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Biomedical subjects

A Figueras

Publications and source records attributed to A Figueras.

At least 37 records · Page 2Linked to original sources
PubMed2001

Proteolytic activity of cultured Pseudoperkinsus tapetis extracellular products.

Several pathogenic protozoan release proteases are necessary for host invasion and initiation of infection. We have identified proteolytic activities in extracellular proteins secreted by the clam parasite Pseudoperkinsus tapetis (Mesomycetozoa) in vitro. The protein concentration of the P. tapetis extracellular products (ECP) increased only during the first week of culture. The appearance of new proteins of 10 and 157 kDa at the second week sample and of 12 kDa at the third week sample was shown by SDS-PAGE. The protease activity rapidly increased in the first 3 weeks of culture, and five clear bands of 23, 29, 60, 67 and 96 kDa with proteolytic activity were detected in the ECP on gelatin SDS-PAGE. Using inhibitors, the proteases were identified as members of the Ca(2+) dependent, serine protease family. Their optimum pH was higher than pH 9.4. The protease activity of the P. tapetis ECP was different than that described for Perkinsus marinus, an oyster pathogen very similar morphologically to the clam parasite and member of the genus in which P. tapetis had been initially included.

Animals↗
PubMed2000

Neoparamoeba Page, 1987: light and electron microscopic observations on six strains of different origin.

Although amoebic gill disease (AGD) has emerged as one of the most severe health problems in the fish industry, proof of the identity of AGD agents from various localities is still missing. Six strains of amoebae designated until recently as Paramoeba species (the agents of AGD) were studied in cultures by light and electron microscopy. Although they were isolated from gills of different hosts (Dicentrarchus labrax and Scophthalmus maximus) and from distant localities, their morphology was identical. The strains differed from Paramoeba eilhardi, the type species of the genus, in that they lacked the boat-shaped microscales on the cell surface but could be safely identified as belonging to the genus Neoparamoeba Page, 1987. Transmission electron microscopy revealed the presence of a symbiotic organism, Perkinsiella amoebae Hollande, 1980, in all strains under study. The only difference among the strains examined was found in the size of trophozoites, which could be attributed to the different origins of the strains, but until more refined diagnostic methods are available, in addition to N. pemaquidensis, the closely related species N. aestuarina also has to be taken into consideration as the agent of AGD.

Amebiasis↗
PubMed2000

Virus-like particles associated with mortalities of the carpet-shell clam Ruditapes decussatus.

During the late summer and early fall of 1997 and 1998 heavy mortalities were detected in the carpet-shell clam Ruditapes decussatus cultured in Galicia (NW Spain). The prevalences and intensities of the parasites found in the histopathological studies were not high enough to explain the high mortality rates. Unenveloped virus-like particles were detected by transmission electron microscopy in the cytoplasm of the connective tissue cells. They had an icosahedrical-spherical shape with a diameter of 27 to 35 nm. These virus-like particles appeared free in the cytoplasm or associated with endoplasmic reticulum membranes. These characteristics suggest that they belong to the Picornaviridae family.

Animals↗
PubMed2000

Immune parameters in carpet shell clams naturally infected with Perkinsus atlanticus.

Defence parameters of non-infected clams (Ruditapes decussatus) and clams heavily infected with Perkinsus atlanticus were assessed. Cellular (haemocyte density and phagocytic activity) and humoral (lysozyme and anti-bacterial activities, protein concentration and agglutination titre) parameters were measured in clams collected in an area enzootic for P. atlanticus. The infection intensity of each clam was assessed, and the immune parameters measured in the most infected clams were compared with those measured in the non-infected ones. Only the serum anti-bacterial activity and the agglutination titre were significantly different between infected and non-infected clams. The phagocytic rate, haemocyte density, lysozyme concentration and protein concentration were not statistically different but they showed the same trend in the two trials performed. Phagocytic rate, haemocyte concentration and anti-bacterial activity were higher in non-infected clams, while they had lower lysozyme concentration, serum protein concentration and agglutination titre than infected clams. Although infected and healthy clams were not different for every parameter measured, probably due to the high variability among individuals, P. atlanticus seems to affect the clam immune system, at least in advanced stages of the infection.

Animals↗
PubMed2000

Modulation of the chemiluminescence response of Mediterranean mussel (Mytilus galloprovincialis) haemocytes.

