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S Nagano

Publications and source records attributed to S Nagano.

At least 19 recordsLinked to original sources
PubMed1999

Benefit of a combined treatment with trientine and ascorbate in familial amyotrophic lateral sclerosis model mice.

We previously reported that the common toxic gain-of-function in various mutant copper-zinc superoxide dismutases (SOD1) seen in patients with familial amyotrophic lateral sclerosis (ALS) was an abnormal copper release from the enzyme protein. In this study, trientine and ascorbate, known to have a beneficial effect in an animal model of Wilson disease, were administered to transgenic mice overexpressing a mutated human SOD1 (G93A). The onset of neurological signs in the treated group was significantly delayed compared with that in the control group, and the time to reach total paralysis in the treated group was delayed as well. Since the agents used in this study cause low toxicity in animals and humans, this treatment may be a good candidate for clinical application.

Amyotrophic Lateral Sclerosis↗
PubMed1999

Putidaredoxin-cytochrome p450cam interaction. Spin state of the heme iron modulates putidaredoxin structure.

During the monooxygenase reaction catalyzed by cytochrome P450cam (P450cam), a ternary complex of P450cam, reduced putidaredoxin, and d-camphor is formed as an obligatory reaction intermediate. When ligands such as CO, NO, and O2 bind to the heme iron of P450cam in the intermediate complex, the EPR spectrum of reduced putidaredoxin with a characteristic signal at 346 millitesla at 77 K changed into a spectrum having a new signal at 348 millitesla. The experiment with O2 was carried out by employing a mutant P450cam with Asp251 --> Asn or Gly where the rate of electron transfer from putidaredoxin to oxyferrous P450cam is considerably reduced. Such a ligand-induced EPR spectral change of putidaredoxin was also shown in situ in Pseudomonas putida. Mutations introduced into the neighborhood of the iron-sulfur cluster of putidaredoxin revealed that a Ser44 --> Gly mutation mimicked the ligand-induced spectral change of putidaredoxin. Arg109 and Arg112, which are in the putative putidaredoxin binding site of P450cam, were essential for the spectral changes of putidaredoxin in the complex. These results indicate that a change in the P450cam active site that is the consequence of an altered spin state is transmitted to putidaredoxin within the ternary complex and produces a conformational change of the 2Fe-2S active center.

Amino Acid Substitution↗
PubMed1999

Myelin-associated oligodendrocytic basic protein is essential for normal arrangement of the radial component in central nervous system myelin.

We previously reported that myelin-associated oligodendrocytic basic protein (MOBP) was abundantly expressed in the central nervous system (CNS) myelin, and shared several characteristics with myelin basic protein (MBP). In particular, a cluster of positively charged amino acids was considered to facilitate compaction of the cytoplasmic face of the myelin sheath, as in the case of MBP. However, the contribution of MOBP in forming and maintaining the myelin sheath still remains unclear. Recent investigations showed that one isoform of MOBP was expressed in the embryo prior to myelination, and MOBP isoforms were colocalized with the microtubular network and nucleus in vitro. To explore the role of MOBP in vivo, we generated MOBP-deficient mice and analysed the CNS myelin. Surprisingly, the compact myelin was formed, however, the myelin from MOBP-deficient mice exposed to hexachlorophene, a known dysmyelinating agent, showed widening of the major dense lines. These results suggest that MOBP is not essential for myelin formation, but reinforces the apposition of the cytoplasmic faces of the myelin sheath. A striking phenotype of MOBP-deficient mice was the presence of the straight 'condensed' radial component. This component has been described as a tight junction-like complex running radially and zig-zag through the CNS myelin sheath between inner and outer mesaxons. These results suggest that MOBP is essential for normal arrangement of the radial component.

Animals↗
PubMed1999

Experimental His-bundle pacing: histopathological and electrophysiological examination.

His-bundle pacing gives a more physiological ventricular contraction in comparison to right ventricular apical pacing. However the problems of lead fixation and stability of long-term His-bundle pacing are yet unsolved. We used six adult beagles, in which a screw-in lead was anchored in the His-bundle region for observation of the pacing conditions and histopathologic changes of the conduction system over the course of 2 months. In the results, a satisfactory fixation was obtained using a conventional screw-in lead and no histological influence on the conduction system was observed. The pacing threshold at the time of implantation was 1.15 +/- 0.69 V (3.23 +/- 3.08 mA) in the pulse width of 0.5 ms. R wave amplitude, the impedance and slew rate were 7.28 +/- 2.04 mV, 409 +/- 102 Ohm, and 0.65 +/- 0.41 V/s, respectively. Two months later, these parameters changed to 2.83 +/- 1.06 V (10.4 +/- 5.71 mA), 5.63 +/- 1.62 mV, 310 +/- 71.3 Ohm, and 0.49 +/- 0.22 V/s, respectively. These results suggest the feasibility of clinical application of permanent His-bundle pacing.

Animals↗
PubMed1998

MAP kinase pathways as a route for regulatory mechanisms of IL-10 and IL-4 which inhibit COX-2 expression in human monocytes.

Mitogen-activated protein kinases (MAPKs) are activated by various extracellular stimuli and play an important role in regulating the expression of proinflammatory molecules in monocytes/macrophages. We first questioned whether MAPK activation in involved in cyclooxygenase (COX)-2 expression in lipopolysaccharide (LPS)-stimulated human monocytes. LPS induced the expression of COX-2 protein and COX-2 mRNA as well as the phosphorylation and activation of extracellular signal-regulated protein kinase (ERK)2 and p38 MAPK in monocytes. The induction of COX-2 mRNA, COX-2 protein, and prostaglandin (PG)E2 by LPS was inhibited by the specific inhibitors of ERK and p38 MAPK, suggesting that the activation of ERK2 and p38 MAPK is involved in COX-2 expression in LPS-stimulated monocytes. Since we previously showed that interleukin (IL)-10 and IL-4 similarly inhibited COX-2 expression in LPS-stimulated monocytes, we next questioned whether these cytokines regulate the phosphorylation and activation of ERK2 and p38 MAPK in LPS-stimulated monocytes. Interestingly, LPS-induced phosphorylation and activation of ERK2 was significantly inhibited by IL-4 and IL-10, while that of p38 MAPK was inhibited by IL-10, but not IL-4. These results suggest that the mechanisms of inhibition by IL-10 and IL-4 of the LPS-induced expression of proinflammatory molecules could be ascribed to the regulatory effects of both cytokines on MAPK activation.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

Retrospective study on the impact of hepatitis C virus infection on kidney transplant patients over 20 years.

BACKGROUND: The majority of chronic hepatitis is ascribable to hepatitis C virus (HCV) infection, whereas the clinical impact has not been understood in kidney transplant recipients. Our current study was carried out to assess the impact of HCV infection on kidney recipients over the long-term, and to investigate the effect and risk of interferon-alpha (IFN-alpha) therapy for chronic active hepatitis C. METHODS: Hepatitis B surface antigen (HBsAg) and antibody to HCV (HCVAb) were examined prospectively and retrospectively in 280 patients, who underwent kidney transplants in the period from 1973 to 1996. The patient survival rate, the graft survival rate, the incidence of liver dysfunction and the cause of mortality among the HCV infected and noninfected groups were analyzed. IFN-alpha therapy was performed on 10 patients with chronic active hepatitis C. RESULTS: Prevalence of the hepatitis virus was quite high at 34.3% (96/280): the frequency of the HBsAg carrier was 3.2% (9/280), that of the HCVAb carrier was 28.6% (80/280) and that of the both carriers was 2.5% (7/280). The other 184 cases (65.7%) were negative for both HBsAg and HCVAb. Liver dysfunction developed at the significantly higher incidence of 55% in HCVAb carriers compared to the 9.2% of the noninfected group (P<0.01). HCVAb carriers had a poor survival rate in the second decade compared to the noninfected group: 83.7% vs. 88.91% for 10-year survival (P=0.44) and 63.9% vs. 87.9% for 20-year survival (P<0.05). The poor survival rate was a result of the mortality from liver disorder. Five patients died of such disease in the infected groups whereas no noninfected patient died in the same period (p<0.01). As the result of IFN-alpha therapy, biochemical activity normalized or improved in eight cases, whereas the HCV-RNA titer was reduced only in three patients. Only one patient maintained normal biochemical markers and undetectable levels of HCV-RNA for 2 years after treatment. The therapy was discontinued for five patients with the adverse effects of acute rejection, deterioration of diabetes, and depression. CONCLUSIONS: HCV infection has a significant impact on kidney transplant recipients over the long term and in particular affects them in the second decade. Our pilot study revealed only partial efficacy of IFN-alpha therapy for HCV-infected recipients, but with the high risk of acute rejection.

