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Biomedical subjects

I Larripa

Publications and source records attributed to I Larripa.

At least 19 recordsLinked to original sources
PubMed2003

A new animal model for human undifferentiated thyroid carcinoma.

An animal model of undifferentiated thyroid carcinoma (UTC), which may be useful for studying tumorigenesis and response to new therapies, is described. The UTC human cell line ARO was implanted into the back of the nude mice. The histology, induction of metastasis, and biokinetics of in vivo and in vitro growth, as well as cytogenetic and molecular aspects were studied. The tumor showed extensive viability with high mitotic activity. At 117 days, the tumors reached a size of 1,700 mm(3) and showed a central necrotic portion with a thin layer of viable cells. When the number of passages in the mouse increased the growth rate decreased. The cytogenetic and molecular studies did not show differences between the original line and the sublines that could explain this phenotypic change. Moreover, the original ARO cell line and its sublines showed a complex clonal karyotype including structural alterations with deletions and translocations involving chromosomes 5, 7, 8, 9p, 11p, 17q 19p, and 20q that were consistent with earlier reported data in UTC. This work provides an animal model of UTC pheno- and genotypically similar to the original human tumor, which may be useful for exploring new therapeutic modalities.

Animals↗
PubMed2001

Cryptic t(4;11) encoding MLL-AF4 due to insertion of 5' MLL sequences in chromosome 4.

The t(4;11) translocation is the cytogenetic hallmark of a subset of acute lymphoblastic leukemias characterized by pro-B immunophenotype and a dismal prognosis. This translocation fuses the MLL gene on chromosome band 11q23 and the AF4 gene on 4q21, resulting in the expression of fusion transcripts from both translocated chromosomes. The MLL-AF4 chimeric transcript is thought to mediate the leukemic transformation. The MLL genomic disruption detected by Southern blot and the RT-PCR for the MLL-AF4 chimeric transcript expression are molecular evidence of this chromosomal translocation. However, similar molecular rearrangements have also been identified in cases without the cytogenetic t(4;11). We report a 30-year-old patient with high risk ALL, a normal karyotype, and molecular evidence of MLL-AF4 fusion. Using a double color FISH assay with MLL specific PAC probes, a cryptic t(4;11) due to insertion of 5' MLL sequences in chromosome 4q21 was demonstrated. Consequently the MLL-AF4 was encoded by der(4). This insertion mechanism precludes the genomic recombination of AF4-MLL and supports the crucial role played by MLL-AF4 in leukemogenesis. The findings of our case, along with others, show the importance of complementing the karyotype with molecular and FISH techniques.

Adult↗
PubMed2000

In vitro inhibition of murine hematopoietic progenitors and stromal cells by vinorelbine.

Hematopoietic progenitor colony assays were used to establish the effects of the vinca alkaloid vinorelbine (VRB) on murine bone marrow. The in vitro growth of colony-forming units-granulocyte/macrophage (CFU-GM), burst forming units-erythroid (BFU-E) and colony-forming units-mix (CFU-mix) was dose-dependently inhibited by VRB. The highest dose assayed (0.02 microg/ml) suppressed all of the different progenitor cells by 100%. A comparison of the dose-response curves showed that CFU-GM, BFU-E, and CFU-mix exhibited similar-patterns of sensitivity to the cytotoxic action of VRB. Long-term bone marrow cultures have provided a valuable in vitro model for studying the role of the microenvironment of bone marrow. Cellularity of stromal layers was reduced with increasing doses of VRB. The appearance of these layers was altered minimally with the lowest dose used; a gradual loss of cellularity was seen in cultures exposed to 0.05 and 0.075 microg/ml; and a marked loss at the dose of 0.1 microg/ml. Our results show that VRB has an important effect on hematopoietic progenitors at the highest dose tested, while the stromal cells were not affected at a similar dose (0.025 microg/ml), suggesting that the stroma is more resistant to this drug.

Animals↗
PubMed2000

Intron 22 factor VIII gene inversions in Argentine families with severe haemophilia A.

Intron 22 factor VIII gene inversion (Inv22) is the most common mutation causing severe haemophilia A (SHA). We studied Inv22 in 34 SHA affected families by Southern blotting. Data from the familial history of the disease and the inhibitor status were also included. We found Inv22 in 41 % of SHA Argentine families (35 % with type 1 and 6 % with type 2), in close agreement with previously reported series. No significant correlation between the inheritance (familiar or sporadic disease) and the presence of inversions was found. Our population showed 24 % of families included at least one hemophiliac with inhibitor. In families positive for Inv22, 29 % of patients developed inhibitor but this increased frequency was not statistically significant. In conclusion, analysis of Inv22 in SHA patients should be used as a first line method because it provides useful and secure information for carrier detection and prenatal diagnosis in a high percentage of cases.

Argentina↗
PubMed2000

[Antisense oligonucleotides increase the apoptotic effect of idarubicin in K-562 cell line].

The cell line K-562, which carries bcr/abl rearrangement of type b3a2 is resistant to apoptosis induced by topoisomerase II inhibitors. K-562 cells were treated with complexes of cationic liposomes (DMRIE-DOPE and Dcchol-DOPE) and antisense oligonucleotides (AS-ODNs) directed against the b3a2 type of bcr/abl mRNA and non sense oligonucleotides (NS-ODNs), in a 3:1 lipid/DNA ratio during 72 hours, then they were incubated for a further 24 hours with idarubicin (IDA), 0.5 microgram/ml, to induce apoptosis. It was evaluated by morphology to the microscope of fluorescence. Cells treated with the complexes DMRIE-DOPE and Dcchol/DOPE with the specific AS-ODN showed a higher apoptosis percentage induced by IDA (mean +/- SD: 14.74 +/- 2.07 and 20.43 +/- 4.58, respectively) compared with controls not treated with ODNs (mean +/- SD: 8.08 +/- 0.82); (p < 0.05). These data indicate that the AS-ODNs directed against the b3a2 type of bcr-abl mRNA renders the cell line K-562 sensitive to IDA at the mentioned concentration.

Antibiotics, Antineoplastic↗
PubMed2000

Bcl-2 molecular analysis in paraffin-embedded biopsies from diffuse large B-cell lymphomas.

Translocation t(14; 18) has been observed in 50-85% of follicular and in 30% of diffuse non-Hodgkin lymphomas. About half of follicle center lymphoma (FCL) undergo histological conversion at relapse to more aggressive diffuse large B-cell lymphoma (DLBCL). This report correlates the molecular bcl-2/IgH rearrangement by PCR and Bcl-2 immunohistochemical (IHC) expression in a series of high grade DLBCLs with and without FCL remnant. Twenty-three paraffin-embedded lymph nodes from DLBCL patients were analyzed. Eleven patients showed FCL remnant (Group A) and 12, did not (Group B). Single PCR from paraffin extracted DNA followed by Southern transfer of products, hybridisation with internal oligoprobes for the MBR/JH and MCR/JH bcl-2 rearrangements and IHC analysis of Bcl-2 expression, were performed. PCR analysis was positive in 34.8% of patients. Bcl-2/IgH gene rearrangements were observed in 8 (34%) cases and 7 (30%) showed Bcl-2 expression on large noncleaved B-cells (centroblasts). All patients from Group A showed IHC positive reaction on FCL remnant (small cleaved cells) but only 2 (18%) were positive in DLBCL areas, suggesting either the loss of the bcl-2 expression on the transformed lymphoma, or, alternatively, the development of a second disease when the first lymphoma transforms. Group B patients showed a clear correlation between PCR and IHC studies. Our results suggest a similar frequency of t(14; 18) in DLBCLs to that reported in Europe and USA series. The discordance observed between PCR and IHC, particularly in Group A, points out the necessity to perform both studies in order to detect bcl-2 gene involvement in DLBCLs.

Adult↗
PubMed1999

Chromosomal aberrations in human lymphocytes exposed in vitro to enrofloxacin and ciprofloxacin.

Chromosomal aberrations were evaluated in cultures of human peripheral lymphocytes from eight healthy donors, exposed to the antimicrobial enrofloxacin (EFX) or to its major metabolite ciprofloxacin (CFX). In both treatments cultures revealed an increase in the chromosomal aberration level, detected as chromatid and chromosome breaks and gaps. Control cultures analysis revealed 3.6 +/- 0.6 chromosomal aberrations per 100 cells while treated cultures exhibited 8.3 +/- 0.8 and 9.6 +/- 1.2 aberrations at 5 and 50 microg/ml of EFX respectively. In CFX treated cultures it was found 5.6 +/- 1.3 and 7.7 +/- 3.5 aberrations/100 cells at 5 and 25 microg/ml antimicrobial concentration. These results suggested a genotoxic effect of EFX and CFX in the system used (P < 0.001). A reduction in the mitotic index and fuzzy metaphases were observed at 50 microg/ml of CFX, indicating a cytotoxic effect produced by this antimicrobial.

Adult↗
PubMed1999

Comparison of the aneugenic effect of vinorelbine and vincristine in cultured human lymphocytes.

Vinca alkaloids are used clinically against a variety of hematological and solid tumors. These compounds interact with tubulin subunits to prevent microtubule assembly, inducing abnormal chromosome segregation in dividing cells and causing aneuploidy. The vinca alkaloid vincristine sulfate (VCR) and the semisynthetic analog vinorelbine (VRB) were studied by analysis of micronuclei (MN) in cultured human lymphocytes using the cytokinesis block method. Furthermore, fluorescence in situ hybridization with a human alphoid satellite pancentromeric DNA probe was used to detect centromeres in isolated MN of VRB- or VCR-treated lymphocytes. At all the doses tested, both chemicals induced a significant increase in MN frequencies in binucleated (BN) cells (P < 0.001). The maximal effect was reached at a dose of 0.50 microgram/ml. At this dose, VRB produced an approximately 5-fold increase with respect to the control frequency of MN, while with VCR, this frequency increased 10-fold. Both drugs produced a slowing of the cell cycle, causing a decrease in the percentage of BN cells. This effect was lower with VRB. The percentages of centromere-positive MN were 89.79 and 87.60% in VRB- and VCR-treated cultures, respectively (control 27.03%). The high percentage of positive-signals in treated cultures (P < 0.001) indicates that the MN contained whole chromosomes. Our results confirm the aneugenic mode of action of these chemicals, VRB having less genetic effect.

Adult↗
PubMed1998

Spontaneous breakage and fragile site expression in chronic lymphocytic leukemia.

It has been suggested that genetic predisposition to cancer might be related to spontaneous chromosome instability or to fragile site expression. Therefore, spontaneous breakage and fragile sites were analyzed in nine untreated chronic lymphocytic leukemia (CLL) patients to determine their relation to cancer rearrangements. Five cases presented spontaneous gaps and breaks with a random distribution of breakpoints. In cultures treated with fluorodeoxyuridine or aphidicolin, 29 specific bands could be defined as fragile sites. A significant clustering of these sites was found with known common fragile sites (c-fra) and cancer breakpoints described in the literature. Most of these cancer breakpoints were involved in structural abnormalities associated with CLL (p < 0.00001). These data suggest that the expression of specific fragile sites might be related to structural chromosomal aberrations in CLL.

Aged↗
PubMed1998

Cytogenetic characterization of an extra structurally abnormal chromosome associated with severe mental retardation: inv dup (15) (q13).

We have studied an extra structually abnormal chromosome (ESAC) in a 13 years old boy with profound mental, psychomotor and speech retardation, behavioral problems, seizures and abnormal electroencephalogram. The examination of the bisatellited ESAC with chromosome banding demonstrated that the karyotype was: 47, XY, +inv dup (15) (pter-->q13::q13-->pter). The cytogenetic characterization of the inv dup (15) is reported with special emphasis on the usefulness of DA/DAPI staining when G-banding is sequentially performed to discard possible heteromorphisms in DA/DAPI positive chromosomes, and the importance of Ag-NOR heteromorphisms to ascertain the maternal origin of the inv dup (15). A U-type exchange between two non-sister chromatids is proposed as its mechanism of formation. The clinical features of the case were consistent with those previously reported in similar cases.

Adolescent↗
PubMed1998

The human breast cancer cell line IIB-BR-G has amplified c-myc and c-fos oncogenes in vitro and is spontaneously metastatic in vivo.

IIB-BR-G is an undifferentiated, highly heterogeneous, hormone receptor negative human breast cancer cell line previously established in our laboratory from a patient's primary tumor. An in vitro growing cell line (IIB-BR-G) and a xenotransplanted tumor growing in nude mice (IIB-BR-G(NUDE)) were derived. To further characterize these systems, immunocytochemical analysis was performed for differentiation antigens (PEM 200 kDa, CEA, NCA 90 kDa), blood-group related antigens (Le(x), sTn), oncogenes and tumor suppressor gene products (Her-2/neu protein, p53), metastasis-related cathepsin D and CD63/5.01 Ag, and the chemokine monocyte chemotactic protein 1 (MCP-1). Expression of markers was heterogeneous in these different systems. Previously reported karyotypic analysis has shown extensive chromosomal alterations including double min. Searching for oncogene amplification, we detected augmented copy number of c-myc and c-fos, the last one with two rearranged fragments. No amplification was found for c-erbB-2 in the cell line or in IIB-BR-G(NUDE), although this oncogene was amplified in the patient's primary tumor DNA. The differences observed between the patient's tumor, the cell line and the IIB-BR-G(NUDE) tumors are probably due to clonal expansion of cell variants not present in the original tumor. Electron microscopy of IIB-BR-G growing cells revealed epithelial characteristics with abundant dense granules, presumably secretory, distributed all over the cytoplasm and great nuclear pleomorphism. In vitro, IIB-BR-G cells showed a significant number of invading cells by Matrigel assay. After nearly 40 sequential subcutaneous passages of the original xenograft through nude mice, 80% of recipients developed spontaneous metastases, primarily to the lung and lymph nodes. Since this experimental model allowed to analyze changes produced in cancer cells from the primary tumor during adaptation to in vitro and in vivo growth, our results provide novel insights on the behaviour of hormone independent metastatic breast cancer.

Animals↗
PubMed1997

Vinorelbine: cell cycle kinetics and differential sensitivity of human lymphocyte subpopulations.

Antiproliferative activity induced by vinorelbine (VRB) was studied in whole blood cultures (WBC) and in lymphocyte subpopulations evaluated by the MAC (morphology-antibody-chromosome) method. In WBC a significant delay in cell cycle kinetics in VRB-treated cultures compared with controls (P < 0.001) was observed. The highest dose (1.0 microg/ml) arrested all cells at the first metaphase. Both WBC and isolated lymphocyte cultures showed a significant increase in the mitotic index (MI) in VRB-treated cultures compared with controls (P < 0.001). Moreover, a significant increase in the MI was found in VRB-treated CD4 cells compared with VRB-treated CD8 (P < 0.01) and B-lymphocytes (P < 0.001).

Adult↗
PubMed1997

Mitotic arrest and anaphase aberrations induced by vinorelbine in hamster cells in vitro.

Aneugenic effects of the Vinca alkaloid vinorelbine (VRB) were evaluated in vitro, measuring sister chromatid exchanges (SCE), cell proliferation kinetics and anaphase telophase aberrations in Chinese hamster ovary (CHO) cells. The highest dose of VRB (0.50 microg/ml) arrested cells at the first metaphase. An increase in abnormal anaphases was seen at 0.05-0.50 microg/ml of VRB, containing chiefly lagging chromosomes and multipolar spindles. No increase in SCE was found. These results indicate that VRB does not directly damage DNA, but acts on spindle microtubules, altering chromosome movement and causing aneuploidy.

Anaphase↗
PubMed1996

Chromosome instability in untreated adult celiac disease patients.

Spontaneous chromosome aberrations (CAs) and induced fragile sites (FSs) were analysed in 12 untreated adult coeliac disease (CD) patients and 8 healthy controls. Blood lymphocytes from each individual were cultured for 72 h at 37 degrees C in F-10 medium with 5% fetal calf serum and 0.1 ml phytohemagglutinine. FSs were induced by FudR (10 micrograms/ml, 24 h before harvesting) and caffeine (2.2 mM. 6 h before harvest). Spontaneous CAs and FSs were analysed on 30-50 Giemsa-stained and G-banded metaphases. The mean frequencies of spontaneous CAs (abnormal cells, gaps/cell and breaks/cell) of CD patients (0.24 +/- 0.02, 0.21 +/- 0.02 and 0.13 +/- 0.02, respectively) were significantly higher than those of controls (0.04 +/- 0.01, 0.02 +/- 0.01 and 0.02 +/- 0.01, respectively) (p < 0.001). Fourteen spontaneous CAs and 5 FSs specific for CD patients presented a strong coincidence (70%) with bands involved in T- and B-cell malignant lymphoma rearrangements. These findings suggest that CD has chromosome instability affecting specific points that could be related to the high prevalence of malignancies in this disorder.

Adolescent↗
PubMed1996

[Participation of fragile sites in cancer].

Structural and numerical chromosomal abnormalities are frequent findings in neoplastic cells. The origin of structural rearrangements is probably due to the existence of specific labile areas on human chromosomes. These areas, named fragile sites (FS), are prone to chromosomal breakage and rearrangements, playing an important role in the first steps of carcinogenesis. The classification of FS, the mechanisms involved in FS induction and their biological significance, specially their relationship with cancer development, are discussed.

Chromosome Fragile Sites↗
PubMed1995

Molecular study of the interferon genes in chronic myeloid leukemia.

The interferons alpha, beta, and w (IFNA, IFNB, IFNW), are a family of genes that have been mapped on the short arm of chromosome 9 (9p21-22). Deletions of genetic material on 9p are frequently observed in hematological diseases, particularly in lymphoid neoplasias. In this paper we have performed the molecular studies of IFNA and IFNB genes in chronic myeloid leukemia (CML) in order to determine if the deletions of these genes are prevalent in this pathology. Forty CML patients, Philadelphia positive or with BCR/ABL rearrangement, were studied at diagnosis. The analysis of IFNA and IFNB genes was performed by Southern and dot blot techniques. Homozygous or hemizygous deletions of IFNA and IFNB genes could not be detected, indicating that deletions of these genes would not be present or would be a very infrequent event in the chronic phase of the CML patients.

Adult↗