Understanding gold toxicity in aerobically-grown Escherichia coli

BACKGROUND: There Is an emerging field to put Into practice new strategies for developing molecules with antimicrobial properties. In this line, several metals and metalloids are currently being used for these purposes, although their cellular effect(s) or target(s) in a particular organism are still unknown. Here we aimed to investigate and analyze Au3+ toxicity through a combination of biochemical and molecular approaches. RESULTS: We found that Au3+ triggers a major oxidative unbalance in Escherichia coli, characterized by decreased intracellular thiol levels, increased superoxide concentration, as well as by an augmented production of the antioxidant enzymes superoxide dismutase and catalase. Because ROS production is, in some cases, associated with metal reduction and the concomitant generation of gold-containing nanostructures (AuNS), this possibility was evaluated in vivo and in vitro. CONCLUSIONS: Au3+ is toxic for E. coli because it triggers an unbalance of the bacterium's oxidative status. This was demonstrated by using oxidative stress dyes and antioxidant chemicals as well as gene reporters, RSH concentrations and AuNS generation.

Neuroprotective Effect of Isobenzofuranones on Hydrogen Peroxide-Mediated Redox Imbalance in Primary Cultures of Hippocampal Neurons

Abstract In live organisms, there is a balance between the production of reactive oxygen species (ROS) and their neutralization. The increased level of these species leads to a condition called redox imbalance. The aim of this study was to evaluate the protective action of isobenzofuranones in primary cultures of hippocampal neurons subjected to redox imbalance. To accomplish this, MTT and LIVE/DEAD assays were initially performed. In the cultures pretreated with isobenzofuranones 1 and 2, there was a higher number of live cells when compared to that in the untreated ones. Regarding redox imbalance, there was a significant increase in the intracellular levels of ROS. The cultures pretreated with isobenzofuranones showed a reduction in ROS levels. Lipid peroxidation caused by oxidative damage was significantly reduced in the cultures pretreated with isobenzofuranones 1 and 2. Taken together, these data show the ability of isobenzofuranones 1 and 2 to significantly minimize cytotoxicity, cell death, intracellular levels of ROS and lipid peroxidation induced by redox imbalance. These results suggest that isobenzofuranones 1 and 2 represent a possible alternative therapy for the neurodegenerative disturbances that are triggered by ROS production increases.

Effect of taxifolin on oxidative gastric injury induced by celiac artery ligation in rats

Abstract Purpose: To examine the effect of taxifolin on I/R induced gastric injury in rats using biochemical and histopatholohical methods. Methods: Eighteen albino Wistar male rats equally grouped as; gastric I/R (I/R), 50 mg/kg taxifolin + gastric I/R (TAX+ I/R) and sham operation applied (SHAM). Ischemia induced for 1 hour, and reperfusion induced for 3 hours. Results: Oxidant parameters like, Malondialdehyde (MDA) and Hydroxyguanine (8-OHdG) were higher, whereas total glutathione (tGSH) was lower in the I/R group according to SHAM group, histopathological findings such as marked destruction, edema, and proliferated dilated congested blood vessels were observed severely in the I/R group, whereas there was not any pathological finding except mild dilated congested blood vessels in the TAX+ I/R group. Conclusion: The taxifolin can be clinically beneficial in the treatment of gastric injury due to I/R procedure.

Evaluation of redox profiles in exogenous subclinical hyperthyroidism at two different levels of TSH suppression

ABSTRACT Objective: Evaluate the relationship between exogenous subclinical hyperthyroidism and oxidative stress through the analysis of the redox profile of patients with subclinical hyperthyroidism exogenous (SCH) grade I (TSH = 0.1 to 0.4 IU/mL) and grade II (TSH < 0.1 IU/mL). Subjects and methods: We analyzed 46 patients with SCH due to the use of TSH suppressive therapy with LT4 after total thyroidectomy along with 6 control euthyroid individuals (3M and 3W). Patients were divided into two groups, G1 with TSH ≥ 0.1-0.4 IU/mL (n = 25; and 7M 14W) and G2 with TSH < 0.1 IU/mL (n = 25; and 4M 21W). Venous blood samples were collected to measure the levels of markers for oxidative damage (TBARS, FOX and protein carbonylation), muscle and liver damage (CK, AST, ALT, GGT) and antioxidants (GSH, GSSG and catalase). Results: Individuals in G2 showed a GSH/GSSG ratio ~ 30% greater than those in G1 (p = 0.004) and a catalase activity that was 4 times higher (p = 0.005). For lipid peroxidation, the levels measured in G2 were higher than both control and G1 (p = 0.05). No differences were observed for both protein carbonyl markers. G1 and G2 presented with greater indications of cell injury markers than the control group. Conclusion: TSH suppression therapy with LT4 that results in subclinical hyperthyroidism can cause a redox imbalance. The greater antioxidant capacity observed in the more suppressed group was not sufficient to avoid lipid peroxidation and cellular damage.

