bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Nanotube Interconnects
Authors: Naeemi Azad , Meindl James D.
Published: January 2009

The performance and power dissipation of integrated circuits (IC) are largely affected by interconnects. Carbon nanotubes, which are rolls of one-atom-thick carbon sheets, show great potential in addressing some of the major interconnect challenges in future generations of technology, when copper conductivity will degrade substantially because of size effects. Some of the fascinating properties of carbon nanotubes include very large current conduction capacity, large electron mean free paths, high mechanical strength, and stability. In this article, the physical circuit models for carbon nanotubes are reviewed, and the potential performances of both single-wall carbon nanotube (SWNT) and multiwall carbon nanotube (MWNT) interconnects are benchmarked against their copper counterparts at a realistic operating temperature (100°C). The models capture various electron phonon scattering mechanisms and the dependency of quantum conductance on temperature and diameter. A hybrid system of copper/SWNTs/MWNTs offers the highest performance enhancement for interconnects.
Forensic Seismology and the Comprehensive Nuclear-Test-Ban Treaty
Authors: Bowers David , Selby Neil D.
Published: January 2009

One application of forensic seismology is to help verify compliance with the Comprehensive Nuclear-Test-Ban Treaty. One of the challenges facing the forensic seismologist is to discriminate between the many thousands of earthquakes of potential interest each year and potential Treaty violations (underground explosions). There are four main methods: (a) ratio of body- to surface-wave magnitudes, (b) ratio of high-frequency P to S energy, (c) model-based methods, and (d) source depth. Methods (a) and (b) have an empirical basis. The weakness of methods (a)–(c) is the lack of an equivalent elastic source for an underground explosion fired in the range of geological media found around the world. Reliable routine source-depth determination has proved difficult. However, experience gained in the past decade at identifying suspicious seismic sources suggests that although no single method works all of the time, intelligent and original application of complementary methods is usually sufficient to satisfactorily identify the source in question.
Radiocarbon and Soil Carbon Dynamics
Authors: Trumbore Susan
Published: January 2009

Research over the past several decades has clarified the mechanisms and timescales involved in stabilizing organic matter in soils, but we still lack process-based understanding sufficient for predicting how vulnerable soil carbon (C) is, given climatic or environmental change across a range of soil types and landscapes. Part of the problem is the emphasis on short-term studies and processes that dominate C balance at the point or soil profile scale, whereas other processes that dominate over longer timescales and larger spatial scales may actually be more important for determining the carbon balance of soils in a region. Radiocarbon is one of the only tools to study the dynamics of C in soils on decadal to millennial timescales. It provides a means for directly testing models of organic matter dynamics in ecosystems and, when measured in respired CO2or dissolved organic carbon (DOC), provides evidence of shifts in microbial metabolism. This review explores the application of this underutilized tool, with an emphasis on conceptual advances made using the state-factor approach and on detecting processes causing abrupt change in soil C stores.
Signaling pathway via TNF-α/NF-κB in intestinal epithelial cells may be directly involved in colitis-associated carcinogenesis
Authors: Onizawa Michio , Nagaishi Takashi , Kanai Takanori , Nagano Ken-ichi , Oshima Shigeru , Nemoto Yasuhiro , Yoshioka Atsushi , Totsuka Teruji , Okamoto Ryuichi , Nakamura Tetsuya , Sakamoto Naoya , Tsuchiya Kiichiro , Aoki Kazuhiro , Ohya Keiichi , Yagita Hideo , Watanabe Mamoru
Published: January 2009

Treatment with anti-TNF-α MAb has been accepted as a successful maintenance therapy for patients with inflammatory bowel diseases (IBD). Moreover, it has been recently reported that blockade of TNF receptor (TNFR) 1 signaling in infiltrating hematopoietic cells may prevent the development of colitis-associated cancer (CAC). However, it remains unclear whether the TNF-α signaling in epithelial cells is involved in the development of CAC. To investigate this, we studied the effects of anti-TNF-α MAb in an animal model of CAC by administration of azoxymethane (AOM) followed by sequential dextran sodium sulfate (DSS) ingestion. We observed that the NF-κB pathway is activated in colonic epithelia from DSS-administered mice in association with upregulation of TNFR2 rather than TNFR1. Immunoblot analysis also revealed that the TNFR2 upregulation accompanied by the NF-κB activation is further complicated in CAC tissues induced in AOM/DSS-administered mice compared with the nontumor area. Such NF-κB activity in the epithelial cells is significantly suppressed by the treatment of MP6-XT22, an anti-TNF-α MAb. Despite inability to reduce the severity of colitis, sequential administration of MP6-XT22 reduced the numbers and size of tumors in association with the NF-κB inactivation. Taken together, present studies suggest that the TNFR2 signaling in intestinal epithelial cells may be directly involved in the development of CAC with persistent colitis and imply that the maintenance therapy with anti-TNF-α MAb may prevent the development of CAC in patients with long-standing IBD.
Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon
Authors: Fei Guijun , Wang Yu-Zhong , Liu Sumei , Hu Hong-Zhen , Wang Guo-Du , Qu Mei-Hua , Wang Xi-Yu , Xia Yun , Sun Xiaohong , Bohn Laura M. , Cooke Helen J. , Wood Jackie D.
Published: January 2009

