RESUMO
A growing wealth of data suggest that reactive oxygen species (ROS) signalling might be crucial in conferring embryonic or adult stem cells their specific properties. However, how stem cells control ROS production and scavenging, and how ROS in turn contribute to stemness, remain poorly understood. Using the Xenopus retina as a model system, we first investigated the redox status of retinal stem cells (RSCs). We discovered that they exhibit higher ROS levels compared with progenitors and retinal neurons, and express a set of specific redox genes. We next addressed the question of ROS functional involvement in these cells. Using pharmacological or genetic tools, we demonstrate that inhibition of NADPH oxidase-dependent ROS production increases the proportion of quiescent RSCs. Surprisingly, this is accompanied by an apparent acceleration of the mean division speed within the remaining proliferating pool. Our data further unveil that such impact on RSC cell cycling is achieved by modulation of the Wnt/Hedgehog signalling balance. Altogether, we highlight that RSCs exhibit distinctive redox characteristics and exploit NADPH oxidase signalling to limit quiescence and fine-tune their proliferation rate.
Assuntos
Células-Tronco Adultas , Células-Tronco Neurais , Animais , Xenopus laevis/metabolismo , Espécies Reativas de Oxigênio , Proliferação de Células , Proteínas Hedgehog , Retina/metabolismo , Células-Tronco Adultas/metabolismo , NADPH Oxidases/genética , Via de Sinalização WntRESUMO
Difenoconazole is a chemical entity containing two chiral centers and having four stereoisomers: (2R,4R)-, (2R,4S)-, (2S,4R)- and (2S,4S)-difenoconazole, the marketed product containing a mixture of these isomers. Residues of difenoconazole have been identified in many agricultural products and drinking water. A computational approach has been used to evaluate the toxicological effects of the difenoconazole stereoisomers on humans. It integrates predictions of absorption, distribution, metabolism, excretion and toxicity (ADMET) profiles, prediction of metabolism sites, and assessment of the interactions of the difenoconazole stereoisomers with human cytochromes, nuclear receptors and plasma proteins by molecular docking. Several toxicological effects have been identified for all the difenoconazole stereoisomers: high plasma protein binding, inhibition of cytochromes, possible hepatotoxicity, neurotoxicity, mutagenicity, skin sensitization potential, moderate potential to produce endocrine disrupting effects. There were small differences in the predicted probabilities of producing various biological effects between the distinct stereoisomers of difenoconazole. Furthermore, there were significant differences between the interacting energies of the difenoconazole stereoisomers with plasma proteins and human cytochromes, the spectra of the hydrogen bonds and aromatic donor-acceptor interactions being quite distinct. Some distinguishing results have been obtained for the (2S,4S)-difenoconazole: it registered the highest value for clearance, exposed reasonable probabilities to produce cardiotoxicity and carcinogenicity and negatively affected numerous nuclear receptors.
Assuntos
Quimioinformática , Citocromos , Dioxolanos , Humanos , Simulação de Acoplamento Molecular , Estereoisomerismo , TriazóisRESUMO
Triticonazole is a fungicide used to control diseases in numerous plants. The commercial product is a racemate containing (R)- and (S)-triticonazole and its residues have been found in vegetables, fruits, and drinking water. This study considered the effects of triticonazole on soil microorganisms and enzymes and human health by taking into account the enantiomeric structure when applicable. An experimental method was applied for assessing the effects of triticonazole on soil microorganisms and enzymes, and the effects of the stereoisomers on soil enzymes and human health were assessed using a computational approach. There were decreases in dehydrogenase and phosphatase activities and an increase in urease activity when barley and wheat seeds treated with various doses of triticonazole were sown in chernozem soil. At least 21 days were necessary for the enzymes to recover the activities. This was consistent with the diminution of the total number of soil microorganisms in the 14 days after sowing. Both stereoisomers were able to bind to human plasma proteins and were potentially inhibitors of human cytochromes, revealing cardiotoxicity and low endocrine disruption potential. As distinct effects, (R)-TTZ caused skin sensitization, carcinogenicity, and respiratory toxicity. There were no significant differences in the interaction energies of the stereoisomers and soil enzymes, but (S)-TTZ exposed higher interaction energies with plasma proteins and human cytochromes.
