bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitochondrial localization of catalase provides optimal protection from H2O2-induced cell death in lung epithelial cells
Authors: Arita Yuko , Harkness S. Hella , Kazzaz Jeffrey A. , Koo Hshi-chi , Joseph Ansamma , Melendez J.Andres , Davis Jonathan M. , Chander A. , Li Yuchi
Published: December 2005

Reactive oxygen species (ROS) can cause cell injury and death via mitochondrial-dependent pathways, and supplementation with antioxidants has been shown to ameliorate these processes. The c-Jun NH2-terminal kinase (JNK) pathway has been shown to play a critical role in ROS-induced cell death. To determine if targeting catalase (CAT) to the mitochondria provides better protection than cytosolic expression against H2O2-induced injury, the following two approaches were taken: 1) adenoviral-mediated transduction was performed using cytosolic (CCAT) or mitochondrial (MCAT) CAT cDNAs and 2) stable cell lines were generated overexpressing CAT in mitochondria ( n = 3). Cells were exposed to 250 μM H2O2, and cell survival, mitochondrial function, cytochrome c release, and JNK activity were analyzed. Although all viral transduced cells had a transient twofold increase in CAT activity, MCAT cells had significantly higher survival rates, the best mitochondrial function, and lowest JNK activity compared with CCAT and LacZ controls. The improved protection with MCAT was observed in primary type II lung epithelial cells and in transformed lung epithelial cells. In the three stable cell lines, cell survival directly correlated with extent of mitochondrial localization ( r = 0.60572, P < 0.05) and not overall CAT activity ( r = −0.45501, P < 0.05). Data indicate that targeting of antioxidants directly to the mitochondria is more effective in protecting lung epithelial cells against ROS-induced injury. This has important implications in antioxidant supplementation trials to prevent ROS-induced lung injury in critically ill patients.
Various adhesion molecules impair microvascular leukocyte kinetics in ventilator-induced lung injury
Authors: Miyao Naoki , Suzuki Yukio , Takeshita Kei , Kudo Hiroyasu , Ishii Makoto , Hiraoka Rika , Nishio Kazumi , Tamatani Takuya , Sakamoto Shinji , Suematsu Makoto , Tsumura Harukuni , Ishizaka Akitoshi , Yamaguchi Kazuhiro
Published: December 2005

Although the endothelial expression of various adhesion molecules substantially differs between pulmonary microvessels, their importance for neutrophil and lymphocyte sequestration in ventilator-induced lung injury (VILI) has not been systematically analyzed. We investigated the kinetics of polymorphonuclear cells (PMN) and mononuclear cells (MN) in the acinar microcirculation of the isolated rat lung with VILI by real-time confocal laser fluorescence microscopy, with or without inhibition of ICAM-1, VCAM-1, or P-selectin by monoclonal antibodies (MAb). Adhesion molecules in each microvessel were estimated by intravital fluorescence microscopy or immunohistochemical staining. In high tidal volume-ventilated lungs, 1) ICAM-1, VCAM-1, and P-selectin were differently upregulated in venules, arterioles, and capillaries; 2) venular PMN rolling was improved by inhibition of ICAM-1, VCAM-1, or P-selectin, whereas arteriolar PMN rolling was improved by ICAM-1 or VCAM-1 inhibition; 3) capillary PMN entrapment was ameliorated only by anti-ICAM-1 MAb; and 4) MN rolling in venules and arterioles and MN entrapment in capillaries were improved by ICAM-1 and VCAM-1 inhibition. In conclusion, the contribution of endothelial adhesion molecules to abnormal leukocyte behavior in VILI-injured microcirculation is microvessel and leukocyte specific. ICAM-1- and VCAM-1-dependent, but P-selectin-independent, arteriolar PMN rolling, which is expected to reflect the initial stage of tissue injury, should be taken as a phenomenon unique to ventilator-associated lung injury.
Central nitric oxide modulates hindquarter vasodilation elicited by AMPA receptor stimulation in the NTS of conscious rats
Authors: Dias Ana Carolina Rodrigues , Colombari Eduardo
Published: December 2005

Microinjection of S-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) in the nucleus of the solitary tract (NTS) of conscious rats causes hypertension, bradycardia, and vasoconstriction in the renal, mesenteric, and hindquarter vascular beds. In the hindquarter, the initial vasoconstriction is followed by vasodilation with AMPA doses >5 pmol/100 nl. To test the hypothesis that this vasodilation is caused by activation of a nitroxidergic pathway in the NTS, we examined the effect of pretreatment with the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME, 10 nmol/100 nl, microinjected into the NTS) on changes in mean arterial pressure, heart rate, and regional vascular conductance (VC) induced by microinjection of AMPA (10 pmol/100 nl in the NTS) in conscious rats. AMPA increased hindquarter VC by 18 ± 4%, but after pretreatment with l-NAME, AMPA reduced hindquarter VC by 16 ± 7% and 17 ± 9% (5 and 15 min after pretreatment, P < 0.05 compared with before pretreatment). Pretreatment with l-NAME reduced AMPA-induced bradycardia from 122 ± 40 to 92 ± 32 beats/min but did not alter the hypertension induced by AMPA (35 ± 5 mmHg before pretreatment, 43 ± 6 mmHg after pretreatment). Control injections with d-NAME did not affect resting values or the response to AMPA. The present study shows that stimulation of AMPA receptors in the NTS activates both vasodilatatory and vasoconstrictor mechanisms and that the vasodilatatory mechanism depends on production of nitric oxide in the NTS.
Cloning of rainbow trout SLC26A1: involvement in renal sulfate secretion
Authors: Katoh Fumi , Tresguerres Martin , Lee Kyung Mi , Kaneko Toyoji , Aida Katsumi , Goss Greg G.
Published: December 2005

