In this study, despite an 18-month intervention, time from symptom onset to hospital arrival for patients with chest pain did not change differentially between groups, although increased appropriate EMS use occurred in intervention communities. New strategies are needed if delay time from symptom onset to hospital presentation is to be decreased further in patients with suspected AMI. JAMA. 2000;284:60-67

Easily processed materials with the ability to transport excitons over length scales of more than 100 nanometers are highly desirable for a range of light-harvesting and optoelectronic devices. We describe the preparation of organic semiconducting nanofibers comprising a crystalline poly(di-n-hexylfluorene) core and a solvated, segmented corona consisting of polyethylene glycol in the center and polythiophene at the ends. These nanofibers exhibit exciton transfer from the core to the lower-energy polythiophene coronas in the end blocks, which occurs in the direction of the interchain p-p stacking with very long diffusion lengths (>200 nanometers) and a large diffusion coefficient (0.5 square centimeters per second). This is made possible by the uniform exciton energetic landscape created by the well-ordered, crystalline nanofiber core.

OBJECTIVES. Project Northland is an efficacy trial with the goal of preventing or reducing alcohol use among young adolescents by using a multilevel, communitywide approach. METHODS. Conducted in 24 school districts and adjacent communities in northeastern Minnesota since 1991, the intervention targets the class of 1998 (sixth-grade students in 1991) and has been implemented for 3 school years (1991 to 1994). The intervention consists of social-behavioral curricula in schools, peer leadership, parental involvement/education, and communitywide task force activities. Annual surveys of the class of 1998 measure alcohol use, tobacco use, and psychosocial factors. RESULTS. At the end of 3 years, students in the intervention school districts report less onset and prevalence of alcohol use than students in the reference districts. The differences were particularly notable among those who were nonusers at baseline. CONCLUSIONS. The results of Project Northland suggest that multilevel, targeted prevention programs for young adolescents are effective in reducing alcohol use.

No abstract

OBJECTIVES. The Minnesota Heart Health Program is a 13-year research and demonstration project to reduce morbidity and mortality from coronary heart disease in whole communities. METHODS. Three pairs of communities were matched on size and type; each pair had one education site and one comparison site. After baseline surveys, a 5- to 6-year program of mass media, community organization, and direct education for risk reduction was begun in the education communities, whereas surveys continued in all sites. RESULTS. Many intervention components proved effective in targeted groups. However, against a background of strong secular trends of increasing health promotion and declining risk factors, the overall program effects were modest in size and duration and generally within chance levels. CONCLUSIONS. These findings suggest that even such an intense program may not be able to generate enough additional exposure to risk reduction messages and activities in a large enough fraction of the population to accelerate the remarkably favorable secular trends in health promotion activities and in most coronary heart disease risk factors present in the study communities.

No abstract

Fiber-like block copolymer (BCP) micelles offer considerable potential for a variety of applications, however, uniform samples of controlled length and with spatially tailored chemistry have not been accessible. Recently, a seeded growth method, termed 'living' crystallization-driven self-assembly (CDSA), has been developed to allow the formation of 1D micelles and block comicelles of precisely controlled dimensions from BCPs with a crystallizable segment. An expansion of the range of core forming blocks that participate in living CDSA is necessary for this technique to be compatible with a broad range of applications. Few examples currently exist of well-defined, water-dispersible BCP micelles prepared using this approach, especially from biocompatible and biodegradable polymers. Herein, we demonstrate that BCPs containing a crystallizable polycarbonate, poly(spiro[fluorene-9,5'-[1,3]dioxin]-2'-one) (PFTMC), can readily undergo living CDSA processes. PFTMC-b-poly(ethylene glycol) (PEG) BCPs with PFTMC:PEG block ratios of 1:11 and 1:25 were shown to undergo living CDSA to form near monodisperse fiber like micelles of precisely controlled lengths of up to ~1.6 m. Detailed structural characterization of these micelles by TEM, AFM, SAXS and WAXS, revealed that they comprise a crystalline, chain folded PFTMC core with a rectangular cross-section that is surrounded by a solvent swollen PEG corona. PFTMC-b-PEG fiber-like micelles were shown to be dispersible in water to give colloidally stable solutions. This allowed an assessment of the toxicity of these structures towards WI-38 and HeLa cells. From these experiments, we observed no discernable cytotoxicity from a sample of 119 nm fiber-like micelles to either the healthy (WI-38) or cancerous (HeLa) cell types. The living CDSA process was extended to PFTMC-b-poly(2-vinylpyridine) (P2VP), and addition of this BCP to PFTMC-b-PEG seed micelles led to the formation of well-defined segmented fibers with spatially localized coronal chemistries.

The solution-phase self-assembly or “polymerization” of discrete colloidal building blocks, such as “patchy” nanoparticles and multicompartment micelles, is attracting growing attention with respect to the creation of complex hierarchical materials.