Assuntos
Água Potável , Fungicidas Industriais , Poluentes do Solo , Ciclopentanos , Citocromos , Fungicidas Industriais/química , Humanos , Oxirredutases , Monoéster Fosfórico Hidrolases , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise , Triazóis , UreaseRESUMO
It is widely recognized that chitin and chitosan are potential sources of bioactive materials and that their oligosaccharides reveal various biological activities (including antimicrobial) that are correlated with their structures and physicochemical properties. This study uses the molecular docking approach to assess the interactions of small chito-oligosaccharides (MW< 1500 Da) with plasma proteins in order to obtain information regarding their fate of distribution in the human organism. There are favorable interactions of small chito-oligomers with plasma proteins, the interactions with human serum albumin being stronger than those with α-1-acid glycoprotein. The interaction energies increase with increasing the molecular weight, decrease with increasing deacetylation degrees and are reliant on the deacetylation pattern. This study could inform the application of chito-oligosaccharides with varying molecular weights, degrees, and patterns of deacetylation in human health.
Assuntos
Proteínas Sanguíneas/metabolismo , Quitina/análogos & derivados , Simulação de Acoplamento Molecular , Acetilação , Quitina/química , Quitina/metabolismo , Quitosana , Humanos , Peso Molecular , Oligossacarídeos , Albumina Sérica Humana/metabolismoRESUMO
PURPOSE: The aim of this study is to use computational approaches to predict the ADME-Tox profiles, pharmacokinetics, molecular targets, biological activity spectra and side/toxic effects of 31 anabolic and androgen steroids in humans. METHODS: The following computational tools are used: (i) FAFDrugs4, SwissADME and admetSARfor obtaining the ADME-Tox profiles and for predicting pharmacokinetics;(ii) SwissTargetPrediction and PASS online for predicting the molecular targets and biological activities; (iii) PASS online, Toxtree, admetSAR and Endocrine Disruptomefor envisaging the specific toxicities; (iv) SwissDock to assess the interactions of investigated steroids with cytochromes involved in drugs metabolism. RESULTS: Investigated steroids usually reveal a high gastrointestinal absorption and a good oral bioavailability, may inhibit someof the human cytochromes involved in the metabolism of xenobiotics (CYP2C9 being the most affected) and reflect a good capacity for skin penetration. There are predicted numerous side effects of investigated steroids in humans: genotoxic carcinogenicity, hepatotoxicity, cardiovascular, hematotoxic and genitourinary effects, dermal irritations, endocrine disruption and reproductive dysfunction. CONCLUSIONS: These results are important to be known as an occupational exposure to anabolic and androgenic steroids at workplaces may occur and because there also is a deliberate human exposure to steroids for their performance enhancement and anti-aging properties.
Assuntos
Anabolizantes/farmacologia , Androgênios/farmacologia , Modelos Biológicos , Substâncias para Melhoria do Desempenho/farmacologia , Anabolizantes/química , Androgênios/química , Atletas , Simulação por Computador , Drogas Desenhadas/química , Drogas Desenhadas/farmacologia , Interações Medicamentosas , Uso Indevido de Medicamentos/efeitos adversos , Humanos , Simulação de Acoplamento Molecular , Exposição Ocupacional/efeitos adversos , Substâncias para Melhoria do Desempenho/química , Absorção Cutânea , Drogas Veterinárias/química , Drogas Veterinárias/farmacologia , Local de TrabalhoRESUMO
OBJECTIVES: To evaluate if the timing of appearance with respect to disease onset may influence the arthritis presentation pattern in antisynthetase syndrome (ASSD). METHODS: The patients were selected from a retrospective large international cohort of ASSD patients regularly followed-up in centres referring to AENEAS collaborative group. Patients were eligible if they had an antisynthetase antibody testing positive in at least two determinations along with arthritis occurring either at ASSD onset (Group 1) or during the course of the disease (Group 2). RESULTS: 445 (70%; 334 females, 110 males, 1 transsexual) out of the 636 ASSD we collected had arthritis, in the majority of cases (367, 83%) from disease onset (Group 1). Patients belonging to Group 1 with respect to Group 2 had an arthritis more commonly polyarticular and symmetrical (p=0.015), IgM-Rheumatoid factor positive (p=0.035), erosions at hands and feet plain x-rays (p=0.036) and more commonly satisfying the 1987 revised classification criteria for rheumatoid arthritis (RA) (p=0.004). Features such as Raynaud's phenomenon, mechanic's hands and fever (e.g. accompanying findings) were more frequently reported in Group 2 (p=0.005). CONCLUSIONS: In ASSD, the timing of appearance with respect to disease onset influences arthritis characteristics. In particular, RA features are more common when arthritis occurs from ASSD onset, suggesting an overlap between RA and ASSD in these patients. When arthritis appears during the follow-up, it is very close to a connective tissue disease-related arthritis. Also, the different prevalence of accompanying features between these two groups is in line with this possibility.
