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Biomedical subjects

N Ueda

Publications and source records attributed to N Ueda.

At least 199 records · Page 11Linked to original sources
PubMed1996

Inhibition of TGF-beta 1 expression by antisense oligonucleotides suppressed extracellular matrix accumulation in experimental glomerulonephritis.

Overproduction of transforming growth factor-beta 1 (TGF-beta 1) has been implicated in the pathogenesis of fibrotic diseases. TGF-beta 1 plays a crucial role in the accumulation of extracellular matrix (ECM) in human and experimental glomerular diseases. However, it remains unclear whether inhibition of TGF-beta 1 overproduction would suppress TGF-beta 1-induced ECM accumulation. To inhibit the overproduction of TGF-beta 1 in experimental glomerulonephritis induced by anti-Thy 1.1 antibody, we introduced antisense oligodeoxynucleotides (ODN) for TGF-beta 1 into the nephritic kidney by the HVJ-liposome-mediated gene transfer method. Sense, scrambled or reverse ODN were also introduced as controls. Transfected ODN accumulated mainly in the nuclei of mesangial cells in the glomeruli of transfected kidneys. In the antisense ODN-transfected rats, a marked decrease in expression of TGF-beta 1 mRNA was confirmed by Northern analysis. Consequently, the expression of TGF-beta 1 protein in the glomerulus was markedly reduced in the antisense ODN-transfected kidney with a comparable effect in preventing glomerular ECM expansion in experimental glomerulonephritis. In contrast, sense, scrambled and reverse ODNs failed to suppress TGF-beta 1 expression and ECM accumulation. Thus, these results suggested that inhibition of TGF-beta 1 overproduction could suppress progression to glomerulosclerosis.

Animals↗
PubMed1996

Endonuclease induced DNA damage and cell death in chemical hypoxic injury to LLC-PK1 cells.

Hypoxia is considered to result in a necrotic form of cell injury. We examined the role of endonuclease activation, considered a feature of apoptosis, in DNA damage and cell death in hypoxic injury in LLC-PK1 cells. Hypoxia in LLC-PK1 cells was induced using a combination of glucose deprivation and a mitochondrial inhibitor, antimycin A (10 microM). Chemical hypoxia caused DNA damage as measured by the alkaline unwinding assay and internucleosomal DNA fragmentation that preceded cell death. Incubating protein extract of cells subjected to chemical hypoxia with calf thymus DNA resulted in oligonucleosome length fragments, which were prevented by an endonuclease inhibitor, aurintricarboxylic acid. Chemical hypoxia resulted in an increased DNA degrading activity with a molecular mass of approximately 15 kDa. Endonuclease inhibitors, aurintricarboxylic acid and Evans blue, prevented antimycin A-induced DNA strand breaks, fragmentation and cell death. We conclude that endonuclease activation plays an important role in chemical hypoxic injury to LLC-PK1 cells.

Animals↗
PubMed1996

Role of 'catalytic' iron in an animal model of minimal change nephrotic syndrome.

Treatment of minimal change disease, like most glomerulonephritides, is empirical because underlying mechanisms that cause glomerular injury are not known. We examined a pathogenic role of 'catalytic' iron in a model of minimal change nephrotic syndrome induced by injection of puromycin aminonucleoside (7.5 mg/100 g body wt) to rats. Although there was no significant change in non-heme iron content in glomeruli, the bleomycin-detectable iron (capable of catalyzing free radical reactions) was markedly increased in glomeruli from nephrotic rats when compared to control. In contrast, despite a marked and significant increase in the non-heme iron content in tubules, there was no significant change in the bleomycin-detectable iron in tubules from nephrotic rats. In a separate in vivo study, the iron chelator, deferoxamine, prevented the increase in the bleomycin-detectable iron in glomeruli and provided complete protection against proteinuria. Taken together, our data suggest an important pathogenetic role for glomerular catalytic iron in the puromycin aminonucleoside-induced minimal change nephrotic syndrome.

