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C Barrera

Publications and source records attributed to C Barrera.

At least 19 recordsLinked to original sources
PubMed2001

Expression of cathepsins B, L, S, and D by gastric epithelial cells implicates them as antigen presenting cells in local immune responses.

Helicobacter pylori infection is linked to chronic gastritis, peptic ulcer and gastric carcinoma. During H. pylori infection, class II MHC expression by the gastric epithelium increases, as does the number of local CD4(+) T cells, which appear to be important in the associated pathogenesis. These observations suggested that the epithelium might present antigens to T cells. Thus, we sought to determine whether gastric epithelial cells process antigens to establish their function as local antigen presenting cells (APC). We examined a panel of gastric epithelial cell lines for expression of the antigen processing cathepsins B (CB), L (CL), S (CS), and D (CD). The mRNA for these enzymes were detected by RT-PCR and the enzymes in the gastric epithelial cells were identified by various independent methods. We corroborated the expression of CB and CD on gastric epithelial cells from human biopsy samples. The functions of these proteases were confirmed by assessing their ability to digest ovalbumin, a conventional dietary antigen, and proteins from H. pylori. In summary, multiple lines of evidence suggest gastric epithelial cells process antigens for presentation to CD4(+) T cells. To our knowledge, these are the first studies to document the antigen processing capacity of human gastric epithelial cells.

Antigen Presentation↗
PubMed1999

Internal carotid artery transposition: another cause of widening of the retropharyngeal space.

We present four cases of internal carotid artery (ICA) transposition which caused widening of the retropharyngeal soft tissues. Internal carotid artery transposition is a rare cause of retropharyngeal space enlargement, which can be accurately diagnosed in a non-invasive manner with spiral CT. Radiologists should be aware of this entity in the differential diagnosis of retropharyngeal space enlargement in symptomatic (dysphagia, pulsatile mass) and asymptomatic patients, and alert the clinician of its existence, due to the risk of massive bleeding if neck surgery is to be performed.

Aged↗
PubMed1999

Genetic analysis of leishmania parasites in Ecuador: are Leishmania (Viannia) panamensis and Leishmania (V.) Guyanensis distinct taxa?

In the course of an epidemiologic survey in Ecuador, the following collection of Leishmania stocks was isolated: 28 from patients with clinical signs of leishmaniasis, 2 from sloths, 1 from a dog, and 4 from sand flies. For genetic characterization of these stocks, multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) were used. Twenty six of the 35 stocks were identified as either Leishmania (V.) panamensis or L. (V.) guyanensis, 2 stocks were identified as L. (V.) braziliensis, the 2 stocks from sloths showed specific genotypes, and 5 stocks were characterized as hybrids between L. (V.) braziliensis and L. (V.) guyanensis. These data show that genetic diversity of Leishmania in Ecuador is high and that L. (V.) panamensis/guyanensis is the dominant group in this country. The genetic analysis questioned the distinctness between the two species L.(V.) panamensis and L. (V.) guyanensis, since MLEE and RAPD data did not indicate that L. (V.) panamensis and L. (V.) guyanensis correspond to distinct monophyletic lines. Population genetic analysis performed on the L. (V.) panamensis/guyanensis group favors the hypothesis of a basically clonal population structure.

Animals↗
PubMed1997

Expression of B7-1 and B7-2 costimulatory molecules by human gastric epithelial cells: potential role in CD4+ T cell activation during Helicobacter pylori infection.

