Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Front Immunol ; 10: 2618, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31803180

RESUMO

Adult-onset primary immunodeficiency is characterized by recurrent infections, hypogammaglobulinemia, and poor antibody response to vaccines. In this study, we have analyzed targeted gene panel sequencing results of 270 patients diagnosed with antibody deficiency and identified five disease-associated variants in NFKB1 in five unrelated families. We detected two single base pair deletions and two single base pair insertions, causing severe protein truncations, and one missense mutation. Immunoblotting, lymphocyte stimulation, immunophenotyping, and ectopic expression assays demonstrated the functional relevance of NFKB1 mutations. Besides antibody deficiency, clinical manifestations included infections, autoimmune features, lymphoproliferation, lymphoma, Addison's disease, type 2 diabetes and asthma. Although partial clinical penetrance was observed in almost all pedigrees, all carriers presented a deficiency in certain serum immunoglobulins and the majority showed a lack of memory B cells (CD19+CD27+). Among all tested genes, NFKB1 alterations were the most common monoallelic cause of antibody deficiency in our cohort.

2.
Clin Immunol ; 210: 108269, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31683054

RESUMO

Genetic studies have led to identification of an increasing number of monogenic primary immunodeficiency disorders. Monoallelic pathogenic gain-of-function (GOF) variants in NFKBIA, the gene encoding IκBα, result in an immunodeficiency disorder, typically accompanied by anhidrotic ectodermal dysplasia (EDA). So far, 14 patients with immunodeficiency due to NFKBIA GOF mutations have been reported. In this study we report three patients from the same family with immunodeficiency, presenting with recurrent respiratory tract infections, bronchiectasis and viral skin conditions due to a novel pathogenic NFKBIA variant (c.106 T > G, p.Ser36Ala), which results in reduced IκBα degradation. Immunological investigations revealed inadequate antibody responses against vaccine antigens, despite hypergammaglobulinemia. Interestingly, none of the studied patients displayed features of EDA. Therefore, missense NFKBIA variants substituting serine 36 of IκBα, differ from the rest of pathogenic GOF NFKBIA variants in that they cause combined immunodeficiency, even in the absence of EDA.

4.
Nephrol Dial Transplant ; 33(6): 1065-1072, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29444269

RESUMO

Background: We analysed in a carefully phenotyped cohort of paediatric patients the association of serum angiotensin II type 1 receptor antibodies (AT1R-Ab) with specific histological lesions and with graft function and survival in conjunction with overall and complement-binding donor-specific human leucocyte antigen donor-specific antibodies (HLA-DSA). Methods: Sera of 62 patients at the time of renal graft biopsy for clinical indication >1 year post-transplant were assessed for AT1R-Ab by enzyme-linked immunosorbent assay (ELISA) and for DSA and C1q-fixing DSA by single-antigen bead technology. Results: Serum AT1R-Ab concentration was significantly higher in antibody-mediated rejection (ABMR) than in T-cell-mediated rejection or control. By receiver operating characteristic (ROC) curve analysis, the optimal AT1R-Ab cut-off value discriminating between patients with features of ABMR and those without was 9.5 U/mL. A total of 6 of 28 patients (21.4%) with ABMR were only positive for AT1R-Ab. Patients with AT1R-Ab and HLA-DSA double positivity had a significantly higher vascular micro-inflammation score than DSA-negative patients. The 5-year graft survival was only 59% in the AT1R-Ab-positive group compared with 87% in the AT1R-Ab-negative group. Patients with AT1R-Ab and HLA-DSA double positivity tended to have a more rapid decline of estimated glomerular filtration rate (eGFR) than patients who were only positive for AT1R-Ab or HLA-DSA. In a multivariate Cox regression model of non-invasive factors, C1q-positive HLA-DSA, eGFR and AT1R-Ab positivity were significantly associated with accelerated graft function decline. Conclusions: Serum AT1R-Ab positivity in the context of an indication biopsy >1 year post-transplant is associated with the histopathology of ABMR and is an independent non-invasive risk factor for adverse graft outcome.


