Modulation of nuclear factor-kappaB activation and decreased markers of neurological injury associated with hypothermic therapy in experimental bacterial meningitis

Therapeutic hyperthermia for the treatment of infection-a narrative review

Modulating body temperature, mostly through the use of antipyretics, is a commonly employed therapeutic intervention in medical practice. However, emerging evidence suggests that hyperthermia could serve as an adjuvant therapy for patients with infection. We performed a narrative review to explore the application of therapeutic hyperthermia in the treatment of infection. A number of studies have been performed in the pre-antibiotic era, enrolling patients with neurosyphilis and gonococcal infections, with reported cure rates at around 60%-80%. We have outlined the potential molecular and immunological mechanisms explaining the possible beneficial effects of therapeutic hyperthermia. For some pathogens increased temperature exerts a direct negative effect on virulence; however, it is presumed that temperature driven activation of the immune system is probably the most important factor affecting microbial viability. Lastly, we performed a review of modern-era studies where modulation of body temperature has been used as a treatment strategy. In trials of therapeutic hypothermia in patients with infection worse outcomes have been observed in the hypothermia group. Use of antipyretics has not been associated with any improvement in clinical outcomes. In modern-era therapeutic hyperthermia achieved by physical warming has been studied in one pilot trial, and better survival was observed in the hyperthermia group. To conclude, currently there is not enough data to support the use of therapeutic hyperthermia outside clinical trials; however, available studies are in favor of at least a temperature tolerance strategy for non-neurocritical patients.

Therapeutic Hypothermia in Critically Ill Patients: A Systematic Review and Meta-Analysis of High Quality Randomized Trials

OBJECTIVES

To investigate the effect of the application of therapeutic hypothermia (32-35°C) on survival and major clinical endpoints in critically ill patients.

DATA SOURCES

We searched online database and clinical trial registries dated up to April 30, 2019, and references of relevant studies.

STUDY SELECTION

Low risk of bias randomized trials which compared hypothermia applied for at least 24 hours and conventional therapy in critically ill patients were included. We excluded trials investigating therapeutic hypothermia in indications already supported by international guidelines (adult cardiac arrest and hypoxic-ischemic encephalopathy of newborns) or intraoperative hypothermia.

DATA EXTRACTION

Titles and abstracts were reviewed independently by two authors. If the articles seemed eligible, full-text articles were reviewed, and data were abstracted using a structured template.

DATA SYNTHESIS

Our search retained 14 low risk of bias randomized trials (2,670 patients) performed in three different settings: traumatic brain injury, serious infections, and stroke. Therapeutic hypothermia was associated with an increase in mortality at longest follow-up available (432/1,375 [31%] vs 330/1,295 [25%]; risk ratio, 1.24; 95% CI, 1.10-1.39; p = 0.0004; I = 0%). Pooled results showed no difference of good neurologic outcome among survivors between the two treatment arms (493/1,142 [43%] vs 486/1,067 [46%]; risk ratio, 1.04; 95% CI, 0.97-1.12; p = 0.27; I = 1%). Arrhythmias were significantly increased among patients undergoing therapeutic hypothermia. We found no difference between groups in pneumonia, serious infections, any infection, hemorrhage, renal failure, deep vein thrombosis, and uncontrollable intracranial hypertension.

CONCLUSIONS

High-quality randomized evidence indicates that therapeutic hypothermia is associated with higher mortality and no difference in good neurologic outcome compared with normothermia in critically ill patients. Although there still might be a possibility that therapeutic hypothermia is beneficial in a specific setting, routine application of therapeutic hypothermia would better be avoided outside the settings indicated by international guidelines (adult cardiac arrest and hypoxic-ischemic encephalopathy of newborns).

Invasive neuromonitoring and neurological intensive care unit management in life-threatening central nervous system infections

PURPOSE OF REVIEW

Patients with infectious diseases of the central nervous system (CNS) commonly require treatment in the intensive care unit (ICU). In a subset of patients with a life-threatening course, a more aggressive and invasive management is required. Treatment relies on the expertise of the intensivists as most recommendations are currently not based on a high level of evidence.

RECENT FINDINGS

Published data suggest that an invasive brain-focused management should be considered in life-threatening CNS infections. Brain resuscitation by adequate control of intracranial pressure (ICP) and optimization of cerebral perfusion, oxygen and glucose delivery supports the idea of personalized medicine. Recent advances in monitoring techniques help to guide clinicians to improve neurocritical care management in these patients with severe disease. Robust data on the long-term effect of decompressive craniectomy and targeted temperature management are lacking, however, these interventions can be life-saving in individual patients in the setting of a potentially fatal situation such as refractory elevated ICP.

SUMMARY

Advances in the neurocritical care management and progress in monitoring techniques in specialized neuro-ICUs may help to preserve brain function and prevent a deleterious cascade of secondary brain damage in life-threatening CNS infections.

Increased cerebrospinal fluid cleaved tau protein (C-tau) levels suggest axonal damage in pediatric patients with brain tumors

OBJECTIVE

This study aims to determine if cerebrospinal fluid/serum cleaved tau protein and CSF 9-hydroxyoctadecadienoic acid levels, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in brain tumor patients compared with controls.

DESIGN

This article is a prospective clinical observational study.

SETTING

This study is conducted at a tertiary-care children's hospital.

PATIENTS

Our participants are children younger than or equal to 18 years of age undergoing brain tumor surgery.

