RESUMO
BACKGROUND AND PURPOSE: Recent advances in molecular techniques have characterized distinct subtypes of diffuse intrinsic pontine gliomas. Our aim was the identification of MR imaging correlates of these subtypes. MATERIALS AND METHODS: Initial MRIs from subjects with diffuse intrinsic pontine gliomas recruited for a prospective clinical trial before treatment were analyzed. Retrospective imaging analyses included FLAIR/T2 tumor volume, tumor volume enhancing, the presence of cyst and/or necrosis, median, mean, mode, skewness, kurtosis of ADC tumor volume based on FLAIR, and enhancement at baseline. Molecular subgroups based on EGFR and MGMT mutations were established. Histone mutations were also determined (H3F3A, HIST1H3B, HIST1H3C). Univariate Cox proportional hazards regression was used to test the association of imaging predictors with overall and progression-free survival. Wilcoxon rank sum, Kruskal-Wallis, and Fisher exact tests were used to compare imaging measures among groups. RESULTS: Fifty patients had biopsy and MR imaging. The median age at trial registration was 6 years (range, 3.3-17.5 years); 52% were female. On the basis of immunohistochemical results, 48 patients were assigned to 1 of 4 subgroups: 28 in MGMT-/epidermal growth factor receptor (EGFR)-, 14 in MGMT-/EGFR+, 3 in MGMT+/EGFR-, and 3 in MGMT+/EGFR+. Twenty-three patients had histone mutations in H3F3A, 8 in HIST1H3B, and 3 in HIST1H3C. Enhancing tumor volume was near-significantly different across molecular subgroups (P = .04), after accounting for the false discovery rate. Tumor volume enhancing, median, mode, skewness, and kurtosis ADC T2-FLAIR/T2 were significantly different (P ≤ .048) between patients with H3F3A and HIST1H3B/C mutations. CONCLUSIONS: MR imaging features including enhancement and ADC histogram parameters are correlated with molecular subgroups and mutations in children with diffuse intrinsic pontine gliomas.
Assuntos
Neoplasias do Tronco Encefálico/diagnóstico por imagem , Neoplasias do Tronco Encefálico/genética , Glioma Pontino Intrínseco Difuso/diagnóstico por imagem , Glioma Pontino Intrínseco Difuso/genética , Neuroimagem/métodos , Adolescente , Criança , Pré-Escolar , Análise Mutacional de DNA/métodos , Receptores ErbB/genética , Feminino , Histonas/genética , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Mutação , Estudos Prospectivos , Estudos RetrospectivosRESUMO
PURPOSE: Children with Hutchinson-Gilford progeria syndrome (HGPS), a rare premature aging disease, exhibit extraskeletal calcifications detected by radiographic analysis and on physical examination. The aim of this study was to describe the natural history and pathophysiology of these abnormal calcifications in HGPS, and to determine whether medications and/or supplements tested in clinical trials alter their development. METHODS: Children from two successive clinical trials administering 1) lonafarnib (nâ¯=â¯26) and 2) lonafarnibâ¯+â¯pravastatinâ¯+â¯zoledronic acid (nâ¯=â¯37) were studied at baseline (pre-therapy), one year on therapy, and at end-of-therapy (3.3-4.3â¯years after the baseline visit). Calcium supplementation (oral calcium carbonate) was administered during the first year of the second trial and was subsequently discontinued. Information on calcifications was obtained from physical examinations, radiographs, and serum and urinary biochemical measures. The mineral content of two skin-derived calcifications was determined by x-ray diffraction. RESULTS: Extraskeletal calcifications were detected radiographically in 12/39 (31%) patients at baseline. The odds of exhibiting calcifications increased with age (pâ¯=â¯0.045). The odds were unaffected by receipt of lonafarnib, pravastatin, and zoledronate therapies. However, administration of calcium carbonate supplementation, in conjunction with all three therapeutic agents, significantly increased the odds of developing calcifications (pâ¯=â¯0.009), with the odds plateauing after the supplement's discontinuation. Composition analysis of