Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

A new prognostic classification of chronic lymphocytic leukemia derived from a multivariate survival analysis

Survivals of two series of CLL patients (99 from a retrospective series and 196 from a prospective series) were studied separately. The three main staging systems (Rai, Binet, Rundles) agreed well, but as far as survival is concerned, too many stages are defined. The authors performed a Cox multivariate analysis of survival in order to isolate important prognostic factors at diagnosis and to use them to build a simple three-stage classification. Thrombopenia and anemia appeared as the most important risk factors. Among the nonanemic and nonthrombopenic patients, the number of involved areas was clearly related to prognosis in the authors' two series. This study allowed the authors to propose a new classification in three prognostic groups. Group C: anemia (Hb less than 10 g) and/or thrombopenia (platelets less than 100,000/mm3); about 15% of the patients; median of 2 years. Group B: no anemia, no thrombopenia, three or more involved areas (counting as one each of the following: axillary, cervical, inguinal, lymph nodes, whether unilateral or bilateral, spleen and liver); about 30% of patients; median of 7 years. Group A: no anemia, no thrombopenia, less than three involved areas; about 55% of patients; the survival of this group does not seem different from that of the French population of the same age and sex distribution. This three-stage classification only requires clinical examination and routine hemogram, has a good prognostic value which was confirmed on the series of Montserrat and Rozman (146 patients), and should therefore be helpful in planning new clinical trials.

GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral

On August 17, 2017 at 12∶41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0×10^{4}  years. We infer the component masses of the binary to be between 0.86 and 2.26  M_{⊙}, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60  M_{⊙}, with the total mass of the system 2.74_{-0.01}^{+0.04}M_{⊙}. The source was localized within a sky region of 28  deg^{2} (90% probability) and had a luminosity distance of 40_{-14}^{+8}  Mpc, the closest and most precisely localized gravitational-wave signal yet. The association with the γ-ray burst GRB 170817A, detected by Fermi-GBM 1.7 s after the coalescence, corroborates the hypothesis of a neutron star merger and provides the first direct evidence of a link between these mergers and short γ-ray bursts. Subsequent identification of transient counterparts across the electromagnetic spectrum in the same location further supports the interpretation of this event as a neutron star merger. This unprecedented joint gravitational and electromagnetic observation provides insight into astrophysics, dense matter, gravitation, and cosmology.

Myostatin, a negative regulator of muscle growth, functions by inhibiting myoblast proliferation

Myostatin, a member of the transforming growth factor-beta (TGF-beta) superfamily, has been shown to be a negative regulator of myogenesis. Here we show that myostatin functions by controlling the proliferation of muscle precursor cells. When C(2)C(12) myoblasts were incubated with myostatin, proliferation of myoblasts decreased with increasing levels of myostatin. Fluorescence-activated cell sorting analysis revealed that myostatin prevented the progression of myoblasts from the G(1)- to S-phase of the cell cycle. Western analysis indicated that myostatin specifically up-regulated p21(Waf1, Cip1), a cyclin-dependent kinase inhibitor, and decreased the levels and activity of Cdk2 protein in myoblasts. Furthermore, we also observed that in myoblasts treated with myostatin protein, Rb was predominately present in the hypophosphorylated form. These results suggests that, in response to myostatin signaling, there is an increase in p21 expression and a decrease in Cdk2 protein and activity thus resulting in an accumulation of hypophosphorylated Rb protein. This, in turn, leads to the arrest of myoblasts in G(1)-phase of cell cycle. Thus, we propose that the generalized muscular hyperplasia phenotype observed in animals that lack functional myostatin could be as a result of deregulated myoblast proliferation.

Neural basis of alertness and cognitive performance impairments during sleepiness. I. Effects of 24 h of sleep deprivation on waking human regional brain activity

