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Biomedical subjects

I Sakuma

Publications and source records attributed to I Sakuma.

At least 55 records · Page 3Linked to original sources
PubMed1998

Enzyme therapy in Gaucher disease type 2: an autopsy case.

A Japanese patient with Gaucher disease type 2 was treated with enzyme therapy, alglucerase, from 7 to 22 months of age. Whereas hematologic parameters were normalized and hepatosplenomegaly was alleviated, no improvement in neurologic symptoms occurred, and the patient died of respiratory failure at age 22 months. Postmortem examination revealed massive intra-alveolar infiltration of Gaucher cells in lungs and in the central nervous system, i.e., the presence of Gaucher cells in the perivascular Virchow-Robins spaces in the cortex and deep white matter and extensive lamilar necrosis with reactive proliferation of blood vessels and macrophage infiltration of the cerebral cortex. It is suggested that enzyme therapy, with thus far recommended dose, does not prevent long-term respiratory and central nervous system involvement in severe varients of Gaucher disease.

Brain↗
PubMed1998

bcl-6 protein is identified in high-grade but not low-grade mucosa-associated lymphoid tissue lymphomas of the stomach.

The pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma is an intriguing issue and is thought to be closely related to Helicobacter pylori infection. Gastric MALT lymphoma is thought to progress from the reactive state to low-grade malignancy and sometimes to high-grade malignancy. In the present study, we examined immunohistochemically the expression of bcl-6 and p53 proteins in gastric MALT and gastric diffuse large lymphoma without low-grade MALT lymphoma component (gastric DLL) to elucidate their role in high-grade transformation of low-grade MALT lymphoma. We detected bcl-6 protein only in the high-grade components in four of eight high-grade MALT lymphoma cases and in four of six gastric DLL cases. In contrast, none of 17 cases of low-grade MALT lymphoma expressed bcl-6 protein (P < .05). p53 protein was detected in the high-grade components in 6 of 8 high-grade MALT lymphoma cases and in 4 of 6 gastric DLL cases, but it was expressed in 2 of 17 cases of low-grade MALT lymphomas. All high-grade gastric MALT lymphomas cases were positive for p53 protein and/or bcl-6 protein. There is a tendency for an inverse relationship between bcl-6 protein and p53 protein. These findings suggest that high-grade transformation of gastric low-grade MALT lymphoma is associated with overexpression of p53 or bcl-6 protein.

Adult↗
PubMed1997

Expression of Fas ligand mRNA in germinal centres of the human tonsil.

Fas ligand (FasL), a cell surface molecule belonging to the tumour necrosis family, induces apoptosis through its receptor, Fas antigen (Fas). Germinal centre B cells strongly express Fas, but the role of the Fas-FasL system in B-cell selection in the germinal centre remains unclear. In the present study, FasL mRNA in the tonsils was examined by RNA in situ hybridization. FasL mRNA was detected in the lymphocytes of both germinal centres and interfollicular areas, but much more intensively in the former. The distribution of cells strongly expressing FasL mRNA in the germinal centres was quite similar to that of CD45RO-positive T cells. Immunohistochemically, however, most of the germinal centre cells were positive for FasL. Flow cytometric analysis demonstrated that FasL-positive cells of the tonsils included not only CD3-positive/CD45RO-positive T cells, but also CD19-positive B cells. This finding therefore suggests either that germinal centre B cells can produce FasL, although the level of mRNA was equivocal, or that the soluble form of FasL may be released from FasL-positive T cells in the germinal centres and then bind to Fas-positive germinal centre B cells. Thus, the Fas-FasL system may participate in the positive selection of B cells.

Antigens, Surface↗
PubMed1997

Analysis of genotypes and amino acid residues 2209 to 2248 of the NS5A region of hepatitis C virus in relation to the response to interferon-beta therapy.

