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Objectives To build and test cardiac arrest prediction models in a PICU, using time series analysis as input, and to measure changes in prediction accuracy attributable to different classes of time series data. Design Retrospective cohort study. Setting Thirty-one bed academic PICU that provides care for medical and general surgical (not congenital heart surgery) patients. Subjects Patients experiencing a cardiac arrest in the PICU and requiring external cardiac massage for at least 2 minutes. Interventions None. Measurements and main results One hundred three cases of cardiac arrest and 109 control cases were used to prepare a baseline dataset that consisted of 1,025 variables in four data classes: multivariate, raw time series, clinical calculations, and time series trend analysis. We trained 20 arrest prediction models using a matrix of five feature sets (combinations of data classes) with four modeling algorithms: linear regression, decision tree, neural network, and support vector machine. The reference model (multivariate data with regression algorithm) had an accuracy of 78% and 87% area under the receiver operating characteristic curve. The best model (multivariate + trend analysis data with support vector machine algorithm) had an accuracy of 94% and 98% area under the receiver operating characteristic curve. Conclusions Cardiac arrest predictions based on a traditional model built with multivariate data and a regression algorithm misclassified cases 3.7 times more frequently than predictions that included time series trend analysis and built with a support vector machine algorithm. Although the final model lacks the specificity necessary for clinical application, we have demonstrated how information from time series data can be used to increase the accuracy of clinical prediction models.

BACKGROUND: Acute chest syndrome (ACS) is a leading cause of hospitalization and death of children with sickle cell disease (SCD). An evidence-based ACS/SCD guideline was established to standardize care throughout the institution in February 2008. However, by the summer of 2009 use of the guideline was inconsistent, and did not seem to have an impact on length of stay. As a result, an implementation program was developed. OBJECTIVE: This quality-improvement project evaluated the influence of the development and implementation of a clinical practice guideline for children with SCD with ACS or at risk for ACS on clinical outcomes. METHODS: Clinical outcomes of 139 patients with SCD were evaluated before and after the development of the implementation program. Outcomes included average length of stay, number of exchange transfusions, average cost per SCD admission, and documentation of the clinical respiratory score and pulmonary interventions. RESULTS: Average length of stay decreased from 5.8 days before implementation of the guideline to 4.1 days after implementation (P = .033). No patients required an exchange transfusion. Average cost per SCD admission decreased from $30 359 before guideline implementation to $22 368. Documentation of the clinical respiratory score increased from 31.0% before implementation to 75.5%, which is an improvement of 44.5% (P < .001). Documentation of incentive spirometry and positive expiratory pressure increased from 23.3% before implementation to 50.4%, which is an improvement of 27.1% (P < .001). CONCLUSIONS: Implementation of a guideline for children with SCD with ACS or at risk for ACS improved outcomes for patients with SCD.

Objectives To review the epidemiology of pediatric multiple organ dysfunction syndrome (MODS) and summarize current concepts regarding the pathophysiology of shock, organ dysfunction, and nosocomial infections in this population. Data source A MEDLINE-based literature search using the keywords MODS and child, without any restriction to the idiom. Main results Critically ill children may frequently develop multisystemic manifestations during the course of severe infections, multiple trauma, surgery for congenital heart defects, or transplantations. Descriptive scores to estimate the severity of pediatric MODS have been validated. Young age and chronic health conditions have also been recognized as important contributors to the development of MODS. Unbalanced inflammatory processes and activation of coagulation may lead to the development of capillary leak and acute respiratory distress syndrome. Neuroendocrine and metabolic responses may result in insufficient adaptive immune response and the development of nosocomial infections, which may further threaten host homeostasis. Conclusions Over the last 20 yrs, there has been an increasing knowledge on the epidemiology of pediatric MODS and on the physiologic mechanisms involved in the genesis of organ dysfunction. Nevertheless, further studies are needed to more clearly evaluate what is the long-term outcome of pediatric MODS.

