A challenge in the treatment of Staphylococcus aureus infections is the high prevalence of methicillin-resistant S. aureus (MRSA) strains and the formation of non-growing, dormant 'persister' ...subpopulations that exhibit high levels of tolerance to antibiotics and have a role in chronic or recurrent infections. As conventional antibiotics are not effective in the treatment of infections caused by such bacteria, novel antibacterial therapeutics are urgently required. Here we used a Caenorhabditis elegans-MRSA infection screen to identify two synthetic retinoids, CD437 and CD1530, which kill both growing and persister MRSA cells by disrupting lipid bilayers. CD437 and CD1530 exhibit high killing rates, synergism with gentamicin, and a low probability of resistance selection. All-atom molecular dynamics simulations demonstrated that the ability of retinoids to penetrate and embed in lipid bilayers correlates with their bactericidal ability. An analogue of CD437 was found to retain anti-persister activity and show an improved cytotoxicity profile. Both CD437 and this analogue, alone or in combination with gentamicin, exhibit considerable efficacy in a mouse model of chronic MRSA infection. With further development and optimization, synthetic retinoids have the potential to become a new class of antimicrobials for the treatment of Gram-positive bacterial infections that are currently difficult to cure.
Gains and losses of DNA are prevalent in cancer and emerge as a consequence of inter-related processes of replication stress, mitotic errors, spindle multipolarity and breakage-fusion-bridge cycles, ...among others, which may lead to chromosomal instability and aneuploidy
. These copy number alterations contribute to cancer initiation, progression and therapeutic resistance
. Here we present a conceptual framework to examine the patterns of copy number alterations in human cancer that is widely applicable to diverse data types, including whole-genome sequencing, whole-exome sequencing, reduced representation bisulfite sequencing, single-cell DNA sequencing and SNP6 microarray data. Deploying this framework to 9,873 cancers representing 33 human cancer types from The Cancer Genome Atlas
revealed a set of 21 copy number signatures that explain the copy number patterns of 97% of samples. Seventeen copy number signatures were attributed to biological phenomena of whole-genome doubling, aneuploidy, loss of heterozygosity, homologous recombination deficiency, chromothripsis and haploidization. The aetiologies of four copy number signatures remain unexplained. Some cancer types harbour amplicon signatures associated with extrachromosomal DNA, disease-specific survival and proto-oncogene gains such as MDM2. In contrast to base-scale mutational signatures, no copy number signature was associated with many known exogenous cancer risk factors. Our results synthesize the global landscape of copy number alterations in human cancer by revealing a diversity of mutational processes that give rise to these alterations.
Tuberous sclerosis complex is a genetic disorder characterized by hamartomatous lesions in multiple organs, frequently involving the kidney. We conducted a retrospective review of the clinical and ...radiographic records of 167 patients with tuberous sclerosis to determine the frequency of renal disease, the likelihood of significant renal morbidity, and the effects of genotype (TSC1 vs TSC2) and gender on renal phenotype. Renal lesions were seen in 57.5% of patients. Of these, angiomyolipoma (AML) occurred in 85.4%, cysts in 44.8%, and renal cell carcinoma in 4.2%. Both AML and cysts were significantly more common and more numerous in TSC2 than in TSC1. AML was significantly more common in female than in male patients, but cysts showed no correlation with gender. Eleven patients developed renal abnormalities during their care in this practice at an average age of onset of 11.3 years (range 3.8–23 years). The frequency and number of renal lesions were positively correlated with age. Interventions, including arterial embolization and nephrectomy, were performed in 11 (6.6%) patients. Among female patients with lymphangioleiomyomatosis, renal AML was universally present. Our findings confirm a high rate of renal involvement; a low rate of serious complications; significant associations between renal involvement, genotype, and gender; and a significant association between renal and pulmonary involvement in female patients.
Sir2 (silent information regulator 2) is a nicotinamide adenine dinucletide-dependent deacetylase required for longevity due to calorie restriction in yeast and Drosophila. In mammals, calorie ...restriction induces a complex pattern of physiological and behavioral changes. Here we report that the mammalian Sir2 ortholog, Sirt1, is required for the induction of a phenotype by calorie restriction in mice.
