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Biomedical subjects

F Prada

Publications and source records attributed to F Prada.

18 recordsLinked to original sources
PubMed2006

Intradiploic frontal epidermoid cyst in a patient with repeated head injuries: is there a causative relationship?

Epidermoid cysts are rare disontogenetic tumoral lesions in the cranial compartment (1% of all intracranial tumors) and are usually located in relation to the cranial sutures; the intradiploic location is the less frequent. We report a clinical case in which the post-traumatic etiology of a frontal intradiploic epidermoid is considered. The histological findings revealed the presence of an epidermoid tumor associated with a typical foreign body inflammatory reaction, after repeated head traumas at the site of the tumour. This is the first case in whom the association between this tumoral lesion and a tissue inflammatory reaction due to foreign bodies is demonstrated.

Adult↗
PubMed2006

A photometric redshift of z = 6.39 +/- 0.12 for GRB 050904.

Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z approximately 20, and therefore to be powerful probes of the early Universe. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event identified. Here we report the discovery of the bright near-infrared afterglow of GRB 050904 (ref. 4). From our measurements of the near-infrared afterglow, and our failure to detect the optical afterglow, we determine the photometric redshift of the burst to be z = 6.39 - 0.12 + 0.11 (refs 5-7). Subsequently, it was measured spectroscopically to be z = 6.29 +/- 0.01, in agreement with our photometric estimate. These results demonstrate that GRBs can be used to trace the star formation, metallicity, and reionization histories of the early Universe.

Journal Article↗
PubMed2006

Skin gene therapy for acquired and inherited disorders.

The rapid advances associated with the Human Genome Project combined with the development of proteomics technology set the bases to face the challenge of human gene therapy. Different strategies must be evaluated based on the genetic defect to be corrected. Therefore, the re-expression of the normal counterpart should be sufficient to reverse phenotype in single-gene inherited disorders. A growing number of candidate diseases are being evaluated since the ADA deficiency was selected for the first approved human gene therapy trial (Blaese et al., 1995). To cite some of them: sickle cell anemia, hemophilia, inherited immune deficiencies, hyper-cholesterolemia and cystic fibrosis. The approach does not seem to be so straightforward when a polygenic disorder is going to be treated. Many human traits like diabetes, hypertension, inflammatory diseases and cancer, appear to be due to the combined action of several genes and environment. For instance, several wizard gene therapy strategies have recently been proposed for cancer treatment, including the stimulation of the immune system of the patient (Xue et al., 2005), the targeting of particular signalling pathways to selectively kill cancer cells (Westphal and Melchner, 2002) and the modulation of the interactions with the stroma and the vasculature (Liotta, 2001; Liotta and Kohn, 2001).

Animals↗
PubMed2004

Dark matter annihilation in the milky way galaxy: effects of baryonic compression.

If the dark matter (DM), which is considered to constitute most of the mass of galaxies, is made of supersymmetric particles, the central region of our Galaxy should emit gamma rays produced by their annihilation. We use detailed models of the Milky Way to make accurate estimates of continuum gamma-ray fluxes. We argue that the most important effect, which was previously neglected, is the compression of the dark matter due to the infall of baryons to the galactic center: it boosts the expected signal by a factor 1000. To illustrate this effect, we computed the expected gamma fluxes in the minimal supergravity scenario. Our models predict that the signal could be detected at high confidence levels by imaging atmospheric C erenkov telescopes assuming that neutralinos make up most of the DM in the Universe.

Journal Article↗
PubMed2002

Vertebral arterio-venous fistula presenting with intracranial hemorrhage.

Vertebral arteriovenous fistulas are rare lesions consisting of an abnormal shunt between the extracranial vertebral artery and the neighboring veins. The authors present a case of post-surgical high-flow left vertebral arteriovenous fistula presenting with intracranial hemorrhage. The patient underwent endovascular balloon occlusion of the fistula: after endovascular treatment a reduction of the flow was evident but the patient presented neurological deterioration related the occurrence of intraventricular-subarachnoid hemorrhage. Intracranial hemorrhage is a potential manifestation of high-flow vertebral AVF and a possible complication of endovascular fistula balloon occlusion. Direct endovascular occlusion of the vertebral artery may be primarily considered in selected cases.

Arteriovenous Fistula↗
PubMed2001

The retinoid fenretinide inhibits proliferation and downregulates cyclooxygenase-2 gene expression in human colon adenocarcinoma cell lines.

Fenretinide [N-(4-Hydroxyphenyl)retinamide, 4-HPR] (10(-10)-10(-6) M) treatment of HT-29 human colon cancer cells for 24-72 h significantly inhibited their growth. Using HCT-15 cells, 4-HPR had limited inhibitory effects on cell proliferation over the same concentration range and time period. The inhibitory effects of 4-HPR on cell growth in HT-29 cells were markedly reduced in the presence of exogenously added prostaglandins (PGs), suggesting a possible role for inhibition of PG synthesis as a mechanism for 4-HPR's antiproliferative effects. Inhibition of PGE(2) production was caused by 4-HPR in a concentration-dependent manner and decreased COX-2 but not COX-1 mRNA levels; this is the first indication that 4-HPR selectively inhibits COX-2 gene expression. Our findings suggest a possible mechanism for the chemopreventive and anti-proliferative effects of 4-HPR.

Adenocarcinoma↗
PubMed1999

Spatiotemporal gradients of differentiation of chick retina types I and II cholinergic cells: identification of a common postmitotic cell population.