In chronic hepatitis C virus (HCV) infection, genotypes other than genotype 1b of HCV (HCV-1b) and low serum HCV-RNA levels are known to be associated with favorable outcome of interferon alfa (IFN-alpha) therapy. In addition, we recently reported a close correlation between the number of mutations in amino acid sequences 2209 to 2248 of the nonstructual protein 5A gene (NS5A2209-2248) of HCV-1b and the response to IFN-alpha. In the present study, we analyzed these viral factors in relation to the efficacy to IFN-beta, another type I IFN. The pretreatment sera of 40 patients treated with IFN-beta intravenously at 6 MU daily for 42 days were studied. HCV genotypes, serum HCV-RNA levels, and the amino acid sequence of NS5A2209-2248 in HCV-1b were determined. A sustained complete response to IFN therapy occurred in none of the ten patients with the wild-type HCV-1b who had an NS5A2209-2248 sequence identical to the prototype HCV-1b and in none of the six patients with the intermediate-type HCV-1b that had 1 mutation. In contrast, complete responses occurred in the following: 4 of 6 patients with the mutant-type HCV-1b that had five to ten mutations; 6 of 13 patients with genotype 2a of HCV (HCV-2a); and 2 of 5 patients with genotype 2b of HCV (HCV-2b). Among patients with the mutant-type HCV-1b or genotype 2 of HCV (HCV-2) the rate of complete response was significantly higher (12 of 24 vs. 0 of 16 patients, P < .001) and HCV-RNA levels were significantly lower (4.5 [4.0-6.5] vs. 6 [4.5-6.5] log copies/mL, median [range]; P < .001) compared with patients with the wild- or the intermediate-type HCV-1b. Patients with the mutant-type HCV-1b or HCV-2 whose HCV-RNA levels were lower than 6 log copies/mL had a complete response rate of 75% (12 of 16 patients) in contrast to 0% (0 of 24 patients) of the others (P < .001). These results indicate that the mutant-type HCV-1b or HCV-2 are sensitive to IFN-beta as well as IFN-alpha. In conclusion, the determination of HCV genotypes, NS5A2209-2248 of HCV-1b and serum HCV-RNA levels may facilitate the selection of patients with a high likelihood of response to IFN-beta.

Amino Acid Sequence↗
PubMed1997

Agonist-independent tonic inhibitory influence of Gi on adenylate cyclase activity in rabbit ventricular myocardium and its removal by pertussis toxin: a role of empty receptor-mediated Gi activation.

We evaluated whether Gi has a tonic inhibitory influence on myocardial adenylate cyclase (AC) in an agonist-independent way, and, if so, whether this is attributable to substantial coupling between agonist-free, empty inhibitory receptors and G. Rabbits received pertussis toxin (PTX, 10 micrograms/kg i.v.) 40 h before preparing ventricular myocardial membranes, which was associated with virtually complete in vivo ADP-ribosylation and inactivation of the 41-kDa substrate. Pretreatment with PTX had no influence on basal AC activity but significantly enhanced AC activity elicited by 100 microM GTP. Furthermore, it markedly increased AC activity stimulated with 5'-guanylyl imidodiphosphate (GppNHp) and isoproterenol through a wide range of concentrations of these stimulants. These findings indicate that Gi has a tonic influence on he stimulatory effects of guanine nucleotides and beta-adrenoceptor stimulation on AC even in the absence of the inhibitory receptor agonists. The muscarinic receptor antagonists atropine and AF-DX 116 significantly enhanced isoproterenol-stimulated AC activity, as PTX pretreatment did, except that statistically significant increasing effects of these antagonists on GppNHp-stimulated AC activity was observed only at higher concentrations of GppNHp. The enhancement by atropine was not detected in PTX-pretreated membranes. The selective beta 2-adrenoceptor antagonist ICI 118,551 did not modify the stimulatory effects of guanine nucleotides and isoproterenol on AC in either control or PTX-pretreated membranes, excluding the possible involvement of beta 2-adrenoceptors in tonic activation of Gi. We conclude that Gi is tonically activated by agonist-free, empty muscarinic receptors, which leads to attenuation of Gs-mediated or beta-adrenoceptor-mediated activation of AC. The potentiating effect of PTX pretreatment on GppNHp-stimulated AC activity may be at least partially due to the direct action of PTX on the Gi heterotrimeric complex, independently of the coupled receptors.