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current ( Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1–3000 nM, evoked increases in Iscin a concentration-dependent manner with an EC50of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1–3000 nM evoked increases in Iscin a concentration-dependent manner with an EC50of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Iscby lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1–3, or EP4receptors did not suppress stimulation of Iscby lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed ( P < 0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2receptor agonists increased basal Iscfollowed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles.
Lactobacillus reuteri ingestion prevents hyperexcitability of colonic DRG neurons induced by noxious stimuli
Authors: Ma Xuelian , Mao Yu-Kang , Wang Bingxian , Huizinga Jan D. , Bienenstock John , Kunze Wolfgang
Published: January 2009

Lactobacillus species ingestion can decrease autonomic responses and spinal fiber discharge to nociceptive colorectal distension (CRD), even in the absence of inflammation. The present study aimed to determine whether dorsal root ganglion (DRG) somas could be a locus where the antinociceptive probiotic may have an effect. Healthy rats were fed with Lactobacillus reuteri or vehicle control for 9 days whereupon they were anesthetized, and intermittent distal colonic CRD at 80 mmHg distension was either performed for 1 h or not. The animals were immediately euthanized and patch-clamp recordings taken after isolation and overnight culture from those DRG that projected to the distal colon. CRD decreased the threshold for action potential generation and increased the number of spikes discharged during a standard depolarizing test stimulus, and this effect was blocked by prior probiotic ingestion. The increase in excitability was paralleled by an increase in DRG capacitance, which was not altered by Lactobacillus reuteri ingestion. CRD did not increase tissue weight or myeloperoxidase activity. We suggest that the effects of CRD may have been caused by activity-dependent neurotransmission between DRG somas. CRD evoked increases in action potential upstroke speed, which suggests that it may also have led to augmentation of sodium channel conductances. Probiotic ingestion may have interfered with this hypothetical mechanism since it blocked the effect of CRD on the action potential.
Secretory effects of a luminal bitter tastant and expressions of bitter taste receptors, T2Rs, in the human and rat large intestine
Authors: Kaji Izumi , Karaki Shin-ichiro , Fukami Yasuyuki , Terasaki Masaki , Kuwahara Atsukazu
Published: January 2009

Taste transduction molecules, such as Gαgust, and taste receptor families for bitter [taste receptor type 2 (T2R)], sweet, and umami, have previously been identified in taste buds and the gastrointestinal (GI) tract; however, their physiological functions in GI tissues are still unclear. Here, we investigated the physiological function and expression of T2R in human and rat large intestine using various physiological and molecular biological techniques. To study the physiological function of T2R, the effect of a bitter compound, 6- n-propyl-2-thiouracil (6-PTU), on transepithelial ion transport was investigated using the Ussing chamber technique. In mucosal-submucosal preparations, mucosal 6-PTU evoked Cl−and HCO3−secretions in a concentration-dependent manner. In rat middle colon, levels of 6-PTU-evoked anion secretion were higher than in distal colon, but there was no such difference in human large intestine. The response to 6-PTU was greatly reduced by piroxicam, but not by tetrodotoxin. Additionally, prostaglandin E2concentration-dependently potentiated the response to 6-PTU. Transcripts of multiple T2Rs (putative 6-PTU receptors) were detected in both human and rat colonic mucosa by RT-PCR. In conclusion, these results suggest that the T2R ligand, 6-PTU, evokes anion secretion, and such response is regulated by prostaglandins. This luminal bitter sensing mechanism may be important for host defense in the GI tract.
Tissue factor-dependent coagulation contributes to α-naphthylisothiocyanate-induced cholestatic liver injury in mice
Authors: Luyendyk James P. , Cantor Glenn H. , Kirchhofer Daniel , Mackman Nigel , Copple Bryan L. , Wang Ruipeng
Published: January 2009

Separation of concentrated bile acids from hepatic parenchymal cells is a key function of the bile duct epithelial cells (BDECs) that form intrahepatic bile ducts. Using coimmunostaining, we found that tissue factor (TF), the principal activator of coagulation, colocalized with cytokeratin 19, a marker of BDECs in the adult mouse liver. BDEC injury induced by xenobiotics such as α-naphthylisothiocyanate (ANIT) causes cholestasis, inflammation, and hepatocellular injury. We tested the hypothesis that acute ANIT-induced cholestatic hepatitis is associated with TF-dependent activation of coagulation and determined the role of TF in ANIT hepatotoxicity. Treatment of mice with ANIT (60 mg/kg) caused multifocal hepatic necrosis and significantly increased serum biomarkers of cholestasis and hepatic parenchymal cell injury. ANIT treatment also significantly increased liver TF expression and activity. ANIT-induced activation of the coagulation cascade was shown by increased plasma thrombin-antithrombin levels and significant deposition of fibrin within the necrotic foci. ANIT-induced coagulation and liver injury were reduced in low-TF mice, which express 1% of normal TF levels. The results indicate that ANIT-induced liver injury is accompanied by TF-dependent activation of the coagulation cascade and that TF contributes to the progression of injury during acute cholestatic hepatitis.
Delineating the signals by which repetitive deformation stimulates intestinal epithelial migration across fibronectin
Authors: Gayer Christopher P. , Chaturvedi Lakshmi S. , Wang Shouye , Alston Brittany , Flanigan Thomas L. , Basson Marc D.
Published: January 2009

