Search PubMed⌕ Search

Biomedical subjects

K Furuno

Publications and source records attributed to K Furuno.

At least 145 records · Page 8Linked to original sources
PubMed1983

Ultrastructural studies on autolysosomes in rat hepatocytes after leupeptin treatment.

We have studied the morphological alterations of the lysosomal compartment in rat hepatocytes following intraperitoneal administration of leupeptin, using electron microscopy and cytochemical techniques. At 30 min after the injection, autophagic vacuoles (autophagosomes and autolysosomes), containing cytoplasmic organelles, increased in number in the vicinity of bile canaliculi and also near the Golgi apparatus. At 1 h, most of the autophagic vacuoles were autolysosomes, single membrane-limited bodies positive for acid phosphatase activity. Development of the autolysosomes was accompanied by the reciprocal disappearance of pre-existing secondary lysosomes. From 1 to 8 h, the autolysosomes varied to a great extent in both size and shape as a result of coalescence. Segregated organelles within the autolysosomes were gradually degraded into electron-lucent unidentifiable debris. At later, residual bodies were abundant in the cytoplasm, and occasionally, their contents were discharged into the space of Disse. From 9 to 12 h, the autolysosomes decreased in the volume and number and secondary lysosomes of normal shape and size appeared. The autolysosomes seem to persist for long periods because of a retarded degradation of sequestered materials in leupeptin-treated hepatocytes.

Acid Phosphatase↗
PubMed1983

Receptor-mediated introduction of pepstatin-asialofetuin conjugate into lysosomes of rat hepatocytes.

Pepstatin was linked through a carboxyl group to asialofetuin (PS-ASF). An analysis by separation of hepatocytes from nonparenchymal cells showed that PS-ASF was taken up by hepatocytes, following intravenous injection into rats. After the injection of PS-ASF, pepstatin concentration in the liver reached a maximum at 2 h and then decreased. In an analysis by differential centrifugation of the liver homogenate from rats injected with PS-ASF, pepstatin showed a lysosomal type subcellular distribution pattern. Isolation studies of tritosomes clearly demonstrated the exclusive accumulation of pepstatin within the lysosomes of livers from rats given PS-ASF (at 2 h after administration). Pepstatin contained in tritosomes was in a free form, as determined by column chromatography of Sephadex G-15. The activity of cathepsin D in the livers was markedly inhibited in rats given PS-ASF. However, the treatment of rats with PS-ASF had no effect on the hepatic lysosomal degradation of endocytosed FITC-labeled asialofetuin (FITC-ASF). Introduction of PS-ASF into the hepatocytes was followed by the immediate and time-dependent excretion of free pepstatin into the bile. Quantification of pepstatin excreted into the bile revealed that the biliary excretion route can account for the disappearance of pepstatin from the liver.

Animals↗
PubMed1983

Isolation of chloroquine-resistant Chinese hamster V79 cell variants that are also resistant to ammonium chloride.

Chloroquine-resistant (CQr) clones (CQ-21 and CQ-22) have been isolated from mutagenized hamster lung V79 cells by exposing the cells to a high dose of chloroquine. CQ-21 and CQ-22 showed about 3-fold higher resistance to chloroquine than the parental V79 cells, and they showed specific cross-resistance to another amine, NH4Cl, which is also concentrated in lysosomes. CQr clone showed no cross-resistance to other unrelated agents. Chloroquine-induced inhibition of [125I]ricin internalization was observed in both cell lines at neutral pH, but the inhibition of uptake was less in the variant. Also, the degradation of endogenous protein was slowed in the mutant; further, treatment of cells with 30 micrograms/ml of chloroquine inhibited the degradation of endogenous proteins in the parental V79, but not in CQ-22 cells. Similar levels of acid phosphatase, beta-glucuronidase and cathepsin D were observed in V79 and CQ-22 cells, but the level of cathepsin B was lower in the mutant. Electron microscopy showed an increased number of electron-dense bodies, possibly autophagosomes/lysosomes, in the mutant cells grown for 4 days with 5 micrograms/ml of chloroquine. Similar aberrant structures were observed in the parental V79 cells treated for only 3 h with 5 micrograms/ml of chloroquine.

Ammonium Chloride↗
PubMed1982

Appearance of autolysosomes in rat liver after leupeptin treatment.

