Magneto-elastic properties of a spin crossover membrane deposited on a deformable substrate.

Spin-crossover (SCO) solids have been studied for several years due to their fascinating physical properties and their potential applications as optical switches and reversible high-density memories for information storage. Through this article, we will examine in details the effects of substrate's lattice parameters, on a deformable spin crossover membrane, simulated using an electro-elastic model taking into account the volume change at the transition. The molecules of the membrane can be either in the low spin state (LS) or the high spin state (HS), while those of the substrate are electronically neutral. Magnetic properties of the SCO membrane and the pressure distribution as a function of the lattice parameter of the substrate have been investigated. We demonstrated that the thermally induced first-order spin transition is significantly affected by the structural properties of the substrate, where a rise in the lattice parameter of the latter lowers the transition temperature and reduces the width of the thermal hysteresis loop. The investigations on the spatiotemporal aspects of the spin transition in the membrane demonstrates that the nucleation and growth processes are sensitive to the structural properties of the elastic misfit between the substrate and the SCO membrane.

Laboratory Studies of Nonlinear Optical Signals for Caries Detection.

Multiphoton confocal microscopy and nonlinear spectroscopy are used to investigate the caries process in dentin. Although dentin is a major calcified tissue of the teeth, its organic phase comprises type I collagen fibers. Caries drive dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique: the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to 1-photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal-to-noise ratio is improved significantly. The method has been used to follow pathologic processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy, we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during the tooth caries process, and we show that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on the caries process, specifically on the degradation of the organic matrix of dentin. The goal is to bring these nonlinear optical signals to clinical application for caries diagnosis.

A preliminary study of a new endodontic irrigation system: Clean Jet Endo.

The purpose of the present study was to assess the irrigant penetration and cleaning ability of a new irrigation system, the Clean Jet Endo (Produits Dentaires SA, Switzerland) in comparison to conventional irrigation followed or not by sonic activation. Irrigant penetration was evaluated on resin blocks simulators by measuring the methylene blue absorbance thanks to a UV/visible spectrophotometer and cleaning ability was assessed in an ex vivo experiment according to the debris score in an artificial canal extension before and after the final irrigation protocol. A statistical analysis was carried out in order to highlight the significant differences between the irrigation techniques. Clean Jet Endo permitted to better eliminate the methylene blue into the simulated canals. A significant difference between the 2 techniques was observed in the middle third (p = 0.005) as well as in the apical third (p < 0.2). An additional microscope observation (16X) confirmed that Clean Jet Endo@ usage led to a better penetration of irrigant within the lateral canals of the simulators. Likewise, this irrigating system permitted to better eliminate the debris in the lateral groove than the other techniques. In conclusion, our findings implied the potential of this new irrigation system to enhance root canal debridement and disinfection.

Properties of the low-spin high-spin interface during the relaxation of spin-crossover materials, investigated through an electro-elastic model.

The present work is devoted to the spatio-temporal investigations of spin-crossover lattices during their thermal relaxation from high- to low-spin state. The analysis is performed using Monte Carlo simulations on a distortable 2D lattice the sites of which are occupied by high-spin (HS) or low-spin (LS) atoms. The lattice is circular in shape and the HS to LS transformation results in single domain nucleation followed by growth and propagation processes. The evolution of the LS:HS interface is monitored during the relaxation process, through the mapping of spin states, displacement fields, local stresses, and elastic energy. The results show a curved interface, the curvature of which is reversed at the mid-transformation. The local stresses and elastic energy peak at the vicinity of the HS:LS interface, with sizeable dependence upon the position along the front line which evidences the edge effects.

Is early enteral nutrition dangerous in acute non surgical complicated diverticulitis? About 25 patients fed with oral fiber free energetic liquid diet.

BACKGROUND AND STUDY AIMS: Complicated Acute Colonic Diverticulitis (ACD) is usually treated by parenteral way thus keeping the bowel at rest. To date there are no clear recommendations regarding the route of nutrition administration. We study the safety of early feeding by oral energetic fiber-free liquid diet in non-surgical complicated ACD patients. PATIENTS AND METHODS: From February 2008 to October 2011, 25 patients were admitted with complicated ACD and took part in this prospective study. Surgical and medical assessments were performed at admission. Initial treatment was given with perfusion, intravenous antibiotics and hydric diet. Within 72 hours of admission, antibiotic therapy was switched to oral administration for 5 up to 15 days depending on the progression of the disease. At the same time the patient received oral liquid fiber-free feeding. Solid but fiber-free diet was introduced 24h hours before discharge. RESULTS: 25 cases of ACD were complicated with covered perforation and/or abscess. Mean hospitalisation time was 10A.4 days. 23 cases had good recovery and discharged, while 1 case progressed to colonic stenosis during hospitalisation, requiring a sigmoidectomy with a one-time anastomosis with good recovery. One patient relapsed his abscess during hospitalisation despite CT guided drainage and required sigmoidectomy with transient ileostomy. The mean daily treatment and nutrition cost for the non-surgical 23 patients was 30 euros. CONCLUSIONS: Early enteral nutrition in complicated ACD is feasible, not harmful, and reduce both, mean hospitalization time and treatment cost. Further studies comparing enteral with parenteral nutrition are necessary to confirm our hypothesis.

[Association between variants of lipoprotein lipase and coronary heart disease in a Tunisian population]. / Association entre des variations de la lipoprotéine lipase et la maladie coronarienne dans une population tunisienne.

