Effect of irbesartan on nitrotyrosine generation in non-hypertensive diabetic patients

The Role of Angiotensin Receptor Blockers in the Personalized Management of Diabetic Neuropathy

Neuropathy is a frequent complication of diabetes mellitus (DM) and is associated with the increased risk ofamputation and vascular events. Tight glycemic control is an important component inthe prevention of diabetic neuropathy. However, accumulating data suggest that angiotensin receptor blockers (ARBs) might also be useful in this setting. We discuss the findings of both experimental and clinical studies that evaluated the effects of ARBs on indices of diabetic neuropathy. We also review the implicated mechanisms of the neuroprotective actions of these agents. Overall, it appears that ARBs might be a helpful tool for preventing and delaying the progression of diabetic neuropathy, but more data are needed to clarify their role in the management of this overlooked complication of DM.

Nitrotyrosine, Nitrated Lipoproteins, and Cardiovascular Dysfunction in Patients with Type 2 Diabetes: What Do We Know and What Remains to Be Explained?

Diabetes mellitus (DM) is a strong risk factor for the development of cardiovascular diseases (CVDs), which are the most important cause of morbidity and mortality in the population of patients living with DM. DM is associated with lipid metabolism disorders characterized by a decrease in the high-density lipoprotein blood concentration, an increase in the triglyceride blood concentration, and the presence of modified lipoproteins not routinely measured in clinical practice. Nitrated lipoproteins are produced by the nitration of the tyrosyl residues of apolipoproteins by myeloperoxidase. There is some evidence from the research conducted showing that nitrated lipoproteins may play a role in the development of cardiovascular dysfunction, but this issue requires further investigation. It was found that the nitration of HDL particles was associated with a decrease in caspase-3 and paraoxonase-1 activity, as well as a decrease in the activity of cholesterol transport via ABCA1, which reduces the protective effect of HDL particles on the cardiovascular system. Less information has been collected about the role of nitrated LDL particles. Thus far, much more information has been obtained on the relationship of nitrotyrosine expression with the presence of cardiovascular risk factors and the development of cardiovascular dysfunction. The purpose of this paper is to provide an extensive review of the literature and to present the most important information on the current state of knowledge on the association between nitrotyrosine and nitrated lipoproteins with dysfunction of the cardiovascular system, especially in patients living with DM. Moreover, directions for future research in this area were discussed.

A retrospective cohort analysis of the effects of renin-angiotensin system inhibitors on spinal fusion in ACDF patients

BACKGROUND CONTEXT

Recently, preclinical and clinical studies suggest an association between renin-angiotensin system (RAS) blockers and bone healing, particularly in the context of osteoporotic bone fractures.

PURPOSE

To determine the correlation between the use of RAS inhibitors and fusion outcomes and neurologic status in anterior cervical discectomy and fusion (ACDF) surgery.

STUDY DESIGN

Retrospective observational study.

PATIENT SAMPLE

Patients who underwent ACDF for degenerative disorders.

OUTCOME MEASURES

Spinal fusion status and neurologic function (modified Japanese Orthopedic Association [mJOA] and Nurick grading scales).

METHODS

A retrospective chart review was performed, including 200 patients who underwent ACDF for degenerative disorders with 1-year minimum follow-up. Demographic data, comorbidities, antihypertensive medication, neurologic examination, and fusion status were collected. Spinal fusion was assessed via plain cervical x-ray, resorting to dynamic radiographs and/or computer tomography (CT) in cases of uncertainty. Preoperative mJOA and Nurick scores and recovery rates were calculated to determine neurologic status.

RESULTS

Of the 200 patients (42.5% females, 57.5% males, median age of 53.7 years), 82 hypertensive patients were identified. Seventy-seven (93.9%) were taking antihypertensive medication as follows: 36.4% angiotensin-II receptor blockers (ARBs), 35.1% angiotensin-converting enzyme inhibitors (ACEIs), and the remaining patients were taking other medication. In the analysis of fusion rates, patients treated with ARBs exhibited a higher fusion rate, while those treated with ACEIs displayed a lower fusion rate compared to untreated nonhypertensive patients (p = .04 and .02, respectively). The difference in fusion rates between ARBs and ACEIs was also significant, with the former displaying higher rates (p < .001). Smoking exhibited a negative correlation with spinal fusion (p < .001). In the multivariate analysis, ARBs remained an independent factor for successful fusion (p = .02), while smoking remained a risk factor for failed fusion (p = .002). In the neurologic examination, ACEIs, hypertension status, and older age correlated with lower modified Japanese Orthopedic Association (mJOA) recovery rates (p = .001, <.001, and <.001, respectively) in the univariate analysis.

