Effects of Cannabis Use on Neurocognition: A Scoping Review of MRI Studies.

Cannabis is one of the most commonly utilized recreational drugs. However, increasing evidence from the literature suggests harmful implications on cognition. Thus, the main aim of the current review is to summarize literature findings pertaining to the impact of cannabis on neurocognitive skills, focusing on the imaging biomarkers provided by MRI. Two reviewers navigated the literature independently using four main search engines including PubMed and Cochrane. Articles were first evaluated through their title and abstract, followed by full-text assessment. Study characteristics and findings were extracted, and the studies' quality was appraised. 47 articles were included. The majority of the studies were of a case-control design (66%), and the most studied neurocognitive skill was memory (40.4%). With task-based fMRI being the most commonly utilized MRI technique, findings have shown significantly varying decreased and increased neuronal activity within brain regions associated with the cognitive tasks performed. Results suggest that cannabis users are significantly suffering from cognitive deficits. The major significance of this review is attributed to highlighting the role of MRI. Future research needs to delve more into validating the negative effects of cannabis, to enable stakeholders to take action to limit cannabis usage, to foster public health and wellbeing.

Nanostructured Porous Silicon for Bone Tissue Engineering: Kinetics of Particle Degradation and Si-Controlled Release.

Nanostructured porous silicon (pSi) is a synthetic silicon-based material. Its biocompatibility and bioresorbability in body fluids make pSi an appealing biomaterial for tissue engineering, with surfaces characteristics facilitating human cell adhesion and differentiation. The resorption kinetics of such porous biomaterials is crucial for in vivo bone regeneration, in order to adapt biomaterial resorption to tissue formation, and to control the release of loaded bioactive molecules. We investigated pSi as a bioactive scaffold for bone tissue engineering, with an emphasis on kinetics of pSi resorption and silicon release. PSi particles and chips were fabricated from crystalline silicon, and functionalized by oxidation and chemical grafting of amine groups to mimic biological structures. Materials resorption over time was investigated with Raman spectroscopy, infrared spectroscopy, and Scanning Electron Microscopy. Silicon release was followed by mass spectrometry. Particle degradation and inclusion in newly formed bone were studied in vivo. The in vitro experiments revealed that non-oxidized pSi had an accelerated initial dissolution in ddH2O and an inhibition of initial Si release in SBF. This high reactivity also led to transformation towards amorphous non-resorbable silica when incubated in SBF. PSi resorption started immediately with a maximal dissolution in the first 24 h. Later, the dissolution rate decreased over time. In comparison, the resorption process of oxidized pSi seemed delayed, but more continuous. This delayed dissolution increased the bioactivity and stability, leading to enhanced bone formation in vivo. Delayed pSi degradation provided a constant surge of silicic acid over time and promoted bone regeneration, demonstrating the high potential of pSi for bone tissue engineering: Oxidized pSi were almost completely resorbed after 2 months of healing, with remaining partially dissolved particles surrounded by newly formed bone. On the contrary, non-oxidized particles were still obviously present after 2 months with limited bone regeneration. This delayed resorption is consistent with the in vitro observations in SBF, and particles' transformation towards silica.

Evaluation of the accuracy of new modalities in the assessment and classification of lumbar lordosis: A comparison to Cobb's angle measurement.

