Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

The Telmisartan Renoprotective Study from Incipient Nephropathy to Overt Nephropathy – Rationale, Study Design, Treatment Plan and Baseline Characteristics of the Incipient to Overt: Angiotensin II Receptor Blocker, Telmisartan, Investigation on Type 2 Diabetic Nephropathy (INNOVATION) Study

We planned the INNOVATION study to determine whether telmisartan, an angiotensin-2-receptor blocker, delays the progression of renal disease from incipient nephropathy to overt nephropathy in hypertensive or normotensive Japanese patients with type 2 diabetes mellitus. The INNOVATION study is a randomized, double-blind, placebo-controlled trial. Eligible patients must have incipient nephropathy (defined as a urinary albumin to creatinine ratio of 100-300 mg/g creatinine) and a serum creatinine concentration of < 1.5 mg/dl for men and < 1.3 mg/dl for women. Patients who need treatment with angiotensin II receptor blockers or angiotensin-converting enzyme inhibitors are excluded. Eligible patients are randomly assigned to three groups: telmisartan titrated to 40 mg; telmisartan titrated to 80 mg; or placebo. The primary endpoint is the time from baseline visit to first detection of overt nephropathy (defined by a urinary albumin to creatinine ratio that is > 300 mg/g creatinine and 30% higher than the baseline on at least two consecutive visits). A total of 1855 patients have been enrolled from 160 study centres. In 527 randomized patients (28.4% of the enrolled patients), mean (SD) urinary albumin to creatinine ratio and serum creatinine concentration at baseline were 173.3 (47.2) mg/g creatinine and 0.78 (0.19) mg/dl. Sixty-eight per cent of the patients had hypertension at baseline. Mean (SD) systolic and diastolic blood pressures at baseline were 137.1 (14.6) and 77.5 (10.3) mmHg. The INNOVATION study will determine whether telmisartan, an angiotensin II receptor blocker, provides clinical benefits in hypertensive or normotensive patients with diabetes mellitus and diabetic nephropathy.

Prevalence of resistant hypertension and associated factors in Japanese subjects with type 2 diabetes

OBJECTIVE

The prevalence of treatment resistant hypertension (RH) depends on methods used for blood pressure (BP) measurements, goals of BP, and therapeutic efforts in terms of medication and adherence. We focused on diabetic subjects and explored the prevalence of RH in primary care practice.

METHODS

In 1737 subjects with type 2 diabetes who continued regular visits, office BP was evaluated by multiple measurements over one year. RH was defined as using more than four antihypertensive drugs or failure to achieve the goal with three antihypertensive drugs from different classes. The RH prevalence was investigated with BP goals <130/80 and 140/90 mmHg.

RESULTS

The percentage of subjects who achieved BP goals <130/80 and 140/90 were 70.5% and 93.8% with adherence to medication ≥95%, and the corresponding prevalence rates of RH in treated subjects were 28.4% and 21.8%, respectively. Factors independently associated with RH were age (odds ratio 1.02 [95% CI 1.01-1.04]), body mass index (1.10 [1.06-1.13]), variability in systolic BP (1.06 [1.02-1.09]), triglycerides (2.86 [1.34-6.11]), macroalbuminuria (3.33 [2.03-5.48]), estimated glomerular filtration rate (0.98 [0.97-0.99]), retinopathy (1.91 [1.39-2.61]), and family history of hypertension (1.85 [1.23-2.21]). Worsening albuminuria and glomerular filtration rate enhanced the prevalence of RH in a graded manner.

CONCLUSION

Careful estimation of office BP values over one year with a high achievement of BP goals and adequate adherence revealed that the prevalence of RH in type 2 diabetes is high. RH was characterized by accumulation of cardiovascular genetic and environmental risks.

Chronic kidney disease categories and renal-cardiovascular outcomes in type 2 diabetes without prevalent cardiovascular disease: a prospective cohort study (JDDM25)

AIMS/HYPOTHESIS

In type 2 diabetic patients at low risk for cardiovascular disease (CVD), the relationship between the clinical course of nephropathy by stage of chronic kidney disease (CKD) and onset of CVD remains unclear. Clarification of this relationship is important for clinical decision-making for both low- and high-risk diabetic patients.

METHODS

This 4 year prospective study enrolled 2,954 type 2 diabetic patients with no prevalent CVD, and serum creatinine <176.8 μmol/l. The risk for CVD onset (non-fatal and fatal CVD and stroke, and peripheral arterial disease) was assessed according to CKD stage categorised by urinary albumin-to-creatinine ratio (ACR; mg/mmol) and estimated GFR (eGFR; ml min(-1) 1.73 m(-2)). Association of progression from 'no CKD' stage (ACR <3.5 mg/mmol and eGFR ≥ 90 ml min(-1) 1.73 m(-2)) with risk for CVD onset was also evaluated.

RESULTS

During follow-up (median 3.8 years), 89 CVD events occurred. Compared with patients with 'no CKD' as reference, those with ACR ≥ 35.0 mg/mmol with co-existing eGFR 60-89 ml min(-1) 1.73 m(-2) or <60 ml min(-1) 1.73 m(-2) showed increased risk for CVD onset, whereas those with eGFR ≥ 90 ml min(-1) 1.73 m(-2) did not. Those with ACR <3.5 mg/mmol and eGFR <60 ml min(-1) 1.73 m(-2) did not show any increased risk. Among patients with 'no CKD' stage at baseline, those who progressed to ACR ≥ 3.5 mg/mmol during follow-up showed an increased risk compared with those who did not, whereas those who progressed to eGFR <90 ml min(-1) 1.73 m(-2) did not have increased risk.

CONCLUSIONS/INTERPRETATION

The risk for CVD was associated with progression of albuminuria stage rather than eGFR stage in type 2 diabetic patients at relatively low risk for CVD.

Reduction of both beta cell death and alpha cell proliferation by dipeptidyl peptidase-4 inhibition in a streptozotocin-induced model of diabetes in mice

AIMS/HYPOTHESIS

Incretins stimulate insulin secretion in a glucose-dependent manner but also promote pancreatic beta cell protection. Dipeptidyl peptidase-4 (DPP-4) inhibitors are a new glucose-lowering treatment that blocks incretin degradation by DPP-4. We assessed whether DPP-4 inhibition suppresses the progression to hyperglycaemia in a low-dose streptozotocin (STZ)-induced diabetic mouse model, and then investigated how DPP-4 inhibition affects islet function and morphology.

