Thyroid hormone transport by the heterodimeric human system L amino acid transporter

Transport of thyroid hormone across the cell membrane is required for thyroid hormone action and metabolism. We have investigated the possible transport of iodothyronines by the human system L amino acid transporter, a protein consisting of the human 4F2 heavy chain and the human LAT1 light chain. Xenopus oocytes were injected with the cRNAs coding for human 4F2 heavy chain and/or human LAT1 light chain, and after 2 d were incubated at 25 C with 0.01-10 microM [(125)I]T(4), [(125)I]T(3), [(125)I]rT(3), or [(125)I]3,3'-diiodothyronine or with 10-100 microM [(3)H]arginine, [(3)H]leucine, [(3)H]phenylalanine, [(3)H]tyrosine, or [(3)H]tryptophan. Injection of human 4F2 heavy chain cRNA alone stimulated the uptake of leucine and arginine due to dimerization of human 4F2 heavy chain with an endogenous Xenopus light chain, but did not affect the uptake of other ligands. Injection of human LAT1 light chain cRNA alone did not stimulate the uptake of any ligand. Coinjection of cRNAs for human 4F2 heavy chain and human LAT1 light chain stimulated the uptake of phenylalanine > tyrosine > leucine > tryptophan (100 microM) and of 3,3'-diiodothyronine > rT(3) approximately T(3) > T(4) (10 nM), which in all cases was Na(+) independent. Saturation analysis provided apparent Michaelis constant (K(m)) values of 7.9 microM for T(4), 0.8 microM for T(3), 12.5 microM for rT(3), 7.9 microM for 3,3'-diiodothyronine, 46 microM for leucine, and 19 microM for tryptophan. Uptake of leucine, tyrosine, and tryptophan (10 microM) was inhibited by the different iodothyronines (10 microM), in particular T(3). Vice versa, uptake of 0.1 microM T(3) was almost completely blocked by coincubation with 100 microM leucine, tryptophan, tyrosine, or phenylalanine. Our results demonstrate stereospecific Na(+)-independent transport of iodothyronines by the human heterodimeric system L amino acid transporter

PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al

Small business economics: A perspective from The Netherlands

In the analysis of economic phenomena either within or across industries there is room for integrating the role of small business. This contribution can be made by aggregation or generalization of the findings at the meso level, which again are partly based upon analyses at the micro level. The Netherlands has a long history in macro model building. A recent discussion among Dutch macro-economists considered the future of econometric model building at the macro level, and considered how best to improve this model building. The explicit integration of scale effects, however, was not mentioned. I am convinced that improvements in this respect are possible. In particular, I have in mind the role which small businesses play in certain areas such as wage structure, employment or investments. The dissection of macro prognoses into a small business component and a remaining component is a traditional practice in The Netherlands.1 Finally, there is much concern in The Netherlands for the calculation of regulatory effects, decomposed into effects for small and large businesses. If anywhere in the world there is a solid foundation for studying scale effects in both macro and sectoral models, it most certainly has been in The Netherlands. There is a strong tradition of macro-econometric model building; groups of econometricians specialized in small business research exist; Dutch policymakers show concern and the required research apparatus is available

USH2A is a Meissner’s corpuscle protein necessary for normal vibration sensing in mice and humans

Fingertip mechanoreceptors comprise sensory neuron endings together with specialized skin cells that form the end-organ. Exquisitely sensitive, vibration-sensing neurons are associated with Meissner’s corpuscles in the skin. In the present study, we found that USH2A, a transmembrane protein with a very large extracellular domain, was found in terminal Schwann cells within Meissner’s corpuscles. Pathogenic USH2A mutations cause Usher’s syndrome, associated with hearing loss and visual impairment. We show that patients with biallelic pathogenic USH2A mutations also have clear and specific impairments in vibrotactile touch perception, as do mutant mice lacking USH2A. Forepaw rapidly adapting mechanoreceptors innervating Meissner’s corpuscles, recorded from Ush2a−/− mice, showed large reductions in vibration sensitivity. However, the USH2A protein was not found in sensory neurons. Thus, loss of USH2A in corpuscular end-organs reduced mechanoreceptor sensitivity as well as vibration perception. Thus, a tether-like protein is required to facilitate detection of small-amplitude vibrations essential for the perception of fine-grained tactile surfaces.The present study was funded by grants from the Deutsche Forschungsgemeinshaft (grant nos. SFB665-B6 to G.R.L., SFB1315 to J.F.A.P. and SFB1158-A01 to S.G.L.) and grants from the European Research Council (grant nos. 789128 to G.R.L. and ERC-2015-CoG-682422 to J.F.A.P.). Additional funding was from the Institute of Health Carlos III (Spanish Ministry of Science and Innovation, grant no. FIS PI16/00539 to J.M.).Peer reviewe

Integrating geomatics in archaeological research at the site of Thorikos (Greece)

Archaeological excavation is a destructive process, making accurate, fast and efficient 3D documentation of information essential. With this in mind, our research uses an integrated workflow of topographic measurements and image-based 3D modelling to generate highly accurate reconstructions of archaeological features at the site of Thorikos, Greece. Topographic ground control points and images are acquired using a total station and consumer digital camera respectively, and processed in a highly automated workflow using Structure from Motion and Multiview Stereo reconstruction software. These models were generated on a daily basis in order to map the on-going of a field campaign at this archaeological site in 2012. Moreover, a management system is presented as a consultation and analysis application, enabling the interaction with the 3D models, accompanied with attribute data and metadata. For the efficiency of the management system it was essential to integrate the 3D models in a Harris matrix. This matrix functions as an intermediate between a graphical user interface and the database system. Additionally, two applications of these 3D models are presented, focussing on capacity calculations and in situ mapping (orthophoto mapping) of stone wall remains. The presented management system, the linking of 3D models with excavation data, and the use of 3D models as a scientific tool demonstrate the huge potential of 3D data for archaeological research

Integrating geomatics in archaeological research at the site of Thorikos (Greece)

Archaeological excavation is a destructive process, making accurate, fast and efficient 3D documentation of information essential. With this in mind, our research uses an integrated workflow of topographic measurements and image-based 3D modelling to generate highly accurate reconstructions of archaeological features at the site of Thorikos, Greece. Topographic ground control points and images are acquired using a total station and consumer digital camera respectively, and processed in a highly automated workflow using Structure from Motion and Multiview Stereo reconstruction software. These models were generated on a daily basis in order to map the on-going of a field campaign at this archaeological site in 2012. Moreover, a management system is presented as a consultation and analysis application, enabling the interaction with the 3D models, accompanied with attribute data and metadata. For the efficiency of the management system it was essential to integrate the 3D models in a Harris matrix. This matrix functions as an intermediate between a graphical user interface and the database system. Additionally, two applications of these 3D models are presented, focussing on capacity calculations and in situ mapping (orthophoto mapping) of stone wall remains. The presented management system, the linking of 3D models with excavation data, and the use of 3D models as a scientific tool demonstrate the huge potential of 3D data for archaeological research

Hyperprealbuminemia, euthyroid hyperthyroxinemia, Zollinger-Ellison-like syndrome and hypercorticism in a pancreatic endocrine tumour

Prealbumin, one of the main thyroxine transport proteins, has recently been shown to be a valuable immunohistochemical marker of neuroendocrine tumours. We report the case of a multisecretory pancreatic endocrine tumour whose prealbumin secretion was so high that it produced a peak on routine serum protein electrophoresis and induced a euthyroid hyperthyroxinemia. The maximal binding capacity of prealbumin for thyroxine was indeed markedly increased, whereas its affinity for this hormone was normal. The tumour was associated with gastric hyperacidity and hypergastrinemia thereby evoking a Zollinger-Ellison syndrome. The secretin stimulation test and gastrin tumoural immunohistochemistry were, however, negative. We suggest that the concomitant tumoural production of gastrin-releasing peptide was responsible for the gastric hyperacidity and hypergastrinemia. This hormone probably also accounted for a moderate hypercorticism