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1.
Curr Atheroscler Rep ; 23(1): 3, 2021 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-33392801

RESUMO

PURPOSE OF REVIEW: Adoption of poor lifestyles (inactivity and energy-dense diets) has driven the worldwide increase in the metabolic syndrome, type 2 diabetes mellitus and non-alcoholic steatohepatitis (NASH). Of the defining features of the metabolic syndrome, an atherogenic dyslipidaemia characterised by elevated triglycerides (TG) and low plasma concentration of high-density lipoprotein cholesterol is a major driver of risk for atherosclerotic cardiovascular disease. Beyond lifestyle intervention and statins, targeting the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARα) is a therapeutic option. However, current PPARα agonists (fibrates) have limitations, including safety issues and the lack of definitive evidence for cardiovascular benefit. Modulating the ligand structure to enhance binding at the PPARα receptor, with the aim of maximising beneficial effects and minimising adverse effects, underlies the SPPARMα concept. RECENT FINDINGS: This review discusses the history of SPPARM development, latterly focusing on evidence for the first licensed SPPARMα, pemafibrate. Evidence from animal models of hypertriglyceridaemia or NASH, as well as clinical trials in patients with atherogenic dyslipidaemia, are overviewed. The available data set the scene for therapeutic application of SPPARMα in the metabolic syndrome, and possibly, NASH. The outstanding question, which has so far eluded fibrates in the setting of current evidence-based therapy including statins, is whether treatment with pemafibrate significantly reduces cardiovascular events in patients with atherogenic dyslipidaemia. The PROMINENT study in patients with type 2 diabetes mellitus and this dyslipidaemia is critical to evaluating this.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33414230

RESUMO

BACKGROUND AND PURPOSE: Traditional statistical models and pretreatment scoring systems have been used to predict the outcome for acute ischemic stroke patients (AIS). Our aim was to select the most relevant features in terms of outcome prediction on the basis of machine learning algorithms for patients with acute ischemic stroke and to compare the performance between multiple models and the Stroke Prognostication Using Age and National Institutes of Health Stroke Scale (SPAN-100) index model. MATERIALS AND METHODS: A retrospective multicenter cohort of 1431 patients with acute ischemic stroke was subdivided into recanalized and nonrecanalized patients. Extreme Gradient Boosting machine learning models were built to predict the mRS score at 90 days using clinical, imaging, combined, and best-performing features. Feature selection was performed using the relative weight and frequency of occurrence in the models. The model with the best performance was compared with the SPAN-100 index model using area under the receiver operating curve analysis. RESULTS: In 3 groups of patients, the baseline NIHSS was the most significant predictor of outcome among all the parameters, with relative weights of 0.36∼0.69; ischemic core volume on CTP ranked as the most important imaging biomarker with relative weights of 0.29∼0.47. The model with the best-performing features had a better performance than the other machine learning models. The area under the curve of the model with the best-performing features was higher than SPAN-100 model and reached statistical significance for the total (P < .05) and the nonrecanalized patients (P < .001). CONCLUSIONS: Machine learning-based feature selection can identify parameters with higher performance in outcome prediction. Machine learning models with the best-performing features, especially advanced CTP data, had superior performance of the recovery outcome prediction for patients with stroke at admission in comparison with SPAN-100.

3.
Eur J Neurol ; 28(1): 192-201, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32918305

RESUMO

BACKGROUND AND PURPOSE: Hierarchical clustering, a common 'unsupervised' machine-learning algorithm, is advantageous for exploring potential underlying aetiology in particularly heterogeneous diseases. We investigated potential embolic sources in embolic stroke of undetermined source (ESUS) using a data-driven machine-learning method, and explored variation in stroke recurrence between clusters. METHODS: We used a hierarchical k-means clustering algorithm on patients' baseline data, which assigned each individual into a unique clustering group, using a minimum-variance method to calculate the similarity between ESUS patients based on all baseline features. Potential embolic sources were categorised into atrial cardiopathy, atrial fibrillation, arterial disease, left ventricular disease, cardiac valvulopathy, patent foramen ovale (PFO) and cancer. RESULTS: Among 800 consecutive ESUS patients (43.3% women, median age 67 years), the optimal number of clusters was four. Left ventricular disease was most prevalent in cluster 1 (present in all patients) and perfectly associated with cluster 1. PFO was most prevalent in cluster 2 (38.9% of patients) and associated significantly with increased likelihood of cluster 2 [adjusted odds ratio: 2.69, 95% confidence interval (CI): 1.64-4.41]. Arterial disease was most prevalent in cluster 3 (57.7%) and associated with increased likelihood of cluster 3 (adjusted odds ratio: 2.21, 95% CI: 1.43-3.13). Atrial cardiopathy was most prevalent in cluster 4 (100%) and perfectly associated with cluster 4. Cluster 3 was the largest cluster involving 53.7% of patients. Atrial fibrillation was not significantly associated with any cluster. CONCLUSIONS: This data-driven machine-learning analysis identified four clusters of ESUS that were strongly associated with arterial disease, atrial cardiopathy, PFO and left ventricular disease, respectively. More than half of the patients were assigned to the cluster associated with arterial disease.

4.
Diabetes Metab Syndr ; 15(1): 149-157, 2020 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-33352454

RESUMO

BACKGROUND AND AIMS: We describe the characteristics and short-term prognosis of in-patients with diabetes and COVID-19 admitted to a Belgian academic care center. METHODS: We retrospectively reviewed the data on admission from patients with known or newly-diagnosed diabetes and confirmed COVID-19. First, survivors were compared to non-survivors to study the predictive factors of in-hospital death in patients with diabetes. Secondly, diabetic patients with SARS-CoV-2 pneumonia were matched for age and sex with non-diabetic patients with SARS-CoV-2 pneumonia, to study the prognosis and predictive factors of in-hospital death related to diabetes. RESULTS: Seventy-three diabetic patients were included. Mean age was 69 (±14) years. Women accounted for 52%. Most patients had type 2 diabetes (89.0%), long-term complications of hyperglycemia (59.1%), and hypertension (80.8%). The case-fatality rate (CFR) was 15%. Non-survivors had more severe pneumonia based on imaging (p 0.029) and were less often treated with metformin (p 0.036). In patients with SARS-CoV-2 pneumonia, CFR was 15.6% in diabetic (n = 64) and 25.0% in non-diabetic patients (n = 128), the difference being non-significant (p 0.194). Predictive factors of in-hospital death were elevated white blood cells count (HR 9.4, CI 1.50-58.8, p 0.016) and severe pneumonia on imaging (HR 25.0, CI 1.34-466, p 0.031) in diabetic patients, and cognitive impairment (HR 5.80, CI 1.61-20.9, p 0.007) and cardiovascular disease (HR 5.63, CI 1.54-20.6, p 0.009) in non-diabetic patients. CONCLUSION: In this monocentric cohort from Belgium, diabetic in-patients with COVID-19 had mostly type 2 diabetes, prevalent hyperglycemia-related vascular complications and comorbidities including hypertension. In this cohort, the CFR was not statistically different between patients with and without diabetes.

