PAF-mediated Ca2+ influx in human neutrophils occurs via store-operated mechanisms.

Many inflammatory mediators activate neutrophils (PMN) partly by increasing cytosolic calcium concentration ([Ca2+]i). Modulation of PMN [Ca2+]i might therefore be useful in regulating inflammation after shock or sepsis. The hemodynamic effects of traditional Ca2+ channel blockade, however, could endanger unstable patients. Store-operated calcium influx (SOCI) is known now to contribute to Ca2+ flux in "nonexcitable" cells. Therefore, we studied the role of SOCI in human PMN responses to the proinflammatory ligand PAF. PMN [Ca2+]i was studied by spectrofluorometry with and without external calcium. We studied the effects o

Chemokine stimulation of human neutrophil [Ca2+]i signaling in biologic environments.

Clinical neutrophil (PMN) priming is the net result of multiple stimuli, with intracellular calcium ([Ca2+]i) being a key second messenger for PMN agonists such as the chemokines. Thus, [Ca2+]i measurement may be a robust tool for the assessment of global PMN activation. [Ca2+]i is difficult to measure in complex biologic environments, however, so data in this area are limited. We therefore developed an in vitro system to measure the effects of chemokines on PMN [Ca2+]i. PMN were isolated from volunteer blood. PMN [Ca2+]i responses to interleukin (IL)-8 and Growth-Related Oncogene (GRO)-alpha were studied by fura-2-acetoxymethyl ester fluorescence with or without reincubation in autologous plasma just prior to study. The effects of IL-8 and GRO-alpha on PMN [Ca2+]i at ascending doses, with or without plasma reincubation, given sequentially and in the presence or absence of extracellular calcium, were studied. PMN basal [Ca2+]i was increased by plasma, as were low-dose priming and higher-dose spike responses to IL-8. GRO-alpha caused a more pronounced priming of PMN [Ca2+]i than IL-8 at low doses, although significantly lower peak responses were observed with GRO-alpha than IL-8 at higher doses. Plasma suppressed both priming and spike responses to GRO-alpha. When given serially at clinically relevant agonist doses, GRO-alpha was permissive of IL-8 signaling, whereas IL-8 blocked GRO-alpha signaling. IL-8 generates high [Ca2+]i spikes using intracellular calcium stores only. GRO-alpha produces lower [Ca2+]i spikes despite using both intra- and extracellular stores. Plasma preincubation has profound effects on PMN [Ca2+]i responses to chemokines. These can be measured accurately, as described. In clinically relevant environments, IL-8 and GRO-alpha interact in a regulatory fashion. GRO-alpha may act as a priming agent, with IL-8 activating PMN functions requiring high [Ca2+]i. This cross-cooperation is probably terminated by IL-8 regulation of GRO-alpha activity at the C-X-C chemokine receptor 2.

Differential effects of acute hypoxia and endotoxin on the secretion and expression of bone marrow interleukin-1 and interleukin-6.

Hemorrhagic shock induces tissue hypoxia and has been demonstrated to alter the myelopoietic response to bacterial lipopolysaccharide (LPS). Interleukin-1 and interleukin-6 are important mediators of immunologic events after hemorrhagic shock. Bone marrow stroma release inflammatory cytokines, which may play a role in the regulation of myelopoiesis after injury. The aim of this study was to correlate cytokine gene expression with protein release and myelopoiesis by total bone marrow cells. The role of bone marrow stroma after exposure to hypoxia and lipopolysaccharide was also examined. BALB/c mice were designated as normoxia or hypoxia and total bone marrow cells were harvested. Hypoxia mice were exposed to 2 h of 5% O2/95% N2, and then returned to room air. Additional groups of mice were given LPS intraperitoneally. Bone marrow stroma, from BALB/c mice, was similarly designated. Myelopoiesis was assessed by growth of granulocyte-macrophage progenitor cells (CFU-GM). Interleukin-1 and interleukin-6 protein activity was assessed by bioassay. RNA was extracted from both total bone marrow cells and bone marrow stroma. By day 5, LPS alone resulted in a 93% increase in CFU-GM versus normoxia. Hypoxia and LPS exposure significantly decreased CFU-GM on days 1, 3, and 5. LPS alone induced an increase in interleukin-6. At 2, 6, and 24 h, hypoxia blunted interleukin-6 release in response to LPS. Hypoxia alone could not induce interleukin-6. However, hypoxia did induce interleukin-1 mRNA without the release of bioactive protein. In the remainder of groups, interleukin-1 protein levels and mRNA levels were correlated. Bone marrow stroma interleukin-1 and interleukin-6 protein activity was consistently correlated with that of total bone marrow. These data demonstrate that bone marrow cytokine production is differentially regulated by hypoxia. Hypoxia impairs interleukin-6 protein and mRNA in response to LPS, which may play a role in the suppression of myelopoiesis after shock. Also, bone marrow stroma plays an integral role in regulating myelopoiesis.

