson Cheryl , Miller Joan , Eystathioy Theophany
Published: August 2002

The objective of this study was to analyze apparently discrepant results that arose during the use of an indirect immunofluorescence (IIF) assay using transfected HEp‐2 cells to detect anti‐SS‐A/Ro autoantibodies in human sera. Fourteen sera that had SS‐A/Ro antibodies as detected on this commercial substrate, but did not have antibodies to SS‐A/Ro as determined by double immunodiffusion (ID) or enzyme‐linked immunosorbent assay (ELISA), were studied by immunoprecipitation (IP) of radiolabeled cell extracts and full‐length recombinant SS‐A/Ro. A multi‐antigen strip immunoblotting (IB) assay containing both the 52‐ and 60‐kDa antigens was included in the analysis. We confirmed that 12 of 14 of the sera under study had antibodies to SS‐A/Ro protein antigens as determined by at least one other immunoassay. One serum had antibodies to hyRNA but no detectable reactivity with the 52‐ or 60‐kDa antigens. One serum remained negative in all assays for SS‐A/Ro autoantibodies. J. Clin. Lab. Anal. 16:103–108, 2002. © 2002 Wiley‐Liss, Inc.
Simultaneous determination of total plasma glutathione, homocysteine, cysteinylglycine, and methionine by high‐performance liquid chromatography with electrochemical detection
Authors: Houze Pascal , Gamra Stéphanie , Madelaine Isabelle , Bousquet Bernard , Gourmel Bernard
Published: August 2002

We here describe an ion‐exchange high‐performance liquid chromatography technique with electrochemical detection for rapid quantification of glutathione, homocysteine, cysteinylglycine, and methionine. The analytical validation of the technique showed within‐assay and between‐assay coefficients of variation between 3.1 and 4.3%, and 3.7 and 8.6%, respectively. Percentages of recovery for overload and dilution tests were between 87 and 120%. Detection limits were 1 μmol/L for methionine and 0.5 μmol/L for other compounds. There was no interference with any physiological and pharmacological substances possessing a thiol function. Aminothiol concentrations determined in 100 control subjects (50 women and 50 men) showed no age‐ or sex‐rated differences for except for homocysteine which was increased (+ 28%) in oldest subjects of both sexes. In 60 patients at risk (30 with chronic renal failure, 30 with diabetes), homocysteine concentration was significantly increased. No variation in other aminothiols was observed in diabetic subjects. Methionine was decreased and cysteinylglycine was increased in patients with chronic renal failure. The present technique—rapid, easy to use, and reliable—appears suitable for routine application in the exploration of aminothiol metabolic pathways including mechanisms of hyperhomocysteinemia. J. Clin. Lab. Anal. 15:144–153, 2001. © 2001 Wiley‐Liss, Inc.
Differential item functioning in a Spanish translation of the Beck Depression Inventory
Authors: Azocar Francisca , Areán Patricia , Miranda Jeanne , Muñoz Ricardo F.
Published: August 2002

Brief and culturally compatible measures of depression are necessary, yet most depression scales are translated without regard for cultural biases. In this study, 292 medical outpatients completed an English or a Spanish‐translated and back‐translated version of the Beck Depression Inventory (BDI). The BDI items were analyzed for bias between Spanish and English‐speaking patients to determine the equivalence of the scale. A Differential Item Function (DIF) using a Mantel Haenszel Approach for Ordered Response Categories was used to analyze how likely subjects in the two ethnic groups were to endorse each response category. The results suggest that regardless of level of depression, Latinos are more likely to endorse items reflecting tearfulness and punishment, and less likely to endorse inability to work. Cultural interpretations and recommendations for use of the BDI are discussed. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 355–365, 2001.
Thought Field Therapy: Response to our critics and a scrutiny of some old ideas of social science
Authors: Callahan Roger J.
Published: August 2002

Thought Field Therapy (TFT) is criticized for not following the usual social science guidelines in research that is appropriate for minimum impact therapies. The usual research guidelines are due to a social science bias where crucial subjective reports are ignored, where tests of statistical significance and control groups are required. TFT may be closer to “hard science” than social science due to extraordinarily high level of success. A few valid points are acknowledged and were already covered, such as importance of autonomic balance when raising SDNN and necessity to restrict movement when electrocardiograph methods not used in measuring heart rate variability. Rejected as possible explanations of TFT's robust results are: placebo, regression to the mean (inappropriate in high and low heart rate variability), and passage of time when such time is merely minutes. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 1251–1260, 2001.
Depressive symptom patterns in patients with Parkinson's disease and other older adults
Authors: Erdal Kristi J.
Published: August 2002

