Effect of moderate-to-severe chronic kidney disease on flow-mediated dilation and progenitor cells

Exercise for chronic kidney disease: effects on vascular and cardiopulmonary function

Patients with chronic kidney disease (CKD) have an exacerbated prevalence of cardiovascular disease (CVD). Vascular dysfunction, characterized by impaired endothelial function and arterial stiffness, and markedly low cardiorespiratory fitness levels are hallmark manifestations of the disease that contribute to the CVD burden. Despite advancements in blood pressure and lipid lowering pharmacological therapies, CVD remains markedly prevalent across the spectrum of CKD. This highlights a stagnation in effective clinical strategies to improve cardiovascular health and reinforces the critical need for adjuvant lifestyle strategies such as physical activity and exercise training to be incorporated into routine clinical care. This narrative review provides an overview of the known effects of exercise on vascular and cardiopulmonary function across the spectrum of CKD. The physiological mechanisms of vascular dysfunction that serve as exercise-specific therapeutic targets are highlighted and future perspectives are discussed.

Aerobic Exercise Attenuates Kidney Injury, Improves Physical Performance, and Increases Antioxidant Defenses in Lungs of Adenine-Induced Chronic Kidney Disease Mice

The association between chronic kidney disease (CKD) and pulmonary pathophysiological changes is well stablished. Nevertheless, the effects of aerobic exercise (AE) on lungs of CKD need further clarification. Thus, Swiss mice were divided in control, AE, CKD, and CKD + AE groups. CKD was induced by 0.2% adenine intake during 8 weeks (4 weeks of CKD induction and 4 weeks of AE). AE consisted in running on treadmill, at moderate intensity, 30 min/day, 5 days/week, during 4 weeks. Twenty-four hours after the last training day, functional capacity test was performed, and 48 h after the test, mice were euthanized. CKD mice showed a significant increase in urine output, serum urea, and creatinine concentrations, and decreased body weight and urine density, besides oxidative damage (p = 0.044), edema area (p < 0.001), leukocyte infiltration (p = 0.040), and collagen area in lung tissue (p = 0.004). AE resulted in an increase of distance traveled (p = 0.049) and maximum speed (p = 0.046), increased activity of catalase (p = 0.031) and glutathione peroxidase (p = 0.048) in lungs, increased levels of nitric oxide (NOx) in serum (p = 0.001) and bronchoalveolar lavage fluid (p = 0.047), and decreased kidney histological injury (p = 0.018) of CKD mice. However, AE also increased oxidative damage (p = 0.003) and did not change collagen content or perivascular edema in lungs (p > 0.05) of CKD mice. Therefore, AE attenuated kidney injury and improved antioxidants defenses in lungs. Despite no significant changes in pulmonary damage, AE significantly improved physical performance in CKD mice.

Intimal Hyperplasia and Arteriovenous Fistula Failure: Looking Beyond Size Differences

The development of venous intimal hyperplasia (IH) has been historically associated with failure of arteriovenous fistulas (AVF) used for hemodialysis. This long-standing assumption, based on histological observations, has been recently challenged by clinical studies indicating that the size of the intima by itself is not enough to explain stenosis or AVF maturation failure. Irrespective of this lack of association, IH is present in most native veins and fistulas, is prominent in many cases, and suggests a role in the vein that may not be reflected by its dimensions. Therefore, the contribution of IH to AVF dysfunction remains controversial. Using only clinical data and avoiding extrapolations from animal models, we critically discuss the biological significance of IH in vein remodeling, vascular access function, and the response of the venous wall to repeated trauma in hemodialysis patients. We address questions and pose new ones such as: What are the factors that contribute to IH in pre-access veins and AVFs? Do cellular phenotypes and composition of the intima influence AVF function? Are there protective roles of the venous intima? This review explores these possibilities, with hopes of rekindling a critical discussion about venous IH that goes beyond thickness and AVF outcomes.