OBJECTIVE To review whether induced hypothermia after traumatic brain injury affects morbidity and mortality based on the results of two meta-analyses. DESIGN Critical appraisals of McIntyre et al: Prolonged therapeutic hypothermia after traumatic brain injury in adults: A systematic review. JAMA 2003; 289:2992-2999, and Henderson et al: Hypothermia in the management of traumatic brain injury: A systematic review and meta-analysis. Intensive Care Med 2003; 29:1637-1644. FINDINGS Both meta-analyses included trials of adult patients with severe traumatic brain injury randomized to induced hypothermia or normothermia and evaluated risk of death and poor neurologic outcomes. McIntyre et al. found the overall relative risk of mortality with induced hypothermia to be 0.81 (95% confidence interval 0.69-0.96). By designing a priori analyses, these authors also found that the relative risk of death was reduced in patients cooled for >48 hrs, and the risk of poor neurologic outcome was reduced with all durations of cooling, cooling to 32-33 degrees C, and rewarming in

Shiga toxin producing Escherichia coli (STEC) are noninvasive enteric pathogens that may cause hemorrhagic colitis (HC) and diarrhea-associated hemolytic uremic syndrome (D+ HUS). We hypothesized that development of D+ HUS is associated with increased serum procalcitonin (PCT) levels. PCT was measured by an immunoluminometric assay in 113 patients. Concentrations of PCT were different in normal controls, disease control groups (rotavirus enteritis, HC due to non-STEC pathogens, chronic renal failure), and children with uncomplicated O157:H7 HC or D+ HUS. Children with D+ HUS showed higher PCT levels than those with uncomplicated O157:H7 HC, and increased concentrations were noted in cases requiring peritoneal dialysis. Severely increased concentrations were observed in children with D+ HUS on d 5 or 6 after the onset of enteritis, whereas serial measurements in those with uncomplicated O157:H7 HC remained within the normal range throughout the first week of illness. PCT was correlated with serum concentrations of lipopolysaccharide (LPS)-binding protein and serum levels of alanine aminotransferase. Using two separate sets of real-time PCR primers, we were unable to detect elevated PCT mRNA transcripts in nonadherent undifferentiated (monocytic) or differentiated (macrophage-like) THP-1 cells stimulated with purified Shiga toxin-1 and/or LPS. Our data show that serum levels of PCT are associated with the severity of illness in children with D+ HUS. Further studies are needed to determine the role of PCT in the pathogenesis of thrombotic microangiopathy associated to childhood D+ HUS.

Innate and adaptive immunity are required for effective control of infection. Numerous breakthroughs have been achieved in the last 15 years with regard to the functioning of the innate immune system. This article focuses on new paradigms of microorganism recognition, discusses recently described (or rediscovered) cytokines that provide further insight into the development of sepsis, and reviews both pro- and anti-inflammatory pathways for control of infection. Finally, it discusses what has and has not worked with regard to controlling inflammatory pathways in septic patients.

Delays in leukocyte localization likely contribute to diminished host defense in neonates. Understanding the processes that may be affected has been hampered by the lack of suitable developmental models. Using intravital microscopy, we directly examine leukocyte recruitment in a rabbit pup model. In response to intraperitoneal interleukin (IL)-1β, there were one-third as many leukocytes that arrested in pup mesenteric vessels and emigrated compared with adult vessels, although leukocyte flux was not different. Leukocyte rolling velocity in pups was one-half that in adults. In response to surgical trauma alone, the number of arrested pup cells was 15% that of adult cells, although again leukocyte flux was not different. An anti-L-selectin antibody inhibited rolling significantly by 60 min for both pups and adults. The effect on arrest and emigration occurred at significantly earlier times, although the effect was less in rabbit pups. A primary defect in leukocyte emigration in the rabbit pup appears to be a failure of the cell to transition efficiently from rolling to arrest. L-selectin-dependent adhesion and emigration are decreased, rolling is not, suggesting that at least part of the defect is due to events downstream of the initial tether.

