Benedicto Campos Vidal | Universidade Estadual de Campinas (original) (raw)

Papers by Benedicto Campos Vidal

Acta Cirurgica Brasileira, Oct 1, 1999

Clinical Medicine Netprints, Oct 24, 2001

Acta Cirurgica Brasileira, Oct 1, 1999

Molecular Vision, Feb 1, 2007

Purpose: To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis... more Purpose: To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis of proteoglycans (PGs) and collagen fibril organization in human corneal explants. Methods: Human corneas that had been rejected for transplants were obtained at Banco de Olhos of Hospital São Paulo. For each eye pair, one cornea was submitted to refractive surgery, and the other was used as its matched control. After surgery, the corneas were excised from the eyes and immediately placed in a Ham F-12 nutrient mixture containing 35 Ssulfate for the metabolic labeling of PGs. After 24 h incubation, PGs were extracted and identified by a combination of agarose gel electrophoresis and enzymatic degradation with protease and specific glycosaminoglycan lyases. Histopathological and birefringence analysis were performed in fixed tissue slices. Results: A marked decrease in 35 S-sulfate incorporation in PGs was observed in corneal explants that received LASIK, especially concerning dermatan sulfate-PGs, with keratan sulfate-and heparan sulfate-PG synthesis reduced to a lower degree. Only low molecular weight PGs were present in the corneas, both before and 24 h after LASIK. No sign of wound healing processes were observed, but a marked change in corneal birefringence was seen following LASIK treatment. Conclusions: Laser application led to decreased PG biosynthesis in human corneal explants, with marked changes in the collagen fibril organization, as revealed by changes in the tissue birefringence.

Journal of submicroscopic cytology and pathology

The present study focuses on establishing patterns of collagen fibers distribution in prostatic n... more The present study focuses on establishing patterns of collagen fibers distribution in prostatic nodular hyperplasia and adenocarcinomas, in comparison with the normal tissue. Sections of prostatic transurethral resection were subjected to Gömöri's method for collagen fibers and reticulin and analyzed under ordinary and polarized light microscopy. Controls and hyperplastic regions present collagen fibers with variable thickness that run in different directions, establishing a tridimensional network. These fibers exhibit birefringence and dichroism thus demonstrating their fibrillar integrity. On the other hand, increased variability in collagen fiber distribution and anisotropical properties occur in adenocarcinomas evaluated in accordance withthe Gleason's score. In some of their areas, a well-defined collagen network delimitates the base of transformed epithelial cells whereas in other areas the collagen fibers are disorganized and do not establish a boundary between the epithelial structures and the stroma. In these areas, collagen is found in the stroma. It was also observed that adenocarcinoma tumor cells rest on a scaffold of thin and dendritic collagen fibers. Collagen fibers of the prostatic stroma of the adenocarcinomas may show a modification in arrangement and fibrillar compactness. In prostatic nodular hyperplasia, there is no change in collagen molecular integrity, since collagen affinity for silver and collagen birefringence are similar to controls. In adenocarcinoma with high dedifferentiation degree, thin and branched strongly argyrophilic and birefringent collagen fibers are detected in regions of cell proliferation. In the adjacent stroma, hyaline plaques are indicative of matrix degradation or remodellation.

Cell and tissue research, Jan 14, 2015

Entheses are specialized biological structures that functionally anchor tendons to bones. The com... more Entheses are specialized biological structures that functionally anchor tendons to bones. The complexity, mechanical characteristics and properties of the entheses, particularly those related to exercise, mechanical load and pathologies, have been extensively analyzed; however, the macromolecular organization of the enthesis fibers, as assessed by polarization microscopy, has not yet been investigated. Morphological and optical anisotropy characteristics, such as birefringence, linear dichroism (LD) and differential interference contrast (DIC-PLM) properties, are thus analyzed in this study of a healthy adult mouse calcaneal tendon-bone enthesis. The molecular and supramolecular order of collagen and GAGs was determined for the collagen bundles of this enthesis. Based on a birefringence plot pattern as well as on metachromasy and linear dichroism after toluidine blue staining at pH 4.0, a similarity between the calcaneal tendon-bone enthesis and cartilage during ossification may be ...

