Biomedical subjects

M Teranishi

Publications and source records attributed to M Teranishi.

At least 19 recordsLinked to original sources

PubMed2006

Blood flow to the promontory in cochlear otosclerosis.

OBJECTIVE: To investigate Schwartze sign with measurements of blood flow to the promontory in patients with cochlear otosclerosis. DESIGN: Prospective clinical study. SETTING: Tertiary referral centre. PARTICIPANTS: Five patients with cochlear otosclerosis and five control subjects. Significant decalcification around the cochlea was observed by computed tomography (CT) in patients with cochlear otosclerosis. However, no recognizable lesion was observed at the oval window in two patients. One patient had mixed hearing loss and four patients had sensorineural hearing loss without an air-bone gap. MAIN OUTCOME MEASURES: The relationship between CT findings and the presence or absence of Schwartze sign was investigated. Blood flow to the promontory was measured through the tympanic membrane using laser speckle flowgraphy and laser Doppler flowmetry. RESULTS: The Schwartze sign correlated significantly with otosclerotic lesions invading the promontory. Patients with otosclerosis exhibited elevated and pulsating blood flow to the promontory with the Schwartze sign. CONCLUSIONS: Computed tomography demonstrated that cochlear otosclerosis can exist without the oval window lesion. Schwartze sign can be used as a sign of the otosclerotic invasion to the promontory. The reddening of the Schwartze sign is likely due to increased blood flow.

Adult↗

PubMed2003

A gene for a Class II DNA photolyase from Oryza sativa: cloning of the cDNA by dilution-amplification.

Ultraviolet radiation induces the formation of two classes of photoproducts in DNA-the cyclobutane pyrimidine dimer (CPD) and the pyrimidine [6-4] pyrimidone photoproduct (6-4 product). Many organisms produce enzymes, termed photolyases, which specifically bind to these lesions and split them via a UV-A/blue light-dependent mechanism, thereby reversing the damage. These photolyases are specific for either CPDs or 6-4 products. Two classes of photolyases (class I and class II) repair CPDs. A gene that encodes a protein with class II CPD photolyase activity in vitro has been cloned from several plants including Arabidopsis thaliana, Cucumis sativus and Chlamydomonas reinhardtii. We report here the isolation of a homolog of this gene from rice (Oryza sativa), which was cloned on the basis of sequence similarity and PCR-based dilution-amplification. The cDNA comprises a very GC-rich (75%) 5; region, while the 3; portion has a GC content of 50%. This gene encodes a protein with CPD photolyase activity when expressed in E. coli. The CPD photolyase gene encodes at least two types of mRNA, formed by alternative splicing of exon 5. One of the mRNAs encodes an ORF for 506 amino acid residues, while the other is predicted to code for 364 amino acid residues. The two RNAs occur in about equal amounts in O. sativa cells.

Amino Acid Sequence↗

PubMed2002

Positive association of CYP11B2 gene polymorphism with genetic predisposition to essential hypertension.

Predispositions to essential hypertension and cardiovascular diseases are possibly associated with gene polymorphisms of the renin-angiotensin system. Gene polymorphisms of angiotensinogen and angiotensin-converting enzyme genes have been suggested to be risk factors for hypertension and myocardial infarction. Concerning the polymorphism of aldosterone synthase (CYP11B2) gene, earlier studies have shown inconsistent results in terms of its relation to hypertension. In the present case-control study, we investigated the association of -344T/C polymorphism in the promoter region of human CYP11B2 gene with genetic predisposition to hypertension. The genotype of -344T/C polymorphism was determined in essential hypertension subjects (n=250) and normotensive subjects (n=221). The distributions of three genotypes (TT, TC, and CC) were significantly different between the hypertensive and the normotensive groups (chi(2)=9.61, P=0.008). Namely, the frequency of C allele was higher in the hypertensive patients than in the normotensive subjects (34.2 vs 26.5%, P=0.010). Our data suggest that the -344C allele of CYP11B2 gene polymorphism is associated with the genetic predisposition to develop essential hypertension.

Adult↗

PubMed2002

Z and W chromosomes of chickens: studies on their gene functions in sex determination and sex differentiation.

