The Effect of Magnesium Supplementation on Vascular Calcification in CKD: A Randomized Clinical Trial (MAGiCAL-CKD).

SIGNIFICANCE STATEMENT: Magnesium prevents vascular calcification in animals with CKD. In addition, lower serum magnesium is associated with higher risk of cardiovascular events in CKD. In a randomized, double-blinded, placebo-controlled trial, the authors investigated the effects of magnesium supplementation versus placebo on vascular calcification in patients with predialysis CKD. Despite significant increases in plasma magnesium among study participants who received magnesium compared with those who received placebo, magnesium supplementation did not slow the progression of vascular calcification in study participants. In addition, the findings showed a higher incidence of serious adverse events in the group treated with magnesium. Magnesium supplementation alone was not sufficient to delay progression of vascular calcification, and other therapeutic strategies might be necessary to reduce the risk of cardiovascular disease in CKD. BACKGROUND: Elevated levels of serum magnesium are associated with lower risk of cardiovascular events in patients with CKD. Magnesium also prevents vascular calcification in animal models of CKD. METHODS: To investigate whether oral magnesium supplementation would slow the progression of vascular calcification in CKD, we conducted a randomized, double-blinded, placebo-controlled, parallel-group, clinical trial. We enrolled 148 subjects with an eGFR between 15 and 45 ml/min and randomly assigned them to receive oral magnesium hydroxide 15 mmol twice daily or matching placebo for 12 months. The primary end point was the between-groups difference in coronary artery calcification (CAC) score after 12 months adjusted for baseline CAC score, age, and diabetes mellitus. RESULTS: A total of 75 subjects received magnesium and 73 received placebo. Median eGFR was 25 ml/min at baseline, and median baseline CAC scores were 413 and 274 in the magnesium and placebo groups, respectively. Despite plasma magnesium increasing significantly during the trial in the magnesium group, the baseline-adjusted CAC scores did not differ significantly between the two groups after 12 months. Prespecified subgroup analyses according to CAC>0 at baseline, diabetes mellitus, or tertiles of serum calcification propensity did not significantly alter the main results. Among subjects who experienced gastrointestinal adverse effects, 35 were in the group receiving magnesium treatment versus nine in the placebo group. Five deaths and six cardiovascular events occurred in the magnesium group compared with two deaths and no cardiovascular events in the placebo group. CONCLUSIONS: Magnesium supplementation for 12 months did not slow the progression of vascular calcification in CKD, despite a significant increase in plasma magnesium. CLINICAL TRIALS REGISTRATION: www.clinicaltrials.gov ( NCT02542319 ).

Effect of lymph leakage on renal allograft outcome from living donors.

Lymph leakage is a cause of prolonged fluid discharge in renal transplant patients. Lymph leakage during early post-transplantation is responsible for extracting immune substances; therefore, it may play a role in prognosis of the transplanted kidney. In this study, we aimed to investigate the effects of lymph leakage on different factors that play significant roles in renal allograft outcome. During the present case-control study, we evaluated 62 renal allograft recipients in which 31 subjects were complicated with lymph leakage and enrolled as the study group. The other 31 subjects were included in the control group who did not experience any lymph leakage during their post-transplantation period. All kidneys were transplanted from living donors. We investigated and compared the renal allograft rejection rate, hospitalization duration, serum urea, creatinine (Cr) and cyclosporine (CsA) levels, antithymoglobin (ATG) administration and treatment duration between the study and the control groups. There were no significant difference in the urea and Cr levels between the two groups (P >0.05). Early (one week) and late (one month) serum CsA levels of the study group were significantly higher than in the control group (P = 0.005 and P = 0.006). The number of days in which ATG receivers responded to therapy was significantly lower for the control group (P = 0.008). 21.93% of the study group subjects experienced allograft rejection, while this rejection probability was 28.38% for the control group (P = 0.799). Lymph leakage has no prominent role in renal function, which is estimated by Cr and urea levels in patients' serum during the days after transplantation. CsA level was higher in patients with lymph leakage, and all cases of allograft rejection were in the subjects with lymph leakage.

Remnant kidney function and size in living unrelated kidney donors after nephrectomy.

There are few published reports examining the extended outcome of donors after nephrectomy. The aim of present prospective study was to evaluate the changes of glomerular filtration rate (GFR) and ultrasonographic kidney size in unrelated living kidney donors during post-nephrectomy period. Thirty nine unrelated living kidney donors were prospectively followed after nephrectomy. Length, anterioposterior (AP) diameter, and cortical thickness of the kidney were determined before, one week and three months after nephrectomy. GFR and serum creatinine (Cr) level were assessed simultaneously. The mean age of participants was 25.41 +/- 2.67 years with the male to female ratio of 29 to 10. Although GFR decreased 1 week after nephrectomy (P= 0.001), considering the pre-nephrectomy GFR as a result of both kidneys' function and half of its value as a marker of the remnant kidney's function [(123.68 +/- 17.99)/2], the calculated GFR for the remnant kidney increased about 63% after one week and 91%, after three months of nephrectomy (P= 0.003). Remnant kidney length, AP diameter, and cortical thickness were significantly increased during post-nephrectomy follow up (P< 0.001, P< 0.001, and P= 0.001, respectively). Results of present study showed that the GFR of remnant kidney was increased after nephrectomy, and serum Cr level was not changed, despite the mild increase at first post nephrectomy week. Also, remnant kidney size increased following nephrectomy in donors.

Neuroprotective effects of erythropoietin during deep hypothermic circulatory arrest.

OBJECTIVE: Permanent mild-to-severe brain injury with neurologic sequelae remains a significant source of postoperative morbidity in cardiovascular surgery. There is increasing evidence that erythropoietin confers neuroprotective effects in various conditions of neuronal damage, such as hypoxia and cerebral ischaemia. Using a surviving porcine model, this study evaluates whether systemic treatment with erythropoietin induces brain protection in deep hypothermic circulatory arrest (DHCA). METHODS: Sixteen pigs (42+/-3 kg) randomly assigned into two groups (n=8) were subjected to 60 min of DHCA at an intracerebral temperature of 20 degrees C. The animals of the erythropietin group were treated perioperatively with 500 IU kg(-1) of recombinant human erythropoietin on 3 consecutive days beginning the day before surgery. Intracerebral monitoring was performed by subcortical microdialysis, brain tissue oxygenation, measurement of brain temperature and intracranial pressure. Neurologic recovery was evaluated daily. Perioperative S100 beta protein serum level was determined. The brains were harvested on the postoperative day 6 after perfusion fixation. Multiple brain regions were investigated histologically for hypoxic-ischaemic damage. RESULTS: The subcortical brain microdialysis detected significant increase of glycerol and lactate concentrations in both groups (P=0.0001) with considerably higher concentrations in the brain of control animals (P=0.011). There were no significant differences in neurological outcome (P=0.15). Erythropoietin-treated animals tended to a more complete and rapid neurological recovery. By contrast, none of the animals in the control group achieved complete neurological recovery. S100 beta protein as a putative marker of cerebral injury tended to be higher in the control group. Brain infarction was detectable in all control animals but only in two erythropoietin-treated animals. CONCLUSION: These results suggest some beneficial neuroprotective effects of erythropoietin in this model of global brain ischaemia induced by 1h of hypothermic circulatory arrest.

Postnephrectomy changes in Doppler indexes of remnant kidney in unrelated kidney donors.

INTRODUCTION: We aimed to evaluate the intralobar renal arteries indexes using the Doppler ultrasonography indexes, which have become the established method of kidney monitoring, in living unrelated kidney donors during the postnephrectomy period. MATERIALS AND METHODS: In this prospective study, we evaluated and followed up 34 living unrelated kidney donors. The Doppler ultrasonography indexes, including resistive index, pulsatility index, and peak systolic velocity, along with the grey-scale ultrasonographic indexes of cortical thickness, length, and anteroposterior diameter of the kidney were determined before nephrectomy, and then, 1 week and 3 months after nephrectomy. In addition, glomerular filtration rate were assessed simultaneously. RESULTS: The resistive index and pulsatility index did not change 1 week and 3 months after nephrectomy (P = .66 and P = .38, respectively). The peak systolic velocity at 1 week was significantly higher than its prenephrectomy value (P = .02). Also, the peak systolic velocity at 3 months was significantly higher than that prior to nephrectomy (P < .001). Indexes of the kidney size all increased during the follow-up period. The estimated glomerular filtration rate increased decreased 1 week after nephrectomy, but it reach to a level comparable with its preoperative values after 3 months. CONCLUSION: Results of the present study showed an increased peak systolic velocity in association with unaltered resistive index and pulsatility index in the remnant kidney of donors, during the short-term follow-up. This finding indicates the increased blood flow and kidney size in the remnant kidney of donors, following nephrectomy.

Different impact of normo- and hypotensive brain death on renal macro- and microperfusion--an experimental evaluation in a porcine model.

BACKGROUND: Despite the growing use of kidneys from living donors, organs harvested from brain dead donors are the dominant graft types used in renal transplantation. It is accepted that brain death (BD) has a damaging effect on the renal allograft, with a lower graft survival. Amongst various causes, changes in renal microperfusion could be responsible. Renocortical microperfusion was assessed during BD using thermal diffusion in a porcine model. METHODS: Two types of BD were induced in two groups of pigs [hypotension (Hypo-BD): n = 11; normotension (Normo-BD): n = 10] and compared to controls (n = 5) over a period of 210 min. We analysed systemic parameters [heart rate (HR), mean arterial blood pressure (MAP)], aortic blood flow (ABF) and renal perfusion [renal artery blood flow (RABF) and renocortical blood flow (RCBF)]. RESULTS: Following the two distinct forms of BD induction, a stable normo- or hypotension was observed. Haemodynamic parameters were only slightly changed (control group: MAP, 62+/-2 mmHg; HR, 95+/-3/min; Normo-BD: MAP, 56+/-4 mmHg; HR, 104+/-8/min; Hypo-BD: MAP, 43+/-3 mmHg; HR, 112+/-7/min). Solely dependent on systemic haemodynamics, RABF and RCBF decreased in the Hypo-BD (RABF: 142+/-19 to 94+/-9 ml/100 g/min; RCBF: 80+/-4 to 52+/-2 ml/100 g/min), while in Normo-BD group RABF mildly changed (158+/-13 ml/100 g/min) and RCBF decreased slightly from 76+/-3 to 70+/-6 ml/100 g/min. As opposed to the Normo-BD group, animals with Hypo-BD showed a significant decrease in RABF (reduction of 34%) and RCBF (reduction of 35%) with a sharp drop of MAP (reduction of 25%), however ABF remained relatively constant. CONCLUSIONS: In this model, a reduction of renocortical microperfusion in brain dead pigs was only found during haemodynamic instability (hypotension) and could not be attributed to BD as such. Our findings would support intensive cardiocirculatory stabilization for potential BD donors in order to minimize kidney preservation damage.

Effects of hemodynamic instability on brain death-induced prepreservation liver damage.

BACKGROUND: Brain death (BD) is an important multifactorial variable contributing to donor-specific liver damage. Our study aimed at assessing the specific effects of hemodynamic instability on systemic and hepatic parameters of perfusion, bowel ischemia, and oxidative stress in a porcine model of BD. METHODS: BD was induced in 16 pigs (German Landrace, 18-28 kg) in two groups (hypotension-BD [HYPO-BD], n=8; normotension-BD [NORM-BD], n=8), which were compared with control animals/living donors (n=6) for a period of 2 hr. We analyzed systemic hemodynamic parameters, bowel ischemia (intramucosal pH in the stomach and colon, plasma endotoxin levels, and endotoxin-neutralizing capacity [ENC]), and oxidative stress (total glutathione levels in erythrocytes) and compared the findings with hepatic parameters of perfusion (hepatic arterial flow, portal venous flow, and microperfusion) and liver oxidative stress (reduced glutathione and oxidized glutathione levels in the liver). RESULTS: Independent of the hemodynamic stability, liver macrocirculation and microcirculation decreased (HYPO-BD, 79+/-6 to 69+/-10 mL/100 g/min; NORM-BD, 81+/-10 to 73+/-7 mL/100 g/min; P<0.05). Hepatocellular damage (aspartate aminotransferase: NORM-BD, 49+/-20 units/L; HYPO-BD, 170+/-140 units/L; P<0.01) and hepatic oxidative stress (reduced glutathione in the liver/oxidized glutathione in the liver: NORM-BD, 29.4+/-2.3 to 13.0+/-1.3; HYPO-BD, 29.4+/-2.3 to 9.05+/-0.81; P<0.001) increased in both BD groups. With dependence on systemic hemodynamic parameters, bowel ischemia increased (intramucosal pH in the colon, 7.22+/-0.01, P<0.01; ENC, 75+/-14 endotoxin-neutralizing units/mL, P<0.01; endotoxin levels, 7+/-2 to 43+/-10 pg/mL, P<0.01) in the HYPO-BD group but not in the NORM-BD group or the living donor group. Furthermore, systemic oxidative stress was increased in the HYPO-BD group only (total glutathione levels in erythrocytes, 2.65+/-0.25 to 0.15+/-0.25 mM; P<0.01). CONCLUSIONS: During BD, liver-specific parameters (portal venous flow, microperfusion, aspartate aminotransferase activity, ENC, and hepatic oxidative stress) were compromised, independent of the hemodynamic status. Therefore, the systemic hemodynamic status does not reflect the functional status of the liver during BD.