CONCLUSIONS

In ACDF patients, we observed that ARBs were associated with higher fusion rates. Conversely, ACEIs and smoking were related to failed fusion. Prospective case-control studies are needed to confirm these RAS inhibitors effects on spinal fusion.

Renal Function in Type 2 Diabetes Following Gastric Bypass

BACKGROUND

Metabolic surgery for obese patients with type 2 diabetes (T2D) yields short- and long-term remission rates of 60-90%. Its effects on diabetesassociated complications such as neuropathy and nephropathy have not been well studied to date. Hardly any data are available on this subject with respect to moderately obese patients (body mass index [BMI] 25-35 kg/m2) with insulin-dependent T2D. Our previous studies suggest that, in such patients, treatment with a Roux-en-Y gastric bypass (RYGB) improves diabetic neuropathy. In this pilot study, we investigate the course of diabetic nephropathy after RYGB surgery.

METHODS

20 insulin-dependent patients whose T2D was inadequately controlled with medication, and whose BMI was in the range 25-35 kg/m2, were prospectively included in a pilot study. All patients underwent a standardized RYGB operation. Blood and urine tests for renal function were performed before surgery and 12 and 24 months afterward.

RESULTS

The serum creatinine level fell from 0.82 ± 0.23 to 0.69 ± 0.13 mg/dL (p = 0.0025) in the first 12 months after surgery and was unchanged a further 12 months later. The glomerular filtration rate (eGFR) rose in the first 24 months after surgery from 96.4 ± 28.7 to 111.7 ± 23.3 mL/min/1.73 m2 (p = 0.0093). The urinary albumin/creatinine and high-molecular-weight adiponectin/creatinine ratios fell markedly in the first 24 months after surgery (2.89 ± 3.14 versus 1.00 ± 0.24 mg/mmol [p = 0.0491] and 0.18 ± 0.06 versus 0.04 ± 0.01 μg/g [p = 0.0392]).

CONCLUSION

RYGB has positive effects on renal function and may therefore be a good treatment option for moderately obese, insulin-dependent patients whose T2D cannot be adequately controlled with medication. These results still need to be confirmed in randomized, controlled trials with longer periods of followup.

Extracellular microRNAs and endothelial hyperglycaemic memory: a therapeutic opportunity?

Type 2 diabetes mellitus (T2DM) is a major cause of cardiovascular (CV) disease. Several large clinical trials have shown that the risk for patients with diabetes of developing CV complications is only partially reduced by early, intensive glycaemic control and lifestyle interventions, and that such complications result from changes in complex, not fully explored networks that contribute to the maintenance of endothelial function. The accumulation of senescent cells and the low-grade, systemic, inflammatory status that accompanies aging (inflammaging) are involved in the development of endothelial dysfunction. Such phenomena are modulated by epigenetic mechanisms, including microRNAs (miRNAs). MiRNAs can modulate virtually all gene transcripts. They can be secreted by living cells and taken up in active form by recipient cells, providing a new communication tool between tissues and organs. MiRNA deregulation has been associated with the development and progression of a number of age-related diseases, including the enduring gene expression changes seen in patients with diabetes. We review recent evidence on miRNA changes in T2DM, focusing on the ability of diabetes-associated miRNAs to modulate endothelial function, inflammaging and cellular senescence. We also discuss the hypothesis that miRNA-containing extracellular vesicles (i.e. exosomes and microvesicles) could be harnessed to restore a 'physiological' signature capable of preventing or delaying the harmful systemic effects of T2DM.

