Changes in intestinal microbiota composition and metabolism coincide with increased intestinal permeability in young adults under prolonged physiological stress.

The magnitude, temporal dynamics, and physiological effects of intestinal microbiome responses to physiological stress are poorly characterized. This study used a systems biology approach and a multiple-stressor military training environment to determine the effects of physiological stress on intestinal microbiota composition and metabolic activity, as well as intestinal permeability (IP). Soldiers (n = 73) were provided three rations per day with or without protein- or carbohydrate-based supplements during a 4-day cross-country ski-march (STRESS). IP was measured before and during STRESS. Blood and stool samples were collected before and after STRESS to measure inflammation, stool microbiota, and stool and plasma global metabolite profiles. IP increased 62 ± 57% (mean ± SD, P < 0.001) during STRESS independent of diet group and was associated with increased inflammation. Intestinal microbiota responses were characterized by increased α-diversity and changes in the relative abundance of >50% of identified genera, including increased abundance of less dominant taxa at the expense of more dominant taxa such as Bacteroides Changes in intestinal microbiota composition were linked to 23% of metabolites that were significantly altered in stool after STRESS. Together, pre-STRESS Actinobacteria relative abundance and changes in serum IL-6 and stool cysteine concentrations accounted for 84% of the variability in the change in IP. Findings demonstrate that a multiple-stressor military training environment induced increases in IP that were associated with alterations in markers of inflammation and with intestinal microbiota composition and metabolism. Associations between IP, the pre-STRESS microbiota, and microbiota metabolites suggest that targeting the intestinal microbiota could provide novel strategies for preserving IP during physiological stress.NEW & NOTEWORTHY Military training, a unique model for studying temporal dynamics of intestinal barrier and intestinal microbiota responses to stress, resulted in increased intestinal permeability concomitant with changes in intestinal microbiota composition and metabolism. Prestress intestinal microbiota composition and changes in fecal concentrations of metabolites linked to the microbiota were associated with increased intestinal permeability. Findings suggest that targeting the intestinal microbiota could provide novel strategies for mitigating increases in intestinal permeability during stress.

Effects of a 7-day military training exercise on inflammatory biomarkers, serum hepcidin, and iron status.

BACKGROUND: Hepcidin, a peptide that is released into the blood in response to inflammation, prevents cellular iron export and results in declines in iron status. Elevated serum and urinary levels of hepcidin have been observed in athletes following exercise, and declines in iron status have been reported following prolonged periods of training. The objective of this observational study was to characterize the effects of an occupational task, military training, on iron status, inflammation, and serum hepcidin. FINDINGS: Volunteers (n = 21 males) included Norwegian Soldiers participating in a 7-day winter training exercise that culminated in a 3-day, 54 km ski march. Fasted blood samples were collected at baseline, on day 4 (PRE, prior to the ski march), and again on day 7 (POST, following the ski march). Samples were analyzed for hemoglobin, serum ferritin, soluble transferrin receptor (sTfR), interleukin-6 (IL-6), and serum hepcidin. Military training affected inflammation and serum hepcidin levels, as IL-6 and hepcidin concentrations increased (P < 0.05) from the baseline to POST (mean ± SD, 9.1 ± 4.9 vs. 14.5 ± 8.4 pg/mL and 6.5 ± 3.5 vs. 10.2 ± 6.9 ng/mL, respectively). Iron status was not affected by the training exercise, as sTfR levels did not change over the course of the 7-day study. CONCLUSIONS: Military training resulted in significant elevations in IL-6 and serum hepcidin. Future studies should strive to identify the role of hepcidin in the adaptive response to exercise, as well as countermeasures for the prevention of chronic or repeated elevations in serum hepcidin due to exercise or sustained occupational tasks which may result in longer term decrements in iron status.

One week of multifactorial high-stress military ranger training affects Gram-negative signalling.

