Sasha D. Adams

Acute, regional inflammatory response after traumatic brain injury: Implications for cellular therapy

BACKGROUND Although cellular therapy has shown promise in the management of traumatic brain injury (TBI), microenvironment interactions between the intracerebral milieu and therapeutic stem cells are poorly understood. We sought to characterize the acute, regional inflammatory response after TBI. METHODS Rats underwent a controlled cortical impact (CCI) injury or sham injury, were killed at 6, 12, 24, 48, and 72 hours, and intracerebral fluid (IF) was isolated from the direct injury, penumbral, ipsilateral frontal, and contralateral regions. Cortical and hippocampal areas were also isolated. Regional cytokine levels were measured. Polymorphonuclear cell (PMN) oxidative burst and marker expression were assessed after incubation with the IF. Immunohistochemistry was used to identify intracerebral CD68(+) cells (microglia/macrophages). RESULTS The proinflammatory cytokines interleukin (IL)-1alpha, IL-1beta, IL-6, and tumor necrosis factor-alpha were significantly elevated after CCI in the injury and penumbral regions. Increases in the same cytokines were localized to the cortex and the hippocampus. Increased PMN expression of CD11b and L-selectin was identified after incubation with injury or penumbral area IF, without change in PMN oxidative burst. CD68(+) cells were noted in the direct injury and penumbral areas. CONCLUSION The local cerebral milieu in the first 48 hours after TBI is highly proinflammatory. This response is most pronounced in areas at or proximal to the direct injury. The local, acute proinflammatory response after TBI may serve as a therapeutic target of early cell therapy or, conversely, may create an unfavorable local milieu, limiting the efficacy of early cellular therapy.

Fulminant Clostridium difficile colitis.

Purpose of reviewClostridium difficile is the most common cause of nosocomial infectious diarrhea in adults. The purpose of this review is to increase awareness that infection from C. difficile is not always indolent, but with fulminant colitis, it can be lethal. The epidemiology, pathogenesis and treatment of C. difficile infection are discussed, with special emphasis on management of fulminant colitis. Recent findingsClostridium difficile causes fulminant colitis in 3–8% of patients. Early predictors of disease include immunosuppression, hypotension, hypoalbuminemia, and a pronounced leukocytosis. In patients with fulminant colitis, early colectomy before vasopressor therapy is required and may improve survival. SummaryThe incidence and virulence of C. difficile infection are increasing. Antibiotic use and length of hospital stay correlate strongly with infection. Oral or intravenous metronidazole is the recommended first-line therapy, with discontinuation of systemic antibiotics if possible. Forty percent of patients may have a prolonged course and 20% will relapse despite adequate therapy. Fulminant colitis develops in 3–8% of patients; diagnosis can be difficult with diarrhea absent in 20% of the subgroup. Once diagnosed, subtotal colectomy with ileostomy is usually required. In patients with a marked leukocytosis or bandemia, surgery is advisable because the leukocytosis frequently precedes hypotension and the requirement for vasopressor therapy, which carries a poor prognosis.

Unique pattern of complications in elderly trauma patients at a Level I trauma center.

Background: Trauma centers are caring for increased proportions of elderly patients. Although age and Injury Severity Score are independently associated with mortality, trauma centers were originally designed to care for seriously injured patients without age-specific guidelines. We hypothesized that elderly patients would have different complication patterns than their younger counterparts. Methods: The trauma registry of an American College of Surgeons -verified Level I trauma center was queried for all patients older than 14 years admitted between January 2005 and December 2008. Mechanism, mortality, and complications were evaluated after dividing patients into eight age groups. Results: Of the 15,223 patients, 13% were elderly (≥65), and 86% were injured via a blunt mechanism. Increasing age correlated with fatality (all Injury Severity Scores), end-organ failure, and thromboembolic complications (deep venous thrombosis and coagulopathy). Analysis revealed a significant breakpoint at 45 years of age for mortality, decubitus ulcer, and renal failure (all p values <0.05). Infectious complications (sepsis, wound infection, and abscess) all peaked between 45 years and 65 years and then declined with increasing age. Conclusions: We document that elderly trauma patients suffer the same complications as their younger counterparts, albeit at a different rate. More importantly, we identified a “breakpoint” of increased risk of complications and mortality at greater than 45 years. Although the mechanisms behind these observations remain unknown, understanding their unique patterns may allow appropriate allocation of resources and focus research efforts on interventions that should improve outcomes. Level of Evidence: II.