Nitrosative stress but not glycemic parameters correlate with improved neuropathy in nonseverely obese diabetic patients after Roux-Y gastric bypass

BACKGROUND

Diabetic neuropathy is common in type 2 diabetic patients (T2DM) but tight glycemic control does not improve the symptoms. In contrast, Roux-Y gastric bypass (RYGB) has a positive effect on active neuropathic symptoms, independent from glycemic control. The purpose of the present study was to identify potential mechanisms of improved diabetic neuropathic symptoms after RYGB.

METHODS

A prospective cohort of 20 patients with insulin-dependent T2DM and BMI < 35 kg/m(2) were treated with RYGB. Nineteen patients had complete follow-up. Fasting glucose, HbA1c (glycated hemoglobin), markers for nitrosative, carbonyl, and oxidative stress (nitrotyrosine, carboxylated-lysine (CML), methylglyoxal, oxidized low-density-lipoprotein (oxLDL)) as well as Neuropeptid Y and Neurokinin A were investigated over 12 months. Neuropathy was assessed using the Neuropathy Deficit Score (NDS).

RESULTS

The preoperative NDS improved within twelve months (5.1 ± 0.6 to 2.6 ± 0.4, P = .010). Fasting glucose and HbA1c also improved compared to preoperative values (201.1 ± 16.6 mg/dL to 128 ± 8.7 mg/dL, P = .004 and 8.5 ± 0.3% (53 ± 3.3 mmol/mol) to 7 ± 0.3% (67 ± 3.3 mmol/mol), P = .001, respectively). Nitrotyrosine, CML, and methylglyoxal all 3 decreased postoperatively (1067.3 ± 266.9 nM to 355.8 ± 36.4 nM, P = .003; 257.1 ± 10.2 ng/ml to 215.3 ± 18.3 ng/ml, P = .039; 402.3 ± 3.9 nM to 163.4 ± 10.3 nM, P = .002). OxLDL remained unchanged. Fasting glucose and HbA1c did not correlate with improved neuropathy. The decrease in nitrotyrosine correlated with improvement in the NDS after 6 and twelve months (r = .9, P < .001 and r = .68, P = .03). The decrease in methylglyoxal after 6 months correlated with decrease in NDS after twelve months (r = 0.897, P = .003).

CONCLUSION

RYGB seems to improve oxidative, nitrosative and carbonyl stress, known to have a causal role in diabetic neuropathy.

Regulatory networks and complex interactions between the insulin and angiotensin II signalling systems: models and implications for hypertension and diabetes

The cross-talk between insulin and angiotensin II signalling pathways plays a significant role in the co-occurrence of diabetes and hypertension. We developed a mathematical model of the system of interactions among the biomolecules that are involved in the cross-talk between the insulin and angiotensin II signalling pathways. We have identified several feedback structures that regulate the dynamic behavior of the individual signalling pathways and their interactions. Different scenarios are simulated and dominant steady-state, dynamic and stability characteristics are revealed. The proposed mechanistic model describes how angiotensin II inhibits the actions of insulin and impairs the insulin-mediated vasodilation. The model also predicts that poor glycaemic control induced by diabetes contributes to hypertension by activating the renin angiotensin aystem.

Autonomic imbalance: prophet of doom or scope for hope?

It has long been recognized that cardiac autonomic neuropathy increases morbidity and mortality in diabetes and may have greater predictive power than traditional risk factors for cardiovascular events. Significant morbidity and mortality can now be attributable to autonomic imbalance between the sympathetic and parasympathetic nervous system regulation of cardiovascular function. New and emerging syndromes include orthostatic tachycardia, orthostatic bradycardia and an inability to use heart rate as a guide to exercise intensity because of the resting tachycardia. Recent studies have shown that autonomic imbalance may be a predictor of risk of sudden death with intensification of glycaemic control. This review examines an association of autonomic dysregulation and the role of inflammatory cytokines and adipocytokines that promote cardiovascular risk. In addition, conditions of autonomic imbalance associated with cardiovascular risk are discussed. Potential treatment for restoration of autonomic balance is outlined.

Deterioration of glomerular endothelial surface layer induced by oxidative stress is implicated in altered permeability of macromolecules in Zucker fatty rats

AIMS/HYPOTHESIS

The glomerular endothelial layer is coated by the endothelial surface layer (ESL), which is suggested to play a role in regulation of the permselectivity of macromolecules. Production of heparanase, a degrading enzyme of the ESL, is induced by reactive oxygen species (ROS). We hypothesised that oxidative stress could cause deterioration of the glomerular ESL by induction of heparanase, resulting in increased glomerular permeability.

