Insulin response to intravenous glucose injection in a family with a glucokinase mutation.
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Adult↗
Biomedical subjects
F Shimada
Publications and source records attributed to F Shimada.
Structure/function studies of human beta-cell glucokinase. Enzymatic properties of a sequence polymorphism, mutations associated with diabetes, and other site-directed mutants.
Glucokinase plays a key role in the regulation of glucose metabolism in insulin-secreting pancreatic beta-cells and in the liver. Recent studies have shown that mutations in this enzyme can lead to the development of a form of non-insulin-dependent diabetes mellitus that is characterized by an autosomal dominant mode of inheritance and onset during childhood. Here, we report the catalytic properties of five additional missense mutations associated with diabetes (Glu70-->Lys, Ser131-->Pro, Ala188-->Thr, Trp257-->Arg and Lys414-->Glu), one polymorphism present in both normal and diabetic subjects (Asp4-->Asn), and three site-directed mutations (Glu177-->Lys, Glu256-->Ala, and Lys414-->Ala). The Trp257-->Arg mutation generated an enzyme that had an activity that was less than 0.5% of that for native human beta-cell glucokinase. By contrast, the Glu70-->Lys, Ser131-->Pro, Ala188-->Thr, and Lys414-->Glu mutations had a Vmax that was 20-100% of normal but a Km for glucose that was 8-14-fold greater than the native enzyme. There was no effect of the Asp4-->Asn polymorphism or the Glu177-->Lys substitution on glucokinase activity. The Lys414-->Ala substitution had no effect on Vmax but increased the Km for glucose 2-fold and the Glu256-->Ala substitution caused a approximately 200-fold decrease in Vmax. These studies have led to the identification of additional residues involved in glucokinase catalysis and substrate binding.
Amino Acid Sequence↗
[A case of symmetric cerebral atrophy seen in both side of temporal lobe following spontaneous remission of encephalitis due to herpes simplex].
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Atrophy↗
Type 2 (non-insulin-dependent) diabetes mellitus associated with a mutation of the glucokinase gene in a Japanese family.
Mutations were screened for in the glucokinase gene of 25 Japanese patients with Type 2 (non-insulin-dependent) diabetes mellitus. Each exon was scanned by electrophoresis of enzymatically amplified DNA segments under non-denaturing conditions and variants were sequenced. A variant pattern was detected in exon 5 of one patient. Direct sequencing of this exon revealed a single nucleotide substitution in codon 188 (GCT-->ACT) of one of two alleles resulting in the mutation of Ala188-->Thr, an invariant residue in the sequence of all mammalian glucokinases and hexokinases. This mutation was not found in 40 normal control subjects. The proband had been diagnosed with Type 2 diabetes at the age of 62 years. Four other members of her family have the same mutation and all have Type 2 diabetes or impaired glucose tolerance. The youngest age at diagnosis of Type 2 diabetes in these other members was 13 years, suggesting that her pedigree was maturity-onset diabetes of the young (MODY). All subjects with the Thr188 mutation show a decreased insulin secretory response during oral glucose tolerance testing. Mutations in the glucokinase gene associated with Type 2 diabetes have been previously identified in Caucasian (French and British) subjects. This study indicates that mutations in this gene are also implicated in the development of Type 2 diabetes in Asians. Further studies are required to determine the frequency of mutations in glucokinase among Japanese patients with Type 2 diabetes.
Adolescent↗
Visualization of nasopharyngeal carcinoma with Tl-201 chloride and a three-head rotating gamma camera SPECT system.
Tl-201 SPECT was performed on 12 patients with nasopharyngeal carcinoma (NPC) by means of a three-head rotating gamma camera to evaluate whether or not Tl-201 SPECT was useful and reliable for assessing the tumor viability of NPC. Tl-201 clearly accumulated in the tumor in 3 patients before radiation treatment and increased Tl-201 uptake by the lesion ceased after the treatment. Three of 9 patients who were followed up after radiotherapy developed apparent local recurrence and Tl-201 SPECT clearly visualized these recurrent lesions. Tl-201 SPECT was very useful for assessing the tumor response to irradiation and for detecting local recurrent tumor. A high resolution SPECT system employing Tl-201 chloride is a new reliable and accurate diagnostic tool for the assessment of NPC.
Adult↗
A glycine-1008 to valine mutation in the insulin receptor in a woman with type A insulin resistance.
