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1.
Regul Toxicol Pharmacol ; 137: 105284, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36402242

RESUMO

Mineral oils (food grade white oil or liquid paraffin) have historically been safely used in a number of sensitive end-uses, including pharmaceutical, cosmetic and food. Recent concern that certain mineral hydrocarbons (branched and cyclo-alkanes) may accumulate in human tissues has prevented European Food Safety Authority (EFSA) from deriving guidance values for food exposures. Analysis of human and animal tissue indicate that an unresolved cloud of mostly highly branched alkanes and alkylated cycloalkanes within the C20-C35 range is consistently present in all tissues. This critical review thoroughly assesses the retention of "mineral oil saturated hydrocarbons" (MOSH) in human and animal tissues and evaluates if the presence of MOSH is considered adverse and appropriate to use for risk assessment, generation of guidance values for food exposure and/or generation of derivation of health-based guidance values. An adversity framework was utilized to perform an in-depth weight of the evidence analysis, and it was concluded that mere presence of MOSH does not translate to hazard identification, and is not considered adverse. In light of this conclusion, it would not be appropriate to utilize this endpoint as the point of departure to calculate a health guidance value.


Assuntos
Cosméticos , Óleo Mineral , Animais , Humanos , Hidrocarbonetos , Inocuidade dos Alimentos , Alcanos , Contaminação de Alimentos/análise
2.
Encephale ; 48(4): 430-435, 2022 Aug.
Artigo em Francês | MEDLINE | ID: mdl-34238567

RESUMO

INTRODUCTION: Management of anorexia nervosa is difficult and few treatments have shown their effectiveness, justifying the exploration of new therapeutic approaches. Available evidence suggests an interest of psychoeducational groups in a significant number of psychiatric disorders. In patients suffering from anorexia, to date there are few groups or interventions available. We aimed to assess the feasibility and acceptability of a psycho-educational program promoting information about the disease and presenting techniques that can help to cope with anorexia and the functional impact it causes. The exploratory secondary objectives were to evaluate if such a group is associated with clinical improvement. METHOD: Twenty-seven patients suffering from anorexia nervosa, in three groups, received eight weekly interventions in addition to their usual care. The study was open-label and non-randomized. Patients were assessed three times (baseline, at the end of the group and three months later). The assessments were both qualitative (Eating Disorder Examination questionnaire, The Anorexia Nervosa Stage of Change Questionnaire, the Eating Disorders Quality of Life questionnaire, Work and Social Adjustment Scale) and qualitative. RESULTS: Seventy-eight percent of participants attended more than 75 % of the sessions. Seventy percent of participants found the group useful, and 95 % said it helped them improve their knowledge of the disease and its consequences. The average BMI of participants changed significantly with an average increase of 2.5kg between baseline and the three month assessment. There was an improvement of the eating disorders features in EDE-Q for the total score and for all subscores. The improvement in the total score was significant at the end of the group sessions, while the improvement in the sub scores became significant at three months. There was also a significant mood improvement at the end of the group. Finally, there was a significant improvement in daily functioning with a decrease in Work and Social Adjustment Scale scores and an improvement in quality of life. On qualitative assessment, patients were satisfied with the care proposal. They were able to appreciate the support and sharing of experience provided by the group formula. Most of them reported changes in their daily lives, either in their relationship to care and illness, or in their relationships with their loved ones, their leisure/work, their mood or their eating behavior. CONCLUSION: Both qualitative and quantitative results suggest that this group psychoeducation program is feasible and well accepted by patients in addition to usual management. Although the methodology does not allow any conclusions, the clinical improvements observed during the group are encouraging with regard to the safety of this type of intervention and its possible effectiveness and argue for a controlled study.


