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Biomedical subjects

Y Seino

Publications and source records attributed to Y Seino.

At least 73 records · Page 4Linked to original sources
PubMed2000

The insulinotropic mechanism of the novel hypoglycaemic agent JTT-608: direct enhancement of Ca(2+) efficacy and increase of Ca(2+) influx by phosphodiesterase inhibition.

We examined the effects of the novel hypoglycaemic agent JTT-608 [trans-4-(4-methylcyclohexyl)-4-oxobutyric acid] on insulin secretion using rat pancreatic islets, and analysed the mechanism of its effect. JTT-608 augmented 8.3 mM glucose-induced insulin secretion dose-dependently, and there was a stimulatory effect of 100 microM JTT-608 at both moderate and high concentrations (8.3, 11. 1 and 16.7 mM) of glucose, but not at low concentrations (3.3 and 5. 5 mM). In perifusion experiments, both phases of insulin release were enhanced, and the effect was eliminated 10 min after withdrawal of the agent. In the presence of 200 microM diazoxide and a depolarizing concentration (30 mM) of K(+), there was an augmentation of insulin secretion by 100 microM JTT-608, not only under high levels of glucose but also under low levels, and the effects were abolished by 10 microM nitrendipine. JTT-608 augmented insulin secretion from electrically permeabilized islets in the presence of stimulatory concentrations (0.3 and 1.0 microM) of Ca(2+), and the intracellular Ca(2+) concentration ([Ca(2+)](i)) response under 16.7 mM glucose, 200 microM diazoxide, and 30 mM K(+) was also increased. The cyclic AMP content in the islets was increased by 100 microM JTT-608, and an additive effect to 1 microM forskolin was observed, but not to 50 microM 3-isobutyl-1-methylxanthine (IBMX). JTT-608 inhibited phosphodiesterase (PDE) activity dose-dependently. We conclude that JTT-608 augments insulin secretion by enhancing Ca(2+) efficacy and by increasing Ca(2+) influx. This appears to be a result of the increased intracellular cyclic AMP concentration due to PDE inhibition.

Animals↗
PubMed2000

Effect of argatroban on trinitrobenzene sulfonic acid-induced colitis.

BACKGROUND: Recent studies have suggested that heparin is effective for treatment of inflammatory bowel disease (IBD) and its various effects (in addition to the anticoagulant effect). We evaluated the effects of argatroban as an antithrombin drug on trinitrobenzene sulfonic acid (TNB)-induced colitis, an established model of IBD. METHODS: Rats were randomly assigned to four groups in which mini-osmotic pumps containing saline (TNB-S), argatroban (TNB-A), or 100 U/kg heparin (TNB-H) were intraperitoneally implanted. Three days after the pumps were implanted, TNB was infused via the anus, and colitis was induced. After 5 days, prothrombin time (PT), activated partial prothrombin time (APTT), antithrombin III (AT-III), platelet, fibrinogen, colonic wet weight, macroscopic damage score, histological score, mucosal myeloperoxidase activity and mucosal leukotrien B4 (LTB4) levels were compared among the four groups. RESULTS: The APTT was prolonged in the heparin treatment group but only slightly prolonged in the argatroban treatment group. The platelet count and the fibrinogen level were higher in the TNB-S group than in the healthy control group and the AT-III level was slightly lower in the TNB-S group than in the healthy control group and lower still in the TNB-H group. CONCLUSIONS: The colonic wet weight was similar among the four groups while the macroscopic damage score, histological score, mucosal myeloperoxidase activity and the mucosal LTB4 level were significantly decreased in the TNB-A and TNB-H groups. Argatroban, as well as heparin may be effective for treatment of TNB-induced colitis.

Analysis of Variance↗
PubMed2000

Novel mutation in the nephrin gene of a Japanese patient with congenital nephrotic syndrome of the Finnish type.

BACKGROUND: Congenital nephrotic syndrome (CNS) of the Finnish type is a rare autosomal-recessive disorder. Kestila et al reported that a positionally cloned gene for a novel glomerular protein nephrin is mutated in CNS. Most Finnish patients have one of two mutations. In this study, we described a Japanese CNS family associated with a novel missense point mutation in the nephrin gene. METHODS: Reverse transcription-polymerase chain reaction, polymerase chain reaction, and sequence analysis were used. RESULTS: The patient had the three missense mutations homozygously. One mutation was already reported as sequence variant. The two other novel mutations were the GAG to AAG transition, leading to a Glu447Lys and the GAC to GTC transition, predicting an Asp819Val substitution in the nephrin protein. CONCLUSION: Our findings indicate that an abnormality of nephrin may cause CNS of the Finnish type in Japanese subjects.

