Search PubMed⌕ Search

Biomedical subjects

V Barbu

Publications and source records attributed to V Barbu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Thrombocytopenia after bone marrow transplantation caused by a recipient origin Br(a) allo-antibody: presence of mixed chimerism 3 years after the graft without hematologic relapse.

We report a case of mild, clinically asymptomatic, immune thrombocytopenia after allogenic bone marrow transplantation (BMT) for chronic myeloid leukemia (CML) caused by the presence of a recipient-origin Br(a) antibody that recognized the donor platelets. Although the antibody titer decreased, it remained detectable more than 3 years after BMT. Chimerism studies were performed combining cytogenetics, blood cell phenotype studies, and genomic amplification of hypervariable sequences. Cytogenetic studies and molecular analysis of peripheral blood cells, purified B- and T-lymphocyte subpopulations, and bone marrow colonies showed the hematopoiesis to be of donor origin, but absorption-elution experiments with peripheral RBCs showed a small amount of recipient RBCs. The CML chimeric transcript was also detected by means of polymerase chain reaction on samples collected until day +867 post-BMT. This case shows that recipient-origin platelet alloantibodies can cause thrombocytopenia after BMT and that the persistence of small numbers of recipient cells (even leukemic) is not necessarily associated with hematologic relapse.

Adult↗
PubMed1994

Analysis of BCR/ABL transcripts in chronic myeloid patients by nested PCR using an immunoassay-like detection format.

We describe an 'immunoassay-like' detection format, based on the AMPLICIS technique for the routine detection of BCR/ABL transcripts in leukaemic patients. The AMPLICIS technique is characterized as a nested PCR coupled to solid phase isotopic or non-isotopic detection of PCR products. Comparison between this assay and a conventional PCR technique using Southern-blot analysis provided a good correlation between the two procedures. The assay, easier and faster than the conventional one, gives access to automation and therefore appears well suited for the routine screening of BCR/ABL chimaeric mRNAs.

Base Sequence↗
PubMed1994

Albumin messenger RNA as a marker of circulating hepatocytes in hepatocellular carcinoma.

BACKGROUND/AIMS: Hepatocellular carcinoma is one of the most frequent malignancies. Liver transplantation is theoretically the treatment of choice because it eliminates both the hepatocellular carcinoma and the cirrhosis. High frequency of relapse observed after liver transplantation may be explained by the existence of undetectable metastasis before transplantation. The aim of this study was to determine whether albumin messenger RNA (mRNA), a specifically hepatocyte-expressed gene, could be a marker of metastasis in hepatocellular carcinoma. METHODS: Albumin mRNA from circulating malignant hepatocytes was detected in the blood by reverse transcription followed by enzymatic amplification. RESULTS: Albumin mRNA was found in the blood of 3 patients with histologically proven metastatic hepatocellular carcinoma and in 9 of 21 patients with hepatocellular carcinoma and undetectable metastases, giving a percentage rate of 43, similar to the relapse rate following liver transplantation for hepatocellular carcinoma. None of the 8 patients with secondary liver cancer had detectable albumin mRNA. CONCLUSIONS: These results suggest that patients with hepatocellular carcinoma and no detectable albumin mRNA in the blood may be a subgroup with a low risk of relapse following liver transplantation.

Base Sequence↗
PubMed1994

[Oncogenic activation of p21(ras) and pp60(c-src) in human colonic Caco-2 cells decreases insulin receptor function and expression through protein kinase C-dependent and independent pathways].

In view of the potent mitogenic effect exerted by insulin in human colonic cells, we used Caco-2 cells transfected with an activated (Val12) human Ha-ras gene or the polyoma middle T (PyMT) oncogene, a constitutive activator of pp60c-src tyrosine kinase activity, to investigate the effect of oncogenic p21ras and PyMT/pp60c-src on insulin mitogenic signaling. As compared to vector control Caco-2 cells, both oncogene-transfected cells exhibited: 1) a lost of response to insulin's stimulatory effect on mitogen-activated protein (MAP) kinase activity and cell proliferation, both of which were constitutively increased; 2) a decrease in insulin receptor (IR) affinity and insulin-stimulated exogenous tyrosine kinase activity, which resulted, at least in part, from increased protein kinase C (PKC) activity (4), since both IR alterations were partially corrected by PKC down-regulation; and 3) a decrease in both insulin receptor mRNA level and insulin receptor number, which was independent of PKC since it persisted after PKC down-regulation. In conclusion, oncogenic p21ras and PyMT/pp60c-src abolished insulin mitogenic signaling in Caco-2 cells through mechanisms involving (i) constitutive activation of MAP kinase, and (ii) marked decreases in both insulin receptor function and expression which were mediated by PKC-dependent and PKC-independent pathways respectively. This is the first evidence that, when oncogenically activated, p21ras and pp60c-src not only exert a negative control on insulin receptor function but also repress insulin receptor gene expression in human colonic cells.

