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Biomedical subjects

E Y Chi

Publications and source records attributed to E Y Chi.

103 records · Page 6Linked to original sources
PubMed1978

Mast cell granule formation in the beige mouse.

The formation of mast cell granules was studied in the beige mouse utilizing histochemistry and electron microscopy. The time and sequence of appearance of heparin, histamine and the chymotrypsin-like protease were normal. By electron microscopy, the initial formation of progranules and subsequent aggregation was normal, but the granules from early stages were abnormally large. Reorganization of intermediate granule forms to homogeneous mature granules was delayed. Late fusions of intermediate and/or mature granules were not observed. Our findings indicate that the defect lies in the excessive initial fusion of progranules rather than in continued formation of new progranules or in fusion of mature granules with one another.

Animals↗
PubMed1978

Pulmonary surface-active materials in the Chediak-Higashi syndrome.

Beige mice express the Chediak-Higashi syndrome. Large inclusions, identified as abnormal lysosomes, are found in many cells. The inclusions in type II alveolar epithelial cells are enlarged lamellar bodies and they are associated with an increase in total lung surface-active material and phospholipid. Comparison of recovery of phospholipid in surface-active materials from beige and black (normal) mice indicates that in the beige mice there is an increase in total phospholipid and disaturated phosphatidylcholines in whole lung and in surface-active materials in residual lung after lavage. Hosphatidycholine and phosphatidylglycerol are increased as percentages of total lung phospholipid. Calculated alveolar surface coverage of surface-active materials isolated from residual beige lungs is greater than three times that of normal lungs. Surface-active materials recovered from beige mice are qualitatively similar in phospholipid composition and in surface activity to materials recovered from normal mice. The quantity of surface-active material phospholipid recovered in the lavage of beige mouse lungs was normal. The basis for the abnormal accumulation of lamellar body lipids is not known.

Animals↗
PubMed1977

Carbon tetrachloride-induced changes in mixed function oxidases and microsomal cytochromes in the rat lung.

The effects of a single exposure, by gastric intubation or inhalation, to carbon tetrachloride (CCL4) on rat lungs were assessed. By 1 to 7 days, focal areas of alveolar collapse, septal edema, and modification of type II pneumonocytes were observed. By 24 hours after exposure to the toxin, there were no identifiable changes in surfactant levels or distribution. Microsomes obtained from the lungs and prepared for analysis revealed marked decreases in cytochrome P-450 content and P-450-related N-demethylation of dimethylaniline. Only a transient reduction of cytochrome b5 occurred, with a rebound exceeding control values during the period of pulmonary healing. Whether the lung acted as an excretory route (following intubation) or as an absorption path (after inhalation) made little difference. Carbon tetrachloride had no effect on in vitro microsome composition and function unless supplemented with a reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) generating system. Under these circumstances, there was a reduction in both cytochromes b5 and P-450. Our data indicate that a considerable chemical modification of the pulmonary tissues had taken place, with no accompanying easily recognized changes in cellular structure. Furthermore, evidence for the in vitro destruction of pulmonary microsomal cytochromes P-450 and b5, unrelated to peroxidation, is indicated by these findings.

Administration, Oral↗
PubMed1976

Freeze-fracture study of mast cell secretion.

Within seconds after exposure of rat peritoneal mast cells to polymyxin B, bulges appear on the surface of the cells. Freeze-fracture electron microscopy reveals that each bulge overlies a mast cell granule. In contrast to the even distribution of intramembranous particles in the plasma membrane of unstimulated cells, the intramembranous particles in the stimulated cells are unevenly distributed in the membrane of the bulges with large patches of membrane lacking intramembranous particles. The membranes over the most prominent bulges are entirely free of intramembranous particles, and in some instances there is an increased concentration of intramembranous particles at the margins of the bulges. Perigranule membranes exhibit the same changes in distribution of intramembranous particles. Electron microscopy of thin sections of rapidly fixed, stimulated mast cells shows a peculiar structure of the membrane overlying some bulges; instead of the pentalaminar membranes previously demonstrated, the membrane at these sites of presumptive fusion of perigranule and plasma membrane assumes the form of a single dense lamina with a fine fuzzy coating on either side. It seems possible that membrane fusion and subsequent pore formation proceed in the stimulated mast cell through a stage of flight of intramembranous particles and molecular rearrangement of the other membrane components.

Animals↗
PubMed1976

Effect of colchicine on rat mast cells.

