Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 72
Filtrar
1.
Pancreatology ; 15(4 Suppl): S32-8, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25845856

RESUMO

The abundant stromal/desmoplastic reaction, a characteristic feature of a majority of pancreatic adenocarcinomas (PDAC), has only recently been receiving some attention regarding its possible role in the pathobiology of pancreatic cancer. It is now well established that the cells predominantly responsible for producing the collagenous stroma are pancreatic stellate cells (PSCs). In addition to extracellular matrix proteins, the stroma also exhibits cellular elements including, immune cells, endothelial cells and neural cells. Evidence is accumulating to indicate the presence of significant interactions between PSCs and cancer cells as well as between PSCs and other cell types in the stroma. The majority of research reports to date, using in vitro and in vivo approaches, suggest that these interactions facilitate local growth as well as distant metastasis of pancreatic cancer, although a recent study using animals depleted of myofibroblasts has raised some questions regarding the central role of myofibroblasts in cancer progression. Nonetheless, novel therapeutic strategies have been assessed, mainly in the pre-clinical setting, in a bid to interrupt stromal-tumour interactions and inhibit disease progression. The next important challenge is for the translation of such pre-clinical strategies to the clinical situation so as to improve the outcome of patients with pancreatic cancer.


Assuntos
Neoplasias Pancreáticas/patologia , Microambiente Tumoral , Adenocarcinoma/patologia , Animais , Humanos
2.
Indoor Air ; 23(6): 515-28, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23506393

RESUMO

Limited evidence associates inadequate classroom ventilation rates (VRs) with increased illness absence (IA). We investigated relationships between VRs and IA in California elementary schools over two school years in 162 3rd-5th-grade classrooms in 28 schools in three school districts: South Coast (SC), Bay Area (BA), and Central Valley (CV). We estimated relationships between daily IA and VR (estimated from two year daily real-time carbon dioxide in each classroom) in zero-inflated negative binomial models. We also compared IA benefits and energy costs of increased VRs. All school districts had median VRs below the 7.1 l/s-person California standard. For each additional 1 l/s-person of VR, IA was reduced significantly (p<0.05) in models for combined districts (-1.6%) and for SC (-1.2%), and nonsignificantly for districts providing less data: BA (-1.5%) and CV (-1.0%). Assuming associations were causal and generalizable, increasing classroom VRs from the California average (4 l/s-person) to the State standard would decrease IA by 3.4%, increase attendance-linked funding to schools by $33 million annually, and increase costs by only $4 million. Further increasing VRs would provide additional benefits. These findings, while requiring confirmation, suggest that increasing classroom VRs above the State standard would substantially decrease illness absence and produce economic benefits.


Assuntos
Infecções Respiratórias/epidemiologia , Instituições Acadêmicas/estatística & dados numéricos , Ventilação , California , Criança , Análise Custo-Benefício , Humanos , Modelos Estatísticos , Estudos Prospectivos , Infecções Respiratórias/prevenção & controle , Instituições Acadêmicas/economia
3.
Indoor Air ; 22(4): 309-20, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22257121

RESUMO

UNLABELLED: This field study of 37 small and medium commercial buildings throughout California obtained information on ventilation rate, temperature, and heating, ventilating, and air-conditioning (HVAC) system characteristics. The study included seven retail establishments; five restaurants; eight offices; two each of gas stations, hair salons, healthcare facilities, grocery stores, dental offices, and fitness centers; and five other buildings. Fourteen (38%) of the buildings either could not or did not provide outdoor air through the HVAC system. The air exchange rate averaged 1.6 (s.d. = 1.7) exchanges per hour and was similar between buildings with and without outdoor air supplied through the HVAC system, indicating that some buildings have significant leakage or ventilation through open windows and doors. Not all buildings had sufficient air exchange to meet ASHRAE 62.1 Standards, including buildings used for fitness centers, hair salons, offices, and retail establishments. The majority of the time, buildings were within the ASHRAE temperature comfort range. Offices were frequently overcooled in the summer. All of the buildings had filters, but over half the buildings had a filter with a minimum efficiency reporting value rating of 4 or lower, which are not very effective for removing fine particles. PRACTICAL IMPLICATIONS: Most U.S. commercial buildings (96%) are small- to medium-sized, using nearly 18% of the country's energy, and sheltering a large population daily. Little is known about the ventilation systems in these buildings. This study found a wide variety of ventilation conditions, with many buildings failing to meet relevant ventilation standards. Regulators may want to consider implementing more complete building inspections at commissioning and point of sale.


