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Biomedical subjects

L Souza

Publications and source records attributed to L Souza.

At least 37 records · Page 2Linked to original sources

Effects of recombinant growth factors on radiation survival of human bone marrow progenitor cells.

The purpose of this study was to evaluate the individual radioprotective effects of 4 distinct purified recombinant human hematopoietic growth factors, namely recombinant human granulocyte-macrophage colony stimulating factor (rGM-CSF), recombinant human granulocyte colony stimulating factor (rG-CSF), recombinant human interleukin 1 (rIL-1), and recombinant human interleukin 2 (rIL-2) on human myeloid (CFU-GM) and erythroid (BFU-E) bone marrow progenitor cells. We demonstrate that (a) preconditioning with rGM-CSF, rG-CSF, or rIL-1 enables CFU-GM to repair sublethal radiation damage and renders CFU-GM less radiosensitive, (b) preconditioning with rGM-CSF or rIL-1 enables BFU-E to repair sublethal radiation damage, and (c) preconditioning with rIL-2 does not increase the radiation survival of CFU-GM or BFU-E. The effects of recombinant growth factors, in particular rGM-CSF, on the radiation damage repair, radiosensitivity, and proliferative activity of bone marrow progenitor cells resulted in a substantial increase in the mean numbers of progenitor cell-derived hematopoietic colonies in irradiated marrow samples. The effects of rGM-CSF on the radiation response of CFU-GM and BFU-E, and the effects of rG-CSF as well as rIL-1 on the radiation response of CFU-GM did not appear to require the presence of T-cells/T-cell precursors, NK-cells, B-cells/B-cell precursors, monocytes, macrophages, MY8 antigen positive non-CFU-GM myeloblasts, promyelocytes, myelocytes, metamyelocytes, granulocytes, or glycophorin A positive erythroid cells since virtually identical results were obtained with unsorted marrow samples or highly purified fluorescence activated cell sorter (FACS) isolated progenitor cell suspensions. To our knowledge, this report represents the first study on recombinant human growth factor-induced modulation of the radiation responses of normal human bone marrow progenitor cells.

Cell Survival↗

The use of granulocyte colony-stimulating factor to increase the intensity of treatment with doxorubicin in patients with advanced breast and ovarian cancer.

Granulocyte colony stimulating factor (G-CSF) was given to 17 patients with advanced breast and ovarian cancer in order to increase the intensity and effectiveness of chemotherapy. Treatment with doxorubicin, at doses of 75 mg m-2 (n = 4 patients), 100 mg m-2 (n = 5), 125 mg m-2 (n = 6) and 150 mg m-2 (n = 2), was followed by infusion of G-CSF for 11 days. G-CSF administration resulted in a return of the absolute neutrophil count to normal or above normal levels within 12-14 days at all dose levels of doxorubicin used and allowed the administration of up to three cycles of high dose chemotherapy at 14 day intervals. An absolute neutrophil count greater than 2.5 x 10(9)l-1 was not reached until day 19-21 after 75 mg m-2 of doxorubicin given without G-CSF. At doses of doxorubicin of 125 mg m-2 and 150 mg m-2 all tumours regressed rapidly, although there was marked epithelial toxicity. The overall response rate in patients with advanced breast cancer was 80% with a median time to progression of 6 months. Two months after doxorubicin-G-CSF therapy there was a pronounced improvement of symptoms compared with before treatment. Thus the effectiveness of chemotherapy may be enhanced and treatment duration shortened by the use of G-CSF infusions. Further studies of this promising approach are warranted.

Adult↗

The kinetics of human granulopoiesis following treatment with granulocyte colony-stimulating factor in vivo.

Cell proliferation in the bone marrow and blood of two patients with metastatic breast cancer who were treated with granulocyte colony-stimulating factor was studied by using [3H]thymidine labeling and autoradiography. Additionally, the fate of neutrophils labeled with 99mTc-hexamethylpropyleneamineoxime was observed following granulocyte colony-stimulating factor infusion. Proliferation increased in all stages of granulopoiesis, but a significant amount of the increased production stemmed from a greater input to the myeloblast compartment. Changes in the myelogram combined with the increased labeling indicated a faster throughput of cells, which resulted in labeled cells appearing in the circulation within 1 day compared to the normal 4 or 5 days. The 99mTc studies demonstrated no sequestration of circulating neutrophils by spleen, lungs, or liver. The half-life of the circulating neutrophils was not significantly changed, and calculations from the flow of labeled cells to the peripheral blood indicated an increase of 3.2 extra amplification divisions during neutrophil development. The dramatic neutrophil response to granulocyte colony-stimulating factor can therefore be accommodated by a relatively modest increase in granulopoietic activity.

Adult↗

Replication-defective vectors of reticuloendotheliosis virus transduce exogenous genes into somatic stem cells of the unincubated chicken embryo.

Replication-defective vectors derived from reticuloendotheliosis virus were used to transduce exogenous genes into early somatic stem cells of the chicken embryo. One of these vectors transduced and expressed the chicken growth hormone coding sequence. The helper cell line, C3, was used to generate stocks of vector containing about 10(4) transducing units per ml. Injection of 5- to 20-microliters volumes of vector directly beneath the blastoderm of unincubated chicken embryos led to infection of somatic stem cells. Infected embryos and adults contained unrearranged integrated proviral DNAs. Embryos expressed the transduced chicken growth hormone gene and contained high levels of serum growth hormone. Blood, brain, muscle, testis, and semen contained from individuals injected as embryos contained vector DNA. Replication-defective vectors of the reticuloendotheliosis virus transduced exogenous genes into chicken embryonic stem cells in vivo.

Animals↗

Granulocyte colony-stimulating factor stimulates recovery of granulocytes in patients receiving dose-intensive chemotherapy without bone marrow transplantation.

Bone marrow colony-stimulating factors (CSF) ameliorate hematologic toxicity of standard chemotherapy regimens and may allow relatively safe use of intensive and more efficacious doses of anticancer drugs. Twenty-four patients with cancers for which no standard regimens were likely to be effective received repeated courses of a combination of cisplatin (150 mg/m2), etoposide (1,500 mg/m2), and cyclophosphamide (5,000 mg/m2) at doses for which bone marrow transplantation is usually used. A total of 10 patients received escalating doses of recombinant human granulocyte CSF (rhG-CSF); 11 patients receiving identical chemotherapy and supportive therapy without rhG-CSF served as controls for the first cycle of therapy. Five of these patients and 3 additional patients also served as their own controls, receiving rhG-CSF for all cycles after the first. No patient received bone marrow transplantation. rhG-CSF shortened the median duration of severe granulocytopenia (less than or equal to 100/mm3) in a dose-related fashion (P less than .03; Kruskal-Wallis test). Patients not receiving rhG-CSF had a median of 8.5 days of granulocytopenia. Those receiving 40 micrograms/kg of rhG-CSF for approximately 20 days from the third day after chemotherapy had a median of 7.0 days (P less than .23) and those receiving 60 micrograms/kg had a median of 5.5 days (P less than .007) of granulocytopenia. An rhG-CSF dose of 20 micrograms/kg had no effect. Recovery to a granulocyte count of at least 500/mm3 took a median of 12 days in the control group and 8 days (P less than .03) in patients receiving rhG-CSF at a dose of 60 mg/kg. The duration of antibiotic therapy (a median, 9.0 days v 5.0 days) was shortened with the two higher and effective doses of rhG-CSF compared with control patients. The duration of hospitalization (median of 20 days v 19 days) was not shortened. These findings that rhG-CSF decreases the risk of granulocytopenia associated with this particular dose-intensive chemotherapy regimen therapy administered without bone marrow transplantation.

Antineoplastic Combined Chemotherapy Protocols↗

The hematologic effects of chronic administration of the monokines tumor necrosis factor, interleukin-1, and granulocyte-colony stimulating factor on bone marrow and circulation.

Monokines may contribute to the regulation of hematopoiesis and circulating numbers of leukocytes during chronic inflammation. The hematologic effects of daily intravenous injection of the recombinant monokines tumor necrosis factor (TNF), interleukin-1 (IL-1), and granulocyte-colony stimulating factor (G-CSF) were therefore studied in the bone marrow and circulation of rats over the course of a week. TNF induced daily neutrophilia and lymphopenia with no evidence of tachyphylaxis. TNF also induced a slight decrease in early myeloid forms in the marrow, but, more strikingly, induced a marked erythroid hyperplasia of late normoblasts, although no changes other than a slight reticulocytosis were noted in the peripheral red blood cell compartment. IL-1 also induced daily neutrophilia and lymphopenia with no evidence of tachyphylaxis. IL-1 differed from TNF in the induction of a significant myeloid hyperplasia and in the lack of any effect on the erythroid elements of the marrow. The lack of tachyphylaxis to the chronic administration of both TNF and IL-1 suggests that the mechanism of endotoxin-induced tachyphylaxis is not at the level of the effector cell response to these endogenous cytokines. G-CSF induced a biphasic peripheral neutrophilia first peaking on day one, reaching a nadir on day 4, and then rising progressively again until day 7. The low level of neutrophilia on day 4 is not due to marrow depletion of neutrophils secondary to the neutrophil releasing activity of G-CSF because the marrows of G-CSF-treated rats on both days 3 and 7 contained over twice the number of mature neutrophils as controls. Thus, the trough in the neutrophilia induced by G-CSF is postulated to be due to an as-yet unidentified negative feedback mechanism that inhibits neutrophil release from the marrow.

Animals↗

Therapy for neutropenia in hairy cell leukemia with recombinant human granulocyte colony-stimulating factor.

STUDY OBJECTIVE: To determine whether recombinant human granulocyte colony-stimulating factor (G-CSF) is effective in increasing neutrophil counts in patients with hairy cell leukemia and neutropenia. DESIGN: Open label, phase I/II study of G-CSF, given by daily subcutaneous injection for up to 7 weeks. SETTING: Outpatient oncology clinic of a university medical center. PATIENTS: A consecutive sample of four patients with hairy cell leukemia complicated by severe neutropenia. Three patients completed the study; one patient was removed after 2 weeks of therapy. INTERVENTIONS: Granulocyte colony-stimulating factor was given by daily subcutaneous injection. Each patient began therapy with 1 microgram/kg body weight.d; after 1 week the dose was increased to 3 micrograms/kg.d, and 1 week later to 6 micrograms/kg.d. Therapy was continued for 5 to 6 weeks. Patients were taught self-injection, and administered treatment at home. MEASUREMENTS AND MAIN RESULTS: In three patients, an increase in absolute neutrophil counts from less than 0.9 X 10(9)/L to greater than 4.0 X 10(9)/L was noted within 2 weeks of beginning G-CSF therapy. In two patients, infections resolved during therapy. One patient developed acute neutrophilic dermatosis (the Sweet syndrome) while receiving 3 micrograms/kg.d of G-CSF, and drug therapy was discontinued. CONCLUSIONS: Granulocyte colony-stimulating factor may increase neutrophil counts within 2 weeks in patients with hairy cell leukemia and neutropenia. This therapy may be a useful adjunct to definitive treatment of hairy cell leukemia with interferon or pentostatin.

Agranulocytosis↗

Kinetics and mechanisms of recombinant human granulocyte-colony stimulating factor-induced neutrophilia.

Recombinant human granulocyte colony stimulating factor (G-CSF) injected intravenously in rats causes an initial peripheral neutropenia between 3 and 15 minutes and a subsequent neutrophilia beginning at 0.5 hours, peaking between 12 and 24 hours, and subsiding to normal between 30 and 36 hours. A striking hypersegmentation of neutrophil nuclei is observed between 30 and 48 hours. The bone marrow at 4 and 12 hours exhibits an increase in number, mitoses, size, and cytoplasmic granulation of myeloblasts and promyelocytes but a decrease in mature neutrophils, demonstrating that G-CSF acts not only as a mitogen and growth factor for early cells in the myeloid series but also as a releasing factor for mature marrow neutrophils. The bone marrow at 48 hours contains slightly increased numbers of myelocytes and metamyelocytes and large numbers of hypersegmented neutrophils. Dexamethasone and gamma-interferon inhibit the magnitude of G-CSF-induced neutrophilia, suggesting that endogenous glucocorticosteroids and gamma-interferon, both which are released along with G-CSF in vivo during endotoxemia, may play a negative feedback role in the endogenous regulation of granulopoiesis. G-CSF may act in concert with other monokines such as tumor necrosis factor (TNF) and interleukin-1 (IL-1) to induce the changes in circulating numbers of leukocytes noted during endotoxemia.

Animals↗

HTLV x gene mutants exhibit novel transcriptional regulatory phenotypes.

The human T-cell leukemia viruses, HTLV-I and HTLV-II, contain a gene, termed x, with transcriptional regulatory function. The properties of the x proteins were analyzed by constructing mutant genes containing site-directed deletions and point mutations. The results demonstrate that the amino terminal 17 amino acids of the x protein constitute part of a functional domain that is critical for the transcriptional activating properties of the protein. Within this region, substitution of a leucine residue for a proline residue results in major changes in the trans-activation phenotype of the protein. The mutant HTLV-II x protein, though incapable of activating the HTLV-II long terminal repeat, will block trans-activation of the HTLV-II long terminal repeat by the wild-type protein. The altered phenotype of this mutant suggests a potential negative regulatory function of the x protein.

Deltaretrovirus↗

T-cell activation defect in common variable immunodeficiency: restoration by phorbol myristate acetate (PMA) or allogeneic macrophages.

Common variable immunodeficiency (CVI) represents a group of familial and sporadic diseases characterized by a range of B-cell, T-cell, and macrophage defects. A defect in T-cell activation, involving reduced proliferation and IL-2 production after stimulation with OKT3 antibody, has been described previously. In the present study we found that these defects could be corrected in vitro by adding phorbol myristate acetate (PMA) to OKT3-stimulated peripheral blood mononuclear cells (PBMC) of 14 patients with CVI. PBMC of 6 out of 7 patients with CVI studied also exhibited a profound defect in IL-2 receptor expression when incubated with OKT3 antibody. IL-2 receptor expression after stimulation with PMA alone was normal, indicating that the OKT3- but not the PMA-induced pathway of IL-2 receptor expression was defective. On the RNA level, the genes for IL-2 and IL-2 receptor were expressed after stimulation with OKT3 antibody. IL-2 and IL-2 receptor gene expression were normal, indicating a possible post-transcriptional defect. To investigate whether the defect in T-cell activation was at the macrophage or the T-cell level, we prepared adherent cells and monocyte-depleted T cells (E+) from 3 patients with CVI and from normal blood donors. Incubating CVI E+ cells with normal adherent cells resulted in normal proliferation and IL-2 production in the presence of OKT3, whereas incubation of normal E+ cells with adherent cells from patients with CVI under the same conditions showed reduced IL-2 production and proliferation, suggesting the macrophage as the origin of the failure in T-cell activation in the patients with CVI studied. Inhibition by macrophage-secreted prostaglandins was excluded by failure to correct the IL-2 production and proliferation defects in the presence of indomethacin.

Adult↗

Recombinant human TNF alpha stimulates production of granulocyte colony-stimulating factor.

Tumor necrosis factor alpha (TNF alpha) stimulates production of granulocyte colony-stimulating factor (G-CSF) protein and mRNA in fibroblast cells. In contrast, TNF beta is at least 1,000-fold less potent than TNF alpha in increasing levels of G-CSF and GM-CSF activity and mRNA. The fibroblasts produce G-CSF and GM-CSF mRNA in a coordinate fashion after exposure to TNF. The ability of TNF alpha to stimulate production of CSF in fibroblasts may be pivotal to regulation of hematopoiesis.

Adult↗

Comparison of the trans-activation capabilities of the human T-cell leukemia virus type I and II chi proteins.

The mechanism of cellular transformation by the human T-cell leukemia viruses (HTLVs) is thought to involve a novel retrovirus gene known as chi. The chi gene is essential for HTLV replication and acts by enhancing transcription from the viral long terminal repeat. By using the HTLV type I and II chi gene-coding regions inserted into a highly efficient expression vector, we directly compared the efficiencies of the two chi proteins to trans activate the HTLV type I and II long terminal repeats. We demonstrate that the two chi proteins have different patterns of trans activation. The patterns were highly reproducible in all mammalian cells tested. A different pattern of activation was observed in avian cells. These results suggest that the mechanism of trans activation involves specific cellular factors that are highly conserved throughout mammalian species but different in avian cells. Understanding the mechanism of trans activation by the chi gene product may provide insights into mechanisms of cellular transformation by HTLV.

Acetyltransferases↗

Rescue of anti-influenza A virus cytotoxic T-lymphocyte responses in chemotherapy-suppressed mice.

The administration of cyclophosphamide (50 to 100 mg/kg) at 48 to 72 h before removal of murine lung or spleen mononuclear cells for culture rendered DBA/2 mice incapable of generating an effective cytotoxic T-lymphocyte response to influenza A virus-infected cells. The cytotoxic T-lymphocyte precursor frequency to influenza A virus in lung and spleen cells from cyclophosphamide-treated mice was significantly decreased when compared with that of normal littermate controls. The low cytotoxic T-lymphocyte activity in the lungs and spleens of cyclophosphamide-treated mice could be partially restored in vitro by human interleukin 2.

Animals↗

Gene segments encoding transmembrane carboxyl termini of immunoglobulin gamma chains.

In cell lines producing IgM, secreted and membrane bound forms of immunoglobulin mu heavy chains are produced from two separate mu mRNAs that are identical except for alternative 3' coding sequences. We now show that cell lines producing IgG likewise contain two mRNA species for immunoglobulin gamma chains. The major, 1.7 kilobase (kb) species encodes secreted gamma chains. A less abundant species of 3-4 appears to encode membrane bound gamma chains, in that it contains an alternative 3' end encoded in separate exons 3' to the remainder of the gene. The first exon of this M gene segment has been identified in chromosomal gamma 1 and gamma 2b gene clones by its sequence homology with the corresponding exon in the mu gene. Like the mu M exon, it encodes a probable transmembrane polypeptide segment. The flanking DNA sequences show a patchwork pattern of homology between genes that suggests a checkered evolutionary history.

Amino Acid Sequence↗