Exogenous niacin treatment increases NADPH oxidase in kiwifruit / O tratamento com niacina exógena NADPH oxidase em kiwis

Abstract Kiwifruit are a popular fruit worldwide; however, plant growth is threatened by abiotic stresses such as drought and high temperatures. Niacin treatment in plants has been shown to increase NADPH levels, thus enhancing abiotic stresses tolerance. Here, we evaluate the effect of niacin solution spray treatment on NADPH levels in the kiwifruit cultivars Hayward and Xuxiang. We found that spray treatment with niacin solution promoted NADPH and NADP+ levels and decreased both O2·- production and H2O2 contents in leaves during a short period. In fruit, NADPH contents increased during early development, but decreased later. However, no effect on NADP+ levels has been observed throughout fruit development. In summary, this report suggests that niacin may be used to increase NADPH oxidases, thus increasing stress-tolerance in kiwifruit during encounter of short-term stressful conditions.

Resumo Kiwis são uma fruta popular em todo o mundo; No entanto, o crescimento das plantas é ameaçado por estresses abióticos como a seca e as altas temperaturas. O tratamento com niacina em plantas mostrou aumentar os níveis de NADPH, aumentando assim a tolerância a stress abiótico. Aqui, avaliamos o efeito do tratamento com spray de solução de niacina sobre os níveis de NADPH nos cultivares de kiwis Hayward e Xuxiang. Descobrimos que o tratamento por spray com solução de niacina promoveu níveis de NADPH e NADP + e diminuiu a produção de O2·- e os teores de H2O2 nas folhas durante um curto período. Nos frutos, os teores de NADPH aumentaram durante o desenvolvimento precoce, mas diminuíram mais tarde. No entanto, não se observou qualquer efeito nos níveis de NADP + ao longo do desenvolvimento do fruto. Em resumo, este relatório sugere que a niacina pode ser utilizada para aumentar NADPH oxidases, aumentando assim a tolerância ao estresse em kiwis durante o encontro de condições estressantes de curto prazo.

Antioxidants in dermatology

Abstract The skin cells continuously produce, through cellular respiration, metabolic processes or under external aggressions, highly reactive molecules oxidation products, generally called free radicals. These molecules are immediately neutralized by enzymatic and non-enzymatic systems in a physiological and dynamic balance. In situations where this balance is broken, various cellular structures, such as the cell membrane, nuclear or mitochondrial DNA may suffer structural modifications, triggering or worsening skin diseases. several substances with alleged antioxidant effects has been offered for topical or oral use, but little is known about their safety, possible associations and especially their mechanism of action. The management of topical and oral antioxidants can help dermatologist to intervene in the oxidative processes safely and effectively, since they know the mechanisms, limitations and potential risks of using these molecules as well as the potential benefits of available associations.

Estrés oxidativo: ¿un estado celular defectuoso para la función espermática? / Oxidative stress: a defective cell state for sperm function?

En los organismos vivos, las cantidades de radicales libres y especies reactivas del oxígeno (ROS) son controladas por un complejo sistema de homeostasis, capaz de mantener niveles fisiológicos de ROS necesarios para el funcionamiento y regulación de algunas biomoléculas. Paralelamente, los organismos poseen sistemas bioquímicos de protección contra el estrés oxidativo, que consiste en el desbalance entre la producción de especies químicas altamente reactivas y las defensas antioxidantes de la célula. Dicho estrés contribuye de manera importante a la etiología tanto de la senescencia celular como de algunas enfermedades. En el contexto reproductivo, las células espermáticas pasan por una serie de cambios fisiológicos durante los procesos de maduración, capacitación y fecundados, entre los que se incluyen las modificaciones de las proteínas existentes, reguladas por señales procedentes del entorno espermático, donde las ROS modulan importantes vías bioquímicas, involucradas en procesos fundamentales de la función del espermatozoide y que se pueden alterar en estados de estrés oxidativo. El objetivo de esta revisión de literatura es describir algunos de los procesos que contribuyen al estrés oxidativo y sus implicaciones sobre la funcionalidad espermática.

