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Biomedical subjects

Y Takei

Publications and source records attributed to Y Takei.

At least 181 records · Page 10Linked to original sources
PubMed1996

Whole body autoradiography and microautoradiography in eels after intra-arterial administration of 125I-labeled eel ANP.

125I-labeled eel atrial natriuretic peptide (ANP) was administered into the ventral or dorsal aorta of freshwater (FW) and seawater (SW) eels, Anguilla japonica, and the major target organs were explored by whole body autoradiography. Localization of the ANP binding in the target organs was also examined at tissue and cell levels by microautoradiography using tissue sections. Whole body autoradiography revealed that the specific label was accumulated predominantly in the gill, with lesser amounts in the atrium, kidney, liver, and urinary bladder. Autoradiographic grains were most dense in the secondary lamellae of the gill, particularly on the side of the efferent filamental artery. Other binding sites in target tissues were the glomerulus of the kidney, epicardium and endocardium of the atrium, bile duct/blood vessels of the liver, and interrenal cells of the head kidney. There was no difference in the distribution and density of grains between injections into the ventral aorta and dorsal aorta, although, in the former, injected 125I-labeled eel ANP passes through the gill before reaching peripheral target tissues. There was a tendency for downregulation of ANP binding sites in SW eels, especially in the gill. These results show that specific ANP binding sites are present in organs that are implicated in osmoregulation and cardiovascular regulation in eels and further suggest that the number of ANP binding sites varies according to changes in the environmental salinity.

Anguilla↗
PubMed1996

Serum levels of 3-deoxyglucosone and tissue contents of advanced glycation end products are increased in streptozotocin-induced diabetic rats with nephropathy.

To investigate a role of the Maillard reaction in the pathogenesis of diabetic nephropathy, we measured serum levels of 3-deoxyglucosone (3-DG), a potent protein cross-linking intermediate of the Maillard reaction, and tissue contents of advanced glycation end products (AGEs) in streptozotocin (STZ)-induced diabetic rats. We quantified serum 3-DG using gas chromatography/mass spectrometry, and measured AGE contents in tissues using a competitive enzyme-linked immunosorbent assay with a monoclonal anti-AGE antibody. The STZ-induced diabetic rats showed nephropathy with proteinuria, hypoproteinemia, hyperlipidemia and reduced creatinine clearance. Serum levels of 3-DG in the STZ-induced diabetic rats (mean +/- 3.46 +/- 0.23 mumol/l) were significantly (p < 0.01) higher than those in control rats (1.23 +/- 0.13 mumol/l). AGE contents in the kidney and the lens obtained from the STZ-induced diabetic rats (398 +/- 45 and 816 +/- 200 arbitrary units, respectively) were also significantly (p < 0.01) higher than those in the control rats (122 +/- 10 and 299 +/- 50 arbitrary units, respectively). The results indicate that increased levels of serum 3-DG and renal tissue. AGEs may be related to the occurrence of diabetic nephropathy.

Animals↗
PubMed1996

Identification of basic fibroblast growth factor-like immunoreactivity in panax ginseng extract: investigation of its molecular properties.

Basic fibroblast growth factor (bFGF)-like immunoreactivity was detected in extracts of Panax ginseng root by using a sensitive two-site enzyme immunoassay specific for human bFGF (hbFGF). In an investigation of the molecular properties of this bFGF-like molecule (bFGF-LI), the bFGF-LI and hbFGF were found to be equivalent with respect to antigenicity, molecular weight, isoelectric point, affinity for binding to heparin, and mitogenic activity toward BALB/c3T3 fibroblasts. The identification of this bFGF-LI molecule in Panax ginseng root helps to explain various activities of the traditional Chinese medicine ginseng.

3T3 Cells↗
PubMed1996

Effect of eel ventricular natriuretic peptide on the kidney and cardiovascular system in the dog.