Analytical Cellular Pathology, 2000

Increased amounts of chromatin condensation (i.e., localized areas of high DNA density, or chroma... more Increased amounts of chromatin condensation (i.e., localized areas of high DNA density, or chromatin higher order packing state) have been described in NIH 3T3 cells transformed with the Ha-ras oncogene. The structural basis for this oncogene-mediated alteration in nuclear organization is unknown. Since DNA methylation is likely to be involved in regulating the nucleosomal level of DNA packaging, we studied the role of DNA methylation in higher-order chromatin organization induced by Ha-ras. CpG-methylated DNA content was estimated in "condensed" chromatin of Ha-ras-transformed NIH 3T3 cell lines which differ in ras expression and ras-induced metastatic ability but present approximately the same values of "condensed" chromatin areas. The question posed was that if DNA methylation were involved with the chromatin higher-order organization induced by Ha-ras in these cell lines, the methylated DNA density in the "condensed" chromatin would also be the same. The DNA evaluation was performed by video image analysis in Feulgen-stained cells previously subjected to treatment with Msp I and Hpa II restriction enzymes, which distinguish between methylated and non-methylated DNA. The amount of methylated CpG sequences not digested by Hpa II in "condensed" chromatin regions was found to vary in the studied ras-transformed cell lines. DNA CpG methylation status is thus suggested not to be involved with the higher order chromatin condensation induced by ras transformation in the mentioned NIH 3T3 cell lines.

Brain and behavior, 2013

The purpose of this study was to investigate the influence of implanting collagen with a supramol... more The purpose of this study was to investigate the influence of implanting collagen with a supramolecular organization on peripheral nerve regeneration, using the sciatic nerve tubulization technique. For this purpose, adult female Sprague Dawley rats were divided into five groups: (1) TP - sciatic nerve repaired with empty polyethylene tubular prothesis (n = 10), (2) TPCL - nerve repair with empty polycaprolactone (PCL) tubing (n = 8), (3) TPCLF - repair with PCL tubing filled with an implant of collagen with a supramolecular organization (n = 10), (4) AG - animals that received a peripheral nerve autograft (n = 8), and (5) Normal nerves (n = 8). The results were assessed by quantification of the regenerated fibers, nerve morphometry, and transmission electron microscopy, 60 days after surgery. Immunohistochemistry and polarization microscopy were also used to analyze the regenerated nerve structure and cellular elements. The results showed that the AG group presented a larger number...

International Urogynecology Journal, 2014

Collagen has been proposed to be a useful biomaterial, but previous attempts to combine meshes wi... more Collagen has been proposed to be a useful biomaterial, but previous attempts to combine meshes with a collagen membrane have failed. The objective was to verify the effect of high-purified collagen gel coating in the immune-inflammatory response, host collagen metabolism, and angiogenesis around polypropylene mesh. In 20 female Wistar rats were implanted, at one side of the abdominal wall, a monofilament polypropylene mesh (PP), and, on the other side, a mesh coated with a new highly purified collagen gel (PPC). The animals were divided into sub-groups and euthanized at 7, 14, 21, and 90 days after implantation. Immunohistochemical analysis was performed using interleukin 1 (IL-1), matrix metalloproteinases (MMP-2, MMP-3), surface antigen CD-31, and tumor necrosis factor (TNF-α). Objective analysis (percent reactive area, average density, and vessels concentration) was performed using AxioVision Software. Comparative analysis showed: higher vessel density in the PPC group after 14 days (p = 0.002); a decrease in the average density of MMP-2 in the PPC group after 21 and 90 days (p = 0.046); more stability in the behavior of MMP-3 in the PPC group throughout the periods with the percentage reactive area for MMP-3 showing a significant decrease just in the PP group after 14 and 90 days (p = 0.017), and also for MMP-3 average density, in which reduction was significant after 21 days in the PP group, but not until after 90 days in PPC group (p < 0.001). Highly purified collagen coating causes significant changes in angiogenesis and in the immune reaction of metalloproteinase around mesh implants in rats. These findings can be useful for improving mesh biocompatibility for pelvic floor surgery if such effects could be properly controlled.