Assuntos
Filtros de Ar , Poluição do Ar em Ambientes Fechados , Planejamento Ambiental , Saúde Ambiental/métodos , Temperatura , Ventilação , California , Exposição Ambiental/efeitos adversos , Humanos , Síndrome do Edifício Doente/epidemiologia , Estatística como Assunto
4.
Indoor Air ; 22(3): 224-34, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22044446

RESUMO

UNLABELLED: The performance metrics of airflow, sound, and combustion product capture efficiency (CE) were measured for a convenience sample of 15 cooking exhaust devices, as installed in residences. Results were analyzed to quantify the impact of various device- and installation-dependent parameters on CE. Measured maximum airflows were 70% or lower than values noted on product literature for 10 of the devices. Above-the-cooktop devices with flat-bottom surfaces (no capture hood)--including exhaust fan/microwave combination appliances--were found to have much lower CE at similar flow rates, compared to devices with capture hoods. For almost all exhaust devices and especially for rear-mounted downdraft exhaust and microwaves, CE was substantially higher for back compared with front burner use. Flow rate, and the extent to which the exhaust device extends over the burners that are in use, also had a large effect on CE. A flow rate of 95 liters per second (200 cubic feet per minute) was necessary, but not sufficient, to attain capture efficiency in excess of 75% for the front burners. A-weighted sound levels in kitchens exceeded 56 dB* when operating at the highest fan setting for all 14 devices evaluated for sound performance. PRACTICAL IMPLICATIONS: Natural gas cooking burners and many cooking activities emit pollutants that can reach hazardous levels in homes. Venting range hoods and other cooking exhaust fans are thought to provide adequate protection when used. This study demonstrates that airflows of installed devices are often below advertised values and that less than half of the pollutants emitted by gas cooking burners are removed during many operational conditions. For many devices, achieving capture efficiencies that approach or exceed 75% requires operation at settings that produce prohibitive noise levels. While users can improve performance by preferentially using back burners, results suggest the need for improvements in hood designs to achieve high pollutant capture efficiencies at acceptable noise levels.


Assuntos
Culinária , Ventilação/instrumentação , Humanos , Análise de Regressão , Ventilação/normas
5.
Radiats Biol Radioecol ; 49(3): 372-82, 2009.
Artigo em Russo | MEDLINE | ID: mdl-19637748

RESUMO

The study of aerosol exposure, dosimetry measurements and related quantitation of health effects are important to the understanding of the consequences of air pollution, and are discussed widely in the scientific literature. During the last 10 years the need to correlate aerosol exposure and biological effects has become especially important due to rapid development of a new, revolutionary industry of nanotechnology. Quantitative assessment of aerosol particle behavior in air and in lung deposition, and dosimetry in different parts of the lung, particularly for nanoaerosols, remains poor despite several decades of study. Direct measurements on humans are still needed in order to validate the hollow cast, animal studies, and lung deposition modeling. We discuss here the use of nanoscale radon decay products as an experimental tool in the study of local deposition and lung dosimetry for nanoaerosols. The issue of the safe use of radon progeny in such measurements is discussed based on a comparison of measured exposure in 3 settings: general population, miners, and in a human experiment conducted at the Paul Scherer Institute (PSI) in Switzerland. One of the properties of radon progeny is that they consist partly of 1 nm radioactive particles called unattached activity; having extremely small size and high diffusion coefficients, these particles can be potentially useful as radioactive tracers in the study of nanometer-sized aerosols. We present a theoretical and experimental study of the correlation between the unattached activity and aerosol particle surface area, together with a method for measurement of the unattached fraction.


Assuntos
Aerossóis/metabolismo , Poluição do Ar em Ambientes Fechados/efeitos adversos , Pulmão/metabolismo , Nanopartículas/efeitos adversos , Radiometria/métodos , Produtos de Decaimento de Radônio/metabolismo , Aerossóis/efeitos adversos , Humanos , Pulmão/efeitos dos fármacos , Masculino , Nanopartículas/análise , Saúde Ocupacional , Tamanho da Partícula , Produtos de Decaimento de Radônio/efeitos adversos
6.
Ann Rheum Dis ; 67(8): 1170-3, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18299303

