Search PubMed⌕ Search

Biomedical subjects

M A Bosch

Publications and source records attributed to M A Bosch.

36 records · Page 2Linked to original sources
PubMed1993

Visualization of lipopolysaccharide aggregates by freeze-fracture and negative staining.

The morphology of Escherichia coli 0111:B4 lipopolysaccharide (LPS) in aqueous medium was studied by freeze-fracture and negative staining. Samples processed by freeze-fracture showed LPS aggregates that were mainly spherical or elliptical and of rather homogeneous size. Negative staining, however, showed a more heterogeneous population, although globular structures revealed by both procedures had a similar size. Considering the mechanisms involved in the processing of the samples, we suggest that the genuine shape of LPS aggregates is more likely to be globular, thus being artefactual those forms visualized by negative staining, traditionally associated with the organization of LPS in aqueous suspension.

Escherichia coli↗
PubMed1993

[Frequency of platelet alloantigens in the Spanish population].

PURPOSE: The aim of this study is to investigate the distribution and incidence of platelet alloantigens in Spain and to compare this frequency with that found in other populations. MATERIAL AND METHODS: Five hundred blood donors were phenotyped for the HPA-1a (Zwa), HPA-3a (Bak(a)), HPA-4a (Yukb/Pen(a)) y HPA-4b (Yuk(a)). One hundred of these donors were also phenotyped for the HPA-5a (Br(a)) antigen. Furthermore, we also phenotyped a group of 50 black individuals from a community of west African immigrants who live in the province of Barcelona. The typing of all the antigens except those of the HPA-5 system was carried out using the technique of Indirect Immunofluorescence. To type the antigens of the HPA-5 system the MAIPA technique was employed. RESULTS AND CONCLUSIONS: The incidence of the different platelet specific antigens in the Spanish population is, in general, the same as that detected in the other European countries and in the white population of the USA. In Europe and North America, the HPA-1a antigen is the most important of all owing to its involvement in alloimmune clinical disorders. In Asia, this role seems to be played by the HPA-4b antigen. Moreover, polymorphism for the HPA-1a allele does not seem to exist. The incidence of the HPA-5b (Br(a)) antigen in Spain, which is higher than that for France and Germany, suggests a high involvement of this antigen in our country in different alloimmune processes. The preliminary data obtained in a group of black west Africans suggest the absence on polymorphism for the HPA-1a allele and that the incidence of the remaining antigens is comparable to that of the Spanish population.

Africa, Western↗
PubMed1991

Uptake and subcellular distribution of Escherichia coli lipopolysaccharide by isolated rat type II pneumocytes.

Treatment of isolated rat Type II pneumocytes with Escherichia coli lipopolysaccharide (LPS) induces a number of ultra-structural changes which become evident after 60 min of incubation. By using post-embedding immunolabeling methods and electron microscopy, we have followed the fate of LPS after different times of incubation. After an initial period of accumulation in the pneumocyte microvilli, the LPS molecules enter the cytoplasm, forming discrete patches which are dispersed in some areas. After longer incubation times, LPS localize in condensed chromatin-free areas inside the nuclei. LPS micelles were visualized after freeze-fracture and compared with the LPS-labeled membrane areas, showing that LPS micelles aggregate in particular membrane zones. The sugar-specific staining in microvilli areas, where Maclura pomifera agglutinin (MPA)-gold particles bind, indicates the presence of galactose derivatives in these membrane structures. Pre-treatment of pneumocytes with LPS inhibited the MPA-gold labeling, suggesting a relation between the MPA receptor and a possible LPS receptor. Finally, double immunolabeling experiments indicated an apparent LPS-tubulin association in some particular membrane regions, which could not be observed when LPS and actin were co-localized.

Animals↗
PubMed1990

Effect of Escherichia coli lipopolysaccharide on phosphatidylcholine biosynthesis by rat lung and alveolar type II cells.

Alterations in pulmonary surfactant are partly responsible for the respiratory insufficiency seen under septic shock process. We have used an experimental model of LPS-induced shock in rats to examine the cells responsible for the pulmonary surfactant synthesis and its relationship to lung injury. (14C)Choline incorporation into phosphatidylcholine was significantly reduced in lung homogenates or type II cells obtained from LPS-treated animals. Addition of LPS in vitro fails to increase (14C)choline incorporation in type II cells obtained from LPS-treated animals. We suggest that this depression of pulmonary phosphatidylcholine synthesis may partly explain the occurrence of respiratory failure with septic shock.

