Biomedical subjects

K Takata

Publications and source records attributed to K Takata.

At least 109 records · Page 6Linked to original sources

PubMed1996

Developmental expression of proprotein-processing endoprotease furin in rat pancreatic islets.

The expression of furin in pancreatic beta-cells induces faster cell growth and a decrease in differentiated beta-cell-specific characteristics. During the development of rat pancreatic islets, the prohormone convertases, PC2 and PC3, appear during late gestation and are expressed long after birth. We investigated the developmental change in another yeast Kex2 family endoprotease, furin, in rat islets in relation to islet cell growth. Furin had appeared by gestational day 18 and was distributed in islets as well as exocrine tissues. The expression of furin in islets increased toward the neonatal stage. Bromodeoxyuridine (BrdU) incorporation was also elevated in the perinatal period. On postnatal days 10 and 20, staining characteristics were attenuated. On day 25, immediately after weaning, furin staining began to localize in the beta-cell region, and staining in the alpha-cell region became fainter. On day 270, the staining in the alpha-cell region disappeared, and staining in the beta-cell region remained positive, but was weaker. We conclude that furin expression was greatest during the perinatal period, when BrdU incorporation into islets was maximal. Furin expression continued, however, even after the BrdU incorporation decreased. Thus, furin appears to control the proliferation as well as differentiation of islet cells.

Aging↗

PubMed1996

[A course of pirarubicin vesical irrigation at thirty mg effectively prevents post-TUR recurrence of superficial bladder cancer].

In order to study its safety and anti-cancer dose-effectiveness in the prevention of cancer recurrence, two groups of patients having superficial bladder cancer (TUR-Bt) had their bladder intravesically irrigated post-surgically with 20 or 30 mg aliquots of (2''R)-4'-0-tetrahydropyranyl-adriamycin (THP). A total of 74 patients with bladder cancer were entered in the study. Four cases proved ineligible, and 30 could not complete the planned treatment. THP vesical irrigation of 14-17 sessions was regarded as a condition for eligibility: Clinical evaluation was feasible with 19 patients of 20 mg and 21 of 30 mg THP. Non-recurrence rates at 1, 2, 3 and 4 years were 89.5, 53.3, and 26.6%, respectively, for the 20 mg group, and 95.2, 84.3, 75.9 and 75.9%, respectively, for the 30 mg THP group. The incidence of side effects appeared slightly greater in the 30 mg THP group than in the 20 mg group, and there were no systemic adverse reactions. Topical reaction of cystitis was noted to be as low as 12.5%. Thus, THP vesical irrigations at 30 mg were found tolerable and effective for the prevention of local recurrence following TUR-Bt.

Administration, Intravesical↗

PubMed1995

Structural and functional analysis of the canine histamine H2 receptor by site-directed mutagenesis: N-glycosylation is not vital for its action.

G-protein-coupled receptors generally share a similar structure containing seven membrane-spanning domains and extracellular site(s) for N-glycosylation. The histamine H2 receptor is a member of the family of G-protein-coupled receptors, and has three extracellular potential sites for N-glycosylation (Asn-4, Asn-162 and Asn-168). To date, however, no information has been presented regarding N-glycosylation of the H2 receptor. To investigate the presence, location and functional roles of N-glycosylation of the H2 receptor, site-directed mutagenesis was performed to eliminate the potential site(s) for N-glycosylation singly and collectively. The wild-type and mutated H2 receptors were expressed stably in Chinese hamster ovary (CHO) cells or transiently in COS7 cells. Immunoblotting of the wild-type and mutated H2 receptors with an antiserum directed against the C-terminus of the H2 receptor showed that mutation at Asn-162, but not at Asn-168, resulted in a substantial decrease in the molecular mass. A mutation at Asn-4 led to a further decrease in the molecular mass. Tunicamycin treatment of the transfected cells yielded a sharp band with a molecular mass identical to that of the mutant devoid of all three potential sites for N-glycosylation. These findings indicate that the H2 receptor is N-glycosylated, and that N-glycosylation takes place mainly at two sites, Asn-4 and Asn-162. Neither the affinity for tiotidine nor that for histamine was affected by the mutagenesis. Immunocytochemistry and tiotidine binding showed that the mutated receptors were exclusively distributed on the cell surface in a fashion similar to that of the wild-type. In addition, the glycosylation-defective receptor was capable of activating adenylate cyclase and elevating the intracellular Ca2+ concentration in response to histamine in stable CHO cell lines. Thus N-glycosylation of the H2 receptor is not required for cell surface localization, ligand binding or functional coupling to G-protein(s).

