Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 384
Filtrar
1.
Public Health Ethics ; 17(1-2): 67-79, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39005526

RESUMO

In late March 2020 in response to the COVID-19 pandemic, Australia introduced mandatory 14-day supervised quarantine at hotels and other designated facilities for all international arrivals. From July 2020, most states and territories introduced a fixed charge for quarantine of up to $3220 per adult. The introduction of the fee was rationalised on the basis that Australians had been allowed sufficient time to return and there was a need to recover some of the cost associated with administering the program. Drawing on an empirical study of 58 returned Australian citizens and residents quarantined between March 2020 and January 2021, this paper aims to explore how people experienced paying for hotel quarantine, particularly with respect to fairness and relatedly, the principle of reciprocity. Reciprocity requires that the state has an obligation to assist individuals in discharging their duty to comply with public health measures and avoid disproportionate burdens accruing to populations or individuals. Though participants had varying opinions on whether they thought it fair to be charged for their quarantine, for many, the fee constituted a significant burden and source of stress. Given the undertaking of quarantine is primarily for the benefit of the public good, we argue the financial cost imposed on individuals does not meet the demands of reciprocity. It is imperative that future quarantine and isolation arrangements consider seriously the need to minimise burdens of individuals subject to such measures, and that fees do not become a new norm in public health and infectious disease control.

2.
New Phytol ; 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38952269

RESUMO

The diversity of plant-pollinator interactions is grounded in floral resources, with nectar considered one of the main floral rewards plants produce for pollinators. However, a global evaluation of the number of animal-pollinated nectar-producing angiosperms and their distribution world-wide remains elusive. We compiled a thorough database encompassing 7621 plant species from 322 families to estimate the number and proportion of nectar-producing angiosperms reliant on animal pollination. Through extensive sampling of plant communities, we also explored the interplay between nectar production, floral resource diversity, latitudinal and elevational gradients, contemporary climate, and environmental characteristics. Roughly 223 308 animal-pollinated angiosperms are nectar-producing, accounting for 74.4% of biotic-pollinated species. Global distribution patterns of nectar-producing plants reveal a distinct trend along latitudinal and altitudinal gradients, with increased proportions of plants producing nectar in high latitudes and altitudes. Conversely, tropical communities in warm and moist climates exhibit greater floral resource diversity and a lower proportion of nectar-producing plants. These findings suggest that ecological trends driven by climate have fostered the diversification of floral resources in warmer and less seasonal climates, reducing the proportion of solely nectar-producing plants. Our study provides a baseline for understanding plant-pollinator relationships, plant diversification, and the distribution of plant traits.

3.
Am J Clin Pathol ; 2024 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-39001688

RESUMO

OBJECTIVES: We sought to evaluate the analytical performance of the Alinity m system (Abbott Molecular) and to compare the clinical performance of HIV-1 assays on the Alinity m and m2000 RealTime platforms (Abbott Molecular). METHODS: The sensitivity, precision, and accuracy of the Alinity m instrument were determined using a panel of standard samples (n = 46). The carryover effect was assessed by analyzing HIV-negative clinical samples (n = 20). Clinical performance of the Alinity m and m2000 RealTime platforms was compared using surplus HIV-positive patient plasma samples (n = 39). RESULTS: The Alinity m HIV-1 assay demonstrated 100% sensitivity, a high precision (coefficient of variation (s/x̄) × 100 ≤1.5% [SD ≤ 0.05] logarithm to base 10 [log10] copies/mL), and partial accuracy over the quantification range. Analysis of clinical samples suggested that the Alinity m HIV-1 assay does not cause carryover effect and produced a mean bias of 0.209 log10 copies/mL (95% CI, 0.153-0.265) compared with the m2000 RealTime System. CONCLUSIONS: The Alinity m instrument's performance correlated to that of the m2000 RealTime platform and showed excellent sensitivity, precision, and accuracy, despite producing overquantification not clinically relevant for disease management. Furthermore, use of the Alinity m platform can reduce turnaround time.

