Biomedical subjects

Y Ihara

Publications and source records attributed to Y Ihara.

At least 163 records · Page 9Linked to original sources

PubMed1995

Changes of beta-1,4-N-acetylglucosaminyltransferase III (GnT-III) in patients with leukaemia.

Changes in the activity and transcription of UDP-N-acetylglucosamine: beta-D-mannoside beta-1,4-N-acetylglucosaminyl-transferase III (GnT-III: EC 2.4.1.144) were investigated in haematological malignancies. GnT-III activity was elevated in patients with chronic myelogeneous leukaemia in blast crisis (CML-BC) and patients with multiple myeloma (MM); whereas most of the normal healthy subjects and patients with other haematological malignancies, including CML in its chronic phase, showed negligible activity. The GnT-III transcript of leukaemic cells from various haematological diseases showed a single band with a similar size. The ratio of GnT-III activity per normalized transcript in CML-BC was considerably higher than in the other conditions, which provided the possibility that in CML-BC the transcript or the enzyme protein might be more stable, or that a post-translational modification of the enzyme might enhance its activity. Furthermore, a lectin blot analysis of patient specimens and a lectin fluorescence study of CML cell lines revealed that E4-PHA binding to surface glycoproteins correlated with GnT-III activity, indicating that more bisecting GlcNAc was added to these glycoproteins, catalysed by elevated GnT-III in CML-BC.

Blast Crisis↗

PubMed1995

Free radicals, lipid peroxides and antioxidants in blood of patients with myotonic dystrophy.

We studied the levels of free radicals, lipid peroxides and antioxidants, as well as superoxide dismutase (SOD) activity in the blood of six patients with myotonic dystrophy (MyD) (mean age 52.8, SD 5.0 years) and seven controls (mean age 48.8, SD 6.3 years). Electron spin resonance was used to assess the free radicals by the spin-trapping method using 5,5-dimethyl-1-pyrroline-1-oxide. The levels of C centre radical (P < 0.05) and H radical (P < 0.05) in blood from the six MyD patients were significantly higher than those in the seven controls. The SOD activities in red blood cells and serum from the six MyD patients showed no significant difference from those in the seven controls. The serum lipid peroxide concentration was increased in five of the MyD patients and tended to increase further as the disease progressed. The serum vitamin E level was low in two patients and in the low normal range in three. Serum coenzyme Q10 was decreased in four patients. The serum selenium level was decreased in two patients and that of serum albumin was decreased in three. Therefore we conclude that increased levels of free radicals and lipid peroxides and decreased antioxidant levels play an important role in the pathogenesis of MyD.

Antioxidants↗

PubMed1995

Superoxide dismutase and free radicals in sporadic amyotrophic lateral sclerosis: relationship to clinical data.

We studied the relationships between the superoxide dismutase (SOD) activity, free radical (FR) levels and clinical data in patients with sporadic amyotrophic lateral sclerosis (SALS). The SOD activities and blood FR levels of 16 patients with SALS (mean age 58.6 +/- 10.2 years), 11 with other neurological disease, including myotonic dystrophy (ND, mean age 53.5 +/- 9.1 years), and 15 normal control subjects (mean age 56.2 +/- 7.3 years) were measured. The mean levels of FR in blood from the patients with SALS and ND and the SOD activities in red blood cells (RBC) from those with ND were significantly higher than the corresponding control values. There was a positive correlation between the SOD activities in RBC and blood hydroxyl radical levels in the patients with ND, but neither the patients with SALS nor the controls showed such a correlation. The SALS patients without pyramidal signs showed slow disease progression and their mean RBC SOD activity was significantly higher than the corresponding control value. We compared the FR levels and SOD activities of 8 patients who needed a respirator within 40 months after the onset of SALS (SALS40, mean age 58.7 +/- 9.4 years), 3 who needed a respirator over 100 months after the onset of SALS (SALS100, mean age 58.3 +/- 15.9 years) and the controls. The mean blood FR levels of the SALS40 and SALS100 patients were significantly higher than the corresponding control values. The mean SOD activity in RBC from the SALS100 group was significantly higher than the SALS40 and control group values. Therefore, we concluded that elevated blood FR levels do not induce RBC SOD in SALS patients and that the disease progressed more rapidly in SALS patients with low than high RBS SOD activities.

Aged↗

PubMed1995

Cerebrospinal fluid corticotropin-releasing hormone in neurodegenerative diseases: reduction in spinocerebellar degeneration.

