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J Sánchez

Publications and source records attributed to J Sánchez.

At least 19 recordsLinked to original sources
PubMed2007

Permeability changes of Manduca sexta midgut brush border membranes induced by oligomeric structures of different cry toxins.

The pore-formation activity of monomeric and oligomeric forms of different Cry1 toxins (from Cry1A to Cry1G) was analyzed by monitoring ionic permeability across Manduca sexta brush border membrane vesicles. The membrane vesicles were isolated from microvilli structures, showing a high enrichment of apical membrane markers and low intrinsic K(+) permeability. A fluorometric assay performed with 3,3'-dipropylthiodicarbocyanine fluorescent probe, sensitive to changes in membrane potential, was used. Previously, it was suggested that fluorescence determinations with this dye could be strongly influenced by the pH, osmolarity and ionic strength of the medium. Therefore, we evaluated these parameters in control experiments using the K(+)-selective ionophore valinomycin. We show here that under specific ionic conditions changes in fluorescence can be correlated with ionic permeability without effects on osmolarity or ionic strength of the medium. It is extremely important to attenuate the background response due to surface membrane potential and the participation of the endogenous permeability of the membrane vesicles. Under these conditions, we analyzed the pore-formation activity induced by monomeric and oligomeric structures of different Cry1 toxins. The Cry1 toxin samples containing oligomeric structures correlated with high pore activity, in contrast to monomeric samples that showed marginal pore-formation activity, supporting the hypothesis that oligomer formation is a necessary step in the mechanism of action of Cry toxins.

Animals↗
PubMed2006

Role of receptor interaction in the mode of action of insecticidal Cry and Cyt toxins produced by Bacillus thuringiensis.

Cry toxins from Bacillus thuringiensis are used for insect control. Their primary action is to lyse midgut epithelial cells. In this review we will summarize recent findings on the Cry toxin-receptor interaction and the role of receptor recognition in their mode of action. Cry toxins interact sequentially with multiple receptors. In lepidopteran insects, Cry1A monomeric toxins interact with the first receptor and this interaction triggers oligomerization of the toxins. The oligomer then interacts with second receptor inducing insertion into membrane microdomains and larval death. In the case of mosquitocidal toxins, Cry and Cyt toxins play a part. These toxins have a synergistic effect and Cyt1Aa overcomes Cry toxin resistance. Recently, it was proposed that Cyt1Aa synergizes or suppresses resistance to Cry toxins by functioning as a membrane-bound receptor for Cry toxin.

Bacillus thuringiensis↗
PubMed2006

Relative importance of CD4+ and CD8+ T cells in the resolution of Chlamydophila abortus primary infection in mice.

The role of the specific cellular immune response is well established in Chlamydiaceae infections, but the importance of each T-cell subset seems to be species-dependent. This study was designed to clarify the role of T-cell subsets in the response to Chlamydophila abortus primary infection. C57BL/6 mice were depleted of CD4+ or CD8+, or both, by monoclonal antibody injections and subsequently infected with C. abortus. Mice were killed at intervals and samples were collected for bacteriological and histopathological analysis. Also carried out were spleen cell culture, cytokine quantification, immunolabelling for C. abortus antigen, and a TUNEL assay for apoptosis. CD8+ T cell-depleted mice all died within 12 days of C. abortus infection, while no mortality was observed in the other groups; surprisingly, CD4+ T cell-depleted mice showed lower morbidity (expressed as weight loss) than did a non-depleted (control) group. CD8+ T cell-depleted mice also differed from the other groups in showing a significantly higher chlamydial burden in the liver. CD8+ T cell-depleted mice also had a higher number of apoptotic cells in hepatic inflammatory foci and showed exacerbated IFN-gamma production by spleen cells after specific stimulation. Simultaneous depletion of both T-cell subpopulations led to a chronic infection, but not to early mortality. It is concluded that CD8+ T cells may play a role in the regulatory control of the CD4+ T-cell response and may have a direct cytotoxic or IFN-gamma-mediated effect on infected cells.

