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K Takata

Publications and source records attributed to K Takata.

At least 217 records · Page 12Linked to original sources
PubMed1986

Scavenger receptor for malondialdehyde-modified high density lipoprotein on rat sinusoidal liver cells.

We report here the presence of a membrane-associated receptor which mediates endocytic uptake of malondialdehyde-modified high density lipoprotein (MDA-HDL) on sinusoidal liver cells. Binding of [125I]MDA-HDL to the cells was followed by internalization and degradation in lysosomes. The binding and lysosomal degradation of [125I]MDA-HDL were effectively inhibited by unlabeled MDA-HDL and acetyl-HDL. However, formaldehyde-treated serum albumin or low density lipoprotein modified either by acetylation or malondialdehyde, ligands known to undergo receptor-mediated endocytosis by sinusoidal liver cells, did not affect the binding of [125I]MDA-HDL to the cells. These results indicate that a receptor for MDA-HDL is described as a distinct member among the scavenger receptors for chemically modified proteins.

Acetylation↗
PubMed1986

Scavenger receptor for aldehyde-modified proteins.

This paper describes an unexpectedly broad ligand specificity of a scavenger receptor of sinusoidal liver cells that is responsible for endocytic uptake of formaldehyde-treated bovine serum albumin (f-Alb). Binding of 125I-f-Alb to the isolated cells was effectively inhibited by bovine serum albumin (BSA) modified with aliphatic aldehydes such as glycolaldehye, DL-glyceraldehyde, and propionaldehyde whereas albumin preparations modified by aromatic aldehydes such as pyridoxal, pyridoxal phosphate, salicylaldehyde, and benzaldehyde did not affect this binding process. Binding of 125I-glycolaldehyde-treated BSA to the cells exhibited a saturation kinetics with an apparent Kd = 3.3 micrograms of the ligand/ml. This binding process was inhibited by unlabeled f-Alb as well as by the antibody raised against the f-Alb receptor. Indeed, 125I-glycolaldehyde-treated BSA underwent a rapid plasma clearance (t1/2 approximately 2 min) which was markedly retarded by unlabeled f-Alb. Upon treatment by these aldehydes, other proteins such as ovalbumin, soybean trypsin inhibitor, and hemoglobin were also converted to active ligands for the f-Alb receptor, while no ligand activity was generated with gamma-globulin and RNase A. These results clearly show that the f-Alb receptor, originally described as being specific for f-Alb, exhibits a broad ligand specificity in terms of both aldehydes and proteins and, hence, should be described as a scavenger receptor for aldehyde-modified proteins.

Acetaldehyde↗
PubMed1986

Recycling of the glucose transporter, the insulin receptor, and insulin in rat adipocytes. Effect of acidtropic agents.

The notion of an insulin-dependent translocation of the glucose transporter in rat adipocytes was confirmed by immunoblotting and reconstitution of glucose transport activity of subcellular fractions. Quantitatively, however, significantly different results were obtained with these two techniques; when compared with reconstitution, immunoblotting detected translocation of a larger amount of the transporter from a low density microsome fraction to a plasma membrane fraction. The acidtropic agents chloroquine and dibucaine, which have been reported to inhibit the recycling of various receptors, were utilized to study the detailed translocation mechanism of the glucose transporter and the insulin receptor. These acidtropic agents caused accumulation of 125I-insulin in a subcellular fraction probably corresponding to lysosomes. They did not, however, significantly affect either the insulin-induced activation of glucose transport or the recycling of the transporter and the insulin receptor as detected by immunoblotting. About 50% of radioactivity released from adipocytes which were allowed to internalize insulin was due to intact insulin, and chloroquine did not change the release rate of intact insulin, raising the possibility of receptor-mediated exocytosis of insulin. The release of degraded insulin decreased with chloroquine treatment. The results are consistent with the idea that these acidtropic agents mainly act to inhibit degradation of insulin in lysosomes, and their effect on the recycling of the glucose transporter and the insulin receptor is minimal, indicating that the recycling of these membrane proteins proceeds irrespective of organelle acidification. Electron micrographs showed vesicles underneath the plasma membranes, with sizes similar to those of the low density microsome fraction where the internalized glucose transporter and the insulin receptor were located.

