Biomedical subjects

Marcelo Emílio Beletti

Publications and source records attributed to Marcelo Emílio Beletti.

5 recordsLinked to original sources

PubMed2005

A comparison of morphometric characteristics of sperm from fertile Bos taurus and Bos indicus bulls in Brazil.

The current work has as main objective the systematic investigation of sperm morphometric characteristics of fertile Bos taurus and Bos indicus bulls living in Brazil by using several traditional as well as more modern and advanced computer vision concepts and methodologies. Ten smears of B. taurus semen and ten smears of B. indicus semen have been evaluated. Sperm morphology was quantified in terms of the following morphological features: head area, perimeter, width, length, width:length ratio, ellipticity, shape factor, width of sperm basis, the three first Fourier values, symmetry and hydrodynamics. Morphometric differences have been observed between the sperm cell of B. taurus and B. indicus bulls. The sperm cells of Zebu bulls tend to be smaller and less elliptic, however without modifying hydrodynamic, side symmetry and width of sperm head base. These differences clearly indicate that the geometrical characterization of bull sperm cells should take into account morphological peculiarities that are specific to each subspecies. Another important contribution is the identification that morphological differences implied by bulls of different fertility, as characterized by other authors, were found to be less as compared with those obtained in the current study where highly fertile animals from the two subspecies were studied.

Animals↗

PubMed2005

A spectral framework for sperm shape characterization.

A novel methodology for characterization of animal sperm shape involving the use of a spectral approach to multiscale curvature estimation is proposed. By using the derivative property of the Fourier transform, allied to Gaussian smoothing, accurate estimates of the curvature along the sperm contour can be obtained in such a way that the curvature peaks corresponding to the sperm head vertices can be effectively identified. The measurements derived from such a processing, namely the width of the basal region of the head, the centralization of tail implantation, and the multiscale bending energy, provide valuable resources for fertility and phylogenetic studies.

Animals↗

PubMed2004

Comparison between the toluidine blue stain and the Feulgen reaction for evaluation of rabbit sperm chromatin condensation and their relationship with sperm morphology.

Sperm chromatin alteration is an important feature that can affect fertility of the male rabbit. This study compared toluidine blue staining with Feulgen reaction (as methods for evaluating chromatin alteration) and investigated the relationship between sperm morphology and chromatin alteration. Seven hundred rabbit ejaculates of animals with unknown fertility were used. Primary and secondary morphological sperm abnormalities were evaluated in semen smears with phase-contrast microscopy. Chromatin alterations were evaluated in semen smears stained with toluidine blue (pH 4.0 and 5.0) and with the Feulgen reaction. While the three methods were equally efficacious for identification of chromatin alterations, toluidine blue staining was more appropriate to characterize the intensity of chromatin alterations. The correlation between primary sperm defects and chromatin alteration was high and positive, suggesting that sperm chromatin structure affected sperm head morphology. The correlation between secondary sperm defects and chromatin alteration was also positive, but lower. The final chromatin compaction occurs in the epididymus, where secondary sperm defects originate. Therefore, the causes of secondary sperm defects could also intervene with final chromatin compaction. In summary, the toluidine blue stain was an effective means of evaluating the sperm chromatin alteration in rabbit spermatozoa.

Animals↗

PubMed2004

Use of the n-butyl cyanoacrylate adhesive and the polyglactine thread suture for corneal rhaphy in rabbit (Oryctolagus cunicullus).

The aim of this study was to evaluate the cicatricial repair of perforating cornea in rabbits, by using the N-butyl cyanoacrylate adhesive compared to the 910-polyglactine thread suture through macroscopic and histological assays. Corneas from 18 adult rabbits were perforated and subsequently occluded with N-butyl cyanoacrylate synthetic adhesive (right cornea) or by separated single points using the 910-polyglactine thread (left cornea). The rabbits were divided into groups containing three animals per group. Examination after 7, 15, and 30 days post-operative showed that both the synthetic adhesive and the suture were efficient in the occlusion of the surgical wounds, thus stabilizing the intra-ocular content. The N-butyl cyanoacrylate adhesive was shown to be superior to the 910-polyglactine suture thread with regards to the evolution and the organization of the healing process.

Animals↗

PubMed2003

A systematic approach to multispecies sperm morphometric characterization.

OBJECTIVE: To investigate the morphologic variety of sperm heads between several species through a comprehensive set of measurements, some of which are presented here for the first time, and to perform cluster analysis. STUDY DESIGN: Fifty images were obtained for each species, preprocessed, normalized and characterized through a series of morphologic measures. All possible 2 x 2 combinations of measurements were assessed in terms of objective (discriminant analysis) and subjective (visual inspection) methods. RESULTS: The specific potential of each measure and 2 x 2 combinations were identified with respect to 2 main situations: separation between species and separation of alterations within a species, possibly corresponding to anomalies or subpopulations. Several of the measurements led to reasonable separation between species, and some specific measurements allowed the identification of morphologic alterations. CONCLUSION: The potential of relatively more sophisticated measurements and concepts for sperm analysis was corroborated. Although most of the measures considered were observed to allow good separation between species, some of the measurements, such as hydrodynamic coefficients, anterior-posterior and side symmetry, shape factor and first Fourier descriptor, accounted for the identification of secondary clusters within specific species, possibly indicating pathologic alterations or signaling the presence of subpopulations.

Animals↗