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S Chiba

Publications and source records attributed to S Chiba.

At least 73 records · Page 4Linked to original sources
PubMed2001

Carboxyl group of residue Asp647 as possible proton donor in catalytic reaction of alpha-glucosidase from Schizosaccharomyces pombe.

cDNA encoding Schizosaccharomyces pombe alpha-glucosidase was cloned from a library constructed from mRNA of the fission yeast, and expressed in Saccharomyces cerevisiae. The cDNA, 4176 bp in length, included a single ORF composed of 2910 bp encoding a polypeptide of 969 amino-acid residues with M(r) 106 138. The deduced amino-acid sequence showed a high homology to those of alpha-glucosidases from molds, plants and mammals. Therefore, the enzyme was categorized into the alpha-glucosidase family II. By site-directed mutagenesis, Asp481, Glu484 and Asp647 residues were confirmed to be essential in the catalytic reaction. The carboxyl group (-COOH) of the Asp647 residue was for the first time shown to be the most likely proton donor acting as the acid catalyst in the alpha-glucosidase of family II. Studies with the chemical modifier conduritol B epoxide suggested that the carboxylate group (-COO-) of the Asp481 residue was the catalytic nucleophile, although the role of the Glu484 residue remains obscure.

Amino Acid Sequence↗
PubMed2001

Existence of alpha(1A)- and alpha(1B)-adrenoceptor subtypes in canine mandibular alveolar arteries.

1. The present study attempted to pharmacologically characterize the alpha-adrenoceptor subtypes mediating vasoconstriction in canine isolated and perfused mandibular alveolar artery (MAA). 2. Noradrenaline (NA) and phenylephrine (PE) induced a strong vasoconstriction in a dose-dependent manner. The PE-induced vascular constriction was significantly inhibited by treatment with prazosin. Xylazine evoked a moderate vascular constriction and the xylazine-induced response was suppressed by rauwolscine. The NA-induced response was partially inhibited by rauwolscine and the remaining response to NA was abolished by subsequent administration of prazosin. 3. Treatment of MAA with WB4101 produced a dose-dependent inhibition of NA-induced vasoconstriction. Pretreatment of tissues with 10 micromol/L chloroethylclonidine produced a slight and statistically significant inhibition of NA-induced responses. BMY 7378, a selective alpha(1D)-adrenoceptor antagonist, failed to significantly affect vasoconstrictor responses to NA. 4. The present results suggests that: (i) both alpha(1)- and alpha(2)-adrenoceptors are involved in vasoconstrictor responses in the canine MAA; and (ii) the alpha(1)-adrenoceptors involved in the vasoconstrictor responses in the MAA are characterized as mainly of the alpha(1A)- and partially of the alpha(1B)-adrenoceptor subtype.

Adrenergic alpha-Agonists↗
PubMed2001

Tonsillectomy and steroid pulse therapy significantly impact on clinical remission in patients with IgA nephropathy.

We conducted a retrospective investigation of renal outcome in 329 patients with immunoglobulin A (IgA) nephropathy with an observation period longer than 36 months (82.3 +/- 38.2 months) in our renal unit between 1977 and 1995. Clinical remission, renal progression, and the impact of covariates were estimated by Kaplan-Meier analysis and a Cox regression model. In 157 of 329 patients (48%), disappearance of urinary abnormalities (clinical remission) was obtained. None of these 157 patients showed progressive deterioration, defined as a 50% increase in serum creatinine (Scr) level from baseline, during the observation period. Conversely, in patients without clinical remission, the Kaplan-Meier estimate of probability of progressive deterioration was 21% +/- 5% at 10 years. In the multivariate Cox regression model with 13 independent covariates, initial Scr level, histological score, tonsillectomy, and high-dose methylprednisolone therapy had a significant impact on clinical remission, whereas proteinuria, age, sex, levels of hematuria, blood pressure, conventional steroid therapy, angiotensin-converting enzyme inhibitor therapy, and cyclophosphamide therapy had no significant effect. These findings indicate that interventions aimed at achieving clinical remission have provided encouraging results applicable to managing patients with IgA nephropathy.

Adolescent↗
PubMed2001

Neonatal alloimmune thrombocytopenia due to anti-human leukocyte antigen antibody: a case report.

