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Biomedical subjects

F Umeda

Publications and source records attributed to F Umeda.

At least 37 records · Page 2Linked to original sources
PubMed1998

Subcutaneous or visceral adipose tissue expression of the PPARgamma gene is not altered in the fatty (fa/fa) Zucker rat.

We cloned 537 basepairs (bp) of rat partial peroxisome proliferator-activated receptor gamma2 (PPARgamma2) cDNA and examined the effect of fasting or obesity on the expression of two isoforms of rat PPARgamma, gamma1 and gamma2, in either subcutaneous or mesenteric adipose tissue specimens using an RNase A protection assay. In Wistar rats, expression of both isoforms was dramatically reduced after 48 hours of fasting in the two fat tissue specimens. In comparing genetically obese (fa/fa) Zucker rats and lean control rats, no significant difference was observed in expression of the two isoforms in either type of adipose tissue. From these findings, we conclude that the adipose tissue level of rat PPARgamma depends on nutritional deprivation but is not closely associated with either obesity or insulin resistance in obese Zucker rats.

Adipose Tissue↗
PubMed1998

High glucose induces alteration of gap junction permeability and phosphorylation of connexin-43 in cultured aortic smooth muscle cells.

Gap junction is thought to have a crucial role in maintaining tissue homeostasis. We examined the effect of a high glucose level on gap junctional intercellular communication (GJIC) activity in cultured vascular smooth muscle cells (VSMCs) using the fluorescent dye transfer method. After a 48-h incubation with 22 mmol/l glucose (high glucose level), GJIC activity of VSMCs was significantly reduced compared with incubation with 5.5 mmol/l glucose (normal glucose level) (P < 0.05). Treatment of the cells with 12-O-tetradecanoylphorbol-13-acetate (TPA; 5 x 10(-8) mol/l), a protein kinase C (PKC) activator, for 1 h also reduced GJIC activity (P < 0.01). In addition, treatment of the cells with calphostin C, a specific PKC inhibitor, for 3 h completely restored the GJIC activity inhibited by the high glucose level. Western blot analysis showed that connexin 43 (Cx43), which is the major functional protein of gap junction, is present in multiphosphorylated forms: a nonphosphorylated form (P0) and phosphorylated forms (P1, P2, and P3). Incubation of VSMCs with a high glucose level significantly increased the density ratio of P3/P0 compared with a normal glucose level (P < 0.05). Similarly, treatment of the cells with TPA significantly increased the P3/P0 ratio compared with controls (P < 0.01). In addition, the increase in the P3/P0 density ratio induced by a high glucose level was restored to the control level by both staurosporine and calphostin C. These results suggest that the high glucose level induced the inhibition of GJIC activity in cultured VSMCs through excessive phosphorylation of Cx43, mediated by PKC activation. This may contribute to the development of the macroangiopathy associated with diabetes.

Animals↗
PubMed1997

Effect of acarbose on glucose intolerance in patients with non-insulin-dependent diabetes mellitus.

We evaluated the effect of acarbose, an alpha-glucosidase inhibitor, on glucose intolerance in patients with non-insulin-dependent diabetes mellitus (NIDDM). Acarbose was given orally (300 mg/day) for 24 weeks to 20 NIDDM patients. Data in an oral glucose tolerance test (OGTT) were evaluated before and after 24 weeks of treatment using principal component analysis. Acarbose administration significantly reduced the postprandial plasma glucose level over 24 weeks of treatment. Principal component analysis suggested that the patients were separated into responders and non-responders. There was a significant improvement of fasting and postprandial glucose levels after 12 and 24 weeks in the responders, but not in the non-responders. Plasma glucose level following the OGTT improved significantly after 24 weeks of treatment in the responders (Hotelling T2 value = 47.098, P = 0.022500), but not in the non-responders. The immunoreactive insulin level did not change in either group. Results thus suggest that acarbose improved insulin resistance in some patients with NIDDM (responders as classified by principal component analysis).

Acarbose↗
PubMed1997

Difference in serum-induced prostacyclin production by cultured aortic and capillary endothelial cells.