Effect of ozone oxidative preconditioning on inflammation and oxidative stress injury in rat model of renal transplantation

Abstract Purpose: To investigate the effect of ozone oxidative preconditioning (OzoneOP) on inflammation and oxidative stress injury in rat model of renal transplantation. Methods: Thirty six male Sprague Dawley (SD) rats were randomly divided into three groups. Sham group: rats were treated with opening and closing abdomen. Kidney transplantation group (KT group): SD rat received the donor's left kidney derived from another SD rat. Ozone oxidative preconditioning and kidney transplantation (OOP+KT group): donor SD rats received OzoneOP treatments by transrectal insufflations before kidney transplantation. After transplantation, parameters of renal function of recipients were determined. Morphology and pathological changes of renal allograft were examined. Expression of NF-κBp65, HMGB-1 were also determined by Western-blot. Results: Compared to KT group, the morphology and pathological damages of renal allograft were less serious in OOP+KT group. Meanwhile, levels of SOD and GSH-Px of renal allograft in OOP+KT group were higher than those in KT group respectively. Western-blot showed that the expressions of NF-κBp65 and HMGB-1 in OOP+KT group were obviously less than those in KT group. Conclusion: Ozone oxidative preconditioning could attenuate the inflammatory reaction and oxidative stress injury in renal allograft, which might be related with the enhancement of anti-oxidative system and suppression of inflammatory reaction.

Treatment with Ilex paraguariensis (yerba mate) aqueous solution prevents hepatic redox imbalance, elevated triglycerides, and microsteatosis in overweight adult rats that were precociously weaned

Early weaning (EW) leads to overweight, visceral obesity, hyperleptinemia, and insulin resistance in adulthood. Treatment with Ilex paraguariensis (yerba mate) improves obesity and insulin resistance in these animals. Here, we evaluated the effects of chronic treatment with yerba mate on the redox balance and liver morphology of overweight early-weaned rats. To induce EW, we wrapped the dams with bandages to interrupt milk access during the last 3 days of lactation. Control pups (C) had free access to maternal milk for the full 21 days of lactation. On postnatal day (PN) 150, EW offspring were subdivided into the EW+YM group, which received the aqueous extract of yerba mate (1 g/kg bw by gavage once a day for 30 days) and the EW group, which received water by gavage for the same period. All rats were euthanized on PN180. The EW group showed higher bound carbonyl (a marker of total protein oxidation), higher TBARS levels (a marker of lipid peroxidation), and lower superoxide dismutase (SOD) activity in liver tissue than the C group, as well as higher triglyceride content and microsteatosis. In plasma, the EW offspring showed higher TBARS levels. One month of yerba mate treatment normalized these parameters. Thus, we have shown evidence that yerba mate improved antioxidant defenses and mitigated liver dysfunction in overweight adult rats that were weaned prematurely.

TBARS and BDNF levels in newborns exposed to crack/cocaine during pregnancy: a comparative study

Objectives: To compare levels of a marker of lipid peroxidation (thiobarbituric acid reactive substances, TBARS) and brain-derived neurotrophic factor (BDNF) in umbilical cord blood (UCB) between newborns exposed to crack/cocaine in utero (exposed newborns [EN], n=57) and non-exposed newborns (NEN, n=99), as well as in maternal peripheral blood at delivery. Methods: This was a cross-sectional study. Potential confounders, including perinatal parameters, psychopathology, and use of other substances, were assessed. Results: After adjusting for potential confounders, adjusted mean BDNF was significantly higher in EN (3.86 ng/mL, 95% confidence interval [95%CI] 2.29-5.43) than in NEN (0.85 ng/mL, 95%CI 0.47-1.23; p < 0.001; Cohen effect size: 1.12), and significantly lower in crack/cocaine mothers than in control mothers (4.03 ng/mL, 95%CI 2.87-5.18 vs. 6.67 ng/mL, 95%CI 5.60-7.74; p = 0.006). The adjusted mean TBARS level was significantly lower in EN (63.97 µM MDA, 95%CI 39.43-88.50) than NEN (177.04 µM MDA, 95%CI 140.93-213.14; p < 0.001; effect size = 0.84), with no difference between mother groups (p = 0.86). Conclusions: The changes in TBARS levels observed in EN suggest that fetuses exposed to cocaine mobilize endogenous antioxidant routes since very early stages of development. The increase in BDNF levels in EN might indicate changes in fetal development, whereas the changes in BDNF levels in mothers provide evidence of the complex metabolic processes involved in drug use during pregnancy.

Intestinal inflammatory and redox responses to the perioperative administration of teduglutide in rats

Abstract Purpose: To investigate the inflammatory and redox responses to teduglutide on an animal model of laparotomy and intestinal anastomosis. Methods: Wistar rats (n=62) were allocated into four groups: "Ileal Resection and Anastomosis" vs. "Laparotomy", each one split into "Postoperative Teduglutide Administration" vs. "No Treatment"; and euthanized at the third or the seventh day. Ileal and blood samples were recovered at the baseline and at the euthanasia. Flow cytometry was used to study the inflammatory response (IL-1α, MCP-1, TNF-α, IFN-γ and IL-4 levels), oxidative stress (cytosolic peroxides, mitochondrial reactive species, intracellular glutathione and mitochondrial membrane potential) and cellular viability and death (annexin V/propidium iodide double staining). Results: Postoperative teduglutide treatment was associated with higher cellular viability index and lower early apoptosis ratio at the seventh day; higher cytosolic peroxides level at the third day and mitochondrial overgeneration of reactive species at the seventh day; higher tissue concentration of IL-4 and lower local pro-to-anti-inflammatory cytokines ratio at the seventh day. Conclusion: Those findings suggest an intestinal pro-oxidative and anti-inflammatory influence of teduglutide on the peri-operative context with a potential interference in the intestinal anastomotic healing.