The kidney plays an important role in ion regulation in both freshwater and seawater fish. However, ion transport mechanisms in the teleost kidney are poorly understood, especially at the molecular level. We have cloned a kidney-specific SLC26 sulfate/anion exchanger from rainbow trout ( Oncorhynchus mykiss) that is homologous to the mammalian SLC26A1 (Sat-1). Excretion of excess plasma sulfate concentration after Na2SO4injection corresponded to significantly higher expression of the cloned SLC26A1 mRNA. Detailed morphological observation of rainbow trout renal tubules was also performed by light microscopy and transmission electron microscopy. According to the structure of brush border and tubular system in the cytoplasm, renal tubules of rainbow trout were classified into proximal tubule first and second (PI and PII) segments and distal tubules. In situ hybridization revealed that SLC26A1 anion exchanger mRNA is specifically localized in the PI segment of kidneys from both seawater- and freshwater-adapted rainbow trout. With immunocytochemistry, Na+-K+-ATPase and vacuolar-type H+-ATPase were colocalized to the same cells and distributed in the basolateral and the apical membranes, respectively, of the cells where the SLC26A1 mRNA expressed. These findings suggest that the cloned kidney-specific SLC26A1 is located in kidney proximal tubules and is involved in excretion of excess plasma sulfate in rainbow trout.
Vitamin E isoform-specific inhibition of the exercise-induced heat shock protein 72 expression in humans
Authors: Fischer Christian P. , Hiscock Natalie J. , Basu Samar , Vessby Bengt , Kallner Anders , Sjöberg Lars-Börje , Febbraio Mark A. , Pedersen Bente K.
Published: December 2005

Increased levels of reactive oxygen and nitrogen species, as seen in response to exercise, challenge the cellular integrity. Important protective adaptive changes include induction of heat shock proteins (HSPs). We hypothesized that supplementation with antioxidant vitamins C (ascorbic acid) and E (tocopherol) would attenuate the exercise-induced increase of HSP72 in the skeletal muscle and in the circulation. Using randomization, we allocated 21 young men into three groups receiving one of the following oral supplementations: RRR-α-tocopherol 400 IU/day + ascorbic acid (AA) 500 mg/day (CEα), RRR-α-tocopherol 290 IU/day + RRR-γ-tocopherol 130 IU/day + AA 500 mg/day (CEαγ), or placebo (Control). After 28 days of supplementation, the subjects performed 3 h of knee extensor exercise at 50% of the maximal power output. HSP72 mRNA and protein content was determined in muscle biopsies obtained from vastus lateralis at rest (0 h), postexercise (3 h), and after a 3-h recovery (6 h). In addition, blood was sampled for measurements of HSP72, α-tocopherol, γ-tocopherol, AA, and 8-iso-prostaglandin-F2α(8-PGF2α). Postsupplementation, the groups differed with respect to plasma vitamin levels. The marker of lipid peroxidation, 8-iso-PGF2α, increased from 0 h to 3 h in all groups, however, markedly less ( P < 0.05) in CEα. In Control, skeletal muscle HSP72 mRNA content increased 2.5-fold ( P < 0.05) and serum HSP72 protein increased 4-fold ( P < 0.05) in response to exercise, whereas a significant increase of skeletal muscle HSP72 protein content was not observed ( P = 0.07). In CEα, skeletal muscle HSP72 mRNA, HSP72 protein, and serum HSP72 were not different from Control in response to exercise. In contrast, the effect of exercise on skeletal muscle HSP72 mRNA and protein, as well as circulating HSP72, was completely blunted in CEαγ. The results indicate that γ-tocopherol comprises a potent inhibitor of the exercise-induced increase of HSP72 in skeletal muscle as well as in the circulation.
Transition from acute to chronic hypercapnia in patients with periodic breathing: predictions from a computer model
Authors: Norman Robert G. , Goldring Roberta M. , Clain Jeremy M. , Oppenheimer Beno W. , Charney Alan N. , Rapoport David M. , Berger Kenneth I.
Published: December 2005

Acute hypercapnia may develop during periodic breathing from an imbalance between abnormal ventilatory patterns during apnea and/or hypopnea and compensatory ventilatory response in the interevent periods. However, transition of this acute hypercapnia into chronic sustained hypercapnia during wakefulness remains unexplained. We hypothesized that respiratory-renal interactions would play a critical role in this transition. Because this transition cannot be readily addressed clinically, we modified a previously published model of whole-body CO2 kinetics by adding respiratory control and renal bicarbonate kinetics. We enforced a pattern of 8 h of periodic breathing (sleep) and 16 h of regular ventilation (wakefulness) repeated for 20 days. Interventions included varying the initial awake respiratory CO2 response and varying the rate of renal bicarbonate excretion within the physiological range. The results showed that acute hypercapnia during periodic breathing could transition into chronic sustained hypercapnia during wakefulness. Although acute hypercapnia could be attributed to periodic breathing alone, transition from acute to chronic hypercapnia required either slowing of renal bicarbonate kinetics, reduction of ventilatory CO2 responsiveness, or both. Thus the model showed that the interaction between the time constant for bicarbonate excretion and respiratory control results in both failure of bicarbonate concentration to fully normalize before the next period of sleep and persistence of hypercapnia through blunting of ventilatory drive. These respiratory-renal interactions create a cumulative effect over subsequent periods of sleep that eventually results in a self-perpetuating state of chronic hypercapnia.
Oxygen release from arterioles with normal flow and no-flow conditions
Authors: Cabrales Pedro , Tsai Amy G. , Johnson Paul C. , Intaglietta Marcos
Published: December 2005

