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Biomedical subjects

A Keating

Publications and source records attributed to A Keating.

At least 73 records · Page 4Linked to original sources
PubMed1996

Human hematopoiesis in SCID mice implanted with human adult cancellous bone.

The persistence of hematopoietic cells from human adult cancellous bone fragments implanted subcutaneously into CB-17 scid/scid mice was studied. Recipient mice received either no pretreatment (control group) or pretreatment with 3 Gy total-body irradiation and anti-asialo GM1 sera (ASGM1; pretreated group) before implantation. Pretreated severe combined immunodeficient (SCID) mice implanted with human bone were subsequently given ASGM1 every 7 days for the duration of the experiments. At 12 weeks postimplantation, flow cytometry of cells from pretreated and control animal tissues detected human CD45+ cells in the mouse spleen (mean, 7.8% and 3.4% positive cells, pretreated and control animals, respectively), bone marrow (BM; mean, 16.5% and 4.8% positive cells, respectively), and blood (mean, 5.5% and < 2% positive cells, respectively), and in the implanted human bone (73% and 8.9% positive cells, respectively). At 12 weeks, pretreated mice had human granulocyte-macrophage colony-forming cells (GM-CFC) and burst-forming units-erythrocyte (BFU-E) in the implanted human bone in the murine BM and in some of the spleens. The spleens also had extensive infiltration of human B cells and macrophages. Mean serum levels of human IgG in pretreated animals were 14 micrograms/mL during weeks 6 to 12, compared with trace levels (< 1 microgram/mL) in control mice. Bone from patients with acute myeloblastic leukemia (AML) was also implanted in pretreated SCID mice, and retrieved at 8 weeks for analysis. Comparison of preimplantation and implanted samples showed that the original histology was maintained, and massive infiltration of human CD68+ cells was observed in the mice spleens and BM. Implantation of AML bone in SCID mice facilitates analysis of in situ AML cell interaction with stromal cells in the leukemic state, and therapies against AML can be tested in this system, especially the selective killing of AML cells in the presence of other BM cells. Furthermore, this model requires no exogenous administration of cytokines to maintain human hematopoiesis with both normal or AML bone. Because the structure and function of both normal and diseased human adult bone is maintained, this animal model should facilitate investigation of both normal human hematopoiesis and hematopoietic malignancies.

Acute Disease↗
PubMed1996

Normal and leukemic SCID-repopulating cells (SRC) coexist in the bone marrow and peripheral blood from CML patients in chronic phase, whereas leukemic SRC are detected in blast crisis.

Progress in understanding the abnormal regulation of hematopoiesis in chronic myelogenous leukemia (CML) would be facilitated if neoplastic cells, at all stages of the disease, could be studied in an animal model. In this report, we show that irradiated severe combined immunodeficient (SCID) mice can be transplanted with both normal (Philadelphia chromosome [Ph]-negative) and neoplastic (Ph+) cells from CML patients with either chronic or blast phase disease. Mice transplanted with peripheral blood (PB) or bone marrow (BM) cells from 9 of 12 chronic phase CML patients were well engrafted with human cells including multilineage colony-forming progenitors and CD34+ cells for at least 90 days posttransplantation. Repeated posttransplant injections of cytokines did not enhance the number of engrafted human cells. Interestingly, approximately 70% of the human progenitors found in the engrafted SCID BM were Ph-, suggesting that the growth of primitive normal cells is favored in this in vivo transplant model. A similar number of normal cells were found in mice transplanted with either PB or BM cells, suggesting that elevated numbers of primitive normal cells are present in CML PB. When cells from patients with CML in either myeloid or lymphoid blast crisis were transplanted into SCID mice, the BM of these mice was more rapidly repopulated and to a higher level than that observed with transplants of chronic phase cells. Moreover, all human colony-forming progenitors present in the BM of mice transplanted with blast crisis cells were Ph+, and the majority of cells showed the same morphological features of the blast crisis cells originally transplanted. These experiments provide a starting point for the creation of an animal model of CML and establish the feasibility of using this model for the future characterization of transplantable CML stem cells during disease progression.

Animals↗
PubMed1996

Autologous bone marrow transplantation for acute myeloid leukemia.

Despite progress over the past three decades, most patients with acute myeloid leukemia (AML) treated with conventional chemotherapy alone relapse and die of recurrent leukemia. Treatments used to improve outcome include allogeneic (alloBMT) and autologous bone marrow transplantation (ABMT). Indications for transplantation and the relative merits of alloBMT and ABMT remain unclear. In this review, we evaluate evidence supporting a role of ABMT in AML and compare the results with outcomes after alloBMT. In addition, we discuss areas of controversy including the optimal timing for ABMT, the role of bone marrow purging, the place of peripheral blood stem cell collection, the high dose regimen, and post-transplant immunotherapy to reduce relapse.

