Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
1.
Int J Behav Nutr Phys Act ; 15(1): 36, 2018 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-29618384

RESUMO

BACKGROUND: The interpretation of previous studies on the association of physical activity and sedentary behaviour with psychological health is limited by the use of mostly self-reported physical activity and sedentary behaviour, and a focus on Western populations. We aimed to explore the association of self-reported and devise-based measures of physical activity and sedentary behaviour domains on psychological distress in an urban multi-ethnic Asian population. METHODS: From a population-based cross-sectional study of adults aged 18-79 years, data were used from an overall sample (n = 2653) with complete self-reported total physical activity/sedentary behaviour and domain-specific physical activity data, and a subsample (n = 703) with self-reported domain-specific sedentary behaviour and accelerometry data. Physical activity and sedentary behaviour data were collected using the Global Physical Activity Questionnaire (GPAQ), a domain-specific sedentary behaviour questionnaire and accelerometers. The Kessler Screening Scale (K6) and General Health Questionnaire (GHQ-12) were used to assess psychological distress. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals, adjusted for socio-demographic and lifestyle characteristics. RESULTS: The sample comprised 45.0% men (median age = 45.0 years). The prevalence of psychological distress based on the K6 and GHQ-12 was 8.4% and 21.7%, respectively. In the adjusted model, higher levels of self-reported moderate-to-vigorous physical activity (MVPA) were associated with significantly higher odds for K6 (OR = 1.47 [1.03-2.10]; p-trend = 0.03) but not GHQ-12 (OR = 0.97 [0.77-1.23]; p-trend = 0.79), when comparing the highest with the lowest tertile. Accelerometry-assessed MVPA was not significantly associated with K6 (p-trend = 0.50) nor GHQ-12 (p-trend = 0.74). The highest tertile of leisure-time physical activity, but not work- or transport-domain activity, was associated with less psychological distress using K6 (OR = 0.65 [0.43-0.97]; p-trend = 0.02) and GHQ-12 (OR = 0.72 [0.55-0.93]; p-trend = 0.01). Self-reported sedentary behaviour was not associated with K6 (p-trend = 0.90) and GHQ-12 (p-trend = 0.33). The highest tertile of accelerometry-assessed sedentary behaviour was associated with significantly higher odds for K6 (OR = 1.93 [1.00-3.75]; p-trend = 0.04), but not GHQ-12 (OR = 1.34 [0.86-2.08]; p-trend = 0.18). CONCLUSIONS: Higher levels of leisure-time physical activity and lower levels of accelerometer-based sedentary behaviour were associated with lower psychological distress. This study underscores the importance of assessing accelerometer-based and domain-specific activity in relation to mental health, instead of solely focusing on total volume of activity.


Assuntos
Acelerometria , Povo Asiático , Exercício Físico , Comportamento Sedentário , Estresse Psicológico/epidemiologia , População Urbana , Adolescente , Adulto , Idoso , Estudos Transversais , Etnicidade , Feminino , Humanos , Estilo de Vida , Modelos Logísticos , Masculino , Saúde Mental , Pessoa de Meia-Idade , Autorrelato , Singapura/epidemiologia , Estresse Psicológico/fisiopatologia , Inquéritos e Questionários , Adulto Jovem
2.
Obes Rev ; 17(5): 467-81, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26990220

RESUMO

Prolonged sedentary behaviour has been associated with various detrimental health risks. Workplace sitting is particularly important, providing it occupies majority of total daily sedentary behaviour among desk-based employees. The aim of this systematic review and meta-analysis was to examine the effectiveness of workplace interventions overall, and according to different intervention strategies (educational/behavioural, environmental and multi-component interventions) for reducing sitting among white-collar working adults. Articles published through December 2015 were identified in five online databases and manual searches. Twenty-six controlled intervention studies published between 2003 and 2015 of 4568 working adults were included. All 26 studies were presented qualitatively, and 21 studies with a control group without any intervention were included in the meta-analysis. The pooled intervention effect showed a significant workplace sitting reduction of -39.6 min/8-h workday (95% confidence interval [CI]: -51.7, -27.5), favouring the intervention group. Multi-component interventions reported the greatest workplace sitting reduction (-88.8 min/8-h workday; 95% CI: -132.7, -44.9), followed by environmental (-72.8 min/8-h workday; 95% CI: -104.9, -40.6) and educational/behavioural strategies -15.5 min/8-h workday (95% CI:-22.9,-8.2). Our study found consistent evidence for intervention effectiveness in reducing workplace sitting, particularly for multi-component and environmental strategies. Methodologically rigorous studies using standardized and objectively determined outcomes are warranted. © 2016 World Obesity.


