Tonsillolith. Case report and review of the literature.

Large oropharyngeal concretions--giant tonsillolith--are not very common. Over the last few years only some 50 cases have been reported in the literature. Many tonsilloliths, especially small concretions, are asymptomatic; large concretions, on the contrary, may produce several symptoms. The case is described of a 56-year-old female complaining of dysphagia, odynophagia, sore throat, right otalgia and swelling in right tonsillar fossa. Routine panoramic radiography revealed a radio-opaque area in right tonsil region. Computed tomography of oropharynx was performed and axial slices revealed a calcified cylindrical lesion in posterior pharyngeal region, between palatoglossus and palatopharyngeus muscles. The tonsillolith was easily excised under local anaesthesia. The post-operative course was good with no recurrence. Microscopic examination of the specimen revealed necrotic debris, "ghost" cells, calcifications and inflammatory cells, confirming the diagnosis of tonsillolith. Authors stress that large tonsillar concretions are uncommon, and may be difficult to diagnose since the tonsillolith can also be mistaken for other anatomic and pathologic structures in the oropharyngeal area.

Increased cellular fatty acid desaturation as a possible key factor in thermotolerance in Saccharomyces cerevisiae.

An increase of the unsaturation level of the cellular fatty acids was observed at sublethal or superoptimal temperatures in Saccharomyces cerevisiae. The hypothesis of this paper is that a high unsaturated fatty acids relative content "per se" is not a prerequisite for withstanding sublethal temperature stress in yeast but is the result of oxygen-consuming desaturase activation, with consequent reduction of oxygen and the oxygen free radicals as they form during thermal stress. In the thermotolerant strains, no increase of cellular thiobarbituric acid reactive substances (TBARSs) was observed when temperature approached the maximal growth temperature, suggesting prevention of oxidative damage. On the other hand, the values of TBARSs tripled at 42 degrees C in nonthermotolerant strains. When a sublethal hydrogen peroxide treatment preceded a rapid temperature rise, a selected thermotolerant strain responded with a relative increase of saturated fatty acids. This response, associated with an insignificant viability loss due to the double stress, suggests the induction an alternative oxygen consumption mechanism preventing excessive fatty acid unsaturation, which could be detrimental to the cells in the presence of hydrogen peroxide at sublethal temperatures.