1-Methyl-3-isobutylxanthine↗

PubMed1995

Effects of fluvastatin on human biliary lipids.

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have rapidly become widespread in the treatment of hypercholesterolemia and are known to be variable in efficacy. To investigate the effect on biliary lipids, a 3-month study using fluvastatin was devised. A total of 19 patients were enrolled in this study: all had hypercholesterolemia (7 men, 12 women; 13 with type IIa, 6 with type IIb). After an observation period of 4-6 weeks with placebo, fluvastatin at a daily dose of 30 mg was administered for 3 months. Fasting blood samples were taken early in the morning, before, and once a month during 3 months of fluvastatin treatment, for measurement of serum lipids. Cerulein-stimulated bile in the gallbladder was sampled using a duodenal tube, and the changes in biliary lipids were assessed. There was a marked decrease in serum total cholesterol after 12 weeks of treatment (21%; p < 0.001). However, there was no significant difference in the bile cholesterol saturation index (CSI): values before and after 3 months of drug administration were 0.93 and 0.99, respectively (Admirand-Small method). There were no significant changes in either the fatty acid composition of biliary lecithin or in the bile acid composition of bile. In conclusion, on the basis of these results, short-term (3 months) administration of fluvastatin does not appear to affect CSI.

Adult↗

PubMed1995

Pain drawing in the evaluation of low back pain.

Pain drawings were obtained from three groups of patients: 51 with lumbar disc herniation; 55 with lumbar stenosis, and 42 with benign low back pain. On grid assessment, patients with disc herniation and stenosis who complained of radiating pain or intermittent claudication had a significantly larger number of grids for the extremities than those with benign low back pain. In studies of the relation between the characteristics of the pain drawing and the outcome of treatment, most patients with 19 grids or less, or a score of 3 points or less, had a satisfactory outcome. Those with more grids or a higher score tended to be unsatisfactory. Pain drawing permits differentiation of the three patterns of pain and is useful for predicting the outcome of treatment.

Activities of Daily Living↗

PubMed1995

Peanut agglutinin binding to human prolactin-producing pituitary adenomas.

Peanut agglutinin (PNA)-binding sites in human prolactin (PRL)-producing pituitary adenomas were examined by light and electron microscopy together with immunoblot analysis. At the light microscopic level, the majority of the PRL-producing adenoma cells stained positively for PNA in 15 of 20 cases. PNA binding observed in the cytoplasm had a granular appearance. PRL-producing cells adjacent to the adenoma tissue showed negative PNA staining. In normal pituitary glands, the PRL-positive glandular cells were negative for PNA staining. By electron microscopy, reaction products showing PNA-binding sites were detected in some of the secretory granules. Immunoblotting analysis revealed that the PRL bands corresponded to PNA-stained ones with the exception of the main 23-kDa band. PNA-binding sites have some relation to the secretory granules containing glycosylated forms of PRL. These observations suggest that PNA staining can be used as a valuable method to analyze human PRL-producing pituitary adenomas.

Adenoma↗

PubMed1995

Origin of posterior pituitary high intensity on T1-weighted magnetic resonance imaging. Immunohistochemical, electron microscopic, and magnetic resonance studies of posterior pituitary lobe of dehydrated rabbits.