RESUMO

OBJECTIVE: To examine the predictors of time to premature gonadal failure (PGF) in patients with systemic lupus erythematosus from LUMINA, a multiethnic US cohort. METHODS: PGF was defined according to the SLICC Damage Index (SDI). Factors associated with time to PGF occurrence were examined by univariable and multivariable Cox proportional hazards regression analyses: three models according to cyclophosphamide use, at T0 (model 1), over time (model 2) and the total number of intravenous pulses (model 3). RESULTS: Thirty-seven of 316 women (11.7%) developed PGF (19 Texan-Hispanics, 14 African-Americans, four Caucasians and no Puerto Rican-Hispanics). By multivariable analyses, older age at T0 (hazards ratio (HR) = 1.10-1.14; 95% CI 1.02-1.05 to 1.19-1.23) and disease activity (Systemic Lupus Activity Measure-Revised) in all models (HR = 1.22-1.24; 95% CI 1.10-1.12 to 1.35-1.37), Texan-Hispanic ethnicity in models 2 and 3 (HR = 4.06-5.07; 95% CI 1.03-1.25 to 15.94-20.47) and cyclophosphamide use in models 1 and 3 (1-6 pulses) (HR = 4.01-4.65; 95% CI 1.55-1.68 to 9.56-13.94) were predictors of a shorter time to PGF. CONCLUSIONS: Disease activity and Texan-Hispanic ethnicity emerged as predictors of a shorter time to PGF while the associations with cyclophosphamide use and older age were confirmed. Furthermore, cyclophosphamide induction therapy emerged as an important determinant of PGF.


Assuntos
Lúpus Eritematoso Sistêmico/imunologia , Menopausa Precoce/imunologia , Doença Aguda , Adulto , Negro ou Afro-Americano , Fatores Etários , Ciclofosfamida/efeitos adversos , Feminino , Hispânico ou Latino , Humanos , Imunossupressores/efeitos adversos , Estudos Longitudinais , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Lúpus Eritematoso Sistêmico/etnologia , Menopausa Precoce/etnologia , Análise Multivariada , Prognóstico , Modelos de Riscos Proporcionais , Risco , População Branca
7.
Ann Rheum Dis ; 67(6): 829-34, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17875548

RESUMO

OBJECTIVE: To examine the predictors of time-to-seizure occurrence and their impact on damage accrual and mortality in LUMINA, a multiethnic (Hispanic, African American and Caucasian) cohort of patients with systemic lupus erythematosus. METHODS: Seizures were defined as per the American College of Rheumatology (ARC) nomenclature and case definitions for neuropsychiatric lupus syndromes. Factors associated with time-to-seizure occurrence occurring at or after diagnosis (TD) of systemic lupus erythematosus were examined by univariable and multivariable Cox proportional hazard regression analyses. The impact of seizures on damage accrual and mortality was also examined by multivariable analyses after adjusting for variables known to affect these outcomes. RESULTS: A total of 600 patients were included in these analyses. Of them, 40 (6.7%) developed seizures at or after TD; by multivariable analyses, disease activity and younger age were independent predictors of a shorter time-to-seizure occurrence (HR = 1.10 and 1.04; 95% CI 1.04 to 1.15 and 1.00 to 1.08, p = 0.0004 and 0.0304, respectively) whereas mucocutaneous involvement (HR = 0.34, 95% CI 0.16 to 0.41, p = 0.0039) and hydroxychloroquine use (HR = 0.35, 95% CI 0.15 to 0.80, p = 0.0131) were independent predictors of a longer time-to-seizure occurrence. Seizures were an independent contributor to damage accrual but not to mortality. CONCLUSIONS: Seizures tend to occur early in the course of systemic lupus erythematosus, and contribute to damage accrual. Younger age and disease activity are independent predictors of a shorter time-to-seizure occurrence; antimalarials appear to have a protective role in seizure occurrence.


Assuntos
Lúpus Eritematoso Sistêmico/etnologia , Convulsões/etnologia , Adulto , Negro ou Afro-Americano , Idade de Início , Progressão da Doença , Feminino , Seguimentos , Indicadores Básicos de Saúde , Hispânico ou Latino , Humanos , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/mortalidade , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Convulsões/etiologia , Convulsões/mortalidade , Fatores Socioeconômicos , População Branca
8.
Rheumatology (Oxford) ; 47(3): 362-7, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18250089

RESUMO

OBJECTIVE: To examine the factors associated with myocarditis and its impact on disease outcomes in SLE patients. METHODS: SLE patients aged > or = 16 yrs, disease duration < or = 5 yrs from LUMINA (LUpus in Minorities: NAture vs nurture), a multiethnic US cohort, were studied. Myocarditis was defined as per the category 3 of the pericarditis/myocarditis item of the SLAM-Revised (SLAM-R). Patients with concurrent pericardial involvement were excluded. Patients with myocarditis were compared with those without myocarditis or its sequelae in the preceding year. The association between myocarditis and baseline variables (T(0)) was first examined. The impact of myocarditis on disease activity over time (SLAM-R), damage accrual [SLICC Damage Index (SDI)] at last visit (T(L)) and mortality was evaluated. RESULTS: Fifty-three of the 496 patients studied had myocarditis. African American ethnicity [Odds ratio (OR) = 12.6; 95% CI 1.6, 97.8] and SLAM-R at diagnosis (OR = 1.1, 95% CI 1.0, 1.1) were significantly and independently associated with myocarditis. Myocarditis did not predict disease activity over time, but approached significance as a predictor of SDI at T(L) in multivariable analyses P = 0.051. Kaplan-Meier curves indicated that myocarditis was associated with shorter survival (log-rank = 4.87, P = 0.02), particularly in patients with > or = 5 yrs disease; however, myocarditis was not retained in the Cox proportional hazards regression model. CONCLUSIONS: Ethnicity and disease activity at diagnosis were associated with the occurrence of myocarditis in SLE. Myocarditis did not significantly impact on disease activity over time, but impacts some on damage accrual and survival, reflecting overall the more severe disease those patients experience.


Assuntos
Etnicidade/estatística & dados numéricos , Lúpus Eritematoso Sistêmico/diagnóstico , Lúpus Eritematoso Sistêmico/epidemiologia , Miocardite/diagnóstico , Miocardite/epidemiologia , Adolescente , Adulto , Negro ou Afro-Americano/etnologia , Distribuição por Idade , Análise de Variância , Estudos de Coortes , Comorbidade , Feminino , Hispânico ou Latino/estatística & dados numéricos , Humanos , Incidência , Modelos Lineares , Estudos Longitudinais , Lúpus Eritematoso Sistêmico/etnologia , Masculino , Pessoa de Meia-Idade , Miocardite/etnologia , Distribuição de Poisson , Prognóstico , Modelos de Riscos Proporcionais , Medição de Risco , Índice de Gravidade de Doença , Distribuição por Sexo , Análise de Sobrevida , População Branca/estatística & dados numéricos
9.
Clin Exp Rheumatol ; 26(2): 268-74, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18565248

RESUMO

OBJECTIVE: To study the factors associated with an adverse pregnancy outcome in women with systemic lupus erythematosus (SLE). METHODS: SLE women from LUMINA of Hispanic, African American and Caucasian ethnicity were studied. Adverse pregnancy outcome was a miscarriage or abortion (<20 weeks), a stillbirth (> or = 20) and/or a moderate to severe preterm-baby (<34 weeks); good outcome was either a mild preterm-baby (> or = 34 weeks) or a full-term baby [C-section or vaginal delivery (38-42 weeks)]. Pregnancies occurring after SLE diagnosis (TD) were included; pregnancy outcome was the unit of analyses. The relationship between selected variables and pregnancy outcomes was examined by univariable and multivariable analyses. RESULTS: Adverse outcomes occurred in 63.7% of 102 pregnancies. In the univariable analyses, Texan Hispanic and African American ethnicities, fewer years of education, higher number of ACR criteria, renal involvement, glucocorticoid exposure and the maximum dose of glucocorticoids used prior to the pregnancy outcome were associated with an adverse pregnancy outcome. Renal involvement was independently associated with an adverse pregnancy outcome [Odds ratio (OR)=5.219 (95% Confidence Interval (CI) 1.416-19.239, p=0.0131] as were the maximum dose of glucocorticoids used prior to the pregnancy outcome (OR=1.028; CI:1.002-1.054; p=0.0315) and fewer years of education (OR=1.204; CI:1.006-1.472; p=0.0437). Ethnicity was not retained in the multivariable model. CONCLUSION: Renal involvement, the maximum dose of glucocorticoids used prior to pregnancy and fewer years of education were associated with adverse pregnancy outcomes. These data have implications for the management of women with lupus planning to become pregnant.


Assuntos
Lúpus Eritematoso Sistêmico/etnologia , Complicações na Gravidez/etnologia , Resultado da Gravidez/etnologia , Aborto Espontâneo/etnologia , Adulto , Negro ou Afro-Americano/estatística & dados numéricos , Estudos de Coortes , Feminino , Glucocorticoides/uso terapêutico , Hispânico ou Latino/estatística & dados numéricos , Humanos , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Gravidez , Nascimento Prematuro/etnologia , Natimorto/etnologia , Estados Unidos/epidemiologia , População Branca/estatística & dados numéricos
10.
Indoor Air ; 18(2): 144-55, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18333993

