bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcranial Doppler estimation of cerebral blood flow and cerebrovascular conductance during modified rebreathing
Authors: Claassen Jurgen A. H. R. , Zhang Rong , Fu Qi , Witkowski Sarah , Levine Benjamin D.
Published: November 2006

Clinical transcranial Doppler assessment of cerebral vasomotor reactivity (CVMR) uses linear regression of cerebral blood flow velocity (CBFV) vs. end-tidal CO2 (PetCO2) under steady-state conditions. However, the cerebral blood flow (CBF)-PetCO2 relationship is nonlinear, even for moderate changes in CO2. Moreover, CBF is increased by increases in arterial blood pressure (ABP) during hypercapnia. We used a modified rebreathing protocol to estimate CVMR during transient breath-by-breath changes in CBFV and PetCO2. Ten healthy subjects (6 men) performed 15 s of hyperventilation followed by 5 min of rebreathing, with supplemental O2 to maintain arterial oxygen saturation constant. To minimize effects of changes in ABP on CVMR estimation, cerebrovascular conductance index (CVCi) was calculated. CBFV-PetCO2 and CVCi-PetCO2 relationships were quantified by both linear and nonlinear logistic regression. In three subjects, muscle sympathetic nerve activity was recorded. From hyperventilation to rebreathing, robust changes occurred in PetCO2 (20–61 Torr), CBFV (−44 to +104% of baseline), CVCi (−39 to +64%), and ABP (−19 to +23%) (all P < 0.01). Muscle sympathetic nerve activity increased by 446% during hypercapnia. The linear regression slope of CVCi vs. PetCO2 was less steep than that of CBFV (3 vs. 5%/Torr; P = 0.01). Logistic regression of CBF-PetCO2 ( r2 = 0.97) and CVCi-PetCO2 ( r2 = 0.93) was superior to linear regression ( r2 = 0.91, r2 = 0.85; P = 0.01). CVMR was maximal (6–8%/Torr) for PetCO2 of 40–50 Torr. In conclusion, CBFV and CVCi responses to transient changes in PetCO2 can be described by a nonlinear logistic function, indicating that CVMR estimation varies within the range from hypocapnia to hypercapnia. Furthermore, quantification of the CVCi-PetCO2 relationship may minimize the effects of changes in ABP on the estimation of CVMR. The method developed provides insight into CVMR under transient breath-by-breath changes in CO2.
Estimation of the functional role of arterial pathways to the buttock circulation during treadmill walking in patients with claudication
Authors: Jaquinandi Vincent , Abraham Pierre , Picquet Jean , Paisant-Thouveny Francine , Leftheriotis Georges , Saumet Jean-Louis
Published: November 2006

The aim of the study was to estimate the functional contribution of the arterial inflow pathways to the pelvic circulation during walking in patients with stage 2 lower extremity arterial disease. Transcutaneous oxygen pressure (PtcO2) changes during exercise can be used to estimate the severity of regional blood flow impairment while walking. Seventy patients with stable lower limb claudication were studied using a multivariate linear regression model. The relationship between exercise-induced buttock PtcO2 changes, the ipsilateral calf PtcO2 changes, and the arterial diameters of the pelvic arteriographic pathways were analyzed. The ipsilateral hypogastric and lumbar pathway, as well as the ipsilateral calf PtcO2 changes, were the only variables significantly related to buttock PtcO2 changes ( r = 0.47; P < 0.001). Their normalized respective contribution to the regressive model was 39%, 19%, and 18%. None of the contralateral hypogastric, mesenteric, and sacral pathways or pathways stemming from the external iliac artery showed significant correlation to buttock PtcO2 changes. The ipsilateral hypogastric and ipsilateral lumbar pathways are the major pathways responsible for the functional buttock blood flow supply during walking. The role of contralateral hypogastric, inferior mesenteric, and median sacral pathways and arteries distal to the internal iliac trunk is negligible in the normal or compensatory blood flow supply. Distal PtcO2 decrease at exercise aggravates proximal PtcO2 decrease, possibly through the occurrence of a “steal phenomenon” of distal over proximal circulation during walking.
The Tumor Suppressor KLF11 Mediates a Novel Mechanism in Transforming Growth Factor β–Induced Growth Inhibition That Is Inactivated in Pancreatic Cancer
Authors: Buck Anita , Buchholz Malte , Wagner Martin , Adler Guido , Gress Thomas , Ellenrieder Volker
Published: November 2006

c-myc promoter silencing is a key step in epithelial cell growth inhibition by transforming growth factor β (TGFβ). During carcinogenesis, however, epithelial cells escape from c-myc repression and consequently become refractory to TGFβ-mediated antiproliferation. Here, we assessed the role of the repressor, KLF11, in TGFβ-induced growth inhibition in normal epithelial as well as pancreatic carcinoma cells. Endogenous KLF11 was stably down-regulated by RNA interference technology, and the functional consequences were studied by proliferation assays, reporter assays, DNA binding studies, and expression analyses. Coimmunoprecipitation and glutathione S-transferase pulldown assays were conducted to define KLF11-Smad3 interaction and U0126 was administered to examine the effects of the extracellular signal-regulated kinase (ERK)–mitogen-activated protein kinase on complex formation and c-myc promoter binding of KLF11 and Smad3 in pancreatic cancer cells. In TGFβ-stimulated normal epithelial cells, nuclear KLF11, in concert with Smad3, binds to and represses transcription from the core region of the TGFβ-inhibitory element (TIE) of the c-myc promoter. Disruption of KLF11-Smad3 interaction or small interfering RNA–mediated knockdown of endogenous KLF11 strongly diminishes Smad3-TIE promoter binding and repression, and consequently impairs TGFβ-mediated growth inhibition. In pancreatic cancer cells with oncogenic Ras mutations, hyperactive ERK counteracts TGFβ-induced c-myc repression and growth inhibition through at least two mechanisms, i.e., via disruption of KLF11-Smad3 complex formation and through inhibition of KLF11-Smad3 binding to the TIE element. Together, these results suggest a central role for KLF11 in TGFβ-induced c-myc repression and antiproliferation and identifies a novel mechanism through which ERK signaling antagonizes the tumor suppressor activities of TGFβ in pancreatic cancer cells with oncogenic Ras mutations. (Mol Cancer Res 2006;4(11):861–72)
Lipocalin 2 Antagonizes the Proangiogenic Action of Ras in Transformed Cells
Authors: Venkatesha Shivalingappa , Hanai Jun-ichi , Seth Pankaj , Karumanchi S. Ananth , Sukhatme Vikas P.
Published: November 2006