3-O-Methylglucose↗
PubMed1986

Bullous pemphigoid--a scanning electron microscopic study.

Skin blisters at different stages were taken from 4 patients with bullous pemphigoid and studied mainly by scanning electron microscopy. The under-surface of the roof of the newly formed blisters was composed of columnar or cuboidal epidermal cells. Their intercellular space was dilated. Most of the cells were degenerated and shed off into the blister fluid. The under-surface of the roof of the fully developed blisters was composed of flattened epidermal cells which were polygonal in shape. These findings suggest that the basal cells are degenerated and shed off into the blister fluid, so that the prickle cells become flattened and directly face the blister fluid during blister formation.

Aged↗
PubMed1986

[A case of bilateral reticulum cell sarcoma of the testis].

A case of reticulum cell sarcoma of bilateral testis is described. The patient was a 58-year-old man who complained of painless swelling of the right scrotal contents. He was treated by bilateral high orchiectomy. The right testicular tumor was histologically diagnosed as reticulum cell sarcoma, and the left testicular tumor was also diagnosed as RCS. Chemotherapy (vincristin, Endoxan, 6-MP and prednisolone) was performed, and the patient has been doing well without any clinical evidence of recurrence. The literature is reviewed briefly.

Combined Modality Therapy↗
PubMed1986

[A case of bilateral testicular tumor of germ cell origin].

A 28-year-old man visited our clinic with a complaint of painless swelling of left scrotal contents. An initial right semicastration for embryonal carcinoma and seminoma had been performed 10 years earlier. Left semicastration was performed, and its histopathological finding was pure seminoma. A total of 96 cases of bilateral testicular tumors of germ cell origin reported in Japan are summarized and discussed concerning incidence, age, histology, interval, prognosis and mechanism of the tumorigenesis.

Adult↗
PubMed1985

Characterization of a membrane-associated receptor from rat sinusoidal liver cells that binds formaldehyde-treated serum albumin.

When treated with formaldehyde, serum albumin is known to be taken up and degraded by sinusoidal liver cells via adsorptive endocytosis. The present study aimed at characterization and identification of the membrane-associated receptor on rat sinusoidal liver cells. Kinetic studies of binding of 125I-labeled formaldehyde-treated serum albumin (125I-f-Alb) with the membranes of sinusoidal liver cells demonstrated the presence of specific, high-affinity, saturable membrane-bound receptors with an apparent Kd = 8 micrograms of f-Alb/ml and the optimal pH at around 8.0. The 125I-f-Alb binding to the membranes was not inhibited by either native albumin, asialofetuin, methylamine-treated alpha 2-macroglobulin, mannan, or immune complexes. The binding process exhibited independence of calcium and susceptibility both to heat treatment and to destruction by proteases. The binding was inhibited by concanavalin A and the inhibition was effectively reversed by the presence of alpha-methyl-D-glucoside, a haptenic inhibitor for this lectin, indicating the glycoprotein nature of the receptor. The binding protein was extracted from the membrane preparations with octyl beta-D-glucopyranoside and immunoprecipitated by anti-ligand antibody as a complex with the ligand. Sodium dodecyl sulfate-gel electrophoresis of the immunoprecipitate revealed two polypeptide chains with molecular weights of approximately 53,000 and 30,000, respectively.

Animals↗
PubMed1985

Purification of a receptor for formaldehyde-treated serum albumin from rat liver.

A membrane-associated receptor involved in a specific uptake of formaldehyde-treated serum albumin (f-Alb) was purified from rat livers by Triton X-100 solubilization of a 105,000 X g membrane preparation and affinity chromatography on an f-Alb-Sepharose column. The purified receptor exhibited Mr = 125,000, consisting of two noncovalently linked glycoprotein components with Mr = 53,000 and Mr = 30,000, respectively. Incubation of 125I-receptor with f-Alb, but not with native albumin, resulted in a marked shift of pI value from 5.9 to 5.1, reflecting the presence of a specific ligand-receptor interaction. The receptor incorporated into liposomes displayed a saturable binding to 125I-f-Alb and the binding was effectively replaced by the presence of unlabeled f-Alb, with binding parameters being similar to those obtained from 125I-f-Alb binding to the sinusoidal liver cell membrane (Horiuchi, S., Takata, K., and Morino, Y. (1985) J. Biol. Chem. 260, 475-481). Reaction of anti-f-Alb receptor antibody with extracts of sinusoidal cells resulted in a specific precipitation of two proteins whose molecular weights were identical to those for the purified receptor. The anti-receptor IgG fraction effectively blocked 125I-f-Alb binding to the sinusoidal cell membranes. These results indicate that the purified protein represents the membrane-associated receptor which is presumably involved in a specific uptake of this ligand from the circulation.

