bluuebunny/crossref_metadata_2025 huggingface dataset:
School Context and the Effect of ESL Placement on Mexican‐Origin Adolescents' Achievement*
Authors: Callahan Rebecca , Wilkinson Lindsey , Muller Chandra
Published: September 2010

Objectives. Immigrant adolescents' academic achievement is crucial to our future economic stability, and Mexican‐origin linguistic minority youth in U.S. schools generally demonstrate lower levels of achievement. English as a Second Language (ESL) programs provide an institutional response to these students' needs, the effect of which may vary by the proportion of immigrant students in the school.

Measures. Using propensity score matching and data from the Adolescent Health and Academic Achievement Study (AHAA) and the National Longitudinal Study of Adolescent Health (Add Health), we estimate the effect of ESL placement on Mexican‐origin achievement for first‐, second‐, and third‐generation adolescents separately in schools with many and few immigrant students.

Results. The estimated effect of ESL placement varies by both immigrant concentration in the school and by students' generational status.

Conclusions. We find that ESL enrollment may be protective for second‐generation Mexican‐origin adolescents in high immigrant concentration schools, and may prove detrimental for first‐generation adolescents in contexts with few other immigrant students.
Higher Education Policy, Enrollment, and Income Inequality*
Authors: Bergh Andreas , Fink Günther
Published: September 2010

Objective. The objective of this article is to examine whether public expenditure on higher education has an effect on income inequality by increasing enrollment.

Methods. Combining data from the World Bank Development Indicators with data from the World Income Inequality Database version 2, we study the relation between government education expenditure and enrollment rates, as well as the relation between government education expenditure and the change in income inequality during the 1980s and the 1990s.

Results. We find that public expenditure on higher education has no positive effect on enrollment. Increased enrollment is mainly explained by higher GDP per capita. Using carefully selected Gini coefficients to ensure comparability over time, we do not find a robust relation between higher education expenditure and lower income inequality, contrary to some previous studies.

Conclusions. Government expenditure on higher education has very limited effects on enrollment and inequality. This finding, however, does not imply that there are no social benefits from such subsidies. For example, in countries where high marginal tax rates decrease the economic returns to education, governments may wish to compensate for this through subsidies.
THE EFFECT OF STATE TORT REFORMS ON CLAIM FILINGS
Authors: Schmit Joan T. , Browne Mark J. , Lee Han Duck
Published: September 2010

Abstract: Currently, the U.S. Congress continues to debate the passage of a tort reform bill. Such a bill is intended to limit legal liabilities, particularly as they relate to product accidents. While passage of a federal law in the 1990s remains difficult, many states found tort reform a successful proposition a decade earlier. The intent of this paper is to add to the discussion regarding the expected effects of tort law modifications by providing some background on the most widely enacted state tort reforms, presenting results from the literature on actual and expected effects of these reforms, and presenting new empirical evidence on the efficacy of these same reforms. The results indicate that caps on non‐economic damages and imposition of fines on frivolous litigation are negatively related to the rate of tort filings, while modification of joint and several liability demonstrates a positive relationship with the rate of tort filings, and reforms of the collateral source rule and imposition of punitive damages demonstrate no effect.
The Determinants of Corporate Entrepreneurial Intention within Small and Newly Established Firms
Authors: Fini Riccardo , Grimaldi Rosa , Marzocchi Gian Luca , Sobrero Maurizio
Published: September 2010

In this article, we study the determinants of corporate entrepreneurial intention (CEI) within small and newly established firms. Given that in these ventures, entrepreneurial activities usually occur as a result of individuals’ behaviors, the CEI of their founders is key to explaining these companies’ ability to become engaged in entrepreneurial actions. Building on the theory of planned behavior, we conceptualize how individual characteristics and contextual variables influence CEI. Our theoretical model of the micro–foundation of CEI is tested on a sample of 200 entrepreneurs, founders of 133 new technology–based firms.

Results show that CEI is influenced by situationally specific motivation, individual skills, and perceived environmental dynamism. Managerial implications are discussed.
Female Gender is Associated with a Better Outcome after Cardiac Resynchronization Therapy
Authors: LEYVA FRANCISCO , FOLEY PAUL W. X. , CHALIL SHAJIL , IRWIN NICK , SMITH RUSSELL E. A.
Published: September 2010

Background: Some studies have suggested that women respond differently to cardiac resynchronization therapy (CRT). We sought to determine whether female gender influences long‐term clinical outcome, symptomatic response as well as echocardiographic response after CRT.

Methods and Results: A total of 550 patients (age 70.4 ± 10.7 yrs [mean ± standard deviation]) were followed up for a maximum of 9.1 years (median: 36.2 months) after CRT‐pacing (CRT‐P) or CRT‐defibrillation (CRT‐D) device implantation. Outcome measure included mortality as well as unplanned hospitalizations for heart failure or major adverse cardiovascular events (MACE). Female gender predicted survival from cardiovascular death (hazard ratio [HR]: 0.52, P = 0.0051), death from any cause (HR: 0.52, P = 0.0022), the composite endpoints of cardiovascular death /heart failure hospitalizations (HR: 0.56, P = 0.0036) and death from any cause/hospitalizations for MACE (HR: 0.67, P = 0.0214). Female gender predicted death from pump failure (HR: 0.55, P = 0.0330) but not sudden cardiac death. Amongst the 322 patients with follow‐up echocardiography, left ventricular (LV) reverse remodelling (≥15% reduction in LV end‐systolic volume) was more pronounced in women (62% vs 44%, P = 0.0051). In multivariable Cox proportional hazards analyses, the association between female gender and cardiovascular survival was independent of age, LV ejection fraction, atrial rhythm, QRS duration, CRT device type, New York Heart Association (NYHA) class, and LV reverse remodelling (adjusted HR: 0.48, P = 0.0086). At one year, the symptomatic response rate (improvement by ≥1 NYHA classes or ≥25% increase in walking distance) was 78% for both women and men.