Nocturnal blood pressure is associated with sympathetic nerve activity in patients with chronic kidney disease

Elevated nocturnal blood pressure (BP) and nocturnal non-dipping are frequently observed in patients with chronic kidney disease (CKD) and are stronger predictors of cardiovascular complications and CKD progression than standard office BP. The sympathetic nervous system (SNS) is thought to modulate diurnal hemodynamic changes and the vascular endothelium plays a fundamental role in BP regulation. We hypothesized that SNS overactivity and endothelial dysfunction in CKD are linked to elevated nocturnal BP and non-dipping. In 32 CKD patients with hypertension (56 ± 7 years), office BP, 24-hr ambulatory BP, muscle sympathetic nerve activity (MSNA) and endothelial function via flow-mediated dilation (FMD) were measured. Participants were subsequently divided into dippers (nighttime average BP > 10% lower than the daytime average BP, n = 8) and non-dippers (n = 24). Non-dippers had higher nighttime BP (p < .05), but not office and daytime BP, compared to dippers. MSNA burst incidence (81 ± 13 versus 67 ± 13 bursts/100 HR, p = .019) was higher and brachial artery FMD (1.7 ± 1.5 versus 4.7 ± 1.9%, p < .001) was lower in non-dippers compared to dippers. MSNA and FMD each predicted nighttime systolic (β = 0.48,-0.46, p = .02, 0.07, respectively) and diastolic BP (β = 0.38,-0.47, p = .04, 0.03, respectively) in multivariate-adjusted analyses. Our novel findings demonstrate that unfavorable nocturnal BP profiles are associated with elevated SNS activity and endothelial dysfunction in CKD. Specifically, CKD patients with higher nighttime BP and the non-dipping pattern have higher MSNA and lower FMD. These support our hypothesis that SNS overactivation and endothelial dysfunction are linked to the dysregulation of nighttime BP as well as the magnitude of BP lowering at nighttime in CKD.

Effects of aerobic exercise on vascular function in nondialysis chronic kidney disease: a randomized controlled trial

Endothelial dysfunction and arterial stiffness are nontraditional risk factors of chronic kidney disease (CKD)-related cardiovascular disease (CVD) that could be targeted with exercise. This study investigated the effect of moderate to vigorous aerobic exercise on vascular function in nondialysis CKD. In this randomized, controlled trial, 36 nondialysis patients with CKD (means ± SE, age: 58 ± 2 yr, estimated glomerular filtration rate: 44 ± 2 ml·min-1·1.73 m-2) were allocated to an exercise training (EXT) or control (CON) arm. The EXT group performed 3 × 45 min of supervised exercise per week at 60-85% heart rate reserve for 12 wk, whereas the CON group received routine care. Outcomes were assessed at 0 and 12 wk. The primary outcome, microvascular function, was assessed via cutaneous vasodilation during local heating measured by laser-Doppler flowmetry coupled with microdialysis. Participants were instrumented with two microdialysis fibers for the delivery of 1) Ringer solution and 2) the superoxide scavenger tempol. Conduit artery function was assessed via brachial artery flow-mediated dilation. Aortic pressure waveforms and pulse wave velocity were acquired with tonometry and oscillometry. Microvascular function improved after EXT (week 0 vs.week 12, EXT: 87 ± 2% vs. 91 ± 2% and CON: 86 ± 2% vs. 84 ± 3%, P = 0.03). At baseline, pharmacological delivery of tempol improved microvascular function (Ringer solution vs. tempol: 86 ± 1% vs. 90 ± 1%, P = 0.02) but was no longer effective after EXT (91 ± 2% vs. 87 ± 1%, P = 0.2), suggesting that an improved redox balance plays a role in EXT-related improvements. Brachial artery flow-mediated dilation was maintained after EXT (EXT: 2.6 ± 0.4% vs. 3.8 ± 0.8% and CON: 3.5 ± 0.6% vs. 2.3 ± 0.4%, P = 0.02). Central arterial hemodynamics and arterial stiffness were unchanged after EXT. Aerobic exercise improved microvascular function and maintained conduit artery function and should be considered as an adjunct therapy to reduce CVD risk in CKD.

