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Biomedical subjects

A Motta

Publications and source records attributed to A Motta.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

In vivo study of polyurethane-coated Gianturco-Rosch biliary Z-stents.

PURPOSE: Prototypes of Gianturco-Rosch Z-stents coated with polycarbonate urethane (PCU) were placed in the biliary tree of pigs, in order to test their biomechanical behavior, stability, and biocompatibility. METHODS: The stents were surgically implanted in the common bile duct of three pairs of pigs, which were killed after 1, 3, and 6 months respectively. Explanted livers from pigs of the same race, age, and size were used to provide comparative data. The bile ducts were radiologically and histopathologically examined; the stents were processed and examined by scanning electron microscopy. RESULTS: No complications occurred and the animals showed a normal weight gain. The main bile duct appeared radiologically and macroscopically dilated, but the stents proved to be in place. Histologically, the bile duct epithelium was destroyed, but neither hyperplastic nor inflammatory fibrotic reactions of the wall were evident. Both the metallic structure and the polymeric coating of the stents were intact. A layer of organic material with a maximum thickness of approximately 3 micron was evident on the inner surface of the stents. CONCLUSION: The present in vivo study demonstrates the biocompatibility, efficacy, and stability of PCU-coated Gianturco-Rosch stents in the biliary environment.

Animals↗
PubMedDate not supplied

Use of a fast EM algorithm for 3D image reconstruction with the YAP-PET tomograph.

OBJECTIVE: We would like to improve the image reconstructions for both signal-to-noise ratio (SNR) and spatial resolution characteristics for the small animal positron emission tomograph YAP-PET, built at the Department of Physics of Ferrara University. The three-dimensional (3D) filtered backprojection (FBP) algorithm, usually used for image reconstruction, has a limited angle restriction due to the tomograph geometry, which causes a serious loss in sensitivity. METHODS: We implemented a 3D iterative reconstruction program using the symmetry and sparse properties of the 'probability matrix', which correlates the emission from each voxel to the detector within a coincidence tube. A fraction only of matrix elements are calculated before the reconstruction and stored on disk: this allows us to avoid on-line computation. A depth dependent function differentiates the voxels in a coincidence tube. Three experimental phantoms with no background were reconstructed by using the program, in comparison with traditionally used FBP. RESULTS: The adopted method allowed us to reduce the computation time significantly. Furthermore, the simple depth dependent function improved the spatial resolution. With 64 x 64 x 20 voxels of 0.625 x 0.625 x 2.0 mm(3) in the field of view, the computation time was less than 4 min per iteration on a Sparc Ultra 450 Workstation, and less than 6 min per iteration on a Mac-PPC G3 300 MHz: the spatial resolution measured with a 0.8 mm diameter 18F-FDG filled capillary reconstructed in this way was 2.0 mm FWHM. By decreasing the voxel size to 0.3125 x 0.3125 x 2.0 mm(3) per voxel the transaxial FWHM was 1.7 mm with a computation time of 15 min per iteration on a Sparc Ultra 450. By using all the acquired data, the SNR improves from 1.3 to 6.0 in the worst measured case, a pair of 0.8mm diameter 18F-FDG filled capillaries, which are 2.5 mm apart each other. CONCLUSION: The adoption of iterative reconstruction allowed us to overcome the loss in sensitivity of previously used FBP: this improved the SNR. The studies of symmetry and sparse properties avoided a severe increase of the reconstruction time and of storing space on disk. This fast EM Algorithm is now routinely used for the image reconstruction with the YAP-PET tomograph.

Algorithms↗
PubMedDate not supplied

Prevalence and pattern of epilepsy (Lath/Mirgi/Laran) in rural Kashmir, India.

The rural population of 63,645 living in the mountainous Kuthar Valley of South Kashmir, Northwest India was surveyed to determine the prevalence of major neurologic disorders, including epilepsy (called Lath/Mirgi/Laran in the local language). The survey was done according to a World Health Organization protocol (1981). House-to-house screening was done by Anganwadi workers to identify people with possible epilepsy. The screening questionnaire was translated into local vernacular. Persons who had some indication of a history of seizures or other neurologic disease were subsequently examined by a neurologic team. The diagnostic criteria of Hauser and Kurland (1975) were used to define cases of active epilepsy and seizure classification (ILAE, 1981) was done only with clinical data. One hundred fifty-seven cases of active epilepsy were detected, giving a crude prevalence rate of 2.47/1,000 general population. In those aged less than 14 years, prevalence was 3.18/1,000. Ninety-five (60.5%) of all cases were male; 91% of active epilepsy cases had onset of seizures before age 30 years. Mean age of onset in males was 5.3 years, and in females it was 7.1 years. Mean duration of seizures was 6 years; 78.9% cases had generalized seizures, 74.5% cases were receiving no specific treatment, 99.4% cases were born of home delivery, and 8.9% cases had a positive family history of seizures. Mental retardation was the most common associated abnormality in 22.9% of cases.