CXCR2 stimulation primes CXCR1 [Ca2+]i responses to IL-8 in human neutrophils.

Neutrophil (PMN) priming and subsequent responses to the IL-8 presented on pulmonary endothelial surfaces may be crucial determinants of the development of adult respiratory distress syndrome after injury. Elevated plasma ELR+ C-X-C chemokine (CXC) levels might contribute to PMN priming after trauma, but the role of CXCs in priming circulating PMNs is unstudied. We evaluated the interactions of IL-8 and GRO-alpha in priming human PMN calcium fluxes [Ca2+]i within circulatory environments. At physiologic concentrations, GRO-alpha primes PMN for IL-8 mediated [Ca2+]i mobilization, whereas IL-8 abolishes GRO-alpha responses. Repeated GRO-alpha exposures further enhance IL-8 responses. PMN priming for IL-8 responses in normal plasma was CXCR2 dependent. CXCR2 was more responsive than CXCR1 to low levels of IL-8, together suggesting that CXCR2 is the important CXC receptor at circulating (i.e., low) agonist concentrations. CXCR1 stimulation down-regulated CXCR2 surface expression, whereas CXCR2 stimulation upregulated CXCR1 expression. GRO-alpha/ CXCR2 signaling enhanced post-receptor IL-8 initiated PMN [Ca2+]i influx as well as efflux. Sufficient stimulation of the CXCR1 terminated this cooperative relationship by downregulating surface expression of CXCR2. This study is the first to report that at physiologic concentrations, C-X-C chemokines can act on circulating human PMNs as an integrated system where CXCR2 agonists, rather than cross-desensitizing CXCR1, act to enhance signaling of IL-8 at CXCR1 both by receptor and post-receptor mechanisms. Such CXCR2 mediated priming of CXCR1/ IL-8 interaction may enhance PMN attack on the lung after injury.

Injury-enhanced calcium mobilization in circulating rat neutrophils models human PMN responses.

G-protein coupled (GPC) chemoattractants are important neutrophil (PMN) activators in human shock and sepsis, acting in part by increasing cytosolic calcium ([Ca2+]i). Rats are widely used as laboratory models of shock and sepsis, but reports of [Ca2+]i flux in circulating rat PMN are rare. Moreover, the [Ca2+]i values reported often differ markedly from human systems. We developed study methods where basal [Ca2+]i values in circulating rat PMN were comparable to human PMN, but rat PMN still mobilized calcium poorly after stimulation. Trauma (laparotomy) did not change rat PMN basal [Ca2+]i, but induced brisk [Ca2+]i responses to chemokine and lipid mediators that approximated human PMN responses. This was associated with marked loading of microsomal calcium stores. Formyl peptides still mobilized calcium less well in rat than human PMN. Normal rat PMN appear to circulate in a less mature or primed form than human PMN. A very limited injury rapidly converts rat PMN to a more activated phenotype. PMN thus activated act quite similar to human PMN in terms of GPC receptor-mediated calcium mobilization. Trauma enhances rat PMN responses to GPC agonists at least in part by loading cell calcium stores.

Red cell deformability is an early indicator of infection.

