Whole body hypothermia and oxidative stress in babies with hypoxic-ischemic brain injury

Ischemia-Modified Albumin and Antioxidant Protection in Newborns with Asphyxia of Varying Severity

The content of ischemia-modified albumin (IMA), serum albumin, and antioxidant capacity of blood serum was studied in healthy newborns and in newborns with moderate and severe asphyxia on days 1-2 and 3-4 of the postnatal period. Changes in these indicators were found in both groups of newborns with birth asphyxia in comparison with the group of healthy newborns and were more pronounced in children with severe asphyxia. An increase in the IMA level (by 1.6 times; p<0.001) and antioxidant capacity of blood serum (by 2.4 times; p<0.001) and a decrease in serum albumin content (by 1.5 times; p<0.001) were found in severe asphyxia on days 1-2. Analysis of changes in these indicators by days 3-4 allows to talk about a decrease in the intensity of free-radical reactions in newborns with birth asphyxia during complex therapy.

Fever burden within 24 h after hematoma evacuation predicts early neurological deterioration in patients with intracerebral hemorrhage: a retrospective analysis

Background

Early neurological deterioration after hematoma evacuation is closely associated with a poor prognosis in patients with intracerebral hemorrhage. However, the relationship between body temperature after hematoma evacuation and early neurological deterioration remains unclear. Therefore, this study aims to explore the possible relationship between body temperature and early neurological deterioration in patients with intracerebral hemorrhage after hematoma evacuation.

Methods

We retrospectively collected data from patients with cerebral hemorrhage at our institute between January 2017 and April 2022. The Student's t-test, Mann-Whitney U-test, and χ2 Test and Fisher's exact test were used to analyze the clinical baseline data. A univariate logistic regression model was used to evaluate the association between the body temperature indices and early neurological deterioration. The predictive power was assessed using the area under the Receiver Operating Characteristic (ROC) curve. The secondary outcome was a poor functional outcome.

Results

Among 2,726 patients with intracerebral hemorrhage, 308 who underwent hematoma evacuation were included in the present analysis. A total of 82 patients (22.6%) developed early neurological deterioration. Univariate analysis showed that sex (p = 0.041); body temperature at 6 h (p = 0.005), 12 h (p = 0.01), and 24 h (p = 0.008) after surgery; duration of fever (p = 0.008); and fever burden (p < 0.001) were associated with early neurological deterioration. Multivariate logistic regression showed that fever burden was independently associated with early neurological deterioration (OR = 1.055 per °C × hour, 95%CI 1.008-1.103, p = 0.020). ROC showed that fever burden (AUC = 0.590; 95%CI: 0.514-0.666) could predict the occurrence of early neurological deterioration.

Conclusion

Fever burden is associated with early neurological deterioration in intracerebral hemorrhage patients undergoing hematoma evacuation. Our findings add to previous evidence on the relationship between the fever burden and the occurrence of early neurological deterioration in patients with intracerebral hemorrhage. Future studies with larger sample sizes are required to confirm these findings.

Pyrazolone-type compounds (part II): in vitro and in silico evaluation of antioxidant potential; structure-activity relationship

The pyrazolone class comprises a variety of hybrid compounds displaying diverse biological actions. Although studied for decades, these compounds are still of interest due to their facile chemical transformations. In our previous work, we presented the synthetic route of functionalised pyrazolone derivatives. The presence of pyrazolone structural motif in many drugs, such as edaravone, prompted us to investigate the antioxidant features of the selected compounds. In this paper, we provide an extensive in vitro and in silico description of the antioxidant properties of selected pyrazolone analogues. The obtained in vitro results revealed their great antiradical potency against the DPPH radical (IC₅₀ values in the 2.6-7.8 μM range), where the best results were obtained for analogues bearing a catechol moiety. Density functional theory (DFT) was used to assess their antioxidant capacity from the thermodynamic aspect. Here, good agreement with in vitro results was achieved. DFT was employed for the prediction of the most preferable radical scavenging pathway, also. In polar solvents, the SPLET mechanism is a favourable scavenging route, whereas in nonpolar solvents the HAT is slightly predominant. Furthermore, antioxidant mechanisms were studied in the presence of relevant reactive oxygen species. The obtained values of the reaction enthalpies with the selected radicals revealed that HAT is slightly prevailing in polar solvents, while the SPLET mechanism is dominant in nonpolar solvents. Regarding the well-known antioxidant features of the drug edaravone, these findings represent valuable data for this pyrazolone class and could be used as the basis for further investigations.

Therapeutic hypothermia can cause non-infective C-reactive protein elevating

Objective

To analyze the relationship between therapeutic hypothermia (TH) and whole blood high-sensitivity C-reactive protein (hs-CRP) in neonates with hypoxic-ischemic encephalopathy (HIE).

Method

Retrospective analysis was made on the clinical data of hospitalized infants diagnosed with asphyxia in our neonatal intensive care unit from January 2014 to June 2021. According to whether TH was performed, they were divided into two groups, the control group (missed the time in other hospitals and did not receive TH) and the treatment group (TH group). In their first ten days, analysis was made on the hs-CRP, white blood cell (WBC) count, neutrophil percentage, platelet count (PLT), and brain MRI. The correlation analysis was carried out based on the severity of brain injury displayed by the brain MRI and the time of hs-CRP elevation to summarize the relationship between TH and the time of hs-CRP elevation and the severity of HIE.

Results

83 infants were included, 28 in the control group and 55 in the TH group. After birth, 33 infants (60.0%) in the TH group and 2 patients (7.1%) in the control group had elevated hs-CRP, which was statistically significant (P < 0.05). The time window for CRP elevation after TH was 72-96 h after the end of treatment; The results of the brain MRI showed 23 in the TH group and 11in the control group with moderate and severe HIE. 21 infants (all in the TH group) had elevated hs-CRP. MRI showed that the number of infants with mild injury or regular infants whose hs-CRP raised in the TH group was 12, and the rate of hs-CRP elevation was 37.5%; in the control group, the rate was 11.8%. The difference was significant. TH can decrease PLT and WBC, but no significance in the two groups. Blood and sputum cultures were negative in all infants, and there were no signs of infection.

Conclusions

TH can increase the blood hs-CRP of HIE neonates, and the probability of its occurrence is related to the severity of HIE. The heavier the HIE, the higher the risk of hs-CRP elevation after TH; The hs-CRP elevation has little to do with infection, and it doesn't recommend using antibiotics actively.

Therapeutic hypothermia for stroke: Unique challenges at the bedside

Therapeutic hypothermia has shown promise as a means to improving neurological outcomes at several neurological conditions. At the clinical level, it has been shown to improve outcomes in comatose survivors of cardiac arrest and in neonatal hypoxic ischemic encephalopathy, but has yet to be convincingly demonstrated in stroke. While numerous preclinical studies have shown benefit in stroke models, translating this to the clinical level has proven challenging. Major obstacles include cooling patients with typical stroke who are awake and breathing spontaneously but often have significant comorbidities. Solutions around these problems include selective brain cooling and cooling to lesser depths or avoiding hyperthermia. This review will cover the mechanisms of protection by therapeutic hypothermia, as well as recent progress made in selective brain cooling and the neuroprotective effects of only slightly lowering brain temperature. Therapeutic hypothermia for stroke has been shown to be feasible, but has yet to be definitively proven effective. There is clearly much work to be undertaken in this area.

Mitochondrial calcium buffering depends upon temperature and is associated with hypothermic neuroprotection against hypoxia-ischemia injury

Hypothermia (HT) is a standard of care in the management of hypoxic-ischemic brain injury (HI). However, therapeutic mechanisms of HT are not well understood. We found that at the temperature of 32°C, isolated brain mitochondria exhibited significantly greater resistance to an opening of calcium-induced permeability transition pore (mPTP), compared to 37°C. Mitochondrial calcium buffering capacity (mCBC) was linearly and inversely dependent upon temperature (25°C—37°C). Importantly, at 37°C cyclosporine A did not increase mCBC, but significantly increased mCBC at lower temperature. Because mPTP contributes to reperfusion injury, we hypothesized that HT protects brain by improvement of mitochondrial tolerance to mPTP activation. Immediately after HI-insult, isolated brain mitochondria demonstrated very poor mCBC. At 30 minutes of reperfusion, in mice recovered under normothermia (NT) or HT, mCBC significantly improved. However, at four hours of reperfusion, only NT mice exhibited secondary decline of mCBC. HT-mice maintained their recovered mCBC and this was associated with significant neuroprotection. Direct inverted dependence of mCBC upon temperature in vitro and significantly increased mitochondrial resistance to mPTP activation after therapeutic HT ex vivo suggest that hypothermia-driven inhibition of calcium-induced mitochondrial mPTP activation mechanistically contributes to the neuroprotection associated with hypothermia.

