Association between weight gain and knee osteoarthritis: a systematic review.

OBJECTIVE: Although weight loss is recommended to manage knee osteoarthritis (KOA), adults tend to gain weight with age which may affect KOA symptoms and progression. We conducted a systematic review and data synthesis to investigate the association between weight gain and KOA, defined by clinical features, structural progression, and total knee replacement (TKR). DESIGN: MEDLINE and EMBASE were systematically searched for controlled trials and cohort studies of participants with (or at risk of) KOA examining the relationship between weight gain and KOA clinical features (pain, function, quality of life), structural progression, and TKR. Risk of bias was assessed using the ROBINS-I tool. Results were organised by outcome, with meta-analyses performed where appropriate. RESULTS: Twenty-three studies were included. Results showed significant detrimental effects of weight gain on pain (4 of 7 studies), stiffness (2 of 2 studies), function (5 of 6 studies), and the single studies examining quality of life, and clinical and radiographic KOA. Weight gain adversely affected cartilage (6 of 9 studies), bone marrow lesions (1 of 4 studies), meniscal damage (1 of 3 studies) and effusion/synovitis (1 of 1 study). Weight gain significantly increased TKR (3 of 6 studies): meta-analysis of 2 with available data demonstrated significant increases in TKR/5 kg weight gain in women, HR 1.34 (95% CI 1.18-1.51), and in men, HR 1.25 (95% CI 1.16-1.34). CONCLUSIONS: Weight gain in adults is associated with increased clinical and structural KOA and TKR. Prevention of weight gain should be considered to improve outcomes in KOA.

What is the evidence for interactions between filaggrin null mutations and environmental exposures in the aetiology of atopic dermatitis? A systematic review.

BACKGROUND: Epidemiological studies indicate that gene-environment interactions play a role in atopic dermatitis (AD). OBJECTIVES: To review the evidence for gene-environment interactions in AD aetiology, focusing on filaggrin (FLG) loss-of-function mutations. METHODS: A systematic search from inception to September 2018 in Embase, MEDLINE and BIOSIS was performed. Search terms included all synonyms for AD and filaggrin/FLG; any genetic or epidemiological study design using any statistical methods were included. Quality assessment using criteria modified from guidance (ROBINS-I and Human Genome Epidemiology Network) for nonrandomized and genetic studies was completed, including consideration of power. Heterogeneity of study design and analyses precluded the use of meta-analysis. RESULTS: Of 1817 papers identified, 12 studies fulfilled the inclusion criteria required and performed formal interaction testing. There was some evidence for FLG-environment interactions in six of the studies (P-value for interaction ≤ 0·05), including early-life cat ownership, older siblings, water hardness, phthalate exposure, higher urinary phthalate metabolite levels (which all increased AD risk additional to FLG null genotype) and prolonged breastfeeding (which decreased AD risk in the context of FLG null genotype). Major limitations of published studies were the low numbers of individuals (ranging from five to 94) with AD and FLG loss-of-function mutations and exposure to specific environmental factors, and variation in exposure definitions. CONCLUSIONS: Evidence on FLG-environment interactions in AD aetiology is limited. However, many of the studies lacked large enough sample sizes to assess these interactions fully. Further research is needed with larger sample sizes and clearly defined exposure assessment. Linked Comment: Park and Seo. Br J Dermatol 2020; 183:411.

CommWalker: correctly evaluating modules in molecular networks in light of annotation bias.

Motivation: Detecting novel functional modules in molecular networks is an important step in biological research. In the absence of gold standard functional modules, functional annotations are often used to verify whether detected modules/communities have biological meaning. However, as we show, the uneven distribution of functional annotations means that such evaluation methods favor communities of well-studied proteins. Results: We propose a novel framework for the evaluation of communities as functional modules. Our proposed framework, CommWalker, takes communities as inputs and evaluates them in their local network environment by performing short random walks. We test CommWalker's ability to overcome annotation bias using input communities from four community detection methods on two protein interaction networks. We find that modules accepted by CommWalker are similarly co-expressed as those accepted by current methods. Crucially, CommWalker performs well not only in well-annotated regions, but also in regions otherwise obscured by poor annotation. CommWalker community prioritization both faithfully captures well-validated communities and identifies functional modules that may correspond to more novel biology. Availability and implementation: The CommWalker algorithm is freely available at opig.stats.ox.ac.uk/resources or as a docker image on the Docker Hub at hub.docker.com/r/lueckenmd/commwalker/. Contact: deane@stats.ox.ac.uk. Supplementary information: Supplementary data are available at Bioinformatics online.

