Glaucoma is a chronic and progressive eye disease, commonly associated with elevated intraocular pressure (IOP) and characterized by optic nerve degeneration, cupping of the optic disc, and loss of ...retinal ganglion cells (RGCs). The pathological changes in glaucoma are triggered by multiple mechanisms and both mechanical effects and vascular factors are thought to contribute to the etiology of glaucoma. Various studies have shown that endothelin-1 (ET-1), a vasoactive peptide, acting through its G protein coupled receptors, ET
and ET
, plays a pathophysiologic role in glaucoma. However, the mechanisms by which ET-1 contribute to neurodegeneration remain to be completely understood. Our laboratory and others demonstrated that macitentan (MAC), a pan endothelin receptor antagonist, has neuroprotective effects in rodent models of IOP elevation. The current study aimed to determine if oral administration of a dual endothelin antagonist, macitentan, could promote neuroprotection in an acute model of intravitreal administration of ET-1. We demonstrate that vasoconstriction following the intravitreal administration of ET-1 was attenuated by dietary administration of the ET
/ET
dual receptor antagonist, macitentan (5 mg/kg body weight) in retired breeder Brown Norway rats. ET-1 intravitreal injection produced a 40% loss of RGCs, which was significantly lower in macitentan-treated rats. We also evaluated the expression levels of glial fibrillary acidic protein (GFAP) at 24 h and 7 days post intravitreal administration of ET-1 in Brown Norway rats as well as following ET-1 treatment in cultured human optic nerve head astrocytes. We observed that at the 24 h time point the expression levels of GFAP was upregulated (indicative of glial activation) following intravitreal ET-1 administration in both retina and optic nerve head regions. However, following macitentan administration for 7 days after intravitreal ET-1 administration, we observed an upregulation of GFAP expression, compared to untreated rats injected intravitreally with ET-1 alone. Macitentan treatment in ET-1 administered rats showed protection of RGC somas but was not able to preserve axonal integrity and functionality. The endothelin receptor antagonist, macitentan, has neuroprotective effects in the retinas of Brown Norway rats acting through different mechanisms, including enhancement of RGC survival and reduction of ET-1 mediated vasoconstriction.
To evaluate the effect of technical errors (TEs) on the outcomes after repair of femoral neck fractures in young adults.
Multicenter retrospective clinical study.
26 North American Level 1 Trauma ...Centers.
Skeletally mature patients younger than 50 years of age with 492 femoral neck fractures treated between 2005 and 2017.
Operative repair of femoral neck fracture.
The association between TE (malreduction and deviation from optimal technique) and treatment failure (fixation failure, nonunion, malunion, osteonecrosis, malunion, and revision surgery) were examined using logistic regression analysis.
Overall, a TE was observed in 50% (n = 245/492) of operatively managed femoral neck fractures in young patients. Two or more TEs were observed in 10% of displaced fractures. Treatment failure in displaced fractures occurred in 27% of cases without a TE, 56% of cases with 1 TE, and 86% of cases with 2 or more TEs. TEs were encountered less frequently in treatment of nondisplaced fractures compared with displaced fractures (39% vs. 53%, P < 0.001). Although TE(s) in nondisplaced fractures increased the risk of treatment failure and/or major reconstructive surgery (22% vs. 9%, P < 0.001), they were less frequently associated with treatment failure when compared with displaced fractures with a TE (22% vs. 69% P < 0.001).
TEs were found in half of all femoral neck fractures in young adults undergoing operative repair. Both the occurrence and number of TEs were associated with an increased risk for failure of treatment. Preoperative planning for thoughtful and well-executed reduction and fixation techniques should lead to improved outcomes for young patients with femoral neck fractures. This study should also highlight the need for educational forums to address this subject.
Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
To evaluate whether augmenting traditional fixation with a femoral neck buttress plate (FNBP) improves clinical outcomes in young adults with high-energy displaced femoral neck fractures.
Multicenter ...retrospective matched cohort comparative clinical study.
Twenty-seven North American Level 1 trauma centers.
Adult patients younger than 55 years who sustained a high-energy (nonpathologic) displaced femoral neck fracture.
Operative reduction and stabilization of a displaced femoral neck fracture with (group 1) and without (group 2) an FNBP.
Complications including failed fixation, nonunion, osteonecrosis, malunion, and need for subsequent major reconstructive surgery (early revision of reduction and/or fixation), proximal femoral osteotomy, or arthroplasty.
Of 478 patients younger than 55 years treated operatively for a displaced femoral neck fracture, 11% (n = 51) had the definitive fixation augmented with an FNBP. One or more forms of treatment failure occurred in 29% (n = 15/51) for group 1 and 49% (209/427) for group 2 ( P < 0.01). When FNBP fixation was used, mini-fragment (2.4/2.7 mm) fixation failed significantly more often than small-fragment (3.5 mm) fixation (42% vs. 5%, P < 0.01). Irrespective of plate size, anterior and anteromedial plates failed significantly more often than direct medial plates (75% and 33% vs. 9%, P < 0.001).
