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Biomedical subjects

Y Shiga

Publications and source records attributed to Y Shiga.

At least 55 records · Page 3Linked to original sources
PubMed1999

The neuroprotective agent MS-153 stimulates glutamate uptake.

We investigated the effect of (R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), a novel neuroprotective agent, on L-[3H]glutamate uptake through GLT-1, a Na(+)/K(+)-dependent glial glutamate transporter, expressed in COS-7 cells. MS-153 (1-100 microM) accelerated the L-[3H]glutamate uptake through GLT-1 in a concentration-dependent and time-dependent manner. Eadie-Hofstee analysis revealed that MS-153 significantly decreased the K(m) of the glutamate uptake by COS-7 cells expressing GLT-1. In contrast, [3H]gamma-aminobutyric acid (GABA) uptake through a glial GABA transporter was not affected. In addition, MS-153 increased Na(+) currents through GLT-1 expressed in Xenopus oocytes. We also investigated the effect of MS-153 on amino acid efflux from rat hippocampal slices. The increase in glutamate efflux induced by 50 mM KCl was significantly attenuated by the treatment with MS-153 at 10 microM, while MS-153 had no significant effect on the K(+)-evoked efflux of GABA. Furthermore, the increase in glutamate efflux by ischemia (hypoxia/aglycemia) was partially, but significantly inhibited by MS-153. These results suggest that the cerebroprotective effect of MS-153 in this ischemic model in vivo is due to the specific reduction of the glutamate concentration in the extracellular space, which can probably be attributed to the acceleration of glutamate uptake by the indirect modulation of the glutamate transporter activity.

ATP-Binding Cassette Transporters↗
PubMed1999

Transposition of IS1 circles.

BACKGROUND: IS1, the smallest active transposable element in bacteria, encodes transposase. IS1 transposase promotes transposition as well as production of miniplasmids from a plasmid carrying IS1 by deletion of the region adjacent to IS1. The IS1 transposase also promotes production of IS1 circles consisting of the entire IS1 sequence and a sequence, 6-9 bp in length, as a spacer between terminal inverted repeats of IS1. The biological significance of the generation of IS1 circles is not known. RESULTS: Plasmids carrying an IS1 circle with a spacer sequence 6-9 bp long transposed to target plasmids at a very high frequency when transposase was produced from a co-resident plasmid. The products were target plasmids with the donor plasmid inserted at the ends of IS1 in the IS1 circle. This insertion accompanied the removal of the spacer sequence and duplication of the sequence at the target site. IS1 circles with a much longer spacer sequence transposed less frequently. The SOS response was induced in cells harbouring a plasmid with an IS1 circle owing to transposase. IS1 circles could transpose in the strain deficient in H-NS, a nucleoid-associated DNA-binding protein known to be required for the transposition of IS1. CONCLUSIONS: IS1 circles appear to act as intermediates for simple insertion into the target DNA via cleavage of the circles which induces the SOS response. H-NS may function in promoting the assembly of an active IS1 DNA-transposase complex at the terminal inverted repeats.

Bacterial Proteins↗
PubMed1999

1,5-Anhydroglucitol promotes glycogenolysis in Escherichia coli.

Glycogen is a storage compound that provides both carbon and energy, but the mechanism for the regulation of its metabolism has not been fully clarified. Recently, we found a new glycogenolytic pathway in rat liver in which glycogen is first metabolized to 1, 5-anhydrofructose (AnFru) and then to 1,5-anhydroglucitol (AnGlc-ol). Because the amounts of glycogen and AnFru are closely related in various rat organs and the second reaction, AnFru to AnGlc-ol, is strongly inhibited in the presence of glucose, we expected that this pathway might play a regulatory role in glycogen metabolism. Here we evaluate the expected involvement of AnGlc-ol and AnFru in the regulatory mechanism in Escherichia coli C600. Having established the presence of this new glycogenolytic pathway in E. coli C600, we further show that the conversion of AnFru to AnGlc-ol is activated only after the exhaustion of glucose in the medium, and that as little as 5 microM AnGlc-ol in the medium acutely accelerates the degradation of glycogen by 40%. We consider the role of AnGlc-ol in the mechanism that controls glycogen metabolism in E. coli to be as follows. When glucose is abundant, E. coli accumulate glycogen, a fraction of which is steadily degraded so that the amount of AnFru is about 1/1,000 of glycogen on a weight basis. When glucose is depleted and the demand for glycogen utilization is elevated, AnFru, which has accumulated mostly in the medium, is promptly taken up and converted to AnGlc-ol, which accelerates glycogen degradation. We also suggest the possibility that AnGlc-ol is one of the extracellular signaling molecules for bacteria.

