RESUMO
Single-crystal chemical vapour deposition (CVD) diamond detectors are an established transmissive synchrotron beamline diagnostic instrument used for beam position and beam intensity monitoring. A recently commercialized alternative is silicon carbide (4H-SiC) devices. These have the potential to provide the same diagnostic information as commercially available single-crystal CVD diamond X-ray beam position monitors, but with a much larger transmissive aperture. At Diamond Light Source an experimental comparison of the performance of single-crystal CVD diamond and 4H-SiC X-ray beam position monitors has been carried out. A quantitative comparison of their performance is presented in this paper. The single-crystal diamond and 4H-SiC beam position monitors were installed in-line along the synchrotron X-ray beam path enabling synchronous measurements at kilohertz rates of the beam motion from both devices. The results of several tests of the two position monitors' performance are presented: comparing signal uniformity across the surface of the detectors, comparing kHz intensity measurements, and comparing kHz beam position measurements from the detectors. Each test is performed with a range of applied external bias voltages. A discussion of the benefits and limitations of 4H-SiC and single-crystal CVD diamond detectors is included.
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A method to simulate beam properties observed at the beamline sample-point in the presence of motion of optical components has been developed at Diamond Light Source. A series of stationary ray-tracing simulations are used to model the impact on the beam stability caused by dynamic motion of optical elements. Ray-tracing simulations using SHADOW3 in OASYS, completed over multiple iterations and stitched together, permit the modelling of a pseudo-dynamic beamline. As beamline detectors operating at higher frequencies become more common, beam stability is crucial. Synchrotron ring upgrades to low-emittance lattices require increased stability of beamlines in order to conserve beam brightness. By simulating the change in beam size and position, an estimate of the impact the motion of various components have on stability is possible. The results presented in this paper focus on modelling the physical vibration of optical elements. Multiple beam parameters can be analysed in succession without manual input. The simulation code is described and the initial results obtained are presented. This method can be applied during beamline design and operation for the identification of optical elements that may introduce large errors in the beam properties at the sample-point.
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PURPOSE: Lateral abdominal wall hernias are rare defects but, due to their location, repair is difficult, and recurrence is common. Few studies exist to support a standard protocol for repair of these lateral hernias. We hypothesized that anchoring our repair to fixed bony structures would reduce recurrence rates. METHODS: A retrospective review of all patients who underwent lateral hernia repair at our institution was performed. RESULTS: Eight cases (seven flank and one thoracoabdominal) were reviewed. The median defect size was 105 cm2 (range 36-625 cm2). The median operative time was 185 min (range 133-282 min). There were no major complications. One patient who was repaired without mesh attachment to bony landmarks developed a recurrence at ten months and subsequently underwent reoperation. Patients with mesh secured to bony landmarks were recurrence free at a median follow-up of 171 days. CONCLUSIONS: Lateral hernias present a greater challenge due to their anatomic location. An open technique with mesh fixation to bony structures is a promising solution to this complex problem.
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Hérnia Abdominal/cirurgia , Herniorrafia/métodos , Telas Cirúrgicas , Músculos Abdominais/cirurgia , Parede Abdominal/cirurgia , Adulto , Idoso , Procedimentos Cirúrgicos Eletivos , Feminino , Hérnia Abdominal/classificação , Herniorrafia/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos de Cirurgia Plástica/efeitos adversos , Procedimentos de Cirurgia Plástica/métodos , Recidiva , Reoperação , Estudos Retrospectivos , Telas Cirúrgicas/efeitos adversos , Parede Torácica/cirurgiaRESUMO
BACKGROUND: Interventions to prevent childhood obesity increasingly focus on infant feeding, but demonstrate inconsistent effects. A comprehensive qualitative evidence synthesis is essential to better understand feeding behaviours and inform intervention development. The aim of this study is to synthesize evidence on perceptions and experiences of infant feeding and complementary feeding recommendations. METHODS: Databases CINAHL, EMBASE, MEDLINE, PsycINFO, Academic Search Complete, SocIndex and Maternity and Infant Care were searched from inception to May 2017. Eligible studies examined parents' experiences of complementary feeding of children (<2 years). Data were synthesized using thematic synthesis. RESULTS: Twenty-five studies met inclusion criteria for review. Four key themes emerged. 'Guidelines and advice' highlights variety and inconsistencies between sources of complementary feeding information. 'Stage of weaning' describes infant feeding as a process involving different stages. 'Knowing and trying' outlines parents' engagement in feeding approaches based on instinct, prior experience or trial and error. 'Daily life' highlights problematic cost and time constraints for parents. DISCUSSION: Parents predominantly understand and want to engage in healthy feeding processes. Consideration of infant feeding as a process that changes over time is necessary to support parents. Provision of clear, consistent information and guidance from trusted sources on when, what and how to feed is also essential.