4.
Proc Natl Acad Sci U S A ; 121(29): e2317977121, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38990941

RESUMO

In a recent characterization of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variability present in 30 diagnostic samples from patients of the first COVID-19 pandemic wave, 41 amino acid substitutions were documented in the RNA-dependent RNA polymerase (RdRp) nsp12. Eight substitutions were selected in this work to determine whether they had an impact on the RdRp activity of the SARS-CoV-2 nsp12-nsp8-nsp7 replication complex. Three of these substitutions were found around the polymerase central cavity, in the template entry channel (D499G and M668V), and within the motif B (V560A), and they showed polymerization rates similar to the wild type RdRp. The remaining five mutations (P323L, L372F, L372P, V373A, and L527H) were placed near the nsp12-nsp8F contact surface; residues L372, V373, and L527 participated in a large hydrophobic cluster involving contacts between two helices in the nsp12 fingers and the long α-helix of nsp8F. The presence of any of these five amino acid substitutions resulted in important alterations in the RNA polymerization activity. Comparative primer elongation assays showed different behavior depending on the hydrophobicity of their side chains. The substitution of L by the bulkier F side chain at position 372 slightly promoted RdRp activity. However, this activity was dramatically reduced with the L372P, and L527H mutations, and to a lesser extent with V373A, all of which weaken the hydrophobic interactions within the cluster. Additional mutations, specifically designed to disrupt the nsp12-nsp8F interactions (nsp12-V330S, nsp12-V341S, and nsp8-R111A/D112A), also resulted in an impaired RdRp activity, further illustrating the importance of this contact interface in the regulation of RNA synthesis.


Assuntos
Mutação Puntual , RNA Viral , SARS-CoV-2 , Proteínas não Estruturais Virais , SARS-CoV-2/genética , SARS-CoV-2/metabolismo , Proteínas não Estruturais Virais/genética , Proteínas não Estruturais Virais/metabolismo , Proteínas não Estruturais Virais/química , RNA Viral/genética , RNA Viral/metabolismo , Humanos , RNA-Polimerase RNA-Dependente de Coronavírus/genética , RNA-Polimerase RNA-Dependente de Coronavírus/metabolismo , Polimerização , COVID-19/virologia , Substituição de Aminoácidos , RNA Polimerase Dependente de RNA/genética , RNA Polimerase Dependente de RNA/metabolismo , Modelos Moleculares
5.
Forensic Sci Res ; 9(2): owad046, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38903907

RESUMO

Several studies have evaluated the parameters of normality of the sella turcica (ST), which is important to face different craniofacial syndromes that may affect this structure. Therefore, this research summarized the scientific evidence on the role of ST in the sex estimation of non-syndromic individuals. The research protocol was registered (Prospective International Registry of Systematic Reviews # CRD42021256469), followed by an electronic search in six databases (PubMed, LILACS, Web of Science, Scopus, EMBASE, and LIVIVO) and gray literature (Google Scholar and OpenGrey). Meta-analysis of linear (width, length, height, and diameter) and volumetric measurements, in addition to an assessment of risk of bias (RoB) and certainty of evidence, were performed. After the screening of 986 articles, 13 were evaluated by meta-analysis (1 307 males and 1 231 females). In subgroup analysis, females had lower values for width (lateral radiograph; -0.67 mm; P = 0.040), length (computed tomography; -0.23 mm; P = 0.020), and diameter (computed tomography; -0.27 mm; P < 0.001) compared to males. There was no statistically significant difference regarding height (P = 0.95), area (P = 0.72), and volume (P = 0.21). Most studies exhibited moderate RoB, and the certainty of evidence of the outcomes was very low. In this review, significant differences were observed between the sexes for the length and diameter of the ST; however, the heterogeneity of the studies must be considered. Key points: Studies from different geographic regions evaluated the morphology of ST according to sex and showed this anatomical structure as an important indicator of dimorphism.Meta-analysis showed shorter ST length and diameter in women.Subgroup analysis found lower ST width in women based on lateral skull radiographs.Subgroup analysis found smaller lengths and diameters in women based on CT scans.

