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1.
Public Health Action ; 14(2): 76-81, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38957503

RESUMO

OBJECTIVE: To identify individual-level early warning indicators of virologic failure in HIV patients receiving antiretroviral therapy (ART) in South Africa. DESIGN: A matched case-control study of individuals with and without virologic failure (VF) (>5 months on ART and HIV-1 plasma viral load >1,000 copies/mL) was conducted between June 2014 and June 2018. Of the 1,000 participants enrolled in the parent cohort, 96 experienced VF, and 199 additional controls were identified from the parent cohort and matched 1:2 (some matched 1:3) for sex, age, ART duration, and site. Participants were interviewed while clinical, pharmacy refill, laboratory, and objective pharmacological data were obtained. Multivariate conditional logistic regression models were constructed using model selection to identify factors associated with VF. Significant determinants of VF were identified using an alpha level of 0.05. RESULTS: In a full conditional model, higher cumulative ART adherence, quantified using tenofovir-diphosphate concentrations in dried blood spots (OR 0.26) and medication possession ratio (OR 0.98) were protective against VF, whereas an increase in total depression score (OR 1.20) was predictive of VF. CONCLUSION: This analysis demonstrates the importance of depression as a key individual-level early warning indicator of VF. Efforts to address mental health concerns among patients with people living with HIV could improve virologic suppression.


OBJECTIF: Identifier les indicateurs d'alerte précoce au niveau individuel de l'échec virologique chez les patients séropositifs recevant un traitement antirétroviral (TAR) en Afrique du Sud. MÉTHODE: Une étude cas-témoins appariée de personnes avec et sans échec virologique (FV, pour l'anglais « virologic failure ¼) (>5 mois sous ART et charge virale plasmatique du VIH-1 >1 000 copies/ml) a été menée entre juin 2014 et juin 2018. Sur les 1 000 participants inscrits dans la cohorte parente, 96 ont présenté une FV et 199 témoins supplémentaires ont été identifiés dans la cohorte parentale et appariés 1:2 (certains appariés 1:3) pour le sexe, l'âge, la durée du TAR et le site. Les participants ont été interrogés pendant que des données cliniques, de renouvellement de pharmacie, de laboratoire et pharmacologiques objectives ont été obtenues. Des modèles de régression logistique conditionnelle multivariée ont été construits à l'aide d'une sélection de modèles pour identifier les facteurs associés à la FV. Les déterminants significatifs de la FV ont été identifiés à l'aide d'un niveau alpha de 0,05. RÉSULTATS: Dans un modèle conditionnel complet, une observance cumulative plus élevée du TAR, quantifiée à l'aide des concentrations de ténofovir-diphosphate dans les gouttes de sang séché (OR 0,26) et du ratio de possession de médicaments (OR 0,98) protégeait contre la FV, tandis qu'une augmentation du score de dépression totale (OR 1,20) était prédictive de la FV. CONCLUSION: Cette analyse démontre l'importance de la dépression en tant qu'indicateur précoce clé au niveau individuel de la FV. Les efforts visant à résoudre les problèmes de santé mentale chez les personnes vivant avec le VIH pourraient améliorer la suppression virologique.

2.
Int J Tuberc Lung Dis ; 28(5): 231-236, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38659143

RESUMO

BACKGROUNDCulture-based diagnostics are the gold standard for diagnosing pulmonary TB (PTB). We characterized culture practices by comparing cases with documented sputum culture to those without.METHODSUsing multivariable logistic regression, we examined associations between PTB case characteristics and no documented sputum culture reported to the U.S. National TB Surveillance System during 2011-2021.RESULTSAmong 69,538 PTB cases analyzed, no sputum culture attempt was documented for 5,869 (8%). Non-sputum culture specimens were documented for 54%, 80%, and 89% of cases without documented sputum culture attempts among persons aged <15 years, 15-64, and 65+ years, respectively; bronchial fluid and lung tissue were common non-sputum specimens among cases in persons >15 years old. Having no documented sputum culture was associated with age <15 years (aOR 23.84, 99% CI 20.09-28.27) or ≥65 years (aOR 1.22, 99% CI 1.07-1.39), culture of a non-sputum specimen (aOR 6.57, 99% CI 5.93-7.28), residence in a long-term care facility (aOR 1.58, 99% CI 1.23-2.01), and receiving TB care outside of a health department (aOR 1.79, 99% CI 1.61-1.98).CONCLUSIONSInability to obtain sputum from children and higher diagnostic suspicion for disease processes that require tissue-based diagnostics could explain these findings..


