Cytokines and metabolic dysfunction after severe head injury

Transforming growth factor-β1 protects mechanically injured cortical murine neurons by reducing trauma-induced autophagy and apoptosis

Transforming growth factor β1 (TGF-β1) has a neuroprotective function in traumatic brain injury (TBI) through its anti-inflammatory and immunomodulatory properties. However, the precise mechanisms underlying the neuroprotective actions of TGF-β1 on the cortex require further investigation. In this study, we were aimed to investigate the regulatory function of TGF-β1 on neuronal autophagy and apoptosis using an in vitro primary cortical neuron trauma-injury model. LDH activity was assayed to measure cell viability, and intracellular [Ca2+] was measured using Fluo-4-AM in an in vitro primary cortical neuron trauma-injury model. RNA-sequencing (RNAseq), immunofluorescent staining, transmission electron microscopy (TEM), western blot and CTSD activity detection were employed. We observed significant enrichment of DEGs related to autophagy, apoptosis, and the lysosome pathway in trauma-injured cortical neurons. TEM confirmed the presence of autophagosomes as well as autophagolysosomes. Western blot revealed upregulation of autophagy-related protein light chain 3 (LC3-II/LC3-I), sequestosome 1 (SQSTM1/p62), along with apoptosis-related protein cleaved-caspase 3 in trauma-injured primary cortical neurons. Furthermore, trauma-injured cortical neurons showed an upregulation of lysosomal marker protein (LAMP1) and lysosomal enzyme mature cathepsin D (mCTSD), but a decrease in the activity of CTSD enzyme. These results indicated that apoptosis was up-regulated in trauma- injured cortical neurons at 24 h, accompanied by lysosomal dysfunction and impaired autophagic flux. Notably, TGF-β1 significantly reversed these changes. Our results suggested that TGF-β1 exerted neuroprotective effects on trauma- injured cortical neurons by reducing lysosomal dysfunction, decreasing the accumulation of autophagosomes and autophagolysosomes, and enhancing autophagic flux.

Experimental Models of Hospital-Acquired Infections After Traumatic Brain Injury: Challenges and Opportunities

Patients hospitalized after a moderate or severe traumatic brain injury (TBI) are at increased risk of nosocomial infections, including bacterial pneumonia and other upper respiratory tract infections. Infections represent a secondary immune challenge for vulnerable TBI patients that can lead to increased morbidity and poorer long-term prognosis. This review first describes the clinical significance of infections after TBI, delving into the known mechanisms by which a TBI can alter systemic immunological responses towards an immunosuppressive state, leading to promotion of increased vulnerability to infections. Pulmonary dysfunction resulting from respiratory tract infections is considered in the context of neurotrauma, including the bidirectional relationship between the brain and lungs. Turning to pre-clinical modeling, current laboratory approaches to study experimental TBI and lung infections are reviewed, to highlight findings from the limited key studies to date that have incorporated both insults. Then, practical decisions for the experimental design of animal studies of post-injury infections are discussed. Variables associated with the host animal, the infectious agent (e.g., species, strain, dose, and administration route), as well as the timing of the infection relative to the injury model are important considerations for model development. Together, the purpose of this review is to highlight the significant clinical need for increased pre-clinical research into the two-hit insult of a hospital-acquired infection after TBI to encourage further scientific enquiry in the field.

Pathophysiology of acute lung injury in patients with acute brain injury: the triple-hit hypothesis

It has been convincingly demonstrated in recent years that isolated acute brain injury (ABI) may cause severe dysfunction of peripheral extracranial organs and systems. Of all potential target organs and systems, the lung appears to be the most vulnerable to damage after ABI. The pathophysiology of the bidirectional brain-lung interactions is multifactorial and involves inflammatory cascades, immune suppression, and dysfunction of the autonomic system. Indeed, the systemic effects of inflammatory mediators in patients with ABI create a systemic inflammatory environment ("first hit") that makes extracranial organs vulnerable to secondary procedures that enhance inflammation, such as mechanical ventilation (MV), surgery, and infections ("second hit"). Moreover, accumulating evidence supports the knowledge that gut microbiota constitutes a critical superorganism and an organ on its own, potentially modifying various physiological functions of the host. Furthermore, experimental and clinical data suggest the existence of a communication network among the brain, gastrointestinal tract, and its microbiome, which appears to regulate immune responses, gastrointestinal function, brain function, behavior, and stress responses, also named the "gut-microbiome-brain axis." Additionally, recent research evidence has highlighted a crucial interplay between the intestinal microbiota and the lungs, referred to as the "gut-lung axis," in which alterations during critical illness could result in bacterial translocation, sustained inflammation, lung injury, and pulmonary fibrosis. In the present work, we aimed to further elucidate the pathophysiology of acute lung injury (ALI) in patients with ABI by attempting to develop the "double-hit" theory, proposing the "triple-hit" hypothesis, focused on the influence of the gut-lung axis on the lung. Particularly, we propose, in addition to sympathetic hyperactivity, blast theory, and double-hit theory, that dysbiosis and intestinal dysfunction in the context of ABI alter the gut-lung axis, resulting in the development or further aggravation of existing ALI, which constitutes the "third hit."

Immune regulation of the gut-brain axis and lung-brain axis involved in ischemic stroke

Local ischemia often causes a series of inflammatory reactions when both brain immune cells and the peripheral immune response are activated. In the human body, the gut and lung are regarded as the key reactional targets that are initiated by brain ischemic attacks. Mucosal microorganisms play an important role in immune regulation and metabolism and affect blood-brain barrier permeability. In addition to the relationship between peripheral organs and central areas and the intestine and lung also interact among each other. Here, we review the molecular and cellular immune mechanisms involved in the pathways of inflammation across the gut-brain axis and lung-brain axis. We found that abnormal intestinal flora, the intestinal microenvironment, lung infection, chronic diseases, and mechanical ventilation can worsen the outcome of ischemic stroke. This review also introduces the influence of the brain on the gut and lungs after stroke, highlighting the bidirectional feedback effect among the gut, lungs, and brain.

Creatinine Clearance in Acute Brain Injury: A Comparison of Methods

BACKGROUND

Currently, the measurement of glomerular filtration rate is very complex and costly, so its daily evaluation is performed using endogenous markers, of which creatinine is the most frequently used. It allows the estimation of glomerular filtration rate by means of its clearance or by formulas based on its serum and urine concentration. Augmented renal clearance (ARC) is frequent among critically ill patients and is defined as creatinine clearance (CrCl) > 130 ml/min/1.73 m2. The aim of this study was to compare measured CrCl (MCC) and estimated CrCl obtained with the Cockcroft-Gault formula (CG), the Modification of Diet in Renal Disease Study equation (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI) in patients with severe traumatic brain injury and nontraumatic subarachnoid hemorrhage. The second aim was to assess the incidence of ARC in this population of neurocritical patients.

METHODS

This was a prospective, observational, single center study from a cohort of 74 patients admitted to the neurocritical intensive care unit due to traumatic brain injury or subarachnoid hemorrhage. Serum creatinine (at 7 a.m.) and a 6-h urine collection were analyzed, and CrCl was measured and estimated by using CG, MDRD, and CKD-EPI. The intraclass correlation coefficient (ICC) was evaluated for each pair, and Bland-Altman plots were used to assess clinical significance.

RESULTS

Among 74 patients, the median age was 53 (interquartile range [IQR] 36-65), and the median Glasgow Coma Scale score at admission was 6. The median MCC at admission was 176 (IQR 135-214). The medians of CG, MDRD and CKD-EPI were, respectively, 129 ml/min/1.73 m2 (IQR 95-176), 158 (IQR 115-202), and 116 (97-132). An ICC was applied to evaluate the correlation between MCC and estimated methods and showed a weak correlation between MCC and estimated CrCl obtained with the three different methods. The strongest ICC statistical correlation was found between MCC and MDRD, and the weakest correlation was found between MCC and CKD-EPI. Bland-Altman plots showed that differences between each pair were not clinically acceptable. ARC was present in 78% of measurements, using MCC. A weak correlation was observed between MCC and calculated CrCl. CG, MDRD, and CKD-EPI overestimated MCC when MCC ≤ 130 ml/min/1.73 m2 and underestimated it when MCC > 130 ml/min/1.73 m2.