Animals↗
PubMed1996

Bilateral sensorineural hearing loss associated with the point mutation in mitochondrial genome.

Mitochondrial DNA (mtDNA) mutation associated with sensorineural hearing loss (SNHL) has previously been described in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and in aminoglycoside-induced deafness. The authors of this study report three cases of SNHL associated with mtDNA mutation (3243A-->G). They examined the clinical features of this type of SNHL by audiologic studies and examined the mtDNA mutation by the polymerase chain reaction technique. In the three cases described, the SNHL had an adult onset and was bilateral and symmetrical. All patients had adult-onset diabetes mellitus. Audiologic studies revealed that the SNHL in all patients derived from the cochlea rather than from retrocochlear sites. It is presumed that mtDNA mutation results in mitochondrial dysfunction in cochlear tissues (i.e., hair cells and stria vascularis) and in neurons of the auditory pathway. Genetic analysis of mtDNA offers new insight into the diagnosis and treatment of SNHL.

Adolescent↗
PubMed1996

Distribution of Ca2+ channels on cochlear outer hair cells revealed by fluorescent dihydropyridines.

Physiological evidence has shown that cochlear outer hair cells (OHC) possess L-type voltage-dependent Ca2+ channels through which Ca2+ enters the OHC during depolarization. Their subcellular distribution has, however, remained unclear. In this study, the distribution of L-type Ca2+ channels on the basolateral plasma membrane of OHC has been demonstrated by the use of a laser scanning confocal microscope (LSCM) and a fluorescent probe DMBODIPY-DHP. The fluorescent staining pattern on the basolateral wall is nonuniform, suggesting a heterogeneous distribution of the channels in the plasma membrane. Direct imaging of intracellular Ca2+ visualized in real time by means of the LSCM and the fluorescent Ca2+ probe fluo 3 revealed temporal and spatial integration of Ca2+ movements and Ca2+ channel distribution. Exposure to high-K+ solution induced heterogeneity in the subcellular increase in the intracellular Ca2+ concentration. These results suggest that the heterogeneous distribution of L-type Ca2+ channels on the basolateral membrane might induce heterogeneous intracellular Ca2+ distribution during electrical activity in the OHC.

Animals↗
PubMed1996

Diurnal heart rate variability in healthy subjects: effects of aging and sex difference.

To study the effects of aging and gender, circadian profiles of heart rate variability were evaluated for 105 healthy volunteers by frequency domain analysis of a Holter electrocardiogram record. The low-frequency (LF) component representing cardiac beta-adrenergic function showed high values for the 0800-1200 period in male subjects and the 1200-2400 period in female subjects. The high-frequency (HF) component representing parasympathetic function showed a peak for the 0000-0600 period in both male and female subjects independent of age. Male subjects showed significantly higher %LF [LF/(LF + HF) x 100] than female subjects. LF showed consistently highly significant correlation with age. These basic findings can help elucidate the diurnal profile of cardiac nerve function and how it is affected by aging and sex difference.

Adult↗
PubMed1996

Role of reactive oxygen metabolites in DNA damage and cell death in chemical hypoxic injury to LLC-PK1 cells.