Assuntos
Local de Trabalho , Comportamento , Humanos , Saúde Ocupacional , Fatores de Tempo
3.
Occup Med (Lond) ; 64(4): 235-45, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24850815

RESUMO

BACKGROUND: Mental health is an important issue in the working population. Interventions to improve mental health have included physical activity. AIMS: To review evidence for the effectiveness of workplace physical activity interventions on mental health outcomes. METHODS: A literature search was conducted for studies published between 1990 and August 2013. Inclusion criteria were physical activity trials, working populations and mental health outcomes. Study quality was assessed using the Jadad scale. RESULTS: Of 3684 unique articles identified, 17 met all selection criteria, including 13 randomized controlled trials, 2 comparison trials and 2 controlled trials. Studies were grouped into two key intervention areas: physical activity and yoga exercise. Of eight high-quality trials, two provided strong evidence for a reduction in anxiety, one reported moderate evidence for an improvement in depression symptoms and one provided limited evidence on relieving stress. The remaining trials did not provide evidence on improved mental well-being. CONCLUSIONS: Workplace physical activity and yoga programmes are associated with a significant reduction in depressive symptoms and anxiety, respectively. Their impact on stress relief is less conclusive.


Assuntos
Ansiedade/prevenção & controle , Depressão/prevenção & controle , Exercício Físico , Saúde Mental , Estresse Psicológico/prevenção & controle , Yoga , Humanos , Transtornos Mentais/prevenção & controle , Local de Trabalho
4.
Oncogene ; 30(2): 234-44, 2011 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-20871632

RESUMO

The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase family and have been implicated in tumorigenesis. One isoform in particular, JNK2α, has been shown to be frequently activated in primary brain tumors, to enhance several tumorigenic phenotypes and to increase tumor formation in mice. As JNK is frequently activated in non-small cell lung carcinoma (NSCLC), we investigated the role of the JNK2α isoform in NSCLC formation by examining its expression in primary tumors and by modulating its expression in cultured cell lines. We discovered that 60% of the tested primary NSCLC tumors had three-fold higher JNK2 protein and two- to three-fold higher JNK2α mRNA expression than normal lung control tissue. To determine the importance of JNK2α in NSCLC progression, we reduced JNK2α expression in multiple NSCLC cell lines using short hairpin RNA. Cell lines deficient in JNK2α had decreased cellular growth and anchorage-independent growth, and the tumors were four-fold smaller in mass. To elucidate the mechanism by which JNK2α induces NSCLC growth, we analyzed the JNK substrate, signal transducer and activator of transcription 3 (STAT3). Our data demonstrates for the first time that JNK2α can regulate the transcriptional activity of STAT3 by phosphorylating the Ser727 residue, thereby regulating the expression of oncogenic genes, such as c-Myc. Furthermore, reintroduction of JNK2α2 or STAT3 restored the tumorigenicity of the NSCLC cells, demonstrating that JNK2α is important for NSCLC progression. Our studies reveal a novel mechanism in which phosphorylation of STAT3 is mediated by a constitutively active JNK2 isoform, JNK2α.