Conclusions: Female gender is independently associated with a lower mortality and morbidity after CRT. (PACE 2011; 82–88)
The Science of Pizza: The Molecular Origins of Cheese, Bread, and Digestion Using Interactive Activities for the General Public
Authors: Rowat Amy C. , Rosenberg Daniel , Hollar Kathryn A. , Stone Howard A.
Published: September 2010

Abstract:  We describe a presentation on the science of pizza, which is designed for the general public including children ages 6 and older. The presentation focuses on the science of making and digesting cheese and bread. We highlight 4 major scientific themes: (1) how macromolecules such as carbohydrates and proteins are composed of atoms and small molecules; (2) how macromolecules interact to form networks in bread and cheese; (3) how microbes contribute to the texture of bread; and (4) how enzymes break down macromolecules during digestion. Using live demonstrations and interactive exercises with children in the audience, we provide simple explanations of the scientific principles related to these themes that are essential for understanding how to make pizza, and what happens when we eat it. This general approach can be adapted to a variety of informal and classroom settings focused on sharing the excitement of scientific discovery and understanding with students and the public.
Les nouveaux marchés du travail: monopsone et faiblesse syndicale
Authors: ERICKSON Christopher L. , MITCHELL Daniel J. B.
Published: September 2010

Comment se peut‐il que partout les employeurs connaissent des pénuries de main‐d'æuvre de plus en plus graves? Pourquoi les salaires n'augmentent‐ils pas dans les économies en expansion? Selon les auteurs, le déclin du pouvoir syndical a permis aux employeurs d'avoir la haute main sur la détermination des salaires et conditions d'emploi, sur un marché du travail monopsonistique. Ils rejettent le modèle de la concurrence parfaite, avec ajustement de l'offre et de la demande, et considèrent que, loin d'être une curiosité pédagogique, celui du monopsone, avec inégalité du rapport de forces, se généralise. Il faut rétablir la capacité d'expression des salariés pour que les bons résultats macroéconomiques ne s'accompagnent d'effets pernicieux, comme les inégalités salariales ou l'affaiblissement des droits des travailleurs.
Más allá de códigos de conducta como el que rige para los proveedores de Nike
Authors: LOCKE Richard , KOCHAN Thomas , ROMIS Monica , QIN Fei
Published: September 2010

¿Qué pueden hacer los códigos empresariales de buena conducta en pro de la vigilancia del cumplimiento de las normas internacionales del trabajo y de la mejora de las condiciones de trabajo en las cadenas de aprovisionamiento mundiales? Para contestar a esta pregunta, lo primero que hacen los autores es resumir las averiguaciones de un estudio de las condiciones de trabajo en 800 fábricas de cincuenta y un países suministradoras de la empresa Nike Inc. y de dos monografías al respecto. Después analizan hasta qué punto encajan los códigos en el vasto mosaico de instituciones, políticas y prácticas destinadas a regular y mejorar las condiciones de trabajo, y abogan por un método gradual y complementario para realizar esta labor en las cadenas de aprovisionamiento mundiales. Esbozan las innovaciones que son necesarias en materia institucional y de investigación para poner a prueba estas ideas.
Disparidad salarial en los países de la OCDE
Authors: ATKINSON Anthony B.
Published: September 2010

Está muy extendida la opinión de que la desigualdad de ingresos ha aumentado en los países de la Organización de Cooperación y Desarrollo Económicos (OCDE) desde 1980. Se piensa que ello se debe al cambio tecnológico favorable al trabajo especializado, al crecimiento relativo de la demanda de trabajadores cualificados y a la competencia internacional que genera la globalización en perjuicio de los trabajadores sin cualificar. Pero esta explicación resulta ya muy endeble por sí sola, dado que la desigualdad se propaga a ritmos muy distintos en los países y que la disparidad avanza mucho más en la cúspide de la pirámide de ingresos. El autor estudia con nuevos ojos las tendencias de los últimos decenios y aporta explicaciones complementarias a la teoría de la carrera entre la tecnología y la cualificación profesional.
Evolución del derecho laboral. Análisis comparado de algunos regímenes
Authors: DEAKIN Simon , LELE Priya , SIEMS Mathias
Published: September 2010

Los autores trazan la evolución del derecho del trabajo en Alemania, Francia, Estados Unidos, India y Reino Unido con un nuevo conjunto de datos que permite calibrar los cambios jurídicos acaecidos a lo largo de un período. Su investigación esclarece la tesis de que la tradición jurídica de un ordenamiento condiciona el régimen laboral del mismo. En el nivel agregado se confirman algunas differencias entre los países de la esfera del derecho consuetudinario inglés (common law) y los que siguen la tradición del derecho civil, mientras que el panorama es más complejo en los diversos ámbitos del derecho laboral. Los autores estudian las posibilidades que brinda este método relativamente nuevo de medición para comprender las fuerzas que guían la evolución del derecho del trabajo.
El monopsonismo, metáfora del nuevo mercado de trabajo postsindical
Authors: ERICKSON Christopher L. , MITCHELL Daniel J.B.
Published: September 2010