CONCLUSIONS

In this population, there was a weak statistical correlation between measured and estimated methods. In patients with ARC, formulas underestimated MCC. MCC should probably be the preferred methodology for renal function assessment in the clinical setting to better adjust drug dosage and guarantee drug effectiveness.

A Novel In Vitro Platform Development in the Lab for Modeling Blast Injury to Microglia

Traumatic brain injury (TBI), which is mainly caused by impact, often results in chronic neurological abnormalities. Since the pathological changes in vivo during primary biomechanical injury are quite complicated, the in-depth understanding of the pathophysiology and mechanism of TBI depends on the establishment of an effective experimental in vitro model. Usually, a bomb explosive blast was employed to establish the in vitro model, while the process is complex and unsuitable in the lab. Based on water-hammer, we have developed a device system to provide a single dynamic compression stress on living cells. A series of amplitude (∼5.3, ∼9.8, ∼13.5 MPa) were generated to explore the effects of dynamic compression loading on primary microglia within 48 h. Apoptosis experiments indicated that primary microglia had strong tolerance to blast waves. In addition, the generation of intercellular reactive oxygen species and secretory nitric oxide was getting strongly enhanced and recovered within 48 h. In addition, there is a notable release of pro-inflammatory cytokine by microglia. Our work provides a reproducible and peaceable method of loading single dynamic compression forces to cells in vitro. Microglia showed an acute inflammatory response to dynamic loadings, while no significant cell death was observed. This insight delivers a new technological approach that could open new areas to a better understanding of the mechanism of cell blast injuries.

Role of statins in regulating molecular pathways following traumatic brain injury: A system pharmacology study

Traumatic brain injury (TBI) is a serious disorder with debilitating physical and psychological complications. Previous studies have indicated that genetic factors have a critical role in modulating the secondary phase of injury in TBI. Statins have interesting pleiotropic properties such as antiapoptotic, antioxidative, and anti-inflammatory effects, which make them a suitable class of drugs for repurposing in TBI. In this study, we aimed to explore how statins modulate proteins and pathways involved in TBI using system pharmacology. We first explored the target associations with statins in two databases to discover critical clustering groups, candidate hub and critical hub genes in the network of TBI, and the possible connections of statins with TBI-related genes. Our results showed 1763 genes associated with TBI. Subsequently, the analysis of centralities in the PPI network displayed 55 candidate hub genes and 15 hub genes. Besides, MCODE analysis based on threshold score:10 determined four modular clusters. Intersection analysis of genes related to TBI and statins demonstrated 204 shared proteins, which suggested that statins influence 31 candidate hub and 9 hub genes. Moreover, statins had the highest interaction with MCODE1. The biological processes of the 31 shared proteins are related to gene expression, inflammation, antioxidant activity, and cell proliferation. Biological enriched pathways showed Programmed Cell Death proteins, AGE-RAGE signaling pathway, C-type lectin receptor signalling pathway, and MAPK signaling pathway as top clusters. In conclusion, statins could target several critical post-TBI genes mainly involved in inflammation and apoptosis, supporting the previous research results as a potential therapeutic agent.

TGF-β1 Protects Trauma-injured Murine Cortical Neurons by Upregulating L-type Calcium Channel Cav1.2 via the p38 Pathway

Traumatic brain injury (TBI) is a leading cause of disability and death in adolescents, and there is a lack of effective methods of treatment. The neuroprotective effects exerted by TGF-β1 can ameliorate a range of neuronal lesions in multiple central nervous system diseases. In this study, we used an in-vitro TBI model of mechanical injury on murine primary cortical neurons and the neuro-2a cell line to investigate the neuroprotective role played by TGF-β1 in cortical neurons in TBI. Our results showed that TGF-β1 significantly increased neuronal viability and inhibited apoptosis for 24 h after trauma. The expression of Ca_v1.2, an L-type calcium channel (LTCC) isoform, decreased significantly after trauma injury, and this change was reversed by TGF-β1. Nimodipine, a classic LTCC blocker, abolished the protective effect of TGF-β1 on trauma-induced neuronal apoptosis. The knockdown of Ca_v1.2 in differentiated neuro-2a cells significantly inhibited the anti-apoptosis effect of TGF-β1 exerted on injured neuro-2a cells. Moreover, TGF-β1 rescued and enhanced the trauma-suppressed neuro-2a intracellular Ca²⁺ concentration, while the effect of TGF-β1 was partially inhibited by nimodipine. TGF-β1 significantly upregulated the expression of Ca_v1.2 by activating the p38 MAPK pathway and by inhibiting trauma-induced neuronal apoptosis. In conclusion, TGF-β1 increased trauma-injured murine cortical neuronal activity and inhibited apoptosis by upregulating Cav1.2 channels via activating the p38 MAPK pathway. Therefore, the TGF-β1/p38 MAPK/Ca_v 1.2 pathway has the potential to be used as a novel therapeutic target for TBI.

Physiological and Pathophysiological Consequences of Mechanical Ventilation

Mechanical ventilation is a life-support system used to ensure blood gas exchange and to assist the respiratory muscles in ventilating the lung during the acute phase of lung disease or following surgery. Positive-pressure mechanical ventilation differs considerably from normal physiologic breathing. This may lead to several negative physiological consequences, both on the lungs and on peripheral organs. First, hemodynamic changes can affect cardiovascular performance, cerebral perfusion pressure (CPP), and drainage of renal veins. Second, the negative effect of mechanical ventilation (compression stress) on the alveolar-capillary membrane and extracellular matrix may cause local and systemic inflammation, promoting lung and peripheral-organ injury. Third, intra-abdominal hypertension may further impair lung and peripheral-organ function during controlled and assisted ventilation. Mechanical ventilation should be optimized and personalized in each patient according to individual clinical needs. Multiple parameters must be adjusted appropriately to minimize ventilator-induced lung injury (VILI), including: inspiratory stress (the respiratory system inspiratory plateau pressure); dynamic strain (the ratio between tidal volume and the end-expiratory lung volume, or inspiratory capacity); static strain (the end-expiratory lung volume determined by positive end-expiratory pressure [PEEP]); driving pressure (the difference between the respiratory system inspiratory plateau pressure and PEEP); and mechanical power (the amount of mechanical energy imparted as a function of respiratory rate). More recently, patient self-inflicted lung injury (P-SILI) has been proposed as a potential mechanism promoting VILI. In the present chapter, we will discuss the physiological and pathophysiological consequences of mechanical ventilation and how to personalize mechanical ventilation parameters.

Traumatic Brain Injury: Mechanisms of Glial Response

Traumatic brain injury (TBI) is a heterogeneous disorder that involves brain damage due to external forces. TBI is the main factor of death and morbidity in young males with a high incidence worldwide. TBI causes central nervous system (CNS) damage under a variety of mechanisms, including synaptic dysfunction, protein aggregation, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Glial cells comprise most cells in CNS, which are mediators in the brain’s response to TBI. In the CNS are present astrocytes, microglia, oligodendrocytes, and polydendrocytes (NG2 cells). Astrocytes play critical roles in brain’s ion and water homeostasis, energy metabolism, blood-brain barrier, and immune response. In response to TBI, astrocytes change their morphology and protein expression. Microglia are the primary immune cells in the CNS with phagocytic activity. After TBI, microglia also change their morphology and release both pro and anti-inflammatory mediators. Oligodendrocytes are the myelin producers of the CNS, promoting axonal support. TBI causes oligodendrocyte apoptosis, demyelination, and axonal transport disruption. There are also various interactions between these glial cells and neurons in response to TBI that contribute to the pathophysiology of TBI. In this review, we summarize several glial hallmarks relevant for understanding the brain injury and neuronal damage under TBI conditions.

Brain stem death induces pro-inflammatory cytokine production and cardiac dysfunction in sheep model

Introduction

Organs procured following brain stem death (BSD) are the main source of organ grafts for transplantation. However, BSD is associated with inflammatory responses that may damage the organ and affect both the quantity and quality of organs available for transplant. Therefore, we aimed to investigate plasma and bronchoalveolar lavage (BAL) pro-inflammatory cytokine profiles and cardiovascular physiology in a clinically relevant 6-h ovine model of BSD.