Assuntos
Adenocarcinoma Bronquioloalveolar/enzimologia , Carcinoma Pulmonar de Células não Pequenas/enzimologia , Carcinoma de Células Escamosas/enzimologia , Transformação Celular Neoplásica/metabolismo , Neoplasias Pulmonares/enzimologia , Proteína Quinase 9 Ativada por Mitógeno/metabolismo , Idoso , Idoso de 80 Anos ou mais , Animais , Linhagem Celular Tumoral , Feminino , Humanos , Isoenzimas/metabolismo , Pulmão/enzimologia , Masculino , Camundongos , Camundongos SCID , Pessoa de Meia-Idade , Proteína Quinase 9 Ativada por Mitógeno/análise , RNA Interferente Pequeno/farmacologia , Fator de Transcrição STAT3/metabolismo
5.
Am J Transplant ; 6(7): 1609-16, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16827861

RESUMO

Mycophenolate mofetil (MMF) used in a triple-drug regimen has been shown to decrease acute rejection rates, compared to a double-drug regimen. The impact of MMF on late acute rejection (LAR) episodes has not been well described. To investigate the risk of LAR (rejection > or = 6 months post-transplantation) data from the Scientific Registry of Transplant Recipients (SRTR) were used. We studied adult primary liver transplant recipients transplanted between June 1, 1995, and April 30, 2004, with hepatitis C virus (HCV) (n = 3356), hepatitis B virus (HBV) (n = 550) or a nonviral (n = 5740) primary cause of liver disease who were recorded as receiving continuous 3-(MMF + Tacro + steroids) versus 2-drug (Tacro + steroids) therapy for at least 6 months immediately post transplantation. Kaplan-Meier analysis showed significantly lower LAR rates 4 years post-transplant in 3- versus 2-drug HCV, HBV and nonviral disease patients. Multivariate regression confirmed 3- versus 2-drug therapy to be associated with a decreased risk of LAR. Late graft survival was significantly lower at 4 years post-transplant for patients with LAR 6-12 months post-transplantation versus patients with early rejection (78.0% vs. 87.0%, p < 0.001) and no rejection (88.1%, p < 0.001). Three-drug versus 2-drug therapy for a minimum of 6 months may offer a better treatment strategy to avoid the consequences and expense of LAR episodes.


Assuntos
Rejeição de Enxerto/patologia , Rejeição de Enxerto/prevenção & controle , Transplante de Fígado , Ácido Micofenólico/análogos & derivados , Doença Aguda , Adolescente , Adulto , Idoso , Feminino , Seguimentos , Rejeição de Enxerto/imunologia , Hepacivirus/efeitos dos fármacos , Hepacivirus/fisiologia , Hepatite B/tratamento farmacológico , Hepatite B/imunologia , Hepatite B/cirurgia , Hepatite B/virologia , Vírus da Hepatite B/efeitos dos fármacos , Vírus da Hepatite B/fisiologia , Hepatite C/tratamento farmacológico , Hepatite C/imunologia , Hepatite C/cirurgia , Hepatite C/virologia , Humanos , Transplante de Fígado/imunologia , Masculino , Pessoa de Meia-Idade , Ácido Micofenólico/farmacologia , Fatores de Risco , Fatores de Tempo
6.
Am J Transplant ; 5(12): 2961-7, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16303011

RESUMO

Immunosuppression is often incriminated for the increased risk of post-transplant malignancies. To examine whether triple- (MMF+Tacro+CS) versus dual-drug therapy (Tacro+CS) is associated with an increased incidence of malignancy, or death due to malignancy, data from a large registry of liver transplant recipients were analyzed. Data from adult primary liver recipients reported to the Scientific Registry of Transplant Recipients between June 1, 1995, and April 30, 2004, and recorded at transplant on triple-drug (n = 9180) or dual-drug (n = 10 099) therapy were included. Kaplan-Meier survival analysis showed no significant differences in death due to malignancy 4 years post-transplantation between the treatment groups. Multivariable analysis using Cox proportional hazard models confirmed no differences in risk of death due to malignancy between the groups (HR: 0.83, p = 0.107). Incidence of any post-transplant malignancy was also not significantly different. Older recipient age and cause of liver disease were significantly associated with an increased risk of malignancy-related death. These data utilizing relatively short follow-up suggest the addition of MMF to Tacro+CS at transplant is not associated with death due to malignancy, at least in the short term. Individual recipient factors appear to be important risk factors for malignancy-related death; elucidating these risk factors can assist in identifying who should be monitored most aggressively for post-transplant malignancies.