Ultrasound in Medicine and Biology, 2001

The purpose of this study was to evaluate the effects of therapeutic ultrasound (US) on the heali... more The purpose of this study was to evaluate the effects of therapeutic ultrasound (US) on the healing process in the Achilles tendon (Tendo calcaneus) of Wistar rats after tenotomy. Sonication was performed at a frequency of 1 MHz, an intensity of 0.5 W/cm(2) (SATA), for 5 min, over a period of 14 consecutive days in two modalities (n = 15); in both continuous and pulsed modes. The control group was divided into tenotomized, mock-sonicated and nontenotomized tendons (n = 15). On the 15th postoperative day, the tendons were removed and analyzed by using the polarized light microscopy, with the purpose of detecting and measuring the organization of collagen fibers through birefringence. The results showed a high birefringence for the tendons treated using the pulsed mode (p < 0.001), revealing the best organization and aggregation of collagen bundles. Sonication in the continuous mode induced a decrease (p = 0.047) in the ability to quicken the healing process. These findings suggest that US therapy is beneficial in the early healing process of tendons when the pulsed mode is used.

Molecular vision, 2007

To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis of prote... more To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis of proteoglycans (PGs) and collagen fibril organization in human corneal explants. Human corneas that had been rejected for transplants were obtained at Banco de Olhos of Hospital São Paulo. For each eye pair, one cornea was submitted to refractive surgery, and the other was used as its matched control. After surgery, the corneas were excised from the eyes and immediately placed in a Ham F-12 nutrient mixture containing (35)S-sulfate for the metabolic labeling of PGs. After 24 h incubation, PGs were extracted and identified by a combination of agarose gel electrophoresis and enzymatic degradation with protease and specific glycosaminoglycan lyases. Histopathological and birefringence analysis were performed in fixed tissue slices. A marked decrease in (35)S-sulfate incorporation in PGs was observed in corneal explants that received LASIK, especially concerning dermatan sulfate-PGs, with keratan ...

European Urology Supplements, 2012

PLoS ONE, 2013

Background: Birefringence can reveal much of the morphology, molecular order, heterogeneity of fi... more Background: Birefringence can reveal much of the morphology, molecular order, heterogeneity of fiber orientation, and nonlinear optical properties of biopolymers such as collagen. However, the detailed characterization of skin collagen fibers using optical anisotropy methods remains elusive. A clear understanding of collagen fiber organization in skin tissues may be important in the interpretation of their structural-functional relationships under normal and pathological conditions. In this study, fiber orientation in collagen bundles (CBs) and their supramolecular organization were examined in rat skin using polarization microscopy and image analysis.

Toxicological & Environmental Chemistry, 2004

The aim of this work was to examine the induction of cell death by aluminium (Al) at low pH, wher... more The aim of this work was to examine the induction of cell death by aluminium (Al) at low pH, where the toxic cation Al has maximum activity. Chinese hamster V79 fibroblasts were used as a model to study the toxic effects of different Al concentrations under optimal conditions for Al activity (pH 4.5). Al was detected by 8-hydroxyquinoline staining and

Photomedicine and Laser Surgery, 2006

The objective of this study was to evaluate the effects of 685-and 830-nm laser irradiations, at ... more The objective of this study was to evaluate the effects of 685-and 830-nm laser irradiations, at different fluences on the healing process of Achilles tendon of mice after tenotomy.

Micron, 2011

Heterochromatin bodies in single-and multichromocentered interphase cell nuclei of Triatoma infes... more Heterochromatin bodies in single-and multichromocentered interphase cell nuclei of Triatoma infestans, a vector of Chagas disease, have been suggested to contain AT-rich DNA, based on their positive response to Q-banding and Hoechst 33248 treatment. No information exists on whether GC-rich DNA is also present in these nuclei and whether it plays a role on chromatin condensation. Considering that methodologies more precise than those previously used to determine DNA base composition in situ are currently available, and that the spatial distribution of chromatin areas differing in composition in interphase cell nuclei of different species is a matter of interest, the localization of AT-and GC-rich DNA in T. infestans nuclei is revisited here. The methodologies used included DAPI/AMD and CMA 3 /Distamycin differential staining, Feulgen-DNA image analysis following Msp I and Hpa II enzymatic digestion, 5-methylcytidine immunodetection, AgNOR response, confocal microscopy, and the 5-aza-2 -deoxycytidine (5-AZA) demethylation assay. The results identified the presence of AT-rich/GC-poor DNA in chromocenters and evenly distributed AT and GC sequences in euchromatin. A GC-rich DNA zone encircling the chromocenters was also found but it could not be associated with NOR regions. To corroborate the DNA AT-richness in T. infestans nuclei, bioinformatic analyses were also performed. Methylated cytosine was evident at some points of the chromocenters' edge in single-and multichromocentered nuclei and at the euchromatin of multichromocentered nuclei and could be transiently affected by the 5-AZA treatment. The present results suggest that in the particular case of chromocenters of the hemipteran T. infestans, cytosine methylation is not a relevant factor involved in chromatin condensation.