Fewer than 10% of children with Escherichia coli O157:H7 enteritis develop hemolytic-uremic syndrome (HUS).To determine whether circulating leukocytes are independent risk markers of developing HUS during E. coli O157:H7 enteritis.We reviewed the charts of all children with culture-proved E. coli O157:H7 infections seen at Sainte-Justine Hospital between 1987 and 1997. Epidemiologic data, laboratory indices and circulating leukocytes counts were noted. HUS diagnosis was validated with independent HUS patient lists from the pediatric nephrology services of tertiary care hospitals in the Montreal metropolitan area. The date of onset of enteritis was determined by two independent observers. Leukocyte counts were compared among the following independent groups: (1) uncomplicated O157:H7 enteritis (Group 1); (2) O157:H7 enteritis with the subsequent development of HUS (Group 2); (3) HUS already present at the time of medical consultation (Group 3).There were 369 children with E. coli O157:H7 infection. A complete blood count was not performed in 114 (31%) patients. Observers disagreed on the date of onset of gastroenteritis in 34 (9%) children only (kappa 0.92). The study population thus included 221 patients: Group 1, n = 161; Group 2, n = 27; and Group 3, n = 33. Patients developing HUS (Group 2) presented greater total leukocyte (P0.008), polymorphonuclear (P0.008) and monocyte (P0.07) counts than those with an uncomplicated course (Group 1). Logistic regression analysis showed that young age [odds ratio (OR), 0.98; 95% confidence interval (CI), 0.96 to 0.99], duration of enteric prodromeor =3 days (OR 4.8, 95% CI 1.13 to 20.7) and initial leukocytosis (OR 1.22, 95% CI, 1.11 to 1.35) were independent predictors of HUS.Based on the variables identified above, further studies are needed to determine whether the inflammatory response of the host represents only a marker of the severity of gastrointestinal infection or whether, alternatively, it is a pathophysiologic factor that leads to HUS.

Previously we had determined that neonatal neutrophils had decreased interaction with monolayers expressing P-selectin compared to adult cells. In this study we examined the function of neonatal P-selectin glycoprotein ligand-1 (PSGL-1). A rabbit polyclonal antibody directed against the amino terminus of human PSGL-1 was produced and purified (3RB-PSGL-1). Neonatal neutrophils expressed the epitope recognized by 3RB-PSGL-1 and expression was decreased compared with adult neutrophils (20%, P < 0.05). In addition neonatal neutrophils had decreased interaction with Chinese hamster ovary (CHO)-P-selectin under both shear conditions and static adhesion (P < 0.05). Treatment of both neonatal and adult neutrophils with 3RB-PSGL-1 similarly inhibited the interaction with P-selectin monolayers under shear conditions, effects similar to treatment with O-sialoglycoprotein endopeptidase (OSGE). Neuraminidase treatment of neonatal and adult cells also markedly inhibited the interaction. In a detachment assay marked differences were noted between neonatal and adult cells treated with either 3RB-PSGL-1 or neuraminidase. Such treatments had little effect on adult neutrophils until shear stress exceeded 2.8 dynes/cm2. Treated neonatal neutrophils were exquisitely sensitive to shear stress with a marked decrease in interaction noted at a shear stress as low as 0.6 dynes/cm2. Thus the adhesive mechanisms that remain after treatment with neuraminidase or 3RB-PSGL-1 have a relatively low avidity and function less well in neonatal neutrophils compared to adult neutrophils. We speculate that this may account for the less efficient adhesion of neonatal neutrophils to P-selectin under conditions of flow. J. Leukoc. Biol. 67: 73–80; 2000.