OBJECTIVE: Coronary artery disease (CAD) is a complex multifactorial disease due to the interaction of multiple genes variations and environmental factors. Genetic variants of lipoprotein lipase (LPL), a key enzyme in the hydrolysis of triglyceride rich particles, may contribute to CAD. We analysed here the frequency of LPL variants (p.Asp9Asn, p.Asn291Ser and p.Ser447X) in a Tunisian population as well as their association with circulating lipid level and risk of CAD. PATIENTS AND METHODS: LPL variations were investigated by PCR-RFLP and lipid parameters were measured in 135 patients and 109 controls. RESULTS: The frequency of the p.Asp9Asn variation was 10.37% in CAD patients versus 3.66% in controls. The frequency for the p.Ser447X variation was 8.8% in CAD patients versus 13.7% in controls. There was no significant association between these two variants and CAD. The p.Asn291Ser mutation variation was absent in this population. In healthy subjects, heterozygote carriers of the p.Asp9Asn substitution had a significant increase level of total cholesterol (4.2±0.9mmol/L vs 5.6±1.2mmol/L; P=0.01) and a decreased level of HDL-cholesterol (1.36±0.3mmol/L vs 0.93±0.1mmol/L; P=0.045). CONCLUSION: There was no significant association between genetic variants of the LPL gene and CAD in this Tunisian population. The very low frequency of the p.Asn291Ser variation may be an ethnic specificity of Tunisians.

Effect of a splice site mutation in LDLR gene and two variations in PCSK9 gene in Tunisian families with familial hypercholesterolaemia.

Autosomal dominant hypercholesterolaemia (ADH) is due to defects in the LDL receptor gene (LDLR), in the apolipoprotein B-100 gene (APOB) or in the proprotein convertase subtilisin/kexin type 9 gene (PCSK9). The aim of this study was to identify and to characterize mutations at the origin of ADH in two Tunisian families. We found three genomic variations: (1) c.1845 + 1G > A, a splice site mutation in the LDLR gene and (2) two variations in the PCSK9 gene (p.Phe515Leu and p.Gly670Glu) that were both reported to be associated with high LDL-C levels. These results enlarge the spectrum of ADH-causative LDLR and PCSK9 variations in Tunisia. Our observations indicate that missense variations in the PCSK9 gene do not influence the clinical phenotype of ADH patients carrying a mutation in the LDLR gene.

+294T/C polymorphism in the PPAR-delta gene is associated with risk of coronary artery disease in normolipidemic Tunisians.

Peroxisome proliferator-activated receptor delta (PPAR-delta) is a transcription factor implicated in metabolism and inflammation. The +294T/C polymorphism in the PPAR-delta gene is associated with risk of coronary artery disease (CAD) in dyslipidemic women and hypercholesterolemic men. Whether this polymorphism influences the risk of CAD in the absence of dyslipidemia was not known, so we investigated a possible association of this polymorphism with plasma lipid and lipoprotein levels and with risk and outcome of CAD in a normolipidemic Tunisian population. Genotyping was performed by PCR-RFLP in 112 CAD patients and 113 healthy volunteers. The C-allele was significantly more frequent in patients than in controls (0.320 vs 0.189, P = 0.001). This association remained significant after adjustment for age, gender, body mass index, smoking, hypertension, and high-density lipoprotein cholesterol. Subjects carrying either one or two copies of the C-allele had a 2.7-fold higher risk of CAD than subjects homozygous for the T-allele. PPAR-delta genotypes were not associated with lipoprotein concentrations or outcome of CAD. We conclude that PPAR-delta +294T/C polymorphism is an independent risk factor of CAD in normolipidemic Tunisian subjects. The lack of association with lipoprotein concentrations suggests that the effect of the polymorphism on CAD is not mediated through lipoprotein levels in this population and that it may influence the atherosclerotic process through mechanisms involving inflammation.

[Extraparenchymental distribution and feasibility of selective clamping of segmental renal arteries during partial nephrectomy: a study of the dissection of 30 kidneys from recent nonformolised corpses]. / Distribution extraparenchymateuse et accessibilité au clampage sélectif des artères rénales segmentaires au cours de la néphrectomie partielle : à propos de la dissection de 30 reins de cadavres frais non formolés.

OBJECTIVE: To assess the feasibility of selective clamping of segmental renal arteries during partial nephrectomy, in order to limit renal infarction to the pathological area to be resected. MATERIALS AND METHODS: A dissection of renal artery and its extraparenchymal branches was realised. The study included 30 kidneys from recent nonformolised corpses. The size, distribution, and accessibility of the arteries were considered. All the corpses underwent a lombotomy with or without rib resection. RESULTS: The majority of dissected kidneys had a unique artery (96.66% of cases). The number of segmental arteries was zero in five cases (16.66%), one in four cases (13.33%), two in four cases (13.33%), three in one case (3%), four in 15 cases (50%) and five in five cases (16.66%). The posterior and inferior segmental arteries were more accessible to isolate with a respective ratio of 94 and 100% at segmental level. Apical and middle segmental arteries were least accessible with a respective ratio of 73 and 80%. The majority of accidents during dissection occurred with the middle segmental artery (62.5% of vascular lesions). CONCLUSION: This anatomic dissection on corpses showed that selective renal segmental arteries is possible in the majority of cases. This dissection is better indicated in partial nephrectomies for renal tumours located posteriorly or in the lower pole.