Prostacyclin (PGl2) generated by vascular endothelial cells play an important role in the maintenance of vessel wall homeostasis. Human plasma-derived serum (PDS) stimulated PGl2 synthesis by both cultured bovine aortic endothelial cells (BAEC) and adrenal capillary endothelial cells (BCEC), but the PGl2 response of the latter cells was far smaller. When BAEC were cultured with a high concentration of glucose (400 mg/dl), the PGl2 synthesis induced by 20% PDS was significantly lower than in the culture with a physiological concentration of glucose (100 mg/dl) (258 +/- 45 pg/10(4) cells/h vs. 402 +/- 52 pg/10(4) cells/h, n = 4, P < 0.05). On the other hand, there was no significant difference in the PDS-induced PGl2 synthesis between BCEC cultured with high and physiological concentrations of glucose. Additionally, 10% PDS obtained from patients with non-insulin dependent diabetes mellitus (n = 6) stimulated significantly less PGl2 synthesis than that from healthy subjects (n = 4) in the case of both BAEC (133 +/- 27 pg/10(4) cells/h vs. 402 +/- 38 pg/10(4) cells/h, P < 0.05) and BCEC (72 +/- 15 pg/10(4) cells/h vs. 118 +/- 12 pg/10(4) cells/h, P < 0.05), with the difference in PGl2 synthesis being smaller for BCEC. These findings indicate that the PDS-induced PGl2 synthesis differs between cultured vascular endothelial cells from large and small vessels with the decrease in PGl2 by diabetic PDS and high glucose being more marked for BAEC than BCEC.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Human diploid fibroblast cell culture medium contains a factor that increases cytosolic Ca2+ and stimulates prostaglandin synthesis by cultured bovine aortic endothelial cells.

Previously, we demonstrated that conditioned medium (CM) from cultures of human diploid fibroblast cells contains a factor that stimulates the production of prostacyclin (PGI2) by cultured bovine aortic endothelial cells (BAEC). To study the mechanism by which CM stimulates PGI2 production, we measured the effect of removal of extracellular calcium (Ca2+) on the concentration of cytosolic Ca2+ and on the production of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), a stable metabolite of PGI2. The CM-induced production of 6-keto-PGF1 alpha was dependent on extracellular Ca2+ and did not require nascent protein synthesis. Application of CM to BAEC induced a transient increase in cytosolic Ca2+ concentration that was dependent on extracellular Ca2+. Bradykinin induced the production of 6-keto-PGF1 alpha by BAEC. However, bradykinin induced an increase in cytosolic Ca2+ concentration in the presence or absence of extracellular Ca2+. Voltage dependent Ca2+ channel blocker (verapamil, diltiazem) did not inhibit either the CM-induced increase in cytosolic Ca2+ or the production of 6-keto-PGF1 alpha by BAEC. These data suggest that CM increases the cytosolic Ca2+ concentration and stimulates PGI2 production by BAEC. The increase in cytosolic Ca2+ concentration occurred via the influx of extracellular Ca2+ independent of L-type Ca2+ channels blocked by verapamil or diltiazem.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Persistence of cyclopiazonic acid-induced endothelium-dependent vasodilatation in spontaneously hypertensive and streptozotocin-induced diabetic rats.

We recently reported that cyclopiazonic acid (CPA) releases a novel endothelium-derived relaxing factor that is not prostacyclin, nitric oxide or endothelium-derived hyperpolarizing factor in rat mesenteric arterial bed. The acetylcholine-induced vasodilatation of the isolated mesenteric bed in spontaneously hypertensive rats (SHR) was not different from that in Wistar Kyoto rats (WKY), but it was significantly smaller in streptozotocin (STZ)-induced diabetic rats than in age-matched controls. The CPA-induced vasodilatation was not affected in SHR or in STZ-induced diabetic rats. These results suggest that the CPA-induced endothelium-dependent vasodilatation is resistant to the effects of diabetes.

Acetylcholine↗
PubMed1997

A case of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes associated with diabetes mellitus and hypothalamo-pituitary dysfunction.

A 45-year-old woman with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) had muscular atrophy, severe cerebral and cerebellar atrophy, and cardiac hypertrophy. She also had diabetes mellitus treated with insulin, and sensorineural hearing loss. Ragged-red fibers were observed on muscle biopsy and an adenine to guanine transition mutation at position 3243 of her mitochondrial DNA was confirmed. Further investigations revealed that she also had hypothalamo-pituitary dysfunction. It appears that diabetes mellitus, hypothalamo-pituitary dysfunction, and the other abnormalities are all associated with mitochondrial dysfunction in this patient.

