[Protective effect of Apelin-13 on focal cerebral ischemia-reperfusion injury in rats]

OBJECTIVE

To investigate the protective effect of Apelin-13 on focal cerebral ischemia-reperfusion injury in rats.

METHODS

Focal transient cerebral ischemia-reperfusion injury was induced in male SD rats using modified suture occlusion technique. The rats were randomly divided into 5 groups: Sham group, Model group, Apelin-low dose (A) group, Apelin-middle dose (B) group and Apelin-high dose (C) group. Apelin-13 was injected into lateral cerebral ventricle, and the neurological function score, brain edema, infarct volume, apoptosis, malondialdehyde (MDA), superoxide dismutase (SOD) and extracellular regulated kinase1/2 (ERK1/2) protein were measured.

RESULTS

Neurological function scores, percentage of brain water content, infarct volumes and TUNEL-positive cells in B and C groups were lower than those in Model group (P<0.05). The level of MDA in the tissue bomogenate of brain tissue in the surrounding area of ischemia of B and C groups was lower than that of Model group, while the activity of SOD was higher (P<0.05). There was no significant difference in ERK1/2 protein expression among the groups (P>0.05). P-ERK1/2 increased in Model group and A, B, and C groups compared with Sham group (P<0.05), and that of A, B, and C group was higher than that of Model group (P<0.05).

CONCLUSION

Apelin-13 may play an important role by inhibiting oxidative stress to protect against focal cerebral ischemia-reperfusion injury; ERK1/2 signaling pathway may be involved in the protective mechanism of Apelin-13.

[Influenza-Associated Encephalopathy]

Influenza-associated encephalopathy is a syndrome that chiefly manifests consciousness disturbance provoked by influenza. It is defined pathologically as acute neurological dysfunction that results from non-inflammatory brain edema. The clinical picture is so diverse that many clinical subtypes and multiple pathologies have been proposed to date. Influenza-associated encephalopathy is diagnosed and treated according to the disease guideline in Japan, which has improved the outcome of influenza-associated encephalopathy. Although influenza-associated encephalopathy had been regarded as a childhood disease in Japan, adult cases and those in the US and Europe have been reported since the 2009 pandemic. Therefore, influenza-associated encephalopathy has been spotlighted.

Lesson of the month 1: A review of a diving emergency

Physicians should consider barotrauma and decompression illness (DCI) in any patient presenting after a recent scuba dive, even apparently shallow dives. If and when DCI is suspected, clinicians should act without delay to transfer the patient to a recompression facility, even if diagnostic certainty has not been attained. We present a case of hyperbaric injury in an asthmatic woman who had an atypical presentation in view of the depth of dive.

[Mountain sickness]

Mountaineering brings many health risks, one of which is mountain sickness. Its mildest form - acute mountain sickness - is mainly characterized by subjective symptoms (headache, loss of appetite, insomnia, weakness, nausea and rarely also vomiting). Advanced and life-threatening forms are characterized by tissue edema - cerebral or pulmonary high altitude edema. The common denominator of these acute forms is the low oxygen tension leading to hypoxemia and tissue ischemia. Sum of maladaptive or adaptive processes can modify the clinical picture. Underlying mechanisms of the chronic forms of pulmonary disease are the adaptation processes - pulmonary hypertension and polycythemia leading to heart failure.The only causal therapeutic intervention is to restore adequate oxygen tension, descend to lower altitudes or oxygen therapy. Pharmacotherapy has only a supportive effect. The prophylaxis includes stimulation of the respiratory center by carbonic anhydrase inhibitors (acetazolamide) antiedematous treatment with glucocorticoids (dexamethasone), increase lymphatic drainage of the lungs and brain by β2-agonists (salmeterol) or mitigation of pulmonary hypertension by calcium channel blockers or phosphodiesterase-5 inhibitors (sildenafil or tadalafil).

Linear accelerator stereotactic radiosurgery for trigeminal neuralgia

BACKGROUND

Stereotactic radiosurgery is accepted as an alternative for patients with refractory trigeminal neuralgia, but existing evidence is fundamentally based on the Gamma Knife, which is a specific device for intracranial neurosurgery, available in few facilities. Over the last decade it has been shown that the use of linear accelerators can achieve similar diagnostic accuracy and equivalent dose distribution.

