Specificity of H2O2 signaling in leaf senescence: is the ratio of H2O2 contents in different cellular compartments sensed in Arabidopsis plants?

Leaf senescence is an integral part of plant development and is driven by endogenous cues such as leaf or plant age. Developmental senescence aims to maximize the usage of carbon, nitrogen and mineral resources for growth and/or for the sake of the next generation. This requires efficient reallocation of the resources out of the senescing tissue into developing parts of the plant such as new leaves, fruits and seeds. However, premature senescence can be induced by severe and long-lasting biotic or abiotic stress conditions. It serves as an exit strategy to guarantee offspring in an unfavorable environment but is often combined with a trade-off in seed number and quality. In order to coordinate the very complex process of developmental senescence with environmental signals, highly organized networks and regulatory cues have to be in place. Reactive oxygen species, especially hydrogen peroxide (H2O2), are involved in senescence as well as in stress signaling. Here, we want to summarize the role of H2O2 as a signaling molecule in leaf senescence and shed more light on how specificity in signaling might be achieved. Altered hydrogen peroxide contents in specific compartments revealed a differential impact of H2O2 produced in different compartments. Arabidopsis lines with lower H2O2 levels in chloroplasts and cytoplasm point to the possibility that not the actual contents but the ratio between the two different compartments is sensed by the plant cells.

The human microglial HMC3 cell line: where do we stand? A systematic literature review.

Microglia, unique myeloid cells residing in the brain parenchyma, represent the first line of immune defense within the central nervous system. In addition to their immune functions, microglial cells play an important role in other cerebral processes, including the regulation of synaptic architecture and neurogenesis. Chronic microglial activation is regarded as detrimental, and it is considered a pathogenic mechanism common to several neurological disorders. Microglial activation and function have been extensively studied in rodent experimental models, whereas the characterization of human cells has been limited due to the restricted availability of primary sources of human microglia. To overcome this problem, human immortalized microglial cell lines have been developed. The human microglial clone 3 cell line, HMC3, was established in 1995, through SV40-dependent immortalization of human embryonic microglial cells. It has been recently authenticated by the American Type Culture Collection (ATCC®) and distributed under the name of HMC3 (ATCC®CRL-3304). The HMC3 cells have been used in six research studies, two of which also indicated by ATCC® as reference articles. However, a more accurate literature revision suggests that clone 3 was initially distributed under the name of CHME3. In this regard, several studies have been published, thus contributing to a more extensive characterization of this cell line. Remarkably, the same cell line has been used in different laboratories with other denominations, i.e., CHME-5 cells and C13-NJ cells. In view of the fact that "being now authenticated by ATCC®" may imply a wider distribution of the cells, we aimed at reviewing data obtained with the human microglia cell line clone 3, making the readers aware of this complicated nomenclature. In addition, we also included original data, generated in our laboratory with the HMC3 (ATCC®CRL-3304) cells, providing information on the current state of the culture together with supplementary details on the culturing procedures to obtain and maintain viable cells.

Mechanisms of cardiac radiation injury and potential preventive approaches.

In addition to cytostatic treatment and surgery, the most common cancer treatment is gamma radiation. Despite sophisticated radiological techniques however, in addition to irradiation of the tumor, irradiation of the surrounding healthy tissue also takes place, which results in various side-effects, depending on the absorbed dose of radiation. Radiation either damages the cell DNA directly, or indirectly via the formation of oxygen radicals that in addition to the DNA damage, react with all cell organelles and interfere with their molecular mechanisms. The main features of radiation injury besides DNA damage is inflammation and increased expression of pro-inflammatory genes and cytokines. Endothelial damage and dysfunction of capillaries and small blood vessels plays a particularly important role in radiation injury. This review is focused on summarizing the currently available data concerning the mechanisms of radiation injury, as well as the effectiveness of various antioxidants, anti-inflammatory cytokines, and cytoprotective substances that may be utilized in preventing, mitigating, or treating the toxic effects of ionizing radiation on the heart.

Systemic Oxidative Stress in Women with Ovarian and Pelvic Endometriosis: Role of Hormonal Therapy.