METHODS

Male Zucker fatty (ZF) rats with albuminuria and Zucker lean (ZL) rats were used in this study. Some of the ZF rats were treated with the angiotensin II receptor blocker, irbesartan. We determined the amount of ESL by wheat germ agglutinin staining and heparan sulphate proteoglycan production by western blot analysis. Glomerular hyperfiltration of macromolecules was visualised using in vivo microscopy. We used 2',7'-dichlorofluorescein diacetate-derived chemiluminescence staining to assess ROS production, and heparanase production and expression were determined by western blot analysis and quantitative real-time polymerase chain reaction respectively.

RESULTS

By 18 weeks of age, ZF rats had developed albuminuria. The glomerular endothelial cell glycocalyx was significantly decreased in ZF compared with ZL rats. Glomerular filtration and the permeability of macromolecules were increased in ZF, but not in ZL rats. Glomerular ROS and heparanase production were significantly increased in ZF compared with ZL rats. These changes in ZF rats were reversed by irbesartan treatment.

CONCLUSIONS/INTERPRETATION

Increased oxidative stress induces glomerular ESL deterioration in part through increased heparanase levels, resulting in exacerbation of glomerular permselectivity and development of albuminuria.

Persistent correction of hyperglycemia in streptozotocin-nicotinamide-induced diabetic mice by a non-conventional radical scavenger

We previously reported that in a diabetes mouse model, characterised by moderate hyperglycaemia and reduced β-cell mass, the radical scavenger bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decandioate di-hydrochloride (IAC), a non-conventional cyclic hydroxylamine derivative, improves metabolic alterations by counteracting β-cell dysfunction associated with oxidative stress. The aims of this study were to ascertain whether the beneficial effects of IAC treatment could be maintained after its discontinuation and further elucidate the underlying mechanisms. Diabetes was induced in C57Bl/6J mice by streptozotocin (STZ) and nicotinamide (NA) administration. Diabetic mice were treated for 7 weeks with various doses of IAC (7.5, 15, or 30 mg/kg b.w./die i.p.) and monitored for additional 8 weeks after suspension of IAC. Then, pancreatic tissue was used for determination of β-cell mass by immunohistochemistry and β-cell ultrastructural analysis. STZ-NA mice showed moderate hyperglycaemia, glucose intolerance and reduced β-cell mass (25% of controls). IAC-treated STZ-NA mice (at both doses of 15 and 30 mg/kg b.w.) showed long-term reduction of hyperglycaemia even after discontinuation of treatment, attenuation of glucose intolerance and partial preservation of β-cell mass. The lowest IAC dose was much less effective. Plasma nitrotyrosine levels (an oxidative stress index) significantly increased in untreated diabetic mice and were lowered upon IAC treatment. At ultrastructural level, β cells of IAC-treated diabetic mice were protected against degranulation and mitochondrial alterations. In the STZ-NA diabetic mouse model, the radical scavenger IAC induces a prolonged reduction of hyperglycaemia associated with partial restoration of β-cell mass and function, likely dependent on blockade of oxidative stress-induced damaging mechanisms.

Angiotensin II inhibits insulin-stimulated GLUT4 translocation and Akt activation through tyrosine nitration-dependent mechanisms

