Biomedical subjects

H Akanuma

Publications and source records attributed to H Akanuma.

At least 37 records · Page 2Linked to original sources

PubMed1992

Distribution of 1,5-anhydro-D-glucitol in normal, diabetic, and perfused rat bodies.

The concentration of 1,5-anhydro-D-glucitol (AG) was determined in various organs and tissues of normal rats and rats rendered diabetic with streptozocin, using an AG-assay method in which AG was extracted after acid hydrolysis of the whole tissues. The organs and tissues examined included skin, muscle, liver, and kidney. The plasma of control rats contained 3-12 micrograms/ml of AG. In these rats, all the organs examined also contained AG at concentrations not much lower than that in the corresponding plasma, except for adipose tissues and testis, which have relatively small water spaces; the latter two contained AG at relatively low concentrations. In contrast, both the plasma and various organs of the diabetic rats contained only trace amounts of AG. The whole body perfusion of control rats depleted AG from most of the organs, the exception being spleen, the circulation system of which is known to have a structure that is difficult wash by means of perfusion. These observations indicated that AG readily diffused into the inter- and intra-cellular water spaces from the circulation. Accordingly, the plasma membranes of the cells in these organs were suggested to be permeable to AG.

Animals↗

PubMed1992

Origin and disposal of 1,5-anhydroglucitol, a major polyol in the human body.

The origin and disposal of 1,5-anhydro-D-glucitol (AG), one of the main polyols found in the human body, was studied in normal subjects and diabetic patients. AG was detected in various kinds of foods. The mean AG supplement through foods was estimated to be approximately 4.38 mg/day, which was compatible with that calculated in a food analysis (average 0.22 mg AG/100 kcal in Japanese foods) on eight healthy subjects. The mean AG excretion in urine was approximately 4.76 mg/day in these subjects. Excretion into stools was negligible. From observations on the patients without oral supplement of AG, 0.4 mg of daily de novo synthesis of AG was strongly suggested. It was also implied that urinary AG excretion occurred soon after food ingestion and that its amount was closely correlated with daily supplement through foods. Thus the fundamental kinetics of AG were recognized as follows: 1) AG in the body originates mainly from foods and is well absorbed in the intestine, 2) AG is little degraded and metabolized in the body, and 3) an equilibrium exists between oral supplement plus a small but steady amount of de novo synthesis and excretion in urine.

Adult↗

PubMed1991

The primary structure of Aspergillus niger acid proteinase A.

The complete amino acid sequence of the acid proteinase A, a non-pepsin type acid proteinase from the fungus Aspergillus niger var. macrosporus, was determined by protein sequencing. The enzyme was first dissociated at pH 8.5 into a light (L) chain and a heavy (H) chain, and the L chain was sequenced completely. Further sequencing was performed with the reduced and pyridylethylated or aminoethylated derivative of the whole protein, using peptides obtained by digestions with Staphylococcus aureus V8 protease, trypsin, chymotrypsin, and lysylendopeptidase. The location of the two disulfide bonds was determined by analysis of cystine-containing peptides obtained from a chymotryptic digest of the unmodified protein. These results established that the protein consists of a 39-residue L chain and a 173-residue H chain that associate noncovalently to form the native enzyme of 212 residues (Mr 22,265). This is, to our knowledge, the first time that such a protein with a rather short peptide chain associated noncovalently has been found. No sequence homology is found with other acid or aspartic proteinases, except for Scytalidium lignicolum acid proteinase B, an enzyme unrelated to pepsin by sequence, which has about 50% identity with the present enzyme. These two enzymes, however, are remarkably different from each other in some structural features.

Amino Acid Sequence↗

PubMed1990

Mechanism for acute reduction of 1,5-anhydroglucitol in rats treated with diabetogenic agents.