Acute Disease↗
PubMed1996

Bead transfection of adherent cells. Gene transfer into adherent mammalian cells using glass beads.

Bead transfection is a simple, rapid, efficient, and cost-effective method of gene transfer into adherent mammalian cells. It involves a brief incubation of the cells with glass beads in a solution containing the DNA to be transferred. We have optimized this technique using COS-7 (an SV40 transformed monkey kidney cell line) and a transient expression assay for chloramphenicol acetyl transferase (CAT). Stable transfection efficiency assessed using the selectable marker gene neomycin phosphotransferase (NEOR) was 27% in COS-7 cells. As this technique delivers high transfection efficiency with little manipulation of the exogenous DNA and does not require the use of any viral sequences, it may be a useful alternative method of gene delivery in the development of gene therapy protocols.

Animals↗
PubMed1996

The role of intensive therapy and autologous blood and marrow transplantation for chemotherapy-sensitive relapsed and primary refractory non-Hodgkin's lymphoma: identification of major prognostic groups.

Patients with intermediate grade non-Hodgkin's lymphoma (NHL) who relapse or fail to achieve a complete remission after anthracycline-containing induction regimens have a poor outcome with conventional-dose salvage treatment. This outcome may be improved with intensive therapy and autologous transplantation (ABMT) but even in patients with proven chemotherapy-sensitive disease, relapse rates of up to 60% are observed. Reliable and powerful prognostic indicators are needed to identify appropriate patients for this expensive procedure and those subjects to whom alternative or additional treatment should be offered. We were interested in testing the hypothesis that tumour burden, and hence remission status immediately prior to transplant, is an important prognostic indicator of survival. We aggressively treated patients with conventional-dose salvage chemotherapy to maximum tumour response, and tested, by multivariate regression analysis, predictors of outcome post-transplant. We studied 81 consecutive patients with intermediate grade and immunoblastic NHL who achieved either a partial (PR) or complete remission (CR) following repetitive cycles of conventional-dose salvage therapy. Intensive therapy consisted of etoposide (60 mg/kg) and intravenous melphalan (160-180 mg/m2) with or without total body irradiation (TBI) followed by infusion of autologous unpurged bone marrow and/or blood cells. The predicted 4-year survival and progression-free survival (PFS) with a median follow-up of 37 months was 58% and 48% (95% confidence interval (CI) 37-55%), respectively. The only factor predictive of outcome was remission status at transplant (P=0.0001). The PFS at 4 years for the CR group was 61% (95% CI 53-75%). In contrast, only 25% (95% CI 11-40%) of patients undergoing autotransplant in PR were progression free at 4 years. We conclude that remission status at transplant after maximum tumour reduction is a powerful prognostic indicator.

Adult↗
PubMed1996

Peripheral blood progenitor cell collections in multiple myeloma: predictors and management of inadequate collections.

Thirty-seven patients with previously treated multiple myeloma (MM) underwent peripheral blood progenitor cell (PBPC) collection following high-dose cyclophosphamide and GM-CSF or sequential IL-3 and GM-CSF. Patients with an inadequate collection were considered for a second or third collection. 25 patients underwent subsequent autotransplant. The only variable predictive of CFU-GM yield was the extent of prior melphalan therapy. All repeat collections were unsuccessful and patients infused with an autograft obtained from multiple sets of collections had a high incidence of delayed engraftment. We conclude that melphalan should be avoided or PBPC collection performed early in the disease course in patients who are potential transplant candidates.

Adult↗
PubMed1996

Intensive therapy and autotransplant for patients with an incomplete response to front-line therapy for lymphoma.