The use of a femoral neck buttress plate to augment traditional fixation in displaced femoral neck fractures is associated with improved clinical outcomes, including lower rates of failed fixation, nonunion, osteonecrosis, and need for secondary reconstructive surgery. The benefits of this technique are optimized when a small-fragment (3.5 mm) plate is applied directly to the medial aspect of the femoral neck, avoiding more anterior positioning .
Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
Most mutations in cancer genomes are thought to be acquired after the initiating event, which may cause genomic instability and drive clonal evolution. However, for acute myeloid leukemia (AML), ...normal karyotypes are common, and genomic instability is unusual. To better understand clonal evolution in AML, we sequenced the genomes of M3-AML samples with a known initiating event (PML-RARA) versus the genomes of normal karyotype M1-AML samples and the exomes of hematopoietic stem/progenitor cells (HSPCs) from healthy people. Collectively, the data suggest that most of the mutations found in AML genomes are actually random events that occurred in HSPCs before they acquired the initiating mutation; the mutational history of that cell is “captured” as the clone expands. In many cases, only one or two additional, cooperating mutations are needed to generate the malignant founding clone. Cells from the founding clone can acquire additional cooperating mutations, yielding subclones that can contribute to disease progression and/or relapse.
Display omitted
► Normal HSPCs contain random background mutations that increase with aging ► AML genomes contain hundreds of mutations, but very few are recurrent ► Comparison of M1 and M3 AML genomes identifies initiating versus cooperating mutations ► Most AML mutations are probably background events in HSPCs, “captured” by cloning
Comparison of the genomes of two groups of patients, each with a different form of AML, allows the resolution of potential driver and cooperating mutations in each disease and reveals that the genetic history of all AML cases is marked by random, benign mutations acquired by normal HSPCs as a function of age.
Most patients with acute myeloid leukaemia (AML) die from progressive disease after relapse, which is associated with clonal evolution at the cytogenetic level. To determine the mutational spectrum ...associated with relapse, we sequenced the primary tumour and relapse genomes from eight AML patients, and validated hundreds of somatic mutations using deep sequencing; this allowed us to define clonality and clonal evolution patterns precisely at relapse. In addition to discovering novel, recurrently mutated genes (for example, WAC, SMC3, DIS3, DDX41 and DAXX) in AML, we also found two major clonal evolution patterns during AML relapse: (1) the founding clone in the primary tumour gained mutations and evolved into the relapse clone, or (2) a subclone of the founding clone survived initial therapy, gained additional mutations and expanded at relapse. In all cases, chemotherapy failed to eradicate the founding clone. The comparison of relapse-specific versus primary tumour mutations in all eight cases revealed an increase in transversions, probably due to DNA damage caused by cytotoxic chemotherapy. These data demonstrate that AML relapse is associated with the addition of new mutations and clonal evolution, which is shaped, in part, by the chemotherapy that the patients receive to establish and maintain remissions.
DNMT3A mutations in acute myeloid leukemia Ley, Timothy J; Ding, Li; Walter, Matthew J ...
The New England journal of medicine,
12/2010, Volume:
363, Issue:
25
Journal Article
Peer reviewed
Open access
The genetic alterations responsible for an adverse outcome in most patients with acute myeloid leukemia (AML) are unknown.
Using massively parallel DNA sequencing, we identified a somatic mutation in ...DNMT3A, encoding a DNA methyltransferase, in the genome of cells from a patient with AML with a normal karyotype. We sequenced the exons of DNMT3A in 280 additional patients with de novo AML to define recurring mutations.
A total of 62 of 281 patients (22.1%) had mutations in DNMT3A that were predicted to affect translation. We identified 18 different missense mutations, the most common of which was predicted to affect amino acid R882 (in 37 patients). We also identified six frameshift, six nonsense, and three splice-site mutations and a 1.5-Mbp deletion encompassing DNMT3A. These mutations were highly enriched in the group of patients with an intermediate-risk cytogenetic profile (56 of 166 patients, or 33.7%) but were absent in all 79 patients with a favorable-risk cytogenetic profile (P<0.001 for both comparisons). The median overall survival among patients with DNMT3A mutations was significantly shorter than that among patients without such mutations (12.3 months vs. 41.1 months, P<0.001). DNMT3A mutations were associated with adverse outcomes among patients with an intermediate-risk cytogenetic profile or FLT3 mutations, regardless of age, and were independently associated with a poor outcome in Cox proportional-hazards analysis.
