41 research outputs found
Functional diversity among cardiolipin binding sites on the mitochondrial ADP/ATP carrier
Lipid-protein interactions play a multitude of essential roles in membrane homeostasis. Mitochondrial membranes have a unique lipid-protein environment that ensures bioenergetic efficiency. Cardiolipin (CL), the signature mitochondrial lipid, plays multiple roles in promoting oxidative phosphorylation (OXPHOS). In the inner mitochondrial membrane, the ADP/ATP carrier (AAC in yeast; adenine nucleotide translocator, ANT in mammals) exchanges ADP and ATP, enabling OXPHOS. AAC/ANT contains three tightly bound CLs, and these interactions are evolutionarily conserved. Here, we investigated the role of these buried CLs in AAC/ANT using a combination of biochemical approaches, native mass spectrometry, and molecular dynamics simulations. We introduced negatively charged mutations into each CL-binding site of yeast Aac2 and established experimentally that the mutations disrupted the CL interactions. While all mutations destabilized Aac2 tertiary structure, transport activity was impaired in a binding site-specific manner. Additionally, we determined that a disease-associated missense mutation in one CL-binding site in human ANT1 compromised its structure and transport activity, resulting in OXPHOS defects. Our findings highlight the conserved significance of CL in AAC/ANT structure and function, directly tied to specific lipid-protein interactions
Interventions to Influence Consulting and Antibiotic Use for Acute Respiratory Tract Infections in Children: A Systematic Review and Meta-Analysis
BACKGROUND: Respiratory tract infections (RTIs) are common in children and generally self-limiting, yet often result in consultations to primary care. Frequent consultations divert resources from care for potentially more serious conditions and increase the opportunity for antibiotic overuse. Overuse of antibiotics is associated with adverse effects and antimicrobial resistance, and has been shown to influence how patients seek care in ensuing illness episodes. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a systematic review and meta-analysis to assess the effectiveness of interventions directed towards parents or caregivers which were designed to influence consulting and antibiotic use for respiratory tract infections (RTIs) in children in primary care. Main outcomes were parental consulting rate, parental knowledge, and proportion of children subsequently consuming antibiotics. Of 5,714 references, 23 studies (representing 20 interventions) met inclusion criteria. Materials designed to engage children in addition to parents were effective in modifying parental knowledge and behaviour, resulting in reductions in consulting rates ranging from 13 to 40%. Providing parents with delayed prescriptions significantly decreased reported antibiotic use (Risk Ratio (RR) 0.46 (0.40, 0.54); moreover, a delayed or no prescribing approach did not diminish parental satisfaction. CONCLUSIONS: IN ORDER TO BE MOST EFFECTIVE, INTERVENTIONS TO INFLUENCE PARENTAL CONSULTING AND ANTIBIOTIC USE SHOULD: engage children, occur prior to an illness episode, employ delayed prescribing, and provide guidance on specific symptoms. These results support the wider implementation of interventions to reduce inappropriate antibiotic use in children
The impact of immediate breast reconstruction on the time to delivery of adjuvant therapy: the iBRA-2 study
Background:
Immediate breast reconstruction (IBR) is routinely offered to improve quality-of-life for women requiring mastectomy, but there are concerns that more complex surgery may delay adjuvant oncological treatments and compromise long-term outcomes. High-quality evidence is lacking. The iBRA-2 study aimed to investigate the impact of IBR on time to adjuvant therapy.
Methods:
Consecutive women undergoing mastectomyâ±âIBR for breast cancer JulyâDecember, 2016 were included. Patient demographics, operative, oncological and complication data were collected. Time from last definitive cancer surgery to first adjuvant treatment for patients undergoing mastectomyâ±âIBR were compared and risk factors associated with delays explored.
Results:
A total of 2540 patients were recruited from 76 centres; 1008 (39.7%) underwent IBR (implant-only [nâ=â675, 26.6%]; pedicled flaps [nâ=â105,4.1%] and free-flaps [nâ=â228, 8.9%]). Complications requiring re-admission or re-operation were significantly more common in patients undergoing IBR than those receiving mastectomy. Adjuvant chemotherapy or radiotherapy was required by 1235 (48.6%) patients. No clinically significant differences were seen in time to adjuvant therapy between patient groups but major complications irrespective of surgery received were significantly associated with treatment delays.
Conclusions:
IBR does not result in clinically significant delays to adjuvant therapy, but post-operative complications are associated with treatment delays. Strategies to minimise complications, including careful patient selection, are required to improve outcomes for patients
Somatic mutations reveal asymmetric cellular dynamics in the early human embryo.