Animals↗
PubMed1990

Morphological studies of cytotoxic lesions in reversible endotoxic shock.

Reversible endotoxic shock was induced in adult rats by intravenous injection of E. coli 0111:B4 lipopolysaccharide (LPS) and the progression of metabolic and morphological alterations was evaluated. Serum samples and biopsies from adrenal gland, liver and lung were studied at different times after LPS injection. Histological changes in these tissues were observed after endotoxin administration, coinciding with both the acute-phase and the recovery-phase of shock (24-72h after LPS injection). Signs of tissue regeneration can be correlated with the regression of some serum parameters to their normal values. All these results indicate that in this experimental model of endotoxic shock, a reversible status was established, which will allow further studies of the endotoxic pathophysiological mechanisms in vivo, avoiding the complexity of the non-reversible process.

Adrenal Glands↗
PubMed1989

Effects of ovariectomy on GnRH mRNA, proGnRH and GnRH levels in the preoptic hypothalamus of the female rat.

Experiments were carried out to investigate the effects of ovariectomy on gonadotropin-releasing hormone (GnRH) messenger RNA (mRNA), proGnRH and GnRH peptide levels in the hypothalamus of female rats. Intact proestrous female rats and female rats, which had been ovariectomized for 2 weeks, were sacrificed at 9.00 h and the preoptic area (POA) and basal hypothalamus (BH) were dissected out and frozen on dry ice. One group of tissues from proestrous control and ovariectomized females were extracted in acetic acid, centrifuged at 13,000 g and the supernatant purified on a C18 column. The purified extract was then radioimmunoassayed for proGnRH, using a specific antiserum to rat proGnRH (ARK-2), and for GnRH using the E1-14 antiserum. Total cellular RNA was isolated from another group of tissues and prepared as Northern blots. Hybridization with 32P-labeled GnRH cRNA was used to detect GnRH mRNA. A third group of proestrous and ovariectomized female rats were perfused, and 50 microns vibratome sections were cut. These were immunostained with proGnRH or GnRH antiserum, followed by in situ hybridization with 35S-labeled GnRH cRNA to detect GnRH mRNA. Based on the histochemical staining, mRNA was colocalized to the cell soma of neurons containing proGnRH and GnRH throughout the POA and BH. Based on the radioimmunoassay, proGnRH levels were 2 times higher in the POA versus the BH, but GnRH levels were 6-7 times higher in the BH. Ovariectomy significantly decreased proGnRH levels in both the POA and BH, while GnRH decreased in the BH. In contrast, quantitative Northern blot analysis demonstrated that ovariectomy had no effect on mRNA levels in the POA and BH. These data indicate that the effects of ovariectomy on proGnRH and GnRH levels are a result of altered translation, posttranslational processing and/or secretion of GnRH.

Animals↗
PubMed1989

Acute erythroblastic leukemia. Cytological, cytogenetic and phenotypic studies in one case.

We report the clinical, cytological, immunophenotypic, and cytogenetic findings in one patient with acute erythroblastic leukemia. Blast cells were identified by their reactivity with the early erythroid antibodies FA6-152 and carbonic anhydrase I. The leukemic blasts had no specific differentiating features identifying them as erythroblasts even at an ultrastructural level. Cytogenetic studies revealed multiple chromosome aberrations: 45,XX,i(11q),-16,-17,-21,+der(21)t(21;?)(q22;?),+mar 1.

Aged↗
PubMed1988

Induction of reversible shock by Escherichia coli lipopolysaccharide in rats. Changes in serum and cell membrane parameters.