Human gastric mucosal epithelial cells display class II MHC, the expression of which is increased during Helicobacter pylori infection. These observations suggest that the gastric epithelium may participate as antigen-presenting cells (APC) during local immune responses. The increase in class II MHC expression occurs in parallel with an elevation in gastric CD4+ T cell numbers within and adjacent to the epithelium. Since the expression of either B7-1 (CD80) or B7-2 (CD86) on APC is required for the activation of T cells, it was important to establish human gastric epithelial cells expressed those surface ligands. The expression of B7-1 and B7-2 was detected on human gastric epithelial cell lines and freshly isolated epithelial cells from gastric biopsies with specific antibodies. B7-2 expression was higher than B7-1 at both protein and transcript levels and was increased after crosslinking class II MHC molecules on IFNgamma-treated epithelial cells and in cells pretreated with the combination of IFNgamma and H. pylori. Similarly, B7-2 expression was higher on gastric epithelial cells from H. pylori-infected tissues compared with those from uninfected specimens. To determine the function of these molecules on gastric epithelial cells, antibodies to B7-1 and B7-2 were shown to reduce the ability of the cells to stimulate alloreactive CD4+ T cells. These observations are the first to demonstrate that B7-1 and B7-2 are expressed on mucosal epithelial cells in situ. Thus, the expression of B7-1 and B7-2 by epithelial cells may allow them to act as APC in regulating local responses such as those that occur during infection with H. pylori.

Antigens, CD↗
PubMed1995

A simple method to detect sperm chromatin abnormalities: cytochemical mechanism and possible value in predicting semen quality in assisted reproductive procedures.

Protamine crosslinking by disulphide (-SS-) bonds in the main factor responsible for the stability of chromatin structure in mammalian spermatozoa. Sperm chromatin containing arginine/cysteine-rich protamines shows a deeply modified cytochemical reactivity (e.g. basophilia) when compared with somatic chromatic. After methanol or ethanol-acetic acid fixation and toluidine blue (TB) staining, most sperm heads in semen smear from human fertile donors exhibited a pale blue (orthochromatic) colour, while a few sperm heads exhibited violet-blue or violet (metachromatic) staining. Smears from infertile patients showed an increased amount of metachromatic sperm nuclei. After reduction of -SS- bonds by dithiothreitol, sperm heads from all smears were metachromatic, suggesting that DNA phosphates then become available for TB stacking. Micro- and macro-spectrophotometric studies confirmed the microscopic colour reaction of sperm nuclei. The ortho-/metachromatic ration seems a useful parameter for evaluation of altered chromatin structure in spermatozoa cells. Taking into account the current interest in complementary staining tests for evaluation of semen quality, the metachromatic TB reaction represents a simple cytochemical approach for detecting sperm chromatin abnormalities based on differences in -SS- crosslinking.

Chromatin↗
PubMed1994

[Eclampsia: 8-year experience].

Eighty-one cases of eclampsia were managed from april 1985 to may 1993 with an incidence of 1.0 in 1.000 deliveries, at the Department of Obstetric, Gynecology and Neonatology of Barros Luco-Trudeau Hospital, Santiago, Chile. 84.6% of patients were primipara and 45.7% were less than 20 years of age. Convulsions occurred during pregnancy in 61.7% of patients, during labor 22.2% and 16.1% post partum. Eleven cases (13.6%) had convulsions while receiving magnesium sulfate therapy. Prior to convulsion 21.3% of patients showed blood pressure below 140/100 mmHg. 25.9% of patients had normal urine protein. Cesarean section was performed in 75.3%, and the most frequent indication was poor cervical conditions. Fetal distress respiratory and the intrauterine growth retardation were the most frequent neonatal morbidity. Perinatal mortality was 13.2%. Maternal mortality was 3.7%.

Adolescent↗
PubMed1994

[Leishmaniasis in Ecuador. 1. Incidence of cutaneous leishmaniasis on the Pacific coast].

