Are there sex differences in cardiovascular outcomes in non-dialysis CKD patients?

Background

Sex differences for cardiovascular (CV) risk and outcomes in chronic kidney disease (CKD) patients not on dialysis have been scarcely or never investigated. We therefore studied this important aspect in a cohort of CKD stage 2-5 in the south of Italy.

Methods

We tested the relationship between sex and fatal and non-fatal major CV events in a cohort of 759 stage 2-5 CKD patients followed up for a median time of 36 months.

Results

Out of 759 patients, 455 were males (60%) and the remaining 304 patients were females (40%). During the follow-up, 42 patients died, and 118 had fatal and non-fatal CV events. On univariate Cox regression analyses, the male sex failed to be associated with all-cause mortality but was strongly related to the incidence rate of fatal and non-fatal major CV events [hazard ratio (HR) 1.75, 95% confidence interval (CI) 1.18-2.60, P = .006]. Data adjustment for a series of major potential confounders did not materially affect the strength of this relationship (HR 1.78, 95% CI 1.03-3.09). Further analysis testing the effect of age on major CV outcomes by sex showed an effect modification by this risk factor on the same outcome (P = .037) because the HR of male versus female CV events increased progressively with aging.

Conclusion

Male patients in stage G2-5 CKD had a higher risk for CV events compared with female patients. Age was shown to be a risk modifier for the association between sex and CV events and this risk increased linearly across a wide age spectrum in CKD patients.

Home Pulse Pressure Predicts Death and Cardiovascular Events in Peritoneal Dialysis Patients

Increased arterial hypertension represents a prevalent condition in peritoneal dialysis patients that is often related to volume expansion. Pulse pressure is a robust predictor of mortality in dialysis patients, but its association with mortality is unknown in peritoneal patients. We investigated the relationship between home pulse pressure and survival in 140 PD patients. During a mean follow-up of 35 months, 62 patients died, and 66 experienced the combined event death/CV events. In a crude COX regression analysis, a five-unit increase in HPP was associated with a 17% increase in the hazard ratio of mortality (HR: 1.17, 95% CI 1.08-1.26 p < 0.001). This result was confirmed in a multiple Cox model adjusted for age, gender, diabetes, systolic arterial pressure, and dialysis adequacy (HR: 1.31, 95% CI 1.12-1.52, p = 0.001). Similar results were obtained considering the combined event death-CV events as an outcome. Home pulse pressure represents, in part, arterial stiffness, and it is strongly related to all-cause mortality in peritoneal patients. In these high cardiovascular risk populations, it is important to maintain optimal blood pressure control, but it is fundamental to consider all the other cardiovascular risk indicators, such as pulse pressure. Home pulse pressure measurement is easy and feasible and can add important information for the identification and management of high-risk patients.

MO802DOES ETELCALCETIDE REVERSE MYELOFIBROTIC BONE CHANGES DUE TO HYPERPARATHYROIDISM? A CASE REPORT

Background and Aims

A 21 year old boy with a diagnosis of Autosomal Recessive Polycystic Kidney Disease and Caroli disease reached a final stage of chronic kidney disease (CKD) and started haemodialysis.

Method

After 3 years in haemodialysis he underwent a kidney transplant from a cadaveric donor. His transplanted kidney worked fairly well until the patients was 31 year old when he developed graft dysfunction (serum creatinine from 2.7 to 5 mg/dL in a very short period). There was a concomitant increase in serum phosphate levels (8.3 mg/dl) and iPTH that progressively increased to 1032 pg/ml despite a traditional therapy.

Results

At age 32, the patient returned to haemodialysis treatment thrice weekly with a concomitant a progressive worsening of hyperparathyroidism with bone pain . Cinacalcet at a dosage of 30 mg daily treatment was initiated, then it was increased to 120 mg daily without any benefit. Two years later, being the clinical situation without any improvement and being the patient scarcely compliant to the therapy and because a further enlargement of parathyroid glands was observed, a Parathyroidectomy (PTX) was advised.

