Irregular Heartwood Formation in Maritime Pine (Pinus pinaster Ait):Consequences for Biomechanical and Hydraulic Tree Functioning

As the proportion of sapwood (SW) transformed into heartwood(HW) is irregular both radially and longitudinally in trunksof Maritime pine (Pinus pinaster Ait.), it has been suggestedthat HW formation is a developmental process, regulated internallywithin the tree. In trees where stem growth is eccentric dueto stem lean or wind action, the number of annual growth ringsof SW transformed into HW is greater on the compressed sideof the tree. To determine the contribution to bending stiffness,if any, of this prematurely formed HW, four point bending testswere carried out on fresh HW and SW samples taken from the samegrowth ring, or neighbouring growth rings, at different cross-sectionalpositions at a height of 2 m from six 52-year-old Maritime pines.The mean (±s.e.) modulus of elasticity (E) was 7.6 ±0.3 GPa (longitudinal direction) for all samples. No significantdifferences in E were found between HW and SW; thus HW doesnot play a significant mechanical role in bending stiffness.To test a second hypothesis that early HW formation on the compressedside of trees may maintain a constant, optimal volume of SWaround the tree, the Pipe Model Theory was applied to 12 52-year-oldleaning Maritime pines (angle of lean varied from 0–22°).The surface area (S) of the SW was determined at different heightsup the trunk and correlated with crown surface area (S_crown).Regressions between S_SWandS_crown were highly significant, therebysupporting the theory that HW formation and extension is controlledinternally in Maritime pine. HW formation in Maritime pine thenserves to maintain an optimal proportion of functional SW whichis an important criterion for survival in a species often subjectedto severe drought for long periods. Copyright 2001 Annals ofBotany Company Heartwood, sapwood, bending test, Pipe Model Theory, Pinus pinaster     

A Robust Method of Measuring Other-Race and Other-Ethnicity Effects: The Cambridge Face Memory Test Format

Other-race and other-ethnicity effects on face memory have remained a topic of consistent research interest over several decades, across fields including face perception, social psychology, and forensic psychology (eyewitness testimony). Here we demonstrate that the Cambridge Face Memory Test format provides a robust method for measuring these effects. Testing the Cambridge Face Memory Test original version (CFMT-original; European-ancestry faces from Boston USA) and a new Cambridge Face Memory Test Chinese (CFMT-Chinese), with European and Asian observers, we report a race-of-face by race-of-observer interaction that was highly significant despite modest sample size and despite observers who had quite high exposure to the other race. We attribute this to high statistical power arising from the very high internal reliability of the tasks. This power also allows us to demonstrate a much smaller within-race other ethnicity effect, based on differences in European physiognomy between Boston faces/observers and Australian faces/observers (using the CFMT-Australian).     

Diffusion of extracellular K+ can synchronize bursting oscillations in a model islet of Langerhans.

Electrical bursting oscillations of mammalian pancreatic beta-cells are synchronous among cells within an islet. While electrical coupling among cells via gap junctions has been demonstrated, its extent and topology are unclear. The beta-cells also share an extracellular compartment in which oscillations of K+ concentration have been measured (Perez-Armendariz and Atwater, 1985). These oscillations (1-2 mM) are synchronous with the burst pattern, and apparently are caused by the oscillating voltage-dependent membrane currents: Extracellular K+ concentration (Ke) rises during the depolarized active (spiking) phase and falls during the hyperpolarized silent phase. Because raising Ke depolarizes the cell membrane by increasing the potassium reversal potential (VK), any cell in the active phase should recruit nonspiking cells into the active phase. The opposite is predicted for the silent phase. This positive feedback system might couple the cells' electrical activity and synchronize bursting. We have explored this possibility using a theoretical model for bursting of beta-cells (Sherman et al., 1988) and K+ diffusion in the extracellular space of an islet. Computer simulations demonstrate that the bursts synchronize very quickly (within one burst) without gap junctional coupling among the cells. The shape and amplitude of computed Ke oscillations resemble those seen in experiments for certain parameter ranges. The model cells synchronize with exterior cells leading, though incorporating heterogeneous cell properties can allow interior cells to lead. The model islet can also be forced to oscillate at both faster and slower frequencies using periodic pulses of higher K+ in the medium surrounding the islet. Phase plane analysis was used to understand the synchronization mechanism. The results of our model suggest that diffusion of extracellular K+ may contribute to coupling and synchronization of electrical oscillations in beta-cells within an islet.     

Optimization of permeability in a series of pyrrolotriazine inhibitors of IRAK4

We have developed a series of orally efficacious IRAK4 inhibitors, based on a scaffold hopping strategy and using rational structure based design. Efforts to tackle low permeability and high efflux in our previously reported pyrrolopyrimidine series (Scott et al., 2017) led to the identification of pyrrolotriazines which contained one less formal hydrogen bond donor and were intrinsically more lipophilic. Further optimisation of substituents on this pyrrolotriazine core culminated with the discovery of 30 as a promising in vivo probe to assess the potential of IRAK4 inhibition for the treatment of MyD88 mutant DLBCL in combination with a BTK inhibitor. When tested in an ABC-DLBCL model with a dual MyD88/CD79 mutation (OCI-LY10), 30 demonstrated tumour regressions in combination with ibrutinib.