This study was performed to evaluate the systemic oxidative stress balance in women with either ovarian or deep infiltrating endometriosis (DIE) and any alterations of the same during hormone therapy. Free oxygen radicals (FORT) and free oxidant radical defense (FORD) were measured in the capillary blood of 24 women without endometriosis, 26 women with endometrioma, and 26 women with DIE with or without endometrioma. Endometriosis was diagnosed by clinical and ultrasound assessment. Dietary factors, lifestyle habits, and intake of any substances interfering with the oxidative status were recorded. Women were prescribed contraceptive hormones, and the baseline assessments were repeated at the 3rd month of use, revealing a higher oxidative stress balance (FORT/FORD) in women with endometriosis than in controls (4.75 ± 4.4 vs. 2.79 ± 2.2; p = 0.05). The highest values were found in women with DIE (5.34 ± 4.6; p = 0.028 vs. controls). Regression analysis revealed an independent link between FORT/FORD and endometrioma (b 2.874, 95% CI 0.345, 5.403; p = 0.027) and DIE (b 4.419, 95% CI 1.775, 7.064; p = 0.001) but a negative correlation with HDL-cholesterol (b -0.063, 95% CI -0.125, -0.002; p = 0.043). In controls, the hormone therapy increased FORT (p = 0.003), but also FORD (p = 0.012), with the FORT/FORD balance remaining stable (2.72 ± 2.2 vs. 2.73 ± 1.8; p = 0.810). In women with endometriosis, FORT remained unchanged, but FORD increased (p = 0.004), and the FORT/FORD ratio significantly decreased (4.75 ± 4.4 vs. 2.57 ± 1.76; p = 0.002) to values similar to the control levels. These data indicate that systemic oxidative stress balance increased in women with endometriosis, particularly in those with DIE. The hormonal therapy did not change the oxidative stress balance in control women but significantly improved it in women with endometriosis, particularly those suffering from DIE.

Analysis of Short-Term and Stable DNA Damage in Patients with Differentiated Thyroid Cancer Treated with 131I in Hypothyroidism or with Recombinant Human Thyroid-Stimulating Hormone for Remnant Ablation.

It is well known that ionizing radiation can induce genetic damage and that oxidative stress is a major factor inducing it. Our aim was to investigate whether thyroid remnant ablation with low activities of 131I (1,850 MBq) is associated with DNA damage by evaluating the CometAssay, micronuclei, and chromosome aberrations with multicolor fluorescent in situ hybridization. Methods: We studied 62 patients prepared with recombinant human thyroid-stimulating hormone (rhTSH) or by thyroid hormone withdrawal. In both groups, we analyzed stable and unstable genetic alterations before 131I therapy and 1 wk and 3 mo after 131I administration. We also correlated the genetic damage with several variables, including the degree of radiation-induced oxidative stress, genetic polymorphisms of enzymes involved in DNA repair, and antioxidative stress. Results: We found a comparable amount of DNA breaks evaluated by CometAssay and micronuclei testing in both groups of patients at different time points, but there was a significant increase in stable chromosome aberrations evaluated by multicolor fluorescent in situ hybridization (breaks and translocations) in patients prepared with thyroid hormone withdrawal. Overall, high chromosome damage was associated with higher retained body radioactivity and unfavorable gene polymorphism. A high level of free oxygen radicals and a low level of antioxidants were found in all patients at any time point. In particular, patients prepared with thyroid hormone withdrawal, at 3 mo, had significantly higher levels of free oxygen radicals than those prepared with rhTSH. Conclusion: An increase in stable chromosome aberrations with respect to baseline is detectable after administration of low doses of 131I in patients prepared with thyroid hormone withdrawal but not in patients prepared with rhTSH. The clinical significance of these chromosomal alterations remains to be determined.

The Role of Free Oxygen Radicals in Lasting Hyperexcitability of Rat Subicular Neurons After Exposure to General Anesthesia During Brain Development.

