Transplantation of patients with high risk acute myeloid leukemia in first remission with autologous marrow cultured in interleukin-2 followed by interleukin-2 administration

Relapse rates in patients after autologous bone marrow transplantation (BMT) for acute myeloid leukemia (AML) continue to be high despite the use of aggressive conditioning regimens. Based on studies in the murine system a clinical protocol was developed that utilizes immunotherapy to obtain a graft-versus-leukemia (GVL) effect both pre-BMT (to purge leukemic cells from the autograft) and post-BMT (to eradicate residual leukemia in the patient). As part of a phase I study, 10 consecutive patients (median age 41 years, range 15-60 years) with 'high risk' AML (i.e. any of the following: FAB M5, WBC of > or = 50 x 10(9)/l at diagnosis or 'unfavorable' cytogenetic abnormalities) were transplanted at a median of 32 days (range 13-128 days) after achieving first remission. Marrow cells to be autografted were first cultured for 8 days at 37 degrees C in standard long-term culture medium (containing 12.5% horse serum, 12.5% fetal calf serum and 10(-6) M hydrocortisone) to which 1000 U/ml of interleukin-2 (IL-2) was also added. During this time patients received busulfan 4 mg/kg for 4 days and cyclophosphamide 60 mg/kg for 2 days). On the day of transplantation (day 0), the cultured marrow cells were collected from the flasks and infused over 1 h. Between days 0 and 7 patients were given escalating doses of subcutaneous IL-2 (2, 4 and 6 x 10(5) U/m2/day, 3-4 patients/dose level). Side-effects attributable to IL-2 were generally mild, dose-dependent and consisted of fever and malaise.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of committed and primitive blood progenitor mobilization after chemotherapy and growth factor treatment and their use in autotransplants

Peripheral blood cells (PBCs) collected by leukapheresis after progenitor mobilization with chemotherapy and growth factors have been used successfully to replace marrow autografts in protocols requiring stem-cell support. Moreover, such transplants are often associated with more rapid recovery of blood cell counts than is routinely achieved with bone marrow. While conditions that mobilize colony-forming cells (CFCs) into the circulation are becoming increasingly well characterized, little information is available as to how these or other mobilizing treatments may influence the release of more primitive cells into the peripheral blood. To quantitate the peripheral blood content of such cells, we used the long-term culture-initiating cell (LTC-IC) assay, which detects a cell type that is able to produce progeny CFCs after a minimum of 5 weeks in cultures containing marrow fibroblasts. In this report, we present the findings on 21 patients who were transplanted over a 7-year period at our institution with PBCs alone. PBCs were collected in steady-state (n = 6) or during the recovery phase after high-dose cyclophosphamide (Cy; n = 15, nine with and six without additional growth factor administration). PBCs collected from another 11 patients given granulocyte colony-stimulating factor (G-CSF) were transplanted together with autologous marrow. Time-course studies of nine patients after Cy +/- granulocyte-macrophage CSF (GM-CSF) showed that CD34+ cells, CFCs, and LTC-ICs fell from normal to undetectable levels after Cy, and increased at the time of white blood cell (WBC) recovery: LTC-ICs to a mean of sixfold and CFCs to a mean of 26-fold higher than normal. The mean number of CD34+ cells, CFCs, and LTC-ICs present in the PBC harvest was twofold to 10-fold higher after mobilization than in steady-state collections; however, more than 2-log interpatient variability was observed. After PBC transplantation, the median time to a WBC count more than 10(9)/L was 12 days; polymorphonuclear leukocyte (PMN) count more than 0.5 x 10(9)/L, 15 days; and platelet count more than 20 x 10(9)/L, 17 days, although patients who received fewer than 1.5 x 10(5) CFCs/kg had a more than 50% chance of delayed count recovery (> 28 days). Patients who received Cy + GM-CSF-stimulated PBCs had more rapid and consistent platelet recoveries as compared with other groups receiving Cy mobilized or steady-state PBCs alone, and a rapid WBC recovery after Cy predicted a rapid WBC recovery after transplantation.(ABSTRACT TRUNCATED AT 400 WORDS)

Opinion polling and decision making: a critical appraisal of quality of life assessment

The relationship between quality of life (QOL) assessments and decision making, in relation to the delivery of health services, is subjected to critical appraisal. Three levels of decision making in the health care system are taken into account in the analysis. Criticisms of opinion polling provide the basis for the appraisal. Examples of criticisms considered are: Might the use of QOL information be manipulative? Could the interviews or questionnaires used to obtain QOL data influence personal opinions? Are the methods used sometimes defective and/or superficial? Will QOL information always be used in decision making in ways that are ascertainable and justifiable? It is concluded that the time has come for the main focus of critical appraisal in QOL research to shift, from an emphasis on evaluation of the quality of methods used for assessments of QOL, toward an emphasis on the practical usefulness of QOL data.