RESUMO

UNLABELLED: Used ventilation air filters have been shown to reduce indoor environmental quality and worker performance and increase symptoms, with effects stronger after reaction of filters with ozone. We analyzed data from the US EPA Building Assessment Survey and Evaluation (BASE) study to determine if ozone and specific filter media have interactive effects on building-related symptoms (BRS). We analyzed a subset of 34 buildings from the BASE study of 100 US office buildings to determine the separate and joint associations of filter medium [polyester/synthetic (PS) or fiberglass (FG)] and outdoor ozone concentration (above/below the median, 67.6 microg/m(3)) with BRS. Using logistic regression models and general estimating equations, we estimated odds ratios (ORs) and 95% confidence intervals for the association of filter medium, ozone, and filter medium x ozone with BRS. Relative to FG + low ozone, PS alone or high ozone alone, were each significantly (P < 0.05) associated only with fatigue/difficulty concentrating (ORs = 1.93 and 1.54, respectively). However, joint exposure to both PS + high ozone, relative to FG + low ozone, had significant associations with lower and upper respiratory, cough, eye, fatigue, and headache BRS (ORs ranged from 2.26 to 5.90). Joint ORs for PS + high ozone for lower and upper respiratory and headache BRS were much greater than multiplicative, with interaction P-values <0.10. Attributable risk proportion (ARP) estimates indicate that removing both risk factors might, given certain assumptions, reduce BRS by 26-62%. These findings suggest possible adverse health consequences from chemical interactions between outdoor ozone and PS filters in buildings. Results need confirmation before recommending changes in building operation. However, if additional research confirms causal relationships, ARP estimates indicate that appropriate filter selection may substantially reduce BRS in buildings, especially in high-ozone areas. PRACTICAL IMPLICATIONS: The results indicate that a better understanding of how filters interact with their environment is needed. While the mechanism is unknown and these findings need to be replicated, they indicate that the joint risk of BRS from polyester/synthetic filters and outdoor ozone above 67.6 microg/m(3) is much greater than the risk from each alone. These findings suggest potential reductions in BRS from appropriate selection of ventilation filter media or implementing strategies to reduce ozone entrained in building ventilation systems. If the relationships were found to be causal, filter replacement and ozone abatement should be undertaken.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Filtração/instrumentação , Ozônio/análise , Síndrome do Edifício Doente/etiologia , Adulto , Poluentes Atmosféricos/análise , Materiais de Construção , Estudos Transversais , Feminino , Filtração/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Material Particulado , Fatores de Risco , Síndrome do Edifício Doente/prevenção & controle , Estados Unidos , United States Environmental Protection Agency , Ventilação/métodos
11.
Indoor Air ; 18(2): 156-70, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18333994

RESUMO

UNLABELLED: Reactions between ozone and indoor contaminants may influence human health and indoor air quality. The U.S. EPA Building Assessment Survey and Evaluation (BASE) study data were analyzed for associations between ambient ozone concentrations and building-related symptom (BRS) prevalence. Multiple logistic regression (MLR) models, adjusted for personal, workplace, and environmental variables, revealed positive relationships (P < 0.05) between ambient ozone concentrations and upper respiratory (UR), dry eyes, neurological and headache BRS (odds ratios ranged from 1.03 to 1.04 per 10 mug/m(3) increase in ambient ozone concentrations). Other BRS had marginally significant relationships with ambient ozone (P < 0.10). A linear dose-response in UR symptoms was observed with increasing ambient ozone (P = 0.03); most other symptoms showed similar but not statistically significant trends. Ambient ozone correlated with indoor concentrations of some aldehydes, a pattern suggesting the occurrence of indoor ozone chemistry. Coupled with the MLR ambient ozone-BRS analysis, this correlation is consistent with the hypothesis that ozone-initiated indoor reactions play an important role in indoor air quality and building occupant health. Replication with increased statistical power and with longitudinal data is needed. If the observed associations are confirmed as causal, ventilation system ozone removal technologies could reduce UR BRS prevalence when higher ambient ozone levels are present. PRACTICAL IMPLICATIONS: This paper provides strong statistical evidence that supports (but does not prove) the hypothesis that ozone entrained into buildings from the outdoor air is involved in increasing the frequency that occupants experience and a range of upper and lower respiratory, mucosal and neurological symptoms by as much as a factor of 2 when ambient ozone levels increase from those found in low-ozone regions to those typical of high-ozone regions. Although replication is needed, the implication is that reducing the amount of ozone entrained into building ventilation systems, either by ambient pollution reduction or engineered gas-phase filtration, may substantially reduce the prevalence of these symptoms experienced by occupants.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Ozônio/análise , Síndrome do Edifício Doente/etiologia , Adulto , Relação Dose-Resposta a Droga , Monitoramento Ambiental , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Estações do Ano , Fatores Sexuais , Estados Unidos , United States Environmental Protection Agency , Ventilação/métodos
12.
Intern Med J ; 38(7): 592-8, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18715303

RESUMO

Chronic pancreatitis is a necroinflammatory process characterized pathologically by acinar atrophy and fibrosis and clinically by abdominal pain, diabetes and maldigestion. In this review we summarize some of the recent advances in the understanding of the pathogenesis of pancreatitis and how they have shaped our current understanding of chronic pancreatitis. We pay particular attention to advances in the genetic basis of idiopathic, hereditary and tropical pancreatitis as well as research into the relationship between alcohol and the pancreas. We have also reviewed current practices with respect to diagnosis and management of chronic pancreatitis.