6.
Carbohydr Polym ; 340: 122317, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-38858030

RESUMO

Brown macroalgae synthesize large amounts of fucoidans, sulfated fucose-containing polysaccharides, in the ocean. Fucoidans are of importance for their recently discovered contribution to marine carbon dioxide sequestration and due to their potential applications in biotechnology and biomedicine. However, fucoidans have high intra- and intermolecular diversity that challenges assignment of structure to biological function and the development of applications. Fucoidan-active enzymes may be used to simplify this diversity by producing defined oligosaccharides more applicable for structural refinement, characterization, and structure to function assignment for example via bioassays. In this study, we combined MALDI mass spectrometry with biocatalysis to show that the endo-fucoidanases P5AFcnA and Wv323 can produce defined oligosaccharide structures directly from unrefined macroalgal biomass. P5AFcnA released oligosaccharides from seven commercial fucoidan extracts in addition to unrefined biomass of three macroalgae species indicating a broadly applicable approach reproducible across 10 species. Both MALDI-TOF/TOF and AP-MALDI-Orbitrap systems were used, demonstrating that the approach is not instrument-specific and exploiting their combined high-throughput and high-resolution capabilities. Overall, the combination of MALDI-MS and endo-fucoidanase assays offers high-throughput evaluation of fucoidan samples and also enables extraction of defined oligosaccharides of known structure from unrefined seaweed biomass.


Assuntos
Glicosídeo Hidrolases , Polissacarídeos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Polissacarídeos/química , Glicosídeo Hidrolases/metabolismo , Glicosídeo Hidrolases/química , Hidrólise , Alga Marinha/química , Phaeophyceae/química , Phaeophyceae/enzimologia , Oligossacarídeos/química , Biomassa
7.
Langmuir ; 40(23): 12167-12178, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38808371

RESUMO

Gold nanoparticles (AuNPs) hold promise in biomedicine, but challenges like aggregation, protein corona formation, and insufficient biocompatibility must be thoroughly addressed before advancing their clinical applications. Designing AuNPs with specific protein corona compositions is challenging, and strategies for corona elimination, such as coating with polyethylene glycol (PEG), have limitations. In this study, we introduce a commercially available zwitterionic derivative of glutathione, glutathione monoethyl ester (GSHzwt), for the surface coating of colloidal AuNPs. Particles coated with GSHzwt were investigated alongside four other AuNPs coated with various ligands, including citrate ions, tiopronin, glutathione, cysteine, and PEG. We then undertook a head-to-head comparison of these AuNPs to assess their behavior in biological fluid. GSHzwt-coated AuNPs exhibited exceptional resistance to aggregation and protein adsorption. The particles could also be readily functionalized with biotin and interact with streptavidin receptors in human plasma. Additionally, they exhibited significant blood compatibility and noncytotoxicity. In conclusion, GSHzwt provides a practical and easy method for the surface passivation of AuNPs, creating "stealth" particles for potential clinical applications.


Assuntos
Glutationa , Ouro , Nanopartículas Metálicas , Propriedades de Superfície , Ouro/química , Nanopartículas Metálicas/química , Glutationa/química , Humanos , Tamanho da Partícula , Adsorção , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia
8.
Arch Cardiol Mex ; 2024 May 08.
Artigo em Espanhol | MEDLINE | ID: mdl-38718424

RESUMO

Objective: To describe and evaluate the outcomes of ductal angioplasty with stent placement at a single high-complexity center during the period 2016-2022. Method: A retrospective descriptive cross-sectional study was conducted, including patients under 3 months of age who underwent ductal stent implantation as initial palliative treatment. Demographic, clinical, and anatomical data were collected before the intervention. Mortality, intra- and post-procedural complications, need for re-intervention, intensive care requirements, and hospital stay were recorded. The characteristics at the time of definitive surgery are described. Discrete variables are presented as percentages, and continuous variables are presented with their medians and respective interquartile ranges. Results: Twenty patients who underwent this treatment were reviewed, revealing a success rate of 80%. Complications due to stent dysfunction required surgical resolution. 95% of patients were dischargedfrom the institution after the procedure, and 17 patients reached a second definitive surgical stage. Three patients died afterthe procedure, but with no direct relation to it. Conclusions: Indications for ductal angioplasty with stent as an alternative treatment to systemic-pulmonary anastomosis by surgery are not yet fully defined; the strategy represents a valid alternative in appropriately selected patients. The presented experience shows results similar to international reference centers.


