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L Mata

Publications and source records attributed to L Mata.

At least 19 recordsLinked to original sources
PubMed2007

Development of a simple enzyme immunoassay for the determination of ovine luteinizing hormone.

The present study describes the development and validation of a simple sensitive and specific sandwich enzyme immunoassay (EIA) for the quantification of ovine luteinizing hormone (LH) in plasma. Microtitre plates were coated with the capture antibody 518b7 anti-bovine LH. A second peroxidase-labelled anti-ovine LH antibody was used as tracer. A simple 3-step procedure was used for the sample analysis; (1) incubation of standards and samples with the pre-coated antibody plates for 2 h at 37 degrees C; (2) incubation with the peroxidase-labelled antibody for 1 h at room temperature; and (3) colour development with TMB substrate. A linear dose-response curve was obtained in the range 0-10 ng/ml (r2 > 0.99). The detection limit was 0.05 ng/ml, and the intra-assay and inter-assay coefficients of variation were 7% and 11.7%, respectively. The theoretical stability of microplates and reagents was calculated, this being greater than one year. Low or undetectable cross-reactivities were recorded for follicle-stimulating hormone, bovine thyroid-stimulating hormone, equine chorionic gonadotrophin and a gonadotrophin-releasing hormone (GnRH) analogue. The EIA was biologically validated by the determination of plasma LH concentrations of nine Rasa Aragonesa ovariectomized and estradiol-implanted ewes after a double GnRH challenge. In conclusion, this enzyme immunoassay provides an efficient, simple and sensitive method for the routine analysis of ovine LH.

Animals↗
PubMed1999

Cystic fibrosis patients with the 3272-26A-->G mutation have mild disease, leaky alternative mRNA splicing, and CFTR protein at the cell membrane.

We characterized the 3272-26A-->G mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, creating an alternative acceptor splice site in intron 17a, that competes with the normal one, although we predict from consensus values, with lower efficiency. We analyzed five Cystic Fibrosis (CF) Portuguese patients with the 3272-26A-->G/F508del genotype. Besides clinical and haplotype characterization of those patients, we report here results from CFTR transcript analysis in nasal brushings from all five patients. RT-PCR analysis supports alternative splicing in all patients and carriers, but not in controls. By sequencing, we determined that the alternative transcript includes 25 nucleotides from intron 17a, which predictively cause frameshift and a premature stop codon. The use of this alternative splice site causes a reduction in the levels of normal transcripts from the allele with this mutation and, most probably, of normal protein as well. By immunocytochemistry of both epithelial primary cell cultures and slices from CF polyps, CFTR protein is detected at the cell membrane, with three different antibodies. Ussing chamber analysis of one nasal polyp shows a high sodium absorption, characteristic of CF. Altogether, the results suggest that the main defect caused by the 3272-26A-->G mutation is a reduction in normal CFTR transcripts and protein and therefore this mutation should be included in class V, according to Zielenski and Tsui.

Adolescent↗
PubMed1999

Vasoactive intestinal peptide stimulates apical secretion in hamster seminal vesicle epithelial cells in culture.

In this study, we investigated the presence of vasoactive intestinal peptide (VIP) receptors in the epithelial cells of the hamster seminal vesicle, by using cell clusters isolated from the gland and cultivated in a serum-free bicameral culture system. An immunocytochemical approach and autoradiographic and biochemical binding experiments with 125I-VIP as radioligand were performed. The effect of this neuropeptide on cultured cell proliferation and protein secretory activity was also analysed. The release of trichloroacetic-acid-precipitable radioactive material by epithelial cells to the apical and basal compartments of the bi-chamber was estimated in absolute and relative terms. The results of this work indicate that: (1) VIP receptors are present in the membranes of clusters of epithelial cells from seminal vesicles and are further maintained in cultured cells; (2) VIP does not exert any mitogenic effect in these cells; (3) VIP affects the directionality of secretion, favouring the absolute and relative amounts of protein released to the apical compartment of the bi-chamber. The expression of VIP receptors in the epithelial cells of the hamster seminal vesicle and the direct secretagogue-like activity of this neuropeptide in these cells might be affected by other factors, namely, androgens.

