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R Nagai

Publications and source records attributed to R Nagai.

At least 73 records · Page 4Linked to original sources
PubMed2001

Tbx5 associates with Nkx2-5 and synergistically promotes cardiomyocyte differentiation.

The cardiac homeobox protein Nkx2-5 is essential in cardiac development, and mutations in Csx (which encodes Nkx2-5) cause various congenital heart diseases. Using the yeast two-hybrid system with Nkx2-5 as the 'bait', we isolated the T-box-containing transcription factor Tbx5; mutations in TBX5 cause heart and limb malformations in Holt-Oram syndrome (HOS). Co-transfection of Nkx2-5 and Tbx5 into COS-7 cells showed that they also associate with each other in mammalian cells. Glutathione S-transferase (GST) 'pull-down' assays indicated that the N-terminal domain and N-terminal part of the T-box of Tbx5 and the homeodomain of Nkx2-5 were necessary for their interaction. Tbx5 and Nkx2-5 directly bound to the promoter of the gene for cardiac-specific natriuretic peptide precursor type A (Nppa) in tandem, and both transcription factors showed synergistic activation. Deletion analysis showed that both the N-terminal domain and T-box of Tbx5 were important for this transactivation. A G80R mutation of Tbx5, which causes substantial cardiac defects with minor skeletal abnormalities in HOS, did not activate Nppa or show synergistic activation, whereas R237Q, which causes upper-limb malformations without cardiac abnormalities, activated the Nppa promoter to a similar extent to that of wildtype Tbx5. P19CL6 cell lines overexpressing wildtype Tbx5 started to beat earlier and expressed cardiac-specific genes more abundantly than did parental P19CL6 cells, whereas cell lines expressing the G80R mutant did not differentiate into beating cardiomyocytes. These results indicate that two different types of cardiac transcription factors synergistically induce cardiac development.

Atrial Natriuretic Factor↗
PubMed2001

The fat-derived hormone adiponectin reverses insulin resistance associated with both lipoatrophy and obesity.

Adiponectin is an adipocyte-derived hormone. Recent genome-wide scans have mapped a susceptibility locus for type 2 diabetes and metabolic syndrome to chromosome 3q27, where the gene encoding adiponectin is located. Here we show that decreased expression of adiponectin correlates with insulin resistance in mouse models of altered insulin sensitivity. Adiponectin decreases insulin resistance by decreasing triglyceride content in muscle and liver in obese mice. This effect results from increased expression of molecules involved in both fatty-acid combustion and energy dissipation in muscle. Moreover, insulin resistance in lipoatrophic mice was completely reversed by the combination of physiological doses of adiponectin and leptin, but only partially by either adiponectin or leptin alone. We conclude that decreased adiponectin is implicated in the development of insulin resistance in mouse models of both obesity and lipoatrophy. These data also indicate that the replenishment of adiponectin might provide a novel treatment modality for insulin resistance and type 2 diabetes.

Adiponectin↗
PubMed2001

Immunohistochemical distribution and quantitative biochemical detection of advanced glycation end products in fetal to adult rats and in rats with streptozotocin-induced diabetes.

