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Biomedical subjects

A Benito

Publications and source records attributed to A Benito.

At least 19 recordsLinked to original sources
PubMed2006

In-situ demonstration of mitogen-activated protein kinase Erk 1/2 signalling pathway in contagious respiratory tumours of sheep and goats.

Ovine pulmonary adenocarcinoma (OPA) and enzootic nasal adenocarcinoma (ENA) are two contagious neoplastic diseases of secretory epithelial cells in the respiratory system of sheep and goats. Jaagsiekte sheep retrovirus (JSRV) is the aetiological agent of OPA, and enzootic nasal tumour virus (ENTV) is associated with ENA. The genomes of these retroviruses do not contain known oncogenes but products of the env gene are important in the generation of transforming stimuli. However, the cell signalling pathways activated in vivo are not completely understood. This study was based on the use of activation stage antibodies specifically detecting proteins of the extracellular signal regulated kinase Erk 1/2 cell signalling pathway and transcription factors. Tissue sections were collected from four natural cases of OPA, four experimentally induced OPA tumours, four ENA tumours in sheep, four ENA tumours in goats, two normal sheep lungs and two lungs with chronic inflammation. Routine immunohistochemical procedures with phosphorylation stage-specific antibodies were carried out. Representative proteins of the Erk1/2 pathway (Raf-1, Mek1/2 and p44/42MAPK) were activated in natural cases of OPA and ENA in sheep and goats and also in experimentally induced OPA. Transcription factors 90Rsk and Elk-1 were activated in OPA and ENA tumours. However, c-Myc was activated only in OPA tumours. In contagious respiratory neoplasms of sheep and goats the Erk1/2 pathway appears to be important for the in-vivo generation of the transforming stimuli.

Adenocarcinoma↗
PubMed2006

A cytotoxic ribonuclease variant with a discontinuous nuclear localization signal constituted by basic residues scattered over three areas of the molecule.

Nuclear import of proteins is determined by specific signals that allow them to bind to receptors that mediate their energy-dependent transport through the nuclear pore. These signals are termed nuclear localization signals and do not constitute a specific consensus sequence. Among them, the most characterized correspond to monopartite and bipartite nuclear localization signals, which interact with the importin alpha/beta heterodimer. We previously described a cytotoxic variant of human pancreatic-ribonuclease that is actively transported into the nucleus. Here, we show that this protein interacts with importin alpha through different basic residues, including Lys1 and the arginine clusters 31-33 and 89-91. Although these residues are scattered along the sequence, they are close in the three-dimensional structure of the protein and their topological disposition strongly resembles that of a classical bipartite nuclear localization signal.

Active Transport, Cell Nucleus↗
PubMed2005

Matuyama-age lithic tools from the Sima del Elefante site, Atapuerca (northern Spain).

Paleomagnetic results obtained from the sedimentary fill at the Sima del Elefante site in Atapuerca, Spain, reveal a geomagnetic reversal, interpreted as the Matuyama-Brunhes boundary (0.78 Ma). The uppermost lithostratigraphic units (E17 through E19), which contain Mode II and III archaeological assemblages, display normal polarity magnetization, whereas the six lowermost units (E9 through E16) yield negative latitudinal virtual geomagnetic pole positions. Units E9 through E13, all of which display reverse magnetic polarity, contain Mode I (Oldowan) lithic tools, testifying to the presence of humans in the early Pleistocene (0.78-1.77 Ma).

Geologic Sediments↗
PubMed2005

An Early Pleistocene hominin mandible from Atapuerca-TD6, Spain.

We present a mandible recovered in 2003 from the Aurora Stratum of the TD6 level of the Gran Dolina site (Sierra de Atapuerca, northern Spain). The specimen, catalogued as ATD6-96, adds to the hominin sample recovered from this site in 1994-1996, and assigned to Homo antecessor. ATD6-96 is the left half of a gracile mandible belonging to a probably female adult individual with premolars and molars in place. This mandible shows a primitive structural pattern shared with all African and Asian Homo species. However, it is small and exhibits a remarkable gracility, a trait shared only with the Early and Middle Pleistocene Chinese hominins. Furthermore, none of the mandibular features considered apomorphic in the European Middle and Early Upper Pleistocene hominin lineage are present in ATD6-96. This evidence reinforces the taxonomic identity of H. antecessor and is consistent with the hypothesis of a close relationship between this species and Homo sapiens.

Adult↗
PubMed2004

Prothrombin fragment 1+2 is associated with carotid intima-media thickness in subjects free of clinical cardiovascular disease.

BACKGROUND AND PURPOSE: Thrombin, a central enzyme in the clotting cascade, plays a role not only in thrombosis but also in the progression of atherosclerosis. We studied the relationship between prothrombin fragment 1+2 (F1+2), a specific marker of thrombin generation in vivo, and carotid intima-media thickness (IMT), an index of subclinical atherosclerosis. METHODS: We examined 181 asymptomatic middle-aged subjects (mean age 55.6 years, 76.7% men) free of overt clinical atherosclerotic disease. F1+2 was measured by enzyme-linked immunosorbent assay and IMT by duplex ultrasonography of carotid artery. Multiple linear regression analysis was used to assess the relationship between the 2 parameters. RESULTS: Compared with individuals in the lowest tertile of F1+2, those in the upper tertile (>0.55 nmol/L) showed significantly higher IMT (P<0.01). In correlation analysis, a positive relationship was found between plasma F1+2 and carotid IMT. F1+2 also correlated positively with cholesterol (P<0.008) and low-density lipoprotein cholesterol (P<0.005), but not with blood pressure or body mass index. In the multivariate analysis, the association of F1+2 with carotid IMT remained significant (P<0.001) after adjustment for age, sex, body mass index, systolic blood pressure, cholesterol, diabetes, and smoking. CONCLUSIONS: In a population sample of adults without clinically overt atherosclerotic disease, the plasma levels of F1+2 were significantly associated with carotid IMT, suggesting a relationship between thrombin generation and the development atherosclerosis.

Arteriosclerosis↗
PubMed2004

Characterization of excretory-secretory products from protoscoleces of Echinococcus granulosus and evaluation of their potential for immunodiagnosis of human cystic echinococcosis.

This study describes, for the first time, the characterization of excretory-secretory antigens (ES-Ag) from Echinococcus granulosus protoscoleces, evaluating their usefulness in the immunodiagnosis of human cystic echinococcosis. ES-Ag were obtained from the first 50 h maintenance of protoscoleces in vitro. This preparation contained over 20 major protein components which could be distinguished by 1-dimensional SDS-PAGE with apparent masses between 9 and 300 kDa. The culture of of protoscoleces from liver produced a greater variety of excretory-secretory protein components than those from lung. Determination of enzymatic activities of secreted proteins revealed the presence of phosphatases, lipases and glucosidases, but no proteases. These findings were compared to those obtained from somatic extracts of protoscoleces and hydatid cyst fluid products. Immunochemical characterization was performed by immunoblotting with sera from individuals infected by cystic echinococcosis (n = 15), non-hydatidic parasitoses (n = 19), various liver diseases (n = 24), lung neoplasia (n = 16), and healthy donors (n = 18). Antigens with apparent masses of 89, 74, 47/50, 32, and 20 kDa showed specificity for immunodiagnosis of human hydatidosis. The 89 and 74 kDa components corresponded to antigens not yet described in E. granulosus, whereas proteins of 41-43 kDa and 91-95 kDa were recognized by the majority of the non-hydatid sera studied.

Animals↗
PubMed2004

Paget's disease of the glans penis secondary to transitional cell carcinoma of the bladder: a report of two cases and review of the literature.

BACKGROUND: Extramammary Paget's disease of the glans penis secondary to transitional cell carcinoma (TCC) of the bladder is rare, with only a few cases reported in the literature. We report two new cases, one detected before diagnosing bladder TCC. METHODS: We describe the clinicopathologic features of two patients with intraepithelial spread of glans TCC and the histochemical and immunohistochemical features of the neoplasm. RESULTS: Light microscopy detected intraepithelial proliferation of neoplastic, large, pale cells located predominantly in the basal and parabasal layers of the epithelium. The pagetoid cells showed positive cytoplasmic staining for mucosubstances and immunoreactivity for CK20. The previously reported cases are reviewed and the differential diagnosis is discussed. CONCLUSIONS: As many benign and malignant glans lesions may be clinically similar, histologic study is necessary to correctly diagnose primary lesions and promptly detect underlying asymptomatic visceral malignancies initially presenting as Paget's disease.