Objetivo: Describir y evaluar los resultados de la angioplastia con stent ductal en un único centro de alta complejidad durante el periodo 2016-2022. Método: Estudio descriptivo retrospectivo de corte transversal en el que se incluyeron pacientes menores de 3 meses a quienes se implantó un stent en el conducto arterioso como tratamiento paliativo inicial. Se recolectaron datos demográficos, clínicos y anatómicos previos a la intervención. Se registraron la mortalidad, las complicaciones intra- y posprocedimiento, la necesidad de reintervención, los requerimientos de cuidados intensivos y la estadía hospitalaria. Se describen las características al momento de la cirugía definitiva. Las variables discretas son presentadas con porcentajes, y las variables continuas con sus medianas y sus respectivos intervalos intercuartílicos. Resultados: Se revisaron 20 pacientes que habían recibido este tratamiento y se evidenció una tasa de éxito del 80%. Las complicaciones por disfunción del stent requirieron resolución quirúrgica. Egresaron de la institución el 95% de los pacientes luego del procedimiento y lograron arribar a un segundo estadio quirúrgico definitivo 17 pacientes. Fallecieron tres pacientes luego del procedimiento, pero sin relación directa con este. Conclusiones: Las indicaciones de angioplastia del conducto con stent como tratamiento alternativo a la realización de una anastomosis sistémico-pulmonar por cirugía todavía no están completamente definidas; la estrategia constituye una alternativa válida en pacientes adecuadamente seleccionados. La experiencia presentada muestra resultados similares a los de otros centros de referencia internacional.

10.
J Appl Biomech ; 40(3): 241-249, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38604601

RESUMO

This study estimated the contribution of the midfoot joint complex (MJC) kinematics to the pelvis anterior-posterior positions during the stance phase of walking and investigated whether the MJC is functionally coordinated with the lower limb joints to maintain similar pelvic positions across steps. Hip, knee, ankle, and MJC sagittal angles were measured in 11 nondisabled participants during walking. The joints' contributions to pelvic positions were computed through equations derived from a link-segment model. Functional coordination across steps was identified when the MJC contribution to pelvic position varied and the summed contributions of other joints varied in the opposite direction (strong negative covariations [r ≤ -.7] in stance phase instants). We observed that the MJC plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. The MJC was the second joint that contributed most to the pelvis positions (around 18% of all joints' contributions), after the ankle joint. The MJC and ankle were the joints that were most frequently coordinated with the other joints (≅70% of the stance phase duration). The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints.


Assuntos
Caminhada , Humanos , Masculino , Caminhada/fisiologia , Fenômenos Biomecânicos , Feminino , Adulto , Extremidade Inferior/fisiologia , Articulação do Tornozelo/fisiologia , Articulações do Pé/fisiologia , Pé/fisiologia , Pelve/fisiologia , Articulação do Quadril/fisiologia
11.
PLoS One ; 19(4): e0292512, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38626030