We examined the insulin receptor gene in a Japanese woman with type A insulin resistance. Acanthosis nigricans and polycystic ovary were present. A 75-g oral glucose tolerance test showed a diabetic pattern, and fasting insulinemia was 780 pmol/L. Insulin binding was normal, but autophosphorylation and tyrosine kinase activity were reduced in partially purified insulin receptors from Epstein-Barr virus-transformed lymphocytes. The nucleotide sequence for all 22 exons of the insulin receptor gene was determined by direct sequencing of genomic DNA amplified with the polymerase chain reaction. Substitution of valine for glycine at codon 1008 in the tyrosine kinase domain was identified in one allele. This was the same mutation found in another patient, but there was no relationship between the two families. The father had the same mutation in one allele and impaired glucose tolerance with mild hyperinsulinemia, but the mother and two brothers had normal glucose tolerance. We conclude that a single mutant allele in the tyrosine kinase domain caused the insulin resistance.
Adult↗
Possible involvement of ATP-sensitive K+ channels in the inhibition of rat central adrenergic neurotransmission under hypoxia.
By using rat brain cortical slices preloaded with [3H]norepinephrine, we examined whether ATP-sensitive K+ channels are involved in altered adrenergic neurotransmission during hypoxia. The tritium overflow evoked by transmural nerve stimulation (TNS) was significantly inhibited at 5 min of hypoxia and reached the maximum inhibition at 20 min. The inhibition of the TNS-evoked tritium overflow under a 20-min hypoxia was reversed by subsequent reoxygenation and was concentration-dependently antagonized by glibenclamide (0.1 and 1 microM). 86Rb+ efflux was increased after introduction of hypoxia and reached the peak value at about 20 min, which was concentration-dependently antagonized by glibenclamide (0.1-10 microM). Hypoxia decreased cortical ATP content. Linear correlations were mutually observed among the changes by hypoxia in the TNS-evoked tritium overflow, tissue ATP content and 86Rb+ efflux. The spontaneous tritium outflow was inhibited only after hypoxic periods of more than 16 min, the inhibition being reversed by reoxygenation and antagonized by 1 microM glibenclamide. These results suggest that the inhibition of rat central adrenergic neurotransmission during hypoxia may be associated with an activation of ATP-sensitive K+ channels.
Adenosine Triphosphate↗
Abnormal messenger ribonucleic acid (mRNA) transcribed from a mutant insulin receptor gene in a patient with type A insulin resistance.
In a previous report on a 16-year-old Japanese girl with type A insulin resistance, we found that one allele of the insulin receptor gene was inherited from her mother and contained a 1.2 kilobase pair deletion which removed the 14th exon in the beta subunit. We extended investigation of the proband and found the deletion between two Alu sequences. To determine the effect of the deletion on the level of transcription and the splicing pattern of messenger ribonucleic acid (mRNA), we synthesized the complimentary DNA and used the polymerase chain reaction to amplify the region which included the deleted area. The deletion shifted the reading frame, resulting in a termination codon after amino acid 867 (Glu), thereby producing a truncated insulin receptor without a transmembrane region and cytoplasmic domain. We also sequenced each of 22 exons of the insulin receptor gene but found no mutation in exons of the insulin receptor gene, except for deletion of exon 14 of the maternal allele. Thus, the proband is a heterozygote for a single mutant allele. Abnormal mRNA transcribed from the mutant allele resulted in a decrease in insulin binding.
Adolescent↗
Insulin receptor gene mutation: a molecular genetical and functional analysis.
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Diabetes Mellitus, Type 2↗
Studies on the enzyme immunoassay of bio-active constituents in oriental medicinal drugs. VI. Enzyme immunoassay of ginsenoside Rb1 from Panax ginseng.
Enzyme immunoassay (EIA) of ginsenoside Rb1 (GRb1), one of the glucosides of protopanaxadiol from Panax ginseng, was explored. A carrier protein (bovine serum albumin (BSA)) was coupled to the C-26 position on the unsaturated side chain of the protopanaxadiol moiety to prepare the immunogen. In order to perform bridge heterologous EIA, a label (beta-D-galactosidase) was introduced at C-26 of the saturated side chain to obtain labeled antigen. Anti-GRb1 antisera were elicited in rabbits by immunization with GRb1-BSA conjugate (9). The double antibody method (with goat anti-rabbit IgG antiserum) was used to separate the bound and free GRb1-beta-Gal. A satisfactory standard curve for EIA of GRb1 was obtained in the range of 0.04-10 ng/tube. In a comparison of the assay results obtained by EIA and HPLC, the linear regression equation and correlation coefficient for the two methods were y (EIA) = 9.18x(HPLC)-0.033 and 0.98, respectively. The anti-GRb1 antiserum cross-reacted with GRb2 (21.8%) and GRc (10.6%), which are also constituents of Panax ginseng.
Animals↗
Differential effects of diazoxide, cromakalim and pinacidil on adrenergic neurotransmission and 86Rb+ efflux in rat brain cortical slices.
