Biomedical subjects

Jaime Ferrer

Publications and source records attributed to Jaime Ferrer.

6 recordsLinked to original sources

PubMed2006

Tuning the electrical conductivity of nanotube-encapsulated metallocene wires.

We analyze a new family of carbon nanotube-based molecular wires, formed by encapsulating metallocene molecules inside the nanotubes. Our simulations, which are based on a combination of nonequilibrium Green function techniques and density functional theory, indicate that these wires can be engineered to exhibit desirable magnetotransport effects for use in spintronics devices. The proposed structures should also be resilient to room-temperature fluctuations, and are expected to have a high yield.

Journal Article↗

PubMed2005

Towards molecular spintronics.

The ability to manipulate electron spin in organic molecular materials offers a new and extremely tantalizing route towards spin electronics, both from fundamental and technological points of view. This is mainly due to the unquestionable advantage of weak spin-orbit and hyperfine interactions in organic molecules, which leads to the possibility of preserving spin-coherence over times and distances much longer than in conventional metals or semiconductors. Here we demonstrate theoretically that organic spin valves, obtained by sandwiching an organic molecule between magnetic contacts, can show a large bias-dependent magnetoresistance and that this can be engineered by an appropriate choice of molecules and anchoring groups. Our results, obtained through a combination of state-of-the-art non-equilibrium transport methods and density functional theory, show that although the magnitude of the effect varies with the details of the molecule, large magnetoresistance can be found both in the tunnelling and the metallic limit.

Chemistry↗

PubMed2004

Anaplastic carcinoma of the thyroid with rhabdomyosarcomatous differentiation: a report of two cases.

Anaplastic carcinoma of the thyroid gland (ACT) is a highly malignant tumor that is almost invariably associated with a fatal outcome. It demonstrates a variety of peculiar histological features, with squamoid, giant cell and spindle cell growth patterns. The spindle cell variant of ACT is usually indistinguishable from a true sarcoma and it can simulate fibrosarcoma, malignant fibrous histiocytoma (MFH), hemangiopericytoma and angiosarcoma or rhabdomyosarcoma. Although a rhabdomyosarcomatous appearance has sometimes been mentioned in the literature, true skeletal muscle differentiation has never been consistently proved. We report two cases of ACT with rhabdomyosarcomatous differentiation, as demonstrated by means of immunohistochemistry and electron microscopy. Both cases disclosed a very similar histological appearance, with a main population of small, pleomorphic, round-to-oval cells arranged in a storiform pattern, admixed with scattered pleomorphic giant cells, an image similar to that of the usual type of MFH. Stains for epithelial markers showed only few, scattered, weakly positive cells. Thyroglobulin and calcitonin were negative in tumor cells in both cases. On the contrary, positivity to vimentin was strong and generalized. Immunomarkers of muscular differentiation showed a consistent positivity. At the ultrastructural level, the cells disclosed the same spindle and pleomorphic morphology, with large, bizarre nuclei and cytoplasm with abundant mitochondria, rough endoplasmic reticulum, secretory granules and lipid droplets. There were also cells with wide cytoplasm filled with filamentous material, either of actin or myosin, as well as Z-band material. In conclusion, the cases reported here show a clear-cut rhabdomyosarcomatous differentiation of ACT, confirmed both immunohistochemically and ultrastructurally, a feature not previously reported in the literature. These findings may contribute to the broadening of the differentiation spectrum of this unusual neoplasm.

Carcinoma↗

PubMed2003

Cytogenetic and molecular findings related to rhabdomyosarcoma. An analysis of seven cases.

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in childhood. Histologically, it is subdivided histologically into two main subtypes: alveolar (ARMS) and embryonal (ERMS). ARMS is characterized by t(2;13)(q35;q14) or its variant t(1;13)(p36;q14), which fuse PAX3 and PAX7, respectively, with FKHR to produce chimeric genes. ERMS is frequently associated with loss of heterozygosity of 11p15.5. We investigated seven RMS (three ARMS and four ERMS) by means of cytogenetic, fluorescence in situ hybridization, and molecular analyses, including the study of the main genes implicated in the G1- to S-phase cell cycle transition, and correlated these studies with pathologic findings and clinical outcome. All tumors showed clonal, numerical, and structural chromosomal abnormalities. Two ARMS had the t(2;13)(q35;q14) and the third a PAX7/FKHR fusion, a cryptic t(1;13)(p36;q14), undetected by cytogenetic techniques, but revealed by reverse transcriptase polymerase chain reaction. One ERMS showed a der(11)t(3;11)(p21;p15) as a sole structural anomaly. Gene amplification was seen in four tumors, as double minutes or in the form of homogeneously staining regions. Overexpression of MYCN oncogene was found in two ARMS; N-myc DNA probe detected oncogene amplification located on the double minutes of these cases. Analysis of the regulatory genes responsible for G1- to S-phase transition showed a homozygous deletion of the 9p21 locus genes in a spindle-cell ERMS.

Child↗

PubMed2003

Establishment and characterization of a continuous human chondrosarcoma cell line, ch-2879: comparative histologic and genetic studies with its tumor of origin.

Chondrosarcomas are malignant cartilage-forming tumors that represent the second most common malignant solid tumor of bone. These biologically poorly understood neoplasms vary considerably in clinical presentation and biologic behavior. Chemotherapy and radiation therapy are generally ineffective. Here we describe the establishment and characterization of a new human chondrosarcoma cell line named ch-2879, and we compare the cell line with its tumor of origin. The cell line was established from a recurrent grade 3 chondrosarcoma of the chest wall and characterized by growth kinetics and morphologic studies. Immunocytochemistry and RT-PCR were performed to examine the expression of cartilage-specific phenotypes. Genetic characterization was performed using cytogenetics, fluorescence in situ hybridization, flow cytometry, and molecular techniques for analysis of the genes implicated in cell cycle control, amplification of MDM2, CDK4, and Cyclin D1, and mutations in the p53 gene. ch-2879 cells were subcultured for more than 80 passages. They expressed vimentin, HNK-1, HBA-71, Ki-67, cyclin D1, Fli-1, S-100, p21, p27, and p53 and were negative for cytokeratin, EMA, p14, p16, MDM2, Rb, and c-erb-b2 antigens. Cytogenetically the recurrent tumor showed a hyperhaploid karyotype with clonal numerical and structural abnormalities. The sole structural abnormality was a chromosome derivative of a t(1;21) translocation. The cell line at passage 3 showed two populations: the hyperhaploid and an exactly duplicated, hypotriploid population. After the 18th passage, only the hypotriploid population was present. The cells expressed collagen 2. Molecular comparison of the primary and recurrent tumor evidenced an in vivo molecular change consisting of a deletion of 9p21 genes in the recurrence, probably caused by a selection process. Because of its gene expression profile, including expression of genes implicated in chondrogenesis in uncoated plastic dishes, this cell line may prove useful for cellular and molecular studies as well as studies of chondrosarcoma characterization and treatment.

Bone Neoplasms↗

PubMedDate not supplied

Diffuse type of giant-cell tumor of tendon sheath: an ultrastructural study of two cases with cytogenetic support.

Two cases of the diffuse type of giant-cell tumor of the tendon sheath (GCTTS) are described. Both tumors arose in the vicinity of large joints of the lower extremity, showing similar clinical and radiological features. Histologically, a proliferation of polygonal mononuclear cells was seen, together with osteoclastlike giant cells, foam cells, and siderophages. The tumors were poorly delineated, displaying an infiltrative pattern into the neighboring soft tissues. Immunohistochemically, strong expression of vimentin, neuron-specific enolase, A1-antitrypsin, and CD68 was found in both mono- and multinucleated tumor cells. At the ultrastructural level, mononuclear cells revealed a diverse morphology, displaying features of histiocytelike and fibroblastlike cells, with the former being more numerous. Scarce neurosecretorylike granules, made up of electrondense membrane-bound material, were found in the cytoplasm of the mononuclear cells. Cytogenetic analysis of one case shows the presence of a clonal population with 47 chromosomes and two different translocations, t(2;3) and der(8) t(8;12). Present findings provide further support regarding the neoplasic nature of this tumoral entity.

Adult↗