Levels of corticotropin-releasing hormone (CRH) in cerebrospinal fluid (CSF) were examined in patients with spinocerebellar degeneration (SCD) including olivopontocerebellar atrophy (OPCA), dentatorubropallidoluysian atrophy (DRPLA) and Friedreich's ataxia, Parkinson's disease (PD) and senile dementia of the Alzheimer type (SDAT), and normal aged subjects. CRH concentrations in CSF were significantly reduced in SCD compared to SDAT, PD and CSF and normal aged subjects. It is likely that degeneration not only of the cerebral cortex and the limbic system but also of the subcortical structures such as the brainstem and the cerebellum alters levels of CRH in CSF. Together with the recent anatomical and physiological evidence, the results suggest pathophysiological relevance of CRH for the cerebellar symptoms in SCD.

Adult↗

PubMed1995

Apolipoprotein E genotype, Alzheimer's pathologies and related gene expression in the aged population.

We have investigated the effect of genotypes of apolipoprotein E (ApoE) on the pathologies found in Alzheimer's disease (AD) and its related gene expression in 38 aged human brains obtained from consecutive autopsied cases. ApoE2/3, -3/3, -3/4, and -4/4 were typed in those aged brains, with ApoE3/3 being most prevalent. The AD pathologies were undetectable in ApoE2/3 brains, but were frequently observed in the other ApoE groups. In ApoE3/3 brains, 55%, 34%, and 24% of the cortical sections examined showed senile plaques (SPs), neurofibrillary tangles (NFTs), and cerebral amyloid angiopathy (CAA), respectively. In ApoE4/4 brains, the SP formation was significantly higher. The ApoE genotype neither affected ApoE, APP, or tau mRNA level, nor the differential expression of the latter two. These results suggest that ApoE4/4 accelerates and ApoE2/3 decelerates the development of the AD pathologies in the aged brain, but this is not through alterations of the APP and tau gene expression.

Aged↗

PubMed1995

Dominant and differential deposition of distinct beta-amyloid peptide species, A beta N3(pE), in senile plaques.

We analyzed an amino-terminal modification of beta-amyloid (A beta) peptide in brain, using anti-A beta antibodies that distinguish distinct molecular species. Examination of cortical sections from 28 aged individuals with a wide range in senile plaque density revealed that a molecular species distinct from the standard A beta is deposited in the brain in a dominant and differential manner. This modified A beta peptide (A beta N3(pE)) starts at the 3rd aminoterminal residue of the standard A beta, glutamate, converted to pyroglutamate through intramolecular dehydration. Because plaques composed of A beta N3(pE) are present in equivalent or greater densities than those composed of standard A beta bearing the first amino-terminal residue (A beta N1) and because deposition of the former species appears to precede deposition of the latter, as confirmed with specimens from Down's syndrome patients, the processes involved in A beta N3(pE) production and retention may play an early and critical role in senile plaque formation.

Adult↗

PubMed1995

GM1 ganglioside-bound amyloid beta-protein (A beta): a possible form of preamyloid in Alzheimer's disease.

The earliest event so far known that occurs in the brain affected with Alzheimer's disease (AD) is the deposition and fibril formation of amyloid beta-protein (A beta). A beta is cleaved from a glycosylated membrane protein, called beta-amyloid protein precursor, and normally secreted into the extracellular space. Here we report on the presence of membrane-bound A beta that tightly binds GM1 ganglioside. This suggests that this novel A beta species, rather than secreted A beta, may act as a 'seed' for amyloid and further that intracellular abnormalities in the membrane recycling already exist at the stage of amyloidogenesis.

Adult↗

PubMed1995

Relationship between lupus anticoagulant (LAC) and pregnancy-induced hypertension.

Lupus anticoagulant (LAC), a serum antiphospholipid autoantibody, is believed to be one of the causes of infertility or fetal loss. The purpose of the present study was to evaluate the role of LAC in the pathogenesis of hypertension during pregnancy. In this study, 20 pregnant women with hypertension were classified into two groups: 14 patients who did not have hypertension before the pregnancy but developed it during the pregnancy (pregnancy-induced hypertension; Group A) and 6 patients who had hypertensive or renal disease before the pregnancy, and developed further hypertension during the pregnancy (pregnancy-aggravated hypertension; Group B). A LAC coagulation assay was performed, and the presence of LAC in each group was compared. All 14 patients in group A were LAC-negative. In contrast, 3 of the 6 patients in group B were LAC-positive, and had clinical autoimmune diseases. The incidence of pregnancy-induced hypertension was also examined in 15 pregnancies from 9 LAC-positive women who had a history of repeated fetal loss but no systemic autoimmune disease (Group C). None of these 15 pregnancies had hypertensive complications, even when they reached term. In the placentas of LAC-positive women, no characteristic changes other than fibrinoid degeneration and microscopic infarction were observed upon histological examination. These results suggest that LAC does not relate with the onset of hypertension during pregnancy.

Adult↗

PubMed1995

Dephosphorylation of fetal-tau and paired helical filaments-tau by protein phosphatases 1 and 2A and calcineurin.

We have reported that many sites of tau in fetal brain (fetal-tau) as well as in paired helical filaments (PHF-tau) are phosphorylated. In the present study, we used site-specific antibodies and peptide mapping to examine protein phosphatases involved in dephosphorylation of fetal-tau and PHF-tau. Immunoblot analysis and electrophoretic mobility showed that protein phosphatases 1 and 2A and calcineurin could dephosphorylate fetal-tau and PHF-tau. Phosphoserines 199, 202, 396, and 413 and phosphothreonine 231, numbered according to the longest human tau isoform, were dephosphorylated, as shown by the immunoblot analysis. Phosphoserine 422 was dephosphorylated by protein phosphatase 2A and calcineurin, but not by protein phosphatase 1. Peptide mapping with Achromobacter lyticus protease 1 showed that phosphoserines 199, 202, 235, and 396 and phosphothreonine 231 were dephosphorylated by protein phosphatases. Fetal-tau was more rapidly dephosphorylated by protein phosphatase 2A and calcineurin than PHF-tau. Interestingly, PHF-tau which had not been solubilized with guanidine HCl was little dephosphorylated by protein phosphatases. Thus, PHF-tau in neurofibrillary tangles of Alzheimer's disease brain is likely to be resistant to dephosphorylation by protein phosphatases.

Amino Acid Sequence↗

PubMed1995

Molecular diversity and functional characterization of voltage-dependent calcium channels (CACN4) expressed in pancreatic beta-cells.

Dihydropyridine-sensitive voltage-dependent calcium channels (VDCC) play a crucial role in insulin secretion. We recently have cloned a human alpha 1-subunit of the VDCC expressed in pancreatic beta-cells, designated CACN4. In this study we have isolated complementary DNAs encoding two forms of rat CACN4 (rCACN4A and rCACN4B) from a rat insulinoma RINm5F complementary DNA library. Rat CACN4A is a protein of 2203 amino acids and is the rat homolog of human CACN4, whereas rCACN4B lacks 535 amino acids in the carboxyl-terminal region, probably due to alternative splicing. We have found two additional variations, one in the intracellular loop between repeats I and II and the other in the extracellular region between the third and fourth segments of repeat IV. Reverse transcriptase-polymerase chain reaction analysis of rat pancreatic islet messenger RNA reveals that these variants are present in pancreatic islets. In addition, whole-cell voltage-clamp recordings of Chinese hamster ovary cells stably expressing the alpha 1-subunit (rCACN4A or rCACN4B) with or without the calcium channel beta 2-subunit show that coexpression of rCACN4A with the beta 2-subunit or rCACN4B with the beta 2-subunit elicits L-type VDCC currents, whereas expression of the alpha 1-subunit alone does not, indicating that CACN4 can associate functionally with the beta 2-subunit and that the beta-subunit is essential for functional expression of CACN4. These results suggest that there are various subtypes of CACN4 expressed in pancreatic beta-cells, and that both rCACN4A and rCACN4B can function as VDCC. Furthermore, the present study suggests that the expression of the beta-subunit as well as the alpha 1-subunit may participate in the regulation of insulin secretion.

Amino Acid Sequence↗

PubMed1995

Gene expression of N-acetylglucosaminyltransferases III and V: a possible implication for liver regeneration.