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Aleitamento Materno , Comportamento Alimentar/psicologia , Fenômenos Fisiológicos da Nutrição do Lactente , Pais , Adulto , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Lactente , Recém-Nascido , Masculino , Pais/educação , Educação de Pacientes como Assunto , Obesidade Infantil/prevenção & controle , Gravidez , Pesquisa QualitativaRESUMO
Fatigue syndromes exist on a continuum of severity from mild and transient to the disabling chronic fatigue syndrome, with oxidative stress linked to its pathogenesis. A thermolabile gliadin-combined plant superoxide dismutase (SOD) extract has shown potential in clinical trials as a therapeutic antioxidant. This study investigated the effects of 12 weeks of 500 mg/day of a SOD/gliadin supplement on fatigue. Thirty-eight women aged 50-65 years with self-perceived fatigue entered this randomized, double-blind, placebo-controlled trial. The primary outcome measure was general fatigue determined by the Multidimensional Fatigue Inventory (MFI). Secondary outcome measures included other measures of fatigue from the MFI and blood measures of oxidative stress, antioxidant status and hormones. There were no significant (P>0.05) differences between, or within groups, for decreases in general fatigue (active=1.6%, placebo=4.1%). There were no within or between group differences (P>0.05) in other measures of fatigue (physical fatigue, reduced activity, reduced motivation, mental fatigue and total fatigue score). In regard to the biochemical measures, there were non-significant (P>0.05) differences in increases in plasma SOD activity (active=7.1%, placebo=12.2%), plasma GPx activity (active=2.4%, placebo=0.7%), red blood cell GPx activity (active=9.8%, placebo=4.4%). Markers of oxidative stress were decreased but there were no differences (P>0.05) within or between groups; malondialdehyde (active=4.1%, placebo=1.6%), F-2 isoprostanes (active=14.7%, placebo=22.4%). There was a trend (P=0.08) for a decrease in cortisol in the active group (24.6%), however this was not significantly different from the decrease in the placebo participants (4.1%). DHEA differences were not significant (P<0.05) and declined 1.3% in the active group and 14.4% in the placebo group. In summary, the thermolabile SOD/gliadin supplement had no significant effect on self-perceived fatigue, antioxidants, oxidative stress or hormones in women aged 50-65 years.
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Antioxidantes/uso terapêutico , Cucumis/química , Suplementos Nutricionais , Fadiga/tratamento farmacológico , Gliadina/uso terapêutico , Extratos Vegetais/uso terapêutico , Superóxido Dismutase/uso terapêutico , Atividades Cotidianas , Idoso , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Desidroepiandrosterona/sangue , Método Duplo-Cego , Combinação de Medicamentos , F2-Isoprostanos/sangue , Fadiga/sangue , Feminino , Gliadina/farmacologia , Hormônios/sangue , Humanos , Hidrocortisona/sangue , Malondialdeído/sangue , Fadiga Mental/sangue , Fadiga Mental/tratamento farmacológico , Pessoa de Meia-Idade , Motivação/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Percepção , Extratos Vegetais/farmacologia , Autoimagem , Superóxido Dismutase/sangue , Superóxido Dismutase/farmacologiaRESUMO
Eighty-two patients with adenocarcinoma in situ of the cervix managed at Royal Prince Alfred Hospital were reviewed and data were collected on those treated by cold knife cone biopsy (n= 38) and laser cone biopsy (n= 44). No differences were found in patient age, cytologic or referral history, or outcomes. Having laser excision did not compromise margin status or subsequent management. Invasive disease was found in 24 patients, 16 of whom were managed conservatively with good outcome. Twelve of these were in the laser cone group. In those patients from both groups managed conservatively, there was only one recurrence, squamous preinvasive disease after 8 years. Laser cone biopsy is as effective as cold knife cone biopsy with no compromise of outcome for these patients.