METHODS

The DPP-4 inhibitor, des-fluoro-sitagliptin (SITA), was administered to mice during and after STZ injections, and in some mice also before STZ.

RESULTS

In control mice, STZ resulted in hyperglycaemia associated with impaired insulin secretion and excess glucagon secretion. In SITA-treated STZ mice, these metabolic abnormalities were improved, particularly when SITA administration was initiated before STZ injections. We observed beta cell loss and dramatic alpha cell expansion associated with decreased insulin content and increased glucagon content after STZ administration. In SITA-treated mice, islet architecture and insulin content were preserved, and no significant increase in glucagon content was observed. After STZ exposure, beta cell apoptosis increased before hyperglycaemia, and SITA treatment reduced the number of apoptotic beta cells. Interestingly, alpha cell proliferation was observed in non-treated mice after STZ injection, but the proliferation was not observed in SITA-treated mice.

CONCLUSIONS/INTERPRETATION

Our results suggest that the ability of DPP-4 inhibition to suppress the progression to STZ-induced hyperglycaemia involves both alleviation of beta cell death and alpha cell proliferation.

Effects of olmesartan on renal and cardiovascular outcomes in type 2 diabetes with overt nephropathy: a multicentre, randomised, placebo-controlled study

AIMS/HYPOTHESIS

The renal and cardiovascular protective effects of angiotensin receptor blocker (ARB) remain controversial in type 2 diabetic patients treated with a contemporary regimen including an angiotensin converting enzyme inhibitor (ACEI).

METHODS

We examined the effects of olmesartan, an ARB, on primary composite outcome of doubling of serum creatinine, endstage renal disease and death in type 2 diabetic patients with overt nephropathy. Secondary outcome included composite cardiovascular outcomes, changes in renal function and proteinuria. Randomisation and allocation to trial group were carried out by a central computer system. Participants, caregivers, the people carrying out examinations and people assessing the outcomes were blinded to group assignment.

RESULTS

Five hundred and seventy-seven (377 Japanese, 200 Chinese) patients treated with antihypertensive therapy (73.5% [n = 424] received concomitant ACEI), were given either once-daily olmesartan (10-40 mg) (n = 288) or placebo (n = 289) over 3.2 ± 0.6 years (mean±SD). In the olmesartan group, 116 developed the primary outcome (41.1%) compared with 129 (45.4%) in the placebo group (HR 0.97, 95% CI 0.75, 1.24; p = 0.791). Olmesartan significantly decreased blood pressure, proteinuria and rate of change of reciprocal serum creatinine. Cardiovascular death was higher in the olmesartan group than the placebo group (ten vs three cases), whereas major adverse cardiovascular events (cardiovascular death plus non-fatal stroke and myocardial infarction) and all-cause death were similar between the two groups (major adverse cardiovascular events 18 vs 21 cases, all-cause deaths; 19 vs 20 cases). Hyperkalaemia was more frequent in the olmesartan group than the placebo group (9.2% vs 5.3%).

CONCLUSIONS/INTERPRETATION

Olmesartan was well tolerated but did not improve renal outcome on top of ACEI.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00141453.

Long-term effect of modification of dietary protein intake on the progression of diabetic nephropathy: a randomised controlled trial

AIMS/HYPOTHESIS

There is currently insufficient evidence to recommend a low-protein diet for type 2 diabetic patients with diabetic nephropathy. We assessed whether a low-protein diet could prevent the progression of diabetic nephropathy.

METHODS

This was a multi-site parallel randomised controlled trial for prevention of diabetic nephropathy progression among 112 Japanese type 2 diabetic patients with overt nephropathy. It was conducted in Japan from 1 December 1997 to 30 April 2006. The participants were randomly assigned using a central computer-generated schedule to either low-protein diet (0.8 g kg(-1) day(-1)) and normal-protein diet (1.2 g kg(-1) day(-1)), and were followed for 5 years. The participants and investigators were not blinded to the assignment. The primary outcomes were the annual change in estimated GFR and creatinine clearance, the incidence of doubling of serum creatinine and the time to doubling of baseline serum creatinine.

RESULTS

The study was completed by 47 (84%) of 56 participants in the low-protein diet group and 41 (73%) of 56 participants in the normal-diet group. During the study period, the difference in mean annual change in estimated GFR between the low-protein diet and the normal-protein diet groups was -0.3 ml min(-1) 1.73 m(-2) (95% CI -3.9, 4.4; p = 0.93). The difference in mean annual change in creatinine clearance between the low-protein diet and the normal-protein diet groups was -0.006 ml s(-1) 1.73 m(-2) (95% CI -0.089, 0.112; p = 0.80). A doubling of serum creatinine was reached in 16 patients of the low-protein group (34.0%), compared with 15 in the normal-protein group (36.6%), the difference between groups being -2.6% (95% CI -22.6, 17.5; p = 0.80). The time to doubling of serum creatinine was similar in both groups (p = 0.66).

CONCLUSIONS/INTERPRETATION

It is extremely difficult to get patients to follow a long-term low-protein diet. Although in the low-protein group overall protein intake was slightly (but not significantly) lower, it did not confer renoprotection.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT00448526.

FUNDING

Research grant from the Ministry of Health, Labour and Welfare of Japan.

Prooxidant action of furanone compounds: Implication of reactive oxygen species in the metal-dependent strand breaks and the formation of 8-hydroxy-2′-deoxyguanosine in DNA

Prooxidant properties of furanone compounds including 2,5-furanone (furaneol, 4-hydroxy-2,5-dimethyl-furan-3-one), 4,5-furanone (4,5-dimethyl-3-hydroxy-2(5H)-furanone) (sotolone) and cyclotene (2-hydroxy-3-methyl-2-cyclopenten-1-one) were analyzed in relation to the metal-reducing activity. Only 2.5-furanone known as a "strawberry or pineapple furanone" inactivated aconitase the most sensitive enzyme to active oxygen in the presence of ferrous sulfate, suggesting the furaneol/iron-mediated generation of reactive oxygen species. 2,5-Furanone caused strand scission of pBR322 DNA in the presence of copper. Treatment of calf thymus DNA with 2,5-furanone plus copper produced 8-hydroxy-2'-deoxyguanosine in DNA. 2,5-Furanone showed a potent copper-reducing activity, and thus, DNA strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine by 2,5-furanone can be initiated by the production of superoxide radical through the reduction of cupric ion to cuprous ion, resulting in the conversion to hydrogen peroxide and hydroxyl radical. However, an isomer and analog of 2,5-furanone, 4,5-furanone and cyclotene, respectively, did not show an inactivation of aconitase, DNA injuries including strand breakage and the formation of 8-hydroxy-2'-deoxyguanosine, and copper-reducing activity. Cytotoxic effect of 2,5-furanone with hydroxyketone structure can be explained by its prooxidant properties: furaneol/transition metal complex generates reactive oxygen species causing the inactivation of aconitase and the formation of DNA base damage by hydroxyl radical.