OBJECTIVES

To assess the effectiveness and safety of linear-accelerator stereotactic radiosurgery for the treatment of patients with refractory trigeminal neuralgia.

METHODS

We carried out a systematic search of the literature in the main electronic databases (PubMed, Embase, ISI Web of Knowledge, Cochrane, Biomed Central, IBECS, IME, CRD) and reviewed grey literature. All original studies on the subject published in Spanish, French, English, and Portuguese were eligible for inclusion. The selection and critical assessment was carried out by 2 independent reviewers based on pre-defined criteria. In view of the impossibility of carrying out a pooled analysis, data were analyzed in a qualitative way.

RESULTS

Eleven case series were included. In these, satisfactory pain relief (BIN I-IIIb or reduction in pain = 50) was achieved in 75% to 95.7% of the patients treated. The mean time to relief from pain ranged from 8.5 days to 3.8 months. The percentage of patients who presented with recurrences after one year of follow-up ranged from 5% to 28.8%. Facial swelling or hypoesthesia, mostly of a mild-moderate grade appeared in 7.5% - 51.9% of the patients. Complete anaesthesia dolorosa was registered in only study (5.3%). Cases of hearing loss (2.5%), brainstem edema (5.8%), and neurotrophic keratoplasty (3.5%) were also isolated.

CONCLUSIONS

The results suggest that stereotactic radiosurgery with linear accelerators could constitute an effective and safe therapeutic alternative for drug-resistant trigeminal neuralgia. However, existing studies leave important doubts as to optimal treatment doses or the therapeutic target, long-term recurrence, and do not help identify which subgroups of patients could most benefit from this technique.

LIMITATIONS

Paucity of literature and clear lack of clarification for clinical utilization of this technique.

[Cyberknife radiosurgery for cerebral arteriovenous malformations: outlining of the radiosurgical target and obliteration]

OBJECTIVE

To explore the therapeutic outcomes of cyberknife for patients with arteriovenous malformations (AVM) and outline the content of AVM targets.

METHODS

Between January 2008 and October 2011, 51 patients underwent cyberknife radiosurgery for cerebral AVMs. The mean age was 27 (8-47) years. The procedures included prior embolization (n = 24), gamma knife before cyberknife (n = 2) and cyberknife initially (n = 25). The delineation of AVM targets was as follows: AVM with prior embolization, radiosurgical targets included AVM nidus, embolization areas and some small draining veins. However, low radiation dose was delivered to embolization parts and draining veins. For 25 patients without embolization, the radiosurgical target was AVM nidus. The mean target volume was 7.8 (1.2-22.0) cm³ and 15 of them were larger than 10.0 cm³. In patients harboring AVM with target volumes < 4 cm³, cyberknife radiation was delivered in a single session. And the remainder had 2 (n = 25) or 3 (n = 19) sessions. The mean marginal dose was 23(18-28) Gy.

RESULTS

AVM obliteration was confirmed by magnetic resonance imaging (MRI) or angiography in 40 (78%) patients during a mean follow-up of 46 (36-70) months. Marked size reduction of AVM was obtained in 11 incompletely obliterated patients. Among them, there were second cyberknife treatment (n = 3), third embolization for complex AVM (n = 1), gamma knife (n = 1) and further follow-ups (n = 6). The higher obliteration rate of AVM was correlated with small volume of AVM in noncritical areas, prior embolization and radiation target of embolization areas. Three patients had hemorrhage during the follow-up period and recovered. Brain edema was found in patients with basal ganglion or parietal AVMs. A permanent neurological deficit (paralysis) due to adverse radiation effects developed in 1 patient.

CONCLUSION

Cyberknife radiosurgery is particularly effective for patients with smaller AVMs in noncritical areas of brain. In patients with prior embolization, delineation of AVM targets including embolization areas is essential for a higher rate of obliteration.

[Clinical misdiagnosis analysis of valproate encephalopathy]

OBJECTIVE

To analyze the clinical and laboratory characteristics of postoperative patients of valproate encephalopathy (VHE), summarize the diagnostic and treatment experiences, discuss the reason of misdiagnosis and improve the level of early diagnosis.

