Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
1.
J Bone Oncol ; 13: 123-135, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30591866

RESUMO

Adjuvant bisphosphonates improve disease outcomes in postmenopausal early breast cancer (EBC) but the long-term effects are poorly described. The AZURE trial (ISRCTN79831382) was designed to determine whether adjuvant zoledronic acid (ZOL) improves disease outcomes in EBC. Previous analyses showed no effect on overall outcomes but identified benefits in postmenopausal women. Here we present the long-term risks and benefits of adjuvant ZOL with 10-years follow-up. PATIENTS AND METHODS: 3360 patients with stage II/III breast cancer were included in an academic, international, phase III, randomized, open label trial. Patients were followed up on a regular schedule until 10 years. Patients were randomized on a 1:1 basis to standard adjuvant systemic therapy +/- intravenous ZOL 4 mg every 3-4 weeks x6, and then at reduced frequency to complete 5 years treatment. The primary outcome was disease free survival (DFS). Secondary outcomes included invasive DFS (IDFS), overall survival (OS), sites of recurrence, skeletal morbidity and treatment outcomes according to primary tumor amplification of the transcription factor, MAF. Pre-planned subgroup analyses focused on interactions between menopausal status and treatment effects. RESULTS: With a median follow up of 117 months [IQR 70.4-120.4), DFS and IDFS were similar in both arms (HRDFS  = 0.94, 95%CI = 0.84-1.06, p = 0.340; HRIDFS  = 0.91, 95%CI = 0.82-1.02, p = 0.116). However, outcomes remain improved with ZOL in postmenopausal women (HRDFS  = 0.82, 95%CI = 0.67-1.00; HRIDFS  = 0.78, 95%CI = 0.64-0.94). In the 79% of tested women with a MAF FISH negative tumor, ZOL improved IDFS (HRIDFS  = 0.75, 95%CI = 0.58-0.97) and OS HROS  = 0.69, 95%CI = 0.50-0.94), irrespective of menopause. ZOL did not improve disease outcomes in MAF FISH + tumors. Bone metastases as a first DFS recurrence (BDFS) were reduced with ZOL (HRB-DFS  = 0.76, 95%CI = 0.63-0.92, p = 0.005). ZOL reduced skeletal morbidity with fewer fractures and skeletal events after disease recurrence. 30 cases of osteonecrosis of the jaw in the ZOL arm (1.8%) have occurred. CONCLUSIONS: Disease benefits with adjuvant ZOL in postmenopausal early breast cancer persist at 10 years of follow-up. The biomarker MAF identified a patient subgroup that derived benefit from ZOL irrespective of menopausal status.

2.
Int J Cancer ; 131(1): 59-69, 2012 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-21805478

RESUMO

Myxoid Liposarcomas (MLS), characterized by the expression of FUS-CHOP fusion gene are clinically very sensitive to the DNA binding antitumor agent, trabectedin. However, resistance eventually occurs, preventing disease eradication. To investigate the mechanisms of resistance, a trabectedin resistant cell line, 402-91/ET, was developed. The resistance to trabectedin was not related to the expression of MDR related proteins, uptake/efflux of trabectedin or GSH levels that were similar in parental and resistant cells. The 402-91/ET cells were hypersensitive to UV light because of a nucleotide excision repair defect: XPG complementation decreased sensitivity to UV rays, but only partially to trabectedin. 402-91/ET cells showed collateral sensitivity to temozolomide due to the lack of O(6) -methylguanine-DNA-methyltransferase (MGMT) activity, related to the hypermethylation of MGMT promoter. In 402-91 cells chromatin immunoprecipitation (ChIP) assays showed that FUS-CHOP was bound to the PTX3 and FN1 gene promoters, as previously described, and trabectedin caused FUS-CHOP detachment from DNA. Here we report that, in contrast, in 402-91/ET cells, FUS-CHOP was not bound to these promoters. Differences in the modulation of transcription of genes involved in different pathways including signal transduction, apoptosis and stress response between the two cell lines were found. Trabectedin activates the transcription of genes involved in the adipogenic-program such as c/EBPα and ß, in 402-91 but not in 402-91/ET cell lines. The collateral sensitivity of 402-91/ET to temozolomide provides the rationale to investigate the potential use of methylating agents in MLS patients resistant to trabectedin.


