1,720,967 research outputs found
BIOCOMPATIBILITY OF DENTAL MATERIALS: IMMUNOCYTOCHEMICAL EXPRESSION OF EXTRACELLULAR MATRIX MOLECULES AND CELL PROLIFERATION RATES
No full textThe aim of the present work was to investigate the biocompatibility in vitro of biomedical biomaterials employed in stomathology, in order to assess useful biological parameters, i.e. the correlation between cell proliferation rates and the expression of various antigens of the extracellular matrix (ECM), as well as to obtain useful information for the subsequent “in vivo” investigations.. Since in the study of biocompatibility of dental implants many reports have been performed regarding the aspects of osteointegration processes, few studies have examined the relationships between soft tissues and biomaterials. In particular, we would study the relationship between cell proliferation rates of cultured fibroblasts to the immucytochemical expression of molecules involved in cell adhesion mechanisms to ECM, i.e. fibronectin, chondroitin sulfate and a5b1 integrin. We observed that cell proliferation was related in particular to the expression degree of fibronectin. As far as the different dental implant surfaces were concerned, we found that fibronectin exhibited a greater immunocytochemical expression in fibroblasts cultures in the presence of smooth surfaces correlated with higher fibroblast proliferation rates, suggesting that smooth surfaces could allow a better adhesion of cells of the soft oral tissues, i.e. gingival connective tissue. We think these results could be interesting, since the integration of implant dental materials requires not only the best osteointegration, but also an optimal adhesion of gingival soft tissues to the apical part of the same dental implant. These findings could also suggest that dental implant surfaces should be manufactured to obtain the best osteointegration in its deeper part, whereas the best fibroblast adhesion in its apical portion
On the presence of a secondary cartilage in the mental symphyseal region of human embryos and fetuses.
No full textThe presence of a secondary cartilage in the mental symphyseal region was examined in this study. A double-staining method with alcian blue and alizarin red S was performed on both whole human embryos and fetuses (developmental age between 8 and 17 weeks, crown-rump length, CRL, between 37 and 124 mm) and their disjointed mandibles. Histological and histochemical techniques were applied to transverse serial sections of whole disjointed fetal heads. The ossification process observed in the mental symphysis is quite different from that of the mandibular body, whose membranous ossification is induced by the contiguous Meckel's cartilage. No evidence of any fusion of Meckel's cartilage with the symphyseal cartilage, that lies within the symphyseal space, was detected. On the basis of these findings, we suggested that the mental secondary cartilage is able to change into bone according to an endochondral ossification process. Moreover, the role of mechanical causes in the development of the mental symphysis was hypothesized
Developmental pathways of vertebral centra and neural arches in human embryos and fetuses.
No full textThe ossification pathways of both vertebral centra (i.e., vertebral bodies) and neural arches were studied in human embryos and fetuses (CR-length between 38 and 116 mm). A clearing and double-staining method for whole embryo or fetus, using alcian blue and alizarin red S, allowed an easy and precise detection of the morphology of the whole vertebral column and every single vertebra. Both cartilaginous and bony components were clearly visible. Different temporal and topographical patterns of ossification were shown for the centra and arches; the latter were respectively proximal-distal (i.e., bidirectional from a defined starting tract in T10-L1) and cranial-caudal (i.e., monodirectional). The patterns could be related to the morphogenetic processes of other structures (i.e., muscles and nerves). Moreover, the numerical survey of ossification centers provided a possible parameter for the determination of the fetal developmental age. This could be useful in the study of pathological condition
The growth of long bones in human embryological and fetal upper limbs and its relationship to other developmental patterns.
No full textMeasurements were made of the long bones of the upper limbs (humerus, ulna, radius) of 58 aborted embryos and fetuses, developmental age from 8 to 14 weeks, crown-rump length (CRL) between 38 and 116 mm. The specimens were cleared and double-stained, using alcian blue and alizarin red S for a differential detection of cartilage and bone. The values of both the total length (TL) and the ossified part (OL) of each long bone were related to the fetal developmental age previously estimated by freshly measured CRL. The relationship to another developmental pattern, i.e. the number of ossified centres in the vertebral column, suggested that the OL values could be much more significant than TL for the assessment of fetal growth
Immunocytochemical expression of protein kinase C isoenzymes alpha, delta, epsilon and zeta in differentiating chick chondrocytes in vitro.
No full textMandibular growth rates in human fetal development.
