Enhancement of orimulsion biodegradation through the addition of natural marine carbon substrates.

Orimulsion is a bitumen-based heavy fuel that is a less expensive alternative to traditional fuel oils. However, because its density is intermediate between that of freshwater and seawater, in the event of a spill, the fuel could strand in the sediments. Previous work indicated that only 0.6-2.7% of the bitumen would degrade in long incubations of marine sediments. We added various natural carbon substrates to stimulate the degradation of bitumen by native populations of benthic bacteria. The concentration and carbon isotopic signature of the respired carbon dioxide was measured to partition the substrates that supported bacterial respiration. We found that the addition of seagrass and pinfish stimulated the degradation of bitumen by as much as 2-9-fold relative to incubations without these substrates. Biodegradation of bitumen may be enhanced by the addition of natural marine carbon substrates and may be a useful approach for bioremediation. Preadaptation of the bacteria to bitumen did not significantly enhance their ability to degrade it.

[Preventive action on stable exercise-induced angina of a topical nitroglycerin gel and of an oral slow-release nitroglycerin compound (Lénitral) in low and high dosage (author's transl)]. / Action préventive dans l'angor d'effort stable, d'un gel de trinitrine à absorption cutanée et de doses faibles et fortes de trinitrine à libération intestinale progressive (Lénitral).

A nitroglycerin gel applied to the skin in doses of 15 to 30 mg prevents or delays the anginal pain induced by an excise tolerance test. The effects of the drug after a single application lasted 3 hours irrespective of the dose. Improvement in terms of increased heart rate, decreased S-T segment displacement and increased exercise capacity was the same as that observed after 0,75 mg sublingual nitroglycerin. A single 2.5 mg dose of an oral compound slowly released from the intestine (Lénitral) had no measurable effect during a 3-hour observation period. In contrast, a single 7.5 mg dose of the same compound produced, after 3 hours, the same overall improvement as that obtained with 0.75 mg sublingual nitroglycerin.