Assuntos
Antineoplásicos Alquilantes/farmacologia , Linhagem Celular Tumoral , Dioxóis/farmacologia , Lipossarcoma Mixoide/genética , Lipossarcoma Mixoide/metabolismo , Tetra-Hidroisoquinolinas/farmacologia , Apoptose , Proteína C-Reativa/genética , Proteína alfa Estimuladora de Ligação a CCAAT/genética , Proteína beta Intensificadora de Ligação a CCAAT/genética , Metilação de DNA , Metilases de Modificação do DNA/deficiência , Metilases de Modificação do DNA/genética , Metilases de Modificação do DNA/metabolismo , Reparo do DNA , Enzimas Reparadoras do DNA/deficiência , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Dacarbazina/análogos & derivados , Dacarbazina/farmacologia , Resistencia a Medicamentos Antineoplásicos , Fibronectinas/genética , Humanos , Lipossarcoma Mixoide/tratamento farmacológico , Lipossarcoma Mixoide/patologia , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Regiões Promotoras Genéticas , Proteína FUS de Ligação a RNA/genética , Proteína FUS de Ligação a RNA/metabolismo , Componente Amiloide P Sérico/genética , Transdução de Sinais , Temozolomida , Trabectedina , Fator de Transcrição CHOP/genética , Fator de Transcrição CHOP/metabolismo , Proteínas Supressoras de Tumor/deficiência , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Raios Ultravioleta
3.
Ann Oncol ; 23(3): 771-776, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21642514

RESUMO

BACKGROUND: To evaluate neoadjuvant trabectedin (1.5 mg/m(2) 24-h i.v. infusion every 3 weeks; three to six cycles) in patients with locally advanced myoxid liposarcoma (ML) previously untreated with chemotherapy or radiation. PATIENTS AND METHODS: Primary efficacy end point was pathological complete response (pCR) or tumoral regression rate. Objective response according to RECIST (v.1.0) was a secondary end point. RESULTS: Three of 23 assessable patients had pCR [13%; 95% confidence interval (CI), 3% to 34%]. Furthermore, very good and moderate histological responses were observed in another 2 and 10 patients, respectively. Histological decrement in the cellular and vascular tumor component and maturation of tumor cells to lipoblasts were observed in both myoxid and myoxid/round cell variants. Seven patients had partial response according to RECIST (objective response rate of 24%; 95% CI, 10% to 44%). No disease progression was reported. Neoadjuvant trabectedin was usually well tolerated, with a safety profile similar to that described in patients with soft tissue sarcoma or other tumor types. CONCLUSION: Trabectedin 1.5 mg/m(2) given as a 24-h i.v. infusion every 3 weeks is a therapeutic option in the neoadjuvant setting of ML.


Assuntos
Antineoplásicos Alquilantes/uso terapêutico , Dioxóis/uso terapêutico , Lipossarcoma Mixoide/tratamento farmacológico , Terapia Neoadjuvante , Tetra-Hidroisoquinolinas/uso terapêutico , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Trabectedina , Adulto Jovem
4.
Eur J Cancer ; 47(7): 1006-12, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21376569