Animals↗
PubMed2006

Assessing heavy metal sources in agricultural soils of an European Mediterranean area by multivariate analysis.

According to the European Thematic Strategy for Soil Protection, the characterization of the content and source of heavy metals in soils are necessary to establish quality standards on a regional level that allow the detection of sampling sites affected by pollution. In relation to this, the surface horizons of 54 agricultural soils under vegetable crops in the Alicante province (Spain), a representative area of the European Mediterranean region, were sampled to determine the content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Analytical determinations were performed by atomic absorption spectroscopy after microwave sample digestion in acid solution. Results indicated that heavy metal levels were similar to those reported by authors working on agricultural soils from other parts of the Mediterranean region, with the exception of Cu and Pb in some samples. Multivariate analysis (principal component analysis and cluster analysis) was performed to identify a common source for heavy metals. Moreover, soil properties were determined in order to characterize agricultural soils and to analyze relationships between heavy metal contents and soil properties. The content of Co, Cr, Fe, Mn, Ni and Zn were associated with parent rocks and corresponded to the first principal component called the lithogenic component. A significant correlation was found between lithogenic metals and some soil properties such as soil organic matter, clay content, and carbonates, indicating an important interaction among them. On the other hand, elements such as Cd, Cu and Pb were related to anthropic activities and comprised the second (Cu and Pb) and third principal components (Cd), designated the anthropogenic components. Generally, Cd, Cu and Pb showed a lower correlation with soil properties due to the fact that they remain in available forms in these agricultural soils. Taking into account these results and other achieved in other parts of the European Mediterranean region, it can be concluded that soil quality standards are highly needed to declare soils affected by human induced pollution. This is particularly relevant for anthropogenic metals (Cd, Cu and Pb, and in some areas also Zn). Further research in other agricultural areas of the region would improve the basis for proposing such soil quality standards.

Agriculture↗
PubMed2006

Coral diversity and disease in Mexico.

Field studies and empirical tests of the 'diversity-disease hypothesis' demonstrate the effects of species richness on disease transmission and severity in plant systems. Yet the converse, i.e. effects of disease on diversity, is rarely considered in either relatively well-studied plant systems or marine ecosystems. We investigated these effects along the Mexican Yucatan Peninsula to (1) quantify the relationship between disease prevalence and coral diversity, (2) test the hypothesis that octocoral and scleractinian disease prevalence are associated with one another, and (3) establish a long-term dataset. Aspergillosis of sea fans and 6 scleractinian diseases were documented. Prevalence of aspergillosis declined from 12.85% in 2002 to 5.26% in 2004, while prevalence of scleractinian diseases remained relatively constant at 5.7 +/- 0.8% in 2002 and 7.96 +/- 0.7% in 2004. Sites were relatively rich (71 species of octocoral and scleractinian corals) and even (E5 > 0.5). Sea fan disease prevalence was not associated with scleractinian disease prevalence, nor were there consistent associations between disease and measures of diversity. However, the most abundant octocoral and scleractinian species are susceptible to infection with several diseases, and disease may alter coral diversity in complex ways. These data represent the first in what will become a long-term dataset monitoring disease prevalence and associated changes in coral diversity.

Analysis of Variance↗
PubMed2006

Heparin coating durability on artificial heart valves studied by XPS and antithrombin binding capacity.

