173 research outputs found
Evaluation and recommendations of the oral health, oral function, and orofacial aesthetics-related measures of the ICHOM Standard Set for Cleft Lip and Palate
This study was performed to evaluate the efficacy of outcome measures for the orofacial domain included in the International Consortium for Health Outcomes Measurement Standard Set for Cleft Lip and Palate (ICHOM-SCS). In this multicentre study involving two cleft centres, suggestions to optimize the type and timing of outcome measures were made based on data and clinical experience. Patient-reported outcome measures (PROMs) (CLEFT-Q Jaw, Teeth, Eating/Drinking; Child Oral Health Impact Profile—Oral Symptoms Scale (COHIP-OSS)) and clinical outcome measures (caries experience and dental occlusion) data were collected retrospectively for age 5, 8, 10, 12, 19, and 22 years. The data were categorized by cleft type and analysed within and between age groups using Spearman correlation, the distribution of responses per item, a two-sample test for equality of proportions, and effect plots. Most correlations between PROMs and clinical outcome measures were weak (r < 0.5), suggesting PROMs and clinical outcome measures complement each other. The COHIP-OSS and CLEFT-Q Eating/Drinking barely detected problems in any patient category and are no longer recommended. A suitable alternative appears complex to find; outcomes of this study and the recent literature doubt an added value. Similar problems were found in the CLEFT-Q Jaw at time-point 12 years. Therefore, time-points 15 and 17 years are currently suggested.</p
Substrate-Assisted Catalysis Unifies Two Families of Chitinolytic Enzymes
Hen egg-white lysozyme has long been the paradigm for enzymatic glycosyl hydrolysis with retention of configuration, with a protonated carboxylic acid and a deprotonated carboxylate participating in general acid-base catalysis. In marked contrast, the retaining chitin degrading enzymes from glycosyl hydrolase families 18 and 20 all have a single glutamic acid as the catalytic acid but lack a nucleophile on the enzyme. Both families have a catalytic (βα)8-barrel domain in common. X-ray structures of three different chitinolytic enzymes complexed with substrates or inhibitors identify a retaining mechanism involving a protein acid and the carbonyl oxygen atom of the substrate’s C2 N-acetyl group as the nucleophile. These studies unambiguously demonstrate the distortion of the sugar ring toward a sofa conformation, long postulated as being close to that of the transition state in glycosyl hydrolysis.
The EMT transcription factor ZEB1 governs a fitness-promoting but vulnerable DNA replication stress response
The DNA damage response (DDR) and epithelial-to-mesenchymal transition (EMT) are two crucial cellular programs in cancer biology. While the DDR orchestrates cell cycle progression, DNA repair and cell death, EMT promotes invasiveness, cellular plasticity and intratumor heterogeneity. Therapeutic targeting of EMT transcription factors, such as ZEB1, remains challenging, but tumor-promoting DDR alterations elicit specific vulnerabilities. Using multi-omics, inhibitors and high-content microscopy, we discover a chemoresistant ZEB1 high expressing sub-population (ZEB1hi) with co-rewired cell cycle progression and proficient DDR across tumor entities. ZEB1 stimulates accelerated S-phase entry via CDK6, inflicting endogenous DNA replication stress. However, DDR buildups involving constitutive MRE11-dependent fork resection allow homeostatic cycling and enrichment of ZEB1hi cells during TGFβ-induced EMT and chemotherapy. Thus, ZEB1 promotes G1/S transition to launch a progressive DDR benefitting stress tolerance, which concurrently manifests a targetable vulnerability in chemoresistant ZEB1hi cells. Our study thus highlights the translationally relevant intercept of the DDR and EMT
Encompassing new use cases - level 3.0 of the HUPO-PSI format for molecular interactions.
BACKGROUND: Systems biologists study interaction data to understand the behaviour of whole cell systems, and their environment, at a molecular level. In order to effectively achieve this goal, it is critical that researchers have high quality interaction datasets available to them, in a standard data format, and also a suite of tools with which to analyse such data and form experimentally testable hypotheses from them. The PSI-MI XML standard interchange format was initially published in 2004, and expanded in 2007 to enable the download and interchange of molecular interaction data. PSI-XML2.5 was designed to describe experimental data and to date has fulfilled this basic requirement. However, new use cases have arisen that the format cannot properly accommodate. These include data abstracted from more than one publication such as allosteric/cooperative interactions and protein complexes, dynamic interactions and the need to link kinetic and affinity data to specific mutational changes. RESULTS: The Molecular Interaction workgroup of the HUPO-PSI has extended the existing, well-used XML interchange format for molecular interaction data to meet new use cases and enable the capture of new data types, following extensive community consultation. PSI-MI XML3.0 expands the capabilities of the format beyond simple experimental data, with a concomitant update of the tool suite which serves this format. The format has been implemented by key data producers such as the International Molecular Exchange (IMEx) Consortium of protein interaction databases and the Complex Portal. CONCLUSIONS: PSI-MI XML3.0 has been developed by the data producers, data users, tool developers and database providers who constitute the PSI-MI workgroup. This group now actively supports PSI-MI XML2.5 as the main interchange format for experimental data, PSI-MI XML3.0 which additionally handles more complex data types, and the simpler, tab-delimited MITAB2.5, 2.6 and 2.7 for rapid parsing and download
Capturing variation impact on molecular interactions in the IMEx Consortium mutations data set
The current wealth of genomic variation data identified at nucleotide level presents the challenge of understanding by which mechanisms amino acid variation affects cellular processes. These effects may manifest as distinct phenotypic differences between individuals or result in the development of disease. Physical interactions between molecules are the linking steps underlying most, if not all, cellular processes. Understanding the effects that sequence variation has on a molecule's interactions is a key step towards connecting mechanistic characterization of nonsynonymous variation to phenotype. We present an open access resource created over 14 years by IMEx database curators, featuring 28,000 annotations describing the effect of small sequence changes on physical protein interactions. We describe how this resource was built, the formats in which the data is provided and offer a descriptive analysis of the data set. The data set is publicly available through the IntAct website and is enhanced with every monthly release
Phage T4 SegB protein is a homing endonuclease required for the preferred inheritance of T4 tRNA gene region occurring in co-infection with a related phage
Homing endonucleases initiate nonreciprocal transfer of DNA segments containing their own genes and the flanking sequences by cleaving the recipient DNA. Bacteriophage T4 segB gene, which is located in a cluster of tRNA genes, encodes a protein of unknown function, homologous to homing endonucleases of the GIY-YIG family. We demonstrate that SegB protein is a site-specific endonuclease, which produces mostly 3′ 2-nt protruding ends at its DNA cleavage site. Analysis of SegB cleavage sites suggests that SegB recognizes a 27-bp sequence. It contains 11-bp conserved sequence, which corresponds to a conserved motif of tRNA TψC stem-loop, whereas the remainder of the recognition site is rather degenerate. T4-related phages T2L, RB1 and RB3 contain tRNA gene regions that are homologous to that of phage T4 but lack segB gene and several tRNA genes. In co-infections of phages T4 and T2L, segB gene is inherited with nearly 100% of efficiency. The preferred inheritance depends absolutely on the segB gene integrity and is accompanied by the loss of the T2L tRNA gene region markers. We suggest that SegB is a homing endonuclease that functions to ensure spreading of its own gene and the surrounding tRNA genes among T4-related phages
Safety and efficacy of a dapivirine vaginal ring for HIV prevention in women
BACKGROUND
The incidence of human immunodeficiency virus (HIV) infection remains high
among women in sub-Saharan Africa. We evaluated the safety and efficacy of extended
use of a vaginal ring containing dapivirine for the prevention of HIV infection
in 1959 healthy, sexually active women, 18 to 45 years of age, from seven communities
in South Africa and Uganda.