The rate of oxygen release from arterioles (∼55 μm diameter) was measured in the hamster window chamber model during flow and no-flow conditions. Flow was stopped by microvascular transcutaneous occlusion using a glass pipette held by a manipulator. The reduction of the intra-arteriolar oxygen tension (Po2) was measured by the phosphorescence quenching of preinfused Pd-porphyrin, 100 μm downstream from the occlusion. Oxygen release from arterioles was found to be 53% greater during flow than no-flow conditions (2.6 vs. 1.7 × 10−5 ml O2·cm−2·s−1, P < 0.05). Acute hemodilution with dextran 70 was used to reduce vessel oxygen content, significantly increase wall shear stress (14%, P < 0.05), reduce Hct to 28.4% (SD 1.0) [vs. 48.8% (SD 1.8) at baseline], lower oxygen supply by the arterioles (10%, P < 0.05), and increase oxygen release from the arterioles (39%, P < 0.05). Hemodilution also increased microcirculation oxygen extraction (33% greater than nonhemodilution, P < 0.05) and oxygen consumption by the vessel wall, as shown by an increase in vessel wall oxygen gradient [difference in Po2 between the blood and the tissue side of the arteriolar wall, nonhemodiluted 16.2 Torr (SD 1.0) vs. hemodiluted 18.3 Torr (SD 1.4), P < 0.05]. Oxygen released by the arterioles during flow vs. nonflow was increased significantly after hemodilution (3.6 vs. 1.8 × 10−5 ml O2·cm−2·s−1, P < 0.05). The oxygen cost induced by wall shear stress, suggested by our findings, may be >15% of the total oxygen delivery to tissues by arterioles during flow in this preparation.
Dynamic culture in a rotating-wall vessel bioreactor differentially inhibits murine T-lymphocyte activation by mitogenic stimuli upon return to static conditions in a time-dependent manner
Authors: Simons D. M. , Gardner E. M. , Lelkes P. I.
Published: December 2005

Depressed immune function is a well-documented effect of spaceflight. Both in-flight studies and ground-based studies using microgravity analogs, such as rotating wall vessel (RWV) bioreactors, have demonstrated that mitogen-stimulated T lymphocytes exhibit decreased proliferation, IL-2 secretion, and activation marker expression in true microgravity and the dynamic RWV-culture environment. This study investigates the kinetics of RWV-induced T lymphocyte inhibition by monitoring the ability of Balb/c mouse splenocytes to become activated under static culture conditions after concanavalin A (Con A) stimulation in an RWV. Splenocytes were stimulated with Con A and cultured for up to 24 h in the RWV before being allowed to “recover” under static culture conditions in the continued presence of Con A. The T-lymphocyte fraction of splenocytes was assayed during the recovery period for IL-2 secretion, expansion of the T-lymphocyte population, and expression of the activation marker CD25. Our results indicate that CD25 expression was not affected by any duration of RWV exposure. In contrast, proliferation and IL-2 secretion were inhibited by >8 and 12 h of exposure, respectively. Culture in the RWV for 24 h resulted in a near-complete loss of cellular viability during the recovery period, which was not seen in cells maintained in the RWV for 16 h or less. Taken together, these results indicate that for up to 8 h of RWV culture activation is not significantly impaired upon return to static conditions; longer duration RWV culture results in a gradual loss of activation during the recovery period most likely because of decreased T-cell viability and/or IL-2 production.
Growth hormone response to graded exercise intensities is attenuated and the gender difference abolished in older adults
Authors: Weltman Arthur , Weltman Judy Y. , Roy Cathy Pritzlaff , Wideman Laurie , Patrie James , Evans William S. , Veldhuis Johannes D.
Published: December 2005

We investigated the joint impact of age, gender, and exercise intensity on growth hormone (GH) secretion. At a university center, nine young men, eight young women, seven older men, and six older women were each tested on six randomly ordered occasions [control (C) and 5 exercise conditions (Ex)]. Serum GH concentrations were measured by immunochemiluminometry [10-min samples: 0700–0900 (baseline); 0900–1300 (C or Ex + recovery)]. Integrated GH concentrations (IGHC) were calculated by trapezoidal reconstruction, and GH secretion was modeled by deconvolution analyses. Subjects exercised from 0900 to 0930 at graded intensities [standardized to individual lactate threshold (LT)] of 25 and 75% of the difference between rest and LT, LT, and 25 and 75% of the difference between LT and peak oxygen consumption. Data were analyzed via mixed-effects ANOVA for repeated measures with post hoc contrasts. We found that 1) Ex elevated IGHC above C in all four cohorts, 2) 1.75 LT Ex resulted in maximal IGHC, 3) IGHC differed by gender in young (women > men) but not older adults, 4) older adults secreted 50% less GH during graded exercise, 5) Ex selectively augmented the mass of GH secreted per burst, and 6) higher Ex + recovery IGHC in young women was due to higher baseline IGHC, rather than greater stimulated GH secretion. We conclude that young women manifest a greater absolute and incremental IGHC response to exercise than postmenopausal women and men of any age. Age diminishes the GH response to exercise and abolishes the young-adult gender difference. Attenuation of GH responses to all exercise intensities in older adults has implications for exercise prescription because higher exercise intensities may be required to stimulate GH release in older adults.
Effects of chronic cold exposure on the endothelin system
Authors: Chen Gin-Fu , Sun Zhongjie
Published: December 2005

Cold temperatures have adverse effects on the human cardiovascular system. Endothelin (ET)-1 is a potent vasoconstrictor. We hypothesized that cold exposure increases ET-1 production and upregulates ET type A (ETA) receptors. The aim of this study was to determine the effect of cold exposure on regulation of the ET system. Four groups of rats (6–7 rats/group) were used: three groups were exposed to moderate cold (6.7 ± 2°C) for 1, 3, and 5 wk, respectively, and the remaining group was maintained at room temperature (25°C) and served as control. Cold exposure significantly increased ET-1 levels in the heart, mesenteric arteries, renal cortex, and renal medulla. Cold exposure increased ETA receptor protein expression in the heart and renal cortex. ET type B (ETB) receptor expression, however, was decreased significantly in the heart and renal medulla of cold-exposed rats. Cold exposure significantly increased the ratio of ETA to ETB receptors in the heart. An additional four groups of rats (3 rats/group) were used to localize changes in ETA and ETB receptors at 1, 3, and 5 wk of cold exposure. Immunohistochemical analysis showed an increase in ETA, but a decrease in ETB, receptor immunoreactivity in cardiomyocytes of cold-exposed rats. Increased ETA receptor immunoreactivity was also found in vascular smooth muscle cells of cold-exposed rats. Cold exposure increased ETA receptor immunoreactivity in tubule epithelial cells in the renal cortex but decreased ETB receptor immunoreactivity in tubule epithelial cells in the renal medulla. Therefore, cold exposure increased ET-1 production, upregulated ETA receptors, and downregulated ETB receptors.
Shear Induces a Unique Series of Morphological Changes in Translocating Platelets
Authors: Maxwell Mhairi J. , Dopheide Sacha M. , Turner Samantha J. , Jackson Shaun P.
Published: December 2005