The rapid assembly of an elliptical galaxy of 400 billion solar masses at a redshift of 2.3.

Stellar archaeology shows that massive elliptical galaxies formed rapidly about ten billion years ago with star-formation rates of above several hundred solar masses per year. Their progenitors are probably the submillimetre bright galaxies at redshifts z greater than 2. Although the mean molecular gas mass (5 × 10(10) solar masses) of the submillimetre bright galaxies can explain the formation of typical elliptical galaxies, it is inadequate to form elliptical galaxies that already have stellar masses above 2 × 10(11) solar masses at z ≈ 2. Here we report multi-wavelength high-resolution observations of a rare merger of two massive submillimetre bright galaxies at z = 2.3. The system is seen to be forming stars at a rate of 2,000 solar masses per year. The star-formation efficiency is an order of magnitude greater than that of normal galaxies, so the gas reservoir will be exhausted and star formation will be quenched in only around 200 million years. At a projected separation of 19 kiloparsecs, the two massive starbursts are about to merge and form a passive elliptical galaxy with a stellar mass of about 4 × 10(11) solar masses. We conclude that gas-rich major galaxy mergers with intense star formation can form the most massive elliptical galaxies by z ≈ 1.5.

The suppression of star formation by powerful active galactic nuclei.

The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight correlation between the mass of the black hole and the mass of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming galaxies are usually dust-obscured and are brightest at infrared and submillimetre wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expelling the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.

Submillimetre galaxies reside in dark matter haloes with masses greater than 3 × 10(11) solar masses.

The extragalactic background light at far-infrared wavelengths comes from optically faint, dusty, star-forming galaxies in the Universe with star formation rates of a few hundred solar masses per year. These faint, submillimetre galaxies are challenging to study individually because of the relatively poor spatial resolution of far-infrared telescopes. Instead, their average properties can be studied using statistics such as the angular power spectrum of the background intensity variations. A previous attempt at measuring this power spectrum resulted in the suggestion that the clustering amplitude is below the level computed with a simple ansatz based on a halo model. Here we report excess clustering over the linear prediction at arcminute angular scales in the power spectrum of brightness fluctuations at 250, 350 and 500 µm. From this excess, we find that submillimetre galaxies are located in dark matter haloes with a minimum mass, M(min), such that log(10)[M(min)/M(⊙)] = 11.5(+0.7)(-0.2) at 350 µm, where M(⊙) is the solar mass. This minimum dark matter halo mass corresponds to the most efficient mass scale for star formation in the Universe, and is lower than that predicted by semi-analytical models for galaxy formation.

An extremely luminous X-ray outburst at the birth of a supernova.

Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the 'break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.

Submillimeter evidence for the coeval growth of massive black holes and galaxy bulges.

The correlation, found in nearby galaxies, between black hole mass and stellar bulge mass implies that the formation of these two components must be related. Here we report submillimeter photometry of eight x-ray-absorbed active galactic nuclei that have luminosities and redshifts characteristic of the sources that produce the bulk of the accretion luminosity in the universe. The four sources with the highest redshifts are detected at 850 micrometers, with flux densities between 5.9 and 10.1 millijanskies, and hence are ultraluminous infrared galaxies. If the emission is from dust heated by starbursts, then the majority of stars in spheroids were formed at the same time as their central black holes built up most of their mass by accretion. This would account for the observed demography of massive black holes in the local universe. The skewed rate of submillimeter detection with redshift is consistent with a high redshift epoch of star formation in radio-quiet active galactic nuclei, similar to that seen in radio galaxies.

Serum regulation of the estrogen responsiveness of the human breast cancer cell line MCF-7.

Initially after receiving MCF-7 cells, we were able to confirm their estrogen responsiveness. We observed significant increases in thymidine incorporation, in thymidine kinase activity, and in cell numbers in response to 10(-8) M estradiol. Subsequently, however, the cells failed to show a response to estradiol. A growth response to estradiol could be restored by increasing the serum concentration in the medium. Cells grown in 15% serum (calf or human) responded to estradiol with increased rates of growth and thymidine incorporation and increased activities of thymidine kinase and DNA polymerase. We suggest that there is present in serum a "factor" which can influence the expression of a growth response to estradiol.

A novel, orally administered nucleoside analogue, OGT 719, inhibits the liver invasive growth of a human colorectal tumor, C170HM2.

OGT 719 is a novel p.o. bioavailable nucleoside analogue in which galactose is incorporated onto the fluoropyrimidine moiety of the cytotoxic agent 5-fluorouracil (5-FU). OGT 719 has been designed to reduce the systemic toxicity normally associated with 5-FU while retaining activity against disease localized in the liver, in which it may be preferentially localized through the asialoglycoprotein receptor (ASGP-R). We report studies confirming the activity of OGT 719 in inhibiting growth of metastatic human colorectal tumors in the liver of nude mice. The human colorectal cancer cell line C170HM2 readily forms liver metastases in vivo. Oral administration of 1500 mg/kg/day OGT 719 inhibited liver tumor burden by 95% compared with vehicle control, without any observable signs of toxicity. When the tumor burden was increased and the same OGT 719 treatment was compared with a standard clinical dose regimen of 25 mg/kg/day 5-FU/leucovorin given i.v., both treatments were equally efficacious, although 5-FU/leucovorin treatment started 7 days earlier. In contrast to 5-FU, OGT 719 is p.o. bioavailable and has a plasma half-life between 1.5 and 3 h. Several colorectal cancer cell lines express the asialoglycoprotein receptor, although no significant levels can be detected in C170HM2 cells, consistent with the observation that OGT 719 is approximately 3 log orders of magnitude less potent in vitro than 5-FU. Flux through thymidylate synthase, as measured by 3H release from [3H]dUrd, was inhibited by OGT 719 at 4 h. The notable difference in the potency of OGT 719 efficacy on C170HM2 cells in vitro and in vivo supports our model of liver-specific activation of OGT 719. As our data suggest, OGT 719 may significantly inhibit growth of metastatic colorectal tumors in the liver in vivo. This hypothesis is presently being explored in clinical trials for primary hepatocellular carcinoma and colorectal liver metastases.

The Ha-ras protein, p21, is modified by a derivative of mevalonate and methyl-esterified when expressed in the insect/baculovirus system.

Using the insect/baculovirus expression system, we demonstrate the incorporation of [3H]mevalonate and [3H]methyl groups into recombinant c-Ha-ras protein (p21). Unlike the post-translational palmitoylation of p21 expressed in this system, the modification by mevalonate is not removed by hydroxylamine suggesting the absence of a thioester linkage. It is highly likely that the insect expression system recognizes the C-terminal CAAX Motif in p21, incorporates the mevalonate into the recently described polyisoprenylation modification and carboxyl-methylates the protein.

Cloning and characterisation of cDNAs encoding a novel non-receptor tyrosine kinase, brk, expressed in human breast tumours.

Using a polymerase chain reaction based differential screening approach, we have isolated and characterised a cDNA from a human metastatic breast tumour representing a novel protein tyrosine kinase (brk). Sequencing of brk cDNAs isolated from T-47D and MCF-7 human breast tumour cell lines indicate that they encode a protein with the features of a novel nonreceptor tyrosine kinase, including amino terminal SH3 and SH2 domains. When synthesised in recombinant baculovirus and bacterial expression systems, brk protein products are capable of autophosphorylation on tyrosine residues. Initial expression studies have detected low levels of brk transcripts in some human breast tumours and breast tumour cell lines, but not in normal breast tissue.