Red blood cells (RBC) have been shown to become less deformable during infection. The RBC deformability index (DI) was measured within 24 hours of admission in 37 patients who had suffered trauma and every 48 to 72 hours thereafter while they were in the surgical intensive care unit to assess whether DI could be used as an early indicator of infection after injury. Infection was defined as a temperature of 101 degrees F or more and a white blood cell count of more than 12,000/cm3 associated with a positive culture. Eighteen patients developed an infection, and 19 patients did not. On day 1, both groups showed a significant decrease in DI, compared to controls (0.33 +/- 0.18 and 0.34 +/- 0.25 for patients with infection and patients with no infection vs 1.52 +/- 0.12 for control volunteers; p less than 0.05). In the group with no infection, the DI improved in 16 of 19 patients after injury; the DI in patients with infection continued to decrease in 17 of 18 patients. The decrease in DI occurred 4 +/- 2 days (range, 2 to 8 days) before the diagnosis of infection. No significant differences were apparent in the absolute white blood cell count between the group with infection and the group with no infection at any time after injury. Differences in maximal temperature were noted on day 3 and beyond; however, 30% of patients with no infection had a temperature of more than 101 degrees F for 7 days. These data show that trauma results in a significant decrease in RBC deformability and that serial changes in DI appeared to predict which patients would develop an infection and which patients would recover uneventfully. RBC deformability may be helpful in early detection of infection in patients who have suffered trauma.

The effect of cocaine on the physiologic response to hemorrhagic shock.

BACKGROUND: Bradycardia is thought to be an uncommon and abnormal response to acute blood loss. A review of trauma patients (n = 84) admitted during a 1-year period with a systolic blood pressure of less than 100 mm Hg revealed that 45% had relative bradycardia (heart rate < 100 beats/minute). Cocaine use was recorded more often in this group (76% versus 26%; p < 0.05) compared with patients with tachycardia (heart rate > or = 100 beats/minute). We investigated the effect of cocaine use on the response to acute blood loss in an animal model of hemorrhagic shock. METHODS: Rats were given intraperitoneal cocaine 20 mg/kg/day for 14 days (n = 10) or saline solution (n = 10). The rats were bled until 30% of their blood volume was shed; they were resuscitated 30 minutes later. RESULTS: Cocaine-treated rats showed a decreased 24-hour survival rate (50% versus 100%; p < 0.05), a relative bradycardic response compared to baseline heart rate (-8.9% +/- 6.4% versus 7.5% +/- 3.5%; p < 0.05), and a greater drop in mean arterial blood pressure (-55.5% +/- 4.8% versus -37.0% +/- 5.5%; p < 0.05) by 5 minutes of shock. Cocaine-treated rats were more acidotic after shock compared to controls (pH 7.36 +/- 0.03 versus 7.44 +/- 0.02; p < 0.05). CONCLUSIONS: Cocaine had a deleterious effect on experimental hemorrhage. The bradycardic response observed in our trauma patients may be due, in part, to cocaine abuse, and we postulate that chronic cocaine use alters the normal adrenergic response to blood loss.

Hemorrhagic shock inhibits lipopolysaccharide-induced myelopoiesis in both germ-free and conventional rats.

BACKGROUND: Bacterial translocation has been implicated in the alteration of the immune response after shock and trauma. This study examined the effect of bacterial translocation on myelopoiesis after hemorrhagic shock in germ-free and conventional rats. METHODS: Awake, unrestrained germ-free and conventional rats were bled to a mean arterial pressure of 30 mm Hg until the animal required infusion of 10% of the shed blood. Rats were resuscitated with shed blood and crystalloid. Sham rats were catheterized but not bled. Twenty-four hours after shock or sham, rats were administered lipopolysaccharide 100 micrograms or saline intraperitoneally. Twenty-four hours later, bone marrow cells were cultured for growth of granulocyte-macrophage colony-stimulating factor (CFU-GM). RESULTS: Lipopolysaccharide increased the number of CFU-GM/femur in sham germ-free rats (801 +/- 129 versus 455 +/- 110; p less than 0.05) and conventional rats (1458 +/- 200 versus 492 +/- 59; p less than 0.05) compared with saline-treated rats. In contrast, hemorrhagic shock inhibited lipopolysaccharide-induced CFU-GM growth in both germ-free and conventional rats. Shock, itself, was a stimulus for CFU-GM growth in germ-free but not conventional rats. Bone marrow white blood cell counts were unaffected by shock, lipopolysaccharide administration, or the germ-free state. CONCLUSIONS: Hemorrhagic shock inhibited lipopolysaccharide-induced CFU-GM proliferation independent of the germ-bearing status of the rat, and bacterial translocation exerted no influence on myelopoietic dysfunction after hemorrhagic shock.

Integrated stimulation by CXC chemokines enhances PMN [Ca2+]i signaling in trauma and adult respiratory distress syndrome.

