Mechanistic Insights into Oxidative Oligomerization of p-Phenylenediamine and Resorcinol.

An efficient synthesis of a green dye from oxidative coupling of p-phenylenediamine (PPD) and resorcinol (in a 2:1 ratio) has been developed. Reactivity studies of this dye molecule with a variety of reagents (PPD, resorcinol, the oxidized form of the green dye itself, and a dinuclear indo dye) demonstrate that it cannot be the key reactive intermediate in reported oxidative oligomerization of PPD and resorcinol. However, the trinuclear species does form large aggregates. At least one viable pathway of oligomerization has been demonstrated with the dinuclear indo dye.

Comparison of damage to human hair fibers caused by monoethanolamine- and ammonia-based hair colorants.

The number of Level 3 hair color products that substitute 2-aminoethanol [monoethanolamine (MEA)] for ammonia is increasing. There is some anecdotal evidence that higher levels of MEA can be more damaging to hair and more irritating than a corresponding equivalent level of the typical alkalizer, ammonia (in the form of ammonium hydroxide). Our interest was to understand in more quantitative terms the relative hair damage from the two alkalizers, particularly at the upper limits of MEA on-head use. Limiting investigations of oxidative hair damage to increases in cysteic acid content (from cystine oxidation) can underreport the extent of total damage. Hence, we complemented Fourier transform infrared spectroscopy (FTIR) cysteic acid level measurement with scanning electron microscopy (SEM) photomicrographs to visualize cuticle damage, and protein loss to understand not only the oxidative damage but also the damage caused by other damage pathways, e.g., reaction of the more nucleophilic (than ammonia) MEA with hair protein. In fact, all methods show an increase in damage from MEA-based formulations, up to 85% versus ammonia in the most extreme case. Hence, if the odor of ammonia is a concern, a better approach may be to minimize the volatility of ammonia in specific chassis rather than replacing it with high levels of a potentially more damaging alkalizer such as MEA.

Ciprofloxacin-induced phototoxicity in an adult cystic fibrosis population.

The incidence of phototoxicity as a side effect of ciprofloxacin appears to be increased in patients with cystic fibrosis compared to the general population (approximately 2.4%). We used an interview-based questionnaire to determine the incidence of such phototoxic skin reactions in cystic fibrosis patients. Results from 105 respondents revealed the incidence of ciprofloxacin-induced phototoxicity in the adult cystic fibrosis population in Northern Ireland to be 48.4% with only 66% of the patients recalling being given sun care information beforehand. We concluded that the incidence of phototoxicity is increased in patients with cystic fibrosis and that it is important for all to receive good sun care information prior to taking ciprofloxacin given the high risk of developing phototoxic rash.