HDAC6 selective inhibition of melanoma patient T-cells augments anti-tumor characteristics.

BACKGROUND: Therapies targeting anti-tumor T-cell responses have proven successful in the treatment of a variety of malignancies. However, as most patients still fail to respond, approaches to augment immunotherapeutic efficacy are needed. Here, we investigated the ability of histone deacetylase 6 (HDAC6)-selective inhibitors to decrease immunosuppression and enhance immune function of melanoma patient T-cells in ex vivo cultures. METHODS: T-cells were harvested from peripheral blood or tumor biopsies of metastatic melanoma patients and cultured in the presence of pan-, class-specific or class-selective histone deacetylase (HDAC) inhibitors. Changes in cytokine production were evaluated by Luminex and intracellular flow cytometry staining. Expression of surface markers, transcription factors, protein phosphorylation, and cell viability were assessed by flow cytometry. Changes in chromatin structure were determined by ATAC-seq. RESULTS: T-cell viability was impaired with low doses of pan-HDAC inhibitors but not with specific or selective HDAC inhibitors. The HDAC6-selective inhibitors ACY-1215 (ricolinostat) and ACY-241 (citarinostat) decreased Th2 cytokine production (i.e. IL-4, IL-5, IL-6, IL-10 and IL-13). Expansion of peripheral blood T-cells from melanoma patients in the presence of these inhibitors resulted in downregulation of the Th2 transcription factor GATA3, upregulation of the Th1 transcription factor T-BET, accumulation of central memory phenotype T-cells (CD45RA-CD45RO + CD62L + CCR7+), reduced exhaustion-associated phenotypes (i.e. TIM3 + LAG3 + PD1+ and EOMES+PD1+), and enhanced killing in mixed lymphocyte reactions. The frequency, FOXP3 expression, and suppressive function of T regulatory cells (Tregs) were decreased after exposure to ACY-1215 or ACY-241. Higher frequencies of T-cells expressing CD107a + IFNγ+ and central memory markers were observed in melanoma tumor-infiltrating lymphocytes (TIL), which persisted after drug removal and further expansion. After ACY-1215 treatment, increased chromatin accessibility was observed in regions associated with T-cell effector function and memory phenotypes, while condensed chromatin was found in regions encoding the mTOR downstream molecules AKT, SGK1 and S6K. Decreased phosphorylation of these proteins was observed in ACY-1215 and ACY-241-treated T-cells. AKT- and SGK1-specific inhibition recapitulated the increase in central memory frequency and decrease in IL-4 production, respectively, similar to the observed effects of HDAC6-selective inhibition. CONCLUSIONS: HDAC6-selective inhibitors augmented melanoma patient T-cell immune properties, providing a rationale for translational investigation assessing their potential clinical efficacy.

Targeting histone deacetylase 6 mediates a dual anti-melanoma effect: Enhanced antitumor immunity and impaired cell proliferation.

The median survival for metastatic melanoma is in the realm of 8-16 months and there are few therapies that offer significant improvement in overall survival. One of the recent advances in cancer treatment focuses on epigenetic modifiers to alter the survivability and immunogenicity of cancer cells. Our group and others have previously demonstrated that pan-HDAC inhibitors induce apoptosis, cell cycle arrest and changes in the immunogenicity of melanoma cells. Here we interrogated specific HDACs which may be responsible for this effect. We found that both genetic abrogation and pharmacologic inhibition of HDAC6 decreases in vitro proliferation and induces G1 arrest of melanoma cell lines without inducing apoptosis. Moreover, targeting this molecule led to an important upregulation in the expression of tumor associated antigens and MHC class I, suggesting a potential improvement in the immunogenicity of these cells. Of note, this anti-melanoma activity was operative regardless of mutational status of the cells. These effects translated into a pronounced delay of in vivo melanoma tumor growth which was, at least in part, dependent on intact immunity as evidenced by the restoration of tumor growth after CD4+ and CD8+ depletion. Given our findings, we provide the initial rationale for the further development of selective HDAC6 inhibitors as potential therapeutic anti-melanoma agents.