calcinosis cutis showed hydroxyapatite similar to bone. Although serum calcium, phosphorus, and parathyroid hormone (PTH) were within normal limits at baseline and on-therapy, PTH increased significantly after lonafarnib initiation (pâ¯<â¯0.001). Both the urinary calcium/creatinine ratio and tubular reabsorption of phosphate (TRP) were elevated at baseline in 22/39 (56%) and 31/37 (84%) evaluable patients, respectively, with no significant changes while on-therapy. The mean calciumâ¯×â¯phosphorus product (Caâ¯×â¯Pi) was within normal limits, but plasma magnesium decreased over both clinical trials. Fibroblast growth factor 23 (FGF23) was lower compared to age-matched controls (pâ¯=â¯0.03). CONCLUSIONS: Extraskeletal calcifications increased with age in children with HGPS and were composed of hydroxyapatite. The urinary calcium/creatinine ratio and TRP were elevated for age while FGF23 was decreased. Magnesium decreased and PTH increased after lonafarnib therapy which may alter the ability to mobilize calcium. These findings demonstrate that children with HGPS with normal renal function and an unremarkable Caâ¯×â¯Pi develop extraskeletal calcifications by an unidentified mechanism that may involve decreased plasma magnesium and FGF23. Calcium carbonate accelerated their development and is, therefore, not recommended for routine supplementation in these children.
Assuntos
Calcinose/patologia , Progéria/patologia , Calcinose/sangue , Calcinose/diagnóstico por imagem , Calcinose/tratamento farmacológico , Cálcio/sangue , Criança , Pré-Escolar , Creatinina/sangue , Feminino , Fator de Crescimento de Fibroblastos 23 , Humanos , Técnicas In Vitro , Lamina Tipo A/metabolismo , Masculino , Hormônio Paratireóideo/sangue , Hormônio Paratireóideo/metabolismo , Piperidinas/uso terapêutico , Pravastatina/uso terapêutico , Progéria/sangue , Progéria/diagnóstico por imagem , Progéria/tratamento farmacológico , Piridinas/uso terapêutico , Ácido Zoledrônico/uso terapêuticoRESUMO
BACKGROUND AND PURPOSE: Accurate tumor grading is essential for treatment planning of pediatric brain tumors. We hypothesized that multiparametric analyses of a combination of permeability metrics and ADC histogram metrics would differentiate high- and low-grade tumors with high accuracy. MATERIALS AND METHODS: DTI and dynamic contrast-enhanced MR imaging using T1-mapping with flip angles of 2°, 5°, 10°, and 15°, followed by a 0.1-mmol/kg body weight gadolinium-based bolus was performed on all patients in addition to standard MR imaging. Permeability data were processed and transfer constant from the blood plasma into the extracellular extravascular space, rate constant from the extracellular extravascular space back into blood plasma, extravascular extracellular volume fraction, and fractional blood plasma volume were calculated from 3D tumor volumes. Apparent diffusion coefficient histogram metrics were calculated for 3 separate tumor volumes derived from T2-FLAIR sequences, T1 contrast-enhanced sequences, and permeability maps, respectively. RESULTS: Results from 41 patients (0.3-16.76 years of age; mean, 6.22 years) with newly diagnosed contrast-enhancing brain tumors (16 low-grade; 25 high-grade) were included in the institutional review board-approved retrospective analysis. Wilcoxon tests showed a higher transfer constant from blood plasma into extracellular extravascular space and rate constant from extracellular extravascular space back into blood plasma, and lower extracellular extravascular volume fraction (P < .001) in high-grade tumors. The mean ADCs of FLAIR and enhancing tumor volumes were significantly lower in high-grade tumors (P < .001). ROC analysis showed that a combination of extravascular volume fraction and mean ADC of FLAIR volume differentiated high- and low-grade tumors with high accuracy (area under receiver operating characteristic curve = 0.918). CONCLUSIONS: ADC histogram metrics combined with permeability metrics differentiate low- and high-grade pediatric brain tumors with high accuracy.
Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/patologia , Imageamento por Ressonância Magnética/métodos , Gradação de Tumores/métodos , Adolescente , Neoplasias Encefálicas/classificação , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Permeabilidade , Curva ROC , Estudos RetrospectivosRESUMO
Administration of chemotherapy is often limited by myelosuppression. Expression of drug-resistance genes in hematopoietic cells has been proposed as a means to decrease the toxicity of cytotoxic agents. In this pilot study, we utilized a retroviral vector expressing methylguanine DNA methyltransferase (MGMT) to transduce hematopoietic progenitors, which were subsequently used in the setting of alkylator therapy (procarbazine, CCNU, vincristine (PCV)) for poor prognosis brain tumors. Granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood progenitor cells were collected by apheresis and enriched for CD34+ expression. Nine subjects were infused with CD34+-enriched cells treated in a transduction procedure involving a 4-day exposure to cytokines with vector exposure on days 3 and 4. No major adverse event was related to the gene therapy procedure. Importantly, the engraftment kinetics of the treated product was similar to unmanipulated peripheral blood stem cells, suggesting that the ex vivo manipulation did not significantly reduce engrafting progenitor cell function. Gene-transduced cells were detected in all subjects. Although the level and duration was limited, patients receiving cells transduced using fibronectin 'preloaded' with virus supernatant appeared to show improved in vivo marking frequency. These findings demonstrate the feasibility and safety of utilizing MGMT-transduced CD34+ peripheral blood progenitor cells in the setting of chemotherapy.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/terapia , Terapia Genética/métodos , Vetores Genéticos/genética , Lomustina/uso terapêutico , O(6)-Metilguanina-DNA Metiltransferase/genética , Procarbazina/uso terapêutico , Vincristina/uso terapêutico , Adolescente , Adulto , Antígenos CD34/metabolismo , Antineoplásicos/uso terapêutico , Neoplasias Encefálicas/genética , Ensaio de Unidades Formadoras de Colônias , Primers do DNA , Feminino , Fibronectinas/metabolismo , Vetores Genéticos/metabolismo , Fator Estimulador de Colônias de Granulócitos/metabolismo , Humanos , Lomustina/administração & dosagem , Masculino , Pessoa de Meia-Idade , O(6)-Metilguanina-DNA Metiltransferase/metabolismo , Transplante de Células-Tronco de Sangue Periférico/métodos , Projetos Piloto , Reação em Cadeia da Polimerase , Procarbazina/administração & dosagem , Retroviridae/genética , Transdução Genética/métodos , Vincristina/administração & dosagemRESUMO
The pattern of reactivity of 10 monoclonal antibodies (MCA) developed against human lymphoid leukemia cells and tested with human T-cells, B-cells, as well T-lymphoma and B-lymphoma cell lines suggested that six of them detect la-like determinants, three detect HLA-like determinants, and the remaining one detects a non-Ia B-cell antigen. With the use of three binding assays, the six MCA that appeared to detect Ia-like determinants reacted strongly with the human colorectal cancer cell (CCC) line LoVo, and none of the three MCA that reacted with HLA-like determinants reacted with this cell line. Immunoprecipitation and polyacrylamide gel electrophoresis analysis confirmed the apparent specificities of the MCA for Ia-like and HLA molecules, demonstrated the presence of Ia-like molecules in LoVo, and failed to detect HLA in these cells. The cellular enzyme-linked immunosorbent assay was used for the testing of our anti-Ia and anti-HLA MCA with 15 other CCC lines. Marked heterogeneity was found in the expression of different Ia-like and HLA determinants defined by different or overlapping subsets of MCA, which suggested that these determinants might be present on different molecules or that different conformations of the same molecules exist in various CCC lines. Analysis of the surface phenotype of subclones of LoVo cells revealed the presence of stable variant cell subpopulations, which lost reactivity with four out of six of the anti-Ia-like MCA but retained at least one Ia-like molecule recognized by two of our MCA. All of the subclones maintained the HLA-negative phenotype. The possible immunologic and diagnostic consequences of the presence or absence of Ia-like or HLA markers on nonlymphoid tumor cells are discussed.