Methods

Twelve healthy female sheep (37–42 Kg) were anaesthetized and mechanically ventilated prior to undergoing BSD induction and then monitored for 6 h. Plasma and BAL endothelin-1 and cytokines (IL-1β, 6, 8 and tumour necrosis factor alpha (TNF-α)) were assessed by ELISA. Differential white blood cell counts were performed. Cardiac function during BSD was also examined using echocardiography, and cardiac biomarkers (A-type natriuretic peptide and troponin I were measured in plasma.

Results

Plasma concentrations big ET-1, IL-6, IL-8, TNF-α and BAL IL-8 were significantly (p < 0.01) increased over baseline at 6 h post-BSD. Increased numbers of neutrophils were observed in the whole blood (3.1 × 10⁹ cells/L [95% confidence interval (CI) 2.06–4.14] vs. 6 × 10⁹ cells/L [95%CI 3.92–7.97]; p < 0.01) and BAL (4.5 × 10⁹ cells/L [95%CI 0.41–9.41] vs. 26 [95%CI 12.29–39.80]; p = 0.03) after 6 h of BSD induction vs baseline. A significant increase in ANP production (20.28 pM [95%CI 16.18–24.37] vs. 78.68 pM [95%CI 53.16–104.21]; p < 0.0001) and cTnI release (0.039 ng/mL vs. 4.26 [95%CI 2.69–5.83] ng/mL; p < 0.0001), associated with a significant reduction in heart contractile function, were observed between baseline and 6 h.

Conclusions

BSD induced systemic pro-inflammatory responses, characterized by increased neutrophil infiltration and cytokine production in the circulation and BAL fluid, and associated with reduced heart contractile function in ovine model of BSD.

Brain-lung interactions and mechanical ventilation in patients with isolated brain injury

During the last decade, experimental and clinical studies have demonstrated that isolated acute brain injury (ABI) may cause severe dysfunction of peripheral extracranial organs and systems. Of all potential target organs and systems, the lung appears to be the most vulnerable to damage after brain injury (BI). The pathophysiology of these brain–lung interactions are complex and involve neurogenic pulmonary oedema, inflammation, neurodegeneration, neurotransmitters, immune suppression and dysfunction of the autonomic system. The systemic effects of inflammatory mediators in patients with BI create a systemic inflammatory environment that makes extracranial organs vulnerable to secondary procedures that enhance inflammation, such as mechanical ventilation (MV), surgery and infections. Indeed, previous studies have shown that in the presence of a systemic inflammatory environment, specific neurointensive care interventions—such as MV—may significantly contribute to the development of lung injury, regardless of the underlying mechanisms. Although current knowledge supports protective ventilation in patients with BI, it must be born in mind that ABI-related lung injury has distinct mechanisms that involve complex interactions between the brain and lungs. In this context, the role of extracerebral pathophysiology, especially in the lungs, has often been overlooked, as most physicians focus on intracranial injury and cerebral dysfunction. The present review aims to fill this gap by describing the pathophysiology of complications due to lung injuries in patients with a single ABI, and discusses the possible impact of MV in neurocritical care patients with normal lungs.

Acute Kidney Injury at the Neurocritical Care Unit

Neurocritical care has advanced substantially in recent decades, allowing doctors to treat patients with more complicated conditions who require a multidisciplinary approach to achieve better clinical outcomes. In neurocritical patients, nonneurological complications such as acute kidney injury (AKI) are independent predictors of worse clinical outcomes. Different research groups have reported an AKI incidence of 11.6% and an incidence of stage 3 AKI, according to the Kidney Disease: Improving Global Outcomes, that requires dialysis of 3% to 12% in neurocritical patients. These patients tend to be younger, have less comorbidity, and have a different risk profile, given the diagnostic and therapeutic procedures they undergo. Trauma-induced AKI, sepsis, sympathetic overstimulation, tubular epitheliopathy, hyperchloremia, use of nephrotoxic drugs, and renal hypoperfusion are some of the causes of AKI in neurocritical patients. AKI is the result of a sum of events, although the mechanisms underlying many of them remain uncertain; however, two important causes that merit mention are direct alteration of the physiological brain-kidney connection and exposure to injury as a result of the specific medical management and well-established therapies that neurocritical patients are subjected to. This review will focus on AKI in neurocritical care patients. Specifically, it will discuss its epidemiology, causes, associated mechanisms, and relationship to the brain-kidney axis. Additionally, the use and risks of extracorporeal therapies in this group of patients will be reviewed.

Beyond the Brain: Peripheral Interactions after Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability, and there are currently no pharmacological treatments known to improve patient outcomes. Unquestionably, contributing toward a lack of effective treatments is the highly complex and heterogenous nature of TBI. In this review, we highlight the recent surge of research that has demonstrated various central interactions with the periphery as a potential major contributor toward this heterogeneity and, in particular, the breadth of research from Australia. We describe the growing evidence of how extracranial factors, such as polytrauma and infection, can significantly alter TBI neuropathology. In addition, we highlight how dysregulation of the autonomic nervous system and the systemic inflammatory response induced by TBI can have profound pathophysiological effects on peripheral organs, such as the heart, lung, gastrointestinal tract, liver, kidney, spleen, and bone. Collectively, this review firmly establishes TBI as a systemic condition. Further, the central and peripheral interactions that can occur after TBI must be further explored and accounted for in the ongoing search for effective treatments.

Ability to regulate immunity of mesenchymal stem cells in the treatment of traumatic brain injury

Traumatic brain injury (TBI) is characterized by broad clinical symptoms in brain insult by external damages to the skull. TBI potentially leads to severe physical, cognitive, and emotional impairment. The complex biochemical reactions of inflammatory processes in TBI significantly influence brain function and clinical sequelae's overall severity. Mesenchymal stem cell therapy has become a promising therapeutic field of treatment for serious injuries due to its ability to regulate the inflammatory microenvironment. In this study, we aimed to investigate MSC's anti-inflammatory ability through regulating leukocyte, neutrophils, and inflammatory factors (IL-6, CRP, and TNF-a), thereby reducing the trauma in the TBI. Biological effects of autologous MNC and MSC cell transplantation have been studied in 40 patients with molded TBI, after being filtered according to appropriate criteria. All patients initially received MNCs and subsequently MSCs (both intravenously) followed by continuous monitoring during treatment (2 months) with clinical cognitive indicators. The results after transplantation MSC indicated that the majority of patients experienced improved health function in different degrees during the follow-up period. Lower serum levels of inflammatory factors, leukocytes, and neutrophils population were detected following the transplantation compared with the levels prior to treatment and with the control patients. No severe symptoms were observed in patients after transplantation, despite 3-4 death cases in each group. Overall, the present study suggests that transplantation of MSC possibly regulates inflammatory factors and appears to be safe in TBI treatment.

Brain-gut axis dysfunction in the pathogenesis of traumatic brain injury

Traumatic brain injury (TBI) is a chronic and progressive disease, and management requires an understanding of both the primary neurological injury and the secondary sequelae that affect peripheral organs, including the gastrointestinal (GI) tract. The brain-gut axis is composed of bidirectional pathways through which TBI-induced neuroinflammation and neurodegeneration impact gut function. The resulting TBI-induced dysautonomia and systemic inflammation contribute to the secondary GI events, including dysmotility and increased mucosal permeability. These effects shape, and are shaped by, changes in microbiota composition and activation of resident and recruited immune cells. Microbial products and immune cell mediators in turn modulate brain-gut activity. Importantly, secondary enteric inflammatory challenges prolong systemic inflammation and worsen TBI-induced neuropathology and neurobehavioral deficits. The importance of brain-gut communication in maintaining GI homeostasis highlights it as a viable therapeutic target for TBI. Currently, treatments directed toward dysautonomia, dysbiosis, and/or systemic inflammation offer the most promise.

Multipotential and systemic effects of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality of people at all ages. Biochemical, cellular and physiological events that occur during primary injury lead to a delayed and long-term secondary damage that can last from hours to years. Secondary brain injury causes tissue damage in the central nervous system and a subsequent strong and rapid inflammatory response that may lead to persistent inflammation. However, this inflammatory response is not limited to the brain. Inflammatory mediators are transferred from damaged brain tissue to the bloodstream and produce a systemic inflammatory response in peripheral organs, including the cardiovascular, pulmonary, gastrointestinal, renal and endocrine systems. Complications of TBI are associated with its multiple and systemic effects that should be considered in the treatment of TBI patients. Therefore, in this review, an attempt was made to examine the systemic effects of TBI in detail. It is hoped that this review will identify the mechanisms of injury and complications of TBI, and open a window for promising treatment in TBI complications.

