Neuroprotective effects of hyperbaric oxygen treatment in experimental focal cerebral ischemia are associated with reduced brain leukocyte myeloperoxidase activity

Benzylisoquinoline alkaloids inhibit lung fibroblast activation mainly via inhibiting TGF-β1/Smads and ERK1/2 pathway proteins

Backgrounds

Liensinine (Lien), Neferine (Nef), Isoliensinine (Iso) and Tetrandrine (Tet), benzylisoquinoline alkaloids (BIAs), have been shown inhibitory effects on pulmonary fibrosis (PF) through anti-inflammatory, anti-oxidative activities, inhibition of cytokines and NF-κB. Effects of other similar BIAs, Dauricine (Dau), Papaverine (Pap) and lotusine (Lot), on PF remain unclear. Here, we explored the effects of five bisbenzylisoquinoline (Lien, Nef, Iso, Tet and Dau) and two monobenzylisoquinoline (Pap, Lot) alkaloids on normal and PF fibroblasts.

Methods

Primary normal and PF lung fibroblasts were cultured and treated with these alkaloids. Proliferation, activation, migration and apoptosis changes were detected by MTT, wound healing assay, flow cytometry. Protein level was analyzed by Western blot.

Results

All BIAs inhibited proliferation of normal and PF lung fibroblasts induced by TGF-β. α-SMA protein level in normal and PF lung fibroblasts decreased after Lien, Nef, Iso, Tet and Dau treatment. Pap and Lot had no influence on α-SMA expression. Dau showed the strongest inhibitory effects on proliferation and activation among alkaloids. The migration rates of normal and PF lung fibroblasts were inhibited by Lien, Nef, Iso, and Dau. Lien, Nef, Iso and Dau significantly promoted apoptosis, while Tet had no effect on apoptosis. Pap and Lot had no influence on activation, migration and apoptosis. Dau significantly inhibited Smad3/4 and p-ERK1/2 protein overexpression induced by TGF-β1.

Conclusions

Bisbenzylisoquinoline alkaloids had stronger effects on inhibiting lung fibroblasts than monobenzylisoquinoline alkaloids. Dau expressed the strongest inhibitory effects, which may be related to its inhibition of TGF-β1/Smad3/4 and p-ERK1/2 pathway proteins.

A novel fluorescent probe with large Stokes shift for accurate detection of HOCl in mitochondria and its imaging application

Hypochlorous acid (HOCl), mainly generated in mitochondria, plays a critical role in various physiological processes. To better understand the role and function of HOCl in mitochondria, herein, we present the design and synthesis of a Mito-QL reporter for probing the HOCl within mitochondria without other interference generated in living cells. Through the combination of TICT/ICT mechanisms, probe Mito-QL, with large stokes shift (203 nm) and low background fluorescence, exhibited excellent sensitivity (900-fold fluorescence enhancement) and selectivity towards HOCl (LOD = 2.4 nM). The co-location experiments confirmed that probe Mito-QL can firstly localize in the mitochondria and then react with HOCl in mitochondria. Also, the probe is capable of imaging endogenous and exogenous HOCl even the generation of HOCl during the ferroptosis of cells, which is beneficial for more efficient application in biological imaging.

Pituitary Adenylate Cyclase-Activating Polypeptide: A Potent Therapeutic Agent in Oxidative Stress

Stroke is a life-threatening condition that is characterized by secondary cell death processes that occur after the initial disruption of blood flow to the brain. The inability of endogenous repair mechanisms to sufficiently support functional recovery in stroke patients and the inadequate treatment options available are cause for concern. The pathology behind oxidative stress in stroke is of particular interest due to its detrimental effects on the brain. The oxidative stress caused by ischemic stroke overwhelms the neutralization capacity of the body's endogenous antioxidant system, which leads to an overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and eventually results in cell death. The overproduction of ROS compromises the functional and structural integrity of brain tissue. Therefore, it is essential to investigate the mechanisms involved in oxidative stress to help obtain adequate treatment options for stroke. Here, we focus on the latest preclinical research that details the mechanisms behind secondary cell death processes that cause many central nervous system (CNS) disorders, as well as research that relates to how the neuroprotective molecular mechanisms of pituitary adenylate cyclase-activating polypeptides (PACAPs) could make these molecules an ideal candidate for the treatment of stroke.

Effects of hyperbaric oxygen therapy on the healing of thermal burns and its relationship with ICAM-1: A case-control study

BACKGROUND

The damaging effects of thermal burns need to be managed holistically in order to create a suitable environment for wound healing. The purpose of our study was to investigate the effects of hyperbaric oxygen therapy (HBOT) on the healing of thermal burns and its relationship with intercellular adhesion molecule 1 (ICAM-1).

METHODS

Twenty patients with thermal burns were randomly divided into two groups: the group to receive HBOT and the control group. Levels of the ICAM-1 mRNA gene and ICAM-1 serum along with the degree of wound epithelialization were examined before and after treatment. Laboratory and physical findings between the groups were compared.

RESULTS

In the HBOT group compared with the control group, thermal wound complications were significantly reduced (p = .006), while length of stay in hospital was substantially reduced (p = .001). ICAM-1 serum levels strongly correlated with ICAM-1 mRNA gene expression (R 2 = 0.909, p < .001). The expression of the ICAM-1 mRNA gene (12.32 ± 1.31 vs. 10.79 ± 1.38) and ICAM-1 serum level (231.46 ± 37.20 vs. 158.23 ± 68.30) in patients with at least a 50% burn area exceeded those of patients with a smaller burn area. HBOT significantly decreased (p < .05) the expression of the ICAM-1 mRNA gene and ICAM-1 serum level (p = .004). The number of HBOT sessions strongly correlated with ICAM-1 serum level (p = .043) but poorly correlated with ICAM-1 mRNA gene expression (p = .22). The expression of the gene, however, strongly correlated with ICAM-1 serum level (r = -0.988, p < .001).

CONCLUSION

HBOT can reduce thermal wound complications, length of stay in hospitals due to thermal burns, ICAM-1 mRNA gene expression, and ICAM-1 serum level.

An Extra Breath of Fresh Air: Hyperbaric Oxygenation as a Stroke Therapeutic

Stroke serves as a life-threatening disease and continues to face many challenges in the development of safe and effective therapeutic options. The use of hyperbaric oxygen therapy (HBOT) demonstrates pre-clinical effectiveness for the treatment of acute ischemic stroke and reports reductions in oxidative stress, inflammation, and neural apoptosis. These pathophysiological benefits contribute to improved functional recovery. Current pre-clinical and clinical studies are testing the applications of HBOT for stroke neuroprotection, including its use as a preconditioning regimen. Mild oxidative stress may be able to prime the brain to tolerate full extensive oxidative stress that occurs during a stroke, and HBOT preconditioning has displayed efficacy in establishing such ischemic tolerance. In this review, evidence on the use of HBOT following an ischemic stroke is examined, and the potential for HBOT preconditioning as a neuroprotective strategy. Additionally, HBOT as a stem cell preconditioning is also discussed as a promising strategy, thus maximizing the use of HBOT for ischemic stroke.

The effects of hyperbaric oxygen therapy on the brain with middle cerebral artery occlusion

Middle cerebral artery occlusion (MCAO) causes focal cerebral hypoperfusion, resulting in cerebral ischemia or ischemic stroke. The main therapeutic approach is to restore an adequate blood flow to the brain via the process of reperfusion. However, rapid reperfusion can itself aggravate brain damage; this adverse effect is known as ischemic/reperfusion (I/R) injury. The pathological conditions that occur after cerebral ischemia and cerebral I/R are microvascular injury, blood-brain barrier dysfunction, post-ischemic inflammation, increased oxidative stress/reactive oxygen species, and a reduction in neuronal survival, leading to brain infarction. Animal and clinical studies on hyperbaric oxygen therapy (HBOT) have recently been carried out, and there is evidence of positive effects on neurological outcomes after cerebral ischemia. However, some evidence has shown that HBOT may not affect the functional recovery after ischemic injury. This review describes the current evidence, both in vivo and clinical data, regarding the potential benefits of HBOT after MCAO and cerebral I/R injury. The contrary data are also discussed to verify the effectiveness of HBOT in stroke outcomes.

