Publications

Implantable brain electrophysiology probes are valuable tools in neuroscience due to their ability to record neural activity with high spatiotemporal resolution from shallow and deep brain regions. Their use has been hindered, however, by mechanical and structural mismatches between the probes and brain tissue that commonly lead to micromotion and gliosis with resulting signal instability in chronic recording experiments. In contrast, following the implantation of ultraflexible mesh electronics via syringe injection, the mesh probes form a seamless, gliosis-free interface with the surrounding brain tissue that enables stable tracking of individual neurons on at least a year timescale. This protocol details the key steps in a typical mouse neural recording experiment using syringe-injectable mesh electronics, including the fabrication of mesh electronics in a standard photolithography-based process possible at many universities, loading mesh electronics into standard capillary needles, stereotaxic injection in vivo, connection of the mesh input/output to standard instrumentation interfaces, restrained or freely moving recording sessions, and histological sectioning of brain tissue containing mesh electronics. Representative neural recordings and histology data are presented. Investigators familiar with this protocol will have the knowledge necessary to incorporate mesh electronics into their own experiments and take advantage of the unique opportunities afforded by long-term stable neural interfacing, such as studies of aging processes, brain development, and the pathogenesis of brain disease.

OBJECTIVE A1C is widely considered the gold standard for monitoring effective blood glucose levels. Recently, a genome-wide association study reported an association between A1C and rs7072268 within HK1 (encoding hexokinase 1), which catalyzes the first step of glycolysis. HK1 deficiency in erythrocytes (red blood cells [RBCs]) causes severe nonspherocytic hemolytic anemia in both humans and mice. RESEARCH DESIGN AND METHODS The contribution of rs7072268 to A1C and the RBC-related traits was assessed in 6,953 nondiabetic European participants. We additionally analyzed the association with hematologic traits in 5,229 nondiabetic European individuals (in whom A1C was not measured) and 1,924 diabetic patients. Glucose control–related markers other than A1C were analyzed in 18,694 nondiabetic European individuals. A type 2 diabetes case-control study included 7,447 French diabetic patients. RESULTS Our study confirms a strong association between the rs7072268–T allele and increased A1C (β = 0.029%; P = 2.22 × 10−7). Surprisingly, despite adequate study power, rs7072268 showed no association with any other markers of glucose control (fasting- and 2-h post-OGTT–related parameters, n = 18,694). In contrast, rs7072268–T allele decreases hemoglobin levels (n = 13,416; β = −0.054 g/dl; P = 3.74 × 10−6) and hematocrit (n = 11,492; β = −0.13%; P = 2.26 × 10−4), suggesting a proanemic effect. The T allele also increases risk for anemia (836 cases; odds ratio 1.13; P = 0.018). CONCLUSIONS HK1 variation, although strongly associated with A1C, does not seem to be involved in blood glucose control. Since HK1 rs7072268 is associated with reduced hemoglobin levels and favors anemia, we propose that HK1 may influence A1C levels through its anemic effect or its effect on glucose metabolism in RBCs. These findings may have implications for type 2 diabetes diagnosis and clinical management because anemia is a frequent complication of the diabetes state.

Abstract Background Inflammatory processes contribute to the pathophysiology of multiple chronic conditions. Genetic factors play a crucial role in modulating the inflammatory load, but the exact mechanisms are incompletely understood. Methods To add understanding to the molecular mechanisms in inflammation, we performed a genome-wide association study (GWAS) on 16 circulating cytokines and cell adhesion molecules (inflammatory phenotypes) in Northern Finland Birth Cohort 1966 (NFBC1966, N=5,284). A subsequent meta-analysis was completed for 10 phenotypes available in a GWAS of three other Finnish population cohorts adding up to 13,577 individuals in the study. Complementary association tests were performed to study the effect of the ABO blood types on soluble adhesion molecule levels. Results We identified seven novel and confirmed six previously reported loci associating with at least one of the studied inflammatory phenotypes (p<3.1×10 −9 ). We observed three loci associating with the concentration of soluble vascular cell adhesion molecule-1 (sVCAM-1), one of which is the ABO locus that has been previously associated with soluble E-selectin (sE-selectin) and intercellular adhesion molecule-1 (sICAM-1) levels. Results from the complementary analyses suggest that the blood type B associates primarily with the concentration of sVCAM-1 while the A1 subtype shows a robust effect on sE-selectin and sICAM-1 levels. Furthermore, the genotypes in the ABO locus associating with higher soluble adhesion molecule levels tend to associate with lower low-density lipoprotein cholesterol level and lower cardiovascular disease risk. Conclusion The present results extend the knowledge about genetic factors contributing to the inflammatory load. Our findings suggest that two distinct mechanisms contribute to the soluble adhesion molecule levels at the ABO locus. The negative correlation between the genetic effects on soluble adhesion molecule levels and cardiovascular traits in this locus further suggests that increased soluble adhesion molecule levels per se may not be a risk factor for cardiovascular disease.

