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1.
Pediatr Obes ; 14(4): e12481, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30417593

RESUMO

BACKGROUND: Given evidence suggesting that sleep impacts on metabolic processes, interventions targeting sleep may improve child physical activity (PA). OBJECTIVES: To describe the potential effect of an intervention to increase sleep on young children's (3-6 years) moderate to vigorous PA (MVPA) and total PA. To determine adherence to the intervention, impact on sleep duration as well as feasibility, uptake and acceptability was also assessed. METHODS: Pilot randomized controlled trial with 76 parent-child dyads randomly allocated to an intervention (n = 38) or control group (n = 38). Parents in the intervention group received a 3-month theory-informed intervention consisting of an online video, a telephone call and two text messages. Child PA was assessed using accelerometers at baseline and approximately 3 months. Parents also completed a sleep log and a telephone interview. RESULTS: The consent rate was 41% (76/186). Estimated effect size for the intervention relative to control was 10.8 min/day for MVPA, 2.7 min/day for PA and 0.9 h for sleep. Sixteen (44%) parents accessed the video, and 18 (50%) received the telephone call. Over 40% of parents found the video and telephone call useful/very useful. CONCLUSIONS: This study reports promising effects that an intervention targeting sleep may improve child MVPA and sleep duration. Some modifications to data collection methods and intervention delivery are needed.


Assuntos
Exercício Físico/fisiologia , Promoção da Saúde/métodos , Sono/fisiologia , Acelerometria , Austrália , Criança , Pré-Escolar , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pais , Projetos Piloto , Estudos Prospectivos
2.
Clin Rheumatol ; 31(5): 877-80, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22215120

RESUMO

Anti-CCP (cyclic citrullinated peptide) is considered the most useful laboratory tool in the diagnosis of rheumatoid arthritis (RA). Some authors have also found this autoantibody in patients with scleroderma (SSc). The study aimed to investigate the prevalence of anti-CCP antibodies in SSc patients from Southern Brazil and their association with clinical and serological profile of the disease. We studied 76 patients with SSc and 100 healthy volunteers for presence of anti-CCP. SSc patients charts were reviewed for clinical and laboratory data. In the SSc group, the diffuse form was present in 20.5%; 62.8% had the limited form; 14.1% had overlap with systemic lupus or polymyositis and 2.5% had SSc sine scleroderma. Anti-CCP was found in nine of 78 (11.5%) SSc patients and in one of 100 healthy volunteers (p = 0.0054). No relationship was found with arthritis, skin Rodnan m score, esophageal dysmotility, myocarditis, pulmonary hypertension and lung fibrosis. Positive association was observed with arthralgias (p = 0.02). Also, no relationship was noted with the presence of anti-centromere antibodies, anti-Scl-70, anti-RNP or rheumatoid factor. Anti-CCP are more common in SSc patients than in controls. Arthralgias but not arthritis or rheumatoid factor are more frequent in anti-CCP positive patients.


Assuntos
Anticorpos/sangue , Peptídeos Cíclicos/imunologia , Esclerodermia Difusa/imunologia , Esclerodermia Limitada/imunologia , Biomarcadores/sangue , Comorbidade , Feminino , Humanos , Lúpus Eritematoso Sistêmico/epidemiologia , Masculino , Pessoa de Meia-Idade , Polimiosite/epidemiologia , Esclerodermia Difusa/epidemiologia , Esclerodermia Difusa/patologia , Esclerodermia Limitada/epidemiologia , Esclerodermia Limitada/patologia , Estudos Soroepidemiológicos
3.
Ann Oncol ; 23(1): 193-200, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21427065

RESUMO

BACKGROUND: Osteonecrosis of the jaw (ONJ) is associated with bisphosphonate (BP) therapy and invasive dental care. An Interdisciplinary Care Group (ICG) was created to evaluate dental risk factors and the efficacy of a preventive restorative dental care in the reduction of ONJ risk. PATIENTS AND METHODS: This prospective single-center study included patients with bone metastases from solid tumors. Patients who received at least one BP infusion between October 2005 and 31 August 2009 underwent one or more ICG evaluation and regular dental examinations. We also retrospectively evaluated patients with bone metastases from solid tumors who did not undergo dental preventive measures. RESULTS: Of 269 patients, 211 had received at least one infusion of BP therapy: 62% were BP naive and 38% had previous BP exposure. Of these 211 patients followed for 47 months, 6 patients developed ONJ (2.8%). Of 200 patients included in the retrospective analysis, 11 patients developed ONJ (5.5%). CONCLUSIONS: In comparison with published ONJ rates and those extrapolated from the retrospective analysis, the observed ONJ rate in the prospective group was lower, suggesting that implementation of a preventive dental program may reduce the risk of ONJ in metastatic patients treated with i.v. BP therapy.