Assuntos
Artrite/epidemiologia , Miosite/epidemiologia , Adulto , Artrite/diagnóstico , Artrite/imunologia , Autoanticorpos/sangue , Biomarcadores/sangue , Europa (Continente)/epidemiologia , Feminino , Humanos , Masculino , México/epidemiologia , Pessoa de Meia-Idade , Miosite/diagnóstico , Miosite/imunologia , Fenótipo , Prevalência , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Fatores de TempoRESUMO
BACKGROUND: In order to understand why rates of overweight and obesity are so high in the Ecuadorian province of Galapagos, this study analyzes changes in household food expenditures and perceptions and practices related to food consumption patterns. Galapagos is understood as an unusual but not unique case because conditions there graphically illustrate trends observed in communities and countries worldwide. A mixed methods approach was employed: a quantitative component was based on expenditures for foods classified according to the NOVA system, and a qualitative component utilized focus group discussions, key informant interviews, and structured observations. RESULTS: Galapagos residents increased consumption of processed and ultra-processed foods and decreased consumption of unprocessed and minimally processed foods. Perceived barriers to healthy diets include price, availability, and quality of fresh produce, as well as easy access to industrialized processed and ultra-processed foods. CONCLUSIONS: Changes in consumption patterns represent both local conditions and global trends; in that sense, the factors that affect Galapagos residents are not unique. Hence, these findings help elucidate processes observed in communities around the world.
Assuntos
Dieta/estatística & dados numéricos , Fast Foods/efeitos adversos , Obesidade/epidemiologia , Sobrepeso/epidemiologia , Adulto , Inquéritos sobre Dietas , Equador/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pesquisa Qualitativa , Adulto JovemRESUMO
To describe disease activity and disability during the first year of follow-up, from rheumatoid arthritis (RA) patients who discontinue tofacitinib after they end participation in a clinical trial. From 2008 to 2016, 36 patients were enrolled in the "Long term follow-up study with tofacitinib (and methotrexate) for RA treatment". At the end of the study, tofacitinib was discontinued and patients were proposed to enter an observational study; 35 agree and had scheduled evaluations at baseline, at 15 and 30 days of follow-up, at month 2 and 3, and thereafter every 3 months. Disease activity was evaluated as per DAS28-ESR and disability as per HAQ. During follow-up, treatment was treat-to-target oriented, only conventional DMARDs were indicated. Descriptive statistics and nonparametric test were used. The study was approved by IRB. Patients were primarily females (N = 34), had median (Q25-75) age of 52 years (45-58), and had received tofacitinib for a median of 7.9 years (6.3-8.3). The proportion of patients with remission and low disease activity decreased from day 30 of follow-up and recovered after 270 days, meanwhile patients with high disease activity increased from 0% at baseline to 6.3% at 1 year. At study entry, 20 patients had remission/low disease activity; during follow-up, 85% deteriorated after (median) 30 days; among them, 23.5% recovered their baseline status after a median of 172.5 days. The HAQ showed a similar behavior, but 66.7% recovered. A substantial proportion of RA patients deteriorated outcomes early after tofacitinib cessation; some patients recovered baseline status with traditional DMARDS.
