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The COVID-19 pandemic has brought sweeping changes to global tourism alongside large-scale travel restrictions, posing complex challenges to entrepreneurs and firms seeking to find their footing in a turbulent climate. This study presents a theoretical framework linking uncertainty, capital, and innovation to analyse how bed-and-breakfast small and medium-sized enterprises have innovatively responded to unprecedented obstacles during COVID-19 recovery. Three-stage longitudinal interviews were conducted with more than 30 entrepreneurs between April and November 2020 to unpack their ongoing responses to the pandemic. The recovery process was found to be non-linear due to the shifting nature of sources of uncertainty and changes in entrepreneurs' capital. These alterations shaped interviewees' responses, especially in terms of product and marketing innovations, which ultimately generated new uncertainty.
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BACKGROUND: A vermiculite processing plant in a Minneapolis, Minnesota neighborhood utilized asbestos-containing ore from Libby, Montana from the late 1930's until 1989. Multiple pathways of exposure to Libby asbestos were characterized in a cohort of over 6000 plant workers and residents living near the plant. OBJECTIVE: We conducted a cohort linkage study to assess the impact of cumulative low dose exposure and the role of occupational history on asbestos-related mortality and cancer morbidity among cohort members residing near a vermiculite plant. METHODS: Cohort members alive in 1988 (nâ¯=â¯5848) were linked to the Minnesota Cancer Surveillance System to identify incident cases of mesothelioma, lung cancer, and all-cancer diagnosed from 1988 to 2010. Proportional incidence ratios (PIRs) were calculated for mesothelioma and lung cancer. Vital status and cause of death were ascertained from Minnesota vital records and the National Death Index (1988-2011). Mortality rates of the cohort (2001-2011) for asbestos-related outcomes were compared to the Minnesota population to estimate standardized mortality ratios (SMRs) and stratified by gender, exposure, and occupational history categories. RESULTS: We identified seven cases of mesothelioma, with elevated incidence only in females (PIRâ¯=â¯11.76, 95% CI: 3.17, 30.12). Lung cancer was elevated in both genders: PIRâ¯=â¯1.54 (95% CI: 1.19, 2.0) in males and 1.62 (95% CI: 1.21, 2.12) in females. We found elevated mortality from COPD, lung cancer, and mesothelioma among females (SMR for mesothelioma in femalesâ¯=â¯18.97, CI: 3.91, 55.45), among the 546 deaths identified. All four deaths from mesothelioma occurred in the >75th percentile of exposure (>0.0156 fiber/cc x months). The SMR for lung cancer and all respiratory cancer was elevated even after controlling for occupation. CONCLUSIONS: Community exposure to Libby amphibole asbestos from a vermiculite processing plant is associated with increased risk of COPD, lung cancer and mesothelioma incidence and mortality, most notably among females, and is likely to remain a public health issue for years to come.
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Silicatos de Aluminio , Amianto , Neoplasias Pulmonares/epidemiología , Mesotelioma/epidemiología , Exposición Profesional/estadística & datos numéricos , Asbestos Anfíboles , Femenino , Humanos , Incidencia , Masculino , Minnesota/epidemiología , MontanaRESUMEN
Cosmetologists face a variety of occupational health and safety challenges. To gather information on respiratory issues related to work as a cosmetologist, licensed cosmetologists were invited by e-mail to participate in a short online survey. The survey collected demographic data, work history, respiratory symptoms, product usage, and health and safety training. Results revealed that while 57% of cosmetologists reported having received training on customer or consumer safety, only 10.5% had received training on worker health such as work-related asthma and/or breathing issues. Respiratory symptoms were reported by 46% of respondents. Length of employment and the use of glues or adhesives were associated with a diagnosis of asthma.
