Citations

Abstract NK cells provide host defense by killing viral-infected and cancerous cells through the secretion of preformed lytic granules. Polarization of the lytic granules toward the target cell is dependent on an intact microtubule (MT) network as well as MT motors. We have recently shown that DOCK8, a gene mutated in a primary immunodeficiency syndrome, is involved in NK cell killing in part through its effects on MT organizing center (MTOC) polarization. In this study, we identified Hook-related protein 3 (HkRP3) as a novel DOCK8- and MT-binding protein. We further show that HkRP3 is present in lytic granule fractions and interacts with the dynein motor complex and MTs. Significantly, depletion of HkPR3 impaired NK cell cytotoxicity, which could be attributed to a defect in not only MTOC polarity, but also impaired clustering of lytic granules around the MTOC. Our results demonstrate an important role for HkRP3 in regulating the clustering of lytic granules and MTOC repositioning during the development of NK cell–mediated killing.

Background— Implanting centers often require the identification of a dedicated caregiver before destination therapy left ventricular assist device (DT LVAD) implantation; however, the caregiver experience surrounding this difficult decision is relatively unexplored. Methods and Results— From October 2012 through July 2013, we conducted semistructured, in-depth interviews with caregivers of patients considering DT LVAD. Data were analyzed using a mixed inductive and deductive approach. We interviewed 17 caregivers: 10 caregivers of patients living with DT LVAD, 6 caregivers of patients who had died with DT LVAD, and 1 caregiver of a patient who had declined DT LVAD. The themes identified, which could also be considered dialectical tensions, are broadly interpreted under 3 domains mapping to decision context, process, and outcome: (1) the stark decision context, with tension between hope and reality; (2) the challenging decision process, with tension between wanting loved ones to live and wanting to respect loved ones’ wishes; and (3) the downstream decision outcome, with tension between gratitude and burden. Conclusions— Decision-making surrounding DT LVAD should incorporate decision support for patients and caregivers. This should include a focus on caregiver burden and the predictable tensions that caregivers experience.

Abstract Family-based study design is commonly used in genetic research. It has many ideal features, including being robust to population stratification (PS). With the advance of high-throughput technologies and ever-decreasing genotyping cost, it has become common for family studies to examine a large number of variants for their associations with disease phenotypes. The yield from the analysis of these family-based genetic data can be enhanced by adopting computationally efficient and powerful statistical methods. We propose a general framework of a family-based U-statistic, referred to as family-U, for family-based association studies. Unlike existing parametric-based methods, the proposed method makes no assumption of the underlying disease models and can be applied to various phenotypes (e.g., binary and quantitative phenotypes) and pedigree structures (e.g., nuclear families and extended pedigrees). By using only within-family information, it can offer robust protection against PS. In the absence of PS, it can also utilize additional information (i.e., between-family information) for power improvement. Through simulations, we demonstrated that family-U attained higher power over a commonly used method, family-based association tests, under various disease scenarios. We further illustrated the new method with an application to large-scale family data from the Framingham Heart Study. By utilizing additional information (i.e., between-family information), family-U confirmed a previous association of CHRNA5 with nicotine dependence.

The mechanism of heme oxygenase-1 gene ( ho-1) activation by heme in immortalized rat proximal tubular epithelial cells was examined. Analysis of the ho-1promoter identified the heme-responsive sequences as the stress-response element (StRE), multiple copies of which are present in two enhancer regions, E1 and E2. Electrophoretic mobility shift assays identified Nrf2, MafG, ATF3, and Jun and Fos family members as StRE-binding proteins; binding of Nrf2, MafG, and ATF3 was increased in response to heme. Dominant-negative mutants of Nrf2 and Maf, but not of c-Fos and c-Jun, inhibited basal and heme-induced expression of an E1-controlled luciferase gene. Heme did not affect the transcription activity of Nrf2, dimerization between Nrf2 and MafG, or the level of MafG, but did stimulate expression of Nrf2. Heme did not influence the level of Nrf2 mRNA but increased the half-life of Nrf2 protein from ∼10 min to nearly 110 min. These results indicate that heme promotes stabilization of Nrf2, leading to accumulation of Nrf2 · MafG dimers that bind to StREs to activate the ho-1 gene.