MEASUREMENTS AND MAIN RESULTS

During the study period, 26 consecutive patients newly diagnosed with brain tumors who met the inclusion criteria were prospectively enrolled. Baseline cerebrospinal fluid analysis of cleaved tau and 9-hydroxyoctadecadienoic acid were measured in 15 patients. Cerebrospinal fluid cleaved tau and 9-hydroxyoctadecadienoic acid levels were measured in 22 patients for post-surgery days 1 and 3. Serum cleaved tau levels were measured for 20 and 18 patients for post-surgery days 1 and 3, respectively. The presence of a brain tumor significantly increased the baseline cerebrospinal fluid cleaved tau levels but did not affect cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. Similarly, there was a significant increase in post-surgery day 1 cerebrospinal fluid cleaved tau levels from baseline (p = 0.01) and a trend toward significant decrease in post-surgery day 3 cerebrospinal fluid cleaved tau from day 1 (p = 0.07). 9-Hydroxyoctadecadienoic acid concentrations remained relatively constant over time with no differences noted between the control and brain tumor patients. There was a trend towards a significant association between cerebrospinal fluid cleaved tau levels and duration of symptoms (p = 0.07).

CONCLUSIONS

Cerebrospinal fluid cleaved tau levels in children with newly diagnosed brain tumors exhibit markedly elevated cerebrospinal fluid cleaved tau levels, suggesting axonal damage. This axonal injury does not seem to correlate with lipid peroxidation at least when as assessed by cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. There was no association found between the biomarkers and multiple independent variables obtained at pre- and post-tumor resection.

Association between Experimental Bacterial Meningitis and Periapical Lesion

INTRODUCTION

Mortality and morbidity from bacterial meningitis in African adults is significantly higher than those in better resourced settings. At the same time, the periodontal diseases are highly prevalent and can affect up to 90% of the population. Dental caries in Uganda was recorded in 40% and 62.5% of the children and adults, respectively. We hypothesize that pneumococcal meningitis could interfere in the development of periapical lesion. The aim of this study was to evaluate periapical lesion in Wistar rats subjected to pneumococcal meningitis.

MATERIALS AND METHODS

The animals were divided in control, control/periapical lesion, meningitis, and meningitis/periapical lesion groups. The surgical exposure of molars and the infection of the dental pulp were from the oral environment. Pulp necrosis was induced on the left mandibular first molars during adulthood. Dental pulps were exposed by drilling cavities on the central portion of the occlusal surface with a 1011 HL round bur in high speed to a depth nearly equal to the bur diameter. Animals were subjected to behavioral task and evaluation of the size of periodontal ligament. Data from periodontal ligament space and open field task were reported as mean ± SEM and analysed by Two-way ANOVA and paired Student's t-test, respectively.

RESULTS AND CONCLUSION

Meningitis/periapical increased the periodontal ligament space by 61% when compared with control/periapical. In the open-field task, there were no differences in the number of crossings and rearing movements between training and test session in meningitis and periapical lesion groups demonstrating habituation memory impairment. Bacterial meningitis and periapical lesion may play an important role in development of cognitive impairment.

Erythropoietin prevents cognitive impairment and oxidative parameters in Wistar rats subjected to pneumococcal meningitis

Pneumococcal meningitis is characterized by a severe inflammatory reaction in the subarachnoid and ventricular space of the brain, disruption of the blood-brain barrier, hearing loss, and neurologic sequelae in as many as 27% of surviving patients. Several experimental studies have shown that erythropoietin (EPO) and its receptor are expressed in the central nervous system and have neuroprotective properties through the inhibition of apoptosis, as well as anti-inflammatory, antioxidant, angiogenic, and neurotrophic effects. In the current study, we demonstrated the effect of erythropoietin (EPO) on lipid peroxidation, protein carbonylation, superoxide dismutase (SOD), catalase (CAT), myeloperoxidase (MPO), and behavioral parameters in rats with pneumococcal meningitis. EPO decreased lipid peroxidation and protein carbonylation, and it prevented protein degradation in the hippocampus and frontal cortex. MPO activity was decreased, and both SOD and CAT activity were increased in the first 6 hours after pneumococcal meningitis induction. Novel object recognition memory was impaired in the meningitis group; however, adjuvant treatment with EPO prevented memory impairment during both the short- and long-term retention tests. The meningitis group showed no difference in motor and exploratory activity between training and test sessions in the open-field task, which indicates that habituation memory was impaired; however, adjuvant treatment with EPO prevented habituation memory impairment. Although there are some limitations with respect to the animal model of pneumococcal meningitis, this study suggests that adjuvant treatment with EPO contributed to decreased oxidative stress and prevented cognitive impairment.

