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1.
JHEP Rep ; 6(7): 101066, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39022387

RESUMO

Background & Aims: Patients with nonalcoholic fatty liver disease (NAFLD)/metabolic dysfunction-associated steatotic liver disease (MASLD) face a multifaceted disease burden which includes impaired health-related quality of life (HRQL) and potential stigmatization. We aimed to assess the burden of liver disease in patients with NAFLD and the relationship between experience of stigma and HRQL. Methods: Members of the Global NASH Council created a survey about disease burden in NAFLD. Participants completed a 35-item questionnaire to assess liver disease burden (LDB) (seven domains), the 36-item CLDQ-NASH (six domains) survey to assess HRQL and reported their experience with stigmatization and discrimination. Results: A total of 2,117 patients with NAFLD from 24 countries completed the LDB survey (48% Middle East and North Africa, 18% Europe, 16% USA, 18% Asia) and 778 competed CLDQ-NASH. Of the study group, 9% reported stigma due to NAFLD and 26% due to obesity. Participants who reported stigmatization due to NAFLD had substantially lower CLDQ-NASH scores (all p <0.0001). In multivariate analyses, experience with stigmatization or discrimination due to NAFLD was the strongest independent predictor of lower HRQL scores (beta from -5% to -8% of score range size, p <0.02). Experience with stigmatization due to obesity was associated with lower Activity, Emotional Health, Fatigue, and Worry domain scores, and being uncomfortable with the term "fatty liver disease" with lower Emotional Health scores (all p <0.05). In addition to stigma, the greatest disease burden as assessed by LDB was related to patients' self-blame for their liver disease. Conclusions: Stigmatization of patients with NAFLD, whether it is caused by obesity or NAFLD, is strongly and independently associated with a substantial impairment of their HRQL. Self-blame is an important part of disease burden among patients with NAFLD. Impact and implications: Patients with nonalcoholic fatty liver disease (NAFLD), recently renamed metabolic dysfunction-associated steatotic liver disease (MASLD), may experience impaired health-related quality of life and stigmatization. Using a specifically designed survey, we found that stigmatization of patients with NAFLD, whether it is caused by obesity or the liver disease per se, is strongly and independently associated with a substantial impairment of their quality of life. Physicians treating patients with NAFLD should be aware of the profound implications of stigma, the high prevalence of self-blame in the context of this disease burden, and that providers' perception may not adequately reflect patients' perspective and experience with the disease.

2.
Eur Cardiol ; 19: e06, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38983581

RESUMO

The terms non-alcoholic fatty liver disease and non-alcoholic steatohepatitis have some limitations as they use exclusionary confounder terms and the use of potentially stigmatising language. Recently, a study with content experts and patients has been set to change this nomenclature. The term chosen to replace non-alcoholic fatty liver disease was metabolic dysfunction-associated steatotic liver disease (MASLD), which avoids stigmatising and helps improve awareness and patient identification. MASLD is the most common cause of chronic liver disease with an increasing prevalence, accounting for 25% of the global population. It is considered the hepatic manifestation of the metabolic syndrome with lifestyle playing a fundamental role in its physiopathology. Diet change and physical activity are the cornerstones of treatment, encompassing weight loss and healthier behaviours and a holistic approach. In Europe, there is no approved drug for MASLD to date and there is a substantial unmet medical need for effective treatments for patients with MASLD. This review not only provides an update on advances in evidence for nutrition and physical activity interventions but also explores the different therapeutic options that are being investigated and whose development focuses on the restitution of metabolic derangements and halting inflammatory and fibrogenic pathways.

3.
J Clin Med ; 13(11)2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38893027

RESUMO

Background: The purpose of this investigation was to determine the elastic characteristics of the common carotid artery (CCA) during endurance exercise at 3 different intensities. Methods: Twenty young healthy participants (10 males and 10 females) participated in this quasi-experimental cross-sectional study. Participants were tested in two sessions: (1) we took resting measurements of the elastic characteristics of the CCA and performed a cardiopulmonary exercise test (CPET) on a cycle ergometer to determine submaximal exercise intensities, and we conducted (2) measurements of the elastic characteristics of the CCA while exercising in a cycle ergometer at 3 intensities based on blood lactate levels of low (<2 mmol/L), moderate (2-4 mmol/L), and high (>4 mmol/L). Beta stiffness was calculated using CCA diameters during systole and diastole, measured with high-definition ultrasound imaging, and CCA systolic and diastolic pressures were measured via applanation tonometry. Results: Overall, there were no differences between males and females in terms of any of the studied variables (p > 0.05). In addition, no significant changes were found in the CCA beta stiffness and vessel diameter (p > 0.05) between exercise intensities. There was a significant exercise intensity effect on CCA systolic pressure (p < 0.05), but not on CCA diastolic pressure (p > 0.05). Conclusions: The biomechanical characteristics of the CCA, determined via compliance and beta-stiffness, do not change during cyclical aerobic exercise, regardless of exercise intensity.