Adult↗
PubMed1998

Expression and processing of recombinant human galactosylceramidase.

Stable transformants of CHO cells that overexpress human galactosylceramidase (GALC) were established. The GALC within the cell consisted of 50- and 30-kDa proteins. The active GALC secreted into the culture medium in large amounts consisted of the 80-kDa precursor enzyme. We confirmed that the precursor enzyme was taken up by fibroblasts via the mannose-6-phosphate receptor and processed into the 50- and 30-kDa fragments. Fragmentation was inhibited by the lysosomotropic agents chloroquine and NH4Cl, suggesting that it occurs within the lysosome. GALC mutations identified in globoid cell leukodystrophy suppressed fragmentation. Neither the 50- or 30-kDa fragment expressed had GALC activity, indicative that the entire structure is necessary for enzyme activity and that fragments expressed separately cannot associate to form the active enzyme.

Animals↗
PubMed1998

A 20-year case study of a kidney transplant recipient with chronic active hepatitis C: clinical course and successful treatment for late acute rejection induced by interferon therapy.

BACKGROUND: The influence of hepatitis C virus (HCV) infection has been discussed in kidney transplantation. Our case study focused on four points: the clinical course of an HCV-infected recipient; the pathogenesis of hepatic disorders in such a patient; interferon (IFN)-alpha therapy; and the risk of IFN-alpha therapy. METHOD: A patient was suspected of acquiring HCV via transfusion at kidney transplant. He was examined several times serologically, virologically, endoscopically, and pathologically during a 20-year follow-up. RESULTS: Abnormal biochemical markers were found within a month after transplantation but recovery occurred without any treatment. Within 3 years postoperatively, hepatic disorder developed including peliosis hepatis, nodular regenerative hyperplasia, and cholestasis. These pathological conditions were ascribed to immunosuppressants: cyclophosphamide and azathioprine. Abnormal chemical markers decreased to normal values for 4 consecutive years with the substitution of cyclophosphamide and azathioprine for mizoribine. During the subsequent 13 years, the patient developed chronic hepatitis with clinical and morphological features of hepatitis C infection. Anti-HCV antibody was positive from the second post-transplant year and HCV genome was detected in the 17th year. IFN-alpha therapy was initiated in the 17th year and resulted in normal transaminase activities with no effect on viremia. However, acute cellular rejection developed. The rejection was steroid resistant but responsive to OKT3. CONCLUSION: HCV might remain latent for approximately 7 years even in kidney recipients unless toxic hepatitis occurs. Hepatotoxic drugs may cause a wide spectrum of liver diseases in HCV carriers as a result of the overload of immunosuppressants on hepatocytes. IFN-alpha could induce acute cellular rejection even in the 17th year. Such acute rejection can be reversible with OKT3.

Adult↗
PubMed1998

Malignant neoplasm in kidney transplantation.

BACKGROUND: The kidney recipient is at a higher risk for cancer than is the general population, although the incidence of neoplasms in general is considered lower in Japan than in Western countries. The cause of this increased risk associated with either transplantation or geography has not yet been established. METHOD: The incidences and sites of malignant neoplasms were analyzed in 285 kidney recipients, who had been followed up for 3007 patient-years. The relationship between immunosuppressive states, the numbers of CD4-positive T lymphocytes, and the presence of malignant neoplasms was studied retrospectively. RESULTS: Eighteen malignant neoplasms were found in 17 of the 285 patients (6%). The malignancies developed in these patients an average of++ 1 26.5 months after transplantation. The incidence was only 3.9% at 10 years, increasing to 13.9% at 20 years. No difference in the time-course incidence was found between azathioprine-based and cyclosporin-based immunosuppressive regimens. The malignancies developed in the digestive organs in more than half of the patients, and were mainly in the liver, colon and rectum, and stomach, with a relatively low incidence of skin cancer and lymphoma. There was only one case of Epstein-Barr virus genome found in 5 specimens that were tested. Concerning the immunosuppressive state, CD4-positive T lymphocyte counts were not related directly with malignancies in our series. CONCLUSION: The cumulative incidence of malignancy increased markedly in the second posttransplant decade. The site of cancers in kidney recipients mirrors that of general Japanese malignancies. Our results revealed neither the cause nor predictor for malignancies in kidney transplant patients.

Adolescent↗
PubMed1998

Clinical and histopathologic examination of renal allografts treated with tacrolimus (FK506) for at least one year.

BACKGROUND: We clinically and pathologically analyzed renal allografts from 1 9 renal transplant patients treated with tacrolimus (FK506) for more than 1 year. METHODS: Twenty-six renal allograft biopsy specimens from 1 9 renal transplant patients who underwent transplantations between 1991 and 1993 were evaluated. Thirteen biopsies were performed from stable functioning renal allografts with informed consent (nonepisode biopsy) and the other 13 were from dysfunctional renal allografts with a clinical indication for biopsy (episode biopsy). RESULTS: The main pathologic diagnoses (some overlap) were acute rejection (AR; n = 4), chronic rejection (CR; n=5), AR+CR (n =4), recurrent IgA nephropathy (n =5), normal findings (n =2), minimal-type chronic FK506 nephropathy (n = 9), and mild-type FK506 nephropathy (n = 11). Of the nonepisode biopsies, 7 and 4 biopsies showed minimal-type and mild-type chronic FK506 nephropathy, respectively. Chronic FK506 nephropathy consisted of rough and foamy tubular vacuolization (5 biopsies), arteriolopathy (angiodegeneration of the arteriolar wall; 20 biopsies), focal segmental glomerulosclerosis (4 biopsies) and the striped form of interstitial fibrosis (11 biopsies). The serum creatinine levels of patients in the mild-type chronic FK506 nephropathy group, which included 7 episode biopsies, were statistically higher than those in the minimum-type chronic FK506-nephropathy group (P< 0.001). CONCLUSIONS: This study demonstrates that chronic FK506 nephropathy consists primarily of arteriolopathy manifesting as insudative hyalinosis of the arteriolar wall, and suggests that mild-type chronic FK506 nephropathy is a condition which may lead to deterioration of renal allograft function.

Adult↗
PubMed1998

[A case of lymphocytic interstitial pneumonia].

A 56-year-old female was admitted on November 1995 to our hospital because of the abnormal shadow on her chest X-ray. Although the chest X ray film revealed diffuse reticulonodular shadows in the bilateral lung fields and right hilar lymphadenopathy, she had not any complaints. Furthermore, mediastinal lymphadenopathy and polyclonal hypergammaglobulinemia were noted. For a further examination, transcutaneous thoracoscopic lung biopsy was performed on August 1996. The lung specimens showed a interstitial infiltration of small lymphocytes exclusively around bronchioles. And the diagnosis of lymphocytic interstitial pneumonia (LIP) was made. She had been suffered from bronchial asthma for 27 years. This is the first report of LIP accompanied with bronchial asthma. Its relationship between LIP and bronchial asthma remains unclear. In the 2 years of follow-up, she remained asymptomatic with unchanged chest radiogram. And her pulmonary function was preserved for the 2 years. But lymphocytic interstitial pneumonia may induce malignant lymphoproliferative disease potentially, we should carefully follow up.

Asthma↗
PubMed1997

Hydrogen bond network in the distal site of peroxidases: spectroscopic properties of Asn70 --> Asp horseradish peroxidase mutant.

The distal His in peroxidases forms a hydrogen bond with the adjacent Asn, which is highly conserved among many plant and fungal peroxidases. Our previous work [Nagano, S., Tanaka, M., Ishimori, K., Watanabe, Y., & Morishima, I. (1996) Biochemistry 35, 14251-14258] has revealed that the replacement of Asn70 in horseradish peroxidase C (HRP) by Val (N70V) and Asp (N70D) discourages the oxidation activity for guaiacol, and the elementary reaction rate constants for the mutants was decreased by 10-15-fold. In order to delineate the structure-function relationship of the His-Asn couple in peroxidase activity, heme environmental structures of the HRP mutant, N70D, were investigated by CD, 1H NMR, and IR spectroscopies as well as Fe2+/Fe3+ redox potential measurements. While N70D mutant exhibited quite similar CD spectra and redox potential to those of native enzyme, the paramagnetic NMR spectrum clearly showed that the hydrogen bond between the distal His and Asp70 is not formed in the mutant. The disappearance of the splitting in the 1H NMR signal of heme peripheral 8-methyl group observed in 50% H2O/50% D2O solution of N70D-CN suggests that the hydrogen bond between the distal His and heme-bound cyanide is also disrupted by the mutation, which was supported by the low C-N vibration frequency and large dissociation constant of the heme-bound cyanide in the mutant. Together with the results from various spectroscopies and redox potentials, we can conclude that the improper positioning of the distal His induced the cleavages of the hydrogen bonds around the distal His, resulting in the substantial decrease of the catalytic activity without large structural alterations of the enzyme. The His-Asn hydrogen bond in the distal site of peroxidases, therefore, is essential for the catalytic activity by controlling the precise location of the distal His.

Asparagine↗
PubMed1997

Adult onset globoid cell leukodystrophy (Krabbe disease): analysis of galactosylceramidase cDNA from four Japanese patients.

We examined galactosylceramidase (GALC) cDNA in four Japanese patients with adult onset globoid cell leukodystrophy (Krabbe disease; AO-GLD) by polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis, subsequent sequence determination, and restriction enzyme digestion of PCR products, initial symptoms were the onset of slowly progressive spastic paraplegia from the middle of the second decade, and all patients had diminished GALC activity in their leukocytes. We identified three missense mutations (I66M, G270D, L618S) and one exon-6 skipping (535-573del). Two of the patients had only the I66M mutant mRNA, and one only the G27OD mutant mRNA. The fourth patient carried a compound heterozygous mutation of 535-573del and L618S. To determine the enzymatic activities produced by these mutations, we constructed mutated GALC cDNAs and expressed them in COS-1 cells. Three mutations, viz., G270D, L618S, and exon-6 skipping (535-573del), produced diminished GALC activity as expected. The I66M mutation in the wild-type GALC cDNA(I289) had normal activity, but when this mutation and the V289 polymorphism were introduced into the same allele, it had decreased activity. Thus, the combination of a unique mutation and polymorphism causes conformational change in the GALC enzyme, resulting in low enzymatic activity. AO-GLD mutations, including those found here, are located in the N-terminus (I66M, G270D, 535-573del) or C-terminus (L618S) of the GALC enzyme, whereas the reported mutations in the infantile form (IF-GLD) are in the central domain. This difference in mutation sites may affect the clinical features of GLD.

Adult↗
PubMed1997

Albuminuria is directly associated with increased plasma PAI-1 and factor VII levels in NIDDM patients.

Increased plasma plasminogen activator inhibitor type 1 (PAI-1), coagulation factor VII (FVII) and fibrinogen levels have been recognized as risk factors for cardiovascular disease. Because a substantially high incidence of cardiovascular disease has been reported in diabetic patients with nephropathy compared with those without nephropathy, we measured plasma levels of PAI-1, FVII activity and fibrinogen in non-insulin-dependent diabetic patients (NIDDM) with normoalbuminuria (without nephropathy), microalbuminuria (incipient nephropathy) and macroalbuminuria (overt nephropathy). PAI-1 and FVII levels were significantly increased in NIDDM with overt nephropathy compared with NIDDM without nephropathy. Fibrinogen levels were comparable between the patients with normo-, micro- and macro-albuminuria. Univariate regression analysis indicated that PAI-1 and FVII levels were significantly correlated with the albumin excretion rate (AER) in urine. PAI-1, FVII and fibrinogen levels were significantly correlated with the degree of insulin resistance estimated by the steady state plasma glucose concentration (SSPG) during the continuous infusion of glucose, insulin and octreotide. PAI-1 levels were correlated with plasma triglyceride (TG) levels. Multiple regression analysis revealed that AER was significantly associated with PAI-1 and FVII levels, whereas TG lost significant correlation with PAI-1 when AER, SSPG and plasma TG were entered as independent variables. SSPG retained an independent correlation with fibrinogen, PAI-1 and FVII levels. These results suggest that elevated plasma levels of PAI-1 and FVII in NIDDM patients with nephropathy are directly associated with renal damage, whereas insulin resistance widely regulates hemostatic components in NIDDM patients, irrespective of the presence of nephropathy.

Albuminuria↗
PubMed1997

Chronic inflammatory demyelinating polyneuropathy accompanied by hepatocellular carcinoma.

We report a patient with chronic inflammatory demyelinating polyneuropathy (CIDP) accompanied by hepatocellular carcinoma (HCC). Due to the remarkable weakness in the lower limbs and loss of the position sense, he could not walk. On neurophysiological examination, he had impaired nerve conduction velocities. Biopsied nerve and muscle specimens demonstrated demyelination of nerve fibers and neurogenic degeneration of muscles. After steroid therapy he showed marked improvement in muscle strength and sensory function.

Anti-Inflammatory Agents↗