Type 2 diabetes mellitus: a high-risk condition for cardiovascular disease irrespective of the different degrees of obesity

BACKGROUND

Measurement of body weight with body mass index (BMI) is often utilized to stratify cardiovascular disease (CVD) risk.

AIM

To determine CVD risk profile and disease burden in subjects with type 2 diabetes mellitus (T2DM) across different categories of body weight as defined by BMI.

DESIGN

Prospective observational study.

METHODS

CVD risk including metabolic syndrome (MetS) and prevalence of macrovascular complications were determined for each category of body weight as defined by the World Health Organisation (WHO) classification.

RESULTS

A total of 390 subjects were included in this study of which 35.9% were non-obese (BMI <30 kg/m(2)). Although increasing obesity as defined by BMI was associated with higher prevalence of central abdominal obesity, hypertension and MetS (P < 0.05), dyslipidaemia and macrovascular complications were not significantly different across the various body weight categories (P = NS). Similar observation was seen in non-obese (BMI <30 kg/m(2)) and obese subjects (BMI >30 kg/m(2)). Among non-obese (including normal weight) cohort, the majority of these subjects had adverse CVD risk profile including presence of at least two co-existing risk factors.

CONCLUSION

Subjects with T2DM possess adverse CVD risk factors with significant burden of macrovascular disease irrespective of their baseline body weight.

Diagnosing metabolic syndrome in type 2 diabetes: does it matter?

BACKGROUND

Metabolic syndrome (MetS) is used as a clinical tool to identify individuals at risk of cardiovascular disease (CVD) but its clinical value in the management of type 2 diabetes mellitus (T2DM) remains uncertain.

AIM

To determine the prevalence and clinical usefulness of MetS among patients with T2DM attending diabetes clinics in a large teaching hospital.

DESIGN

Prospective observational study.

METHODS

Prevalence of MetS was determined by using International Diabetes Federation (IDF) and National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII) definitions in relation to age, sex, diabetes duration and history of CVD.

RESULTS

A total of 390 patients were included in this study. Both IDF and NCEP-ATPIII definitions identified high prevalence of MetS in male and female patients (IDF: male vs. female, 91.7 vs. 94.8% and NCEP-ATPIII: male vs. female, 87.6 vs. 94.2%) regardless of age (below vs. above 40 yrs, approximately 70-75 vs. approximately 90-95% with both definitions), diabetes duration (below vs. above 5 yrs, approximately 85-90 vs. 90-95% with both definitions) and history of CVD (without vs. with CVD, approximately 90 vs. approximately 95% with both definitions). Central obesity was common reflected by mean waist circumference of approximately 113 cm regardless of age and gender. Among those who did not have IDF-defined MetS, approximately 60% had at least two CVD risk factors. Both definitions similarly classified approximately 94% of the patients as either having or not having MetS.

DISCUSSION

Both definitions can be used interchangeably to diagnose MetS. However, the clinical usefulness of MetS is debatable given the very high prevalence of this condition in T2DM.

Retrospective multicenter study of a clinicopathologic analysis of pseudomyxoma peritonei associated with ovarian tumors (KGOG 3005)

The purpose of this study is to assess clinicopathologic features of pseudomyxoma peritonei (PMP) that has ovarian pathology and its relationship with the prognosis. From 1995 to 2004, the clinical records and follow-up data of 35 patients with PMP, which had primarily originated from the ovary, were collected from 11 institutes of gynecologic oncology in Korea and retrospectively analyzed. All patients had ovarian lesion histologically confirmed with PMP. The mean age at diagnosis was 53.7 years (range: 16-82 years). There were 25 (71.4%) patients with disseminated peritoneal adenomucinosis, 5 (14.3%) with peritoneal mucinous carcinomatosis with intermediate group, and 5 (14.3%) with peritoneal mucinous carcinomatosis. The clinical stages at diagnosis were IA in 2 patients, IIIB in 4, IIIC in 23, IV in 1, and unknown in 5. In preoperative tumor markers, the positive rates were 72% (CA125), 47.4% (CA19-9), and 84.6% (CEA). Thirty-four patients underwent surgical staging or cytoreduction, and then 27 patients (77%) received adjuvant chemotherapy that was given to patients in a nonuniform fashion. The 5-year survival for 35 patients was 87%. Survival rate was significantly lower in patients >50 years of age (P = 0.002). Our data showed that age of the patient is the only significant prognostic factor in PMP that has ovarian lesion.