Expression patterns of the novel receptor-like tyrosine kinase, DDR, in human breast tumours.

Using a reverse transcriptase-polymerase chain reaction based differential screening procedure, we have identified the discoidin domain receptor as a protein tyrosine kinase that is expressed in lymph nodes containing breast tumour metastases. By Northern blotting and in situ hybridisation we have demonstrated the expression of the discoidin domain receptor in human primary breast tumour samples, metastasis-containing lymph nodes and a number of normal tissues. Direct comparison of malignant breast and adjacent normal epithelial tissue revealed over expression in the tumour cells.

Comparison of baculovirus-expressed c-Abl and BCR/ABL protein tyrosine kinases.

Mouse c-Abl type IV and human BCR/ABL proteins have been expressed in insect cells using the baculovirus system. The proteins were expressed as full-length polypeptides as judged by electrophoresis in denaturing gels. They were identified by immunoprecipitation and immunoblotting with antibodies against ABL peptides and, for BCR/ABL, against a BCR peptide. In these immunoprecipitates both proteins gave autophosphorylation principally on tyrosine. Both proteins were active tyrosine kinases, phosphorylating a variety of tyrosine-containing substrates. In fresh extracts both proteins contained phosphotyrosine as shown by Western blots with antiphosphotyrosine antibodies. Partial purification could be achieved readily using ion exchange columns, and the BCR/ABL protein, p210BCR/ABL, could be further purified to near-homogeneity using an antiphosphotyrosine column. Both enzymes required a divalent metal ion for activity. At low concentrations of ATP (2 microM) and with angiotensin II as substrate both enzymes were activated by Mn2+ or by Mg2+. No major differences in catalytic properties were found between the two isolated enzymes in solution. The oncogenic properties of p210BCR/ABL may be due to its different subcellular location, or to the presence of an intracellular inhibitor of c-Abl that does not inhibit BCR/ABL, or to altered substrate-specificity such that it can phosphorylate a unique substrate which is not recognised by c-Abl.

Expression of the mouse c-abl type IV proto-oncogene product in the insect cell baculovirus system.

The cellular gene c-abl is the normal homologue of the transforming gene (v-abl) within the genome of the Abelson leukaemia virus. The cDNA sequence coding for the cellular form of the murine abl gene (c-abl type IV) has been inserted into the baculovirus transfer vector, pAc36C, so that the c-abl gene is under the control of the polyhedrin promoter of Autographa californica nuclear polyhedrosis virus (AcNPV). Spodoptera frugiperda cells infected with the recombinant transfer vector in the presence of wild type AcNPV DNA yielded recombinant, polyhedrin negative virus that expressed moderate levels of the c-Abl protein (representing approx. 0.5-1% of the stained cellular proteins as determined by densitometric scanning). The insect derived c-Abl protein was compared to the P210-BCR/ABL protein from K562 cells, a cell line derived from a patient with chronic myelogenous leukaemia. Antibodies raised against synthetic peptides based on c-abl encoded peptides react with the insect derived c-Abl. In addition, the baculovirus derived c-Abl protein has a tyrosine kinase activity as demonstrated by phosphorylation of a synthetic polypeptide and also by autophosphorylation. Phosphoamino acid analysis of immunoprecipitated, autophosphorylated baculovirus derived c-Abl protein indicates that the majority of label incorporated is on the tyrosine residues. Immunofluorescence microscopy has been used to show that the majority of the c-Abl protein expressed in cells infected with recombinant virus is located in the nuclear and plasma membranes.

Determinants of specificity in coagulation proteases.

Proteases play diverse roles in a variety of essential biological processes, both as non-specific catalysts of protein degradation and as highly specific agents that control physiologic events. Here, we review the mechanisms of substrate specificity employed by serine proteases and focus our discussion on coagulation proteases. We dissect the interplay between active site and exosite specificity and how substrate recognition is regulated allosterically by Na+ binding. We also draw attention to a functional polarity that exists in the serine protease fold, which sheds light on the structural linkages between the active site and exosites.

