Challenge to Predict Mobilized Peripheral Blood Stem Cells on the Fourth Day of Granulocyte Colony-Stimulating Factor Treatment in Healthy Donors: Predictive Value of Basal CD34+ Cell and Platelet Counts.

A longitudinal, prospective, observational, single-center cohort study on healthy donors was designed to identify predictors of CD34+ cell mobilization on day 4 after granulocyte colony-stimulating factor (G-CSF) administration. As potential predictors of mobilization, age, sex, body weight, height, blood volume, WBC count, peripheral blood (PB) mononuclear cell count, platelet (Plt) count, and hematocrit and hemoglobin levels were considered. Two different evaluations of CD34+ cell counts were determined for each donor: baseline (before G-CSF administration) and in PB on day 4 after G-CSF administration. One hundred twenty-two consecutive healthy donors with a median age of 47.5 years were enrolled. The median value of CD34+ on day 4 was 43 cells/µL (interquartile range, 23 to 68), and 81.1% of donors had ≥20 cells/µL. Basal WBC count, Plt count, and CD34+ were significantly higher for the subjects with CD34+ levels over median values on day 4. A multivariate quartile regression analysis, adjusted by sex, age, basal CD34+, and basal Plt count, showed a progressively stronger relationship between baseline CD34+ and Plt levels and the CD34+ levels on day 4. The basal CD34+ cut-off level to predict the levels of CD34+ on day 4 was either ≤2 cells/µL or ≥3 cells/µL and that of basal Plt count was ≤229 × 109/L or ≥230 × 109/L, respectively, to determine whether mobilization therapy should or should not be attempted. PB stem cell mobilization with G-CSF was highly effective on day 4, and herein we describe a model for predicting the probability of performing PB stem cell collection after a short course of G-CSF.

Long-term blood pressure monitoring by office and 24-h ambulatory blood pressure in renal transplant patients: a longitudinal study.

BACKGROUND: Renal transplant patients have a high prevalence of nocturnal hypertension, and hypertension misclassification by office blood pressure (BP) is quite common in these patients. The potential impact of hypertension misclassification by office BP on hypertension management in this population has never been analysed. METHODS: We performed a longitudinal study in a cohort of 260 clinically stable renal transplant patients. In all, 785 paired office and 24-h ambulatory blood pressure monitoring (24-hABPM) measurements over a median follow-up of 3.9 years were available in the whole cohort. RESULTS: A total of 74% of patients had nocturnal hypertension (>120/70 mmHg). Average office BP and 24-hABPM remained quite stable over follow-up, as did the prevalence of nocturnal hypertension, which was 77% at the last observation. However, the global agreement between office BP and average 24 h, daytime and night-time BP was unsatisfactory (k-statistics 0.10-0.26). In 193 visits (25% of all visits) where office BP indicated the need of antihypertensive therapy institution or modification (BP >140/90 mmHg), 24-hABPM was actually normal (<130/80 mmHg), while in 94 visits (12%), 24-hABPM was in the hypertensive range while office BP was normal. Overall, in 37% of visits, office BP provided misleading therapeutic indications. CONCLUSIONS: Hypertension misclassification by office BP is a common phenomenon in stable renal transplant patients on long-term follow-up. Office BP may lead to inappropriate therapeutic decisions in over one-third of follow-up visits in these patients.

A genetic marker of uric acid level, carotid atherosclerosis, and arterial stiffness: a family-based study.

BACKGROUND: Hyperuricemia associates with atherosclerosis complications, but it is uncertain whether this relationship is causal in nature. The urate transporter GLUT9 (encoded by the SLC2A9 gene) is a major genetic determinant of serum uric acid level in humans. Because polymorphisms are distributed randomly at mating (Mendelian randomization), studies based on GLUT9 polymorphisms may provide unconfounded assessment of the nature of the link between uric acid and atherosclerosis. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: Family-based study including 449 individuals in 107 families in a genetically homogeneous population in Southern Italy. FACTOR: Serum uric acid level, rs734553 allele, and age. OUTCOME: Ultrasound biomarkers of atherosclerosis (intima-media thickness [IMT] and internal diameter) and pulse wave velocity (PWV). RESULTS: Serum uric acid level was dose-dependently associated with the T allele of rs734553, a polymorphism in SLC2A9 (P=8×10(-6)). Serum uric acid level was a strong modifier of the relationship between age and IMT in fully adjusted analyses (ß=0.33; P=0.01), whereas no such relationship was found for internal diameter (ß=-0.15; P=0.3) or PWV (ß=0.10; P=0.6). The T allele coherently associated with carotid IMT, internal diameter, and PWV and emerged as an even stronger modifier of the age-IMT and age-internal diameter relationships in both crude and fully adjusted (ß=0.40 [P<0.001] and ß=0.48 [P=0.003], respectively) analyses. LIMITATIONS: This is a hypothesis-generating study. CONCLUSIONS: Results in this family-based study implicate uric acid as an important modifier of the age-dependent risk for atherosclerosis. Trials testing uric acid-lowering interventions are needed to prove this hypothesis.

Long-Term Changes in Sleep Disordered Breathing in Renal Transplant Patients: Relevance of the BMI.

Sleep disordered breathing (SDB), as defined by the Apnea Hypopnea Index (AHI), is a highly prevalent disturbance in end stage kidney disease. SDB improves early on after renal transplantation but long-term changes in AHI in these patients have not been studied. We studied the long-term changes in AHI in a series of 221 renal transplant patients (mean age: 47 ± 12 years; 70% males) over a median follow up of 35 months. Data analysis was made by the generalized estimating equations method (GEE). On longitudinal observation, the median AHI rose from 1.8 (Interquartile range: 0.6-5.0) to 2.9 (IQR: 1.0-6.6) and to 3.6 (IQR: 1.7-10.4) at the second and third visit, respectively (p = 0.009 by the GEE model and the proportion of patients with moderate to severe SDB rose from 8% to 20%. Longitudinal changes in minimum oxygen saturation (minSaO2) mirrored those in the AHI. In adjusted analyses, repeated measurements of BMI (p < 0.009) emerged as the strongest independent longitudinal correlate of AHI and MinSaO2. The AHI worsens over time in renal transplant patients and longitudinal changes of this biomarker are directly related to simultaneous changes in BMI. Overweight/obesity, a potentially modifiable risk factor, is an important factor underlying the risk of SDB in this population.

A polymorphism in a major antioxidant gene (Kelch-like ECH-associated protein 1) predicts incident cardiovascular events in chronic kidney disease patients: an exploratory study.

OBJECTIVE: Oxidative stress is considered a major pathway conducive to cardiovascular disease in chronic kidney disease (CKD) patients. However, observational studies and clinical trials testing this relationship are controversial. The Nuclear factor-erythroid-2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) system is a major system regulating antioxidant mechanisms in living organisms. Owing to the fact that genes are transmitted randomly (Mendelian randomization), genetic variants may provide unconfounded assessment of putative causal risk factors. METHODS: We have therefore explored the association of eight polymorphisms in the Nrf2 gene and three polymorphisms in the Keap1 gene (capturing over 80% of the genetic variance in the same genes) with cardiovascular events in a multicenter cohort study of 758 CKD patients. RESULTS: During the follow-up period, 117 patients had fatal and nonfatal cardiovascular events and 42 died. The hazard rate of fatal and nonfatal cardiovascular outcomes was about twice higher in patients with the AA or the CA genotype (dominant model) in the rs110857735 polymorphism of the Keap1 gene (hazard rate: 1.85, 95% CI: 1.20-2.84, P = 0.005) than in those with the CC genotype. Further analyses adjusting for Framingham risk factors and CKD-specific risk factors and a bootstrapping validation analysis did not modify the strength of this association. No association was registered between other Keap1 and Nrf2 polymorphisms and cardiovascular disease in the same cohort. CONCLUSION: In this exploratory study a gene-variant in Keap1, a major gene regulating the antioxidant response, predicts incident cardiovascular events in CKD patients. This finding is in keeping with the hypothesis implicating oxidative stress in cardiovascular disease in this population.

A polymorphism in the major gene regulating serum uric acid associates with clinic SBP and the white-coat effect in a family-based study.

OBJECTIVES: Hyperuricemia associates with hypertension, but it is uncertain whether this relationship is causal in nature. Glucose transporter 9 (GLUT9) gene is a major genetic determinant of plasma uric acid levels in humans. Since polymorphisms are randomly distributed at mating (Mendelian randomization), studies based on GLUT9 polymorphisms may provide unconfounded assessment of the nature of the link between uric acid and hypertension. METHODS: We tested the association between uric acid, the rs734553 polymorphism of the GLUT9 gene and arterial pressure in a family-based study including 449 individuals in a genetically homogenous population in Southern Italy. RESULTS: Serum uric acid levels were strongly associated (P < 0.001) with all components of clinic and 24-h ambulatory blood pressures (BPs). However, only clinic SBP and the white-coat effect (the difference in clinic systolic and daytime systolic ambulatory blood pressure monitoring) associations remained significant after adjustment for classical risk factor and the estimated glomerular filtration rate. Serum uric acid was strongly associated with the risk allele (T) of the rs734553 polymorphism (P < 0.001). Furthermore, TT individuals showed higher clinic SBP (129 + SEM 1 mmHg) than GT (125 + 1 mmHg) and GG individuals (122 + 3 mmHg), as well as a higher white-coat effect (P = 0.02), confirming that the association between uric acid and these BP components is unconfounded by environmental risk factors. CONCLUSION: Results in this family-based study are compatible with the hypothesis that uric acid is a causal risk factor for hypertension. Trials testing uric acid-lowering interventions are needed to definitively establish the causal implication of hyperuricemia in human hypertension. [Corrected]

Association of a polymorphism in a gene encoding a urate transporter with CKD progression.

BACKGROUND AND OBJECTIVES: Hyperuricemia predicts a high risk for CKD progression but there is no large clinical trial in humans indicating that this relationship is causal in nature. The rs734553 single-nucleotide polymorphism (SNP) of the GLUT9 urate transporter gene was strongly associated with uric acid (UA) levels in a large meta-analysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This prospective study adopted the Mendelian randomization approach. The rs734553 SNP was used as an instrumental variable to investigate the relationship between UA and renal outcomes in a cohort of 755 patients with CKD who were enrolled between October 18, 2005, and October 2, 2008. The association between the polymorphism and UA was preliminary confirmed in a series of 211 healthy volunteers enrolled between January 1, 2001, and July 12, 2011, from the same geographic area as the patients with CKD. The study end point was a composite renal-end point (i.e., >30% decrease in the GFR, dialysis, or transplantation). Patients were followed up for a median of 36 months. RESULTS: In healthy individuals, serum UA levels were highest in homozygotes for the T allele (risk allele), intermediate in heterozygotes for the same allele, and lowest in those without the risk allele (P<0.001), but no such relationship was found in patients with CKD. In the CKD cohort, homozygotes (TT) and heterozygotes (GT) for the risk allele had a 2.35 times higher risk (hazard ratio, 2.35; 95% confidence interval, 1.25 to 4.42; P=0.008) of CKD progression. The risk for CKD progression by rs734553 remained unmodified in analyses adjusting for proteinuria, GFR, and other classical and CKD-peculiar risk factors. CONCLUSIONS: A GLUT9 polymorphism, which is strongly associated with serum UA levels in healthy individuals of the general population with normal renal function, holds a strong predictive power for CKD progression. These findings are compatible with the hypothesis that the link between UA and CKD progression is causal in nature.

eNOS and caveolin-1 gene polymorphisms interaction and intima media thickness: a proof of concept study in ESRD patients.

BACKGROUND: Caveolae are a prominent microdomain in endothelial cells and appropriate localization in caveolae is fundamental for endothelial nitric oxide synthase (eNOS) activity. Since the Glu298Asp variant in the eNOS gene alters caveolar localization of the corresponding enzyme, we tested the interaction between this variant and the rs4730751 polymorphism of the caveolin-1 (CAV-1) gene as related to arterial remodeling in end-stage renal disease (ESRD) patients. METHODS: One hundred and thirty-three ethnically homogeneous ESRD patients underwent carotid ultrasonographic studies to measure intima-media thickness (IMT) and carotid cross-sectional area (CSA). Genotyping was performed by high-throughput allelic discrimination assays on real-time PCR. RESULTS: Arterial remodeling was associated to the number of G alleles of CAV-1 polymorphism, GG homozygotes displaying an IMT and a CSA that were, respectively, 16% and 21% higher than those in patients without the risk allele (P < 0.012). In multiple linear regression analyses including the CAV-1 and the eNOS polymorphisms and adjusting for classical risk factors and risk factors peculiar to ESRD both polymorphisms were independent correlates of IMT (CAV-1: ß = 0.20, P = 0.01; eNOS ß = 0.25, P = 0.001) and CSA (CAV-1: ß = 0.20, P = 0.01: eNOS ß = 0.13, P = 0.09). Furthermore, strong interactions emerged between the two polymorphisms for explaining the variability in IMT (P = 0.001) and in CSA (P = 0.038) in these patients. CONCLUSION: Overall these findings form preliminary evidence that disturbed interaction between CAV-1 and eNOS may be of relevance for arterial disease in ESRD and perhaps in other human diseases.