Show Abstract ▼

Abstract: Metabolic bone diseases have an impact on the multi-scale structure of bone and its mechanical properties. This study aims to conduct quantitative analysis of the link between specific material-level changes and mechanical alterations of bone tissue. We combine several scanning probe methods with an analytical multiscale model to investigate these links in a mouse model (𝐶𝑟h−120∕+) with endogenous steroid production. Experimental results from our prior study are used, which showed significant changes in spatial maps of nano-scale orientation, mineralization, and microporosity in 𝐶𝑟h−120∕+ mice bone. An analytical composite/continuum mechanical model is incorporated with these experimental parameters to predict the progressive reduction in elastic moduli. The largest fractional reduction in elastic modulus is found to arise from incorporation of microscale porosity, followed by the reduced nanoscale degree of orientation. Our work provides both insights into the altered structure-performance relations and a systematic analytical framework for linking scanning micro- and nanoprobe experimental data on hierarchical structural materials to macroscopic biomechanical outcomes.

Open Access

Show Abstract ▼

Abstract: Transition metal complexes are often prodrugs which undergo activation by ligand exchange and redox reactions before they interact with target sites. It is therefore important to understand the roles of both the metal and the ligands in their activation, especially in cells. Here we use a combination of synchrotron nanoprobe X-ray fluorescence (XRF) from Os L3M5 and Br KL3 emissions and inductively coupled plasma-mass spectrometry (ICP-MS) detection of 189Os, 79Br, and 127I, to investigate the time-dependent accumulation and localization of osmium as well as the monodentate ligand and the chelated phenylazopyridine in A2780 human ovarian cancer cells treated with the potent anticancer complexes [Os(η6-p-cymene)(4-R2-phenyl-azopyridine-5-R1)X]PF6, with R2 = NMe2 or OH, R1 = H or Br, and X = Cl or I. The data confirm that the relatively inert iodido complexes are activated rapidly in cancer cells by release of the iodido ligand, probably initiated by attack by the intracellular tripeptide glutathione (γ-L-Glu-l-Cys-Gly) on the azo double bond. The bond between osmium and the azopyridine appears to remain stable in cells for ca. 24 h, although some release of the chelated ligand is observed. Interestingly, the complexes seem to be degraded more rapidly in normal human cells, perhaps providing a possible mechanism for selective cytotoxicity towards cancer cells.

Open Access

Show Abstract ▼

Abstract: The chemistry of copper and iron plays a critical role in normal brain function. A variety of enzymes and proteins containing positively charged Cu+, Cu2+, Fe2+, and Fe3+ control key processes, catalyzing oxidative metabolism and neurotransmitter and neuropeptide production. Here, we report the discovery of elemental (zero–oxidation state) metallic Cu0 accompanying ferromagnetic elemental Fe0 in the human brain. These nanoscale biometal deposits were identified within amyloid plaque cores isolated from Alzheimer’s disease subjects, using synchrotron x-ray spectromicroscopy. The surfaces of nanodeposits of metallic copper and iron are highly reactive, with distinctly different chemical and magnetic properties from their predominant oxide counterparts. The discovery of metals in their elemental form in the brain raises new questions regarding their generation and their role in neurochemistry, neurobiology, and the etiology of neurodegenerative disease.

Open Access

Show Abstract ▼

Abstract: Background/Introduction: Breast microcalcifications are deposits of calcium oxalate, found mostly in benign tissue, or calcium phosphate in the form of hydroxyapatite, found in benign and malignant tissue. Differences in the crystallographic properties and chemical make-up of hydroxyapatite breast microcalcifications have previously been noted in differing breast pathologies. Purpose: Ductal carcinoma in-situ (DCIS) is a precancerous breast lesion, which has the potential to form invasive breast cancer. Currently there are no definitive markers to determine DCIS invasiveness, therefore this work aims to elucidate differences in the calcification chemistry between invasive and non-invasive cases of DCIS, ultimately developing a novel biomarker for DCIS progression. Methods: 75 formalin fixed paraffin embedded archive breast tissue samples were used subject to NHS REC approval (ref. 18/LO/0945). X-ray diffraction was carried out at 12keV on beamline i18 at Diamond Light Source, UK to determine crystallographic properties of 279 breast calcifications. SEM-EDS experiments were carried out on a Hitachi SU3500 at 11kV under low vacuum. Results: Significant differences (P < 0.05) were observed in the proportion of magnesium whitlockite found as a secondary phase in breast calcifications from invasive (3.51 %) and non-invasive (2.82 %) DCIS samples. Additionally, crystallographic features of hydroxyapatite, the bulk of calcifications in both cases, were found to differ between the two groups. The d-spacing between crystallographic planes, was significantly (P < 0.001) larger in invasive compared to non-invasive DCIS cases. Finally, the calcium to phosphate ratio measured using EDS was significantly lower (P < 0.001) in invasive samples (1.60) compared to non-invasive samples (1.67), which more closely reflected stoichiometric hydroxyapatite. Conclusion(s): Differences in calcification chemistry and crystallographic structure between invasive and non-invasive DCIS cases have been demonstrated in this study. Therefore, calcification chemistry is a key candidate for novel DCIS progression biomarkers and could ultimately lower treatment expenditure and improve patient quality of life by reducing overtreatment.

Open Access

Show Abstract ▼

Abstract: The inhibition of the nuclear receptor retinoic-acid-receptor-related orphan receptor γt (RORγt) is a promising strategy in the treatment of autoimmune diseases. RORγt features an allosteric binding site within its ligand-binding domain that provides an opportunity to overcome drawbacks associated with orthosteric modulators. Recently, trisubstituted isoxazoles were identified as a novel class of allosteric RORγt inverse agonists. This chemotype offers new opportunities for optimization into selective and efficacious allosteric drug-like molecules. Here, we explore the structure–activity relationship profile of the isoxazole series utilizing a combination of structure-based design, X-ray crystallography, and biochemical assays. The initial lead isoxazole (FM26) was optimized, resulting in compounds with a ∼10-fold increase in potency (low nM), significant cellular activity, promising pharmacokinetic properties, and a good selectivity profile over the peroxisome-proliferated-activated receptor γ and the farnesoid X receptor. We envisage that this work will serve as a platform for the accelerated development of isoxazoles and other novel chemotypes for the effective allosteric targeting of RORγt.