Combining elemental and immunochemical analyses to characterize diagenetic alteration patterns in ancient skeletal remains.

Bones and teeth are biological archives, but their structure and composition are subjected to alteration overtime due to biological and chemical degradation postmortem, influenced by burial environment and conditions. Nevertheless, organic fraction preservation is mandatory for several archeometric analyses and applications. The mutual protection between biomineral and organic fractions in bones and teeth may lead to a limited diagenetic alteration, promoting a better conservation of the organic fraction. However, the correlation between elemental variations and the presence of organic materials (e.g., collagen) in the same specimen is still unclear. To fill this gap, chemiluminescent (CL) immunochemical imaging analysis has been applied for the first time for collagen localization. Then, Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and CL imaging were combined to investigate the correlation between elemental (i.e., REE, U, Sr, Ba) and collagen distribution. Teeth and bones from various archeological contexts, chronological periods, and characterized by different collagen content were analyzed. Immunochemical analysis revealed a heterogeneous distribution of collagen, especially in highly degraded samples. Subsequently, LA-ICP-MS showed a correlation between the presence of uranium and rare earth elements and areas with low amount of collagen. The innovative integration between the two methods permitted to clarify the mutual relation between elemental variation and collagen preservation overtime, thus contributing to unravel the effects of diagenetic alteration in bones and teeth.

Thr92Ala polymorphism in the type 2 deiodinase gene: an evolutionary perspective.

PURPOSE: In the past, a role of thyroid hormones in human evolution has been hypothesized. T3, the metabolically active form, derives from extrathyroidal conversion of T4 by deionidase 2 (D2) enzyme encoded by DIO2 gene. In thyroid-deficient patients, decreased levels of free T3 have been associated with the polymorphism rs225014 A/G in DIO2, which causes the substitution of Threonine with Alanine (p.Thr92Ala) at protein level. METHODS: We compared DNA and protein sequences of D2 from archaic human subspecies with those of contemporary humans. RESULTS: Neanderthals and Denisovans displayed only the G allele at the rs225014 polymorphism, which encodes for an Alanine on the amino acid level. These data suggest that these hominines were homozygous for the Ala amino acid. These arcaic humans often lived in condition of iodine deficiency and thus, defective mechanisms of T3 biosynthesis could be life threatining. A reduced D2 activity is likely to cause decreased T3 levels, which could be critical for those individuals. Neanderthals and Denisovans were hunters/gatherers, and their diet was mainly based on the consumption of meat, with a low intake of carbohydrates. The need for circulating T3 is reduced at such alimentary conditions. On the basis of our genome comparisons the A allele, corresponding to Threonine and associated with higher levels of circulating T3 in thyroid-deficient patients, appeared for the first time during evolution in Anatomically Modern Humans during the Upper Pleistocene and has been conserved during the Neolithic age. With the advent of agriculture and herding, individuals carrying A allele might have a higher probability for surviving and reproducing. Thus, the variant was positively selected during the evolution. CONCLUSION: Here we present an evolutionary perspective for p.Thr92Ala variant of D2 from Neanderthals to Anatomically Modern Humans.

Functionalization of PVDF membranes with carbohydrate derivates for the controlled delivery of chlorhexidin.

Maltodextrin (MX) was fixed onto PVDF membranes in order to create a drug delivery Guided Tissue Regeneration (GTR) device with controlled drug delivery properties. PVDF microporous membranes were treated by a mixture of MX and citric acid, resulting to an 18 wt% increase of the supports. MX grafted membrane could capture 103 mg/g chlorhexidin digluconate (DigCHX) instead of 1mg/g for a virgin membrane. A neutralization step was performed before the biological tests. Viability tests confirmed the non-toxicity of the MX polymer coating after neutralisation. In vitro release test in human plasma, and microbiological tests showed that membranes grafted with MX were more performing compared to virgin and beta-CD grafted membranes. The antimicrobial activity was effective during more than 72 h.

Vascular prostheses with controlled release of antibiotics Part 2. In vitro biological evaluation of vascular prostheses treated by cyclodextrins.