Hyperbaric oxygen and focused rehabilitation program: a feasibility study in improving upper limb motor function after stroke

Neuroplasticity and recovery after stroke can be enhanced by a rehabilitation program pertinent to upper limb motor function exercise and mental imagery (EMI) as well as hyperbaric oxygen therapy (HBOT). We assessed feasibility and safety of the combined approach utilizing both HBOT and EMI, and to derive preliminary estimates of its efficacy. In this randomized controlled trial, 27 patients with upper extremity hemiparesis at 3-48 months after stroke were randomized to receive either a complementary rehabilitation program of HBOT-EMI (intervention group), or EMI alone (control group). Feasibility and safety were assessed as total session attendance, duration of sessions, attrition rates, missing data, and intervention-related adverse events. Secondary clinical outcomes were assessed with both objective tools and self-reported measures at baseline, 8 weeks (end of treatment), and 12-weeks follow-up. Session attendance, duration, and attrition rate did not differ between the groups; there were no serious adverse events. Compared with baseline, there were significant sustained improvements of objective and subjective outcomes' measures in the intervention group, and a single improvement in an objective measure in the control group. Between-group outcome comparisons were not statistically significant. This study demonstrated that the combination HBOT-EMI was a safe and feasible approach in patients recovering from chronic stroke. There were also trends for improved motor function of the affected upper limb after the treatments. ClinicalTrials.gov registration no.: NCT02666469. Novelty HBOT combined with an upper limb exercise and mental imagery rehabilitation program is feasible and safe in chronic stroke patients. This combined approach showed trends for improved functional recovery.

Use of Gases to Treat Cochlear Conditions

Although the cochlear vascular supply (stria vascularis) is designed to block to certain compounds and molecules, it must enable gas exchange to survive. The inner ear capillaries must deliver oxygen and remove carbon dioxide for the cochlea to function. These gases diffuse through tissues across a concentration gradient to reach the desired target. Tight junctions or the endothelial basement membrane do not impede them. Therefore, gases that can diffuse into the inner ear are attractive as therapeutic agents. The two gases most often used in this way are oxygen and hydrogen, although carbon dioxide, ozone, and argon have also been investigated. Typically, oxygen is delivered as hyperbaric oxygen (HBO) (oxygen at pressure higher than atmospheric) to provide increased oxygen levels to the inner ear. This not only relieves hypoxia, but also has anti-inflammatory and other biochemical effects. HBO is used clinically to treat idiopathic sudden sensorineural hearing loss, and both animal and human studies suggest it may also assist recovery after acute acoustic trauma. Laboratory studies suggest hydrogen works as a free radical scavenger and reduces the strong oxidants hydroxyl radicals and peroxynitrite. It also has anti-apoptotic effects. Because of its anti-oxidant and anti-inflammatory effects, it has been studied as a treatment for ototoxicity and shows benefit in an animal model of cisplatinum toxicity. Gas diffusion offers an effective way to provide therapy to the inner ear, particularly since some gases (oxygen, hydrogen, carbon dioxide, ozone, argon) have important therapeutic effects for minimizing cochlear damage.

Targeting phosphodiesterase 4 as a potential therapeutic strategy for enhancing neuroplasticity following ischemic stroke

Sensorimotor recovery following ischemic stroke is highly related with structural modification and functional reorganization of residual brain tissues. Manipulations, such as treatment with small molecules, have been shown to enhance the synaptic plasticity and contribute to the recovery. Activation of the cAMP/CREB pathway is one of the pivotal approaches stimulating neuroplasticity. Phosphodiesterase 4 (PDE4) is a major enzyme controlling the hydrolysis of cAMP in the brain. Accumulating evidences have shown that inhibition of PDE4 is beneficial for the functional recovery after cerebral ischemia; i. subtype D of PDE4 (PDE4D) is viewed as a risk factor for ischemic stroke; ii. inhibition of PDE4 enhances neurological behaviors, such as learning and memory, after stroke in rodents; iii.PDE4 inhibition increases dendritic density, synaptic plasticity and neurogenesis; iv. activation of cAMP/CREB signaling by PDE4 inhibition causes an endogenous increase of BDNF, which is a potent modulator of neuroplasticity; v. PDE4 inhibition is believed to restrict neuroinflammation during ischemic stroke. Cumulatively, these findings provide a link between PDE4 inhibition and neuroplasticity after cerebral ischemia. Here, we summarized the possible roles of PDE4 inhibition in the recovery of cerebral stroke with an emphasis on neuroplasticity. We also made some recommendations for future research.

Normobaric oxygen treatment in acute ischemic stroke: a clinical perspective

Acute ischemic stroke is a common and serious neurological disease. Oxygen therapy has been shown to increase oxygen supply to ischemic tissues and improve outcomes after cerebral ischemia/reperfusion. Normobaric hyperoxia (NBO), an easily applicable and non-invasive method, shows protective effects on acute ischemic stroke animals and patients in pilot studies. However, many critical scientific questions are still unclear, such as the therapeutic time window of NBO, the long-term effects and the benefits of NBO in large clinic trials. In this article, we review the current literatures on NBO treatment of acute ischemic stroke in preclinical and clinical studies and try to analyze and identify the key gaps or unknowns in our understanding about NBO. Based on these analyses, we provide suggestions for future studies.

Hyperbaric oxygen therapy for people with autism spectrum disorder (ASD)

BACKGROUND

The rising prevalence of autism spectrum disorder (ASD) has increased the need for evidence-based treatments to lessen the impact of symptoms. Presently, no therapies are available to effectively treat individuals with all of the symptoms of this disorder. It has been suggested that hyperbaric oxygen therapy may alleviate the biochemical dysfunction and clinical symptoms of ASD.

OBJECTIVES

To determine whether treatment with hyperbaric oxygen:1. improves core symptoms of ASD, including social communication problems and stereotypical and repetitive behaviors;2. improves noncore symptoms of ASD, such as challenging behaviors;3. improves comorbid states, such as depression and anxiety; and4. causes adverse effects.

SEARCH METHODS

On 10 December 2015, we searched CENTRAL, Ovid MEDLINE, Embase, and 15 other databases, four of which were Chinese language databases. We also searched multiple trial and research registers.

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) and quasi-RCTs of any dose, duration, and frequency for hyperbaric oxygen therapy compared with no treatment or sham treatment for children and adults with ASD.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration, in that three review authors independently selected studies, assessed them for risk of bias, and extracted relevant data. We also assessed the quality of the evidence by using the GRADE approach.

MAIN RESULTS

We included one trial with a total of 60 children with a diagnosis of ASD who randomly received hyperbaric oxygen therapy or a sham treatment. Using GRADE criteria, we rated the quality of the evidence as low because of the small sample size and wide confidence intervals (CIs). Other problems included selection bias and short duration or follow-up.Overall, study authors reported no improvement in social interaction and communication, behavioral problems, communication and linguistic abilities, or cognitive function. With regard to the safety of hyperbaric oxygen therapy (adverse events), they reported minor-grade ear barotrauma events. Investigators found significant differences between groups in total number of side effect events (Peto odds ratio (OR) 3.87, 95% CI 1.53 to 9.82) and in the number of children who experienced side effects (Peto OR 4.40, 95% CI 1.33 to 14.48).

AUTHORS' CONCLUSIONS

To date, there is no evidence that hyperbaric oxygen therapy improves core symptoms and associated symptoms of ASD. It is important to note that adverse effects (minor-grade ear barotrauma events) can occur. Given the absence of evidence of effectiveness and the limited biological plausibility and possible adverse effects, the need for future RCTs of hyperbaric oxygen therapy must be carefully considered.