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Adenocarcinoma/cirurgia , Carcinoma in Situ/cirurgia , Conização/métodos , Terapia a Laser , Neoplasias do Colo do Útero/cirurgia , Adenocarcinoma/patologia , Adulto , Idoso , Biópsia , Carcinoma in Situ/patologia , Feminino , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Estudos Retrospectivos , Resultado do Tratamento , Neoplasias do Colo do Útero/patologiaRESUMO
In this double-blind, placebo-controlled, crossover study we compared the bronchoprotective effects of formoterol 12 microg inhaled via an HFA-134a inhaler (Modulite HFA) versus a CFC and a DPI device in 38 patients with mild-to-moderate persistent asthma. All three formoterol preparations significantly increased methacholine PD20 and FEV1 and improved small airway function parameters compared with placebo (p < 0.001). No significant differences were observed between formoterol formulations. In conclusion, Modulite HFA formoterol was found to be an effective and well tolerated treatment in patients with asthma, with comparable efficacy to current formoterol preparations.
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Propelentes de Aerossol , Asma/tratamento farmacológico , Broncodilatadores/administração & dosagem , Clorofluorcarbonetos , Etanolaminas/administração & dosagem , Hidrocarbonetos Fluorados , Adulto , Asma/sangue , Asma/diagnóstico , Asma/fisiopatologia , Glicemia/metabolismo , Testes de Provocação Brônquica , Broncoconstritores , Broncodilatadores/uso terapêutico , Método Duplo-Cego , Esquema de Medicação , Etanolaminas/uso terapêutico , Feminino , Volume Expiratório Forçado/efeitos dos fármacos , Fumarato de Formoterol , Humanos , Masculino , Inaladores Dosimetrados , Cloreto de Metacolina , Pessoa de Meia-Idade , Nebulizadores e Vaporizadores , Potássio/sangue , PósRESUMO
AIMS: The aim of this study was to compare the variability and sensitivity of impulse oscillometry (R5, X5 and RF), plethysmography (Raw and sGaw) and spirometry (FEV1, FVC and MMEF) in order to determine the most powerful technique for assessing bronchodilation in COPD clinical trials. METHODS: Twenty-four patients with COPD had impulse oscillometry, plethysmography and spirometry measured twice 30 mins apart, to determine variability. Then ascending doses of salbutamol (20, 50, 100, 200, 400 and 800 microg) were given and the same measurements made after each dose. Significant changes greater than variability were determined for each performed measurement (expressed as mean percentage improvement with 95% CI). RESULTS: Significant effects (P < 0.05) were detected after 20 microg by X5 (18.5% CI 9.8-27.2) RF (11.1% CI 7.2-15.0) and sGaw (21.5% CI 10.1-32.9), and after 50 microg by R5 (16.7% CI 10.8-22.5) and Raw (19.7% CI 13.0-26.4). FEV1 was less sensitive, detecting significant bronchodilation at 100 microg (10.2% CI 7.4-12.9). CONCLUSIONS: We conclude that impulse oscillometry and plethysmography should be considered the preferred techniques for measuring bronchodilation in COPD clinical trials.
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Brônquios/fisiologia , Ensaios Clínicos como Assunto/métodos , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Albuterol/administração & dosagem , Broncodilatadores/administração & dosagem , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oscilometria/métodos , Pletismografia/métodos , Espirometria/métodosRESUMO
AIMS: We have compared the ability of plethysmography (sGaw), impulse oscillometry (IOS) and spirometry (FEV(1), MMEF) to detect bronchodilation in response to an anticholinergic. METHODS: IOS (R5, R20, X5, RF), sGaw and spirometry were measured in 12 healthy subjects and 12 asthmatics. Variability was assessed by performing two measurements, 30 min apart and the effect of increasing the number of readings for each sGaw measurement was also studied. Ipratropium bromide (IB) 10, 20, 100 and 200 microg was administered and the sensitivity of the methods compared by determining the lowest dose that caused changes greater than variability. RESULTS: In healthy subjects significant changes (P < or = 0.05) occurred at 10 microg for FEV(1) (mean [95% CI]; 1.3%[0.3-2.3]), R5 (mean [95% CI]; -7.9%, [-13.2-2.6]) and R20 (mean [95% CI], -6.4%, [-11.4-1.4]). No significant change was detected when the mean of 3 sGaw readings was used, but with 10 readings significant change was observed at 20 microg; (mean increase [95% CI] 15.2%[8.3-22.1]). In asthmatics significant changes (P < or = 0.05) occurred with IB 10 microg for sGaw (mean [95% CI] 25.6%[11.1-40.1]), R5 (mean [95% CI]-11.3%, [-15.5-7.2]), RF (mean [95% CI] 11.7%[6.1-16.3]), FEV(1) (mean [95% CI] 5.1%[2.6-7.7]) and MMEF (mean [95% CI] 12.3%[2.3-22.2]). CONCLUSION: IOS and spirometry are more sensitive than sGaw in healthy subjects, but the sensitivity of sGaw improved when the number of readings was increased. The most sensitive method for assessing bronchodilation in asthmatics was sGaw.