RESUMO

Research ethics review committees (ERCs) worldwide faced daunting challenges during the COVID-19 pandemic. There was a need to balance rapid turnaround with rigorous evaluation of high-risk research protocols in the context of considerable uncertainty. This study explored the experiences and performance of ERCs during the pandemic. We conducted an anonymous, cross-sectional, global online survey of chairs (or their delegates) of ERCs who were involved in the review of COVID-19-related research protocols after March 2020. The survey ran from October 2022 to February 2023 and consisted of 50 items, with opportunities for descriptive responses to open-ended questions. Two hundred and three participants [130 from high-income countries (HICs) and 73 from low- and middle-income countries (LMICs)] completed our survey. Respondents came from diverse entities and organizations from 48 countries (19 HICs and 29 LMICs) in all World Health Organization regions. Responses show little of the increased global funding for COVID-19 research was allotted to the operation of ERCs. Few ERCs had pre-existing internal policies to address operation during public health emergencies, but almost half used existing guidelines. Most ERCs modified existing procedures or designed and implemented new ones but had not evaluated the success of these changes. Participants overwhelmingly endorsed permanently implementing several of them. Few ERCs added new members but non-member experts were consulted; quorum was generally achieved. Collaboration among ERCs was infrequent, but reviews conducted by external ERCs were recognized and validated. Review volume increased during the pandemic, with COVID-19-related studies being prioritized. Most protocol reviews were reported as taking less than three weeks. One-third of respondents reported external pressure on their ERCs from different stakeholders to approve or reject specific COVID-19-related protocols. ERC members faced significant challenges to keep their committees functioning during the pandemic. Our findings can inform ERC approaches towards future public health emergencies. To our knowledge, this is the first international, COVID-19-related study of its kind.


Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , Pandemias , Estudos Transversais , Emergências , Ética em Pesquisa
12.
Artigo em Inglês | MEDLINE | ID: mdl-38452754

RESUMO

In this work, the prepared cobalt oxide decorated boron-doped g-C3N4 (CoOx/g-C3N4) heterojunction exhibits remarkable activity in CO2 reduction (CO2RR), resulting in high yields of CH3COOH (∼383 µmol·gcatalyst-1) and CH3OH (∼371 µmol·gcatalyst-1) with 58% selectivity to C2+ under visible light. However, the same system leads to high H2 evolution (HER) by increasing the cobalt oxide content, suggesting that the selectivity and preference for the CO2RR or HER depend on oxide decoration. By comparing HER and CO2RR evolution in the same system, this work provides critical insights into the catalytic mechanism, indicating that the CoOx/g-C3N4 heterojunction formation is necessary to foster high visible light photoactivity.

13.
Public Health Genomics ; 27(1): 68-73, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38508152

RESUMO

One of the primary public health functions of a tuberculosis (TB) program is to arrest the spread of infection. Traditionally, TB programs have relied on epidemiological information, gathered through contact tracing, to infer that transmission has occurred between people. The ability of drawing such inferences is extensively context dependent. Where epidemiological information has been strong, such as 2 cases of TB occurring sequentially within a single household, confidence in such inferences is high; conversely, public health authorities have been less certain about the significance of TB cases merely occurring in the same wider social group or geographic area. Many current laboratory tests for TB used globally may be sufficient to confirm a diagnosis and guide appropriate therapy but still be insufficiently precise for distinguishing two strains reliably. In short, drawing inferences regarding a chain of transmissions has always been as much art as science.


Assuntos
Tuberculose , Sequenciamento Completo do Genoma , Humanos , Tuberculose/epidemiologia , Tuberculose/diagnóstico , Tuberculose/transmissão , Tuberculose/genética , Sequenciamento Completo do Genoma/métodos , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/isolamento & purificação , Busca de Comunicante/métodos , Saúde Pública/métodos , Narração
14.
Clin Rheumatol ; 43(5): 1615-1622, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38436770