Efficacy of erythromycin for postpyloric placement of feeding tubes in critically ill children: a randomized, double-blind, placebo controlled study.

BACKGROUND: Erythromycin enhances gastric emptying and has been suggested to facilitate nasoenteric feeding tube placement in adults. Our primary objective was to evaluate the effect of erythromycin on the transpyloric passage of feeding tubes in critically ill children, and second, to evaluate the effect of erythromycin on the distal migration of duodenal feeding tubes. METHODS: Seventy-four children were randomly assigned to receive erythromycin lactobionate (10 mg/kg) IV or equal volume of saline placebo 60 minutes before passage of a flexible weighted tip feeding tube. Abdominal radiographs were obtained 4 hours later to assess tube placement. If the tube was proximal to the third part of the duodenum, two additional doses of erythromycin/placebo were administered 6 hours apart. Those receiving additional doses had repeat radiographs 14 to 18 hours after tube placement. RESULTS: The number of postpyloric feeding tubes was similar in the erythromycin and placebo treated groups 4 hours after tube insertion (23/37 vs 27/37, p = .5). Of those with prepyloric tubes at 4 hours, none in the erythromycin group and 3 in the placebo group had the tube migrate to the postpyloric position by 14 to 18 hours (p < .05). Of those with postpyloric tubes proximal to the third part of the duodenum at 4 hours, additional doses of erythromycin did not cause more tubes to advance further into the intestine than did placebo (p = .6). CONCLUSIONS: Erythromycin does not facilitate transpyloric passage of feeding tubes in critically ill children. The distal migration of duodenal tubes further into the small bowel is also not enhanced by erythromycin.

Heat stress is associated with decreased lactic acidemia in rat sepsis.

BACKGROUND: Elevated plasma lactate has been shown to correlate with mortality in patients with septic shock. Heat stress prior to sepsis has resulted in reduction in acute lung injury and mortality. We investigated whether heat stress resulted in decreased plasma lactate concentration and protected the lung by decreasing the inflammatory response to sepsis. RESULTS: Plasma lactate concentration was elevated in septic rats without prior heat stress. Lactic acid levels were significantly lower in heat-treated septic rats (P < 0.05) and were not significantly different when compared with control rats. Septic rats with or without heat pretreatment had significantly higher myeloperoxidase activity in the lung than did control groups. Heat pretreatment did not prevent neutrophil infiltration or inflammatory mediator production in the lung. CONCLUSION: Prior heat stress ameliorates lactic acidemia in rat sepsis. Heat stress did not attenuate the pulmonary inflammatory process. The mechanism of heat-induced protection from lactic acidemia in sepsis needs to be further explored.

Indicators of postpyloric feeding tube placement in children.

OBJECTIVE: To determine the validity of five indicators (color, pH, and concentrations of bilirubin, pepsin, and trypsin in aspirated gastrointestinal secretions) in predicting postpyloric placement of feeding tubes in critically ill children. DESIGN: Prospective, observational study. SETTING: University teaching hospital. PATIENTS: A total of 96 gastrointestinal aspirates were obtained from 53 children requiring placement of a nasoenteric feeding tube. INTERVENTIONS: Feeding tubes were aspirated by applying suction with a 20-mL syringe. Repeat aspirates from the same patient were obtained on different days. All aspirations were performed within 30 mins of obtaining a radiograph to assess tube position. MEASUREMENTS AND MAIN RESULTS: Aspirates were inspected visually for color. pH and bilirubin concentrations were determined at the bedside by using reagent strips. Pepsin and trypsin concentrations were measured spectrophotometrically in a research laboratory. The sensitivity, specificity, predictive values, and efficiency for each indicator and their 95% confidence intervals were determined based on the position of the feeding tube on the radiograph. Aspirate pH > or =6 had the lowest positive predictive value (76%, range 67% to 85%) but high negative predictive value (94%, range 89% to 99%) for determining postpyloric positioning of the feeding tube. Bilirubin concentration > or =5 mg/dL (> or =86 micromol/L) had the highest positive predictive value (96%, range 91% to 100%) and lowest negative predictive value (88%, range 81% to 95%). Overall efficiency was best for the appearance of a clear yellow aspirate color (93%, range 88% to 98%), pepsin concentration < or =20 microg/mL (94%, range 89% to 99%), and trypsin concentration > or =50 microg/mL (94%, range 89% to 99%). CONCLUSIONS: Simple bedside assessment of gastrointestinal aspirate color, pH, and bilirubin concentration is useful for predicting feeding tube position. Use of these tests may reduce the number of radiographic studies needed to confirm postpyloric positioning. Laboratory-determined pepsin and trypsin concentrations predict tube position with a high degree of accuracy. Development of simple and inexpensive bedside tests for the detection of gastrointestinal enzymes may be useful.