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Industria de la Belleza , Cosméticos/efectos adversos , Educación en Salud , Exposición Profesional/estadística & datos numéricos , Enfermedades Respiratorias/epidemiología , Adolescente , Adulto , Anciano , Asma/inducido químicamente , Asma/epidemiología , Asma/prevención & control , Femenino , Educación en Salud/estadística & datos numéricos , Humanos , Masculino , Persona de Mediana Edad , Minnesota , Exposición Profesional/efectos adversos , Exposición Profesional/prevención & control , Enfermedades Respiratorias/inducido químicamente , Encuestas y Cuestionarios , Adulto JovenRESUMEN
Fatal crash risk is higher at night for all drivers, but especially for young, inexperienced drivers (1). To help address the increased crash risk for beginner teen drivers, 49 states and the District of Columbia include a night driving restriction (NDR) in their Graduated Driver Licensing (GDL) system. NDRs have been shown to reduce crashes among newly licensed teens, with higher reductions associated with NDRs starting at 10:00 p.m. or earlier (2-3). However, in 23 states and the District of Columbia, NDRs begin at 12:00 a.m. or later, times when most teen drivers subject to GDL are not driving. CDC analyzed 2009-2014 national and state-level data from the Fatality Analysis Reporting System (FARS) to determine the proportion of drivers aged 16 or 17 years involved in fatal crashes who crashed at night (9:00 p.m.-5:59 a.m.) and the proportion of these drivers who crashed before 12:00 a.m. Nationwide, among 6,104 drivers aged 16 or 17 years involved in fatal crashes during 2009-2014, 1,865 (31%) were involved in night crashes. Among drivers involved in night crashes, 1,054 (57%) crashed before 12:00 a.m. State-level analyses revealed an approximately twofold variation among states in both the proportions of drivers aged 16 or 17 years involved in fatal crashes that occurred at night and the proportions of night fatal crash involvements that occurred before 12:00 a.m. Because nearly all of the night driving trips taken by drivers aged 16 or 17 years end before 12:00 a.m., NDRs beginning at 12:00 a.m. or later provide minimal protection. States could consider updating their NDR coverage to include earlier nighttime hours. This descriptive report summarizes the characteristics of NDRs, estimates the extent to which drivers aged 16 or 17 years drive at night, and describes their involvement in fatal nighttime crashes during 2009-2014. The effects of NDRs on crashes were not evaluated because of the small state-level sample sizes during the 6-year study period.
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Accidentes de Tránsito/mortalidad , Conducción de Automóvil/legislación & jurisprudencia , Concesión de Licencias/legislación & jurisprudencia , Adolescente , Humanos , Factores de Tiempo , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: The Rochester Epidemiology Project (REP) is a unique community-based medical record data linkage system that provides individual patient address, diagnosis and visit information for all hospitalizations, as well as emergency department, urgent care and outpatient clinic visits for asthma. Proximity to traffic is known to be associated with asthma exacerbations and severity. Our null hypothesis was that there is no association between residential proximity to traffic and asthma exacerbations over eleven years of REP data. METHODS: Spatial coordinates of the homes of 19,915 individuals diagnosed with asthma were extracted from the REP database. Three metrics of traffic exposure at residences were calculated from link-based traffic count data. We used exploratory statistics as well as logistic and Poisson regression to examine associations between three traffic metrics at the home address and asthma exacerbations. RESULTS: Asthma exacerbations increased as traffic levels near the home increased. Proximity to traffic was a significant predictor of asthma exacerbations in logistic and Poisson regressions controlling for age, gender and block group poverty. CONCLUSIONS: Over eleven years in a comprehensive county-wide data set of asthma patients, and after controlling for demographic effects, we found evidence that living in proximity to traffic increased the risk of asthma exacerbations.
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Asma/epidemiología , Emisiones de Vehículos , Adolescente , Adulto , Anciano , Niño , Preescolar , Bases de Datos Factuales , Exposición a Riesgos Ambientales , Femenino , Vivienda , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Minnesota/epidemiología , Análisis de Regresión , Adulto JovenRESUMEN
Lead exposure is associated with a number of adverse health events including peripheral neuropathy, anemia, renal damage and cognitive impairment. The vast majority of adult lead exposures occur in the workplace. By statute, all results from blood lead level (BLL) tests performed in Minnesota are submitted to the Minnesota Department of Health for surveillance purposes. We analyzed that data to examine lead exposure trends from 2005 through 2012. We found that an average of 548 persons 16 years of age and older had a BLL greater than 10 µg/dL each year during that period. Analysis of the prevalence rate of elevated BLLs among adults for the years 2005-2012 showed a modest, nonsignificant decline among those with BLLs greater than 1O µg/dL. Much has been done to reduce exposures and BLLs among young children. However, the policies and standards that protect workers have not been similarly adjusted, and many workers remain at risk of exposure. Although OSHA is responsible for developing and implementing policies and standards to protect workers, health care providers can play a critical role in identifying cases of lead exposure by asking patients about their occupation and industry. Those working in high-risk industries should be tested to determine whether they have been exposed and intervention is warranted.