Hyperbaric oxygen preconditioning ameliorates blood-brain barrier damage induced by hypoxia through modulation of tight junction proteins in an in vitro model

Aim

To explore the effects of hyperbaric oxygen preconditioning (HBOP) on the permeability of blood-brain barrier (BBB) and expression of tight junction proteins under hypoxic conditions in vitro.

Methods

A BBB in vitro model was constructed using the hCMEC/D3 cell line and used when its trans-endothelial electrical resistance (TEER) reached 80-120 Ω · cm² (tested by Millicell-Electrical Resistance System). The cells were randomly divided into the control group cultured under normal conditions, the group cultured under hypoxic conditions (2%O₂) for 24 h (hypoxia group), and the group first subjected to HBOP for 2 h and then to hypoxia (HBOP group). Occludin and ZO-1 expression were analyzed by immunofluorescence assay.

Results

Normal hCMEC/D3 was spindle-shaped and tightly integrated. TEER was significantly reduced in the hypoxia (P = 0.001) and HBOP group (P = 0.014) compared to control group, with a greater decrease in the hypoxia group. Occludin membranous expression was significantly decreased in the hypoxia group (P = 0.001) compared to the control group, but there was no change in the HBOP group. ZO-1 membranous expression was significantly decreased (P = 0.002) and cytoplasmic expression was significantly increased (P = 0.001) in the hypoxia group compared to the control group, although overall expression levels did not change. In the HBOP group, there was no significant change in ZO-1 expression compared to the control group.

Conclusion

Hyperbaric oxygen preconditioning protected the integrity of BBB in an in vitro model through modulation of occludin and ZO-1 expression under hypoxic conditions.

Hyperbaric oxygen modalities are differentially effective in distinct brain ischemia models

The effectiveness and efficacy of hyperbaric oxygen (HBO) preconditioning and post-treatment modalities have been demonstrated in experimental models of ischemic cerebrovascular diseases, including global brain ischemia, transient focal and permanent focal cerebral ischemia, and experimental neonatal hypoxia-ischemia encephalopathy. In general, early and repetitive post-treatment of HBO appears to create enhanced protection against brain ischemia whereas delayed HBO treatment after transient focal ischemia may even aggravate brain injury. This review advocates the level of injury reduction upon HBO as an important component for translational evaluation of HBO based treatment modalities. The combined preconditioning and HBO post-treatment that would provide synergistic effects is also worth considering.

The Efficacy of Hyperbaric Oxygen Therapy on Middle Cerebral Artery Occlusion in Animal Studies: A Meta-Analysis

Background

Inconsistent results have been reported for hyperbaric oxygen therapy (HBO) for acute stroke. We conducted a systematic review and meta-analysis to evaluate the benefit of HBO in animal studies of middle cerebral artery occlusion (MCAO).

Methods

A systematic search of the literature published prior to September 2015 was performed using Embase, Medline (OvidSP), Web of Science and PubMed. Keywords included “hyperoxia” OR “hyperbaric oxygen” OR “HBO” AND “isch(a)emia” OR “focal cerebral ischemia” OR “stroke” OR “infarct” OR “middle cerebral artery occlusion (MCAO).” The primary endpoints were the infarct size and/or neurological outcome score evaluated after HBO treatment in MCAO. Heterogeneity was analyzed using Cochrane Library’s RevMan 5.3.5.

Results

Fifty-one studies that met the inclusion criteria were identified among the 1198 studies examined. When compared with control group data, HBO therapy resulted in infarct size reduction or improved neurological function (32% decrease in infarct size; 95% confidence interval (CI), range 28%–37%; p < 0.00001). Mortality was 18.4% in the HBO group and 26.7% in the control group (RR 0.72, 95% CI, 0.54–0.98; p = 0.03). Subgroup analysis showed that a maximal neuro-protective effect was reached when HBO was administered immediately after MCAO with an absolute atmospheric pressure (ATA) of 2.0 (50% decrease; 95% CI, 43% -57% decrease; p < 0.0001) and more than 6 hours HBO treatment (53% decrease; 95% CI, 41% -64% decrease; p = 0.0005).

Conclusions

HBO had a neuro-protective effect and improved survival in animal models of MCAO, especially in animals given more than 6 hours of HBO and when given immediately after MCAO with 2.0 ATA.

Transforming the recognition site of 4-hydroxyaniline into 4-methoxyaniline grafted onto a BODIPY core switches the selective detection of peroxynitrite to hypochlorous acid

From peroxynitrite to HOCl: two probes are reported, sharing the same BODIPY core but differing only by a minimized variation in the recognition site.

Neuroprotection in acute brain injury: an up-to-date review

Neuroprotective strategies that limit secondary tissue loss and/or improve functional outcomes have been identified in multiple animal models of ischemic, hemorrhagic, traumatic and nontraumatic cerebral lesions. However, use of these potential interventions in human randomized controlled studies has generally given disappointing results. In this paper, we summarize the current status in terms of neuroprotective strategies, both in the immediate and later stages of acute brain injury in adults. We also review potential new strategies and highlight areas for future research.

Repetitive hyperbaric oxygenation attenuates reactive astrogliosis and suppresses expression of inflammatory mediators in the rat model of brain injury

The exact mechanisms by which treatment with hyperbaric oxygen (HBOT) exerts its beneficial effects on recovery after brain injury are still unrevealed. Therefore, in this study we investigated the influence of repetitive HBOT on the reactive astrogliosis and expression of mediators of inflammation after cortical stab injury (CSI). CSI was performed on male Wistar rats, divided into control, sham, and lesioned groups with appropriate HBO. The HBOT protocol was as follows: 10 minutes of slow compression, 2.5 atmospheres absolute (ATA) for 60 minutes, and 10 minutes of slow decompression, once a day for 10 consecutive days. Data obtained using real-time polymerase chain reaction, Western blot, and immunohistochemical and immunofluorescence analyses revealed that repetitive HBOT applied after the CSI attenuates reactive astrogliosis and glial scarring, and reduces expression of GFAP (glial fibrillary acidic protein), vimentin, and ICAM-1 (intercellular adhesion molecule-1) both at gene and tissue levels. In addition, HBOT prevents expression of CD40 and its ligand CD40L on microglia, neutrophils, cortical neurons, and reactive astrocytes. Accordingly, repetitive HBOT, by prevention of glial scarring and limiting of expression of inflammatory mediators, supports formation of more permissive environment for repair and regeneration.

Very-late-antigen-4 (VLA-4)-mediated brain invasion by neutrophils leads to interactions with microglia, increased ischemic injury and impaired behavior in experimental stroke

Neuronal injury from ischemic stroke is aggravated by invading peripheral immune cells. Early infiltrates of neutrophil granulocytes and T-cells influence the outcome of stroke. So far, however, neither the timing nor the cellular dynamics of neutrophil entry, its consequences for the invaded brain area, or the relative importance of T-cells has been extensively studied in an intravital setting. Here, we have used intravital two-photon microscopy to document neutrophils and brain-resident microglia in mice after induction of experimental stroke. We demonstrated that neutrophils immediately rolled, firmly adhered, and transmigrated at sites of endothelial activation in stroke-affected brain areas. The ensuing neutrophil invasion was associated with local blood-brain barrier breakdown and infarct formation. Brain-resident microglia recognized both endothelial damage and neutrophil invasion. In a cooperative manner, they formed cytoplasmic processes to physically shield activated endothelia and trap infiltrating neutrophils. Interestingly, the systemic blockade of very-late-antigen-4 immediately and very effectively inhibited the endothelial interaction and brain entry of neutrophils. This treatment thereby strongly reduced the ischemic tissue injury and effectively protected the mice from stroke-associated behavioral impairment. Behavioral preservation was also equally well achieved with the antibody-mediated depletion of myeloid cells or specifically neutrophils. In contrast, T-cell depletion more effectively reduced the infarct volume without improving the behavioral performance. Thus, neutrophil invasion of the ischemic brain is rapid, massive, and a key mediator of functional impairment, while peripheral T-cells promote brain damage. Acutely depleting T-cells and inhibiting brain infiltration of neutrophils might, therefore, be a powerful early stroke treatment.

