Evidence-based renal protection in cardiac surgery

Effect of pentoxifylline on the testicular hemodynamic, volume, testosterone, nitric oxide levels and semen quality in Ossimi rams during non breeding-season

During the non-breeding season, Ossimi rams have testicular regression, including reductions in blood flow, size and spermatogenesis. The objective was to determine the effect of pentoxifylline (PTX) on Ossimi rams during the non-breeding season. Fifteen sexually mature Ossimi rams were allotted to three groups: (1) G0 (n = 5) control group (basic diet, no PTX); (2) G1 (n = 5) 10 mg/kg BW PTX; and (3) G2 (n = 5) 20 mg/kg BW PTX. The PTX was given orally once daily for 7 weeks (wk1 to wk7), whereas ultrasonographic assessment of testes, and collection of semen and blood started 1 week before PTX and were done weekly for 8 weeks (wk0 to wk7). In G2, there was a decrease(P < 0.05) in both Doppler indices (resistive index, pulsatility index) in G2 from wk2 to wk4 and an increase(P < 0.05) in ultrasonographic testicular coloration from wk2 to wk7. Moreover, G2 had the highest (P < 0.05) testicular volume (wk5 to wk7), individual motility, sperm viability and acrosome integrity (wk4 to wk7) and sperm cell concentration (wk6 and wk7). Blood concentrations of testosterone and nitric oxide were increased (P < 0.05) concurrent with decreased Doppler indices. In conclusion, PTX enhanced testicular blood flow and volume, semen quality, and concentrations of testosterone and nitric oxide potential in Ossimi rams during the non-breeding season, with potential to ameliorate deleterious effects of heat stress and perhaps enhance ram fertility.

Treatment of Patients with Cardiac Surgery Associated-Acute Kidney Injury

Members of the Acute Dialysis Quality Initiative (ADQI) participated in a 3-day conference in Vicenza in May 2007 to evaluate the available literature on this topic and draft consensus recommendations for research studies in this area. This report summarizes the available evidence and describes the key questions that will need to be addressed with the goal of standardizing the care of patients with cardiac surgery-associated acute kidney injury (CSA-AKI) and improving outcomes.

Effects of N-acetylcysteine and pentoxifylline on remote lung injury in a rat model of hind-limb ischemia/reperfusion injury

OBJECTIVE

To investigate the effects of N-acetylcysteine (NAC) and pentoxifylline in a model of remote organ injury after hind-limb ischemia/reperfusion (I/R) in rats, the lungs being the remote organ system.

METHODS

Thirty-five male Wistar rats were assigned to one of five conditions (n = 7/group), as follows: sham operation (control group); hind-limb ischemia, induced by clamping the left femoral artery, for 2 h, followed by 24 h of reperfusion (I/R group); and hind-limb ischemia, as above, followed by intraperitoneal injection (prior to reperfusion) of 150 mg/kg of NAC (I/R+NAC group), 40 mg/kg of pentoxifylline (I/R+PTX group), or both (I/R+NAC+PTX group). At the end of the trial, lung tissues were removed for histological analysis and assessment of oxidative stress.

RESULTS

In comparison with the rats in the other groups, those in the I/R group showed lower superoxide dismutase activity and glutathione levels, together with higher malondialdehyde levels and lung injury scores (p < 0.05 for all). Interstitial inflammatory cell infiltration of the lungs was also markedly greater in the I/R group than in the other groups. In addition, I/R group rats showed various signs of interstitial edema and hemorrhage. In the I/R+NAC, I/R+PTX, and I/R+NAC+PTX groups, superoxide dismutase activity, glutathione levels, malondialdehyde levels, and lung injury scores were preserved (p < 0.05 for all). The differences between the administration of NAC or pentoxifylline alone and the administration of the two together were not significant for any of those parameters (p > 0.05 for all).

CONCLUSIONS

Our results suggest that NAC and pentoxifylline both protect lung tissue from the effects of skeletal muscle I/R. However, their combined use does not appear to increase the level of that protection.

Protection of Pentoxifylline against Testis Injury Induced by Intermittent Hypobaric Hypoxia

To investigate the effect of pentoxifylline (PTX) on spermatogenesis dysfunction induced by intermittent hypobaric hypoxia (IHH) and unveil the underlying mechanism, experimental animals were assigned to Control, IHH+Vehicle, and IHH+PTX groups and exposed to 4 cycles of 96 h of hypobaric hypoxia followed by 96 h of normobaric normoxia for 32 days. PTX was administered for 32 days. Blood and tissue samples were collected 7 days thereafter. Serum malondialdehyde levels were used to assess lipid peroxidation; ferric-reducing antioxidant power (FRAP), superoxide dismutase, and catalase and glutathione peroxidase enzyme activities were assessed to determine antioxidant capacity in various samples. Testis histopathology was assessed after hematoxylin-eosin staining by Johnsen's testicular scoring system. Meanwhile, testosterone synthase and vimentin amounts were assessed by immunohistochemistry. Sperm count, motility, and density were assessed to determine epididymal sperm quality. IHH treatment induced significant pathological changes in testicular tissue and enhanced serum lipid peroxide levels, while reducing serum FRAP, antioxidant enzyme activities, and testosterone synthase expression. Moreover, IHH impaired epididymal sperm quality and vimentin structure in Sertoli cells. Oral administration of PTX improved the pathological changes in the testis. IHH may impair spermatogenesis function of testicular tissues by inducing oxidative stress, but this impairment could be attenuated by administration of PTX.

The Genetic Determinants of Renal Impairment Following Cardiac Surgery

Cardiac surgery is frequently performed, and acute renal dysfunction is a common adverse event following this procedure. Cardiac surgery-related renal injury independently predicts longer hospital stays and greater rates of morbidity and mortality. Although much work has been completed toward better understanding of this phenomenon, the state of knowledge concerning surgery-related renal injury remains limited. Currently, there is no effective paradigm to identify patients who are at risk for this condition; the specific mechanisms of renal injury during surgery are incompletely understood; and few therapies exist to prevent or treat this phenomenon. To better understand this common clinical problem, recent research has focused on the importance of genetic variability within the physiological and patho-physiological systems that underlie renal dysfunction following cardiac surgery. Emphasizing the importance of using genetics to elucidate molecular mechanisms of this disease, this article reviews the current literature on genetic polymorphisms and post cardiac surgery-related renal dysfunction.

Beneficial effect of pentoxifylline into the testis of rats in an experimental model of unilateral hindlimb ischemia/reperfusion injury

Objective

The objective of the present study was to investigate the role of pentoxifylline (PTX) on remote testicular injury caused by unilateral hind limb ischemia/reperfusion of rats.

Materials and Methods

Twenty healthy male Wistar rats were allocated randomly into two groups: ischemia/reperfusion (IR group) and ischemia/reperfusion + pentoxifylline (IR+PTX group). Ischemia was induced by placement of a rubber tourniquet at the greater trochanter for 2h. Rats in IR+PTX group received PTX (40 mg/kg IP) before the reperfusion period. At 24h after reperfusion, testes were removed and levels of superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT) and myeloperoxidase (MPO) activity were determined in testicular tissues. Three rats of each group were used for wet/ dry weight ratio measurement. Testicular tissues were also examined histopathologically under light microscopy.

Results

Activities of SOD and CAT in testicular tissues were decreased by ischemia/ reperfusion (P<0.05). Significantly increased MDA levels in testicular tissues were decreased by PTX treatment (P<0.05). MPO activity in testicular tissues in the IR group was significantly higher than in the IR+PTX group (P<0.05). The wet/dry weight ratio of testicular tissues in the IR group was significantly higher than in the IR+PTX group (P<0.05). Histopathologically, there was a statistically significant difference between two groups (P<0.05).

Conclusions

According to histological and biochemical findings, we conclude that PTX has preventive effects in the testicular injury induced by hind limb ischemia/reperfusion.

Acute Kidney Injury in Cardiac Surgery and Cardiac Intensive Care

Acute kidney injury (AKI) is a serious postoperative complication following cardiac surgery. Despite the incidence of AKI requiring temporary renal replacement therapy being low, it is nonetheless associated with high morbidity and mortality. Therefore, preventing AKI associated with cardiac surgery can dramatically improve outcomes in these patients. The pathogenesis of AKI is multifactorial and many attempts to prevent or treat renal injury have been met with limited success. In this article, we will discuss the incidence and risk factors for cardiac surgery associated AKI, including the pathophysiology, potential biomarkers of injury, and treatment modalities.

Evaluation of cystatin C with iohexol clearance in cardiac surgery

BACKGROUND

Post-operative renal dysfunction after cardiac surgery is not uncommon and can lead to adverse outcome. The ability to accurately monitor renal function is therefore important. Cystatin C is known to be a sensitive marker of the glomerular filtration rate (GFR), but it has not been fully evaluated in cardiac surgery. Iohexol clearance is considered a reliable reference method for the determination of GFR. The aim of this study is to, for the first time, evaluate the diagnostic accuracy of plasma cystatin C compared with iohexol clearance in cardiac surgery.

METHODS

Twenty-one patients scheduled for elective coronary artery bypass grafting were prospectively enrolled in the study. Before surgery and on the second post-operative day, an iohexol clearance was performed. Plasma cystatin C, plasma creatinine and plasma C-reactive protein were determined before surgery and on the first, second, third and fifth post-operative day. Estimated creatinine and cystatin C clearances were determined.

RESULTS

Post-operative cystatin C and 1/cystatin C correlated strongly to iohexol clearance (r=-0.90 and 0.86) and so did creatinine and 1/creatinine (r=-0.83 and 0.78). Estimated creatinine clearance differed from iohexol clearance (P<0.01), whereas estimated cystatin C clearance did not differ from iohexol clearance (P=0.81). No correlation was found between C-reactive protein and cystatin C.

CONCLUSION

This study indicates that clearance estimations based on cystatin C are more accurate compared with estimations based on creatinine in determining GFR in cardiac surgery. Cystatin C has, in this study population, a stronger correlation to iohexol clearance than creatinine.

The effect of hemodilution during normothermic cardiac surgery on renal physiology and function: a review

Although the definitions of renal dysfunction vary, loss of renal function is a common complication following cardiac surgery using cardiopulmonary bypass (CPB). When postoperative dialysis is required, mortality is approximately 50%. CPB-accompanied hemodilution is a major contributing factor to renal damage as it notably reduces oxygen delivery by reducing the oxygen transport capacity of the blood as well as disturbing the microcirculation. To minimize hypoxemic damage during CPB, lowering of body temperature is applied to reduce the patient’s metabolic rate. At present, however, temperature management during elective adult cardiac surgery is shifting from moderate hypothermia to normothermia. To determine whether the currently accepted levels of hemodilution during CPB can suffice the normothermic patient’s high oxygen demand, we focused this study on renal physiology and postoperative renal function. Hemodilution reduces the capillary density through a diminished capillary viscosity, thereby, redistributing blood from the renal medulla to the renal cortex. As the physiology of the renal medulla makes it a hypoxic environment, this part of the kidney appears to be especially at risk for hypoxic damage caused by a hemodilution-induced lowered oxygen transport and oxygen delivery. In addition, hemodilution is also likely to disturb the hormonal systems regulating renal blood distribution. Clinical studies, mostly of retrospective or observational nature, show that perioperative nadir hematocrit levels lower than approximately 24% are associated with an increased risk to develop postoperative renal failure. A better comprehension of the cause-and-effect relation between low perioperative hematocrits and loss of postoperative renal function may enable more effective renal protective strategies.

Emerging concepts in acute kidney injury following cardiac surgery

Acute kidney injury (AKI) remains a significant cause of morbidity and mortality following cardiac surgery. Through a more thorough understanding of perioperative genomics and the evolving role of early biomarkers of AKI, the authors seek to improve meaningful outcomes among cardiac surgery patients. In this review, the focus will be on advances in risk stratification, evolving definitions and improving early diagnosis of AKI, identification of effective individualized therapies, and future directions.

The effects of pentoxifylline into the kidneys of rats in a model of unilateral hindlimb ischemia/reperfusion injury

PURPOSE: To study the role of pentoxifylline (PTX) on remote kidney injury caused by muscle ischemia of left hindlimb of rats. METHODS: After xylazine and ketamine anesthesia, the left hindlimb of rats (n=66) were submitted to 6 hours ischemia (clamping the left common iliac artery). Three groups were used: sham group (SG, n=6), early group (EG, n=30) with reperfusion after 4 hours and late group (LG, n=30) with reperfusion after 24 hours. The saline solution (EG1, n=10 and LG1, n=10) or PTX (40mg.Kg-1) was administered in the reperfusion beginning (EG2, n=10/LG2, n=10) or divided in two doses in the ischemia beginning and reperfusion beginning (EG3, n=10/LG3, n=10). The plasmatic creatinokinase, urea, creatinine, sodium and potassium values were measure and histological samples from left kidney were prepared and H&E stained for scored cellular necrosis and degeneration of kidney tubules and thickness glomerulus determination. The apoptosis index was determined by immunohistochemical expression of the caspase-3. The tests of Mann-Whitney and Kruskal-Wallis (p < 0.05) were applied. RESULTS: The urea (90.5 ± 30.96 mg.dL-1), creatinine (2.28 ± 0.54 mg.dL-1), potassium (16 ± 3.66 mmol.dL-1) and mesangium thickness (0.97 ± 0.42 µm) values were significantly higher in group LG3. There was no significantly difference of caspase 3 expression between EG2 (16.35 ± 1.65%) and LG3 (15.57 ± 2.54%), and both were significantly worse than SG (9.8 ± 1.98%). CONCLUSIONS: The PTX has some protecting effect on remote kidney injury due to hindlimb ischemia/reperfusion injury only in the early phase of reperfusion.