Inhibition of matrix metalloproteinases-2 and -9 prevents cognitive impairment induced by pneumococcal meningitis in Wistar rats

Pneumococcal meningitis is a relevant clinical disease characterized by an intense inflammatory reaction into the subarachnoid and ventricular spaces, leading to blood–brain barrier breakdown, hearing loss, and cognitive impairment. Matrix metalloproteinases (MMPs) are capable of degrading components of the basal laminin, thus contributing to BBB damage and neuronal injury. In the present study, we evaluated the effects of MMP-2, MMP-9, and MMP-2/9 inhibitors on BBB integrity, learning, and memory in Wistar rats subjected to pneumococcal meningitis. The animals underwent a magna cistern tap and received either 10 µL sterile saline as a placebo or an equivalent volume of a Streptococcus pneumoniae suspension at a concentration of 5 × 109 cfu/mL. The rats were randomized into different groups that received adjuvant treatment with MMP-2, MMP-9 or MMP-2/9 inhibitors. The BBB integrity was evaluated, and the animals were habituated to open-field and object recognition tasks 10 days after meningitis induction. Adjuvant treatments with inhibitors of MMP-2 or MMP-2/9 prevented BBB breakdown in the hippocampus, and treatments with inhibitors of MMP-2, MMP-9 or MMP-2/9 prevented BBB breakdown in the cortex. Ten days after meningitis induction, the animals that received adjuvant treatment with the inhibitor of MMP-2/9 demonstrated that animals habituated to the open-field task faster and enhanced memory during short-term and long-term retention test sessions in the object recognition task. Further investigation is necessary to provide support for MMP inhibitors as an alternative treatment for bacterial meningitis; however, these findings suggest that the meningitis model could be a good research tool for studying the biological mechanisms involved in the behavioral alterations associated with pneumococcal meningitis.

Klebsiella pneumoniae meningitis induces memory impairment and increases pro-inflammatory host response in the central nervous system of Wistar rats

Klebsiella pneumoniae meningitis has recently become an increasingly common cause of central nervous system infection. The invasion of bacteria within the subarachnoid space stimulates the release of pro-inflammatory cytokines and chemokines, triggering a host immune response. The aim of the present study was to evaluate memory and pro-inflammatory mediators at different times in the brains of adult Wistar rats with K. pneumoniae meningitis. The animals were sacrificed at 6, 12, 24, 48 and 96 h after meningitis induction. The hippocampus, frontal cortex and cerebrospinal fluid were isolated to determine the cytokine, chemokine and brain-derived neurotrophic factor (BDNF) levels. In the first 6 and 24 h following meningitis induction, there was a significant increase of the TNF-α, IL-1β, IL-6, cytokine-induced neutrophil chemoattractant-1 and BDNF levels in the central nervous system. Ten days after meningitis induction, cognitive memory was evaluated using an open-field task and step-down inhibitory avoidance task. In the control group, significant differences in behaviour were observed between the training and testing sessions for both tasks, demonstrating habituation and aversive memory. However, the meningitis group did not exhibit any difference between the training and testing sessions in either task, demonstrating memory impairment. As a result of these observations, we believe that the meningitis model may be a good research tool to study the biological mechanisms involved in the pathophysiology of this illness, while recognizing that animal models should be interpreted with caution before extrapolation to the clinic.

Bacterial meningitis: new therapeutic approaches

Bacterial meningitis remains a disease with high mortality and long-term morbidity. Outcome critically depends on the rapid initiation of effective antibiotic therapy. Since a further increase of the incidence of pathogens resistant to antibacterials can be expected both in community-acquired and nosocomial bacterial meningitis, the choice of an optimum initial empirical antibiotic regimen will gain significance. In this context, the use of antibiotics which are bactericidal but do not lyse bacteria, may emerge as a therapeutic option. Conversely, the role of corticosteroids, which decrease the entry of hydrophilic antibacterials into the cerebrospinal fluid, as adjunctive therapy will probably decline as a consequence of the increasing antibiotic resistance of bacteria causing meningitis. Consequent vaccination of all children at present is the most efficient manner to reduce disease burden.

Attenuation of cognitive impairment by the nonbacteriolytic antibiotic daptomycin in Wistar rats submitted to pneumococcal meningitis

Background

Streptococcus pneumoniae is associated with neurologic sequels, such as, seizures, sensory-motor deficits, hearing loss, learning and memory impairment, which can occur in approximately 30 to 52% of surviving patients. Neuronal damage can be caused by intense inflammatory reaction and direct effects of the bacteria virulence factors. The aim of the present study was to evaluate the effects of the nonbacteriolytic antibiotic daptomycin versus ceftriaxone on behavioral parameters in adult Wistar rats submitted to pneumococcal meningitis.

Results

Ten days after induction we verified that the meningitis group with daptomycin treatment showed retention of aversive memory; it presented memory of the object recognition at short term and long term. In continuous multiple-trials step-down inhibitory avoidance task the meningitis group with ceftriaxone treatment required approximately two times more stimulus to reach the acquisition criterion when compared with meningitis group with daptomycin treatment. However, in the habituation memory test there were no differences in the number of crossings and rearings in training and task sessions demonstrating habituation impairment to the environment task in both meningitis groups.

Conclusions

The evidence of the present study shows the potential alternative of the treatment with daptomycin in preventing learning and memory impairments caused by pneumococcal meningitis. Further investigations are necessary to provide support for evaluation of daptomycin as an alternative treatment of bacterial meningitis.

Evaluation of energetic metabolism in the rat brain after meningitis induction by Klebsiella pneumoniae

BACKGROUND

Bacterial meningitis is an infection of the central nervous system characterised by strong inflammatory response. The brain is highly dependent on ATP, and the cell energy is obtained through oxidative phosphorylation, a process which requires the action of various respiratory enzyme complexes and creatine kinase (CK) as an effective buffering system of cellular ATP levels in tissues that consume high energy.