It's the water that matters. Pairs of benzo- and perfluorobenzoarylsulfonamide ligands bind to human carbonic anhydrase with a conserved binding geometry, an enthalpy-driven binding, and indistinguishable binding affinities (see picture). These data support the pervasive theory that the lock-and-key model disregards an important component of binding: the water, which fills the binding pocket of the protein and surrounds the ligand. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A mendelian randomization study based on data from multiple cohorts conducted by Karani Santhanakrishnan Vimaleswaran and colleagues re-examines the causal nature of the relationship between vitamin D levels and obesity.

Carbon nanotubes are potentially ideal atomic force microscopy (AFM) probes due to their well-defined geometry, robust mechanical properties, and in the case of single-walled nanotubes (SWNTs), diameters approaching the size of small organic molecules. Here we elucidate fundamental factors that determine AFM imaging resolution using a combination of experiments with well-characterized SWNT probes and numerical simulations. Tapping mode AFM imaging on gold nanoclusters and DNA molecules using SWNT probes shows that the tip-induced broadening reaches the geometrical limit (i.e., the diameter of the SWNT tips) in the repulsive imaging regime, and the broadening effect becomes greater than the geometrical limit in the attractive imaging regime due to long-range attractive forces. Adjusting the damping enables imaging of isolated DNA molecules with a resolution defined by the tip diameter without disrupting the sample.

Local physical interactions between cells and extracellular matrix (ECM) influence directional cell motility that is critical for tissue development, wound repair, and cancer metastasis. Here we test the possibility that the precise spatial positioning of focal adhesions governs the direction in which cells spread and move. NIH 3T3 cells were cultured on circular or linear ECM islands, which were created using a microcontact printing technique and were 1 microm wide and of various lengths (1 to 8 microm) and separated by 1 to 4.5 microm wide nonadhesive barrier regions. Cells could be driven proactively to spread and move in particular directions by altering either the interisland spacing or the shape of similar-sized ECM islands. Immunofluorescence microscopy confirmed that focal adhesions assembled preferentially above the ECM islands, with the greatest staining intensity being observed at adhesion sites along the cell periphery. Rac-FRET analysis of living cells revealed that Rac became activated within 2 min after peripheral membrane extensions adhered to new ECM islands, and this activation wave propagated outward in an oriented manner as the cells spread from island to island. A computational model, which incorporates that cells preferentially protrude membrane processes from regions near newly formed focal adhesion contacts, could predict with high accuracy the effects of six different arrangements of micropatterned ECM islands on directional cell spreading. Taken together, these results suggest that physical properties of the ECM may influence directional cell movement by dictating where cells will form new focal adhesions and activate Rac and, hence, govern where new membrane protrusions will form.

Episodic breakdown: The dynamics of contact electrification of a metal sphere rolling across an insulating plate are investigated. The data are consistent with contact charging that involves the transfer of ions (see picture), interrupted by episodic discharge events that involve the dielectric breakdown of air. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z802062_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Das Titelbild zeigt eine Hg-SAM1//SAM2-Ag-Nanoschnittstelle, mit der eine Vielzahl an selbstorganisierten Monoschichten (SAMs) auf ihre elektronischen Eigenschaften untersucht werden kann. Der Aufbau dieser molekularen Schnittstelle, die aus einer Quecksilberelektrode mit der SAM1 (oben) und einem silberbeschichteten Siliciumwafer mit der SAM2 (unten) besteht, ist einfach und erlaubt das schnelle Screening unterschiedlich funktionalisierter Monoschichten. Im Bild erkennt man eine Grenzflächenreflexion (ein Spiegelbild) des Quecksilbertropfens an der unteren Silberschicht. In dieser Messanordnung wurden die elektronischen Eigenschaften einer Reihe von aromatischen und terminal funktionalisierten SAMs gemessen; diese wurden dann mit der molekularen Struktur der jeweiligen SAM korreliert. Einzelheiten über diese Nanoschnittstelle finden sich im Beitrag von M. A. Rampi, G. M. Whitesides et al. auf S. 2378 ff.