Atrophy↗
PubMed1997

Immunohistochemical study of prostacyclin-stimulating factor (PSF) in the diabetic and atherosclerotic human coronary artery.

Prostacyclin (PGI2) synthesis by vascular endothelial cells (ECs) decreases in diabetic subjects, possibly leading to the development of diabetic angiopathy, such as that seen in atherosclerosis. We recently found a novel bioactive peptide, prostacyclin-stimulating factor (PSF), which stimulates PGI2 synthesis by cultured aortic ECs. Our previous studies demonstrated that PSF is dominantly expressed by arterial smooth muscle cells (SMCs). In the present study, we found PSF to exist in the SMCs of human coronary arteries by means of immunohistochemical methods. Human coronary arteries obtained from autopsies were divided into four subgroups, with or without NIDDM and/or myocardial infarction. Immunostaining for PSF was performed by the avidin-biotin peroxidase complex method using a purified anti-PSF antibody, and the immunostaining for PSF was assessed semiquantitatively. PSF staining was markedly reduced in coronary arterial SMCs from patients with NIDDM and/or myocardial infarction. In addition, the effect of a high glucose culture on PSF mRNA expression and PSF production in bovine aortic SMCs was examined by immunocytochemical staining and both Western and Northern blot analyses. The immunostaining and immunoblot band for PSF also significantly decreased when bovine aortic SMCs were cultured with high concentrations of glucose. Furthermore, as compared with the SMCs cultured with a physiological glucose concentration, the density ratio of PSF mRNA to 28S rRNA expression significantly decreased when the SMCs were cultured with high concentrations of glucose. These results strongly suggest that the decreased PSF production may thus results in a decreased production of PGI2 in the coronary artery, thus leading to the development of both diabetic macroangiopathy and atherosclerosis.

Adult↗
PubMed1997

[Insulin secretin and resistance accompany immobilization of the aged patient].

Physical activity is known to increase glucose tolerance and insulin sensitivity. To examine the influence of physical inactivity on insulin sensitivity in aged people, insulin sensitivity and secretion was measured by using a two-step euglycemic glucose clamp, a glucagon tolerance test (GTT), an oral glucose tolerance test (OGGT) and urinary CPR excretion in 11 aged patients immobilized in bed for more than 12 weeks. The results were compared with those of nine healthy mobile aged controls. The muscle volume of the immobilized patients decreased by 20-25% compared with that of the controls, and insulin sensitivity decreased 50% in each step. These results mean that the immobilized patients had decreased insulin sensitivity and responsiveness, even when there was muscle atrophy. The glucose and insulin responses in both the GTT and OGTT showed that there was a slight decrease in the initial response of insulin in the immobilized patients and was in the controls compared with adolescent controls. There was no difference in the initial response of insulin between the immobilized patients and the aged controls. The ratio of impaired glucose tolerance in the OGTT was 4/11 of the immobilized patients and 3/9 of the controls. Total insulin secretion was increased and insulin sensitivity and responsiveness was decreased in the immobilized patients. This suggests that the decreased insulin sensitivity was compensated for increased by insulin secretion in the immobilized patients.

Aged↗
PubMed1997

Elevated L-kynurenine level and its normalization by prednisolone in a patient with eosinophilia-myalgia syndrome.

We report a L-tryptophan-induced case of eosinophilia-myalgia syndrome in a Japanese woman and describe the time course of changes in tryptophan metabolism observed during steroid therapy. She had taken 1.0 g of the implicated L-tryptophan daily. When admitted due to painful swelling of her extremities, eosinophil count was 22.3 x 10(9)/L. Before prednisolone treatment, her serum L-kynurenine level was 10.2 mumol/L, a level about three-fold higher than the normal value, while serum tryptophan level was abnormally low (23.1 mumol/L). On the 14th day of prednisolone treatment (40 mg daily), L-kynurenine was declined to 8.1 mumol/L and, concomitantly, L-tryptophan level increased to the normal range (51.0 mumol/L). Subsequently, on the 42nd day of therapy, serum L-kynurenine was normalized. In contrast, serum serotonin level was unchanged throughout the course of this therapy. Prednisolone dramatically reduced the elevated serum L-kynurenine with a reciprocal increase in serum L-tryptophan indicates that abnormal tryptophan metabolism, may play a role in the pathogenesis of eosinophilia myalgia syndrome, and that the observed effect of steroid treatment was due to suppression of elevated activity of indoleamine 2, 3-dioxygenase, a first rate-limiting enzyme of the kynurenine pathway.

