bluuebunny/crossref_metadata_2025_split huggingface dataset:
Smaller Isn't Always Better: School Size and School Participation Among Young People*
Authors: Lay J. Celeste 
Published: July 2007

Objective. Although political scientists studying the role of schools on political socialization have focused most of their efforts on curriculum, mainly civic education, education scholars have long recognized that schools influence outcomes through much more than curriculum and have examined school organization extensively, including school size. Much of the recent literature on school size supports smaller schools. The objective of this article is to examine the effect of school size on two political socialization outcomes: adolescent participation in school activities and volunteering. These outcomes are important because they are related to later adult participation.Method. A nationwide survey is used to conduct regression analyses as the primary method.Results. The results show limited support for smaller schools, even for those groups who are believed to benefit most significantly from small schools: racial minorities, low‐income students, and underachievers.Conclusion. I conclude with an appeal for caution among education reformers seeking to downsize schools and a recommendation to political socialization scholars to expand their analyses beyond civic education curriculum.
Circadian Variation in QT Dispersion Determined from a 12‐Lead Holter Recording: A Methodological Study of an Age‐ and Sex‐Stratified Group of Healthy Subjects
Authors: Hansen Stig , Rasmussen Verner , Larsen Klaus , Torp‐Pedersen Christian , Jensen Gorm Boje 
Published: July 2007

Background: QT dispersion is considered to reflect inhomogeneity of myocardial repolarization. Method: The circadian variation of QT interval dispersion was examined in 95 healthy subjects using 24‐hour Holter monitoring. Three different methods of lead selection were applied: all 12 leads (QTdisp 12), only precordial leads (QTdisp 6), and the pair of leads selected at 3 a.m. in which the longest and shortest QT intervals were found in each individual subject (QTdisp 2). Results: A preliminary methodological study including measurements from every minute in 10 subjects revealed no significant circadian variation using mean values of QTdisp 12, QTdisp 6, or QTdisp 2 obtained every hour, every 2, or every 4 hours, except in QTdisp 6, which demonstrated a significant circadian variation (P < 0.01) in 1‐hour measurements. Analysis of all 95 subjects using measurements obtained every 4 hours revealed a significant circadian variation in QTdisp 12 and QTdisp 6 (P < 0.0001), whereas no circadian variation was seen in QTdisp 2. A subdivision into 10‐year age groups revealed that subjects at age >50 years had a significant circadian variation in QTdisp 12 and QTdisp 6, but not in QTdisp 2. Only in males a significant circadian variation was seen in QTdisp 12 (P < 0.0001), whereas QTdisp 6 demonstrated a circadian variation both in females (P < 0.001) and in males (P < 0.0001). Conclusions: Selection of leads is of crucial importance for repetitive measurements of QT dispersion. Circadian variation was detected in subjects over 50 years of age, when all 12 or only the 6 precordial leads were taken into account.
Pacemaker Longevity: The World's Longest‐Lasting VVI Pacemaker
Authors: Katz David , Akiyama Toshio 
Published: July 2007

Objective: To describe VVI‐pacemaker longevity by model type at our institution and report on a long‐lasting model and the longest‐lasting pacemaker to be described in the literature. Background: Cardiac pacemakers are becoming increasingly common in the United States. Presently their batteries are expected to last up to 12 years. Pacemaker generator change is associated with increased cost to the health care system and is inconvenient for patients. Methods: After identifying a group of very long‐lasting CPI Microlith 605 VVI pulse generators, we reviewed records on all patients who had either Guidant or Medtronic pulse generator explantation at our institution over a 10‐year period. Average longevities were calculated for all VVI pacemakers, four common VVI models, and the CPI Microlith 605. Results: A total of 105 VVI‐programmed pacemakers were identified. Their average longevity was 7.2 years. The two most common Medtronic VVI‐programmed pacemakers explanted were the Thera (7.1 years) and Kappa (7.3 years). The two most common Guidant/CPI models were the Vigor (4.2 years) and Discovery (5.7 years). The CPI Microlith 605 (19.2 years) lasted more than 26 years in one patient before being explanted. Conclusion: At a time when pacemakers are being used more frequently, pacemaker longevity may decrease as a result of the use of dual‐chamber pacing systems. In our study, the CPI Microlith 605 had an average longevity more than twice that of all other VVI pacemakers. We also report on a pulse generator that lasted 26.3 years.
Mental Stress May Induce QT‐Interval Prolongation and T‐Wave Notching
Authors: Andrássy Gábor , Szabo Attila , Ferencz Gyöngyvér , Trummer Zsófia , Simon Eszter , Tahy Ádám 
Published: July 2007

