RESUMO
BACKGROUND: In France, on the first of January 2018, 772 underage persons were in jail or about 1.1 % of the incarcerated population. The prevalence of psychiatric disorders among those inmates is high. As a result psychiatric care (and particularly full-time hospitalization) is essential for this population. The unités hospitalières spécialement aménagées (UHSA) are full-time inpatient hospitalization units for inmates in France. Adults but also underage inmates can be admitted to UHSA for voluntary or involuntary hospitalization. However, no study about the characteristics of young patients admitted to UHSA is currently available. The aim of this study is to describe the population of children and adolescent patients hospitalized in these facilities and to evaluate the care provided. METHOD: We conducted a retrospective study, including all the patients under 18 years of age, who have been hospitalized in UHSA since its creation in 2010 until 31 December 2016. Anonymized data concerning socio-demographic profile, clinical symptoms and care provided have been collected from the medical records of each patient. RESULTS: Overall 80 underage patients were included, for 120 hospitalisations in UHSA. Those patients are mainly male (80%) with a mean age of 16.7 years. They are mostly hospitalized with their consent (59%) for stays of about 50 days and frequently after self-harm behaviours. The main diagnoses are anxiety disorders (26%) and psychotic disorders (25%). At the end, 86% of the patients are prescribed a psychotropic drug treatment and 40% of those medical drugs are prescribed outside the guidelines. Finally, several specific problems were identified. Especially, contact with families and educators or access to education programs are very challenging. CONCLUSION: This study highlights the current difficulties encountered in the management of inmate underage patients in full-time psychiatric hospitalization. In this paper, we propose areas for improvement through (1) specific arrangements to receive young patients (specific service's management in order to reinforce the observation of those young people, to facilitate contact with their families, to improve the access to education programs, etc.); (2) specific arrangements in the treatment offered to young patients in UHSA (specific training course for nurses, specific therapeutic programs, etc.); (3) the development of networks working with psychiatric services inside and outside the prison, educators, families and prison services, in order to promote the continuity of cares.
Assuntos
Hospitalização , Transtornos Mentais/psicologia , Prisões/organização & administração , Adolescente , Criança , Internação Compulsória de Doente Mental , Estudos Transversais , Feminino , França/epidemiologia , Humanos , Masculino , Transtornos Mentais/epidemiologia , Prevalência , Prisioneiros/psicologia , Estudos Retrospectivos , Comportamento Autodestrutivo , Adulto JovemRESUMO
PURPOSE: To compare the refractive outcomes of sutureless scleral-fixated Carlevale® intraocular lenses versus Artisan® iris-claw-fixated lenses in terms of surgically induced astigmatism. SETTING: We included patients from the Quinze-Vingts National Ophthalmology Hospital, Paris, from August 2020 to December 2020. DESIGN: This was a single-center retrospective study. METHODS: Each patient included had undergone surgery with a sutureless scleral-fixated Carlevale® foldable intraocular lens or an Artisan® iris-claw lens in the context of secondary implantation. Exclusion criteria included a history of retinal detachment or any other retinal disease. We analyzed postoperative refractive data three months after surgery for the Carlevale group and three months after removal of all sutures for the Artisan group. RESULTS: A total of 25 eyes of 25 patients were included in the Carlevale group and 37 eyes of 36 patients in the Artisan group. At three months, the best-corrected visual acuity was not statistically different, at 0.33(±0.35) and 0.32(±0.33) LogMAR, respectively (P=0.99), and surgically induced astigmatism was significantly lower in the Carlevale group, at 0.538 (±0.560) and 2.30 (±3.97) Diopters, respectively (P<0.001). CONCLUSIONS: In this first comparative study, Carlevale® intraocular lenses appear to offer better refractive accuracy and less induced astigmatism than Artisan® iris-claw lenses, without increasing mean surgical time.