Research on depression in Parkinson's disease (PD) has suggested that PD patients experience a qualitatively different depression from that of other older adults, endorsing fewer cognitive symptoms of depression (e.g., guilt, failure) and greater somatic (e.g., poor sleep) and mood symptoms (e.g., sadness, hopelessness); however, this has never been tested directly. In the present study, two PD groups, one with cognitive impairment (PD + CI; n = 26) and one without cognitive impairment (PD; n = 45), and three control groups of older adults were compared on measures of depressive symptomatology. The control groups included a physically disabled group (n = 46), a cognitively impaired group (CI; n = 21), and a healthy group (n = 50). Confirmatory factor analysis verified a four‐factor model of depressive symptoms (Cognitive, Mood, Somatic, and Fatigue symptoms). Comparisons revealed that the PD group had a depressive‐symptom pattern that was not significantly different from the disabled and healthy groups. The PD + CI group had a symptom pattern that was more similar to the CI group than to the PD group. Implications for the conceptualization of depression in older adults are discussed. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 1559–1569, 2001.
Antiscientific attitudes: What happens when scientists are unscientific?
Authors: Beutler Larry E. , Harwood T. Mark
Published: August 2002

Originally published in J Clin Psychol 57: 43–51, 2001.
MMPI‐2 profiles of Gulf and Vietnam combat veterans with chronic posttraumatic stress disorder
Authors: Glenn D. Michael , Beckham Jean C. , Sampson William S. , Feldman Michelle E. , Hertzberg Michael A. , Moore Scott D.
Published: August 2002

The current study examined service era differences in a sample of 172 Gulf and Vietnam outpatient veterans with combat‐related posttraumatic stress disorder (PTSD). Participants completed the MMPI‐2 and several additional self‐report measures of symptom severity (PTSD, depression, anxiety, hostility, and health complaints). Results indicated that MMPI‐2 profiles differed significantly according to service era with Vietnam veterans scoring higher on scales 2, 8, and 0 and lower on scale 9 than did Gulf veterans. Examination of group means derived from parametric analysis of MMPI‐2 data suggested a mean two‐point code type of 2–8/8–2 for Vietnam veterans and 1–8/8–1 for Gulf veterans. In contrast, when the data were examined using descriptive techniques based on frequency counts of individual MMPI‐2 profiles, the most frequently occurring two‐point codetype was 7–8/8–7 for Vietnam veterans, and 6–8/8–6 for Gulf veterans. In addition, Gulf veterans reported a greater number of total health complaints than Vietnam veterans, whereas Vietnam veterans reported a greater number of physician‐diagnosed physical conditions. Potential advantages of incorporating descriptive approaches versus parametric methods when examining profile data are also presented. © 2002 Wiley Periodicals, Inc. J Clin Psychol 58: 371–381, 2002.
Expression of the thrombin receptor (PAR‐1) during rat skeletal muscle differentiation
Authors: Chevessier Frédéric , Hantaï Daniel , Verdière‐Sahuqué Martine
Published: August 2002

The serine protease thrombin has been proposed to be involved in neuromuscular plasticity. Its specific receptor “protease activated receptor‐1” (PAR‐1), a G protein‐coupled receptor, has been shown to be expressed in myoblasts but not after fusion (Suidan et al., 1996 J Biol Chem 271:29162–29169). In the present work we have investigated the expression of PAR‐1 during rat skeletal muscle differentiation both in vitro and in vivo. Primary cultures of rat foetal skeletal muscle, characterized by their spontaneous contractile activity, were used for exploration of PAR‐1 by RT‐PCR, immunocytochemistry and Western blotting. Our results show that PAR‐1 mRNA and protein are both present in myoblasts and myotubes. Incubation of myotubes loaded with fluo‐3‐AM in presence of thrombin (200 nM) or PAR‐1 agonist peptide (SFLLRN, 500 μM), induced the intracellular release of calcium indicating the activation of PAR‐1. Blockade of contractile activity by tetrodotoxin (TTX, 6 nM) did not modify either PAR‐1 synthesis or its cellular localization. Investigation of PAR‐1 on rat muscle cryostat sections at Day 18 of embryogenesis and postnatal Days 1, 5, and 10 indicated that this protein is first expressed in the cytoplasm and that it later localizes to the membrane. Moreover, its expression correlates with myosin heavy chain transitions occurring during post‐natal period and is restricted to primary fibers. Taken together, these results suggest that PAR‐1 expression is not related to contractile activity but to myogenic differentiation. © 2001 Wiley‐Liss, Inc.
Effect of age and hypoxia on TGFβ1 receptor expression and signal transduction in human dermal fibroblasts: Impact on cell migration
Authors: Mogford Jon E. , Tawil Nabil , Chen Alexandria , Gies David , Xia Yuping , Mustoe Thomas A.
Published: August 2002

Wound healing is critically affected by age, ischemia, and growth factors such as TGFβ1. The combined effect of these factors on fibroblast migration, an essential component of wound healing, is poorly understood. To address this deficiency, we examined expression of TGFβ receptor type I and II (TGFβRI and RII) under normoxia or hypoxia (1% O2) in cultured human dermal fibroblasts (HDFs) from young (ages 24–33) and aged (ages 61–73) adults. TGFβRI and RII expression was similar in both groups under normoxia. Hypoxia did not alter receptor levels in young HDFs but significantly decreased TGFβRI in aged cells (12 and 43%, respectively). Additionally, young cells displayed a 50% increase in activation of p42/p44 mitogen‐activated kinase by TGFβ1 (2–200 pg/ml) under hypoxia while aged cell levels of active p42/p44 decreased up to 24%. To determine functional outcomes of these findings, we measured the migratory capacity of the cells on type I collagen using a gold salt migration assay. Hypoxia increased the migratory index (MI) of young HDFs over normoxia by 30% but had no effect on aged cells. Under normoxia, TGFβ1 (1–1000 pg/ml) increased young HDF migration in a concentration‐dependent manner up to 109% over controls but minimally increased aged HDF migration (37%). Under hypoxia, TGFβ1 significantly increased young cell MI at all concentrations but was without effect on the aged HDF response. These data demonstrate that aged fibroblasts have an impaired migratory capacity with complete loss of responsiveness to hypoxia and deficits in the migratory and signal transduction responsiveness to TGFβ1 that may partly explain diminished healing capabilities often observed in aged patients. J. Cell. Physiol. 190: 259–265, 2002. © 2002 Wiley‐Liss, Inc.
Cultivation of rat marrow‐derived mesenchymal stem cells in reduced oxygen tension: Effects on in vitro and in vivo osteochondrogenesis
Authors: Lennon Donald P. , Edmison John M. , Caplan Arnold I.
Published: August 2002

Rat mesenchymal stem cells (rMSCs) represent a small portion of the cells in the stromal compartment of bone marrow and have the potential to differentiate into bone, cartilage, fat, and fibrous tissue. These mesenchymal progenitor cells were maintained as primary isolates and as subcultured cells in separate closed modular incubator chambers purged with either 95% air and 5% CO2 (20% or control oxygen) or 5% oxygen, 5% CO2, and 90% nitrogen (5% or low oxygen). At first passage, some cells from each oxygen condition were loaded into porous ceramic vehicles and implanted into syngeneic host animals in an in vivo assay for osteochondrogenesis. The remaining cells were continued in vitro in the same oxygen tension as for primary culture or were switched to the alternate condition. The first passage cells were examined for in vitro osteogenesis with assays involving the quantification of alkaline phosphatase activity and calcium and DNA content as well as by von Kossa staining to detect mineralization. Cultures maintained in low oxygen had a greater number of colonies as primary isolates and proliferated more rapidly throughout their time in vitro, as indicated by hemacytometer counts at the end of primary culture and increased DNA values for first passage cells. Moreover, rMSCs cultivated in 5% oxygen produced more bone than cells cultured in 20% oxygen when harvested and loaded into porous ceramic cubes and implanted into syngeneic host animals. Finally, markers for osteogenesis, including alkaline phosphatase activity, calcium content, and von Kossa staining, were elevated in cultures which had been in low oxygen throughout their cultivation time. Expression of these markers was usually increased above basal levels when cells were switched from control to low oxygen at first passage and decreased for cells switched from low to control oxygen. We conclude that rMSCs in culture function optimally in an atmosphere of reduced oxygen that more closely approximates documented in vivo oxygen tension. © 2001 Wiley‐Liss, Inc.
Reduction of telomerase activity in human liver cancer cells by a histone deacetylase inhibitor
Authors: Nakamura Mitsuyasu , Saito Hidetsugu , Ebinuma Hirotoshi , Wakabayashi Kanji , Saito Yoshimasa , Takagi Tamako , Nakamoto Nobuhiro , Ishii Hiromasa
Published: August 2002

The presence of telomerase has been demonstrated recently in many different malignancies. Several reports documented that in human hepatocellular carcinoma, the level of telomerase activity parallels its differentiation stage. In the present study, the effect of the differentiation‐inducing agent sodium butyrate on telomerase activity in four human liver cancer cell lines was investigated using the telomeric repeat amplification protocol. We assayed telomerase activity before and after butyrate treatment and in cell cycle synchronized non‐dividing quiescent cells. In addition, telomerase reverse transcriptase levels were measured at the mRNA level. All four cell lines possessed high but not identical levels of telomerase activity. Telomerase activity was significantly reduced by treatment with sodium butyrate as well as trichostatin A in a dose‐ and time‐dependent fashion, paralleling the reduction of cell proliferation. Although methotrexate, hydroxyurea, and colchicine synchronized the cell cycle at G1, S, and G2/M, respectively, and thereby also caused proliferating cells to cease dividing and become quiescent, in this case telomerase activity remained essentially unaltered compared to the control cultures. Moreover, levels of mRNA encoding telomerase reverse transcriptase were not always significantly altered by either sodium butyrate treatment or cell cycle synchronization. These results suggest that sodium butyrate, as a histone deacetylase inhibitor, effectively reduces telomerase activity without affecting transcription levels of the reverse transcriptase component. © 2001 Wiley‐Liss, Inc.