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Biomedical subjects

J W Adamson

Publications and source records attributed to J W Adamson.

At least 55 records · Page 3Linked to original sources
PubMed1992

Production of granulocyte colony-stimulating factor and granulocyte/macrophage-colony-stimulating factor after interleukin-1 stimulation of marrow stromal cell cultures from normal or aplastic anemia donors.

We have studied stromal cell function in naive or interleukin-1 (IL-1)-stimulated (100 pg/ml) long-term marrow cultures (LTC) from 12 normal donors and 21 patients with severe aplastic anemia (AA). Conditioned media (CM) from normal LTC contained levels of erythroid burst-promoting activity (BPA) and granulocyte/macrophage (GM) colony-stimulating activity (CSA) comparable to those previously described (Migliaccio et al., [1990] Blood, 75:305-312). The addition of IL-1 to these cultures increased the level of CSA and, specifically, of granulocyte colony-stimulating factor (G-CSF) released. Anti-GM-CSF antibody neutralized BPA and CSA in normal naive LTC CM but only the CSA in the CM from IL-1-stimulated LTC. Since the concentrations of GM-CSF, as detected with a specific immunoassay, did not increase after IL-1 treatment, these data suggest that IL-1-stimulated cultures contain an unidentified growth factor having BPA. CM from AA stromal cells contained levels of CSA comparable to those observed in normal stromal cell CM but had significantly lower levels of BPA. Neither anti-GM-CSF nor anti-IL-3 antibodies neutralized the BPA in AA stromal cell CM. This activity may be related to that found in the CM of IL-1-treated normal stromal cells. In nearly 50% of stromal cell cultures of AA patients, addition of IL-1 failed to increase the BPA, CSA, or G-CSF. The presence of an inhibitor in naive or IL-1-treated AA stromal cell CM was excluded by adding the CM to IL-3-stimulated cultures. These findings suggest that G-CSF and GM-CSF genes are differentially regulated in the marrow microenvironment. Furthermore, a marrow microenvironment, deficient in BPA production and, in some cases, unresponsive to IL-1 could contribute to marrow failure in some patients with AA.

Anemia, Aplastic↗
PubMed1992

A comparison of the responses to recombinant human erythropoietin in normal and uremic subjects.

The erythropoietic response to graded doses of recombinant human erythropoietin (epoetin alfa) was assessed in 24 hemodialysis patients by quantitative ferrokinetic studies, and measurement of the reticulocyte count and plasma levels of transferrin receptor protein. These responses were compared to those of 22 normal subjects. Epoetin alfa was given intravenously at 15, 50 or 150 U/kg every other day for four injections. Three patients with chronic renal failure were restudied after renal function was restored following renal transplantation. The results of these three different measurements of erythroid function showed that the acute response to recombinant human erythropoietin was similar in normal subjects and patients with renal failure. We conclude that chronic uremia does not alter the responsiveness to erythropoietin in vivo.

Anemia↗
PubMed1992

Effectiveness of recombinant human erythropoietin therapy in myelodysplastic syndromes.

In an attempt to determine predictors of response to recombinant human erythropoietin (r-HuEPO) therapy in 20 patients with various subtypes of myelodysplastic syndrome (MDS), plasma concentrations of transferrin receptor protein were measured before and after 4 doses of r-HuEPO. An r-HuEPO dosage of 150 U/kg was administered subcutaneously 3 times weekly and increased to 300 U/kg in patients who failed to raise plasma concentrations of transferrin receptor protein by at least one third. Ten (50%) patients had an effective clinical response to therapy by reducing (greater than 50%) or eliminating transfusion requirements, or by showing an improvement in haematocrit of greater than or equal to 6 percentage points. Changes in plasma transferrin receptor protein concentrations failed to predict which patients would eventually respond to r-HuEPO therapy. A subset of MDS patients demonstrated a delayed response to therapy in order to achieve a satisfactory clinical outcome. Precise predictors of response, either laboratory or clinical, remain to be determined. Continued research is warranted in this group of patients in order to specifically target r-HuEPO therapy. It is, however, likely that r-HuEPO therapy will have an effective and important role in this subset of MDS patients.

Anemia↗
PubMed1991

Response to erythropoietin in erythroid subclones of the factor-dependent cell line 32D is determined by translocation of the erythropoietin receptor to the cell surface.

Regulation of the expression of the erythropoietin (Epo) receptor (EpoR) gene is under the control of transcriptional regulatory factor GATA-1. GATA-1 is expressed widely among the nonerythroid, factor-dependent subclones of the interleukin 3-dependent mouse cell line 32D. Consequently, to determine whether GATA-1 and EpoR gene expression are linked even in nonerythroid cells, we have studied the correlation of GATA-1 expression with expression and function of EpoR in these cell lines. EpoR mRNA (by RNase protection analysis) and EpoR protein (by specific antibody immunoprecipitation of metabolically labeled EpoR protein) were detectable not only in 32D and 32D Epo (an Epo-dependent subclone) but also in 32D GM, a subclone dependent for growth on granulocyte/macrophage colony-stimulating factor. EpoR mRNA also was detectable by PCR in 32D G, a subclone dependent for growth on granulocyte colony-stimulating factor. However, only 32D Epo cells bound 125I-labeled Epo and expressed EpoR protein on the cell surface, as determined by immunoprecipitation of surface-labeled proteins. These results indicate that, in these factor-dependent cell lines, the major regulatory step determining the erythroid-specific response to Epo is the efficiency of EpoR protein translocation to the cell surface. Mechanisms that could affect lineage-specific translocation are the presence of a chaperone protein, erythroid-specific editing of EpoR mRNA, or altered processing of the EpoR protein to the cell surface. In this model, lineage-restricted responses to growth factors such as Epo are determined not by expression of the genes for growth factor receptors but, rather, by appropriate processing of the receptor protein.

Animals↗
PubMed1991

Stem cell factor induces proliferation and differentiation of highly enriched murine hematopoietic cells.

Recombinant rat stem cell factor (SCF) was studied for its ability to stimulate the growth of murine hematopoietic progenitor cells and to generate colony-forming cells (CFC) from highly enriched populations of hematopoietic cells. In serum-deprived cultures, SCF alone stimulated few colonies but interacted with a number of other hematopoietic growth factors, particularly interleukin 3, to promote colony formation. The most marked effect was on the generation of mixed-cell colonies. Hematopoietic cells were sorted into wheat-germ agglutinin-negative, monocyte-depleted, rhodamine 123 (Rh123)-bright or Rh123-dull cells. Historically, Rh123-bright cells are capable of short-term (less than 1 mo) marrow engraftment, whereas among Rh123-dull cells are cells capable of long-term marrow engraftment. Enriched cells (2.5 x 10(3) were placed into serum-deprived liquid cultures with various hematopoietic growth factors. Initially, the Rh123-bright and Rh123-dull cells had few CFC but, in the presence of interleukin 3 and SCF, Rh123-bright cells gave rise to greater than 15,000 granulocyte/macrophage CFC, greater than 1500 erythroid burst-forming cells, and greater than 700 mixed-cell CFC by day 5. In contrast, Rh123-dull cells proliferated only in the presence of interleukin 3 and SCF, but total cell numbers rose to a peak of 18,000 by day 21, and one-third of the cells were CFC. Thus, SCF, in combination with other growth factors, can generate large numbers of CFC from pre-CFC and appears to act earlier than hematopoietic growth factors described to date.

Animals↗
PubMed1991

Cytokine biology. Implications for transfusion medicine.

The development and widespread availability of recombinant products will effect blood centers through reduced product use, replacement of current products, and novel applications of new products. The greatest amount of clinical experience to date has dealt with the use of recombinant human erythropoietin (r-HuEPO) in the treatment of anemia in end-stage renal failure. Data also support its use in anemia associated with acquired immune deficiency syndrome (AIDS), cancer, and chronic inflammatory diseases. This article will focus on the effect of erythropoietin on the demand for erythrocyte use.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Effects of recombinant human stem cell factor (SCF) on the growth of human progenitor cells in vitro.

We have studied the effect of recombinant human Stem Cell Factor (SCF) on the growth of human peripheral blood, bone marrow, and cord blood progenitor cells in semisolid medium. While SCF alone had little colony-stimulating activity under fetal bovine serum (FBS)-deprived culture conditions, SCF synergized with erythropoietin (Epo), granulocyte/macrophage colony-stimulating factor (GM-CSF), and interleukin 3 (IL-3) to stimulate colony growth. Colony morphology was determined by the late-acting growth factor added along with SCF. Of all the combinations of growth factors, SCF plus IL-3 and Epo resulted in the largest number of mixed-cell colonies--a larger number than observed with IL-3 and Epo alone even in FBS-supplemented cultures. These results suggest that SCF is a growth factor that more specifically targets early progenitor cells (mixed-cell colony-forming cells) and has the capacity to synergize with a wide variety of other hematopoietic growth factors to cause the proliferation and differentiation of committed progenitor cells. Our studies indicate that SCF may be the earliest acting growth factor described to date.

Bone Marrow Cells↗
PubMed1991

Erythropoietin: its role in the regulation of erythropoiesis and as a therapeutic in humans.

The application of recombinant DNA technology to the field of hematology has contributed greatly to our understanding of Epo gene structure and regulation, cellular expression and regulation of hormone production, pharmacokinetics, receptor biology, and ultimately, the value of this hormone as a therapeutic treatment. Areas that will undoubtedly prove fruitful for future research include the mechanisms by which hypoxia influences gene expression, structure/function relationships of the Epo molecule, mechanisms of transmembrane signaling and nuclear activation, and the application of rHuEpo in the treatment of other anemias. Epo is but one example of the contribution that modern biology has made to the understanding of hematopoietic regulation and to the availability of these regulators for the treatment of human disease.

Amino Acid Sequence↗
PubMed1991

In vitro differentiation and proliferation of human hematopoietic progenitors: the effects of interleukins 1 and 6 are indirectly mediated by production of granulocyte-macrophage colony-stimulating factor and interleukin 3.

The effect of recombinant human interleukin (IL)-1 and IL-6 on the differentiation and proliferation in vitro of human granulocyte-macrophage (GM) and erythroid progenitors has been investigated in either fetal bovine serum (FBS)-supplemented or FBS-deprived cultures. Sources of progenitor cells were unfractionated bone marrow cells or marrow cells depleted of adherent and/or T cells. Each interleukin was investigated either alone or in combination with GM-colony-stimulating factor (CSF), IL-3 and erythropoietin (Epo), or granulocyte (G)-CSF. In FBS-supplemented cultures of unfractionated marrow cells, IL-1 induced optimal GM colony growth and increased by 50% the number of erythroid bursts that formed in the presence of Epo. The addition to these cultures of a neutralizing anti-GM-CSF monoclonal antibody or of an anti-IL-3 serum decreased the growth of GM colonies by 80% and 40%, respectively. Under the same conditions, IL-6 had no effect on GM colony growth but increased by 90% the number of erythroid bursts. This effect was partially (40%) neutralized by addition of anti-IL-3 serum. IL-1 and IL-6 were weak stimuli, or had no effect at all, either alone or in combination with GM-CSF and IL-3 in FBS-deprived cultures or in FBS-supplemented cultures of nonadherent or nonadherent, T-cell-depleted marrow cells. IL-1 and IL-6 had no effect, either alone or in combination with IL-3, in maintaining the number of progenitor cells in short-term liquid suspension cultures. These results indicate that the actions of IL-1 and IL-6 on hematopoiesis are mainly indirect and mediated by the production of GM-CSF and/or IL-3 by accessory cells. However, neither IL-1 nor IL-6 alone is sufficient to stimulate production of growth factor(s) by accessory cells, and at least a second stimulus, provided by FBS, is also required. These data are in agreement with a multisignal model of regulation of the expression of growth factor genes.

Antibodies↗
PubMed1990

Muramyl dipeptide induces production of hemopoietic growth factors in vivo by a mechanism independent of tumor necrosis factor.

Monocyte products including TNF and IL-1 can stimulate hemopoietic growth factor production in vitro and in vivo. Endotoxin-resistant C3H/HeJ mice have a cellular defect in the regulation of TNF production and provide a model in which to examine the relative importance of TNF and IL-1. To assess the relative role of TNF and IL-1, we injected the synthetic bacterial cell wall derivative muramyl dipeptide (MDP) or LPS into C3H/HeJ mice. Both MDP and LPS stimulated hemopoietic growth factor production in a dose-dependent manner. Northern blot analysis of splenic and lung mRNA revealed that MDP treatment induced granulocyte-macrophage CSF and macrophage-CSF transcripts, whereas LPS treatment induced macrophage-CSF transcripts. Messenger RNA for granulocyte-CSF, IL-3, IL-4, and IL-5 was not detected in control or treated mice. MDP treatment induced IL-1 mRNA but not TNF mRNA, and TNF bioactivity was not detected in the serum of MDP-treated mice. In contrast, LPS treatment induced TNF production. These results identify the hemopoietic growth factors induced by MDP and LPS in vivo, and suggest that MDP stimulates growth factor production by a mechanism independent of TNF.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

Comparative analysis of hematopoietic growth factors released by stromal cells from normal donors or transplanted patients.

We compared the erythroid burst-promoting activity (BPA) and colony-stimulating activity (CSA) released under serum-deprived conditions by stromal cells derived from nine normal subjects and from nine patients after bone marrow transplantation. BPA and CSA were defined according to the capacity of the conditioned media (CM) to stimulate formation of erythroid bursts and granulocyte/macrophage (GM) colonies in serum-deprived cultures of nonadherent marrow cells. Six patients (group A) failed to establish or maintain successful allografts during the study. The remaining three (group B) did not experience problems with engraftment. CM from all stromal cell cultures contained detectable levels of BPA. Preincubation of the CM with an anti-GM colony-stimulating factor (GM-CSF) monoclonal antibody (MoAb), but not with a rabbit anti-interleukin-3 (IL-3) serum, reduced BPA by an average of 94%. CM from normal and group B stromal cell cultures contained detectable CSA, and the levels correlated with the amounts of granulocyte-CSF (G-CSF) detected by a specific bioassay. G-CSF was not detectable in medium conditioned by stromal cells from transplanted patients with poor marrow function. These results indicate that CM from stromal cells from normal subjects and transplanted patients with good marrow function contain both GM-CSF and G-CSF, while CM from stromal cells from transplanted patients with poor marrow function contain detectable levels of GM-CSF only. The reduced capacity of these stromal cells to produce G-CSF is associated with a reduced capacity of the CM to sustain GM colony formation and may be associated with the inability of these patients to sustain their neutrophil counts in vivo.

Biological Assay↗
PubMed1990

The use of recombinant human erythropoietin in humans.

Recombinant human erythropoietin (rhEPO) has now been in clinical trials for over three years. It has been shown to be nearly uniformly effective in correcting the anaemia of patients on haemodialysis or patients with progressive chronic renal failure not yet on dialysis. Preliminary results indicate that rhEPO is effective in increasing the ability of individuals to donate blood for self-use and early trials have shown the drug to increase the haematocrit in patients with rheumatoid arthritis. Trials in patients with anaemia associated with cancer or myelodysplastic syndromes are warranted. rhEPO will have a major impact as a therapeutic, particularly in patients with renal disease.

Anemia↗
PubMed1990

Recombinant erythropoietin improves exercise capacity in anemic hemodialysis patients.

The objective of this study was to quantitate the improvement in exercise capacity produced in anemic chronic hemodialysis (HD) patients after correction of their anemia with recombinant human erythropoietin (rHuEPO). The maximal exercise capacity and quadriceps strength of 19 anemic HD patients was tested before and after correction of the anemia with rHuEPO. A progressive work exercise protocol (PWET) on a cycle ergometer was used to compare measurements of maximal oxygen uptake (VO2max), maximal heart rate, and subjective assessment of fatigue during the test. Measurements of quadriceps strength were performed before the cycle ergometer studies. At baseline, all patients had reduced VO2max (15.3 +/- 5.4 mL/kg/min) and maximal exercise heart rates (138.5 +/- 23.9 beats/min). rHuEPO increased the mean hematocrit from 21.2% to 35%, and this was associated with a 17% increase (P less than 0.0005) in the VO2max. At any specified work load, rHuEPO treatment decreased heart rate, minute ventilation, and the subjective perception of fatigue. Both isometric and isokinetic measurements of quadriceps strength were improved following administration of rHuEPO. The maximal exercise heart rate was decreased in comparison to the baseline measurements (P less than 0.04), suggesting that in contrast to normal subjects, HD patients stop exercise before oxygen transport limitations are reached. In this unselected group of chronic HD patients, rHuEPO produced clinically significant improvements in both aerobic exercise capacity and isometric and isokinetic quadriceps strength. The improvement in aerobic capacity was substantially less than would have been expected from the correction of a comparable degree of anemia in non-HD patients. None of the 19 treated patients attained the exercise performance level predicted for a sedentary normal subject.

Adult↗
PubMed1990

Hypertension following erythropoietin therapy in anemic hemodialysis patients.

Recombinant human erythropoietin (rHuEpo) corrects the anemia of end-stage renal disease. However, hypertension has been observed as an adverse effect of increasing red cell mass. In our study, 44 of 63 patients (70%) treated with rHuEpo had an increase in mean arterial pressure greater than 10 mm Hg or required new or additional hypertensive medications. Retrospective analysis disclosed that increasing blood pressure was associated with pretreatment hematocrit level less than or equal to 0.20 (P = .05) and dependency on red cell transfusions (P less than .01). Factors not associated with hypertension included the rate of rise of the hematocrit, the net rise in hematocrit, age, sex, the number of years on dialysis, the presence or absence of kidneys, smoking, or the presence of pretreatment hypertension. Noninvasive hemodynamic studies in eight normotensive patients before and after improvement of the anemia demonstrated a normalization of the decreased peripheral vascular resistance and a reduction toward normal in the elevated cardiac output. In three of these patients, clinical hypertension subsequently evolved. Follow-up hemodynamic studies in nine other patients receiving new or additional antihypertensive medications were difficult to interpret. Although the hypertension can be controlled with routine medication, hypertensive encephalopathy may occur if the blood pressure increases rapidly when the hematocrit increases with rHuEpo therapy.

Adult↗
PubMed1990

Treatment of the anemia of chronic renal failure with recombinant human erythropoietin.

The anemia of chronic renal failure can now be effectively treated with recombinant human erythropoietin when given in adequate doses. This hormone replacement therapy is associated with significant clinical benefits but it requires adequate iron stores for maximal effectiveness, it may result in elevation in diastolic blood pressure, and the response may be blunted by the presence of infection or inflammation.

Anemia↗