BACKGROUND: Trauma and adult respiratory distress syndrome (ARDS) are associated with increased CXC chemokine (CXC) activity. CXCs such as interleukin (IL)-8 activate polymorphonuclear neutrophils (PMNs) in the lung by means of calcium signals ([Ca2+]i). We studied CXC effects on PMN [Ca2+]i in ARDS and trauma. METHODS: Isolated PMNs were loaded with Fura-2 dye. Normal PMNs were incubated in ARDS plasma or volunteer plasma, with or without blocking antibodies to IL-8, growth-related oncogene alpha (GRO-alpha), or both (n = 6 pairs), and then stimulated with 1 to 10 nmol/L IL-8. PMNs from trauma patients or volunteers (n = 10 pairs) were stimulated with GRO-alpha, or with sequential GRO-alpha/IL-8. [Ca2+]i was measured with spectrofluorometry. RESULTS: [Ca2+]i responses to IL-8 were higher after being incubated in ARDS plasma than in volunteer plasma (251 +/- 33 vs 218 +/- 33 nmol/L, P = .03). Blockade of GRO-alpha or IL-8 reversed ARDS plasma effects. After GRO-alpha/IL-8, PMNs from trauma patients demonstrated more Ca2+ store release than did PMNs from volunteers (235 +/- 13 vs 170 +/- 10 nmol/L, P < .01). Conversely, PMNs from trauma patients lost receptor-operated Ca2+ influex to GRO-alpha. CONCLUSIONS: In traumatic ARDS, plasma CXCs prime PMNs for higher [Ca2+]i flux, making PMN activation more likely. IL-8 and GRO-alpha interact to modulate these PMN [Ca2+]i responses.

Interferon-gamma reverses bone marrow inhibition following hemorrhagic shock.

Hemorrhagic shock has been demonstrated to alter the myelopoietic response to bacterial lipopolysaccharide. Interferon-gamma has been shown to improve the immune response following experimental shock and injury; however, its effect on myelopoiesis is controversial. This study was performed to determine whether treatment with interferon-gamma will improve the bone marrow response to lipopolysaccharide after hemorrhagic shock. Rats subjected to either shock or a sham procedure were allocated into three groups: (1) control rats received no further treatment; (2) lipopolysaccharide-treated rats received saline for 3 days and then were challenged with lipopolysaccharide to stimulate myelopoiesis; and (3) interferon-treated rats received interferon-gamma (7500 U subcutaneously 1 hour after shock and then every day for 3 days) and lipopolysaccharide as in group 2. Serum colony-stimulating factor levels were measured 6 hours and bone marrow white blood cell count and granulocyte-macrophage colony-forming units (CFU-GM) were measured 24 hours following lipopolysaccharide administration. In sham-treated rats, lipopolysaccharide increased CFU-GM 77% compared with controls. In contrast, treatment with lipopolysaccharide decreased CFU-GM 43% following shock. Treatment with interferon-gamma increased CFU-GM in all animals and reversed the decline in CFU-GM seen in shocked lipopolysaccharide-treated animals. Serum colony-stimulating factor levels were unaffected by either shock or interferon-gamma administration. These data demonstrate that interferon-gamma exerts a stimulatory effect on bone marrow following shock and restores the myelopoietic response to lipopolysaccharide.

Interferon gamma and tumor necrosis factor alpha. Use in gram-negative infection after shock.

Shock increases the propensity to develop infection after injury or operation. This study evaluated the effect of cefoxitin, interferon gamma (INF-gamma), and tumor necrosis factor alpha (TNF-alpha) on the development of a polymicrobial soft-tissue infection. After sham operation or hemorrhagic shock and resuscitation, Sprague-Dawley rats were inoculated with 1 x 10(8) Escherichia coli and 1 x 10(9) Bacteroides fragilis in a 5% fecal suspension. Animals received either no treatment, cefoxitin, recombinant rat INF-gamma, recombinant human TNF-alpha, or cefoxitin/cytokine combinations. Cefoxitin reduced abscess size by 57% in animals without shock but only by 26% after shock. Although neither INF-gamma nor TNF-alpha alone had a salutary effect when given with cefoxitin in animals after shock, INF-gamma and TNF-alpha reduced abscess size by 50% and 55%, respectively. These results suggest that INF-gamma and TNF-alpha may be useful to reduce the severity of mixed gram-negative infections after shock with bacterial contamination.

Tuberculin screening of trauma admissions at a university hospital. A preventive strategy.

