Reintegration of freshly extracted healthy teeth is very successful, most likely due to the regenerative capacity of their roots’ residual periodontal ligament (PDL). We hypothesised that in vitro cultures of the consecutive slices of a sectioned root will represent the entity of PDL cell types engaged in tooth-sided reintegration. For confirmation, apex and pulp from human premolars were removed and roots cut into 6 to 9 about 1 mm thick slices. These were immobilised to separate wells and cultured for 20 days, under daily inspection for the initiation of cell outgrowth (ICO). ICO and the distribution of vital slices along, the cell growth around as well as the expansion of outgrown cells off the root axes after 20 days were displayed for each tooth as 3D-like profiles. Of the 81 slices from 11 teeth, 55 showed ICO; 64% within one week and 96% within two weeks. Such dynamics compare to the early (day 2–5) and the intermediate (day 9–14) integration phase reported for PDL cells in vivo. Experimental phase contrast images of a single slice showed at ICO few fibroblast- and stem/progenitor- like cells. Four and five days later at the same site cells had grown in number and changed in shape and space over time. This exploratory study indicates that in root slice cultures PDL cells behave similarly to those during reintegration in vivo. It favours our hypothesis, which is now to be adequately verified. Eventually, the model may facilitate the identification of outgrowing cells and cellular changes over time, as triggered by tissue rupture. It may further allow for emulating cellular interactions between the root surface and alveolar bone or engineered constructs, natural or engineered scaffolds, or other tissue, in an in vivo-like situation.

Tape stripping in conjunction with scanning Raman microscopy was used for assessing the lateral and vertical distribution of an organic particulate UV filter, methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), in a sunscreen formulation. On the volar forearms of three volunteers, 1 mg cm(-2) formulation containing 10% MBBT was applied, and the average amount of MBBT was measured by Raman scanning microscopy in 15 consecutive tape strippings. The recovery of MBBT was 91.1% with 30.2% localizing on the skin surface (first strip), 42.5% in the upper stratum corneum (strips 2-5) and from 3.6 down to 0.8% in each of the 10 consecutive layers. The concentration of surface deposits of MBBT differed by a factor of 300 between folds, furrows and pores on the one hand and the interjacent ridges on the other hand. Seventy-five per cent of the applied particles occupied a fifth of the evaluated area - where concentrating in folds and furrows - as was confirmed by 3-D reconstruction. On interjacent ridges, 8.6% of MBBT distributed as very thin films preferentially. MBBT localized at sites not connected with the surface, such as in truncated pores or as potentially penetrated material amounted to 0.06% or to a twentieth of the 1.4% found in the lowest skin strippings. Scanning Raman microscopy in combination with tape stripping documented the lateral and vertical distribution quantitatively and at cellular (12.5 μm) lateral resolution. Our results confirmed an earlier report on the vertical distribution of organic particles applied to skin and was in line with similar reports on TiO(2) distribution.

Photo-instability of common UV-filters is a well documented phenomenon. This study develops a method for concomitant measurement of photostability and photo-induced ROS generation in cosmetic formulations. Oil-in-water formulations containing three common UV filters (OMC, BMDBM, EHT), individually or combined, were further supplemented with phosphatidylcholine and exposed to UVA. All filters show spectral decrease after UVA exposure. OMC and EHT do not induce significant lipid-peroxidation (as measured by TBARS production) while BMDBM does. In the latter case, this is reduced when BMDBM is combined with OMC but not with EHT. Neither OMC nor EHT stabilize BMDBM with respect to loss of absorbance. ROS-generation assessed via TBARS formation was supported by EPR experiments. The UV-induced changes in UV-filter performance, as monitored in the model formulations and in commercial sunscreens, demonstrate that this is a simple and effective method for stability assessment of sunscreen filters under conditions of use.

We lack comparative data on sunscreens with comparable sun protection factors (SPFs), but with different levels of UVA protection, especially against cumulative erythema from repeated suberythemal exposure. Thus, we compared the protection from cumulative sunburn with two sunscreens labeled SPF 6, but with different UVR-absorbing properties, one that absorbs the UVB waveband and the other that absorbs UVB+UVA wavebands. We simulated sunlight typical of temperate latitudes to expose skin daily to suberythemal doses for 13 consecutive days. The study population consisted of eight fair-skinned sun-sensitive healthy young adults. Erythema was assessed by eye and objectively, and the SPF of each sunscreen was modeled with changes in solar UVR with time of day and latitude. The broad-spectrum sunscreen gave much better protection against cumulative erythema than the UVB sunscreen. The explanation for this is that UVA makes a greater contribution toward sunburn at temperate latitudes than under the laboratory conditions in which SPF is tested and assigned. The data support the current trend toward broad-spectrum sunscreen protection. They also show that labeled SPF is much more reliable with broad-spectrum sunscreens because SPF with primarily UVB sunscreens is dependent on time of day and latitude.

