Comparisons between conventional, ultrasound-assisted and microwave-assisted methods for extraction of anthraquinones from Heterophyllaea pustulata Hook f. (Rubiaceae).

This work reports a comparative study about extraction methods used to obtain anthraquinones (AQs) from stems and leaves of Heterophyllae pustulata Hook (Rubiáceae). One of the conventional procedures used to extract these metabolites from a vegetable matrix is by successive Soxhlet extractions with solvents of increasing polarity: starting with hexane to eliminate chlorophylls and fatty components, following by benzene and finally ethyl acetate. However, this technique shows a low extraction yield of total AQs, and consumes large quantities of solvent and time. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been investigated as alternative methods to extract these compounds, using the same sequence of solvents. It was found that UAE increases the extraction yield of total AQs and reduces the time and amount of solvent used. Nevertheless, the combination UAE with benzene, plus MAE with ethyl acetate at a constant power of 900 W showed the best results. A higher yield of total AQs was obtained in less time and using the same amount of solvent that UAE. The optimal conditions for this latter procedure were UAE with benzene at 50 °C during 60 min, followed by MAE at 900 W during 15 min using ethyl acetate as extraction solvent.

Multiple aphthoid syphilitic chancres of the oral cavity.

We describe the case of a 31-year-old man who was affected by three asymptomatic, aphthoid, syphilitic chancres of the oral cavity. These lesions were accompanied by right latero-cervical and chin lymphadenopathy. The infection was previously diagnosed as aphthous stomatitis. The search for Treponema pallidum by means of darkfield microscope examination was positive. The patient was successfully treated with oral erythromycin ethylsuccinate. To our knowledge, this is the first case of multiple aphthoid syphilitic chancres of the oral cavity reported in the literature. We suggest that all patients with a recent history of painless ulcers in the oral cavity, accompanied by regional lymphadenopathy in which the clinical diagnosis has not been confirmed, should undergo a darkfield microscope examination.

Cutaneous larva migrans with folliculitis: a new clinical presentation of this infestation.

Two patients (a 35-year-old woman and a 33-year-old man, just returned from trips to Jamaica and Barbados, respectively) presented with cutaneous larva migrans with folliculitis, a rare and atypical clinical presentation of this infestation. Histopathological examination revealed a follicular and perifollicular infiltrate prevalently consisting of lymphocytes and neutrophils, with numerous eosinophils. Both patients were successfully treated with oral albendazole.

An algebraic model of an associative noise-like coding memory.

A mathematical model of an associative memory is presented, sharing with the optical holography memory systems the properties which establish an analogy with biological memory. This memory system--developed from Gabor's model of memory--is based on a noise-like coding of the information by which it realizes a distributed, damage-tolerant, "equipotential" storage through simultaneous state changes of discrete substratum elements. Each two associated items being stored are coded by each other by means of two noise-like patterns obtained from them through a randomizing preprocessing. The algebraic transformations operating the information storage and retrieval are matrix-vector products involving Toeplitz type matrices. Several noise-like coded memory traces are superimposed on a common substratum without crosstalk interference; moreover, extraneous noise added to these memory traces does not injure the stored information. The main performances shown by this memory model are: i) the selective, complete recovering of stored information from incomplete keys, both mixed with extraneous information and translated from the position learnt; ii) a dynamic recollection where the information just recovered acts as a new key for a sequential retrieval process; iii) context-dependent responses. The hypothesis that the information is stored in the nervous system through a noise-like coding is suggested. The model has been simulated on a digital computer using bidimensional images.