The effect of heat on cytokine production in rat endotoxemia.

OBJECTIVE: To determine whether heat stress protects the endotoxemic rat by up-regulation of the counterinflammatory cytokine interleukin (IL)-10, thereby attenuating the inflammatory response. DESIGN: A total of 16 rats were assigned to either the heat stress group (n = 8) or the control group (n = 8). The heat stress group was warmed to a temperature of >42 degrees C (107.6 degrees F) rectally for 10-15 mins; 20 hrs later, all rats were intubated, paralyzed, and ventilated. After jugular venous and arterial catheterization, endotoxin was given intravenously. Arterial blood was removed at 0, 2, 4, and 5 hrs for blood gases, tumor necrosis factor (TNF)-alpha, nitric oxide metabolites (NO), IL-10, and macrophage inflammatory protein (MIP)-2. The alveolar macrophages were removed, counted, and then incubated for 24 hrs. The supernatant was analyzed for TNF-alpha, NO, IL-10, and MIP-2. SETTING: University research laboratory. SUBJECTS: Male Sprague-Dawley rats (n = 16). INTERVENTIONS: Administration of heat before endotoxin infusion. MEASUREMENTS AND MAIN RESULTS: Alveolar-arterial oxygen gradient was lower in the heat stress group at 4 and 5 hrs after endotoxemia. Plasma and alveolar macrophage supernatant concentrations of TNF-alpha, NO, and IL-10 were not affected by heat. Plasma and alveolar macrophage supernatant MIP-2 concentrations were higher in endotoxemic rats receiving heat pretreatment compared with controls. CONCLUSIONS: Our study demonstrates that heat leads to pulmonary protection of short duration in severe endotoxemia. This protection was not mediated by plasma TNF-alpha, IL-10, or NO. Contrary to our hypothesis, pretreatment with heat increased rather than decreased the plasma MIP-2 concentration and alveolar macrophage production of MIP-2 in endotoxemia. The mechanism of heat-conferred pulmonary protection in endotoxemia remains unclear. Alveolar macrophages do not produce IL-10 in endotoxemia. The increased MIP-2 production by heated alveolar macrophages was not attributable to alterations in production of either TNF-alpha or IL-10. The significance of increased MIP-2 by endotoxin-exposed alveolar macrophages in heated rats is unknown.

Anesthetic aspects of laparoscopic and open adrenalectomy for pheochromocytoma.

OBJECTIVES: To compare the anesthetic aspects and intraoperative hemodynamic data and immediate postoperative outcomes in patients whose pheochromocytoma resection was performed either laparoscopically or by traditional open surgery. METHODS: Fourteen consecutive patients who underwent laparoscopic procedures (a single surgeon) were compared with 20 patients who underwent open surgery. The patients' records were reviewed for demographic information, preoperative medical history and therapy, intraoperative hemodynamic data, fluid balance, and immediate postoperative course. RESULTS: No differences between the highest intraoperative blood pressures and number of hypertensive episodes between the two groups were found. However, in laparoscopic patients, the intraoperative hypotension was less severe (mean lowest blood pressure 98/57 mm Hg versus 88/50 mm Hg, P = 0.05), and the hypotensive episodes were less frequent (median 0 versus 2, P = 0.005) and required fewer interventions with vasopressors (P = 0.02). Extreme high and extreme low heart rates did not differ between the two groups. The estimated blood loss was lower in the laparoscopic group (P = 0.0001), but the total intraoperative fluid requirement and operative times were similar in the two groups. Patients in the laparoscopic group resumed walking earlier (median 1.5 versus 4 days, P = 0.002) and resumed oral food intake sooner (median 1 versus 3.5 days, P = 0.0001). The median duration of hospitalization in patients who underwent laparoscopic and open adrenalectomy was 3 and 7.5 days, respectively (P = 0.001). CONCLUSIONS: Intraoperative hemodynamic values during laparoscopic adrenalectomy for pheochromocytoma were comparable to those of traditional open surgery, but the patients who underwent the laparoscopic procedure had a faster postoperative recovery.