Animals↗
PubMed1999

Suppression of 125I-vasoactive intestinal polypeptide binding sites in arteries of the hamster seminal vesicle following castration.

The presence and distribution of 125I-vasoactive intestinal polypeptide (VIP) binding sites in blood vessels supplying the hamster seminal vesicle was studied using a receptor autoradiographic technique before and following castration. 125I-VIP binding was studied in intact animals, in animals under a 15-day period of castration and in animals under the same period of castration but submitted to a further 15-day period of testosterone treatment. Our results show that, in the seminal vesicle, VIP-binding sites are localized in the gland smooth muscle coat and arterial smooth muscle. A 15-day castration period abolishes 125I-VIP binding to vascular smooth muscle but has no effect on 125I-VIP binding to the gland smooth muscle coat. Treatment with testosterone restores 125I-VIP binding to the vascular smooth muscle, completely reversing the effect of castration. Our results indicate that VIP-binding sites in the smooth muscle wall of arteries supplying the hamster seminal vesicle are under androgenic control and are more sensitive to androgen deprivation that VIP-binding sites associated to the gland smooth muscle coat.

Animals↗
PubMed1999

Deletion of the four C-terminal residues of PepC converts an aminopeptidase into an oligopeptidase.

The aminopeptidase PepC is a cysteine peptidase isolated from lactic acid bacteria. Its structural and enzymatic properties closely resembles those of the bleomycin hydrolases, a group of cytoplasmic enzymes isolated from eukaryotes. Previous biochemical and structural data have shown that the C-terminal end of PepC partially occupies the active site cleft. In this work the substrate specificity of PepC was engineered by deletion of the four C-terminal residues. The mutant PepCDelta432-435 cleaved peptide substrates as an oligopeptidase while the aminopeptidase specificity was totally abolished. The substrate size dependency indicated that PepCDelta432-435 possesses an extended binding site able to accommodate four residues of the substrate on both sides of the cleaved bond. The activity of PepCDelta432-435 towards tryptic fragments of casein revealed a preference for peptides with hydrophobic amino acids at positions P2 and P3 and for Gly, Asn and Gln at position P1. PepCDelta432-435 was shown to be highly sensitive to the thiol peptidase inhibitors leupeptin or E64 which are inefficient towards the wild-type PepC. In conclusion, deletion of the four C-terminal residues in PepC produces a new enzyme with properties resembling those of an endopeptidase from the papain family.

Aminopeptidases↗
PubMed1997

Experimental evidence for the essential role of the C-terminal residue in the strict aminopeptidase activity of the thiol aminopeptidase PepC, a bacterial bleomycin hydrolase.

PepCs isolated from lactic acid bacteria and bleomycin hydrolases of eukaryotic organisms are strict aminopeptidases which belong to the papain family of thiol peptidases. The structural basis of the enzymic specificity of the lactococcal PepC has been investigated by site-directed mutagenesis. The deletion of the C-terminal residue (Ala-435) abolished the aminopeptidase activity, whereas this deletion led to a new peptidase specificity. The enzymic properties of wild-type and mutant PepCs demonstrate that the terminal alpha-carboxy group plays a key role in the strict aminopeptidase activity.

Alanine↗
PubMed1997

Nasopharyngeal colonization in Costa Rican children during the first year of life.

BACKGROUND: The establishment of the nasopharyngeal flora was followed in Costa Rican children from birth to 1 year of age. METHODS: Nasopharyngeal cultures were obtained at 1 (n = 413), 3 (n = 393), 6 (n = 376) and 12 months (n = 356) of age from children representative of the population in the Puriscal district. Weekly cultures were obtained from a subcohort of these children (n = 101). Mother-infant diads (n = 95) and preschool children (n = 208) attending day-care centers were also studied. RESULTS: The estimated proportion of colonized children in the population differed markedly depending on the frequency of culture. Quarterly cultures showed a slow increase in carrier rates from 3.9% for Haemophilus influenzae, 3.1% for Streptococcus pneumoniae and 6.5% for Moraxella catarrhalis at 1 month of age to 10.1% carrying H. influenzae and 19.4% carrying S. pneumoniae by the end of the first year. By quarterly culture the proportion of children colonized at least once was 36% for S. pneumoniae, 26% for H. influenzae and 28% for M. catarrhalis. In contrast weekly sampling showed that 95 to 100% of the children were colonized at least once during the first year of life with H. influenzae, S. pneumoniae or M. catarrhalis. Nasopharyngeal carriage of H. influenzae, S. pneumoniae and M. catarrhalis was low in the mothers, and very few mother-infant pairs carried identical bacteria at the same time. In contrast carrier rates were high in the siblings attending day care (H. influenzae 27.9%, S. pneumoniae 39.4%, both organisms 26.6%). Infants with siblings had significantly higher bacterial carriage at all ages than infants without siblings. CONCLUSIONS: Quarterly nasopharyngeal cultures showed that Costa Rican infants acquire their nasopharyngeal flora at a rate comparable with that for infants in developed countries and that siblings are an important source of the bacteria. Weekly samplings showed that virtually all children were colonized at least once during the first year of life.