BACKGROUND: Toll-like receptor 4 (TLR4), especially expressed on monocytes/macrophages, connects microbial and sterile innate immune activation. Lipopolysaccharide (LPS) from Gram-negative bacteria and several endogenous molecules, among others saturated fatty acids (SFAs), are able to induce signalling through this receptor. Downstream inflammatory cytokines orchestrate the immune response. Our aim was to investigate how long-lasting multifactorial stress affects Gram-negative signalling and search for possible correlations between cytokine production and TLR4 expression or SFA concentration. METHODS: Eight healthy males were studied during a 7-day ranger-training course with semi-continuous physical strain, together with energy and sleep restrictions. Blood drawn on days 0, 3, 5 and 7 was incubated ex vivo for 6 h with or without LPS 10 ng/mL, whereupon surface expression of TLR4 on CD14⁺ monocytes and supernatant concentrations of inflammatory cytokines (TNF-α, IL-1ß and IL-6) were measured. In addition, plasma free fatty acids were quantified. RESULTS: Monocyte TLR4 expression was elevated throughout the course (p < 0.05 vs. baseline). Corresponding results were found for SFAs. The concentration of TNF-α increased significantly on day 3 and thereafter normalized, and a similar pattern was seen for IL-1ß. No correlations were found between cytokine concentrations and monocyte TLR4 expression or plasma SFAs. CONCLUSION: Multifactorial stress significantly affected ex vivo production of TNF-α and monocyte surface expression of TLR4. In addition, mobilization of fat resulted in increased plasma concentrations of SFAs. No associations between inflammatory cytokines and monocyte TLR4 expression or SFAs were found.

Moderate temperature alterations affect Gram-negative immune signalling in ex vivo whole blood.

BACKGROUND: Alterations in body temperature may influence immune system function and consequently affect the risk of infection and inflammatory diseases. Lipopolysaccharide (LPS) from gram-negative bacteria induces production of inflammatory cytokines after ligand binding to Toll-like receptor 4 (TLR4) on immune cells (especially monocytes/ macrophages). Our aim was to explore how clinically relevant hypo- and hyperthermia affect this signalling in an ex vivo whole blood model, and investigate if the cytokine response was correlated with monocyte TLR4 expression level. METHODS: Blood from 11 healthy volunteers was incubated with LPS 10 ng/ml for 6 h at 33, 37 or 40°C. The concentrations of selected pro-inflammatory (tumour necrosis factor-α (TNF-α) and interleukin (IL)-1ß) and anti-inflammatory (IL-10) cytokines were measured in plasma, and the surface expression of TLR4 was quantified on CD14 + monocytes. RESULTS: Monocyte TLR4 expression and plasma IL-1ß were inversely related to temperature. The TNF-α production was unaffected by hypothermia but increased significantly during hyperthermia, whereas plasma IL-10 was significantly reduced during both hypo- and hyperthermic incubation. No correlation was found between TLR4 expression and cytokine concentrations. During hypothermia, the TNF-α/IL-10 and IL-1ß/IL-10 ratios increased seven and nine times, respectively. Hyperthermia increased the TNF-α/IL-10 ratio, but to a lesser extent (doubling), whereas the IL-1ß/IL-10 ratio remained unchanged. CONCLUSION: Hypothermia significantly changed the cytokine ratios in the pro-inflammatory direction. In comparison, the effect of hyperthermia was sparse, with a modest increase in the TNF-α/IL-10 ratio only. No association was found between LPS-stimulated cytokine production and TLR4 expression on CD14 + monocytes.

Activation of cytokine synthesis by systemic infusions of lipopolysaccharide and peptidoglycan in a porcine model in vivo and in vitro.

BACKGROUND: The incidence of gram-positive and mixed bacterial infections in surgical patients has increased, and there has been an alarming rise in the number of drug-resistant bacteria. Peptidoglycan (PepG) is a cell wall component of gram-positive bacteria that stimulates inflammatory responses both ex vivo and in vivo. The systemic effects of PepG on inflammation have not been studied in a large animal model. METHODS: Anesthetized pigs were subjected to 8-h continuous intravenous infusions of lipopolysaccharide (LPS) (4 mcg/kg/h), PepG (40 mcg/kg/h), LPS plus PepG, or saline. The concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, IL-8, and IL-10 were measured in the plasma prior to infusion (time 0) and thereafter every second hour until the end of the experiments. Heparinized whole blood samples drawn at time 0 and after a 6-h infusion of LPS or PepG were incubated ex vivo with PepG (10 mcg/mL), LPS (10 ng/mL), or a combination of PepG and LPS to study the immunologic consequences of systemic inflammation. Concentrations of TNF-alpha, IL-8, and IL-1beta were measured in the supernatant liquids. RESULTS: In vivo, there was transient upregulation of TNF-alpha after infusion of LPS, PepG, or the combination. Interleukin-6 and IL-8 were upregulated by LPS but not by PepG. In vitro studies of whole blood obtained at time 0 revealed a synergistic effect of LPS and PepG on the release of TNF-alpha. Incubation of whole blood obtained after 6 h of infusion of LPS or PepG revealed tolerance and cross-tolerance between the two bacterial components in the induction of TNF-alpha, IL-8, and IL-1beta. CONCLUSIONS: Peptidoglycan is a potent inducer of TNF-alpha in this large animal model. Peptidoglycan and LPS synergized to increase the formation of the proinflammatory cytokine TNF-alpha. The study demonstrates for the first time the development of tolerance and cross-tolerance between LPS and PepG in a large animal model. These phenomena could be of importance for the signs and symptoms of sepsis.