Repetitive strain stimulates intestinal epithelial migration across fibronectin via focal adhesion kinase (FAK), Src, and extracellular signal-related kinase (ERK) although how these signals act and interact remains unclear. We hypothesized that PI3K is central to this pathway. We subjected Caco-2 and intestinal epithelial cell-6 cells to 10 cycles/min deformation on flexible fibronectin-coated membranes, assayed migration by wound closure, and signaling by immunoblots. Strain stimulated PI3K, AKT, glycogen synthase kinase (GSK), and p38 phosphorylation. Blocking each kinase prevented strain stimulation of migration. Blocking PI3K prevented strain-stimulated ERK and p38 phosphorylation. Blocking AKT did not. Downstream, blocking PI3K, AKT, or ERK inhibited strain-induced GSK-Ser9 phosphorylation. Upstream of AKT, reducing FAK or Rac1 by siRNA blocked strain-stimulated AKT phosphorylation, but inhibiting Src by PP2 or siRNA did not. Transfection with FAK point mutants at Tyr397, Tyr576/577, or Tyr925 demonstrated that only FAK925 phosphorylation is required for strain-stimulated AKT phosphorylation. Myosin light chain activation by strain required FAK, Rac1, PI3K, AKT, GSK, and ERK but not Src or p38. Finally, blebbistatin, a nonmuscle myosin II inhibitor, blocked the motogenic effect of strain downstream of myosin light chain. Thus strain stimulates intestinal epithelial migration across fibronectin by a complex pathway including Src, FAK, Rac1, PI3K, AKT, GSK, ERK, p38, myosin light chain, and myosin II.
Longevity is associated with increased vascular resistance to high glucose-induced oxidative stress and inflammatory gene expression in Peromyscus leucopus
Authors: Labinskyy Nazar , Mukhopadhyay Partha , Toth Janos , Szalai Gabor , Veres Monika , Losonczy Gyorgy , Pinto John T. , Pacher Pal , Ballabh Praveen , Podlutsky Andrej , Austad Steven N. , Csiszar Anna , Ungvari Zoltan
Published: January 2009

Vascular aging is characterized by increased oxidative stress and proinflammatory phenotypic alterations. Metabolic stress, such as hyperglycemia in diabetes, is known to increase the production of ROS and promote inflammatory gene expression, accelerating vascular aging. The oxidative stress hypothesis of aging predicts that vascular cells of long-lived species exhibit lower steady-state production of ROS and/or superior resistance to the prooxidant effects of metabolic stress. We tested this hypothesis using two taxonomically related rodents, the white-footed mouse ( Peromyscus leucopus) and the house mouse ( Mus musculus), which show a more than twofold difference in maximum lifespan potential (8.2 and 3.5 yr, respectively). We compared interspecies differences in steady-state and high glucose (HG; 30 mmol/l)-induced production of O2•− and H2O2, endothelial function, mitochondrial ROS generation, and inflammatory gene expression in cultured aortic segments. In P. leucopus aortas, steady-state endothelial O2•− and H2O2 production and ROS generation by mitochondria were less than in M. musculus vessels. Furthermore, vessels of P. leucopus were more resistant to the prooxidant effects of HG. Primary fibroblasts from P. leucopus also exhibited less steady-state and HG-induced ROS production than M. musculus cells. In M. musculus arteries, HG elicited significant upregulation of inflammatory markers (TNF-α, IL-6, ICAM-1, VCAM, and monocyte chemoattractant protein-1). In contrast, the proinflammatory effects of HG were blunted in P. leucopus vessels. Thus, increased life span potential in P. leucopus is associated with decreased cellular ROS generation and increased resistance to prooxidant and proinflammatory effects of metabolic stress, which accord with predictions of the oxidative stress hypothesis of aging.
Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans
Authors: Kjeld Thomas , Pott Frank C. , Secher Niels H.
Published: January 2009

The diving response is initiated by apnea and facial immersion in cold water and includes, besides bradycardia, peripheral vasoconstriction, while cerebral perfusion may be enhanced. This study evaluated whether facial immersion in 10°C water has an independent influence on cerebral perfusion evaluated as the middle cerebral artery mean flow velocity (MCA Vmean) during exercise in nine male subjects. At rest, a breath hold of maximum duration increased the arterial carbon dioxide tension (PaCO2) from 4.2 to 6.7 kPa and MCA Vmean from 37 to 103 cm/s (mean; ∼178%; P < 0.001). Similarly, during 100-W exercise, a breath hold increased PaCO2 from 5.9 to 8.2 kPa ( P < 0.001) and MCA Vmean from 55 to 113 cm/s (∼105%), and facial immersion further increased MCA Vmean to 122 cm/s (∼88%; both P < 0.001). MCA Vmean also increased during 180-W exercise (from 47 to 53 cm/s), and this increment became larger with facial immersion (76 cm/s, ∼62%; P < 0.001), although PaCO2 did not significantly change. These results indicate that a breath hold diverts blood toward the brain with a >100% increase in MCA Vmean, largely because PaCO2 increases, but the increase in MCA Vmean becomes larger when combined with facial immersion in cold water independent of PaCO2.
Short oxygen prebreathe periods reduce or prevent severe decompression sickness in a 70-kg swine saturation model
Authors: Mahon R. T. , Dainer H. M. , Gibellato M. G. , Soutiere S. E.
Published: January 2009

