Immune enhancing nutrition in traumatic brain injury - A preliminary study

Probiotics in Traumatic Brain Injury: New Insights into Mechanisms and Future Perspectives

Traumatic brain injury (TBI) is a serious global public health issue, recognized as a chronic and progressive disease that can affect multiple organs, including the gastrointestinal (GI) tract. Research shows that there is a specific link between the GI tract and the central nervous system, termed the gut-brain axis, which consists of bidirectional exchange between these two. Several preclinical and clinical studies have demonstrated intestinal barrier dysfunction, intestinal inflammation and gut dysbiosis in patients with TBI. It is proven that probiotics can modulate the inflammatory process and modify gut microbiota. Numerous animal studies and human clinical trials have proven the effectiveness of selected bacterial strains as an adjuvant treatment in reducing inflammation, infection rates and time spent in intensive care of hospitalized patients suffering from brain injury. Thus, this review summarizes the current evidence regarding the beneficial effects of probiotic administration in patients suffering from TBI-related complications. This review will help identify novel therapeutic strategies in the future as probiotics have an extensive history of apparently safe use.

Bifidobacteria in disease: from head to toe

Bifidobacteria as a strictly anaerobic gram-positive bacteria, is widely distributed in the intestine, vagina and oral cavity, and is one of the first gut flora to colonize the early stages of life. Intestinal flora is closely related to health, and dysbiosis of intestinal flora, especially Bifidobacteria, has been found in a variety of diseases. Numerous studies have shown that in addition to maintaining intestinal homeostasis, Bifidobacteria may be involved in diseases covering all parts of the body, including the nervous system, respiratory system, genitourinary system and so on. This review collects evidence for the variation of Bifidobacteria in typical diseases among various systems, provides mild and effective therapeutic options for those diseases that are difficult to cure, and moves Bifidobacteria from basic research to further clinical applications.

Gut microbiota and traumatic central nervous system injuries: Insights into pathophysiology and therapeutic approaches

Traumatic brain injury and spinal cord injury are two distinct but fundamentally similar types of acute insults to the central nervous system (CNS) that often culminate in death or cognitive and motor impairment. Over the past decade, researchers have tapped into research to discover the potential role being played by gut bacteria in CNS. After an acute CNS injury, the altered composition of the gut microbiota disturbs the balance of the bidirectional gut-brain axis, aggravating secondary CNS injury, motor dysfunctions, and cognitive deficits, which worsens the patient's prognosis. Some of the well-known therapeutic interventions which can also be used as adjuvant therapy for alleviating CNS injuries include, the use of pro and prebiotics, fecal microbiota transplantation, and microbial engineering. In this review, we aim to discuss the importance of gut microbes in our nervous system, anatomy, and signaling pathways involved in regulating the gut-brain axis, the alteration of the gut microbiome in CNS injuries, and the therapeutic strategies to target gut microbiomes in traumatic CNS injuries.

Optimization of Nutrition after Brain Injury: Mechanistic and Therapeutic Considerations

Emerging science continues to establish the detrimental effects of malnutrition in acute neurological diseases such as traumatic brain injury, stroke, status epilepticus and anoxic brain injury. The primary pathological pathways responsible for secondary brain injury include neuroinflammation, catabolism, immune suppression and metabolic failure, and these are exacerbated by malnutrition. Given this, there is growing interest in novel nutritional interventions to promote neurological recovery after acute brain injury. In this review, we will describe how malnutrition impacts the biomolecular mechanisms of secondary brain injury in acute neurological disorders, and how nutritional status can be optimized in both pediatric and adult populations. We will further highlight emerging therapeutic approaches, including specialized diets that aim to resolve neuroinflammation, immunodeficiency and metabolic crisis, by providing pre-clinical and clinical evidence that their use promotes neurologic recovery. Using nutrition as a targeted treatment is appealing for several reasons that will be discussed. Given the high mortality and both short- and long-term morbidity associated with acute brain injuries, novel translational and clinical approaches are needed.