Carbohydrate Sequence↗
PubMed1999

Therapeutic efficacy of transcranial magnetic stimulation for hereditary spinocerebellar degeneration.

We applied transcranial magnetic stimulation (TMS) as a therapeutic approach for patients with spinocerebellar degeneration (SCD). The subjects were four familial SCD patients (three men and one woman) aged from 27 to 76 years old. They were genetically analysed as two spinocerebellar ataxia type 6 (SCA 6), one SCA 1, and one SCA 7. The durations of their illness ranged from 1 to 7 years. Ten consecutive magnetic pulses were delivered over the scalp corresponding to the right cerebellar hemisphere, the middle of the cerebellum and the left cerebellar hemisphere, respectively, every day for 21 days. In all patients, the time and the number of steps required for a 10 m walk examination were significantly decreased after TMS trial compared with those before TMS. The number of feasible steps in tandem gait test increased. The total length of tracing body balance for 30 seconds measured by gravinometer was significantly decreased. However, nystagmus, dysarthria or incoordination of the upper limbs did not change after TMS trial. It is of interest that the blood flow of the cerebellar hemisphere, putamen and pons were significantly increased during the TMS trial. Although we do not know the exact mechanism by which TMS improved the ataxic gait, we speculate the increase of blood flow in the cerebellum, putamen and pons takes part in the improvement. These findings suggest that TMS over the cerebellum may be an effective therapy for patients with SCD.

Adult↗
PubMed1999

Bronchial amyloidosis successfully treated with low-dose long-term erythromycin therapy.

A 69-year-old man was admitted for evaluation of an abnormal chest X-ray. A diagnosis of primary bronchial amyloidosis was made on the basis of the chest X-ray, CT scans and bronchial biopsy specimens. The patient was treated with low-dose long-term erythromycin therapy (600 mg/day). After four months of therapy, chest CT scans, bronchoscopic findings and bronchial biopsy specimens revealed significant improvement of inflammatory changes. Low-dose erythromycin therapy may be helpful in terms of its anti-inflammatory effects for patients with bronchial amyloidosis.

Aged↗
PubMed1999

[Steroid-responsive diffuse cerebral white matter lesions in a case of intractable fungal meningoencephalitis].

We report a case of fungal meningoencephalitis with steroid-responsive diffuse cerebral white matter lesions. A 49-year-old male developed auditory hallucination, confusion and fever, on April, 1994. He was diagnosed as having cryptococcal meningoencephalitis based on the detection of cryptococcal antigens in the cerebrospinal fluid (CSF). Intravenous administration of fluconazole resulted in improvement of his neurologic symptoms and CSF findings. For the next seven months, he was treated with oral fluconazole and the neurological status was stable. However, soon after the dose of fluconazole was tapered, he became confused and febrile, which made him admitted to our hospital. Neurological examination on admission showed disturbance of consciousness, disorientation and meningeal irritation. The CSF examination revealed mild pleocytosis (mostly lymphocytes), elevated protein and normal glucose levels, although fungus was not detected. The T2-weighted image of brain MRI demonstrated diffuse hyperintense lesions in the bilateral cerebral white matters. GD-DTPA enhanced MRI showed spotty enhanced lesions in the periventricular white matters. The neurologic symptoms were once relieved after intravenous administration of fluconazole was started, but two months later, he became comatose and needed ventilatory support, despite amphotericine B therapy. Then, a needle brain biopsy targeting the white matter lesion was done. Histopathology of the specimen showed chronic inflammation with granuloma formation and T lymphycyte infiltrate around the small vessels, though fungus was not detected in the tissue. Combined therapy with corticosteroid and antifungal agents remarkably improved the neurological symptoms as well as the MRI findings. In the present case, fungal infection possibly induced an altered immune reactions which resulted in the steroid responsive diffuse cerebral white matter lesions.