Cardiovascular and thermal strain during 3-4 days of a metabolically demanding cold-weather military operation.

BACKGROUND: Cardiovascular (CV) and thermal responses to metabolically demanding multi-day military operations in extreme cold-weather environments are not well described. Characterization of these operations will provide greater insights into possible performance capabilities and cold injury risk. METHODS: Soldiers from two cold-weather field training exercises (FTX) were studied during 3-day (study 1, n = 18, age: 20 ± 1 year, height: 182 ± 7 cm, mass: 82 ± 9 kg) and 4-day (study 2, n = 10, age: 20 ± 1 year, height: 182 ± 6 cm, mass: 80.7 ± 8.3 kg) ski marches in the Arctic. Ambient temperature ranged from -18 to -4 °C during both studies. Total daily energy expenditure (TDEE, from doubly labeled water), heart rate (HR), deep body (Tpill), and torso (Ttorso) skin temperature (obtained in studies 1 and 2) as well as finger (Tfing), toe (Ttoe), wrist, and calf temperatures (study 2) were measured. RESULTS: TDEE was 6821 ± 578 kcal day-1 and 6394 ± 544 for study 1 and study 2, respectively. Mean HR ranged from 120 to 140 bpm and mean Tpill ranged between 37.5 and 38.0 °C during skiing in both studies. At rest, mean Tpill ranged from 36.0 to 36.5 °C, (lowest value recorded was 35.5 °C). Mean Tfing ranged from 32 to 35 °C during exercise and dropped to 15 °C during rest, with some Tfing values as low as 6-10 °C. Ttoe was above 30 °C during skiing but dropped to 15-20 °C during rest. CONCLUSIONS: Daily energy expenditures were among the highest observed for a military training exercise, with moderate exercise intensity levels (~65% age-predicted maximal HR) observed. The short-term cold-weather training did not elicit high CV and Tpill strain. Tfing and Ttoe were also well maintained while skiing, but decreased to values associated with thermal discomfort at rest.

Effects of Supplemental Energy on Protein Balance during 4-d Arctic Military Training.

UNLABELLED: Soldiers often experience negative energy balance during military operations that diminish whole-body protein retention, even when dietary protein is consumed within recommended levels (1.5-2.0 g·kg·d). PURPOSE: The objective of this study is to determine whether providing supplemental nutrition spares whole-body protein by attenuating the level of negative energy balance induced by military training and to assess whether protein balance is differentially influenced by the macronutrient source. METHODS: Soldiers participating in 4-d arctic military training (AMT) (51-km ski march) were randomized to receive three combat rations (CON) (n = 18), three combat rations plus four 250-kcal protein-based bars (PRO, 20 g protein) (n = 28), or three combat rations plus four 250-kcal carbohydrate-based bars daily (CHO, 48 g carbohydrate) (n = 27). Energy expenditure (D2O) and energy intake were measured daily. Nitrogen balance (NBAL) and protein turnover were determined at baseline (BL) and day 3 of AMT using 24-h urine and [N]-glycine. RESULTS: Protein and carbohydrate intakes were highest (P < 0.05) for PRO (mean ± SD, 2.0 ± 0.3 g·kg·d) and CHO (5.8 ± 1.3 g·kg·d), but only CHO increased (P < 0.05) energy intake above CON. Energy expenditure (6155 ± 515 kcal·d), energy balance (-3313 ± 776 kcal·d), net protein balance (NET) (-0.24 ± 0.60 g·d), and NBAL (-68.5 ± 94.6 mg·kg·d) during AMT were similar between groups. In the combined cohort, energy intake was associated (P < 0.05) with NET (r = 0.56) and NBAL (r = 0.69), and soldiers with the highest energy intake (3723 ± 359 kcal·d, 2.11 ± 0.45 g protein·kg·d, 6.654 ± 1.16 g carbohydrate·kg·d) achieved net protein balance and NBAL during AMT. CONCLUSION: These data reinforce the importance of consuming sufficient energy during periods of high energy expenditure to mitigate the consequences of negative energy balance and attenuate whole-body protein loss.