Ventricular natriuretic peptide (VNP), a possibly new type of natriuretic peptide with an extended C-terminal tail, has been isolated from eel cardiac ventricles. We investigated the effects of eel VNP on the kidney and cardiovascular system and compared these results with those of mammalian peptides in dogs. Eel VNP, human (dog) ANP, human and dog BNPs were infused into the renal artery at non-hypotensive doses. All peptides produced similar diuresis and natriuresis, but cardiac output and the left and right ventricular stroke work were decreased by BNPs, but ANP and eel VNP did not change these parameters. Systemic vascular resistance was increased by BNPs, but unaffected by other peptides. These results show that eel VNP has renal effects similar to ANP and BNP, but it elicits responses in the heart different from those of BNPs in anesthetized dogs.

Animals↗
PubMed1996

Osmotic and volaemic regulation of atrial and ventricular natriuretic peptide secretion in conscious eels.

The effects of acute manipulation of plasma osmolality and blood volume on plasma atrial and ventricular natriuretic peptide (ANP and VNP) levels were examined in conscious freshwater eels, Anguilla japonica. A bolus injection of hypertonic NaCl (0.85 M and 1.7 M, 2.5 ml/kg body weight) through a catheter into the ventral aorta produced increases in plasma Na concentration and osmolality with parallel concentration-dependent, transient increases in plasma ANP and VNP levels. Plasma ANP and VNP levels also increased after injection of 1.7 M mannitol solution which produced an increase in plasma osmolality but a decrease in plasma Na concentration. However, injection of a 2.0 M solution of urea, which does not cause cellular dehydration in mammals, produced only small increases in plasma ANP and VNP levels, although plasma osmolality increased. A bolus injection of 10 or 25 ml/kg isotonic saline supplemented with 2% dextran for colloidal osmotic pressure, which theoretically increased blood volume by 29% or 71%, produced volume-dependent, transient increases in plasma ANP and VNP levels without changes in plasma Na concentration and osmolality. Similar volume expansion with dialysed eel plasma caused greater increases than with dextran-saline. However, these increases were much smaller than those after osmotic stimuli. These results indicate that secretion of ANP and VNP is regulated by two receptor mechanisms: osmo-receptors activated by cellular dehydration, not specifically by hypernatraemia, and volume or stretch receptors activated by hypervolaemia. The relative importance of the osmoreceptive mechanism is greater in eels than in mammals where volaemic regulation dominates over osmotic regulation for ANP secretion.

Anguilla↗
PubMed1995

Cloning and properties of a novel natriuretic peptide receptor, NPR-D.

A novel natriuretic peptide receptor, which we have termed natriuretic peptide receptor D (NPR-D), has been cloned and characterized. cDNAs related to the natriuretic peptide receptor (NPR) were amplified by PCR from a template of poly(A)-rich RNA isolated from the eel gill. Sequencing of the PCR products revealed the presence of a new clone that showed about 70% sequence identity to the eel type-C receptor, NPR-C. The PCR fragment was used to determine the tissue distribution of the new NPR-D message by an RNase protection assay, which gave the strongest signal in brain samples, and then used to screen a brain library to obtain a full-length cDNA clone. The cDNA clone predicted a protein of 500 amino acids containing a signal sequence and a hydrophobic transmembrane segment. The predicted sequence also contained the NPR motif which is essential for the binding of natriuretic peptides. The protein NPR-D was expressed in COS cells and shown to have high affinities for eel and rat natriuretic peptides. The newly cloned NPR-D has a short cytoplasmic tail; in this respect, NPR-C and NPR-D are very similar and form a subfamily of the NPR family. Affinity labeling indicated that NPR-D exists as a disulfide-linked tetramer. This is a marked contrast to the homodimeric structure of NPR-C. HS-142-1, a non-peptide natriuretic peptide receptor antagonist of microbial origin previously shown to be selective for the guanylate-cyclase-coupled receptors NPR-A and NPR-B, competitively inhibited the binding of 125I-labeled eel natriuretic peptide to eel NPR-D, whereas it did not affect the binding activity of eel NPR-C, suggesting that HS-142-1 is an antagonist that recognizes the tetrameric structures of NPR since the guanylate-cyclase-coupled receptors have also been demonstrated to exist as tetramers.