5.
Artigo em Inglês | MEDLINE | ID: mdl-33290851

RESUMO

BACKGROUND: The Popeye sign is a frequently reported finding following LHB surgery and may be more often detected by doctors than by patients. This study investigates agreement between patients and doctors regarding the presence of a Popeye sign following LHB surgery. METHOD: This Inter-observer study investigates agreement between patients and consulting physicians with regard to assessment of a Popeye sign in patients following LHB surgery. Furthermore, this was compared with assessments by non-consulting physicians (observers) using digital photographs of the operated arm, taken both preoperatively and postoperatively. Data about gender, age and BMI were collected to investigate their role in doctor's reporting of a Popeye sign. Patient's dissatisfaction with a Popeye sign in the operated arm was evaluated as well. RESULTS: Ninety seven patients (mean age 61 ± 6.0 years, 62% male) underwent LHB surgery. A Popeye sign was reported by 2 patients (2%) as opposed to 32 cases (40%) by consulting physicians, of which only one case was in agreement. Krippendorff's alpha (Kalpha) for agreement between observers for preoperative photographs was 0.074 (95%CI -0.277 to 0.382) and 0.495 (95%CI 0.317 to 0.659) for postoperative cases. Kalpha between observers and consulting physicians for pre and postoperative cases were 0.033 (95%CI -970 to 0.642) and 0.499 (95%CI 0.265 to 0.699) respectively. Phi coefficient analysis showed a moderate, statistically significant correlation between male sex and Popeye sign identification. Rank-biserial calculation revealed negligible correlation between BMI and age with regard to detecting a Popeye sign by both consulting physicians and observers. Dissatisfaction about swelling in the upper arm was reported in one case, however in location that did not correspond to the location of a Popeye sign. CONCLUSION: The Popeye sign is more often identified by doctors than by patients after undergoing LHB surgery. BMI and age are not related to the detection of a Popeye sign, but sex is moderately correlated. Together with the low percentage of dissatisfaction of patients with this swelling, this signifies that a Popeye sign seems to be a doctor's rather than a patient's problem.

6.
Ecology ; : e03268, 2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-33326603

RESUMO

In northern climates, spring is a time of rapid environmental change: for migrating terrestrial animals, melting snow facilitates foraging and travel, and newly-emergent vegetation provides a valuable nutritional resource. These changes result in selection on the timing of important life-history events such as migration and parturition occurring when high-quality resources are most abundant. We examined the timing of female caribou (Rangifer tarandus, n = 94) migration and parturition in five herds across seven years in Newfoundland, Canada as a function of two measures of environmental change-snowmelt and vegetation green-up. We generated resource selection functions to test whether caribou selected for areas associated with snowmelt and green-up during migration and following calving. We found that caribou migrated approximately one week prior to snowmelt, with the flush of emergent vegetation occurring during the weeks following parturition. The results indicate that caribou "jump" the green wave of emergent forage and do so by tracking the receding edge of melting snow, likely reducing movement and foraging costs related to snow cover. Our research further broadens the ecological scope of resource tracking in animals. We demonstrate that resource tracking extends beyond resources directly related to foraging to those related to movement. We also show that snowmelt provides an environmental cue that may provide a buffer against changing environmental conditions.

