Search PubMed⌕ Search

Biomedical subjects

N G Testa

Publications and source records attributed to N G Testa.

At least 145 records · Page 8Linked to original sources
PubMed1983

Stromal colonies from mouse marrow: characterization of cell types, optimization of plating efficiency and its effect on radiosensitivity.

Modifications to the colony assay in vitro for stromal progenitor cells in mouse femoral marrow have been studied so as to optimize the efficiency of colony formation (CFE). The highest reproducible concentration achieved was about 30 colonies (containing fibroblasts, macrophages and endothelioid cells) per 10(6) nucleated marrow cells (range 20-50) in mice 3-4 months old, and higher by 50% in mice 14-15 months old. Each of many slight technical modifications could reduce these values by more than 30%. The importance of optimization was demonstrated by a reduced radiosensitivity when the CFE was reduced by a factor of 3 using alpha-medium stored at 4 degrees C for 15 days. The D0 value was 3.9 +/- 0.8 Gy compared to 1.6 +/- 0.1 Gy using freshly prepared medium, and this could be due to the selection of a radioresistant subpopulation. The modifications studied may partly explain the marked variations in CFE and in radiosensitivity reported in the literature.

Animals↗
PubMed1983

The response of stromal progenitor cells in mouse marrow to graded repeated doses of X rays or neutrons.

After four repeated doses of 1.5 Gy X rays to mice (3-week intervals), the number of colonies containing fibroblasts that could be grown in vitro from femoral marrow recovered to control numbers by 80 days. After four higher doses, recovery was incomplete, and after four doses of 4.5 Gy, the number was half of the control level up to 1 year after irradiation. After four doses of 14.7 MeV neutrons, no threshold was detected for this late effect, and the RBE was about 2 at 4.5 Gy X rays and about 6 at 1.5 Gy X rays. The RBE for the acute effect on the stromal progenitor cells was also about 2 at 4.5 Gy X rays. The stromal progenitor cells could not be spared relative to hemopoietic stem cells (CFU-S) after neutrons, in contrast to the sparing observed after low-dose fractions of X rays. Experiments with local X irradiations of the leg, and with subcutaneous transplants of femora, revealed no significant recovery of stromal progenitor cells due to migration. However, recovery in situ could be enhanced slightly by marrow grafts i.v.

Animals↗
PubMed1982

Long-term bone-marrow damage in children treated for ALL: evidence from in vitro colony assays (GM-CFC and CFUF).

We have studied granulocyte-macrophage progenitor cells (GM-CFC) in serial bone marrow aspirates from 43 children who had been treated for acute lymphoblastic leukaemia (ALL). All patients were in full remission, not receiving anti-leukaemic therapy and 42 out of the 43 had normal peripheral blood counts. Thirty-seven patients have received standard amounts of chemotherapy and 6 have received additional therapy for relapses occurring in the first treatment-free interval. In the former group estimation of GM-CFC incidence did not provide evidence of long-term residual bone-marrow damage. In the latter, however, the mean incidence of GM-CFC was significantly reduced. This reduction was also apparent when the incidence of GM-CFC was related to the incidence of non-haemopoietic progenitor cells within the marrow (CFU-F).

Antineoplastic Agents↗
PubMed1982

The relative spatial distribution of erythroid progenitor cells (BFUe and CFUe) in the normal mouse femur.

Femoral mouse bone marrow cells were separated into axial and marginal fractions, in order to investigate the relative concentration of erythroid progenitor cells (BFUe and CFUe) with respect to their location across the diameter of the femur. Two areas of high incidence of early progenitor cells (BFUe) were identified: one lying near the bone surface with a peak at about 410 micrometers radial distance from the axis of the bone; the other nearer the centre of the bone with a peak at about 270 micrometers. The more immature BFUe were found in higher proportion in the marginal peak. In contrast, CFUe, apart from very low concentration values in the vicinity of the bone surface, demonstrated a fairly uniform distribution throughout the marrow. The present results indicate that the distribution of erythroid progenitor cells within the bone marrow is not random. The haemopoietic tissue seems to exhibit a well-defined structure that may be relevant in regulating proliferation and differentiation processes.