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Política de Salud/tendencias , Intoxicación por Plomo/sangre , Intoxicación por Plomo/epidemiología , Plomo/sangre , Vigilancia de la Población , Adulto , Niño , Preescolar , Estudios Transversales , Predicción , Humanos , Lactante , Intoxicación por Plomo/prevención & control , Minnesota , Valores de ReferenciaRESUMEN
During 2004-2013, the number of passenger vehicle drivers aged 16-19 years involved in fatal crashes in the United States declined by 55% from 5,724 to 2,568.* In addition to graduated driver licensing (GDL) programs and safer vehicles, other possible contributors to the decline include adolescents waiting longer to get their driver licenses and driving less. The crash risk for drivers of any age is highest during the first months of independent driving, and this risk is highest for the youngest teenage drivers. To estimate the percentage of high school students aged ≥16 years who have driven during the past 30 days, by age, race/ethnicity, and location, CDC analyzed 2013 data from the national Youth Risk Behavior Survey (YRBS) and YRBS data collected by 42 states and 21 large urban school districts. Nationwide, 76.3% of high school students aged ≥16 years reported having driven during the 30 days before the survey; 83.2% of white students had driven compared with <70% of black and Hispanic students. Across 42 states, the percentage of students who drove ranged from 53.8% to 90.2%. Driving prevalence was higher in the midwestern and mountain states. Across the 21 large urban school districts, the percentage of drivers varied more than twofold from 30.2% to 76.0%. This report provides the most detailed evidence to date that the percentage of students who drive varies substantially depending on where they live. Such information will be vital as states and communities consider potential ways to improve safety for older teenage novice drivers and plan for safe, affordable transportation options for those who do not drive.
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Conducción de Automóvil/estadística & datos numéricos , Estudiantes , Adolescente , Negro o Afroamericano/estadística & datos numéricos , Femenino , Hispánicos o Latinos/estadística & datos numéricos , Humanos , Masculino , Instituciones Académicas , Estudiantes/estadística & datos numéricos , Estados Unidos , Población Blanca/estadística & datos numéricos , Adulto JovenRESUMEN
Perfluorochemicals (PFCs) are pervasive and persistent environmental contaminants with uncertain public health implications. Following the discovery of PFC contamination in public and private drinking water supplies in Washington County, Minnesota, the authors conducted a pilot biomonitoring study. Serum samples from 196 residents of two communities were analyzed for seven PFCs. Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexanesulfonate (PFHxS) were detected in all serum samples collected. Perfluorobutanoic acid (PFBA) and perfluorobutane sulfonate (PFBS) were found in 28% and 3% of the samples, respectively. The geometric mean for PFOA was 15.4 ng/mL (range: 1.6-177 ng/mL), PFOS was 35.9 ng/mL (range: 3.2-448 ng/mL), and PFHxS was 8.4 ng/mL (range 0.32-316 ng/mL). Mean levels for PFOA, PFOS, and PFHxS were higher in males and increased with age. Mean PFC serum levels for three PFCs were significantly elevated when compared to levels found in the U.S. population.
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Agua Potable/análisis , Exposición a Riesgos Ambientales , Fluorocarburos/sangre , Contaminantes Químicos del Agua/sangre , Adulto , Anciano , Anciano de 80 o más Años , Monitoreo del Ambiente , Femenino , Humanos , Masculino , Persona de Mediana Edad , Minnesota , Proyectos Piloto , Adulto JovenRESUMEN
BACKGROUND: The study of the geographical distribution of disease has expanded greatly with GIS technology and its application to increasingly available public health data. The emergence of this technology has increased the challenges for public health practitioners to provide meaningful interpretations for county-based state cancer maps. METHODS: One of these challenges-spurious inferences about the significance of differences between county and overall state cancer rates-can be addressed through a nonparametric statistical method. The Wilcoxon's signed rank test (WSRT) has a practical application for determining the significance of county cancer rates compared to the statewide rate. This extension of the WSRT, developed by John Tukey, forms the basis for constructing a single confidence interval for all differences in county and state directly age-adjusted cancer rates. Empirical evaluation of this WSRT application was conducted using Minnesota cancer incidence data. RESULTS: The WSRT procedure reduced the impact of statistical artifacts that are frequently encountered with standard normal significance testing of the difference between directly age-adjusted county and the overall state cancer rates. CONCLUSION: Although further assessment of its performance is required, the WSRT procedure appears to be a useful complement for mapping directly age-adjusted state cancer rates by county.
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Neoplasias/epidemiología , Adolescente , Niño , Preescolar , Intervalos de Confianza , Femenino , Sistemas de Información Geográfica , Geografía , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Minnesota/epidemiología , Salud Pública/métodos , Estadísticas no ParamétricasRESUMEN
Plastics, "yesterday's hero... today's villain" or "the contemporary symbol of modernity," were invented in the early 20th century by Leo Hendrik Baekeland from macromolecules (resins, elastomers, and artificial fibres) of formaldehyde and phenol. This synthetic organic polymer took hold of daily human life and transformed the modern world with an ever-widening range of applications. Plastics are the third most-widely manufactured material in the world after cement and steel, and they have become widespread in our society with excessive production and consumption to meet demand. Plastics use is so dominant that they are inappropriately considered essential in the world consumers marketplace. Plastics are a clear indicator of the Anthropocene and can be considered the marker of the upper subdivision of this stage: the Plasticene.
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Gastrópodos , Plásticos , Humanos , Animales , Polímeros , Formaldehído , FenolRESUMEN
Plastic production is an essential part of the world economy that has mushroomed exponentially with c.9.2 billion tonnes estimated to have been made between 1950 and 2017. Now, each year c.8-11 million tonnes of plastic waste escapes into the oceans. Plastic usage is varied but the packaging industry accounts for 47%. Recycling and the circular economy are seen as keys to unlocking the plastic problem, for example, via the Extended Producer Responsibility scheme; a Deposit Return Scheme. The circular economy is a fine idea and has been around a long time, but has it made any real difference? The amount of plastic in circulation keeps getting bigger and bigger. More thought must be given to creating technologies and designs that can deal with waste management, integrate international collaboration and cut waste to a bare minimum at its source point upstream. No single solution exists, but there is a need for a legally binding global governance arrangement that would effectively and measurably limit and control plastic pollution. Many governments are in favour of this.
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Plásticos , Administración de Residuos , Contaminación Ambiental , Embalaje de Productos , ReciclajeRESUMEN
This study analyses how Covid-19 shapes individuals' international tourism intentions in context of bounded rationality. It provides a novel analysis of risk which is disaggregated into tolerance/aversion of and competence to manage risks across three different aspects: general, domain (tourism) and situational (Covid-19). The impacts of risk are also differentiated from uncertainty and ambiguity. The empirical study is based on large samples (total = 8962) collected from the world's top five tourism source markets: China, USA, Germany, UK and France. Various risk factors show significant predictive powers of individual's intentions to defer international tourism plans amid Covid-19. Uncertainty and ambiguity intolerance is shown to lead to intentions to take holidays relatively sooner rather than delaying the holiday plans.
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Litter is one of the most pervasive and fastest-growing anthropogenic alterations of the World's coasts and oceans. Along with climate change, litter has been identified as one of humankind's most critical environmental problems that demand urgent solutions. Litter magnitudes and distribution, and the related detrimental environmental effects, have been documented in all existing coastal and marine environments (e.g., beaches, dunes, abyssal plains and submarine canyons, among others). Litter's presence is now so ubiquitous in the environment that it serves as a geological indicator of the Anthropocene. As part of the solution to this out-of-hand problem, Marine Pollution Bulletin has produced this Special Issue entitled "Litter in Coastal and Marine Environments". This collection of 37 papers provides a focal point for such related current studies and, in part, seeks to discuss implementing specific management strategies under different scenarios. No single solution exists to cope with the litter issue. However, legally binding global governance that will effectively limit and control the magnitude of litter pollution is greatly needed. The topical range of this collection of papers includes case studies focussing on litter types (mainly dominated by plastics), sources, impacts and solutions.
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Monitoreo del Ambiente , Residuos , Contaminación Ambiental , Océanos y Mares , Plásticos , Residuos/análisisRESUMEN
The islands of the South Pacific contribute a fraction of the mis-managed plastics in the world's ocean, yet the region is one of the main recipients of its impacts. Based on expert interviews and a review of current strategies to prevent marine plastic pollution in six countries (Australia, New Zealand, Fiji, Tonga, Vanuatu, United Kingdom), this paper identifies several interventions - legislative, financial, voluntary - which governments, organisations and individuals can learn from. Both voluntary and statutory consumer-based behaviour change campaigns are well developed and somewhat successful in several countries. While sub-national policies do not inhibit progress, they are not optimal. Harmonisation across the territories of federal and devolved systems is beneficial, such as container return schemes, levies, and bans. Vanuatu has displayed high ambition, and the challenges in achieving this serve as a case study. A coordinated global strategy with associated legislation aimed at tackling plastic pollution is critical.
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Contaminación Ambiental , Plásticos , Monitoreo del Ambiente , Contaminación Ambiental/prevención & control , Fiji , Humanos , Océanos y Mares , Océano Pacífico , Reino Unido , Residuos/análisisRESUMEN
The growing literature on microplastics (MPs) in coastal and marine environs reflects the seriousness of this pollutant category. Diverse litter studies on Colombia's Central Caribbean Coast have not presented detailed study of MPs' typology, magnitude or distribution. This baseline study presents for first time the MPs problem on 23 beaches in 75 km coastal reach between Punta Roca and Galerazamba, on the central Colombian Caribbean Coast. The Microplastics Pollution Index (MPPI) and Coefficient of Microplastic Impact (CMPI) were developed and applied along with the Environmental Status Index (ESI) and their integration through sector analysis, and mapping using Agglomerative Hierarchical Clustering and Multidimensional Scaling, and Principal Components Analysis. Microplastics abundances (densities) ranged from 2457 to 557 MPs/kg, similar to other global beaches and bays. The MPs Index for the 23 beaches classified 8 beaches as "Moderate," 10 beaches as "High" and 5 as "Very High." Microplastic fibers were the dominant typology at 83% of the combined beaches total (ranging from Moderate to Very High for individual beaches).
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Microplásticos , Contaminantes Químicos del Agua , Playas , Región del Caribe , Colombia , Monitoreo del Ambiente , Plásticos , Contaminantes Químicos del Agua/análisisRESUMEN
Along 24 beaches of the Central Caribbean Coast of Colombia, plastic items were collected and grouped into 43 different typologies. The average plastic abundance was 4.54 items/m2 being eight typologies responsible for 82% of all plastic collected. The application of the Clean Coast Index (CCI) and the Plastic Abundance Index (PAI) allows categorization of the study area as "Extremely Dirty" coastal strip with a "Very High Abundance" of plastics. Beaches were statistically grouped into three specific types: moderate, bad and extremely bad environmental conditions. The typology and magnitudes of plastics found in the study area suggest a combination of sources that primarily include dumping and direct activities on the beach. Plastic medical and sanitary waste, ocean/waterway items, and plastic items related to smoking-related activities also were observed.
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Playas , Plásticos , Región del Caribe , Colombia , Monitoreo del Ambiente , Residuos/análisisRESUMEN
By proposing TSH as a key negative regulator of bone turnover, recent studies in TSH receptor (TSHR) null mice challenged the established view that skeletal responses to disruption of the hypothalamic-pituitary-thyroid axis result from altered thyroid hormone (T(3)) action in bone. Importantly, this hypothesis does not explain the increased risk of osteoporosis in Graves' disease patients, in which circulating TSHR-stimulating antibodies are pathognomonic. To determine the relative importance of T(3) and TSH in bone, we compared the skeletal phenotypes of two mouse models of congenital hypothyroidism in which the normal reciprocal relationship between thyroid hormones and TSH was intact or disrupted. Pax8 null (Pax8(-/-)) mice have a 1900-fold increase in TSH and a normal TSHR, whereas hyt/hyt mice have a 2300-fold elevation of TSH but a nonfunctional TSHR. We reasoned these mice must display opposing skeletal phenotypes if TSH has a major role in bone, whereas they would be similar if thyroid hormone actions predominate. Pax8(-/-) and hyt/hyt mice both displayed delayed ossification, reduced cortical bone, a trabecular bone remodeling defect, and reduced bone mineralization, thus indicating that the skeletal abnormalities of congenital hypothyroidism are independent of TSH. Treatment of primary osteoblasts and osteoclasts with TSH or a TSHR-stimulating antibody failed to induce a cAMP response. Furthermore, TSH did not affect the differentiation or function of osteoblasts or osteoclasts in vitro. These data indicate the hypothalamic-pituitary-thyroid axis regulates skeletal development via the actions of T(3).
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Desarrollo Óseo/fisiología , Hipotiroidismo/patología , Factores de Transcripción Paired Box/fisiología , Hormonas Tiroideas/sangre , Tirotropina/sangre , Animales , Western Blotting , Desarrollo Óseo/efectos de los fármacos , Desarrollo Óseo/genética , Remodelación Ósea/efectos de los fármacos , Remodelación Ósea/genética , Remodelación Ósea/fisiología , Huesos/anomalías , Huesos/metabolismo , Calcificación Fisiológica/efectos de los fármacos , Calcificación Fisiológica/genética , Calcificación Fisiológica/fisiología , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Diferenciación Celular/fisiología , Células Cultivadas , AMP Cíclico/metabolismo , Hipotiroidismo/sangre , Hipotiroidismo/genética , Hibridación in Situ , Ratones , Ratones Noqueados , Osteoblastos/citología , Osteoblastos/efectos de los fármacos , Osteoblastos/metabolismo , Osteoclastos/citología , Osteoclastos/efectos de los fármacos , Osteoclastos/metabolismo , Osteogénesis/efectos de los fármacos , Osteogénesis/fisiología , Factor de Transcripción PAX8 , Factores de Transcripción Paired Box/genética , Factores de Transcripción Paired Box/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Glándula Tiroides/metabolismo , Hormonas Tiroideas/farmacologíaRESUMEN
Euthyroid status is essential for normal skeletal development and maintenance of the adult skeleton, but the mechanisms which control supply of thyroid hormone to bone cells are poorly understood. Thyroid hormones enter target cells via monocarboxylate transporter-8 (MCT8), which provides a functional link between thyroid hormone uptake and metabolism in the regulation of T3-action but has not been investigated in bone. Most circulating active thyroid hormone (T3) is derived from outer ring deiodination of thyroxine (T4) mediated by the type 1 deiodinase enzyme (D1). The D2 isozyme regulates intra-cellular T3 supply and determines saturation of the nuclear T3-receptor (TR), whereas a third enzyme (D3) inactivates T4 and T3 to prevent hormone availability and reduce TR-saturation. The aim of this study was to determine whether MCT8 is expressed in the skeleton and whether chondrocytes, osteoblasts and osteoclasts express functional deiodinases. Gene expression was analyzed by RT-PCR and D1, D2 and D3 function by sensitive and highly specific determination of enzyme activities. MCT8 mRNA was expressed in chondrocytes, osteoblasts and osteoclasts at all stages of cell differentiation. D1 activity was undetectable in all cell types, D2 activity was only present in mature osteoblasts whereas D3 activity was evident throughout chondrocyte, osteoblast and osteoclast differentiation in primary cell cultures. These data suggest that T3 availability especially during skeletal development may be limited by D3-mediated catabolism rather than by MCT8 mediated cellular uptake or D2-dependent T3 production.
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Huesos/enzimología , Yoduro Peroxidasa/metabolismo , Animales , Femenino , Yoduro Peroxidasa/genética , Masculino , Ratones , Ratones Endogámicos , Ratas , Ratas Endogámicas , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Rhizobium leguminosarum bv. viciae 3841 contains six putative quaternary ammonium transporters (Qat), of the ABC family. Qat6 was strongly induced by hyperosmosis although the solute transported was not identified. All six systems were induced by the quaternary amines choline and glycine betaine. It was confirmed by microarray analysis of the genome that pRL100079-83 (qat6) is the most strongly upregulated transport system under osmotic stress, although other transporters and 104 genes are more than threefold upregulated. A range of quaternary ammonium compounds were tested but all failed to improve growth of strain 3841 under hyperosmotic stress. One Qat system (gbcXWV) was induced 20-fold by glycine betaine and choline and a Tn5::gbcW mutant was severely impaired for both transport and growth on these compounds, demonstrating that it is the principal system for their use as carbon and nitrogen sources. It transports glycine betaine and choline with a high affinity (apparent K(m), 168 and 294 nM, respectively).
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Transportadoras de Casetes de Unión a ATP/metabolismo , Proteínas Bacterianas/metabolismo , Compuestos de Amonio Cuaternario/metabolismo , Rhizobium leguminosarum/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Proteínas Bacterianas/genética , Transporte Biológico , Regulación Bacteriana de la Expresión Génica , Mutación , Operón , Pisum sativum/crecimiento & desarrollo , Pisum sativum/microbiología , Rhizobium leguminosarum/genéticaRESUMEN
Although graduated driver licensing has successfully reduced the young driver problem in Canada and the U.S., this is still a major problem and more needs to be done. This article discusses what new measures are needed to further reduce the problem. To make graduated licensing work better, laws need strengthening; compliance needs to be enhanced through evidence-based programs involving parents, police, and adolescents; and consideration needs to be given to strengthening testing requirements. A major challenge is to integrate driver education with graduated licensing, and suggestions for doing so are provided here. There are many opportunities for building on the initial gains derived from present-day graduated systems. Taking advantage of these opportunities is likely to result in substantial crash reductions.