Assuntos
Anorexia Nervosa , Anorexia , Anorexia Nervosa/psicologia , Anorexia Nervosa/terapia , Estudos de Viabilidade , Humanos , Qualidade de Vida , Inquéritos e Questionários
3.
Transfus Clin Biol ; 28(2): 191-193, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33516887

RESUMO

We report the case of a 43-years-old Turkish man with acquired deficiency of factor V (FV) diagnosed in a usual screening before a (recto) colonoscopy. In the biologic explorations, activated partial prothrombin time (APTT) was abnormally high and prothrombin time (PT) was low 18IU/dL with no anticoagulant drugs (the PT was normal 6 months ago). The controlled level of factor V was 3IU/dL with FV antibodies (9 Bethesda Units/mL). This patient had a previous history of primary sclerosing cholangitis (2000) and ulcero haemorrhagic rectocolitis (2002) and a fortuitous biological Biermer's disease was revealed. Corticosteroids were prescribed at 1mg/kg/day with decreasing during 6 months, patient had gradual regression of the caused bleeding and FV became greater than 90%, F V antibodies decreased to less than 0.7 Bethesda Units/mL. This case illustrates the presence of FV inhibitor in an autoimmune gastrointestinal context with regression of clinical (caused) signs and antibodies with corticosteroids.


Assuntos
Colangite Esclerosante , Proctocolite , Adulto , Testes de Coagulação Sanguínea , Colangite Esclerosante/complicações , Colangite Esclerosante/tratamento farmacológico , Fator V , Humanos , Masculino , Esteroides
4.
J Hazard Mater ; 389: 122132, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32062395

RESUMO

The depletion of traditional oil fields is driving the oil & gas industry to explore new exploitation sites previously considered as unprofitable. Deep-sea oil fields represent one of these new areas of exploitation. Well drilling during exploration and production operations generate large quantities of drilling waste whose biological impact on the deep-sea floor remains largely unknown. Because of the harsh abiotic factors characterizing this environment, the evaluation of this impact remains challenging. High hydrostatic pressure is the prominent factor which will affect in-situ biological processes. This review will examine the feedback on the various strategies used to evaluate the biological impact of deep-sea drilling waste deposition as well as the current technological limitations. Given the complexity of this issue, a good perspective strategy would be to trend towards the research and development of more relevant bioassays, especially considering the crucial factor of hydrostatic pressure.


Assuntos
Organismos Aquáticos , Ecossistema , Monitoramento Ambiental/métodos , Sedimentos Geológicos , Resíduos Industriais/efeitos adversos , Poluição da Água/efeitos adversos , Animais , Campos de Petróleo e Gás , Indústria de Petróleo e Gás/legislação & jurisprudência , Indústria de Petróleo e Gás/métodos
5.
Transfus Clin Biol ; 26(4): 356-358, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31262628

RESUMO

We report the case of a French woman with acquired von Willebrand syndrome who presents recurrent subarachnoid and intra-cerebral hemorrhage since 2012. She had no family or personal bleeding history. In the biologic explorations, APTT was abnormally high with no anticoagulant drugs (it was normal, historically). Two monoclonal IgG and IgM kappa proteins were detected without any lymphoproliferative disorder. Intravenous infusion of immunoglobulin is very effective in AVWS with immunoglobulin G monoclonal gammapathie of undetermined significance. We had a satisfactory correction of coagulation factors for about 30 days. The exploration of APTT is surely essential for the diagnosis and treatment.


Assuntos
Hemorragia Cerebral/etiologia , Gamopatia Monoclonal de Significância Indeterminada/imunologia , Doenças de von Willebrand/diagnóstico , Idoso , Autoanticorpos/imunologia , Testes de Coagulação Sanguínea , Hemorragia Cerebral/diagnóstico por imagem , Hemorragia Cerebral/prevenção & controle , Epistaxe/etiologia , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Cadeias kappa de Imunoglobulina/sangue , Imunoglobulinas Intravenosas/uso terapêutico , Imageamento por Ressonância Magnética , Gamopatia Monoclonal de Significância Indeterminada/complicações , Neuroimagem , Paraproteínas/análise , Recidiva , Hemorragia Subaracnóidea/diagnóstico por imagem , Hemorragia Subaracnóidea/etiologia , Doenças de von Willebrand/etiologia , Doenças de von Willebrand/imunologia , Doenças de von Willebrand/terapia , Fator de von Willebrand/uso terapêutico
6.
Aquat Toxicol ; 178: 197-208, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27522032