Disabled submarine (DISSUB) survivors are expected to achieve saturation with inert gas. However, rescue procedures may not accommodate staged decompression, raising the potential for severe decompression sickness (DCS). Alternatives to standard recompression therapy are needed. It has been demonstrated in humans that isobaric oxygen “prebreathing” (OPB) can accelerate decompression in a DISSUB scenario. In-70 kg swine saturated at 2.82 atm absolute (ATA), 1 h of OPB eliminated death and reduced severe DCS. We hypothesized that even shorter periods (<1 h) of OPB before no-stop decompression from saturation at 2.82 ATA could reduce the incidence of DCS in a large animal model. Catheterized Yorkshire swine (68.8 ± 1.7 kg) in individual Plexiglas boxes within a large animal hyperbaric chamber were compressed to 2.82 ATA for 22 h. Following saturation and while still at depth, breathing gas was switched to >95% O2for 45 min (OPB45), 15 min (OPB15), or 5 min (OPB05) of OPB, or no OPB (control). The chamber was then decompressed without stops (0.91 ATA/min). Observers then entered the chamber and recorded signs of DCS for 2 h. All OPB periods significantly reduced the risk of developing type II DCS. OPB45eliminated severe DCS. Controls had a 2.5 times greater risk of developing type II DCS than OPB05( P = 0.016). OPB45and OPB15significantly reduced type I DCS compared with controls. These results support the potential of OPB as an alternative to staged decompression and that OPB could be expected to improve outcome in a DISSUB rescue scenario.
Effects of hyperbaric gases on membrane nanostructure and function in neurons
Authors: D'Agostino Dominic P. , Colomb Denis G. , Dean Jay B.
Published: January 2009

This mini-review summarizes current ideas of how hyperbaric gases (>1–10 atmospheres absolute) affect neuronal mechanisms of excitability through molecular interaction with membrane components. The dynamic nature of the lipid bilayer, its resident proteins, and the underlying cytoskeleton make each respective nanostructure a potential target for modulation by hyperbaric gases. Depending on the composition of the gas mixture, the relative concentrations of O2and inert gas, and total barometric pressure, the net effect of a particular gas on the cell membrane will be determined by the gas' 1) lipid solubility, 2) ability to oxidize lipids and proteins (O2), and 3) capacity, in the compressed state, to generate localized shear and strain forces between various nanostructures. A change in the properties of any one membrane component is anticipated to change conductance of membrane-spanning ion channels and thus neuronal function.
Chronic NHE-1 blockade induces an antiapoptotic effect in the hypertrophied heart
Authors: Garciarena Carolina D. , Caldiz Claudia I. , Portiansky Enrique L. , Chiappe de Cingolani Gladys E. , Ennis Irene L.
Published: January 2009

Na+/H+ exchanger (NHE-1) inhibition was demonstrated to induce the regression of cardiac hypertrophy (CH) in several experimental models and to inhibit mitochondrial death pathway in “in-vitro” experiments. Since recent reports show that NHE-1 inhibition delays the transition from CH to failure, and apoptosis plays a key role in this process, we investigated the effect of chronic treatment with the NHE-1 blocker cariporide on CH and apoptosis in the SHR. One month of cariporide treatment (30 mg·kg−1·day−1) induced the regression of CH (cardiomyocyte cross-sectional area: 468 ± 20 vs. 285 ± 9 μm2 in untreated and cariporide-treated spontaneously hypertensive rats; P < 0.05). Apoptosis was assessed by TUNEL staining, the expression of Bcl-2, Bax, and activation of caspase-3 and PARP-1 by immunoblot. Cariporide treatment decreased the TUNEL-positive cells, the Bax-to-Bcl-2 ratio (3.16 ± 0.32 vs. 1.70 ± 0.17, untreated and cariporide-treated, respectively; P < 0.05); caspase-3 and PARP-1 activation (465 ± 62 vs. 260 ± 22 and 2,239 ± 62 vs. 1,683 ± 85 AU, untreated and cariporide-treated, respectively; P < 0.05). Angiotensin II, a growth factor and apoptotic stimulus, was used to induce O2− production that activated the ERK1/2-p90RSK pathway, increasing NHE-1 phosphorylation. These effects were prevented by losartan, N-(2-mercaptopropionyl)-glycine, and cariporide. In conclusion, we present data demonstrating that chronic NHE-1 inhibition with cariporide decreases both hypertrophy and apoptosis susceptibility in the spontaneously hypertensive rat heart. The antiapoptotic effect would be the consequence of two different actions of cariporide: the prevention of cytosolic Na+ and Ca2+ overload due to the inhibition of the sarcolemmal NHE-1 and a direct mitochondrial effect preventing mitochondrial permeability transition pore opening.
Regulatory Role of G Protein–Coupled Estrogen Receptor for Vascular Function and Obesity
Authors: Haas Elvira , Bhattacharya Indranil , Brailoiu Eugen , Damjanović Marlen , Brailoiu G. Cristina , Gao Xin , Mueller-Guerre Laurence , Marjon Nicole A. , Gut André , Minotti Roberta , Meyer Matthias R. , Amann Kerstin , Ammann Emerita , Perez-Dominguez Ana , Genoni Michele , Clegg Deborah J. , Dun Nae J. , Resta Thomas C. , Prossnitz Eric R. , Barton Matthias
Published: January 2009

We found that the selective stimulation of the intracellular, transmembrane G protein–coupled estrogen receptor (GPER), also known as GPR30, acutely lowers blood pressure after infusion in normotensive rats and dilates both rodent and human arterial blood vessels. Stimulation of GPER blocks vasoconstrictor-induced changes in intracellular calcium concentrations and vascular tone, as well as serum-stimulated cell proliferation of human vascular smooth muscle cells. Deletion of the GPER gene in mice abrogates vascular effects of GPER activation and is associated with visceral obesity. These findings suggest novel roles for GPER in protecting from cardiovascular disease and obesity.
Genetic Variation in the Lymphotoxin-Alpha Pathway and the Risk of Ischemic Stroke in European Populations
Authors: Freilinger Tobias , Bevan Steve , Ripke Stephan , Gschwendtner Andreas , Lichtner Peter , Müller-Myhsok Bertram , Wichmann H. -Erich , Markus Hugh S. , Meitinger Thomas , Dichgans Martin
Published: January 2009

Background and Purpose—

Several genes involved in the lymphotoxin-α cascade (
LTA
,
LGALS2
, and
PSMA6
) have been linked with the risk of myocardial infarction. Here, we present a comprehensive analysis of these genes in patients with ischemic stroke (IS).

Methods—

Twenty-three single nucleotide polymorphisms (SNPs) from
LTA
,
LGALS2
, and
PSMA6
were genotyped in 601 German IS patients and 736 matched controls. SNPs and haplotypes were tested for association with overall IS, large vessel stroke, and cardioembolic stroke. Significant associations were replicated in an independent sample of 843 IS cases and 933 controls from the UK.

Results—

Only one SNP (rs1048990 in
PSMA6
) showed association with overall IS, but this was not replicated in the UK sample. Three SNPs showed significant associations with stroke subtypes (
P
<0.05), but none of these associations could be replicated in the UK population.

Conclusions—

Genetic variation in the lymphotoxin-α cascade (
LTA
,
LGALS2
, and
PSMA6
) is not a major risk factor for IS.
Chronic Kidney Disease and Clinical Outcome in Patients With Acute Stroke
Authors: Yahalom Gilad , Schwartz Roseline , Schwammenthal Yvonne , Merzeliak Oleg , Toashi Maya , Orion David , Sela Ben-Ami , Tanne David
Published: January 2009

Background and Purpose—

Chronic kidney disease (CKD) is increasingly recognized as an independent risk factor for cardiovascular disease and stroke. Our aim was to examine the association between estimated glomerular filtration rate (GFR) and stroke outcome and to assess whether CKD and its severity affect stroke outcome in a large cohort of unselected patients with acute stroke.

Methods—

We examined the association between baseline estimated GFR and CKD and 1-year outcomes in 821 consecutive patients with acute stroke (ischemic or hemorrhagic). GFR was estimated by 2 methods: the Modification of Diet in Renal Disease and the Mayo Clinic quadratic equation. An estimated GFR rate ≤60 mL/min/1.73 m
2
defined CKD.

Results—

Odds ratios (95% CI) for death across levels of estimated GFR based on both equations were estimated. CKD was present in 36% (n=291) of patients based on the Modification of Diet in Renal Disease equation and 18% (n=147) based on the Mayo Clinic equation. The adjusted ORs for mortality after 1-year based on the Modification of Diet in Renal Disease equation were 0.7 (95% CI, 0.4 to 1.2) associated with GFR 45 to 60 and 3.2 (1.7 to 6.4) associated with GFR 15 to 44 as compared with GFR >60 mL/min/1.73 m
2
, whereas those based on the Mayo Clinic equation were 2.3 (1.1 to 4.7) and 3.3 (1.6 to 7.1), respectively. The adjusted ORs for Barthel Index ≤75 or death after 1 year were 0.8 (0.5 to 1.5) and 2.1 (0.9 to 4.8) by the Modification of Diet in Renal Disease equation and 1.9 (0.8 to 4.4) and 3.9 (1.5 to 11.0) by the Mayo Clinic equation, respectively.

Conclusions—

CKD is a strong independent predictor of mortality and poor outcome in patients with acute stroke. The estimation of the prevalence of CKD and of the GFR cutoffs associated with poor outcome depend on the equation used to estimate GFR.
Estimating the Long-Term Costs Of Ischemic and Hemorrhagic Stroke for Australia
Authors: Cadilhac Dominique A. , Carter Rob , Thrift Amanda G. , Dewey Helen M.
Published: January 2009

Background and Purpose—

Stroke is associated with considerable societal costs. Cost-of-illness studies have been undertaken to estimate lifetime costs; most incorporating data up to 12 months after stroke. Costs of stroke, incorporating data collected up to 12 months, have previously been reported from the North East Melbourne Stroke Incidence Study (NEMESIS). NEMESIS now has patient-level resource use data for 5 years. We aimed to recalculate the long-term resource utilization of first-ever stroke patients and compare these to previous estimates obtained using data collected to 12 months.

Methods—

Population structure, life expectancy, and unit prices within the original cost-of-illness models were updated from 1997 to 2004. New Australian stroke survival and recurrence data up to 10 years were incorporated, as well as cross-sectional resource utilization data at 3, 4, and 5 years from NEMESIS. To enable comparisons, 1997 costs were inflated to 2004 prices and discounting was standardized.