RESUMO

OBJECTIVES: (I) To identify and measure the clinical consequences of a delayed diagnosis in patients with primary obstetric antiphospholipid syndrome (POAPS), in terms of time and events associated to antiphospholipid syndrome (APS), and (II) to evaluate the impact of their treatment status on perinatal outcomes, before and after diagnosis. METHODS: This retrospective multicentre study included 99 POAPS women who were separated in two groups of timelines based on their diagnostic status: group 1: women who met the clinical criteria for POAPS; group 2: included the same patients from group 1 since they meet the laboratory criteria for APS. In group 1, we assessed the following variables: obstetric events, thrombotic events and time (years) to diagnosis of APS. We also compared perinatal outcomes between patients in group 1 vs. group 2. Women in group 2 were treated with standard of care for POAPS. Simple and multivariable logistic regression analyses were performed. RESULTS: Regarding the impact of the delay on diagnosis, a total of 87 APS-related events were recorded: 46 miscarriages, 32 foetal losses and 9 premature deliveries before the 34th week due to preeclampsia, and one thrombosis. The estimated rate of preventable events was 20.58 per year/100 patients. The mean diagnostic delay time was 4.27 years. When we compared both groups during pregnancy, we found that patients in group 1 (no treatment) had a higher association with pregnancy losses [OR = 6.71 (95% CI: 3.59-12.55), p < 0.0001]. CONCLUSION: Our findings emphasize the negative impact of POAPS underdiagnosis on patient health and the critical importance of a timely intervention to improve pregnancy outcomes. Key Points •Our study shows the relevance of underdiagnosis on primary obstetric antiphospholipid syndrome (POAPS). •These patients presented a high risk of APS-related events with each passing year. •Shorter diagnostic delay time was observed in the reference centres.


Assuntos
Aborto Espontâneo , Síndrome Antifosfolipídica , Trombose , Gravidez , Humanos , Feminino , Síndrome Antifosfolipídica/diagnóstico , Síndrome Antifosfolipídica/terapia , Síndrome Antifosfolipídica/complicações , Anticorpos Antifosfolipídeos , Diagnóstico Tardio , Resultado da Gravidez , Trombose/complicações
15.
Land Econ ; 100(1): 89-108, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38515763

RESUMO

This study uses Zillow's ZTRAX property transaction database to investigate variation in hedonic price effects of water clarity on single-family houses throughout the United States. We consider five spatial scales and estimate models using different sample selection criteria and model specifications. Our results indicate considerable spatial heterogeneity both within and across the four U.S. Census regions. However, we also find heterogeneity resulting from different types of investigator decisions, including sample selection and modelling choices. Thus, it is necessary to use practical knowledge to consider the limits of market areas and to investigate the robustness of estimation results to investigator choices. (JEL Q51).

17.
Brain Commun ; 6(1): fcad273, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38173802

RESUMO

Mutations in CLCN2 are a rare cause of autosomal recessive leucoencephalopathy with ataxia and specific imaging abnormalities. Very few cases have been reported to date. Here, we describe the clinical and imaging phenotype of 12 additional CLCN2 patients and expand the known phenotypic spectrum of this disorder. Informed consent was obtained for all patients. Patients underwent either whole-exome sequencing or focused/panel-based sequencing to identify variants. Twelve patients with biallelic CLCN2 variants are described. This includes three novel likely pathogenic missense variants. All patients demonstrated typical MRI changes, including hyperintensity on T2-weighted images in the posterior limbs of the internal capsules, midbrain cerebral peduncles, middle cerebellar peduncles and cerebral white matter. Clinical features included a variable combination of ataxia, headache, spasticity, seizures and other symptoms with a broad range of age of onset. This report is now the largest case series of patients with CLCN2-related leucoencephalopathy and reinforces the finding that, although the imaging appearance is uniform, the phenotypic expression of this disorder is highly heterogeneous. Our findings expand the phenotypic spectrum of CLCN2-related leucoencephalopathy by adding prominent seizures, severe spastic paraplegia and developmental delay.

18.
J Plant Physiol ; 294: 154183, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38295651

RESUMO

Because its impact in plant development and growth and its interaction with Na+ and Cl-, the supply of different N-forms to crops can be an easy-to-use tool with effective results on salinity tolerance. Here the effect of four N-NO3-/N-NH4+ ratios (mM; 2/0, 1.6/0.4, 0.4/1.6, 0/2) on adaptation to salt conditions (15 mM NaCl in a first experiment and 40 mM NaCl in a second experiment) was studied in young lettuce (cv "Summer wonder") plants. The experiments were carried out in greenhouse and under hydroponics conditions. The results show that this cultivar tolerates and adapts to moderate salinity by deploying several structural and physiological mechanisms; (i) increasing allocation of biomass to the root, (ii) increasing root Na+ uptake and storing it in the shoot and root tissues, (iii) increasing intrinsic water use efficiency and (iv) increasing root N and P uptake. The beneficial effect of salt exposure on growth was greater when the predominant N-form was N-NO3-. These plants with higher tissue N-NO3- concentration, decreased Cl- uptake and shoot and root Cl- concentration. Regardless of salt conditions, plants with a high proportion of N-NH4+ (1.6 mM) and a low proportion of N-NO3- (0.4 mM) had a greater growth and nitrogen use efficiency, that was associated with the improved uptake of nutrients, and the maintenance of water status.


