Protective effect of N-acetylcysteine on early outcomes of deceased renal transplantation.

We investigated the effects of the antioxidant N-acetylcysteine (NAC) on early outcomes of deceased donor renal transplantation. Between April 2005 and June 2008, adult primary graft recipients of deceased renal donors were assigned to treatment (n = 38) or control (n = 36) groups and evaluated for 90 days and one year after renal transplantation. The treatment group received NAC orally (600 mg twice daily) from day 0 to 7 postoperatively. Renal function was determined by serum creatinine, MDRD and Cockcroft-Gault estimated GFR (eGFR), delayed graft function (DGF) and dialysis free Kaplan-Meier estimate curve. Serum levels of thiobarbituric acid reactive substances (TBARS), were employed as markers of oxidative stress. The NAC group displayed a lower mean serum creatinine during the first 90 days (P = .026) and at 1 year after transplantation (P = .005). Furthermore, the NAC group showed a higher mean eGFR throughout the first 90 days and at 1 year. DGF was lower among the NAC group (P = .017) and these recipients required fewer days of dialysis (P = .012). Oxidative stress was significantly attenuated with NAC (P < .001). Our results suggested that NAC enhanced early outcomes of deceased donor renal transplantation by attenuating oxidative stress.

Glomerular filtration is reduced by high tidal volume ventilation in an in vivo healthy rat model

Mechanical ventilation has been associated with organ failure in patients with acute respiratory distress syndrome. The present study examines the effects of tidal volume (V T) on renal function using two V T values (8 and 27 mL/kg) in anesthetized, paralyzed and mechanically ventilated male Wistar rats. Animals were randomized into two groups of 6 rats each: V T8 (V T, 8 mL/kg; 61.50 ± 0.92 breaths/min; positive end-expiratory pressure, 3.0 cmH2O; peak airway pressure (PAW), 11.8 ± 2.0 cmH2O), and V T27 (V T, 27 mL/kg; 33.60 ± 1.56 breaths/min; positive end-expiratory pressure, none, and PAW, 22.7 ± 4.0 cmH2O). Throughout the experiment, mean PAW remained comparable between the two groups (6.33 ± 0.21 vs 6.50 ± 0.22 cmH2O). For rats in the V T27 group, inulin clearance (mL·min-1·body weight-1) decreased acutely after 60 min of mechanical ventilation and even more significantly after 90 min, compared with baseline values (0.60 ± 0.05 and 0.45 ± 0.05 vs 0.95 ± 0.07; P < 0.001), although there were no differences between groups in mean arterial pressure or gasometric variables. In the V T8 group, inulin clearance at 120 min of mechanical ventilation remained unchanged in relation to baseline values (0.72 ± 0.03 vs 0.80 ± 0.05). The V T8 and V T27 groups did not differ in terms of serum thiobarbituric acid reactive substances (3.97 ± 0.27 vs 4.02 ± 0.45 nmol/mL) or endothelial nitric oxide synthase expression (94.25 ± 2.75 vs 96.25 ± 2.39 percent). Our results show that glomerular filtration is acutely affected by high tidal volume ventilation but do not provide information about the mechanism.

Glomerular filtration is reduced by high tidal volume ventilation in an in vivo healthy rat model.

Mechanical ventilation has been associated with organ failure in patients with acute respiratory distress syndrome. The present study examines the effects of tidal volume (V(T)) on renal function using two V T values (8 and 27 mL/kg) in anesthetized, paralyzed and mechanically ventilated male Wistar rats. Animals were randomized into two groups of 6 rats each: V (T)8 (V(T), 8 mL/kg; 61.50 +/- 0.92 breaths/min; positive end-expiratory pressure, 3.0 cmH(2)O; peak airway pressure (PAW), 11.8 +/- 2.0 cmH(2)O), and V T27 (V(T), 27 mL/kg; 33.60 +/- 1.56 breaths/min; positive end-expiratory pressure, none, and PAW, 22.7 +/- 4.0 cmH(2)O). Throughout the experiment, mean PAW remained comparable between the two groups (6.33 +/- 0.21 vs 6.50 +/- 0.22 cmH(2)O). For rats in the V(T)27 group, inulin clearance (mL.min(-1).body weight(-1)) decreased acutely after 60 min of mechanical ventilation and even more significantly after 90 min, compared with baseline values (0.60 +/- 0.05 and 0.45 +/- 0.05 vs 0.95 +/- 0.07; P < 0.001), although there were no differences between groups in mean arterial pressure or gasometric variables. In the V(T)8 group, inulin clearance at 120 min of mechanical ventilation remained unchanged in relation to baseline values (0.72 +/- 0.03 vs 0.80 +/- 0.05). The V(T)8 and V(T)27 groups did not differ in terms of serum thiobarbituric acid reactive substances (3.97 +/- 0.27 vs 4.02 +/- 0.45 nmol/mL) or endothelial nitric oxide synthase expression (94.25 +/- 2.75 vs 96.25 +/- 2.39%). Our results show that glomerular filtration is acutely affected by high tidal volume ventilation but do not provide information about the mechanism.

Kleine-Levin syndrome. Clinical course, polysomnography and multiple sleep latency test. Case report.

A case of Kleine-Levin syndrome, with chronic severe periodic hypersomnia is described in a 17-year-old female. The first episode started when she was 15 years old. The episodes were characterized by periodic hypersomnia accompanied by hyperphagia, lasting 5 days, and repeating at 28 to 60 day intervals. The severity of hypersomnia prevented her from attending school activities. Outside the hypersomnia periods, she was asymptomatic. EEG, brain computerized tomography and brain nuclear magnetic resonance were normal; all-night polysomnography, Multiple Sleep Latency Test (MSLT) and Epworth Sleepiness Scale (ESS) were within normal limits. During the period of hypersomnolence, polysomnography showed short sleep latency and short REM latency. MSLT mean sleep latency was 1.8 min; and REM period was present in one subtest; the ESS was markedly elevated.

Comparisons of models of cortical necrosis with segmental infarction.

Sodium and water excretion were studied by standard clearance techniques in three experimental models where renal mass was reduced by superficial cortical necrosis (CN) or ischemic segmental infarction (SI). During hydropenia either CN or SI were able to conserve and regulate sodium to a very similar degree. After expansion of extracellular volume, CN reabsorbed less sodium and water than SI. In free-water clearance (CH2O) experiments, the 'apparent distal' sodium delivery was higher in CN than in SI, suggesting a decreased sodium and water reabsorption in the proximal tubules of juxtamedullary nephrons (JM). Both kidneys had similar CH2O when factored for inulin clearance but when CH2O was corrected for 'apparent distal' sodium delivery it was lower in CN than in SI, demonstrating an incapacity of JM to dilute urine. CN also showed less capacity to reabsorb free water than SI. Thus, the use of CN and SI within the same animal was useful to study functional differences between superficial and juxtamedullary nephrons. The present study also suggests that the kidney with superficial CN was unable to perform maximal urine dilution and concentration.

Renal concentrating defect in protein malnutrition: the role of the thick ascending limb of Henle and inner medullary collecting duct.

The present study was carried out to examine the effect of chronic dietary protein restriction on renal water handling in the rat. During hypotonic saline infusion, the malnourished rats showed a lower free-water clearance, corrected by inulin clearance (7.2 +/- 0.4%), than normal rats (13.6 +/- 2.5%, p less than 0.051), although the fractional distal delivery of sodium did not differ from normal. Throughout hypertonic saline diuresis the free-water reabsorption (TcCH20) corrected by inulin clearance was lower in malnourished rats (6.62 +/- 0.64%) than in control animals (9.25 +/- 0.62, p less than 0.05). Moreover, when TcH20 was referred to the osmolar clearance, malnourished animals showed lower values than normal. These results suggest a defect in NaCl transport in the thick ascending limb of Henle. In vitro measurements of diffusional water permeability (PDW) in the inner medullary collecting duct (IMCD) obtained from malnourished rats showed an increase from 40.0 +/- 5.4 x 10(5) cm/s to 71.3 +/- 5.4 x 10(5) cm/s by adding maximum effective concentration (50 microU/ml) of arginine vasopressin (VP) to the bath. These values were not different from the PDW observed in the IMCD of normal rats. In another series of microperfusion experiments, the hydraulic conductivity in IMCD of malnourished rats measured also in the presence of maximum effective concentration of VP was 29.7 +/- 3.4 x 10(-6) cm/atm/s, a mean value not significantly different from that observed in the IMCD of normal rats (35.2 +/- 4.3 x 10(-6) cm/atm/s).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of protein restriction on the severity and recovery from ischemic renal failure.

The effects of chronic dietary protein restriction on ischemic renal failure were evaluated in rats subjected to 90 min of bilateral renal clamping. The rats were kept on either 20% casein (regular) diet or casein-free (protein-free) diet 10 days before and 21 days after renal injury. Rats on regular protein diet showed higher levels of BUN and serum creatinine and had a lower inulin clearance (microliter/min/100 g BW) than animals on protein-free diet (289 +/- 34 vs 582 +/- 103, p less than 0.05) 2 days after ischemia. However, the inulin clearance measured 21 days following ischemia was significantly higher in rats on regular diet (1468 +/- 181) than those maintained on protein-free diet after ischemia (560 +/- 167). When unilateral 90 min ischemia was performed in rats on regular diet, the postischemic kidneys showed an incomplete recovery of the inulin clearance (226 +/- 35) compared to the contralateral kidney (900 +/- 116), 21 days after ischemia; whereas in rats on a protein-free diet the inulin clearance averaged 106 +/- 17 in the postischemic kidney and 345 +/- 41 in the right kidney. When left renal ischemia and contralateral nephrectomy were performed, the inulin clearance was 1149 +/- 74 in rats on regular diet and 534 +/- 60 in rats on protein-free diet, 21 days following renal insult. These results suggest that protein restriction can play a protective role against renal ischemia in an initial phase, but it limits the late recovery from ischemia. The presence of a normal contralateral kidney inhibits the functional recovery of the postischemic kidney and a contralateral nephrectomy produces a compensatory functional hypertrophy of the postischemic kidney, even in rats on a protein-free diet.

Effect of potassium depletion on ischemic renal failure.

The present study was carried out to examine the effect of potassium depletion in rat kidneys subjected to a temporary ischemic event produced by clamping of left renal artery. The postischemic kidneys of rats on a normal diet with adequate potassium intake showed an increase in H2O, Na and K excretion, with no change in inulin clearance whereas significant differences were found in potassium-deprived rats. Potassium depletion was brought about by dietary K deprivation for 10 days. K-depleted rats (serum K = 2.5 +/- 0.1 mEq/l) had a decrease in inulin clearance of the postischemic kidney from 1.01 +/- 0.10 to 0.43 +/- 0.05 ml/min (p less than 0.01), and a greater increase in fractional excretion of H2O, Na and K when compared to normal rats. The postischemic kidney from both normal and hypokalemic rats showed a decrease in Na-K-ATPase of the inner stripe of the outer medulla. These data indicate that short-term ischemia produces polyuria, increases natriuresis and kaliuresis, associated, at least in part, with a decrease in Na-K-ATPase in the inner stripe of the outer medulla (probably the thick ascending limb of Henle) and that K depletion potentiates ischemic renal failure.

Renal concentration defect induced by cisplatin. The role of thick ascending limb and papillary collecting duct.

The effects of cisplatin (5 mg/kg BW given intraperitoneally) on renal concentration mechanism were evaluated initially by clearance studies in rats 5-7 days after cisplatin administration and compared to normal rats. During hypotonic saline infusion, cisplatin rats showed a lower inulin clearance (0.56 +/- 0.07 vs. 1.12 +/- 0.09 ml/min/100 g BW, p less than 0.01), a higher fractional distal delivery (CNa + CH2O/Cin) (36.3 +/- 4.4 vs. 22.8 +/- 4.5%, p less than 0.05), and lower CH2O/CNa + CH2O (33.6 +/- 5.8 vs. 56.5 +/- 5.0%, p less than 0.01). During hypertonic saline infusion the TcH2O/Cosm was lower in cisplatin (18.3 +/- 1.1%) than in normal rats (33.4 +/- 3.5%, p less than 0.01). These results suggest a defect in NaCl transport in the thick ascending limb of Henle and proximal tubule. In order to characterize these tubular defects, we measured Na-K-ATPase activity (microM Pi/mg protein/h). In the renal cortex of cisplatin rats the ATPase activity was lower (18.1 +/- 3.2) than in normal rats (33.4 +/- 6.4, p less than 0.05), also in the inner strip of the outer medulla of cisplatin rats Na-K-ATPase was reduced (26.0 +/- 5.7) when compared with normal rats (67.3 +/- 9.2, p less than 0.01), presumably representing a decrease in enzyme activity in the thick ascending limb.(ABSTRACT TRUNCATED AT 250 WORDS)

Efeito do furosemide e aminofilina na insuficiencia renal aguda pos-isquemica experimental. / Effects of furosemide and aminophylline in experimental post-ischemic acute renal failure

O efeito do furosemide e da aminofilina sobre a recuperacao da insuficiencia renal aguda foi estudado em ratos submetidos a isquemia renal por clampeamento da aorta,abaixo e acima da arteria renal esquerda, permanecendo o rim direito como controle. A administracao de altas doses de furosemide (100 mg/kg peso), antes de se proceder a isquemia renal,nao impediu a queda de filtracao glomerular e o efeito oligurico. O furosemide injetado em outros oito animais, apos a inducao da isquemia renal, nao alterou a taxa de filtracao glomerular (0,24 +/- 0,04 ml/min para 0,23 +/- 0,04 ml/min), produzindo apenas aumento da diurese e natriurese em seis dos animais estudados. A administracao de aminofilina, inibidor da adenosina, substancia vasoconstritora renal, cuja producao aumenta durante a isquemia renal, tambem nao aumentou a taxa de filtracao glomerular do rim pos-isquemico (0,09 +/- 0,04 ml/min para 0,10 +/- 0,02 ml/ min) e nem alterou a excrecao de agua e soluto. Estes dados permitem concluir que nem o furosemide e nem a aminofilina produzem uma recuperacao mais rapida da filtracao glomerular na insuficiencia renal aguda experimental e que apenas o furosemide pode transformar uma insuficiencia renal aguda oligurica em poliurica