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J Meseguer

Publications and source records attributed to J Meseguer.

At least 37 records · Page 2Linked to original sources
PubMed2002

Natural cytotoxic activity in seabream (Sparus aurata L.) and its modulation by vitamin C.

Isolated gilthead seabream head-kidney leucocytes were incubated in a culture medium supplemented with vitamin C (from 0-control-to 2 mg ml(-1)) or with a combination of different amounts of vitamin C (0.002 to 2 mg ml(-1)) and vitamin E (0.01 to 10 microg ml(-1)) for 6, 24 or 48 h. Afterwards, the cellular ascorbic acid content and the natural cytotoxic activity of leucocytes were evaluated. Leucocyte ascorbic acid levels were enhanced after incubation for 6-24 h with 0-2 mg of vitamin C ml(-1) and above. The natural cytotoxic activity of leucocytes after incubation with vitamin C was also increased for all the assayed concentrations and incubation times except in the case of the highest vitamin C concentration (2 mg ml(-1)) and the longest incubation time (48 h). No statistically significant differences in leucocyte cytotoxic activity were observed when vitamin E was added to the vitamin C, compared with the results of vitamin C alone. For the in vivo study, fish were fed diets supplemented with vitamin C (2.9 g kg(-1) diet) without or with vitamin E (1.2 g of vitamin E kg(-1) diet) for 2, 4 or 6 weeks. Serum lysozyme activity was enhanced to a statistically significant degree when fish were fed with the vitamin C + E supplemented diet for 2 weeks and with the vitamin C and vitamin C + E supplemented diets for 4 weeks. Both groups of fish showed a statistically significant increase in the natural cytotoxic activity of head-kidney leucocytes after 6 weeks of treatment although no differences were observed between treatments incorporating vitamin C alone or vitamin C combined with vitamin E.

Animals↗
PubMed2002

Changes in some innate defence parameters of seabream (Sparus aurata L.) induced by retinol acetate.

The effects of high doses of dietary or intraperitoneally (i.p.) injected retinol acetate on the gilthead seabream (Sparus aurata L.) innate immune system were studied. Gilthead seabream specimens were fed a commercial non-supplemented diet containing 1.75 mg of vitamin A kg(-1) (as control) or the same diet supplemented with 50, 150 or 300 mg of retinol acetate kg(-1) (as vitamin A source). After 1, 2, 4 or 6 weeks, serum samples and head-kidney leucocytes were obtained from each fish. Serum lysozyme activity and myeloperoxidase (MPO) content were unaffected by the vitamin A diet content. The phagocytic and respiratory burst activities of head-kidney leucocytes were established, as well as their myeloperoxidase content. While phagocytosis was not enhanced by dietary vitamin A intake and was even slightly decreased after 2 weeks, respiratory burst activity was enhanced in specimens fed supplements of 150 and 300 mg retinol acetate kg(-1) diet for 1 or 2 weeks. Leucocyte MPO content was also enhanced when seabream were fed the highest vitamin A dose for 2 or 4 weeks and after being fed the 150 or 50 mg supplemented diets for 4 or 6 weeks, respectively. Three different groups of seabream were i.p. injected with 1 ml of phosphate buffer containing an amount of retinol acetate equivalent to the daily dietary supplements from the first experiment (0-control-, 0.05 or 0.30 mg 100 g(-1) biomass). Both injection doses of retinol acetate were toxic for the gilthead seabream which showed hypervitaminic effects. These data show that retinol acetate plays an important role in the gilthead seabream nonspecific cellular immune system due to its antioxidant properties. They also point to the importance of the way in which it is administered, by dietary uptake or intraperitoneal injection.

Adjuvants, Immunologic↗
PubMed2001

Interleukin-1beta isolated from a marine fish reveals up-regulated expression in macrophages following activation with lipopolysaccharide and lymphokines.

