3D segmentation of joint space using low dose imaging for early diagnosis of knee osteoarthritis

L'arthrose est une maladie dégénérative de l'articulation qui provoque des douleurs, une raideur et une diminution de mobilité. La quantification de l’interligne articulaire est la mesure qui permet de diagnostiquer la maladie et de suivre son évolution. A ce jour, la radiographie conventionnelle est la méthode de référence pour ce diagnostic et ce suivi. Néanmoins, l'articulation du genou et ses modifications structurales sont trop complexes pour permettre un diagnostic à un stade précoce à partir de simples images 2D. Une des pistes prometteuses de la recherche sur le diagnostic précoce est l’exploitation de l’information 3D de l’interligne. C’est dans ce contexte que s’inscrit cette thèse qui a pour but la segmentation et la quantification 3D de l’interligne articulaire afin d’atteindre l’objectif du diagnostic précoce de l’arthrose de genou. Au cours de cette thèse nous avons développé une méthode de quantification semi-automatique de l’interligne articulaire. La cartographie 3D des distances générée a permis de caractériser la morphologie de l’espace articulaire sur des images haute résolution 3D. Pour atteindre l’objectif de quantification à basse dose, deux approches ont été explorées. La première consistait à proposer une approche de segmentation 3D du volume osseux à partir d’un faible nombre de projections. La deuxième approche consiste à réaliser la quantification 3D de l’interligne sur des images issus d’un scanner basse dose obtenue à l’aide d’autres algorithmes mis en œuvre par les partenaires du projet VOXELO. La segmentation de l’interligne a été dans ce cas utilisée comme un critère de qualité de la reconstruction selon ces différents algorithmes.Afin de tester la robustesse de notre approche, nous avons utilisé des images haute résolution selon 2 types de géométrie du faisceau ou des images à faible dose et également sur des images scanner clinique in vivo. Ceci nous permet de conclure que la méthode de quantification de l’interligne que nous avons développé en 3D est potentiellement applicable sur des images provenant de différents appareils de scanner. Cet outil sera potentiellement utile pour détecter les stades précoces et suivre la progression de l'arthrose en clinique.Osteoarthritis (OA) is a degenerative joint disease that causes pain, stiffness and decrease mobility. Knee OA presents the greatest morbidity. The main characteristic of OA is the cartilage loss inducing joint space narrowing. Usually, the diagnosis and progression of OA is monitored by the joint space measurement. Actually, conventional radiography is the reference method for the diagnosis and monitoring. However, the knee joint and structural changes are too complex to be assessed from simple 2D images especially at early stage. A promising research into early diagnosis is the use of 3D. The objective of our thesis is to provide a tool for a 3D quantification of joint space in order to achieve the goal of early diagnosis of knee osteoarthritis. In this thesis we have developed a semi-automatic method for the quantification of joint space. The 3D map generated allowed us to characterize the morphology of the joint space widths on 3D high resolution images.To achieve the goal of low-dose quantification, two approaches have been explored. The first was to provide a 3D segmentation method for bone extraction from a limited number of projections. The second approach is to perform the 3D quantification from a low dose scan obtained using other algorithms implemented by our partners of VOXELO project. The segmentation of the joint space was used as a quality criterion according to these different algorithms.To test the robustness of our approach, we used high-resolution images with different geometry acquisition types and low-dose images. We have also done a test on clinical CT images in vivo. This allows us to conclude that the method we developed is potentially applicable to images from different scanner devices. This tool can be used for detecting the early stages and track the progress of the clinical osteoarthriti

Antioxidant and antibacterial activities, interfacial and emulsifying properties of the apo and holo forms of purified camel and bovine α-lactalbumin

International audienceThe antioxidant and antibacterial activities of camel and bovine α-lactalbumin (α-La) in both calcium-loaded (holo) and calcium-depleted (apo) forms were investigated and compared. Antioxidant assay showed that camel and bovine α-La exhibited significant Ferric-reducing antioxidant power (FRAP), ferrous iron-chelating activity (FCA) and antiradical activities especially in their apo form. Camel apo α-La also exhibited attractive antibacterial activities against Gram-negative bacteria (Pseudomonas aeruginosa) and against fungal pathogens species (Penicillium bilaiae, Aspergillus tamari and Aspergillus sclerotiorum). Likewise, emulsifying properties (emulsification ability (EAI) and stability (ESI) indexes) and the surface characteristics (surface hydrophobicity, ζ-potential and interfacial tension) of the α-La were assessed. Maximum EAI were found at pH 7.0, with higher EAI values for the camel apo α-La (EAI ~19.5 m2/g). This behavior was explained by its relative high surface hydrophobicity and its greater efficiency to reduce the surface tension at the oil-water interface. Furthermore, emulsions were found to be more stable at pH 7.0 compared to pH 5.0 (ESI ~50%) due to the higher electrostatic repulsive forces between oil droplets at pH 7.0 in consistence with the ζ-potential results. This study concluded that the camel apo α-La has antibacterial, antioxidant, and emulsifying properties in agricultural and food industries

Isolation and structural characterization of levan produced by probiotic Bacillus tequilensis-GM from Tunisian fermented goat milk

