PubMed Health⌕ Search

Biomedical subjects

O Alabaster

Publications and source records attributed to O Alabaster.

At least 37 records · Page 2Linked to original sources
PubMed1986

Expression of surface antigens during the cell cycle in different growth phases of American and African Burkitt's lymphoma cell lines.

We have studied the expression of five surface antigens in eight Burkitt's lymphoma cell lines during different phases of the cell cycle and in different growth phases (logarithmic and stationary). Cells were stained simultaneously for surface antigens (fluorescein coupled antibodies) and DNA content (propidium iodide), and dual parameter measurements were performed with a flow cytometer. Analysis of cells in specific cell cycle phases during log-phase growth revealed a 1.6-fold increase in surface antigen expression as cells passaged from G1 to G2/M. This is almost identical to the measured increase in cell surface area which occurs during passage of cells through the cell cycle and indicates that under optimal conditions surface antigen density is maintained during cell doubling. We also observed a consistent reduction, by about 50%, in the expression of surface IgM (mu), k-light chain, and B1 on the cell lines during a 5-day culture period. Cell lines that only weakly expressed surface IgM were found to have a more rapid decrease, and in such cell lines IgM was ultimately completely lost from the cell surface. In contrast, the expression of beta 2-microglobulin and HLA-ABC increased in some cell lines, whereas in others a significant decrease of both beta 2-microglobulin and HLA expression was demonstrated as the cells entered stationary growth phase. Decreased cell volume (and therefore surface area) associated with declining growth rate and fewer late S or G2/M cells could account for 20-30% of the observed reduction in surface IgM, k-light chain, and B1 expression, but the major decrement in fluorescence intensity was due to a reduction in the density of these surface antigens. Thus, the ability to maintain surface antigen densities is frequently lost in suboptimal culture conditions.

Africa↗
PubMed1985

T-cell abnormalities after mediastinal irradiation for lung cancer. The in vitro influence of synthetic thymosin alpha-1.

The effects of mediastinal irradiation (RT) on the numbers and functions of purified peripheral blood T-lymphocytes from patients with locally advanced non-small cell lung cancer were evaluated. The patients were candidates for a randomized trial to evaluate the immunorestorative properties of synthetic thymosin alpha-1. Twenty-one patients studied before RT did not exhibit any significant difference in T-cell numbers or function compared to age-matched healthy subjects. However, 41 patients studied within 1 week after completing RT exhibited significant depressions of E-rosette-forming cells at 4 degrees C (E4 degrees-RFC)/mm3, E-rosette-forming cells at 29 degrees C (E29 degrees-RFC)/mm3, OKT3/mm3, OKT4/mm3, and OKT8/mm3 (P = 0.0001); total T-cell percentages (%OKT3, P = 0.01); and T-cell proliferative responses in mixed lymphocyte cultures (MLR) (P = 0.01) and to the mitogen phytohemagglutinin under suboptimal conditions (P less than or equal to 0.03). Nine patients studied before and after RT showed a significant increase in OKT4/OKT8 (P = 0.01) following RT. A short-term in vitro incubation with thymosin alpha-1 could enhance MLR of T-cells in 12 of 27 patients with post-RT abnormalities. In 13 patients who were treated with placebo, the RT-induced depression of T-cell numbers and function persisted for at least 3 to 4 months. In addition, in 12 patients progressive decreases developed in %E4 degrees-RFC, %OKT3, %OKT4, and OKT4/OKT8, which always preceded clinical relapse. This study indicates that mediastinal RT results in prolonged depletion of circulating T-cells, alterations of T-cell subset proportions, and intrinsic T-cell functional deficiencies. This patient population provides a uniformly immunosuppressed group of subjects with which to evaluate the immunorestorative effects of thymosin alpha-1 or other biologic response modifiers.

Adult↗
PubMed1985

Phenotypic and ultrastructural characterization of a medullary thymocyte acute lymphoblastic leukemia with cellular procoagulant activity.