The mechanism for acute reduction of plasma 1,5-anhydroglucitol (AG) in experimental diabetic rats was studied. Acute AG decrease was induced not only by diabetogenic agents, such as streptozotocin (STZ) and alloxan, but also by phloridzin, which caused glucosuria but not hyperglycemia. A similar reduction also occurred in hyperglycemia induced by glucose injection. The AG reduction induced by STZ was completely abolished by bilateral nephrectomy or by euglycemia with insulin treatment. The decrease of plasma AG was well correlated with the degree of urinary excretion of AG, which in turn reflected the degree of urinary glucose excretion, irrespective of the kind of agent causing the glucosuria. Under conditions of continuous glucose infusion, AG concentration decreased not only in plasma but also in various tissues and organs. The amount of AG lost was estimated to be almost equal to that excreted into urine during the period of infusion. These observations suggest that the degree of reduction of plasma AG depends simply on the urinary excretion of glucose, and it was assumed that the urinary excretion of 0.5 mg AG corresponds to the urinary excretion of 100 mg glucose during a short period after the onset of glucosuria.

Alloxan↗

PubMed1989

Calcium-induced localization of calcium-activated neutral proteinase on plasma membranes.

The location of calcium-activated neutral proteinase (CANP) was determined in human erythrocytes by crosslinking CANP to co-localizing proteins using a photolabeling bifunctional reagent, 4,4'-dithiobisphenylazide (DTBPA). The crosslinked products were selectively isolated by immunoprecipitation with a polyclonal anti-CANP antibody and analyzed by SDS-polyacrylamide gel electrophoresis after cleavage of the crosslinkage. In the calcium-free incubation medium the main proteins crosslinked with CANP were cytosolic proteins such as hemoglobin. In the presence of calcium ions, on the other hand, membrane skeletal proteins such as spectrin, band 4.1, 4.2 and 6 proteins as well as band 3 were crosslinked with CANP. Addition of calcium ionophore further increased the amount of crosslinked membrane proteins. These results suggest that in the absence of calcium ions CANP exists diffusely in the cytoplasm and is crosslinked with cytoplasmic hemoglobin nonspecifically while in the presence of calcium ions CANP associated with membrane where it is crosslinked specifically with the lining proteins. Thus it is demonstrated biochemically that the localization of CANP is dynamic depending on the presence of calcium ions.

Calcimycin↗

PubMed1989

Plasma 1,5-anhydro-D-glucitol as new clinical marker of glycemic control in NIDDM patients.

To elucidate the value of using plasma 1,5-anhydro-D-glucitol (AG) as a marker of glycemic control in diabetic patients, the relationship between the plasma concentration of AG and glucosuria was examined in 152 patients with non-insulin-dependent diabetes mellitus (NIDDM). After recovery from the deterioration of glycemic control in NIDDM patients had started, AG began to increase day by day. The recovery of plasma AG showed a constant linear increase curve when excellent glycemic control was attained. The ordinary daily recovery rate of plasma AG was estimated to be 0.3 microgram/ml, which was independent of body weight, sex, age, the difference in treatment, the duration of diabetes, or the level of plasma AG among NIDDM patients. This rate decreased according to the increase in urinary glucose. When we calculated the decrease rate of plasma AG (delta AG), assuming 0.3 microgram/day to be the maximum increase rate in a day, we found a high correlation between delta AG and urinary glucose at almost all AG levels except the normal range and observed that plasma AG (A) times urinary glucose (G) was relatively constant. The formula A x G = 16 is a simple equation for rough estimation of urinary glucose from the plasma AG concentration in a stable glycemic-controlled NIDDM patient, and we call it the A.G index. The plasma AG also correlated significantly with fasting plasma glucose (r = -.810) and glycosylated hemoglobin (r = -.856) in the same stable glycemic-controlled NIDDM patients. Based on these observations, we propose that plasma AG can serve as a new marker that may provide sensitive and analytical information about glycemic control.

Adult↗

PubMed1989

[A case of multiple peripheral hepatic artery aneurysms after chemoembolization].

A case of 57-year-old man with multiple peripheral hepatic artery aneurysms is reported. The patient was admitted with liver dysfunction and detected hepatoma in the right lobe. Chemoembolization was performed for the treatment of hepatoma. After 35 days, reangiography revealed multiple peripheral hepatic artery aneurysms in the region of chemoembolization. The etiology of aneurysms were presumably drug induced arteritis.

Aneurysm↗

PubMed1989

Changes in relationship between blood glucose level and plasma 1,5-anhydroglucitol level in KK mice.