Amino Acid Sequence↗
PubMed1995

Cloning, functional expression and tissue distribution of human alpha 1c-adrenoceptor splice variants.

We report the cloning and characterization of two isoforms of human alpha 1c-adrenoceptor cDNA (alpha 1c-2, alpha 1c-3). These isoforms are generated by alternative splicing and differ from the clone we previously isolated (alpha 1c-1) in their length and sequences of the C-terminal domain. Tissue distribution of mRNAs showed that these variants co-express with alpha 1c-1 in the human heart, liver, cerebellum and cerebrum. Despite the structural differences, functional experiments in transfected CHO cells showed that the three isoforms have similar ligand binding properties, and all couple with phospholipase C/Ca2+ signaling pathway.

Alternative Splicing↗
PubMed1995

Antioxidative activity of quercetin and quercetin monoglucosides in solution and phospholipid bilayers.

The antioxidative effect of quercetin, quercetin 3-O-beta-D-glucopyranoside (Q3G), quercetin 4'-O-beta-D-glucopyranoside (Q4'G) and quercetin 7-O-beta-D-glucopyranoside (Q7G) was examined in solution and liposomal phospholipid suspension. First, their peroxyl radical-scavenging activities were investigated by measuring the inhibition of hydroperoxidation of methyl linoleate initiated by a radical initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). Quercetin exhibited the highest peroxyl radical-scavenging activity judging from the rate of hydroperoxidation during the induction period (Rinh) and the length of induction period (tinh). Although Q7G showed an induction period, its Rinh was higher and its tinh was lower than that of quercetin. Neither Q3G nor Q4'G gave a clear induction period in the curve of hydroperoxide formation. The rate of hydroperoxidation in the presence of Q3G was higher than Rinh of quercetin and the oxidative loss of Q3G was much slower than quercetin or Q7G when exposed to AMVN in solution. Q4'G exerted little inhibition compared to Q3G or Q7G. Next, the antioxidative activity of quercetin and its monoglucosides in phospholipid bilayers was examined by measuring the inhibition of lipid peroxidation in large unilamellar vesicles composed of egg yolk phosphatidylcholine (PC) and a water-soluble radical initiator. They retarded the accumulation of PC-hydroperoxides and the induction period increased in the order of Q4'G < Q3G approximately Q7G < quercetin. It is therefore concluded that quercetin acts as an antioxidant more efficiently than its monoglucosides when phospholipid bilayers are exposed to aqueous oxygen radicals.

Antioxidants↗
PubMed1995

Cloning, properties, site-directed mutagenesis analysis of the subunit structure, tissue distribution and regulation of expression of the type-C eel natriuretic peptide receptor.

Eel natriuretic peptide receptor C (NPR-C) was cloned, characterized and found to have a unique interchain disulfide linkage when compared to that of mammalian NPR-C. The NPR-C cDNA was obtained from an eel gill cDNA library; the open reading frame codes for a polypeptide of 502 amino acids exhibiting the known features of NPR-C, including a weak ligand specificity and a disulfide-linked homodimeric structure. The deduced amino acid sequence shares approximately 60% similarity with the mammalian NPR-C but it lacks the Gly-rich prosequence present in the mammalian counterparts. Site-directed mutagenesis revealed that eel and mammalian NPR-C are quite different in their interchain disulfide-bonding pattern; eel uses the second Cys residue and mammals the fifth Cys residue for the covalent dimerization. The ligand-binding activity of the extracellular domain is not independent of the short cytoplasmic tail. RNase protection analysis revealed that the eel receptor is highly expressed in the gill and heart and, to a much lesser extent, in other tissues including the brain and intestine. The NPR-C mRNA levels were found to be down-regulated in most tissues when eels were transferred from fresh water to seawater; however, in the anterior intestine, the levels were up-regulated, suggesting that NPR-C plays a role in the adaptation to salinity changes in the euryhaline eel.

Amino Acid Sequence↗
PubMed1995

Improvement of an EIA system for basic fibroblast growth factor by use of biotinylated antibody prepared with NHS-LC-biotin.

