Interventional vitamin C: A strategy for attenuation of coagulopathy and inflammation in a swine multiple injuries model

Vitamin C as Scavenger of Reactive Oxygen Species during Healing after Myocardial Infarction

Currently, coronary artery bypass and reperfusion therapies are considered the gold standard in long-term treatments to restore heart function after acute myocardial infarction. As a drawback of these restoring strategies, reperfusion after an ischemic insult and sudden oxygen exposure lead to the exacerbated synthesis of additional reactive oxidative species and the persistence of increased oxidation levels. Attempts based on antioxidant treatment have failed to achieve an effective therapy for cardiovascular disease patients. The controversial use of vitamin C as an antioxidant in clinical practice is comprehensively systematized and discussed in this review. The dose-dependent adsorption and release kinetics mechanism of vitamin C is complex; however, this review may provide a holistic perspective on its potential as a preventive supplement and/or for combined precise and targeted therapeutics in cardiovascular management therapy.

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

Hemorrhagic shock and tissue injury provoke distinct components of trauma-induced coagulopathy in a swine model

INTRODUCTION

Tissue injury (TI) and hemorrhagic shock (HS) are the major contributors to trauma-induced coagulopathy (TIC). However, the individual contributions of these insults are difficult to discern clinically because they typically coexist. TI has been reported to release procoagulants, while HS has been associated with bleeding. We developed a large animal model to isolate TI and HS and characterize their individual mechanistic pathways. We hypothesized that while TI and HS are both drivers of TIC, they provoke different pathways; specifically, TI reduces time to clotting, whereas, HS decreases clot strength stimulates hyperfibrinolysis.

METHODS

After induction of general anesthesia, 50 kg male, Yorkshire swine underwent isolated TI (bilateral muscle cutdown of quadriceps, bilateral femur fractures) or isolated HS (controlled bleeding to a base excess target of - 5 mmol/l) and observed for 240 min. Thrombelastography (TEG), calcium levels, thrombin activatable fibrinolysis inhibitor (TAFI), protein C, plasminogen activator inhibitor 1 (PAI-1), and plasminogen activator inhibitor 1/tissue-type plasminogen activator complex (PAI-1-tPA) were analyzed at pre-selected timepoints. Linear mixed models for repeated measures were used to compare results throughout the model.

RESULTS

TI resulted in elevated histone release which peaked at 120 min (p = 0.02), and this was associated with reduced time to clot formation (R time) by 240 min (p = 0.006). HS decreased clot strength at time 30 min (p = 0.003), with a significant decline in calcium (p = 0.001). At study completion, HS animals had elevated PAI-1 (p = 0.01) and PAI-1-tPA (p = 0.04), showing a trend toward hyperfibrinolysis, while TI animals had suppressed fibrinolysis. Protein C, TAFI and skeletal myosin were not different among the groups.

CONCLUSION

Isolated injury in animal models can help elucidate the mechanistic pathways leading to TIC. Our results suggest that isolated TI leads to early histone release and a hypercoagulable state, with suppressed fibrinolysis. In contrast, HS promotes poor clot strength and hyperfibrinolysis resulting in hypocoagulability.

The Effects of Increasing Aortic Occlusion Times at the Level of the Highest Renal Artery (Zone II) in the Normovolemic Rabbit Model

PURPOSE

The purpose of this study was to evaluate the effects of increasing zone II resuscitative endovascular balloon occlusion of the aorta (REBOA) occlusion times on physiological, end-organ and inflammatory responses in rabbits to assess the safe aortic occlusion time in a normovolemic rabbit model.

METHODS

The zone ll aorta was occluded with a balloon in 32 rabbits (8 animals each for 15, 30, 60, and 90 min). 8 rabbits served as a control. ELISAs were used to examine the serum levels of ALT, AST, Cr, BUN, MDA, SOD, IL-8, IL-6, and TNF-α; HE staining was used to identify the morphological changes in the kidney; RT-PCR was used to detect the mRNA levels of IL-6, IL-8, TNF-α and NF-κB in the kidney and uterus; and Western blotting was used to measure the protein expression levels of IL-6, IL-8, TNF-α and NF-κB in the kidney and uterus.

RESULTS

Plasma concentrations of liver markers, kidney markers, inflammatory factors and oxidative stress indicators were significantly increased at the end of reperfusion in the 30 min, 60 min and 90 min groups. Damage to the kidney occurred in the 30 min, 60 min and 90 min groups. The mRNA and protein expression levels of IL-6, IL-8, TNF-α and NF-κB in the kidney and uterus were significantly increased at the end of reperfusion in the 30 min group, and as the time of occlusion extended, these levels continued to increase.

CONCLUSION

Activation of systemic inflammation and ischaemia-reperfusion injury of end-organs occurred when the occlusion time reached 30 min. Therefore, 15 min should be regarded as a safe period of REBOA in zone II.

Blast polytrauma with hemodynamic shock, hypothermia, hypoventilation and systemic inflammatory response: description of a new porcine model

PURPOSE

In the past decade blast injuries have become more prevalent. Blast trauma may cause extensive injuries requiring improved early resuscitation and prevention of haemorrhage. Randomized prospective trials are logistically and ethically challenging, and large animal models are important for further research efforts. Few severe blast trauma models have been described, which is why we aimed to establish a comprehensive polytrauma model in accordance with the criteria of the Berlin definition of polytrauma and with a survival time of > 2 h. Multiple blast injuries to the groin and abdomen were combined with hypoperfusion, respiratory and metabolic acidosis, hypoventilation, hypothermia and inflammatory response. The model was compared to lung contusion and haemorrhage.

METHODS

16 landrace swine (mean weight 60.5 kg) were randomized to "control" (n = 5), "chest trauma/hem" by lung contusion and class II haemorrhage (n = 5), and "blast polytrauma" caused by multiple blast injuries to the groin and abdomen, class II haemorrhage, lipopolysaccharide (LPS) infusion and hypothermia 32 °C (n = 6).

RESULTS

The blast polytrauma group had an Injury Severity Score of 57 which resulted in haemodynamic shock, hypothermia, respiratory and metabolic acidosis and inflammatory response. The chest trauma/hem group had an Injury Severity Score of 9 and less profound physiologic effects. Physiologic parameters presented a dose-response relationship corresponding to the trauma levels.

CONCLUSION

A comprehensive blast polytrauma model fulfilling the Berlin polytrauma criteria, with a high trauma load and a survival time of > 2 h was established. A severe, but consistent, injury profile was accomplished enabling the addition of experimental interventions in future studies, particularly of immediate resuscitation efforts including whole blood administration, trauma packing and haemostasis.

Role of AScorbic acid Infusion in critically ill patients with Transfusion Related Acute Lung Injury (ASTRALI)

INTRODUCTION

In critically ill patients, Transfusion Related Acute Lung Injury (TRALI) remains the leading cause of transfusion-related fatalities in critical care setting and associated with inflammation and oxidative stress state. Recent research raised the potential efficacy of high dose intravenous ascorbic acid in critically ill patients.

OBJECTIVE

The aim of this trial was to investigate the effect of high dose intravenous ascorbic acid (VC) as a targeted therapy for TRALI in terms of serum proinflammatory (interleukin-8, interleukin-1β, C-reactive protein), anti-inflammatory (interleukin-10), oxidative stress (superoxide dismutase, malondialdehyde) markers, and plasma VC levels. Secondary outcomes were oxygenation (PaO₂ /FiO₂ ratio), vasopressor use, duration of mechanical ventilation, ICU length of stay, 7-days mortality and 28-days mortality.

METHODS

Eighty critically ill patients with TRALI (n=80) were randomized to receive 2.5gm/6hr intravenous vitamin C for 96 hours (ASTRALI group) or placebo. Patients were followed-up to measure the outcomes initially (T0) and at the end of treatment (T96).

RESULTS

When compared to control group, ASTRALI group at T96, showed significantly higher median of interleukin-10 (31.6 ± 25.8 Vs. 17.7 ± 12.0 pg/mL, p<0.0001) levels and superoxide dismutase (12876 ± 4627 U/L Vs. 5895 ± 6632 U/L, p<0.0001) activities, lower median C-reactive protein (76 ± 50 Vs. 89 ± 56 mg/L, p=0.033), interleukin-8 (11.8 ± 7.3, 35.5 ± 19.8 pg/mL, p<0.0001), and malondialdehyde (0.197 ± 0.034 Vs. 0.234 ± 0.074 μM/L, p=0.002) levels.

CONCLUSION

High dose ascorbic acid was associated with significantly reduced oxidative stress, reduced pro-inflammatory markers except IL-1β, elevated anti-inflammatory marker, and elevated plasma VC levels.

Vitamin C Differentially Impacts the Serum Proteome Profile in Female and Male Mice

A suboptimal blood vitamin C (ascorbate) level increases the risk of several chronic diseases. However, the detection of hypovitaminosis C is not a simple task, as ascorbate is unstable in blood samples. In this study, we examined the serum proteome of mice lacking the gulonolactone oxidase (Gulo) required for the ascorbate biosynthesis. Gulo^-/- mice were supplemented with different concentrations of ascorbate in drinking water, and serum was collected to identify proteins correlating with serum ascorbate levels using an unbiased label-free liquid chromatography-tandem mass spectrometry global quantitative proteomic approach. Parallel reaction monitoring was performed to validate the correlations. We uncovered that the serum proteome profiles differ significantly between male and female mice. Also, unlike Gulo^-/- males, a four-week ascorbate treatment did not entirely re-establish the serum proteome profile of ascorbate-deficient Gulo^-/- females to the optimal profile exhibited by Gulo^-/- females that never experienced an ascorbate deficiency. Finally, the serum proteins involved in retinoid metabolism, cholesterol, and lipid transport were similarly affected by ascorbate levels in males and females. In contrast, the proteins regulating serum peptidases and the protein of the acute phase response were different between males and females. These proteins are potential biomarkers correlating with blood ascorbate levels and require further study in standard clinical settings. The complete proteomics data set generated in this study has been deposited to the public repository ProteomeXchange with the data set identifier: PXD027019.

Large animal models for translational research in acute kidney injury

While extensive research using animal models has improved the understanding of acute kidney injury (AKI), this knowledge has not been translated into effective treatments. Many promising interventions for AKI identified in mice and rats have not been validated in subsequent clinical trials. As a result, the mortality rate of AKI patients remains high. Inflammation plays a fundamental role in the pathogenesis of AKI, and one reason for the failure to translate promising therapeutics may lie in the profound difference between the immune systems of rodents and humans. The immune systems of large animals such as swine, nonhuman primates, sheep, dogs and cats, more closely resemble the human immune system. Therefore, in the absence of a basic understanding of the pathophysiology of human AKI, large animals are attractive models to test novel interventions. However, there is a lack of reviews on large animal models for AKI in the literature. In this review, we will first highlight differences in innate and adaptive immunities among rodents, large animals, and humans in relation to AKI. After illustrating the potential merits of large animals in testing therapies for AKI, we will summarize the current state of the evidence in terms of what therapeutics have been tested in large animal models. The aim of this review is not to suggest that murine models are not valid to study AKI. Instead, our objective is to demonstrate that large animal models can serve as valuable and complementary tools in translating potential therapeutics into clinical practice.

Reporting animal research: Explanation and elaboration for the ARRIVE guidelines 2.0

Improving the reproducibility of biomedical research is a major challenge. Transparent and accurate reporting is vital to this process; it allows readers to assess the reliability of the findings and repeat or build upon the work of other researchers. The ARRIVE guidelines (Animal Research: Reporting In Vivo Experiments) were developed in 2010 to help authors and journals identify the minimum information necessary to report in publications describing in vivo experiments. Despite widespread endorsement by the scientific community, the impact of ARRIVE on the transparency of reporting in animal research publications has been limited. We have revised the ARRIVE guidelines to update them and facilitate their use in practice. The revised guidelines are published alongside this paper. This explanation and elaboration document was developed as part of the revision. It provides further information about each of the 21 items in ARRIVE 2.0, including the rationale and supporting evidence for their inclusion in the guidelines, elaboration of details to report, and examples of good reporting from the published literature. This document also covers advice and best practice in the design and conduct of animal studies to support researchers in improving standards from the start of the experimental design process through to publication.

