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H Shio

Publications and source records attributed to H Shio.

At least 55 records · Page 3Linked to original sources
PubMed1988

Peroxisomal integral membrane proteins in control and Zellweger fibroblasts.

An entire organelle, the peroxisome, appears to be missing in Zellweger syndrome, causing profound neurological problems and neonatal death. One hypothesis for the molecular cause of this defect is a failure in the assembly of the peroxisomal membrane. An alternative is that the peroxisomal membrane is assembled, but the post-translational import of the matrix proteins is defective. We have investigated these possibilities by analytical cell fractionation, immunoblotting, and immunoelectron microscopy of fibroblasts. We identified four integral membrane proteins that can serve as markers for the human peroxisomal membrane. In Zellweger fibroblasts, peroxisomal membranes were found but they were abnormal; they had an equilibrium density of 1.10 g/cm3 instead of the normal density of 1.17 g/cm3, their diameters were generally 2-4 times greater than normal, and they lacked most content. The existence of these peroxisomal ghosts in Zellweger syndrome fibroblasts supports the hypothesis that the defect in this disease is in the protein import machinery.

Cell Line↗
PubMed1988

Peroxisomal membrane ghosts in Zellweger syndrome--aberrant organelle assembly.

Peroxisomes are apparently missing in Zellweger syndrome; nevertheless, some of the integral membrane proteins of the organelle are present. Their distribution was studied by immunofluorescence microscopy. In control fibroblasts, peroxisomes appeared as small dots. In Zellweger fibroblasts, the peroxisomal membrane proteins were located in unusual empty membrane structures of larger size. These results suggest that the primary defect in this disease may be in the mechanism for import of matrix proteins.

Fibroblasts↗
PubMed1988

Antithrombotic treatment in livedo vasculitis.

Two patients with livedo vasculitis were treated successfully with antiplatelet drugs including ticlopidine hydrochloride, dipyridamole, and low-dose aspirin. Increased platelet functions were restored 1 week after the beginning of the treatment, followed by dramatic improvement of painful leg ulcers within 1 month. Livedo status was unchanged. We claim that antiplatelet therapy should be the first choice of treatment in this disease.

Adult↗
PubMed1988

Secretion of Plasmodium falciparum rhoptry protein into the plasma membrane of host erythrocytes.

The rhoptry is an organelle of the malarial merozoite which has been suggested to play a role in parasite invasion of its host cell, the erythrocyte. A monoclonal antibody selected for reactivity with this organelle identifies a parasite synthesized protein of 110 kD. From biosynthetic labeling experiments it was demonstrated that the protein is synthesized midway through the erythrocytic cycle (the trophozoite stage) but immunofluorescence indicates the protein is not localized in the organelle until the final stage (segmenter stage) of intraerythrocytic development. Immunoelectron microscopy shows that the protein is localized in the matrix of the rhoptry organelle and on membranous whorls secreted from the merozoite. mAb recognition of the protein is dithiothreitol (DTT) labile, indicating that the conformation of the epitope is dependent on a disulfide linkage. During erythrocyte reinvasion by the extracellular merozoite, immunofluorescence shows the rhoptry protein discharging from the merozoite and spreading around the surface of the erythrocyte. The protein is located in the plasma membrane of the newly invaded erythrocyte. These studies suggest that the 110-kD rhoptry protein is inserted into the membrane of the host erythrocyte during merozoite invasion.

Animals↗
PubMed1988

Zellweger syndrome amniocytes: morphological appearance and a simple sedimentation method for prenatal diagnosis.

Zellweger syndrome is the prototype of a growing group of genetic diseases caused by an absence or deficiency of peroxisomes. The defect causes the enzyme catalase to remain in the cytosol instead of being packaged into peroxisomes. This mislocalization can be easily detected by sedimentation analysis. Amniocytes were homogenized and then centrifuged to pellet organelles. Catalase was found to sediment with the peroxisomes in the homogenates of normal cells, but to remain in the supernatant with Zellweger syndrome amniocyte homogenates. This striking difference is unambiguous and reproducible, and provides a simple method for prenatal diagnosis. Moreover, it allows one to differentiate diseases in which peroxisomes are deficient from other peroxisomal diseases in which the organelle is intact, but one enzyme is defective. Electron microscopic observations support the biochemical determinations. Normal amniocytes contain small peroxisomes in which a weak cytochemical reaction for catalase may be demonstrated. Zellweger amniocytes appear to lack these organelles, although some cells have rare structures that might be residual or abnormal peroxisomes.

3,3'-Diaminobenzidine↗
PubMed1987

Primary structure and subcellular localization of the knob-associated histidine-rich protein of Plasmodium falciparum.

