324,779 research outputs found
Evaluation of the new Ocuton S tonometer
No full textPurpose: To evaluate the intra- and interobserver variability of the Ocuton S tonometer, its correlation with Goldmann tonometry, the reliability of self-tonometry and the safety of the instrument.
Methods: Thirty-five healthy subjects and 45 patients with primary open-angle glaucoma (POAG), aged from 38 to 80 years (mean age: 64.6 +/- 12.2 years), underwent tonometry with the Ocuton S tonometer in one eye chosen at random. The intra- and interobserver variability between two operators (kappa coefficient), the Ocuton S/Goldmann correlation and the reliability of self-tonometry were evaluated by performing two tonometries on each patient in subgroups. Each tonometry was considered as the mean of three consecutive measurements. Central ultrasonic pachymetry, keratometry and corneal biomicroscopy were also evaluated.
Results: The intra- and interobserver variability ranged from 0.38 to 0.66. The difference between the means of intraocular pressure (IOP) with the Ocuton S (24.4 +/- 4.7 mmHg) and the Goldmann tonometer (18.1 +/- 4.7 mmHg) was statistically significant (p < 0.0001). Linear regression analysis revealed a good Ocuton S/Goldmann correspondence (r = 0.88, p = 0.0001). However, IOP values detected with the Ocuton were consistently overestimated, compared to those detected with the Goldmann tonometer. The correlation between corneal thickness and IOP was statistically significant both for the Goldmann (r = 0.510, p = 0.021) and for the Ocuton S tonometer (r = 0.520, p = 0.019). No correlation was found between keratometry and IOP. The mean measurement obtained by self-tonometry (21.9 +/- 3.6 mmHg) showed no statistically significant difference when compared to the mean measurement obtained by an expert operator (21.3 +/- 3.4 mmHg).
Conclusion: The Ocuton S tonometer is a safe instrument that can be used easily by the patient. However, in comparison to the Goldmann tonometer, it overestimates IOP and requires further technical and methodological refinements in order to ensure greater reliability
Scanning Tunneling Microscopy and Spectroscopy investigations of Graphene on Ru(0001) and (CO+O) on Rh(111)
No full textLinda Talk : suporte distribuido a programação concorrente orientada a objetos
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro TecnologicoProblemas complexos são geralmente decompostos em subproblemas menores, que sejam tratáveis mais facilmente. O mesmo vale para sistemas de computação, os quais contam com uma gama rica de abordagens de decomposição (funcional, procedural, etc). Dentre estas, a decomposição orientada a objetos tem ganho cada vez mais espaço, dada sua riqueza e poder na modelagem e implementação de sistemas informáticos. A possibilidade de programar sistemas multiprocessadores e sistemas em redes de computadores, por outro lado, favoreceu as linhas de programação paralela/concorrente/distribuída. Contudo, se de um lado a orientação a objetos clássica promove uma modelagem natural de entidades no domínio do problema, por outro lado ela falha na tentativa de expressar atividades concorrentes/paralelas. Já sistemas que suportam a noção de processos paralelos, tais como Occam, Conic, Ada, etc, permitem preencher esta lacuna. Contudo, o poder de modelagem e abstração de entidades fica bastante limitado neste tipo de abordagem, levandogeralmente à produção de sistemas difíceis de adaptar, manter e recusar. Modelos com suporte à programação paralela orientada a objetos, tais como Emerald, ConcurrentSmalltalk, Act-1, ABCL/1, etc. surgem na tentativa de unificar objetos no sentido clássico de orientação a objetos com a noção de processos paralelos e comunicantes. Porém, tanto nesta abordagem quanto na programação orientada a objetos clássica e alguns modelos de programação concorrente/paralela/distribuída, a metófora de interação entre objetos/processo é a mesma: troca de mensagens. Troca de mensagens conforme presente em sistemas concorrentes orientados a objetos apresentam diversas fraquezas no que toca a implementação, manutenção e reusabilidade de sistemas distribuídos. Nossa proposta busca incorporar a uma linguagem orientada a objetos clássica - Smalltalk - um modelo que suporte a programação paralela/distribuída com um maior grau de flexibilidade. Este modelo é o de Espaço de Tuplas, de Linda. Através de um pequeno conjunto de primitivas, tem-se um modelo simples de criação e coordenação de processos ortogonal à linguagem em que se insere o modelo (Smalltalk, no caso). Através do uso extensivo do modelo, acreditamos ser possível a construção de sistemas realmente distribuídos e orientados a objetos com um maior grau de flexibilidade em sua implementação, reusabilidade e manutenção
PEPTIDOMIMETICS CONTAINING NEW BIFUNCTIONAL 2,5-DIKETOPIPERAZINE SCAFFOLDS: SYNTHESIS, CONFORMATIONAL ANALYSIS AND USE AS POTENT INTEGRIN LIGANDS
No full textA library of 11 bifunctional 2,5-diketopiperazine (DKP) scaffolds, derived from L- or D-Ser and either L- or D-Asp or D-Glu, was designed and synthesized. All the DKP scaffolds feature a carboxylic acid functionality and an amino group, either protected as Boc or masked as azide, which can be locked in a cis- or trans-relationship as a consequence of the absolute configurations of the two α-amino acids. Moreover, the DKP scaffolds differ from each other for the substitution at the intracyclic nitrogens (N-1, N-4), as they are either mono- or bis-benzylated. The DKP scaffolds, while being derived from α-amino acids, can be seen as constrained dipeptides formed by two β-amino acids or one β- and one γ-amino acid.
Two different synthetic strategies were devised to prepare the mono benzylated scaffolds, depending on the nitrogen substitution (N-1 or N-4). In particular, the synthesis of DKP scaffolds bearing a benzyl group at the serine-derived nitrogen N-4 was accomplished making use of a serine ligation strategy, via the isopeptide.[1] On the other hand, the synthesis of DKP scaffolds bearing a benzyl group at the aspartic acid-derived nitrogen N-1 occurred through the formation of a dipeptide intermediate. Bis N-benzyl substituted scaffolds were easily accessed benzylating mono-substituted advanced intermediates.
An efficient synthesis in solution of eight cyclic peptidomimetics containing a DKP scaffold and the Arg-Gly-Asp (RGD) motif[2] has been developed and optimized. The ligands were tested for their ability to inhibit biotinylated vitronectin binding to integrin αvβ3 and αvβ5 receptors. All the ligands, except for the one containing a cis-scaffold, displayed low nanomolar inhibitory activity for both αVβ3 and αVβ5 integrin receptors, with a slight selectivity in favour of the former receptor. In order to rationalize, on a molecular basis, the affinity of these cyclic RGD peptidomimetics for the αvβ3 receptor, conformational and docking studies were performed by NMR spectroscopy and computational methods.
Two cyclic peptidomimetics containing a DKP scaffold and the isoAsp-Gly-Arg (isoDGR) motif were prepared, combining a solid phase and a solution phase synthetic approach. Very promising results (low nanomolar inhibitory activity) were obtained for their ability to inhibit biotinylated vitronectin binding to the αvβ3 and αvβ5 integrin receptors.
Based on the good results recently obtained by the group of Prof. Oliver Reiser (Univ. Regensburg)[3] in the design of helices, alternating two α- and two β-amino acids, a linear pseudodecapeptide was prepared alternating a cis-DKP, which serves as a ββ-constrained dipeptide, and Ala-Ala as the αα-subunit. The folding properties of the αα,ββ-pseudodecapeptide were studied by NMR spectroscopy, CD spectroscopy and computational methods. The results obtained, though not exhaustive, are indicative of a turn-inducing ability of the cis-DKP.[4]
[1] M. Marchini, M. Mingozzi, R. Colombo, C. Gennari, M. Durini, U. Piarulli, Tetrahedron 2010, 66, 9528-9531.
[2] A. S. M. da Ressurreição, A. Vidu, M. Civera, L. Belvisi, D. Potenza, L. Manzoni, S. Ongeri, C. Gennari, U. Piarulli, Chem. Eur. J. 2009, 15, 12184-12188.
[3] L. Berlicki, L. Pilsl, E. Wéber, I. M. Mándity, C. Cabrele, T. A. Martinek, F. Fülöp, O. Reiser, Angew. Chem. Int. Ed., in press.
[4] a) A. S. M. Ressurreição, A. Bordessa, M. Civera, L. Belvisi, C. Gennari, U. Piarulli, J. Org. Chem. 2008, 73, 652-660; b) R. Delatouche, M. Durini, M. Civera, L. Belvisi, U. Piarulli, Tetrahedron Lett. 2010, 51, 4278-4280
- …