Angiotensin II (Ang II) plays a major role in the pathogenesis of insulin resistance and diabetes by inhibiting insulin's metabolic and potentiating its trophic effects. Whereas the precise mechanisms involved remain ill-defined, they appear to be associated with and dependent upon increased oxidative stress. We found Ang II to block insulin-dependent GLUT4 translocation in L6 myotubes in an NO- and O₂^.−-dependent fashion suggesting the involvement of peroxynitrite. This hypothesis was confirmed by the ability of Ang II to induce tyrosine nitration of the MAP kinases ERK1/2 and of protein kinase B/Akt (Akt). Tyrosine nitration of ERK1/2 was required for their phosphorylation on Thr and Tyr and their subsequent activation, whereas it completely inhibited Akt phosphorylation on Ser⁴⁷³ and Thr³⁰⁸ as well as its activity. The inhibitory effect of nitration on Akt activity was confirmed by the ability of SIN-1 to completely block GSK3α phosphorylation in vitro. Inhibition of nitric oxide synthase and NAD(P)Hoxidase and scavenging of free radicals with myricetin restored insulin-stimulated Akt phosphorylation and GLUT4 translocation in the presence of Ang II. Similar restoration was obtained by inhibiting the ERK activating kinase MEK, indicating that these kinases regulate Akt activation. We found a conserved nitration site of ERK1/2 to be located in their kinase domain on Tyr^156/139, close to their active site Asp^166/149, in agreement with a permissive function of nitration for their activation. Taken together, our data show that Ang II inhibits insulin-mediated GLUT4 translocation in this skeletal muscle model through at least two pathways: first through the transient activation of ERK1/2 which inhibit IRS-1/2 and second through a direct inhibitory nitration of Akt. These observations indicate that not only oxidative but also nitrative stress play a key role in the pathogenesis of insulin resistance. They underline the role of protein nitration as a major mechanism in the regulation of Ang II and insulin signaling pathways and more particularly as a key regulator of protein kinase activity.

Nitrosylated proteins in monocytes as a new marker of oxidative-nitrosative stress in diabetic subjects with macroangiopathy

BACKGROUND

Peroxynitrite plays an important role in the pathogenesis of diabetic complications. Nitrosylated protein expression in peripheral blood monocytes reflects intracellular peroxynitrite injury, and thus could be a marker of higher diagnostic and prognostic value than plasma nitrotyrosine level. The purpose of this pilot study was to assess if peripheral blood monocytes of diabetic subjects accumulate nitrosylated proteins, and if nitrosylated protein expression correlates with blood glucose control, variables of lipid profile, C-reactive protein concentration (a marker of inflammation), and differs in patients with and without diabetic macrovascular and microvascular complications.

METHODS

Nitrosylated protein expression in peripheral blood monocytes (Western blot analysis) was assessed in 31 subjects with diabetes mellitus (29 Type 2, 2 Type 1; 20 males, 11 females; mean age 66 years). The presence of microangiopathy was defined by retinopathy, albumin excretion, and/or neuropathy, and macroangiopathy by carotid plaques, a history of myocardial infarction, and/or stroke.

RESULTS

Diabetic subjects accumulated significant amounts of nitrosylated proteins in peripheral blood monocytes. Nitrosylated protein expression positively correlated with body weight, blood glucose, HbA (1)C, and plasma C-reactive protein concentrations in the whole cohort as well as in subjects with diabetic macroangiopathy.

CONCLUSIONS

Monocyte nitrosylated protein expression is a new biomarker of metabolic control and inflammation in diabetic subjects with macroangiopathy. A more detailed assessment of diabetic microvascular complications in a larger group of patients is needed to determine if this variable can be employed as a biomarker of the presence, severity, and progression of diabetic neuropathy, retinopathy, and nephropathy.

White blood cells telomere length is shorter in males with type 2 diabetes and microalbuminuria

OBJECTIVE

To examine differences in telomere (terminal restriction fragment [TRF]) length and pulse wave velocity (PWV)--an index of arterial stiffness--in patients with type 2 diabetes with and without microalbuminuria (MA).

RESEARCH DESIGN AND METHODS

A total of 84 men with type 2 diabetes, 40 with MA and 44 without MA (aged 63.5 +/- 9.0 vs. 61.2 +/- 9.8 years), were studied. TRF length was determined in white blood cells. MA was defined as albumin excretion rate (AER) in the range of 30-300 mg/24 h in at least two of three 24-h urine collections. PWV was assessed using applanation tonometry. Markers of oxidative stress were also measured.

RESULTS

TRF length was shorter in patients with MA than in those without MA (6.64 +/- 0.74 vs. 7.23 +/- 1.01 kb, respectively, P = 0.004). PWV was significantly higher in the patients with MA. Multivariate linear regression analysis in the total sample demonstrated an independent association between TRF length and age (P = 0.02), MA status (P = 0.04) or AER (P = 0.002), and plasma nitrotyrosine levels (P = 0.02). AER was associated significantly with PWV (P < 0.01).

