Linking the Mechanics of Chewing to Biology of the Junctional Epithelium.

The capacity of a tissue to continuously alter its phenotype lies at the heart of how an animal is able to quickly adapt to changes in environmental stimuli. Within tissues, differentiated cells are rigid and play a limited role in adapting to new environments; however, differentiated cells are replenished by stem cells that are defined by their phenotypic plasticity. Here we demonstrate that a Wnt-responsive stem cell niche in the junctional epithelium is responsible for the capability of this tissue to quickly adapt to changes in the physical consistency of a diet. Mechanical input from chewing is required to both establish and maintain this niche. Since the junctional epithelium directly attaches to the tooth surface via hemidesmosomes, a soft diet requires minimal mastication, and consequently, lower distortional strains are produced in the tissue. This reduced strain state is accompanied by reduced mitotic activity in both stem cells and their progeny, leading to tissue atrophy. The atrophied junctional epithelium exhibits suboptimal barrier functions, allowing the ingression of bacteria into the underlying connective tissues, which in turn trigger inflammation and mild alveolar bone loss. These data link the mechanics of chewing to the biology of tooth-supporting tissues, revealing how a stem cell niche is responsible for the remarkable adaptability of the junctional epithelium to different diets.

Expression of osteogenic factors in FasL-deficient calvarial cells.

During bone development, FasL acts not only through the traditional apoptotic mechanism regulating the amount of bone-resorbing osteoclasts, but there is also growing evidence about its effect on cell differentiation. Expression of osteoblastic factors was followed in non differentiated and differentiating primary calvarial cells obtained from FasL-deficient (gld) mice. The gld cells showed decreased expression of the key osteoblastic molecules osteocalcin (Ocn), osteopontin (Opn), and alkaline phosphatase (Alpl) in both groups. Notably, receptor activator of nuclear factor kappa-B ligand (Rankl) was unchanged in non-differentiated gld vs. wild type (wt) cells but decreased in differentiating gld cells. Osteoprotegerin (Opg) in the gld samples was increased in both groups. Opg vs. Rankl expression levels favored Opg in the case of non-differentiated cells but Rankl in differentiating ones. These results expand information on the involvement of FasL in non-apoptotic cell pathways related to osteoblastogenesis and consequently also osteoclastogenesis and pathologies such as osteoporosis.

New Caledonian crows plan for specific future tool use.

The ability to plan for future events is one of the defining features of human intelligence. Whether non-human animals can plan for specific future situations remains contentious: despite a sustained research effort over the last two decades, there is still no consensus on this question. Here, we show that New Caledonian crows can use tools to plan for specific future events. Crows learned a temporal sequence where they were (a) shown a baited apparatus, (b) 5 min later given a choice of five objects and (c) 10 min later given access to the apparatus. At test, these crows were presented with one of two tool-apparatus combinations. For each combination, the crows chose the right tool for the right future task, while ignoring previously useful tools and a low-value food item. This study establishes that planning for specific future tool use can evolve via convergent evolution, given that corvids and humans shared a common ancestor over 300 million years ago, and offers a route to mapping the planning capacities of animals.

[Reticular erythematous mucinosis-A special subtype of cutaneous lupus erythematosus?] / Retikuläre erythematöse Muzinose ­ Sonderform eines kutanen Lupus erythematodes?

Reticular erythematous mucinosis (REM syndrome) is a rare skin disease that predominantly affects women. It is clinically characterized by flat, partly reticular, irregularly configurated pale erythema located in the region of the central chest and upper back. The skin alterations are usually asymptomatic or associated with slight pruritus or burning. Extracutaneous diseases and involvement of internal organs do not occur in REM syndrome. Histopathological features include perivascular and periadnexal lymphocytic inflammatory infiltrates as well as increased deposition of mucin in the dermis. Due to the similar histology to lupus erythematosus (LE) tumidus, it is discussed whether REM syndrome can be assigned to the spectrum of cutaneous LE or can be assessed as a lupus-like disease. Moreover, both conditions respond well to treatment with hydroxychloroquine.

Saliva proteomic patterns in patients with molar incisor hypomineralization.