Altered vascular function in chronic kidney disease: evidence from passive leg movement

Chronic kidney disease (CKD) is an independent risk factor for the development of cardiovascular disease and is characterized by reduced nitric oxide (NO) bioavailability and vascular dysfunction, typically assessed using brachial artery flow-mediated dilation (FMD). It has been previously reported that passive leg movement (PLM)-induced hyperemia, an assessment of lower extremity vascular function, is highly dependent on NO, but has not yet been utilized to assess vascular function in patients with CKD. The purpose of this study was to comprehensively assess vascular function in patients with CKD using PLM, in addition to the traditional FMD technique. Assessment of vascular function via PLM and FMD was performed on 12 patients (CKD, 66 ± 3 years) and 16 age-matched healthy controls (CON, 60 ± 2 years). Blood velocity and artery diameters during PLM and FMD were measured using duplex ultrasound of the femoral and brachial arteries, respectively. Habitual physical activity, assessed by accelerometry, was performed in a subset of each group. CKD patients had reduced peak leg blood flow (LBF) (384 ± 39 vs. 569 ± 77 mL/min, P < 0.05) and change in LBF from baseline to peak (∆peakLBF) (143 ± 22 vs. 249 ± 34 mL/min, P < 0.05) during PLM compared to CON. Additionally, PLM responses were significantly associated with kidney function and physical activity levels. As anticipated, FMD was significantly attenuated in CKD patients (5.2 ± 1.1 vs. 8.8 ± 1.2%, P < 0.05). In conclusion, both upper and lower extremity measures of vascular function indicate impairment in CKD patients when compared to controls. PLM appears to be a novel and feasible approach to assessing lower extremity vascular function in CKD.

There Is No Impact of Diabetes on the Endothelial Function of Chronic Kidney Disease Patients

BACKGROUND

Patients with chronic kidney disease (CKD) and type 2 diabetes mellitus (DM) have increased risk of endothelial dysfunction, cardiovascular disease, and mortality. Several studies have separately analyzed endothelial function in these populations. However, data of patients with both CKD and DM are scarce. The aim of this study was to evaluate whether the presence of DM has any additional effect on the endothelial dysfunction of CKD patients.

METHODS

We measured endothelial progenitor cells (EPCs), stromal-derived factor 1 alpha (SDF-1α), serum and urinary nitric oxide (NO), flow-mediated dilation (FMD), and pulse wave velocity (PWV) in 37 CKD patients with DM (CKD-DM group) and in 37 without DM (CKD group).

RESULTS

CKD-DM group had a higher prevalence of obesity (P < 0.01), previous myocardial infarction (P = 0.02), myocardial revascularization (P = 0.04), and a trend for more peripheral artery disease (P = 0.07). Additionally, CKD-DM group had higher EPC (P = 0.001) and PWV (P < 0.001) values. On the other hand, no difference in SDF-1α and serum or urinary NO and FMD was observed between the groups.

CONCLUSIONS

Endothelial dysfunction is frequent in CKD patients, and an additive effect of diabetes cannot be implicated, suggesting the predominant role of uremia in this condition.

Role of mitochondria-derived reactive oxygen species in microvascular dysfunction in chronic kidney disease