¿Cómo es posible que, en todas las partes del mundo, en plena globalización, los empleadores sufran problemas cada vez más graves de escasez de mano de obra?¿Por qué no suben los salarios en las economías en expansión? La tesis que se defiende en este artículo es que, debido a la pérdida de fuerza de los sindicatos, los empleadores han tomado la delantera y establecen los salarios y otras condiciones de trabajo conforme a las reglas de un mercado laboral monopsonista. Los autores refutan el modelo de competencia perfecta, con su equilibrio entre oferta y demanda, y sostienen que, lejos de ser una curiosidad pedagógica, el monopsonismo y su desequilibrio en cuanto a la capacidad de negociación son una realidad muy extendida. Es necesario devolver la palabra a los trabajadores para subsanar consecuencias tan indeseables de los éxitos macroeconómicos como la desigualdad de ingresos y la pérdida de derechos laborales.
El trabajo infantil intermitente, su medición y su importancia
Authors: LEVISON Deborah , HOEK Jasper , LAM David , DURYEA Suzanne
Published: September 2010

Valiéndose de datos longitudinales de las zonas urbanas del Brasil, los autores indagan en la experiencia laboral de miles de niños de entre 10 y 16 años de edad en cuatro meses consecutivos de los decenios de 1980 y de 1990. La proporción de niños que estaban trabajando en algún momento del cuatrimestre era sustancialmente mayor de la que aparecía si sólo se estudiaba uno de los meses. Las tasas de empleo resultantes eran muy distintas, lo que ha inducido a los autores a calcular unos ≪multiplicadores de intermitencia≫. En conclusión, el empleo discontinuo es muy común y característico del trabajo infantil, por lo que ha de tenerse bien presente para averiguar con precisión los niveles reales de éste e identificar a los niños trabajadores.
Los modelos de empleo europeos, agitados por vientos de cambio
Authors: BOSCH Gerhard , RUBERY Jill , LEHNDORFF Steffen
Published: September 2010

Los ≪modelos nacionales de empleo≫ comprenden toda la gama de instituciones que influyen en la oferta, el uso y la demanda de fuerza de trabajo. A partir de un estudio sobre las tipologías al respecto, los autores averiguan cómo funcionan estos modelos en varios países y su capacidad respectiva de perdurar frente a las fuerzas que impulsan el cambio. Comparan la eficacia de los modelos en la salvaguardia de las condiciones de trabajo decentes, que se ven alteradas por la desreglamentación de los mercados de productos, el envejecimiento de la población y el progreso de las tasas de empleo de la mujer. A los Estados‐nación europeos cada vez les resulta más difícil reformar desde dentro sus modelos de empleo, por lo que hará falta fomentar unas políticas dinámicas en el plano de la Unión Europea.
The baboon model (Papio hamadryas) of fetal loss: maternal weight, age, reproductive history and pregnancy outcome
Authors: Schlabritz‐Loutsevitch Natalia E. , Moore Charleen M. , Lopez‐Alvarenga Juan Carlos , Dunn Betty G. , Dudley Donald , Hubbard Gene B.
Published: September 2010

Background  Several risk factors are associated with the incidence of human stillbirths. The prevention of stillbirths in women is a pressing clinical problem.

Methods  We reviewed 402 pathology records of fetal loss occurring in a large baboon (Papio spp.) colony during a 15‐year period. Clinical histories of 565 female baboons with one or more fetal losses during a 20‐year period were analyzed for weight, age, and reproductive history.

Results  Fetal loss was most common at term (35.57%) and preterm (28.61%) and less common in the first half of gestation (11.20%) and post‐term (5.22%). Greater maternal weight, older age, history of stillbirth and higher parity were independent predictors for stillbirth. An exponential increase in the incidence of fetal loss was observed beginning at age 14 years in baboons.

Conclusions  Fetal loss and maternal risk factors associated with stillbirths in baboons were similar to those documented in women.
Plant module size and dose of gall induction stimulus influence gall induction and galler performance
Authors: Flaherty Leah , Quiring Dan
Published: September 2010

Several different hypotheses attribute large variations in gall abundance and galler performance to variations in plant growth rate and/or module size. The plant vigor hypothesis (PVH) predicts that galler performance will be greatest on large, fast‐growing plant modules due to their large, rapidly dividing cells that allow them to make large galls, where survival and size of survivors are usually greater. The optimal module size hypothesis (OMSH) predicts that galler performance will be greatest on intermediate‐sized modules, based on a tradeoff between ease of gall induction on small modules and increased resource availability in large modules. Here, we evaluate predictions of the PVH and OMSH during a two‐year field study by examining gall induction and full gall development success, as well as subsequent galler performance in successfully developed galls, using a shoot galling adelgid, Adelges abietis, on white spruce Picea glauca. In addition, we tested whether increased dose of gall induction stimulus on different sized modules, achieved by observing differing A. abietis densities per bud, could increase the rate of successful gall induction, as predicted by the OMSH. Galls of A. abietis appeared to be induced by a dose‐dependent stimulus from fundatrices in spring. Furthermore, the critical stimulus dose required to induce a gall appeared to increase with shoot length. These findings support the OMSH and not the PVH. Galler performance (gall volume and the number of gallicolae that emerged from each gall) in successfully developed galls was positively related to shoot length, supporting both the PVH and OMSH. We conclude that the PVH represents one component of the more inclusive OMSH, which considers both ease of gall induction on different‐sized modules and the effect of plant module size on gall size.
Differences in aggression, activity and boldness between native and introduced populations of an invasive crayfish
Authors: Pintor Lauren M. , Sih Andrew , Bauer Marissa L.
Published: September 2010