The negative effects of sleep deprivation on alertness and cognitive performance suggest decreases in brain activity and function, primarily in the thalamus, a subcortical structure involved in alertness and attention, and in the prefrontal cortex, a region subserving alertness, attention, and higher-order cognitive processes. To test this hypothesis, 17 normal subjects were scanned for quantifiable brain activity changes during 85 h of sleep deprivation using positron emission tomography (PET) and (18)Fluorine-2-deoxyglucose ((18)FDG), a marker for regional cerebral metabolic rate for glucose (CMRglu) and neuronal synaptic activity. Subjects were scanned prior to and at 24-h intervals during the sleep deprivation period, for a total of four scans per subject. During each 30 min (18)FDG uptake, subjects performed a sleep deprivation-sensitive Serial Addition/Subtraction task. Polysomnographic monitoring confirmed that subjects were awake. Twenty-four hours of sleep deprivation, reported here, resulted in a significant decrease in global CMRglu, and significant decreases in absolute regional CMRglu in several cortical and subcortical structures. No areas of the brain evidenced a significant increase in absolute regional CMRglu. Significant decreases in relative regional CMRglu, reflecting regional brain reductions greater than the global decrease, occurred predominantly in the thalamus and prefrontal and posterior parietal cortices. Alertness and cognitive performance declined in association with these brain deactivations. This study provides evidence that short-term sleep deprivation produces global decreases in brain activity, with larger reductions in activity in the distributed cortico-thalamic network mediating attention and higher-order cognitive processes, and is complementary to studies demonstrating deactivation of these cortical regions during NREM and REM sleep.

Role of a p53 polymorphism in the development of human papillomavirus-associated cancer

The E6 oncoprotein derived from tumour-associated human papillomaviruses (HPVs) binds to and induces the degradation of the cellular tumour-suppressor protein p53. A common polymorphism that occurs in the p53 amino-acid sequence results in the presence of either a proline or an arginine at position 72. The effect of this polymorphism on the susceptibility of p53 to E6-mediated degradation has been investigated and the arginine form of p53 was found to be significantly more susceptible than the proline form. Moreover, allelic analysis of patients with HPV-associated tumours revealed a striking overrepresentation of homozygous arginine-72 p53 compared with the normal population, which indicated that individuals homozygous for arginine 72 are about seven times more susceptible to HPV-associated tumorigenesis than heterozygotes. The arginine-encoding allele therefore represents a significant risk factor in the development of HPV-associated cancers.

Mutations at the murine motheaten locus are within the hematopoietic cell protein-tyrosine phosphatase (Hcph) gene

Mice homozygous for the recessive allelic mutation motheaten (me) or viable motheaten (mev) on chromosome 6 develop severe defects in hematopoiesis. In this paper we present the findings that the me and mev mutations are within the hematopoietic cell protein-tyrosine phosphatase (Hcph) gene. High resolution mapping localized me to an area tightly linked to Hcph on chromosome 6. Abnormalities of the Hcph protein product were demonstrated by Western blot analysis and by activity assays in both me/me and mev/mev mice. Molecular analysis of the Hcph cDNA identified abnormal transcripts in both mutants. DNA sequence analyses of cDNA and genomic clones revealed that both the me and mev mutations are point mutations that result in aberrant splicing of the Hcph transcript. These findings provide the first available animal models for a specific protein-tyrosine phosphatase deficiency, thus facilitating determination of the precise role of this signaling molecule in hematopoiesis.

CD45: an emerging role as a protein tyrosine phosphatase required for lymphocyte activation and development

CD45 is one of the most abundant leukocyte cell surface glycoproteins and is expressed exclusively upon cells of the hematopoietic system. Different isoforms of CD45 are generated by alternative splicing and are expressed in cell type-specific patterns on functional subpopulations of lymphocytes. In a major advance, CD45 was identified as one of the first members of a novel class of enzymes, the protein tyrosine phosphatases (PTPs). This serendipitous discovery linked CD45 to the process of reversible protein tyrosine phosphorylation, a key regulatory mechanism for controlling the growth and division of eukaryotic cells, and provided the impetus for most of the studies described in this review. CD45 is now established as a critical component of the signal transduction machinery of lymphocytes. In particular, evidence from genetic experiments indicates that CD45 plays a pivotal role in antigen-stimulated proliferation of T lymphocytes and in thymic development. Two members of the Src-family of protein tyrosine kinases (PTKs), the p56lck and p59fyn proteins, have been implicated as physiological substrates of CD45, providing an important clue to how the action of this leukocyte-specific PTP might influence signaling by the T cell antigen receptor. Structure-function analysis of CD45 and other PTPs has identified structural features of PTP catalytic domains required for enzymatic activity. However, despite intensive efforts, little is known about how the activity of CD45 is regulated. The external domain of CD45 does not appear to be absolutely required for signal transduction by the T cell receptor, and there is currently no evidence that ligand binding modulates CD45 activity. Analysis of CD45 isoform expression has revealed a hitherto unrecognized plasticity in isoform usage by T cells and other leukocytes, adding to the regulatory complexity of isoform expression.

