Young-Duk Song

Insulin resistance and carotid atherosclerosis in patients with type 2 diabetes.

OBJECTIVEnInsulin resistance may provide a crucial link between type 2 diabetes and cardiovascular disease. However, it is still unclear whether insulin resistance itself or hyperinsulinemia is independently associated with subclinical atherosclerosis. We hypothesized that insulin resistance, but not hyperinsulinemia, would be associated with carotid atherosclerosis in patients with type 2 diabetes.nnnMETHODSnWe examined 2471 patients with type 2 diabetes, consecutively enrolled in Huh Diabetes Center. Insulin sensitivity was directly assessed by a rate constant for plasma glucose disappearance (Kitt) using short insulin tolerance test. Fasting insulin levels were used as a marker of hyperinsulinemia. Both carotid arteries were examined by B-mode ultrasound. Carotid atherosclerosis was defined by having a clearly isolated focal plaque or mean carotid intima-media thickness (IMT) >or=1.1mm.nnnRESULTSnIn multiple regression models, insulin sensitivity index (Kitt) but not hyperinsulinemia was significantly associated with carotid IMT adjusting for known risk factors such as age, sex, BMI, smoking, systolic pressure, HDL and LDL cholesterol. One standard deviation decrease in Kitt was associated with 0.046 mm increase in carotid IMT (p=0.015). Furthermore, odds ratio for carotid atherosclerosis was 1.43 (95% CI: 1.10, 1.86) in type 2 diabetic patients with insulin resistance (lowest quartile of insulin sensitivity) adjusting for known risk factors. The results were consistent in all subgroups stratified by sex, age, smoking and hypertension.nnnCONCLUSIONnInsulin resistance measured by short insulin tolerance test, but not hyperinsulinemia, is independently associated with carotid atherosclerosis in patients with type 2 diabetes.

Identification of glucokinase mutation in subjects with post-renal transplantation diabetes mellitus.

Mutations in the glucokinase (GCK) gene are considered to be a possible cause of maturity-onset diabetes of the young. The purpose of this study was to evaluate the contribution of this gene to the development of post-renal transplantation diabetes mellitus (PTDM). Identification of the GCK mutation was attempted in 58 selected renal allograft recipients with PTDM and 45 normal controls. The exons in the GCK gene were examined using polymerase chain reaction (PCR), followed by an analysis of single-stranded DNA conformational polymorphism (SSCP). The abnormal bands were then confirmed by DNA sequencing analysis. The family members of the patients affected with GCK mutation were also examined. Two of the 58 PTDM patients (3. 4%) were found to have GCK mutations. One had the mutation on exon 5 and the other on intron 7. One control subject had the mutation on intron 9. The mutation on exon 5 was identified as a substitution of CCT (proline) for CTT (leucine) at codon 164, which has never been reported before. The family members of the PTDM patient with a mutation on exon 5 were analyzed by PCR, followed by SSCP, and two of them had the same mutation. The abnormal band seen on SSCP analysis of exon 7 was identified as the C-->T substitution at the 39th nucleotide in intron 7. Two of the family members also displayed the same bands on the SSCP. One of the 45 normal controls had a known polymorphism located at the 8th nucleotide in intron 9. We found a GCK mutation on the exon in subjects with PTDM and we speculate that this mutation may be one of the possible contributing factors of PTDM, although variations of the GCK gene are not common causes of PTDM.

A study on the synthesis of spherical colloidal TPA-silicalite-1 using acidic promoters

Discrete spherical colloidal TPA-silicalite-1 with the gel composition 1.0TPAOH:3.0SiO 2 :100H 2 O:xPromoter (Promoter=H 2 SO 4 , HCl, HNO 3 and NH 4 OH, x=0-0.5) has been synthesized at 100°C. The spherical compounds modified as functions of acidic species and added promoter amount were fully investigated using PXRD, SEM, Light scattering, Zeta potential and 29 Si solid NMR. The mean sizes of H 2 SO 4 -induced TPA-silicalite-1 were ranged from 200 to 500nm and agreed with the results of the light scattering. The spherical morphology of the TPA-silicalite-1 was compared with a typical silicalite-1 with multiple twins and hillock. These facts suggest acidic promoter addition in TPA-silicalite enhanced the interaction of TPA + and the silica source, leading the effect of nucleation and crystallization, and led the preferred orientation of crystal growth due to regulate the shape of TPA-silicalite-1.