Results—

In 2004, 27 291 ischemic stroke (IS) and 4291 intracerebral hemorrhagic stroke (ICH) first-ever events were estimated. Average annual resource use after 12 months was AU$6022 for IS and AU$3977 for ICH. This is greater than the 1997 estimates for IS (AU$4848) and less than those for ICH (previously AU$10 692). The recalculated average lifetime costs per first-ever case differed for IS (AU$57 106 versus AU$52 855 [1997]), but differed more for ICH (AU$49 995 versus AU$92 308 [1997]).

Conclusion—

Basing lifetime cost estimates on short-term data overestimated the costs for ICH and underestimated those for IS. Patterns of resource use varied by stroke subtype and, overall, the societal cost impact was large.
May-Thurner Syndrome in Patients With Cryptogenic Stroke and Patent Foramen Ovale
Authors: Kiernan Thomas J. , Yan Bryan P. , Cubeddu Roberto J. , Rengifo-Moreno Pablo , Gupta Vishal , Inglessis Ignacio , Ning MingMing , Demirjian Zareh N. , Jaff Michael R. , Buonanno Ferdinando S. , Schainfeld Robert M. , Palacios Igor F.
Published: January 2009

Background and Purpose—

We aimed to investigate the incidence of May-Thurner syndrome in patients with cryptogenic stroke with patent foramen ovale.

Methods—

This was a retrospective study. All consecutive patients with cryptogenic stroke having undergone patent foramen ovale closure from January 1, 2002, to December 31, 2007, at our institute were included in this study. Pelvic magnetic resonance venography studies of all patients were reviewed to determine if features of May-Thurner syndrome were present. Medical records and invasive venography studies of all patients were reviewed when available. All patients with May-Thurner syndrome features on magnetic resonance venography were reviewed by a vascular medicine specialist to define any previous incidence of deep vein thrombosis or any signs of chronic venous insufficiency. All patients also had lower limb venous duplex performed to rule out lower limb venous thrombosis.

Results—

A total of 470 patients from January 1, 2002, until December 31, 2007, with cryptogenic stroke underwent patent foramen ovale closure at our institute. Thirty patients (6.3%) had features consistent with May-Thurner syndrome on magnetic resonance venography. These patients were predominantly female (80%) with a mean age of 43.6±11.9 years. Twelve patients (40%) had abnormalities in their laboratory thrombophilia evaluation and 13 females (54.1%) were taking hormone-related birth control pills. Only 2 patients had a history and signs of chronic venous insufficiency. All patent foramen ovales demonstrated right-to-left shunting on transesophageal echocardiography. Atrial septal aneurysms/hypermobile atrial septa were present in 70% of patients with May-Thurner syndrome.

Conclusion—

May-Thurner syndrome has an important clinical association with cryptogenic stroke and patent foramen ovale.
Arterial Wall Enhancement Overlying Carotid Plaque on CT Angiography Correlates With Symptoms in Patients With High Grade Stenosis
Authors: Romero Javier M. , Babiarz Lukasz S. , Forero N. Paola , Murphy Erin K. , Schaefer Pamela W. , Gonzalez R. Gilberto , Lev Michael H.
Published: January 2009

Background and Purpose—

The degree of internal carotid artery (ICA) stenosis is an established primary risk factor for embolic stroke. Recent publications suggest that inflammatory features may also play an important role. Our purpose was to correlate acute neurological symptoms with either carotid artery wall enhancement or plaque calcification, on axial CT angiographic source images (CTA-SI) of patients with severe (≥70%) ICA stenosis.

Methods—

75 consecutive patients with ≥70% ICA stenosis on CTA-SI were identified. Each case was classified as symptomatic (n=37) or asymptomatic (n=38), and as having either calcified or noncalcified plaque. The latter group was stratified into those with versus without arterial wall enhancement, measured in absolute and relative Hounsfield Units (HU).

Results—

Calcified plaque was present in 39% (15/38) of the symptomatic patients and in 62% (23/37) of the asymptomatic patients (
P
=0.065). Of the 37 patients without calcified plaque, carotid wall enhancement was observed in 83% (19/23) of the symptomatic, but only in 57% (8/14) of the asymptomatic patients (
P
=0.041). When the “calcified plaque” and “no carotid wall enhancement” groups were pooled, versus the “carotid wall enhancement” group, enhancement was more likely in symptomatic patients (OR 3.625, CI 95% 1.3229 to 9.93,
P
=0.01 Fisher Exact test).

Conclusions—

In patients with severe ICA stenosis, additional stratification of stroke risk may be possible based on the presence of carotid wall enhancement on CTA-SI. Patients with carotid wall enhancement are more likely to be symptomatic, compared to those with either calcified plaque or no enhancement.
Brain Lesions in Cerebral Venous Sinus Thrombosis
Authors: Zubkov Alexander Y. , McBane Robert D. , Brown Robert D. , Rabinstein Alejandro A.
Published: January 2009

Background and Purpose—

Analyze the relationship between the location and extent of sinus thrombosis and presence and severity of brain lesions.

Methods—

Retrospective chart and neuroimaging review of patients with documented CVST. A CVST score was devised to quantify the extent of cerebral venous sinus thrombosis.

Results—

Nineteen of 56 (34%) patients had brain lesions. The extent of sinus thrombus was associated with increased risk of brain lesions (CVST score 1.9 among patients without brain lesions versus 3.1 in those with lesions;
P
=0.006). Age, sex, and acquired or hereditary thrombophilias were not associated with the risk of parenchymal lesions. Functional outcomes were favorable even in patients with extensive CVST and parenchymal lesions at presentation.