The durability and functionality of a heparin coating on artificial heart valve leaflets were evaluated with X-ray photoelectron spectroscopy (XPS) and by the coatings' capacity to bind antithrombin. Current methods for accelerated life-time testing are based on exposing leaflets to water solutions. In this paper a method is explored, in which heart valve leaflets were exposed to a continuous high shear rate (4 L/min) of human citrated plasma. It was found that the heparin coating was stable and wear resistant enough to still be present after 3 weeks and to have about the same antithrombin uptake as coatings not exposed to circulating plasma. It was, however, partly destroyed by the test as found using XPS. We suggest that heparin chains from the upper layer of heparin have been torn off from the carrier chain, in combination with loss of heparin conjugate and plasma deposition in patches. This study showed that XPS provides additional information to biological measurements such as antithrombin uptake. XPS is therefore a valuable technique not only to characterize biomaterials but also to evaluate the effect of a performance test.

Antithrombins↗
PubMed2006

Resistin as a putative modulator of insulin action in the daily feeding/fasting rhythm.

Resistin and adiponectin are adipokines with postulated opposite functions. Resistin has been related with insulin resistance in obesity, while adiponectin could be associated to higher insulin sensitivity. We have determined whether the production of these two adipokines during the day is related to the feeding rhythm in rats. Resistin mRNA levels in adipose tissue correlated positively with the gastric contents and serum insulin concentration, showing higher levels during the dark phase (period of the highest food intake), especially in the mesenteric depot, while levels decreased during the light phase. The diurnal pattern of resistin expression was not directly reflected in the circulating levels, but it showed a 6-h delay and correlated negatively with the gastric contents and serum insulin. Adiponectin expression followed an opposite pattern, not apparently related to feeding or insulin release, and not translated into changes in circulating levels. Moreover, considering that insulin stimulates resistin expression and that circulating resistin follows a contrary circadian pattern in comparison to insulin, resistin, apart from its role in the increased insulin resistance associated to obesity, could also act as a putative modulator of insulin in the daily feeding/fasting rhythm through a negative feedback regulation of its action.

Adiponectin↗
PubMed2006

Attitudes of primary care professionals in Spain toward xenotransplantation.

OBJECTIVE: The deficit in transplantable organs is making it necessary to find alternative sources. One possibility is xenotransplantation. However, the use of animal organs may be rejected by society and among health professionals. Primary Care is fundamental for promoting matters of health; in Spain it has access to nearly 100% of the population. Our objective was to analyze the acceptance of this therapy, although it is experimental, among Primary Care professionals, given that they are the ones most involved in spreading information about this therapy if it was confirmed to be useful. MATERIALS AND METHODS: A random sample was stratified by sex, job category, and geographical location among Primary Care personnel, including 428 professionals in 32 health centers among population of 2851 professionals. Attitudes toward xenotransplantation were evaluated using a questionnaire on psychosocial attitudes validated in our geographical area. Contact was made in each center with the Doctor Coordinator for doctors, the Nursing Coordinator for nurses, and an Administrative Officer for ancillary personnel. The chi-square test and Student t test were applied to evaluate categorical and continuous data, respectively. RESULTS: Attitudes toward xenotransplantation were similar to those obtained in human organs: favorable in 79% (n = 325), whereas 19% (n = 78) had doubts and 2% (n = 10) were against. The attitude was more favorable in men (89% vs 72%; P < .000), those who had cared for transplant patients (84% vs 71%; P = .009), those with previous experience in organ donation and transplantation (84% vs 75%; P = .033), those with an attitude in favor of cadaveric organ donation (83% vs 66%; P < .0001), and those in favor of living donation of the kidney (P < .000) or the liver (P < .000), as well as those who believed that they may need a transplant at some time in the future (84% vs 74%; P = .045). There was a clear difference in attitude according to job category (P = .018): approval rates were 89% for doctors, 76% for nurses, and 70% for ancillary personnel. CONCLUSIONS: Attitudes toward future application of xenotransplantation were quite positive among doctors. However, the attitudes of nursing and ancillary personnel were similar to those of the general population. The main factors related to such an attitude depended mainly on the previous relationship and attitude of the respondent toward human organ donation and transplantation.

Animals↗
PubMed2006

Primary care doctors faced with living organ donation.