Assuntos
Pancreatite Crônica/diagnóstico , Pancreatite Crônica/metabolismo , Alcoolismo/complicações , Alcoolismo/metabolismo , Antioxidantes/uso terapêutico , Humanos , Pâncreas/metabolismo , Pâncreas/patologia , Pancreatite Crônica/etiologia , Pancreatite Crônica/terapia
13.
Novartis Found Symp ; 285: 200-11; discussion 211-6, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17590996

RESUMO

Alcohol abuse is a major cause of pancreatitis, a condition that can manifest as both acute necroinflammation and chronic damage (acinar atrophy and fibrosis). It is generally accepted that alcohol-induced pancreatic injury is a consequence of the metabolism of alcohol by the pancreas (via the oxidative and non-oxidative pathways) producing the toxic metabolites acetaldehyde and fatty acid ethyl esters (FAEEs) respectively. Ethanol oxidation within the pancreas also leads to oxidant stress within the gland. Acetaldehyde, oxidant stress and FAEEs cause numerous molecular changes in pancreatic acinar cells which predispose the gland to autodigestion and necroinflammation. An important recent development relates to the identification of pancreatic stellate cells (PSCs) as the key mediators of alcohol-induced pancreatic fibrosis, when activated by ethanol, acetaldehyde or oxidant stress. Recent studies implicate the mitogen activated protein kinase (MAPK) pathway, a major signalling pathway in mammalian cells, as a critical regulator of the effects of ethanol and acetaldehyde on acinar cells as well as PSCs. Particularly important are the modulatory effects of ethanol and its metabolites on downstream transcription factors NF-kappaB and AP-1 (which regulate inflammatory responses via cytokine production) in acinar cells. In PSCs, additional signalling molecules identified as important to the process of ethanol and acetaldehyde-induced PSC activation include protein kinase C (PKC), phosphatidylinositol-3-kinase (PI3K) and peroxisome proliferator-activated receptor gamma (PPARgamma). Interestingly, cross-talk has been demonstrated between PI3K and MAPK in acetaldehyde-treated PSCs. The above advances in the identification of relevant signalling molecules may enable therapeutic targeting of these pathways so as to prevent/reduce alcohol-induced acute as well as chronic injury of the pancreas.


Assuntos
Acetaldeído/metabolismo , Consumo de Bebidas Alcoólicas/efeitos adversos , Etanol/toxicidade , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Pâncreas/metabolismo , Pancreatopatias/metabolismo , Transdução de Sinais/efeitos dos fármacos , Etanol/metabolismo , Humanos , Oxirredução , Estresse Oxidativo/fisiologia , PPAR gama/metabolismo , Pâncreas/efeitos dos fármacos , Pancreatopatias/induzido quimicamente , Fosfatidilinositol 3-Quinases , Proteína Quinase C/metabolismo , Transdução de Sinais/fisiologia
14.
Biochim Biophys Acta ; 1379(3): 314-24, 1998 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-9545590

RESUMO

The effects of ethanol on pancreatic digestive and lysosomal enzymes may be relevant to the pathogenesis of alcoholic pancreatitis since pancreatic enzymes are thought to play an important role in the development of pancreatic injury. Previous studies, using the Lieber-DeCarli pair-feeding model of ethanol administration, have demonstrated that ethanol significantly increases the content and gene expression of pancreatic enzymes. However, these findings have been questioned because, in the Lieber-DeCarli model, ethanol-fed rats have a lower carbohydrate intake than their pair-fed controls, making it difficult to ascribe any observed changes to ethanol alone. This study was designed to distinguish between the effects of ethanol and those of reduced dietary carbohydrate on pancreatic enzymes, using a quartet-feeding model of ethanol administration. Rats were fed liquid diets containing low (11%) and high (47%) amounts of carbohydrate, with and without ethanol, for four weeks. The effects of ethanol on pancreatic content and messenger RNA levels for digestive enzymes (trypsinogen, chymotrypsinogen and lipase) and a lysosomal enzyme (cathepsin B) were assessed. Ethanol feeding resulted in a significant increase in glandular content with a corresponding increase in mRNA levels for all four enzymes studied. By contrast, a reduction in dietary carbohydrate intake alone did not alter pancreatic content or gene expression for the above enzymes. These results indicate that (i) ethanol significantly increases the capacity of the acinar cells to synthesise digestive enzymes and the lysosomal enzyme cathepsin B, and (ii) these changes are due to ethanol itself and are not due to variations in dietary carbohydrate intake.


Assuntos
Etanol/administração & dosagem , Pâncreas/efeitos dos fármacos , Pâncreas/enzimologia , Animais , Animais Lactentes , Catepsina B/genética , Catepsina B/metabolismo , Quimotripsinogênio/genética , Quimotripsinogênio/metabolismo , Dieta , Carboidratos da Dieta/administração & dosagem , Lipase/genética , Lipase/metabolismo , Lisossomos/enzimologia , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Tripsina/genética , Tripsina/metabolismo
15.
Biochim Biophys Acta ; 1336(1): 89-98, 1997 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-9271254

RESUMO

Postulated mechanisms of alcoholic pancreatitis include (i) zymogen granule fragility facilitating intracellular activation of digestive enzymes and (ii) ductular obstruction by protein plugs. GP2, a pancreatic glycoprotein, stabilizes zymogen granule membranes and is an important constituent of pancreatic protein plugs. Therefore, this study examined the pancreatic content and messenger RNA levels of GP2 after chronic ethanol administration. Rats were fed liquid diets with or without ethanol, for four weeks. GP2 levels in pancreatic homogenates, crude zymogen granules and zymogen granule membrane fractions were assessed by immunoblotting. Messenger RNA levels for GP2 were measured by Northern and dot blotting of pancreatic RNA. Pancreatic GP2 levels were lower in ethanol-fed rats than in controls (GP2 levels expressed as % of control: 38.75 +/- 5.8, p < 0.001 in homogenate; 31.28 +/- 3.5, p < 0.0005 in crude zymogen granules and 22.89 +/- 5.4, p < 0.0005 in zymogen granule membranes). Messenger RNA levels for GP2 were unchanged after ethanol feeding. Chronic ethanol consumption decreases GP2 content of pancreatic homogenate and zymogen granules. This decrease could (i) result from an increased release into pancreatic juice thereby favouring protein plug formation and (ii) impair zymogen granule stability. Both these mechanisms could potentiate pancreatic damage.


Assuntos
Etanol/farmacologia , Pâncreas/efeitos dos fármacos , Fosforilases/metabolismo , Animais , Northern Blotting , Etanol/administração & dosagem , Masculino , Pâncreas/enzimologia , Fosforilases/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley
16.
Best Pract Res Clin Gastroenterol ; 17(4): 593-612, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12828957

RESUMO

Alcoholic pancreatitis is a major complication of alcohol abuse. Until recently, it was generally accepted that alcoholic pancreatitis was a chronic disease from the outset. However, evidence is now emerging in support of the 'necrosis-fibrosis' hypothesis that alcoholic pancreatitis begins as an acute process and that repeated episodes of acute injury lead to the changes of chronic pancreatitis (acinar atrophy and fibrosis) resulting in exocrine and endocrine dysfunction. The treatment of acute pancreatitis follows the regimen of bed rest, nasogastric suction, analgesia and intravenous support. The role of additional therapeutic measures such as prophylactic antibiotics, antioxidants and enteral nutrition in severe cases has not yet been precisely defined. The treatment of chronic pancreatitis involves attention to its three cardinal features: pain, maldigestion and diabetes. With respect to the pathogenesis of alcoholic pancreatitis, the focus of research over the past 30 years has shifted from the sphincter of Oddi and ductular abnormalities to the acinar cell itself. It has now been established that the acinar cell is capable of metabolizing alcohol and that direct toxic effects of alcohol and/or its metabolites on acinar cells may predispose the gland to injury in the presence of an appropriate trigger factor. A significant recent development relates to the characterization of pancreatic stellate cells, increasingly implicated in alcoholic pancreatic fibrosis. This chapter summarizes the natural history, clinical features, current trends in treatment as well as recent advances in our understanding of the pathogenesis of alcoholic pancreatitis.