Adult↗
PubMed1997

Interaction of mercury with human and bovine milk proteins.

The interaction of inorganic mercury with human and bovine milk proteins was studied. Gel filtration chromatography of skimmed milk and whey incubated with mercury showed that, in human milk, mercury was mainly bound to caseins, while a low proportion was bound to albumin. In bovine milk, mercury was associated with two protein fractions, caseins and beta-lactoglobulin. Furthermore, it was shown by electrophoresis that mercury induced the formation of dimers of beta-lactoglobulin. Thus, in both human and bovine milk, mercury possessed greater ability to interact with milk proteins than to the low-molecular-weight substances. However, the pattern of mercury distribution was different between the milk of these two species.

Animals↗
PubMed1996

Cadmium uptake by Caco-2 cells. Effect of some milk components.

The effect of some milk components on the cellular uptake of cadmium has been studied using a human intestinal cell line (Caco-2). Cadmium uptake by Caco-2 cells increased with the concentration of this metal in the culture medium, in a saturable way. These cells were exposed to different concentrations of cadmium and the synthesis of metallothionein was studied by a cadmium-saturation method. The levels of metallothionein increased with the cadmium concentration in the medium up to 20 microM of metal. Supplementation of the culture medium with 10% bovine milk caused a 25% decrease in the uptake of cadmium with respect to that internalized by the cells maintained in the culture medium alone. However, the uptake of cadmium from the medium supplemented with 10% human milk was similar to that with serum-free medium. beta-Lactoglobulin interacted with cadmium when studied by equilibrium dialysis, showing a stoichiometric binding constant of 5 x 10(4) l/mol. Interaction of lactoferrin with cadmium, however, was negligible. When Caco-2 cells were incubated in culture medium containing lactoferrin, cadmium uptake decreased with respect to that observed incubating the cells in a medium containing beta-lactoglobulin or in the free-protein medium. The inhibitory effect of lactoferrin on the uptake of cadmium might be due to a reduction of the cell surface charge, through its binding to the membrane.

Animals↗
PubMed1996

Immunomagnetic separation and PCR detection show Shigellae to be common faecal agents in children from urban marginal communities of Costa Rica.

Culture and immunomagnetic separation-polymerase chain reaction assays (IMS-PCR) were used to isolate and identify Shigella flexneri, S. dysenteriae type I and S. sonnei in faeces from 250 children up to 5 years and from their mothers (n = 143) selected at random from a large urban marginal community of Costa Rica. Children hospitalized because of severe diarrhoea (n = 110) were also studied. Only S. flexneri, mainly serotype 2a, and S. sonnei were found by culture. All specimens in which Shigella was cultured were also positive by the corresponding IMS-PCR. S. flexneri was isolated by culture from 1 (0.7%) mother and 4 (1.6%) community children. S. sonnei was found in 2 (0.8%) children. An additional 12 S. flexneri and four S. sonnei in the community children were found by IMS-PCR. In total, Shigella was cultured from 0.7% of mothers and 2.4% of children. By the IMS-PCR 2% of mothers and 8% of children were positive. S. flexneri was isolated by culture from 14 (12.7%) hospitalized children and S. sonnei from 1 (0.9%). An additional 11 S. flexneri and three S. sonnei were found by IMS-PCR. In total, Shigella was cultured from 13.6% of hospitalized children. By the IMS-PCR 26% of them were Shigella positive. Thus IMS-PCR was more than twice as effective in diagnosing shigellae as culture. Twelve (60%) Shigella positive community children were above 3-years-old and 25% of them were under one year. Seven (35%) of the Shigella positive children had dysenteric and 9 (45%) normal stools. Half of the Shigella infected community children had been weaned before the 3 months of age. By the age of 5 months, 90% of them were already weaned. Seventeen (59%) of the hospitalized Shigella positive children were under 1 year of age. The stools were watery or semiliquid in 13 (45%) and dysenteric in 12 (41%) of them. We conclude that shigellosis is common in Costa Rica and represents an important cause of severe infant diarrhoea requiring hospitalization.

