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Angel Alonso

Publications and source records attributed to Angel Alonso.

42 records · Page 3Linked to original sources
PubMed2002

Nup88 (karyoporin) in human malignant neoplasms and dysplasias: correlations of immunostaining of tissue sections, cytologic smears, and immunoblot analysis.

Nuclear pore complexes (NPCs) are elaborate macromolecular structures that regulate the bidirectional nucleocytoplasmic traffic system. In vertebrate cells, NPCs include a family of 50 to 100 proteins termed nucleoporins (Nups). The 88-kD Nup has been found to be linked in a dynamic subcomplex with the oncogenic CAN/Nup214. Applying a polyclonal antiserum to Nup88 on paraffin sections, we found that it immunoreacts with numerous malignant neoplasms. All carcinomas reacted irrespective of site, type, or degree of differentiation; often, high-grade carcinomas stained more strongly and extensively. Some sarcomas (e.g., fibrosarcomas, leiomyosarcomas, liposarcomas, and rhabdomyosarcomas) reacted intensely; melanomas, gliomas, mesotheliomas, and malignant lymphomas also stained. In situ carcinomas of the colon, stomach, breast, and prostate stained convincingly, as did in situ melanomas; some samples of fetal tissues also reacted. Cytologic smears of some of the aforementioned tumors also stained. In selected samples, enhanced immunostaining of tissue sections and cytologic smears correlated strongly and consistently with immunoblot data. Immunoblots of the same tumors with antibodies to 2 other Nups (Nup214 and Nup153) showed no comparable enhancement. Therefore, it seems that in some malignant tumors, Nup88 overexpression is not parallelled by an overexpression of other Nups. Benign tumors, hyperplasias, and normal tissues showed weak and sporadic staining or absence of staining; immunoblots of the same samples yielded weak signals. Occasional highly proliferative hyperplastic-reactive processes showed focal staining. Thus, our correlative histologic, cytologic, and molecular data indicate that Nup88 may be viewed as a potentially useful, broadly based histodiagnostic and molecular marker of many malignancies and premalignant dysplasias, and further suggest that in some malignant tumors, Nup88 may be selectively overexpressed as compared with other Nups. Thus, we propose that Nup88 be designated as karyoporin.

Biomarkers, Tumor↗
PubMed2002

Fine gating properties of channels responsible for persistent sodium current generation in entorhinal cortex neurons.

The gating properties of channels responsible for the generation of persistent Na(+) current (I(NaP)) in entorhinal cortex layer II principal neurons were investigated by performing cell-attached, patch-clamp experiments in acutely isolated cells. Voltage-gated Na(+)-channel activity was routinely elicited by applying 500-ms depolarizing test pulses positive to -60 mV from a holding potential of -100 mV. The channel activity underlying I(NaP) consisted of prolonged and frequently delayed bursts during which repetitive openings were separated by short closings. The mean duration of openings within bursts was strongly voltage dependent, and increased by e times per every approximately 12 mV of depolarization. On the other hand, intraburst closed times showed no major voltage dependence. The mean duration of burst events was also relatively voltage insensitive. The analysis of burst-duration frequency distribution returned two major, relatively voltage-independent time constants of approximately 28 and approximately 190 ms. The probability of burst openings to occur also appeared largely voltage independent. Because of the above "persistent" Na(+)-channel properties, the voltage dependence of the conductance underlying whole-cell I(NaP) turned out to be largely the consequence of the pronounced voltage dependence of intraburst open times. On the other hand, some kinetic properties of the macroscopic I(NaP), and in particular the fast and intermediate I(NaP)-decay components observed during step depolarizations, were found to largely reflect mean burst duration of the underlying channel openings. A further I(NaP) decay process, namely slow inactivation, was paralleled instead by a progressive increase of interburst closed times during the application of long-lasting (i.e., 20 s) depolarizing pulses. In addition, long-lasting depolarizations also promoted a channel gating modality characterized by shorter burst durations than normally seen using 500-ms test pulses, with a predominant burst-duration time constant of approximately 5-6 ms. The above data, therefore, provide a detailed picture of the single-channel bases of I(NaP) voltage-dependent and kinetic properties in entorhinal cortex layer II neurons.

Animals↗
PubMed2002

The human papillomavirus type 16 E5 protein impairs TRAIL- and FasL-mediated apoptosis in HaCaT cells by different mechanisms.

The effect of the human papillomavirus type 16 (HPV-16) E5 protein on apoptosis was investigated by using the polyclonal HaCaT-cell lines stably transfected either with E5 (HaCaT/E5) or the empty vector (HaCaT/pMSG) as reference. Apoptosis was triggered either by Fas ligand (FasL) or by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and was monitored by detection of cleavage of procaspase-8 and procaspase-3, as well as their substrate poly(ADP-ribose) polymerase (PARP). In contrast to the HaCaT/pMSG control cells we found that apoptosis induced by either of the two ligands is strongly suppressed in the E5-expressing keratinocytes. Fas expression is reduced by about a factor of two in HaCaT/E5 cells, which could be part of the mechanisms that protect the cells from FasL-induced apoptosis. For the TRAIL receptors, no such downregulation was observed. Here, E5 impairs the formation of the death-inducing signaling complex triggered by TRAIL. Apparently, E5 employs different mechanisms to inhibit death receptor signaling. This effect is not restricted to HaCaT/E5 cells since we found that the mouse fibroblast cell line A31-E5 is protected from TRAIL-induced apoptosis, as well but not the E5-lacking control cells A31-Neo. However, no such protection was observed upon FasL-induced apoptosis. Presumably, some of the antiapoptotic mechanisms employed by E5 of the human pathogenic HPV-16 are cell type specific. We propose that inhibition of ligand-mediated apoptosis in human keratinocytes is a primary function of the HPV-16 E5 protein needed to prevent apoptosis at early stages of viral infection.

Animals↗
PubMed2002

Serine proteinases with gelatinolytic activity in an Aspergillus fumigatus allergenic extract.

The presence of proteolytic activity in Aspergillus fumigatus (Af) extract was analyzed in polyacrylamide gelatine containing gels at different pHs. The gelatinolytic pattern showed three major activities (180, 70, and 34 kDa bands) over a broad pH range (pH 4-8). All bands showed maximum activity at pH 8, and the activity declined at lower pH, showing no activity at pH 2. The susceptibility of the proteolytic activity to protease inhibitors confirmed that the fungal extract contained serine proteinases, and one of them, the 34 kDa band, showed a chymotrypsin-like proteinase. The immunochemical fungal extract properties were studied by western blot, and the samples were run in the presence or absence of denaturing and reducing (DTT) conditions. Two protein bands located at approximately 180 and 84 kDa showed immunoreactivity with allergenic patients' anti-Af serum, when the samples were run under denaturing and reducing conditions. In the native form an additional third immunoreactive band of about 70 kDa was found. There were no immunoreactive bands toward IgE about 34 kDa. Periodate treatment caused the decrease or disappearance of the immunoreactivity in the bands, demonstrating that epitopes recognized by serum IgE specific to Af are partially composed by carbohydrates (180 and 70 kDa bands) while others (84 kDa) are carbohydrates. Although further investigations are needed, these preliminary results suggest alkaline serine proteinases from Aspergillus fumigatus as one of the factors responsible for the fungal allergenicity.

Antigens, Fungal↗
PubMedDate not supplied

Intrinsically fluorescent cytotoxic cisplatin analogues as DNA marker molecules.

Two square planar derivatives of Pt(en)Cl(2) with intrinsic fluorescence in aqueous solution at room temperature, with quantum yields (Phi) 0.11 and 0.10, respectively, have been synthesized and characterized as [Pt(en)(CG)Cl] (Complex 1) and [Pt(en)(CG)(2)] (Complex 2) (en = ethylenediamine, CG = cholylglycinate). Complexes 1 and 2 exchange just one ligand (chloride or cholylglycinate, respectively) when reacted with water or 5'-GMP to give the same chemical species. After reaction with DNA oligonucleotides or DNA plasmids, they show enhanced emission in the visible region, which lasts for long periods of time and makes them potentially useful DNA marker molecules. Incubation with nucleated blood cells followed by microscopic analyses revealed that they enter the cells within minutes of exposure, selectively stain the DNA, and persist after more than 48 h of exposure. Complexes 1 and 2 display cell cycle phase-independent cytotoxic activity against cisplatin-resistant CHO (Chinese hamster ovarian) tumor cells, with an early onset of their effects. Their slightly different biological effects, as compared to cisplatin, are considered to be linked to the bile acids and their vector properties and to the preferential formation of monoadducts.

Cell Cycle↗