Micron, 2002

The high positive linear dichroism (LD) exhibited by silver-impregnated collagen fibers are thoug... more The high positive linear dichroism (LD) exhibited by silver-impregnated collagen fibers are thought to be caused by an ordered binding of silver nanoparticles to the collagen fibers. A correlation between LD, established by image analysis, and the size of silver particles as measured by electron microscopy was investigated in the same sections of silver-impregnated tendon collagen fibers. Silver particles were found to be periodically ordered along the collagen fibers, with some preference for the 67 nm collagen period and collagen a bands. The silver particle diameter for a sample of n=279 was 18.51 nm on average, with 95% of the values ranging between 17.90 and 19.14 nm. The finding that interference colors are correlated to abnormal dispersion of birefringence characteristics supports the concept that collagen fibers induce an ordered binding of silver distributed along the fibers.

Micron, 2006

Tendons are parallel arrays of collagenous fibers which are specialized in resisting and transmit... more Tendons are parallel arrays of collagenous fibers which are specialized in resisting and transmitting tensile forces. In this work we examined the structure of the superficial digital flexor tendon (SDFT) and the deep digital flexor tendon (DDFT) of pigs, which are considered ''wrap around'' tendons and so receive compression and tension forces. In both tendons, fibrocartilaginous areas were observed in the regions subjected to compression plus frictional loading. Histological and ultrastructural analyses of the tensional region showed an extracellular matrix (ECM) rich in collagen bundles, that were all arranged in the same direction. Fibroblasts were seen closely associated with the collagen bundles. Chondrocytelike cells and high levels of glycosaminoglycans (GAGs) were observed in the compressional regions. The collagen bundles in the compressional region were arranged in several directions and were associated with proteoglycans (PGs). The crimp pattern detected in the tensional region showed that the collagen fibrils were ordered aggregates which formed helical superstructures. #

Acta Cirurgica Brasileira, Oct 1, 1999

Clinical Medicine Netprints, Oct 24, 2001

Acta Cirurgica Brasileira, Oct 1, 1999

Molecular Vision, Feb 1, 2007

Purpose: To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis... more Purpose: To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis of proteoglycans (PGs) and collagen fibril organization in human corneal explants. Methods: Human corneas that had been rejected for transplants were obtained at Banco de Olhos of Hospital São Paulo. For each eye pair, one cornea was submitted to refractive surgery, and the other was used as its matched control. After surgery, the corneas were excised from the eyes and immediately placed in a Ham F-12 nutrient mixture containing 35 Ssulfate for the metabolic labeling of PGs. After 24 h incubation, PGs were extracted and identified by a combination of agarose gel electrophoresis and enzymatic degradation with protease and specific glycosaminoglycan lyases. Histopathological and birefringence analysis were performed in fixed tissue slices. Results: A marked decrease in 35 S-sulfate incorporation in PGs was observed in corneal explants that received LASIK, especially concerning dermatan sulfate-PGs, with keratan sulfate-and heparan sulfate-PG synthesis reduced to a lower degree. Only low molecular weight PGs were present in the corneas, both before and 24 h after LASIK. No sign of wound healing processes were observed, but a marked change in corneal birefringence was seen following LASIK treatment. Conclusions: Laser application led to decreased PG biosynthesis in human corneal explants, with marked changes in the collagen fibril organization, as revealed by changes in the tissue birefringence.