Anti-Inflammatory Agents↗
PubMed1999

[Short- and long-term outcome after urethroplasty in the patients with hypospadias treated by Hodgson III method].

Between 1977 and 1997, 29 patients with hypospadias were surgically treated by Hodgson type III urethroplasty at Tsukuba University Hospital. The duration of surgery ranged from 150 to 535 minutes with an average of 269.3 minutes and the urethral catheter was removed between 4 and 14 days (average 8.7 day) after surgery. The postoperative hospital stay ranged from 10 to 29 days with an average of 18.4 days. The overall success rate of initial surgery was observed in 18 of the 29 patients (62.1%). As early postoperative complications, urethral fistula and stricture were seen in 10 (34%) and 3 (10%) patients, respectively; of these four fistulas persisted. As late complications revealed by questionnaire, erectile disorder was observed in one case. To obtain a higher success rate on initial treatment, skillful surgical technique and selection of appropriate cases are required.

Adolescent↗
PubMed1998

Development of new tester strains derived from E. coli WP2uvrA for the determination of mutational specificity.

We have developed a set of multipurpose tester strains (WP3101 to WP3106) derived from E. coli WP2uvrA for the detection and classification of mutagens. Six kinds of F' plasmid (lacI, lacZ, proAB+) in strains CC101-CC106, each of which carried a different lacZ allele, were transferred to a delta(lac-pro) derivative of WP2uvrA. Assays for transitions and transversions are based upon Lac+ reversion of a specific mutation located within the lacZ gene on an F' plasmid in strains WP3101-WP3106. In addition, the trpE65(ochre) allele in the same strains is available for Trp+ reversion assays. Using the new tester strains, we investigated the mutational specificities of various chemical mutagens. Base analog mutagens and alkylating mutagens induced specific types of base substitutions. G:C-->A:T transitions and G:C-->T:A transversions predominated in mutagenesis induced by 4-nitroquinoline 1-oxide. Only a slight increase in G:C-->T:A transversions was observed in cells treated with 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), although the potent mutagenicity of AF-2 was detected in a concurrent Trp+ reversion assay in the same strain. Sodium azide, on the other hand, was negative in the Trp+ reversion assay but specifically induced G:C-->A:T transitions. Present finding suggested that target sites for AF-2- and azide-induced lesions may largely depend on sequence context.

4-Nitroquinoline-1-oxide↗
PubMed1998

An assay system for detecting environmental toxicants with cultured cladoceran eggs in vitro: malformations induced by ethylenethiourea.

An in vitro assay system using cladoceran eggs was developed for the detection of toxic compounds in the aquatic environment. Parthenogenetic eggs of Daphnia magna were removed from the brood chambers of female adults and cultured individually in 96-well microtiter plates with Elendt M7 medium at 23 degrees C. Embryonic development proceeded completely in vitro with more than 95% hatchability. Egg development time in vitro was 2 days, which was almost equal to that in the brood chamber of the mother. Ethylenethiourea, a compound teratogenic to mammals, was investigated for toxicity to development of eggs. Isolated eggs were cultured in the presence of ethylenethiourea during the period of embryonic development for 3 days. Treatment with ethylenethiourea induced morphological abnormalities in the cladoceran carapace. Parthenogenetic eggs of Cladocera are genotypically identical, which makes them useful biological materials for a toxicity test on aquatic pollutants.

Animals↗
PubMed1998

Complement activation as a cause of transient hypotension during plasmapheresis.

Hypotension is one of the most common adverse effect of plasmapheresis (PP) and often is attributed to hypovolemia due to extracorporeal circulation and the vasovagal reflex. Complements are activated during PP, and the activated complements are strong anaphylatoxins and potent vasodilators. Therefore, we studied the relationship between the transient hypotension and the plasma levels of activated complements during and after PP in 8 sessions of 7 patients using the Plasmafro OP-08 as a plasma separator. Five of the patients underwent immunoadsorption PP using the IM-TR 350 or IM-PH 350 as the adsorption column. The other underwent double filtration PP using the Evaflux 4A as a second filter. In 4 of 8 sessions, patients experienced transient hypotension with significantly elevated plasma levels of activated complements C3a and C5a. In contrast, patients without hypotension showed no increases in C3a and C5a values during PP. In this report, we emphasize the critical role of activated complements for hypotension during PP.