Effect of Therapeutic Hypothermia Treatment on Acute Phase Reactants

Objective In our study, we aimed to examine the effect of therapeutic hypothermia treatment on C-reactive protein (CRP) and interleukin-6 (IL-6) in infants with hypoxic ischemic encephalopathy (HIE).

Methods The data of the patients with the diagnosis of HIE we followed up in our unit between 2017 and 2018 were analyzed retrospectively. Patients who died during follow-up and patients with proven septicemia at the time of examination were excluded from the study. The routine CRP and IL-6 values ​​of the patients included in the study were compared before and after hypothermia treatment.

Results Therapeutic hypothermia treatment applied for 72 hours was found to cause a statistically significant increase in CRP after treatment when compared with the values ​​measured before treatment (0.6 (0.2–1.9) before and median (P25–75), and after treatment 7.5 (4–18) and median (P25–75) mg/L, p=0.00). While IL-6 was found to be high in the early period due to the effect of hypoxia, it was found to be low after hypothermia treatment (80.5 (40–200) median (P25–75) – 32 (18–50) median (P25–75) pg/ml, p=0.131). While the white blood cell count was high before hypothermia treatment due to hypoxia, it was found to be low after treatment (24600 (19600–30100) median (P25–75) –11300 (8800–14200) median (P25–75)/µL, p=0.001).

Conclusion White blood cells and IL-6 can be found to be high due to hypoxia without infection, and CRP can be found to be high after therapeutic hypothermia treatment without infection. The effect of hypoxia and hypothermia should be considered when evaluating acute phase reactants.

Therapeutic hypothermia in neonatal hypoxic encephalopathy: A systematic review and meta-analysis

Background

Therapeutic hypothermia (TH) is regarded as the most efficacious therapy for neonatal hypoxic encephalopathy. However, limitations in previous systematic reviews and the publication of new data necessitate updating the evidence. We conducted this up-to-date systematic review to evaluate the effects of TH in neonatal encephalopathy on clinical outcomes.

Methods

In this systematic review and meta-analysis, we searched Medline, Cochrane Library, Embase, LIVIVO, Web of Science, Scopus, CINAHL, major trial registries, and grey literature (from inception to October 31, 2021), for randomized controlled trials (RCT) comparing TH vs normothermia in neonatal encephalopathy. We included RCTs enrolling neonates (gestation ≥35 weeks) with perinatal asphyxia and encephalopathy, who received either TH (temperature ≤34°C) initiated within 6 hours of birth for ≥48 hours, vs no cooling. We excluded non-RCTs, those with delayed cooling, or cooling to >34°C. Two authors independently appraised risk-of-bias and extracted data on mortality and neurologic disability at four time points: neonatal (from randomization to discharge/death), infancy (18-24 months), childhood (5-10 years), and long-term (>10 years). Other outcomes included seizures, EEG abnormalities, and MRI findings. Summary data from published RCTs were pooled through fixed-effect meta-analysis.

Results

We identified 36 863 citations and included 39 publications representing 29 RCTs with 2926 participants. Thirteen studies each had low, moderate, and high risk-of-bias. The pooled risk ratios (95% confidence interval, CI) were as follows: neonatal mortality: 0.87 (95% CI = 0.75, 1.00), n = 2434, I² = 38%; mortality at 18-24 months: 0.88 (95% CI = 0.78, 1.01), n = 2042, I² = 51%; mortality at 5-10 years: 0.81 (95% CI = 0.62, 1.04), n = 515, I² = 59%; disability at 18-24 months: 0.62 (95% CI = 0.52, 0.75), n = 1440, I² = 26%; disability at 5-10 years: 0.68 (95% CI = 0.52, 0.90), n = 442, I² = 3%; mortality or disability at 18-24 months: 0.78 (95% CI = 0.72, 0.86), n = 1914, I² = 54%; cerebral palsy at 18-24 months: 0.63 (95% CI = 0.50, 0.78), n = 1136, I² = 39%; and childhood cerebral palsy: 0.63 (95% CI = 0.46, 0.85), n = 449, I² = 0%. Some outcomes showed significant differences by study-setting; the risk ratio (95% CI) for mortality at 18-24 months was 0.79 (95% CI = 0.66,0.93), n = 1212, I² = 7% in high-income countries, 0.67 (95% CI = 0.41, 1.09), n = 276, I² = 0% in upper-middle-income countries, and 1.18 (95% CI = 0.94, 1.47), n = 554, I² = 75% in lower-middle-income countries. The corresponding pooled risk ratios for ‘mortality or disability at 18-24 months’ were 0.77 (95% CI = 0.69, 0.86), n = 1089, I² = 0%; 0.56 (95% CI = 0.41, 0.78), n = 276, I² = 30%; and 0.92 (95% CI = 0.77, 1.09), n = 549, I² = 86% respectively. Trials with low risk of bias showed risk ratio of 0.97 (95% CI = 0.80, 1.16, n = 1475, I² = 62%) for neonatal mortality, whereas trials with higher risk of bias showed 0.71 (95% CI = 0.55, 0.91), n = 959, I² = 0%. Likewise, risk ratio for mortality at 18-24 months was 0.96 (95% CI = 0.83, 1.13), n = 1336, I² = 58% among low risk-of-bias trials, but 0.72 (95% CI = 0.56, 0.92), n = 706, I² = 0%, among higher risk of bias trials.

Conclusions

Therapeutic hypothermia for neonatal encephalopathy reduces neurologic disability and cerebral palsy, but its effect on neonatal, infantile and childhood mortality is uncertain. The setting where it is implemented affects the outcomes. Low(er) quality trials overestimated the potential benefit of TH.

Effects of Hypothermia and Allopurinol on Oxidative Status in a Rat Model of Hypoxic Ischemic Encephalopathy

Hypoxic ischemic encephalopathy (HIE) is one of the main causes of morbidity and mortality during the neonatal period, despite treatment with hypothermia. There is evidence that oxidative damage plays an important role in the pathophysiology of hypoxic-ischemic (HI) brain injury. Our aim was to investigate whether postnatal allopurinol administration in combination with hypothermia would reduce oxidative stress (OS) biomarkers in an animal model of HIE. Postnatal 10-day rat pups underwent unilateral HI of moderate severity. Pups were randomized into: Sham operated, hypoxic-ischemic (HI), HI + allopurinol (HIA), HI + hypothermia (HIH), and HI + hypothermia + allopurinol (HIHA). Biomarkers of OS and antioxidants were evaluated: GSH/GSSG ratio and carbonyl groups were tested in plasma. Total antioxidant capacity (TAC) was analyzed in plasma and cerebrospinal fluid, and 8-iso-prostaglandin F2α was measured in brain tissue. Plasma 2,2′–azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) levels were preserved in those groups that received allopurinol and dual therapy. In cerebrospinal fluid, only the HIA group presented normal ferric reducing ability of plasma (FRAP) levels. Protein oxidation and lipid peroxidation were significantly reduced in all groups treated with hypothermia and allopurinol, thus enhancing neuroprotection in HIE.

Brain vulnerability and viability after ischaemia

The susceptibility of the brain to ischaemic injury dramatically limits its viability following interruptions in blood flow. However, data from studies of dissociated cells, tissue specimens, isolated organs and whole bodies have brought into question the temporal limits within which the brain is capable of tolerating prolonged circulatory arrest. This Review assesses cell type-specific mechanisms of global cerebral ischaemia, and examines the circumstances in which the brain exhibits heightened resilience to injury. We suggest strategies for expanding such discoveries to fuel translational research into novel cytoprotective therapies, and describe emerging technologies and experimental concepts. By doing so, we propose a new multimodal framework to investigate brain resuscitation following extended periods of circulatory arrest.

Microglia-leucocyte axis in cerebral ischaemia and inflammation in the developing brain

Development of the Central Nervous System (CNS) is reliant on the proper function of numerous intricately orchestrated mechanisms that mature independently, including constant communication between the CNS and the peripheral immune system. This review summarizes experimental knowledge of how cerebral ischaemia in infants and children alters physiological communication between leucocytes, brain immune cells, microglia and the neurovascular unit (NVU)-the "microglia-leucocyte axis"-and contributes to acute and long-term brain injury. We outline physiological development of CNS barriers in relation to microglial and leucocyte maturation and the plethora of mechanisms by which microglia and peripheral leucocytes communicate during postnatal period, including receptor-mediated and intracellular inflammatory signalling, lipids, soluble factors and extracellular vesicles. We focus on the "microglia-leucocyte axis" in rodent models of most common ischaemic brain diseases in the at-term infants, hypoxic-ischaemic encephalopathy (HIE) and focal arterial stroke and discuss commonalities and distinctions of immune-neurovascular mechanisms in neonatal and childhood stroke compared to stroke in adults. Given that hypoxic and ischaemic brain damage involve Toll-like receptor (TLR) activation, we discuss the modulatory role of viral and bacterial TLR2/3/4-mediated infection in HIE, perinatal and childhood stroke. Furthermore, we provide perspective of the dynamics and contribution of the axis in cerebral ischaemia depending on the CNS maturational stage at the time of insult, and modulation independently and in consort by individual axis components and in a sex dependent ways. Improved understanding on how to modify crosstalk between microglia and leucocytes will aid in developing age-appropriate therapies for infants and children who suffered cerebral ischaemia.