Expression of amplified human beta interferon genes using heavy metal induction in Chinese hamster ovary cells.

An expression cassette consisting of the human beta-interferon (beta-IFN) cDNA fused to the human metallothionein (MeT)IIA promoter has been linked to a selectable mouse dihydrofolate reductase gene (dhfr) and used to transform dhfr-deficient Chinese hamster ovary (CHO) cells. Transformants resistant to increasing concentrations of methotrexate (Mtx) were isolated and found to secrete beta-IFN either constitutively or upon induction with cadmium (up to 325 000 units beta-IFN/10(6) cells/24 h). Molecular analysis demonstrates a large increase in beta-IFN-specific DNA sequences and beta-IFN mRNA levels in amplified cell lines, with initiation of transcription occurring at the authentic start point for the MeT promoter.

A new retroviral vector, CA1, to identify and select for cells expressing an inserted gene in vitro and in vivo.

A new retroviral vector has been constructed that expresses genes encoding three different activities from a single transcript. This feature has been exploited to enable the efficient marking and selection of cells that express a gene of interest. The marker gene lacZ, encoding beta-galactosidase, and neo, encoding neomycin phosphotransferase, for selection by the antibiotic G418, are expressed as a fusion, beta Geo. The expression of beta Geo is coordinated with expression of a gene of interest at the mRNA level using an Internal Ribosome Entry Site (IRES) from the Encephalomyocarditis Virus (EMCV). The IRES promotes cap-independent initiation of translation therefore two reading frames can be translated from a single transcript. In vitro, the vector has been shown to confer beta-galactosidase activity, transformation by v-src and resistance to G418, following infection of cells. To show that the retrovirus was able to mark infected cells in vivo, cells infected with the retrovirus were transplanted into mouse mammary gland where they grew and were successfully located by staining for beta-galactosidase over 2 months after transplantation.

Functional properties of human thyroid hormone receptor beta 1 overexpressed using baculovirus.

We have overexpressed the human beta 1 thyroid hormone receptor in insect cells using a recombinant baculovirus to a level of 5-10% of total cellular protein. The recombinant protein migrates as a 50 kDa band by SDS-PAGE and Western blot analysis. The expressed receptor binds to L-T3 with a Kd of 1.3 +/- 0.4 x 10(-10) M and to thyroid hormone analogues with an affinity hierarchy of TRIAC greater than L-T3 greater than L-T4 greater than rT3. Gel retardation assays show highly specific receptor binding to a TRE which is modified by the presence of ligand and avidin-biotin complex DNA analysis shows a Kd of 6.2 +/- 2.0 x 10(-10) M for this interaction. These results indicate high level expression of hTR beta with authentic hormone and DNA binding properties.

Molecular cloning of a human thyrotropin receptor cDNA fragment. Use of highly degenerate, inosine containing primers derived from aligned amino acid sequences of a homologous family of glycoprotein hormone receptors.

Autoantibodies to the thyrotropin (TSH) hormone receptor (TSH-R) are present in the sera of patients with thyroid autoimmune disease which are pathogenetic leading to hyperthyroidism of Graves' disease. Considerable interest has been focused on the cloning of the human TSH-R, which has until very recently, proven exceedingly difficult due to the very low receptor level expression on thyroid cells. We have used polymerase chain reaction and highly degenerate, inosine containing oligonucleotides derived from sequence alignments of the transmembrane regions 2 and 7 of a number of G-binding protein receptors including the lutropin/choriogonadotropin (LH/CG) receptors to amplify various cDNAs from human thyroid cDNA. Sequencing analysis of 27 different clones revealed that they fall into eight different groups. The very recent publication of the complete nucleotide sequence of the human TSH-R revealed that one of the groups (GT1) containing seven clones which had been sequenced belong to the human TSH-receptor. The sequence of all 7 GT1 clones was identical and in complete concordance with transmembrane regions 2 and 7 of the published TSH-R sequence. Our results show that by designing oligonucleotides to common transmembrane regions of G-binding proteins where the primers are biased in their sequence to the LH/CG receptors it is possible to amplify the TSH-R receptor sequence.