Preventive Effects of Green Tea (Camellia Sinensis var. Assamica) on Diabetic Nephropathy

PURPOSE: This study aimed to evaluate the preventive effects of Camellia sinensis var. assamica (CSVA) on diabetic nephropathy in in vitro and in vivo models. MATERIALS AND METHODS: MDCK cells were incubated with 1 mM of oxalate with or without different concentrations of CSVA, then MTT and malondialdehyde (MDA) assays were performed to investigate the preventive effects of CSVA on oxalate-induced cytotoxicity and oxidative stress. Thirty male db/db mice were divided into three groups. Group 1 were fed AIN-93G ad libitum; group 2 were fed AIN-93G mixed with 10% fermented CSVA ad libitum; group 3 were fed AIN-93G mixed with 10% non-fermented CSVA ad libitum. The mice were sacrificed 14 weeks later, and the serum glucose level, 24-hour urine chemistry, and morphological changes in the kidneys were examined. RESULTS: As CSVA concentrations increased, viable MDCK cells increased in concentration. MDA production decreased over time in the CSVA treated group. The creatinine clearance of group 3 was lower than those of groups 1 and 2. The amount of urine microalbumin and protein in group 1 were higher than those in groups 2 and 3. Also, more glomerulus basement membrane foot processes were preserved in groups 2 and 3. CONCLUSION: In conclusion, CSVA has beneficial preventive tendencies towards diabetic nephropathy in both in vitro and in vivo models.

Development of Recombinant Escherichia coli expressing oxc and frc Gene of Oxalobacter formigenes / 대한비뇨기과학회지

PURPOSE: Oxalobacter formigenes (O. formigenes) is an obligate anaerobe, which may be important in the prevention of stone formation. O. formigenes degrades oxalates using oxalyl-CoA decarboxylase and formyl- CoA transferase encoded by the oxc and frc genes, respectively. Attempts were made to develop recombinant Escherichia coli (E. coli) expressing both the oxc and frc genes of O. formigenenes. MATERIALS AND METHODS: After the extraction of total RNA from O. formigenes, a reverse transcriptase-polymerase chain reaction (RT-PCR) was carried out using primers synthesized according to the oxc and frc genes reported in GenBank. The cloned cDNA encoding oxalyl-CoA decarboxylase and formyl-CoA transferase was introduced into the pET-22b (+) plasmid vector. The constructs were verified by restriction analysis and DNA sequencing. The plasmid vector containing the cDNA fragment was transformed into competent E. coli BL21 (DE3). The recombinant E. coli was then analyzed using SD-SPAGE for the protein expressions of oxc and frc gene products, and visualized by staining with Coomassie Blue. RESULTS: Restriction enzyme and sequence analyses showed the gene cloned into the pET-22b (+) plasmid vector was identical to the reported oxc and frc genes. After the transformation into the competent E. coli, the SDS-PAGE analysis showed the recombinant E. coli expressed the proteins migrating at 66 and 50KD, which was identical to the reported weight of oxalyl-CoA decarboxylase and formyl-CoA transferase. CONCLISIONS: A recombinant E. coli, expressing oxc and frc genes, was successfully produced. Further studies may be necessary to investigate their enzymatic activities on the degradation of oxalate in the development of a new therapeutic strategy for the prevention of stone formation.

Association between Nanobacteria and Urinary Calcium Stone Disease / 대한비뇨기과학회지

PURPOSE: Nanobacteria have been reported to induce various pathologic calcifications like atherosclerosis and nephrolithiasis, and they do so by forming an apatite envelope, however, this concept is still controversial. We tried to elucidate whether nanobacteria might be related with urinary calcium stone by performing comparative study. MATERIALS AND METHODS: This study included 38 urinary stone patients who were proved to have calcium-containing stones and 37 healthy adults without urinary stone disease as controls. The subjects' age and gender were well matched between both groups. For the detection of nanobacteria, the serum and urine of all subjects were collected and western blotting for the samples was performed. RESULTS: There was no significant difference in the positive rate of nanobacteria from the serum samples between stone and control groups (52.6% vs 48.6%, respectively, p=0.465). But on the urine samples, the stone group showed a significantly higher positive rate than the control group (71.1% vs 21.6%, respectively, p<0.05). CONCLUSIONS: Nanobacteria might have a relation with urinary calcium stone disease.