Cytokines acting early in human haematopoiesis

In long-term cultures (LTC) of human haematopoietic cells, primitive progenitors termed LTC-initiating cells can be maintained for several months and will differentiate to produce clonogenic cells and mature granulocytes and macrophages when provided with a supportive feeder layer of adherent mesenchymal cells. Primitive haematopoietic cells become associated with this feeder layer and their proliferative status and differentiation are regulated by their interaction with these feeder cells and the growth factors they produce. Both positive and negative regulators are generated in LTC and the balance between these diverse factors is readily manipulated by both direct and indirect mechanisms which appear to operate in a localized fashion. These features parallel those believed to characterize the mechanisms that regulate haematopoiesis in the bone marrow microenvironment in vivo and suggest that further analysis of the LTC system will be useful in delineating the full mystery of this process.

Intensive therapy with cyclophosphamide, carmustine, etoposide +/- cisplatin, and autologous bone marrow transplantation for Hodgkin's disease in first relapse after combination chemotherapy

The optimal timing in which to use intensive chemotherapy and autologous bone marrow transplantation (BMT) in Hodgkin's disease (HD) is uncertain. In 1985, we initiated a program in which this modality was used as the initial salvage therapy in patients relapsing after combination chemotherapy. Fifty-eight patients with HD in first relapse after primary chemotherapy received conditioning with high-dose cyclophosphamide, carmustine, etoposide (VP16-213) +/- cisplatin (CBV +/- P) followed by autologous BMT. All but six of these patients were given a median of two cycles of conventional chemotherapy +/- involved field radiation therapy before CBV +/- P and autologous BMT. These measures were not used as a means for patients selection; all patients receiving such therapy ultimately were transplanted. The probability of nonrelapse mortality, progression of HD, and progression-free survival post-BMT were calculated, and prognostic factors for progression-free survival were evaluated using the Cox proportional hazards method. Treatment-related deaths occurred in only three patients. Thirteen patients have relapsed at a median 0.7 years (range 0.1 to 3.5) post-BMT. At a median follow-up of 2.3 years (range 0.4 to 7.2), the actuarial progression-free survival is 64% (95% confidence interval, 46% to 78%). In the statistical analysis, three similarly weighted but independent prognostic factors were identified: "B" symptoms at relapse, extranodal disease at relapse, and initial remission duration of less than 1 year. Patients with no risk factors had a 3-year progression-free survival of 100%, compared with 81% in patients with one factor, 40% in those with two factors, and 0% in patients with all three factors. CBV +/- P and autologous BMT is highly effective salvage therapy for HD patients in a first relapse, particularly in the subset of patients with less than two adverse factors. Therapy must be improved in the future for patients with > or = 2 adverse factors.

Judging clinical research questions: what criteria are used?

The research question is a crucial aspect of every study. Criteria for the evaluation of the merit of the study question or hypothesis have received surprisingly little attention. A set of non-methodological criteria derived from interviews with 40 researchers (clinical investigators and laboratory scientists) is presented. For both types of researcher, the terms that best described the nature of the criteria included potential impact, justification, feasibility, track record, innovation, intuitive response, aesthetics and politics. The latter three criteria are notably subjective; however all the criteria have an element of non-objectivity. There may well be a reluctance to openly acknowledge that crucial choices about what scientific questions should be explored involve criteria which are themselves not 'objective', and indeed, not even 'scientific'.