RATIONALE AND OBJECTIVES: To investigate the origin of posterior pituitary high intensity (PPHI) seen on T1-weighted magnetic resonance (MR) images. METHODS: Six rabbits, including four rabbits deprived of drinking water for 4 days and two control rabbits, were examined by MR imaging. Plasma vasopressin levels were sequentially measured by radioimmunoassay. Pituitary glands were immunostained with guinea pig anti-rabbit vasopressin antibody, and ultrathin sections of Epon/Araldite-embedded specimens were observed with a transmission electron microscope. RESULTS: In control rabbits, PPHI was noted on T1-weighted MR images, and the posterior pituitary lobe was positively immunostained with anti-vasopressin antibody. At the ultrastructural level, nerve terminals contained numerous neurosecretory granules bearing vasopressin. Conversely, plasma vasopressin levels gradually increased and PPHI was absent in 4-day dehydrated rabbits. The posterior lobe was scarcely stained with anti-vasopressin antibody, and neurosecretory granules were rarely observed. However, a number of small dispersed vesicles, possibly derived from the fragmentation of neurosecretory granule envelopes, were seen in the nerve terminal. CONCLUSIONS: Posterior pituitary high signal seen on T1-weighted MR images is attributed to neurosecretory granules bearing vasopressin.

Animals↗

PubMed1995

A new case of apoA-I deficiency showing codon 8 nonsense mutation of the apoA-I gene without evidence of coronary heart disease.

We report a 39-year-old Japanese man with HDL and apoA-I deficiency as well as data from members of his family. Corneal opacity and a stomatocyte were found but not tonsillar hypertrophy, xanthomas, or splenomegaly. His serum HDL cholesterol, apoA-I, apoA-II, and LDL cholesterol levels were t mg/dL, < 3 mg/dL, 6 mg/dL, and 175 mg/dL, respectively. Plasma triglyceride, phospholipid, apoB, apoC-III, and apoE levels were all within normal limits. Lecithin:cholesterol acyltransferase activity was half of normal, while lipoprotein lipase and hepatic triglyceride lipase activities were within normal limits. ApoA-I deficiency was confirmed by combined isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by an immunoblotting method. We surveyed the apoA-I gene of the patient and five of his family members by direct sequencing after amplification by polymerase chain reaction and found a codon 8 nonsense mutation (TGG --> TAG, Trp --> stop) in exon 3 of the apoA-I gene. The results of a pedigree analysis by DNA sequencing and restricted fragment length polymorphism (Sty I) were consistent with an autosomal codominant trait. Coronary angiography was performed to evaluate coronary atherosclerosis, but no significant luminal narrowing was detected. An intracoronary ultrasound study showed mild intimal hyperplasia in segment 6. In summary, this is a case of apoA-I deficiency without evidence of coronary heart disease.

Adolescent↗

PubMed1995

Different effects of subclasses of HDL containing apoA-I but not apoA-II (LpA-I) on cholesterol esterification in plasma and net cholesterol efflux from foam cells.

We investigated the effects of subclasses of plasma LpA-I (HDL containing apoA-I but not apoA-II) on cholesterol esterification in plasma and net cholesterol efflux from foam cells. LpA-I was composed of particles of three diameters: large (11.1 nm; Lg-LpA-I), medium (8.8 nm; Md-LpA-I), and small (7.7 nm; Sm-LpA-I). Plasma concentrations of LpA-I were positively correlated only with the level of Lg-LpA-I. Plasma concentrations of Lg-LpA-I were inversely correlated with the rate of cholesterol esterification in plasma and VLDL- and LDL-depleted plasma. Plasma concentrations of Md-LpA-I and Sm-LpA-I did not correlate with the rate of cholesterol esterification in plasma or VLDL- and LDL-depleted plasma. When macrophage foam cells were incubated with Md- and Sm-LpA-I, cellular cholesterol mass was reduced by approximately 70%. In contrast, the cellular cholesterol-reducing capacity of Lg-LpA-I was negligible. Lg-LpA-I inhibited net cholesterol removal from foam cells that was mediated by Md- and Sm-LpA-I and cholesteryl ester production with these particles. These results suggest that Md- and Sm-LpA-I may actively participate in cellular cholesterol removal and cholesterol esterification in plasma and HDL, while Lg-LpA-I may regulate these functions of Md- and Sm-LpA-I.

