Complications of head injury

Development of a System for Predicting Hospitalization Time for Patients With Traumatic Brain Injury Based on Machine Learning Algorithms: User-Centered Design Case Study

Background

Currently, the treatment and care of patients with traumatic brain injury (TBI) are intractable health problems worldwide and greatly increase the medical burden in society. However, machine learning-based algorithms and the use of a large amount of data accumulated in the clinic in the past can predict the hospitalization time of patients with brain injury in advance, so as to design a reasonable arrangement of resources and effectively reduce the medical burden of society. Especially in China, where medical resources are so tight, this method has important application value.

Objective

We aimed to develop a system based on a machine learning model for predicting the length of hospitalization of patients with TBI, which is available to patients, nurses, and physicians.

Methods

We collected information on 1128 patients who received treatment at the Neurosurgery Center of the Second Affiliated Hospital of Anhui Medical University from May 2017 to May 2022, and we trained and tested the machine learning model using 5 cross-validations to avoid overfitting; 28 types of independent variables were used as input variables in the machine learning model, and the length of hospitalization was used as the output variables. Once the models were trained, we obtained the error and goodness of fit (R2) of each machine learning model from the 5 rounds of cross-validation and compared them to select the best predictive model to be encapsulated in the developed system. In addition, we externally tested the models using clinical data related to patients treated at the First Affiliated Hospital of Anhui Medical University from June 2021 to February 2022.

Results

Six machine learning models were built, including support vector regression machine, convolutional neural network, back propagation neural network, random forest, logistic regression, and multilayer perceptron. Among them, the support vector regression has the smallest error of 10.22% on the test set, the highest goodness of fit of 90.4%, and all performances are the best among the 6 models. In addition, we used external datasets to verify the experimental results of these 6 models in order to avoid experimental chance, and the support vector regression machine eventually performed the best in the external datasets. Therefore, we chose to encapsulate the support vector regression machine into our system for predicting the length of stay of patients with traumatic brain trauma. Finally, we made the developed system available to patients, nurses, and physicians, and the satisfaction questionnaire showed that patients, nurses, and physicians agreed that the system was effective in providing clinical decisions to help patients, nurses, and physicians.

Conclusions

This study shows that the support vector regression machine model developed using machine learning methods can accurately predict the length of hospitalization of patients with TBI, and the developed prediction system has strong clinical use.

Binary classification model of machine learning detected altered gut integrity in controlled-cortical impact model of traumatic brain injury

Aim of the study: To examine the effect of controlled-cortical impact (CCI), a preclinical model of traumatic brain injury (TBI), on intestinal integrity using a binary classification model of machine learning (ML).Materials and methods: Adult, male C57BL/6 mice were subjected to CCI surgery using a stereotaxic impactor (Impact One™). The rotarod and hot-plate tests were performed to assess the neurological deficits.Results: Mice underwent CCI displayed a remarkable neurological deficit as noticed by decreased latency to fall and lesser paw withdrawal latency in rotarod and hot plate test, respectively. Animals were sacrificed 3 days post-injury (dpi). The colon sections were stained with hematoxylin and eosin (H&E) to integrate with machinery tool-based algorithms. Several stained colon images were captured to build a dataset for ML model to predict the impact of CCI vs sham procedure. The best results were obtained with VGG16 features with SVM RBF kernel and VGG16 features with stacked fully connected layers on top. We achieved a test accuracy of 84% and predicted the disrupted gut permeability and epithelium wall of colon in CCI group as compared to sham-operated mice.Conclusion: We suggest that ML may become an important tool in the development of preclinical TBI model and discovery of newer therapeutics.

Brain-derived extracellular vesicles mediate traumatic brain injury associated multi-organ damage

Traumatic brain injury (TBI) can negatively impact systemic organs, which can lead to more death and disability. However, the mechanism underlying the effect of TBI on systemic organs remains unclear. In previous work, we found that brain-derived extracellular vesicles (BDEVs) released from the injured brain can induce systemic coagulation with a widespread fibrin deposition in the microvasculature of the lungs, kidney, and heart in a mouse model of TBI. In this study, we investigated whether BDEVs can induce heart, lung, liver, and kidney injury in TBI mice. The results of pathological staining and related biomarkers indicated that BDEVs can induce histological damage and systematic dysfunction. In vivo imaging system demonstrated that BDEVs can gather in systemic organs. We also found that BDEVs could induce cell apoptosis in the lung, liver, heart, and kidney. Furthermore, we discovered that BDEVs could cause multi-organ endothelial cell damage. Finally, this secondary multi-organ damage could be relieved by removing circulating BDEVs. Our research provides a novel perspective and potential mechanism of TBI-associated multi-organ damage.

An update on pathophysiology and treatment of sports-mediated brain injury

Traumatic brain injury (TBI) is a neurological disorder which represents a major health issue worldwide. It causes mortality and disability among all group ages, caused by external force, sports-related events or violence and road traffic accidents. In the USA, approximately one-third people die annually due to injury and 1.7 million people suffer from traumatic brain injury. Every year in India around 1.6 million individuals suffer from sustain brain injury with 200,000 deaths and approximately one million person needed recovery treatment at any stage of time. Sports-related head impact and trauma has become an extremely controversial public health and medico-legal problem that accounts for 20% of all brain injury (including concussion). It is difficult to reverse the primary injury but the secondary injury can be minimized by using proper pharmacological intervention during the initial hours of injury. This article highlights the pathophysiology and types of TBI along with treatment therapies. Till date, there is no single medication that can decrease the progression of the disease so that symptomatic treatment is given to the patient by determining proper pathology. Recently various herbal medicine therapies and traditional supplements have been developed for TBI. Nutritional supplementation and nutraceuticals have exposed potential in the treatment of TBI when used before and after TBI. The compiled data will enable the readers to know the pathophysiology as well as the allopathic and natural remedies to treat the TBI.