Objective—

The platelet glycoprotein (GP) Ib/V/IX complex plays an important role in regulating the morphology of resting platelets and can induce shape change during adhesion to immobilized von Willebrand factor (vWf). In this study we have examined the effects of fluid shear stress on GPIb-dependent changes in platelet morphology during translocation on vWf.

Methods and Results—

We demonstrate that translocating platelets undergo a unique series of morphological changes in response to increasing fluid shear stress. Under moderately low shear conditions (600 s
−1
), initial shape change involved extension of membrane tethers and/or filopodia from the platelet surface. With increasing shear rate, platelets adopted a spherical morphology with numerous surface projections (1800 to 5000 s
−1
). At high wall shear rates (10000 to 20 000 s
−1
), translocating platelets retracted filopodia, developing a smooth ball-like appearance. These changes in morphology were dependent on reorganization of the actin and microtubule components of the cytoskeleton and were regulated by intracellular signaling processes linked to Src kinases. Functionally, alterations in platelet shape had a major effect on translocation dynamics in that conversion from discs to spheres resulted in a 3- to 8-fold increase in rolling velocity.

Conclusions—

These studies demonstrate that platelets undergo shear-specific morphological changes during surface translocation on vWf that may serve to regulate translocation dynamics under flow.
TNF-α Contributes to Endothelial Dysfunction in Ischemia/Reperfusion Injury
Authors: Zhang Cuihua , Xu Xiangbin , Potter Barry J. , Wang Wei , Kuo Lih , Michael Lloyd , Bagby Gregory J. , Chilian William M.
Published: December 2005

Background—

Despite the importance of endothelial function for coronary regulation, there is little information and virtually no consensus about the causal mechanisms of endothelial dysfunction in myocardial ischemia/reperfusion (I/R) injury. Because tumor necrosis factor-α (TNF-α) is reportedly expressed during ischemia and can induce vascular inflammation leading to endothelial dysfunction, we hypothesized that this inflammatory cytokine may play a pivotal role in I/R injury-induced coronary endothelial dysfunction.

Methods and Results—

To test this hypothesis, we used a murine model of I/R (30 minutes/90 minutes) in conjunction with neutralizing antibodies to block the actions of TNF-α. TNF-α expression was increased >4-fold after I/R. To determine whether TNF-α abrogates endothelial function after I/R, we assessed endothelial-dependent (ACh) and endothelial-independent (SNP) vasodilation. In sham controls, ACh induced dose-dependent vasodilation that was blocked by the nitric oxide synthase (NOS) inhibitor L-NMMA (10 μmol/L), suggesting a key role for NO. In the I/R group, dilation to ACh was blunted, but SNP-induced dilation was preserved. Subsequent incubation of vessels with the superoxide (O
2
·−
) scavenger (TEMPOL), or with the inhibitors of xanthine oxidase (allopurinol, oxypurinol), or previous administration of anti-TNF-α restored endothelium-dependent dilation in the I/R group and reduced I/R-stimulated O
2
·−
production in arteriolar endothelial cells. Activation of xanthine oxidase with I/R was prevented by allopurinol or anti–TNF-α.

Conclusions—

These results suggest that myocardial I/R initiates expression of TNF-α, which induces activation of xanthine oxidase and production of O
2
·−
, leading to coronary endothelial dysfunction.
15d-Prostaglandin J
2
Protects Brain From Ischemia-Reperfusion Injury
Authors: Lin Teng-Nan , Cheung Wai-Mui , Wu Jui-Sheng , Chen Jean-Ju , Lin Heng , Chen Jin-Jer , Liou Jun-Yang , Shyue Song-Kun , Wu Kenneth K.
Published: December 2005

Objective—

Brain expresses abundant lipocalin-type prostaglandin (PG) D
2
(PGD
2
) synthase but the role of PGD
2
and its metabolite, 15-deoxy-Δ
12,14
PGJ
2
(15d-PGJ
2
) in brain protection is unclear. The aim of this study is to assess the effect of 15d-PGJ
2
on neuroprotection.

Methods and Results—

Adenoviral transfer of cyclooxygenase-1 (Adv-COX-1) was used to amplify the production of 15d-PGJ
2
in ischemic cortex in a rat focal infarction model. Cortical 15d-PGJ
2
in Adv-COX-1–treated rats was increased by 3-fold over control, which was correlated with reduced infarct volume and activated caspase 3, and increased peroxisome proliferator activated receptor-γ (PPARγ) and heme oxygenase-1 (HO-1). Intraventricular infusion of 15d-PGJ
2
resulted in reduction of infarct volume, which was abrogated by a PPARγ inhibitor. Rosiglitazone infusion had a similar effect. 15d-PGJ
2
and rosiglitazone at low concentrations suppressed H
2
O
2
-induced rat or human neuronal apoptosis and necrosis and induced PPARγ and HO-1 expression. The anti-apoptotic effect was abrogated by PPARγ inhibition.

