[Esthesioneuroblastoma. Description of a case and review of the literature]. / Estesioneuroblastoma. Presentación de un caso clínico y revisión de la bibliografía.

The esthesioneuroblastoma is a malignant and rare type of the nasal cavity. Affected patients usually present with a progressive nasal obstruction, rhinorrea and epistaxis. Metastasis occurs in about 30% of patiens, the most common sites for metastasis are the cervical lymph nodes, less frequent in anothers organs. The optimum management is probably surgery combined with radiotherapy, the chemotherapy is usually reserved for local advanced tumor

[Intra-laryngeal ectopic thyroid tissue. Report of one case and review of the literature]. / Tejido tiroideo ectópico intralaríngeo. Presentación de un caso clínico y revisión de la literatura.

A Ectopic thyroid is any thyroid tissue not located in his normal anatomic situation. There have been described four general groups within the upper aerodigestive tract: lingual, sublingual, thyroglossal and intralaryngotracheal. Intralaryngotracheal thyroid tissue is rare and constitute 7 per cent of all intratracheal tumours, and it represents a problem of diagnosis and management. The controversy about the genesis of this tumours remains. There are two established theories: "the malformation theory" and "the ingrowth theory". These tumours affect more frequently adult female. Intralaryngotracheal thyroid have been mainly reported on the posterior-left wall of the trachea. The most common clinical feature is stridor due to progressive upper airway obstruction. Up to 75% of the intralaryngotracheal goiters are associated with and external goiter. This paper reports a case of ectopic subglotic thyroid in a 42 year-old-female. The embryology, diagnosis and management of this tumours are discussed.

Kinetics of the lipase-catalyzed synthesis of glucose esters in acetone.

A simple kinetic model derived from a ping-pong bi-bi mechanism is proposed to describe the lipase-catalyzed esterification of glucose with fatty acids. The mathematical expressions derived from this model have been tested using several sets of data obtained from reactions carried out under different reaction conditions. The predicted values provide very good fits of the experimental data for temperatures from 30 to 60 degrees C, enzyme loadings from 90 to 180 mg, and fatty acid concentrations from 0.33M to 1M. Experiments conducted at different temperatures permit one to estimate an activation energy of approximately 12 kcal/mol for the rate-limiting step of the reaction (formation of the acyl-enzyme complex). The model also considers the kinetics of inactivation of the biocatalyst during the reaction.

Synthesis of glycerides containing n-3 fatty acids and conjugated linoleic acid by solvent-free acidolysis of fish oil.

Menhaden oil, a rich source of n-3 fatty acids, was interesterified with conjugated linoleic acid (CLA) in a reaction medium composed solely of substrates and either free or immobilized commercial lipase preparations. Of five lipases tested, an immobilized preparation from Mucor miehei provided the fastest rate of incorporation of CLA into fish oil acylglycerols; however, and as observed with most of the lipases utilized, a significant proportion of the n-3 fatty acid residues were liberated in the process. A soluble lipase from Candida rugosa converted free CLA to acylglycerol residues while leaving the n-3 fatty acid residues virtually untouched. Even though the reaction rate was slower for this enzyme than for the other four lipase preparations, the specificity of the free C. rugosa lipase gives it the greatest potential for commercial use in preparing fish oils enriched in CLA residues but still retaining their original n-3 fatty acid residues.

Continuous enzymatic esterification of glycerol with (poly)unsaturated fatty acids in a packed-bed reactor.

Enzymatic synthesis of mono-, di-, and triacyglycerols from (poly)unsaturated fatty acids (linoleic, oleic, and conjugated linoleic acids) has been studied as a solvent-free reaction in a packed-bed reactor containing an immobilized lipase from Mucor miehei. The extents of the esterification reactions of interest are primarily determined by the molar ratio of glycerol to fatty acid because the presence of excess glycerol as a immiscible phase is responsible for reducing the activity of the water produced by the esterification reactions. For molar ratios of fatty acid to glycerol of less than 1.5, the percentage of the fatty acid esterified decreases quasi-linearly with an increase in this molar ratio. By appropriate manipulation of the fluid-residence time, one can control the relative proportions of the various acylglycerols in the effluent stream. At the outlet of the reactor, one observes excellent spontaneous separation of the glycerol and acylglycerol/fatty acid phases. At 50 degrees C and a fluid residence time of 1 hour, as much as 90% of the fatty acid can be esterified when the molar ratio of fatty acid to glycerol is 0.33 or less.

[Small-cell carcinoma of the larynx]. / Carcinoma de células pequeñas de laringe.

Primary small-cell (also known as oat-cell) neuroendocrine carcinoma of the larynx is an infrequent tumor. We report a case of epiglottic oat-cell carcinoma in a 57-year-old man. Its association with other malignant neoplasms and aggressive behavior in spite of treatment are discussed.

Interesterification (acidolysis) of butterfat with conjugated linoleic acid in a batch reactor.

Six commercial lipases, in free or immobilized form, were tested for their ability to catalyze acyl exchange between conjugated linoleic acid and anhydrous butterfat under solvent-free conditions. Immobilized Candida antarctica lipase exhibited the best activity. Experiments were conducted for this lipase in butterfat to conjugated linoleic acid ratios of 10:1 (vol/vol), temperatures from 30 to 70 degrees C, enzyme concentrations of 50 to 200 mg/g of reaction mixture, and water contents of 0.15 to 2% (wt/wt). At the maximum enzyme concentration used, equilibrium was reached within the first 24 h of reaction. The optimum temperature was 50 degrees C. The triacylglycerol profile of the product butterfat reflected changes in the relative proportions of fatty acid residues as the reaction proceeded, with increases in those triacylglycerols containing 46 to 54 carbon atoms and concomitant decreases in those triacylglycerols containing 34 to 42 carbon atoms.

[The sensorineural component of hearing loss associated with cholesteatoma]. / El componente neurosensorial de la hipoacusia asociada al colesteatoma.

Patients with cholesteatoma often suffer neurosensorial hearing loss with variable bone conduction thresholds. Its origin is debated and has been attributed to the ototoxicity of topical drugs, immune reactions, effects of ototoxic antibiotics applied to the ear, etc. A selected series of 50 patients who underwent surgery for chronic ear disease due to cholesteatoma in our ENT department were studied to evaluate the possible origin of the bone conduction component of hearing loss. Different clinical, audiological, and surgical aspects were analyzed, including cholesteatoma site and extension, age, sex, evolution of the symptoms, pure tone audiometry data, middle ear involvement, the operation performed, and the occurrence of complications. Bone conduction thresholds were reported as pure tone differential thresholds (affected vs non-affected ear). A specific cholesteatoma-related neurosensorial hearing loss was observed that might lead to irreversible hearing loss. Neurosensorial involvement seems to be related mainly to the duration of symptoms, type of surgery, certain specific clinical aspects, and complications.