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Reactive oxygen and nitrogen species (RONS) are involved in many biochemical processes, including nitro-oxidative stress that causes cancer cell death, observed in cancer therapies such as photodynamic therapy and cold atmospheric plasma. However, their mechanisms of action and selectivity still remain elusive due to the complexity of biological cells. For example, it is not well known how RONS generated by cancer therapies permeate the cell membrane to cause nitro-oxidative damage. There are many studies dedicated to the permeation of RONS across native and oxidized membranes, but not across nitrated membranes, another lipid product also generated during nitro-oxidative stress. Herein, we performed molecular dynamics (MD) simulations to calculate the free energy barrier of RONS permeation across nitrated membranes. Our results show that hydrophilic RONS, such as hydroperoxyl radical (HO2) and peroxynitrous acid (ONOOH), have relatively low barriers compared to hydrogen peroxide (H2O2) and hydroxyl radical (HO), and are more prone to permeate the membrane than for the native or peroxidized membranes, and similar to aldehyde-oxidized membranes. Hydrophobic RONS like molecular oxygen (O2), nitrogen dioxide (NO2) and nitric oxide (NO) even have insignificant barriers for permeation. Compared to native and peroxidized membranes, nitrated membranes are more permeable, suggesting that we must not only consider oxidized membranes during nitro-oxidative stress, but also nitrated membranes, and their role in cancer therapies.

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Propósito: Durante la sepsis y la ventilación mecánica, se genera estrés oxidativo por activación de las células pulmonares endoteliales e inflamatorias y producción de especies reactivas del oxígeno (ERO). Nuestro principal objetivo fue estudiar la producción pulmonar y sistémica de óxido nítrico (•NO) y oxidantes derivados del •NO que generan estrés nitroxidativo y su relación con la lesión pulmonar aguda (LPA) en pacientes en ventilación mecánica sépticos y no sépticos. Métodos: estudiamos 69 pacientes ventilados mecánicamente, de estos 36 pacientes con sepsis y 33 pacientes sin sepsis. Los pacientes fueron estudiados dentro de las primeras 48 horas de ingreso a unidad de cuidado intensivo (UCI). La producción de estrés nitroxidativo se comparó entre los pacientes con sepsis y los pacientes ventilados mecánicamente sin sepsis (VM). Ocho pacientes de quirófano sin enfermedad pulmonar sirvieron como grupo de control sano (GCBQ). Se analizaron nitrito más nitrato (NOx - ), 3-nitrotirosina (3-NT) y malondialdehído (MDA) en líquido de lavado bronquioloalveolar (LBA). En plasma se midió NOx - (n=69). Adicionalmente en plasma se midió 3-NT, MDA, y alfa tocoferol (α-TOH). Resultados: NO x - , 3-NT, MDA en LBA y NOx - y α-TOH en plasma fueron mayores en pacientes con sepsis que en los pacientes con VM sin sepsis (todos p <0,05). Tanto los pacientes con sepsis como VM tenían concentración de NOx - en LBA mayor que el grupo de control sano (p <0,001). En los pacientes con sepsis, los pacientes que fallecieron en la UCI tuvieron concentraciones mayores de NOx - en LBA que los sobrevivientes en la UCI, 80 (70 - 127) µM en comparación con 31 (15 - 47) µM, respectivamente, p <0,001. Los pacientes con síndrome de distress respiratorio agudo (SDRA) en el grupo sepsis tuvieron mayor concentración de NOx - en LBA. Conclusiones: Durante las fases tempranas de la sepsis y la ventilación Sepsis y Estrés Nitroxidativo Pulmonar 20 mecánica hay aumento del estrés nitroxidativo pulmonar y sistémico debido a un aumento de la producción de •NO que conduce a oxidantes secundarios derivados del •NO, los que promueven la nitración de proteínas y la peroxidación de lípidos. Esto se asocia con SDRA/LPA y aumento de la mortalidad en UCI

Purpose: During sepsis and mechanical ventilation oxidative stress is generated by endothelial and inflammatory lung cells. Our main objective was to study pulmonary and systemic •NO (nitric oxide) production and nitroxidative stress in mechanically ventilated septic patients. Methods: we study 69 mechanically ventilated patients, 36 with sepsis and 33 without sepsis within the first 48 hours of ICU admission compared with 33 mechanically ventilated patients without sepsis (MV) plus eight operating room patients without lung disease served as control healthy group (ORCG). Nitrite plus nitrate (NOx - ), 3-nitrotyrosine (3-NT) and malondialdehyde (MDA) in bronchoalveolar lavage fluid (BALF) were analyzed. Additionally, we measured plasma alpha tocopherol (α-TOH), MDA, and 3-NT. Results: BALF NOx - , BALF 3-NT, BALF MDA, and plasma NOx - were higher in the Sepsis than in MV patients (all p<0.05). Both SG and MV patients had higher BALF NOx - than the healthy control group (p<0.001). Sepsis patients had higher plasma NOx - and α TOH than mechanically-ventilated patients without sepsis (all p <0,05). In the Sepsis patients, the ICU non-survivors had higher levels of BALF NOx - than ICU survivors 280(70 - 127) µM versus 31(15 - 47) µM, p< 0.001. Conclusions: We conclude that during early phases of sepsis there is an enhanced lung nitroxidative stress due to an increase of •NO production leading to secondary Sepsis y Estrés Nitroxidativo Pulmonar 21 •NO-derived oxidants, which promote protein nitration and lipid peroxidation. This is associated with ARDS /ALI and increased mortality in ICU

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Infertility affects about 15% of couples of reproductive age. The male factor is involved in nearly 50% of infertility cases. Defective human sperm function has been associated with evidence of high levels of reactive oxygen species (ROS) and a resultant loss of fertilizing potential in vivo and in vitro. Analogous to what has been observed in somatic cells, mitochondria are likely the major sources of ROS in sperm cells. In this study, we analyzed mitochondrial function using high-resolution respirometry, ROS production, and footprints of oxidative and nitrative stress processes in intact human sperm cells. We showed that mitochondrial dysfunction (measured through the respiratory control ratio) was correlated with a decrease in human sperm motility. The samples analyzed presented nitro-oxidative modifications of proteins, such as protein 3-nitrotyrosine, that were observed mainly in the mid-piece (where mitochondria are localized) and in the sperm head. Semen samples presenting lower percentage of motile sperm showed higher amounts of nitro-oxidative protein modifications than those with larger quantities of motile sperm. When spermatozoa were exposed to inhibitors of the respiratory mitochondrial function, in the presence of a nitric oxide flux, sperm produced potent nitro-oxidative species (i.e., peroxynitrite). This effect was observed in more than 90% of intact living sperm cells and in sperm mitochondrial fractions. These data suggest that dysfunctional mitochondria in sperm cells produce oxidants that may contribute to male infertility. These data provide the rationale for testing the potential of compounds that improve sperm mitochondrial function to treat male infertility.

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