Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 346
Filtrar
1.
Pharm Res ; 36(12): 170, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31654151

RESUMO

PURPOSE: Many bioactive molecules show a type of solution phase behavior, termed promiscuous aggregation, whereby at micromolar concentrations, colloidal drug-rich aggregates are formed in aqueous solution. These aggregates are known to be a major cause of false positives and false negatives in select enzymatic high-throughput screening assays. The goal of this study was to investigate the impact of drug-rich aggregates on in vitro drug screening metabolism assays. METHODS: Cilnidipine was selected as an aggregate former and its impact on drug metabolism was evaluated against rCYP2D6, rCYP1A2, rCYP2C9 and human liver microsomes. RESULTS: The cilnidipine aggregates were shown to non-specifically inhibit multiple cytochrome P450 enzymes with an IC50 comparable with the IC50 of potent model inhibitors. CONCLUSIONS: This newly demonstrated mode of "promiscuous inhibition" is of great importance as it can lead to false positives during drug metabolism evaluations and thus it needs to be considered in the future to better predict in vivo drug-drug interactions.

2.
Rev Neurosci ; 2019 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-31525161

RESUMO

Infantile spasms (IS) and seizures with focal onset have different clinical expressions, even when electroencephalography (EEG) associated with IS has some degree of focality. Oddly, identical pathology (with, however, age-dependent expression) can lead to IS in one patient vs. focal seizures in another or even in the same, albeit older, patient. We therefore investigated whether the cellular mechanisms underlying seizure initiation are similar in the two instances: spasms vs. focal. We noted that in-common EEG features can include (i) a background of waves at alpha to delta frequencies; (ii) a period of flattening, lasting about a second or more - the electrodecrement (ED); and (iii) often an interval of very fast oscillations (VFO; ~70 Hz or faster) preceding, or at the beginning of, the ED. With IS, VFO temporally coincides with the motor spasm. What is different between the two conditions is this: with IS, the ED reverts to recurring slow waves, as occurring before the ED, whereas with focal seizures the ED instead evolves into an electrographic seizure, containing high-amplitude synchronized bursts, having superimposed VFO. We used in vitro data to help understand these patterns, as such data suggest cellular mechanisms for delta waves, for VFO, for seizure-related burst complexes containing VFO, and, more recently, for the ED. We propose a unifying mechanistic hypothesis - emphasizing the importance of brain pH - to explain the commonalities and differences of EEG signals in IS versus focal seizures.

3.
Crit Care Med ; 47(11): 1582-1590, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31393324

RESUMO

OBJECTIVES: Rapid fluid resuscitation has become standard in sepsis care, despite "low-quality" evidence and absence of guidelines for populations "at risk" for volume overload. Our objectives include as follows: 1) identify predictors of reaching a 30 mL/kg crystalloid bolus within 3 hours of sepsis onset (30by3); 2) assess the impact of 30by3 and fluid dosing on clinical outcomes; 3) examine differences in perceived "at-risk" volume-sensitive populations, including end-stage renal disease, heart failure, obesity, advanced age, or with documentation of volume "overload" by bedside examination. DESIGN: Retrospective cohort study. All outcome analyses controlled for sex, end-stage renal disease, heart failure, sepsis severity (severe sepsis vs septic shock), obesity, Mortality in Emergency Department Sepsis score, and time to antibiotics. SETTING: Urban, tertiary care center between January 1, 2014, and May 31, 2017. PATIENTS: Emergency Department treated adults (age ≥18 yr; n = 1,032) with severe sepsis or septic shock. INTERVENTIONS: Administration of IV fluids by bolus. MEASUREMENTS AND MAIN RESULTS: In total, 509 patients received 30by3 (49.3%). Overall mortality was 17.1% (n = 176), with 20.4% mortality in the shock group. Patients who were elderly (odds ratio, 0.62; 95% CI, 0.46-0.83), male (odds ratio, 0.66; CI, 0.49-0.87), obese (odds ratio, 0.18; CI, 0.13-0.25), or with end-stage renal disease (odds ratio, 0.23; CI, 0.13-0.40), heart failure (odds ratio, 0.42; CI, 0.29-0.60), or documented volume "overload" (odds ratio, 0.30; CI, 0.20-0.45) were less likely to achieve 30by3. Failure to meet 30by3 had increased odds of mortality (odds ratio, 1.52; CI, 1.03-2.24), delayed hypotension (odds ratio, 1.42; CI, 1.02-1.99), and increased ICU stay (~2 d) (ß = 2.0; CI, 0.5-3.6), without differential effects for "at-risk" groups. Higher fluid volumes administered by 3 hours correlated with decreased mortality, with a plateau effect between 35 and 45 mL/kg (p < 0.05). CONCLUSIONS: Failure to reach 30by3 was associated with increased odds of in-hospital mortality, irrespective of comorbidities. Predictors of inadequate resuscitation can be identified, potentially leading to interventions to improve survival. These findings are retrospective and require future validation.

