PubMed HealthSearch

Biomedical subjects

S Wakabayashi

Publications and source records attributed to S Wakabayashi.

At least 19 recordsLinked to original sources

[The effects of indigestible dextrin on sugar tolerance: I. Studies on digestion-absorption and sugar tolerance].

It is widely acknowledged that high viscosity water-soluble dietary fibers such as pectin and guar gum affect a lowering of blood glucose levels and a reducing of insulin secretion following a sugar load. However, as dietary fibers vary in origin and in chemical properties, their physiological functions differ as well. In this study the effects of Indigestible Dextrin (PF-C), a low viscosity, water-soluble dietary fiber obtained through acid and heat-treatment of potato starch, on various aspects of sugar tolerance were examined. First, the influence of PF-C on sucrose hydrolysis was examined in rat intestinal mucosa cell homogenate confirming that PF-C did not inhibit sucrase activity. Then, in order to investigate the influence of PF-C on sugar digestion-absorption, an experiment was performed by using the everted intestinal sac of the rat in vitro. PF-C did not have an effect on glucose-transport into the serosal medium, whereas PF-C did inhibit the transport of hydrolyzed-glucose from sucrose, with no change in the hydrolysis of sucrose. Recently, Crane et al. reported that there is a specific route for hydrolyzed glucose from sucrose in glucose-absorption on the enteric surface (disaccharidase related transport system). The possibility exists that PF-C specifically affects this pathway. Further, total glucagon released into the serosal medium stimulated by both glucose and sucrose were reduced by PF-C. On the basis of these results, an oral sugar tolerance test was conducted in both rats and healthy human subjects. In male Sprague-Dawley rats (8 weeks old, 250-280g) concurrent administration of PF-C (0.6g/kg body weight) reduced an increase in plasma insulin levels with no change in glucose levels following a glucose (1.5g/kg body weight) load. Further noted were reductions in increases in both plasma glucose and insulin levels following a sucrose (1.5g/kg body weight) plus PF-C (0.6g/kg body weight) load to that of the sucrose (1.5g/kg body weight) single load. These findings reflect the above mentioned in vitro results. Moreover, in healthy male subjects the increase in both plasma insulin and glucagon-like immunoreactivity (Gut GLI) levels following a Trelan-G75 load were significantly reduced by concurrent administration of PF-C. From these observations it would appear that the effectiveness of reducing insulin secretion by PF-C results due to the decrease in sugar absorption by inhibiting the disaccharidase-related transport system.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult

The Na+/H+ antiporter cytoplasmic domain mediates growth factor signals and controls "H(+)-sensing".

The amiloride-sensitive Na+/H+ exchanger (NHE1 human isoform) is activated in response to diverse mitogenic and oncogenic signals presumably through phosphorylation. To get insight into the activating mechanism, a set of deletion mutants within the C-terminal cytoplasmic domain of NHE1 has been generated. These mutant forms expressed in antiporter-deficient fibroblasts revealed that deletion of the complete cytoplasmic domain (i) preserves amiloride-sensitive Na+/H+ exchange and activation by intracellular H+, (ii) reduces the affinity of the internal "H(+)-modifier site" in a manner mimicked by cellular ATP depletion, and (iii) abolishes growth factor-induced cytoplasmic alkalinization. We conclude that NHE1 can be separated into two distinct functional domains. One is an N-terminal transporter domain (T) that has all the features required to catalyze amiloride-sensitive Na+/H+ exchange with a built-in H(+)-modifier site. The other is a C-terminal cytoplasmic regulatory domain (R) that (i) determines the set point value of the exchanger and (ii) mediates growth factor signals by interacting with the "H(+)-sensor" in a phosphorylation-dependent manner.

Animals

Atypical Moyamoya disease associated with brain tumor.

A 4-year-old boy with right retinal hemorrhage, mental retardation, and multiple minor anomalies was referred to our hospital. Computed tomography scanning revealed a cystic brain tumor at the vermis. Angiography showed stenosis of both internal carotid arteries at the supraclinoid portion and the Moyamoya vessels. The right ophthalmic artery was dilated as wide as the internal carotid artery. Stenosis of the basilar artery was also observed. Collateral circulation via the posterior inferior cerebellar artery and Moyamoya vessels in the area of the posterior cerebral artery was observed.

Abnormalities, Multiple

Induction of ovarian growth and ovulation by administration of a chicken gonadotrophin preparation to Japanese quail kept under a short-day regimen.