Anti-Inflammatory Agents↗
PubMed1997

Effect of beraprost sodium on the increased transendothelial permeation of albumin induced by high concentration of glucose.

To determine whether a decrease in prostacyclin production is involved in the increase in endothelial permeability induced by a high concentration of glucose, we evaluated the effect of beraprost sodium, a stable prostacyclin analog, on the transendothelial permeation of albumin in cultured aortic cells. Permeation of albumin across an endothelial cell monolayer was significantly greater when the cells were cultured with a high concentration of glucose (400 or 800 mg/dl) than when they were cultured with 100 mg/dl glucose. No significant change in the permeation of albumin was observed when cells were cultured with 100 mg/dl glucose as compared with 100 mg/dl glucose plus 700 mg/dl mannitol. The addition of beraprost sodium to the culture medium completely restored the increase in the permeation of albumin brought about by 400 mg/dl glucose. These results suggest that increased transendothelial permeation of albumin by high glucose may be due in part to a decrease in prostacyclin production by the endothelial cells. Beraprost sodium may restore the endothelial barrier function affected by a high concentration of glucose.

Albumins↗
PubMed1996

Effect of beraprost sodium on response to tests of autonomic control of heart rate in patients with diabetes mellitus.

Prostaglandin I2 (PGI2) produces greater vasodilating and anti-platelet effects than PGE1, but is chemically unstable. Beraprost sodium, a stable analog of PGI2, was given orally, 120 micrograms daily for 12 weeks, to 15 patients with non-insulin-dependent diabetes mellitus to evaluate its effect on autonomic function. The effect of the drug on heart rate (HR) was evaluated in response to standing, rest, and deep breathing. The drug had a significant effect on HR in response to standing, but not during rest or deep breathing. Nine patients without preproliferative or proliferative retinopathy, and in whom factor analysis suggested the drug was effective with respect to autonomic nerve dysfunction, showed a significant improvement in their response to the three tests after beraprost administration for 12 weeks. Blood glucose was unaffected. Results thus indicate that beraprost sodium alleviates autonomic nerve dysfunction in diabetic patients in the absence of severe retinopathy.

Adult↗
PubMed1996

Isolation and characterization of the human chromosomal gene for prostacyclin-stimulating factor.

Prostacyclin-stimulating factor (PSF) is a protein which acts on vascular endothelial cells and stimulates the production of prostacyclin. Recently, we were able to purify PSF from the conditioned medium of cultured human diploid fibroblasts and clone PSF cDNA. In this study, we screened a human genomic library and isolated genomic clones to determine the structure of the human chromosomal PSF gene. By determining the nucleotide sequence and transcription initiation site of this gene, we found that it comprises 5 exons and 4 introns. Southern hybridization analysis indicated the presence of a single copy of the PSF gene per haploid set of chromosomes. The 300 bp upstream of the transcription initiation site had a very high GC content, and 7 binding sites for the transcription regulating factor Sp1 were present.

Base Sequence↗
PubMed1996

Possible existence of novel endothelium-derived relaxing factor in the endothelium of rat mesenteric arterial bed.