Reversible endotoxic shock was induced in adult rats by i.v. injection of Escherichia coli O111:B4 lipopolysaccharide (1.6 mg/100 g). The shock progression was evaluated by measuring serum glucose levels as well as activities of aspartate aminotransferase (GOT) and alkaline phosphatase in serum. A rapid increase of serum glucose levels occurs, after LPS injection, followed by hypoglycaemia (minimum values at 6 h) with progressive reversion to control values. Serum GOT activity increased (twofold) 6 h after endotoxin administration and returned to control values at 72 h. No appreciable changes occurred in serum alkaline phosphatase activity. Endotoxaemia produced a decrease in the cytochrome P-450 levels in all target organs considered: lung, adrenal glands and liver. The progressive decrease in the serum albumin concentration as well as changes of the physical properties of the plasma membranes observed in vivo, can not be explained only by direct interaction of endotoxin with the target organs, underlining the importance of serum mediators in the induction of the shock response.

Adrenal Glands↗
PubMed1987

Direct and mediated Escherichia coli lipopolysaccharide action in primary hepatocyte cultures.

The biphasic behaviour observed in endotoxin-induced shock attributed to a direct interaction of bacterial lipopolysaccharides with the cell membrane and an indirect activation of multiple homeostatic regulatory mechanisms, cannot be completely elucidated with in vivo studies. In primary cultures of adult rat hepatocytes, lipopolysaccharide from Escherichia coli 0111:B4 affects the cytochrome P450 levels directly; however, albumin and aspartate aminotransferase secretion are induced by some mediators present in the sera of animals in acute-phase shock.

Aminolevulinic Acid↗
PubMed1985

Influence of E. coli lipopolysaccharide binding to rat alveolar type II cells on their functional properties.

The interaction between lipopolysaccharide from E. coli 0111:B4 and rat alveolar type II pneumocytes and its influence on the functional properties of the cells and their membranes were studied. Type II cells were isolated by a novel procedure involving digestion of the lung connective tissue with elastase and Percoll-gradient centrifugation. Binding of (14C)lipopolysaccharide to type II cells resulted in a partially reversible; non-specific, high affinity process. (14C)Choline incorporation into phosphatidylcholine by type II cells was stimulated by lipopolysaccharide, the maximum effect being observed at 10-20 micrograms/ml. 45Ca2+ uptake by type II cells was also increased by lipopolysaccharide. Using plasma membranes from lung homogenates an increase of membrane microviscosity versus the amount of lipopolysaccharide was shown. These results indicate that E. coli lipopolysaccharide interacts with alveolar type II cells by binding reversibly to particular ingredients of the membrane bilayer and induces a modification of ion permeability and fluidity of the membrane.

Animals↗
PubMed1976

Age differences in the positional distribution of phosphoglycerides and molecular species of choline phosphoglycerides during development of the chick embryo liver.

The total fatty acid composition and the distribution of acyl groups in the positions 1 and 2 of 1,2-diacyl-sn-glycero-3-phosphocholine and 1,2-diacyl-sn-glycero-3-phosphoethanolamine as well as in the molecular species of 1,2-diacyl-sn-glycero-3-phosphocholine from the chick embryo liver have been investigated at various stages of development. The fatty acid content of the main lipid classes from the yolks was also evaluated. The relative percentages of total saturated fatty acids in 1,2-diacyl-sn-glycero-3-phosphocholine remained constant during liver development; however, the levels of both main saturated acids, palmitic and stearic acids, were reciprocally counterbalanced as the age of the embryo proceeded. On the other hand, arachidonic acid decreased with time whereas linoleic acid and docosahexaenoic acid doubled their proportions during development. The relative amounts of total saturated fatty acids from liver 1,2-diacyl-sn-glycero-3-phosphoethanolamine were also constant during all stages of development; however, palmitic/stearic acid ratio did not change with time in this phosphoglyceride. Fatty acid composition of the yolk phosphoglycerides did not change during embryonic development. It should be noted that marked differences between fatty acid composition of choline and ethanolamine phosphoglycerides from the embryo liver and those of the yolk phosphoglycerides were demonstrated. The general patterns of the positional distribution of the acyl groups in choline phosphoglycerides differed from those of ethanolamine phosphoglycerides. Palmitic and stearic acids were only positioned at position 1 in 1,2-diacyl-sn-glycero-3-phosphoethanolamine whereas both fatty acids did not acylate exclusively the position 1 in 1,2-diacyl-sn-glycero-3-phosphocholine.

Animals↗
PubMed1970

A field on Che.

Explore the source record for details and available documents.

Argentina↗