Biomedical subjects

M Hirano

Publications and source records attributed to M Hirano.

At least 181 records · Page 10Linked to original sources

PubMed1998

Nucleotide sequence of plasmid pAQ1 of marine cyanobacterium Synechococcus sp. PCC7002.

We have determined the complete nucleotide sequence of pAQ1, the smallest plasmid of the unicellular marine cyanobacterium Synechococcus sp. PCC7002. The plasmid consists of 4,809 bp and has at least four open reading frames that potentially encode polypeptides of 50 or more amino acids. We found that a palindromic element, the core sequence of which is G(G/A)CGATCGCC, is over-represented not only in plasmid pAQ1 but also in the accumulated cyanobacterial genomic sequences from Synechococcus sp. PCC6301, PCC7002, PCC7942, vulcanus and Synechocystis sp. PCC6803 within GenBank and EMBL databases. It suggests that this sequence might mediate gene rearrangement, thus increasing genetic diversity, since recombination events are frequent in cyanobacteria.

Amino Acid Sequence↗

PubMed1998

Clinical and molecular genetic study in seven Japanese families with spinocerebellar ataxia type 6.

We report on seven Japanese families with spinocerebellar ataxia type 6 (SCA6) carrying small CAG repeat expansions in the calcium channel alpha1A subunit gene. The number of the expanded CAG repeat, ranged from 22 to 25, showed no intergenerational instability and had a significant inverse correlation with the age of onset. The clinical features of these patients were late onset progressive pure cerebellar ataxia with dysarthria and nystagmus, and are consistent with autosomal dominant cerebellar ataxia type III (ADCA type III). Magnetic resonance imaging scan of the brain demonstrated cerebellar atrophy with no evidence of brainstem involvement. We propose that clinical phenotype of SCA6 is compatible with ADCA type III and SCA6 is one of the most common types of ADCA in Japan.

Aged↗

PubMed1998

Intramolecular cross-linking of the extrinsic 33-kDa protein leads to loss of oxygen evolution but not its ability of binding to photosystem II and stabilization of the manganese cluster.

The extrinsic 33-kDa protein of photosystem II (PSII) was intramolecularly cross-linked by a zero-length cross-linker, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The resulting cross-linked 33-kDa protein rebound to urea/NaCl-washed PSII membranes, which stabilized the binding of manganese as effectively as the untreated 33-kDa protein. In contrast, the oxygen evolution was not restored by binding of the cross-linked protein, indicating that the binding and manganese-stabilizing capabilities of the 33-kDa protein are retained but its reactivating ability is lost by intramolecular cross-linking of the protein. From measurements of CD spectra at high temperatures, the secondary structure of the intramolecularly cross-linked 33-kDa protein was found to be stabilized against heat treatment at temperatures 20 degrees C higher than that of the untreated 33-kDa protein, suggesting that structural flexibility of the 33-kDa protein was much decreased by the intramolecular cross-linking. The rigid structure is possibly responsible for the loss of the reactivating ability of the 33-kDa protein, which implies that binding of the 33-kDa protein to PSII is accompanied by a conformational change essential for the reactivation of oxygen evolution. Peptide mapping, N-terminal sequencing, and mass spectroscopic analysis of protease-digested products of the intramolecularly cross-linked 33-kDa protein revealed that cross-linkings occurred between the amino group of Lys48 and the carboxyl group of Glu246, and between the carboxyl group of Glu10 and the amino group of Lys14. These cross-linked amino acid residues are thus closely associated with each other through electrostatic interactions.

Amino Acid Sequence↗

PubMed1998

Dominant negative effect of GTP cyclohydrolase I mutations in dopa-responsive hereditary progressive dystonia.

Hereditary progressive dystonia (HPD) is caused by the mutant gene encoding GTP cyclohydrolase I (GCH). The clinical presentation of this disease varies considerably, and many cases appear to be sporadic. We have previously proposed that this clinical variation may be due to differential expression of the mutant and normal GCH mRNA, presumably at the protein level. To provide support for this proposal, we studied a new Japanese family with HPD, in which 2 members were heterozygous for an exon-skipping mutation. This mutation produced truncated GCH, which shared 180-amino acid residues at the amino terminus of the normal enzyme (GCH180). An affected heterozygote had a higher mutant/normal mRNA ratio than an unaffected heterozygote, consistent with our previous finding in the HPD family with GCH114. A further study, using coexpression of the mutant with wild-type GCH in COS-7 cells, showed that three mutant GCHs inactivated the normal enzyme. GCH114 was most effective in enzyme inactivation, which was followed by GCH180 and a normally occurring mutant GCH209. These results suggested that the dominant negative effect of a mutant GCH on the normal enzyme might be one of the molecular mechanisms determining the heterogeneity of clinical phenotypes of HPD.