We improved our previously devised enzyme immunoassay (FIA) system for basic fibroblast growth factor (bFGF) using biotinylated antibody prepared with sulfosuccinimidyl-6-(biotinamido)hexanoate (NHS-LC-Biotin, Pierce), a water-soluble biotin analogue, with an extended spacer arm. The discriminatory detection limit of the improved EIA was found to be 5 pg/ml (0.5 pg/assay tube), sixfold more sensitive than that of the previous system. The reproducibility of within- and between-assay series was 5.10-8.61% and 5.99-8.69%, respectively; and recovery of exogenous bFGF from serum was approximately 102%. Employing the improved EIA system, we investigated by chromatofocusing chromatography the isoelectric points of two immunoreactive bFGFs (high-molecular-weight bFGF-like immunoreactive substance, designated as HMW-bFGF-LI and 16-kd bFGF-LI, having the same molecular weight as recombinant bFGF) detected in serum from a breast cancer patient. As a result, the pI value of HMW-bFGF-LI was estimated to be 7.13, and that of 16 kd bFGF-LI, 9.58.

Adult↗
PubMed1995

Reassessment of the two-site enzyme immunoassay for human epidermal growth factor (hEGF) and measurement of immunoreactive hEGF in human sera and urine.

We reassessed the enzyme immunoassay (EIA) system for hEGF previously developed by our laboratory (Clin Chim Acta 156:51-60, 1985), since it appeared that the reported EIA system detected not only hEGF but also pS2 protein owing to minor contamination by pS2 protein in the hEGF sample used for immunization. In this study, we purified the hEGF sample using Benzamidine-Sepharose 6B column chromatography as a critical step for purification and newly developed an EIA system with specificity for hEGF. We also measured the hEGF level in serum, plasma, and urine from normal subjects by our new EIA system and found that the values measured by the previous system were 1.2-5.8-fold higher than the new system values. These results suggest that the previous system detected "hEGF" in excess owing to the nonspecificity of the antibody used. We investigated the molecular nature of immunoreactive hEGF detected in serum using our new system and confirmed that considerable amounts of immunoreactive hEGF exist as a high molecular weight form through S-S linkage with some macromolecule(s) in human blood as reported previously (Biochem Int 12:677-683, 1986).

Adult↗
PubMed1995

Multiple mitochondrial DNA deletions in a patient with mitochondrial myopathy and cardiomyopathy but no ophthalmoplegia.

Deletions of muscle mitochondrial DNA are known in mitochondrial myopathy patients who have chronic progressive external ophthalmoplegia (CPEO). A 41-year-old patient with no apparent family history of this condition suffers from hypertrophic cardiomyopathy, slight muscle atrophy, and weakness of the extremities, but not from CPEO. A muscle biopsy showed the presence of ragged-red fibers, and Southern blot analysis disclosed multiple deletions of muscle mitochondrial DNA. This combination of clinical features in our patient is atypical in mitochondrial myopathy with demonstrable deleted muscle mitochondrial DNA. Pleomorphic clinical expression is suggested.

Adult↗
PubMed1995

Colonic mucosal hemodynamics and tissue oxygenation in patients with ulcerative colitis: investigation by organ reflectance spectrophotometry.

Colonic mucosal hemodynamics were investigated at the rectosigmoidal region of the colon in 46 patients with ulcerative colitis and in 18 normal subjects by organ reflectance spectrophotometry under colonoscopy. The value for the index of mucosal hemoglobin concentration (IHb) was significantly higher, and value for the index of mucosal hemoglobin oxygen saturation (ISO2) was significantly lower in patients with active ulcerative colitis than values in the normal controls or in patients with inactive ulcerative colitis. The results indicate mucosal congestion and hypoxemia in patients with active ulcerative colitis. The changes in IHb and ISO2 correlated well with the severity of ulcerative colitis scored by endoscopic findings and with the number of infiltrating inflammatory cells in the mucosa analyzed histologically in biopsy samples. In conclusion, the colonic mucosal microcirculation in patients with active ulcerative colitis was disturbed and showed congestion and hypoxemia. The analysis of hemodynamic changes may be helpful for assessing the activity of ulcerative colitis.

