RESUMO
Nutrient scarcity is a frequent adverse condition that organisms face during their development. This condition may lead to long-lasting effects on the metabolism and behaviour of adults due to developmental epigenetic modifications. Here, we show that reducing nutrient availability during larval development affects adult spontaneous activity and sleep behaviour, together with changes in gene expression and epigenetic marks in the mushroom bodies (MBs). We found that open chromatin regions map to 100 of 241 transcriptionally upregulated genes in the adult MBs, these new opening zones are preferentially located in regulatory zones such as promoter-TSS and introns. Importantly, opened chromatin at the Dopamine 1-like receptor 2 regulatory zones correlate with increased expression. In consequence, adult administration of a dopamine antagonist reverses increased spontaneous activity and diminished sleep time observed in response to early-life nutrient restriction. In comparison, reducing dop1R2 expression in MBs also ameliorates these effects, albeit to a lesser degree. These results lead to the conclusion that increased dopamine signalling in the MBs of flies reared in a poor nutritional environment underlies the behavioural changes observed due to this condition during development.
Assuntos
Dopamina , Drosophila , Animais , Drosophila/genética , Larva/genética , Dieta , Encéfalo , Cromatina/genética , Epigênese Genética , NutrientesRESUMO
COVID-19 pandemic created a global shortage of medical protective equipment. Here, we considered ozone (O3) a disinfectant alternative due to its potent oxidative activity against biological macromolecules. The O3 decontamination assays were done using SARS-CoV-2 obtained from patients to produce artificial contamination of N95 masks and biosecurity gowns. The quantification of SARS-CoV-2 was performed before and after exposing the samples to different ozone gas concentrations for times between 5 and 30 min. Viral loads as a function of the O3 exposure time were estimated from the data obtained by the RT-PCR technique. The genetic material of the virus was no longer detected for any tested concentrations after 15 min of O3 exposure, which means a disinfection Concentration-Time above 144 ppm min. Vibrational spectroscopies were used to follow the modifications of the polymeric fibers after the O3 treatment. The results indicate that the N95 masks could be safely reused after decontamination with treatments of 15 min at the established O3 doses for a maximum of 6 cycles.
RESUMO
Environmental changes have been associated with natural climatic variability or human activity. Water resources management is, perhaps, the most drastic change observed in the coastal environment. However, external forcings such as the El Niño event have important implications in the global and regional hydrological balance. These environmental changes have an impact on the density and biomass of the ichthyofauna in the Terminos Lagoon (TL) for the past 30 years, presumably, associated with variations in the temperature and surface salinity of the sea. Therefore, in the present study, δ18O was quantified in otoliths of two important species due to their dominance: Stellifer lanceolatus and Eucinostomus gula, and to understand the environmental changes reflected in both species. The δ18O was analyzed in otoliths of these two species captured in 1998/1997, 2006/2007 and 2016/2017 and were compared with in situ temperature and salinity data. Sea surface temperature and salinity increased by 2 °C and 9, respectively, between 1997 and 2017. Stellifer lanceolatus δ18O values was in isotopic equilibrium with seawater calcite; while, E. gula is not in isotopic equilibrium. The δ18O of S. lanceolatus and E. gula varied significantly with the increase in salinity (R2 = 0.8987 and R2 = -0.2964) and not with the sea surface temperature. S. lanceolatus is an excellent bioindicator of changes in sea surface salinity in this region of the Gulf of Mexico.
