bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross-Sectional Analysis of Abnormalities of Mineral Homeostasis, Vitamin D and Parathyroid Hormone in a Cohort of Pre-Dialysis Patients
Authors: Zehnder Daniel , Landray Martin J. , Wheeler David C. , Fraser William , Blackwell Lisa , Nuttall Sarah , Hughes Sue V. , Townend John , Ferro Charles , Baigent Colin , Hewison Martin
Published: September 2007

Background: Disturbances in mineral and vitamin D metabolism, which affect parathyroid hormone (PTH) synthesis, are well recognized in patients receiving dialysis. However, it is unclear at what stage of chronic kidney disease (CKD) these abnormalities develop. Methods: The associations between CKD stages 3 and 5, and alterations of calcium, phosphate, vitamin D and PTH concentrations were assessed in 249 patients (mean age 61 years, 66% male) and 79 age- and sex-matched healthy controls. Results: As compared to controls, serum phosphate concentrations were elevated among CKD patients (1.40 vs. 1.11 mmol/l; p < 0.0001). And levels of both 25-hydroxyvitamin D (42.1 vs. 60.4 nmol/l; p < 0.0001) and 1,25-dihydroxyvitamin D (58.2 vs. 119.5 pmol/l; p < 0.0001) were lower among patients with CKD, even among those with only stage 3 CKD and despite 73% of patients receiving vitamin D supplements. The ratio of 1,25-dihydroxy- to 25-hydroxyvitamin D was lower than controls, even among patients with stage 3 CKD (p = 0.0001), and this ratio diminished with advancing renal impairment. Concomitant elevations were observed in intact PTH (13.8 vs. 4.2 pmol/l; p < 0.0001) and whole PTH (7.9 vs. 2.7 pmol/l; p < 0.0001). Conclusion: Impaired conversion of 25-hydroxy- to 1,25-dihydroxyvitamin D is an early feature of renal disease, and progresses as renal function deteriorates.
Epidemiology, Major Outcomes, Risk Factors, Prevention and Management of Chronic Kidney Disease in China
Authors: Xie Yuansheng , Chen Xiangmei
Published: September 2007

Chronic kidney disease (CKD) is common in China. In residents older than 40 years in Beijing, China, 11.3% of subjects had at least one indicator of kidney damage. The primary cause of chronic renal failure in China was glomerulonephritis, which was followed by diabetic nephropathy and hypertensive nephrosclerosis. Renal failure, cardiovascular disease and infection were important complications. IgA nephropathy (IgAN) is the most common CKD in China. The prevalence of hypertension, intrarenal artery lesions and tubulointerstitial lesions in patients with IgAN at the time of renal biopsy was approximately 40, 55 and 85%, respectively. The genetic variation in Megsin confers susceptibility to IgAN in Chinese. The patients with SL/LL genotypes of the MUC20 gene, the 38AA genotype of uteroglobin and DD genotype of the angiotensin-converting enzyme gene had a higher risk of progression. Chinese prospective clinical trials showed that benazepril (BZ) conferred substantial renal benefits in patients with advanced renal insufficiency. The combined therapy with urokinase and BZ was more effective than with BZ alone in reducing proteinuria and protecting renal function in Chinese patients with severe IgAN. Lupus nephritis (LN) is a common form of secondary renal disease diagnosed by renal biopsy in China. Chinese multicenter clinical trials showed that mycophenolate mofetil or leflunomide combined with steroids was effective as induction therapy for proliferative LN.
Effects of Resibufogenin in Experimental Hypertension
Authors: Danchuk S. , Sukhanov S. , Horvat D. , Uddin M.N. , Puschett J.B.
Published: September 2007

Background/Aims: There are two major pathophysiologic processes involved in the development of hypertension: (1) expanded extracellular fluid volume and (2) vasoconstriction. We have developed a model of preeclampsia in the rat, in which excessive volume expansion (VE) plays a role. These animals excrete increased amounts of the bufodienolide, marinobufagenin (MBG), even before their hypertension and proteinuria become established. Furthermore, their hypertension is corrected by administration of resibufogenin (RBG), a compound structurally similar to MBG. Method: We studied two models of experimental hypertension in the nonpregnant animal, produced either by deoxycorticosterone acetate (DOCA)-salt administration or by angiotensin infusion. Results: RBG administered to the DOCA-salt rats lowered blood pressure and reduced proteinuria in the VE animals, but had no affect on the rats infused with angiotensin. Furthermore, although the production of superoxide anion in the aortas of both groups of hypertensive rats was increased over control, RBG reduced these levels to normal in the VE (DOCA-salt) animals only. RBG had no effect in the angiotensin-infused rats. The urinary excretion of angiotensinogen did not rise in VE-mediated hypertension, but did increase in the angiotensin-infused rats. Conclusions: MBG plays an important role in the causation of hypertension in the VE rats, but not in the vasoconstrictive model. RBG is effective only in VE-mediated hypertension.
Angiotensin-(1–7) Prevents Activation of NADPH Oxidase and Renal Vascular Dysfunction in Diabetic Hypertensive Rats
Authors: Benter Ibrahim F. , Yousif Mariam H.M. , Dhaunsi Gursev S. , Kaur Jaspal , Chappell Mark C. , Diz Debra I.
Published: September 2007