A large number of preclinical studies have established that general anesthetics (GAs) may cause neurodevelopmental toxicity in rodents and nonhuman primates, which is followed by long-term cognitive deficits. The subiculum, the main output structure of hippocampal formation, is one of the brain regions most sensitive to exposure to GAs at the peak of synaptogenesis (i.e., postnatal day (PND) 7). We have previously shown that subicular neurons exposed to GAs produce excessive amounts of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), which is a known modulator of neuronal excitability. To further explore the association between GA-mediated increase in ROS levels and long-term functional changes within subicular neurons, we sought to investigate the effects of ROS on excitability of these neurons using patch-clamp electrophysiology in acute rat brain slices. We hypothesized that both acute application of H2O2 and an early exposure (at PND 7) to GA consisting of midazolam (9 mg/kg), 70% nitrous oxide, and 0.75% isoflurane can affect excitability of subicular neurons and that superoxide dismutase and catalase mimetic, EUK-134, may reverse GA-mediated hyperexcitability in the subiculum. Our results using whole-cell recordings demonstrate that acute application of H2O2 has bidirectional effects on neuronal excitability: lower concentrations (0.001%, 0.3 mM) cause an excitatory effect, whereas higher concentrations (0.01%, 3 mM) inhibited neuronal firing. Furthermore, 0.3 mM H2O2 increased the average action potential frequency of subicular neurons by almost twofold, as assessed using cell-attach configuration. Finally, we found that preemptive in vivo administration of EUK-134 reduced GA-induced long-lasting hyperexcitability of subicular neurons ex vivo when studied in neonatal and juvenile rats. This finding suggests that the increase in ROS after GA exposure may play an important role in regulating neuronal excitability, thus making it an attractive therapeutic target for GA-induced neurotoxicity in neonates.

The immunohistochemical and histologic effects of contrast medium on uterus, fallopian tubes and ovaries, given during hysterosalpingography: rat study

Objective: Previous studies have shown that damage occurs to internal genital tract during hysterosalpingography (HSG). The aim was to show that endometrial and tubal epithelium underwent free radical damage during HSG in an animal model. Material and Methods: Forty rats were evaluated in five different groups. Two groups received ionizing radiation (15-20 miliRad three times) only. Two further groups received ionizing radiation in combination with iohexol (1-2 mL). The remaining group served as control. Groups were evaluated after seven and forty-two days. Inflammation and cellular changes were evaluated histopathologically. Cellular activity of antioxidant enzymes was assessed immunohistochemically. Results: Inflammation, and cellular changes were detected at certain rates in all groups (p<0.001). Glutathione reductase, catalase, superoxide dismutase, glutathione S-transferase activities were found to be increased after the HSG (p<0.001). Conclusion: It is obvious that the cell suffers acute and chronic damage during HSG due to both radioactivity and chemicals. Although there is a lot of research done before, there is no definitive method yet to protect against the harmful effects of iodinated contrast agents and ionizing radiation. So, new methods need to be explored to protect cells and tissues from reactive oxygen radical damage caused by HSG.

The effect of intrauterine resuscitation by maternal hyperoxygenation on perinatal and maternal outcome: a randomized controlled trial.

BACKGROUND: Maternal hyperoxygenation is widely used during labor as an intrauterine resuscitation technique. However, robust evidence regarding its beneficial effect and potential side effects is scarce, and previous studies show conflicting results. OBJECTIVE: To assess the effect of maternal hyperoxygenation upon suspected fetal distress during the second stage of term labor on fetal heart rate, neonatal outcome, maternal side effects, and mode of delivery. MATERIALS AND METHODS: In a single-center randomized controlled trial in a tertiary hospital in The Netherlands, participants were randomized in case of an intermediary or abnormal fetal heart rate pattern during the second stage of term labor, to receive either conventional care or 100% oxygen at 10 L/min until delivery. The primary outcome was the change in fetal heart rate pattern. Prespecified secondary outcomes were Apgar score, umbilical cord blood gas analysis, neonatal intensive care unit admission, perinatal death, free oxygen radical activity, maternal side effects, and mode of delivery. We performed subgroup analyses for intermediary and abnormal fetal heart rate, and for small for gestational age fetuses. RESULTS: From March 2016 through April 2018, a total of 117 women were included. Fetal heart rate patterns could be analyzed in 71 women. Changes in fetal heart rate (defined as improvement, equal, or deterioration) in favor of maternal hyperoxygenation were significant (odds ratio, 5.7; 95% confidence interval, 1.7-19.1) using ordinal logistic regression. Apgar score, umbilical cord blood gas analysis, free oxygen radicals, and mode of delivery showed no significant differences between the intervention and control group. Among women with an abnormal fetal heart rate, there were fewer episiotomies on fetal indication in the intervention group (25%) than in the control group (65%, P < .01). CONCLUSION: Maternal hyperoxygenation has a positive effect on the fetal heart rate in the presence of suspected fetal distress during the second stage of labor. There was no significant difference in the mode of delivery or neonatal outcome; however, significantly fewer episiotomies on fetal indication were performed following maternal hyperoxygenation in the subgroup with abnormal fetal heart rate pattern.