Adolescent↗
PubMed1998

Histiocytic sarcoma of the spleen associated with hypoalbuminemia, hypo gamma-globulinemia and thrombocytopenia as a possibly unique clinical entity--report of three cases.

We report three patients with histiocytic sarcoma of the spleen associated with severe hypoalbuminemia, hypo gamma-globulinemia and thrombocytopenia. After the clinical diagnosis of splenic tumor of unknown origin was made, all three patients underwent splenectomy. The histiocytic origin of the tumor was confirmed histopathologically and immunohistochemically using a panel of antibodies. In contrast to malignant histiocytosis (MH), which typically reveals severe generalized clinical manifestations and a rapidly fatal course caused by the disseminated proliferation of neoplastic histiocytes, these patients were asymptomatic or showed only mild clinical symptoms for a long period of time until the recurrence was detected by which time the tumor cells had already spread to other organs. All three cases were characteristically associated with hypoalbuminemia, hypo gamma-globulinemia and thrombocytopenia, which returned to normal after splenectomy. Splenic histiocytic sarcoma with the features described here may represent a unique clinical entity, distinct from MH.

Adult↗
PubMed1997

Cloning and analysis of a cDNA encoding a two-domain hemoglobin chain from the water flea Daphnia magna.

A cDNA encoding a two-domain hemoglobin (Hb) chain of Daphnia magna was cloned and its nucleotide (nt) sequence of 1261 bp was determined. The nt sequence contained 74 bp of the leader sequence, 1047 bp of an open reading frame (ORF), and 119 bp of the 3'-untranslated region (UTR), excluding the polyadenylation tail. A sequence, AATACA, located 24 bp upstream from the polyA sequence was considered to be a polyadenylation signal. cDNA-derived amino acid (aa) sequence revealed that D. magna Hb chain is synthesized as a secretory precursor with a signal peptide of 18 aa. Mature D. magna Hb chain consists of 330-aa residues with a calculated molecular weight of 36227, which is composed of two large repeated domains, domain 1 and 2. Several key aa that are invariant in all or most of other Hb and required for functional heme-binding are conserved in each of the two domains. The N-terminal extension (pre-A segment) of domain 1 was unusually long and contained an unusual threonine-rich sequence. The homology between the aa sequences of the two domains (24% identity) was much lower than that observed in other two-domain Hb chains from clams or nematode. Hb mRNA level in D. magna reared under low oxygen concentration was more than 12 times higher than that in D. magna reared with sufficient aeration, indicating that the expression of Hb gene is regulated by mRNA level.

Amino Acid Sequence↗
PubMed1997

Chronic myelogenous leukemia with a hypooctoploid cell population.

A patient with chronic myelogenous leukemia who underwent transformation from the accelerated phase to the chronic phase with interferon-alpha treatment is reported. On admission, the numbers of myeloblasts and promyelocytes in the peripheral blood and bone marrow were 7.0% and 12.8%, respectively. The platelet count was 633.6 x 10(4)/microliter, and megakaryocytes were frequent in the bone marrow. In the accelerated phase, cytogenetic analyses revealed a hypotetraploid and a hypooctoploid cell population with two and four Philadelphia chromosomes, respectively, in the bone marrow specimen. The hypooctoploid clone disappeared with administration of interferon-alpha and the hypotetraploid clone also subsequently disappeared.

Aged↗
PubMed1997

Contribution of neutrophils to lipopolysaccharide-induced tumor necrosis factor production and mortality in a carrageenan-pretreated mouse model.

Carrageenan (CAR) pretreatment primes mice for lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-alpha production in sera and increases their mortality rate. To study the contribution of neutrophils in this model, blood neutrophil count was regulated with cyclophosphamide. After LPS challenge, both serum TNF-alpha activity and mortality risk ratio were significantly higher in neutrophilic mice, but significantly lower in neutropenic mice. In vitro, CAR treatment primed for TNF-alpha production of blood neutrophils, but conversely, that of monocytes was suppressed. We suggest that neutrophils are the major cells to produce TNF-alpha and to determine mouse mortality after LPS challenge in the mouse CAR model.

Animals↗
PubMed1997

Cerebroprotective effects of a novel pyrazoline derivative, MS-153, on focal ischemia in rats.