Living organisms regulate the load of free radicals and reactive oxygen species (ROS) by a complex homeostatic system, capable of maintaining physiological levels of ROS, necessary for the action and regulation of some biomolecules. In parallel, organisms harbor biochemical protection systems against oxidative stress, consisting of an unbalance state between oxygen reactive chemical species and antioxidant defense production; this kind of biochemical stress has been shown to contribute to cellular senescence and the development of different diseases. In the reproductive field, the spermatic cells undergo a serial of physiological changes during the maturation, capacitation and fertilization process. Such changes include the modification of proteins regulated by signals from the sperm environment, where ROS modulate important biochemical pathways involved in fundamental processes of sperm function, and that could be altered under oxidative stress conditions. The objective of this review is to describe some of the processes that contribute to oxidative stress and its implications on sperm functionality.

El sistema antioxidante del glutatión en la etiopatología de la disfunción nigro-estriatal / Glutathione antioxidant system in the etiopathology of nigrostriatal dysfunction

La enfermedad de Parkinson es una enfermedad neurodegenerativa crónica que afecta a las personas de la tercera edad. En una minoría de los casos la enfermedad es de origen genético pero en el resto, la causa es idiopática. En este sentido, la acumulación de los radicales libres y la pérdida de la homeostasis del glutatión se han señalado como posibles agentes causales. El presente texto se propuso revisar las evidencias experimentales que apoyan la participación de los radicales libres y la pérdida de la homeostasis del glutatión en el comienzo y la progresión de la degeneración de la substantianigrapars compacta. El estrés oxidativo en la enfermedad de Parkinson´s puede estar relacionado con las propiedades pro-oxidantes intrínsecas de la dopamina y elevadas concentraciones de hierro en la substantianigrapars compacta, que promueven la oxidación de la dopamina y la generación de especies reactivas del oxígeno. Cualquier evento que desencadene estos mecanismos, genera un daño celular. La disminución del glutatión es una de las alteraciones bioquímicas más tempranas, detectadas en asociación con la enfermedad de Parkinson y se ha relacionado con la inhibición del complejo I de la cadena de transporte mitocondrial, daño oxidativo, activación glial, entre otros que favorecen la neurodegeneración. Estas evidencias sugieren la necesidad de mantener la homeostasis del glutatión en el sistema dopaminérgico y su vínculo con la etiología de la degeneración nigro-estriatal, lo que tiene una potencial aplicación en la práctica clínica.

Parkinson's disease is a chronic neurodegenerative condition affecting elderly persons. In a minority of cases the disease has a genetic origin, but in most the cause is idiopathic. Accumulation of free radicals and loss of glutathione homeostasis have been pointed at as possible causal agents. The purpose of the study was to review experimental evidence supporting the involvement of free radicals and loss of glutathione homeostasis in the outset and progress of substantia nigra pars compacta degeneration. Oxidative stress in Parkinson's disease may be related to the intrinsic pro-oxidant properties of dopamine and high iron concentrations in the substantia nigra pars compacta, promoting dopamine oxidation and the generation of reactive oxygen species. Any event triggering these mechanisms will cause cell damage. Glutathione reduction is one of the earliest biochemical alterations detected in association with Parkinson's disease, and it has been related to the inhibition of complex I of the mitochondrial transport chain, oxidative damage and glial activation, among other factors leading to neurodegeneration. This evidence points to the need to maintain glutathione homeostasis in the dopaminergic system, as well as its relationship to the etiology of nigrostriatal degeneration, of potential application in clinical practice.