METHODS
In this randomized, double-blind, placebo-controlled, phase 3 trial, we randomly
assigned participants in a 2:1 ratio to receive vaginal rings containing either 25 mg
of dapivirine or placebo. Participants inserted the rings themselves every 4 weeks
for up to 24 months. The primary efficacy end point was the rate of HIV type 1
(HIV-1) seroconversion.
RESULTS
A total of 77 participants in the dapivirine group underwent HIV-1 seroconversion
during 1888 person-years of follow-up (4.1 seroconversions per 100 person-years),
as compared with 56 in the placebo group who underwent HIV-1 seroconversion
during 917 person-years of follow-up (6.1 seroconversions per 100 person-years).
The incidence of HIV-1 infection was 31% lower in the dapivirine group than in
the placebo group (hazard ratio, 0.69; 95% confidence interval [CI], 0.49 to 0.99; P = 0.04). There was no significant difference in efficacy of the dapivirine ring
among women older than 21 years of age (hazard ratio for infection, 0.63; 95% CI,
0.41 to 0.97) and those 21 years of age or younger (hazard ratio, 0.85; 95% CI, 0.45
to 1.60; P = 0.43 for treatment-by-age interaction). Among participants with HIV-1
infection, nonnucleoside reverse-transcriptase inhibitor resistance mutations were
detected in 14 of 77 participants in the dapivirine group (18.2%) and in 9 of 56
(16.1%) in the placebo group. Serious adverse events occurred more often in the
dapivirine group (in 38 participants [2.9%]) than in the placebo group (in 6 [0.9%]).
However, no clear pattern was identified.
CONCLUSIONS
Among women in sub-Saharan Africa, the dapivirine ring was not associated with
any safety concerns and was associated with a rate of acquisition of HIV-1 infection
that was lower than the rate with placebo.Supported by the International Partnership for Microbicides
(a not-for-profit product-development partnership), which receives
support from the Bill and Melinda Gates Foundation,
Irish Aid, the Ministry of Foreign Affairs of Denmark, the Ministry
of Foreign Affairs of the Netherlands, the Norwegian
Agency for Development Cooperation, the U.K. Department for
International Development, the American people through the
U.S. Agency for International Development, and the President’s
Emergency Plan for AIDS Relief.http://www.nejm.org2017-06-01am2017Family Medicin
Mobile DNA elements in T4 and related phages
Mobile genetic elements are common inhabitants of virtually every genome where they can exert profound influences on genome structure and function in addition to promoting their own spread within and between genomes. Phage T4 and related phage have long served as a model system for understanding the molecular mechanisms by which a certain class of mobile DNA, homing endonucleases, promote their spread. Homing endonucleases are site-specific DNA endonucleases that initiate mobility by introducing double-strand breaks at defined positions in genomes lacking the endonuclease gene, stimulating repair and recombination pathways that mobilize the endonuclease coding region. In phage T4, homing endonucleases were first discovered as encoded within the self-splicing td, nrdB and nrdD introns of T4. Genomic data has revealed that homing endonucleases are extremely widespread in T-even-like phage, as evidenced by the astounding fact that ~11% of the T4 genome encodes homing endonuclease genes, with most of them located outside of self-splicing introns. Detailed studies of the mobile td intron and its encoded endonuclease, I-TevI, have laid the foundation for genetic, biochemical and structural aspects that regulate the mobility process, and more recently have provided insights into regulation of homing endonuclease function. Here, we summarize the current state of knowledge regarding T4-encoded homing endonucleases, with particular emphasis on the td/I-TevI model system. We also discuss recent progress in the biology of free-standing endonucleases, and present areas of future research for this fascinating class of mobile genetic elements
Branched Intermediate Formation Is the Slowest Step in the Protein Splicing Reaction of the Ala1 KlbA Intein from Methanococcus jannaschii
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