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Biomedical subjects

G Tricot

Publications and source records attributed to G Tricot.

At least 127 records · Page 7Linked to original sources
PubMed1991

Some reasons for the lack of progress in the treatment of acute myelogenous leukemia: a review of three consecutive trials of the treatment of poor prognosis patients.

The failure of three consecutive treatment protocols to significantly increase the complete remission rate for poor prognosis newly diagnosed patients with acute myelocytic leukemia led to a detailed investigation of the causes of treatment failure. In the majority of cases treatment failure was attributable to "clinical resistance" to therapy. Upon close examination two types of "clinical resistance" were discernible: the failure of chemotherapy to produce adequate cytotoxic effects ("classical" drug resistance), and treatment failure attributed to the rapid regrowth of leukemia cells subsequent to the substantial killing of leukemia cells by cytotoxic therapy ("biological" resistance). Each form of resistance accounted for one-half of the treatment failures.

Aged↗
PubMed1991

Pregnancy-associated aplastic anemia--report of 3 cases.

3 patients with pregnancy-associated aplastic anemia are reported. Management throughout most of the pregnancy consisted of supportive care. In 2 patients an improvement in blood counts occurred after delivery and, in 1 of these, the pancytopenia recurred during a subsequent pregnancy. In 1 case no improvement occurred after delivery and the patient ultimately required an allogeneic bone marrow transplantation. The outcome of these 3 cases demonstrates that pregnancy-associated aplastic anemia can be managed successfully. The improvement that often occurs after delivery suggests a pathogenetic role for pregnancy in the development of this disease.

Adult↗
PubMed1991

Tiazofurin down-regulates expression of c-Ki-ras oncogene in a leukemic patient.

The increased activity in cancer cells of inosine 5'-monophosphate dehydrogenase (IMP DH, EC 1.1.1.205), the rate-limiting enzyme of de novo GTP biosynthesis, was suggested as a sensitive target for chemotherapy. Tiazofurin (NSC 286193), through its conversion to the active metabolite, thiazole-4-carboxamide adenine dinucleotide (TAD), is a strong inhibitor of IMP DH. In our clinical trial, tiazofurin caused return to the chronic phase in patients with chronic granulocytic leukemia in blast crisis (Tricot, G.; Jayaram, H.N.; Weber, G.; Hoffman, R. Tiazofurin: Biological effects and clinical uses. Int. J. Cell Cloning 8:161-170; 1990). In K562 human leukemic cells, tiazofurin down-regulated the expression of c-Ki-ras and c-myc oncogenes, which was followed by induced differentiation. We now report down-regulation by tiazofurin of the c-Ki-ras oncogene in a patient with chronic granulocytic leukemia in blast crisis. A single tiazofurin infusion (2,200 mg/m2) on days one and two decreased IMP dehydrogenase activity (the apparent t1/2 was 30 min), GTP concentration (the apparent t1/2 was 6 hr), and expression of ras (the apparent t1/2 was 8 hr) and c-myc (the apparent t1/2 was 38.5 hr) oncogenes in the leukemic cells. No further tiazofurin was given, because on days three and four the chemotherapeutic impact became evident in a tumor-lysis syndrome and the blast cells were cleared from the periphery by day five. The decrease in IMP DH activity, GTP concentration, and expression of c-Ki-ras oncogene were early markers of the successful chemotherapeutic impact of tiazofurin in a patient with chronic granulocytic leukemia in blast crisis.

Adenine Nucleotides↗
PubMed1991

High dose carboplatin/VP-16 plus ifosfamide with autologous bone marrow support in the treatment of refractory germ cell tumors.

We report seven patients with germ cell tumors which either recurred following a minimum of two regimens of platinum-based chemotherapy or were refractory to cisplatin. The patients were treated with one or two courses of high dose carboplatin (CBDCA) and etoposide (VP-16) plus ifosfamide (IFX) with mesna uroprotection and autologous bone marrow support. The doses given were CBDCA 500 mg/m2 every other day x 3 and VP-16 400 mg/m2 every other day x 3. IFX was given in a dose of 2 g/m2 daily x 5 days with mesna. The original intent of the protocol was to explore escalating doses of IFX, but excessive renal toxicity at the first dose level prevented escalation. Of the seven patients treated, four developed a marked decline in their renal function and three of the four required hemodialysis or hemofiltration. Six of seven patients treated had a decline in their serum markers indicating a response to therapy, but all have relapsed. Our conclusion is that while the combination of CBDCA/VP-16/IFX with ABMT is active in this group of patients, it is associated with excessive renal toxicity which is probably due to underlying renal dysfunction secondary to extensive prior cisplatin-based chemotherapy.