OBJECTIVE: The attitudes of health care personnel, specifically doctors, have a significant influence on public attitudes toward organ donation and transplantation. The objective herein was to analyze the attitudes of Primary Care (PC) doctors toward living organ donation and to determine the psychosocial factors that condition these attitudes. MATERIALS AND METHODS: A random sample was stratified by geographical location (six health areas in our community) among PC doctors, including 155 respondents from 32 health centers. Attitudes toward donation were evaluated using a psychosocial questionnaire validated in our geographical area. Contact was made with the Doctor Coordinator in each center for distribution of the questionnaires, which were completed anonymously. The chi-square test and Student t test were applied to evaluate the data. RESULTS: When the living donor is not related, only 21% (n = 32) of PC doctors were in favor of living kidney donation, and only 20% (n = 31) for living liver donation (P > .05). In contrast, these percentages were 90% and 89% in favor of kidney and liver related donation, respectively. Upon analysis of the psychosocial variables affecting these attitudes, there was only an association with their partner's opinion (P = .009 for kidney and P = .000 for liver), and the possibility of needing a transplant oneself (P = .000). CONCLUSIONS: PC doctors have favorable attitudes toward related living donation. If living donation is promoted by transplant coordination units, such PC professionals could act as a source of positive information about the matter for the general public.

Attitude of Health Personnel↗
PubMed2006

Information requested about organ donation in primary health care centers.

UNLABELLED: Information provided by primary care workers about organ donation significantly affects the attitude of the general public. The objective of this study was to evaluate information about donation requested by the general public in health centers in an autonomous community (region) of Spain and to find out how many workers provided relevant information. MATERIALS AND METHODS: A random sample was taken and stratified by sex, job category, and geographical location (six health areas of our autonomous regional community, 45 municipal councils), among primary care health workers in order to obtain a total of 428 respondents in 34 primary care centers. A study was undertaken of information requested and provided about organ donation and transplantation. The chi square test was applied and differences were considered significant at levels of P < .05. RESULTS: Forty-three percent (n=185) of the workers surveyed indicated that information had been requested from them about organ donation and transplantation. This request for information was much greater from physicians than from the other types of workers (P = .015). Furthermore, 54% of primary care health workers (n=229) reported having provided information about donation, especially physicians (64%), with this being mainly favorable. Information had also been provided by nurses (59%) and ancillary staff (34%). CONCLUSION: Information requested from primary care health workers by the general public about organ donation and transplantation is increasing when we compare it to data from previous years. Around half of primary care workers have offered information about transplantation. Therefore, it is fundamental that these workers have adequate and correct information to provide patients and families.

Attitude to Death↗
PubMed2006

Effects of policosanol on patients with ischemic stroke: a pilot open study.

Stroke is a major health problem worldwide. Its pharmacological management includes thrombolytic therapy for the acute phase and antiplatelet drugs for stroke recovery and prevention. Statins can help in the acute phase and in preventing stroke in secondary prevention patients. Policosanol is a cholesterol-lowering drug with concomitant antiplatelet effects, with protective effects in stroke models. This observational study investigated the effects of policosanol (20 mg/day) administered during the acute phase and for 5 years later on the neurological recovery of patients with ischemic stroke treated with antiplatelets and vitamins. After hospital discharge, patients were followed up every 3 (first year) and 6 (thereafter) months. Neurological improvement was assessed with the modified Canadian Neurological Scale. Adverse events were recorded. Fifty patients were included; all completed the study. Neurological score improved throughout the study. No patient died, and most [40 (80.0%)] did not experience new vascular events; only one (2.0%) suffered a new stroke, and two (4.0%) suffered more than one transient ischemic attack. The time to the first recurrent event was 46.2 months. Policosanol persistently lowered serum total cholesterol, with such reduction correlating with the neurological improvement (R = 0.995253301). Triglycerides were unchanged. Treatment was well tolerated. Policosanol administered to patients suffering ischemic stroke treated with aspirin and vitamins showed good results on neurological outcomes and recurrent events. This study, however, has limitations, since it was open and uncontrolled, and patients also consumed aspirin and vitamins. New randomized, controlled studies are needed to assess the usefulness of policosanol in stroke management.