BACKGROUND: Patients with Hodgkin's disease (HD) and intermediate or high-grade non-Hodgkin's lymphoma (NHL) who fail to achieve a complete remission (CR) with standard induction therapy have a poor prognosis with conventional-dose salvage therapy alone. We examined the role of subsequent intensive therapy and autologous bone marrow transplantation (ABMT) in patients who demonstrated a response to conventional-dose therapy. PATIENTS AND METHODS: Sixty-six patients with either HD (n = 30) or NHL (n = 36) underwent intensive therapy with etoposide (60 mg/kg), intravenous melphalan (160-180 mg/m2) followed by infusion of unpurged autologous bone marrow and/or blood cells. All patients had advanced stage or bulky disease at diagnosis and failed to achieve a CR after an anthracycline-containing front-line chemotherapy regimen (NHL) or ABVD or equivalent regimen (HD). Patients who achieved a CR after involved-field radiotherapy were excluded. All patients demonstrated sensitivity to conventional-dose salvage treatment before advancing to intensive therapy and ABMT. RESULTS: The CR, partial response (PR) and overall response rate (RR) following ABMT for HD patients was 48%, 17% and 65%, respectively. At a median follow-up of 35 months, the predicted three-year overall survival (OS) is 51% (95% CI: 44%-60%) and event-free survival (EFS) is 34% (95% CI: 26%-54%). For patients with NHL, the CR, PR and RR were 68%, 9% and 77%, respectively. At a median follow-up of 28 months, the predicted three-year OS is 51% (95% CI: 35%-66%) and EFS is 39% (95% CI: 21%-57%). CONCLUSIONS: Intensive therapy with etoposide and melphalan followed by ABMT results in prolonged survival in selected patients with lymphoma who fail to achieve a complete remission to front-line chemotherapy. Based on our previous studies of outcome to conventional-dose salvage chemotherapy, we estimate that of all patients failing induction therapy, 28% with HD and 15% with NHL will be event-free at three years after ABMT.

Adolescent↗
PubMed1996

Acute leukemia in adults.

Several trends are emerging in the treatment and investigation of acute leukemia in adults; in this review both of these aspects are addressed. Chemotherapy forms the mainstay of treatment for acute myeloblastic leukemia. In the past year, groups reported on the value of dose intensification in patients with acute myeloblastic leukemia under the age of 60 years and on the role of intensive chemotherapy combined with growth factors in the treatment of elderly patients. Similarly, the role of autologous bone marrow transplantation for older patients has been studied. Improvements in the treatment of patients with acute leukemia are likely to come from a recognition and understanding of the biologic attributes of the leukemic cell. Failure to cure leukemia is likely due to failure to eradicate the leukemic clone. Mechanisms of drug resistance acting before the drug reaches its target (proximal resistance) and after the drug interacts with its target (distal resistance) are gaining greater importance in understanding treatment failures. Advances have been made in identifying new mechanisms that are involved in proximal as well as distal drug resistance. Genetic changes both at the cytogenetic and the molecular level identify different FAB subgroups and groups of patients with good and bad prognostic features. Finally, reports are reviewed of two new factors that stimulate the growth of acute myeloblastic leukemia cells (thrombopoietin and Flt3 ligand) and a factor that inhibits the autocrine growth characteristics of acute myeloblastic leukemia cells (interleukin-10). The results of these interface and basic studies offer the hope of identifying groups of patients with different therapeutic needs and suggest ways to develop therapies aimed at the biology of the leukemic cell.

Adult↗
PubMed1996

Chemotherapy versus transplants for acute myelogenous leukemia in second remission.

The best therapy for persons with acute myelogenous leukemia (AML) in 2nd remission is unknown. Bone marrow transplants from an HLA-identical sibling are reported to be better than chemotherapy but this is controversial. The objective of the study was to compare 3-year leukemia-free survival (LFS) in comparable subjects receiving chemotherapy or a transplant. 485 persons with AML in 2nd remission were studied. The chemotherapy cohort included 244 persons treated on trials of the British Medical Research Council, Eastern Cooperative Oncology Group and MD Anderson Hospital. The transplant cohort included 257 persons transplanted worldwide and reported to the international Bone Marrow Transplant Registry (16 were also chemotherapy subjects.) Subjects were selected for comparable age and year of treatment. Preliminary analyses identified two factors correlated with LFS: age < or = or > 30 years and 1st remission duration < or = or > 1 year; subsequent analyses were partitioned accordingly. Three-year probabilities of treatment-related mortality with chemotherapy and transplants were 7% (95% confidence interval, 3-15%) vs 56% (49-63%). Three-year leukemia relapse probabilities were 81% (74-86%) vs 41% (33-49%). Three-year probabilities of LFS were 17% (12-23%) vs 26 (20-32%). Cohort analysis showed significantly higher LFS with transplants vs chemotherapy in persons < or = 30 years and 1st remissions > 1 year (41% (29-53%) vs 17% (7-32%); P = 0.017) and those in > 30 years with 1st remissions < or = 1 year (18% (9-29%) vs 7% (2-16%); P = 0.046). Others had comparable LFS with both treatments. These data indicate better LFS with HLA-identical sibling transplants than chemotherapy in some persons with AML in 2nd remission.

Adolescent↗
PubMed1996

The hematopoietic stem cell in elderly patients with leukemia.