Assuntos
Membrana dos Otólitos , Água do Mar , Animais , Golfo do México , Humanos , México , SalinidadeRESUMO
Background New-generation drug-eluting stents (DES) have mostly been investigated in head-to-head non-inferiority trials against early-generation DES and have typically shown similar efficacy and superior safety. How the safety profile of new-generation DES compares with that of bare-metal stents (BMS) is less clear.Methods We did an individual patient data meta-analysis of randomized clinical trials to compare outcomes after implantation of new-generation DES or BMS among patients undergoing percutaneous coronary intervention. The primary outcome was the composite of cardiac death or myocardial infarction. Data were pooled in a one-stage random-effects meta-analysis and examined at maximum follow-up and a 1-year landmark. Risk estimates are reported as hazard ratios (HRs) with 95% CIs. This study is registered in PROSPERO, number CRD42017060520.Findings We obtained individual data for 26 616 patients in 20 randomized trials. Mean follow-up was 3·2 (SD 1·8) years. The risk of the primary outcome was reduced in DES recipients compared with BMS recipients (HR 0·84, 95% CI 0·780·90, p<0·001) owing to a reduced risk of myocardial infarction (0·79, 0·710·88, p<0·001) and a possible slight but non-significant cardiac mortality benefit (0·89, 0·781·01, p=0·075). All-cause death was unaffected (HR with DES 0·96, 95% CI 0·881·05, p=0·358), but risk was lowered for definite stent thrombosis (0·63, 0·500·80, p<0·001) and target-vessel revascularization (0·55, 0·500·60, p<0·001). We saw a time-dependent treatment effect, with DES being associated with lower risk of the primary outcome than BMS up to 1 year after placement. While the effect was maintained in the longer term, there was no further divergence from BMS after 1 year. Interpretation The performance of new-generation DES in the first year after implantation means that BMS should no longer be considered the gold standard for safety. Further development of DES technology should target improvements in clinical outcomes beyond 1 year. (AU)
Assuntos
Angioplastia Coronária com Balão , Stents Metálicos AutoexpansíveisRESUMO
Mycoplasma ovis is a small, pleiotropic bacterium, which parasitizes the external surface of erythrocytes of several species of artiodactyl mammals, especially sheep and goats. We here report an outbreak of ovine mycoplasmosis in a sheep flock of a private ranch (Universidad Veracruzana) in Veracruz, Mexico. For the identification of Mycoplasma and other hemoparasitic bacterial agents, we stained blood smears with the DiffQuick® technique and additionally amplified several fragments of 16S rDNA gene. We detected the presence of morulas in erythrocytes from 30 sick female adult sheep, and found Mycoplasma ovis DNA in all of them. Furthermore, three of these animals also tested positive for Anaplasma ovis. Our findings represent the first record of M. ovis and A. ovis in an outbreak of hemolytic anemia in a sheep flock, leading to severe livestock loss in a ranch of Mexico. This study highlights the importance of establishing an active surveillance of both pathogens in the country.
Assuntos
Anemia Hemolítica/veterinária , Infecções por Mycoplasma/veterinária , Mycoplasma/isolamento & purificação , Doenças dos Ovinos/microbiologia , Anaplasma ovis/isolamento & purificação , Anemia Hemolítica/epidemiologia , Anemia Hemolítica/microbiologia , Animais , Surtos de Doenças/veterinária , Eritrócitos , Feminino , Gado , México , Mycoplasma/genética , Infecções por Mycoplasma/epidemiologia , Ovinos , Doenças dos Ovinos/epidemiologiaRESUMO
A molecularly imprinted polymer was developed and evaluated for selective determination of metronidazole (MNZ) in wastewater. This was achieved by using sodium methacrylate as monomer, toluene as porogen, ethylene glycol dimethacrylate as crosslinker, azobisisobutyronitrile as initiator and metronidazole as template molecule to generate the selectivity of the polymer for the compound, as well as non-imprinted polymers were synthesized. Two different polymerization approaches were used, bulk and emulsion and the polymers obtained by emulsion presented higher retention percentages the MIP 2-M presented the higher retention (83%). The performed method, was validated in fortified water, showing linearity from 10 up to 1000 ng/mL; limit of detection and quantification for compound were between 3 and 10 ng/mL, respectively. Finally, the method was applied in samples of a wastewater treatment plant in the city of San Luis Potosí, México, and the concentrations of MNZ in these samples were 84.1-114 ng/mL.
Assuntos
Metronidazol/análise , Impressão Molecular/métodos , Ácidos Polimetacrílicos/síntese química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Limite de Detecção , Metacrilatos/química , México , Nitrilas/química , Ácidos Polimetacrílicos/química , Propriedades de Superfície , Tolueno/químicaRESUMO
Single-walled carbon nanotubes (SWCNTs) are used in biological systems with impact in biomedicine in order to improve diagnostics and treatment of diseases. However, their effects upon the vascular system, are not fully understood. Endothelium and smooth muscle cells (SMC) communicate through release of vasoactive factors as nitric oxide (NO) to maintain vascular tone. The aim of this study was to evaluate the effect of SWCNTs on vascular tone using isolated rat aortic rings, which were exposed to SWCNTs (0.1, 1 and 10 µg/mL) in presence and absence of endothelium. SWCNTs induced vasodilation in both conditions, indicating that this effect was independent on endothelium; moreover that vasodilation was NO-independent, since its blockage with L-NAME did not modify the observed effect. Together, these results indicate that SWCNTs induce vasodilation in the macrovasculature, may be through a direct interaction with SMC rather than endothelium independent of NO production. Further investigation is required to fully understand the mechanisms of action and mediators involved in the signaling pathway induced by SWCNTs on the vascular system.