Assuntos
Escarro , Tuberculose Pulmonar , Humanos , Escarro/microbiologia , Estados Unidos , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/epidemiologia , Tuberculose Pulmonar/microbiologia , Adolescente , Masculino , Pessoa de Meia-Idade , Adulto , Adulto Jovem , Feminino , Idoso , Criança , Pré-Escolar , Lactente , Modelos Logísticos , Mycobacterium tuberculosis/isolamento & purificação
3.
Occup Med (Lond) ; 72(1): 25-27, 2022 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-34633045

RESUMO

BACKGROUND: There is an urgent need to address high levels of work-related violence (WRV) in Britain to improve the workplace experience of both employers and employees. AIMS: This study specifically explores prevalence rates of work-related violence assaults (WRVAs) for staff at high risk that have supervisor responsibilities and work full-time. METHODS: Five years of data were used for analysis from the Crime Survey of England and Wales (CSEW). Data were filtered for victims of crime from a working population in Britain. RESULTS: Forty-four per cent of respondents who are supervisors and have full-time jobs report that they had been victims of WRVAs. This figure is higher than other previous studies of WRV. CONCLUSIONS: The current study provides further alternative evidence to support high prevalence rates of WRV by selecting for analysis specific work characteristics data that are strongly associated with WRV (supervisor responsibilities and full-time work). It is therefore recommended that future work explores different means of intervention for organizations to implement within the workplace to reduce WRV and protect workers from harm.


Assuntos
Vítimas de Crime , Violência no Trabalho , Crime , Inglaterra/epidemiologia , Humanos , Violência , País de Gales/epidemiologia
4.
Occup Med (Lond) ; 66(7): 522-7, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27209323

RESUMO

BACKGROUND: Incidents of work-related violence (WRV) have increased over the years. These can be damaging to both individual psychological well-being and organizational performance. AIMS: To examine the prevalence and causes of customer-perpetrated WRV in Britain over a 12 year period. Demographic, work and perpetrator's personality characteristics were examined as predictors of WRV. METHODS: Data from the Crime Survey of England and Wales (CSEW) across 2001-13 were filtered specifically to explore responses from victims of customer-perpetrated crime within the working population. RESULTS: On average, 22% of all violent crimes committed by customers occurred in the workplace. Further analysis showed that differences in gender, age as well as managerial/supervisory duties, working hours, employment status, organizational size and occupation were significantly related to incidents of WRV. Perpetrators' personality characteristics were also perceived as predictors of WRV. CONCLUSIONS: This paper provides an alternative approach for reporting customer-perpetrated WRV. Violence at work is considered a widespread problem within the organizational studies literature, which can lead to a variety of stress-related symptoms in affected workers. Based on the current study's findings, a theoretical model is proposed to help combat customer-perpetrated WRV, and as a basis for future research.