The phenotypic and ultrastructural characterization of the blast cells from a T-cell acute lymphoblastic leukemia (T-ALL) that was associated with disseminated intravascular coagulation (DIC) is described. The bone marrow blasts were considered to represent neoplastic medullary thymocytes and were acid phosphatase (+), terminal deoxynucleotidyl transferase (-), acid alpha-naphthyl acetate esterase (-), E-rosette (+) at 4 degrees C and 37 degrees C, Fc- and C3-receptor (-), and cALLA-, Ia-, 9.6+, OKT3+, OKT4+, OKT6+/-, OKT8+, OKT10+. On transmission electron microscopic study, the predominant cell was 6 micron in diameter and possessed an irregular nucleus, moderate-sized nucleolus, marginated heterochromatin, abundant Golgi elements and granules, and prominent intermediate filaments. The cells were analyzed with normal and factor-deficient human plasmas and contained significant amounts of tissue factor-like procoagulant activity. This is the first report of a well-characterized medullary thymocyte T-ALL in which DIC was an accompanying feature, and the first demonstration of tissue factor-like procoagulant activity in acute lymphoblastic leukemia. In view of thrombohemorrhagic phenomena observed in association with other medullary thymocyte leukemias, these findings suggest that tissue factor-like procoagulant activity may be a characteristic of medullary thymocyte-derived lymphoid leukemias.

Acute Disease↗
PubMed1985

pH dependence of mitomycin C-induced cross-linking activity in EMT6 tumor cells.

Mitomycin C (MC), a quinone-containing bioreductive alkylating agent, is cytotoxic to aerobic EMT6 tumor cells despite the fact that little bioactivation of MC occurs in EMT6 cell homogenates in the presence of O2. Because spontaneous activation of MC at acidic pH has been reported in chemical systems, aerobic EMT6 tumor cells were incubated in serum-free 2-(N-morpholino)ethanesulfonic acid or N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer at pH 5.7, 6.4, and 7.5 and exposed to MC for 2 h. As the extracellular pH was lowered, MC-induced DNA-DNA cross-linking, as measured by alkaline elution techniques, was enhanced. This effect was dose dependent at the three pH values tested. Measurement of intracellular pH by flow cytometric analysis indicated that the decrease in extracellular pH was paralleled by a fall in intracellular pH. The alteration of the extracellular pH had no effect on the colony-forming ability of control cells. The survival of cells treated with MC, however, was decreased as the pH was lowered. These data suggest that the intracellular and/or the extracellular pH is an important determinant of MC activity in aerobic EMT6 tumor cells.

Animals↗
PubMed1985

A randomized trial to evaluate the immunorestorative properties of synthetic thymosin-alpha 1 in patients with lung cancer.

A randomized trial was performed in 42 postradiotherapy patients with non-small cell lung cancer to determine whether the administration of synthetic thymosin-alpha 1 by either a loading dose or a twice-weekly schedule could accelerate the reconstitution of thymic dependent immunity. The radiotherapy-induced immunosuppression was characterized by an absolute T cell lymphopenia and by impaired T cell function in lymphoproliferative assays. Placebo-treated patients did not show any improvement in T cell numbers or function over 15 weeks of serial immune monitoring, and exhibited gradual depressions of helper T lymphocyte percentages. Patients treated with thymosin by the loading dose regimen exhibited a normalization of T cell function (p = 0.04), whereas patients treated with the twice-weekly schedule maintained normal helper T cell percentages (p = 0.04). Thymosin treatment was associated with significant improvements in relapse-free and overall survival, which was most pronounced for patients with nonbulky tumors. Thymosin-alpha 1 exhibits schedule-dependent immune restorative and homeostatic properties. Large scale Phase III trials are indicated to definitively establish the impact of thymosin therapy in lung cancer patients treated with radiotherapy.

Adjuvants, Immunologic↗
PubMed1984

Inverse correlation between age related abnormalities of T-cell immunity and circulating thymosin alpha 1 levels in haemophilia A.