Aged↗
PubMed2004

Malaria vectors in the Bioko Island (Equatorial Guinea): estimation of vector dynamics and transmission intensities.

The current study was performed on the Bioko Island (Equatorial Guinea) with the aim of establishing a rapid assessment technique for mapping malaria risk and measuring vector densities. Human bait collection, tent traps, light traps, indoor resting collection, and window exit traps were used to collect Anopheles gambiae s.s. and Anopheles funestus, the two anopheline species involved in malaria transmission in this island. Capture data were used to compare differences in the behavior and vectorial capacity of An. gambiae s.s. and An. funestus. Differences in the two species of mosquitoes were found in relation to the season and trapping methods used. Entomological inoculation rates (EIR) for Plasmodium falciparum were calculated using a polymerase chain reaction (PCR) test with individual anopheline mosquitoes from human bait collections in two villages during the dry and rainy seasons. P. falciparum sporozoites were detected from both dissected heads/thorax and abdomens of both species.

Animals↗
PubMed2003

A new chromo-chemodosimeter selective for sulfide anion.

A new chromo-chemodosimeter for the anion sulfide in aqueous environments has been developed. The recognition concept is based on a pyrylium-thiopyrylium transformation that is conveniently drawn toward "color chemistry" concepts by means of the anchoring of an aniline group. This causes the color of the aniline-pyrylium backbone in L1 to change selectively from magenta to blue when transformed to the corresponding aniline-thiopyrylium in the presence of the sulfide anion. The method is simple and easy, suggesting potential applications in a variety of different environments where easy and rapid determination of sulfide might be required.

Journal Article↗
PubMed2002

Stabilization of human pancreatic ribonuclease through mutation at its N-terminal edge.

Enzyme stability can be an important parameter in the design of recombinant toxins because unstable proteins are often degraded before they can reach their cellular target. There is great interest in the design of human pancreatic ribonuclease variants that could be cytotoxic against tumoral cells. To this end, some residues in the protein need to be substituted, but this may result in a loss of stability. Previous papers have reported the production of N- and C-terminal human pancreatic ribonuclease variants with increased thermal stability. Here, we investigated the contribution of the different amino acid changes at the N-terminus of the protein to its thermostability increase. We show that this increase correlates with the helical propensity of the first alpha-helix of the protein. On the other hand, deletion of the four last residues of the protein does not affect its thermal stability. These results set the basis for the design of a human pancreatic ribonuclease template on which amino acid substitutions can be made that could render the enzyme cytotoxic, without an important loss in its stability.

Enzyme Stability↗
PubMed2002

Malaria vectors in Bioko Island (Equatorial Guinea): PCR determination of the members of Anopheles gambiae Giles complex (Diptera: Culicidae) and pyrethroid knockdown resistance (kdr) in An. gambiae sensu stricto.

Anopheles gambiae sensu lato Giles, 1902 and Anophelesfunestus Giles, 1900 are the main malaria vectors on the island of Bioko (Equatorial Guinea). This study was carried out to determine: a) members of the An. gambiae complex that may be present on the island of Bioko and, b) the sensitivity of An. gambiae sensu stricto to pyrethroids. The analysis by PCR detected the presence of An. gambiae s.s. as the major vector of the complex and the "forest chromosomal form" was demonstrated by cytogenetic analysis. The presence of Anopheles melas in the southwest, north and southeast of the island justifies its study as a vector. The molecular characterization of pyrethroid knockdown resistance (kdr) showed that the populations of An. gambiae s.s. were sensitive and no mutations were found. This fact justifies the implementation on a large scale of pyrethroid-impregnated bednets within the framework of the Malaria Control Program of Equatorial Guinea.

Animals↗
PubMed2001

Bimp1, a MAGUK family member linking protein kinase C activation to Bcl10-mediated NF-kappaB induction.

Bcl10 and MALT1, products of distinct chromosomal translocations in mucosa-associated lymphoid tissue lymphoma, cooperate in activating NF-kappaB. Mice lacking Bcl10 demonstrate severe immunodeficiency associated with failure of lymphocytes to activate nuclear factor kappaB (NF-kappaB) in response to antigen receptor stimulation and protein kinase C activation. We characterize Bimp1, a new signaling protein that binds Bcl10 and activates NF-kappaB. Bimp1-mediated NF-kappaB activation requires Bcl10 and IkappaB kinases, indicating that Bimp1 acts upstream of these mediators. Bimp1, Bcl10, and MALT1 form a ternary complex, with Bcl10 bridging the Bimp1/MALT1 interaction. A dominant negative Bimp1 mutant inhibits NF-kappaB activation by anti-CD3 ligation, phorbol ester, and protein kinase C expression. These results suggest that Bimp1 links surface receptor stimulation and protein kinase C activation to Bcl10/MALT1, thus leading to NF-kappaB induction.

Adaptor Proteins, Signal Transducing↗
PubMed2001

The structure of an engineered domain-swapped ribonuclease dimer and its implications for the evolution of proteins toward oligomerization.

BACKGROUND: Domain swapping has been proposed as a mechanism that explains the evolution from monomeric to oligomeric proteins. Bovine and human pancreatic ribonucleases are monomers with no biological properties other than their RNA cleavage ability. In contrast, the closely related bovine seminal ribonuclease is a natural domain-swapped dimer that has special biological properties, such as cytotoxicity to tumour cells. Several recombinant ribonuclease variants are domain-swapped dimers, but a structure of this kind has not yet been reported for the human enzyme. RESULTS: The crystal structure at 2 A resolution of an engineered ribonuclease variant called PM8 reveals a new kind of domain-swapped dimer, based on the change of N-terminal domains between the two subunits. The swapping is fastened at both hinge peptides by the newly introduced Gln101, involved in two intermolecular hydrogen bonds and in a stacking interaction between residues of different chains. Two antiparallel salt bridges and water-mediated hydrogen bonds complete a new interface between subunits, while the hinge loop becomes organized in a 3(10) helix structure. CONCLUSIONS: Proteins capable of domain swapping may quickly evolve toward an oligomeric form. As shown in the present structure, a single residue substitution reinforces the quaternary structure by forming an open interface. An evolutionary advantage derived from the new oligomeric state will fix the mutation and favour others, leading to a more extended complementary dimerization surface, until domain swapping is no longer necessary for dimer formation. The newly engineered swapped dimer reported here follows this hypothetical pathway for the rapid evolution of proteins.

Amino Acid Sequence↗
PubMed2001

Amplified fragment length polymorphism (AFLP) protocol for genotyping the malarial parasite Plasmodium falciparum.

We have established an amplified fragment length polymorphism (AFLP) protocol for identifying anonymous polymorphic loci of the malarial parasite, Plasmodium falciparum. The method consists of the following steps (i) digestion and ligation in one reaction; (ii) selective fluorescence forward primers labelled; (iii) PCR products resolved in polyacrylamide gels using the ABIPRISM 377 XL DNA sequencer and, (iv) the use of Genescan software to size the fragments. This standardized protocol distinguished between 2 standard reference clones of P. falciparum from West African and Southeast Asian and 2 Central African isolates from patients with clinical malaria. The AFLP protocol resulted in evenly distributed and reproducible band patterns for amplified fragments ranking from 163 to 489 bp long +/-0.5 S.D. The primer Tru ACA labelled with the phosphoramidite 6-carboxifluorescein (FAM-blue) was easy to interpret, with a maximum of 53 bands per clone and of 81 per isolate (mixed falciparum populations) whereas the primer Tru AG labelled with the hexachlorinated analogue (HEX-green) showed a less clear pattern of bands and reproducibility than Tru ACA.

Animals↗