Journal of submicroscopic cytology and pathology

The present study focuses on establishing patterns of collagen fibers distribution in prostatic n... more The present study focuses on establishing patterns of collagen fibers distribution in prostatic nodular hyperplasia and adenocarcinomas, in comparison with the normal tissue. Sections of prostatic transurethral resection were subjected to Gömöri's method for collagen fibers and reticulin and analyzed under ordinary and polarized light microscopy. Controls and hyperplastic regions present collagen fibers with variable thickness that run in different directions, establishing a tridimensional network. These fibers exhibit birefringence and dichroism thus demonstrating their fibrillar integrity. On the other hand, increased variability in collagen fiber distribution and anisotropical properties occur in adenocarcinomas evaluated in accordance withthe Gleason's score. In some of their areas, a well-defined collagen network delimitates the base of transformed epithelial cells whereas in other areas the collagen fibers are disorganized and do not establish a boundary between the epithelial structures and the stroma. In these areas, collagen is found in the stroma. It was also observed that adenocarcinoma tumor cells rest on a scaffold of thin and dendritic collagen fibers. Collagen fibers of the prostatic stroma of the adenocarcinomas may show a modification in arrangement and fibrillar compactness. In prostatic nodular hyperplasia, there is no change in collagen molecular integrity, since collagen affinity for silver and collagen birefringence are similar to controls. In adenocarcinoma with high dedifferentiation degree, thin and branched strongly argyrophilic and birefringent collagen fibers are detected in regions of cell proliferation. In the adjacent stroma, hyaline plaques are indicative of matrix degradation or remodellation.

Cell and tissue research, Jan 14, 2015

Entheses are specialized biological structures that functionally anchor tendons to bones. The com... more Entheses are specialized biological structures that functionally anchor tendons to bones. The complexity, mechanical characteristics and properties of the entheses, particularly those related to exercise, mechanical load and pathologies, have been extensively analyzed; however, the macromolecular organization of the enthesis fibers, as assessed by polarization microscopy, has not yet been investigated. Morphological and optical anisotropy characteristics, such as birefringence, linear dichroism (LD) and differential interference contrast (DIC-PLM) properties, are thus analyzed in this study of a healthy adult mouse calcaneal tendon-bone enthesis. The molecular and supramolecular order of collagen and GAGs was determined for the collagen bundles of this enthesis. Based on a birefringence plot pattern as well as on metachromasy and linear dichroism after toluidine blue staining at pH 4.0, a similarity between the calcaneal tendon-bone enthesis and cartilage during ossification may be ...

Analytical Cellular Pathology, 2000

Increased amounts of chromatin condensation (i.e., localized areas of high DNA density, or chroma... more Increased amounts of chromatin condensation (i.e., localized areas of high DNA density, or chromatin higher order packing state) have been described in NIH 3T3 cells transformed with the Ha-ras oncogene. The structural basis for this oncogene-mediated alteration in nuclear organization is unknown. Since DNA methylation is likely to be involved in regulating the nucleosomal level of DNA packaging, we studied the role of DNA methylation in higher-order chromatin organization induced by Ha-ras. CpG-methylated DNA content was estimated in "condensed" chromatin of Ha-ras-transformed NIH 3T3 cell lines which differ in ras expression and ras-induced metastatic ability but present approximately the same values of "condensed" chromatin areas. The question posed was that if DNA methylation were involved with the chromatin higher-order organization induced by Ha-ras in these cell lines, the methylated DNA density in the "condensed" chromatin would also be the same. The DNA evaluation was performed by video image analysis in Feulgen-stained cells previously subjected to treatment with Msp I and Hpa II restriction enzymes, which distinguish between methylated and non-methylated DNA. The amount of methylated CpG sequences not digested by Hpa II in "condensed" chromatin regions was found to vary in the studied ras-transformed cell lines. DNA CpG methylation status is thus suggested not to be involved with the higher order chromatin condensation induced by ras transformation in the mentioned NIH 3T3 cell lines.

Brain and behavior, 2013

The purpose of this study was to investigate the influence of implanting collagen with a supramol... more The purpose of this study was to investigate the influence of implanting collagen with a supramolecular organization on peripheral nerve regeneration, using the sciatic nerve tubulization technique. For this purpose, adult female Sprague Dawley rats were divided into five groups: (1) TP - sciatic nerve repaired with empty polyethylene tubular prothesis (n = 10), (2) TPCL - nerve repair with empty polycaprolactone (PCL) tubing (n = 8), (3) TPCLF - repair with PCL tubing filled with an implant of collagen with a supramolecular organization (n = 10), (4) AG - animals that received a peripheral nerve autograft (n = 8), and (5) Normal nerves (n = 8). The results were assessed by quantification of the regenerated fibers, nerve morphometry, and transmission electron microscopy, 60 days after surgery. Immunohistochemistry and polarization microscopy were also used to analyze the regenerated nerve structure and cellular elements. The results showed that the AG group presented a larger number...

