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P Agbor

Publications and source records attributed to P Agbor.

8 recordsLinked to original sources
PubMed1996

Probing the pathobiology of response to all-trans retinoic acid in acute promyelocytic leukemia: premature chromosome condensation/fluorescence in situ hybridization analysis.

The response of acute promyelocytic leukemia (APL) peripheral blood and bone marrow cells to trans-retinoic acid (RA) was cytogenetically characterized during RA treatment using the techniques of premature chromosome condensation (PCC) and fluorescence in situ hybridization (FISH). Before treatment, the predominant immature bone marrow cells were found to have t(15;17), whereas the residual mature granulocytes were diploid and lacked evidence of the translocation. In response to RA treatment, an increase in the leukocyte count was noted. The majority of these cells exhibited a t(15;17). Subsequently (eg, between days 6 and 23), 32% to 91% of the maturing myeloid cells still exhibited t(15;17). The appearance of t(15;17) in gradually maturing elements suggests that RA contributed to a release of the maturation block of the leukemic elements. As responding patients obtained complete remission, diploid elements without evidence of the translocation prevailed in the blood and bone marrow. In 16 patients studied after 1 month in complete remission, all but 2 showed all diploid cells. The residual t(15;17) cells disappeared 18 days later in 1 patient, whereas the second patient exhibited clinical evidence of relapse 20 days later. These results suggest that response of patients with APL to RA is associated with maturation, subsequent loss of the mature leukemic elements, and preferential regeneration of normal diploid hematopoietic elements.

Adolescent↗
PubMed1996

Rapid debulking and CD34 enrichment of filgrastim-mobilized peripheral blood stem cells by semiautomated density gradient centrifugation in a closed system.

Filgrastim-mobilized peripheral blood progenitor cells (PBPC) are used for hematopoietic reconstitution after myeloablative therapy for malignancies, but the large number of cells collected in a single apheresis frequently presents a problem for storage or further processing. We have evaluated the use of CD34 Buoyant Density Solution-PBPC, an ultralight-density colloidal silica suspension, for debulking and enrichment of CD34+ cells in PBPC preparations in a semiautomated system. Cells were collected from four filgrastim-treated normal donors using the COBE Spectra. The separation procedure was carried out with Plasma-Lyte A and DNase 5 U/ml using the COBE 2991. Following processing and washing, there was a 26% recovery of nucleated cells, 2.6-fold enrichment of CD34+ cells, 68% recovery of CD34+ cells, 88% recovery of CFU-GM, 73% recovery of BFU-E, 1 log depletion of CD3+ cells, 0.5 log depletion of CD56+ cells, and 1 log depletion of CD19+ cells. These results were not significantly different from those obtained when PBPC were separated over CD34 Buoyant Density Solution-PBPC by centrifugation in tubes. Using CD34 Buoyant Density Solution-PBPC, mononuclear preparations of PBPC can be enriched rapidly for CD34+ cells and depleted of lymphocytes in a semiautomated closed system using reagents produced according to good manufacturing practice (GMP).

Antigens, CD34↗
PubMed1989

Simultaneous cell type identification and premature chromosome condensation analysis in a case of multiple myeloma.

The technique of premature chromosome condensation was combined with immunocytochemical techniques to determine the karyotype of the plasma cells in a patient with multiple myeloma. Although the patient's myeloma cells had a diploid DNA content, the mean chromosome number was 39. Multiple chromosome rearrangements were documented in the G- and C-banded G1 and G2 prematurely condensed chromosomes, and several of these involved telomeric regions resulting in dicentric chromosomes. That the aberrant karyotype was present in the kappa light chain positive plasma cells was proved by simultaneous chromosome analysis and immunocytochemical examination of the fused cells. Thus the combination of premature chromosome condensation and immunocytochemistry proved a powerful tool for cytogenetic analysis of a slow-growing, heterogeneous cell population.

Adult↗
PubMed1988

Improvements in the premature chromosome condensation technique for cytogenetic analysis.