RESUMO

AIM: Trabectedin sensitivity is increased in cells with functional nucleotide excision DNA repair, whereas efficient homologous recombination repair leads to resistance. On this basis, a retrospective study of mRNA expression of BRCA1 (breast cancer susceptibility 1 gene), XPG (Xeroderma pigmentosum group G gene) and ERCC1 (excision-repair cross complementing group 1 gene) in tumour samples from sarcoma patients treated with trabectedin was conducted, to correlate DNA repair profiles with patient outcome. MATERIALS AND METHODS: Quantification of expression in paraffin embedded tumour samples from 245 patients with advanced sarcomas was performed by qRT-PCR (quantitative real-time polymerase chain reaction). Median values were used as cut-off to define low/high mRNA expression. RESULTS: Low BRCA1 mRNA expression in tumour samples correlated with statistically significant better response to trabectedin. In contrast to other DNA interacting agents, high expression of XPG was significantly correlated with increased response to the drug and high ERCC1 or XPD (Xeroderma pigmentosum group D gene) expression did not have a detrimental impact. A composite signature including low BRCA1 and high ERCC1 and/or XPG identifies a highly sensitive population of sarcomas with significantly improved treatment outcome. DISCUSSION: This retrospective study indicates that the DNA repair profile predicts improved outcomes in advanced sarcoma patients when treated with trabectedin. This clinical utility of this signature should be evaluated in prospective enriching studies in sarcoma and other malignancies for patients sensitive to trabectedin.


Assuntos
Antineoplásicos Alquilantes/uso terapêutico , Reparo do DNA , Dioxóis/uso terapêutico , Sarcoma/tratamento farmacológico , Sarcoma/genética , Tetra-Hidroisoquinolinas/uso terapêutico , Proteína BRCA1/genética , Proteínas de Ligação a DNA/genética , Endonucleases/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Proteínas Nucleares/genética , RNA Mensageiro/metabolismo , Recombinação Genética , Estudos Retrospectivos , Trabectedina , Fatores de Transcrição/genética , Resultado do Tratamento
5.
Ann Oncol ; 20(8): 1439-44, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19465423

RESUMO

BACKGROUND: Trabectedin has been approved in Europe as second-line therapy for advanced soft tissue sarcomas. A previous analysis showed that myxoid liposarcomas (MLS) are particularly sensitive to the drug. We report on the long-term efficacy of trabectedin in a subgroup of that series. METHODS: Since September 2002, 32 advanced pretreated MLS patients received trabectedin at our center. Data were reviewed focusing on their long-term outcome. RESULTS: Trabectedin was given as a 24-h continuous infusion every 21 days. A total of 376 and a median of 12 courses per patient (range 2-26; interquartiles range (IQR) 8-15) were delivered. Response rate per RECIST was 50% [95% confidence interval (CI) 32% to 68%], median progression-free survival (PFS) was 17 months (95% CI 13.5-30.1) and median overall survival is still not reached. In 10 patients, therapy was stopped in the absence of any evident disease, mostly after complete surgery of residual lesions. In these 10 patients, at a median follow-up of 25 months, PFS was 28.1 months (95% CI 25.6-36.4) from treatment start. DISCUSSION: These data indicate that the high response rate of MLS to trabectedin translates into prolonged PFS. Surgery of residual metastatic disease is already used quite extensively in metastatic MLS. Trabectedin may give further significance to this kind of surgery.


Assuntos
Antineoplásicos Alquilantes/administração & dosagem , Dioxóis/administração & dosagem , Lipossarcoma Mixoide/tratamento farmacológico , Neoplasias de Tecidos Moles/tratamento farmacológico , Tetra-Hidroisoquinolinas/administração & dosagem , Adulto , Idoso , Antineoplásicos Alquilantes/efeitos adversos , Dioxóis/efeitos adversos , Intervalo Livre de Doença , Relação Dose-Resposta a Droga , Esquema de Medicação , Feminino , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Tetra-Hidroisoquinolinas/efeitos adversos , Coxa da Perna , Trabectedina
6.
J Clin Microbiol ; 39(5): 1813-8, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11325996

RESUMO

Genetic alterations in the rpoB gene were characterized in 50 rifampin-resistant (Rif(r)) clinical isolates of Mycobacterium tuberculosis complex from Spain. A rapid PCR-enzyme-linked immunosorbent assay (ELISA) technique for the identification of rpoB mutations was evaluated with isolates of the M. tuberculosis complex and clinical specimens from tuberculosis patients that were positive for acid-fast bacilli (AFB). Sequence analysis demonstrated 11 different rpoB mutations among the Rif(r) isolates in the study. The most frequent mutations were those associated with codon 531 (24 of 50; 48%) and codon 526 (11 of 50; 22%). Although the PCR-ELISA does not permit characterization of the specific Rif(r) allele within each strain, 10 of the 11 Rif(r) genotypes were correctly identified by this method. We used the PCR-ELISA to predict the rifampin susceptibility of M. tuberculosis complex organisms from 30 AFB-positive sputum specimens. For 28 samples, of which 9 contained Rif(r) organisms and 19 contained susceptible strains, results were concordant with those based on culture-based drug susceptibility testing and sequencing. Results from the remaining two samples could not be interpreted because of low bacillary load (microscopy score of 1+ for 1 to 9 microorganisms/100 fields). Our results suggest that the PCR-ELISA is an easy technique to implement and could be used as a rapid procedure for detecting rifampin resistance to complement conventional culture-based methods.


Assuntos
RNA Polimerases Dirigidas por DNA/genética , Ensaio de Imunoadsorção Enzimática , Mutação , Mycobacterium tuberculosis/efeitos dos fármacos , Reação em Cadeia da Polimerase/métodos , Rifampina/farmacologia , Sequência de Aminoácidos , Antibióticos Antituberculose/farmacologia , Sequência de Bases , Meios de Cultura , RNA Polimerases Dirigidas por DNA/química , Resistência Microbiana a Medicamentos/genética , Humanos , Dados de Sequência Molecular , Mycobacterium tuberculosis/genética , Sensibilidade e Especificidade , Análise de Sequência de DNA , Espanha , Tuberculose/microbiologia
7.
Int J Tuberc Lung Dis ; 4(8): 765-70, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10949329

RESUMO

SETTING: Cases of rifampin-resistant Mycobacterium tuberculosis from the prison population in Madrid and from the general population in Spain. OBJECTIVE: To identify the rpoB mutations associated with resistance to rifampin and to investigate rpoB genotyping as an epidemiological marker in rifampin-resistant M. tuberculosis. DESIGN: Twenty-nine rifampin-resistant clinical isolates of M. tuberculosis, 15 obtained from the prison population in Madrid and 14 from the general population in Spain, were characterized by sequence analysis of the 81-bp core region of the rpoB gene and IS6110 DNA fingerprinting. RESULTS: All the isolates had mutations in rpoB, with those in codon 531 accounting for 41% of the total. Twenty-three (79%) isolates were highly resistant to rifampin (minimum inhibitory concentration > or = 64 mg/L). Nineteen different IS6110 fingerprints were observed: one was shared by seven isolates, one by three, two by two, and 15 were unique. Two IS6110 clusters could be divided into subclusters on the basis of rpoB analysis. Epidemiologic links were identified among patients whose isolates had identical IS6110 patterns and rpoB genotypes, but not between those with identical IS6110 patterns and different rpoB genotypes. CONCLUSION: Characterization of rpoB mutations can provide information about susceptibility to rifampin and be a useful epidemiological tool for discrimination of rifampin-resistant strains of M. tuberculosis with identical IS6110 fingerprints.


Assuntos
Antibióticos Antituberculose/uso terapêutico , Mutação , Mycobacterium tuberculosis/genética , Rifampina/uso terapêutico , Tuberculose/microbiologia , Antibióticos Antituberculose/farmacologia , Biomarcadores , Impressões Digitais de DNA , Resistência Microbiana a Medicamentos , Genótipo , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/isolamento & purificação , Prisioneiros , Rifampina/farmacologia , Análise de Sequência de DNA , Espanha/epidemiologia , Tuberculose/tratamento farmacológico , Tuberculose/epidemiologia
8.
J Periodontal Res ; 33(1): 59-64, 1998 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9524322

RESUMO

The identification of specific periodontal pathogens by conventional methods, mainly anaerobic cultivation, is difficult, time consuming and even sometimes unreliable. Therefore, a multiplex PCR method for simultaneous detection of Actinobacillus actinomycetemcomitans (A.a.), Porphyromona gingivalis (P.g.) and Prevotella intermedia (P.i.) was developed for rapid and easy identification of these specific bacterial pathogens in subgingival plaque samples. In this paper, there is a detailed description of the oligonucleotide primer selection, DNA extraction and PCR conditions and the sequencing of the amplified products. The locus chosen to be amplified is a highly variable region in the 16S ribosomal DNA. For the development of this technique ATCC cultures and pure cultures from subgingival plaque samples taken from periodontitis patients were used. As an internal positive control a recombinant plasmid was developed. This simple DNA extraction procedure and the DNA amplification and visualization of the amplified product permits the detection of the bacteria in a working day. Thus, this multiplex PCR method is a rapid and effective detection method for specific periodontal pathogens.


Assuntos
Aggregatibacter actinomycetemcomitans/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Porphyromonas gingivalis/isolamento & purificação , Prevotella intermedia/isolamento & purificação , Aggregatibacter actinomycetemcomitans/genética , Sequência de Bases , Mapeamento Cromossômico , Primers do DNA , DNA Bacteriano/análise , DNA Recombinante/genética , Placa Dentária/microbiologia , Amplificação de Genes , Genoma Bacteriano , Humanos , Periodontite/microbiologia , Plasmídeos/genética , Porphyromonas gingivalis/genética , Prevotella intermedia/genética , RNA Ribossômico 16S/análise , Sensibilidade e Especificidade
9.
J Clin Microbiol ; 33(1): 33-6, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7699061

RESUMO

Mycobacterium bovis is a slowly growing microorganism, and confirmation of the diagnosis by conventional culture is a lengthy process. A simple, rapid method for the extraction of DNA from bovine tissue samples was developed and used in a PCR designed for the diagnosis of tuberculosis. Tissues from 81 cattle from tuberculosis-infected herds (group 1) and 19 cattle from tuberculosis-free herds (group 2) were tested in this PCR, and the results were compared with those of conventional culture. The PCR assay detected 71.4% of the culture-positive animals from group 1. Tissue from all animals in group 2 were negative in the PCR assay and by culture. The described method could be used as a rapid screening technique which would be complementary to culture of tissue specimens for the routine diagnosis of bovine tuberculosis. The PCR technique is much faster than culture and reduces the time for diagnosis from several months to 2 days. It also provides for the detection of M. bovis when rapidly growing Mycobacterium spp. are present in the sample and may be able to detect the presence of M. bovis in samples even when organisms have become nonviable.


Assuntos
Reação em Cadeia da Polimerase/métodos , Tuberculose Bovina/diagnóstico , Animais , Sequência de Bases , Southern Blotting , Bovinos , DNA Bacteriano/isolamento & purificação , Reações Falso-Negativas , Dados de Sequência Molecular , Fatores de Tempo
10.
J Bacteriol ; 175(10): 3192-4, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8491733

RESUMO

The MAK3 gene of Saccharomyces cerevisiae encodes an N-acetyltransferase whose acetylation of the N terminus of the L-A double-stranded RNA virus major coat protein (gag) is necessary for viral assembly. We show that the first 4 amino acids of the L-A gag protein sequence, MLRF, are a portable signal for N-terminal acetylation by MAK3. Amino acids 2, 3, and 4 are each important for acetylation by the MAK3 enzyme. In yeast cells, only three mitochondrial proteins are known to have the MAK3 acetylation signal, suggesting an explanation for the slow growth of mak3 mutants on nonfermentable carbon sources.


Assuntos
Acetiltransferases/genética , Arilamina N-Acetiltransferase , Proteínas Fúngicas/genética , Produtos do Gene gag/metabolismo , Vírus de RNA/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Acetilação , Sequência de Aminoácidos , Sequência de Bases , Dados de Sequência Molecular , Processamento de Proteína Pós-Traducional , RNA de Cadeia Dupla , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/enzimologia , beta-Galactosidase/genética , beta-Galactosidase/metabolismo
11.
J Biol Chem ; 267(28): 20277-81, 1992 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-1400344

RESUMO

The MAK3 gene is necessary for propagation of the L-A double-stranded RNA virus of Saccharomyces cerevisiae. MAK3 encodes a protein with substantial homology to the Escherichia coli rimI N-acetyltransferase that acetylates the NH2 terminus of ribosomal protein S18, and shares consensus sequences with a group of N-acetyltransferases. The NH2 terminus of the viral major coat protein encoded by L-A is normally blocked, but we find that it is unblocked in a mak3-1 mutant. L-A virus-encoded proteins produced from a cDNA clone of L-A can encapsidate the L-A (+)-strands in a wild-type host, but not in a mak3-1 mutant strain. The amount of major coat protein found in the particle fraction is reduced greater than 100-fold, and the amount in the total cell extract is reduced 5-10-fold. A modified beta-galactosidase, having as its NH2-terminal the NH2-terminal 13 residues of the L-A-encoded major coat protein, is blocked in a wild-type host, but not in a mak3-1 host. We propose that MAK3 encodes an N-acetyltransferase whose modification of the L-A major coat protein NH2 terminus is essential for viral assembly, and that unassembled coat protein is unstable.


Assuntos
Arilamina N-Acetiltransferase/genética , Capsídeo/metabolismo , Proteínas Fúngicas/genética , Produtos do Gene gag/metabolismo , Vírus de RNA/fisiologia , Proteínas de Saccharomyces cerevisiae , Acetilação , Sequência de Aminoácidos , Arilamina N-Acetiltransferase/metabolismo , Sequência de Bases , Northern Blotting , Western Blotting , DNA Viral , Proteínas Fúngicas/metabolismo , Plasmídeos , RNA Viral/metabolismo , Replicação Viral
12.
J Biol Chem ; 267(28): 20270-6, 1992 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-1339437

RESUMO

The MAK3 gene of Saccharomyces cerevisiae is necessary for the propagation of the L-A double-stranded RNA virus and its satellites, such as M1 that encodes a killer toxin. We cloned the MAK3 gene based on its genetic map position using physically mapped lambda-clones covering nearly all of the yeast genome. The minimal sequence necessary to complement the mak3-1 mutation contained 3 open reading frames (ORFs). Only one (ORF3) was necessary to complement mak3-1. A deletion insertion mutant of ORF3 grew slowly on nonfermentable carbon sources, an effect not due simply to its loss of L-A. Although ORF3 alone is sufficient for MAK3 activity when expressed from an expression vector, in its native context an additional 669 base pairs 3' to the ORF and complementary to the gene for a non-histone protein are necessary for expression, but not for normal steady state transcript levels. This suggests a post-transcriptional control of MAK3 expression by the 3' region. The MAK3 protein has substantial homology with several N-acetyltransferases with consensus patterns h..h.h. . . Y..[HK]GI[AG][KR].Lh. . .h and h.h[DE]. . . .N..A. . .Y . . .GF. . . .. . . .Y . . [DE]G, (h = hydrophobic). Mutation of any of the underlined conserved residues (94GI----AA, 123N----A, 130Y----A, 134GF----SL, 144Y----A, and 149G----A) inactivated the gene, supporting the hypothesis that MAK3 encodes an N-acetyltransferase.


Assuntos
Arilamina N-Acetiltransferase/genética , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Mutagênese , Vírus de RNA/fisiologia , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Sequência de Aminoácidos , Arilamina N-Acetiltransferase/metabolismo , Sequência de Bases , Mapeamento Cromossômico , Passeio de Cromossomo , Clonagem Molecular , DNA Fúngico , Proteínas Fúngicas/metabolismo , Dados de Sequência Molecular , Fases de Leitura Aberta , Plasmídeos , RNA de Cadeia Dupla , RNA Mensageiro/metabolismo , Mapeamento por Restrição , Saccharomyces cerevisiae/enzimologia , Homologia de Sequência de Aminoácidos , Replicação Viral
13.
Biochemistry ; 30(19): 4753-62, 1991 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-2029517

RESUMO

The effect of the initial pH and the concentrations of thrombin, fibrinogen, and Ca2+ upon the rate of pH change associated with clotting of bovine fibrinogen by human thrombin was investigated at pH 6.80, 7.80, and 8.80, 0.3 ionic strength, 25 degrees C, and 19.5 mg/mL final fibrinogen concentration. At pH 6.80 and 7.80, the reaction was first order, with rate constant k1. At pH 8.80, a first-order reaction of the release of H+ (k1) was followed by a partial rebinding of these in a reaction consecutive to the first one (k2). At each of the above pH values, k1 was proportional to thrombin concentration in the 0.05-3.0 min-1 range investigated. The k1 constants were 0.111 +/- 0.001, 0.250 +/- 0.005, and 0.190 +/- 0.002 min-1 (NIH thrombin units)-1 mL-1 at pH 6.80, 7.80, and 8.80, respectively. Plots of log rate vs log thrombin concentration of these data were linear with slopes close to 1 at all three pH values. The rate of the second reaction (k2) was independent of both the thrombin and the initial fibrinogen concentration. The pH dependence of k1 exhibited a bell-shaped curve that could be resolved into the effect of one group with a pK of 7.27 that increased the rate and another with a pK of 9.22 that decreased the rate. With constant thrombin concentration but varying fibrinogen concentration, plots of 1/k1 vs [fibrinogen] were linear, but the lines did not pass through the origin. From the slope and intercept, kcat and KM of the Michaelis-Menten equation could be calculated. The same parameters were obtained also from initial velocity vs [fibrinogen] plots. Values of kcat were consistent and accurate; those of KM were more scattered. KM was (22.4-34.2) X 10(-6) M at pH 6.80 and approximately 7 X 10(-6) M in the pH 7.26-8.80 range. The latter value, pertaining to the release of H+ ions, is in agreement with values in the literature for KM of the release of fibrinopeptide A by thrombin in the 7.4-8.0 pH range. The value of kcat s-1 (unit of thrombin)-1 mL-1 increases from 1.2 X 10(-10) s-1 unit of thrombin-1 mL-1 at pH 6.80 to 2.46 X 10(-10) at pH 7.80 and then decreases to 2.01 X 10(-10) 10(-1) (units of thrombin)-1 mL-1 at pH 8.80. The kcat values are significantly lower than those in the literature for the release of fibrinopeptide A.(ABSTRACT TRUNCATED AT 400 WORDS)


Assuntos
Fibrinogênio/metabolismo , Fibrinopeptídeo A/metabolismo , Fibrinopeptídeo B/metabolismo , Trombina/metabolismo , Animais , Bovinos , Fibrinogênio/fisiologia , Humanos , Concentração de Íons de Hidrogênio , Cinética , Concentração Osmolar , Polímeros
14.
Thromb Res ; 55(2): 221-32, 1989 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-2781526

RESUMO

A method for the fractionation of plasmic digests of both fibrinogen and fibrin was developed by taking advantage of the different chromatographic behaviour of fibrinogen and its fragments on immobilized concanavalin A and Lens culinaris agglutinin. Columns with different lectin concentration but with the same total lectin content were tested. Fragment E was retained on all the concanavalin A-Sepharose preparations while fragment D was mostly eluted in the unbound fraction. However, the binding of fragment DD depended on the lectin concentration of the gel. Thus, the percentage of fragment DD specifically bound to concanavalin A-Sepharose increased from 5-10% to 67% as the lectin density of the gel increased from 0.9 to 8.7 mg/ml gel. On the other hand, Lens culinaris agglutinin-Sepharose retained fibrinogen and high molecular weight fragments depending on the lectin concentration of the gel while neither fragment E nor fragment D were bound to any of the columns.


Assuntos
Produtos de Degradação da Fibrina e do Fibrinogênio/isolamento & purificação , Lectinas de Plantas , Configuração de Carboidratos , Fracionamento Químico/métodos , Cromatografia de Afinidade , Concanavalina A , Humanos , Lectinas
15.
Anal Biochem ; 174(1): 128-36, 1988 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3218727

RESUMO

Fibrinogen binds specifically to Lens culinaris agglutinin coupled to CNBr-activated Sepharose. However, a fraction of the retained fibrinogen remains tightly bound to the gel and is eluted only by electrophoretic desorption. The irreversible binding of fibrinogen results from the interaction of fibrinogen specifically bound to the immobilized lectin with some reactive groups still present on the Sepharose matrix. Therefore, the active groups present on lectin-Sepharose after different treatments and their influence on the irreversible binding of fibrinogen have been studied. After the coupling step some cyanate esters remain on the gel, but they are neutralized under all the conditions studied. In addition, imidocarbonates formed under the basic conditions used to activate Sepharose, and carbonates resulting from acid treatment of the gel, are also present. Carbonates seem to be the main active groups involved in the irreversible binding of fibrinogen to lectin-Sepharose. Imidocarbonates also contribute to the nonspecific binding, although to a lesser extent than carbonates. Treatment of CNBr-activated Sepharose with 0.1 M HCl prior to the coupling step and neutralization, after coupling, with 0.1 M ethanolamine, pH 9.5, for 24 h at room temperature reduce the nonspecific binding to less than 9% of the fibrinogen fraction retained by the column. This percentage is appreciably smaller than that obtained by neutralization for 2 h at room temperature with either 0.1 M Tris-HCl, pH 8.0 (congruent to 66%), or 1 M ethanolamine, pH 9.0 (congruent to 23%).


Assuntos
Cromatografia de Afinidade/métodos , Fibrinogênio/isolamento & purificação , Lectinas de Plantas , Adsorção , Sítios de Ligação , Brometo de Cianogênio , Lectinas , Sefarose
16.
Clin Chem ; 27(11): 1915-7, 1981 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-7028318

RESUMO

We assessed the potential usefulness of 16 alpha-[125I]-beta-estradiol in estradiol receptor assays as compared with a long-used [3H]-beta-estradiol dextran-coated charcoal method, measuring 472 consecutive human breast-cancer cytosols by both procedures. Six different preparations of 16 alpha-[125I]-beta-estradiol were used. Nonspecific binding in five batches was similar and comparable to [3H]-beta-estradiol. Although the sixth batch had increased nonspecific binding, this did not affect results. Dissociation constants were virtually identical (r = 0.94). Results were concordant for 98.5% of cytosols: 161 were negative and 304 positive by both methods and seven were positive by one method, negative by the other. Four were positive with the 125I procedure and undetectable with [3H]-beta-estradiol. Three were measurable by both methods, but were above the cut-off value in one and below it in the other. We find 16 alpha-[125I]-beta-estradiol to be an adequate substitute for [3H]-beta-estradiol in estradiol receptor assays.


Assuntos
Neoplasias da Mama/metabolismo , Estradiol/metabolismo , Receptores de Estrogênio/metabolismo , Citosol/metabolismo , Feminino , Humanos , Radioisótopos do Iodo , Cinética , Técnica de Diluição de Radioisótopos , Receptores de Estradiol , Trítio
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...