Intrauterine resuscitation during the second stage of term labour by maternal hyperoxygenation versus conventional care: study protocol for a randomised controlled trial (INTEREST O2).

BACKGROUND: Perinatal asphyxia is, even in developed countries, one the major causes of neonatal morbidity and mortality. Therefore, if foetal distress during labour is suspected, one should try to restore foetal oxygen levels or aim for immediate delivery. However, studies on the effect of intrauterine resuscitation during labour are scarce. We designed a randomised controlled trial to investigate the effect of maternal hyperoxygenation on the foetal condition. In this study, maternal hyperoxygenation is induced for the treatment of foetal distress during the second stage of term labour. METHODS/DESIGN: This study is a single-centre randomised controlled trial being performed in a tertiary hospital in The Netherlands. From among cases of a suboptimal or abnormal foetal heart rate pattern during the second stage of term labour, a total of 116 patients will be randomised to the control group, where normal care is provided, or to the intervention group, where before normal care 100% oxygen is supplied to the mother by a non-rebreathing mask until delivery. The primary outcome is change in foetal heart rate pattern. Secondary outcomes are Apgar score, mode of delivery, admission to the neonatal intensive care unit and maternal side effects. In addition, blood gas values and malondialdehyde are determined in umbilical cord blood. DISCUSSION: This study will be the first randomised controlled trial to investigate the effect of maternal hyperoxygenation for foetal distress during labour. This intervention should be recommended only as a treatment for intrapartum foetal distress, when improvement of the foetal condition is likely and outweighs maternal and neonatal side effects. TRIAL REGISTRATION: EudraCT, 2015-001654-15; registered on 3 April 2015. Dutch Trial Register, NTR5461; registered on 20 October 2015.

Acrolein Can Cause Cardiovascular Disease: A Review.

Acrolein is a highly reactive unsaturated aldehyde that is formed during the burning of gasoline and diesel fuels, cigarettes, woods and plastics. In addition, acrolein is generated during the cooking or frying of food with fats or oils. Acrolein is also used in the synthesis of many organic chemicals and as a biocide in agricultural and industrial water supply systems. The total emissions of acrolein in the United States from all sources are estimated to be 62,660 tons/year. Acrolein is classified by the Environmental Protection Agency as a high-priority air and water toxicant. Acrolein can exert toxic effects following inhalation, ingestion, and dermal exposures that are dose dependent. Cardiovascular tissues are particularly sensitive to the toxic effects of acrolein based primarily on in vitro and in vivo studies. Acrolein can generate free oxygen radical stress in the heart, decrease endothelial nitric oxide synthase phosphorylation and nitric oxide formation, form cytoplasmic and nuclear protein adducts with myocyte and vascular endothelial cell proteins and cause vasospasm. In this manner, chronic exposure to acrolein can cause myocyte dysfunction, myocyte necrosis and apoptosis and ultimately lead to cardiomyopathy and cardiac failure. Epidemiological studies of acrolein exposure and toxicity should be developed and treatment strategies devised that prevent or significantly limit acrolein cardiovascular toxicity.

Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress.