DNMT3A mutations are highly recurrent in patients with de novo AML with an intermediate-risk cytogenetic profile and are independently associated with a poor outcome. (Funded by the National Institutes of Health and others.).
The full complement of DNA mutations that are responsible for the pathogenesis of acute myeloid leukemia (AML) is not yet known.
We used massively parallel DNA sequencing to obtain a very high level ...of coverage (approximately 98%) of a primary, cytogenetically normal, de novo genome for AML with minimal maturation (AML-M1) and a matched normal skin genome.
We identified 12 acquired (somatic) mutations within the coding sequences of genes and 52 somatic point mutations in conserved or regulatory portions of the genome. All mutations appeared to be heterozygous and present in nearly all cells in the tumor sample. Four of the 64 mutations occurred in at least 1 additional AML sample in 188 samples that were tested. Mutations in NRAS and NPM1 had been identified previously in patients with AML, but two other mutations had not been identified. One of these mutations, in the IDH1 gene, was present in 15 of 187 additional AML genomes tested and was strongly associated with normal cytogenetic status; it was present in 13 of 80 cytogenetically normal samples (16%). The other was a nongenic mutation in a genomic region with regulatory potential and conservation in higher mammals; we detected it in one additional AML tumor. The AML genome that we sequenced contains approximately 750 point mutations, of which only a small fraction are likely to be relevant to pathogenesis.
By comparing the sequences of tumor and skin genomes of a patient with AML-M1, we have identified recurring mutations that may be relevant for pathogenesis.
Neural stem cells (NSCs) must exit quiescence to produce neurons; however, our understanding of this process remains constrained by the technical limitations of current technologies. Fluorescence ...lifetime imaging (FLIM) of autofluorescent metabolic cofactors has been used in other cell types to study shifts in cell states driven by metabolic remodeling that change the optical properties of these endogenous fluorophores. Using this non-destructive, live-cell, and label-free strategy, we found that quiescent NSCs (qNSCs) and activated NSCs (aNSCs) have unique autofluorescence profiles. Specifically, qNSCs display an enrichment of autofluorescence localizing to a subset of lysosomes, which can be used as a graded marker of NSC quiescence to predict cell behavior at single-cell resolution. Coupling autofluorescence imaging with single-cell RNA sequencing, we provide resources revealing transcriptional features linked to deep quiescence and rapid NSC activation. Together, we describe an approach for tracking mouse NSC activation state and expand our understanding of adult neurogenesis.
Display omitted
•Autofluorescence is a live-cell and label-free marker of NSC quiescence•Lysosome-localized autofluorescence is enriched in quiescent NSCs•NSC autofluorescence predicts cell behavior in vitro and ex vivo•Autofluorescence imaging paired with scRNA sequencing can reveal quiescence substates
Classical approaches for determining neural stem cell activation state are technically limited, often involving confounding exogenous reagents or sample destruction through lysis or fixation. Overcoming this barrier, Morrow et al. developed a non-destructive, live-cell, and label-free approach for distinguishing quiescent and activated neural stem cells through autofluorescence imaging.
Cognitive decline is a feared aspect of growing old. It is a major contributor to lower quality of life and loss of independence in old age. We investigated the genetic contribution to individual ...differences in nonpathological cognitive ageing in five cohorts of older adults. We undertook a genome-wide association analysis using 549 692 single-nucleotide polymorphisms (SNPs) in 3511 unrelated adults in the Cognitive Ageing Genetics in England and Scotland (CAGES) project. These individuals have detailed longitudinal cognitive data from which phenotypes measuring each individual's cognitive changes were constructed. One SNP--rs2075650, located in TOMM40 (translocase of the outer mitochondrial membrane 40 homolog)--had a genome-wide significant association with cognitive ageing (P=2.5 × 10(-8)). This result was replicated in a meta-analysis of three independent Swedish cohorts (P=2.41 × 10(-6)). An Apolipoprotein E (APOE) haplotype (adjacent to TOMM40), previously associated with cognitive ageing, had a significant effect on cognitive ageing in the CAGES sample (P=2.18 × 10(-8); females, P=1.66 × 10(-11); males, P=0.01). Fine SNP mapping of the TOMM40/APOE region identified both APOE (rs429358; P=3.66 × 10(-11)) and TOMM40 (rs11556505; P=2.45 × 10(-8)) as loci that were associated with cognitive ageing. Imputation and conditional analyses in the discovery and replication cohorts strongly suggest that this effect is due to APOE (rs429358). Functional genomic analysis indicated that SNPs in the TOMM40/APOE region have a functional, regulatory non-protein-coding effect. The APOE region is significantly associated with nonpathological cognitive ageing. The identity and mechanism of one or multiple causal variants remain unclear.
PDF