Assuntos
Anticorpos/efeitos adversos , Rejeição de Enxerto/mortalidade , Sobrevivência de Enxerto , Antígenos HLA/imunologia , Transplante de Rim/efeitos adversos , Receptor Tipo 1 de Angiotensina/imunologia , Transplantados/estatística & dados numéricos , Adolescente , Adulto , Anticorpos/imunologia , Criança , Feminino , Taxa de Filtração Glomerular , Rejeição de Enxerto/etiologia , Rejeição de Enxerto/patologia , Humanos , Masculino , Receptor Tipo 1 de Angiotensina/sangue , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Taxa de Sobrevida , Doadores de Tecidos
6.
Clin Immunol ; 179: 1-7, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28216420

RESUMO

Here we describe novel mutations in recombination activation gene 1 (RAG1) in a compound heterozygous male patient with combined T and B cell immunodeficiency (CID). Clinical manifestations besides antibody deficiency included airway infections, granulomatosis and autoimmune features. He died at the age of 37 due to PML caused by JC virus infection. By targeted next-generation sequencing we detected post mortem in this patient three mutations in RAG1. One allele harbored two novel mutations (c.1123C>G, p.H375D and c.1430delC, p.F478Sfs*14), namely a missense variant and a frameshift deletion, of which the latter leads to a truncated RAG1 protein. The other allele revealed a previously described missense mutation (c.1420C>T, p.R474C, rs199474678). Functional analysis of the p.R474C variant in an in vitro V(D)J recombination assay exhibited reduced recombination activity compared to a wild-type control. Our findings suggest that mutations in RAG1, specifically the p.R474C variant, can be associated with relatively mild clinical symptoms or delayed occurrence of T cell and B cell deficiencies but may predispose to PML.


Assuntos
Proteínas de Homeodomínio/genética , Síndromes de Imunodeficiência/genética , Leucoencefalopatia Multifocal Progressiva/genética , Adulto , Linfócitos B/imunologia , Biópsia , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Proliferação de Células , Humanos , Imunoglobulinas/sangue , Síndromes de Imunodeficiência/sangue , Síndromes de Imunodeficiência/diagnóstico por imagem , Síndromes de Imunodeficiência/imunologia , Leucoencefalopatia Multifocal Progressiva/sangue , Leucoencefalopatia Multifocal Progressiva/diagnóstico por imagem , Leucoencefalopatia Multifocal Progressiva/imunologia , Contagem de Linfócitos , Imagem por Ressonância Magnética , Masculino , Mutação , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/imunologia , Recombinação V(D)J
7.
Sci Total Environ ; 573: 1370-1379, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27436779

RESUMO

The implementation of quality control procedures in analytical laboratories around the world has become essential in order to ensure the quality and safety of food. This article describes the procedure adopted by the Brazilian government in order to achieve this goal, specifically in the area of analysis of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The validation of a multiresidue method, the calculation of measurement uncertainty, and the quality control procedure adopted in the determination of these compounds in beef cattle fat were performed as set out in national legislation (Brasil, 2011), which is aligned with international guidelines. Evaluation was made of selectivity, linearity, precision (repeatability and reproducibility), accuracy, and limits of detection and quantification. Stability studies were also undertaken. The technique was extended to three other matrices (poultry, horse, and pig adipose tissues), with evaluation of matrix effects, selectivity, linearity, and accuracy. The analyses were performed by gas chromatography with electron capture detection (GC-ECD) and mass spectrometric detection (GC-MS). In recent years, analyses conducted under the National Plan for Control of Residues and Contaminants (PNCRC) have shown no exceedances of the maximum permitted residue levels (MRLs) of pesticides and PCBs in these tissues, as observed in other countries that carry out effective monitoring of these contaminants.


