bluuebunny/crossref_metadata_2025 huggingface dataset:
EGF receptor transactivation mediates ANG II-stimulated mitogenesis in intestinal epithelial cells through the PI3-kinase/Akt/mTOR/p70S6K1 signaling pathway
Authors: Chiu Terence , Santiskulvong Chintda , Rozengurt Enrique
Published: September 2004

The role of epidermal growth factor receptor (EGFR) tyrosine kinase and its downstream targets in the regulation of the transition from the G0/G1 phase into DNA synthesis in response to ANG II has not been previously investigated in intestinal epithelial IEC-18 cells. ANG II induced a rapid and striking EGFR tyrosine phosphorylation, which was prevented by selective inhibitors of EGFR tyrosine kinase activity (e.g., AG-1478) or by broad-spectrum matrix metalloproteinase (MMP) inhibitor GM-6001. Pretreatment of these cells with either AG-1478 or GM-6001 reduced ANG II-stimulated DNA synthesis by ∼50%. To elucidate the downstream targets of EGFR, we demonstrated that ANG II stimulated phosphorylation of Akt at Ser473, mTOR at Ser2448, p70S6K1 at Thr389, and S6 ribosomal protein at Ser235/236. Pretreatment with AG-1478 inhibited Akt, p70S6K1, and S6 ribosomal protein phosphorylation. Inhibition of phosphatidylinositol (PI)3-kinase with LY-294002 or mTOR/p70S6K1 with rapamycin reduced [3H]thymidine incorporation by 50%, i.e., to levels comparable to those achieved by addition of either AG-1478 or GM-6001. Utilizing Akt small-interfering RNA targeted to Akt1 and Akt2, Akt protein knockdown dramatically inhibited p70S6K1 and S6 ribosomal protein phosphorylation. In contrast, AG-1478 or Akt gene silencing exerted no detectable inhibitory effect on ANG II-induced extracellular signal-regulated kinase 1/2 phosphorylation in IEC-18 cells. Taken together, our results demonstrate that EGFR transactivation mediates ANG II-stimulated mitogenesis through the PI3-kinase/Akt/mTOR/p70S6K1 signaling pathway in IEC-18 cells.
CXCL12 activation of CXCR4 regulates mucosal host defense through stimulation of epithelial cell migration and promotion of intestinal barrier integrity
Authors: Smith Jennifer M. , Johanesen Priscilla A. , Wendt Michael K. , Binion David G. , Dwinell Michael B.
Published: September 2004

Intestinal epithelial cell migration plays a key role in gastrointestinal mucosal barrier formation, enterocyte development, differentiation, turnover, wound healing, and adenocarcinoma metastasis. Chemokines, through engagement of their corresponding receptors, are potent mediators of directed cell migration and are critical in the establishment and regulation of innate and adaptive immune responses. The aim of this study was to define the role for the chemokine CXCL12 and its sole cognate receptor CXCR4 in regulating intestinal epithelial cell migration and to determine its impact on barrier integrity. CXCL12 stimulated the dose-dependent chemotactic migration of human T84 colonic epithelial cells. Epithelial cell migration was inhibited by CXCR4 neutralizing antibody, pertussis toxin, LY-294002, and PD-98059, thereby implicating Gαi, phosphatidylinositol 3-kinase (PI3-kinase), and the ERK1/2 MAP kinase pathways in CXCR4-specific signaling. CXCL12 was also shown to increase barrier integrity, as defined by transepithelial resistance and paracellular flux across differentiating T84 monolayers. To determine whether CXCL12 regulated epithelial restitution, we used the normal nontransformed intestinal epithelial cell-6 (IEC-6) wound healing model. By using RT-PCR, immunoblot analysis, and immunofluorescence microscopy, we first showed expression of both CXCR4 and its ligand by IEC-6 cells. We then demonstrated that CXCL12 activated comparable signaling mechanisms to stimulate epithelial migration in the absence of proliferation in wounded IEC-6 monolayers. Taken together, these data indicate that CXCL12 signaling via CXCR4 directs intestinal epithelial cell migration, barrier maturation, and restitution, consistent with an important mechanistic role for these molecules in mucosal barrier integrity and innate host defense.
Contribution of a time-dependent and hyperpolarization-activated chloride conductance to currents of resting and hypotonically shocked rat hepatocytes
Authors: Lan Wen-Zhi , Abbas Houria , Lam Hung D. , Lemay Anne-Marie , Hill Ceredwyn E.
Published: September 2004

Hepatocellular Cl−flux is integral to maintaining cell volume and electroneutrality in the face of the many transport and metabolic activities that describe the multifaceted functions of these cells. Although a significant volume-regulated Cl−current (VRAC) has been well described in hepatocytes, the Cl−channels underlying the large resting anion conductance have not been identified. We used a combination of electrophysiological and molecular approaches to describe potential candidates for this conductance. Anion currents in rat hepatocytes and WIF-B and HEK293T cells were measured under patch electrode-voltage clamp. With K+-free salts of Cl−comprising the major ions externally and internally, hyperpolarizing steps between −40 and −140 mV activated a time-dependent inward current in hepatocytes. Steady-state activation was half-maximal at −63 mV and 28–38% of maximum at −30 to −45 mV, previously reported hepatocellular resting potentials. Gating was dependent on cytosolic Cl−, shifting close to 58 mV/10-fold change in Cl−concentration. Time-dependent inward Cl−currents and a ClC-2-specific RT-PCR product were also observed in WIF-B cells but not HEK293T cells. All cell types exhibited typical VRAC in response to dialysis with hypertonic solutions. DIDS (0.1 mM) inhibited the hepatocellular VRAC but not the inward time-dependent current. Antibodies against the COOH terminus of ClC-2 reacted with a protein between 90 and 100 kDa in liver plasma membranes. The results demonstrate that rat hepatocytes express a time-dependent inward Cl−channel that could provide a significant depolarizing influence in the hepatocyte.
Multihormonal regulation of hepatic sinusoidalNtcpgene expression
Authors: Simon Francis R. , Fortune John , Iwahashi Mieko , Qadri Ishtiaq , Sutherland Eileen
Published: September 2004

Bile acids are efficiently removed from sinusoidal blood by a number of transporters including the Na+-taurocholate-cotransporting polypeptide (Ntcp). Na+-dependent bile salt uptake, as well as Ntcp, are expressed twofold higher in male compared with female rat livers. Also, estrogen administration to male rats decreases Ntcp expression. The aims of this study were to determine the hormonal mechanism(s) responsible for this sexually dimorphic expression of Ntcp. We examined castrated and hypophysectomized rats of both sexes. Sex steroid hormones, growth hormone, thyroid, and glucocorticoids were administered, and livers were examined for changes in Ntcp messenger RNA (mRNA). Ntcp mRNA and protein content were selectively increased in males. Estradiol selectively decreased Ntcp expression in males, whereas ovariectomy increased Ntcp in females, confirming the importance of estrogens in regulating Ntcp. Hypophysectomy decreased Ntcp mRNA levels in males and prevented estrogen administration from decreasing Ntcp, indicating the importance of pituitary hormones. Although constant infusion of growth hormone to intact males reduced Ntcp, its replacement alone after hypophysectomy did not restore the sex differences. In contrast, thyroid hormone and corticosterone increased Ntcp mRNA in hypophysectomized rats. Sex differences in Ntcp mRNA levels were produced only when the female pattern of growth hormone was administered to animals also receiving thyroid and corticosterone. Thyroid and dexamethasone also increased Ntcp mRNA in isolated rat hepatocytes, whereas growth hormone decreased Ntcp. These findings demonstrate the essential role that pituitary hormones play in the sexually dimorphic control of Ntcp expression in adult rat liver and in the mediation of estrogen effects.
Biphasic temporal pattern in exercise capacity after myocardial infarction in the rat: relationship to left ventricular remodeling
Authors: Trueblood Nathan A. , Inscore Patrick R. , Brenner Daniel , Lugassy Daniel , Apstein Carl S. , Sawyer Douglas B. , Colucci Wilson S.
Published: September 2004

After myocardial infarction (MI), there is progressive left ventricular (LV) remodeling and impaired exercise capacity. We tested the hypothesis that LV remodeling results in structural and functional changes that determine exercise impairment post-MI. Rats underwent coronary artery ligation ( n = 12) or sham ( n = 11) surgery followed by serial exercise tests and echocardiography for 16 wk post-MI. LV pressure-volume relationships were determined using a blood-perfused Langendorff preparation. Exercise capacity was 60% of shams immediately post-MI ( P < 0.05) followed by a recovery to near normal during weeks 5– 8. Thereafter, there was a progressive decline in exercise capacity to ±40% of shams ( P < 0.01). At both 8 and 16 wk post-MI, fractional shortening (FS) was reduced and end-diastolic diameter (EDD) was increased ( P < 0.01). However, neither FS nor EDD correlated with exercise at 8 or 16 wk ( r2 < 0.12, P > 0.30). LV septal wall thickness was increased at both 8 ( P = 0.17 vs. shams) and 16 wk ( P = 0.035 vs. shams) post-MI and correlated with exercise at both times ( r2 ≥ 0.50 and P ≤ 0.02 at 8 and 16 wk). Neither end-diastolic volume nor maximum LV developed pressure at 16 wk correlated with exercise capacity. Exercise capacity follows a biphasic time course post-MI. An immediate decrease is followed by an early recovery phase that is associated with compensatory LV hypertrophy. Subsequently, there is a progressive decrease in exercise capacity that is independent of further changes in LV volume or contractile function.
Attenuation of antioxidative capacity enhances reperfusion injury in aged rat myocardium after MI/R
Authors: Liu Peitan , Xu Baohuan , Cavalieri Thomas A. , Hock Carl E.
Published: September 2004

Mortality due to ischemic cardiovascular diseases is significantly higher in elderly than in young adults. Myocardial ischemia-reperfusion (MI/R) can induce oxidative stress and an inflammatory response. We hypothesized that increased vulnerability of aged myocardium to reperfusion injury could be caused by decreased antioxidative capacity, rather than increased oxidant production, after MI/R. Aged (20-mo-old) and young (4-mo-old) male F344BN rats were subjected to 30 min of myocardial ischemia by ligation of the left main coronary artery followed by release of the ligature and 4 h of reperfusion. Four experimental groups were studied: young sham-operated rats, aged sham-operated rats, young rats subjected to MI/R, and aged rats subjected to MI/R. MI/R significantly increased infiltrated leukocyte number and myeloperoxidase (MPO) activity in perinecrotic areas of hearts of young rats compared with aged MI/R rats. These changes in infiltrated leukocyte number and MPO activity were associated with an increase in superoxide generation in perinecrotic areas from hearts of young rats compared with aged rats. Plasma levels of TNF-α and IL-1β were significantly higher in young than in aged MI/R rats. However, plasma 8-hydroxy-2′-deoxyguanosine levels and creatine kinase activity were increased in aged compared with young MI/R rats. Increased reperfusion damage in aged rats was associated with a significant decrease in plasma ratio of GSH to GSSG. Our results suggest that enhanced ischemia-reperfusion injury in aged rat hearts may be related to reduced antioxidative capacity, rather than increased reactive oxygen species production. These findings contribute to a better understanding of effects of aging on oxidative stress and inflammatory responses of the heart after MI/R.
Adaptation of uterine artery thick- and thin-filament regulatory pathways to pregnancy
Authors: Xiao DaLiao , Zhang Lubo
Published: September 2004

Little is known about the adaptation of uterine artery smooth muscle contractile mechanisms to pregnancy. The present study tested the hypothesis that pregnancy differentially regulates thick- and thin-filament regulatory pathways in uterine arteries. Isometric tension, intracellular free Ca2+concentration, and phosphorylation of 20-kDa myosin light chain (MLC20) were measured simultaneously in uterine arteries isolated from nonpregnant and near-term (140 days gestation) pregnant sheep. Phenylephrine-mediated intracellular free Ca2+concentration, MLC20phosphorylation, and contraction tension were significantly increased in uterine arteries of pregnant compared with nonpregnant animals. In contrast, phenylephrine-mediated Ca2+sensitivity of MLC20phosphorylation was decreased in the uterine arteries of pregnant sheep. Simultaneous measurement of phenylephrine-stimulated tension and MLC20phosphorylation in the same tissue indicated a decrease in MLC20phosphorylation-independent contractions in the uterine arteries of pregnant sheep. In addition, activation of PKC produced significantly lower sustained contractions in uterine arteries of pregnant compared with nonpregnant animals in the absence of changes in MLC20phosphorylation levels in either vessels. In uterine arteries of nonpregnant sheep, the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase inhibitor PD-098059 significantly increased phenylephrine-mediated, MLC20phosphorylation-independent contractions. The results suggest that in uterine arteries, pregnancy upregulates α1-adrenoceptor-mediated Ca2+mobilization and MLC20phosphorylation. In contrast, pregnancy downregulates the Ca2+sensitivity of myofilaments, which is mediated by both thick- and thin-filament pathways.
Prediction and assessment of the time-varying effective pulmonary vein area via cardiac MRI and Doppler echocardiography
Authors: Bowman Andrew W. , Kovács Sándor J.
Published: September 2004

Accurately estimating left atrial (LA) volume with Doppler echocardiography remains challenging. Using angiography for validation, Marino et al. (Marino P, Prioli AM, Destro G, LoSchiavo I, Golia G, and Zardini P. Am Heart J 127: 886–898, 1994) determined LA volume throughout the cardiac cycle by integrating the velocity-time integrals of Doppler transmitral and pulmonary venous flow, assuming constant mitral valve and pulmonary vein areas. However, this LA volume determination method has never been compared with three-dimensional LA volume data from cardiac MRI, the gold standard for cardiac chamber volume measurement. Previously, we determined that the effective mitral valve area is not constant but varies as a function of time. Therefore, we sought to determine whether the effective pulmonary vein area (EPVA) might be time varying as well and also assessed Marino's method for estimating LA volume. We imaged 10 normal subjects using cardiac MRI and concomitant transthoracic Doppler echocardiography. LA and left ventricular (LV) volumes were measured by MRI, transmitral and pulmonary vein flows were measured by Doppler echocardiography, and time dependence was synchronized via the electrocardiogram. LA volume, estimated using Marino's method, was compared with the MRI measurements. Differences were observed, and the discrepancy between the echocardiographic and MRI methods was used to predict EPVA as a function of time. EPVA was also directly measured from short-axis MRI images and was found to be time varying in concordance with predicted values. We conclude that because EPVA and LA volume time dependence are in phase, LA filling in systole and LV filling in diastole are both facilitated. Application to subjects in select pathophysiological states is in progress.
Intracerebroventricular administration of MK-801 increases food intake through mechanisms independent of gastric emptying
Authors: Covasa M. , Hung Chun-Yi , Ritter R. C. , Burns G. A.
Published: September 2004

Systemic or hindbrain administration of MK-801, a noncompetitive N-methyl-d-aspartate receptor antagonist, increases meal size. To examine whether MK-801 enhances intake by increasing gastric emptying, we administered MK-801 (2.0 μg/3.0 μl) into the fourth ventricle [intracerebroventricular (ICV)] and measured feeding and gastric emptying of 5-ml NaCl or 15% sucrose loads. In a parallel experiment, we examined food intake and gastric emptying following intraperitoneal (IP) injection of MK-801 (100 μg/kg). MK-801, either IP or ICV, increased 30-min sucrose intake compared with control (12.3 ± 0.7 vs. 9.8 ± 0.5 and 16.6 ± 2.0 vs. 10.7 ± 0.7 ml, for IP and ICV administration, respectively). Also, IP MK-801 increased 5-min gastric emptying of NaCl (4.13 ± 0.1 ml emptied) and sucrose (3.11 ± 0.1 ml emptied) compared with control (3.75 ± 0.2 and 2.28 ± 0.1 ml emptied for NaCl and sucrose loads, respectively). In contrast, ICV MK-801 did not alter NaCl emptying (3.82 ± 0.1 ml emptied) compared with control (3.82 ± 0.3 ml emptied) and actually reduced gastric emptying of sucrose (2.1 ± 0.2 and 2.94 ± 0.1 ml emptied, for MK and vehicle, respectively). These data confirm previous results that systemic as well as hindbrain injection of MK-801 increases food intake. However, because ICV MK-801 failed to increase gastric emptying, these results indicate that MK-801 increases food intake through mechanisms independent of altered gastric emptying.
Cerebral pressure-flow relations in hypertensive elderly humans: transfer gain in different frequency domains
Authors: Serrador Jorge M. , Sorond Farzaneh A. , Vyas Mitul , Gagnon Margaret , Iloputaife Ikechukwu D. , Lipsitz Lewis A.
Published: September 2004

The dynamics of the cerebral vascular response to blood pressure changes in hypertensive humans is poorly understood. Because cerebral blood flow is dependent on adequate perfusion pressure, it is important to understand the effect of hypertension on the transfer of pressure to flow in the cerebrovascular system of elderly people. Therefore, we examined the effect of spontaneous and induced blood pressure changes on beat-to-beat and within-beat cerebral blood flow in three groups of elderly people: normotensive, controlled hypertensive, and uncontrolled hypertensive subjects. Cerebral blood flow velocity (transcranial Doppler), blood pressure (Finapres), heart rate, and end-tidal CO2 were measured during the transition from a sit to stand position. Transfer function gains relating blood pressure to cerebral blood flow velocity were assessed during steady-state sitting and standing. Cerebral blood flow regulation was preserved in all three groups by using changes in cerebrovascular resistance, transfer function gains, and the autoregulatory index as indexes of cerebral autoregulation. Hypertensive subjects demonstrated better attenuation of cerebral blood flow fluctuations in response to blood pressure changes both within the beat (i.e., lower gain at the cardiac frequency) and in the low-frequency range (autoregulatory, 0.03–0.07 Hz). Despite a better pressure autoregulatory response, hypertensive subjects demonstrated reduced reactivity to CO2. Thus otherwise healthy hypertensive elderly subjects, whether controlled or uncontrolled with antihypertensive medication, retain the ability to maintain cerebral blood flow in the face of acute changes in perfusion pressure. Pressure regulation of cerebral blood flow is unrelated to cerebrovascular reactivity to CO2.
Sonic Hedgehog Induces Arteriogenesis in Diabetic Vasa Nervorum and Restores Function in Diabetic Neuropathy
Authors: Kusano Kengo F. , Allendoerfer Karen L. , Munger William , Pola Roberto , Bosch-Marce Marta , Kirchmair Rudolf , Yoon Young-sup , Curry Cynthia , Silver Marcy , Kearney Marianne , Asahara Takayuki , Losordo Douglas W.
Published: September 2004

Objective—

The embryonic morphogen sonic hedgehog (SHh) has been shown to induce neovascularization of ischemic tissue but has not been shown to play a role in regulating vascular nerve supply. Accordingly, we investigated the hypothesis that systemic injection of SHh protein could improve nerve blood flow and function in diabetic neuropathy (DN).

Methods and Results—

Twelve weeks after induction of diabetes with streptozotocin, motor and sensory nerve conduction velocities (MCV and SCV) of the sciatic nerves were significantly reduced in diabetic rats. SHh-treated diabetic rats demonstrated marked improvement of both MCV and SCV (
P
<0.05). Laser Doppler perfusion imaging showed that nerve blood flow was significantly reduced in the diabetic rats but was restored in SHh-treated diabetic rats (
P
<0.05 versus diabetic saline-treated rats) to levels similar to those achieved with vascular endothelial growth factor-2 (VEGF-2) gene therapy. In vivo perfusion of Bandeuraea simplicifolia (BS)-1 lectin showed marked reduction in the vasa nervora in diabetic sciatic nerves but restoration of nerve vasculature to nondiabetic levels in the SHh-treated and plasmid DNA encoding human VEGF-2 (phVEGF-2)–treated diabetic nerves. Interestingly, the SHh-induced vasculature was characterized by larger diameter and more smooth muscle cell-containing vessels, compared with VEGF-2 gene-treated diabetic rats.

Conclusions—

These data indicate that Shh induces arteriogenesis and restores nerve function in DN.
Hypoxia Increases LDL Oxidation and Expression of 15-Lipoxygenase-2 in Human Macrophages
Authors: Rydberg Ellen Knutsen , Krettek Alexandra , Ullström Christina , Ekström Karin , Svensson Per-Arne , Carlsson Lena M.S. , Jönsson-Rylander Ann-Cathrine , Hansson Göran I. , McPheat William , Wiklund Olov , Ohlsson Bertil G. , Hultén Lillemor Mattsson
Published: September 2004

Objective—

Macrophage-mediated oxidation of low-density lipoprotein (LDL) by enzymes, such as the lipoxygenases, is considered of major importance for the formation of oxidized LDL during atherogenesis. Macrophages have been identified in hypoxic areas in atherosclerotic plaques.

Methods and Results—

To investigate the role of hypoxia in macrophage-mediated LDL oxidation, we incubated human monocyte-derived macrophages with LDL under normoxic (21% O
2
) or hypoxic (0% O
2
) conditions. The results showed that hypoxic macrophages oxidized LDL to a significantly higher extent than normoxic cells. Interestingly, the mRNA and protein expression of 15-lipoxygenase-2 (15-LOX-2) as well as the activity of this enzyme are elevated in macrophages incubated at hypoxia. Both the unspliced 15-LOX-2 and the spliced variant 15-LOX-2sv-a are found in macrophages. In addition, 15-LOX-2 was identified in carotid plaques in some macrophage-rich areas but was only expressed at low levels in nondiseased arteries.

Conclusions—

In summary, these observations show for the first time that 15-LOX-2 is expressed in hypoxic macrophages and in atherosclerotic plaques and suggest that 15-LOX-2 may be one of the factors involved in macrophage-mediated LDL oxidation at hypoxia.
Immune Cell Toll-Like Receptor 4 Is Required for Cardiac Myocyte Impairment During Endotoxemia
Authors: Tavener Samantha A. , Long Elizabeth M. , Robbins Stephen M. , McRae Krista M. , Van Remmen Holly , Kubes Paul
Published: September 2004

The aim of this study was to investigate the importance of Toll-like receptor 4 (TLR4) signaling on cardiac myocytes versus immune cells in lipopolysaccharide (LPS)-induced cardiac dysfunction. Cardiac myocytes isolated from LPS-treated C57Bl/6 mice showed reduced shortening and calcium transients as compared with myocytes from untreated mice. In addition, LPS-treated C57Bl/6 mice showed impaired cardiac mitochondrial function, including reduced respiration and reduced time of induction of permeability transition. All of the aforementioned cardiac dysfunction was dependent on TLR4, because LPS-treated TLR4-deficient mice did not have reduced myocyte shortening or mitochondrial dysfunction. To evaluate the role of cardiac myocyte versus leukocyte TLR4, LPS was injected into chimeric mice with TLR4-positive leukocytes and TLR4-deficient myocytes. These mice showed reduced myocyte shortening in response to LPS. Myocytes from chimeric mice with TLR4-deficient leukocytes and TLR4-positive myocytes had no response to LPS. In addition, isolated myocytes from C57Bl/6 mice subsequently treated with LPS and serum for various times did not have reduced shortening, despite the presence of TLR4 mRNA and protein, as determined by reverse-transcription polymerase chain reaction and fluorescent-activated cell sorting. In fact, cardiac myocytes had equivalent amounts of TLR4 as endothelium; however, only the latter is responsive to LPS. Furthermore, signaling pathways downstream of TLR4 were not activated during direct LPS treatment of myocytes. In conclusion, TLR4 on leukocytes, and not on cardiac myocytes, is important for cardiac myocyte impairment during endotoxemia.
Targeted Disruption of
cd73
/Ecto-5′-Nucleotidase Alters Thromboregulation and Augments Vascular Inflammatory Response
Authors: Koszalka Patrycja , Özüyaman Burcin , Huo Yuqing , Zernecke Alma , Flögel Ulrich , Braun Norbert , Buchheiser Anja , Decking Ulrich K.M. , Smith Michael L. , Sévigny Jean , Gear Adrian , Weber Artur-Aron , Molojavyi Andrei , Ding Zhaoping , Weber Christian , Ley Klaus , Zimmermann Herbert , Gödecke Axel , Schrader Jürgen
Published: September 2004

To investigate the role of adenosine formed extracellularly in vascular homeostasis, mice with a targeted deletion of the
cd73
/ecto-5′-nucleotidase were generated. Southern blot, RT-PCR, and Western blot analysis confirmed the constitutive knockout. In vivo analysis of hemodynamic parameters revealed no significant differences in systolic blood pressure, ejection fraction, or cardiac output between strains. However, basal coronary flow measured in the isolated perfused heart was significantly lower (−14%;
P
<0.05) in the mutant. Immunohistochemistry revealed strong CD73 expression on the endothelium of conduit vessels in wild-type (WT) mice. Time to carotid artery occlusion after ferric chloride (FeCl
3
) was significantly reduced by 20% in

cd73
−/−

mice (
P
<0.05). Bleeding time after tail tip resection tended to be shorter in

cd73
−/−

mice (−35%). In vivo platelet cAMP levels were 0.96±0.46 in WT versus 0.68±0.27 pmol/10
6
cells in

cd73
−/−

mice (
P
<0.05). Under in vitro conditions, platelet aggregation in response to ADP (0.05 to 10 μmol/L) was undistinguishable between the two strains. In the cremaster model of ischemia–reperfusion, the increase in leukocyte attachment to endothelium was significantly higher in

cd73
−/−

compared with WT littermates (WT 98% versus

cd73
−/−

245%;
P
<0.005). The constitutive adhesion of monocytes in ex vivo–perfused carotid arteries of WT mice was negligible but significantly increased in arteries of

cd73
−/−

mice (
P
<0.05). Thus, our data provide the first evidence that adenosine, extracellularly formed by CD73, can modulate coronary vascular tone, inhibit platelet activation, and play an important role in leukocyte adhesion to the vascular endothelium in vivo.
Experimental and Clinical Regenerative Capability of Human Bone Marrow Cells After Myocardial Infarction
Authors: Fernández-Avilés Francisco , San Román José Alberto , García-Frade Javier , Fernández María Eugenia , Peñarrubia María Jesús , de la Fuente Luis , Gómez-Bueno Manuel , Cantalapiedra Alberto , Fernández Jesús , Gutierrez Oliver , Sánchez Pedro L. , Hernández Carolina , Sanz Ricardo , García-Sancho Javier , Sánchez Ana
Published: September 2004

Bone marrow mononuclear cells (BMCs) from 20 patients with extensive reperfused myocardial infarction (MI) were used to assess their myocardial regenerative capability “in vitro” and their effect on postinfarction left ventricular (LV) remodeling. Human BMCs were labeled, seeded on top of cryoinjured mice heart slices, and cultured. BMCs showed tropism for and ability to graft into the damaged mouse cardiac tissue and, after 1 week, acquired a cardiomyocyte phenotype and expressed cardiac proteins, including connexin43. In the clinical trial, autologous BMCs (78±41×10
6
per patient) were intracoronarily transplanted 13.5±5.5 days after MI. There were no adverse effects on microvascular function or myocardial injury. No major cardiac events occurred up to 11±5 months. At 6 months, magnetic resonance showed a decrease in the end-systolic volume, improvement of regional and global LV function, and increased thickness of the infarcted wall, whereas coronary restenosis was only 15%. No changes were found in a nonrandomized contemporary control group. Thus, BMCs are capable of nesting into the damaged myocardium and acquire a cardiac cell phenotype in vitro as well as safely benefiting ventricular remodeling in vivo. Large-scale randomized trials are needed now to assess the clinical efficacy of this treatment.
Reversible Connexin 43 Dephosphorylation During Hypoxia and Reoxygenation Is Linked to Cellular ATP Levels
Authors: Turner Mark S. , Haywood Guy A. , Andreka Peter , You Lijing , Martin Patricia E. , Evans W. Howard , Webster Keith A. , Bishopric Nanette H.
Published: September 2004

Altered gap junction coupling of cardiac myocytes during ischemia may contribute to development of lethal arrhythmias. The phosphoprotein connexin 43 (Cx43) is the major constituent of gap junctions. Dephosphorylation of Cx43 and uncoupling of gap junctions occur during ischemia, but the significance of Cx43 phosphorylation in this setting is unknown. Here we show that Cx43 dephosphorylation in synchronously contracting myocytes during ischemia is reversible, independent of hypoxia, and closely associated with cellular ATP levels. Cx43 became profoundly dephosphorylated during hypoxia only when glucose supplies were limited and was completely rephosphorylated within 30 minutes of reoxygenation. Similarly, direct reduction of ATP by various combinations of metabolic inhibitors and by ouabain was closely paralleled by loss of phosphoCx43 and recovery of phosphoCx43 accompanied restoration of ATP. Dephosphorylation of Cx43 could not be attributed to hypoxia, acid pH or secreted metabolites, or to AMP-activated protein kinase; moreover, the process was selective for Cx43 because levels of phospho-extracellular signal regulated kinase (ERK)1/2 were increased throughout. Rephosphorylation of Cx43 was not dependent on new protein synthesis, or on activation of protein kinases A or G, ERK1/2, p38 mitogen-activated protein kinase, or Jun kinase; however, broad-spectrum protein kinase C inhibitors prevented Cx43 rephosphorylation while also sensitizing myocytes to reoxygenation-mediated cell death. We conclude that Cx43 is reversibly dephosphorylated and rephosphorylated during hypoxia and reoxygenation by a novel mechanism that is sensitive to nonlethal fluctuations in cellular ATP. The role of this regulated phosphorylation in the adaptation to ischemia remains to be determined.
Clinically Translated Ischemic Stroke Genomics
Authors: Meschia James F.
Published: September 2004

Cohort studies show that having a positive family history of stroke increases the odds of having a stroke by ≈30%. The heritability of stroke appears to be heterogeneous across ischemic stroke subtypes, with cardioembolic stroke being least heritable. The relative influence of stroke risk attenuates with age, but genetics does not cease to be relevant in later adulthood. Recent family history and twin studies suggest that genetic factors remain relevant even beyond the seventh decade of life. One of the challenges of gene discovery in stroke relates to the complexities of phenotype. The complexities of phenotype can be addressed by focusing on individual ischemic stroke subtypes or by studying intermediate phenotypes like leukaraiosis, which has a heritability of ≈70%. Although most stroke genetics research has focused on the identification of risk factor genes, an independent set of genes likely influences poststroke outcomes (for example, apolipoprotein E) and response to drug therapies (example, α-adducin and diuretic therapy).
Language and African Americans
Authors: Smitherman Geneva
Published: September 2004

It was nearly a generation between Martin Luther King Junior Elementary School Children, et al., v. Ann Arbor School District Board (l979) and Oakland, California, Unified School District Board’s “Resolution on Ebonics” (l996). In that time, however, public knowledge of and attitudes toward African American Language (AAL) remained largely unchanged, as was exceedingly clear from the public outcry that greeted Oakland’s resolution. The author compares King and Oakland and finds that although it is clear that history did in fact repeat itself in many ways, there are also unmistakable signs of progress in language research, pedagogy, and policy. The author points out opportunities for linguists to infuse research on African American educational achievement with the results of Black Language research. For the sake of all children, it is time to act in ways that reflect genuine valuation of language diversity and to implement policies fostering multilingualism and dialect awareness.
Research on African American English Since 1998
Authors: Green Lisa
Published: September 2004

Research on African American English (AAE) since 1998 has covered topics ranging from origins of the variety to formal semantic computations used to explain the different readings of ambiguous sentences. Much of the work on AAE during this period, especially that related to the origins debate, is in the variation theory framework. The focus of the descriptive research has been on syntactic and semantic patterns in AAE used by speakers in the adolescent to adult age group. While research on phonological patterns and formal semantics of constructions has lagged behind other areas, some noteworthy studies in these areas have appeared since 1998. As the discussion of AAE has broadened, it has been possible to compare data and approaches in different studies and raise questions that provide more insight into the linguistic variety. It is also possible to extend descriptive analyses of different constructions to use in illustrations of the systematic nature of language in introductory linguistics courses and in linguistics and education courses.
Standard English and Academic English (Dialect) Learners in the African Diaspora
Authors: Baugh John
Published: September 2004

This article compares and contrasts the learning of (Standard?) English as a second dialect in the United States with the learning of Standard English as a second language in South Africa. It argues that the common denominator of racial segregation has had clear econolinguistic and educational consequences that have been, and might continue to be, detrimental to the welfare of historically subordinated racial populations. In order to advance the teaching of Academic English, Standard English, and Workplace English in both contexts, educators should address stereotypes associated with specific varieties, students’ goals, the potential benefits of gaining communicative competence in particular varieties, and the potential consequences of not gaining that competence.
The Effects of Physician Empathy on Patient Satisfaction and Compliance
Authors: Kim Sung Soo , Kaplowitz Stan , Johnston Mark V.
Published: September 2004

The present study attempted to develop new scales of patient-perceived, empathy-related constructs and to test a model of the relationships of physician empathy and related constructs to patient satisfaction and compliance. Five hundred fifty outpatients at a large university hospital in Korea were interviewed with the questionnaire. The data were analyzed using structural equation modeling. Patient-perceived physician empathy significantly influenced patient satisfaction and compliance via the mediating factors of information exchange, perceived expertise, inter-personal trust, and partnership. Improving physician empathic communication skills should increase patient satisfaction and compliance. Health providers who wish to improve patient satisfaction and compliance should first identify components of their empathic communication needing improvement and then try to refine their skills to better serve patients.
Economic Diversity in Medical Education
Authors: Cooter Raelynn , Erdmann James B. , Gonnella Joseph S. , Callahan Clara A. , Hojat Mohammadreza , Xu Gang
Published: September 2004

Providing access to higher education across all income groups is a national priority. This analysis assessed the performance, career choice, and educational indebtedness of medical college students whose educational pursuits were assisted by the provision of financial support. The study looked at designated outcomes (academic performance, specialty choice, accumulated debt) in relation to the independent variable, family (parental) income, of 1,464 students who graduated from Jefferson Medical College between 1992 and 2002. Students were classified into groups of high, moderate, and low income based on their parental income. During the basic science years, the high-income group performed better; however, in the clinical years, performance measures were similar. Those in the high-income group tended to pursue surgery, while those in the low-income group preferred family medicine. The mean of accumulated educational debt was significantly higher for the low-income group. The study provides support for maintaining economic diversity in medical education.
Development and Utilization of Vignettes in Assessing Medical Students’ Support of Older and Younger Patients’ Medical Decisions
Authors: Schigelone Amy Schiller , Fitzgerald James T.
Published: September 2004

Currently no appropriate vignettes exist to examine issues of age-based care among students early in their medical careers. This paper addresses that issue in two parts. First, as the development of vignettes, widely used in medical research, is rarely described, suggestions for developing reliable and valid vignettes are presented. These suggestions are derived from the development of a series of vignettes assessing the support of older and younger patients’ medical decisions among first year medical students. Second, the responses to the vignettes were analyzed quantitatively and qualitatively to assess potential age-based biases. Results indicate that students do not differ in their level of support for older and younger patients’ medical decisions. However, students are more supportive of patients who desired aggressive treatments than of those who wished to end treatment. Many students did not focus on the age of the patient, but instead on the patient’s quality of life.
Standardized Assessment of Reasoning in Contexts of Uncertainty
Authors: Charlin Bernard , van der Vleuten Cees
Published: September 2004

Current written tools of assessment are mostly measuring the capacity to solve well-defined problems by the application of rules and principles, while the essence of expertise in the professions lies in the capacity to solve illdefined problems, that is, reasoning in contexts of uncertainty. The purpose of this study is to describe an approach that allows assessing ill-defined problems and to present and discuss research findings related to this approach. The tool has been used up to now mainly in medicine, however it can be applied in all health professions. The approach is based on three principles: (a) examinees are faced with a challenging authenticsituation in which several options are relevant; (b) the response format is a Likert-type scale that reflects the way information is processed in problem-solving situations, according to the script theory; and (c) scoring is based on the aggregate scoring method to take into account the variability of reasoning processes among experts. Research findings suggest that the approach permits one to reliably discriminate examinees across their level of experience, and so in very different domains. It makes it possible to measure skills or domains that were up to now difficult to measure.
Alternative Methods for Handling Attrition
Authors: Foster E. Michael , Fang Grace Y. ,   Conduct Problems Prevention Research Group
Published: September 2004

Using data from the evaluation of the Fast Track intervention, this article illustrates three methods for handling attrition. Multiple imputation and ignorable maximum likelihood estimation produce estimates that are similar to those based on listwise-deleted data. A panel selection model that allows for selective dropout reveals that highly aggressive boys accumulate in the treatment group over time and produces a larger estimate of treatment effect. In contrast, this model produces a smaller treatment effect for girls. The article’s conclusion discusses the strengths and weaknesses of the alternative approaches and outlines ways in which researchers might improve their handling of attrition.
Institutionalization of a Community Action Program Targeting Licensed Premises in Stockholm, Sweden
Authors: Wallin Eva , Lindewald Birgitta , Andréasson Sven
Published: September 2004

The objective of this article is to evaluate the level of institutionalization of a community action program targeting licensed premises in Stockholm. Five key factors were identified for institutionalization: adoption, sustainability, key leader support, structural changes, and compliance. A scale was developed to assess the strength of each factor. The results indicate a high degree of institutionalization (score 13 on a scale from 5 to 15). The authors conclude that the program activities have been sustained at a high level. A written agreement ensures that the participating organizations take responsibility for the continuing work.
Firearm Advertising
Authors: Saylor Elizabeth A. , Vittes Katherine A. , Sorenson Susan B.
Published: September 2004

In contrast to tobacco, alcohol, and other consumer products associated with health risks, we know very little about how firearm manufacturers advertise their products. The authors examined advertisements for firearms in all 27 ad-accepting magazines listed in Bacon’s Magazine Directory “guns and shooting” category. Sixty-three manufacturers spent an estimated $1,195,680 on firearm advertising during the month studied. Annual advertising costs ranged widely; manufacturers spent an estimated $28.16 in advertising per firearm produced. Firearms generally were presented as a part of a lifestyle. Self-protection was noted infrequently in the advertisements. By contrast, attributes of the gun, typically technological characteristics, were noted in almost every advertisement.
Navigating the Internet
Authors: Machill Marcel , Neuberger Christoph , Schweiger Wolfgang , Wirth Werner
Published: September 2004

This article explores the market position, quality and typical usage of German-language search engines. The use of search engines is a common Internet activity - 91 percent of Internet users employ search engines. As search engines occupy the role of gatekeepers in the information jungle of the Internet, a monopoly like Google’s (76 percent market share) is problematic in several respects. Invalid results, access to websites with inappropriate content for the young user or users’ ignorance concerning the technical and economic functionality of search engines represent further problems. To analyse these problems, the study reported here comprised three steps: a comparison of search engine performance, a representative poll among German Internet users and a laboratory experiment. It was found that users have only the basic skills required to use search engines; this is exacerbated by search engines’ lack of transparency. Manipulations (spamming) of results and a poor separation of neutral and sponsored hits add to a deficiency in user friendliness.
Research Note: The Tabloidization of British Tabloids
Authors: Uribe Rodrigo , Gunter Barrie
Published: September 2004

This research presents a content analysis of the major British tabloids over the last decade of the 20th century. Using the conceptual lens of tabloidization and the framework of McLachlan and Golding, this study shows that the coverage of tabloids can be characterized by a dominance of ‘soft’ and home stories, by a significant presence of headlines and visuals and a personalized angle of coverage. Over time, the coverage has become more ‘tabloidized’ in its form and style, but has remained constant in its range of contents. Theoretically, the results indicate that the evolution of tabloid coverage has been heterogeneous, which supports the idea that the press can be in a process of homogenization only in the areas of form and style of coverage, but not in terms of range of content. Moreover, these changes suggest that tabloidization (as a feature directly related to tabloids) should not be considered a static concept.
Social Contexts, Defensive Pedagogies, and the (Mis)uses of Educational Technology
Authors: Garrison Mark J. , Bromley Hank
Published: September 2004

This article contributes to the growing body of research exploring the importance of the social context in shaping the use of educational technologies. It presents the results of a 3 1/2 year instrumental case study examining the power of the social context to shape, in negative ways, the use of technology in one urban elementary school. Three unsuccessful dynamics are identified that serve to block effective instructional uses of computers and these behaviors are related to what Linda McNeil described as “defensive teaching.” These unsuccessful interactions, it is argued, represent actors’ efforts to resolve the dilemma of how to get through the day without confronting the overwhelming instructional tasks teachers and students at the school face. The authors conclude by noting that the use of technology did not strongly shape the interpersonal and political dynamics involved and that similar types of defensive teaching and learning can be found in educational situations without technology.
Self-Governance and Community
Authors: Benewick Robert , Tong Irene , Howell Jude
Published: September 2004

This article has three objectives: 1) to assess the contribution of villager self-government to the development of community councils in urban China; 2) to discuss whether there are lessons to be learned from the experiments in urban community councils relevant to the building of rural communities; and 3) most importantly, to raise theoretical issues common to both villager self-government and urban community councils. In fulfilling these three aims, this article will further understanding of the expansion of grassroots democracy and increasing citizens’ participation in China.

The article’s comparative approach will incorporate an analysis of the institutionalization of the ‘Four Democracies’ at the village level and the extent to which they are also being implemented in the different and varying circumstances of the urban experiments and environments. We are interested in whether the villagers’ committees and residents’ committees, especially the latter in their restyled community status, are training grounds for citizenship. The different human landscapes of village and community, however, will have a profound effect on the nature and exercise of citizenship.
The Prelude to Government Reform in China?
Authors: Li Linda Chelan
Published: September 2004

This article discusses two aspects of government reform in Shunde County in Guangdong during the 1990s, ahead of national developments. One was the restructuring of the government, including: marketization; delinking of enterprises and government bureaus; rationalization of organizational boundaries; and streamlining of the top city leadership structures. The other involved the divestment of public assets and a substantial redefinition of the role of the government in the economy. The role of local agency is highlighted in the processes of change, and the national impact of Shunde’s early reforms is noted.
Chinese Catholic Sisters in the Modernization Era
Authors: Leung Beatrice
Published: September 2004

This article aims to explore the contributions of Chinese Catholic sisters in the Deng-Jiang era by examining their way of life and the problems they face within and outside the church structure. In the course of this discussion, we look at the history of Chinese Catholic sisters and the harassment they experienced in Maoist China. In discussing the sisters’ way of life, we discover that they face important problems: difficulties with recruitment stemming from the sociopolitical situation in China, and inadequate training, both religiously and professionally, which hamper the sisters’ development. We therefore conclude that leadership and institutional norm-building within the sister congregations are matters calling for immediate attention.