Assuntos
Nanotubos de Carbono/toxicidade , Vasodilatação/efeitos dos fármacos , Animais , Aorta Torácica/efeitos dos fármacos , Endotélio Vascular/fisiologia , Técnicas In Vitro , Masculino , Tono Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Óxido Nítrico/metabolismo , Ratos , Ratos WistarRESUMO
This paper presents a new unsupervised image segmentation method based on particle swarm optimization and scaled active contours with shape prior. The proposed method uses particle swarm optimization over a polar coordinate system to perform the segmentation task, increasing the searching capability on medical images with respect to different interactive segmentation techniques. This method is used to segment the human heart and ventricular areas from datasets of computed tomography and magnetic resonance images, where the shape prior is acquired by cardiologists, and it is utilized as the initial active contour. Moreover, to assess the performance of the cardiac medical image segmentations obtained by the proposed method and by the interactive techniques regarding the regions delineated by experts, a set of validation metrics has been adopted. The experimental results are promising and suggest that the proposed method is capable of segmenting human heart and ventricular areas accurately, which can significantly help cardiologists in clinical decision support.
Assuntos
Algoritmos , Coração/anatomia & histologia , Coração/diagnóstico por imagem , Modelos Cardiovasculares , Reconhecimento Automatizado de Padrão/estatística & dados numéricos , Inteligência Artificial , Sistemas de Apoio a Decisões Clínicas , Humanos , Imageamento por Ressonância Magnética/estatística & dados numéricos , Modelos Estatísticos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/estatística & dados numéricosRESUMO
This paper presents a novel image segmentation method based on multiple active contours driven by particle swarm optimization (MACPSO). The proposed method uses particle swarm optimization over a polar coordinate system to increase the energy-minimizing capability with respect to the traditional active contour model. In the first stage, to evaluate the robustness of the proposed method, a set of synthetic images containing objects with several concavities and Gaussian noise is presented. Subsequently, MACPSO is used to segment the human heart and the human left ventricle from datasets of sequential computed tomography and magnetic resonance images, respectively. Finally, to assess the performance of the medical image segmentations with respect to regions outlined by experts and by the graph cut method objectively and quantifiably, a set of distance and similarity metrics has been adopted. The experimental results demonstrate that MACPSO outperforms the traditional active contour model in terms of segmentation accuracy and stability.
Assuntos
Coração/anatomia & histologia , Interpretação de Imagem Assistida por Computador/métodos , Modelos Cardiovasculares , Biologia Computacional , Bases de Dados Factuais , Coração/diagnóstico por imagem , Ventrículos do Coração/anatomia & histologia , Ventrículos do Coração/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética/estatística & dados numéricos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/estatística & dados numéricosRESUMO
Ribosome biogenesis is a pre-requisite for cell growth and proliferation; it is however, a highly regulated process that consumes a great quantity of energy. It requires the coordinated production of rRNA, ribosomal proteins and non-ribosomal factors which participate in the processing and mobilization of the new ribosomes. Ribosome biogenesis has been studied in yeast and animals; however, there is little information about this process in plants. The objective of the present work was to study ribosome biogenesis in maize seeds during germination, a stage characterized for its fast growth, and the effect of insulin in this process. Insulin has been reported to accelerate germination and to induce seedling growth. It was observed that among the first events reactivated just after 3 h of imbibition are the rDNA transcription and the pre-rRNA processing and that insulin stimulates both of them (40-230%). The transcript of nucleolin, a protein which regulates rDNA transcription and pre-rRNA processing, is among the messages stored in quiescent dry seeds and it is mobilized into the polysomal fraction during the first hours of imbibition (6 h). In contrast, de novo ribosomal protein synthesis was low during the first hours of imbibition (3 and 6 h) increasing by 60 times in later stages (24 h). Insulin increased this synthesis (75%) at 24 h of imbibition; however, not all ribosomal proteins were similarly regulated. In this regard, an increase in RPS6 and RPL7 protein levels was observed, whereas RPL3 protein levels did not change even though its transcription was induced. Results show that ribosome biogenesis in the first stages of imbibition is carried out with newly synthesized rRNA and ribosomal proteins translated from stored mRNA.