Assuntos
Antirreumáticos/uso terapêutico , Artrite Reumatoide/tratamento farmacológico , Ética em Pesquisa , Metotrexato/uso terapêutico , Piperidinas/uso terapêutico , Inibidores de Proteínas Quinases/uso terapêutico , Pirimidinas/uso terapêutico , Pirróis/uso terapêutico , Projetos de Pesquisa , Sujeitos da Pesquisa , Populações Vulneráveis , Adulto , Idoso , Antirreumáticos/efeitos adversos , Artrite Reumatoide/diagnóstico , Avaliação da Deficiência , Progressão da Doença , Quimioterapia Combinada , Feminino , Humanos , Masculino , Metotrexato/efeitos adversos , Pessoa de Meia-Idade , Piperidinas/efeitos adversos , Inibidores de Proteínas Quinases/efeitos adversos , Pirimidinas/efeitos adversos , Pirróis/efeitos adversos , Recidiva , Indução de Remissão , Fatores de Tempo , Resultado do TratamentoRESUMO
Fungicides play an important role in crop protection, but they have also been shown to adversely affect non-target organisms, including those living in the aquatic environment. The aim of the present study is to combine experimental and computational approaches to evaluate the effects of flutriafol, metconazole, myclobutanil, tebuconazole, tetraconazole and triticonazole on aquatic model organisms and to obtain information on the effects of these fungicides on Lemna minor, a freshwater plant, at the molecular level. The EC50 (the half-maximum effective concentration) values for the growth inhibition of Lemna minor in the presence of the investigated fungicides show that metconazole (EC50 = 0.132 mg/L) and tetraconazole (EC50 = 0.539 mg/L) are highly toxic, tebuconazole (EC50 = 1.552 mg/L), flutriafol (EC50 = 3.428 mg/L) and myclobutanil (EC50 = 9.134 mg/L) are moderately toxic, and triticonazole (EC50 = 11.631 mg/L) is slightly toxic to this plant. The results obtained with the computational tools TEST, ADMETLab2.0 and admetSAR2.0 also show that metconazole and tetraconazole are toxic to other aquatic organisms: Pimephales promelas, Daphnia magna and Tetrahymena pyriformis. A molecular docking study shows that triazole fungicides can affect photosynthesis in Lemna minor because they strongly bind to C43 (binding energies between -7.44 kcal/mol and -7.99 kcal/mol) and C47 proteins (binding energies between -7.44 kcal/mol and -8.28 kcal/mol) in the reaction center of photosystem II, inhibiting the binding of chlorophyll a to these enzymes. In addition, they can also inhibit glutathione S-transferase, an enzyme involved in the cellular detoxification of Lemna minor.
RESUMO
The 2021 La Palma eruption provided an unpreceded opportunity to test the relationship between earthquake hypocenters and the location of magma reservoirs. We performed density measurements on CO2-rich fluid inclusions (FIs) hosted in olivine crystals that are highly sensitive to pressure via calibrated Raman spectroscopy. This technique can revolutionize our knowledge of magma storage and transport during an ongoing eruption, given that it can produce precise magma storage depth constraints in near real time with minimal sample preparation. Our FIs have CO2 recorded densities from 0.73 to 0.98 g/cm3, translating into depths of 15 to 27 km, which falls within the reported deep seismic zone recording the main melt storage reservoir.
RESUMO
Many previous studies presented the effectiveness of ketoconazole (KTZ) against leishmaniasis. However, the bioavailability and therapeutic efficacy of free KTZ are limited due to its low aqueous solubility. In this study, an inclusion complex (IC6HKTZ) was prepared with p-sulfonic acid calix[6]arene (CX6SO3H) to improve the solubility and efficacy of KTZ against Leishmania amazonensis and Leishmania infantum promastigotes. A linear increase in KTZ solubility as a function of CX6SO3H concentration was verified using the phase-solubility diagram. The resulting diagram was classified as AL-type and a 1:1 host-guest stoichiometry was assumed to prepare IC6HKTZ by freeze-drying. FTIR, TG/DSC, XRD, and solid-state 13C NMR spectroscopy analyses were performed to confirm the formation of IC6HKTZ. The solubility enhancement of KTZ by 120.00 µM CX6SO3H was about 95 times. The IC50 values of IC6HKTZ and free KTZ were 3.95 and 14.35 µM for Leishmania amazonensis and 6.74 and 17.47 µM for Leishmania infantum, respectively. The viability of DH82 macrophages was not affected by CX6SO3H. These results show that CX6SO3H is a new supramolecular carrier system that improves antileishmanial activities to KTZ for the treatment of cutaneous and visceral leishmaniasis.