The gilthead seabream IL-1beta gene consists of five exons/four introns. The complete coding sequence contains a 102 bp 5' untranslated region (UTR), a single open reading frame of 762 bp which translates into a 253 amino acid molecule, and a 407 bp 3'UTR with a polyadenylation signal 14 nucleotides upstream of the poly(A)tail. The seabream sequence has the highest degree of nucleotide (61.7%) and amino acid (53%) identity with the trout IL-1beta sequences. The IL-1beta message was detected by RT-PCR in head-kidney, blood, spleen, liver, gill and peritoneal exudate of both non-infected and Vibrio anguillarum-challenged fish. More importantly, IL-1beta was highly expressed by purified macrophage monolayers and was up-regulated by lipopolysaccharide and lymphocyte-derived macrophage-activating factor stimulation.

Amino Acid Sequence↗
PubMed2001

Effect of oral administration of high vitamin C and E dosages on the gilthead seabream (Sparus aurata L.) innate immune system.

The effect of the oral administration of high dosages of vitamins C and E on the innate immune system of the seabream was investigated. Gilthead seabream (Sparus aurata L.) were fed four different diets for 45 days: a commercial diet as control, a 3g/kg vitamin C-supplemented diet, a 1.2g/kg vitamin E-supplemented diet or a diet containing both vitamin supplements. After 15, 30 and 45 days, serum ascorbic acid and alpha-tocopherol levels, growth, complement titers and head-kidney leucocyte phagocytic and respiratory burst activities were evaluated. The results showed that serum vitamin levels reflected dietary input. Fish fed the vitamin C-supplemented diet showed an enhanced respiratory burst activity, while fish fed the vitamin E-supplemented diet exhibited increased complement and phagocytic activities. All of these positive effects were found in fish fed the joint diet, as well as a synergistically enhanced respiratory burst activity at day 30. The results demonstrate that in vivo vitamins C and E exert a synergistic effect enhancing the respiratory burst activity of seabream phagocytes.

Administration, Oral↗
PubMed2001

Effects of short-term crowding stress on the gilthead seabream (Sparus aurata L) innate immune response.

Gilthead seabream specimens were subjected to an intense short-term crowding stress of 100 kg m(-3) for 2 h. After 0, 1, 2, 3 and 4 days, blood glucose and serum cortisol levels, serum complement activity, phagocytic and respiratory burst activities of head-kidney leucocytes, and the percentage of monocyte/ macrophages and granulocytes in head-kidney and circulating blood were determined. An immediate effect of the stress was a depression in complement and phagocytic activities, both of which recovered after 3 or 2 days, respectively, while respiratory burst remained unaffected. The depression of phagocytosis in head-kidney leucocytes seemed to correlate with stress-induced migration of active cells from the organ to circulating blood. The present results point to the importance of minimising intense short-term crowding stress in order to reduce possible states of immunodepression in farmed fish.

Animals↗
PubMed2001

Immunomodulatory effects of dietary intake of chitin on gilthead seabream (Sparus aurata L.) innate immune system.

To determine the effects of chitin (poly [1-->4]-beta-N-acetyl-D-glucosamine) on the innate immune response of gilthead seabream (Sparus aurata L.), fish were fed diets containing 0 mg (control), 25, 50 or 100 mg kg(-1) chitin for 2, 4 and 6 weeks. Lysozyme and natural haemolytic complement activities, together with head-kidney leucocyte respiratory burst, phagocytic and cytotoxic activities, were studied at each of the assayed times. Lysozyme activity was unaffected by the administration of chitin. The innate humoral and cellular immune response activities assayed were enhanced by the dietary intake of chitin, each increasing at a different time: natural haemolytic complement activity and cytotoxic activity after 2 weeks of treatment, respiratory burst activity from 4 weeks and phagocytic activity after 6 weeks, although, unlike the other activities, no statistically significant differences were observed in the first. The results indicate that chitin increases the activity of the seabream innate immune system, and its use as an immunostimulant is discussed, especially with regards to the protective role.

Animals↗
PubMed2001

Vitamin E increases natural cytotoxic activity in seabream (Sparus aurata L.).

The natural cytotoxic activity of head-kidney leucocytes from gilthead seabream (Sparus aurata L.), after in vitro and in vivo vitamin E treatment, against tumor cells was studied by flow cytometry. Leucocytes were incubated in culture medium with different vitamin E supplementations (0.01-10 microg ml(-1)) for 6, 24 or 48 h and the results demonstrate that all the assayed vitamin E supplementations significantly enhanced the natural cytotoxic activity of leucocytes. To determine the effect of a high dietary level of vitamin E on this activity, fish were fed with 0 (control), 600, 1200 or 1800 mg of vitamin E supplementation kg(-1) diet for 2, 4 or 6 weeks. After 2 and 4 weeks of treatment, the natural cytotoxic activity was significantly enhanced at the highest (1.8 g kg(-1) diet) and lowest (600 mg kg(-1) diet) vitamin E supplement dosage, respectively. No effect of the vitamin E supplemented diet on seabream leucocyte natural cytotoxic cell activity was observed after 6 weeks of treatment.

Animals↗
PubMed2001

A fish cell surface receptor defined by a mAb mediates leukocyte aggregation and deactivation.

Cell adhesion molecules play a key role in the inflammatory response. Selectins, integrins and immunoglobulin gene superfamily adhesion receptors mediate the different steps of leukocyte migration from the blood-stream towards inflammatory foci. In addition to their adhesive function, these receptors modulate major cellular processes such as cell activation, growth, differentiation and death. To characterise the fish molecules involved in cell adhesion, a panel of mAbs was raised by immunising mice with macrophages from the marine fish gilthead seabream (Sparus aurata L.). One of these mAbs, which we named anti-Aggregatin, was found to induce a rapid heterotypic aggregation of seabream leukocytes. Anti-Aggregatin defined a 140-kDa cell surface receptor which was highly expressed by macrophages and was up-regulated after co-stimulation with LPS and MAF. Functionally, the cell adhesion which occurred upon exposure to anti-Aggregatin required Ca(2+), an intact cytoskeleton and an active cell metabolism. More importantly, Aggregatin engagement resulted in strong inhibition of the phagocyte respiratory burst, although the cells showed neither loss of viability nor DNA fragmentation. The results are discussed in relation to the potential role of cell adhesion molecules in fish immune responses.

Animals↗
PubMed2000

Blood cells of sea bass (Dicentrarchus labrax L.). Flow cytometric and microscopic studies.

Studies of fish blood cells made to date presented numerous problems derived from both the nomenclature and the techniques used. A combination of quantitative and morphological methods is needed if the classification of fish blood cells is to advance from it present provisional state. The aim of the present paper was first to isolate sea bass blood cell populations by flow cytometry and second to characterize then microscopically. Blood cell populations from sea bass (Dicentrarchus labrax L.) were isolated according to their FSC (size) and SSC (granularity) properties by flow cytometry. The isolated populations were then processed for light and transmission and scanning electron microscopic characterization. Sea bass blood leukocytes isolated by flow cytometry consisted of two main cell subpopulations. Subsequent microscopic study of these cells revealed that the first subpopulation was composed of small cells (3-5 microm) of low granularity and consisted of thrombocytes and lymphocytes whereas, the second subpopulation was formed of 6-9 microm sized cells of high granularity consisting of granulocytes and monocyte/macrophages. The combined use of flow cytometry and electron microscopy makes it possible to characterize the different cell types present in sea bass peripheral blood with a high degree of certainty. Although sea bass basically follows the common vertebrate hematological pattern, significant modifications such as the presence of circulating immature erythrocytes, plasma cells and monocyte/macrophages and different forms of thrombocytes can be established with respect to this pattern.

Animals↗
PubMed2000

High dietary intake of alpha-tocopherol acetate enhances the non-specific immune response of gilthead seabream (Sparus aurata L.).

To determine the effects of three high levels of dietary intake of alpha-tocopherol acetate (vitamin E) on the non-specific immune response of gilthead seabream (Sparus aurata L.), specimens were fed a commercial diet (100 mg alpha-tocopherol kg-1) as control, or vitamin E supplemented diets (600, 1200 or 1800 mg alpha-tocopherol acetate kg-1) for 15, 30 or 45 days. Growth, serum alpha-tocopherol levels, natural haemolytic complement activity and head-kidney leucocyte migratory, respiratory burst and phagocytic activities were studied at each of the assay times. A positive correlation between alpha-tocopherol acetate intake and serum alpha-tocopherol levels was observed, the increase being linked to both the dosage and length of treatment. Specimens fed the diet supplemented with 600 mg vitamin E kg-1 showed no enhancement in any of their immune parameters, while those fed the diet supplemented with 1200 mg vitamin E kg-1 presented a slightly higher (but not statistically significant) specific growth rate than fish fed the other diets. In addition, serum haemolytic activity and the phagocytosis of head-kidney leucocytes were enhanced by the dietary intake of 1200 mg vitamin E kg-1 after 30 and 45 days of treatment, although leucocyte migration and respiratory burst activity remained unaffected. The highest vitamin E dietary dose used, 1800 mg kg-1, unexpectedly provoked no immunostimulation. These results indicate that a moderate level of vitamin E in the diet (1200 mg kg-1) stimulates the seabream's non-specific immune system after 30 days of administration. Lower or higher vitamin E concentrations may not be so effective, because of an imbalance in the vitamin E ratio with other antioxidants. The proposed dietary levels of vitamin together with the indicated administration time could be useful for reducing the susceptibility of farmed fish to infectious diseases.

Animals↗
PubMed2000

Effects of injecting chitin particles on the innate immune response of gilthead seabream (Sparus aurata L.).

To determine the effects of chitin (poly [1-->4]-beta-N-acetyl-D--glucosamine) particles on the innate immune response of gilthead seabream (Sparus aurata L.), specimens were injected intravenously or intraperitoneally with the substance. Natural haemolytic complement activity, head-kidney leucocyte respiratory burst activity and phagocytic and cytotoxic activities were analysed in vitro 3, 5 or 10 days post-injection. All the immune parameters assayed remained unaffected when chitin was intravenously administered. However, the fish that had been intraperitoneally injected showed increased humoral and cellular immune responses. Natural haemolytic complement activity increased from 5 days post-injection although no statistically significant differences were observed. Respiratory burst and phagocytic activities peaked at 3 and 5 days post-injection, respectively, while cytotoxic activity had increased by 3 days post-injection and remained high until 10 days post-injection.

Animals↗
PubMed1999

Natural cytotoxic activity of gilthead seabream (Sparus aurata L.) leucocytes. Assessment by flow cytometry and microscopy.

This paper describes an easy and sensitive flow cytometric assay for assessing the non-specific cytotoxic activity of gilthead seabream (Sparus aurata L.) head-kidney leucocytes against tumor target cells. Concomitantly, the cytotoxic process and the cell types involved were microscopically studied. The assay was based on the consecutive use of two fluorochromes. The targets were preincubated with 3,3'-dioctadecyloxacarbocyanine perchlorate (DiO) and then mixed with effectors. At the end of incubation time propidium iodide (PI) was added. While live effectors were non-fluorescent, live and dead targets retained the DiO (green) fluorescence and non-viable targets and effectors showed PI (red) fluorescence staining. The kinetics of the cytotoxic activity was studied from 10 to 240 min. Lymphocytes, monocyte-macrophages and granulocytes showed non-specific cytotoxic activity, as demonstrated by light and electron microscopy. In conclusion, the technique presented validates the effectiveness of a dual-color flow cytometric assay for assessing the activity of non-specific cytotoxic cells in fish.

Animals↗
PubMed1998

Effects of in vitro addition of exogenous vitamins C and E on gilthead seabream (Sparus aurata L.) phagocytes.

The phagocytic cell function is an important factor of resistance to infection in fish. Although it is known that several nutritional factors affect phagocyte function and that vitamins C and E modulate the vertebrate immune system, there are no data on the direct effect of these vitamins or on their possible synergistic effects on the fish phagocyte functions. We report the in vitro effect of vitamin C and/or E on the functions and ultrastructure of gilthead seabream (Sparus aurata L.) head-kidney phagocytic leukocytes. Head-kidney leukocytes were incubated with different concentrations of vitamins C and/or E for 48 h and then their migration, respiratory burst, phagocytosis and ultrastructure were studied. Leukocyte migration and phagocytosis increased when vitamin C or E were added, while the respiratory burst was synergistically enhanced when both vitamins were used together. Noticeable ultrastructural changes not previously reported were induced by these vitamins in gilthead seabream phagocytes (acidophilic granulocytes and macrophages). These results indicated that vitamins C and E added in vitro modulate the main functions of gilthead seabream phagocytes and induced ultrastructural changes characteristic of cell activation on such cells.