Adenosine Diphosphate↗
PubMed1997

Anti-CD53 monoclonal antibody induced LFA-1/ICAM-1-dependent and -independent lymphocyte homotypic cell aggregation.

CD53 is a pan-leukocyte glycoprotein and belongs to a member of the tetraspan family of cell membrane proteins. The predicted structure and functional characteristics of CD53 suggest that it may play important roles in transmembrane signaling, but its roles in cell adhesion have not been clarified. The present study shows that anti-CD53 monoclonal antibody (mAb), HI29 induced homotypic cell aggregation of lymphoid cell lines including a B cell line from a patient with leukocyte adhesion deficiency syndrome (LAD). The homotypic cell aggregation was blocked by another anti-CD53 mAb, MEM53, in all the examined cell lines and by anti-LFA-1 (CD11a/CD18) or anti-ICAM-1 (CD54) mAbs in the cell lines except for the LAD line, but it was not blocked by anti-CD44 or anti-CD49d mAb. The induced homotypic cell aggregation was energy-dependent. These findings suggest that CD53 relates to LFA-1/ICAM-1-dependent and -independent pathways of homotypic cell aggregation of lymphocytes and that it plays an important role in lymphocyte activation and cell adhesion.

Antibodies, Blocking↗
PubMed1997

Evidence against a role of cytochrome P450-derived arachidonic acid metabolites in endothelium-dependent hyperpolarization by acetylcholine in rat isolated mesenteric artery.

1. In rat mesenteric artery, acetylcholine (ACh) causes endothelium-dependent hyperpolarization by releasing endothelium-derived hyperpolarizing factor (EDHF). Recent evidence suggests that EDHF may be a cytochrome P450-derived arachidonic acid metabolite. The aim of the present study was to investigate whether such a metabolite is indeed contributing to ACh-induced hyperpolarization observed in rat mesenteric artery. 2. The phospholipase A2 inhibitor quinacrine (30 microM) nearly completely eliminated ACh-induced hyperpolarization. However, the hyperpolarizing effect of pinacidil was also abolished in the presence of quinacrine. 3. The imidazole antimycotic agents ketoconazole (50 microM), clotrimazole (30 microM) and miconazole (10 microM), which bind to the heme moiety of cytochrome P450, eliminated not only ACh-induced hyperpolarizations but also those induced by pinacidil. SKF525A (30 microM), a prototype inhibitor of the enzyme, also abolished the hyperpolarizing responses to both agents. In contrast, neither 17-octadecynoic acid (10 microM), a mechanism-based inhibitor of cytochrome P450 metabolism of fatty acids, nor eicosatetraynoic acid (20 microM), an inhibitor of all arachidonic acid metabolic pathways, altered ACh-induced hyperpolarization. Furthermore, the hyperpolarization was unaffected by the preferential inhibitors of specific cytochrome P450 isozymes, alpha-naphtoflavone (1 microM), diedthyldithiocarbamate (50 microM), metyrapone (20 microM) and troleandomycin (10 microM). 4. Pretreatment of rats with lipopolysaccharide (2 mg kg-1) and exposure to nitroprusside (10 microM), both of which are expected to inhibit cytochrome P450 activity due to nitric oxide overproduction, were without effect on ACh-induced hyperpolarization. Pretreatment of rats for 3 days with pentobarbitone (80 mg kg-1 day-1), a cytochrome P450 inducer, also did not affect the hyperpolarizing response to ACh. 5. Arachidonic acid in concentrations up to 100 microM had no detectable effect on smooth muscle membrane potential. 11, 12-Epoxyeicosatrienoic acid (EET, 10 microM), one of cytochrome P450-derived epoxygenase metabolites of arachidonic acid, elicited a small endothelium-independent membrane hyperpolarization. The hyperpolarizing response to EET was blocked by glibenclamide (30 microM), in contrast to the response to ACh. 6. These results suggest that the contribution of a cytochrome P450-derived metabolite of arachidonic acid to ACh-induced hyperpolarization via EDHF release is minimal or absent in rat mesenteric artery.