Hypoxia is considered to result in a necrotic form of cell injury. We have recently demonstrated a role of endonuclease activation, generally considered a feature of apoptosis, to be almost entirely responsible for DNA damage in hypoxic injury to renal tubular epithelial cells. The role of reactive oxygen metabolites in endonuclease-induced DNA damage and cell death in chemical hypoxic injury has not been previously examined. LLC-PK1 cells exposed to chemical hypoxia with antimycin A resulted in enhanced generation of intracellular reactive oxygen species as measured by oxidation of a sensitive fluorescent probe, 2',7'-dichlorofluorescin diacetate. Superoxide dismutase, a scavenger of superoxide radical, significantly reduced the fluorescence induced by antimycin A and provided significant protection against chemical hypoxia-induced DNA strand breaks (as measured by the alkaline unwinding assay). Pyruvate, a scavenger of hydrogen peroxide, provided significant protection against chemical hypoxia-induced DNA strand breaks and DNA fragmentation (as measured by agarose gel electrophoresis). The interaction between superoxide anion and hydrogen peroxide in the presence of a metal catalyst leads to generation of other oxidant species such as hydroxyl radical. Hydroxyl radical scavengers, dimethylthiourea, salicylate, and sodium benzoate, and two metal chelators, deferoxamine and 1,10-phenanthroline, also provided marked protection against DNA strand breaks and DNA fragmentation. These scavengers of reactive oxygen metabolites and metal chelators provided significant protection against cell death as measured by trypan blue exclusion and lactate dehydrogenase release. Taken together, these data indicate that reactive oxygen species play an important role in the endonuclease activation and consequent DNA damage, as well as cell death in chemical hypoxic injury to renal tubular epithelial cells.

Animals↗
PubMed1996

Arachidonate 12-lipoxygenase in porcine anterior pituitary cells: its localization and possible function in gonadotrophs.

Arachidonate 12-lipoxygenase, which oxygenates positions 12 and 13 of arachidonic and linoleic acids, is present in porcine anterior pituitary cells. Colocalization of the 12-lipoxygenase with various pituitary hormones was examined by immunohistochemical double-staining using antibodies against 12-lipoxygenase and various anterior pituitary hormones. Under light microscopy, approximately 7% of the cells producing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were positive for 12-lipoxygenase, whereas the enzyme was detected in less than 2% of the cells producing thyrotrophin, prolactin, growth hormone (GH), and adrenocorticotrophin. In an attempt to examine the participation of 12-lipoxygenase metabolites in pituitary hormone release, we incubated the primary culture of porcine anterior pituitary cells with 12-hydroperoxy-arachidonic acid or 13-hydroperoxy-linoleic acid. Significant stimulation of LH and FSH release by these hydroperoxides was observed at 10 microM in a time-dependent manner. At doses around 10 microM these compounds produced responses of similar magnitude to 1 nM gonadotrophin-releasing hormone (GnRH), but higher concentrations (30 microM) of the compounds were required for GH release. In contrast, 12-hydroxy-arachidonic and 13-hydroxy-linoleic acids were almost ineffective. Furthermore, the gonadotrophin release by 1 nM GnRH was inhibited by nordihydroguaiaretic acid (a lipoxygenase inhibitor) with an IC50 of about 5 microM. Thus, the hydroperoxy (but not hydroxy) products of 12-lipoxygenase may be involved in the release of pituitary hormones especially LH and FSH.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1996

A low-affinity vasopressin V2-receptor gene in a kindred with X-linked nephrogenic diabetes insipidus.

In this study, a mutation in vasopressin Type 2 receptor (V2R) in a patient with hereditary nephrogenic diabetes insipidus (NDI) has been identified and characterized. The sequencing of the V2R gene from the patient revealed that there was a missense mutation (TAT to TGT) resulting in the substitution of 205Tyr for Cys in the putative third extracellular domain. The expression analysis in COS cells showed that the binding affinity of the mutant receptor (KD = 19.8 nM) for arginine vasopressin was much lower than that of the wild-type receptor (KD = 1.8 nM) so that intracellular cAMP production stimulated by arginine vasopressin was impaired in cells with the mutant V2R. From these results, it was concluded that the single amino-acid substitution of V2R is responsible for this familial disease.

Adult↗
PubMed1996

Kidney iron status in passive Heymann nephritis and the effect of an iron-deficient diet.

In the study presented here, the iron status in the kidney in passive Heymann nephritis, a complement-dependent model of membranous nephropathy, was examined. To examine whether the effect of immune injury on iron status has a pathogenic role, the effect of an iron-deficient diet was also determined. Injection of the anti-Fx1A antibody (10 mg/100 g body wt) in Sprague-Dawley rats resulted in no change in the serum iron level, a marked increase in the urinary excretion rate of iron, a marked increase in non-heme iron content of kidney cortex, and a marked increase in the non-heme iron level in tubules. These increases in iron were prevented by feeding the rats an iron-deficient diet. In the rats fed a normal iron diet and injected with anti-Fx1A-lgG, there was no significant change in the non-heme iron level in glomeruli. However, an iron-deficient diet resulted in a significant decrease in the non-heme iron level in glomeruli, compared with its respective control. In addition, an iron-deficient diet significantly reduced urinary protein excretion rate (Day 5: iron-replete, 68 +/- 12 mg/24 h, N = 12; iron-deficient, 36 +/- 11, N = 10, P < 0.05) in the complement-dependent immune phase of the glomerular injury. Taken together, these data indicate a marked alteration in the iron status in the kidney and suggest an important role of iron in glomerular injury of passive Heymann nephritis.

Animals↗
PubMed1996

Angiotensin I-converting enzyme insertion/deletion polymorphism: potential significance in nephrology.

Angiotensin I-converting enzyme (ACE) plays a pivotal role in cardiovascular homeostasis and by activating angiotensin I into angiotensin II and inactivating bradykinin. These two peptides play antagonistic roles on the cardiovascular system by regulating vascular tone and vascular smooth muscle cell proliferation. Identification of the ACE gene as a genetic marker for various forms of cardiovascular disease is a recent result of the progress made in molecular biology and genetics. The insertion/deletion (ID) polymorphism of the ACE gene defined by the presence or absence of the 287 base pair Alu sequence situated in intron 16 has been investigated as a possible genetic marker for a variety of cardiovascular disease including myocardial infarction, essential hypertension, cardiomyopathy, and diabetic vascular complications. This paper reviews prior reports and briefly describes our recent study on the association of the ACE I/D polymorphism and antiproteinuric effect of ACE inhibitors in patients with proteinuria.

Cardiovascular Diseases↗
PubMed1996

Role of protein phosphatase in malignant osteogenic and soft tissue tumors.

The expression of the three catalytic subunits of protein phosphatase (PP) type 1 and 2A, PP1 alpha, PP1 gamma 1, and PP2AC, was examined in osteogenic tumors and soft tissue tumors by immunohistochemical analysis. The percentage of cells stained positively with antiserum against PP1 catalytic subunit isoform PP1 gamma 1, was significantly higher in malignant osteogenic tumors (chondrosarcoma, osteosarcoma, and Ewing's sarcoma) and in malignant soft tissue tumors (liposarcoma and malignant fibrous histiocytoma [M.F.H.]) than in benign tumors (osteochondroma, osteoblastoma, ossifying fibroma, enchondroma and lipoma). Furthermore, the malignant tumor lesions showed a markedly high number of cells in the S-phase fraction of the cell cycle, as compared to benign tumors. These results suggest that PP1 gamma 1 is involved in the accelerated growth of malignant tumor cells.

Bone Neoplasms↗
PubMed1996

[Prostaglandin E1 at low-doses improved right ventricular ejection fraction in anesthetic management for CABG].

A 52-year-old male for CABG developed a severe right heart failure, because of the direct injury to the right ventricular wall, after cardiopulmonary bypass. The volume loading therapy could not improve the cardiac function, then we used an infusion of low-dose prostaglandin E1 (0.02-0.04 micrograms.kg-1.min-1) for the acute right heart failure with increased pulmonary vascular resistance. After continuous infusion of this dose, the pulmonary vascular resistance decreased quickly, the right ventricular ejection fraction increased, and the stroke volume index also improved. These hemodynamic changes are the result of the potent vasodilating effect of PGE1, that especially could decrease selectively the pulmonary vascular resistance, and increase the preload of the left ventricle. This dose of PGE1, did not cause a severe systemic hypertension that is a serious complication during vasodilating therapy with any vasoactive drugs. In the present case, we speculated that the low-dose PGE1, is effective to improve the right ventricular function during the acute right heart failure which resulted from the intrinsic right ventricular dysfunction.

Alprostadil↗