Assuntos
Prevalência , Violência/estatística & dados numéricos , Violência/tendências , Local de Trabalho/estatística & dados numéricos , Adulto , Vítimas de Crime/estatística & dados numéricos , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Reino Unido , Local de Trabalho/normas
5.
Scand J Med Sci Sports ; 26(6): 620-9, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25946038

RESUMO

This study examined the time course of short-term training and detraining-induced changes in oxygen uptake ( V ˙ O 2 ) kinetics. Twelve men (24 ± 3 years) were assigned to either a 50% or a 70% of V ˙ O 2 m a x training intensity (n = 6 per group). V ˙ O 2 was measured breath-by-breath. Changes in deoxygenated-hemoglobin concentration (Δ[HHb]) were measured by near-infrared spectroscopy. Moderate-intensity exercise on-transient V ˙ O 2 and Δ[HHb] were modeled with a mono-exponential and normalized (0-100% of response) and the [ H H b ] / V ˙ O 2 ratio was calculated. Similar changes in time constant of V ˙ O 2 ( t V ˙ O 2 ) were observed in both groups. The combined group mean for t V ˙ O 2 decreased ∼14% (32.3 to 27.9 s, P < 0.05) after one training session with a further ∼11% decrease (27.9 to 24.8 s, P < 0.05) following two training sessions. The t V ˙ O 2 p remained unchanged throughout the remaining of training and detraining. A significant "overshoot" in the [ H H b ] / V ˙ O 2 ratio was decreased (albeit not significant) after one training session, and abolished (P < 0.05) after the second one, with no overshoot observed thereafter. Speeding of V ˙ O 2 kinetics was remarkably quick with no further changes being observed with continuous training or during detraining. Improve matching of local O2 delivery to O2 utilization is a mechanism proposed to influence this response.


Assuntos
Consumo de Oxigênio , Oxigênio/metabolismo , Condicionamento Físico Humano/fisiologia , Aptidão Física/fisiologia , Adulto , Descondicionamento Cardiovascular/fisiologia , Teste de Esforço , Hemoglobinas/metabolismo , Humanos , Cinética , Masculino , Condicionamento Físico Humano/métodos , Troca Gasosa Pulmonar , Músculo Quadríceps/metabolismo , Adulto Jovem
8.
Health Phys ; 103(6): 714-31, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23281507

RESUMO

Graphic methods for displaying uncertainty are often the most concise and informative way to communicate abstract concepts. Presentation methods currently in use for the display and interpretation of scientific uncertainty are reviewed. Numerous subjective and objective uncertainty display methods are presented, including qualitative assessments, node and arrow diagrams, standard statistical methods, box-and-whisker plots,robustness and opportunity functions, contribution indexes, probability density functions, cumulative distribution functions, and graphical likelihood functions.


Assuntos
Ciência/métodos , Incerteza , Gráficos por Computador , Modelos Teóricos , Probabilidade , Estatística como Assunto
9.
Ann N Y Acad Sci ; 1215: 131-7, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21261651

RESUMO

Studies with resVida(®) (a high purity trans-resveratrol) show that trans-resveratrol is a substance of low oral toxicity. An acceptable daily intake (ADI) in food of 450 mg/day has been defined, a level well beyond natural dietary intake of trans-resveratrol. The ADI was based on no-observed-adverse-effect-levels (NOAELs) of 750 mg/kg bw/day in 13-week developmental toxicity studies by the dietary route and a standard safety margin of 100. In studies by gavage, the kidney and bladder are target organs at very high dosages (2,000-3,000 mg/kg bw/day). Six-month studies in rat and rabbit models show no significant increase in toxicity in comparison to 4-week studies. Lower quoted NOAELs in gavage studies (ca. 300 mg/kg bw/day) potentially reflect more rapid bioavailability, but different dosage regimes complicate comparisons. Short-term studies show no genotoxicity in vivo. A 6-month mouse carcinogenicity model showed no increase in tumors. Clinical data support an ADI of at least 450 mg/day, and kinetic data from the DSM 13-week toxicity study also support the expectation of no increase in toxicity with longer term intake.


