Carolyn Brecklin

Effect of Relaxin in Two Models of Renal Mass Reduction

Background: Relaxin (Rlx), a 6-kD protein hormone, belongs to the insulin growth factor family. We have previously shown that Rlx reduces interstitial fibrosis in a model of chronic papillary necrosis. Hypothesis: The purpose of this study was to extend these observations to a model of renal injury induced by mass reduction. Material and Methods: Renal mass was reduced by either infarction or surgical excision of both poles, with removal of the contralateral kidney. Two weeks later, creatinine clearance was done and animals from both groups implanted with osmotic pumps delivering either Rlx (2 µg/h) or vehicle (Veh). Treatment was continued for 4 weeks. The severity of the glomerular injury was quantified by planimetric measurements. Renal function was assessed by creatinine clearance and plasma creatinine. Results: Rlx significantly decreased systolic blood pressure in animals with infarction. This was accompanied by a decrease in serum creatinine and a slight improvement in creatinine clearance. The severity of the glomerular lesion was reduced by Rlx (sclerosis index, Veh 1.16 ± 0.13 vs. Rlx 0.74 ± 0.16, p = 0.037). In the excision group the animals were normotensive. In this group, Rlx treatment was accompanied by a decrease in serum creatinine (Veh 1.01 ± 0.03 vs. Rlx 0.81 ± 0.05 mg/dl, p = 0.02) and an increase in GFR (Veh 0.90 ± 0.14 vs. Rlx 1.33 ± 0.11 ml/min, p = 0.03). The sclerosis index was also reduced. Conclusion: Rlx decreases renal injury by at least two mechanisms, one by lowering blood pressure as seen in the infarction model, the other independent of blood pressure as seen in the normotensive excision model where there was also a significant functional improvement.

Successful living related simultaneous pancreas-kidney transplant between identical twins.

Simultaneous pancreas-kidney transplant from living donors has been recently proposed as an effective therapeutic option in selected uremic patients with type I diabetes. We report the first simultaneous pancreas-kidney transplant performed between identical twins. Posttransplant, the recipient has been maintained on low dose cyclosporine to avoid recurrent auto-immune insulitis. At the 1-year follow-up, both donor and recipient are well with normal renal function and excellent glucose control. Simultaneous pancreas-kidney transplant between identical twins can be performed successfully using cyclosporine to prevent recurrent auto-immune insulitis.

Masked Hypertension and Elevated Nighttime Blood Pressure in CKD: Prevalence and Association with Target Organ Damage

BACKGROUND AND OBJECTIVES Masked hypertension and elevated nighttime BP are associated with increased risk of hypertensive target organ damage and adverse cardiovascular and renal outcomes in patients with normal kidney function. The significance of masked hypertension for these risks in patients with CKD is less well defined. The objective of this study was to evaluate the association between masked hypertension and kidney function and markers of cardiovascular target organ damage, and to determine whether this relationship was consistent among those with and without elevated nighttime BP. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This was a cross-sectional study. We performed 24-hour ambulatory BP in 1492 men and women with CKD enrolled in the Chronic Renal Insufficiency Cohort Study. We categorized participants into controlled BP, white-coat, masked, and sustained hypertension on the basis of clinic and 24-hour ambulatory BP. We obtained echocardiograms and measured pulse wave velocity in 1278 and 1394 participants, respectively. RESULTS The percentages of participants with controlled BP, white-coat, masked, and sustained hypertension were 49.3%, 4.1%, 27.8%, and 18.8%, respectively. Compared with controlled BP, masked hypertension independently associated with low eGFR (-3.2 ml/min per 1.73 m(2); 95% confidence interval, -5.5 to -0.9), higher proteinuria (+0.9 unit higher in log2 urine protein; 95% confidence interval, 0.7 to 1.1), and higher left ventricular mass index (+2.52 g/m(2.7); 95% confidence interval, 0.9 to 4.1), and pulse wave velocity (+0.92 m/s; 95% confidence interval, 0.5 to 1.3). Participants with masked hypertension had lower eGFR only in the presence of elevated nighttime BP (-3.6 ml/min per 1.73 m(2); 95% confidence interval, -6.1 to -1.1; versus -1.4 ml/min per 1.73 m(2); 95% confidence interval, -6.9 to 4.0, among those with nighttime BP <120/70 mmHg; P value for interaction with nighttime systolic BP 0.002). CONCLUSIONS Masked hypertension is common in patients with CKD and associated with lower eGFR, proteinuria, and cardiovascular target organ damage. In patients with CKD, ambulatory BP characterizes the relationship between BP and target organ damage better than BP measured in the clinic alone.