Minimal endoscopic changes in non-erosive reflux disease / Alterações endoscópicas mínimas na doença do refluxo não erosiva

BACKGROUND: Gastroesophageal reflux disease is an increasingly common condition worldwide causing a considerable economic impact. More than half the patients with clinical symptoms of reflux disease display no mucosal erosions on esophagogastroduodenoscopy, making it impossible to confirm the diagnosis without further investigations. AIM: To evaluate the correlation between minimal endoscopic changes on white-light esophagogastroduodenoscopy (carditis, mucosal thickening and invisibility of vessels) and histologic changes observed in distal esophageal biopsies in a sample of patients with symptoms suggestive of reflux disease, and to verify the specificity of these symptoms for non-erosive reflux disease. METHODS: Retrospective, cross-sectional study based on information retrieved from a digital database at a Brazilian hospital for the period March-October, 2012. The sample consisted of previously untreated, non-smoking subjects aged >18 years with symptoms suggestive of reflux disease but no esophageal erosions, submitted to esophagogastroduodenoscopy and distal esophageal biopsy. RESULTS: The final sample included 23 subjects. The most frequently observed change was invisibility of vessels (n=21; 91.3%), followed by mucosal thickening (n=15; 65.2%) and carditis (n=5; 21.7%). The correlation coefficient between each variable and the anatomopathological diagnosis was 0.386 for body mass index, 0.479 for mucosal thickening, -0.116 for invisibility of vessels, 0.306 for carditis and 0.462 for hiatal hernia. CONCLUSION: All patients displayed minimal endoscopic changes on esophagogastroduodenoscopy, but only mucosal thickening revealed a moderately significant correlation with severity of esophagitis, although increased body mass index values and the presence of hiatal hernia were also associated. .

RACIONAL: Doença do refluxo gastroesofágico é condição cada vez mais comum em todo o mundo causando impacto econômico considerável. Mais da metade dos pacientes com sintomas clínicos da doença não apresentam erosões endoscópicas da mucosa, o que torna impossível confirmar o diagnóstico sem outras investigações. OBJETIVO: Avaliar a correlação entre mudanças mínimas endoscópicas em endoscopia digestiva alta de luz branca (cardite, espessamento da mucosa e invisibilidade de vasos) e as alterações histológicas observadas em biópsias distais de uma amostra de pacientes com sintomas sugestivos de doença do refluxo, e para verificar a especificidade desses sintomas para a doença não-erosiva. MÉTODOS: Estudo retrospectivo, transversal, com base em informações obtidas a partir de uma base de dados digital em um hospital brasileiro no período de março/outubro de 2012. A amostra foi composta por indivíduos não tratados previamente, não fumantes, >18 anos, com sintomas sugestivos de doença do refluxo, mas sem erosões esofágicas submetidos à endoscopia digestiva alta e biópsia de esôfago distal. RESULTADOS: A amostra final incluiu 23 indivíduos. A alteração mais frequente foi invisibilidade dos vasos (n=21; 91,3%), seguido por espessamento de mucosa (n=15; 65,2%) e cardite (n=5; 21,7%). O coeficiente de correlação entre cada variável e o diagnóstico anatomopatológico foi 0,386 para o índice de massa corporal, 0,479 para espessamento de mucosa, -0,116 para a invisibilidade de vasos, 0,306 para carditis e 0,462 para hérnia hiatal. CONCLUSÃO: Todos os pacientes apresentaram alterações endoscópicas mínimas, mas apenas espessamento da mucosa revelou correlação moderadamente significativa com a gravidade da esofagite, apesar do aumento dos valores no índice de massa corporal e da presença de hérnia hiatal também estarem associados. .

Caracterização do perfil de dano oxidativo em carcinoma mamário e avaliação de associação com parâmetroshistopatológicos / Profile characterization of oxidative damage in breast carcinoma and evaluation of association with histopathological parameters

O carcinoma mamário é uma doença complexa que engloba diversas alterações genéticas e bioquímicas, além de mudanças no microambiente tumoral, tais como o estresse oxidativo,que pode ocasionar danos estruturais em lipídios, proteínas, bem como no DNA nuclear. O presente estudo teve por objetivo caracterizar o perfil oxidativo de neoplasias mamárias,comparando o perfil de expressão de produtos dos processos de peroxidação lipídica, nitração proteica e oxidação de DNA em função de parâmetros histopatológicos com valor prognóstico quanto à evolução clínica do câncer de mama. (...) Contudo, quando o tamanho tumoral foi analisado separadamente entre tumores Triplo-Negativos ou entre os demais subtipos (Luminal A/B eHER2-like), não se observou efeito significativo sobre a expressão de 8-OHdG. Em conclusão, os dados indicam que alguns tumores Triplo-Negativos são mais resistentes a danos oxidativos sobre DNA, independentemente de grau ou tamanho tumoral, o que pode contribuir para o perfil de maior agressividade deste subtipo tumoral...

