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Biomedical subjects

N Shibata

Publications and source records attributed to N Shibata.

At least 109 records · Page 6Linked to original sources
PubMed1999

Advanced glycation endproducts are deposited in neuronal hyaline inclusions: a study on familial amyotrophic lateral sclerosis with superoxide dismutase-1 mutation.

To determine the role of advanced glycation endproducts (AGE) in the pathogenesis of familial amyotrophic lateral sclerosis (ALS) with superoxide dismutase-1 (SOD1) mutation, we investigated the immunohistochemical localization of N(epsilon)-carboxymethyl-lysine (CML), one of the major AGE structures, in spinal cords from three familial ALS patients with a heterozygous Ala to Val substitution at codon 4 in the gene for SOD1. Neuronal hyaline inclusions (NHIs), the abnormal structures seen in some of the remaining lower motor neurons of familial ALS patients with SOD1 mutation, were intensely stained by a monoclonal antibody specific for CML in contrast to the only weakly stained cytoplasm. Immunoelectron microscopy depicted the CML determinants restricted to the granule-associated thick linear structures that mainly compose the NHIs. The NHIs were also recognized by antibodies to SOD1, phosphorylated neurofilament protein and ubiquitin. No focal collection of either CML or SOD1 was found in neurons of the control individuals. Our results indicate that CML is a component of the NHIs of familial ALS patients with SOD1 mutation, and suggest that the CML formation may be mediated by protein glycoxidation or lipid peroxidation in the presence of oxidative stress from mutant SOD1, in association with motor neuron degeneration.

Adult↗
PubMed1999

Astrocytic hyaline inclusions contain advanced glycation endproducts in familial amyotrophic lateral sclerosis with superoxide dismutase 1 gene mutation: immunohistochemical and immunoelectron microscopical analyses.

To clarify the neuropathological significance of the deposition of N(epsilon)-carboxymethyl lysine (CML), an advanced glycation endproduct, in astrocytic hyaline inclusions in familial amyotrophic lateral sclerosis (FALS), autopsy specimens from five members of two different families who had the superoxide dismutase 1 (SOD1) gene mutations were analysed. Immunohistochemically, most of the neuronal and astrocytic hyaline inclusions were intensely stained by the antibody against CML. The distributions and intensities of the immunoreactivities for CML and SOD1 were similar in the inclusions in both cell types. Immunoelectron microscopy showed that both inclusions consisted of CML-positive granule-coated fibrils and granular materials. No significant CML or SOD1 immunoreactivity was observed in the neurons and astrocytes of the normal control subjects. Our results suggest that astrocytic hyaline inclusions contain CML and SOD1 in FALS patients with SOD1 gene mutations, and that the formation of CML-modified protein (probably CML-modified SOD1) is related to the cell degeneration.

Adult↗
PubMed1999

Arrhythmogenic changes in action potential configuration in the ventricle induced by DC shocks.

Failure of defibrillation by direct current (DC) shocks is the result in part of new ventricular tachyarrhythmias induced by the shocks. We investigated the arrhythmogenic substrate produced by the shocks. Fluorescent action potential (AP) signals were recorded from rabbit hearts perfused in vitro with the use of our original optical recording system. Localized application of 10-ms shocks (S2) during the plateau phase of APs by basic stimuli (S1) caused field intensity (FI)-dependent changes in APs: (a) S2 > 7 V/cm caused additional depolarization, giving rise to a prolongation of AP duration (APD); (b) With S2 > 20 V/cm, terminal repolarization was inhibited, and subsequent postshock S1 APs for 1 to 5 min were characterized by decreases in the maximum diastolic potential and amplitude of APs; and (c) S2 > 30 V/cm often resulted in a prolonged refractoriness, oscillation of membrane potential leading to ventricular tachycardia or fibrillation (VT/VF). The right ventricle was more susceptible than other regions for the aftereffects of high-intensity shocks. Using an 8-channel recording system, we compared the effect of 10-ms monophasic (M) and 5/5-ms biphasic (B) shocks applied to the whole ventricles with FI of 1 to 20 V/cm at the signal recording sites. B shocks were less potent than M shocks in the FI-dependent action potential duration (APD) prolongation, and in the shock-induced enhancement of APD dispersion. Incidence and duration of VT/VF induced by M shocks were significantly greater than those by B shocks. These findings suggest that DC shocks will cause two types of arrhythmogenic substrate: one induced at sites of high FI, and the other at sites with moderate FI. The former would produce local block or focal repetitive excitation due to prolonged depolarization and oscillation of membrane potential, and the latter circuitous movement of wavefronts through an enhancement of spatial inhomogeneity of repolarization.