RESUMO

Human alteration of marine ecosystems is substantial and growing. Yet, no adequate methodology exists that provides reliable predictions of how environmental degradation will affect these ecosystems at a relevant level of biological organization. The primary objective of this study was to develop a methodology to evaluate a fish's capacity to face a well-established environmental challenge, an exposure to chemically dispersed oil, and characterize the long-term consequences. Therefore, we applied high-throughput, non-lethal challenge tests to assess hypoxia tolerance, temperature susceptibility and maximal swimming speed as proxies for a fish's functional integrity. These whole animal challenge tests were implemented before (1 month) and after (1 month) juvenile European sea bass (Dicentrarchus labrax) had been acutely exposed (48h) to a mixture containing 0.08gL(-1) of weathered Arabian light crude oil plus 4% dispersant (Corexit© EC9500A), a realistic exposure concentration during an oil spill. In addition, experimental populations were then transferred into semi-natural tidal mesocosm ponds and correlates of Darwinian fitness (growth and survival) were monitored over a period of 4 months. Our results revealed that fish acutely exposed to chemically dispersed oil remained impaired in terms of their hypoxia tolerance and swimming performance, but not in temperature susceptibility for 1 month post-exposure. Nevertheless, these functional impairments had no subsequent ecological consequences under mildly selective environmental conditions since growth and survival were not impacted during the mesocosm pond study. Furthermore, the earlier effects on fish performance were presumably temporary because re-testing the fish 10 months post-exposure revealed no significant residual effects on hypoxia tolerance, temperature susceptibility and maximal swimming speed. We propose that the functional proxies and correlates of Darwinian fitness used here provide a useful assessment tool for fish health in the marine environment.


Assuntos
Bass/fisiologia , Comportamento Animal/efeitos dos fármacos , Petróleo/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Bass/crescimento & desenvolvimento , Ecossistema , Hipóxia , Natação/fisiologia , Temperatura
7.
Prog Brain Res ; 227: 257-76, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27339015

RESUMO

In this review, we provide an overview of how age-related changes in executive control influence aging effects in arithmetic processing. More specifically, we consider the role of executive control in strategic variations with age during arithmetic problem solving. Previous studies found that age-related differences in arithmetic performance are associated with strategic variations. That is, when they accomplish arithmetic problem-solving tasks, older adults use fewer strategies than young adults, use strategies in different proportions, and select and execute strategies less efficiently. Here, we review recent evidence, suggesting that age-related changes in inhibition, cognitive flexibility, and working memory processes underlie age-related changes in strategic variations during arithmetic problem solving. We discuss both behavioral and neural mechanisms underlying age-related changes in these executive control processes.


Assuntos
Envelhecimento/fisiologia , Função Executiva/fisiologia , Matemática , Resolução de Problemas/fisiologia , Humanos , Inibição Psicológica
8.
Ann Dermatol Venereol ; 141(12): 777-81, 2014 Dec.
Artigo em Francês | MEDLINE | ID: mdl-25433931

RESUMO

BACKGROUND: Sezary syndrome (SS) presents clinically as erythroderma, which may be pigmented, and pruritic, associated with peripheral lymphadenopathies. Erythroderma may also occur in a broad range of reactive and malignant conditions including T-cell prolymphocytic leukemia (T-PLL). We report a case initially diagnosed as SS but ultimately diagnosed as T-PLL based upon skin involvement. CASE REPORT: A 70-year-old man was referred by his hematologist for management of SS. Physical examination revealed lymphadenopathies and mild diffuse erythema without infiltration. His WBC count was elevated at 8.3 G/L. A peripheral blood smear showed Sezary-like cells. Flow cytometry of peripheral blood revealed prolymphocytic T-cells staining positively for CD2, CD3, CD4 and CD7. Cytogenetic studies showed chromosomal abnormalities in terms of number and structure with missing chromosomes 6 and13, as well as deletion of chromosome 17. Finally, a diagnosis of T-PLL was made. Pentostatin was initiated pending treatment with alemtuzumab, but the patient's overall condition deteriorated rapidly and he died 10 days later. DISCUSSION: Diagnosis of LPLT is based upon a number of factors. In the case presented herein, the clinically atypical nature of the skin lesions prompted the dermatologist to review the diagnosis. The morphology of the circulating T-lymphocytes and their immunologic and phenotypic characteristics finally ruled out the diagnosis of Sezary syndrome, while their association with compatible cytogenetic anomalies enabled a diagnosis of prolymphocytic leukemia to be made instead. CONCLUSION: Prolymphocytic leukemia involves complex differential diagnosis with regard to Sezary syndrome, posing potential pitfalls for hematologists and dermatologists.