7.
ESC Heart Fail ; 2020 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-33225620

RESUMO

AIMS: Acutely decompensated heart failure (HF) (ADHF) is a common cause of hospitalization and mortality worldwide. This study explores the epidemiology and prognostic factors of ADHF in Cameroonian patients. METHODS AND RESULTS: This was a retrospective study conducted between January 2003 and December 2013 from the medical files of patients followed at the intensive care and cardiovascular units of Douala General Hospital in Cameroon. Clinical, electrocardiographic, echocardiographic, and biological data were collected from 142 patients (58.5% men; mean age 58 ± 14 years) hospitalized for ADHF with reduced ejection fraction (HFrEF), whose left ventricular ejection fraction was <50%, or alternatively whose shortening fraction was <28%, both assessed by echocardiography. The commonest risk factors associated with HFrEF were hypertension (59.2%), diabetes mellitus (16.2%), tobacco use (14.1%), and dyslipidaemia (7.7%), respectively. The major causes of HF in hospitalized patients were hypertensive heart disease (40%, n = 57); hypertrophic cardiomyopathy (33.8%, n = 48); and ischemic heart disease (21.8%, n = 31). The most frequent comorbid conditions were atrial fibrillation (25.4%, n = 36) and chronic kidney disease (18.3%, n = 26). Major biological abnormalities included increased bilirubinemia >12 mg/L (87.5%, n = 124); hyperuricaemia >70 mg/L (84.9%, n = 121); elevated serum creatinine (65.6%, n = 93); anaemia (59.1%, n = 84); hyperglycaemia on admission >1.8 g/L (42.3%, n = 60); and hyponatraemia <135 mEq/L (26.8%, n = 38). At admission, 33.8% (n = 48) of patients had no pharmacological treatment for HF. The most frequently used therapies upon admission included furosemide (50%, n = 71), angiotensin-converting enzyme inhibitors (ACEIs; 40.1%, n = 57); spironolactone (35.2%, n = 50); digoxin (26%, n = 37); beta-blockers (17.7%, n = 25); angiotensin-receptor blockers (ARBs; 7%, n = 10); and nitrates (7.0%). The overall in-hospital mortality rate was 20.4%. Factors associated with poor prognosis were systolic blood pressure <90 mmHg [odds ratio (OR) 3.88; confidence interval (CI) 1.36-11.05, P = 0.011], left ventricular ejection fraction <20% (OR 7.48; CI 2.84-19.71, P < 0.001), decreased renal function (OR 1.03; CI 1.00-1.05, P = 0.026), dobutamine use for cardiogenic shock (OR 2.74;CI 1.00-7.47, P = 0.049), pleural fluid effusion (OR 3.46; CI 1.07-11.20, P = 0.038), and prothrombin time <50% (OR 3.60; CI 1.11-11.68, P = 0.033). The use of ACEIs/ARBs was associated with reduced in-hospital mortality rate (OR 0.17; CI 0.02-0.81, P = 0.006). CONCLUSIONS: Hypertensive heart disease, hypertrophic cardiomyopathy, and ischemic heart disease are the commonest causes of HF in this Cameroonian population. ADHF is associated with high in-hospital mortality in Cameroon. Hypotension, severe left ventricular systolic dysfunction, renal function impairment, and dobutamine administration were associated with worst acute HF outcomes. ACEIs/ARBs use was associated with improved survival.

8.
JNCI Cancer Spectr ; 4(5): pkaa049, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33134829

RESUMO

Background: Brain tumors represent an important cause of cancer-related death in adolescents and young adults. Most are diagnosed in low-income and middle-income countries. We aimed to conduct the first, to our knowledge, systematic review of time trends and geographical variation in survival in this age group. Methods: We included observational studies describing population-based survival from astrocytic tumors in patients aged 15-39 years. We queried 6 electronic databases from database inception to December 31, 2019. This review is registered with PROSPERO, number CRD42018111981. Results: Among 5640 retrieved records, 20 studies fulfilled the inclusion criteria. All but 1 study focused on high-income countries. Five-year survival from astrocytoma (broad morphology group) mostly varied between 48.0% and 71.0% (1973-2004) without clear trends or geographic differences. Adolescents with astrocytoma had better outcomes than young adults, but survival values were similar when nonmalignant tumors were excluded. During 2002-2007, 5-year survival for World Health Organization grade I-II tumors was in the range of 72.6%-89.1% in England, Germany, and the United States but lower in Southeastern Europe (59.0%). Five-year survival for anaplastic astrocytoma varied between 39.6% and 55.4% (2002-2007). Five-year survival from glioblastoma was in the range of 14.2%-23.1% (1991-2009). Conclusions: Survival from astrocytic tumors remained somewhat steady over time, with little change between 1973 and 2009. Survival disparities were difficult to examine, because nearly all the studies were conducted in affluent countries. Studies often adopted the International Classification of Childhood Cancer, which, however, did not allow to accurately describe variation in survival. Larger studies are warranted, including underrepresented populations and providing more recent survival estimates.