Assuntos
Corticosteroides/administração & dosagem , Rejeição de Enxerto/tratamento farmacológico , Imunossupressores/administração & dosagem , Transplante de Fígado/mortalidade , Ácido Micofenólico/análogos & derivados , Tacrolimo/administração & dosagem , Adolescente , Adulto , Idoso , Quimioterapia Combinada , Feminino , Rejeição de Enxerto/mortalidade , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Ácido Micofenólico/administração & dosagem , Neoplasias/mortalidade , Sistema de Registros/estatística & dados numéricos , Fatores de Risco , Análise de Sobrevida
7.
Clin Transplant ; 19(3): 340-5, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15877795

RESUMO

The present study investigated the safety of induction therapy with daclizumab (compared with no induction treatment), in adult renal transplant patients reported to the Scientific Registry of Transplant Recipients (SRTR) database between January 1, 1998 and July 27, 2003. Patients who were discharged from the hospital on mycophenolate mofetil, azathioprine, or sirolimus were divided into two groups: induction treatment with daclizumab (n = 8203) and no induction treatment (n = 25,368). Patient survival, death due to infection and death due to malignancy were evaluated at 1 and 3 yr post-transplantation. Rejection and graft survival were also examined. Kaplan-Meier and Cox regression models were used to evaluate outcomes. No significant differences were found between patients treated with daclizumab compared with patients who received no induction therapy for death due to infection or malignancy at 1 and 3 yr post-transplantation. Patients treated with daclizumab (compared with no induction treatment) had statistically significantly better survival rates at 1 (96.9% vs. 96.2%, p = 0.003) and 3 yr (92.4% vs. 91.4%, p = 0.004) although absolute differences were minimal. This was confirmed in the multivariable Cox regression analysis for patient death at 1 (HR = 0.77, p < 0.001) and 3 yr (HR = 0.83, p = 0.001) post-transplantation. Patients treated with daclizumab compared to no induction had lower rejection rates at 1 (13.1% vs. 17.3%, p < 0.001) and 3 yr post-transplantation (16.7% vs. 21.3%, p < 0.001). Cox regression confirmed a decreased risk for rejection at 1 (HR = 0.74, p < 0.001) and 3 yr (HR = 0.75, p < 0.001). Treatment with daclizumab was associated with reduced risk for graft loss at 1 (HR = 0.82, p < 0.001) and 3 years (HR = 0.86, p < 0.001). In conclusion, daclizumab was associated with a significantly reduced risk for rejection and graft loss compared with no induction treatment, and improved patient survival. In addition, daclizumab was not associated with an increase in risk of death due to infection or malignancy, when compared with no induction therapy. These findings demonstrate the short and long-term safety and efficacy of daclizumab in patients transplanted between January 1998 and July 2003.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Rejeição de Enxerto/prevenção & controle , Imunoglobulina G/uso terapêutico , Imunossupressores/uso terapêutico , Transplante de Rim/imunologia , Adulto , Anticorpos Monoclonais Humanizados , Daclizumabe , Feminino , Humanos , Transplante de Rim/mortalidade , Masculino , Pessoa de Meia-Idade , Análise de Sobrevida
8.
Transplant Proc ; 37(2): 1333-9, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15848713

RESUMO

BACKGROUND: Sparse published data exist on outcomes in daclizumab-treated cardiac transplant patients. One trial observed an increased mortality risk 6 and 12 months posttransplant in patients receiving daclizumab plus mycophenolate mofetil (MMF), cyclosporine, and steroids. This study further investigates the safety profile of daclizumab with this same immunosuppressive regimen from a large registry. METHODS: Data obtained at hospital discharge on all adult cardiac transplants performed in the USA between January 1998 and October 2003 for patients receiving MMF plus cyclosporine and steroids were accessed from the Scientific Registry of Transplant Recipients. Patients were selected based on induction treatment: daclizumab (n = 684) or no induction (n = 2525). Outcomes were evaluated at 6 months, 12 months, and 3 years posttransplant. Univariate Kaplan-Meier and multivariate Cox models were used to evaluate the effect of treatment on outcomes. Patient survival and infectious death were the primary endpoints. Secondary endpoints included rejection within the first year posttransplant (acute rejection; AR) and total rejection episodes over time. The two treatment groups shared similar demographics and transplant procedure details. RESULTS: Daclizumab (vs no induction) patients had no increased risk of patient death nor infectious death. Daclizumab patients had a lower incidence of AR at 6 months (P = .005) and 12 months (P < .001); the adjusted risk for AR at 12 months (hazards ratio [HR] = 0.77; P = .89) and over 3 years (HR 0.83, P = .006) was also lower in daclizumab-treated patients. CONCLUSIONS: In cardiac transplant patients, daclizumab (vs no induction) does not result in increased mortality or infectious death, and is associated with a lower incidence of AR.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Rejeição de Enxerto/prevenção & controle , Transplante de Coração/imunologia , Imunoglobulina G/uso terapêutico , Imunossupressores/uso terapêutico , Adulto , Anticorpos Monoclonais Humanizados , Daclizumabe , Quimioterapia Combinada , Feminino , Rejeição de Enxerto/epidemiologia , Transplante de Coração/mortalidade , Humanos , Incidência , Infecções/epidemiologia , Infecções/mortalidade , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Complicações Pós-Operatórias/classificação , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/mortalidade , Sistema de Registros , Análise de Sobrevida , Fatores de Tempo , Estados Unidos
9.
J Biol Chem ; 276(20): 17083-91, 2001 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-11278750