Assuntos
Osteonecrose da Arcada Osseodentária Associada a Difosfonatos/prevenção & controle , Conservadores da Densidade Óssea/efeitos adversos , Assistência Odontológica/métodos , Difosfonatos/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/secundário , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco
4.
Transplant Proc ; 42(2): 521-2, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20304183

RESUMO

OBJECTIVE: The objective of this study was to identify the incidence of posttransplantation lymphoproliferative disease (PTLD) among children within 1 year after liver transplantation. METHODS: This retrospective review analyzed information in medical charts of pediatric (younger than 18 years of age) recipients of liver transplants between September 2000 and December 2007. RESULTS: Seventy-one patients underwent a liver transplantation and 7 (9.85%) developed PTLD. Among this group, 6 children were girls and 1 was a boy. The median age at transplantation was 35.14 months. Indications that led the children to have their transplantation were 1 case of hemangioendothelioma, 1 case of autoimmune hepatic cirrhosis, 1 case of alpha-1-antitrypsin deficiency, and 4 cases of biliary atresia. The most frequent symptoms were splenomegaly, diarrhea, and fever. The median time from the first symptoms to the initial treatment was 9.7 days. The standard treatment was withdrawal of immunosuppression and close observation of tacrolimus levels and liver function tests associated with antiviral drugs and chemotherapy. Four among 7 children died; 3 children recovered. All 3 children who recovered has presented at the transplantation center within 5 days of initiation of symptoms (P = .033896). CONCLUSION: Despite its rarity, when it occurs, PTLD shows a high mortality rate. Therefore, it is necessary to have interdisciplinary work between the medical team that performs the transplantation and those promoting the primary care to diagnose the disease early and treat it effectively.


Assuntos
Transplante de Fígado/efeitos adversos , Transtornos Linfoproliferativos/epidemiologia , Complicações Pós-Operatórias/epidemiologia , Atresia Biliar/cirurgia , Criança , Pré-Escolar , Infecções por Vírus Epstein-Barr/cirurgia , Feminino , Humanos , Imunossupressores/uso terapêutico , Lactente , Hepatopatias/classificação , Hepatopatias/cirurgia , Transplante de Fígado/mortalidade , Masculino , Prevalência , Estudos Retrospectivos , Esplenomegalia/etiologia , Tacrolimo/uso terapêutico , Deficiência de alfa 1-Antitripsina/cirurgia
5.
Neuroscience ; 163(4): 1327-39, 2009 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-19619619