Asian People↗
PubMed2000

T-1095, a renal Na+-glucose transporter inhibitor, improves hyperglycemia in streptozotocin-induced diabetic rats.

The effect of T-1095, an inhibitor of renal glucose reabsorption, on hyperglycemia and the expression of Na+-glucose cotransporters (SGLTs) and facilitative glucose transporter 2 (GLUT2) in streptozotocin (STZ)-induced diabetic rats was examined. There was an elevation of blood glucose, hemoglobin A1c (HbA1c), kidney weight, and urinary excretion of both glucose and albumin in STZ rats. Administration of 0.03% and 0.1% (wt/wt diet) T-1095 to STZ rats for 4 weeks improved the hyperglycemia and dose-dependently decreased HbA1c. Moreover, treatment with 0.1% (wt/wt diet) T-1095 in STZ rats for 8 weeks not only reduced blood glucose and HbA1c, levels but also prevented the elevation of urinary albumin levels and kidney weight and the development of epithelial vacuolation. The expression of renal SGLT2, a major glucose transporter in the kidney, was not different in normal, STZ, and T-1095-treated STZ rats. In contrast, the elevated renal GLUT2 level in STZ rats was suppressed by T-1095. These data suggest that T-1095 improves hyperglycemia by suppressing the renal reabsorption of glucose, which results in a suppression of the development of functional and histological changes and abnormal expression of GLUT2 in the kidney.

Albuminuria↗
PubMed2000

Gastric mucosal damage caused by monochloramine in the rat and protective effect of taurine: endoscopic observation through gastric fistula.

BACKGROUND AND STUDY AIMS: The mechanism of Helicobacter pylori-induced gastric mucosal injury is unknown, but H. pylori infection is conducive to accumulation in the stomach of monochloramine, a cytotoxic substance. The present study involved morphological investigation of the damaging effects of monochloramine on rat gastric mucosa, using endoscopic observations through a gastric fistula. The study also examined the protective effect of taurine against monochloramine-induced gastric mucosal lesions in rats. MATERIALS AND METHODS: The effects of monochloramine in rats were studied by administering the substance via a gastrostomy, which was then used to conduct a series of endoscopic observations. Local blood flow was measured using a laser Doppler method. Histological examination was carried out after 24 hours. Various monochloramine concentrations were used, and some animals were pretreated with taurine, a monochloramine scavenger, via the gastrostomy. RESULTS: Endoscopically, monochloramine was found to produce hemorrhagic mucosal erosions, mainly in the gastric body, in a time-dependent and concentration-dependent manner. Blood flow was decreased in advance of mucosal erosion. Taurine prevented mucosal injury by 30 mM monochloramine, the highest concentration tested. CONCLUSIONS: Although only the first 24 hours of mucosal injury were observed in the present study, the most likely mechanisms by which monochloramine caused injury to the gastric mucosa appeared to be both oxidative damage and a reduction in blood flow, impairing the mucosal defense mechanism.

Analysis of Variance↗
PubMed2000

Serum 4-hydroxy-2-nonenal-modified albumin is elevated in patients with type 2 diabetes mellitus.

4-Hydroxy-2-nonenal (HNE) is one of the major lipid peroxidation products with cytotoxic and mutagenic activity. It further reacts with protein residues such as histidine to generate stable Michael adducts. To evaluate the status of oxidative stress in the serum of type 2 diabetes mellitus, we constructed a sandwich enzyme-linked immunosorbent assay to measure serum HNE-modified albumin by the use of a specific monoclonal antibody (HNEJ-2) against HNE-histidine adducts as well as an antibody against human serum albumin. Serum of type 2 diabetes outpatients revealed significantly higher levels of HNE-modified albumin (736.1 +/- 34.2 pmol/ml, n = 54) than the matched nondiabetics (611.4 +/- 39.1 pmol/ml, n = 30; means +/- SEM; p = 0.018). However, no significant correlation was observed in diabetic outpatients between the levels of HNE-modified albumin and clinical parameters such as fasted blood glucose, HbA1c, diabetes duration, or complications. Our data demonstrated the increased formation of serum HNE-modified albumin in type 2 diabetic outpatients in the milieu between liver and vascular lumina, indicating the presence of oxidative stress.

Aged↗
PubMed2000

Blockade of cardiac ATP-sensitive K+ channel by cibenzoline targets its pore-forming subunit.

