Research Spotlight

Vasudevan, A., T. Bottiglieri, K. M. Tecson, M. Sathyamoorthy, J. M. Schussler, C. E. Velasco, L. R. Lopez, C. Swift, M. Peterson, J. Bennett-Firmin, R. Schiffmann and P. A. McCullough (2016). “Residual thromboxane activity and oxidative stress: Influence on mortality in patients with stable coronary artery disease.” Coron Artery Dis: 2016 Dec [Epub ahead of print].

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BACKGROUND: Aspirin use is effective in the prevention of cardiovascular disease; however, not all patients are equally responsive to aspirin. Oxidative stress reflected by F2-isoprostane [8-iso-prostaglandin-F2alpha (8-IsoPGF2alpha)] is a potential mechanism of failure of aspirin to adequately inhibit cyclooxygenase-1. The objective was to examine the relation between all-cause mortality and the concentrations of urinary 11-dehydro thromboxane B2 (11dhTxB2) and 8-IsoPGF2alpha in patients with stable coronary artery disease (CAD). METHODS: The data for this analysis are from a prospective study in which patients were categorized into four groups based on the median values of 11dhTxB2 and 8-IsoPGF2alpha. RESULTS: There were 447 patients included in this analysis with a median (range) age of 66 (37-91) years. The median (range) values of 11dhTxB2 and 8-IsoPGF2alpha were 1404.1 (344.2-68296.1) and 1477.9 (356.7-19256.3), respectively. A total of 67 (14.9%) patients died over a median follow-up of 1149 days. The reference group for the Cox proportional hazards survival analysis was patients with values of 11dhTxB2 and 8-IsoPGF2alpha below their corresponding medians. Adjusting for the age and sex, patients with values of 11dhTxB2 greater than the median had a significantly higher risk of mortality when compared with the reference group (high 11dhTxB2 and low 8-IsoPGF2alphaadj: hazard ratio: 3.2, 95% confidence interval: 1.6-6.6, P=0.002; high 11dhTxB2 and 8-IsoPGF2alphaadj: hazard ratio: 3.6, 95% confidence interval: 1.8-7.3, P<0.001). The findings were similar when we adjusted for the comorbidities of cancer, kidney function, and ejection fraction. CONCLUSION: We found that 11dhTxB2 appears to be a better prognostic marker for mortality as compared with 8-IsoPGF2alpha, suggesting aspirin resistance itself is a stronger independent determinant of death in CAD patients treated with aspirin.

Weir, M. R., T. C. Pearson, A. Patel, V. R. Peddi, R. Kalil, J. Scandling, L. Chan, P. Baliga, L. Melton, S. Mulgaonkar, T. Waid, H. Schaefer, N. Youssef, L. Anandagoda, D. McCollum, S. Lawson and R. Gordon (2017). “Long-term follow-up of kidney transplant recipients in the spare-the-nephron-trial.” Transplantation 101(1): 157-165.

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In the Spare-the-Nephron (STN) Study, kidney transplant recipients randomized about 115 days posttransplant to convert from CNI (calcineurin inhibitor)/MMF to sirolimus (SRL)/MMF had a significantly greater improvement in measured GFR (mGFR) at 12 months compared with those kept on CNI/MMF. The difference at 24 months was not statistically significant. From 14 top enrolling centers, 128 of 175 patients identified with a functioning graft at 2 years consented to enroll in an observational, noninterventional extension study to collect retrospectively and prospectively annual follow-up data for the interval since baseline (completion of the parent STN study at 24 months posttransplant). Overall, 11 patients died, including 5 (7.6%) in the SRL/MMF group and 6 (9.7%) in the CNI/MMF group. Twenty-two grafts have been lost including 10 (15.2%) in the SRL/MMF arm and 12 (19.4%) in the CNI/MMF arm. Death and chronic rejection were the most common causes of graft loss in both arms. There were modestly more cardiovascular events in the MMF/SRL group. Estimated creatinine clearance (Cockcroft-Gault) from baseline out to 6 additional years (8 years posttransplant, ITT analysis, SRL/MMF, n = 34; CNI/MMF, n = 26) was 63.2 +/- 28.5 mL/min/1.73 m in the SRL/MMF group and 59.2 +/- 27.2 mL/min/1.73 m in the CNI/MMF group and was not statistically significant, but there is a clinically meaningful trend for improved long-term renal function in the SRL/MMF group compared with the CNI/MMF group. The long-term decision for immunosuppression needs to be carefully individualized.

Wesson, D. E. (2016). “Does serum hco3 predict risk for cardiovascular disease?” Am J Nephrol 45(2): 115-117.

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Diets high in acid of developed societies that do not cause metabolic acidosis in patients with chronic kidney disease nevertheless appear to cause acid retention with associated morbidity, particularly in those with reduced glomerular filtration rate. Here we used a rat 2/3 nephrectomy model of chronic kidney disease to study induction and maintenance of acid retention and its consequences on indicators of kidney and bone injury. Dietary acid was increased in animals eating base-producing soy protein with acid-producing casein and in casein-eating animals with added ammonium chloride. Using microdialysis to measure the kidney cortical acid content, we found that nephrectomized animals had greater acid retention than sham-operated animals when both ate the soy diet. Each increment in dietary acid further increased acid retention more in nephrectomized than in sham rats. Nephrectomized and sham animals achieved similar steady-state daily urine net acid excretion in response to increments in dietary acid but nephrectomized animals took longer to do so, contributing to greater acid retention that was maintained until the increased dietary acid was stopped. Acid retention was associated with increased urine excretion of both N-acetyl-β-D-glucosaminidase and deoxypyridinoline, greater in nephrectomized than control rats, consistent with kidney tubulointerstitial and bone matrix injury, respectively. Greater acid retention in nephrectomized than control animals was induced by a slower increase in urinary net acid excretion rate in response to the increment in dietary acid and also maintained until the dietary acid increment was stopped. Thus, acid retention increased biomarkers of kidney and bone injury in the urine, supporting untoward consequences to these two tissues.

Yardley, D. A., J. Reeves, E. C. Dees, C. Osborne, D. Paul, F. Ademuyiwa, H. Soliman, T. Guthrie, J. Andersen, L. Krekow, J. Choksi, B. Daniel, M. Danso, A. Favret, S. Oommen, A. Brufsky, J. L. Bromund, Y. Lin, A. B. Ibrahim and P. D. Richards (2016). “Ramucirumab with eribulin versus eribulin in locally recurrent or metastatic breast cancer previously treated with anthracycline and taxane therapy: A multicenter, randomized, phase ii study.” Clin Breast Cancer 16(6): 471-479.

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BACKGROUND: Use of antiangiogenic agents in treatment of metastatic breast cancer (MBC) remains controversial. We evaluated the efficacy and safety of ramucirumab and eribulin versus eribulin alone as third- to fifth-line therapy in women with advanced breast cancer. PATIENTS AND METHODS: In this randomized (1:1), open-label, phase II study, US women aged 18 years or older with 2 to 4 previous chemotherapy regimens for locally recurrent or MBC, previous anthracycline and taxane treatment, and Eastern Cooperative Oncology Group performance status of 0 or 1 received ramucirumab with eribulin or eribulin alone in 21-day cycles (eribulin 1.4 mg/m2 intravenously on days 1 and 8; ramucirumab 10 mg/kg intravenously on day 1). Randomization was stratified according to previous antiangiogenic therapy and triple-negative status. The primary end point was progression-free survival (PFS) in the intention to treat population. RESULTS: One hundred forty-one women were randomized to ramucirumab with eribulin (n = 71) or eribulin alone (n = 70). Median PFS for ramucirumab with eribulin was 4.4 months (95% confidence interval [CI], 3.1-6.7) compared with 4.1 months (95% CI, 3.2-5.6) for eribulin (hazard ratio [HR], 0.83; 95% CI, 0.56-1.23; P = .35). Median overall survival in patients who received ramucirumab with eribulin was 13.5 months (95% CI, 10.4-17.9) compared with 11.5 months (95% CI, 9.0-17.3) in patients who received eribulin alone (HR, 0.91; 95% CI, 0.59-1.41; P = .68); objective response rate was 21% (13 of 62 patients) for the combination and 28% (17 of 60 patients) for eribulin alone. No unexpected toxicity was identified for the combination. CONCLUSION: Ramucirumab combined with eribulin did not significantly improve PFS in advanced MBC.

Wesson, D. E., J. Pruszynski, W. Cai and J. Simoni (2016). “Acid retention with reduced glomerular filtration rate increases urine biomarkers of kidney and bone injury.” Kidney Int 45(2): 115-117.

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Diets high in acid of developed societies that do not cause metabolic acidosis in patients with chronic kidney disease nevertheless appear to cause acid retention with associated morbidity, particularly in those with reduced glomerular filtration rate. Here we used a rat 2/3 nephrectomy model of chronic kidney disease to study induction and maintenance of acid retention and its consequences on indicators of kidney and bone injury. Dietary acid was increased in animals eating base-producing soy protein with acid-producing casein and in casein-eating animals with added ammonium chloride. Using microdialysis to measure the kidney cortical acid content, we found that nephrectomized animals had greater acid retention than sham-operated animals when both ate the soy diet. Each increment in dietary acid further increased acid retention more in nephrectomized than in sham rats. Nephrectomized and sham animals achieved similar steady-state daily urine net acid excretion in response to increments in dietary acid but nephrectomized animals took longer to do so, contributing to greater acid retention that was maintained until the increased dietary acid was stopped. Acid retention was associated with increased urine excretion of both N-acetyl-beta-D-glucosaminidase and deoxypyridinoline, greater in nephrectomized than control rats, consistent with kidney tubulointerstitial and bone matrix injury, respectively. Greater acid retention in nephrectomized than control animals was induced by a slower increase in urinary net acid excretion rate in response to the increment in dietary acid and also maintained until the dietary acid increment was stopped. Thus, acid retention increased biomarkers of kidney and bone injury in the urine, supporting untoward consequences to these two tissues.