N-acetylglucosaminyltransferases III and V (GnT-III and -V) are key enzymes in the synthesis of the branches of asparagine-linked oligosaccharides. Although their messenger RNAs (mRNAs) are expressed in various rat tissues, they are not detected in normal rat liver. Expression of the GnT-III and -V mRNAs, however, increased in regenerating liver after two-thirds partial hepatectomy compared with sham-operated rats. The enzymatic activities of GnT-III and -V increased in proportion to mRNA expression. To determine which type of cells in the liver have high activities of these glycosyltransferases, hepatocytes and nonparenchymal cells were separated by means of a two-step collagenase perfusion technique. GnT-III activity was only detected in nonparenchymal cells of normal rat liver. However, during liver regeneration, GnT-III activity increased and thus was also detectable in hepatocytes. GnT-V activity was detected in both types of cells. These data were supported by reverse transcription-polymerase chain reaction results. Although the mechanism underlying the induction of these glycosyltransferases is unknown, lectin blot analysis showed that oligosaccharides in many glycoproteins, including hepatocyte growth factor, a major growth factor associated with liver regeneration, were newly synthesized during liver regeneration. This is the first report on the expression of glycosyltransferases during liver regeneration and suggests that there are different mechanisms involved in regulation of the genes of GnT-III and -V during liver regeneration.

Animals↗

PubMed1995

Aquaretic effect of a potent, orally active, nonpeptide V2 antagonist in men.

Solute-free water diuretics (aquaretics) that antagonize hydrosmotic vasopressin 2 (V2) receptors may be useful in treating diseases in which water is retained. An orally active, nonpeptide, selective V2 antagonist (OPC-31260) was administered in six dose steps (3, 15, 30, 60, 100 and 200 mg) to six healthy, normally hydrated men to investigate the aquaretic effects in comparison with 12 placebo-treated control subjects (two at each dose). All subjects tolerated all six doses without serious clinical side effects. OPC-31260 increased the first 6-hr hypotonic urine volume dose-dependently. Administration at 30 mg raised the 6-hr urine volume to 2 times, 100 mg to 3 times and 200 mg to 4 times (1828.0 +/- 130.2 ml/6 hr) that of the placebo group (470.4 +/- 52.1 ml/6 hr). The drug increased urine flow maximally between 1 and 1.5 hr at all doses (e.g., 10.0 +/- 0.7-10.8 +/- 0.4 ml/min at 60-200 mg). The drug rapidly lowered urine osmolality for 4 hr, particularly between 60 and 90 min (e.g., 72.3 +/- 2.3 and 62.3 +/- 5.1 mOsm/kg at 100 and 200 mg, respectively). In marked hypotonic diuresis, mean free-water clearance of the 6-hr urine increased dose-proportionally into the positive range, reaching 2.82 +/- 0.21 ml/min at 200 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1995

[Axonal Guillain-Barré syndrome associated with anti-GalNAc-GD1a antibody subsequent to Campylobacter jejuni (PEN 43) enteritis].

We reported a 16-year-old boy who had Guillain-Barré syndrome (GBS) after suffering diarrhea. Campylobacter jejuni was isolated from his stool, and the serotype belonged to PEN 43. Neurologic examination revealed distal-dominant muscle weakness atrophy, and mild sensory disturbance. Motor and sensory nerve conduction velocities were normal, but compound muscle action potentials were markedly reduced. Serum from the patient had high titers of anti-FalNAc-GD1a antibodies. He had HLA-A24, B51, DRB1*04 and DRB1*09. His elder sister showed diarrhea and serum anti-C. jejuni antibody, but did not showed GBS and serum anti-ganglioside antibody. Her HLA types were A24, B51, DRB1*09 and DRB1*14.

Adolescent↗

PubMed1994

Multiple effector coupling of somatostatin receptor subtype SSTR1.

The signal transduction pathways of a cloned human somatostatin receptor subtype, SSTR1, have been investigated in CHO cells stably expressing this receptor. In SSTR1-expressing CHO cells, somatostatin-14 inhibits forskolin-stimulated cAMP formation in a dose-dependent manner with an ED50 of 1.0 x 10(-9) M. Somatostatin-14 also stimulates inositol 1,4,5-trisphosphate formation in a dose-dependent manner with an ED50 of 4.0 x 10(-8) M. Somatostatin-14 inhibitory action on adenylyl cyclase and stimulatory action on inositol 1,4,5-trisphosphate formation are both blocked by pertussis toxin, indicating that these effects of SSTR1 are mediated by pertussis toxin-sensitive G protein(s). Antiserum against Gi alpha 3 blocked the inhibitory effects of somatostatin-14 on forskolin-stimulated adenylyl cyclase, but antiserum against Gi alpha 1/Gi alpha 2 did not, indicating that Gi alpha 3 dominantly couples SSTR1 to adenylyl cyclase. These results demonstrate that SSTR1 can be coupled to different signaling pathways to exert multiple biological effects, one of which is mediated by Gi alpha 3.

Adenylyl Cyclases↗

PubMed1994

Expression of biologically active receptors for natriuretic peptides in the human uterus during pregnancy.

Human amnion cells secrete a large amount of brain natriuretic peptide (BNP). In the present study, to elucidate the possible roles of amniotic BNP during the course of human pregnancy, the tissue distributions of biologically active receptors of natriuretic peptides, atrial natriuretic peptide (ANP)-A receptor and ANP-B receptor in the human uterus during pregnancy were investigated by Northern blot analysis and an in vitro guanosine 3',5'-cyclic phosphate (cGMP) generation assay, the second messenger of natriuretic peptides, using crude membrane preparations. Both ANP-A and ANP-B receptor mRNAs were detected in the tissues of decidua vera, chorion laeve, myometrium and placenta. The in vitro cGMP generation assay revealed that the expression of ANP-A receptor was more prominent than that of ANP-B receptor in these tissues. On the other hand, in amniotic tissue only ANP-B receptor mRNA was weakly expressed but ANP-A receptor mRNA was not detected.

Atrial Natriuretic Factor↗

PubMed1994

Human somatostatin receptor, SSTR2, is coupled to adenylyl cyclase in the presence of Gi alpha 1 protein.

Somatostatin has been shown to exert diverse biological effects in various tissues. Recently, the human genes encoding five subtypes of somatostatin receptor (SSTR1-SSTR5) were cloned. Among these subtypes SSTR2 is present in many endocrine tumors as well as normal tissues and may mediate the effects of somatostatin analog, SMS201-995. In this study, we have investigated the intracellular effect of SSTR2 stably expressed in Chinese hamster ovary cells. Somatostatin-14 does not affect the forskolin stimulated cAMP formation when human SSTR2 is expressed in CHO cells, which lack internal Gi alpha 1 protein. However, somatostatin-14 inhibits the adenylyl cyclase in a dose dependent and pertussis toxin-sensitive manner when human SSTR2 is co-expressed with Gi alpha 1 in CHO cells. These results indicate that human SSTR2 is functionally coupled to Gi alpha 1 protein but not to Gi alpha 2 or Gi alpha 3 when expressed in CHO cells.

Adenylate Cyclase Toxin↗

PubMed1994

A cloned rat CD38-homologous protein and its expression in pancreatic islets.

Cyclic ADP-ribose recently has been suggested to be an important intracellular signal for insulin secretion. CD38, which was originally isolated from human lymphocytes as a surface marker, is active in the synthesis of cyclic ADP-ribose. We report here the cloning of a rat CD38-homologous protein (CD38H) which is expressed in pancreatic islets. The deduced amino acid sequence shows that rat CD38H is a protein of 303 amino acids (M(r), 34.4 kD) and contains one possible membrane-spanning domain, consistent with a type II transmembrane glycoprotein. The overall identity and similarity of the amino acid sequences between the human CD38 and the rat CD38H are 58% and 76%, respectively. RNA blot analysis showed a strong signal of 3.4 kb in rat brain, duodenum, and heart. CD38H also is shown to be expressed in pancreatic islets by the RT-PCR procedure, but its expression is not significantly different in Wistar and GK rats, a genetic model of non-insulin-dependent diabetes mellitus. The presence of rat CD38H in the pancreatic islets suggests that CD38H may be involved in insulin secretion by synthesizing cADP-ribose.

ADP-ribosyl Cyclase↗

PubMed1994

Spatial resolution of the primary beta-amyloidogenic process induced in postischemic hippocampus.

Proteolytic modifications of amyloid precursor protein (APP) play key roles in the development of Alzheimer's disease. However, each specific in vivo process has not yet been fully resolved in spatial terms because the orthodox approach employing electrophoretic analysis requires homogenization of samples and thus provides limited information on the localization of the process. To acquire such spatial information for the primary process involved in beta-amyloidogenesis, we have designed and developed a novel antibody exclusively specific to APP fragments possessing the exact amino terminus of the major beta-amyloid (A beta) peptide. Use of this antibody revealed that cleavage of APP at the amino terminal position of the A beta sequence is a normal steady-state process in gerbil hippocampus. Furthermore, nonfatal transient (10 min) forebrain ischemia followed by reperfusion enhanced the initial beta-amyloidogenic reaction mainly in pyramidal cells of CA1 sector and of dentate gyrus prior to and along with delayed neuronal degeneration. The APP fragments accumulated in cell bodies and dendrites of the neurons. These results suggest that beta-amyloidogenesis may involve a process that is also activated in postischemic brain and that ischemia-like conditions may contribute to pathogenic A beta accumulation.

Alzheimer Disease↗