Expression of stress proteins HSP 72 & HSP 32 in response to endotoxemia.

Pretreatment with heat decreases mortality and acute lung injury in the rat septic shock model, presumably by the production of heat shock proteins (HSP). However, endotoxin, a severe cell stresser, has not been shown to induce HSP 70. We investigated the effects of severe endotoxemia on the expression of specific protective stress proteins, including HSP 72 (inducible HSP 70), HSP 32 (heme oxygenase-1), and HSP 90. Fifteen rats received intravenously either 3 mg/kg of endotoxin (E. coli O127:B8 lipopolysaccharide, LPS) (n=9) or saline (n=6). Two hr later the spleen was removed and splenocytes were separated into three groups and analyzed for specific HSP by Western blot. In Group 1, both endotoxin-treated and saline-treated splenocytes were incubated for 3 hr at 37 degrees C. In Group 2, the splenocytes were washed twice, then heat shocked for 30 min at 42 degrees C and subsequently incubated for 2.5 hr at 37 degrees C. In Group 3, splenocytes were washed twice, then incubated for 3.0 hr at 37 degrees C. HSP 90 & HSP 70c (constitutive) were present in all groups. Consistent with observations by others, HSP 72 was not induced in Group 1. HSP 72 was induced in both the saline-treated and endotoxin-treated splenocytes after heating (Group 2). However, in the absence of heat stress, HSP 72 was present in endotoxin-treated but not in saline-treated splenocytes after incubation (Group 3). Conversely, HSP 32, while present in Group 1 splenocytes, was not detected in the endotoxin-treated splenocytes of Group 2 and Group 3, but was present in the saline-treated cells. In conclusion, endotoxemic shock results in induction of HSP 72 and depletion of HSP 32, but only after the cells have been washed and further incubated.

End-of-life decision-making and satisfaction with care: parental perspectives.

OBJECTIVES: To evaluate parents' perceptions of the process by which decisions are made to limit or withdraw life support from critically ill children, and to evaluate parents' perceptions of their child's death in the pediatric intensive care unit (ICU) and their satisfaction with the care provided. DESIGN: Survey. SETTING: University teaching hospital. PARTICIPANTS: Seventy-eight parents who experienced the death of a child in the ICU between January 1, 1995 and June 30, 1998. INTERVENTIONS: Structured telephone interviews. MEASUREMENTS AND MAIN RESULTS: Forty-one parents recalled discussing the limitation or withdrawal of life support from their child with a physician. Of these, 31 (76%) felt they had just the right amount of authority to make decisions for their child, 8 (20%) felt they had too little, and 1 (2%) felt they had too much. Those satisfied with their decision-making authority had more trust in their physician than those who were dissatisfied (5 vs. 1, p <.001 by Mann-Whitney U test, where 1 = no trust and 5 = complete trust). Factors identified by parents as being extremely important in the decision-making process included physician recommendations, diagnosis, expected neurologic recovery, and degree of pain and suffering. A total of 51 parents were with their child at the time of death. Although none regretted being present, 17 parents who were not present later wished they had been (p <.001, Fisher's exact test). The quality of care provided to parents by the ICU staff was graded (1 = poor; 5 = excellent). Eleven parents (14%) scored quality of care

Effects of insulin and metformin on glucose metabolism in rat vascular smooth muscle.