Cardiovascular disease is the leading cause of mortality in chronic kidney disease (CKD). Mitochondrial dysfunction secondary to CKD is a potential source of oxidative stress that may impair vascular function. This study sought to determine if mitochondria-derived reactive oxygen species contribute to microvascular dysfunction in stage 3-5 CKD. Cutaneous vasodilation in response to local heating was assessed in 20 CKD patients [60 ± 13 yr; estimated glomerular filtration rate (eGFR) 46 ± 13 ml·kg^-1·1.73 m^-2] and 11 matched healthy participants (58 ± 2 yr; eGFR >90 ml·kg^-1·1.73 m^-2). Participants were instrumented with two microdialysis fibers for the delivery of 1) Ringer solution, and 2) the mitochondria- specific superoxide scavenger MitoTempo. Skin blood flow was measured via laser Doppler flowmetry during standardized local heating (42°C). Cutaneous vascular conductance (CVC) was calculated as a percentage of the maximum conductance achieved with sodium nitroprusside infusion at 43°C. Urinary isofuran/F₂-isoprostane ratios were assessed by gas-chromatography mass spectroscopy. Isofuran-to-F₂-isoprostane ratios were increased in CKD patients (3.08 ± 0.32 vs. 1.69 ± 0.12 arbitrary units; P < 0.01) indicative of mitochondria-derived oxidative stress. Cutaneous vasodilation was impaired in CKD compared with healthy controls (87 ± 1 vs. 92 ± 1%CVC_max; P < 0.01). Infusion of MitoTempo significantly increased the plateau phase CVC in CKD patients (CKD Ringer vs. CKD MitoTempo: 87 ± 1 vs. 93 ± 1%CVC_max; P < 0.01) to similar levels observed in healthy controls ( P = 0.9). These data provide in vivo evidence that mitochondria-derived reactive oxygen species contribute to microvascular dysfunction in CKD and suggest that mitochondrial dysfunction may be a potential therapeutic target to improve CKD-related vascular dysfunction.

Effect of Febuxostat on the Endothelial Dysfunction in Hemodialysis Patients: A Randomized, Placebo-Controlled, Double-Blinded Study

BACKGROUND

Endothelial dysfunction is an important risk factor for cardiovascular diseases to occur in end-stage renal disease patients. Febuxostat, being a novel xanthine oxidase inhibitor, is apparently having a beneficial role in improving the endothelial dysfunction; however, data among hemodialysis patients are still limited.

METHODS

A prospective, placebo-controlled, block-randomized, double-blinded study was carried out to evaluate the effect of oral febuxostat on the endothelial dysfunction in hemodialysis patients. Fifty-seven eligible hemodialysis patients were randomly assigned to either the drug group (40 mg thrice weekly) or the placebo group. Serum Asymmetric dimethylarginine (ADMA), Serum uric acid (UA), and serum high sensitivity C-reactive protein (hsCRP) were measured at baseline and at the end of a 2-month study. Serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST), and the occurrence of pancytopenia were tested as safety parameters at baseline and at the end of study.

RESULTS

Serum UA significantly decreased from 7.5 ± 0.8 to 5.1 ± 1.2 mg/dL in the febuxostat group, while it did not change significantly in the placebo group. Treatment with febuxostat resulted in a significant decrease in the serum ADMA level from 1.027 ± 0.116 to 0.944 ± 0.104 µmol/L and the serum hsCRP level from 12.5 ± 1.65 to 12.1 ± 1.70 mg/L. Testing of serum ALT, serum AST, and pancytopenia revealed no significant difference in both groups.

CONCLUSION

Febuxostat appears to improve hyperuricemia and endothelial dysfunction and ameliorate inflammation in hemodialysis patients with no safety concerns.

Endothelial maintenance in health and disease: Importance of sex differences

The vascular endothelium has emerged as more than just an inert monolayer of cells lining the vascular bed. It represents the interface between the blood stream and vessel wall, and has a strategic role in regulating vascular homeostasis by the release of vasoactive substances. Endothelial dysfunction contributes to the development and progression of cardiovascular disease. Recognition of sex-specific factors implicated in endothelial cell biology is important for the identification of clinically relevant preventive and/or therapeutic strategies. This review aims to give an overview of the recent advances in understanding the importance of sex specific observations in endothelial maintenance, both in healthy and diseased conditions. The female endothelium is highlighted in the context of polycystic ovary syndrome and pre-eclampsia. Furthermore, sex differences are explored in chronic kidney disease, which is currently appreciated as one of public health priorities. Overall, this review endorses integration of sex analysis in experimental and patient-oriented research in the exciting field of vascular biology.