Several antiarrhythmic agents with Na-channel blocking action have been shown to inhibit cardiac K(ATP) channels. We used cibenzoline to examine its precise target site using patch-clamp techniques and receptor binding assays in guinea-pig ventricular myocytes. Exposure of myocytes to a glucose-free perfusate containing 1 mM cyanide produced a time-dependent shortening of the action potential duration (APD) in the current-clamp mode. Cibenzoline (30 microM) slowed the development of APD shortening (APD90 to approximately 91% vs. approximately 55% control 16 min after metabolic inhibition) at pHo 7.4, but not at pHo 6.4 (to approximately 60%). The pinacidil (30 microM)-induced K(ATP) currents were inhibited by cibenzoline in a pHo-dependent manner: the higher the pHo, the stronger the blocking effect of cibenzoline. The binding of [3H]-labeled cibenzoline was prevented by cibenzoline, but not by glibenclamide. Alkalinization produces a higher concentration of the uncharged form of cibenzoline, which can more easily permeate the cell membrane than the charged form. In NIH3T3 cells stably expressing Kir6.1, a putative pore-forming subunit of K(ATP) channel, cibenzoline but not glibenclamide inhibited the K conductance. Thus cibenzoline interacts with the channel pore-forming subunit of the K(ATP) channel (Kir6.2), but not the sulfonylurea receptor, from the cytosolic side after it permeates into the cell interior via the membrane lipid bilayer.

Action Potentials↗
PubMed2000

Therapeutic effect of basic fibroblast growth factor on experimental pancreatitis in rat.

Basic fibroblast growth factor (bFGF) is one of the mitogens that facilitate endothelial proliferation and angiogenesis. This study was designed to examine the therapeutic effect of bFGF on experimental pancreatitis in rat. Edematous pancreatitis was induced by intraperitoneal injections of cerulein (50 microg/kg) at hourly intervals. BFGF (70 nmol/kg) was administered intraperitoneally after induction of pancreatitis. DNA synthesis of isolated pancreatic acinar cells of normal rats was determined as the uptake of 5-bromo-2'-deoxyuridine (BrdU) into the cells. Immunohistochemical staining of DNA synthesis in acinar cells during cerulein-induced pancreatitis was also examined with BrdU labeling in vivo technique. Cerulein administration increased serum amylase, lipase level, and wet weight of pancreatic tissue. Treatment with bFGF markedly ameliorated all these parameters. In primary culture system of isolated pancreatic acinar cells of normal rats, bFGF caused a dose-dependent increase in BrdU incorporation into DNA, showing an EC50 value of 0.8 nmol/L and a maximum response of 2.5-fold increase at a concentration of 400 nmol/L. bFGF treatment (70 nmol/kg) markedly increased BrdU labeling in the nucleus of acinar cells of the pancreatitis rats group in immunohistochemical examination when compared with control without bFGF treatment. Treatment with bFGF may represent a promising therapeutic concept for patients with acute pancreatitis.

Animals↗
PubMed2000

Suppressive effects of human herpesvirus-6 on thrombopoietin-inducible megakaryocytic colony formation in vitro.

Two clinical observations, the association of human herpesvirus-6 (HHV-6) with delayed engraftment after stem cell transplantation and thrombocytopenia concomitant with exanthema subitum, prompted us to evaluate the suppressive effects of HHV-6 on thrombopoiesis in vitro. Different culture conditions for thrombopoietin (TPO)-inducible colonies in semi-solid matrices were examined. Using cord blood mononuclear cells as the source of haematopoietic progenitors, two types of colonies, megakaryocyte colony-forming units (CFU-Meg) and non-CFU-Meg colonies, were established. The former colonies were identified by the presence of cells with translucent cytoplasm and highly refractile cell membrane, most of which were positive for the CD41 antigen. Although the plating efficiency of both types was much higher under serum-containing conditions than under serum-free conditions, the proportion of CFU-Meg to non-CFU-Meg colonies was consistently higher under serum-free conditions. The plating efficiency of CFU-Meg colonies was doubled by adding stem cell factor to the serum-free matrix. The effects of two variants of HHV-6 (HHV-6A and 6B) and human herpesvirus-7 (HHV-7) on TPO-inducible colonies were then compared. HHV-6B inhibited both CFU-Meg and non-CFU-Meg colony formation under serum-free and serum-containing conditions. HHV-6A had similar inhibitory effects. In contrast, HHV-7 had no effect on TPO-inducible colony formation. Heat-inactivation and ultra-filtration of the virus sample completely abolished the suppressive effect. After infection of CD34(+) cells with HHV-6, the viral genome was consistently detected by in situ hybridization. These data suggest that the direct effect of HHV-6 on haematopoietic progenitors is one of the major causes of the suppression of thrombopoiesis.

Antigens, CD34↗
PubMed2000

Augmentation of basal insulin release from rat islets by preexposure to a high concentration of glucose.

We have found that preexposure to an elevated concentration of glucose reversibly induces an enhancement of basal insulin release from rat pancreatic islets dependent on glucose metabolism. This basal insulin release augmented by priming was not suppressed by reduction of the intracellular ATP or Ca(2+) concentration, because even in the absence of ATP at low Ca(2+), the augmentation was not abolished from primed electrically permeabilized islets. Moreover, it was not inhibited by an alpha-adrenergic antagonist, clonidine. A threshold level of GTP is required to induce these effects, because together with adenine, mycophenolic acid, a cytosolic GTP synthesis inhibitor, completely abolished the enhancement of basal insulin release due to the glucose-induced priming without affecting the glucose-induced increment in ATP content and ATP-to-ADP ratio. In addition, a GDP analog significantly suppressed the enhanced insulin release due to priming from permeabilized islets in the absence of ATP at low Ca(2+), suggesting that the GTP-sensitive site may play a role in the augmentation of basal insulin release due to the glucose-induced priming effect.

Adenosine Triphosphate↗
PubMed2000

Growth hormone therapy in achondroplasia.

Achondroplasia is one of the most common causes of severe rhizomelic dwarfism. We have previously reported the growth-promoting effect of growth hormone (GH) in this disorder. In this expanded clinical study, dose dependency and the long-term effect of GH were also investigated. Prepubertal children with achondroplasia (82 males and 63 females) were randomly divided into 2 groups. Patients were treated with 0.5 IU/kg per week or 1.0 IU/kg per week subcutaneous recombinant human GH. Of 75 patients, the mutational analysis of fibroblast growth factor receptor-3 revealed that G1138A was detected in 70 and G1138C was found in 2. GH increased growth rate and height z score in a dose-dependent manner. GH also increased serum insulin-like growth factor (IGF)-I, IGF-binding protein-3 and osteocalcin. No adverse effects were observed in either group. We conclude that GH therapy is a useful method for improvement of severe growth retardation of achondroplasia.

Achondroplasia↗
PubMed2000

Vitamin D is an important factor in estrogen biosynthesis of both female and male gonads.

In the present study, the role of vitamin D in the regulation of estrogen synthesis in gonads was investigated. Vitamin D receptor null mutant mice showed gonadal insufficiencies. Uterine hypoplasia and impaired folliculogenesis were observed in the female, and decreased sperm count and decreased motility with histological abnormality of the testis were observed in the male. The aromatase activities in these mice were low in the ovary, testis, and epididymis at 24%, 58%, and 35% of the wild-type values, respectively. The gene expression of aromatase was also reduced in these organs. Elevated serum levels of LH and FSH revealed hypergonadotropic hypogonadism in these mice. The gene expressions of estrogen receptor alpha and beta were normal in gonads in these mice. Supplementation of estradiol normalized histological abnormality in the male gonads as well as in the female. Calcium supplementation increased aromatase activity and partially corrected the hypogonadism. When the serum calcium concentration was kept in the normal range by supplementation, the aromatase activity in the ovary increased to 60% of the wild-type level, but LH and FSH levels were still elevated. These results indicated that vitamin D is essential for full gonadal function in both sexes. The action of vitamin D on estrogen biosynthesis was partially explained by maintaining calcium homeostasis; however, direct regulation of the expression of the aromatase gene should not be neglected.

Animals↗
PubMed2000

Effect of epinephrine on GLUT2 protein content in mouse liver.

The intraperitoneal administration of epinephrine (EP) to mice caused a significant increase in the blood glucose level and a significant decrease in the liver glycogen content 1 h after its administration at 0.6 mg/kg (blood glucose; p < 0.01, liver glycogen; p < 0.01). The liver type glucose transporter (GLUT2) mRNA expression and protein content from mouse liver significantly increased in the intraperitoneally EP-treated mice when compared to that in normal mice (mRNA; p < 0.01, protein; p < 0.01). These results suggest that the hyperglycemic effect of EP is due, at least in part, to the increase of GLUT2 protein synthesis.

Animals↗
PubMed2000

The effects of bone marrow transplantation on X-linked hypophosphatemic mice.