Assuntos
Astigmatismo , Lentes Intraoculares , Astigmatismo/cirurgia , Humanos , Implante de Lente Intraocular/efeitos adversos , Lentes Intraoculares/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/cirurgia , Estudos Retrospectivos , Esclera/cirurgiaRESUMO
This prospective observational cohort study is based on the first 500 patients who requested emergency teleconsultation during the initial days of the COVID-19 lockdown in Paris, France between 20 March and 10 April 2020. It is the first study to assess the utility of emergency teleophthalmology with a simple smartphone application or web browser and a webcam to manage emergency eye care in a population with sudden restricted access to ophthalmologists. In this study, every patient who asked for an ophthalmic emergency consultation in a single specialized center in Paris ('SOS Åil') first had to undergo a teleconsultation appointment to evaluate the indication for a physical consultation to preserve lockdown. Under medical advice only, a physical appointment was given within a day (if necessary). The aim of the study was to describe the population and diagnoses and evaluate the main judgment criteria, defined as the 'ability of teleconsultation to properly indicate a physical consultation for fair diagnosis and treatment in eye emergencies'. This organization has permitted physicians and patients to preserve social distancing while avoiding 3 or 4 physical consultations per person. Notably, 27% of teleconsultations were followed by a physical appointment. There was a mean 4.12-day delay between symptom apparition and consultation, and less than 1 day for traumas, superficial corneal foreign body and neuro-ophthalmological emergencies. There was a 96% sensitivity and 95% specificity to properly evaluate the indication of a physical consultation and only 1.0% misdiagnoses that lead to delayed care. Hence, teleconsultation maintained satisfactory healthcare access to patients with severe ophthalmological disorders while preserving social distancing and sanitary precautions. Therefore, teleconsultation may be seriously considered as a way to efficiently regulate ophthalmic emergencies, especially for patients with limited access to a specialist.
Assuntos
Betacoronavirus , Infecções por Coronavirus/epidemiologia , Oftalmologia/estatística & dados numéricos , Pneumonia Viral/epidemiologia , Quarentena , Telemedicina/estatística & dados numéricos , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Agendamento de Consultas , COVID-19 , Criança , Pré-Escolar , Erros de Diagnóstico , Emergências/epidemiologia , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Oftalmologia/organização & administração , Pandemias , Paris/epidemiologia , Estudos Prospectivos , SARS-CoV-2 , Sensibilidade e Especificidade , Distribuição por Sexo , Telemedicina/métodos , Adulto JovemRESUMO
OBJECTIVE: The aim of this work is the psychometric validation of a self assessment questionnaire about speech in dysarthria. MATERIALS AND METHODS: A prospective study was performed on 91 persons to analyze reliability and validity of this new questionnaire. It is composed of 25 items subdivided in 3 domains: Physical, functional and emotional. We first compared 17 normal speakers to 21 dysarthric patients. Then we analysed the intra-individual variability with 53 patients who completed the questionnaire twice with two weeks interval between the completion. The statistical analysis verified internal consistency of each item, intra-subject reliability was analyzed through Pearson test and clinical validity was calculated through the non parametric Mann Whitney test. RESULTS: The internal consistency reliability was correct (Cronbach's alpha > 0.9). It appeared a statically significant difference between normal speakers and dysarthric patients (p < 0.05). The correlations to the handicap and severity felt were fair ensured us of the content's validity. However the absence of difference for 5 items drove us to eliminate them. Also, analysis the test / retest by the correlation matrix allowed to delete 5 other questions. The obtained total score was 0,861. As for the validity of contents, the correlations in the handicap and in the degree of severity felt by the dysarthric patients were satisfactory. CONCLUSION: The results of this study allows to resume the validation of this questionnaire, its short form of 15 items is particularly adapted to dysarthric patients. It now remains to test its reliability with the medical evolution of the patients. We propose to name it "Phonation Handicap Index".
