We perform local or microrheological measurements on microtubule solutions, as well as composite networks. The viscoelastic properties of microtubules as reported from two-point microrheology agree with the macroscopic measurement at high frequencies, but appear to show a discrepancy at low frequencies, at time scales on the order of a second. A composite of filamentous actin (F-actin) and microtubules has viscoelastic behavior between that of F-actin and pure microtubules. We further show that the Poisson ratio of the composite, measured by the length-scale dependent two-point microrheology, is robustly smaller than that of the F-actin network at time scales tau>1 s, suggesting that a local compressibility is conferred by the addition of microtubules to the F-actin network.

We evaluated the transport of polymeric particles internalized into living cancer cells. The mean-square displacement demonstrates superdiffusion with a scaling exponent of 1.25. Scaling exponents of a range of displacement moments are bilinear with moment order, exhibiting slopes of 0.6 and 0.8. Thus, we present experimental evidence of strong anomalous diffusion. Bilinearity indicates that particle motion is composed of subdiffusive regimes separated by active yet nonballistic flights. We discuss the results in terms of particle interactions with their microenvironment.

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Mechanics of cancer cells are directly linked to their metastatic potential, or ability to produce a secondary tumor at a distant site. Metastatic cells survive in the circulatory system in a non-adherent state, and can squeeze through barriers in the body. Such considerable structural changes in cells rely on rapid remodeling of internal structure and mechanics. While external mechanical measurements have demonstrated enhanced pliability of cancer cells with increased metastatic potential, little is known about dynamics of their interior and we expect that to change significantly in metastatic cells. We perform a comparative study, using particle-tracking to evaluate the intracellular mechanics of living epithelial breast cells with varying invasiveness. Particles in all examined cell lines exhibit super-diffusion with a scaling exponent of 1.4 at short lag times, likely related to active transport by fluctuating microtubules and their associated molecular motors. Specifics of probe-particle transport differ between the cell types, depending on the cytoskeleton network-structure and interactions with it. Our study shows that the internal microenvironment of the highly metastatic cells evaluated here is more pliable and their cytoskeleton is less dense than the poorly metastatic and benign cells. We thus reveal intracellular structure and mechanics that can support the unique function and invasive capabilities of highly metastatic cells.

Objectives: To assess and compare diet practices, body mass index (BMI), and oral health-related quality of life (OHRQoL) in adults with and without periodontitis. Methods: Demographics, health-related behaviors, BMI, dental and periodontal parameters, diet practices, and Oral Health Impact Profile-14 (OHIP-14) were collected from 62 periodontitis patients and 100 controls without periodontitis. Results: Having periodontitis was positively associated with male sex (p = 0.004), older age (p < 0.001), smoking pack-years (p = 0.006), weight (p = 0.008), BMI (p = 0.003), number of meals per day (p < 0.001) and had a negative association with decayed teeth (p = 0.013), alcohol (p = 0.006), and sweets (p = 0.007) consumption. Periodontitis patients were more likely to avoid carbonated beverages (p = 0.028), hot (p = 0.003), and cold drinks (p = 0.013), cold (p = 0.028), hard textured (p = 0.002), and fibrous foods (p = 0.02) than the controls, and exhibited higher global OHIP-14 (p < 0.001) and most domain scores. Age (p < 0.001), BMI (p =0.045), number of meals per day (p = 0.024), and global OHIP-14 score (p < 0.001) remained positively associated with periodontitis in the multivariate analysis. Conclusions: Periodontitis patients exhibited higher BMI and altered diet practices and OHRQoL as compared to controls. Assessment of diet practices, BMI, and OHRQoL should be part of periodontal work-up. Dentists and dietitians should collaborate to design strategies to address these challenges.