Both acetylcholine (ACh) and cyclopiazonic acid (CPA) caused vasodilation of the mesenteric arterial bed in a concentration-dependent manner. When the mesenteric arterial bed was perfused with 0.1% Triton X-100 for 30 s, ACh- or CPA-induced vasodilation was almost abolished. ACh-induced vasodilation was significantly attenuated in isotonic high K+ (60 mM) solution and significantly decreased by treatment with methylene blue (MB) with NG-nitro-L-arginine (L-NNA) in isotonic high K+ (60 mM) solution, whereas CPA-induced vasodilation of the mesentery was not affected by these treatments. ACh- or CPA-induced vasodilation was not affected by indomethacin. ACh caused significant increase in cyclic GMP levels and cyclic AMP in effluents from the perfused mesentery, whereas CPA could not increase cyclic GMP. CPA caused significant increase in cyclic AMP in a concentration-dependent manner, and CPA-induced increase in cyclic AMP was completely inhibited by removal of the endothelium. These results suggest that one or more endothelium-derived relaxing factor (EDRF) or factors should exist other than endothelium-derived nitric oxide (EDNO) or endothelium-derived hyperpolarizing factor (EDHF) in the endothelium of the rat mesenteric arterial bed. The novel EDRF may relax the mesenteric arterial bed through production of cyclic AMP but not cyclic GMP.

Acetylcholine↗
PubMed1996

Biosynthesis of Poly(3-Hydroxyalkanoic Acid) Copolymer from CO(inf2) in Pseudomonas acidophila through Introduction of the DNA Fragment Responsible for Chemolithoautotrophic Growth of Alcaligenes hydrogenophilus.

Pseudomonas acidophila is a bacterial strain producing a poly(3-hydroxyalkanoic acid) (PHA) copolymer from low-molecular-weight organic compounds such as formate and acetate. The genes responsible for PHA production were cloned in cosmid pIK7 containing a 14.8-kb HindIII fragment of P. acidophila DNA. With the aim of developing a means of producing a PHA copolymer from CO(inf2), cosmid pIK7 was introduced into a polymer-negative mutant of the chemolithoautotrophic bacterium Alcaligenes eutrophus PHB(sup-)4. However, the recombinant strain produced a homopolymer of 3-hydroxybutyric acid (polyhydroxybutyric acid) from CO(inf2). Since it was thought that the composition of the accumulated polymer might depend not on the PHA biosynthetic genes but on the metabolism of the host strain, a recombinant plasmid, pFUS, containing the genes for chemolithoautotrophic growth of the hydrogen-oxidizing bacterium A. hydrogenophilus was introduced into P. acidophila by conjugation. The recombinant plasmid pFUS was stably maintained in P. acidophila in the absence of chemolithoautotrophic or antibiotic selection. This pFUS-harboring strain possessed the ability to grow under a gas mixture of H(inf2), O(inf2), and CO(inf2) in a mineral salts medium, and PHA copolymer accumulation was confirmed by nuclear magnetic resonance spectral analysis. A gas chromatogram obtained by gas chromatography-mass spectrometry showed the composition of the polymer to be 52.8% 3-hydroxybutyrate, 41.1% 3-hydroxyoctanoate, and 6.1% 3-hydroxydecanoate. This is the first report of the production of a PHA copolymer from CO(inf2) as sole carbon source.

Journal Article↗
PubMed1996

Prostacyclin-stimulating factor, novel protein, and diabetic angiopathy.

We recently purified and cloned a new protein that stimulates the synthesis of prostacyclin (PGI2) by the vascular endothelial cells (ECs). We have termed this protein "PGI2-stimulating factor" (PSF). The present study evaluated the expression of PSF mRNA in tissues of Wistar rats, including the kidneys of rats with streptozotocin-induced diabetes, and in cultured cells. Furthermore, we evaluated the presence of PSF in human sera and the immunohistochemical localization of PSF in tissues of patients obtained at autopsy. The latter included a coronary atherosclerotic lesion of a patient who died of acute myocardial infarction. PSF was observed by Northern blot analysis to be expressed in all rat tissues examined (brain, lung, liver, kidney, skeletal muscle, and fat tissue) and was expressed in cultured vascular ECs, smooth muscle cells (SMCs), and fibroblast cells (FCs). A decreased expression of PSF was observed in the kidneys of diabetic rats versus those of normal rats. The presence of PSF in human serum was confirmed by Western blot analysis. In humans, PSF was mainly localized in vascular ECs and SMCs of arterial media and in SMCs of bronchi. Reduced staining for PSF was found in an atherosclerotic versus a normal coronary artery of humans. PSF may be involved in the production of PGI2 in the vessel wall and may participate in the maintenance of vascular homeostasis. PSF abnormalities may be involved in the development of such vascular lesions as atherosclerosis and diabetic angiopathy.

Amino Acid Sequence↗