Assuntos
Distúrbios da Fala/diagnóstico , Inquéritos e Questionários , Adulto , Disartria/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto JovemAssuntos
COVID-19/epidemiologia , Emergências/epidemiologia , Oftalmopatias/epidemiologia , Oftalmopatias/terapia , Quarentena , Consulta Remota/estatística & dados numéricos , Adulto , Idoso , Controle de Doenças Transmissíveis/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oftalmologia/estatística & dados numéricos , Pandemias , Paris/epidemiologia , Satisfação do Paciente/estatística & dados numéricos , Percepção , Quarentena/psicologia , Quarentena/estatística & dados numéricos , SARS-CoV-2 , Telemedicina/estatística & dados numéricosRESUMO
We have recently identified a new G protein-coupled receptor, X-msr, whose expression is associated with the endothelial lineage in Xenopus laevis (Devic, E., Paquereau, L., Vernier, P., Knibiehler, B., Audigier, Y., 1996. Expression of a new G protein-coupled receptor X-msr is associated with an endothelial lineage in Xenopus laevis. Mech. Dev. 59, 129-140). Based on its structural analogy to the human orphan receptor APJ, we cloned the murine msr/apj receptor and analyzed its expression in developing tissues. As observed for X-msr, msr/apj transcripts are detected in the endothelium of the primary blood vessels and the forming heart. In addition, they are expressed in somites, limb bud and branchial arches. This expression pattern is distinct from that of the Flk1 gene and suggests that the msr/apj gene is expressed in a subpopulation of endothelial precursors and a mesenchymal population derived from paraaxial mesoderm.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Receptores de Superfície Celular/genética , Receptores Acoplados a Proteínas G , Proteínas de Xenopus , Sequência de Aminoácidos , Animais , Receptores de Apelina , Vasos Sanguíneos/embriologia , Vasos Sanguíneos/metabolismo , Sistema Cardiovascular/embriologia , Clonagem Molecular , Endotélio Vascular/embriologia , Endotélio Vascular/metabolismo , Humanos , Hibridização In Situ , Botões de Extremidades/metabolismo , Camundongos , Dados de Sequência Molecular , Receptores Proteína Tirosina Quinases/genética , Receptores de Superfície Celular/metabolismo , Receptores de Dopamina D2/genética , Receptores de Fatores de Crescimento/genética , Receptores de Fatores de Crescimento do Endotélio Vascular , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
Over the last few years, many reports have extended our knowledge of the inositol lipid metabolism and brought out some exciting information about the location, the variety and the role of phosphoinositides (PIs). Besides the so-called "canonical PI pathway" leading to the production of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), the precursor of the intracellular second messengers inositol 1,4,5-trisphosphate and diacylglycerol (DAG), many other metabolic pathways have been identified to produce seven different polyphosphoinositides. Several of these quantitatively minor lipid molecules appear to be specifically involved in the control of cellular events, such as the spatial and temporal organisation of key signalling pathways, the rearrangement of the actin cytoskeleton or the intracellular vesicle trafficking. This is consistent with the fact that many of the enzymes, such as kinases and phosphatases, involved in the tight control of the intracellular level of polyphosphoinositides, are regulated and/or relocated through cell surface receptors for extracellular ligands. The remarkable feature of PIs, which can be rapidly synthesised and degraded in discrete membrane domains or even subnuclear structures, places them as ideal regulators and integrators of very dynamic mechanisms of cell regulation. In this review, we will summarise recent studies on the potential location, the metabolic pathways and the role of the different PIs. Some aspects of the temporal synthesis of D3 PIs will also be discussed.