4.
J Gastrointestin Liver Dis ; 33(2): 234-244, 2024 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-38944876

RESUMO

BACKGROUND AND AIMS: Chronic liver diseases belong to the most common diseases worldwide and are associated with increased morbidity and mortality. Although more than one in three adults are estimated to have metabolic dysfunction-associated steatotic liver disease (MASLD), awareness of this condition is low amongst the general public, health care professionals and policy makers. However, meaningful knowledge transfer is essential for raising awareness and improving prevention and treatment. This study set out to investigate the use of the major internet search engine to understand how knowledge transfer has evolved by analyzing liver-related searches trends. METHODS: We investigated Google search trends by measuring the number of hits relating to liver diseases between 2004 and 2021 in seven languages and European countries but also worldwide. All analyses were performed in R using the R Google trends package gtrendsR. RESULTS: We found that interest in MASLD [formerly non-alcoholic fatty liver disease (NAFLD)] has generally increased over time, but that interest in metabolic associated steatohepatitis (MASH) - the most severe form of MASLD - has decreased. Interest in viral hepatitis C has decreased, whereas the number of queries regarding viral hepatitis B have been stable but dominated by interest in vaccination for it. Recent medical developments (in viral hepatitis) did not lead to a noticeable change in overall search behavior. Users preferred searching using their native language and less complex medical terms and acronyms (e.g., fatty liver instead of NAFLD). CONCLUSIONS: In the last two decades, Google search trends have followed the general development in the field of hepatology. Searches were dominated by non-experts and are not being rapidly influenced by novel scientific developments. Also, users preferred search terms in their native languages rather than English and tended to avoid complex medical search terms. Awareness and communication strategies around MASLD should consider these preferences when addressing the general public.


Assuntos
Ferramenta de Busca , Humanos , Europa (Continente)/epidemiologia , Ferramenta de Busca/tendências , Hepatopatias/epidemiologia , Internet , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Comportamento de Busca de Informação , Informação de Saúde ao Consumidor/tendências
5.
Food Chem ; 456: 140004, 2024 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-38870813

RESUMO

Natural toxins, such as mycotoxins and cyanotoxins, can contaminate food and feed, leading to toxicity in humans and animals. This study focused on using nine magnetic nanostructured agents to remove the main types of toxins. Initially, the efficacy of these materials was evaluated in water solutions, revealing that composites with sizes below 3 mm, containing magnetite, activated carbon, esterified pectin, and sodium alginate, removed up to 90% of mycotoxins and cyanotoxins with an adsorption of 873 ng/g. The application of the nanostructures was then assessed in beer, milk, Distillers Dried Grains with Solubles and water contaminated with cyanobacteria. The presence of matrix slightly decreases the adsorption capacity for some toxins. The maximum toxin removal capacity was calculated with cyanotoxins, composites achieved a removal of up to 0.12 mg/g, while nanocomposites (15 µm) reached 36.6 mg/g. Therefore, these findings point out the potential for using nanotechnology in addressing natural toxins contamination.


Assuntos
Contaminação de Alimentos , Micotoxinas , Nanoestruturas , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Micotoxinas/química , Micotoxinas/análise , Adsorção , Nanoestruturas/química , Animais , Cadeia Alimentar , Cerveja/análise , Leite/química , Toxinas Bacterianas/química , Cianobactérias/química , Microcistinas/química , Microcistinas/análise
6.
Artigo em Inglês | MEDLINE | ID: mdl-38898570