Carcinoma↗
PubMed1994

Autologous bone marrow transplantation in ALL: relapse linked to infusion of tumor cells with the back-up marrow.

A 41-year-old female patient with a pre-B ALL expressing 2 BCR/ABL transcripts e1/a2 and b2/a2 underwent autologous bone marrow transplantation (aBMT) with marrow grown in long-term culture (LTC) for consolidation of remission (CR). After failing to engraft on day 54 she received her back-up marrow. She engrafted by day 23 and developed a full-blown leukemic relapse 2 weeks later. She died from tumor progression 3 months after infusion of the backup marrow. Analysis of the BCR/ABL transcripts weakly positive at time of collection of the backup marrow, negative in the LTC marrow and in the patient after infusion of the LTC marrow, again positive from day 29 after infusion of the backup marrow until death, strongly suggests that infusion of residual tumor cells with the backup marrow contributed to the relapse.

Adult↗
PubMed1993

Interferon gamma is effective for BM purging in a patient with CML.

We report a case of Ph-positive CML where the BM was incubated for 24 h with 10(3) IU/ml IFN gamma and then cultured in liquid media for 4 weeks. After 24 h incubation, there was no differential sensitivity of CML CFU-GM to IFN gamma compared with untreated BM. Subsequent long-term culture (LTC) of the IFN gamma treated CML BM, however, demonstrated a 75% inhibition of production of CFU-GM from the second week onwards. Using PCR, we were able to demonstrate two types of BCR-ABL transcript in the diagnostic BM. After 4 weeks of LTC, the J(bcr b3/ABL II) RNA transcript persisted in the untreated BM, whereas neither BCR/ABL RNA transcripts were detected in the culture established with IFN gamma-treated CML BM. This study has two points of interest with the demonstration of (1) a possible antileukaemic effect of IFN gamma on the progenitors generated in the LTC system, and (2) the use of highly sensitive PCR technology to evaluate the effectiveness of IFN gamma to purge CML BM of Ph-positive cells.

Bone Marrow↗
PubMed1993

Polymerase chain reaction: a method for monitoring tumor cell purge by long-term culture in BCR/ABL positive acute lymphoblastic leukemia.

We report the successful purging of leukemia cells bearing the Philadelphia chromosome and BCR/ABL transcripts by long-term marrow culture (LTC), and subsequent grafting of the purged marrow in a case of refractory acute lymphoblastic leukemia. The efficiency of the purge was evaluated by polymerase chain reaction (PCR) for BCR/ABL transcripts. In two LTCs initiated in the blastic stage, we demonstrated the selective effect of three culture media (serum dependent, serum-free (SF) supplemented or not with IL3 and GM-CSF) on the proliferative potential of normal hematopoietic (CFU-GM/BFU-E) and leukemic progenitors (CFU-ALL). BCR/ABL positive cells disappeared after 3 to 4 weeks of culture. The addition of IL3 and GM-CSF to the SF medium enhanced the growth of CFU-GM/BFU-E and shortened the purging period. We therefore carried out a LTC in the presence of IL3 and GM-CSF with marrow harvested in morphological remission. BCR/ABL positivity was detected at the outset, although no leukemia cells could be identified. The BCR/ABL was no longer found by PCR in the 7 and 14 day LTCs. The patient, consolidated by high dose polychemotherapy and total body irradiation, was infused with the 14 day LTC. This study indicates that PCR is a useful and sensitive technique for monitoring tumor cell reduction after LTC prior to autografting.

Bone Marrow Purging↗
PubMed1992

Processing and characterization of the low density lipoprotein receptor in the human colonic carcinoma cell subclone HT29-18: a potential pathway for delivering therapeutic drugs and genes.

Low density lipoprotein (LDL) processing has been investigated in the subcloned human colonic carcinoma cell line HT29-18. LDL binding at 4 degrees C was a saturable process in relation to time and LDL concentration. The Kd for LDL binding was 11 micrograms/ml. ApoE-free HDL3 or acetylated LDL did not significantly compete with 125I-LDL binding, up to 500 micrograms/ml. 125I-LDL binding was decreased by 70% in HT29-18 cells preincubated for 24 hours in culture medium containing 100 micrograms/ml unlabelled LDL. Ligand blotting studies performed on HT29-18 homogenates using colloidal gold labelled LDL indicated the presence of one autoradiographic band corresponding to an apparent molecular weight of 130 kDa, which is consistent with the previously reported molecular weight of the LDL receptor in human fibroblasts. At 37 degrees C, 125I-LDL was actively internalized by HT29-18 cells and lysosomal degradation occurred as demonstrated by the inhibitory effect of chloroquine. LDL uptake and degradation by HT29-18 cells also resulted in a marked decrease in endogenous sterol synthesis. These data demonstrate that the HT29-18 human cancerous intestinal cells are able to specifically bind and internalize LDL, and that LDL processing results in down-regulation of sterol biosynthesis. Thus, intestinal epithelial cells possess specific LDL receptors that can be exploited to accomplish drug delivery and gene transfer via the receptor-mediated endocytosis pathway.

Colonic Neoplasms↗
PubMed1992

Detection of BCR/ABL translocation by polymerase chain reaction in leukemic progenitor cells (ALL-CFU) from patients with acute lymphoblastic leukemia (ALL).

In about 30% of cases, BCR/ABL transcripts are present in freshly isolated mononuclear cells from the bone marrow of patients with acute lymphoblastic leukemia (ALL) using the polymerase chain reaction (PCR) technique. We applied PCR to investigate the leukemic nature of ALL colony-forming unit (ALL-CFU) colonies grown in a clonogenic assay using a double feeder system. The high sensitivity of PCR enables us to detect 1 leukemic cell among 10(5) normal cells. Several controls were taken to assess contamination. In this report we studied three patients with ALL. In all of them, BCR/ABL transcripts were detected at initial diagnosis. We showed that the PCR technique could identify the leukemic nature of ALL-CFU progenitors. In addition, we demonstrated the nonleukemic nature of granulocyte-macrophage colony-forming unit (CFU-GM) and erythroid burst-forming unit (BFU-E) colonies using the same analysis. We conclude that the PCR technique is of great value in the identification of leukemic clones whenever specific molecular markers are present.

Autoradiography↗
PubMed1991

Serum-free liquid marrow culture in patients with acute lymphoblastic leukaemia: a potential application to purge marrow for autologous transplantation.

We have previously established a serum-free (SF) culture medium, which supports normal haemopoietic progenitor cell growth for at least 4 weeks as does conventional serum dependent (SD) medium. In the present study, we investigated the efficacy of such a defined SF liquid medium which sustained in vitro residual normal haemopoietic proliferation of marrow derived from ALL patients and which was detrimental for the leukaemic population. Evidence for a potential selective effect of SF culture was obtained by a leukaemic progenitor cell assay (ALL-CFU) and the detection of the bcr/abl translocation by polymerase chain reaction (PCR). In 13 experiments including 12 patients, morphological blast cells and ALL-CFU were dramatically reduced within 3 weeks of incubation in both SF and SD cultures. Likewise, in 5/5 experiments in SD and 2/5 experiments in SF conditions, leukaemic cells expressing the bcr/abl fusion gene disappeared within 3-4 weeks. In contrast, the absolute numbers of supernatant cells harvested weekly from SF and SD cultures were similar. No difference in CFU-GM production was detected for the two culture systems. Erythropoiesis in SF medium exhibited a slower decline than that found in SD. These results indicate that liquid marrow culture may selectively deplete leukaemic lymphoblastic cells and enable repopulation by residual normal haemopoietic cells. This technique may be useful to purge leukaemic cells for clinical autologous bone marrow transplantation in patients with ALL.

Adolescent↗
PubMed1991

Clinical value of PCR in diagnosis and follow-up of leukaemia and lymphoma: report of the third Workshop of the Molecular Biology/BMT study group.

The proceedings of the third workshop of the molecular biology/bone marrow transplantation (BMT) study group held in January 1991 in Verona, Italy. This workshop was convened to review progress in the application of molecular techniques to the diagnosis and follow-up of patients with chronic myeloid leukaemia (CML) as well as other haematologic malignancies. The results of polymerase chainreaction studies in 157 CML patients 1-90 months post BMT suggest that leukaemia is frequently detectable for the first 12 months but rarely detected thereafter except in patients known to have a high risk of relapse. In the acute leukaemias and lymphomas there is a rapidly increasing number of leukaemia-specific as well as clone-specific molecular markers now available for the detection of minimal disease. It may be possible to coordinate multi-center prospective studies to investigate the role of these markers in the diagnosis and follow-up of haematologic malignancies.

Bone Marrow Transplantation↗
PubMed1990

Immortalization and neoplastic transformation of fetal rat intestinal epithelial cells: morphological and cytogenetic analysis, (proto)oncogene expression and effect of gamma-interferon on cell growth.

The permanent SLC-11 and -41 intestinal epithelial cells respectively immortalized by the E1A and large T oncogenes and their clonal derivatives showed a cytogenetic heterogeneity characterized by a near diploidy in SLC-11 and -12 cells and a generalized polyploidy in SLC-41 and -44 cells. Persistence of chromosome translocations and trisomy 3 were observed. The expression of the E1A oncogene in immortalized SLC-11 cells is associated with a strong repression of c-fos transcription during the exponential growth, as compared to the resting phase or to control rat fetal intestinal epithelial cells. The transcription of c-myc was also reduced in SLC-11 cells, especially in confluent cells. A complex relationship between the levels and size of the c-fos, c-myc mRNAs and the expression of the E1A oncogene was therefore observed in SLC-11 cells. Immortalized SLC-11 and -41 cells showed a remarkable growth inhibition in response to recombinant rat gamma-IFN. Neoplastic transformation by activated human Ha-ras in SLC-12T and -44 T cells confer resistance to the antigrowth effects of IFN. The combination of culture conditions using defined medium, membrane matrix (laminin, collagen, proteoglycans) and intestinal mesenchyme revealed the persistence of the undifferentiated phenotype of the E1A, large T-immortalized and Ha-ras-transformed SLC cells in vitro or in the nude mice. In association with the intestinal chick endoderm, SLC-11 cells possess some inductive properties on the differentiation of villi projections arising from the chick endoderm in vivo. In contrast, SLC-41 cells were induced to differentiate in enterocyte-like cells by the intestinal chick mesenchyme. The immortalized and Ha-ras-transformed SLC cells therefore constitute new models in the sequential analysis of the molecular and genetic mechanisms involved in the proliferation, differentiation and oncogene-mediated neoplastic transformation in gut. Further attempts in SLC cell differentiation have to be accomplished using chemical inducers for prolonged periods of time, or by transfection of intestinal epithelial cells using temperature- or glucocorticoid-inducible vectors.

Animals↗
PubMed1990

Application of serum-free liquid bone marrow cultures to bone marrow purging for autologous bone marrow transplantation in acute lymphoblastic leukemia.

We have previously established a serum-free (SF) culture medium which allows normal haematopoietic progenitor cells to be maintained for at least 4 weeks as in the conventional serum dependent SD) medium. In the present study we investigated the efficiency of the SF liquid system to sustain normal residual haemopoiesis to the detriment of the leukemic population in patients with ALL. Probes for a potential selective effect were brought through leukemic progenitor cell assay (CFU-ALL) and the polymerase chain reaction (PCR) study of the bcr/abl translocation. In 13 experiments done in 12 patients, morphological blast cells and the ALL-CFU were dramatically reduced within 3 weeks of incubation in both SF and SD cultures. In 5/5 experiments in SD conditions and 2/5 experiments in SF conditions, leukemic cells expressing the bcr/abl fusion gene also disappeared within the same period. There was no difference in the CFU-GM production between SF and SD mediums. Erythropoiesis exhibited a slower decline in conditions SF, compared to the conditions SD. These results indicate that the liquid marrow culture may selectively deplete the leukemic lymphoblastic cells and enable repopulation by residual normal hemopoietic cells. It may be useful to purge leukemic cells for clinical autologous bone marrow transplantation in patients with ALL.

Bone Marrow Cells↗
PubMed1990

Mevalonate deprivation alters the induction of fos and myc by growth factors.

Besides cholesterol, mevalonate is the precursor of several isoprenoid compounds including the farnesyl moiety of isoprenylated proteins. Inhibition of mevalonate biosynthesis leads to a growth arrest that can be relieved by addition of mevalonate, but not of cholesterol. To get a better understanding of the mechanisms underlying this growth inhibition, we have investigated whether mevalonate derivatives are implicated in the early response to growth factors. Our results show that pretreatment of quiescent human fibroblasts with mevinolin, an HMG CoA reductase inhibitor, partially suppresses fos and myc mRNA accumulation in response to serum stimulation. This effect of mevalonate deprivation appears to be on the transcriptional regulation of fos and does not depend upon the nature of the initial events of signal transduction, since the same phenomenon was observed following EGF and TPA stimulation.

Blotting, Northern↗