Anti-HLA antibodies reportedly exist in 31% of pregnant women. However, few ocurrences of neonatal alloimmune thrombocytopenia (NAIT) caused by anti-HLA antibody have been reported. In this study, maternal anti-HLA B60 and B61 antibodies were identified in patient serum at birth, but no anti-platelet antibodies were present. No maternal anti-HLA A2, A24, B51, or B52 antibodies were detected in patient serum. Platelet transfusion from the third donor was effective because these platelets expressed HLA A24 and B52 but not B60 or B61. Cross-matching tests between patient leukocytes or platelets and maternal serum were strongly positive, indicating that maternal anti-HLA antibodies were responsible for NAIT. This report is the first to demonstrate NAIT probably caused by maternal anti-HLA A24 and B52.

Female↗
PubMed2001

Pregnancy achieved following ICSI from a man with Klinefelter's syndrome and spinal cord injury.

Klinefelter's syndrome and spinal cord injury are major causes of male infertility. Intracytoplasmic sperm injection (ICSI) is a relatively new method of assisted reproduction. A testicular biopsy was obtained from a patient with the double complications of non-mosaic 47,XXY Klinefelter's syndrome and spinal cord damage, and motile spermatozoa were collected. ICSI was then performed. Of the four sperm-injected oocytes, three became fertilized and cleaved. Two embryos were implanted, resulting in a single pregnancy with visible evidence of a heartbeat appearing at 6 weeks gestation. The pregnancy is now entering its 20th week. To the best of our knowledge, this is the first case of a pregnancy resulting from the sperm of a patient with double complications.

Adult↗
PubMed2001

Successful unrelated cord blood transplantation in Philadelphia chromosome positive acute lymphoblastic leukemia during pulmonary aspergillosis treated by anti-fungal therapy, granulocyte colony-stimulating factor-mobilized granulocytes and surgical resection: case report.

A 3-year-old girl with Philadelphia chromosome positive acute lymphoblastic leukemia developed pulmonary aspergillosis during severe neutropenia by re-induction therapy. She was treated by intravenous fluconazole, oral itraconazole with plasma level monitoring and surgical resection of the focus for 3 months after clinical diagnosis of fungal infection was made. Once she had recovered from surgery we attempted to induce remission with anti-fungal treatment. She developed fever and neutropenia and appeared unlikely to remit with conventional chemotherapy. Unrelated one-antigen-mismatched cord blood (CB) transplantation was performed 2 months after the induction therapy. Her pulmonary aspergillosis was reactivated during subsequent conditioning. Anti-fungal drugs were switched to amphotericin B and granulocyte colony-stimulating factor-mobilized granulocyte concentrates were transfused. She obtained engraftment and has maintained complete hematological and molecular remission without signs of aspergillus infection for 13 months so far after transplantation. Even very high-risk transplantation in pediatric patients could be successfully supported by carefully designed intense comprehensive medical care.

Amphotericin B↗
PubMed2001

Oxidative damage is the earliest event in Alzheimer disease.

Recently, we demonstrated a significant increase of an oxidized nucleoside derived from RNA, 8-hydroxyguanosine (8OHG), and an oxidized amino acid, nitrotyrosine in vulnerable neurons of patients with Alzheimer disease (AD). To determine whether oxidative damage is an early- or end-stage event in the process of neurodegeneration in AD, we investigated the relationship between neuronal 8OHG and nitrotyrosine and histological and clinical variables, i.e. amyloid-beta (A beta) plaques and neurofibrillary tangles (NFT), as well as duration of dementia and apolipoprotein E (ApoE) genotype. Our findings show that oxidative damage is quantitatively greatest early in the disease and reduces with disease progression. Surprisingly, we found that increases in A beta deposition are associated with decreased oxidative damage. These relationships are more significant in ApoE epsilon4 carriers. Moreover, neurons with NFT show a 40%-56% decrease in relative 8OHG levels compared with neurons free of NFT. Our observations indicate that increased oxidative damage is an early event in AD that decreases with disease progression and lesion formation. These findings suggest that AD is associated with compensatory changes that reduce damage from reactive oxygen.

Aged↗
PubMed2001

Autonomic insufficiency as a factor contributing to dialysis-induced hypotension.