RESUMO

Frogs were treated with a single dose of gentamicin administered intraotically to produce severe degeneration of posterior semicircular canal hair cells and to evaluate the time course of functional damage and recovery both at pre- and postsynaptic level. In isolated canal preparations the endoampullar potential, which reflects the summed receptor potentials of crista hair cells, was progressively reduced in amplitude and completely abolished 6 days after gentamicin treatment. At this time the crista epithelium was devoid of hair cells. The recovery of the endoampullar potential began around 9 days after the ototoxic insult and its amplitude progressively increased to reach, after 20 days, values close to those observed in control experiments. The endoampullar potential amplitude was related to the degree of hair cell regeneration in the crista epithelium. Consistent with the presynaptic damage, the slow generator potential (representing the summed miniature excitatory postsynaptic potential [mEPSP] activity of all posterior nerve fibres) and the resting and evoked spike discharge recorded from the whole ampullar nerve were abolished 6 days after gentamicin treatment. The recovery of the background and evoked afferent activity showed different behaviours. Background spike activity became detectable around 8 days after the ototoxic insult, but was not modulated by canal stimulation at this time, and no generator potential was detected. Moreover, the resting spike frequency fully recovered and reached control values around 15 days after gentamicin treatment, whereas the evoked activity attained normal values only 20 days after the ototoxic insult. These results were confirmed by intracellular recordings from single afferent fibres of the ampullar nerve in intact labyrinth preparations. Absence of any resting and evoked discharge was the most common pattern observed in the early period from 7 to 8 days after gentamicin treatment. Fifty-five percent of impaled afferents were silent while the others showed low resting frequencies of mEPSPs and spikes, and were unresponsive to canal rotation. In the intermediate period from 14 to 15 days after gentamicin treatment, background mEPSP and spike frequencies approached those evaluated in control experiments, but the frequencies of the evoked mEPSPs and spikes were clearly lower than in controls. In the late period, from 18 to 20 days after the ototoxic insult, the impaled afferents showed normal evoked mEPSP and spike frequencies. The present data indicate that the frog semicircular canal completely recovers its pre- and postsynaptic activity following severe ototoxic insult. During the regeneration process, the cytoneural junction regains function and the resting discharge reappears before recovery of mechanoelectrical transduction.


Assuntos
Gentamicinas/toxicidade , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Inibidores da Síntese de Proteínas/toxicidade , Canais Semicirculares/efeitos dos fármacos , Canais Semicirculares/fisiopatologia , Potenciais de Ação , Animais , Epitélio/efeitos dos fármacos , Epitélio/fisiologia , Potenciais Evocados Auditivos , Potenciais Pós-Sinápticos Excitadores , Células Ciliadas da Ampola/efeitos dos fármacos , Células Ciliadas da Ampola/fisiologia , Potenciais da Membrana , Regeneração Nervosa/fisiologia , Neurônios Aferentes/efeitos dos fármacos , Neurônios Aferentes/fisiologia , Terminações Pré-Sinápticas/efeitos dos fármacos , Terminações Pré-Sinápticas/fisiologia , Rana esculenta , Recuperação de Função Fisiológica , Sinapses/efeitos dos fármacos , Sinapses/fisiologia , Fatores de Tempo
6.
Oncology ; 69(5): 408-13, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16319512

RESUMO

BACKGROUND: Treating patients with anthracycline- and taxane-pretreated metastatic breast cancer is challenging. This study evaluated the activity and safety of a combination of cisplatin and capecitabine in this setting. PATIENTS AND METHODS: Thirty-nine consecutive patients entered the study. All had experienced failures or relapse after previous treatment with anthracyclines and taxanes plus/minus other chemotherapeutic regimens. The present treatment consisted of intravenous cisplatin 20 mg/m(2) every week for 6 weeks, followed by 1 week of rest, and oral capecitabine 1,000 mg/m(2) twice daily for 14 days, followed by a 7-day rest period. RESULTS: Objective response was obtained in 14 patients (35.9%), with complete remission in 3 (7.7%). Median time to progression was 5.2 months and survival was 10.9 months in the entire population and 8.7 and 16.5 months in the responding patients, respectively. The dose-limiting toxicity for the regimen was leucopenia, while gastrointestinal discomfort was the most frequent cause of capecitabine reduction or delay. CONCLUSIONS: The cisplatin and capecitabine combination regimen is active and manageable. It seems to be non-cross resistant to anthracyclines and taxanes.


Assuntos
Antraciclinas/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Neoplasias da Mama/tratamento farmacológico , Cisplatino/administração & dosagem , Desoxicitidina/análogos & derivados , Imunoterapia/métodos , Taxoides/uso terapêutico , Células Apresentadoras de Antígenos/citologia , Capecitabina , Células Dendríticas/citologia , Desoxicitidina/administração & dosagem , Progressão da Doença , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Fluoruracila/análogos & derivados , Genes Reporter , Proteínas de Fluorescência Verde/metabolismo , Antígenos HLA-A/imunologia , Antígeno HLA-A24 , Humanos , Interferon gama/metabolismo , Leucócitos Mononucleares/metabolismo , Microscopia de Fluorescência , Metástase Neoplásica , RNA Mensageiro/metabolismo , Indução de Remissão , Fatores de Tempo , Transcrição Gênica , Resultado do Tratamento
7.
J Intellect Disabil Res ; 49(Pt 4): 260-8, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15816813

