Chain dynamics of human dermis by Thermostimulated currents: A tool for new markers of aging.

BACKGROUND/PURPOSE: The purpose of this clinical study was to identify dielectric markers to complete a previous thermal and vibrational study on the molecular and organizational changes in human dermis during intrinsic and extrinsic aging. METHODS: Sun-exposed and non-exposed skin biopsies were collected from 28 women devised in two groups (20-30 and ≥60 years old). The dielectric relaxation modes associated with localized and delocalized dynamics in the fresh and dehydrated state were determined by the Thermostimulated currents technique (TSC). RESULTS: Intrinsic and extrinsic aging induced significant evolution of some of the dielectric parameters of localized and delocalized dynamics of human skin. With photo-aging, freezable water forms a segregated phase in dermis and its dynamics is close to free water, what evidences the major role of extrinsic aging on water organization in human skin. Moreover, TSC indicators highlight the restriction of localized mobility with intrinsic aging due to glycation, and the cumulative effect of chronological aging and photo-exposition on the molecular mobility of the main structural proteins of the dermis at the mesoscopic scale. CONCLUSION: TSC is a well-suited technique to scan the molecular mobility of human skin. It can be uses as a relevant complement of vibrational and thermal characterization to follow human skin modifications with intrinsic and extrinsic aging.

Identification of ageing biomarkers in human dermis biopsies by thermal analysis (DSC) combined with Fourier transform infrared spectroscopy (FTIR/ATR).

BACKGROUND/PURPOSE: The purpose of this clinical study was to identify suitable biomarkers for a better understanding of the molecular and organizational changes in human dermis during intrinsic and extrinsic ageing. METHODS: Sun-exposed and non-exposed skin biopsies were collected from twenty-eight women devised in two groups (20-30 and ≥60 years old). The hydric organization and thermal transitions were determined by Differential Scanning Calorimetry (DSC). Fourier Transform Infrared spectroscopy (FTIR) was used to identify the absorption bands of the dermis and to quantify the different absorbance ratio. RESULTS: The amounts of total, freezable and unfreezable water were determined. A significant increasing amount of freezable water is evidenced in sun-exposed area skin of aged group compared with young group (P=.0126). Another significant effect of extrinsic ageing (P=.0489) is the drastic decrease of fibrillary collagen, the main protein component of dermis. The only significant effect of intrinsic ageing (P=.0184) is an increase of the heat-stable fraction of collagens in dermis. CONCLUSION: DSC and FTIR are well-suited techniques to characterize human skin, giving accurate results with a high reproducibility. The combination of these techniques is useful for a better understanding of human skin modifications with intrinsic and extrinsic ageing.

Conformational and thermal characterization of a synthetic peptidic fragment inspired from human tropoelastin: Signature of the amyloid fibers.

OBJECTIVES: This work deals with the conformational and thermal characterization of a synthetic peptide (S4) released during the proteolysis of human tropoelastin by the matrix metalloproteinase-12 that was shown to form amyloid-like fibres under certain conditions. MATERIALS AND METHODS: S4 peptides were synthesized by solid-phase methodology and aggregated in solution at 80°C. Fourier transform-infrared spectroscopy (FT-IR) was used to access the secondary structure. Thermal characterization was performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). RESULTS: The DSC study of the soluble linear peptide S4 in solution in TBS reveals the irreversible aggregation into amyloid fibres. FT-IR, DSC and TGA analyses performed on freeze-dried samples evidence differences between the linear peptide and its associated amyloid-like fibres, both on the conformation and the physical structure. When S4 peptides are aggregated, the prominent conformation scanned by FT-IR is the cross ß-structure, corresponding to TGA to an increase of the thermal stability. Moreover, the DSC thermograms of S4 fibres are characteristic of a highly ordered structure, in contrast to the DSC thermograms of S4 linear peptides, characteristic of an amorphous structure. Finally, the DSC analysis of differently hydrated S4 fibres brings to the fore the specific thermal answer of the wet interfaces of the cross ß-fibres. CONCLUSION: FT-IR and thermal techniques are well suited to evidence conformational and structural differences between the soluble peptide and its amyloid form.

Oral Health and Undernutrition in the Frail Elderly Persons.