RESUMO

Backgrounds/Aims: Thirty percent of liver grafts in donors after brain death (DBD) in Spain are rejected by procurement surgeons owing to marginal graft quality. Poor donor indocyanine green (ICG) clearance has been associated with graft discard and malfunction. This study aimed to internally and externally validate the predictive value of ICG-plasma disappearance rate (ICG-PDR) to reject grafts before donation and set a cut-off to avoid missing any potential effective donors. Methods: Between March 2017 and August 2023, ICG clearance test was performed immediately before procurement in 71 DBD. The surgeon was blinded to test results. Univariate and multivariate analyses were performed to detect independent predictors of graft discard. Discrimination and calibration of predictors were assessed and a cut-off with 100% specificity was set. External validation was performed on 17 donors evaluated by three other transplantation teams. Results: In the training cohort, 30 of 71 grafts were discarded for transplantation. ICG-PDR was the only donor variable independently associated with graft discard. The area under receiver operating characteristic curve for ICG-PDR was 0.875 (95% confidence interval: 0.768-0.947) and good calibration was observed. Below a PDR of 13.5%/min, no graft was accepted for transplantation. These results were successfully validated using the external cohort of donors. Conclusions: ICG clearance test performed in DBD was internally and externally validated to predict liver graft discard. It could be used as a screening tool before donation to avoid unnecessary costs of travel and human resources.

7.
Hepatol Int ; 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38900410

RESUMO

BACKGROUND AND AIMS: Healthy weight (lean) patients with metabolic dysfunction-associated fatty liver disease (MAFLD) have a more favorable metabolic and histological profile in cross-sectional studies compared with their non-lean counterparts. Paradoxically, they also have higher overall mortality. The underpinning pathophysiology of this paradox is not understood. Telomere attrition is associated with increased mortality in various diseases. METHODS: We investigated the role of telomere length in the pathogenesis of lean MAFLD in cohorts with biopsy-proven MAFLD (n = 303). We measured serum malondialdehyde (MDA) levels and hepatic 8-hydroxydeoxyguanosine (8-OHdG) and 4-hydroxy-2-nonenal (4-HNE) expression (reactive oxygen species (ROS) markers), growth/differentiation factor-15 (GDF-15) and tested the effect of H2O2 on telomere length and activity in hepatocyte cell lines. The association between leukocyte telomere length and mortality was examined. RESULTS: Telomere length was significantly lower in patients with lean MAFLD (p < 0.001). They also demonstrated an increase in ROS levels and decreases in GDF-15. H2O2 induced telomere shortening and reducing telomere activity in hepatocyte cell lines. We subsequently confirmed that telomere length shortening at baseline is associated with increased hazards of all-cause mortality; the deleterious effect was more profound in lean people. CONCLUSION: Differences in telomere length in part explain the increased mortality of lean compared to non-lean patients with MAFLD. The effect is in part mediated through ROS activation and provide opportunities for therapy.

8.
Artigo em Inglês | MEDLINE | ID: mdl-38894596

RESUMO

AIM: We aimed to assess the role of FGF21 in metabolic dysfunction-associated steatotic liver disease (MASLD) at a multi-scale level. METHODS: We used human MASLD pathology samples for FGF21 gene expression analyses (qPCR and RNAseq), serum to measure circulating FGF21 levels and DNA for genotyping the FGF21 rs838133 variant in both estimation and validation cohorts. A hepatocyte-derived cell line was exposed to free fatty acids at different timepoints. Finally, C57BL/6J mice were fed a high-fat and choline-deficient diet (CDA-HFD) for 16 weeks to assess hepatic FGF21 protein expression and FGF21 levels by ELISA. RESULTS: A significant upregulation in FGF21 mRNA expression was observed in the liver analysed by both qPCR (fold change 5.32 ± 5.25 vs. 0.59 ± 0.66; p = 0.017) and RNA-Seq (3.5 fold; FDR: 0.006; p < 0.0001) in MASLD patients vs. controls. Circulating levels of FGF21 were increased in patients with steatohepatitis vs. bland steatosis (386.6 ± 328.9 vs. 297.9 ± 231.5 pg/mL; p = 0.009). Besides, sex, age, A-allele from FGF21, GG genotype from PNPLA3, ALT, type 2 diabetes mellitus and BMI were independently associated with MASH and significant fibrosis in both estimation and validation cohorts. In vitro exposure of Huh7.5 cells to high concentrations of free fatty acids (FFAs) resulted in overexpression of FGF21 (p < 0.001). Finally, Circulating FGF21 levels and hepatic FGF21 expression were found to be significantly increased (p < 0.001) in animals under CDA-HFD. CONCLUSIONS: Hepatic and circulating FGF21 expression was increased in MASH patients, in Huh7.5 cells under FFAs and in CDA-HFD animals. The A-allele from the rs838133 variant was also associated with an increased risk of steatohepatitis and significant and advanced fibrosis in MASLD patients.