Enterococcus faecalis aggregation substance (AS) mediates efficient bacterium-bacterium contact to facilitate plasmid exchange as part of a bacterial sex pheromone system. We have previously determined that AS promotes direct, opsonin-independent binding of E. faecalis to human neutrophils (PMNs) via complement receptor type 3 and other receptors on the PMN surface. We have now examined the functional consequences of this bacterium-host cell interaction. AS-bearing E. faecalis was phagocytosed and internalized by PMNs, as determined by deconvolution fluorescence microscopy. However, these bacteria were not killed by PMNs, and internalized bacteria excluded propidium iodide, indicating intact bacterial membranes. Resistance to killing occurred despite activation of PMNs, as indicated by an increase in both functional and total surface Mac-1 expression, shedding of l -selectin, and an increase in PMN extracellular superoxide and phagosomal oxidant production. Deconvolution fluorescence microscopy also revealed that phagosomes containing AS-bearing bacteria were markedly larger than phagosomes containing opsonized E. faecalis , suggesting that some modification of phagosomal maturation may be involved in AS-induced resistance to killing. PMN phagosomal pH was significantly higher after ingestion of nonopsonized AS-bearing E. faecalis than after that of opsonized bacteria. The novel ability of AS to promote intracellular survival of E. faecalis inside PMNs suggests that AS may be a virulence factor used by strains of E. faecalis.

Enterococcus faecalis aggregation substance (AS) mediates efficient adhesion between bacteria, thereby facilitating plasmid exchange as an integral part of a bacterial sex pheromone system. We examined the interaction of AS-bearing E. faecalis with human neutrophils (PMNs), an important component of the host defense system. AS promoted a markedly increased opsonin-independent bacterial binding to PMNs. Adhesion was dependent on the expression of the enterococcal Asc10 protein, which contains two Arg-Gly-Asp (RGD) sequences, and addition of exogenous RGD-containing peptides inhibited AS-mediated binding by 66%. AS-mediated adhesion was inhibited by 85% by anti-human complement receptor type 3 (CR3) monoclonal antibodies or by use of PMNs from a patient with leukocyte adhesion deficiency. However, AS-bearing E. faecalis cells were unable to bind to CHO-Mac-1 cells, expressing functionally active CR3, suggesting the potential need for additional PMN surface receptors for bacterial adhesion. Monoclonal antibodies against integrin-associated protein (CD47) and L -selectin, both of which may interact with CR3 and bind to ligands on E. faecalis , also inhibited AS-dependent binding. The non-opsonic binding of E. faecalis to PMNs may play an important role in this organism’s pathogenesis.

Background Recent experimental data suggest that the inflammatory response of the host to verotoxin and/or lipopolysaccharides of Escherichia coli is involved in the pathophysiology of verotoxin-producing E. coli (VTEC) infections. Methods We measured the circulating concentrations of cytokines [TNF-alpha, interleukin (IL)-1-beta, IL-1 receptor antagonist (Ra), IL-6, IL-8, IL-10] and soluble leukocyte adhesion molecules (L-selectin, P-selectin, E-selectin, intracellular cell adhesion molecule-1, vascular cell adhesion molecule-1) by sandwich enzyme-linked immunosorbent assay among (1) normal controls (n = 12), (2) disease controls with hemorrhagic colitis (HC) not associated with VTEC infections (n = 57), (3) patients with uncomplicated HC caused by E. coli O157:H7 (n = 30), and (4) children with hemolytic-uremic syndrome (HUS) (n = 28). Patients with HUS were matched with children who presented an uncomplicated HC caused by E. coli O157:H7 for the time interval elapsed between the onset of HC and that of blood sample collection. Results Concentrations of TNF-alpha and IL-1-beta were undetectable. Children with HUS were characterized by increased amounts of IL-6 and IL-8, lower values of soluble L-selectin as well as increased levels of IL-10 and IL-1Ra. The circulating concentrations of IL-1Ra were higher among children with O157:H7 HC who subsequently developed HUS. Conclusions Increased pro- and antiinflammatory cytokine responses are produced by the host during the development of HUS among children with VTEC infections. Further studies are needed to determine their relative contribution to the pathophysiology of classic HUS.