International Urogynecology Journal, 2014

Collagen has been proposed to be a useful biomaterial, but previous attempts to combine meshes wi... more Collagen has been proposed to be a useful biomaterial, but previous attempts to combine meshes with a collagen membrane have failed. The objective was to verify the effect of high-purified collagen gel coating in the immune-inflammatory response, host collagen metabolism, and angiogenesis around polypropylene mesh. In 20 female Wistar rats were implanted, at one side of the abdominal wall, a monofilament polypropylene mesh (PP), and, on the other side, a mesh coated with a new highly purified collagen gel (PPC). The animals were divided into sub-groups and euthanized at 7, 14, 21, and 90 days after implantation. Immunohistochemical analysis was performed using interleukin 1 (IL-1), matrix metalloproteinases (MMP-2, MMP-3), surface antigen CD-31, and tumor necrosis factor (TNF-α). Objective analysis (percent reactive area, average density, and vessels concentration) was performed using AxioVision Software. Comparative analysis showed: higher vessel density in the PPC group after 14 days (p = 0.002); a decrease in the average density of MMP-2 in the PPC group after 21 and 90 days (p = 0.046); more stability in the behavior of MMP-3 in the PPC group throughout the periods with the percentage reactive area for MMP-3 showing a significant decrease just in the PP group after 14 and 90 days (p = 0.017), and also for MMP-3 average density, in which reduction was significant after 21 days in the PP group, but not until after 90 days in PPC group (p < 0.001). Highly purified collagen coating causes significant changes in angiogenesis and in the immune reaction of metalloproteinase around mesh implants in rats. These findings can be useful for improving mesh biocompatibility for pelvic floor surgery if such effects could be properly controlled.

Ultrasound in Medicine and Biology, 2001

The purpose of this study was to evaluate the effects of therapeutic ultrasound (US) on the heali... more The purpose of this study was to evaluate the effects of therapeutic ultrasound (US) on the healing process in the Achilles tendon (Tendo calcaneus) of Wistar rats after tenotomy. Sonication was performed at a frequency of 1 MHz, an intensity of 0.5 W/cm(2) (SATA), for 5 min, over a period of 14 consecutive days in two modalities (n = 15); in both continuous and pulsed modes. The control group was divided into tenotomized, mock-sonicated and nontenotomized tendons (n = 15). On the 15th postoperative day, the tendons were removed and analyzed by using the polarized light microscopy, with the purpose of detecting and measuring the organization of collagen fibers through birefringence. The results showed a high birefringence for the tendons treated using the pulsed mode (p < 0.001), revealing the best organization and aggregation of collagen bundles. Sonication in the continuous mode induced a decrease (p = 0.047) in the ability to quicken the healing process. These findings suggest that US therapy is beneficial in the early healing process of tendons when the pulsed mode is used.

Molecular vision, 2007

To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis of prote... more To evaluate the acute effects of laser in situ keratomileusis (LASIK) upon the synthesis of proteoglycans (PGs) and collagen fibril organization in human corneal explants. Human corneas that had been rejected for transplants were obtained at Banco de Olhos of Hospital São Paulo. For each eye pair, one cornea was submitted to refractive surgery, and the other was used as its matched control. After surgery, the corneas were excised from the eyes and immediately placed in a Ham F-12 nutrient mixture containing (35)S-sulfate for the metabolic labeling of PGs. After 24 h incubation, PGs were extracted and identified by a combination of agarose gel electrophoresis and enzymatic degradation with protease and specific glycosaminoglycan lyases. Histopathological and birefringence analysis were performed in fixed tissue slices. A marked decrease in (35)S-sulfate incorporation in PGs was observed in corneal explants that received LASIK, especially concerning dermatan sulfate-PGs, with keratan ...

European Urology Supplements, 2012

PLoS ONE, 2013

Background: Birefringence can reveal much of the morphology, molecular order, heterogeneity of fi... more Background: Birefringence can reveal much of the morphology, molecular order, heterogeneity of fiber orientation, and nonlinear optical properties of biopolymers such as collagen. However, the detailed characterization of skin collagen fibers using optical anisotropy methods remains elusive. A clear understanding of collagen fiber organization in skin tissues may be important in the interpretation of their structural-functional relationships under normal and pathological conditions. In this study, fiber orientation in collagen bundles (CBs) and their supramolecular organization were examined in rat skin using polarization microscopy and image analysis.