Effects of exercise mode, energy, and macronutrient interventions on inflammation during military training.

Load carriage (LC) exercise may exacerbate inflammation during training. Nutritional supplementation may mitigate this response by sparing endogenous carbohydrate stores, enhancing glycogen repletion, and attenuating negative energy balance. Two studies were conducted to assess inflammatory responses to acute LC and training, with or without nutritional supplementation. Study 1: 40 adults fed eucaloric diets performed 90-min of either LC (treadmill, mean ± SD 24 ± 3 kg LC) or cycle ergometry (CE) matched for intensity (2.2 ± 0.1 VO2peak L min(-1)) during which combined 10 g protein/46 g carbohydrate (223 kcal) or non-nutritive (22 kcal) control drinks were consumed. Study 2: 73 Soldiers received either combat rations alone or supplemented with 1000 kcal day(-1) from 20 g protein- or 48 g carbohydrate-based bars during a 4-day, 51 km ski march (~45 kg LC, energy expenditure 6155 ± 515 kcal day(-1) and intake 2866 ± 616 kcal day(-1)). IL-6, hepcidin, and ferritin were measured at baseline, 3-h post exercise (PE), 24-h PE, 48-h PE, and 72-h PE in study 1, and before (PRE) and after (POST) the 4-d ski march in study 2. Study 1: IL-6 was higher 3-h and 24-h post exercise (PE) for CE only (mode × time, P < 0.05), hepcidin increased 3-h PE and recovered by 48-h, and ferritin peaked 24-h and remained elevated 72-h PE (P < 0.05), regardless of mode and diet. Study 2: IL-6, hepcidin and ferritin were higher (P < 0.05) after training, regardless of group assignment. Energy expenditure (r = 0.40), intake (r = -0.26), and balance (r = -0.43) were associated (P < 0.05) with hepcidin after training. Inflammation after acute LC and CE was similar and not affected by supplemental nutrition during energy balance. The magnitude of hepcidin response was inversely related to energy balance suggesting that eating enough to balance energy expenditure might attenuate the inflammatory response to military training.

N-Acetylcysteine administered as part of the immediate post-traumatic resuscitation regimen does not significantly influence initiation of inflammatory responses or subsequent endotoxin hyporesponsiveness.

Polytrauma and resuscitative efforts induce extensive alterations in the host's internal environment and cellular responses that may be a serious threat to these patients. Administration of exogenous thiols has been recommended to modulate the post-traumatic inflammatory responses. In this study, we have investigated the effect of N-acetylcysteine (NAC) on the early markers of leukocyte activation and subsequent endotoxin hyporesponsiveness. Twenty-eight pigs were exposed to a standardized gunshot injury. First aid treatment and initial life saving surgery was started without delay. One group (n = 14) was randomised to receive NAC 200 mg kg(-1) over 20 min, the remaining group was given the same volume of vehicle. Blood samples drawn at time points 0 and 75 min were also studied in vitro and stimulated with LPS or LPS plus NAC. Selected physiologic variables and degree of organ injury were equal in both groups. TNF-alpha, IL-1beta, and reactive oxygen species (ROS) tended to be lower in the NAC-group (NS). In vitro, NAC significantly reduced the release of the same cytokines after the LPS challenge in blood drawn before injury. NAC did not influence post-traumatic endotoxin tolerance. Adding NAC to the immediate resuscitation fluid did not influence the early post-traumatic organ injury, and initiation of inflammatory responses significantly, or endotoxin tolerance. In vitro, NAC significantly reduced proinflammatory cytokine release, but only in normal blood. The clinical value of this treatment regimen is probably restricted, both due to the unfavourable post-traumatic internal environment and imposed dosing limitations.

[Brominated flame retardants may cause brain injuries in the fetus and the newborn]. / Bromerte flammehemmere kan gi hjerneskader hos fostre og nyfødte.

BACKGROUND: Brominated flame retardants are incorporated into an ever-increasing number of ordinary consumer goods, which has lead to pollution of the environment, wildlife, food of animal origin, and human blood, adipose tissue, and mother's milk. This group of chemicals has a striking structural similarity with the thyroid hormones and may constitute a potential health risk by interfering with thyroid hormone homeostasis. MATERIAL AND METHODS: We focus on these features and discuss possible clinical consequences, on the basis of Medline searches and our own experience. RESULTS: The thyroid hormones are essential for normal brain development. Disruption of the hormonal balance may lead to serious and permanent defects of neurological functioning. Brominated flame retardants may interfere with thyroid synthesis, transport, receptor binding, and elimination. The clinical consequences have so far not been firmly established, but results from animal studies suggest that even subtle disturbances of thyroid homeostasis during pregnancy may have serious implications for the developing brain. INTERPRETATION: Numerous scientific reports confirm the neurotoxic potential of these chemicals. The foetus and newborn are especially vulnerable.

Maternal Deprivation of Lewis Rat Pups Increases the Severity of Experi-mental Periodontitis in Adulthood.

BACKGROUND AND OBJECTIVE: Early life adverse events may influence susceptibility/resistance to chronic inflammatory diseases later in life by permanently dysregulating brain-controlled immune-regulatory systems. We have investigated the impact of infant-mother separation during early postnatal life on the severity of experimental periodontitis, as well as systemic stress and immune responses, in adulthood. MATERIAL AND METHODS: Pups of periodontitis resistant Lewis rats were separated from their mothers for 3 h daily during postnatal days 2-14 (termed maternal deprivation; MD), separated for 15 min daily during the same time period (termed handling; HD), or left undisturbed. As adults, their behaviour was tested in a novel stressful situation, and ligature-induced periodontitis applied for 21 days. Two h before sacrifice all rats were exposed to a gram-negative bacterial lipopolysaccharide (LPS) challenge to induce a robust immune and stress response. RESULTS: Compared to undisturbed controls, MD rats developed significantly more periodontal bone loss as adults, whereas HD rats showed a tendency to less disease. MD and HD rats exhibited depression-like behaviour in a novel open field test, while MD rats showed higher glucocorticoid receptor (Gr) expression in the hippocampus, and HD rats had altered methylation of genes involved in the expression of hippocampal Gr. LPS provoked a significantly lower increase in circulating levels of the cytokine TGF-1ß in MD and HD rats, but there were no significant differences in levels of the stress hormone corticosterone. CONCLUSION: Stressful environmental exposures in very early life may alter immune responses in a manner that influences susceptibility/resistance to periodontitis.

Regulation of CCN1 (Cyr61) in a porcine model of intestinal ischemia/reperfusion.

Intestinal ischemia is a serious condition that may lead to both local and systemic inflammatory responses. Restoration of blood supply (reperfusion) to ischemic tissues often increases the extent of the tissue injury. Cysteine-rich angiogenic inducer 61 (Cyr61)/CCN1 is an extracellular matrix-associated signaling protein that has diverse functions. CCN1 is highly expressed at sites of inflammation and wound repair, and may modify cell responses. This study aimed to investigate regulation and cellular distribution of CCN1 in intestinal ischemia/reperfusion (I/R) injury in pigs. After intestinal I/R, increased expression of CCN1 was detected by quantitative RT-PCR, Western blot analysis and immunohistochemistry compared with non-ischemic intestine. Immunoflorescence staining revealed that CCN1 was mainly up-regulated in intestinal mucosa after intestinal I/R. Microvillus epithelial cells and vascular endothelial cells were strongly positive for CCN1 in intestinal I/R, while natural killer cells and/or subsets of neutrophils were only modestly positive for CCN1. Furthermore, blood samples taken from the portal and caval veins during ischemia and after reperfusion showed no change of the CCN1 levels, indicating that CCN1 was locally regulated. In conclusion, these observations show, for the first time, that the CCN1 molecule is up-regulated in response to intestinal I/R in a local manner.

Rapid rewarming after mild hypothermia accentuates the inflammatory response after acute volume controlled haemorrhage in spontaneously breathing rats.