Since the discovery of SRY/SRY as a testis-determining gene on the mammalian Y chromosome in 1990, extensive studies have been carried out on the immediate target of SRY/SRY and genes functioning in the course of testis development. Comparative studies in non-mammalian vertebrates including birds have failed to find a gene equivalent to SRY/SRY, whereas they have suggested that most of the downstream factors found in mammals including SOX9 are also involved in the process of gonadal differentiation. Although a gene whose function is to trigger the cascade of gene expression toward gonadal differentiation has not been identified yet on either W or Z chromosomes of birds, a few interesting genes have been found recently on the sex chromosomes of chickens and their possible roles in sex determination or sex differentiation are being investigated. It is the purpose of this review to summarize the present knowledge of these sex chromosome-linked genes in chickens and to give perspectives and point out questions concerning the mechanisms of avian sex determination.

Animals↗

PubMed2001

Selective synthesis of 4-methoxyestrogen from 4-hydroxyestrogen.

The introduction of an oxygen atom into the C-6 position of 4-hydroxyestrogen allowed for the selective methylation of the two phenolic hydroxyl groups. When the 6-oxo derivative of 4-hydroxyestrone was benzylated in ethanol, only the 3-monobenzyl ether was obtained without formation of the 4-monobenzyl ether. Moreover, the 6-carbonyl group was further reduced to methylene almost quantitatively in the reaction of 4-acetoxy-6-oxoestrone 3-benzyl ether derivative with sodium borohydride. Therefore, 4-methoxyestrogen was synthesized by essentially combining these two reactions.

Estradiol↗

PubMed2001

Effects of alpha-tocopherol on cisplatin-induced ototoxicity in guinea pigs.

Cisplatin (CDDP), an antitumor agent widely used in the treatment of head and neck cancers, has dose-limiting side effects such as ototoxicity and nephrotoxicity. Recently, evidence has been accumulated to demonstrate that these side effects are closely related to oxidative stress. In the present study, we attempted to suppress CDDP-induced ototoxicity and nephrotoxicity in guinea pigs by administering alpha-tocopherol, a naturally occurring antioxidant. Hartley albino guinea pigs (250 approximately 300 g) were treated with CDDP (4 mg/kg intraperitoneally (I.P.)) for 3 days in the presence and absence of alpha-tocopherol (50 mg/kg I.P.) injection for 6 days. The combined treatment of animals with alpha-tocopherol distinctly improved the CDDP-induced side effects. These were: loss of Preyer's reflex at high frequencies; distinct elevation of auditory brain stem response threshold at 16 kHz; increased lipid peroxidation in the cochlea determined by the malondialdehyde-thiobarbituric acid method; substantial losses of outer hair cells in the basal and second turns of the cochlea; fragmentation of nuclear DNA detected by the TUNEL method in cochlear hair cells and cells in the stria vascularis; and increases in serum BUN and Cr. These results strongly suggest that alpha-tocopherol suppresses CDDP-induced ototoxicity and nephrotoxicity via the suppression of the increased production of reactive oxygen species.

Animals↗

PubMed2001

Transcripts of the MHM region on the chicken Z chromosome accumulate as non-coding RNA in the nucleus of female cells adjacent to the DMRT1 locus.

The male hypermethylated (MHM) region, located near the middle of the short arm of the Z chromosome of chickens, consists of approximately 210 tandem repeats of a BamHI 2.2-kb sequence unit. Cytosines of the CpG dinucleotides of this region are extensively methylated on the two Z chromosomes in the male but much less methylated on the single Z chromosome in the female. The state of methylation of the MHM region is established after fertilization by about the 1-day embryonic stage. The MHM region is transcribed only in the female from the particular strand into heterogeneous, high molecular-mass, non-coding RNA, which is accumulated at the site of transcription, adjacent to the DMRT1 locus, in the nucleus. The transcriptional silence of the MHM region in the male is most likely caused by the CpG methylation, since treatment of the male embryonic fibroblasts with 5-azacytidine results in hypo-methylation and active transcription of this region. In ZZW triploid chickens, MHM regions are hypomethylated and transcribed on the two Z chromosomes, whereas MHM regions are hypermethylated and transcriptionally inactive on the three Z chromosomes in ZZZ triploid chickens, suggesting a possible role of the W chromosome on the state of the MHM region.

Animals↗

PubMed2001

Absence of Z-chromosome inactivation for five genes in male chickens.

In order to examine if Z-chromosome inactivation, which is analogous to X-chromosome inactivation in mammals, takes place in male birds having ZZ sex chromosomes, five Z-linked genes of chickens which are expressed in both sexes in certain tissues were selected: i.e. genes for growth hormone receptor, nicotinic acetylcholine receptor beta3, aldolase B, beta1,4-galactosyltransferase I, and iron-responsive element-binding protein (also known as cytosolic aconitase). Antisense or sense riboprobe was prepared from an intronic sequence of each gene and subjected to fluorescence in situ hybridization to nascent transcripts of each gene in a nucleus. Each antisense riboprobe hyridized to two spots of nascent RNA which corresponded to its gene loci on the two Z chromosomes in a majority of nuclei in a tissue of the male. The efficiency of detection of two spots per nucleus was comparable to that for the glyceraldehyde-3-phosphate dehydrogenase gene, an autosomal housekeeping gene. These results suggest strongly that Z-chromosome inactivation, i.e. virtual silence of transcription at one of the alleles, does not take place for these five Z-linked genes in male chickens.

Animals↗

PubMed2001

Molecular forms of plasma and urinary adrenomedullin in normal, essential hypertension and chronic renal failure.

OBJECTIVES: Human adrenomedullin precursor is converted to glycine-extended adrenomedullin (AM-Gly), an intermediate inactive form of adrenomedullin. Subsequently, AM-Gly is converted to active form of mature adrenomedullin (AM-m). The aim of the present study was to investigate (i) whether sex or age influences plasma and urinary AM-m and AM-Gly levels in normal subjects; (ii) the daytime variability of plasma AM-m and AM-Gly levels in normal subjects; (iii) AM-m and AM-Gly levels and its ratio in plasma and urine in normal subjects, individuals with essential hypertension (HT), and chronic renal failure (CRF); and (iv) the ratio of AM-m and AM-total (T) in plasma of various veins and aorta. METHODS: We measured plasma levels and urinary excretions of AM-m, AM-Gly and AM-T (AM-m + AM-Gly) by recently developed immunoradiometric assay in normal subjects (n = 81), HT (n = 28) and CRF (n = 30). We also determined the molecular forms of plasma adrenomedullin taken from various sites during angiography in patients with suspected renovascular hypertension (n = 9). RESULTS: There were no differences in plasma and urinary excretions of two molecular forms of adrenomedullin among sexes or ages in normal subjects. There was no daytime variation of plasma two molecular forms of adrenomedullin in normal subjects. Plasma AM-m, AM-Gly and AM-T levels were increased in patients with HT and CRF compared with normal subjects, whereas urinary AM-m, AM-Gly and AM-T excretions were decreased in patients with HT and CRF compared with normal subjects. Urinary AM-m: AM-T ratios were significantly higher than plasma AM-m: AM-T ratios. Plasma AM-m and AM-T levels taken from various veins were similar, and they were significantly higher than those of aorta, although there were no differences in plasma AM-Gly levels between aorta and veins. CONCLUSIONS: These results suggest that in normal subjects, and individuals with HT and CRF: (i) plasma and urinary excretions of AM-m and AM-Gly are not affected by age or sex; (ii) AM-m in parallel with AM-Gly is increased; (iii) urine contains a higher percentage of active adrenomedullin than plasma; and (iv) plasma AM-m may be partly metabolized in the lung.

Adrenomedullin↗

PubMed2001

Analysis of pathological tremors using the autoregression model.

The usefulness of analysis of acceleration data using an autoregression model (AR) for differential diagnosis of Parkinson's disease and other diseases with tremors was investigated. The order of the AR model used in this study was 7, in accordance with Akaike's final prediction error criterion. The subjects included 19 patients with Parkinson's disease; 21 patients with essential tremor, which mainly appears in old people, as well as Parkinson's disease; and 13 healthy old people as a control group. The results of analysis of acceleration data showed that the first prediction coefficient, just as the main tremor frequency, was a useful parameter for differentiating patients in the Parkinson's disease patient group and essential tremor patient group. The seventh prediction coefficient was found to be a useful parameter for distinguishing pathological tremors observed in Parkinson's disease and essential tremor disease from physiological tremors observed in healthy people. Although the usefulness of other prediction coefficients for differential diagnosis of Parkinson's disease and other diseases with tremors has not yet been clarified, the results of this study showed that information obtained from AR model parameters in addition to information on main tremor frequency is useful for the diagnosis of Parkinson's disease.

Acceleration↗

PubMed2001

Opposite effects of microtubule-stabilizing and microtubule-destabilizing drugs on biogenesis of mitochondria in mammalian cells.

Distribution of mitochondria as well as other intracellular organelles in mammalian cells is regulated by interphase microtubules. Here, we demonstrate a role of microtubules in the mitochondrial biogenesis using various microtubule-active drugs and human osteosarcoma cell line 143B cells and rat liver-derived RL-34 cells. Depolymerization of microtubules by nocodazole or colchicine, as well as 2-methoxyestradiol, a natural estrogen metabolite, arrested asynchronously cultured cells in G(2)/M phase of cell cycle and at the same time inhibited the mitochondrial mass increase and mtDNA replication. These drugs also inhibited the mitochondrial mass increase in the cells that were synchronized in cell cycle, which should occur during G(1) to G(2) phase progression in normal conditions. However, stabilization of microtubules by taxol did not affect the proliferation of mitochondria during the cell cycle, yet a prolonged incubation of cells with taxol induced an abnormal accumulation of mitochondria in cells arrested in G(2)/M phase of cell cycle. Taxol-induced accumulation of mitochondria was not only demonstrated by mitochondria-specific fluorescent dyes but also evidenced by the examination of cells transfected with yellow fluorescent protein fused with mitochondrial targeting sequence from subunit VIII of human cytochrome c oxidase (pEYFP) and by enhanced mtDNA replication. Two subpopulations of mitochondria were detected in taxol-treated cells: mitochondria with high Delta(psi)(m), detectable either by Mito Tracker Red CMXRos or by Green FM, and those with low Delta(psi)(m), detectable only by Green FM. However, taxol-induced increases in the mitochondrial mass and in the level of acetylated (alpha)-tubulin were abrogated by a co-treatment with taxol and nocodazole or taxol and colchicine. These data strongly suggest that interphase microtubules may be essential for the regulation of mitochondrial biogenesis in mammalian cells.

Animals↗

PubMed2000

Swelling of free-radical-induced megamitochondria causes apoptosis.

Recently, we have found that cultured cells from various sources exposed to free radicals become apoptotic in the presence of megamitochondria (MG). The purpose of the present study is to answer the following two questions: (1) Do functions obtained from the "MG fraction" isolated from normal mitochondria by a routine procedure represent the functions of MG since the fraction consists of enlarged and normal-size mitochondria? (2) What is the correlation between MG formation and apoptotic changes of the cell? In the present study the heavy fraction rich in mitochondria enlarged to varying degrees and the light fraction consisting mainly of normal-size mitochondria were isolated independently from the livers of rats treated with hydrazine for 4 days (4H animals) and 8 days (8H animals), and some functions related to apoptosis were compared. Results were as follows: (1) Mitochondria in both fractions obtained from 8H animals swelled far less in various media than those obtained from the controls, suggesting that the permeability transition pores had been opened before they were exposed to swelling media. (2) The membrane potential of mitochondria in both fractions obtained from 8H animals was distinctly decreased. (3) The rates of reactive oxygen species generation from mitochondria of both fractions in 4H animals were equally elevated, while those in 8H animals were equally decreased compared to those of controls. These results, together with morphological data obtained in the present study, suggest that enlarged and normal-size mitochondria are a part of MG and that the secondary swelling of MG causes the apoptotic changes in the cell.

Animals↗

PubMed2000

Vestibular and cochlear toxicity of aminoglycosides--a review.

Recently, there have been many reports describing the efficacy of intratympanic aminoglycoside injection for the treatment of intractable vertigo in patients with Ménière's disease. However, the number of injections and the amount of drug injected varies, with concomitant variation in the side-effect of hearing deterioration. To identify drugs that are more selectively vestibulotoxic, we have reviewed the ototoxicity of aminoglycosides, focusing on differences between vestibulo- and cochleotoxicity. At present, the basis for the different effects of each drug is unknown. The mechanisms of vestibulo- and cochleotoxicity are deemed worthy of further study.

Aminoglycosides↗

PubMed1999

Cycloheximide and 4-OH-TEMPO suppress chloramphenicol-induced apoptosis in RL-34 cells via the suppression of the formation of megamitochondria.

Toxic effects of chloramphenicol, an antibiotic inhibitor of mitochondrial protein synthesis, on rat liver derived RL-34 cell line were completely blocked by a combined treatment with substances endowed with direct or indirect antioxidant properties. A stable, nitroxide free radical scavenger, 4-hydroxy-2,2,6, 6-tetramethylpiperidine-1-oxyl, and a protein synthesis inhibitor, cycloheximide, suppressed in a similar manner the following manifestations of the chloramphenicol cytotoxicity: (1) Oxidative stress state as evidenced by FACS analysis of cells loaded with carboxy-dichlorodihydrofluorescein diacetate and Mito Tracker CMTH2MRos; (2) megamitochondria formation detected by staining of mitochondria with MitoTracker CMXRos under a laser confocal microscopy and electron microscopy; (3) apoptotic changes of the cell detected by the phase contrast microscopy, DNA laddering analysis and cell cycle analysis. Since increases of ROS generation in chloramphenicol-treated cells were the first sign of the chloramphenicol toxicity, we assume that oxidative stress state is a mediator of above described alternations of RL-34 cells including MG formation. Pretreatment of cells with cycloheximide or 4-hydroxy-2,2, 6,6-tetramethylpiperidine-1-oxyl, which is known to be localized into mitochondria, inhibited the megamitochondria formation and succeeding apoptotic changes of the cell. Protective effects of cycloheximide, which enhances the expression of Bcl-2 protein, may further confirm our hypothesis that the megamitochondria formation is a cellular response to an increased ROS generation and raise a possibility that antiapoptotic action of the drug is exerted via the protection of the mitochondria functions.

Animals↗

PubMed1999

Free radical-induced megamitochondria formation and apoptosis.

Pathophysiological meaning and the mechanism of the formation of megamitochondria (MG) induced under physiological and pathological conditions remain obscure. We now provide evidence suggesting that the MG formation may be a prerequisite for free radical-mediated apoptosis. MG were detected in primary cultured rat hepatocytes, rat liver cell lines RL-34 and IAR-20 and kidney cell line Cos-1 treated for 22 h with various chemicals known to generate free radicals: hydrazine, chloramphenicol, methyl-glyoxal-bis-guanylhydrazone, indomethacin, H2O2, and erythromycin using a fluorescent dye Mito Tracker Red CMXRos (CMXRos) for confocal laser microscopy and also by electron microscopy. Remarkable elevations of the intracellular level of reactive oxygen species (ROS), monitored by staining of cells with a fluorescent dye carboxy-H2-DCFDA, were detected before MG were formed. Prolongation of the incubation time with various chemicals, specified above, for 36 h or longer has induced distinct structural changes of the cell, which characterize apoptosis: condensation of nuclei, the formation of apoptotic bodies, and the ladder formation. Cells treated with the chemicals for 22 h were arrested in G1 phase, and apoptotic sub-G1 populations then became gradually increased. The membrane potential of MG induced by chloramphenicol detected by CMXRos for flow cytometry was found to be decreased compared to that of mitochondria in control cells. Rates of the generation of H2O2 and O2- from MG isolated from the liver of rats treated with chloramphenicol or hydrazine were found to be lower than those of mitochondria of the liver of control animals. We suggest, based on the present results together with our previous findings, that the formation of MG may be an adaptive process at a subcellular level to unfavorable environments: when cells are exposed to excess amounts of free radicals mitochondria become enlarged decreasing the rate of oxygen consumption. Decreases in the oxygen consumption of MG may result in decreases in the rate of ROS production as shown in the present study. This will at the same time result in decreases in ATP production from MG. If cells are exposed to a large amount of free radicals beyond a certain period of time, lowered intracellular levels of ATP may result in apoptotic changes of the cell.

Animals↗

PubMed1999

Two types of the enlargement of mitochondria related to apoptosis: simple swelling and the formation of megamitochondria.

Our recent finding that free radical-induced formation of megamitochondria (MG) is followed by apoptosis has prompted us to investigate the correlation between the MG formation and the swelling of mitochondria which is considered to play a key role in early stages of apoptotic processes of the cell. Mitochondria of rat hepatocytes or RL-34 cells and those isolated from rat livers became enlarged up to three times in their diameters when they were exposed to a hypotonic medium. MG induced in the liver of rats placed on a 1% hydrazine-diet for 4-5 days or those induced in the liver of mice placed on a 2% chloramphenicol (CP)-diet for 9-10 days were endowed with a dense matrix whereas those fed with the toxic diets for longer periods of time became enlarged further and their matrix became extremely pale indicating that MG in the latter animals became swollen secondarily. The membrane potential, the content of cytochrome c and the rate of the generation of reactive oxygen species (ROS) of MG in the former animals were almost unchanged compared to those of mitochondria in control animals whereas those of MG in the latter animals became distinctly decreased. These results may suggest that free radical-induced MG possibly cause apoptosis via their secondary swelling.

Animals↗

PubMed1999

Insertion/deletion angiotensin converting enzyme gene polymorphism affects the microvascular structure of the kidney in patients with nondiabetic renal disease.

OBJECTIVE: It has been reported that the deletion allele of the insertion/deletion polymorphism of the angiotensin I converting enzyme gene is associated with increased cardiovascular risk and progressive renal disease, including immunoglobulin A nephropathy. We therefore investigated the relationship between angiotensin converting enzyme polymorphism and intrarenal microvascular structure in 56 patients with nondiabetic renal disease. METHODS AND RESULTS: We determined various cardiovascular hormones of the renin-angiotensin system and angiotensin converting enzyme gene polymorphism in 56 patients with nondiabetic renal diseases who underwent a renal biopsy. The patients were divided into three groups by angiotensin converting enzyme genotype (insertion/insertion, n = 21; insertion/deletion, n = 23; deletion/deletion, n = 12) using polymerase chain reaction methods. The angiotensin converting enzyme insertion/ deletion and deletion/deletion genotypes were associated with a significantly higher interlobular artery wall : lumen ratio than the insertion/insertion genotype (insertion/insertion 0.27 +/- 0.01, insertion/deletion 0.32 +/- 0.01, deletion/deletion 0.33 +/- 0.02; P < 0.05). Afferent arteriolar and tubulo-interstitial injury scores were similar among the three genotypes. Although serum angiotensin converting enzyme activity was higher in the deletion/deletion than in the other two genotypes (insertion/insertion 9.7 +/- 0.7, insertion/deletion 10.7 +/- 0.9, deletion/deletion 14.0 +/- 2.4 IU/I; P < 0.05), other factors of the renin-angiotensin system, including blood pressure and serum creatinine levels, were not different among the three groups. CONCLUSIONS: The angiotensin converting enzyme deletion/deletion genotype may be considered a risk factor for the development of microvascular wall thickening in nondiabetic renal diseases.

Adult↗

PubMed1996

Change of the sex-dependent response to clofibrate in F344 rat liver during postnatal development.

Although it has been reported that male rats are more responsive than females to peroxisome proliferation induced by clofibrate, these sex differences have been confirmed in young adult rats. Using 4-, 8-, and 12-week-old F344 rats, postnatal change of the sex-dependent response to clofibrate was investigated. These animals were administered 200 mg/kg body wt./day clofibrate by gavage for 7 days. In 4-week-old rats clofibrate-dependent changes (hepatomegaly, induction of hepatic microsomal and peroxisomal enzymes, proliferation of smooth endoplasmic reticulum and peroxisomes of hepatocytes) were slight in both sexes. In 8- and 12-week-old rats clofibrate-induced changes of males were moderate, whereas those of females were slight. These results suggest that the responsiveness of immature rat to clofibrate is weak and in males the susceptibility is gradually strong during postnatal development.

Administration, Oral↗