Assuntos
Fosfatidilinositóis/metabolismo , Transdução de Sinais , Animais , Membrana Celular/metabolismo , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Fina , Humanos , Metabolismo dos Lipídeos , Modelos Biológicos , Modelos Químicos , Estrutura Terciária de Proteína , Fatores de TempoRESUMO
Platelets are critical for the maintenance of the integrity of the vascular system and are the first line of defence against haemorrhage. When they encounter a subendothelial matrix exposed by injury to a vessel, platelets adhere, are activated, and become adhesive for other platelets so that they aggregate. alpha IIb/beta 3, a platelet-specific integrin, is largely prominent amongst the adhesion receptors and is essential for platelet aggregation. The ligands for alpha IIb/beta 3 are the multivalent adhesive proteins fibrinogen and von Willebrand factor. In resting platelets, alpha IIb/beta 3 is normally in a low activation state, unable to interact with soluble fibrinogen. Stimulation of platelets with various agonists will induce a conformational change in alpha IIb/beta 3 (inside-out signalling), which is then able to bind soluble fibrinogen resulting in the onset of platelet aggregation. However, fibrinogen binding to its membrane receptor is not simply a passive event allowing the formation of intercellular bridges between platelets. Indeed, a complex signalling pathway triggered by integrin ligation and clustering (outside-in signalling) will regulate the extent of irreversible platelet aggregation and clot retraction. Amongst the signalling enzymes activated downstream of alpha IIb/beta 3 engagement, phosphoinositide 3-kinase plays an important role in the control of the irreversible phase of aggregation.
Assuntos
Plaquetas/metabolismo , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Transdução de Sinais/fisiologia , Animais , Antígenos CD/fisiologia , Antígeno CD47 , Proteínas de Transporte/fisiologia , Humanos , Fosfatidilinositol 3-Quinases/fisiologia , Agregação Plaquetária , Receptor PAR-1 , Receptores de Trombina/fisiologiaRESUMO
Although social skills group interventions for children with autism are common in outpatient clinic settings, little research has been conducted to determine the efficacy of such treatments. This study examined the effectiveness of an outpatient clinic-based social skills group intervention with four high-functioning elementary-aged children with autism. The group was designed to teach specific social skills, including greeting, conversation, and play skills in a brief therapy format (eight sessions total). At the end of each skills-training session, children with autism were observed in play sessions with typical peers. Typical peers received peer education about ways to interact with children with autism. Results indicate that a social skills group implemented in an outpatient clinic setting was effective in improving greeting and play skills, with less clear improvements noted in conversation skills. In addition, children with autism reported increased feelings of social support from classmates at school following participation in the group. However, parent report data of greeting, conversation, and play skills outside of the clinic setting indicated significant improvements in only greeting skills. Thus, although the clinic-based intervention led to improvements in social skills, fewer changes were noted in the generalization to nonclinic settings.
Assuntos
Transtorno Autístico , Comportamento Social , Socialização , Instituições de Assistência Ambulatorial , Transtorno Autístico/diagnóstico , Criança , Feminino , Humanos , Solidão/psicologia , Masculino , Pais , Grupo Associado , Índice de Gravidade de Doença , Apoio Social , Inquéritos e Questionários , Ensino/métodosRESUMO
One method for defining pathways through which children develop severe conduct problems is based on the presence or absence of callous-unemotional (CU) traits. This study investigated potential differences between nonreferred children (mean age = 12.36 years; SD = 1.73) with and without CU traits (n = 98). Children with conduct problems, irrespective of the presence of CU traits, tended to have significant problems in emotional and behavioral regulation. In contrast, CU traits, irespective of the presence of conduct problems, were associated with a lack of behavioral inhibition. Hostile attributional biases were associated with conduct problems but only in boys and in the absence of CU traits. These findings suggest that the processes underlying deficits in emotional and behavioral regulation in children with conduct problems may be different for children with CU traits.
Assuntos
Transtorno da Personalidade Antissocial/diagnóstico , Transtorno da Conduta/diagnóstico , Emoções , Transtorno da Personalidade Antissocial/psicologia , Criança , Transtorno da Conduta/psicologia , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Inibição Psicológica , Masculino , Distribuição Aleatória , Estudos de Amostragem , Índice de Gravidade de Doença , Inquéritos e QuestionáriosRESUMO
OBJECTIVES: This study assessed paternal occupational exposure to di(2-ethylhexyl)phthalate (DEHP) in association with reduced fertility. METHODS: Men working in three plants with DEHP exposure were studied retrospectively. Male and female employees and their partners were invited to participate if they had reported a pregnancy or an attempt to achieve a pregnancy. Postal questionnaires and telephone interviews were used to collect additional data from the men and women, respectively. Information on time to pregnancy was eligible for 326 pregnancies fathered by 193 men. Male exposure to DEHP during every month of their time to pregnancy was classified into one of three exposure categories. The exposure ranged from <0.1 to 2.1 mg/m3. The fathers of only four pregnancies had DEHP exposure of >0.5 mg/m3 during the time to pregnancy. The pregnancies of employed women with unexposed partners or pregnancies of employed men unexposed during the time to pregnancy formed the reference group. RESULTS: The fecundability ratio for time to pregnancy was 1.07 [95% confidence interval (95% CI) 0.84-1.35] for those with low exposure and 0.97 (95% CI 0.70-1.33) for the highly exposed after adjustment for the father's age, mother's age, and length of recall. When the analyses were restricted to first pregnancy, the fecundability ratio was 1.13 (95% Cl 0.83-1.56) for low exposure and 1.02 (95% CI 0.66-1.59) for high exposure. CONCLUSIONS: Time to pregnancy is not prolonged among couples with paternal exposure to DEHP at a mean exposure level of <0.5 mg/m3.
Assuntos
Dietilexilftalato/efeitos adversos , Fertilidade/efeitos dos fármacos , Exposição Ocupacional/efeitos adversos , Exposição Paterna/efeitos adversos , Parceiros Sexuais , Adulto , Indústria Química , Feminino , Humanos , Masculino , Cloreto de Polivinila/efeitos adversos , Gravidez , Inquéritos e Questionários , Suécia , Fatores de TempoRESUMO
The role of callous-unemotional (CU) traits and conduct problems in predicting conduct problem severity, severity and type of aggression, and self-reported delinquency at a 1-year follow-up was investigated in a sample of 98 children (mean age 12.43; SD = 1.72) recruited from a community-wide screening. Children with both CU traits and conduct problems had a greater number and variety of conduct problems at follow-up than children who at the screening had high levels of conduct problems alone. However, this poorer outcome for children with CU traits could largely be accounted for by differences in initial level of conduct problem severity. Children with CU traits and conduct problems were also at risk for showing higher levels of aggression, especially proactive aggression, and self-reported delinquency. Importantly, these outcomes could not be solely explained by initial level of conduct problem severity. Finally, CU traits predicted self-reported delinquency in some children who did not initially show high levels of conduct problems and this predictive relationship seemed to be strongest for girls in the sample who were high on CU traits but who did not show significant conduct problems.
Assuntos
Afeto , Agressão/psicologia , Transtorno da Personalidade Antissocial/diagnóstico , Transtorno da Personalidade Antissocial/epidemiologia , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Transtorno da Conduta/diagnóstico , Transtorno da Conduta/epidemiologia , Crime/estatística & dados numéricos , Autoavaliação (Psicologia) , Criança , Feminino , Seguimentos , Humanos , Masculino , Valor Preditivo dos Testes , Inquéritos e QuestionáriosRESUMO
This study examined the structure of psychopathic traits in 2 samples of children. The nonreferred community sample included 1,136 children recruited from elementary schools in 2 school districts in the southeastern United States. The clinic sample included 160 children referred to an outpatient mental health clinic serving the same geographic region. In both samples, parent and teacher ratings of psychopathic traits were subjected to a principal-axis factor analysis, and the congruence of the factor structure across samples was examined using confirmatory factor analysis. In both samples, 1 dimension that consisted of the callous and unemotional traits that have been hallmarks of most clinical descriptions of psychopathy was isolated. Two other dimensions consisting of narcissistic traits and impulsivity emerged in the community sample. Both the narcissism and impulsivity dimensions were highly related to symptoms of oppositional defiant disorder, conduct disorder, and attention deficit hyperactivity disorder. However, the callous and unemotional traits were only weakly associated with these symptoms after controlling for the other dimensions of psychopathy.
Assuntos
Transtorno da Personalidade Antissocial/diagnóstico , Transtornos do Comportamento Infantil/diagnóstico , Programas de Rastreamento , Determinação da Personalidade/estatística & dados numéricos , Transtorno da Personalidade Antissocial/psicologia , Criança , Transtornos do Comportamento Infantil/psicologia , Feminino , Humanos , Masculino , Psicometria , Encaminhamento e Consulta , Reprodutibilidade dos Testes , Fatores de RiscoRESUMO
The aim of this prospective investigation was to validate a French version of the Voice Handicap Index (VHI). A population of 52 normal subjects and 63 patients with voice disorders replied to the questionnaire at the day of their first consultation and ten to thirty days after the consultation (before any treatment). Reproducing the methodology of the American authors, the test-retest reliability and the internal consistency reliability were measured. The validity and the sensibility related to a non dysphonic population were also analysed. Regarding the normal subjects, the maximum scores for total score and subscale scores were 20 (total), 12 (physical), 7 (functional), 6 (Emotional). These scores are statistically different when compared with pathological subjects (p < 0.00001). Test-Retest stability of the pathological subjects was found to be satisfactory for both total score and subscale scores (r > 0.87). From this data set, the critical difference scores were derived for the VHI total score (15 points), for the physical subscale (9 points) and for the functional and emotional.subscales (6 points each). As for as the internal consistency reliability, Cronbach's alpha is correct (r > 7) for the pathological subjects. Yet, the analysis of the validity reply by reply, reveals some abnormalities. In conclusion, the validity of the French translation of the VHI is confirmed but the results prompt us to improve the quality of the translation.
Assuntos
Perfil de Impacto da Doença , Inquéritos e Questionários , Distúrbios da Voz/diagnóstico , Adulto , Idoso , Humanos , Idioma , Pessoa de Meia-Idade , Estudos ProspectivosAssuntos
Sistemas de Informação em Laboratório Clínico/economia , Eficiência Organizacional , Laboratórios Hospitalares/economia , Alabama , Autoanálise , Análise Custo-Benefício , Hospitais com mais de 500 Leitos , Imunoensaio/instrumentação , Imunoensaio/métodos , Renda , Serviço Hospitalar de Compras , Carga de TrabalhoRESUMO
Preparing a large hospital for a Joint Commission on Accreditation of Healthcare Organizations (JCAHO) survey is always a challenging endeavor. Because staff members have diverse learning needs it is important that staff be educated in the JCAHO standards. In this article, the author describes the educational strategies used to prepare a healthcare organization for an impending JCAHO survey. Learning styles, the domains of learning, and the accessibility to education by the satellite facilities were determining factors in the selection of the various educational strategies.
Assuntos
Educação Continuada em Enfermagem/organização & administração , Capacitação em Serviço/organização & administração , Joint Commission on Accreditation of Healthcare Organizations , Recursos Humanos de Enfermagem Hospitalar/educação , Centros Médicos Acadêmicos , Humanos , Avaliação das Necessidades , Desenvolvimento de Programas , Avaliação de Programas e Projetos de Saúde , Materiais de EnsinoRESUMO
A large urban university medical center used a unique set of strategies in preparation for its triennial survey conducted by the Joint Commission on Accreditation of Healthcare Organizations. Although the medical center had experienced many Joint Commission surveys, this particular survey was the first to include associated physician offices in multiple diverse settings. To address these challenges, the hospital developed a structure and process that engaged all levels of staff and ensured a successful survey outcome.
