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T Hisano

Publications and source records attributed to T Hisano.

At least 19 recordsLinked to original sources
PubMed2001

Crystallization and preliminary X-ray analysis of (R)-specific enoyl-CoA hydratase from Aeromonas caviae involved in polyhydroxyalkanoate biosynthesis.

Dimeric (R)-specific enoyl-coenzyme A (CoA) hydratase from Aeromonas caviae catalyzes the hydration of trans-2-enoyl-CoAs with carbon lengths of 4-6 to yield their corresponding (R)-3-hydroxyacyl-CoAs and is essential for polyhydroxyalkanoate (PHA) biosynthesis. The enzyme has been crystallized by vapour diffusion against a reservoir solution containing 20% polyethylene glycol 4000, 5% 2-propanol and 20 mM HEPES pH 7.0 at 298 K. Crystals belong to the monoclinic space group C2, with unit-cell parameters a = 111.54 (3), b = 59.29 (1), c = 47.27 (4) A, beta = 113.04 (2) degrees and contain a dimeric molecule in the asymmetric unit. Flash-cooling of a crystal at 100 K alters its unit-cell parameters to a = 109.82 (7), b = 57.98 (6), c = 46.84 (2) A, beta = 112.71 (3) degrees. Native data to a resolution of 1.7 A have been collected with 94.5% completeness and an R(merge) of 4.0% under cryogenic (100 K) conditions using synchrotron radiation.

Aeromonas↗
PubMed2000

Inhibition of the human intermediate conductance Ca(2+)-activated K(+) channel, hIK1, by volatile anesthetics.

Ca(2+)-activated K(+) channels (K(Ca)) regulate a wide variety of cellular functions by coupling intracellular Ca(2+) concentration to membrane potential. There are three major groups of K(Ca) classified by their unit conductances: large (BK), intermediate (IK), and small (SK) conductance of channels. BK channel is gated by combined influences of Ca(2+) and voltage, while IK and SK channels are gated solely by Ca(2+). Volatile anesthetics inhibit BK channel activity by interfering with the Ca(2+) gating mechanism. However, the effects of anesthetics on IK and SK channels are unknown. Using cloned IK and SK channels, hIK1 and hSK1-3, respectively, we found that the currents of hIK1 were inhibited rapidly and reversibly by volatile anesthetics, whereas those of SK channels were not affected. The IC(50) values of the volatile anesthetics, halothane, sevoflurane, enflurane, and isoflurane for hIK1 inhibition were 0.69, 0.42, 1.01 and 1.03 mM, respectively, and were in the clinically used concentration range. In contrast to BK channel, halothane inhibition of hIK1 currents was independent of Ca(2+) concentration, suggesting that Ca(2+) gating mechanism is not involved. These results demonstrate that volatile anesthetics, such as halothane, enflurane, isoflurane, and sevoflurane, affect BK, IK, and SK channels in distinct ways.

Anesthetics, Inhalation↗
PubMed2000

Changes in diffusion-weighted MRI after status epilepticus.

A 3-year-old male developed hemiplegia and aphasia after convulsive status epilepticus. Diffusion-weighted magnetic resonance images demonstrated cytotoxic edema in the white matter 6 days after the seizure episode and subsequently in the gray matter after an additional 7 days. Diffusion-weighted magnetic resonance images demonstrated a subacute evolution of the pathologic process after the status epilepticus.

Brain Edema↗
PubMed1999

Doppler echocardiographic evaluation of the hemodynamics in absent aortic valve.

Hemodynamics were estimated by Doppler echocardiography in a neonate with an absent aortic valve and absent or extremely hypoplastic mitral valve. The coronary blood flow depended on the increased end-diastolic pressure of the left ventricle. Pulmonary venous congestion, which was also due to the increased end-diastolic pressure of the left ventricle, may induce decreased oxygen saturation and, subsequently, further myocardial hypoxia, poor contraction and increased end-diastolic pressure of the left ventricle. Finally, hypoxic blood was supplied to each organ from the pulmonary artery through the ductus arteriosus, which induced severe acidosis and differential cyanosis after birth.

Aortic Valve↗
PubMed1998

Crystal structures of reaction intermediates of L-2-haloacid dehalogenase and implications for the reaction mechanism.