Assuntos
Tecido Adiposo/química , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Contaminação de Alimentos/análise , Carne/análise , Compostos Orgânicos/análise , Animais , Brasil , Bovinos , Cavalos , Praguicidas/análise , Bifenilos Policlorados/análise , Aves Domésticas , Sus scrofa
8.
J Ultrasound Med ; 35(7): 1593-9, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27335443

RESUMO

Six patients with 7 lesions that were histologically confirmed as primary testicular lymphoma were preoperatively investigated with a standardized sonographic protocol including contrast-enhanced sonography. Duplex and contrast-enhanced sonography showed marked hypervascularization in all 7 lesions. On contrast-enhanced sonography, the filling time of lymphomatous lesions was significantly shorter than the filling time of a size-matched sample of 10 patients with seminomas (P < .0001). The sonographic hallmarks of testicular lymphoma in our case series were as follows: (1) sharply demarcated homogeneous hypoechoic testicular lesions with marked hypervascularization; (2) a rapid (<7 seconds) filling time of contrast bubbles; and (3) a straight and parallel course of intralesional vessels on contrast-enhanced sonography.


Assuntos
Meios de Contraste/farmacocinética , Aumento da Imagem/métodos , Linfoma/diagnóstico por imagem , Fosfolipídeos/farmacocinética , Hexafluoreto de Enxofre/farmacocinética , Neoplasias Testiculares/diagnóstico por imagem , Ultrassonografia/métodos , Idoso , Diagnóstico Diferencial , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Testiculares/irrigação sanguínea , Testículo/irrigação sanguínea , Testículo/diagnóstico por imagem , Tempo
9.
Ultrasound Med Biol ; 42(8): 1807-15, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27181687

RESUMO

This study investigates the usefulness of contrast-enhanced ultrasound (CEUS) and real-time elastography (RTE) for the characterization of testicular masses by comparing pre-operative ultrasound findings with post-operative histology. Sixty-seven patients with 68 sonographically detected testicular masses underwent B-mode, color-coded Doppler sonography (CCDS), CEUS and RTE according to defined criteria. For RTE, elasticity score (ES), difference of elasticity score (D-ES), strain ratio (SR) and size quotient (Qsize) were evaluated. Histopathologically, 54/68 testicular lesions were neoplastic (47 malignant, 7 benign). Descriptive statistics revealed the following results (neoplastic vs. non-neoplastic) for sensitivity, specificity, positive predictive value, negative predictive value and accuracy, respectively: B-mode, 100%, 43%, 87%, 100%, 88%; CCDS 81%, 86%, 96%, 55%, 82%; CEUS 93%, 85%, 96%, 73%, 91%; ES 98%, 25%, 85%, 75%, 85%; D-ES 98%, 50%, 90%, 83%, 89%; SR 90%, 45%, 86%, 56%, 81%; and Qsize 57%, 83%, 94%, 28%, 61%. B-mode with CCDS remains the standard for assessing testicular masses. In characterization of testicular lesions, CEUS clearly outperformed all other modalities. Our study does not support the routine use of RTE in testicular ultrasonography because of its low specificity.


Assuntos
Meios de Contraste , Aumento da Imagem/métodos , Fosfolipídeos , Hexafluoreto de Enxofre , Neoplasias Testiculares/diagnóstico por imagem , Ultrassonografia/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Técnicas de Imagem por Elasticidade/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade , Testículo/diagnóstico por imagem , Ultrassonografia Doppler em Cores/métodos , Adulto Jovem
10.
J Public Health (Oxf) ; 38(1): 84-91, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25665877