Assuntos
Antiprotozoários , Leishmania infantum , Leishmania mexicana , Animais , Camundongos , Cetoconazol , Antiprotozoários/uso terapêutico , Macrófagos , Camundongos Endogâmicos BALB CRESUMO
Since 1999, the Dikika Research Project (DRP; initiated by Z.A.) has conducted surveys and excavations in badlands that expose Pliocene and Pleistocene sediments south of the Awash River in Ethiopia, between surrounding hominin localities at Hadar, Gona and the Middle Awash region. Here we report our geological mapping and stratigraphic measurement of the DRP area, and the context of a remarkably well-preserved skeleton of the earliest known juvenile hominin at the Dikika DIK-1 locality. Our mapping of the DRP area permits a complete definition of the hominin-bearing Hadar Formation and provides a cohesive structural and tectonic framework defining its relationships to adjacent strata. Our findings reveal the basin-scale tectonic, depositional and palaeoenvironmental history of the area, as well as a clear taphonomic and palaeontological context for the juvenile hominin. Such data are crucial for understanding the environmental context of human evolution, and can be integrated into larger-scale tectonic and palaeoenvironmental studies. Our basin-scale approach to palaeoenvironments provides a means to elucidate the complex geological history occurring at the scale of temporally and geographically controlled fossil point localities, which occur within the rich tectonic and depositional history of the Awash Valley.
Assuntos
Fósseis , Hominidae , Paleontologia , Esqueleto , Animais , Evolução Biológica , Ecossistema , Etiópia , Sedimentos Geológicos , História Antiga , Hominidae/fisiologia , Humanos , Fatores de TempoRESUMO
Vanguard efforts in forecasting volcanic eruptions are turning to physics-based models, which require quantitative estimates of magma conditions during pre-eruptive storage. Below active arc volcanoes, observed magma storage depths vary widely (~0 to 20 kilometers) and are commonly assumed to represent levels of neutral buoyancy. Here we show that geophysically observed magma depths (6 ± 3 kilometers) are greater than depths of neutral buoyancy, ruling out this commonly assumed control. Observed depths are instead consistent with predicted depths of water degassing. Intrinsically wetter magmas degas water and crystallize deeper than dry magmas, resulting in viscosity increases that lead to deeper stalling of ascending magma. The water-depth relationship provides a critical constraint for forecasting models by connecting depth of eruption initiation to its volatile fuel.
RESUMO
This study aimed at the extraction and encapsulation of the carotenoids from sea buckthorn fruits and obtaining value-added mayonnaise. First, the carotenoids from sea buckthorn fruits were extracted using ultrasound-assisted extraction. Then, they were microencapsulated through complex coacervation and freeze-drying techniques using different wall material combinations. Two powders were obtained and analyzed in terms of encapsulation efficiency, total carotenoid content, antioxidant activity, stability of phytochemicals and color, morphological structure, and in vitro digestibility. All results pointed out that the carotenoid molecules were successfully encapsulated within the mixture of alginate, agar, and chitosan, with a 61.17 ± 0.89% encapsulation efficiency. To probe the functionality, the powder was added into mayonnaise in 2.5% and 5% amounts. The obtained mayonnaise samples were characterized in terms of phytochemical and antioxidant activity properties with their storage stability and texture, color, and sensory characteristics. A significant increase of total carotenoid content and antioxidant activity compared to the control sample was observed. The addition of powder also led to improved texture by increasing the firmness and adhesion. In addition, the sensory evaluation indicated an improved color and overall acceptability of the value-added mayonnaise. Thus, sea buckthorn extracts may be considered as valuable ingredients for the development of added-value food products.
RESUMO
OBJECTIVES: We hypothesized that RA disease activity might be associated with the survival of RA-ILD patients. To evaluate this possibility, we analyzed data on disease activity during follow-up in an RA-ILD cohort and compared disease activity between surviving patients and those who died during follow-up. METHODS: RA-ILD patients referred for medical evaluation and treatment at a single center, with CDAI scores during all follow up were included. We estimated the HR of the mean of the CDAI score during follow-up with survival. Also, we compared the survival function of patients with high disease activity (CDAI scores ≥ 22) during all follow-up with those with moderate and low disease activity. RESULTS: Thirty-seven patients were included. The mean of the CDAI score during follow-up was higher in death patients (median 30.8 ± 18.5 Vs. 16.8 ± 11.3), and a single unit increase in the mean of the CDAI score was associated with non-survival, HR:1.07 (95% CI: 1.02 -1.12). Patients with high disease activity during all follow-up (CDAI scores > 22) had lower survival function in comparison with moderate and low disease activity (P = 0.042). CONCLUSION: The results of the study suggest that higher RA disease activity is associated with a worse prognosis of RA-ILD patients. The hypothesis that high disease activity is associated with worse survival in RA-ILD patients must be evaluated in more extensive cohort studies and clinical trials. KEY POINTS: ⢠RA-ILD patients with high disease activity during follow-up had a worse prognosis than those with moderate or low disease activity. ⢠The study results suggest the hypothesis that patients with RA-ILD must be treated with a treat to target strategy, with the aim of remission or low RA disease activity.
Assuntos
Artrite Reumatoide , Doenças Pulmonares Intersticiais , Artrite Reumatoide/tratamento farmacológico , Estudos de Coortes , Humanos , Prognóstico , Estudos RetrospectivosRESUMO
Levoglucosan (LGA) is a promising chemical platform derived from the pyrolysis of biomass that offers access to a variety of value-added products. We report an efficient route to produce LGA via the pretreatment of biomass with niobium compounds (oxalate, chloride and oxide) followed by fast pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC-MS) at temperatures of 350-600 °C. Catalytic pretreatment reduces the quantity of lignin in the biomass, concentrates the cellulose and enhance LGA formation during fast pyrolysis. The pretreatment also removes alkaline metals, preventing competitive side reactions. The effect of several parameters such as catalyst weight, time, temperature, and solvent, with the optimal pretreatment conditions determined to be 3 (wt.%) niobium oxalate for 1 h at 23 °C in water. Pretreatment increased the LGA yields by 6.40-fold for sugarcane bagasse, 4.15-fold for elephant grass, 4.13-fold for rice husk, 2.86-fold for coffee husk, and 1.86-fold for coconut husk as compared to the raw biomasses. These results indicate that biomass pretreatment using niobium derivates prior fast pyrolysis can be a promising technique for biomass thermochemical conversion in LGA and others important pyrolytic products.
Assuntos
Nióbio , Pirólise , Biomassa , Glucose/análogos & derivados , Temperatura Alta , LigninaRESUMO
Lysozymes that were used in numerous in vitro experiments of chitosan degradation were regularly from hen egg-white. Human lysozyme has been proved to be more active than hen egg-white lysozyme when exerting its bacteriostatic effect and there is possible that the two enzymes have some different structural properties. Consequently, within this study, we compared the structural and physicochemical properties of the human and egg-white lysozymes and used the molecular docking approach to obtain information concerning the specificity of the interactions between chitooligosaccharides with these enzymes. There is 60.47% of identity between the sequences of the human and the hen egg-white lysozymes, but the amino acids that are involved in the interactions of considered lysozymes with N-acetylchitohexaose are well conserved. Superimposition of the structures of investigated lysozymes reveals their structural similarity, the RMSD value being 1.198 Å for 118 equivalent carbon alpha atom pairs from a total of 129. There are some local physicochemical properties like the distribution of the electrostatic potential and the hydrophobicity of the catalytic cavities of the enzyme that are quite different. Substrate specificities of human and hen egg-white lysozyme with respect to chito-oligosaccharides are not clearly distinguishable but they are dependent on the molecular weight, deacetylation degree and pattern of deacetylation.