Allogeneic bone marrow transplantation for poor-prognosis non-Hodgkin's lymphoma

Twenty-one patients with non-Hodgkin's lymphoma (NHL) felt to be incurable with conventional chemotherapy underwent high-dose chemo +/- radiotherapy and allogeneic sibling donor transplant. The median patient age was 27 years (range 6-47 years); 13 were male and 8 female. By the working formulation, 6 patients at diagnosis had low-grade NHL, 8 intermediate-grade, and 7 high-grade disease. Three patients were in first remission at transplant, 3 in an advanced remission, 5 had failed to respond to initial therapy while 4 had a partial response to initial therapy, and 6 were in relapse (first or beyond). Sixteen patients were conditioned with cyclophosphamide, etoposide and total body irradiation (TBI), 4 with cyclophosphamide and TBI, and one with a combination of busulfan, melphalan and cyclophosphamide. GVHD prophylaxis was variable. At last follow-up, 8 of 21 patients remain alive and progression-free at a median of 37.5 months (range 6-58 months); actuarial event-free survival is 38% (95% confidence interval 17-58%). Thirteen patients died at a median of 2 (range 0.5-8) months post-BMT, 5 from regimen-related toxicity, 3 from acute GVHD, 2 from infections related to chronic GVHD and 3 from disease progression. Factors which were adverse predictors of progression-free survival included low-grade disease, presence of B symptoms at BMT, Karnofsky performance status at BMT and female sex. We concur with previous workers in concluding that allogeneic BMT may offer effective therapy for selected patients with incurable NHL. Major issues to be considered include timing of BMT and disease status at BMT.

Do patients' evaluations of a future health state change when they actually enter that state?

Fundamental to using utilities for future health states for clinical decision analysis is the assumption that the utilities are stable. The purpose of this study was to determine if cancer patients' prior evaluations of a treatment-induced health state remain stable when they later experience that state. Before a four-week course of radiation therapy, 66 laryngeal cancer patients evaluated three common treatment-induced outcome scenarios (mild/moderate/severe) using rating scales and the time trade-off, and provided self-assessments of voice symptoms, voice function, and general health. Evaluations and self-assessments were repeated at the end of therapy, and respondents indicated which outcome scenario described their actual end-of-therapy state. Twenty-four patients identified the mild scenario as their outcome state, 36 the moderate, and 6 the severe. No across-time differences in evaluations were detected, although significant (P < .0001) downward shifts in scores for voice symptoms (t = 5.67), voice function (t = 5.10), and general health (t = 6.69) indicated that actual change in health status had occurred. These results imply that patients' evaluations of imagined short-term health states encountered during radiation therapy for laryngeal cancer remain consistent when those states are experienced at a later time. The design of this project provides a model for determining if this consistency appears in other clinical situations.

A study of diet and breast cancer prevention in Canada: why healthy women participate in controlled trials

Little research has been undertaken to determine why healthy people agree to enroll in randomized controlled trials of cancer prevention. This study describes the beliefs of Canadian women participating in a trial designed to determine the effect of reducing dietary fat on the development of breast cancer. Healthier eating, nutritional counseling, contributing to science, and helping others were the most frequently cited advantages of participation. Weight control and general better health were specifically associated with the dietary regimens. Attending appointments and difficulties when eating out were the main disadvantages of participation. Suggestions that would promote adherence to the trial protocol also were elicited. Responses cited most often included opportunities to meet other participants, more nutritional counseling (particularly psychological tips), updates about the trial, and more recipes. Attention should be paid to these suggestions as they characterize some of the major determinants of adherence behavior.

The elusive peripheral blood hemopoietic stem cell

Long-term culture initiating cells (LTC-IC) are primitive hemopoietic progenitors that give rise to clonogenic cells when provided with a supportive feeder layer of mesenchymal cells. These LTC-IC possess many of the characteristics expected of marrow-repopulating "stem cells" including high proliferative and multilineage-differentiative capacity and resistance to 4-hydroperoxy-cyclophosphamide (4-HC) killing. In addition, stem cells are known to persist and may proliferate in murine LTC, and human marrow grown in LTC has been successfully used as hemopoietic support for myeloablative therapy. LTC-IC, as well as clonogenic precursors, circulate in normal peripheral blood, and the concentration of both progenitor types can be increased by cytotoxic chemotherapy and/or growth factors. When mobilized peripheral blood cells are used as hemopoietic support for high-dose chemo/radiotherapy, engraftment has often been more rapid than that achieved with autologous marrow. Thus, primitive hemopoietic cells circulate in human blood, which can enable hemopoietic reconstitution following aggressive therapy for malignant disease.