The effect of various abiotic stresses on photosynthetic apparatus is inevitably associated with formation of harmful reactive oxygen species (ROS). In this review, recent progress on ROS production by photosystem II (PSII) as a response to high light and high temperature is overviewed. Under high light, ROS production is unavoidably associated with energy transfer and electron transport in PSII. Singlet oxygen is produced by the energy transfer form triplet chlorophyll to molecular oxygen formed by the intersystem crossing from singlet chlorophyll in the PSII antennae complex or the recombination of the charge separated radical pair in the PSII reaction center. Apart to triplet chlorophyll, triplet carbonyl formed by lipid peroxidation transfers energy to molecular oxygen forming singlet oxygen. On the PSII electron acceptor side, electron leakage to molecular oxygen forms superoxide anion radical which dismutes to hydrogen peroxide which is reduced by the non-heme iron to hydroxyl radical. On the PSII electron donor side, incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. Under high temperature, dark production of singlet oxygen results from lipid peroxidation initiated by lipoxygenase, whereas incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. The understanding of molecular basis for ROS production by PSII provides new insight into how plants survive under adverse environmental conditions.

[Inflammation and oxidation: predictive and/or causative factors]. / Inflamación y oxidación: factores predictivos y/o causales.

Brain ageing leads to a series of changes that reduce the processes of adaptation and response. These transformations can end in cognitive impairment and/or dementia. Although the cause of these changes is diverse, inflammation and oxidative stress explain some of the pathophysiological mechanisms of these anomalies of brain functioning. Neuroinflammation triggers neuronal injury through the presence of inflammatory cytokines and the activation of microglia through membrane receptors and nuclear activation factors. This neuroinflammatory phenomenon also affects neuron plasticity, altering the genesis and maintenance of long-term potentiation, leading to impairment of hippocampus-dependent memory. Oxidative stress and the production of free oxygen radicals also cause toxic effects in aged brains, largely due to lipid peroxidation and DNA damage. The identification of the molecular mechanisms involved in the pathogenesis of these events could shed new light on possible therapeutic targets and offer strategies for the prevention of diseases related to brain ageing, cognitive impairment and dementia.

Tissue content of metalloproteinase-9 and collagen in the colon with and without fecal stream after intervention with infliximab in rats subjected to Hartmann's surgery

ABSTRACT Purpose Quantify the tissue content of metalloproteinase-9 (MMP-9) and collagen in colic mucosa with and without intestinal transit after infliximab administration in rats subjected to Hartmann's surgery. Methods Twenty-two rats underwent colon diversion by Hartmann's surgery. Animals were maintained with intestinal bypass for 12 weeks to induce development of diversion colitis (DC). Afterwards, animals were divided into three groups: first group received subcutaneous application of saline solution (SS) 0.9%, while the remaining two groups received infliximab subcutaneously at doses of 5 or 10 mg·kg-1·week-1 for five consecutive weeks. After the intervention, animals were sacrificed, removing the segments with and without intestinal transit. Diversion colitis was diagnosed by histological study, and its intensity was determined by a validated inflammatory scale. Tissue expression of MMP-9 was assessed byimmunohistochemistry, while total collagen was assessed by histochemistry. Tissue content of both was measuredby computerized morphometry. Results Colon segments without intestinal transit had a higher degree of inflammation, which improved in animals treated with infliximab. Collagen content was always lower in those without intestinal transit. There was an increase in the collagen content in the colon without transit in animals treated with infliximab, primarily at a dose of 10 mg·kg-1·week-1. There was an increase in the content of MMP-9 in the colon without fecal transit, and a reduction was observed in animals treated with infliximab, regardless of the dose used. Conclusions Application of infliximab reduces inflammation, increases the total collagen content and decreases the content of MMP-9 in the colon without intestinal transit.

Myeloperoxydase expression in the pathogenesis of nasal polyps.

Nasal polyps are benign mucosal protrusions that expand into the nasal cavity. There are no any etiological factors that may explain the pathogenesis of nasal polyps but currently inflammation continues to be the major factor. As a result of inflammation, neutrophils become activated and migrate to the inflammatory area and form their bactericidal effects by producing free oxygen radicals. The objective of our study is to investigate the expression of myeloperoxydase enzyme, which is usually an indicator of leukocyte infiltration and is responsible in the formation of free oxygen radicals in polyp tissues and to determine its role in the pathogenesis of nasal polyps.