Adult↗
PubMed1995

HIV/AIDS in Costa Rica: epidemiological and sociological features, 1993.

Acquired immunodeficiency syndrome (AIDS) was first detected in Costa Rica in 1983. For four years most known cases were in hemophiliac men. Thereafter, AIDS in homosexual and bisexual men predominated. By December 31 of 1993, 563 persons had been diagnosed with the syndrome, 71% of them homosexual and bisexual men, 10% heterosexual men and women, 6% hemophiliacs, 2% intravenous drug abusers (IVDA's), 2% women and men who had blood transfusions, 1.4% infants born to HIV-infected mothers and 7% unknown. The epidemics in homosexual/bisexual men and in heterosexual women and men are rising; cases in infants and in persons who received blood or coagulation factors, are stagnant. The steady increase in AIDS among women is linked to exposure to bisexual partners. The moderate nature of the national epidemic reflects, in part, the low incidence of IVDA, the universal screening of blood donors for antibodies to the human immunodeficiency virus (HIV) since 1985, and the prompt banning of unsafe coagulation factors. The projection of AIDS for the year 2000 is 2,304 cases (606 accumulated incidence per million inhabitants). A national educational campaign, radio and television programs and other preventive actions, apparently did not influence the rate of receptive anal intercourse without condom (about 80%) during 9 years of the epidemic. Persons with HIV/AIDS often are deprived of social and medical benefits or are subjected to harassment and exploitation by the health sector. More efficient prevention must target children, adolescents and adults in reproductive age, to promote safer lifestyles, through education and counseling effected through primary health care.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Serum antibody titres to Shigella lipopolysaccharides and invasion plasmid antigens in healthy Costa Rican and Swedish women.

Specific serum antibody titres to defined lipopolysaccharides (LPS) of Shigella spp. and Salmonella serogroup B (BO) and Shigella invasion plasmid antigens (Ipa) were determined by enzyme immunoassays in healthy Costa Rican women from low (n = 34), middle (n = 36) and high (n = 19) socioeconomic conditions and from 64 Swedish women. Specific IgG antibody titres were the highest, in particular to the S. flexneri Y LPS, with mean titres of 750 (SD = 360), 690 (380), and 820 (300) for the Low, Middle and High Costa Rican groups respectively. Lower titres were recorded against S. sonnei and S. dysenteriae type 1. Titres against Salmonella LPS were very low (< 250). In Swedish women, significantly lower serum anti-LPS titres were found (p < 0.05). No statistically significant differences regarding socioeconomic conditions or serum anti-LPS titres were seen in the Costa Rican groups (p > 0.05). Mean IgG-titres to the Ipa of 330 (150), 220 (170) and 140 (110) were found for the 3 Costa Rican groups, respectively. The IgG and IgM titres to Ipa in serum from the Low group were significantly higher than those of the High group (p < 0.05). The mean serum IgG titre of 70 (90) for the Swedish women was significantly lower than that of the Low and Middle groups (p < 0.05), but similar to that of the High group (p > 0.05). High IgG anti-Ipa titres were found in 38% from the Low, 19% from the Middle but none in the High group (mean value of the High group +2 SD).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Bacterial↗
PubMed1994

Extinction of Vibrio cholerae in acidic substrata: contaminated fish marinated with lime juice (ceviche).