Should the STAIR criteria be modified for preconditioning studies?

Diverse preconditioning (PC) stimuli protect against a wide variety of neuronal insults in animal models, engendering enthusiasm that PC could be used to protect the brain clinically. Candidate clinical applications include cardiac and vascular surgery, after subarachnoid hemorrhage, and prior to conditions in which acute neuronal injury is anticipated. However, disappointments in clinical validation of multiple neuroprotectants suggest potential problems translating animal data into successful human therapies. Thus, despite strong promise of preclinical PC studies, caution should be maintained in translating these findings into clinical applications. The Stroke Therapy Academic Industry Roundtable (STAIR) working group and the National institute of Neurological Diseases and Stroke (NINDS) proposed working guidelines to improve the utility of preclinical studies that form the foundation of therapies for neurological disease. Here, we review the applicability of these consensus criteria to preconditioning studies and discuss additional considerations for PC studies. We propose that special attention should be paid to several areas, including 1) safety and dosage of PC treatments; 2) meticulously matching preclinical modeling to the human condition to be tested; and 3) timing of both the initiation and discontinuation of the PC stimulus relative to injury ictus.

Hyperbaric oxygen therapy in acute ischemic stroke: a review

Stroke, also known as cerebrovascular disease, is a common and serious neurological disease, which is also the fourth leading cause of death in the United States so far. Hyperbaric medicine, as an emerging interdisciplinary subject, has been applied in the treatment of cerebral vascular diseases since the 1960s. Now it is widely used to treat a variety of clinical disorders, especially hypoxia-induced disorders. However, owing to the complex mechanisms of hyperbaric oxygen (HBO) treatment, the therapeutic time window and the undefined dose as well as some common clinical side effects (such as middle ear barotrauma), the widespread promotion and application of HBO was hindered, slowing down the hyperbaric medicine development. In August 2013, the US Food and Drug Administration declared artery occlusion as one of the 13 specific indications for HBO therapy. This provides opportunities, to some extent, for the further development of hyperbaric medicine. Currently, the mechanisms of HBO therapy for ischemic stroke are still not very clear. This review focuses on the potential mechanisms of HBO therapy in acute ischemic stroke as well as the time window.

Repetitive long-term hyperbaric oxygen treatment (HBOT) administered after experimental traumatic brain injury in rats induces significant remyelination and a recovery of sensorimotor function

Cells in the central nervous system rely almost exclusively on aerobic metabolism. Oxygen deprivation, such as injury-associated ischemia, results in detrimental apoptotic and necrotic cell loss. There is evidence that repetitive hyperbaric oxygen therapy (HBOT) improves outcomes in traumatic brain-injured patients. However, there are no experimental studies investigating the mechanism of repetitive long-term HBOT treatment-associated protective effects. We have therefore analysed the effect of long-term repetitive HBOT treatment on brain trauma-associated cerebral modulations using the lateral fluid percussion model for rats. Trauma-associated neurological impairment regressed significantly in the group of HBO-treated animals within three weeks post trauma. Evaluation of somatosensory-evoked potentials indicated a possible remyelination of neurons in the injured hemisphere following HBOT. This presumption was confirmed by a pronounced increase in myelin basic protein isoforms, PLP expression as well as an increase in myelin following three weeks of repetitive HBO treatment. Our results indicate that protective long-term HBOT effects following brain injury is mediated by a pronounced remyelination in the ipsilateral injured cortex as substantiated by the associated recovery of sensorimotor function.

The medical use of oxygen: a time for critical reappraisal

Oxygen treatment has been a cornerstone of acute medical care for numerous pathological states. Initially, this was supported by the assumed need to avoid hypoxaemia and tissue hypoxia. Most acute treatment algorithms, therefore, recommended the liberal use of a high fraction of inspired oxygen, often without first confirming the presence of a hypoxic insult. However, recent physiological research has underlined the vasoconstrictor effects of hyperoxia on normal vasculature and, consequently, the risk of significant blood flow reduction to the at-risk tissue. Positive effects may be claimed simply by relief of an assumed local tissue hypoxia, such as in acute cardiovascular disease, brain ischaemia due to, for example, stroke or shock or carbon monoxide intoxication. However, in most situations, a generalized hypoxia is not the problem and a risk of negative hyperoxaemia-induced local vasoconstriction effects may instead be the reality. In preclinical studies, many important positive anti-inflammatory effects of both normobaric and hyperbaric oxygen have been repeatedly shown, often as surrogate end-points such as increases in gluthatione levels, reduced lipid peroxidation and neutrophil activation thus modifying ischaemia-reperfusion injury and also causing anti-apoptotic effects. However, in parallel, toxic effects of oxygen are also well known, including induced mucosal inflammation, pneumonitis and retrolental fibroplasia. Examining the available 'strong' clinical evidence, such as usually claimed for randomized controlled trials, few positive studies stand up to scrutiny and a number of trials have shown no effect or even been terminated early due to worse outcomes in the oxygen treatment arm. Recently, this has led to less aggressive approaches, even to not providing any supplemental oxygen, in several acute care settings, such as resuscitation of asphyxiated newborns, during acute myocardial infarction or after stroke or cardiac arrest. The safety of more advanced attempts to deliver increased oxygen levels to hypoxic or ischaemic tissues, such as with hyperbaric oxygen therapy, is therefore also being questioned. Here, we provide an overview of the present knowledge of the physiological effects of oxygen in relation to its therapeutic potential for different medical conditions, as well as considering the potential for harm. We conclude that the medical use of oxygen needs to be further examined in search of solid evidence of benefit in many of the current clinical settings in which it is routinely used.

A review of oxygen therapy in ischemic stroke

Neuroprotective drugs have so far failed clinical trials, at high cost, and intravenous tissue plasminogen activator (i.v. tPA) remains the only FDA-approved acute stroke therapy. Hyperoxia, acting via multiple direct and indirect mechanisms, may be a powerful neuroprotective strategy to salvage acutely ischemic brain tissue and extend the time window for acute stroke treatment. Of the available oxygen delivery methods, hyperbaric oxygen therapy (HBO) appears to be the most potent, while even normobaric oxygen therapy (NBO) may be effective if started promptly after stroke onset. HBO has so far failed to show efficacy in three clinical trials. The failure of these trials is probably attributable to factors such as delayed time to therapy, inadequate sample size and use of excessive chamber pressures. Previous trials did not assess long-term benefit in patients with tissue reperfusion. In this modern era of stroke thrombolysis and advanced neuroimaging, oxygen therapy may have renewed significance. If applied within the first few hours after stroke onset or in patients with imaging evidence of salvageable brain tissue, oxygen therapy could be used to 'buy time' for the administration of thrombolytic or neuroprotective drugs. This article reviews the history and current rationale for using oxygen therapy in stroke, the mechanisms of action of HBO and the results of animal and human studies of hyperoxia in cerebrovascular diseases.

Long course hyperbaric oxygen stimulates neurogenesis and attenuates inflammation after ischemic stroke

Several studies have provided evidence with regard to the neuroprotection benefits of hyperbaric oxygen (HBO) therapy in cases of stroke, and HBO also promotes bone marrow stem cells (BMSCs) proliferation and mobilization. This study investigates the influence of HBO therapy on the migration of BMSCs, neurogenesis, gliosis, and inflammation after stroke. Rats that sustained transient middle cerebral artery occlusion (MCAO) were treated with HBO three weeks or two days. The results were examined using a behavior test (modified neurological severity score, mNSS) and immunostaining to evaluate the effects of HBO therapy on migration of BMSCs, neurogenesis, and gliosis, and expression of neurotrophic factors was also evaluated. There was a lower mNSS score in the three-week HBO group when compared with the two-day HBO group. Mobilization of BMSCs to an ischemic area was more improved in long course HBO treatments, suggesting the duration of therapy is crucial for promoting the homing of BMSCs to ischemic brain by HBO therapies. HBO also can stimulate expression of trophic factors and improve neurogenesis and gliosis. These effects may help in neuronal repair after ischemic stroke, and increasing the course of HBO therapy might enhance therapeutic effects on ischemic stroke.