Somatic cells acquire mutations throughout the course of an individual's life. Mutations occurring early in embryogenesis are often present in a substantial proportion of, but not all, cells in postnatal humans and thus have particular characteristics and effects. Depending on their location in the genome and the proportion of cells they are present in, these mosaic mutations can cause a wide range of genetic disease syndromes and predispose carriers to cancer. They have a high chance of being transmitted to offspring as de novo germline mutations and, in principle, can provide insights into early human embryonic cell lineages and their contributions to adult tissues. Although it is known that gross chromosomal abnormalities are remarkably common in early human embryos, our understanding of early embryonic somatic mutations is very limited. Here we use whole-genome sequences of normal blood from 241 adults to identify 163 early embryonic mutations. We estimate that approximately three base substitution mutations occur per cell per cell-doubling event in early human embryogenesis and these are mainly attributable to two known mutational signatures. We used the mutations to reconstruct developmental lineages of adult cells and demonstrate that the two daughter cells of many early embryonic cell-doubling events contribute asymmetrically to adult blood at an approximately 2:1 ratio. This study therefore provides insights into the mutation rates, mutational processes and developmental outcomes of cell dynamics that operate during early human embryogenesis
The glucocorticoid receptor and cortisol levels in pediatric septic shock
Abstract Background There is controversy around the prescription of adjunct corticosteroids in patients with fluid-refractory septic shock, and studies provide mixed results, showing benefit, no benefit, and harm. Traditional means for evaluating whether a patient receives corticosteroids relied on anecdotal experience or measurement of serum cortisol production following stimulation. We set out to measure both serum cortisol and the intracellular signaling receptor for cortisol, the glucocorticoid receptor (GCR), in this group of patients. Methods We enrolled pediatric patients admitted to the pediatric intensive care unit with a diagnosis of systemic inflammatory response syndrome (SIRS), sepsis, or septic shock as well as healthy controls. We measured serum cortisol concentration and GCR expression by flow cytometry in peripheral blood leukocytes on the day of admission and day 3. Results We enrolled 164 patients for analysis. There was no difference between GCR expression comparing SIRS, sepsis, and septic shock. When all patients with septic shock were compared, those patients with a complicated course, defined as two or more organ failures at day 7 or death by day 28, had lower expression of GCR in all peripheral blood leukocytes. Further analysis suggested that patients with the combination of low GCR and high serum cortisol had higher rates of complicated course (75%) compared with the other three possible combinations of GCR and cortisol levels: low GCR and low cortisol (33%), high GCR and high cortisol (33%), and high GCR and low cortisol (13%; P <0.05). Conclusions We show that decreased expression of the GCR correlated with poor outcome from septic shock, particularly in those patients with high serum cortisol. This is consistent with findings from transcriptional studies showing that downregulation of GCR signaling genes portends worse outcome
Increased Expression of Stem Cell Marker Olfactomedin-4 in Gastrointestinal Graft-Versus-Host Disease
Gene silencing in Caenorhabditis elegans by transitive RNA interference
When a cell is exposed to double-stranded RNA (dsRNA), mRNA from the homologous gene is selectively degraded by a process called RNA interference (RNAi). Here, we provide evidence that dsRNA is amplified in Caenorhabditis elegans to ensure a robust RNAi response. Our data suggest a model in which mRNA targeted by RNAi functions as a template for 5' to 3' synthesis of new dsRNA (termed transitive RNAi). Strikingly, the effect is nonautonomous: dsRNA targeted to a gene expressed in one cell type can lead to transitive RNAi-mediated silencing of a second gene expressed in a distinct cell type. These data suggest dsRNA synthesized in vivo can mediate systemic RNAi
The pediatric sepsis biomarker risk model: potential implications for sepsis therapy and biology
Green Proteorhodopsin Reconstituted into Nanoscale Phospholipid Bilayers (Nanodiscs) as Photoactive Monomers
Over 4000 putative proteorhodopsins (PRs) have been identified throughout the oceans and seas of the Earth. The first of these eubacterial rhodopsins was discovered in 2000 and has expanded the family of microbial proton pumps to all three domains of life. With photophysical properties similar to those of bacteriorhodopsin, an archaeal proton pump, PRs are also generating interest for their potential use in various photonic applications. We perform here the first reconstitution of the minimal photoactive PR structure into nanoscale phospholipid bilayers (nanodiscs) to better understand how proteinâprotein and proteinâlipid interactions influence the photophysical properties of PR. Spectral (steady-state and time-resolved UVâvisible spectroscopy) and physical (size-exclusion chromatography and electron microscopy) characterization of these complexes confirms the preparation of a photoactive PR monomer within nanodiscs. Specifically, when embedded within a nanodisc, monomeric PR exhibits a titratable p<i>K</i><sub>a</sub> (6.5â7.1) and photocycle lifetime (âŒ100â200 ms) that are comparable to the detergent-solubilized protein. These ndPRs also produce a photoactive blue-shifted absorbance, centered at 377 or 416 nm, that indicates that proteinâprotein interactions from a PR oligomer are required for a fast photocycle. Moreover, we demonstrate how these model membrane systems allow modulation of the PR photocycle by variation of the discoidal diameter (i.e., 10 or 12 nm), bilayer thickness (i.e., 23 or 26.5 Ă
), and degree of saturation of the lipid acyl chain. Nanodiscs also offer a highly stable environment of relevance to potential device applications