Poroelasticity of cartilage at the nanoscale

Atomic-force-microscopy-based oscillatory loading was used in conjunction with finite element modeling to quantify and predict the frequency-dependent mechanical properties of the superficial zone of young bovine articular cartilage at deformation amplitudes, δ, of ∼15 nm; i.e., at macromolecular length scales. Using a spherical probe tip (R ∼ 12.5 μm), the magnitude of the dynamic complex indentation modulus, |E^∗|, and phase angle, φ, between the force and tip displacement sinusoids, were measured in the frequency range f ∼ 0.2–130 Hz at an offset indentation depth of δ₀ ∼ 3 μm. The experimentally measured |E^∗| and φ corresponded well with that predicted by a fibril-reinforced poroelastic model over a three-decade frequency range. The peak frequency of phase angle, f_peak, was observed to scale linearly with the inverse square of the contact distance between probe tip and cartilage, 1/d², as predicted by linear poroelasticity theory. The dynamic mechanical properties were observed to be independent of the deformation amplitude in the range δ = 7–50 nm. Hence, these results suggest that poroelasticity was the dominant mechanism underlying the frequency-dependent mechanical behavior observed at these nanoscale deformations. These findings enable ongoing investigations of the nanoscale progression of matrix pathology in tissue-level disease.     

In Vitro Infectivity Assessment by Drug Susceptibility Comparison of Recombinant Leishmania major Expressing Enhanced Green Fluorescent Protein or EGFP-Luciferase Fused Genes with Wild-Type Parasite

Leishmaniasis is a worldwide uncontrolled parasitic disease due to the lack of effective drug and vaccine. To speed up effective drug development, we need powerful methods to rapidly assess drug effectiveness against the intracellular form of Leishmania in high throughput assays. Reporter gene technology has proven to be an excellent tool for drug screening in vitro. The effects of reporter proteins on parasite infectivity should be identified both in vitro and in vivo. In this research, we initially compared the infectivity rate of recombinant Leishmania major expressing stably enhanced green fluorescent protein (EGFP) alone or EGFP-luciferase (EGFP-LUC) with the wild-type strain. Next, we evaluated the sensitivity of these parasites to amphotericin B (AmB) as a standard drug in 2 parasitic phases, promastigote and amastigote. This comparison was made by MTT and nitric oxide (NO) assay and by quantifying the specific signals derived from reporter genes like EGFP intensity and luciferase activity. To study the amastigote form, both B10R and THP-1 macrophage cell lines were infected in the stationary phase and were exposed to AmB at different time points. Our results clearly revealed that the 3 parasite lines had similar in vitro infectivity rates with comparable parasite-induced levels of NO following interferon-γ/lipopolysaccharide induction. Based on our results we proposed the more reporter gene, the faster and more sensitive evaluation of the drug efficiency.     

Salicylic acid changes morpho-physiological attributes of feverfew (Tanacetum parthenium L.) under salinity stress

Feverfew (Tanacetum parthenium) (TP) is a valuable medicinal plant from Asteraceae family with various pharmaceutical and therapeutic properties. A pot experiment was conducted to evaluate the effect of salicylic acid (SA) on the physiological and morphological responses of TP under salinity stress. Salinity was induced by NaCl and CaCl₂ (2:1) at 30, 60, 90, 120, 150 and 180 mM levels. SA was applied as foliar application at 0, 200 and 300 ppm concentrations. Plant height, leaf and shoot number, fresh and dry weight and essential oil, starch, sugar, protein, proline, catalase (CAT), peroxidase (POD), and ascorbic peroxidase (APX) contents were as measured morpho-physiological traits. The results showed that SA significantly (P ≤ 0.05) improved the measured traits and caused higher tolerance in TP plants under salinity stress. The essential oil content increased with increasing the salinity level up to 90 mM, which was more significant when combined with SA application. All of the measured traits except proline content, antioxidant enzymes, essential oil and sugar decreased at high salinity levels.     