METHODS

A total of 12 VHE patients diagnosed after an application of valproate were recruited from January 2010 to April 2013. The characteristics of clinical manifestations and laboratory examinations were retrospectively analyzed.

RESULTS

Among them, the misdiagnoses included intracranial hemorrhage (n = 1), secondary brain edema (n = 1), postoperative cerebral infarction (n = 1), postoperative epileptic deterioration (n = 4), electrolyte disorder (n = 2), intracranial infection (n = 1), vasospasm (n = 1) and non-specific (n = 1). All patients had disturbance of consciousness associated with elevated blood ammonia. The symptoms of VHE were not correlated with the dosage and concentration of valproate. VHE was more likely to occur in patients treated with valproic acid sodium injection or other antiepileptic drugs. The symptoms dramatically improved after a withdrawal of valproate.

CONCLUSION

VHE should be considered in postoperative neurosurgical valproate-treated patients with unknown disturbance of consciousness. Timely diagnosis is needed and valproate should be withdrawn to avoid serious consequences.

Hypoxia-inducible factor and vascular endothelial growth factor are targets of dietary soy during acute stroke in female rats

Dietary soy and soy isoflavones are neuroprotective in experimental cerebral ischemia. Because these isoflavones have estrogenic properties, we hypothesized that, like estrogens, they would inhibit acute vascular injury and the detrimental acute increase in hypoxia-induced vascular endothelial growth factor (VEGF) that leads to cerebral edema after stroke. Mature ovariectomized female Sprague Dawley rats were fed soy-free or soy-containing diets for 4 weeks followed by 90 minutes of transient middle cerebral artery occlusion. Similar to estrogens, dietary soy significantly reduced cerebral edema and vascular apoptosis 24 hours after stroke. Soy also inhibited the ischemia-induced increase in cortical VEGF and VEGF receptor (VEGFR)-2 protein expression observed 4 and 24 hours after stroke, although mRNA levels increased. The reduction in VEGF/VEGFR-2 was associated both with decreases in receptor phosphorylation and signaling to AKT and endothelial nitric oxide synthase. Furthermore degradation of the VEGFR-2 was increased with dietary soy. The primary ischemic stimulus for VEGF, hypoxia-inducible factor 1α (HIF1α), was similarly reduced by dietary soy 4 hours after transient middle cerebral artery occlusion in both the cortex and striatum. The inhibition of HIF1α activity was further confirmed by a significant decrease in the HIF1α-activated apoptotic mediator BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (Nip3-like protein X). These data suggest that soy isoflavones target events early in the ischemic cascade as part of their neuroprotective actions and counterbalance some of the detrimental effects of the endogenous response to cerebral injury.

Protective effect of hydroalcoholic extract of Mimusops elengi Linn. flowers against middle cerebral artery occlusion induced brain injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In the traditional Indian and Thai system of medicine, Mimusops elengi Linn., flower is used as brain tonic and to calm anxiety and panic attacks.

AIM OF THE STUDY

The present study was designed to investigate the neuroprotective effect of hydroalcoholic extract of Mimusops elengi (ME) against cerebral ischemic reperfusion injury in rats.

MATERIALS AND METHODS

Male rats were pretreated with ME (100 and 200mg/kg) for seven days and focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) method. After 60min of MCAO and 24h of reperfusion, a battery of behavioral tests assessed the extent of neurological deficits. Infarct volume and brain edema were measured in TTC stained brain sections and the extent of blood brain barrier (BBB) disruption was observed by Evan's blue extravasation. Oxidative and nitrative stress parameters were estimated in the brain homogenates. Further, simultaneous quantification of five polyphenolic biomarkers were done using HPLC.

RESULTS

Pretreatment with ME at doses of 100 and 200mg/kg significantly improved the neurobehavioral alterations and reduced the infarct volume, edema and extent of BBB disruption induced by ischemia reperfusion injury. It also prevented the alteration in the antioxidant status and reduced the nitrite levels when compared to ischemic animals. Further, HPLC studies revealed that ME contains five bioactive polyphenolic compounds.

CONCLUSIONS

These results clearly indicate the neuroprotective effect of ME against stroke like injury. The observed protective effect might be attributed to the polyphenolic compounds and their antioxidant and anti-inflammatory property.