In this paper we report a combination of procedures that serve to improve the usefulness of the technique of premature chromosome condensation in cytogenetic investigations. The mitotic inducer population was preincubated in high concentrations of BrdU, and the duration of fusion was increased to yield more discrete prematurely condensed chromosomes (PCC). After fusion, chromosome preparations were treated with a combination of G- or C-banding techniques and differential staining techniques. This combination of procedures allowed unequivocal distinction between the PCC and mitotic inducer chromosomes and yielded banded G1 and G2 PCC suitable for routine cytogenetic investigations.

Animals↗
PubMed1988

Detection of leukemic clone maturation in vivo by premature chromosome condensation.

The purpose of this study was to determine the feasibility of using the technique of premature chromosome condensation to detect the in vivo maturation of abnormal elements in patients with chronic myelogenous leukemia (CML), myelodysplastic syndrome, and acute leukemia. Patients were chosen for study if there were a clinical suggestion of in vivo maturation and a leukemic clone exhibiting a distinguishable karyotypic abnormality. Mature peripheral blood granulocytes were enriched by two-step Ficoll-Hypaque gradient sedimentation and fused with mitotic Chinese hamster ovary cells to induce the formation of prematurely condensed chromosomes (PCC). These PCC were then analyzed for chromosome number per cell (in the case of patients with a numerical abnormality) or by G-banding (in the case of specific translocations). Of 13 patients chosen for study, 12 showed karyotypic evidence for maturation of the abnormal elements in vivo. Maturation was observed in a number of clinical situations including before treatment in benign CML and myelodysplasia, after low-dose and high-dose chemotherapy in myelodysplasia and acute myelogenous leukemia (AML), and in remission. These results suggest that the technique of premature chromosome condensation can be a powerful tool in better understanding the biology of disease and mode of response to therapy in vivo in patients with leukemia and preleukemic syndromes, especially during treatment with agents thought to induce maturation of the leukemic elements.

Aneuploidy↗
PubMed1986

Estrogens and Chlamydia trachomatis.

Isolates of Chlamydia trachomatis were inoculated in nonreplicating McCoy cells and incubated for 48 hr with various concentrations of hormones. Only the estrogens, particularly 17-beta-estradiol, had an affect on the subsequent infection of the McCoy cells by the Chlamydia. Exposure to 2-4 ng/ml (10(-8) M) estradiol during inoculation and incubation was associated with no change in the initial binding of Chlamydia to McCoy cells, but significantly more (about twofold) Chlamydia inclusions in the McCoy cells after 48 hr incubation. This effect was dose dependent, could be blocked with anti-estrogens, and also occurred with replicating McCoy cells. Localization studies suggest that this effect on the infectivity of Chlamydia trachomatis is dependent upon initial interactions of estrogens with McCoy cells. Both light microscopy and electron microscopy of the McCoy (fibroblast) cells showed no morphological changes after exposure to the estrogens under the incubation conditions employed in these studies. Estrogens may modify host susceptibility to Chlamydia infections in a manner independent of morphological changes in mammalian cells.

Animals↗
PubMedDate not supplied

The binding of Chlamydia trachomatis and zinc to McCoy cells (mouse fibroblasts).

Zinc was found to have profoundly different effects upon the infection of McCoy cells (mouse fibroblasts) by two strains of Chlamydia trachomatis dependent upon the time and concentration of zinc exposure. Radiolabeled zinc-65 became McCoy cell-associated in a manner independent of incubation temperature, but highly dependent on incubation time and zinc concentration. This effect was maximal after 30 to 60 minutes of incubation. Correspondingly, incubation of a chlamydia inoculant with McCoy cells and supplemental zinc (10(-5) to 10(-4) M) for 1 h was associated with significantly (approximately twofold) more binding of the chlamydia to the McCoy cells compared with control media (8 X 10(-6) M Zn). More prolonged incubation of the chlamydia and McCoy cells with supplemental zinc was associated with significantly fewer chlamydia inclusions. Concentrations of 5 X 10(-4) M zinc or higher were also found to be toxic to the McCoy cells after 48 h of incubation. Brief exposure to supplemental zinc may augment infection of cells by chlamydia: however, more prolonged exposure to the same concentrations of zinc lessens cellular infection by chlamydia.

Cell Line↗