Viability tests by the colony forming method show no toxicity for all CDs (beta-CD, gamma-CD, HPbeta-CD and HPgamma-CD) and their associated polymer. A survival rate of 100% is observed for all CDs at high concentration 400 ppm. Proliferation tests revealed a low proliferation of L132 cells on grafted vascular prostheses and untreated prostheses and good proliferation on Melinex (film form of PET). A proliferation of 17% is observed after 3 days of incubation and decrease at 4% after 6 days on prostheses. Melinex exhibits a proliferation rate as the controls. Vitality tests confirm proliferation tests and show a good vitality of cells even for low cell amounts. From these experiments it becomes obvious that the decreasing proliferation rate is not a cytotoxic effect but is due to the chemical and/or physical surface characteristics. A similar result is obtained for cell adhesion kinetics between grafted vascular prostheses and control. After 2 h adhesion, a lower adhesion is observed on untreated prostheses. Theses results were confirmed by immunochemistry and morphology tests. This cell adhesion inhibiting effect of the PET prostheses contributes to a better "survival" of vascular prostheses without secondary obstruction or stenosis.

Vascular prostheses with controlled release of antibiotics Part 1: Surface modification with cyclodextrins of PET prostheses.

Vascular prostheses were functionalised with the aim to obtain a slow release of antibiotics in order to reduce postoperative infections. The original process that we present in this paper is based on the use of a family of cage molecules named cyclodextrins (CD). These compounds have the ability to form reversible inclusion complexes with drugs such as antibiotics. The aim of this work was to graft CD onto the prosthesis, so that an antibiotic can be bound on it by this inclusion phenomenon, and then be progressively released over a prolonged period by a complex dissociation mechanism. This paper presents the first part of this research program and concerns mainly the study of the functionalization parameters. It presents surface characterization results of the modified prostheses. The PET prostheses were immersed into a solution containing a cross linking agent, cyclodextrins (beta-CD, gamma-CD, HP-beta-CD and HP-gamma-CD) and a catalyst and were padded. Grafting occurred by the mean of a thermofixation step at a temperature comprised between 140 and 180 degrees C. It was observed that the support was permanently modified when the CD polymer that coated the fibres resisted to the final washing process. Grafting rates of 12 wt% in CD polymer could be reached. It was also observed that the fibre coating reaction induced an increase of the permeability of the grafts.

Improved drug delivery properties of PVDF membranes functionalized with beta-cyclodextrin--application to guided tissue regeneration in periodontology.

The purpose of this study was to develop a membrane for guided tissue regeneration applicable in periodontology that could release antimicrobial agent during the healing period. Our strategy consisted to graft beta-cyclodextrin (beta-CD), a molecule that is known to form inclusion complexes with a large variety of drugs, onto PVDF membranes. Grafting occurred by using citric acid that provoked a crosslinking reaction of beta-CD, and the resulting polymer was imprisoned into the porous structure of the PVDF membrane. The reaction produced a weight increase of the membrane, the range of which depended on the temperature and on the time of curing applied in the process. The biological behavior of the membranes evaluated by proliferation and vitality tests showed good proliferation and improved activity of L132 epithelial cells on the raw and on the grafted membranes. Doxycyclin (DOX) and chlorhexidine (CHX) were used as antimicrobial agents. Their inclusion into the beta-CD cavity in aqueous solutions was confirmed by NMR spectroscopy. After the impregnation of the membranes with DOX and CHX, their release was studied in vitro in batch type experiments and measured by UV spectrophotometry. Low amounts of DOX and CHX were delivered from the raw membranes within the first few hours of tests. Grafted membranes, however, delivered DOX and CHX in larger quantities within 24 h and 10 days respectively.

[Periodontal diseases, tobacco and pregnancy]. / Maladies parodontales, tabac et grossesse.

This review summarizes the impact of tobacco on the periodontium of pregnant women and the effects of periodontal diseases combined with tobacco on the pregnancy. Periodontal diseases (gingivitis and periodontitis) are gram-negative anaerobic infections. Smokers are 2-7 times more likely to develop periodontal disease than non-smokers. Tobacco, an environmental factor, undermines the host response and may facilitate the development and progression of periodontal disease. Recent epidemiological studies suggest that maternal periodontal diseases would be a risk factor of pre-term deliveries or pre-term low birth weight (PLBW). Cigarette smoking during pregnancy leads to peri-natal morbidity and mortality and it is associated with reduced birth-weight. Tobacco during pregnancy also amplifies the risk of PLBW directly and via periodontal diseases. This article highlights the etio-pathogenic interrelations between periodontal diseases and tobacco as risk factors of PLBW. The blood dissemination of periodontal bacteria and the effects of cytokines like TNF-alpha, Il-1, produced during periodontal infections could explain these obstetrical adverse events. The concept of diagnosing and treating a periodontal disease in a pregnant woman to minimizes the deleterious effects of this infection on systemic conditions represents an unprecedented challenge. Moreover, periodontist have the opportunity to take part in smoking cessation program for pregnant women.