Assuntos
DNA Ribossômico/genética , Regulação da Expressão Gênica de Plantas , Germinação/genética , Ribossomos/genética , Sementes/genética , Zea mays/genética , DNA Ribossômico/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Insulina/farmacologia , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Processamento Pós-Transcricional do RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , Ribossomos/efeitos dos fármacos , Ribossomos/metabolismo , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Fatores de Tempo , Transcrição Gênica , Zea mays/efeitos dos fármacos , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo , NucleolinaRESUMO
OBJECTIVE: To assess the carpal tunnel release technique with minimal incisions, blindly, based on the portals of Chow's endoscopic technique in fresh cadaver models. MATERIAL AND METHODS: From January 2007 to June 2009, 23 carpal tunnel releases were performed in fresh cadavers, using Chow's endoscopic portals. A malleable retractor and a fluted probe were introduced and the transverse carpal ligament was released with a retrograde scalpel from distal to proximal. We then meticulously dissected the palmar region and the anterior aspect of the forearm under magnification. We recorded the possible injuries to neurovascular and tendinous structures and whether the ligament release had been complete or incomplete, as well as the anatomical variants found. All the procedures were performed by the first author. RESULTS: 21 complete transverse carpal ligament releases were performed (91.3%). In two specimens the release of the thenar-hypothenar fascia was incomplete. We found the type I Lanz anatomical variant in one specimen and the type III in two. No associated neurovascular or tendinous injuries were reported. FINAL REMARKS: Transverse carpal ligament blind release with minimal incisions should be taken with reservations. With proper training it may be a practical and low cost procedure for the treatment of carpal tunnel syn- drome in our hospital setting. It may be performed quickly, with minimal scars and may decrease the recovery time and the loss of grip strength.
Assuntos
Síndrome do Túnel Carpal/cirurgia , Cadáver , Humanos , Procedimentos Ortopédicos/métodosRESUMO
Three lignans and four flavonoids were isolated and characterized from Larrea tridentata and compounds were tested against 16 bacterial species/strains. Results showed that: dihydroguaiaretic acid (1) had activity towards methicillin resistant (MR) Staphylococcus aureus (minimum inhibitory concentration (MIC) 50 µg/mL) and multidrug-resistant (MDR) strains of Mycobacterium tuberculosis (MIC 12.5-50 µg/mL); 4-epi-larreatricin (2) was active against Enterobacter cloacae (MIC 12.5 µg/mL), as well as sensitive (MIC 50 µg/mL) and MDR strains of M. tuberculosis (MIC 25 µg/mL). 3'-Demethoxy-6-O-demethylisoguaiacin (3) displayed activity against sensitive and resistant S. aureus (MIC 25 µg/mL), Enterococcus faecalis (MIC 12.5 µg/mL), Escherichia coli (MIC 50 µg/mL), E. cloacae (MIC 12.5 µg/mL) and MDR strains of M. tuberculosis (MIC 12.5 µg/mL). 5,4'-Dihydroxy-3,7,8,3'-tetramethoxyflavone (4) and 5,4'-dihydroxy-3,7,8-trimethoxyflavone (5) were active against M. tuberculosis MDR strains having MIC values of 25 and 25-50 µg/mL, respectively, while 5,4'-dihydroxy-7-methoxyflavone (6) was active against S. aureus (MIC 50 µg/mL) and E. faecalis (MIC 50 µg/mL). We concluded that lignan 3 is the main compound responsible for the antibacterial activity of L. tridentata. Lignans 1 and 2 as well as flavonoid 6 contribute with some degree of antibacterial activity. On the other hand, compounds 1, 2, 3, 4 and 5 contributed to the antimycobacterial activity found in L. tridentata.
Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Flavonoides/farmacologia , Larrea/química , Lignanas/farmacologia , Flavonoides/isolamento & purificação , Lignanas/isolamento & purificação , Testes de Sensibilidade Microbiana , Extratos Vegetais/farmacologia , Folhas de Planta/químicaRESUMO
The degradation of the Acid Yellow 36 (AY36) azo dye is studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) using a recirculation flow plant with an undivided cell containing a boron-doped diamond anode and an air-diffusion cathode for H2O2 electrogeneration, coupled with a solar photoreactor. A solution of 2.5L with 108 mg L⻹ of the dye and 0.5 mM Fe²(+) at pH 3.0 was comparatively treated at constant current. Hydroxyl radicals formed from Fenton's reaction and at the anode surface are the main oxidants. Total mineralization is almost achieved in SPEF, while EF yields poor TOC removal. Both processes are accelerated with increasing current. AY36 decays with similar rate in EF and SPEF following a pseudo first-order reaction, but the solution is more slowly decolorized because of the formation of conjugated byproducts. NH4(+) ion is released in SPEF, while NO3â» ion is mainly lost in EF. Tartronic, maleic, fumaric, oxalic, formic and oxamic acids are detected as generated carboxylic acids. Fe(III)-oxalate complexes are largely accumulated in EF and their quick photodecomposition in SPEF explains its higher oxidation power. The SPEF method yields greater current efficiency and lower energy cost as current decreases, and then it is more viable at low currents.
Assuntos
Compostos Azo/química , Corantes/química , Técnicas Eletroquímicas/métodos , Compostos Férricos/química , Boro/química , Ácidos Carboxílicos/química , Diamante/química , Eletrodos , Peróxido de Hidrogênio , Ferro , Cinética , Nitratos/análise , Oxirredução , Processos Fotoquímicos , Compostos de Amônio Quaternário/química , Luz SolarRESUMO
This work shows preliminary results on the electrochemical oxidation process (EOP) using boron-doped diamond (BDD) electrode for acidic yellow 36 oxidation, a common azo dye used in textile industry. The study is centred in the synergetic effect of ferrous ions and hydroxyl free radicals for improving discoloration of azo dye. The assays were carried out in a typical glass cell under potentiostatic conditions. On experimental conditions, the EOP was able to partially remove the dye from the reaction mixture. The reaction rate increased significantly by addition of Fe(2+) (1mM as ferrous sulphate) to the system and by (assumed) generation of ferrate ion [Fe(VI)] over BDD electrode. Ferrate is considered as a highly oxidizing reagent capable of removing the colorant from the reaction mixture, in synergistic action with the hydroxyl radicals produced on the BDD surface. Further increases in the Fe(2+) concentration lead to depletion of the reaction rate probably due to the hydroxyl radical scavenging effect of Fe(2+) excess in the system.
Assuntos
Compostos Azo/química , Corantes/química , Técnicas Eletroquímicas , Compostos Ferrosos/química , Boro , Diamante , Eletrodos , Radical Hidroxila , Purificação da Água/métodosRESUMO
Thermal analysis of indomethacin alpha and gamma polymorphs presents a temperature transition at 429.2 and 435.8 K, respectively, although with X-ray diffraction or near infra-red spectroscopy phase transformations were not registered. DSC method for the indomethacin amorphous solid shows an endothermic event; however, the conformational analysis at higher temperature shows a rotational change which may explain such endothermic peak. By heating the gamma polymorph at 483 K (210 degrees C) for 30 min and then quenching into liquid nitrogen the amorphous solid was obtained. The alpha form shows the highest intrinsic dissolution rate, while the lowest rate was for the amorphous indomethacin. Theoretical calculations (ab initio, Hartree-Fock and density functional theory, DFT) indicate that the double interaction is responsible for the observed difference in solubility.
Assuntos
Indometacina/química , Cristalização , Ligação de Hidrogênio , Conformação Molecular , Solubilidade , Espectroscopia de Luz Próxima ao Infravermelho , Temperatura de Transição , Difração de Raios XRESUMO
Water-soluble extracts from Mexican oregano (Lippia graveolens) were incorporated into soy protein isolate (SPI) films. Water vapor permeability, mechanical properties, and antioxidant ability were evaluated. All the extracts were capable of scavenging DPPH radicals in a concentration-dependent fashion; the IC50 values were obtained. Oregano extracts were incorporated into SPI films plasticized with sorbitol, glycerol, and glycerol-sorbitol 1:1. The addition of the extracts resulted in an increase in the water vapor permeability values and provided a dark reddish film appearance. Changes in tensile strength as well as elongation values were observed. The oregano SPI films exhibited antioxidant properties in a concentration-dependent fashion.