Accidental hypothermia is a common companion of trauma/haemorrhage, and several clinical studies have identified reduced body temperature as an independent risk predisposing to increased morbidity and mortality. Accordingly, the majority of trauma care guidelines prescribe early and aggressive rewarming of hypothermic patients. Enzyme reactions are generally downregulated at temperatures below 37 degrees C, including most of those responsible for the inflammatory response. The rationale for adhering to these recommendations uncritically may therefore be questioned. In a rat model of mild hypothermia and haemorrhagic shock we wanted to compare the influence of rapid rewarming with persistently reduced temperature on the synthesis of early inflammatory mediators and organ function. Thirty-four male albino Sprague-Dawley rats were studied. Withdrawal of 2.5 ml blood/100 g body weight was performed over 10 min, with simultaneous reduction of body temperature to 32.5-33.5 degrees C. Seventy-five minutes after initiation of bleeding, two-thirds of the shed blood was retransfused. One group (n=17) was rewarmed to normothermia, the other (n=17) was kept hypothermic. The study was terminated after an observation period of 2 h. At the end of the study the rewarmed animals had a significantly lower mean arterial pressure, higher heart rate, higher synthesis of reactive oxygen species from peritoneal phagocytes, increased circulating levels of nitric oxide, and higher values of the organ markers aspartate aminotransferase and urea. The pro-inflammatory cytokines TNF-alpha and IL-6, the anti-inflammatory cytokine IL-10, the organ markers alanine aminotransferase, alpha-glutathione S-transferase and creatinine, as well as organ injury scores were equal in both groups. Three rewarmed rats died prematurely, versus one hypothermic animal. In conclusion, the results suggest that during the early stages after haemorrhagic shock, rapid rewarming from mild hypothermia may have unfavourable effects both on basic haemodynamic variables, and on the internal inflammatory environment of cells and tissues.

[Glycine]. / Glysin.

BACKGROUND: Glycine is an essential component of important biological molecules, a key substance in many metabolic reactions, the major inhibitory neurotransmitter in the spinal cord and brain stem, and has anti-inflammatory, cytoprotective, and immunomodulatory qualities. MATERIAL AND METHODS: Based on available literature we discuss some important biological properties of glycine and give a short account of our own studies in this field. RESULTS: The main area of glycine research has traditionally been associated with its role as a neurotransmitter in the central nervous system. During the last few years there has been a mounting interest in effects on other organs and tissues as well. Glycine-gated chloride channels, originally demonstrated on neurons in the central nervous system, have been found on most leukocytes and a number of other cell types. This has provided a unifying mechanism of action that explains how glycine may influence such important and diverse biological processes as transmission of nerve signals and initiation of the immune response. INTERPRETATION: Glycine is a simple, easily available and inexpensive substance with few and innocuous side effects. Despite the recent unveiling of tantalizing aspects regarding its mechanism of action, biological activities and therapeutic potential, clinical use has remained scant.

Effects of winter military training on energy balance, whole-body protein balance, muscle damage, soreness, and physical performance.

Physiological consequences of winter military operations are not well described. This study examined Norwegian soldiers (n = 21 males) participating in a physically demanding winter training program to evaluate whether short-term military training alters energy and whole-body protein balance, muscle damage, soreness, and performance. Energy expenditure (D2(18)O) and intake were measured daily, and postabsorptive whole-body protein turnover ([(15)N]-glycine), muscle damage, soreness, and performance (vertical jump) were assessed at baseline, following a 4-day, military task training phase (MTT) and after a 3-day, 54-km ski march (SKI). Energy intake (kcal·day(-1)) increased (P < 0.01) from (mean ± SD (95% confidence interval)) 3098 ± 236 (2985, 3212) during MTT to 3461 ± 586 (3178, 3743) during SKI, while protein (g·kg(-1)·day(-1)) intake remained constant (MTT, 1.59 ± 0.33 (1.51, 1.66); and SKI, 1.71 ± 0.55 (1.58, 1.85)). Energy expenditure increased (P < 0.05) during SKI (6851 ± 562 (6580, 7122)) compared with MTT (5480 ± 389 (5293, 5668)) and exceeded energy intake. Protein flux, synthesis, and breakdown were all increased (P < 0.05) 24%, 18%, and 27%, respectively, during SKI compared with baseline and MTT. Whole-body protein balance was lower (P < 0.05) during SKI (-1.41 ± 1.11 (-1.98, -0.84) g·kg(-1)·10 h) than MTT and baseline. Muscle damage and soreness increased and performance decreased progressively (P < 0.05). The physiological consequences observed during short-term winter military training provide the basis for future studies to evaluate nutritional strategies that attenuate protein loss and sustain performance during severe energy deficits.