The probiotic features of strain GM newly isolated from Tunisian spontaneously fermented goat milk and identified as Bacillus tequilensis-GM were assessed. Strain GM showed high resistance to saliva (90.64%), gastric juice (88.55%), intestinal juice (72.83%) and resistance to bile salts (65.22%), was able to act against Listeria monocytogenes ATCC 15313, Escherichia coli ATCC 25922 and Enterococcus feacalis ATCC 25912, showed high surface hydrophobicity (77.3%) and was sensitive to most of the studied antibiotics. Strain GM did not exhibit any hemolytic activity whereas it was able to produce protease, amylase and β-galactosidase. Moreover, results showed that strain GM produced high molecular weight β-(2 → 6)-levan with high ability to inhibit and to disrupt pathogenic biofilms and with high ability to reduce syneresis of sucrose-supplemented skimmed milk. B. tequilensis-GMcan therefore be suitable to be used as starter culture in fermented dairy products, since it possesses desirable probiotic properties in addition to its ability to produce levan

Production and structural characterization of exopolysaccharides from newly isolated probiotic lactic acid bacteria

In this work, four exopolysaccharide-producing lactic acid bacteria (LAB) strains, newly isolated fromTunisian spontaneously fermented foods and beverages, namely bovine and turkey meat sausages(BMS and TMS), date palm sap (DPS) and cow milk (CM), were identified as Leuconostoc citreum-BMS,Leuconostoc mesenteroides-TMS, Pediococcus pentosaceus-DPS and Leuconostoc pseudomesenteroides-CM,respectively. The isolated strains showed the ability to withstand simulated human gastrointestinal (GI)tract conditions (low pH, lysozyme, bile salts, pepsin and pancreatin) and showed high surface hydropho-bicity (79–90%), besides their ability to act against Escherichia coli and Listeria monocytogenes and toproduce exopolysaccharides (EPS). Therefore, these isolates can be served as potential probiotics. The pro-duced EPS were growth-associated suggesting that they are primary metabolites. The molecular weightswere higher than 106Da using HPLC-SEC. 2D-NMR results indicated that all the samples were mixtures ofdextran and levan, except for EPS-CM which was a levan-type EPS. Furthermore, the EPS samples showedan abitlity to inhibit and to disrupt pathogenic biofilms and showed high thermostability studied via dif-ferential scanning calorimetry (DSC) with melting points higher than 224◦C making them promising tobe used in thermal processed foods

Production and structural characterization of exopolysaccharides from newly isolated probiotic lactic acid bacteria

In this work, four exopolysaccharide-producing lactic acid bacteria (LAB) strains, newly isolated fromTunisian spontaneously fermented foods and beverages, namely bovine and turkey meat sausages(BMS and TMS), date palm sap (DPS) and cow milk (CM), were identified as Leuconostoc citreum-BMS,Leuconostoc mesenteroides-TMS, Pediococcus pentosaceus-DPS and Leuconostoc pseudomesenteroides-CM,respectively. The isolated strains showed the ability to withstand simulated human gastrointestinal (GI)tract conditions (low pH, lysozyme, bile salts, pepsin and pancreatin) and showed high surface hydropho-bicity (79–90%), besides their ability to act against Escherichia coli and Listeria monocytogenes and toproduce exopolysaccharides (EPS). Therefore, these isolates can be served as potential probiotics. The pro-duced EPS were growth-associated suggesting that they are primary metabolites. The molecular weightswere higher than 106Da using HPLC-SEC. 2D-NMR results indicated that all the samples were mixtures ofdextran and levan, except for EPS-CM which was a levan-type EPS. Furthermore, the EPS samples showedan abitlity to inhibit and to disrupt pathogenic biofilms and showed high thermostability studied via dif-ferential scanning calorimetry (DSC) with melting points higher than 224◦C making them promising tobe used in thermal processed foods

Providencia entomophila sp. nov., a new bacterial species associated with major olive pests in Tunisia.

Bioprospection for potential microbial biocontrol agents associated with three major insect pests of economic relevance for olive cultivation in the Mediterranean area, namely the olive fly, Bactrocera oleae, the olive moth, Prays oleae, and the olive psyllid, Euphyllura olivina, led to the isolation of several strains of readily cultivable Gram-negative, rod-shaped bacteria from Tunisian olive orchards. Determination of 16S ribosomal RNA encoding sequences identified the bacteria as members of the taxonomic genus Providencia (Enterobacterales; Morganellaceae). A more detailed molecular taxonomic analysis based on a previously established set of protein-encoding marker genes together with DNA-DNA hybridization and metabolic profiling studies led to the conclusion that the new isolates should be organized in a new species within this genus. With reference to their original insect association, the designation "Providencia entomophila" is proposed here for this hypothetical new taxon

Exploring Bacterial and Fungal Biodiversity in Eight Mediterranean Olive Orchards (Olea europaea L.) in Tunisia

A wide array of bacteria and fungi are known for their association with pests that impact the health of the olive tree. The latter presents the most economically important cultivation in Tunisia. The microbial diversity associated with olive orchards in Tunisia remains unknown and undetermined. This study investigated microbial diversity to elucidate the microbial interactions that lead to olive disease, and the bio-prospects for potential microbial biocontrol agents associated with insect pests of economic relevance for olive cultivation in the Mediterranean area. Bacterial and fungal isolation was made from soil and olive tree pests. A total of 215 bacterial and fungal strains were randomly isolated from eight different biotopes situated in Sfax (Tunisia), with different management practices. 16S rRNA and ITS gene sequencing were used to identify the microbial community. The majority of the isolated bacteria, Staphylococcus, Bacillus, Alcaligenes, and Providencia, are typical of the olive ecosystem and the most common fungi are Penicillium, Aspergillus, and Cladosporium. The different olive orchards depicted distinct communities, and exhibited dissimilar amounts of bacteria and fungi with distinct ecological functions that could be considered as promising resources in biological control