A Histological and Morphometric Assessment of the Adult and Juvenile Rat Livers after Mild Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the most severe problems of modern medicine that plays a dominant role in morbidity and mortality in economically developed countries. Our experimental study aimed to evaluate the histological and morphological changes occurring in the liver of adult and juvenile mildly traumatized rats (mTBI) in a time-dependent model. The experiment was performed on 70 adult white rats at three months of age and 70 juvenile rats aged 20 days. The mTBI was modelled by the Impact-Acceleration Model-free fall of weight in the parieto-occipital area. For histopathological comparison, the samples were taken on the 1st, 3rd, 5th, 7th, 14th, and 21st days after TBI. In adult rats, dominated changes in the microcirculatory bed in the form of blood stasis in sinusoidal capillaries and veins, RBC sludge, and adherence to the vessel wall with the subsequent appearance of perivascular and focal leukocytic infiltrates. In juvenile rats, changes in the parenchyma in the form of hepatocyte dystrophy prevailed. In both groups, the highest manifestation of the changes was observed on 5–7 days of the study. On 14–21 days, compensatory phenomena prevailed in both groups. Mild TBI causes changes in the liver of both adult and juvenile rats. The morphological pattern and dynamics of liver changes, due to mild TBI, are different in adult and juvenile rats.

Ethanol Intoxication Alleviates the Inflammatory Response of Remote Organs to Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) may cause damage to distant organs. Acute ethanol intoxication (EI) induces complex local and systemic anti-inflammatory effects and influences the early outcomes of traumatized patients. Here, we evaluated its effects on the BI-induced expression of local inflammatory mediators in the trauma-remote organs the lungs and liver. Male mice were exposed to ethanol as a single oral dose (5g·kg^–1, 32%) before inducing a moderate blunt TBI. Sham groups underwent the same procedures without TBI. Ether 3 or 6h after the TBI, the lung and liver were collected. The gene expression of HMGB1, IL-6, MMP9, IL-1β, and TNF as well as the homogenate protein levels of receptor for advanced glycation end products (RAGE), IL-6, IL-1β, and IL-10 were analyzed. Liver samples were immunohistologically stained for HMGB1. EI decreased the gene expressions of the proinflammatory markers HMGB1, IL-6, and MMP9 in the liver upon TBI. In line with the reduced gene expression, the TBI-induced protein expression of IL-6 in liver tissue homogenates was significantly reduced by EI at 3h after TBI. While the histological HMGB1 expression was enhanced by TBI, the RAGE protein expression in the liver tissue homogenates was diminished after TBI. EI reduced the histological HMGB1 expression and enhanced the hepatic RAGE protein expression at 6h post TBI. With regard to the lungs, EI significantly reduced the gene expressions of HMGB1, IL-6, IL-1β, and TNF upon TBI, without significantly affecting the protein expression levels of inflammatory markers (RAGE, IL-6, IL-1β, and IL-10). At the early stage of TBI-induced inflammation, the gene expression of inflammatory mediators in both the lungs and liver is susceptible to ethanol-induced remote effects. Taken together, EI may alleviate the TBI-induced pro-inflammatory response in the trauma-distant organs, the lungs and liver, via the HMGB1-RAGE axis.

Modulating neuroinflammation and oxidative stress to prevent epilepsy and improve outcomes after traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability in young adults worldwide. TBI survival is associated with persistent neuropsychiatric and neurological impairments, including posttraumatic epilepsy (PTE). To date, no pharmaceutical treatment has been found to prevent PTE or ameliorate neurological/neuropsychiatric deficits after TBI. Brain trauma results in immediate mechanical damage to brain cells and blood vessels that may never be fully restored given the limited regenerative capacity of brain tissue. This primary insult unleashes cascades of events, prominently including neuroinflammation and massive oxidative stress that evolve over time, expanding the brain injury, but also clearing cellular debris and establishing homeostasis in the region of damage. Accumulating evidence suggests that oxidative stress and neuroinflammatory sequelae of TBI contribute to posttraumatic epileptogenesis. This review will focus on possible roles of reactive oxygen species (ROS), their interactions with neuroinflammation in posttraumatic epileptogenesis, and emerging therapeutic strategies after TBI. We propose that inhibitors of the professional ROS-generating enzymes, the NADPH oxygenases and myeloperoxidase alone, or combined with selective inhibition of cyclooxygenase mediated signaling may have promise for the treatment or prevention of PTE and other sequelae of TBI. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Crosstalk between brain, lung and heart in critical care

Extracerebral complications, especially pulmonary and cardiovascular, are frequent in brain-injured patients and are major outcome determinants. Two major pathways have been described: brain-lung and brain-heart interactions. Lung injuries after acute brain damages include ventilator-associated pneumonia (VAP), acute respiratory distress syndrome (ARDS) and neurogenic pulmonary œdema (NPE), whereas heart injuries can range from cardiac enzymes release, ECG abnormalities to left ventricle dysfunction or cardiogenic shock. The pathophysiologies of these brain-lung and brain-heart crosstalk are complex and sometimes interconnected. This review aims to describe the epidemiology and pathophysiology of lung and heart injuries in brain-injured patients with the different pathways implicated and the clinical implications for critical care physicians.

Bioinformatic analysis of brain-specific miRNAs for identification of candidate traumatic brain injury blood biomarkers

BACKGROUND

Detection of brain-specific miRNAs in the peripheral blood could serve as a surrogate marker of traumatic brain injury (TBI). Here, we systematically identified brain-enriched miRNAs, and tested their utility as TBI biomarkers in the acute phase of care.

METHODS

Publically available microarray data generated from 29 postmortem human tissues were used to rank 1,364 miRNAs in terms of their degree of brain-specific expression. Levels of the top six ranked miRNAs were then prospectively measured in serum samples collected from 10 Patients with TBI at hospital admission, as well as from 10 controls.

RESULTS

The top six miRNAs identified in our analysis (miR-124-3p, miR-219a-5p, miR-9-5p, miR-9-3p, miR-137, and miR-128-3p) were enriched 70 to 320-fold in brain relative to other tissues, and exhibited dramatically greater brain specificity compared to several miRNAs previously proposed as biomarkers. Furthermore, their levels were elevated in serum from patients with TBI compared to controls, and could collectively discriminate between groups with 90% sensitivity and 100% specificity. Interestingly, subsequent informatic pathway analysis revealed that their target transcripts were enriched for components of signaling pathways active in peripheral organs involved in common post-TBI complications.

CONCLUSIONS

The six candidate miRNAs identified in this preliminary study have promise as blood biomarkers of TBI, and could also be molecular contributors to systemic physiologic changes commonly observed post-injury.

Hypozincaemia is associated with severity of aneurysmal subarachnoid haemorrhage: a retrospective cohort study

BACKGROUND

Hypozincaemia may develop in critically ill patients, including those with acute brain injury in the early phase after hospital admission. The aim of this study was to investigate the prevalence of hypozincaemia after aneurysmal subarachnoid haemorrhage (aSAH) and its association with delayed cerebral ischemia and functional outcome.

METHODS

We retrospectively analysed a cohort of 384 patients with SAH admitted to the Neurointensive Care Unit at Rigshospitalet, Copenhagen, Denmark, in whom at least one measurement of plasma zinc concentration was done during the hospital stay. Hypozincaemia was defined as at least one measurement of plasma zinc below 10 μmol/L. Potential associations between hypozincaemia, demographic variables and functional outcome after aSAH were analysed in multivariable logistic regression models.

RESULTS

Hypozincaemia was observed in 67% (n = 257) of all patients and occurred within 7 days in more than 95% of all hypozincaemic patients. In a multivariable model, severe SAH (WFNS 3-5; OR 4.2, CI 2.21-8.32, p < 0.001) and Sequential Organ Failure Assessment (SOFA) score on the day of admission (OR 1.24, CI 1.11-1.40, p < 0.001) were independently associated with hypozincaemia. In another multivariable model, hypozincaemia was independently associated with an unfavourable outcome (defined as a modified Rankin Scale score from 3 to 6) (OR 1.97, CI 1.06-3.68, p = 0.032), as was age (OR 1.03, CI 1.01-1.05, p = 0.015), SOFA score on the day of admission (OR 1.14, CI 1.02-1.29, p = 0.02), a diagnosis of delayed cerebral ischaemia (OR 4.06, CI 2.29-7.31, p < 0.001) and a clinical state precluding assessment for delayed cerebral ischaemia (OR 15.13, CI 6.59-38.03, p < 0.001).