Plasmodium falciparum-infected erythrocytes bind to venular endothelial cells by means of electron-dense deformations (knobs) on the parasitized erythrocyte surface. The primary structure of a parasite-derived histidine-rich protein associated with the knob structure was deduced from cDNA sequence analysis. The 634 amino acid sequence is rich in lysine and histidine and contains three distinct, tandemly repeated domains. Indirect immunofluorescence, using affinity-purified monospecific antibodies directed against recombinant protein synthesized in Escherichia coli, localized the knob-associated histidine-rich protein to the membrane of knobby infected erythrocytes. Immunoelectron microscopy established that the protein is clustered on the cytoplasmic side of the erythrocyte membrane and is associated with the electron-dense knobs. A role for this histidine-rich protein in knob structure and cytoadherence is suggested based upon these data.

Amino Acid Sequence↗
PubMed1987

Efficient association of in vitro translation products with purified stable Candida tropicalis peroxisomes.

Newly synthesized peroxisomal proteins enter preexisting peroxisomes posttranslationally in vivo, generally without proteolytic processing. An efficient reconstitution of this process in vitro together with cloned DNAs for peroxisomal proteins would make possible investigation of the molecular information that targets proteins to peroxisomes. We have previously reported the isolation of clones for Candida tropicalis peroxisomal proteins; here we describe the association (and possible import) of peroxisomal proteins with peroxisomes in vitro. C. tropicalis was grown in a medium containing Brij 35, resulting in the induction of a moderate number of medium-sized peroxisomes. These peroxisomes, isolated in a sucrose gradient, had a catalase latency of 54% and were sufficiently stable to be concentrated and used in an import assay. The reticulocyte lysate translation products of total RNA from oleate-grown cells were incubated with the peroxisomes at 26 degrees C in the presence of 50 mM KCl, protease inhibitors, 0.5 M sucrose, 2.5 mM MOPS (morpholinepropanesulfonic acid) (pH 7.2), and 0.5 mM EDTA. Ten major translation products (which could be immunoprecipitated with antiserum against peroxisomal protein) became progressively associated with the peroxisomes during the first 30 min of incubation (some up to approximately 70%). These include acyl coenzyme A oxidase and the trifunctional protein hydratase-dehydrogenase-epimerase. This association did not occur at 4 degrees C nor did it occur if the peroxisomes were replaced with mitochondria.

Acyl-CoA Oxidase↗
PubMed1985

Effects of common carotid artery damage on anti-platelet-aggregability and PGI2 production in rats.

The effects of vascular damage on platelet function were investigated in rats. Common carotid artery specimens 4 mm in length were dissected from male Wistar rats and exposed to ultrasonic treatment or rubbing of the intimal surface. In some cases, carotis was dissected after ligation for 4 hr. The specimens were fixed on a stirring bar and agitated in platelet-rich plasma added with ADP. After determining platelet aggregability, the plasma was subjected to radioimmunoassay for 6-keto-prostaglandin F1 alpha (6-K-PGF1 alpha). Anti-platelet-aggregability in the arterial specimens was significantly greater in the sonicated, rubbed or ligated specimens than in the intact group, probably due to the effect of prostacyclin (PGI2). The measurement of 6-K-PGF1 alpha levels yielded similar results. Endogenous arachidonic acid in the vessel wall seems to be utilized in the production of PGI2, which probably acts only on local platelets. The findings indicate the presence of a mechanism that inhibits the formation of platelet thrombi by the accelerated production of PGI2 under conditions favorable for the generation of thrombosis.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Partial disassembly of peroxisomes.

Rat liver peroxisomes were subjected to a variety of procedures intended to partially disassemble or damage them; the effects were analyzed by recentrifugation into sucrose gradients, enzyme analyses, electron microscopy, and SDS PAGE. Freezing and thawing or mild sonication released some matrix proteins and produced apparently intact peroxisomal "ghosts" with crystalloid cores and some fuzzy fibrillar content. Vigorous sonication broke open the peroxisomes but the membranes remained associated with cores and fibrillar and amorphous matrix material. The density of both ghosts and more severely damaged peroxisomes was approximately 1.23. Pyrophosphate (pH 9) treatment solubilized the fibrillar content, yielding ghosts that were empty except for cores. Some matrix proteins such as catalase and thiolase readily leak from peroxisomes. Other proteins were identified that remain in mechanically damaged peroxisomes but are neither core nor membrane proteins because they can be released by pyrophosphate treatment. These constitute a class of poorly soluble matrix proteins that appear to correspond to the fibrillar material observed morphologically. All of the peroxisomal beta-oxidation enzymes are located in the matrix, but they vary greatly in how easily they leak out. Palmitoyl coenzyme A synthetase is in the membrane, based on its co-distribution with the 22-kilodalton integral membrane polypeptide.

