Environmentally dependent and independent control of cell shape determination by Rho GTPase regulators in melanoma

In order to invade 3D tissues, cancer cells dynamically change cell morphology in response to geometric and mechanical cues in the environment. But how cells determine their shape in 3D versus 2D environments is poorly understood. Studying 2D versus 3D single cell shape determination has historically been technically difficult due to the lack of methodologies to directly compare the two environments. We developed an approach to study cell shape in 2D versus 3D by measuring cell shape at different depths in collagen using stage-scanning oblique plane microscopy (ssOPM). We find characteristic shape changes occur in melanoma cells depending on whether a cell is attached to a 2D surface or 3D environment, and that these changes can be modulated by Rho GTPase regulatory proteins. Our data suggest that regulation of cell protrusivity undergoes a switch of control between different Rho GTPase regulators depending on the physical microenvironment.

MORPHOLOGICAL ASPECTS OF THE RELATIONSHIP BETWEEN PERIODONTAL TISSUES AND DENTAL PULP

Researchers are currently paying more and more attention to the combined pathology of the tooth pulp and periodontal. At the same time, the peculiarities of the structure of the alveolar bone, the cement of the tooth root and the root canal system that cause their interrelation and mutual influence remain insufficiently studied. The main elements of the connection between the pulp and periodontal tissues are not only apical openings and additional channels, but also other ways of interaction, the study of which is of great interest for understanding the features of pathogenesis, prognosis and treatment of combined diseases of the tooth pulp and periodontal. The aim of the study is to identify the topographical and anatomical features of the structure of the roots of teeth of different functional groups and the surfaces of their holes when studying on human cadaver material. The hypothesis of the study is that the number of openings of the Haversov channels and their localization in the moons are due to the functional affiliation of the teeth and they have their own characteristics. Material and methods. The study was conducted on jawbones with teeth obtained from embalmed corpses of adults of different genders and ages. After appropriate preparation, at the first stage, microscopy of the alveolar surfaces was performed, followed by morphometric analysis of the photos. At the second stage, scanning electron microscopy (SEM) of the surfaces of the roots of teeth previously extracted from the same wells of the jaws was performed. Results and discussion. All the preparations were systematized according to the number and topography of the identified holes of the Haversov channels. Because of the assessment of morphometric indicators, the number of holes, the density of their location and the diameter were determined, depending on the functional affiliation of the teeth. The analysis of microphotographs obtained because of SEM allowed us to determine the structural features of the surfaces of the roots of the teeth. Conclusions. The number, density and diameter of the holes of the Haversov channels are determined by the functional affiliation of the tooth. With the help of SEM, micro cracks and areas of root dentin exposure were found on the surfaces of the roots of the teeth for the first time, which can contribute to the translocation of pathogenic microbiota from the periodontal pocket to the pulp of the tooth and vice versa.

Rapid High-Resolution Mosaic Acquisition for Photoacoustic Remote Sensing

Mechanical stages are routinely used to scan large expanses of biological specimens in photoacoustic imaging. This is primarily due to the limited field of view (FOV) provided by optical scanning. However, stage scanning becomes impractical at higher scanning speeds, or potentially unfeasible with heavier samples. Also, the slow scan-rate of the stages makes high resolution scanning a time-consuming process. Some clinical applications such as microsurgery require submicron resolution in a reflection-mode configuration necessitating a method that can acquire large field of views with a small raster scanning step size. In this study, we describe a method that combines mechanical stages with optical scanning for the rapid acquisition of high-resolution large FOVs. Optical scanning is used to acquire small frames in a two-dimensional grid formed by the mechanical stages. These frames are captured with specific overlap for effective image registration. Using a step size of 200 nm, we demonstrate mosaics of carbon fiber networks with FOVs of 0.8 × 0.8 mm2 captured in under 70 s with 1.2 µm image resolution. Larger mosaics yielding an imaging area of 3 × 3 mm2 are also shown. The method is validated by imaging a 1 × 1 mm2 section of unstained histopathological human tissue.

Combined Effects of Chopped Carbon and Glass Fibres on Mechanical Properties of Lime-Based Mortar

Lime-based mortars have been used as bonding materials between stones or bricks since ancient times. It is an integral part of many structures and generally is used to fill the gaps between construction blocks (mortar joint) and strengthen the structures. Nowadays, different organic and inorganic substances are added to mortars in order to improve their physical and mechanical properties. This study deals with the combined effects of chopped carbon and glass fibres on mechanical properties of hydraulic lime-based mortar. Accordingly, lime-based mortar is prepared and chopped carbon (CCF) and glass (CGF) fibres are used as reinforcing materials in the lime-based mortar (1% by plain mortar weight). Five different combinations are investigated: Mixture-1 (100% CCF + 0% CGF), Mixture-2 (75% CCF + 25% CGF), Mixture-3 (50% CCF + 50% CGF), Mixture-4 (25% CCF + 75% CGF), Mixture-5 (0% CCF + 100% CGF). After reinforcing process, mechanical characterization tests are conducted on the mixtures at the end of 28 days curing. In the second stage, scanning electron microscope (SEM) observations and high definition visual inspection are carried out in order to investigate the interface mechanism between fibres and mortar. In the third stage, one-way analysis of variance (ANOVA) is performed to see whether differences between mechanical properties are statistically significant.