Assuntos
Erros de Diagnóstico , Leucemia Prolinfocítica de Células T/diagnóstico , Neoplasias Cutâneas/diagnóstico , Linfócitos T/patologia , Adenocarcinoma/terapia , Idoso , Antimetabólitos Antineoplásicos/uso terapêutico , Capecitabina/uso terapêutico , Deleção Cromossômica , Terapia Combinada , Diagnóstico Tardio , Evolução Fatal , Humanos , Imunofenotipagem , Leucemia Prolinfocítica de Células T/tratamento farmacológico , Leucemia Prolinfocítica de Células T/genética , Leucemia Prolinfocítica de Células T/patologia , Masculino , Segunda Neoplasia Primária , Pentostatina/uso terapêutico , Neoplasias Retais/terapia , Síndrome de Sézary/diagnóstico , Neoplasias Cutâneas/tratamento farmacológico , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia
9.
Acta Psychol (Amst) ; 137(3): 335-44, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21549334

RESUMO

Young and older adults differ in how many strategies they use to accomplish cognitive tasks. They also differ in how often they select the best strategy on each problem. Two experiments were run to determine whether two executive functions-inhibition and shifting capacities-mediate age-related differences in strategy repertoire and in strategy selection. Both experiments were run in arithmetic problem solving. In Experiment 1, young and older adults' strategy repertoire was assessed on a problem-by-problem basis while participants solved two-digit addition problems (e.g., 42+76). In Experiment 2, young and older participants had to select the best strategy on each problem to find estimates of two-digit multiplication problems (e.g., 43×72). In both experiments, individuals' inhibition and shifting capacities were assessed with the Trail Making Test and the Stroop Test. The main results showed that (a) older adults used a smaller strategy repertoire (Expt. 1) and selected the best strategy on each problem less frequently (Expt. 2) than young adults, (b) inhibition and shifting capacities mediated age-related differences in strategy repertoire and strategy selection, and unique age effects were no longer significant in strategy repertoire but were still significant in strategy selection after statistical control of inhibition and shifting capacities. We discuss important implications of these findings to further our understanding of strategic variations during cognitive aging.


Assuntos
Envelhecimento/psicologia , Cognição/fisiologia , Função Executiva/fisiologia , Inibição Psicológica , Resolução de Problemas/fisiologia , Adulto , Fatores Etários , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
10.
Fetal Diagn Ther ; 22(1): 23-8, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17003551

RESUMO

Bruck syndrome is characterized by the association of arthrogryposis and osteogenesis imperfecta. It is a distinct autosomal recessive disorder associated with normal collagen I. The main features are osteoporosis, long bone bowing and scoliosis due to vertebral deformities and congenital joint contractures. We describe a French girl who was born with ankle and wrist contractures (second antenatal discovery).


Assuntos
Artrogripose/diagnóstico , Osteogênese Imperfeita/diagnóstico , Diagnóstico Pré-Natal , Adulto , Feminino , Humanos , Recém-Nascido , Gravidez , Síndrome
11.
Bone Marrow Transplant ; 38(6): 427-32, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16878146

RESUMO

Short stature and gonad failure can be a side effect of total body irradiation (TBI). The purpose of the study was to evaluate the factors influencing final height and gonad function after TBI. Fifty young adults given TBI during childhood were included. Twenty-seven had been treated with growth hormone (GH). Those given single 10 Grays (Gy) or fractionated 12 Gy TBI had similar characteristics, GH peaks, final heights and gonad function. After the end of GH treatment, 11/20 patients evaluated had GH peak >10 microg/l. Final height was <-2s.d. in 29 (58%). The height loss between TBI and final height (2.4+/-1.1 s.d.) was greater in those who were younger when irradiated (P<0.0001). When the GH-treated and -untreated patients were analyzed separately, this loss was correlated with the age at TBI at 4-8 years for the GH-treated and at 6-8 years for the untreated. Boys showed negative correlations between testicular volume and plasma follicle-stimulating hormone (FSH, P=0.0008) and between plasma FSH and inhibin B (P=0.005) concentrations. We concluded that the indications for GH treatment should be mainly based on the age at irradiation, taking into account the GH peak. The plasma FSH and inhibin B concentrations may predict sperm function.