Assuntos
Anticorpos Monoclonais/imunologia , Neoplasias do Colo/imunologia , Antígenos HLA/análise , Antígenos de Histocompatibilidade Classe II/análise , Neoplasias Retais/imunologia , Linhagem Celular , Ensaio de Imunoadsorção Enzimática , Epitopos , Imunofluorescência , Antígenos HLA/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Humanos , RadioimunoensaioRESUMO
There are at least three distinct MAP kinase signaling modules in mammalian cells, distinguished by the family of kinases (Erk, SAPK/JNK, or p38) that is ultimately activated. Many input signals activate multiple MAP kinase cascades, and the mechanisms that control the specificity of signal output are not well understood. We show that SEK1/MKK4, a MAP kinase kinase proposed to activate SAPK/JNK, is a very potent inhibitor of p54 SAPK beta/JNK3 both in vitro and in vivo if present at equimolar or higher ratios. In contrast SEK can activate SAPK when present in substoichiometric amounts, but this activation is slow, consistent with the rate-limiting step in activation being the dissociation of an inactive SEK:SAPK complex. The N-terminal unique region of SEK is both necessary and partially sufficient for inhibition of SAPK, and is also necessary for activation of SAPK by SEK in vitro. We have also used the p38 MAP kinase and its activator MKK6 to examine the regulatory relationships among different kinases involved in stress responses. We show using purified kinases that inhibitory activity is specific for the combination of SEK and SAPK: SEK can activate but not inhibit p38, and MKK6 can activate but not inhibit SAPK beta and p38. These results reveal a potential mechanism for regulating stress-activated kinases, adding to a growing body of evidence suggesting that MAP kinases are controlled by relatively stable interactions with their activators.
Assuntos
Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Animais , Linhagem Celular , Ativação Enzimática , Humanos , Cinética , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Dados de Sequência Molecular , Ratos , XenopusRESUMO
The degree of erythroid chimaerism from chickens made chimaeric following stem cell infusion as embryos has been determined using a sensitive and simple procedure with monoclonal antibodies (MAbs) specific for erythroid differentiation (B-G) antigens. Highly labelled fluorescent latex beads coupled to specific MAbs have allowed for the detection of very low frequency chimaeric cell subpopulations. A direct correlation between the chimaerism of the bone marrow cells, from which mature RBCs had been eliminated, and the percentage RBC chimaerism in the blood was found. This comprises additional evidence that the B-G bearing bone marrow cells are precursors for mature RBCs.
Assuntos
Antígenos de Grupos Sanguíneos/genética , Células da Medula Óssea , Quimera , Células-Tronco Hematopoéticas/imunologia , Técnicas Imunológicas , Animais , Anticorpos Monoclonais/imunologia , Antígenos de Grupos Sanguíneos/imunologia , Embrião de Galinha , Galinhas , Eritropoese , Genótipo , Células-Tronco Hematopoéticas/citologia , MicroesferasRESUMO
We used microscopy, immunohistochemistry, and cell culture to identify the mechanism of restenosis in 4 infants with isolated pulmonary vein stenosis. Recurrent obstruction appears to be due to myofibroblastic proliferation in this fatal disease.
