PubMed Health⌕ Search

Biomedical subjects

D D Ma

Publications and source records attributed to D D Ma.

At least 37 records · Page 2Linked to original sources
PubMed1994

Specificity and sensitivity of immunocytochemistry for detecting P-glycoprotein in haematological malignancies.

AIMS: To determine the optimal working conditions of the alkaline phosphatase-antialkaline phosphatase (APAAP) method to establish a specific and sensitive assay for the detection of low numbers of MDR positive cells in patients with hematological malignancies. METHODS: Three monoclonal antibodies (C-219, JSB-1, MRK-16) were used for the detection of P-glycoprotein (P-gp) in cell lines and in samples from 43 patients with haematological malignancies. The results of the APAAP method were compared with western blotting for specificity and sensitivity. RESULTS: Excellent correlation was obtained between optimised APAAP and western blotting, except in the case of multiple myeloma. JSB-1 seemed to be the more useful monoclonal antibody for the APAAP which was more sensitive than western blotting in its ability to detect single P-gp positive cells. CONCLUSIONS: Methods for P-gp detection, as defined by multidrug resistant (MDR) cell lines, are not necessarily optimal and specific for clinical samples and may lead to higher false positive and negative results, according to the conditions and the monoclonal antibodies used.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

A Ph+ acute myeloid leukaemia expressing both CML-type and ALL-type BCR/ABL mRNA transcripts.

This report describes a patient presenting with acute myeloid leukaemia (AML-FAB classification M2). Phenotypic markers were positive for cells of the myeloid lineage, but negative for monocyte/macrophage, megakaryocyte, and T-cell lineages. The occasional blast was positive for CALLA. All blasts carried the Philadelphia chromosome (Ph+), with 20% also harbouring a monosomy 7 (a cytogenetic marker for AML). Reverse transcriptase polymerase chain reaction (RT-PCR) analysis revealed the presence of two BCR/Abl mRNA transcripts; b2a2, the CML-type and E1a2, the ALL-type. Immunoglobulin (Ig) gene analysis demonstrated the presence of a small population of cells containing rearranged Ig genes. After a short remission, the patient relapsed. At relapse the leukaemia had undergone a major phenotypic switch from AML to ALL, with blasts bearing B-cell markers. Ig gene analysis confirmed a monoclonal population of B-cells. The Ph+ persisted, but the monosomy 7 had disappeared. The same two BCR/Abl mRNA transcripts were found at relapse as at presentation. To our knowledge, this is the first report of an AML simultaneously expressing BCR/Abl transcripts from both the minor and major BCR. The possible mechanisms of this dual expression are discussed.

Base Sequence↗
PubMed1993

Combined interferon alfa-2a and cytosine arabinoside as first-line treatment for chronic myeloid leukemia.

Thirty patients with chronic myeloid leukemia in chronic phase and less than 1 year from diagnosis were treated with a combination of interferon alfa-2a (IFN) 9 million units daily continuously and intermittent low-dose cytosine arabinoside (Ara-C) 20 mg/m2 daily for 21 days every 42 days. The leukemia was controlled initially with hydroxyurea prior to commencing IFN and Ara-C. The treatment was continued for at least 12 months after which time nonresponders were withdrawn from the trial and responders continued on IFN alone. The median duration of follow-up is 14 months (range 10-53 months). Hematological response was assessed by clinical and laboratory parameters and cytogenetic response was assessed by regular bone marrow chromosome analysis. A complete hematological response occurred in 28/30 patients (93%). A complete cytogenetic response (no detectable Philadelphia chromosome-positive metaphases) was present on at least one occasion in 9/30 (30%), a partial cytogenetic response (between 1 and 34% Philadelphia chromosome-positive metaphases) in 7/30 (23%) and a minor response in 4/30 (13%), giving an overall cytogenetic response rate of 67%. Significant side effects included mucositis, nausea, cytopenia and depression. Side effects could be managed by dose reduction or temporary cessation and were tolerable in most patients, but in 1 patient this led to withdrawal from the trial due to severe depression. Two patients have transformed, 1 to acute lymphoblastic leukemia and 1 to accelerated phase. Two patients have died after exiting the study, both from complications of allogeneic bone marrow transplantation. In conclusion, these results are superior to the results using IFN alone and indicate the need for a randomized study.

Adolescent↗
PubMed1992

Assessment of an EIA for measuring human serum erythropoietin as compared with RIA and an in-vitro bioassay.

A recently developed enzyme-linked immunosorbent assay (EIAZ, ELISA) using two murine monoclonal anti-erythropoietin antibodies was compared with a radioimmunoassay (RIA) and a commercial in-vitro bioassay, EPOS, for measuring serum erythropoietin (Epo) in humans. Specificity and validity for Epo-EIA and the other two assays were examined. The serum Epo in normal subjects was 18 +/- 12 mU/ml (mean +/- SD, n = 80) for EIA compared with 22.5 +/- 18.5 mU/ml (n = 20) for RIA and 136 +/- 132 mU/ml (n = 14) for the bioassay. The serum Epo concentrations in normals and patients were highly comparable between EIA and RIA for Epo (P less than 0.01, r = 0.95). Epo concentrations by the EIA for normal female and male subjects were 20.5 +/- 13 and 16.5 +/- 10 mU/ml, respectively. Epo levels in patients with secondary polycythaemia or autoimmune haemolytic anaemia were significantly higher than normal subjects by the three methods. Epo levels in patients with chronic renal failure were within the normal range. By the EPOS bioassay, the Epo concentrations of normals and patients with renal failure were significantly higher than expected (136 +/- 132 and 447 +/- 273, respectively). Due to its inherent design, the EPOS bioassay possibly measures bone marrow proliferative activity in response to other serum growth regulators besides erythropoietin and was found to be unsuitable for clinical assessment of Epo. We concluded that the new EIA and RIA were similarly sensitive, reliable and accurate for measurement of serum Epo. The EIA method has the advantage of being less time consuming, more convenient and avoids the use of a radioisotope.

Adolescent↗
PubMed1992

A method for enriching myeloid (CFU-GM) and erythroid (BFU-E) progenitor cells from human cord blood by accessory cell depletion.

Human cord blood provides a convenient alternative to bone marrow as a rich source of hemopoietic progenitor cells. This study reports a simple means for enriching a cord blood progenitor cell population by accessory cell depletion. Two methods of monocyte depletion were tested. A Cytodex 3 microcarrier system using collagen coated dextran beads was compared to the more commonly used method of plastic plate adhesion. The method of plastic plate adhesion gave a significantly higher cell recovery. T cell depletion using a recently characterized rat monoclonal antibody which fixes human complement was also investigated. A combined method of monocyte depletion by plate adhesion and T cell depletion resulted in the removal of > 96% of monocytes and > 98% of T cells. This led to a significant enrichment of myeloid (CFU-GM) and erythroid (BFU-E) colony growth. Such enriched progenitor cell populations provide a useful starting population for any study on hemopoiesis.

Cell Separation↗
PubMed1990

Sweet's syndrome associated with sideroblastic anaemia.

Previous reports have noted an association between Sweet's syndrome (acute febrile neutrophilic dermatosis) and leukaemia, and less commonly other haematological abnormalities. We report a previously unrecognised association between Sweet's syndrome (SS) and sideroblastic anaemia (myelodysplastic syndrome--refractory anaemia with ring sideroblasts). Both patients were males and one had prominent extracutaneous features of SS. Bone marrow cytogenetic studies were normal in this latter patient and neither patient showed progression to leukaemia.

Aged↗
PubMed1990

A study of serum free medium culture on the cloning efficiency of human bone marrow myeloid and erythroid progenitors.

Thirteen different combinations of serum-free media were tested to assess their suitability to replace serum containing medium for in vitro culture of human hemopoietic progenitors (CFU-GM and BFU-E). Bone marrow samples from patients with and without hematological diseases were tested. All tested media supported the growth of CFU-GM and BFU-E colonies, however our results have shown that the cloning efficiency of all commercially available serum-free media tested was lower (mean 18% and 12% of controls for CFU-GM and BFU-E respectively) and the colony size was smaller than those in serum-containing medium. In the serum-free cultures, there was no linear relationship between the colony numbers and cell concentration plated. Depletion of T-lymphocytes and monocytes did not improve the cloning efficiency of the serum-free medium culture. Furthermore, the addition of high concentration of insulin, transferrin and other supplements to the serum-free media did not improve the cloning efficiency. These results have indicated that the currently available commercial serum-free media do not provide optimal requirements for hemopoietic progenitor cell cultures and that other factors contained in serum are essential for their optimal growth.

Blood Physiological Phenomena↗
PubMed1987

Detection of a multidrug resistant phenotype in acute non-lymphoblastic leukaemia.

Most adult patients with acute non-lymphoblastic leukaemia (ANLL) relapse with drug resistance. Overexpression of a plasma membrane protein, P-glycoprotein, correlates with multidrug resistance in human and animal cell lines. We have detected a multidrug resistance phenotype in two patients with drug resistant ANLL by an immunocytochemical assay using a monoclonal antibody to P-glycoprotein. Sequential analysis of peripheral blood samples from both patients showed a progressive increase in both the intensity of staining and the proportion of leukaemic cells that bound antibody as the disease progressed. The assay is simple, and may have prognostic and therapeutic implications.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

Donor marrow progenitors (CFU-Mix, BFU-E and CFU-GM) and haemopoietic engraftment following HLA matched sibling bone marrow transplantation.

Bone marrow multipotent (CFU-Mix) and unipotent (CFU-GM and BFU-E) progenitor cells in the donor marrow inoculums were measured in 24 histocompatible sibling bone marrow transplants. The number of donor marrow nucleated cells, CFU-Mix, CFU-GM and BFU-E given per kilogram (kg) of recipient's body weight were 2.4 +/- 0.6 X 10(8), 3.6 +/- 4.2 X 10(3), 4.9 +/- 3.3 X 10(-4) and 4.3 +/- 4.1 X 10(4) respectively (mean +/- S.D.). Fast engraftment patients, as assessed by rise in peripheral blood neutrophils (greater than or equal to 0.5 and greater than or equal to 1.0 X 10(9)/l) and platelets (greater than 20 and greater than 50 X 10(9)/l), received a significantly greater amount of CFU-Mix/kg (greater than 3 X 10(3)/kg, p less than 0.025) and CFU-GM/kg (greater than 3 X 10(4)/kg, p less than 0.05 except for plat greater than or equal to 20 X 10(9)/l) than the slow recovery patients. Significant correlations were found between the donor CFU-Mix/kg infused and neutrophil recovery to 1 X 10(9)/l and platelet to 50 X 10(9)/l (Spearman's rank correlation coefficient r = 0.38, p = 0.04 and r = 0.58, p = 0.003, respectively). The amount of donor CFU-GM/kg given also correlated significantly to neutrophil (1 X 10(9)/l) and platelet (50 X 10(9)/l) recovery, (r = 0.33 and r = 0.37, respectively, p less than or equal to 0.05). There was no association between BFU-E, and marrow nucleated cells infused per kg and haemopoietic recovery. A number of clinical parameters were also examined to determine other factors that may influence the rate of engraftment. Acute graft vs host disease (greater than or equal to grade II) and methotrexate therapy post-transplant delayed the platelet regeneration. The results of the present report indicate that in vitro measurement of donor CFU-Mix and CFU-GM progenitors infused, correlate with the speed of granulocyte and platelet recovery in clinical allogeneic bone marrow transplants.

Blood Grouping and Crossmatching↗
PubMed1987

Chromosomal analysis of bone marrow stromal fibroblasts in allogeneic HLA compatible sibling bone marrow transplantations.

Karyotyping was performed on bone marrow stromal fibroblasts and marrow haemopoietic cells on six patients who received bone marrow transplants from siblings of the opposite sex. Three patients with severe aplastic anaemia received unmanipulated donor bone marrow cells. Three other patients with leukaemia and conditioned with high dose chemotherapy (+ total body irradiation in two patients) received T-cell depleted marrow mononuclear cells. Marrow chromosomal analysis was performed on samples obtained between 6 weeks and 1 yr post-transplant. All marrow fibroblasts studied were of recipient origin, whereas all haemopoietic cells were of donor origin. These results demonstrate that in allogeneic sibling marrow transplantation, recipient bone marrow stromal cells regenerate and repopulate the bone marrow and this is not influenced by the conditioning regimen used, the type and dose of marrow cells given and the pre-existing disease.

Anemia, Aplastic↗
PubMed1987

Haemopoietic reconstitution after allogeneic bone marrow transplantation in man: recovery of haemopoietic progenitors (CFU-Mix, BFU-E and CFU-GM).

Haemopoietic reconstitution was evaluated in 44 patients given HLA compatible sibling bone marrow transplants. The mean peripheral blood haemoglobin, neutrophil and platelet counts were markedly reduced early post-graft but returned to normal by 26 weeks post transplant. Bone marrow multipotent (CFU-Mix), erythroid (BFU-E) and myeloid (CFU-GM) progenitor cell reconstitution were also assessed at regular intervals up to 2 years post-graft. The mean value of CFU-GM increased gradually and attained a normal value by 52 weeks. The BFU-E value did not reach a normal value until after 52 weeks post-graft. However, CFU-Mix growth appeared to be impaired even up to 2 years post-transplant. The occurrence of graft versus host disease at 3 months post-transplant was associated with significantly lower mean numbers of platelets, marrow CFU-GM, BFU-E and CFU-Mix. Post-transplant patients who were on methotrexate therapy were also shown to have lower marrow CFU-GM and neutrophil values compared to those patients who received cyclosporin post-transplant. This study demonstrated that although peripheral blood counts were normal after 26 weeks post-graft, marrow stem cell reserve in these patients was reduced. This might in part explain the documented increase in risk of severe infections or thrombocytopenia in some of these patients, particularly during viral infection, graft-versus-host disease or immunosuppressive treatment.

Adult↗
PubMed1987

Mitozantrone-induced toxicity and DNA strand breaks in leukaemic cells.

By applying the fluorometric analysis of DNA unwinding (FADU) the in vitro effect of mitozantrone on DNA strand breaks was studied in seven different human leukaemic/lymphoma cell lines and in fresh leukaemic samples from seven patients with acute myeloid leukaemia refractory to conventional treatment. Pulse exposure to mitozantrone for 30 min invariably caused strand breaks. In the cell lines JM 1, KM3 and RPM I 8420 DNA strand breakage was progressive upon further incubation in drug free medium. These cell lines were killed by pulse exposure to mitozantrone. In the cell lines Molt 4, Daudi, Raji and HL-60, the DNA strand breaks induced by mitozantone were only moderate and these cell lines were also resistant to killing by mitozantrone in vitro. The leukaemic cells of one of the seven patients behaved also like the cell lines that were sensitive and a complete remission was achieved in this patient using mitozantrone as single agent therapy. The other patients with a pattern similar to the resistant cell lines proved to be clinically refractory. Thus mitozantrone induces rapidly progressive DNA strand breaks as early as 30 min in leukaemic cells that are sensitive. The measurement of DNA strand breaks by the fluorometric analysis of DNA unwinding is a rapid method which might predict response to drugs whose major effect is on the induction of strand breaks.

Cell Line↗
PubMed1986

Purine degradative enzymes and immunological phenotypes in chronic B-lymphocytic leukaemia: indications that leukaemic immunocytoma is a separate entity.

Investigations of the purine degradative enzymes adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and ecto-5'-nucleotidase (5'NT) have been shown to be of value in defining subsets of lymphoid malignancies. We have studied the activities of these enzymes in the circulating malignant cells of 35 patients with chronic B lymphocytic leukaemia and have correlated the biochemical data with immunological phenotypes. Classification of the cases into those without evidence of secretory activity ('true' CLL, 14 patients) and those with cytoplasmic immunoglobulin (CIg) ('immunocytoma'; 21 patients) revealed that immunocytomas are phenotypically and biochemically associated with more mature features. Malignant cells without CIg were characterized by low activities of ADA, PNP and 5'NT. In malignant cells with evidence of secretory activity (immunocytoma), low activity of ADA was also observed, but the activities of PNP and 5'NT were relatively high and approached the range of normal B lymphocytes. The differences in PNP (P less than 0.05) and in 5'NT (P less than 0.01) between these two groups were significant. Phenotypically the cells without CIg were predominantly associated with IgM (+k light chains) as surface membrane immunoglobulin (SmIg) whereas expression of IgG was more often observed in the leukaemic cells with CIg. No correlation between enzyme patterns and the stage of the disease was apparent. Thus both biochemical and immunological criteria show that cases of CLL vary within a range of maturity and that those with CIg might be more mature in the B cell axis. The present study emphasizes the value of purine enzyme studies in defining subsets of B cell neoplasia.

5'-Nucleotidase↗
PubMed1986

Histiocytic necrotizing lymphadenitis (Kikuchi's disease).

We report a typical case of histiocytic necrotizing lymphadenitis. To our knowledge, this is the first reported case in Australasia. Histiocytic necrotizing lymphadenitis (Kikuchi's disease) is a distinct disorder originally reported in Japan. It commonly affects young females and involves mainly cervical lymph nodes. The condition is benign. The etiology of histiocytic necrotizing lymphadenitis and its distinction from other causes of benign and malignant lymphadenopathies are discussed. The clinical importance of this disorder is that, histopathologically, it could be misdiagnosed as malignant lymphoma and therefore patients may receive incorrect treatment.

Adult↗
PubMed1986

Studies of hemopoietic stromal fibroblastic colonies in patients undergoing bone marrow transplantation.

We report here the results of serial bone marrow fibroblast cultures from recipients of histocompatible allogeneic bone marrow transplants (37 patients with acute leukemia, and seven with severe aplastic anemia). The mean value of marrow CFU-F growth for recipients at day 21 after transplant was significantly lower than that for normals and for patients before transplant. There were no obvious differences in the morphologic, ultrastructural, and cytochemical characteristics of the CFU-F between the normals and the patients who received transplants. The number of stromal CFU-F cells in S phase was increased during the early period after transplantation, as demonstrated by a significant reduction of CFU-F growth after short exposure to hydroxyurea. However, the return to normal was rapid, within six weeks. The presence of graft-vs-host disease (greater than or equal to grade II) and the choice of immunosuppressive drug, i.e., methotrexate or cyclosporine, did not affect the CFU-F recovery. The findings in the present study show that the marrow stromal compartment is compromised after marrow transplantation, but its regeneration is rapid. No in vitro CFU-F growth was obtained from peripheral blood of donors and patients, either before or after bone marrow transplant.

Bone Marrow Cells↗