In vitro effect of N-acetyl-L-cysteine on glutathione and sulfhydryl levels in X-linked adrenoleukodystrophy patients

Introduction: Recent evidence shows that oxidative stress seems to be related with the pathophysiology of X-linked adrenoleukodystrophy (X-ALD), a neurodegenerative disorder. Methods: In the present study, the in vitro effect of N-acetyl-L-cysteine (NAC) on glutathione (GSH) and sulfhydryl levels in X-ALD patients was evaluated. Results: A significant reduction of GSH and sulfhydryl content was observed in X-ALD patients compared to the control group. Furthermore, 5 mM of NAC, in vitro, led to an increase in GSH content and sulfhydryl groups in these patients. Conclusion: These data probably indicate that an adjuvant therapy with the antioxidant NAC could improve the oxidative imbalance in X-ALD patients(AU)

Antioxidant activity and phenol content of extracts of bark, stems, and young and mature leaves from Blepharocalyx salicifolius (Kunth) O. Berg / Atividade antioxidante e teor de polifenóis de extratos de cascas (súber), caule, folhas jovens e folhas maduras de Blepharocalyx salicifolius (Kunth) O. Berg (Murta)

Abstract Phenolic compounds are a group of plant secondary metabolites known to have a variety of bioactivities, including the ability to function as antioxidants. Because of the side effects of the use of synthetic substances, the search for natural and less toxic compounds has increased significantly. This study was designed to evaluate the antioxidant activity and phenol content of hexane, ethyl acetate, and aqueous extracts of the bark (suber) and stems as well as the young and mature leaves of Blepharocalyx salicifolius. The extracts were obtained by extraction with organic solvents and subsequent fractionation by chromatographic partition coefficient. Preliminary tests for the presence of antioxidants were performed using bioautography in thin-layer chromatography. The antioxidant activity of the extracts was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, and the phenol content of the extracts was quantified using the Folin-Ciocalteu technique. The results showed that 9 of the 12 extracts evaluated displayed very strong antioxidant activity and three displayed moderate activity. Aqueous extracts of the young leaves and bark and the ethyl acetate extract of the young leaves showed the highest levels of antioxidant activity and total phenolic content (TPC). A correlation was observed between TPC and antioxidant activity index (AAI) with a correlation coefficient (r2) of 0.7999. Thus, the high phenol content of B. salicifolius extracts and its correlation with antioxidant activity provide substrates for further studies.

Resumo Os polifenóis são um grupo de metabólitos secundários vegetais que possuem uma variedade de bioatividades conhecidas, dentre elas a capacidade de funcionar como antioxidantes. Devido aos efeitos colaterais do uso excessivo de substâncias sintéticas, a busca por compostos naturais e menos tóxicos têm aumentado significativamente. Esse estudo teve por objetivo avaliar a atividade antioxidante e o teor de polifenóis dos extratos hexânicos, acetato de etila e aquosos de cascas (súber), caules, folhas jovens e folhas maduras de Blepharocalyx salicifolius. Os extratos foram obtidos por meio de extração com solventes orgânicos e subsequente fracionamento em cromatografia por coeficiente de partição. Testes preliminares da presença de compostos com atividade antioxidante foram realizados por meio de bioautografia em cromatografia de camada delgada. Os extratos foram submetidos ao teste da capacidade sequestrante do radical 2,2-difenil-1-picrilhidrazil (DPPH) para quantificação da atividade antioxidante e submetidos ao teste com o reagente de Folin-Ciocalteu para quantificação dos polifenóis. Os resultados mostraram que dos 12 extratos avaliados, 9 apresentaram atividade antioxidante muito forte e 3 atividade moderada. Os extratos aquosos de folhas jovens e cascas e o extrato acetato de etila de folhas jovens apresentaram os maiores índices de atividade antioxidante e teor de polifenóis (TPC). A correlação entre TPC e o índice de atividade antioxidante (AAI) observada foi de r2 = 0,7999. Dessa forma, ficou evidenciado o elevado teor de polifenóis e sua correlação com a atividade antioxidante nos extratos de B. salicifolius, fornecendo subsídios para novos estudos.

Efecto del metronidazol suplementado con hidroquinona en la adherencia de Lactobacillus acidophilus en células vaginales ovinas / Effect of metronidazole supplemented with hydroquinone on the adhesion of Lactobacillus acidophilus in ovine vaginal cells

This work demonstrates that the addition of metronidazole together with a ubiquitous quinone compound reduces adherence of Lactobacillus acidophilus to ovine vaginal cells. Spectrophotometric and voltammetric studies have shown that neoformed compounds were observed in these systems; there were also changes in their electroactive composition, and the oxidant status had a significantly higher value compared to the control (p < 0.05). Based on reduction potential (E; mV), the distribution of electroactive compound concentrations suggests that the compounds with low reduction potential induce this behavior, which would indicate that the addition of metronidazole with a ubiquitous quinone compound to the vaginal system might increase the reductive capacity of these systems. This work shows that the study of behavior and fluctuations of the redox compounds that compose the vaginal environment, in terms of concentration and species of redox molecules, must be hierarchized in order to better understand the early stages of colonization by microorganisms.