Stem cell reserve and the proliferative capacity of pluripotent hematopoietic progenitors as influenced by age are of intrinsic biologic interest and potential therapeutic importance. The latter is especially true in older persons receiving intensive but not marrow-ablative chemotherapy. Studies of stem cell aging using murine models yield conflicting data. Unfortunately, few studies address the effect of aging on human hematopoietic stem cells, largely because there is no true pluripotent stem cell assay. Some work indicates that the proliferative capacity of human hematopoietic stem cells appears to decrease with age but is unclear whether this is of clinical significance. Our preliminary analysis of more than 500 autotransplant candidates by univariate analysis indicates that higher patient age correlates with reduced committed hematopoietic progenitor cell levels but not with delayed engraftment. In the future, the use of combinations of assays that include phenotypic (CD34+thy1+CD38lo) and functional (long-term culture-initiating cell) characteristics may better identify the effects of aging on candidate stem cells. The development of assays that predict delayed hematopoietic recovery after chemotherapy in older adults may help to tailor therapy for specific patients with the hope of reducing morbidity while retaining efficacy.

ADP-ribosyl Cyclase↗
PubMed1996

HLA-identical sibling bone marrow transplants vs chemotherapy for acute myelogenous leukemia in first remission.

There is controversy whether adults with acute myelogenous leukemia (AML) in first remission are best treated with chemotherapy or an HLA-identical sibling bone marrow transplant. We studied 1097 adults, 16-50 years old, with AML in first remission. Results of transplants from HLA-identical siblings reported to the International Bone Marrow Transplant Registry (IBMTR; n = 901) were compared with results of chemotherapy in comparable persons treated by the German AML Cooperative Group (GAMLCG; n = 196). Preliminary analyses identified subject- and disease-related variables differing between the cohorts and associated with treatment outcome within each cohort. We adjusted for these variables and differences in time-to-treatment in subsequent comparisons of treatment-related mortality, relapse, survival and leukemia-free survival (LFS). Five-year probability of treatment-related mortality was greater for transplants than chemotherapy (43% (95% confidence interval, 37-49%) vs 7% (3-11%); P< 0.0001). Five-year relapse probability was less for transplants than chemotherapy (24% (20-28%) vs 63% (55-71%); P< 0.0001). Five-year probability of survival was similar with transplants and chemotherapy (48% (43-53%) vs 42% (33-51%); P = 0.24). Five-year LFS probability was higher for transplants than chemotherapy (46% (42-50%) vs 35% (28-41%); P= 0.01). These data indicate that bone marrow transplants from HLA-identical siblings result in comparable survival but greater LFS than chemotherapy in adults with AML in first remission.

Adolescent↗
PubMed1996

GM-CSF accelerates neutrophil recovery after autologous hematopoietic stem cell transplantation.

Patients with non-myeloid hematologic malignancies (including Hodgkin's and non-Hodgkin's lymphomas, myeloma and acute lymphoid leukemia) or solid tumors underwent cytoreductive conditioning regimens followed by either autologous bone marrow transplantation (ABMT) (n = 343) or transplantation of peripheral blood stem cells (PBSC) with (n = 44) or without bone marrow (BM) (n = 16). In a randomized double-blind phase III multi-center trial, patients received either granulocyte-macrophage colony-stimulating factor (GM-CSF, 10 micrograms/kg/day) or placebo by daily i.v. infusion beginning 24 h after bone marrow infusion and continuing until the absolute neutrophil count (ANC) had recovered to > or = 1000/mm3, or for a maximum of 30 days. Median time to neutrophil recovery was significantly shorter in the GM-CSF group (18 vs 27 days, P < 0.001), and more GM-CSF patients had neutrophil recovery by day 30 (70 vs 48%). Median duration of hospitalization was significantly shorter in the GM-CSF group (29 vs 32 days, P = 0.02). GM-CSF significantly reduced the median time to neutrophil recovery in patients receiving bone marrow only (19 vs 27 days, P < 0.001) or PBSC with or without bone marrow (14 vs 21 days, P < 0.001). The overall incidence of adverse events was comparable in the two groups, although more patients in the GM-CSF group discontinued treatment due to adverse events (17 vs 9%, P < 0.001). No difference was noted in infection incidence or time to platelet independence. GM-CSF had no negative impact on time to relapse or long-term survival. These data indicate the positive influence of GM-CSF on neutrophil recovery and hospital stay in patients receiving ABMT for a variety of clinical indications.

Adolescent↗
PubMed1995

Biology of bone marrow stroma.

The marrow microenvironment is a complex, three-dimensional structure composed of many cell types and abundant extracellular matrix. Much of the data are derived from analysis of the adherent layer of murine and, especially, human long-term marrow cultures. An essential feature of this in vitro counterpart to the marrow microenvironment is the presence of flat angulated cells functionally defined as marrow stromal cells with the following phenotype: type IV collagen(+), laminin(+), vimentin(+), CD10(+), muscle actin(+), Stro-1(+), and negative for CD45, Mac-1, and HLA-DR. Stromal precursors are Stro-1(+) and CD34(+). Regulation of hematopoietic precursors by the microenvironment occurs by elaboration of regulatory molecules such as hematopoietic cytokines, by cell-cell contact via adhesion molecules such as alpha 4 beta 1 integrin, and by interactions with components of the extracellular matrix as in the case of the glycosaminoglycan hyaluronic acid with cell-associated CD44. Although little about the regulation of stromal cell development itself is known, several studies indicate the transplantability of marrow stromal cells under specific conditions. These developments suggest a potential role of stromal cells in cell therapy. Transfected stromal cells may serve as suitable vehicles for gene delivery to correct single gene disorders in which the product of the target gene does not require stringent regulation as, for example, in the correction of Factor VIII and Factor IX deficiency. Further studies are warranted to investigate marrow stromal cell physiology and regulation to better understand hematopoiesis and to explore the possible use of stroma in therapy.

Bone Marrow Cells↗
PubMed1995

Isolated chloroma: the effect of early antileukemic therapy.

OBJECTIVE: To evaluate the effect of antileukemic chemotherapy administered at diagnosis on the survival of patients with isolated chloroma. DESIGN: Retrospective review of locally identified patients and analysis of cases from the medical literature. PATIENTS: The records of all patients with isolated chloroma identified at three teaching hospitals in Toronto between 1980 and 1994 were reviewed. A MEDLINE search was done to identify all cases of isolated chloroma reported in the English-language medical literature. Patients with a previous known hematologic disorder were excluded. MEASUREMENTS: The effect of therapy on 1) the interval between diagnosis of chloroma and diagnosis of acute myeloid leukemia and 2) survival was determined. RESULTS: 7 local patients and 83 published cases were identified, for a total of 90 evaluable patients. For the entire group, the median time to the diagnosis of acute myeloid leukemia was 9 months, and median survival was 22 months. Chemotherapy was administered to 49 patients (54%) at diagnosis of chloroma. Significantly fewer patients treated with chemotherapy subsequently developed acute myeloid leukemia (41% compared with 71%; P = 0.001). Survival was longer in patients treated with chemotherapy (> 50% alive with a median follow-up of 25 months compared with a median survival of 13 months for those initially untreated; P = 0.001). Multivariate analysis showed that neither local radiotherapy nor surgery had an effect on survival. CONCLUSIONS: Administration of antileukemic chemotherapy at diagnosis of chloroma is associated with a significantly lower probability of developing acute myeloid leukemia and with longer survival.

Acute Disease↗
PubMed1995

Acute leukemia in adults.

The application of recent discoveries in the field of molecular oncology to acute myeloid and lymphoblastic leukemia has provided new insights into the pathogenesis and natural history of these diseases. Cytogenetic abnormalities and the detection of mutations or abnormal expression of certain oncogenes or tumor suppressor genes now provide powerful prognostic information to guide choice of therapy and prediction of response. Randomized trials of intensive postremission chemotherapy have now confirmed improved leukemia-free survival with the use of high-dose cytarabine or allogeneic or autologous bone marrow transplantation. Progress in the treatment of acute myeloid leukemia and acute lymphocytic leukemia in the elderly, where the prevalence of these diseases is likely to increase as our population ages, has been more modest. There is still a need for the evaluation of new treatment strategies in previously untreated patients with acute leukemia, despite the progress that has been reported during the past year.

Acute Disease↗
PubMed1995

Determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry.

Methods for the determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry are described and validated. Aluminium was measured at 167 nm using an argon purged monochromator. Matrix effects in serum and dialysate fluid were overcome by using an yttrium internal standard. Serum was found to have a complicated background in the region of 167 nm: careful selection of the wavelength used for background correction is therefore a pre-requisite for accurate analysis. The method for serum was validated by comparison with electrothermal atomization atomic spectrometry and the limit of agreement determined to be +/- 0.3 mumol/L. Routine performance in a quality assessment scheme has been highly satisfactory for a period of 1 year. The method is ideal for fast and accurate monitoring of patients potentially at risk from aluminium toxicity.

Aluminum↗