Conclusions—

The extent of the sinus involvement correlates with the risk of brain lesions in patients with CVST, but additional factors might also contribute to their occurrence.
Ice-Cold Saline for the Induction of Mild Hypothermia in Patients With Acute Ischemic Stroke
Authors: Kollmar Rainer , Schellinger Peter D. , Steigleder Tobias , Köhrmann Martin , Schwab Stefan
Published: January 2009

Background and Purpose—

Neuroprotective effects of induced hypothermia depend on its time point of initiation after acute brain injury. Preliminary studies in cardiac arrest patients indicate that rapid infusion of ice cold saline (ICS) is safe and effective for induction of hypothermia. We investigated its use in patients with acute ischemic stroke (AIS).

Methods—

Patients (n=10) with AIS were included within 3 hours after symptom onset. After cranial CT, they were treated—if indicated—with rt-PA. ICS of 4°C (25 mL/kg body weight) was administered via peripheral intravenous lines. Patients received buspirone/pethidine to prevent and treat shivering. After infusion of the target volume of ICS, no further efforts were made to maintain hypothermia by other methods.

Results—

Ten patients with a median National Institutes of Health Stroke Scale (NIHSS) score of 5.5 (range 4 to 12) on admission were included into the study. Nine patients were treated with thrombolysis within a time window of 104±25 minutes. A mean amount of 2163±256 mL ICS was infused 17±11 minutes after rt-PA infusion had started. Tympanic temperature dropped significantly by a maximum of 1.6±0.3°C (
P
<0.005) at 52±16 minutes after ICS was started. The procedure was well tolerated. The NIHSS score improved significantly to a median of 1 (range 1 to 15) at discharge compared to admission (
P
<0.02).

Conclusions—

This pilot study suggests that rapid ICS infusions in combination with pethidine and buspirone lower the body temperature significantly without major side effects.
Apoptotic Mechanisms After Cerebral Ischemia
Authors: Broughton Brad R.S. , Reutens David C. , Sobey Christopher G.
Published: January 2009

Background and Purpose—

Traditionally, cell death after cerebral ischemia was considered to be exclusively necrotic in nature, but research over the past decade has revealed that after a stroke, many neurons in the ischemic penumbra will undergo apoptosis.

Summary of Review—

This brief review provides a general overview and update of various signaling pathways in the development of apoptosis in ischemic lesions. Cerebral ischemia triggers two general pathways of apoptosis: the intrinsic pathway, originating from mitochondrial release of cytochrome
c
and associated stimulation of caspase-3; and the extrinsic pathway, originating from the activation of cell surface death receptors, resulting in the stimulation of caspase-8. Although many of the key apoptotic proteins have been identified, our understanding of the complex underlying mechanisms remains poor and hence treatment of stroke patients by manipulating apoptotic pathways remains a daunting task. However, recent advances in the field have helped broaden our knowledge of apoptosis after cerebral ischemia. Further to the simplistic concept that stroke-induced apoptosis occurs predominantly in neurons and is caspase-dependent, accumulating evidence now indicates that apoptosis is prevalent in nonneuronal cells and that caspase-independent mechanisms also play a key role.

Conclusions—

Although the ischemic penumbra is under threat of infarction, it is potentially salvageable and thus represents an opportunity for therapeutic intervention.
Would Self-Expanding Stent Occlude Middle Cerebral Artery Perforators?
Authors: Leung Thomas W. , Yu Simon C.H. , Lam Wynnie W.M. , Chan Anne Y.Y. , Lau Alexander Y.L. , Wong Lawrence K.S.
Published: January 2009

Background and Purpose—

A major concern of intracranial stenting is perforator infarction. It is unclear whether the sustained radial force of a self-expanding stent or subsequent stent restenosis would cause late occlusion of perforators.

Methods—

We compared the baseline and poststent (≥4 months) MRI scans of patients who underwent self-expanding stenting for recurrent ischemic symptoms attributed to a MCA stenosis ≥60%. New infarcts in the ipsilateral striatocapsular region were recorded.

Results—

MCA stenting was technically successful in 23 of 24 recruited patients. No new perforator territory infarct was found in follow-up MRI scans of all recruited patients. Postoperatively, all patients reported no further TIA or stroke over a median follow-up of 15 months.

Conclusions—

The use of a self-expanding stent in patients with high-grade MCA stenosis may not pose a major risk to the perforators.
The Effectiveness of the Bobath Concept in Stroke Rehabilitation
Authors: Kollen Boudewijn J. , Lennon Sheila , Lyons Bernadette , Wheatley-Smith Laura , Scheper Mark , Buurke Jaap H. , Halfens Jos , Geurts Alexander C.H. , Kwakkel Gert
Published: January 2009

Background and Purpose—

In the Western world, the Bobath Concept or neurodevelopmental treatment is the most popular treatment approach used in stroke rehabilitation, yet the superiority of the Bobath Concept as the optimal type of treatment has not been established. This systematic review of randomized, controlled trials aimed to evaluate the available evidence for the effectiveness of the Bobath Concept in stroke rehabilitation.