Adolescent↗

PubMed1995

Characterization of rat GLUT5 and functional analysis of chimeric proteins of GLUT1 glucose transporter and GLUT5 fructose transporter.

To investigate the biological and biochemical properties of GLUT5, rat GLUT5 complementary DNA was transfected into Chinese hamster ovary cells. Rat GLUT5 was exclusively targeted to the plasma membrane and exhibited a transport activity, not for glucose, but for fructose. The affinity for fructose (Km = 11.6mM) was much higher than that of GLUT2, the other glucose transporter with fructose transport activity. Interestingly, rat GLUT5 was not photolabeled with 0.5 microM cytochalasin B, whereas a similar amount of GLUT1 was adequately photolabeled under the same experimental conditions. Next, to investigate the domains required for transport of glucose/fructose in GLUT1 and/or GLUT5, several chimeric GLUT1/GLUT5 proteins were expressed, and their glucose and/or fructose transport activities were studied. The intracellular middle loop and the region encompassing the membrane spanning domains 7-12 were observed to have crucial roles in GLUT1 glucose transport, whereas replacement of the N-terminal half or the intracellular C-terminal region with the corresponding region of GLUT5 produced no marked effects on glucose transport activity. In contrast, both the N-terminal half encompassing the region from the N-terminus through the 6th membrane spanning domain and the intracellular C-terminal region were mandatory for GLUT5 fructose transport. In conclusion, GLUT5 is a transporter exclusively for fructose and the structural requirements for fructose transport are more stringent than those for glucose transport among hexose transporter proteins.

Affinity Labels↗

PubMed1995

The granin family--its role in sorting and secretory granule formation.

Two types of secretory pathways are present in mammalian cells: constitutive secretion and regulated secretion (1). In the constitutive secretory pathway, which is found in all types of cells, secretory products are packed in small vesicles. Most of the proteoglycans and glycoproteins of the extracellular matrix are secreted in this way. The regulated secretory pathway, found in the more differentiated secretory cells, is mediated by specialized secretory granules. Hormones and neuropeptides are secreted in this way. Both the constitutive and regulated secretory pathways emanate from the trans-Golgi network (TGN). Recent studies have indicated that the granin family (secretogranins/chromogranins) plays an important role in the sorting and aggregation of secretory products in the trans-Golgi network (TGN), and in the subsequent formation of secretory granules. The granin family is thought to be one of the mediators of the regulated secretory pathway (2-6). This family is widely expressed in endocrine (7-9) and neuronal cells (10-12), where they are stored in secretory granules together with various peptide hormones and neuropeptides. Three acidic sulfated proteins, chromogranin A (Cg A), secretogranin I (Sg I; also called chromogranin B; Cg B), and secretogranin II (Sg II) are well known as the major proteins in the family. Recently, three acidic secretory proteins, 1B1075 gene product (13), HISL-19 antigen (14) and 7B2 (15), have been thought to be members of the granin family, accordingly termed as Sg III, Sg IV and Sg V, respectively. However, it still remains open to discussion whether 1B1075 gene product, the HISL-19 antigen and 7B2 are true members of the granin family. In this review, the possible roles of granin family, especially Cg A, Sg I (Cg B) and Sg II in the regulated secretory pathway are discussed, focusing on the sorting, aggregation of proteins in the TGN, and subsequent secretory granule formation.

Animals↗

PubMed1995

Structural and functional differences of subspecies of apoA-I-containing lipoprotein in patients with plasma cholesteryl ester transfer protein deficiency.

ApoA-I-containing lipoproteins exist in plasma in two main forms: one contains only apoA-I (LpA-I) while the other contains both apoA-I and apoA-II (LpA-I/A-II). We characterized structural and functional changes of these lipoproteins in six patients with cholesteryl ester transfer protein (CETP) deficiency. In these patients, the amount of LpA-I and LpA-I/A-II had increased significantly. Sixty-five percent of plasma apoA-I was associated with LpA-I/A-II, which indicated that LpA-I/A-II was predominant. The chemical composition of both LpA-I and LpA-I/A-II was characterized by increased ratios of neutral to polar lipid, compared with findings in normal subjects. Particle sizes of these lipoproteins shifted to larger diameter ranges, as compared to the size seen in normal subjects. Incubation of patients' LpA-I and LpA-I/A-II with CETP markedly corrected the chemical and physical abnormalities in these lipoproteins. Cholesterol-reducing capacities of these lipoproteins from macrophage foam cells were significantly lower than in normal controls. Cholesterol esterification rates in LpA-I, LpA-I/A-II, and plasma were significantly lower in patients than in normal controls. We propose that the structure and function of LpA-I and LpA-I/A-II are severely affected in the presence of CETP deficiency.

