Liver tissue changes induced by biological and chemical silver nanoparticles in trained male Wistar rats

INTRODUCTION

Despite the widespread use of chemical and biological nano-silver are in industry, their side effects on hepatocytes have been less studied. On the other hand, different types of physical activities may increase liver resistance to toxins. Therefore, the aim of this study was to evaluate the resistance of hepatocytes to receiving chemical versus biological silver nanoparticles in aerobic and anaerobic pre-conditioned rats.

MATERIALS AND METHODS

45 male Wistar rats with similar average range of age (8-12 weeks) and weight (180-220 g), were randomly divided normally into 9 groups, including Control (C), Aerobic (A), Anaerobic (AN), Biological nano-silver (BNS), Chemical nano-silver (CNS), Biological nano-silver + Aerobic (BNS+A), Biological nano-silver + Anaerobic (BNS+AN), Chemical nano-silver + Aerobic (CNS+A) and Chemical nano-silver + Anaerobes (CNS+AN). Prior to injection, rats trained on a rodent treadmill, 10 weeks, 3 sessions per week, according to aerobic and anaerobic protocols.Then, 48 h after the last training session, the rats received 10 % of their body weight, chemical and biological nanosilver intraperitoneally. Liver enzymes (ALT, AST, and ALP) and liver tissue were sent to the relevant laboratories for further evaluation.

RESULTS

Results showed that the weight of rats in all groups of physical pre-conditioning, decreased comparison to the control and non-exercise groups, and this decrease was much greater in the anaerobic group (p-value=0.045). Also, the distance traveled in the progressive endurance running a test on a rodent treadmill, increased significantly in the training groups compared to the nano-exercise and control groups (p-value=0.001). Also, the results showed that the level of ALT in chemical nano-silver (p-value=0.004) and biological nano-silver (p-value=0.044), increased significantly compared to other groups. Also, histopathological results showed that nano-silver injection affects the structure of the liver of male Wistar rats and causes inflammation, hyperemia and destruction of liver cells, especially in chemical nano-silver.

CONCLUSION

The results of the present study showed that chemical silver nanoparticles cause liver damage more than comparison biological ones. Also, physical pre-conditioning increases hepatocyte resistance to toxic nanoparticle doses and aerobic preparation appears to be more effective than anaerobic.

Recent advances in pre-conditioned mesenchymal stem/stromal cell (MSCs) therapy in organ failure; a comprehensive review of preclinical studies

Mesenchymal stem/stromal cells (MSCs)-based therapy brings the reassuring capability to regenerative medicine through their self-renewal and multilineage potency. Also, they secret a diversity of mediators, which are complicated in moderation of deregulated immune responses, and yielding angiogenesis in vivo. Nonetheless, MSCs may lose biological performance after procurement and prolonged expansion in vitro. Also, following transplantation and migration to target tissue, they encounter a harsh milieu accompanied by death signals because of the lack of proper tensegrity structure between the cells and matrix. Accordingly, pre-conditioning of MSCs is strongly suggested to upgrade their performances in vivo, leading to more favored transplantation efficacy in regenerative medicine. Indeed, MSCs ex vivo pre-conditioning by hypoxia, inflammatory stimulus, or other factors/conditions may stimulate their survival, proliferation, migration, exosome secretion, and pro-angiogenic and anti-inflammatory characteristics in vivo. In this review, we deliver an overview of the pre-conditioning methods that are considered a strategy for improving the therapeutic efficacy of MSCs in organ failures, in particular, renal, heart, lung, and liver.

The mechanistic basis and adaptive significance of cross-tolerance: a 'pre-adaptation' to a changing world?

Protective responses are pivotal in aiding organismal persistence in complex, multi-stressor environments. Multiple-stressor research has traditionally focused on the deleterious effects of exposure to concurrent stressors. However, encountering one stressor can sometimes confer heightened tolerance to a second stressor, a phenomenon termed 'cross-protection'. Cross-protection has been documented in a wide diversity of taxa (spanning the bacteria, fungi, plant and animal kingdoms) and habitats (intertidal, freshwater, rainforests and polar zones) in response to many stressors (e.g. hypoxia, predation, desiccation, pathogens, crowding, salinity, food limitation). Remarkably, cross-protection benefits have also been shown among emerging, anthropogenic stressors, such as heatwaves and microplastics. In this Commentary, we discuss the mechanistic basis and adaptive significance of cross-protection, and put forth the idea that cross-protection will act as a 'pre-adaptation' to a changing world. We highlight the critical role that experimental biology has played in disentangling stressor interactions and provide advice for enhancing the ecological realism of laboratory studies. Moving forward, research will benefit from a greater focus on quantifying the longevity of cross-protection responses and the costs associated with this protective response. This approach will enable us to make robust predictions of species' responses to complex environments, without making the erroneous assumption that all stress is deleterious.