No full textA morphometric analysis of changing proportions in the developing mandible was undertaken in 18 human embryos and fetuses of both sexes (developmental age from 8 to 14 weeks, crown-rump length, CRL, from 34 to 110 mm), previously cleared and stained with a specific method for bone (alizarin red S). Reference points were located on the mandible, i.e. condylar process (Pcl), coronoid process (Pco), gnathion (GN), gonion (GO), superior symphyseal point (SSP), for measuring linear dimensions, i.e. Pcl-GN, Pcl-Pco, Pco-GN, GO-GN, SSP-GN. The gonial (Pcl-GO-GN) and the (Pcl-GN-Pcl) angles were also measured. All linear dimensions were correlated with the CRL by bivariate allometry (1n y = 1n a+b 1n x): they all grew with positive allometry, except GO-GN with isometry. The mandibular ramus grew relatively faster than the body, both in length and height, and the greatest growth rate was found for ramus height. The relation between mandibular shape and the craniofacial structures was investigated using scale drawings obtained from photographs of fetal skulls in lateral view. In the youngest fetuses the mandible was prognathic, then became retrognathic. During the period investigated the zygomatic process and squama of the temporal bone were in a lower and more inclined position in relation to the transverse plane passing through the zygomatic arch than in the newborn and adult. This study identifies parameters fitting changing trends in height, length and shape of the human mandible during the prenatal period (8-14 weeks); moreover, it emphasizes that the mandibular growth patterns differ significantly from those of successive development periods
Morphological features and measurements in a human fetus with karyotipe 69,XXX: comparison with fetuses of the same CRL without chromosomal anomalies.
No full textBiocompatibility evaluation of dental metal alloys in vitro: Expression of extracellular matrix molecules and its relationship to cell proliferation rates.
No full textProtein kinase C (PKC) isoenzymes exhibit specific expression in the vertebral column of human fetuses.
No full textRecent studies have shown that protein kinase C (PKC) plays a pivotal role in many cellular functions, i.e. cell proliferation and differentiation, exocytosis, ion-exchange regulation, hormone and neurotransmitter release, programmed cell death. Up to now the tissue and organ distribution of PKC isoenzymes have been studied in various mammalian adults and it has been suggested that each of them could play a specific role in the regulation of various cellular functions. However, few works have been performed on the expression of the enzyme in actively proliferating and differentiating tissues, i.e. during embryonal and fetal developmental stages. In the present study we have performed an immunohistochemical analysis by using polyclonal antibodies in order to verify the distribution of nine PKC isoenzymes in the vertebral column of human fetuses in a key period (8th developmental week), when the most relevant chondrogenetic and osteogenetic processes occur. The detection of the various PKC isoenzymes and their different distribution in the vertebral bodies and in the intervertebral spaces lead to speculate that the appearance, localization and activation of PKC isoforms in chondrocytes might depend on the stage of chondrogenesis and suggest that cartilage and developing bone represent an appropriate cell system to understand the mechanism of signal transduction, which involves the enzyme
Biocompatibility in vitro of titanium dental implants. Immunocytochemical expression of fibronectin and extracellular matrix receptors.
No full textCell-substratum interactions play a peculiar role in cell proliferation, differentiation and migration. They are regulated by various glycoproteins, among which fibronectin, and by receptors connecting cells to the extracellular matrix, i.e. integrins. Therefore, the aim of this study was to correlate the proliferation rates of the human fibroblast line WI-38 cultured in presence of titanium dental implants to cell adhesion capability to substrata. WI-38 fibroblasts were cultured in presence of four dental implants in titanium (one hydroxyapatite coated) for 48, 72 and 96 hours. Cell proliferation was evaluated by detecting 5-bromodeoxyuridine incorporation. Fibronectin organization and alpha5beta1 integrin expression were evidenced by indirect immunofluorescence. A correlation between fibronectin organization and cell proliferation rates was demonstrated: cultures showing fibronectin mainly organized in fibrils presented the highest cell proliferation degrees. After 96 hours, the observed decrease of the number of proliferating cells corresponded to a different fibronectin organization. In presence of the hydroxyapatite coated implant, colocalization of fibronectin and alpha5beta1 integrin was represented in focal contacts in cultures exhibiting the highest proliferation rate, while cells with the lowest proliferation one expressed alpha5beta1 integrin in point contacts. Evidences obtained in this work showed that both the organization of fibronectin and the expression of alpha5beta1 integrin are strictly correlated to cell proliferation rates. Therefore, these parameters could be useful for evaluating the biocompatibility of dental materials in vitro
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