Assuntos
Veias Pulmonares/anormalidades , Veias Pulmonares/patologia , Constrição Patológica/patologia , Constrição Patológica/terapia , Evolução Fatal , Humanos , Lactente , Recém-NascidoRESUMO
A rare vascular portohepatic anomaly was identified in a Down syndrome patient with a 47,XY,-2,+der(2),+der(21)t(2;21)(p13;q22.1) mat chromosomal complement. This vascular defect involves a direct communication between the right portal vein and the inferior vena cava (IVC). We discuss the possibility that this vascular defect is a rare manifestation in Down syndrome. Alternatively, the existence of these 2 rare events in the same patient raises the possibility that they are causally related.
Assuntos
Cromossomos Humanos Par 21 , Cromossomos Humanos Par 2 , Síndrome de Down/genética , Fístula/genética , Veia Porta/anormalidades , Translocação Genética , Veia Cava Inferior/anormalidades , Canal Arterial/anormalidades , Ecocardiografia , Humanos , Recém-Nascido , Fígado/irrigação sanguínea , Fígado/diagnóstico por imagem , Masculino , TrissomiaRESUMO
Approaches to cancer therapy for most tumors in adults and children have changed little in 50 years: surgery, radiation, and chemotherapy are standard for many solid tumors. When the concept of angiogenesis in cancer biology was introduced in the 1970s, there was little recognition of the therapeutic potential of attacking a tumor's blood supply. Advances in understanding the molecular processes that regulate tumor blood supply and novel agents that can interfere with them have generated a great deal of scientific interest and excitement. This article reviews the current understanding of angiogenesis and its role in cancer then discusses new therapeutic options in animals and humans, with a focus on pediatric tumors and the potential for treating them.
Assuntos
Inibidores da Angiogênese/uso terapêutico , Neoplasias/irrigação sanguínea , Neovascularização Patológica/tratamento farmacológico , Animais , Ensaios Clínicos como Assunto , Humanos , Neoplasias/tratamento farmacológicoRESUMO
OBJECTIVE: To describe neuropsychological functioning (with a specific focus on cognition and memory) after surgical treatment of craniopharyngiomas. METHODS: Sixteen patients who were between 6 and 15 years of age at the time of surgery comprised the sample. Each child had been treated for a craniopharyngioma with surgery only, on Dana-Farber Cancer Institute Protocol 92-077. RESULTS: The overall level of cognitive functioning was well within the average range, with both language and visuospatial functioning being generally intact; however, specific memory problems, in both the language and visuospatial domains, were evident. CONCLUSION: Although general cognitive functioning was intact after the surgical treatment of craniopharyngiomas, difficulties in the retrieval of learned information were observed. Neuropsychological assessments, with a focus on memory recall, should be a component of the medical management plan for each child.
Assuntos
Craniofaringioma/cirurgia , Transtornos da Memória/diagnóstico , Testes Neuropsicológicos , Neoplasias Hipofisárias/cirurgia , Complicações Pós-Operatórias/diagnóstico , Adolescente , Criança , Feminino , Seguimentos , Humanos , Masculino , Transtornos da Memória/psicologia , Complicações Pós-Operatórias/psicologiaRESUMO
OBJECTIVE: To study the risk factors for the development of moyamoya syndrome after cranial irradiation for primary brain tumors in children. METHODS: We reviewed neuroimaging studies and dosimetry data for 456 children who were treated with radiation for a primary brain tumor and who were prospectively evaluated with serial neuroimaging studies and neurologic evaluations. A total of 345 patients had both adequate neuroimaging and radiation dosimetry data for further analysis. We used survival analysis techniques to examine the relationship of clinically important variables as risk factors for the development of moyamoya over time. RESULTS: Overall, 12 patients (3.5%) developed evidence of moyamoya. The onset of moyamoya was more rapid for patients with neurofibromatosis type 1 (NF1) (median of 38 vs 55 months) and for patients who received >5,000 cGy of radiation (median of 42 vs 67 months). In a multiple Cox proportional hazards regression analysis controlling for age at start of radiation, each 100-cGy increase in radiation dose increased the rate of moyamoya by 7% (hazard ratio [HR] = 1.07, 95% CI: 1.02 to 1.13, p = 0.01) and the presence of NF1 increased the rate of moyamoya threefold (HR = 3.07, 95% CI: 0.90 to 10.46, p = 0.07). CONCLUSIONS: Moyamoya syndrome is a potentially serious complication of cranial irradiation in children, particularly for those patients with tumors in close proximity to the circle of Willis, such as optic pathway glioma. Patients who received higher doses of radiation to the circle of Willis and with neurofibromatosis type 1 have increased risk of the development of moyamoya syndrome.