RESUMO

BACKGROUND: Sleep problems are common in typically developing (TD) children and in children with autism, however, less is known about the sleep of children with Asperger's disorder (AD). The aim of this study was to compare sleep patterns of children with autism and AD to a TD group of children. METHODS: Sixty-six parents of TD children, 53 parents of children with autism, and 52 parents of children with AD completed a survey on their child's sleep patterns, the nature and severity of any sleep problems and success of any treatment attempted. RESULTS: The results showed high prevalence of sleep problems with significantly more problems reported in the autism and AD groups (TD = 50%, autism = 73%, AD = 73%), with no significant differences between groups on severity or type of sleep problem. Children with AD were significantly more likely to be sluggish and disoriented after waking and had a higher Behavioral Evaluation of Disorders of Sleep (BEDS) total score compared to the other two groups. The autism and AD groups reported significantly better treatment success for medication compared to the TD group. The autism group reported significantly better success for behavioural treatment compared to the AD group. CONCLUSIONS: In conclusion, children with AD may have more symptoms of sleep disturbance, and different types of sleep problems than children with autism. As this is the first study to compare autism and AD and to survey treatment outcomes, further research is needed to validate these findings.


Assuntos
Síndrome de Asperger/epidemiologia , Transtorno Autístico/epidemiologia , Desenvolvimento Infantil , Transtornos do Sono-Vigília/epidemiologia , Inquéritos e Questionários , Síndrome de Asperger/diagnóstico , Transtorno Autístico/diagnóstico , Criança , Pré-Escolar , Tratamento Farmacológico/estatística & dados numéricos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Feminino , Humanos , Masculino , Prevalência , Índice de Gravidade de Doença , Transtornos do Sono-Vigília/diagnóstico , Transtornos do Sono-Vigília/tratamento farmacológico
8.
Gene ; 230(1): 81-90, 1999 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-10196477

RESUMO

In the context of a project aimed at the identification of zinc finger proteins involved in skeletal muscle histogenesis and differentiation, we isolated a murine gene, named ZT2. The 2.44kb partial cDNA clone corresponds to the 3' region of the gene, and contains a 0.54kb open reading frame encoding four C2H2-like zinc finger domains, organized in tandem. This cDNA hybridizes with multiple transcripts (2, 4.5 and 7kb), whose expression levels vary in different tissues and at different developmental stages in the same tissue. At least in skeletal muscle we observed differences in the polyadenylation state of the transcripts at different stages of development. Moreover, ZT2 expression is correlated with cell proliferation and transformation. Sequence analysis and genetic mapping indicate that ZT2 is the homologue of ZNF125, one of the linked zinc finger encoding genes localized on human Chr 11q23. In humans, a high frequency of tumor-associated translocations is found in this chromosome region. As expected, ZT2 maps to the corresponding region on chromosome 9 in the mouse.


Assuntos
Proteínas de Ligação a DNA/genética , Proteínas Musculares/genética , Dedos de Zinco/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Diferenciação Celular , Células Cultivadas , Mapeamento Cromossômico , Clonagem Molecular , Sequência Consenso , Proteínas de Ligação a DNA/química , Ligação Genética , Humanos , Fatores de Transcrição Kruppel-Like , Camundongos , Dados de Sequência Molecular , Proteínas Musculares/química , Músculo Esquelético/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alinhamento de Sequência
9.
J Int Neuropsychol Soc ; 2(5): 419-25, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9375167

RESUMO

Recent investigations have distinguished between ophthalmokinetic and melokinetic factors of unilateral neglect. The aim of our study was to investigate the possible dissociation between melokinetic (premotor) and perceptual factors, avoiding any overt oculokinetic components. We asked four blindfolded left neglect patients to set a dichotic sound in central position, by moving a handle controlling the difference of intensity between the sounds delivered to the left and to the right ears. Two conflicting conditions were used. In the congruent condition, the sound moved in the same direction as the hand movement; in the noncongruent condition, it moved in the opposite direction. One patient performed as if suffering from melokinetic neglect, and another as if suffering from perceptual neglect. The behavior of the other two subjects did not lend itself to a clearcut interpretation.