The genes responsible for X-linked hypophosphatemic (XLH) vitamin D-resistant rickets and the murine homolog, hypophosphatemic mice (Hyp), were identified as PHEX and Phex (phosphate-regulating gene with homology to endopeptidases on the X chromosome), respectively. However, the mechanism by which inactivating mutations of PHEX cause XLH remains unknown. We investigated the mechanisms by syngeneic bone marrow transplantation (BMT) from wild mice to Hyp mice. The expression of the Phex gene was detected in mouse BM cells. BMT introduced a chimerism in recipient Hyp mice and a significant increase in the serum phosphorus level. The renal sodium phosphate cotransporter gene expression was significantly increased. The effect of BMT on the serum phosphorus level depended on engraftment efficiencies, which represent the dosage of normal gene. Similarly, the serum alkaline phosphatase (ALP) activity was decreased and bone mineral density was increased. Furthermore, the renal expression of 25-hydroxyvitamin D3 24-hydroxylase, which is a key enzyme in the catabolic pathway and is increased in XLH/Hyp, was improved. From these results, we conclude that transplantation of normal BM cells improved abnormal bone mineral metabolism and deranged vitamin D metabolism in Hyp by replacing defective gene product(s) with normal gene product(s). This result may provide strong evidence for clinical application of BMT in metabolic bone disorders.

Alkaline Phosphatase↗
PubMed2000

Thyroid-stimulating antibody in a patient with euthyroid Graves' disease.

We report an 11-year-old girl with euthyroid Graves' disease. She was referred to our clinic because of left exophthalmos without other symptoms suggestive of hyperthyroidism. Her serum concentration of free thyroxine (FT4) and free triiodothyronine (FT3) were normal, but thyroid-stimulating hormone (TSH) was below normal and impaired TSH response to TSH releasing hormone (TRH) was found. Although the sera were positive for anti-TSH receptor antibody (TRAb) and thyroid-stimulating antibody (TSAb), both titers were not as high as usually observed in Graves' disease. Three months later, she developed hyperthyroidism and was treated with propylthiouracil. Within 2 weeks of the initiation of therapy, all symptoms except exophthalmos disappeared, and after 2 months of treatment TRAb was negative though TSAb remained positive. TSAb is therefore a good indicator to use in the diagnosis and follow-up of euthyroid Graves' disease and should be measured in patients with exophthalmos of unknown origin, even in children.

Antithyroid Agents↗
PubMed2000

The effect of calcium-sensing receptor gene polymorphisms on serum calcium levels: a familial hypocalciuric hypercalcemia family without mutation in the calcium-sensing receptor gene.

Familial hypocalciuric hypercalcemia (FHH) is a benign syndrome with elevated levels of serum calcium, relative hypocalciuria, and non-suppressed serum parathyroid hormone (PTH) levels. FHH usually occurs by a heterozygous mutation of the calcium sensing receptor (Casr), but some FHH patients show no mutations of the Casr. We encountered a unique FHH family in which the proband and her mother had many calcium deposits on their skin. The proband was medicated with Levothyroxine for hypothyroidism due to an iodine transport defect (ITD). We searched for mutation of the Casr, but found none. The only change distinguishing the proband and her mother from her father was at codon 990, reported to be a polymorphic site. We investigated the frequency of polymorphism at codon 990, but a significant relationship between the three genotypes and the serum calcium concentration was excluded. At the other polymorphic sites at codon 536, 926, 986, and 1011, polymorphisms were rare in Japanese, and we could not confirm a significant relationship. In conclusion, mutation in the Casr gene alone does not explain all cases of FHH. The other mechanisms should be identified.

Base Sequence↗
PubMed2000

A case of penetrating aortic atherosclerotic ulcer with hemoptysis.

A 69-year old Japanese woman with hypertension was admitted because of continuous back pain and recurrent hemoptysis. Radiographic findings showed an enhanced irregular mass, at the aortic arch fed by the tracheal artery, which implied both a penetrating aortic atherosclerotic ulcer and lung cancer. Diagnostic surgery revealed no evidence of cancer but did reveal a rupture of the intima at the distal part of the aortic arch. It is assumed that the transmural oozing occurred after development of the penetrating aortic ulcer, which formed an extra-aortic hematoma and caused surrounding inflammation, and led to tracheal artery feeding. The intramural hematoma might have weakened vascular wall tension from the aorta, and formed an oozing extra-aortic hematoma instead of an acute rupture.

Aged↗