The influence of several factors on the chemiluminescence (CL) activity of haemocytes from the Mediterranean mussel (Mytilus galloprovincialis) was studied. Haemocytes were stimulated in vitro with different concentrations of zymosan, phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS) (adding superoxide dismutase, SOD, to the zymosan-stimulated haemocytes in order to test the specificity of the reaction). The in vitro effect of the clam pathogens Vibrio tapetis (bacteria) and a Perkinsus atlanticus-like protozoan tentatively named Pseudoperkinsus taapetis on the mussel haemocytes CL response was also assessed. To study the in vivo stimulation of haemocytes, mussels were inoculated with zymosan and the CL response of their haemocytes was subsequently measured. Zymosan added in vitro produced the highest CL response, although PMA also enhanced the CL emission and, in addition, increased the zymosan-stimulated CL. LPS and V. tapetis did not activate haemocytes. SOD significantly decreased the CL emission in zymosan-stimulated haemocytes. P. tapetis cells, as well as their extracellular products, inhibited the CL response to zymosan. Haemocytes from mussels injected with zymosan showed lower levels of stimulation than in vitro treated cells, and CL increased with time after injection.

Animals↗
PubMed1999

Role of nitric oxide on the replication of viral haemorrhagic septicemia virus (VHSV), a fish rhabdovirus.

In the present work, we have studied the role of nitric oxide (NO) on the replication of viral haemorrhagic septicemia virus (VHSV), a virus which produces high mortalities in fish aquaculture worldwide and that is known to replicate in turbot (Scophthalmus maximus) head kidney macrophages. Viral infection of turbot kidney macrophages in vitro induced an up-regulation of NO production and we have tested whether this endogenous NO production induced by VHSV on macrophages had an antiviral effect using the NO synthase inhibitor, N-omega-nitro-L-arginine (L-NAME). When L-NAME was added to the VHSV-infected cultures, no increase on VHSV titer was observed, even though the inhibitor was capable of decreasing NO production. When exogenous NO was apported by the nitric oxide donor, glycerin trinitrate (GTN) an antiviral effect on VHSV was observed. The NO donor significantly inhibited VHSV replication on a turbot fibroblast cell line (TV-1) and on turbot kidney macrophages.

Animals↗
PubMed1999

Epizoic amoebae from the gills of turbot Scophthalmus maximus.

Species of amoebae belonging to the genera Platyamoeba Page, 1969, Vannella Bovee, 1965 and Flabellula Schaeffer, 1926 were found to accompany Paramoeba sp., the agent of amoebic gill disease (AGD), in clinically diseased turbots. The same community of epizoic gymnamoebae was found on the gills of turbots which revealed no gill abnormalities but slight behavioral signs indicative of suboptimal health status. The assemblage of the above-mentioned free-living amoebae capable of colonizing gill tissue of turbots was supplemented with species recognized in samples fixed from primary isolates for transmission electron microscopy. The pathogenic potential of epizoic gill amoebae in turbots is discussed.

Amebiasis↗
PubMed1999

Production of leukotriene B4 and prostaglandin E2 by turbot (Scophthalmus maximus) leukocytes.

Production of two eicosanoids derived from lipoxygenase and cyclooxygenase activities: leukotriene B4 (LTB4) and prostaglandin E2 (PGE2), respectively, have been simultaneously determined in turbot (Scophthalmus maximus) blood leucocyte and kidney macrophage supernatants by a reverse phase high performance liquid chromatography (HPLC) system coupled with a Diode-Array detector. Levels of LTB4 after calcium ionophore challenge were 4.08 ng ml-1 in blood leukocyte supernatants and 0.25 ng ml-1 in kidney macrophage supernatants. The levels found for PGE2 were 428.23 and 606.67 ng ml-1 in blood leukocytes and kidney macrophage supernatants, respectively. When blood leukocytes were treated with the respective inhibitors for the enzymes implicated on the synthesis of both compounds an inhibition of 90.35% was observed for PGE2 and 76.44% for LTB4. The detection limit of the method was 0.15 ng ml-1 for LTB4 and 50 ng ml-1 for PGE2.

Animals↗
PubMed1998

Influence of the sequence of administration of beta-glucans and a Vibrio damsela vaccine on the immune response of turbot (Scophthalmus maximus L.).

Yeast (Saccharomyces cerevisae) beta-1,3 glucans were used as adjuvant in a Vibrio damsela vaccine for turbot (Scophthalmus maximus L.). Turbot were injected with the adjuvant prior, at the same time and after the vaccine. Several immune parameters (index and rate of phagocytosis, passive haemolytic plaque numbers, and agglutinating antibody titers) were determined at different times postinoculation. The highest activity of all the immune parameters was obtained when glucans were injected after the bacterin. It is concluded that the sequence of glucan administration is critical when used as a vaccine adjuvant.

Adjuvants, Immunologic↗
PubMed1998

Paramoeba sp., an agent of amoebic gill disease of turbot Scophthalmus maximus.

Amoebic gill disease of turbot Scophthalmus maximus L. associated with mortalities was repeatedly diagnosed at culture facilities in NW Spain. The agent was assigned to the genus Paramoeba Schaudin, 1896. Trophozoites found in the gill tissue as well as those cultured displayed most of the principal characteristics of P. pemaquidensis Page, 1970. The identity with P. pemaquidensis, known as an agent of gill diseases of salmonids, is yet to be assessed using non-morphological criteria.

Amebiasis↗
PubMed1998

In vitro interaction of viral haemorrhagic septicaemia virus and leukocytes from trout (Oncorhynchus mykiss) and turbot (Scophthalmus maximus).

Viral haemorrhagic septicaemia virus (VHSV), a well known salmonids pathogen, has also been reported to be pathogenic for turbot (Scophthalmus maximus). In the present work, the replication of VHSV was studied in vitro in turbot head kidney macrophages and blood leukocytes. VHSV was able to infect both primary cultures and viral titer increased with time, either inside the cells or in the supernatant. However, no cytopathic effect was observed during the experiments and the titers were always lower than those obtained in the fish cell lines. The number of trout and turbot macrophages after several days of in vitro infection with VHSV was compared with uninfected controls by viable cell count but no significant differences were observed. The number of cells supporting viral replication evaluated by immunofluorescence in trout and turbot was low (8 and 1.7%, respectively). Respiratory burst activity of head kidney macrophages was assayed at different days post-infection, but no significant differences were found between the control and the infected cultures neither in trout nor turbot.

Animals↗
PubMed1998

Characterization and Infectivity of Four Bacterial Strains Isolated from Brown Ring Disease-Affected Clams

Four bacterial strains isolated from carpet-shell clams (Ruditapes decussatus) and manila clams (R. philippinarum) exhibiting Brown Ring Disease (BRD) symptoms in Galicia (Northwest of Spain) were characterized using biochemical and serological techniques. Moreover their pathogenicity for clams and resistance against clam hemolymph were determined. All of the Vibrio isolates exhibited biochemical characteristics typical of the genus. Strains GR1703RP and GR6301RP, isolated from R. philippinarum showing signs of BRD, shared phenotypical and antigenic characteristics and bacterial extracellular products enzymatic activities with the Vibrio tapetis. Strains GR0705RD and GR0202RD, isolated from R. decussatus showing BRD signs, although biochemically similar to V. tapetis, did not show positive agglutination with V. tapetis antiserum. The virulence of the bacteria varied depending on the bacterial strain and clam species assayed. Mortalities were recorded for a 30-day period, reaching values ranging from 6 to 80%. Strain GR0202RD was the most virulent for R. philippinarum with a cumulative mortality rate of 45%, while the strain GR0705RD induced the highest prevalence of BRD signs, affecting 75% of the survivors. In the case of R. decussatus, the four bacterial strains produced a cumulative mortality rate higher than 45%. In general, bacterial strains, showed resistance to clams hemolymph. Copyright 1998 Academic Press. Copyright 1998 Academic Press

Journal Article↗
PubMed1997

Ductal carcinoma in situ of the breast: correlation between histologic classifications and biologic markers.

The expression of hormone receptors (estrogen and progesterone), c-erb-B2 (neu), p53, and Ki-67) was studied by immunohistochemical analysis in a series of 94 carcinomas in situ of the breast. The tumors were classified in two (high grade vs. low grade) and three (high grade vs. intermediate grade vs. low grade) categories. High-grade carcinomas were well defined by biologic markers showing statistically significant differences for all of the parameters tested. No clear biologic distinction, however, between low-grade and intermediate-grade cancers could be obtained. Negative progesterone receptors and a high proliferative index are the best discriminant parameters for the final assignment of doubtful cases.

Adult↗