Apolipoprotein A-I↗

PubMed1995

[A familial case of ADPKD with intracranial aneurysms detected by MR angiography].

The management and screening of unruptured asymptomatic intracranial aneurysm (ICA) in patients with ADPKD and those with a family history of ICA remains a subject of considerable controversy. In recent years, it has been revealed that MRA (magnetic resonance angiography) can define the circle of Willis to allow detection of ICA as small as 3-4 mm. We report a case of a 63-year-old man with ADPKD and his family. No definite aneurysm was observed by angiography screening at 46 years of age, when he was referred for hemodialysis. For the past three years, his family history revealed that three relatives were suffering from subarachnoid hemorrhage at the ages of 32, 36 and 39 years, respectively, two of whom had ICA and one had arterio-venous malformation detected by angiography. Whether they had ADPKD was unknown, but two were suggestive of ADPKD. Therefore, our case underwent MRA as screening for ICA, which showed an ICA with a diameter of 5mm in the anterior communicating artery. The ICA was confirmed as being 6 mm in diameter by conventional angiography. His niece and her son, who had ADPKD, also underwent MRA, which showed a suspicious image of a 2 mm ICA in the latter case. These results suggest that prophylactic screening for ICA is important in an ICA clustering family. MRA is useful in screening for ICA and in the follow-up study on the natural course of ICA.

Adult↗

PubMed1995

Immunohistochemical localization of Na(+)-dependent glucose transporter in the rat digestive tract.

Glucose is actively absorbed in the intestine by the action of the Na(+)-dependent glucose transporter. Using an antibody against the rabbit intestinal Na(+)-dependent glucose transporter (SGLT1), we examined the localization of SGLT1 immunohistochemically along the rat digestive tract (oesophagus, stomach, duodenum, jejunum, ileum, colon and rectum). SGLT1 was detected in the small intestine (duodenum, jejunum and ileum), but not in the oesophagus, stomach, colon or rectum. SGLT1 was localized at the brush border of the absorptive epithelium cells in the small intestine. Electron microscopical examination showed that SGLT1 was localized at the apical plasma membrane of the absorptive epithelial cells. SGLT1 was not detected at the basolateral plasma membrane. Along the crypt-villus axis, all the absorptive epithelial cells in the villus were positive for SGLT1, whose amount increased from the bottom of the villus to its tip. On the other hand, cells in the crypts exhibited little or no staining for SGLT1. Goblet cells scattered throughout the intestinal epithelium were negative for SGLT1. These observations show that SGLT1 is specific to the apical plasma membrane of differentiated absorptive epithelial cells in the small intestine, and suggest that active uptake of glucose occur mainly in the absorptive epithelial cells in the small intestine.

Animals↗

PubMed1995

Immunohistochemical localization of the glucose transporter GLUT1 in choroid plexus papillomas.

Normal chroid plexus tissue and five choroid plexus papillomas were examined with antibody specific for the glucose transporter GLUT1, one isoform of facilitated-diffusion glucose transporters, using the avidin-biotin-peroxidase complex (ABC) technique. GLUT1 in normal choroid plexus was localized at the basolateral plasma membrane of almost all epithelial cells. In three of five tumors, GLUT1 immunoreactivity was observed. A positive reaction was demonstrated at the plasma membrane of tumor cells. The number of GLUT1-positive cells was, however, much smaller than that of the normal choroid plexus. Our results suggest that GLUT1 expression in the choroid plexus is restrained during the course of transformation and that choroid plexus papilloma is composed of various differentiation tumor cells.