Este trabajo demuestra que la incorporación de metronidazol conjuntamente con un compuesto quinónico ubicuo disminuye la adherencia de Lactobacillus acidophilus a células vaginales ovinas. Los estudios espectrofotométricos y voltamétricos mostraron que en estos sistemas aparecieron compuestos neoformados y que hubo modificaciones en la composición electroactiva; asimismo, el estatus oxidante presentó un valor significativamente superior con respecto al control (p < 0,05). Según los potenciales de reducción (E; mV), la distribución de las concentraciones de los compuestos electroactivos muestra que los compuestos con bajos potenciales de reducción inducen este comportamiento. Esto indicaría que la incorporación de esta mezcla al sistema vaginal aumentaría su capacidad reductora. El trabajo muestra que el estudio del comportamiento y las fluctuaciones de los compuestos redox que componen el ambiente vaginal, en términos de concentración y especies moleculares, debe ser jerarquizado para comprender mejor las primeras etapas de la colonización de este ambiente por parte de los microorganismos.

El impacto de la hidroquinona usada como un modelo de efector redox sobre la desnitrificación potencial, la actividad microbiana y las condiciones redox de un suelo cultivable / Impact of hydroquinone used as a redox effector model on potential denitrification, microbial activity and redox condition of a cultivable soil

In this microcosm study, we analyzed the effect produced by hydroquinone on the expression of soil biological denitrification, in relation to the redox state of the soil, both in terms of intensity factor (Eh′) and capacity factor (amount of oxidized or reduced compounds). The supplementation of an Argiudoll soil with hydroquinone decreased the soil apparent reduction potential (Eh′) and soil dehydrogenase activity (formazan production from tetrazolium chloride reduction; redox capacity factor), the relationship between both factors being highly significative, r = 0.99 (p < 0.001). The bacterial population (measured by colony forming units) increased, and the production of N2O was greater (p < 0.001) at 200 and 400 μg/g dry soil doses. Furthermore, there was an inverse relationship between soil dehydrogenase activity and the number of bacteria (r = −0.82; p < 0.05), increased denitrification activity and changes in the CO2/N2O ratio value. These results suggest that hydroquinone at supplemented doses modified the soil redox state and the functional structure of the microbial population. Acetate supplementation on soil with hydroquinone, to ensure the availability of an energy source for microbial development, confirmed the tendency of the results obtained with the supplementation of hydroquinone alone. The differences observed at increased doses of hydroquinone might be explained by differences on the hydroquinone redox species between treatments.

En este trabajo estudiamos, en condiciones de microcosmos, el efecto que produce la hidroquinona sobre la expresión de la desnitrificación en relación con el estado de óxido-reducción del suelo, en términos de factor de intensidad (Eh′) y de factor de capacidad (cantidad de compuestos oxidados o reducidos). La suplementación de un suelo argiudol con hidroquinona disminuyó el potencial de reducción aparente (Eh′) y la actividad deshidrogenasa (producción de formazán a partir de la reducción de cloruro de tetrazolio; factor de capacidad redox), la relación entre ambos factores fue altamente significativa, r = 0,99 (p < 0,001). La población bacteriana heterotrófica (medida como unidades formadoras de colonias) aumentó y la producción de N2O fue mayor (p < 0,001) con las dosis de 200 y 400 μg/g de suelo seco. Además se observó una relación inversa entre la producción de formazán y el número de bacterias (r = −0,82; p < 0,05), la actividad desnitrificadora aumentó y se produjeron cambios en el valor del cociente CO2/N2O. Estos resultados sugieren que la hidroquinona, en las dosis empleadas, modificó el estado redox del suelo y la estructura funcional de la población microbiana. La suplementación con acetato en el suelo con hidroquinona, a fin de asegurar la disponibilidad de una fuente de energía para el desarrollo bacteriano, confirmó la tendencia de los resultados obtenidos con la suplementación con hidroquinona solamente. Las diferencias observadas con el incremento en la dosis de hidroquinona podrían explicarse por las diferencias sobre las especies redox de la hidroquinona entre los tratamientos.

Adherence to standard precautions from the standpoint of the Health Belief Model: the practice of recapping needles / Adesão às precauções padrão sob o prisma do Modelo de Crenças em Saúde: a prática de reencapar agulhas

The aim of this study was to applythe Health Belief Model to explain the adherence to the recommendation not to recap needles by dentists and dental assistants of the public health system in a municipality in the State of São Paulo. A questionnaire validated and adapted for the oral health area was used, which included variables related to the frequency of recapping and health beliefs using Likert-type scales. The relationship between beliefs and adherence to the recommendation not to recap needles was obtained by regression analysis. Of all the professionals in this study (n=79), the majority (83.5%) reported recapping needles at least once in the last month. Through regression analysis, it was observed that the relationship between the beliefs described by the model and the attitude whether or not to follow the recommendation not to recap needles was explained by a lower perception of psychological barriers and a greater perception of stimuli not to recap needles. The conclusion reached is that the acceptance of recommendations to prevent working accidents with biological material was explained by some dimensions of the Health Belief Model, enabling discussion about reformulation of training offered to professionals of the public health system.