BACKGROUND: Autonomic insufficiency is considered a factor that contributes to dialysis-induced hypotension (DIH). However, the relationship between the two conditions has not been fully elucidated. METHODS: We investigated 44 haemodialysis patients using [(123)I]-meta-iodobenzylguanidine (MIBG) scintigraphy and power-spectral analysis (PSA) of heart rate variability. The patients were divided into four groups: a diabetic group with DIH, a diabetic group without DIH, a non-diabetic group with DIH, and a non-diabetic group without DIH. In these groups the heart to mediastinum average count rate (H/M), MIBG washout rate, and low- and high-frequency components of PSA were compared. RESULTS: From the [(123)I]-MIBG scintigraphy, for both early and delayed images, H/M of the groups with DIH were lower than in groups without DIH, in both diabetics and non-diabetics (P<0.05). For the early images, H/M of the diabetic groups were lower than in the non-diabetic groups, in the groups both with and without DIH (P<0.01). For the delayed images, H/M of the diabetic group was lower than in the non-diabetic group, in the groups with DIH (P<0.05). The MIBG washout rate was the highest in the diabetic group with DIH (P<0.05 vs diabetic and non-diabetic groups without DIH). The PSA of heart rate variability showed a good discrimination of the low-frequency component between the non-diabetic patients with and without DIH (P<0.05). Mean ultrafiltration volume and its rate were not different among the four groups. CONCLUSION: Autonomic insufficiency is more severe in patients with DIH than in those without, and its degree may be enhanced in diabetic patients. For the management of DIH, special care should be addressed not only to dry weight but also to autonomic insufficiency.

3-Iodobenzylguanidine↗
PubMed2001

Separate modulation of neuropeptide Y1 receptor on purinergic and on adrenergic neuroeffector transmission in canine splenic artery.

Our previous study demonstrated that the vasoconstrictor responses to trains of up to 10 pulses at 1 Hz of stimulation appeared to be purinergic monophasic, whereas a longer train of 30 pulses induced a biphasic vasoconstriction consisting of an initial, transient purinergic constriction followed by a prolonged adrenergic response. Neuropeptide Y (NPY) at doses of 0.01 and 0.1 microM produced a dose-dependent inhibition on the monophasic and biphasic vasoconstrictor responses to nerve stimulation. The treatment with Leu31 Pro34 neuropeptide Y (LP-NPY) (0.03 microM) did not affect the monophasic responses to short pulse trains of stimulation. However, LP-NPY markedly potentiated the second phase response to 30 pulse trains of stimulation, although it did not modify the first one. The LP-NPY-induced potentiation was abolished by BIBP 3226 (1 microM), a selective NPY Y1 receptor antagonist. The results indicate that the activation of NPY Y1 receptors may enhance the prolonged adrenergic vasoconstriction but not the transient purinergic response in the canine splenic artery.

Animals↗
PubMed2001

Clinical severity of Norwalk virus and Sapporo virus gastroenteritis in children in Hokkaido, Japan.

OBJECTIVE: To clarify the clinical significance and etiologic impact of Norwalk virus (NV) and Sapporo virus (SV) in viral gastroenteritis in Japanese children. STUDY DESIGN: Two outbreaks each of NV gastroenteritis and SV gastroenteritis occurring in an infant home in Sapporo, Japan, as well as 95 hospitalized children with acute gastroenteritis were retrospectively evaluated using a 0- to 20-point clinical severity scoring system. RESULTS: The mean severity scores for NV and SV gastroenteritis outbreaks were 7.9 and 5.2, respectively, as compared with 8.4 for rotavirus A gastroenteritis that occurred in the same infant home. Among 95 hospitalized children with acute gastroenteritis, rotavirus A was detected in 47% followed by NV in 18%. SV was not found. CONCLUSION: Our data indicate that NV can cause severe gastroenteritis and is an important etiologic agent in hospitalized cases, whereas SV causes mild gastroenteritis in Japanese children.

Acute Disease↗
PubMed2001

Steroid pulse therapy combined with tonsillectomy in IgA nephropathy associated with diabetes mellitus.

Ten patients with biopsy-confirmed IgA nephropathy associated with diabetes mellitus underwent dietary weight control and three courses of intravenous pulses of methylprenisolone followed by prednisolone for 6-12 months and tonsillectomy. The average length of the follow-up period was 47.8 (range 30-96) months. As compared with pretreatment values, hematuria, proteinuria, body mass index, and hemoglobin A(1c) were significantly improved after treatment. There were no significant differences with regard to blood pressure and glycemic blood glucose control. There was no worsening of diabetic retinopathy and nephropathy. During steroid pulse therapy, the patients who were treated with insulin needed a higher dosage of insulin; after steroid pulse therapy, the dosage returned to baseline. Even patients with IgA nephropathy and diabetes mellitus could be treated with combined therapy and showed beneficial responses, it they succeeded in reducing body mass index.

Adult↗
PubMed2001

Gene expression profiles in Ciona intestinalis tailbud embryos.

A set of 3423 expressed sequence tags derived from the Ciona intestinalis tailbud embryos was categorized into 1213 independent clusters. When compared with DNA Data Bank of Japan database, 502 clusters of them showed significant matches to reported proteins with distinct function, whereas 184 lacked sufficient information to be categorized (including reported proteins with undefined function) and 527 had no significant similarities to known proteins. Sequence similarity analyses of the 502 clusters in relation to the biosynthetic function, as well as the structure of the message population at this stage, demonstrated that 390 of them were associated with functions that many kinds of cells use, 85 with cell-cell communication and 27 with transcription factors and other gene regulatory proteins. All of the 1213 clusters were subjected to whole-mount in situ hybridization to analyze the gene expression profiles at this stage. A total of 387 clusters showed expression specific to a certain tissue or organ; 149 showed epidermis-specific expression; 34 were specific to the nervous system; 29 to endoderm; 112 to mesenchyme; 32 to notochord; and 31 to muscle. Many genes were also specifically expressed in multiple tissues. The study also highlighted characteristic gene expression profiles dependent on the tissues. In addition, several genes showed intriguing expression patterns that have not been reported previously; for example, four genes were expressed specifically in the nerve cord cells and one gene was expressed only in the posterior part of muscle cells. This study provides molecular markers for each of the tissues and/or organs that constitutes the Ciona tailbud embryo. The sequence information will also be used for further genome scientific approach to explore molecular mechanisms involved in the formation of one of the most primitive chordate body plans.

Animals↗
PubMed2001

Helical computer assisted tomography in pulmonary hypertension complicating left-to-right shunts--correlation with pulmonary hemodynamics.

The present study analyzed the helical computer-assisted tomography (CAT) findings in 30 patients with pulmonary hypertension (PH) associated with left-to-right shunts; specifically, ventricular septal defect, 23; atrioventricular septal defect, 6; patent ductus arteriosus, 1. Eight patients had 21 trisomy. Age ranged from 1 to 18 (mean, 4.1) months, and body weight ranged from 2.6 to 10.7 (mean, 4.9) kg. In all patients, the chest CAT revealed patchy areas of high and low attenuation (mosaic pattern) and regional atelectasis in the lung fields. The volume of low attenuated lesions and of atelectasis, and the total lung volume were derived from integration of areas measured on the CAT image. The ratios of low attenuated lesion/total lung volume (Lo), volume of atelectasis/ total lung volume (Ate) and low attenuated lesion and volume of atelectasis/total lung volume (Lo&Ate) were compared with hemodynamic parameters measured at cardiac catheterization. The pulmonary to systemic resistance ratio correlated with Lo (r=0.61, p<0.01) and Lo&Ate (r=0.69, p<0.01), whereas the pulmonary vascular resistance correlated with Ate (r=0.53, p<0.01). Lo, Ate and Lo&Ate in the chest CAT are reliable parameters that can be used to estimate pulmonary vascular resistance in patients with PH associated with left-to-right shunts.

Cardiac Catheterization↗
PubMed2001

[NPY as a periarterial sympathetic transmitter in isolated vessel].

Double-peaked vasoconstrictor responses to periarterial nerve electrical stimulation (PNS) were readily induced in the condition of 30-s trains of pulses in isolated, perfused canine splenic artery, using the cannula insertion technique. P2X purinoceptors have been shown to be involved mainly in the 1st peaked response and alpha 1 adrenoceptors mostly in the 2nd one. Administrated NPY induced no direct vasoconstriction or only a slight vasoconstriction, and it inhibited the double-peaked vasoconstriction in a dose-related manner. A small dose of NPY Y1-receptor agonist, L-P NPY, readily potentiated the 2nd peaked response to PNS, and an increasing dose of LP-NPY did both the 1st and 2nd peaked responses. The 2nd peaked response was significantly inhibited by treatment with chloroethylclonidine (CEC), an alpha 1B-adrenoceptor antagonist, but the 1st peaked response was not influenced. On the other hand, an alpha 1A-antagonist, WB4101, rather potentiated the 2nd peaked response, although it did not modify the 1st one. Administered NA-induced constrictions were consistently inhibited by WB4101 but not by CEC. From these results, it is concluded that NPY inhibits the release of ATP and NA from periarterial nerve terminals by activation of presynaptic NPY Y2 receptors, and it potentiates PNS-induced vasoconstrictions via alpha 1B-adrenoceptors by activation of postjunctional NPY Y1 receptors in the canine splenic artery.

Adenosine Triphosphate↗
PubMed2001

Dominant anti-vagal effect of pentobarbital on cardiac responses to intracardiac autonomic nerve stimulation in the dog.

The isolated canine atrium was perfused by heparinized blood of the donor dog. An adequate dose of pentobarbital that induced a potent hypotension in the donor did not produce any significant change in the atrial rate and developed tension in the isolated atrium perfused with donor's blood. Pentobarbital in doses that modified neither cardiac responses to intracardiac adrenergic nerve stimulation nor exogenously given norepinephrine or acetylcholine significantly inhibited intracardiac vagal responses. From these results, it is concluded that a large dose of pentobarbital has a dominant antivagal effect in the heart.

Animals↗
PubMed2001

Purification and substrate specificity of honeybee, Apis mellifera L., alpha-glucosidase III.

Alpha-glucosidase III, which was different in substrate specificity from honeybee alpha-glucosidases I and II, was purified as an electrophoretically homogeneous protein from honeybees, by salting-out chromatography, DEAE-cellulose, DEAE-Sepharose CL-6B, Bio-Gel P-150, and CM-Toyopearl 650M column chromatographies. The enzyme preparation was confirmed to be a monomeric protein and a glycoprotein containing about 7.4% of carbohydrate. The molecular weight was estimated to approximately 68,000, and the optimum pH was 5.5. The substrate specificity of alpha-glucosidase III was kinetically investigated. The enzyme did not show unusual kinetics, such as the allosteric behaviors observed in alpha-glucosidases I and II, which are monomeric proteins. The enzyme was characterized by the ability to rapidly hydrolyze sucrose, phenyl alpha-glucoside, maltose, and maltotriose, and by extremely high Km for substrates, compared with those of alpha-glucosidases I and II. Especially, maltotriose was hydrolyzed over 3 times as rapidly as maltose. However, maltooligosaccharides of four or more in the degree of polymerization were slowly degraded. The relative rates of the k0 values for maltose, sucrose, p-nitrophenyl alpha-glucoside and maltotriose were estimated to be 100, 527, 281 and 364, and the Km values for these substrates, 11, 30, 13, and 10 mM, respectively. The subsite affinities (Ai's) in the active site were tentatively evaluated from the rate parameters for maltooligosaccharides. In this enzyme, it was peculiar that the Ai value at subsite 3 was larger than that of subsite 1.

Animals↗
PubMed2001

Purification and identification of the essential ionizable groups of honeybee, Apis mellifera L., trehalase.

Trehalase (EC 3.2.1.28) of the bound type was purified as an electrophoretically homogeneous protein from adult honeybees by fractionation with ammonium sulfate, hydrophobic chromatography, and DEAE-Sepharose CL-6B, CM-Sepharose CL-6B, butyl-Toyopearl 650M, and p-aminophenyl beta-glucoside Sepharose 4B column chromatographies. The enzyme preparation was confirmed to be a monomeric protein containing 3.1% carbohydrate. The molecular weight was estimated to be approximately 69,000, and the optimum pH was 6.7. The Michaelis constant (Km) was 0.66 mM, and the molecular activity (k0) was 86.2 s(-1). The enzyme was an "inverting" type which produced beta-glucose from alpha, alpha-trehalose. Dependence of the V and Km values on pH gave values for the ionization constants, pKe1 and pKe2, of essential ionizable groups 1 and 2 of the free enzyme of 5.3 and 8.5, respectively. When the dielectric constant of the reaction mixture was decreased, pKe1, and pKe2 were shifted to higher values of + 0.2 and + 0.5 pH unit, respectively. The ionization heat (deltaH) of ionizable group 1 was estimated to be + 1.8 kcal/mol, and the deltaH value of group 2 was + 1.5 kcal/mol. These findings strongly support the notion that the essential ionizable groups of honeybee trehalase are two kinds of carboxyl groups, one being a dissociated type (-COO(-), ionizable group 1) and the other a protonated type (-COOH, ionizable group 2), although the pKe2 value is high.

Animals↗