We compared the relationship of the blood glucose level to the plasma 1,5-anhydroglucitol (1,5AG) level between KK mice with abnormal glucose metabolism and ICR mice as controls. Although the plasma 1,5AG level did not show any significant correlation with the blood glucose level in the controls, it tended to logarithmically decrease with the rise in the blood glucose level in KK mice. Thus it is possible that the plasma 1,5AG level is specifically related to the abnormal glucose metabolism in this model of diabetes mellitus and that its routine examination in diabetic patients may help delineate the metabolic derangement in the disease.

Animals↗

PubMed1989

Simple enzymatic method for determining 1,5-anhydro-D-glucitol in plasma for diagnosis of diabetes mellitus.

We have developed a simple method for determination of 1,5-anhydro-D-glucitol in plasma, based on use of pyranose oxidase (EC 1.1.3.10), an enzyme with specificity toward pyranoid compounds such as 1,5-anhydro-D-glucitol and glucose. Plasma samples deproteinized with trichloroacetic acid are passed through a two-layer mini-column packed with strongly basic anion (OH- form, the upper layer) and strongly acidic cation (H+ form, the lower layer) exchange resins. 1,5-Anhydro-D-glucitol is efficiently recovered in the flow-through fraction, which is almost devoid of other sugars that are sensitive to pyranose oxidase. The hydrogen peroxide formed in the enzymatic oxidation of 1,5-anhydro-D-glucitol is detected by a standard method utilizing an enzymatic color-developing system. The overall assay system is highly specific for 1,5-anhydro-D-glucitol. The correlation between results obtained in the present method (x) and in the gas-liquid chromatographic (GLC) method (y) was: y = 1.062x-0.293 mg/L (r = 0.997, n = 49, Sxy = 10.78 mg/L). Compared with GLC, our method is simpler in the sample treatment step and quicker in the measuring step. The precisions of the two methods are comparable.

Benzothiazoles↗

PubMed1988

Urinary excretion of 1,5-anhydro-D-glucitol accompanying glucose excretion in diabetic patients.

The urinary excretion of 1,5-anhydro-D-glucitol, a pyranoid polyol, in humans was studied. The plasma of nondiabetic human subjects contained high concentrations of this polyol (greater than 110 mumol/l), and there was a tendency for the 24-h excretion of it to become more variable in direct proportion to its plasma concentration. In contrast, diabetic patients showed lower plasma concentrations of this polyol, and the variation in the 24-h excretion of 1,5-anhydro-D-glucitol was especially notable among the patients with an extremely low plasma concentration of the polyol. This diabetic group showed a statistically significant correlation (p less than 0.01), between the urinary 1,5-anhydro-D-glucitol and urinary glucose. This correlation was more markedly demonstrated during a 100-g oral glucose tolerance test: parallel changes were observed in the concentrations of 1,5-anhydro-D-glucitol and glucose in the urine collected every hour after the glucose load. These observations led to the proposal that low plasma concentration of this polyol, which is observed in diabetes mellitus, may be the result of a frequent and/or prolonged high blood glucose concentration beyond the renal threshold for glucose excretion.

Adult↗

PubMed1988

Reduction of plasma 1,5-anhydroglucitol (1-deoxyglucose) concentration in diabetic patients.

The plasma concentration of 1,5-anhydro-D-glucitol(AG)(1-deoxyglucose) is known to decrease in diabetic patients. In order to evaluate the usefulness of this polyol as a diabetic marker, we examined the specificity of the plasma AG reduction in various diseases: the plasma AG level was determined in 108 newly diagnosed diabetic patients, 229 normal subjects and 200 patients with various other disorders. The mean plasma AG concentration in diabetes mellitus was 1.9 +/- 1.8 micrograms/ml (mean +/- SD), which was definitely lower than that in healthy subjects and patients with other diseases including some metabolic and hormonal diseases (mean value range: 13.4-28.3 micrograms/ml). Only the "malignancies" group showed statistically different mean values from that in normal subjects; however, these values were much higher than those of diabetic patients. The AG concentration seemed to be relatively low in some severe by uraemic patients, but is likely to be little influenced by the glomerular filtration rate. Upon adjustment for sex and age, AG concentration was not found to be correlated with the degree of obesity in both healthy subjects and diabetic patients. The plasma AG concentration showed a tendency to be higher in healthy males than in healthy females in all age-matched groups; however, statistically significant differences were not seen. Also, no significant influence of age was observed.

Adolescent↗

PubMed1988

Transport of 1,5-anhydro-D-glucitol across plasma membranes in rat hepatoma cells.

The transport of 1,5-anhydro-D-glucitol (AG) across plasma membranes was investigated in rat hepatoma cells, Reuber H-35. The AG uptake by the cells showed a concentration gradient dependency: the uptake was saturated within 40 s, which was less than one-third of the saturation time for 2-deoxy-D-glucose (DG) uptake. Furthermore, the Km value of the transport system for AG was higher than 100 mM. Though AG has a pyranoid structure resembling that of glucose, AG did not compete for cellular uptake with DG, D-glucose or 3-O-methyl-D-glucose, which are taken into cells through the glucose transporters. Conversely, the DG transport was not inhibited by AG at concentrations up to 50 mM. AG transport was hardly inhibited by 10 microM cytochalasin B, which strongly inhibits glucose transporters. In contrast, the AG transport was inhibited by 100 microM phloretin much more strongly than the DG transport when cells were preincubated with the inhibitor; the inhibition constant was 28.0 microM. The AG transport was not inhibited by 100 microM phloridzin, while the DG uptake was slightly inhibited by phloridzin. On the basis of these observations we propose that the AG uptake into rat hepatoma cells is mediated by a carrier distinct from glucose transporters.

Animals↗

PubMed1987

A unique specificity of a calcium activated neutral protease indicated in histone hydrolysis.

Calf thymus histones were found to be susceptible to a calcium-activated neutral protease [CANP: EC 3.4.22.17] which required a high concentration of calcium ions for its activity (mCANP). The susceptibilities of histones were in the order of relative degradation rate: H2B, H2A, and H3. The major peptide fragments released by CANP from H2A, H2B, and H3 were isolated and the cleavage sites were determined. Examination of amino acid sequences and environmental features around the cleavage site as well as kinetic analysis of the degradation process led us to the following conclusions about the mode of substrate recognition of mCANP: 1) The cleavage sites in histones could not be interpreted in terms of the primary structure around them. Thus, it seems unlikely that the specificity of CANP solely depends on its recognition of any specific amino acid residues or sequences. 2) The susceptible bonds were never located in the midst of either a hydrophobic or hydrophilic alignment of amino acid residues but in the vicinity of the boundary between hydrophilic and hydrophobic clusters. 3) Once a peptide fragment was generated by the proteolytic degradation, no further cleavage occurred even if the peptide still contained a bond corresponding to what was susceptible to CANP in an intact histone. This observation was interpreted to mean that CANP may recognize a certain higher order structure of its substrates.

Animals↗

PubMed1987

Reduced renal reabsorption of 1,5-anhydro-D-glucitol in diabetic rats and mice.

A stable amount, approximately 60 micrograms, of 1,5-anhydro-D-glucitol (AG) was detected in the 24-h-urine of normal young rats fed ad libitum. Upon administration of streptozotocin (STZ), this amount was temporarily elevated to as much as 1.1 mg and AG was concomitantly removed from the circulation. The plasma AG level stayed almost null thereafter while the acutely elevated urinary AG excretion declined within 24 h to another stable excretion level that was three times as high as that of the untreated rats. In contrast, glucosuria developed much more slowly in the drug-treated rats. Normal rats and mice retained exogenous [14C]AG to a considerable extent and the radioactivity was distributed all over the body. Only a marginal fraction of the radioactivity was excreted as expired CO2. The radio-activities retained in the body and excreted into the urine were mostly attributed to unmetabolized AG. The observations of AG's metabolic stability and its relatively low level of leakage into urine suggested the concept of effective renal AG reabsorption. On the other hand, the rats with STZ-induced diabetes and NOD-mice with spontaneously developed diabetes retained little of the radioactive AG in their bodies; most of the injected radioactivity was recovered in the urine within 24 h. This observation was interpreted as due to reduced renal AG reabsorption in these animals. The concept of reduction in renal AG reabsorption in diabetes could account for the reduced plasma AG level generally observed in human diabetic cases.

Absorption↗

PubMed1987

Reduction and recovery of plasma 1,5-anhydro-D-glucitol level in diabetes mellitus.

The plasma concentration of 1,5-anhydro-D-glucitol (AG) was measured in 135 newly diagnosed patients who were referred for oral glucose tolerance tests. AG concentrations in the nondiabetic patients indicated that the mean value of normal AG concentration was 21.8 micrograms/ml (SD = 5.9 micrograms/ml, range 9.6-38.8 micrograms/ml). This distribution of AG concentration was significantly different from that in patients with impaired glucose tolerance (IGT) (13.3 +/- 5.4 micrograms/ml) and definitely different from that in diabetic patients (2.1 +/- 1.8 micrograms/ml). In a standard glucagon test, it was suggested that the decrease of plasma AG was affected not only by glycemic control of the patients but also by pancreatic cell secretory activity. The reduction of AG concentration was more marked in IDDM patients than in NIDDM patients. In longitudinal studies, AG concentration was shown to be sensitive to glycemic control. However, its recovery showed a tendency toward much delay after the improvement of fasting blood glucose or HbA1 concentrations. On the other hand, AG concentration showed negligible diurnal change and no immediate change as a result of diet, oral glucose load, or acute shift of the insulin level in both normal and diabetic subjects.

Adolescent↗

PubMed1986

Oxidation of 1,5-anhydro-D-glucitol to 1,5-anhydro-D-fructose catalyzed by an enzyme from bacterial membranes.

Bacteria which grow on 1,5-anhydro-D-glucitol (AG) were isolated from soil. One such strain showing the highest AG-assimilating activity was further characterized and identified as a new strain of the Pseudomonas family (named Pseudomonas sp. NK-85001). A subcellular membranous fraction obtained from this strain catalyzed the oxidation of AG to 1,5-anhydro-D-fructose. This oxidation reaction consumed molecular oxygen as the terminal electron acceptor. The AG-oxidizing activity was further purified after solubilization. The AG oxidation catalyzed by this solubilized enzyme utilized molecular oxygen only in the presence of an electron mediator such as 2,6-dichlorophenolindophenol or phenazine methosulfate. Thus, the enzyme was suggested to be a dehydrogenase rather than an oxidase. The solubilized enzyme preparation also showed a strict substrate specificity. The observed specificity indicated that application of the enzyme for AG assay in clinical samples might be possible.

Cell Membrane↗

PubMed1986

Marked depletion of plasma 1,5-anhydroglucitol, a major polyol, in streptozocin-induced diabetes in rats and the effect of insulin treatment.

Plasma levels of 1,5-anhydroglucitol (1,5AG), a major polyol resembling glucose in structure, fell rapidly and dramatically in streptozocin (STZ)-treated rats. 1,5AG fell immediately after STZ injection, reaching a plasma level 6 h after administration of the drug that was one-third that in the plasma of control rats. Reduction of 1,5AG was independent of the profile of blood glucose induced by STZ. After intravenous injection of [14C]-1,5AG, its plasma half-life was determined to be between 120 and 180 min. After a phase of acute decrease, the reduction of 1,5AG became gradual, stopping within 6 days after treatment. However, in some cases, the drop in 1,5AG was partially reversible by insulin treatment. The extent to which 1,5AG fell did not strictly correspond to the dose of STZ. The particular organ(s) consuming or accumulating 1,5AG was not identified. However, aside from the large amount of 1,5AG in plasma and the small amount of 1,5AG in the urine, the liver appears to be a significant organ for metabolism of 1,5AG.

Animals↗

PubMed1985

Sorbitol determination by liquid chromatography: application to red blood cells of diabetic rats.

This report describes an application of liquid chromatography to the determination of sorbitol in red blood cells. The chromatograph employed in the present study was made up of sub- and main-separation systems and a detector portion. The sub-separation system was for concentration of polyols and involved two small columns, each containing the same anion exchange resin. The first was a tiny column which, in borate form, served as the concentrator of polyols and sugars charged in a large volume, while the second, in acetate form, separated the carbohydrates from the borate. The main system was for the fine separation of each carbohydrate and employed cation exchange columns. The detector part utilized a flow fluorometric method comprising two successive reactions: periodate oxidation followed by the Hantzsch reaction. The resulting whole chromatographic system was applied to the determination of sorbitol in red blood cells obtained from normal rats and rats made diabetic by the administration of streptozotocin; a part of the latter group had also received an aldose reductase inhibitor. Our results supported the concepts that a prolonged duration of high blood glucose level induces an elevated level of sorbitol inside red blood cells and that aldose reductase inhibitors are effective in reducing this level.

Aldehyde Reductase↗