Animals↗
PubMed1982

The regulation of hemopoiesis in long-term bone marrow cultures. III. The role of burst forming activity.

The addition of burst forming activity (BFA) from mouse spleen conditioned medium (MSCM) to serum-free long-term cultures induced the formation of day 4 BFUE demonstrating that MSCM has an erythropoietin-independent activity on erythroid development. Conditioned medium (CM) from long-term mouse marrow cell cultures was inhibitory to burst formation at concentrations as low as 0.01% when bone marrow cells were used as the external source of BFA, whereas significant levels of inhibition were apparent only at 100-fold greater concentrations of CM in cultures containing MSCM. CM did not inhibit erythropoietin-stimulated erythropoiesis in liquid subcultures of long-term culture cells nor did it stimulate erythroid maturation in the absence of erythropoietin. Adherent cells from the long-term cultures, used as feeder cells, were more active than normal bone marrow cells in enhancing erythroid burst formation.

Animals↗
PubMed1981

Friend disease in vitro.

In long-term marrow cultures, hemopoiesis can be maintained for several months, although erythropoiesis is normally suppressed at the most primitive level of development (the erythroid colony-forming cells). Infection of these cultures with a viral complex combining helper-independent murine leukemia virus (F-MuLV) and a spleen focus-forming virus (SFFVp) results in a productive infection of both the replication defective SFFVp and the F-MuLV. After infection, the cultures show a dramatic elevation in the numbers of late erythroid progenitor cells (CFU-E), many of which will grow in the absence of added erythropoietin, and a transient erythropoietin, independent erythropoiesis, including the production of mature, enucleated erythrocytes. Hemopoiesis eventually declines, with no evidence for the generation of Friend tumor cells. When erythropoiesis is induced in the long-term cultures by addition of anemic mouse serum before infection by polycythemia-inducing Friend virus, the generation of erythropoietin-independent CFU-E and erythrocyte formation is followed by the sustained production (greater than 40 wk) of primitive erythroid cells with low spontaneous levels (less than 5%) of hemoglobinization. Although these cells will produce spleen colonies in irradiated mice and can be cloned in soft-gel media, they do not produce autonomous, permanently growing cell lines in vitro, i.e., they retain a dependency upon the marrow-adherent layer for their continued growth. However, following a further passage on a "virgin" marrow environment, permanent cell lines can be established that are able to grow independently of environmental influences. Thus, this system is the first description of a complete in vitro system for the reproducible production and isolation of Friend virus-induced erythroid cell lines.

Anemia↗
PubMed1981

Molecular and cell biologic aspects of erythropoiesis in long-term bone marrow cultures.

In long-term marrow cultures, proliferation and differentiation of hemopoietic stem cells occurs for several months. Normally, only the most primitive erythroid progenitor cells are produced (the BFU-E). Following treatment with anemic mouse serum (AMS) or normal mouse serum plus erythropoietin, the BFU-E mature into CFU-E, which then go to produce mature nonnucleated red cells. This development is associated with the production of adult type hemoglobin. Furthermore, erythropoiesis and granulopoiesis occur in association with discrete cellular elements of the adherent cell layer in the long-term culture. Following treatment with AMS, erythropoiesis is enhanced while granulopoiesis is depressed, with no apparent competition at the stem cell or progenitor cell level.

Adipose Tissue↗
PubMed1981

The production of putative osteoclasts in tissue culture - ultrastructure, formation and behavior.

A system for culture of cat bone marrow produces multinucleate cells (50-100 nuclei) of large proportions (300 micrometer diameter). Scanning and transmission electron microscopy indicates that these cells (not virally induced syncytia) are true osteoclasts, which exhibit ultrastructural aspects of bone resorption (ruffled border and clear zones in TEM section, active spatulate cytoplasmic extensions in the SEM) even after 6 weeks culture on a plastic substratum. Observations have also been made regarding the formation of the multinucleate cells from apparently specific mononuclear precursors, and the behaviour of these cells on various substrata is also reported.

Animals↗
PubMed1980

Malignant myelomonocytic cells after in vitro infection of marrow cells with Friend leukaemia virus.

Infection of long-term BDF1 marrow cultures with Friend leukaemia virus complex (FLV) induced transformed cells with myelomonocytic characteristics, which were isolated only 14 days after the viral infection. Criteria for transformation were growth in suspension cultures and high plating efficiency in agar. The lymphatic leukaemia virus (LLV) replicates in these suspension cultures, but the spleen focus-forming virus (SFFV) component of the FLV complex has not been detected. Injection of the transformed cells into syngeneic neonatal or adult mice leads to the development of leukaemia which can be demonstrated to be of donor origin by the presence of two metacentric marker chromosomes which are also seen in the cultured cells.

Agar↗
PubMed1980

Role of purified erythropoietin in the amplification of the erythroid compartment.

A single dose of Myleran induced a prolonged depletion of multi-potential haemopoietic cells and of early erythroid precursors to levels between 2 and 6 of control. In these mice, a priming dose of highly purified erythropoietin (Epo) or of any of 3 Epo preparations from different sources, and having different specific activities, increased the magnitude of the response to a test dose of Epo by erythropoietin responsive cells (ERC) in the hypertransfused mouse assay. As significant feeding into the ERC compartment from the most immature cells is unlikely because of the depletion induced by the Myleran, it may be concluded that highly purified Epo, not contaminated with other biologically active molecules, has a dual effect on the ERC: it causes increased amplification besides inducing differentiation into cells with the capacity to synthesize haemoglobin.

Animals↗
PubMed1979

Erythropoietin-stimulated erythropoiesis in long-term bone marrow culture.

The proliferation of multipotential haematopoietic stem cells (CFU-S) is possible in some long-term bone marrow cultures. Granulocyte and macrophage progenitor (CFU-C) and megakaryocyte precursor cells (CFU-M) are present in these cultures and undergo full development into mature cells. In contrast, while immature erythroid progenitors ('early' BFU-E) are maintained in long-term culture, none of the more differentiated progeny (CFU-E) have been detected, and no morphologically recognisable erythroid cells have been observed. We now describe a modified culture system in which the 'early' BFU-E develop into 'late' BFU-E in response to added erythropoietin. Further maturation of these cells into CFU-E and non-nucleated erythrocytes can be achieved by mechanical agitation of the long-term cultures or by transferring the cells into dishes which do not allow cell attachment to occur.

Animals↗
PubMed1978

Inhibition of haemopoietic stem cell proliferation by a diffusible product of bone marrow cells.

In a double diffusion chamber (DC) culture system bone marrow cells elaborated diffusible factor(s) that prevented spleen colony-forming cells (CFU-S), but not PHA stimulated lymphocytes, from entering cell cycle. Mature granulocytes and macrophages did not produce such factors(s). Various number of steady-state or regenerating mouse bone marrow cells were cultured in single diffusion chamber for periods up to 7 d. After the initial cell loss,the net growth of CFU-S was inversely related to both total cell number and CFU-S number in DC. Diffusible factors rather than cell-to-cell contact appeared to be involved in the inhibition, even though we were not able to demonstrate inhibition of net growth of CFU-S with the double chamber approach.

Animals↗
PubMed1977

Bone marrow culture studies in refractory cytopenia and 'smouldering leukaemia'.

As an adjunct to conventional haematological and cytogenetic data, 22 cases of refractory cytopenia, and five with chronic myelomonocytic leukaemia, (CMML) were studied by bone marrow culture. Cultures from II such patients without an excess of marrow myeloblasts usually showed low, or undetectable, numbers of cells capable of giving rise to colonies of granulocytes and/or macrophages (CFUc) but near-normal numbers of cluster-forming cells and cells capable of forming erythroid colonies (CFUE). Those with similar blood pictures, but in whom the marrow contained a slight excess of myeloblasts (II cases), showed a more profound defect in growth patterns: low or undetectable numbers of CFUC, clusters and CFUE, results similar to those found in acute myeloblastic leukaemia, into which three of this group evolved. The patients with CMML gave comparatively normal CFUC, cluster and CFUE growth patterns.

Blood Platelets↗