Glucose metabolism in vascular smooth muscle cells (VSMCs) is characterized by substantial lactate production even in fully oxygenated conditions. Insulin and metformin, an insulin-sensitizing agent, have direct effects on the vascular tissue metabolism. We investigated whether insulin or metformin can induce a switch in VSMC glucose metabolism from lactate production to pyruvate oxidation, by measuring lactate oxidation as determined by the conversion of [1-14C]-D,L-lactate to [1-14C]-pyruvate and subsequent oxidation to acetyl coenzyme A and 14CO2 by pyruvate dehydrogenase (PDH). Lactate oxidation was measured in control rat aortic cultured VSMCs incubated for 30 minutes in media with and without additional glucose compared with VSMCs cultured in the presence of insulin or metformin. The addition of glucose to VSMCs decreased lactate oxidation (4.6+/-1.7 v 9.6+/-2.4 pmol/cell/min, P < .001). In the absence of additional glucose, metformin decreased lactate oxidation in VSMCs compared with controls (4.9+/-1.4 v 9.6+/-2.4 pmol/cell/min, P < .01). Metformin in the presence of glucose caused the greatest decline in lactate oxidation (2.5+/-0.4 pmol/cell/min, P < .001). In contrast to the effects of metformin, insulin increased lactate oxidation both with (12.9+/-1.5 pmol/cell/min, P < .001) and without (17.9+/-4.4, P < .01) additional glucose. This suggests that insulin facilitates VSMC utilization of lactate as a source of pyruvate and energy production even during noncontractile periods.

Expression of MXI1, a Myc antagonist, is regulated by Sp1 and AP2.

MXI1, a member of the MAD family of Myc antagonists, encodes a transcription factor whose expression must be tightly regulated to maintain normal cell growth and differentiation. To more closely investigate the transcriptional regulation of the human MXI1 gene, we have cloned and characterized the MXI1 promoter. After clarification of the 5'- and 3'-untranslated regions of the cDNA (indicating that the true length of the MXI1 transcript is 2643 base pairs), we identified two transcription initiation sites. We subsequently isolated the MXI1 promoter, which is GC-rich and lacks a TATA box. Although it contains at least six potential initiator sequences, functional studies indicate the proximal two initiator sequences in combination with nearby Sp1 and MED-1 sites together account for virtually all promoter activity. We also demonstrate that MXI1 promoter activity is repressed by high levels of AP2. These studies provide further insight into the complex regulatory mechanisms governing MXI1 gene expression and its role in cellular differentiation and tumor suppression.

Ibuprofen attenuates cardiopulmonary dysfunction by modifying vascular tone in endotoxemia.

Ibuprofen, a cyclooxygenase inhibitor, improves pulmonary and cardiovascular injury in endotoxemia. We studied the mechanism of the beneficial effects of ibuprofen in relation to production of inflammatory mediators which influence vascular tone in endotoxemia. Rats were randomly assigned to one of three groups: (1) control, (2) endotoxemia alone; and (3) ibuprofen pretreatment and endotoxemia. Plasma and lung lavage concentrations of tumor necrosis factor, thromboxane B2 (TXB2), leukotriene (LT) C4,D4,E4 and nitric oxide (NO) were determined over a 2 h period. Pretreatment with ibuprofen resulted in increased survival, and attenuation of pulmonary and cardiovascular dysfunction when compared to the rats receiving endotoxin alone. The marked elevation in plasma TXB2 concentration in endotoxemic rats was prevented by pretreatment with ibuprofen. Similarly, pretreatment with ibuprofen prevented the decrease in lung lavage NO levels in endotoxemic rats. The improved survival and cardiopulmonary protection in endotoxemic rats pretreated with ibuprofen appears to be related to decreased thromboxane production and preservation of endothelial production of nitric oxide.

Syndrome of inappropriate antidiuretic hormone secretion in children following spinal fusion.

OBJECTIVES: a) To determine if antidiuretic hormone (ADH) is elevated in patients undergoing spinal fusion, especially in those who have clinical evidence of syndrome of inappropriate antidiuretic hormone (SIADH); b) to evaluate the relationship between ADH secretion and the secretion of atrial natriuretic peptide (ANP). SETTING: Tertiary care pediatric intensive care unit (ICU) in a university hospital. DESIGN: A prospective cross-sectional, observational study with factorial design. PATIENTS: Thirty patients > or = 10 yrs of age undergoing spinal fusion admitted to the ICU for postoperative care. INTERVENTIONS: Patients underwent anterior, posterior, or both anterior/posterior spinal fusion. Blood was collected for serial measurements of ADH, ANP and serum electrolyte levels. Heart rate, blood pressure and central venous pressure were measured. MEASUREMENTS AND MAIN RESULTS: Thirty children were studied. Nineteen had idiopathic scoliosis, nine had neuromuscular scoliosis, one had Marfan's disease, and one had congenital scoliosis. Ten (33%) children met clinical criteria of SIADH. There was no difference in duration of surgery, blood loss, volume of iv fluid administration pre- and intraoperatively, or type of scoliosis between those who developed SIADH and those who did not. Hemodynamic variables were similar in both groups. ADH levels increased in both groups immediately postoperatively and at 6 hrs after surgery, but were much more elevated in those patients with SIADH. Patients with SIADH also had significantly higher ADH levels preoperatively. In relation to serum osmolality, ADH was considerably higher in those with SIADH compared with those who did not. Although ANP values tended to be higher in the group with SIADH, this did not reach statistical significance. CONCLUSION: SIADH occurs in a subset of children who undergo spinal fusion. The diagnosis of SIADH can be made easily using clinical parameters which are well-defined. In the face of SIADH, continued volume expansion may be harmful, and should therefore be avoided.

Anti-s antibody-associated delayed hemolytic transfusion reaction in patients with sickle cell anemia.

PURPOSE: Signs and symptoms of delayed hemolytic transfusion reaction (DHTR) may resemble those of vaso-occlusive crises in patients with sickle cell anemia (SCA). The diagnosis of DHTR therefore presents a challenge to the clinician when treating such patients. The current study describes a patient with SCA and DHTR secondary to red cell anti-s antibody, manifesting as painful extremeties, severe hemolytic anemia, and acute oliguric renal failure. PATIENTS AND METHODS: A 17-year-old patient with homozygous hemoglobin S presented 8 days after partial exchange transfusions with severe anemia and signs and symptoms resembling vaso-occlusive crisis. Clinical course was complicated by intravascular hemolysis and acute renal failure. RESULTS: Anti-s antibody was detected in the eluate. Diagnosis of DHTR was made. Treatment included single volume whole blood exchange transfusion and continuous veno-venous hemofiltration with dialysis. CONCLUSIONS: The possibility of DHTR should be considered in a patient with SCA with hemolytic anemia. Acute renal failure is a rare complication of anti-s antibody-associated DHTR. Such reactions can be successfully managed with exchange transfusion and continuous hemofiltration with dialysis.

Altered T cell cytokine production following mechanical trauma.

BACKGROUND: Cell mediated immunity is suppressed following traumatic injury. The Objective is to determine whether there is a shift from T helper type 1 (TH1) to TH2 cell cytokine production following mechanical trauma in a rat model. METHODS: Male Sprague-Dawley rats were anesthetized and subjected to bilateral femur fractures or sham injury. Spleens were removed 3 days later. T cell proliferation and cytokine production were stimulated by culturing spleen cells with the T cell mitogen concanavalin A (con A). Interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-10 and IL-4 concentrations were measured in spleen cell supernatants using enzyme linked immunosorbent assays. RESULTS: Con A-induced spleen cell proliferation was decreased in traumatized rats compared to controls (p < 0.05). Spleen cell supernatant concentrations of the TH1 cytokines IL-2 and IFN-gamma were decreased in the trauma group (p < 0.05). Supernatant concentrations of the TH2 cytokine IL-10 were also decreased in traumatized rats (p < 0.01). The IL-4 concentrations were below the detection limit (< 15 pg/mL) in all cell supernatants. CONCLUSIONS: Mechanical tissue injury leads to generalized suppression of T helper cell cytokine production rather than a shift from TH1 to TH2 cell activity. Post-trauma cellular immunosuppression is not mediated via excess IL-10 production by TH2 cells.