The expression of epidermal growth factor receptor, vascular endothelial growth factor, matrix metalloproteinase-2, and cyclooxygenase-2 in relation to human papilloma viral load and persistence of human papillomavirus after conization with negative margins

The aim of this study was to investigate the correlations between human papillomavirus (HPV) load and vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR), matrix metalloproteinase-2 (MMP-2), and cyclooxygenase-2 (COX-2), and to identify biomarkers that may predict high-risk HPV clearance or persistence after conization with negative margins. The following samples were analyzed: 77 paraffin-embedded specimens from patients with cervical intraepithelial neoplasia (CIN), including 27 CIN 2 conization specimens and 50 CIN 3 conization specimens. Immunohistochemical analysis was performed with antibodies to VEGF, EGFR, MMP-2, and COX-2. Hybrid capture II testing was used to detect HPV DNA. VEGF expression was significantly associated with HPV load (ρ = 0.27186,P= 0.0191), while COX-2 expression was significantly and inversely associated with HPV load (ρ =−0.34309,P= 0.0028). In univariate analysis, HPV load (P= 0.0112) and VEGF expression (P= 0.0274) were significantly associated with high-risk HPV clearance or persistence after conization with negative margins. In multiple regression analysis, high viral load (relative light unit/positive control > 500) and positive VEGF expression were significantly associated with high-risk HPV persistence after conization with negative margins (odds ratio [OR]: 9.915, CI: 1.891–51.994; OR: 6.661, CI: 1.208–36.722, respectively). In conclusion, VEGF expression is related to HPV load, while COX-2 expression is inversely related to HPV load, and immunohistochemical analysis of VEGF expression and HPV viral load are a significant and an independent prognostic indicator of high-risk HPV persistence after conization with negative margins.

Finger-assisted stretching technique for cesarean section

OBJECTIVE

To compare the perioperative outcomes of two cesarean section methods, the finger-assisted stretching technique (FAST), based on a modified Joel-Cohen method, with the traditional technique.

METHODS

A retrospective review of the records of 416 women who underwent cesarean sections at Guro Hospital, Seoul, Korea, between May 1993 and December 2001 was performed. Of the 416 women, 283 underwent cesarean sections with FAST and 133 with the traditional technique.

RESULTS

Operative time was significantly shorter with FAST (15.3 vs. 42.6 min, P<.05), and FAST was associated with lower blood loss (601 vs. 928 mL, P<.05) and shorter hospital stay (3.7 vs. 6.5 days, P<.05). There were no significant differences in wound infection, voiding difficulty, and postoperative adhesions between the two methods.

CONCLUSION

These results suggest that FAST may be the better technique.

Neural prosthesis in the wake of nanotechnology: controlled growth of neurons using surface nanostructures

Neural prosthesis has been successfully applied to patients with motional or sensory disabilities for clinical purpose. To enhance the performance of the neural prosthetic device, the electrodes for the biosignal recording or electrical stimulation should be located in closer proximity to target neurons than they are now. Instead of revising the prior implanting surgery to improve the electrical contact of neurons, we propose a technique that can bring the neurons closer to the electrode sites. A new method is investigated that can control the direction of neural cell growth using surface nanostructures. We successfully guide the neurons to the position of the microelectrodes by providing a surface topographical cue presented by the surface nanostructure on a photoresponsive polymer material. Because the surface structure formed by laser holography is reversible and repeatable, the geometrical positioning of the neurons to microelectrodes can be adjusted by applying laser treatment during the surgery for the purpose of improving the performance of neural prosthetic device.

Coronary heart disease risk assessment in diabetes mellitus: comparison of UKPDS risk engine with Framingham risk assessment function and its clinical implications

AIMS

To assess differences between absolute coronary heart disease (CHD) risks calculated by Joint British Societies (JBS) risk calculator and UKPDS risk engine and its impact on CHD primary prevention management in diabetes mellitus (DM).

METHODS

Seven hundred Type 2 DM patients without arterial complications were identified from nine general practices in the Scarborough area. Their absolute 10-year CHD risks were calculated. The differences in the proportion of patients identified for aspirin and statin under JBS and National Institute for Clinical Excellence (NICE) guidelines by these two methods were determined. The proportion of additional patients identified for statin in the Scarborough population as a consequence of CHD risk threshold reduction from 30 to 15% (as recommended by NICE) was also determined.