Vitamin C in Health and Disease: A Companion Animal Focus

Vitamin C is synthesized in the liver in most species, including dogs and cats, and is widely distributed through body tissues. Vitamin C has an important physiologic role in numerous metabolic functions including tissue growth and maintenance, amelioration of oxidative stress, and immune regulation. It is also a co-factor in the production of important substances such as catecholamines and vasopressin. Decreased vitamin C levels have been documented in a wide variety of diseases, and in critically ill human patients may be associated with increased severity of disease and decreased survival. Intravenous supplementation with vitamin C has been proposed as a potential life-saving treatment in conditions such as septic shock, and results of small some human trials are promising. Data in companion in animals is very limited, but the possible benefits and , seemingly low risk of adverse effects , and the low cost of this treatment make vitamin C therapy a promising area of future investigation in critically ill dogs and cats.

High-Dose Intravenous Ascorbic Acid: Ready for Prime Time in Traumatic Brain Injury?

Traumatic brain injury (TBI) is one of the leading public health problems in the USA and worldwide. It is the number one cause of death and disability in children and adults between ages 1-44. Despite efforts to prevent TBIs, the incidence continues to rise. Secondary brain injury occurs in the first hours and days after the initial impact and is the most effective target for intervention. Inflammatory processes and oxidative stress play an important role in the pathomechanism of TBI and are exacerbated by impaired endogenous defense mechanisms, including depletion of antioxidants. As a reducing agent, free radical scavenger, and co-factor in numerous biosynthetic reactions, ascorbic acid (AA, vitamin C) is an essential nutrient that rapidly becomes depleted in states of critical illness. The administration of high-dose intravenous (IV) AA has demonstrated benefits in numerous preclinical models in the areas of trauma, critical care, wound healing, and hematology. A safe and inexpensive treatment, high-dose IV AA administration gained recent attention in studies demonstrating an associated mortality reduction in septic shock patients. High-quality data on the effects of high-dose IV AA on TBI are lacking. Historic data in a small number of patients demonstrate acute and profound AA deficiency in patients with central nervous system pathology, particularly TBI, and a strong correlation between low AA concentrations and poor outcomes. While replenishing deficient AA stores in TBI patients should improve the brain's ability to tolerate oxidative stress, high-dose IV AA may prove an effective strategy to prevent or mitigate secondary brain injury due to its ability to impede lipid peroxidation, scavenge reactive oxygen species, suppress inflammatory mediators, stabilize the endothelium, and reduce brain edema. The existing preclinical data and limited clinical data suggest that high-dose IV AA may be effective in lowering oxidative stress and decreasing cerebral edema. Whether this translates into improved clinical outcomes will depend on identifying the ideal target patient population and possible treatment combinations, factors that need to be evaluated in future clinical studies. With its excellent safety profile and low cost, high-dose IV AA is ready to be evaluated in the early treatment of TBI patients to mitigate secondary brain injury and improve outcomes.

Current Knowledge about the Effect of Nutritional Status, Supplemented Nutrition Diet, and Gut Microbiota on Hepatic Ischemia-Reperfusion and Regeneration in Liver Surgery

Ischemia-reperfusion (I/R) injury is an unresolved problem in liver resection and transplantation. The preexisting nutritional status related to the gut microbial profile might contribute to primary non-function after surgery. Clinical studies evaluating artificial nutrition in liver resection are limited. The optimal nutritional regimen to support regeneration has not yet been exactly defined. However, overnutrition and specific diet factors are crucial for the nonalcoholic or nonalcoholic steatohepatitis liver diseases. Gut-derived microbial products and the activation of innate immunity system and inflammatory response, leading to exacerbation of I/R injury or impaired regeneration after resection. This review summarizes the role of starvation, supplemented nutrition diet, nutritional status, and alterations in microbiota on hepatic I/R and regeneration. We discuss the most updated effects of nutritional interventions, their ability to alter microbiota, some of the controversies, and the suitability of these interventions as potential therapeutic strategies in hepatic resection and transplantation, overall highlighting the relevance of considering the extended criteria liver grafts in the translational liver surgery.

Temporal map of the pig polytrauma plasma proteome with fluid resuscitation and intravenous vitamin C treatment

BACKGROUND

Fluid resuscitation plays a prominent role in stabilizing trauma patients with hemorrhagic shock yet there remains uncertainty with regard to optimal administration time, volume, and fluid composition (e.g., whole blood, component, colloids) leading to complications such as trauma-induced coagulopathies (TIC), acidosis, and poor oxygen transport. Synthetic fluids in combination with antioxidants (e.g., vitamin C) may resolve some of these problems.

OBJECTIVES

We applied quantitative mass spectrometry-based proteomics [liquid chromatography-mass spectrometry (LC-MS/MS)] to map the effects of fluid resuscitation and intravenous vitamin C (VitC) in a pig model of polytrauma (hemorrhagic shock, tissue injury, liver reperfusion, hypothermia, and comminuted bone fracture). The goal was to determine the effects of VitC on plasma protein expression, with respect to changes associated with coagulation and trauma-induced coagulopathy (TIC).

METHODS

Longitudinal blood samples were drawn from nine male Sinclair pigs at baseline, 2 h post trauma, and 0.25, 2, and 4 h post fluid resuscitation with 500 mL hydroxyethyl starch. Pigs were treated intravenously (N = 3/treatment group) with saline, 50 mg VitC/kg (Lo-VitC), or 200 mg VitC/kg (Hi-VitC) during fluid resuscitation.

RESULTS

A total of 436 plasma proteins were quantified of which 136 changed following trauma and resuscitation; 34 were associated with coagulation, complement cascade, and glycolysis. Unexpectedly, Lo-VitC and Hi-VitC treatments stabilized ADAMTS13 levels by ~4-fold (P = .056) relative to saline and enhanced ADAMTS13/von Willebrand factor (VWF) cleavage efficiency based on LC-MS/MS evidence for the semitryptic VWF cleavage product (VWF1275-1286 ).

CONCLUSIONS

This study provides the first comprehensive map of trauma-induced changes to the plasma proteome, especially with respect to proteins driving the development of TIC.

Reduced plasma ascorbic acid levels in recipients of myeloablative conditioning and hematopoietic cell transplantation

Hematopoietic cell transplantation (HCT) conditioned using myeloablative conditioning (MAC) is complicated by end organ injury due to endothelial dysfunction and graft versus host disease. Mucositis and oxidant injury results in micronutrient deficiency. Ascorbic acid (AA) levels were measured in 15 patients undergoing HCT conditioned with MAC (11 allogeneic and four autologous HCT). Ascorbate levels declined postconditioning to 27.3 μMol/L (±14.1) by day 0 (P = .03 compared with pretransplant baseline), reaching a nadir level of 21.5 (±13.8) on day 14 (P = .003) post-transplant. Patients undergoing allogeneic HCT continued to have low AA levels to day 60 post-transplant. The role of AA in maintaining endothelial function and hematopoietic as well as T-cell recovery is provided, developing the rationale for repletion of vitamin C following HCT.

Traumatic injury pattern is of equal relevance as injury severity for experimental (poly)trauma modeling

This study aims to elaborate the relevance of trauma severity and traumatic injury pattern in different multiple and/or polytrauma models by comparing five singular trauma to two different polytrauma (PT) models with high and one multiple trauma (MT) model with low injury-severity score (ISS). The aim is to provide a baseline for reducing animal harm according to 3Rs by providing less injury as possible in polytrauma modeling. Mice were randomly assigned to 10 groups: controls (Ctrl; n = 15), Sham (n = 15); monotrauma groups: hemorrhagic shock (HS; n = 15), thoracic trauma (TxT; n = 18), osteotomy with external fixation (Fx; n = 16), bilateral soft tissue trauma (bSTT; n = 16) or laparotomy (Lap; n = 16); two PT groups: PT I (TxT + HS + Fx; ISS = 18; n = 18), PT II (TxT + HS + Fx + Lap; ISS = 22; n = 18), and a MT group (TxT + HS + bSTT + Lap, ISS = 13; n = 18). Activity and mortality were assessed. Blood gas analyses and organ damage markers were determined after 6 h. Significant mortality occurred in TxT, PT and MT (11.7%). Activity decreased significantly in TxT, HS, both polytrauma and MT vs. Ctrl/Sham. PT-groups and MT had significantly decreased activity vs. bsTT, Lap or Fx. MT had significantly lower pCO₂vs. Ctrl/Sham, Lap or bsTT. Transaminases increased significantly in PT-groups and MT vs. Ctrl, Sham or monotrauma. Traumatic injury pattern is of comparable relevance as injury severity for experimental multiple or (poly)trauma modeling.