Assuntos
Atenção , Dano Encefálico Crônico/psicologia , Infarto Cerebral/psicologia , Dominância Cerebral , Desempenho Psicomotor , Localização de Som , Idoso , Dano Encefálico Crônico/diagnóstico , Infarto Cerebral/diagnóstico , Testes com Listas de Dissílabos , Feminino , Lateralidade Funcional , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos
10.
Mech Dev ; 54(1): 107-17, 1996 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8808410

RESUMO

ZT3, isolated from a murine muscle cell cDNA library by a low-stringency hybridization, encodes a zinc finger domain containing factor with a transcript of 5.0 kb. A 3' 2.5 kb partial nucleotide sequence contains an ORF of 1.5 kb where 17 canonical C2H2 zinc finger domains organized in tandem were identified. It maps on mouse chromosome 11, close to two mutations which affect skeletal formation. ZT3 expression depends upon differentiation of myogenic cells in culture, since it is upregulated with myogenin and inhibited in scr-transfected C2C12 cells. ZT3 is not expressed in NIH3T3 or C3H10T1/2 fibroblasts, but is induced when fibroblasts are myogenically converted by transfection with the muscle regulatory genes (MRFs). Its expression is also upregulated in the rhabdomyosarcoma cell line RD induced to myogenic differentiation by TPA treatment. In postimplantation embryos, ZT3 is diffusely expressed but higher expression is detectable in the neural tube and encephalic vesicles, in the somites and, at a high level, in the limb buds as they form. During further development ZT3 is expressed in many tissues of neuroectodermal and mesodermal origin, but its expression decreases during fetal development and in the adult it is restricted to skeletal and cardiac muscle and to spleen. This pattern of expression suggests a possible role played by ZT3 in differentiating skeletal muscle. Its expression in other tissues is compatible with the suggestion that members of this class of DNA-binding factors play different roles during post-implantation development and in the adult life.


Assuntos
Proteínas de Ligação a DNA/biossíntese , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Musculares/biossíntese , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Células 3T3 , Sequência de Aminoácidos , Animais , Sequência de Bases , Diferenciação Celular , Linhagem Celular , Mapeamento Cromossômico , Cruzamentos Genéticos , DNA Complementar/genética , Proteínas de Ligação a DNA/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Biblioteca Gênica , Coração/embriologia , Coração/crescimento & desenvolvimento , Fatores de Transcrição Kruppel-Like , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Desenvolvimento Muscular , Proteínas Musculares/genética , Músculo Esquelético/embriologia , Músculo Esquelético/crescimento & desenvolvimento , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Baço/embriologia , Baço/crescimento & desenvolvimento , Baço/metabolismo
11.
Cell Growth Differ ; 6(7): 845-52, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7547506

RESUMO

Human rhabdomyosarcoma RD cells express the myogenic regulatory factors MyoD and myogenin but differentiate spontaneously very poorly. Prolonged treatment of RD cells with the protein kinase C (PKC) activator 12-O-tetradecanoylphorbol-13-acetate (TPA) induces growth arrest and myogenic differentiation as shown by the accumulation of alpha-actin and myosin light and heavy chains, without affecting the expression of MyoD and myogenin. In this study, we show that short-term phorbol ester treatment of the cultures is sufficient to trigger myogenic differentiation but not growth arrest. Furthermore, PKC inhibitors, such as staurosporine or calphostin C, prevent TPA-induced differentiation but not cell growth arrest. These data suggest that the two events are mediated by different pathways; a possible interpretation is that the activation of one or more PKC isoforms mediates the induction of differentiation, whereas the down-regulation of the same or different isoforms mediates the growth arrest. To address the mechanism whereby TPA affects cell growth and differentiation in RD cells, we first analyzed PKC isoenzyme distribution. We found that RD cells express the alpha, beta 1, gamma, and sigma PKC isoenzymes. Only the alpha isoform is exclusively found in the soluble fraction, but it translocates to the membrane fraction within 5 min of TPA treatment and is completely down-regulated after 6 h. The other isoenzymes are found associated to both the soluble and the particulate fractions and are down-regulated after long-term TPA treatment. By immunofluorescence analysis, we show that the PKC alpha down-regulation is specific for those cells that respond to TPA by activating the muscle phenotype. We propose that TPA-induced differentiation in RD cells is mediated by the transient activation of PKC alpha, which activates some of the intracellular events that are necessary for MyoD and myogenin transacting activity and for the induction of terminal differentiation of RD cells. By contrast, the constitutively active beta 1 and sigma are responsible for the maintenance of cell growth, and their down-regulation is responsible for long-term TPA-induced cell growth arrest.


Assuntos
Inibidores do Crescimento/fisiologia , Isoenzimas/fisiologia , Proteína Quinase C/fisiologia , Rabdomiossarcoma/enzimologia , Rabdomiossarcoma/patologia , Acetato de Tetradecanoilforbol/farmacologia , Sequência de Aminoácidos , Western Blotting , Diferenciação Celular/efeitos dos fármacos , Indução Embrionária/efeitos dos fármacos , Ativação Enzimática , Feto/citologia , Humanos , Imuno-Histoquímica , Dados de Sequência Molecular , Proteína Quinase C-alfa , Fatores de Tempo , Células Tumorais Cultivadas/efeitos dos fármacos
12.
Acta Neurol Scand ; 90(1): 34-8, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7941954

RESUMO

Recent studies have suggested that patients with Parkinson's disease (PD) share many of the behavioral deficits found following lesions to the pre-frontal cortex. We assessed the performance of a group of 22 mildly impaired, not-demented parkisonians (I or II Hoehn & Yahr stage) in a test of classification and recall of pictures of familiar objects, which has been demonstrated to be sensitive to frontal damage in patients with unilateral cerebral excision. Parkinsonians utilized fewer categories than normal controls for object classification, while no significant difference was found in the immediate and delayed recall scores. These results support the contention that a subclinical dysfunction of frontal type may be present even in the early stages of PD. A subanalysis of the data suggests that this dysfunction could possibly be aggravated by anticholinergic drugs.


Assuntos
Transtornos Cognitivos/fisiopatologia , Doença de Parkinson/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Adulto , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos
13.
Exp Cell Res ; 208(1): 209-17, 1993 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8395398

RESUMO

RD cells (a cell line derived from a human rhabdomyosarcoma) undergo a very limited myogenic differentiation despite the fact that they express several myogenic determination genes. Since we have previously shown (Aguanno et al., Cancer Res. 50, 3377, 1990) that the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) induces myogenic differentiation in these cells, in this paper we investigate the mechanism by which TPA interferes with the expression and/or function of the myogenic determination genes. Northern blot analysis revealed that RD cells express the myf3 (the human analog of MyoD) and myf4 (the human analog of myogenin) transcripts, but not myf5 or myf6 transcripts. The myf3 and the myf4 gene products are correctly translated and accumulated in the nuclei as shown by immunofluorescence analysis. The tumor promoter (TPA) does not modify the pattern of expression of the myf factors while it induces the accumulation of muscle-specific transcripts, such as alpha-actin and fast myosin light chain 1, and their corresponding proteins. On the other hand, within 1 day of treatment, TPA inhibits the expression of the Id gene, which is a negative regulator of MyoD activity. However, while the TPA-induced inhibition of Id message accumulation correlates with differentiation, cell confluence also causes a reduction in Id message accumulation, without inducing differentiation. Under our experimental conditions, overexpression of any of the myf cDNAs in RD cells does induce spontaneous differentiation but enhances the effect of TPA treatment independently from the level of the expressed message. These data suggest that differentiation of RD cells is likely to depend upon the activity of complexes containing the various members of the MyoD family, which can be regulated by proteins affecting MyoD dimerization such as Id, but also by other mechanisms induced by TPA, such as phosphorylation.


Assuntos
Músculos/citologia , Rabdomiossarcoma/patologia , Diferenciação Celular/efeitos dos fármacos , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Imunofluorescência , Expressão Gênica , Humanos , Técnicas In Vitro , Proteínas Musculares/fisiologia , Proteína MyoD , Miogenina , Miosinas/genética , RNA Mensageiro/genética , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas
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