Transport characteristics of nanoparticle-based ferrofluids in a gel model of the brain

A current advance in nanotechnology is the selective targeting of therapeutics by external magnetic field-guided delivery. This is an important area of research in medicine. The use of magnetic forces results in the formation of agglomerated structures in the field region. The transport characteristics of these agglomerated structures are explored. A nonintrusive method based on in situ light-scattering techniques is used to characterize the velocity of such particles in a magnetic field gradient. A transport model for the chain-like agglomerates is developed based on these experimental observations. The transport characteristics of magnetic nanoparticle drug carriers are then explored in gel-based simulated models of the brain. Results of such measurements demonstrate decreased diffusion of magnetic nanoparticles when placed in a high magnetic field gradient

On the formation and evolution of black-hole binaries

We present the results of a systematic study of the formation and evolution of binaries containing black holes and normal-star companions with a wide range of masses. We first reexamine the standard formation scenario for close black-hole binaries, where the spiral-in of the companion in the envelope of a massive star causes the ejection of the envelope. We estimate the formation rates for different companion masses and different assumptions about the common-envelope structure and other model parameters. We find that black-hole binaries with intermediate- and high-mass secondaries can form for a wide range of assumptions, while black-hole binaries with low-mass secondaries can only form with apparently unrealistic assumptions (in agreement with previous studies). We then present detailed binary evolution sequences for black-hole binaries with secondaries of 2 to 17 Msun and demonstrate that in these systems the black hole can accrete appreciably even if accretion is Eddington limited (up to 7 Msun for an initial black-hole mass of 10 Msun) and that the black holes can be spun up significantly in the process. We discuss the implications of these calculations for well-studied black-hole binaries (in particular GRS 1915+105), ultra-luminous X-ray sources and Cygnus X-1. Finally, we discuss how some of the assumptions in the standard model could be relaxed to allow the formation of low-mass, short-period black-hole binaries which appear to be very abundant in Nature. (Abstract abridged)Comment: 21 pages, 9 figures, accepted by MNRAS, Figs. 2a/2b and 5 in very reduced forma

Validity of a new automated software program for visceral adipose tissue estimation

Introduction: Given the considerable time and research cost of analyzing biomedical images to quantify adipose tissue volumes, automated image analysis methods are highly desirable. Hippo Fatt is a new software program designed to automatically quantify adipose tissue areas from magnetic resonance images without user inputs. Hippo Fatt has yet to be independently validated against commonly used image analysis software programs. Objective: Our aim was to compare estimates of VAT (visceral adipose tissue) and SAT (subcutaneous adipose tissue) using the new Hippo Fatt software against those from a widely used, validated, computer-assisted manual method (slice-O-matic version 4.2, Tomovision, Montreal, CA, USA) to assess its potential utility for large-scale studies. Methods: A Siemens Magnetom Vision 1.5-T whole-body scanner and a T1-weighted fast-spin echo pulse sequence were used to collect multiple, contiguous axial images of the abdomen from a sample of 40 healthy adults (20 men) aged 18-77 years of age, with mean body mass index of 29 kg/m 2 (range ¼ 19-43 kg/m 2 ). Results: Hippo Fatt provided estimates of VAT and SAT that were highly correlated with estimates using slice-O-matic (R 2 40.9). Average VAT was 9.4% lower and average SAT was 3.7% higher using Hippo Fatt compared to slice-O-matic; the overestimation of SAT tended to be greater among individuals with greater adiposity. Individual-level differences for VAT were also substantial; Hippo Fatt gave estimates of VAT ranging from 1184 cm 3 less to 566 cm 3 more than estimates for the same person using slice-O-matic. Conclusion: Hippo Fatt provides a rapid method of quantifying total VAT, although the method does not provide estimates that are interchangeable with slice-O-matic at either the group (mean) or individual level

Signalling versatility following self and non-self sensing by myeloid C-type lectin receptors

AbstractAmong myeloid immune receptors, C-type lectin receptors (CLRs) have a remarkable capacity to sense a variety of self and non-self ligands. The coupling of CLRs to different signal transduction modules is influenced not only by the receptor, but also by the nature, density and architecture of the ligand, which can affect the rate of receptor internalization and trafficking to diverse intracellular compartments. Understanding how the variety of self and non-self ligands triggers differential CLR signalling and function presents a fascinating biological challenge. Non-self ligands usually promote inflammation and immunity, whereas self ligands are frequently involved in communication and tolerance. But pathogens can mimic self-inhibitory signals to escape immune surveillance, and endogenous ligands can contribute to the sensing of pathogens through CLRs. In this review, we survey the complexity and flexibility in functional outcome found in the myeloid CLRs, which is not only based on their differing intracellular motifs, but is also conditioned by the physical nature, affinity and avidity of the ligand

Antisense-Mediated Knockdown of NaV1.8, but Not NaV1.9, Generates Inhibitory Effects on Complete Freund's Adjuvant-Induced Inflammatory Pain in Rat

Tetrodotoxin-resistant (TTX-R) sodium channels NaV1.8 and NaV1.9 in sensory neurons were known as key pain modulators. Comparing with the widely reported NaV1.8, roles of NaV1.9 on inflammatory pain are poorly studied by antisense-induced specific gene knockdown. Here, we used molecular, electrophysiological and behavioral methods to examine the effects of antisense oligodeoxynucleotide (AS ODN) targeting NaV1.8 and NaV1.9 on inflammatory pain. Following complete Freund's adjuvant (CFA) inflammation treatment, NaV1.8 and NaV1.9 in rat dorsal root ganglion (DRG) up-regulated mRNA and protein expressions and increased sodium current densities. Immunohistochemical data demonstrated that NaV1.8 mainly localized in medium and small-sized DRG neurons, whereas NaV1.9 only expressed in small-sized DRG neurons. Intrathecal (i.t.) delivery of AS ODN was used to down-regulate NaV1.8 or NaV1.9 expressions confirmed by immunohistochemistry and western blot. Unexpectedly, behavioral tests showed that only NaV1.8 AS ODN, but not NaV1.9 AS ODN could reverse CFA-induced heat and mechanical hypersensitivity. Our data indicated that TTX-R sodium channels NaV1.8 and NaV1.9 in primary sensory neurons played distinct roles in CFA-induced inflammatory pain and suggested that antisense oligodeoxynucleotide-mediated blocking of key pain modulator might point toward a potential treatment strategy against certain types of inflammatory pain