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Biomedical subjects

M Kuwajima

Publications and source records attributed to M Kuwajima.

At least 109 records · Page 6Linked to original sources
PubMed1991

Low glucose-1, 6-bisphosphate and high fructose-2, 6-bisphosphate concentrations in muscles of patients with glycogenosis types VII and V.

The level of glucose-1, 6-bisphosphate, a potent allosteric activator of phosphofructokinase, was markedly decreased in muscles of patients with glycogenosis type VII (muscle phosphofructokinase deficiency) and type V (muscle phosphorylase deficiency). Glucose-1-phosphate kinase activity in muscle was virtually absent in a patient with glycogenosis type VII, whereas it was normal in a patient with type V glycogenosis. Glucose-1-phosphate level was increased in type VII glycogenosis, whereas it was decreased in type V glycogenosis. Another activator of phosphofructokinase, fructose-2, 6-bisphosphate was increased in muscles of patients with both types of glycogenosis although it was much higher in type VII than in type V. This finding may be partly related to the difference of fructose-6-phosphate concentrations. The results suggest that phosphofructokinase would contribute to the major glucose-1-phosphate kinase activity in normal human muscle and would also form a kind of self-activating system.

Fructosediphosphates↗
PubMed1991

Animal model of systemic carnitine deficiency: analysis in C3H-H-2 degrees strain of mouse associated with juvenile visceral steatosis.

We analyzed carnitine profiles in C3H-H-2 degrees strain of mouse associated with fatty liver, hyperammonemia and hypoglycemia (Koizumi et al., 1988). Carnitine levels in serum, liver and muscle of mouse with fatty liver were markedly decreased in comparison with those of control mouse (littermates without fatty liver). This is a useful animal model to analyze the role of carnitine in lipid, amino acid and carbohydrate metabolism.

Aging↗
PubMed1990

Tissue specificity in expression and alternative RNA splicing of human phosphofructokinase-M and -L genes.

Mode of the expression of phosphofructokinase (PFK) -M and -L genes was examined in various human tissues including muscle, placenta, liver, kidney, pancreas, stomach and reticulocytes. The gross level of mRNA expression of PFK-M and -L genes was estimated by Northern analysis. Polymerase chain reaction was used to detect mRNA expressed at low levels in these tissues. Tissue-specific expression of alternatively spliced PFK-M gene transcripts was also determined by polymerase chain reaction. The results indicated that alternative splicing of PFK-M gene transcripts was controlled in a tissue-specific manner.

Base Sequence↗
PubMed1990

Genetic defect in muscle phosphofructokinase deficiency. Abnormal splicing of the muscle phosphofructokinase gene due to a point mutation at the 5'-splice site.

The genetic defect in muscle phosphofructokinase deficiency (type VII glycogenosis, Tarui disease) was investigated. Six cDNAs for muscle phosphofructokinase, including a full-length clone, were isolated from a non-amplified library of muscle from a patient. By sequence analysis of these clones, a 75-base in-frame deletion was identified. The rest of the sequence was identical to that of the normal cDNA, except for a silent base transition at position 516 (ACT (Thr) to ACC (Thr]. The deletion was located in the 3'-terminal region of exon 13 (numbered with reference to the rabbit muscle phosphofructokinase gene (Lee, C.-P., Kao, M.-C., French, B.A., Putney, S.D., and Chang, S.H. (1987) J. Biol. Chem. 262, 4195-4199]. Genomic DNA of the patient was amplified by polymerase chain reaction. Sequence analysis of the amplified DNA revealed a point mutation from G to T at the 5'-end of intron 13. This mutation changed the normal 5'-splice site of CAG:GTATGG to CAG:TTATGG. A cryptic splice site of ACT:GTGAGG located 75 bases upstream from the normal splice site was recognized and spliced in the patient.

Base Sequence↗
PubMed1990

Glucose infusion abolishes the excessive ATP degradation in working muscles of a patient with McArdle's disease.

A 23-year-old woman with McArdle's disease performed mild leg exercise on a bicycle ergometer. Saline or 10% glucose solution was infused throughout exercise. After exercise with saline infusion, her plasma concentrations of ammonia, hypoxanthine and creatine kinase increased greatly. Conversely, after exercise with glucose infusion, there were no appreciable changes in these plasma substances. In addition, she noticed that glucose infusion relieved her from muscle symptoms during exercise. These findings suggest that glucose infusion to patients with McArdle's disease ameliorates excessive ATP degradation in exercising muscles.

Adenosine Triphosphate↗
PubMed1990

Compensatory capabilities of islets of BB/Wor rats exposed to sustained hyperglycemia.

To determine if discordance for autoimmune diabetes in genetically homogeneous animals might reflect differences in the compensatory capacity of their beta cells, the glycemic responses of diabetes-prone BB/Wor rats during a high rate infusion of 50% glucose were compared with normal and with 40% pancreatectomized Wistar rats similarly infused. In all three groups, the initially severe hyperglycemia declined after the first 48 hours to below the target level of 300 mg/dL despite an increasing rate of glucose infusion. The glycemic profile did not differ from controls and was lower than that of the partially depancreatized rats. Five of 20 hyperglycemic BB/Wor rats became diabetic during the 12-day infusion of 50% glucose; there was no difference between their glucose profiles and those of the 15 prediabetic BB/Wor rats that remained nondiabetic throughout the period of hyperglycemic infusion. The latter group of BB/Wor rats, many of which would ultimately have become diabetic, exhibited a 2.4-fold increase in the volume density of their beta cells, compared with a 2.1-fold increase in the Wistar controls. This clinical and morphologic evidence of beta-cell compensation in diabetes-prone rats, even in on the verge of overt diabetes, excludes the possibility that subnormal compensation by beta cells contributes to diabetes in the BB/Wor rat.

Adaptation, Physiological↗
PubMed1989

Autoantibodies to the insulin receptor impair clearance of plasma endogenous insulin.

Plasma insulin clearance was studied in a patient with autoantibodies to the insulin receptor, manifesting persistent hyperinsulinemia associated with alternating hyper- and hypoglycemia. In the postabsorptive period, the plasma glucose level gradually decreased. To prevent the development of hypoglycemia, glucose was infused and the glycemic level was clamped at 50 mg/dl without insulin infusion. The plasma C-peptide level was below the detectable range during the clamp, indicating no appreciable secretion of insulin. The plasma insulin level declined exponentially with a markedly prolonged disappearance rate (half-time: 3.0 h) during the study. These results indicate that hyperinsulinemia in the postabsorptive period in this patient is attributable to the impairment of plasma insulin clearance through receptor-mediated mechanisms, and also confirm that the receptor plays the principal role in plasma insulin removal.

Acanthosis Nigricans↗
PubMed1989

Microcomputer-assisted liquid chromatographic separation system: application to toxic compounds identification in poisoned human fluids.

The computer-assisted liquid chromatographic system (MCASYST) is developed for automated identification and analysis. The system has six main functions: retention prediction system, liquid chromatographic data base system, automated identification system, optimization of separation conditions, data loading program from UV multichannel detector, and UV spectral data base system. The performance and potential of this MCASYST system is evaluated for toxic compounds identification in poisoned human fluids.

Body Fluids↗
PubMed1989

Hyperinsulinemia due to impaired insulin clearance associated with fasting hypoglycemia and postprandial hyperglycemia: an analysis of a patient with antiinsulin receptor antibodies.

Antiinsulin receptor antibodies were detected in the serum of a patient with insulin-resistant diabetes. Fasting hypoglycemia and postprandial hyperglycemia recurred every day. The plasma insulin level was 553 +/- 359 pmol/L [77 +/- 50 microU/mL (mean +/- SD)] in the fasting state and rose above 7500 pmol/L postprandially. The glycemic clamp at 2.8 mmol/L (50 mg/dL) without insulin infusion revealed that the half-life of plasma endogenous insulin was 173 min, indicating severely impaired plasma insulin clearance. During the clamp the glucose infusion rate was almost constant (0.9-1.2 mg/kg.min) despite an exponential decline in the plasma insulin level from 460 pmol/L (65 microU/mL) to 129 pmol/L (18 microU/mL). Intravenous insulin administration did not appreciably accelerate the basal constant decrease in the plasma glucose level during the postabsorptive period. These results indicate the coexistence of marked insulin resistance and constant ability to decrease plasma glucose level. In in vitro experiments, antireceptor immunoglobulin G from this patient increased the fructose 2,6-bisphosphate concentration in the presence of glucagon (less than 0.1 nmol/L) in primary cultured rat hepatocytes. The antireceptor immunoglobulin G stimulated autophosphorylation of rat liver insulin receptor. We conclude that antiinsulin receptor antibodies could impair plasma insulin clearance, resulting in persistent hyperinsulinemia, and that continuous receptor stimulation by the antibodies was responsible for the development of hypoglycemia.

Animals↗