Lipocalin 2 is an iron-binding secreted protein that converts embryonic kidney mesenchyme to epithelia. Previously, we reported that lipocalin 2 could revert 4T1-ras-transformed mesenchymal tumor cells to a more epithelial phenotype, increase E-cadherin expression, and suppress cell invasiveness in vitro and in vivo, indicating that lipocalin 2 is a metastasis suppressor. Here, we show that lipocalin 2 can suppress the ras-induced expression of vascular endothelial growth factor in 4T1 cells via down-regulation of ras mitogen-activated protein kinase and ras phosphatidylinositol-3-kinase signaling. In addition, the expression of thrombospondin-1 (an antiangiogenic molecule) was increased in tumors formed by 4T1-ras cells into which lipocalin 2 was stably introduced. Tumor angiogenesis, assessed via an intradermal tumor angiogenesis assay, was also suppressed by lipocalin 2. We also show that caveolin-1 is a critical mediator of this activity. These data provide new insights into the action of lipocalin 2 and raise the possibility that the administration of lipocalin 2 may be useful for inhibiting tumor angiogenesis, in addition to suppressing tumor metastasis, in cancers which show ras activation. (Mol Cancer Res 2006;4(11):821–9)
Enhanced Expression of LKB1 in Breast Cancer Cells Attenuates Angiogenesis, Invasion, and Metastatic Potential
Authors: Zhuang Zhi-Gang , Di Gen-Hong , Shen Zhen-Zhou , Ding Jian , Shao Zhi-Ming
Published: November 2006

LKB1 (also known as STK11) is a recently identified tumor suppressor gene whose mutation can lead to Peutz-Jeghers syndrome, which is characterized by gastrointestinal polyps and cancers of different organ systems. Approximately 30% of sporadic breast cancer samples express low levels of LKB1. This suggests that the LKB1 gene may be related to the tumorigenesis of breast cancer. We reintroduced LKB1 into MDA-MB-435 breast cancer cells that lack the LKB1 gene to investigate how overexpression of LKB1 affects tumor invasiveness and metastasis. Overexpression of the LKB1 protein in breast cancer cells resulted in significant inhibition of in vitro invasion. In vivo, LKB1 expression reduced tumor growth in the mammary fat pad, microvessel density, and lung metastasis. LKB1 overexpression was associated with down-regulation of matrix metalloproteinase-2, matrix metalloproteinase-9, vascular endothelial growth factor, and basic fibroblast growth factor mRNA and protein levels. Overexpression of the LKB1 protein in human breast cancer is significantly associated with a decrease in microvessel density. Our results indicate that LKB1 plays a negative regulatory role in human breast cancer, a finding that may lead to a new therapeutic strategy. (Mol Cancer Res 2006;4(11):843–9)
Down Syndrome Candidate Region 1 Isoform 1 Mediates Angiogenesis through the Calcineurin-NFAT Pathway
Authors: Qin Liuliang , Zhao Dezheng , Liu Xin , Nagy Janice A. , Hoang Mien Van , Brown Lawrence F. , Dvorak Harold F. , Zeng Huiyan
Published: November 2006

Down syndrome candidate region 1 (DSCR1) is one of more than 50 genes located in a region of chromosome 21 that has been implicated in Down syndrome. DSCR1 can be expressed as four isoforms, one of which, isoform 4 (DSCR1-4), has recently been found to be strongly induced by vascular endothelial growth factor A (VEGF-A165) and to provide a negative feedback loop that inhibits VEGF-A165-induced endothelial cell proliferation in vitro and angiogenesis in vivo. We report here that another DSCR1 isoform, DSCR1-1L, is also up-regulated by VEGF-A165 in cultured endothelial cells and is strongly expressed in several types of pathologic angiogenesis in vivo. In contrast to DSCR1-4, the overexpression of DSCR1-1L induced the proliferation and activation of the transcription factor NFAT in cultured endothelial cells and promoted angiogenesis in Matrigel assays in vivo, even in the absence of VEGF-A. Similarly, small interfering RNAs specific for DSCR1-1L and DSCR1-4 had opposing inhibitory and stimulatory effects, respectively, on these same functions. DSCR1-4 is thought to inhibit angiogenesis by inactivating calcineurin, thereby preventing activation and nuclear translocation of NFAT, a key transcription factor. In contrast, DSCR1-1L, regulated by a different promoter than DSCR1-4, activates NFAT and its proangiogenic activity is inhibited by cyclosporin, an inhibitor of calcineurin. In sum, DSCR1-1L, unlike DSCR1-4, potently activates angiogenesis and could be an attractive target for antiangiogenesis therapy. (Mol Cancer Res 2006;4(11):811–20)
MUC1 Oncoprotein Functions in Activation of Fibroblast Growth Factor Receptor Signaling
Authors: Ren Jian , Raina Deepak , Chen Wen , Li Guilan , Huang Lei , Kufe Donald
Published: November 2006