Adolescent↗

PubMed1998

Effects of ruthenium red on membrane ionic currents in urinary bladder smooth muscle cells of the guinea-pig.

Three major ionic currents, Ca2+-dependent K+ current (IK-Ca), delayed rectifier type K+ current (Ikd) and Ca2+ current (ICa), were activated by depolarization under whole-cell clamp in single smooth muscle cells isolated from guinea-pig urinary bladder. Externally applied ruthenium red (RuR) reduced the amplitude of IK-Ca and ICa at 0 mV (IC50 values were 4.2 and 5.6 muM, respectively), but did not affect IKd. Spontaneous transient outward currents (STOCs) and caffeine-induced outward currents (Icaf) at -30 mV were reduced by external 10 muM RuR. When 10 muM RuR was added to the pipette solution, IK-Ca during depolarization, STOCs and Icaf significantly decreased with time. RuR did not change the unitary current amplitude of the large-conductance Ca2+-dependent K+ (BK) channels, but reduced the open probability of the channel under excised patch-clamp recording mode. RuR reduced the channel activity more effectively from the cytosolic face than from the other. This inhibition decreased when the cytosolic Ca2+ concentration was increased. These results indicate that RuR blocks BK and Ca2+ channels in urinary bladder smooth muscle cells. The decrease in IK-Ca, STOCs and Icaf by RuR is attributable to the direct inhibition of BK channel activity, probably in addition to the inhibition of Ca2+ release from storage sites. The direct inhibition of BK channel activity by RuR may be related to the interaction of RuR with the Ca2+-binding sites of the channel protein.

Animals↗

PubMed1998

Autoregulation of the partition genes of the mini-F plasmid and the intracellular localization of their products in Escherichia coli.

The sopAB operon and the sopC sequence, which acts as a centromere, are essential for stable maintenance of the mini-F plasmid. Immunoprecipitation experiments with purified SopA and SopB proteins have demonstrated that these proteins interact in vitro. Expression studies using the lacZ gene as a reporter revealed that the sopAB operon is repressed by the cooperative action of SopA and SopB. Using immunofluorescence microscopy, we found discrete fluorescent foci of SopA and SopB in cells that produce both SopA and SopB in the presence of the sopC DNA segment, but not in the absence of sopC, suggesting the SopA-SopB complex binds to sopC segments. SopA was exclusively found to colocalize with nucleoids in cells that produced only SopA, while, in the absence of SopA, SopB was distributed in the cytosolic spaces.

Bacterial Proteins↗

PubMed1998

Hepatocyte growth factor accelerates restitution of intestinal epithelial cells.

Many cytokines are involved in the repair of damaged tissue, and one of these, hepatocyte growth factor (HGF), is involved not only with liver regeneration but also in the repair of other tissues. To investigate the importance of HGF in the repair of the small intestine, we evaluated its effect and that of other growth factors in IEC-6 cells, an intestinal epithelial cell line derived from normal rat small intestine. Round "wounds" were made in confluent monolayers of IEC-6 by silicon rubber-tipped steel rods and various cytokines; transforming growth factor alpha (TGF-alpha), transforming growth factor beta1 (TGF-beta1), keratinocyte growth factor (KGF), and HGF, were added. We photographed the repaired monolayers every 24 h and calculated the ratios of areas not covered by cells to initial areas. Cell proliferation with TGF-alpha, TGF-beta, KGF, or HGF was examined in terms of [3H]-thymidine uptake. Finally, we determined c-met (the HGF receptor) mRNA in the IEC-6 cells by Northern blot hybridization. HGF was the most potent of the cytokines in accelerating repair of the damaged monolayer of IEC-6. HGF was also 1.34 times more effective than control the medium for inducing cell proliferation of IEC-6. By Northern blot hybridization, three bands of mRNA bound to c-met cDNA. These results suggest that HGF is important in the repair of the small intestine.

Animals↗

PubMed1998

Mechanical strength of calcium phosphate cement in vivo and in vitro.

Two different kinds of calcium phosphate cement were developed for implant fixation: cement A comprised of alpha-tricalcium phosphate (alpha-TCP) 95% and dicalcium phosphate dihydrate (DCPD) 5%, and cement B comprised of alpha-tricalcium phosphate 90% and dicalcium phosphate dihydrate 10%. The compression strength and pullout force of the new materials were tested both in vitro and in vivo. Microscopic observations were performed on the interface between bone and cement. Cement A showed a greater mechanical strength than cement B. The results suggest the clinical possibility of this calcium phosphate cement, which could be used as a material for enhancing implant fixation.

Animals↗

PubMed1998

Management of cancer in the elderly: therapeutic dilemmas.

As the average life span has increased, the number of elderly patients with cancer has increased. One of the greatest dilemmas in the management of cancer in the elderly is the fact that often regular curative treatment cannot be executed. From this viewpoint, 679 patients with head and neck cancer treated during a recent 5-year period were reviewed. They were classified into two age groups: those younger than 75 years (n = 560) and those 75 years and older (n = 119). The frequency with which curative treatment could not be executed was 8.8% in the younger group and 26.1% in the older group. The major reasons were concomitant health problems and failure to obtain the patient's consent, and these problems were significantly more common in the older group. The incidence of asthma, pulmonary emphysema, cardiac failure, hypertension, arrhythmia, cerebrovascular disease, and kidney failure was greater in the older group. The overall 3-year survival rate was 18% in the cases with no curative treatment and 77% in those curatively treated.

Aged↗

PubMed1998

Vibrio vulnificus septicemia in a patient with severe aplastic anemia.

A 53-year-old man with severe aplastic anemia developed sporadic Vibrio vulnificus septicemia 1 day after eating raw fish and shellfish. Although V. vulnificus infection is potentially fatal, he was saved by immediate and sensitive antibiotic administration. Patients with chronic hematologic disease are susceptible to infection by this organism and are prone to developing septicemia when they eat raw seafood. It is necessary for a patient with this infection to be given effective antibiotics as quickly as possible.

Anemia, Aplastic↗

PubMed1998

Response-oriented individualized induction therapy followed by intensive consolidation and maintenance for adult patients with acute lymphoblastic leukemia: the ALL-87 study of the Japan Adult Leukemia Study Group (JALSG).

The Japan Adult Leukemia Study Group conducted the ALL-87 study to determine whether response-oriented induction therapy and intensive consolidation and maintenance/intensification therapies could increase complete remission (CR) rate and survival in adult acute lymphoblastic leukemia (ALL). Of 121 patients registered, 116 were evaluated. Patients' ages ranged from 15 to 72 years (median, 38 years). Induction therapy, which consisted of doxorubicin, vincristine, cyclophosphamide, L-asparaginase and prednisolone, was given in a response-oriented individualized fashion. Patients were randomly allocated either to receive or not, intrathecal chemotherapy on day 8 of the induction therapy. Complete remission (CR) was obtained in 97 (83.6%) patients (90.2%) in patients of less than 50 years of age and 67.6% in patients 50 years of age or older). At a median follow-up period of 65 months, the predicted 6-year overall survival and event free survival (EFS) rates of 116 patients were 23.4 and 20.0%, respectively. Predicted 6-year survival and disease-free survival (DFS) rates of 97 CR patients were 28.2 and 24.5%, respectively. By multivariate analysis, patients under 40 years of age (P = 0.002) or those with a platelet count of more than 100,000/microliters (P = 0.004) were significant favorable prognostic factors for obtaining CR, and days to CR less than 50 (P = 0.003), patients under 50 years of age (P = 0.005) were significant favorable factors for longer DFS. There was no significant difference in CR rates and DFS between the two randomized groups according to the intrathecal chemotherapy on day 8. Response-oriented induction therapy produced a high CR rate, but fairly intensive consolidation and maintenance/intensification chemotherapies resulted in only a marginal effect on DFS in adult ALL. Although age is one of the most important prognostic factors in ALL, the outcome was unsatisfactory even in younger adult patients using chemotherapeutic regimen employed in this study.