HSP70-mediated neuroprotection by combined treatment of valproic acid with hypothermia in a rat asphyxial cardiac arrest model

It has been reported that valproic acid (VPA) combined with therapeutic hypothermia can improve survival and neurologic outcomes in a rat asphyxial cardiac arrest model. However, neuroprotective mechanisms of such combined treatment of valproic acid with hypothermia remains unclear. We hypothesized that epigenetic regulation of HSP70 by histone acetylation could increase HSP70-mediated neuroprotection suppressed under hypothermia. Male Sprague-Dawley rats that achieved return of spontaneous circulation (ROSC) from asphyxial cardiac arrest were randomized to four groups: normothermia (37°C ± 1°C), hypothermia (33°C ± 1°C), normothermia + VPA (300 mg/kg IV initiated 5 minutes post-ROSC and infused over 20 min), and hypothermia + VPA. Three hours after ROSC, acetyl-histone H3 was highly expressed in VPA-administered groups (normothermia + VPA, hypothermia + VPA). Four hours after ROSC, HSP70 mRNA expression levels were significantly higher in normothermic groups (normothermia, normothermia + VPA) than in hypothermic groups (hypothermia, hypothermia + VPA). The hypothermia + VPA group showed significantly higher HSP70 mRNA expression than the hypothermia group. Similarly, at five hours after ROSC, HSP70 protein levels were significantly higher in normothermic groups than in hypothermic groups. HSP70 levels were significantly higher in the hypothermia + VPA group than in the hypothermia group. Only the hypothermia + VPA group showed significantly attenuated cleaved caspase-9 levels than the normothermia group. Hypothermia can attenuate the expression of HSP70 at transcriptional level. However, VPA administration can induce hyperacetylation of histone H3, leading to epigenetic transcriptional activation of HSP70 even in a hypothermic status. Combining VPA treatment with hypothermia may compensate for reduced activation of HSP70-mediated anti-apoptotic pathway.

Dietary nutrition for neurological disease therapy: Current status and future directions

Adequate food intake and relative abundance of dietary nutrients have undisputed effects on the brain function. There is now substantial evidence that dietary nutrition aids in the prevention and remediation of neurologic symptoms in diverse pathological conditions. The newly described influences of dietary factors on the alterations of mitochondrial dysfunction, epigenetic modification and neuroinflammation are important mechanisms that are responsible for the action of nutrients on the brain health. In this review, we discuss the state of evidence supporting that distinct dietary interventions including dietary supplement and dietary restriction have the ability to tackle neurological disorders using Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, Huntington's disease and multiple sclerosis as examples. Additionally, it is also highlighting that diverse potential mechanisms such as metabolic control, epigenetic modification, neuroinflammation and gut-brain axis are of utmost importance for nutrient supply to the risk of neurologic condition and therapeutic response. Finally, we also highlight the novel concept that dietary nutrient intervention reshapes metabolism-epigenetics-immunity cycle to remediate brain dysfunction. Targeting metabolism-epigenetics-immunity network will delineate a new blueprint for combating neurological weaknesses.

Crocin enhances hypothermia therapy in hypoxic ischemia-induced brain injury in mice

Hypoxic-ischemic encephalopathy (HIE) is a serious medical situation at labor which leads to severe brain damage. Hypothermia therapy is the standard treatment for infants with HIE, but the efficacy is limited. Combination treatments are considered to enhance the efficacy of hypothermia. Crocin is an extract from saffron which has anti-inflammatory, anti-oxidant, and neuroprotective properties. The present study sought to investigate whether crocin could act as a combined treatment with hypothermia in a mouse model of HIE. C57BL/6J mice at post-natal day 7 were subjected to left common carotid artery ligation, followed by treatment of crocin (10 mg/kg) and hypothermia, either alone or in combination. Brain edema and tissue infarct were measured to evaluate brain damage. Mediators involved in inflammatory response and oxidative stress were measured. Neurological severity score test was performed to evaluate the functional outcome. Results show that crocin treatment alone could reduce inflammation and brain damage after hypoxia-ischemia. Combined treatment of crocin and hypothermia exerted enhanced therapeutic effect compared with single treatment, resulting in significantly less brain damage, reduced inflammatory and oxidative responses, and improved functional outcome. Together, these data suggest that crocin plays a beneficial effect in the mouse model of HIE. It could also enhance the neuroprotective effect of hypothermia and might be considered as a combination therapeutic treatment with hypothermia in HIE.

How to Improve the Antioxidant Defense in Asphyxiated Newborns-Lessons from Animal Models

Oxygen free radicals have been implicated in brain damage after neonatal asphyxia. In the early phase of asphyxia/reoxygenation, changes in antioxidant enzyme activity play a pivotal role in switching on and off the cascade of events that can kill the neurons. Hypoxia/ischemia (H/I) forces the brain to activate endogenous mechanisms (e.g., antioxidant enzymes) to compensate for the lost or broken neural circuits. It is important to evaluate therapies to enhance the self-protective capacity of the brain. In animal models, decreased body temperature during neonatal asphyxia has been shown to increase cerebral antioxidant capacity. However, in preterm or severely asphyxiated newborns this therapy, rather than beneficial seems to be harmful. Thus, seeking new therapeutic approaches to prevent anoxia-induced complications is crucial. Pharmacotherapy with deferoxamine (DFO) is commonly recognized as a beneficial regimen for H/I insult. DFO, via iron chelation, reduces oxidative stress. It also assures an optimal antioxidant protection minimizing depletion of the antioxidant enzymes as well as low molecular antioxidants. In the present review, some aspects of recently acquired insight into the therapeutic effects of hypothermia and DFO in promoting neuronal survival after H/I are discussed.

Hypothermia Plus Melatonin in Asphyctic Newborns: A Randomized-Controlled Pilot Study

OBJECTIVES

To investigate the effect of adding melatonin to hypothermia treatment on neurodevelopmental outcomes in asphyctic newborns.

DESIGN

Pilot multicenter, randomized, controlled, double-blind clinical trial. Statistical comparison of results obtained in two intervention arms: hypothermia plus placebo and hypothermia plus melatonin.

SETTING

Level 3 neonatal ICU.

PATIENTS

Twenty-five newborns were recruited.

INTERVENTIONS

The hypothermia plus melatonin patients received a daily dose of IV melatonin, 5 mg per kg body weight, for 3 days. General laboratory variables were measured both at neonatal ICU admission and after intervention. All infants were studied with amplitude-integrated electroencephalography and brain MRI within the first week of life. The neurodevelopmental Bayley III test, the Gross Motor Function Classification System, and the Tardieu scale were applied at the ages of 6 and 18 months.

MEASUREMENTS AND MAIN RESULTS

Clinical characteristics, laboratory evaluations, MRI findings, and amplitude-integrated electroencephalography background did not differ between the treatment groups. The newborns in the hypothermia plus melatonin group achieved a significantly higher composite score for the cognitive section of the Bayley III test at 18 months old, with respect to the hypothermia plus placebo group (p = 0.05). There were no differences between the groups according to the Gross Motor Function Classification System and Tardieu motor assessment scales.

CONCLUSIONS

The early addition of IV melatonin to asphyctic neonates is feasible and may improve long-term neurodevelopment. To our knowledge, this is the first clinical trial to analyze the administration of IV melatonin as an adjuvant therapy to therapeutic hypothermia.

Free radicals and neonatal encephalopathy: mechanisms of injury, biomarkers, and antioxidant treatment perspectives

Neonatal encephalopathy (NE), most commonly a result of the disruption of cerebral oxygen delivery, is the leading cause of neurologic disability in term neonates. Given the key role of free radicals in brain injury development following hypoxia-ischemia-reperfusion, several oxidative biomarkers have been explored in preclinical and clinical models of NE. Among these, antioxidant enzyme activity, uric acid excretion, nitric oxide, malondialdehyde, and non-protein-bound iron have shown promising results as possible predictors of NE severity and outcome. Owing to high costs and technical complexity, however, their routine use in clinical practice is still limited. Several strategies aimed at reducing free radical production or upregulating physiological scavengers have been proposed for NE. Room-air resuscitation has proved to reduce oxidative stress following perinatal asphyxia and is now universally adopted. A number of medications endowed with antioxidant properties, such as melatonin, erythropoietin, allopurinol, or N-acetylcysteine, have also shown potential neuroprotective effects in perinatal asphyxia; nevertheless, further evidence is needed before these antioxidant approaches could be implemented as standard care.

Early predictors of perinatal brain damage: the role of neurobiomarkers

The early detection of perinatal brain damage in preterm and term newborns (i.e. intraventricular hemorrhage, periventricular leukomalacia and perinatal asphyxia) still constitute an unsolved issue. To date, despite technological improvement in standard perinatal monitoring procedures, decreasing the incidence of perinatal mortality, the perinatal morbidity pattern has a flat trend. Against this background, the measurement of brain constituents could be particularly useful in the early detection of cases at risk for short-/long-term brain injury. On this scenario, the main European and US international health-care institutions promoted perinatal clinical and experimental neuroprotection research projects aimed at validating and including a panel of biomarkers in the clinical guidelines. Although this is a promising attempt, there are several limitations that do not allow biomarkers to be included in standard monitoring procedures. The main limitations are: (i) the heterogeneity of neurological complications in the perinatal period, (ii) the small cohort sizes, (iii) the lack of multicenter investigations, (iv) the different techniques for neurobiomarkers assessment, (iv) the lack of consensus for the validation of assays in biological fluids such as urine and saliva, and (v), the lack of reference curves according to measurement technique and biological fluid. In the present review we offer an up-to-date overview of the most promising developments in the use of biomarkers in the perinatal period such as calcium binding proteins (S100B protein), vasoactive agents (adrenomedullin), brain biomarkers (activin A, neuron specific enolase, glial fibrillary acidic protein, ubiquitin carboxyl-terminal hydrolase-L1) and oxidative stress markers.

Therapeutic Hypothermia Protects Against Heat Stroke-Induced Arterial Hypotension via Promoting Left Ventricular Performance in Rats

We aimed to ascertain whether therapeutic hypothermia (TH) acts as cardioprotective management for heat stroke (HS). Adult male rats under general anesthesia were exposed to whole-body heating (43°C for 70 min) to induce HS. Rats with HS displayed hyperthermia (core body temperature 42°C vs. 36°C); hypotension (30 mmHg vs. 90 mmHg mean arterial blood pressure); suppressed left ventricular (LV) performance (stroke volume 52 μl/min vs. 125 μl/min), ejection fraction (0.29% vs. 0.69%), relaxation factor (72 ms vs. 12 ms), and arterial elastance (0.31 mmHg/ μl vs. 10 mmHg/ μl); increased myocardial injury markers (e.g., creatine kinase-MB: 86 U/L vs. 24 U/L, cardiac troponin I: 3.08 ng/ml vs. 0.57 ng/ml); increased myocardial oxidative stress markers (e.g., malondialdehyde: 6.52 nmol/mg vs. 1.06 nmol/mg, thiobarbituric acid-reactive substances: 29 nmol/g vs. 2 nmol/g); decreased myocardial antioxidants (e.g., superoxide dismutase: 6 unit/mg vs. 17 unit/mg, reduced glutathione: 0.64 nmol/mg vs. 2.53 nmol/mg); increased myocardial proinflammatory cytokines (e.g., tumor necrosis factor-α 3200 pg/ml vs. 1000 pg/ml, interleukin-6: 668 pg/ml vs. 102 pg/ml); and increased cardiac damage scores (2.2 vs. 0.3). TH therapy significantly reversed the following conditions: HS-induced hyperthermia (37.5°C core body temperature), hypotension (71 mmHg), suppressed LV performance (stroke volume: 97 μl/min, ejection fraction: 0.65%, relaxation factor: 39 ms, and arterial elastance: 0.99 mmHg/μl), increased myocardial injury markers (e.g., creatine kinase-MB: 37 U/L, cardiac troponin I: 1.06 ng/ml), increased myocardial oxidative stress markers (e.g., malondialdehyde: 2.68 nmol/mg, thiobarbituric acid-reactive substances: 12.3 nmol/g), decreased myocardial antioxidants (e.g., superoxide dismutase: 13.3 unit/mg, reduced glutathione: 2.71 mmol/mg), increased myocardial proinflammatory cytokines (e.g., tumor necrosis factor-α 1500 pg/ml, interleukin-6: 108 ng/ml); and increased cardiac damage scores (0.9). We thus conclude that TH protects against HS-induced arterial hypotension by promoting LV performance in rats. These results add to the literature regarding the use of TH as cardioprotective management for HS.

Oxidative stress markers in neonatal respiratory distress syndrome: advanced oxidation protein products and 8-hydroxy-2-deoxyguanosine in relation to disease severity

OBJECTIVE

We assessed oxidant-antioxidant status and evaluated the role of lipid peroxidation, oxidative DNA damage, and protein oxidation in the development and severity of neonatal respiratory distress syndrome (RDS).

METHODS

Forty preterm neonates with RDS were compared with another 40 preterm neonates without RDS enrolled as controls. Total antioxidant capacity (TAC), malondialdehyde (MDA), advanced oxidation protein products (AOPPs), 8-hydroxy-2-deoxyguanosine (8-OHdG), and trace elements (copper and zinc) were measured in cord blood (day 0) for all neonates and repeated on day 3 for the RDS group.

RESULTS

Day 0 serum levels of MDA, AOPPs, and 8-OHdG were significantly higher in neonates with RDS than controls with a further increase on day 3. Days 0 and 3 levels of TAC, copper, and zinc were significantly lower in the RDS group compared with controls. Elevated serum levels of 8-OHdG and AOPPs were associated with severe RDS, invasive mechanical ventilation, and high mortality rate. 8-OHdG and AOPPs were positively correlated with MDA, oxygenation index, duration of ventilation, and duration of hospitalization.

CONCLUSIONS

Increased lipid, protein, and DNA oxidation is accompanied by alterations in the antioxidant defense status, which may play a role in the pathogenesis and severity of RDS.

Combined application of hypothermia and medical gases in cerebrovascular diseases

Cerebrovascular diseases have a heavy burden on society and the family. At present, in the treatment of cerebrovascular diseases, the recognized effective treatment method is a thrombolytic therapy after cerebral infarction, but limited to the time window problem, many patients cannot benefit. Other treatments for cerebrovascular disease are still in the exploration stage. The study found that medical gas and hypothermia have brain protection effects. Further research found that when the two are used in combination, the therapeutic effect has a superimposed effect. This article reviews the current research progress of hypothermia therapy combined with medical gas therapy for cerebrovascular disease.

Acquired sensorineural hearing loss in children: current research and therapeutic perspectives

The knowledge of mechanisms responsible for acquired sensorineural hearing loss in children, such as viral and bacterial infections, noise exposure, aminoglycoside and cisplatin ototoxicity, is increasing and progressively changing the clinical management of affected patients. Viral infections are by far the most relevant cause of acquired hearing loss, followed by aminoglycoside and platinum derivative ototoxicity; moreover, cochlear damage induced by noise overexposure, mainly in adolescents, is an emerging topic. Pharmacological approaches are still challenging to develop a truly effective cochlear protection; however, the use of steroids, antioxidants, antiviral drugs and other small molecules is encouraging for clinical practice. Most of evidence on the effectiveness of antioxidants is still limited to experimental models, while the use of corticosteroids and antiviral drugs has a wide correspondence in literature but with controversial safety. Future therapeutic perspectives include innovative strategies to transport drugs into the cochlea, such as molecules incorporated in nanoparticles that can be delivered to a specific target. Innovative approaches also include the gene therapy designed to compensate for abnormal genes or to make proteins by introducing genetic material into cells; finally, regenerative medicine (including stem cell approaches) may play a central role in the upcoming years in hearing preservation and restoration even if its role in the inner ear is still debated.

Regionally Impaired Redox Homeostasis in the Brain of Rats Subjected to Global Perinatal Asphyxia: Sustained Effect up to 14 Postnatal Days

The present report evaluates the effect of global perinatal asphyxia on several parameters of oxidative stress and cell viability in rat brain tissue sampled at an extended neonatal period up to 14 days, a period characterised by intensive neuritogenesis, synaptogenesis, synaptic consolidation, pruning and delayed cell death. Perinatal asphyxia was induced by immersing foetus-containing uterine horns removed by a caesarean section from on term rat dams into a water bath at 37 °C for 21 min. Asphyxia-exposed and sibling caesarean-delivered foetuses were manually resucitated and nurtured by surrogate dams for 1 to 14 postnatal (P) days. Brain samples (mesencephalon, telencephalon and hippocampus) were assayed for glutathione (reduced and oxidated levels; spectrophotometry), tissue reducing capacity (potassium ferricyanide reducing assay, FRAP), catalase (the key enzyme protecting against oxidative stress and reactive oxygen species, Western blots and ELISA) and cleaved caspase-3 (the key executioner of apoptosis, Western blots) levels. It was found that global PA produced a regionally specific and sustained increase in GSSG/GSH ratio, a regionally specific decrease in tissue reducing capacity and a regionally and time specific decrease of catalase activity and increase of cleaved caspase-3 levels. The present study provides evidence for regionally impaired redox homeostasis in the brain of rats subjected to global PA, an effect observed up to P14, mainly affecting mesencephalon and hippocampus, suggesting a sustained oxidative stress after the posthypoxia period. The oxidative stress observed postnatally can in part be associated to a respiratory apneic-like deficit, since there was a statistically significant decrease in respiration frequency in AS compared to CS neonates, also up to P14, together with the signs of a decreased peripheral blood perfusion (pink-blue skin colour in AS, compared to the pink colour observed in all CS neonates). It is proposed that PA implies a long-term metabolic insult, triggered by the length of hypoxia, the resuscitation/reoxigenation manoevres, but also by the developmental stage of the affected brain regions, and the integrity of cardiovascular and respiratory physiological functions, which are fundamental for warrantying a proper development.

Early Prediction of Hypoxic-Ischemic Brain Injury by a New Panel of Biomarkers in a Population of Term Newborns

This research paper is aimed at evaluating the predictive role of a default panel of oxidative stress (OS) biomarkers for the early identification of infants at high risk of HIE and their validation through the correlation with MRI findings. A multicenter prospective observational study was performed between March 2012 and April 2015 in two European tertiary NICUs. Eighty-four term infants at risk for HIE (pH < 7, BE < −13 mmol/L, and 5′ Apgar < 5) were enrolled. Three were excluded for chromosomal abnormalities and one due to lack of blood samples. The final population was divided according to the severity of perinatal hypoxia into 2 groups: mild/moderate HIE and severe HIE. Advanced oxidation protein products (AOPP), non-protein-bound iron (NPBI), and F2-isoprostanes (F2-IsoPs) were measured in blood samples at P1 (4–6 hours), P2 (24–72 hours), and P3 (5 days), in both groups. MRIs were scored for the severity of brain injury, using a modified Barkovich score. The mean GA was 39.8 weeks (SD 1.4) and the mean birth weight 3538 grams (SD 660); 37 were females and 43 males. Significantly lower 5′ Apgar score, pH, and BE and higher Thompson score were found in group II compared to group I at birth. Group II showed significantly higher AOPP and NPBI levels than group I (mean (SD) AOPP: 15.7 (15.5) versus 34.1 (39.2), p = 0.033; NPBI 1.1 (2.5) versus 3.9 (4.4), p = 0.013) soon after birth (P1). No differences were observed in OS biomarker levels between the two groups at P2 and P3. A regression model, including adjustment for hypothermia treatment, gender, and time after birth, showed that AOPP levels and male gender were both risk factors for higher brain damage scores (AOPP: OR 3.6, 95% CI (1.1–12.2) and gender: OR 5.6, 95% CI (1.2–25.7), resp.). Newborns with severe asphyxia showed higher OS than those with mild asphyxia at birth. AOPP are significantly associated with the severity of brain injury assessed by MRI, especially in males.

Tanshinone IIA improves hypoxic ischemic encephalopathy through TLR‑4‑mediated NF‑κB signal pathway

Hypoxic ischemic encephalopathy (HIE) is the most common brain injury following hypoxia and/or ischemia caused by various factors during the perinatal period, resulting in detrimental neurological deficits in the nervous system. Tanshinone IIA (Tan‑IIA) is a potential agent for the treatment of cardiovascular and cerebrovascular diseases. In this study, the efficacy of Tan‑IIA was investigated in a newborn mouse model of HIE. The dynamic mechanism of Tan‑IIA was also investigated in the central nervous system of neonate mice. Intravenous injection of Tan‑IIA (5 mg/kg) was administered and changes in oxidative stress, inflammation and apoptosis‑associated proteins in neurons. Histology and immunohistochemistry was used to determine infarct volume and the number of damaged neurons by Fluoro‑Jade C staining. The effects of Tan‑IIA on mice with HIE were evaluated by body weight, brain water content, neurobehavioral tests and blood‑brain barrier permeability. The results demonstrated that the apoptosis rate was decreased following Tan‑IIA administration. Expression levels of pro‑apoptotic proteins, caspase‑3 and caspase‑9 and P53 were downregulated. Expression of Bcl‑2 anti‑apoptotic proteins was upregulated by Tan‑IIA treatment in neuro. Results also found that Tan‑IIA treatment decreased production of inflammatory cytokines such as interleukin‑1, tumor necrosis factor‑α, C‑X‑C motif chemokine 10, and chemokine (C‑C motif) ligand 12. Oxidative stress was also reduced by Tan‑IIA in neurons, as determined by the expression levels of superoxide dismutase, glutathione and catalase, and the production of reactive oxygen species. The results demonstrated that Tan‑IIA treatment reduced the infarct volume and the number of damaged neurons. Furthermore, body weight, brain water content and blood‑brain barrier permeability were markedly improved by Tan‑IIA treatment of newborn mice following HIE. Furthermore, the results indicated that Tan‑IIA decreased Toll‑like receptor‑4 (TLR‑4) and nuclear factor‑κB (NF‑κB) expression in neurons. TLR‑4 treatment of neuronal cell in vitro addition stimulated NF‑κB activity, and further enhanced the production of inflammatory cytokines and oxidative stress levels in neurons. In conclusion, these results suggest that Tan‑IIA treatment is beneficial for improvement of HIE through TLR‑4‑mediated NF‑κB signaling.

Varying Evidence on Deep Hypothermic Circulatory Arrest in Thoracic Aortic Aneurysm Surgery

Cardiovascular surgeons have long debated the safe duration of deep hypothermic circulatory arrest during thoracic aortic aneurysm surgery. The rationale for using adjunctive cerebral perfusion (or not) is to achieve the best technical aortic repair with the lowest risk of morbidity and death. In this literature review, we highlight the debates surrounding these issues, evaluate the disparate findings on deep hypothermic circulatory arrest durations and temperatures, and consider the usefulness of adjunctive perfusion.

Effect of Concurrent Src Kinase Inhibition with Short-Duration Hypothermia on Ca2+/Calmodulin Kinase IV Activity and Neuropathology after Hypoxia-Ischemia in the Newborn Swine Brain

BACKGROUND

Hypoxia-ischemia (HI) results in increased activation of Ca2+/calmodulin kinase IV (CaM kinase IV) mediated by Src kinase. Therapeutic hypothermia ameliorates neuronal injury in the newborn.

HYPOTHESIS

Inhibition of Src kinase concurrently with hypothermia further attenuates the hypoxia-induced increased activation of CaM kinase IV compared with hypothermia alone.

DESIGN/METHODS

Ventilated piglets were exposed to HI, received saline or a selective Src kinase inhibitor (PP2), and were cooled to 33°C. Neuropathology, adenosine triphosphate (ATP) and phosphocreatine (PCr) concentrations, and CaM kinase IV activity were determined.

RESULTS

The neuropathology mean score (mean ± SD) was 0.4 ± 0.43 in normoxia-normothermia (p < 0.05 vs. hypoxia-normothermia), 3.5 ± 0.89 in hypoxia-normothermia (p < 0.05 vs. normoxia-normothermia), 0.7 ± 0.73 in hypoxia-hypothermia (p < 0.05 vs. normoxia-normothermia), and 0.5 ± 0.70 in normoxia-hypothermia (p < 0.05 vs. hypoxia-normothermia). The CaM kinase IV activity in cerebral tissue (pmol Pi/mg protein/min; mean ± SD) was 2,002 ± 729 in normoxia-normothermia, 1,704 ± 18 in normoxia-hypothermia, 6,017 ± 2,510 in hypoxia-normothermia, 4,104 ± 542 in hypoxia-hypothermia (p < 0.05 vs. normoxia-hypothermia), and 2,165 ± 415 in hypoxia-hypothermia with PP2 (p < 0.05 vs. hypoxia-hypothermia). The hypoxic groups with and without hypothermia or Src kinase inhibitor were comparable in the levels of ATP and PCr, indicating that they were similar in their degree of energy failure prior to treatments. Hypothermia or Src kinase inhibitor (PP2) did not restore the ATP and PCr levels.