A clinico-epidemiologic survey on cutaneous leishmaniasis, due to Leishmania panamensis, was carried out on 961 persons in two study areas of the Pacific coast of Ecuador, to estimate the prevalence and the incidence of the disease. In the preandean hills, at Paraiso Escondido, the prevalence of active lesions was 4.8%; in the hills of the coastal cordillera, at La Tablada, it was 3.6%. The incidence of new cases in 1991 was high: 147% in the first village, and 106% in the second. These data are far higher than the Health Ministry statistics. The cumulated prevalence, obtained by addition of the scars and active lesions of leishmaniasis, was as high as 66% at Paraiso Escondido, and 47% at La Tablada. Most of the patients (62%) had only one ulcer or scar. Most of the people are contaminated during the first five years they live in these endemic areas. Nevertheless, the incidence remains high in all the age groups, because large numbers of migrants coming from non endemic regions are continuously settling in these colonization areas. Interviews have shown that the contaminations had occurred in the dry season, between July and December. These findings were confirmed by passive case detection at the Hospital A. Egas of Santo Domingo which covered the region. Contamination of young children and position of the lesions on the face suggested a domiciliary transmission, like in Panama and on the Pacific coast of Colombia.

Adult↗
PubMed1994

[Leishmaniasis in Ecuador. 4. Natural infestation of the dog by Leishmania panamensis].

In two endemic leishmaniasis foci of the Pacific coast of Ecuador 34 dogs suspected of having the disease have been surveyed clinically, serologically and parasitologically; immunofluorescence and electrosyneresis tests, lymph node aspirates, biopsies and smears have been performed. From two dogs with ulcers only one had ulcers on the muzzle and the scrotum infected by Leishmania (L. guyanensis complex). The isolated strain was identified as Leishmania panamensis. The disease was strictly cutaneous. In the study area the dog seems to be more a victim-host than a reservoir.

Animals↗
PubMed1994

[Leishmaniasis in Ecuador. 6. Epidemiological and entomological note on the focus of leishmaniasis in Zumba].

The Zumba focus of tegumentary leishmaniasis lies in the southwards Amazonian region of Ecuador. A clinico-epidemiological study has been carried out in the area on 83 patients attending health centers. All the biotopes suitable for sandflies, including dwellings, have been sampled from February to September 1992 by light trap and human bait catches. The number of sandflies caught amounts to 2,547. Anthropophilic sandfly fauna is poor and only three species have been recorded. Lutzomyia serrana abounds inside dwellings where it bites men even during daytime. The parasite was identified as an intermediate form between Leishmania panamensis and L. braziliensis. It will be described elsewhere. The high proportion of facial lesions suggests a domiciliary transmission for which Lu. serrana could be a good vector candidate.

Adolescent↗
PubMed1993

Metachromatic staining of human sperm nuclei after reduction of disulphide bonds.

Intra- and interprotamine cross-linking by disulphide bonds are the main factors responsible for the highly compact and stable structure of chromatin in mammalian spermatozoa. Unfixed or methanol fixed smears of human sperm and sperm suspensions from fertile donors and oligospermic patients were subjected to a reductive cleavage of disulphide bonds by using 2-mercaptoethanol (ME) or dithiothreitol (DTT). Untreated (control) and ME or DTT treated samples were stained with toluidine blue (TB) and examined in light microscopy; spectral characteristics of TB stained sperm nuclei were also analyzed. Untreated smears from fertile donors showed an orthochromatic (pale blue) staining of most sperm heads, while a variable proportion of metachromatic nuclei was found in spermatozoa from patients with oligospermia. After treatment with DTT followed by TB staining, fixed and unfixed smears showed metachromatic sperm heads. ME treatment only induced a scarce colour shift, whereas a striking metachromatic reaction and variable nuclear swelling were observed in DTT treated sperm suspensions. These results indicate that after cleavage of disulphide bonds, phosphate groups from chromatin DNA are unmasked and available for TB binding and metachromatic staining.

Cell Nucleus↗
PubMed1991

[Myocardial infarction and pregnancy].

We show a clinic case of a female patient 42 years old that suffered a myocardial infarction by coronary spasm, while she was in her 30th and a half weeks of gestation. We analyze the bases of the diagnostic its evolution and the neonatal complications.

Adult↗
PubMed1991

[Spontaneous liver rupture in pregnancy-induced hypertension].