Altered physiology of gastrointestinal vagal afferents following neurotrauma

The adaptability of the central nervous system has been revealed in several model systems. Of particular interest to central nervous system-injured individuals is the ability for neural components to be modified for regain of function. In both types of neurotrauma, traumatic brain injury and spinal cord injury, the primary parasympathetic control to the gastrointestinal tract, the vagus nerve, remains anatomically intact. However, individuals with traumatic brain injury or spinal cord injury are highly susceptible to gastrointestinal dysfunctions. Such gastrointestinal dysfunctions attribute to higher morbidity and mortality following traumatic brain injury and spinal cord injury. While the vagal efferent output remains capable of eliciting motor responses following injury, evidence suggests impairment of the vagal afferents. Since sensory input drives motor output, this review will discuss the normal and altered anatomy and physiology of the gastrointestinal vagal afferents to better understand the contributions of vagal afferent plasticity following neurotrauma.

Craniocerebral nail gun injuries: a definitive review of the literature

AIM

Nail guns are important time saving devices but are associated with morbidity and mortality. Specifically, craniocerebral injuries have been reported in the literature since 1963 and have increased in frequency as the use of these tools has become commonplace. There remains a paucity of literature comprehensively assessing nail gun injuries, as compared with other penetrating craniocerebral injuries like those from firearms.

METHOD

A literature review of PubMed, Medline (Ovid), Cochrane library, and Google Scholar for articles published between 1960 and 2018 reporting craniocerebral nail gun injuries.

RESULTS

In total, 96 individual cases were identified, with 80 meeting inclusion criteria. These were categorized as accidental and intentional injuries. The demographic was overwhelmingly young males (97.5%), and intentional self-inflicted injuries (54%) was the most frequent mechanism of injury. Overall mortality was 10%. Mortality was more common in patients with intentional injuries, but morbidity rates were similar between the accidental and intentional injury cohorts. Post-operative complications rate was 23.8%.

CONCLUSION

Craniocerebral nail gun injuries are associated with lower rates of both mortality and residual neurological deficits than craniocerebral firearms injuries. There is limited data to inform clinical prognostication about long-term neurological impairments and the time to recovery which should be addressed in future studies.

The microbiota-microglia axis in central nervous system disorders

The innate immune system in the central nervous system (CNS) is mainly represented by specialized tissue-resident macrophages, called microglia. In the past years, various species-, host- and tissue-specific as well as environmental factors were recognized that essentially affect microglial properties and functions in the healthy and diseased brain. Host microbiota are mostly residing in the gut and contribute to microglial activation states, for example, via short-chain fatty acids (SCFAs) or aryl hydrocarbon receptor (AhR) ligands. Thereby, the gut microorganisms are deemed to influence numerous CNS diseases mediated by microglia. In this review, we summarize recent findings of the interaction between the host microbiota and the CNS in health and disease, where we specifically highlight the resident gut microbiota as a crucial environmental factor for microglial function as what we coin "the microbiota-microglia axis."

A Study to Ascertain the Expression of Aquaporin 4 and Neuropeptide Y in the Jejunal Mucosa Secondary to Traumatic Brain Injury in Humans

Introduction Gastrointestinal (GI) dysfunction is a common complication in patients with traumatic brain injury (TBI). Studies in rats have shown alterations in intestinal mucosa to correlate with severity and duration of TBI. There is lack of such evidence in humans. So we intended to find correlation between histopathological changes and expression of aquaporin 4 (AQ4) and neuropeptide Y (NPY) in jejunal mucosa in post TBI patients.

Materials and Methods Autopsy specimens of jejunum were obtained from patients who had died due to TBI (n = 20), patients dying due to traumatic injury other than TBI, and patients who were brought dead (diseased controls n = 20). Abdominal trauma was the exclusion criterion for both. Jejunal specimens were grossly examined and then analyzed histopathologically and graded immunohistochemically for AQ4 and NPY. Unpaired t-test was used to compare results.

Results After exclusion, 19 cases and 17 controls were studied. No significant difference was observed in the microscopic findings between cases and controls (p-value = 0.70). The expression of AQ4 was more in cases (p-value = 0.04). NPY expression was not significantly different (p-value = 0.93).

Conclusion AQ4 can hence be used as a marker of GI injury post TBI. Histopathological examination cannot distinguish between these changes.

Traumatic brain injury causing intestinal dysfunction: A review

Traumatic brain injuries (TBI) and its sequelae are becoming one of the most pressing public health concerns worldwide. It is one of the leading causes of increased morbidity and mortality. The primary insult to the brain can cause ischemic brain injury, paralysis, concussions, death, and other serious complications. Brain injury also involves other systems through a secondary pathway resulting in multiple complications during and after hospitalization. The focus of our article is to assess the literature available on traumatic brain injury and intestinal dysfunctional to highlight the aspects of epidemiology, pathophysiology, and different diagnostic approaches for early diagnosis of gut dysfunction. We review studies done in both humans and animals, to better understand this underrated topic, as it costs billions of dollars to the healthcare industry because of delayed diagnosis.

The Construction of a Radiation-Induced Brain Injury Model and Preliminary Study on the Effect of Human Recombinant Endostatin in Treating Radiation-Induced Brain Injury

Background

The aim of this study was to construct a radiation-induced brain injury (RBI) model and assess the effects of human recombinant endostatin in the treatment of RBI.

Material/Methods

In this study, the RBI model was used. Real-time quantitative polymerase chain reaction, immunohistochemistry, hematoxylin and eosin staining were conducted to detect the mRNA and protein expression of vascular endothelial growth factor (VEGF) and assess the effects of human recombinant endostatin in the treatment of RBI.

Results

In this study, we successfully constructed a RBI model. VEGF mRNA expression was decreased after human recombinant endostatin treatment; however, VEGF protein secretion was increased in brain endothelial cells, and the secretion of VEGF protein was decreased in glial cells and nerve cells. Body weight changes indicated that human recombinant endostatin can increase the risk of weight loss. Brain water content results showed that human recombinant endostatin might aggravate cerebral edema in the acute stage of RBI, but it can reduce the progression of cerebral edema in the early delayed stage. Survival analysis showed that human recombinant endostatin improved the survival rate only in the early stage of RBI.

Conclusions

Radiation can induce vasogenic edema and is associated with the RBI occurrence and development. VEGF protein is highly relevant to the induction of edema and thrombosis in the acute phase of RBI and in the early delayed phase of RBI, including vascular repair and regeneration, thrombus ablation and other events. Human recombinant endostatin can reduce the progression of cerebral edema during the early onset of RBI.