9.
J Biomol Struct Dyn ; : 1-13, 2020 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-33146078

RESUMO

Glioblastoma is an aggressive primary tumor of the central nervous system (CNS). Is the most aggressive among infiltrative gliomas arising from the CNS. This tumor has low patient survival rate and several studies aiming at developing new drugs have increased. Patients with this cancer type face significant morbidity and mortality. This study evaluated the antineoplastic activity of synthetic chalcones (3a-3f) using in vitro glioblastoma models and molecular modeling. Cytotoxicity assay showed that Astrocitoma Hospital Ofir Loyola No 1 (AHOL1) and Uppsala 87 neoplastic glioblastoma lines (U87) cellular viability were significantly reduced compared to Healthy human fibroblasts cell lines (AN27) when exposed to chalcones. Interaction with the serine amino acid was present in the most promising and the reference binder docking, suggesting its importance inhibiting cell growth. Comparative analysis between the reference ligands and the molecules showed that the amino acid LYS352 present in all fittings, suggesting that this is the main amino acid for interaction with tubulin and are consistent with those in cytotoxicity assay, suggesting antineoplastic potential in glioblastoma. Long trajectory molecular dynamics studies were also carried out in order to investigate stability and conformations amongst the chalcones bound tubulin as well, in comparison to doxorubicin (here used as control), however future studies are needed to further assess the mechanism of inhibition of chalcones used in this investigation. Communicated by Ramaswamy H. Sarma.

10.
Am J Trop Med Hyg ; 103(6): 2419-2428, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33009770

RESUMO

Little is known about the clinical features and outcomes of SARS-CoV-2 infection in Africa. We conducted a retrospective cohort study of patients hospitalized for COVID-19 between March 10, 2020 and July 31, 2020 at seven hospitals in Kinshasa, Democratic Republic of the Congo (DRC). Outcomes included clinical improvement within 30 days (primary) and in-hospital mortality (secondary). Of 766 confirmed COVID-19 cases, 500 (65.6%) were male, with a median (interquartile range [IQR]) age of 46 (34-58) years. One hundred ninety-one (25%) patients had severe/critical disease requiring admission in the intensive care unit (ICU). Six hundred twenty patients (80.9%) improved and were discharged within 30 days of admission. Overall in-hospital mortality was 13.2% (95% CI: 10.9-15.8), and almost 50% among those in the ICU. Independent risk factors for death were age < 20 years (adjusted hazard ratio [aHR] = 6.62, 95% CI: 1.85-23.64), 40-59 years (aHR = 4.45, 95% CI: 1.83-10.79), and ≥ 60 years (aHR = 13.63, 95% CI: 5.70-32.60) compared with those aged 20-39 years, with obesity (aHR = 2.30, 95% CI: 1.24-4.27), and with chronic kidney disease (aHR = 5.33, 95% CI: 1.85-15.35). In marginal structural model analysis, there was no statistically significant difference in odds of clinical improvement (adjusted odds ratio [aOR] = 1.53, 95% CI: 0.88-2.67, P = 0.132) nor risk of death (aOR = 0.65, 95% CI: 0.35-1.20) when comparing the use of chloroquine/azithromycin versus other treatments. In this DRC study, the high mortality among patients aged < 20 years and with severe/critical disease is of great concern, and requires further research for confirmation and targeted interventions.


Assuntos
/epidemiologia , Mortalidade Hospitalar/tendências , Pandemias , /patogenicidade , Adolescente , Adulto , Doenças Assintomáticas , Azitromicina/uso terapêutico , /tratamento farmacológico , Cloroquina/uso terapêutico , República Democrática do Congo/epidemiologia , Combinação de Medicamentos , Enoxaparina/uso terapêutico , Feminino , Hospitalização/estatística & dados numéricos , Hospitais , Humanos , Unidades de Terapia Intensiva , Lopinavir/uso terapêutico , Masculino , Pessoa de Meia-Idade , Obesidade/diagnóstico , Obesidade/fisiopatologia , Obesidade/virologia , Alta do Paciente/estatística & dados numéricos , Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/fisiopatologia , Insuficiência Renal Crônica/virologia , Estudos Retrospectivos , Fatores de Risco , Ritonavir/uso terapêutico , Índice de Gravidade de Doença , Resultado do Tratamento
11.
Nature ; 587(7833): 205-209, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33106686

RESUMO

An asteroid's history is determined in large part by its strength against collisions with other objects1,2 (impact strength). Laboratory experiments on centimetre-scale meteorites3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale4,5. In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples6 and images of the asteroid (25143) Itokawa7. It has not yet been possible, however, to assess directly the impact strength, and thus the absolute surface age, of the boulders that constitute the building blocks of a rubble-pile asteroid. Here we report an analysis of the size and depth of craters observed on boulders on the asteroid (101955) Bennu. We show that the impact strength of metre-sized boulders is 0.44 to 1.7 megapascals, which is low compared to that of solid terrestrial materials. We infer that Bennu's metre-sized boulders record its history of impact by millimetre- to centimetre-scale objects in near-Earth space. We conclude that this population of near-Earth impactors has a size frequency distribution similar to that of metre-scale bolides and originates from the asteroidal population. Our results indicate that Bennu has been dynamically decoupled from the main asteroid belt for 1.75 ± 0.75 million years.

12.
J Arthroplasty ; 2020 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-33097337

RESUMO

BACKGROUND: Intra-articular hyaluronic acid (IAHA) can be injected into an osteoarthritic hip joint to reduce pain and to improve functionality. Several studies report IAHA to be safe, with minor adverse effects that normally disappear spontaneously within a week. However, intra-articular corticosteroids prior to total hip arthroplasty (THA) have been associated with increased infection rates. This association has never been investigated for IAHA and THA. We aimed to assess the influence of IAHA on the outcome of THA, with an emphasis on periprosthetic joint infection (PJI). METHODS: At a mean follow-up of 52 months (±18), we compared complication rates, including superficial and deep PJIs, of THA in patients who received an IAHA injection ≤6 months prior to surgery (injection group) with that of patients undergoing THA without any previous injection in the ipsilateral hip (control group). One hundred thirteen patients (118 hips) could be retrospectively included in the injection group, and 452 patients (495 hips) in the control group. RESULTS: No differences in baseline characteristics nor risk factors for PJI between the 2 groups were found. The clinical outcomes in terms of VAS pain scores (1.4 vs 1.7 points, P = .11), modified Harris Hip Scores (77 vs 75 points, P = .09), and Hip disability and Osteoarthritis Outcome Scores (79 vs 76 points, P = .24) did not differ between the injection group and the control group. Also, complications in terms of persistent wound leakage (0% vs 1.2%, P = .60), thromboembolic events (0% vs 0.6%, P = 1.00), periprosthetic fractures (1.7% vs 1.2%, P = .65), and dislocations (0% vs 0.4%, P = 1.00) did not differ. However, in the injection group there was a higher rate of PJIs (4% vs 0%, P < .001) and postoperative wound infections (9% vs 3%, P = .01), compared to the control group. CONCLUSION: Our findings suggest that IAHA performed 6 months or less prior to THA may pose a risk for increased rates of PJI. We recommend refraining from performing THA within 6 months after IAHA administration.

13.
BMJ Open ; 10(9): e036311, 2020 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-32998916

RESUMO

Patient and public involvement and engagement has become an essential element of health research, ensuring aims and outputs are worthwhile and relevant. However, research involving secondary data analyses does not present immediately obvious ways to involve patients and the public. Innovative approaches to ensure their involvement is meaningful and effective are required.The Cancer Survival Group cohosted a full-day meeting with the National Cancer Research Institute Consumer Forum-a group of patients and carers. This included the Forum's 'Dragons' Den': a small-group session in which their members provided insight, advice and ideas on current or planned research in the Cancer Survival Group.We investigated this activity as an example of effective patient involvement, with the aim of developing broad recommendations to improve epidemiological/quantitative research by involving patients and carers as directly as possible.In addition to quantitative data captured through evaluation forms completed after the event, we used semistructured interviews of a sample of participants to evaluate the effectiveness of the session and to learn lessons. The interviews were analysed to identify broad or recurrent themes and recommendations.Feedback was overwhelmingly positive, and some impacts on the research projects were identified. Interviewees commented on overall expectations and experiences, as well as specifics of room layout, timing of the session, composition of groups, effectiveness of the facilitation and content of discussions.We present a summary of our findings as a guide for other researchers, including recommendations for improvement gleaned from the interviews. The value to researchers of hosting and participating in such activities was clear. We developed recommendations that should help to improve future events for ourselves and for others who wish to conduct similar activities, which in turn may lead to more concrete benefits for research and patients.

14.
J Geophys Res Planets ; 125(8): e2019JE006282, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32999798

RESUMO

Asteroid (101955) Bennu, a near-Earth object with a primitive carbonaceous chondrite-like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles <10 cm on temporary orbits around Bennu. Here we examine whether these events could have been produced by sporadic meteoroid impacts using the National Aeronautics and Space Administration's (NASA) Meteoroid Engineering Model 3.0. Most projectiles that impact Bennu come from nearly isotropic or Jupiter-family comets and have evolved toward the Sun by Poynting-Robertson drag. We find that 7,000-J impacts on Bennu occur with a biweekly cadence near perihelion, with a preference to strike in the late afternoon (~6 pm local time). This timing matches observations. Crater scaling laws also indicate that these impact energies can reproduce the sizes and masses of the largest observed particles, provided the surface has the cohesive properties of weak, porous materials. Bennu's ejection events could be caused by the same kinds of meteoroid impacts that created the Moon's asymmetric debris cloud observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE). Our findings also suggest that fewer ejection events should take place as Bennu moves further away from the Sun, a result that can be tested with future observations.

15.
Sci Adv ; 6(41)2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33033036

RESUMO

The gravity field of a small body provides insight into its internal mass distribution. We used two approaches to measure the gravity field of the rubble-pile asteroid (101955) Bennu: (i) tracking and modeling the spacecraft in orbit about the asteroid and (ii) tracking and modeling pebble-sized particles naturally ejected from Bennu's surface into sustained orbits. These approaches yield statistically consistent results up to degree and order 3, with the particle-based field being statistically significant up to degree and order 9. Comparisons with a constant-density shape model show that Bennu has a heterogeneous mass distribution. These deviations can be modeled with lower densities at Bennu's equatorial bulge and center. The lower-density equator is consistent with recent migration and redistribution of material. The lower-density center is consistent with a past period of rapid rotation, either from a previous Yarkovsky-O'Keefe-Radzievskii-Paddack cycle or arising during Bennu's accretion following the disruption of its parent body.

16.
Sci Adv ; 6(41)2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33033038

RESUMO

We investigate the shape of near-Earth asteroid (101955) Bennu by constructing a high-resolution (20 cm) global digital terrain model from laser altimeter data. By modeling the northern and southern hemispheres separately, we find that longitudinal ridges previously identified in the north extend into the south but are obscured there by surface material. In the south, more numerous large boulders effectively retain surface materials and imply a higher average strength at depth to support them. The north has fewer large boulders and more evidence of boulder dynamics (toppling and downslope movement) and surface flow. These factors result in Bennu's southern hemisphere being rounder and smoother, whereas its northern hemisphere has higher slopes and a less regular shape. We infer an originally asymmetric distribution of large boulders followed by a partial disruption, leading to wedge formation in Bennu's history.

17.
Science ; 370(6517)2020 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-33033157

RESUMO

Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. Here we present multispectral images (0.44 to 0.89 micrometers) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet region (i.e., become bluer at shorter wavelengths), then brighten in the visible to near-infrared region, leading to Bennu's moderately blue average color. Craters indicate that the time scale of these color changes is ~105 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.