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Asma/tratamento farmacológico , Broncodilatadores/administração & dosagem , Ipratrópio/administração & dosagem , Adulto , Idoso , Asma/fisiopatologia , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pletismografia/métodos , Espirometria/métodosRESUMO
BACKGROUND: In response to the phasing out of chlorofluorocarbon (CFC) inhalers, a metered dose hydrofluoroalkane (HFA) formulation, Modulite (Chiesi Farmaceutici S.p.A, Parma, Italy), to be delivered with a pressurized metered dose inhaler (pMDI), has been developed. Modulite is a HFA formulation technology that has been designed to provide stable and uniform dose delivery of HFA-based formulations to enable an easy transition from CFC to HFA inhalers. OBJECTIVES: The aim of this study was to compare the bronchoprotective and bronchodilator effects of a single dose of 12 microg of formoterol from the HFA Modulite inhaler with the Foradil Aerolizer (dry powder inhaler, DPI) and the Foradil CFC inhalers (Novartis Health Consumer, Basel, Switzerland). METHODS: This was a double blind, double dummy, randomized, placebo-controlled, crossover study conducted in 38 subjects with mild to moderate asthma (mean forced expiratory volume in 1 s [FEV1] 87.5% predicted). The primary endpoint was methacholine challenge provocative dose required for 20% fall in the FEV1 (PD20) 90 min post dose. Bronchodilation was assessed with spirometry (FEV1, FVC, FEF25-75) and impulse oscillometry (resistance at 5 and 20 Hz, reactance at 5 Hz and resonant frequency) over the 90 min post dose. In a subset of 12 subjects formoterol plasma levels, serum potassium and glucose were determined up to 480 min post dose. RESULTS: The three formoterol formulations demonstrated significant (P < or = 0.05) improvements in bronchoprotection compared to placebo and non-inferiority of the HFA preparation compared to the CFC and DPI preparations was demonstrated. Geometric mean PD20 values were 0.51 mg with HFA, 0.62 mg with DPI, 0.62 mg with CFC and 0.2 mg with placebo. The log transformed mean differences in PD20 doubling dose between HFA and (a) DPI was -0.28 (95% CI -0.84-0.29, P = 0.57) (b) CFC was -0.28 (95% CI -0.84-0.28, P = 0.57) and (c) placebo was 1.38 (95% CI 0.82-1.94, P < 0.001). Serum potassium, glucose and formoterol plasma profiles were comparable for the CFC, HFA and DPI devices. CONCLUSION: Our findings of similar efficacy, pharmacokinetics and systemic effects of the HFA formoterol inhaler compared to the CFC and DPI preparations supports the potential use of this novel formulation in the treatment of asthma.
Assuntos
Propelentes de Aerossol , Broncodilatadores/administração & dosagem , Clorofluorcarbonetos , Etanolaminas/administração & dosagem , Hidrocarbonetos Fluorados , Administração por Inalação , Adulto , Estudos Cross-Over , Método Duplo-Cego , Feminino , Volume Expiratório Forçado/efeitos dos fármacos , Fumarato de Formoterol , Humanos , Masculino , Pessoa de Meia-Idade , Nebulizadores e Vaporizadores , Pós , Capacidade VitalRESUMO
AIM: To evaluate a modified urine collection pad (UCP) method for its ability to reduce heavy mixed growth bacterial contamination of UCP samples in young children with suspected urinary tract infection (UTI). METHOD: Febrile children under 2 years of age were randomised to two UCP METHODS: the same UCP kept in the nappy until urine was passed (single UCP group), or the UCP replaced with a fresh one every 30 minutes until urine was passed (replaced UCP group). In both groups a moisture sensitive audio alarm was used to signal passage of urine. RESULTS: Eighty children were enrolled and a satisfactory sample was obtained in 68 (37 in the single UCP group and 31 in the replaced UCP group). In 12 children (15%), collection failed, mainly because of faecal soiling of the pad. UTI occurred in three children (4%). In the remaining 65 samples, heavy mixed growth (> 10(5) organisms/ml) occurred in 1/31 (3%) in the replaced UCP group compared with 10/35 (29%) in the single UCP group (p = 0.008). There were no adverse effects from the use of the moisture sensitive audio alarm. CONCLUSION: Changing the UCP every 30 minutes almost eliminates heavy mixed growth contamination of UCP samples and substantially increases the proportion of UCP results that confidently exclude UTI. This represents a simple and clinically important improvement to the UCP method which is reliable for diagnosing and excluding UTI in young children still in nappies. It has potential for use in outpatient clinics, in the primary healthcare setting, or at home.
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Fraldas Infantis , Manejo de Espécimes/métodos , Infecções Urinárias/microbiologia , Urina , Bacteriúria/microbiologia , Feminino , Febre/microbiologia , Humanos , Lactente , Masculino , Fatores Sexuais , Fatores de Tempo , Infecções Urinárias/complicações , Infecções Urinárias/diagnósticoRESUMO
OBJECTIVES: To determine how many common clinical tests used in a respiratory medicine outpatient clinic are based on high quality evidence. DESIGN: Retrospective review of case notes. Record of first three tests for each patient. Diagnostic tests, tests used to assess existing condition, explicit trials of therapy were included. Literature search for supporting evidence and grading of best evidence for each test. SETTING: Inner city university teaching hospital in the United Kingdom. PARTICIPANTS: All new outpatients referred to a single respiratory medicine team over a period of three months. MAIN OUTCOME MEASURES: Proportion of tests supported by level 1a-1c evidence (scale developed by Centre for Evidence Based Medicine). RESULTS: Only half the tests that were used to make or exclude a diagnosis and a fifth of the tests used to assess a known condition were supported by level 1a-1c evidence. There was no evidence to support trials of therapy. CONCLUSIONS: A large proportion of clinical tests in respiratory medicine are not supported by level 1a-1c evidence. None of the therapeutic trials that were used were supported by evidence.
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Técnicas de Diagnóstico do Sistema Respiratório/normas , Pneumopatias/diagnóstico , Medicina Baseada em Evidências , Humanos , Estudos Retrospectivos , Saúde da População UrbanaRESUMO
Gain-of-function mutations in the gene encoding the receptor tyrosine kinase RET have been identified as the aetiological factor for multiple endocrine neoplasia type 2A (MEN2A). MEN2A is a dominantly-inherited cancer predisposition syndrome characterized by medullary thyroid carcinoma, a tumour of the calcitonin-producing thyroid C-cells. There are three isoforms of RET: RET9, RET43 and RET51, and although in vitro evidence suggests they vary in cellular transformation activities, little is known about their function in tumorigenesis in vivo. To address this, we used RET51 cDNA to construct mice in which the most frequent MEN2A mutation, Cys-634-Arg, was expressed under the control of the human calcitonin promoter (CT-2A mice). These mice developed C-cell tumours resembling human MTC and follicular tumours resembling human papillary thyroid carcinoma (PTC) depending on the founder line examined. One founder line developed compound MTC/PTC at low frequency (8%) and pancreatic cystadenocarcinoma. CT-2A mice also displayed a developmental defect in thyroid follicular structure, in which much of the thyroid was occupied by large irregular cystic follicles thought to be derived from the ultimobranchial body, a developmental precursor of the thyroid gland. The CT-2A mice will provide a suitable model to further study the effects of the MEN 2A RET mutation in vivo.