RESULTS

UKPDS risk engine calculated significantly higher mean 10-year CHD risk (UKPDS vs. JBS, 21.5 vs. 18.3%, P < 0.0001). Both methods identified approximately 65% of patients to be eligible for aspirin and statin if NICE recommendations were followed. At a risk threshold of 30%, the UKPDS risk engine identified more patients for statin. Reducing the CHD risk threshold from 30 to 15% for statin initiation will identify an additional 0.5% of the total population for this treatment.

CONCLUSIONS

Both methods are comparable in identifying at-risk patients under NICE recommendations. A high proportion has risk levels that merits primary CHD prevention. Lowering the risk threshold for statin treatment has a small numerical impact on the whole population.

Cell uptake and tissue distribution of radioiodine labelled D-luciferin: implications for luciferase based gene imaging

Optical luciferase gene imaging is emerging as a method to monitor gene expression in small animals. However, there is concern over how regional availability of exogenously administered substrate may affect photon emission. We thus synthesized [125I]iodo-D-luciferin, which demonstrated substrate characteristics for firefly luciferase, and investigated its cell uptake kinetics and in vivo biodistribution. Luminescence assays of luc gene transduced cells confirmed a linear decline in emitted light units with decreasing luciferin concentration. Both luc gene transduced and control cells demonstrated a low level of cellular uptake and rapid washout of [125I]iodo-D-luciferin, although early uptake was slightly higher for transduced cells (P < 0.005). Biodistribution in ICR mice demonstrated that early uptakes in liver, lung, myocardium and muscle were lower with intraperitoneal compared to intravenous administration. In view of the poor cell uptake, uptake levels (< 3%ID/g) suggest that substrate concentration may limit light emission rates in organs such as bone, muscle, myocardium, and particularly the brain. Thus, substrate availability should be considered as a potential limiting factor for photon emission efficiency in certain organs when attempting quantitative interpretation of optical luc gene imaging.

Expressions of Multidrug Resistance-Related Genes in Gastric Cancer Tissue and Normal Gastric Mucosal Tissue

PURPOSE

This study was conducted to evaluate the expressions of the mdr1 gene and the MRP gene in tumor and adjacent normal gastric tissues.

MATERIALS AND METHODS

The specimens were obtained from 53 patients who had gastric cancer. None of these patients had received any kind of preoperative chemotherapy. The reverse transcription polymerase chain reaction and immunohistochemical stain were used to check the level of expressions of mRNAs and their associated proteins.

RESULTS

Highly positive expressions of mdr1 mRNA, MRP mRNA, p-glycoprotein, and MRP (multidrug resistance associated protein) were observed in the tumor and the adjacent normal tissues. Most tumor tissues coexpressed mdr1 mRNA and MRP mRNA significantly (p<0.001). The expression of these genes in the tumor was much stronger than in the normal counterpart tissues. The expression of the p-glycoprotein was correlated only with the pathological stage (p<0.05). MRP expression was correlated with lymph node metastasis (p<0.05).

CONCLUSION

Normal gastric tissue showed strong physiologic expressions of the mdr1 and MRP genes. Overexpressions of these genes were observed in gastric cancer tissue. The presence of multidrug resistance should be considered when planning anticancer chemotherapy for treating gastric cancer.

DNA transfection using linear poly(ethylenimine) prepared by controlled acid hydrolysis of poly(2-ethyl-2-oxazoline)

A series of linear poly(ethylenimine) (L-PEI) containing varying amounts of cationic charge density in its backbone was produced by controlled hydrolysis of poly(2-ethyl-2-oxazoline) (PEtOz) for using as a nonviral DNA transfection agent. The effects of cationic charge density and molecular weight of the L-PEI on the cytotoxicity and transfection efficiency were studied. The efficiency of transfection was monitored by using a luciferase reporter gene system. Gel retardation assay and dynamic light scattering (DLS) showed that the condensation capacity of L-PEI was suitable for transfection. Highly compacted L-PEI/DNA complex ( approximately 150 nm) was obtained with a surface charge value of around +28.4 mV. Cell cytotoxicity was affected to a great extent by the hydrolysis percent of L-PEI as well as by the molecular weight. Transfection efficiency of luciferase plasmid DNA against NIH 3T3 fibroblast was largely dependent upon the hydrolysis percent (charge density) in the polymer backbone and the molecular weight of the L-PEI, but independent of the total amount of cationic charges used for DNA condensation. L-PEI with a hydrolysis percent of 88.0% exhibited comparable transfection efficiency to that of commonly used branched PEI.