RESUMO

Retinoic acid (RA), a derivative of vitamin A, is essential for the normal patterning and neurogenesis during development. RA treatment induces growth arrest and terminal differentiation of a human embryonal carcinoma cell line (NT2) into postmitotic central nervous system neurons. Using RNA fingerprinting by arbitrarily primed polymerase chain reaction, we identified a novel serine/threonine-rich protein, RA-regulated nuclear matrix-associated protein (Ramp), that was down-regulated during the RA-induced differentiation of NT2 cells. Prominent mRNA expression of ramp could be detected in adult placenta and testis as well as in all human fetal tissues examined. The genomic clone of ramp has been mapped to the telomere of chromosome arm 1q, corresponding to band 1q32.1-32.2. Associated with the nuclear matrix of NT2 cells, Ramp translocates from the interphase nucleus to the metaphase cytoplasm during mitosis. During the late stage of cytokinesis, Ramp concentrates at the midzone of the dividing daughter cells. The transcript expression of ramp is closely correlated with the cell proliferation rate of NT2 cells. Moreover, overexpression of Ramp induces a transient increase in the proliferation rate of NT2 cells. Taken together, our data suggest that Ramp plays a role in the proliferation of the human embryonal carcinoma cells.


Assuntos
Regulação da Expressão Gênica/fisiologia , Neurônios/fisiologia , Matriz Nuclear/metabolismo , Proteínas Nucleares/genética , Transcrição Gênica , Tretinoína/farmacologia , Adulto , Fosfatase Alcalina/genética , Sequência de Aminoácidos , Carcinoma Embrionário , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Clonagem Molecular , Embrião de Mamíferos , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Biblioteca Gênica , Humanos , Masculino , Dados de Sequência Molecular , Neurônios/citologia , Neurônios/efeitos dos fármacos , Especificidade de Órgãos , Placenta/metabolismo , Gravidez , Regiões Promotoras Genéticas , Conformação Proteica , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica/efeitos dos fármacos , Células Tumorais Cultivadas , Ubiquitina-Proteína Ligases
10.
Eur J Neurosci ; 11(2): 373-82, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10051737