The chick retina has three types of cholinergic amacrine cells. We have found that Types I and II differentiate from a common population of postmitotic cells temporarily located in the inner plexiform layer (IPL cells). Golgi staining and immunocytochemistry for choline acetyltransferase (ChAT) and gamma-aminobutyric acid (GABA) were used to trace the development and fate of IPL cells. Transformation of the shape of IPL cells into those typical of both conventional amacrine cells and those displaced to the ganglion cell layer are seen. All IPL cells are doubly immunoreactive, for ChAT and GABA, from the time they appear as a cell population within the inner plexiform layer (IPL) until their separation into the two amacrine cell populations. Polarization and early stages of shape differentiation of both types occur while they are in the IPL, starting in the dorsocentral area in the temporal retina and spreading to the rest of the retina. Three spatial gradients of differentiation are observed: from central-to-peripheral, dorsal-to-ventral, and temporal-to-nasal retina. Our findings suggest that the fate of both types of cells in the chick is determined locally, whereas their postmitotic precursors are within the IPL. The presence of GABA and acetylcholine in both types of amacrine cells at early stages of their morphogenesis, well before they have synaptic interactions, suggests a morphogenetic role for these molecules in inner retinal differentiation.

Acetylcholine↗
PubMed1997

Monocyte phagolysosomal fusion in children born to human immunodeficiency virus-infected mothers.

BACKGROUND: Previously we demonstrated that monocyte phagolysosomal fusion is impaired in chronic HIV infection in adult patients. METHODS: We studied the phagolysosomal fusion of peripheral blood monocytes from 45 children vertically infected with HIV, 38 noninfected infants born to HIV-positive mothers and 14 children born to HIV-seronegative women, by a cytomorphologic method in which acridine orange is used as a fusion marker. RESULTS: The mean percentages of phagolysosomal fusion +/-SD were 42 +/- 16.1 for HIV-positive children, 55.3 +/- 15.5 for HIV-negative infants born to HIV-infected mothers and 58.2 +/- 12.7 for normal controls. Monocyte phagolysosomal fusion of HIV-infected children was significantly decreased in comparison to noninfected and normal infants (P < 0.001), while there was no difference between the two latter groups. Phagolysosomal fusion impairment in HIV-infected infants inversely correlated with age (r = -0.4527; P < 0.002) and directly correlated with CD4+ T cell counts (r = 0.393; P = 0.03). Moreover, phagolysosomal fusion strongly correlated with clinical manifestations; this function was significantly impaired in moderately and severely symptomatic HIV-infected children with respect to those who remained asymptomatic or mildly symptomatic (P < 0.05). CONCLUSIONS: Our results suggest that monocyte function in HIV-infected children progressively deteriorates, closely related to the severity of the clinical symptoms.

CD4 Lymphocyte Count↗
PubMed1996

Recombinant human immunodeficiency virus type 1 (HIV-1) Tat protein inhibits phagolysosomal fusion in human peripheral blood monocytes.

The effect of recombinant HIV-1 Tat protein on different functions of peripheral blood monocytes, such as candidacidal activity and phagolysosomal fusion, was evaluated. HIV-1 Tat protein caused a significant impairment of phagolysosomal fusion at 100 ng/ml (p = 0.018). The inhibitory effect of Tat on phagolysosomal fusion was blocked by the addition of 1 microgram/ml monoclonal anti-Tat antibody. Candidacidal activity of peripheral monocytes was not altered by HIV-1 Tat protein at the concentration of 1 microgram/ml. These results indicate the HIV-1 Tat protein can affect the monocyte microbicidal mechanisms at the phagolysosomal fusion step with little or not effect upon the lytic activity.

Antimetabolites↗
PubMed1994

Immunological identity of the two different molecular mass constitutive subunits of liver arginase.

A detailed understanding of the regulatory mechanisms of arginase in the cell will depend on the clarification of the origin of the two different molecular mass subunits and on the arrangements of them to constitute the native enzyme. Here, we show the immunological recognition of the 39.5 and 37.0 kDa subunits of arginase by antibodies against both subunits. We also find that the subunit stoichiometry (39.5 kDa: 37.0 kDa) present in purified arginase preparations as well as in fresh isolated microsomes and cytoplasm corresponds to 3:1, indicating high prevalence of a constant arrangement of the constitutive subunits of arginase. These findings represent evidence for a limited posttranscriptional or posttranslational modification of only a fraction of the synthesized arginase in liver.

Animals↗
PubMed1981

Developmental study of axon formation in the horizontal neurons of the retina of the chick embryo.

Among the types of horizontal cells of the avian retina, one has been described that has an axon terminating in a typical structure. The present study analyses the histogenesis of this axon whose initial outgrowth occurs on day 14 of incubation (HH-40). The axon terminal is first detectable, towards day 15 of incubation (HH-41), in the form of a varicose thickening possessing short filopodia. The formation of the axon and the growth of the axon terminal is coincident with a retraction of the perikaryal process. The axon usually originates from one of the principal dendrites and in these stages shows short and fine filopodia throughout its length. From day 16 onwards (synaptic) spines may be distinguished, both in the dendritic field and on the axon terminal. The growth of the axon, in the phase when the axon terminal still has not formed, may exhibit deflections and deviations in its course, the possible cause and mechanism of which are discussed.

Animals↗
PubMed1981

Oil droplets in the chameleon (Chamaeleo chamaeleo) retina.

The cones of the chameleon retina have, in the scleral portion of their inner segment, an oil drop whose morphology is similar in all the photoreceptors possessing this droplet. The irregularities in the membrane surrounding the lipid matrix show close relationships with the surrounding mitochondria.

Animals↗