Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
Más filtros











Base de datos
Intervalo de año de publicación
1.
J Chem Phys ; 136(1): 014301, 2012 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-22239775

RESUMEN

A beam of rotating dipolar particles (molecules or clusters) will broaden when passed through an electric or magnetic field gradient region. This broadening, which is a common experimental observable, can be expressed in terms of the variance of the distribution of the resulting polarization orientation (the direction cosine). Here, the broadening for symmetric-top and linear rotors is discussed. These two types of rotors have qualitatively different low-field orientation distribution functions, but behave similarly in a strong field. While analytical expressions for the polarization variance can be derived from first-order perturbation theory, for experimental guidance it is important to identify the applicability and limitations of these expressions, and the general dependence of the broadening on the experimental parameters. For this purpose, the analytical results are compared with the full diagonalization of the rotational Stark-effect matrices. Conveniently for experimental estimations, it is found that for symmetric tops, the dependence of the broadening parameter on the rotational constant, the axial ratio, and the field strength remains similar to the analytical expression even outside of the perturbative regime. Also, it is observed that the shape envelope, the centroid, and the width of the orientation distribution function for a symmetric top are quite insensitive to the value of its rotational constant (except at low rotational temperatures).

2.
J Chem Phys ; 129(2): 024101, 2008 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-18624510

RESUMEN

The induced polarization of a beam of polar clusters or molecules passing through an electric or magnetic field region differs from the textbook Langevin-Debye susceptibility. This distinction, which is important for the interpretation of deflection and focusing experiments, arises because instead of acquiring thermal equilibrium in the field region, the beam ensemble typically enters the field adiabatically, i.e., with a previously fixed distribution of rotational states. We discuss the orientation of rigid symmetric top systems with a body-fixed electric or magnetic dipole moment. The analytical expression for their "adiabatic-entry" orientation is elucidated and compared with exact numerical results for a range of parameters. The differences between the polarization of thermodynamic and "adiabatic-entry" ensembles of prolate and oblate tops, and of symmetric top and linear rotators, are illustrated and identified.

3.
Leuk Res ; 25(2): 141-9, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11166829

RESUMEN

Hematopoietic progenitor cell differentiation is associated with the expression of different sets of genes including those encoding membrane bound molecules and cytokines. While expression of the former has meticulously been linked to both lineage specificity and maturation stages and is routinely used in the diagnosis of human leukemias, the production of cytokines has not systematically been analyzed in this respect. Secretion of cyto- and chemokines by HPC has been discussed as a key element of autocrine regulation of cell differentiation and proliferation in normal and malignant hematopoietic cells. Hematopoietic cell lines and their in vitro generated mature progeny were used as a model to investigate the cytokine and chemokine expression pattern prior to and after induction of differentiation. We show that a variety of cytokines are produced by these cells either constitutively or upon stimulation. Low levels of TNF-alpha and IL-8 were widely expressed by immature and mature cells, while peak values of TNF-alpha were detected in promyelocytic NB4 cells, as reported previously. Induction of monocytic differentiation by various agents was associated with upregulation of IL-1 beta and IL-1ra expression, while a differentiation shift to the granulocytic lineage in the presence of retinoic acid (RA) led to a marked increase of macrophage chemoattractant protein-1 (MCP-1) producing cells. These data indicate that lineage determination as well as maturation of hematopoietic cells may not only be associated with expression of specific surface molecules but also with a distinct cytokine expression pattern. Further studies are necessary to show if this holds true for primary leukemic and normal hematopoietic cells.


Asunto(s)
Quimiocinas/genética , Citocinas/genética , Diferenciación Celular/efectos de los fármacos , Línea Celular , Granulocitos/citología , Granulocitos/efectos de los fármacos , Humanos , Inmunofenotipificación , Monocitos/citología , Monocitos/efectos de los fármacos
4.
Br J Haematol ; 97(1): 9-14, 1997 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9136936