Vitamin D: Can Gender Medicine Have a Role?

This narrative review aims to shed light on the role of gender differences, on the biological and molecular functions in the main pathological mechanisms that recognize the role of vitamin D. Vitamin D deficiency is widespread worldwide, but it is still very controversial whether the amount of vitamin D taken daily is actually the only problem related to its biological functions. Currently, the plasma concentration of 25-hydroxyvitamin D represents the only indicator of the circulating blood quota. The concept is that the biological function of vitamin D is not only linked to its circulating levels, but it is hypothesized that its biological functions depend, above all, on its total bioavailability. In particular, vitamin D circulates for the most part linked to albumin and vitamin D binding protein (DBP), which depend on various pathological conditions and physiologically, above all, the function of the latter is regulated by estrogens, glucocorticoids, and inflammatory cytokines. During her life, women undergo various changes in the hormonal and sexual sphere concerning menarche, possible pregnancies, and breastfeeding but also the use of contraceptives and, finally, the transition from the period of fertility to menopause. Each of these phases presents specific needs and, consequently, sometimes also specific criticalities. Studies on young women have shown that vitamin D deficiency is present in 58 to 91% of cases. Obesity, metabolic disorders, and variation in estrogen contraction may affect vitamin D deficiency due to the decreased bioavailability from dietary sources due to deposition in body fat compartments.

Effect of a collagen-enriched beverage with or without omega-3 fatty acids on wound healing, metabolic biomarkers, and adipokines in patients with major burns

BACKGROUND & AIMS

This study investigated the effects of collagen hydrolysate and omega-3 fatty acids (FAs) on the rate and quality of wound healing, metabolic disorders, and adipose-derived peptides in patients with major burns.

METHODS

In this randomized clinical trial, 66 patients with 20-45% deep partial or full-thickness burns were randomly assigned to three groups to receive either a beverage containing collagen (40 gr/d), collagen (40 gr/d) plus 3 gr/d omega-3 (ω-3) FAs, or placebo for four weeks. Wound healing rate, Vancouver scar scale (VSS), as well as baseline, weeks two and three serum concentrations of adiponectin, fibroblast growth factor 21 (FGF21), neuregulin 4 (NRG4), transforming growth factor (TGF)-β1, and pre-albumin/hs-CRP ratio were assessed.

RESULTS

The wound healing rate during the weeks post-burn (p = 0.006 and p = 0.01), and days of 95% (21.3 ± 6.8 and 22.9 ± 8.7 vs. 34.3 ± 14.8 days, p = 0.003 and p = 0.03) and complete (26 ± 7.7 and 27.4 ± 9.4 vs. 41.1 ± 16.6 days, p = 0.003 and p = 0.01) wound healing were significantly better with Collagen and Collagen. ω-3 compared to the placebo group. The VSS was significantly lower, indicated better scar status, in the both intervention groups compared to the placebo (p = 0.02 and p = 0.01). Wound healing outcomes were not statistically different between the Collagen and Collagen. ω-3 groups. Hs-CRP/pre-albumin ratio was significantly lower in the Collagen. ω-3 than the placebo group at week three (1.2 ± 1.9 vs. 4.8 ± 7.7 dl/l, p = 0.03). The significant decrease in serum adiponectin seen during the trial course within the placebo (10 ± 8.8 to 5.8 ± 4.9 mg/l, p = 0.03) and Collagen (11.8 ± 14 to 8.6 ± 11.7 mg/l, p = 0.03) groups was prevented in the Collagen. ω-3 group (p = 0.4). Circulating FGF21 decreased significantly within the Collagen (p = 0.005) and Collagen. ω-3 (p = 0.02) groups at the end of week three compared to the baseline.

CONCLUSIONS

Adding collagen hydrolysate as part of adjunctive therapy improved wound healing rate and quality. These findings as well as the efficacy of omega-3 FAs need to be further confirmed in larger populations. This study was registered with the Iranian Registry of Clinical Trials (IRCT20090901002394N42).