MS-153 ((R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline) is a novel pyrazoline compound that has potent cerebroprotective effects in the rat focal cerebral ischemia model. Middle cerebral artery (MCA) occlusion in rats allows detailed assessment of both functional and morphological sequelae of brain infarct. Using this model, we evaluated the cerebroprotective effects of MS-153. Treatment with MS-153 (12.5 mg/kg, i.v. bolus followed by 6.25 mg/kg/hr or 25.0 mg/kg, i.v. bolus followed by 12.5 mg/kg/hr infusion for 7 days) significantly reduced infarct volumes and improved neurological deficits in MCA occluded rats 7 days after occlusion. Delayed treatment significantly reduced infarct volume 24 hr after MCA occlusion when MS-153 (25.0 mg/kg, i.v. bolus followed by 12.5 mg/kg/hr infusion for 21 hr) administration was started 3 hr after occlusion. Brain edema was also significantly improved when MS-153 (25.0 mg/kg, i.v. bolus followed by 12.5 mg/kg/hr infusion for 18 hr) administration was started 6 hr after occlusion.

Analysis of Variance↗
PubMed1997

[A case of Ki-1 lymphoma-associated eosinophilic polymyositis].

We report on a patient of Ki-1 lymphoma-associated hypereosinophilic syndrome and eosinophilic polymyositis. A 22-year-old male was admitted to a hospital because of anterior chest pain, when he had a white cell count of 12,000 with 33% of eosinophils. He first noticed muscle weakness in the right shoulder at age 23 years. At the age of 25, he experienced marked muscle weakness in his arms and neck, which brought him to our hospital. Neurological examination on admission revealed moderate muscle atrophy and weakness in the neck flexors and both upper extremities, and marked muscle hypertrophy in the sternocleidomastoideus and trapezius muscles. Laboratory studies showed a white blood cell count of 17,700 with 56% of eosinophils. His serum creatine kinase (CK) level was elevated to 347 units. A muscle biopsy specimen showing active myositis infiltrated by eosinophils confirmed the diagnosis of eosinophilic myositis. Although eosinophilia and serum CK activity decreased markedly with corticosteroid treatment, his muscle weakness was unchanged. At the age of 27 years, lymphadenopathy developed. Immunocytochemical examination on a biopsied neck lymph node indicated Ki-1 lymphoma with positive Ki-1, CD45 and epithelial membrane antibodies. In spite of chemotherapy and local irradiation treatment, he died four months after the emergence of Ki-1 lymphoma. We discussed the relationship between hypereosinophilic syndrome, eosinophilic polymyositis and Ki-1 lymphoma on pathogenetic mechanism.

Adult↗
PubMed1997

[A juvenile case of Lambert-Eaton myasthenic syndrome with severe emaciation].

Most of the patients with Lambert-Eaton myasthenic syndrome (LEMS) are over 40 years of age at onset and have a malignant neoplasm, especially pulmonary small cell carcinoma. Juvenile cases of LEMS are rare and have not been reported in Japan. We report a 21-year-old women whose onset of LEMS was at 17 years of age. In the early stage of the disease, she had limb muscle weakness and was diagnosed has having seronegative myasthenia gravis (MG) based on decrementing response in low frequency repetitive nerve stimulation, positive edrophonium test, and negative serum anti-acetylcholin receptor antibodies. Serum anti-voltage-dependent-calcium-channel (VGCC) antibody was negative with an available assay system. She was thymectomized and received anti-cholinesterases, corticosteroids, and cyclophosphamide, but their therapeutic effects were not evident. Two years later, she was confined to bed due to sever emaciation (Her body weight reduced from 47 Kg to 27 Kg.), bulbar palsy, and limb muscle weakness. She needed respiratory support and tube feeding. Type II fiber atrophy, which is non-specific, but is a common finding in LEMS, was seen in the biopsied muscle of the patient. On the other hand, postsynaptic folds and clefts of all seven motor end-plates in the specimen were normal, which is against the diagnosis of MG. Recently, she was found to have anti-VGCC antibody with an improved assay system. Despite vigorous examination, no malignancy or other autoimmune disorders have been found. 3,4-Diaminopyridine was effective to improve limb muscle powers, but she is still bedridden.

Adult↗