Assuntos
Estatura/efeitos da radiação , Transtornos do Crescimento/sangue , Testículo/crescimento & desenvolvimento , Condicionamento Pré-Transplante/efeitos adversos , Irradiação Corporal Total/efeitos adversos , Adolescente , Fatores Etários , Criança , Pré-Escolar , Feminino , Hormônio Foliculoestimulante/sangue , Seguimentos , Transtornos do Crescimento/tratamento farmacológico , Transtornos do Crescimento/etiologia , Transtornos do Crescimento/patologia , Neoplasias Hematológicas/complicações , Neoplasias Hematológicas/patologia , Neoplasias Hematológicas/terapia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Hormônio do Crescimento Humano/administração & dosagem , Hormônio do Crescimento Humano/sangue , Humanos , Inibinas/sangue , Masculino , Tamanho do Órgão/efeitos da radiação , Ovário/crescimento & desenvolvimento , Ovário/patologia , Ovário/efeitos da radiação , Dosagem Radioterapêutica , Fatores Sexuais , Espermatozoides/metabolismo , Espermatozoides/patologia , Testículo/patologia , Testículo/efeitos da radiação
12.
Water Sci Technol ; 52(1-2): 457-64, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16180464

RESUMO

The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.


Assuntos
Reatores Biológicos , Eliminação de Resíduos Líquidos/métodos , Automação , Bactérias Anaeróbias/metabolismo , Resíduos Industriais , Internet , Software , Análise de Sistemas
13.
Fetal Diagn Ther ; 20(4): 301-5, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15980645

RESUMO

Binder syndrome (BS) or maxillo-nasal dysplasia is an uncommon developmental anomaly affecting primarily the anterior part of the maxilla and nasal complex. The characteristic findings are a failure of development in the premaxillary area with associated deformities of the nasal skeleton and the overlying soft tissues. Affected individuals typically have an unusually flat, underdeveloped midface (midfacial hypoplasia), with an abnormally short nose and flat nasal bridge, underdeveloped upper jaw, relatively protruding lower jaw and/or a 'reverse overbite' (or class III malocclusion). A case of BS was diagnosed at 24 weeks of gestation using two- and three-dimensional ultrasound. The first sign was an isolated flattened fetal nose in the mid-sagittal plane. Further ultrasound imaging showed the absence of the naso-frontal angle, giving impression of flat forehead and small fetal nose. We discuss about this entity.


Assuntos
Ossos Faciais/anormalidades , Anormalidades Maxilofaciais/diagnóstico por imagem , Nariz/anormalidades , Ultrassonografia Pré-Natal , Adulto , Feminino , Humanos , Recém-Nascido , Gravidez
14.
Fetal Diagn Ther ; 20(3): 197-202, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15824498

RESUMO

Prenatal diagnosis performed by ultrasound scan is now a routine part of antenatal care in France. A case of congenital short femur in an otherwise healthy infant is described. Antenatal diagnosis was made at 18 weeks of gestation and ultrasonic follow-up was performed. The right femur was shorter than the left. Further sonographic exploration demonstrated unilateral femoral hypoplasia without another anomaly. In this case, the occurrence of congenital short femur was sporadic. The diagnosis was confirmed after delivery. Prenatal sonographic features, differential diagnosis, prognosis and management are discussed. This case illustrates the importance of ultrasound as an early detector of certain congenital anomalies and as a useful tool in their follow-up.