Effects of infliximab and hydrocortisone on in vitro cytokine responses after stimulation with lipopolysaccharide.

BACKGROUND: Both glucocorticosteroids and biologic drugs such as the tumor necrosis factor (TNF)-α antagonist infliximab are used often in the treatment of rheumatoid arthritis or inflammatory bowel disease. In severe disease, or if allergic reactions occur during treatment with infliximab, combined therapy with these drugs often is instituted. Combining infliximab and glucocorticosteroids may increase substantially the risk of severe opportunistic infections or dissemination of malignant tumors because of their additive effects as immunosuppressants. METHODS: In a whole-blood in vitro model, we studied the influence of different doses of infliximab and hydrocortisone, either separately or in combination, on the synthesis of selected cytokines after stimulation with lipopolysaccharide (LPS). RESULTS: Hydrocortisone in therapeutic serum concentrations significantly inhibited the expression of a majority of the cytokines tested. Infliximab, in serum concentrations relevant to clinical situations, inhibited TNF-α activity significantly. This effect was potentiated when infliximab was combined with hydrocortisone. Similar effects were found using a low dose of infliximab combined with hydrocortisone. Infliximab alone inhibited the expression of the cytokines interleukin (IL)-1 receptor antagonist, monocyte chemoattractant protein-1, IL-8, and IL-12. Hydrocortisone in combination with low-dose infliximab potentiated the suppressive effects on TNF-α, IL-1ß, IL-8, and macrophage inflammatory protein-1α synthesis. CONCLUSIONS: Immune-modulating effects of infliximab were found both in clinically relevant doses and, most notably, in low doses reflecting serum concentrations found commonly in patients several months after the last injection. Infliximab potentiates the suppressive effects of hydrocortisone on cytokine synthesis.

Changes in fibrinogen availability and utilization in an animal model of traumatic coagulopathy.

BACKGROUND: Impaired haemostasis following shock and tissue trauma is frequently detected in the trauma setting. These changes occur early, and are associated with increased mortality. The mechanism behind trauma-induced coagulopathy (TIC) is not clear. Several studies highlight the crucial role of fibrinogen in posttraumatic haemorrhage. This study explores the coagulation changes in a swine model of early TIC, with emphasis on fibrinogen levels and utilization of fibrinogen. METHODS: A total of 18 landrace pigs were anaesthetized and divided into four groups. The Trauma-Shock group (TS) were inflicted bilateral blast femoral fractures with concomitant soft tissue injury by a high-energy rifle shot to both hind legs, followed by controlled exsanguination. The Shock group (S) was exposed to shock by exsanguination, whereas a third group was exposed to trauma only (T). A fourth group (C) served as control. Physiological data, haematological measurements, blood gas analyses and conventional coagulation assays were recorded at baseline and repeatedly over 60 minutes. Thrombelastometry were performed by means of the tissue factor activated ExTEM assay and the platelet inhibiting FibTEM assay. Data were statistically analysed by repeated measurements analyses method. RESULTS: A significant reduction of fibrinogen concentration was observed in both the TS and S groups. INR increased significantly in the S group and differed significantly from the TS group. Maximum clot firmness (MCF) of the ExTEM assay was significantly reduced over time in both TS and S groups. In the FibTEM assay a significant shortening of the clotting time and an increase in MCF was observed in the TS group compared to the S group. CONCLUSION: Despite a reduction in clotting capability measured by ExTEM MCF and a reduced fibrinogen concentration, extensive tissue trauma may induce an increased fibrin based clotting activity that attenuates the hypocoagulable tendency in exsanguinated animals.

Systemic chemical desensitization of peptidergic sensory neurons with resiniferatoxin inhibits experimental periodontitis.