OBJECTIVES

Evaluate the activities of mitochondrial respiratory chain complexes I, II, III, IV and CK activity in hippocampus and cortex of the Wistar rat submitted to meningitis by Klebsiella pneumoniae.

METHODS

Adult Wistar rats received either 10 µl of sterile saline as a placebo or an equivalent volume of K. pneumoniae suspension. The animals were killed in different times at 6, 12, 24 and 48 h after meningitis induction. Another group was treated with antibiotic, starting at 16 h and continuing daily until their decapitation at 24 and 48 h after induction.

RESULTS

In the hippocampus, the meningitis group without antibiotic treatment, the complex I was increased at 24 and 48 h, complex II was increased at 48 h, complex III was inhibited at 6, 12, 24 and 48 h and in complex IV all groups with or without antibiotic treatment were inhibited after meningitis induction, in the cortex there was no alteration. Discussion Although descriptive, our results show that antibiotic prevented in part the changes of the mitochondrial respiratory chain. The meningitis model could be a good research tool to study the biological mechanisms involved in the pathophysiology of the K. pneumoniae meningitis.

Circulating concentrations, cerebral output of the CINC-1 and blood–brain barrier disruption in Wistar rats after pneumococcal meningitis induction

Pneumococcal meningitis is a severe infectious illness of the central nervous system (CNS), with high rates of lethality and morbidity, being that the microorganism and the host's inflammatory response are responsible for cerebral complications. Moreover, the blood–brain barrier (BBB) itself secretes cytokines and, because of the bipolar nature of the BBB, these substances can be secreted into either the CNS compartment or in the blood, so patients with acute bacterial meningitis frequently develop sepsis. Therefore, the aim of this study was to evaluate the cytokine/chemokine levels in different vessels and the BBB integrity after pneumococcal meningitis induction. Wistar rats were infected with Streptococcus pneumoniae, and the BBB integrity was investigated using Evan's blue dye. Also, blood from the carotid artery and jugular vein was collected in order to perform tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-60 and cytokine-induced neutrophil chemoattractant-1 (CINC-1) analyses by enzyme-linked immunosorbent assay (ELISA). CINC-1 levels were increased at 6 h in the arterial plasma and at 3 and 6 h in the jugular plasma. We observed BBB breakdown between 12 and 24 h in the hippocampus and at 12 and 18 h in the cortex after pneumococcal meningitis induction. The increase of CINC-1 occurred prior to the BBB breakdown. CINC-1 is a neutrophil chemoattractant and it may be related to early events in the pneumococcal meningitis pathophysiology.

Dexamethasone treatment reverses cognitive impairment but increases brain oxidative stress in rats submitted to pneumococcal meningitis

Pneumococcal meningitis is associated with a significant mortality rate and neurologic sequelae. The animals received either 10 μL of saline or a S. pneumoniae suspension and were randomized into different groups: sham: placebo with dexamethasone 0.7 mg/kg/1 day; placebo with dexamethasone 0.2 mg/kg/7 days; meningitis groups: dexamethasone 0.7 mg/kg/1 day and dexamethasone 0.2 mg/kg/7 days. Ten days after induction we evaluated memory and oxidative stress parameters in hippocampus and cortex. In the step-down inhibitory avoidance task, we observed memory impairment in the meningitis group with dexamethasone 0.2 mg/kg/7 days. The lipid peroxidation was increased in hippocampus in the meningitis groups with dexamethasone and in cortex only in the meningitis group with dexamethasone 0.2 mg/kg/7 days. The protein carbonyl was increased in hippocampus in the meningitis groups with dexamethasone and in cortex in the meningitis groups with and without dexamethasone. There was a decrease in the proteins integrity in hippocampus in all groups receiving treatment with dexamethasone and in cortex in all groups with dexamethasone (0.7 mg/kg/1 day). The mitochondrial superoxide was increased in the hippocampus and cortex in the meningitis group with dexamethasone 0.2 mg/kg/7 days. Our findings demonstrate that dexamethasone reverted cognitive impairment but increased brain oxidative stress in hippocampus and cortex in Wistar rats ten days after pneumococcal meningitis induction.

Evaluation of mitochondrial respiratory chain in the brain of rats after pneumococcal meningitis

The brain is highly dependent on ATP and most cell energy is obtained through oxidative phosphorylation, a process requiring the action of various respiratory enzyme complexes located in a special structure of the inner mitochondrial membrane. Bacterial meningitis due to Streptococcus pneumoniae is associated with a significant mortality rate and persisting neurologic sequelae including sensory-motor deficits, seizures, and impairments of learning and memory. In this context, we evaluated the activities of mitochondrial respiratory chain complexes in the brain of rats submitted to meningitis by S. pneumoniae inoculation into the cisterna magna. Our results demonstrated that complex I activity was not altered in cerebral cortex after meningitis; complexes II, III and IV were increased 24 and 48h after meningitis. We have also verified that complex I was inhibited in prefrontal cortex 48h after meningitis; complexes II, III and IV were not altered. Our results also demonstrated that complex I activity was inhibited in striatum, hippocampus and cerebellum 24h after meningitis. Moreover, complex II activity was increased in hippocampus and striatum 24 and 48h after meningitis; complexes III and IV activity were increased in striatum, hippocampus and cerebellum 48h after meningitis. Taking together previous reports and our present findings, we speculate that oxidative stress and metabolism impairment might contribute, at least in part, for the pathogenesis of pneumococcal meningitis.