Adolescent↗

PubMed1998

Effects on gastric circulation of treatment for portal hypertension in cirrhosis.

We evaluated the gastric circulatory effects of the type of treatment administered for portal hypertension. Of 14 patients with cirrhosis, seven received a transjugular intrahepatic portosystemic shunt (TIPS; group T) and seven received percutaneous transhepatic portographic embolization (PTPE; group P). Patients were evaluated over the course of one year. After treatment, portal venous pressure was significantly reduced from 39 +/- 6 cm H2O to 32 +/- 5 (P < 0.001) in group T and was significantly elevated from 29 +/- 10 to 33 +/- 8 (P < 0.05) in group P. The portal flow velocity (Vmean) was significantly higher in group T vs group P (P < 0.0001). The congestion index was significantly lower in group T than in group P (P < 0.0001). The gastric mucosal blood flow was increased in group T but was unchanged in group P. Esophageal varices showed some improvement in both groups, but the portal hypertensive gastropathy was improved only in group T. These findings help to explain the differing effects on the gastric circulation related to the type of treatment used for portal hypertension.

Embolization, Therapeutic↗

PubMed1998

Morphological study of the intrapharyngeal ganglia and ganglionic neurons in cats.

The distribution, number and nature of intrapharyngeal ganglia and their neurons in cats were examined by means of serial sections, histochemical and immunohistochemical methods. Six to eight large ganglia around the palatine tonsils and five to eight small ganglia in the laterodorsal wall of pharyngeal mucous membrane were observed. The intrapharyngeal ganglionic neuron (25-30 microns in diameter) totalled 600-800 and more than 80% of them were located around the palatine tonsils. The ganglionic neurons were acetylcholinesterase reaction positive. On immunohistochemistry, many choline acetyltransferase-immunoreactive and vasoactive intestinal polypeptide-immunoreactive neurons and a few tyrosine hydroxylase-immunoreactive nerve cells were found, but no calcitonin gene-related peptide-immunoreactive or substance P-immunoreactive neurons were recognized in the ganglion. The present findings indicate that intrapharyngeal ganglionic neurons are mainly parasympathetic and partially sympathetic in nature.

Acetylcholinesterase↗

PubMed1998

Morphological observation of laryngeal motoneurons by means of cholera toxin B subunit tracing technique.

Gross anatomical and histological studies and immunohistochemical demonstration of cholera toxin B subunit used as a retrograde tracer were performed to investigate distinct muscle fibre bundles (MFBs) in the feline intrinsic laryngeal muscles (ILMs) and to characterize the respective supplying motoneurons in the nucleus ambiguus (AM). Distinct bundles were observed in all ILMs except the lateral cricoarytenoid muscle. Motoneurons supplying MFBs related to phonation located more medially than others. Motoneuron size did not differ between distinct MFBs in the same muscle. Neurodendrites for the cricothyroid muscle (CT) and adductor motoneurons extended dorsomedially, ventrolaterally and ventromedially, while those for the posterior cricoarytenoid muscle (PCA) motoneurons stretched dorsomedially and ventrolaterally. We conclude that distinct MFBs in ILMs play different roles in laryngeal functions, and that corresponding motoneurons have their own specific visceroneural nature allowing regulation of complex laryngeal functions. To receive information from the central nervous system, laryngeal motoneuron dendrites extended to regions locating respiratory, phonatory and swallowing neurons.

Animals↗

PubMed1998

Parvalbumin distribution in the musculature of the pharyngo-oesophageal segment.

The composition and size of muscle fibre types in the hyopharyngeus (HP), thyropharyngeus (TP), cricopharyngeus (CP) and cervical oesophageal muscle (CE) from 6 normal adult cats were investigated using parvalbumin (PA) immunohistochemistry. Fibre types I, IIA and IIB were identified in all muscles. HP and TP revealed predominance of type II fibres (74.8% and 75.2%, respectively), whilst CP and CE showed predominance of type I fibres (72.6% and 82.2%, respectively). The mean diameter of narrow fibres was greater in type II (23.9 microm) than in type I fibres (21.7 microm). The results seem to reflect the physiological features of each muscle, i.e. short rapid contractions of HP and TP, sustained contraction of CP and slow peristaltic movements of CE.