9.
Org Biomol Chem ; 22(26): 5289-5295, 2024 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-38881431

RESUMO

A series of linked-type 1,5-disubstituted tetrazoles (1,5-DS-Ts) were synthesised via an isocyanide-based multicomponent reaction (IMCR) and used as synthetic platforms to access bound-type polyheterocycles containing an epoxyisoindol-1(6H)-one scaffold under green conditions. This rapid sonochemical synthetic strategy includes a double domino process using an orthogonal heterocyclic input in the Ugi-azide (UA) reaction. DFT calculations and NBO analysis were performed to understand the pseudopericyclic reaction involved in the 1,5-electrocyclization of the UA mechanism.

11.
Endocrinol Diabetes Nutr (Engl Ed) ; 71(4): 177-180, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38735679

RESUMO

Thyrotoxicosis is the clinical condition resulting from an excess of thyroid hormones for any reason. The main causes are Graves-Basedow disease, toxic multinodular goitre and toxic adenoma. The medical treatment to control thyroid function includes antithyroid drugs, beta blockers, iodine solutions, corticosteroids and cholestyramine. Although therapeutic plasma exchange is not generally part of the therapy, it is an alternative as a preliminary stage before the definitive treatment. This procedure makes it possible to eliminate T4, T3, TSI, cytokines and amiodarone. In most cases, more than one cycle is necessary, either daily or every three days, until clinical improvement is observed. The effect on thyrotoxicosis is temporary, with an approximate duration of 24-48h. This approach has been proposed as a safe and effective alternative when the medical treatment is contraindicated or not effective, and when there is multiple organ failure or emergency surgery is required.


Assuntos
Troca Plasmática , Tireotoxicose , Humanos , Tireotoxicose/terapia , Feminino , Pessoa de Meia-Idade , Masculino
12.
PLoS One ; 19(5): e0300362, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38709751

RESUMO

BACKGROUND: It is unclear what biopsychosocial factors influence the impact of NAFLD on health-related quality of life (HRQoL), and if these factors are equally important predictors between different nationalities. METHODS: HRQoL (CLDQ) was measured in both Southern European (Spain, n = 513) and Northern European (United Kingdom -UK-, n = 224) cohorts of patients with NAFLD in this cross-sectional study. For each cohort, participant data were recorded on histological grade of steatohepatitis, stage of fibrosis and biopsychosocial variables. Regression analysis was used to explore which of these variables predicted HRQoL. Moderated mediation models were conducted using SPSS PROCESS v3.5 macro. RESULTS: Participants with severe fibrosis reported more fatigue, systemic symptoms and worry, and lower HRQoL than those with none/mild fibrosis, regardless of place of origin. In addition, body mass index (BMI) and gender were found to be significant predictors of HRQoL in both Spanish and UK participants. Female gender was associated with worse emotional function, higher BMI and more fatigue, which predicted lower participants' HRQoL. UK participants showed more systemic symptoms and worry than Spanish participants, regardless of liver severity. The negative effects of gender on HRQoL through emotional function, BMI and fatigue were reported to a greater degree in UK than in Spanish participants. CONCLUSIONS: UK participants showed a greater impairment in HRQoL as compared to Spanish participants. Higher fibrosis stage predicted lower HRQoL, mainly in the Spanish cohort. Factors such as female gender or higher BMI contributed to the impact on HRQoL in both cohorts of patients and should be considered in future multinational intervention studies in NAFLD.


Assuntos
Comparação Transcultural , Hepatopatia Gordurosa não Alcoólica , Qualidade de Vida , Humanos , Hepatopatia Gordurosa não Alcoólica/psicologia , Masculino , Reino Unido/epidemiologia , Feminino , Espanha/epidemiologia , Pessoa de Meia-Idade , Estudos Transversais , Adulto , Índice de Massa Corporal , Fadiga/psicologia
13.
Eur Cardiol ; 19: e03, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38807856

RESUMO

The global prevalence of non-alcoholic fatty liver disease (NAFLD) is nearly 25% and is increasing rapidly. The spectrum of liver damage in NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis, characterised by the presence of lobular inflammation and hepatocyte ballooning degeneration, with or without fibrosis, which can further develop into cirrhosis and hepatocellular carcinoma. Not only is NAFLD a progressive liver disease, but numerous pieces of evidence also point to extrahepatic consequences. Accumulating evidence suggests that patients with NAFLD are also at increased risk of cardiovascular disease (CVD); in fact, CVDs are the most common cause of mortality in patients with NAFLD. Obesity, type 2 diabetes and higher levels of LDL are common risk factors in both NAFLD and CVD; however, how NAFLD affects the development and progression of CVD remains elusive. In this review, we comprehensively summarise current data on the key extrahepatic manifestations of NAFLD, emphasising the possible link between NAFLD and CVD, including the role of proprotein convertase substilisin/kenin type 9, extracellular vesicles, microbiota, and genetic factors.