Macrophage inflammatory protein-2 predicts acute lung injury in endotoxemia.

BACKGROUND: Proinflammatory mediators that include tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-2 (MIP-2) and anti-inflammatory mediators such as interleukin-10 (IL-10) modulate the immune response to endotoxemia. IL-10 downregulates the production of TNF-alpha and MIP-2. Acute lung injury may occur secondary to neutrophil chemotaxis mediated by chemokine MIP-2. We studied the temporal relationship of TNF-alpha, MIP-2, and IL-10 in rat endotoxemia and correlation of MIP-2 concentrations with acute lung injury. METHODS: Ten ventilated rats were randomized to receive an intravenous infusion of 2 mg/kg Escherichia coli lipopolysaccharide (n = 6) or saline placebo (n = 4). Blood pressure was continuously monitored and arterial blood was obtained for lactate, blood gas, TNF-alpha, IL-10, and MIP-2 measurements at baseline, 2, 4, and 5.5 hours after LPS or saline infusion. RESULTS: Endotoxemia resulted in hypotension, lactic acidemia, and increased alveolar-arterial oxygen gradient (A-a O2 gradient) compared with the placebo group. TNF-alpha, MIP-2, and IL-10 levels were increased 2 hours after endotoxemia. Subsequently, TNF-alpha levels declined while IL-10 and MIP-2 levels remained elevated. Control rats had no significant increase in cytokine production at any time point. MIP-2 concentrations correlated with A-a O2 gradient, an indicator of lung injury (r = 0.56, p < 0.001). CONCLUSIONS: MIP-2, possibly released by TNF-alpha stimulation of macrophages, is associated with acute lung injury possibly by inducing neutrophil chemotaxis. IL-10 may exert its counter-inflammatory response by inhibiting the release of TNF-alpha in endotoxemia.

Outcome of children with carbon monoxide poisoning treated with normobaric oxygen.

OBJECTIVE: To evaluate the clinical characteristics and neurologic outcome of children with carbon monoxide poisoning treated with normobaric oxygen therapy. METHODS: We reviewed the medical records of all children with a diagnosis of carbon monoxide exposure admitted during a 10-year period. Exposures were categorized as (1) severely toxic, carboxyhemoglobin level >25%; (2) toxic, carboxyhemoglobin level 10.1 to 25%; (3) suspected toxic, carboxyhemoglobin level < or = 10% with acute neurologic manifestations; or (4) nontoxic, carboxyhemoglobin < or = 10% without acute neurologic manifestations. RESULTS: One hundred six patients (median age, 3.5 years; range, 0.1-14.9 years) were identified, 37 with severe toxic, 37 with toxic, 13 with suspected toxic, and 19 with nontoxic exposures. The most common presenting signs or symptoms included altered level of consciousness, metabolic acidosis, tachycardia, and hypertension. All patients received normobaric oxygen for 5.5 hours (range, 0.6-44 hours). Carboxyhemoglobin levels decreased to less than 3% in 3.6 hours (range, 0-15.5 hours). Fifteen patients died, three from massive burn injury, eight from hypoxic-ischemic encephalopathy after cardiopulmonary arrest at presentation, and four from late complications of burn injury. Seven survivors did not recover their premorbid neurologic state, four of whom had respiratory arrest when rescued. Two patients had initial neurologic recovery followed by transient deterioration at 4 and 14 days after exposure. One patient developed seizures and was found to have bilateral occipital lobe infarctions 51 days after exposure. CONCLUSION: Acute neurologic manifestations after carbon monoxide exposure are common in children. These resolve rapidly with normobaric oxygen, however. Persistent sequelae are primarily related to asphyxia. Delayed neurologic syndromes are uncommon in children treated with normobaric oxygen.