Animals↗
PubMed1999

Immature astrocytes in Fukuyama congenital muscular dystrophy: an immunohistochemical study.

Recent studies of Fukuyama congenital muscular dystrophy have focused on abnormalities of the basement membrane in muscle and brain. The cerebral cortex has a unique basement membrane at the glia limitans, which is intimately related to astrocytes in the developing brain, and the basement membrane may be partially produced by the astrocyte. In this study the cerebral astrocytes in six patients with Fukuyama congenital muscular dystrophy, including two fetal patients, were characterized by immunohistochemical study. In fetal Fukuyama congenital muscular dystrophy, astrocytes reacted less to antibodies of glial fibrillary acidic protein, S-100 protein, and alphaB-crystallin than control astrocytes, but in postnatal Fukuyama congenital muscular dystrophy, astrocytes reacted more to these antibodies and displayed beading of processes. Moreover, vimentin was positive in the astrocytes of two postnatal Fukuyama congenital muscular dystrophy patients. This astrocytic appearance may suggest immaturity of astrocytes in Fukuyama congenital muscular dystrophy. Astrocytes exhibiting beaded cytoplasmic processes were prominent at the subpia of the cortex and around vessels. The authors hypothesize that these immature astrocytes are unable to participate in the function of the cortical basement membrane, which is defective in Fukuyama congenital muscular dystrophy. Studies of neurons and meninges were similar to those of control subjects.

Adolescent↗
PubMed1999

Bone mineral density of epileptic patients on long-term antiepileptic drug therapy: a quantitative digital radiography study.

In order to assess the bone atrophy lesions of epileptic patients, the bone mineral densities (BMDs) of their lumbar spines and femoral necks were measured using quantitative digital radiography (QDR). The study groups were 44 patients on long-term medication for epilepsy and 62 healthy control subjects. We selected patients who had been taking phenytoin, barbiturates, and/or acetazolamide for at least 5 years. BMDs at both sites were significantly lower in the patient group than in the control group. No sex differences were found in BMDs. There were no significant correlations with the onset or the duration of illness and BMD. We compared BMD according to the type of epileptic drug being taken and theorized that phenytoin, barbiturates, and acetazolamide reduced BMD. BMDs of the 15 patients were measured again 7 years later, and were found to be significantly lower at both sites than in the previous examination. These results confirm the presence of bone atrophy lesions in epileptic patients on long-term antiepileptic drugs. Patients on antiepileptic therapy for long periods should have their BMDs checked, because they are prone to developing bone atrophy.

Absorptiometry, Photon↗
PubMed1999

Genetic association between cytochrome P-450 2D6 gene polymorphism and plasma concentration of haloperidol in Japanese schizophrenics.

Haloperidol is one of the major neuroleptics partly metabolized by cytochrome P-450 2D6 (CYP2D6), which has over 10 genetic polymorphisms. The purpose of this study was to investigate whether individual haloperidol plasma concentration was affected by CYP 2D6 gene polymorphisms. The genomic DNA of 56 subjects who have been taking haloperidol were analysed by restriction fragment length polymorphism (RFLP) method to detect the major Caucasian mutations, CYP 2D6A, 2D6B, and the major oriental population mutation, 2D6J. We found 10 cases of the CYP 2D6J mutation, only one case of the CYP 2D6B mutation, and no cases of the CYP 2D6A mutation in the present subjects. Contrary to expectations, haloperidol plasma concentration of the CYP 2D6B mutation case showed a lower haloperidol plasma concentration than the mean value of that of wild type homozygous cases. Haloperidol plasma concentration of 10 subjects who had the CYP 2D6J mutation cases showed no significant difference from that of the wild type homozygous group. These results suggest that the major genetic polymorphisms of CYP 2D6 do not seem to be one of the factors which affect individual haloperidol plasma concentration in Japanese schizophrenics.

