Expression of estrogen-related receptor gamma (ERRgamma) in human skin.

Skin is a non-classical target for estrogens. Despite evidence showing that estrogen receptors (ER) are expressed in skin, there are still extensive gaps in our understanding of how estrogens exert their action in non-reproductive tissues. Estrogen-related receptor gamma (ERRgamma), an orphan member of the nuclear receptor superfamily, shows a strong sequence homology with estrogen receptor alpha but it does not bind estradiol.

Activation of fibroblast metabolism in a dermal and skin equivalent model: a screening test for activity of peptides.

Skin firmness, elasticity and tone are gradually lost with age. These changes originate in the dermis and correspond to a decrease in the ability of cells, particularly the fibroblasts, to regenerate the molecules which make up the extracellular matrix. Skin ageing is also characterized by a reduction of the epidermal thickness and by a flattening of the basal membrane.

Effects of solar ultraviolet radiation on engineered human skin equivalent containing both Langerhans cells and dermal dendritic cells.

Exposure of human skin to solar ultraviolet (UV) light induces local and systemic immune suppression. It is known that alterations of immune functions of Langerhans cells (LCs) and dermal dendritic cells (DDCs) mediate this phenomenon. The purpose of this study was to mimic in vitro the early UV-induced skin disruption to better understand the involvement of the skin micro-environment in triggering this immunosuppressive state.

Acellular mineral deposition in collagen-based biomaterials incubated in cell culture media.

Rapid developments in tissue engineering have renewed interest in biodegradable three-dimensional structures such as collagen-based biomaterials. Collagen matrices seeded in vitro with fibroblasts, osteoblasts, and chondrocytes can form tissues resembling skin, bone, and cartilage that could be used as functional substitutes for damaged tissues. Collagen is associated with both dystrophic calcification of collagenous implants and bone mineralization.

Cellular activity of osteoblasts in the presence of hydroxyapatite: an in vitro experiment.

The use of synthetic calcium phosphate as bone substitute calls for the knowledge of the influence on adjacent cells. Effects on monocytes, macrophages, synovial cells and fibroblasts have been largely described in vivo and in vitro but few data are available as concerns osteoblast responses. The present experiments tested the activity of MC3T3-E1, ROS 17/2.

The influence of calcium phosphate biomaterials on human bone cell activities. An in vitro approach.

An in vitro method is described to assess the influence of synthetic calcium phosphate powders on osteoblast activities. Human osteoblast cell cultures were established from iliac crest. MC3T3-E1, an established osteogenic cell line, was employed as a control.

Effects of synthetic calcium phosphates on the 3H-thymidine incorporation and alkaline phosphatase activity of human fibroblasts in culture.

Gingival fibroblasts were cultured with four different calcium phosphate minerals (hydroxyapatite, whitlockite, beta-tricalcium phosphate, and octocalcium phosphate). 3H-thymidine incorporation into DNA and alkaline phosphatase specific activity were determined after different incubation periods. As a consequence of the phagocytosis of calcium phosphates crystals, we pointed out, compared to control, a stimulation of the rate of 3H-thymidine incorporation and sharp decreases in alkaline phosphatase activity.

Chemical changes in hydroxyapatite biomaterial under in vivo and in vitro biological conditions.

The introduction of a synthetic calcium phosphate into a biological environment is likely to result in surface-mediated chemical events. On the basis of such an assessment, we studied the chemical changes occurring in the mineral after exposure of a synthetic hydroxyapatite ceramic to both in vivo (implantation in human) and in vitro (cell culture) conditions. A small amount of the material was phagocytized but the major remaining part behaved as a secondary nucleator as evidenced by the appearance of a newly formed mineral.

Hydroxyapatite biomaterial implanted in human periodontal defects: an histological and ultrastructural study.

The purpose of the present work was to study the response of human periodontium to hydroxyapatite biomaterial particles (180-200 microns). The biomaterial was implanted in two infra-osseous periodontal defects (two patients) after clearing of the granulation tissue. At two months post-surgery, biopsies were studied using light and electron microscopy.

Solution-mediated transformation of octacalcium phosphate (OCP) to apatite.

OCP crystals were hydrolyzed in solutions containing Ca2+, Mg2+, HPO4(2-), CO3(2-), F-, citrate or P2O7 ions. Products of hydrolysis were analyzed using scanning (SEM) and transmission (TEM) electron microscopy, infrared spectroscopy and x-ray diffraction. Results demonstrated that the OCP to Apatite (AP) transformation is influenced by: (1) types of ions in solution: inhibited by Mg2+, citrate or P2O7(4-); facilitated by F-, CO3(2-), HPO4(2-) or Ca2+ ions; (2) ionic concentrations; (3) solution pH; (4) OCP crystal size.

Scanning electron microscopy and electron probe microanalyses of the crystalline components of human and animal dental calculi.

A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components. This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed.

Transmission electron microscopy of the morphological relationship between fibroblasts and pulp calcifications in temporary teeth.

Calcifications found in the coronal pulps of primary teeth extracted in an 8-year-old child were studied by TEM. Different types of relationship were observed between fibroblasts and pulp calcifications: extension of cell processes towards calcifications, modelling of the cells upon calcifications, internalizing process of calcifications. Fibroblasts proved to be able to enclose small pulp calcifications within intracytoplasmic vesicles.

In vitro effects of calcium phosphate biomaterials on fibroblastic cell behavior.

The effect of synthetic granular hydroxyapatite (HAP) on cultured fibroblastic cells (L929, human bone and gingiva cells) was studied. Phagocytosis of HAP particles and resulting morphological cell changes were demonstrated by microscopic examinations. Cell counts and [3H]thymidine uptake indicated significant increases in cell proliferation and DNA synthesis.