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P Acevedo

Publications and source records attributed to P Acevedo.

11 recordsLinked to original sources
PubMed2006

Estimation of European wild boar relative abundance and aggregation: a novel method in epidemiological risk assessment.

Wild boars are important disease reservoirs. It is well known that abundance estimates are needed in wildlife epidemiology, but the expense and effort required to obtain them is prohibitive. We evaluated a simple method based on the frequency of faecal droppings found on transects (FBII), and developed a spatial aggregation index, based on the runs test statistic. Estimates were compared with hunting data, and with porcine circovirus and Aujeszky's disease virus seroprevalences and Mycobacterium tuberculosis complex and Metastrongylus spp. prevalence. The FBII and the aggregation index were correlated with the hunting index, but both of the former estimates correlated better than the latter with the disease prevalences. Hence, at least in habitats with high wild boar densities, the FBII combined with the aggregation index constitutes a cheap and reliable alternative for wild boar abundance estimation that can be used for epidemiological risk assessment, even outside the hunting season and in areas with no available data on hunting activities.

Animals↗
PubMed2006

Design of a continuous wave blood flow bi-directional Doppler system.

This paper describes the design of a continuous wave blood flow bi-directional Doppler system based on an open, high-resolution architecture that is portable and low cost. The system incorporates the advantages of expensive systems with dedicated hardware. The system is composed of a flow detector probe, a signal conditioning stage, a direction detection module, a signal processing stage and a graphic user interface. The direction detection of the signal is achieved using a fast digital phasing filter. The Doppler signal is processed using a short-time Fourier transform-based algorithm. This is commonly used as a reference. Nevertheless, the system allows us to incorporate alternative high-resolution spectral estimation methods that might offer more precise information to the specialist.

Algorithms↗
PubMed2006

Changes in parasite transmission stage excretion after pheasant release.

The production of parasite transmission stages was investigated in the faeces of 77 farm-bred ring-necked pheasants (Phasianus colchicus). Coccidian oocysts (Eimeria sp.), and nematode eggs (Heterakis sp., and Capillaria-like eggs) were recovered before and after release but all birds were treated prior to release. Treatment with fenbendazole significantly reduced the abundance of transmission-stage excretion for all parasites, and reduced the prevalence in the case of Eimeria sp. and Heterakis sp. Nonetheless, a significant increase in the excretion abundance for all parasites and in the prevalence of Eimeria sp. and Heterakis sp. was found after release. Eggs of Ascaridia sp. were found only after releasing, suggesting infection ocurred in the wild. A negative relationship was found between the pheasant body condition and Heterakis excretion abundance and a higher abundance of Capillaria sp. eggs in female birds. No significant relationship was found between parasite excretion abundance and pheasant survival. Despite this, results suggest that an increase in the excretion of parasite transmission stages follows the release of captive pheasants into the wild. This can in part explain restocking failures, but also means that autochtonous free-living birds may become exposed to new and potentially harmful pathogens. To avoid these risks it is proposed that improved prophylactic measures should be taken.

Animals↗
PubMed2005

Serosurvey of Aujeszky's disease virus infection in European wild boar in Spain.

Serum samples from 693 hunted wild boar (Sus scrofa) were analysed by means of a blocking ELISA technique, and the mean (se) prevalence of antibodies to Aujeszky's disease virus was 44 (4) per cent. All the seropositive wild boar were from south central Spain, except for one from central Spain, close to the main positive area. In this area, where large game species are increasingly managed for hunting, the seroprevalence was affected by the type of management. More intensively managed populations had a higher prevalence than wild boar living in natural situations, and the seroprevalence increased with the age of the animals; the seroprevalence was higher in females in all age groups. The seroprevalence in males more than one year old peaked after the breeding season, whereas females of the same age had a higher and constant seroprevalence throughout the year.

Animals↗
PubMed2005

Relationship between bronchopulmonary nematode larvae and relative abundances of Spanish ibex (Capra pyrenaica hispanica) from Castilla-La Mancha, Spain.

The excretion of bronchopulmonary nematode infective larvae was evaluated in 160 faecal samples of Spanish ibex (Capra pyrenaica hispanica) collected from 13 populations in Castilla-La Mancha, south-central Spain in September 2003. Intensities and prevalences were compared with pasture availability, abundances of wild and domestic ungulates at both levels, i.e. for populations and for faeces in a two-step procedure. Protostrongylid larvae showed similar infection rates (mean intensity: 1.56+/-0.12, n=94; mean prevalence: 25.62+/-6.86%, n=160) to Dictyocaulus spp. (mean intensity: 1.03+/-0.11, n=48; mean prevalence: 30.00+/-7.11%, n=160). At the population level, positive correlations were found between the prevalences of both bronchopulmonary taxa. The prevalence in both groups, but not intensity, also correlated positively with Spanish ibex abundance indexes both for the populations and individual faeces. These findings suggest that: (i) parasite spreading across Spanish ibex populations in Castilla-La Mancha could respond to host density-dependent processes; and (ii) these populations may have similar exposition and/or susceptibility to both bronchopulmonary taxa resulting in similar host-parasite patterns, despite their different life cycles. Bronchopulmonary outputs in the Spanish ibex from Castilla-La Mancha seems not to represent a health risk for this endemic wild ungulate but may be useful in any health surveillance scheme for the increasing populations of Spanish ibex.

Animals↗
PubMed2000

Thickness measurement in composite materials using lamb waves viscoelastic effects.

Pulse propagation in plates has been investigated with the identification of Lamb modes. The application of this technique to the measurement of thickness in composite and coarse materials was previously evaluated. As a sequel, results of the application of this technique taking into account the viscoelastic properties of PVC and ferrocement are presented.

Elasticity↗
PubMed1995

Upregulation of gap junctional communication and connexin43 gene expression by carotenoids in human dermal fibroblasts but not in human keratinocytes.

Consumption of dietary carotenoids has been statistically associated with decreased risk of cancer at several anatomic sites. In a model murine system of carcinogenesis (the 10T1/2 assay), we have previously shown that carotenoids can inhibit chemically and physically induced neoplastic transformation. This action is strongly correlated with the ability of carotenoids to increase gap-junctional communication (GJC) by induction of connexin43 (Cx43) gene expression. Here we extend these studies to human foreskin-derived dermal fibroblasts and keratinocytes. In fibroblasts, beta-carotene and canthaxanthin at concentrations between 10(-5) and 3 x 10(-6) M were found to strongly enhance GJC in a dose- and time-dependent manner. This was accompanied by an increase in the number of immunofluorescent junctional plaques recognized by an anti-Cx43 antibody and by an increase in Cx43 protein level as determined by western blot analysis. No decrease in proliferation rates was detected by [H3]thymidine labeling. Human keratinocytes grown in monolayer culture did not respond to carotenoids in terms of GJC as measured by dye transfer, immunofluorescent analysis of Cx43 distribution, or Cx43 levels as measured by western blotting. Both cell types accumulated high levels of carotenoids. Because canthaxanthin, which has no known provitamin A activity in mammals, is as active in fibroblasts as is beta-carotene, the carotenoid with the highest provitamin A activity, the induction of GJC and Cx43 expression by carotenoids in human dermal fibroblasts seems unrelated to their provitamin A status. The lack of response of keratinocytes suggests differences in regulation of Cx43 expression or in carotenoid processing.

Anticarcinogenic Agents↗
PubMed1995

Liarozole potentiates the cancer chemopreventive activity of and the up-regulation of gap junctional communication and connexin43 expression by retinoic acid and beta-carotene in 10T1/2 cells.

Liarozole has been reported to inhibit P450 enzymes responsible for the catabolism of retinoic acid. This suggests that it may increase the effectiveness of cancer chemopreventive agents, such as retinoic acid, and pro-vitamin A carotenoids, such as beta-carotene, which may yield retinoids. To test this we have utilized the 10T1/2 cell assay system of neoplastic transformation. Simultaneous treatment with Liarozole (10(-5) M) potentiated by a factor of 1000 the ability of low concentrations of retinoic acid (10(-10) M) to inhibit carcinogen-induced neoplastic transformation, to up-regulate gap junctional communication and to increase connexin43 expression. When tested under conventional culture conditions, Liarozole itself partially suppressed neoplastic transformation and up-regulated gap junctional communication; this ability appears due to the presence of retinol in the serum component of cell culture medium. When assays for junctional communication and of connexin43 expression were performed under defined conditions, in the absence of serum, Liarozole was ineffective alone, yet still augmented the effects of retinoic acid. HPLC analysis of cell culture medium demonstrated that Liarozole (10(-5) M) completely protected retinoic acid (10(-6) M) from catabolism over a 48 h period. Potential effects of Liarozole on the activities of carotenoids were also examined. Inhibition of neoplastic transformation by the pro-vitamin A carotenoid beta-carotene, but not by the non-pro-vitamin A carotenoid canthaxanthin, was moderately potentiated by Liarozole. The augmentation of response to beta-carotene was more apparent when tested under defined conditions; here Liarozole strongly increased junctional communication and Cx43 expression. In contrast, Liarozole did not potentiate the activity of canthaxanthin under defined conditions, while increasing the activity of 4-keto retinoic acid, a likely metabolite. Liarozole also elevated connexin43 expression in early passage human fibroblasts. These data indicate that rapid catabolism of retinoic acid limits its in vitro activities, that a portion of the action of beta-carotene as a cancer preventive agent is due to its conversion to retinoic acid and that canthaxathin exerts its chemopreventive action largely independent of conversion to 4-keto retinoic acid.

Animals↗
PubMed1994

The mitogenic effects of transforming growth factors beta 1 and beta 2 in C3H/10T1/2 cells occur in the presence of enhanced gap junctional communication.

It has been proposed that the transfer of growth regulatory signals via gap junctions is important in the control of proliferation. In confluent 10T1/2 cells, growth control is enhanced by retinoids; this action is highly correlated with up-regulated gap junctional communication (GJC). Treatment of quiescent 10T1/2 cells with transforming growth factor (TGF) beta 1 and TGF-beta 2 resulted in elevated levels of proliferation together with increased expression of connexin43 protein and elevated GJC. Connexin43 was localized into plaques in regions of cell-cell contact; such plaques were found at high frequency in treated cells but only rarely in control cultures. These data illustrate that increased cell proliferation can occur in the presence of enhanced GJC, a result at variance with our previous results with retinoids. We suggest that either the proliferative stimulus of TGF-beta is sufficient to overwhelm any antiproliferative effect of GJC or that under conditions of TGF-beta stimulation, junctions convey net proliferative stimuli.

Animals↗
PubMed1992

Gap-junctional protein connexin 43 is expressed in dermis and epidermis of human skin: differential modulation by retinoids.

Retinoids are effective modulators of proliferation and differentiation of keratinocytes in vivo and in vitro. In mouse 10T1/2 cells, retinoid action on proliferation and neoplastic transformation is correlated with the upregulation of gap-junctional communication and expression of connexin 43 (Cx43). In the present study we have determined if retinoids induce similar effects on gene expression in human skin. Studies were conducted in intact skin and on cultured keratinocytes and dermal fibroblasts. In a clinical study, 2 weeks of treatment with 0.05% all-trans retinoic acid resulted in increased expression of Cx43 mRNA and protein in epidermis. Expression occurred predominantly in the suprabasal layer. Cultured cells exhibited a differential response to retinoic acid. In keratinocytes, increased expression of Cx43 occurred at low (10(-11) M) concentrations, whereas inhibition occurred at high (10(-7) M) concentrations; however, junctional communication, measured by dye transfer, was not altered over this concentration range. Dermal fibroblasts, in contrast, exhibited a dose-dependent increased expression of Cx43 at concentrations up to 10(-7) M retinoic acid and proportionately increased their junctional communication over this dose range. These data indicate that control of Cx43 gene expression by retinoids in human skin cells is complex. The production of gradients of junctional channels could play a role in the control of growth and differentiation in epidermis.

Cells, Cultured↗