Animals↗
PubMed1985

Scavenger function of sinusoidal liver cells. Acetylated low-density lipoprotein is endocytosed via a route distinct from formaldehyde-treated serum albumin.

Chemically modified proteins such as acetylated low-density lipoprotein (acetyl-LDL) and formaldehyde-treated serum albumin (f-Alb) infused intravenously are known to undergo receptor-mediated endocytosis by sinusoidal liver cells, major intravascular scavenger cells in vivo. The aim of the present study was to elucidate whether the endocytic uptake of acetyl-LDL and f-Alb is mediated by the same receptor or not. Experiments on the binding of 125I-acetyl-LDL to isolated rat liver sinusoidal cells revealed the presence of a specific, high-affinity, saturable, membrane-associated receptor with an apparent Kd = 7 micrograms of the ligand at 0 degrees C. Unlabeled acetyl-LDL effectively inhibited 125I-f-Alb binding to the cells. By contrast, the binding of 125I-acetyl-LDL to the cells was affected neither by unlabeled f-Alb nor by the antibody raised against the f-Alb receptor. These results indicate that the scavenger receptors for these two ligands are distinct from each other but similarly sensitive to polyanionic compounds.

Animals↗
PubMed1985

Lectin-binding pattern in extramammary Paget's disease by horseradish peroxidase (HRP)-labeling method--specific staining with Dolichos biflorus agglutinin (DBA).

Lectin-binding pattern in extramammary Paget's disease was studied using seven different lectins (Con A, WGA, RCA-I, PNA, SBA, DBA, and UEA-I) by means of the horseradish peroxidase (HRP)-labeling method. By light microscopy it was observed that Con A, WGA, RCA-I, and DBA stained almost all the extramammary Paget cells, while PNA, SBA, and UEA-I stained only some of them. Normal keratinocytes and tumor cells from other diseases such as mammary Paget's disease, malignant melanoma, squamous cell carcinoma, basal cell epithelioma, Bowen's disease, and seborrheic keratosis were positively stained with Con A, WGA, and RCA-I, but not with DBA except in some of the mammary Paget's cells. By electron microscopy it was observed that DBA stained the cell membrane and the Golgi apparatus of the extramammary Paget cells. The present results suggest that DBA is a specific lectin for glycoconjugates in extramammary Paget cells.

Carbohydrate Metabolism↗
PubMed1985

Lectin-binding pattern in normal human gastric mucosa. A light and electron microscopic study.

Normal human gastric mucosal cells were examined by light and electron microscopy using lectins as a probe. The ABC method was used with biotinylated lectins for light microscopy and HRP-labeled lectins for electron microscopy. The human gastric mucosal cells revealed specific binding patterns for each lectin by light microscopy. Among the lectins tested, in particular, DBA gave a characteristic pattern. It specifically stained the supranuclear region of surface epithelial cells and the perinuclear region of parietal cells. By electron microscopy, the stacked cisternae and the vesicles of the Golgi apparatus of the surface epithelial cells were positive for the DBA staining. These results show that the DBA-positive supranuclear region observed by light microscopy corresponds to the Golgi apparatus. In the parietal cells, DBA, RCA and ConA bound to the intracellular secretory canaliculi which are invaginations of the cell membrane running around the nucleus in the cytoplasm. Therefore, the tubular perinuclear positive region observed by light microscopy corresponds to the membranes of the intracellular secretory canaliculi. In addition, the ConA reagent stained the endoplasmic reticulum, Golgi apparatus, nuclear envelope, and cell membrane of the parietal cell, which explains the diffuse cytoplasmic staining observed at the light microscopic level with this lectin. Lectins have proved to be very useful for the evaluation of in situ cytochemical aspects of the glycoconjugates characteristic to human gastric mucosal cells.

Gastric Mucosa↗