Assuntos
Fêmur/anormalidades , Fêmur/diagnóstico por imagem , Adulto , Feminino , Fêmur/embriologia , Idade Gestacional , Humanos , Recém-Nascido , Deformidades Congênitas dos Membros/diagnóstico por imagem , Deformidades Congênitas dos Membros/patologia , Gravidez , Radiografia , Ultrassonografia Pré-Natal
15.
J Gynecol Obstet Biol Reprod (Paris) ; 33(4): 325-9, 2004 Jun.
Artigo em Francês | MEDLINE | ID: mdl-15170429

RESUMO

Prognosis of subependymal pseudocyst is poor when associated with other anomalies. They can be caused by infectious, vascular, chromosomal or metabolic disorders but are rarely described in the antenatal period. We report the prenatal diagnosis of subependymal pseudocyst by MRI after prenatal detection of isolated ventriculomegaly at 23 weeks gestation. The karyotype was normal. The diagnostic of Zellweger syndrome was suspected and was confirmed after birth by metabolic studies. Metabolic studies with culture of chorionic villus cell is indicated for subsequent pregnancies.


Assuntos
Diagnóstico Pré-Natal , Síndrome de Zellweger/diagnóstico , Adulto , Ventrículos Cerebrais/diagnóstico por imagem , Cistos/diagnóstico , Epêndima , Feminino , Idade Gestacional , Humanos , Imageamento por Ressonância Magnética , Gravidez , Ultrassonografia Pré-Natal
16.
Ann Biol Clin (Paris) ; 61(4): 463-5, 2003.
Artigo em Francês | MEDLINE | ID: mdl-12915357

RESUMO

We describe an abnormal chromatin clumping phenomenon (ACC) with nuclear loss of segmentation on circulating neutrophils in three patients receiving mycophenolate mofetil (Cellcept). It is worth being aware of this rare adverse event because of its unknown origin and of its possible clinical consequences.


Assuntos
Montagem e Desmontagem da Cromatina/efeitos dos fármacos , Imunossupressores/efeitos adversos , Ácido Micofenólico/análogos & derivados , Ácido Micofenólico/efeitos adversos , Neutrófilos/patologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Síndrome
17.
Dev Biol ; 252(2): 151-69, 2002 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-12482707

RESUMO

Ascidians are simple invertebrate chordates whose lineage diverged from that of vertebrates at the base of the chordate tree. Their larvae display a typical chordate body plan, but are composed of a remarkably small number of cells. Ascidians develop with an invariant cell lineage, and their embryos can be easily experimentally manipulated during the cleavage stages. Their larval nervous system is organised in a similar way as in vertebrates but is composed of less than 130 neurones and around 230 glial cells. This remarkable simplicity offers an opportunity to understand, at the cellular and molecular levels, the ontogeny and function of each neural cell. Here, we first review the organisation of the ascidian nervous system and its lineage. We then focus on the current understanding of the processes of neural specification and patterning before and during gastrulation. We discuss these advances in the context of what is currently known in vertebrates.


Assuntos
Sistema Nervoso Central/embriologia , Urocordados/embriologia , Animais , Evolução Biológica
18.
Mech Dev ; 108(1-2): 71-9, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11578862

RESUMO

In Xenopus, the Spemann organiser is defined as a dorsal territory in the early gastrula that initiates development of the embryonic axis. It has been shown that the early zygotic transcription factor Siamois is essential for Spemann's organiser formation. By the onset of gastrulation, the organiser is patterned into a vegetal head organiser, which induces anterior structures upon transplantation, and a more animal trunk organiser, which induces a posterior neuraxis. However, it is unclear when these distinct organiser domains are initially specified. To shed light on this question, we analysed the temporal activity of Siamois, as this factor induces both head and trunk development, when ectopically expressed via mRNA injection. In this study, we expressed Siamois ectopically at different time points and analysed the extent of axial development. Using a hormone-inducible version of Siamois, we found evidence for a tight window of competence during which ventral cells can respond to Siamois by commencing both the head and the trunk genetic programmes. The competence to form Spemann's organiser was lost 2 h before gastrulation, although partial axis formation could still occur following delayed activation of Siamois. We demonstrate that this late response to Siamois involves a new role for this gene, which can indirectly repress ventral gene expression, in the absence of known organiser genes.