Assuntos
Alcoolismo/complicações , Etanol/toxicidade , Pancreatite Alcoólica/etiologia , Pancreatite Alcoólica/terapia , Doença Aguda , Animais , Doença Crônica , Diabetes Mellitus/etiologia , Diabetes Mellitus/terapia , Fibrose , Predisposição Genética para Doença , Humanos , Mediadores da Inflamação/metabolismo , Síndromes de Malabsorção/etiologia , Síndromes de Malabsorção/terapia , Dor/etiologia , Manejo da Dor , Pâncreas/citologia , Pâncreas/efeitos dos fármacos , Pâncreas/enzimologia , Pâncreas/patologia , Pancreatite Alcoólica/diagnóstico , Pancreatite Alcoólica/patologia
17.
Alcohol Health Res World ; 21(1): 13-20, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-15706759

RESUMO

Pancreatitis is a potentially fatal inflammation of the pancreas often associated with long-term alcohol consumption. Symptoms may result from blockage of small pancreatic ducts as well as from destruction of pancreatic tissue by digestive enzymes. In addition, by-products of alcohol metabolism within the pancreas may damage cell membranes. Research on the causes of pancreatitis may support more effective disease management and provide hope for a potential cure.


Assuntos
Consumo de Bebidas Alcoólicas/fisiopatologia , Pâncreas/fisiopatologia , Pancreatite Alcoólica/fisiopatologia , Pancreatite Alcoólica/terapia , Consumo de Bebidas Alcoólicas/efeitos adversos , Consumo de Bebidas Alcoólicas/terapia , Humanos , Pâncreas/efeitos dos fármacos , Pâncreas/metabolismo , Pâncreas/patologia , Pancreatite Alcoólica/diagnóstico , Pancreatite Alcoólica/etiologia
18.
Life Sci ; 58(6): 485-92, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8569421

RESUMO

Both ethanol abuse and protein deficiency are well known associations of chronic pancreatitis. An early event in chronic pancreatitis is the deposition of protein plugs in small pancreatic ducts, leading to ductular obstruction and acinar cell damage. Lithostathine, a pancreatic secretory protein, is a major organic component of protein plugs. The aim of this study was to determine the effect of chronic ethanol administration and dietary protein deficiency, separately and in combination, on messenger RNA (mRNA) levels for pancreatic lithostathine. Male Sprague-Dawley rats were fed in groups of four, for four weeks, protein sufficient and protein deficient diets with or without ethanol. Messenger RNA levels for pancreatic lithostathine were assessed in all four groups. Both ethanol and protein deficiency, separately and in combination, increased mRNA levels for lithostathine. Thus, both chronic ethanol consumption and dietary protein deficiency increase the capacity of the pancreatic acinar cell to synthesize lithostathine.


Assuntos
Alcoolismo/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Etanol/toxicidade , Proteínas do Tecido Nervoso , Pâncreas/efeitos dos fármacos , Pâncreas/metabolismo , Pancreatite/metabolismo , Deficiência de Proteína/metabolismo , RNA Mensageiro/metabolismo , Alcoolismo/complicações , Animais , Sequência de Bases , Peso Corporal/efeitos dos fármacos , Doença Crônica , Litostatina , Masculino , Dados de Sequência Molecular , Tamanho do Órgão/efeitos dos fármacos , Pancreatite/etiologia , Ratos , Ratos Sprague-Dawley
19.
J Expo Anal Environ Epidemiol ; 9(6): 546-59, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10638840

RESUMO

The LBNL/QGI occupational carbon monoxide (CO) dosimeter (LOCD), a new, inexpensive CO passive sampler, was field-validated in an occupational exposure assessment study in the Moscone Convention Center (MCC) in San Francisco, CA in January, 1997. The LOCD measures time-weighed-average (TWA) CO exposures from 10 to 800 parts per million hours (ppm h; accuracy +/- 20%; precision 10 ppm h). This device represents a major improvement over currently available low-cost personal CO monitors. At the MCC, over 1000 workers set up and remove exhibitions. Forty propane-powered forklifts moved materials throughout the 42,000 m2 of exhibit halls. Diesel truck emissions enter the building via three internal underground loading docks. The LOCD was used to measure 154 worker exposures on 3 days. Sampler performance was compared to a standard method at 15 fixed sites. The geometric mean (GM) of all 154 exposures was 7 ppm (geometric standard deviation (GSD) = 1.6); 10% of the exposures was 10 ppm or more. Dock Walkers and Forklift Operators had the highest exposures (maximum = 34 ppm) with GM (GSD) of 9 (1.7) and 9 (1.6) ppm, respectively. Attendants and Installer/Decorators had the lowest exposures with GMs of 6 (1.6) and 7 (1.4), respectively. The Cal/OSHA personal exposure limit for CO is 25 ppm time-weighted average (TWA).


Assuntos
Poluentes Ocupacionais do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Monóxido de Carbono/análise , Exposição Ocupacional/análise , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Dosimetria Fotográfica , Humanos , Exposição Ocupacional/estatística & dados numéricos , São Francisco/epidemiologia , Emissões de Veículos/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA