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M C Magli

Publications and source records attributed to M C Magli.

At least 55 records · Page 3Linked to original sources
PubMed1994

HOX gene expression in human small-cell lung cancers xenografted into nude mice.

Transcription factors are crucial to an understanding of the molecular basis of neoplasia. Homeobox-containing genes are a family of transcriptional regulators encoding DNA-binding homeodomains, involved in the control of normal development. Class-I human homeobox-containing genes (HOX genes) display a peculiar chromosomal organization, perhaps directly related to their function. Aberrant expression of homeobox-genes has been associated with both morphological abnormalities and oncogenesis. We have recently observed that alterations in HOX gene expression are detectable in kidney and colon cancer when compared to the corresponding normal organs. Here we have analyzed the expression of HOX genes in primary and metastatic human small-cell lung cancer (SCLC) xenografted in nude mice, in order to investigate whether HOX gene expression correlates with the histology and stage of SCLC progression. The results show that different SCLCs display differential patterns of HOX gene expression. Furthermore, in SCLC, the number of actively expressed HOX genes might be substantially lower in metastatic cancers than in primary tumors. The alteration in HOX gene expression in SCLCs mainly concerns the HOX B and C loci. This finding suggests that downregulation of HOX genes may play a role in small-cell lung cancer progression, possibly through their implication in tumor suppression.

Animals↗
PubMed1994

Sperm:oocyte ratios in an in vitro fertilization (IVF) program.

PURPOSE: During the past few years, many oocyte insemination techniques, including microinjection, have evolved in the treatment of male-factor infertility. This preliminary study was designed to evaluate whether microdroplet insemination could be considered a reliable technique, especially for semen samples with male-factor defects. The first objective was to assess fertilization rates obtained by inseminating sibling oocytes using both the conventional IVF and the microdroplet method (Group 1). The second objective was to evaluate subsequent embryo development and pregnancy rates resulting from microdroplet insemination, in addition to formulating adequate sperm:oocyte ratios for various semen categories (Group 2). Four semen categories were studied including fresh normal sperm, frozen/thawed normal sperm, and male-factor sperm with one defect and two or three defects. RESULTS: Group 1 consisted of 54 couples; no statistical significance was found in the fertilization rates between test tube and microdroplet insemination in all four semen categories. Based on these results, patients from Group 2 (48 couples) had their oocytes inseminated only in microdroplets with sperm:oocyte ratios ranging from 2000 to 10,000 motile sperm:1 oocyte. The average fertilization rate for male-factor sperm was 55%, with a 91% cleavage rate. CONCLUSION: Higher fertilization rates were observed in the lowest range of sperm:oocyte ratios (2000-4000:1) for male-factor sperm with one defect and in the highest range (8000-10,000:1) for male-factor sperm with two or three defects. Polyspermy occurred in only 0.4% of the oocytes inseminated. Microdroplet insemination is an alternative treatment for moderate to moderately severe male-factor infertility, establishing a bridge between conventional IVF and microinjection. With adequate sperm:oocyte ratios, this technique allows the natural selection process of fertilization in vitro to take place, without the high incidence of polyspermy or mechanical damage frequently observed in assisted fertilization techniques.

Adult↗
PubMed1994

Biological factors affecting subzonal sperm microinjection results.

One hundred and sixteen couples with severe male factor infertility underwent 139 subzonal sperm microinjection cycles. In total, 1343 oocytes were microinjected, resulting in a fertilization rate of 24%, followed by a cleavage rate of 65%. In 26% of the zygotes, fertilization was delayed and embryos derived from these zygotes demonstrated a poor capacity for further growth and implantation. In 102 of 139 cycles (73%) embryo transfer was performed, resulting in 9 pregnancies. This study followed the fate of injected oocytes and early embryo development to investigate biological factors that influence the results of subzonal injection.

Embryo Transfer↗
PubMed1993

Characteristic patterns of HOX gene expression in different types of human leukemia.

Homeobox-containing genes are a network of genes encoding DNA-binding proteins highly conserved throughout evolution. They are involved in the control of normal development as well as in the regulation of gene expression in adult differentiating systems, including hematopoiesis. Aberrant expression of homeobox-containing genes has recently been related to leukemic phenotype. Human homeobox-containing genes of the HOX family are organized into 4 large clusters. We have analyzed the expression of HOX genes in different types of human leukemia to investigate whether the physical organization of HOX loci reflects a regulatory hierarchy involved in the differentiation of hematopoietic cells or whether HOX gene expression might contribute to the leukemic phenotype. Our results show that HOX genes are coordinately regulated in blocks in myeloid cells whereas they appear to function as isolated genes in lymphoid cells. Six contiguous genes of the HOX2 locus, highly expressed in acute non-lymphocytic leukemia, are switched off in chronic myelogenous leukemia, suggesting that down-regulation of HOX2 genes might be required for cell maturation of the myeloid lineages. In contrast, a few scattered genes are active in lymphoid populations. These observations suggest that hematopoietic cells express a repertoire of HOX genes characteristic of a particular cell lineage at a specific stage of differentiation. The characteristic patterns of HOX gene expression may reflect the potentially important role that these genes play in cell lineage determination during both normal and leukemic hematopoiesis.

Cell Differentiation↗
PubMed1993

Expression of homeobox-containing genes in primary and metastatic colorectal cancer.

Homeobox genes are a network of genes encoding nuclear proteins functioning as transcriptional regulators. Human and murine homeobox genes of the HOX family are organised in four clusters on different chromosomes. Gene order within each cluster is highly conserved, perhaps in direct relation to their expression. Homeobox genes have recently been involved in normal development and oncogenesis. We have analysed HOX gene expression in normal human colon and in primary and metastatic colorectal carcinomas. The majority of HOX genes are active in normal adult colon and their overall expression pattern is characteristic of this organ. Furthermore, the expression of some HOX genes is identical in normal and neoplastic colon indicating that these genes may exert an organ-specific function. In contrast, other HOX genes exhibit altered expression in primary colon cancers and their hepatic metastases which may suggest an association with colon cancer progression.

Colon↗
PubMed1992

HOX gene expression in normal and neoplastic human kidney.

As a consequence of transformation, cancer cells generally lose some of their differentiative properties. Thus, alterations interfering with the genetic mechanisms required to maintain embryonic determination could lead to tumorigenesis. Homeobox genes are a network of genes encoding nuclear proteins containing DNA-binding homeodomains that are highly conserved throughout evolution. They are expressed in a stage-related fashion in the developing embryo and, in adult life, in normal tissues. In mice and humans, homeobox genes of the HOX family are organized in 4 clusters on different chromosomes which have presumably evolved by duplication of a primordial gene cluster. Strikingly, the order of genes within each cluster is also highly conserved throughout evolution, suggesting that the physical organization of HOX genes might be essential for their expression. Recent reports indicate that homeobox mutant mice display morphological abnormalities or show neoplastic alterations, and that growth factors can turn on homeobox genes. We have studied the expression of the Antennapedia-like HOX genes in normal human kidney and in renal carcinomas. The great majority of the HOX genes analyzed are expressed in a peculiar manner in normal kidney: blocks of genes, even entire HOX loci, are coordinately regulated. Alterations in HOX gene expression in renal carcinoma can be observed in 2 genes of the HOX-2 locus, HOX-2A and HOX-2E, which are actively expressed in normal kidney and silent in cancer biopsies. The HOX-3H gene is not expressed in normal kidney whereas the HOX-3H transcripts are present in renal carcinomas. Homeobox genes within the 4 HOX loci can be aligned on the basis of the maximal sequence homology of their homeodomains: this alignment defines 13 paralogous gene groups. In renal carcinomas, genes of group 10 (HOX-1D, 2F, 3E, 4B) display a marked difference in their transcript classes when compared to those of normal kidney. Our findings suggest an association between altered HOX gene expression and kidney cancer.

Carcinoma, Renal Cell↗
PubMed1991

Coordinate regulation of HOX genes in human hematopoietic cells.

Hematopoiesis is a continuous process in which precursor cells proliferate and differentiate throughout life. However, the molecular mechanisms that govern this process are not clearly defined. Homeobox-containing genes, encoding DNA-binding homeodomains, are a network of genes highly conserved throughout evolution. They are organized in clusters expressed in the developing embryo with a positional hierarchy. We have analyzed expression of the four human HOX loci in erythroleukemic, promyelocytic, and monocytic cell lines to investigate whether the physical organization of human HOX genes reflects a regulatory hierarchy involved in the differentiation process of hematopoietic cells. Our results demonstrate that cells representing various stages of hematopoietic differentiation display differential patterns of HOX gene expression and that HOX genes are coordinately switched on or off in blocks that may include entire loci. The entire HOX4 locus is silent in all lines analyzed and almost all the HOX2 genes are active in erythroleukemic cells and turned off in myeloid-restricted cells. Our observations provide information about the regulation of HOX genes and suggest that the coordinate regulation of these genes may play an important role in lineage determination during early steps of hematopoiesis.

Cell Line↗
PubMed1991

[Monoclonal antibodies and T-cell clones against HLA antigens: production and characterization].

The production and characterization of 21 monoclonal antibodies (MoAbs) resulting from the immunization of Balb/c mice with human lymphoblastoid cell lines is reported. Twelve MoAbs seem to be detecting an HLA polymorphic determinant. Four MoAbs are recognizing monomorphic Class I molecules and another MoAb detects HLA Class II molecules. These results were confirmed by ELISA, cytotoxicity, immunofluorescence and immunoprecipitation. Class and subclass of the MoAbs were assessed by Ouchterlony analysis. Twenty two T cell clones were additionally generated by limiting dilution of lymphocytes stimulated by allogeneic peripheral blood lymphocytes on mixed lymphocyte cultures. Five of these clones were characterized, testing each one for its ability to proliferate in response to a panel of lymphoblastoid cell lines. It was found that they detect the HLA-A9, A23, A29-31, Bw62 and DR7 specificities respectively. These results indicate that the generation of cellular monoclonal reagents is apparently more productive than the generation of murine MoAbs specific for polymorphic variants of HLA antigens.

Animals↗
PubMed1988

A T cell clone defining a common DP/DR determinant in strong linkage disequilibrium with HLA-A9.

Clone F-7 was generated by limiting dilution of lymphocytes stimulated by allogeneic PBL on MLC. Priming against the A23, Cw6, B45, DR7, DRw53, DQw2 haplotype was performed between two HLA haploidentical first degree relatives. The clone was tested for its ability to proliferate in response to a panel of 38 homozygous B lymphoblastoid cell lines plus three local T cell lines. It showed a pattern of reactivity corresponding to HLA-A9 specificity (r = 1) and presented a concomitant cytotoxic activity. Phenotypically, this clone consisted entirely of CD4 cells, as determined by indirect immunofluorescence. Its reactivity was completely blocked by anti-DR (GSP4.1, PL8, L243) and anti-DP (B7/21, PL15) Mo-Abs, whereas anti-DQ (1A3, TU22) and anti-class I (w6/32, BB7.7) Mo-Abs and anti-A9 antibodies did not inhibit its reactivity. These results may suggest that clone F-7 could recognize a DP specificity sharing common determinants with DR, which occurs in linkage disequilibrium with HLA-A9.

Antibodies, Monoclonal↗
PubMed1987

Modulation of gene expression in multiple hematopoietic cell lineages following retroviral vector gene transfer.

Retrovirus vectors offer a simple and highly efficient method for introducing new genes into mammalian cells. Here, we have examined the efficiency of gene transfer into hematopoietic cells with retrovirus vectors carrying the neomycin (neo) resistance gene expressed from different transcriptional regulatory regions. Direct infection of mouse bone marrow cells resulted in high efficiencies of gene transfer into a variety of myeloid progenitor cells, including pluripotent, erythroid, and granulocyte-macrophage colony-forming cells with all the vectors examined. However, the progeny derived from individual pluripotent progenitor cells infected with different vectors differed markedly in the proportion of G418-resistant progenitor cells, as judged by their ability to survive selection in the drug G418. This biological assay suggests that the highest level of expression was observed when the neo gene was expressed from constructs that contained the herpes thymidine kinase promoter rather than the viral long terminal repeat or the simian virus 40 early region promoter. In contrast, neo gene expression was highest in fibroblasts infected with the vector containing the simian virus 40 early region promoter. These results show that high and sustainable levels of gene expression in hematopoietic cells can be obtained with retrovirus vectors containing appropriate transcriptional regulatory regions.

Animals↗
PubMed1985

Introduction of a selectable gene into primitive stem cells capable of long-term reconstitution of the hemopoietic system of W/Wv mice.

We have used the random chromosomal integration sites of retrovirus vectors as unique clonal markers to analyze cell lineage relationships within the hemopoietic stem cell hierarchy. Using a high efficiency protocol for retrovirus-mediated gene transfer, anemic W/Wv mutant mice were reconstituted with bone marrow cells infected with a NEO vector. Analysis of the DNA from bone marrow, thymus, and spleen of these reconstituted W/Wv mice indicated insertion of the vector into primitive pluripotent stem cells capable of producing both myeloid and lymphoid progeny as well as into more committed stem cells apparently restricted to either the myeloid or lymphoid lineages. The neo gene was also expressed in these mice, as they contained a variety of G418 resistant in vitro colony-forming cells. These results demonstrate high-efficiency gene transfer and expression in primitive hemopoietic stem cells and provide a direct approach for analyzing the hemopoietic stem cell hierarchy.

Animals↗
PubMed1985

Insertion of a bacterial gene into the mouse germ line using an infectious retrovirus vector.

Using a Moloney leukemia virus vector containing the bacterial neo gene, we demonstrate that retrovirus vectors can be used to introduce genes into the mouse germ line. Infection of preimplantation embryos with the vector MLV-NEO.1 resulted in integration of neo sequences in approximately equal to 10% of the progeny mice. One of these animals, mouse F.2, contained approximately six MLV-NEO.1 proviruses at independent integration sites, each present at less than a single copy per cell. This mosaic mouse transmitted one of these proviruses to her offspring, producing a line of transgenic mice carrying a full-length, unrearranged MLV.NEO.1 provirus at a single chromosomal integration site. Mice homozygous at this MLV-NEO.1 locus have also been produced. No expression of the neo gene has been detected in the transgenic mice, either by screening of primary bone marrow or lung cells for resistance to G418 or by RNA transfer blot analysis of RNA from several tissues. In addition, the neo gene was found to be extensively methylated in the transgenic mice; however, treatment of primary cells with 5-azacytidine did not induce G418 resistance. The inactivity of the MLV-NEO.1 provirus in transgenic mice and potential means of eliciting neo expression under these conditions are discussed.

Animals↗
PubMed1985

Early hemopoietic progenitor cells: direct measurement of cell cycle status.

We have investigated the cell cycle status of murine hemopoietic progenitors using vital DNA staining and flow sorting. Suspended Balb/c bone marrow cells were stained with Hoechst 33342 dye and separated first on light scattering properties; this procedure allowed a 5-fold enrichment in progenitor cells. A second sorting based on DNA content indicated that 80% of these cells were in G0/G1 and 20% in S-G2 + M. When G0/G1 and S-G2 + M cells were assayed separately in methylcellulose cultures, or with the in vivo colony forming assay, the G0/G1 cells were shown to be markedly enriched in CFU-S, BFU-E, and GM-CFU as compared to S-G2 + M cells with the final recovery increased 20-fold. Comparison of different strains or age groups yielded results identical to those obtained with Balb/c with the exception of C57B1/6. In the latter strain only a 3-fold enrichment could be observed in the G0/G1 fraction. These results demonstrate that the majority of early hemopoietic progenitors are in the G0/G1 phase of the cell cycle.

Animals↗
PubMed1979

Early fluctuations of BFU-E pool size after transfusion or erythropoietin treatment.

The kinetics of erythroid burst-(BFU-E) and colony-forming units (CFU-E) have been evaluated in marrow and spleen of normal or polycythemic mice, respectively, after transfusion or administration or purified erythropoietin (Ep). Ep injection induces an early but temporary rise of BFU-E number, versus a later but more prolonged expansion of the CFU-E pool. Symmetric patterns are observed after transfusion, i.e., an early but transient depletion of the BFU-E population, versus a later but more persistent decrease of the CFU-E number. It is suggested that the size of the BFU-E compartment is Ep-dependent in the "early" phase after erythroid perturbation. Later on, however, compensatory mechanisms allow the BFU-E pool to "escape" from the early Ep influence, thus allowing its size to return to and stabilize in the near normal range. It is further suggested that the BFU-E may represent an early target cell of Ep stimulus.

Animals↗
PubMed1978

Role of the hypophysis in erythropoietin production during hypoxia.

Hypophysectomized or sham-operated male rats were exposed to hypoxia (0.42--0.40 or 0.37--0.35 atm for 6, 12, or 24 hr) applied 2 wk to 7 mo after surgery. Erythropoietin (Ep) levels in rat serum were evaluated on the basis of the exhypoxic polycythemic mouse assay. Ep activity evoked by hypoxia was significantly lower in hypophysectomized rats than in sham-operated controls. Progressive increase of the EP response to hypoxia correlated with extension of the time interval between hypophysectomy and hypoxia from 2 wk to 2--4 mo apparently mediated by the simultaneous inverse decline of red cell mass (RCM) values, i.e., of the "relative plethora" induced by a low O2 demand associated with relatively high RCM values. However, after 3--7 mo hypoxic Ep activity was still lower than in sham-operated controls. In these ablated animals the relative plethora became negligible or absent; accordingly, the Ep response apparently had reached plateau levels. These studies indicate that hypophysis (hypophyseal and target hormones, with the exception of estrogens) modulates Ep production under hypoxic conditions, possibly via a permissive enhancement of renal Ep activity.

Animals↗