RESUMO

A muscle-specific receptor tyrosine kinase, designated MuSK, mediates agrin-induced aggregation of acetylcholine receptors at the vertebrate neuromuscular junction. cDNAs encoding Xenopus MuSK were isolated from embryonic cDNA libraries. The full-length MuSK cDNA encodes for a polypeptide of 948 amino acids and possesses the features unique to mammalian MuSK, including four Ig-like domains, C6 box, transmembrane region and an intracellular tyrosine kinase domain. Interestingly, Xenopus MuSK also contains a kringle domain similar to that previously reported for Torpedo MuSK. The overall amino acid sequence identity of Xenopus MuSK with mammalian MuSK is approximately 65%. Northern blot analysis demonstrated the presence of three MuSK transcripts (approximately 1 kb, approximately 3 kb and approximately 7 kb) which were differentially expressed during development. The expression of the approximately 7 kb MuSK transcript remained as the predominant species in adult tissues, e.g. skeletal muscle, spleen and lung. Immunocytochemical analysis with a MuSK-specific antibody revealed that Xenopus MuSK was colocalized with AChRs at neuromuscular junctions as well as in spontaneous acetylcholine receptor hot spots of cultured muscle cells. In situ hybridization revealed prominent expression of MuSK transcripts in neural tissues and myotomal muscle during the period of neurulation and synaptogenesis. The MuSK transcript detected at abundant levels in the central nervous system (CNS) was localized to the brain, spinal cord and eye vesicles during early embryonic development. In addition, the MuSK protein in the developing eye was found to be prominently expressed during embryonic stages of 32 and 35. These findings raise an intriguing possibility that, in addition to the known function in the formation of the neuromuscular junctions, MuSK may be involved in neural development.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Músculo Esquelético/enzimologia , Receptores Proteína Tirosina Quinases/genética , Agrina/fisiologia , Animais , Northern Blotting , Células Cultivadas , Embrião de Galinha , Clonagem Molecular , DNA Complementar , Hibridização In Situ , Larva/enzimologia , Larva/crescimento & desenvolvimento , Dados de Sequência Molecular , Neurônios Motores/química , Neurônios Motores/citologia , Neurônios Motores/fisiologia , Desenvolvimento Muscular , Fibras Musculares Esqueléticas/química , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/citologia , Músculo Esquelético/crescimento & desenvolvimento , Junção Neuromuscular/química , Junção Neuromuscular/enzimologia , Junção Neuromuscular/crescimento & desenvolvimento , Estrutura Terciária de Proteína , RNA Mensageiro/análise , Receptores Proteína Tirosina Quinases/química , Receptores Colinérgicos/análise , Homologia de Sequência de Aminoácidos , Xenopus laevis
11.
J Neurochem ; 68(5): 1882-8, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9109513

RESUMO

Retinoic acid (RA) induced the terminal differentiation of a human embryonal carcinoma cell line (NT2/D1) into several morphologically distinct cell types, including the postmitotic CNS neurons. Although RA has been suggested to play an important role in brain development, little is known about the molecular mechanism by which RA induces neuronal differentiation. In the present study, RNA fingerprinting by arbitrarily primed PCR (RAP-PCR) was used to identify the transcripts in NT2/D1 cells that were differentially regulated by RA. Northern blot analysis of the differentially amplified PCR fragments revealed 11 genes that were regulated by RA. Of these, seven were up-regulated and four were down-regulated along the course of RA treatment. More importantly, four of the RA-regulated genes that were identified in the present study are novel. Our findings suggested that there are a number of RA-regulated genes that have yet to be identified. RAP-PCR provides a useful tool for studying the patterns of transcript expression during the course of RA treatment and allows the cloning of novel genes involved in the process of neuronal differentiation. Furthermore, it provides a basis for the selection of genes that are involved in the RA-induced signaling pathway in the human CNS.


Assuntos
Carcinoma Embrionário/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Genes , Tretinoína/farmacologia , Northern Blotting , Diferenciação Celular , Fragmentação do DNA , DNA Complementar/metabolismo , Técnicas Genéticas , Humanos , Neurônios/patologia , Reação em Cadeia da Polimerase , RNA Neoplásico/genética , Células Tumorais Cultivadas/efeitos dos fármacos
12.
Neuroreport ; 7(6): 1204-8, 1996 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-8817533

RESUMO

Retinoic acid induced the differentiation of human embryonal carcinoma cells (NT2/D1) into several morphologically distinct cell types, including those resembling terminally differentiated postmitotic CNS neurones. The mechanism by which retinoic acid influences the process of neuronal differentiation in the CNS, however, remains unknown. In the present study, we have examined the ability of retinoic acid to induce the expression of the receptors that mediate the actions of the neurotrophins, using reverse transcription-polymerase chain reaction and Northern blot analysis. Our study demonstrated that the expression of mRNAs for three human trk receptors was significantly induced after treatment with retinoic acid. These findings suggest that the actions of retinoic acid on neuronal differentiation in the human CNS may potentially be mediated by the neurotrophins.