The administration to rats of leupeptin produced prominent numbers of enlarged and irregularly shaped autolysosomes in hepatocytes. Percoll density equilibration of crude lysosomal fractions from rat livers showed that most lysosomal enzyme migrated form normal lysosomal density fractions toward higher density fractions within 30 min after leupeptin injection. The denser particles were ultrastructurally identified with the autolysosomes. In analysis by differential centrifugation of the liver homogenates, lysosomal enzymes became sedimentable with particles of greater sedimentation rate within 30 min after leupeptin injection. These changes in physical properties of lysosomes reverted to normal after 24 h, and concomitant disappearance of autolysosomes in hepatocytes was observed by electron microscopy. When the time course of distribution of leupeptin in subcellular fractions was analyzed, particle-bound leupeptin shifted with time to larger particle fractions in parallel with the shift of lysosomal enzyme distribution. Upon injection with leupeptin, cathepsin B activity was inhibited by more than 80% for about 3 h and was gradually restored to a normal level after 24 h. Leupeptin treatment caused marked delay of the degradation of endocytosed FITC-labeled asialofetuin in hepatic lysosomes, and its inhibitory effect lasted for over 9 h after the injection. It was suggested that autophagy is probably a normal process of protein degradation in hepatocytes, and because of a retarded digestion of sequestered materials, autolysosomes persisted for a long period and made up the majority of the lysosome population in the leupeptin-treated cells.

Acid Phosphatase↗
PubMed1982

Isolation and characterization of autolysosomes which appeared in rat liver after leupeptin treatment.

Autolysosomes were isolated from rat livers treated with leupeptin by a combination of differential and Percoll density gradient centrifugation techniques. The purified autolysosome fraction was verified by morphological analysis to be highly purified and to contain contaminants which were scarcely detectable. The enrichment of the lysosomal enzyme activities in the purified autolysosomes over the homogenate was 12-, 14-, 22-, and 24-fold for beta-glucuronidase, acid phosphatase, beta-N-acetylglucosaminidase, and cathepsin D, respectively. Measurement of the activity of the marker enzymes for various subcellular organelles also proved that the purified autolysosome fraction was essentially free from contamination by other organelles. When the autolysosomes isolated from rat livers treated with leupeptin for 1 h were disrupted by osmolysis, acid hydrolases were easily solubilized. Acid phosphatase, however, became membrane bound in the autolysosomes prepared at longer periods of time after the leupeptin treatment. The autolysosomes exhibited enhanced permeability of the membranes after a short duration of time after the leupeptin treatment (30 and 60 min) and became stabilized later. These changes in the properties of the autolysosomes with time after the leupeptin treatment may be interpreted as meaning that progressive rearrangement of the lysosomal constituents occurred within the autolysosomes with time after the genesis.

Animals↗
PubMed1976

Effect of D-Glucarates on basic antibiotic-induced renal damage in rats.

Dehydrated rats regularly develop acute renal failure following single injection of aminoglycoside antibiotics combined with dextran or of antibiotics only. Oral administration of 2,5-di-O-acetyl-D-glucaro-1,4-6,3-dilactone protected rats against renal failure induced by kanamycin-dextran. The protective effect was prevalent among D-glucarates, and also to other saccharic acid, hexauronic acids and hexaaldonic acids, although to a lesser degree, but not to a hexaaldose, sugar alcohols, substances inthe TCA cycle and other acidic compounds. D-Glucarates were effective against renal damage induced by peptide antibiotics as well as various aminoglycoside antibitocis. Dose-responses were observed in the protective effect of D-Glucarates. With a D-glucarate of a fixed size of dose, approximately the same degree of protection was obtained against renal damages induced by different basic antibiotics despite large disparities in administration doses of different antibiotics. D-Glucarates had the ability to prevent renal damage but not to cure it. Rats excreted acidic urine when they were spared from renal lesions by monosaccharides. The reduction effect of D-glucarates against nephrotoxicity of basic antibiotics was discussed.

Acute Kidney Injury↗
PubMed1976

Preventive effect of D-glucarate against renal damage induced by kanamycin.

Kanamycin-induced renal impairment in dehydrated rats was spared by the administration of sodium D-glucaro-1,4-lactone. In the plasma elimination and urinary excretion studies, D-glucarate-treated rats showed quick removal of the antibiotic from the body as compared with non-treated rats. Organ distribution study clearly demonstrated the potent nephrotoxicity of kanamycin and the reduction effect of D-glucarate against the nephrotoxicity. The drug level in the kidney in non-treated rats was more than two orders of magnitude higher than those in other organs such as the liver, lung and spleen, and remained high for 48 hours after antibiotic administration. In D-glucarate-treated rats the kidney content of the drug was diminished as compared with non-treated rats just after the antibiotic administration, followed by a gradual decline with time.

Animals↗
PubMed1975

Induction of fatty liver by ethanol drinking in KK and KK-Ay mice.

Marked fatty liver was found to develop in both KK and KK-Ay (yellow KK) mice when they were allowed free access to a 15% ethanol solution as drinking fluid. The present studies were undertaken to elucidate the characterization of the fatty liver and associated changes. Chemical analysis showed that accumulated lipids were mainly triglycerides, whose fatty acid composition was changed with increases in palmitoleic and oleic acids, indicating augmentation in endogenous lipogenesis. An accumulation of small fat droplets was histologically observed in centrolobular hepatocytes extending to perilobular zones. Among the tested mice of seven strains, only KK and KK-Ay mice developed the ethanol-induced fatty liver, and the latter mice were more susceptible. Growth, food and alcohol intakes, plasma levels of glucose, triglycerides, and immunoreactive insulin were also surveyed during the development of the alcoholic fatty liver. In contrast to high energy diet, ethanol induced neither development of obesity nor exaggeration of diabetic states. A possible correlation between the pathogenesis of the fatty liver and the genetic factor inherited in KK mice is discussed.

Age Factors↗
PubMed1975

Effects of nutritional factors on the development of ethanol-induced fatty liver in KK and KK-Ay mice.

KK and KK-Ay mice developed a steady and reproducible fatty liver when they were given free access to an ethanol solution as a drinking fluid for 10 to 20 days. The present studies were undertaken to elucidate effects of nutritional factors on liver fat contents of the mice given water or ethanol solution. In contrast to cornstarch, sucrose tended to increase the liver fat of control mice. A higher concentration of dietary casein lowered the liver fat of control mice, whereas the dietary concentration of cottonseed oil did not significantly affect the liver rat levels either in control or ethanol groups. Thus the standard basal diets favorable for the development of the alcoholic fatty liver have been established, for example, 10% cottonseed oil, 25 and 30% casein, 58.4 and 53.4% cornstarch for KK (12-15 weeds old) and KK-Ay (5-10 weeks old), respectively. Neither choline, myoinositol, nor any lipotropic agent tested prevented the development of the alcoholic fatty liver. Unlike in rats, orotic acid did not induce a fatty liver but rather alleviated the ethanol-induced fatty liver in these mice.

Age Factors↗
PubMed1975

Metabolic studies on the development of ethanol-induced fatty liver in KK-Ay mice.

Mechanisms involved in the development of the alcoholic fatty liver in KK-Ay mice were investigated. Incorporation studies using [14C]acetate and [3H]palmitate indicated that the half-life of hepatic triglycerides was doubled in the ethanol-ingesting mice, and utilization of the exogenous fat was significantly increases as compared with that of the control. No persistent alteration was recognized in hepatic oxidation of palmitate, as estimated by in vitro experiments using liver slices obtained from control and ethanol-drinking mice. Enzymic studies indicated that the activities of acetyl COA carboxylase, ATP citrate lyase, malic enzyme, and 6-phosphogluconate dehydrogenase were increased with ethanol drinking. The increment in hepatic triglycerides accumulated during ethanol ingestion was largely accounted for by palmitoleic, oleic, and linoleic acids. These findings demonstrated an augmentation in hepatic lipogenesis as well as an increased utilization of exogenous fats. Ethanol drinking did not cause any appreciable change in plasma triglyceride level and metabolism of adipose tissue. In summary of the present studies, accelerated lipogenesis and increased utilization of the dietary fats may be possible causal factors in the alcoholic fatty liver of KK-Ay mice.

ATP Citrate (pro-S)-Lyase↗
PubMed1974

Effect of D-glucaric acid derivatives on stability of rat liver lysosomes and erythrocytes.

For studies on the lysosome-stabilizing effect of D-glucaric acid derivatives which have been found to have anti-inflammatory effect, the available and soluble enzyme activities of acid phosphatase of rat liver lysosomes were determined. Saliployed as standards. Lysosomes were incubated with drugs under specific conditions which allowed the data on the stabilizing activity of the drugs to be reproducible. The inhibitory effect of D-glucaro-1, 4-lactone, salicylic acid and phenylbutazone onover a wide range of concentrations. D-glucaro-1, 4-lactone as well as salicylic acid exhibited concentration-dependent lysosome-stabilizing effect whereas phenlybutazone had an optimum concentration for its lysosome-stabilizing effect. In addition, D-glucaro-1, 4-lactone,saliclicacid and phenylubtazone were also examined for their effects on heat-induced and saponin-induced hemolysis of rat erythrocyres. Both salicylic acid and phenylbutazone exhibited potent stabilziing and labilizing effects on heat-induced and saponin-induced hemolysis of eryhthrocytes, respectively. D-glucaro-1, 4-lactone, however, was incabale of affecting the hemolysis of erythrocytes. There appears to be a difference in the mechanism of the lysosome-stabilizing effects between D-glucaric acid derivatives and other anti-inflammatory drugs.

Acid Phosphatase↗