In the mast cell, a well-developed array of microtubules is centered around the centrioles. Complete loss of microtubules is observed when mast cells are treated with 10(-5) M colchicine for 4 h at 37 degrees C. The loss of ultrastructurally evident microtubules is associated with a marked change in the shape of mast cells from spheroids to highly irregular, frequently elongated forms with eccentric nuclei. In colchicine-treated cells the association of nucleus, Golgi apparatus, and centrioles is also lost. Mast cells exposed to 10(-5) M colchicine for 4 h at 37 degrees C retain 80% of their capacity to release histamine when stimulated by polymyxin B. Exocytosis is evident in stimulated cells pretreated with colchicine and lacking identifiable microtubules. When the conditions of exposure of mast cells to colchicine are varied with respect to the concentration of colchicine, the length of exposure, and the temperature of exposure, dissociation between deformation of cell shape and inhibition of histamine secretion is observed. These observations indicate that microtubules are not essential for mast cell histamine release and bring into question the assumption that the inhibitory effect of colchicine on mast cell secretion depends on interference with microtubule integrity.

Animals↗
PubMed1976

Abnormally large lamellar bodies in type II pneumocytes in Chediak-Higashi syndrome in beige mice.

Lamellar bodies in type II pneumocytes are markedly enlarged in beige mice. The irregular shapes of some of these enlarged specialized lysosomes suggest fusion of smaller ellipsoidal bodies to form the giant organelles, consistent with the proposal of others for the mechanism of formation of abnormal lysosomes in Chediak-Higashi syndrome. Examination of the structure of lamellar bodies by the freeze-fracture technique reveals highly ordered stacking or concentric wrapping of the constituent lamellae. The corrugated patterns evident on the surfaces of normal lamellae are also present in Chediak-Higashi syndrome lamellae. Both normal and Chediak-Higashi syndrome lamellae appear free of typical intramembranous particles. The corrugations seen in the lamellae closely resemble those seen on freeze-fracture of dispersions of lecithin in water.

Animals↗
PubMed1976

A rapid method for processing liver biopsy specimens for 2 micron sectioning.

We will describe a procedure for the preparation of thin sections (2 micron thick) of percutaneous liver biopsy specimens for routine histological analysis. The process results in better preservation of both cellular and structural detail. The thinner sections provide clearer definition of inflammatory infiltrates, cellular changes, and intracellular deposits. Re-examination of the pathological features of the liver with the use of this technique will provide stronger correlation of the structural and functional aspects of hepatic disease processes.

Biopsy, Needle↗
PubMed1975

Two polypeptide chain constituents of the major protein of the cornified layer of newborn rat epidermis.

The insoluble component of stratum corneum of rat epidermis yields two major bands after extraction with 8 M urea-mercaptoethanol-dithiothreitol. The ratio of these two bands is about 1:1 in terms of protein stain intensity and S-[14C]carboxymethyl label. Both polypeptides were purified to homogeneity by DE-52-cellulose, sodium dodecyl sulfate hydroxylapatite C column chromatography, and preparative DodSO4-polyacrylamide gel electrophoresis. The heavier polypeptide contains 30% alpha helix and the lighter contains 27% alpha helix as determined by circular dichroism studies. Both are sensitive to Pronase and resistant to trypsin, collagenase, and elastase. The lighter chain is stable to pepsin but the heavier can be partially degraded to a smaller polypeptide with a molecular weight similar to that of light chain. Amino acid analysis shows that the light chain contains 12 more tyrosine residues than does the heavy chain, suggesting that the light chain is not generated from the heavy chain. However, the two chains may have a common peptide region. Antiserum prepared against the heavier polypeptide can be completely absorbed by purified lighter polypeptide and vice versa indicating that both chains have some common antigenic determinants. Antibody against either chain can cross-react with the stratum corneum and keratohyalin granules in the epidermis of newborn rat as indicated by fluorescent microscopic observation. Similarly, this antibody also cross-reacts with the cell surface or the contents of spinous and granular cells, and very weakly with basal cells, indicating that the two proteins may be present in the lower strata as well as the stratum corneum.

Amino Acid Sequence↗
PubMed1975

Abnormal mast cell granules in the beige (Chédiak-Higashi syndrome) mouse.

Mast cells of beige (C57BL/6J) (bg-j/bg-j) mice were examined histochemically and ultrastructurally. Mast cell granules in the beige mice were markedly enlarged and irregular in shape. Granule contents stained uniformly with acidified toluidine blue, but with ruthenium red and Alcian Blue-safranin, two components were evident. The rims of the abnormal granules stained with ruthenium red and with Alcian Blue; the centers of the granules were clear with ruthenium red and stained with safranin. Mast cell granules thus represent another abnormal organelle in the Chédiak-Higashi syndrome.

Animals↗