Assuntos
Blastocisto/citologia , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/fisiologia , Organizadores Embrionários/embriologia , Xenopus/embriologia , Xenopus/genética , Animais , Padronização Corporal/genética , Padronização Corporal/fisiologia , Gástrula/citologia , Regulação da Expressão Gênica no Desenvolvimento , Genes Homeobox , Hibridização In Situ , Regiões Promotoras Genéticas , RNA Mensageiro/administração & dosagem , RNA Mensageiro/genética , Proteínas de Xenopus
19.
J Exp Psychol Appl ; 7(3): 195-206, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11676098

RESUMO

Younger and older adults were taught new strategies for converting amounts presented in French francs into euros or amounts presented in euros into French francs. The choice/no-choice method was used to obtain information on how often each newly learned strategy was used as well as information on the speed and accuracy of strategies. The results showed that both younger and older participants used the new conversion strategies unequally often and had strategy preferences that were justified by the relative ease of execution of each strategy. We discuss numerous practical applications of the present findings, as they suggest that one can help younger and older people by teaching them the add-half and divide-three strategies for the French-franc-euro conversions, that no specific strategies should be taught to older people, and that newly taught strategies are more efficient than those people use spontaneously.


Assuntos
Envelhecimento/psicologia , Economia , Resolução de Problemas , Comportamento Verbal , Adolescente , Adulto , Idoso , Feminino , França , Humanos , Masculino , Pessoa de Meia-Idade
20.
Development ; 128(19): 3783-93, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11585804

RESUMO

The Xenopus trunk organiser recruits neighbouring tissues into secondary trunk axial and paraxial structures and itself differentiates into notochord. The inductive properties of the trunk organiser are thought to be mediated by the secretion of bone morphogenetic protein (BMP) antagonists. Ectopic repression of BMP signals on the ventral side is sufficient to mimic the inductive properties of the trunk organiser. Resultant secondary trunks contain somite and neural tube, but no notochord. We show that inhibition of BMP signalling is sufficient for the initiation of the trunk organiser genetic programme at the onset of gastrulation. During late gastrulation, however, this programme is lost, due to an invasion of secreted Wnts from neighbouring tissues. Maintenance of this programme requires co-repression of BMP and Wnt signalling within the presumptive notochord region. To shed light on the molecular cascade that leads to the repression of the Wnt pathway, we looked for individual organiser genes whose overexpression could complement the inhibition of BMP signalling to promote notochord formation in the secondary trunks. Two genes, gsc and Xnot, were thus identified and shown to act in different ways. Xnot acts as a transcriptional repressor within the mesodermal region. Gsc acts in deeper vegetal cells, where it regulates Frzb expression to maintain Xnot expression in the neighbouring notochord territory. These results suggest that, during gastrulation, the necessary repression of Wnt/beta-catenin signalling in notochord precursors is achieved by the action of secreted inhibitors, such as Frzb, emitted by gsc-expressing dorsal vegetal cells.


Assuntos
Proteínas de Homeodomínio/genética , Peptídeos e Proteínas de Sinalização Intercelular , Notocorda/embriologia , Proteínas Proto-Oncogênicas/genética , Transativadores/genética , Proteínas de Xenopus , Xenopus laevis/embriologia , Proteínas de Peixe-Zebra , Sequência de Aminoácidos , Animais , Blastômeros , Proteínas Morfogenéticas Ósseas/genética , Proteínas Morfogenéticas Ósseas/imunologia , Proteínas Morfogenéticas Ósseas/metabolismo , Proteínas do Citoesqueleto/metabolismo , Embrião não Mamífero , Feminino , Fatores de Transcrição Forkhead , Receptores Frizzled , Gástrula , Regulação da Expressão Gênica no Desenvolvimento , Glicoproteínas/genética , Glicoproteínas/metabolismo , Proteína Goosecoid , Proteínas de Homeodomínio/metabolismo , Proteínas com Homeodomínio LIM , Mesoderma , Dados de Sequência Molecular , Proteínas , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transdução de Sinais , Transativadores/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas Wnt , Xenopus laevis/genética , beta Catenina
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