Priming with caffeic acid enhances the potential and survival ability of human adipose-derived stem cells to counteract hypoxia

The therapeutic effectiveness of stem cells after transplantation is hampered by the hypoxic milieu of chronic wounds. Prior research has established antioxidant priming as a thorough plan to improve stem cell performance. The purpose of this study was to ascertain how caffeic acid (CA) priming affected the ability of human adipose-derived stem cells (hASCs) to function under hypoxic stress. In order to study the cytoprotective properties of CA, hASCs were primed with CA in CoCl₂ hypoxic conditions. Microscopy was used to assess cell morphology, while XTT, Trypan Blue, X-gal, LDH, Live Dead, scratch wound healing, and ROS assays were used to analyze viability, senescence, cell death, proliferation, and reactive oxygen species prevalence in the cells. According to our findings, CA priming enhances hASCs' ability to survive and regenerate in a hypoxic microenvironment more effectively than untreated hASCs. Our in-vitro research suggested that pre-treatment with CA of hASCs could be a unique way to enhance their therapeutic efficacy and ability to survive in hypoxic microenvironments.

Anoxia hormesis improves performance and longevity at the expense of fitness in a classic life history trade-off

Hormesis occurs as a result of biphasic dose relationship resulting in stimulatory responses at low doses and inhibitory ones at high doses. In this framework, environmental factors are often studied to understand how this exposure benefits the animal. In the current study we used anoxia, the total absence of oxygen, as the most extreme version of low oxygen hormesis. Our goal was to determine the dose, the extent of the effect, and the cost of that response in Tenebrio molitor. We identified that the hormetic range (1 to 3 h of anoxia) was similar to that of other insects. Individuals that were exposed to 3 h had high emergence, increased activity throughout life, and lived longer. Beetles that experienced 1 h of anoxia performed better than the controls while the 6-h group had compromised performance. These boosts in performance at 3 h were accompanied by significant costs. Treated individuals had a delay in development and once matured they had decreased fitness. There were also transgenerational effects of hormesis and F₁ beetles also experienced a delay in development. Additionally, the F₁ generation had decreased developmental completion (i.e., stress-induced developmental halt). Our data suggests that anoxia hormesis triggers a trade-off where individuals benefiting from improved performance and living longer experience a decrease in reproduction.

Mesenchymal stem cell-derived exosomes: The dawn of diabetic wound healing

Chronic wound healing has long been an unmet medical need in the field of wound repair, with diabetes being one of the major etiologies. Diabetic chronic wounds (DCWs), especially diabetic foot ulcers, are one of the most threatening chronic complications of diabetes. Although the treatment strategies, drugs, and dressings for DCWs have made great progress, they remain ineffective in some patients with refractory wounds. Stem cell-based therapies have achieved specific efficacy in various fields, with mesenchymal stem cells (MSCs) being the most widely used. Although MSCs have achieved good feedback in preclinical studies and clinical trials in the treatment of cutaneous wounds or other situations, the potential safety concerns associated with allogeneic/autologous stem cells and unknown long-term health effects need further attention and supervision. Recent studies have reported that stem cells mainly exert their trauma repair effects through paracrine secretion, and exosomes play an important role in intercellular communication as their main bioactive component. MSC-derived exosomes (MSC-Exos) inherit the powerful inflammation and immune modulation, angiogenesis, cell proliferation and migration promotion, oxidative stress alleviation, collagen remodeling imbalances regulation of their parental cells, and can avoid the potential risks of direct stem cell transplantation to a large extent, thus demonstrating promising performance as novel "cell-free" therapies in chronic wounds. This review aimed to elucidate the potential mechanism and update the progress of MSC-Exos in DCW healing, thereby providing new therapeutic directions for DCWs that are difficult to be cured using conventional therapy.

