PubMed Health⌕ Search

Biomedical subjects

N Asano

Publications and source records attributed to N Asano.

At least 109 records · Page 6Linked to original sources
PubMed1989

Preparation of 3-amino-3-deoxy derivatives of trehalose and sucrose and their activities.

The 3-keto derivatives of trehalose and sucrose respectively were prepared by a one-step enzymatic route using D-glucoside 3-dehydrogenase from Flavobacterium saccharophilum. Reductive amination of 3-ketotrehalose with ammonium acetate and sodium cyanoborohydride gave three compounds, 3-amino-3-deoxy-alpha-D-allopyranosyl alpha-D-glucopyranoside, 3-amino-3-deoxy-alpha-D-glucopyranosyl alpha-D-glucopyranoside (3-trehalosamine) and 3-amino-3-deoxy-alpha-D-mannopyranosyl alpha-D-glucopyranoside. From the reductive amination of 3-ketosucrose, 3-amino-3-deoxy-alpha-D-allopyranosyl beta-D-fructofuranoside and 3-amino-3-deoxy-alpha-D-glucopyranosyl beta-D-fructofuranoside were obtained. The antibiotic and glycohydrolase inhibitory activities of these 3-amino-3-deoxy derivatives were determined.

Amination↗
PubMed1989

[Multifocal gliomas in cerebral hemisphere associated with von Recklinghausen's disease: case report].

A case of intracerebral multifocal gliomas with von Recklinghausen's disease is reported. A 12-year-old boy was admitted to our hospital with an episode of convulsive attacks which were uncontrolled by anticonvulsants. CT scan and MRI revealed small well circumscribed tumors in the left frontal cortex and left parietal subcortex. Both of the tumors revealed low density in plain CT scan and low intensity in T1 weighted MRI. The vascularity of these tumors was poor in cerebral angiography. In other words these tumors were of a similar nature. The histology of the frontal tumor, which was totally removed surgically, showed typical pilocytic astrocytoma. The other tumor in the left parietal subcortex must also be included in the category of low grade glioma. In the sixth month after the operation, we could find neither recurrence of the frontal glioma nor enlargement of the parietal tumor, on CT and MRI findings. Immunohistochemically, the outer portion of the Rosenthal fiber in this tumor was positive for GFAP and S-100 protein, but the inner portion was negative, because the GFAP and S-100 protein there had degenerated. The cytoplasm of this tumor's cell was abundant with mitochondria and Golgi's bodies compared to the fibrillary astrocytoma. This case may be the first case of multifocal gliomas in the same cerebral hemisphere. We suggest that multifocal gliomas grow naturally, and over the years, tumors combine with each other and finally constitute a large type diffuse glioma.

Astrocytoma↗
PubMed1988

Physiological role of glucoside 3-dehydrogenase and cytochrome c551 in the sugar oxidizing system of Flavobacterium saccharophilum.

Flavobacterium saccharophilum cytoplasmic membranes contain several cytochromes linked to the respiratory chain. The presence of c-type cytochrome, cytochrome o, and a small amount of a-type cytochrome was proved. Cytochrome c551 was purified to electrophoretic homogeneity by ion-exchange chromatography and gel filtration from a membrane fraction of F. saccharophilum and its properties determined. Cytochrome c551 possessed absorption peaks at 407 nm in the oxidized form, and at 415, 521, 551 nm in the reduced form. The cytochrome c551 had a molecular weight of 15,500 as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Glucoside 3-dehydrogenase of F. saccharophilum reduced the cytochrome c551 with methyl-alpha-D-glucoside, D-glucose, sucrose, or validoxylamine A. When the purified glucoside 3-dehydrogenase was incubated with methyl-alpha-D-glucoside and purified ferricytochrome c551, methyl-alpha-D-3-ketoglucoside was formed as indicated by GC-MS analysis. The addition of a substrate to the membrane fraction caused an increase in the rate of oxygen uptake and an abrupt reduction in cytochrome c551. The electron transfer in the 3-keto sugar forming system may be as follows: sugars----glucoside 3-dehydrogenase----cytochrome c551----cytochrome oxidase----O2. Thus, the electron acceptor of glucoside 3-dehydrogenase is possibly connected to the membrane-bound cytochrome system.

Bacterial Proteins↗
PubMed1988

[Diurnal profile of gastrointestinal hormones following pancreatectomy].

A long-term follow-up study revealed that diabetes, diarrhea and dumping syndrome were the major complications after pancreaticoduodenectomy. The PABA recovery rate in PFD test was markedly decreased in patients with pancreaticoduodenectomy, suggesting that impaired exocrine pancreatic function is the main cause of the complications. A 24-hour profile of pancreatic juice secretion more than 1.5 months after operation, showed that pancreatic juice was rich in protein and amylase, and secretion was increased following a meal and early in the morning. Gastrin, CCK and VIP were not detected during these periods; however, secretin and motilin were increased. These results suggest that pancreatic exocrine function recovered in patients with pancreaticoduodenectomy and secretin and motilin played an important role in the regulation of these functions.

Circadian Rhythm↗
PubMed1987

The role of plasma secretin during starvation in dogs.

Plasma secretin levels were measured during a 72-hour starvation period in dogs. Plasma secretin rose significantly and insulin levels fell significantly during starvation. Intravenous glucose loading at the end of the 72-hour starvation period suppressed plasma secretin and free fatty acid levels with a concomitant rise of glucose and insulin levels. These findings suggest that secretin might be regulated by plasma glucose and insulin levels and might play a role in lipolysis during starvation.

Animals↗
PubMed1987

Intragastric migration of a ventriculoperitoneal shunt catheter.

A child developed bacterial meningitis and shunt dysfunction 2 years after the insertion of a ventriculoperitoneal shunt for posttraumatic hydrocephalus. The distal end of the shunt catheter had penetrated the gastric wall. We found no other report of intragastric shunt catheter migration with successful treatment.

Cerebrospinal Fluid Shunts↗
PubMed1987

Effect of validamycins on glycohydrolases of Rhizoctonia solani.

The pseudo-oligosaccharides, validamycins, showed potent inhibitory activity against trehalase of Rhizoctonia solani while no significant inhibition was exhibited against cellulase, pectinase, chitinase, alpha-amylase, alpha- and beta-glucosidases. In particular, validoxylamine A strongly inhibited trehalase in a competitive manner with a Ki value of 1.9 X 10(-9) M. The uptake of the antibiotic into the cell and the amount of the intracellular trehalose were investigated by incubating the washed mycelia of R. solani with validamycins. It was found that validamycin A is transported into the cell and hydrolyzed therein by a beta-glucosidase yielding validoxylamine A with greater inhibitory activity. Also validamycin A containing beta-D-glucosyl residue is more favorably taken up into the cell than validamycin D containing alpha-D-glucosyl residue or their common aglycone, validoxylamine A. In addition, validamycin A suppressed the in vivo degradation of the intracellular trehalose at very low concentration of 0.1 microgram/ml.

Anti-Bacterial Agents↗
PubMed1986

Synthesis and alpha-D-glucosidase inhibitory activity of N-substituted valiolamine derivatives as potential oral antidiabetic agents.

Various kinds of N-substituted valiolamine derivatives, including compounds 23a, 24a, and 34a, which are structurally analogous to the key pseudodisaccharides (25a and 26a) of naturally occurring oligosaccharide alpha-D-glucosidase inhibitors, have been synthesized and estimated by the measure of inhibitory activity against porcine sucrase and maltase. The N-substituted valiolamine derivatives evaluated in this study have been found to be more potent than the corresponding N-substituted valienamine derivatives as well as the parent valiolamine. It is noteworthy that even simple N-substituted valiolamine derivatives such as N-[2-hydroxy-1-(hydroxymethyl)ethyl]-, N-[(1R,2R)-2-hydroxycyclohexyl]-, and N-[(R)-(-)-beta-hydroxyphenethyl]valiolamine (6, 8a, and 9a) have the stronger alpha-D-glucosidase inhibitory activity against porcine intestinal maltase and sucrase than naturally occurring oligosaccharide alpha-D-glucosidase inhibitors.

Animals↗
PubMed1986

Purification and properties of glucoside 3-dehydrogenase from Flavobacterium saccharophilum.

A membrane-bound glucoside 3-dehydrogenase [EC 1.1.99.13], which oxidizes validoxylamine A to the 3-keto derivative, was solubilized from the membrane fraction of Flavobacterium saccharophilum by Triton X-100 and purified about 280-fold with an overall yield of 30% from the membrane fraction by column chromatography on DEAE- and CM-Sepharose CL-6B and gel filtration on Sephacryl S-300. The purified enzyme exhibited a single protein band on disc gel electrophoresis, and FAD was shown to be the prosthetic group. The enzyme had a molecular weight of 270,000 as determined by gel filtration on Sephacryl S-300 and consisted of 4 identical subunits each with a molecular weight of 66,000. The enzyme reacted with various artificial electron acceptors such as 2,6-dichlorophenolindophenol (DCIP), phenazine methosulfate, and ferricyanide. The optimum pH for DCIP reductase activity was 6.0. The enzyme was inhibited by Hg2+ and p-chloromercuribenzoate. D-Glucose and methyl-alpha- and beta-D-glucoside showed the highest susceptibility to the enzyme, and were converted to the corresponding 3-keto sugars.

Carbohydrate Dehydrogenases↗