Aggressiveness, along with foraging voracity and boldness, are key behavioral mechanisms underlying the competitive displacement and invasion success of exotic species. However, do aggressiveness, voracity and boldness of the invader depend on the presence of an ecologically similar native competitor in the invaded community? We conducted four behavioral assays to compare aggression, foraging voracity, threat response and boldness to forage under predation risk of multiple populations of exotic signal crayfish Pacifastacus leniusculus across its native and invaded range with and without a native congener, the Shasta crayfish P. fortis. We predicted that signal crayfish from the invaded range and sympatric with a native congener (IRS) should be more aggressive to outcompete a close competitor than populations from the native range (NR) or invaded range and allopatric to a native congener (IRA). Furthermore, we predicted that IRS populations of signal crayfish should be more voracious, but less bold to forage under predation risk since native predators and prey likely possess appropriate behavioral responses to the invader. Contrary to our predictions, results indicated that IRA signal crayfish were more aggressive towards conspecifics and more voracious and active foragers, yet also bolder to forage under predation risk in comparison to NR and IRS populations, which did not differ in behavior. Higher aggression/voracity/boldness was positively correlated with prey consumption rates, and hence potential impacts on prey. We suggest that the positive correlations between aggression/voracity/boldness are the result of an overall aggression syndrome. Results of stream surveys indicated that IRA streams have significantly lower prey biomass than in IRS streams, which may drive invading signal crayfish to be more aggressive/voracious/bold to acquire resources to establish a population.
Enrichment can damp population cycles: a balance of inflexible and flexible interactions
Authors: Mougi Akihiko , Nishimura Kinya
Published: September 2010

Destabilization of one predator–one prey systems with an increase in nutrient input has been viewed as a paradox. We report that enrichment can damp population cycles by a food‐web structure that balances inflexible and flexible interaction links (i.e. specialist and generalist predators). We modeled six predator–prey systems involving three or four species in which the predators practice optimal foraging based on prey profitability determined by handling time. In all models, the balance of interaction links simultaneously decreased the amplitude of population oscillations and increased the minimum density with increasing enrichment, leading to a potential theoretical resolution of the paradox of enrichment in non‐equilibrium dynamics. The stabilization mechanism was common to all of the models. Important previous studies on the stability of food webs have also demonstrated that a balance of interaction strengths stabilizes systems, suggesting a general rule of ecosystem stability.
The cost of males in Daphnia pulex
Authors: Wolinska Justyna , Lively Curtis M.
Published: September 2010

Sex is paradoxical, because asexuals should replace their sexual ancestors by avoiding the demographic cost of producing males (hereafter referred to as the cost‐of‐males). Despite the large body of theoretical and empirical work dealing with the paradox of sex, the cost‐of‐males assumption has been rarely tested. In the present study, we tested the cost‐of‐males assumption in the cladoceran Daphnia pulex. Populations of this species consist of both cyclically parthenogenetic (i.e. sexuals) and obligately parthenogenetic (i.e. asexuals) lineages. In addition, some of the asexual lineages produce only female offspring, whereas others produce functional males, which can mate with sexual females. We compared the reproductive investment of sexuals, male‐producing asexuals, and non‐male‐producing asexuals when raised separately under various environmental conditions. We also determined the outcome of competition between pair‐wise combinations of these reproductive modes. The cost of males was evident when sexual and asexual females were raised separately: sexuals produced fewer female offspring. However, there was no cost of males when reproductive modes were raised in pairs, as sexuals won the competition with asexuals. Our results directly relate to the field conditions experienced by D. pulex. Sexuals might suffer the cost of males at the beginning of the season, when resource competition is low; but when conditions deteriorate as the population approaches carrying capacity, sexuals seem to be better competitors in spite of male production.
Interactive effects of predators and a pesticide on aquatic communities
Authors: Relyea Rick A. , Hoverman Jason T.
Published: September 2010

Chemical contaminants are ubiquitous in nature and a major goal of ecologists has been to understand and predict their impacts on natural communities. While direct toxic effects can be garnered from single‐species laboratory studies, the full suite of possible effects can only be observed when organisms are embedded within a community. In this study, we manipulated the concentration of malathion (a broad‐spectrum insecticide) to determine the impacts on aquatic communities containing phytoplankton, periphyton, and 27 species of animals (16 zooplankton, 5 snails, 3 tadpoles and 3 predatory insects). Using relatively low concentrations (0.13 to 0.46 mg l−1), we found important direct (and interactive) effects of predators and malathion on the food web as well as a number of apparent density‐ and trait‐mediated indirect effects. Malathion initiated an indirect effect by decreasing zooplankton diversity and abundance, which propagated an increase in phytoplankton, a decrease in periphyton, and a subsequent decrease in the growth of leopard frog tadpoles. There also was an apparent trait‐mediated indirect effect whereby increased amounts of the pesticide reduced predation rates on amphibians without affecting the survival of the primary amphibian predator (larval Anax dragonflies). In contrast, snail survival and growth was unaffected by the pesticide but there were strong, species‐specific effects from their primary predator (adult Belostoma water bugs). This is one of few studies to examine the impacts of malathion on aquatic communities across a range of concentrations, despite the fact that it is currently the most commonly applied insecticide in the United States, it is applied around the world, and it can be legally directly sprayed over aquatic habitats to control the mosquitoes that carry malaria and West Nile virus. Our results suggest several mechanisms by which a wide variety of pesticides with similar modes of action might impact aquatic communities.
Tumor necrosis factor‐α stimulates gingival epithelial cells to release high mobility‐group box 1
Authors: Morimoto Y. , Kawahara K‐I. , Tancharoen S. , Kikuchi K. , Matsuyama T. , Hashiguchi T. , Izumi Y. , Maruyama I.
Published: September 2010

Background and Objective: High‐mobility‐group box 1 functions as a late‐phase inflammatory mediator. It can be released extracellularly by macrophages and necrotic cells through lipopolysaccharide and tumor necrosis factor‐α. The objective of this study was to clarify the source of high‐mobility‐group box 1 in chronic periodontitis tissues and tumor necrosis factor‐α‐stimulated gingival epithelial cells, and subsequently elucidate its inducible inflammatory pathway.