Breast cancer is a complex disease that involves multiple genetic and biochemical alterationsand changes in the tumor microenvironment, such as oxidative stress, which can lead tostructural damages to lipids, proteins and nuclear DNA. The present work aimed tocharacterize the oxidative profile of mammary tumors, comparing the products of profileexpression of lipid peroxidation processes, protein nitration and DNA oxidation according tohistopathological parameters with prognostic value as to clinical evolution of breast cancer. (...) However, when the tumor size was analyzed separately from Triple-Negativetumors or among the other subtypes (luminal A / B and HER2-like), there was no significanteffect on the expression of 8-OHdG. In conclusion, the data indicate that some triple-negativetumors are more resistant to oxidative damage over the DNA, regardless of tumor grade orsize, which may contribute to the more aggressive subtype of the tumor...

Análisis de riesgos de la brucelosis en el estado de Tlaxcala / Risk analysis of brucelosis in the state of Tlaxcala

Objetivo. Identificar los riesgos de la brucelosis en el estado de Tlaxcala, México. Material y métodos. Se realizó un diagnóstico de tipo social en los municipios de Huamantla, Ixtenco y Teacalco, localizadas en la región oriente del estado. Se determinó la seroprevalencia de brucelosis en cabras y humanos. Resultados. El 46.9% de productores conoce los programas de la vacunación contra brucelosis; 19.7% aplica vacuna y 80.3% no aplica vacuna. Huamantla presentó la mayor seroprevalencia de brucelosis animal en 66.8 por ciento. San José Teacalco distribuye y comercializa quesos no pasteurizados en una distancia mayor de 270 km, lo que amplía los riesgos de contagio por brucelosis. Ixtenco registró la mayor prevalencia de brucelosis en humanos con 1.51 por ciento. Conclusión. Los municipios estudiados presentan riesgos de contagio y propagación de la brucelosis.

Objective. To identify the risk of brucellosis in the state of Tlaxcala, Mexico. Materials and methods. A diagnosis of social type was conducted in the municipalities of Huamantla, Ixtenco and Teacalco, located in the eastern region of the state. The seroprevalence of brucellosis in goats and humans was determined. Results. 46.9% of producers know the programs of vaccination against brucellosis; 19.7% apply the vaccine and 80.3% do not apply the vaccine. Huamantla had the highest seroprevalence of animal brucellosis in 66.8%; San Jose Teacalco distributes unpasteurized cheeses to a distance of 270 km, increasing the risk of infection with brucellosis. Ixtenco recorded the highest prevalence of brucellosis in humans, with 1.51%. Conclusion. The municipalities studied present risks of infection and spread of brucellosis.

Oxidative stress and cellular immunity in patients with recurrent aphthous ulcers

Recurrent aphthous ulcer (RAU) is an inflammatory condition of the oral mucosa characterized by painful, well-circumscribed, single or multiple round or ovoid ulcerations. The exact etiologic factor(s) of these ulcerations are not yet understood. The objective of this study was to evaluate inflammatory processes and free radical metabolism of 25 patients with RAUs compared to 25 healthy controls. The levels of malondialdehyde (MDA) and glutathione (GSH) were determined by high-performance liquid chromatography. Tumor necrosis factor-alpha (TNF-α), interleukin-2 (IL-2), IL-10, and IL-12 were determined by ELISA. Nitric oxide (NO), myeloperoxidase (MPO), total antioxidant status (TAS), and total oxidant status (TOS) levels were measured spectroscopically in serum. The levels of MDA, GSH, TNF-α, IL-2, IL-12, MPO, and TOS, and oxidative stress index (OSI) were higher, and the levels of NO, IL-10, and TAS were lower in patients with RAU than in controls. Statistical analysis showed that GSH, TNF-α, IL-2, IL-10, and OSI differed significantly in patients with RAU compared to controls. These parameters have important roles in oxidant/antioxidant defense.