The effects of diazoxide, cromakalim and pinacidil on depolarization-evoked tritium overflow from the rat brain cortical slices preloaded with [3H]noradrenaline were studied. Diazoxide inhibited both transmural nerve stimulation (TNS)- and 25 mM K(+)-evoked tritium overflows more potently than cromakalim. Diazoxide effects were only partially antagonized and cromakalim ones were totally reversed by 1 microM glibenclamide. Diazoxide, but not cromakalim, reduced the 45 mM K(+)-evoked tritium overflow, which was not antagonized by glibenclamide. Both diazoxide and cromakalim stimulated 86Rb+ efflux to a similar extent, the effects being completely abolished by glibenclamide. Glibenclamide (> or = 3 microM) by itself enhanced the TNS-evoked tritium overflow. Pinacidil increased both TNS- and K+ (25 and 45 mM)-evoked tritium overflows with little effect on 86Rb+ efflux. Pinacidil-induced increase in the TNS-evoked tritium overflow was still observed in the presence of cocaine or hydrocortisone. Pinacidil failed to affect the inhibitory action of xylazine on the TNS-evoked tritium overflow, whereas phentolamine attenuated it. These results indicate that ATP-sensitive K+ channels are present in the adrenergic nerve endings of rat brain. These channels seem to be pharmacologically different from those reported for vascular smooth muscles and pancreatic beta-cells.
Animals↗
[Assessment of skull base involvement of nasopharyngeal carcinoma by bone SPECT using three detectors system].
SPECT of the skull was performed on twelve patients with histologically proven nasopharyngeal carcinoma using newly developed three detectors SPECT system (Toshiba GCA 9300A) mounted with fan-beam collimators, for the purpose of early detection of skull base involvement of the disease. This SPECT system has extremely improved resolution with FWHM of 8 mm in the center, and it provides clear tomographic images of the skull which has anatomically complex structure. SPECT image was taken 3 hours after injection of 740 MBq (20 mCi) of 99mTc-MDP following whole body skeletal survey. In twelve patients with confirmed nasopharyngeal carcinoma, 8 patients showed positive findings on SPECT. Three of SPECT positive patients also showed destructive findings on CT. Other five positive patients did not show destructive findings on CT at their initial examinations, but in three of them CT findings turned to positive later. SPECT was superior to CT in early detection of skull base involvement. We believe that SPECT of the skull is a diagnostic tool for early detection of skull base involvement of nasopharyngeal carcinoma.
Adult↗
A cluster of four Sp1 binding sites required for efficient expression of the human insulin receptor gene.
Fragments of 5'-flanking sequences of the human insulin receptor gene were analyzed in transient expression assays after transfection of cell lines with expression assays after transfection of cell lines with an improved low background chloramphenicol acetyl-transferase vector system pSVOOCAT (Araki, E., Shimada, F., Shichiri, M., Mori, M., and Ebina, Y. (1988) Nucleic Acids Res. 16, 1627). Transfection of chimeric chloramphenicol acetyltransferase plasmids containing various deletions and insertions of the promoter of HIR gene into CHO and COS cells indicated that the region between -629 and -1 (initiator ATG is +1) is sufficient for maximal promoter activity. The DNA element of the cluster of four G-C boxes (-593 to -618) enhanced the transcription, examined by the low background pSVOOCAT vector system in vivo. DNase I footprinting and gel retardation experiments using partially purified LacZ-Sp1 hybrid proteins showed that the transcription factor Sp1 can bind to the cluster of the four G-C boxes of the promoter. Thus, the efficient expression of the human insulin receptor gene possibly requires the binding of transcriptional factor Sp1 to four G-C boxes located -593 to -618 base pairs upstream of the ATG translation initiation codon.
Animals↗
Defects in insulin binding and receptor kinase in cells from a woman with type A insulin resistance and from her family.
Defects in insulin receptor function lead to impairment of the insulin response. We treated a patient with the typical phenotype of type A syndrome of insulin resistance whose insulin receptor seemed to lack the transmembrane region and cytoplasmic domain. Hyperinsulinaemia and resistance to exogenous insulin were evident, and insulin binding to cells and uptake of 2-deoxyglucose into fibroblasts were greatly decreased. Molecular weight of the alpha-subunit of the insulin receptor was normal, but autophosphorylation and kinase activity were impaired. In the pedigree analysis, defects in insulin binding were also observed in the mother, maternal grandfather and two maternal aunts, corresponding with the abnormality of the insulin receptor gene and mild insulin resistance. In the mother, much the same kinase defects as were seen in the patient became evident. However, no relatives had clinical symptoms similar to those seen in the patient. In the father there was a mild insulin resistance in the glucose clamp study and a borderline impaired glucose tolerance. Although insulin binding to cells was normal in the father, both autophosphorylation and kinase activity were reduced. Our findings suggest that insulin resistance in the patient may be caused by the defects in insulin receptor kinase activity as well as by a reduction in insulin binding activity.
Adolescent↗
Relative inhibitory activity of berberine-type alkaloids against 12-O-tetradecanoylphorbol-13-acetate-induced inflammation in mice.
Forty eight derivatives of berberine-type alkaloids were examined for their inhibition activity against the induction of edema on mouse ear by application of 12-O-tetradecanoylphorbol-13-acetate (TPA). Berberine had an inhibitory effect against TPA-induced ear edema at a grade corresponding to those of quercetin, caffeine and cepharanthine. Berberine derivatives had stronger inhibitory activity than palmatine derivatives. 9-N,N-Diphenylcarbamoyl derivatives of both 9-demethylberberine and 9-demethylpalmatine had rather strong activity. These inhibitory activities are about ten times the activity of the respective mother compounds. Furthermore, 9-N-monophenylcarbamoyl derivatives and N,N-diphenylcarbamoyl chloride are found to have no effect.
Alkaloids↗
Effect of oral administration of glycyrrhizin on the pharmacokinetics of prednisolone.
The pharmacokinetics of total and free prednisolone (PSL) in six healthy men, with or without pretreatment with oral glycyrrhizin (GL), was investigated to confirm whether oral administration of GL influences the metabolism of PSL in man. Each subject received an intravenous administration of 0.096 mg/kg of prednisolone hemisuccinate (PSL-HS) with or without pretreatment with 50 mg of oral GL four times. Blood samples were taken from a peripheral vein at 5, 10, 15, 30, 45 min and 1, 1.5, 2, 3, 4, 6, 8, 10, 12 and 24 h after the start of PSL-HS infusion. The concentrations of total PSL in plasma were analyzed by high-performance liquid chromatography, and the free PSL was measured by an isocolloidosmolar equilibrium dialysis method. The pharmacokinetic parameters of PSL were determined by non-compartment analysis. Oral administration of GL was found to significantly increase the concentrations of total PSL at 6, 8 h, and of free PSL at 4, 6 and 8 h after PSL-HS infusion. Moreover, oral administration of GL was also found to modify the pharmacokinetics of both total and free PSL. After oral administration of GL, the area under the curve (AUC) was significantly increased, the total plasma clearance (CL) was significantly decreased, and the mean residence time (MRT) was significantly prolonged. However, the volume of distribution (Vdss) showed no evident change. This suggests that oral administration of GL increases the plasma PSL concentrations and influences its pharmacokinetics by inhibiting its metabolism, but not by affecting its distribution.
Administration, Oral↗
Insulin-resistant diabetes associated with partial deletion of insulin-receptor gene.
The insulin-receptor genes from a 16-year-old girl with type A insulin resistance, who presented with fasting hyperinsulinaemia, acanthosis nigricans, and reduced insulin binding, and from her family were examined. One allele of her insulin-receptor gene inherited from her mother contained a 1.2 kb deletion arising from a recombination between two Alu elements. The deletion removed the 14th exon in the beta subunit and altered the reading frame, to produce a stop codon after aminoacid 867. Pedigree analysis indicated that this mutation alone will not cause diabetes, and the proband is possibly a compound heterozygote. 4 other members of her family were heterozygous for the same mutation; all 4 had a decrease in insulin binding and slight impairment of glucose tolerance. Perhaps the same mutation is an underlying feature of some cases of non-insulin-dependent diabetes mellitus.
Adolescent↗
Effect of glycyrrhizin on the pharmacokinetics of prednisolone following low dosage of prednisolone hemisuccinate.
We investigated the pharmacokinetics of prednisolone (PSL) in six healthy men, with or without glycyrrhizin (GL), to confirm whether GL influences the metabolism of PSL in humans. Each subject received an intravenous administration of 0.096 mg/kg of prednisolone hemisuccinate (PSL-HS, equivalent to 0.075 mg/kg of PSL), with or without 200 mg of GL. Blood samples were taken from a peripheral vein at 5, 10, 15, 30 and 45 min, and 1, 1.5, 2, 3, 4, 6, 8, 10, 12 and 24 h after PSL-HS infusion. The concentration of total PSL in the plasma was analyzed by high-performance liquid chromatography, and the free PSL was measured by an isocolloidosmolar equilibrium dialysis method. The pharmacokinetic parameters of PSL were determined, using noncompartmental analysis. GL was found to increase significantly the concentration of total PSL at 6, 8 h, and of free PSL at 4, 6, and 8 h after PSL-HS infusion. GL was also found to modify the pharmacokinetics of PSL. After the administration of GL, the area under the curve (AUC) increased, total plasma clearance (CL) decreased, and the mean residence time (MRT) was prolonged. However, only those of AUC, CL, and MRT of free PSL were significantly different. The volume of distribution at a steady-state (Vdss) of both total and free PSL showed no evident change. This suggests that GL increases the plasma PSL concentrations by inhibiting the metabolism of PSL and that it potentiates pharmacological effects of PSL.
Adult↗