Material and Methods: Chronic periodontitis and healthy gingival sections were stained for high‐mobility‐group box 1 by immunohistochemistry and immunofluorescence. The amounts of high‐mobility‐group box 1 released into the gingival crevicular fluid and supernatants from gingival epithelial cells stimulated by tumor necrosis factor‐α were examined by western blot. The phosphorylation of mitogen‐activated protein kinases (MAPKs) in gingival epithelial cells was also examined.

Results: High‐mobility‐group box 1 was detected in the cytoplasm and nucleus of gingival epithelial cells with periodontitis. Western blotting revealed a significant increase in high‐mobility‐group box 1 expression in the gingival crevicular fluid from periodontitis patients. High‐mobility‐group box 1 production in gingival epithelial cells was increased following stimulation with tumor necrosis factor‐α. The molecular dialogue between tumor necrosis factor‐α and gingival epithelial cells involved modulation of the activities of p38MAPK, Jun N‐terminal kinase and p44/42. Interestingly, only phosphorylation of p38MAPK contributed to more than half of the signaling initiated by tumor necrosis factor‐α‐elicited high‐mobility‐group box 1 release.

Conclusion: High‐mobility‐group box 1 is continuously released from the gingival epithelial cells modulated by tumor necrosis factor‐α. These findings imply that high‐mobility‐group box 1 expression and possibly p38MAPK constitute important features in periodontitis.
Hydrogen sulfide inhibits cell proliferation and induces cell cycle arrest via an elevated p21Cip1 level in Ca9‐22 cells
Authors: Takeuchi H. , Setoguchi T. , Machigashira M. , Kanbara K. , Izumi Y.
Published: September 2010

Background and Objective:  Volatile sulfur compounds such as hydrogen sulfide (H2S) and methyl mercaptan (CH3SH) are the main causes of oral malodor. However, the physiological functions of H2S have not been investigated in oral tissues. The aim of this study was to evaluate the effect of H2S on cell proliferation and the cell cycle in oral epithelial‐like cells.

Material and Methods:  Ca9‐22 cells were used in this study. Cells were cultured in 5% CO2/95% air with (5 or 10 ng/mL) or without H2S. DNA synthesis was measured using a 5‐bromo‐2‐deoxyuridine enzyme‐linked immunosorbent assay. The cell cycle was analyzed using a flow cytometer. The expressions of phosphorylated retinoblastoma protein (Rb), p21Cip1 and p27Kip1 were evaluated by western blotting.

Results:  Exposure to 5 and 10 ng/mL of H2S significantly decreased DNA synthesis (p < 0.05). Cell cycle analysis also showed that exposure to both concentrations of H2S significantly increased the proportion of cells in G1 phase (p < 0.001) and significantly decreased the proportion of cells in S phase (p < 0.01). Western blotting showed that Rb phosphorylation was reduced and p21Cip1 was enhanced by exposure to H2S.

Conclusion:  The results indicated that H2S inhibits cell proliferation and induces cell cycle arrest via the expression of p21Cip1 in Ca9‐22 cells.
Seasonal variations in the nycthemeral rhythm of plasma melatonin in the camel (Camelus dromedarius)
Authors: El Allali K. , Achaaban M. R. , Vivien‐Roels B. , Bothorel B. , Tligui N. S. , Pévet P.
Published: September 2010

Abstract: Seasonal changes in the pattern of plasma melatonin were investigated in two groups of camels (Camelus dromedarius): 11 adult and six young camels. Animals were subjected to the outdoor conditions of a desert environment. Blood samples were taken at regular intervals of about 3 hr (added to particular samples at 1 hr before then 30 min and 1 hr after sunset, and 1 hr before and 1 hr after sunrise) for 24 hr at both solstices and equinoxes of the year. The plasma melatonin levels steeply increased soon after sunset and remained elevated throughout all the night. Then, melatonin concentrations progressively declined shortly before sunrise and returned to daytime basal levels 1 hr later. There was no seasonal variation in the amplitude or in the offset of the melatonin peak or in the daytime basal levels. The onset of the nocturnal peak was delayed by 2 hr in June at the summer solstice (P < 0.05), which can be related to the changes in night length between the two solstices. A significant effect of age was observed in all seasons. Melatonin levels were higher in the young camel group (fall equinox:P < 0.001; spring equinox:P < 0.01; winter solstice:P < 0.01; summer solstice:P < 0.05). The pattern of melatonin secretion in the camel showed a significant seasonal variation parallel to the photoperiodic changes of the year. The observed decline of melatonin levels during an extra‐light pulse in the middle of the night indicates the light control of melatonin synthesis. It is not yet known if, in this low latitude desert region, the seasonal breeding period of the camel is cued by the photoperiod. The data obtained, however, clearly demonstrate that the camel has the capacity to follow and to integrate photoperiodic changes through melatonin changes.
Melatonin reduces oxidative stress and increases gene expression in the cerebral cortex and cerebellum of aluminum‐exposed rats
Authors: Esparza José L. , Gómez Mercedes , Rosa Nogués M. , Paternain José L. , Mallol Jordi , Domingo José L.
Published: September 2010