Assuntos
Antineoplásicos/farmacologia , Carcinoma Embrionário/tratamento farmacológico , Fatores de Crescimento Neural/fisiologia , Receptores Proteína Tirosina Quinases/efeitos dos fármacos , Tretinoína/farmacologia , Carcinoma Embrionário/metabolismo , Diferenciação Celular/efeitos dos fármacos , Indução Enzimática , Humanos , Immunoblotting/métodos , Reação em Cadeia da Polimerase/métodos , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Receptores Proteína Tirosina Quinases/biossíntese , Receptor do Fator Neutrófico Ciliar , Receptor trkA , Receptor trkC , Receptores de Fator de Crescimento Neural/efeitos dos fármacos , Transcrição Gênica , Células Tumorais Cultivadas
13.
Arch Biochem Biophys ; 234(1): 129-37, 1984 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-6548352

RESUMO

The effects of human serum albumin (HSA) on the rate of dithionite reduction of iron(III)deuteroporphyrin (iron(III)Dp) have been investigated in order to further characterize the porphyrin binding site and the changes manifested in this site under various conditions. These studies were performed under pseudo-first-order conditions, and in the presence of carbon monoxide as a "trapping agent" for the reduced iron(II)porphyrin. The rate of reduction of the free iron(III)Dp in phosphate buffer at pH 7.4 follows second-order kinetics with a rate constant (4.2 X 10(9) M-1 s-1) suggestive of a diffusion-controlled process. A six-orders of magnitude decrease in the rate of reduction was observed with iron(III)Dp was complexed with HSA. This result is consistent with HSA-bound porphyrin being less accessible to the aqueous environment. Additional studies demonstrated that both pH and anions induce various alterations in the complex that are reflected in the rate of reduction of iron(III)porphyrin.


Assuntos
Deuteroporfirinas , Ditionita , Compostos Férricos , Ferro , Porfirinas , Albumina Sérica , Sulfitos , Sítios de Ligação , Fenômenos Químicos , Química , Humanos , Cinética , Ligantes , Modelos Químicos , Oxirredução , Ligação Proteica , Conformação Proteica , Espectrofotometria
14.
Hemoglobin ; 7(2): 141-57, 1983.
Artigo em Inglês | MEDLINE | ID: mdl-6423574

RESUMO

We have studied the mutual effects of chloride ion and EDTA on the dimer-tetramer assembly of human deoxyhemoglobin and oxyhemoglobin. It is found that these two anions have similar but interdependent effects. In low C1- (.01 M) increasing concentrations of EDTA are found to decrease both forward and reverse rate constants for deoxyhemoglobin, whereas no effect is observed at 0.1 M C1-. These results suggest that binding of anions at the alpha 1 beta 2 intersubunit contact may stabilize both the dimeric and tetrameric forms of the deoxy molecule, thus inhibiting both the dissociation and reassociation reactions. The overall effects of EDTA and low C1- on the dimer-tetramer equilibrium constants are found to be distinctly different in deoxy and oxyhemoglobins with a major effect on the oxy form. These findings establish validity of the results from previous thermodynamic studies carried out in approximately physiological C1- concentrations along with the small amounts of EDTA which are used to minimize artifacts of oxidation. As observed for deoxyhemoglobin, it is found that in 0.1 M C1- ion there is no further effect of EDTA on the oxyhemoglobin dimer-tetramer equilibrium.


Assuntos
Cloretos/farmacologia , Ácido Edético/farmacologia , Hemoglobinas/análise , Oxiemoglobinas/análise , Adulto , Humanos , Técnicas In Vitro , Ligantes
15.
J Biol Chem ; 256(3): 1199-205, 1981 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-7451499