The Brain–Gut Axis in Traumatic Brain Injury: Implications for Nutrition Support

Purpose of Review

Early enteral nutrition improves outcomes following traumatic brain injury (TBI). This can prove difficult due to TBI-induced feeding intolerance secondary to disruption of the brain-gut axis, a network composed of central nervous system (CNS) input, autonomic signaling, and immunologic regulation that controls gut and CNS homeostasis. Here, we discuss the pathophysiology of brain–gut axis dysregulation and outline nutrition strategies in patients with TBI.

Recent Findings

Feeding intolerance following TBI is multifactorial; complex signaling between the CNS, sympathetic nervous system, parasympathetic nervous system, and enteric nervous system that controls gut homeostasis is disrupted within hours post-injury. This has profound effects on the immune system and gut microbiome, further complicating post-TBI recovery. Despite this disruption, calorie and protein requirements increase considerably following TBI, and early nutritional supplementation improves survival following TBI. Enteral nutrition has proven more efficacious than parenteral nutrition in TBI patients and should be initiated within 48 hours following admission. Immune-fortified nutrition reduces CNS and gut inflammation and may improve outcomes in TBI patients.

Summary

Although autonomic dysregulation of the brain–gut axis results in feeding intolerance following TBI, early enteral nutrition is of paramount importance. Enteral nutrition reduces post-TBI inflammation and enhances immunologic and gut function. When feasible, enteral nutrition should be initiated within 48 hours following injury.

Gastrointestinal Microbiome and Neurologic Injury

Communication between the enteric nervous system (ENS) of the gastrointestinal (GI) tract and the central nervous system (CNS) is vital for maintaining systemic homeostasis. Intrinsic and extrinsic neurological inputs of the gut regulate blood flow, peristalsis, hormone release, and immunological function. The health of the gut microbiome plays a vital role in regulating the overall function and well-being of the individual. Microbes release short-chain fatty acids (SCFAs) that regulate G-protein-coupled receptors to mediate hormone release, neurotransmitter release (i.e., serotonin, dopamine, noradrenaline, γ-aminobutyric acid (GABA), acetylcholine, and histamine), and regulate inflammation and mood. Further gaseous factors (i.e., nitric oxide) are important in regulating inflammation and have a response in injury. Neurologic injuries such as ischemic stroke, spinal cord injury, traumatic brain injury, and hemorrhagic cerebrovascular lesions can all lead to gut dysbiosis. Additionally, unfavorable alterations in the composition of the microbiota may be associated with increased risk for these neurologic injuries due to increased proinflammatory molecules and clotting factors. Interventions such as probiotics, fecal microbiota transplantation, and oral SCFAs have been shown to stabilize and improve the composition of the microbiome. However, the effect this has on neurologic injury prevention and recovery has not been studied extensively. The purpose of this review is to elaborate on the complex relationship between the nervous system and the microbiome and to report how neurologic injury modulates the status of the microbiome. Finally, we will propose various interventions that may be beneficial in the recovery from neurologic injury.

Relationship between mild traumatic brain injury and the gut microbiome: A scoping review

There is increasing evidence for the important role of gut microbiota (GMB) in the development and progression of neurologic pathologies. Some studies have shown that modifying the microbiome profile can confer benefits to patients. Mild traumatic brain injury (mTBI) is a common occurrence in the general population. Although most patients recover, in a minority, disabling symptoms can persist for several months. We carried out a review of the literature to assess the effect of mTBI on GMB and to determine whether alleviating dysbiosis can improve clinical outcomes in mTBI patients. We performed searches in Medline/PubMed and Embase using the keywords "MTBI" AND "microbiome" OR "microbiota". Additional articles were identified by manual searches and using the Google search engine. In animal models, a clear perturbation of GMB was reported following TBI and probiotic supplementation (Lactobacillus acidophilus or Clostridium butyricum) improved neurologic function. There were no studies on changes in GMB after mTBI in humans; however, pre- or probiotic supplementation reduced the infection rate in patients with severe TBI and shortened the time spent in the intensive care unit without conferring any neurologic benefits. Thus, although the findings from animal models are promising, clinical studies are needed to determine whether therapeutic strategies that restore gut microbiome profile can improve long-term outcomes of patients with mTBI.