Autografting in chronic myeloid leukemia with cultured marrow: update of the Vancouver Study

When chronic myeloid leukemia (CML) marrow is set up in long-term culture (LTC), Philadelphia chromosome (Ph)-positive (Ph+) cells typically decline and Ph-negative (Ph-) hematopoietic cells often become detectable. In 1987, we initiated a study to evaluate the feasibility of using 10-day cultured marrow autografts to allow intensive treatment of CML. Patients were selected on the basis of a previous assessment of the frequencies of normal and leukemic LTC-initiating cells (LTC-IC) remaining in their marrow after 10 days of LTC. Of the 87 patients evaluated, 36 (41%) were considered eligible, and 22 (15 in first chronic phase [CP], Group 1; and 7 with more advanced disease, Group 2) were autografted with 10-day cultured marrow after intensive therapy. Satisfactory hematological recovery occurred in 16 patients, and of these, only Ph- cells were detected in 13 (nine in Group 1), with 76-94% Ph- cells in the other three (two in Group 1). Ph+ cells reappeared between 4 and 36 months post-autograft in all but one of the 13 patients in whom complete (morphological and cytogenetic) remission had been achieved; the remaining patient died in remission. Nine of these twelve patients were then treated with alpha-interferon (IFN-alpha) 1-3 x 10(6) units/m2, 3-7 days/week; four returned to complete remission, three developed increasing numbers of Ph+ cells, and two are still too early to evaluate. Fifteen patients (12 in Group 1) remain alive and well, nine in hematological remission (eight in Group 1), 9 to 64 months (median 28) post-autograft.(ABSTRACT TRUNCATED AT 250 WORDS)

High-dose chemotherapy and autologous bone marrow transplantation for patients with poor prognosis nonseminomatous germ cell tumours

Twenty-one patients with poor prognosis nonseminomatous germ cell tumours (six with extreme burden disease at presentation in whom partial remission had been achieved with initial induction therapy, and 15 with recurrent disease after induction therapy) were treated with high-dose chemotherapy and autologous bone marrow transplantation (BMT). The first six received etoposide 3.0 g m-2, ifosfamide 6.0 g m-2 and carboplatin 1.2 g m-2 (Regimen 1), and the subsequent 15 received etoposide 2.4 g m2 (continuous infusion), cyclophosphamide 7.2 g m-2 and carboplatin 0.8 g m-2 (Regimen 2) followed by infusion of previously stored autologous marrow. Regimen 1 was associated with considerable renal toxicity and mucositis, whereas Regimen 2 was relatively well tolerated. Two patients died as a consequence of the treatment: one of candidemia and one of interstitial pulmonary fibrosis. Only one of 17 patients who were autografted in or approaching marker remission subsequently developed disease progression (event-free survival 82%, 95% confidence interval [CI] 55% to 94%), whereas all four patients who had progressive disease at autografting subsequently developed further disease progression and died. Fourteen patients remain well and free of disease 0.5 to 6.5 years (median 3.3) post-BMT (event-free survival 67%, 95% CI 43% to 83%). A strategy of prompt reinduction followed by high-dose chemotherapy and autologous BMT at the first sign of failure of standard therapy may allow cure to be a realistic expectation.

Quality of life assessments and levels of decision making: differentiating objectives

The purpose of this paper is to examine uses of quality of life (QOL) measurements at different levels of decision making within the health care system, ranging from the micro (clinical) level, through the meso (agency, institutional or regional) level to the macro and meta (governmental) levels. We use individualized, group and population-based QOL and preference assessments as illustrative examples of ways in which QOL information and decision making level interact. We conclude that the meso and macro levels pose particularly challenging problems, and suggest that, if the primary emphasis is placed on applications of QOL assessments at the micro (clinical) level of decision making, a research agenda that is much too limited may be adopted.