Do not resuscitate status, not age, affects outcomes after injury: An evaluation of 15,227 consecutive trauma patients

BACKGROUND: Despite a well‐described association of age and injury with mortality and decreased functional status, inpatient mortality studies have traditionally not included analysis of do not resuscitate (DNR) status. We hypothesized that the increased likelihood of DNR status in older patients alters age‐adjusted mortality rates in trauma. METHODS: The trauma registry was queried for adult patients admitted to our Level I trauma center (January 2005–December 2008) and divided into eight age groups by decade. Ages 15–44 years were collapsed because of the lack of variation. We compared age, case fatality rate, and DNR status by univariate analysis and trends by [chi]2 (p < 0.05). RESULTS: Of the 15,227 adult patients admitted, 13% were elderly (>=65) and 7% died. DNR status was known in 75% of deaths, and 42% of those had active DNR orders on the chart at time of death. DNR likelihood increased with age (p < 0.05), from 5% to 18%. With DNRs excluded, mortality variability across all ages was markedly diminished (4–7%). CONCLUSION: DNR status among trauma patients varies significantly because of inconsistent implementation and meaning between hospitals, and successive decades are more likely to have an active DNR order at time of death. When DNR patients were excluded from mortality analysis, age was minimally associated with an increased risk of death. The inclusion of DNR patients within mortality studies likely skews those analyses, falsely indicating failed resuscitative efforts rather than humane decisions to limit care after injury. LEVEL OF EVIDENCE: Prognostic and epidemiologic study, level IV.

Pretreatment with bone morphogenetic protein-7 (BMP-7) mimics ischemia preconditioning following intestinal ischemia/reperfusion injury in the intestine and liver.

Intestinal ischemia/reperfusion (I/R) injury has been shown to cause intestinal mucosal injury and adversely affect function. Ischemic preconditioning (IPC) has been shown to protect against intestinal I/R injury by reducing polymorphonuclear leukocyte infiltration, intestinal mucosal injury, and liver injury, and preserve intestinal transit. Bone morphogenetic protein 7 (BMP-7) has been shown to protect against I/R injury in the kidney and brain. Recently, microarray analysis has been used to examine the possible IPC candidate pathways. This work revealed that IPC may work through upregulation of BMP-7. The purpose of this study was to examine if pretreatment with BMP-7 would replicate the effects seen with IPC in the intestine and liver after intestinal I/R. Rats were randomized to six groups: sham, I/R (30min of superior mesenteric artery occlusion and 6 h of R), IPC+R (three cycles of superior mesenteric artery occlusion for 4 min and R for 10 min), IPC+I/R, BMP-7+R (100 &mgr;m/kg recombinant human BMP-7), or BMP-7+I/R. A duodenal catheter was placed, and 30 min before sacrifice, fluorescein isothiocyanate-Dextran was injected. At sacrifice, dye concentrations were measured to determine intestinal transit. Ileal mucosal injury was determined by histology and myeloperoxidase activity was used as a marker of polymorphonuclear leukocyte infiltration. Serum levels of aspartate aminotransferase were measured at sacrifice to determine liver injury. Pretreatment with BMP-7 significantly improved intestinal transit and significantly decreased intestinal mucosal injury and serum aspartate aminotransferase levels, comparable to animals undergoing IPC. In conclusion, BMP-7 protected against intestinal I/R-induced intestinal and liver injury. Bone morphogenetic protein 7 may be a more logical surrogate to IPC in the prevention of injury in the setting of intestinal I/R.

Effects of anesthesia on lipopolysaccharide-induced changes in serum cytokines.

BACKGROUND The pathophysiology of sepsis is incompletely understood, however alterations in systemic inflammation and serum cytokines are thought to play a central role. In the rat, ketamine, but not isoflurane, prevents hepatic injury from lipopolysaccharide (LPS). The effect of these anesthetics on the systemic inflammatory response and other organs remains to be fully elucidated. We hypothesized that ketamine, but not isoflurane, would blunt the cytokine response to LPS administration. METHODS Male rats received no anesthesia, intraperitoneal ketamine (70 mg/kg), or inhalational isoflurane. One hour later, LPS (20 mg/kg, intraperitoneal) or saline was given for 5 hours and rats were killed. Gastric fluid volumes were determined as an index of gastric emptying. Serum was collected and cytokines measured via a multiplexed suspension immunoassay. RESULTS In nonanesthetized rats, LPS increased gastric luminal fluid accumulation and serum levels of proinflammatory cytokines when compared with saline controls. Anesthesia with either ketamine or isoflurane caused a significant reduction in LPS-induced changes in serum cytokines, although ketamine had a more dramatic reduction in tumor necrosis factor alpha levels than did isoflurane. Both anesthetics reduced the interleukin IL-6/IL-10 ratio in response to LPS when compared with LPS alone. Ketamine, but not isoflurane, prevented LPS-induced gastric luminal fluid accumulation. CONCLUSIONS These data indicate that both ketamine and isoflurane diminish the systemic inflammatory response to LPS in the rat as measured by serum cytokines and a reduced IL-6/IL-10 ratio. However, only ketamine improves LPS-induced gastric dysfunction, perhaps secondary to its ability to reduce serum tumor necrosis factor alpha levels more effectively.

Effect of NOS inhibition on rat gastric matrix metalloproteinase production during endotoxemia.

Matrix metalloproteinases (MMPs) degrade the extracellular matrix and contribute to LPS-induced gastric injury. MMPs are closely modulated by their activators, membrane type-MMP (MT-MMPs) and their endogenous inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). As LPS-induced gastric injury is mediated in part by iNOS, and NO modulates MMP production in vitro, we hypothesized that NOS inhibition would similarly modulate LPS-induced gastric MMP production. Therefore, the purpose of these studies was to compare the effects of selective and nonselective NOS inhibition on LPS-induced gastric MMP production. Methods Sprague-Dawley rats were given either the nonselective NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 5 mg/kg, s.c.), a selective iNOS inhibitor, aminoguanidine (45 mg/kg, i.p.) or l-N-iminoethyl-lysine (l-NIL; 10 mg/kg, i.p.), or vehicle 15 min before saline or LPS (20 mg/kg, i.p.) and killed 24 h after LPS administration. Stomachs were assessed for macroscopic injury (computed planimetry), and gastric mucosal MMP production was assessed by gelatin zymography, in situ zymography, and Western analysis for MMP-2, MT1-MMP, and TIMP-2. (n ≥ 4/group; ANOVA). Results Aminoguanidine treatment decreased LPS-induced macroscopic gastric injury as well as MMP-2 and MT1-MMP protein production while having no effect on TIMP-2 protein levels. l-NIL similarly attenuated the induction of MMP-2 and MT1-MMP by LPS. l-NAME failed to attenuate LPS induced gastric injury or MT1-MMP protein induction and increased MMP-2 levels. l-NAME similarly had no effect on gastric TIMP-2 production. Conclusions Selective iNOS inhibition decreases gastric MMP-2 activity after LPS administration, whereas nonselective inhibition increases MMP-2 levels. The ability of selective iNOS inhibition to ameliorate LPS-induced gastric injury may be due in part to its inhibition of active MMP-2 production, whereas nonselective NOS inhibitors increase MMP-2 levels and maintain gastric injury after LPS administration.

Ketamine-induced hepatoprotection: the role of heme oxygenase-1

Lipopolysaccharide (LPS) causes hepatic injury that is mediated, in part, by upregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Ketamine has been shown to prevent these effects. Because upregulation of heme oxygenase-1 (HO-1) has hepatoprotective effects, as does carbon monoxide (CO), an end product of the HO-1 catalytic reaction, we examined the effects of HO-1 inhibition on ketamine-induced hepatoprotection and assessed whether CO could attenuate LPS-induced hepatic injury. One group of rats received ketamine (70 mg/kg ip) or saline concurrently with either the HO-1 inhibitor tin protoporphyrin IX (50 micromol/kg ip) or saline. Another group of rats received inhalational CO (250 ppm over 1 h) or room air. All rats were given LPS (20 mg/kg ip) or saline 1 h later and euthanized 5 h after LPS or saline. Liver was collected for iNOS, COX-2, and HO-1 (Western blot), NF-kappaB and PPAR-gamma analysis (EMSA), and iNOS and COX-2 mRNA analysis (RT-PCR). Serum was collected to measure alanine aminotransferase as an index of hepatocellular injury. HO-1 inhibition attenuated ketamine-induced hepatoprotection and downregulation of iNOS and COX-2 protein. CO prevented LPS-induced hepatic injury and upregulation of iNOS and COX-2 proteins. Although CO abolished the ability of LPS to diminish PPAR-gamma activity, it enhanced NF-kappaB activity. These data suggest that the hepatoprotective effects of ketamine are mediated primarily by HO-1 and its end product CO.

Ketamine suppresses LPS-induced bile reflux and gastric bleeding in the rat.

BACKGROUND Although ketamine has many beneficial effects in a rat model of noninfectious inflammation with lipopolysaccharide (LPS), its effects on gut ileus are unknown. We hypothesized that ketamine would improve LPS-induced ileus and therefore examined its effects on gastric emptying and intestinal transit as well as duodenogastric bile reflux and associated gastric bleeding. METHODS Male rats received saline or ketamine (7 mg/kg ip) 1 hour before saline or LPS (20 mg/kg ip) for 5 hours. Thirty minutes before killing, rats received orogastric rhodamine B isothiocyanate-labeled dextran and 5 minutes later fluorescein isothiocyanate-labeled dextran via a duodenal catheter. GI contents were collected for dye, bile acid, and hemoglobin (index of bleeding) determinations. RESULTS LPS significantly impaired intestinal transit and increased duodenogastric bile reflux and gastric luminal hemoglobin content. Ketamine improved intestinal transit, prevented LPS-induced bile reflux, and diminished gastric bleeding. In mechanistic studies, ketamine also attenuated LPS-induced upregulation of the proinflammatory genes inducible nitric oxide synthase and cyclo-oxygenase-2 in the stomach but preserved expression of the anti-inflammatory gene heme-oxygenase-1 (Western blot). CONCLUSIONS These data suggest that ketamine may prevent LPS-induced gastric bleeding by decreasing bile reflux through improved intestinal transit or by local changes in nitric oxide, prostaglandin, and carbon monoxide metabolism.

A report on associations among gastric pH, bleeding, duodenogastric reflux, and outcomes after trauma.

BACKGROUND The pathogenesis of multiple organ failure (MOF) in trauma patients may involve the gastrointestinal tract, but its exact origins remain elusive. In a prospective study, the gastric fluid of major torso trauma patients was examined for evidence of duodenogastric reflux and potential gastric injury, and was compared with patient outcomes regarding MOF. METHODS Patient samples were collected daily for 4 days by nasogastric tube and analyzed for pH, hemoglobin, and bile acid. Blood was collected for analysis of C-reactive protein (CRP). Outcomes were recorded for the presence or absence of MOF. RESULTS The results showed that most patients exhibited alkaline gastric contents (pH >/=4.9) and elevated levels of hemoglobin immediately after the trauma. Although non-MOF patients demonstrated a decline of both mean gastric pH and bleeding by day 4, MOF patients maintained significant elevations in pH during this time period. Mean total bile acid levels were increased in all patients, signifying the presence of duodenogastric reflux. However, there were no clear differences in mean bile acid concentrations between MOF and non-MOF patients over time, although MOF patients tended to exhibit higher levels. All patients showed a progressive rise in serum CRP during the first 24 hours after trauma, which was maintained for 4 days. The initial rise in serum CRP in MOF patients was delayed compared with that in non-MOF patients. CONCLUSIONS We conclude that duodenogastric reflux occurs in trauma patients in the first few days after trauma and may contribute to elevated gastric pH and bleeding. Further study is needed to verify whether monitoring the gastric juice of trauma patients during the first several days of hospitalization, for alkaline pH and excessive blood in the gastric lumen, could lead to better assessments of patient status.