Acetylcholine↗
PubMed1997

Sources of Ca2+ in relation to generation of acetylcholine-induced endothelium-dependent hyperpolarization in rat mesenteric artery.

1. The aim of the present study was to identify the sources of Ca2+ contributing to acetylcholine (ACh)-induced release of endothelium-derived hyperpolarizing factor (EDHF) from endothelial cells of rat mesenteric artery and to assess the pathway involved. The changes in membrane potentials of smooth muscles by ACh measured with the microelectrode technique were evaluated as a marker for EDHF release. 2. ACh elicited membrane hyperpolarization of smooth muscle cells in an endothelium-dependent manner. The hyperpolarizing response was not affected by treatment with 10 microM indomethacin, 300 microM NG-nitro-L-arginine or 10 microM oxyhaemoglobin, thereby indicating that the hyperpolarization is not mediated by prostanoids or nitric oxide but is presumably by EDHF. 3. In the presence of extracellular Ca2+, 1 microM ACh generated a hyperpolarization composed of the transient and sustained components. By contrast, in Ca(2+)-free medium, ACh produced only transient hyperpolarization. 4. Pretreatment with 100 nM thapsigargin and 3 microM cyclopiazonic acid, endoplasmic reticulum Ca(2+)-ATPase inhibitors, completely abolished ACh-induced hyperpolarization. Pretreatment with 20 mM caffeine also markedly attenuated ACh-induced hyperpolarization. However, the overall pattern and peak amplitude of hyperpolarization were unaffected by pretreatment with 1 microM ryanodine. 5. In the presence of 5 mM Ni2+ or 3 mM Mn2+, the hyperpolarizing response to ACh was transient, and the sustained component of hyperpolarization was not observed. On the other hand, 1 microM nifedipine had no effect on ACh-induced hyperpolarization. 6. ACh-induced hyperpolarization was nearly completely eliminated by 500 nM U-73122 or 200 microM 2-nitro-4-carboxyphenyl-N, N-diphenylcarbamate, inhibitors of phospholipase C, but was unchanged by 500 nM U-73343, an inactive form of U-73122. Pretreatment with 20 nM staurosporine, an inhibitor of protein kinase C, did not modify ACh-induced hyperpolarization. 7. These results indicate that the ACh-induced release of EDHF from endothelial cells of rat mesenteric artery is possibly initiated by Ca2+ release from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ pool as a consequence of stimulation of phospholipid hydrolysis due to phospholipase C activation, and maintained by Ca2+ influx via a Ni(2+)- and Mn(2+)-sensitive pathway distinct from L-type Ca2+ channels. The Ca(2+)-influx mechanism seems to be activated following IP3-induced depletion of the pool.

Acetylcholine↗
PubMed1997

Alterations in endothelium-dependent hyperpolarization and relaxation in mesenteric arteries from streptozotocin-induced diabetic rats.

1. The aim of this study was to determine whether endothelium-dependent hyperpolarization and relaxation are altered during experimental diabetes mellitus. Membrane potentials were recorded in mesenteric arteries from rats with streptozotocin-induced diabetes and age-matched controls. The resting membrane potentials were not significantly different between control and diabetic mesenteric arteries (-55.3 +/- 0.5 vs -55.6 +/- 0.4 mV). However, endothelium-dependent hyperpolarization produced by acetylcholine (ACh; 10(-8)-10(-5) M) was significantly diminished in amplitude in diabetic arteries compared with that in controls (maximum -10.4 +/- 1.1 vs -17.2 +/- 0.8mV). Furthermore, the hyperpolarizing responses of diabetic arteries were more transient. 2. ACh-induced hyperpolarization observed in control and diabetic arteries remained unaltered even after treatment with 3 x 10(-4) M N(G)-nitro-L-arginine (L-NOARG), 10(-5) M indomethacin or 60 u ml (-1) superoxide dismutase. 3. Endothelium-dependent hyperpolarization with 10(-6) M A23187, a calcium ionophore, was also decreased in diabetic arteries compared to controls (-8.3 +/- 1.4 vs -18.0 +/- 1.9 mV). However, endothelium-independent hyperpolarizing responses to 10(-6) M pinacidil, a potassium channel opener, were similar in control and diabetic arteries (-20.0 +/- 1.4 vs - 19.2 +/- 1.1 mV). 4. The altered endothelium-dependent hyperpolarizations in diabetic arteries were almost completely prevented by insulin therapy. Endothelium-dependent relaxations by ACh in the presence of l0(-4) M L-NOARG and 10(-5) M indomethacin in diabetic arteries were also reduced and more transient compared to controls. 5. These data indicate that endothelium-dependent hyperpolarization is reduced by diabetes, and this would, in part, account for the impaired endothelium-dependent relaxations in mesenteric arteries from diabetic rats.

Acetylcholine↗
PubMed1997

[New combination therapy with FTM [5-FU, pirarubicin (THP) and MMC] for treatment of inoperable advanced gastric cancer].

Clinical usefulness of a new combination FTM therapy consisting of 5-FU, Pirarubicin (THP) and MMC for the treatment of advanced gastric cancers was investigated. 5-FU, THP or MMC was administered at a dose of 600 mg/m2 on day 1, 8, 22 and 29, 30 mg/m2 on days 1 and 22, and 10 mg/m2 on day one only of each course, respectively. Eighteen patients with inoperable advanced gastric cancer were treated with FTM. All drugs were investigated by intravenously by one shot. The tumor response rate was 50% [9 of 18 showed PR]. The survival rate was higher in responders than in nonresponders (18.1% vs 11.1%) (p < 0.05). Side effects in the gastrointestinal tract were minimal. Cardiotoxicity and nephrotoxicity were not detected, but myelosuppression was prominent in most cases. G-CSF was given in sixteen patients (88%), and platelet transfusion was performed in two patients (11%). New combination FTM therapy is an effective treatment regimen even for advanced inoperable gastric cancer.

Adult↗
PubMed1997

Role of QT interval prolongation in the creation of spiral wave type reentry.

The inducibility of reentry was compared for four QT patterns in a heart conduction simulation model. Local (L) and gradual (G) QT prolongation models are more susceptible to reentry induction than the no (N) QT prolongation model (reentry induced episodes for N, L, and G numbered 90, 120, and 122, respectively). This increased vulnerability was diminished when the QT interval was prolonged at all simulation sites (reentry induced episodes for the diffuse QT prolongation model, D model, numbered 82). Decreased QT dispersion might be important for the prevention of reentry induction regardless of whether the QT interval is increased.

Action Potentials↗
PubMed1996

Structural differences in the ability of lysophospholipids to inhibit endothelium-dependent hyperpolarization by acetylcholine in rat mesenteric arteries.

The effects of different lysophospholipids on endothelium-dependent hyperpolarization by acetylcholine were examined in rat mesenteric arteries. Lysophosphatidylcholine with 14 or longer carbon acyl chain significantly inhibited the hyperpolarization, while that with 12 or lesser carbon acyl chain was without effect. Lysophosphatidylcholine with unsaturated acyl chain also showed a potent inhibition. Lysophosphatidylinositol and lyso-platelet activating factor, but not phosphatidylcholine, lysophosphatidic acid, lysophosphatidylethanolamine or lysophosphatidylserine, suppressed the hyperpolarization. These results suggest that the length of the carbon acyl chain and the size of the polar head group may be crucial for the effects of lysophospholipids on endothelium-dependent hyperpolarization. Accumulation of these lysophospholipids may play an important role in endothelial dysfunction associated with atherosclerosis.

Acetylcholine↗
PubMed1996

Clonal analysis by polymerase chain reaction of B-cell lymphoma with late relapse: a report of five cases.

BACKGROUND: Little is known about the clonal heterogeneity of non-Hodgkin's lymphoma between presentation and relapse, although several such reports have been published on acute lymphoblastic leukemia. METHODS: We examined five patients with B-cell lymphoma who relapsed more than 5 years after initial presentation. Formalin fixed, paraffin embedded tissues were analyzed for clonal immunoglobulin heavy chain gene rearrangement by the polymerase chain reaction (PCR) and sequencing of the PCR products. Four specimens retained the original histologic type, but one showed histologic transformation from diffuse large cell lymphoma to follicular small cleaved cell lymphoma. RESULTS: Although the size of the PCR products looked identical on the gel between presentation and relapse in all patients, only three of the four specimens that retained the original type had identical gene rearrangements at both presentation and relapse. One of these four and the fifth specimen showed novel gene rearrangements. CONCLUSIONS: This study suggests that late relapse lymphoma may present as a new clone. Sequencing of the PCR products is important in the evaluation of clonal heterogeneity.

Adult↗
PubMed1996

Mutations in the nonstructural protein 5A gene and response to interferon in patients with chronic hepatitis C virus 1b infection.

BACKGROUND: A region associated with sensitivity to interferon has been identified in the nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) genotype 1b. The region spans amino acid residues 2209 to 2248 (NS5A2209-2248) of HCV-J, a strain of HCV-1b whose complete genomic sequence has been identified. We examined whether the NS5A2209-2248 sequence present before therapy could be used as a predictor of the response to interferon therapy in patients with chronic HCV-1b infection. METHODS: We retrospectively analyzed 84 patients with chronic HCV-1b infection who had received interferon alfa (total dose, 516 million to 880 million units) for six months. Pretreatment serum samples were analyzed. The amino acid sequence of NS5A2209-2248 was determined by direct sequencing of the HCV genome amplified by the polymerase chain reaction (PCR) and was compared with the established sequence for HCV-J. RESULTS: A complete response, as evidenced by the absence of HCV RNA in serum on nested reverse-transcription PCR for six months after therapy, did not occur in any of the 30 patients whose NS5A2209-2248 sequences were identical to that of HCV-J (wild type). Five of 38 patients (13 percent) with 1 to 3 changes in NS5A2209-2248 (intermediate type) had complete responses, as did all 16 patients with 4 to 11 amino acid substitutions (mutant type), indicating that the mutant type was significantly associated with a complete response (P < 0.001). Although baseline serum HCV RNA levels, as measured by a branched-chain DNA assay, were lower in patients with the mutant type of NS5A2209-2248 than in those with the other types (P < 0.001), multivariate analyses revealed that the number of amino acid substitutions in NS5A2209-2248 was the only variable associated with an independent effect on the outcome of interferon therapy (odds ratio, 5.3; 95 percent confidence interval, 1.6 to 18; P = 0.007). CONCLUSIONS: In patients with chronic HCV-1b infection, there is a substantial correlation between responses to interferon and mutations in the NS5A gene.

Amino Acid Sequence↗
PubMed1996

Complete nucleotide sequences of hepatitis B virus genomes associated with epidemic fulminant hepatitis.

Pre-core/core mutants are frequently observed in patients with fulminant hepatitis. To investigate the extent of molecular characteristics of hepatitis B virus (HBV) genomes implicated in the development of fulminant hepatitis, full-length HBV genomes were sequenced directly from sera of two patients with epidemic fatal fulminant hepatitis, after amplification by the polymerase chain reaction. These two genomes, of 3215 nucleotides, were 99.6% identical, indicating that a common source of HBV potentially caused fulminant hepatitis. Thirty unique nucleotide mutations were commonly found in the two entire HBV genomes. Three were located in the stem-loop structure, changing this element to a more stable structure. Twenty-five unique amino acid substitutions were found in each open reading frame, except for the X and pre-surface 2 genes. One was located in the pre-surface 1 gene; two were in the surface gene; three were in the pre-core gene, including codons 28 (tryptophan to stop codon) and 29 (glycine to aspartic acid); eight were in the core gene; and 11 were in the polymerase gene. The pre-core mutations at codons 28 and 29 were common to the two HBV strains reported previously in patients with epidemic fulminant hepatitis. Thus, HBV genomes associated with epidemic fatal fulminant hepatitis have numerous unique mutations, located mainly in the polymerase gene, as well as the pre-core/core gene, including mutations in the stem-loop structure of the pregenome encapsidation signal sequence. These mutations may be associated with the development of fulminant hepatitis.

Aged↗