Adult↗
PubMed1999

Crystallization and preliminary x-ray study of two crystal forms of Klebsiella oxytoca diol dehydratase-cyanocobalamin complex.

Two crystal forms of Klebsiella oxytoca diol dehydratase complexed with cyanocobalamin have been obtained and preliminary crystallographic experiments have been performed. The crystals belong to two different space groups, depending on the crystallization conditions. One crystal (form I) belongs to space group P212121 with unit-cell parameters a = 76.2, b = 122.3, c = 209. 6 A, and diffracts to 2.2 A resolution using an X-ray beam from a synchrotron radiation source. The other crystal (form II) belongs to space group P21 with unit-cell parameters a = 75.4, b = 132.7, c = 298.8 A, beta = 91.9 degrees, and diffracts to 3.0 A resolution. For the purpose of structure determination, a heavy-atom derivative search was carried out and some mercuric derivatives were found to be promising. Structure analysis by the multiple isomorphous replacement method is now under way.

Bacterial Proteins↗
PubMed1999

Crystallization and preliminary crystallographic studies of FMN-binding protein from Desulfovibrio vulgaris miyazaki F.

The flavin mononucleotide binding protein from Desulfovibrio vulgaris (Miyazaki F) was crystallized using the vapour-diffusion method. The crystal belongs to the monoclinic space group P21 with unit-cell parameters a = 37.2, b = 84.6, c = 41.1 A, beta = 94.1 degrees, contains two molecules per asymmetric unit and diffracts beyond 1.2 A resolution with a synchrotron radiation X-ray source.

Bacterial Proteins↗
PubMed1999

Influence of glycerol-induced acute renal failure on the pharmacokinetics of cyclosporin in rats.

Although it is widely believed that renal dysfunction has no effect on the pharmacokinetics of cyclosporin, many clinical reports suggest that renal dysfunction after renal transplantation is closely related to the pharmacokinetics of cyclosporin. To clarify the relationship between renal dysfunction and the pharmacokinetics of cyclosporin, we examined the influence of acute renal failure (ARF) on its pharmacokinetics in glycerol-induced ARF rats. The values of indicators of renal function (serum creatinine, blood urea nitrogen), but not those of indicators of hepatic function, were significantly increased in ARF rats that received glycerol compared with values for control rats. The area under the blood cyclosporin concentration-time curve after oral administration (AUCpo) were 4.976+/-0.847 mghL(-1) for ARF rats and 9.684+/-1.100 mghL(-1) for control rats; AUCpo in ARF was significantly reduced in a manner dependent on renal function. The oral clearance of cyclosporin in ARF and control rats was 1.172+/-0.207 and 0.544+/-0.062Lh(-1) kg(-1), respectively, whereas total body clearance in ARF and control rats was 0.151+/-0.008 and 0.183+/-0.010Lh(-1)kg(-1), respectively. The relative bioavailability of cyclosporin in ARF and control rats was 0.118 and 0.336, respectively. In an in-vitro study using everted sac and liver-slice methods, the apparent first-order rate constants for cyclosporin uptake (k(uptake)) and metabolism (k(metab)) in gut tissues were reduced, whereas k(uptake) and k(metab) in liver were increased. Gastric emptying, measured by use of paracetamol, was significantly reduced in ARF rats. These results suggest that glycerol-induced ARF results in several changes in the pharmacokinetics of cyclosporin in rats. From these results, we conclude that reduction of the absorbed fraction of cyclosporin strongly contributes to the decrease in AUCpo in the presence of ARF.