T-cell immunity and serum levels of thymosin alpha 1, beta 2-microglobulin, circulating immune complexes, serum immunoglobulin levels, antibodies to hepatitis surface or core antigen, and to cytomegalovirus, and Epstein-Barr virus were investigated in 51 patients with haemophilia A ranging in age from 2 to 52 years. All patients had received commercial U.S. lyophilized concentrates of antihaemophilic factor (AHF). The mean helper/cytotoxic-suppressor (OKT4/OKT8) ratio of 11 pre-adolescents (1.6 +/- 0.4 SE) was not significantly different from that of age matched normal controls. In contrast, the mean OKT4/OKT8 ratios of 13 adolescent (1.2 +/- 0.2 SE) and 23 adult (0.8 +/- 0.1 SE) haemophiliacs were significantly reduced. Abnormalities of lymphocyte mitogenic responses were found only in adult haemophiliacs. Nine individuals treated with commercial U.S. prothrombin complex concentrates for antibodies directed against AHF or for haemophilia B had normal mean OKT4/OKT8 values. The mean serum thymosin alpha 1 levels for each age category was similar to that of age matched controls; however, regression analysis revealed a significant relationship between elevated thymosin alpha 1 levels and decreased OKT4/OKT8 ratios in adult haemophiliacs (P = 0.012). Although the mean serum level of beta 2-microglobulin was significantly increased in the adult haemophiliac group, there was no correlation between OKT4/OKT8 ratios and any of the other serologic parameters studied.

Adolescent↗
PubMed1983

Synthesis of kappa light chains by cell lines containing an 8;22 chromosomal translocation derived from a male homosexual with Burkitt's lymphoma.

Three cell lines were derived from a homosexual patient with probable acquired immunodeficiency syndrome and Burkitt's lymphoma. The cell lines produce an unusual strain of Epstein-Barr virus which will both transform cord blood lymphocytes and induce early antigens in Raji cells. Translocations between chromosomes 8 and 22 have occurred in all three lines, but the cells synthesize immunoglobulin M with light chains of the kappa type, in contrast to the usual concordance between a translocation involving chromosome 22 and lambda chain synthesis. Both kappa genes and one lambda gene are rearranged. These findings indicate either that translocation may occur as a separate event from immunoglobulin gene rearrangement or that the proposed hierarchical sequence of immunoglobulin gene rearrangements is not always adhered to. The data also imply that in cells containing a translocation between the long arm of chromosome 8 and a chromosome bearing an immunoglobulin gene, alteration of cellular myc expression may occur regardless of the immunoglobulin gene that is expressed.

Acquired Immunodeficiency Syndrome↗
PubMed1981

Collagen heterogeneity in normal human bone marrow.

Paraffin embedded sections of formalin fixed, decalcified, normal, human, vertebral bone were stained immunohistochemically for collagen types I, III and IV using the peroxidase--anti-peroxidase (PAP) technique. Preparations stained for collagen types I and III were virtually identical in appearance. These substrates were localized to the cytoplasm and fibrillar processes of a population of cells which were sparsely distributed within the haemopoietic compartment of the bone marrow, being particularly prominent in relation to the marrow sinusoids and fat spaces. They would thus appear to parallel the known distributions of reticulum cells, although their morphology differed in some respects from classical descriptions of the latter cell type. Type IV collagen was found in association with the endothelial lining of the sinusoids. Other connective tissue elements (bone, periosteum, endosteum, blood vessels, etc.) showed characteristic collagen heterogeneity. These results indicate that collagen is a significant component of the bone marrow connective tissue.

Antibodies↗
PubMed1981

Phagocytic properties of bone marrow fibroblasts.