Activation of the fibroblast growth factor (FGF) receptor 3 (FGFR3) has been linked to the development of human cancers by mechanisms that are not well understood. The MUC1 oncoprotein is aberrantly overexpressed by certain hematologic malignancies and most human carcinomas. The present studies show that MUC1 associates with FGFR3. Stimulation of cells with FGF1 increased the interaction between MUC1 and FGFR3. FGF1 stimulation also induced c-Src-dependent tyrosine phosphorylation of the MUC1 cytoplasmic domain on a YEKV motif. FGF1-induced tyrosine phosphorylation of MUC1 was associated with increased binding of MUC1 to β-catenin and targeting of MUC1 and β-catenin to the nucleus. FGF1 also induced binding of MUC1 to the heat shock protein 90 (HSP90) chaperone by a mechanism dependent on phosphorylation of the YEKV motif. Notably, β-catenin and HSP90 compete for binding to the MUC1 cytoplasmic domain, indicating that MUC1 forms mutually exclusive complexes with these proteins. The results also show that inhibition of HSP90 with geldanamycin or 17-(allylamino)-17-demethoxygeldanamycin attenuates FGF1-induced binding of MUC1 to HSP90 and targeting of MUC1 to the mitochondrial outer membrane. These findings indicate that FGF1 induces phosphorylation of MUC1 on YEKV and thereby activates two distinct pathways: (a) nuclear localization of MUC1 and β-catenin and (b) delivery of MUC1 to mitochondria by HSP90. (Mol Cancer Res 2006;4(11):873–83)
Ventilation and Its Control during Incremental Exercise in Obesity
Authors: Salvadori Alberto , Fanari Paolo , Tovaglieri Ilaria , Giacomotti Emanuela , Nibbio Ferruccio , Belardi Fabiola , Longhini Erminio
Published: November 2006

Background: In obesity, the addition of mass loading of the chest wall by adipose tissue decreases compliance, but its ventilation does not seem to be a limiting factor to physical performance. Plasma K+ and lactic acid are considered important determinants of ventilation during exercise. Obesity is characterized by insulin resistance. Objectives: The aim of this study was to assess ventilatory adaptations to sustained effort and the effects of lactic acid and potassium in young obese subjects. Methods: Twelve obese subjects with a body mass index of 40 (mean age 27 years, 6 males) and 12 normal subjects with a body mass index of 22 (aged 28 years, 6 males) performed a progressive cycloergometric test with increases of 20 W every 4 min to exhaustion while minute ventilation, oxygen consumption, carbon dioxide production, end-tidal oxygen pressure, and end-tidal carbon dioxide pressure were measured. Blood samples were collected at the end of every step to determine plasma K+. Lactic acid was measured at rest, 40, 80, 120 W and peak exercise (or only at peak exercise if <120 W). Before each exercise, we tested insulin sensitivity using the quantitative insulin sensitivity check index. Results: Obese subjects had lower insulin sensitivity (0.318 vs. 0.345, p < 0.01). Peak exercise was not significantly different between both groups (125 W in the obese group vs. 137 W in the control group), but the ventilatory threshold was at lower power output in the obese group compared to the controls (76 vs. 107 W, p < 0.05). Ventilation increased less in the obese group but oxygen saturation of hemoglobin remained within normal limits up to exhaustion in both groups. Ventilation was appropriate for the CO2 increase but less appropriate for the increased O2 consumption. Both K+ and lactic acid increased less in the obese group. Conclusions: In our obese subjects, ventilation was not a limiting factor during exercise. Its lower increase may be due, in addition to the characteristics of their chest walls, to insulin resistance which may limit the increase in lactic acid during effort, and to the hypertrophy of muscle fibers previously noted, which may be linked to a lower increase in plasma K+ during physical exercise.
Regulation of Thromboxane Receptor Trafficking Through the Prostacyclin Receptor in Vascular Smooth Muscle Cells
Authors: Wilson Stephen J. , Dowling Jennifer K. , Zhao Lei , Carnish Erin , Smyth Emer M.
Published: November 2006

Background—Prostacyclin (PGI2) and thromboxane (TxA2) effect disparate outcomes for atherogenesis and the response to vascular injury; PGI2, a vasodilator and inhibitor of platelet aggregation, limits the deleterious actions of TxA2, a vasoconstrictor and platelet activator. Dimerization of their G protein-coupled receptors, IP and TP, evokes a modified cellular response through which IP/TP counter-balance may be effected. We examined the consequence of IP/TP interaction for the regulatory pathways of both receptors.

Methods and Results—TPα overexpressed in HEK293 cells or expressed endogenously in aortic smooth muscle cells (ASMCs) was internalized after selective activation of either TP or IP. Homologous trafficking of TP was unaltered by coexpression of IP. Heterologous sequestration of TPα required the physical presence of activated IP, in transfected and native cells, but was independent of IP signaling to adenylyl cyclase. Reciprocal heterologous regulation of IP, via activated TP, was evident in both HEK293 cells and ASMCs. Homologous TP internalization led to receptor retention and degradation. In contrast, when internalization was IP-induced, TPα was recycled to the cell surface in coexpressing HEK293 cells, but not in ASMCs, in accord with the postendocytotic pathway of IP.