Free Radical Scavenging Activities of Nyctanthes arbor-tristis. L on Adjuvant Induced Arthritis in Rats.

Aims: The present study was undertaken to explore in vivo antioxidant potential of ethanol extracts of Nyctanthes arbor-tristis leaf and stem in adjuvant induced arthritic rats. Methodology: Arthritis induced rats were administered with extract of Nyctanthes arbortristis leaf and stem. (150 mg/kg body Weight/rat/day for 30 days. Results: A significant decrease in paw edema was observed following oral administration of the leaf and stem extracts. A significant (p<0.05) increase in the level of tissue TBARS, GPx and catalase was seen in arthritis induced rats (group II) and NAT treated rats (group III and group IV) showed a significant decrease in lipid peroxides, GPx and catalase level to near normalcy. The activity of total tissue SOD was found significantly (p<0.05) low in arthritis induced rats (group II) while a substantial increase in the activity to near normal level was noticed in NAT administered rats. The alterations in hematological and other biochemical parameters were restored to near normal levels after a treatment period of 30 days. The structural changes of the tissues shows the therapeutic ability of Nyctanthes arbor-tristis stem and leaf in experimental animals which were further evidenced by histological observations made on the hind limb tissue. Conclusion: As Nyctanthes arbor-tristis is of natural origin, it is a safe and effective intervention for free radical mediated diseases.

Oxidative stress evaluation of ischemia and reperfusion in kidneys under various degrees of hypothermia in rats

PURPOSE:To design an animal model of ischemia-reperfusion (I/R) in kidneys and evaluate the role that predetermined ranges of local hypothermia plays on markers of stress-oxydative as well as on histologic sections. METHODS: Twenty eight male rats Wistar, under general anesthesia, undergone right nephrectomy (G0, control group) followed by left kidney ischemia during 40 min. Four temperatures groups were designed, with seven animals randomized for each group: normothermic (G1, ±37ºC), mild hypothermia (G2, 26ºC), moderate hypothermia (G3, 15ºC) and deep hypothermia (G4, 4ºC). Left kidney temperature was assessed with an intraparenchymal probe. Left nephrectomy was performed after 240 min of reperfusion. After I/R a blood sample was obtained for f2-IP. Half of each kidney was sent to pathological evaluation and half to analyze CAT, SOD, TBARS, NO3, NO2. RESULTS:Histopathology showed that all kidneys under I/R were significantly more injured than the G0 (p<0.001). TBARS had increased levels in all I/R groups compared with the G0 (p<0.001). CAT had a significant difference (p<0.03) between G1 and G4. Finally, no difference was found on SOD, NO3, NO2 nor on f2-IP. CONCLUSION: This model of I/R was efficient to produce oxidative-stress in the kidney, showing that 4ºC offered significant decrease in free radicals production, although tissue protection was not observed.

Healing effects of Aegle marmelos (L.) Correa fruit extract on experimental colitis.

Graded doses of 50% ethanolic extract of dried fruit pulp of Aegle marmelos (AME) (100, 200 and 400 mg/kg) daily for 14 days in acetic acid (AA)-induced colitis in rats showed 200 mg/kg of AME as an optimal effective dose against AA-induced colonic damage score and weight. This dose (200 mg/kg; po) was further studied in AA-induced colitis for its effects on various physical (mucous/blood in stool, food and water intake and body weight changes), histology, antibacterial activity and biochemical parameters like free radicals (nitric oxide and lipid peroxidation), antioxidants (superoxide dismutase, catalase and reduced glutathione) and myeloperoxidase (acute-inflammatory marker) activities in rat colonic tissue. AME decreased colonic mucosal damage and inflammation (macroscopic and microscopic), mucous/bloody diarrhea, fecal frequency and increased body weight affected in AA-induced colitis. AME showed significant antibacterial activity and enhanced the antioxidants but decreased free radicals and myeloperoxidase activities thereby decreasing tissue damage and inflammation and thus, affording ulcer healing. The above effects of A. marmelos authenticated its use in indigenous system of Medicine.