CONCLUSIONS

Subjects with type 2 diabetes and MA have shorter TRF length and increased arterial stiffness than those without MA. Additionally, TRF length is associated with age, AER, and nitrosative stress. As shorter TRF length indicates older biological age, the increased arterial stiffness in patients with type 2 diabetes who have MA may be due to the more pronounced "aging " of these subjects.

Telmisartan shows an equivalent effect of vitamin C in further improving endothelial dysfunction after glycemia normalization in type 1 diabetes

OBJECTIVE

Long-lasting hyperglycemia in type 1 diabetic patients induces permanent alterations of endothelial function by increased oxidative stress, even when glycemia is normalized.

RESEARCH DESIGN AND METHODS

In this study, 36 type 1 diabetic patients and 12 control subjects were enrolled. The diabetic patients were divided into three groups. The first group was treated for 24 h with insulin, achieving a near normalization of glycemia. After 12 h of this treatment, vitamin C was added for the remaining 12 h. The second group was treated for 24 h with vitamin C. After 12 h of this treatment, insulin was started, achieving a near normalization of glycemia for the remaining 12 h. The third group was treated for 24 h with both vitamin C and insulin, achieving near normalization of glycemia. The same protocols were performed after 1 month of telmisartan or placebo.

RESULTS

Neither normalization of glycemia nor vitamin C treatment alone was able to normalize endothelial dysfunction or oxidative stress. Combining insulin and vitamin C normalized endothelial dysfunction and decreased oxidative stress to normal levels. Telmisartan significantly improved basal endothelial function and decreased nitrotyrosine plasma levels. In patients treated with telmisartan, a near normalization of both flow-mediated vasodilation and oxidative stress was achieved when glycemia was normalized, whereas adding vitamin C infusion did not show further effect on endothelial function or nitrotyrosine plasma levels.

CONCLUSIONS

These data indicate that combining the normalization of glycemia with an antioxidant can normalize endothelial function in type 1 diabetic patients and that telmisartan works as an antioxidant like vitamin C.

Effects of low- and high-advanced glycation endproduct meals on macro- and microvascular endothelial function and oxidative stress in patients with type 2 diabetes mellitus

BACKGROUND

An advanced glycation endproducts (AGEs)-rich diet induces significant increases in inflammatory and endothelial dysfunction markers in type 2 diabetes mellitus (T2DM).

OBJECTIVE

The aim was to investigate the acute effects of dietary AGEs on vascular function in T2DM patients.

DESIGN

Twenty inpatients with T2DM [x (+/-SEM) age: 55.4 +/- 2.2 y; glycated hemoglobin: 8.8 +/- 0.5%] were investigated. In a randomized crossover design, the effects of a low-AGE (LAGE) and high-AGE (HAGE) meal on macrovascular [by flow-mediated dilatation (FMD)] and microvascular (by Laser-Doppler flowmetry) function, serum markers of endothelial dysfunction (E-selectin, intracellular adhesion molecule 1, and vascular cell adhesion molecule 1), oxidative stress, and serum AGE were assessed. The meals had identical ingredients but different AGE amounts (15.100 compared with 2.750 kU AGE for the HAGE and LAGE meals, respectively), which were obtained by varying the cooking temperature and time. The measurements were performed at baseline and 2, 4, and 6 h after each meal.

RESULTS

After the HAGE meal, FMD decreased by 36.2%, from 5.77 +/- 0.65% (baseline) to 3.93 +/- 0.48 (2 h), 3.70 +/- 0.42 (4 h), and 4.42 +/- 0.54% (6 h) (P<0.01 for all compared with baseline). After the LAGE meal, FMD decreased by 20.9%, from 6.04 +/- 0.68% (baseline) to 4.75 +/- 0.48% (2 h), 4.69 +/- 0.51% (4 h), and 5.62 +/- 0.63% (6 h), respectively (P<0.01 for all compared with baseline; P<0.001 for all compared with the HAGE meal). This impairment of macrovascular function after the HAGE meal was paralleled by an impairment of microvascular function (-67.2%) and increased concentrations of serum AGE and markers of endothelial dysfunction and oxidative stress.