Background: Because of the association of lumbar lordosis with some clinical conditions such as low back pain, the chiropractic field has emphasized the significance of evaluating the lumbar lordotic status, by measuring Cobb's angle, regarded as the radiological gold standard, for the assessment of lumbar lordosis, on lateral radiographs. However, research has shown that this technique has some considerable drawbacks, mostly in terms of low accuracy and high variability between clinicians when compared with other radiological modalities. The main objective was to compare the diagnostic accuracy of newly established radiological measurements with one of Cobb's angle methods, for the characterization of lumbar lordosis status in a sample of Lebanese patients aged 15 and above. Material and methods: This retrospective single-center study consisted of measuring Cobb's L1-S1 and Cobb's L1-L5 angles, along with the novel established measurements which are the derivative and the normalized surface area, on 134 lateral radiographs of the lumbar spine of Lebanese patients aged fifteen years old and above, gotten from the Radiology department at Zahra'a's Hospital in Beirut, performed by two observers using MATLAB. Inter-rater agreement was assessed by calculating the Intra-class correlation coefficients. Spearman correlation was analyzed between both Cobb's angle methods and with the derivative and normalized area respectively. 54 patients of the sample were diagnosed by two radiologists, according to their LL status. ROC curve analysis was performed to compare the diagnostic accuracy of the four techniques used. Data were analyzed with IBM SPSS Statistics 23.0 (NY, USA); P < 0.05 was considered statistically significant. Results: According to the ROC curve analysis the new methods, which are the derivative and the normalized surface area, displayed lower diagnostic accuracy (AUCderivative = 0.818 and 0.677, AUCsurface area = 0.796 and 0.828) than Cobb's L1-L5 (AUCL1-L5 = 0.924 and 0.929 values) and L1-S1 (AUCL1-S1 = 0.971 and 0.955) angles, in the characterization of hypo and hyperlordotic patients, respectively, in our Lebanese sample consisting of patients aged 15 and above, because of their lower area under the curve's values compared to the traditional Cobb's techniques. The Cobb's L1-S1 has shown to have the highest diagnostic accuracy among the four methods to characterize normal patients from hypo and hyperlordotic ones, by referring to its highest area under the curve's values. However, the sensitivity of Cobb's L1-L5 angle in characterizing hyperlordotic patients was similar to the one of the normalized surface area with a value of 100%.Conclusion: among the four modalities, the new methods didn't show a better diagnostic accuracy compared to the traditional modalities. Cobb's L1-S1 displayed the highest diagnostic accuracy despite its drawbacks. Further prospective studies are needed to validate the cut-offs obtained for Cobb's L1-S1 angle in our sample.

Association between vitamin D deficiency and multiple sclerosis- MRI significance: A scoping review.

Background/Objective: Multiple Sclerosis is a common demyelinating disease of the central nervous system. Several studies suggested a link between vitamin D deficiency and multiple sclerosis disease activity, which can be evaluated by magnetic resonance imaging. Thereby, the main objective of the following scoping review is to summarize the magnetic resonance imaging findings assessing the probable effects of vitamin D on MS disease activity. Methodology: PRISMA checklist for systematic reviews and meta-analyses was employed to structure this review. Literature was searched for observational and clinical studies tackling the given matter using several search engines including PubMed, CORE, and Embase. Data was extracted in a systematic manner, and the articles meeting the inclusion criteria were quality-assessed by Jadad scale for randomized clinical trials (RCTs) and Newcastle-Ottawa scale for observational studies. Results: A total of 35 articles were included. Twenty-one (60%) studies noted a statistically significant association between vitamin D and Multiple Sclerosis MRI-detected disease activity. MRI-detected features involved lower contrast-enhancing T1 lesions, lower hyperintense T2 lesions, and a decrease in lesions volume. On the other hand, 40% (14 articles) of the articles did not detect any significant effect of vitamin D on Multiple Sclerosis disease activity. Due to the heterogeneity of the studies involved, meta-analysis was not employed in the given review. Discussion/conclusion: There was an abundance in the number of research studies investigating the relationship between vitamin D and Multiple Sclerosis while highlighting the significant role of MRI in assessing the activity of the disease. Numerous studies found that higher serum vitamin D levels are associated with decreased new active cortical and subcortical lesions and lower lesions volume. These findings highlight the importance of imaging modalities in the various aspects of neurological diseases and encourage further research to focus on the preventive effects of vitamin D on MS patients.

Properties of dentin, enamel and their junction, studied with Brillouin scattering and compared to Raman microscopy.

