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Background Non-insulin-dependent diabetes mellitus (NIDDM) and hyperhomocysteinemia are both associated with increased lipid peroxidation (oxidative stress). This may contribute to the accelerated vascular disease associated with these conditions. It is not known whether the coexistence of elevated homocysteine levels will stimulate oxidative stress further than that caused by diabetes alone. Methods Plasma concentrations of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, were measured in patients with NIDDM who had previously had a methionine load test; some of the patients had hyperhomocysteinemia. Results Plasma TBARS concentrations were elevated in diabetics with vascular disease. The additional presence of hyperhomocysteinemia was not associated with a further increase in plasma TBARS concentrations. Conclusions Lipid peroxidation is increased in patients with diabetes mellitus and macrovascular disease and is not further elevated by the coexistence of elevated homocysteine levels. It is possible that diabetes maximally stimulates oxidative stress and any further acceleration of vascular disease in patients who have coexistent hyperhomocysteinemia is mediated through mechanisms other than lipid peroxidation.

To assess whether, in the treatment of non-insulin-dependent diabetes mellitus (NIDDM), (1) metformin in conjunction with insulin can safely cause a decrease in glycosylated hemoglobin (HbA1c) to 7% or less and (2) this combination therapy may result in weight loss and lower insulin dose in comparison with insulin treatment alone.Forty patients with NIDDM being treated with insulin on their first visit to the Diabetes Center were identified by retrospective review of medical records of all patients encountered during a 1-year period. These patients were classified into groups who were receiving insulin only (group 1) or insulin + metformin (group 2) at the most recent visit. Group 2 was subdivided into those with a body mass index of either =30 kg/m 2 (group 2A) or30 kg/m 2 (group 2B). Blood glucose, HbA1c, insulin dose, and weights were analyzed from their initial and most recent visits.HbA1c decreased from 10 +/- 2.7% to 7 +/- 1.1% (P0.01) in group 1 and from 9.8 +/- 2.1% to 7.2 +/- 1.4% (P0.01) in group 2. The magnitude of decrease in HbA1c, however, was not different between the two groups. Total insulin dose increased from 40 (33 to 50) U/day to 58 (41 to 67) U/day (P0.05) in group 1 and from 63 (42 to 118) U/day to 67 (50 to 96) U/day in group 2 (not significantly different). The median increase in insulin dose was 8 U in group 1, whereas the median decrease was 3 U in group 2 (P0.05). Similar decreases were noted in group 2A. The decrease in insulin dose was inversely related to the initial insulin dose per kilogram of body weight in group 2 (r = -0.5; P0.01). Patients in group 1 had an increase in weight from 75.0 +/- 8.6 kg to 77.7 +/- 9.0 kg (P0.01), whereas weight decreased from 100.4 +/- 24.2 kg to 98.5 +/- 22.3 kg in group 2 (P0.05). A decrease in weight was seen even in group 2A. The increase in weight was 3 +/- 3.3 kg in group 1, whereas weight decreased by 1.9 +/- 3.9 kg in group 2 (P0.01).Insulin + metformin is safe and is as effective as insulin alone in improving glycemic control in obese and nonobese patients with NIDDM. This combination therapy, however, lowers insulin dose and promotes weight loss, which may be of importance in decreasing the cardiovascular risk factors in these subjects.

To determine whether hydrocortisone given intravenously inhibits reactive oxygen species (ROS) generation by polymorphonuclear neutrophils (PMNLs) in vivo and, if so, to describe the pharmacodynamics of this effect.A prospective, open label study in normal subjects.A clinical research unit of a tertiary referral center for diabetes and endocrinology.Eight normal subjects (age range, 2450 yrs).An indwelling cannula was inserted into the antecubital vein. Sequential blood samples were obtained from the cannula just before, and after, the intravenous injection of hydrocortisone (100 mg) at 1, 2, 4, 8, and 24 hrs.ROS generation by PMNLs and mononuclear cells (MNCs) was assayed as previously observed in a chemiluminometer. ROS generation by PMNLs and MNCs was inhibited by hydrocortisone at 1 hr; this effect peaked at 2 hrs and began to recover by 4 hrs; ROS generation had recovered to the baseline by 24 hrs. Although the pharmacodynamic effect of hydrocortisone on PMNLs and MNCs was similar, the peak inhibition was significantly greater for PMNLs (26% of basal vs. 43% of basal, p.02) than MNCs.There is a marked, consistent, inhibition of ROS generation by PMNLs, which parallels that of MNCs after intravenous hydrocortisone. The pharmacodynamics of this effect are consistent with our current clinical practices.