OBJECTIVE: To determine the prevalence of tuberculosis (TB) infection in our trauma service population, namely, those patients who had positive Mantoux (purified protein derivative [PPD] [tuberculin]) tests. DESIGN: Prospective study. SETTING: Trauma service at a university hospital in Newark, NJ. PATIENTS AND METHODS: During a 9-month period, 110 admitted trauma patients underwent screening for TB. Of these patients, 20 had undergone recent PPD tests in the last 6 months, of which nine were positive. The remaining 90 patients underwent PPD and delayed-type hypersensitivity skin tests (anergy panel); five patients were unavailable for follow-up. The patients also answered questions regarding human immunodeficiency virus status, risk factors for TB infection, and clinical symptoms. RESULTS: The mean age of the study group was 34 years (age range, 13 to 69 years). Eighty-four percent of these patients were males who belonged to the high-risk socioeconomic, racial, and ethnic groups (poor, non-white). The tests for 15 patients (17%) were newly discovered to be positive for PPD. Eleven percent of the patients with negative PPD tests were anergic, thus raising the percentage of patients with positive PPD tests to 20%. The human immunodeficiency virus status was known in only 41% of the total patients. All patients with positive PPD tests had a chest x-ray film performed; of these patients, positive findings for TB were determined for one patient. Another patient had evidence of abdominal TB at laparotomy. All patients with positive PPD tests were given appointments in the pulmonary clinic for follow-up, and only three of 15 patients kept their appointments. CONCLUSIONS: Patients who were admitted to the trauma service were predominantly young males from high-risk groups with a high incidence of TB infection. Their admission to the trauma service was a unique opportunity for screening and implementing existing preventive programs.

Depressed interferon gamma production and monocyte HLA-DR expression after severe injury.

Monocyte HLA-DR antigen expression and mitogen-stimulated interferon gamma production were measured sequentially on days 1, 3, 7, 14, and 21 after admission in 20 multiply injured patients (mean Injury Severity Score, 33). Ten patients recovered uneventfully and ten developed a major infection, three of whom died. Trauma resulted in immediate and profound depression of both interferon gamma production and monocyte HLA-DR antigen expression compared with controls. Interferon gamma remained below control levels for all days on which it was measured in all patients. In uninfected patients, interferon gamma production began to recover after day 7 and interferon gamma levels on day 21 were greater than on all other days. Monocyte HLA-DR antigen expression returned to normal between days 7 and 14 in uninfected patients, despite subnormal production of interferon gamma. Failure to increase interferon gamma production and monocyte HLA-DR antigen expression was associated with an episode of major infection. We postulate that stimulation of the immune system early after injury may reverse the defects reported and decrease the incidence of infection after severe trauma.

Interferon gamma administration increases monocyte HLA-DR antigen expression but not endogenous interferon production.

OBJECTIVE: To determine the effect of the adjuvant administration of interferon gamma on monocyte HLA-DR antigen expression and mitogen-stimulated interferon gamma production following injury. DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: University Hospital, Newark, NJ, a level I trauma center. PATIENTS: Persons older than 16 years with an Injury Severity Score greater than 20 and documented bacterial contamination at the time of injury (N = 98). INTERVENTIONS: Recombinant human interferon gamma (n = 46; 0.1 mg subcutaneously) or placebo (n = 52) was given for 10 days following injury. OUTCOMES: Incidence of major infection, monocyte and lymphocyte cell surface antigen expression, and interferon gamma production at multiple time points following injury. RESULTS: Peripheral monocyte HLA-DR was measured as percent of cells staining positive and as mean channel fluorescence. Both values were significantly increased in the interferon gamma group compared with the placebo group on days 3, 5, 8, and 11. The incidence of major infection was unaffected by interferon gamma administration. Infection decreased percent of HLA-DR-positive monocytes and mean channel fluorescence as compared with noninfected patients on postinjury days 8 and 11 in the placebo group but not in the interferon gamma group. Interferon gamma production improved from 3 +/- 3 U/mL on day 1 to 15 +/- 10 U/mL by day 30 but was always significantly lower than normal (25 +/- 3 [mean +/- SD] U/mL). Interferon gamma production was unaffected by either infection or interferon gamma administration. CONCLUSIONS: Interferon gamma administration after injury stimulated monocyte HLA-DR antigen expression and density but failed to improve interferon gamma production, a T-cell-mediated function. The incidence of infection was not decreased by the administration of interferon gamma for 10 days. Improvement in monocyte HLA-DR antigen expression did not correlate with a global restoration of immune function, and other interventions will be necessary to decrease infection after injury.

Suppression of natural killer cell activity in patients with fracture/soft tissue injury.

BACKGROUND: Natural killer cells (NKCs) participate in "innate" cell-mediated immunity. Fracture/soft tissue injuries are cytokine rich and may influence cell-mediated immunity. OBJECTIVE: To study the effects of fracture cytokines on NKC function. DESIGN: A case-control study. SETTING: A level I trauma center and laboratory in a university medical center. PARTICIPANTS: Patients requiring open fracture fixation and healthy volunteers. INTERVENTIONS: Fracture supernatants and peripheral plasma were collected during open fracture fixation. Volunteer mononuclear cells were used as effector (NKC) sources. Mononuclear cells were preincubated with fracture supernatants, paired peripheral plasma, or normal plasma under various conditions. MAIN OUTCOME MEASURES: Natural killer cell lysis of K562 target cells was assessed by chromium 51 release. RESULTS: Fracture supernatants suppressed NKC function more rapidly than peripheral plasma. Fracture supernatants from 1 to 4 days after injury were most suppressive. Inactivation of complement and reactive oxygen species failed to restore lysis. Neutralizing antibodies to interleukin 4 and interleukin 10 further suppressed lysis. Antibodies to transforming growth factor beta1 failed to restore lysis. The addition of interferon gamma did not restore lysis but the addition of interleukin 12 did. CONCLUSIONS: Fracture supernatants and peripheral plasma from patients with fractures suppress NKCs. The responsible mediators may be concentrated in fracture/soft tissue injuries. Responses to manipulation of the cytokine environment suggest that fracture cytokines may impair cooperation between NKCs and accessory cells.

Treatment of pneumonia in mechanically ventilated trauma patients. Results of a prospective trial.

OBJECTIVES: To determine the efficacy and magnitude of associated adverse effects of 2 different antibiotic regimens for the treatment of pneumonia in intubated surgical patients and to assay and compare blood samples and bronchoalveolar lavage fluid with respect to some host-defense parameters, especially in patients with unilateral pneumonia. DESIGN: Randomized, prospective, unblinded clinical comparison of 2 treatment arms with respect to intent to treat and clinical and microbiologically evaluable patients. SETTING: Six university surgical services in teaching hospitals with modern and well-staffed intensive care units. INTERVENTIONS: The consistency and objectively of the diagnosis of pneumonia was improved by the use of a grid of diagnostic parameters. Aggressive mechanical approaches to pneumonia in intubated surgical patients were supplemented by therapeutic use of aztreonam and vancomycin hydrochloride or combined imipenem and cilastatin sodium. RESULTS: Patients randomized to the aztreonam-vancomycin group were somewhat more ill, fared slightly better, and had fewer serious drug-related side effects than did those treated with imipenem-cilastatin (all P > .05). Immunologic parameters assessed by evaluation of bronchoalveolar lavage fluid showed differences between infected pulmonary lobes and noninfected ones; some changes were also noted in patients who recovered compared with those whose pneumonia persisted or recurred. CONCLUSIONS: Clinical studies of pneumonia in surgical patients need to be stratified to assure comparability, to identify patients in whom treatment is likely to fail, and to display differences between more and less effective therapies. Studies of blood and bronchoalveolar lavage samples showed that certain local and systemic immunologic parameters correlate with clinical status and outcome.

Effect of hypoxia on the hematopoietic and immune modulator preprotachykinin-I.