Objetivou-se neste estudo aplicar o Modelo de Crenças em Saúde a fim de explicar a adesão à recomendação de não reencapar agulhas por cirurgiões-dentistas e auxiliares de saúde bucal da rede pública de um município paulista. Utilizou-se um questionário validado e adaptado para a área de saúde bucal, que contemplava variáveis relativas à frequência do reencape e crenças em saúde, por meio de escalas tipo Likert. A relação entre as crenças e a adesão à recomendação de não reencapar agulhas foi obtida por meio da análise de regressão. Da amostra de profissionais obtida por adesão ao estudo (n = 79), a maioria (83,5%) relatou ter reencapado agulhas pelo menos alguma vez no último mês. Por meio da análise de regressão, foi observado que a relação entre as crenças descritas pelo modelo e a atitude de aderir ou não à recomendação de não reencapar agulhas foi explicada por uma menor percepção de barreiras psicológicas e por uma maior percepção de estímulos para não reencapar agulhas. Conclui-se que a aceitação das recomendações para prevenir acidentes do trabalho com material biológico foi explicado por algumas dimensões do Modelo de Crenças em Saúde, possibilitando a discussão sobre a reformulação de capacitações oferecidas para profissionais do sistema público de saúde.

Novo papel da proteína XPC na regulação dos complexos da cadeia de transporte de elétrons e desequilíbrio redox / New role of XPC protein in regulating the electron transport chain complexes and redox unbalance

Espécies reativas de oxigênio (EROs) são normalmente e continuamente geradas em mitocôndrias, majoritariamente na cadeia de transporte de elétrons (CTE). Harman (1956, 1972 e 1992) teorizou que os radicais livres gerados nas mitocôndrias seriam a principal causa do envelhecimento. De fato, durante o envelhecimento é observado um desequilíbrio entre formação e remoção de EROs, que resulta em estresse redox. Essa condição favorece a formação de lesões oxidadas no DNA, acarretando em mutagênese ou morte celular. Diversos mecanismos moleculares cooperam para o reparo de DNA. Duas vias de reparo de DNA lidam com a maioria das lesões: o reparo por excisão de base (BER) e o reparo por excisão de nucleotídeos (NER). A via BER corrige pequenas modificações de bases que surgem de reações de desaminação, alquilação e oxidação. A via NER é mais versátil, reconhecendo lesões que distorcem a dupla hélice de DNA, como danos induzidos por luz UV e adutos volumos. Pacientes xeroderma pigmentoso (XP-A a XP-G) herdam mutações em um de sete genes que codificam proteínas envolvidas na via NER, ou em um gene que codifica uma polimerase translesão (XP-V). A doença é caracterizada por fotosensibilidade e incidência elevada de neoplasias cutâneas. A proteína XPC atua na etapa de reconhecimento da lesão de DNA na subvia de reparo global do genoma (GG-NER), e sua mutação dá origem aos sintomas clássicos de XP. Novas funções de XPC foram recentemente descritas: i) atuando como cofator na via BER auxiliando as DNA glicosilases OGG1, TDG e SMUG; ii) atuando como cofator transcricional de elementos responsivos a Oct4/Sox2, RXR e PPARα; e iii) na adaptação metabólica na transformação de queratinócitos. Então, propusemo-nos a investigar as relações entre XPC e a manutenção da integridade do DNA mitocondrial, a sensibilidade celular a estresse redox mitocondrial e possíveis alterações bioenergéticas e redox. Para tal, padronizamos um ensaio in vitro de cinética de incisão em DNA plasmidial a fim de investigarmos o possível papel de XPC no reparo de lesões oxidadas em mtDNA. Porém, nossos dados revelaram que XPC não se encontra em mitocôndrias. Apesar disso, células XP-C são mais sensíveis ao tratamento com azul de metileno (AM), antimicina A (AA) e rotenona (ROT), que geram estresse redox mitocondrial. A sensibilidade à AA foi completamente revertida em células corrigidas. Células XP-C apresentaram alterações quanto ao uso dos complexos mitocondriais, com diminuição da taxa de consumo de oxigênio (OCR) via complexo I e um aumento da OCR via complexo II, dependente da presença de XPC. Ademais, a linhagem XP-C apresentou um desequilíbrio redox mitocondrial com maior produção de EROs e menor atividade de GPx. O DNA mitocondrial de células XP-C apresentou níveis elevados de lesão e deleção, que no entanto não retornaram aos níveis encontrados em células selvagens na linhagem XP-C corrigida. Observamos uma acentuada diminuição da expressão de PPARGC1A, um importante regulador de biogênese mitocondrial. Contudo, não foi possível determinar o mecanismo de supressão da expressão de PPARGC1A. Por fim, identificamos que o tipo de mutação em XPC pode estar associado a expressão de PPARGC1A. Esse estudo abre novas possibilidade na investigação do papel de proteína XPC, à parte da instabilidade genômica, na adaptação metabólica e desequilíbrio redox em direção da progressão tumoral