Adolescent↗

PubMed1995

Detection of a glycosphingolipid antigen in bladder cancer cells with monoclonal antibody MRG-1.

The monoclonal antibody MRG-1 has been evaluated for the immunohistochemical detection of the type 3 chain of blood group A in human normal bladder epithelium and bladder tumours. Light microscope examination of paraffin sections demonstrated that this antigen was present in normal epithelium and superficial bladder tumour in patients with blood group A or AB, but was absent in the invasive type of bladder tumour. In normal epithelium, the plasma membrane was positive for this antigen, and the cytoplasm was diffusely stained. In superficial transitional cell carcinoma, the plasma membrane was negative, whereas the cytoplasm was intensely stained in the perinuclear region. This pattern was different from that observed for type 1 and 2 group A antigen, which was recognized mainly at the plasma membrane. However, in superficial transitional cell carcinoma, the staining was also seen on the plasma membrane. The pattern of the localization of this antigen in this carcinoma was influenced by the treatment of organic solvents. Electron microscopical observations confirmed that this antigen was localized on the plasma membrane and also in the Golgi apparatus of the superficial tumour. These results proved that the type 3 chain of blood group A is present in human bladder epithelium and low grade tumours in correspondence with the blood type, but disappears in tumours with high malignant potential. However, its expression is independent of the expressions of the other subtypes which have been studied. Furthermore, the changes in the staining pattern caused by pretreatment with organic solvents suggested possible differences in the microenvironment of the glycolipids containing this type of sugar chain.

Animals↗

PubMed1995

Immunohistochemical localization of glucose transporters in human renal cell carcinoma.

The localization of 2 isoforms of glucose transporters (GLUT1 and GLUT4) in 75 patients with renal cell carcinoma was examined immunohistochemically. Paraffin sections were immunostained with either anti-GLUT1 or GLUT4 antibody by the avidin-biotin-peroxidase complex method. In 55 of 75 patients, GLUT1 staining was demonstrated at the plasma membrane of the cancer cells. In the clear cell subtype, 44 of 52 (84.6%) patients were positive for GLUT1. We did not detect positive staining for GLUT1 in the spindle cell type. In the mixed cell subtype, positive staining was recognized in only the areas of clear cell carcinomas (10 of 13; 76.9%). Positive staining for GLUT1 did not show any significant correlation with tumor grade or extent. Heterogeneous expression of GLUT1 was observed in tumor cell mass: some tumor cells were positive for GLUT1, while other cells were not. In adjacent normal tissue, GLUT1 staining was only recognized at the plasma membrane of some renal tubules. GLUT4 staining was not recognized in either tumor or normal tissues.

Carcinoma, Renal Cell↗

PubMed1994

Evidence for impaired cellular cholesterol removal mediated by apo A-I containing lipoproteins in patients with familial lecithin: cholesterol acyltransferase deficiency.

We investigated the cholesterol reducing capacity of two species of lipoproteins containing apo A-I, one containing only apo A-I (LpA-I) and the other containing apo A-I and apo A-II (LpA-I/A-II), in 7 patients (4 homozygotes and 3 heterozygotes) with familial lecithin: cholesterol acyltransferase (LCAT) deficiency. Interaction of normal LpA-I or LpA-I/A-II with macrophage foam cells induced a mass reduction in cholesterol from these cells and the cholesterol reducing capacity of LpA-I was greater than that of LpA-I/A-II. When foam cells were incubated with these lipoproteins from homozygotes or heterozygotes, the capacity of LpA-I and LpA-I/A-II particles to reduce cellular cholesterol was decreased by approx. 50% in the homozygotes but was increased by 25-50% in the heterozygotes. These results suggest that LpA-I and LpA-I/A-II isolated from homozygotes and from heterozygotes differ in their ability to accept cellular cholesterol. The former are poor and the latter good acceptors of intracellular cholesterol. We conclude that factors other than reverse cholesterol transport via apo A-I containing lipoproteins have to be considered to explain why homozygotes for LCAT deficiency are not at high risk for premature atherosclerosis.

Adult↗