OBJECTIVE: Dentin, enamel and the transition zone, called the dentin-enamel junction (DEJ), have an organization and properties that play a critical role in tooth resilience and in stopping the propagation of cracks. Understanding their chemical and micro-biomechanical properties is then of foremost importance. The aim of this study is to apply Brillouin microscopy on a complex biological structure, that is, the DEJ, and to compare these results with those obtained with Raman microscopy. DESIGN: Both techniques allow noncontact measurements at the microscopic scale. Brillouin microscopy is based on the interaction between acoustic phonons and laser photons and gives a relation between the frequency shift of the scattered light and the stiffness of the sample. Raman spectra contain peaks related to specific chemical bonds. RESULTS: Comparison of the Brillouin and Raman cartographies reveals correlations between mechanical and chemical properties. Indeed, the shapes of the phosphate content and stiffness curves are similar. The two spectroscopies give compatible values for the mean distance between two tubules, i.e., 4-6 µm. Moreover, for the first time, the daily cross striations of enamel could be studied, indicating a relationship between the variation in the phosphate concentration and the variation in the rigidity within the enamel prisms. CONCLUSIONS: We demonstrate here the possibility of using Brillouin scattering microscopy to both study complex biological materials such as the enamel-dentin junction and visualize secondary structures. Correlations between the chemical composition and mechanical properties could help in better understanding the tissue histology.

Enamel and dentin in Enamel renal syndrome: A confocal Raman microscopy view.

Enamel Renal Syndrome (ERS) is a rare genetic disorder caused by biallelic mutations in Family with sequence similarity 20A (FAM20A) gene encoding the secretory pathway pseudokinase FAM20A. ERS is characterized by hypoplastic amelogenesis imperfecta (AI), impaired tooth eruption, intra-pulpal calcifications, gingival fibromatosis and nephrocalcinosis of various severity. Previous studies showed that the hypoplastic enamel was also hypomineralized but its chemical composition has not been extensively studied. Furthermore it is currently unclear whether dentinal defects are associated with AI in ERS patients. The objective of the study was to provide a structural and chemical analysis of enamel, dentin and dentin enamel junction (DEJ) in ERS patients carrying four, previously reported, distinct mutations in FAM20A. Chemical cartography obtained with Raman microscopy showed that compared to control samples, ERS enamel composition was severely altered and a cementum-like structure was observed in some cases. Chemical composition of peripulpal dentin was also affected and usual gradient of phosphate intensity, shown in DEJ profile, was absent in ERS samples. DEJ and dentinal anomalies were further confirmed by scanning electron microscopy analysis. In conclusion, our study shows that enamel formation is severely compromised in ERS patients and provides evidence that dentinal defects are an additional feature of the ERS dental phenotype.

Fabrication of Radio-Opaque and Macroporous Injectable Calcium Phosphate Cement.

The aim of this work was the development of injectable radio-opaque and macroporous calcium phosphate cement (CPC) to be used as a bone substitute for the treatment of pathologic vertebral fractures. A CPC was first rendered radio-opaque by the incorporation of zirconium dioxide (ZrO2). In order to create macroporosity, poly lactic-co-glycolic acid (PLGA) microspheres around 100 µm were homogeneously incorporated into the CPC as observed by scanning electron microscopy. Physicochemical analyses by X-ray diffraction and Fourier transform infrared spectroscopy confirmed the brushite phase of the cement. The mechanical properties of the CPC/PLGA cement containing 30% PLGA (wt/wt) were characterized by a compressive strength of 2 MPa and a Young's modulus of 1 GPa. The CPC/PLGA exhibited initial and final setting times of 7 and 12 min, respectively. Although the incorporation of PLGA microspheres increased the force necessary to inject the cement and decreased the percentage of injected mass as a function of time, the CPC/PLGA appeared fully injectable at 4 min. Moreover, in comparison with CPC, CPC/PLGA showed a full degradation in 6 weeks (with 100% mass loss), and this was associated with an acidification of the medium containing the CPC/PLGA sample (pH of 3.5 after 6 weeks). A cell viability test validated CPC/PLGA biocompatibility, and in vivo analyses using a bone defect assay in the caudal vertebrae of Wistar rats showed the good opacity of the CPC through the tail and a significant increased degradation of the CPC/PLGA cement a month after implantation. In conclusion, this injectable CPC scaffold appears to be an interesting material for bone substitution.

[Some scientific highlights from early 2022: A selection by the students of the Master Biology-Health of Montpellier University]. / L'actualité scientifique de ce début 2022 vue par les étudiants du Master Biologie Santé de l'université de Montpellier.