Animals↗
PubMed1998

Methodological aspects of assessing phagocytosis of Vibrio anguillarum by leucocytes of gilthead seabream (Sparus aurata L.) by flow cytometry and electron microscopy.

In this paper we optimize a flow cytometric method for evaluating the phagocytic activity of leucocytes in gilthead seabream (Sparus aurata L.) and characterize the phagocytic cells observed. Optimal conditions were established for the fluorescein-labelling and analysis of the bacterium Vibrio anguillarum by flow cytometry. Head-kidney leucocytes were incubated with the heat-killed fluorescein isothiocyanate (FITC)-labelled bacteria for different periods, during which the kinetics of phagocytosis was studied. Attached and interiorized bacteria were distinguished. Although phagocytic ability reached a maximum after 60 min, phagocytic capacity reached its maximum at 20 min. The amount of ingested bacteria per phagocyte was estimated from the mean fluorescence of the leucocytes. Cytochalasin B or colchicine was used to inhibit phagocytosis. Monocyte-macrophages and acidophilic granulocytes showed phagocytic activity as demonstrated by transmission electron microscopy. In conclusion, the technique presented allows the screening of thousands of cells, and individual cell evaluation, by quantifying interiorized particles in fish phagocytes. Our ultrastructural results demonstrate that V. anguillarum is actively phagocytized by seabream macrophages and acidophilic granulocytes.

Animals↗
PubMed1998

Role of nitric oxide on the central hemodynamic response to acute volume expansion in the pregnant rat.

OBJECTIVES: Our hypothesis was that during pregnancy nitric oxide acts as mediator in the hemodynamic response to volume expansion. STUDY DESIGN: The study was performed on 12 rats on days 19 to 20 of pregnancy. Six rats were injected intravenously with hexamethonium bromide plus the inhibitor of nitric oxide synthase L-nitro-arginine methyl ester. For a control group, six rats were injected with hexamethonium bromide plus the L-nitro-arginine methyl ester vehicle. A volume expansion (1.2% body weight) was performed in both groups by intravenous infusion of bovine albumin (6%) solution. RESULTS: In the control group volume expansion induced a hyperdynamic circulation characterized by increased cardiac output, decreased total vascular resistance, and no change in arterial pressure; however, in the study group volume expansion induced a pressor response without hyperdynamic circulation. CONCLUSION: During pregnancy volume expansion induces a hyperdynamic circulatory state possibly mediated by nitric oxide release. A defect in the release of nitric oxide may be responsible for an inadequate hemodynamic response to volume expansion.

Animals↗
PubMed1998

Left main coronary artery patch angioplasty: midterm experience and follow-up with spiral computed tomography.

BACKGROUND: Patch angioplasty is an alternative surgical technique in cases of left main coronary artery stenosis. We report our experience with this technique, with particular mention of the use of spiral computed tomography for the follow-up of our patients. METHODS: In this retrospective study we analyzed the results obtained in all 7 patients (3 women and 4 men) who were operated on with this technique in our institution between July 1992 and August 1994. Five consenting patients also underwent graft patency assessment with spiral computed tomographic imaging. RESULTS: The operation was uneventful in all patients and there were no hospital deaths. Two patients required reoperation (1 of them dying at reoperation), 1 because of restenosis of the graft and 1 because of the presence of a new stenosis in the proximal anterior descending coronary artery. The remaining 5 patients were asymptomatic after 51 +/- 2 months. Spiral computed tomographic images were artifacted and of poor quality. CONCLUSIONS: Patch angioplasty of the left main coronary artery can be a valuable therapeutic method in selected cases. Conventional spiral computed tomography is not an optimal noninvasive method for the assessment of graft patency.

Adult↗