Objectives To investigate the effects of interleukin 1 beta (IL1 beta) treatment on the Notch1/Hes1 pathway in chondrocytes in vitro.Methods Mouse articular chondrocytes in primary culture were challenged with IL1 beta, alone or combined with Notch1 and IL1 beta pathway inhibitors. Notch1 and Hes1 expressions were investigated by immunocytochemistry, western blot and real-time quantitative (q) PCR. IL1 beta-responsive genes were assessed by real-time qPCR and a specific siRNA against Hes1 was used to identify Hes1 target genes.Results Notch1 labelling remained nuclear and stable in intensity irrespective of treatment, suggesting a steady state activation of this pathway in our model. IL1 beta transiently increased Hes1 mRNA (2.5-fold) and protein expression in treated versus naive chondrocytes. Hes1 mRNA level then decreased below control and its cyclic pattern of expression was lost. This was associated with nuclear translocation of the cytoplasmic Hes1 protein. IL1 beta induced increase in Hes1 mRNA was transcriptional, occurred through nuclear factor (NF)kappa B activation and appeared to be associated with downregulation by its own protein. Hes1 induction was insensitive to the gamma-secretase inhibitor N-(N-(3,5-difluorophenacetyl)l-alanyl)-S-phenylglycine t-butyl ester (DAPT), which suggested its independence from novel Notch1 activation. Hes1 expression was efficiently silenced by a specific siRNA. This experiment revealed that Hes1 did not mediate IL1 beta-induced downregulation of Sox9, type II collagen and aggrecan transcription but mediated IL1 beta induction of matrix metalloproteinase (MMP) 13 and ADAM metallopeptidase with thrombospondin type 1 motif, 5 (ADAMTS5). The Hes1-related repressor Hey1 was expressed at a very low level and was not inducible by IL1 beta.Conclusion Hes1 is a novel IL1 beta target gene in chondrocytes which influences a discrete subset of genes linked to cartilage matrix remodelling and/or degradation.

The pathological changes in osteoarthritis—a degenerative joint disease prevalent among older people—start at the molecular scale and spread to the higher levels of the architecture of articular cartilage to cause progressive and irreversible structural and functional damage. At present, there are no treatments to cure or attenuate the degradation of cartilage. Early detection and the ability to monitor the progression of osteoarthritis are therefore important for developing effective therapies. Here, we show that indentation-type atomic force microscopy can monitor age-related morphological and biomechanical changes in the hips of normal and osteoarthritic mice. Early damage in the cartilage of osteoarthritic patients undergoing hip or knee replacements could similarly be detected using this method. Changes due to aging and osteoarthritis are clearly depicted at the nanometre scale well before morphological changes can be observed using current diagnostic methods. Indentation-type atomic force microscopy may potentially be developed into a minimally invasive arthroscopic tool to diagnose the early onset of osteoarthritis in situ .

Clinical experience indicates that the surface architecture of dental implants has an important impact on their integration. This has been related to the finding that differentially treated substrates can modulate the expression of osteogenic markers in various bone-related cell lines and primary cells. Here, we investigated the influence of surface architecture on the differentiation of human mesenchymal progenitor cells (HMPC) from adult bone marrow, i. e. the cells likely involved in initial bone synthesis at the bone-implant interface. Cells were seeded on machine surfaced (MS) or sandblasted/acid etched (SE) titanium discs in agarose-coated dishes, and on polystyrene (PS) controls. On all substrates cell densities did not change between days 7 and 14. Cell numbers were higher on SE, likely due to increased attachment to the rougher material. Alkaline phosphatase activity (ALP) was similar on all substrates, whereas mRNA expression of bone sialoprotein (BSP) at day 14 was about tenfold higher on SE (p < 0.05%). The SE-related increase of BSP in progenitor cells indicates an earlier differentiation of immigrated cells and could thus explain earlier implant integration and shorter time to functional loading observed in the clinic. The in vitro model and BSP quantification could be used to screen for changes in osteogenic cell differentiation induced by specific implant surfaces, with potential relevance on the prediction of bone-implant integration.

Efficient UV-absorbing molecules are designed to protect against UV-light over-exposure. However, upon UV exposure they may change spectral performance or act as photooxidants via generation of free radicals and reactive oxygen species alone or in combination with others. Therefore, information about their photointegrity which comprises (i) stable absorbance and (ii) absence of UV-induced molecular breakdown, is fundamental. In this study, seven commonly used UV-A, UV-B and broad spectrum UV-AB filters and their combinations, were incorporated into phosphatidylcholine (PC)-based liposomes and exposed to UV-A (275kJ/m2). Spectral integrity, evaluated by recording UV-absorbance spectra of the extracted filter molecules and molecular integrity, assessed indirectly via quantification of UV-A induced PC peroxidation, revealed that spectral stability of filter molecules alone or in combination (e.g. trianilino p-carboxyethylhexyl triazine, EHT plus ethylhexyl p-methoxycinnamate, OMC) does not necessarily imply absence of radical generation and that spectral lability does not necessarily have to lead to radical generation and molecular decay (e.g. OMC). This simple system capable of discriminating between essentially photostable and photounstable UV-absorbing molecules alone and in mixtures, might be useful for determining the influence of UV-protection as well as of photostability of UV-absorbers with regard to UV-induced genotoxic/phototoxic and photoageing-related, radical-based processes.