Growth factor regulation of the maintenance and differentiation of human long-term culture-initiating cells (LTC-IC)

Current evidence suggests that the most primitive of hematopoietic progenitors detectable in adult human marrow are cells that can give rise to clonogenic cells for > 5 weeks in vitro when co-cultured with certain stromal cells. Procedures developed to isolate these so-called long-term culture-initiating cells (LTC-IC) in highly purified form allow their separation from most other hematopoietic cells as well as from stromal cells and their precursors also present in the marrow. We have used such procedures in conjunction with the LTC system to identify specific growth factors that support human LTC-IC maintenance and differentiation and to make comparisons with effects on later events in hematopoiesis. In some studies, soluble growth factors were added exogenously to the study cultures. In others, marrow-derived fibroblasts were genetically engineered to allow increased levels of specific human growth factors to be endogenously produced. In both of these ways, the influence of granulocyte--macrophage colony-stimulating factor (GM-CSF), G-CSF, Interleukin-3 (IL-3), IL-6, and Steel factor were investigated. Increased provision of GM-CSF alone (or in combination with other factors) enhanced terminal cell differentiation (production of granulocytes and macrophages), although the same conditions had no influence on LTC-IC differentiation (production of clonogenic cells) or on LTC-IC maintenance. In contrast, G-CSF, IL-3 and IL-6 alone (and more so when combined) in the presence of feeders effectively enhanced LTC-IC differentiation and was less active on later stages of granulopoiesis. Provision of additional exogenous Steel factor also enhanced LTC-IC differentiation, although Steel factor alone, without feeders or other growth factors, did not support either the initial differentiation of LTC-IC into clonogenic cells or their subsequent differentiation into mature granulocytes and macrophages. No combination of exogenously added growth factors was found that enhanced LTC-IC maintenance over that achieved with primary marrow feeders. However, some murine fibroblasts (including those of SI/SI origin), as well as certain exogenous growth factors (including Steel factor), were able to substitute for feeders in this regard. These observations highlight the likelihood of redundancy in factors that can elicit similar biological responses at the earliest as well as later stages of hematopoietic cell development. Nevertheless, it appears that the responses of hematopoietic cells at different stages of differentiation to any particular factor may differ markedly and that the nature of any particular response is not yet predictable from a knowledge of effects on earlier or later cell types.

Alternative mechanisms with and without steel factor support primitive human hematopoiesis

As a first approach to defining the molecular requirements for supporting human hematopoietic stem cell maintenance and differentiation in vitro, we have analyzed and compared the ability of various factors to support the maintenance and initial differentiation of human long-term culture-initiating cells (LTC-ICs), a distinct, rare primitive hematopoietic cell type whose progeny after 5 weeks include cells detectable as colony-forming cells. Normal human marrow cells highly enriched in LTC-ICs (approximately 1% pure) were placed in cultures containing either preestablished, irradiated human marrow adherent feeder layers, or feeders consisting of Steel factor-deficient SI/SI, or normal +/+ murine fibroblasts, or no feeders. In some groups, either Steel factor alone, granulocyte colony-stimulating factor (G-CSF) and interleukin-3 (IL-3), or all three factors combined were also added repeatedly. SI/SI murine fibroblasts were equivalent to +/+ controls and to normal human marrow feeders in supporting both LTC-IC maintenance and clonogenic cell output over a 5-week period. Soluble Steel factor alone could, however, effectively substitute for human marrow feeders to support LTC-IC maintenance, although clonogenic cell output was markedly reduced under these conditions. Conversely, soluble Steel factor with G-CSF and IL-3 or with feeders (or all together) did not further enhance (or depress) LTC-IC maintenance, although under these conditions clonogenic cell output was markedly increased. These findings confirm previous evidence that LTC-IC maintenance and clonogenic cell production are differentially regulated and show for the first time that LTC-IC maintenance can be supported by different nonsynergizing factors that may, but need not, include Steel factor.

Induction therapy for acute myelogenous leukemia in patients over 60 years with intermediate-dose cytosine arabinoside, mitoxantrone and etoposide

Twenty-three patients greater than age 60 years with acute myelogenous leukemia (AML) received induction therapy with continuous infusion cytosine arabinoside (1.5 g/m2/day, day 1-3), mitoxantrone (10 mg/m2/day, day 1-3) and etoposide (800 mg/m2, day 4). Patients entering complete remission (CR) were eligible to receive an identical consolidation cycle. Eighteen of the 23 patients (78%; 95% confidence interval 56% to 93%) entered CR. Twelve of these received consolidation therapy and 4 of these remain in remission at 3 to 20 months. Hematologic toxicity of the regimen was acceptable; only 1 patient died following therapy (having attained a CR). Non-hematologic toxicity was mostly mild (grade 2 or less) with one episode of grade 3 cerebellar toxicity. While this regimen induces a high CR rate in patients > age 60 years, relapses remain common and overall survival is too early to assess.

Treatment of multiple myeloma with intensive chemotherapy followed by autologous BMT using marrow purged with 4-hydroperoxycyclophosphamide

In August 1988 we began a program in which multiple myeloma patients achieving < or = 10% marrow plasma cells and > or = 50% reduction in paraprotein levels after the VAD (vincristine, doxorubicin, dexamethasone) regimen underwent bone marrow harvest, ex vivo marrow purging with 4-hydroperoxycyclophosphamide (4-HC) and marrow cryopreservation. Conditioning with a regimen of high-dose busulfan (total dose 16 mg/kg), cyclophosphamide (120 mg/kg) and melphalan (90 mg/m2) (BU + CY + MEL) followed by autologous BMT was then carried out. Seventeen of the 24 patients who received VAD (71%, 95% confidence interval [CI] 49 to 87%) were eligible for bone marrow harvest. One patient was not harvested because of non-medical reasons; two patients who underwent marrow harvest had gross plasmacytosis present in biopsies performed intraoperatively and did not undergo BMT. Fourteen patients (58%, 95% CI 37 to 78%) received BU + CY + MEL and 4-HC-purged autologous BMT. The median time to recovery of 0.5 x 10(9)/l neutrophils was 19 days (range 14 to 26) while the last platelet transfusion was given on a median of day 32 (range 10 to 46) post-BMT in the evaluable patients. The major non-hematologic toxicity was hepatic; two patients in complete remission died of hepatic veno-occlusive disease. Another patient succumbed to fungal infection despite neutrophil recovery. The remaining 11 patients achieved responses (complete in six and partial in five) associated with a normal performance status.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of nonmedical factors on family physicians' decisions about referral for consultation

OBJECTIVES

To identify nonmedical factors perceived by family physicians (FPs) and consultants as important influences on decisions about referral for consultation, to determine the relative frequency with which such factors are cited and to identify those factors ranked as most important by the FPs and consultants.

DESIGN

Survey with semistructured interview between July 1989 and April 1990.

PARTICIPANTS

A total of 41 FPs and 20 consultants who were practising or had practised previously in Nova Scotia.

INTERVENTIONS

The questionnaire comprised 10 questions: 4 were nondirective "probes" designed to elicit responses without suggesting possible answers, 2 asked the participants to rank such responses in order of importance, and 4 were "prompts" that asked for comments about a list of factors based on a review of the literature.

RESULTS

A total of 4845 discrete items were mentioned as being capable of influencing FPs' decisions about referral for consultation. Aggregation of related items resulted in a list of 35 nonmedical factors, of which 11 were identified by at least half the respondents and 14 by less than half but more than 10. These 25 factors fell into three categories: patient and family factors (e.g., patient's wishes), FP and consultant factors (e.g., FP's capabilities), and other influences (e.g., style of practice). On the basis of both frequency of identification and priority scores "patient's wishes" emerged as the most important factor. Two medical factors that were consistently cited--type of problem and age of patient--were thought to interact with the other factors.

CONCLUSION

Certain nonmedical considerations may substantially affect physicians' referral practices.

Retroviral gene transfer to primitive normal and leukemic hematopoietic cells using clinically applicable procedures