RESUMO

The dimer-tetramer equilibrium constants of human oxyhemoglobin (4K2) and deoxyhemoglobin (0K2) have been determined at 21.5 degrees C as a function of pH and chloride concentration. In buffers containing 0.1 M NaCl, 1 mM EDTA, the apparent numbers of protons released upon assembly of dimers into tetramers were determined from the pH dependencies of 4K2 and 0K2. At pH 7.4, the assembly of unliganded tetramers is accompanied by the absorption of 0.9 +/- 0.1 mol of H+. For assenbly of oxyhemoglobin, there are 0.8 +/- 0.1 mol of H+ released per mol of tetramer formed. From these results and the value of 2.1 mol of H+/402 for the tetramer Bohr effect, a Bohr effect for dimers is determined as 0.2 +/- .08 mol of H+ released upon binding 2 mol of 02. Thus, the dimer Bohr effect is approximately 20% as large as the tetramer Bohr effect. At pH 7.4, the value of 0K2 is insensitive to [Cl-], whereas 4K2 varies inversely with [Cl-]. At pH 8.95, both 4K2 and 0K2 decrease with increasing [Cl-]. These and previous results indicate that salt bridges are not the dominant energetic factor in stabilizing the deoxy quaternary structure of hemoglobin. In buffer conditions of 0.1 M Tris-HCl, 0.1 M NaCl, 1 mM EDTA, pH 7.4, we estimate 1.8 mol of Cl- bound upon dissociation of 1 mol of oxy tetramers into oxy dimers, whereas the deoxy molecules dissociate without any change in bound chloride. From the [Cl-] dependence of oxygenation curves, we estimate 1.8 mol of [Cl-] released upon binding 4 mol of O2 to tetramers. Thus, oxygenation of dimers at pH 7.4 apparently involves no change in bound chloride.


Assuntos
Oxigênio/sangue , Oxiemoglobinas/metabolismo , Cloreto de Sódio , Cloretos , Haptoglobinas , Humanos , Concentração de Íons de Hidrogênio , Cinética , Substâncias Macromoleculares
16.
J Biol Chem ; 254(10): 3772-6, 1979 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-438158

RESUMO

The reaction of apohemoglobin with carbonmonoxy heme and with carbonmonoxy heme dimethyl ester was investigated in the presence and absence of inositol hexaphosphate. The binding stoichiometry of both heme derivatives to apohemoglobin was not affected by the presence of the polyphosphate, while, in both cases, the overall rate of recombination was substantially decreased. The absence of the negatively charged carboxyl groups in the dimethyl ester derivative of the heme indicated that the effect of inositol hexaphosphate on the reaction of apohemoglobin with heme was not due to electrostatic repulsions and resulted from conformational changes occurring upon the interaction of apohemoglobin with inositol hexaphosphate. Qualitative treatment of the kinetic data suggests that these conformational changes destabilize the intermediates of the reaction by increasing their redissociation into the original components. Also, benzenehexacarboxylate produced conformational changes in apohemoglobin and decreased its rate of reaction with carbonmonoxy heme, proving the aspecificity of the interaction of apohemoglobin with polyanions.


Assuntos
Monóxido de Carbono , Heme , Hemoglobinas , Ácido Fítico , Apoproteínas , Humanos , Cinética , Ligação Proteica
17.
J Biol Chem ; 254(2): 371-6, 1979 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-762065

RESUMO

Experiments of sedimentation velocity and equilibrium indicate that in the presence of inositol hexaphosphate the degree of polymerization of apohemoglobin is shifted in favor of the formation of tetramers, with a maximum effect when the concentration of the polyphosphate is 1 mM. Above this concentration, a redissociation of the system into dimers is promoted. This phenomenon is probably due to the binding of inositol hexaphosphate to apohemoglobin with a stoichiometry higher than 1 mol of polyphosphate/4 subunits. The optical rotatory dispersion spectrum of apohemoglobin is also modified by its interaction with inositol hexaphosphate suggesting a small increase in the helical content of the protein. Measurements of circular dichroism in the near-UV region of the spectrum indicate that the environment of the aromatic chromophores of the protein such as tyrosine, phenyalanine, and tryptophan is not affected by the interaction. The presence of inositol hexaphosphate decreases the rate of reaction of the beta-93 cysteinyl residues of apohemoglobin with both p-mercuribenzoate and N-ethylmaleimide, suggesting a conformational change of the protein also at the level of its tertiary structure.


Assuntos
Apoproteínas , Hemoglobinas , Ácido Fítico , Dicroísmo Circular , Etilmaleimida , Humanos , Cinética , Substâncias Macromoleculares , Matemática , Dispersão Óptica Rotatória , Ligação Proteica , Conformação Proteica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA