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Biomedical subjects

L Silvestri

Publications and source records attributed to L Silvestri.

9 recordsLinked to original sources
PubMed1992

Mixed microprocessor-random logic approach for innovative pacing systems.

Modern pacing systems are becoming more and more sophisticated. Conversion of the information supplied by a sensor into suitable parameters for a rate controlling algorithm and the management of complex timing are common tasks for an integrated circuit (IC) in cardiac pacing. An effective solution consists of using a microprocessor to implement algorithms and pacing modes in a flexible way. The key point of using the same hardware resources for different tasks on a time sharing basis allows the design of a less complex IC when compared to a random logic structure with the same performances. The major design problems in a full microprocessor solution are its relatively low operating speed due to the low frequency clock necessary for low current drain, and the sequential structure of the machine itself. This can lead to unacceptable timing inaccuracy in all situations requiring the management of complex decision trees. In order to take full benefit from the advantages of a microprocessor structure without these drawbacks, a mixed microprocessor-random logic approach has been investigated. This architecture uses a microprocessor core to perform all high level nonreal-time operations (setup of the pacing cycle, data reduction and processing, data integrity checks) while a set of random logic peripherals is used for all critical timing aspects.

Algorithms↗
PubMed1992

[Results of audiometric and vestibular tests in Cogan syndrome: apropos of a case].

The authors report on a case of Cogan's syndrome pointing out that hearing loss is due both to cochlear lesions from likely immunitary origin as well as to widespread alterations of auditory central nervous structures. This interpretation allows to explain the apparent discrepancy of the found clinical and instrumental data. From a therapeutic point of view, the authors assert the necessity of an early corticosteroid therapy to obtain some appreciable result. Anyway, they point out how prognosis for auditory function in Cogan's syndrome is often very poor.

Adult↗
PubMed1988

The collaborative study of the international standard of dog, Canis domesticus, hair/dander extract.

A collaborative study was carried out to assess the suitability of a chosen preparation to serve as the international standard (IS) for dog (Canis domesticus) hair/dander extract. Sets of five coded preparations of dog extract, including the proposed IS, were delivered to each participating laboratory in glass-sealed ampules. Fifteen laboratories in nine different countries examined the preparations by RAST inhibition, crossed immunoelectrophoresis/crossed radioimmunoelectrophoresis, histamine release, and by other methods. In spite of the use of different versions of methods and different reagents, quite consistent results were obtained, and the proposed IS was found to have a satisfactory activity in all assays and to be useful as a calibrator when allergenic potency of similar dog allergenic extracts was estimated. Four laboratories estimated the specific content of allergens Ag 3, Ag 13, and albumin and found the proposed IS to be a suitable standard for these assays. On the basis of the results from this study, the World Health Organization established the preparation as the international standard for dog hair/dander extract with an assigned unitage of 100,000 IU per ampule. The units refer to both the total allergenic activity of the ampule and to that of individual allergens.

Allergens↗
PubMed1988

Adriamycin-plasma membrane interaction in human erythrocytes.

A great body of data increasingly point to the cell membrane as an important target for adriamycin (ADR). However, the exact mechanism by which ADR exerts its cytotoxic action through the interaction with the plasma membrane is still unknown. In this study, the interaction of ADR with red blood cells from healthy donors was investigated by freeze-fracturing (FF) and scanning electron microscopy (SEM). The results obtained can be summarized as follows: a) a dose-dependent modification in the intramembrane particle (IMP) distribution was revealed by FF on both fracture faces of the plasma membrane of erythrocytes treated with 50 or 100 microM ADR; b) SEM observations allowed to reveal a discocyte-stomatocyte transition induced by 50 microM ADR and the formation of mottled cells at the higher dose; c) these morphological and ultrastructural changes were not related to lipid peroxidation as demonstrated by experiments with radical scavengers or strong oxidant substances; d) the analysis of IMP density seemed to rule out a segregation process of membrane proteins suggesting that ADR interacts with the plasma membrane by becoming incorporated within the lipid bilayer.

Doxorubicin↗
PubMed1987

The safety and activity of polymerized ragweed: a double-blind, placebo-controlled trial in 81 patients with ragweed rhinitis.

Eighty-one patients with ragweed pollinosis were recruited for a double-blind, histamine placebo-controlled study of the safety, immunogenicity, and efficacy of 15 weekly injections of polymerized ragweed (PRW) immunotherapy totaling 1359 allergy units. Patients were paired on the basis of cutaneous end point titration to RAST standardized extracts of giant and short ragweed. One patient of each pair was randomized to receive PRW, and the other patient, a caramelized glucose histamine placebo. Symptom and medication score diaries were completed by 68 patients. All 68 patients received the full maintenance dose. No patient dropped out because of adverse reactions, and there were no systemic reactions. Except for one patient receiving placebo who developed mildly elevated liver function tests, there were no clinically significant changes in routine laboratory tests associated with injections. By Student's test on log-transformed values, blocking antibody rose significantly in the patients receiving PRW but was unchanged in those receiving placebo. By Wilcoxon paired signed-rank test, the symptom and medication scores in the patients receiving PRW were significantly lower than scores in the patients receiving placebo. This study demonstrates the safety, immunogenicity, and activity of PRW in the treatment of ragweed pollinosis.

Adult↗
PubMed1979

[Malignant hyperthermia. Review of literature and case reports].

Malignant hyperthermia may appear during surgery. It has at least three features: 1) an anesthesiological trigger, usually the association of halothane and succinylcholine; 2) rapid increase in body temperature; 3) widespread muscle hypertonia. The literature is reviewed in an assessment of the physiopathological mechanism underlying the syndrome, with particular reference to the part played by calcium. Experimental data are cited and their similarity with the clinical, laboratory, anatomical, and histopathological picture in man is discussed. A detailed account is also given of two personal cases. Lastly, questions associated with the prevention and treatment of malignant hyperthermia are examined.

Acid-Base Equilibrium↗