Phagocytic activity has been observed in cultured marrow derived adherent cells (MDAC). Characterization studies indicate that these populations consist largely of collagen-producing fibroblasts, having failed to reveal markers associated with mononuclear phagocytes (MNP). Phagocytic activity by MDAC was therefore investigated. Characterization studies again failed to demonstrate an Fc receptor and confirmed that human MDAC synthesize collagen in vitro. Phagocytic activity against polystyrene microspheres was observed in 40% of MDAC. Control studies using P-8 and WI-38 fibroblasts yielded similar results. MDAC, P-8 and WI-38 fibroblasts were exposed to fluorescent microspheres and subsequently stained by immunofluorescence for type I collagen. Many cells were seen both to contain fluorescent particles and to stain positively for type I collagen. These results indicate that marrow derived fibroblasts, in common with fibroblasts from other sources, have phagocytic capability under appropriate conditions.

Bone Marrow Cells↗
PubMed1981

Induction of complement receptors in human cell lines derived from undifferentiated lymphomas.

Two Epstein-Barr nuclear antigen-negative cell lines, EW36 and CA46, derived from human undifferentiated lymphomas were exposed to the methylxanthines theophylline and 3-isobutyl-1-methylxanthine. Both compounds markedly increased the proportion of cells which bears complement receptors, whereas other surface markers such as surface immunoglobulin and IgG Fc receptors were unchanged. The inducing agents, hexamethylene bisacetamide and diethylsulfoxide, had a similar effect, but other compounds known to alter intracellular cyclic AMP had no effect on surface markers. The expression of complement receptors first appeared at 8 to 10 hours and was dependent upon the continued presence of theophylline in the tissue culture medium. Other effects of the methylxanthine derivatives tested included inhibition of DNA synthesis and a reduction in mean cellular volume. However, inhibition of growth per se did not result in complement receptor induction. These data suggest that the differentiation agents active in this system may be useful tools in the study of human lymphoid malignancies.

Cell Differentiation↗
PubMed1981

Analysis of NZB hyperdiploid spleen cells.

In order to study the cell types involved in the hyperdiploidy characteristic of NZB mice, flow cytometric techniques, which measure te DNA content of individual cells, have been used together with standard cytogenetic analysis. The aneuploid cells present in NZB mice were found to be clonally derived. These cells were of large size relative to nonaneuploid cells. They could not be removed by lysis with anti-Thy 1 plus complement nor were they present in the nylon-wool column nonadherent fraction, both of which are characteristic of T cells. By further cytotoxic analysis, the aneuploid cells were found not to express Ly-5 nor NK surface antigens, found on natural killer cells. The aneuploid cells had increased quantities of cell surface H-2 antigen. This marked susceptibility to lysis with anti-H-2 serum was associated with one or more extra copies of chromosome 17, which carries the H-2 complex. A large proportion of these cells also expressed surface Ia and Ig. The aneuploid cells found in the spleens of older NZB mice derive from bone marrow stem cells. Neonatally thymectomized and lethally irradiated NZB X DBA/2 recipients of anti-Thy-1 treated young NZB bone marrow cells ultimately developed aneuploid spleen cells. Such cells are not found in intact or thymectomized NZB Z DBA/2 mice nor in recipients of DBA/2 marrow. Finally, congenic NZB mice carrying the CBZ/N xid failed to develop aneuploidy. Taken together, these studies suggest that the aneuploid cell is a bone marrow-derived stem cell destined to differentiate into the B cell subset lacking in CBA/N mice.

Aneuploidy↗
PubMed1980

Analysis of the proliferation kinetics of Burkitt's lymphoma cells.

The in vitro proliferation kinetics of a cell line derived from a patient with American Burkitt's lymphoma were investigated at three different growth phases: lag (day 1), exponential (day 3) and plateau (day 5). The growth curve, labeling and mitotic indices, percentage labeled mitosis (PLM) curves and DNA content distributions were determined. The data obtained have been analysed by the previously developed discrete-time kinetic (DTK) model by which a time course of DNA distributions during a 10-day growth period was characterized in terms of other cell kinetic parameters. The mean cell cycle times, initially estimated from PLM curves on days 1, 3 and 5, were further analysed by the DTK model of DNA distributions and subsequently the mean cell cycle times with respect to DNA distributions during the entire growth period were determined. The doubling times were 39.6, 31.2 and 67.2 hr, respectively, at days 1, 3 and 5. The mean cell cycle time increased from 23.0 to 37.7 hr from day 3 to day 5 mainly due to an elongation of the G1 and G2 phases. A slight increase in the cell loss rate from 0.0077 to 0.0081 fraction/hr was accompanied by a decrease in the cell production rate from 0.0299 to 0.0184 fraction/hr. This calculated cell loss rate correlated significantly with the number of dead cells determined by trypan blue exclusion. Analysis of the number of dead cells in relation to the cell cycle stage revealed that a majority of cell death occurred in G1 (r + 0.908; P < 0.0001). There was a good correlation between the in vitro proliferation kinetics at plateau phase of this Burkitt's lymphoma derived cell line and the in vivo proliferation kinetics of African Burkitt's lymphoma (Iversen et al., 1974), suggesting the potential utility of information obtained by in vitro kinetic studies.

Burkitt Lymphoma↗
PubMed1980

Electrolytic degradation of DNA fluorochromes during flow cytometric measurement of electronic cell volume.

Changes in flow cytometric measurement of DNA content can result from electrolytic chemical degradation of mithramycin, ethidium bromide, and propidium iodide during simultaneous measurement of electronic cell volume. Bench electrolysis also degrades these fluorochromes without changing the quantum yields, even when they are complexed to DNA. In the flow cytometer, electrolytic production of chlorine at the anode is the probable cause of this degradation, since exposure of these fluorochromes to chlorine gas produces the same effect. It is therefore advisable to measure the DNA content distribution alone before simultaneously measuring the DNA content and the electronic cell volume. If unavoidable effects on the DNA distribution are present, narrow forward-angle light scatter should be used as the cell size indicator during dual parameter measurements. Modifying instrument design by reversing electrode polarity might eliminate this problem.

Cytological Techniques↗
PubMed1980

Characterization of lymphoma-derived cell lines: comparison of cell lines positive and negative for Epstein-Barr virus nuclear antigen. I. Physical, cytogenetic, and growth characteristics.

Sixteen lymphoid cell lines were derived from patients with undifferentiated lymphoma of Burkitt's or non-Burkitt's type. They were obtained directly from tumor biopsies, from serous effusions, or from bone marrow. In 10 of the cell lines, the Epstein-Barr virus (EBV) nuclear antigen (EBNA) was undetectable; the remaining 6 lines were EBNA-positive (EB-pos). Of the 16 lines, 15 were aneuploid, with detectable chromosome "14q+ markers (11 had +8;14 translocations). These 15 lines, which included the EBNA-negative (EB-neg) lines, were believed to be of tumor cell origin. The remaining line consisted predominantly of diploid cells derived from normal lymphocytes, but some cells of tumor origin were present. Four EB-pos cell lines derived from EB-neg tumors had an aneuploid karyotype consistent with an origin from tumor cells (including no.8;14 translocation in two), which suggested that either tumor cells were infected with EBV in vitro or a tiny fraction of EB-pos tumor cells (or potential tumor cells) present in vivo gave rise to the predominant cell of the line. EB-neg B-cell lines and EB-pos cell lines established from undifferentiated lymphomas differed greatly. EB-neg lines had consistently smaller electronic mean cell volumes and narrow-angle light scatter than did EB-pos lines. This finding correlated with a lower nuclear:cytoplasmic ratio in EB-pos lines. EB-neg lines also had higher saturation cell densities than did EB-pos lines under standard culture conditions. The data indicate either that EBV influences the morphologic and physiologic characteristics of lymphoid cell lines or that EB-neg B-cell lines and EB-pos cell lines are derived ultimately from different lymphocyte subpopulations or that both may apply.

Antigens, Viral↗