Conclusions—IP/TPα interaction permits reciprocal regulation of receptor endocytosis via the trafficking pathway determined by the activated dimeric partner.
Angiopoietin-Like Protein3 Regulates Plasma HDL Cholesterol Through Suppression of Endothelial Lipase
Authors: Shimamura Mitsuru , Matsuda Morihiro , Yasumo Hiroaki , Okazaki Mitsuyo , Fujimoto Kazunori , Kono Keita , Shimizugawa Tetsuya , Ando Yosuke , Koishi Ryuta , Kohama Takafumi , Sakai Naohiko , Kotani Kazuaki , Komuro Ryutaro , Ishida Tatsuo , Hirata Kenichi , Yamashita Shizuya , Furukawa Hidehiko , Shimomura Iichiro
Published: November 2006

Objectives—

A low level of high-density lipoprotein (HDL) in plasma has been recognized as an aspect of metabolic syndrome and as a crucial risk factor of cardiovascular events. However, the physiological regulation of plasma HDL levels has not been completely defined. Current studies aim to reveal the contribution of angiopoietin-like protein3 (angptl3), previously known as a plasma suppressor of lipoprotein lipase, to HDL metabolism.

Methods and Results—

Angptl3-deficient mice showed low plasma HDL cholesterol and HDL phospholipid (PL), and which were increased by ANGPTL3 supplementation via adenovirus. In vitro, ANGPTL3 inhibited the phospholipase activity of endothelial lipase (EL), which hydrolyzes HDL-PL and hence decreases plasma HDL levels, through a putative heparin-binding site in the N-terminal domain of ANGPTL3. Post-heparin plasma in Angptl3-knockout mice had higher phospholipase activity than did that in wild-type mice, suggesting that the activity of endogenous EL is elevated in Angptl3-deficient mice. Furthermore, we established an ELISA system for human ANGPTL3 and found that plasma ANGPTL3 levels significantly correlated with plasma HDL cholesterol and HDL-PL levels in human subjects.

Conclusions—

Angptl3 acts as an inhibitor of EL and may be involved in the regulation of plasma HDL cholesterol and HDL-PL levels in humans and rodents.
Vascular Endothelial Growth Factor Receptor 2 Plays a Role in the Activation of Aortic Endothelial Cells by Oxidized Phospholipids
Authors: Zimman Alejandro , Mouillesseaux Kevin P. , Le Thang , Gharavi Nima M. , Ryvkin Ann , Graeber Thomas G. , Chen Tom T. , Watson Andrew D. , Berliner Judith A.
Published: November 2006

Objective—

Previous studies have shown that oxidized products of PAPC (Ox-PAPC) regulate cell transcription of interleukin-8, LDL receptor, and tissue factor. This upregulation takes place in part through the activation of sterol regulatory element-binding protein (SREBP) and Erk 1/2. The present studies identify vascular endothelial growth factor receptor 2 (VEGFR2) as a major regulator in the activation of SREBP and Erk 1/2 in endothelial cells activated by Ox-PAPC.

Methods and Results—

Ox-PAPC induced the phosphorylation of VEGFR2 at Tyr
1175
in human aortic endothelial cells. Inhibitors and siRNA for VEGFR2 decreased the transcription of interleukin-8, LDL receptor, and tissue factor in response to Ox-PAPC and the activation of SREBP and Erk 1/2, which mediate this transcription. We provide evidence that the activation of VEGFR2 is rapid, sustained, and c-Src–dependent.

Conclusions—

These data point to a major role of VEGFR2 in endothelial regulation by oxidized phospholipids which accumulate in atherosclerotic lesions and apoptotic cells.
Lysophosphatidic Acid Induces Thrombogenic Activity Through Phosphatidylserine Exposure and Procoagulant Microvesicle Generation in Human Erythrocytes
Authors: Chung Seung-Min , Bae Ok-Nam , Lim Kyung-Min , Noh Ji-Yoon , Lee Moo-Yeol , Jung Yi-Sook , Chung Jin-Ho
Published: November 2006

Objective—

Although erythrocytes have been suggested to play a role in blood clotting, mediated through phosphatidylserine (PS) exposure and/or PS-bearing microvesicle generation, an endogenous substance that triggers the membrane alterations leading to a procoagulant activity in erythrocytes has not been reported. We now demonstrated that lysophosphatidic acid (LPA), an important lipid mediator in various pathophysiological processes, induces PS exposure and procoagulant microvesicle generation in erythrocytes, which represent a biological significance resulting in induction of thrombogenic activity.

Methods and Results—

In human erythrocytes, LPA treatment resulted in PS exposure on remnant cells and PS-bearing microvesicle generation in a concentration-dependent manner. Consistent with the microvesicle generation, scanning electron microscopic study revealed that LPA treatment induced surface changes, alteration of normal discocytic shape into echinocytes followed by spherocytes. Surprisingly, chelation of intracellular calcium did not affect LPA-induced PS exposure and microvesicle generation. On the other hand, protein kinase C (PKC) inhibitors significantly reduced PS exposure and microvesicle generation induced by LPA, reflecting the role of calcium-independent PKC. Activation of PKC was confirmed by Western blot analysis showing translocation of calcium-independent isoform, PKCζ, to erythrocyte membrane. The activity of flippase, which is important in the maintenance of membrane asymmetry, was also inhibited by LPA. Furthermore, LPA-exposed erythrocytes actually potentiated the thrombin generation as determined by prothrombinase assay and accelerated the coagulation process initiated by recombinant human tissue factor in plasma. The adherence of erythrocytes to endothelial cells, another important feature of thrombogenic process, was also stimulated by LPA treatment.