Metabolic effects of a late hypotensive insult combined with reduced intracranial compliance following traumatic brain injury in the rat

INTRODUCTION

Traumatic brain injury makes the brain vulnerable to secondary insults. Post-traumatic alterations in intracranial dynamics, such as reduced intracranial compliance (IC), are thought to further potentiate the effects of secondary insults. Reduced IC combined with intracranial volume insults leads to metabolic disturbances in a rat model. The aim of the present study was to discern whether a post-traumatic hypotensive insult in combination with reduced IC caused more pronounced secondary metabolic disturbances in the injured rat brain.

MATERIALS AND METHODS

Rats were randomly assigned to four groups (n = 8/group): 1) trauma with hypotension; 2) trauma and reduced IC with hypotension; 3) sham injury with hypotension; and 4) sham injury and reduced IC with hypotension. A weight drop model of cortical contusion trauma was used. IC was reduced by gluing rubber film layers on the inside of bilateral bone flaps before replacement. Microdialysis probes were placed in the perimeter of the trauma zone. Hypotension was induced 2 h after trauma. Extracellular (EC) levels of lactate, pyruvate, hypoxanthine, and glycerol were analyzed.

RESULTS

The trauma resulted in a significant increase in EC dialysate levels of lactate, lactate/pyruvate ratio, hypoxanthine, and glycerol. A slight secondary increase in lactate was noted for all groups but group 2 during hypotension, otherwise no late effects were seen. There were no effects of reduced IC.

DISCUSSION

In conclusion, reduced IC did not increase the metabolic disturbances caused by the post-traumatic hypotensive insult. The results suggest that a mild to moderate hypotensive insult after initial post-traumatic resuscitation may be tolerated better than an early insult before resuscitation.

Cyclo-oxygenase-2 mediates hyperbaric oxygen preconditioning-induced neuroprotection in the mouse model of surgical brain injury

BACKGROUND AND PURPOSE

We investigated the role of cyclo-oxygenase-2 (COX-2) in mechanisms of hyperbaric oxygen preconditioning (HBO-PC) in the mouse model of surgical brain injury (SBI).

METHODS

C57BL mice were administered 100% oxygen for 1 hour at 2.5 atmosphere absolute for 5 consecutive days and subjected to SBI. Neurological status and brain edema were evaluated at 24 hours and 72 hours after the brain insult. Fluorescent immunostaining and Western blotting were performed to study hypoxia-inducible factor-1alpha and COX-2, respectively. Two doses of COX-2 inhibitor, NS398 (3 mg/kg and 10 mg/kg) were used to verify the role of COX-2 signaling pathway in the mechanism of HBO-PC.

RESULTS

HBO-PC improved neurological status and decreased brain edema at 24 hours and 72 hours after SBI. HBO-PC by itself and SBI independently increased COX-2 levels by 2-fold and 4-fold, respectively. HBO-PC, however, reduced increase in hypoxia-inducible factor-1alpha and COX-2 expression after SBI. The HBO-PC-induced improvement in neurological status and brain edema was reversed by a suboptimal dose of the COX-2 inhibitor, NS398 (10 mg/kg intraperitoneally; 1/4th of dose shown to provide neuroprotection), which itself had no effect on investigated end points.

CONCLUSIONS

HBO-PC attenuates postoperative brain edema and improves neurological outcomes after SBI. The HBO-PC-induced neuroprotection is mediated through COX-2 signaling pathways.

Can the Ischemic Penumbra Be Identified on Noncontrast CT of Acute Stroke?

Background and Purpose— Early ischemic changes on noncontrast CT in acute stroke include both hypoattenuation and brain swelling, which may have different pathophysiological significance.

Methods— Noncontrast CT and CT perfusion brain scans from patients with suspected acute stroke <6 hours after onset were reviewed. Five raters independently scored noncontrast CTs blind to clinical data using the Alberta Stroke Program Early CT Score (ASPECTS). Each ASPECTS region was scored as hypodense or swollen. A separate reviewer measured time to peak and cerebral blood volume in each ASPECTS region on CT perfusion. Time to peak and cerebral blood volume were compared for each region categorized as normal, hypodense, or isodense and swollen.

Results— Scans of 32 subjects a median 155 minutes after onset yielded 228 regions with both CT perfusion and noncontrast CT data. Isodense swelling was associated with significantly higher cerebral blood volume ( P =0.016) and with penumbral perfusion (posttest:pretest likelihood ratio 1.44 [95% CI: 0.68 to 2.90]), whereas hypodensity was associated with more severe time to peak delay and with core perfusion (likelihood ratio 3.47 [95% CI: 1.87 to 6.34]). Neither isodense swelling nor hypodensity was sensitive for prediction of perfusion pattern, but appearances were highly specific (87.2% and 91.0% for penumbra and core, respectively). Intrarater agreement was good or excellent, but interrater agreement for both hypodensity and swelling was poor.

Conclusions— Regions exhibiting hypoattenuation are likely to represent the infarct core, whereas regions that are isodense and swollen have increased cerebral blood volume and are more likely to signify penumbral perfusion. Although noncontrast CT is not sensitive for detection of core and penumbra, appearances are specific. Some information on tissue viability can therefore be obtained from noncontrast CT.

TWEAK-Fn14 pathway inhibition protects the integrity of the neurovascular unit during cerebral ischemia

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a member of the tumor necrosis factor superfamily. TWEAK acts via binding to a cell surface receptor named Fn14. To study the role of this cytokine in the regulation of the permeability of the neurovascular unit (NVU) during cerebral ischemia, TWEAK activity was inhibited in wild-type mice with a soluble Fn14-Fc decoy receptor administered either immediately or 1 h after middle cerebral artery occlusion (MCAO). Administration of Fn14-Fc decoy resulted in faster recovery of motor function and a 66.4%+/-10% decrease in Evans blue dye extravasation when treatment was administered immediately after MCAO and a 46.1%+/-13.1% decrease when animals were treated 1 h later (n=4, P<0.05). Genetic deficiency of Fn14 resulted in a 60%+/-12.8% decrease in the volume of the ischemic lesion (n=6, P<0.05), and a 87%+/-22% inhibition in Evans blue dye extravasation 48 h after the onset of the ischemic insult (n=6, P<0.005). Compared with control animals, treatment with Fn14-Fc decoy or genetic deficiency of Fn14 also resulted in a significant inhibition of nuclear factor-kappaB pathway activation, matrix metalloproteinase-9 activation and basement membrane laminin degradation after MCAO. These findings show that the cytokine TWEAK plays a role in the disruption of the structure of the NVU during cerebral ischemia and that TWEAK antagonism is a potential therapeutic strategy for acute cerebral ischemia.

[Reversible posterior leukoencephalopathy: should the area involved be in the name of the syndrome?]

INTRODUCTION

Reversible posterior leukoencephalopathy (RPL) is a syndrome of headache, vomiting and focal neurologic deficits with reversible lesions in posterior areas of the brain at the same time.

CASE REPORT

We describe the case of a patient with a background of multiple diseases presenting a syndrome compatible with reversible posterior leukoencephalopathy. He presented seizures during a hospital stay. Among his background, he had several factors that are presently considered to be involved in its etiopathogeny. The most important ones are renal failure, hypertension and immunosuppressive agents. Magnetic resonance (MR) showed radiological typical changes of RPL syndrome but not only affecting the posterior regions of the brain. We confirmed the diagnostic suspicion after complete clinical and radiological recovery of the condition, and the patient did not have new episodes after the normalization of the neuroimage.

CONCLUSIONS

We made a review of the etiopathogeny. We question the adequacy of the name of the syndrome, given the extension of the lesions in the neuroimage.

Cerebral mast cells regulate early ischemic brain swelling and neutrophil accumulation

We previously observed degranulated mast cells (MC) in association with perivascular brain edema formation during focal cerebral ischemia. Brain MC are typically located perivascularly and contain potent fast-acting vasoactive and proteolytic substances. We examined in a rat model of transient middle cerebral artery occlusion (MCAO) whether, in the early phase of ischemia, MC regulate microcirculation, the blood-brain barrier (BBB) permeability, and edema formation. First, animals received MC inhibitor (cromoglycate), MC-degranulating drug (compound 48/80), or saline. Thereafter, we performed transient MCAO in gene-manipulated MC-deficient rats and their wild-type (WT) littermates, calculating brain swelling, visualizing BBB leakage by intravenously administered Evans blue albumin, and determining neutrophil infiltration with light microscopy. Cerebral blood flow, monitored by laser-Doppler flowmetry in separate experiments, was similar among pharmacological treatments. Ischemic swelling resulted in increased hemispheric volume of 13.4%+/-1.0% in controls, 8.1%+/-0.4% (39% reduction) after cromoglycate, and 25.2%+/-2.0% (89% increase) after compound 48/80 (P<0.05). Early ischemic BBB leakage was reduced by 51% after cromoglycate, and 50% enhanced by compound 48/80 (P<0.05). The cromoglycate group showed 37% less postischemic neutrophil infiltration than did controls (P<0.05). Furthermore, MC-deficient rats responded to focal ischemia with 58% less brain swelling (6.7%+/-1.2%) than did their WT littermates (15.8%+/-1.4%, P<0.05). Blood-brain barrier damage was 47% lower in MC-deficient rats than in the WT (P<0.05). Neutrophil infiltration after MCAO was decreased 47% in MC-deficient rats in comparison to WT (P<0.05). Pharmacological MC inhibition thus appears to deserve further investigation regarding reduction of brain swelling and inflammation early after stroke.

Chronic administration of ethyl docosahexaenoate reduces gerbil brain eicosanoid productions following ischemia and reperfusion

Arachidonic acid (AA) and its vasoactive metabolites have been implicated in the pathogenesis of brain damage induced by cerebral ischemia. The membrane AA concentrations can be reduced by changes in dietary fatty acid intake. The purpose of the present study was to investigate the effects of chronic ethyl docosahexaenoate (E-DHA) administration on the generation of eicosanoids of AA metabolism during the period of reperfusion after ischemia in gerbils. Weanling male gerbils were orally pretreated with either E-DHA (100, 200 mg/kg) or vehicle, once a day, for 10 weeks, and subjected to transient forebrain ischemia by bilateral common carotid occlusion for 10 min. E-DHA (200 mg/kg) pretreatment significantly decreased the content of brain lipid AA at the termination of treatment, prevented postischemic impaired regional cerebral blood flow (rCBF) and reduced the levels of brain prostaglandin (PG) PGF(2alpha) and 6-keto-PGF(1alpha), and thromboxane B(2) (TXB(2)), as well as leukotriene (LT) LTB(4) and LTC(4) at 30 and 60 min of reperfusion compared with the vehicle, which was well associated with the attenuated cerebral edema in the E-DHA-treated brain after 48 h of reperfusion. These data suggest that the E-DHA (200 mg/kg) pretreatment reduces the postischemic eicosanoid productions, which may be due to its reduction of the brain lipid AA content.

Pathophysiology of traumatic injury in the developing brain: an introduction and short update

Current understanding about the main peculiarities in pathophysiology of immature brain traumatic injury involves marked developmental discrepancy of biomechanical properties, aspects of altered features in water and electrolyte homeostasis as well as maturation dependent differences in structural and functional responses of major transmitter systems. Based on the fact that traumatic brain injury (TBI) is one of the major causes of morbidity and mortality in infants and children, the currently available epidemiological data are reviewed in order to gain insights about scope and dimension of health care engagement and derive the requirements for reinforced pathogenetic research. To this end, the main aspects of peculiarities in primary and secondary TBI mechanisms in the immature/developing brain are discussed, including structural and functional conditions resulting in a markedly diminished shear resistance of the immature brain tissue. As such, the immature brain tissue appears to be more susceptible to mechanical alterations, because similar mechanical load induces a more intense brain tissue displacement. Furthermore, available indications for increased incidence of brain swelling in the immature brain after TBI are reviewed, focusing on the interrelationship between the age-dependent differences in extracellular space and aquaporin-4 expression during brain maturation. The developmental differences of TBI induced cerebrovascular response as well as some relevant aspects of altered neurotransmission following TBI of the immature brain in regard to the glutamatergic and dopaminergic transmitter system are assessed. Thus, this mini-review highlights some progress but also an increased necessity for expanded pathogenetic research on a clinical scale in order to develop a solid foundation for adequate therapeutic strategies for the different life-threatening consequences of TBI in infancy and childhood, which mainly have failed up to now.