To further define the neonatal neutrophil's ability to localize to inflamed tissue compared with adult cells, we examined the neonatal neutrophil interactions with P-selectin monolayers under two conditions: (1) attachment under constant shear stress and flow and (2) detachment where cells were allowed to attach in the absence of shear stress and then shear stress is introduced and increased in step-wise increments. Cord blood and adult neutrophils had minimal interactions with unstimulated human umbilical vein endothelial cells (HUVECs) at a constant shear stress of 2 dynes/cm2. There was a marked increase in the number of both neonatal and adult cells interacting (interacting cells = rolling + arresting) with HUVECs after histamine stimulation, although the neonatal value was only 40% of adult (P < .05). Neonatal neutrophils also had significantly decreased interaction with monolayers of Chinese hamster ovary (CHO) cells transfected with human P-selectin (CHO-P-selectin; 60% of adult values, P < .003). Of the interacting cells, there was a lower fraction of neonatal cells that rolled compared with adult cells on both stimulated HUVECs and CHO-P-selectin. That neonatal neutrophil L-selectin contributes to the diminished attachment to P-selectin is supported by the following: (1) Neonatal neutrophils had significantly diminished expression of L-selectin. (2) Anti–L-selectin monoclonal antibody reduced the number of interacting adult neutrophils to the level seen with untreated neonatal neutrophils, but had no effect on neonatal neutrophils. In contrast, L-selectin appeared to play no role in maintaining the interaction of either neonatal or adult neutrophils in the detachment assay. Once attachment occurred, the neonatal neutrophil's interaction with the P-selectin monolayer was dependent on LFA-1 and to other ligands to a lesser degree based on the following: (1) Control neonatal neutrophils had decreased rolling fraction compared with adult neutrophils, although the total number of interacting neutrophils was equal between groups. (2) Anti–LFA-1 treatment resulted in an increase in the rolling fraction of both neonatal and adult neutrophils. However, whereas the number of interacting adult neutrophils remained unchanged, the number of neonatal neutrophils decreased with increased shear stress. We speculate that this increased detachment of neonatal cells is due to differences in neutrophil ligand(s) for P-selectin.

While the clinical disciplines who practice in the pediatric critical care unit are increasing, this chapter focuses primarily on physician career development, because research for the other medical disciplines is currently limited… Nonetheless, many of the career opportunities discussed in this chapter are also available to nurse practitioners and physician assistants. It is important to consider a career in “epochs”, recognizing that career expertise develops over time, and focus may change. Never before have had so many opportunities existed in critical care. It is the skills sets we use as intensivists, which help us develop, not only as clinicians, but as educators, basic scientists, administrators, trialists, implementation scientists, patient safety and quality improvement specialists, and medical informatics officers.

OBJECTIVE To review the findings and discuss the implications of jugular venous bulb oxygenation monitoring in children with severe traumatic brain injury. DESIGN A critical appraisal of Perez et al, Jugular venous oxygen saturation or arteriovenous difference of lactate content and outcome in children with severe traumatic brain injury. FINDINGS Two episodes of jugular venous bulb desaturation and abnormal values of arteriovenous difference in lactate content are associated with poor neurologic outcome in children with severe traumatic brain injury-risk ratio 6.6 (95% confidence interval, 1.5-29.7) and risk ratio 17.6 (95% confidence interval, 2.5-122.5), respectively. This confirms the findings of previously reported adult studies. CONCLUSIONS This study is the first to demonstrate that jugular venous monitoring may aid in predicting the neurologic outcome of children with severe traumatic brain injury. More studies need to be performed (particularly on safety) before adopting jugular venous bulb oxygenation monitoring as a prediction tool or, ultimately, as a therapeutic intervention to help manage and improve outcome for children with severe traumatic brain injury.