Prospective study of the impact of fear of falling on activities of daily living, SF-36 scores, and nursing home admission

BACKGROUND

The aim of this study was to assess the impact of fear of falling on the health of older people.

METHODS

A total of 528 subjects (mean age 77 years) were recruited from two hospitals in Sydney, Australia, and followed for approximately 12 months. Eighty-five subjects died during follow-up, and 31 were admitted to an aged care institution. Tinetti's Falls Efficacy Scale (FES) was successfully administered to 418 subjects as part of the baseline assessment. Among those with baseline FES scores, ability to perform 10 activities of daily living (ADLs) was assessed at baseline and follow-up in 307 subjects, and SF-36 scores were assessed at baseline and follow-up in 90 subjects recruited during the latter part of the study. Falls during follow-up were identified using a monthly falls calendar.

RESULTS

Compared with those with a high fall-related self-efficacy (FES score = 100), those with a low fall-related self-efficacy (FES score < or = 75) had an increased risk of falling (adjusted relative risk 2.09, 95% confidence interval [CI] 1.31-3.33). Those with poorer fall-related self-efficacy had greater declines in ability to perform ADLs (p < .001): the total ADL score decreased by 0.69 activities among persons with low FES scores (< or =75) but decreased by only 0.04 activities among persons with FES scores of 100. Decline in ADLs was not explained by the higher frequency of falls among persons with low FES scores. SF-36 scores (particularly scores on the Physical Function and Bodily Pain subscales) tended to decline more among persons with poor fall-related self-efficacy. Nonfallers who said they were afraid of falling had an increased risk of admission to an aged care institution.

CONCLUSIONS

Fear of falling has serious consequences for older people. Interventions that successfully reduce fear of falling and improve fall-related self-efficacy are likely to have major health benefits.

Different intensities of oral anticoagulant therapy in the treatment of proximal-vein thrombosis

We have previously reported that long-term therapy with warfarin is effective for preventing recurrent venous thromboembolism in patients with proximal-vein thrombosis but that there is an appreciable risk of hemorrhage. To determine whether that risk could be reduced without a loss of effectiveness, we randomly allocated 96 patients with proximal-vein thrombosis to a group receiving less intense anticoagulant therapy, with a mean prothrombin time of 26.9 seconds using the Manchester comparative reagent (corresponding Simplastin time, 15 seconds), or a group given more intense therapy, with a mean Simplastin time of 19.4 seconds (corresponding prothrombin time 41 seconds with the Manchester comparative reagent) (P less than 0.001). Two of 47 patients (4 per cent) in the less intensely treated group had hemorrhagic complications, as compared with 11 of 49 patients (22 per cent) in the more intensely anticoagulated group (P = 0.015 by the two-tailed test). This difference was due to minor bleeding episodes. The frequency of recurrent venous thromboembolism was low in both groups (2 per cent). Our findings indicate that less intense anticoagulant therapy is associated with a low frequency of recurrent venous thromboembolism (2 per cent) and a reduced risk of hemorrhage.

The association of atopy with a gain-of-function mutation in the alpha subunit of the interleukin-4 receptor

BACKGROUND

Atopic diseases are very common, and atopy has a strong genetic predisposition.

METHODS

Using single-strand conformation polymorphism analysis and DNA sequencing, we searched for mutations in the a subunit of the interleukin-4 receptor that would predispose persons to atopy. We examined the prevalence of the alleles among patients with allergic inflammatory disorders and among 50 prospectively recruited adults. Subjects with atopy were identified on the basis of an elevated serum IgE level (> or = 95 IU per milliliter) or a positive radioimmunosorbent test in response to standard inhalant allergens. The signaling function of mutant interleukin-4 receptor a was examined by flow cytometry, binding assays, and immunoblotting.

RESULTS

A novel interleukin-4 receptor alpha allele was identified in which guanine was substituted for adenine at nucleotide 1902, causing a change from glutamine to arginine at position 576 (R576) in the cytoplasmic domain of the interleukin-4 receptor alpha protein. The R576 allele was common among patients with allergic inflammatory disorders (found in 3 of 3 patients with the hyper-IgE syndrome and 4 of 7 patients with severe atopic dermatitis) and among the 50 prospectively recruited adults (found in 13 of 20 subjects with atopy and 5 of 30 without atopy; P=0.001; relative risk of atopy among those with a mutant allele, 9.3). The R576 allele was associated with higher levels of expression of CD23 by interleukin-4 than the wild-type allele. This enhanced signaling was associated with a change in the binding specificity of the adjacent tyrosine residue at position 575 to signal-transducing molecules.

