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Biomedical subjects

K Arimoto

Publications and source records attributed to K Arimoto.

16 recordsLinked to original sources
PubMed1996

Purification and properties of D-aspartate oxidase from Cryptococcus humicolus UJ1.

D-Aspartate oxidase (EC 1.4.3.1), which is highly specific to D-aspartate, was inducibly produced by a yeast strain which was isolated from soil and identified as Cryptococcus humicolus UJ1. The enzyme was purified to homogeneity as indicated on SDS-polyacrylamide gel electrophoresis. The molecular mass of the monomer subunit was determined to be 40 kDa. The native enzyme was suggested to be a homotetramer by its behavior on gel filtration. The enzyme was shown to be a flavoprotein by its absorption spectral properties, and the flavin was found to be tightly, but not covalently, bound FAD. The purified preparation had a specific activity of 76.1 mumol/min per mg protein with D-aspartate as substrate. Optimum pH was 7.5 and optimum temperature was around 35 degrees C. D-Glutamate was a very poor substrate for the enzyme. N-Methyl-D-aspartate was better than D-glutamate as substrate but markedly poorer than D-aspartate. Malonate was the most effective competitive inhibitor of the compounds tested. The N-terminal amino-acid sequence of the enzyme showed a significant homology with those of D-aspartate oxidases from beef kidney and Octopus vulgaris and those of D-amino-acid oxidases from various sources.

Amino Acid Oxidoreductases↗
PubMed1995

Decrease of NCAM expression and astrocyte-neurone interaction in long-term cultured astrocytes.

In order to assess the characteristics of the older astrocyte, we obtained long-term cultured rat astrocytes (20 months) and examined the features of protein expression in relation to neuronal interaction. In short-term cultured astrocytes, NCAM expressed strongly in contrast to weak expression of laminin by both immunocytochemical and ELISA assay. On the contrary, in long-term cultured astrocytes, a marked decrease of NCAM expression was observed along with increased laminin expression compared with short-term cultured astrocytes. The long-term cultured astrocytes remained positive to anti-GFAP antibody and showed a much lower ability to interact with neurones than the short-term cultured astrocytes. NCAM may be one of the responsible molecules related to the astrocyte-neurone interaction in the developing and ageing nervous system.

Animals↗
PubMed1995

[Neurological involvements with transient gait disturbance in subacute phase of Kawasaki disease; a case report].

A 1-year-and-9-months old boy with gait disturbance during the 3rd week of Kawasaki disease (KD) was described. He had been previously healthy, and developed high fever and rash. The diagnosis of KD was based on 5 of 6 major criteria on the 3rd clinical day. He was initially treated with intravenous gamma-globulin 400 mg/kg/day for five days. On the 17th clinical day, the patient developed gait disturbance after most clinical signs disappeared. His gait was wide- based and unstable. Generalized hypotonia with poor traction response was also seen. Pyramidal tract signs including exaggerated patellar and Achilles tendon reflexes and positive bilateral Mendel-Bechterew reflex were presented. Cerebrospinal fluid was normal. Brain CT, MRI, and 123I-IMP SPECT images were normal without broad hemorrhage or infarction of the cerebral parenchyma. Gait disturbance recovered spontaneously within one month without any sequelae.

Central Nervous System Diseases↗
PubMed1992

[N-isopropyl-p-[I123] iodoamphetamine single photon emission computed tomography (I123-IMP SPECT) and child neurology].

We studied the clinical usefulness of I123-IMP SPECT in 50 pediatric patients with CNS disorders, which were categorized into the convulsive disorder group (n = 20), the cerebrovascular disorder group (n = 10), the acute encephalopathy or CNS infection group (n = 10), the metabolic or degenerative disorder group (n = 6), the congenital abnormality group (n = 2) and the migraine group (n = 2). The findings obtained were compared with those of cranial CT. I123-IMP SPECT revealed abnormal findings in 45 out of the 50 patients (90%), although cranial CT showed abnormal findings in only 24 patients (48%). This difference was statistically significant (p less than 0.01). In all groups except the migraine, we could find abnormal findings in more than 90% of the patients. Out of 28 patients without focal findings on the initial CT scanning, I123-IMP SPECT showed focal abnormalities in 26 patients (93%). Moreover in many patients with focal neurological abnormalities, we found focal abnormalities of I123-IMP SPECT related with neurological abnormalities of the patients. From these findings, we think I123-IMP SPECT might be better to CT scanning in examining a localized lesion. It was found that in many patients with focal abnormalities in CT scanning, I123-IMP SPECT showed larger abnormalities in CT scanning. By using I123-IMP SPECT we might be able to study the blood perfusional state surrounding the abnormal area shown by CT. In 3 patients with acute cerebrovascular disorders, I123-IMP SPECT revealed abnormal findings 3 to 11 days earlier than cranial CT.I123-IMP SPECT might be useful for early recognition of the pathological state.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

[A new automated renal biopsy technique under ultrasound guidance].

We evaluated a new automated biopsy device for percutaneous renal biopsies under ultrasound guidance, which was recently introduced in Japan for prostate biopsies. This device (Biopty-Gun: Bard Biopty Instrument Uppsala, Sweden) employs a Tru-Cut type smaller needle (18 gauge). We were able to obtain one or two renal tissues in all 57 cases with great ease and in little time. The length of specimen was sufficient (5-17 mm), but the width was thinner than the samples with the Vim-Silverman or Tru-Cut needles. We could achieve a definitive pathological diagnosis in 54 of 57 cases (94.7%), but now, we try to obtain two pieces of tissue for taking more adequate tissue. Only three patients had perirenal hematomas noted by computerized tomography or ultrasonography. We believe that this new automated technique offers a safer and more effective means of obtaining renal tissue.

