Programmable self-regulated molecular buffers for precise sustained drug delivery.

Unlike artificial nanosystems, biological systems are ideally engineered to respond to their environment. As such, natural molecular buffers ensure precise and quantitative delivery of specific molecules through self-regulated mechanisms based on Le Chatelier's principle. Here, we apply this principle to design self-regulated nucleic acid molecular buffers for the chemotherapeutic drug doxorubicin and the antimalarial agent quinine. We show that these aptamer-based buffers can be programmed to maintain any specific desired concentration of free drug both in vitro and in vivo and enable the optimization of the chemical stability, partition coefficient, pharmacokinetics and biodistribution of the drug. These programmable buffers can be built from any polymer and should improve patient therapeutic outcome by enhancing drug activity and minimizing adverse effects and dosage frequency.

Higher Na+-Ca2+ Exchanger Function and Triggered Activity Contribute to Male Predisposition to Atrial Fibrillation.

Male sex is one of the most important risk factors of atrial fibrillation (AF), with the incidence in men being almost double that in women. However, the reasons for this sex difference are unknown. Accordingly, in this study, we sought to determine whether there are sex differences in intracellular Ca2+ homeostasis in mouse atrial myocytes that might help explain male predisposition to AF. AF susceptibility was assessed in male (M) and female (F) mice (4-5 months old) using programmed electrical stimulation (EPS) protocols. Males were 50% more likely to develop AF. The Ca2+ transient amplitude was 28% higher in male atrial myocytes. Spontaneous systolic and diastolic Ca2+ releases, which are known sources of triggered activity, were significantly more frequent in males than females. The time to 90% decay of Ca2+ transient was faster in males. Males had 54% higher Na+-Ca2+ exchanger (NCX1) current density, and its expression was also more abundant. L-type Ca2+ current (ICaL) was recorded with and without BAPTA, a Ca2+ chelator. ICaL density was lower in males only in the absence of BAPTA, suggesting stronger Ca2+-dependent inactivation in males. CaV1.2 expression was similar between sexes. This study reports major sex differences in Ca2+ homeostasis in mouse atria, with larger Ca2+ transients and enhanced NCX1 function and expression in males resulting in more spontaneous Ca2+ releases. These sex differences may contribute to male susceptibility to AF by promoting triggered activity.

Pregnancy-induced increased heart rate is independent of thyroid hormones.

BACKGROUND: The heart rate increases by 10-20 beats per minute (bpm) throughout pregnancy in women, reaching maximum heart rate in the third trimester. During pregnancy, important changes in thyroid hormones also occur, with increases of up to 50% in the levels of triiodothyronine (T3), the biological active thyroid hormone. In addition, T3 has been shown to regulate cardiac electrophysiology. OBJECTIVE: Thus, in the present study the potential contribution of T3 in pregnancy-induced increased heart rate was explored. METHODS: We compared the heart rate between nonpregnant and pregnant mice under control conditions and after altering thyroid hormone levels with T3 and propylthiouracil (PTU, an antithyroid drug) treatments. RESULTS: Consistent with the clinical data, we found a 58% rise in T3 levels during pregnancy in mice. Although pregnant mice had a higher baseline heart rate (607 ± 8 bpm, P = .004) and higher T3 levels (1.9 ± 0.4 nM, P = .0005) than nonpregnant mice (heart rate: 546 ± 16 bpm; T3 levels: 1.2 ± 0.1 nM), their heart rate responded similarly to T3 treatment as nonpregnant mice (nonpregnant: Δ130 ± 22 bpm; pregnant: Δ126 ± 17 bpm, P = .858). Additionally, the heart rate remained significantly elevated (607 ± 11 bpm, P = .038) and comparable to untreated pregnant mice, after the use of the antithyroid drug PTU, although T3 levels (1.3 ± 0.2 nM, P = .559) returned to nonpregnant values. CONCLUSION: Based on these results, it is unlikely that T3 contributes significantly to the pregnancy-induced increased heart rate.

Contribution of estrogen to the pregnancy-induced increase in cardiac automaticity.

BACKGROUND: The heart rate progressively increases throughout pregnancy, reaching a maximum in the third trimester. This elevated heart rate is also present in pregnant mice and is associated with accelerated automaticity, higher density of the pacemaker current If and changes in Ca2+ homeostasis in sinoatrial node (SAN) cells. Strong evidence has also been provided showing that 17ß-estradiol (E2) and estrogen receptor α (ERα) regulate heart rate. Accordingly, we sought to determine whether E2 levels found in late pregnancy cause the increased cardiac automaticity associated with pregnancy. METHODS AND RESULTS: Voltage- and current-clamp experiments were carried out on SAN cells isolated from female mice lacking estrogen receptor alpha (ERKOα) or beta (ERKOß) receiving chronic E2 treatment mimicking late pregnancy concentrations. E2 treatment significantly increased the action potential rate (284 ± 24 bpm, +E2 354 ± 23 bpm, p = 0.040) and the density of If (+52%) in SAN cells from ERKOß mice. However, If density remains unchanged in SAN cells from E2-treated ERKOα mice. Additionally, E2 also increased If density (+67%) in nodal-like human-induced pluripotent stem cell-derived cardiomyocytes (N-hiPSC-CM), recapitulating in a human SAN cell model the effect produced in mice. However, the L-type calcium current (ICaL) and Ca2+ transients, examined using N-hiPSC-CM and SAN cells respectively, were not affected by E2, indicating that other mechanisms contribute to changes observed in these parameters during pregnancy. CONCLUSION: The accelerated SAN automaticity observed in E2-treated ERKOß mice is explained by an increased If density mediated by ERα, demonstrating that E2 plays a major role in regulating SAN function during pregnancy.

Pregnancy and oestrogen regulate sinoatrial node calcium homeostasis and accelerate pacemaking.

Aims: During pregnancy, there is a significant increase in heart rate (HR) potentially associated with an increased risk of arrhythmias or exacerbation of pre-existing cardiac conditions endangering both mother and foetus. Calcium homeostasis plays an important role in regulating automaticity of the sinoatrial node (SAN); however, its contribution to the accelerated HR during pregnancy remains unknown. Methods and results: Using murine SAN cells, we showed that pregnancy increased L-type Ca2+ current (ICaL) and CaV1.3 mRNA expression, whereas T-type Ca2+ current (ICaT) and its underlying channel were unchanged. Analysis of SAN intra-cellular Ca2+ oscillations showed that the rate of spontaneous Ca2+ transients was significantly higher in pregnant mice along with a higher mRNA expression of ryanodine receptor. Assessment of supra-ventricular arrhythmias using programmed electrical stimulation protocols on anaesthetized mice revealed higher susceptibility in pregnancy. Of note, the modifications associated with pregnancy were reversible following delivery. Furthermore, chronic administration of 17ß-estradiol (E2) to nodal-like human-induced pluripotent stem cell-derived cardiomyocytes (N-hiPSC-CM), control mice, oestrogen-receptor-ß knockout (ERKOß) but not ERKOα mice, accelerated cardiac automaticity, recapitulating the pregnancy phenotype in both mouse and human SAN cell models. Conclusion: Together, these results indicate that pregnancy considerably alters intra-cellular Ca2+ homeostasis sustaining faster HR during pregnancy. Importantly, these changes were dependent on an oestrogen receptor α (ERα) mechanism that resulted in increased ICaL and spontaneous Ca2+ release from the sarcoplasmic reticulum, highlighting a novel role for oestrogen in regulating HR.

Adding a Social Marketing Campaign to a School-Based Nutrition Education Program Improves Children's Dietary Intake: A Quasi-Experimental Study.

BACKGROUND: Evidence supports the use of social marketing campaigns to improve nutrition knowledge and reinforce the effects of nutrition education programs. However, the additional effects of parent-focused social marketing with nutrition education have received little attention. OBJECTIVE: Our aim was to assess the impact of the Iowa Nutrition Network's school-based nutrition education program (Building and Strengthening Iowa Community Support for Nutrition and Physical Activity [BASICS]) and the benefits of adding a multichannel social marketing intervention (BASICS Plus) to increase parent-directed communication. DESIGN AND INTERVENTION: A quasi-experimental design with three study conditions compared a school-based nutrition education program (BASICS) with a school-based and social marketing intervention (BASICS Plus) and a no-treatment comparison group. PARTICIPANTS/SETTING: The study included 1,037 third-grade students attending 33 elementary schools and their parents. MAIN OUTCOME MEASURES: Measures included parents' reports of their children's in-home consumption of fruits and vegetables (F/V) and use of low-fat/fat-free milk. Data on F/V were collected using a modified version of the University of California Cooperative Extension Food Behavior Checklist; and data on milk use were collected using two questions from the National Health and Nutrition Examination Survey. STATISTICAL ANALYSES: Multilevel, mixed-effect regression models that account for correlation within repeated measures and children within school were used to compare the mean change over time in the outcome variable for one study group with the mean change over time for another study group. RESULTS: Children in BASICS increased mean consumption of fruit by 0.16 cups (P=0.04) compared with children in the comparison group. Children in BASICS Plus increased mean consumption of fruit by 0.17 cups (P=0.03) and mean consumption of vegetables by 0.13 cups (P=0.02). Children in BASICS Plus were 1.3 times (P=0.05) more likely to use low-fat/fat-free milk than children in either the BASICS group or the comparison group. CONCLUSIONS: Gaining parents' attention and engaging them in healthy eating practices for their children can be a useful way to increase the effectiveness of school-based nutrition education programs. This study demonstrates the benefits of incorporating a parent-focused social marketing campaign in nutrition education interventions.

Eat Smart, Live Strong intervention increases fruit and vegetable consumption among low-income older adults.

This study evaluated the impact of a four-session interactive nutrition education program-Eat Smart, Live Strong (ESLS)-on the consumption of fruit and vegetables by low-income older adults. A pre-post quasi-experimental design study was conducted with a longitudinal sample of 614 low-income Supplemental Nutrition Assistance Program (SNAP) participants and those eligible for SNAP, aged 60 to 80 years, in 17 intervention and 16 comparison senior centers in Michigan. The study compared participants' self-reports of their consumption of fruit and vegetables using a modified version of the University of California Cooperative Extension Food Behavior Checklist. ESLS increased participants' average daily consumption of fruit by 0.2 cups (P < 0.05) and vegetables by 0.31 cups (P < 0.01). ESLS, a four-session, cognitive-behavioral nutrition education program is an effective curriculum for helping low-income older adults eat more fruit and vegetables.

Evaluating the Impact of Six Supplemental Nutrition Assistance Program Education Interventions on Children's At-Home Diets.

BACKGROUND: Nutrition education in the Supplemental Nutrition Assistance Program Education (SNAP-Ed) is designed to promote healthy eating behaviors in a low-income target population. PURPOSE: To evaluate the effectiveness of six SNAP-Ed interventions delivered in child care centers or elementary school settings in increasing participating children's at-home fruit and vegetable (F/V) consumption by 0.3 cups per day and use of fat-free or low-fat milk instead of whole or reduced-fat milk during the prior week. METHOD: Clustered randomized or quasi-experimental clustered trials took place in child care centers or elementary schools between 2010 and 2012. Parents of children at intervention and control sites completed baseline and follow-up surveys about their child's at home F/V consumption and other dietary behaviors. RESULTS: One of the six interventions was successful in meeting the objective of increasing children's F/V consumption by 0.3 cups per day. For three of the six interventions, there was a small but statistically significant increase in F/V consumption and/or use of low-fat or fat-free milk. CONCLUSION: Although not all interventions were effective, these findings suggest that it is possible for some SNAP-Ed interventions to improve dietary habits among low-income children among some families. The effective interventions appear to have benefited from implementation experience and sustained efforts at intervention refinement and improvement.

Multivalent group A streptococcal vaccine elicits bactericidal antibodies against variant M subtypes.

Group A streptococci cause a wide spectrum of clinical illness. One of several strategies for vaccine prevention of these infections is based on the type-specific M protein epitopes. A multivalent M protein-based vaccine containing type-specific determinants from 26 different M serotypes is now in clinical trials. Recent epidemiologic studies have shown that, within some serotypes, the amino-terminal M protein sequence may show natural variation, giving rise to subtypes. This raises the possibility that vaccine-induced antibodies against the parent type may not be as effective in promoting bactericidal killing of variant subtypes. In the present study we used rabbit antisera against the 26-valent M protein-based vaccine in bactericidal tests against M1, M3, and M5 streptococci, which were represented by multiple subtypes. We show that the vaccine antibodies effectively promoted in vitro bactericidal activity despite the fact that the M proteins contained naturally occurring variant sequences in the regions corresponding to the vaccine sequence. Our results show that the variant M proteins generally do not result in significant differences in opsonization promoted by rabbit antisera raised against the 26-valent vaccine, suggesting that a multivalent M protein vaccine may not permit variant subtypes of group A streptococci to escape in a highly immunized population.