An atomic force microscope operating at hypergravity for in situ measurement of cellular mechano-response

We present a novel atomic force microscope (AFM) system, operational in liquid at variable gravity, dedicated to image cell shape changes of cells in vitro under hypergravity conditions. The hypergravity AFM is realized by mounting a stand-alone AFM into a large-diameter centrifuge. The balance between mechanical forces, both intra- and extracellular, determines both cell shape and integrity. Gravity seems to be an insignificant force at the level of a single cell, in contrast to the effect of gravity on a complete (multicellular) organism, where for instance bones and muscles are highly unloaded under near weightless (microgravity) conditions. However, past space flights and ground based cell biological studies, under both hypogravity and hypergravity conditions have shown changes in cell behaviour (signal transduction), cell architecture (cytoskeleton) and proliferation. Thus the role of direct or indirect gravity effects at the level of cells has remained unclear. Here we aim to address the role of gravity on cell shape. We concentrate on the validation of the novel AFM for use under hypergravity conditions. We find indications that a single cell exposed to 2 to 3 × g reduces some 30–50% in average height, as monitored with AFM. Indeed, in situ measurements of the effects of changing gravitational load on cell shape are well feasible by means of AFM in liquid. The combination provides a promising technique to measure, online, the temporal characteristics of the cellular mechano-response during exposure to inertial forces

Selenidation of epitaxial silicene on ZrB2

The deposition of elemental Se on epitaxial silicene on ZrB2 thin films was investigated with synchrotron-based core-level photoelectron spectroscopy and low-energy electron diffraction. The deposition of Se at room temperature caused the appearance of Si 2p peaks with chemical shifts of n × 0.51 ± 0.04 eV (n = 1-4), suggesting the formation of SiSe2. This shows that capping the silicene monolayer, without affecting its structural and electronic properties, is not possible with Se. The annealing treatments that followed caused the desorption of Se and Si, resulting in the etching of the Si atoms formerly part of the silicene layer, and the formation of bare ZrB2(0001) surface area. In addition, a ZrB2(0001)-(√7 × 3)R40.9° surface reconstruction was observed, attributed to a Se-termination of the surface of the transition metal diboride thin film

Diet-dependent acid load and type 2 diabetes: pooled results from three prospective cohort studie

Aims/hypothesis: Studies suggest a potential link between low-grade metabolic acidosis and type 2 diabetes. A western dietary pattern increases daily acid load but the association between diet-dependent acid load and type 2 diabetes is still unclear. This study aimed to assess whether diet-dependent acid load is associated with the risk of type 2 diabetes. Methods: We examined the association between energy-adjusted net endogenous acid production (NEAP), potential renal acid load (PRAL) and animal protein-to-potassium ratio (A:P) on incident type 2 diabetes in 67,433 women from the Nurses’ Health Study, 84,310 women from the Nurses’ Health Study II and 35,743 men from the Health Professionals’ Follow-up Study who were free from type 2 diabetes, cardiovascular disease and cancer at baseline. Study-specific HRs were estimated using Cox proportional hazards models with time-varying covariates and were pooled using a random effects meta-analysis. Results: We documented 15,305 cases of type 2 diabetes during 4,025,131 person-years of follow-up. After adjustment for diabetes risk factors, dietary NEAP, PRAL and A:P were positively associated with type 2 diabetes (pooled HR [95% CI] for highest (Q5) vs lowest quintile (Q1): 1.29 [1.22, 1.37], ptrend <0.0001; 1.29 [1.22, 1.36], ptrend <0.0001 and 1.32 [1.24, 1.40], ptrend <0.0001 for NEAP, PRAL and A:P, respectively). These results were not fully explained by other dietary factors including glycaemic load and dietary quality (HR [95% CI] for Q5 vs Q1: 1.21 [1.09, 1.33], ptrend <0.0001; 1.19 [1.08, 1.30] and 1.26 [1.17, 1.36], ptrend <0.0001 for NEAP, PRAL and A:P, respectively). Conclusions/interpretation: This study suggests that higher diet-dependent acid load is associated with an increased risk of type 2 diabetes. This association is not fully explained by diabetes risk factors and overall diet quality