To elucidate the mechanism by which hyperuricemia develops in glycogen storage disease type I (GSD I), we studied seven patients with this disease. After an overnight fast hyproglycemia w a s associated with high plasma levels of oxypurines (hypoxanthine and xanthine). Administration of glucose(75g, p.o.) normalized these abnormalities as well as hyperglucagonemia, suggesting that hyproglycemia accelerates purine degradation in GSD I. Administration of either glucagon(lmg i.v.) or fructose(0.5g/kg body weight, p.o.) decreased the plasma inorganic phosphate level and increased the plasma oxypurine level, followed by elevation of serum uric acid levels. The urinary excretion of these purine metabolites were also increased. After maintaining normoglycemia by intravenous hyperalimentation therapy, hyperuricemia was cured. In addition,24-hour urinary excretion of uric acid was decreased, and the uric acid/creatinine clearance ratio was increased. Analyses of liver biopsy specimens from the patients revealed an incleased hexose monophosphate pool and low ATP levels accompanied by high AMP levels. These findings indicate that 1) not only decreased renal urate clearance but also enhanced hepatic purine degradation is responsible for the development of hyperuricemia in GSD I and 2)privention of hyproglycemia corrects these metabolic derangements.
Fifteen patients with primary gout who had a lipoprotein(a) levels over 20mg/dl were treated with 750mg/day of niceritrol to investigate its effect on serum concentration of lipoprotein (a), lipids and apolipoproteins. Niceritrol decreased the serum concentrations of lipoprotein (a), apolipoprotein B and triglyceride significantly( p<0.01, p <0.05, p <0.01 ), while it increased that of high-density lipoprotein cholesterol significantly(p<0.01). These findings suggested that niceritrol improved the lipoprotein(a) level as well as triglyceride and apolipoprotein B levels in patients with primary gout.
Gout is considered as an unusual disease in females. We analyzed the clinical features and laboratory tests in 43 female patients with gout. Of the female patients,20 (47%) had secondary gout, compared with 3 (5%) in the 60 age-matched male patients with gout. The secondary gout in females was associated with renal dysfunction and administration of diuretics. There were no signficant differences in other clinical features or laboratory tests between male and female patients. No differences were found in hormonal examinations compared with the female control group. Among a total of 543 patients with gout who visited our out-patient clinic in 1991,8 (1.47%)were females. This percentage was lower than tnat reported previously in Japan and that reported in other countries. These findings suggested a decrease in the fraction of female patients with gout, which might reflect the less frequent use of diuretics and/or the increase in the male patients with primary gout.
A 3.7 kb cDNA sequence encoding human erythrocyte type AMP deaminase (AMPD-3) has been determined by the screening of human spleen cDNA library and by some techniques utilizing polymerase chain reaction (PCR). The cDNA contains an open reading frame of 2301 by which encodes 767 amino acids chain resulting in 89 kDa protein. The homology to human muscle type AMP deaminase showed 64% identity at the nucleotide level in the area of open reading frame, and 60% similarity at the deduced amino acid level. From the analysis of the entire codi n g region of the mutant genes using RT-PCR and direct sequencing, a point mutation of C to T resulting in a single amino acid substitution of Arg to Cys was detected in both two B-cell lines derived from complete deficiency of human erythrocyte type AMP deaminase. The analysis for genomic DNA demonstrated that two individuals with complete deficiency were homozygous for the detected mutation, and two individuals with partial deficiency were heterozygous.