Animals↗
PubMed1985

Zellweger syndrome: biochemical and morphological studies on two patients treated with clofibrate.

Two infants with Zellweger syndrome (cerebro-hepato-renal syndrome) have been studied biochemically and morphologically. Peroxisomal enzymes involved in respiration, fatty acid beta-oxidation, and plasmalogen biosynthesis were assessed. In liver, catalase was present in normal amounts but was located in the cell cytosol. Dihydroxyacetone phosphate acyltransferase activity was less than one-tenth of normal. The amount of the bifunctional protein catalyzing two beta-oxidation reactions was found by immunoblotting to be greatly reduced. Catalase activity was normal in intestine. D-Amino acid oxidase was subnormal in kidney. The observed enzyme deficiencies may plausibly explain many of the metabolite imbalances observed clinically. Morphologically, peroxisomes were absent from liver. In intestine, normal peroxisomes were also missing, but some rare, smaller (0.04-0.13 micrometer) bodies were seen with a slight positive cytochemical reaction for catalase. These results, together with current concepts of peroxisome biogenesis, suggest but do not prove, that the primary defect in Zellweger syndrome may be in peroxisome assembly. The infants were treated with clofibrate, but it was ineffectual as assessed biochemically, morphologically, and clinically.

Abnormalities, Multiple↗
PubMed1984

Lipoprotein-heparin-fibronectin-denatured collagen complexes enhance cholesteryl ester accumulation in macrophages.

The sequestration of low-density lipoprotein (LDL) by components of the vascular extracellular matrix has long been recognized as a contributing factor to lipid accumulation during atherogenesis. The effects, however, that components of the extracellular matrix might have on LDL catabolism by scavenger cells have been little investigated. For these purposes we have prepared insoluble complexes of LDL, heparin, fibronectin, and denatured collagen (gelatin) and examined their effects on lipid accumulation, LDL uptake and degradation, and cholesteryl ester synthesis in mouse peritoneal macrophages. The results of these experiments have demonstrated that the cholesteryl ester content of macrophages incubated with a particular suspension of LDL, heparin, fibronectin, and collagen complexes is four- to fivefold that of cells incubated with LDL alone. The uptake of complexes containing 125I-LDL is rapid; however, in contrast to either endocytosed 125I-LDL or 125I-acetyl LDL, the degradation of complex-derived LDL is impaired. In addition, the uptake of complex-derived LDL stimulates the incorporation of [14C]oleic acid into cholesteryl oleate, however, the stimulation was a small fraction of that observed in cells incubated with acetyl LDL. Ultrastructurally, macrophages incubated with LDL, heparin, fibronectin, and collagen complexes did not contain many lipid droplets, but rather their cytoplasm is filled with phagosomes containing material similar in appearance to LDL-matrix complexes. These results indicate that components of the extracellular matrix can alter the catabolism of LDL by scavenger cells, suggesting that they may play a role in cellular lipid accumulation in the atherosclerotic lesion.

Animals↗
PubMed1984

Scanning electron microscopy studies of erythrocytes in spinocerebellar degeneration.

Spinocerebellar degeneration is a heredofamilial disease of unknown aetiology. The shape of erythrocytes as revealed by scanning electron microscopy was studied in this disease. Echinocytes I, as defined by Bessis, were seen more frequently in spinocerebellar degeneration than in age and sex matched controls (7.2 +/- 1.5% in spinocerebellar degeneration, 3.4 +/- 1.2% in controls, p less than 0.001), Parkinson's disease, motor neuron disease, myopathy, and Huntington's chorea. Erythrocyte deformability was impaired to a greater extent in spinocerebellar degeneration than in the controls when the pH was raised from 7.2 to 8.0; Echinocytes I in spinocerebellar degeneration increased from 8.4 +/- 0.6 to 15.4 +/- 2.4%, in the control group from 2.8 +/- 1.2 to 13.3 +/- 2.1%. In spinocerebellar degeneration no significant correlation was found between the level of serum low density lipoprotein and the number of Echinocytes I. In both groups there was a significant correlation between the occurrence of Echinocytes I and age, and the difference of Echinocytes I was greater in aged subjects in spinocerebellar degeneration. The data suggest that membrane abnormality in erythrocytes exists in spinocerebellar degeneration and may be accelerated with the advance of age.

Adult↗