The influence of warm-up duration on simulated rugby league interchange match performance

OBJECTIVE

The study was conducted to understand the effects of a short (10 min) and a long (30 min) duration warm-up on subsequent readiness to exercise and movement during simulated rugby league match play. Methods: Using a randomised cross-over design, 13 male rugby players (age: 23.6 ± 4.1 y) completed 10- or 30-min warm-up immediately before 2 × 23 min rugby league movement simulation protocol. Results: Total distance, high- and low speed running and tympanic temperature (ES = 0.56 to 20.8) were all higher in the 30 min warm-up, with differences in relative distance and heart rate unclear (ES = -0.36 to 0.06). Differences in participants' readiness to exercise after the warm-ups were unclear (ES = 0.25). Differences between trials for movement characteristics (ES = -0.13 to -0.32), RPE (ES = -0.13 to 0.04) and B[La] after the simulation were mostly unclear, with only trivial changes in high-speed running (ES = 0.08) and a lower heart rate (ES = -0.26) between the two playing bouts after the 30 min warm-up trial. Conclusion: Practitioners can use warm-ups between 10 or 30 minutes for rugby league interchange players without any implications for subsequent match running performance.

Lipopolysaccharide Pre-conditioning Attenuates Pro-inflammatory Responses and Promotes Cytoprotective Effect in Differentiated PC12 Cell Lines via Pre-activation of Toll-Like Receptor-4 Signaling Pathway Leading to the Inhibition of Caspase-3/Nuclear Factor-κappa B Pathway

Lipopolysacharide (LPS) pre-conditioning (PC), has been shown to exert protective effects against cytotoxic effects. Therefore, we hypothesized, the tolerance produced by LPS PC will be resulted by the alterations and modifications in gene and protein expression. With reference to the results of MTT assays, AO/PI staining, and Annexin V-FITC analyses of LPS concentration (0.7815-50 μg/mL) and time-dependent (12-72 h) experiments, the pre-exposure to 3 μg/mL LPS for 12 h protected the differentiated PC12 cells against 0.75 mg/mL LPS apoptotic concentration. LPS-treated cells secreted more inflammatory cytokines like IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-6, IL-17, IFN-γ, and TNF-α than LPS-PC cells. The production of inflammatory mediators ROS and NO was also higher in the LPS-induced cells compared to LPS-PC cells. Conversely, anti-inflammatory cytokines (like IL-10, IL-13, CNTF, and IL-1Ra) were upregulated in the LPS-PC cells but not in the LPS-induced cells. Meanwhile, the LPS initiated caspase-8 which in turn activates effector caspase 3/7. When the activities of caspases in the LPS-induced cells were inhibited using z-VADfmk and z-DEVDfmk, the expressions of c-MYC and Hsp70 were increased, but p53 was reduced. The potential molecules associated with protective and destructive effect was measured by RT² Profiler PCR array to elucidate the signaling pathways and suggested inhibition NF-κB/caspase-3 signaling pathway regulates the cytoprotective genes and proto-oncogenes. In conclusion, this study provides a basis for future research to better understand the molecular mechanism underlying LPS pre-conditioning /TLR4 pre-activation and its functional role in offering cytoprotective response in neuronal environment.

Abiotic contexts consistently influence mycorrhiza functioning independently of the composition of synthetic arbuscular mycorrhizal fungal communities

The relationship between mycorrhiza functioning and composition of arbuscular mycorrhizal (AM) fungal communities is an important but experimentally still rather little explored topic. The main aim of this study was thus to link magnitude of plant benefits from AM symbiosis in different abiotic contexts with quantitative changes in AM fungal community composition. A synthetic AM fungal community inoculated to the model host plant Medicago truncatula was exposed to four different abiotic contexts, namely drought, elevated phosphorus availability, and shading, as compared to standard cultivation conditions, for two cultivation cycles. Growth and phosphorus uptake of the host plants was evaluated along with the quantitative composition of the synthetic AM fungal community. Abiotic context consistently influenced mycorrhiza functioning in terms of plant benefits, and the effects were clearly linked to the P requirement of non-inoculated control plants. In contrast, the abiotic context only had a small and transient effect on the quantitative AM fungal community composition. Our findings suggest no relationship between the degree of mutualism in AM symbiosis and the relative abundances of AM fungal species in communities in our simplified model system. The observed progressive dominance of one AM fungal species indicates an important role of different growth rates of AM fungal species for the establishment of AM fungal communities in simplified systems such as agroecosystems.