SUMMARY: We used immunohistochemical methods and four monoclonal antibodies for specific molecular structures of advanced glycation end products (AGE)-6D12, KNH-30, 1F6, and 2A2-to examine localization of AGE in fetal, young, and adult rats, and rats with streptozotocin-induced diabetes. 6D12 recognized N(epsilon)-(carboxymethyl)lysine (CML); KNH-30, N(epsilon)-(carboxyethyl)lysine (CEL); and 1F6, fluorolink. The epitope of 2A2 is as yet unknown. Immunoreactivities for these monoclonal antibodies were found in various organs and tissues in postnatal and adult rats, and accumulation increased with aging. In the fetuses, AGE structures were detected at 10 fetal days, and their accumulation increased during ontogeny. Reversed-phase high-performance liquid chromatography revealed CML in fetuses at 13 fetal days and in lungs of 28-week-old rats. In various organs and tissues of fetal, young, and adult rats, CML, CEL, 2A2-positive AGE, and fluorolink accumulated, in that order, which suggests that the accumulation of CML, a nonfluorescent/noncross-linked AGE, occurs earlier than accumulation of fluorolink, a fluorescent/cross-linked AGE. In diabetic rats, hepatocytes, splenic macrophages, renal glomerular endothelial and mesangial cells, testicular Leydig cells, and erythrocytes showed excessive accumulation of AGE, leading to the pathologic changes characteristic of diabetes mellitus. For the induction of these changes, persistent hyperglycemia and hyperketonemia might be important for acceleration of intracellular AGE accumulation in diabetic rats. Thus, AGE accumulation in tissues and cells occurs not only during aging and in diabetes mellitus but also from an early stage of ontogeny.

Aging↗
PubMed2001

G649, an allelic variant of the human H2 receptor with low basal activity, is resistant to upregulation upon antagonist exposure.

Orange et al reported an allelic variant of the human histamine H2 receptor, in which adenine 649 was replaced with guanine, to be more frequent in the schizophrenic population than controls in British Caucasians. The A649 to G change causes an Asn to Asp transition at amino acid position 217 in the third intracellular region, which is postulated to be important for receptor function. Herein, we analyzed the functional significance of this variant using wild-type and variant receptors expressed in Chinese hamster ovary cells. The variant receptor was associated with markedly lower basal cAMP productions than the wild-type receptor. Histamine-dependent cAMP productions via the variant receptor were lower as well. Treatment of cells expressing variant receptors with 10(-5) M ranitidine for 24 h resulted in a reduced degree of receptor upregulation as compared with the wild-type receptor. Thus, this is the first report of an allelic variant of the human H2 receptor which confers altered receptor function. To analyze gastric acid secretion in individuals with this variant, we examined 100 Japanese control subjects. However, neither heterozygotes nor homozygotes were found, suggesting that this variant, if present, is uncommon in the Japanese population.

Alleles↗
PubMed2001

Formation of advanced glycation end-product-modified superoxide dismutase-1 (SOD1) is one of the mechanisms responsible for inclusions common to familial amyotrophic lateral sclerosis patients with SOD1 gene mutation, and transgenic mice expressing human SOD1 gene mutation.

Neuronal Lewy body-like hyaline inclusions (LBHI) and astrocytic hyaline inclusions (Ast-HI) are morphological hallmarks of certain familial amyotrophic lateral sclerosis (FALS) patients with superoxide dismutase-1 (SOD1) gene mutations, and transgenic mice expressing the human SOD1 gene mutation. The ultrastructure of inclusions in both diseases is identical: the essential common constituents are granule-coated fibrils approximately 15-25nm in diameter and granular materials. Detailed immunohistochemical analyses have shown that the essential common protein of the inclusions in both diseases is an SOD1 protein. This finding, together with the immunoelectron microscopy finding that the abnormal granule-coated fibrils comprising the inclusions are positive for SOD1, indicates that these granule-coated fibrils containing SOD1 are important evidence for mutant SOD1-linked disease in human and mouse. For immunoelectron microscopy, the granule-coated fibrils are modified by advanced glycation endproducts (AGE) such as N(epsilon)-carboxymethyl lysine, pyrraline and pentosidine (Maillard reaction). Based on the fact that AGE themselves are insoluble molecules with direct cytotoxic effects, the granule-coated fibrils and granular materials are not digested by the lysosomal and ubiquitin systems. The neurons and astrocytes of the normal individuals and non-transgenic mice show no significant immunoreactivity for AGE. Considered with the mutant-SOD1 aggregation toxicity, a portion of the SOD1 comprising both types of the inclusion is modified by the AGE, and the formation of the AGE-modified SOD1 (probably AGE-modified mutant SOD1) is one of the mechanisms responsible for the aggregation (i.e. granule-coated fibril formation).

Amyotrophic Lateral Sclerosis↗
PubMed2001

Indomethacin induced bulky lymphadenopathy and eosinophilic pneumonia.

Indomethacin is one of the most popular non-steroidal anti-inflammatory drugs (NSAID). Although NSAID occasionally provoke bronchospasm and hypersensitivity pneumonia, they seldom cause lymphadenopathy. This is the first report in which NSAID induced both eosinophilic pneumonia and bulky intrathoracic lymphadenopathy simultaneously. A 76-year-old Japanese man experienced high fever and dyspnoea after using an indomethacin suppository. Computed tomography scan of his chest revealed massive mediastinal and hilar lymphadenopathy along with diffuse infiltration in both lungs. He was diagnosed to have eosinophilic pneumonia because of eosinophilia in his peripheral blood and bronchoalveolar lavage fluid (BALF). Without using glucocorticoids, the pulmonary infiltration and lymphadenopathy subsided spontaneously. As the blastoid transformation test using the lymphocytes in his BALF was positive to indomethacin, we judged that both his eosinophilic pneumonia and mediastinal lymphadenopathy were due to a hypersensitivity reaction to indomethacin. An allergic reaction to NSAID should be considered as a rare cause of mediastinal lymphadenopathy.

Aged↗
PubMed2001

Oozing from the pericardium as an etiology of cardiac tamponade associated with screw-in atrial leads.

Screw-in atrial pacing leads are widely used. Cardiac tamponade is a complication. An 81-year-old woman with advanced atrioventricular block underwent permanent pacemaker implantation and subsequently developed cardiac tamponade. At surgery, the lead-tip screw was found penetrated through the right atrium but not through the pericardium. The source of bleeding was confirmed to scratching the inner pericardial membrane by the screw tip. Although cardiac tamponade due to perforation and leakage is known, tamponade caused by the trauma of an atrial screw on the pericardium with resultant ooze is less well described.

Aged↗
PubMed2001

Different effects of angiotensin II and catecholamine on renal cell apoptosis and proliferation in rats.

BACKGROUND: We have recently found that chronic infusion of angiotensin II (Ang II) into rats resulted in an impairment of renal function, whereas norepinephrine (NE) infusion did not. We investigated whether chronic infusion of Ang II and NE caused different degrees of renal cell apoptosis and proliferation. METHODS: Rats were made hypertensive via continuous infusion of either Ang II or NE for up to seven days. Renal cell apoptosis and proliferation were analyzed by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) technique and staining with antibody against proliferating cell nuclear antigen (PCNA), respectively. In some experiments, an inducer or inhibitor of heme oxygenase-1 (HO-1) was administered to investigate the possible role of HO-1 in renal cell homeostasis. RESULTS: Infusion of Ang II, but not NE, resulted in approximately a sevenfold increase in bax protein at seven days of infusion. The TUNEL assay revealed that Ang II infusion significantly increased the number of apoptotic cells, whereas NE infusion did not. TUNEL- and PCNA-positive cells were mainly seen in the tubulointerstitial region of Ang II-infused rats. Ang II induced increased positivity of TUNEL, and PCNA was blocked completely by losartan, but only partially by hydralazine. Induction of HO-1 reduced and inhibition of HO increased Ang II-induced cell proliferation. CONCLUSIONS: These data suggest that Ang II plays a pivotal role in the development of renal cell proliferation and apoptosis in the setting of hypertension. The renal HO system may modulate proliferative and pro-apoptotic effects of Ang II.

Angiotensin II↗
PubMed2001

Glycoxidation-modified macrophages and lipid peroxidation products are associated with the progression of human diabetic nephropathy.

The aim of this study is to investigate the role of glomerular macrophages activated by glycoxidation and lipid peroxidation products in the progression of glomerular lesions in diabetic nephropathy. Renal biopsy samples from 43 patients with diabetes (age, 54 +/- 14 years) and 10 control cases were immunohistochemically examined for the expression of carboxymethyllysine (CML), a representative glycoxidative product; oxidized phosphatidylcholine (Ox-PC), a representative lipid peroxidation product; leukocyte common antigen (LCA); CD68; and macrophage scavenger receptor (MSR) class A. The severity of the diffuse lesions in each glomerulus was histologically graded from 0 to IV. When grade II and III lesions had Kimmelstiel-Wilson (KW) nodules, they were placed in a new category called grade III with KW nodules. The number of cells positive for CML, Ox-PC, LCA, CD68, and MSR was compared in different grades. The number of macrophages per glomerulus increased with the glomerular lesion grade and was highest in grade III with KW nodules. Conversely, the number of lymphocytes did not parallel the grade of glomerular lesions. Almost 50% of macrophages contained CML, and more than 40% of those were observed in exudative lesions, tuft adhesions, and at the periphery of KW nodules. Ox-PC accumulated in 50% of CML-positive macrophages, which coexpress MSR. Macrophages positive for CML and Ox-PC increased with the grade. Glomerular macrophages may be activated by glycoxidative and lipid peroxidation products through MSR and may have a role in the development of human diabetic glomerulosclerosis.

Adolescent↗
PubMed2001

Endogenous PPAR gamma mediates anti-inflammatory activity in murine ischemia-reperfusion injury.

BACKGROUND & AIMS: Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor whose activation has been linked to several physiologic pathways including those related to the regulation of intestinal inflammation. We sought to determine whether PPAR gamma could function as an endogenous anti-inflammatory pathway in a murine model of intestinal ischemia-reperfusion (I/R) injury. METHODS: PPAR gamma-deficient and wild-type mice were examined for their response to I/R procedure. Treatment with a PPAR gamma-specific ligand was also performed. RESULTS: In a murine model of intestinal I/R injury, we observed more severe injury in PPAR gamma-deficient mice and protection against local and remote tissue injury in mice treated with a PPAR gamma-activating ligand, BRL-49653. Activation of PPAR gamma resulted in down-regulation of intercellular adhesion molecule 1 expression by intestinal endothelium and tissue tumor necrosis factor alpha messenger RNA levels most likely by inhibition of the NF-kappa B pathway. CONCLUSIONS: These data strongly suggest that an endogenous PPAR gamma pathway exists in tissues that may be amenable to therapeutic manipulation in I/R-related injuries.

Animals↗
PubMed2001

Serum levels of myoglobin, creatine phosphokinase, and smooth muscle heavy-chain myosin in patients with ectopic pregnancy.

STUDY OBJECTIVE: Serum markers of smooth muscle destruction have been shown to be elevated in ectopic pregnancy, but they remain of questionable clinical utility. Our goal was to determine the clinical utility of 3 markers of smooth muscle destruction: creatine phosphokinase (CPK), smooth muscle heavy-chain myosin (SMHC), and myoglobin. METHODS: This was a prospective cohort study, with consecutive enrollment of all women in the first trimester of pregnancy who presented to our urban emergency department with complaints of lower abdominal pain, vaginal bleeding, or both. Patients were excluded from the study if there was a history of recent surgery or major trauma. Data analysis included receiver operating characteristic (ROC) curve, 95% confidence intervals (CIs), and a regression model. RESULTS: A total of 378 patients were enrolled, with 61 patients diagnosed with an ectopic pregnancy, and 317 patients placed in the non-ectopic pregnancy group with other diagnoses. ROC curve analysis revealed an area under the curve of 0.56 (95% CI 0.51 to 0.61) for CPK, 0.63 (95% CI 0.59 to 0.68) for SMHC, and 0.58 (95% CI 0.53 to 0.63) for myoglobin. A regression model analyzing the effects of race, maternal age, estimated gestational age, and serum levels of human chorionic gonadotropin beta-subunit found no significant confounders. CONCLUSION: Although there is a statistically significant elevation in the serum levels of SMHC, the range of values seen is too large to allow SMHC to be a useful screening tool.

Adult↗
PubMed2001

Advanced glycation end products in Descemet's membrane and their effect on corneal endothelial cell.

PURPOSE: [corrected] The purpose of this study was to evaluate the effect of advanced glycation end products (AGEs) in Descemet's membrane on the attachment and spreading of the corneal endothelial cells. METHODS: An anti-AGEs monoclonal antibody (6D12), which recognizes a N(epsilon)-carboxymethyl lysine (CML)-protein adduct as an epitope, was used for immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). Fresh bovine Descemet's membrane was incubated for 4 weeks in the buffered solution with 500 mM of glucose-6-phosphate (G-6-P). In the incubated Descemet's membrane, the immunohistochemical localization of CML was examined. Type I collagen-, type IV collagen-, fibronectin-, or laminin-coated 96-well plates were glycated by G-6-P. The amount of CML was determined by ELISA using 6D12. Cultured bovine corneal endothelial cells were seeded onto glycated or non-glycated extracellular matrix (ECM) in 96-well plates and allowed to attach for 3 hours. The number and the surface area of the attached cells were examined. RESULTS: Immunoreactivity to CML was detected in Descemet's membrane incubated in the buffered solution containing G-6-P. Glycation of fibronectin and laminin decreased the number and the surface area of the attached corneal endothelial cells. Aminoguanidine in the incubation mixture inhibited CML formation of ECM components and increased the number and the surface area of the attached corneal endothelial cells in a dose-dependent manner. CONCLUSIONS: AGE formation on fibronectin and laminin attenuated the attachment and spreading of the corneal endothelial cells. AGEs' formation in Descemet's membrane may be responsible for the corneal endothelial cell loss with aging and corneal endothelial abnormalities in diabetic patients

Animals↗
PubMed2001

Pulmonary intravascular lymphoma complicated with Pneumocystis carinii pneumonia: a case report.

We report a case of intravascular lymphoma (IVL) complicated with Pneumocystis carinii pneumonia (PCP). A 65-year-old male complaining of dyspnea and dementia was diagnosed to have pulmonary IVL by transbronchial lung biopsy. Concomitantly, deoxyribonucleic acid sequence specific to Pneumocystis carinii was detected in bronchoalveolar lavage fluid by polymerase chain reaction. Differential responses to the sequential treatments for PCP and IVL implied that increased serum lactate dehydrogenase (LDH) was due to PCP, whereas hypoxemia and dementia were due to IVL. Although pulmonary IVL and PCP share many clinical presentations, exact diagnosis is essential for their successful treatment.

Aged↗
PubMed2001

Evidence for the physiological and pathological roles of adrenomedullin from genetic engineering in mice.

Adrenomedullin (AM) has been implicated as having hypotensive as well as protective effects on organs and vessels against different kinds of injuries. To elucidate the in vivo pathophysiological roles of adrenomedullin, we established transgenic mice (AMTg) overexpressing adrenomedullin driven by preproendothelin-1 promoter and adrenomedullin knockout mice (AMKO). Blood pressure in AMTg was significantly lower than that in wild-type mice, and AMTg was significantly resistant to lipopolysaccharide-induced septic shock and vascular injuries. On the other hand, heterozygotes of AMKO, AM(+/-), were fully viable and hypertensive as compared with wild littermates. Mice homozygous for adrenomedullin null mutation (AM-/-) were embryonic lethal, and no embryos could survive beyond the midterm of gestation. Collectively, our findings indicate the indispensable role of adrenomedullin in circulatory homeostasis and the organ protection as well as the fetal morphogenesis and the maintenance of pregnancy.

Adrenomedullin↗