14.
Rev Esp Enferm Dig ; 2024 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-38767045

RESUMO

AIM: To determine the impact of liver fibrosis on the prognosis of COVID and the liver injury associated with the infection. METHODS: Retrospective multicenter study including 575 patients requiring admission for COVID-19 between January and June 2020. FIB-4 was calculated within 6 months prior to infection and at 6 months post-infection. RESULTS: Baseline FIB-4 was increased in patients who died (1.91±0.95 vs. 1.43±0.85; p<0.001). In addition, the 17.1% (32/187) of patients with baseline FIB-4<1.45 died versus 52.9% (9/17) if FIB-4>3.25 (p<0.001). In the adjusted multivariate analysis, baseline FIB-4 (OR 1.61 (95%CI 1.19-2.18); p=0.002) was independently associated with mortality. Parameters associated with liver injury, including AST (28±10 vs. 45±56IU/L; p<0.001) and ALT (20±12 vs. 38±48IU/L; p<0.001) were significantly higher at admission compared to baseline. Also, FIB-4 was increased from baseline to the time of admission (1.53±0.88 vs. 2.55±1.91; p<0.001), and up to 6.9% (10/145) of patients with FIB-4<1.45 at admission died versus 47.5% if FIB-4>3.25 (58/122) (p<0.001). In the adjusted multivariate analysis, FIB-4 at admission (OR 1.14 (95%CI 1.03-1.27); p=0.015) was independently associated with mortality. Also, AST (42±38 vs. 22±17IU/L; p<0.001) and ALT (40±50 vs. 20±19 IU/L; p<0.001) were significantly reduced at 6 months after the resolution of infection. Accordingly, FIB-4 decreased significantly (2.12±1.25 vs. 1.32±0.57; p<0.001) six months after the infection. CONCLUSION: Increased FIB-4, either at baseline or at the time of admission, was related to the severity and mortality related to SARS-CoV-2 infection. However, the liver damage expressed by elevated transaminases and FIB-4 was reversible in most of patients.

15.
Expert Rev Gastroenterol Hepatol ; 18(6): 239-256, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38785070

RESUMO

INTRODUCTION: Classically, clinical practice guidelines and expert recommendations have focused on the management of decompensated cirrhotic patients, so we focused this review on improving care for compensated cirrhotic patients who are followed up in outpatient clinics. AREAS COVERED: We reviewed the current methods for establishing liver function, the diagnosis and management of advanced chronic liver disease and clinically significant portal hypertension as well as the prevention of its complications, with special attention to covert hepatic encephalopathy, we also paid attention to the extrahepatic complications of cirrhosis and the palliative care. All this from the perspective of evidence-based medicine and trying to empower precision medicine. The literature search was undertaken by PubMed with 'cirrhosis,' 'advanced chronic liver disease,' 'liver function,' 'portal hypertension,' 'covert hepatic encephalopathy,' 'minimal hepatic encephalopathy,' 'palliative care' as MeSH terms. EXPERT OPINION: We must offer compensated cirrhotic patients specific care and measures to prevent the progression of the disease and the appearance of its complications beyond the calculation of liver function and imaging screening for hepatocellular carcinoma that we perform every six months. Entities that have typically received little attention, such as covert hepatic encephalopathy, extrahepatic complications and symptoms of cirrhosis, and palliative care, must come to the spotlight.


Assuntos
Encefalopatia Hepática , Cirrose Hepática , Cuidados Paliativos , Humanos , Cirrose Hepática/complicações , Cirrose Hepática/terapia , Encefalopatia Hepática/terapia , Encefalopatia Hepática/etiologia , Encefalopatia Hepática/diagnóstico , Hipertensão Portal/terapia , Hipertensão Portal/etiologia , Hipertensão Portal/diagnóstico , Progressão da Doença , Testes de Função Hepática
16.
Protoplasma ; 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38802622