Adult↗
PubMed1995

Endogenous nitric oxide modulates ethanol-induced gastric mucosal injury in rats.

BACKGROUND/AIMS: Endothelium-derived relaxing factor regulates vascular tone via vasodilation. The relative contribution of endogenous nitric oxide to the pathophysiology of ethanol-induced gastric mucosal microcirculatory disturbances was investigated in anesthetized rats. METHODS: Macroscopic and microscopic gastric mucosal damage and gastric mucosal hemodynamics including blood flow and hemoglobin oxygen saturation (ISO2) were assessed by pretreatment with a specific NO synthase inhibitor, N omega-nitro-L-arginine (L-NNA), before and after intragastric administration of ethanol. RESULTS: Pretreatment with L-NNA significantly increased macroscopic (7.7-fold) and microscopic damage caused by 30% ethanol. Concurrent administration of L-arginine, but not D-arginine, significantly reduced the increase in mucosal damage. Similar results were obtained with 60% ethanol. Pretreatment with L-NNA decreased both mucosal blood flow and ISO2 in the basal period and enhanced decreases in both mucosal blood flow (2.7-fold) and ISO2 (4.3-fold) induced by 30% ethanol compared with controls. Concurrent administration of L-arginine, but not D-arginine, significantly inhibited the effect of L-NNA on blood flow and ISO2 in the basal period as well as after intragastric administration of 30% ethanol. CONCLUSIONS: Endogenous NO modulates ethanol-induced gastric mucosal injury through the regulation of gastric mucosal microcirculation.

Animals↗
PubMed1995

Immunohistochemical detection of advanced glycation end products in dialysis-related amyloidosis.

beta 2-Microglobulin (beta 2m) isolated from the amyloid deposits in patients with dialysis-related amyloidosis (DRA) has been demonstrated to be modified with advanced glycation end products (AGE). We produced a monoclonal anti-AGE antibody which localized AGE to amyloid deposits in patients with DRA by immunohistochemistry. The connective tissues in the carpal tunnel were obtained from surgical specimens in six patients with DRA. AGE were localized to the beta 2m-positive amyloid deposits in these patients using the monoclonal anti-AGE antibody. AGE were also detected in infiltrating cells surrounding the amyloid deposits. The AGE-positive cells were identified as macrophages, since they showed positive staining with anti-CD68 antibody. In conclusion, AGE were demonstrated by immunohistochemical technique to be present in both beta 2m-positive amyloid deposits and surrounding macrophages in patients with DRA.

Adult↗
PubMed1995

Simultaneous analysis of mucosal and submucosal hemodynamics using infrared electronic endoscopy: effects of intraluminal acid on ulcer scars.

BACKGROUND AND STUDY AIMS: This report describes the use of an infrared electronic endoscope for the assessment of gastric mucosal and submucosal hemodynamics in ulcer scars. METHODS: The experimental ulcer scars were induced by acetic acid injection in five anesthetized dogs. Indices of mucosal hemoglobin content (IHb) and its oxygenation (ISO2) were calculated from reflectance spectra of the mucosa at 569, 577, 586, and 650 nm, which were obtained through an optic probe. The gastric submucosal vascular diameter was assessed by comparison with a reference wire under infrared endoscopic observation. RESULTS: The index of mucosal hemoglobin content measured by reflectance spectrophotometry was significantly higher at the ulcer scars than in the intact mucosa before the ulcer induction. Intraluminal administration of 0.2 N hydrochloric acid lowered IHb and ISO2 only at the ulcer scars. The diameters of the gastric submucosal veins beneath the ulcer scars decreased markedly after the acid administration. CONCLUSION: The results suggest abnormal responses of gastric mucosal and submucosal circulation at ulcer scars to intraluminal acid. Infrared electronic endoscopy is therefore a useful tool for the simultaneous analysis of mucosal and submucosal circulation in the stomach.

Animals↗