4.
Dis Model Mech ; 12(9)2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31439589

RESUMO

We studied a new amyloid-beta precursor protein (App) knock-in mouse model of Alzheimer's disease (AppNL-G-F ), containing the Swedish KM670/671NL mutation, the Iberian I716F mutation and the Artic E693G mutation, which generates elevated levels of amyloid beta (Aß)40 and Aß42 without the confounds associated with APP overexpression. This enabled us to assess changes in anxiety-related and social behaviours, and neural alterations potentially underlying such changes, driven specifically by Aß accumulation. AppNL-G-F knock-in mice exhibited subtle deficits in tasks assessing social olfaction, but not in social motivation tasks. In anxiety-assessing tasks, AppNL-G-F knock-in mice exhibited: (1) increased thigmotaxis in the open field (OF), yet; (2) reduced closed-arm, and increased open-arm, time in the elevated plus maze (EPM). Their ostensibly anxiogenic OF profile, yet ostensibly anxiolytic EPM profile, could hint at altered cortical mechanisms affecting decision-making (e.g. 'disinhibition'), rather than simple core deficits in emotional motivation. Consistent with this possibility, alterations in microstructure, glutamatergic-dependent gamma oscillations and glutamatergic gene expression were all observed in the prefrontal cortex, but not the amygdala, of AppNL-G-F knock-in mice. Thus, insoluble Aß overexpression drives prefrontal cortical alterations, potentially underlying changes in social and anxiety-related behavioural tasks.This article has an associated First Person interview with the first author of the paper.

5.
Artigo em Inglês | MEDLINE | ID: mdl-31465105

RESUMO

Importance: In the management of differentiated thyroid cancer (DTC), the extent of surgical treatment required for most patients remains controversial and varies widely. This variation may be associated with the Enthusiasm Hypothesis, the notion that geographic differences in use of health care services are driven by the prevalence of physicians with a preference for particular services. Objective: To evaluate the Enthusiasm Hypothesis and its applicability to the variation in the surgical treatment of thyroid cancer in Ontario, Canada. Design, Setting, and Participants: This population-based study obtained electronic data on all health care-associated events for the complete population of insured residents of Ontario, Canada. Patients (n = 28 754) who were 18 years of age or older and underwent an initial therapeutic thyroid surgical procedure for a papillary or follicular carcinoma diagnosis between January 1, 2000, and December 31, 2015, were included. The final data analysis was performed January 31, 2019. Exposures: Therapeutic thyroid cancer surgical procedure. Main Outcomes and Measures: Numbers of surgeons, extent of surgical treatment, and case volumes in 14 geographic regions in Ontario. Results: In total, 28 754 patients with DTC were included, of whom 22 600 (78.6%) were female, with a mean (SD) age of 49 (14) years. The use of total thyroidectomy for DTC varied widely across geographic regions of Ontario, from 45.8% to 77.1% of all cancer cases. More than 90% of the overall variation in practice (total thyroidectomy vs less-than-total thyroidectomy) could be explained by the practices of the high-volume surgeons (enthusiasts) in regions with the highest rates of thyroid cancer diagnosis. Conclusions and Relevance: The Enthusiasm Hypothesis appears to be consistent with the findings of this study. The practices of the high-volume surgeons who were enthusiastic for total thyroidectomy in the geographic regions with the highest rates of thyroid cancer diagnosis may account for the variation in practice across Ontario between 2000 and 2015.