Spontaneous rupture of liver during pregnancy is associated with a very high maternal mortality. This lesion is an unusual complication of the preeclampsia-eclampsia syndrome. We report the case of a 34 years old woman who suffered this complication; responding satisfactorily after conservative surgical treatment.

Adult↗
PubMed1989

[Role of the immune response in male infertility].

In guinea pigs using testis homogenate with Complete Freund's Adjuvant as antigen, a close correlation between cellular immunity (CI) and orchitis injury was found. High titres of antisperm cytophilic antibodies (ACA) were found in serum simultaneously with gonadal lesions. Cytotoxic effects of ACA were investigated using a purified eluate of the antibody from macrophage surfaces and injecting it by subalbuginea route or incubating it with germinal cells or spermatozoa. The IgG2 nature of ACA was demonstrated by immunochemical techniques. Specific studies showed that the cytotoxic effect was not due to immune complexes. Ultrastructural studies of macrophage-ACA-spermatozoa complex by scanning and transmission electron microscopy showed the different stages of ACA-mediated sperm phagocytosis. "Thermal orchitis" was developed in guinea pigs as a model to induce orchitis without adjuvant. Isolation and identification of the sequential cell populations in the granuloma showed macrophages as the main cell type. T cells were seen to increase while B cells decreased and were substituted by plasma cells. Potentiality of unilateral sperm cord torsion for autosensitization against the other gonad was studied; orchiectomy of the injured gonad prevented the orchitis lesion and avoided the immune response. Infertile men were studied immunologically. Patients with genital infection or sperm duct obstruction exhibited positive antisperm autoimmunity tests. Cl alterations were detected early and persisted for many years, while humoral antisperm antibodies were not detected during more than two years. Azoospermic patients showed autosensitization in 50% of the cases. Finally, Percoll gradients were used to isolate and identify non spermatic round cells from semen samples of asthenozoospermic men.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Economic development and occupational health in Latin America: new directions for public health in less developed countries.

Occupational Health is increasingly recognized as an area of importance in Latin American public health. In the agricultural sector of the region, the concentration of arable land into large holdings devoted to the production of export crops has resulted in the formation of a large migrant work force and greatly increased use of pesticides. The manufacturing sector of Latin America has grown rapidly in size and importance. Throughout the continent, increasing numbers of workers are employed in high-hazard industrial jobs. Limited studies of occupational disease in agriculture, mining, and manufacturing suggest that there is a high prevalence of work-related illness in the populations at risk. Trade unions are generally weak, and the high rate of unemployment and underemployment render occupational health a low priority for many workers. Engineering controls and personal protective equipment are unknown or inadequate in many industries, and there is a shortage of trained occupational health professionals in the region. Steps are being taken by many Latin American governments to begin to address this problem. Needed are: increased worker and professional training; a uniform set of exposure standards; control of multinational marketing and usage of hazardous substances; the development of technical equipment appropriate for local use and increased research on occupational exposure in populations in less developed countries.

Adolescent↗
PubMed1984

Correlation of immune complexes with serum cytotoxic activity induced by antisperm cytophilic antibodies.

The object of the present work was to investigate: a) The cytotoxic activity of cytophilic antibody in sera from guinea pigs sensitized with the testicular antigen; b) The presence of immune complexes. In vitro cytotoxicity induced by hyperimmune sera or by the cytophilic antibodies eluted from the corresponding macrophages, was demonstrated after incubation with either germinal cells or spermatozoa. Marked cytotoxicity was also observed in vivo when sera or antibodies were injected into the tests, as shown by sequential histologic studies. Circulating immune complexes, as tested by the 125I-C1q binding assay, were not detected in these sera. On the contrary, high levels of circulating immune complexes were found when the polyethyleneglycol precipitation test was used. It can be concluded that the cytotoxic effect induced by cytophilic antibodies of IgG2 nature, may be associated with polyethyleneglycol precipitating immune complexes.

Animals↗