CONCLUSION

Hypozincaemia occurs frequently after aSAH, is associated with a higher disease severity and independently contributes to an unfavourable outcome.

Lung injury in brain ischemia/reperfusion is exacerbated by mechanical ventilation with moderate tidal volume in rats

Ischemic stroke is one of the most frequent causes of injury in the central nervous system which may lead to multiorgan dysfunction, including in the lung. The aim of this study was to investigate whether brain ischemia/reperfusion with or without mechanical ventilation leads to lung injury. Male Sprague-Dawley rats were assigned to four groups: Sham, 1-h brain ischemia (MCAO)/24-h reperfusion (I/R), mechanical ventilation with moderate tidal volume (MTV), and I/R+MTV. The pulmonary capillary permeability (K_fc) was measured in the isolated perfused lung. Mean arterial blood pressure (MAP), heart rate (HR), blood-gas variables, histopathological parameters, lung glutathione peroxidase, and TNF-α were measured. K_fc in the I/R, MTV, and I/R+MTV groups were higher than that in the Sham group. In the I/R, MTV, and I/R+MTV groups, arterial partial pressures of oxygen and the arterial partial pressure of oxygen/fraction of inspired oxygen ratios were lower, whereas arterial partial pressures of carbon dioxide were higher than those in the Sham group. The histopathological score in the I/R group was more than that in the Sham group, and in the MTV and I/R+MTV groups were higher than those in the Sham and I/R groups. Furthermore, there were stepwise rises in TNF-α in the I/R, MTV, and I/R+MTV groups, respectively. There was no significant difference in MAP between groups. However, HR in the MTV group was higher than that in the Sham group. Brain ischemia/reperfusion leads to pulmonary capillary endothelial damage and the impairment of gas exchange in the alveolar-capillary barrier, which is exacerbated by mechanical ventilation with moderate tidal volume partially linked to inflammatory reactions.

IMPACT probability of poor outcome and plasma cytokine concentrations are associated with multiple organ dysfunction syndrome following traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) is a major cause of morbidity and mortality. Multiple organ dysfunction syndrome (MODS) occurs frequently after TBI and independently worsens outcome. The present study aimed to identify potential admission characteristics associated with post-TBI MODS.

METHODS

The authors performed a secondary analysis of a recent randomized clinical trial studying the effects of erythropoietin and blood transfusion threshold on neurological recovery after TBI. Admission clinical, demographic, laboratory, and imaging parameters were used in a multivariable Cox regression analysis to identify independent risk factors for MODS following TBI, defined as maximum total Sequential Organ Failure Assessment (SOFA) score > 7 within 10 days of TBI.

RESULTS

Two hundred patients were initially recruited and 166 were included in the final analysis. Respiratory dysfunction was the most common nonneurological organ system dysfunction, occurring in 62% of the patients. International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) probability of poor outcome at admission was significantly associated with MODS following TBI (odds ratio [OR] 8.88, 95% confidence interval [CI] 1.94-42.68, p < 0.05). However, more commonly used measures of TBI severity, such as the Glasgow Coma Scale, Injury Severity Scale, and Marshall classification, were not associated with post-TBI MODS. In addition, initial plasma concentrations of interleukin (IL)-6, IL-8, and IL-10 were significantly associated with the development of MODS (OR 1.47, 95% CI 1.20-1.80, p < 0.001 for IL-6; OR 1.26, 95% CI 1.01-1.58, p = 0.042 for IL-8; OR 1.77, 95% CI 1.24-2.53, p = 0.002 for IL-10) as well as individual organ dysfunction (SOFA component score ≥ 1). Finally, MODS following TBI was significantly associated with mortality (OR 5.95, 95% CI 2.18-19.14, p = 0.001), and SOFA score was significantly associated with poor outcome at 6 months (Glasgow Outcome Scale score < 4) when analyzed as a continuous variable (OR 1.21, 95% CI 1.06-1.40, p = 0.006).

CONCLUSIONS

Admission IMPACT probability of poor outcome and initial plasma concentrations of IL-6, IL-8, and IL-10 were associated with MODS following TBI.

Augmented Renal Clearance

Augmented renal clearance (ARC) is a phenomenon in critically ill patients characterized by increased creatinine clearance and elimination of renally eliminated medications. Patients with severe neurologic injury, sepsis, trauma, and burns have been consistently identified as at risk of ARC, with mean creatinine clearances ranging from 170 ml/minute to more than 300 ml/minute. Several potential mechanisms may contribute to the occurrence of ARC including endogenous responses to increased metabolism and solute production, alterations in neurohormonal balance, and therapeutic maneuvers such as fluid resuscitation. Augmented renal clearance is associated with suboptimal exposure to critical medications, including β-lactams and vancomycin, increasing the risk of treatment failure. Although definitive screening tools are not yet known, critical care pharmacists must be vigilant in recognizing when ARC may be a contributing factor affecting expected treatment outcomes in individual patients. Optimizing dosing strategies in critically ill patients with ARC remains a goal of continued research. The current review discusses the clinical characteristics and methods of identifying patients at risk of ARC, potential mechanisms for ARC, and describes pharmacotherapy dosing considerations in patients with ARC.

Role of Methylprednisolone in the Management of Hemodynamically Unstable Brain-Dead Cases

OBJECTIVES

Optimal care of potential donors can lead to successful transplantation. Hemodynamic instability is a common complication in deceased potential donors. The most common underlying causes are hormonal and electrolyte disturbances as well as a hyperinflammatory state, which is rooted in activation of the cytokine cascade. In this study, our aim was to evaluate the efficacy of methylprednisolone injection, an agent introduced for inflammation suppression to achieve more stability in cases of hemodynamic disturbances.

MATERIALS AND METHODS

This study covered the period from April 2016 to June 2017 and included 45 randomly selected hemodynamically unstable brain-dead cases (mean arterial pressure < 60 mm Hg). For these cases, primary management included trying to achieve stability; however, after many hours, we experienced hemodynamic instability again. Because of no other correctable methods, we decided to use methylprednisolone injection. The potential deceased donors received a total of 1 g methylprednisolone in two 500-mg divided doses after transfer to the organ procurement unit.

RESULTS

Of 45 patients, 26 were male (58%), and the mean age of patients was 33 years. The most common causes of brain death were trauma (33%) and cerebrovascular accident (22%). Systolic and diastolic blood pressures increased significantly after methylprednisolone use. We observed no significant dif ferences in pulse rate. In addition, methylprednisolone could correct pH from 7.33 ± 0.11 to 7.38 ± 0.12 (P = .007).

CONCLUSIONS

Use of methylprednisolone in hemodynamically unstable deceased donors could allow better management of these cases. Because there are various factors such as infusion of vasopressor drugs or fluid therapy that could affect the hemodynamic status of these cases, future studies with larger sample sizes are recommended to control these confounding factors.

Lung Ultrasound as a Bedside Tool for Assessment of Extravascular Lung Water in Critically Ill Head Injured Patients: An Observational Study

Introduction

Extra vascular lung water (EVLW) is defined as the amount of fluid in the interstitial and alveolar spaces. Primary aim of this study was to assess EVLW using lung USG (B lines >3 per lung field) in critically ill head injured patients.

Materials and methods

Intubated adult patients admitted in Trauma ICU with head injury (GCS 4-15) were assessed by daily chest X-ray and lung ultrasonography. Lung water content was graded based on the number of B lines per ICS with score ranging from 0-32 and categorized as low pulmonary fluid burden (0-10), moderate fluid burden (11-20) and high fluid burden (21-32).

Results

140 critically ill head injured patients were assessed for eligibility and 20 excluded. Incidence of increased EVLW using lung USG was 61.66% (74/120) and the incidence reported using chest x ray was 40.83%(49/120) and the difference was statistically significant (p value <0.001). Increased EVLW significantly increased the duration of weaning, mechanical ventilation and ICU stay (p value <0.05). Significant association was observed between APACHE II, SAPS II and GCS at admission to ICU with presence of EVLW (p value ≤0.001). Mean delay in identification of EVLW by chest X-ray (CXR) compared to lung ultrasound was 1.42±0.76 days.

Conclusion

Lung ultrasound is better than CXR for early detection of increased EVLW in critically ill head injured patients and has prognostic relevance as increased EVLW prolongs duration of mechanical ventilation and ICU stay.

How to cite this article

Gattupalli V, Jain K, et al. Lung Ultrasound as a Bedside Tool for Assessment of Extravascular Lung Water in Critically Ill Head Injured Patients: An Observational Study. Indian J Crit Care Med 2019;23(3):131-134.

Pulmonary Complications After Spontaneous Aneurysmal Subarachnoid Hemorrhage: Experience from Barrow Neurological Institute

OBJECTIVE

Because the clinical course of spontaneous aneurysmal subarachnoid hemorrhage (aSAH) can be compromised by pulmonary complications, we sought to review posttreatment outcomes in aSAH patients with and without pulmonary complications.

METHODS

Patient demographic, clinical, and outcome data (March 2003-January 2007) were analyzed retrospectively. Patients underwent microsurgical or endovascular treatment for aSAH; pulmonary complications were reported. Outcomes were assessed using the Glasgow Outcome Scale (GOS) scores at the 1-year, 3-year, and 6-year follow-up visits.

RESULTS

The cohort comprised 471 patients (mean age, 53.7 ± 12.4 years; men, 332/471 [70%]). The mean Glasgow Coma Scale (GCS) score at presentation was 11.9 ± 3.0. Of 471 patients, 47% (n = 223) presented with a Hunt and Hess score of ≥3 and 76% (n = 357) with a Fisher grade of 3. Treatment was clipping for 69% (279/407) and coiling for 31% (128/407) of patients. Pulmonary complications occurred in 210 of 471 (45%) patients. Nearly one-half of patients were discharged to home (215/471, 46%), and more than one-half had a good outcome defined as a GOS score of 5 at their 1-year (226/403, 56%), 3-year (217/397, 55%), and 6-year (203/380, 53%) follow-up visits. Logistic regression showed age and GCS scores as outcome predictors at all time points, whereas pulmonary complications predicted poor outcome only at the 1-year follow-up visit.

CONCLUSIONS

Pulmonary problems represent the most common nonneurologic medical complications after aSAH. Despite advances in critical care, pulmonary complications represented predictors of short-term poor outcome only at the 1-year follow-up visit, whereas the medical history of the patient became more relevant for prognosis in long-term follow-up.

Effect of hypertonic saline in the pretreatment of lung donors with hemorrhagic shock

BACKGROUND

Hemorrhagic shock-induced lung edema and inflammation are two of the main reasons for the rejection of lungs donated for transplantation. Hypertonic saline (HS) induces intravascular volume expansion and has considerable immunomodulating effects that might minimize edema. Our hypothesis is based on the use of a hypertonic solution for treatment of donors who are in shock in an attempt to increase the supply of lungs for transplantation.

METHODS

A total of 80 rats were allocated to four groups: one group was given an infusion of normal saline (NS; n = 20), one group received HS; n = 20, a sham group (n = 20), and a Shock group (n = 20). Half of the lungs from each group were evaluated in an ex vivo perfusion system, and the other half was used for measurements of cytokine levels and neutrophil counts.

RESULTS

In the ex vivo perfusion assessment, the pulmonary artery pressures of the animals in the NS and HS groups did not exhibit significant differences compared with those in the sham group (P > 0.05) but were lower than those in the Shock group (P < 0.01). Furthermore, the tumor necrosis factor-α levels and neutrophil counts were lower in the HS group than those in the Shock group (P < 0.01) and did not exhibit significant differences compared with those in either the NS and Sham groups (P > 0.05).

CONCLUSIONS

We showed that HS was equivalent to isotonic saline and contributed to the treatment of lungs subjected to hemorrhagic shock.

Peripheral Inflammation and Demyelinating Diseases

In recent decades, several neurodegenerative diseases have been shown to be exacerbated by systemic inflammatory processes. There is a wide range of literature that demonstrates a clear but complex relationship between the central nervous system (CNS) and the immunological system, both under naïve or pathological conditions. In diseased brains, peripheral inflammation can transform "primed" microglia into an "active" state, which can trigger stronger pathological responses. Demyelinating diseases are a group of neurodegenerative diseases characterized by inflammatory lesions associated with demyelination, which in turn induces axonal damage, neurodegeneration, and progressive loss of function. Among them, the most important are multiple sclerosis (MS) and neuromyelitis optica (NMO). In this review, we will analyze the effect of specific peripheral inflammatory stimuli in the progression of demyelinating diseases and discuss their animal models. In most cases, peripheral immune stimuli are exacerbating.

Neuropulmonology

Neuropulmonology refers to the complex interconnection between the central nervous system and the respiratory system. Neurologic injury includes traumatic brain injury, hemorrhage, stroke, and seizures, and in each there are far-reaching effects that can result in pulmonary dysfunction. Systemic changes can induce impairment of pulmonary function due to changes in the core structure and function of the lung. The conditions and disorders that often occur in these patients include aspiration pneumonia, neurogenic pulmonary edema, and acute respiratory distress syndrome, but also several abnormal respiratory patterns and sleep-disordered breathing. Lung infections, pulmonary edema - neurogenic or cardiogenic - and pulmonary embolus all are a serious barrier to recovery and can have significant effects on outcomes such as hospital course, prognosis, and mortality. This review presents the spectrum of pulmonary abnormalities seen in neurocritical care.

Peptide Pharmacological Approaches to Treating Traumatic Brain Injury: a Case for Arginine-Rich Peptides

Traumatic brain injury (TBI) has a devastating effect on victims and their families, and has profound negative societal and economic impacts, a situation that is further compounded by the lack of effective treatments to minimise injury after TBI. The current strategy for managing TBI is partly through preventative measures and partly through surgical and rehabilitative interventions. Secondary brain damage remains the principal focus for the development of a neuroprotective therapeutic. However, the complexity of TBI pathophysiology has meant that single-action pharmacological agents have been largely unsuccessful in combatting the associated brain injury cascades, while combination therapies to date have proved equally ineffective. Peptides have recently emerged as promising lead agents for the treatment of TBI, especially those rich in the cationic amino acid, arginine. Having been shown to lessen the impact of ischaemic stroke in animal models, there are reasonable grounds to believe that arginine-rich peptides may have neuroprotective therapeutic potential in TBI. Here, we review a range of peptides previously examined as therapeutic agents for TBI. In particular, we focus on cationic arginine-rich peptides -- a new class of agents that growing evidence suggests acts through multiple neuroprotective mechanisms.

Neuroprotection Trials in Traumatic Brain Injury

Traumatic brain injury (TBI) is a significant cause of mortality and morbidity worldwide. Current treatment of acute TBI includes surgical intervention when needed, followed by supportive critical care such as optimizing cerebral perfusion, preventing pyrexia, and treating raised intracranial pressure. While effective in managing the primary injury to the brain and skull, these treatment modalities do not address the complex secondary cascades that occur at a cellular level following initial injury and greatly affect the ultimate neurologic outcome. These secondary processes involve changes in ionic flux, disruption of cellular function, derangement of blood flow and the blood-brain barrier, and elevated levels of free radicals. Over the past few decades, numerous pharmacologic agents and modalities have been investigated in an attempt to interrupt these secondary processes. No neuroprotective agents currently exist that have been proven to improve neurologic outcome following TBI. However, these trials have contributed significantly to the understanding of the clinical sequelae of TBI and to improvements in the quality of care for TBI. With the experience and insights that have been accrued with the trials to date, we will be able to optimize future trial designs and refine established neurologic endpoints to better identify new therapeutic agents and further improve neurologic outcomes from this often devastating condition.