Predictive impact of elevated serum level of IL-18 for early renal dysfunction in type 2 diabetes: an observational follow-up study

AIMS/HYPOTHESIS

The early identification of type 2 diabetic patients at risk of developing microalbuminuria-an independent risk factor for renal and cardiovascular diseases-is important to improve the patients' outcomes. We investigated whether serum levels of IL-18, a proinflammatory cytokine, were a predictor of early renal dysfunction.

MATERIALS AND METHODS

A total of 249 Japanese type 2 diabetic patients without overt proteinuria were enrolled in an observational follow-up study (median follow-up 7 years), and their stage of diabetic nephropathy was classified and their estimated glomerular filtration rate (eGFR) was calculated annually.

RESULTS

At baseline, serum levels of IL-18 were higher in subjects with microalbuminuria (n = 76) than in those with normoalbuminuria (n = 173). Elevated serum levels of IL-18 were associated with the progression of nephropathy to a higher stage in normoalbuminuric subjects (118 [interquartile range 91-159] ng/l vs 155 [interquartile range 121-205] ng/l, p = 0.003), but not in microalbuminuric subjects (154 [interquartile range 113-200] ng/l vs 160 [interquartile range 101-190] ng/l, p = 0.50). The adjusted risk for developing microalbuminuria was 3.6 (95% CI 1.2-10.4) in normoalbuminuric subjects with serum IL-18 levels above the median (>/=134.6 ng/l), and was significantly enhanced in those urinary AERs at the upper end of the normal range (7.5 mug/min </= AER < 20 microg/min). Furthermore, the annual rate of decline in eGFR, when examined in the study population as a whole, was significantly greater in subjects with serum IL-18 levels above the median than in other subjects.

CONCLUSIONS/INTERPRETATION

The results of our observational follow-up study indicate that elevated serum levels of IL-18 may be a predictor of future renal dysfunction in type 2 diabetic patients with normoalbuminuria.

Glucocorticoid-induced diabetes mellitus: prevalence and risk factors in primary renal diseases

BACKGROUND/AIMS

In patients with primary renal diseases the current knowledge of hyperglycemia associated with corticosteroid therapy is limited. We therefore examined the prevalence and risk factors of glucocorticoid-induced diabetes mellitus (DM) in primary renal diseases.

METHODS

Patients were recruited with primary renal diseases who were started on corticosteroids between April 2002 and June 2005. In patients with DM, an impaired fasting glucose level and/or positive urinary glucose analyses before corticosteroids therapy were excluded.

RESULTS

During corticosteroid therapy (initial dose: prednisolone 0.75 +/- 0.10 mg/kg/day), DM was newly diagnosed in 17 (40.5%) of 42 patients. All of the 17 patients were diagnosed as having DM by postprandial hyperglycemia at 2 h after lunch, although they had normal fasting blood glucose levels. Age (OR 1.40, 95% CI 1.06-1.84) and body mass index (OR 1.87, 95% CI 1.03-3.38) were determined as independent risk factors for glucocorticoid-induced DM.

CONCLUSION

Over 40% of patients with primary renal disease developed DM during treatment with corticosteroids. A high age and high body mass index are the independent risk factors for glucocorticoid-induced DM. 24-hour urinary glucose analyses and postprandial plasma glucose are useful for detecting glucocorticoid-induced DM.

Protective effect of NADP-isocitrate dehydrogenase on the paraquat-mediated oxidative inactivation of aconitase in heart mitochondria

Protective role of NADP-isocitrate dehydrogenase in the oxidative inactivation of mitochondrial enzymes was analyzed. Administration of paraquat to the rat inactivated liver mitochondrial enzymes: the aconitase activity decreased to one quarter, and citrate synthase and fumarase to half, whereas cytosolic enzymes were not affected. Activities of heart mitochondrial and cytosolic enzymes were not at all changed in the rat treated with paraquat, but paraquat directly inactivated aconitase in the heart mitochondria isolated from the non-treated rats. The paraquat-dependent inactivation of aconitase was prevented by activating NADP-isocitrate dehydrogenase in the presence of oxidized glutathione. NADP-isocitrate dehydrogenase could regenerate glutathione in isolated heart mitochondria, indicating that paraquat-mediated inactivation depends on the glutathione-regenerating activity by enhanced NADPH supply. Lower NADP-isocitrate dehydrogenase activity in liver mitochondria cannot regenerate reduced glutathione for scavenging reactive oxygen species, resulting in the paraquat-induced oxidative inactivation of mitochondrial enzymes. However, higher activity of NADP-isocitrate dehydrogenase participates in the regeneration of reduced glutathione causing stabilization of enzymes in heart mitochondria.

Intestinal thrombotic microangiopathy after allogeneic bone marrow transplantation: a clinical imitator of acute enteric graft-versus-host disease

Thrombotic microangiopathy after bone marrow transplantation (post-BMT TMA) is a serious transplant-related complication. We identified 16 patients with TMA after allogeneic BMT who showed histopathological evidence of intestinal TMA in their gut specimens (six autopsies, 10 biopsies). In all, 14 patients had grade II-IV acute graft-versus-host disease (GVHD). The first seven patients were retrospectively diagnosed with TMA. Since six of them were diagnosed with progressive GVHD at that time because there was no awareness of the existence of intestinal TMA, they received more intensive treatment for GVHD, but all died between days +49 and +253. In contrast, the remaining nine patients were recently diagnosed with intestinal TMA on the basis of colonoscopic biopsies. For eight of these patients, the immunosuppressants were reduced, and the patients' intestinal symptoms improved gradually. Six of the nine patients were still alive 12 months after the diagnosis of TMA. Our findings suggest that the gut may be a site involved in post-BMT TMA, presenting as ischemic enterocolitis. Differentiating intestinal TMA from acute GVHD is important in patients suffering from severe and refractory diarrhea after BMT.

