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The effect of increasing water composition on the rheological and microstructural behavior of a ternary cellulose acetate (CA)/N,N-dimethylacetamide (DMA)/water system is examined. Addition of water to the CA/DMA system results in enhanced steady shear viscosity and dynamic viscoelastic properties and ultimately to phase-separated gel formation. The changes in dynamic rheological behavior of the system during gelation correlate well with the combined solubility parameter (delta) and, in particular, the Hansen hydrogen-bonding solubility parameter index (delta(h)) of the solvent system, suggesting hydrogen-bonding interactions may be the major route initiating the sol-gel process. For all gels studied, the elastic modulus and the critical stress to yield shifts to higher values with increasing CA concentration and/or water content. In addition, the elastic modulus exhibits a power-law behavior with water content, with the same power-law exponent observed for gels containing different CA concentrations. Addition of water leads to formation of a denser gel network, as evidenced from direct visualization of the gel microstructure through confocal microscopy.

A randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate the ability of Echinacea purpurea to prevent infection with rhinovirus type 39 (RV-39). Forty-eight previously healthy adults received echinacea or placebo, 2.5 mL 3 times per day, for 7 days before and 7 days after intranasal inoculation with RV-39. Symptoms were assessed to evaluate clinical illness. Viral culture and serologic studies were performed to evaluate the presence of rhinovirus infection. A total of 92% of echinacea recipients and 95% of placebo recipients were infected. Colds developed in 58% of echinacea recipients and 82% of placebo recipients (P=.114, by Fisher's exact test). Administration of echinacea before and after exposure to rhinovirus did not decrease the rate of infection; however, because of the small sample size, statistical hypothesis testing had relatively poor power to detect statistically significant differences in the frequency and severity of illness.

No abstract

Adapalene 0.1% gel (Differin gel) is a recently introduced topical treatment for mild to moderate acne which has been demonstrated to be much better tolerated and at least as effective as tretinoin 0.025% gel. We compared the tolerance of adapalene 0.1% gel with six different formulations and concentrations of tretinoin. A total of 55 healthy human subjects were enrolled in two controlled, randomized, observer blinded, intraindividual comparison studies. In the first study, adapalene 0.1% gel was evaluated for its 21-day cumulative irritation potential compared with tretinoin 0.025%, 0.05% and 0.1% cream, tretinoin 0.01% and 0.025% gel, and petrolatum (control). In the second study, adapalene 0.1% gel was evaluated for its 21-day cumulative irritation potential compared with tretinoin 0.025%, 0.05% and 0.1% cream, tretinoin 0.1% gel microsphere, and petrolatum (control). In both studies, cumulative irritation scores helped to define three groups of common irritancy potential, with significant differences between each group. In study A, the three groups were in descending order of irritancy: tretinoin 0.1% cream and tretinoin 0.05% cream; tretinoin 0.025% gel, tretinoin 0.01% gel and tretinoin 0.025% cream; adapalene 0.1% gel and petrolatum (control). In study B, the three groups were in descending order of irritancy: tretinoin 0.1% cream; tretinoin 0.05% cream, tretinoin 0.025% cream and tretinoin 0.1% gel microsphere; adapalene 0.1% gel and petrolatum (control). The experimental results show that adapalene 0.1% gel is significantly better tolerated than any of six formulations of tretinoin, including two gels, three creams and a microsphere formulation, ranging in potency from 0.01% to 0.1%.