Molar incisor hypomineralization (MIH) is an endemic pediatric disease with an unclear pathogenesis. Considering that saliva controls enamel remineralization and that MIH is associated with higher saliva flow rate, we hypothesized that the protein composition of saliva is linked to disease. To test this, we enrolled 5 children aged 6-14 years with MIH showing at least one hypersensitive molar and 5 caries-free children without hypomineralization. Saliva samples were subjected to proteomic analysis followed by protein classification in to biological pathways. Among 618 salivary proteins identified with high confidence, 88 proteins were identified exclusively in MIH patients and 16 proteins in healthy controls only. Biological pathway analysis classified these 88 patient-only proteins to neutrophil-mediated adaptive immunity, the activation of the classical pathway of complement activation, extracellular matrix degradation, heme scavenging as well as glutathione -and drug metabolism. The 16 controls-only proteins were associated with adaptive immunity related to platelet degranulation and the lysosome. This report suggests that the proteaneous composition of saliva is affected in MIH patients, reflecting a catabolic environment which is linked to inflammation.

Management of congenital ichthyoses: European guidelines of care, part two.

These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016, and a consensus on the discussions. These guidelines summarize evidence and expert-based recommendations and intend to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part two, covering the management of complications and the particularities of some forms of congenital ichthyosis.

Management of congenital ichthyoses: European guidelines of care, part one.

These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016 and a consensus on the discussions. They summarize evidence and expert-based recommendations and are intended to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part one, covering topical therapies, systemic therapies, psychosocial management, communicating the diagnosis and genetic counselling.

Postrhinoplasty fibrotic syndrome.

BACKGROUND: Over the years there have been numerous anecdotal reports of nasal tip enlargement and loss of tip definition post rhinoplasty. Subsequent revisionary procedures not only failed to reduce the tip size but aggravated the problem causing an even larger and less defined nasal tip. The final result was often worse than the preop condition and uncorrectable. METHOD/RESULTS: Six patients who demonstrated an aggravation of the postop result with subsequent revisionary or secondary surgeries were evaluated to find common causes or circumstances. All patients had 1) worsening of nasal tip result with subsequent procedures, e. g., nasal tip enlargement and/or loss of tip definition with subsequent procedures 2) exhibited substantial postop edema at one or more surgeries and 3) extensive subcutaneous fibrous tissue noted at revisionary procedures. CONCLUSIONS: The nasal scenario described is referred to as postrhinoplasty fibrotic syndrome. It is recommended that if revision surgery is necessary by a surgeon, the scale of the surgery should be smaller than that of the primary operation. If yet another revision is necessary that surgery should be of an even smaller scale than the prior surgery. Augmentation rather than reduction rhinoplasty is clearly a better approach. With the surgical philosophy of smaller and/or less surgery with each revision (should it be necessary) the irreversible condition of postrhinoplasty fibrotic syndrome should be avoidable.

Free energy profiles for two ubiquitous damaging agents: methylation and hydroxylation of guanine in B-DNA.

DNA methylation and hydroxylation are two ubiquitous reactions in DNA damage induction, yet insights are scarce concerning the free energy of activation within B-DNA. We resort to multiscale simulations to investigate the attack of a hydroxyl radical and of the primary diazonium onto a guanine embedded in a solvated dodecamer. Reaction free energy profiles characterize two strongly exergonic processes, yet allow unprecedented quantification of the barrier towards this damage reaction, not higher than 6 kcal mol-1 and sometimes inexistent, and of the exergonicities. In the case of the [G(C8)-OH]˙ intermediate, we challenge the functional dependence of such simulations: recently-proposed functionals, such as M06-2X and LC-BLYP, agree on a ∼4 kcal mol-1 barrier, whereas the hybrid GGA B3LYP functional predicts a barrier-less pathway. In the long term, multiscale approaches can help build up a unified panorama of DNA lesion induction. These results stress the importance of DFT/MM-MD simulations involving new functionals towards the sound modelling of biomolecule damage even in the ground state.

Difference in release kinetics of unwashed and washed platelet-released supernatants from bone substitute materials: the impact of platelet preparation modalities.

BACKGROUND AND OBJECTIVE: In regenerative dentistry, platelet preparations are applied to stimulate bone healing and periodontal regeneration. Here, we pursue a strategy where bone substitutes are used as carriers for platelet-released supernatants. The mitogenic capacity and release kinetics of loaded bone substitutes were assessed. MATERIAL AND METHODS: Platelet-released supernatants of washed platelets (washed PRS) and platelet-released supernatants of unwashed platelets (unwashed PRS) were lyophilized onto the bone substitutes deproteinized bovine bone mineral, hydroxyapatite and ß-tricalcium phosphate. Scanning electron microscopy images were taken. Supernatants of bone substitutes were collected at hours 1, 3, 6, 24, and 48 and medium was replaced. We evaluated the protein content with the bicinchoninic acid assay and the effect on proliferation using bioassays with human periodontal fibroblasts. Release of growth factors from the loaded bone substitutes was measured based on the platelet-derived growth factor isoform (PDGF-BB) and thrombin immunoassays. Furthermore, we assessed DNA and RNA content of washed PRS and unwashed PRS. RESULTS: Unwashed PRS showed higher total protein concentrations than washed PRS, while the concentration of PDGF-BB, thrombin, DNA, RNA and their mitogenic effect was not significantly different. The bone substitute materials adsorbed protein over time but no significant changes in overall appearance was found. Supernatants collected from unwashed PRS-loaded bone substitute after 1 h induced a potent mitogenic response in periodontal fibroblasts. This pro-mitogenic capacity of the supernatants decreased over the observation period. Supernatants of washed PRS-loaded bone substitutes did not induce a substantial mitogenic effect. Levels of PDGF-BB, thrombin and protein were higher in supernatants of unwashed PRS-loaded bone substitutes than of washed PRS-loaded bone substitutes. CONCLUSION: Bone substitutes loaded with unwashed PRS, but not bone substitutes loaded with washed PRS show continuously declining release kinetics. These data suggest that plasma components in platelet preparations can modify the release kinetics profile.

Morphological alterations in two siblings with autosomal recessive congenital ichthyosis associated with CYP4F22 mutations.

Autosomal recessive congenital ichthyosis (ARCI) caused by mutations in CYP4F22 is very rare. CyP4F22, a protein of the cytochrome-P450 family 4, encodes an epidermal ω-hydroxylase decisive in the formation of acylceramides, which is hypothesized to be crucial for skin-barrier function. We report a girl with consanguineous parents presenting as collodion baby with contractures of the great joints and palmoplantar hyperlinearity. In the course of the disease she developed fine scaling of the skin with erythroderma, the latter disappearing until the age of 6 months. Her sister showed a generalized fine-scaling phenotype, and, interestingly, was born without a collodion membrane. The analysis of all known candidate genes for ARCI in parallel with a next-generation sequencing approach using a newly designed dermatogenetics gene panel revealed a previously unknown homozygous splice-site mutation c.549+5G>C in CYP4F22 in both girls, confirming the diagnosis of ARCI. Ultrastructural analysis by transmission electron microscopy in both patients showed epidermal hyperplasia, orthohyperkeratosis with persistence of corneodesmosomes into the outer stratum corneum layers, fragmented and disorganized lamellar lipid bilayers, which could be ascribed to inhomogeneous lamellar body secretion, as well as lamellar body and lipid entombment in the corneocytes. These findings correlated with increased transepidermal water loss on the functional level. For the first time, we report a collodion baby phenotype and epidermal barrier impairment in CyP4F22-deficient epidermis at both the ultrastructural and functional level, and corroborate the importance of CyP4F22 for epidermal maturation and barrier function.

[Position paper on medication-related osteonecrosis of the jaw (MRONJ)]. / Positionspapier zur medikamentenassoziierten Osteonekrose des Kiefers (MRONJ).