Prooxidant action of gallic acid compounds: copper-dependent strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine in DNA

Gallic acid and its alkylesters, polyphenolic compounds with antioxidative activity, acted as a prooxidant causing a copper-dependent DNA damage. Treatment of DNA from plasmid pBR322 and calf thymus with gallic acid plus copper ion caused strand scission and the formation of 8-hydroxy-2'-deoxyguanosine in DNA. Addition of catalase protected DNA from the gallic acid/copper-dependent strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine, indicating that hydroxyl radical may participate in the DNA damage. Ethyl-, propyl- and butylgallates showed only a little DNA damage. Octyl- and laurylgallates caused negligible damage of DNA. DNA strand breaks and formation of 8-hydroxy-2'-deoxyguanosine were closely related to the reduction of copper by gallate compounds. These results imply that cuprous ion reduced by gallate derivatives may play a key role in the oxidative cleavage of DNA and the formation of base adduct. The cytotoxic effect of gallate compounds can be explained by their prooxidant action dependent on the reducing activity.

Identification of a novel GH isoform: a possible link between GH and melanocortin systems in the developing chicken eye

GH is considered to play a role in the pathogenesis of diabetic retinopathy, causing neovascularization in the retina. The present study was conducted to assess the possibility that GH may play a role in ocular development by determining whether GH is expressed in the eye of the chicken during development. In the 17-d-old embryo, immunocytochemistry detected immunoreactive GH in retinal pigment epithelial (RPE) cells. Characterization of GH mRNA expressed in the eye by RT-PCR and rapid amplification of cDNA 5'-ends revealed it to be a novel GH mRNA transcribed from the middle of the intron 3 of the chicken GH (cGH) gene. The deduced protein, designated small GH isoform (s-cGH), was a cytosolic protein of 16.5 kDa with 140 amino acid (aa) residues, lacking the signal peptide and the N-terminal 71 aa residues of 22-kDa cGH, replacing them with 20 aberrant aa residues, and identical to 22-kDa cGH for the C-terminal 120-aa residue portion. Western blotting determined the molecular size of immunoreactive GH in RPE cells to be 80-84 kDa, similar to the computed molecular mass of s-cGH/GH receptor complex. Furthermore, RT-PCR demonstrated that GH receptor mRNA, but not s-cGH mRNA, was expressed in RPE cells. These results suggest that RPE cell is one of the target cells of s-cGH in the eye. During embryonic development, the immunoreactivity for s-cGH in RPE cells was initially observed on embryonic d 10, and the staining intensity increased and peaked on embryonic d 17. By hatching, s-cGH immunoreactivity in RPE cells was gradually decreased, and it was not detectable after hatching. This ontogenetic staining pattern correlates well with the pattern of the production of alpha MSH in RPE cells. The cell type expressing s-cGH remains to be identified; however, our findings imply a possible involvement of GH in the regulation of ocular development by acting on the intraocular melanocortin system in the chicken.

Increased arterial wall stiffness limits flow volume in the lower extremities in type 2 diabetic patients

OBJECTIVE

To document an association between arterial wall stiffness and reduced flow volume in the lower-extremity arteries of diabetic patients.

RESEARCH DESIGN AND METHODS

We recruited 60 consecutive type 2 diabetic patients who had no history or symptoms of peripheral arterial disease (PAD) in the lower extremities and normal ankle/brachial systolic blood pressure index at the time of the study (non-PAD group) and 20 age-matched nondiabetic subjects (control group). We used an automatic device to measure pulse wave velocity (PWV) in the lower extremities as an index of arterial wall stiffness. At the popliteal artery, we evaluated flow volume and the resistive index as an index of arterial resistance to blood flow using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging.

RESULTS

Consistent with previous reports, we confirmed that the non-PAD group had an abnormally higher PWV compared with that of the control group (P < 0.001). To further demonstrate decreased flow volume and abnormal flow pattern at the popliteal artery in patients with a higher degree of arterial wall stiffness, we assigned the 60 non-PAD patients to tertiles based on their levels of PWV. In the highest group, magnetic resonance angiograms of the calf and foot arteries showed decreased intravascular signal intensity, indicating the decreased arterial inflow in those arteries. The highest group was also characterized by the lowest late diastolic and total flow volumes as well as the highest resistive index among the groups. From stepwise multiple regression analysis, PWV and autonomic function were identified as independent determinants for late diastolic flow volume (r(2) = 0.300; P < 0.001).

CONCLUSIONS

Arterial wall stiffness was associated with reduced arterial flow volume in the lower extremities of diabetic patients.

Association of the DD genotype and development of Japanese type 2 diabetic nephropathy

We determined the insertion/deletion (I/D) polymorphism of the angiotensin-coverting enzyme (ACE) gene in a multicenter trial of ethnically homogeneous Japanese type 2 diabetes mellitus (DM) patients. All patients (n = 748) were divided into 5 groups as follows: group I (normoalbuminuric patients), group II (microalbuminuric patients), group III (overt albuminuric patients with serum creatinine (s-Cr) levels of less than 1.2 mg/dl), group IV (overt albuminuric patients with s-Cr levels of more than 1.3 mg/dl but excluding hemodialysis patients), and group V (hemodialysis patients). We selected patients with a diabetic duration of more than 15 years in the mild stage (groups I and II), but placed no limits on those in the advanced and end-stages (groups III, IV and V). The frequency of the DD genotype was slightly higher in the advanced and end stages. The frequency of the DD genotype in the mild stage differed from that in the end stage (II/ID/DD 47.8%/41.0%/11.2% vs. 37.0 %/43.3%/19.7% p = 0.07, II + ID/DD 88.8%/11.2% vs. 80.3%/19.7%, p < 0.05). D allele frequency in the mild stage also differed from that in the end stage (I/D 68.3%/31.7% vs. 58.7%/41.3%, p < 0.02). The presence of the DD genotype increased the risk of end-stage renal disease (ESRD) more than that of the other genotypes (odds ratio ID/II = 1.37, 95% CI 0.82-2.27; DD/II = 2.27, 95% CI 1.12-4.61). It appears that the DD genotype is associated with progression of Japanese type 2 diabetic nephropathy.

Dinucleotide repeat polymorphism of matrix metalloproteinase-9 gene is associated with diabetic nephropathy

BACKGROUND

Although genetic susceptibility has been proposed as an important factor for the development and progression of diabetic nephropathy, the definitive gene has not been identified. To identify the genetic marker for diabetic nephropathy, we examined the association between the (A-C)n dinucleotide repeat polymorphism upstream of the matrix metalloproteinase-9 (MMP-9) gene and diabetic nephropathy in a group of Japanese patients with type 2 diabetes.