Background/Aim: We examined the influence of chronic treatment with angiotensin-(1–7) [Ang-(1–7)] on renox (renal NADPH oxidase, NOX-4) and the development of renal dysfunction in streptozotocin-treated spontaneously hypertensive rats (diabetic SHR). Methods:Mean arterial pressure, urinary protein and vascular responsiveness of the isolated renal artery to vasoactive agonists were studied in vehicle- or Ang-(1–7)-treated SHR and diabetic SHR. Results: Ang-(1–7) decreased the elevated levels of renal NADPH oxidase (NOX) activity and attenuated the activation of NOX-4 gene expression in the diabetic SHR kidney. Ang-(1–7) treatment increased sodium excretion but did not affect mean arterial pressure in diabetic SHR. There was a significant increase in urinary protein (266 ± 22 mg/24 h) in the diabetic compared to control SHR (112 ± 13 mg/24 h) and treatment of diabetic SHR with Ang-(1–7) reduced the degree of proteinuria (185 ± 23 mg/24 h, p < 0.05). Ang-(1–7) treatment also attenuated the diabetes-induced increase in renal vascular responsiveness to endothelin-1, norepinephrine, and angiotensin II in SHR, but significantly increased the vasodilation of the renal artery of SHR and diabetic SHR to the vasodilator agonists. Conclusion: These results suggest that treatment with Ang-(1–7) constitutes a potential therapeutic strategy to alleviate NOX-mediated oxidative stress and to reduce renal dysfunction in diabetic hypertensive rats.
Suppression of Renal Tubulointerstitial Fibrosis by Small Interfering RNA Targeting Heat Shock Protein 47
Authors: Xia Zhiyin , Abe Katsushige , Furusu Akira , Miyazaki Masanobu , Obata Yoko , Tabata Yasuhiko , Koji Takehiko , Kohno Shigeru
Published: September 2007

Background/Aim: Unilateral ureteral obstruction (UUO) is a well-established model for tubulointerstitial fibrosis. During the progression of tubulointerstitial fibrosis, upregulation of collagen synthesis and subsequent accumulation of collagen were observed in the tubulointerstitial area. Heat shock protein 47 (HSP47) is a collagen-specific molecular chaperone and plays an essential role in regulating collagen synthesis. We designed small interfering RNA (siRNA) sequences for HSP47 mRNA to examine whether HSP47 is involved in the progression of renal tubulointerstitial fibrosis in a mouse UUO model. Methods: The HSP47 siRNA was injected once via the ureter at the time of UUO preparation. We also applied a new gene delivery system for siRNA using cationized gelatin microspheres. The kidneys were harvested 7 and 14 days after UUO. The HSP47 and type I, III, and IV collagen expression levels were analyzed by immunohistochemistry and Western blotting. Results: Seven days after UUO, the expression levels of HSP47 and type I, III, and IV collagens were markedly upregulated in obstructed kidneys or green fluorescent protein siRNA treated obstructed kidneys. HSP47 siRNA injection significantly reduced the protein expression levels and significantly diminished the accompanying interstitial fibrosis. Moreover, cationized gelatin microspheres as a delivery system enhanced and lengthened the antifibrotic effect of HSP47 siRNA. Conclusions: Our results indicate that HSP47 is a candidate target for the prevention of tubulointerstitial fibrosis and that selective blockade of the HSP47 expression by using siRNA could be a potentially useful therapeutic approach for patients with renal disease.
Allonursing in Tufted Capuchin Monkeys (Cebus nigritus): Milk or Pacifier?
Authors: Baldovino M. Celia , Di Bitetti Mario S.
Published: September 2007

Allonursing, the behaviour of females nursing offspring that are not their own, is relatively frequent in capuchin monkeys. Using focal-animal sampling and ad libitum observations we describe the pattern of allonursing in a wild group of tufted capuchins,Cebus nigritus(4 cohorts, 22 infants), at Iguazú National Park, north-eastern Argentina, and test several hypotheses on the adaptive value of allonursing. During 2,351 contact hours with the group (including 4,207 focal-animal samples totalizing 329 h focused on infants) we observed 39 allonursing bouts. Infants were not allonursed more frequently by close kin than by more distant allomothers. Offspring of dominant females were allonursed more frequently than those of low-ranking females. Nursing bouts were longer than allonursing bouts. Our results suggest that allonursing in tufted capuchins has a social function and is not mainly aimed at providing milk to infants.
ERK1/2 Signaling Pathway Modulates the Airway Smooth Muscle Cell Phenotype in the Rat Model of Chronic Asthma
Authors: Xie Min , Liu Xian-Sheng , Xu Yong-Jian , Zhang Zhen-Xiang , Bai Jing , Ni Wang , Chen Shi-Xin
Published: September 2007