Assuntos
Compostos de Amônio , Nitratos , Nitratos/farmacologia , Lactuca , Cloreto de Sódio/farmacologia , Salinidade , Água , Raízes de Plantas , Nitrogênio/farmacologia
19.
Plant Physiol Biochem ; 207: 108372, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38228015

RESUMO

Castor (Ricinus communis) is a relevant industrial oilseed feedstock for many industrial applications, being globally mainly cultivated by smallholder farmers in semiarid areas, where abiotic stresses predominate. Therefore, susceptible to generating reactive oxygen species (ROS) and subsequent oxidative stress, compromising cell metabolism upon seed imbibition and germination, seedling and crop establishment, and yield. The present study evaluated the consequences of water restriction by Polyethylene glycol (PEG) and Sodium chloride (NaCl) on cell cycle and metabolism reactivation on germinability, seedling growth, and vigor parameters in 2 commercial castor genotypes (Nordestina and Paraguaçu). PEG water restriction inhibited germination completely at -0.23 MPa or higher, presumably due to reduced oxygen availability. The restrictive effects of NaCl saline stress on germination were observed only from -0.46 MPa onwards, affecting dry mass accumulation and the production of normal seedlings. In general, superoxide dismutase (SOD) activity increased in NaCl -0.23 MPa, whereas its modulation during the onset of imbibition (24h) seemed to depend on its initial levels in dry seeds in a genotype-specific manner, therefore, resulting in the higher stress tolerance of Nordestina compared to Paraguaçu. Overall, results show that Castor germination and seedling development are more sensitive to the restrictive effects of PEG than NaCl at similar osmotic potentials, contributing to a better understanding of the responses to water restriction stresses by different Castor genotypes. Ultimately, SOD may constitute a potential marker for characterizing castor genotypes in stressful situations during germination, early seedling, and crop establishment, and a target for breeding for Castor-improved stress tolerance.


Assuntos
Ricinus communis , Plântula , Plântula/metabolismo , Cloreto de Sódio/farmacologia , Cloreto de Sódio/metabolismo , Ricinus communis/genética , Polietilenoglicóis/farmacologia , Polietilenoglicóis/metabolismo , Germinação , Ciclo Celular , Sementes/metabolismo , Água/metabolismo , Superóxido Dismutase/metabolismo
20.
ACS Nano ; 18(4): 3575-3582, 2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38235729

RESUMO

The applications of ultrasound imaging are often limited due to low contrast, which arises from the comparable acoustic impedance of normal tissues and disease sites. To improve the low contrast, we propose a contrast agent called gas-generating laser-activatable nanorods for contrast enhancement (GLANCE), which enhances ultrasound imaging contrast in two ways. First, GLANCE absorbs near-infrared lasers and generates nitrogen gas bubbles through the photocatalytic function of gold nanorods and photolysis of azide compounds. These gas bubbles decrease the acoustic impedance and highlight the injection site from the surrounding tissues. Second, GLANCE exhibits photoacoustic properties owing to the gold nanorods that emit photoacoustic signals upon laser irradiation. Additionally, GLANCE offers several benefits for biomedical applications such as nanometer-scale size, adjustable optical absorption, and biocompatibility. These distinctive features of GLANCE would overcome the limitations of conventional ultrasound imaging and facilitate the accurate diagnosis of various diseases.


Assuntos
Nanotubos , Técnicas Fotoacústicas , Ouro , Técnicas Fotoacústicas/métodos , Diagnóstico por Imagem , Ultrassonografia/métodos , Meios de Contraste
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...