METHODS

Patients were divided into three groups based on their urinary albumin excretion rate (AER) and the stage of diabetic retinopathy as follows: uncomplicated group (U), normal albuminuria (AER <20 microg/min) without proliferative retinopathy and with the duration of diabetes more than 20 years (N = 32); microalbuminuria group (M), 20 < or = AER < 200 microg/min (N = 155); overt nephropathy group (O), AER > or = 200 microg/min (N = 63). The region containing the dinucleotide repeat upstream of MMP-9 gene was amplified by polymerase chain reaction (PCR). The amplified products were analyzed with 7% formamide/urea acrylamide gel electrophoresis. The promoter constructs of the MMP-9 gene were transfected with the CMV-beta-galactosidase construct into 293 cells using the liposome method. Twenty-four hours after transfection, cells were harvested, and luciferase and beta-galactosidase activities were measured.

RESULTS

Nine alleles of the dinucleotide repeat polymorphism (17 to 25 repeats) were identified, and the frequency of each allele in diabetic subjects was not different from that in nondiabetic controls. The frequency of the allele containing 21 repeats (A21) was most abundant (42.4% in control and 45.6% in diabetic subjects), followed by the allele with 23 repeats (A23; 35.4% in control and 27.6% in diabetic subjects). The A21 allele was less frequent in M and O than U (O, 38.9%; M, 45.5%; U, 59.3%, chi2 = 7.18; P < 0.05, O vs. U), while the frequency of the alleles other than A21 was not different among each group. The calculated odds ratio for nephropathy in the noncarrier, heterozygote, or homozygote of A21 allele was 3.38, 1.97, and 0.2, respectively. Furthermore, the promoter assay for the MMP-9 gene revealed that the A21 allele had a higher promoter activity compared with other alleles. No significant correlation was observed between serum MMP-9 concentrations and the MMP-9 gene polymorphism.

CONCLUSION

These results indicate that the patients with A21 allele of the MMP-9 gene may be protected from the development and progression of diabetic nephropathy. Thus, the microsatellite polymorphism upstream of the MMP-9 gene could be a useful genetic marker for diabetic nephropathy.

Cellular mechanisms in the development and progression of diabetic nephropathy: activation of the DAG-PKC-ERK pathway

Diabetic nephropathy is characterized functionally by glomerular hyperfiltration and albuminuria and histologically by the expansion of glomerular mesangium. We and others have found that protein kinase C (PKC) is activated through an increase in de novo synthesis of diacylglycerol (DAG) from glucose in glomerular mesangial cells cultured under high glucose conditions and in glomeruli of diabetic rats. The activation of PKC could activate further various intracellular signal transduction systems, such as extracellular regulated kinase (ERK). The activation of the DAG-PKC-ERK pathway is considered to be one of the important molecular mechanisms of the development and progression of diabetic nephropathy. To prove this hypothesis, we examined whether the inhibition of the DAG-PKC-ERK pathway could prevent the development of glomerular dysfunction in diabetic animals. First, we found that thiazolidinedione compounds could inhibit PKC activation by activating DAG kinase. Thiazolidinedione compounds were able to prevent glomerular hyperfiltration, albuminuria, and excessive production of extracellular matrix proteins in glomeruli in streptozotocin-induced diabetic rats, a model for type 1 diabetes. Second, we tried to inhibit PKC directly by oral administration of PKC beta inhibitor. PKC beta inhibitor could prevent albuminuria and mesangial expansion in db/db mice, a model for type 2 diabetes. These results confirmed the importance of the activation of the DAG-PKC-ERK pathway in the development of glomerular dysfunction in diabetes.

Expression of Rho-family GTPases (Rac, cdc42, RhoA) and their association with p-21 activated kinase in adult rat peripheral nerve

To clarify the presence of the Rho family of small GTPases p21-activated kinase (pak) signaling pathway in the PNS, we have examined their expression, the association between the small GTPases and pak and the pak kinase activity in the PNS using immunoblot analysis, immunohistochemistry, co-immunoprecipitation study, and in vitro kinase assay. Immunoblot analysis showed the expression of Rac, cdc42, RhoA and pak in the dorsal root ganglion (DRG) and sciatic nerve. The localization of these proteins in the DRG neurons and axons and Schwann cells of the sciatic nerve was confirmed by immunohistochemistry. Co-immunoprecipitation studies indicated the in vivo associations of pak with Rac and cdc42, but not with RhoA, in both the DRG and sciatic nerve. The autophosphorylation of pak and phosphorylation of histone H4 by pak were also found in the DRG and sciatic nerve as well as in the CNS. These results suggest that the Rac/cdc42-pak signaling pathway exists and functions in the PNS and may mediate some intracellular signals.

Aluminum-induced apoptosis in PC12D cells

The addition of aluminum-maltol complex to PC12D cells induced a time-dependent and concentration-dependent growth inhibition as well as cell death, whereas aluminum chloride or maltol alone did not affect the viability of PC12D cells. Apoptosis of differentiated PC12D cells was assessed by using terminal deoxynucleotidyltransferase-mediated 2'-deoxyuridine-5'-triphosphate nick end labeling (TUNEL) technique to detect DNA strand breaks in situ. The number of TUNEL-positive cells treated with aluminum-maltol increased with time in the treatment cultures. The ability of aluminum ion to elevate intracellular reactive oxygen species was determined by fluorescence in PC12D cells loaded with the oxidant-sensitive dye 2',7'-dichlorofluorescin diacetate. Aluminum ion incorporated to PC 12D cells causes apoptotic cell death by enhancing the generation of reactive oxygen species.

Enhancement of glomerular heme oxygenase-1 expression in diabetic rats

An increase in oxidative stress in diabetic subjects is implicated to play a pivotal role in diabetic vascular complications. In response to oxidative stress, antioxidant enzymes are considered to be induced and protect cellular functions to keep in vivo homeostasis. However, it remains to be clarified whether antioxidant enzymes are induced against oxidative stress especially in renal glomeruli at an early stage of diabetes. To answer this question, we examined the gene expression of a variety of antioxidant enzymes in glomeruli isolated from streptozotocin-induced diabetic rats. The mRNA expression of antioxidant enzymes such as catalase, glutathione peroxidase, and CuZn-superoxide dismutase, was unaltered in glomeruli of diabetic rats and was comparable to control rats. In contrast, the mRNA expression of heme oxygenase-1 (HO-1) was enhanced in glomeruli of diabetic rats as compared with control rats. A treatment with insulin as well as with vitamin E (40 mg/kg body weight every other day, intra-peritoneal injection) normalized the mRNA expression of HO-1 in the glomeruli of diabetic rats. Immunohistochemical analysis revealed that the up-regulated expression of HO-1 protein was localized in glomerular cells of diabetic rats. In conclusion, these results provide the first evidence that among antioxidant enzymes HO-1 expression is preferentially increased in diabetic glomeruli.

Purification, molecular cloning, and immunohistochemical localization of dipeptidyl peptidase II from the rat kidney and its identity with quiescent cell proline dipeptidase

We purified dipeptidyl peptidase II (DPP II) to homogeneity from rat kidney and determined its physicochemical properties, including its molecular weight, substrate specificity, and partial amino acid sequence. Furthermore, we screened a rat kidney cDNA library, isolated the DPP II cDNA and determined its structure. The cDNA was composed of 1,720 base pairs of nucleotides, and 500 amino acid residues were predicted from the coding region of cDNA. Human quiescent cell proline dipeptidase (QPP) cloned from T-cells is a 58-kDa glycoprotein existing as a homodimer formed with a leucine zipper motif. The levels of amino acid homology were 92.8% (rat DPP II vs. mouse QPP) and 78.9% (rat DPP II vs. human QPP), while those of nucleotide homology were 93.5% (rat DPP II vs. mouse QPP) and 79.4% (rat DPP II vs. human QPP). The predicted amino acid sequences of rat DPP II and human and mouse QPP possess eight cysteine residues and a leucine zipper motif at the same positions. The purified DPP II showed similar substrate specificity and optimal pH to those of QPP. Consequently, it was thought that DPP II is identical to QPP. Northern blot analysis with rat DPP II cDNA revealed prominent expression of DPP II mRNA in the kidney, and the order for expression was kidney >> testis > or = heart > brain > or = lung > spleen > skeletal muscle > or = liver. In parallel with Northern blot analysis, the DPP II antigen was detected by immunohistochemical staining in the cytosol of epithelial cells in the kidney, testis, uterus, and cerebrum.

Evaluation of a new care system provided to diabetic patients in the outpatient clinic

OBJECTIVE

Evaluation of metabolic states and chronic complications is essential for maintaining a high quality of care for diabetic patients. We have assessed the quality of care in routine outpatient clinics for diabetic subjects in our university hospital, and compared with those in a newly introduced standardized clinic to evaluate the new care system.

METHODS

The quality of care was assessed by the chart review in 1995, and compared with those from 1996-1997 in the "Diabetes Follow-up Clinic" which is systematically designed for the standardized care.

PATIENTS

The subjects were recruited among 860 patients who visited the outpatient clinic in July and August of 1995 with a diagnosis of diabetes or glucose intolerance. Six hundred seventy-two patients whose follow-up period had been more than 6 months with clinically diagnosed diabetes were used for the analysis.

RESULTS

Laboratory tests such as determination of HbA1c, and serum levels of lipids and creatinine were performed in more than 90% of the patients in the routine outpatient clinics. However, ophthalmology referral, 24-hour urine collection for the determination of creatinine clearance and albumin excretion, and electrocardiograms were not well performed and were incompletely documented (40-60% of the patients within a previous year and 70-80% in the last 2 years). In the standardized "Diabetes Follow-up Clinic", only four out of 555 diabetic patients failed to collect their 24-hour urine, and all participants had ankle blood pressure measurements, nerve conduction study, and nylon monofilament tests, etc. Furthermore, more than 95% of the patients had funduscopic examinations by ophthalmologists as well as records of electrocardiogram.

CONCLUSION

Introduction of the standardized "Diabetes Follow-up Clinic" may be one of the choices for increasing the quality of outpatient care and for the prevention of chronic diabetic complications.

Role of mitogen-activated protein kinases as downstream effectors of transforming growth factor-beta in mesangial cells

Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine that regulates cell proliferation, differentiation, and production of extracellular matrix proteins in various types of cells including mesangial cells. Although TGF-beta has been also known as an important player in the pathogenesis of various fibrotic diseases including glomerulosclerosis, signal-transduction cascades of TGF-beta have remained to be clarified. However, emerging evidence indicates that TGF-beta can activate various signal transduction cascades such as Smad proteins and mitogen-activated protein kinases (MAPKs) in many types of cells. Here, we examine the role of MAPKs in TGF-beta-induced gene expression of extracellular matrix proteins in mesangial cells. TGF-beta increases extracellular signal-regulated kinase (ERK) activity, one of the MAPKs, and the expression of fibronectin mRNA and protein in rat mesangial cells. Furthermore, PD98059, a specific inhibitor of MAPK/ERK kinase (MEK), can inhibit this TGF-beta-induced fibronectin expression. These data suggest that MAPKs play an important role in TGF-beta-mediated extracellular matrix production in mesangial cells.

Increases in K+ conductance and Ca2+ influx under high glucose with suppressed Na+/K+-pump activity in rat myelinated nerve fibers

To test the combined effect of high glucose and decreased Na+/K+-pump activity, a condition which closely mimics the diabetic state, on nerve ionic currents, changes in action potential and membrane current induced by high glucose in the presence of ouabain were investigated using voltage clamp analysis in rat single myelinated nerve fibers. In the presence of 0.1 mM ouabain, 30 mM glucose caused a progressive increase in the delayed K+ current as well as persistent decreases in action potential and Na+ current, suggesting that Na+/K+ pump plays an important role in preventing the increase in the K+ current. The latter increase was suppressed by a blocker of Ca2+-activated K+ channels. Two types of voltage-dependent Ca2+ channel blockers (L and N-type) as well as a Na+/Ca2+-exchange blocker diminished the ouabain-induced increase in K+ conductance. These results suggest that high glucose with suppressed Na+/K+ pump activity might induce an increase of Ca2+ influx through either Ca2+ channels or reverse Na+/Ca2+-exchange, possibly leading to the elevation of Ca2+-activated voltage-dependent K+ channels. Both a decrease in inward Na+ current and an increase in K+ conductance may result in decreased nerve conduction. In addition, a possible increase of axoplasmic Ca2+ concentration may lead to axonal degeneration. These results provide a clue for understanding the pathophysiologic mechanism of diabetic neuropathy.

Usefulness of waveform analysis of popliteal artery in type II diabetic patients using gated magnetic resonance 2D-cine-PC imaging and 31P spectroscopy

AIMS/HYPOTHESIS

We studied 76 patients with Type II (non-insulin-dependent) diabetes mellitus and 16 age-matched non-diabetic subjects (control group) to clarify qualitative and quantitative abnormalities of waveform and flow volume of the popliteal artery.

METHODS

The 76 diabetic patients comprised 16 patients with occlusive arterial disease in the lower extremities [arteriosclerosis obliterans (ASO) group] and 60 patients free from this disease (non-ASO group). We flow analysed the popliteal artery and measured the phosphocreatine to inorganic phosphate ratio of resting plantar muscles to identify risk factors for foot lesions using gated magnetic resonance two-dimensional cine-mode phase-contrast imaging and 31P spectroscopy.

RESULTS

The control and non-ASO groups had a triphasic waveform with systolic, early and late diastolic components. All ASO patients had an abnormal monophasic waveform and a lower ankle brachial index than that of the control and non-ASO groups. To clarify the mechanism of reduced flow volume of lower extremities, we assigned the 60 patients of the non-ASO group to the three subgroups based on their levels of total flow volume of the popliteal artery. The lowest group showed an abnormal triphasic waveform with lower amplitudes of systolic and late diastolic components and flow velocities in foot arteries than those of the highest group although ABI was similar. From stepwise multiple regression analysis, late diastolic flow volume was identified as an independent determinant for the phosphocreatine to inorganic phosphate ratio (r2 = 0.484, p < 0.001).

CONCLUSION/INTERPRETATION

Waveform analysis of popliteal artery provides a powerful tool for identifying impaired peripheral circulation caused by either occlusive arterial disease or increased arterial resistance in diabetic patients.

Thiazolidinedione compounds ameliorate glomerular dysfunction independent of their insulin-sensitizing action in diabetic rats

Thiazolidinedione (TZD) compounds are widely used as oral hypoglycemic agents. Herein, we provide evidence showing that troglitazone, one of the TZD compounds, is able to prevent glomerular dysfunction in diabetic rats through a novel mechanism independent of its insulin-sensitizing action. We examined the effect of troglitazone on functional and biochemical parameters of glomeruli in streptozotocin-induced diabetic rats. Troglitazone was able to prevent not only diabetic glomerular hyperfiltration and albuminuria, but an increase in mRNA expression of extracellular matrix proteins and transforming growth factor-beta1 in glomeruli of diabetic rats, without changing blood glucose levels. Biochemically, an increase in diacylglycerol (DAG) contents and the activation of the protein kinase C (PKC)-extracellular signal-regulated kinase (ERK) pathway in glomeruli of diabetic rats were abrogated by troglitazone. The activation of DAG-PKC-ERK pathways in vitro in mesangial cells cultured under high glucose conditions was also inhibited by troglitazone. Troglitazone enhanced the activities of DAG kinase, which could metabolize DAG to phosphatidic acid, in both glomeruli of diabetic rats and mesangial cells cultured under high glucose conditions. Surprisingly, pioglitazone, another TZD compound without alpha-tocopherol moiety in its structure, also prevented the activation of the DAG-PKC pathway and activated DAG kinase in mesangial cells cultured under high glucose conditions. These results may identify the TZDs as possible new therapeutic agents for diabetic nephropathy that prevent glomerular dysfunction through the inhibition of the DAG-PKC-ERK pathway.

Immunohistochemical characterization of glomerular PDGF B-chain and PDGF beta-receptor expression in diabetic rats

Platelet-derived growth factor (PDGF) was found to contribute to the pathophysiological process in the development and progression of glomerulosclerosis characterized by mesangial cell proliferation and accumulation of extracellular matrix. To examine the role of PDGF in the development of diabetic nephropathy, we conducted immunohistochemical analysis for PDGF B-chain (PDGF-B) and PDGF beta-receptor (PDGFR-beta) in the glomeruli of streptozotocin-induced diabetic rats. At 2, 4, and 12 weeks after the onset of diabetes, the expression of PDGF-B in glomeruli of diabetic rats was increased significantly as compared to control or diabetic rats treated with insulin. Similar changes were observed on PDGFR-beta immunostaining. The immunostaining of mirror sections revealed the existence of PDGF-B or PDGFR-beta not only in mesangial cells but also in visceral epithelial cells. Glomerular volume was significantly increased in diabetes. This early glomerular abnormality was prevented by an inhibition of PDGF system with trapidil as well as by the treatment of insulin. Our results suggest that the activation of the PDGF system in glomerular cells might play an important role in the development of early glomerular lesion in diabetes.

Significance of glomerular deposition of C3c and C3d in IgA nephropathy

BACKGROUND

Complement activation plays an important role in the pathogenesis of IgA nephropathy. The clinico-pathological significance of the glomerular deposition of complement breakdown products, C3c and C3d in IgA nephropathy remains to be clarified.

METHODS

We examined the relationship between glomerular staining patterns of C3c and C3d and clinico-pathological findings with 163 patients with IgA nephropathy. Renal biopsy specimens were stained with C3c and C3d by immunofluorescence, and patients were divided into the following two groups: the intensity of C3c deposition stronger than C3d deposition, or equal to it (group A); the intensity of C3d deposition stronger than C3c deposition (group B).

RESULTS

In group A, the incidence of severe hematuria (over 20 urinary red blood cells in high-power field microscope (x400)) or of higher urinary fibrinogen degenerated products (over 0.1 microg/ml) was significantly higher than that in group B. In addition, group A showed a significant decrease in the glomerular filtration rate. Group A also showed a significantly higher incidence of glomerular endocapillary proliferation than in group B.

CONCLUSION

These findings suggest that the glomerular deposition of C3c is associated with the inflammatory active phase of glomeruli in IgA nephropathy.

Amelioration of accelerated diabetic mesangial expansion by treatment with a PKC beta inhibitor in diabetic db/db mice, a rodent model for type 2 diabetes

Activation of protein kinase C (PKC) is implicated as an important mechanism by which diabetes causes vascular complications. We have recently shown that a PKC beta inhibitor ameliorates not only early diabetes-induced glomerular dysfunction such as glomerular hyperfiltration and albuminuria, but also overexpression of glomerular mRNA for transforming growth factor beta1 (TGF-beta1) and extracellular matrix (ECM) proteins in streptozotocin-induced diabetic rats, a model for type 1 diabetes. In this study, we examined the long-term effects of a PKC beta inhibitor on glomerular histology as well as on biochemical and functional abnormalities in glomeruli of db/db mice, a model for type 2 diabetes. Administration of a PKC beta inhibitor reduced urinary albumin excretion rates and inhibited glomerular PKC activation in diabetic db/db mice. Administration of a PKC beta inhibitor also prevented the mesangial expansion observed in diabetic db/db mice, possibly through attenuation of glomerular expression of TGF-beta and ECM proteins such as fibronectin and type IV collagen. These findings provide the first in vivo evidence that the long-term inhibition of PKC activation in the renal glomeruli can ameliorate glomerular pathologies in diabetic state, and thus suggest that a PKC beta inhibitor might be an useful therapeutic strategy for the treatment of diabetic nephropathy.

1H- and 31P-magnetic resonance spectroscopy and imaging as a new diagnostic tool to evaluate neuropathic foot ulcers in Type II diabetic patients

AIMS/HYPOTHESIS

We studied 36 Type II (non-insulin-dependent) diabetic patients without occlusive arterial diseases in the lower extremities and 12 age-matched and sex-matched non-diabetic subjects to clarify the association between diabetic polyneuropathy and foot ulcers using 1H- and 31P-magnetic resonance spectroscopy and imaging.

METHODS

The 36 diabetic patients consisted of 12 patients with superficial foot ulcers and 24 patients free from this disease. We measured fat to water and phosphocreatine to inorganic phosphate (PCr:Pi) ratios and calculated the intracellular pH of resting plantar muscles by depth-resolved surface-coil spectroscopy using an 1H-31P double tuned coil. Furthermore, foot vasculature, fat and PCr contents of plantar muscles were visualised by phase-contrast angiography, T1-weighted spin-echo imaging and 31P-chemical shift imaging.

RESULTS

The 12 foot ulcer patients showed a reduced PCr to Pi ratio (p < 0.001) and peripheral nerve functions (p < 0.01-0.001) but an increased fat to water ratio (p < 0.001) and intracellular pH (p < 0.001) compared with the 24 patients without ulcers. From stepwise multiple regression analyses, motor nerve function as well as severity of nephropathy was associated with both fat to water and PCr to Pi ratios. When these patients were categorised into three groups based on their level of motor nerve function, the frequency of foot ulcers of the lowest group was higher than that of the highest group.

CONCLUSION/INTERPRETATION

Our findings indicated that motor nerve dysfunction in diabetic patients was closely associated with impaired energy metabolism, fatty infiltration and increased intracellular pH of plantar muscles and high frequency of foot ulcers. These new techniques could contribute to help clarify the predisposing factors for foot ulcers.

[Kidney disease and insulin resistance--clinical impact of thiazolidinedione compounds for kidney disease]

The thiazolidinedione compounds are well known hypoglycemic agents via increasing insulin-sensitivity. Herein, we provide the possibility that thiazolidinedione compounds could be useful for renal dysfunction through mechanism dependent or independent of its insulin-sensitizing action. In type 2 diabetes, troglitazone could reduce urinary albumin-creatinine ratio compared to metformin. Furthermore, we have shown that troglitazone was able to prevent diabetic glomerular dysfunction through inhibition of diacylglycerol-protein kinase C-extracellular signal-regulated kinase pathway in type 1 diabetic rats. Thus, thiazolidinediones might be effective agents for treating insulin-resistant diabetes as well as diabetes-induced kidney disease.

The sera from GM1 ganglioside antibody positive patients with Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy blocks Na+ currents in rat single myelinated nerve fibers

OBJECTIVE

To determine the possible role of anti-GM1 ganglioside antisera from patients with Gullain-Barr*e syndrome (GBS) or chronic inflammatory demyelinating polyneuropathy (CIDP) in the development of nerve dysfunction.

METHODS

The effect of the anti-GM1 antibody positive antisera obtained from 4 GBS patients and 1 CIDP patient on membrane potential and ionic currents in rat single myelinated nerve fibers was investigated using the voltage clamp technique and compared with that of the anti-GM1 negative antisera obtained from 3 healthy controls and 2 GBS patients.

RESULTS

In the presence of active complement, anti-GM1 positive antisera from 5 patients including 4 GBS patients and 1 CIDP patient significantly suppressed Na+ current more than anti-GM1 negative antisera.

CONCLUSION

This study supports the notion that anti-GM1 antibody is one of the causative factors of conduction abnormality in GBS patients.

Endothelium-specific activation of NAD(P)H oxidase in aortas of exogenously hyperinsulinemic rats

To examine the effects of chronic hyperinsulinemia on vascular tissues, we examined the production of superoxide anion (O(-2)) in the aortic tissues of control and exogenously hyperinsulinemic rats performed by the implantation of an insulin pellet for 4 wk. O(-2) production by aortic segments from hyperinsulinemic rats was 2. 4-fold (lucigenin chemiluminescence method) and 1.7-fold (cytochrome c method) of that of control rats without any differences in O(-2) degrading activities in aortic tissues, respectively (P < 0.025). The increment was completely abolished in the presence of either 100 micromol/l apocynin (an inhibitor of NADPH oxidase) or 10 micromol/l diphenyleneiodonium (an inhibitor of flavin-containing enzyme) and was exclusively endothelium dependent. Consistently, NAD(P)H oxidase activities in endothelial homogenate in hyperinsulinemic rats were dose dependently stimulated above the values of control rats, although these activities in nonendothelial homogenate were not significantly stimulated by insulin. Furthermore, an insulin effect was also demonstrated 1 h after exposing aortic tissues to insulin. These results indicate that O(-2) production specifically increases in endothelium of aortic tissues in chronic hyperinsulinemic rats through the activation of NAD(P)H oxidase.

Prooxidant activity of flavonoids: copper-dependent strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine in DNA

The naturally occurring flavonoids caused strand scission of DNA in the presence of copper ion. Flavonoids such as myricetin, baicalein, and quercetin as well as ascorbic acid cleaved plasmid pBR322 DNA and calf thymus DNA potently. Addition of catalase protected DNA from the strand breaks caused by flavonoids. Treatment of calf thymus DNA with these flavonoids or ascorbate plus copper produced 8-hydroxy-2'-deoxyguanosine. Cuprous ion reduced by flavonoids and ascorbic acid may play a key role in the oxidative cleavage of DNA and the formation of base adduct. Mutagenic and carcinogenic action of flavonoids may be explained by the prooxidant effects of the compounds.