Side‐chain dynamics of the <scp>α_1B‐</scp>adrenergic receptor determined by <scp>NMR</scp> via methyl relaxation

G protein‐coupled receptors (GPCRs) are medically important membrane proteins that sample inactive, intermediate, and active conformational states characterized by relatively slow interconversions (~μs–ms). On a faster timescale (~ps–ns), the conformational landscape of GPCRs is governed by the rapid dynamics of amino acid side chains. Such dynamics are essential for protein functions such as ligand recognition and allostery. Unfortunately, technical challenges have almost entirely precluded the study of side‐chain dynamics for GPCRs. Here, we investigate the rapid side‐chain dynamics of a thermostabilized α$_{1B}$‐adrenergic receptor (α$_{1B}$‐AR) as probed by methyl relaxation. We determined order parameters for Ile, Leu, and Val methyl groups in the presence of inverse agonists that bind orthosterically (prazosin, tamsulosin) or allosterically (conopeptide ρ‐TIA). Despite the differences in the ligands, the receptor's overall side‐chain dynamics are very similar, including those of the apo form. However, ρ‐TIA increases the flexibility of Ile176$^{4×56}$ and possibly of Ile214$^{5×49}$, adjacent to Pro215$^{5×50}$ of the highly conserved P$^{5×50}$I$^{3×40}$F$^{6×44}$ motif crucial for receptor activation, suggesting differences in the mechanisms for orthosteric and allosteric receptor inactivation. Overall, increased Ile side‐chain rigidity was found for residues closer to the center of the membrane bilayer, correlating with denser packing and lower protein surface exposure. In contrast to two microbial membrane proteins, in α$_{1B}$‐AR Leu exhibited higher flexibility than Ile side chains on average, correlating with the presence of Leu in less densely packed areas and with higher protein‐surface exposure than Ile. Our findings demonstrate the feasibility of studying receptor‐wide side‐chain dynamics in GPCRs to gain functional insights

Factors predictive of acute renal failure and need for hemodialysis among ED patients with rhabdomyolysis

Objective: We assessed the primary causes of rhabdomyolysis, the factors associated with the development of acute renal failure (ARF), and the need for hemodialysis (HD) among a series of patients presenting to an urban emergency department with rhabdomyolysis. Methods: A chart review between January 1992 and December 1995 was conducted of patients aged 18 years or older with a diagnosis of rhabdomyolysis and an initial serum creatine phosphokinase greater than 1000 U/L. Patients were excluded if they had evidence of myocardial ischemia, cerebrovascular insufficiency, or the development of rhabdomyolysis after hospitalization. Demographic information, presumed causative factors, past medical history, medication usage, and laboratory data were collected. Results: Ninety-seven patients (93 men, 4 women) were enrolled, with a mean age of 35.7 years. The most common causes of rhabdomyolysis were cocaine (30), exercise (29), and immobilization (18). Seventeen of 97 (17.5%) patients developed ARF; 8 patients (8.25%) needed HD. Several clinical and laboratory factors were statistically associated with development of ARF and need for HD. The only variable that was predictive of both ARF and need for HD in separate multivariate regression models was the initial creatinine (Cr). Initial blood urea nitrogen also was predictive of the need for HD. No patient developed ARF with an initial Cr less than 1.7 mg/dL. Conclusion: Acute renal failure and need for HD are common complications of rhabdomyolysis. Except for initial serum Cr and blood urea nitrogen, clinical and laboratory factors were not reliable predictors for the development of ARF or need for HD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40388/1/Fernandez_Factors predictive of acute renal failure_2005.pd

Behavioural resistance against a protozoan parasite in the monarch butterfly

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89483/1/j.1365-2656.2011.01901.x.pd

Attenuation of RNA polymerase II pausing mitigates BRCA1-associated R-loop accumulation and tumorigenesis.

Most BRCA1-associated breast tumours are basal-like yet originate from luminal progenitors. BRCA1 is best known for its functions in double-strand break repair and resolution of DNA replication stress. However, it is unclear whether loss of these ubiquitously important functions fully explains the cell lineage-specific tumorigenesis. In vitro studies implicate BRCA1 in elimination of R-loops, DNA-RNA hybrid structures involved in transcription and genetic instability. Here we show that R-loops accumulate preferentially in breast luminal epithelial cells, not in basal epithelial or stromal cells, of BRCA1 mutation carriers. Furthermore, R-loops are enriched at the 5' end of those genes with promoter-proximal RNA polymerase II (Pol II) pausing. Genetic ablation of Cobra1, which encodes a Pol II-pausing and BRCA1-binding protein, ameliorates R-loop accumulation and reduces tumorigenesis in Brca1-knockout mouse mammary epithelium. Our studies show that Pol II pausing is an important contributor to BRCA1-associated R-loop accumulation and breast cancer development

Families' experiences of raising concerns in health care services: an interpretative phenomenological analysis

Background This exploratory study aimed to increase understanding of the experiences of families of people with intellectual disabilities when noticing and raising concerns in services. A qualitative design was employed. Methods Seven participants (all female) were recruited through local and national voluntary agencies; five were mothers of people with intellectual disabilities, one was the aunt and one the sister. Participants took part in semi structured interviews centred on their experiences of noticing and raising concerns, these were recorded and transcribed. The data was analyzed using Interpretative Phenomenological Analysis (IPA; Smith, 1996). Results The data was grouped into three superordinate themes: the nature and importance of concerns, relationships between families and staff and the process of raising concerns. A key and surprising finding was the importance of ‘the little things’. Conclusions This research highlights important implications for services such as the need to simplify the process of raising concerns, attend to the relationship with families and ensure advocacy services are identified for those without family

On the dynamics of planetesimals embedded in turbulent protoplanetary discs with dead zones

(abridged) Accretion in protoplanetary discs is thought to be driven by [...] turbulence via the magnetorotational instability (MRI). Recent work has shown that a planetesimal swarm embedded in a fully turbulent disc is subject to strong excitation of the velocity dispersion, leading to collisional destruction of bodies with radii R_p < 100 km. Significant diffusion of planetesimal semimajor axes also arises, leading to large-scale spreading of the planetesimal population throughout the inner regions of the protoplanetary disc, in apparent contradiction of constraints provided by the distribution of asteroids within the asteroid belt. In this paper, we examine the dynamics of planetesimals embedded in vertically stratified turbulent discs, with and without dead zones. Our main aims are to examine the turbulent excitation of the velocity dispersion, and the radial diffusion, of planetesimals in these discs. We employ three dimensional MHD simulations [...], along with an equilibrium chemistry model [...] We find that planetesimals in fully turbulent discs develop large random velocities that will lead to collisional destruction/erosion for bodies with sizes below 100 km, and undergo radial diffusion on a scale \sim 2.5 au over a 5 Myr disc life time. But planetesimals in a dead zone experience a much reduced excitation of their random velocities, and equilibrium velocity dispersions lie between the disruption thresholds for weak and strong aggregates for sizes R_p < 100 km. We also find that radial diffusion occurs over a much reduced length scale \sim 0.25 au over the disc life time, this being consistent with solar system constraints. We conclude that planetesimal growth via mutual collisions between smaller bodies cannot occur in a fully turbulent disc. By contrast, a dead zone may provide a safe haven in which km-sized planetesimals can avoid mutual destruction through collisions.Comment: 18 pages, 13 figures, 3 tables, MNRAS in press, minor corrections to match the published versio

Satellite content and quenching of star formation in galaxy groups at z ~ 1.8

We study the properties of satellites in the environment of massive star-forming galaxies at z ~ 1.8 in the COSMOS field, using a sample of 215 galaxies on the main sequence of star formation with an average mass of ~1011M⊙. At z> 1.5, these galaxies typically trace halos of mass ≳1013M⊙. We use optical-near-infrared photometry to estimate stellar masses and star formation rates (SFR) of centrals and satellites down to ~ 6 × 109M⊙. We stack data around 215 central galaxies to statistically detect their satellite halos, finding an average of ~3 galaxies in excess of the background density. We fit the radial profiles of satellites with simple β-models, and compare their integrated properties to model predictions. We find that the total stellar mass of satellites amounts to ~68% of the central galaxy, while spectral energy distribution modeling and far-infrared photometry consistently show their total SFR to be 25-35% of the central's rate. We also see significant variation in the specific SFR of satellites within the halo with, in particular, a sharp decrease at <100 kpc. After considering different potential explanations, we conclude that this is likely an environmental signature of the hot inner halo. This effect can be explained in the first order by a simple free-fall scenario, suggesting that these low-mass environments can shut down star formation in satellites on relatively short timescales of ~0.3 Gyr

The MRN complex is transcriptionally regulated by MYCN during neural cell proliferation to control replication stress

The MRE11/RAD50/NBS1 (MRN) complex is a major sensor of DNA double strand breaks, whose role in controlling faithful DNA replication and preventing replication stress is also emerging. Inactivation of the MRN complex invariably leads to developmental and/or degenerative neuronal defects, the pathogenesis of which still remains poorly understood. In particular, NBS1 gene mutations are associated with microcephaly and strongly impaired cerebellar development, both in humans and in the mouse model. These phenotypes strikingly overlap those induced by inactivation of MYCN, an essential promoter of the expansion of neuronal stem and progenitor cells, suggesting that MYCN and the MRN complex might be connected on a unique pathway essential for the safe expansion of neuronal cells. Here, we show that MYCN transcriptionally controls the expression of each component of the MRN complex. By genetic and pharmacological inhibition of the MRN complex in a MYCN overexpression model and in the more physiological context of the Hedgehog-dependent expansion of primary cerebellar granule progenitor cells, we also show that the MRN complex is required for MYCN-dependent proliferation. Indeed, its inhibition resulted in DNA damage, activation of a DNA damage response, and cell death in a MYCN- and replication-dependent manner. Our data indicate the MRN complex is essential to restrain MYCN-induced replication stress during neural cell proliferation and support the hypothesis that replication-born DNA damage is responsible for the neuronal defects associated with MRN dysfunctions.Cell Death and Differentiation advance online publication, 12 June 2015; doi:10.1038/cdd.2015.81