Assuntos
Contaminação de Medicamentos , Estilbenos/efeitos adversos , Estilbenos/isolamento & purificação , Animais , Contaminação de Medicamentos/prevenção & controle , Humanos , Reprodução/efeitos dos fármacos , Reprodução/fisiologia , Resveratrol , Estilbenos/química , Testes de Toxicidade/métodos , Testes de Toxicidade/normas
10.
Anaesthesia ; 65(5): 453-61, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20522030

RESUMO

Oocyte retrieval is a procedure where sedation is recommended. This paper presents the process of setting up a new, non-anaesthetist delivered service in our institution, the development of safety systems and the audit data we have used to assure quality, effectiveness and safety. Logbook data were collected for 4342 cases, with detailed audit data collected for 260 cases. Safety is acceptable with a respiratory adverse incident rate of 0.5/1000 (95% CI 0.1-1.6/1000 cases). Unplanned, direct anaesthetic assistance was required in 3.5/1000 cases (95% CI 1.7-5.3/1000 cases). Anaesthetic advice was required in 7.5% cases (95% CI 4.2-10.7%) at the inception of the service, but rarely once established: 0.6% (95% CI 0.2-1.0%). Nearly all patients (99%) would have the same sedation method again, no patients required admission, and patients' co-operation was judged by the operating surgeon as very good or good in 91% of cases.


Assuntos
Alfentanil/administração & dosagem , Sedação Consciente/métodos , Hipnóticos e Sedativos/administração & dosagem , Recuperação de Oócitos/métodos , Propofol/administração & dosagem , Competência Clínica , Esquema de Medicação , Feminino , Humanos , Infusões Intravenosas , Auditoria Médica
11.
Food Chem Toxicol ; 44(5): 636-50, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16387402

RESUMO

Green tea extract and its principal active ingredient, epigallocatechin gallate (EGCG), are gaining attention and increased usage due to their healthful properties. Despite the increasing demand for these products, few studies have examined their safety. The toxicity of purified green tea extracts containing high concentrations of EGCG have been evaluated in a series of studies in order to define the safety of Teavigo, a high-concentration EGCG extract produced by the same novel method. Topical EGCG preparations caused minor dermal irritation in rats and guinea pigs, but not rabbits, and was a moderate dermal sensitizing agent in the guinea pig maximization test. A rabbit eye irritation test produced a strong enough response to not warrant any further testing in this assay. An oral dose delivering 2000 mg EGCG preparation/kg was lethal to rats; whereas, a dose of 200 mg EGCG/kg induced no toxicity. The dietary administration of EGCG preparation to rats for 13 weeks was not toxic at doses up to 500 mg/kg/day. Similarly, no adverse effects were noted when 500 mg EGCG preparation/kg/day was administered to pre-fed dogs in divided doses. This dose caused morbidity when administered to fasted dogs as a single bolus dose, although this model was considered an unrealistic comparison to the human condition. From these studies a no-observed adverse effect level of 500 mg EGCG preparation/kg/day was established.


Assuntos
Antioxidantes/toxicidade , Camellia sinensis/química , Catequina/análogos & derivados , Dermatite Alérgica de Contato , Administração Oral , Administração Tópica , Animais , Antioxidantes/isolamento & purificação , Antioxidantes/farmacocinética , Área Sob a Curva , Catequina/isolamento & purificação , Catequina/farmacocinética , Catequina/toxicidade , Dermatite Alérgica de Contato/etiologia , Dermatite Alérgica de Contato/imunologia , Cães , Relação Dose-Resposta a Droga , Olho/efeitos dos fármacos , Jejum , Feminino , Cobaias , Masculino , Nível de Efeito Adverso não Observado , Coelhos , Distribuição Aleatória , Ratos , Fatores Sexuais , Absorção Cutânea/efeitos dos fármacos , Especificidade da Espécie , Testes de Toxicidade Aguda
12.
Food Chem Toxicol ; 44(5): 651-61, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16410036

