The core of allosteric motion in Thermus caldophilus L-lactate dehydrogenase.

For Thermus caldophilus L-lactate dehydrogenase (TcLDH), fructose 1,6-bisphosphate (FBP) reduced the pyruvate S(0.5) value 10(3)-fold and increased the V(max) value 4-fold at 30 °C and pH 7.0, indicating that TcLDH has a much more T state-sided allosteric equilibrium than Thermus thermophilus L-lactate dehydrogenase, which has only two amino acid replacements, A154G and H179Y. The inactive (T) and active (R) state structures of TcLDH were determined at 1.8 and 2.0 Å resolution, respectively. The structures indicated that two mobile regions, MR1 (positions 172-185) and MR2 (positions 211-221), form a compact core for allosteric motion, and His(179) of MR1 forms constitutive hydrogen bonds with MR2. The Q4(R) mutation, which comprises the L67E, H68D, E178K, and A235R replacements, increased V(max) 4-fold but reduced pyruvate S(0.5) only 5-fold in the reaction without FBP. In contrast, the P2 mutation, comprising the R173Q and R216L replacements, did not markedly increase V(max), but 10(2)-reduced pyruvate S(0.5), and additively increased the FBP-independent activity of the Q4(R) enzyme. The two types of mutation consistently increased the thermal stability of the enzyme. The MR1-MR2 area is a positively charged cluster, and its center approaches another positively charged cluster (N domain cluster) across the Q-axis subunit interface by 5 Å, when the enzyme undergoes the T to R transition. Structural and kinetic analyses thus revealed the simple and unique allosteric machinery of TcLDH, where the MR1-MR2 area pivotally moves during the allosteric motion and mediates the allosteric equilibrium through electrostatic repulsion within the protein molecule.

Case of Fusarium paronychia successfully treated with occlusive dressing of antifungal cream.

We report a case of refractory Fusarium paronychia in a 42-year-old man with Behçet's disease receiving oral cyclosporin and corticosteroid. Symptoms resembling candidal paronychia of his little finger could not be cured by topical ketoconazole and oral terbinafine. The pathogen was identified as Fusarium solani species complex by gene analysis, and was multiple drug resistant. The case eventually resolved by occlusive dressing therapy with 0.5% amorolfine cream for 3 months.

Serum uric acid as an obesity-related indicator in early adolescence.

In adults, serum uric acid levels are positively correlated with body mass index (BMI) and hyperuricemia is considered to be a common lifestyle disorder related with obesity. However, the relation of serum uric acid levels with obesity has not been elucidated in children and adolescents. Serum uric acid levels were determined in 1,729 healthy children, consisted of 923 boys and 806 girls, aged 9.1 - 15.0 years. The incidence of hyperuricemia (defined as more than 7.0 mg/dl) in boys and girls were 8.8% and 0.6%, respectively. In 1,281 children out of all subjects, including 684 boys and 597 girls, height, weight, aspartate aminotransferase, and alanine aminotransferase were also determined and the correlations between serum uric acid levels and obesity were analyzed. BMI is popularly used as a standard indicator of obesity in adults. However, BMI increases without fat accumulation as children grow. In Japan, percentage of overweight (POW) is usually used as an alternative indicator for obesity. In general, children are evaluated as obesity, when POW is equal to or more than 20% (>or= 20%). Serum uric acid levels are positively correlated with obesity-related indicators, BMI and POW, in both boys and girls. Serum uric acid levels of the subjects with high POW (>or= 20%) are significantly higher than those of the subjects with low POW (< 20%) in both boys and girls. These results suggest that serum uric acid levels are significantly increased with obesity and could be used as one of obesity-related indicators even in early adolescence.

No Improvement of Adult Height in Non-growth Hormone (GH) Deficient Short Children with GH Treatment.

It is still in doubt whether the standard-dose growth hormone (GH) used in Japan (0.5 IU/kg/week, 0.167 mg/kg/week) for growth hormone deficiency is effective for achieving significant adult height improvement in non-growth hormone deficient (non-GHD) short children. We compared the growth of GH-treated non-GHD short children with that of untreated short children to examine the effect of standard-dose GH treatment on non-GHD short children. GH treatment with recombinant human growth hormone (rhGH) was started before the age of 11 yr in 64 boys and 76 girls with non-GHD short stature registered at the Foundation for Growth Science who have now reached their adult height. In 119 untreated boys and 127 untreated girls whose height standard deviation score (SDS) was below -2 SD at the age of 6 yr, height growth was followed until 17 yr. Height SDS was significantly lower before GH treatment in the GH-treated group than at the age of 6 yr in the untreated group, in both sexes. Adult height and adult height SDS were significantly greater in the untreated group than in the GH-treated group, in both sexes, although the change in height SDS did not differ significantly. Height SDS was significantly lower before GH treatment in the GH-treated group than at the age of 6 yr in the untreated group, so 57 boys and 57 girls whose height SDS at the age of 6 yr in the untreated group closely matched the height SDS before GH treatment in the GH-treated group were chosen for comparison. Height SDS did not differ significantly between the GH-treated group before GH treatment and the untreated group at the age of 6 yr, nor were there differences between these subgroups in adult height, adult height SDS, or height SDS change, in either sex. The effect of GH treatment is reported to be dose-dependent and doses over 0.23 mg/kg/week are reported to be necessary to improve adult height in non-GHD short children. Currently, the GH dose is fixed at 0.175 mg/kg/week in Japan, and we expected to find, and indeed concluded, that ordinary GH treatment in Japanese, non-GHD short children does not improve adult height.

Recurrent URAT1 gene mutations and prevalence of renal hypouricemia in Japanese.

Recent identification of the urate transporter in the kidney (URAT1, encoded by SLC22A12) led to the molecular elucidation of idiopathic renal hypouricemia, which is a predisposition toward exercise-induce acute renal failure. One Japanese patient with renal hypouricemia demonstrated compound heterozygous mutations of the URAT1 gene (Q297X and IVS2+1G>A). It was suggested that these two mutations are recurrent mutations of the URAT1 gene in a Japanese population. In addition, we expect the prevalence of renal hypouricemia, 0.23%, from the analysis of serum urate levels in 1,730 Japanese children.