Butein imparts free radical scavenging, anti-oxidative and pro-apoptotic properties in the flower extracts of Butea monosperma

The flower of Butea monosperma (Lam.) (Fabaceae) has been used in traditional Indian medicine in the treatment of many ailments including liver disorders. To understand the pharmacological basis of its beneficial effects, the extracts of dried flowers in water, methanol, butanol, ethyl acetate and acetone were evaluated for free radical scavenging and pro-apoptotic activities in cell cultures (human hepatoma Huh-7 cell line and immortalized AML-12 mouse hepatocytes). Butrin and butein -the active constituents of flower extracts- were used as reference molecules. The levels of cell injury markers like lactate dehydrogenase, glutathione and lipid peroxidation and primary antioxidant enzymes glutathione S-transferase and catalase were also measured. The aqueous and butanolic extracts exhibited better 2,2-diphenyl-1-picrylhydrazyl scavenging and cytotoxic activities in hepatoma cells than in immortalized hepatocytes. Interestingly, butein inhibited 2,2-diphenyl-1-picrylhydrazyl radical better than butrin. The aqueous and butanolic extracts were further investigated for hepatoprotection against carbon tertrachloride-induced biochemical changes and cell death. Both extracts, just as butrin and butein, significantly reversed the cellular glutathione levels and lipid peroxidation, and glutathione-S-transferase activity. Lactate dehydrogenase leakage and cell death were also prevented. However, only butein revived the catalase activity. Thus, the butein content of Butea monosperma flower extracts is important for free radical scavenging activity, apoptotic cell death and protection against oxidative injury in hepatic cells.

Voltammetric determination of antioxidant character in Berberis lycium Royel, Zanthoxylum armatum and Morus nigra Linn plants

The antioxidant activity potential of three different plant extracts was investigated against superoxide anion radical while employing cyclic voltammetry technique. The plants Berberis lyceum Royle, Morus nigra Linn and Zanthoxylum armatum were selected because of their potential use in the traditional medicine. The voltammetric response of the electrochemically generated superoxide anion radial in DMSO was monitored in the absence and presence of the plat extracts. The decrease in the current was interpreted in terms of antiradical activity of the added extract. The thermodynamic feasibility of the radical scavenging by extracts was accounted in terms of antioxidant activity coefficient [K[ao]] and standard Gibbs free energy [deltaG°]. The values of K[ao] and deltaG° ranged from 1.0 x 10[2] to 57 x 10[2] L[-1] and -18 to -27 kJmol[-1], respectively. The possible mechanism of the antioxidant reaction was regarded as E[r]C[i] mechanism i.e. reversible electron transfer followed by hydrogen atom transfer- an irreversible chemical reaction

Toxic effects of mercury, lead and gadolinium on vascular reactivity

Heavy metals have been used in a wide variety of human activities that have significantly increased both professional and environmental exposure. Unfortunately, disasters have highlighted the toxic effects of metals on different organs and systems. Over the last 50 years, the adverse effects of chronic lead, mercury and gadolinium exposure have been underscored. Mercury and lead induce hypertension in humans and animals, affecting endothelial function in addition to their other effects. Increased cardiovascular risk after exposure to metals has been reported, but the underlying mechanisms, mainly for short periods of time and at low concentrations, have not been well explored. The presence of other metals such as gadolinium has raised concerns about contrast-induced nephropathy and, interestingly, despite this negative action, gadolinium has not been defined as a toxic agent. The main actions of these metals, demonstrated in animal and human studies, are an increase of free radical production and oxidative stress and stimulation of angiotensin I-converting enzyme activity, among others. Increased vascular reactivity, highlighted in the present review, resulting from these actions might be an important mechanism underlying increased cardiovascular risk. Finally, the results described in this review suggest that mercury, lead and gadolinium, even at low doses or concentrations, affect vascular reactivity. Acting via the endothelium, by continuous exposure followed by their absorption, they can increase the production of free radicals and of angiotensin II, representing a hazard for cardiovascular function. In addition, the actual reference values, considered to pose no risk, need to be reduced.