RESUMO

Green tea and its principal active ingredient, epigallocatechin gallate (EGCG), have been demonstrated to have anticancer properties through interactions with multiple biochemical processes. Since these processes are often crucial in normal fetal development it is important to evaluate the potential effects of EGCG on the fetus. EGCG preparations of >91% purity were administered to pregnant rats during organogenesis and development in order to define the safety of Teavigo, a high-concentration EGCG extract produced by the same novel method. In an initial preliminary study using subcutaneous and gavage routes, there was no evidence of any direct embryo-fetal toxicity, although some maternal toxicity was seen. In the main teratogenicity study, feeding pregnant rats diets supplemented at 1400, 4200 or 14,000 ppm during organogenesis was non-toxic to dams or fetuses. A two-generation study in rats fed 1200, 3600 or 12,000 ppm EGCG preparation showed no adverse effects on reproduction or fertility. The highest dose reduced the growth rate of offspring, and there was a slight increase in pup loss. A growth effect among pups was also seen at 3600 ppm, but in the second generation only. The lowest dose was considered the overall no-observed adverse effect level (NOAEL). As dams consumed twice the amount of feed during the crucial lactation period, the NOAEL was equivalent to 200 mg/kg/day EGCG preparation.


Assuntos
Anticarcinógenos/toxicidade , Antimutagênicos/toxicidade , Catequina/análogos & derivados , Feto/efeitos dos fármacos , Reprodução/efeitos dos fármacos , Teratogênicos , Anormalidades Induzidas por Medicamentos , Administração Oral , Animais , Animais Recém-Nascidos/crescimento & desenvolvimento , Animais Recém-Nascidos/fisiologia , Anticarcinógenos/uso terapêutico , Catequina/toxicidade , Relação Dose-Resposta a Droga , Feminino , Injeções Subcutâneas , Tamanho da Ninhada de Vivíparos/efeitos dos fármacos , Masculino , Nível de Efeito Adverso não Observado , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Ratos , Ratos Sprague-Dawley , Ratos Wistar
13.
Food Chem Toxicol ; 44(5): 626-35, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16364532

RESUMO

Public interest in green tea has grown recently due to the potential health benefits from its consumption. Epigallocatechin gallate (EGCG), a principal polyphenolic component of green tea, is considered key to these healthful qualities. Although numerous studies have evaluated the anti-cancer effects of green tea and EGCG, few have examined the safety of EGCG consumption. The genotoxic potential of a concentrated EGCG preparation was tested in Salmonella and L5178Y tk+/- mouse lymphoma cell assays to further define the safety of Teavigo, a high-concentration EGCG extract of Camellia sinensis leaves produced by the same novel method. No mutagenic activity was detected in the bacterial system; however, a clastogenic 'trend' from the formation of hydrogen peroxide was noted in the murine cells. The oral administration of 500, 1000, or 2000 mg EGCG/kg to mice did not induce micronuclei formation in bone marrow cells. Similarly, administering 400, 800, or 1200 mg EGCG/kg/day in their diet for 10 days did not induce bone marrow cell micronuclei and produced plasma EGCG concentrations comparable to those reported in human studies. The intravenous injection of 10, 25 and 50 mg EGCG/kg/day to rats resulted in much higher plasma concentrations and demonstrated an absence of genotoxic effects. From these studies, it is concluded that Teavigo (EGCG) is not genotoxic.


Assuntos
Anticarcinógenos/toxicidade , Antioxidantes/toxicidade , Camellia sinensis/química , Catequina/análogos & derivados , Qualidade de Produtos para o Consumidor , Animais , Anticarcinógenos/isolamento & purificação , Anticarcinógenos/farmacocinética , Antioxidantes/isolamento & purificação , Antioxidantes/farmacocinética , Bioensaio , Catequina/isolamento & purificação , Catequina/farmacocinética , Catequina/toxicidade , Relação Dose-Resposta a Droga , Feminino , Humanos , Peróxido de Hidrogênio/análise , Masculino , Camundongos , Camundongos Endogâmicos , Testes para Micronúcleos , Testes de Mutagenicidade , Ratos , Ratos Wistar , Salmonella/genética , Células Tumorais Cultivadas
14.
J Pers Soc Psychol ; 81(2): 206-19, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11519927

