Intradialytic Complement Activation Precedes the Development of Cardiovascular Events in Hemodialysis Patients.

Background: Hemodialysis (HD) is a life-saving treatment for patients with end stage renal disease. However, HD patients have markedly increased rates of cardiovascular morbidity and mortality. Previously, a link between the complement system and cardiovascular events (CV-events) has been reported. In HD, systemic complement activation occurs due to blood-to-membrane interaction. We hypothesize that HD-induced complement activation together with inflammation and thrombosis are involved in the development of CV-events in these patients. Methods: HD patients were followed for the occurrence of CV-events during a maximum follow-up of 45 months. Plasma samples were collected from 55 patients at different time points during one HD session prior to follow-up. Plasma levels of mannose-binding lectin, properdin and C3d/C3 ratios were assessed by ELISA. In addition, levels of von Willebrand factor, TNF-α and IL-6/IL-10 ratios were determined. An ex-vivo model of HD was used to assess the effect of complement inhibition. Results: During median follow-up of 32 months, 17 participants developed CV-events. In the CV-event group, the C3d/C3-ratio sharply increased 30 min after the start of the HD session, while in the event-free group the ratio did not increase. In accordance, HD patients that developed a CV-event also had a sustained higher IL-6/IL-10-ratio during the first 60 min of the HD session, followed by a greater rise in TNF-α levels and von Willebrand factor at the end of the session. In the ex-vivo HD model, we found that complement activation contributed to the induction of TNF-α levels, IL-6/IL-10-ratio and levels of von Willebrand factor. Conclusions: In conclusion, these findings suggest that early intradialytic complement activation predominantly occurred in HD patients who develop a CV-event during follow-up. In addition, in these patients complement activation was accompanied by a pro-inflammatory and pro-thrombotic response. Experimental complement inhibition revealed that this reaction is secondary to complement activation. Therefore, our data suggests that HD-induced complement, inflammation and coagulation are involved in the increased CV risk of HD patients.

Renal handling of galectin-3 in the general population, chronic heart failure, and hemodialysis.

BACKGROUND: Galectin-3 is a biomarker for prognostication and risk stratification of patients with heart failure (HF). It has been suggested that renal function strongly relates to galectin-3 levels. We aimed to describe galectin-3 renal handling in HF. METHODS AND RESULTS: In Sprague-Dawley rats, we infused galectin-3 and studied distribution and renal clearance. Furthermore, galectin-3 was measured in urine and plasma of healthy controls, HF patients and hemodialysis patients. To mimic the human situation, we measured galectin-3 before and after the artificial kidney. Infusion in rats resulted in a clear increase in plasma and urine galectin-3. Plasma galectin-3 in HF patients (n=101; mean age 64 years; 93% male) was significantly higher compared to control subjects (n=20; mean age 58 years; 75% male) (16.6 ng/mL versus 9.7 ng/mL, P<0.001), while urinary galectin-3 in HF patients was comparable (28.1 ng/mL versus 35.1 ng/mL, P=0.830). The calculated galectin-3 excretion rate was lower in HF patient (2.3 mL/min [1.5 to 3.4] versus 3.9 mL/min [2.3 to 6.4] in control subjects; P=0.005). This corresponded with a significantly lower fractional excretion of galectin-3 in HF patients (2.4% [1.7 to 3.7] versus 3.0% [1.9 to 5.5]; P=0.018). These differences, however, were no longer significant after correction for age, gender, diabetes, and smoking. HF patients who received diuretics (49%) showed significantly higher aldosterone and galectin-3 levels. Hemodialysis patients (n=105; mean age 63 years; 65% male), without urinary galectin-3 excretion, had strongly increased median plasma galectin-3 levels (70.6 ng/mL). CONCLUSIONS: In this small cross-sectional study, we report that urine levels of galectin-3 are not increased in HF patients, despite substantially increased plasma galectin-3 levels. The impaired renal handling of galectin-3 in patients with HF may explain the described relation between renal function and galectin-3 and may account for the elevated plasma galectin-3 in HF.

Na(+)-H+ exchange inhibition attenuates ischemic injury in rat random pattern skin flap: the role of mitochondrial ATP-sensitive potassium channels.

Necrosis of distal portion of skin flaps due to ischemia still remains a problem in plastic surgery. Following ischemia, a cascade of deleterious events including over-activity of Na(+)-H(+) Exchanger (NHE) takes place. In present study we evaluated the effect of the potent NHE inhibitor, 5-(N-ethyl-N-isopropyl) amiloride (EIPA) on ischemic tissue injury in a skin flap model, and investigated the role of mitochondrial ATP-sensitive K(+) channels (K(ATP)) in this phenomenon. Seventy-eight rats were randomly divided into thirteen treatment groups (6 rats each). Four groups received different doses of EIPA in the flap. EIPA/GLY group received an effective dose of a K(ATP) channel blocker, glibenclamide (GLY, 0.3mg/kg) intraperitoneally (i.p.) 30 min before raising the flap, and a local effective dose of EIPA (0.1mM) immediately after raising the flap. EIPA/diazoxide group (EIPA/DIA) received a sub-effective dose of diazoxide (7.5mg/kg i.p.) 30 min before raising the flap and a local sub-effective dose of EIPA (0.075 mM). EIPA 0.1 and 0.2mM significantly increased flap survival area compared to control group (56.01 ± 6.1%, P<0.001). The protective effect of EIPA (0.1mM) was abolished by administration of glibenclamide (0.3mg/kg i.p.). Co-administration of a sub-effective dose of EIPA (0.075 mM), with a sub-effective dose of diazoxide (7.5mg/kg i.p.) significantly improved flap survival (P<0.05). We demonstrated that the NHE inhibitor, EIPA can increase random pattern skin flap survival. Administration of diazoxide potentiates this effect, while glibenclamide abolishes that, implicating that the protective effect of EIPA is mediated through mitochondrial-K(ATP) channels.

Comparison of cardiac positron emission tomography perfusion defects during stress induced by hemodialysis versus adenosine.

The cardiac stress imposed by hemodialysis may differ from that induced by pharmacologic agents used for myocardial perfusion imaging-based stress testing. With repetitive intradialytic [(13)N]ammonia positron emission tomography, we showed that standard hemodialysis had an acute adverse effect on cardiac perfusion and left ventricular function that was not detected by standard diagnostic adenosine stress testing.

Protective effects of acute lithium preconditioning against renal ischemia/reperfusion injury in rat: role of nitric oxide and cyclooxygenase systems.

Delayed graft function secondary to ischemia/reperfusion injury has been shown to be associated with increased rate of allograft failure following kidney transplantation. Previously, we have shown that chronic lithium pretreatment protects kidney against ischemia/reperfusion injury. In the present study we aimed to examine the effects of acute lithium administration on the renal ischemia/reperfusion injury in rat. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60 min, two weeks after right nephrectomy. The mechanism of lithium-mediated renoprotection was explored by combined use of lithium and nitro-l-arginine methyl ester (L-NAME) (non-selective nitric oxide synthase inhibitor) and/or indomethacin (non-selective cyclooxygenase pathway inhibitor). Lithium-treated animals were given 40 mg/kg lithium chloride intraperitoneally, 30 min before ischemia. To investigate the role of nitric oxide and cyclooxygenase pathways in renoprotective effect of lithium, L-NAME and/or indomethacin were administered before lithium injection. Serum creatinine, blood urea nitrogen, and renal histology were assessed after 24h of reperfusion. Lithium preconditioning significantly reduced creatinine and blood urea nitrogen (P<0.001) and improved renal histology. Administration of L-NAME completely reversed renoprotective effect of lithium. In contrast indomethacin significantly potentiated the lithium renoprotection. Moreover, co-administration of L-NAME and indomethacin completely abolished the protective effects of lithium. The results show that a single dose of lithium significantly improves renal function following ischemia/reperfusion injury. In conclusion, the ability of lithium to enhance renal tissue tolerance against ischemia/reperfusion injury suggests a potential clinical application in the setting of kidney transplantation. However, more detailed investigations are required before any definite conclusion.

Chronic upregulation of the endogenous opioid system impairs the skin flap survival in rats.

Recent studies suggest a detrimental role for long-term opioid receptor stimulation in different tissues. In this study, we investigated the effect of chronic over production of endogenous opioids on skin tolerance to ischemia in a rat model of cholestasis. Sixty-six rats were randomly divided into 11 groups, 6 animals each. First group served as surgical control. In first experiment, 1, 2, and 3 weeks bile duct ligation (BDL) rats and SHAM-operated controls underwent random-pattern skin-flaps by elevating a caudally based dorsal flap (2 x 8 cm). BDL was performed by midline laparotomy and ligating the common bile duct under general anesthesia. Flap survival was assessed after 7 days (14-, 21-, and 28-day cholestatic rats, respectively). In another experiment, the first effective duration of BDL on flap survival (21 days) was chosen to receive either chronic (20 mg/kg/day) or acute (20 mg/kg, 30 minutes before flap surgery) intraperitoneal naltrexone (NTX). In the first experiment, flap survival was 56.6% +/- 2.6% (mean +/- SEM) in control group and 50.2% +/- 3.9%, 37.4% +/- 3.4%, and 35.4% +/- 6.9% in groups of 14-, 21-, and 28-day cholestatic rats, which were significantly impaired in 21- and 28-day group. In the second experiment, skin flap survival was completely reversed to their SHAM control level after chronic and acute NTX treatment (63.6% +/- 7.6% and 61.9% +/- 5.6% vs. 55.1% +/- 4.2% and 54.9% +/- 4.3%, respectively, P < 0.05). Chronic cholestasis (longer than 2 weeks) decreases the skin flap survival, which is reversed by systemic NTX. This study provides evidence, for the first time, that long-term elevated opioidergic tone impairs the skin tolerance to ischemia.

Sacrococcygeal pilonidal sinus treated by a new fascio-cutaneous flap.

PURPOSE: This study reported the technical details and preliminary clinical outcomes of a new fascio-cutaneous transposition flap for the surgical treatment of pilonidal sinus. METHODS: Fifty-two patients with pilonidal sinus were surgically treated. During the surgical procedure, an inferiorly pedicled, fascio-cutaneous flap with specific geometric characteristics was prepared and transposed. Postoperative pain, complications, duration of hospital stay, and time off worked were assessed. Patients were followed for eighteen months after surgery. RESULTS: The mean hospital stay was 2 days. Drains and sutures were removed after 3 and 12 days, respectively. No flap ischemia, wound dehiscence or major complications were observed. Tension on suture lines and pain after surgery were negligible. Wound infections occurred in 4 patients (7.7 percent) and were managed by removing a few sutures. Seroma was detected in 6 patients (11.5 percent). The mean time patients missed work was 7 days. No recurrence was observed during the follow-up period of 18 months. CONCLUSIONS: With no disease recurrence, minimal complication rate, time off work, and acceptable aesthetic outcome, this fascio-cutaneous transposition flap technique is a safe and effective method for surgically treating pilonidal sinus.