18.
Artigo em Inglês | MEDLINE | ID: mdl-32936334

RESUMO

PURPOSE: Age at primary dislocation, recurrence, and glenoid bone loss are associated with development of osteoarthritis (OA). However, an overview of OA following traumatic anterior shoulder instability is lacking and it is unclear to what degree type of surgery is associated with development of OA in comparison to non-operative treatment. The aim of this study was to determine the degree of OA at long-term follow-up after non-operative and operative treatments for patients with anterior shoulder instability. Surgery is indicated when patients experience recurrence and this is associated with OA; therefore, it was hypothesized that shoulders show a higher proportion or degree of OA following operative treatment compared to non-operative treatment. METHODS: A literature search was performed in the PubMed/Medline, EMBASE, and Cochrane databases. Articles reporting the degree of OA that was assessed with the Samilson-Prieto or Buscayret OA classification method after non-operative and operative treatment for anterior shoulder instability with a minimum of 5 years follow-up were included. RESULTS: Thirty-six articles met the eligibility criteria of which 1 reported the degree of OA for non-operative treatment and 35 reported the degree of OA for 9 different operative procedures. A total of 1832 patients (1854 shoulders) were included. OA proportions of non-operative and operative treatments are similar at any point of follow-up. The Latarjet procedure showed a lower degree of OA compared to non-operative treatment and the other operative procedures, except for the Bristow procedure and Rockwood capsular shift. The meta-analyses showed comparable development of OA over time among the treatment options. An increase in OA proportion was observed when comparing the injured to the contralateral shoulder. However, a difference between the operative subgroups was observed in neither analysis. CONCLUSION: Non-operative and operative treatments show similar OA proportions at any point of follow-up. The hypothesis that shoulders showed a higher proportion or degree of OA following operative treatment compared to non-operative treatment is not supported by the data. Operative treatment according to the Latarjet procedure results in a lower degree of OA compared to other treatments, including non-operative treatment. LEVEL OF EVIDENCE: IV.

19.
Clin Neurophysiol Pract ; 5: 157-164, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32939420

RESUMO

Objective: It is unclear why specific individuals incur chronic symptoms following a concussion. This exploratory research aims to identify and characterize any neurophysiological differences that may exist in motor cortex function in post-concussion syndrome (PCS). Methods: Fifteen adults with PCS and 13 healthy, non-injured adults were tested. All participants completed symptom questionnaires, and transcranial magnetic stimulation (TMS) was used to measure intracortical and transcallosal excitability and inhibition in the dominant motor cortex. Results: Cortical silent period (p = 0.02, g = 0.96) and ipsilateral silent period (p = 0.04, g = 0.78) were shorter in the PCS group compared to the control group which may reflect reduced GABA-mediated inhibition in PCS. Furthermore, increased corticomotor excitability was observed in the left hemisphere but not the right hemisphere. Conclusions: These data suggest that persistent neurophysiological differences are present in those with PCS. The exact contributing factors to such changes remain to be investigated by future studies. Significance: This study provides novel evidence of lasting neurophysiological changes in PCS.

20.
JSES Int ; 4(3): 606-611, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32939494

RESUMO

Background: To aid the interpretation of clinical outcome scores, it is important to determine the measurement properties. The aim of this study was to establish the minimal clinically important difference (MCID) and substantial clinical benefit (SCB) for the Constant-Murley score and Disabilities of the Arm, Shoulder and Hand score in patients with long-lasting rotator cuff calcific tendinitis treated with high-energy extracorporeal shockwave therapy and ultrasound guided needling. The secondary purpose was to assess the responsiveness of both questionnaires and to identify variables associated with achieving the MCID and SCB. Methods: A prospective cohort of 80 patients with rotator cuff calcific tendinitis was analyzed. Two anchor-based methods were used to calculate the MCID and SCB. Effect sizes and standardized response means were calculated to assess the responsiveness. Additional univariate logistic regression analyses were performed to identify factors associated with the achievement of the MCID and SCB. Results: For the Constant-Murley score, we found an MCID and SCB of 9.8 and 19.9, respectively, based on the mean change method and 5.5 and 10.5, respectively, based on receiver operating characteristic analysis. For the Disabilities of the Arm, Shoulder and Hand score, we found an MCID and SCB of -8.2 and -19.6, respectively, with the former and -11.7 and -12.5, respectively, with the latter. The responsiveness of both outcome measures was good, with large effect sizes and standardized response means. The radiographic resorption after 6 weeks and after 6 months appeared to be the most important positive predictor for achieving the MCID and SCB after 6 months. Conclusion: This study established the MCID, SCB, and responsiveness for patients with long-lasting rotator cuff calcific tendinitis who were treated with minimally invasive treatment options. With this information, physicians can distinguish between a statistically significant difference and a clinically relevant benefit. Successful radiographic resorption after 6 weeks and after 6 months was associated with achieving clinically significant improvement after treatment.

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