RESUMO

In 3 studies, we examined the hypothesis that the effects of stereotype usage on target judgments are moderated by causal uncertainty beliefs and related accuracy goal structures. In Study 1, we focused on the role of chronically accessible causal uncertainty beliefs as predictors of a target's level of guilt for an alleged academic misconduct offense. In Study 2, we examined the role of chronic causal uncertainty reduction goals and a manipulated accuracy goal; in Study 3, we investigated the role of primed causal uncertainty beliefs on guilt judgments. In all 3 studies, we found that activation of causal uncertainty beliefs and accuracy concerns was related to a reduced usage of stereotypes. Moreover, this reduction was not associated with participants' levels of perceived control, depression, state affect, need for cognition, or personal need for structure. Results are discussed in terms of their implications for the model of causal uncertainty and, more generally, in terms of the motivational processes underlying stereotype usage.


Assuntos
Cultura , Julgamento , Motivação , Probabilidade , Estereotipagem , Adulto , Feminino , Humanos , Individualidade , Masculino , Modelos Psicológicos
15.
AIHAJ ; 62(1): 28-35, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11258865

RESUMO

To ensure the health and safety of workers, integrated industrial hygiene methodologies often include biological monitoring of the workers to help understand their exposure to chemicals. To this end, a field-portable breath-analysis system was developed and tested to measure selected solvents in exhaled air. The exhaled breath data were evaluated using a physiologically based pharmacokinetic (PBPK) model to relate exposure to tissue dose. The system was designed to monitor workers every time they entered or left a work environment--a vast improvement over current 8-hour integrated monitoring strategies. The system combines (1) chemical dosimeters to measure airborne contaminant levels (analyzed in the field/ workplace); (2) real-time breath analysis to quantitate exposure; and 3) PBPK models to estimate internal target tissue dose. To evaluate the system, field tests were conducted at two locations: (1) at an incinerator in Tennessee monitoring benzene and toluene exposures; and (2) a waste repackaging facility in Washington State where hexane, trimethylbenzene, and methylene chloride was monitored. Exhaled breath was sampled and analyzed before and after each specific job task, which ranged from 15 min to 8 hours in duration. In both field studies several volunteers had posttask breath levels higher than pretask levels. The greatest increase corresponded to 573 ppb for methylene chloride and 60 ppb for toluene. Compared with breath analysis, the chemical dosimeters underpredicted the dosimetry, particularly for longer sampling intervals when the volume of air sampled may have diluted exposures. The results of the field studies illustrate the utility of monitoring workers for exposures throughout the day, particularly when job-specific tasks may indicate a potential for exposure.


Assuntos
Poluentes Ocupacionais do Ar/análise , Testes Respiratórios/instrumentação , Substâncias Perigosas/farmacocinética , Exposição Ocupacional/análise , Testes Respiratórios/métodos , Desenho de Equipamento , Humanos , Incineração , Tennessee , Volatilização , Washington
16.
J Neuroimmunol ; 108(1-2): 73-81, 2000 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-10900340

RESUMO

Multiple sclerosis (MS) is an immune-mediated demyelinating disease that could be triggered by a viral infection. Coronaviruses induce an MS-like disease in rodents, are neuroinvasive in humans and can infect primary cultures of human astrocytes and microglia. Infection of the human astrocytic cell line U-373MG by the OC43 strain of human coronavirus caused an upregulation of IL-6, TNF-alpha, and MCP-1 mRNA expression. This virus also modulated the activity of matrix metalloproteinases-2 and -9 and augmented nitric oxide production in both U-373MG cells and the human microglial cell line CHME-5. Thus, a coronaviral infection of glial cells could lead to the production of inflammatory molecules that have been associated with central nervous system pathologies such as MS.