Antibiotic therapy prevents, in part, the oxidative stress in the rat brain after meningitis induced by Streptococcus pneumoniae

Bacterial meningitis is associated with intense inflammation and also linked to the production of reactive oxygen species. To this aim, animals underwent a magna cistern tap and received either sterile saline as a placebo or an equivalent volume of a Streptococcus pneumoniae suspension. The animals began antibiotic therapy 16h after induction. The animals were sacrificed at 24 or 48h post-infection and the hippocampus and cortex were harvested. The activity of the enzymes superoxide dismutase, catalase, and thiobarbituric acid reactive species, protein carbonyls, and free sulphydryl groups were altered, but reversed, in part, by the antibiotic treatment. Our results support the hypothesis that antibiotic treatment prevents, in part, the oxidative stress in the bacterial meningitis induced by Streptococcus pneumoniae.

Depressive-like-behavior and proinflamatory interleukine levels in the brain of rats submitted to pneumococcal meningitis

Bacterial meningitis due to Streptococcus pneumoniae is associated with a significant mortality rate and persisting neurologic sequelae including sensorymotor deficits, seizures, and impairments of learning and memory. The presence of proliferating bacteria within the subarachnoid and ventricular space compartments triggers an intense inflammatory host response. Proinflammatory mediators released in the process include tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and all of which have been shown to contribute to the development of brain injury in bacterial meningitis. The animals underwent a magna cistern tap receiving either 10muL sterile saline as a placebo or an equivalent volume of a S. pneumoniae suspension at the concentration 5x10(9)cfu/mL. Ten days after induction we evaluated depressive-like behavior by using the forced swimming test and verified the levels of the TNF-alpha, IL-1beta, IL-6 and CINC-1 in the brain of rats induced to pneumococcal meningitis. In the forced swimming test we observed a significant increase in the immobility time in the meningitis group compared to the sham group (p<0.05). The TNFlevels were found increased in the prefrontal cortex (p<0.05, F=4.921), but not hippocampus. The IL-6, CINC-1 and IL-1beta levels presented no alteration in both prefrontal cortex and hippocampus 10 days after meningitis induction by S. pneumoniae. These findings suggest that the meningitis model could be a good research tool for the study of the biological mechanisms involved in the behavioral alterations secondary to pneumococcal meningitis.

Tumor necrosis factor alpha (TNF-alpha) levels in the brain and cerebrospinal fluid after meningitis induced by Streptococcus pneumoniae

Bacterial meningitis due to Streptococcus pneumoniae is associated with a significant mortality rate and persisting neurologic sequelae including sensory-motor deficits, seizures, and impairments of learning and memory. The presence of proliferating bacteria within the subarachnoid and ventricular space compartments triggers an intense inflammatory host response at killing the invading microorganism. Proinflammatory mediators released in the process include tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, IL-6. TNF-alpha have several effects, including cytotoxicity, antiviral activity, transcription factor activation, and immune response regulation. Thus, the aim of this study was to verify the levels of the TNF-alpha after pneumococcal meningitis in male Wistar rats. The animals underwent a magna cistern tap receiving either 10 microL sterile saline as a placebo or an equivalent volume of a S. pneumoniae suspension at the concentration 5 x 10(9)cfu/mL. The animals were killed at 0, 6, 12, 24, 48 and 96 h after induction. The brain was removed and hippocampus, cortex, prefrontal and cerebrospinal fluid (CSF) were isolated and used for the determination of TNF-alpha levels. We found an increase in TNF-alpha levels at 6h after induction of the meningitis in the hippocampus (p<0.01), frontal cortex (p<0.05), and cerebrospinal fluid (p<0.001).There was no alteration in the cortex. Our data suggest that TNF-alpha is involved in the pathophysiology of the pneumococcal meningitis and could be investigated as a putative biomarker for brain damage in the first hours.

Acute brain injury and therapeutic hypothermia in the PICU: A rehabilitation perspective

Acquired brain injury from traumatic brain injury, cardiac arrest (CA), stroke, and central nervous system infection is a leading cause of morbidity and mortality in the pediatric population and reason for admission to inpatient rehabilitation. Therapeutic hypothermia is the only intervention shown to have efficacy from bench to bedside in improving neurological outcome after birth asphyxia and adult arrhythmia-induced CA, thought to be due to its multiple mechanisms of action. Research to determine if therapeutic hypothermia should be applied to other causes of brain injury and how to best apply it is underway in children and adults. Changes in clinical practice in the hospitalized brain-injured child may have effects on rehabilitation referral practices, goals and strategies of therapies offered, and may increase the degree of complex medical problems seen in children referred to inpatient rehabilitation.

Hypothermia augments NF-kappaB activity and the production of IL-12 and IFN-gamma

BACKGROUND

The differentiation of Th1 and Th2 is strictly regulated by humoral and cellular factors. The imbalance between Th1 and Th2 is considered to be the pathogenesis of allergic and autoimmune disorders. It is important to elucidate the effect of environmental factors, such as temperature, on the expression of cytokines of Th1 and Th2.

METHODS

We investigated the expression of IFN-gamma, IL-4, IL-5, IL-10 and IL-12 from LPS- or PHA-stimulated PBMCs at 30 degrees C or 37 degrees C using ELISA and Real-time PCR. We measured the change of NF-kappaB activity at 30 degrees C or 37 degrees C with LPS stimulation using the reporter gene assay.

RESULTS

IFN-gamma production from LPS-stimulated PBMCs at 30 degrees C was up-regulated compared with 37 degrees C. IL-5 and IL-10 production from PHA-stimulated PBMCs at 30 degrees C were down-regulated compared with 37 degrees C. This augmented IFN-gamma production was caused by the up-regulation of IL-12 production from CD14+ blood monocytes. Both IL-12 mRNA and IL12 protein at 30 degrees C were up-regulated compared with 37 degrees C. NF-kappaB, the key molecule for the expression of IL-12, was also augmented at 30 degrees C compared with 37 degrees C.

CONCLUSIONS

Hypothermia up-regulated the expression of IL-12 and IFN-gamma due to the augmented NF-kappaB activity. It is suggested that hypothermia modifies the pattern of cytokine gene expression.

Inflammation and NFkappaB activation is decreased by hypothermia following global cerebral ischemia

We previously showed that hypothermia attenuates inflammation in focal cerebral ischemia (FCI) by suppressing activating kinases of nuclear factor-kappa B (NFkappaB). Here we characterize the inflammatory response in global cerebral ischemia (GCI), and the influence of mild hypothermia. Rodents were subjected to GCI by bilateral carotid artery occlusion. The inflammatory response was accompanied by microglial activation, but not neutrophil infiltration, or blood brain barrier disruption. Mild hypothermia reduced CA1 damage, decreased microglial activation and decreased nuclear NFkappaB translocation and activation. Similar anti-inflammatory effects of hypothermia were observed in a model of pure brain inflammation that does not cause brain cell death. Primary microglial cultures subjected to oxygen glucose deprivation (OGD) or stimulated with LPS under hypothermic conditions also experienced less activation and less NFkappaB translocation. However, NFkappaB regulatory proteins were not affected by hypothermia. The inflammatory response following GCI and hypothermia's anti-inflammatory mechanism is different from that observed in FCI.

Cerebrospinal fluid cleaved-tau protein and 9-hydroxyoctadecadienoic acid concentrations in pediatric patients with hydrocephalus

OBJECTIVE

To ascertain if cerebrospinal fluid cleaved-tau protein and 9-hydroxyoctadecadienoic acid, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in hydrocephalus patients compared with controls, and if cleaved-tau and 9-hydroxyoctadecadienoic acid levels correlate with each other.

DESIGN

Prospective clinical observational study.

SETTING

Tertiary-care children's hospital.

PATIENTS

Children younger than or equal to 18 yrs who underwent ventriculoperitoneal shunt placement or revision surgery for intrinsic hydrocephalus.

MEASUREMENTS AND MAIN RESULTS

During the study period 12 patients with intrinsic hydrocephalus required ventriculoperitoneal shunt placement or revision. Cerebrospinal fluid cleaved-tau levels were significantly elevated in patients with hydrocephalus (44.7 +/- 9.6 ng/mL, n = 11) compared with control patients (0.0 +/- 0.0 ng/mL, n = 9; p < 0.0001). Cleaved-tau levels correlated with patient age (r = .609, p = 0.047) and duration of symptoms (r = .755, p = 0.007). No significant difference in cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels between patients with hydrocephalus (24.6 +/- 5.7, n = 8) and control patients (24.9 +/- 9.3 ng/mL, n = 7) was detected (p = 0.25). There was also no statistically significant correlation between 9-hydroxyoctadecadienoic acid levels and duration of symptoms (r = .668, p = 0.07), nor was there a significant correlation between 9-hydroxyoctadecadienoic acid levels and patient age (r = -.011, p > 0.10). There was no significant relationship between 9-hydroxyoctadecadienoic acid levels and signs of elevated intracranial pressure, nor was there a correlation between 9-hydroxyoctadecadienoic acid levels and cleaved-tau levels.

CONCLUSION

Children with hydrocephalus who have clinical signs of increased intracranial pressure and require ventriculoperitoneal shunt placement or revision exhibit markedly elevated cerebrospinal fluid cleaved-tau levels, suggesting evidence of axonal damage. However, this axonal injury does not seem to be associated with significant lipid peroxidation, at least as assessed by quantifying cerebrospinal fluid 9-hydroxyoctadecadienoic acid at a single, concurrent time point. The significant relationship between age and cerebrospinal fluid cleaved-tau levels suggest that brain injury associated with hydrocephalus may be more pronounced in older children.

Caspases inhibition decreases neurological sequelae in meningitis

OBJECTIVE

To evaluate the effects of sustained caspase inhibition during the acute phase of meningitis-induced brain injury. Changes in neurobehavioral performance were the primary outcome variables.

DESIGN

Randomized prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Animals underwent a basilar cistern inoculation of group B Streptococci to induce meningitis. Sixteen hours later animals were randomized to receive Bocaspartyl (OMe)-fluoromethyketone (BAF) for 4 days or placebo in addition to antibiotic therapy. The assessment of neurobehavioral performance was started 7 days after initiation of treatment and continued for the following 3 wks. A subgroup underwent early kill, at 5 days, to evaluate caspase 3 activity in brain tissue. There was a group of Sham instrumented animals.

MEASUREMENTS AND MAIN RESULTS

BAF decreased caspase 3 activation in meningitic animals. There were no significant motor deficit differences between the infected groups. Cognitive performance was significantly improved in the BAF group.