Advanced age promotes colonic dysfunction and gut-derived lung infection after stroke

Bacterial infection a leading cause of death among patients with stroke, with elderly patients often presenting with more debilitating outcomes. The findings from our retrospective study, supported by previous clinical reports, showed that increasing age is an early predictor for developing fatal infectious complications after stroke. However, exactly how and why older individuals are more susceptible to infection after stroke remains unclear. Using a mouse model of transient ischaemic stroke, we demonstrate that older mice (>12 months) present with greater spontaneous bacterial lung infections compared to their younger counterparts (7–10 weeks) after stroke. Importantly, we provide evidence that older poststroke mice exhibited elevated intestinal inflammation and disruption in gut barriers critical in maintaining colonic integrity following stroke, including reduced expression of mucin and tight junction proteins. In addition, our data support the notion that the localized pro‐inflammatory microenvironment driven by increased tumour necrosis factor‐α production in the colon of older mice facilitates the translocation and dissemination of orally inoculated bacteria to the lung following stroke onset. Therefore, findings of this study demonstrate that exacerbated dysfunction of the intestinal barrier in advanced age promotes translocation of gut‐derived bacteria and contributes to the increased risk to poststroke bacterial infection.

Complex interplay of multiple biological systems that contribute to post-stroke infections

Stroke is a leading contributor of death and disability around the world. Despite its recognised debilitating neurological deficits, a devastating clinical complication of surviving stroke patients that needs more attention is infection. Up to half of the patients develop infections after stroke, and a high proportion of them will die as a direct consequence. Major clinical trials that examined preventive antibiotic therapy in stroke patients have demonstrated this method of prevention is not effective as it does not reduce incidence of post-stroke pneumonia or improve patient outcome. Additionally, retrospective studies evaluating the use of β-blockers for the modulation of the sympathetic nervous system to prevent post-stroke infections have given mixed results. Therefore, there is an urgent need for more effective therapeutic options that target the underlying mechanisms of post-stroke infections. The understanding that infections are largely attributable to the "stroke-induced systemic immunosuppression" phenomenon has begun to emerge, and thus, exploring the pathways that trigger post-stroke immunosuppression is expected to reveal potential new therapeutics. As such, we will outline the impacts that stroke has on several biological systems in this review, and discuss how these contribute to host susceptibility to infection after stroke. Furthermore, the emerging role of the gut and its microbiota has recently come to surface and intensifies the complex pathways to post-stroke infection. Finally, we identify potential avenues to combat infection that target the pathways of stroke-induced systemic immunosuppression to ultimately improve stroke patient outcome.

The bidirectional gut-brain-microbiota axis as a potential nexus between traumatic brain injury, inflammation, and disease

As head injuries and their sequelae have become an increasingly salient matter of public health, experts in the field have made great progress elucidating the biological processes occurring within the brain at the moment of injury and throughout the recovery thereafter. Given the extraordinary rate at which our collective knowledge of neurotrauma has grown, new insights may be revealed by examining the existing literature across disciplines with a new perspective. This article will aim to expand the scope of this rapidly evolving field of research beyond the confines of the central nervous system (CNS). Specifically, we will examine the extent to which the bidirectional influence of the gut-brain axis modulates the complex biological processes occurring at the time of traumatic brain injury (TBI) and over the days, months, and years that follow. In addition to local enteric signals originating in the gut, it is well accepted that gastrointestinal (GI) physiology is highly regulated by innervation from the CNS. Conversely, emerging data suggests that the function and health of the CNS is modulated by the interaction between 1) neurotransmitters, immune signaling, hormones, and neuropeptides produced in the gut, 2) the composition of the gut microbiota, and 3) integrity of the intestinal wall serving as a barrier to the external environment. Specific to TBI, existing pre-clinical data indicates that head injuries can cause structural and functional damage to the GI tract, but research directly investigating the neuronal consequences of this intestinal damage is lacking. Despite this void, the proposed mechanisms emanating from a damaged gut are closely implicated in the inflammatory processes known to promote neuropathology in the brain following TBI, which suggests the gut-brain axis may be a therapeutic target to reduce the risk of Chronic Traumatic Encephalopathy and other neurodegenerative diseases following TBI. To better appreciate how various peripheral influences are implicated in the health of the CNS following TBI, this paper will also review the secondary biological injury mechanisms and the dynamic pathophysiological response to neurotrauma. Together, this review article will attempt to connect the dots to reveal novel insights into the bidirectional influence of the gut-brain axis and propose a conceptual model relevant to the recovery from TBI and subsequent risk for future neurological conditions.

The gut reaction to traumatic brain injury

Traumatic brain injury (TBI) is a complex disorder that affects millions of people worldwide. The complexity of TBI partly stems from the fact that injuries to the brain instigate non-neurological injuries to other organs such as the intestine. Additionally, genetic variation is thought to play a large role in determining the nature and severity of non-neurological injuries. We recently reported that TBI in flies, as in humans, increases permeability of the intestinal epithelial barrier resulting in hyperglycemia and a higher risk of death. Furthermore, we demonstrated that genetic variation in flies is also pertinent to the complexity of non-neurological injuries following TBI. The goals of this review are to place our findings in the context of what is known about TBI-induced intestinal permeability from studies of TBI patients and rodent TBI models and to draw attention to how studies of the fly TBI model can provide unique insights that may facilitate diagnosis and treatment of TBI.

Hypertonic saline alleviates experimentally induced cerebral oedema through suppression of vascular endothelial growth factor and its receptor VEGFR2 expression in astrocytes

BACKGROUND

Cerebral oedema is closely related to the permeability of blood-brain barrier, vascular endothelial growth factor (VEGF) and its receptor vascular endothelial growth factor receptor 2 (VEGFR2) all of which are important blood-brain barrier (BBB) permeability regulatory factors. Zonula occludens 1 (ZO-1) and claudin-5 are also the key components of BBB. Hypertonic saline is widely used to alleviate cerebral oedema. This study aimed to explore the possible mechanisms underlying hypertonic saline that ameliorates cerebral oedema effectively.