Assuntos
Coronavirus Humano OC43 , Coronavirus/fisiologia , Regulação da Expressão Gênica , Neuroglia/metabolismo , Neuroglia/virologia , Astrócitos/enzimologia , Astrócitos/imunologia , Astrócitos/metabolismo , Astrócitos/virologia , Linhagem Celular , Quimiocina CCL2/genética , Humanos , Interleucina-6/genética , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Microglia/enzimologia , Microglia/imunologia , Microglia/metabolismo , Microglia/virologia , Esclerose Múltipla/metabolismo , Esclerose Múltipla/virologia , Neuroglia/enzimologia , Neuroglia/imunologia , Óxido Nítrico/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fator de Necrose Tumoral alfa/genética , Regulação para Cima
17.
Toxicol Sci ; 56(1): 61-72, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10869454

RESUMO

The development and validation of noninvasive techniques for estimating the dermal bioavailability of solvents in contaminated soil and water can facilitate the overall understanding of human health risk. To assess the dermal bioavailability of trichloroethylene (TCE), exhaled breath was monitored in real time using an ion trap mass spectrometer (MS/MS) to track the uptake and elimination of TCE from dermal exposures in rats and humans. A physiologically based pharmacokinetic (PBPK) model was used to estimate total bioavailability. Male F344 rats were exposed to TCE in water or soil under occluded or nonoccluded conditions by applying a patch to a clipper-shaved area of the back. Rats were placed in off-gassing chambers and chamber air TCE concentration was quantified for 3-5 h postdosing using the MS/MS. Human volunteers were exposed either by whole-hand immersion or by attaching patches containing TCE in soil or water on each forearm. Volunteers were provided breathing air via a face mask to eliminate inhalation exposure, and exhaled breath was analyzed using the MS/MS. The total TCE absorbed and the dermal permeability coefficient (K(P)) were estimated for each individual by optimization of the PBPK model to the exhaled breath data and the changing media and/or dermal patch concentrations. Rat skin was significantly more permeable than human skin. Estimates for K(P) in a water matrix were 0.31 +/- 0.01 cm/h and 0.015 +/- 0.003 cm/h in rats and humans, respectively. K(P) estimates were more than three times higher from water than soil matrices in both species. K(P) values calculated using the standard Fick's Law equation were strongly affected by exposure length and volatilization of TCE. In comparison, K(P) values estimated using noninvasive real-time breath analysis coupled with the PBPK model were consistent, regardless of volatilization, exposure concentration, or duration.


Assuntos
Absorção Cutânea , Pele/metabolismo , Tricloroetileno/farmacocinética , Administração Cutânea , Animais , Disponibilidade Biológica , Testes Respiratórios/métodos , Feminino , Humanos , Masculino , Espectrometria de Massas , Modelos Biológicos , Ratos , Ratos Endogâmicos F344 , Tricloroetileno/administração & dosagem
18.
Int J Occup Environ Health ; 6(2): 96-103, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10828137

RESUMO

Realistic estimates of percutaneous absorption following exposures to solvents in the workplace, or through contaminated soil and water, are critical to understanding human health risks. A method was developed to determine dermal uptake of solvents under non-steady-state conditions using real-time breath analysis in rats, monkeys, and humans. The exhaled breath was analyzed using an ion-trap mass spectrometer, which can quantitate chemicals in the exhaled breath stream in the 1-5 ppb range. The resulting data were evaluated using physiologically-based pharmacokinetic (PBPK) models to estimate dermal permeability constants (Kp) under various exposure conditions. The effects of exposure matrix (soil versus water), occlusion versus non-occlusion, and species differences on the absorption of methyl chloroform, trichloroethylene, and benzene were compared. Exposure concentrations were analyzed before and at 0.5-hour intervals throughout the exposures. The percentage of each chemical absorbed and the corresponding Kp were estimated by optimization of the PBPK model to the medium concentration and the exhaled-breath data. The method was found to be sufficiently sensitive for animal and human dermal studies at low exposure concentrations over small body surface areas, for short periods, using non-steady-state exposure conditions.