Conclusion—

15d-PGJ
2
suppressed ischemic brain infarction and neuronal apoptosis and necrosis in a PPARγ dependent manner. 15d-PGJ
2
may play a role in controlling acute brain damage induced by ischemia-reperfusion.
Metformin Inhibits Proinflammatory Responses and Nuclear Factor-κB in Human Vascular Wall Cells
Authors: Isoda Kikuo , Young James L. , Zirlik Andreas , MacFarlane Lindsey A. , Tsuboi Naotake , Gerdes Norbert , Schönbeck Uwe , Libby Peter
Published: December 2005

Objective—

Metformin may benefit the macrovascular complications of diabetes independently of its conventional hypoglycemic effects. Accumulating evidence suggests that inflammatory processes participate in type 2 diabetes and its atherothrombotic manifestations. Therefore, this study examined the potential action of metformin as an inhibitor of pro-inflammatory responses in human vascular smooth muscle cells (SMCs), macrophages (Mφs), and endothelial cells (ECs).

Methods and Results—

Metformin dose-dependently inhibited IL-1β–induced release of the pro-inflammatory cytokines IL-6 and IL-8 in ECs, SMCs, and Mφs. Investigation of potential signaling pathways demonstrated that metformin diminished IL-1β–induced activation and nuclear translocation of nuclear factor-kappa B (NF-κB) in SMCs. Furthermore, metformin suppressed IL-1β–induced activation of the pro-inflammatory phosphokinases Akt, p38, and Erk, but did not affect PI3 kinase (PI3K) activity. To address the significance of the anti-inflammatory effects of a therapeutically relevant plasma concentration of metformin (20 μmol/L), we conducted experiments in ECs treated with high glucose. Pretreatment with metformin also decreased phosphorylation of Akt and protein kinase C (PKC) in ECs under these conditions.

Conclusions—

These data suggest that metformin can exert a direct vascular anti-inflammatory effect by inhibiting NF-κB through blockade of the PI3K–Akt pathway. The novel anti-inflammatory actions of metformin may explain in part the apparent clinical reduction by metformin of cardiovascular events not fully attributable to its hypoglycemic action.
Thromboxane A2/Prostaglandin H2 Receptor Activation Mediates Angiotensin II–Induced Postischemic Neovascularization
Authors: Michel Frédéric , Silvestre Jean-Sébastien , Waeckel Ludovic , Corda Stefano , Verbeuren Tony , Vilaine Jean Paul , Clergue Michel , Duriez Micheline , Levy Bernard I.
Published: December 2005

Objective—

We analyzed the involvement of thromboxane (TX) A
2
/prostaglandin (PG) H
2
(TP) receptor in ischemia-induced neovascularization in mice.

Methods and Results—

Unilateral hindlimb ischemia was induced by right femoral artery ligature in male C57BL/6J mice (n=7 per group). Animals were then treated with or without TP receptor antagonist (S18886, 5 or 10 mg/kg per day; ramatroban, 10 mg/kg per day) or aspirin (30 mg/kg per day) in drinking water for 21 days. Hindlimb ischemia raised plasma level of TXB
2,
the stable metabolite of TXA
2
, by 4.7-fold. This increase was blocked by aspirin treatment whereas S18886 (5 or 10 mg/kg per day) had no effect. However, neither S 18886 nor aspirin affected postischemic neovascularization. We next assessed the putative involvement of TXA
2
signaling in angiotensin II (Ang II) proangiogenic pathway. Ang II (0.3 mg/kg per day) enhanced TXB
2
plasma levels by 2.6-fold over that of control (
P
<0.01). Ang II-induced TXB
2
upregulation was reduced by cotreatment with Ang II type I receptor antagonist (candesartan, 20 mg/kg per day). Angiographic score, capillary number, and foot perfusion were improved by 1.7-, 1.7-, and 1.4-fold, respectively, in Ang II-treated mice compared with controls (
P
<0.05). Ang II proangiogenic effect was associated with a 1.6-fold increase in VEGF-A protein content (
P
<0.05) and a 1.4-fold increase in the number of Mac-3–positive cells (ie, macrophages) in ischemic areas (
P
<0.05). Interestingly, treatments with TP receptor antagonists or aspirin hampered the proangiogenic effects of Ang II.

Conclusion—

Endogenous activation of TXA
2
receptor by eicosanoids did not modulate spontaneous neovascularization in the setting of ischemia. Conversely, TXA
2
signaling is involved in Ang II-induced AT1-dependent vessel growth.
Atherosclerosis in Mice Is Not Affected by a Reduction in Tissue Factor Expression
Authors: Tilley Rachel E. , Pedersen Brian , Pawlinski Rafal , Sato Yuichiro , Erlich Jonathan H. , Shen Yuechun , Day Sharlene , Huang Ying , Eitzman Daniel T. , Boisvert William A. , Curtiss Linda K. , Fay William P. , Mackman Nigel
Published: December 2005

Objective—

To determine whether tissue factor (TF) contributes to the progression of atherosclerotic lesions in mice.

Methods and Results—

We determined the effect of a 50% reduction of TF levels in all cells on atherosclerosis in apolipoprotein E-deficient (apoE
−/−
) mice. No differences were observed in the extent of atherosclerosis in apoE
−/−
/TF
+/+
and apoE
−/−
/TF
+/−
mice fed regular chow for 34 weeks. Atherosclerosis could not be analyzed in apoE
−/−
mice expressing low levels of TF because of premature death of these mice. Macrophages are a major source of TF in atherosclerotic plaques. Therefore, in a second series of experiments, we investigated the effect on atherosclerosis of selectively reducing hematopoietic cell-derived TF by transplanting bone marrow from mice expressing low levels of TF into low-density lipoprotein receptor deficient (LDLR
−/−
) mice. Atherosclerosis within the arterial tree and aortic root were similar in LDLR
−/−
mice with low-TF bone marrow compared with control bone marrow (TF
+/+
or TF
+/−
) after 4 and 16 weeks on an atherogenic diet. Furthermore, the cellular composition of the aortic root lesions was similar between the 2 groups.