Background: It has been demonstrated that the phenotypic modulation of airway smooth muscle cells (ASMCs) is important to the pathogenesis of airway remodeling in chronic asthma. The extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway is one of the most important transduction pathways involved in the process of asthma; however, its role in the phenotypic transition of ASMCs remains unclear. Objectives: To examine the role of ERK1/2 in the phenotypic modulation of ASMCs in the rat model of chronic asthma. Methods: Bronchial smooth muscle strips were cultured in vitro in the presence of the ERK1/2 agonist epidermal growth factor or/and the MEK inhibitor PD98059. The phenotype of ASMCs was determined by observing these cells under an electron microscope and analyzing expression of phenotypic markers (smooth muscle α-actin for the contractile phenotype and osteopontin for the synthetic) by using Western blot and reverse-transcriptase polymerase chain reaction, respectively. Results: The phenotype of the ASMCs from the chronic asthmatic rats changed from the contractile type to the synthetic type with synthetic organelles abundantly gathered around the nucleus and altered expression of phenotypic markers. ERK1/2 was strongly expressed in the ASMCs of the chronic asthmatic rats and its activation by epidermal growth factor excessively promoted the synthetic function of ASMCs; the MEK inhibitor PD98059, however, reversed this phenotypic change in the ASMCs. Conclusions: Our results reveal a key role of the ERK1/2 signaling pathway in the phenotypic modulation of ASMCs in chronic asthmatic rats, indicating that specific inhibition of ERK1/2 in ASMCs may be therapeutically valuable in the control of airway remodeling in chronic asthma.
Heme Oxygenase-1 Deficiency Accelerates Formation of Arterial Thrombosis Through Oxidative Damage to the Endothelium, Which Is Rescued by Inhaled Carbon Monoxide
Authors: True Andrea L. , Olive Michelle , Boehm Manfred , San Hong , Westrick Randal J. , Raghavachari Nalini , Xu Xiuli , Lynn Edward G. , Sack Michael N. , Munson Peter J. , Gladwin Mark T. , Nabel Elizabeth G.
Published: September 2007

Heme oxygenase (HO)-1 (encoded by
Hmox1
) catalyzes the oxidative degradation of heme to biliverdin and carbon monoxide. HO-1 is induced during inflammation and oxidative stress to protect tissues from oxidative damage. Because intravascular thrombosis forms at sites of tissue inflammation, we hypothesized that HO-1 protects against arterial thrombosis during oxidant stress. To investigate the direct function of HO-1 on thrombosis, we used photochemical-induced vascular injury in
Hmox1
−/−
and
Hmox1
+/+
mice.
Hmox1
−/−
mice developed accelerated, occlusive arterial thrombus compared with
Hmox1
+/+
mice, and we detected several mechanisms accounting for this antithrombotic effect. First, endothelial cells in
Hmox1
−/−
arteries were more susceptible to apoptosis and denudation, leading to platelet-rich microthrombi in the subendothelium. Second, tissue factor, von Willebrand Factor, and reactive oxygen species were significantly elevated in
Hmox1
−/−
mice, consistent with endothelial cell damage and loss. Third, following transplantation of
Hmox1
−/−
donor bone marrow into
Hmox1
+/+
recipients and subsequent vascular injury, we observed rapid arterial thrombosis compared with
Hmox1
+/+
mice receiving
Hmox1
+/+
bone marrow. Fourth, inhaled carbon monoxide and biliverdin administration rescued the prothrombotic phenotype in
Hmox1
−/−
mice. Fifth, using a transcriptional analysis of arterial tissue, we found that HO-1 determined a transcriptional response to injury, with specific effects on cell cycle regulation, coagulation, thrombosis, and redox homeostasis. These data provide direct genetic evidence for a protective role of HO-1 against thrombosis and reactive oxygen species during vascular damage. Induction of HO-1 may be beneficial in the prevention of thrombosis associated with vascular oxidant stress and inflammation.
Role of Ca2+-Independent Phospholipase A2and Store-Operated Pathway in Urocortin-Induced Vasodilatation of Rat Coronary Artery
Authors: Smani Tarik , Domínguez-Rodríguez Alejandro , Hmadcha Abdelkrim , Calderón-Sánchez Eva , Horrillo-Ledesma Angélica , Ordóñez Antonio
Published: September 2007

Urocortin has been shown to produce vasodilatation in several arteries, but the precise mechanism of its action is still poorly understood. Here we demonstrate the role of store operated Ca2+entry (SOCE) regulated by Ca2+-independent phospholipase A2(iPLA2) in phenylephrine hydrochloride (PE)-induced vasoconstriction, and we present the first evidence that urocortin induces relaxation by the modulation of SOCE and iPLA2in rat coronary artery. Urocortin produces an endothelium independent relaxation, and its effect is concentration-dependent (IC50≈4.5 nmol/L). We show in coronary smooth muscle cells (SMCs) that urocortin inhibits iPLA2activation, a crucial step for SOC channel activation, and prevents Ca2+influx evoked by the emptying of the stores via a cAMP and protein kinase A (PKA)–dependent mechanism. Lysophophatidylcholine and lysophosphatidylinositol, products of iPLA2, exactly mimic the effect of the depletion of the stores in presence of urocortin. Furthermore, we report that long treatment with urocortin downregulates iPLA2mRNA and proteins expression in rat coronary smooth muscle cells. In summary, we propose a new mechanism of vasodilatation by urocortin which involves the regulation of iPLA2and SOCE via the stimulation of a cAMP/PKA-dependent signal transduction cascade in rat coronary artery.
Involvement of the CD1d–Natural Killer T Cell Pathway in Neointima Formation After Vascular Injury
Authors: Ström Åsa , Wigren Maria , Hultgårdh-Nilsson Anna , Saxena Amit , Gomez Maria F. , Cardell Susanna , Fredrikson Gunilla Nordin , Nilsson Jan
Published: September 2007

Recent studies have established that the immune system plays an important role in the development of atherosclerosis. However, its role in regulating the arterial response to mechanical injury is less well studied. Arterial injury is associated with local accumulation of antibodies, and mice lacking functional T and B cells exhibit increased neointima formation, indicating that adaptive immune responses to neoantigens in the damaged tissue modulate the vascular repair process. To study the role of lipid antigen presentation in the arterial response to injury, we analyzed neointima formation in mice deficient in the lipid antigen-presenting molecule CD1d using a carotid collar model. As compared with control mice, neointima formation was reduced by >60% (
P
<0.01) in CD1d
−/−
mice. Moreover, carotid injury of wild-type C57BL/6 mice was associated with expansion of CD1d-restricted natural killer T cells in the spleen and accumulation of natural killer T cells in the periadventitial space of injured arteries. The results suggest that presentation of lipid antigens through the CD1d–natural killer T cell pathway modulates vascular repair responses.
Fractalkine Upregulates Intercellular Adhesion Molecule-1 in Endothelial Cells Through CX3CR1 and the Jak–Stat5 Pathway
Authors: Yang Xiao Ping , Mattagajasingh Subhendra , Su Shaobo , Chen Guibin , Cai Zheqing , Fox-Talbot Karen , Irani Kaikobad , Becker Lewis C.
Published: September 2007

Fractalkine (FKN) is a membrane-bound chemokine that can be released by proteolysis to produce soluble FKN (s-FKN). FKN and its receptor, CX3CR1, are believed to be important factors in atherosclerosis and may play a role in acute inflammatory responses. Although FKN is expressed on endothelial cells (ECs), CX3CR1 is reported to reside mainly on certain leukocyte populations. RT-PCR and Western blotting demonstrated that both human coronary artery and umbilical vein ECs expressed CX3CR1 mRNA and protein. Confocal microscopy showed that CX3CR1 was located at the cell membrane and to a lesser extent in the cytoplasm. Following exposure of both types of ECs to hypoxia and reoxygenation, FKN expression increased rapidly and s-FKN was shed into the culture medium. The addition of s-FKN protein to cultured ECs resulted in a dose-dependent increase in intercellular adhesion molecule (ICAM)-1 mRNA. Perfusion of mouse hearts with s-FKN protein increased expression of ICAM-1 protein in vascular endothelium. Transfection of ECs with CX3CR1-interfering RNA to knockdown the receptor resulted in decreased ICAM-1 expression after s-FKN stimulation. In addition, when ECs were stimulated with s-FKN, greater adhesion of human neutrophils to the ECs was observed. This increase was ICAM-1 dependent and was blocked by CX3CR1 knockdown. Following exposure to s-FKN, ECs exhibited increased phosphorylation of Jak2 and Stat5 and the ICAM-1 expression induced by s-FKN was blocked by silencing of Stat5 with small interfering RNA. Vascular ECs express both FKN and its receptor CX3CR1. s-FKN is shed from ECs following hypoxia/reoxygenation and acts through CX3CR1 on ECs to increase ICAM-1 expression and promote neutrophil adhesion through activation of the Jak–Stat5 pathway.
Dysphagia Bedside Screening for Acute-Stroke Patients
Authors: Trapl Michaela , Enderle Paul , Nowotny Monika , Teuschl Yvonne , Matz Karl , Dachenhausen Alexandra , Brainin Michael
Published: September 2007

Background and Purpose—

Acute-onset dysphagia after stroke is frequently associated with an increased risk of aspiration pneumonia. Because most screening tools are complex and biased toward fluid swallowing, we developed a simple, stepwise bedside screen that allows a graded rating with separate evaluations for nonfluid and fluid nutrition starting with nonfluid textures. The Gugging Swallowing Screen (GUSS) aims at reducing the risk of aspiration during the test to a minimum; it assesses the severity of aspiration risk and recommends a special diet accordingly.

Methods—

Fifty acute-stroke patients were assessed prospectively. The validity of the GUSS was established by fiberoptic endoscopic evaluation of swallowing. For interrater reliability, 2 independent therapists evaluated 20 patients within a 2-hour period. For external validity, another group of 30 patients was tested by stroke nurses. For content validity, the liquid score of the fiberoptic endoscopic evaluation of swallowing was compared with the semisolid score.

Results—

Interrater reliability yielded excellent agreement between both raters (κ=0.835,
P
<0.001). In both groups, GUSS predicted aspiration risk well (area under the curve=0.77; 95% CI, 0.53 to 1.02 in the 20-patient sample; area under the curve=0.933; 95% CI, 0.833 to 1.033 in the 30-patient sample). The cutoff value of 14 points resulted in 100% sensitivity, 50% specificity, and a negative predictive value of 100% in the 20-patient sample and of 100%, 69%, and 100%, respectively, in the 30-patient sample. Content validity showed a significantly higher aspiration risk with liquids compared with semisolid textures (
P
=0.001), therefore confirming the subtest sequence of GUSS.

Conclusions—

The GUSS offers a quick and reliable method to identify stroke patients with dysphagia and aspiration risk. Such a graded assessment considers the pathophysiology of voluntary swallowing in a more differentiated fashion and provides less discomfort for those patients who can continue with their oral feeding routine for semisolid food while refraining from drinking fluids.
B Vitamin Plasma Levels and the Risk of Ischemic Stroke and Transient Ischemic Attack in a German Cohort
Authors: Weikert Cornelia , Dierkes Jutta , Hoffmann Kurt , Berger Klaus , Drogan Dagmar , Klipstein-Grobusch Kerstin , Spranger Joachim , Möhlig Matthias , Luley Claus , Boeing Heiner
Published: September 2007

Background and Purpose—

Data from prospective studies on the associations between B vitamin plasma levels and the risk of stroke are limited. We investigated the individual and combined effects of plasma folate, vitamin B12, and pyridoxal 5-phophate (PLP) levels on the risk of ischemic stroke and transient ischemic attack (TIA) in a large, prospective German cohort.

Methods—

Incident cases of ischemic stroke or TIA were identified among 25 770 participants (age 35 to 65 years) of the European Prospective Investigation into Cancer and Nutrition-Potsdam Study during 6.0±1.5 years of follow-up. The present analysis is based on a case-cohort study comprising 779 subjects free from cardiovascular disease and 188 incident cases of cerebral ischemia (ischemic stroke or TIA). Multivariable Cox proportional-hazard models were applied to evaluate the association between B vitamin levels and risk of cerebral ischemia.

Results—

Participants in the lowest tertile of vitamin B12 values were at increased risk of cerebral ischemia compared with subjects in the highest tertile; this was not observed, however, for either folate or PLP. In subgroup analyses, the relative risks were similar in magnitude for stroke and TIA. When various combinations of B vitamin tertile levels were analyzed, only combined low folate and vitamin B12 levels (relative risk, 2.24; 95% CI, 1.10 to 4.54) were significantly related to an increased risk of cerebrovascular ischemia.

Conclusions—

Our data suggest that low vitamin B12 plasma levels, particularly in combination with low folate levels, increase the risk of cerebral ischemia. This effect may be mediated at least partly through elevations of homocysteine levels.
Progression of Carotid Stenosis Detected by Duplex Ultrasonography Predicts Adverse Outcomes in Cardiovascular High-Risk Patients
Authors: Sabeti Schila , Schlager Oliver , Exner Markus , Mlekusch Wolfgang , Amighi Jasmin , Dick Petra , Maurer Gerald , Huber Kurt , Koppensteiner Renate , Wagner Oswald , Minar Erich , Schillinger Martin
Published: September 2007

Background and Purpose—

The progression of carotid stenosis reflects the activity of atherosclerotic disease and may indicate a risk for systemic atherothrombotic complications. We investigated whether progressive carotid stenosis determined by duplex ultrasonography predicts adverse outcomes in cardiovascular high-risk patients.

Methods—

We prospectively studied 1065 of 1268 consecutive patients initially asymptomatic with respect to carotid disease. Carotid ultrasound investigations at baseline and after a median of 7.5 months (range, 6 to 9 months) were performed to identify patients with progressive stenosis as defined by Doppler velocity criteria. Patients were then followed up clinically for a median of 3.2 years for the occurrence of major adverse cardiovascular events (composite MACEs: myocardial infarction, percutaneous coronary or peripheral interventions, coronary or vascular surgery, amputation, stroke, and all-cause mortality).

Results—

We found progressive carotid stenosis in 93 patients (9%) by ultrasound and thereafter recorded 495 MACEs in 421 patients (40%) during clinical follow-up. Patients with progressive carotid stenosis had a significantly increased risk for cardiovascular events compared with patients with nonprogressive disease: adjusted hazard ratios and confidence intervals were 2.01 for composite MACEs (95% CI, 1.48 to 2.67,
P
<0.001), 2.38 for myocardial infarction (95% CI, 1.07 to 5.35,
P
=0.044), 1.59 for any coronary event (95% CI, 1.10 to 2.28,
P
=0.011), 2.00 for stroke (95% CI, 1.02 to 4.11,
P
=0.035), 2.42 for any peripheral vascular event (95% CI, 1.61 to 3.62,
P
<0.001), and 1.75 for cardiovascular death (95% CI, 1.03 to 2.97,
P
=0.039).

Conclusion—

Progression of carotid stenosis within a 6- to 9-month interval detected by duplex ultrasound predicts midterm clinical adverse events of atherosclerosis in high-risk patients affecting the coronary, cerebrovascular, and peripheral circulations.
A Randomized, Controlled Trial to Teach Middle School Children to Recognize Stroke and Call 911
Authors: Morgenstern Lewis B. , Gonzales Nicole R. , Maddox Katherine E. , Brown Devin L. , Karim Asha P. , Espinosa Nina , Moyé Lemuel A. , Pary Jennifer K. , Grotta James C. , Lisabeth Lynda D. , Conley Kathleen M.
Published: September 2007

Background and Purpose—

Underutilization of acute stroke therapy is driven by delay to hospital arrival. We present the primary results of a pilot, randomized, controlled trial to encourage calling 911 for witnessed stroke among middle school children and their parents.

Methods—

This project occurred in Corpus Christi, an urban Texas community of 325 000. Three intervention and 3 control schools were randomly selected. The intervention contained 12 hours of classroom instruction divided among sixth, seventh, and eighth grades. Parents were educated indirectly through homework assignments. Two-sample
t
tests were used to compare pretest and posttest responses.

Results—

Domain 1 test questions involved stroke pathophysiology. Intervention students improved from 29% to 34% correct; control students changed from 28% to 25%. Domain 2 test questions involved stroke symptom knowledge. Intervention school students changed from 28% correct to 43%; control school students answered 25% correctly on the pretest and 29% on the posttest. Domain 3 test questions involved what to do for witnessed stroke. Intervention school students answered 36% of questions correctly on the pretest and 54% correctly on the posttest, whereas control students changed from 32% correct to 34%. A comparison of change in the mean proportion correct over time between intervention and control students was
P
<0.001 for each of the 3 individual domains. A poor parental response rate impaired the ability to assess parental improvement.

Conclusions—

A scientific, theory-based, educational intervention can potentially improve intent to call 911 for stroke among middle school children. A different mechanism is needed to effectively diffuse the curriculum to parents.
J4 at Sweet 16: A New Wrinkle?
Authors: Behabadi Bardia F. , Mel Bartlett W.
Published: September 2007

Compartmental models provide a major source of insight into the information processing functions of single neurons. Over the past 15 years, one of the most widely used neuronal morphologies has been the cell called "j4," a layer 5 pyramidal cell from cat visual cortex originally described in Douglas, Martin, and Whitteridge (1991). The cell has since appeared in at least 28 published compartmental modeling studies, including several in this journal. In recently examining why we could not reproduce certain in vitro data involving the attenuation of signals originating in distal basal dendrites, we discovered that pronounced fluctuations in the diameter measurements of j4 lead to a bottlenecking effect that increases distal input resistances and significantly reduces voltage transfer between distal sites and the cell body. Upon smoothing these diameter fluctuations, bringing j4 more in line with other reconstructions of layer 5 pyramidal neurons, we found that the attenuation of steady-state voltage signals traveling to the cell body Vdistal/Vsoma was reduced by 60% at some locations in some branches (corresponding to a 2.5-fold increase in the voltage response at the soma for the same distal depolarization) and by 30% on average (corresponding to a 45% increase in somatic response). Changes of this magnitude could lead to different outcomes in some types of compartmental modeling studies. A smoothed version of the j4 morphology is available online at http://lnc.usc.edu/j4-smooth/ .
Spike-Frequency Adapting Neural Ensembles: Beyond Mean Adaptation and Renewal Theories
Authors: Muller Eilif , Buesing Lars , Schemmel Johannes , Meier Karlheinz
Published: September 2007

We propose a Markov process model for spike-frequency adapting neural ensembles that synthesizes existing mean-adaptation approaches, population density methods, and inhomogeneous renewal theory, resulting in a unified and tractable framework that goes beyond renewal and mean-adaptation theories by accounting for correlations between subsequent interspike intervals. A method for efficiently generating inhomogeneous realizations of the proposed Markov process is given, numerical methods for solving the population equation are presented, and an expression for the first-order interspike interval correlation is derived. Further, we show that the full five-dimensional master equation for a conductance-based integrate-and-fire neuron with spike-frequency adaptation and a relative refractory mechanism driven by Poisson spike trains can be reduced to a two-dimensional generalization of the proposed Markov process by an adiabatic elimination of fast variables. For static and dynamic stimulation, negative serial interspike interval correlations and transient population responses, respectively, of Monte Carlo simulations of the full five-dimensional system can be accurately described by the proposed two-dimensional Markov process.
Phase Transition and Hysteresis in an Ensemble of Stochastic Spiking Neurons
Authors: Kaltenbrunner Andreas , Gómez Vicenç , López Vicente
Published: September 2007

An ensemble of stochastic nonleaky integrate-and-fire neurons with global, delayed, and excitatory coupling and a small refractory period is analyzed. Simulations with adiabatic changes of the coupling strength indicate the presence of a phase transition accompanied by a hysteresis around a critical coupling strength. Below the critical coupling production of spikes in the ensemble is governed by the stochastic dynamics, whereas for coupling greater than the critical value, the stochastic dynamics loses its influence and the units organize into several clusters with self-sustained activity. All units within one cluster spike in unison, and the clusters themselves are phase-locked. Theoretical analysis leads to upper and lower bounds for the average interspike interval of the ensemble valid for all possible coupling strengths. The bounds allow calculating the limit behavior for large ensembles and characterize the phase transition analytically. These results may be extensible to pulse-coupled oscillators.
Elman Backpropagation as Reinforcement for Simple Recurrent Networks
Authors: Grüning André
Published: September 2007

Simple recurrent networks (SRNs) in symbolic time-series prediction (e.g., language processing models) are frequently trained with gradient descent--based learning algorithms, notably with variants of backpropagation (BP). A major drawback for the cognitive plausibility of BP is that it is a supervised scheme in which a teacher has to provide a fully specified target answer. Yet agents in natural environments often receive summary feedback about the degree of success or failure only, a view adopted in reinforcement learning schemes.

In this work, we show that for SRNs in prediction tasks for which there is a probability interpretation of the network's output vector, Elman BP can be reimplemented as a reinforcement learning scheme for which the expected weight updates agree with the ones from traditional Elman BP. Network simulations on formal languages corroborate this result and show that the learning behaviors of Elman backpropagation and its reinforcement variant are very similar also in online learning tasks.
Three-Dimensional Mesoscale Dipole Frontal Collisions
Authors: Dubosq Sara , Viúdez Álvaro
Published: September 2007

Frontal collisions of mesoscale baroclinic dipoles are numerically investigated using a three-dimensional, Boussinesq, and f-plane numerical model that explicitly conserves potential vorticity on isopycnals. The initial conditions, obtained using the potential vorticity initialization approach, consist of twin baroclinic dipoles, balanced (void of waves) and static and inertially stable, moving in opposite directions. The dipoles may collide in a close-to-axial way (cyclone–anticyclone collisions) or nonaxially (cyclone–cyclone or anticyclone–anticyclone collisions). The results show that the interacting vortices may bounce back and interchange partners, may merge reaching a tripole state, or may squeeze between the outer vortices. The formation of a stable tripole from two colliding dipoles is possible but is dependent on diffusion effects. It is found that the nonaxial dipole collisions can be characterized by the interchange between the domain-averaged potential and kinetic energy. Dipole collisions in two-dimensional flow display also a variety of vortex interactions, qualitatively similar to the three-dimensional cases.
Observed Oceanic Response over the Upper Continental Slope and Outer Shelf during Hurricane Ivan*
Authors: Teague W. J. , Jarosz E. , Wang D. W. , Mitchell D. A.
Published: September 2007

Hurricane Ivan passed directly over an array of 14 acoustic Doppler current profilers deployed along the outer continental shelf and upper slope in the northeastern Gulf of Mexico. Currents in excess of 200 cm s−1 were generated during this hurricane. Shelf currents followed Ekman dynamics with overlapping surface and bottom layers during Ivan’s approach and transitioned to a dominant surface boundary layer as the wind stress peaked. Slope currents at the onset of Ivan were wind driven near the surface, but deeper in the water column they were dominated during and after the passage of Ivan by subinertial waves with a period of 2–5 days that had several characteristics of topographic Rossby waves. Currents on the slope at 50 m and greater depths commonly exceeded 50 cm s−1. Surprisingly, the strongest currents were present to the left of the storm track on the shelf while more energetic currents were to the right of the hurricane path on the slope during the forced stage. Near-inertial motion lasting for a time period of about 10 days was excited by the storm on the shelf and slope. Record wave heights were measured near the eyewall of Hurricane Ivan and were shown not to be rogue waves. The large surface waves and strong near-bottom currents caused significant bottom scour on the outer shelf at water depths as deep as 90 m.
Potential Vorticity Constraint on the Flow between Two Basins
Authors: Yang Jiayan , Price James F.
Published: September 2007

This paper examines the role of potential vorticity (PV) balance in source- and sink-driven flows between two basins. As shown in previous studies, PV advection into a basin, say a positive PV advection, requires a negative frictional torque to maintain a steady PV balance. This sense of torque may be provided by a cyclonic boundary current within the basin. The PV advection through a channel is due almost entirely to advection of planetary PV, f/H, where f is the Coriolis parameter and H is the column thickness. Therefore a localized change of depth, and thus H in the channel, directly affects the PV transport and will result in a basinwide change of the circulation pattern. For example, if the channel depth is made shallower while holding the transport fixed, the PV advection is then increased and the result may be a strong recirculation within the basin, as much as two orders of magnitude greater than the transport through the channel. When the basins are connected by two channels at different latitudes or with different sill depths, the throughflow is found to be divided between the two channels in a way that satisfies the integral constraint for flow around an island. The partition of the flow between two channels appears to be such as to minimize the net frictional torque. In still another set of experiments, the large-scale pressure difference (layer thickness) between the basins is specified and held fixed, while the throughflow is allowed to vary in response to changes in the frictional torque. The interbasin transport is strongly influenced by the length of the boundary or the magnitude of the viscosity in the sense that a greater PV frictional torque allows a greater PV transport and vice versa. This result is counterintuitive, if it is assumed that the throughflow is determined by viscous drag within the channel but is a straightforward consequence of the basin-scale PV balance. Thus, the important frictional effect in these experiments is on the basin-scale flow and not on the channel scale.
The Institutional Logic of Welfare Attitudes
Authors: Larsen Christian Albrekt
Published: September 2007

Why are people who live in liberal welfare regimes so reluctant to support welfare policy? And why are people who live in social democratic welfare regimes so keen to support welfare policy? This article seeks to give an institutional account of these cross-national differences. Previous attempts to link institutions and welfare attitudes have not been convincing. The empirical studies have had large difficulties in finding the expected effects from regime-dependent differences in self-interest, class interest, and egalitarian values. This article develops a new theoretical macro—micro link by combining the literature on deservingness criteria and the welfare regime theory. The basic ideas are that three regime characteristics, (a) the degree of universalism in welfare policy, (b) the differences in economic resources between “the bottom” and “the majority,” and (c) the degree of job opportunities, have a profound impact on the public deservingness discussion and thereby on public support for welfare policy.
Examining the Relationship Between Teacher Quality as an Organizational Property of Schools and Students' Achievement and Growth Rates
Authors: Heck Ronald H.
Published: September 2007

Purpose: No Child Left Behind (NCLB) brought attention to the need for states to upgrade the criteria used to certify teachers for entry into the profession. This study focuses on collective teacher qualifications mandated by NCLB and the role they play in explaining differences in school achievement and growth rates.

Research Methods: The study examines whether school-level differences in teacher quality are related to student learning in reading and math in a longitudinal cohort consisting of more than 14,000 students nested in a random sample of 197 elementary schools.

Findings: First, as a school-level resource, collective teacher quality was positively related to school achievement levels in reading and math. Second, the strength of the relationship was conditional on school demographic composition; for example, the positive relationship in reading was enhanced in school contexts where targeted student subgroups (e.g., low socioeconomic students, students receiving English services) were more highly clustered. Third, collective teacher quality was related to increased student growth rates in math. Fourth, within schools, higher teacher quality was associated with reduced gaps in student learning rates associated with social class and race/ethnicity.

Implications: Results are consistent with studies that have found that teacher professional qualifications matter in explaining differences in student achievement. They also suggest other promising avenues through which collective teacher quality influences school effectiveness and equity outcomes.
Comparison of Two Approaches for Handling Missing Covariates in Logistic Regression
Authors: Peng Chao-Ying Joanne , Jin Zhu
Published: September 2007

For the past 25 years, methodological advances have been made in missing data treatment. Most published work has focused on missing data in dependent variables under various conditions. The present study seeks to fill the void by comparing two approaches for handling missing data in categorical covariates in logistic regression: the expectation-maximization (EM) method of weights and multiple imputation (MI). Sample data are drawn randomly from a population with known characteristics. Missing data on covariates are simulated under two conditions: missing completely at random and missing at random with different missing rates. A logistic regression model was fit to each sample using either the EM or MI approach. The performance of these two approaches is compared on four criteria: bias, efficiency, coverage, and rejection rate. Results generally favored MI over EM. Practical issues such as implementation, inclusion of continuous covariates, and interactions between covariates are discussed.
Making Evaluation Work: One School District's Experience
Authors: Avery Linda D. , Van Tassel-Baska Joyce , O'Neill Barbara
Published: September 2007

Given the paucity of evaluation studies of gifted programs in the literature, this article shares the experiences of the Greenwich Public Schools in sponsoring an external evaluation of their K - 8 program for gifted and talented youngsters. The article explains the methodology used in the evaluation, discusses findings and recommendations, and describes how the results were translated into program improvement efforts. Also addressed are the evaluators' observations about lessons learned in the process of the evaluation; these lessons reflect on the utility of information gathered.
Intellectually Gifted Preschoolers' Perceived Competence: Relations to Maternal Attitudes, Concerns, and Support
Authors: Windecker-Nelson Elizabeth , Melson Gail F. , Moon Sidney M.
Published: September 2007

The relations of maternal attitudes, concerns, and support networks to intellectually gifted children's perceived competence, as measured by the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (Harter & Pike, 1984), were examined in a sample of 28 middle-class, Caucasian mothers and their gifted preschool children. Mothers' attitudes toward independence and strictness, their concerns, and support network variables (i.e., perceived helpfulness of the network, willingness to seek help from the network, and the amount of contact the child had with network members) were found to be significantly related to multiple dimensions of children's perceived competence. Implications for theory, research, and practice address understanding gifted children's perceived competence in relation to parental correlates.
Developmental Changes in Mathematically Precocious Young Children: Longitudinal and Gender Effects
Authors: Robinson Nancy M. , Abbott Robert D. , Berninger Virginia W. , Busse Julie , Mukhopadhyay Swapna
Published: September 2007

Young children with advanced mathematical skill ( N = 276) were followed for two years, during kindergarten through 1st grade or 1st through 2nd grade. Children were randomly assigned to an intervention condition reflecting a constructivist approach or a control condition. Mean scores for the control group on standardized math verbal, and visual-spatial measures increased or remained the same. Boys gained more than girls on the quantitative and visual-spatial measures. The treatment group made greater gains than the control group on quantitative measures only. Gender did not interact with treatment condition. Correlations among the quantitative, verbal, and visual-spatial factors remained stable for control children, but the correlation between quantitative and verbal factors increased for the intervention group.
Cooperative Learning Environments: Effects on Academic Attitudes of Gifted Students
Authors: Ramsay Shula G. , Richards Herbert C.
Published: September 2007

The attitudes of academically gifted students and the general cohort toward cooperative learning and academic school subjects were studied. Three hypotheses were tested: (a) in classes where cooperative learning is used, nonidentified children will exhibit more positive attitudes toward cooperative learning methods than their more academically able peers; (b) boys will exhibit more positive attitudes toward cooperative learning than girls; (c) Gifted children, in contrast to non-gifted peers, will exhibit more positive attitudes in settings where cooperative learning is seldom or never used than in settings where such instruction is frequently used. Data obtained from 28 classes of sixth-, seventh-, and eighth-graders in four schools generally supported hypotheses (a) and (b), but not (c). Although not a strong finding, overall attitudes toward school subjects were most positive in classes where cooperative learning was used sparingly as an instructional supplement.
Gifted Women and Marriage
Authors: Hansen Jan B. , Hall Eleanor G.
Published: September 2007

This study analyzed the perceived relationship between marriage and achievement among 167 able women, ages 45-65, who were alumnae at the University of Michigan. Women who perceived their husbands as supportive believed they had high potential for achievement, in part, because of the husband's support, the couple's commitment to joint family goals, and willingness to share domestic chores. Women who perceived their husbands as occasionally supportive, felt free to achieve occasionally. These women reported that greater levels of achievement were possible if they confronted their husband through negotiation, or if they developed talents that contributed to the family's income. Women felt they had low potential for achievement if they had an unsupportive spouse or worked sorely for financial gain.
Interview with Dr. A. Harry Passow
Authors: Kirschenbaum Robert T.
Published: September 2007

This interview with Dr. A. Harry Passow was conducted at the annual meeting of the American Educational Research Association in Chicago, Illinois in April 1991. At the time of the interview, Dr. Passow was the Jacob H. Schiff Professor Emeritus of Education at Teachers College, Columbia University. Where possible, bibliography entries have been added for the publications on which Dr. Passow comments in the interview.