Mitochondria continuously produce reactive oxygen species (ROS), mainly at the electron transport chain. Harman (1956, 1972 e 1992) proposed that normal aging is driven by increased mitochondrially generated free radicals. Indeed, during the course of aging there is an increased imbalance between formation and removal of ROS, leading to redox stress. This condition favours the formation of oxidized DNA lesions, given rise to mutations and cell death. Several molecular mechanisms cooperates to repair the DNA. Two DNA repair pathways deal with the majority of lesions: base excision repair (BER) and nucleotide excision repair (NER). The BER pathway corrects small base modifications that arise from deamination, alkylation and oxidation reactions. The NER pathway is more versitile, recognizing helix-distorting lesions, such as UV-induced damage and bulky adducts. Xeroderma pigmentosum (XP-A to XP-G) patients inherit mutations in one of seven protein-coding genes involved in NER pathway, or in a gene coding a translesion DNA polymerase (XP-V). Photosensitivity and a thousand-fold increased in the risk of developing cutaneous neoplasms are the main clinical features of XP. XPC protein functions in the recognition step of global genome NER (GG-NER) sub-pathway, and mutations in this gene lead to classical XP symptoms. Recently, it has been described that XPC acts: i) as a cofactor in BER pathway through functional interaction with DNA glycosylases OGG1, TDG and SMUG1; ii) as coactivator in transcription at Oct4/Sox2, RXR and PPARα responsive elements; iii) in metabolic shift during keratinocytes transformation. Thus, we sought to investigate a possible role for XPC in the maintenance of mtDNA integrity, cellular sensitivity to mitochondrial redox stress and eventual bioenergetic and redox changes. For this purpose, we established an in vitro plasmid incision assay to investigate the possible role of XPC in the repair of oxidized lesions in mitochondrial DNA. However, our data revealed that XPC did not localized in mitochondria. Nonetheless, XP-C cells are more sensitive to methylene blue, antimycin A (AA) and rotenone treatment, which induce mitochondrial redox stress. The XP-C sensitivity to AA was completely reverted in XPC-corrected cells. XP-C cells presented altered usage of mitochondrial complexes, with decreased oxygen consumption rate (OCR) via complex I and increased OCR through complex II, an XPC-dependent phenomenon. Furthermore, the XP-C cell line showed mitochondrial redox imbalance with increased ROS production and decrease GPx activity. MtDNA from XP-C cells accumulate lesions and deletions, which, however, were found at similar levels in the corrected cell line. We identified a sharp decrease in the expression of PPARGC1A, a master regulator of mitochondrial biogenesis. Nevertheless, it was not possible to determine the mechanism of suppression of PPARGC1A expression. Finally, our results suggest a possible link between the type of XPC mutation and PPARGC1A expression. This study unfolds new possible roles for XPC, aside from its established roles in genomic instability, in metabolic adaptation and redox imbalance towards tumour progression

Efecto del ácido alfa lipoico y la pirfenidona en la modulación antioxidante celular contra el daño oxidativo / Effects of alpha lipoic acid and pirfenidone on liver cells antioxidant modulation against oxidative damage

Background: Liver fibrogenic processes are related to cellular redox state. Glutathione (GSH) is the major cellular antioxidant. GSH induced activation could be related to antifibrogenic effects. Aim: To explore the association between the antifibrogenic effect and pro-antioxidant mechanisms of alpha-lipoic acid (ALA) and pirfenidone (PFD). Material and Methods: HepG2 cells and primary HSC cultures were exposed to menadione 0.1 μM (MEN) as oxidative stress inducer and treated to ALA (5 mM) or PFD (10 μM, 100 μM y 1000 μM). Results: In HSC, PFD decreased cell proliferation and the expression of COL1A1, TGF-β1, TIMP1, IL6, TNFα and MCP1 induced by MEN. Furthermore it was confirmed that ALA and PFD activate diverse antioxidants mediators, however MEN decreases this response. Then, MEN, ALA and PFD induce an antioxidant response, the first one as a response to injury and the latter two as pro-antioxidant inducers. Therefore, when cells are exposed to oxidative stress, endogenous systems activate a battery of mediators that increase the antioxidant potential. When these cells are treated with ALA and PFD, de novo formation of protective genes decreases since previous elicited protection induced in response to injury, enhance ALA and PFD effects. Conclusion: Regardless of the route of action, ALA and PFD induce the biosynthesis of antioxidants mediators which is associated with modulation of fibrogenic processes.

Apontamentos acerca da Cadeia do Ser e o lugar dos negros na filosofia natural na Europa setecentista / Notes on the Chain of Being and the place of blacks in eighteenth-century European natural philosophy

Por meio da análise de obras acadêmicas produzidas por filósofos naturais no século XVIII, pretendemos discutir algumas ideias recorrentes acerca da Grande Cadeia do Ser. Para tal, analisamos as relações entre filosofia e teologia natural no período. Reavaliamos ainda alguns elementos da Cadeia do Ser, investigando autores que discorreram sobre o tema em seus escritos. Por fim, elencamos um ponto específico das discussões setecentistas sobre a scala naturae, qual seja, as diversas e nem sempre convergentes ideias de que, a partir de características específicas, haveria diferenças entre os homens, bem como seu consequente lugar na Cadeia do Ser.