RESUMO

BACKGROUND: The phenomenon of waterpipe smoking (WPS) among adolescents has become eminent, and it is especially prevalent in Lebanon. Unlike cigarette smoking, WPS is parentally and socially acceptable. This study aims at examining the association between intention to smoke waterpipe in the next 6 months, and knowledge, attitudes and parental and social influences. METHODS: This is a secondary data analysis from a national survey in 2007 on 1028 households. This study addresses 258 non-smoking adolescents and their parents. Consent was sought and the study was approved by the Institutional Review Board at the American University of Beirut. Face-to-face interviews were conducted. Descriptive analysis, crude and adjusted odds ratios (ORs) were generated. RESULTS: At the bivariate level, late adolescence, mothers without university education, prior adolescents' WPS experiences, best friends' and parents' WPS habits and adolescents' and parents' lower attitude scores were associated with smoking intention. In the adjusted model, adolescents' beliefs about positive effects, best friends' similar habits and prior smoking remained significant (respective ORs [95% confidence interval ]: 1.81 [1.33-2.45], 2.51 [1.24-5.10], 4.91 [2.35-10.36]). Parents' perceived attitude against smoking was protective (OR: 0.57 [0.39-0.83]). CONCLUSIONS: Adolescents' intention to smoke is highly influenced by parents' permissive attitudes and peer pressure. Interventions targeting these two groups and limiting access to smoking by adolescents should be instigated.


Assuntos
Fumar/epidemiologia , Adolescente , Fatores Etários , Escolaridade , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Intenção , Entrevistas como Assunto , Líbano , Masculino , Pais/psicologia , Fumar/psicologia , Inquéritos e Questionários
11.
BMC Public Health ; 15: 578, 2015 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-26093501

RESUMO

BACKGROUND: Seasonal influenza is one of the most significant infectious diseases in Germany; epidemic outbreaks occur every winter and cause substantial morbidity and mortality. However, published data from Germany on the current economic burden of influenza and the costs per episode are lacking. METHODS: A retrospective database analysis was conducted using a longitudinal electronic medical records database (IMS Disease Analyzer). Patients with influenza, diagnosed by German office-based physicians using ICD-10 J09-11 (International Classification of Diseases, 10(th) revision), who were observable in the database from 12 months before the index (diagnosis) date until 1 month afterwards, were included. The selection window, defined to cover two influenza seasons, was May 2010 to April 2012. Direct and indirect costs were evaluated from payer, patient and societal perspectives. Published unit costs and tariffs from Germany (2012) were used for the analysis. RESULTS: A total of 21,039 influenza-attributable episodes in 17,836 adults, managed by primary care physicians (PCP) and 7,107 episodes in 6,288 children, managed by pediatricians, were eligible for analysis. The mean (±Standard Deviation (SD)) age of the adults with at least one episode was 46 (±18) years and 7 (±4) years in the children. The presence of clinical risk factors was documented for 39% episodes in adults and 24% episodes in children, with the most common being cardiovascular diseases in adults (29%) and chronic respiratory diseases in children (23%). Complications and severe symptoms accompanied the influenza-attributable episode (adults: 37%, children: 54%), bronchitis (adults: 16%, children: 19%) and acute upper respiratory infection (adults: 15%, children: 21%) being the most frequent. From a societal perspective, the total average mean cost (±SD) per episode was €514 (±609) in adults, where work days lost were the main cost driver (82%), and €105 (±224) in children. Complications and severe symptoms increased the cost per episode versus episodes without by 1.7 times in adults (€684 (±713) vs. €413 (±510)) and nearly 3 times in children (€149 (±278) vs. €55 (±116)). CONCLUSIONS: Based on a large patient sample derived from representative PCP and pediatricians panels, our results demonstrate that seasonal influenza is associated with substantial clinical and economic burden in Germany.