CONCLUSION

These findings demonstrate that sustained systemic administration of BAF inhibits caspase 3 activation and decreases neurologic sequelae in a rat model of bacterial meningitis.

Antioxidant treatment prevented late memory impairment in an animal model of sepsis

OBJECTIVE

Assess the effect of antioxidant treatment on late memory impairment and early hippocampus oxidative stress after cecal ligation and perforation.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Rats underwent sham operation or cecal ligation and perforation. Animals that underwent cecal ligation and perforation were divided into groups: 1) treated with basic support (50 mL/kg saline, 30 mg/kg ceftriaxone, and 25 mg/kg clindamycin every 6 hrs), 2) treated with basic support plus N-acetylcysteine (20 mg/kg N-acetylcysteine at 3, 6, 12, 18, and 24 hrs after cecal ligation and perforation), 3) treated with basic support plus deferoxamine (20 mg/kg deferoxamine at 3 and 24 hrs after cecal ligation and perforation), 4) treated with basic support plus N-acetylcysteine and deferoxamine, or 5) treated with N-acetylcysteine plus deferoxamine.

MEASUREMENTS AND MAIN RESULTS

On days 10 and 30 after surgery, the animals underwent behavioral tasks: inhibitory avoidance task, habituation to an open field, and continuous multiple-trials step-down inhibitory avoidance task. The sepsis group showed significantly decreased performance in latency retention compared with the sham group in the inhibitory avoidance task. In the open-field task, the sepsis group presented memory impairment after sepsis. In the continuous multiple-trials step-down inhibitory avoidance task, the sepsis group showed a significant increase in the number of training trials required to reach the acquisition criterion. All these memory impairments were prevented by N-acetylcysteine plus deferoxamine treatment, but not its isolate use. In addition, the combined use of antioxidants attenuated oxidative damage in hippocampus 6 hrs after sepsis induction.

CONCLUSIONS

Antioxidant treatment prevented the development of late cognitive deficits in an animal model of sepsis.

Effects of mild induced hypothermia during experimental sepsis

OBJECTIVES

The potential advantages of lowering core temperature during sepsis are to lower energy requirement and to activate various cell-protecting pathways. We experimentally investigated whether postconditioning temperature modifications influence survival duration during experimental sepsis.

DESIGN

A prospective, randomized, experimental animal study.

SETTING

University laboratory.

SUBJECTS

Eighteen male Sprague-Dawley rats (median 326 g, range 310-347 g).

INTERVENTIONS

After anesthesia, experimental sepsis was induced by cecal ligation and perforation. The animals were subsequently assigned a core temperature range: normothermia (37 degrees C), hyperthermia (42 degrees C), and mild hypothermia (32 degrees C). Anesthesia and analgesia were continuously maintained until death.

MEASUREMENTS AND MAIN RESULTS

Plasma lactate and pyruvate concentrations were measured at sepsis induction (H0), 4 hrs later (H4), and/or at the time of death. A significant increase in lactate concentration was observed at the time of death in the 42 degrees C group (p = .04). Lactate-to-pyruvate ratio increased in the 32 degrees C (at H4) and 42 degrees C (at the time of death) groups (p = .04). A linear correlation between a longer survival duration and a lower assigned core temperature was observed (from 61 +/- 10 mins at 42 degrees C to 289 +/- 17 mins at 37 degrees C and to 533 +/- 69 mins at 32 degrees C; R = .959, p < .0001).

CONCLUSIONS

The current results demonstrate that postconditioning hypothermia was associated with increased survival duration during experimental sepsis. Whether the observed benefits on survival duration are due to potential impacts on energy metabolism or to an anti-inflammatory effect of hypothermia requires further investigation.

Could NF-κB and caspase-3 be markers for estimation of post-interval of human traumatic brain injury?

BACKGROUND

Previous studies in a rat model showed expressions of caspase-3 (p20) and NF-kappaB (p65) in different time after TBI. We test the activation changes of caspase-3 and NF-kappaB of human specimen after traumatic brain injury (TBI) in this study to see whether they could be markers to estimate post-intervals of TBI for forensic practice.

MATERIAL AND METHODS

Caspase-3 (p20) and NF-kappaB (p65) immunohistochemical staining were performed on 39 TBI specimens (dead from TBI) and eight controls (dead from none TBI reasons) grouped 0, 12, 24, 48, 72, 168, 264 and 480 h. Positive cells were counted and image analysis techniques were used to determine the morphological changes in each group.

RESULTS

Immunohistochemical analysis showed a marked induction of caspase-3 (p20) in every injured group compared with normal controls; each positive group has it's morphological character with variant positive cell count. NF-kappaB (p65) did not showed markedly change compared with normal controls until 168 h after TBI and almost all nerve cells were stained by NF-kappaB (p65) in 264 and 480 h groups.

CONCLUSION

NF-kappaB (p65) could contribute to estimate delayed death cases after TBI for forensic applications. Caspase-3 (p20) estimating post-TBI intervals are dubious but could suggest TBI exists.

Dexamethasone decreases neurological sequelae and caspase activity

OBJECTIVE

To evaluate the use of dexamethasone in a model of meningitis-induced brain injury. Changes in neurobehavioral performance were the primary outcome variables. Changes in caspase activation and markers of neuronal injury were the secondary outcome variables.

DESIGN

Randomized, prospective animal study.