RESUMEN

In vitro expansion of haemopoietic progenitor cells (HPC), lineage-specific differentiation, and gene transfer are all based on in vitro culture systems using haemopoietic growth factors (HGF). A close control of the actual culture conditions, however, is difficult due to secondary mediators secreted by the heterogenous population of mature and immature cells in culture. Although monocytes and granulocytes have already been identified as active producers, this study specifically addressed the role of CD34+ progenitor cells in this respect. Using an immunostaining method that enables simultaneous detection of cytokines and phenotype, 56 +/- 6% CD34+ peripheral blood progenitor cells (PBPC) were found to contain cytoplasmic IL-8 after stimulation with phorbol myristate acetate + ionomycin for 90 min. 19 +/- 40%, stained positive after TNF-alpha induction (20 h), and 7 +/- 1% expressed IL-8 in the presence of culture medium alone. Intra-cytoplasmic TNF-alpha and IL-1beta were detected at lower frequency, and < 1% of CD34+ cells expressed IL-1ra or IL-6, whereas IL-1alpha, IL-10 and G-CSF were not detected. Thus, CD34+ HPC are able to synthesize chemo- and cytokines that may operate in an auto- or paracrine manner to modulate in vivo as well as in vitro growth and differentation of haemopoietic cells.


Asunto(s)
Quimiocinas/metabolismo , Citocinas/metabolismo , Células Madre Hematopoyéticas/metabolismo , Antígenos CD34 , Humanos , Inmunohistoquímica
5.
Histochem J ; 28(6): 461-6, 1996 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8863051

RESUMEN

The goal of this study was to establish a generally applicable immunoenzymatic method for the simultaneous detection of cytokine and immunophenotype at the single cell level. Evaluating various cell preparations and staining protocols, we found that permeabilization by saponin (0.1%) is very efficient, in combination with glutaraldehyde (0.04%) as fixative. Among various staining procedures, sequential immunoperoxidase labelling of the cytokine by use of diaminobenzidine, and detection of the immunophenotype by use of 4-chloronaphthol proved most discriminative. The typical localization of the cytokine reaction product ('Golgi staining') within the cell, and the 'ring-like' staining for the immunophenotype on the cell surface, allowed precise identification of double-labelled cells. Primary monoclonal antibodies from the same species could be used without loss of sensitivity and specificity for either or both antigens. This method thus provides the opportunity to study morphology, cytokine and immunophenotype simultaneously at the single cell level with standard equipment. Its application for the analysis of tissue samples is in progress, and may allow us to incorporate the cytokine-type as a new parameter in histopathological diagnostics.


Asunto(s)
Citocinas/análisis , Técnicas de Preparación Histocitológica , Inmunofenotipificación/métodos , Monocitos/química , Adulto , Animales , Anticuerpos Monoclonales/análisis , Antígenos CD/análisis , Células Cultivadas , Humanos , Técnicas para Inmunoenzimas , Ratones , Monocitos/citología , Ratas , Valores de Referencia , Linfocitos T/química
6.
Phys Rev B Condens Matter ; 43(6): 4565-4572, 1991 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-9997823
7.
Phys Rev B Condens Matter ; 42(6): 3247-3252, 1990 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-9995837
8.
Phys Rev B Condens Matter ; 40(18): 12507-12508, 1989 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-9991888
9.
Phys Rev B Condens Matter ; 40(8): 5417-5427, 1989 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-9992572
11.
Acta Cytol ; 32(6): 811-5, 1988.
Artículo en Inglés | MEDLINE | ID: mdl-2974226

RESUMEN

The aim of this study was to investigate lymphocyte subpopulations in 17 patients with malignant ascites due to serous papillary adenocarcinoma of the ovary. Eight patients had not been treated prior to the study whereas nine patients had been treated by surgery and chemotherapy. A panel of monoclonal antibodies against surface markers that correlate with the immune functions of the lymphocytes was used. The lymphocyte subpopulations were identified by the immunoperoxidase adhesive slide assay, and the results in treated and untreated patients were compared. Both groups of patients showed lymphocytosis (41 +/- 25% and 33 +/- 14% of the total cells, respectively). The untreated patients had a significantly higher proportion of B cells (14 +/- 4% of lymphocytes) than did treated patients (7 +/- 2%). No differences were found between both groups regarding the helper-inducer/suppressor-cytotoxic T lymphocyte ratio. The proportion of lymphocytes expressing interleukin-2-receptors was higher in treated patients (6 +/- 2%) than in untreated patients (1.2 +/- 1%). Both groups showed a high percentage of natural killer/cytotoxic cells (17 +/- 7% and 18 +/- 5%, respectively). In the only chylous effusion in this study, there was an increase in helper-inducer and activated T lymphocytes. Future studies are required to document whether surface marker analysis of lymphocytes in malignant effusions may be useful for assessment of the prognosis and the results of treatment.