Assuntos
Exposição Ocupacional/análise , Compostos Orgânicos/metabolismo , Absorção Cutânea , Animais , Testes Respiratórios , Humanos , Macaca mulatta , Modelos Biológicos , Exposição Ocupacional/efeitos adversos , Compostos Orgânicos/efeitos adversos , Ratos , Volatilização
19.
Toxicol Sci ; 54(1): 42-51, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10746930

RESUMO

Due to the large surface area of the skin, percutaneous absorption has the potential to contribute significantly to the total bioavailability of some compounds. Breath elimination data, acquired in real-time using a novel MS/MS system, was assessed using a PBPK model with a dermal compartment to determine the percutaneous absorption of methyl chloroform (MC) in rats and humans from exposures to MC in non-occluded soil or occluded water matrices. Rats were exposed to MC using a dermal exposure cell attached to a clipper-shaved area on their back. The soil exposure cell was covered with a charcoal patch to capture volatilized MC and prevent contamination of exhaled breath. This technique allowed the determination of MC dermal absorption kinetics under realistic, non-occluded conditions. Human exposures were conducted by immersing one hand in 0.1% MC in water, or 0.75% MC in soil. The dermal PBPK model was used to estimate skin permeability (Kp) based on the fit of the exhaled breath data. Rat skin K(p)s were estimated to be 0.25 and 0.15 cm/h for MC in water and soil matrices, respectively. In comparison, human permeability coefficients for water matrix exposures were 40-fold lower at 0.006 cm/h. Due to evaporation and differences in apparent Kp, nearly twice as much MC was absorbed from the occluded water (61.3%) compared to the non-occluded soil (32.5%) system in the rat. The PBPK model was used to simulate dermal exposures to MC-contaminated water and soil in children and adults using worst-case EPA default assumptions. The simulations indicate that neither children nor adults will absorb significant amounts of MC from non-occluded exposures, independent of the length of exposure. The results from these simulations reiterate the importance of conducting dermal exposures under realistic conditions.


Assuntos
Tricloroetanos/farmacocinética , Administração Tópica , Adulto , Animais , Disponibilidade Biológica , Composição Corporal/fisiologia , Testes Respiratórios , Cromatografia Líquida de Alta Pressão , Humanos , Masculino , Espectrometria de Massas , Modelos Biológicos , Ratos , Ratos Endogâmicos F344 , Absorção Cutânea , Solventes , Distribuição Tecidual , Tricloroetanos/administração & dosagem
20.
Plant Cell ; 11(3): 445-58, 1999 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10072403

RESUMO

A MADS box gene, FLF (for FLOWERING LOCUS F ), isolated from a late-flowering, T-DNA-tagged Arabidopsis mutant, is a semidominant gene encoding a repressor of flowering. The FLF gene appears to integrate the vernalization-dependent and autonomous flowering pathways because its expression is regulated by genes in both pathways. The level of FLF mRNA is downregulated by vernalization and by a decrease in genomic DNA methylation, which is consistent with our previous suggestion that vernalization acts to induce flowering through changes in gene activity that are mediated through a reduction in DNA methylation. The flf-1 mutant requires a greater than normal amount of an exogenous gibberellin (GA3) to decrease flowering time compared with the wild type or with vernalization-responsive late-flowering mutants, suggesting that the FLF gene product may block the promotion of flowering by GAs. FLF maps to a region on chromosome 5 near the FLOWERING LOCUS C gene, which is a semidominant repressor of flowering in late-flowering ecotypes of Arabidopsis.


Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Proteínas de Homeodomínio/genética , Proteínas de Plantas/genética , Proteínas Repressoras/genética , Fatores de Transcrição/genética , Metilação de DNA , DNA de Plantas/metabolismo , Regulação para Baixo , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS , Polimorfismo de Fragmento de Restrição , RNA Mensageiro/metabolismo , RNA de Plantas/metabolismo
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