Adolescent↗
PubMed1990

Excessive zinc ingestion. A reversible cause of sideroblastic anemia and bone marrow depression.

Two patients with sideroblastic anemia secondary to zinc-induced copper deficiency absorbed excess zinc secondary to oral ingestion. The source of excess zinc was a zinc supplement in one case; in the other, ingested coins. In each case, the sideroblastic anemia was corrected promptly after removal of the source of excess zinc. These two cases emphasize the importance of recognizing this clinical entity, since the myelodysplastic features are completely reversible.

Adult↗
PubMed1990

Hematologic neoplasia associated with primary mediastinal germ-cell tumors.

Between September 1983 and December 1988, we observed 16 cases of hematologic neoplasia associated with mediastinal germ-cell tumors. Twenty-eight similar cases have been reported in the literature. A review of the clinical and cytogenetic details in these patients suggests that the hematologic neoplasia is not the result of cisplatin-based chemotherapy of the mediastinal germ-cell cancer. This syndrome was found only in patients with nonseminomatous mediastinal germ-cell tumors, particularly those with serologic or histologic evidence of yolk-sac elements. The two most common hematologic neoplasms seen in this syndrome were acute megakaryoblastic leukemia and malignant histiocytosis. Consistent cytogenetic abnormalities have not yet been identified, but the finding of the marker chromosome isochromosome (12p) in the mediastinal germ-cell tumor and associated leukemic blasts in one patient suggests that these tumors may arise from a common progenitor cell.

Adolescent↗
PubMed1990

Tiazofurin: biological effects and clinical uses.

Inosine 5'-phosphate dehydrogenase (IMPDH) activity is increased in all cancer cells. It is the rate-limiting enzyme of guanosine triphosphate (GTP) biosynthesis, and therefore, a sensitive target of chemotherapy. Tiazofurin selectively blocks IMPDH activity. Tiazofurin was found to have an antiproliferative effect on tumor cells in vitro and in the murine system. Based on these findings, Phase I trials were started elsewhere in patients with solid tumors, but were discontinued because of toxicity. In leukemic patients, we were able to demonstrate a good correlation between biochemical parameters (i.e., decline in IMPDH activity and GTP concentrations in blast cells) and clinical response. The most consistent responses to therapy were seen in patients with myeloid blast crisis of chronic myeloid leukemia. Severe toxicity was seen in the earlier patients in the study. However, better patient selection, limitation of treatment duration and earlier recognition and treatment of complications have now made it possible to administer tiazofurin without undue toxicity.

Antineoplastic Agents↗
PubMed1990

Spontaneous remission in myelodysplastic syndrome. A case report.

A patient with refractory anemia with excess blasts (RAEB) and pancytopenia is reported. He was red blood cell (RBC)-transfusion dependent. Karyotype analysis showed a complex cytogenetic abnormality consisting of loss of chromosome 7 and trisomy 8. Without cytotoxic treatment, his complete blood count (CBC) subsequently became normal. He is no longer transfusion dependent and repeat cytogenetic analyses are normal.

Chromosome Aberrations↗
PubMed1990

Inosine monophosphate dehydrogenase inhibitors. Probes for investigations of the functions of guanine nucleotide binding proteins in intact cells.

Taken together, the above reports indicate that the IMP dehydrogenase inhibitors are valuable probes for investigation of the biological functions of guanine nucleotides in intact cells. While these agents have minor effects on levels of other nucleotides and enzymes, non-specific effects can be monitored by addition of guanine or guanosine to provide substrates for the salvage pathway of guanine nucleotide synthesis. The most important question yet to be resolved in employing these agents is why incomplete depletion of intracellular guanine nucleotides results in such dramatic effects on G-protein function. Since the level of GTP in resting cells is approximately 0.5 mM, even a 90% reduction in GTP levels should leave enough nucleotide to adequately activate most known G-proteins, as the latter display high binding affinities for guanine nucleotides in cell free systems. Several explanations have been proposed to account for this disparity. Much of the intracellular guanine nucleotide may be bound or compartmentalized and therefore unable to interact with certain G-proteins. Possibly, G-proteins in the intracellular environment possess a much lower affinity for GTP that they do in cell free system. It may be to the cells' advantage that relatively minor fluctuations in levels of GTP result in pronounced alterations in the biological function of G-proteins as this effect may provide a physiologically important mechanism for the regulation of G-proteins in vivo. Further studies are necessary to clarify the mechanisms involved in the regulation of the biological function of G-proteins and oncogene products by guanine nucleotides in intact cells.