Toxicological & Environmental Chemistry, 2004

The aim of this work was to examine the induction of cell death by aluminium (Al) at low pH, wher... more The aim of this work was to examine the induction of cell death by aluminium (Al) at low pH, where the toxic cation Al has maximum activity. Chinese hamster V79 fibroblasts were used as a model to study the toxic effects of different Al concentrations under optimal conditions for Al activity (pH 4.5). Al was detected by 8-hydroxyquinoline staining and

Photomedicine and Laser Surgery, 2006

The objective of this study was to evaluate the effects of 685-and 830-nm laser irradiations, at ... more The objective of this study was to evaluate the effects of 685-and 830-nm laser irradiations, at different fluences on the healing process of Achilles tendon of mice after tenotomy.

Micron, 2011

Heterochromatin bodies in single-and multichromocentered interphase cell nuclei of Triatoma infes... more Heterochromatin bodies in single-and multichromocentered interphase cell nuclei of Triatoma infestans, a vector of Chagas disease, have been suggested to contain AT-rich DNA, based on their positive response to Q-banding and Hoechst 33248 treatment. No information exists on whether GC-rich DNA is also present in these nuclei and whether it plays a role on chromatin condensation. Considering that methodologies more precise than those previously used to determine DNA base composition in situ are currently available, and that the spatial distribution of chromatin areas differing in composition in interphase cell nuclei of different species is a matter of interest, the localization of AT-and GC-rich DNA in T. infestans nuclei is revisited here. The methodologies used included DAPI/AMD and CMA 3 /Distamycin differential staining, Feulgen-DNA image analysis following Msp I and Hpa II enzymatic digestion, 5-methylcytidine immunodetection, AgNOR response, confocal microscopy, and the 5-aza-2 -deoxycytidine (5-AZA) demethylation assay. The results identified the presence of AT-rich/GC-poor DNA in chromocenters and evenly distributed AT and GC sequences in euchromatin. A GC-rich DNA zone encircling the chromocenters was also found but it could not be associated with NOR regions. To corroborate the DNA AT-richness in T. infestans nuclei, bioinformatic analyses were also performed. Methylated cytosine was evident at some points of the chromocenters' edge in single-and multichromocentered nuclei and at the euchromatin of multichromocentered nuclei and could be transiently affected by the 5-AZA treatment. The present results suggest that in the particular case of chromocenters of the hemipteran T. infestans, cytosine methylation is not a relevant factor involved in chromatin condensation.

Micron, 2002

The high positive linear dichroism (LD) exhibited by silver-impregnated collagen fibers are thoug... more The high positive linear dichroism (LD) exhibited by silver-impregnated collagen fibers are thought to be caused by an ordered binding of silver nanoparticles to the collagen fibers. A correlation between LD, established by image analysis, and the size of silver particles as measured by electron microscopy was investigated in the same sections of silver-impregnated tendon collagen fibers. Silver particles were found to be periodically ordered along the collagen fibers, with some preference for the 67 nm collagen period and collagen a bands. The silver particle diameter for a sample of n=279 was 18.51 nm on average, with 95% of the values ranging between 17.90 and 19.14 nm. The finding that interference colors are correlated to abnormal dispersion of birefringence characteristics supports the concept that collagen fibers induce an ordered binding of silver distributed along the fibers.

Micron, 2006

Tendons are parallel arrays of collagenous fibers which are specialized in resisting and transmit... more Tendons are parallel arrays of collagenous fibers which are specialized in resisting and transmitting tensile forces. In this work we examined the structure of the superficial digital flexor tendon (SDFT) and the deep digital flexor tendon (DDFT) of pigs, which are considered ''wrap around'' tendons and so receive compression and tension forces. In both tendons, fibrocartilaginous areas were observed in the regions subjected to compression plus frictional loading. Histological and ultrastructural analyses of the tensional region showed an extracellular matrix (ECM) rich in collagen bundles, that were all arranged in the same direction. Fibroblasts were seen closely associated with the collagen bundles. Chondrocytelike cells and high levels of glycosaminoglycans (GAGs) were observed in the compressional regions. The collagen bundles in the compressional region were arranged in several directions and were associated with proteoglycans (PGs). The crimp pattern detected in the tensional region showed that the collagen fibrils were ordered aggregates which formed helical superstructures. #