The Protective Effect of Free Oxygen Radical Inhibitors on Na-salicylate Induced Cochlear Damage in Guinea Pig / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: To elucidate the mechanism of salicylate ototoxicity of free oxygen radicals (FORs), we made an animal model with Na-salicylate cochlear toxicity and evaluated the protective effect of free oxygen radical inhibitors. MATERIALS AND METHODS: Na-salicylate soaked in gelfoam was placed on the round window niche of guinea pigs for 2 hours. After removal of gelfoam, electrocochleography and evoked otoacoustic emission test were performed at regular time intervals. These tests were repeated to see the protective effect of FORs inhibitors after the injection of allopurinol or superoxide dismutase (SOD). RESULTS: Hearing loss was noted after removal of gelfoam which was soaked with Na-salicylate. After 6 hours, these ototoxicity effects disappeared. The OAE test showed similar response. FORs inhibitors showed protective effects and SOD was more effective than allopurinol. CONCLUSION: These results support the idea that FORs activity contributes to ototoxicity of Na-salicylate. This damage can be diminished by treatment with drugs that scavenge and inhibit the formation of FORs.

An Effect of Allopurinol on Salicylate Ototoxicity in Guinea Pigs / 대한이비인후과학회지

The mechanism of salicylate ototoxicity appears to be multifactorial and decreased cochlear blood flow seems to play an important role. The purpose of the study was to assess an effect of allpurinol, a blocker of free oxygen radicals(FORs) formation, on salicylate ototxicity in guinea pig. ABR threshold shifts were observed in group 1, treated with salicylate(300mg/kg, IM) and group 2, pretreated with allopurinol(50mg/kg, PO, two times) before injection of salicylate(300mg/kg, IM). In group 1, significant ABR threshold shift was measured in 1 hour(p<0.05) and maximum threshold shift was noted in 2-3 hours, with complete recovery in 6 hours, after injection of salicylate. In group 2, there was a little ABR threshold shift through 6 hours after injection of salicylate, except average 5dB shift in 4 hours. ABR threshold shift was significantly greater in group 1 than in group 2, after injection of salicylate(p<0.05). With above result, allopurinol, a blocker of FORs formation, could attenuated the hearing loss after the administration of salicylate in guinea pig, and FORs might play a role in salicylateinduced hearing loss.

Effects of benazepril on cardiac function, free oxygen radicals, sarcoplasmic reticulum Ca~(2+)- ATPase following cardiac ischemia- reperfusion in spontaneously hypertensive rats / 中国病理生理杂志

AIM: To investigate the effects of angiotensin converting enzyme inhibitor (ACEI), benazepril(B), on cardiac function, free oxygen radicals, sarcoplasmic reticulum(SR) Ca~(2+)-ATPase following ischemia-reper-fusion in sportaneously hypertensive rats (SHRs). METHODS: Thirty 10-week-old female SHRs were randomly assigned into two groups: group SHR was control; The animal in group SHR+B was given with 10 mg/kg of benazepril perday. Another 15 Wistar rats with the same age and sex were normal control (group Wistar). After 12 weeks of pretreatment, all rats in each group were subjected to 30 min of left anterior descending coronary artery occlusion and 30 min of reperfusion. Hemodynamic parameters, left heart-to-body weight ratio(LVW/BW), myocardial malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and SR Ca~(2+)-ATPase activity were measured. RESULTS: Compared to group Wistar, the rats in group SHR had higher blood pressure, LVW/BW and myocardial MDA concentration, more serious left cardiac function injury and lower myocardial SOD activity and SR Ca~(2+)-ATPase activity; group SHR+B had lower myocardial MDA concentration, higher myocardial SOD activity, but no difference in blood pressure, LVW/BW, the degree of left cardiac function injury and myocardial SR Ca~(2+)-ATPase activity. CONCLUSION: Benazepril can attenuate ischemia-reperfusion-induced cardiac function injury by regression of left ventricular hypertrophy (LVH), improving SR Ca~(2+)-ATPase activity and decreasing oxygen free radicals injury in SHRs.