Assuntos
Bases de Dados Factuais/estatística & dados numéricos , Gastos em Saúde/estatística & dados numéricos , Influenza Humana/economia , Atenção Primária à Saúde/estatística & dados numéricos , Absenteísmo , Adolescente , Adulto , Criança , Pré-Escolar , Efeitos Psicossociais da Doença , Feminino , Alemanha/epidemiologia , Serviços de Saúde/economia , Serviços de Saúde/estatística & dados numéricos , Humanos , Influenza Humana/complicações , Classificação Internacional de Doenças , Masculino , Pessoa de Meia-Idade , Pediatria/estatística & dados numéricos , Estudos Retrospectivos , Fatores de Risco
12.
Chembiochem ; 13(7): 993-8, 2012 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-22504937

RESUMO

Diaminoterephthalates with a maleimide moiety were synthesized and used as fluorescence dyes for sensing thiols. Whereas these "NiWa Blue" dyes showed no emission, the conjugate addition of a thiol to the maleimide group turned on a fluorescence at about 400 nm when irradiating the dye at 338 nm. The neuronal-calcium sensor protein recoverin possesses a single cysteine residue at position 39, which reacts with NiWa Blue, and is therefore labeled by a fluorophore with an emission at about 440 nm. In the absence of Ca(2+), irradiation at 280 nm of a tryptophan residue in close proximity to Cys-bound NiWa Blue lead to strong FRET, which was detected by emission of the dye at 440 nm. In the presence of Ca(2+), the protein holds a conformation with distal Trp and Cys residues, thus FRET of irradiated Trp to Cys-bound NiWa Blue was significantly weakened.


Assuntos
Corantes Fluorescentes/química , Ácidos Ftálicos/química , Recoverina/química , Espectrometria de Fluorescência/métodos , Compostos de Sulfidrila/química , Cromatografia Líquida de Alta Pressão/métodos , Química Click , Conformação Proteica , Recoverina/análise , Compostos de Sulfidrila/análise
13.
J Dtsch Dermatol Ges ; 7(10): 896-8, 2009 Oct.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-19453384

RESUMO

A 52-year-old geriatric nurse presented with recurrent eczema localized in uncovered skin areas. Patch testing produced an eczematous skin reaction with type IV sensitization totetrazepam. A relapse of contact dermatitis was successfully prevented by using occupational skin protection measures and organizational measures.Our case indicates that a sensitization to drugs should be considered when allergic contact dermatitisis suspected in nursing personnel.


Assuntos
Benzodiazepinas/efeitos adversos , Dermatite Alérgica de Contato/diagnóstico , Dermatite Alérgica de Contato/etiologia , Dermatite Ocupacional/diagnóstico , Dermatite Ocupacional/etiologia , Enfermagem Geriátrica , Enfermeiras e Enfermeiros , Dermatite Alérgica de Contato/prevenção & controle , Dermatite Ocupacional/prevenção & controle , Feminino , Humanos , Pessoa de Meia-Idade
14.
J Invest Dermatol ; 128(4): 890-6, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18049454

RESUMO

Currently, most medical gloves are produced with a low content of natural rubber latex (NRL) protein. However, they may be substituted by proteins of foreign origin to maintain specific properties of the material. The aim of this study was to investigate the allergenicity and immunogenicity of unexpected proteins (i.e., soy and casein) compared with NRL proteins in a murine model in BALB/c mice. All respective allergen sources (extracts from three brands of NRL gloves, soy, and casein) were able to induce significant allergen-specific IgE and IgG(1) responses. On average, the highest IgE induction occurred after immunization with NRL, followed by soy and casein. Certain individuals from each treatment group exhibited levels of specific IgE as high as due to NRL. To analyze further specific IgE responses on a single allergen level, we established a microarray based on recombinant allergens for allergen-specific murine IgE detection. Besides specific IgE against rHev b 3, -6, -7, -8, and -11, specific IgE against kappa-casein could be detected in mice immunized with NRL glove extract, indicating a sensitization potential of the contained foreign protein. The substitution of genuine latex proteins by proteins of foreign origin may lead to a shift and de novo increase in sensitization to the finished products.


Assuntos
Alérgenos/imunologia , Luvas Cirúrgicas/efeitos adversos , Hipersensibilidade Imediata/imunologia , Imunoglobulina E/sangue , Proteínas/imunologia , Alérgenos/genética , Alérgenos/isolamento & purificação , Animais , Caseínas/imunologia , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Modelos Animais , Análise Serial de Proteínas , Proteínas/isolamento & purificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Proteínas de Soja/imunologia
15.
Anal Chem ; 79(1): 60-70, 2007 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-17194122

RESUMO

A method for simultaneous and referenced 2D mapping of pH and pO2 is described. The experimental setup combines a fast gateable CCD camera as detector, a LED as excitation light source and a single-layer sensor membrane as optical transducer. The planar optode comprises a lipophilic fluorescein derivative (lifetime approximately 5 ns) and platinum(II) mesotetrakis(pentafluorophenyl)porphyrin (approximately 70 micros in the absence of a quencher) immobilized in a hydrogel matrix. Depending on the fluorescent pH indicator, a pH transition in the physiological range (pH 6-pH 8) or in the near-basic region (pH 7-pH 9) can be achieved. The measuring scheme involves the time-resolved acquisition of images in three windows during a series of square-shaped excitation pulses. A method allowing the calculation of both parameters from these three images is presented. The pH/pO2 hybrid sensor incorporating the pH indicator 2',7'-dihexyl-5(6)-N-octadecyl-carboxamidofluorescein was characterized in detail. The pH and pO2 were determined with a maximum deviation of 0.03 pH unit and 6.5 hPa pO2, respectively, within the range of pH 7.6-pH 8.7 and 0-200 hPa pO2 in test measurements. The ionic strength (IS) cross-sensitivity was found to be relatively small (pH/IS < 3.5 x 10(-4) mM(-1) and pO2/IS <-0.053 hPa mM(-1) at a transition from 0.5 to 0.1 M IS). Whereas a strong temperature effect on the sensor signal was observed (DeltapH/DeltaT = 0.011-0.034 K-1 and DeltapO2/DeltaT = 1.85-7.17 hPa K-1 in the range from 277 to 308 K). Examples of pH/pO2 images obtained in natural marine sediment are presented.

16.
Analyst ; 130(6): 907-16, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15912240

RESUMO

In this work we present optical pH sensors especially designed for pH measurements in marine environment. Embedded in an uncharged, highly proton-permeable hydrogel matrix, the two novel lipophilic carboxyfluorescein derivatives 2',7'-dihexyl-5(6)-N-octadecyl-carboxamidofluorescein (DHFA) and 2',7'-dihexyl-5(6)-N-octadecyl-carboxamidofluorescein ethyl ester (DHFAE) have apparent dissociation constants of ca. 8.4. The pH transition range of the sensors perfectly matches the pH range occurring in seawater and marine sediment (ca. pH 7.2-9.2). The cross-sensitivity towards ionic strength (IS) was found to be low for DHFA-containing membranes and was even negligible when using DHFAE as indicator. The quantum yield (QY) of DHFA (0.94(basic)) is similar to that of fluorescein (0.97(basic)). QYs of 0.62(basic) and 0.22(acidic) were found for DHFAE. The optical properties of the indicators enable referenced measuring schemes. Lactonisation of the DHFAE chromophore is prevented by esterification of the carboxyl group in 2 position. Thus, internally referenced dual wavelength measurements are possible since the emission maxima of the basic and acidic form of DHFAE differ by 30 nm. Dual lifetime referenced (DLR) measurements were made with pH sensors incorporating ruthenium-(II)-tris-4,7-diphenyl-1,10-phenanthroline (Ru(dpp)(3))-containing reference particles in addition to the indicator. This type of sensor can be applied for pH imaging or in phase-modulation measurements of pH.