RESUMO

Hydrogen peroxide (H2O2) is naturally produced by plant cells during normal development and serves as a messenger that regulates cell metabolism. Despite its importance, the relationship between hydrogen peroxide and the target of rapamycin (TOR) pathway, as well as its impact on cell division, has been poorly analyzed. In this study, we explore the interaction of H2O2 with TOR, a serine/threonine protein kinase that plays a central role in controlling cell growth, size, and metabolism in Arabidopsis thaliana. By applying two concentrations of H2O2 exogenously (0.5 and 1 mM), we could correlate developmental traits, such as primary root growth, lateral root formation, and fresh weight, with the expression of the cell cycle gene CYCB1;1, as well as TOR expression. When assessing the expression of the ribosome biogenesis-related gene RPS27B, an increase of 94.34% was noted following exposure to 1 mM H2O2 treatment. This increase was suppressed by the TOR inhibitor torin 2. The elimination of H2O2 accumulation with ascorbic acid (AA) resulted in decreased cell division as well as TOR expression. The potential molecular mechanisms associated with the effects of H2O2 on the cell cycle and TOR expression in roots are discussed in the context of the results.

18.
Science ; 384(6691): 87-93, 2024 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-38574149

RESUMO

Agricultural simplification continues to expand at the expense of more diverse forms of agriculture. This simplification, for example, in the form of intensively managed monocultures, poses a risk to keeping the world within safe and just Earth system boundaries. Here, we estimated how agricultural diversification simultaneously affects social and environmental outcomes. Drawing from 24 studies in 11 countries across 2655 farms, we show how five diversification strategies focusing on livestock, crops, soils, noncrop plantings, and water conservation benefit social (e.g., human well-being, yields, and food security) and environmental (e.g., biodiversity, ecosystem services, and reduced environmental externalities) outcomes. We found that applying multiple diversification strategies creates more positive outcomes than individual management strategies alone. To realize these benefits, well-designed policies are needed to incentivize the adoption of multiple diversification strategies in unison.


Assuntos
Agricultura , Biodiversidade , Conservação dos Recursos Naturais , Ecossistema , Humanos , Fazendas , Solo
19.
Biomimetics (Basel) ; 9(4)2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38667251

RESUMO

The use of metamaterials is a good alternative when looking for structures that can withstand compression forces without increasing their weight. In this sense, using nature as a reference can be an appropriate option to design this type of material. Therefore, in this work, a comparative study of a selection of eight representative models of a wide variety of existing solutions, both bioinspired and proposed by various researchers, is presented. These models have been manufactured using stereolithography (SLA) printing, which allows complex geometries to be obtained in a simple way that would be more complicated to achieve by other procedures. Additionally, the manufacturing cost of each model has been determined. The compression tests of the different models have made it possible to evaluate the breaking force and its corresponding deformation. Likewise, a finite element analysis of the manufactured models has been carried out to simulate their behavior under compression, achieving results very similar to those obtained in the experimental tests. In this way, it has been concluded that, among the three-dimensional patterns, the structure called "3D auxetic" is the one that supports the greatest breaking force due to the topographic characteristics of its bar structure. Similarly, among the two-dimensional patterns, the structure called "Auxetic 1", with a topography based on curves, is capable of supporting the greatest deformation in the compression direction before breaking. Moreover, the highest resistance-force-to-cost ratio has been obtained with a "3D auxetic" structure.

20.
Int J Exerc Sci ; 17(3): 199-211, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38665687

RESUMO

The COVID-19 pandemic affected many aspects of everyday life including school, fitness regimens, and social interactions. The purpose of this study is to understand how COVID-19 restrictions affect the cardiovascular and mental health of Doctor of Physical Therapy (DPT) students as they progressed through the program. Data collection occurred in 16 DPT students (8F:8M, 24±3 years) over a total of 3 visits from 2020 to 2022, during high, moderate, and low COVID-19 restrictions. Outcome measures included VO2max, Venous Occlusion Plethysmography (VOP), %fat mass measured via DEXA, Perceived Stress Scale (PSS) and International Physical Activity Questionnaire (IPAQ). A RM-ANOVA with pairwise comparisons was utilized. Significance was set prior at an α level of 0.05. There was a significant increase (p<0.05) from visit 1 to 2 in VO2max, VOP baseline, BMI, and METs. There was a significant decrease (p<0.05) from visit 2 to 3 in VO2max. Finally, a significant increase in visit 3 was seen from visit 2 in VOP peak. Overall, there was no significant difference observed for PSS and %fat mass (p>0.05). Between high and moderate restrictions, there was an increase in VO2max, VOP baseline, and METs. However, between moderate and low restrictions, only VOP Peak increased. This could be attributed to gyms being closed and limiting the type of physical activity a person could do to exercises like running or walking. When restrictions were lifted, traveling to and from classes, traveling to gyms, and socializing all increased, limiting the time for physical activity.

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