CONCLUSIONS

Hypothermia and Src kinase inhibition attenuated apoptotic cell death and improved neuropathology after hypoxia. The combination of short-duration hypothermia with Src kinase inhibition following hypoxia further attenuates the increased activation of CaM kinase IV compared to hypothermia alone in the newborn swine brain.

Role of Perinatal Inflammation in Neonatal Arterial Ischemic Stroke

Based on the review of the literature, perinatal inflammation often induced by infection is the only consistent independent risk factor of neonatal arterial ischemic stroke (NAIS). Preclinical studies show that acute inflammatory processes take place in placenta, cerebral arterial wall of NAIS-susceptible arteries and neonatal brain. A top research priority in NAIS is to further characterize the nature and spatiotemporal features of the inflammatory processes involved in multiple levels of the pathophysiology of NAIS, to adequately design randomized control trials using targeted anti-inflammatory vasculo- and neuroprotective agents.

Biomarkers of hepatic injury and function in neonatal hypoxic ischemic encephalopathy and with therapeutic hypothermia

Therapeutic hypothermia (TH) is now provided as standard care to infants with moderate-severe hypoxic ischemic encephalopathy (HIE). The role of TH in limiting neuronal injury is well recognized, but its effect on hepatic injury which occurs frequently in neonatal HIE is not known. Our objective was to characterize biomarkers of liver injury and function in the setting of neonatal HIE and to describe whether HIE severity and provision of TH influence these hepatic biomarkers. We performed a multicenter retrospective study and compared hepatic biomarkers obtained during the first postnatal week, according to the severity of HIE and whether treated with TH. Of a total of 361 infants with HIE, 223 (62%) received TH and 138 (38%) were managed at normal temperature. Most hepatic biomarkers and C-reactive protein (CRP) were significantly associated with the severity of HIE (p < 0.001). Infants treated with TH had lower peak alanine aminotransferase (ALT) concentrations (p = 0.025) and a delay in reaching peak CRP concentration (p < 0.001).

CONCLUSION

We observed a significant association between the clinical grade of HIE and biomarkers of liver metabolism and function. Therapeutic hypothermia was associated with delayed CRP responses and with lower ALT concentrations and so may have the potential to modulate hepatic injury. What is Known: • Ischemic hepatic injury occurs frequently as a part of multiorgan dysfunction in infants with hypoxic ischemic encephalopathy (HIE). • The neuroprotective role of therapeutic hypothermia in management of infants with HIE is well recognized, but the potential hepato-protective effects of hypothermia are unclear. What is New/What this study adds: • Therapeutic hypothermia was associated with lower alanine aminotransferase and albumin concentrations and a delayed C-reactive protein (CRP) response and so may have the potential to modulate hepatic injury. • An elevated CRP concentration during the first postnatal week may be regarded as an expected finding in moderate and severe HIE and, in the overwhelming majority of cases, occurs secondary to hepatic hypoxia-ischemia in the absence of blood culture-positive sepsis.

Oxidative stress and endoplasmic reticulum (ER) stress in the development of neonatal hypoxic-ischaemic brain injury

Birth asphyxia in term neonates affects 1–2/1000 live births and results in the development of hypoxic–ischaemic encephalopathy with devastating life-long consequences. The majority of neuronal cell death occurs with a delay, providing the potential of a treatment window within which to act. Currently, treatment options are limited to therapeutic hypothermia which is not universally successful. To identify new interventions, we need to understand the molecular mechanisms underlying the injury. Here, we provide an overview of the contribution of both oxidative stress and endoplasmic reticulum stress in the development of neonatal brain injury and identify current preclinical therapeutic strategies.

Therapeutic hypothermia for ischemic stroke; pathophysiology and future promise

Therapeutic hypothermia, or cooling of the body or brain for the purposes of preserving organ viability, is one of the most robust neuroprotectants at both the preclinical and clinical levels. Although therapeutic hypothermia has been shown to improve outcome from related clinical conditions, the significance in ischemic stroke is still under investigation. Numerous pre-clinical studies of therapeutic hypothermia has suggested optimal cooling conditions, such as depth, duration, and temporal therapeutic window for effective neuroprotection. Several studies have also explored mechanisms underlying the mechanisms of neuroprotection by therapeutic hypothermia. As such, it appears that cooling affects multiple aspects of brain pathophysiology, and regulates almost every pathway involved in the evolution of ischemic stroke. This multifaceted mechanism is thought to contribute to its strong neuroprotective effect. In order to carry out this therapy in optimal clinical settings, methodological and pathophysiological understanding is crucial. However, more investigation is still needed to better understand the underlying mechanisms of this intervention, and to overcome clinical barriers which seem to preclude the routine use therapeutic hypothermia in stroke. This article is part of the Special Issue entitled 'Cerebral Ischemia'.

Maternal obesity increases inflammation and exacerbates damage following neonatal hypoxic-ischaemic brain injury in rats

OBJECTIVE

In humans, maternal obesity is associated with an increase in the incidence of birth related difficulties. However, the impact of maternal obesity on the severity of brain injury in offspring is not known. Recent studies have found evidence of increased glial response and inflammatory mediators in the brains as a result of obesity in humans and rodents. We hypothesised that hypoxic-ischaemic (HI) brain injury is greater in neonatal offspring from obese rat mothers compared to lean controls.

METHODS

Female Sprague Dawley rats were randomly allocated to high fat (HFD, n=8) or chow (n=4) diet and mated with lean male rats. On postnatal day 7 (P7), male and female pups were randomly assigned to HI injury or control (C) groups. HI injury was induced by occlusion of the right carotid artery followed by 3h exposure to 8% oxygen, at 37°C. Control pups were removed from the mother for the same duration under ambient conditions. Righting behaviour was measured on day 1 and 7 following HI. The extent of brain injury was quantified in brain sections from P14 pups using cresyl violet staining and the difference in volume between brain hemispheres was measured.

RESULTS

Before mating, HFD mothers were 11% heavier than Chow mothers (p<0.05, t-test). Righting reflex was delayed in offspring from HFD-fed mothers compared to the Chow mothers. The Chow-HI pups showed a loss in ipsilateral brain tissue, while the HFD-HI group had significantly greater loss. No significant difference was detected in brain volume between the HFD-C and Chow-C pups. When analysed on a per litter basis, the size of the injury was significantly correlated with maternal weight. Similar observations were made with neuronal staining showing a greater loss of neurons in the brain of offspring from HFD-mothers following HI compared to Chow. Astrocytes appeared to more hypertrophic and a greater number of microglia were present in the injured hemisphere in offspring from mothers on HFD. HI caused an increase in the proportion of amoeboid microglia and exposure to maternal HFD exacerbated this response. In the contralateral hemisphere, offspring exposed to maternal HFD displayed a reduced proportion of ramified microglia.

CONCLUSIONS

Our data clearly demonstrate that maternal obesity can exacerbate the severity of brain damage caused by HI in neonatal offspring. Given that previous studies have shown enhanced inflammatory responses in offspring of obese mothers, these factors including gliosis and microglial infiltration are likely to contribute to enhanced brain injury.

Neonatal hypoxic ischemic encephalopathy: an update on disease pathogenesis and treatment

INTRODUCTION

Hypoxic ischemic encephalopathy (HIE) is the most important reason for morbidity and mortality in term-born infants. Understanding pathophysiology of the brain damage is essential for the early detection of patients with high risk for HIE and development of strategies for their treatments. Areas covered: This review discusses pathophysiology of the neonatal HIE and its treatment options, including hypothermia, melatonin, allopurinol, topiramate, erythropoietin, N-acetylcyctein, magnesium sulphate and xenon. Expert commentary: Several clinical studies have been performed in order to decrease the risk of brain injury due to difficulties in the early diagnosis and treatment, and to develop strategies for better long-term outcomes. Although currently standard treatment methods include therapeutic hypothermia for neonates with moderate to severe HIE, new supportive options are needed to enhance neuroprotective effects of the hypothermia, which should aim to reduce production of the free radicals and to have anti-inflammatory and anti-apoptotic actions.

Therapeutic hypothermia for stroke: Where to go?

Ischemic stroke is a major cause of death and long-term disability worldwide. Thrombolysis with recombinant tissue plasminogen activator is the only proven and effective treatment for acute ischemic stroke; however, therapeutic hypothermia is increasingly recognized as having a tissue-protective function and positively influencing neurological outcome, especially in cases of ischemia caused by cardiac arrest or hypoxic-ischemic encephalopathy in newborns. Yet, many aspects of hypothermia as a treatment for ischemic stroke remain unknown. Large-scale studies examining the effects of hypothermia on stroke are currently underway. This review discusses the mechanisms underlying the effect of hypothermia, as well as trends in hypothermia induction methods, methods for achieving optimal protection, side effects, and therapeutic strategies combining hypothermia with other neuroprotective treatments. Finally, outstanding issues that must be addressed before hypothermia treatment is implemented at a clinical level are also presented.

Pathophysiology and neuroprotection of global and focal perinatal brain injury: lessons from animal models

BACKGROUND

Arterial ischemic stroke occurs more frequently in term newborns than in the elderly, and brain immaturity affects mechanisms of ischemic injury and recovery. The susceptibility to injury of the brain was assumed to be lower in the perinatal period as compared with childhood. This concept was recently challenged by clinical studies showing marked motor disabilities after stroke in neonates, with the severity of motor and cortical sensory deficits similar in both perinatal and childhood ischemic stroke. Our understanding of the triggers and the pathophysiological mechanisms of perinatal stroke has greatly improved in recent years, but many factors remain incompletely understood.

METHODS

In this review, we focus on the pathophysiology of perinatal stroke and on therapeutic strategies that can protect the immature brain from the consequences of stroke by targeting inflammation and brain microenvironment.

RESULTS

Studies in neonatal rodent models of cerebral ischemia have suggested a potential role for soluble inflammatory molecules as important modulators of injury and recovery. A great effort is underway to investigate neuroprotective molecules based on our increasing understanding of the pathophysiology.

CONCLUSION

In this review, we provide a comprehensive summary of new insights concerning pathophysiology of focal and global perinatal brain injury and their implications for new therapeutic approaches.

Mechanisms of hypothermia-induced cell protection in the brain

Therapeutic hypothermia is an effective cytoprotectant and promising intervention shown to improve outcome in patients following cardiac arrest and neonatal hypoxia-ischemia. However, despite our clinical and experimental experiences, the protective molecular mechanisms of therapeutic hypothermia remain to be elucidated. Therefore, in this brief overview we discuss both the clinical evidence and molecular mechanisms of therapeutic hypothermia in order to provide further insights into this promising intervention.

Therapeutic hypothermia delays the C-reactive protein response and suppresses white blood cell and platelet count in infants with neonatal encephalopathy

BACKGROUND

Therapeutic hypothermia (HT) delays the cytokine response in infants with neonatal encephalopathy (NE).

OBJECTIVE

To determine if HT delayed the C-reactive protein (CRP) response and altered white blood cell (WBC), neutrophil and platelet count course during the first week of life in infants with NE.

DESIGN

Retrospective cohort study.

SETTING

Regional neonatal intensive care unit, UK.

PATIENTS

104 term infants with NE (38 normothermia (NT) and 66 HT) born between 1998 and 2010. Infants not exposed to prenatal sepsis risk factors were classified as group 'A' and exposed infants to group 'B'. CRP >10 mg/L was defined as significant response.

MAIN OUTCOME MEASURES

Time to CRP >10 mg/L, peak CRP, WBC, neutrophil and platelet count.

RESULTS

Blood cultures were negative in all the infants. In babies who had CRP response, HT delayed time to CRP >10 mg/L (median (95% CI): group A, HT: 36 h (28.3 to 48.0); NT: 24 h (0.0 to 24.0); p=0.001; group B, HT: 30 h (15.2 to 56.8); NT: 12 h (0.0 to 24.0); p=0.009) and time to peak CRP (median (95% CI): group A, HT: 60 h (60.0 to 72.0); NT: 36 h (0.0 to 48.0); p=0.001; group B, HT: 84 h (62.1 to 120.0); NT: 24 h (0.0 to 36.0); p=0.001). Compared with NT, HT was associated with reduction in slope of CRP elevation by 0.5 (95% CI 0.04 to 0.97), WBC by 2.18×10(9)/L (95% CI 0.002 to 4.35) and platelet count by 32.3×10(9)/L (95% CI 2.75 to 61.8) independent of exposure to sepsis risk, meconium aspiration and severity of asphyxia.

CONCLUSIONS

Therapeutic hypothermia delayed the initiation of CRP and its peak response, and depressed the WBC and platelet count compared with NT.

Mechanisms of perinatal arterial ischemic stroke

The incidence of perinatal stroke is high, similar to that in the elderly, and produces a significant morbidity and severe long-term neurologic and cognitive deficits, including cerebral palsy, epilepsy, neuropsychological impairments, and behavioral disorders. Emerging clinical data and data from experimental models of cerebral ischemia in neonatal rodents have shown that the pathophysiology of perinatal brain damage is multifactorial. These studies have revealed that, far from just being a smaller version of the adult brain, the neonatal brain is unique with a very particular and age-dependent responsiveness to hypoxia-ischemia and focal arterial stroke. In this review, we discuss fundamental clinical aspects of perinatal stroke as well as some of the most recent and relevant findings regarding the susceptibility of specific brain cell populations to injury, the dynamics and the mechanisms of neuronal cell death in injured neonates, the responses of neonatal blood-brain barrier to stroke in relation to systemic and local inflammation, and the long-term effects of stroke on angiogenesis and neurogenesis. Finally, we address translational strategies currently being considered for neonatal stroke as well as treatments that might effectively enhance repair later after injury.

Effect of therapeutic hypothermia on DNA damage and neurodevelopmental outcome among term neonates with perinatal asphyxia: a randomized controlled trial

OBJECTIVE

To study the effect of therapeutic hypothermia (TH) on deoxyribonucleic acid (DNA) damage and the neurodevelopmental outcome in term babies with perinatal asphyxia.

METHODS

Babies in the hypothermia group were cooled for the first 72 h, using gel packs. Rectal temperature of 33-34°C was maintained. Blood sample was collected before, at 36 h and after completion of TH for assessment of comet assay and 8-hydroxy2-deoxyguanosine (8-OHdG). Infants were followed up till 12 months.

RESULTS

Baseline parameters were similar. After 72 h, the hypothermia group showed lower olive tail moment (12.88 ± 2.14) than the control group (22.16 ± 5.26) (p < 0.001). 8-HDG levels increased significantly in the control group (1252.87 ± 357.07) as compared to the hypothermia group (757.03 ± 198.49) (p < 0.001). Neurodevelopmental assessment at 12 months showed significantly low motor and mental developmental quotient in the control than hypothermia group.

CONCLUSIONS

TH reduces oxidative stress-induced DNA damage and improves neurodevelopmental outcome. <Trial registration No: CTRI/2011/10/002094>

Hesperidin pretreatment protects hypoxia-ischemic brain injury in neonatal rat

Neonatal hypoxia-ischemic encephalopathy (HIE) remains a major cause of brain damage, leading to high disability and mortality rates in neonates. In vitro studies have shown that hesperidin, a flavanone glycoside found abundantly in citrus fruits, acts as an antioxidant. Although hesperidin has been considered as a potential treatment for HIE, its effects have not been fully evaluated. In this study, the protective effect of hesperidin pretreatment against hypoxia-ischemic (HI) brain injury and possible signal pathways were investigated using in vivo and in vitro models. In vivo HI model employed unilateral carotid ligation in postnatal day 7 rat with exposure to 8% hypoxia for 2.5h, whereas in vitro model employed primary cortical neurons of neonatal rats subjected to oxygen and glucose deprivation for 2.5h. Hesperidin pretreatment significantly reduced HI-induced brain tissue loss and improved neurological outcomes as shown in 2,3,5-triphenyltetrazolium chloride monohydrate staining and foot-fault results. The neuroprotective effects of hesperidin are likely the results of preventing an increase in intracellular reactive oxygen species and lipid peroxide levels. Hesperidin treatment also activated a key survival signaling kinase, Akt, and suppressed the P-FoxO3 level. Hesperidin pretreatment protected neonatal HIE by reducing free radicals and activating phosphorylated Akt.

Effect of therapeutic hypothermia on oxidative stress and outcome in term neonates with perinatal asphyxia: a randomized controlled trial

OBJECTIVES

To evaluate in term babies with perinatal asphyxia, the effect of therapeutic hypothermia (TH) on oxidative stress and neurological outcome at discharge.

METHODS

Babies who satisfied inclusion criteria were randomized to TH, with cooling gel packs to a target temperature of 33-34°C for 72 h or normothermia. Blood sample was collected before and after TH for oxidative stress assessment: total antioxidant status (TAS) and malondialdehyde (MDA).

RESULTS

Of 116 babies randomized, there was no statistically significant difference in the baseline TAS and MDA. After 72 h of TH, TAS was significantly higher (p = <0.001) (761.69 ± 114.01 vs. 684.16 ± 88.86) and MDA was significantly lower (p = <0.001) in TH group (1.73 ± 0.66 vs. 5.2 ± 1.06). Risk of developing deficit was lower (p < 0.001) in TH group with relative risk of 0.49 and 95 % confidence interval: 0.29-0.68.

CONCLUSION

TH reduces oxidative stress and improves neurological outcome in perinatal asphyxia.

TRIAL REGISTRATION NUMBER

CTRI/2011/12/002196.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal studies and pilot studies in humans suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae without adverse effects.

OBJECTIVES

To determine the effect of therapeutic hypothermia in encephalopathic asphyxiated newborn infants on mortality, long-term neurodevelopmental disability and clinically important side effects.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group as outlined in The Cochrane Library (Issue 2, 2007). Randomised controlled trials evaluating therapeutic hypothermia in term and late preterm newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, 2007, Issue 2), MEDLINE (1966 to June 2007), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal handsearching. We updated this search in May 2012.

SELECTION CRITERIA

We included randomised controlled trials comparing the use of therapeutic hypothermia with standard care in encephalopathic term or late preterm infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Four review authors independently selected, assessed the quality of and extracted data from the included studies. Study authors were contacted for further information. Meta-analyses were performed using risk ratios (RR) and risk differences (RD) for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals (CI).

MAIN RESULTS

We included 11 randomised controlled trials in this updated review, comprising 1505 term and late preterm infants with moderate/severe encephalopathy and evidence of intrapartum asphyxia. Therapeutic hypothermia resulted in a statistically significant and clinically important reduction in the combined outcome of mortality or major neurodevelopmental disability to 18 months of age (typical RR 0.75 (95% CI 0.68 to 0.83); typical RD -0.15, 95% CI -0.20 to -0.10); number needed to treat for an additional beneficial outcome (NNTB) 7 (95% CI 5 to 10) (8 studies, 1344 infants). Cooling also resulted in statistically significant reductions in mortality (typical RR 0.75 (95% CI 0.64 to 0.88), typical RD -0.09 (95% CI -0.13 to -0.04); NNTB 11 (95% CI 8 to 25) (11 studies, 1468 infants) and in neurodevelopmental disability in survivors (typical RR 0.77 (95% CI 0.63 to 0.94), typical RD -0.13 (95% CI -0.19 to -0.07); NNTB 8 (95% CI 5 to 14) (8 studies, 917 infants). Some adverse effects of hypothermia included an increase sinus bradycardia and a significant increase in thrombocytopenia.

AUTHORS' CONCLUSIONS

There is evidence from the 11 randomised controlled trials included in this systematic review (N = 1505 infants) that therapeutic hypothermia is beneficial in term and late preterm newborns with hypoxic ischaemic encephalopathy. Cooling reduces mortality without increasing major disability in survivors. The benefits of cooling on survival and neurodevelopment outweigh the short-term adverse effects. Hypothermia should be instituted in term and late preterm infants with moderate-to-severe hypoxic ischaemic encephalopathy if identified before six hours of age. Further trials to determine the appropriate techniques of cooling, including refinement of patient selection, duration of cooling and method of providing therapeutic hypothermia, will refine our understanding of this intervention.

Pathophysiological role of inflammatory molecules in paediatric ischaemic brain injury

Ischaemic stroke is one of the major causes of death and lifelong disability also in the paediatric population. Strong scientific effort has been put to clarify the pathophysiology of this disease in adults. However, only few studies have been performed in children. Preliminary results indicate that pathophysiological processes might differently affect the poststroke neuronal injury in neonates as compared to children. During the neural development, selective molecular mechanisms might be differently triggered by an ischaemic insult, thus potentially resulting in defined postischaemic clinical outcomes. Basic research studies in neonatal animal models of cerebral ischaemia have recently shown a potential role of soluble inflammatory molecules (such as cytokines, chemokines and oxidants) as pivotal players of neuronal injury in both perinatal and childhood ischaemic stroke. Although larger clinical trials are still needed to confirm these preliminary results, the potential benefits of selective treatments targeting inflammation in perinatal asphyxia encephalopathy might represent a promising investigation field in the near future. In this review, we will update evidence on the pathophysiological role of soluble inflammatory mediators in neonatal and childhood ischaemic stroke. Recent evidence on potential anti-inflammatory treatments to improve paediatric stroke prognosis will be discussed.

Effect of short-term cryostimulation on antioxidative status and its clinical applications in humans

Whole body cryostimulation (WBCT) is becoming popular in medicine and sport as an adjuvant form of treatment since late 1970s. Only a few works concerning antioxidant protection after WBCT have been published. The aim of this study was to determine the effect of a ten 3-min-long exposures (one exposure per day) to cryogenic temperature (-130 °C) on the level of total antioxidant status (TAS), activity of selected antioxidant enzyme superoxide dismutase (SOD) and main non-enzymatic antioxidant-uric acid (UA) in WBCT study group (man n = 24; female n = 22) and non-WBCT control subjects (man n = 22; female n = 26). Moreover, we evaluated the lipid peroxidation measured as thiobarbituric acid reactive substances products. Their blood samples were collected twice at an interval of 10 days in both study group and control subjects. The activity of antioxidant enzyme and lipid peroxidation was assayed in erythrocytes, while the concentration of uric acid was measured in plasma. After completing a total of ten WBCT sessions a significant increase (p < 0.001) of TAS and UA levels in plasma (p < 0.001) in comparison to non-WBCT was observed. Our data showed that there was statistically significant increase of the activities of SOD in erythrocytes obtained from WBCT study group compared to non-WBCT controls after 10 days of treatment (p < 0.001). It was concluded that expositions to extremely low temperatures use in cryostimulation improve the antioxidant capacity of organism.

Hypothermia attenuates the severity of oxidative stress development in asphyxiated newborns

PURPOSE

This retrospective case-control study aimed to examine the development of oxidative stress in asphyxiated infants delivered at more than 37 weeks of gestation.

MATERIAL AND METHODS

Thirty-seven neonates were stratified into 3 groups: the first group experienced hypothermia (n = 6); the second received hypothermia cooling cup treatment for 3 days, normothermia (n = 16); and the third was the control group (n = 15). Serum total hydroperoxide (TH), biological antioxidant potential, and oxidative stress index (OSI) (calculated as TH/biological antioxidant potential) were measured within 3 hours after birth.

RESULTS

Serum TH and OSI levels gradually increased after birth in hypothermia and normothermia cases. At all time points, serum TH and OSI levels were higher in hypothermia and normothermia cases than in control cases. Serum TH and OSI levels were higher in normothermia cases than in hypothermia cases at days 3, 5, and 7.

CONCLUSION

This study demonstrated that hypothermia attenuated the development of systemic oxidative stress in asphyxiated newborns.

Cooling for newborns with hypoxic ischaemic encephalopathy

BACKGROUND

Newborn animal and human pilot studies suggest that mild hypothermia following peripartum hypoxia-ischaemia in newborn infants may reduce neurological sequelae, without adverse effects.

OBJECTIVES

To determine whether therapeutic hypothermia in encephalopathic asphyxiated newborn infants reduces mortality and long-term neurodevelopmental disability, without clinically important side effects.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group as outlined in the Cochrane Library (Issue 2, 2003) was used. Randomised controlled trials evaluating therapeutic hypothermia in term newborns with hypoxic ischaemic encephalopathy were identified by searching the Oxford Database of Perinatal Trials, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue Issue 2, 2003), MEDLINE (1966 to July 2003), previous reviews including cross-references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching.

SELECTION CRITERIA

Randomised controlled trials comparing the use of therapeutic hypothermia with normothermia in encephalopathic newborn infants with evidence of peripartum asphyxia and without recognisable major congenital anomalies were included. The primary outcome measure was death or long-term major neurodevelopmental disability. Other outcomes included adverse effects of cooling and 'early' indicators of neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

Three reviewers independently selected, assessed the quality of and extracted data from the included studies. Authors were contacted for further information. Meta-analyses were performed using relative risk and risk difference for dichotomous data, and weighted mean difference for continuous data with 95% confidence intervals.

MAIN RESULTS

Two randomised controlled trials were included in this review, comprising 50 term infants with moderate/ severe encephalopathy and evidence of intrapartum asphyxia. There was no significant effect of therapeutic hypothermia on the combined outcome of death or major neurodevelopmental disability in survivors followed. No adverse effects of hypothermia on short term medical outcomes or on some 'early' indicators of neurodevelopmental outcome were detected.

REVIEWER'S CONCLUSIONS

Although two small randomised controlled trials demonstrated neither evidence of benefit or harm, current evidence is inadequate to assess either safety or efficacy of therapeutic hypothermia in newborn infants with hypoxic ischaemic encephalopathy. Therapeutic hypothermia for encephalopathic asphyxiated newborn infants should be further evaluated in well designed randomised controlled trials.