Iron mediates endothelial cell damage and blood-brain barrier opening in the hippocampus after transient forebrain ischemia in rats

Blood cells are transported into the brain and are thought to participate in neurodegenerative processes following hypoxic ischemic injury. We examined the possibility that transient forebrain ischemia (TFI) causes the blood-brain barrier (BBB) to become permeable to blood cells, possibly via dysfunction and degeneration of endothelial cells in rats. Extravasation of Evans blue and immunoglobulin G (IgG) was observed in the hippocampal CA1-2 areas within 8 h after TFI, and peaked at 48 h. This extravasation was accompanied by loss of tight junction proteins, occludin, and zonula occludens-1, and degeneration of endothelial cells in the CA1-2 areas. Iron overload and mitochondrial free radical production were evident in the microvessel endothelium of the hippocampus before endothelial cell damage occurred. Administration of deferoxamine (DFO), an iron chelator, or Neu2000, an antioxidant, blocked free radical production and endothelial cell degeneration. Our findings suggest that iron overload and iron-mediated free radical production cause loss of tight junction proteins and degeneration of endothelial cells, opening of the BBB after TFI.

Assessment of free radical-mediated damage in head and neck squamous cell carcinoma patients and after treatment with radiotherapy.

Reactive oxygen species (ROS) produced as a part of cellular metabolism can interact with biological macromolecules such as DNA, proteins and lipids and interfere with their normal functions, leading to the loss of cellular viability. ROS have been implicated in many pathophysiological conditions including cancer. In the present study, the damage caused by ROS and the effect of radiation in head and neck squamous cell carcinoma (HNSCC) patients were assessed in the erythrocytes by analyzing the superoxide dismutase (SOD) and catalase (CAT) activities, and levels of total thiols (T-SH) and malondialdehyde (MDA, a marker for lipid peroxidation). Blood samples were collected before the start of treatment and after the completion of radiotherapy. Both SOD and CAT activities were decreased in untreated patients, but elevated in patients after treatment. The T-SH levels were also depleted in untreated HNSCC patients, but elevated non-significantly after radiation therapy (p>0.05). The levels of MDA showed a significant increase in both untreated patients and after radiation therapy when compared with normal subjects (p<0.05). Thus, the present study indicated that the free radical-mediated damage was aggravated in untreated HNSCC patients, but the levels of antioxidants returned to baseline or nearly so after the treatment with radiation therapy.

Advancement of methanol poisoning mechanism research / 法医学杂志

The methanol poisoning by oral intake or skin contact occurs occasionally, which may have serious consequences including blindness and/or death. Methanol and its metabolites, formaldehyde and formic acid, are associated with metabolic acidosis, visual dysfunction and neurological symptoms. At present, the mechanism of methanol poisoning primarily focuses on the cell hypoxia, the alteration of structure and biological activity induced by free radical and lactic acid. Meanwhile, methanol poisoning causes changes in the balance between the production of free radicals and antioxidant capacity and in the proteases-protease inhibitors system, which lead to a series of disturbances.

Toxicidade de aminoacetona e células produtoras de insulina / Cytotoxity of aminoacetone on insulin-producing cells

