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T Kurihara

Publications and source records attributed to T Kurihara.

At least 19 recordsLinked to original sources
PubMed1992

Peroxisomal acetoacetyl-CoA thiolase of an n-alkane-utilizing yeast, Candida tropicalis.

Two genes encoding acetoacetyl-CoA thiolase (thiolase I; EC 2.3.1.9), whose localization in peroxisomes was first found with an n-alkane-utilizing yeast, Candida tropicalis, were isolated from the lambda EMBL3 genomic DNA library prepared from the yeast genomic DNA. Nucleotide sequence analysis revealed that both genes contained open reading frames of 1209 bp corresponding to 403 amino acid residues with methionine at the N-terminus, which were named as thiolase IA and thiolase IB. The calculated molecular masses were 41,898 Da for thiolase IA and 41,930 Da for thiolase IB. These values were in good agreement with the subunit mass of the enzyme purified from yeast peroxisomes (41 kDa). There was an extremely high similarity between these two genes (96% of nucleotides in the coding regions and 98% of amino acids deduced). From the amino acid sequence analysis of the purified peroxisomal enzyme, it was shown that thiolase IA and thiolase IB were expressed in peroxisomes at an almost equal level. Both showed similarity to other thiolases, especially to Saccharomyces uvarum cytosolic acetoacetyl-CoA thiolase (65% amino acids of thiolase IA and 64% of thiolase IB were identical with this thiolase). Considering the evolution of thiolases, the C. tropicalis thiolases and S. uvarum cytosolic acetoacetyl-CoA thiolase are supposed to have a common origin. It was noticeable that the carboxyl-terminal regions of thiolases IA and IB contained a putative peroxisomal targeting signal, -Ala-Lys-Leu-COOH, unlike those of other thiolases reported hitherto.

Acetyl-CoA C-Acetyltransferase↗
PubMed1992

Origin of brain 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet.

The present study established that 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet common to mammalian brain originates from an alternative splicing. Peptides specific to the predicted larger translation product were synthesized and antisera against these peptides were prepared. Immunostaining of SDS/PAGE blots showed that the antisera react with the larger protein, but not with the smaller protein, of 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet in all mammals studied.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1992

A long synthetic peptide containing a nuclear localization signal and its flanking sequences of SV40 T-antigen directs the transport of IgM into the nucleus efficiently.

Synthetic short peptides containing only the nuclear localization signal (NLS) direct the transport of nonnuclear proteins into the nucleus. As a conjugate of the synthetic peptide with immunoglobulin M (IgM) did not enter the nucleus, there was believed to be a size limit for nuclear transport of NLS-conjugated proteins. However, we found that IgM conjugated with purified nucleoplasmin, a nuclear protein of Xenopus oocytes, rapidly accumulated in the nucleus. For direct comparison with the short peptide, we prepared a long peptide containing the NLS and its flanking sequences of SV40 large T-antigen and its mutated long peptide, in which possible phosphorylation sites located at the amino terminal of the NLS were changed to alanine. Kinetic experiments showed that wild-type long peptide-IgM conjugates were almost entirely taken up into the nucleus within 30 min after their injection, whereas almost 60 min was required for the mutated long peptide-IgM conjugates to enter the nucleus of all the cells examined, and there was no apparent accumulation of short peptide-IgM conjugates in the nucleus within 60 min. These results indicate that even when the kinetics of transport are affected by amino acid substitutions, the long peptide directs the transport of large molecules such as IgM into the nucleus.

Amino Acid Sequence↗
PubMed1992

Relationship between endothelin and thromboxane A2 in rat liver microcirculation.

In our previous study, we determined changes in hepatic blood flow using a Laser Doppler blood flow meter after i.v. injection of endothelin-1 (ET-1) or endothelin-3 (ET-3) at 2 nmol/kg in rats and found that ET-3 caused greater decreases in blood flow than ET-1. In the present study, we determined how the arachidonic acid cascade, mainly thromboxane A2 (TXA2), is related to ET-1 and ET-3 using indomethacin (INDO), which inhibits the biosynthesis of prostaglandin (PG), and OKY-046, a selective inhibitor of TXA2 synthesis. In the first series of experiments, ET-1 and ET-3 were administered after inhibiting the biosynthesis of PG by s.c. injection of 2 mg/kg of INDO. While INDO failed to inhibit the slight decrease in hepatic blood flow induced by ET-1, it significantly inhibited the marked decrease in hepatic blood flow elicited by ET-3. In the next series of experiments, ET-1 and ET-3 were administered after administration of 20 mg/kg of OKY-046. OKY-046 showed no effects in animals treated with ET-1, as in those pre-treated with INDO, while it significantly inhibited the decreases in hepatic blood flow induced by ET-3. These findings suggest that ET-1 decreases hepatic blood flow due to its direct effects although to a lesser extent than ET-3, while ET-3 does so due not only to its direct effects but also to TXA2-mediated effects. It is therefore likely that in addition to ET family peptides, PG-mediated mechanisms are involved in the regulation of hepatic microcirculation by ETs.

Animals↗
PubMed1992

ET-3 sensitive reduction of tissue blood flow in rat liver.

Changes in gastric mucosal and hepatic tissue blood flow were simultaneously determined using a laser-Doppler blood flow meter in rats given i.v. injection of endothelin-1 (ET-1) and endothelin-3 (ET-3), both at 2 nmol/kg. Gastric mucosal blood flow decreased significantly after administration of ET-1 compared to after administration of ET-3. Decreases in blood flow due to ET-1 were reversed by pre-treatment with 10 mg/kg of BQ-123 (sodium salt), an ETA receptor antagonist, to levels comparable to those induced by ET-3, but BQ-123 had no effects on decreases in blood flow due to ET-3. On the other hand, decreases in hepatic tissue blood flow by ET-3 were significant compared to those by ET-1. Decreases in hepatic tissue blood flow due to ET-1 were slightly inhibited by pre-treatment with 10 mg/kg of BQ-123, but it had no effect at all on decreases due to ET-3. These findings indicate that decreases in gastric mucosal blood flow are mainly caused by ET-1 via ETA receptors inhibited by BQ-123, while decreases in hepatic tissue blood flow are caused mainly by ET-3 via non-ETA receptors not inhibited by BQ-123. The fact that ET-3 decreases blood flow more significantly than ET-1 suggests the involvement of ET-3 selective receptors (ETc). The findings obtained in the present study indicate that complex mechanisms are involved in the regulation of tissue blood flow by ET, with different receptor subtypes and ET family peptides being involved according to the type of tissue.

Animals↗
PubMed1992

Enzymatic inactivation of tachykinin neurotransmitters in the isolated spinal cord of the newborn rat.

A mixture of peptidase inhibitors increased the magnitude of the saphenous nerve-evoked slow depolarization of a lumbar ventral root and prolonged the similarly evoked inhibition of monosynaptic reflex (MSR) in the isolated spinal cord of the newborn rat in the presence of naloxone. The saphenous nerve-evoked MSR inhibition was curtailed by a tachykinin antagonist, GR71251, and after the treatment with GR71251, the peptidase inhibitor mixture no more prolonged the MSR inhibition. The present results suggest that enzymatic degradation plays a role in the termination of action of tachykinins released from primary afferents in the newborn rat spinal cord. The results provide a further support for the notion that tachykinins serve as neurotransmitters in the spinal cord of the newborn rat.

Animals↗
PubMed1992

Antibodies against 70-kD heat shock cognate protein inhibit mediated nuclear import of karyophilic proteins.

Previously, we found that anti-DDDED antibodies strongly inhibited in vivo nuclear transport of nuclear proteins and that these antibodies recognized a protein of 69 kD (p69) from rat liver nuclear envelopes that showed specific binding activities to the nuclear location sequences (NLSs) of nucleoplasmin and SV-40 large T-antigen. Here we identified this protein as the 70-kD heat shock cognate protein (hsc70) based on its mass, isoelectric point, cellular localization, and partial amino acid sequences. Competition studies indicated that the recombinant hsc70 expressed in Escherichia coli binds to transport competent SV-40 T-antigen NLS more strongly than to the point mutated transport incompetent mutant NLS. To investigate the possible involvement of hsc70 in nuclear transport, we examined the effect of anti-hsc70 rabbit antibodies on the nuclear accumulation of karyophilic proteins. When injected into the cytoplasm of tissue culture cells, anti-hsc70 strongly inhibited the nuclear import of nucleoplasmin, SV-40 T-antigen NLS bearing BSA and histone H1. In contrast, anti-hsc70 IgG did not prevent the diffusion of lysozyme or 17.4-kD FITC-dextran into the nuclei. After injection of these antibodies, cells continued RNA synthesis and were viable. These results indicate that hsc70 interacts with NLS-containing proteins in the cytoplasm before their nuclear import.

Amino Acid Sequence↗
PubMed1992

Beta-oxidation of butyrate, the short-chain-length fatty acid, occurs in peroxisomes in the yeast Candida tropicalis.

When an n-alkane-utilizable yeast, Candida tropicalis pK233, was cultivated on butyrate, the fatty acid of shortest chain-length for beta-oxidation, as the sole source of carbon and energy, catalase and the enzymes of the fatty acid beta-oxidation system were inducibly synthesized at high levels. As in the alkane-grown cells, the proliferation of peroxisomes was harmonized with the induction of peroxisomal enzymes. The results of subcellular fractionation and immunoelectronmicroscopy indicated the localization of these enzymes in peroxisomes, not in mitochondria. It was suggested that only peroxisomes have a role in fatty acid beta-oxidation in the yeast cells, unlike in mammalian cells, in which cooperation between peroxisomes and mitochondria is essential.

Acetyl-CoA C-Acyltransferase↗
PubMed1992

Physiological roles of acetoacetyl-CoA thiolase in n-alkane-utilizable yeast, Candida tropicalis: possible contribution to alkane degradation and sterol biosynthesis.

The presence of two types of thiolases, acetoacetyl-CoA thiolase and 3-ketoacyl-CoA thiolase, was demonstrated in peroxisomes of n-alkane-grown Candida tropicalis [Kurihara, T., Ueda, M., & Tanaka, A. (1989) J. Biochem. 106, 474-478], while acetoacetyl-CoA thiolase was also shown to be present in cytosol. The activity of the enzyme in cytosol was constant irrespective of culture conditions, while the peroxisomal enzyme was inducibly synthesized in the alkane-grown yeast cells. These results indicate that peroxisomal acetoacetyl-CoA thiolase participates in alkane degradation, while the cytosolic enzyme is associated with other fundamental metabolic processes, probably sterol biosynthesis, because this enzyme can catalyze the first step of the sterol biosynthesis. 3-Hydroxy-3-methylglutaryl (HMG)-CoA reductase, a key regulatory enzyme of sterol biosynthesis, was found to be localized exclusively in microsomes of the alkane-grown yeast cells. These results suggest that yeast peroxisomes do not contribute to sterol biosynthesis, unlike the case of mammalian cells.

Acetyl-CoA C-Acetyltransferase↗
PubMed1992

Transition of phenotypic dimorphism with regard to spontaneous sister chromatid exchange in Epstein-Barr virus-transformed Bloom's syndrome lymphoblastoid cell lines.

We recently established four lymphoblastoid cell lines (LCLs) by infecting the peripheral blood of four Japanese patients suffering from Bloom's syndrome (BS) with Epstein-Barr virus (EBV). During the course of propagating these cell lines, two of them exhibited dimorphism regarding spontaneous sister chromatid exchange (SCE), i.e., a mixed population consisted of cells with extremely high SCE levels characteristic of BS and cells with low SCE levels indistinguishable from that of normal control cells. On the other hand, the other two cell lines maintained a monomorphic population with high SCE levels at least until 30 weeks after EBV infection. The proportion of the cells with high SCE levels in the cell lines with dual phenotype declined as the population doubling numbers (PDN) increased with time and they became ultimately undetectable. The proportion of cells with low SCE levels at the time of EBV infection was estimated in one of these LCLs as 0.075% by extrapolating the linear regression of the logit for the proportion plotted against PDN. In view of the well-known stability of the monomorphic phenotype in representative BS LCLs during extended cultivation, together with the present observations on the dual phenotype, we conclude that the frequent establishment of BS LCLs exclusively with low spontaneous SCE levels is attributable to the various proportions of low-SCE cells existing in vivo in the B-lymphocytes pool of BS individuals and to the selective pressure against the high-SCE cells in in vitro cultures.

Adolescent↗
PubMed1992

[Relationship between hand-washing activity of disinfectants and in vitro bactericidal activity in the presence of peptone].

A study was made on the relation between in vitro bactericidal activity against Staphylococcus epidermidis which is the main bacterial flora of skin and the disinfecting activity of hand-washing with povidone-iodine, sodium hydrochloride, chloramin-T, chlorhexidine gluconate and benzalkonium-chloride. Although the bactericidal activity of povidone-iodine and sodium hydrochloride was significantly high as compared with those of the other three disinfectants, both povidone-iodine and sodium hydrochloride showed no or a little hand-washing effects. In vitro the bactericidal activity of both povidone-iodine and sodium chloride were significantly retarded by the addition of peptone in the reaction mixture. On the other hand, chloramin-T, chlorhexidine gluconate and benzalkonium chloride showed a high disinfecting activity in hand washing in spite of low in vitro bactericidal activity. Moreover, the bactericidal activity of these three disinfectants were not suppressed by the addition of peptone in the reaction mixture. These results strongly suggested that hand washing effect of disinfectant is affected by the protein on the hand and that hand-washing activity of disinfectant should be determined by in vitro bactericidal activity in the presence of peptone.

Chlorhexidine↗
PubMed1992

Immunoelectron microscopic localization of thiolases, beta-oxidation enzymes of an n-alkane-utilizable yeast, Candida tropicalis.

The location of acetoacetyl-CoA thiolase (T-I) and 3-ketoacyl-CoA thiolase (T-III), enzymes of the fatty acid beta-oxidation system, was studied in n-alkane-grown Candida tropicalis cells by immunoelectron microscopy using a post-embedding method with colloidal gold conjugated IgG. The deposition of gold particles for T-I was detected in the microbodies and cytoplasm and that of gold particles for T-III specifically in the microbodies. The double labeling technique confirmed that T-I and T-III occurred concurrently in a microbody and T-I also in cytoplasm. These results were consistent with the biochemical data based on subcellular fractionation and indicated that the yeast beta-oxidation system operates efficiently only in the microbodies.

Acetyl-CoA C-Acetyltransferase↗
PubMed1992

Studies on the constituents of edible and medicinal plants. III. Effects of seven limonoids on the sleeping time induced in mice by anesthetics.

Effects of seven limonoids, obakunone (1), 7 alpha-obakunol (2), 7 beta-obakunol (3), limonin (4), 7 alpha-limonol (5), 7 beta-limonol (6) and nomilin (7), on the sleeping time induced in mice by anesthetics were assayed. All the limonoids, except for 2, shortened the sleeping time induced by alpha-chloralose and urethane. 7 gave the highest reduction rate of sleeping time, and the order of the reduction rate of sleeping time was as follows; 7 > 1 and 3 > 4, 5 and 6. As the chemical structures of these compounds are similar to each other, the relationship between the structure and the effects of limonoids on sleeping time was discussed.

Animals↗
PubMed1992

[Divergence paralysis due to a lesion of the lateral tegmentum of the midbrain caused by thalamic hemorrhage].

A 66-year-old diabetic and hypertensive man suddenly developed right hemiplegia. Examination revealed right hemiplegia including his face, vertical gaze palsy, and divergence paralysis. The cranial CT scan disclosed a left thalamic hemorrhage as large as 40 mm in diameter, which extended to the midbrain. He was treated medically and his divergence paralysis improved. But all other symptoms remained for the next 11 months and he eventually died of acute retroperitoneal hemorrhage. The autopsy revealed spongy state and gliosis extending from the left thalamic nuclei to the left midbrain. In the tegmentum, dorsolateral part around the left oculomotor nucleus was involved. The precise location of the human divergence center of the eyes is still unknown. According to previous reports, the divergence center may locate in the tegmentum of the midbrain or pons. Recently, animal experiments detected the neurons which fire for divergent in the mesencephalic reticular formation just dorsal and lateral to the oculomotor nuclei. Our case had a lesion of gliosis and spongy state, namely the old hematoma, in the same portion. Therefore, we considered that the human divergence center of the eyes might exist in the lateral tegmentum of the midbrain, just lateral and dorsal to the oculomotor nucleus.

Aged↗
PubMed1992

[Left ventricular function assessed by multigated blood pool single photon emission computed tomography with 99mTc].

To evaluate the usefulness of gated blood pool single photon emission computed tomography with 99mTc (gated SPECT) for assessing left ventricular function, we performed gated SPECT in 2 normal subjects and 18 patients including 13 with ischemic heart disease, 3 with hypertrophic cardiomyopathy and 2 with dilated cardiomyopathy. Left ventricular end-diastolic volume (LVEDV), left ventricular ejection fraction (LVEF) and regional wall motion obtained by gated SPECT were compared with the results of contrast left ventriculography (contrast LVG), echocardiography and planar multigated blood pool imaging (planar blood pool). After the patients' red blood cells were labelled with 30 mCi (1,110 MBq) 99mTc in vivo, gated SPECT was performed in each of 32 projections through a 360 degree arc for each of the cardiac cycle divided into 16. From these images, the left ventricular vertical long-axis image, the horizontal long-axis and short-axis images were reconstructed. To calculate LVEDV, we used serial short-axis images which were composed of the left ventricle. To define left ventricular and left atrial borders, we used amplitude images and cinematic displays of the vertical long-axis image. The level of the optimal cut for delineating the left ventricular border was determined from the volume-cut-level-graph at each background activity, which was constructed by a phantom study. Left ventricular wall motion by gated SPECT was compared with the results of contrast LVG according to segmental analysis. LVEDV obtained by gated SPECT showed an excellent linear correlation with LVEDV calculated by echocardiography (r = 0.98, p < 0.01) and by contrast LVG (r = 0.89, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