Structural properties of lipid reconstructs and lipid composition of normotensive and hypertensive rat vascular smooth muscle cell membranes

Multiple cell membrane alterations have been reported to be the cause of various forms of hypertension. The present study focuses on the lipid portion of the membranes, characterizing the microviscosity of membranes reconstituted with lipids extracted from the aorta and mesenteric arteries of spontaneously hypertensive (SHR) and normotensive control rat strains (WKY and NWR). Membrane-incorporated phospholipid spin labels were used to monitor the bilayer structure at different depths. The packing of lipids extracted from both aorta and mesenteric arteries of normotensive and hypertensive rats was similar. Lipid extract analysis showed similar phospholipid composition for all membranes. However, cholesterol content was lower in SHR arteries than in normotensive animal arteries. These findings contrast with the fact that the SHR aorta is hyporeactive while the SHR mesenteric artery is hyperreactive to vasopressor agents when compared to the vessels of normotensive animal strains. Hence, factors other than microviscosity of bulk lipids contribute to the vascular smooth muscle reactivity and hypertension of SHR. The excess cholesterol in the arteries of normotensive animal strains apparently is not dissolved in bulk lipids and is not directly related to vascular reactivity since it is present in both the aorta and mesenteric arteries. The lower cholesterol concentrations in SHR arteries may in fact result from metabolic differences due to the hypertensive state or to genes that co-segregate with those that determine hypertension during the process of strain selection.

Glycosphingolipid antigens from Leishmania (L.) amazonensis amastigotes. Binding of antiglycosphingolipid monoclonal antibodies in vitro and in vivo

Specific glycosphingolipid antigens of Leishmania (L.) amazonensis amastigotes reactive with the monoclonal antibodies (MoAbs) ST-3, ST-4 and ST-5 were isolated, and their structure was partially elucidated by negative ion fast atom bombardment mass spectrometry. The glycan moieties of five antigens presented linear sequences of hexoses and N-acetylhexosamines ranging from four to six sugar residues, and the ceramide moieties were found to be composed by a sphingosine d18:1 and fatty acids 24:1 or 16:0. Affinities of the three monoclonal antibodies to amastigote glycosphingolipid antigens were also analyzed by ELISA. MoAb ST-3 reacted equally well with all glycosphingolipid antigens tested, whereas ST-4 and ST-5 presented higher affinities to glycosphingolipids with longer carbohydrate chains, with five or more sugar units (slow migrating bands on HPTLC). Macrophages isolated from footpad lesions of BALB/c mice infected with Leishmania (L.) amazonensis were incubated with MoAb ST-3 and, by indirect immunofluorescence, labeling was only detected on the parasite, whereas no fluorescence was observed on the surface of the infected macrophages, indicating that these glycosphingolipid antigens are not acquired from the host cell but synthesized by the amastigote. Intravenous administration of 125I-labeled ST-3 antibody to infected BALB/c mice showed that MoAb ST-3 accumulated significantly in the footpad lesions in comparison to blood and other tissues.

Isolation and possible composition of glucosylceramides from Paracoccidioides brasiliensis

Twelve different species of neutral monohexosyl ceramides (CMHs) and two species of neutral monohexosyl ceramides were isolated form mycelium and yeast forms of Paracoccidioides brasiliensis, respectively, by a combination of ion-exchange chromatography, HPLC, and HPTLC. The glucosylceramides did not react with sera from patients with paracoccidioidomycosis (PCM). Carbohydrate analysis indicated that CMHs contain glucose. Analysis of (1)H-NMR and mass spectrometry data suggest that the structure of the CMHs is Glcpbeta1(Cer (mycelium forms present 12 different ceramides and yeast forms present 2 different ceramides). The composition of the lipid moieties was analyzed by negative fast atom bombardment mass spectrometry. No glycosphingolipid other than glucosylceramide was detected in P. brasiliensis.

Immunochemical characterization of carbohydrate antigens from fungi, protozoa and mammals by monoclonal antibodies directed to glycan epitopes

Cell surface carbohydrates constitute the major antigenic determinants of fungi and protozoa. Glycoconjugates also represent a large variety of antigens or markers present in mammals such as histo-blood groups ABO, differentiation and heterophile antigens, among others. This article focuses on the general properties of glycoconjugate antigens and production and characterization of the anti-carbohydrate monoclonal antibodies (MoAbs). It describes the specificity and some properties of monoclonal antibodies directed against carbohydrate epitopes present in tumor-associated glycoproteins, in clycosaminoglycans of higher eukaryotes and in glycolipid antigens of protozoa and fungi. The epitopes recognized by the anti-carbohydrate MoAbs range from one sugar unit up to ten sugar units. Although most anti-carbohydrate MoAbs are directed predominantly toward terminal sugar residues, a few MoAbs are also reactive with internal sugar residues. The fine structure of the carbohydrate epitopes has been chemically defined by [H]NMR, GC/MS of alditol acetates of partially permethylated compounds, FAB/MS, degradation with exoglycosidases and inhibition with different methyl-glycosides and oligosaccharides.

Confirmación serológica de Escherichia coli enteropatógena / Serological confirmation of enteropathogenic Escherichia coli

En nuestro país, los serotipos enteropatógenos de ESCHERICHIA COLI (ECEP) están entre los agentes bacterianos más frecuentemente asociados a cuadros diarreicos en lactantes. Se estudió mediante titulación el grado de confirmación serológica de la técnica directa en lámina en 138 cepas de ECEP aisladas de niños menores de 2 años, 80 cepas (58%) provenían de casos de diarrea y 58 (42%) de controles. Se ratificó sólo a aquellos serotipos cuyos títulos fueron >= 1:320 (antisueros Difco). La confirmación fue del 76,2% para las cepas provenientes de diarrea y del 65,5% para las de los controles. 6 serogrupos (055,0111,0119,0128,0113,020ab) fueron siempre confirmados, entre ellos se encuentran algunos de los más frecuentemente aislados en nuestro país. Los serogrupos 0127, 0112ac, 0125, 086, provenientes tanto de diarreas o controles, no fueron confirmados. En situación intermedia quedaron 6 serogrupos, destacando 0,44, 0126 y 028. Estos resultados indican la necesidad de que todos los laboratorios integren como técnica habitual la titulación en tubo para evitar "falsos positivos" en la serotipificación de EPEC

Aislamiento de Campylobacter fetus sub-especie jejuni en pollos broiler. / Isolation of Campylobacter fetus subspecie jejuni in broiller chickens

Campylobacter fetus subespecie jejuni (CFJ), reconocido como enteropatogeno para el hombre ha sido aislado tambien de mamiferos y aves.Se investigo, con metodos bacteriologicos apropiados, la presencia de CFJ en muestras obtenidas de la cloaca de 51 pollos Broiler (25 faenados y 26 vivos), provenientes de diferentes criaderos de Santiago. Se aislo CFJ en 46 muestras (90%) correspondiendo 25 aves vivas (96%) y a 21 aves faenadas (84%). La sensibilidad in vitro a antibioticos fue estudiada en 29 cepas. El 100% de ellas fue sensible a los aminoglucosidos y al cloramfenicol. En cambio, el 13,8% resulto resistente a eritromicina y el 100% a cefalosporina. Este alto porcentaje de aislamiento de CFJ en pollos aumenta la necesidad de estudios epidemiologicos sobre infeccion en el hombre, como de investigaciones sobre su posible papel patogenico en aves