Assuntos
Neoplasias Encefálicas/radioterapia , Artérias Cerebrais/efeitos da radiação , Doença de Moyamoya/epidemiologia , Lesões por Radiação/epidemiologia , Radioterapia/efeitos adversos , Boston/epidemiologia , Artérias Cerebrais/patologia , Artérias Cerebrais/fisiopatologia , Criança , Pré-Escolar , Círculo Arterial do Cérebro/patologia , Círculo Arterial do Cérebro/fisiopatologia , Círculo Arterial do Cérebro/efeitos da radiação , Comorbidade , Relação Dose-Resposta à Radiação , Feminino , Humanos , Incidência , Lactente , Masculino , Neurofibromatose 1/radioterapia , Quiasma Óptico/patologia , Quiasma Óptico/fisiopatologia , Quiasma Óptico/efeitos da radiação , Estudos Prospectivos , Fatores de Risco , Análise de SobrevidaRESUMO
A number of exciting advances have been reported over the past few years in the understanding and treatment of children with brain tumors. The present review highlights many of the publications from this period, focusing on their relevance within the major diagnostic and treatment domains of pediatric oncology (surgery, radiation therapy, chemotherapy, neuropathology, and neuroradiology). Although many of the publications cited provide confirmation of previously reported work, when taken together they form a good framework of the state of the field from the past few years.
Assuntos
Neoplasias do Sistema Nervoso/terapia , Criança , Humanos , Neoplasias do Sistema Nervoso/diagnóstico por imagem , Neoplasias do Sistema Nervoso/tratamento farmacológico , Neoplasias do Sistema Nervoso/patologia , Neoplasias do Sistema Nervoso/radioterapia , Neoplasias do Sistema Nervoso/cirurgia , RadiografiaRESUMO
The ability of an organism to respond to its environment is critical to survival. The mechanisms by which cells recognize and interpret different stimuli vary enormously and can be manifested by proliferation, differentiation, apoptosis, or altered metabolic activity. Recently, a series of signaling cascades was identified that links actions on the cell surface with activation or suppression of transcription. These signals are transmitted via phosphorylation and include the stress-activated protein kinases and the mitogen-activated protein kinases. This review describes these cascades in reference to the hematopoietic cell lineages.
Assuntos
Proteínas Quinases Dependentes de Cálcio-Calmodulina/fisiologia , Sistema Hematopoético/fisiologia , Proteínas Quinases/fisiologia , Transdução de Sinais , Estresse Mecânico , Animais , Células Precursoras Eritroides/fisiologia , Sistema Hematopoético/citologia , Humanos , Linfócitos/fisiologia , Neutrófilos/fisiologia , Concentração Osmolar , LevedurasRESUMO
Success in the treatment of pediatric brain tumors has lagged behind that of other pediatric cancers. This paper highlights many of the advances that have taken place over the past few years in the surgical, radiotherapeutic, and chemotherapeutic approaches to central nervous system lesions that we hope will lead to a dramatic improvement in outcome. Innovations in neurosurgical and radiotherapeutic techniques have resulted in decreasing toxicity although substantial improvement in cure rates has not been observed. Many new techniques such as gene therapy, angiogenesis inhibitors, immunotherapy, and others that have not been part of the classic approach to these lesions are now in clinical trials in the hope that they will impact on the survival of these patients. The scientific basis for these new treatment modalities and preliminary clinical results are discussed.