CONCLUSIONS

The R576 allele of interleukin-4 receptor alpha is strongly associated with atopy. This mutation may predispose persons to allergic diseases by altering the signaling function of the receptor.

Two polymorphic variants of wild-type p53 differ biochemically and biologically

The wild-type p53 protein exhibits a common polymorphism at amino acid 72, resulting in either a proline residue (p53Pro) or an arginine residue (p53Arg) at this position. Despite the difference that this change makes in the primary structure of the protein resulting in a difference in migration during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, no differences in the biochemical or biological characteristics of these wild-type p53 variants have been reported. We have recently shown that p53Arg is significantly more susceptible than p53Pro to the degradation induced by human papillomavirus (HPV) E6 protein. Moreover, this may result in an increased susceptibility to HPV-induced tumors in homozygous p53Arg individuals. In further investigating the characteristics of these p53 variants, we now show that both forms are morphologically wild type and do not differ in their ability to bind to DNA in a sequence-specific manner. However, there are a number of differences between the p53 variants in their abilities to bind components of the transcriptional machinery, to activate transcription, to induce apoptosis, and to repress the transformation of primary cells. These observations may have implications for the development of cancers which harbor wild-type p53 sequences and possibly for the ability of such tumors to respond to therapy, depending on their p53 genotype.

A role in B cell activation for CD22 and the protein tyrosine phosphatase SHP

CD22 is a membrane immunoglobulin (mIg)-associated protein of B cells. CD22 is tyrosine-phosphorylated when mIg is ligated. Tyrosine-phosphorylated CD22 binds and activates SHP, a protein tyrosine phosphatase known to negatively regulate signaling through mIg. Ligation of CD22 to prevent its coaggregation with mIg lowers the threshold at which mIg activates the B cell by a factor of 100. In secondary lymphoid organs, CD22 may be sequestered away from mIg through interactions with counterreceptors on T cells. Thus, CD22 is a molecular switch for SHP that may bias mIg signaling to anatomic sites rich in T cells.

Evidence that the leukocyte-common antigen is required for antigen-induced T lymphocyte proliferation

The leukocyte-common antigen (L-CA) is a family of large molecular weight glycoproteins uniquely expressed on the surface of all nucleated cells of hematopoietic origin. The glycoprotein consists of a heavily glycosylated exterior domain, a single membrane spanning region, and a large cytoplasmic domain that contains tyrosine phosphatase activity. To investigate the function of this family, we generated T cell clones that lacked L-CA (L-CA-). The expression of the alpha beta T cell receptor, CD3, CD4, IL-2 receptor (p55), LFA-1, Thy-1, and Pgp-1 (CD44) was normal. The L-CA- T cell clones failed to proliferate in response to antigen or cross-linked CD3; however, they could still proliferate in response to IL-2. An L-CA+ revertant was obtained and the ability to proliferate in response to antigen and cross-linked CD3 was restored. These data indicate that L-CA is required for T cells to enter into cell cycle in response to antigen.

GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence

We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4_{-0.9}^{+0.7}×10^{-22}. The inferred source-frame initial black hole masses are 14.2_{-3.7}^{+8.3}M_{⊙} and 7.5_{-2.3}^{+2.3}M_{⊙}, and the final black hole mass is 20.8_{-1.7}^{+6.1}M_{⊙}. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440_{-190}^{+180}  Mpc corresponding to a redshift of 0.09_{-0.04}^{+0.03}. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.

Normal B lymphocyte development but impaired T cell maturation in CD45-exon6 protein tyrosine phosphatase-deficient mice

The transmembrane tyrosine phosphatase CD45 is expressed in multiple isoforms on all nucleated hematopoietic cells, resulting from alternative splicing of variable exons. We generated mice with a mutation in the variable CD45 exon 6, using homologous recombination. In mice homozygous for the CD45-exon6 mutation, B cells and most T cells did not express CD45. Development of B cells appeared normal, although Ig mu-induced proliferation was completely abrogated. Thymocyte maturation was blocked at the transitional stage from immature CD4+CD8+ to mature CD4+ or CD8+ cells, and only a few T cells could be detected in peripheral lymphoid organs. Clonal deletion of superantigen-reactive T cells still occurred. Cytotoxic T cell responses to lymphocytic choriomeningitis virus were absent in CD45-exon6-/- mice. These data imply that CD45 is differentially required for the development and function of B and T lymphocytes.

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Tyrosine phosphatase CD45 is essential for coupling T-cell antigen receptor to the phosphatidyl inositol pathway

Stimulation of T lymphocytes through their antigen receptor (T-cell receptor; TCR) results in the activation of a tyrosine kinase and the generation of phosphatidyl inositol (PtdIns)-derived second messengers. Several reports have indicated that CD45, a haematopoietic cell-specific surface glycoprotein with tyrosine phosphatase activity in its cytoplasmic domain, is important in lymphocyte activation. To examine the possibility that CD45 might influence proximal signal transduction events through the TCR, we have isolated a variant of the human T-cell leukaemic line, HPB-ALL, which fails to express this phosphatase. Unlike cells expressing CD45, stimulation of the TCR in the CD45-negative cell does not result in PtdIns-derived second messengers. Reconstitution of CD45 expression restored early signalling events through the TCR. To localize the site of CD45 action, the human muscarinic type 1 receptor, which also activates the PtdIns second messenger pathway, was transfected into the CD45-negative cell. Although stimulation of the TCR failed to generate PtdIns-derived second messengers, there was normal activity of the PtdIns pathway when human muscarinic receptor type 1 was stimulated, despite the absence of CD45. These data indicate that CD45 influences a cellular component that is essential for effective coupling of the TCR to the PtdIns second messenger pathway.

Non-viral gene therapy: polycation-mediated DNA delivery

Gene therapy, i.e., the expression in cells of genetic material with therapeutic activity, holds great promise for the treatment of human diseases. A delivery vehicle (vector), of either viral or non-viral origin, must be used to carry the foreign gene into a cell. Viral vectors take advantage of the facile integration of the gene of interest into the host and high probability of its long-term expression but are plagued by safety concerns. Non-viral vectors, although less efficient at introducing and maintaining foreign gene expression, have the profound advantage of being non-pathogenic and non-immunogenic; they are the subject of this review. Polycation-DNA complexes are particularly attractive for non-viral gene therapy. To perform, they have to attach to the target cell surface, be internalized, escape from endosomes, find a way to the nucleus, and, finally, be available for transcription. The clinical usefulness of polycationic vectors depends on elucidating the role each of these steps plays in gene transfer. Recent progress in consequent rational vector improvement is highlighted by our finding of polyethylenimine derivatives more potent and yet less cytotoxic than the 25-kDa polyethylenimine (one of the most effective non-viral vectors). Such vectors could be further modified with cell-targeting ligands to enhance their utility for in vivo applications.

Different nuclear signals are activated by the B cell receptor during positive versus negative signaling

It is not known how immunogenic versus tolerogenic cellular responses are signaled by receptors such as the B cell antigen receptor (BCR). Here we compare BCR signaling in naive cells that respond positively to foreign antigen and self-tolerant cells that respond negatively to self-antigen. In naive cells, foreign antigen triggered a large biphasic calcium response and activated nuclear signals through NF-AT, NF-kappa B, JNK, and ERK/pp90rsk. In tolerant B cells, self-antigen stimulated low calcium oscillations and activated NF-AT and ERK/pp90rsk but not NF-kappa B or JNK. Self-reactive B cells lacking the phosphatase CD45 did not exhibit calcium oscillations or ERK/pp90rsk activation, nor did they repond negatively to self-antigen. These data reveal striking biochemical differences in BCR signaling to the nucleus during positive selection by foreign antigens and negative selection by self-antigens.

The role of the E6-p53 interaction in the molecular pathogenesis of HPV

Human papillomaviruses (HPVs) are associated with a number of clinical conditions, of which the most serious is cervical carcinoma. The E6 protein of the oncogenic, mucosal-specific HPV types has been shown to complex with p53 and, as a result, target it for rapid proteasome-mediated degradation. As a consequence, p53's growth-arrest and apoptosis-inducing activities are abrogated. Since p53 is frequently wild type in cervical cancers, unlike other cancers in which it is often mutated, the notion has arisen that E6's activity with respect to p53 is equivalent to an inactivating mutation of p53. In addition, several studies have shown that the pathways both upstream and downstream of p53 are intact in cervical cancers; this suggests the potential importance of the E6 - p53 interaction for therapeutic intervention. However, like all viral oncoproteins, E6 is a multifunctional protein and a plethora of other cellular targets has been identified. Indeed, E6's interactions with some of these additional targets appear to be equally important in the pathogenesis of HPV, and may also represent valid targets for therapeutic intervention.