Objective:To quantitate ventricular systolic mechanics in septic children.Design:Prospective wall-stress analysis was compared to standard ejection phase indices.Setting:University-based pediatric intensive care unit.Patients:Fifteen children with sepsis (hemodynamically stable, n = 5; in shock, n =

Human neonatal neutrophils manifest decreases in mobility, adherence, and emigration compared with adult neutrophils that may contribute to the increased susceptibility of neonates to infection. In a developmental rabbit model, we show a reduced ability of neutrophils from 1-day-old rabbit pups to emigrate to inflamed peritoneium (3.7 +/- 0.35 x 10(6) neutrophils/mL peritoneal exudate) compared with 14-day- old (8.5 +/- 0.7 x 10(6)/mL) and adult rabbits (9.4 +/- 1.4 x 10(6) mL, P < .05) despite significantly increased blood neutrophil counts. Because the reductions in functional Mac-1 (CD11b/CD18) as well as the amount of surface L-selectin are hypothesized to be primarily responsible for the differences in human neonatal neutrophil mobility, we examined CD11b/CD18 and L-selectin in our model. Using flow cytometric analysis we found that similar to human neonates, neutrophils from 1-day-old rabbit pups had 57% of adult rabbit levels of L-selectin and, in contrast with adults, failed to show significant decreases in L-selectin after chemotactic stimulation. In addition, neutrophils from 1-day-old pups compared with adults showed a significantly diminished capacity to upregulate CD11b/CD18 after chemotactic stimulation in vitro, or after emigration to the inflamed peritoneum. Systemic administration of anti-L-selectin monoclonal antibody (MoAb) resulted in significant reduction in peritoneal neutrophils in adult (47%, P < .05) and 14-day-old rabbits (47%, P < .05), but was without effect in 1-day-old rabbits. Administration of anti-CD18 MoAb resulted in significant reduction in peritoneal neutrophil accumulation in all age groups though less in 1 day and 14 day (58% and 65%, respectively) than in adults (91%, P < .05). Only in the 14-day-old rabbits was there an additive effect of anti-L-selectin and anti-CD18 MoAbs compared with anti-CD18 alone (84% v 65%, P < .05). The findings in this in vivo rabbit model support the hypothesis that the previously described in vitro defects in human neonatal L-selectin and CD11b/CD18 may be major contributors to human neonatal inflammatory deficits.

To determine chronic illness outcomes after admission with multiple organ dysfunction syndrome (MODS) for patients in the pediatric intensive care unit (PICU).We evaluated consecutive PICU admissions from 35 US children's hospitals from January 2004-December 2005 in the virtual PICU Performance System database. We excluded hospitals with10% missing values for MODS variables and patients1 month or18 years of age. MODS was identified by laboratory and vital sign values from day of admission with International Pediatric Sepsis Consensus Conference criteria. Chronic illness was identified by secondary diagnoses, classified by modified Delphi method. We evaluated functional outcomes with pediatric overall performance category and pediatric cerebral performance category scores from PICU admission and discharge.Of 44 693 admissions, 52.1% had a chronic diagnosis. Chronic diagnoses increased MODS at PICU admission (24.6% vs 12.0%, P.001) and mortality rates (3.7% vs 1.9%, P.001). Patients with a chronic diagnosis had similar changes in pediatric overall performance category and pediatric cerebral performance category scores from PICU admission to discharge as previously healthy children. However, outcome in different chronic diagnosis categories was variable.Chronic illness increased MODS incidence at PICU admission and impacted all-cause PICU mortality rates. Although, in aggregate, children who survive return to baseline functional status, this varies by chronic illness category.