Animals↗

PubMed1998

Effects of gamma-rays on the populations of the steady-state ecological microcosm.

PURPOSE: To investigate the dose-response of an aquatic microcosm exposed to gamma-rays and to test the suitability of microcosms for elucidation of the mechanisms that account for such ecological effects. MATERIALS AND METHODS: The microcosm used in this study consisted of algae Euglena gracilis Z as a producer, protozoa Tetrahymena thermophila B as a consumer and bacteria Escherichia coli DH5alpha as a decomposer. After the steady-state microcosm was irradiated with 60Co gamma-rays at various dose levels, the population densities of each species were measured. RESULTS: Irradiation at up to 100 Gy did not affect the population of the microcosm except for a temporary decrease of E. coli just after irradiation. At 500 or 1000Gy, E. coli died out just after irradiation. Only Eu. gracilis and T. thermophila could survive. Their populations, however, decreased compared with that of each control, except for a temporary increase of T. thermophila after 1000 Gy irradiation. These population changes were attributable to the extinction of E. coli in addition to the direct effects of radiation. Irradiation at 5000 Gy extinguished all species in the microcosm. CONCLUSIONS: The response of the microcosm to radiation was dose-dependent over a range of high doses. The microcosm was also shown to be suitable for examining not only direct effects but also secondary effects.

Animals↗

PubMed1998

Mitochondrial neurogastrointestinal encephalomyopathy syndrome maps to chromosome 22q13.32-qter.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) syndrome is a rare, multisystem disorder characterized clinically by ptosis, progressive external ophthalmoplegia, gastrointestinal dysmotility, leukoencephalopathy, thin body habitus, and myopathy. Laboratory studies reveal defects of oxidative-phosphorylation and multiple mtDNA deletions frequently in skeletal muscle. We studied four ethnically distinct families affected with this apparently autosomal recessive disorder. Probands from each family were shown, by Southern blot, to have multiple mtDNA deletions in skeletal muscle. We mapped the MNGIE locus to 22q13.32-qter, distal to D22S1161, with a maximum two-point LOD score of 6.80 at locus D22S526. Cosegregation of MNGIE with a single chromosomal region in families with diverse ethnic backgrounds suggests that we have mapped an important locus for this disorder. We found no evidence to implicate three candidate genes in this region, by using direct sequence analysis for DNA helicase II and by assaying enzyme activities for arylsulfatase A and carnitine palmitoyltransferase.

Adolescent↗

PubMed1998

Clinical similarities of hereditary progressive/dopa responsive dystonia caused by different types of mutations in the GTP cyclohydrolase I gene.

OBJECTIVE: Hereditary progressive dystonia with pronounced diurnal fluctuation [(HPD)/dopa responsive dystonia (DRD)] is a childhood onset dystonia which responds to levodopa. Various clinical signs and symptoms of HPD/DRD have been recognised to date. Mutations in the GTP cyclohydrolase I (GTP-CH-I) gene were recently identified as the cause of HPD/ DRD. In the present study, the GTP-CH-I gene and the clinical features of eight HPD/DRD patients from six families were analysed to determine the correlations between clinical expression and the mutations in the GTP-CH-I gene. METHODS: The exons, exon-intron junctions, and an indispensable part of the 5' flanking region of the GTP-CH-I gene were sequenced in the eight clinically diagnosed patients with HPD/DRD and their asymptomatic parents. RESULTS: Three independent mutations in the GTP-CH-I gene were found in three patients. One of the patients and her asymptomatic mother were heterozygous for a novel mutation at the initiation codon. The three patients with dissimilar GTP-CH-I mutations exhibited similar clinical features. The other five patients with normal sequences presented several features not manifested by the three patients with the mutations. No mutation was found in the 5' flanking region of any patients or their parents. CONCLUSIONS: A novel initiation codon mutation was found in a Japanese patient with HPD/DRD. The clinical manifestations common to the patients with HPD/ DRD with a mutated GTP-CH-I gene were also identified. Although focal manifestations of HPD/DRD associated with the mutations of this gene will be broadened, it is inferred that these clinical features are fundamental to HPD/DRD caused by mutations in this gene.

Adolescent↗