Asunto(s)
Líquido Ascítico/patología , Cistadenocarcinoma/patología , Linfocitos/patología , Neoplasias Ováricas/patología , Adulto , Anciano , Antígenos de Diferenciación/análisis , Linfocitos B/inmunología , Linfocitos B/patología , Cistadenocarcinoma/tratamiento farmacológico , Cistadenocarcinoma/cirugía , Femenino , Antígenos HLA-DR/análisis , Humanos , Técnicas para Inmunoenzimas , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/patología , Activación de Linfocitos , Linfocitos/inmunología , Macrófagos/inmunología , Macrófagos/patología , Persona de Mediana Edad , Neoplasias Ováricas/tratamiento farmacológico , Neoplasias Ováricas/cirugía , Linfocitos T Citotóxicos/inmunología , Linfocitos T Citotóxicos/patología , Linfocitos T Colaboradores-Inductores/inmunología , Linfocitos T Colaboradores-Inductores/patología , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/patología
12.
Phys Rev B Condens Matter ; 38(6): 3741-3746, 1988 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-9946743
13.
Acta Cytol ; 32(4): 519-22, 1988.
Artículo en Inglés | MEDLINE | ID: mdl-3041721

RESUMEN

In 17 malignant peritoneal effusions due to papillary serous adenocarcinoma of the ovary, the reaction patterns of the tumor cells to monoclonal antibodies (MAbs) against surface antigens were studied and compared with the reaction patterns of mesothelial cells in the same effusions. The following surface markers were used with the adhesive slide method: epithelial membrane antigen (EMA), human epithelium-specific cell surface antigen (HEA-125), human endothelial antigen (BMA-120), carcinoembryonic antigen (CEA 3-13), an antibody against natural killer cells and cytotoxic cells (BMA-070), granulocyte antigen (Leu M1) and leukocyte antigen of class I (HLA-1). In all cases, from 30% to 95% of the tumor cells reacted with EMA and HEA-125. Tumor cells showed a positive staining with CEA 3-13 in only five cases. In all cases, from 75% to 95% of the tumor cells reacted positively with BMA-120. The reactivity of a few mesothelial cells with EMA and of all mesothelial cells with BMA-120 did not interfere with the identification of positive tumor cells since the reaction patterns were different. Interestingly, our study demonstrated that BMA-070, an MAb identifying natural killer cells and cytotoxic cells, is also a most useful tumor marker. The same was found to be true for Leu M1, an MAb originally thought to react only with granulocytes. The tumor cells showed a partial or total loss of the expression of HLA-1 reactivity. Since all cases were immunocytochemically positive for tumor cells while conventional cytology was positive in only 13 of the cases, the immunocytochemical analysis of malignant peritoneal effusions due to papillary serous adenocarcinoma of the ovary seems able to improve the cytologic diagnosis of the fluids.


Asunto(s)
Adenocarcinoma Papilar/patología , Líquido Ascítico/patología , Inmunohistoquímica , Neoplasias Ováricas/patología , Anticuerpos Monoclonales , Antígenos de Superficie/inmunología , Antígeno Carcinoembrionario/inmunología , Endotelio/inmunología , Epitelio/inmunología , Femenino , Histocitoquímica , Humanos , Técnicas para Inmunoenzimas
14.
Phys Rev Lett ; 59(16): 1805-1808, 1987 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-10035336
15.
Artículo en Inglés | MEDLINE | ID: mdl-171865

RESUMEN

Immunologically induced T-cell lymphomas were kept for long period fo time in isotransplantation and in tissue culture. Initially, a certain number of cells within the tumor showed differentiation towards histiocytes. These disappeared completely after about the twentieth graft generation when the tumor changed toward a more atypical and more uniform neoplasm. That change was correlated with a decrease in transplantability, a limited growth in tissue culture, and a decrease in density of theta antigens on tumor cell membranes. While the original tumor and early grafts contained occasional C-type particles, these were never demonstrated in late tumor grafts. The possible implications of these changes are discussed.


Asunto(s)
Linfoma no Hodgkin/patología , Linfocitos T/citología , Animales , Diferenciación Celular , División Celular , Células Cultivadas , Femenino , Histiocitos/citología , Cuerpos de Inclusión Viral , Ratones , Ratones Endogámicos BALB C , Trasplante de Neoplasias , Neoplasias Experimentales , Receptores de Antígenos de Linfocitos B/análisis , Retroviridae , Linfocitos T/inmunología , Linfocitos T/ultraestructura , Inmunología del Trasplante , Trasplante Isogénico
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA