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Biomedical subjects

G Guzzi

Publications and source records attributed to G Guzzi.

12 recordsLinked to original sources
PubMed2006

Determination of dose rates from natural radionuclides in dental materials.

Different types of materials used for dental prosthetics restoration, including feldspathic ceramics, glass ceramics, zirconia-based ceramics, alumina-based ceramics, and resin-based materials, were investigated with regard to content of natural radionuclides by means of thermoluminescence beta dosimetry and gamma spectrometry. The gross beta dose rate from feldspathic and glass ceramics was about ten times higher than the background measurement, whereas resin-based materials generated negligible beta dose rate, similarly to natural tooth samples. The specific activity of uranium and thorium was significantly below the levels found in the period when addition of uranium to dental porcelain materials was still permitted. The high-beta dose levels observed in feldspathic porcelains and glass ceramics are thus mainly ascribable to (40)K, naturally present in these specimens. Although the measured values are below the recommended limits, results indicate that patients with prostheses are subject to higher dose levels than other members of the population. Alumina- and zirconia-based ceramics might be a promising alternative, as they have generally lower beta dose rates than the conventional porcelain materials. However, the dosimetry results, which imply the presence of inhomogeneously distributed clusters of radionuclides in the sample matrix, and the still unsuitable structural properties call for further optimization of these materials.

Ceramics↗
PubMed1995

Molecular typing of Candida albicans in oral candidiasis: karyotype epidemiology with human immunodeficiency virus-seropositive patients in comparison with that with healthy carriers.

Candida albicans organisms isolated from the oral cavities of healthy carriers (26 individuals) and compromised hosts (40 human immunodeficiency virus [HIV]-seropositive patients, all showing symptomatic oral candidiasis) were compared by resolving chromosome-sized DNA molecules into electrophoretic karyotypes. Seven- to 10-band electrophoretic patterns were obtained, with significant and reproducible differences in the distributions of the DNA bands. Seven distinct classes were identified and were designated type a (8 bands), type b (8 bands), type c (7 bands), type d (9 bands), type x (10 bands), type y (10 bands), and type z (9 bands). Four of these (types a to d) were the most representative within all of the isolated strains (95.5%), and the other three (types x to z) were observed only once in three HIV-seropositive individuals (4.5%). Only types b and c were isolated from healthy carriers, with the percentage of their isolation being 61.5 and 38.5%, respectively, while all the described karyotypes were isolated from HIV-seropositive patients, with type b being the most frequent (45%); this was followed by types c (25%), a (15%), and d (7.5%). The prevalence of type b and c karyotypes in HIV-infected individuals, as well as in healthy carriers, suggests that commensal strains in the oral cavities of healthy individuals may become the prevalent agents of subsequent oral candidiasis in compromised hosts. However, replacement of the original, commensal strain, if there is one, cannot be excluded in a compromised host, although strain replacement may be more reasonably hypothesized for types a and d, since only these types were isolated at a relative high percentage from the oral lesions of HIV-infected individuals.

AIDS-Related Opportunistic Infections↗
PubMed1993

Emergency surgical treatment of ruptured incompetent mitral valve after percutaneous valvuloplasty.

Of 263 consecutive patients undergoing mitral balloon valvulotomy at the Cardiac Catheterization Unit of Padua University Hospital, six (2.3%) required surgical treatment within 24 hours. The indication for surgery was unstable hemodynamic status due to acute mitral insufficiency caused by the percutaneous balloon valvulotomy. The purpose of this study was to evaluate whether the failure of percutaneous mitral balloon valvulotomy, in this subset of patients, was related to technical problems or was the direct consequence of unfavourable pathologic conditions. Additionally, we evaluated the operative results and clinical outcome of these six patients. The patients were all female with a mean age of 55.7 +/- 14 years (range 38-75 years). Previous surgical commissurotomy was performed in three. The anatomical lesions responsible for the massive regurgitation were tear of the anterior leaflet in two patients and tear of the posterior leaflet in four; rupture of the papillary muscle and/or chordae tendineae were present in five. All patients underwent mitral valve replacement. The elapsed time between the onset of mitral regurgitation and surgery ranged from two to 24 hours (mean 10 +/- 11 hours). There were two hospital deaths (33.3 +/- 21.1%): all surviving patients are alive and clinically well. In conclusion, massive mitral regurgitation following percutaneous mitral dilatation appears to be related to unfavourable pathology of the mitral valve rather than to technical errors. Therefore, careful patient selection is mandatory in order to achieve optimal results. In our experience, adequate and aggressive medical therapy provided sufficient time to prepare for the surgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