Adolescent↗
PubMed1988

Abnormal 13C-fatty acid breath tests in patients treated with valproic acid.

Breath tests using fatty acids labeled with a stable isotope (carbon 13) were carried out on epileptic patients treated with valproic acid in order to detect abnormal fatty acid metabolism. The patients were given 13C-octanoic acid or 13C-palmitic acid orally, and expired air was collected at appropriate intervals for the analysis of 13CO2 content by a mass spectrometer. Eight patients were tested in the palmitic acid breath test and nine patients in the octanoic acid breath test. Controls for these tests were patients treated with antiepileptic drugs other than valproic acid and unmedicated cerebral palsy patients. In the valproic acid-treated group, 13C recovery was reduced by 56% in seven hours on the 13C-palmitic acid breath test, while the octanoic acid breath test showed a 52% reduction in one hour. This suppression of fatty acid oxidation was significantly correlated with dose of valproic acid in both tests. No influence of other drugs was detected, and the effect of administered carnitine was not conclusive. This study demonstrates the usefulness of 13C-labeled fatty acid breath tests in clinical practice.

Adolescent↗
PubMed1986

Expression of alpha 2-glycoprotein by glial precursor cells: an immunocytochemical study with glial cultures.

Studies on the presence of the brain-specific alpha 2-glycoprotein in cultures of newborn rat brain cells revealed that a population of glial precursor cells expressed this antigen at an early stage of development. This cell population consisted of small, phase-dark cells that proliferated in culture and occupied the surface of a layer of flat epithelial-like astrocytes. The latter cell type did not react with the antibodies. The number of alpha 2-glycoprotein positive cells gradually decreased from a high concentration of 88% of the total overlying cells at 6 days of culture to 44% at 23 days. The morphological heterogeneity of the overlying cells was noticeable after 10 days in culture as clusters of cells with elaborate processes started to develop. alpha 2-Glycoprotein was found to be concentrated in these structures. A glioma cell line (C-6 glia) which represents a unique in vitro model for the glial progenitor cells, was also found to express this glycoprotein antigen.

Animals↗
PubMed1985

Reduction of acid sphingomyelinase activity in human fibroblasts induced by AY-9944 and other cationic amphiphilic drugs.

AY-9944 (trans-1,4-bis(2-chlorobenzylaminoethyl)cyclohexane dihydrochloride), a cationic amphiphilic drug, caused a rapid, irreversible and dose-dependent reduction of acid sphingomyelinase activity in normal human fibroblasts without changing the activities of other lysosomal hydrolases tested. Examinations of activities against synthetic substrates and of the pH-dependency of sphingomyelinase in the drug-treated cells also suggested that the reduction of activity was specific to acid sphingomyelinase. Such a specific reduction was also found with 12 other cationic amphiphilic drugs, most of which have been shown to be inducers of experimental phospholipidosis in animals and/or cultured cells. These results strongly suggest that acid sphingomyelinase is involved in the process of drug-induced lipidosis. The reduction of acid sphingomyelinase seemed not to be due to direct inhibition by these drugs, a specific loss of the enzyme into the culture medium, the presence of inhibitor in the drug-treated cells, or impaired synthesis of the enzyme. There was no indication that changes in the catalytic properties of the enzyme, or changes in the requirement of detergents for its activity occurred in the cell. These results suggest that AY-9944 and other cationic amphiphilic drugs may cause the reduction of acid sphingomyelinase activity by inducing an increased rate of degradation of the enzyme or by causing an irreversible inactivation via some undetected factor.

Cations↗
PubMed1982

7 beta,12 beta-Dihydroxy-5 beta-cholan-24-oic acid as an internal standard for quantitative determination of bile acids by gas chromatography.

In order to find an artificial internal standard compound for quantitative determination of bile acids by gas chromatography, 7 alpha,12 alpha-, 7 alpha, 12 beta-, 7 beta, 12 alpha- and 7 beta,12 beta-dihydroxy-5 beta-cholan-24-oic acids were chemically synthesized with cholic acid (1) as the first starting material. The gas chromatographic retention time of 7 beta,12 beta-dihydroxy-5 beta-cholan-24-oic acid (beta beta-isomer) was more different from that of natural bile acids than the other isomers. Moreover, beta beta-isomer was extracted in the same fraction as the bile acids from urine, and no urinary substance had the same retention time as beta beta-isomer. No artifact was produced from beta beta-isomer during the analysis procedure. It was concluded that the beta beta-isomer is an internal standard compound with certain advantages for the quantitative determination of bile acids in urine by gas chromatography, irrespective of the recovery rate during the analysis procedure.

Bile Acids and Salts↗
PubMedDate not supplied

Clinical effects of allopurinol on intractable epilepsy.

We studied the clinical efficacy of allopurinol as add-on therapy in 31 patients with intractable epilepsy. When administered for a short time, allopurinol was effective in 17 patients (55%); 8 were seizure-free, 8 had 75% decrease in seizure frequency, and 1 had greater than 50% decrease. Allopurinol was most effective in patients with localization-related epilepsy, especially in secondarily generalized tonic-clonic seizures. Allopurinol was not as effective in patients with Lennox syndrome or West syndrome, or in severe myoclonic epilepsy in infants. When allopurinol was administered greater than 1 year, its initial effectiveness continued in 8 of 14 patients who exhibited initial improvement. In 2 of the remaining 6 patients, the initial improvement disappeared during the course of treatment but control was regained by increasing the dosage of allopurinol. Mild side effects were observed in 4 patients (13%): drowsiness in 3 and abdominal pain in 1. Allopurinol may be a useful antiepileptic drug (AED), and a double-blind placebo-controlled trial should be performed.

Adolescent↗