Abstract:  The pro‐oxidant activity of aluminum (Al), the protective role of exogenous melatonin, as well as the mRNA levels of some antioxidant enzymes, were determined in cortex and cerebellum of rats following exposure to Al and/or melatonin. Two groups of male rats received intraperitoneal injections of Al lactate or melatonin at doses of 7 mg Al/kg/day and 10 mg/kg/day, respectively, for 11 wk. A third group of animals received concurrently Al lactate (7 mg Al/kg/day) plus melatonin (10 mg/kg/day) during the same period. A fourth group of rats was used as control. At the end of the treatment, the cerebral cortex and cerebellum were removed and processed to examine the following oxidative stress markers: glutathione transferase (GST), reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), glutathione reductase, glutathione peroxidase (GPx), catalase (CAT), thiobarbituric acid reactive substances (TBARS), as well as protein content. Moreover, gene expression of Cu‐ZnSOD, MnSOD, GPx and CAT was evaluated by real‐time RT‐PCR. On the other hand, Al, Fe, Mn, Cu and Zn concentrations were determined in cortex and cerebellum of rats. Oxidative stress was promoted in both neural regions following Al administration, resulting from the pro‐oxidant activity related with an increase in tissue Al concentrations. In contrast, melatonin exerted an antioxidant action which was related with an increase in the mRNA levels of the antioxidant enzymes evaluated. The results of the present investigation emphasize the potential use of melatonin as a supplement in the therapy of neurological disorders in which oxidative stress is involved.
Protective effect of melatonin on ascorbate‐Fe2+ lipid peroxidation of polyunsaturated fatty acids in rat liver, kidney and brain microsomes: a chemiluminescence study
Authors: Leaden Patricio J. , Catalá Angel
Published: September 2010

Abstract:  Melatonin (N‐acetyl‐5‐methoxytryptamine), the main secretory product of the pineal gland, is a free radical scavenger that has been found to protect against lipid peroxidation in many experimental models. In the present study the effect of melatonin on lipid peroxidation of long chain polyunsaturated fatty acids located in rat liver, kidney and brain microsomes was determined using gas chromatography and a chemiluminescence assay. In vitro assays showed that after incubation of rat liver, kidney or brain microsomes in an ascorbate‐Fe++ system, at 37°C for 180 min, the total cpm originated from light emission (chemiluminescence) was found to be lower in those membranes incubated in the presence of melatonin. The incubation of rat liver, kidney or brain microsomes in the presence of ascorbate‐Fe2+ resulted in lipid‐peroxidation of membranes as evidenced by light emission and decrease of docosahexaenoic acid 22:6 n‐3 and arachidonic acid 20:4 n‐6. In the presence of melatonin (0.5, 1.0, 1.5 mm), light emission percent inhibition of microsomes was: (liver – 3.33, 9.98, 39.40) (kidney – 46.79, 61.88, 68.36) and (brain – 33.36, 28.89, 43.32). Not all fatty acids were equally protected after the addition of melatonin to the incubation medium. Our results indicate a selective protection of C20:4 n6 and C22:6 n3 by melatonin during non‐enzymatic lipid peroxidation of rat liver, kidney and brain microsomes.
Interactions between melatonin and nicotinamide nucleotide: NADH preservation in cells and in cell‐free systems by melatonin
Authors: Tan Dun‐Xian , Manchester Lucien C. , Sainz Rosa M. , Mayo Juan C. , Leon Josefa , Hardeland Ruediger , Poeggeler Burkhard , Reiter Russel J.
Published: September 2010

Abstract:  Interactions of melatonin and nicotinamide adenine dinucleotide (NADH) have been studied in different experimental models including NADH‐promoted oxyhemoglobin oxidation, vanadate‐induced NADH oxidation and paraquat‐induced NADH depletion in cultured PC12 cells. Our findings indicate that melatonin preserves NADH levels under oxidative stress both in cell‐free systems and in cultured PC12 cells. These interactions likely involve electron donation by melatonin and reduction of the NAD radical. As a result, the NAD radical is recycled to NADH and melatonin is oxidized to N1‐acetyl‐N2‐formyl‐5‐methoxykynuramine (AFMK). NADH is a central molecule at the crossroads between energy metabolism and the antioxidant defense system in organisms. Recycling of NADH by melatonin might improve the efficiency of NADH as an energy carrier and as an antioxidant. Interactions between melatonin and NADH may be implicated in mitochondrial metabolism.
Positive relationship between melatonin receptor type 1B polymorphism and rheumatoid factor in rheumatoid arthritis patients in the Korean population
Authors: Ha Eunyoung , Choe Bong‐Keun , Jung Kyung Hee , Yoon Seo Hyun , Park Hae Jeong , Park Hun Kuk , Yim Sung‐Vin , Chung Joo‐Ho , Bae Hyun‐Su , Nam Min , Baik Hyung Hwan , Hong Seung‐Jae
Published: September 2010