Acetaminophen↗
PubMed1999

Surgical stress increases renal glutathione content via increased glucocorticoid, and resistance to subsequent oxidative injury in the rat: significant link between endocrine response and cell defense system under the stress.

Systemic and nonspecific stress response effects on the cellular defense mechanism were studied in the male rat kidney. Two days after laparotomy-induced surgical stress, rats showed increased serum corticosterone and renal cortical reduced glutathione (GSH). Rats were then injected s.c. with mercuric chloride (HgCl2) to oxidatively injure renal tubuli. Increased serum creatinine levels indicated that laparotomy pretreatment lessened renal damage. To study the effects of the activated pituitary-adrenal axis on renal cortical GSH content and vulnerability to subsequent oxidative injury, rats were injected s.c. with ACTH on two consecutive days. ACTH administration increased both corticosterone and aldosterone. These rats showed increased, dose-dependent renal cortical GSH content, i.e., controls (n=7): 1.25 +/- 0.23 micromol/g tissue, daily dose of 10 microg/100 gBW (n=7): 1.53 +/- 0.24 micromol/g tissue, and daily dose of 40 microg/100 gBW (n=7): 2.31 +/- 0.23 micromol/g tissue. Rats receiving daily doses of 40 microg of ACTH/100 gBW acquired resistance to oxidative injury, indicated by serum creatinine levels: controls (n=6), 22 +/- 4 micromol/L; HgCl2 (n=6), 145 +/- 88 micromol/L; ACTH and HgCl2 (n=6), 37 +/- 11 micromol/L. Morphological evidence indicated that ACTH pretreatment in HgCl2-injected rats prevented renal tissue from inflammatory cell infiltration but not from tubular degeneration. Cellular GSH content of LLC-PK1 cells, porcine renal-tubule-derived culture cells, increased significantly in incubation with dexamethasone or aldosterone, suggesting that adrenal steroids directly stimulate renal cell GSH. We demonstrated that stress or ACTH administration activates the defense mechanism in the kidney via increased GSH. This stress-activatable defense system may therefore indicate a connection between endocrine stress response and the cellular defense mechanism.

Adrenocorticotropic Hormone↗
PubMed1999

Percutaneous microwave hepatic tumor coagulation with segmental hepatic blood flow occlusion in seven patients.

OBJECTIVE: We assess the usefulness of microwave hepatic tumor coagulation therapy with balloon occlusion of segmental hepatic blood flow for eight recurrent metastatic hepatic tumors in seven patients. CONCLUSION: Limited early experience with microwave hepatic tumor coagulation therapy and segmental hepatic blood flow occlusion has been positive, suggesting that further clinical evaluation is warranted.

Catheterization↗
PubMed1999

Percutaneous microwave coagulation therapy for hepatocellular carcinoma located on the surface of the liver.

OBJECTIVE: Percutaneous microwave coagulation therapy was recently introduced as a new treatment for hepatocellular carcinoma in our country. We performed this study to evaluate the efficacy and safety of this therapy for treatment of hepatocellular carcinoma, especially for tumors located on the surface of the liver. CONCLUSION: Percutaneous microwave coagulation therapy can be performed safely even in patients with cirrhosis and can achieve complete remission of small hepatocellular carcinomas (< or = 2.0 cm) located on the surface of the liver.

Aged↗
PubMed1999

[Perioperative bleeding tendency in a hemodialysis patient during gastrectomy under total intravenous anesthesia using propofol infusion].

A 64-year-old female receiving hemodialysis (HD) underwent subtotal gastrectomy for gastric cancer under total intravenous anesthesia. Anesthesia was performed using continuous infusion of propofol (5-8 mg.kg-1.h-1), buprenorphine i.v. (2.5 micrograms.kg-1), 2% mepivacaine epidural infusion (7 ml.h-1) and appropriate doses of vecuronium. The blood pressure and heart rate were stable within 120% of the preoperative level. However, 3 and half hours after propofol anesthesia, increased bleeding from the surgical field was observed. The activated clotting time (ACT) was 144 seconds. Furthermore, at the end of the operation (5 hours after propofol anesthesia), the ACT (219 sec), PT (14.8 sec), PT-INR (1.94) and APTT (102.5 sec) were significantly prolonged. The platelet count was unchanged. The intraoperative total bleeding was 844 g. The total propofol infusion time and dose were 310 minutes and 1,580 mg, respectively. Immediate recovery with spontaneous ventilation was observed. Postoperative bleeding from the wound continued. Finally, 7 hours after the surgery, the bleeding ceased and the ACT (125 sec), PT (12.4 sec), PT-INR (1.34) and APTT (22.5 sec) were normalized. The total postoperative bleeding was 404 g. Despite the advantage of short-acting anesthetic agent, we suspect that propofol induced the bleeding tendency via platelet inhibition. This platelet inhibition may gradually increase with time and the dose of propofol. We should utilize propofol cautiously for patients receiving HD or with bleeding tendency.

Anesthesia, Epidural↗
PubMed1998

Basis for monomer stabilization in Rhodopseudomonas palustris cytochrome c' derived from the crystal structure.

The crystal structure of an unusual monomeric cytochrome c' from Rhodopseudomonas palustris (RPCP) has been determined at 2.3 A resolution. RPCP has the four-helix (helices A, B, C and D) bundle structure similar to dimeric cytochromes c'. However the amino acid composition of the surface of helices A and B in RPCP is remarkably different from that of the dimeric cytochromes c'. This surface forms the dimer interface in the latter proteins. RPCP has seven charged residues on this surface contrary to the dimeric cytochromes c', which have only two or three charged groups on the corresponding surface. Moreover, hydrophobic residues on this surface of RPCP are two to three times fewer than in dimeric cytochromes c'. As a result of the difference in amino acid composition, the A-B surface of RPCP is rather hydrophilic compared with dimeric cytochromes c'. We thus suggest that RPCP is monomeric in solution because of the hydrophilic nature of the A-B surface. The amino acid composition of the A-B surface is similar to that of Rhodobacter capsulatus cytochrome c' (RCCP), which is an equilibrium admixture of monomer and dimer. The charge distribution of the A-B surface in RCCP, however, is considerably different from that of RPCP. Due to the difference, RCCP can form dimers by both ionic and hydrophobic interactions. These dimers are quite different from those in proteins which form strong dimers such as in Chromatium vinosum, Rhodospirillum rubrum, Rhodospirillum molischianum and Alcaligenes. Cytochrome c' can be classified into two types. Type 1 cytochromes c' have hydrophobic A-B surfaces and they are globular. The A-B surface of type 2 cytochromes c' is hydrophilic and they take a monomeric or flattened dimeric form.

Amino Acid Sequence↗
PubMed1998

Simultaneous determination of glucocorticoids in plasma or urine by high-performance liquid chromatography with precolumn fluorimetric derivatization by 9-anthroyl nitrile.

A new method for simultaneous determination of glucocorticoids (GCs) in plasma or urine by high-performance liquid chromatography (HPLC) with fluorimetric detection has been developed. Following extraction with ethyl acetate using a reversed-phase disposable cartridge, the six GCs [cortisol (F), cortisone (E), prednisolone (PL), prednisone (PN), 6beta-hydroxycortisol (6beta-OHF) and 6beta-hydroxyprednisolone (6beta-OHP)] and an internal standard (6beta-hydroxycotortisone) were derivatized by treatment with 9-anthroyl nitrile (9-AN) in a mixture of basic catalysts (triethylamine and quinuclidine) to give the fluorescent esters through the 21-hydroxyl group. The GC derivatives so obtained were then cleaned by a straight-phase disposable cartridge and chromatographed on a straight-phase column with an isocratic HPLC technique. The fluorescence derivatives of the GCs, including the internal standard, were separated as clear single peaks and no interfering peaks were observed on the chromatograms. The lower limits of detection for F, E, PL and PN in plasma or urine were 0.1 ng/ml and those for 6beta-OHF and 6beta-OHP in plasma or urine were 0.5 ng/ml, at a signal-to-noise ratio of 3. The analytical recovery of known amounts of the GCs added to plasma or urine were almost 100%. This method can be applied to the determination of plasma or urinary F in renal transplant patients who received PL and can be applied for other metabolic investigations in relation to the change in blood pressure via 11beta-hydroxysteroid dehydrogenase or in hepatic metabolizing via CYP3A4.

Adult↗
PubMed1998

Structural and immunochemical characterization of beta-1,2-linked mannobiosyl phosphate residue in the cell wall mannan of Candida glabrata.

A mannan of Candida glabrata IFO 0622 digested by Arthrobacter exo-alpha-mannosidase and a beta-1,2-linked mannobiose obtained from the parent mannan by acid treatment was analyzed using 13C nuclear magnetic resonance spectroscopy. The results show that the beta-1, 2-linked mannobiosyl residue is esterified to a phosphate group through position C-1 in the alpha-configuration, Manbeta1- 2Manalpha1-HPO3-. The results of immunochemical assays of these mannans using the commercial antigenic factor sera of the genus Candida (Candida Check, Iatron) indicate that the main recognition site of serum no. 6 in this kit is the mannotetraosyl side-chain Manbeta1-2Manalpha1- 2Manalpha1-2Man in C. glabrata mannan and also suggest that the phosphate-containing unit (such as Manbeta1- 2Manalpha1-HPO3- in this mannan) behaves as one of the antigenic determinants of serum no. 6, but not of serum no. 5. Therefore, the present and previous findings indicate that serum no. 5 recognizes relatively longer beta-1,2-linked oligomannosyl side-chains, Manbeta1-[2Manbeta1-]n 2Man (n = 1-6), attached to the phosphate groups previously observed in the cell wall mannans of Candida albicans, Candida stellatoidea, and Candida tropicalis.

Agglutination↗
PubMed1998

Presence of Cu/Zn superoxide dismutase (SOD) immunoreactivity in neuronal hyaline inclusions in spinal cords from mice carrying a transgene for Gly93Ala mutant human Cu/Zn SOD.

This investigation deals with the immunocytochemical localization of Cu/Zn superoxide dismutase (SOD) in the spinal cord neurons of transgenic mice that overexpress Gly93Ala mutant human Cu/Zn SOD and demonstrate clinicopathological features similar to human amyotrophic lateral sclerosis (ALS) with Cu/Zn SOD mutation. At low magnification of light microscopy, the gray and white matter of the spinal cord of Gly93Ala mice showed more intense Cu/Zn SOD immunoreactivity than that of control mice. At higher magnification, the cytoplasm of control mice neurons displayed a distinct staining for Cu/Zn SOD, whereas the surrounding neuropil was only weakly stained. In contrast, the intensity of Cu/Zn SOD immunoreactivity in the cytoplasm of the majority of Gly93Ala mice neurons was similar to that in the neuropil. Almost all neuronal hyaline inclusions (NHIs) of Gly93Ala mice were positively immunostained by antibodies to Cu/Zn SOD, ubiquitin and phosphorylated neurofilament protein (NFP), the intensities of which were much higher in the NHIs than in the surrounding cytoplasm. In control mice, significant Cu/Zn SOD precipitation was not observed to be limited to any particular region of the neuronal cytoplasm. Intracytoplasmic vacuoles in the neuronal soma and processes of Gly93Ala mice were not stained by any of these antibodies. These results indicate that Cu/Zn SOD colocalizes with ubiquitin and phosphorylated NFP in NHIs of mice expressing mutant Cu/Zn SOD; similar findings have been shown for Lewy body-like inclusions of familial ALS patients with Cu/Zn SOD mutation. Moreover, our results point to the possibility that Cu/Zn SOD mutation may have a role in the abnormal Cu/Zn SOD accumulation in the NHIs, in association with motor neuron degeneration.

Animals↗