Aged↗
PubMed2006

[Optic neuritis after meningococcal vaccination].

CASE REPORT: We report the case of a 13 year-old male with bilateral optic neuritis after meningococcal C vaccination. He was treated with intravenous corticosteroids, but only showed visual recovery in one eye. A significant limitation of his sharp vision remained in his other eye. DISCUSSION: There have been no previously reported cases of optic neuritis after meningococcal C vaccination and for this reason we have reported this case. It is not possible, however, to exclude some other factor in the etiology of the optic neuritis, but the temporal relationship between the neuritis and the vaccination suggests this was the cause.

Adolescent↗
PubMed2005

Microbial community structure at different depths in disturbed and undisturbed semiarid Mediterranean forest soils.

Metabolic abilities and micrfiobial community structure were investigated through three semiarid Mediterranean soils of SE Spain. The soils were (1) a Typic Calcixerept under an adult pine plantation (PP), growing on abandoned agricultural terraces; (2) a Typic Calcixeroll under a native pinewood (NP); and (3) a Typic Haploxerept covered with a grass steppe (GS). PP and NP were similar as regards their genesis, but the former used to be tilled. NP and GS were undisturbed and supported natural and seminatural vegetation, respectively. Seven samples in 10-cm depth increments were taken in triplicate along each soil profile. Community-level physiological profiles based on sole-C-source use were determined to characterize the metabolic abilities. A 16S rDNA polymerase chain reaction-denaturing gradient gel electrophoresis analysis was performed to investigate the microbial genetic structure. Plant cover and land-use history were major determinants of microbial community structure. Microbial communities residing in soils under a native pinewood, the most diverse and stable plant cover, were the most complex both metabolically and genetically. The microbial community structure distinctly changed with depth, related to the quantity and quality of total organic carbon. Both undisturbed soils showed falling gradients of metabolic and genetic complexity, which were invariably of a greater magnitude in the mature woodland than in the grass steppe. In the planted pinewood, however, the substrate-use diversity increased with depth, apparently a response to the depleted metabolic abilities within its upper layer (0-30 cm). Tilling and plant cover removal might be responsible for such a perturbation. In the same profile, molecular fingerprint patterns of the topsoil layer (0-10 cm) indicated a disturbed genetic structure that might underlie the loss of metabolic abilities. However, the genetic structure of the deeper layers of the planted and native pinewoods was not dissimilar, revealing that equivalent genetic resources perform different environmental functions under changing soil scenarios.

Bacteria↗
PubMed2005

Variability, repeatability and phenotypic relationships of several characteristics of production and semen quality in rabbit.

A total of 2140 ejaculates from 156 adult males pertaining to four groups of bucks were analysed and the following traits were recorded: pH, ejaculate volume (V), mass motility (Mm), individual motility (Mi), concentration (Cn), total number of spermatozoa per ejaculate (TSE), percentage of sperm viability (Vi), percentage of sperm with acrosome integrity (NAR), percentage of sperm normalcy (Nr), percentage of sperm morphological abnormalities of head (H), neck-midpiece (Nm) and tail (T) and presence of proximal and distal cytoplasmic droplet (Dp, Dd). Principal component (PC) analysis and phenotypic correlations were performed in order to examine the relationships between qualitative and quantitative traits of rabbit semen. The repeatability of the traits measured was also estimated. Phenotypic correlations between sperm traits were estimated as the residual correlation from an analysis of variance, including the effects of: genetic type of the male, order of the ejaculate, day of collection and the permanent non-additive random effect of the male to which the observation corresponds. The repeatability of these traits was analysed separately, in a set of univariate analyses, using VCE software. The previously defined mixed model was used for this analysis. The principal component analysis was performed using the Princomp procedure of the SAS v.8 package. The first four PC explained 62% of total variation: 23%, 18%, 12% and 8%, respectively. Percentage of sperm viability, NAR, Nr, T and Nm were the predominant variables in the first PC. Mass motility, Mi, pH, Cn and TSE were located in the second. Percentage of sperm with the presence of proximal and distal cytoplasmic droplet, NAR, Vi and Nr were the predominant traits in the third and V defined the fourth. Repeatability of semen quality traits was moderate for most of the traits. The highest values (about 0.45) corresponded to V, Cn, Nr and Dp and the lowest (about 0.10) to H and Nm. Repeatability of the first ejaculate was greater than that of the second for pH, Mm, Mi, H, Dp and Dd.