SETTING

University research laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Animals underwent a basilar cistern injection of either placebo or a suspension of Group B Streptococcus. Sixteen hours after inoculation, animals were randomized and received either dexamethasone or placebo in addition to antibiotics. Neurobehavioral performance and biological markers of brain injury were assessed at 3 days and 9 days after randomization. In a second experiment, caspase 1 and 3 were evaluated at 6 h, 24 h, and 72 h after dexamethasone administration.

MEASUREMENTS AND MAIN RESULTS

Neurobehavioral performance at 3 days and 9 days was significantly improved in the dexamethasone group. Serum C-tau and cerebral edema were decreased after 3 days of dexamethasone treatment. Dexamethasone decreased Caspase 3 activation in meningitic animals.

CONCLUSION

These findings demonstrate that dexamethasone decreases acute brain injury in a rat model of bacterial meningitis as measured by preservation of neurobehavioral performance.

Hypothermia prolongs activation of NF-kappaB and augments generation of inflammatory cytokines

While moderate hypothermia is protective against ischemic cardiac and brain injury, it is associated with much higher mortality in patients with sepsis. We previously showed that in vitro exposure to moderate hypothermia (32 degrees C) delays the induction and prolongs the duration of TNF-alpha and IL-1beta secretion by lipopolysaccharide (LPS)-stimulated human mononuclear phagocytes. In the present study, we extended these observations by showing that moderate hypothermia exerts effects on TNF-alpha and IL-1beta generation in the human THP-1 monocyte cell line that are similar to those that we previously found in primary cultured monocytes; that hypothermia causes comparable changes in cytokine generation stimulated by zymosan, toxic shock syndrome toxin-1, and LPS; and that hypothermia causes similar changes in TNF-alpha and IL-1beta mRNA accumulation. TNF-alpha mRNA half-life, determined after transcriptional arrest with actinomycin D, was not significantly prolonged by lowering incubation temperature from 37 to 32 degrees C, suggesting that hypothermia modifies TNF-alpha gene transcription. This finding was further supported by reporter gene studies showing a threefold increase in activity of the human TNF-alpha promoter at 32 vs. 37 degrees C. Electrophoretic mobility shift assay revealed that hypothermia prolonged NF-kappaBeta activation, identifying a potential role for this transcription factor in mediating the effects of hypothermia on TNF-alpha and IL-1beta production. Delayed reexpression of the inhibitor IkappaBalpha, shown by Northern blotting and immunoblotting, may account in part for the prolonged NF-kappaBeta activation at 32 degrees C. Augmentation of NF-kappaBeta-dependent gene expression during prolonged exposure to hypothermia may be a common mechanism leading to increased lethality in sepsis, late-onset systemic inflammatory response syndrome after accidental hypothermia, and neuroprotection after ischemia.

Induced hypothermia in critical care medicine: a review

BACKGROUND

Clinical trials of induced hypothermia have suggested that this treatment may be beneficial in selected patients with neurologic injury.

OBJECTIVES

To review the topic of induced hypothermia as a treatment of patients with neurologic and other disorders.

DESIGN

Review article.

INTERVENTIONS

None.

MAIN RESULTS

Improved outcome was demonstrated in two prospective, randomized, controlled trials in which induced hypothermia (33 degrees C for 12-24 hrs) was used in patients with anoxic brain injury following resuscitation from prehospital cardiac arrest. In addition, prospective, randomized, controlled trials have been conducted in patients with severe head injury, with variable results. There also have been preliminary clinical studies of induced hypothermia in patients with severe stroke, newborn hypoxic-ischemic encephalopathy, neurologic infection, and hepatic encephalopathy, with promising results. Finally, animal models have suggested that hypothermia that is induced rapidly following traumatic cardiac arrest provides significant neurologic protection and improved survival.

CONCLUSIONS

Induced hypothermia has a role in selected patients in the intensive care unit. Critical care physicians should be familiar with the physiologic effects, current indications, techniques, and complications of induced hyperthermia.

Impaired cortical energy metabolism but not major antioxidant defenses in experimental bacterial meningitis

The loss of soluble brain antioxidants and protective effects of radical scavengers implicate reactive oxygen species in cortical neuronal injury caused by bacterial meningitis. However, the lack of significant oxidative damage in cortex [J. Neuropathol. Exp. Neurol. 61 (2002) 605-613] suggests that cortical neuronal injury may not be due to excessive parenchymal oxidant production. To see whether this tissue region exhibits a prooxidant state in bacterial meningitis, we examined the state of the major cortical antioxidant defenses in infant rats infected with Streptococcus pneumoniae. Adenine nucleotides were co-determined to assess possible changes in energy metabolism. Arguing against heightened parenchymal oxidant production, the high NADPH/NADP(+) ratio ( approximately 3:1) and activities of the major antioxidant defense and pentose phosphate pathway enzymes remained unchanged at the time of fulminant meningitis. In contrast, cortical ATP, ADP and total adenine nucleotides were on average decreased by approximately 25%. However, energy depletion did not lead to a significant decrease in adenylate energy charge (AEC). ATP depletion was likely a consequence of metabolic degradation, since it correlated with both the loss of total adenine nucleotides and accumulation of purine degradation products. Furthermore, the loss of ATP and decrease in AEC correlated significantly with the extent of neuronal injury. These results strongly suggest that energy depletion rather than parenchymal oxidative damage is involved in the observed cortical neuronal injury.