Comparison of the pharmacokinetics of vancomycin in neurosurgical and non-neurosurgical patients

Although vancomycin concentrations in neurosurgical patients tend to be lower following standard dosing compared with other patient populations, factors influencing vancomycin pharmacokinetics in neurosurgical patients are poorly understood. In this study, pharmacokinetic (PK) parameters in neurosurgical and non-neurosurgical patients were compared. Furthermore, factors influencing vancomycin PK alterations, including those known to augment renal clearance, were determined. Routine therapeutic drug monitoring data from neurosurgical and non-neurosurgical patients were retrospectively collected. Vancomycin PK parameters were estimated using non-linear mixed-effects modelling (NONMEM v.7.2.0); analyses were performed for the entire population and for neurosurgical patients only. Furthermore, the final models performed a bootstrap, visual predictive check and external validation. A total of 359 serum vancomycin concentration data variables from 132 patients were used to execute the PK modelling. Neurosurgical patient factor, the early phase of treatment, underlying liver cirrhosis, co-administration of a nephrotoxic drug and estimated creatinine clearance influenced vancomycin clearance (CL). However, other factors known to augment renal clearance did not affect vancomycin pharmacokinetics. Vancomycin CL was significantly higher in neurosurgical patients than in controls (0.104 ± 0.036 L/h/kg vs. 0.073 ± 0.042 L/h/kg; P <0.01). Augmented vancomycin CL should be considered when determining vancomycin dosages in neurosurgical patients.

Increased Risk of Post-Trauma Stroke after Traumatic Brain Injury-Induced Acute Respiratory Distress Syndrome

This study determines whether acute respiratory distress syndrome (ARDS) is an independent risk factor for an increased risk of post-traumatic brain injury (TBI) stroke during 3-month, 1-year, and 5-year follow-ups, respectively, after adjusting for other covariates. Clinical data for the analysis were from the National Health Insurance Database 2000, which covered a total of 2121 TBI patients and 101 patients with a diagnosis of TBI complicated with ARDS (TBI-ARDS) hospitalized between January 1, 2001 and December 31, 2005. Each patient was tracked for 5 years to record stroke occurrences after discharge from the hospital. The prognostic value of TBI-ARDS was evaluated using a multivariate Cox proportional hazard model. The main outcome found that stroke occurred in nearly 40% of patients with TBI-ARDS, and the hazard ratio for post-TBI stroke increased fourfold during the 5-year follow-up period after adjusting for other covariates. The increased risk of hemorrhagic stroke in the ARDS group was considerably higher than in the TBI-only cohort. This is the first study to report that post-traumatic ARDS yielded an approximate fourfold increased risk of stroke in TBI-only patients. We suggest intensive and appropriate medical management and intensive follow-up of TBI-ARDS patients during the beginning of the hospital discharge.

Kidney-brain link in traumatic brain injury patients? A preliminary report

BACKGROUND

Kidney hyperfiltration with augmented renal clearance is frequently observed in patients with traumatic brain injury. The aim of this study is to report preliminary findings about the relationship between brain autoregulation impairment, estimated kidney glomerular filtration rate and outcome in critically ill patients after severe traumatic brain injury.

METHODS

Data collected from a cohort of 18 consecutive patients with severe traumatic brain injury managed with ICP monitoring in a Neurocritical Care Unit, were retrospectively analyzed. Early morning blood tests were performed for routine chemistry assessments and we analyzed creatinine and estimated creatinine clearance, osmolarity, and sodium. Daily norepinephrine dose, protein intake, and water balance were documented. Time average of brain monitoring data (intracranial pressure, cerebral perfusion pressure, and cerebrovascular reactivity pressure index--PRx) were calculated for 6 h before blood sample tests. Patient outcome was evaluated using Glasgow outcome scale at 6-month follow-up, considering nonfatal outcome if GOS ≥ 3 and fatal outcome if GOS < 3. Multiple linear regression models were used to study the crude and adjusted effects of the above variables on PRx throughout time.

RESULTS

A total of 199 complete daily observations from 18 adult consecutive multiple trauma patients with severe traumatic brain injury were analyzed. At hospital admission, the median post-resuscitation Glasgow coma score was 6 (range 3-12), mean SAPSII score was 44.65 with predicted mortality of 36 %. Hospital mortality rate was 27 % and median GOS at 6 month after discharge was 3. Creatinine clearance (CrCl) was found to have a negative correlation with PRx (Pearson correlation--0.82), with statistically significant crude (p < 0.001) and adjusted (p = 0.001) effects. For each increase of 10 ml/min in CrCl (estimated either by the Cockcroft-Gault or by Modification of Diet in Renal Disease Study equations) a mean decrease in PRx of approximately 0.01 was expected. Amongst possible confounders only norepinephrine was shown to have a significant effect. Mean PRx value for outcome fatal status was greater than mean PRx for nonfatal status (p < 0.05), regardless of the model used for the CrCl estimation.

CONCLUSIONS

Better cerebral autoregulation evaluated with cerebrovascular PRx is significantly correlated with augmented renal clearance in TBI patients and associates with better outcome.

Neuronal Cell Death Induced by Mechanical Percussion Trauma in Cultured Neurons is not Preceded by Alterations in Glucose, Lactate and Glutamine Metabolism

Traumatic brain injury (TBI) is a devastating neurological disorder that usually presents in acute and chronic forms. Brain edema and associated increased intracranial pressure in the early phase following TBI are major consequences of acute trauma. On the other hand, neuronal injury, leading to neurobehavioral and cognitive impairments, that usually develop months to years after single or repetitive episodes of head trauma, are major consequences of chronic TBI. The molecular mechanisms responsible for TBI-induced injury, however, are unclear. Recent studies have suggested that early mitochondrial dysfunction and subsequent energy failure play a role in the pathogenesis of TBI. We therefore examined whether oxidative metabolism of (13)C-labeled glucose, lactate or glutamine is altered early following in vitro mechanical percussion-induced trauma (5 atm) to neurons (4-24 h), and whether such events contribute to the development of neuronal injury. Cell viability was assayed using the release of the cytoplasmic enzyme lactate dehydrogenase (LDH), together with fluorescence-based cell staining (calcein and ethidium homodimer-1 for live and dead cells, respectively). Trauma had no effect on the LDH release in neurons from 1 to 18 h. However, a significant increase in LDH release was detected at 24 h after trauma. Similar findings were identified when traumatized neurons were stained with fluorescent markers. Additionally (13)C-labeling of glutamate showed a small, but statistically significant decrease at 14 h after trauma. However, trauma had no effect on the cycling ratio of the TCA cycle at any time-period examined. These findings indicate that trauma does not cause a disturbance in oxidative metabolism of any of the substrates used for neurons. Accordingly, such metabolic disturbance does not appear to contribute to the neuronal death in the early stages following trauma.

Brain-lung crosstalk: Implications for neurocritical care patients

Major pulmonary disorders may occur after brain injuries as ventilator-associated pneumonia, acute respiratory distress syndrome or neurogenic pulmonary edema. They are key points for the management of brain-injured patients because respiratory failure and mechanical ventilation seem to be a risk factor for increased mortality, poor neurological outcome and longer intensive care unit or hospital length of stay. Brain and lung strongly interact via complex pathways from the brain to the lung but also from the lung to the brain. Several hypotheses have been proposed with a particular interest for the recently described “double hit” model. Ventilator setting in brain-injured patients with lung injuries has been poorly studied and intensivists are often fearful to use some parts of protective ventilation in patients with brain injury. This review aims to describe the epidemiology and pathophysiology of lung injuries in brain-injured patients, but also the impact of different modalities of mechanical ventilation on the brain in the context of acute brain injury.

CD11d integrin blockade reduces the systemic inflammatory response syndrome after traumatic brain injury in rats

Traumatic CNS injury triggers a systemic inflammatory response syndrome (SIRS), in which circulating inflammatory cells invade body organs causing local inflammation and tissue damage. We have shown that the SIRS caused by spinal cord injury is greatly reduced by acute intravenous treatment with an antibody against the CD11d subunit of the CD11d/CD18 integrin expressed by neutrophils and monocyte/macrophages, a treatment that reduces their efflux from the circulation. Traumatic brain injury (TBI) is a frequently occurring injury after motor vehicle accidents, sporting and military injuries, and falls. Our studies have shown that the anti-CD11d treatment diminishes brain inflammation and oxidative injury after moderate or mild TBI, improving neurological outcomes. Accordingly, we examined the impact of this treatment on the SIRS triggered by TBI. The anti-CD11d treatment was given at 2h after a single moderate (2.5-3.0 atm) or 2 and 24h after each of three consecutive mild (1.0-1.5 atm) fluid percussion TBIs. Sham-injured, saline-treated rats served as controls. At 24h, 72 h, and 4 or 8 weeks after the single TBI and after the third of three TBIs, lungs of rats were examined histochemically, immunocytochemically and biochemically for downstream effects of SIRS including inflammation, tissue damage and expression of oxidative enzymes. Lung sections revealed that both the single moderate and repeated mild TBI caused alveolar disruption, thickening of inter-alveolar tissue, hemorrhage into the parenchyma and increased density of intra-and peri-alveolar macrophages. The anti-CD11d treatment decreased the intrapulmonary influx of neutrophils and the density of activated macrophages and the activity of myeloperoxidase after these TBIs. Moreover, Western blotting studies showed that the treatment decreased lung protein levels of oxidative enzymes gp91(phox), inducible nitric oxide synthase and cyclooxygenase-2, as well as the apoptotic pathway enzyme caspase-3 and levels of 4-hydroxynonenal-bound proteins (an indicator of lipid peroxidation). Decreased expression of the cytoprotective transcription factor Nrf2 reflected decreased lung oxidative stress. Anti-CD11d treatment also diminished the lung concentration of free radicals and tissue aldehydes. In conclusion, the substantial lung component of the SIRS after single or repeated TBIs is significantly decreased by a simple, minimally invasive and short-lasting anti-inflammatory treatment.

Brain death and marginal grafts in liver transplantation

It is well known that most organs for transplantation are currently procured from brain-dead donors; however, the presence of brain death is an important risk factor in liver transplantation. In addition, one of the mechanisms to avoid the shortage of liver grafts for transplant is the use of marginal livers, which may show higher risk of primary non-function or initial poor function. To our knowledge, very few reviews have focused in the field of liver transplantation using brain-dead donors; moreover, reviews that focused on both brain death and marginal grafts in liver transplantation, both being key risk factors in clinical practice, have not been published elsewhere. The present review aims to describe the recent findings and the state-of-the-art knowledge regarding the pathophysiological changes occurring during brain death, their effects on marginal liver grafts and summarize the more controversial topics of this pathology. We also review the therapeutic strategies designed to date to reduce the detrimental effects of brain death in both marginal and optimal livers, attempting to explain why such strategies have not solved the clinical problem of liver transplantation.

Hyperbaric oxygen effects on neuronal apoptosis associations in a traumatic brain injury rat model

BACKGROUND

The neuroprotective mechanisms of hyperbaric oxygen (HBO) therapy on traumatic brain injury (TBI) remain unclear, especially neuronal apoptosis associations such as the expression of tumor necrosis factor alpha (TNF-α), transforming growth-interacting factor (TGIF), and TGF-β1 after TBI. The aim of this study was to investigate the neuroprotective effects of HBO therapy in a rat model of TBI.

MATERIALS AND METHODS

The experimental rats were randomly divided into three groups as follows: TBI + normobaric air (21% O₂ at one absolute atmosphere), TBI + HBO, and sham-operated normobaric air. The TBI + HBO rats received 100% O₂ at 2.0 absolute atmosphere for 1 h immediately after TBI. Local and systemic TNF-α expression, neuropathology, levels of the neuronal apoptosis-associated proteins TGIF and TGF-β1, and functional outcome were evaluated 72 h after the onset of TBI.

RESULTS

Compared to the TBI control groups, the running speed of rats on the TreadScan after TBI was significantly attenuated by HBO therapy. The TBI-induced local and systemic TNF-α expression, neuronal damage score, and neuronal apoptosis were also significantly reduced by HBO therapy. Moreover, HBO treatment attenuated the expression of TGIF but increased TGF-β1 expression in neurons.

CONCLUSIONS

We concluded that treatment of TBI with HBO during the acute phase of injury can decrease local and systemic proinflammatory cytokine TNF-α production, resulting in neuroprotective effects. We also suggest that decreased levels of TGIF and increased levels of TGF-β in the injured cortex leading to decreased neuronal apoptosis is one mechanism by which functional recovery may occur.

Neurotrophins, cytokines, oxidative parameters and funcionality in Progressive Muscular Dystrophies

We investigated the levels of brain derived-neurotrophic factor (BDNF), cytokines and oxidative parameters in serum and tried to correlate them with the age and functionality of patients with Progressive Muscle Dystrophies (PMD). The patients were separated into six groups (case and controls pared by age and gender), as follows: Duchenne Muscular Dystrophy (DMD); Steinert Myotonic Dystrophy (SMD); and Limb-girdle Muscular Dystrophy type-2A (LGMD2A). DMD patients (± 17.9 years old) had a decrease of functionality, an increase in the IL-1β and TNF-α levels and a decrease of IL-10 levels and superoxide dismutase activity in serum. SMD patients (± 25.8 years old) had a decrease of BDNF and IL-10 levels and superoxide dismutase activity and an increase of IL-1β levels in serum. LGMD2A patients (± 27.7 years old) had an decrease only in serum levels of IL-10. This research showed the first evidence of BDNF involvement in the SMD patients and a possible unbalance between pro-inflammatory and anti-inflammatory cytokine levels, along with decreased superoxide dismutase activity in serum of DMD and SMD patients.

Systemic manifestations of traumatic brain injury

Traumatic brain injury (TBI) affects functioning of various organ systems in the absence of concomitant non-neurologic organ injury or systemic infection. The systemic manifestations of TBI can be mild or severe and can present in the acute phase or during the recovery phase. Non-neurologic organ dysfunction can manifest following mild TBI or severe TBI. The pathophysiology of systemic manifestations following TBI is multifactorial and involves an effect on the autonomic nervous system, involvement of the hypothalamic-pituitary axis, release of inflammatory mediators, and treatment modalities used for TBI. Endocrine dysfunction, electrolyte imbalance, and respiratory manifestations are common following TBI. The influence of TBI on systemic immune response, coagulation cascade, cardiovascular system, gastrointestinal system, and other systems is becoming more evident through animal studies and clinical trials. Systemic manifestations can independently act as risk factors for mortality and morbidity following TBI. Some conditions like neurogenic pulmonary edema and disseminated intravascular coagulation can adversely affect the outcome. Early recognition and treatment of systemic manifestations may improve the clinical outcome following TBI. Further studies are required especially in the field of neuroimmunology to establish the role of various biochemical cascades, not only in the pathophysiology of TBI but also in its systemic manifestations and outcome.

Hypothermia at 35 °C reduces the time-dependent microglial production of pro-inflammatory and anti-inflammatory factors that mediate neuronal cell death

BACKGROUND

Therapeutic hypothermia protects neurons after severe brain damage. This effect has been mainly achieved at the core temperatures of 32-34 °C; however, the optimum temperature of therapeutic hypothermia is not fully defined. Here we studied whether hypothermic culture at 35 °C had the same effects on the decrease of time-dependent expression of tumor necrosis factor (TNF)-α, interleukin (IL)-10, and nitric oxide (NO) by stimuli-activated microglia as that at 33 °C, as determined in our previous reports, and whether these factors directly induced neuronal cell death.

METHODS

We determined the levels of cytokines and NO produced by microglia cultured with adenosine triphosphate (ATP), a toll-like receptor (TLR)2 agonist (N-palmitoyl-S-(2,3-bis(palmitoyloxy)-(2R,S)-propyl)-(R)-cysteinyl-seryl-(lysyl)3-lysine, Pam(3)CSK(4)), or a TLR4 agonist (lipopolysaccharide) under mild hypothermic (33 °C), minimal hypothermic (35 °C), and normothermic (37 °C) conditions. We also determined the viability of rat neuronal pheochromocytoma PC12 cells treated with recombinant TNF-α or IL-10 or (±)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR3, an NO donor).

RESULTS

Production of TNF-α, as well as that of IL-10 and NO were decreased by minimal hypothermia at 1.5-6, and 24-48 h, respectively, compared with normothermia, although some effects were diminished as compared with those by mild hypothermia. Exposure to TNF-α, IL-10, and NOR3 caused the death of PC12 cells in a concentration-dependent manner after 24 h.

CONCLUSION

Hypothermic culture at 35 °C decreased the production of early-phase TNF-α and late-phase IL-10 and NO from ATP- and TLR-activated microglia as observed at 33 °C, albeit with diminished effects. Moreover, these factors caused the death of neuronal cells in a concentration-dependent manner. These results suggest that the attenuation of microglial production of TNF-α, IL-10, and NO by therapeutic hypothermia leads to the inhibition of neuronal cell death. Minimal hypothermia at 35 °C may be sufficient to elicit neuroprotective effect.