Crystal structures of L-2-haloacid dehalogenase from Pseudomonas sp. YL complexed with monochloroacetate, L-2-chlorobutyrate, L-2-chloro-3-methylbutyrate, or L-2-chloro-4-methylvalerate were determined at 1.83-, 2.0-, 2.2-, and 2.2-A resolutions, respectively, using the complex crystals prepared with the S175A mutant, which are isomorphous with those of the wild-type enzyme. These structures exhibit unique structural features that correspond to those of the reaction intermediates. In each case, the nucleophile Asp-10 is esterified with the dechlorinated moiety of the substrate. The substrate moieties in all but the monochloroacetate intermediate have a D-configuration at the C2 atom. The overall polypeptide fold of each of the intermediates is similar to that of the wild-type enzyme. However, it is clear that the Asp-10-Ser-20 region moves to the active site in all of the intermediates, and the Tyr-91-Asp-102 and Leu-117-Arg-135 regions make conformational changes in all but the monochloroacetate intermediates. Ser-118 is located near the carboxyl group of the substrate moiety; this residue probably serves as a binding residue for the substrate carboxyl group. The hydrophobic pocket, which is primarily composed of the Tyr-12, Gln-42, Leu-45, Phe-60, Lys-151, Asn-177, and Trp-179 side chains, exists around the alkyl group of the substrate moiety. This pocket may play an important role in stabilizing the alkyl group of the substrate moiety through hydrophobic interactions, and may also play a role in determining the stereospecificity of the enzyme. Moreover, a water molecule, which is absent in the substrate-free enzyme, is present in the vicinities of the carboxyl carbon of Asp-10 and the side chains of Asp-180, Asn-177, and Ala-175 in each intermediate. This water molecule may hydrolyze the ester intermediate and its substrate. These findings crystallographically demonstrate that the enzyme reaction proceeds through the formation of an ester intermediate with the enzyme's nucleophile Asp-10.

Binding Sites↗
PubMed1997

Two forms of hemitonic seizure in patients with infantile hemiplegia and epilepsy.

Two forms of unilateral tonic (hemitonic) seizure were observed in two adult epileptic patients with infantile hemiplegia. Their ictal EEGs showed diffuse bilaterally synchronous spike bursts without focal features. In one case, a 31-year-old male, the VTR/EEG recording clearly demonstrated hemitonic seizure which simultaneously involved his paretic limbs and body and were associated with loss of consciousness and autonomic signs. In the other case, a 33-year-old male, partial seizures with secondary unilateral generalization were demonstrated by VTR/EEG recording. The reason why these cases do not exhibit motor seizure activity on the unaffected side despite diffuse bilateral EEG changes, a lower motor threshold in the paretic limbs and inhibitory effect in the brain-stem on undamaged side are postulated. These two cases suggest that hemitonic seizures include heterogeneous characteristics of partial and generalized epilepsy. In patients with diffuse brain damage, such as those with infantile hemiplegia, seizures appear to exhibit complicated patterns, with characteristics of partial and generalized seizures. There is a gradiation of expression of unilateral seizure, range from clearly partial seizures to those with mostly features of generalized seizures, except for an asymmetry of motor expression.

Adult↗
PubMed1996

Increased expression of T-plastin gene in cisplatin-resistant human cancer cells: identification by mRNA differential display.

The cellular resistance to the potent anticancer agent cis-diamminedichloroplatinum(II) (cisplatin) is thought to be mediated by multiple mechanisms. The technique of differential display of mRNAs was applied to various cisplatin-resistant cell lines and the corresponding parental sensitive human bladder, prostatic, and head and neck cancer cells in order to identify genes that underlie cisplatin resistance. Twenty-four clones were confirmed by Northern blot analysis to be expressed differentially between resistant and the corresponding sensitive cells. Partial DNA sequences of the eight clones that showed a threefold or greater increase in expression in either the resistant cells (seven clones) or sensitive cells (one clone) revealed that two were derived from the T-plastin gene and one from the tissue factor gene. The abundance of T-plastin mRNA in cisplatin-resistant T24/DDP10 cell was approximately 12 times that in the parental T24 cells. Transfection of T24/DDP10 cells with a vector encoding full-length T-plastin antisense RNA demonstrated that reduced T-plastin expression was associated with increased sensitivity to cisplatin. These results are consistent with the hypothesis that several mechanisms participate cooperatively in the acquisition of cisplatin resistance in human cancer.