All-trans retinoic acid rescues memory deficits and neuropathological changes in mouse model of streptozotocin-induced dementia of Alzheimer's type

Recent studies have revealed that aberrant vitamin A signaling may lead to memory deficits in rodents. Present study investigates the potential of all-trans-retinoic acid (ATRA) an agonist at retinoid acid family of receptors, in cognitive dysfunctions associated with experimental dementia. Streptozotocin (STZ) [3 mg/kg, intracerebroventricularly (i.c.v)] was administered on alternate days (day 1 and day 3) to induce dementia in Swiss albino mice. STZ mice were administered ATRA (10 mg/kg; 20 mg/kg, p.o.) for a total of 19 days following second i.c.v injection of STZ [day 4 to day 22]. Morris water maze (MWM) test was performed on days 19, 20, 21, 22 and 23 to assess learning and memory of the animals. Following MWM test, the animals were sacrificed for biochemical and histopathological studies. Extent of oxidative stress was measured by estimating the levels of brain reduced glutathione (GSH) and thiobarbituric acid reactive species (TBARS). Brain acetylcholinestrase (AChE) activity and serum cholesterol levels were also estimated. The brain level of myeloperoxidase (MPO) was measured as a marker of inflammation. STZ produced a marked decline in MWM performance of the animals, reflecting impairment of learning and memory. STZ treated mice showed marked accentuation of AChE activity, TBARS and MPO levels along with fall in GSH level. Further the stained micrographs of STZ-treated mice indicated pathological changes, severe neutrophilic infiltration and amyloid deposition. ATRA treatment significantly attenuated STZ-induced memory deficits, biochemical and histopathological alterations. The findings demonstrate that the memory restorative ability of ATRA may be attributed to its anti-cholinesterase, anti-oxidative and anti-inflammatory potential.

Role of hyperbaric oxygen therapy in severe head injury in children

Aim:

A brain injury results in a temporary or permanent impairment of cognitive, emotional, and/or physical function. Predicting the outcome of pediatric brain injury is difficult. Prognostic instruments are not precise enough to reliably predict individual patient's mortality and long-term functional status. The purpose of this article is to provide a guide to the strengths and limitations of the use of hyperbaric oxygen therapy (HBOT) in treating pediatric patients with severe brain injury.

Materials and Methods:

We studied total 56 patients of head injury. Out of them 28 received HBOT. Only cases with severe head injury [Glasgow Coma Scale (GCS) < 8] with no other associated injury were included in the study group. After an initial period of resuscitation and conservative management (10–12 days), all were subjected to three sessions of HBOT at 1-week interval. This study group was compared with a control group of similar severity of head injury (GCS < 8).

Results:

The study and control groups were compared in terms of duration of hospitalization, GCS, disability reduction,and social behavior. Patients who received HBOT were significantly better than the control group on all the parameters with decreased hospital stay, better GCS, and drastic reduction in disability.

Conclusion:

In children with traumatic brain injury, the addition of HBOT significantly improved outcome and quality of life and reduced the risk of complications.

Hyperbaric oxygen and hyperbaric air treatment result in comparable neuronal death reduction and improved behavioral outcome after transient forebrain ischemia in the gerbil

Anoxic brain injury resulting from cardiac arrest is responsible for approximately two-thirds of deaths. Recent evidence suggests that increased oxygen delivered to the brain after cardiac arrest may be an important factor in preventing neuronal damage, resulting in an interest in hyperbaric oxygen (HBO) therapy. Interestingly, increased oxygen supply may be also reached by application of normobaric oxygen (NBO) or hyperbaric air (HBA). However, previous research also showed that the beneficial effect of hyperbaric treatment may not directly result from increased oxygen supply, leading to the conclusion that the mechanism of hyperbaric prevention of brain damage is not well understood. The aim of our study was to compare the effects of HBO, HBA and NBO treatment on gerbil brain condition after transient forebrain ischemia, serving as a model of cardiac arrest. Thereby, we investigated the effects of repetitive HBO, HBA and NBO treatment on hippocampal CA1 neuronal survival, brain temperature and gerbils behavior (the nest building), depending on the time of initiation of the therapy (1, 3 and 6 h after ischemia). HBO and HBA applied 1, 3 and 6 h after ischemia significantly increased neuronal survival and behavioral performance and abolished the ischemia-evoked brain temperature increase. NBO treatment was most effective when applied 1 h after ischemia; later application had a weak or no protective effect. The results show that HBO and HBA applied between 1 and 6 h after ischemia prevent ischemia-evoked neuronal damage, which may be due to the inhibition of brain temperature increase, as a result of the applied rise in ambient pressure, and just not due to the oxygen per se. This perspective is supported by the finding that NBO treatment was less effective than HBO or HBA therapy. The results presented in this paper may pave the way for future experimental studies dealing with pressure and temperature regulation.

Therapeutic window of taurine against experimental stroke in rats

The dose-dependent protection of taurine against experimental stroke has been demonstrated previously. The objective of this study was to investigate the therapeutic window of taurine against experimental stroke, and the effects of delayed administration of taurine on inflammatory reaction in a rat model of stroke. Rats received 2-h ischemia by intraluminal filament, and then reperfused. Taurine (50 mg/kg) was administered intravenously 4 h, 8 h, 10 h, or 12 h after ischemia. The neurologic scores and the infarct volumes were evaluated 24 h after ischemia. Then, the effect of administration of taurine at 8 h after ischemia on the neutrophil infiltration in ischemic region was determined. Treatment with taurine 4 h or 8 h after ischemia significantly improved the neurologic function, and decreased the infarct volumes 24 h after ischemia. However, administration of taurine at 10 h or 12 h after ischemia had no significant neuroprotection. Further, taurine administered at 8 h after ischemia markedly reduced myeloperoxidase activity and attenuated neutrophil infiltration in ischemic region. Our data suggest that the therapeutic window of taurine against experimental stroke is of at least 8 h, and suppressing the neutrophil infiltration may be one of the mechanisms of delayed administration of taurine against experimental stroke.

Attenuating inflammation but stimulating both angiogenesis and neurogenesis using hyperbaric oxygen in rats with traumatic brain injury

BACKGROUND

Inflammation, angiogenesis, neurogenesis, and gliosis are involved in traumatic brain injury (TBI). Several studies provide evidence supporting the neuroprotective effect of hyperbaric oxygen (HBO2) therapy in TBI. The aim of this study was to ascertain whether inflammation, angiogenesis, neurogenesis, and gliosis during TBI are affected by HBO2 therapy.

METHODS

Rats were randomly divided into three groups: TBI + NBA (normobaric air: 21% O2 at 1 absolute atmospheres), TBI + HBO2, and Sham operation + NBA. TBI + HBO2 rats received 100% O2 at 2.0 absolute atmospheres for 1 hr/d for three consecutive days. Behavioral tests and biochemical and histologic evaluations were done 4 days after TBI onset.

RESULTS

TBI + NBA rats displayed: (1) motor and cognitive dysfunction; (2) cerebral infarction and apoptosis; (3) activated inflammation (evidenced by increased brain myeloperoxidase activity and higher serum levels of tumor necrosis factor-α); (4) neuronal loss (evidenced by fewer NeuN-positive cells); and (5) gliosis (evidenced by more glial fibrillary protein-positive cells). In TBI + HBO2 rats, HBO2 therapy significantly reduced TBI-induced motor and cognitive dysfunction, cerebral infarction and apoptosis, activated inflammation, neuronal loss, and gliosis. In addition, HBO2 therapy stimulated angiogenesis (evidenced by more bromodeoxyuridine-positive endothelial and vascular endothelial growth factor-positive cells), neurogenesis (evidenced by more bromodeoxyuridine-NeuN double-positive and glial cells-derived neurotrophic factor-positive cells), and overproduction of interleukin-10 (an anti-inflammatory cytokine).