Assuntos
Carcinoma Medular/genética , Carcinoma Papilar/genética , Proteínas de Drosophila , Neoplasia Endócrina Múltipla Tipo 2a/genética , Isoformas de Proteínas/genética , Proteínas Proto-Oncogênicas/genética , Receptores Proteína Tirosina Quinases/genética , Neoplasias da Glândula Tireoide/genética , Substituição de Aminoácidos , Animais , Calcitonina/genética , Carcinoma Medular/patologia , Carcinoma Papilar/patologia , Transformação Celular Neoplásica/genética , Cistadenocarcinoma/genética , DNA Complementar/genética , Regulação Neoplásica da Expressão Gênica , Genes Sintéticos , Camundongos , Camundongos Transgênicos , Neoplasia Endócrina Múltipla Tipo 2a/patologia , Mutação de Sentido Incorreto , Neoplasias Pancreáticas/genética , Regiões Promotoras Genéticas , Isoformas de Proteínas/fisiologia , Proteínas Proto-Oncogênicas/fisiologia , Proteínas Proto-Oncogênicas c-ret , Splicing de RNA , Receptores Proteína Tirosina Quinases/fisiologia , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/fisiologia , Neoplasias da Glândula Tireoide/patologia , TransgenesRESUMO
The aim was to produce a radiolabelled fibre suitable for long-term carcinogenesis studies. To this end, we have successfully synthesised erionite fibres by a method adapted to incorporate (57)Co into the crystal framework. Morphologically the fibres are straight, of median length 2.5 microm, with 11% of fibres > 8 microm long, and median width 0.32 microm. These values are comparable to natural Oregon erionite. Autoradiography confirmed that the (57)Co was associated with the fibres themselves. The stability of the radiolabel in vivo was examined by instilling 1 mg of synthetic erionite into the lungs of F-344 rats. About half of the thoracic content of (57)Co was cleared in the first week, and over the following 5 weeks the remainder was cleared slowly with a half-time of 120 days. After 6 weeks the urinary excretion of (57)Co was only 0.054% of the initial lung content per day. This represented fibre dissolution plus any leaching of (57)Co from the fibres. It can be concluded that the (57)Co is bound into the erionite fibres with sufficient stability in vivo for studying their effects in relation to translocation to the pleura.
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Zeolitas/síntese química , Animais , Autorradiografia , Fibras Minerais , Ratos , Ratos Endogâmicos F344RESUMO
Our aim was to evaluate the technique, results and complications in 126 women with pulsion enterocoele treated with the combined abdominoperineal repair. Mean follow-up was 25 months with a range of 0-83 months. Operative morbidity included bladder trauma (0.7%), bowel injury (3.1%), wound breakdown (0.7%), infection (10%), pulmonary embolus (0.7%) and blood transfusion (40%). Longterm complications included prolonged urinary retention (11%), incisional hernia (4.7%) and constipation (40.4%). 92.4% of women were cured.
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Hérnia Ventral/cirurgia , Histerectomia/efeitos adversos , Complicações Pós-Operatórias/diagnóstico , Telas Cirúrgicas , Procedimentos Cirúrgicos Operatórios/métodos , Abdome/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Austrália , Feminino , Seguimentos , Hérnia Ventral/etiologia , Humanos , Histerectomia/métodos , Pessoa de Meia-Idade , Períneo/cirurgia , Complicações Pós-Operatórias/mortalidade , Sistema de Registros , Medição de Risco , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Procedimentos Cirúrgicos Operatórios/mortalidade , Taxa de Sobrevida , Resultado do TratamentoRESUMO
Asbestos fibres have been shown to stimulate the mitogen-activated protein kinase signalling cascade in rat pleural mesothelial (RPM) cells after autophosphorylation of the epidermal growth factor receptor (EGFR). We examined if mineral fibres with known carcinogenicity can be discriminated from materials with less or no carcinogenicity by their ability to up-regulate expression of EGFR protein in RPM cells in vitro. Crocidolite and erionite, two fibrous preparations with marked potential to induce mesothelioma, were associated with increases in EGFR protein expression over sham controls, whereas chrysotile asbestos and milled (non-fibrous) crocidolite did not. Intense patterns of EGFR protein expression were linked to RPM cells phagocytosing long fibres. To determine the role of EGFR expression in these cells, we assessed cell proliferation using an antibody against proliferating cell nuclear antigen (PCNA) in combination with an antibody against EGFR. In these co-localization studies, cells showed intense staining for EGFR protein 24 h before being PCNA positive at 48 h. These results suggest that carcinogenic fibres induce EGFR and initiate cell signalling cascades in mesothelial cells, leading to cell proliferation and carcinogenesis.
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Asbesto Crocidolita/toxicidade , Asbestos Serpentinas/toxicidade , Carcinógenos/toxicidade , Células Epiteliais/efeitos dos fármacos , Receptores ErbB/genética , Pleura/citologia , Zeolitas/toxicidade , Animais , Células Cultivadas , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Receptores ErbB/metabolismo , Masculino , Ratos , Ratos Endogâmicos F344 , Regulação para CimaRESUMO
Asbestos has been shown to stimulate the mitogen-activated protein kinase signaling cascade after autophosphoryiation of the epidermal growth factor recptor (EGF-R), an event important in regulating the response of cells to extracellular signals. In studies reported here, we have examined whether mineral fibers with known carcinogenicity can be discriminated from nonpathogenic fibers by their ability to upregulate expression of EGF-R protein in mesothelial cells. Crocidolite and erionite, two fibrous preparations known to induce mesothelioma, increased expression of EGF-R protein in a time- and dose-dependent manner, whereas milled (nonfibrous) crocidolite and chrysotile asbestos, two preparations with much less or no ability to induce mesothelioma, did not. Intense patterns of EGF-R protein expression were linked to mesothelial cells phagocytosing long fibers as observed by phase-contrast microscopy. To determine the importance of EGF-R expression in these cells, we assessed downstream signaling events in rat pleural mesothelial (RPM) cells by looking at the induction of activator protein-1 (AP-I), a transcription factor that controls the transition to S phase in the cell cycle, leading to cell proliferation. Crocidolite induced AP-I in RPM cells in a dose-dependent manner, and this induction of AP-I in RPM cells was inhibited by coincubation with tyrphostin AG 1478, a potent inhibitor of the EGF-R. To examine the mechanism of induction of EGF-R in RPM cells by asbestos, RPM cells were treated with crocidolite in the presence and absence of the antioxidant N-acetylcysteine (NAC). Reduced glutathione (GSH) was examined as a marker of oxidative stress and the expression of EGF-R protein was measured. Crocidolite asbestos caused a dose-dependent depletion of GSH in RPM cells, and the presence of NAC ameliorated the expression of EGF-R protein by crocidolite. Our data suggest that carcinogenic fibers induce EGF-R via a mechanism involving oxidative stress initiating cell signaling cascades in mesothelial cells leading to cell proliferation and carcinogenesis.
RESUMO
We investigated the suppressive effects of rolipram, RP 73401 (piclamilast), and other structurally diverse inhibitors of adenosine 3'5'-cyclic monophosphate (cAMP)-specific phosphodiesterase (PDE4) on anti-CD3-stimulated interleukin (IL)-4 and IL-5 generation by splenocytes from BALB/c mice infected with Mesocestoides (M) corti. RP 73401 (IC40: 0.011 +/- 0.004 microM) was a very potent inhibitor of anti-CD3-induced IL-4 release, being approximately 40-fold more potent than (+/-)-rolipram (IC40: 0.43 +/- 0.09 microM). A maximal inhibition of 60-70% of the response was achieved at the top concentrations of RP 73401 (1 microM) and rolipram (100 microM). These PDE inhibitors also suppressed IL-5 generation over the same concentration ranges, but the maximal suppression achieved was only 30-40%. R-(-)-rolipram (IC40: 0.39 +/- 0.09 microM) was approximately 6-fold more potent than S-(+)- rolipram (IC40: 2.6 +/- 0.95 microM) in inhibiting IL-4 release. A close correlation (r2 = 0.82) was observed between suppression of IL-4 release by PDE inhibitors and inhibition of CTLL cell PDE4, a form against which R-(-)-rolipram displayed relatively weak inhibitory potency. A poorer correlation (r2 = 0.26) was observed between suppression of IL-4 release and affinities of cAMP PDE inhibitors for the high-affinity rolipram binding site in mouse brain membranes. The cGMP-inhibited PDE (PDE3) inhibitor, siguazodan, had little or no effect (IC40 > 100 microM) on anti-CD3-stimulated release of either IL-4 or IL-5 and did not significantly enhance the inhibitory action of RP 73401 on the release of either of these cytokines. Finally, RP 73401 (IC50: 0.41 +/- 0.19 nM) inhibited anti-CD3-stimulated DNA synthesis in splenocyte preparations from M. corti-infected mice and siguazodan (10 microM) had no effect on this response, either alone or in combination with the PDE4 inhibitor. The results show that PDE4 inhibitors suppress the release of Th2 cytokines from anti-CD3-stimulated murine spenocytes and that this effect is correlated with inhibition of a low-affinity PDE4 form.