Danos induzidos por hiperglicemia em tecidos no diabetes são caracterizados por quatro mecanismos conectados: aumento do fluxo metabólico através da via do poliol, ativação da proteína quinase C (PKC), aumento da atividade da via das hexosaminas e aumento da produção intracelular dos precursores dos produtos finais de glicação avançada (AGEs). Entre eles, os derivados de metilglioxal, um potente agente de modificação de proteínas e DNA, têm sido associados a complicações microvasculares no diabetes: nefropatia, retinopatia e neuropatia. O metilglioxal é produzido a partir das trioses fosfato, acetona e aminoacetona, um catabólito de treonina e glicina, gerado na matriz mitocondrial. A aminoacetona sofre oxidação enzimática, catalisada por aminoxidase sensível a semicarbazida (SSAO), ou química, catalisada por íons de cobre e ferro, produzindo metilglioxal, H2O2 e NH4 +. Sabendo que metilglioxal e H2O2 são capazes de induzir apoptose e/ou necrose em células produtoras de insulina (RINm5f) propomos uma possível atividade pró-oxidante da aminoacetona sobre células beta do pâncreas. O tratamento destas linhagens com aminoacetona/Cu(II) aumentou a morte celular, fluxo de Ca2+ intracelular, produção de NO, fragmentação do DNA, depleção dos níveis de glutationa reduzida (GSH), expressão gênica da proteína apoptótica Bax, enzimas antioxidantes - glutationa peroxidase (GPx), glutationa redutase (GRd), catalase e isoformas de superóxido dismutases (CuZnSOD e MnSOD) - e óxido nítrico sintase induzida (iNOS). Embora as concentrações normais e patológicas da aminoacetona, provavelmente seja muito menores que as usadas nos experimentos, sugerimos que, em tecidos de diabéticos, um acúmulo da aminoacetona em longo prazo pode conduzir a danos oxidativos e eventualmente morte das células beta do pâncreas.

Tissue damages induced by hyperglycemia in diabetics are characterized by four linked mechanisms: increased flux through the polyol pathway, protein kinase C (PKC) activation, increased hexosamine pathway activity and intracellular production of advanced glycation end product (AGE) precursors. The production of AGEs by modifying proteins and DNA agent, such as methylglyoxal, has been implicated in microvascular complications in diabetes: nephropathy, retinopathy and neuropathy. Methylglyoxal is putatively produced in vivo from trioses phosphate, acetone and aminoacetone, a catabolite of threonine and glycine synthesized in the mitochondrial matrix. Aminoacetone has been reported to undergo semicarbazide sensitive amine oxidase- catalyzed and copper- and iron-catalyzed oxidations by molecular oxygen to methylglyoxal, NH4 + ion and H2O2. Considering that methylglyoxal and H2O2 have been found to promote apoptosis/necrosis to insulin-producing cells (RINm5f), we propose a possible pro-oxidant role of aminoacetone in pancreatic beta-cells. Treatment of RINm5f cells with aminoacetone plus Cu(II) ion promotes an increase of non-viable cells, influx of Ca2+ ions, NO production, DNA fragmentation, depletion of reduced glutathione (GSH) levels, and increased mRNA expression of pro-apoptotic protein (Bax), antioxidant enzymes - glutathione peroxidase (GPx), glutathione reductase (GRd), MnSOD, CuZnSOD and catalase - and inducible nitric oxide synthase (iNOS). Although both normal and pathological concentrations of aminoacetone are probably much lower than those used here, it is tempting to propose that excess aminoacetone in diabetic patients, at long term, may drive oxidative damage and eventually death of pancreatic beta-cells.

Oxidative Stress in Cardiovascular Disease.

Over the last two decades, it has become increasingly clear that reactive oxygen species (ROS), including free radicals are involved in cardiovascular disease. In recent years, there has been a growing interest in the clinical implications of these oxidants. The ROS are common by-products of many oxidative biochemical and physiological processes. They can be released by xanthine oxidase, NAD(P)H oxidase, lipoxygenases, mitochondria, or the uncoupling of nitric oxide synthase in vascular cells. ROS mediate various signaling pathways that underlie vascular inflammation in atherogenesis. Various animal models of oxidative stress support that ROS have causal role in atherosclerosis and other cardiovascular diseases. They are too reactive to be tolerated in living tissue, and aerobic organisms use sophisticated defense system, both enzymatic and non-enzymatic for prevention of overload of free radicals. In a number of pathophysiological conditions, the delicate equilibrium between free-radical production and antioxidant capability can be altered in favor of the former, thus leading to oxidative stress and increased tissue injury. This review focuses on the biochemical evidences concerning involvement of ROS in several cardiovascular diseases, namely atherosclerosis, heart failure, hypertension and ischemia/reperfusion injury.