6.
Nature ; 573(7772): 122-125, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31413368

RESUMO

Fossilized eyes permit inferences of the visual capacity of extinct arthropods1-3. However, structural and/or chemical modifications as a result of taphonomic and diagenetic processes can alter the original features, thereby necessitating comparisons with modern species. Here we report the detailed molecular composition and microanatomy of the eyes of 54-million-year-old crane-flies, which together provide a proxy for the interpretation of optical systems in some other ancient arthropods. These well-preserved visual organs comprise calcified corneal lenses that are separated by intervening spaces containing eumelanin pigment. We also show that eumelanin is present in the facet walls of living crane-flies, in which it forms the outermost ommatidial pigment shield in compound eyes incorporating a chitinous cornea. To our knowledge, this is the first record of melanic screening pigments in arthropods, and reveals a fossilization mode in insect eyes that involves a decay-resistant biochrome coupled with early diagenetic mineralization of the ommatidial lenses. The demonstrable secondary calcification of lens cuticle that was initially chitinous has implications for the proposed calcitic corneas of trilobites, which we posit are artefacts of preservation rather than a product of in vivo biomineralization4-7. Although trilobite eyes might have been partly mineralized for mechanical strength, a (more likely) organic composition would have enhanced function via gradient-index optics and increased control of lens shape.

7.
Clin Pharmacol Ther ; 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31356678

RESUMO

We verified a physiologically-based pharmacokinetic (PBPK) model to predict cytochrome P450 3A4/5-mediated drug-drug interactions (DDIs). A midazolam (MDZ)-ketoconazole (KTZ) interaction study in 24 subjects selected by CYP3A5 genotype, and liquid chromatography and mass spectroscopy quantification of CYP3A4/5 abundance from independently acquired and genotyped human liver (n = 136) and small intestinal (N = 12) samples, were conducted. The observed CYP3A5 genetic effect on MDZ systemic and oral clearance was successfully replicated by a mechanistic framework incorporating the proteomics-informed CYP3A abundance and optimized small intestinal CYP3A4 abundance based on MDZ intestinal availability (FG ) of 0.44. Furthermore, combined with a modified KTZ PBPK model, this framework recapitulated the observed geometric mean ratio of MDZ area under the curve (AUCR) following 200 or 400 mg KTZ, which was, respectively, 2.7-3.4 and 3.9-4.7-fold in intravenous administration and 11.4-13.4 and 17.0-19.7-fold in oral administration, with AUCR numerically lower (P > 0.05) in CYP3A5 expressers than nonexpressers. In conclusion, the developed mechanistic framework supports dynamic prediction of CYP3A-mediated DDIs in study planning by bridging DDIs between CYP3A5 expressers and nonexpressers.

8.
Nat Commun ; 10(1): 3109, 2019 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-31337752

RESUMO

Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.

9.
JCI Insight ; 52019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31194698

RESUMO

Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder with variable genetic etiologies. Here we focused on understanding the precise molecular pathology of a single clinical variant in DSP, the gene encoding desmoplakin. We initially identified a novel missense desmoplakin variant (p.R451G) in a patient diagnosed with biventricular ACM. An extensive single-family ACM cohort was assembled, revealing a pattern of coinheritance for R451G desmoplakin and the ACM phenotype. An in vitro model system using patient-derived induced pluripotent stem cell lines showed depressed levels of desmoplakin in the absence of abnormal electrical propagation. Molecular dynamics simulations of desmoplakin R451G revealed no overt structural changes, but a significant loss of intramolecular interactions surrounding a putative calpain target site was observed. Protein degradation assays of recombinant desmoplakin R451G confirmed increased calpain vulnerability. In silico screening identified a subset of 3 additional ACM-linked desmoplakin missense mutations with apparent enhanced calpain susceptibility, predictions that were confirmed experimentally. Like R451G, these mutations are found in families with biventricular ACM. We conclude that augmented calpain-mediated degradation of desmoplakin represents a shared pathological mechanism for select ACM-linked missense variants. This approach for identifying variants with shared molecular pathologies may represent a powerful new strategy for understanding and treating inherited cardiomyopathies.

10.
CPT Pharmacometrics Syst Pharmacol ; 8(9): 685-695, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31215774

RESUMO

Regulatory agencies currently recommend itraconazole (ITZ) as a strong cytochrome P450 3A (CYP3A) inhibitor for clinical drug-drug interaction (DDI) studies. This work by an International Consortium for Innovation and Quality in Pharmaceutical Development working group (WG) is to develop and verify a mechanistic ITZ physiologically-based pharmacokinetic model and provide recommendations for optimal DDI study design based on model simulations. To support model development and verification, in vitro and clinical PK data for ITZ and its metabolites were collected from WG member companies. The model predictions of ITZ DDIs with seven different CYP3A substrates were within the guest criteria for 92% of area under the concentration-time curve ratios and 95% of maximum plasma concentration ratios, thus verifying the model for DDI predictions. The verified model was used to simulate various clinical DDI study scenarios considering formulation, duration of dosing, dose regimen, and food status to recommend the optimal design for maximal inhibitory effect by ITZ.

11.
CPT Pharmacometrics Syst Pharmacol ; 8(9): 664-675, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31250974

RESUMO

The drug-drug interaction profile of atorvastatin confirms that disposition is determined by cytochrome P450 (CYP) 3A4 and organic anion transporting polypeptides (OATPs). Drugs that affect gastric emptying, including dulaglutide, also affect atorvastatin pharmacokinetics (PK). Atorvastatin is a carboxylic acid that exists in equilibrium with a lactone form in vivo. The purpose of this work was to assess gastric acid-mediated lactone equilibration of atorvastatin and incorporate this into a physiologically-based PK (PBPK) model to describe atorvastatin acid, lactone, and their major metabolites. In vitro acid-to-lactone conversion was assessed in simulated gastric fluid and included in the model. The PBPK model was verified with in vivo data including CYP3A4 and OATP inhibition studies. Altering the gastric acid-lactone equilibrium reproduced the change in atorvastatin PK observed with dulaglutide. The model emphasizes the need to include gastric acid-lactone conversion and all major atorvastatin-related species for the prediction of atorvastatin PK.

12.
Methods Mol Biol ; 2003: 201-251, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31218621

RESUMO

Neutron scattering has significant benefits for examining the structure of protein-lipid complexes. Cold (slow) neutrons are nondamaging and predominantly interact with the atomic nucleus, meaning that neutron beams can penetrate deeply into samples, which allows for flexibility in the design of samples studied. Most importantly, there is a strong difference in neutron scattering length (i.e., scattering power) between protium ([Formula: see text], 99.98% natural abundance) and deuterium ([Formula: see text] or D, 0.015%). Through the mixing of H2O and D2O in the samples and in some cases the deuterium labeling of the biomolecules, components within a complex can be hidden or enhanced in the scattering signal. This enables both the overall structure and the relative distribution of components within a complex to be resolved. Lipid-protein complexes are most commonly studied using neutron reflectometry (NR) and small angle neutron scattering (SANS). In this review the methodologies to produce and examine a variety of model biological membrane systems using SANS and NR are detailed. These systems include supported lipid bilayers derived from vesicle dispersions or Langmuir-Blodgett deposition, tethered bilayer systems, membrane protein-lipid complexes and polymer wrapped lipid nanodiscs. The three key stages of any SANS/NR study on model membrane systems-sample preparation, data collection, and analysis-are described together with some background on the techniques themselves.

13.
Nat Microbiol ; 4(10): 1692-1705, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31235958

RESUMO

The Mla pathway is believed to be involved in maintaining the asymmetrical Gram-negative outer membrane via retrograde phospholipid transport. The pathway is composed of three components: the outer membrane MlaA-OmpC/F complex, a soluble periplasmic protein, MlaC, and the inner membrane ATPase, MlaFEDB complex. Here, we solve the crystal structure of MlaC in its phospholipid-free closed apo conformation, revealing a pivoting ß-sheet mechanism that functions to open and close the phospholipid-binding pocket. Using the apo form of MlaC, we provide evidence that the inner-membrane MlaFEDB machinery exports phospholipids to MlaC in the periplasm. Furthermore, we confirm that the phospholipid export process occurs through the MlaD component of the MlaFEDB complex and that this process is independent of ATP. Our data provide evidence of an apparatus for lipid export away from the inner membrane and suggest that the Mla pathway may have a role in anterograde phospholipid transport.