The epidemiology and outcomes of multiple organ dysfunction syndrome (MODS) are incompletely characterized in the pediatric population due to small sample size and conflicting diagnoses of organ failure. We sought to describe the epidemiology and outcomes of early MODS in a large clinical database of pediatric intensive care unit (PICU) patients based on consensus definitions of organ failure.Retrospective analysis of a contemporaneously collected clinical PICU database.Virtual Pediatric Intensive Care Unit Performance System database patient admissions from January 2004 to December 2005 for 35 U.S. children's hospitals.: We evaluated 63,285 consecutive PICU admissions from January 2004 to December 2005 in the Virtual Pediatric Intensive Care Unit Performance System database. We excluded patients younger than 1 month or older than 18 years of age, and hospitals with10% missing values for MODS variables. We identified day 1 MODS by International Pediatric Sepsis Consensus Conference criteria with day 1 laboratory and vital sign values. We evaluated functional status using Pediatric Overall Performance Category and Pediatric Cerebral Performance Category scores from PICU admission and discharge.Student's t test, chi-square test, Mann-Whitney rank sum, Kruskal-Wallis, and linear and logistic regression.We analyzed 44,693 admissions from 28 hospitals meeting inclusion criteria. Overall PICU mortality was 2.8%. We identified day 1 MODS in 18.6% of admissions. Patients with day 1 MODS had higher mortality (10.0% vs. 1.2%, p.001), longer PICU length of stay (3.6 vs. 1.3 days, p.001), and larger change from baseline Pediatric Overall Performance Category and Pediatric Cerebral Performance Category scores at time of PICU discharge (p.001). Infants had the highest incidence of day 1 MODS (25.2% vs. 16.5%, p.001) compared with other age groups.Using the largest clinical dataset to date and consensus definitions for organ failure, we found that children with MODS present on day 1 of intensive care unit admission have worse functional outcomes, higher mortality, and longer PICU length of stay than children who do not have MODS on day 1. Infants are disproportionally affected by MODS.

Markedly deficient expression of membrane-activated complex 1 (Mac-1; CD11b/CD18) by polymorphonuclear neutrophils (PMN) of human neonates compared with adults is well documented. To define postnatal maturation of Mac-1 expression of PMN, lysates of PMN from 21 infants, aged 1–14 months, and concurrent adult controls were assayed by ELISA for total cell content of Mac-1 and LFA-1 (CD11a/CD18), and LFA-1 content was within the normal adult range at all ages tested. Mac-1 content was ∼50% of adult levels for infants 1–2 months of age and steadily increased to reach normal adult levels by 11–12 months of age. For a separate group of 25 infants, aged 0.5–11 months, measurement of surface expression of Mac-1 and LFA-1 on activated PMN by immunofluorescence flow cytometry yielded results that were similar to those obtained by ELISA.

Diets high in cholesterol and cholate such as the Paigen diet have been used to study atherogenesis, lithogenesis, and proinflammatory microvascular changes induced by nutritional hypercholesterolemia. Although these diets lead to chronic hepatic inflammation and fibrosis, the early inflammatory changes have been poorly characterized. TLR4, a known receptor for LPS, is also a receptor for a variety of endogenous ligands and has been implicated in atheroma formation. Here, we specifically examined the early inflammatory response of the liver to the atherogenic (ATH) diet and the possible contribution of TLR4. Animals fed the high-cholesterol/cholate diet for 3 weeks developed a significant, predominantly mononuclear leukocyte infiltration in the liver, hepatic steatosis, elevated hepatic expression of MCP-1, RANTES, and MIP-2, and increased serum levels of liver enzymes. In TLR4-deleted animals, there was a 30% attenuation in the serum alanine transaminase levels and a 50% reduction in the leukocyte infiltration with a fourfold reduction in chemokine expression. In contrast, hepatic steatosis did not differ from wild-type controls. TLR2 deletion had no effect on diet-induced hepatitis but increased the amount of steatosis. We conclude that the early inflammatory liver injury but not hepatic lipid loading induced by the ATH diet in mice is mediated in part by TLR4.

Neutrophils have been observed rolling along the luminal surface of endothelium in small venules (Atherton and Born, 1972, 1973; Fiebig et al., 1991; Ley et al., 1989, 1991a). In the early stages of acute inflammation this phenomenon is markedly increased (House and Lipowsky, 1987; Zimmerman and Granger, 1990; Kubes et al., 1990; Hernandez et al., 1987), and the rolling cells frequently stop, change shape, and emigrate into the surrounding tissue. Arfors et al., (1987) initially raised the possibility that the mechanisms accounting for the rolling phenomenon are different from those causing stationary adhesion and emigration. They observed, in a study on the effects of anti-CD 18 monoclonal antibody 60.3 in a rabbit model of inflammation, that the systemic administration of this antibody prevented neutrophils from stopping and transmigrating, but the rolling behavior of these cells was apparently unaffected. Lawrence et al., (1990) used a parallel plate flow chamber in vitro to stimulate some of the forces affecting neutrophil adhesion to endothelial cells, and assessed the ability of isolated neutrophils to adhere while flowing past a confluent monolayer of human umbilical vein endothelial cells (HUVEC). They demonstrated that in this flow system, few neutrophils interacted with the HUVEC monolayer even at wall shear stresses much lower than those predicted to occur in vivo.

• Objective. —To determine the incidence of severe measles-related laryngotracheobronchitis in patients hospitalized during a recent measles epidemic and to evaluate factors associated with severity of airway injury and its management. Design. —Clinical description of patient series. Setting.—Children's hospital and county general hospital, Houston, Tex. Patients. —One hundred twenty-four children (aged 1 month to 19 years) admitted with a diagnosis of measles. Interventions. —None. Measurements/Results. —Twenty-seven patients had significant laryngotracheobronchitis, including 10 who had not received appropriate immunization. Six patients required endotracheal intubation for relief of upper airway obstruction. The median age of patients requiring intubation was 12 months (range, 4 to 24 months). Two patients died of complications of superinfection. Two patients survived but required prolonged intubation. Two patients underwent early diagnostic laryngoscopy and bronchoscopy and required shorter artificial airway maintenance. Conclusions. —Severe laryngotracheobronchitis frequently occurs in patients younger than 2 years hospitalized with measles and may be related to bacterial or viral superinfection. Early diagnostic laryngoscopy and bronchoscopy for injury assessment and possible endotracheal tube exchange are recommended and, in some severe cases, tracheostomy should be considered to shorten artificial airway maintenance and decrease the incidence of airway complications. (AJDC. 1992;146:1040-1043)

Contribution of Mac-1 and LFA-1 to Neonatal PMN Adhesion and Migration under Shear Stress • 1400

The virulence of Group A Streptococcus (GAS) is due to multiple factors including the production of superantigens such as Streptococcus Pyrogenic Exotoxin A (SPEA). Superantigens activate the T-lymphocyte through a non-specific MHC-antigen presenting cell complex of which intercellular adhesion molecule-1 (ICAM-1) is a necessary component. We sought to determine the contribution of ICAM-1 in the host response to SPEA-producing and non-SPEA producing GAS.

Marginating PMNs roll along the post-capillary wall prior to stopping and emigrating. This process is mediated in part by P-SEL on the endothelial cell and its ligand, PSGL-1, and requires the presence of sialyl Lewisx and sulfation of one or more tyrosine in N-terminal sequence. We have previously shown that while P-SEL supports adult PMN (A-PMN) rolling, N-PMNs demonstrate an impairment in their ability to roll, and require CD11a/CD18 to resist detachment to increased shear stress (Ped Res 1996;39:302A). We hypothesize that these findings are in part due to differences in neonatal PSGL-1. Here we investigate N-PMN rolling on a confluent cell line expressing human P-SEL under two conditions: 1)attachment under continuous flow at a wall shear stress of 2 dyn/cm2; 2)detachment with step-wise increases in shear stress (0.6-22 dyn/cm2) in the presence of an anti-CD11a MoAb after a two minute stationary contact between PMNs and monolayer. We developed and purified a polyclonal antibody directed against the N-terminal sequence of PSGL-1 (anti-PSGL Ig) containing the putative sulfation sites. Using flow cytometry we could detect no statistical differences in the amount of PSGL-1 on N-PMNs compared to A-PMNs (173±43 and 210±60, respectively). In the attachment assay under continuous flow, anti-PSGL Ig inhibited the number of rolling N-PMNs (109±33) and A-PMNs (125±94) significantly compared to control Ig (N-PMN: 599±108; A-PMN: 651±57, p

P-SELECTIN SUPPORT OF NEONATAL NEUTROPHIL(PMN) ROLLING IS DIMINISHED UNDER FLOW CONDITIONS: DIFFERENCES IN L-SELECTIN AND P-SELECTIN LIGAND(S). ▴ 1797