Conclusions—

Our data indicate that either a 50% reduction of TF in all cells or a selective reduction in hematopoietic cell-derived TF does not affect the development of atherosclerotic lesions in mice.
Mitogen-Activated Protein Kinases Control Cardiac KChIP2 Gene Expression
Authors: Jia Ying , Takimoto Koichi
Published: December 2005

Hypertrophied myocardium is associated with reductions in the transient outward K
+
current (
I
to) and expression of pore-forming Kv4.2/4.3 and auxiliary KChIP2 subunits. Here we show that KChIP2 mRNA and protein levels are dramatically decreased to 10% to 30% of control levels in the left ventricle of aorta-constricted rats in vivo and phenylephrine (PE)-treated myocytes in vitro. PE also markedly decreases
I
to density. Inhibition of protein kinase Cs (PKCs) does not affect the PE-induced reduction in KChIP2 mRNA level, whereas activation of PKC with phorbol ester (phorbol myristate [PMA]) causes a marked reduction in KChIP2 mRNA level. Pharmacological inhibition of MEKs or overexpression of a dominant-negative MEK1 increases the basal KChIP2 mRNA expression and blocks the PMA-induced decrease in auxiliary subunit mRNA level. In addition, a constitutively active MEK1 decreases the basal KChIP2 mRNA level, and PMA causes no further reduction in auxiliary subunit mRNA level in active MEK1-expressing cells. Furthermore, pharmacological inhibition of JNKs or overexpression of a dominant-negative JNK1 prevents the PE-induced, but not PMA-induced, reduction in KChIP2 mRNA expression. These results suggest that downregulation of KChIP2 expression significantly contributes to the hypertrophy-associated reduction in
I
to density. They also indicate that the expression of KChIP2 mRNA is controlled by the 2 branches of mitogen-activated protein kinase pathways: JNKs play a predominant role in mediating the PE-induced reduction, whereas the MEK-ERK pathway influences the basal expression and mediates the PKC-mediated downregulation.
Accelerated Arteriosclerosis of Vein Grafts in Inducible NO Synthase
−/−
Mice Is Related to Decreased Endothelial Progenitor Cell Repair
Authors: Mayr Ursula , Zou Yiping , Zhang Zhongyi , Dietrich Hermann , Hu Yanhua , Xu Qingbo
Published: December 2005

Inducible NO synthase (iNOS) is expressed by macrophages and smooth muscle cells in atherosclerotic lesions. Previously, we have established a mouse model for vein graft arteriosclerosis by grafting autologous jugular veins or vena cava to carotid arteries. Using this model, we studied the role of iNOS in the development of vein graft arteriosclerosis in iNOS
−/−
mice. Four weeks after grafting, neointimal hyperplasia of vein grafts in iNOS
−/−
mice was increased 2-fold compared with that of wild-type controls. Neointimal lesions contained mainly MAC-1
+
macrophages and α-actin
+
smooth muscle cells (SMCs) in both vein grafts of iNOS
−/−
and iNOS
+/+
mice. Immunofluorescence analysis revealed that increased iNOS expression in neointimal macrophages and SMCs of wild-type, but not iNOS
−/−
, mice coincided with increased vascular endothelial growth factor (VEGF) expression in vein grafts. When vein grafts were performed in iNOS
−/−
/TIE2-LacZ transgenic mice expressing LacZ gene only in endothelial cells, the number of β-galactosidase
+
cells in iNOS
−/−
vein grafts were significantly decreased. Furthermore, treatment with the NOS inhibitor
N
G
-nitro-
l
-arginine methyl ester resulted in delayed endothelial progenitor cell attachment, whereas
l
-arginine intake through drinking water enhanced endothelial repair. Interestingly, local application of VEGF to iNOS
−/−
vein grafts restored endothelial progenitor homing and reduced neointimal lesions, whereas the VEGF receptor inhibitor SU1498 increased the lesion formation. Additionally, iNOS-deficient SMCs showed a low level of VEGF production in response to interleukin 1β stimulation. Thus, iNOS deficiency accelerates neointima formation by abrogating VEGF production and endothelial progenitor cell attachment and differentiation.
Endothelial Cell Cortactin Phosphorylation by Src Contributes to Polymorphonuclear Leukocyte Transmigration In Vitro
Authors: Yang Lin , Kowalski Jennifer R. , Zhan Xi , Thomas Sheila M. , Luscinskas Francis W.
Published: December 2005

The underlying mechanisms that regulate leukocyte transendothelial migration through the vascular endothelium remain unclear. Cortactin is a substrate of Src tyrosine kinases and a regulator of cytoskeletal dynamics. Previous studies demonstrated a role for Src phosphorylation of cortactin in clustering of E-selectin and intercellular cell adhesion molecule-1 around adherent leukocytes. In the current study, we used an in vitro flow model to investigate the role of Src-induced cortactin phosphorylation in endothelium during polymorphonuclear leukocyte (PMN) transmigration through human umbilical vein endothelium (HUVEC) monolayers preactivated with tumor necrosis factor-α. Inhibition of Src in HUVEC using Src kinase inhibitors PP2 and SU6656 reduced PMN transmigration by 45±8% and 36±6%, respectively. Live cell imaging of green fluorescent protein–tagged cortactin in HUVEC revealed redistribution of cortactin in the region surrounding transmigrating PMN. Knockdown of cortactin in HUVEC by small interfering RNA also impaired transmigration to a similar degree, and this phenotype was rescued by reexpression of wild-type cortactin. Analysis of the location of initial arrest and locomotion of PMN adherent to HUVEC demonstrated that inhibition of Src tyrosine kinases or pretreatment with cortactin small interfering RNA reduced PMN transmigration at endothelial cell-to-cell junctions and not adhesion. Tyrosine phosphorylation of cortactin was important for transmigration, because expression of a mutant, in which the tyrosine phosphorylation sites were mutated to phenylalanine (cortactin3F), failed to rescue PMN transmigration. Moreover, expression of cortactin3F alone partially blocked PMN transmigration. These data suggest a model whereby tyrosine phosphorylation of cortactin by Src family kinases regulates PMN transmigration
Inhibition of Versican Synthesis by Antisense Alters Smooth Muscle Cell Phenotype and Induces Elastic Fiber Formation In Vitro and in Neointima After Vessel Injury
Authors: Huang Robert , Merrilees Mervyn J. , Braun Kathleen , Beaumont Brent , Lemire Joan , Clowes Alexander W. , Hinek Aleksander , Wight Thomas N.
Published: December 2005

The proteoglycan versican is implicated in several atherogenic events, including stimulation of vascular smooth muscle cell (VSMC) growth and migration, retention of lipoproteins, and promotion of thrombogenesis. A high content of intimal versican also correlates with a low content of elastin, suggesting an inhibitory role for versican in elastogenesis. To determine whether reduced production of versican can be used to enhance elastogenesis, we transduced Fischer rat VSMC (FRSMC) with a versican antisense sequence using the retroviral vector LXSN. Stable expression of versican antisense (LVaSN) significantly reduced versican production, induced a flattened morphology, reduced cell proliferation and migration, increased tropoelastin synthesis, increased elastin binding protein (S-Gal/EBP), and increased deposition of elastic fibers in long-term cultures. Add-back of chondroitin sulfate chains, or versican, decreased S-Gal/EBP and elastic fiber formation. LVaSN cells seeded into balloon catheter-injured rat carotid arteries formed neointimae containing low levels versican, increased amounts of S-Gal/EBP, and increased elastin deposits 7 days postinjury. At 4 weeks, neointimae formed from LVaSN cells were highly structured and contained multiple layers of elastic fibers and lamellae. These results indicate a central role for versican and its constituent chondroitin sulfate chains in controlling cell phenotype, elastogenesis, and intimal structure.
Low-Dose Aspirin for Prevention of Stroke in Low-Risk Patients With Atrial Fibrillation
Authors: Sato Hiroshi , Ishikawa Kinji , Kitabatake Akira , Ogawa Satoshi , Maruyama Yukio , Yokota Yoshiyuki , Fukuyama Takaya , Doi Yoshinori , Mochizuki Seibu , Izumi Tohru , Takekoshi Noboru , Yoshida Kiyoshi , Hiramori Katsuhiko , Origasa Hideki , Uchiyama Shinichiro , Matsumoto Masayasu , Yamaguchi Takenori , Hori Masatsugu
Published: December 2005

Background and Purpose—

Although the efficacy of anticoagulant therapy for primary prevention of stroke in patients with nonvalvular atrial fibrillation (NVAF) has been established, efficacy of antiplatelet therapy for low-risk patients is disputable in Japanese patients because of the frequent hemorrhagic complications. We examined the efficacy and safety of aspirin therapy in Japanese patients with NVAF in a prospective randomized multicenter trial.

Methods—

Patients with NVAF were randomized to an aspirin group (aspirin at 150 to 200 mg per day) or a control group without antiplatelet or anticoagulant therapy. Primary end points included cardiovascular death, symptomatic brain infarction, or transient ischemic attack.

Results—

A total of 426 patients were randomized to aspirin group and 445 to no treatment. The trial was stopped earlier because there were 27 primary end point events (3.1% per year; 95% CI, 2.1% to 4.6% per year) in the aspirin group versus 23 (2.4% per year; 95% CI, 1.5% to 3.5% per year) in the control group, suggesting a low possibility of superiority of the aspirin treatment for prevention of the primary end point. In addition, treatment with aspirin caused a marginally increased risk of major bleeding (7 patients; 1.6%) compared with the control group (2 patients; 0.4%; Fisher exact test
P
=0.101).

Conclusions—

For prevention of stroke in patients with NVAF, aspirin at 150 to 200 mg per day does not seem to be either effective or safe. Further prospective studies are needed to determine the best preventive therapy for cerebrovascular events in Japanese patients with NVAF.
Cerebral Oxygen Metabolism and Neuronal Integrity in Patients With Impaired Vasoreactivity Attributable to Occlusive Carotid Artery Disease
Authors: Kuroda Satoshi , Shiga Tohru , Houkin Kiyohiro , Ishikawa Tatsuya , Katoh Chietsugu , Tamaki Nagara , Iwasaki Yoshinobu
Published: December 2005

Background and Purpose—

It is still unclear that impaired cerebrovascular reactivity (CVR) to acetazolamide is comparable to elevated oxygen extraction fraction (OEF) on positron emission tomography (PET) in patients with occlusive carotid diseases. Therefore, in this study, the authors aimed to clarify whether OEF is elevated in all patients with reduced cerebral blood flow (CBF) and CVR (type 3) on single photon emission computed tomography (SPECT), and, if not, to specify the underlying pathophysiology of type 3 but normal OEF.

Methods—

This study included 46 patients who had decreased CBF and CVR on
N
-isopropyl-
p-
123
I-iodoamphetamine SPECT in the ipsilateral middle cerebral artery area attributable to occlusive carotid diseases. Hemodynamic and metabolism parameters were determined in all patients by
15
O-gas PET, and neuronal integrity was evaluated in 19 patients using
11
C-flumazenil (FMZ) PET.

Results—

OEF was significantly elevated in 20 (43.5%) of 46 type 3 patients. Another 26 type 3 patients had normal OEF. Regression analysis showed that OEF significantly correlated with cerebral metabolic rate for oxygen and
11
C-FMZ binding potential but not with other parameters. Subcortical infarction had no significant effect on OEF values.

Conclusions—

The results strongly suggest that type 3 patients with reduced CBF and CVR may be divided into 2 pathophysiologically different subgroups: misery perfusion attributable to hemodynamic compromise and matched hypometabolism attributable to incomplete infarction. Type 3 but normal OEF may represent a transition stage from misery perfusion to matched hypometabolism.
Family History of Stroke Does Not Predict Risk of Stroke After Transient Ischemic Attack
Authors: Floßmann Enrico , Rothwell Peter M.
Published: December 2005

Background and Purpose—

Animal models suggest a genetic contribution to cerebral susceptibility to ischemia. Family history of stroke (FHx
stroke
) is a risk factor for ischemic stroke, but there is significant confounding by heritability of hypertension and other intermediate phenotypes, and it is uncertain whether genetic factors have a direct independent influence on cerebral susceptibility to ischemia in man.