Millions of Vibrio cholerae O1 El Tor were rapidly eliminated when added to commercial ceviche prepared by marination of mahi-mahi fish in lime juice. Likewise, large masses of viable vibrios present in laboratory contaminated fish, were readily eliminated after immersion in lime juice, during the preparation of ceviche. The killing effect was evident within 5 min of exposure of vibrios to lime juice, with reductions of more than 99.9% of the initial bacterial mass. After 2 h of marination of fish with lime juice (the minimum recommended), no vibrios were detected in the lowest working dilutions (1:10, 1:100). The Vibrio mass eliminated by lime juice was 2 to 6 logarithms greater than the maximum infectious dose, and 4 to 8 logs greater than the minimum infectious dose to induce cholera El Tor. Also, the killing time was shorter than the elapsing time between preparing and serving food in homes or restaurants. The traditional marination of fish with lime juice or its addition to seafood and meals immediately before consumption, should be protected and promoted to prevent infection with cholera vibrios. In the face of an epidemic of cholera, consumption of ceviche prepared with lime juice would be one of the safest ways to avoid infection with V. cholerae.

Animals↗
PubMed1994

Extinction of Vibrio cholerae in acidic substrata: contaminated cabbage and lettuce treated with lime juice.

Lime juice killed millions of Vibrio cholerae O1, El Tor, Inaba, present on cabbage and lettuce contaminated in the laboratory. The lethal effect was evident within 5 min of exposure to lime juice. No vibrios could be recovered at dilution 1:10 using alkaline peptone water (APW) and thiosulfate-citrate-bile salts-saccharose agar (TCBS). More than 99.9% of the initial inoculum was effectively destroyed. The number of vibrios killed by lime juice was 2 to 6 logarithms greater than the maximum infecting dose, and 4 to 8 logs greater than the minimum infecting dose for cholera El Tor. The time interval needed for killing was smaller than the usual waiting time for serving food in homes and restaurants. The addition of lime juice to non-acidic foods, beverages and water, is strongly recommended to prevent infection with cholera vibrios and other acid-sensitive microorganisms. This measure is particularly important for rural and slum populations in the tropics and subtropics.

Cholera↗
PubMed1993

[Echo Doppler in abdominal aortic dissection].

The authors present a case of abdominal aorta dissection--type B. The diagnosis was made by Doppler ultrasound and computerized tomography (CT). The use of Doppler ultrasound in the diagnosis and assessment of abdominal aorta dissection and visceral arterial involvement is discussed. Doppler ultrasound is also a useful imaging technique in follow-up evaluation if conservative treatment is employed.

Aortic Dissection↗
PubMed1992

Titres of class-specific antibodies against Shigella and Salmonella lipopolysaccharide antigens in colostrum and breast milk of Costa Rican, Swedish and Vietnamese mothers.

Enzyme immunoassays (EIA) were used to estimate titres of class-specific antibodies against purified and chemically defined phenol-water-extracted lipopolysaccharide (LPS) antigens of Salmonella serogroup B (BO), Shigella dysenteriae type I, Plesiomonas shigelloides (the same O-antigen as Shigella sonnei) and Shigella flexneri Y. Titres in colostrum and breast milk of Swedish, Vietnamese and Costa Rican mothers from various socioeconomic conditions were compared. The antibodies were mainly of the IgA isotype. IgM antibodies were also present, but only very low concentrations of IgG were found. In Costa Rican mothers, the IgA antibody titres were significantly higher (P less than 0.05) in women of low and middle socioeconomical conditions than were those in mothers of high socioeconomical level. The low titres in the last group were comparable to those found in Swedish mothers. The IgA antibody titres found in Vietnamese mothers were similar to those of Costa Rican mothers from the low and middle socioeconomic conditions, being highest against S. flexneri Y LPS. The IgM antibody titres were also highest in Vietnamese mothers, immediately followed by the Costa Rican mothers of low socioeconomic conditions. The low IgM titres in the Costa Rican women of high socioeconomic level were comparable to those seen in Swedish mothers. The results suggest that, in Costa Rica and Vietnam, S. flexneri is the most prevalent Shigella sp. causing infection and that Salmonella serogroup B infections are rare in all three countries. The results also show that the antibody repertoire in colostrum and breast milk varies. Furthermore, in addition to the prevalence of a specific micro-organism in a determined geographical area, such differences may be associated mainly with exposure to certain pathogens in particular socioeconomic conditions.

Adult↗