15.
Otol Neurotol ; 40(4): 478-484, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30870361

RESUMO

OBJECTIVE: To investigate future surgery for chronic ear disease in children who underwent tympanostomy tube (TT) placement, compared with non-surgically treated patients and healthy controls. STUDY DESIGN: Retrospective population-based cohort study. SETTING: All hospitals in the Canadian province of Ontario. PATIENTS/INTERVENTION: Of children aged 18 years and younger, three cohorts were constructed: 1) TT: patients who had undergone at least one TT procedure (n = 193,880), 2) No-TT: patients with recurrent physician visits for middle ear concerns who did not undergo TT (n = 203,283), and 3) Control: an age-sex matched control group who had not had TT or physician visits for recurrent middle ear concerns (n = 961,168). MAIN OUTCOME MEASURES: Risk, and odds ratios (ORs) of surgery for chronic ear disease. RESULTS: The TT cohort had a higher risk of tympanoplasty (OR 9.50 versus No-TT, p < 0.001; OR 207.90 versus Control, p < 0.001), ossiculoplasty (OR 3.22 versus No-TT, p < 0.001; OR 84.13 versus Control, p < 0.001), atticotomy (OR 4.41 versus No-TT, p < 0.001; OR 44.78 versus Control, p < 0.001), and mastoidectomy (OR 3.22 versus No-TT, p < 0.001; OR 89.12 versus control, p < 0.001). CONCLUSION: This study describes the population risk of subsequent ear surgeries in TT patients. These TT patients have a significantly higher risk of surgery for chronic ear disease versus those patients with recurrent middle ear disease that did not undergo TT, and age-sex matched controls.

16.
Arthritis Rheumatol ; 71(7): 1101-1111, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30848558

RESUMO

OBJECTIVE: The natural history of nonradiographic axial spondyloarthritis (SpA) is incompletely characterized, and there are concerns that nonsteroidal antiinflammatory drugs provide inadequate disease control in patients with active disease. This study was undertaken to investigate the effects of certolizumab pegol (CZP), an anti-tumor necrosis factor treatment, in patients with nonradiographic axial SpA with objective signs of inflammation. METHODS: In this ongoing parallel-group double-blind study, adults with active disease were recruited from 80 centers in Australia, Europe, North America, and Taiwan, and were randomized 1:1 to receive placebo or CZP (400 mg at weeks 0, 2, and 4, followed by 200 mg every 2 weeks) in addition to nonbiologic background medication (NBBM). Switching to open-label CZP (or other biologic) or making background medication changes was permitted at any point during the trial, although changes before week 12 were discouraged. The primary end point was the proportion of patients achieving major improvement (MI) (i.e., a ≥2.0-point decrease in the score from baseline or achievement of the lowest possible score [0.6]) in the Ankylosing Spondylitis Disease Activity Score (ASDAS) at week 52. RESULTS: A total of 317 patients were randomized to receive placebo plus NBBM (n = 158) or CZP plus NBBM (n = 159). ASDAS-MI at week 52 was achieved in 47.2% (75 of 159) of CZP plus NBBM patients, which was significantly greater (P < 0.0001) than the 7.0% (11 of 158) of placebo plus NBBM patients in whom ASDAS-MI was achieved. Of the placebo plus NBBM patients, 60.8% (96 of 158) switched to open-label treatment before week 52 compared to 12.6% (20 of 159) of the CZP plus NBBM patients. CONCLUSION: Adding CZP to background medication is superior to adding placebo in patients with active nonradiographic axial SpA. These results indicate that remission in nonradiographic axial SpA treated without biologics occurs infrequently, demonstrating the need for treatment beyond nonbiologic therapy.

17.
Am J Hosp Palliat Care ; 36(9): 780-788, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30813738

RESUMO

BACKGROUND: Research demonstrates that the attitudes of religious physicians toward end-of-life care treatment can differ substantially from their nonreligious colleagues. While there are various religious perspectives regarding treatment near the end of life, the attitudes of Muslim physicians in this area are largely unknown. OBJECTIVE: This article attempts to fill in this gap by presenting American Muslim physician attitudes toward end-of-life care decision-making and by examining associations between physician religiosity and these attitudes. METHODS: A randomized national sample of 626 Muslim physicians completed a mailed questionnaire assessing religiosity and end-of-life care attitudes. Religiosity, religious practice, and bioethics resource utilization were analyzed as predictors of quality-of-life considerations, attitudes regarding withholding and withdrawing life-sustaining treatment, and end-of-life treatment recommendations at the bivariate and multivariable level. RESULTS: Two-hundred fifty-five (41% response rate) respondents completed surveys. Most physicians reported that religion was either very or the most important part of their life (89%). Physicians who reported consulting Islamic bioethics literature more often had higher odds of recommending active treatment over hospice care in an end-of-life case vignette. Physicians who were more religious had higher odds of viewing withdrawal of life-sustaining treatment more ethically and psychologically challenging than withholding it and had lower odds of agreeing that one should always comply with a competent patient's request to withdraw life-sustaining treatment. DISCUSSION: Religiosity appears to impact Muslim physician attitudes toward various aspects of end-of-life health-care decision-making. Greater research is needed to evaluate how this relationship manifests itself in patient care conversations and shared clinical decision-making in the hospital.