This examination of academic works produced by eighteenth-century natural philosophers discusses some recurring ideas about the Chain of Being. To this end, the article analyzes the relations between natural philosophy and theology during the period. It also re-evaluates some elements of the Chain of Being through an exploration of authors who addressed the topic in their writings. Lastly, it identifies a specific element within eighteenth-century discussions of scala naturae, to wit, the various and not always convergent ideas about whether there are differences between humans based on specific characteristics and, consequently, about the places they occupy in the chain of being.

Investigação de potenciais biomarcadores redox - um enfoque em aldeídos e seus produtos / Potential redox biomarkers investigation - focus on aldehydes and their products

As espécies reativas são associadas a processos toxicológicos e fisiopatológicos, agindo como importantes mediadores, por exemplo, na sinalização celular. Diversas classes de compostos têm sido utilizadas como possíveis biomarcadores de estresse redox, destacando-se os aldeídos α,ß-insaturados, capazes de alquilar biomoléculas como o DNA. Para evitar efeitos deletérios, estes aldeídos são detoxificados por glutationilação e posterior metabolização a derivados mercaptúricos. Contudo, avaliar o estado redox em sistemas biológicos ainda é tarefa bastante complexa, sendo a dificuldade em quantificar de forma prática e acurada os efeitos de sinalização e/ou dano molecular o maior problema dos estudos redox. Assim, o objetivo deste trabalho foi desenvolver métodos acurados e sensíveis de análise de potenciais biomarcadores de estresse redox, isto é: nucleosídeos modificados, aldeídos endógenos e exógenos, glutationa e produtos de glutationilação, e avaliá-los em sistemas modelos, celular e animal, e em humanos. A avaliação dos níveis urinários de três nucleosídeos modificados por metodologia de HPLC-MS/MS desenvolvida pelo grupo em moradores da cidade de São Paulo - região com poluição atmosférica - demonstrou aumento significativo de 1,N2-propanodGuo comparado aos moradores de região não poluída. Ademais, comprova-se pela primeira vez que células deficientes em reparo de ligações cruzadas apresentam níveis basais elevados de 1,N2-propanodGuo, em duas linhagens independentes, colocando este aduto como potencial mediador de carcinogênese em pacientes portadores de Anemia de Fanconi. Utilizando cérebro de ratos SOD1G93A (modelo de Esclerose Lateral Amiotrófica - ELA), verificou-se aumento de 50% nos níveis de 1,N2-propanodGuo e de 100% nos de 1,N6-εdAdo em fase sintomática, sugerindo influência do conteúdo lipídico cerebral, levando a comprometimento do metabolismo neuronal e morte celular. O perfil de aldeídos determinado em cérebro de ratos SOD1G93A demonstrou aumento de trans-hexa-2-enal e trans,trans-hexa-2,4-dienal em fase assintomática e de trans,trans-deca-2,4-dienal em fase sintomática, não sendo observada nenhuma alteração na medula. Conhecer estas variações permite direcionar estudos de modificações em biomoléculas, além de a metodologia per se corroborar com as áreas de análises lipidômicas. Técnicas distintas e o preparo de amostras refletiram nos níveis de glutationa reduzida (GSH) e oxidada (GSSG) relatados. A técnica de espectrometria de massas mostrou-se mais precisa que a detecção eletroquímica; e a alquilação do grupo tiol minimizou interferências de matriz. Por análise de HPLC-UV/Vis-ESI-MS/MS, a quantificação de trans-4-hidroxi-2-nonenal (HNE) e crotonaldeido conjugados com GSH demonstrou não haver alterações em cérebro e medula de ratos SOD1G93A. Contudo, há formação esteroespecífica dos adutos de HNE in vivo. Ressalta-se que a metodologia desenvolvida é extremamente sensível e específica e permite análise simultânea de GSH, GSSG, cisteína, cistina e dos adutos supracitados, servindo para análise de outros adutos de glutationilação de aldeídos que possam ser importantes em doenças associadas a estresse redox