CONCLUSIONS

In patients with T2DM, a HAGE meal induces a more pronounced acute impairment of vascular function than does an otherwise identical LAGE meal. Therefore, chemical modifications of food by means of cooking play a major role in influencing the extent of postprandial vascular dysfunction.

Importance of hereditary haemochromatosis in the care of diabetes mellitus

Szerzők a vas- és a szénhidrátanyagcsere kapcsolatait vizsgálták saját és irodalmi eredmények tükrében. Különös hangsúlyt fektettek a szabad gyökös folyamatok ismertetésére, mivel a hereditaer haemochromatosis és a diabetes mellitus is, mint a vas- és a szénhidrátanyagcsere-zavarok leggyakoribbjai oxidatív stressz keltése révén vezetnek szövődményekhez. A nagy vér és szöveti glükózkoncentráció elektronfelesleget eredményez. Ez redukálhatja a redox ciklusban részt vevő, transzport- vagy raktárfehérjéhez nem kötött vasat, és ez vezet az oxidatív stresszhez. A hereditaer haemochromatosis mind a válogatás nélküli, mind pedig a diabeteses populációban a szöveti redox-aktív vas szintjének emelkedését okozhatja. A hereditaer haemochromatosis leggyakoribb mutációit hordozók aránya hazánkban, szelekció nélküli népességben 30,4%-ot és diabetesben 35,8%-ot tesz ki. Az irodalom adatai szerint feltételezhető, hogy már a hereditaer haemochromatosis leggyakoribb mutációi (HFE-C282Y és HFE-H63D) szempontjából heterozigotákban is megemelkedik a szöveti vasszint, bár a fenotípusban a hereditaer haemochromatosis ilyenkor általában nem jelenik meg, mivel penetranciája alacsony. Mégis, ez a megemelkedett vas-ellátottság a már más okból – például diabetes mellitus miatt – károsodott szövetek betegségének progresszóját okozhatja. Másrészt a hereditaer haemochromatosis olyan endothelkárosodáshoz vezethet, ami miatt – a diabetes mellitus manifesztálódását megelőzően – hypertonia alakulhat ki. Feltételezhető, hogy a vérnyomásemelkedés a hereditaer haemochromatosis egyik legkorábbi klinikai jele. Nehezen beállítható hypertonia és szénhidrátanyagcsere-zavar esetén érdemes gondolni a hereditaer haemochromatosis lehetőségére.

Effect of atorvastatin and irbesartan, alone and in combination, on postprandial endothelial dysfunction, oxidative stress, and inflammation in type 2 diabetic patients

BACKGROUND

Postprandial hypertriglyceridemia and hyperglycemia are considered risk factors for cardiovascular disease. Evidence suggests that postprandial hypertriglyceridemia and hyperglycemia induce endothelial dysfunction and inflammation through oxidative stress. Statins and angiotensin type 1 receptor blockers have been shown to reduce oxidative stress and inflammation, improving endothelial function.

METHODS AND RESULTS

Twenty type 2 diabetic patients ate 3 different test meals: a high-fat meal, 75 g glucose alone, and a high-fat meal plus glucose. Glycemia, triglyceridemia, endothelial function, nitrotyrosine, C-reactive protein, intercellular adhesion molecule-1, and interleukin-6 were assayed during the tests. Subsequently, diabetics took atorvastatin 40 mg/d, irbesartan 300 mg/d, both, or placebo for 1 week. The 3 tests were performed again between 5 and 7 days after the start of each treatment. High-fat load and glucose alone produced a decrease in endothelial function and increases in nitrotyrosine, C-reactive protein, intercellular adhesion molecule-1, and interleukin-6. These effects were more pronounced when high-fat load and glucose were combined. Short-term atorvastatin and irbesartan treatments significantly counterbalanced these phenomena, and their combination was more effective than either therapy alone.

CONCLUSIONS

This study confirms an independent and cumulative effect of postprandial hypertriglyceridemia and hyperglycemia on endothelial function and inflammation, suggesting oxidative stress as a common mediator of such an effect. Short-term treatment with atorvastatin and irbesartan may counterbalance this phenomenon; the combination of the 2 compounds is most effective.