Assuntos
Centros Médicos Acadêmicos/normas , Acreditação/normas , Joint Commission on Accreditation of Healthcare Organizations , Técnicas de Planejamento , Centros Médicos Acadêmicos/organização & administração , Acreditação/organização & administração , Assistência Ambulatorial , Fidelidade a Diretrizes , Pesquisas sobre Atenção à Saúde , Hospitais com mais de 500 Leitos , Capacitação em Serviço , Avaliação de Resultados em Cuidados de Saúde , Gestão da Qualidade Total , VirginiaRESUMO
Myotubular myopathy (MTM1) is an X-linked disease, characterized by severe neonatal hypotonia and generalized muscle weakness, with pathological features suggesting an impairment in maturation of muscle fibres. The MTM1 gene encodes a protein (myotubularin) with a phosphotyrosine phosphatase consensus. It defines a family of at least nine genes in man, including the antiphosphatase hMTMR5/Sbf1 and hMTMR2, recently found mutated in a recessive form of Charcot-Marie-Tooth disease. Myotubularin shows a dual specificity protein phosphatase activity in vitro. We have performed an in vivo test of tyrosine phosphatase activity in Schizosaccharomyces pombe, indicating that myotubularin does not have a broad specificity tyrosine phosphatase activity. Expression of active human myotubularin inhibited growth of S.pombe and induced a vacuolar phenotype similar to that of mutants of the vacuolar protein sorting (VPS) pathway and notably of mutants of VPS34, a phosphatidylinositol 3-kinase (PI3K). In S.pombe cells deleted for the endogenous MTM homologous gene, expression of human myotubularin decreased the level of phosphatidylinositol 3-phosphate (PI3P). We have created a substrate trap mutant which shows relocalization to plasma membrane projections (spikes) in HeLa cells and was inactive in the S.pombe assay. This mutant, but not the wild-type or a phosphatase site mutant, was able to immunoprecipitate a VPS34 kinase activity. Wild-type myotubularin was also able to directly dephosphorylate PI3P and PI4P in vitro. Myotubularin may thus decrease PI3P levels by down-regulating PI3K activity and by directly degrading PI3P.
Assuntos
Miopatias Congênitas Estruturais/genética , Fosfatidilinositol 3-Quinases/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Proteínas Tirosina Fosfatases/genética , Animais , Linhagem Celular , Regulação para Baixo , Humanos , Testes de Precipitina , Proteínas Tirosina Fosfatases/metabolismo , Proteínas Tirosina Fosfatases não Receptoras , Schizosaccharomyces/enzimologia , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , TransfecçãoRESUMO
SH2-containing inositol-5-phosphatase 1 (SHIP1) was originally identified as a 145 kDa protein that became tyrosine-phosphorylated in response to multiple cytokines. It is now well established that SHIP1 is specifically expressed in haemopoietic cells and is important as a negative regulator of signalling. We found recently that SHIP1 was present in human blood platelets as an Ins(1,3,4, 5)P(4)-phosphatase and a PtdIns(3,4,5)P(3)-5-phosphatase that became tyrosine-phosphorylated and was relocated to the cytoskeleton in an integrin-dependent manner. Here we report biochemical and pharmacological evidence that the tyrosine kinase pp60(c-src) is constitutively associated with SHIP1 and is involved in its tyrosine phosphorylation downstream of integrin engagement in thrombin-activated human platelets. The use of cytochalasin D allowed us to demonstrate that the actin cytoskeleton reorganization induced on thrombin stimulation was not required for its integrin-mediated phosphorylation. Moreover, the integrin-dependent relocation of SHIP1 to the cytoskeleton did not require its tyrosine phosphorylation. These results suggest that SHIP1 is first recruited to the integrin-linked signalling complexes and then becomes tyrosine-phosphorylated through a Src-kinase-dependent mechanism but independently of the actin cytoskeleton reorganization.