OBJECTIVES: To determine the effect of hypoxia on bone marrow mononuclear cells (BMMCs) and their ability to proliferate into granulocyte-macrophage colony-forming units (CFU-GMs) and erythroid burst-forming units (BFU-Es) and to determine the role of the neuroimmune and hematopoietic mediator, substance P. DESIGN: Controlled in vitro study. SETTING: University research laboratory. MATERIALS: Bone marrow aspirates were obtained from the posterior iliac crests of healthy volunteers after obtaining informed consent. INTERVENTIONS: The BMMCs were divided into the following groups: (1) normoxia, (2) two hours of hypoxia, and (3) six hours of hypoxia. Additional BMMCs were purified before the period of hypoxia, while others were incubated with neurokinin (NK) receptor antagonists. In other experiments, bone marrow stroma was grown to confluence and randomized to the following groups: (1) normoxia, (2) hypoxia, (3) normoxia and interleukin (IL) 1, and (4) hypoxia and IL-1. All groups were cultured for 2, 6, 12, or 24 hours. MAIN OUTCOME MEASURES: The formation of CFU-GMs and BFU-Es was measured after 10 to 14 days of incubation of the BMMCs. The messenger RNA of the preprotachykinin-I (PPT-I) gene and the NK-1 and NK-2 receptors was detected by using semiquantitative reverse transcriptase-polymerase chain reaction or Northern blot analysis on bone marrow stroma. The immunoreactivity of substance P in bone marrow stroma was measured by competitive enzyme-linked immunosorbent assay. RESULTS: Hypoxia resulted in a 110% increase in the number of CFU-GMs and a 78% increase in the number of BFU-E colonies at 6 hours (both P<.05). Elimination of the stromal elements by purification abrogated the increase in colony formation to nonhypoxic levels. Hypoxia induced PPT-I gene expression at 24 hours; however, no PPT-I expression was found in the hypoxic group incubated with IL-1. The receptor, NK-1, was found to be equal in both hypoxic groups; NK-2 was found to have a 4-fold increase in the hypoxia and IL-1 group over the hypoxia alone group and normoxia and IL-1 group. The levels of substance P immunoreactivity were found to be similar in all groups. Incubation of BMMCs with NK receptor antagonists to NK-1 alone or NK-1 and NK-2 decreased the number of CFU-GM and BFU-E colonies similar to the level in controls. CONCLUSIONS: These results indicate that hypoxia has a role in the proliferation and control of CFU-GMs and BFU-Es. This control seems to be mediated through the bone marrow stroma and modulated by NK receptors and induction of PPT-I. The neuropeptide, substance P, probably has a role but is clearly not the only mediator involved.

Role of interleukin 8 in the genesis of acute respiratory distress syndrome through an effect on neutrophil apoptosis.

OBJECTIVE: To evaluate the role of interleukin 8 (IL-8) in the regulation of neutrophil (PMN) apoptosis in normal plasma and plasma from patients with early, fulminant acute respiratory distress syndrome (ARDS). DESIGN: Experimental study using cultured human PMNs. SETTING: University hospital, level I trauma center. PARTICIPANTS: Plasma was obtained from 6 patients with early, fulminant posttraumatic ARDS (mean Injury Severity Score, 26). All samples were drawn within 24 hours after injury. Plasma was also taken from 13 healthy control subjects. These controls were also used as sources of PMNs. MAIN OUTCOME MEASURES: Effect of early, fulminant ARDS and normal plasma on spontaneous apoptosis, CD16, and CD11-b expression in PMNs in vitro; levels of IL-8 in plasma; correlation of extracellular IL-8 concentration with rate of PMN apoptosis; and effect of IL-8 blockade on PMN apoptosis, CD16, and CD11-b expression in ARDS and normal plasma. RESULTS: Plasma from patients with early, fulminant ARDS inhibited spontaneous PMN apoptosis at 24 hours (35%+/-5% vs 54%+/-5%; P=.01). Neither CD16 nor CD1l-b differed significantly between the 2 groups. The mean plasma level of IL-8 in patients with early, fulminant ARDS was 359+/-161 pg/mL vs 3.0+/-0.4 pg/mL in healthy controls (P<.05). Interleukin 8 inhibited apoptosis in plasma-free medium at low doses (1-50 pg/mL) but had no significant effect at higher doses (100-5000 pg/mL) (P<.05). Interleukin 8 blockade with monoclonal antibody suppressed apoptosis in normal plasma (28%+/-5% with monoclonal antibody vs 51%+/-5% without monoclonal antibody; P=.008) but not in plasma from patients with early, fulminant ARDS (29%+/-5% with monoclonal antibody vs 34%+/-6% without monoclonal antibody; P=.67). It had no effect on CD16 or CD11-b expression in either plasma. CONCLUSIONS: Plasma from patients with early, fulminant ARDS contains soluble factors that inhibit PMN apoptosis in vitro. Low levels of IL-8 inhibit PMN apoptosis in normal plasma. Although plasma levels of IL-8 are markedly elevated in early, fulminant ARDS, IL-8 is not directly responsible for the antiapoptotic effect of plasma from patients with early, fulminant ARDS.

Ureteral trauma: preoperative studies neither predict injury nor prevent missed injuries.