The protective effect of epigallocatechin 3-gallate on mouse pancreatic islets via the Nrf2 pathway

PURPOSE

Epigallocatechin 3-gallate (EGCG), a green tea polyphenol, has been shown to have anti-oxidant and anti-inflammatory effects in vitro and in vivo. The aim of this study was to investigate the effects and mechanism of EGCG on isolated pancreatic islets as pre-conditioning for pancreatic islet transplantation.

METHODS

The pancreatic islets were divided into two groups: an islet culture medium group (control) and an islet culture medium with EGCG (100 µM) group. We investigated the islet viability, Nrf2 expression, reactive oxygen species (ROS) production, and heme oxygenase-1 (HO-1) mRNA. Five hundred islet equivalents after 12 h of culture for the EGCG 100 µM and control group were transplanted under the kidney capsule of streptozotocin-induced diabetic ICR mice.

RESULTS

The cell viability and insulin secretion ability in the EGCG group were preserved, and the nuclear translocation of Nrf2 was increased in the EGCG group (p < 0.01). While the HO-1 mRNA levels were also higher in the EGCG group than in the control group (p < 0.05), the ROS production was lower (p < 0.01). An in vivo functional assessment showed that the blood glucose level had decreased in the EGCG group after transplantation (p < 0.01).

CONCLUSION

EGCG protects the viability and function of islets by suppressing ROS production via the Nrf2 pathway.

Complete blood count data and leukocyte expression of cytokine genes and cytokine receptor genes associated with bovine respiratory disease in calves

OBJECTIVE

The purpose of this study was to evaluate potential relationships between cytokine gene expression, complete blood counts (CBC) and animals that were sick or would become sick. The CBC and the transcript abundance of cytokines and their receptors expressed in leukocytes were measured from calves at two early timepoints, and again after diagnosis with bovine respiratory disease (BRD).

RESULTS

Blood was collected from calves at pre-conditioning (n = 796) and weaning (n = 791) for CBC. Blood counts were also measured for the calves with BRD (n = 13), and asymptomatic calves (n = 75) after weaning. The CBC were compared for these animals at 3 time points. At diagnosis, neutrophils were higher and basophils lower in sick animals (P < 0.05). To further characterize BRD responses, transcript abundance of 84 cytokine genes were evaluated in 5 calves with BRD and 9 asymptomatic animals at all time points. There was more data for CBC than transcript abundance; hence, animal and temporary environmental correlations between CBC and transcript abundance were exploited to improve the power of the transcript abundance data. Expression of CCL16, CXCR1, CCR1 was increased in BRD positive animals compared to controls (P-corrected < 0.1). Cytokine expression data may help to provide insight into an animal's health.

Survival and Infectivity of Entomopathogenic Nematodes Formulated in Sodium Alginate Beads

An alternative control method to the use of chemical insecticides against soil dwelling insect pests is the application of entomopathogenic nematodes formulated in alginate beads for enhanced shelf life. The aim was to compare the benefit on nematode survival and infectivity of: (i) pre-conditioning of juveniles, and (ii) coating of alginate beads. The nematodes Steinernema glaseri , Steinernema carpocapsae, and Heterorhabditis bacteriophora were reproduced in last instar larvae of the wax moth Galleria mellonella and the infective juveniles emerged were subjected to two capture treatments: white traps and plaster of Paris, the latter was utilized as a pre-conditioning treatment. A total of 1,000 infective juveniles were formulated in each sodium alginate bead with or without an alginate coating. The beads were stored at 23 ± 3°C and a bidistilled water suspension of nematodes was set as a control. The survivorship of these formulates and their infectivity on Galleria mellonella larvae were evaluated every 7 d post-formulation (dpf). In beads without pre-conditioning juveniles nor coating, Steinernema carpocapsae had the higher survival rate (58.8%), the longest survival time (28 dpf) and the higher infectivity (100%) as well. Pre-conditioning improved the survival and infectivity of Steinernema glaseri by 22.5% at 21 dpf and 70.0% at 14 dpf, respectively. Alginate coating increased survival (21.7%) and infectivity (95%) of Heterorhabditis bacteriophora for up to 28 dpf. The combination of pre-conditioning and coating slightly favored the survival (10% for up to 14 dpf) of Steinernema glaseri and infectivity (100% for up to 35 dpf) of Steinernema carpocapsae . Non pre-conditioned Steinernema carpocapsae formulated in uncoated beads was the combination with better performance in survivorship (58.8%) and infectivity (100%) at 28 dpf. It was concluded that non pre-conditioned Steinernema carpocapsae formulated in uncoated beads was the combination with better survivorship and infectivity.