It is now 12 years since the first article on medication-related osteonecrosis of the jaw (MRONJ) was reported in 2003. The recognition of MRONJ is still inconsistent between physicians and dentists but it is without doubt a severe disease with impairment of oral health-related quality of life. This position paper was developed by three Austrian societies for dentists, oral surgeons and osteologists involved in this topic. This update contains amendments on the incidence, pathophysiology, diagnosis, staging and treatment and provides recommendations for management based on a multidisciplinary international consensus. The MRONJ can be a medication-related side effect of treatment of malignant and benign bone diseases with bisphosphonates (Bp), bevacizumab and denosumab (Dmab) as antiresorptive therapy. The incidence of MRONJ is highest in the oncology patient population (range 1-15 %), where high doses of these medications are used at frequent intervals. In the osteoporosis patient population, the incidence of MRONJ is estimated to be 0.001-0.01 %, marginally higher than the incidence in the general population (< 0.001 %). Other risk factors for MRONJ include glucocorticoid use, maxillary or mandibular bone surgery, poor oral hygiene, chronic inflammation, diabetes mellitus, ill-fitting dentures as well as other drugs, including antiangiogenic agents. Prevention strategies for MRONJ include elimination or stabilization of oral disease prior to initiation of antiresorptive agents, as well as maintenance of good oral hygiene. In those patients at high risk for the development of MRONJ, including cancer patients receiving high-dose BP or Dmab therapy, consideration should be given to withholding antiresorptive therapy following extensive oral surgery until the surgical site heals with mature mucosal coverage. Management of MRONJ is based on the stage of the disease, extent of the lesions and the presence of contributing drug therapy and comorbidity. Conservative therapy includes topical antibiotic oral rinses and systemic antibiotic therapy. Early data have suggested enhanced osseous wound healing with teriparatide in those patients without contraindications for its use. The MRONJ related to denosumab may resolve more quickly with a drug holiday than MRONJ related to bisphosphonates. Localized surgical debridement is indicated in advanced nonresponsive disease and has proven successful. More invasive surgical techniques are becoming increasingly more important. Prevention is the key for the management of MRONJ. This requires a close teamwork for the treating physician and the dentist. It is necessary that this information is disseminated to other relevant health care professionals and organizations.

Differential inflammatory response of dental pulp explants and fibroblasts to saliva.

AIM: To investigate the inflammatory response of dental pulp fibroblasts and the respective explants to whole saliva. METHODOLOGY: Explants from human and porcine dental pulp tissue and isolated dental pulp fibroblasts were used to investigate the inflammatory response to sterile saliva. Cytokine and chemokine expression was assessed by RT-PCR. Western blot analysis and pharmacologic inhibitors were used to determine the involvement of signalling pathways. RESULTS: Dental pulp explants of human and porcine origin exposed to human saliva exhibited no major changes of IL-6 and IL-8 mRNA expression (P > 0.05). In contrast, isolated porcine and human dental pulp fibroblasts, when stimulated with human saliva, exhibited a vastly increased expression of IL-6 and IL-8 mRNA (P < 0.05). In pulp fibroblasts, saliva also increased the expression of other cytokines and chemokines via activation of NFkappaB, ERK and p38 signalling. Notably, a significantly reduced inflammatory response was elicited when pulp fibroblasts were transiently exposed to saliva. CONCLUSIONS: Saliva has a potential impact on inflammation of dental pulp fibroblasts in vitro but not when cells are embedded in the intrinsic extracellular matrix of the explant tissue.

Thermal processing of bone: in vitro response of mesenchymal cells to bone-conditioned medium.

The autoclaving, pasteurization, and freezing of bone grafts to remove bacteria and viruses, and for preservation, respectively, is considered to alter biological properties during graft consolidation. Fresh bone grafts release paracrine-like signals that are considered to support tissue regeneration. However, the impact of the autoclaving, pasteurization, and freezing of bone grafts on paracrine signals remains unknown. Therefore, conditioned medium was prepared from porcine cortical bone chips that had undergone thermal processing. The biological properties of the bone-conditioned medium were assessed by examining the changes in expression of target genes in oral fibroblasts. The data showed that conditioned medium obtained from bone chips that had undergone pasteurization and freezing changed the expression of adrenomedullin, pentraxin 3, BTB/POZ domain-containing protein 11, interleukin 11, NADPH oxidase 4, and proteoglycan 4 by at least five-fold in oral fibroblasts. Bone-conditioned medium obtained from autoclaved bone chips, however, failed to change the expression of the respective genes. Also, when bone-conditioned medium was prepared from fresh bone chips, autoclaving blocked the capacity of bone-conditioned medium to modulate gene expression. These in vitro results suggest that pasteurization and freezing of bone grafts preserve the release of biologically active paracrine signals, but autoclaving does not.