Background: The effects of active and passive mental stress (PMS) on the QT interval were studied by using an intraindividual regression method of QT‐interval correction for heart rate. Methods: Thirty healthy males (age 21.2 ± 1.8 years) performed a mental arithmetic for 1 minute, which was considered as active mental stress (AMS) because of the performance requirement. A 1‐minute unpleasant video clip was used for PMS. Two baseline and two (an early and a late) ECGs were prepared in both mental stress periods. The individual QT–RR relationship was assessed by linear regression analysis of 7–15 (11.0 ± 1.9) controlled QT–RR data pairs, also obtained from ECGs gained during a successive set of 9 isometric stretching exercises. Results: Heart rate has increased significantly at both measurements in response to AMS (P < 0.0001), but not in response to passive stress. QTc significantly prolonged early in AMS (P = 0.0004), then normalized by the end of the period. During PMS, no significant QTc changes were observed. The evolution of bifid T waves was noted in 14 subjects: 8 presented bifid T waves during both AMS and exercise, and 6 during only exercise. Conclusions: AMS and PMS elicit different cardiovascular reactions. Our results indicate that changes in the autonomic tone, probably abrupt sympathetic predominance, may cause QTc prolongation and bifid T waves. This suggests that besides stress quality and intensity, the dynamics of stress application and perception also influence repolarization.
A review of catchment management in the new context of drinking water safety plans
Authors: Keirle Robert , Hayes Colin 
Published: July 2007

AbstractBy managing a catchment effectively, the range and amount of contaminants entering waters used for public water supply can be reduced, with resultant benefits for both water companies and consumers. Consequently, catchment management is increasingly being recognised as being at the heart of the water environment. An overview of current and previous catchment management initiatives is given, along with the European Landscape Convention, which could be used as a vehicle for the implementation of a national catchment management strategy. The adoption of the drinking water safety plan approach is strongly advocated by the World Health Organisation, and effective catchment management underpins this approach. Effective management of our catchments will also make a significant contribution to meeting our obligations under the Water Framework Directive, by helping to address the serious issue of diffuse pollution from agriculture.
Estimating Attenuation of Ultraviolet Radiation in Streams: Field and Laboratory Methods
Authors: Belmont Patrick , Hargreaves Bruce R. , Morris Donald P. , Williamson Craig E. 
Published: July 2007

AbstractWe adapted and tested a laboratory quantitative filter pad method and field‐based microcosm method for estimating diffuse attenuation coefficients (Kd) of ultraviolet radiation (UVR) for a wide range of stream optical environments (Kd320 = 3–44 m−1). Logistical difficulties of direct measurements of UVR attenuation have inhibited widespread monitoring of this important parameter in streams. Suspended sediment concentrations were manipulated in a microcosm, which was used to obtain direct measurements of diffuse attenuation. Dissolved and particulate absorption measurements of samples from the microcosm experiments were used to calibrate the laboratory method. Conditions sampled cover a range of suspended sediment (0–50 mg L−1) and dissolved organic carbon concentrations (1–4 mg L−1). We evaluated four models for precision and reproducibility in calculating particulate absorption and the optimal model was used in an empirical approach to estimate diffuse attenuation coefficients from total absorption coefficients. We field‐tested the laboratory method by comparing laboratory‐estimated and field‐measured diffuse attenuation coefficients for seven sites on the main stem and 10 tributaries of the Lehigh River, eastern Pennsylvania, USA. The laboratory‐based method described here affords widespread application, which will further our understanding of how stream optical environments vary spatially and temporally and consequently influence ecological processes in streams.
Fluoroquinolone Antibiotics Having the Potential to Interfere with Fluorescence‐Based Diagnosis†
Authors: Matchette L. Stephanie , Agrawal Anant , Pfefer T. Joshua 
Published: July 2007

AbstractFluorescence, both intrinsic and exogenously induced, is being used for diagnosis of abnormal tissue. Excitation wavelengths used by these methods range from 320 to 450 nm. The presence of absorbing or fluorescing drugs is rarely taken into account by practitioners of fluorescence diagnosis and has the potential to yield false‐positive or false‐negative results. Our aim is to quantify this potential by (1) comparing the quantum yield of fluoroquinolone antibiotics to those of known tissue fluorophores and (2) taking into account drug concentrations in the tissue during treatment. Quantum yields are determined relative to a working standard of Rhodamine 6G in ethanol. The working standard was calibrated against a fluorescein standard. We concentrated our initial efforts on (1) the fluoroquinolone antibiotics, ciprofloxacin, norfloxacin and ofloxacin and (2) the intrinsic tissue fluorophores, NADH, FAD and protoporphyrin IX. When ciprofloxacin, norfloxacin and ofloxacin were excited at wavelengths 310–390 nm, emission occurred from 350 to 650 nm with quantum yields ranging from 0.03 to 0.3. Quantum yields for intrinsic fluorophores excited at their peak absorption wavelengths were 0.02 (NADH, 340 nm), 0.035 (FAD, 450 nm) and 0.087 (protoporphyrin IX, 408 nm). A review of the literature shows that these fluoroquinolones have a large volume of distribution and can be found in high concentrations in almost every organ during a treatment regimen. The product of the drug tissue concentration and quantum yield, which we term the fluorescence effective concentration, is such that it is likely these fluoroquinolones will interfere during fluorescence diagnosis techniques.
Helicobacter pylori infection in hepatic encephalopathy: Relationship to plasma endotoxins and blood ammonia
Authors: Abdel‐Hady Hassan , Zaki Ali , Badra Gamal , Lotfy Mahmoud , Selmi Carlo , Giorgini Alessia , El‐Sayed Mohamed , Badr Reda 
Published: July 2007

Background/Aim:  Hepatic encephalopathy (HE) is frequently observed in patients with advanced liver disease and manifests a wide variety of neuropsychiatric signs and symptoms. Ammonia toxicity and bacterial endotoxins have been suggested as key determinants of HE onset whereas a role for Helicobacter pylori infection has not been established. We investigated the correlation between H. pylori infection and HE severity (evaluated through functional tests) in 60 outpatients with established liver cirrhosis and 20 non‐cirrhotic controls.Methods:  Fasting arterial blood ammonia, plasma endotoxins, and H. pylori infection status were investigated in all subjects.Results:  H. pylori infection was documented in 35/60 (58%) patients and in 6/20 (30%) controls (P = 0.039). Significant differences were observed between patients with and withoutHE for age, presence of ascites, fasting arterial blood ammonia, plasma endotoxin, and H. pylori infection. Further, a significant increase in fasting arterial blood ammonia and plasma endotoxin was associated with H. pylori infection in cirrhotic patients. Last, medical treatment of H. pylori infection led to a significant decrease in HE severity and fasting arterial blood ammonia levels.Conclusion:  In conclusion, we submit that H. pylori infection might, in fact, play a role in increasing the circulating levels of ammonia and endotoxins in cirrhotic patients, thus facilitating the onset of HE.
The α-tubulin gene family in wheat (Triticum aestivum L.) and differential gene expression during cold acclimation
Authors: Ridha Farajalla Mohammed , Gulick Patrick J. 
Published: July 2007

The α-tubulins and β-tubulins are the major constituents of microtubules, which have been recognized as important structural elements in cell growth and morphogenesis, and, recently, for their role in regulation and signal transduction. We have identified 15 full-length cDNAs for the members of the α-tubulin gene family in hexaploid bread wheat (Triticum aestivum L.). The genes were clustered into 5 homeologous groups of 3 genes. Representatives of the 5 homeologous groups were mapped to different chromosome arms, and the genome of origin was determined for each gene. Changes in mRNA levels were observed for the paralogous members of the gene family during cold acclimation. Three members of the family had initial decreases in mRNA levels in response to cold treatment, which were followed by increases, each with a different pattern of reinduction. One gene-family member showed increased mRNA for up to 14 d during cold acclimation and had decreased levels after 36 d of cold treatment; a fifth paralogous member of the gene family had slowly declining mRNA levels up to 36 d. Subtle differences in the level of gene expression among homeologs and large differences among paralogs were detected by comparing the relative abundance of wheat α-tubulin expressed sequence tags (ESTs) in public databases.
Normalization of the calcineurin pathway underlies the regression of hypertensive hypertrophy induced by Na+/H+exchanger-1 (NHE-1) inhibitionThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Ennis Irene L. , Garciarena Carolina D. , Escudero Eduardo M. , Pérez Néstor G. , Dulce Raúl A. , Camilión de Hurtado María C. , Cingolani Horacio E. 
Published: July 2007

Na+/H+exchanger-1 (NHE-1) inhibition induces cardiac hypertrophy regression and (or) prevention in several experimental models, although the intracellular events involved remain unclarified. We aimed to determine whether the calcineurin/NFAT pathway mediates this effect of NHE-1 inhibitors. Spontaneously hypertensive rats (SHR) with cardiac hypertrophy were treated with the NHE-1 inhibitors cariporide and BIIB723 for 30 days. Wistar rats served as normotensive controls. Their hearts were studied by echocardiography, immunoblotting, and real-time RT-PCR. Cytoplasmic Ca2+and calcineurin Aβ expression were measured in cultured neonatal rat ventricular myocytes (NRVM) stimulated with endothelin-1 for 24 h. NHE-1 blockade induced cardiac hypertrophy regression (heart mass/body mass = 3.63 ± 0.07 vs. 3.06 ± 0.05 and 3.02 ± 0.13 for untreated vs. cariporide- and BIIB723-treated SHR, respectively; p < 0.05) and decreased myocardial brain natriuretic peptide, calcineurin Aβ, and nuclear NFAT expressions. Echocardiographic evaluation demonstrated a reduction in left ventricular wall thickness without changes in cavity dimensions or a significant decrease in blood pressure. NHE-1-inhibitor treatment did not affect myocardial stiffness or endocardial shortening, but increased mid-wall shortening, suggesting that a positive inotropic effect develops after hypertrophy regression. Cariporide normalized the increased diastolic Ca2+and calcineurin Aβ expression observed in ET-1-stimulated NRVM. In conclusion, our data suggest that inactivation of calcineurin/NFAT pathway may underlie the regression of cardiac hyper-trophy induced by NHE-1 inhibition.
Visualization and grading of regional ischemia in pigs in vivo using near-infrared and thermal imagingThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute.
Authors: Manley Darren M. , Xiang Bo , Kupriyanov Valery V. 
Published: July 2007

Reductions in regional coronary flow result in tissue deoxygenation and decrease in surface temperature, changes detectable by near-infrared spectroscopic (NIRS) and thermal imaging, respectively. In anesthetized open-chest pigs, an inflatable occluder and flow probe were placed around the left anterior descending artery. Gated NIRS and nongated thermal images were acquired at baseline, partial (17% and 50%), and complete occlusion and reflow. At each step, dobutamine was infused (10 μg·min–1·kg–1) for 7–9 min to increase blood pressure and flow. Changes in the oxygen saturation parameter, rate of indocyanine green flow tracer passage, and the surface temperature were correlated with the measured left anterior descending artery flow. Location and sizes of the areas of reduced oxygenation, indocyanine green uptake, and temperature were similar. Decrease in the coronary flow to 50% and 17% of baseline resulted in progressive decrease in the above parameters, whereas increase in flow from 75% to ~250% achieved by dobutamine and reactive hyperemia did not significantly change them. Dobutamine increased total and epicardial flow in ischemic areas and increased subepicardial oxygenation. NIRS and thermal imaging provide epicardial maps of oxygen saturation and perfusion that reveal ischemic areas. Combination of these techniques may be useful in the coronary artery bypass graft (CABG) surgery setting.
Breast Cancer Antiestrogen Resistance-3 Expression Regulates Breast Cancer Cell Migration through Promotion of p130Cas Membrane Localization and Membrane Ruffling
Authors: Schrecengost Randy S. , Riggins Rebecca B. , Thomas Keena S. , Guerrero Michael S. , Bouton Amy H. 
Published: July 2007

Abstract
Antiestrogens such as tamoxifen are widely used in the clinic to treat estrogen receptor–positive breast tumors. Resistance to tamoxifen can occur either de novo or develop over time in a large proportion of these tumors. Additionally, resistance is associated with enhanced motility and invasiveness in vitro. One molecule that has been implicated in tamoxifen resistance, breast cancer antiestrogen resistance-3 (BCAR3), has also been shown to regulate migration of fibroblasts. In this study, we investigated the role of BCAR3 in breast cancer cell migration and invasion. We found that BCAR3 was highly expressed in multiple breast cancer cell lines, where it associated with another protein, p130Cas (also known as breast cancer antiestrogen resistance-1; BCAR1), that plays a role in both tamoxifen resistance and cell motility. In cells with relatively low migratory potential, BCAR3 overexpression resulted in enhanced migration and colocalization with p130Cas at the cell membrane. Conversely, BCAR3 depletion from more aggressive breast cancer cell lines inhibited migration and invasion. This coincided with a relocalization of p130Cas away from the cell membrane and an attenuated response to epidermal growth factor stimulation that was characterized by a loss of membrane ruffles, decreased migration toward EGF, and disruption of p130Cas/Crk complexes. Based on these data, we propose that the spatial and temporal regulation of BCAR3/p130Cas interactions within the cell is important for controlling breast cancer cell motility. [Cancer Res 2007;67(13):6174–82]
Antitumor Activity of PR-171, a Novel Irreversible Inhibitor of the Proteasome
Authors: Demo Susan D. , Kirk Christopher J. , Aujay Monette A. , Buchholz Tonia J. , Dajee Maya , Ho Mark N. , Jiang Jing , Laidig Guy J. , Lewis Evan R. , Parlati Francesco , Shenk Kevin D. , Smyth Mark S. , Sun Congcong M. , Vallone Marcy K. , Woo Tina M. , Molineaux Christopher J. , Bennett Mark K. 
Published: July 2007

Abstract
Clinical studies with bortezomib have validated the proteasome as a therapeutic target for the treatment of multiple myeloma and non-Hodgkin's lymphoma. However, significant toxicities have restricted the intensity of bortezomib dosing. Here we describe the antitumor activity of PR-171, a novel epoxyketone-based irreversible proteasome inhibitor that is currently in clinical development. In comparison to bortezomib, PR-171 exhibits equal potency but greater selectivity for the chymotrypsin-like activity of the proteasome. In cell culture, PR-171 is more cytotoxic than bortezomib following brief treatments that mimic the in vivo pharmacokinetics of both molecules. Hematologic tumor cells exhibit the greatest sensitivity to brief exposure, whereas solid tumor cells and nontransformed cell types are less sensitive to such treatments. Cellular consequences of PR-171 treatment include the accumulation of proteasome substrates and induction of cell cycle arrest and/or apoptosis. Administration of PR-171 to animals results in the dose-dependent inhibition of the chymotrypsin-like proteasome activity in all tissues examined with the exception of the brain. PR-171 is well tolerated when administered for either 2 or 5 consecutive days at doses resulting in &gt;80% proteasome inhibition in blood and most tissues. In human tumor xenograft models, PR-171 mediates an antitumor response that is both dose and schedule dependent. The antitumor efficacy of PR-171 delivered on 2 consecutive days is stronger than that of bortezomib administered on its clinical dosing schedule. These studies show the tolerability, efficacy, and dosing flexibility of PR-171 and provide validation for the clinical testing of PR-171 in the treatment of hematologic malignancies using dose-intensive schedules. [Cancer Res 2007;67(13):6383–91]
Sodium Selenite Induces Superoxide-Mediated Mitochondrial Damage and Subsequent Autophagic Cell Death in Malignant Glioma Cells
Authors: Kim Eun Hee , Sohn Seonghyang , Kwon Hyuk Jae , Kim Seung U. , Kim Min-Jung , Lee Su-Jae , Choi Kyeong Sook 
Published: July 2007

Abstract
Malignant gliomas are resistant to various proapoptotic therapies, such as radiotherapy and conventional chemotherapy. In this study, we show that selenite is preferentially cytotoxic to various human glioma cells over normal astrocytes via autophagic cell death. Overexpression of Akt, survivin, XIAP, Bcl-2, or Bcl-xL failed to block selenite-induced cell death, suggesting that selenite treatment may offer a potential therapeutic strategy against malignant gliomas with apoptotic defects. Before selenite-induced cell death in glioma cells, disruption of the mitochondrial cristae, loss of mitochondrial membrane potential, and subsequent entrapment of disorganized mitochondria within autophagosomes or autophagolysosomes along with degradation of mitochondrial proteins were noted, showing that selenite induces autophagy in which mitochondria serve as the main target. At the early phase of selenite treatment, high levels of superoxide anion were generated and overexpression of copper/zinc superoxide dismutase or manganese superoxide dismutase, but not catalase, significantly blocked selenite-induced mitochondrial damage and subsequent autophagic cell death. Furthermore, treatment with diquat, a superoxide generator, induced autophagic cell death in glioma cells. Taken together, our study clearly shows that superoxide anion generated by selenite triggers mitochondrial damage and subsequent mitophagy, leading to irreversible cell death in glioma cells.[Cancer Res 2007;67(13):6314–24]