Public Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke.

Tobacco use and tobacco smoke exposure are among the most important health threats to children, adolescents, and adults. There is no safe level of tobacco smoke exposure. The developing brains of children and adolescents are particularly vulnerable to the development of tobacco and nicotine dependence. Tobacco is unique among consumer products in that it causes disease and death when used exactly as intended. Tobacco continues to be heavily promoted to children and young adults. Flavored and alternative tobacco products, including little cigars, chewing tobacco, and electronic nicotine delivery systems are gaining popularity among youth. This statement describes important evidence-based public policy actions that, when implemented, will reduce tobacco product use and tobacco smoke exposure among youth and, by doing so, improve the health of children and young adults.

Clinical Practice Policy to Protect Children From Tobacco, Nicotine, and Tobacco Smoke.

Tobacco dependence starts in childhood. Tobacco exposure of children is common and causes illness and premature death in children and adults, with adverse effects starting in the womb. There is no safe level of tobacco smoke exposure. Pediatricians should screen for use of tobacco and other nicotine delivery devices and provide anticipatory guidance to prevent smoking initiation and reduce tobacco smoke exposure. Pediatricians need to be aware of the different nicotine delivery systems marketed and available.Parents and caregivers are important sources of children's tobacco smoke exposure. Because tobacco dependence is a severe addiction, to protect children's health, caregiver tobacco dependence treatment should be offered or referral for treatment should be provided (such as referral to the national smoker's quitline at 1-800-QUIT-NOW). If the source of tobacco exposure cannot be eliminated, counseling about reducing exposure to children should be provided.Health care delivery systems should facilitate the effective prevention, identification, and treatment of tobacco dependence in children and adolescents, their parents, and other caregivers. Health care facilities should protect children from tobacco smoke exposure and tobacco promotion. Tobacco dependence prevention and treatment should be part of medical education, with knowledge assessed as part of board certification examinations.

Primary care physician smoking screening and counseling for patients with chronic disease.

BACKGROUND: Evidence-based guidelines recommend smoking cessation treatment, including screening and counseling, for all smokers, including those with chronic diseases exacerbated by smoking. Physician treatment improves smoking cessation. Little data describes smoking treatment guideline uptake for patients with chronic cardiopulmonary smoking-sensitive diseases. OBJECTIVE: Describe U.S. primary care physician (PCP) smoking cessation treatment during patient visits for chronic cardiopulmonary smoking-sensitive diseases. METHODS: The National (Hospital) Ambulatory Medical Care Survey captured PCP visits. We examined smoking screening and counseling time trends for smokers with chronic diseases. Multivariable logistic regression assessed factors associated with smoking counseling for smokers with chronic smoking-sensitive diseases. RESULTS: From 2001-2009 smoking screening and counseling for smokers with chronic smoking-sensitive cardiopulmonary diseases were unchanged. Among smokers with chronic smoking-sensitive diseases, 50%-72% received no counseling. Smokers with chronic obstructive pulmonary disease (COPD) (odds ratio (OR)=6.54, 95% confidence interval (CI) 4.85-8.83) and peripheral vascular disease (OR=4.50, 95% CI 1.72-11.75) were more likely to receive smoking counseling at chronic/preventive care visits, compared with patients without smoking-sensitive diseases. Other factors associated with increased smoking counseling included non-private insurance, preventive and longer visits, and an established PCP. Asthma and cardiovascular disease showed no association with counseling. CONCLUSIONS: Smoking cessation counseling remains infrequent for smokers with chronic smoking-sensitive cardiopulmonary diseases. New strategies are needed to encourage smoking cessation counseling.

The importance of peripheral sequences in determining the metal selectivity of an in vitro-selected Co(2+) -dependent DNAzyme.

DNAzymes are catalytically active DNA molecules that use metal cofactors for their enzymatic functions. While a growing number of DNAzymes with diverse functions and metal selectivities have been reported, the relationships between metal ion selectivity, conserved sequences and structures responsible for selectivity remain to be elucidated. To address this issue, we report biochemical assays of a family of previously reported in vitro selected DNAzymes. This family includes the clone 11 DNAzyme, which was isolated by positive and negative selection, and the clone 18 DNAzyme, which was isolated by positive selection alone. The clone 11 DNAzyme has a higher selectivity for Co(2+) over Pb(2+) compared with clone 18. The reasons for this difference are explored here through phylogenetic comparison, mutational analysis and stepwise truncation. A novel DNAzyme truncation method incorporated a nick in the middle of the DNAzyme to allow for truncation close to the nicked site while preserving peripheral sequences at both ends of the DNAzyme. The results demonstrate that peripheral sequences within the substrate binding arms, most notably the stem loop, loop II, are sufficient to restore its selectivity for Co(2+) over Pb(2+) to levels observed in clone 11. A comparison of these sequences' secondary structures and Co(2+) selectivities suggested that metastable structures affect metal ion selectivity. The Co(2+) selectivity of the clone 11 DNAzyme showed that the metal ion binding and selectivities of small, in vitro selected DNAzymes may be more complex than previously appreciated, and that clone 11 may be more similar to larger ribozymes than to other small DNAzymes in its structural complexity and behavior. These factors should be taken into account when metal-ion selectivity is required in rationally designed DNAzymes and DNAzyme-based biosensors.

The prebiotic synthesis of pyrimidines in frozen solution.

Most prebiotic syntheses depend on the reaction of concentrated precursor compounds to produce bio-organic molecules. It is now believed that the early Earth's atmosphere was not reducing enough to have permitted copious synthesis of precursor molecules. Freezing allows reaction to occur even from dilute solution. This reaction has been demonstrated for the purines but not for the pyrimidines. It is shown here that dilute solutions of simple prebiotic molecules produce the biological pyrimidines cytosine and uracil upon freezing. Cold environments may have allowed synthesis of all of the RNA bases even from low organic yielding atmospheres, such as those of the early Earth, Mars, Titan and Europa.

In vitro selection of high temperature Zn(2+)-dependent DNAzymes.

In vitro selection of Zn(2+)-dependent RNA-cleaving DNAzymes with activity at 90 degrees C has yielded a diverse spool of selected sequences. The RNA cleavage efficiency was found in all cases to be specific for Zn(2+) over Pb(2+), Ca(2+), Cd(2+), Co(2+), Hg(2+), and Mg(2+). The Zn(2+)-dependent activity assay of the most active sequence showed that the DNAzyme possesses an apparent Zn(2+)-binding dissociation constant of 234 muM and that its activity increases with increasing temperatures from 50-90 degrees C. A fit of the Arrhenius plot data gave E(a) = 15.3 kcal mol(-1). Surprisingly, the selected Zn(2+)-dependent DNAzymes showed only a modest (approximately 3-fold) activity enhancement over the background rate of cleavage of random sequences containing a single embedded ribonucleotide within an otherwise DNA oligonucleotide. The result is attributable to the ability of DNA to sustain cleavage activity at high temperature with minimal secondary structure when Zn(2+) is present. Since this effect is highly specific for Zn(2+), this metal ion may play a special role in molecular evolution of nucleic acids at high temperature.