Free radical scavengers improve the impaired endothelium-dependent responses in aorta and kidneys of diabetic rabbits.

The effects of two endogenous antioxidants, alpha-lipoic acid and reduced gluthathione (GSH), were evaluated in the response of the renal vasculature and aortic rings ex vivo of 4-week alloxan-diabetic rabbits to the endothelium-dependent agonists bradykinin (BK) and acetylcholine (Ach) or to the endothelium-independent agonist sodium nitroprusside (SNP) and compared with age and sex-matched euglycemic rabbits. The maximal decrease in perfusion pressure (R(max)) after BK infusion in the renal vasculature from diabetic rabbits was 5.4+/-1.3% (PD(2) 8 [12.6-3.4]) compared with 34.2+/-4.2% (PD(2) 9 [11.3-6.7]) (P<0.05) attained in tissues obtained from euglycemic rabbits. The addition of 1 microM lipoic acid or GSH improved (P<0.05) the R(max) to BK to 18.3+/-2.4% (PD(2) 8.6 [12.4-4.8]) and 19.5+/-3.7% (PD(2) 9.1 [13.3-4.9]), respectively. Similarly, the maximal vasorelaxant response to Ach in kidneys from diabetic rabbits was 16+/-2.0% (PD(2) 7.3 [10.4-4.2] whilst the R(max) in kidneys from euglycemic animals was 52.7+/-4.9% (PD(2) 11.3 [16.4-6.2]). Incubation with 1 microM alpha-lipoic acid or GSH restored the R(max) to Ach to 31+/-3.9% (PD(2) 9.8 [14.3-5.3]) and to 23+/-5.4% (PD(2) 7.6 [11.4-3.8], respectively. The vasodilatory response to SNP was unaltered among tissues from diabetic and euglycemic rabbits and was also unaffected by the treatments utilized. In addition, the R(max) to Ach in aortic rings of diabetic rabbits was 28.7+/-2.4% (PD(2) 8.3 [11.7-4.9]) compared with 100% (PD(2) 7.9 [12.1-3.7]) obtained in tissues gathered from euglycemic rabbits. The pretreatment of the tissues with alpha-lipoic acid restores the R(max) to 47.4+/-4% (PD(2) 11.1 [14.3-7.9]) and the pretreatment with GSH to 52+/-3.2% (PD(2) 9.8 [12.7-6.9]). Similarly, the response to SNP was unaltered in all groups. Lipoic acid and reduced gluthatione directly improved the endothelium-dependent response of renal arterioles and aortic rings of diabetic rabbits.

Gestational diabetes mellitus diagnosed with a 2-h 75-g oral glucose tolerance test and adverse pregnancy outcomes.

OBJECTIVE: To evaluate American Diabetes Association (ADA) and World Health Organization (WHO) diagnostic criteria for gestational diabetes mellitus (GDM) against pregnancy outcomes. RESEARCH DESIGN AND METHODS: This cohort study consecutively enrolled Brazilian adult women attending general prenatal clinics. All women were requested to undertake a standardized 2-h 75-g oral glucose tolerance test (OGTT) between their estimated 24th and 28th gestational weeks and were then followed to delivery. New ADA criteria for GDM require two plasma glucose values > or = 5.3 mmol/l (fasting), > or = 10 mmol/l (1 h), and > or = 8.6 mmol/l (2 h). WHO criteria require a plasma glucose > or = 7.0 mmol/l (fasting) or > or = 7.8 mmol/l (2 h). Individuals with hyperglycemia indicative of diabetes outside of pregnancy were excluded. RESULTS: Among the 4,977 women studied, 2.4% (95% CI 2.0-2.9) presented with GDM by ADA criteria and 7.2% (6.5-7.9) by WHO criteria. After adjustment for the effects of age, obesity, and other risk factors, GDM by ADA criteria predicted an increased risk of macrosomia (RR 1.29, 95% CI 0.73-2.18), preeclampsia (2.28, 1.22-4.16), and perinatal death (3.10, 1.42-6.47). Similarly, GDM by WHO criteria predicted increased risk for macrosomia (1.45, 1.06-1.95), preeclampsia (1.94, 1.22-3.03), and perinatal death (1.59, 0.86-2.90). Of women positive by WHO criteria, 260 (73%) were negative by ADA criteria. Conversely, 22 (18%) women positive by ADA criteria were negative by WHO criteria. CONCLUSIONS: GDM based on a 2-h 75-g OGTT defined by either WHO or ADA criteria predicts adverse pregnancy outcomes.

Capture-recapture method to estimate lower extremity amputation rates in Rio de Janeiro, Brazil.

OBJECTIVE: To estimate rates of lower extremity amputations (LEAs) in persons with peripheral vascular disease, diabetes mellitus, trauma, neoplasm, osteomyelitis, or emphysematous gangrene. METHODS: Regional amputee registries were used to estimate the rate of lower extremity amputations with the capture-recapture (CR) technique. Data were extracted from three amputee registries in Rio de Janeiro: source 1, with 1,191 cases from 23 hospitals; source 2, with 157 cases from a limb-fitting center; and source 3, with 34 cases from a rehabilitation center. Amputee death certificates from source 1 identified 257 deaths from 1992 to 1994. Three CR models were evaluated using sources 2 and 3. In order to avoid an overestimation of the rate of LEAs, two models were applied for the data analysis: in one case, deceased patients listed in source 1 were excluded from the model, and in the other case, deceased patients were included as well. RESULTS: Excluding the 257 deaths, the estimated number of amputations in the municipality of Rio de Janeiro from 1992 to 1994 was 3,954, for a mean annual incidence rate of 13.9 per 100,000 inhabitants. Among persons with diabetes, the annual incidence rate of lower extremity amputations was substantially higher (180.6 per 100,000 persons per year), representing 13 times the risk of individuals without diabetes. The yearly rate of LEAs according to the routine surveillance system was estimated at 5.4 and 96.9 per 100,000 in the general population and in diabetics, respectively. If data from the three registries are added, 1,382 patients with LEAs were identified, with the reasons for the amputations distributed as follows: peripheral vascular disease = 804 (58.1%); diabetes mellitus = 379 (27.4%); trauma = 103 (7.4%); osteomyelitis = 44 (3.1%); gangrene = 36 (2.6%), and neoplasm = 16 (1.1%). CONCLUSIONS: These findings show a high incidence of LEAs in Brazil, when compared to countries such as Spain, that is attributable mainly to peripheral vascular disease and diabetes mellitus.

Decreased endothelium dependent relaxation (nitric oxide) in diabetic kidneys.

To evaluate the endothelium-dependent vasodilatation in diabetic kidneys, we have perfused rabbit kidneys at 30 degrees C with Krebs-Henseleit solution in a non-recirculated perfusion system. To increase vascular tonus, we infused norepinephrine (NOR) (10(-6)M) into the renal artery. After the vasoconstriction reached steady state conditions, a dose-response study was performed with acetylcholine (Ach) and bradykinin (Bk). Administration of Ach (10(-7)M - 10(-5)M) or Bk (10(-8) - 10(-7)M) in cumulative curves through the renal artery promoted a vasodilation, which was dose-dependent in normal and diabetic (three weeks after 150 mg of alloxan, intraperitoneally) kidney. We found a decreased vasodilator response to Ach (p < 0.05) and Bk (p < 0.01) in diabetic animals, when compared to controls. When sodium nitroprusside (10(-8) - 10(-7)M) was administrated through the renal artery to evaluate the endothelium-independent vasodilating effects, a similar vasodilator response was found in both normal and diabetic kidneys. These data indicate for a failure of the vasodilator mechanism dependent on endothelium in alloxan-diabetic kidneys.

Effect of insulin on renal vascular escape in normal and diabetic kidney.

Renal Vascular Escape was studied in the isolated perfused kidney harvested from diabetic and normal rabbits. Diabetes was induced 3-4 weeks earlier by injecting the animals with 150 mg/kg alloxan IP. To induce vasoconstriction, norepinephrine (10(-6) M) (NOR) was infused to the renal artery for 20 min, during 3 cycles, with intervals of 10 min for drug wash out, with a total duration of 90 min of observation. Administration of NOR induced intense vasoconstriction which was followed by a period of relaxation, in spite of the continued infusion of the adrenergic neurohormone. This was named renal vascular escape (RVE). RVE was present in all control animals but was severely impaired in diabetic kidneys. The administration of insulin (20 mU/ml or 2 mU/ml) to the perfusate promoted a significant blockade of escape (p < 0.001) in normal kidneys, which was time dependent, and only a slight effect in the diabetic group. These data show an interaction between insulin and RVE in normal animals and could point out another defect in diabetes, as related to insulin resistance.

Alloxan diabetes blocks noradrenergic tachyphylaxis in the isolated rabbit kidney--effects of insulin.

Normal and alloxan treated diabetic rabbit kidneys were perfused with Krebs-Henseleit solution in a non-recirculating system and the effects of norepinephrine (NOR) 10(-6)M were tested by infusion of this drug for three subsequent periods of 20 min each, with an interval of 10 min for drug wash-out. In the control kidneys the infusion of NOR promoted an intense vasoconstriction, which was less intense during the second and the third periods. This was known as tachyphylaxis. In contrast to the controls, kidneys from diabetic animals did not show tachyphylaxis to NOR, but when insulin was added to the perfusate, tachyphylaxis appeared. Normal kidneys perfused with hyperosmolar solutions show, as in controls, the same phenomenon. The data presented here demonstrate a defect of adrenergic vascular receptors in alloxan treated kidneys, which can be acutely reversed by insulin. These facts are of importance for the understanding of the vascular disease in diabetes.

Insulin blockade of norepinephrine tachyphylaxis in the perfused kidney.

Tachyphylaxis to norepinephrine (NOR) was determined in the rabbit kidney perfused with Krebs-Henseleit solution by using different calcium concentrations (2.5 mM; 5 mM; 12.5 mM) in the perfusate. The addition of insulin to the perfusion fluid causes a reversion of the tachyphylaxis which is seen at those Ca2+ concentrations. This effect is demonstrated mainly at 5 mM Ca2+. When kidneys were perfused with 12.5 mM calcium there was disappearance of NOR-mediated tachyphylaxis, both in the absence and in the presence of insulin. In this calcium concentration, insulin decreases vascular reactivity to NOR. These results suggest that insulin blockade of alpha adrenergic tachyphylaxis is a calcium-mediated effect which is thought to be due to an enhancement of calcium pumping inside the cells.

An alpha-adrenotropic study of the normal and diabetic rabbit kidney.

Rabbit kidneys from normal and alloxan-treated animals were isolated and perfused at 30 degrees C, with Krebs-Henseleit solution. Norepinephrine (NOR), 1 microgram/min, promoted an increase in perfusion pressure which was blocked by phentolamine. In diabetic kidneys NOR induced a sluggish increase in perfusion pressure and resistance, showing a decrease in sensitivity of the adrenergic receptors to the drug. Propranolol, a beta-blocker, was able to elicit an alpha adrenergic blockade in diabetic kidneys. These facts demonstrate an adrenergic receptor defect in diabetic animals, which was shown just three weeks after alloxan treatment.