Transcriptional silencing of Cyclooxygenase-2 by hyper-methylation of the 5' CpG island in human gastric carcinoma cells

It has been well established that overexpression of Cyclooxygenase-2 (Cox-2) in epithelial cells inhibits apoptosis and increases the invasiveness of malignant cells, favoring tumorigenesis and metastasis. However, the molecular mechanism that regulates Cox-2 expression has not been well defined in gastric carcinoma. In this study, we examined whether the Cox-2 expression could be regulated by hyper-methylation of the Cox-2 CpG island (spanning from -590 to +186 with respect to the transcription initiation site) in human gastric carcinoma cell lines. By Southern analysis, we found that three gastric cells (SNU-601, -620, and -719) without Cox-2 expression demonstrated hyper-methylation at the Cox-2 CpG island. A detailed methylation pattern using bisulfite sequencing analysis revealed that all of the CpG sites were completely methylated in SNU-601. Treatment with demethylating agents effectively reactivated the expression of Cox-2 and restored IL-1beta sensitivity in the previously resistant SNU-601. By transient transfection experiments, we demonstrate that constitutively active Cox-2 promoter activities were exhibited even without an exogenous stimulation in SNU-601. Furthermore, when the motif of the nuclear factor for interleukin-6 expression site, the cyclic AMP response element, or both was subjected to point mutation, the constitutive luciferase activity was markedly reduced. In addition, Cox-2 promoter activity was completely blocked by in vitro methylation of all of the CpG sites in the Cox-2 promoter region with SssI (CpG) methylase in SNU-601. Taken together, these results indicate that transcriptional repression of Cox-2 is caused by hyper-methylation of the Cox-2 CpG island in gastric carcinoma cell lines.

Expression and characterization of a recombinant Fab fragment derived from an anti-human alpha-fetoprotein monoclonal antibody

Alpha-fetoprotein (AFP) is a well-known molecular marker indicating the development of cancer as well as fetal abnormalities such as open neural tube defects. Accordingly the measurement of serum AFP is important for the diagnosis of hepatocellular carcinoma (HCC) and other abnormalities. Monoclonal antibodies (McAb) to AFP were produced to develop an immunoassay kit, and to study the possibility of an antibody (Ab) therapy. The immunoglobulin genes were cloned from hybridoma cells, and expressed in E. coli as an Fab soluble into a culture medium. The Fab of anti-AFP McAb exhibited binding to AFP and similar affinity compared to the original IgG. This recombinant antibody can be studied further for in vivo imaging and immunotherapeutics.

Study on mechanism of multistep hepatotumorigenesis in rat: development of hepatotumorigenesis

With the aim of establishing bio-indices for the development of multistep hepatotumorigenesis, rats were fed water containing 0.01% diethylnitrosamine (DEN) ad libitum for 13 weeks. This treatment with DEN only made it possible to induce hepatic tumors in 100%. After the DEN administration, several clinical symptoms were observed including minor behavioral changes, brittleness of hair and a decrease in water and food intake. The concentration of total serum protein and albumin in all treated groups was significantly lower than in non-treated controls (P<0.05). Increase of specific enzyme (AST, ALT and GGT) activity (P<0.05), variable tumor size and hepatomegaly of the liver was observed in all rats treated with DEN for 10 weeks. Both hepatocellular carcinoma and cholangiocarcinoma were found in the same livers at the same time, and were prominently developed after 12 weeks. In case of carcinoma, some of the livers showed more or less advanced states over the 12-15 weeks period. In the present study, hepatocellular carcinoma was developed by treating DEN in only the drinking water, without any other carcinogens or without partial hepatectomy. These results indicate that DEN is a new carcinogen that acts directly on it the liver, moreover, it might be very useful for investigating hepatotumorigenesis.