METHODS

Middle cerebral artery occlusion (MCAO) model in Sprague-Dawley (SD) rats and of oxygen-glucose deprivation model in primary astrocytes were used in this study. The brain water content (BWC) was used to assess the effect of 10 % HS on cerebral oedema. The assessment of Evans blue (EB) extravasation was performed to evaluate the protective effect of 10 % HS on blood-brain barrier. The quantification of VEGF, VEGFR2, ZO-1 and claudin-5 was used to illustrate the mechanism of 10 % HS ameliorating cerebral oedema.

RESULTS

BWC was analysed by wet-to-dry ratios in the ischemic hemisphere of SD rats; it was significantly decreased after 10 % HS treatment (P < 0.05). We also investigated the blood-brain barrier protective effect by 10 % HS which reduced EB extravasation effectively in the peri-ischemic brain tissue. In parallel to the above notably at 24 h following MCAO, mRNA and protein expression of VEGF and VEGFR2 in the peri-ischemic brain tissue was down-regulated after 10 % HS treatment (P < 0.05). Along with this, in vitro studies showed increased VEGF and VEGFR2 mRNA and protein expression in primary astrocytes under hypoxic condition (P < 0.05), but it was suppressed after HS treatment (P < 0.05). In addition, HS inhibited the down-regulation of ZO-1, claudin-5 effectively.

CONCLUSIONS

The results suggest that 10 % HS could alleviate cerebral oedema possibly through reducing the ischemia induced BBB permeability as a consequence of inhibiting VEGF-VEGFR2-mediated down-regulation of ZO-1, claudin-5.

Ghrelin Improves Antioxidant Defense in Blood and Brain in Normobaric Hypoxia in Adult Male Rats

PURPOSE

Hypoxia is one of the important factors in formation of reactive oxygen species (ROS). Ghrelin is a peptide hormone that reduces oxidative stress. However, antioxidant effect of ghrelin on blood and brain in normobaric hypoxia condition has not yet been investigated.

METHODS

thirty-two animals were randomly divided into four (n=8) experimental groups: Control (C), ghrelin (Gh), hypoxia (H), hypoxic animals that received ghrelin (H+Gh). Normobaric systemic hypoxia (11% O2) was induced in rats for 48 hours. Effect of ghrelin (80 μg/kg, i.p) on serum TAC and MDA and brain SOD, CAT, GPx and MDA were assessed.

RESULTS

Hypoxia significantly (p<0.001) increased both blood and brain MDA Levels. Ghrelin treatment significantly (p<0.001) decreased blood MDA levels both in control and hypoxia, and brain MDA levels in hypoxia conditions. Brain SOD, CAT and GPx variations were not significant in two days of hypoxia. Ghrelin treatment also could not significantly increase activity of SOD, CAT and GPx in brain. Total antioxidant capacity of serum increased in ghrelin treatment both in control and hypoxic conditions, although it was only significant (p<0.01) in control conditions.

CONCLUSION

Our findings showed that administration of ghrelin may be useful in reducing blood and brain oxidative stress in normobaric hypoxia condition.

The effects of female sexual steroids on gastric function and barrier resistance of gastrointestinal tract following traumatic brain injury

AIM

The aim was to assess the alteration of gastric function and barrier function of gastrointestinal (GI) tract following diffuse brain injury in varying ovarian hormone status.

MATERIALS AND METHODS

Diffuse traumatic brain injury (TBI) was induced by Marmarou method. Rats were randomly assigned into 10 groups: Intact, sham + ovariectomized female (OVX), TBI, TBI + OVX, vehicle, estradiol (E2), progesterone (P), E2 + P, estrogen receptor alpha agonist and estrogen receptor beta agonist (DPN). Endotoxin levels were measured using enzyme-linked immunosorbent assay method. All the parameters were measured 5 days after TBI.

RESULTS

Intragastric pressure was significantly decreased in TBI as compared to the intact group (P < 0.001) and this was lower in TBI group versus TBI + OVX group (P < 0.05). Pretreatment with steroid hormones and their agonists did not have any effect on the gastric pressure compared to TBI + OVX or vehicle groups. Inflammation, congestion, ulcer and erosion were seen in the TBI rats. All treatment groups worsen the tissue condition so that the presence of thrombosis also was seen. The trauma induction did not have any effect on the serum and intestinal endotoxin levels. DPN had caused a significant reduction in serum levels of endotoxin compared with OVX + TBI group (P < 0.05).

CONCLUSION

Pretreatment with sexual steroids is not useful in the treatment of GI dysfunction induced by TBI. The treatment with all sexual female hormones worsens the gastric tissue condition. Furthermore, the applied weight was not enough for releasing of endotoxin. It seems that estrogen reduced the endotoxin levels by estrogen beta receptor.

Alterations in enterocyte mitochondrial respiratory function and enzyme activities in gastrointestinal dysfunction following brain injury

AIM: To determine the alterations in rat enterocyte mitochondrial respiratory function and enzyme activities following traumatic brain injury (TBI).

METHODS: Fifty-six male SD rats were randomly divided into seven groups (8 rats in each group): a control group (rats with sham operation) and traumatic brain injury groups at 6, 12, 24 h, days 2, 3, and 7 after operation. TBI models were induced by Feendy’s free-falling method. Mitochondrial respiratory function (respiratory control ratio and ADP/O ratio) was measured with a Clark oxygen electrode. The activities of respiratory chain complex I-IV and related enzymes were determined by spectrophotometry.