Abstract:  Melatonin is reported to be an anti‐inflammatory agent. No genetic study concerning the association between melatonin and inflammatory disease has yet been reported. Here we performed a polymorphism study on the melatonin receptor type 1B (MTNR1B) in Korean rheumatoid arthritis (RA) patients and controls. The polymorphism of MTNR1B located in 3′‐untranslated region (rs 1562444) was selected for its higher rate of heterozygosity among other single nucleotide polymorphisms (SNPs) in both MTNR1A and MTNR1B genes and investigated in RA patients (n = 173) and healthy controls (n = 195) by polymerase chain reaction‐restriction fragment length polymorphism assay using NlaIII restriction enzyme. No statistically significant difference in either genotype distribution or allele frequency was observed between RA patients and controls. The genotype distributions and allele frequencies of rheumatoid factor negative [RF(−)] patients were similar to those of controls. However, statistical analysis of genotype revealed a significant association (χ2 = 6.42, P = 0.04) is present between RF(+) and MTNR1B SNP (rs 1562444). Although no statistically significant difference in allele frequency between RF(+) and controls was observed (χ2 = 2.75, P = 0.10), the results might suggest that MTNR1B SNP (rs 1562444) is associated with the presence of RF in RA. This is the first study, to our knowledge, to report a positive genetic relationship between melatonin and RA.
Melatonin restores the cytochrome oxidase reactivity in the nodose ganglia of acute hypoxic rats
Authors: Chang Hung‐Ming , Tseng Chi‐Yu , Wei I‐Hua , Lue June‐Horng , Wen Chen‐Yuan , Shieh Jeng‐Yung
Published: September 2010

Abstract:  This study aimed to elucidate whether melatonin would exert beneficial effects on the neuronal functions of the nodose ganglion (NG) following acute hypoxic insult. The cytochrome oxidase (COX) and the nicotinamine adenine dinucleotide phosphate diaphorase (NADPH‐d) histochemistry along with the nitric oxide synthase (NOS) immunofluorescence were used to examine the metabolic stage and nitric oxide production in nodose neurons respectively. Adult rats were injected intraperitoneally with melatonin at 5 or 100 mg/kg. Hypoxia was achieved by placing the rats into an altitude chamber (PO2 = 43 torr) for 4 hr. The results show that in normal untreated rats, nearly all and about 43% of the NG neurons displayed COX and NOS/NADPH‐d reactivities with various staining intensities respectively. However, COX reactivity was drastically decreased while NOS/NADPH‐d reactivity was significantly upregulated following hypoxia treatment. In melatonin pretreated rats, the hypoxia‐induced reduction of COX reactivity was obviously prevented and the augmentation of NOS/NADPH‐d reactivity was successfully suppressed. The deficit in the metabolic stage and the over‐activation of NOS would contribute to the generation of oxidative stress. By effectively preventing the metabolic disruption, melatonin may have potential utility in therapeutic treatment of neuronal dysfunctions where oxidative stress is a participant.
Melatonin and vitamin C increase umbilical blood flow via nitric oxide‐dependent mechanisms
Authors: Thakor Avnesh S. , Herrera Emilio A. , Serón‐Ferré Maria , Giussani Dino A.
Published: September 2010

Abstract:  Inadequate umbilical blood flow leads to intrauterine growth restriction, a major killer in perinatal medicine today. Nitric oxide (NO) is important in the maintenance of umbilical blood flow, and antioxidants increase NO bioavailability. What remains unknown is whether antioxidants can increase umbilical blood flow. Melatonin participates in circadian, seasonal, and reproductive physiology, but has also been reported to act as a potent endogenous antioxidant. We tested the hypothesis that treatment during pregnancy with melatonin increases umbilical blood flow via NO‐dependent mechanisms. This was tested in pregnant sheep by investigating in vivo the effects on continuous measurement of umbilical blood flow of melatonin before and after NO blockade with a NO clamp. These effects of melatonin were compared with those of the traditional antioxidant, vitamin C. Under anesthesia, 12 pregnant sheep and their fetuses (0.8 of gestation) were fitted with catheters and a Transonic probe around an umbilical artery, inside the fetal abdomen. Following 5 days of recovery, cardiovascular variables were recorded during fetal i.v. treatment with either melatonin (n = 6, 0.5 ± 0.1 μg/kg/min) or vitamin C (n = 6, 8.9 ± 0.4 mg/kg/min) before and after fetal NO blockade with the NO clamp. Fetal treatment with melatonin or vitamin C increased umbilical blood flow, independent of changes in fetal arterial blood pressure. Fetal NO blockade prevented the increase in umbilical blood flow induced by melatonin or vitamin C. Antioxidant treatment could be a useful clinical tool to increase or maintain umbilical blood flow in complicated pregnancy.
PLUNC protein expression in major salivary glands of HIV‐infected patients
Authors: da Silva AA , Bingle L , Speight PM , Bingle CD , Mauad T , da Silva LFF , Vargas PA
Published: September 2010

Oral Diseases (2011) 17, 258–264

Objective:  To analyse and compare the expression of Palate, Lung, and Nasal Epithelium Clone (PLUNC) proteins in salivary glands from patients with and without AIDS (control group) using autopsy material.

Methods:  We analysed the expression of PLUNCs using immunohistochemistry in parotid (n = 45), submandibular (n = 47) and sublingual gland (n = 37) samples of AIDS patients [30 with normal histology, 21 with mycobacteriosis, 14 with cytomegalovirus (CMV) infection, 30 with chronic non‐specific sialadenitis, and 30 HIV‐negative controls. In situ hybridization (ISH) for SPLUNC 2 in the HIV‐negative group was performed.

Results:  SPLUNC 1 expression was detected in the mucous acini of submandibular and sublingual glands, and SPLUNC 2 were seen in the serous cells. LPLUNC 1 expression was only positive in the salivary ducts. There was a higher expression of SPLUNC 2 in AIDS patients with CMV infection and mycobacteriosis when compared with all other groups. The intensity of staining for SPLUNC 2 was greater around the lesions than the peripheral ones. ISH for SPLUNC 2 showed perinuclear positivity in the serous cells in all HIV‐negative cases.

