Comparison of the solophenyl-red polarization method and the immunohistochemical analysis for collagen type III

In the present study, we have compared the staining pattern of the Solophenyl-Red 3 BL-method for the visualization of collagen type III with the immunohistochemical staining in serial sections from 7 skin wounds (wound age 3 days up to 4 weeks) to elucidate the specifity of the histochemical staining method. Large amounts of collagen type III were clearly detectable in the investigated wounds using the immunohistochemical technique. In the sections stained with Solophenyl-Red, however, only 3 out of 7 skin lesions showed a significant positive red staining at the wound margin or in the granulation tissue, while the adjacent normal connective tissue revealed a typical intensive staining. Using polarization microscopy no characteristic bright green fibrils, as reported for collagen type 111, could be seen in the wound areas without positive Solophenyl-Red staining. Since the localization of collagen type III detected by immunohistochemistry and the presumed distribution of this collagen type by the Solophenyl-Red method was not identical, the histochemical polarization method has to be regarded as non-specific for visualization of this collagen type

Incremental markings of enamel in ectothermal vertebrates

The deposition of enamel is marked by the formation of growth lines, which reflect incremental growth. Although periodic markings have been observed in enamel of non-mammalian vertebrates, the cross-striation interval and the pattern of enamel deposition have not been formally investigated. Here a structural study was made of the enamel in four non-mammalian vertebrates, with emphasis on periodic markings. Teeth from Rana catesbeiana, Tropidurus torquatus, Caiman crocodilus and a Canadian carnosaur were analysed. Enamel of T. torquatus and R. castebeiana was aprismatic; that of C. crocodilus and the carnosaur was formed by large, prism-like structures. Conspicuous incremental lines were observed in the enamel of the three living species, which presented a cross-striation repeat smaller than the prism cross-striations of mammalian enamel. Incremental lines of carnosaur enamel had a mean repeat interval similar to that of mammalian prism cross-striations. As metabolic activity in ectotherms is influenced by environmental conditions, the analysis of incremental markings of enamel is a potentially valuable source of information in the study of living and fossil reptiles and amphibians. (C) 2000 Elsevier Science Ltd. All rights reserved.45536336

Variation of tooth number in mammalian dentition: connecting genetics, development, and evolution

A major question in modern biology is how gene mutations affect development and are translated into macroevolutionary changes in morphology. Variations in tooth number, a strategy used by many mammals to develop specialized dentitions, has been an important factor for species diversification. Changes in the number of teeth tend to occur in the reverse of the order teeth are formed during development, which also characterizes the general pattern of tooth loss observed during the evolution of placental mammals. To understand how changes at the molecular level affect the distinct stages of tooth development, we analyzed the ontogenesis of tooth growth arrest in sciurids and mice and in single and double knockout mutant mice. We show that the complexity of the genetic network that governs tooth development can change during ontogenetic trajectory, and these changes may be related to macroevolutionary changes. Furthermore, we show that the variation in tooth number in the affected members of human families bearing mutations in the MSX1 and PAX9 genes can help to understand how the genetic variations within a population can modulate evolutionary changes in dental patterning.5329530

Molecular strategies in the evolution of mammalian dental patterning

The acquisition of masticatory capability by mammals allowed a better processing of food and a consequent increase in the efficiency of nutrients intake by the digestive system. The development of tooth classes and variations in tooth number can be considered intrinsic characteristics of mammalian dentition. These features allowed species to develop specialized dentitions, creating new adaptive zones. Comparative developmental data from knockout mutant mice and human tooth agenesis present new insights on the molecular strategies that permitted rapid phenotypic differentiation, adaptation and speciation of mammalian dentition.151737

Basement membrane associated changes in the rat ventral prostate following castration

This study focuses on the basement membrane associated modifications that take place after androgen blockade, by studying some of its main components, through histochemical, immunohistochemical and Western blotting tests, and its ultrastructural aspects. It was demonstrated that laminin and collagen type IV remain associated with a thickened basement membrane and that there is an apparent increase in heparan sulfate content 21 days after castration. Ultrastructurally, basal lamina appeared extensively folded and pleated. It was also observed that detachment of epithelial cells is not dependent of basal lamina degradation and that the free basal lamina surfaces are folded by the action of adjacent cells. We have also observed some aspects of smooth muscle cell degeneration and death, that lead to modifications of the associated basal lamina. In this case, residual basal lamina also shows extensive folding. The results suggested that degradation of excess basement membrane does not occur or is a very slow process within the period examined, and that basement membrane is left re-organized but ultrastructurally and compositionally unaffected. (C) 1996 Academic Press Limited.201280981

Automated biometrics-based personal identification of the Hunter-Schreger bands of dental enamel

The use of automated biometrics-based personal identification systems is a ubiquitous procedure in present times. Biometrics has certain limitations, such as in cases when bodies are decomposed, burned, or only small fragments of calcified tissues remain. Dental enamel is the most mineralized tissue of organisms and resists post-mortem degradation. It is characterized by layers of prisms of regularly alternating directions, known as Hunter-Schreger bands (HSB). In this article, we show that the pattern variation of the HSB, referred here as toothprint, can be used as a biometric-based parameter for personal identification in automated systems.27315901155115

DIVERSITY OF COLLAGEN EXPRESSION IN THE PLEOMORPHIC ADENOMA OF THE PAROTID-GLAND

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A study in situ of the effect of metallo- and serine proteinase inhibitors on the birefringence of the secretory stage enamel organic extracellular matrix

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Dental enamel formation occurs extracellularly and establishment of an ordered enamel organic extracellular matrix (ECM) seems to be crucial for proper construction of the enamel mineral phase. Polarizing microscopy shows that the ordered supramolecular structure of the secretory stage enamel organic ECM exhibits strong birefringence. We reported earlier that this birefringence is lost in unfixed specimens, probably due to extensive proteolytic cleavage of enamel proteins. Therefore, we investigated the association between enamel proteinase activities by analyzing the effects of metallo-and serine proteinase inhibitors in situ on the birefringence of the secretory stage enamel organic ECM. Male rats were used in the present study. After sacrifice, distal 10 mm fragments of upper incisors were removed and immersed for 15 h under continuous shaking at 37 degrees C in one of the following solutions: 1) 10 mM Tris, pH 8.0; 150 mM NaCl (negative control, n = 8); 2) 2% paraformaldehyde and 0.5% glutaraldehyde in 0.2 M phosphate-buffered saline (PBS), pH 7.2 (positive control, n = 5); 3) 10 mM Tris, pH 8.0; 150 mM NaCl; 2 mM 1,10-phenanthroline (n = 9); 4) 10 mM Tris, pH 8.0; 150 mM NaCl; 2 mM phenylmethyl-sulfonyl fluoride (PMSF) (n = 8); 5) 10 mM Tris, pH 8.0; 150 mM NaCl; 2 mM 1,10-phenanthroline; 2 mM PMSF (n = 9). Samples then were immersed in fixative solution for 24 h and processed to obtain 5 mu m thick longitudinal sections of the secretory stage enamel organic ECM. The sections were immersed in 80% glycerin for 30 min and analyzed by transmitted polarizing light microscopy. 1,10-Phenanthroline (inhibitor of metalloproteinases) and 1,10-phenanthroline + PMSF (inhibitor of serine proteinases) clearly prevented a decrease in the optical retardation of birefringence brightness from the tissue. PMSF alone promoted a slight preservation of the birefringence exhibited by the secretory stage enamel organic ECM. Rapid loss of birefringence in secretory stage enamel organic ECM that is not fixed immediately is caused by enamel proteinases and the activity of metalloproteinases seems to lead to preliminary degradation of the enamel organic ECM, which in turn facilitates subsequent serine proteinase activity.862108114Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [04/13255-8, 04/10994-4

Inhibition of human gelatinases by metals released from dental amalgam

The interaction between metal ions and the oral environment is a major subject matter in dental research. Matrix metalloproteinases (MMPs) have been implicated in pathologic oral processes such as periodontal tissue destruction, root caries, tumor invasion and temporomandibular joint disorders. The aim of this study was to test the effect of metal ions released From dental amalgam on the major gingival gelatinolytic MMPs. Gingival human explants were cultured overnight in DMEM and the activity of secreted enzymes was analyzed by gelatin zymography in buffers conditioned with dispersed phase or concentional phase dental amalgams. The major enzymes present in conditioned media were characterized as MMP-2 and MMP-9 by immunoprecipitation. The proteolytic activities of MMP-2 and MMP-9 were strongly inhibited by dispersed phase amalgams conditioned buffers. Inhibition of MMP-2 and MMP-9 activities was partly prevented by the addition of 1.10 phenanthroline, a divalent metal chelator, to the amalgam conditioned buffers. Dental amalgam conditioned buffer also inhibited the degradation of denatured type I collagen by purified MMP-2 on liquid phase assays. These findings suggest that the activity of oral tissue MMPs may be modulated by metal ions released from dental amalgam. (C) 2001 Elsevier Science Ltd. All rights reserved.22142025203

Extraction of genomic DNA from paraffin-embedded of human fetuses fixed and stored in formalin for long tissue sections periods

The advent of polymerase chain reaction (PCR) technology has increased the interest in fetal specimens housed in anatomy museums, as they may represent a unique source of genetic material for the study of uncommon or rare pathological conditions such as congenital malformations, neoplastic processes and parasitic as well as other infectious diseases. The aim of this study is to evaluate the quality of genomic DNA extracted from paraffin-embedded tissue sections of human fetuses that have been maintained in formalin for several years. Fetal tissues were embedded in paraffin, and tissue sections were submitted to ethanol/xylene dewaxing, followed by DNA extraction with ammonium acetate. DNA fragments were amplified from DNA extracted from formalin-fixed tissue sections, but not from Bouin-fixed tissues (average yield of 13.7 mu g/ml from 10 umbilical cord sections of 10 mu m; A(260):A(280) = 1.55,). The addition of bovine serum albumim increased the yield of PCR amplification. Genomic DNA can be reliably amplified from paraffin-embedded human fetal tissues that had been fixed in formalin during 19 years and used for microdissection studies. This simple, cost-effective, and non-laborious method should facilitate the molecular analysis of a large number of specimens fixed for long periods of time. (C) 2008 Elsevier GmbH. All rights reserved.204963363