Animals↗
PubMed1990

Characteristics of engraftment after repeated autologous bone marrow transplantation.

The rate of engraftment after autologous bone marrow transplantation (ABMT) is extremely variable and largely unpredictable. To identify factors influencing engraftment, we studied 35 patients with refractory germ cell tumors undergoing high-dose chemotherapy with carboplatin (900-2000 mg/m2) and etoposide (1200 mg/m2) with bone marrow rescue. Prior to the initiation of chemotherapy, bone marrow sufficient for two marrow infusions was harvested (range 0.86-4.82 x 10(8) nucleated cells per kg). All 35 patients received half of the collected bone marrow 3 days after the last dose of chemotherapy; 23 responders received a second round of the same chemotherapy followed by infusion of the second half of the bone marrow. Eighteen patients could be compared for the two transplant episodes. The "rate of engraftment" was defined as the unweighted mean of four parameters: 1) the number of days until the absolute granulocyte count surpassed 0.2 x 10(9)/liter, 2) the number of days until the absolute granulocyte count surpassed 0.5 x 10(9)/liter, 3) the number of days until the last platelet transfusion, and 4) the number of days until the reticulocyte count surpassed 25 x 10(9)/liter. No significant correlation was found between rate of engraftment and such factors as the number of nucleated cells per kg infused, the dose of chemotherapy, extent of prior chemotherapy, tumor response to the high-dose chemotherapy, age of the patient, or the days of granulocytopenic fever (all p greater than 0.20). In contrast, a close correlation was found for the number of units of platelets (p = 0.005) and red blood cells (p = 0.006) transfused following each of the two transplants. There was no significant difference between rate of engraftment after first and second transplantation. Comparison of these data with the results obtained in reported ABMT with separate harvests suggests that the characteristics of the infused marrow determine the rate of engraftment after ABMT. This model of repeated transplantation could provide an important tool for assessing the therapeutic efficacy of hematopoietic growth factors.

Bone Marrow Transplantation↗
PubMed1990

Treatment of refractory lymphoma with high dose cytarabine, cyclophosphamide and either TBI or VP-16 followed by autologous bone marrow transplantation.

This study was designed to test the efficacy and toxicity of combining high-dose cytarabine (3 g/m2 every 12 h x 8 doses day -7 to day -4, total dose 24 g/m2), methyl prednisolone (0.5 mg/kg every 4 h day -7 to day -1), and cyclophosphamide (CY) (60 mg/kg day -3 and day -2) with either total body irradiation (TBI) (900 cGy in a single fraction on day -1) or VP-16 (600 mg/m2/days -7, -5, and -3) in patients not eligible for TBI secondary to prior radiotherapy. We treated 14 patients (eight male, six female) with either non-Hodgkin's lymphoma (n = 5) or Hodgkin's disease (n = 9). All patients had failed prior conventional chemotherapy (median two regimens range 1-5). Five patients were treated with TBI and nine with VP-16. There were eight complete remissions, two partial remissions, four were inevaluable for response due to early death. Overall survival is 21% (3/14) and relapse-free survival is 7% (1/14) with the sole disease-free survivor now 40 months from transplant. Very significantly, among patients receiving TBI, there were no survivors (median survival 24 days, range 17-330 days) and 4/5 had pulmonary complications. Median DLCO in these four patients was 61% (range 50-67) prior to transplant and none had an infectious etiology established by bronchoalveolar lavage. Median time to an absolute granulocyte count of 500 x 10(6)/l was 16 days (range 10-37 days) and to a platelet count of 20 x 10(9)/l was 12 days (range 7-22 days). In conclusion, the addition of high-dose cytarabine (24 g/m2) to CY and single-dose TBI or VP-16, while being very active, produced excessive pulmonary toxicity in this group of patients with lymphoma.

Adolescent↗
PubMed1989

Involvement of guanine nucleotides in superoxide release by fluoride-treated neutrophils. Implications for a role of a guanine nucleotide regulatory protein.

Previous studies demonstrating hydrolysis of phosphatidylinositol bisphosphate (PIP2) and generation of inositol phosphates in neutrophils exposed to 20.0 mM NaF provide indirect evidence that activation of phospholipase-associated guanine nucleotide regulatory protein, a guanine nucleotide binding protein which regulates the activation of a membrane inositol-specific phospholipase C, is an early event in the neutrophil stimulus-response pathway triggered by fluoride. Consistent with this hypothesis, exposure of a plasma membrane rich preparation isolated from 32P labeled neutrophils to 20.0 mM NaF resulted in hydrolysis of labeled PIP2. Levels of other phospholipids were not affected. Inositol bisphosphate and inositol trisphosphate were detected in extracts of neutrophil plasma membranes exposed to fluoride. To further explore the involvement of guanine nucleotides in functional responses of intact neutrophils triggered by fluoride, we preincubated cells with 2-beta-D-ribofuranosylthiazole-4-carboxamide (tiazofurin), a selective inhibitor of inosine monophosphate dehydrogenase, to diminish guanine nucleotide synthesis and then compared superoxide generation induced by FMLP, PMA, digitonin, and 20.0 mM NaF to intracellular levels of guanine nucleotides. Preincubation of neutrophils for 2.5 h at 37 degrees C with tiazofurin resulted in dose-dependent depletion of GTP and GDP. Maximal depletion of guanine nucleotides required relatively high levels of tiazofurin (200 to 400 microM) and resulted in a 55 to 60% reduction of GTP and GDP. The effects of tiazofurin on guanine nucleotides levels were not observed when neutrophils were preincubated at 4 degrees C. AT 37 degrees C, tiazofurin also decreased intracellular ATP and ADP levels but adenine nucleotide depletion was less pronounced than guanine nucleotide depletion for each concentration of tiazofurin used. When tiazofurin was removed by washing cells after incubation, adenine nucleotide quickly returned to preincubation values but guanine nucleotide levels remained depressed. Addition of exogenous guanosine (200 microM) prevented tiazofurin-dependent depletion of guanine nucleotides but had no influence on adenine nucleotide depletion. Superoxide released triggered by FMLP and F- was inhibited to an extent similar to that of guanine nucleotide depletion under different conditions of preincubation. Inhibition of superoxide release was not observed if cells were preincubated at 4 degrees C, was not rapidly reversible, and was not observed when guanosine was added with tiazofurin.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenine Nucleotides↗
PubMed1989

Effects of recombinant human colony stimulating factors (CSF) (granulocyte-macrophage CSF, granulocyte CSF, and CSF-1) on human monocyte/macrophage differentiation.

Purified recombinant human granulocyte-macrophage (rhuGM)-CSF, rhuG-CSF, and rhuCSF-1 were evaluated for their capacity to influence the differentiation of U-937 cells and normal human monocytes. The human U-937 cell line represents an early stage of monocytic differentiation. It was found that rhuGM-CSF and rhuG-CSF, but not rhuCSF-1, induced phenotypic changes consistent with monocyte/macrophage differentiation in U-937 cells. After 3 days of culture in the presence of either rhuGM-CSF or rhuG-CSF, a small but significant proportion of U-937 cells were able to reduce nitroblue tetrazolium. Nitroblue tetrazolium reduction, however, was maximally induced when rhuGM-CSF and rhuG-CSF were added in combination. These changes were accompanied by increased alpha-naphthyl acetate esterase activity, acquisition of macrophage morphology, Mo-1 Ag expression, and decreased cell proliferation. rhuGM-CSF alone also induced expression of the c-fms proto-oncogene (CSF-1 receptor) in U-937 cells and this expression was enhanced by the combination of rhuGM-CSF and rhuG-CSF. In cultured normal human peripheral blood monocytes, representing a late stage of maturation, rhuGM-CSF and rhuCSF-1 differentially increased Mo-1 and My-4 Ag expression, respectively, whereas rhuG-CSF was without effect. Our results suggest that the interaction of GM-CSF, G-CSF, and CSF-1 may play a fundamental role in the early and late stages of the human monocyte/macrophage differentiation process.

Antigens, Surface↗
PubMed1989

Differentiation-inducing effect of recombinant human tumor necrosis factor alpha and gamma-interferon in vitro on blast cells from patients with acute myeloid leukemia and myeloid blast crisis of chronic myeloid leukemia.

Tumor necrosis factor alpha (TNF-alpha) and gamma-interferon (IFN-gamma) have been shown to suppress clonogenic growth in cultures containing blast cells obtained from patients with acute myeloid leukemia. We report that recombinant human TNF-alpha and IFN-gamma are also able to induce functional and morphological maturation in fresh myeloid leukemic cells in vitro. Assessing suspension cultures containing cells from patients with acute myeloid leukemia (11 patients) or myeloid blast crisis of chronic myeloid leukemia (5 patients), it was found that recombinant human TNF-alpha and IFN-gamma significantly enhanced the number of cells reducing nitroblue tetrazolium, as compared to control cultures containing no cytokine (P less than 0.001 and P less than 0.001, respectively). Cells from responders showed alterations characteristic of monocyte/macrophage differentiation, adherence to plastic surfaces, development of positive staining for alpha-naphthyl acetate esterase, typical morphology, and expression of cell surface antigens detected by the monoclonal antibodies Mo-1, Mo-2, and My-4. Both cytokines decreased the number of viable cells, the number of blast cells, and the number of cluster-forming units in suspension culture, suggesting inhibitory actions on the growth capacity of leukemic cells. Compared to the maximum effects of either factor alone, the combination of recombinant human TNF-alpha and IFN-gamma significantly increased the extent of growth inhibition and cell adherence but did not result in further increases in nitroblue tetrazolium reduction. The presence of Auer rods in IFN-gamma or TNF-alpha differentiation-induced macrophages with cells from a patient with M5 acute myeloid leukemia demonstrates that these cytokines can induce differentiation of a leukemic clone in primary cells from patients with leukemia.

Adolescent↗
PubMed1989

Recombinant human colony stimulating factor-granulocyte/macrophage and -granulocyte, but not macrophage induce the development of a respiratory burst in primary human myeloid leukemic cells in vitro.

Respiratory burst develops in myeloid blast cells if they differentiate functionally along the monocytic or granulocytic lineage. Using the nitroblue tetrazolium (NBT) assay we studied the effects of recombinant human granulocyte/macrophage colony stimulating factor (rhuGM-CSF), rhuG-CSF and rhuM-CSF on development of respiratory burst activity in primary blast cells from patients with myeloid leukemia. Assessing suspension cultures containing cells from patients with acute myeloid leukemia (AML, n = 13) or myeloid-blast crisis (myBC) of chronic myeloid leukemia (CML, n = 5) it was found that the percentage of NBT positive cells was increased by at least 20% as compared to control cultures by rhuGM-CSF in 6/17 cases, by rhuG-CSF in 7/17 cases and by rhuM-CSF in 0/16 cases, representing in 'responders' a mean increase of 267% and 270% in the absolute number of NBT positive cells by rhuGM-CSF and rhuG-CSF, respectively. Morphological examination of cultured cells from 'responders', as compared to controls, showed decreased blast cell content but generally no evidence of terminal differentiation. The demonstration of Auer rods in NBT positive cells indicates that respiratory burst developed in a leukemic clone. These findings may be of physiological, pathophysiological and clinical relevance.

Cell Differentiation↗
PubMed1989

Dose-intensive chemotherapy in refractory germ cell cancer--a phase I/II trial of high-dose carboplatin and etoposide with autologous bone marrow transplantation.

Between September 1986 and March 1988, 33 patients with refractory germ cell cancer were entered on a phase I/II trial of two courses of high-dose carboplatin plus etoposide with autologous bone marrow support. All patients had extensive prior treatment and had either cisplatin-refractory disease (67%) defined as progression within 4 weeks of the last cisplatin dose or failed at least two cisplatin-based regimens (35%) including a cisplatin-ifosfamide salvage regimen. Patients received a fixed total dose of etoposide of 1,200 mg/m2 with each cycle. The carboplatin dose ranged from 900 mg/m2 to 2,000 mg/m2. Twenty of the 33 patients received the second cycle of therapy. Despite extensive prior therapy with cisplatin, neurotoxicity, nephrotoxicity, or hearing impairment with high-dose carboplatin and etoposide was unusual. The most common nonhematologic toxicity was moderate enterocolitis. The hematologic toxicity of this regimen was substantial at each dose level. All 53 courses were accompanied by granulocytopenic fevers. Seven of the 33 patients (21%) died from treatment. All of these deaths occurred during the granulocyte nadir, and five were related to documented sepsis. Overall, 14 of 32 patients (44%) evaluable for response obtained an objective response, including eight complete remissions. Four patients remain in complete remission, with three patients being continuously free of disease in excess of 1 year. Eight responders (including four complete remissions) had progressed while receiving cisplatin. We conclude that carboplatin and etoposide can be administered in combination at high dosages and this regimen may have curative potential for patients with germ cell tumors resistant to conventional-dose cisplatin-based therapies.

Adolescent↗