The objective of this paper is development of an inexpensive point-of-care sensor for detecting the primary heart failure marker peptide, NT-proBNP. The device technology is based on an antibody sandwich assay, but with three innovative aspects. First, chemical amplification is carried out via oxidation of silver nanoparticles (NPs) attached to signaling antibodies rather than by enzymatic amplification. The electrochemical method is faster and eliminates the need for long-term storage of enzymes. Second, the antibody sandwich is formed on mobile magnetic beads. This enhances the rate of mass transfer of the biomarker and the signaling antibody to the primary detection antibody, which is immobilized on the magnetic beads. Third, the sensor itself is fabricated on a paper platform with screen-printed electrodes. This coupled with assembly by simple paper folding, keeps the cost of the sensor low. Here, we report on two separate assays. The first is based on a simple biotin-streptavidin conjugate, which is a preliminary model for the antibody assay. The results indicate a detection limit of 2.1 pM of silver NPs and an assay time of 7 min. The actual NT-proBNP antibody assay takes somewhat longer, and the dynamic detection range is higher: 2.9–582 nM. On the basis of the results presented in this paper, we conclude that this inexpensive paper-based sensor represents a viable technology for point-of-care testing of NT-proBNP, but nevertheless several challenges remain prior to clinical implementation. These include attaining a lower detection limit and better reproducibility, and optimizing the device for human blood.

BackgroundAs antiretroviral therapy efficacy improves, HIV is gradually being recognized more as a chronic disease within the aging HIV-infected population. While these individuals are surviving into old age, they may, however, be experiencing “accelerated aging” with greater declines in physical function than that observed among comparably matched individuals free of HIV. This decline is not well understood and it remains unclear if physical decline correlates with the degree of immunosuppression based on CD4 lymphocyte nadir.MethodsIn a cross-sectional study of accelerated aging in the older HIV-infected population on antiretroviral therapy (ART), physical performance evaluations were completed on a cohort of 107 HIV-infected subjects, age 50 years or older (with no HIV-1 RNA >200 copies/mL in the prior 12 months), and compared to reference ranges for age- and gender-matched HIV-uninfected persons. Physical performance testing consisted of four validated assessments: the 2.4-meter walk, 30-second chair stand, grip strength and 6-minute walk test.ResultsWhen compared to age- and gender-matched HIV-uninfected reference controls, older HIV-infected persons had diminished physical function. No correlation was found between physical function and degree of immunosuppression as determined by pre-ART CD4 nadir.ConclusionsDespite improved survival, HIV–infected adults on suppressive ART have diminished physical function compared to HIV-uninfected persons. The degree of HIV-associated immunosuppression does not correlate with the observed degree of physical function decline in older HIV-infected persons, suggesting the decline is mediated by other mechanisms.

Antiretroviral therapy (ART) has prolonged lives of persons living with HIV/AIDS (PLWHA), resulting in greater incidence of aging-related diseases and disability. Physical activity (PA) is recommended for healthy aging, but little is known about PA in older PLWHA. The purpose of this study was to objectively assess PA levels in older PLWHA and the associations with physical function. Twenty-one PLWHA, ≥50 years old, on ART with undetectable HIV-1 viral loads, wore an accelerometer to assess PA, including number of steps, activity intensity, and energy expenditure over 7 days. A physical function performance battery assessing aerobic capacity, strength, and gait speed was also completed. Average age was 66, and 67% were male. An average of 3,442 (interquartile range: 4,613) steps were walked daily, with 254.9 kcals expended. Participants spent most waking hours (75%) sedentary, with minimal hours (24%) in light-intensity activity. Only 5 min per day (35 min per week), on average, were spent in moderate-to-vigorous physical activity (MVPA). Maximal gait speed and 6-min walk test significantly correlated (p < .05) with all PA outcomes. Usual gait speed significantly correlated with all PA outcomes, except for daily kcals and light-intensity activity. Greater PA was associated with better physical performance, while high sedentary time was associated with poorer performance. To our knowledge, this is the first study to objectively measure PA in older PLWHA. Our findings indicate that older PLWHA accumulate substantial sedentary time. Most (86%) do not achieve recommended MVPA levels. This activity profile was associated with poor physical function. Providers should promote PA among PLWHA.

Background In 2006, the Centers for Disease Control and Prevention (CDC) recommended non‐targeted, opt‐out HIV screening in all healthcare settings, including emergency departments (EDs). Multiple HIV testing programs have been implemented in EDs across the United States with varying designs and testing platforms. We report findings from a free, non‐targeted, rapid HIV testing program in 2 EDs in the Southeastern United States. Methods From 2008 to 2012, adults ≥18 years of age were offered free rapid HIV testing using an oral swab test (OraQuick ADVANCE Rapid HIV‐1/2 antibody test) in the EDs of a large academic medical center and an affiliated community hospital in Durham, North Carolina. Results In total, 5443 ED patients were offered HIV testing. The overall acceptance rate was 66.9% (3639/5443). Younger persons were significantly more likely to accept testing (78.2% for 18–29 years old vs 67.1% for ≥30 years old; P < 0.001) as were Black participants (72.6% Black vs 66.5% White; P < 0.001). Acceptance rates improved significantly after opt‐out oral consent replaced written consent (71.3% vs 63.1%; P < 0.001). Seven new HIV diagnoses were confirmed during the testing program, resulting in a seropositivity rate of 0.19% (7/3639). There were 8 false–positive rapid oral HIV tests (positive predictive value = 46.7%). Conclusions Although the number of new HIV diagnoses was low, implementation of this rapid, non‐targeted ED screening program was feasible with high acceptance rates, particularly after introducing the opt‐out oral consent approach.

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