BACKGROUND: Ureteral injuries are uncommon, and the necessity, accuracy, and optimal use of perioperative testing remains unknown. Delays in diagnosis have also been associated with significant morbidity, including loss of renal function. STUDY DESIGN: The records of all patients (n = 20) admitted with ureteral injuries to two Level I trauma centers during a 5-year period were reviewed. Data collected included patient demographics, mechanism of injury, degree of associated injuries, and presence of gross or microscopic hematuria. The use of any pre- or intraoperative testing was specifically noted. The location of the ureteral injury was obtained from the operative notes. The morbidity and mortality associated with ureteral injuries in the primarily diagnosed and the delayed groups were assessed. Presenting signs and symptoms, diagnostic testing, and the urologic management of the patients in the delayed group were reviewed. RESULTS: All patients were men whose ages ranged from 15 to 72 years, with a mean age of 29. The mechanisms of injury were gunshot wounds in 15, stab wounds in 4, and blunt vehicular trauma in 1. Excluding other urologic injuries, the incidence of hematuria related to the ureteral injury alone was 53%. A total of 10 pre- and intraoperative studies were performed, only 2 demonstrated the ureteral injury. Seventeen patients had their injuries diagnosed primarily. In this group, the ureter was repaired by suturing and stenting in 12, suturing without a stent in 1 and ureterocystostomy in 4. Delayed diagnosis of their ureteral injuries occurred in three patients. All three missed injuries occurred in the upper portion of the left ureter. All ureters were successfully repaired. There were no mortalities in this group, nor did any patient require a nephrectomy. CONCLUSIONS: Direct visualization of the injury is the best and most accurate diagnostic modality in ureteral trauma. These results reinforce that a thorough exploration of all retroperitoneal hematomas after penetrating trauma remain an integral part of the total abdominal exploration for trauma.

The utility of venous lactate to triage injured patients in the trauma center.

BACKGROUND: Field triage criteria for trauma patients results in over-triage rates of 30% to 50% to achieve under-triage rates of 10%. This large number of patients may stress trauma center resources. Elevated arterial lactate (ALAC) levels have been shown to be a marker of serious injury but the need for arterial sampling limits the utility of the determination. The goal of this study was: 1) to determine the correlation between venous lactate (VLAC) and ALAC; 2) to determine whether VLAC could identify those patients with serious injuries; and 3) to compare an elevated VLAC level against standard triage criteria (STC) in their ability to identify major injury. STUDY DESIGN: Arterial and venous samples for blood gas and lactate analyses were obtained in 375 patients within 10 minutes of patient arrival to the trauma center. Arterial and venous samples were drawn within 2 minutes of each other, placed on ice, and analyzed within 10 minutes of sampling. The location of sampling was left to physician discretion. Data collected included injury mechanism, demographics, admission vital signs, emergency department disposition, length of stay, and injury severity scores (ISS). Admission to the ICU, need for emergency operation, length of stay, and death were noted. Emergency medical service staff were queried to determine which standard triage criteria (STC) were fulfilled. RESULTS: The mean ALAC was 3.11 mmol/L (SD 3.45, 95% confidence interval [CI] 2.67 to 3.55) and mean VLAC was 3.43 mmol/L (SD 3.41, 95% CI 2.96 to 3.90). There was no significant difference between ALAC and VLAC. The correlation between ALAC and VLAC was 0.94 (95% CI 0.94 to 0.96, p = 0.0001). An elevated VLAC predicted moderate to severe injury and there was a significant association between an increased lactate and maximum Abbreviated Injury Score (AIS) of 4 and 5 (ANOVA, F = 8.26, p < 0.001). Patients with VLAC > or =2 mmol/L had significantly increased relative risks of ISS > or = 13, death, admission to the ICU, and length of stay > 2 days. In comparison with STC, a VLAC > or = 2 mmol/L decreased undertriage in patients with ISS > or = 13 by one half (11% versus 24%) for patients with ISS > or = 13 and decreased over-triage by 28% (46% versus 64%). These data were most pronounced for patients injured in motor vehicle collisions. CONCLUSIONS: VLAC is an excellent approximation for ALAC. A VLAC > or = 2 mmol/L appears to predict an ISS > or = 13, the need for ICU resources, and prolonged hospital stays. VLAC was significantly better than STC in all patients and was most useful in victims of blunt trauma, especially motor vehicle collisions.