Beneficial Effect of Immune-Enhanced Enteral Nutrition on Immune Function in Patients With Severe Neurological Diseases: A Single-Center Randomized Controlled Trial

Background: Undernutrition is the main reason for the use of artificial nutrition in patients with severe neurological diseases. However, the clinical and immunological outcomes of enteral nutrition supplemented with immunomodulatory nutrients in these patients remain unclear.

Methods: In this single-center, randomized controlled study, 57 patients with severe neurological diseases were randomly divided into the following two groups according to the type of enteral nutrition they would receive: immune-enhancing (IE) (n = 27) and non-IE (NIE) (n = 30). The IE and NIE groups received enteral nutrition supplemented with immunomodulatory nutrients and standard enteral nutrition, respectively. We compared the nutritional status and the state of cellular immunity between the patients of the two groups. Clinical and immunological variables were evaluated following nutritional treatment.

Results: Feeding intolerance was lower in the IE than that in the NIE group (P = 0.04). However, there were no significant differences between the results of the two groups in terms of length of stay in the intensive care unit or hospital, extubation time, or body mass index (P > 0.05). The CD4+ T-lymphocyte count and CD4⁺/CD8+ ratio in the peripheral blood increased significantly in the IE group. The expression of CD28 activated cell surface markers was higher in the IE than in the NIE group. In addition, increased plasma interferon-γ levels were recorded in the IE group, whereas the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-8, and IL-10 decreased.

Conclusions: Immune-enhanced enteral nutrition could improve the immune status and feeding tolerance in patients with severe neurological diseases.

Trial Registration:www.chictr.org.cn/index.aspx, identifier: ChiCTR-IPR-17013909.

Inflammation in Traumatic Brain Injury

There is an increasing evidence that inflammation contributes to clinical and functional outcomes in traumatic brain injury (TBI). Many successful target-engaging, lesion-reducing, symptom-alleviating, and function-improving interventions in animal models of TBI have failed to show efficacy in clinical trials. Timing and immunological context are paramount for the direction, quality, and intensity of immune responses to TBI and the resulting neuroanatomical, clinical, and functional course. We present components of the immune system implicated in TBI, potential immune targets, and target-engaging interventions. The main objective of our article is to point toward modifiable molecular and cellular mechanisms that may modify the outcomes in TBI, and contribute to increasing the translational value of interventions that have been identified in animal models of TBI.

Does modern research validate the ancient wisdom of gut flora and brain connection? A literature review of gut dysbiosis in neurological and neurosurgical disorders over the last decade

The connection between gastrointestinal microbiota and the brain has been described in ancient medical texts and is now well established by research. It is a bidirectional communication which plays a critical role in regulating not only the gastrointestinal homeostasis but has also been linked to higher emotional and cognitive functions. Recent studies have sought to expand on this concept by providing concrete evidence of the influence of gut microbiome on a wide array of diseases and disorders of the central nervous system. This article reviews the most recent literature published on this subject, over the previous decade and aims to establish the role of a healthy gut microbiome and probiotics as an effective adjunct in health and management of diseases of the nervous system. A literature search on PubMed database was conducted using keywords including "gut brain-axis," "gut dysbiosis," "neuropsychiatric disorders," "neurodegenerative disorders," "probiotic," and "traumatic brain injury." The search was performed without any publication date restrictions. Both animal and human studies evaluating the role of gut dysbiosis on various neurological and neurosurgical diseases, published in peer-reviewed journals, were reviewed. Current studies do not provide conclusive evidence of a direct origin of CNS disorders from gut dysbiosis, but a possible modulatory role of gut microbiota in certain neurological disorders has been implicated. An understanding of this connection can aid in finding novel therapeutic strategies for the management of neurological disorders associated with memory dysfunctions and brain and spinal cord injuries.

Clinical observation of individualized nutritional formula on inflammation index, immune status and gastrointestinal tolerance in patients with severe head injury

Objectives:

To evaluate the clinical significance of individualized nutritional formulas on inflammatory factors, immune status and gastrointestinal tolerance in patients with severe head injury.

Methods:

A total of 80 patients with severe head injury who were hospitalized in Baoding No.1 Central Hospital from March 2017 to March 2020 were randomly divided into two groups with 40 cases in each group. Patients in both groups were given enteral nutrition (EN), the control group was given conventional enteral nutrition formula through nasointestinal tube, and the experimental group was given individualized nutrition formula. All patients were tested for tumor necrosis factor(TNF-α), C-reactive protein(CRP), interleukin 6(IL-6), IgA, IgM, IgG, serum intestinal fatty acid binding protein(I-FABP) and D-lactic acid concentration before and after enteral nutrition treatment. The incidence of adverse reactions such as abdominal distension, diarrhea, constipation, and gastric retention within seven days after treatment of two groups were compared and analyzed.

Results:

There was no significant difference in inflammatory factors such as TNF-a, CRP, IL-6, immunoglobulin levels, I-FABP and D-lactic acid concentration between the two groups before treatment (p>0.05). After treatment, the above indicators of the two groups of patients were better than before treatment, the difference was statistically significant (p<0.05), and the experimental group was significantly better than the control group (p<0.05). The experimental group had a gastrointestinal adverse reaction rate of 10%, and the control group had 27.5%, the difference was statistically significant (p=0.04).

Conclusions:

Individualized nutritional formula has more significant advantages than conventional nutritional formula for patients with severe head injury, which can reduce inflammatory response, increase the patient’s immune level, improve the intestinal mucosal barrier function, have good gastrointestinal tolerance, and have a low incidence of adverse reactions.

Immunonutrition for traumatic brain injury in children and adolescents: protocol for a systematic review and meta-analysis

INTRODUCTION

Traumatic brain injury (TBI) is the leading cause of paediatric trauma death and disability worldwide. The 'Guidelines for the Management of Severe Traumatic Brain Injury (Fourth Edition)' recommend that nutritional goals should be achieved within 5-7 days of injury. Immune-enhancing nutrition or immunonutrition, referring to the addition of specialised nutrients, including glutamine, alanine, omega-3 fatty acids and nucleotides, to standard nutrition formulas, may improve surgical outcomes in the perioperative period. However, the role of immune-enhancing nutritional supplements for patients with paediatric TBI remains unclear. We will conduct a systematic review to determine the efficacy and safety of immunonutrition for patients with paediatric TBI and provide evidence for clinical decision-making.

METHODS AND ANALYSIS

Studies reporting immune-enhancing nutrition treatments for patients with paediatric TBI will be included. Outcomes of interest include the length of hospital stay, wound infections, all-cause mortality, non-wound infection, including pneumonia, urinary tract infection and bacteraemia, and the reports adverse events. Duration of follow-up has no restriction. Primary studies consisting of randomised controlled trials (RCTs) and non-RCTs will be eligible for this review, and only studies published in English will be included. We will search the Medline, Embase and Cochrane Library databases from their inception dates to January 2020. We will also search clinicaltrials.gov and the WHO International Clinical Trials Registry Platform for additional information. Two reviewers will independently select studies and extract data. Risk-of-bias will be assessed with tools based on the Cochrane risk-of-bias criteria and Newcastle-Ottawa Quality Assessment Scale. A meta-analysis will be used to pool data when there are sufficient studies with homogeneity. Heterogeneity of the estimates across studies will be assessed; if necessary, a subgroup analysis will be performed to explore the source of heterogeneity. The Grades of Recommendation, Assessment, Development and Evaluation method will be applied to assess the level of evidence obtained from this systematic review.

ETHICS AND DISSEMINATION

The proposed systematic review and meta-analysis will be based on published data, and thus ethical approval is not required. The results of this review will be published.