Conclusions:  SPLUNC 1 and LPLUNC 1 proteins were similarly expressed in the salivary glands of AIDS patients and non‐HIV patients. CMV infection and mycobacteriosis increase SPLUNC 2 expression in serous cells in the salivary gland of AIDS patients.
In vivo effects of zoledronic acid on oral mucosal epithelial cells
Authors: Allam E , Allen MR , Chu T‐M , Ghoneima A , Jack Windsor L
Published: September 2010

Oral Diseases (2011) 17, 291–297

Objective:  Osteonecrosis of the jaw is a serious complication of bisphosphonate treatment for which the pathophysiology is unknown. The purpose of this study was to investigate whether in vivo zoledronic acid (ZA) induces alterations in cell proliferation, apoptosis, and matrix metalloproteinases (MMPs) expression in oral mucosal epithelial cells.

Methods:  One‐year‐old dogs were either untreated (control group) or given high doses of intravenous ZA (ZA group) for 3 months. The doses of ZA were equivalent to those given to cancer patients, yet were administered two times more frequently (every 2 weeks). Mucosal tissues were assessed immunohistochemically for cell proliferation (proliferating cell nuclear antigen, PCNA), matrix metalloproteinase (MMP) expression, and apoptosis (caspase 3 and TUNEL).

Results:  There were no significant differences between the groups with respect to PCNA, MMP‐2, MMP‐14, and TUNEL positive cells. However, the expression of MMP‐9 was significantly higher in the control group than in the ZA group (P < 0.05), whereas the expression of caspase 3 was significantly lower in the control group than in the ZA group (P < 0.05).

Conclusion:  These results suggest that high doses of ZA resulted in higher levels of apoptosis and lower levels of MMP‐9 in the oral epithelial cells supporting the idea of bisphosphonate treatment affects the oral mucosa.
Clinical features of microinvasive stage I oral carcinoma
Authors: Pentenero M , Navone R , Motta F , Marino R , Gassino L , Broccoletti R , Gandolfo S
Published: September 2010

Oral Diseases (2011) 17, 298–303

Background:  This study aimed to analyse a case series of microinvasive (tumour thickness <4 mm) stage I oral squamous cell carcinoma (OSCC), with an emphasis on the clinical features of the tumours.

Methods:  In total, 32 microinvasive and 67 non‐microinvasive stage I lesions, which had been surgically treated, were retrospectively studied and compared. The data analysed included gender, age, risk habits, clinical appearance, lesion site, symptoms, nodal involvement and outcome.

Results:  The clinical features of microinvasive lesions meant that, more often than not, they resembled premalignant lesions (P = 0.008), and diagnosis was mainly based on accurate clinical examination rather than the presence of symptoms (P = 0.029). During a median follow‐up of 4.5 years, one nodal involvement and one cancer‐related death were observed in patients with microinvasive lesions. A significantly higher (P = 0.044) level of nodal involvement was observed in the non‐microinvasive lesion group.

Conclusions:  Stage I OSCC has a favourable prognosis overall, but nodal recurrence is more common in non‐microinvasive cancers. As microinvasive lesions tend to present clinically as premalignant lesions, accurate clinical examination is essential if misdiagnosis of early lesions is to be avoided.
Temporary loss of plasma membrane integrity in orthodontic tooth movement
Authors: Orellana‐Lezcano MF , Major PW , McNeil PL , Borke JL
Published: September 2010

Authors –  Orellana‐Lezcano MF, Major PW, McNeil PL, Borke JL

In these studies, a rat model of orthodontic tooth movement was used to support the premise that periodontal ligament (PDL) cells experience plasma membrane disruption and resealing events upon application of mechanical stress. Immunoelectron microscopy, showed albumin in the cytoplasm of PDL and bone lining cells in the tension side of moved molars. The intracellular localization of this large molecule (60 KDa) suggests that these cells have undergone plasma membrane disruption and resealing. To further assess these and previous findings, fluorescent dyes (FITC‐dextran and rhodamine‐dextran) were delivered into the vascular system followed by application of 50 g of static load. These large dextran molecules (10 KDa) were preferentially taken up by PDL cells of the buccal (tension side) of moved molars. These cells were determined to be viable since dead cells do not retain these diffusible tracers. These studies provide evidence of a novel cellular mechanism for uptake and release of molecules and suggest a potential role for plasma membrane disruption in the mechanotransduction of orthodontic tooth movement.
Tolerance of deviations in eye and mouth position
Authors: Evans CA , Viana G , Anderson NK , Giddon DB
Published: September 2010

Structured Abstract

Authors –  Evans CA, Viana G, Anderson NK, Giddon DB

Objective –  To develop and refine a technique for measuring the tolerance for deviations in facial appearance.

Design –  A psychophysical method was administered using photocopies of altered facial photographs to measure tolerances for deviations in eye position and mouth angulation and judges’ reaction time.

Methods –  Stimulus photos were displayed as Kodachrome slides to 76 individuals grouped by their familiarity with craniofacial anomalies, i.e. dental professionals, orthodontic and craniofacial patients, also a group of normal patients.

Results –  (1) Tolerance for deviation of facial appearance varies inversely with the magnitude of the physical deviations from normal; (2) tolerance varies directly as a function of assumed familiarity with deviation; (3) response and reaction time varied inversely with the tolerance for facial deviation.

Conclusion –  Significant differences in tolerance and reaction time were found among the groups and depended on whether an isolated feature was judged or if the feature was judged in the context of the whole face.