Vitamin D deficiency is associated with cardiovascular disease, the most common cause of mortality in hemodialysis patients. To investigate the relation between blood levels of 25-hydroxyvitamin D ...(25D) and 1,25-dihydroxyvitamin D (1,25D) with hemodialysis outcomes, we measured baseline vitamin D levels in a cross-sectional analysis of 825 consecutive patients from within a prospective cohort of incident US hemodialysis patients. Of these patients, 78% were considered vitamin D deficient with 18% considered severely deficient. Calcium, phosphorus, and parathyroid hormone levels correlated poorly with 25D and 1,25D concentrations. To test the association between baseline vitamin D levels and 90-day mortality, we selected the next 175 consecutive participants who died within 90 days and compared them to the 750 patients who survived in a nested case–control analysis. While low vitamin D levels were associated with increased mortality, significant interaction was noted between vitamin D levels, subsequent active vitamin D therapy, and survival. Compared to patients with the highest 25D or 1,25D levels who received therapy, untreated deficient patients were at significantly increased risk for early mortality. Our study shows that among incident hemodialysis patients, vitamin D deficiency is common, correlates poorly with other components of mineral metabolism and is associated with increased early mortality.
The integrity of peripheral nerves relies on communication between axons and Schwann cells. The axonal signals that ensure myelin maintenance are distinct from those that direct myelination and are ...largely unknown. Here we show that ablation of the prion protein PrP(C) triggers a chronic demyelinating polyneuropathy (CDP) in four independently targeted mouse strains. Ablation of the neighboring Prnd locus, or inbreeding to four distinct mouse strains, did not modulate the CDP. CDP was triggered by depletion of PrP(C) specifically in neurons, but not in Schwann cells, and was suppressed by PrP(C) expression restricted to neurons but not to Schwann cells. CDP was prevented by PrP(C) variants that undergo proteolytic amino-proximal cleavage, but not by variants that are nonpermissive for cleavage, including secreted PrP(C) lacking its glycolipid membrane anchor. These results indicate that neuronal expression and regulated proteolysis of PrP(C) are essential for myelin maintenance.
We hereby report a 1-year follow-up on eight women in the first North America trial in which stress urinary incontinence (SUI) was treated with muscle-derived stem cell injections. Mean and median ...follow-up in this group was 16.5 and 17 months (range 3–24 months). Improvement in SUI was seen in five of eight women, with one achieving total continence. Onset of improvement was between 3 and 8 months after injection. Cure or improvement continued at a median of 10 months. No serious adverse events were reported.
Undifferentiated sarcomas (USARCs) of adults are diverse, rare, and aggressive soft tissue cancers. Recent sequencing efforts have confirmed that USARCs exhibit one of the highest burdens of ...structural aberrations across human cancer. Here, we sought to unravel the molecular basis of the structural complexity in USARCs by integrating DNA sequencing, ploidy analysis, gene expression, and methylation profiling. We identified whole genome duplication as a prevalent and pernicious force in USARC tumorigenesis. Using mathematical deconvolution strategies to unravel the complex copy-number profiles and mutational timing models we infer distinct evolutionary pathways of these rare cancers. In addition, 15% of tumors exhibited raised mutational burdens that correlated with gene expression signatures of immune infiltration, and good prognosis.
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•Undifferentiated sarcomas contain biologically relevant molecular subgroups•Identification of mismatch repair deficiency open up alternate avenues for therapy•Pseudohaploidization is a recurrent event in undifferentiated sarcomas•Copy-number signatures are useful for inferring states of sarcoma evolution
Steele et al. determine the molecular landscape of undifferentiated sarcomas. They identify tumors with high mutation burdens, which are enriched for activation of immune pathways and have good prognoses, and deduce four tumorigenic routes, all of which begin with driver mutations before whole genome duplication.
The protein-only hypothesis predicts that infectious mammalian prions are composed solely of PrPSc, a misfolded conformer of the normal prion protein, PrPC. However, protein-only PrPSc preparations ...lack significant levels of prion infectivity, leading to the alternative hypothesis that cofactor molecules are required to form infectious prions. Here, we show that prions with parental strain properties and full specific infectivity can be restored from protein-only PrPSc in vitro. The restoration reaction is rapid, potent, and requires bank vole PrPC substrate, post-translational modifications, and cofactor molecules. To our knowledge, this represents the first report in which the essential properties of an infectious mammalian prion have been restored from pure PrP without adaptation. These findings provide evidence for a unified hypothesis of prion infectivity in which the global structure of protein-only PrPSc accurately stores latent infectious and strain information, but cofactor molecules control a reversible switch that unmasks biological infectivity.
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