Assuntos
Quitosana , Muramidase , Animais , Galinhas/metabolismo , Biologia Computacional , Humanos , Simulação de Acoplamento Molecular , Especificidade por SubstratoRESUMO
Processes related to eruptions at arc volcanoes are linked by structures that transect the entire crust. Imaging the mid- to lower-crustal portions (here, ~5-15 km and >15 km respectively) of these magmatic systems where intermediate storage may occur has been a longstanding challenge. Tomography, local seismic source studies, geodetic, and geochemical constraints, are typically most sensitive to shallow (<5 km) storage and/or have insufficient resolution at these depths. Geophysical methods are even further limited at frequently-erupting volcanoes where well-developed trans-crustal magmatic systems are likely to exist, due to a lack of deep seismicity. Here we show direct evidence for mid-crustal magma storage beneath the frequently erupting Cleveland volcano, Alaska, using a novel application of seismic receiver functions. We use P-s scattered waves from the Moho as virtual sources to investigate S-wave velocities between the Moho and the surface. Our forward modeling approach allows us to provide direct constraints on the geometry of low velocity regions beneath volcanoes despite having a comparatively sparse seismic network. Our results show clear evidence of mid-crustal magma storage beneath the depths of located volcanic seismicity. Future work using similar approaches will enable an unprecedented comparative examination of magmatic systems beneath sparsely instrumented volcanoes globally.
RESUMO
Polyhydroxyalkanoates (PHAs) are a large class of polyesters that are biosynthesized by microorganisms at large molecular weights (Mw > 80 kDa) and have a great potential for medical applications because of their recognized biocompatibility. Among PHAs, poly(3-hydroxybutyrate), poly(4-hydroxybutyrate), poly(3-hydroxyvalerate), poly(4-hydroxyvalerate), and their copolymers are proposed to be used in biomedicine, but only poly(4-hydroxybutyrate) has been certified for medical application. Along with the hydrolysis of these polymers, low molecular weight oligomers are released typically. In this study, we have used a computational approach to assess the absorption, distribution, metabolism, and excretion (ADME)-Tox profiles of low molecular weight oligomers (≤32 units) consisting of 3-hydroxybutyrate, 4-hydroxybutyrate, 3-hydroxyvalerate, 4-hydroxyvalerate, 3-hydroxybutyrate-co-3-hydroxyvalerate, and the hypothetical PHA consisting of 4-hydroxybutyrate-co-4-hydroxyvalerate. According to our simulations, these oligomers do not show cardiotoxicity, hepatotoxicity, carcinogenicity or mutagenicity, and are neither substrates nor inhibitors of the cytochromes involved in the xenobiotic's metabolism. They also do not affect the human organic cation transporter 2 (OCT2). However, they are considered to be inhibitors of the organic anion transporters OATP1B1, and OATP1B3. In addition, they may produce eye irritation, and corrosion, skin irritation and have a low antagonistic effect on the androgen receptor.
RESUMO
Polylactic acid (PLA) is a polymer with an increased potential to be used in different medical applications, including tissue engineering and drug-carries. The use of PLA in medical applications implies the evaluation of the human organism's response to the polymer inserting and to its degradation products. Consequently, within this study, we have investigated the solubility and ADMET profiles of the short oligomers (having the molecular weight lower than 3000 Da) resulting in degradation products of PLA. There is a linear decrease of the molar solubility of investigated oligomers with molecular weight. The results that are obtained also reveal that short oligomers of PLA have promising pharmacological profiles and limited toxicological effects on humans. These oligomers are predicted as potential inhibitors of the organic anion transporting peptides OATP1B1 and OATP1B3, they present minor probability to affect the androgen and glucocorticoid receptors, have a weak potential of hepatotoxicity, and may produce eye injuries. These outcomes may be used to guide or to supplement in vitro and/or in vivo toxicity tests such as to enhance the biodegradation properties of the biopolymer.