Revision total hip arthroplasty (THA) is challenging when there is severe loss of bone in the proximal femur. The purpose of this study was to evaluate the clinical and radiographic outcomes of revision THA in patients with severe proximal femoral bone loss treated with a fluted, tapered, modular femoral component. Between January 1998 and December 2004, 92 revision THAs were performed in 92 patients using a single fluted, tapered, modular femoral stem design. Pre-operative diagnoses included aseptic loosening, infection and peri-prosthetic fracture. Bone loss was categorised pre-operatively as Paprosky types III-IV, or Vancouver B3 in patients with a peri-prosthetic fracture. The mean clinical follow-up was 6.4 years (2 to 12). A total of 47 patients had peri-operative complications, 27 of whom required further surgery. However, most of these further operations involved retention of a well-fixed femoral stem, and 88/92 femoral components (97%) remained in situ. Of the four components requiring revision, three were revised for infection and were well fixed at the time of revision; only one (1%) was revised for aseptic loosening. The most common complications were post-operative instability (17 hips, 19%) and intra-operative femoral fracture during insertion of the stem (11 hips, 12%). Diaphyseal stress shielding was noted in 20 hips (22%). There were no fractures of the femoral component. At the final follow-up 78% of patients had minimal or no pain.Revision THA in patients with extensive proximal femoral bone loss using the Link MP fluted, tapered, modular stem led to a high rate of osseointegration of the stem at mid-term follow-up.Cite this article: Bone Joint J 2015; 97-B:312–17.

Multiple pulmonary conditions are characterized by an abnormal misbalance between various tissue components, for example, an increase in the fibrous connective tissue and loss/increase in extracellular matrix proteins (ECM). Such tissue remodeling may adversely impact physiological function of airway smooth muscle cells (ASMCs) responsible for contraction of airways and release of a variety of bioactive molecules. However, few efforts have been made to understand the potentially significant impact of tissue remodeling on ASMCs. Therefore, this study reports how ASMCs respond to a change in mechanical stiffness of a matrix, to which ASMCs adhere because mechanical stiffness of the remodeled airways is often different from the physiological stiffness. Accordingly, using atomic force microscopy (AFM) measurements, we found that the elastic modulus of the mouse bronchus has an arithmetic mean of 23.1 ± 14 kPa (SD) (median 18.6 kPa). By culturing ASMCs on collagen-conjugated polyacrylamide hydrogels with controlled elastic moduli, we found that gels designed to be softer than average airway tissue significantly increased cellular secretion of vascular endothelial growth factor (VEGF). Conversely, gels stiffer than average airways stimulated cell proliferation, while reducing VEGF secretion and agonist-induced calcium responses of ASMCs. These dependencies of cellular activities on elastic modulus of the gel were correlated with changes in the expression of integrin-β1 and integrin-linked kinase (ILK). Overall, the results of this study demonstrate that changes in matrix mechanics alter cell proliferation, calcium signaling, and proangiogenic functions in ASMCs.

The ocular motor system provides several advantages for studying the brain, including well‐defined populations of neurons that contribute to specific eye movements. Generation of rapid eye movements (saccades) depends on excitatory burst neurons (EBN) and omnipause neurons (OPN) within the brainstem, both types of cells are highly active. Experimental lesions of EBN and OPN cause slowing or complete loss of saccades. We report a patient who developed a permanent, selective saccadic palsy following cardiac surgery. When she died several years later, surprisingly, autopsy showed preservation of EBN and OPN. We therefore considered other mechanisms that could explain her saccadic palsy. Recent work has shown that both EBN and OPN are ensheathed by perineuronal nets (PN), which are specialized extracellular matrix structures that may help stabilize synaptic contacts, promote local ion homeostasis, or play a protective role in certain highly active neurons. Here, we review the possibility that damage to PN, rather than to the neurons they support, could lead to neuronal dysfunction—such as saccadic palsy. We also suggest how future studies could test this hypothesis, which may provide insights into the vulnerability of other active neurons in the nervous system that depend on PN.