PROSPERO REGISTRATION NUMBER

CRD42020154814.

Nutrition Therapy, Glucose Control, and Brain Metabolism in Traumatic Brain Injury: A Multimodal Monitoring Approach

The goal of neurocritical care in patients with traumatic brain injury (TBI) is to prevent secondary brain damage. Pathophysiological mechanisms lead to loss of body mass, negative nitrogen balance, dysglycemia, and cerebral metabolic dysfunction. All of these complications have been shown to impact outcomes. Therapeutic options are available that prevent or mitigate their negative impact. Nutrition therapy, glucose control, and multimodality monitoring with cerebral microdialysis (CMD) can be applied as an integrated approach to optimize systemic immune and organ function as well as adequate substrate delivery to the brain. CMD allows real-time bedside monitoring of aspects of brain energy metabolism, by measuring specific metabolites in the extracellular fluid of brain tissue. Sequential monitoring of brain glucose and lactate/pyruvate ratio may reveal pathologic processes that lead to imbalances in supply and demand. Early recognition of these patterns may help individualize cerebral perfusion targets and systemic glucose control following TBI. In this direction, recent consensus statements have provided guidelines and recommendations for CMD applications in neurocritical care. In this review, we summarize data from clinical research on patients with severe TBI focused on a multimodal approach to evaluate aspects of nutrition therapy, such as timing and route; aspects of systemic glucose management, such as intensive vs. moderate control; and finally, aspects of cerebral metabolism. Research and clinical applications of CMD to better understand the interplay between substrate supply, glycemic variations, insulin therapy, and their effects on the brain metabolic profile were also reviewed. Novel mechanistic hypotheses in the interpretation of brain biomarkers were also discussed. Finally, we offer an integrated approach that includes nutritional and brain metabolic monitoring to manage severe TBI patients.

The sex-specific interaction of the microbiome in neurodegenerative diseases

Several neurologic diseases exhibit different prevalence and severity in males and females, highlighting the importance of understanding the influence of biologic sex and gender. Beyond host-intrinsic differences in neurologic development and homeostasis, evidence is now emerging that the microbiota is an important environmental factor that may account for differences between men and women in neurologic disease. The gut microbiota is composed of trillions of bacteria, archaea, viruses, and fungi, that can confer benefits to the host or promote disease. There is bidirectional communication between the intestinal microbiota and the brain that is mediated via immunologic, endocrine, and neural signaling pathways. While there is substantial interindividual variation within the microbiota, differences between males and females can be detected. In animal models, sex-specific microbiota differences can affect susceptibility to chronic diseases. In this review, we discuss the ways in which neurologic diseases may be regulated by the microbiota in a sex-specific manner.

Growing literature but limited evidence: A systematic review regarding prebiotic and probiotic interventions for those with traumatic brain injury and/or posttraumatic stress disorder

Traumatic brain injury (TBI) is highly prevalent among a wide range of populations, including civilians, military personnel, and Veterans. TBI sequelae may be further exacerbated by symptoms associated with frequently occurring comorbid psychiatric conditions, including posttraumatic stress disorder (PTSD). This is particularly true among the population of military personnel from recent conflicts in Iraq and Afghanistan, with a history of mild TBI (mTBI) and PTSD. The need for efficacious treatments for TBI and comorbid PTSD is significant, and evidence-based interventions for these frequently co-occurring conditions are limited. Based on findings suggesting that inflammation may be an underlying mechanism of both conditions, anti-inflammatory/immunoregulatory agents, including probiotics, may represent a novel strategy to treat TBI and/or PTSD-related symptoms. The focus of this systematic review was to identify and evaluate existing research regarding prebiotic and probiotic interventions for the populations of individuals with a history of TBI and/or PTSD. Only 4 studies were identified (3 severe TBI, 1 PTSD, 0 co-occurring TBI and PTSD). Although findings suggested some promise, work in this area is nascent and results to date do not support some claims within the extensive coverage of probiotics in the popular press.

Effects of immunonutrition on biomarkers in traumatic brain injury patients in Malaysia: a prospective randomized controlled trial

Background

Head injury is one of the top three diagnosis leading to intensive care unit (ICU) admission in Malaysia. There has been growing interest in using immunonutrition as a mode of modulating the inflammatory response to injury or infection with the aim of improving clinical outcome. The aim of the present study was to evaluate the effect of an immunonutrition on biomarkers (IL-6, glutathione, CRP, total protein and albumin) in traumatic brain injury patients.

Methods

Thirty six patients with head injury admitted to neurosurgical ICU in University Malaya Medical Centre were recruited for this study, over a 6-month period from July 2014 to January 2015. Patients were randomized to receive either an immunonutrition (Group A) or a standard (Group B) enteral feed. Levels of biomarkers were measured at day 1, 5 and 7 of enteral feeding.

Results

Patients in Group A showed significant reduction of IL-6 at day 5 (p < 0.001) with concurrent rise in glutathione levels (p = 0.049). Patients in Group A also demonstrated a significant increase of total protein level at the end of the study (day 7).

Conclusion

These findings indicate the potential of immunonutrition reducing cytokines and increasing antioxidant indices in patients with TBI. However, further studies incorporating patient outcomes are needed to determine its overall clinical benefits.

Trial registration

National Medical Research Register (NMRR) ID: 14–1430-23,171. ClinicalTrials.gov identifier: NCT03166449.

Acquired Amino Acid Deficiencies: A Focus on Arginine and Glutamine

Nonessential amino acids are synthesized de novo and therefore not diet dependent. In contrast, essential amino acids must be obtained through nutrition since they cannot be synthesized internally. Several nonessential amino acids may become essential under conditions of stress and catabolic states when the capacity of endogenous amino acid synthesis is exceeded. Arginine and glutamine are 2 such conditionally essential amino acids and are the focus of this review. Low arginine bioavailability plays a pivotal role in the pathogenesis of a growing number of varied diseases, including sickle cell disease, thalassemia, malaria, acute asthma, cystic fibrosis, pulmonary hypertension, cardiovascular disease, certain cancers, and trauma, among others. Catabolism of arginine by arginase enzymes is the most common cause of an acquired arginine deficiency syndrome, frequently contributing to endothelial dysfunction and/or T-cell dysfunction, depending on the clinical scenario and disease state. Glutamine, an arginine precursor, is one of the most abundant amino acids in the body and, like arginine, becomes deficient in several conditions of stress, including critical illness, trauma, infection, cancer, and gastrointestinal disorders. At-risk populations are discussed together with therapeutic options that target these specific acquired amino acid deficiencies.

Vitamins and nutrients as primary treatments in experimental brain injury: Clinical implications for nutraceutical therapies

With the numerous failures of pharmaceuticals to treat traumatic brain injury in humans, more researchers have become interested in combination therapies. This is largely due to the multimodal nature of damage from injury, which causes excitotoxicity, oxidative stress, edema, neuroinflammation and cell death. Polydrug treatments have the potential to target multiple aspects of the secondary injury cascade, while many previous therapies focused on one particular aspect. Of specific note are vitamins, minerals and nutrients that can be utilized to supplement other therapies. Many of these have low toxicity, are already FDA approved and have minimal interactions with other drugs, making them attractive targets for therapeutics. Over the past 20 years, interest in supplementation and supraphysiologic dosing of nutrients for brain injury has increased and indeed many vitamins and nutrients now have a considerable body of the literature backing their use. Here, we review several of the prominent therapies in the category of nutraceutical treatment for brain injury in experimental models, including vitamins (B2, B3, B6, B9, C, D, E), herbs and traditional medicines (ginseng, Gingko biloba), flavonoids, and other nutrients (magnesium, zinc, carnitine, omega-3 fatty acids). While there is still much work to be done, several of these have strong potential for clinical therapies, particularly with regard to polydrug regimens. This article is part of a Special Issue entitled SI:Brain injury and recovery.