Assuntos
Neoplasias Encefálicas/terapia , Criança , HumanosRESUMO
Many malignant tumors demonstrate a definite propensity for metastasis to specific organs despite the fact that tumor cells with the potential for metastasis may circulate randomly throughout the body. Current concepts of organ specific metastasis (OSM) center around the generation of tumor cell variants with enhanced capacity for metastasis to specific organs. At present three hypotheses, mechanical, seed and soil, and specific tumor cell adherence (STCA), stand out as possible explanations for OSM. These possible mechanisms of OSM are by no means mutually exclusive. Recent efforts to understand OSM have included the selection of organ-specific metastasizing variants from tumor cell lines and an examination of their surface and metastatic properties. OSM-selected cell lines from many different tumor systems have been used to examine the relative contributions of the three mechanisms. While examples of each mechanism have been reported, the relative contributions of each for different tumor systems may differ substantially. Therefore, generalizations about the behavior of tumors based on studies with just a few tumor lines and systems may not be valid. There is substantial evidence that cell surface molecules are important in the process of OSM and homing of lymphocytes to specific lymph nodes. Monoclonal antibodies have been produced against putative cell surface receptors and initial biochemical characterization has begun. There is much evidence that cell surface glycoconjugates can serve as specific recognition structures on normal cells and in addition, may play important roles in OSM. The role of these carbohydrates is discussed. The chick embryo as a model system is discussed as it offers several advantages for the study of metastasis in general and OSM in particular. A variety of human and murine tumors, including some freshly isolated, have been shown to grow and metastasize in these embryos. Furthermore, cell lines which have been selected for OSM in adults show similar patterns of metastasis in chick embryos indicating that this system may be an especially attractive one for the analysis of OSM.
Assuntos
Metástase Neoplásica/patologia , Neoplasias/patologia , Animais , Anticorpos/fisiologia , Antígenos de Neoplasias/imunologia , Antígenos de Superfície/imunologia , Aves , Carboidratos/fisiologia , Linhagem Celular , Embrião de Galinha , Modelos Biológicos , Neoplasias/imunologia , Especificidade de Órgãos , FenótipoRESUMO
The phenomenon of "homing" is discussed with respect to patterns of lymphocyte circulation and the molecules on the surface of both endothelium and lymphocytes that mediate this process. In addition, the data are analysed in the context of a model for lymphocyte homing.
Assuntos
Sistema Linfático/imunologia , Linfócitos/imunologia , Animais , Formação de Anticorpos , Antígenos de Superfície/imunologia , Linfócitos B/metabolismo , Cobaias , Humanos , Sistema Imunitário/fisiologia , Camundongos , Ratos , Receptores de Antígenos/metabolismo , Linfócitos T/metabolismoRESUMO
The interaction of the hormone erythropoietin and its receptor (EpoR) is though to be required for normal hematopoiesis. To define the role of EpoR in this process, the murine EpoR was disrupted by homologous recombination. Mice lacking the EpoR died in utero at embryonic day 11-12.5 with severe anemia. Embryonic erythropoiesis was markedly diminished, while fetal liver hematopoiesis was blocked at the proerythroblast stage. Other cell types known to express EpoR, including megakaryocytes, mast, and neural cells were morphologically normal. Reverse transcription-coupled PCR analysis of RNA from embryonic yolk sac, peripheral blood, and fetal liver demonstrated near normal transcripts levels for EKLF, thrombopoietin (Tpo), c-MPL, GATA-1, GATA-2, and alpha- and embryonic beta H1-globin but non for adult beta maj-globin. While colony-forming unit-erythroid (CFU-E) and burst-forming unit-erythroid (BFU-E) colonies were not present in cultures derived from EpoR-/- liver or yolk sac cells, hemoglobin-containing BFU-E colonies were detected in cultures treated with recombinant Tpo and Kit ligand or with Tpo and interleukin 3 and 11. Rescued BFU-E colonies expressed adult beta-globin and c-MPL and appeared morphologically normal. Thus, erythroid progenitors are formed in vivo in mice lacking the EpoR, and our studies demonstrate that a signal transmitted through the Tpo receptor c-MPL stimulates proliferation and terminal differentiation of these progenitors in vitro.