Nevertheless, PTX was not performed because of patient’s refusal. Furthermore, despite Erythropoietic Stimulating Agent (ESA) therapy, he developed severe anemia that required regular and frequent blood transfusions. iPTH increased to 4500 pg/ml [Fig.1] with a parallel rise in alkaline phosphatase &gt;600 UI/L [Fig.2]. A Computed Tomography scan showed multiple bone-thickening lesions. He thus initiated Etelcalcetide 5 mg e.v. 3 times a week, after the HD session but without any benefit. The dosage was then increased to 7.5 mg but the patient gradually became frail and developed pancytopenia and low-grade fever. Hematological evaluation with bone marrow biopsy was performed in December 2019. Bone marrow histology showed severe fibrosis [Myelofibrosis (MF) grade 3] with normal bone marrow cytogenetics. Blood samples for mutations in JAK-2, CALR, and MPL and BCR-ABL rearrangement were negative. There was no evidence for a myeloproliferative neoplasm (MPN) or metastatic lesions.

During the following months, while on a 7,5 mg dose of etalcalcetide, there was a gradual reduction in iPTH [Fig.1] and serum alkaline phosphatase [Fig.2], up to 500 pg/dl and 200 IU/L respectively. The patient developed asymptomatic, often severe, hypocalcemia which was managed with therapy.

The patient’s clinical conditions gradually improved, anemia responded to lower doses of ESAs. A bone marrow biopsy was repeated after one year (December 2020) and it showed a reduction in fibrosis (MF grade varying from 1-2). Then etelcalcetide dosage was reduced while serum calcium and phosphate levels were in the normal limit.

Conclusion

Myelofibrosis secondary to renal osteodystrophy is an uncommon complication. It has been rarely reported and usually is associated with primary hyperparathyroidism. Marrow fibrosis and pancytopenia is related to the excessive iPTH that upregulates production of cytokines and paracrine factors in the bone marrow (IL-1a, IL-6, FNF-a, TGF–b, and platelet-derived growth factor) and it has an important stimulatory effect on fibroblast proliferation. It is known that surgical parathyroidectomy is associated with a reduction of bone marrow fibrosis in primary hyperparathyroidism. To our knowledge, this is probably the first case of tertiary hyperparathyroidism in which the effect of etelcalcetide is comparable to parathyroidectomy as far as on calcium-phosphate balance, and a significant improvement in bone marrow fibrosis and hemoglobin. In conclusion, etelcalcetide at least in this patient seems as effective as PTX on bone balance, bone marrow and anemia.

MO706PATIENTS AND CENTER-RELATED FACTORS IN PERIOTONEAL CHOICE IN INCIDENT PATIENTS: A REGIONAL EXPERIENCE

Background and Aims

Effective outpatient organization is essential in the management of patients with chronic kidney disease. Although peritoneal dialysis (PD) has many advantages it is still not popular.

Method

The aim of this study was to evaluate patient and center-related factors that affect the final choice of peritoneal dialysis (PD) versus hemodialysis (HD) in the Calabrian region (Italy). We analyzed 2 annual regional surveys performed by nephrologists (2017 and 2018) in incident dialysis patients. Collected factors included: early and late referral to the dialysis program, pre-dialysis participation in outpatient visits, first dialysis access [peritoneal catheter (PC), central venous catheter (CVC), arteriovenous fistula (AVF)], final dialysis treatment (HD or PD) and the care giver.

Results

The study sample included 296 incident patients (63% males) aged 66±15 years. Time to referral influenced the type of first dialysis access. Among patients with early referral, 35% initiated dialysis by a PC, 34% by AVF and 31% by CVC, while among those with late referral, only 5% started dialysis by a PC, 15% by AVF, and the majority (80%) by CVC (P&lt;0.001). Time to referral was also associated with pre-dialysis visits (34%, 33% and 34% versus 5%, 22% and 73%, respectively, P&lt;0.001). When evaluating clinical suitability for treatment modality, 54% of early referrals and 45% of late referrals were eligible for PD. The choice of dialytic modality was again related to time to referral: 38% with early referral chose PD compared to 15% of those with late referral (P&lt;0.001). Furthermore, in patients who participated in the pre-dialysis program, 38% started PD versus 11% of patients that did not participate (P&lt;0.001). The role of the caregiver remains uncertain.

Conclusion

These data confirm that a more attentive and dedicated organization of the pre-dialysis outpatient program would contribute to a greater expansion of the peritoneal dialysis program.

MO109CHARACTERIZATION OF RESISTANT HYPERTENSION IN CKD PATIENTS

Background and Aims

Hypertension resistant to drug treatment is common among CKD patients. However, the phenotype of resistant hypertension in the CKD population is still loosely defined and scarcely characterized.