Methods—

We related detailed FHx
stroke
to baseline characteristics and subsequent risk of stroke in 2 population-based incidence studies and a consecutive hospital-referred series of patients with recent transient ischemic attack (TIA).

Results—

In none of the cohorts or the pooled data (757 patients; 5515 patient years follow-up; 200 ischemic strokes; 126 myocardial infarctions [MIs]) did FHx
stroke
predict ischemic stroke (odds ratio [OR], 0.87; 95% CI, 0.57 to 1.32). No associations were revealed by analyses stratified by age or hypertension in the proband, FHx
stroke
in parents versus siblings, number of affected relatives, or their age at stroke. FHx
stroke
was unrelated to presence of ischemic lesions on baseline computed tomography (OR, 0.96; 0.52 to 1.76) or risk of MI during follow-up. There was no bias attributable to any relationship between FHx
stroke
and risk factor control or medication.

Conclusions—

Family history of stroke does not predict risk of ischemic stroke after TIA.
Magnetic Resonance Angiography of Cerebral Arteries After Neonatal Venoarterial and Venovenous Extracorporeal Membrane Oxygenation
Authors: Hendrikse Jeroen , de Vries Linda S. , Groenendaal Floris
Published: December 2005

Background and Purpose—

In newborns with severe respiratory failure, extracorporeal membrane oxygenation (ECMO) has been proven to improve survival. With venoarterial ECMO, the right common carotid artery is ligated, whereas with venovenous ECMO, this carotid artery remains intact. The authors present the magnetic resonance angiography (MRA) evaluation of cerebral hemodynamics in a case of venoarterial and a case of venovenous ECMO.

Methods—

With 2D phase-contrast MRA flow volume (mL/min), measurements are obtained of the brain feeding arteries and draining veins. Time-of-flight and flow-directional MRA are used to demonstrate the anatomy and flow patterns at the level of the circle of Willis.

Results–

A total volume flow of 63 mL/min at the skull base and collateral flow via the anterior circle of Willis were measured in the infant after venoarterial ECMO, and a total volume flow of 86 mL/min and a fetal type configuration of the circle of Willis were observed in the infant after venovenous ECMO.

Conclusion—

MRA is a useful technique to quantify cerebral blood flow in neonates after venoarterial or venovenous ECMO and could be used to select neonates with insufficient collateral compensation after venoarterial ECMO, requiring revascularization surgery.
Carnitine Treatment Inhibits Increases in Cerebral Carnitine Esters and Glutamate Detected by Mass Spectrometry After Hypoxia-Ischemia in Newborn Rats
Authors: Wainwright Mark S. , Kohli Rohit , Whitington Peter F. , Chace Donald H.
Published: December 2005

Background and Purpose—

Cerebral ischemic insults disrupt normal respiratory activity in mitochondria. Carnitine plays an essential role in mitochondrial metabolism and in modulating excess acyl-coenzyme A (acyl-CoA) levels. The effects of cerebral ischemia on carnitine metabolism are not well understood, although the newborn may be particularly vulnerable to carnitine deficiency. We used a newborn rat model of hypoxia-ischemia (HI) to test the hypothesis that HI alters acyl-CoA:CoA homeostasis and that this effect can be prevented by treatment with carnitine.

Methods—

A total of 120 postnatal day 7 rats were subjected to 70 minutes of HI after treatment with 16 mmol/kg intraperitoneal
l
-carnitine or diluent. Carnitine, acylcarnitines, and excitatory amino acids were measured by mass spectrometry, and carnitine acetyl transferase activity, superoxide, and levels of the mitochondrial phospholipid cardiolipin (CL) were measured at 2- and 24-hour recovery.

Results—

HI and hypoxia were associated with a significant increase in the ratio of acyl-CoA:CoA, which was prevented by treatment with carnitine. Carnitine treatment also prevented increases in glutamate, glycine, superoxide, and decrease of CL.

Conclusions—

Carnitine metabolic pathways are compromised in HI and hypoxia. The protective effect of carnitine treatment on HI injury may be attributable to maintaining mitochondrial function.
Does
Apolipoprotein E Genotype
Influence the Risk of Ischemic Stroke, Intracerebral Hemorrhage, or Subarachnoid Hemorrhage?
Authors: Sudlow Cathie , Martínez González Nahara Ananí , Kim Jennifer , Clark Catriona
Published: December 2005

Background and Purpose—

Apolipoprotein E genotype
(
APOE
) is associated with cholesterol metabolism, ischemic heart disease, and cerebral amyloid angiopathy, and so may affect risk of both ischemic and hemorrhagic stroke.

Methods—

We comprehensively sought and identified studies of the association of apoE with ischemic stroke (IS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). We did meta-analyses to assess the evidence for an association between
APOE
and the various pathological types and subtypes of stroke, and assessed the effects of several methodological criteria.

Results—

We analyzed data from 31 eligible studies (26 IS, 8 ICH, and 3 SAH) in 5961 cases and 17 965 controls. ε4 allele–containing (ε4+) genotypes were significantly associated with IS (odds ratio [OR], 1.11; 95% CI, 1.01 to 1.22) and SAH (OR, 1.42; 95% CI, 1.01 to 1.99) and nonsignificantly with ICH (OR, 1.16; 95% CI, 0.93 to 1.44), whereas ε2+ genotypes were associated with ICH (OR, 1.32; 95% CI, 1.01 to 1.74). Associations appeared stronger with ε4+ genotypes for large artery compared with other IS subtypes and for Asian compared with white populations, and with ε2+ genotypes for lobar compared with deep hemorrhages. However, we found no association between ε4+ genotypes and IS when we analyzed only larger studies (>200 cases; OR, 0.99; 95% CI, 0.88 to 1.11) or studies without control selection bias (OR, 0.99; 95% CI, 0.85 to 1.17).

Conclusions—

Publication and selection biases make existing studies of
APOE
and stroke unreliable. Further, very large, methodologically rigorous studies are needed.