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E Freymuller

Publications and source records attributed to E Freymuller.

11 recordsLinked to original sources
PubMed2006

Intercellular junctions in rabbit eye ora serrata.

Summary The aim of this study was to describe and localize the intercellular junctions in the ora serrata region of albino and pigmented rabbit eyes. Eyes of albino and pigmented rabbits were fixed and processed for transmission electron microscopy. Light and electron microscope examination was carried out on semithin and ultrathin sections. The ora serrata region showed adherens, gap and tight junctions in the retinal and ciliary margins of albino and pigmented rabbit eyes. In the retinal margin, zonulae adherens between Müller cells and photoreceptors are associated with tight junctions. In the ciliary margin, epithelial cells are joined by adherens, gap and tight junctions localized between apical and apicolateral cell membranes. Tight junctions appear as zonulae occludens in the non-pigmented apicolateral cell membranes and as tight focal junctions between pigmented and non-pigmented apical cell membranes. Between the ciliary and retinal margins there are adherens and tight focal junctions which attach pigmented apical cell membranes to adjacent cells. There were no differences in the distribution of intercellular junctions between albino and pigmented rabbits.

Animals↗
PubMed1995

Plasmid coding for drug resistance and invasion of epithelial cells in enteropathogenic Escherichia coli 0111:H.

Enteropathogenic Escherichia coli (EPEC) can adhere to, invade and multiply in human epithelial cells. To define the elements required for bacterial invasion, we isolated from an 0111:H- EPEC a 6.6 kb plasmid that is capable of conferring to an avirulent, non-adherent E. coli K12 strain (DK1) the capacity to invade epithelial cells. With this system a dissociation was possible between bacterial invasion and adherence to epithelial cells. Bacteria containing this plasmid synthesise a protein of 32 kDa (pl 4.93) which seemed to be required for cell invasion. The results provide a new basis for strategies to prevent EPEC infections.

Animals↗
PubMed1990

Lysosomal depletion in macrophages from spleen and foot lesions of Leishmania-infected hamster.

Analysis of lysosomes through acid phosphatase cytochemistry at the electron microscopy level has been performed in spleen and foot lesions from Leishmania-infected hamsters. The results showed that there is lysosomal depletion in macrophages from Leishmania donovani chagasi-infected hamster spleen and similar findings were obtained from foot lesions of Leishmania mexicana amazonensis-infected hamsters. The distribution of acid phosphatase and thiamine pyrophosphatase was also examined in the Golgi apparatus. It was possible to demonstrate that the activity of ACP is absent in infected macrophages from spleen and foot lesions of Leishmania-infected hamster while the distribution of TPP was very similar in control and infected macrophages from both systems. These results provide evidence that the lysosomal depletion can occur at the ACP synthesis and/or glycosylation level.

Acid Phosphatase↗
PubMed1981

Ultrastructural differences between species of trypanosomatids with and without endosymbionts.

Species of trypanosomatids without endosymbionts (Leptomonas seymouri, L. collosoma, L. samueli, crithidia fasciculata, C. luciliae, C. acanthocephali, Herpetomonas megaseliae, H. mariadeanei, H. samuelpessoai, H. muscarum muscarum, Trypanosoma cruzi) and species of trypanosomatids with endosymbionts (Crithidia deanei, C. oncopelti, Blastocrithidia culicis) were comparatively studied by means of electron microscopy. Artificially aposymbiotic strains derived from species with symbiont were also included in the survey. Species with symbiont were found to differ in some ultrastructural aspects from the group of species without symbiont. Paraxial rods of flagella or intraflagellar structure were found exclusively in species without symbiont. Peripheral branching of mitochondria, accompanied by absence of subpellicular microtubules in sites where the mitochondrial branches are appressed to the cell membrane, were found exclusively in species with symbiont. Networks of kinetoplast DNA fibrils were found to be larger and looser in species with symbiont. Symbiont-free strains of species with symbiont retained the same morphological characteristics of their parental species.

Animals↗
PubMedDate not supplied

Development of trypanosomatids in the phytophagous insect Dysdercus peruvianus (Hemiptera: Pyrrochoridae). A light and eletron microscopic study.

Experimental infections of the phytophagous Hemiptera Dysdercus peruvianus with different trypanosomatids were studied for up to 55 days by light microscopy while the course of infection with Leptomonas seymouri and the Leptomonas isolate 49/553G.O. was analyzed by electron microscopy. Rates of infection of D. peruvianus varied according to the infecting flagellate. The lower part of the midgut was found to be the preferential site of colonization where most flagellates were found isolated or arranged in clumps or rosettes. Specialized junctional structures with host cells were never observed. Flagellates could also be seen inside midgut cells within a parasitophorous vacuole. Infection of haemocoele and salivary glands was also observed.

Animals↗
PubMedDate not supplied

Ultrastructural study of enteropathogenic Escherichia coli O111ab:H2 infection in an infant with acute diarrhea.

Enteropathogenic Escherichia coli is the most important cause of acute diarrhea in developing countries, specially in infants under one year of age. Enteropathogenic Escherichia coli strains are able to induce profound cytoskeletal alterations in the enterocyte known as attaching and effacing lesions, associated with the formation of cuplike pedestals. We report an Enteropathogenic Escherichia coli O11ab:H2 strain isolated from an infant with acute diarrhea, on the eleventh day of disease, that caused attaching and effacing lesion and penetrated the enterocyte, as well as invaded the HeLa cell tissue culture in vitro and the rabbit ileal loop assay in vivo, in the ultrastructural study. This observation indicates that the severe lesions of the small bowel caused by an enteropathogenic Escherichia coli O111ab:H2 strain can occur even in the early stages of the infection.

Acute Disease↗
PubMedDate not supplied

[Serotypes of classical enteropathogenic Escherichia coli that produce changes in the small bowel ultrastructure and invasion of HeLa cells].

UNLABELLED: Enteropathogenic Escherichia coli (EPEC) is the main cause of diarrhea in infants up to one year of age in the majority of the developing countries. In vitro EPEC strains attach to HeLa or HEp-2 cells in a specific pattern called localized adherence (LA), which is correlated with 93% of the EPEC serotypes. In vivo, EPEC strains adhere intimately to cuplike projections of the apical enterocyte membrane causing localized destruction of the microvilli, described as an attaching and effacing lesion. PURPOSE: We showed the attaching-effacing lesions and intracellular penetration in the ultrastructural study of the small intestinal cells as well as in the HeLa cell assay by the following EPEC serotypes: O111ab:H2, O119:H6 and O18ab:H14. PATIENTS AND METHODS: These strains were isolated from the stools of three infants less than 2 years of age with watery diarrhea who were hospitalized for fluid and electrolyte repairment. In the three patients there were severe ultrastructural alterations of the enterocytes mainly shortening and destruction of the microvilli, and formation of cuplike pedestal lesions. There was also penetration of microorganisms into the cytoplasm of the enterocytes in the interior of endocytotic vesicles. The serotypes of EPEC were assayed with HeLa cells showing the formation of pedestals and penetration into the cytoplasm. CONCLUSION: The ultrastructural alterations of the small bowel observed in these patients represent an important indication of the possibility of perpetuation of the diarrhea, owing to either a secretory mechanism or malabsorption of the nutrients.

Acute Disease↗