Assuntos
Células Precursoras Eritroides/efeitos dos fármacos , Receptores da Eritropoetina/deficiência , Trombopoetina/farmacologia , Animais , Sequência de Bases , Sangue/metabolismo , Diferenciação Celular/efeitos dos fármacos , Embrião de Mamíferos/citologia , Expressão Gênica , Fígado/embriologia , Fígado/metabolismo , Camundongos , Camundongos Mutantes , Dados de Sequência Molecular , Receptores da Eritropoetina/genéticaRESUMO
Vertebrate hematopoietic stem cells are derived from vental mesoderm, which is postulated to migrate to both extra- and intraembryonic positions during gastrula and neurula stages. Extraembryonic migration has previously been documented, but the origin and migration of intraembryonic hematopoietic cells have not been visualized. The zebrafish and most other teleosts do not form yolk sac blood islands during early embryogenesis, but instead hematopoiesis occurs solely in a dorsal location known as the intermediate cell mass (IM) or Oellacher. In this report, we have isolated cDNAs encoding zebrafish homologs of the hematopoietic transcription factors GATA-1 and GATA-2 and have used these markers to determine that the IM is formed from mesodermal cells in a posterior-lateral position on the yolk syncytial layer of the gastrula yolk sac. Surprisingly, cells of the IM then migrate anteriorly through most of the body length prior to the onset of active circulation and exit onto the yolk sac. These findings support a hypothesis in which the hematopoietic program of vertebrates is established by variations in homologous migration pathways of extra- and intraembryonic progenitors.
Assuntos
Células-Tronco Hematopoéticas , Peixe-Zebra/embriologia , Sequência de Aminoácidos , Animais , Biomarcadores , Clonagem Molecular , DNA Complementar/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/isolamento & purificação , Fatores de Ligação de DNA Eritroide Específicos , Fator de Transcrição GATA1 , Fator de Transcrição GATA2 , Gástrula , Mesoderma , Dados de Sequência Molecular , Fatores de Transcrição/genética , Fatores de Transcrição/isolamento & purificação , Proteínas de Peixe-ZebraRESUMO
Genome-wide chemical mutagenesis screens in the zebrafish (Danio rerio) have led to the identification of novel genes affecting vertebrate erythropoiesis. In determining if this approach could also be used to clarify the molecular genetics of myelopoiesis, it was found that the developmental hierarchy of myeloid precursors in the zebrafish kidney is similar to that in human bone marrow. Zebrafish neutrophils resembled human neutrophils, possessing segmented nuclei and myeloperoxidase-positive cytoplasmic granules. The zebrafish homologue of the human myeloperoxidase (MPO) gene, which is specific to cells of the neutrophil lineage, was cloned and used to synthesize antisense RNA probes for in situ hybridization analyses of zebrafish embryos. Granulocytic cells expressing zebrafish mpo were first evident at 18 hours after fertilization (hpf) in the posterior intermediate cell mass (ICM) and on the anterior yolk sac by 20 hpf. By 24 hpf, mpo-expressing cells were observed along the ICM and within the developing vascular system. Thus, the mpo gene should provide a useful molecular probe for identifying zebrafish mutants with defects in granulopoiesis. The expression of zebrafish homologues was also examined in 2 other mammalian hematopoietic genes, Pu.1, which appears to initiate a commitment step in normal mammalian myeloid development, and L-Plastin, a gene expressed by human monocytes and macrophages. The results demonstrate a high level of conservation of the spatio-temporal expression patterns of these genes between zebrafish and mammals. The morphologic and molecular genetic evidence presented here supports the zebrafish as an informative model system for the study of normal and aberrant human myelopoiesis. (Blood. 2001;98:643-651)