Biomedical subjects

Rocío Arranz

Publications and source records attributed to Rocío Arranz.

6 recordsLinked to original sources

PubMed2006

Bioinorganic transformations of liver iron deposits observed by tissue magnetic characterisation in a rat model.

The magnetic properties and the ultrastructure, with special emphasis on the nanometric range, of liver tissues in an iron overload rat model have been investigated. The tissues of the animals, sacrificed at different times after a single iron dextran injection, have been characterised by magnetic AC susceptibility measurements together with transmission electron microscopy (TEM) and selected area electron diffraction (SAED) as helping techniques. It has been observed that few days after the iron administration the liver contains at least two iron species: (i) akaganéite nanoparticles, coming from iron dextran and (ii) ferrihydrite nanoparticles corresponding to ferritin. The magnetic susceptibility of the tissues depends not only on the elemental iron content but also on its distribution among chemical species, and varies in a remarkable regular manner as a function of the elapsed time since the iron administration. The results are of relevance with respect to non-invasive techniques for liver iron determination, directly or indirectly based on the magnetic susceptibility of the tissues, as biomagnetic liver susceptometry (BLS) and magnetic resonance (MRI) image treatment.

Animals↗

PubMed2005

Aggregation phenomena on the ternary ionic-nonionic surfactant system: didodecyldimethylammonium bromide/octyl-beta-D-glucopyranoside/water. Mixed microaggregates, vesicles, and micelles.

The formation of a variety of mixed colloidal aggregates has been investigated on a ternary ionic-nonionic system constituted by (i) a double-chain cationic surfactant with a 12-carbon atom hydrophobic tail, didodecyldimethylammonium bromide (di-C(12)DMAB), (ii) a nonionic single-chain surfactant, octyl-beta-D-glucopyranoside (OBG), and (iii) water. The study has been carried out by means of conductivity, zeta-potential, transmission electron microscopy (TEM), and cryogenic transmission electron microscopy (cryo-TEM) experiments on the highly diluted, very diluted, and moderately diluted regions. The formation of mixed microaggregates, prior to the appearance of mixed vesicles, has been undoubtly confirmed by conductivity, TEM, and zeta-potential results. The concentrations at which these mixed colloidal aggregates form, i.e., the mixed critical microaggregate concentration (CAC), the mixed critical vesicle concentration (CVC), and the mixed critical micelle concentration (CMC), have been determined from conductivity data, while the zeta-potential experiments allow for the characterization of the aggregate/solution interface. The shape and size of the microaggregates and vesicles have been evaluated from TEM and cryo-TEM micrographs, respectively. All of the experimental evidence has been also analyzed in terms of the theoretical packing parameter, P.

Cryoelectron Microscopy↗

PubMed2005

Loss of E-cadherin mediated cell-cell adhesion as an early trigger of apoptosis induced by photodynamic treatment.

Photodynamic treatment with different photosensitizers (PSs) can result in the specific induction of apoptosis in many cell types. It is commonly accepted that this apoptotic response depends on the mitochondrial accumulation of the PS. Accumulation in other cellular organelles, such as lysosomes or the Golgi complex, and subsequent photodamage resulting in an apoptotic process has been also described. However, the role played by cell adhesion in apoptosis induced in epithelial cells after photodynamic treatment is not well characterized. Here, we have used a murine keratinocyte line, showing a strong dependence on E-cadherin for cell-cell adhesion and survival, to analyze the relevance of this adhesion complex in the context of zinc(II)-phthalocyanine (ZnPc) photodynamic treatment. We report that under apoptotic conditions, ZnPc phototreatment induces a rapid disorganization of the E-cadherin mediated cell-cell adhesion, which largely preceded both the detachment of cells from the substrate, via beta-1 integrins and the induction of apoptotic mitochondrial markers. Therefore, the alteration in E-cadherin, alpha- and beta-catenins adhesion proteins preceded the release of cytochrome c (cyt c) from mitochondria to the cytosol and the activation of caspase 3. In addition, blocking E-cadherin function with a specific antibody (Decma-1) induced apoptosis in this cell system. These results strongly suggest that the E-cadherin adhesion complex could be the primary target of ZnPc phototreatment, and that loss of E-cadherin mediated cell adhesion after early photodamage triggers an apoptotic response.

Animals↗

PubMed2005

Virus factories: associations of cell organelles for viral replication and morphogenesis.

Genome replication and assembly of viruses often takes place in specific intracellular compartments where viral components concentrate, thereby increasing the efficiency of the processes. For a number of viruses the formation of 'factories' has been described, which consist of perinuclear or cytoplasmic foci that mostly exclude host proteins and organelles but recruit specific cell organelles, building a unique structure. The formation of the viral factory involves a number of complex interactions and signalling events between viral and cell factors. Mitochondria, cytoplasmic membranes and cytoskeletal components frequently participate in the formation of viral factories, supplying basic and common needs for key steps in the viral replication cycle.

Animals↗

PubMed2004

Mixed vesicle formation on a ternary surfactant system: didodecyldimethylammonium bromide/dodecylethyldimethylammonium bromide/water.

The formation of mixed aggregates has been investigated on a ternary system consisting of two cationic surfactants with similar polar heads and two and/or one 12 carbon atom hydrophobic tail, respectively, didodecyldimethylammonium bromide and dodecylethyldimethylammonium bromide and water. The study has been carried out by means of conductivity, zeta potential, and cryogenic transmission electronic microscopy (cryo-TEM) experiments on the very diluted region. A variety of mixed aggregates, microaggregates, vesicles, and micelles has been found, depending on system composition and total surfactant concentration. Mixed critical microaggregate concentration and mixed critical vesicle concentration have been determined from conductivity data. Furthermore, zeta potential and cryo-TEM experiments allow for the characterization of the aggregates/solution interface and of the shape and size of the aggregates. This experimental evidence has also been analyzed in terms of the theoretical packing parameter, P.

Electric Conductivity↗

PubMedDate not supplied

Impact of chronic hepatitis C on HIV-1 disease progression.

BACKGROUND: Although there is clear evidence of an accelerated progression of liver fibrosis in HIV-positive patients with chronic hepatitis C virus (HCV) infection, it is unclear whether HCV infection may influence HIV-1 disease progression. We have analyzed the impact of HCV on CD4 counts and plasma HIV RNA in a large group of HIV-positive individuals. METHOD: Epidemiological data, CD4 counts, and plasma HIV RNA values were recorded from 902 consecutive HIV-1-positive persons who attended our institution since 1998. RESULTS: HCV infection was documented (antibodies and/or HCV RNA) in 72% of the total study population. The higher rates were seen among intravenous drug users (97%) compared to other groups (17% in homosexual men, 23% in patients who acquired HIV heterosexually). In a cross-sectional analysis performed at the first trimester of 2000, the mean CD4 count was lower among HCV-positive than among HCV-negative individuals (518 +/- 282 cells/microL vs. 620 +/- 302 cells/microL; p <.001). The mean plasma HIV RNA was 11,188 +/- 55,301 copies/mL in HCV-positive persons versus 6,352 +/- 32,152 copies/mL in HCV-negative persons (p =.03). Undetectable plasma HIV RNA (<50 copies/mL) was recognized in 54% of HCV-positive persons versus 64% of HCV negative persons (p =.04); a similar proportion of patients in each group was on antiretroviral therapy (90% vs. 93%) or HAART (86% vs. 89%). When comparing data from 1998 and 2000, the CD4 count increased an average of 53 cells/microL (11%) in HCV-positive persons versus 111 (19%) in HIV-negative persons during this 2-year interval (p <.05). Plasma HIV RNA on average declined 606 copies/mL (5%) in HCV-positive persons versus 5,788 copies/mL (54%) in HCV-negative persons (p <.05). A significant association between HCV infection and CD4 counts was recognized in the multivariate analysis, which was independent of gender, age, plasma HIV RNA, use of HAART, and adherence to therapy. In contrast, no significant effect of HCV on HIV RNA was found. CONCLUSION: Hepatitis C may be associated with a poor immunologic outcome in HIV-infected persons. This worst influence is not explained by a lower rate of antiretroviral therapy among HCV-positive persons nor a much poorer drug adherence in this population. Therefore, hepatitis C may act as a direct cofactor for HIV disease progression. If so, treatment of chronic hepatitis C might indirectly benefit HIV disease.

Adult↗