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Biomedical subjects

E H LEDUC

Publications and source records attributed to E H LEDUC.

At least 19 recordsLinked to original sources
PubMed1963

Mitochondrial changes in the liver of essential fatty acid-deficient mice.

Livers of mice on diets deficient in essential fatty acids (EFA) have been studied by light and electron microscopy. The most conspicuous changes occur in the mitochondria. In light microscopy the mitochondria appear very much enlarged in the periportal region of the lobule. In electron micrographs they have additional cristae, sometimes very abundant. ranged in stacks in the central cavity. The matrix may be more electron-opaque than normal. This is in contrast with the enlarged mitochondria appearing under other experimental conditions, where the cristae are reduced in number and the matrix is less electron-opaque. It is known that there is an uncoupling of oxidative phosphorylation in EFA-deficient mitochondria. As a hypothesis it is proposed that the uncoupling may be due to a molecular defect caused by the absence of EFA in the structure that determines the spatial relationship between the electron transport chain and oxidative phosphorylation. It is further tentatively suggested that the changes in mitochondria may be attributed to lack of ATP. The possibility is discussed that the mitochondrial changes are ineffective attempts at compensation for this lack.

Animals↗
PubMed1961

Ultrastructural cytochemistry. Enzyme and acid hydrolysis of nucleic acids and protein.

Selective extraction of specific cell components by enzyme or acid hydrolysis is possible from ultrathin sections for electron microscopy and parallel 2 micro sections for light microscopy of tissues fixed in formalin and embedded in a water-soluble polyepoxide, product X133/2097. Normal rat tissues fixed 15 minutes in formalin at 3 degrees C are more rapidly digested by proteinases than those fixed for the same length of time at 20 degrees C. Trypsin selectively attacks the nuclear chromatin and the ribonucleoprotein particles of the ergastroplasm, whereas mitochondria and zymogen granules resist tryptic digestion. Pepsin rapidly attacks the mitochondria and zymogen granules. The ergastoplasm and nucleus at first resist peptic digestion, but in time the entire cytoplasm and interchromatinic portion of the nucleus are attacked. Ribonuclease abolishes cytoplasmic basophilia in 2 micro sections, but parallel ultra-thin sections, stained with uranyl acetate and examined in the electron microscope, show no change in the ribonucleoprotein particles of the ergastoplasm. Desoxyribonuclease alone had no effect, but after pretreatment of the sections with pepsin or hydrochloric acid, desoxyribonuclease specifically attacked the nuclear chromatin. Nucleic acid-containing structures in the sections are gradually disintegrated by perchloric acid or hydrochloric acid.

Animals↗
PubMed1959

An electron microscope study of intranuclear inclusions in mouse liver and hepatoma.

An electron microscope study of intranuclear inclusions which occur in giant cells in a transplantable mouse hepatoma and in enlarged liver cells in mice fed a diet containing bentonite demonstrates that these inclusions are formed by invaginations of the nuclear envelope, and corroborates a previous histochemical study which revealed that the contents of the inclusions are of cytoplasmic origin. In the hepatoma cells the intranuclear inclusions are abundant, small, and situated close to the border of the nucleus, and there are wide openings from the cytoplasm into the invaginations whose contents include lipid droplets, ergastoplasm, and structurally normal mitochondria. In the enlarged liver cells the inclusions are fewer in number, generally much larger than those in the hepatoma, hence they extend deeper into the nucleus, and the interior is continuous with the cytoplasm through only a small opening. Some normal ergastoplasm is present within the inclusions but all other constituents are abnormal. Both normal and degenerating mitochondria occur in the cytoplasm but only degenerating ones are found within the inclusions. Both types of inclusions arise in greatly enlarged cells in which an attempt is made to maintain the normal nuclear surface/nuclear volume ratio by the development of the invaginations of the nuclear envelope.

Animals↗
PubMed1955

Studies on antibody production. I. A method for the histochemical demonstration of specific antibody and its application to a study of the hyperimmune rabbit.

A method for the specific histochemical demonstration of antibody in cells and parts of cells is described. It consists of carrying out a two stage immunological reaction on frozen sections of tissues: (a) allowing reaction between antibody in the tissue and dilute antigen applied in vitro, and (b) the detection of those areas where this antigen has been specifically absorbed by means of a precipitin reaction carried out with fluorescein-labelled antibody. Examination under the fluorescence microscope reveals the yellow-green fluorescence of fluorescein over those areas where a precipitate has formed. A study of the hyperimmune rabbit on the first few days after the last of a series of intravenous antigen injections reveals that antibody against human gamma-globulin or ovalbumin is present in groups of plasma cells in the red pulp of the spleen, the medullary areas of lymph nodes, the submucosa of the ileum, and the portal connective tissue of the liver. Because of extensive non-specific reactions, the bone marrow could not be examined. Small amounts of antibody were occasionally visible in cells in the lymphoid follicles of the spleen and lymph nodes, so that a minor contribution by lymphocytes to antibody synthesis cannot be excluded.

Animals↗
PubMed1955

Studies on antibody production. II. The primary and secondary responses in the popliteal lymph node of the rabbit.

After an antigenic stimulus, antibody is first demonstrable in the cytoplasm, and often in a spot in the nucleus, of large, immature cells in the medullary areas of the lymph node draining the site of injection. Morphologically, these cells have basophilic cytoplasm and a large nucleus, and are typical hematogenous stem cells. As these cells multiply and differentiate, the concentration of antibody in their cytoplasm increases, until colonies of typical mature plasma cells containing antibody have developed. There is a marked difference between the primary and the secondary responses, the former characterized by the development of very few antibody-containing cells while in the latter there are hundreds in a similar area. The morphology of the cells involved in both responses is identical. Occasionally, antibody was also found in low concentration in association with the lymphoid follicles. The implications of these findings for an understanding of antibody synthesis are discussed.

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