Direct measurement of pulsatile insulin secretion from the portal vein in human subjects

Insulin is secreted in a high frequency pulsatile manner. These pulses are delivered directly into the portal vein and then undergo extraction and dilution before delivery into the systemic circulation. The reported frequency of these insulin pulses estimated in peripheral blood varies from an interpulse interval of 4-20 min. We postulated that this discrepancy is due to the attenuation of the pulse signal in the systemic circulation vs. the portal circulation. In the present study we measured pulsatile insulin release directly in the portal circulation of human subjects who had indwelling transjugular intrahepatic portasystemic stent shunts (TIPSS) to decompress portal hypertension. We quantitated pulsatile insulin secretion in both the overnight fasted state (fasting) and during a hyperglycemic clamp (8 mmol/L). Direct portal vein sampling established that pulsatile insulin secretion in humans has an interval (periodicity) of approximately 5 min. The amplitude (and mass) of the insulin concentration oscillations observed in the portal vein was approximately 5-fold greater than that observed in the arterialized vein and was similar to that observed in the dog. Increased insulin release during hyperglycemia was achieved through amplification of the insulin pulse mass. In conclusion, direct portal vein sampling in humans revealed that the interpulse interval of insulin pulses in humans is about 5 min, and this frequency is also observed when sampling from the systemic circulation using a highly specific insulin assay and 1-min sampling, but is about 4-fold greater than the frequency observed at this site using single site RIAs. We confirm that enhanced insulin release in response to hyperglycemia is achieved by amplification of these high frequency pulses.

Amorpha-4,11-diene synthase of Artemisia annua: cDNA isolation and bacterial expression of a terpene synthase involved in artemisinin biosynthesis

Artemisia annua, an indigenous plant to Korea, contains an antimalarial sesquiterpene, artemisinin. The first committed step of artemisinin biosynthesis is the cyclization of farnesyl diphosphate by a sesquiterpene synthase to produce an amorphane-type ring system. The aims of this research were to molecularly clone and express amorpha-4,11-diene synthase for metabolic engineering. PCR amplification of genomic DNA with a pair of primers, designed from the conserved regions of sesquiterpene synthases of several plants, produced a 184-bp DNA fragment. This fragment was used in Northern blot analysis as a probe, showing approximately 2.2 kb of a single band. Its sequence information was used to produce 2106 bp of a full-length cDNA sequence including 1641 bp of open reading frame for 546 amino acids (kcs12) through a rapid amplification of cDNA ends (RACE). The deduced amino acid sequence displayed 36% identity with 5-epi-aristolochene synthase of Nicotiana tabacum. A soluble fraction of Escherichia coli harboring kcs12 catalyzed the cyclization of farnesyl diphosphate to produce a sesquiterpene, which was identified through GC-MS analysis as amorpha-4,11-diene.

Lysozyme microencapsulation within biodegradable PLGA microspheres: urea effect on protein release and stability

Lysozyme was encapsulated within biodegradable poly(D, L-lactide-co-glycolide) microspheres by a double emulsion solvent evaporation method for studying its release mechanism associated with protein stability problems. When urea, a protein unfolding agent, was added into the incubation medium lysozyme release rate from the microspheres increased with the increase in urea concentration. The enhanced lysozyme release was attributed to the suppression of protein aggregation, to the facilitated diffusion of unfolded lysozyme by an efficient reptile motion of unfolded protein molecules through porous channels in microspheres, and to the largely decreased extent of nonspecific protein adsorption onto the enlarged surface area of degrading polymer microspheres in the presence of urea. Encapsulating lysozyme in an unfolded form within PLGA microspheres was attempted by using urea as an excipient. This new urea-based formulation exhibited a more sustained lysozyme release profile than the control formulation, and released lysozyme from the microspheres showed a much less amount of lysozyme dimer population while maintaining a correct conformation after refolding in the incubation medium. This study provides new insights for the formulation of protein encapsulated PLGA microspheres.

Methylation of specific CpG sites in the promoter region could significantly down-regulate p16(INK4a) expression in gastric adenocarcinoma

Silencing of p16(INK4a) by methylation of the CpG islands in the promoter region has been found to be an alternative mechanism of inactivation in several tumors. However, in gastric carcinoma, the relationship between methylation status and the transcriptional silencing of the p16 gene remains to be clarified. In this study, we investigated whether methylation of a few specific CpG sites in the promoter region could significantly down-regulate p16 activity in the tumorigenesis of gastric carcinoma. By Southern analysis and bisulfite-modified genomic sequencing of 9 gastric-carcinoma cell lines, we found that the 5 cell lines (55.5%) not expressing p16 mRNA had methylated CpG sites at the promoter region of p16. In addition, we analyzed the p16-protein expression of 28 primary gastric carcinomas and their normal counterparts by immunohistochemical staining (IHC) on paraffin sections. Loss of p16 expression was detected in 6 cases (22%). In 5 out of these 6 (83%), the actual p16 gene was inactivated by de novo methylation of the promoter sites. Taken together, these results suggest a strong correlation between de novo methylation of a few specific CpG sites and transcriptional silencing of the p16 gene in gastric carcinoma.

Methylation of specific CpG sites in the promoter region could significantly down-regulate p16(INK4a) expression in gastric adenocarcinoma

Silencing of p16(INK4a) by methylation of the CpG islands in the promoter region has been found to be an alternative mechanism of inactivation in several tumors. However, in gastric carcinoma, the relationship between methylation status and the transcriptional silencing of the p16 gene remains to be clarified. In this study, we investigated whether methylation of a few specific CpG sites in the promoter region could significantly down-regulate p16 activity in the tumorigenesis of gastric carcinoma. By Southern analysis and bisulfite-modified genomic sequencing of 9 gastric-carcinoma cell lines, we found that the 5 cell lines (55.5%) not expressing p16 mRNA had methylated CpG sites at the promoter region of p16. In addition, we analyzed the p16-protein expression of 28 primary gastric carcinomas and their normal counterparts by immunohistochemical staining (IHC) on paraffin sections. Loss of p16 expression was detected in 6 cases (22%). In 5 out of these 6 (83%), the actual p16 gene was inactivated by de novo methylation of the promoter sites. Taken together, these results suggest a strong correlation between de novo methylation of a few specific CpG sites and transcriptional silencing of the p16 gene in gastric carcinoma.

Chronological effects of atherogenic diets on the aorta, liver and spleen of rabbits

To investigate the temporal progression of atherogenesis on the aorta and involvement of the monocyte-macrophage system in the liver and spleen, we fed 74 rabbits with high fat (14 or 7 gm%) and cholesterol (2 and 1%) diets for 4 to over 24 weeks. Using both light and electron microscopies, we found that the fibro-fatty areas on the luminal surface of aortas was spread over along the feeding time dependently. The fat deposits also in the liver and spleen worsened depending on the time of feeding the atherogenic diets. Not only monocyte-derived foam cells, but also parenchymatous cells in the liver and spleen involved become fat-laden cells. According to these results, we propose that there are three stages: 1) the primary seeding, 2) the intermediate maturing and 3) the advanced periods. These periods may play very important roles in designing the management and treatment of atherosclerotic patients.

Effects of solvent selection and fabrication method on the characteristics of biodegradable poly(lactide-co-glycolide) microspheres containing ovalbumin

To demonstrate the effect of formulation conditions on the controlled release of protein from poly(lactide-co-glycolide) (PLGA) microspheres for use as a parenteral drug carrier, ovalbumin (OVA) microspheres were prepared using the W/O/W multiple emulsion solvent evaporation and extraction method. Methylene chloride or ethyl acetate was applied as an organic phase and poly(vinyl alcohol) as a secondary emulsion stabilizer. Low loading efficiencies of less than 20% were observed and the in vitro release of OVA showed a burst effect in all batches of different microspheres, followed by a gradual release over the next 6 weeks. Formulation processes affected the size and morphology, drug content, and the controlled release of OVA from PLGA microspheres.

Modulation of renal xanthine oxidoreductase in aging: gene expression and reactive oxygen species generation

Xanthine oxidoreductase (XD: xanthine dehydrogenase + xanthine oxidase) is a complex enzyme that catalyzes oxidation of hypoxathine to xanthine, subsequently producing uric acid. The enzyme complex exists in separate but interconvertible forms, xanthine dehydrogenase (XDH) and xanthine oxidase (XOD). XOD is one of the major cellular sources of superoxide production and is well known as a causative factor in ischemia/reperfusion damage. At present, almost no information on the conversion status is available with respect to aging. In the present study, we investigated the effect of age on the XOD/XDH status and gene expression in the kidney. In addition, we assessed XOD-induced reactive oxygen species (ROS) using the dichlorofluoroscein (DCF) method. Our results show that XD activity gradually up to 18 months of age and then a slight decrease at 24 months of age. XDH activity showed increases up to 18 months of age, then decreased at 24 months of age. The conversion of XDH to XOD, assessed by changes in the ratios of XOD/(XOD+XDH), showed an age-related increase, which peaked at 24 months. Levels of XD protein and its mRNA paralleled to overall XD activity. ROS generation has tendency to increase with age. Our results suggest that the increased conversion of XDH to XOD observed with age may be an important contributing factor to the increased renal oxidative stress during aging.