Assuntos
Concentração de Íons de Hidrogênio , Água do Mar/química , Fluoresceínas , Sedimentos Geológicos/química , Hidrogel de Polietilenoglicol-Dimetacrilato , Indicadores e Reagentes
18.
Mol Endocrinol ; 16(5): 961-76, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-11981032

RESUMO

Several cell lines, including ROS17/2.8 rat osteosarcoma (ROS) cells, contain functional VDRs and RXRs but are resistant to the antiproliferative effects of calcitriol and retinoids. We explored the role of receptor degradation in this hormone resistance. Results of transactivation assays indicated that ROS cells contain insufficient amounts of RXR to activate a DR-1 reporter, and Western blot analyses of cell extracts showed that the degradation of RXR is accelerated and produces an aberrant 45-kDa RXR. We stably expressed functional fluorescent chimeras of VDR and RXR [green fluorescent protein (GFP)-VDR; yellow fluorescent protein (YFP)-RXR] to evaluate degradation mechanisms and the impact of excess receptor expression on antiproliferative effects. Microscopy showed a diminished expression of YFP-RXR in ROS cells compared with the expression in CV-1 cells. Treatment with inhibitors of proteasomal degradation (lactacystin and MG132) selectively enhanced GFP-VDR and YFP-RXR expression and also increased the endogenous levels of VDR and RXR. Expression of GFP-VDR had no effect on the sensitivity of ROS cells to calcitriol. Increases of RXR levels by YFP-RXR expression, drug treatments, or the combination of the two, however, restored the growth-inhibitory effects of calcitriol and 9-cis-RA and restored p21 induction by calcitriol. These studies revealed that an accelerated and aberrant RXR degradation could cause resistance to the antiproliferative effects of calcitriol and retinoids in ROS cells.


Assuntos
Calcitriol/farmacologia , Divisão Celular/efeitos dos fármacos , Osteossarcoma/patologia , Receptores do Ácido Retinoico/metabolismo , Fatores de Transcrição/metabolismo , Animais , Proteínas de Bactérias/genética , Western Blotting , Cisteína Endopeptidases/metabolismo , Resistência a Medicamentos , Expressão Gênica , Regulação da Expressão Gênica , Proteínas de Fluorescência Verde , Proteínas Luminescentes/genética , Complexos Multienzimáticos/antagonistas & inibidores , Complexos Multienzimáticos/metabolismo , Complexo de Endopeptidases do Proteassoma , Ratos , Receptores de Calcitriol/genética , Proteínas Recombinantes de Fusão , Receptores X Retinoide , Retinoides/farmacologia , Transcrição Genética , Células Tumorais Cultivadas
19.
Int J Oncol ; 20(1): 195-200, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11743664

RESUMO

Tributyrin (glyceryl tributyrate, TB) is known to induce malignant cells to differentiate followed by arrest of cell growth and death via apoptosis. We investigated the effects of TB on the distribution of cell cycle phases, differentiation as measured by alkaline phosphatase activity (ALP), and apoptosis of LS 174T colon cancer cells expressed by morphological changes, externalization of phosphatidylserine and stimulation of various caspases. TB (0.6 mM) reduced the proliferation by a 5-fold decrease of tumor cells in the S-phase and 1.3-fold increase in the G2/M-phase of cell cycle after 24 h of incubation. The ALP activity was enhanced in a dose-dependent manner up to 180-fold by 1 mM TB. Apoptosis was seen only above 0.6 mM TB (5-fold increase). Studies with caspase inhibitors revealed that TB mediated cell death was linked to up-regulation of caspases 3 and 8. Our results indicate that TB-induced differentiation promotes apoptosis in LS 174T cells and may explain the mode of action of TB finally resulting in an arrest of tumor cell growth.


Assuntos
Adenocarcinoma/patologia , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Neoplasias do Colo/patologia , Triglicerídeos/farmacologia , Adenocarcinoma/metabolismo , Fosfatase Alcalina/metabolismo , Apoptose/fisiologia , Inibidores de Caspase , Caspases/metabolismo , Divisão Celular/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Inibidores Enzimáticos/farmacologia , Humanos , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA