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Biomedical subjects

H G Prentice

Publications and source records attributed to H G Prentice.

At least 289 records · Page 16Linked to original sources
PubMed1982

A technique for rapid isolation of bone marrow mononuclear cells using Ficoll-Metrizoate and the IBM 2991 blood cell processor.

Marrow from seven normal donors and patients has been layered onto Ficoll-Metrizoate (FM) under pressure in the IBM 2991 blood cell processor to isolate the mononuclear cell (MNC) population prior to allogeneic transplantation or cryopreservation. This separation method, which takes less than 90 min, is a further development since our previous report detailing the use of the IBM 2991 to produce a concentrated marrow 'buffy coat' for infusion (Gilmore & Prentice, 1981). By adding FM to the system, marrow stem cells are further concentrated in a small volume with removal of unwanted granulocytes and red blood cells. This facilitates in in vitro treatment of marrow with monoclonal antibodies (Granger et al. 1982) or drugs, for either the selective elimination of malignant cells prior to autologous bone marrow transplantation (BMT), or T lymphocytes in an attempt to prevent graft versus host disease (GvHD) in allogeneic BMT. Five of the seven marrows processed by this procedure have thus far been infused into lethally irradiated recipients with engraftment (allogeneic); the other two marrows have been cryopreserved.

Bone Marrow Cells↗
PubMed1982

The effect of deoxycoformycin and deoxyadenosine on deoxyribonucleotide concentrations in leukaemic cells.

Intracellular deoxynucleoside triphosphate pools of normal bone marrow, thymocytes and cells from patients with ALL and AML were measured after 2 h incubation with deoxycoformycin (dCF) 10(-5) M and deoxyadenosine (AdR) 10(-4) M in vitro and after another 30 min incubation in the absence of dCF and AdR ('chase' experiment). Incubation with dCF and AdR resulted in a significant rise of dATP concentrations in all groups (the highest rises occurring in the leukaemic groups particularly in AML and Thy-ALL). The concentrations of the other three deoxyribonucleoside triphosphates fell in all groups. The dATP level fell during the 'chase' period but in Thy-ALL and thymocytes this fall was insignificant and slower than in the other groups. This suggests that not only intracellular build-up of dATP but also the capacity of the cell to degrade dATP is important for in vivo cytotoxicity of dCF treatment. These results help to explain the differences in response to dCF of the different leukaemias.

Bone Marrow↗
PubMed1982

Nucleoside incorporation into DNA and RNA in acute leukaemia: differences between the various leukaemia sub-types.

The incorporation of the labelled deoxyribonucleosides 3H-deoxythymidine (3H-TdR), H3-deoxycytidine (3H-CdR), 3H-deoxyadenosine (3H-AdR), 3H-deoxyguanosine (3G-GdR), 3H-deoxyuridine (3H-UdR) and of labelled uridine (3H-UR) into DNA and RNA was studied in bone marrow (BM) and peripheral blood (PB) cells from 10 normal donors and 11 patients with acute myeloblastic leukaemia, 13 with acute non-T non-B common ALL (c-ALL) and seven with thymic acute lymphoblastic leukaemia. 3H-TdR incorporation was highest into the DNA of normal BM cells, 3H-CdR into DNA in Thy-All and 3H-UdR into DNA of c-ALL cells. Purine deoxynucleoside (3H-AdR and 3H-GdR) incorporation was highest in AML cells and they were incorporated mainly into RNA indicating that before utilization they are partially degraded from the deoxyribose to the corresponding ribose form. In all but three leukaemia samples, the 3H-UdR/3H-TdR incorporation ratio was above the range found in normal bone marrow, suggesting the leukaemic cells are more dependent than a normal mixed marrow cell population on the de novo pathway of thymidylate synthesis. The incorporation of nucleosides by peripheral blood cells was usually much lower than by the corresponding bone marrow cells, irrespective of blast percentage.

Blood Cells↗
PubMed1982

OKT3 incubation of donor marrow for prophylaxis of acute graft-vs.-host disease (GvHD) in allogeneic bone marrow transplantation.

Following allogeneic (matched or minor mismatched) bone marrow transplantation with marrow incubated with OKT3, 17 patients have been observed for at least 60 days for the development of acute graft-vs.-host disease. One milligram of the monoclonal (murine) antibody OKT3 was incubated with the donor marrow for one hr at room temperature prior to infusion. It was anticipated that coated/opsonized immune competent T lymphocytes would subsequently be phagocytosed by the recipient reticulo-endothelial system. Three of 17 patients developed Grade II or greater acute graft-vs.-host disease. In two, this proved fatal when complicated by cytomegalovirus infection. Eleven patients showed no evidence of acute graft-vs.-host disease and three had transient limited skin rashes (Grade I graft-vs.-host disease). Opsonization of T lymphocytes has reduced the incidence of severe acute graft-vs.-host disease in this unit from 79% (historical group) to 18% when added to prophylactic methotrexate given according to the Seattle protocol.

Acute Disease↗
PubMed1982

Immunological analysis of the skin in graft versus host disease.

Immunohistochemical analysis was performed on skin biopsies from patients suffering from graft versus host disease (GVHD) following bone marrow transplantation for aplastic anaemia and leukaemia. Lymphoid cells infiltrating the skin were exclusively T cells with the OKT8+ phenotype and these are probably cytotoxic T cells. Langerhans cells were reduced in number in all specimens and a variable number of HLA-DR positive macrophages were seen in the dermis. In several cases HLA-DR antigens were expressed on keratinocytes. These results show consistent features which may help discriminate rashes in the skin in the post-transplant period.

Adolescent↗
PubMed1981

Therapeutic selectivity of and predication of response to 2'-deoxycoformycin in acute leukaemia.

Seventeen patients with acute leukaemia refractory to conventional chemotherapeutic agents were treated with the adenosine deaminase inhibitor, 2'-deoxycoformycin (dCF). Of the twelve patients with acute lymphoblastic leukaemia of the thymic phenotype (Thy-ALL), seven went into complete remission after one or two courses of therapy. Two other (Thy-ALL) patients showed good partial response, and three were resistant to dCF. The five patients with acute leukaemia of other phenotypes had progression of disease despite treatment with dCF. Response to dCF can be predicted from the pattern of change in cellular nucleotide levels in blood and/or bone marrow blasts which have been treated in vitro with dCF and deoxyadenosine. The main adverse effects of dCF therapy were renal and liver dysfunction, conjunctivitis, and haemolysis.

Acute Disease↗
PubMed1981

A phase I and II study of m-AMSA in acute leukaemia.

Thirty-two patients with relapsed or resistant acute leukaemia were treated with m-AMSA at doses ranging from 50-150 mg/m2 daily for 5 days. Complete remission was achieved in three of 18 patients with acute myeloblastic leukaemia, two of nine patients with acute lymphoblastic leukaemia, and none of five patients with blastic crisis of chronic myeloid leukaemia. The complete remissions all occurred at doses of 100 mg/m2 per day or above. Haematological toxicity occurred in all patients and was dose-related. Nausea and vomiting were mild and easily controlled. Alopecia was uncommon at the lower doses but occurred in all patients receiving the higher doses. Stomatitis was noted in only 8% of courses at 50 mg/m2 but was seen in 50% of courses at 150 mg/m2. Mild and transient elevations of liver enzymes were common. m-AMSA is an active drug in acute leukaemia, with acceptable toxicity. Its place in combination chemotherapy is now being explored.

Adolescent↗
PubMed1981

Immunological characterization of hemopoietic cells in the common marmoset, rhesus monkey, and man. In search of a model for human marrow transplantation.

Bone marrow, lymphoid, and peripheral blood cells from the common marmoset and rhesus monkey have been tested with a panel of heterologous and monoclonal antibodies, and their reactivity pattern has been compared with that of blood and bone marrow cells from human donors. Conventional antibodies reveal extensive cross-reactivity within the B cell, T cell, and granulocytic systems in all three species, however, some important differences have been exposed. Only the monoclonal antibodies to HLA-A,B,C and Ia-like antigens react with marmoset cells, and we have exploited this finding to show that the vast majority of colony-forming units (CFU-c) in the marmoset bone marrow (as in man) are Ia positive. The use of the common marmoset as a suitable model for human bone marrow transplantation is discussed in the light of these findings.

Animals↗
PubMed1981

DNA synthesis in thymic-acute lymphoblastic leukaemia.

Deoxyribonucleoside triphosphate (dNTP) concentrations were measured in bone marrow and peripheral blood leucocytes from seven patients with acute Thy-lymphoblastic leukaemia (Thy-ALL), 12 patients with acute myeloblastic leukaemia and 15 patients with acute non-T, non-B lymphoblastic leukaemia (c-ALL), and in thymocytes from patients with myasthenia gravis. Labelled thymidine and deoxycytidine incorporation into DNA was also studied. In Thy-ALL, dNTP concentrations were markedly increased compared with those in the other acute leukaemias. The dNTP concentrations in thymocytes were, however, similar to those in Thy-ALL. 3H-nucleoside incorporation studies showed a marked difference in labelled deoxycytidine incorporation and particularly in the deoxycytidine/thymidine DNA labelling ratio between Thy-ALL and the other cell types. We conclude that the pathways of DNA synthesis in Thy-ALL blasts are different from those in the cells from acute acute leukaemias and some but not all these differences may correspond to differences between normal cortical thymocytes and bone marrow cells.

Bone Marrow↗
PubMed1981

Immunofluorescent and biochemical studies of terminal deoxynucleotidyl transferase in treated acute leukaemia.

Indirect Immunofluorescence (IF) for terminal deoxynucleotidyl transferase (TdT) was used in conjunction with the biochemical assay of TdT enzymatic activity to study human leukaemias before and during therapy. In addition, non-leukaemic marrows were analysed to compare the enzyme expression on normal cells. An excellent correlation was observed between the IF and biochemical methods when specimens contained greater than 5% TdT+ cells (by IF); below this level the biochemical assay was less reliable, while the sensitive IF test could detect isolated TdT+ cells among greater than 10 000 TdT negative cells. The IF method also had the advantage of allowing further immunological characterization of TdT+ cells, by simultaneous labelling of membrane antigens with appropriate antisera. TdT+ cells expressing Ia-like antigens (but lacking other antigens associated with B- and T- lymphoid differentiation) were frequently found in low numbers in remission marrows from acute lymphoblastic leukaemia (ALL) patients. However, similar cells were also observed in remission acute myeloid leukaemia, as well as in non-leukaemic regenerating marrows, and marrow from normal donors. The presence of these normal TdT+ precursor cells therefore precluded the use of either IF or biochemical TdT tests for estimating the degree of residual disease or predicting early relapse in patients with non-T, non-B ALL. In contrast, the detection of TdT+ cells with T lymphoid antigens (HuTLA+) but lacking Ia antigens, in thymic (T-cell)-ALL, but not in normal marrow, allowed the use of this combination of markers to detect minimal residual disease in T-ALL.

Acute Disease↗
PubMed1981

Studies on the biochemical sequelae of therapy in Thy-acute lymphoblastic leukaemia with the adenosine deaminase inhibitor 2' deoxycoformycin.

In four patients with Thy-acute lymphoblastic leukaemia changes in blast cell deoxynucleoside triphosphate concentrations and, in three, changes in blast cell S-adenosyl homocysteine hydrolase activity were measured during treatment with 2' deoxycoformycin, a potent inhibitor of adenosine deaminase. These studies were aimed at identifying the molecular basis of cell killing by this drug. In three patients an increase in blast deoxyadenosine triphosphate (dATP) concentration occurred which was found to be temporally related to cell killing and was accompanied by decreased concentrations of the other three deoxyribonucleoside triphosphates. In the one patient with Thy-ALL who responded poorly to treatment, the increase in dATP concentration was delayed and was not accompanied by a fall in the concentrations of the other deoxyribonucleoside triphosphates. Progressive inactivation of blast cell S-adenosyl homocysteine hydrolase was found to occur in the three patients tested but was maximal only after a substantial reduction of peripheral blast cell count. These results show that 2' deoxycoformycin has a potent cytoreductive effect in Thy-ALL and suggest that the molecular basis of this toxicity is related both to the intracellular accumulation of dATP with inhibition of ribonucleotide reductase. Inactivation of S-adenosyl homocysteine hydrolase may be of importance as an additional mechanism.

Adenosine Deaminase↗
PubMed1981

Reactivity of monoclonal antibodies with human myeloid precursor cells.

Five monoclonal antibodies have been tested for their ability to bind to myeloid precursor cells in normal human bone marrow. Indirect immunofluorescence and the fluorescence activated cell sorter was used to separate cells according to their reactivity for trial culture in vitro in order to grow granulocyte-macrophage colony forming cells (CFUc). Two antibodies (OKT3 and OKT11) which react strongly with bone marrow T lymphocytes were found to be unreactive with CFUc. YD1/23 reacts very strongly with both T and B lymphocytes but is only weakly reactive with CFUc. In contrast, OKT10 and YE2/36 did react with CFUc. The consequences of these findings and the potential clinical use of these antibodies in bone marrow transplantation are discussed.

Adult↗
PubMed1981

Terminal transferase expression in relapsed acute myeloid leukaemia.

In three cases of acute myeloid leukaemia marked increases in expression of the nuclear enzyme, terminal deoxynucleotidyl transferase (TdT), were observed during disease relapse. The first case was heterogeneous at diagnosis, consisting of subpopulations of large TdT- myeloblasts and small TDT+ blasts; however, at relapse there was complete replacement by TdT+ lymphoblasts. The other cases at diagnosis were both typical acute myeloid leukaemia, TdT-; at relapse, one showed a mixture of TdT- myeloblasts and TdT+ lymphoblasts, while in the other, TdT was demonstrated on a subpopulation of myeloblasts. No chromosomal abnormalities were found. It is suggested that in the first two cases these phenomena may have been due to leukaemic involvement of a pluripotential stem cell, or that sub-clones with different properties may have coexisted. In the third case at relapse, TdT was expressed aberrantly by malignant myeloid cells.

Aged↗