Role of transglutaminase 2 in A1 adenosine receptor- and β2-adrenoceptor-mediated pharmacological pre- and post-conditioning against hypoxia-reoxygenation-induced cell death in H9c2 cells

Pharmacologically-induced pre- and post-conditioning represent attractive therapeutic strategies to reduce ischaemia/reperfusion injury during cardiac surgery and following myocardial infarction. We have previously reported that transglutaminase 2 (TG2) activity is modulated by the A₁ adenosine receptor and β₂-adrenoceptor in H9c2 cardiomyoblasts. The primary aim of this study was to determine the role of TG2 in A₁ adenosine receptor and β₂-adrenoceptor-induced pharmacological pre- and post-conditioning in the H9c2 cells. H9c2 cells were exposed to 8h hypoxia (1% O₂) followed by 18h reoxygenation, after which cell viability was assessed by monitoring mitochondrial reduction of MTT, lactate dehydrogenase release and caspase-3 activation. N⁶-cyclopentyladenosine (CPA; A₁ adenosine receptor agonist), formoterol (β₂-adrenoceptor agonist) or isoprenaline (non-selective β-adrenoceptor agonist) were added before hypoxia/reoxygenation (pre-conditioning) or at the start of reoxygenation following hypoxia (post-conditioning). Pharmacological pre- and post-conditioning with CPA and isoprenaline significantly reduced hypoxia/reoxygenation-induced cell death. In contrast, formoterol did not elicit protection. Pre-treatment with pertussis toxin (G_i/o-protein inhibitor), DPCPX (A₁ adenosine receptor antagonist) or TG2 inhibitors (Z-DON and R283) attenuated the A₁ adenosine receptor-induced pharmacological pre- and post-conditioning. Similarly, pertussis toxin, ICI 118,551 (β₂-adrenoceptor antagonist) or TG2 inhibition attenuated the isoprenaline-induced cell survival. Knockdown of TG2 using small interfering RNA (siRNA) attenuated CPA and isoprenaline-induced pharmacological pre- and post-conditioning. Finally, proteomic analysis following isoprenaline treatment identified known (e.g. protein S100-A6) and novel (e.g. adenine phosphoribosyltransferase) protein substrates for TG2. These results have shown that A₁ adenosine receptor and β₂-adrenoceptor-induced protection against simulated hypoxia/reoxygenation occurs in a TG2 and G_i/o-protein dependent manner in H9c2 cardiomyoblasts.

Stem cell transplantation therapy for multifaceted therapeutic benefits after stroke

One of the exciting advances in modern medicine and life science is cell-based neurovascular regeneration of damaged brain tissues and repair of neuronal structures. The progress in stem cell biology and creation of adult induced pluripotent stem (iPS) cells has significantly improved basic and pre-clinical research in disease mechanisms and generated enthusiasm for potential applications in the treatment of central nervous system (CNS) diseases including stroke. Endogenous neural stem cells and cultured stem cells are capable of self-renewal and give rise to virtually all types of cells essential for the makeup of neuronal structures. Meanwhile, stem cells and neural progenitor cells are well-known for their potential for trophic support after transplantation into the ischemic brain. Thus, stem cell-based therapies provide an attractive future for protecting and repairing damaged brain tissues after injury and in various disease states. Moreover, basic research on naïve and differentiated stem cells including iPS cells has markedly improved our understanding of cellular and molecular mechanisms of neurological disorders, and provides a platform for the discovery of novel drug targets. The latest advances indicate that combinatorial approaches using cell based therapy with additional treatments such as protective reagents, preconditioning strategies and rehabilitation therapy can significantly improve therapeutic benefits. In this review, we will discuss the characteristics of cell therapy in different ischemic models and the application of stem cells and progenitor cells as regenerative medicine for the treatment of stroke.