Method

In a cohort of 759 stage 2-5 CKD patients, we identified a subgroup of 647 patients with &gt;4 longitudinal visits (range 4-7 visits) over a median follow-up time of 36 months. These patients did not differ from the original study population as for age (62±11 years vs 62±11), gender (59% vs 60%), diabetes (34% vs 35%) and eGFR (36±13 versus 36±13 ml/min/1.73m2). We adopted a conservative definition of resistant hypertension i.e. as a BP above the 2020 KDIGO guideline threshold (130/80 mmHg) in spite of concurrent use of 3 antihypertensive agents (at maximum tolerated doses) of different classes including a diuretic or BP controlled with four or more medications in at least 75% of visits. Adherence to drug treatment in this cohort was systematically checked by attending physicians across all visits. Data are given as mean ± SD or as median and interquartile range (IQR).

Results

Across the 36 months follow-up, 131 out of 647 patients (20%) had resistant hypertension in &gt;75% of visits. Resistant hypertensive patients were older (64±8 years vs 61±11), more frequently diabetics (53% vs 29%) and with background cardiovascular comorbidities (38% vs 29%) , higher body mass index (BMI) (30±5 kg/m2 vs 28±4 kg/m2), serum phosphate (3.9±0.7 mg/dL vs 3.7±0.8 mg/dL), CRP (median: 3.2 mg/L, IQR: 1.6-6.5 vs 3.2 mg/L, IQR: 1.6-6.5 vs 2.1 mg/L, 0.9-5.1 mg/L), 24h urinary protein (median: 1.0 g/24h, IQR: 0.4-2.3 vs median: 0.5 g/24h, IQR: 0.2-1.0 g/24h) and lower serum albumin (4.1±0.5 g/dL vs 4.2±0.5 g/dL) and eGFR (34±13 ml/min/1.73m2 vs 37±14 ml/min/1.73m2 as compared to remaining patients (all P&lt;0.03). In a multiple logistic regression model, 24h proteinuria [odds ratio (OR): 1.31, 95% CI: 1.13-1.53, P&lt;0.001] and BMI [OR: 1.08, 95% CI: 1.03-1.13, P=0.001] resulted to be the first factors in rank explaining resistant hypertension followed by diabetes (OR: 1.83, 95% CI: 1.18-2.85, P=0.008). Age, background CV comorbidities, serum phosphate, serum CRP, albumin, and eGFR failed to be associated with resistant hypertension after multiple data adjustment (P ranging from: 0.14 to 0.61). Of note, the combination of 24h proteinuria, BMI and diabetes had a relevant discriminatory power for resistant hypertension because the area under the ROC curve area of these risk factors was 0.71 (95% CI: 0.66-0.76) (P&lt;0.001).

Conclusion

A rigorously defined phenotype of resistant hypertension has a 20% prevalence in the CKD population. Proteinuria, high BMI and obesity are the main risk factors associated with this phenotype. Optimization of diabetes control, weight loss and pharmacotherapy targeting proteinuria may mitigate resistant hypertension in the CKD population.

Reducing salt intake by urine chloride self-measurement in non-compliant patients with chronic kidney disease followed in nephrology clinics: a randomized trial

BACKGROUND

Adherence to low salt diets and control of hypertension remain unmet clinical needs in chronic kidney disease (CKD) patients.

METHODS

We performed a 6-month multicentre randomized trial in non-compliant patients with CKD followed in nephrology clinics testing the effect of self-measurement of urinary chloride (69 patients) as compared with standard care (69 patients) on two primary outcome measures, adherence to a low sodium (Na) diet (<100 mmol/day) as measured by 24-h urine Na (UNa) excretion and 24-h ambulatory blood pressure (ABPM) monitoring.

RESULTS

In the whole sample (N = 138), baseline UNa and 24-h ABPM were143 ± 64 mmol/24 h and 131 ± 18/72 ± 10 mmHg, respectively, and did not differ between the two study arms. Patients in the active arm of the trial used >80% of the chloride strips provided to them at the baseline visit and at follow-up visits. At the third month, UNa was 35 mmol/24 h (95% CI 10.8-58.8 mmol/24 h; P = 0.005) lower in the active arm than the control arm, whereas at 6 months the between-arms difference in UNa decreased and was no longer significant [23 mmol/24 h (95% CI -5.6-50.7); P = 0.11]. The 24-h ABPM changes as well as daytime and night-time BP changes at 3 and 6 months were similar in the two study arms (Month 3, P = 0.69-0.99; Month 6, P = 0.73-0.91). Office BP, the use of antihypertensive drugs, estimated Glomerular Filtration Rate (eGFR) and proteinuria remained unchanged across the trial.

CONCLUSIONS

The application of self-measurement of urinary chloride to guide adherence to a low salt diet had a modest effect on 24-h UNa and no significant effect on 24-h ABPM.

Sleep-Disordered Breathing and 24-Hour Ambulatory Blood Pressure Monitoring in Renal Transplant Patients: Longitudinal Study

Background Sleep-disordered breathing (SDB) is considered a strong risk factor for hypertension in the general population. This disturbance is common in end-stage kidney disease patients on long-term hemodialysis and improves early on after renal transplantation. Whether SDB may be a risk factor for hypertension in renal transplant patients is unclear. Methods and Results We investigated the long-term evolution of simultaneous polysomnographic and 24-hour ambulatory blood pressure (BP) monitoring recordings in a cohort of 221 renal transplant patients. Overall, 404 paired recordings were made over a median follow-up of 35 months. A longitudinal data analysis was performed by the mixed linear model. The apnea-hypopnea index increased from a median baseline value of 1.8 (interquartile range, 0.6-5.0) to a median final value of 3.6 (interquartile range, 1.7-10.4; P=0.009). Repeated categorical measurements of the apnea-hypopnea index were directly associated with simultaneous 24-hour, daytime, and nighttime systolic ambulatory BP monitoring (adjusted analyses; P ranging from 0.002-0.01). In a sensitivity analysis restricted to 139 patients with at least 2 visits, 24-hour, daytime, and nighttime systolic BP significantly increased across visits (P<0.05) in patients with worsening SDB (n=40), whereas the same BP metrics did not change in patients (n=99) with stable apnea-hypopnea index. Conclusions In renal transplant patients, worsening SDB associates with a parallel increase in average 24-hour, daytime, and nighttime systolic BP. These data are compatible with the hypothesis that the link between SDB and hypertension is causal in nature. Clinical trials are, however, needed to definitively test this hypothesis.

P0831HIGH SERUM ALKALINE PHOSPHATASE PREDICTS THE RISK OF CKD PROGRESSION: EFFECT NODIFICATION BY THE GFR

Background and Aims

In the post-hoc analyses of the SUSTAIN and ASSURE trials (Kidney Blood Press Res. 2018;43:449-457), Apabetalone, an epigenetic modulator which lowers serum alkaline phosphatase (AlkPhos), stabilized the GFR in patients with cardiovascular disease and a GFR &lt;60/ml/min/1.73m2. Analyzing the relationship between AlkPhos and renal outcomes in patients with established CKD is useful to preliminarily explore the biological hypothesis that AlkPhos is implicated in CKD progression.

Method

We investigated the relationship between AlkPhos and the risk for a combined renal end-point (30% GFR loss or dialysis/renal transplantation) in a cohort of 609 stage 3-5 CKD patients with an average GFR of 34.8±12.1ml/min/1.73 m2.

Results

Median AlkPhos levels were 91 IU/L (Interquartile range 71-117 IU/L) and in the vast majority of patients had values below 147 IU/L (the upper limit of the normal range). Over a median follow up of 3 years, two-hundred patients had the combined renal end-point. In an unadjusted analysis 1 ln increase in AlkPhos entailed a 49% risk excess for the renal end-point (HR: 1.49, 95% CI 1.11-2.01, P=0.008). Adjusting for traditional (age, gender, smoking, diabetes, total cholesterol, BMI, systolic BP, CV comorbidities) and CKD specific risk factors (hemoglobin, albumin, phosphate, and hs-CRP) did not modify the strength of this association (HR:1.48, 95% CI 1.08-2.02, P=0.016). Furthermore, In a fully adjusted analysis testing the GFR as an effect modifier of the AlkPhos - combined renal end point relationship showed a strong GFR- AlkPhos interaction (Figure). Indeed the risk for the combined renal end-point was gradually more pronounced at progressively more severe degrees of renal dysfunction, the HR being 0.94 (CI95% 0.60-1.47) at a GFR of 40 ml/min/m2 and 2.71 (CI95% 1.49-4.93) at 10 ml/min/1.73m2.

Conclusion

In patients with stage 3-5 CKD alkaline phosphatase within the normal range is associated with the risk for progression to ESRD and the GFR is an effect modifier of this relationship. Findings in this study are compatible with the hypothesis that within the normal range of this biomarker, the risk for CKD progression by alkaline phosphatase is amplified by the severity of CKD. These data are in keeping with post-hoc analyses of the SUSTAIN and ASSURE trials and provide circumstantial support to the hypothesis that interventions lowering serum alkaline phosphatase may mitigate CKD progression.

P0824QUALITY OF LIFE (QOL) DURING THE COURSE OF CKD: A LONGITUDINAL STUDY

Background and Aims

Measuring QoL in CKD patients is fundamental to estimate the human cost of chronic diseases and to assess the effect of treatments. Non-medical factors play an important role in CKD progression and QoL. However, there is very limited information on the evolution of QoL over time in CKD patients and it remains unclear whether traditional and CKD specific risk factors are implicated QoL in CKD patients over CKD progression.

Method

We studied a cohort of 582 stage 2-5 CKD patients (age: 61±12 years; M: 60%, diabetics: 33%) and measured QoL by the short form of the Rand corporation questionnaire (SF36), an instrument which measures eight domains of QoL (physical functioning, role physical health, energy fatigue, pain, role emotional problem, emotional well-being, social function, and general health] and two summary scores, (the physical component score and the mental component score) which are calculated by a well validated algorithm (Taft C et al, 2001, Quality of life research). In all patients the SF36 was administered at enrolment and after one (489 patients), two (n=434) and three (n=287) years. The evolution of SF36 dimensions over-time and the predictors of SF36 changes were analyzed by the Linear Mixed Model (LMM).

Results

At baseline the median value of the Physical Component Score (PCS) was 43.7 (Interquartile range: 34.0-50.3) and the Mental Component Score (MCS) was 46.3 (37-52.9) and on average did not change over the 3 years follow up [median PCS at the 3rd year: . 46.3 (35.7-52.0), median MCS at the 3rd year 43 (33.6-50.6)]. On average the GFR at baseline was 36±13 ml/min/1.73 m2 and declined to 34±17 ml/min/1.73m2 at the 3rd year. On detailed longitudinal analysis by the LMM the PCS associated with the evolution of the GFR over time (beta=0.10; 95% CI from 0.06 to 0.13; P&lt;0.001). Adjustment for time (0,1,2,3 years), age and gender did not materially modify such an association (beta=0.09; 95%CI from 0.06 to 0.13, p&lt;0.001) while further adjustment for traditional (Systolic BP, diabetes, smoking, cholesterol), BMI, CV comorbidities and CKD specific (hemoglobin, albumin, calcium, phosphate) risk factors attenuated but did not cancel out the PCS-GFR link (beta=0.05, 95%CI 0.006 to 0.093, P=0.03). This finding suggests that the PCS-GFR link is either largely confounded or mediated by these risk factors but that the same risk factors do not explain in full the same link . The MCS – GFR association was weaker (beta=0.05, 95%CI from 0.008 to 0.09; P=0.02) than the PCS-GFR relationship, became non significant after simple adjustment for time, age and gender (beta=0.04 ; 95%CI -0.003 to 0.08; P=0.07) and was nullified after full adjustment (beta=-0.01; 95%CI -0.07 to 0.04; P=0.59) for the same risk factors.

Conclusion

The PCS and the MCS remain stable over the course of CKD but appear associated with the evolution of the GFR over time. Traditional and CKD specific risk factors substantially confound and/ or mediate these associations.

Urine chloride self-measurement to monitor sodium chloride intake in patients with chronic kidney disease

Background Excessive sodium intake is a risk factor for hypertension, cardiovascular disease and the risk for kidney failure in chronic kidney disease (CKD) patients. Methods We tested the diagnostic performance and the feasibility of an inexpensive method based on urine chloride strips for self-monitoring sodium intake in a series of 72 CKD patients. Results Twenty-four hour urinary chloride as measured by the reactive strips and 24 h urinary sodium were interrelated (r=0.59, p<0.001). Forty-nine out of 72 patients (78%) had a 24 h urinary sodium >100 mmol/24 h, i.e. the upper limit recommended by current CKD guidelines. The strip method had 75.5% sensitivity and 82.6% specificity to correctly classify patients with urine sodium >100 mmol/24 h. The positive and the negative predictive values were 90.2% and 61.3%, respectively. The overall accuracy (ROC curve analysis) of urine chloride self-measurement for the >100 mmol/24 h sodium threshold was 87% (95% CI: 77%-97%). The large majority of patients (97%) perceived the test as useful to help compliance with the prescribed dietary sodium and considered the test as simple and of immediate application (58%) or feasible but requiring attention (39%). Conclusions A simple and inexpensive test for urine chloride measurement has a fairly good performance for the diagnosis of excessive sodium intake. The test is feasible and it is perceived by CKD patients as helpful for enhancing compliance to the dietary sodium recommendations. The usefulness of this test for improving hypertension control in CKD patients will be tested in a clinical trial (Clinicaltrials.gov RF-2010-2314890).

Pruritus and quality of life in renal transplant patients

BACKGROUND

Pruritus has a negative impact on quality of life (QoL) in dialysis patients. The reversibility of this symptom after renal transplantation and its impact upon QoL has scarcely been studied in these patients.

METHODS

Pruritus was evaluated by the Visual Analogue Scale (VAS), the Visual Rating Scale (VRS), and the Numerical Rating Scale (NRS) in 133 unselected renal transplant patients, 62 healthy subjects, and 29 hemodialysis patients. QoL was assessed by KDQOL-SF^™ 1.3. The reversibility of pruritus was studied by applying retrospectively the VRS.

RESULTS

The prevalence of pruritus by the VRS was 62% in hemodialysis patients, 32% in renal transplant patients, and 11% in healthy subjects (P<.001). The prevalence of pruritus among transplant patients was 32% by VRS and 38% by VAS and NRS. The prevalence of pretransplantation pruritus (68%) by the VRS recall questionnaire was higher than the prevalence of pruritus in the same patients after renal transplantation (32%, P<.01). Pruritus in transplant patients was associated with important dimensions of QoL, including social, emotional, and working limitations (P<.05 for the three comparisons).

CONCLUSIONS

The prevalence of pruritus markedly reduces after renal transplantation but remains substantially higher than in the general population and impacts upon quality of life in these patients.

[Obesity and chronic kidney disease]

In the last century, life expectancy in the economically developed countries has significantly increased. In parallel there has been an increase in the prevalence of obesity and of chronic kidney disease. Abdominal obesity is a relevant risk factor for death and cardiovascular complications in chronic kidney disease and in dialysis patients as well.

Sleep disordered breathing in renal transplant patients

Sleep disordered breathing (SDB) is a prevalent, important nontraditional cardiovascular (CV) risk factor in end-stage renal disease patients. The prevalence of SDB in renal transplant patients is unknown. We compared polysomnographic studies in 163 transplant patients with matched samples in the general population and explored longitudinally the effect of return to dialysis after graft failure on SDB in three consecutive cases. Episodes of nocturnal hypoxemia, average and minimal O(2) saturation overnight in transplant patients did not differ from those in individuals in the general population matched for age, gender and body mass index (BMI). The prevalence of moderate-to-severe SBD in these patients did not exceed the estimated prevalence of the same disturbance in the general population. The respiratory disturbance index in transplant patients was directly associated with BMI (p < 0.001). In the longitudinal study all indicators of SDB coherently increased after transplant failure. The prevalence of SDB in transplant patients does not differ from that in well-matched individuals in the general population. The favorable effect of renal transplantation on CV risk may be at least partially explained by the lack of risk excess for SDB in this population. Longitudinal observations after transplant failure are compatible with the hypothesis that renal transplantation reverses SDB.

The enzymatic machinery for ADMA synthesis and degradation is fully expressed in human adipocytes

BACKGROUND

The endogenous inhibitor of nitric oxide synthase (NOS), asymmetric dimethylarginine (ADMA), is implicated in endothelial dysfunction and is a marker of renal disease progression and cardiovascular (CV) complications. Various cell species exhibit the enzymatic system that generates and degrades this methylarginine, but it is unknown whether this machinery is expressed in adipocytes. The question is relevant because adipocyte-derived mediators are implicated both in renal and cardiovascular diseases.

METHODS

We measured ADMA concentration in pure adipocytes in culture and measured mRNA levels of the enzymes involved in ADMA metabolism (real-time polymerase chain reaction) both in pure adipocytes in culture and in adipose tissue harvested in 9 healthy subjects. These enzymes included protein arginine N-methyltransferases type I (PRMTs) involved in ADMA synthesis, dimethylarginine dimethylaminohydrolases (DDAHs) responsible for ADMA degradation and constitutive and inducible forms of NOS (i.e., NOS1, NOS2A and NOS3 genes), the main functional target of ADMA.

RESULTS

Human adipocytes express the whole gene set that codes for the enzymatic system responsible for the biosynthesis and the degradation of ADMA, and this methylarginine is actually released by adipocytes in culture. NOS gene isoforms have a low level of expression in human adipose tissue, indicating that putative functions of ADMA in fat cells may be in part mediated by mechanisms other than NOS inhibition.

CONCLUSIONS

Human adipocytes produce ADMA and express the full enzymatic machinery responsible for ADMA metabolism. Studying the functional implication of these findings may be of relevance for clarifying the role of fat mass expansion in human disease.

Human adipose tissue binds and metabolizes the endocannabinoids anandamide and 2-arachidonoylglycerol

Endocannabinoids are a group of biologically active endogenous lipids that have recently emerged as important mediators in energy balance control. The two best studied endocannabinoids, anandamide (N-arachidonoylethanolamine, AEA) and 2-arachidonoylglycerol (2-AG) are the endogenous ligands of the central and peripheral cannabinoid receptors. Furthermore, AEA binds to the transient receptor potential vanilloid type-1 (TRPV1), a capsaicin-sensitive, non-selective cation channel. The synthesis of these endocannabinoids is catalyzed by the N-acylphosphatidylethanolamine-selective phospholipase D (NAPE-PLD) and the sn-1-selective diacylglycerol lipase (DAGL), whereas their degradation is accomplished by the fatty acid amide hydrolase (FAAH) and the monoglyceride lipase (MGL), respectively. We investigated the presence of a functional endocannabinoid system in human adipose tissue from seven healthy subjects. Subcutaneous abdominal adipose tissue underwent biochemical and molecular biology analyses, aimed at testing the expression of this system and its functional activity. AEA and 2-AG levels were detected and quantified by HPLC. Real time PCR analyzed the expression of the endocannabinoid system and immunofluorescence assays showed the distribution of its components in the adipose tissue. Furthermore, binding assay for the cannabinoid and vanilloid receptors and activity assay for each metabolic enzyme of the endocannabinoid system gave clear evidence of a fully operating system. The data presented herein show for the first time that the human adipose tissue is able to bind AEA and 2-AG and that it is endowed with the biochemical machinery to metabolize endocannabinoids.

Prognostic value of 24-hour ambulatory blood pressure monitoring and of night/day ratio in nondiabetic, cardiovascular events-free hemodialysis patients

BACKGROUND

The use of 24-hour ambulatory blood pressure monitoring is increasing in end-stage renal disease (ESRD) patients but the prediction power for cardiovascular complications of time-averaged ambulatory blood pressure components has been little investigated in these patients.

METHODS

We analyzed the prognostic power of 24-hour ambulatory blood pressure monitoring for all-cause and cardiovascular mortality in 168 nondiabetic, events-free hemodialysis patients selected from a total dialysis population of about 450 patients.

RESULTS

During the follow-up period (38 +/- 22 months), 48 patients died, 29 of them of cardiovascular causes. On univariate Cox regression analyses, the night/day systolic ratio resulted to be the sole blood pressure indicator to be associated with all-cause and cardiovascular mortality while left ventricular hypertrophy (LVH) was a strong predictor of these outcomes. In multivariable Cox models not including LVH, the night/day systolic ratio maintained an independent prognostic value for incident outcomes. However, when both risk factors, LVH and night/day systolic ratio, were introduced into Cox models, LVH was no longer a significant predictor while the night/day systolic ratio became a predictor of marginal statistical significance.

CONCLUSION

The night/day ratio emerges as the sole ambulatory blood pressure monitoring-derived indicator providing significant prognostic information in patients with ESRD. However, this indicator as well as LVH loses substantial prediction power in statistical models including both risk factors. The results suggest that the night/day systolic ratio and LVH provide overlapping prognostic information, a phenomenon in keeping with the hypothesis that they represent a common pathway leading to adverse outcomes in ESRD.