Antineoplastic Agents↗
PubMed1996

Crystal structure of L-2-haloacid dehalogenase from Pseudomonas sp. YL. An alpha/beta hydrolase structure that is different from the alpha/beta hydrolase fold.

L-2-Haloacid dehalogenase catalyzes the hydrolytic dehalogenation of L-2-haloalkanoic acids to yield the corresponding D-2-hydroxyalkanoic acids. The crystal structure of the homodimeric enzyme from Pseudomonas sp. YL has been determined by a multiple isomorphous replacement method and refined at 2.5 A resolution to a crystallographic R-factor of 19.5%. The subunit consists of two structurally distinct domains: the core domain and the subdomain. The core domain has an alpha/beta structure formed by a six-stranded parallel beta-sheet flanked by five alpha-helices. The subdomain inserted into the core domain has a four helix bundle structure providing the greater part of the interface for dimer formation. There is an active site cavity between the domains. An experimentally identified nucleophilic residue, Asp-10, is located on a loop following the amino-terminal beta-strand in the core domain, and other functional residues, Thr-14, Arg-41, Ser-118, Lys-151, Tyr-157, Ser-175, Asn-177, and Asp-180, detected by a site-directed mutagenesis experiment, are arranged around the nucleophile in the active site. Although the enzyme is an alpha/beta-type hydrolase, it does not belong to the alpha/beta hydrolase fold family, from the viewpoint of the topological feature and the position of the nucleophile.

Amino Acid Sequence↗
PubMed1996

Pit structure on bacterial cell surface.

The yellow-pigmented bacterium isolated from a ditch was a gram negative rod with a G+C content of 63 mol%, and was classified in the genus Sphingomonas. Electron microscopy revealed that the bacterial cell surface was covered with many large plaits. When grown in a medium containing a polysaccharide as an essential nutrient, a pit of 0.02-0.1 micrometers in diameter was formed on the cell surface, and a thin section showed the rearrangement of the plaits and the presence of a region where the cell membrane sinks into the cytosol. The dependence of the pit formation on the presence of macromolecule may predict the existence of a direct uptake mechanism for macromolecules through a mouth-like pit, possibly in endocytosis fashion. The confirmation of the pit structure is the first such finding in the history of microbiology and may provide a new insight into the cell morphology and biochemistry of macromolecule transport in microbial cell system.

Alginates↗
PubMed1996

Crystallization and preliminary x-ray crystallographic studies of L-2-haloacid dehalogenase from Pseudomonas sp. YL.

The dimeric L-2-haloacid dehalogenase from Pseudomonas sp. YL, (subunit mass, 26179 Da), has been crystallized by vapor diffusion, supplemented by repetitive seeding, against a 50 mM potassium dihydrogenphosphate solution (pH 4.5) containing 15% (w/v) polyethylene glycol 8,000 and 1% (v/v) n-propanol. The crystals belong to the monoclinic space group C2 with unit cell dimensions of a = 92.21 angstrom, b = 62.78 angstrom, c = 50.84 angstrom, and beta = 122.4 degrees, and contain two dehalogenase dimers in the unit cell. They are of good quality and diffract up to 1.5 angstrom resolution.

Crystallography, X-Ray↗
PubMed1996

Overexpression of multidrug resistance protein gene in human cancer cell lines selected for drug resistance to epipodophyllotoxins.

Overexpression of either the multidrug resistance 1 (MDR1) gene or multidrug resistance protein (MRP) gene is involved in acquisition of multidrug-resistant phenotypes in human cancer cells. In this study we examined whether selection for resistance to the epipodophyllotoxins, etoposide/teniposide (VP16/VM26), could induce overexpression of MDR1 or MRP. We have previously isolated two VP16/VM26-resistant KB cell lines. Two VP16/VM26-resistant KB cell lines, KB/VM-1 and KB/ VM-4, which were selected by stepwise exposure to VM26 had decreased accumulation of [3H]VP16 and increased levels of MRP, but no apparent expression of MDR1 gene was observed. Another VP16/VM26-resistant KB cell line, KB/VP-4, which was further isolated from a VP16-resistant KB cell line, KB/VP-2, had decreased accumulation of [3H]VP16 and showed overexpression of MRP gene, but not that of MDR1 gene. We also isolated a VP16-resistant cell line, IN157/VP-1, from a human glioma cell line IN157. IN157/VP-1 cells showed decreased accumulation of [3H]VP16 and overexpression of MRP gene, but not of MDR1. These findings suggest that selection for resistance to VP16/VM26, preferentially induces overexpression of MRP gene.

ATP-Binding Cassette Transporters↗
PubMed1996

Systemic anaphylaxis after eating storage-mite-contaminated food.

We describe 2 cases in whom systemic anaphylaxis developed shortly after they had eaten food contaminated by a storage mite, Tyrophagus putrescentiae. We were able to demonstrate that these cases were sensitive to the storage mites but not to food allergens, leading us to conclude that the cases' anaphylactic episodes were the result of ingestion of the storage mites. This is the first report of the ingestion of storage mites causing systemic anaphylaxis in sensitive persons.

Adolescent↗
PubMed1994

Re-evaluation of classic senile plaques by three-dimensional analysis.

We evaluated the proportion of classic plaques among all of the senile plaques in four Alzheimer brains (frontal, temporal, occipital and hippocampal areas) by the usual method of two-dimensional analysis using a single methenamine silver-stained section and three-dimensional analysis using a set of serial sections. Three-dimensional analysis showed the number and percentage of classic plaques to be 2-5 times greater than those revealed by two-dimensional analysis. In the hippocampal area of one case, no classic plaques were found by two-dimensional analysis but three-dimensional analysis showed that some classic plaques were present. From these findings, it is suggested that three-dimensional analysis using serial sections is indispensable for subclassifying senile plaques.

Aged↗
PubMed1994

Microtubule reorganization and lysosome redistribution by a viral v-src oncogene, in mouse Balb/3T3 cells expressing human EGF receptor.

The epidermal growth factor (EGF)-induced endocytosis of its receptor is an obligatory pathway for the cellular regulation of the EGF-specific receptor (EGF-R). BNER4 is a mouse Balb/3T3 cell line transfected with human EGF-R complementary DNA (cDNA). B4/src-13 and B4/src-24 are BNER4 cells transfected with a viral oncogene v-src. Indirect immunofluorescence study demonstrated that EGF-R was mostly localized at the perinuclear region in BNER4 cells at 60 min after EGF addition, whereas it was diffusely distributed throughout the cytoplasm in its v-src transfectants. Double indirect immunofluorescence study further confirmed that EGF-R was localized in lysosomes in BNER4 and B4/src-13 cells at 60 min after EGF addition. Intracellular distribution of the Golgi apparatus, clathrin-coated vesicles and early endosomes were similar in all cell lines. However, the lysosomes detected by anti-lysosomal membrane protein (LGP85) antibodies were diffusely distributed throughout the cytoplasm in the v-src transfectacts. By contrast, in the parental BNER4 cells, the lysosomes were mostly localized in the perinuclear region. The organization of microtubules, but not of actin, was markedly different between BNER4 cells and its v-src transfectants. Nocodazole, which depolymerizes microtubules, altered the distribution of the lysosomes and EGF-R in BNER4 cells. Both intracellular lysosome distribution and microtubule organization in nocodazole-treated BNER4 cells were found to be similar to those in its v-src transfectants without nocodazole treatment. These findings support the notion that changes in lysosome distribution may be correlated with microtubule reorganization by v-src in mouse Balb/3T3 cells.

3T3 Cells↗
PubMed1993

Classification of senile plaques by three-dimensional analysis.

We evaluated the number of each senile plaque subtype in Alzheimer's brain by the usual two-dimensional analysis using a single, methenamine silver stained section and three-dimensional analysis using serial section reconstruction. The number of classic plaques was underestimated due to a lack of precision in the usual evaluating procedures (two-dimensional analysis), while that of stellate deposits was overestimated. From these results, it was suggested that the three-dimensional analysis by gapless serial sections was indispensable to examine and subclassify senile plaques.

Alzheimer Disease↗
PubMed1993

Examination of beta-protein deposits in Alzheimer's cerebral cortices by three-dimensional observation.

We examined the location of beta-protein deposits (small diffuse plaques) in the cerebral cortices of Alzheimer's patients and aged nondemented controls by observing the methenamine silver stained serial sections. Some vessels, astrocytes or neuronal elements existed near or within the diffuse plaques, and the preamyloids in the plaques were frequently detected in direct contact with vessels, astrocytes or neuronal elements. Although these findings do not demonstrate that the beta-protein within the senile plaques is produced in various cellular elements of the brain, they suggest some associations between beta-protein deposition and vessels, astrocytes or neuronal elements.

Aged↗