Clinical uses of gene transfer to bone marrow transplants require the establishment of a reproducible method for infecting large numbers of very primitive hematopoietic cells at high efficiency using cell-free retrovirus-containing media. In this study we report the results of experiments with preparations of a high-titer (2-5 x 10(7)/ml) helper-free recombinant neo(r) retrovirus that indicate this goal can now be achieved based on measurements of gene transfer efficiencies to cells referred to as long-term culture initiating cells (LTC-IC) because they give rise to clonogenic cells after greater than or equal to 5 wk in long-term culture (LTC). Intermittent, repeated exposure of normal human marrow mononuclear cells to virus-containing supernatant over a 3-d period of cell maintenance on an IL-3/granulocyte colony-stimulating factor (G-CSF) producing stromal layer resulted in gene transfer efficiencies to LTC-IC of 41%; a level previously obtainable only using co-cultivation infection techniques. Marrow cells enriched greater than or equal to 500-fold for LTC-IC (1-2% pure) by flow cytometry showed gene transfer efficiencies of 27% when infected in a similar fashion over a shorter period (24 h), but in the presence of added soluble IL-3 and G-CSF without stromal feeders, and this increased to 61% when Steel factor was also present during the infection period. By using a less highly enriched population of LTC-IC obtained by a bulk immunoselection technique applicable to large-scale clinical marrow harvests, gene transfer efficiencies to LTC-IC of 40% were achieved and this was increased to 60% by short-term preselection in G418. Southern analysis of DNA from the nonadherent cells produced by these LTC over a 6-wk period provided evidence of clonal evolution of LTC-IC in vitro. Leukemic chronic myelogenous leukemia LTC-IC were also infected at high efficiency using the same supernatant infection strategy with growth factor supplementation. These data demonstrate the feasibility of using cell-free virus preparations for infecting clinical marrow samples suitable for transplantation, as well as for further analysis of human marrow stem cell dynamics in vitro.

Is there a role for preference assessments in research on quality of life in oncology?

The development of ways to evaluate interventions that may have an impact on quality of life is a rapidly-developing area of research in clinical oncology, especially within the context of randomized controlled trials. We propose a role for assessments of preferences in such evaluations, including preference studies designed to assess attitudes toward the clinical acceptability of interventions, and preference trials designed to assess choice behaviour in relation to interventions. We suggest that such preference assessments represent a specific case of a more general issue: the need to develop an 'ethics of evidence', that is, standards for the creation, assessment and communication of evidence. We then outline a framework within which an 'ethics of evidence' might be developed, and suggest that the framework also may provide a useful model for the processes involved in the transfer of research results into clinical practice. As an illustration, we consider the problem of decision making in circumstances where the choice of therapy depends primarily on the patient's own preferences, as, for example, in the choice of mastectomy or breast-conserving treatment in early-stage breast cancer. The long-term goal is to develop criteria which might be used to foster shared rational decision making in such circumstances.

Collection of peripheral blood mononuclear cells as a byproduct of plateletpheresis with two different blood cell separators

Peripheral blood mononuclear cells (PBMC) were collected as a byproduct of plateletpheresis of normal blood cell donors using modifications to standard automated protocols on either the CS-3000 or Spectra blood cell separator machine. Comparison of the PBMC products obtained showed X +/- SD WBC yields of 5.3 +/- 3.4 vs. 3.8 +/- 2.0 x 10(9) with the CS-3000 and Spectra, respectively (P < .0001). The majority of the cells were lymphocytes, with 13-15% monocytes with both machines. Sixteen percent of the WBC collected with the Spectra, but only 1% of those collected with the CS-3000, were granulocytes. The CS-3000 PBMC product contained fewer RBC (0.2 +/- 0.1 x 10(11) vs. 2.4 +/- 0.6 x 10(11)) and more platelets (1.6 +/- 0.6 x 10(11) vs. 0.35 +/- 0.39 x 10(11)) in a smaller volume (40 +/- 14 ml vs. 229 +/- 37 ml) than the Spectra products. Comparison of the platelet collections harvested when PBMC were also collected to platelets harvested using standard procedures on the same machine showed no change in platelet, WBC, or RBC yields for the Spectra. A significant increase in mean WBC contamination from 40 +/- 56 x 10(7) to 112 +/- 205 x 10(7) and a small, but statistically insignificant, decrease in platelet yield from 4.1 +/- 1.2 x 10(11) to 3.9 +/- 1.8 x 10(11) was observed in the CS-3000 platelet collections when PBMC were harvested. There was no sustained change in donor lymphocyte counts and no change in acute donor side effects or time requirements when PBMC were collected.(ABSTRACT TRUNCATED AT 250 WORDS)

The human hematopoietic stem cell in vitro and in vivo

A quantitative assay for a primitive human hematopoietic cell has been developed. The cell identified has been assigned the operational designation of long-term culture (LTC)-initiating cell based on its ability when cultured on supportive fibroblast monolayers to give rise to daughter cell(s) detectable by standard in vitro colony assays. Three lines of evidence support the view that the LTC-initiating cell assay may allow the relatively specific enumeration of totipotent cells with in vivo reconstituting potential. These involve the demonstration: (1) that conditions in analogous murine long-term cultures stimulate the extensive amplification (self-renewal) of some totipotent long-term repopulating cells, (2) that most of the LTC-initiating cells in normal human bone marrow are phenotypically different from most of the colony-forming cells present in the same cell suspensions in their possession of a number of characteristics specifically associated with transplantable stem cells; and (3) that cultured marrow cells from patients with chronic myeloid leukemia which, after maintenance under LTC conditions for 10 days contain some normal LTC-initiating cells but no detectable leukemic LTC-initiating cells, can after autografting reconstitute the hematopoietic system with normal cells.

Comparison of search strategies on CD Plus/MEDLINE

OBJECTIVE

To compare two strategies for searching MEDLINE using the CD Plus/MEDLINE program on compact disc.

DESIGN

Comparison study.

INTERVENTIONS

Two search strategies were designed and executed for each of two topics (patient recruitment to clinical trials and attitudes of patients, the public and health care professionals toward clinical trials). Strategy A: searches based on key words selected from the medical subject heading (MeSH) tree structure. Strategy B: searches based on MeSH terms most frequently used to index a known set of relevant articles. Defined search restrictions were then applied. The effects of the restrictions on the absolute number of citations retrieved and on the proportion of relevant citations were assessed.

OUTCOME MEASURES

Number of articles retrieved, number of relevant articles, precision and recall of each search strategy and overlap between strategies.

MAIN RESULTS

Strategy A produced more citations than strategy B (recruitment 147 v. 38, attitude 366 v. 57) but had more inappropriate citations (recruitment 75 v. 17, attitude 265 v. 25). Both strategies produced 73 relevant recruitment citations and 101 relevant attitude citations. In the recruitment search although the precision did not differ significantly between strategies A and B the difference in recall was significant (98.6% v. 28.8% respectively, p less than 0.0001). In the attitude search strategy A had a lower precision than strategy B (27.6% v. 56.1%, p less than 0.0001) but a much higher recall (100% v. 31.7%, p less than 0.0001).

CONCLUSIONS

Strategy A would be more valuable to researchers doing extensive reviews, whereas strategy B would be useful for the busy clinician who simply wants a few appropriate references quickly and is willing to sacrifice comprehensive retrieval in the interest of efficiency.

Differential regulation of primitive human hematopoietic cells in long-term cultures maintained on genetically engineered murine stromal cells

Various growth factors are known to stimulate both early and late stages of human hematopoietic cell development in semisolid assay systems, but their role as microenvironmental regulators is poorly understood. To address this problem, we developed a novel coculture system in which highly purified primitive human hematopoietic cells were seeded onto an irradiated feeder layer of cells from a murine marrow-derived stromal cell line (M2-10B4) previously engineered by retroviral-mediated gene transfer to produce specific human factors. Effects on cells at very early, intermediate, and late stages of hematopoiesis were then evaluated by assessing the number of clonogenic cell precursors (long-term culture initiating cells [LTC-IC]), clonogenic cells, and mature granulocyte and macrophage progeny present in the cultures after 5 weeks. In the absence of any feeders, cells at all stages of hematopoiesis decreased to very low levels. In contrast, maintenance of LTC-IC was found to be supported by control murine stromal cells as effectively as by standard human marrow adherent layers. The presence of granulocyte colony-stimulating factor (G-CSF) and interleukin-3-producing M2-10B4 cells in combination was able to further enhance the maintenance and early differentiation of these cells without a decline in their proliferative potential as measured by the clonogenic output per LTC-IC. However, this effect was lost if granulocyte-macrophage CSF (GM-CSF)-producing feeders were also present. On the other hand, in the presence of GM-CSF-producing feeders, the output of mature granulocytes and macrophages increased 20-fold. These findings show that it is possible to selectively improve the maintenance of very primitive human hematopoietic cells in vitro or their output of mature progeny by appropriate manipulation of the long-term marrow culture system. Further exploitation of this approach should facilitate investigation of the mechanisms operative within the human marrow microenvironment in vivo and the design of protocols for in vitro manipulation of human marrow for future therapeutic applications.