Risk factors for lower leg, ankle and foot injuries during basic military training in the Maltese Armed Forces

OBJECTIVES

Basic military training is physically and psychologically demanding placing recruits at high risk of injury and premature discharge. This study aimed to identify risk factors for lower leg, ankle and foot injury in Maltese military recruits during basic training.

DESIGN

This was a prospective cohort study.

SETTING

An armed forces barracks.

PARTICIPANTS

127 recruits commencing one basic military training course agreed to participate in the study. The cohort comprised 114 males and 13 females with a mean age of 21.7 ± 2.4 years.

MAIN OUTCOME MEASURES

All injuries to the lower leg, ankle and foot were recorded using the Orchard Sports Injury Classification System. Injuries were analysed for associations with fitness scores, smoking status, body mass index and foot type.

RESULTS

A total of 34 (26.2%) recruits sustained at least one injury, with 10 recruits (7.9%) terminating their training prematurely (three due to musculoskeletal injury). Smoking history, body mass index and foot type were not associated with injury risk. Lower fitness levels at the commencement of basic military training compared with fitness levels measured six months prior, were associated with higher injury risk.

CONCLUSIONS

Lower fitness at the commencement of basic training was associated with higher injury risk in army recruits. Thus, conditioning programmes aimed at improving recruit fitness should be considered within an injury prevention strategy.

A comparative analysis of C57BL/6J and 6N substrains; chemokine/cytokine expression and susceptibility to laser-induced choroidal neovascularization

Age-related macular degeneration (AMD) is the most prevalent cause of blindness in the elderly. To study potential underlying mechanisms of AMD, animal models are utilized, focusing mostly on mice. Recently, genomic and phenotypic differences between the so-called control substrains, C57BL/6J and C57BL/6N, have been described in models of ocular and non-ocular diseases. In particular, the rd8 mutation of the Crb1 gene present in the C57BL/6N has been shown to impact certain ocular phenotypes and appears to augment phenotypes generally associated with inflammation. Here, we investigated angiogenic factor and cytokine expression using pathway arrays as well as the susceptibility to laser-induced choroidal neovascularization (CNV), a model of wet AMD, in the two substrains. Age-matched 3-month-old C57BL/6J and C57BL/6N animals differed in gene expression levels for angiogenic factors and cytokines, with 6N animals expressing higher levels of inflammatory markers than 6Js. Yet laser-induced CNV was comparable in size between the two substrains. This lack of difference in CNV size was correlated with a gene expression profile that was comparable between the two substrains, due to the fact that the degree of change in gene expression of inflammatory markers after CNV was blunted in 6N mice. In summary, significant gene expression differences exist between C57BL/6J and C57BL/6N animals, reinforcing the notion that appropriate litter-mate controls or genetic background controls need to be used. Contrary to our expectation, CNV was not augmented in 6N animals, suggesting that low chronic inflammation in the RPE might provide a level of pre-conditioning and protection against stress.

"Preconditioning" with latrepirdine, an adenosine 5'-monophosphate-activated protein kinase activator, delays amyotrophic lateral sclerosis progression in SOD1(G93A) mice

Adenosine 5'-monophosphate-activated protein kinase (AMPK) is a master regulator of energy balance. As energy imbalance is documented as a key pathologic feature of amyotrophic lateral sclerosis (ALS), we investigated AMPK as a pharmacologic target in SOD1(G93A) mice. We noted a strong activation of AMPK in lumbar spinal cords of SOD1(G93A) mice. Pharmacologic activation of AMPK has shown protective effects in neuronal "preconditioning" models. We tested the hypothesis that "preconditioning" with a small molecule activator of AMPK, latrepirdine, exerts beneficial effects on disease progression. SOD1(G93A) mice (n = 24 animals per group; sex and litter matched) were treated with latrepirdine (1 μg/kg, intraperitoneal) or vehicle from postnatal day 70 to 120. Treatment with latrepirdine increased AMPK activity in primary mouse motor neuron cultures and in SOD1(G93A) lumbar spinal cords. Mice "preconditioned" with latrepirdine showed a delayed symptom onset and a significant increase in life span (p < 0.01). Our study suggests that "preconditioning" with latrepirdine may represent a possible therapeutic strategy for individuals harboring ALS-associated gene mutations who are at risk for developing ALS.

Pre-conditioning with low-level laser (light) therapy: light before the storm

Pre-conditioning by ischemia, hyperthermia, hypothermia, hyperbaric oxygen (and numerous other modalities) is a rapidly growing area of investigation that is used in pathological conditions where tissue damage may be expected. The damage caused by surgery, heart attack, or stroke can be mitigated by pre-treating the local or distant tissue with low levels of a stress-inducing stimulus, that can induce a protective response against subsequent major damage. Low-level laser (light) therapy (LLLT) has been used for nearly 50 years to enhance tissue healing and to relieve pain, inflammation and swelling. The photons are absorbed in cytochrome(c) oxidase (unit four in the mitochondrial respiratory chain), and this enzyme activation increases electron transport, respiration, oxygen consumption and ATP production. A complex signaling cascade is initiated leading to activation of transcription factors and up- and down-regulation of numerous genes. Recently it has become apparent that LLLT can also be effective if delivered to normal cells or tissue before the actual insult or trauma, in a pre-conditioning mode. Muscles are protected, nerves feel less pain, and LLLT can protect against a subsequent heart attack. These examples point the way to wider use of LLLT as a pre-conditioning modality to prevent pain and increase healing after surgical/medical procedures and possibly to increase athletic performance.

Redox therapeutics in hepatic ischemia reperfusion injury

Ischemia-reperfusion plays a major role in the injury experienced by the liver during transplantation. Much work has been done recently investigating the role of redox species in hepatic ischemia-reperfusion. As animal models are better characterized and developed, and more insights are gained into the pathophysiology of hepatic ischemia reperfusion injury in humans the questions into exactly how oxidants participate in this injury are becoming more refined. These questions include effects of cellular location, timing of injury, and ability of therapeutics to access this site are increasing our appreciation of the complexity of ischemia reperfusion and improving attempts to ameliorate its effects. In this review, we aim to discuss the various methods to alter redox chemistry during ischemia reperfusion injury and future prospects for preventing organ injury during hepatic ischemia reperfusion.

Nitrite activates protein kinase A in normoxia to mediate mitochondrial fusion and tolerance to ischaemia/reperfusion

AIMS

Nitrite (NO2(-)), a dietary constituent and nitric oxide (NO) oxidation product, mediates cardioprotection after ischaemia/reperfusion (I/R) in a number of animal models when administered during ischaemia or as a pre-conditioning agent hours to days prior to the ischaemic episode. When present during ischaemia, the reduction of nitrite to bioactive NO by deoxygenated haem proteins accounts for its protective effects. However, the mechanism of nitrite-induced pre-conditioning, a normoxic response which does not appear to require reduction of nitrite to NO, remains unexplored.

METHODS AND RESULTS

Using a model of hypoxia/reoxygenation (H/R) in cultured rat H9c2 cardiomyocytes, we demonstrate that a transient (30 min) normoxic nitrite treatment significantly attenuates cell death after a hypoxic episode initiated 1 h later. Mechanistically, this protection depends on the activation of protein kinase A, which phosphorylates and inhibits dynamin-related protein 1, the predominant regulator of mitochondrial fission. This results morphologically, in the promotion of mitochondrial fusion and functionally in the augmentation of mitochondrial membrane potential and superoxide production. We identify AMP kinase (AMPK) as a downstream target of the mitochondrial reactive oxygen species (ROS) generated and show that its oxidation and subsequent phosphorylation are essential for cytoprotection, as scavenging of ROS prevents AMPK activation and inhibits nitrite-mediated protection after H/R. The protein kinase A-dependent protection mediated by nitrite is reproduced in an intact isolated rat heart model of I/R.

CONCLUSIONS

These data are the first to demonstrate nitrite-dependent normoxic modulation of both mitochondrial morphology and function and reveal a novel signalling pathway responsible for nitrite-mediated cardioprotection.