Role of vitamin C in diabetic ketoacidosis: Is it ready for prime time?

Diabetic ketoacidosis (DKA) is life-threatening acute metabolic complication of diabetes mellitus (DM) that is characterized by acidosis, ketosis, and hyperglycemia, currently affecting mostly patients under 30 years of age with diabetes mellitus type 1. In both, DM and DKA, a pro-inflammatory state exists. This clinical entity occurs as a result of hyperglycemia-induced disturbances, resulting in an increased oxidative metabolism. For the latter reason, the use of vitamin C seems promising in DKA due to its antioxidant role in reducing the superoxide radicals that are consequence of the oxidative stress. This can decrease the pro-inflammatory state and avoids complications. Vitamin C, or also known as ascorbic acid, has been widely used in several illnesses, such as common cold, tissue healing, fertility, atherosclerosis, cancer prevention, immunity restoration, neuro-degenerative disease and also has been suggested to decrease the risk of DM, and this reason is giving place to believe that vitamin C can have an important role in treating diabetic complications such as DKA. In order to counteract these oxidative disturbances in DKA patients, we analyzed the current data regarding vitamin C and evaluate its role in any type treatment of this complication in the near future.

Vitamin C in the critically ill - indications and controversies

Ascorbic acid (vitamin C) elicits pleiotropic effects in the body. Among its functions, it serves as a potent anti-oxidant, a co-factor in collagen and catecholamine synthesis, and a modulator of immune cell biology. Furthermore, an increasing body of evidence suggests that high-dose vitamin C administration improves hemodynamics, end-organ function, and may improve survival in critically ill patients. This article reviews studies that evaluate vitamin C in pre-clinical models and clinical trials with respect to its therapeutic potential.

Informing efficient pilot development of animal trauma models through quality improvement strategies

Poor quality data in preclinical trials can result from inconsistent and unstandardized experimental processes. Unpredictable pre-intervention variability generates unreliable data, biases outcomes and results in needless waste of animals and resources. We applied Define-Measure-Analyse-Improve-Control (DMAIC) quality improvement processes to pilot development of a swine model of trauma, haemorrhagic shock and coagulopathy. The goal was to reduce variability through protocol standardization and error reduction. Six male Sinclair swine were sequentially anesthetized, intubated, mechanically ventilated and instrumented, then subjected to multiple-hit injury, followed by fluid resuscitation monitoring and coagulation testing. Experimental tasks were defined and mapped. Performance measures were task performance times, subject stabilization time and number of task execution errors. Process improvement was assessed by reduced times and errors, and subject stability at target physiological values. Previously-overlooked performance errors and deficiencies were identified. 'Mistake-proofing' actions included personnel retraining, revisions of standard operating procedures and use of checklists. The quality improvement pilot trial produced a stable model with reduced protocol deviations. Data quality can be improved and animal waste minimized, if experimental planning incorporates strategies to ensure protocol adherence and reduced operator performance variation and errors. Properly designed pilot trials can be essential components of refinement and reduction strategies in animal-based research.

Vitamin C: should we supplement?

PURPOSE OF REVIEW

Hypovitaminosis C and vitamin C deficiency are very common in critically ill patients due to increased needs and decreased intake. Because vitamin C has pleiotropic functions, deficiency can aggravate the severity of illness and hamper recovery.

RECENT FINDINGS

Vitamin C is a key circulating antioxidant with anti-inflammatory and immune-supporting effects, and a cofactor for important mono and dioxygenase enzymes. An increasing number of preclinical studies in trauma, ischemia/reperfusion, and sepsis models show that vitamin C administered at pharmacological doses attenuates oxidative stress and inflammation, and restores endothelial and organ function. Older studies showed less organ dysfunction when vitamin C was administered in repletion dose (2-3 g intravenous vitamin C/day). Recent small controlled studies using pharmacological doses (6-16 g/day) suggest that vitamin C reduces vasopressor support and organ dysfunction, and may even decrease mortality.

SUMMARY

A short course of intravenous vitamin C in pharmacological dose seems a promising, well tolerated, and cheap adjuvant therapy to modulate the overwhelming oxidative stress in severe sepsis, trauma, and reperfusion after ischemia. Large randomized controlled trials are necessary to provide more evidence before wide-scale implementation can be recommended.