Heavy metals contamination and human health risk assessment in soils of an industrial area,Bandar Abbas – South Central Iran

The purpose of this study was to determine the contamination level, distribution, health risk and potential sources of Cr, Cd, Pb, Zn, Cu, Ni and As in 66 topsoil samples from industrial areas in Bandar Abbas County. The geoaccumulation index, pollution index and pollution load index were calculated to assess the pollution level in the industrial soils. The hazard index and carcinogenic risk were used to assess human health risk of heavy metals. Results showed that the contamination levels of heavy metals were in the descending order of Cu> Cd> Pb> Zn> As> Ni> Cr. Moreover, based on principal component analysis, Cd, Zn, Cu, and Pb originated mainly from anthropogenic sources, including power plants, oil and gas refinery, steel and zinc production factories and municipal waste landfills. For non-carcinogenic effects, hazard index of studied metals decreased in the order of Cr> As> Cd> Pb> Ni > Cu> Zn. Arsenic, chromium and cadmium were regarded as the priority pollutants. Carcinogenic risks due to Cd and As in suburban soils were within tolerable risk to human health; however, children faced more health risk in their daily life than adults via their unconscious ingestion and dermal contact pathway.     

Enhanced chondrogenic differentiation of dental pulp-derived mesenchymal stem cells in 3D pellet culture system: effect of mimicking hypoxia

High incidence of articular cartilage defects resulting from age-related degeneration or trauma injuries is a major problem worldwide. Limited self-regeneration ability of cartilage often leads to inappropriate biochemistry and structure of healed tissue. Considering Impairments of traditional treatments, cell-based therapies are promising. The rapid ex vivo expansion and chondrogenic differentiation capability make dental pulp stem cells (DPSCs) a favorable cell type for therapeutic application, however strategies in order to efficient cartilage tissue-like production are imperative. In the present study the potential role of hypoxia mimicking agent, cobalt chloride (CoCl2), on chondrogenic differentiation of human DPSCs was surveyed. Cell viability assay used to obtain the optimum dose and exposure time of CoCl2. DPSCs were differentiated in pellet culture system after CoCl2 pretreatment. Chondrogenic differentiation efficiency was evaluated by histological and immunohistological analyses. The results showed that CoCl2 led to increased pellet size, integrity and matrix deposition with organizations more resembled typical cartilage lacuna structure. Furthermore, CoCl2 could improve differentiation by elevated chondrogenic markers, glycosaminoglycans (GAGs) and collagen II expression. CoCl2 pretreatment mitigated hypertrophy, as well, which was reflected in decreased collagen X expression. Alkaline phosphatase (ALP) specific activity did not change significantly by CoCl2 preconditioning. Based on current study hypoxia mimicking agent, CoCl2, could be suggested to promote DPSCs chondrogenic differentiation.     

Mitochondrial reactive oxygen is critical for IL-12/IL-18-induced IFN-γ production by CD4+ T cells and is regulated by Fas/FasL signaling

Mitochondrial activation and the production of mitochondrial reactive oxygen species (mROS) are crucial for CD4⁺ T cell responses and have a role in naïve cell signaling after TCR activation. However, little is known about mROS role in TCR-independent signaling and in recall responses. Here, we found that mROS are required for IL-12 plus IL-18-driven production of IFN-γ, an essential cytokine for inflammatory and autoimmune disease development. Compared to TCR stimulation, which induced similar levels of mROS in naïve and memory-like cells, IL-12/IL-18 showed faster and augmented mROS production in memory-like cells. mROS inhibition significantly downregulated IFN-γ and CD44 expression, suggesting a direct mROS effect on memory-like T cell function. The mechanism that promotes IFN-γ production after IL-12/IL-18 challenge depended on the effect of mROS on optimal activation of downstream signaling pathways, leading to STAT4 and NF-κB activation. To relate our findings to IFN-γ-driven lupus-like disease, we used Fas-deficient memory-like CD4⁺ T cells from lpr mice. Importantly, we found significantly increased IFN-γ and mROS production in lpr compared with parental cells. Treatment of WT cells with FasL significantly reduced mROS production and the activation of signaling events leading to IFN-γ. Moreover, Fas deficiency was associated with increased mitochondrial levels of cytochrome C and caspase-3 compared with WT memory-like cells. mROS inhibition significantly reduced the population of disease-associated lpr CD44^hiCD62L^loCD4⁺ T cells and their IFN-γ production. Overall, these findings uncovered a previously unidentified role of Fas/FasL interaction in regulating mROS production by memory-like T cells. This apoptosis-independent Fas activity might contribute to the accumulation of CD44^hiCD62L^loCD4⁺ T cells that produce increased IFN-γ levels in lpr mice. Overall, our findings pinpoint mROS as central regulators of TCR-independent signaling, and support mROS pharmacological targeting to control aberrant immune responses in autoimmune-like disease.Subject terms: Autoimmunity, Cytokines