BACKGROUND AND OBJECTIVE: The immune system is an important player in the pathophysiology of periodontitis. The brain controls immune responses via neural and hormonal pathways, and brain-neuro-endocrine dysregulation may be a central determinant for pathogenesis. Our current knowledge also emphasizes the central role of sensory nerves. In line with this, we wanted to investigate how desensitization of peptidergic sensory neurons influences the progression of ligature-induced periodontitis, and, furthermore, how selected cytokine and stress hormone responses to Gram-negative bacterial lipopolysaccharide (LPS) stimulation are affected. MATERIAL AND METHODS: Resiniferatoxin (RTX; 50 µg/kg) or vehicle was injected subcutaneously on days 1, 2, and 3 in stress high responding and periodontitis-susceptible Fischer 344 rats. Periodontitis was induced 2 days thereafter. Progression of the disease was assessed after the ligatures had been in place for 20 days. Two h before decapitation all rats received LPS (150 µg/kg i.p.) to induce a robust immune and stress response. RESULTS: Desensitization with RTX significantly reduced bone loss as measured by digital X-rays. LPS provoked a significantly higher increase in serum levels of the pro-inflammatory cytokine tumour necrosis factor (TNF)-α, but lower serum levels of the anti-inflammatory cytokine interleukin (IL)-10 and the stress hormone corticosterone. CONCLUSIONS: In this model RTX-induced chemical desensitization of sensory peptidergic neurons attenuated ligature-induced periodontitis and promoted a shift towards stronger pro-inflammatory cytokine and weaker stress hormone responses to LPS. The results may partly be explained by the attenuated transmission of immuno-inflammatory signals to the brain. In turn, this may weaken the anti-inflammatory brain-derived pathways.

Impact of hypertonic saline on the release of selected cytokines after stimulation with LPS or peptidoglycan in ex vivo whole blood from healthy humans.

The question of specific immunomodulating qualities of hypertonic saline (HTS) has not been settled. It has proven difficult to distinguish between immunomodulation directly attributable to HTS and influence because of favorable circulatory effects. The nature of immune activator may also play a role. In a whole-blood model, we have investigated these relations further, with special emphasize on osmolalities usually found after recommended dosing. Blood from 10 healthy donors was exposed to osmolalities ranging from 295 to 480 mOsm/kg and stimulated with the two clinically relevant stimulators peptidoglycan (1 µg/mL) or LPS (10 ng/mL) for 6 h at 37°C. Leukocyte response was evaluated by measuring selected cytokines in the supernatant. Moderate hyperosmolality alone boosted the release of CXCL8/IL-8. The peptidoglycan-stimulated synthesis of pivotal proinflammatory cytokines was inhibited in an osmolality-dependent way, but statistically significant only at osmolalities above those attained after routine use of HTS, i.e., 310 mOsm/kg or greater: IL-6 (P < 0.05 at 315 mOsm/kg), IL-1ß, and TNF-α (P < 0.05 at 335 mOsm/kg). Similar effects were seen for the chemokine CCL3 and the anti-inflammatory cytokine IL-10. In contrast, the effects in cells stimulated with LPS were either lower or absent. Thus, osmolalities usually found after clinical use of HTS only modestly influenced the selected immune parameters, regardless of stimulator.

Nitric oxide administration restores the hepatic artery buffer response during porcine endotoxemia.

The hepatic artery buffer response, which is lost during endotoxemia, plays a central role in the autoregulation of liver perfusion. A temporarily decreased synthesis of nitric oxide during early endotoxemia might be responsible for this dysfunction; hence exogenous administration of nitric oxide could reestablish the autoregulation of hepatic blood flow and help prevent hepatic damage later in septic shock. Fifteen pigs were treated with lipopolysaccharide +/- the nitric oxide donor nitroprusside-sodium via the portal vein. Hemodynamics were measured, and serum chemistry and liver biopsies for nitric oxide synthase expression were obtained. Lipopolysaccharide decreased arterial liver perfusion after 5 hours by 38% (p = .012), which was reversed by addition of nitroprusside (8%). Administration of nitroprusside preserved an increase of 28% in hepatic arterial upon portal vein flow reduction (p < .001). Nitroprusside maintained mRNA levels of constitutive nitric oxide synthase in liver tissue which were decreased by lipopolysaccharide (p = .026 vs. p = .114) and tempered the burst in inducible nitric oxide synthase expression at t = 3 hours. The early administration of the nitric oxide donor sodium nitroprusside during endotoxemia is able to reestablish the autoregulatory response of the hepatic artery following reduction of hepatic blood flow. This beneficial effect might help to prevent subsequent hepatic damage in the course of abdominal sepsis.