Method—

A systematic literature search was conducted in the bibliographic databases MEDLINE and CENTRAL (March 2008) and by screening the references of selected publications (including reviews). Studies in which the effects of the Bobath Concept were investigated were classified into the following domains: sensorimotor control of upper and lower limb; sitting and standing, balance control, and dexterity; mobility; activities of daily living; health-related quality of life; and cost-effectiveness. Due to methodological heterogeneity within the selected studies, statistical pooling was not considered. Two independent researchers rated all retrieved literature according to the Physiotherapy Evidence Database (PEDro) scale from which a best evidence synthesis was derived to determine the strength of the evidence for both effectiveness of the Bobath Concept and for its superiority over other approaches.

Results—

The search strategy initially identified 2263 studies. After selection based on predetermined criteria, finally, 16 studies involving 813 patients with stroke were included for further analysis. There was no evidence of superiority of Bobath on sensorimotor control of upper and lower limb, dexterity, mobility, activities of daily living, health-related quality of life, and cost-effectiveness. Only limited evidence was found for balance control in favor of Bobath. Because of the limited evidence available, no best evidence synthesis was applied for the health-related quality-of-life domain and cost-effectiveness.

Conclusions—

This systematic review confirms that overall the Bobath Concept is not superior to other approaches. Based on best evidence synthesis, no evidence is available for the superiority of any approach. This review has highlighted many methodological shortcomings in the studies reviewed; further high-quality trials need to be published. Evidence-based guidelines rather than therapist preference should serve as a framework from which therapists should derive the most effective treatment.
A New Trichotomous Measure of World-system Position Using the International Trade Network
Authors: Clark Rob , Beckfield Jason
Published: January 2009

Snyder and Kick's (1979) measure of world-system position continues to serve as the premier trichotomous network indicator of a state's location in the capitalist world economy. In this study, we identify several problems with this orthodox measure concerning its age, informal construction, and incorporation of inappropriate networks. We introduce a trichotomous network measure of world-system position that addresses these concerns, applying Borgatti and Everett's (1999) core/periphery model to a three-tiered partition using international trade data. Our trichotomous measure of the trade network identifies an expanded core, consisting of an old orthodox core joined by a set of upwardly mobile states. We estimate the effect of world-system position on economic growth and find that our trade measure significantly outperforms Snyder and Kick's orthodox measure. When controlling for human capital, the strong effects of our trade measure persist, while the weaker effects estimated by the orthodox measure largely disappear. Moreover, our models with human capital reveal that states economically converge within world-system zones, while continuing to diverge between zones.
Decoupling Values from Action
Authors: Swiss Liam
Published: January 2009

World polity explanations of the isomorphism of institutions and values among nation-states have not focused sufficient attention on explaining the decoupling or gap between granting rights and actually implementing them. This article examines the decoupling phenomenon by exploring what factors influenced the gap between granting women the right to stand for election and the eventual election of the first woman to parliament in 92 countries of the developing world from 1945 to 1990. Both the influence of the world society and concepts of state-weakness are examined as determinants of this decoupling gap. This article shows that world polity influence on the nation-state extends beyond the adoption of policy scripts to bear on the actual implementation of world cultural models.
A Theoretical Model to Study the Influence of Tow-drop Areas on the Stiffness and Strength of Variable-stiffness Laminates
Authors: Blom Adriana W. , Lopes Claudio S. , Kromwijk Peter J. , Gurdal Zafer , Camanho P.P.
Published: January 2009

Variable-stiffness laminates that have fiber orientation variation across its planform can be manufactured using advanced fiber placement technology. For such laminates, successive passes of the fiber placement head often overlap resulting in thickness build-up. If a constant thickness is desired, tows will be cut at the course boundary, which can result in small triangular resin-rich areas without any fibers. In this article a theoretical, numerical investigation of the influence of these tow-drop areas on the strength and stiffness of variable-stiffness laminates is performed. The effects of tow width, laminate thickness and staggering in combination with tow-drop areas are studied by making use of finite element simulations. A method for the localization of tow-drop areas is presented, and the expressions for implementing the tow-drop areas in a finite element model are given. Subsequently, progressive failure analyses using the LaRC failure criteria are performed. Failure occurs at tow-drop locations in both the surface plies and underlying plies. Wider tows result in lower strength. No correlation seems to exist between thickness and laminate strength, while staggering has a positive influence on strength.
Tensile Testing of Cellulose Based Natural Fibers for Structural Composite Applications
Authors: Symington Mark C. , Banks W.M. , West Opukuro David , Pethrick R.A.
Published: January 2009

A series of tensile tests were conducted on a Lloyd LRX tensile testing machine for numerous natural fibers deemed potential candidates for development in composite applications. The tensile tests were conducted on the fibers jute, kenaf, flax, abaca, sisal, hemp, and coir for samples exposed to moisture conditions of (1) room temperature and humidity, (2) 65% moisture content, (3) 90% moisture content, and (4) soaked fiber. These seven fibers were then tested for the four conditions and the mechanical properties of tensile strength, tensile strain to failure, and Young's modulus were calculated for the results. These results were then compared and verified with those from the literature, with some of the fibers showing distinctly promising potential. Additionally, a study on the effect of alkalization using 3% NaOH solution was carried out on flax, kenaf, abaca, and sisal to observe impact that this common fiber pre-treatment process has on fiber mechanical properties. The result of the investigation indicated that over treatment of natural fibers using NaOH could have a negative effect on the base fiber properties. It is consequently apparent that a treatment time of less than 10 min is sufficient to remove hemicelluloses and to give the optimum effect.