1. Chronic administration of a glycoprotein fraction from chicken pituitary using an ALZET osmotic pump at 12.5 micrograms/h for 2 weeks induced growth of ovarian follicles to a mature size in the ovary and deposition of yolk in sexually immature 6-week-old Japanese quail females which were kept under 8L:16D short-day conditions. However, no ovulation was induced in these birds. 2. Injection of 500 micrograms of the glycoprotein into other immature short-day females was performed following the above chronic administration, 12 or 14 and 15 d after implantation of the osmotic pump. About 24 h after injection, 3 of 14 females laid one or two eggs. Ovulation was confirmed in 4 females by autopsy. A total of 5 of 14 females ovulated 6 eggs, and significant development of the oviduct and the cloacal opening were observed in all of the treated females. 3. Thus, complete ovarian function could be induced in sexually immature female Japanese quail by administration of avian gonadotrophin using a combination of an osmotic pump and an injection.

Animals

New polyenic antibiotics active against gram-positive and gram-negative bacteria. VIII. Construction of synthetic medium for production of mono-chloro-congeners of enacyloxins.

New antibiotics enacyloxins (ENXs) are a family of non-lactonic polyene antibiotics produced by Frateuria sp. W-315. For the production of antibiotics, we had to employ two-step fermentations, the first is the production of spent medium of Neurospora crassa and the second is the production of antibiotics by Frateuria. To simplify the production of antibiotics, systematic analyses have been done on the spent medium, and factors which affect the production of antibiotics characterized. From the above results, we constructed a new medium for antibiotic production. Moreover, we could get a new antibiotic named enacyloxin IIIa (1), C33H48O11NCl (m/z 669). 1 was deduced to be one of the congeners of enacyloxins because it was similar to ENX IIa or ENX IVa both in biological and physico-chemical properties. Chlorine of 1 could be replaced by bromine, biosynthetically, and the resultant bromine-containing antibiotic also showed an antibacterial activity comparable to 1.

Acetobacteraceae

[Recurrent fusiform aneurysm of the internal carotid artery; a case report].

A 61-year-old woman was referred to our department on February 12, 1991, due to a fusiform aneurysm of her left internal carotid artery (ICA). She had received aneurysm surgery twice in other hospitals in the past. The first operation, in June, 1980, was for an unruptured, symptomatic left internal carotid-posterior communicating aneurysm and the aneurysm disappeared completely after the neck clipping procedure was carried out by one of the authors. In November, 1990, she suffered from subarachnoid hemorrhage with a hematoma in the left frontal lobe. A ruptured anterior communicating aneurysm was clipped in another hospital, where abnormal dilatation of the left ICA was pointed out. She was referred to our department after a ventricular peritoneal shunt operation. Though the postoperative angiogram performed in 1980 had shown complete disappearance of the left IC-PC aneurysm, it was presumed that the fusiform aneurysm which she presented at our department was recurrent because it existed in almost the same place as the aneurysm which had been clipped. It was also in contact with a clip applied in 1980. In accord with the patient's desire to receive surgery, the fusiform aneurysm was operated on directly, and it was remarkably reduced in size by dome clipping. During a clip, a Sugita booster clip was useful for preventing a slip-out of the clip applied on the aneurysmal dome. The patient was discharged about 20 days after the operation and returned to her usual life. A recurrent fusiform aneurysm of the ICA arising after the neck clipping of IC-PC aneurysm has rarely been encountered.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm

[A case of extraneural metastasis of medulloblastoma successfully treated with cisplatin and etoposide].

A patient who had been treated for cerebellar medulloblastoma presented progressive abdominal distension and tachypnea. Metastases of the tumor in the abdominal and thoracic cavity were confirmed by cytology. The authors treated the metastasis with a combination of intravenous administration of 20 mg/m2/day cisplatin and 60 mg/m2/day etoposide for two 5-day cycles. After chemotherapy, the patient recovered fully with time and follow-up radiological studies demonstrated no evidence of tumor recurrence. Combination chemotherapy with cisplatin and etoposide is to be considered effective for extraneural metastasis of medulloblastoma.

Antineoplastic Combined Chemotherapy Protocols

A large aneurysm of the persistent primitive hypoglossal artery.

An aneurysm of a persistent primitive hypoglossal artery (PHA) particularly at its junction with the basilar artery, often poses therapeutic problems. This is attributable not only to the size and location of the aneurysm but also to the fact that the persistent PHA is functionally the single artery providing blood in posterior circulation. We report a 31-year-old man with a large aneurysm of the persistent PHA at its junction with the basilar artery and review the existing literature. We clipped the broad neck of the aneurysm through a lateral suboccipital craniectomy; however, the patient suffered a second episode of subarachnoid hemorrhage. Angiography disclosed a slipped clip incompletely obstructing the persistent PHA. He received no further treatment for the aneurysm because of his deteriorating condition. Direct surgical treatment, although it failed to obliterate the aneurysm neck in our patient, should be recommended for a persistent PHA aneurysm.

Adult

Functional characterization of lanthanide binding sites in the sarcoplasmic reticulum Ca(2+)-ATPase: do lanthanide ions bind to the calcium transport site?

Gd3+ binding sites on the purified Ca(2+)-ATPase of sarcoplasmic reticulum were characterized at 2 and 6 degrees C and pH 7.0 under conditions in which 45Ca2+ and 54Mn2+ specifically labeled the calcium transport site and the catalytic site of the enzyme, respectively. We detected several classes of Gd3+ binding sites that affected enzyme function: (a) Gd3+ exchanged with 54Mn2+ of the 54MnATP complex bound at the catalytic site. This permitted slow phosphorylation of the enzyme when two Ca2+ ions were bound at the transport site. The Gd3+ ion bound at the catalytic site inhibited decomposition of the ADP-sensitive phosphoenzyme. (b) High-affinity binding of Gd3+ to site(s) distinct from both the transport site and the catalytic site inhibited the decomposition of the ADP-sensitive phosphoenzyme. (c) Gd3+ enhanced 4-nitro-2,1,3-benzoxadiazole (NBD) fluorescence in NBD-modified enzyme by probably binding to the Mg2+ site that is distinct from both the transport site and the catalytic site. (d) Gd3+ inhibited high-affinity binding of 45Ca2+ to the transport site not by directly competing with Ca2+ for the transport site but by occupying site(s) other than the transport site. This conclusion was based mainly on the result of kinetic analysis of displacement of the enzyme-bound 45Ca2+ ions by Gd3+ and vice versa, and the inability of Gd3+ to phosphorylate the enzyme under conditions in which GdATP served as a substrate. These results strongly suggest that Ln3+ ions cannot be used as probes to structurally and functionally characterize the calcium transport site on the Ca(2+)-ATPase.

Animals

The nirSTBM region coding for cytochrome cd1-dependent nitrite respiration of Pseudomonas stutzeri consists of a cluster of mono-, di-, and tetraheme proteins.

Genes for respiratory nitrite reduction (denitrification) of Pseudomonas stutzeri are clustered within 7 kbp. A 4.6-kbp Hind III-Kpn I fragment carrying nirS, the structural gene for cytochrome cd1, was sequenced. An open reading frame immediately downstream of nirS codes for a 22.8-kDa protein with four heme c-binding motifs. Mutagenesis of this gene causes an apparent defect in electron donation to cytochrome cd1. Following this ORF are the structural genes for cytochrome c552, cytochrome c551, and ORF5 that codes for a 11.9-kDa monoheme protein. All cytochromes have a signal sequence for protein export.

Amino Acid Sequence

Characterization of the vasoinhibitory actions of KT2-230, a new benzothiazepine vasodilator derivative on isolated rabbit vascular smooth muscles: an alpha-adrenergic- and serotonergic-receptor antagonist.

1. Pharmacological properties of KT2-230 (benzothiazepine derivative), a newly synthesized vasorelaxing agent, were studied. 2. In the anesthetized dogs, KT2-230 increased the femoral and vertebral blood flow without effect on systemic blood pressure. 3. In rabbit aorta, KT2-230, methysergide and phentolamine inhibited contractile responses to 5-hydroxytryptamine. 4. The response to norepinephrine was also inhibited by KT2-230 and phentolamine. Responses to histamine were not affected by KT2-230. 5. Responses to KCl and Ca2+ in K+ depolarized aorta in Ca2(+)-free medium were inhibited by a high concentration of KT2-230. 6. In rabbit iliac artery, KT2-230 inhibited the response to caffeine in Ca2(+)-free medium. 7. KT2-230 decreased total La3(+)-resistant Ca2(+)-binding at high affinity sites. 8. These results indicate that KT2-230 inhibits alpha 1-adrenoceptors and 5-HT-receptors and at high concentrations it inhibits slow Ca2(+)-channels. KT2-230 may inhibit the Ca2(+) release from caffeine- and agonist-sensitive Ca2+ stores.

Adrenergic alpha-Antagonists

Activation of sarcoplasmic reticulum Ca(2+)-ATPase by Mn2+: a Mn2+ binding study.

We used Mn2+ as an analogue for Mg2+ to examine the minimum requirement of divalent cations for the rapid turnover of the sarcoplasmic reticulum ATPase. We measured the binding of Ca2+ and Mn2+ to the purified Ca(2+)-ATPase during steady-state hydrolysis of MnATP at 2 degrees C and pH 7. In the presence of 20 microM Ca2+, Mn2+ was as effective as Mg2+ in stimulating ATPase activity and the maximal activation of ATP hydrolysis was observed at 0.1 mM MnCl2. Under these conditions, 2 mol of Ca2+ were bound per mol of the ADP-sensitive phosphoenzyme, whereas no Ca2+ was bound to the ADP-insensitive phosphoenzyme. On the other hand, the stoichiometry for ATP-dependent binding of Mn2+ to these intermediates was about 1. We found that Mn2+ remained bound to the ADP-insensitive phosphoenzyme even in the presence of added chelator. In the absence of ATP, we detected a low level of Mn2+ binding, which reached 0.4 mol per mol of the phosphorylation site at 0.1 mM free Mn2+. We present evidence that this extra Mn2+ binding did not affect the rate of decomposition of the ADP-sensitive phosphoenzyme, which was the rate-limiting step for ATP hydrolysis under the conditions used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate

The amino acid sequences of two 13 kDa polypeptides and partial amino acid sequence of 30 kDa polypeptide of complex I from bovine heart mitochondria: possible location of iron-sulfur clusters.

Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is the most complicated system in the respiratory chain. It consists of many subunits, some of which hold iron-sulfur clusters, but structural information is still limited. The amino acid sequences of two 13 kDa polypeptides, 13 kDa-A and 13 kDa-B polypeptides, of iron-sulfur protein fraction (IP) of bovine heart mitochondrial complex I were determined by a combination of protease digestion, Edman degradation, and carboxypeptidase digestion. The 13 kDa-A polypeptide was composed of 96 amino acids with a molecular weight of 10,536. The 13 kDa-B polypeptide consisted of 114 amino acids and had an acetylated amino terminus. The molecular weight of this protein was calculated to be 13,130 including the acetyl group. These proteins had no obvious sequence similarity to other known proteins. The partial amino acid sequence of 30 kDa-B polypeptide of IP was also determined to reveal a characteristic arrangement of cysteine residues that could be involved in iron-sulfur cluster formation.

Amino Acid Sequence

The amino acid sequence of the 9 kDa polypeptide and partial amino acid sequence of the 20 kDa polypeptide of mitochondrial NADH:ubiquinone oxidoreductase.

Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is the most complicated enzyme in the respiratory chain and is composed of at least 26 distinct polypeptides. Two hydrophilic subfractions of bovine heart complex I were systematically resolved into individual polypeptides by chromatography. Three polypeptides (51, 24, and 9 kDa) were isolated from the flavoprotein fraction (FP) of complex I, and the complete amino acid sequence of the 9 kDa polypeptide was determined. The 9 kDa polypeptide is composed of 75 amino acids with a molecular weight of 8,437. This protein exhibits no obvious sequence similarity to other proteins. The iron-sulfur protein fraction (IP) of complex I was separated into eight polypeptides, 75, 49, 30, 20, 18, 15, 13 kDa-A, and 13 kDa-B. The 20 kDa polypeptide was recognized as a novel component of IP for the first time. The N-terminal and several peptide sequences of the 20 kDa polypeptide were determined. Comparison of the sequences revealed significant sequence similarities of the 20 kDa polypeptide to the psbG gene products encoded in the chloroplast genome. The conserved sequence in these proteins was also found in the small subunit of the nickel-containing hydrogenases. These results suggest that complex I is related to other redox enzyme complexes.

Amino Acid Sequence

[Healing promoting effect of azuletil sodium (KT1-32) on experimental chronic gastric ulcers and acceleration of healing in SPF environment].

We examined the healing promoting effects of azuletil sodium on acetic acid and clamping cortisone-induced gastric ulcer in rats. For the experiments on clamping-cortisone gastric ulcer, we used not only conventional rats in conventional conditions but also specific pathogen free (SPF) rats on SPF environment in order to prevent infection. The following results were obtained. 1) In acetic acid ulcer, azuletil sodium (AZE) (greater than or equal to 90 mg/kg/day, p.o.) significantly decreased ulcer index. As estimated on the basis of stage analysis (Ulcer, Healing, Scar), AZE (greater than or equal to 30 mg/kg/day, p.o.) significantly promoted the healing of ulcers. 2) In clamping cortisone ulcer (conventional), AZE (100 mg/kg/day, p.o.) significantly promoted the regeneration of blood vessels. 3) In clamping cortisone ulcer (SPF), AZE at greater than or equal to 30 mg/kg/day and 100 mg/kg/day significantly increased the healing index and mucosal regeneration index, respectively. 4) In clamping cortisone ulcer (SPF), the infection that was observed in the conventional test was not seen at all and the acceleration of healing was observed. Furthermore, the extent of adhesion was also reduced, and the standard errors of various healing indices were smaller. From these results, it is concluded that AZE accelerated the healing of experimentally-induced gastric ulcers in rats.

Animals

Ring-enhanced primary intracranial malignant lymphoma--report of two cases.

Two nonimmunosuppressed patients with primary intracranial malignant lymphoma demonstrated ring-enhanced lesion on postcontrast CT scans. One patient underwent total removal of the tumor and the other patient biopsy, both followed by whole brain irradiation. Histological examination revealed the tumors contained diffuse large cells and necrosis in the central region. The possible mechanisms of ring enhancement may represent central necrosis of the rapidly growing tumor, but is probably not related to the prognosis.

Aged