RESULTS: Compared with the control group, the mitochondrial respiratory control ratio (RCR) declined at 6 h and remained at a low level until day 7 after TBI (control, 5.42 ± 0.46; 6 h, 5.20 ± 0.18; 12 h, 4.55 ± 0.35; 24 h, 3.75 ± 0.22; 2 d, 4.12 ± 0.53; 3 d, 3.45 ± 0.41; 7 d, 5.23 ± 0.24, P < 0.01). The value of phosphate-to-oxygen (P/O) significantly decreased at 12, 24 h, day 2 and day 3, respectively (12 h, 3.30 ± 0.10; 24 h, 2.61 ± 0.21; 2 d, 2.95 ± 0.18; 3 d, 2.76 ± 0.09, P < 0.01) compared with the control group (3.46 ± 0.12). Two troughs of mitochondrial respiratory function were seen at 24 h and day 3 after TBI. The activities of mitochondrial complex I (6 h: 110 ± 10, 12 h: 115 ± 12, 24 h: 85 ± 9, day 2: 80 ± 15, day 3: 65 ± 16, P < 0.01) and complex II (6 h: 105 ± 8, 12 h: 110 ± 92, 24 h: 80 ± 10, day 2: 76 ± 8, day 3: 68 ± 12, P < 0.01) were increased at 6 h and 12 h following TBI, and then significantly decreased at 24 h, day 2 and day 3, respectively. However, there were no differences in complex I and II activities between the control and TBI groups. Furthermore, pyruvate dehydrogenase (PDH) activity was significantly decreased at 6 h and continued up to 7 d after TBI compared with the control group (6 h: 90 ± 8, 12 h: 85 ± 10, 24 h: 65 ± 12, day 2: 60 ± 9, day 3: 55 ± 6, day 7: 88 ± 11, P < 0.01). The changes in α-ketoglutaric dehydrogenase (KGDH) activity were similar to PDH, except that the decrease in KGDH activity began at 12 h after TBI (12 h: 90 ± 12, 24 h: 80 ± 9, day 2: 76 ± 15, day 3: 68 ± 7, day 7: 90 ± 13, P < 0.01). No significant change in malate dehydrogenase (MDH) activity was observed.

CONCLUSION: Rat enterocyte mitochondrial respiratory function and enzyme activities are inhibited following TBI. Mitochondrial dysfunction may play an important role in TBI-induced gastrointestinal dysfunction.

Randomized trial of two swallowing assessment approaches in patients with acquired brain injury: Facial-Oral Tract Therapy versus Fibreoptic Endoscopic Evaluation of Swallowing

Objective:

To examine whether patients assessed for initiation of oral intake only by Facial-Oral Tract Therapy had a greater risk of developing aspiration pneumonia during neurorehabilitation than patients assessed by Fibreoptic Endoscopic Evaluation of Swallowing.

Design:

Randomized controlled trial.

Setting:

Specialized, national neurorehabilitation centre.

Subjects:

Adult patients with acquired brain injury. Six hundred and seventy-nine patients were assessed for eligibility and 138 were randomly allocated between June 2009 and April 2011.

Interventions:

Assessment by Facial-Oral Tract Therapy (control group) or Fibreoptic Endoscopic Evaluation of Swallowing (intervention group).

Main measure:

Primary outcome was the number of aspiration pneumonias that developed after initiation of oral intake.

Results:

One hundred and nineteen patients were included in the analysis of the primary outcome (62 controls/57 interventions). Sixteen patients were clinically diagnosed with pneumonia (4 controls/12 interventions). Nine patients had to be excluded: 6 patients got pneumonia before initiating oral intake; 3 patients with the clinical diagnosis of pneumonia did not show radiological signs. Seven patients were left for analysis, 4 of whom developed aspiration pneumonia within 10 days after initiating oral intake (1 control/3 interventions).

Conclusion:

In the presence of a structured clinical assessment with the Facial-Oral Tract Therapy approach, it is unnecessary to undertake an instrumental investigation of swallowing before initiation of oral intake.

Effect of ghrelin on brain edema induced by acute and chronic systemic hypoxia

Hypoxia is an important pathogenic factor for the induction of vascular leakage and brain edema formation. Recent studies suggest a role for TNF-α in the induction of brain edema. Ghrelin attenuates the synthesis of TNF-α following subarachnoid hemorrhage and traumatic brain injury (TBI). Therefore, we examined the effects of ghrelin on the brain edema, serum TNF-α levels and body weight in a systemic hypoxia model. Adult male Wistar rats were divided into acute and chronic controls, acute or chronic hypoxia and ghrelin-treated (80μg/kg/ip/daily) acute or chronic hypoxia groups. Systemic hypoxia was induced in rats by a normobaric hypoxic chamber (O(2) 11%) for two days (acute) or ten days (chronic). Effect of ghrelin on brain edema and serum TNF-α levels was assessed by dry-wet and ELISA method, respectively. The results showed that acute (P<0.001) and chronic (P<0.05) hypoxia caused an increase of brain water content. Administration of ghrelin only in the acute hypoxia group significantly (P<0.001) reduced brain water content. Acute hypoxia caused an increase of serum TNF-α level (P<0.001) and ghrelin significantly (P<0.001) reduced it. TNF-α level in chronic hypoxia did not change significantly. Both acute and chronic hypoxia decreased body weight significantly (P<0.001) and administration of ghrelin only could prevent further weight loss in chronic hypoxia group (P<0.001). Our findings show that administration of ghrelin may be useful in reducing brain edema induced by acute systemic hypoxia and at least part of the anti-edematous effects of ghrelin is due to decrease of serum TNF-α levels.

Over-expression of Slit2 induces vessel formation and changes blood vessel permeability in mouse brain

AIM

To investigate the effect of the axon guidance cue Slit2 on the density of blood vessels and permeability of the blood-brain barrier in mouse brain.

METHODS

hSlit2 transgenic mouse line was constructed, and the phenotypes of the mice were compared with wild-type mice in respect to the lateral ventricle (LV), ventricle pressure, and the choroids plexus. An in vivo Miles permeability assay and an amyloid-β permeability assay were used to assess the permeability of brain blood vessels. Brain vessel casting and intracerebral hemorrhage models were built to investigate vessel density in the transgenic mice. An in vitro permeability assay was used to test whether Slit2 could change the permeability and tight junctions of blood vessel endothelial cells.

RESULTS

Hydrocephalus occurred in some transgenic mice, and a significantly larger lateral ventricle area and significantly higher ventricle pressure were observed in the transgenic mice. The transgenic mice displayed changed construction of the choroids plexus, which had more micro vessels, dilated vessels, gaps between epithelial cells and endothelial cells than wild-type mice. Slit2 significantly increased brain vessel density and the permeability of brain vessels to large molecules. These blood vessels were more sensitive to cues that induce brain hemorrhage. At the cellular level, Slit2 disturbed the integrity of tight junctions in blood vessel endothelial cells and improved the permeability of the endothelial cell layer. Thus, it promoted the entry of amyloid-β peptides from the serum into the central nervous system, where they bound to neurons.

CONCLUSION

Slit2 increases vessel density and permeability in the brains of transgenic mice. Thus, Slit2 induces numerous changes in brain vessels and the barrier system.

Effects of tert-butylhydroquinone on intestinal inflammatory response and apoptosis following traumatic brain injury in mice

Traumatic brain injury (TBI) can induce intestinal inflammatory response and mucosal injury. Antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) has been shown in our previous studies to prevent oxidative stress and inflammatory response in gut after TBI. The objective of this study was to test whether tert-butylhydroquinone (tBHQ), an Nrf2 inducer, can protect against TBI-induced intestinal inflammatory response and mucosal injury in mice. Adult male ICR mice were randomly divided into three groups: (1) sham + vehicle group, (2) TBI + vehicle group, and (3) TBI + tBHQ group (n = 12 per group). Closed head injury was adopted using Hall's weight-dropping method. Intestinal mucosa apoptosis and inflammatory-related factors, such as nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1), were investigated at 24 h after TBI. As a result, we found that oral treatment with 1% tBHQ prior to TBI for one week markedly decreased NF-κB activation, inflammatory cytokines production, and ICAM-1 expression in the gut. Administration of tBHQ also significantly attenuated TBI-induced intestinal mucosal apoptosis. The results of the present study suggest that tBHQ administration could suppress the intestinal inflammation and reduce the mucosal damage following TBI.

Traumatic brain injury and aeromedical evacuation: when is the brain fit to fly?

BACKGROUND

To review the inflammatory sequelae of traumatic brain injury (TBI) and altitude exposure and discuss the potential impact of aeromedical evacuation (AE) on this process.

METHODS

Literature review and expert opinion regarding the inflammatory effects of TBI and AE.

RESULTS

Traumatic brain injury has been called the signature injury of the current military conflict. As a result of the increasing incidence of blast injury, TBI is responsible for significant mortality and enduring morbidity in injured soldiers. Common secondary insults resulting from post-traumatic cerebral inflammation are recognized to adversely impact outcome. AE utilizing Critical Care Air Transport Teams has become a standard of care practice following battlefield injury, to quickly and safely transport critically injured soldiers to more sophisticated echelons of care. Exposure to the hypobaric conditions of the AE process may impose an additional physiologic risk on the TBI patient as well as a "second hit" inflammatory stimulus.

CONCLUSIONS

We review the known inflammatory effects of TBI and altitude exposure and propose that optimizing the post-traumatic inflammatory profile may assist in determining an ideal time to fly for head-injured soldiers.

Even low-grade inflammation impacts on small intestinal function

Independent of the cause and location, inflammation - even when minimal - has clear effects on gastrointestinal morphology and function. These result in altered digestion, absorption and barrier function. There is evidence of reduced villus height and crypt depth, increased permeability, as well as altered sugar and peptide absorption in the small intestine after induction of inflammation in experimental models, which is supported by some clinical data. Identification of inflammatory factors which may promote the process of gastrointestinal dysfunction as well as clinical research to verify experimental observations of inflammatory modulation of gastrointestinal function are required. Moreover, nutritional strategies to support functional restitution are needed.

Detrimental consequences of brain injury on peripheral cells

Acute brain injury and brain death exert detrimental effects on peripheral host cells. Brain-induced impairment of immune function makes patients more vulnerable to infections that are a major cause of morbidity and mortality after stroke, trauma, or subarachnoid hemorrhage (SAH). Systemic inflammation and organ dysfunction are other harmful consequences of CNS injury. Brain death, the most severe consequence of brain injury, causes inflammatory changes in peripheral organs that can contribute to the inferior outcome of organs transplanted from brain-dead donors. Understanding of the mechanisms underlying the detrimental effects of brain injury on peripheral organs remains incomplete. However, it appears that sympathetic nervous system (SNS)-activation contributes to elicit both inflammation and immunodepression. Indeed, norepinephrine (NE)-induced production of chemokines in liver and other organs likely participates in local and systemic inflammatory changes. Conversely, catecholamine-stimulated interleukin-10 (IL-10) production by blood monocytes exerts immunosuppressive effects. Activation of the hypothalamic-pituitary-adrenal axis (HPA) by increased inflammatory cytokines within the brain is a significant component in the CNS-induced immune function inhibition. Non-neurologic consequences of brain injury show impressive similarities regardless of the brain insult and appear to depend on altered neuroimmune circuits. Modulation of these circuits could reduce extra-brain damage and improve patient outcome in both vascular and traumatic brain injury.

Transcription factor Nrf2 plays a pivotal role in protection against traumatic brain injury-induced acute intestinal mucosal injury in mice

BACKGROUND

Traumatic brain injury (TBI) can induce an acute intestinal mucosal injury. Nuclear factor erythroid 2-related factor 2 (Nrf2) has a unique role in many physiological stress processes, but its contribution to intestinal mucosal injury after TBI remains to be determined.

MATERIALS AND METHODS

Wildtype Nrf2 (+/+) and Nrf2 (-/-) deficient mice were subjected to a moderately severe weight-drop impact head injury. Intestinal mucosal morphological changes, plasma endotoxin, intestinal permeability, apoptosis, inflammatory cytokines, and antioxidant/detoxifying enzymes were measured at 24 hours after TBI.

RESULTS

Nrf2 deficient mice were found to be more susceptible to TBI-induced acute intestinal mucosal injury, as characterized by the higher increase in gut structure damage, plasma endotoxin, intestinal permeability, and apoptosis after TBI. This exacerbation of intestinal mucosal injury in Nrf2 deficient mice was associated with increased intestinal mRNA and protein expression of inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1beta and interleukin-6, and with decreased intestinal mRNA expression and activity levels of antioxidant and detoxifying enzymes including NAD(P)H: quinone oxidoreductase 1 (NQO1) and glutathione S-transferase alpha-1 (GST-alpha1), compared with their wildtype Nrf2 (+/+) counterparts after TBI.

CONCLUSIONS

We show for the first time that mice lacking Nrf2 are more susceptible to TBI-induced acute intestinal mucosal injury. Our data suggests that Nrf2 plays an important role in protecting TBI-induced intestinal mucosal injury, possibly by regulating of inflammatory cytokines and inducing of antioxidant and detoxifying enzymes.

Increased intestinal inflammatory response and gut barrier dysfunction in Nrf2-deficient mice after traumatic brain injury

AIM

To explore the role of nuclear factor erythroid 2-related factor 2 (Nrf2) in traumatic brain injury (TBI)-induced intestinal inflammatory response and gut barrier dysfunction in the mice.

METHODS

Wild-type Nrf2 (+/+) and Nrf2 (-/-)-deficient mice were subjected to a moderately severe weight-drop impact-acceleration head injury. We measured nuclear factor kappa B (NF-kappaB) by electrophoretic mobility shift assay (EMSA); tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) by enzyme-linked immunosorbent assay (ELISA); intercellular adhesion molecule-1 (ICAM-1) by immunohistochemistry; intestinal permeability by lactulose/mannitol (L/M) test; plasma endotoxin by chromogenic limulus amebocyte lysate test.

RESULTS

Intestinal levels of NF-kappaB, pro-inflammatory cytokines and ICAM-1 in Nrf2 (-/-)-deficient mice were significantly higher compared with Nrf2 (+/+) mice at 24h after TBI. Furthermore, higher intestinal permeability and plasma level of endotoxin were observed in the Nrf2 (-/-) mice compared with Nrf2 (+/+) mice.

CONCLUSION

Nrf2 plays an important protective role in limiting intestinal inflammatory response and gut barrier dysfunction after TBI.

Increased intestinal permeability in rats subjected to traumatic frontal lobe percussion brain injury

BACKGROUND

Dysfunction of the gastrointestinal tract is a common occurrence after traumatic brain injury (TBI). We hypothesized that increased intestinal permeability may result from a precisely controlled percussion injury to the exposed brains of anesthetized rats and that such an effect could be assessed in vitro using excised intestinal mucosae mounted in Ussing chambers.

METHODS

After craniotomy over the left medial prefrontal cortex on anesthetized rats, neurotrauma was produced using a pneumatically driven impactor on the exposed brain. Control rats were subjected to identical procedures but did not receive an impact. Muscle-stripped rat intestinal ileal and colonic segments were mounted in Ussing chambers within 30 minutes of death. Transepithelial electrical resistance (TEER) and the apparent permeability coefficient (Papp) of [C]-mannitol were recorded from intestinal tissue for 120 minutes. Histopathologic analysis was also performed to determine any gross morphologic changes in the intestine.

RESULTS

Ileal and colonic mucosae showed no differences in TEER in ileum or colon of TBI rats compared with controls. The Papp of mannitol was significantly increased in ilea from rats previously exposed to TBI compared with controls. Histologic analysis showed gross changes to 50% of the ileal but not the colonic sections from TBI rats.

CONCLUSION

TBI results in significantly reduced ileal barrier function, most likely mediated by open tight junctions. For patients with acute head injury, this may have implications for subsequent oral absorption of nutrients. Systemic delivery of luminal endotoxins may contribute to multiple organ failure.

Splanchnic ischemia and gut permeability after acute brain injury secondary to intracranial hemorrhage

INTRODUCTION

Splanchnic ischemia (SI) and increased gut permeability (GP) have been described in acute brain injury (ABI), although their incidence and relation to the type and severity of injury are uncertain. The aim of this study was to evaluate the incidence of both abnormalities in a series of patients with severe ABI secondary to intracranial hemorrhage (ICH) managed with a resuscitation protocol pursuing adequate cerebral and systemic hemodynamics.

METHODS

Eight patients with severe ABI secondary to ICH were admitted to the ICU and were mechanically ventilated and monitored with intracranial pressure measurement, jugular bulb venous oxygen saturation, arterial lactate concentration and gastric tonometry. All patients were managed actively to maintain adequate blood and cerebral perfusion pressures with a protocol based on aggressive fluid resuscitation prior to vasoactive drugs administration. GP was assessed using the lactulose/mannitol test (LMT). Values were recorded during the first 7 days of hospital stay.

RESULTS

Arterial lactate concentration was within the normal range (1.9 +/- 0.5 mmol/l) in all patients. Upon admission, the mean pCO(2) gap was 8.2 +/- 4.3 mmHg (1.09 +/- 0.57 kPa) with an intramucosal pH of 7.4 +/- 0.1. All patients had an abnormal LMT (0.066 +/- 0.055) compared with 19 healthy volunteers (0.025 +/- 0.004) (p < 0.05, Mann Whitney test).

CONCLUSION

Splanchnic ischemia is uncommon among patients with acute brain injury secondary to intracranial hemorrhage, provided they are adequately resuscitated with a protocol based mainly on fluids to achieve an adequate CPP. Gut hyperpermeability is commonly present, despite the absence of splanchnic ischemia.

Current incidence and management of children with traumatic head injuries: the Stockholm experience

PURPOSE

A traumatic head injury is one of the most common causes of morbidity and mortality among children, however few population-based studies in this area have been reported. Therefore, the aim of this study was to evaluate the incidence and management of traumatic head injuries in children at a level-one trauma centre in Stockholm, Sweden.

PARTICIPANTS

All children (n = 3168) who visited the emergency department with a history of head injury during 1 year were included.

METHOD

The required information was collected retrospectively and the children's medical records were reviewed.

RESULTS

The overall incidences of head injury were 865 per 100 000 children with the highest incidence (2379/10(5) children) occurring among children younger than 18 months of age. Twelve per cent (n = 396) were admitted to a hospital ward and CT scans were performed in 13% (n = 412) of all children. During this year, 0.3% required a neurosurgical intervention and only 1% of all children had documentation of a planned follow-up appointment.

CONCLUSION

The findings indicate that clinical documentation as a part of the early management in children with a head injury is inconsistent and suffers from lack of valid criteria. Implementation of clinical guidelines during emergency care would help improve subsequent hospital care, as well as the planning of health care services for these children.

Levels of vasoactive intestinal peptide, cholecystokinin and calcitonin gene-related peptide in plasma and jejunum of rats following traumatic brain injury and underlying significance in gastrointestinal dysfunction

AIM: To study the alterations of brain-gut peptides following traumatic brain injury (TBI) and to explore the underlying significance of these peptides in the complicated gastrointestinal dysfunction.