INTRODUCTION: Although many studies associate a poor state of oral health with the risk of undernutrition in both the autonomous and dependent elderly, very few of them consider the frail elderly person. However, the identification of the frail elderly is one of major issues of modern geriatrics. It is at this stage that preventive strategies are the most effective against the risks of dependency. The main objective of our study is to explore the nature of the association between oral health and undernutrition in the frail elderly patient, and to identify the associated factors. MATERIALS AND METHODS: We have used the data of an observational transversal monocentric study, conducted among a population of patients hospitalized for frailty assessment at the Geriatric Frailty Clinic (G.F.C.) for Assessment of Frailty and Prevention of Disability. The enrolment site is the Cité de la Santé, at Toulouse University Hospital. Data were collected from January 25, 2016 February 2, 2018. The data collected sociodemographic characteristics, oral health (Oral Health Assessment Tool), nutritional status (Mini Nutritional Assessment), Body Mass Index, and weight loss according to Fried), frailty (Fried criteria), functional status (Mini Mental State Examination, Activity of Daily Living, Instrumental Activity of Daily Living, Geriatric Depression Scale-15), and behavior (tobacco and alcohol). RESULTS: We included 1,155 subjects with an average age of 81.9 years, including 65% women. Bivariate analysis indicated a statistically significant association (p<0.05) between a pathological state of oral health and undernutrition, particularly with regard to decay of natural teeth, pathologies of the tongue, gums and tissues, dry mouth, lack of oral cleanliness and presence of dental pain. Multivariate analysis adjusted for socio-demographic, behavioral and functional data confirmed some of these associations, notably between the item gum/mucous membrane and the decrease of the score (p<0.01); this same item and weight loss according to Fried (p<0.01), and the item tongue and weight loss (p<0.05). A statistically significant association appeared between the state of oral health and frailty (item tongue (p<0.01)). DISCUSSION: Our study shows a statistically significant association between a pathological state of oral health and nutrition disorders in the frail elderly person. This result confirms the hypothesis postulating that a poor state of oral health would be associated with nutritional disorders among the frail elderly. Our analysis also shows a statistically significant association between a deteriorated state of oral health and frailty. Tongue diseases here increase the risk of frailty for the patient. Our results are, however, limited and do not allow for an analysis of causal effect. It would be useful to complete our study by more refined analyses of risk factors, conducted on a larger sample, and with a follow-up patients over time. CONCLUSION: We show here the importance of targeting the frail population in order to screen for oral disease and refer patients for dental care. Ensuring oral health care of frail patients seems indispensable if they are to maintain not only a healthy nutritional state, but also a satisfactory general state of health, thus allowing for successful aging.

Oral Health and the Frail Elderly.

INTRODUCTION: The relationships between oral health conditions and frailty have rarely been explored. A systematic review of frailty components and oral health concluded that differences in study population endpoint criteria and study design cannot establish a relationship between frailty and oral health. OBJECTIVE: This study aims to describe the distribution of the OHAT (Oral Health Assessment Tool) score in a population of frail subjects and to assess associated parameters (age, socio-economic status, living conditions, education level, nutritional habits, cognitive functioning, autonomy). DESIGN: Cross-sectional observational study among patients referred to the Geriatric Frailty Clinic. MEASUREMENTS: 1314 patients participated in different standardized tests to evaluate their health status, cognitive and affective functioning, adaptation to usual daily activities, nutritional status, and oral health status. RESULTS: The risk of oral health deterioration was higher with the appearance of frailty: the OHAT increased significantly with the Fried Frailty Score (p<0.001). Physical performance and oral health were correlated (p<0.001). The OHAT score and the MNA (Mini Nutritional Assessment) score were significantly correlated: oral status seemed better for malnourished subjects (p<0.001). Dementia significantly increased the risk of an unhealthy oral status (p<0.001). There was no significant correlation between oral status and depression, just a trend. CONCLUSION: This pilot study establishes a relationship between the OHAT and Fried Frailty Criteria in a population of frail elderly. It must be expanded to follow the distribution of the different items composing the OHAT score (items assessing lips; tongue; gums and tissues; saliva; natural teeth; dentures; oral cleanliness; and dental pain) with different parameters (age, socio-economic status, living conditions, educational level, medical history, drug treatment, nutritional habits, cognitive functioning, disabilities and handicaps).

Dynamic mechanical properties of oral mucosa: Comparison with polymeric soft denture liners.

The purpose of this work was to characterize the viscoelastic behaviour of oral mucosa and compare it with the dynamic mechanical properties of different soft liners. For this purpose, a sample of pig oral mucosa and six commercialized soft liner samples have been investigated. A comparison was also carried with the first suitable hard rubber for dental prosthetics: vulcanite. Creep recovery (CR) and dynamic mechanical analysis (DMA) have been used to determine the mechanical modulus of oral mucosa and soft liners respectively. The Poisson ratio is used to compare mucosa bulk modulus and soft liner shear modulus. The biomechanical concept of conventional complete dentures needs a good adjustment of dynamic mechanical impedance between the base and oral mucosa. The viscoelastic mechanical property of the oral mucosa as a referent biopolymer has been confirmed in vitro. The modulus value, adjusted for old patients in physiological conditions, is in the order of 3 MPa. This study underlines the plasticization effect of absorbed water on the mechanical properties of the underlying tissue. This study allows us to define some characteristics of the most adapted biomaterial according to the clinical exigency. The required biomaterial must display the following properties: compatibility and chemical resistance with biological environment perpetuated mechanical properties during physiological conditions and clinical use, good adjustment of dynamic mechanical impedance with supporting mucosa and easy sample processing.