Acrosome↗
PubMed2005

Norfloxacin decreases bacterial adherence of quinolone-resistant strains of Escherichia coli isolated from patients with cirrhosis.

BACKGROUND: Long-term administration of norfloxacin is recommended for secondary prophylaxis of spontaneous bacterial peritonitis in cirrhosis, but it may be associated with the development of quinolone-resistant bacteria in stools. However, these bacteria rarely cause infections. AIM: To assess bacterial adherence of either quinolone-sensitive or -resistant Escherichia coli obtained from stools of cirrhotic patients, as one of the main virulence factors, and its variations when sub-minimum inhibitory concentration of norfloxacin were added to the medium. METHODS: E. coli strains were co-cultured with oral epithelial cells obtained from patients in presence/absence of norfloxacin. Bacterial adherence was measured as percentage of cells exhibiting positive adherence and the number of bacteria attached to epithelial cells. RESULTS: 37 sensitive and 22 resistant E. coli strains were studied. Bacterial adherence was similar in both series (78% vs. 81%, P = N.S.), and these percentages were similarly and significantly reduced when subminimum inhibitory concentration of norfloxacin was added to the culture medium (P < 0.001). CONCLUSIONS: Bacterial adherence of E. coli obtained from patients with cirrhosis is unrelated to the sensitivity/resistance to quinolones, and is similarly reduced in both cases when subminimum inhibitory concentration of norfloxacin is added to the medium.

Anti-Infective Agents↗
PubMed2005

Rural primary care centers as a source of information about organ donation.

INTRODUCTION: Primary care is an important way of promoting health in the community, and this includes organ donation. In rural areas, this way of promoting health acquires special importance. Our objective was to analyze attitudes toward organ donation among primary care workers in rural health centers to assess their importance in circulating information about donation. MATERIALS AND METHODS: A random sample, stratified according to job category among the primary care staff (n = 160), of workers in rural areas in our autonomous community (population < 10,000 inhabitants), evaluated attitudes toward donation using a questionnaire validated in our geographic area. To distribute the questionnaire it was necessary to contact the following in each health center: the coordinating physician, the nursing coordinator, and an administrative worker. RESULTS: Of those questioned, 78% (n = 124) were in favor of donation, as opposed to 22% (n = 36) who are against it or undecided. As for the job category, physicians and nurses showed a more favorable attitude than nonhealth workers (90% and 80% vs 61%; P = .000). The psychosocial variables that were related to such an attitude were knowledge of the concept of brain death (P = .013) and lack of fear of manipulation of the deceased person (P = .002). Regarding information about organ donation and transplantation, 54% (n = 86) reported having been provided favorable information, with up to a quarter of the physicians considering other programs to be of greater interest for primary care than organ donation and transplantation. CONCLUSION: Attitudes toward organ donation were favorable among a high percentage of primary care workers in rural centers; more than 50% have circulated favorable information on the subject. However, there is a high percentage with a negative or undecided attitude, especially among nonhealth workers, which should be reversed with promotional activities at the level of the health center.

Attitude to Health↗