Conclusion—

These results suggested that LPA-exposed erythrocytes could make an important contribution to thrombosis mediated through PS exposure and procoagulant microvesicle generation.
Induction of Heat Shock Response Protects the Heart Against Atrial Fibrillation
Authors: Brundel Bianca J. J. M. , Shiroshita-Takeshita Akiko , Qi XiaoYan , Yeh Yung-Hsin , Chartier Denis , van Gelder Isabelle C. , Henning Robert H. , Kampinga Harm H. , Nattel Stanley
Published: November 2006

There is evidence suggesting that heat shock proteins (HSPs) may protect against clinical atrial fibrillation (AF). We evaluated the effect of HSP induction in an in vitro atrial cell line (HL-1) model of tachycardia remodeling and in tachypaced isolated canine atrial cardiomyocytes. We also evaluated the effect of HSP induction on in vivo AF promotion by atrial tachycardia-induced remodeling in dogs. Tachypacing (3 Hz) significantly and progressively reduced Ca
2+
transients and cell shortening of HL-1 myocytes over 4 hours. These reductions were prevented by HSP-inducing pretreatments: mild heat shock, geranylgeranylacetone (GGA), and transfection with human HSP27 or the phosphorylation-mimicking HSP27-DDD. However, treatment with HSP70 or the phosphorylation-deficient mutant HSP27-AAA failed to alter tachycardia-induced Ca
2+
transient and cell-shortening reductions, and downregulation (short interfering RNA) of HSP27 prevented GGA-mediated protection. Tachypacing (3 Hz) for 24 hours in vitro significantly reduced L-type Ca
2+
current and action potential duration in canine atrial cardiomyocytes; these effects were prevented when tachypacing was performed in cells exposed to GGA. In vivo treatment with GGA increased HSP expression and suppressed refractoriness abbreviation and AF promotion in dogs subjected to 1-week atrial tachycardia-induced remodeling. In conclusion, our findings indicate that (1) HSP induction protects against atrial tachycardia-induced remodeling, (2) the protective effect in HL-1 myocytes requires HSP27 induction and phosphorylation, and (3) the orally administered HSP inducer GGA protects against AF in a clinically relevant animal model. These findings advance our understanding of the biochemical determinants of AF and suggest the possibility that HSP induction may be an interesting novel approach to preventing clinical AF.
A Nuclear Receptor Corepressor–Dependent Pathway Mediates Suppression of Cytokine-Induced C-Reactive Protein Gene Expression by Liver X Receptor
Authors: Blaschke Florian , Takata Yasunori , Caglayan Evren , Collins Alan , Tontonoz Peter , Hsueh Willa A. , Tangirala Rajendra K.
Published: November 2006

C-reactive protein (CRP), the prototypical human acute phase protein, is an independent risk predictor of future cardiovascular events, both in healthy individuals and in patients with known cardiovascular disease. In addition, previous studies indicate that CRP might have direct proatherogenic properties. Ligand activation of the liver X receptor (LXR), a member of the nuclear hormone receptor superfamily, inhibits inflammatory gene expression in macrophages and attenuates the development of atherosclerosis in various animal models. We demonstrate herein that 2 synthetic LXR ligands, T0901317 and GW3965, inhibit interleukin-1β/interleukin-6–induced CRP mRNA and protein expression in human hepatocytes. Knockdown of LXRα/β by short interfering RNAs completely abolished the inhibitory effect of the LXR agonist T0901317 on cytokine-induced CRP gene transcription. Transient transfection experiments with 5′-deletion CRP promoter constructs identified a region from −125 to −256 relative to the initiation site that mediated the inhibitory effect of LXR ligands on CRP gene transcription. Depletion of the nuclear receptor corepressor by specific short interfering RNA increased cytokine-inducible CRP mRNA expression and promoter activity and reversed LXR ligand–mediated repression of CRP gene transcription. Chromatin immunoprecipitation assays indicated that nuclear receptor corepressor is present on the endogenous CRP promoter under basal conditions. Cytokine-induced clearance of nuclear receptor corepressor complexes was inhibited by LXR ligand treatment, maintaining the CRP gene in a repressed state. Finally, treatment of C57Bl6/J mice with LXR ligands attenuated lipopolysaccharide-induced mouse CRP and serum amyloid P component gene expression in the liver, whereas no effect was observed in LXRαβ knockout mice. Our observations identify a novel mechanism of inflammatory gene regulation by LXR ligands. Thus, inhibition of CRP expression by LXR agonists may provide a promising approach to impact initiation and progression of atherosclerosis.
Molecular Coupling of a Ca
2+
-Activated K
+
Channel to L-Type Ca
2+
Channels via α-Actinin2
Authors: Lu Ling , Zhang Qian , Timofeyev Valeriy , Zhang Zhao , Young J. Nilas , Shin Hee-Sup , Knowlton Anne A. , Chiamvimonvat Nipavan
Published: November 2006

Cytoskeletal proteins are known to sculpt the structural architecture of cells. However, their role as bridges linking the functional crosstalk of different ion channels is unknown. Here, we demonstrate that a small conductance Ca
2+
-activated K
+
channels (SK2 channel), present in a variety of cells, where they integrate changes in intracellular Ca
2+
concentration [Ca
2+
i
] with changes in K
+
conductance and membrane potential, associate with L-type Ca
2+
channels; Ca
v
1.3 and Ca
v
1.2 through a physical bridge, α-actinin2 in cardiac myocytes. SK2 channels do not physically interact with L-type Ca
2+
channels, instead, the 2 channels colocalize via their interaction with α-actinin2 cytoskeletal protein. The association of SK2 channel with α-actinin2 localizes the channel to the entry of external Ca
2+
source, which regulate the channel function. Furthermore, we demonstrated that the functions of SK2 channels in atrial myocytes are critically dependent on the normal expression of Ca
v
1.3 Ca
2+
channels. Null deletion of Ca
v
1.3 channel results in abnormal function of SK2 channel and prolongation of repolarization and atrial arrhythmias. Our study provides insight into the molecular mechanisms of the coupling of SK2 channel with voltage-gated Ca
2+
channel, and represents the first report linking the coupling of 2 different types of ion channels via cytoskeletal proteins.
Technology, Finance, and Dependency: Latin American Radical Political Economy in Retrospect
Authors: Vernengo Matias
Published: November 2006

The surge in academic work on globalization has made several of the topics dear to authors of the dependency school relevant once again. Therefore, a reconsideration of dependency theory seems to be appropriate. There are at least two approaches to dependency. This article analyzes critically their similarities, differences, and limitations, in particular regarding the role of technology and international finance in the explanation of center and periphery interactions. The evolution of the ideas on dependency in Latin America is evaluated. The reduced relevance of strict definitions of the technological division of labor, the theoretical problems caused by the effective industrialization of several countries in the periphery, the debt crisis, and the failure of the neoliberal agenda are also discussed. In the era of globalization and great transformations in the international economy, the “new” dependency seems to be financial in nature.
Marxian Microfoundations: Contribution or Detour?
Authors: Goldstein Jonathan P.
Published: November 2006

This article celebrates and critically examines the twenty-five-year productive, yet highly controversial, Marxian microfoundations (MM) literature. The contentious methodological debate over MM that is dominated by fundamentalist positions on both sides is evaluated and rejected. An alternative, centrist, methodological defense of MM is developed. Having established a methodological basis for MM, the micro contributions of the existing literature are evaluated in the following subject areas: methodology, accumulation and crisis, labor process and labor market segmentation, technical change, and class and exploitation. I conclude that although the MM literature has made significant contributions to strengthening Marxian arguments/propositions, there is room for improvement in the areas of integrating existing MM with common themes, improving modeling techniques, developing better linkages between micro and macro behaviors, expanding the analysis to neglected topics, and empirically verifying underlying assumptions.
Policies on Police Officer Domestic Violence: Prevalence and Specific Provisions Within Large Police Agencies
Authors: Lonsway Kimberly A.
Published: November 2006

Research was conducted to determine the prevalence and specific provisions of policies regarding officer-involved domestic violence. First, a national sample of 78 large police agencies was surveyed, and 23 agencies (29%) indicated that they had such a specific policy. However, a number of factors suggests that this estimate is probably artificially high. Second, a total of 22 policies was analyzed with a coding structure based on the International Association of Chiefs of Police (IACP) Model Policy. The policies varied widely in their scope, focus, and specific provisions. The most common elements were that a supervisor be immediately notified and that officers have a duty to report knowledge of domestic violence involving themselves or other employees. Most policies included very few of the provisions from the model developed by the IACP.
Police Culture and Young Offenders: The Effect of Legislative Change on Definitions of Crime and Delinquency
Authors: Schulenberg Jennifer L.
Published: November 2006

As of April 2003, Canada has new youth justice legislation that has implications for how police do their work in the areas of informal action (extrajudicial measures or sanctions). Because of legislative change, there exists a strong potential for challenges within the police culture's typifications and recipes for action in how police officers define a youth as a delinquent and an offense as serious. Using a mixed method–mixed model design and data from 202 semistructured interviews collected during 2002, this article explores the continuity and discontinuity in definitions between the police culture and the legislation. These are compared and contrasted to assess whether the nature of official responses to juvenile crime will differ in the new legislative environment. The results suggest that for legislative change to be effective in harmonizing police behavior, it must not only be represented in policies and procedures but also incorporated into the police culture.
Expression of a non–DNA-binding isoform of Helios induces T-cell lymphoma in mice
Authors: Zhang Zheng , Swindle C. Scott , Bates John T. , Ko Rose , Cotta Claudiu V. , Klug Christopher A.
Published: November 2006

Helios is a zinc-finger protein belonging to the Ikaros family of transcriptional regulators. It is expressed, along with Ikaros, throughout early stages of thymocyte development where it quantitatively associates with Ikaros through C-terminal zinc-finger domains that mediate heterodimerization between Ikaros family members. To understand the role of Helios in T-cell development, we used a retroviral vector to express full-length Helios or a Helios isoform that lacked the N-terminal DNA-binding domain in hematopoietic progenitor cells of reconstituted mice. Constitutive expression of full-length Helios resulted in an inhibition of T-cell development at the double-negative stage within the thymus. Although expression of the DNA-binding mutant of Helios did not contribute to developmental abnormalities at early times after transplantation, 60% of animals that expressed the Helios DNA-binding mutant developed an aggressive and transplantable T-cell lymphoma 4 to 10 months after transplantation. These results demonstrate a vital function for Helios in maintaining normal homeostasis of developing T cells and formally show that non–DNA-binding isoforms of Helios are lymphomagenic if aberrantly expressed within the T-cell lineage.
Granulocyte-stimulating factor and severe aplastic anemia: a survey by the European Group for Blood and Marrow Transplantation (EBMT)
Authors: Socie Gerard , Mary Jean-Yves , Schrezenmeier Hubert , Marsh Judith , Bacigalupo Andrea , Locasciulli Anna , Fuehrer Monica , Bekassy Albert , Tichelli Andre , Passweg Jakob
Published: November 2006

Previous studies suggested a link between the use of G-CSF and increased incidence of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) after immunosuppressive therapy (IST) for severe aplastic anemia (SAA). This European survey included 840 patients who received a first-line IST with (43%) or without (57%) G-CSF. The incidences of MDS/AML in patients who did or did not receive G-CSF were 10.9% and 5.8%, respectively. A significantly higher hazard (1.9) of MDS/AML was associated with use of G-CSF. Relapse of aplastic anemia was not associated with a worse outcome in patients who did not receive G-CSF as first therapy, whereas relapse was associated with a significantly worse outcome in those patients who received G-CSF. These results emphasize the necessity of the current European randomized trial comparing IST with or without G-CSF and to alert physicians that adding G-CSF to IST is currently not standard treatment for SAA.
Specific antibodies to moesin, a membrane-cytoskeleton linker protein, are frequently detected in patients with acquired aplastic anemia
Authors: Takamatsu Hiroyuki , Feng Xingmin , Chuhjo Tatsuya , Lu Xuzhang , Sugimori Chiharu , Okawa Katsuya , Yamamoto Miyuki , Iseki Shoichi , Nakao Shinji
Published: November 2006

To identify novel autoantibodies in acquired aplastic anemia (AA), we screened the sera of patients with AA possessing small populations of paroxysmal nocturnal hemoglobinuria (PNH)–type cells for the presence of antibodies (Abs) which recognize proteins derived from a leukemia cell line, UT-7. Immunoblotting using proteins derived from lysates or culture supernatants of UT-7 cells revealed the presence of IgG Abs specific to an 80-kDa protein. Peptide mass fingerprinting identified this 80-kDa protein as moesin. Enzyme-linked immunosorbent assay (ELISA) using recombinant moesin showed high titers of antimoesin Abs in 25 (37%) of 67 patients with AA. Moesin was secreted from several myeloid leukemia cell lines other than UT-7, such as OUN-1 and K562, as an exosomal protein. The presence of antimoesin Abs was significantly correlated with the presence of PNH-type cells and antidiazepam-binding inhibitor-related protein-1 (DRS-1) Abs. Patients with AA that did not show any of these 3 markers tended to respond poorly to immunosuppressive therapy. These findings suggest that a B-cell response to moesin, possibly derived from hematopoietic cells, frequently occurs in patients with AA and that detection of antimoesin Abs in combination with other markers may be useful in diagnosing immune pathophysiology in patients with AA.
A phase 2/3 multicenter randomized clinical trial of ABX-CBL versus ATG as secondary therapy for steroid-resistant acute graft-versus-host disease
Authors: MacMillan Margaret L. , Couriel Daniel , Weisdorf Daniel J. , Schwab Gisela , Havrilla Nancy , Fleming Thomas R. , Huang Saling , Roskos Lorin , Slavin Shimon , Shadduck Richard K. , DiPersio John , Territo Mary , Pavletic Steve , Linker Charles , Heslop Helen E. , Joachim Deeg H. , Blazar Bruce R.
Published: November 2006

Treatment for steroid-resistant acute graft-versus-host disease (GVHD) has had limited success. ABX-CBL is a hybridoma-generated murine IgM monoclonal antibody against the CD147 antigen, weakly expressed on human leukocytes and up-regulated on activated lymphocytes. A prospective, multicenter, open-label, randomized clinical trial comparing ABX-CBL to antithymocyte globulin (ATG) for treatment of steroid-resistant acute GVHD was conducted in 95 patients at 21 centers. Forty-eight patients received ABX-CBL daily for 14 consecutive days followed by up to 6 weeks of ABX-CBL twice weekly. Forty-seven patients received equine ATG, 30 mg/kg every other day for a total of 6 doses with additional courses as needed. By day 180, overall improvement was similar in the patients receiving ABX-CBL and in those receiving ATG (56% versus 57%, P = .91). Patient survival at 18 months was less favorable on ABX-CBL than on ATG (35% versus 45%), with the 95% confidence interval ruling out that ABX-CBL provides at least a 10.4% improvement. Data from this trial suggest that ABX-CBL does not offer an improvement over ATG in the treatment of acute steroid-resistant GVHD. This prospective, multicenter, randomized clinical trial for steroid-resistant acute GVHD serves as a model for future evaluation of new agents.
Regulation of protein synthesis by the heme-regulated eIF2α kinase: relevance to anemias
Authors: Chen Jane-Jane
Published: November 2006

During erythroid differentiation and maturation, it is critical that the 3 components of hemoglobin, α-globin, β-globin, and heme, are made in proper stoichiometry to form stable hemoglobin. Heme-regulated translation mediated by the heme-regulated inhibitor kinase (HRI) provides one major mechanism that ensures balanced synthesis of globins and heme. HRI phosphorylates the α-subunit of eukaryotic translational initiation factor 2 (eIF2α) in heme deficiency, thereby inhibiting protein synthesis globally. In this manner, HRI serves as a feedback inhibitor of globin synthesis by sensing the intracellular concentration of heme through its heme-binding domains. HRI is essential not only for the translational regulation of globins, but also for the survival of erythroid precursors in iron deficiency. Recently, the protective function of HRI has also been demonstrated in murine models of erythropoietic protoporphyria and β-thalassemia. In these 3 anemias, HRI is essential in determining red blood cell size, number, and hemoglobin content per cell. Translational regulation by HRI is critical to reduce excess synthesis of globin proteins or heme under nonoptimal disease states, and thus reduces the severity of these diseases. The protective role of HRI may be more common among red cell disorders.
Hlx homeobox transcription factor negatively regulates interferon-γ production in monokine-activated natural killer cells
Authors: Becknell Brian , Hughes Tiffany L. , Freud Aharon G. , Blaser Bradley W. , Yu Jianhua , Trotta Rossana , Mao Hsiaoyin C. , Caligiuri de Jesús Marie L. , Alghothani Mohamad , Benson Don M. , Lehman Amy , Jarjoura David , Perrotti Danilo , Bates Michael D. , Caligiuri Michael A.
Published: November 2006

Natural killer (NK) cells contribute to host immunity, including tumor surveillance, through the production of interferon gamma (IFN-γ). Although there is some knowledge about molecular mechanisms that induce IFN-γ in NK cells, considerably less is known about the mechanisms that reduce its expression. Here, we investigate the role of the Hlx transcription factor in IFN-γ production by NK cells. Hlx expression is induced in monokine-activated NK cells, but with delayed kinetics compared to IFN-γ. Ectopic Hlx expression decreases IFN-γ synthesis in primary human NK cells and IFN-γ promoter activity in an NK-like cell line. Hlx protein levels inversely correlate with those of STAT4, a requisite factor for optimal IFN-γ transcription. Mechanistically, we provide evidence indicating that Hlx overexpression accelerates dephosphorylation and proteasome-dependent degradation of the active Y693-phosphorylated form of STAT4. Thus, Hlx expression in activated NK cells temporally controls and limits the monokine-induced production of IFN-γ, in part through the targeted depletion of STAT4.
Celastrol, a novel triterpene, potentiates TNF-induced apoptosis and suppresses invasion of tumor cells by inhibiting NF-κB–regulated gene products and TAK1-mediated NF-κB activation
Authors: Sethi Gautam , Ahn Kwang Seok , Pandey Manoj K. , Aggarwal Bharat B.
Published: November 2006

Celastrol, a quinone methide triterpene derived from the medicinal plant Tripterygium wilfordii, has been used to treat chronic inflammatory and autoimmune diseases, but its mechanism is not well understood. Therefore, we investigated the effects of celastrol on cellular responses activated by TNF, a potent proinflammatory cytokine. Celastrol potentiated the apoptosis induced by TNF and chemotherapeutic agents and inhibited invasion, both regulated by NF-κB activation. We found that TNF induced the expression of gene products involved in antiapoptosis (IAP1, IAP2, Bcl-2, Bcl-XL, c-FLIP, and survivin), proliferation (cyclin D1 and COX-2), invasion (MMP-9), and angiogenesis (VEGF) and that celastrol treatment suppressed their expression. Because these gene products are regulated by NF-κB, we postulated that celastrol mediates its effects by modulating the NF-κB pathway. We found that celastrol suppressed both inducible and constitutive NF-κB activation. Celastrol was found to inhibit the TNF-induced activation of IκBα kinase, IκBα phosphorylation, IκBα degradation, p65 nuclear translocation and phosphorylation, and NF-κB–mediated reporter gene expression. Recent studies indicate that TNF-induced IKK activation requires activation of TAK1, and we indeed found that celastrol inhibited the TAK1-induced NF-κB activation. Overall, our results suggest that celastrol potentiates TNF-induced apoptosis and inhibits invasion through suppression of the NF-κB pathway.
Novel methods for secondary structure determination using low wavelength (VUV) circular dichroism spectroscopic data
Authors: Lees Jonathan G , Miles Andrew J , Janes Robert W , Wallace B A
Published: November 2006

Background

Circular Dichroism (CD) spectroscopy is a widely used method for studying protein structures in solution. Modern synchrotron radiation CD (SRCD) instruments have considerably higher photon fluxes than do conventional lab-based CD instruments, and hence have the ability to routinely measure CD data to much lower wavelengths. Recently a new reference dataset of SRCD spectra of proteins of known structure, designed to cover secondary structure and fold space, has been produced which includes low wavelength (vacuum ultraviolet – VUV) data. However, the existing algorithms used to calculate protein secondary structures from CD data have not been designed to take optimal advantage of the additional information in these low wavelength data.

Results

In this study, we have optimised secondary structure calculation methods based on the low wavelength CD data by examining existing algorithms and secondary structure assignment schemes, and then developing new methods which have produced clear improvements in prediction accuracy, especially for beta-sheet components. We have further shown that if precise measurements of protein concentrations, and therefore spectral magnitudes, are not available, the inclusion of the low wavelength data will significantly improve the analyses. However, we have also demonstrated that the new reference dataset, methods, and assignments can also improve the analyses of conventional circular dichroism data, even if the low wavelength data is not available.

Conclusion

VUV CD data include important information on protein structure which can be exploited with the algorithms and methodologies described.
Hyaluronan- and RNA-binding deubiquitinating enzymes of USP17 family members associated with cell viability
Authors: Shin Ju-Mi , Yoo Kyong-Jai , Kim Myung-Sun , Kim Dongku , Baek Kwang-Hyun
Published: November 2006

Background

Protein degradation by the ubiquitin system plays a crucial role in numerous cellular signaling pathways. Deubiquitination, a reversal of ubiquitination, has been recognized as an important regulatory step in the ubiquitin-dependent degradation pathway.

Results

While identifying putative ubiquitin specific protease (USP) enzymes that contain a conserved Asp (I) domain in humans, 4 USP17 subfamily members, highly homologous to DUB-3, have been found (USP17K, USP17L, USP17M, and USP17N), from human chorionic villi. Expression analysis showed that USP17 transcripts are highly expressed in the heart, liver, and pancreas and are expressed moderately in various human cancerous cell lines. Amino acid sequence analysis revealed that they contain the highly conserved Cys, His, and Asp domains which are responsible for the deubiquitinating activity. Biochemical enzyme assays indicated that they have deubiquitinating activity. Interestingly, the sequence analysis showed that these proteins, with exception of USP17N, contain the putative hyaluronan/RNA binding motifs, and cetylpyridinium chloride (CPC)-precipitation analysis confirmed the association between these proteins and intracellular hyaluronan and RNA.

Conclusion

Here, we report that the overexpression of these proteins, with exception of USP17N, leads to apoptosis, suggesting that the hyaluronan and RNA binding motifs in these enzymes play an important role in regulating signal transduction involved in cell death.