Adolescent↗
PubMedDate not supplied

Prevalence and clinical significance of antiphospholipid antibodies to noncardiolipin antigens in systemic lupus erythematosus.

The specificity and immunoglobulin isotype distribution of antiphospholipid (aPL) antibodies have been evaluated in 68 patients with systemic lupus erythematosus (SLE) by ELISA which employed a panel of 7 different PL antigens. A total of 49 patients (72%) were positive for aPL antibodies of different isotypes and directed to one or more PL epitopes. Prevalence of IgG anticardiolipin (aCL, 37%) was similar to that of the other negatively charged PLs phosphatidylserine (PS, 35%), phosphatidylinositol (PI, 35%), phosphatidylglycerol (PG, 35%) and phosphatidic acid (PA, 40%); prevalence reduced to 9-12% and 7-16% respectively for IgM and IgA isotypes to the same antigens. aPL antibodies to the zwitterionic PLs phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were also observed, though their prevalence was lower than that demonstrated for negatively charged PLs. Of the 36 SLE patients who were aCL negative (53%), 17 (25% of all patients and 47% of aCL-negative patients) were positive for aPL antibodies of different isotypes to one or more non-CL epitopes. During a mean follow-up period of 30 months, 10 patients had deep vein thrombosis (DVT) with a total of 21 events. By chi 2 test, a significant correlation was found between DVT and IgG aCL (p = 0.03) and between this event and the presence of lupus anticoagulant (LA) antibody (p = 0.04). However, stronger correlations were demonstrated between DVT and IgA aCL (p = 0.007), IgG anti-PS (p = 0.02), and IgA anti-PC, -PI and -PG (p = 0.02, 0.003 and 0.02, respectively), whereas no correlation was found between thrombotic events and aPL antibodies with PE and PA specificities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Solution structure of deltorphin I at 265 K: a quantitative NMR study.

Deltorphin I, a delta-selective opioid peptide, has been studied in a DMSOd6/H2O cryoprotective mixture by two-dimensional (2D) NMR spectroscopy in the temperature range 260 K to 305 K. The high viscosity of the solvent at low temperature mimics a distinctive physico-chemical feature of cytoplasm and allows the measurement of a NOESY spectrum rich in intra- and inter-residue effects. Backbone NOEs at 265 K can be calculated with good accuracy in terms of only two limiting conformers: one folded, with a mole fraction of 0.30, and another extended with a mole fraction of 0.70. This calculation is still a rough approximation of the complex conformational equilibria existing in solution but, to the best of our knowledge, is the first one for a flexible peptide, and represents an encouraging starting point for a quantitative evaluation of NMR data of small, flexible peptides in solution. The folded conformer consistent with observed NOEs has a shape surprisingly similar to those of unrelated, rigid, delta-selective opiates.

Amino Acid Sequence↗
PubMedDate not supplied

Aortic insufficiency. A multivariate analysis of incremental risk factors for operative mortality and functional results.

The object of this study was to establish which of four chosen preoperative parameters, namely NYHA functional Class, cardio-thoracic ratio (CTR), left ventricular end-diastolic pressure (LVEDP) and ejection fraction (EF), might affect, singly or in combination, the operative risk in isolated, chronic aortic insufficiency (AI). To this purpose we reviewed the records of all adult patients consecutively operated upon in our Department for isolated chronic AI, from 1979 to 1985. Patients with associated cardiac disease, transvalvular aortic gradient, recent endocarditis of a malfunctioning bioprosthesis were excluded from the study, leaving 89 consecutive patients (mean age 47.2 years) for evaluation. St. Jude or Duromedics mechanical prostheses were exclusively used for aortic valve replacement (AVR). Post-operatively all patients received long term anticoagulation. Follow up period ranged from 24 to 109 months (mean 61.8 months). The method of analysis was designed as follows: a) each patient was allocated a positive (+) or a negative (-) variable for the value of each parameter, b) five patient groups were formed on the basis of the free association of parameter variables, c) single variables and their association with early and late mortality, functional results as NYHA Class were compared by statistical methods (chi 2, Student's Test, Wilcoxon Test). The results of the study show: a) only EF significantly influenced early mortality (P less than 0.05), b) late mortality was significantly influenced (P less than 0.001) by NYHA Class and CTR, c) single parameter variables (+ or -) and or their association significantly conditioned functional results.

Aortic Valve↗