Long term evolution of endothelial function during kidney transplantation

Background

Endothelial dysfunction is an important precursor to the development of atherosclerosis, and has been suggested to play a role in the increased cardiovascular risk in patients with end stage renal disease. Endothelial function improves rapidly following post kidney transplantation, but the long term change remains unclear. Hypothesizing that endothelial function would remain improved long term post kidney transplantation, we evaluated the longitudinal change of endothelial function, measured by flow-mediated dilation (FMD) of the brachial artery, from months 1 to 24 post transplantation. Given the previously reported association of fibroblast growth factor 23 (FGF-23) with endothelial dysfunction, we also examined changes in the association between FGF-23 levels and the change in FMD following kidney transplantation.

Methods

We performed a prospective cohort study of 149 kidney transplant recipients, measuring endothelial function by FMD at months 1, 12, and 24 post-transplant. FGF-23 levels were measured at months 1 and 24 post-transplant. Linear mixed effects models were used to assess both the unadjusted and adjusted outcomes.

Results

The cohort (mean age 49 ± 13 years) was 74 % male and 75 % white. The median FMD was 6.3 % (IQR: 3.4, 10.2), 5.4 % (IQR: 3.1, 8.5), and 5.6 % (IQR: 3.5, 9.1) at 1, 12, and 24 months, respectively. After adjustment for covariates, compared to month 1, no change occurred in FMD at 12 months (−0.66 %; 95 % CI: −1.81 %, 0.49 %; P = 0.262) or 24 months (−0.25 %; 95%CI: −1.76 %, 1.26 %; P = 0.746). FGF-23 decreased significantly over time (P = 0.024), but there was no significant association between FGF-23 and FMD (P = 0.799).

Conclusion

Endothelial function remained stable at 12 and 24 months from 1 month post-kidney transplant, indicating that the improved endothelial function seen with transplant is maintained up to 2 years post transplantation. There was also no significant association between FGF-23 and endothelial function following kidney transplantation.

The Vascular Endothelium in Chronic Kidney Disease: A Novel Target for Aerobic Exercise

Endothelial dysfunction occurs in chronic kidney disease (CKD) and increases the risk for cardiovascular disease. The mechanisms of endothelial dysfunction seem to evolve throughout kidney disease progression, culminating in reduced L-arginine transport and impaired nitric oxide bioavailability in advanced disease. This review examines the hypothesis that aerobic exercise may reverse endothelial dysfunction by improving endothelial cell L-arginine uptake in CKD.

Effect of Moderate Aerobic Exercise Training on Endothelial Function and Arterial Stiffness in CKD Stages 3-4: A Randomized Controlled Trial

BACKGROUND

Evidence of a beneficial effect of exercise training on mediators of vascular disease is accumulating in chronic kidney disease (CKD), but its effect on vascular function in vivo still has to be established. The present study was designed to investigate whether a formal aerobic exercise training program improves peripheral endothelial function in patients with CKD stages 3 to 4.

STUDY DESIGN

Randomized controlled trial with a parallel-group design.

SETTING & PARTICIPANTS

48 patients with CKD stages 3 to 4 without established cardiovascular disease were randomly assigned to either an exercise training program or usual care. 40 patients completed the study (exercise training, 19; usual care, 21).

INTERVENTION

The 3-month home-based aerobic training program consisted of 4 daily cycling sessions of 10 minutes each at a target heart rate, calculated as 90% of the heart rate achieved at the anaerobic threshold. Patients in the usual-care group were given standard therapy.

OUTCOMES

The primary outcome was peripheral endothelial function. Secondary outcomes were aerobic capacity, arterial stiffness, numbers of endothelial (EPCs) and osteogenic progenitor cells (OPCs), migratory function of circulatory angiogenic cells, and health-related quality of life.

MEASUREMENTS

Endothelial function was assessed with flow-mediated dilation of the brachial artery, aerobic capacity by peak oxygen uptake (VO(2peak)), arterial stiffness by carotid-femoral pulse wave velocity, numbers of EPCs and OPCs by flow cytometry, circulatory angiogenic cell function by an in vitro migratory assay, and quality of life by the Kidney Disease Quality of Life-Short Form questionnaire.

RESULTS

Exercise training significantly improved VO(2peak) and quality of life, but not in vivo vascular function (flow-mediated dilation and carotid-femoral pulse wave velocity) or cellular markers for vascular function (EPC and OPC count and circulatory angiogenic cell migratory function).

LIMITATIONS

Short duration and intermittent nature of the exercise intervention.

CONCLUSIONS

In patients with CKD stages 3 to 4 without overt cardiovascular disease, 3 months of aerobic exercise training improved VO(2peak) and quality of life, without altering endothelial function or arterial stiffness.

Assessment of endothelial dysfunction in Asian Indian patients with chronic kidney disease and changes following renal transplantation

BACKGROUND

Endothelial dysfunction may explain increased cardiovascular risk in patients with chronic kidney disease (CKD).

METHODS

Brachial artery was imaged during reactive hyperemia (endothelium-dependent, flow-mediated dilatation, FMD) and during glyceryl trinitrate-mediated dilatation (nitroglycerine-mediated dilatation, NMD, endothelium-independent) in 108 patients with CKD and three months following renal transplantation (RT) in 60 of them.

RESULTS

Patients with CKD had significantly lower FMD vs. controls (9.1% vs. 18.3%, p < 0.001) while NMD was comparable (19.8% vs. 21.8%, p = ns). Impaired FMD (<4.5%) was observed in 26.8% patients with CKD and was more common in those on hemodialysis (HD; 28.4% vs. 15.4%) vs. those not on dialysis. FMD for patients with glomerular filtration rate (GFR) 15-60 vs. <15 mL/min/1.73 m(2) was 12.9% and 8.8% (p = 0.05; respectively -29% and -52% lower vs. controls), indicating reduced FMD with increasing CKD severity. There was +72% increase in FMD following RT (9.1 to 15.7%, p < 0.001) while mean NMD was unchanged. Following RT, only 3.3% had impaired FMD.

CONCLUSIONS

Patients with CKD have endothelial dysfunction as evidenced by reduced FMD. Decreased FMD indicating worsening endothelial function was noted with increasing severity of CKD. Within three months of RT, there was significant improvement in FMD, while NMD values did not change.

NADPH oxidase-derived reactive oxygen species contribute to impaired cutaneous microvascular function in chronic kidney disease

Oxidative stress promotes vascular dysfunction in chronic kidney disease (CKD). We utilized the cutaneous circulation to test the hypothesis that reactive oxygen species derived from NADPH oxidase and xanthine oxidase impair nitric oxide (NO)-dependent cutaneous vasodilation in CKD. Twenty subjects, 10 stage 3 and 4 patients with CKD (61 ± 4 yr; 5 men/5 women; eGFR: 39 ± 4 ml·min(-1)·1.73 m(-2)) and 10 healthy controls (55 ± 2 yr; 4 men/6 women; eGFR: >60 ml·min(-1)·1.73 m(-2)) were instrumented with 4 intradermal microdialysis fibers for the delivery of 1) Ringer solution (Control), 2) 10 μM tempol (scavenge superoxide), 3) 100 μM apocynin (NAD(P)H oxidase inhibition), and 4) 10 μM allopurinol (xanthine oxidase inhibition). Skin blood flow was measured via laser-Doppler flowmetry during standardized local heating (42°C). N(g)-nitro-l-arginine methyl ester (L-NAME; 10 mM) was infused to quantify the NO-dependent portion of the response. Cutaneous vascular conductance (CVC) was calculated as a percentage of the maximum CVC achieved during sodium nitroprusside infusion at 43°C. Cutaneous vasodilation was attenuated in patients with CKD (77 ± 3 vs. 88 ± 3%, P = 0.01), but augmented with tempol and apocynin (tempol: 88 ± 2 (P = 0.03), apocynin: 91 ± 2% (P = 0.001). The NO-dependent portion of the response was reduced in patients with CKD (41 ± 4 vs. 58 ± 2%, P = 0.04), but improved with tempol and apocynin (tempol: 58 ± 3 (P = 0.03), apocynin: 58 ± 4% (P = 0.03). Inhibition of xanthine oxidase did not alter cutaneous vasodilation in either group (P > 0.05). These data suggest that NAD(P)H oxidase is a source of reactive oxygen species and contributes to microvascular dysfunction in patients with CKD.

Endothelial Dysfunction in Patients With Coronary Artery Disease

Background:

The use of flow-mediated dilation (FMD) as a surrogate indicator for the extent of coronary artery disease (CAD) remains largely unknown. We assessed FMD at the brachial artery in 89 consecutive patients undergoing coronary angiography.

Methods and Results:

Patients were classified in groups 0 to 3 according to the number of diseased vessels and the SYNTAX score was calculated. The FMD decreased significantly from groups 0 to 3 ( P < .001). There was a significant linear relation between SYNTAX score and FMD (corrected r2 = .64, P < .001). In multivariate analysis, a reduced FMD was the only significant independent predictor of the presence of CAD (odds ratio [OR] 1.78, P = .032) and of CAD severity (OR 1.85, P = .005).

Conclusion:

This study confirms that FMD is reduced in patients with CAD and that such reduction in FMD is related to the extent of the disease. Therefore, FMD at the brachial artery is likely to represent a reliable indicator of CAD burden.

Post-dilution high convective transport improves microinflammation and endothelial dysfunction independently of the technique

BACKGROUND/AIMS

We examined the effects of different online hemodiafiltration techniques on microinflammation and endothelial damage/repair.

METHODS

The study was designed as a prospective crossover study. Flow cytometry was used to measure CD14(+)CD16(+) monocytes, apoptotic endothelial microparticles (EMPs), and endothelial progenitor cells (EPCs).

RESULTS

Patients treated with high-flux hemodialysis showed a marked chronic inflammatory state (HF-HD 11 ± 2) versus healthy subjects (HS 3.9 ± 2.3; p < 0.05). High convective transport, independent of the technique used, improves microinflammatory parameters (OL-HDF 7.3 ± 2.1 or MID 6.5 ± 3.4; p < 0.05) and the endothelial damage/repair balance compared to HF-HD (EPCs HF-HD 0.3 ± 0.2), with no differences found between the two modalities (EPCs OL-HDF 0.6 ± 0.1, MID 0.6 ± 0.2; p < 0.05).

CONCLUSION

An increase in convective transport improves the microinflammatory state and the endothelial damage/repair of these patients independently of the technique used.

Enhanced maternal origin of the 22q11.2 deletion in velocardiofacial and DiGeorge syndromes

Velocardiofacial and DiGeorge syndromes, also known as 22q11.2 deletion syndrome (22q11DS), are congenital-anomaly disorders caused by a de novo hemizygous 22q11.2 deletion mediated by meiotic nonallelic homologous recombination events between low-copy repeats, also known as segmental duplications. Although previous studies exist, each was of small size, and it remains to be determined whether there are parent-of-origin biases for the de novo 22q11.2 deletion. To address this question, we genotyped a total of 389 DNA samples from 22q11DS-affected families. A total of 219 (56%) individuals with 22q11DS had maternal origin and 170 (44%) had paternal origin of the de novo deletion, which represents a statistically significant bias for maternal origin (p = 0.0151). Combined with many smaller, previous studies, 465 (57%) individuals had maternal origin and 345 (43%) had paternal origin, amounting to a ratio of 1.35 or a 35% increase in maternal compared to paternal origin (p = 0.000028). Among 1,892 probands with the de novo 22q11.2 deletion, the average maternal age at time of conception was 29.5, and this is similar to data for the general population in individual countries. Of interest, the female recombination rate in the 22q11.2 region was about 1.6-1.7 times greater than that for males, suggesting that for this region in the genome, enhanced meiotic recombination rates, as well as other as-of-yet undefined 22q11.2-specific features, could be responsible for the observed excess in maternal origin.