Assuntos
Biofilmes/efeitos dos fármacos , Embalagem de Alimentos/métodos , Origanum/química , Proteínas de Soja/química , Água/metabolismo , Antioxidantes/análise , Antioxidantes/metabolismo , Sequestradores de Radicais Livres , Permeabilidade , Extratos Vegetais/química , Plastificantes/química , Solubilidade , Proteínas de Soja/isolamento & purificação , Vapor , Resistência à TraçãoRESUMO
El secuestro pulmonar es una masa de tejido pulmonar anormal que no se comunica con el árbol traqueobronquial y es irrigada por una arteria sistemica anomala. Tiene origen congenito y se presenta en dos variedades: intralobar y extralobar. Se revisa la literatura existente sobre esta rara malformacion pulmonar.
Assuntos
Sequestro BroncopulmonarRESUMO
Dp71 is a member of the dystrophin family and the most abundant dmd gene product in the brain. In the present study, we focused on a short dystrophin transcript named Dp71f, which is alternatively spliced when exon 78 is absent The topographic localization of this protein in the encephalon has not been properly described yet, nor its cellular or subcellular localization, and even less its functions. Dp71f was found to be a cytoplasmic 70 kDa protein and localized in all encephalon regions studied. Double labeling using specific markers for various cell types confirmed Dp71f distribution in the cytoplasm of all cell types studied. Labeling was more conspicuous near the nucleus and diminished towards the periphery of cells. In some cases, we observed cells that were positive for actin and Dp71f in regions corresponding to lamellipodia-like structures. Dp71f and Dp71d isoforms were differently distributed. Our study is the first specific and unambiguous description of the topography and cellular localization patterns of Dp71f in brain, suggesting that Dp71f is a ubiquitous protein.
Assuntos
Química Encefálica , Encéfalo/metabolismo , Distrofina/análise , Animais , Western Blotting , Células Cultivadas , Distrofina/análogos & derivados , Microscopia Imunoeletrônica , Isoformas de Proteínas/análise , Ratos , Frações Subcelulares/metabolismo , Extratos de Tecidos/químicaRESUMO
A reversed-phase liquid chromatographic method was applied to study the stability of thimerosal in Cuban recombinant hepatitis B vaccine samples stored under different temperature conditions. Salicylic acid was used as internal standard, it allowed one to determine the thimerosal in the presence of its degradation products. Good stability of the preservative was demonstrated in vaccine samples for as long as 6 years. The same results were obtained when the vaccine samples were incubated at 37 and 45 degrees C during 30 days. The results were in compliance with the microbiological test for determining the effectiveness of antimicrobial preservative in these samples.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Vacinas contra Hepatite B/química , Timerosal/análise , Vacinas Sintéticas/química , Anti-Infecciosos/análise , CalibragemRESUMO
The ability of chromium (Cr) salts to increase metallothionein (MT) levels in rat liver, kidney and pancreas, and its relationship with the presence of toxic effects are reported here. Rats were injected subcutaneously with 0, 10, 20, 30, 40, or 50 mg K2Cr2O7/kg and sacrificed 24 h later. Total Cr accumulation followed a dose-dependent pattern, levels in kidney being higher than those in liver or pancreas, suggesting different tissue bioavailabilities and accumulation patterns. Cr(IV) administration resulted in a tissue-specific MT induction: pancreas and liver showed five- and 3.5-fold MT increases, respectively; no increase was observed in the kidney. A positive correlation was observed between zinc and MT concentrations in liver, and between total Cr and MT concentrations in pancreas. Serum alpha-amylase activity showed a dose-dependent increase starting from 20 mg/kg, whereas serum glucose levels increased at doses higher than 30 mg/kg. Serum aspartate aminotransferase and alanine aminotransferase activities were increased in a dose-dependent manner, from 20 and 30 mg/kg, respectively. Our results showed that treatment with Cr(VI) can induce MT synthesis in pancreas and suggests a subsequent binding of Cr to MT. Also, pancreas is a target organ for Cr toxicity, and the usefulness of alpha-amylase activity as a sensitive biomarker of Cr toxicity in human exposed populations merits further study.