Noncoding RNAs such as miRNAs (miRs) are extensively researched as a novel class of cancer biomarkers. Herein, we describe a new method to sensitively determine the levels miRNAs via dual signal readout involving competitive hybridization between the miR-21 target and its biotinylated analog towards the same thiolated DNA probe attached onto the surface of gold nanoparticles. Hybridization of the DNA probes by the biotinylated miRs followed by conjugation with streptavidin-horseradish peroxidase, which catalyzes the oxidation of o-phenylenediamine into 2,3-diaminophenazine, allows detecting the target using fluorescence and electrochemistry. The two signals varied in a miRNA concentration-dependent manner. The bioplatform has limits of detection of 15 fmol/L and 19 fmol/L (0.15 and 0.19 attomol in 20 mu L, respectively). Furthermore, it displays a wide linear calibration range varying from 19 fmol/L to 100 pmol/L and 15 fmol/L to 100 pmol/L using voltamperometry and fluorescence, respectively. The bioplatform is able to provide very low detection limits without any DNA/RNA amplification step, an excellent selectivity toward non-complementary miRs along with an acceptable distinction with a single nucleotide mismatched sequence. Finally, the method was used to determine miR-21 expression levels in blood sera from patients diagnosed with breast cancer.

Rationale & Objective: Evidence is limited on how estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (UACR) relate to dementia at different ages. We evaluated eGFR and UACR in midlife and older age as risk factors for dementia. Additionally, we assessed whether the association between eGFR and dementia is altered when cystatin C and beta(2)-microglobulin (B2M) levels are used for GFR estimation. Study Design: Prospective cohort study. Setting & Participants: Two baselines from the Atherosclerosis Risk in Communities (ARIC) Study were used: visit 4 (1996-199 8), including 9,967 participants 54 to 74 years old, and visit 5 (2011-2013), including 4,626 participants 70 to 90 years old. Participants were followed up until 2017. Predictors: Log(UACR); eGFR based on creatinine, cystatin C, creatinine and cystatin C, or B2M levels (denoted as eGFR(cr), eGFR(cys), eGFR(cr-cys), and eGFR(B2M)). Outcome: Incident dementia. Analytical Approach: Multivariable Cox proportional hazards regression models fit separately for each of the 5 predictors and based on a change in the predictor equivalent to the interquartile range for that predictor at visit 4 (IQR(V4)). eGFR models were adjusted for log(UACR) and log(UACR) models were adjusted for eGFR(cys). Results: We observed 1,821 dementia cases after visit 4 and 438 cases after visit 5. Dementia risk increased with higher albuminuria levels (HRs per IQR(V4) [equivalent to 4.2-fold greater log albuminuria] of 1.15 [95% CI, 1.09-1.21] after visit 4 and 1.27 [95% CI, 1.13-1.42] after visit 5). An association with lower eGFR was seen for only eGFR(cys) (HRs per IQR(V4) [equivalent to 24.3 mL/min/1.73 m(2) lesser eGFR(cys)] of 1.12 [95% CI, 1.0 4-1.21] after visit 4 and 1.30 [95% CI, 1.12-1.52] after visit 5) and eGFR(B2M) (HRs per IQR(V4) [equivalent to 18.3 mL/min/1.73 m(2) lesser eGFR(B2M)] of 1.15 [95% CI, 1.07-1.23] after visit 4 and 1.34 [95% CI, 1.17-1.55] after visit 5). Differences between these associations in midlife and older age were not statistically significant. Limitations: Changes in potentially time-varying covariates were not measured. Dementia was not subclassified by cause. Conclusions: Albuminuria was consistently associated with dementia incidence. Lower eGFR based on cystatin C or B2M, but not creatinine, levels was also associated with dementia. Risk associations were similar when kidney measures were assessed at midlife and older age.