METHODS: Rat models of focal traumatic brain injury were established by impact insult method, and divided into 6 groups (6 rats each group) including control group with sham operation and TBI groups at postinjury 3, 12, 24, 72 h, and d 7. Blood and proximal jejunum samples were taken at time point of each group and gross observations of gastrointestinal pathology were recorded simultaneously. The levels of vasoactive intestinal peptide (VIP) in plasma, calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in both plasma and jejunum were measured by enzyme immunoassay (EIA). Radioimmunoassay (RIA) was used to determine the levels of VIP in jejunum.

RESULTS: Gastric distension, delayed gastric emptying and intestinal dilatation with a large amount of yellowish effusion and thin edematous wall were found in TBI rats through 12 h and 72 h, which peaked at postinjury 72 h. As compared with that of control group (247.8 ± 29.5 ng/L), plasma VIP levels were significantly decreased at postinjury 3, 12 and 24 h (106.7 ± 34.1 ng/L, 148.7 ± 22.8 ng/L, 132.8 ± 21.6 ng/L, respectively), but significantly increased at 72 h (405.0 ± 29.8 ng/L) and markedly declined on d 7 (130.7 ± 19.3 ng/L). However, Plasma levels CCK and CGRP were significantly increased through 3 h and 7 d following TBI (126-691% increases), with the peak at 72 h. Compared with control (VIP, 13.6 ± 1.4 ng /g; CGRP, 70.6 ± 17.7 ng/g); VIP and CGRP levels in jejunum were significantly increased at 3 h after TBI (VIP, 35.4 ± 5.0 ng/g; CGRP, 103.8 ± 22.1 ng/g), and declined gradually at 12 h and 24 h (VIP, 16.5 ± 1.8 ng/g, 5.5 ± 1.4 ng/g; CGRP, 34.9 ± 9.7 ng/g, 18.5 ± 7.7 ng/g), but were significantly increased again at 72 h (VIP, 48.7 ± 9.5 ng/g; CGRP, 142.1 ± 24.3 ng/g), then declined in various degrees on d 7 (VIP, 3.8 ± 1.1 ng/g; CGRP, 102.5 ± 18.1 ng/g). The CCK levels in jejunum were found to change in a similar trend as that in plasma with the concentrations of CCK significantly increased following TBI (99-517% increases) and peaked at 72 h.

CONCLUSION: Traumatic brain injury can lead to significant changes of brain-gut peptides in both plasma and small intestine, which may be involved in the pathogenesis of complicated gastrointestinal dysfunction.

Alterations of intestinal mucosa structure and barrier function following traumatic brain injury in rats

AIM: Gastrointestinal dysfunction is a common complication in patients with traumatic brain injury (TBI). However, the effect of traumatic brain injury on intestinal mucosa has not been studied previously. The aim of the current study was to explore the alterations of intestinal mucosa morphology and barrier function, and to determine how rapidly the impairment of gut barrier function occurs and how long it persists following traumatic brain injury.

METHODS: Male Wistar rats were randomly divided into six groups (6 rats each group) including controls without brain injury and traumatic brain injury groups at hours 3, 12, 24, and 72, and on day 7. The intestinal mucosa structure was detected by histopathological examination and electron microscopy. Gut barrier dysfunction was evaluated by detecting serum endotoxin and intestinal permeability. The level of serum endotoxin and intestinal permeability was measured by using chromogenic limulus amebocyte lysate and lactulose/mannitol (L/M) ratio, respectively.

RESULTS: After traumatic brain injury, the histopathological alterations of gut mucosa occurred rapidly as early as 3 hours and progressed to a serious state, including shedding of epithelial cells, fracture of villi, focal ulcer, fusion of adjacent villi, dilation of central chyle duct, mucosal atrophy, and vascular dilation, congestion and edema in the villous interstitium and lamina propria. Apoptosis of epithelial cells, fracture and sparseness of microvilli, loss of tight junction between enterocytes, damage of mitochondria and endoplasm, were found by electron microscopy. The villous height, crypt depth and surface area in jejunum decreased progressively with the time of brain injury. As compared with that of control group (183.7 ± 41.8 EU/L), serum endotoxin level was significantly increased at 3, 12, and 24 hours following TBI (434.8 ± 54.9 EU/L, 324.2 ± 61.7 EU/L and 303.3 ± 60.2 EU/L, respectively), and peaked at 72 hours (560.5 ± 76.2 EU/L), then declined on day 7 (306.7 ± 62.4 EU/L, P < 0.01). Two peaks of serum endotoxin level were found at hours 3 and 72 following TBI. L/M ratio was also significantly higher in TBI groups than that in control group (control, 0.0172 ± 0.0009; 12 h, 0.0303 ± 0.0013; 24 h, 0.0354 ± 0.0025; 72 h, 0.0736 ± 0.0105; 7 d, 0.0588 ± 0.0083; P < 0.01).

CONCLUSION: Traumatic brain injury can induce significant damages of gut structure and impairment of barrier function which occur rapidly as early as 3 hours following brain injury and lasts for more than 7 days with marked mucosal atrophy.

Assessment of prognostic factors in severe traumatic brain injury patients treated by mild therapeutic cerebral hypothermia therapy

This study analyzed the predictable factors of outcome such as neuro-parameters and systemic complications to elucidate the indications for therapeutic hypothermia. In our institute, 35 patients with severe head injury (Glasgow Coma Scale 3-7) were treated with mild hypothermia therapy (33 degrees-35 degrees C). Twenty-two of these 35 patients underwent complete neuromonitoring and outcome assessments by Glasgow Outcome Scale (GOS) at three months after injury. GOS of hypothermia group was significantly better than another patient group which was treated without mild hypothermia therapy. The hypothermia group was divided into two groups: good outcome (GOOD) (good recovery or moderate disability; n = 9, 40.9%) and poor outcome (POOR) (severe disability, vegetative state, or death; n = 13, 59.1%). The mean age (mean 30.2 years, range 9-46) was significantly lower in GOOD than in POOR (mean 45.2 years, range 17-62). Patients aged over 50 years had poor outcome. CPP was significantly higher in GOOD during hypothermia. All patients with thrombocytopenia had poor outcome. Hypothermia therapy can improve outcome in patients with traumatic brain injury who are younger than 50 years old, without severe brain damage, and if improvement of cerebral perfusion is expected. Systemic complications must be prevented as far as possible by combination with other therapies.