TITLE: L'actualité scientifique de ce début 2022 vue par les étudiants du Master Biologie Santé de l'université de Montpellier. ABSTRACT: L'unité d'enseignement « Immunopathologie ¼ qui propose les brèves présentées dans ce numéro est suivie par des étudiants de divers parcours du Master Biologie Santé de l'Université de Montpellier. Ce Master rassemble des étudiants issus du domaine des sciences et technologies et de celui de la santé. On y étudie les bases physiopathologiques des maladies immunologiques, les cibles thérapeutiques et les mécanismes d'échappement des microorganismes et des tumeurs. Les articles présentés ont été choisis par les étudiants selon leur domaine de prédilection.

Confocal Raman data analysis of tufts and spindles at the human dentin-enamel junction.

OBJECTIVE: The aim of this article is to analyze the chemical mapping of tufts and spindles of the human dental enamel using confocal Raman microscopy measuring length, structuration and composition of spindles and tufts. DESIGN: we used Raman diffusion, based on the interaction between photons and optic phonons, to reveal chemical bound. Adult molars were selected and longitudinally sectioned. Areas of 120 * 120 µm were scanned near the dentin-enamel junction and grooves. Spectra were collected and phosphate and proteins peak intensities images were reconstructed, related to HPA concentration. Images of Phosphate (PO43-, 960 cm-1) and protein (CH, 2800/3000 cm-1) intensities have been reconstructed. K-mean cluster has been calculated to compare centroid spectra from enamel, dentin and tuft or spindle. RESULTS: intensity profile revealed spindles as less mineralized areas than enamel, from 5 to 10 µm large. In the groove of molar, long tufts were found, more than 150 µm. CONCLUSIONS: Confocal Raman microscopy is a very interesting tool to characterize chemically secondary structure of enamel. The size of a tuft in the groove allows us make the hypothesis that they could play a role in long term resilience of mechanical stress.

Effectiveness of anchorage with temporary anchorage devices during anterior maxillary tooth retraction: A randomized clinical trial.

OBJECTIVE: This study evaluated the efficiency of anchorage provided by temporary anchorage devices (TADs) in maxillary bicuspid extraction cases during retraction of the anterior teeth using a fixed appliance. METHODS: Patients aged 12 to 50 years with malocclusion for which bilateral first or second maxillary bicuspid extractions were indicated were included in the study and randomly allocated to the TAD or control groups. Retraction of the anterior teeth was achieved using skeletal anchorage in the TAD group and conventional dental anchorage in the control group. A computed tomography (CT) scan was performed after alignment of teeth, and a second CT scan was performed at the end of extraction space closure in both groups. A three-dimensional superimposition was performed to visualize and quantify the maxillary first molar movement during the retraction phase, which was the primary outcome, and the stability of TAD movement, which served as the secondary outcome. RESULTS: Thirty-four patients (17 in each group) underwent the final analysis. The two groups showed a significant difference in the movement of the first maxillary molars, with less significant anchorage loss in the TAD group than that in the control group. In addition, TAD movement showed only a slight mesial movement on the labial side. On the palatal side, the mesial TAD movement was greater. CONCLUSIONS: In comparison with conventional dental anchorage, TADs can be considered an efficient source of anchorage during retraction of maxillary anterior teeth. TADs remain stable when correctly placed in the bone during the anterior tooth retraction phase.

Formation and assessment of enamel subsurface lesions in vitro.

The present study compared two pH-cycling models designed to induce subsurface lesions (SLs) with a less demineralized surface layer on teeth, with the aim of developing new technologies for assessment of such lesions by examining the performance of confocal Raman microscopy for detection of white spot lesions (WSLs). Twelve sound premolars were exposed to two sets of model conditions (A, B) designed to induce SLs. Teeth on which white lesions had formed in vivo were used as positive controls. All specimens were inspected using an intraoral camera and Raman microscopy to detect small changes in the appearance and structure of the enamel. Changes in the natural color of the teeth during the treatment were recorded via the camera. Phosphate maps with their spectra were constructed from the phosphate peak at 960 cm-1. The depth of lesions was measured on the basis of variations in phosphate peak intensity. Protocol B was reliable for reproducing SLs in a relatively short period. Both protocols had intrinsic limitations in not completely simulating the complex intraoral conditions leading to WSL formation with respect to lesion depth and preservation of an intact surface layer. Raman microscopy can be considered the gold standard for analysis of hard tissue mineralization.

Confocal Raman mapping of collagen cross-link and crystallinity of human dentin-enamel junction.

The separation zone between enamel and dentin [dentin-enamel junction (DEJ)] with different properties in biomechanical composition has an important role in preventing crack propagation from enamel to dentin. The understanding of the chemical structure (inorganic and organic components), physical properties, and chemical composition of the human DEJ could benefit biomimetic materials in dentistry. Spatial distribution of calcium phosphate crystallinity and the collagen crosslinks near DEJ were studied using confocal Raman microscopy and calculated by different methods. To obtain collagen crosslinking, the ratio of two peaks 1660 cm-1 over 1690 cm-1 (amide I bands) is calculated. For crystallinity, the inverse full-width at half maximum of phosphate peak at 960 cm-1, and the ratio of two Raman peaks of phosphate at 960/950 cm-1 is provided. In conclusion, the study of chemical and physical properties of DEJ provides many benefits in the biomaterial field to improve the synthesis of dental materials in respect to the natural properties of human teeth. Confocal Raman microscopy as a powerful tool provides the molecular structure to identify the changes along DEJ and can be expanded for other mineralized tissues.

Method to evaluate the noise of 3D intra-oral scanner.

In dentistry, 3D intra-oral scanners are gaining increasing popularity essentially for the production of dental prostheses. However, there is no normalized procedure to evaluate their basic performance and enable comparisons among intra-oral scanners. The noise value highlights the trueness of a 3D intra-oral scanner and its capacity to plan prosthesis with efficient clinical precision. The aim of the present study is to develop a reproducible methodology for determining the noise of an intra-oral scanner. To this aim, and as a reference, an ultra-flat and ultra-smooth alumina wafer is used as a blank test. The roughness is calculated using an AFM (atomic force microscope) and interferometric microscope measurements to validate this ultra-flat characteristic. Then, two intra-oral scanners (Carestream CS3500 and Trios 3Shape) are used. The wafer is imaged by the two intra-oral scanners with three different angles and two different directions, 10 times for each parameter, given a total of 50 3D-meshes per intra-oral scanner. RMS (root mean square), representing the noise, is evaluated and compared for each angle/direction and each intra-oral scanner, for the whole mesh, and then in a central ROI (region of interest). In this study, we obtained RMS values ranging between 5.29 and 12.58 micrometers. No statistically significant differences were found between the mean RMS of the two intra-oral scanners, but significant differences in angulation and orientations were found between different 3D intra-oral scanners. This study shows that the evaluation of RMS can be an indicator of the value of the noise, which can be easily assessed by applying the present methodology.

A New Rat Model for Translational Research in Bone Regeneration.

The European Union (EU) directive 2010/63/EU on the protection of animals used for scientific purpose focused on reducing the number of animals and refinement of breeding. Animal studies are necessary to protect human health. Lots of animal models exist to study bone regeneration, but a reliable, well reproducible, and relatively inexpensive model with the possibility for multiple testing in the same animal is still missing. Rats may serve as good models for this due to the small animal size and good cost/benefit ratio. The present study aimed to develop a novel rat caudal vertebrae critical size defect model for bone regeneration and implant osseointegration studies The study was performed using Wistar rats with weight from 380 to 450 g. An incision was made on the dorsal side of the tail. After skin and muscles retractions, the vertebrae were exposed. Critical size defects for bone tissue engineering or implant placements for titanium body experiments were possible in each of the first four caudal vertebrae. Micro-computed tomography (CT) and histology were used to detect bone growth. There was no bone formation in the defects after 1 or 2 months of healing. When a calcium phosphate biomaterial was used (Bio-Oss®; Geistlich Pharma AG, Wolhusen, Switzerland), a good stability of the material in the defect was noted and bone growth was visible after 1 or 2 months. Results based on implant placement showed good primary stability after 3 months of healing. MicroCT showed integrated implant position through the vertebra. These results suggest that the rat caudal vertebrae may serve as a good new model for studying bone regeneration and implant osseointegration with the possibility of multiple testing within the same experimental animal and the potential to decrease number of experimental animals.