Since an increase in tumor necrosis factor alpha (TNFalpha) expression has been associated with insulin resistance, this study was undertaken to determine the status of circulating TNFalpha and the relationship of TNFalpha with insulin levels, body weight, or both in women with polycystic ovary syndrome (PCOS). Fasting serum samples were analyzed in 34 subjects with PCOS, of whom 22 were obese (body mass index [BMI]>27 kg/m2), and in 40 normal control women, of whom 20 were obese. Women with PCOS exhibited a significantly (P

In view of the recent demonstration that obesity in animals and humans is associated with an increase in tumor necrosis factor-α (TNFα) expression, that this expression falls with weight loss, and that TNFα may specifically inhibit insulin action, the possibility that TNFα may be a mediator of insulin resistance has been raised. We have undertaken this study to investigate whether serum TNFα concentrations are elevated in obese subjects, whether they fall after weight loss, and whether this fall parallels the fall in insulin release after glucose challenge. Obese patients (age range: 25–54, weight mean ± sd: 96.4 ± 13.8 kg, body mass index: 35.7 ± 5.6 kg/m2) were started on a diet program. The mean weight fell to 84.5 ± 11.3 (P < 0.0001) and body mass index to 31.3 ± 4.9 (P < 0.0001). Plasma TNFα concentrations were markedly elevated in the obese (3.45 ± 0.16 pg/mL), when compared with controls (0.72 ± 0.28 pg/mL), and fell significantly (2.63 ± 1.40 pg/mL) after weight loss (P < 0.02). The magnitude of insulin release after glucose (75 g) challenge (area under the curve) also fell significantly (P < 0.01) after weight loss. The magnitude of weight loss and fall in TNFα were related to basal body weight (r = 0.57, P < 0.001) and basal TNFα (r = 0.55, P < 0.001) concentrations, respectively, but not to each other or to the glucose-induced insulin release (area under the curve). We conclude that obesity is associated with increased plasma TNFα concentrations, which fall with weight loss. Because circulating TNFα may mediate insulin resistance in the obese, a fall in TNFα concentrations may contribute to the restoration of insulin resistance after weight loss, Thus, TNFα may be an important circulating cytokine, which may provide a potentially reversible mechanism for mediating insulin resistance.

Corticosteroids are known to exert antiinflammatory and immunosuppressive effects. Since reactive oxygen species (ROS) induce tissue damage and inflammation and since mononuclear cells (MNCs) generate ROS, we investigated whether corticosteroids inhibit ROS generation by MNCs when given systemically. A single dose of either 300 mg (n = 8) or 100 mg (n = 6) of hydrocortisone (HC) was injected intravenously into eight and six subjects, respectively. Blood samples were obtained before and sequentially after the injection. Following 300 mg HC, N-formylmethionyl leucyl phenylalanine (fMLP)-induced ROS generation, assayed by measuring chemiluminescence with luminol, decreased significantly at 0.5 hours and reached a nadir at 2 hours (8% of basal, P < .001); thereafter, it gradually recovered, but was still below baseline at 24 hours. Following the dose of 100 mg HC, ROS generation decreased significantly at 1 hour (nadir, 30% of basal; P < .01) and gradually recovered to near basal level at 8 hours. Serum cortisol concentrations were markedly elevated over basal and remained elevated throughout the first 8 hours of the experiment, returning to baseline at 24 hours. This inhibition of ROS generation by HC (and other glucocorticoids) may have a role to play in mediating the antiinflammatory action of corticosteroids.

Hyperoxia increases pulmonary damage after acid aspiration. We hypothesize that free radicals play a role in acute lung injury. To examine this hypothesis, we injured rats by intratracheal instillation of acidic isotonic sodium chloride solution (NS) (pH 1.25); NS + gastric particles (particle pH 5.3); or acid + particles (pH 1.25). Animals were exposed to 98% oxygen or air for 5 h. Superoxide (HO2) generation was measured in either an aliquot of white blood cells (WBCs) recovered from bronchoalveolar lavage (BAL) or from blood. Lungs were analyzed for thiobarbituric acid-reactive substances (TBARS) and carbonylated proteins. The antioxidant capacity was measured using a 2-2'-azo-bis-amidinopropane hydrochloride neutralizing assay. Generation of HO2 by WBCs in peripheral blood was greater in animals exposed to 98% O2 (89.8 +/- 12.5 U. min-1.10(5) neutrophils) compared with air exposure (37.5 +/- 9.2 U.min-1.10(5) neutrophils) after combined injury (P0.05). Similarly, HO2 generation by WBCs retrieved from BAL was higher in oxygen-exposed rats (987.74 +/- 128 U.min-1.10(5) WBC) compared with air-exposed animals after an identical injury (348 +/- 9.2 U. min-1.10(5) WBC) (P0.05). TBARS and carbonylated protein levels in the lungs of oxygen-exposed animals (587.9 +/- 58.6 and 55.8 +/- 3.1 pmol/mg of protein, respectively) were higher than those in air-exposed rats after combined injury (342.8 +/- 15.1 and 28.6 +/- 4.6 pmol/mg of protein, respectively) and compared with air-exposed uninjured rats (340.6 +/- 9.8 and 18.3 +/- 2.8 pmol/mg of protein, respectively; P0.01). Antioxidant capacity decreased in acid and combined injury groups (2.41 +/- 0.13 min and 1.94 +/- 0.15 min, respectively) compared with the uninjured group after 5 h of exposure to 98% oxygen (4.85 +/- 0.19 min; P0.01). We demonstrated evidence of increased oxidant activity on lipids and proteins in injured lungs after oxygen exposure. The decrease in antioxidant capacity after low pH aspiration with exposure to hyperoxia may contribute to this increase.Oxygen administration results in a lung pathology known as oxygen toxicity. This effect is usually not significant if the duration of exposure is limited to24 h. In the presence of acute inflammatory lung injury, exposure to hyperoxia results in lung damage in a shorter time. We demonstrate that sufficiently decreased lung antioxidant reserve capacity may be accountable for this early toxicity.

The authors investigated whether amelioration of intestinal mucosal injury, due to ischemia-reperfusion (I/R), with oxygenated perfluorocarbon (PFC) would reduce an oxidant-generated lung injury. The small intestine is increasingly recognized as a primary effector of distant organ injury. Clinical and experimental studies suggest oxidant species and activated neutrophils as the agents responsible for lung injury after intestinal I/R. The role of intestinal mucosal injury has not been defined. Oxygenated PFC was perfused through the lumen of the intestine during periods of I/R. Portal venous effluent was examined for reactive oxygen species and lung tissue was examined for lipid peroxidation. Luminal perfusion of oxygenated PFC during intestinal I/R reduced oxidant species in the portal blood. This correlated with a reduction in lung lipid peroxidation. Oxygenated PFC prevented intestinal mucosal injury resulting from induced I/R. Amelioration of mucosal injury reduced oxidant generation in the portal venous circulation that was proportional to the reduction in measured lung injury. Protection of the mucosa with intraluminal oxygen may prevent I/R-associated lung injury.

Increased production of reactive oxygen species (ROS) and lipid peroxidation may contribute to vascular complications in diabetes. to test whether DNA is also oxidatively damaged in diabetes, we measured 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative damage of DNA, in mononuclear cells.For this laboratory-based study, 12 patients with insulin-dependent diabetes mellitus (IDDM) and 15 patients with non-insulin-dependent diabetes mellitus (NIDDM) were matched by age with ten healthy volunteers each. DNA was extracted from mononuclear cells from whole blood. 8-OHdG was assayed by high-pressure liquid chromatography, and ROS were assayed by chemiluminescence.IDDM and NIDDM patients had significantly higher median concentrations (p , 0.001, U test) of 8-OHdG in their mononuclear cells than their corresponding controls (in fmol/micrograms DNA): 128.2 (interquartile range 96.0-223.2) and 95.2 (64.0-133.5) vs 28.2 (21.7-43.4) and 21.9 (18.0-24.4), respectively. ROS generation by mononuclear cells was also significantly greater (p0.01) in diabetic patients than in their controls (in mV): 238.0 (107.0-243.0) and 101.3 (66.0-134.0) vs 69.5 (49.8-91.9) and 56.0 (38.8-62.5), respectively.IDDM and NIDDM patients showed greater oxidative damage to DNA, with increased generation of ROS, than controls. Such changes might contribute to accelerated aging and atherogenesis in diabetes and to the microangiopathic complications of the disease.

Objective : To determine whether reactive oxygen metabolite production by alveolar macrophages is affected by liquid perfluorochemical exposure. Design : Controlled, animal laboratory investigation of alveolar macrophage function in vitro. Setting : Animal research facility of a health sciences university. Subjects : Six adult male New Zealand white rabbits and six young piglets. Interventions : Alveolar macrophages were obtained after sacrifice from both species by total lung lavage. Macrophages were divided into control and experimental groups. Macrophages in the experimental groups were exposed to perfluorooctylbromide. To determine production of reactive oxygen metabolites, hydrogen peroxide production and chemiluminescence were measured in both experimental and control groups after chemical stimulation. Measurements and Main Results : Perfluorooctylbromide-exposed alveolar macrophages produced significantly less hydrogen peroxide (1.4 ± 1.5 vs. 2.4 ± 1.6 nmol/10 6 cells ; p = .002). Perfluorooctylbromide-exposed alveolar macrophages demonstrated significantly less chemiluminescence activity compared with nonexposed cells (0.70 ± 0.2 vs. 1.5 ± 0.2 mV of relative activity per 3.5 x 10 5 cells ; p =.005). Conclusions : Exposure of alveolar macrophages to perfluorooctylbromide in vitro decreases the responsiveness of macrophages to potent stimuli. This finding may partially explain the decrease in pulmonary inflammation seen in animals treated with partial liquid ventilation during experimentally induced lung injury. (Crit Care Med 1995 ; 23 :1533-1539)