Earlier Onset and Greater Severity of Disordered Mineral Metabolism in Diabetic Patients With Chronic Kidney Disease

OBJECTIVE Disordered mineral metabolism is a common complication of chronic kidney disease (CKD) and a novel risk factor for CKD progression, cardiovascular disease, and mortality. Although diabetes is the leading cause of CKD and is associated with worse clinical outcomes than other etiologies, few studies have evaluated mineral metabolism in CKD according to diabetes status. RESEARCH DESIGN AND METHODS Using the Chronic Renal Insufficiency Cohort Study, we tested the hypothesis that diabetes is independently associated with lower serum calcium and higher serum phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23). RESULTS Compared with participants without diabetes (n = 1,936), those with diabetes (n = 1,820) were more likely to have lower estimated glomerular filtration rate (eGFR), lower serum albumin, and higher urinary protein excretion (all P < 0.001). Unadjusted serum phosphate, PTH, and FGF23 levels were higher and calcium was lower among those with compared with those without diabetes (all P < 0.001). After multivariate adjustment, diabetes remained a significant predictor of serum phosphate, PTH, and FGF23 but not calcium. The eGFR cut point at which 50% of participants met criteria for secondary hyperparathyroidism or elevated FGF23 was higher in participants with diabetes compared with those without (PTH: eGFR 30–39 vs. 20–29, P < 0.001; FGF23: eGFR 50–59 vs. 40–49, P < 0.001). CONCLUSIONS Disordered mineral metabolism begins earlier in the course of CKD and is more severe among CKD patients with compared with those without diabetes. Future studies should explore mechanisms for these differences and whether they contribute to excess risks of adverse clinical outcomes among diabetic patients with CKD.

Heart rate variability is a predictor of mortality in chronic kidney disease: a report from the CRIC Study.

Background/Aims: Low heart rate variability (HRV) is a risk factor for adverse outcomes in the general population. We aimed to determine the factors associated with HRV and evaluate the association between low HRV and clinical outcomes in patients with chronic kidney disease (CKD). Methods: A 10-second electrocardiogram was obtained at baseline in the Chronic Renal Insufficiency Cohort (CRIC) Study. HRV was measured by the standard deviation of all R-R intervals (SDNN) and the root mean square of successive differences between R-R intervals (RMSSD). Results: In 3,245 CRIC participants with available baseline SDNN and RMSSD, lower HRV was associated with older age, lack of exercise, heart failure, elevated phosphorus and hemoglobin A1c, and low estimated glomerular filtration rate. After a median follow-up of 4.2 years, in fully adjusted models, lower HRV was not associated with renal [SDNN: hazard rate, HR = 0.96 (95% confidence interval, CI 0.88-1.05); RMSSD: HR = 0.97 (95% CI 0.88-1.07)] or cardiovascular outcomes [SDNN: HR = 1.02 (95% CI 0.92-1.13); RMSSD: HR = 1.00 (95% CI 0.90-1.10)]. There was a nonlinear relationship between RMSSD and all-cause mortality with increased risk with both low and high RMSSD (p = 0.04). Conclusions: In a large cohort of patients with CKD, multiple risk factors for renal and cardiovascular diseases were associated with lower HRV. Lower HRV was not associated with increased risk for renal or cardiovascular outcomes, but both low and high RMSSD were associated with increased risk for all-cause mortality. In conclusion, HRV measured by RMSSD may be a novel and independent risk factor for mortality in CKD patients.

Prevalence, Predictors, and Outcomes of Pulmonary Hypertension in CKD

Pulmonary hypertension (PH) is associated with poor outcomes in the dialysis and general populations, but its effect in CKD is unclear. We evaluated the prevalence and predictors of PH measures and their associations with long-term clinical outcomes in patients with nondialysis-dependent CKD. Chronic Renal Insufficiency Cohort (CRIC) Study participants who had Doppler echocardiography performed were considered for inclusion. PH was defined as the presence of estimated pulmonary artery systolic pressure (PASP) >35 mmHg and/or tricuspid regurgitant velocity (TRV) >2.5 m/s. Associations between PH, PASP, and TRV and cardiovascular events, renal events, and all-cause mortality were examined using Cox proportional hazards models. Of 2959 eligible participants, 21% (n=625) had PH, with higher rates among those with lower levels of kidney function. In the multivariate model, older age, anemia, lower left ventricular ejection fraction, and presence of left ventricular hypertrophy were associated with greater odds of having PH. After adjusting for relevant confounding variables, PH was independently associated with higher risk for death (hazard ratio, 1.38; 95% confidence interval, 1.10 to 1.72) and cardiovascular events (hazard ratio, 1.23; 95% confidence interval, 1.00 to 1.52) but not renal events. Similarly, TRV and PASP were associated with death and cardiovascular events but not renal events. In this study of patients with CKD and preserved left ventricular systolic function, we report a high prevalence of PH. PH and higher TRV and PASP (echocardiographic measures of PH) are associated with adverse outcomes in CKD. Future studies may explain the mechanisms that underlie these findings.

Prevalence and Prognostic Significance of Apparent Treatment Resistant Hypertension in Chronic Kidney Disease: Report from the Chronic Renal Insufficiency Cohort Study

The association between apparent treatment resistant hypertension (ATRH) and clinical outcomes is not well studied in chronic kidney disease. We analyzed data on 3367 hypertensive participants in the Chronic Renal Insufficiency Cohort (CRIC) to determine prevalence, associations, and clinical outcomes of ATRH in nondialysis chronic kidney disease patients. ATRH was defined as blood pressure ≥140/90 mm Hg on ≥3 antihypertensives, or use of ≥4 antihypertensives with blood pressure at goal at baseline visit. Prevalence of ATRH was 40.4%. Older age, male sex, black race, diabetes mellitus, and higher body mass index were independently associated with higher odds of having ATRH. Participants with ATRH had a higher risk of clinical events than participants without ATRH—composite of myocardial infarction, stroke, peripheral arterial disease, congestive heart failure (CHF), and all-cause mortality (hazard ratio [95% confidence interval], 1.38 [1.22–1.56]); renal events (1.28 [1.11–1.46]); CHF (1.66 [1.38–2.00]); and all-cause mortality (1.24 [1.06–1.45]). The subset of participants with ATRH and blood pressure at goal on ≥4 medications also had higher risk for composite of myocardial infarction, stroke, peripheral arterial disease, CHF, and all-cause mortality (hazard ratio [95% confidence interval], (1.30 [1.12–1.51]) and CHF (1.59 [1.28–1.99]) than those without ATRH. ATRH was associated with significantly higher risk for CHF and renal events only among those with estimated glomerular filtration rate ≥30 mL/min per 1.73 m2. Our findings show that ATRH is common and associated with high risk of adverse outcomes in a cohort of patients with chronic kidney disease. This underscores the need for early identification and management of patients with ATRH and chronic kidney disease.

Illicit drug use, hypertension, and chronic kidney disease in the US adult population

Illicit drug use has been associated with chronic kidney disease (CKD) in select populations, but it is unknown whether the same association exists in the general population. By using data from the National Health and Nutrition Examination Survey 2005-2008, we conducted a cross-sectional analysis of 5861 adults who were questioned about illicit drug use, including cocaine, methamphetamines, and heroin, during their lifetime. The primary outcome was CKD as defined by an estimated glomerular filtration rate ≤60 mL/min/1.73 m(2) using the Chronic Kidney Disease Epidemiology Collaboration equation or by microalbuminuria. We also examined the association between illicit drug use and blood pressure (BP) ≥120/80, ≥130/85, and ≥140/90 mm Hg. Logistic regression was used to examine the association between illicit drug use and CKD and BP. Mean estimated glomerular filtration rate was similar between illicit drug users and nonusers (100.7 vs 101.4 mL/min/1.73 m(2), P = 0.4), as was albuminuria (5.7 vs 6.0 mg/g creatinine, P = 0.5). Accordingly, illicit drug use was not significantly associated with CKD in logistic regression models (odds ratio [OR], 0.98; confidence interval [CI], 0.75-1.27) after adjusting for other important factors. However, illicit drug users had higher systolic (120 vs 118 mm Hg, P = 0.04) and diastolic BP (73 vs 71 mm Hg, P = 0.0003) compared with nonusers. Cocaine use was independently associated with BP ≥130/85 mm Hg (OR, 1.24; CI, 1.00-1.54), especially when used more during a lifetime (6-49 times; OR, 1.42; CI, 1.06-1.91). In a representative sample of the US population, illicit drug use was not associated with CKD, but cocaine users were more likely to have elevated BP.

Lipidomic Signature of Progression of Chronic Kidney Disease in the Chronic Renal Insufficiency Cohort

Introduction Human studies report conflicting results on the predictive power of serum lipids on the progression of chronic kidney disease. We aimed to systematically identify the lipids that predict progression to end-stage kidney disease. Methods From the Chronic Renal Insufficiency Cohort, 79 patients with chronic kidney disease stages 2 to 3 who progressed to end-stage kidney disease over 6 years of follow-up were selected and frequency matched by age, sex, race, and diabetes with 121 nonprogressors with less than 25% decline in estimated glomerular filtration rate during the follow-up. The patients were randomly divided into training and test sets. We applied liquid chromatography-mass spectrometry-based lipidomics on visit year 1 samples. Results We identified 510 lipids, of which the top 10 coincided with false discovery threshold of 0.058 in the training set. From the top 10 lipids, the abundance of diacylglycerols and cholesteryl esters was lower, but that of phosphatidic acid 44:4 and monoacylglycerol 16:0 was significantly higher in progressors. Using logistic regression models, a multimarker panel consisting of diacylglycerols and monoacylglycerol independently predicted progression. The c-statistic of the multimarker panel added to the base model consisting of estimated glomerular filtration rate and urine protein-to-creatinine ratio as compared with that of the base model was 0.92 (95% confidence interval: 0.88–0.97) and 0.83 (95% confidence interval: 0.76–0.90, P < 0.01), respectively, an observation that was validated in the test subset. Discussion We conclude that a distinct panel of lipids may improve prediction of progression of chronic kidney disease beyond estimated glomerular filtration rate and urine protein-to-creatinine ratio when added to the base model.

Recruitment of Hispanics into an observational study of chronic kidney disease: the Hispanic Chronic Renal Insufficiency Cohort Study experience.

Despite the large burden of chronic kidney disease (CKD) in Hispanics, this population has been underrepresented in research studies. We describe the recruitment strategies employed by the Hispanic Chronic Renal Insufficiency Cohort Study, which led to the successful enrollment of a large population of Hispanic adults with CKD into a prospective observational cohort study. Recruitment efforts by bilingual staff focused on community clinics with Hispanic providers in high-density Hispanic neighborhoods in Chicago, academic medical centers, and private nephrology practices. Methods of publicizing the study included church meetings, local Hispanic print media, Spanish television and radio stations, and local health fairs. From October 2005 to July 2008, we recruited 327 Hispanics aged 21-74 years with mild-to-moderate CKD as determined by age-specific estimated glomerular filtration rate (eGFR). Of 716 individuals completing a screening visit, 49% did not meet eGFR inclusion criteria and 46% completed a baseline visit. The mean age at enrollment was 57.1 and 67.1% of participants were male. Approximately 75% of enrolled individuals were Mexican American, 15% Puerto Rican, and 10% had other Latin American ancestry. Eighty two percent of participants were Spanish-speakers. Community-based and academic primary care clinics yielded the highest percentage of participants screened (45.9% and 22.4%) and enrolled (38.2% and 24.5%). However, academic and community-based specialty clinics achieved the highest enrollment yield from individuals screened (61.9% to 71.4%). A strategy focused on primary care and nephrology clinics and the use of bilingual recruiters allowed us to overcome barriers to the recruitment of Hispanics with CKD.