CONCLUSIONS

Collectively, these results suggest that HBO2 therapy may improve outcomes of TBI in rats by inhibiting activated inflammation and gliosis while stimulating both angiogenesis and neurogenesis in the early stage.

Spatio-temporal course of macrophage-like cell accumulation after experimental embolic stroke depending on treatment with tissue plasminogen activator and its combination with hyperbaric oxygenation

Inflammation following ischaemic stroke attracts high priority in current research, particularly using human-like models and long-term observation periods considering translational aspects. The present study aimed on the spatio-temporal course of macrophage-like cell accumulation after experimental thromboembolic stroke and addressed microglial and astroglial reactions in the ischaemic border zone. Further, effects of tissue plasminogen activator (tPA) as currently best treatment for stroke and the potentially neuroprotective co-administration of hyperbaric oxygen (HBO) were investigated. Rats underwent middle cerebral artery occlusion and were assigned to control, tPA or tPA+HBO. Twenty-four hours, 7, 14 and 28 days were determined as observation time points. The accumulation of macrophage-like cells was semiquantitatively assessed by CD68 staining in the ischaemic area and ischaemic border zone, and linked to the clinical course. CD11b, ionized calcium binding adaptor molecule 1 (Iba), glial fibrillary acidic protein (GFAP) and Neuronal Nuclei (NeuN) were applied to reveal delayed glial and neuronal alterations. In all groups, the accumulation of macrophage-like cells increased distinctly from 24 hours to 7 days post ischaemia. tPA+HBO tended to decrease macrophage-like cell accumulation at day 14 and 28. Overall, a trend towards an association of increased accumulation and pronounced reduction of the neurological deficit was found. Concerning delayed inflammatory reactions, an activation of microglia and astrocytes with co-occurring neuronal loss was observed on day 28. Thereby, astrogliosis was found circularly in contrast to microglial activation directly in the ischaemic area. This study supports previous data on long-lasting inflammatory processes following experimental stroke, and additionally provides region-specific details on glial reactions. The tendency towards a decreasing macrophage-like cell accumulation after tPA+HBO needs to be discussed critically since neuroprotective properties were recently ascribed to long-term inflammatory processes.

The Anti-Inflammatory Effect of Paeoniflorin on Cerebral Infarction Induced by Ischemia-Reperfusion Injury in Sprague-Dawley Rats

Paeoniflorin, a component in Paeonia lactiflora Pall, inhibits nuclear factor-κB expression in chronic hypoperfusion rat and has anti-inflammatory properties. Therefore, the aim of the present study was to investigate the effect of paeoniflorin on cerebral infarct, and the involvement of anti-inflammation. We established an animal model of cerebral infarct by occluding both the common carotid arteries and the right middle cerebral artery for 90 min, followed by reperfusion of 24 hours. The ratios of cerebral infarction area to total brain area, and neuro-deficit score were used as an index to observe the effects of paeoniflorin on cerebral infarct. ED1 (mouse anti rat CD68), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), intercellular adhesion molecular-1 (ICAM-1), myeloperoxidase (MPO) immunostaining and apoptotic cells in the cerebral infarction region also were studied. The results indicated that both pre-treatment and post-treatment with paeoniflorin reduced the ratio of cerebral infarction area; pre-treatment with paeoniflorin also reduced the neurological deficit score. The counts of ED1, IL-1β, TNF-α, ICAM-1 of microvessels and MPO immunoreactive cells and apoptotic cells were increased in the cerebral infarction region; however, these increases were reduced by Paeoniflorin pre-treatment.

In conclusion, Paeoniflorin reduced cerebral infarct and neurological deficit in ischemia-reperfusion injured rats, suggesting that paeoniflorin may have a similar effect in humans and might be a suitable treatment for stroke. Paeoniflorin reduced cerebral infarct, at least in part, involves the anti-inflammatory properties.

Hyperbaric oxygen therapy in a mouse model of implant-associated osteomyelitis

Implant associated osteomyelitis (OM) is difficult to treat with antibiotics, and outcomes remain poor. Some reports suggest that hyperbaric oxygen treatment is a safe and effective means of treating OM. We tested this hypothesis in a murine model. Clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Klebsiella pneumoniae were used. The mice were infected with each of the three pathogens, treated with 100% oxygen at high pressure, hyperbaric oxygen (HBO), and monitored for the ability of HBO to prevent and/or clear the OM infection. Assessments included bacterial burden of the tibias and lesion scores, as well as receptor activator of NF-κB ligand (RANKL) and myeloperoxidase (MPO) concentrations. HBO resulted in more severe lesion scores and higher RANKL and MPO concentrations for MRSA. A significant positive correlation was found between RANKL concentration and lesion score. No significant difference was found with HBO in P. aeruginosa infections and K. pneumoniae seems to either not infect bone well or get cleared before establishing an infection. The model is useful for studying OM infections caused by MRSA and P. aeruginosa, but HBO does not appear to be an efficacious treatment of an implant-associated OM infection.

Normobaric oxygen therapy in acute ischemic stroke: A pilot study in Indian patients

Purpose:

Clinical and radiological assessment of effects of normobaric high-flow oxygen therapy in patients with acute ischemic stroke (AIS).

Materials and Methods:

Patients with anterior circulation ischemic strokes presenting within 12 h of onset, ineligible for intravenous thrombolysis, an National Institute of Health Stroke Scale (NIHSS) score of >4, a mean transit time (MTT) lesion larger than diffusion-weighted image (DWI) (perfusiondiffusion mismatch), and an evidence of cortical hypoperfusion on magnetic resonance imaging (MRI) were included into the trial. Active chronic obstructive pulmonary disease (COPD), requirement of >3/L min oxygen delivery to maintain SaO2 > 95%, rapidly improving neurological deficits, pregnancy, contraindications to MRI, or unstable medical conditions were excluded. The experimental group received humidified oxygen at flow rates of 10 L/min for 12 h. The NIHSS, modified Rankin Score (mRS), Barthel Index (BI) were measured at 0, 1, 7 day of admission and at 3 months follow-up. MRI with DWI/PWI was performed at admission, 24 h later and at 3 months follow-up.

Results:

Of 40 patients (mean age = 55.8 years ± 13.2) (range, 26–82), 20 patients were randomized to normobaric oxygen (NBO). The mean NIHSS in NBO and control groups were 14.25 and 12.7 at admission which decreased to 11.6 and 9.5 on the seventh day, and 9.4 and 9.05 at 3 months, respectively. The mean mRS (3.7/3.7) and BI (58.2/53.9) in NBO and control groups improved to 2/2.2 and 73.05/73.8 at the end of 3 months, respectively.

Conclusions:

NBO did not improve the clinical scores of stroke outcome in Indian patients with AIS.

Anti-inflammatory mechanism of taurine against ischemic stroke is related to down-regulation of PARP and NF-κB

Taurine is reported to reduce tissue damage induced by inflammation and to protect the brain against experimental stroke. The objective of this study was to investigate whether taurine reduced ischemic brain damage through suppressing inflammation related to poly (ADP-ribose) polymerase (PARP) and nuclear factor-kappaB (NF-κB) in a rat model of stroke. Rats received 2 h ischemia by intraluminal filament and were then reperfused. Taurine (50 mg/kg) was administered intravenously 1 h after ischemia. Treatment with taurine markedly reduced neurological deficits, lessened brain swelling, attenuated cell death, and decreased the infarct volume 72 h after ischemia. Our data showed the up-regulation of PARP and NF-κB p65 in cytosolic fractions in the core and nuclear fractions in the penumbra and core, and the increases in the nuclear poly (ADP-ribose) levels and the decreases in the intracellular NAD+ levels in the penumbra and core at 22 h of reperfusion; these changes were reversed by taurine. Moreover, taurine significantly reduced the levels of tumor necrosis factor-α, interleukin-1β, inducible nitric oxide synthase, and intracellular adhesion molecule-1, lessened the activities of myeloperoxidase and attenuated the infiltration of neutrophils in the penumbra and core at 22 h of reperfusion. These data demonstrate that suppressing the inflammatory reaction related to PARP and NF-κB-driven expression of inflammatory mediators may be one mechanism of taurine against ischemic stroke.

Use of normobaric and hyperbaric oxygen in acute focal cerebral ischemia - a preclinical and clinical review

High socioeconomic burden is attributed to acute ischemic stroke, but treatment strategies are still limited. Normobaric (NBO) and hyperbaric oxygen therapy (HBO) were frequently investigated in preclinical studies following acute focal cerebral ischemia with predominantly beneficial effects in different outcome measurements. Best results were achieved in transient cerebral ischemia, starting HBO early after artery occlusion, and by using relatively high pressures. On molecular level, oxygen application leads to blood-brain barrier stabilization, reduction of excitotoxic metabolites, and inhibition of inflammatory processes. Therefore, NBO and HBO appear excessively hopeful in salvaging impaired brain cells during ischemic stroke. However, harmful effects have been noted contributing to damaging properties, for example, vasoconstriction and free oxygen radicals. In the clinical setting, NBO provided positive results in a single clinical trial, but HBO failed to show efficacy in three randomized trials. To date, the translation of numerous evidentiary experimental results into clinical implementation remains open. Recently, oxygen became interesting as an additional therapy to neuroprotective or recanalization drugs to combine positive effects. Further preclinical research is needed exploring interactions between NBO, HBO, and key factors with multiphasic roles in acute damaging and delayed inflammatory processes after cerebral ischemia, for example, matrix-metalloproteinases and hypoxia-inducible factor-1α.

Aspectos morfológicos e funcionais dos autoimplantes esplênicos em ratos tratados com oxigenio hiperbárico

OBJETIVO: Estudar aspectos morfológicos e funcionais dos autoimplantes esplênicos de ratos submetidos ou não à oxigenioterapia hiperbárica (OHB). MÉTODOS: Foram estudados em dois períodos distintos 105 ratos Wistar. No período mediato (n= 56) os animais foram avaliados até o 11º dia de pós-operatório, e no período tardio (n= 49), até o 70º dia. Em cada período os ratos foram distribuídos nos grupos: A- Simulação, B- Autoimplante esplênico, tratados com oxigênio hiperbárico ou não. Nos animais do Grupo A realizou-se apenas manipulação do baço. Nos animais do Grupo B realizou-se esplenectomia total e a seguir quatro fragmentos do baço foram implantados no grande omento. Em todos os animais foram dosados os lípides e imunoglobulinas e contadas as plaquetas e os corpúsculos de Howell-Jolly no pré-operatório e no 11º ou 70º dia de pós-operatório. O baço dos animais do Grupo A e os autoimplantes dos animais do Grupo B foram retirados e enviados para avaliação morfológica. RESULTADOS: No grupo B11nt houve aumento do colesterol total, LDL-colesterol, VLDL-colesterol e triglicérides. No grupo B70nt houve aumento do colesterol total e LDL-colesterol. Nos grupos tratados não houve alterações lipídicas. A IgM caiu nos grupos B e não alterou nos grupos A. Os corpúsculos de Howell - Jolly foram menos freqüentes nos grupos Bt que nos grupos Bnt. As plaquetas aumentaram nos grupos B11t e B11nt e não se alteraram nos demais grupos. A viabilidade microscópica dos grupos Bt foi melhor que a dos grupos Bnt. CONCLUSÃO: Os autoimplantes esplênicos dos animais tratados com OHB apresentaram melhor função e viabilidade do que os autoimplantes dos animais não tratados.

Neutralization of interleukin-1beta modifies the inflammatory response and improves histological and cognitive outcome following traumatic brain injury in mice

Interleukin-1beta (IL-1beta) may play a central role in the inflammatory response following traumatic brain injury (TBI). We subjected 91 mice to controlled cortical impact (CCI) brain injury or sham injury. Beginning 5 min post-injury, the IL-1beta neutralizing antibody IgG2a/k (1.5 microg/mL) or control antibody was infused at a rate of 0.25 microL/h into the contralateral ventricle for up to 14 days using osmotic minipumps. Neutrophil and T-cell infiltration and microglial activation was evaluated at days 1-7 post-injury. Cognition was assessed using Morris water maze, and motor function using rotarod and cylinder tests. Lesion volume and hemispheric tissue loss were evaluated at 18 days post-injury. Using this treatment strategy, cortical and hippocampal tissue levels of IgG2a/k reached 50 ng/mL, sufficient to effectively inhibit IL-1betain vitro. IL-1beta neutralization attenuated the CCI-induced cortical and hippocampal microglial activation (P < 0.05 at post-injury days 3 and 7), and cortical infiltration of neutrophils (P < 0.05 at post-injury day 7). There was only a minimal cortical infiltration of activated T-cells, attenuated by IL-1beta neutralization (P < 0.05 at post-injury day 7). CCI induced a significant deficit in neurological motor and cognitive function, and caused a loss of hemispheric tissue (P < 0.05). In brain-injured animals, IL-1beta neutralizing treatment resulted in reduced lesion volume, hemispheric tissue loss and attenuated cognitive deficits (P < 0.05) without influencing neurological motor function. Our results indicate that IL-1beta is a central component in the post-injury inflammatory response that, in view of the observed positive neuroprotective and cognitive effects, may be a suitable pharmacological target for the treatment of TBI.

Hyperbaric oxygen therapy and cerebral ischemia: neuroprotective mechanisms

INTRODUCTION

Numerous studies have demonstrated a protective effect of hyperbaric oxygen therapy in experimental ischemic brain injury, and many physiological and molecular mechanisms of hyperbaric oxygen therapy-related neuroprotection have been identified.

METHODS

Review of articles pertaining to hyperbaric oxygen therapy and cerebral ischemia in the National Library of Medicine and National Institutes of Health database, emphasizing mechanisms of hyperbaric oxygen therapy-related neuroprotection.

RESULTS

Hyperbaric oxygen therapy has been shown to ameliorate brain injury in a variety of animal models including focal cerebral ischemia, global cerebral ischemia, neonatal hypoxia-ischemia and subarachnoid hemorrhage. Small human trials of hyperbaric oxygen therapy in focal ischemia have not shown benefit, although one trial of hyperbaric oxygen therapy before cardiopulmonary bypass demonstrated improved neuropsychological and inflammatory outcomes with hyperbaric oxygen therapy. Hyperbaric oxygen therapy is associated with improved cerebral oxygenation, reduced blood-brain barrier breakdown, decreased inflammation, reduced cerebral edema, decreased intracranial pressure, reduced oxidative burden, reduced metabolic derangement, decreased apoptotic cell death and increased neural regeneration.

CONCLUSION

On a molecular level, hyperbaric oxygen therapy leads to activation of ion channels, inhibition of hypoxia inducible factor-1alpha, up-regulation of Bcl-2, inhibition of MMP-9, decreased cyclooxygenase-2 activity, decreased myeloperoxidase activity, up-regulation of superoxide dismutase and inhibition of Nogo-A (an endogenous growth-inhibitory factor). Ongoing research will continue to describe the mechanisms of hyperbaric oxygen therapy-related neuroprotection, and possibly expand hyperbaric oxygen therapy use clinically.

Hyperbaric treatment for children with autism: a multicenter, randomized, double-blind, controlled trial

Background

Several uncontrolled studies of hyperbaric treatment in children with autism have reported clinical improvements; however, this treatment has not been evaluated to date with a controlled study. We performed a multicenter, randomized, double-blind, controlled trial to assess the efficacy of hyperbaric treatment in children with autism.

Methods

62 children with autism recruited from 6 centers, ages 2–7 years (mean 4.92 ± 1.21), were randomly assigned to 40 hourly treatments of either hyperbaric treatment at 1.3 atmosphere (atm) and 24% oxygen ("treatment group", n = 33) or slightly pressurized room air at 1.03 atm and 21% oxygen ("control group", n = 29). Outcome measures included Clinical Global Impression (CGI) scale, Aberrant Behavior Checklist (ABC), and Autism Treatment Evaluation Checklist (ATEC).

Results

After 40 sessions, mean physician CGI scores significantly improved in the treatment group compared to controls in overall functioning (p = 0.0008), receptive language (p < 0.0001), social interaction (p = 0.0473), and eye contact (p = 0.0102); 9/30 children (30%) in the treatment group were rated as "very much improved" or "much improved" compared to 2/26 (8%) of controls (p = 0.0471); 24/30 (80%) in the treatment group improved compared to 10/26 (38%) of controls (p = 0.0024). Mean parental CGI scores significantly improved in the treatment group compared to controls in overall functioning (p = 0.0336), receptive language (p = 0.0168), and eye contact (p = 0.0322). On the ABC, significant improvements were observed in the treatment group in total score, irritability, stereotypy, hyperactivity, and speech (p < 0.03 for each), but not in the control group. In the treatment group compared to the control group, mean changes on the ABC total score and subscales were similar except a greater number of children improved in irritability (p = 0.0311). On the ATEC, sensory/cognitive awareness significantly improved (p = 0.0367) in the treatment group compared to the control group. Post-hoc analysis indicated that children over age 5 and children with lower initial autism severity had the most robust improvements. Hyperbaric treatment was safe and well-tolerated.

Conclusion

Children with autism who received hyperbaric treatment at 1.3 atm and 24% oxygen for 40 hourly sessions had significant improvements in overall functioning, receptive language, social interaction, eye contact, and sensory/cognitive awareness compared to children who received slightly pressurized room air.

Trial Registration

clinicaltrials.gov NCT00335790

Hyperbaric oxygen preconditioning protects against traumatic brain injury at high altitude

BACKGROUND

Recent studies have shown that preconditioning with hyperbaric oxygen (HBO) can reduce ischemic and hemorrhagic brain injury. We investigated effects of HBO preconditioning on traumatic brain injury (TBI) at high altitude and examined the role of matrix metalloproteinase-9 (MMP-9) in such protection.

METHODS

Rats were randomly divided into 3 groups: HBO preconditioning group (HBOP; n = 13), high-altitude group (HA; n = 13), and high-altitude sham operation group (HASO; n = 13). All groups were subjected to head trauma by weight-drop device, except for HASO group. HBOP rats received 5 sessions of HBO preconditioning (2.5 ATA, 100% oxygen, 1 h daily) and then were kept in hypobaric chamber at 0.6 ATA (to simulate pressure at 4000m altitude) for 3 days before operation. HA rats received control pretreatment (1 ATA, room air, 1 h daily), then followed the same procedures as HBOP group. HASO rats were subjected to skull opening only without brain injury. Twenty-four hours after TBI, 7 rats from each group were examined for neurological function and brain water content; 6 rats from each group were killed for analysis by H&E staining and immunohistochemistry.

RESULTS

Neurological outcome in HBOP group (0.71 +/- 0.49) was better than HA group (1.57 +/- 0.53; p < 0.05). Preconditioning with HBO significantly reduced percentage of brain water content (86.24 +/- 0.52 vs. 84.60 +/- 0.37; p < 0.01). Brain morphology and structure seen by light microscopy was diminished in HA group, while fewer pathological injuries occurred in HBOP group. Compared to HA group, pretreatment with HBO significantly reduced the number of MMP-9-positive cells (92.25 +/- 8.85 vs. 74.42 +/- 6.27; p < 0.01).

CONCLUSIONS

HBO preconditioning attenuates TBI in rats at high altitude. Decline in MMP-9 expression may contribute to HBO preconditioning-induced protection of brain tissue against TBI.

Oxygen therapy in stroke: past, present, and future

Oxygen is frequently administered to patients with suspected stroke. However, the role of oxygen therapy in ischemic stroke remains controversial in light of the failure of three clinical trials of hyperbaric oxygen therapy to show efficacy, and the fear of exacerbating oxygen free radical injury. The previous trials had several shortcomings, perhaps because they were designed on basis of anecdotal case reports and little preclinical data. Most animal studies concerning oxygen therapy in stroke have been conducted over the last 6 years. Emerging data suggests that hyperbaric and even normobaric oxygen therapy can be effective if used appropriately, and raises the tantalizing possibility that hyperoxia can be used to extend the narrow therapeutic time window for stroke thrombolysis. This article reviews the history, rationale, mechanisms of action and adverse effects of hyperoxia, the key results of previous hyperoxia studies, and the potential role of oxygen therapy in contemporary stroke treatment.

Microglia cells protect neurons by direct engulfment of invading neutrophil granulocytes: a new mechanism of CNS immune privilege

Microglial cells maintain the immunological integrity of the healthy brain and can exert protection from traumatic injury. During ischemic tissue damage such as stroke, peripheral immune cells acutely infiltrate the brain and may exacerbate neurodegeneration. Whether and how microglia can protect from this insult is unknown. Polymorphonuclear neutrophils (PMNs) are a prominent immunologic infiltrate of ischemic lesions in vivo. Here, we show in organotypic brain slices that externally applied invading PMNs massively enhance ischemic neurotoxicity. This, however, is counteracted by additional application of microglia. Time-lapse imaging shows that microglia exert protection by rapid engulfment of apoptotic, but, strikingly, also viable, motile PMNs in cell culture and within brain slices. PMN engulfment is mediated by integrin- and lectin-based recognition. Interference with this process using RGDS peptides and N-acetyl-glucosamine blocks engulfment of PMNs and completely abrogates the neuroprotective function of microglia. Thus, engulfment of invading PMNs by microglia may represent an entirely new mechanism of CNS immune privilege.

Hyperbaric oxygen-induced attenuation of hemorrhagic transformation after experimental focal transient cerebral ischemia

BACKGROUND AND PURPOSE

An increased risk of hemorrhagic transformation is a major factor limiting the use of tissue plasminogen activator for stroke. Increased hemorrhagic transformation is also found in animals undergoing transient focal cerebral ischemia with hyperglycemia; this study examined whether hyperbaric oxygen (HBO) could reduce such hemorrhagic transformation in a rat model.

METHODS

Rats received an injection of 50% glucose (6 mL/kg intraperitoneally) and had a middle cerebral artery occlusion 10 minutes later. Rats were treated with HBO (3 ATA for 1 hour) 30 minutes after middle cerebral artery occlusion. Control rats received normobaric room air. Rats underwent reperfusion 2 hours after middle cerebral artery occlusion. Blood-brain barrier permeability (Evans blue), hemorrhagic transformation (hemoglobin content), brain edema, infarct volume, and mortality were measured.

RESULTS

HBO treatment reduced Evans blue leakage in the ipsilateral hemisphere (28.4+/-3.5 versus 71.8+/-13.1 microg/g in control group, P<0.01) 2 hours after reperfusion and hemorrhagic transformation (0.13+/-0.13 versus 0.31+/-0.28 mg hemoglobin in the control group, P<0.05) 22 hours later. Mortality was less in the HBO group (4% versus 27% in controls, P<0.05). Mean infarct volume and swelling in the caudate were also less in HBO-treated rats (P<0.05), but HBO failed to reduce brain water content in the ipsilateral hemisphere (P>0.05).

CONCLUSIONS

Early intraischemic HBO treatment reduces the blood-brain barrier disruption, hemorrhagic transformation, and mortality after focal cerebral ischemia suggesting that HBO could be used to reduce hemorrhagic conversion in patients with stroke.