18.
Head Neck ; 41(7): 2271-2276, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30719797

RESUMO

BACKGROUND: Distant metastases (DM) are a leading cause of death for patients with oropharyngeal cancer (OPSCC). The objective of this study was to compare the rates of DM after chemoradiotherapy (CRT) and radiotherapy alone (RT) in patients with human papillomavirus (HPV)-positive and HPV-negative OPSCC. METHOD: In a retrospective population-based study of 525 patients across Ontario, Canada, in 1998/99/03/04, we compared treatment effectiveness using cumulative incidence function curves and cause-specific Cox regression models. RESULTS: Sixty of 525 patients developed DM. There was no difference in rates (overall 10%-15%) between HPV-positive and HPV-negative patients or between CRT- and RT-treated patients. CRT reduced the risk of DM for the 15% of all HPV-positive patients with higher risk (T4 and/or N3) and not for HPV-negative patients (hazard ratio, 1.82 [0.65-5.07]). CONCLUSION: The addition of platin-based chemotherapy to conventional RT did not decrease the rates of DM in the majority of patients with HPV-positive or in HPV-negative OPSSC.

19.
Sci Rep ; 9(1): 1813, 2019 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-30755655

RESUMO

Biological characterisation of membrane proteins lags behind that of soluble proteins. This reflects issues with the traditional use of detergents for extraction, as the surrounding lipids are generally lost, with adverse structural and functional consequences. In contrast, styrene maleic acid (SMA) copolymers offer a detergent-free method for biological membrane solubilisation to produce SMA-lipid particles (SMALPs) containing membrane proteins together with their surrounding lipid environment. We report the development of a reverse-phase LC-MS/MS method for bacterial phospholipids and the first comparison of the profiles of SMALP co-extracted phospholipids from three exemplar bacterial membrane proteins with different topographies: FtsA (associated membrane protein), ZipA (single transmembrane helix), and PgpB (integral membrane protein). The data showed that while SMA treatment per se did not preferentially extract specific phospholipids from the membrane, SMALP-extracted ZipA showed an enrichment in phosphatidylethanolamines and depletion in cardiolipins compared to the bulk membrane lipid. Comparison of the phospholipid profiles of the 3 SMALP-extracted proteins revealed distinct lipid compositions for each protein: ZipA and PgpB were similar, but in FtsA samples longer chain phosphatidylglycerols and phosphatidylethanolamines were more abundant. This method offers novel information on the phospholipid interactions of these membrane proteins.

20.
Otol Neurotol ; 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30789567

RESUMO

OBJECTIVE: To investigate future surgery for chronic ear disease in children who underwent tympanostomy tube (TT) placement, compared with non-surgically treated patients and healthy controls. STUDY DESIGN: Retrospective population-based cohort study. SETTING: All hospitals in the Canadian province of Ontario. PATIENTS/INTERVENTION: Of children aged 18 years and younger, three cohorts were constructed: 1) TT: patients who had undergone at least one TT procedure (n = 193,880), 2) No-TT: patients with recurrent physician visits for middle ear concerns who did not undergo TT (n = 203,283), and 3) Control: an age-sex matched control group who had not had TT or physician visits for recurrent middle ear concerns (n = 961,168). MAIN OUTCOME MEASURES: Risk, and odds ratios (ORs) of surgery for chronic ear disease. RESULTS: The TT cohort had a higher risk of tympanoplasty (OR 9.50 versus No-TT, p < 0.001; OR 207.90 versus Control, p < 0.001), ossiculoplasty (OR 3.22 versus No-TT, p < 0.001; OR 84.13 versus Control, p < 0.001), atticotomy (OR 4.41 versus No-TT, p < 0.001; OR 44.78 versus Control, p < 0.001), and mastoidectomy (OR 3.22 versus No-TT, p < 0.001; OR 89.12 versus control, p < 0.001). CONCLUSION: This study describes the population risk of subsequent ear surgeries in TT patients. These TT patients have a significantly higher risk of surgery for chronic ear disease versus those patients with recurrent middle ear disease that did not undergo TT, and age-sex matched controls.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA