Faculty Bibliography

BACKGROUND AND OBJECTIVES: The predictors of long-term renal function in living kidney donors are currently discussed. Our objectives were to describe the predictors of functional gain of the remaining kidney after kidney donation. We hypothesized that GFR of the remaining kidney divided by volume of this kidney (rk-GFR/vol) would reflect the density of functional nephrons and be inversely associated with functional gain of the remaining kidney. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a prospective monocentric study including 63 living donors (26 men; 50.3+/-11.8 years old) who had been evaluated for 51Cr-EDTA and measured GFR, split renal function by scintigraphy before donation (between 2004 and 2009), and measured GFR at 5.7+/-0.5 years after donation. For 52 donors, volume of the remaining kidney (measured and estimated with the ellipsoid formula using renal computed tomography scannography) was determined before donation. We tested our hypothesis in an external validation cohort of 39 living donors (13 men; 51.0+/-9.4 years old) from another single center during the same time period. RESULTS: For the main cohort, the mean measured GFR was 97.6+/-13.0 ml/min per 1.73 m2 before donation and 63.8+/-9.4 ml/min per 1.73 m2 at 5 years. Functional gain averaged 16.2+/-7.2 ml/min per 1.73 m2 (+35.3%+/-16.7%). Multivariate analysis showed that age, body mass index, and rk-GFR/vol at donation were negatively correlated with functional gain and had strong predictive power of the 5-year functional gain (adjusted 5-year functional gain for age: -0.4 [95% confidence interval (95% CI), -0.5 to -0.1]; body mass index: -0.3 [95% CI, -0.6 to -0.1]; rk-GFR/vol: -55.1 [95% CI, -92.3 to -17.9]). We tested this model in the external validation cohort (adjusted 5-year functional gain for age: -0.1 [95% CI, -0.5 to 0.3]; body mass index: -0.9 [95% CI, -1.8 to -0.1]; rk-GFR/vol: -97.6 [95% CI, -137.5 to -57.6]) and confirmed that rk-GFR/vol was inversely associated with 5-year functional gain. CONCLUSIONS: For given age and body mass index, the long-term functional gain of the remaining kidney is inversely associated with the new variable rk-GFR/vol at donation.

Clinically, many nail disorders accompany bone deformities, but whether the two defects are causally related is under debate. To investigate the potential interactions between the two tissue types, we analyzed epithelial-specific beta-catenin-deficient mice, in which nail differentiation is abrogated. These mice showed regression of not only the nail plate but also of the underlying digit bone. Characterization of these bone defects revealed active bone resorption, which is suppressed by Wnt activation in osteoblast and osteoclast precursors. Furthermore, we found that Wntless expression, essential for Wnt ligand secretion, was lacking in the beta-catenin-deficient nail epithelium and that genetic deletion of Wntless (Wls) in the nail epithelium led to the lack of Wnt activation in osteoblast and osteoclast precursors and subsequently led to defective regression of the underlying digit bone. Together, these data show that epithelial Wnt ligands can ultimately regulate Wnt signaling in osteoblast and osteoclast precursors, known to regulate bone homeostasis. These results reveal a critical role for the nail epithelium on the digit bone during homeostatic regeneration and show that Wnt/beta-catenin signaling is critical for this interaction.

Mechanochromic polymers display detectable changes in their fluorescence emission upon deformation of their macromolecular structure. Here, we study reversible mechanochromism of pyrene functionalized nanocomposite hydrogels. Highly stretchable nanocomposite hydrogels are prepared by free radical polymerization of poly(N-isopropylacrylamide) and pyrene terminated poly(ethylene) glycol methacrylate copolymers in the presence of nanoclay, acting as the physical crosslinker. Mechanochromic behavior is characterized through uniaxial tensile experiments, where force, deformation, and fluorescence emission are simultaneously measured. To demonstrate the application of mechanochromic nanocomposite hydrogels in pressure sensing, membranes are used to detect differential pressures on the order of 10(2) Pa. We envision the integration of these mechanochromic hydrogels in the design of novel force and pressure sensors with application to mechanics, fluid dynamics, and biophysics. (C) 2016 Elsevier B.V. All rights reserved.

As a result of its importance in key RNA metabolic processes, the ribonucleolytic RNA exosome complex has been the focus of intense study for almost two decades. Research on exosome subunit assembly, cofactor and substrate interaction, enzymatic catalysis and structure have largely been conducted using complexes produced in the yeast Saccharomyces cerevisiae or in bacteria. Here, we examine different populations of endogenous exosomes from human embryonic kidney (HEK) 293 cells and test their enzymatic activity and structural integrity. We describe methods to prepare EXOSC10-containing, enzymatically active endogenous human exosomes at suitable yield and purity for in vitro biochemistry and negative stain transmission electron microscopy. This opens the door for assays designed to test the in vitro effects of putative cofactors on human exosome activity and will enable structural studies of preparations from endogenous sources.

OBJECTIVE: The chronic inflammation associated with atherosclerosis is caused by lipid deposition followed by leukocyte recruitment to the arterial wall. We previously showed that the hematopoietic cell-specific adaptor protein Cas- and Hef1-associated signal transducer hematopoietic isoform (Chat-H)/SHEP1 regulated lymphocyte adhesion and migration. In this study, we analyzed the role of Chat-H in atherosclerosis development. APPROACH AND RESULTS: Using Chat-H-deficient bone marrow transplantation in low-density lipoprotein receptor-deficient mice, we found that Chat-H regulated atherosclerotic plaque formation. Chat-H deficiency in hematopoietic cells associated with lower plaque complexity and fewer leukocytes in the lesions, whereas myeloid-specific deletion of Chat-H was sufficient for conferring atheroprotection. Chat-H deficiency resulted in reduced recruitment of classical Ly6chigh and nonclassical Ly6clow monocytes to the plaques, which was accompanied by increased numbers of both monocyte subsets in the blood. This was associated with defective adhesion of Chat-H-deficient Ly6chigh and Ly6clow monocytes to vascular cell adhesion molecule-1 in vitro and impaired infiltration of fluorescent bead-loaded monocytes to atherosclerotic plaques. In contrast, Chat-H was dispensable for CX3CL1 and CCR1/CCR5-dependent migration of monocytes. CONCLUSIONS: Our findings highlight Chat-H as a key protein that regulates atherosclerosis development by controlling monocyte adhesion and recruitment to the plaques and identify a novel target that may be exploited for treating atherosclerosis.

Hunger is a powerful drive that stimulates food intake. Yet, the mechanism that determines how the energy deficits that result in hunger are represented in the brain and promote feeding is not well understood. We previously described SLC5A11-a sodium/solute co-transporter-like-(or cupcake) in Drosophila melanogaster, which is required for the fly to select a nutritive sugar over a sweeter nonnutritive sugar after periods of food deprivation. SLC5A11 acts on approximately 12 pairs of ellipsoid body (EB) R4 neurons to trigger the selection of nutritive sugars, but the underlying mechanism is not understood. Here, we report that the excitability of SLC5A11-expressing EB R4 neurons increases dramatically during starvation and that this increase is abolished in the SLC5A11 mutation. Artificial activation of SLC5A11-expresssing neurons is sufficient to promote feeding and hunger-driven behaviors; silencing these neurons has the opposite effect. Notably, SLC5A11 transcript levels in the brain increase significantly when flies are starved and decrease shortly after starved flies are refed. Furthermore, expression of SLC5A11 is sufficient for promoting hunger-driven behaviors and enhancing the excitability of SLC5A11-expressing neurons. SLC5A11 inhibits the function of the Drosophila KCNQ potassium channel in a heterologous expression system. Accordingly, a knockdown of dKCNQ expression in SLC5A11-expressing neurons produces hunger-driven behaviors even in fed flies, mimicking the overexpression of SLC5A11. We propose that starvation increases SLC5A11 expression, which enhances the excitability of SLC5A11-expressing neurons by suppressing dKCNQ channels, thereby conferring the hunger state.

Myeloid-derived suppressor cells (MDSCs) have emerged as major regulators of immune responses in cancer and other pathological conditions. In recent years, ample evidence supports key contributions of MDSC to tumour progression through both immune-mediated mechanisms and those not directly associated with immune suppression. MDSC are the subject of intensive research with >500 papers published in 2015 alone. However, the phenotypic, morphological and functional heterogeneity of these cells generates confusion in investigation and analysis of their roles in inflammatory responses. The purpose of this communication is to suggest characterization standards in the burgeoning field of MDSC research.

Human infants, like non-human primates, can breathe and swallow simultaneously, due to similarities in the anatomy of the aerodigestive tract (ADT). Morphometric studies lack standardized methods to investigate the descent of the hyolaryngeal apparatus in relation to the skull base and bony Eustachian tube - a process taking place throughout the first three years of postnatal life. This study tests the hypothesis that 3D landmark coordinates taken on sagittal CT scans can be reliably used to assess ADT and craniofacial structures via 3D geometric morphometrics. We used the computer program Osirix to identify 14 landmarks on head and neck sagittal CT scans obtained from 22 monkeys (Macaca mulatta) as a model to test accuracy. After four training sessions on images apart from the study sample, two observers assessed the study sample. Each observer performed three assessments per specimen and no specimen was evaluated twice in the same day. We used Generalized Procrustes Analysis, involving optimal superimposition and scaling by Centroid Size, and measured the procrustes distances to interpret data. Inter-observer errors were significantly high (> 5%), indicating that plotting landmarks on sagittal CTs allows for low reproducibility of measurements via 3D analysis. ANOVA of inter-observer distances per landmark yielded a significant result (p<0.0001), indicating that some landmarks are less reliable, and a series of t-tests with Bonferroni-Dunn adjustment revealed that the craniometric point Prosthion was the least accurate (p<0.05). Tracking the descent of the hyolaryngeal complex relative to craniofacial structures in early postnatal life requires a careful methodological approach. This study indicates that using 3D landmarks obtained from CT sagittal slices to ascertain measurements of the hyoid bone and craniofacial structures situated in different planes yields intrinsic errors of measurements that may jeopardize reproducibility of geometric morphometric analysis. Next step of this project is to use volume rendered 3D CT scans and collect coordinates for the same landmarks to determine interobserver variability, assess accuracy and validate reproducibility