Free radicais and oxidant species are associated with toxicological and pathophysiological processes. It has been demonstrated that production of reactive oxygen species may be involved in cell signaling and regulation. Several biomarkers of redox processes have been used, including adducts formed through the reaction of α,ß-unsaturated aldehydes with biomolecules such as DNA. In order to avoid these deleterious effects, aldehydes are detoxified through glutathionylation and further metabolized to mercapturic derivatives. However, assessing the redox status in biological systems is still a very complex task, and the difficulty in practical and accurate quantification of signaling effects and/or molecular damage is a major problem in redox studies. The objective of this work was to develop accurate and sensitive methods for analysis of potential biomarkers of redox stress, i.e., modified nucleosides, endogenous and exogenous aldehydes, glutathione and glutathionylation products, and their evaluation in cell, animal model and humans. Evaluation of urinary levels of 1,N2-propano-2'-deoxyguanosine (1,N2-propanodGuo), 1,N2-etheno-2'-deoxyguanosine and 8-oxo-7,8-dihydro-2'-deoxyguanosine in residents of São Paulo City - polluted region - showed a significant increase (p<0.05) in 1,N2-propanodGuo levels compared to residents of an unpolluted region by a HPLC-MS/MS methodology developed by the group. Moreover, it was proven, for the first time, that repair deficient cells have basal levels of 1,N2-propanodGuo higher than proficient cells in two independent strains, placing 1,N2-propanodGuo as a potential mediator of carcinogenesis in Fanconi Anemia patients. In an Amyotrophic Lateral Sclerosis (ALS) animal model (SOD1G93A rat) , a 50% increase in the levels of 1,N2-propanodGuo and 100% in the 1,N6-etheno-2'-deoxyadenosine in brain tissue in the symptomatic phase was observed, suggesting that the high brain lipid content may play a role, leading to impairment of cell metabolism and neuronal cell death. There is an increase of trans-hex-2-enal and trans,trans-hexa-2,4-dienal in asymptomatic SOD1G93A rats brain and of trans,trans-deca-2,4-dienal in symptomatic ones. However, no alteration was observed in spinal cord. Our approach contributes to a better understanding of the aldehyde status in vivo and allows us to predict biomolecule modifications. The developed methodology can contribute to lipidomic studies. The use of different techniques and sample preparation reflected in the reported levels of reduced (GSH) and oxidized glutathione (GSSG). The mass spectrometry technique proved to be more accurate than the electrochemical one, and the use of thiol alkylating agent minimizes matrix interference. No changes were observed in the levels of the GSH conjugates of trans-4-hydroxy-2-nonenal (HNE) and crotonaldehyde in brain and spinal cord of SOD1G93A rats quantified by HPLC-UV/Vis-ESI-MS/MS compared to controls. However, it was observed stereospecific HNE adducts formation in vivo. Note that this methodology is extremely sensitive and specific and allows simultaneous analysis of GSH, GSSG, Cys, cystine and the aforementioned adducts, serving for analysis of other aldehyde-glutathionylation adducts that may be important in pathologies associated with stress redox

Antioxidant factors, nitric oxide levels, and cellular damage in leprosy patients

Introduction The immune response caused by Mycobacterium leprae is a risk factor for the development of oxidative stress (OS) in leprosy patients. This study aimed to assess OS in leprosy patients before the use of a multidrug therapy. Methods We evaluated the nitric oxide (NO) concentration; antioxidant capacity; levels of malondialdehyde, methemoglobin and reduced glutathione; and the activity of catalase and superoxide dismutase (SOD) in leprosy patients. Results We observed lower SOD activity in these leprosy patients; however, the NO levels and antioxidant capacity were increased. Conclusions The infectious process in response to M. leprae could primarily be responsible for the OS observed in these patients. .

Effect of the tocotrienol-rich fraction on the lifespan and oxidative biomarkers in Caenorhabditis elegans under oxidative stress

OBJECTIVE: This study was performed to determine the effect of the tocotrienol-rich fraction on the lifespan and oxidative status of C. elegans under oxidative stress. METHOD: Lifespan was determined by counting the number of surviving nematodes daily under a dissecting microscope after treatment with hydrogen peroxide and the tocotrienol-rich fraction. The evaluated oxidative markers included lipofuscin, which was measured using a fluorescent microscope, and protein carbonyl and 8-hydroxy-2′-deoxyguanosine, which were measured using commercially available kits. RESULTS: Hydrogen peroxide-induced oxidative stress significantly decreased the mean lifespan of C. elegans, which was restored to that of the control by the tocotrienol-rich fraction when administered before or both before and after the hydrogen peroxide. The accumulation of the age marker lipofuscin, which increased with hydrogen peroxide exposure, was decreased with upon treatment with the tocotrienol-rich fraction (p<0.05). The level of 8-hydroxy-2′-deoxyguanosine significantly increased in the hydrogen peroxide-induced group relative to the control. Treatment with the tocotrienol-rich fraction before or after hydrogen peroxide induction also increased the level of 8-hydroxy-2′-deoxyguanosine relative to the control. However, neither hydrogen peroxide nor the tocotrienol-rich fraction treatment affected the protein carbonyl content of the nematodes. CONCLUSION: The tocotrienol-rich fraction restored the lifespan of oxidative stress-induced C. elegans and reduced the accumulation of lipofuscin but did not affect protein damage. In addition, DNA oxidation was increased. .

2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK3) and ascorbic acid (vitamin C, VC) is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H2O2) through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H2O2 production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H2O2 production. The compound 2-bromo-1,4-naphthoquinone (BrQ), in which the bromine atom substituted the methyl group in VK3, was approximately 10- and 19-fold more efficient than VK3 in terms of oxygen consumption and H2O2 production, respectively. The ratio [H2O2]produced / [naphthoquinone]consumed was 68 ± 11 and 5.8 ± 0.2 (µM/µM) for BrQ and VK3, respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK3 and BrQ reacted with glutathione (GSH), but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG). The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK3/VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK3 with BrQ will open new lines of investigation regarding this approach to cancer treatment.