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Chronic interstitial lung abnormalities have been described in sickle cell disease (SCD) and attributed to repetitive episode of acute chest syndrome. We report a series of 22 cases of diffuse cystic lung disease in SCD with a case-control study to hunt for mechanism. On pathological analysis of a surgical lung biopsy of the index case, the bronchioles had the appearance of constrictive bronchiolitis. Pulmonary function test results revealed lower forced expiratory flow from 25% to 75% of vital capacity in cases versus controls. These findings suggest a bronchiolar mechanism that was not associated with more acute chest syndrome., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

This study sought to link cardiac phenotypes in homozygous Sickle Cell Disease (SCD) patients with clinical profiles and outcomes using cluster analysis. We analyzed data of 379 patients included in the French Etendard Cohort. A cluster analyses was performed based on echocardiographic variables, and the association between clusters, clinical profiles and outcomes was assessed. Three clusters were identified. Cluster 1 (n = 123) patients had the lowest cardiac output, mild left cardiac cavities remodeling, mild diastolic dysfunction, and higher tricuspid regurgitation velocity (TRV). They were predominantly female and displayed the most altered functional limitation. Cluster 2 (n = 102) patients had the highest cardiac output and the most remodeled cardiac cavities. Diastolic function and TRV were similar to cluster 1. These patients had a higher blood pressure and a severe hemolytic anemia. Cluster 3 (n = 154) patients had mild left cardiac cavities remodeling, normal diastolic function and lowest TRV values. They were younger with the highest hemoglobin value. Right heart catheterization was performed in 94 patients. Cluster 1 (n = 33) included the majority of pre-capillary PH whilst cluster 2 (n = 34) included post-capillary PH. No PH was found in cluster 3 (n = 27). After a follow-up of 11.4 ± 2 years, death occurred in 41 patients (11%). Cluster 2 patients had the worst prognosis with a 19% mortality rate versus 12% in cluster 1 and 5% in cluster 3 (p log-rank = 0.003). Cluster analysis of echocardiography variables identified three hemodynamic and clinical phenotypes among SCD patients, each predicting a different prognosis., (© 2021 Wiley Periodicals LLC.)

Rationale: Precapillary pulmonary hypertension (PH) is a devastating complication of sickle cell disease (SCD). Little is known about the influence of the SCD genotype on PH characteristics., Objectives: To describe clinical phenotypes and outcomes of precapillary PH due to SCD according to disease genotype., Methods: A nationwide multicentre retrospective study including all patients with SCD-related precapillary PH from the French PH Registry was conducted. Clinical characteristics and outcomes according to SCD genotype were analysed., Results: 58 consecutive SCD patients with precapillary PH were identified, of whom 41 had homozygous for haemoglobin S (SS) SCD, three had S-β 0 thalassaemia (S-β 0 thal) and 14 had haemoglobin SC disease (SC). Compared to SC patients, SS/S-β 0 thal patients were characterised by lower 6-min walk distance (p=0.01) and lower pulmonary vascular resistance (p=0.04). Mismatched segmental perfusion defects on lung scintigraphy were detected in 85% of SC patients and 9% of SS/S-β 0 thal patients, respectively, and 50% of SS/S-β 0 thal patients had heterogeneous lung perfusion without segmental defects. After PH diagnosis, 31 patients (53%) received medical therapies approved for pulmonary arterial hypertension, and chronic red blood cell exchange was initiated in 23 patients (40%). Four patients were managed for chronic thromboembolic PH by pulmonary endarterectomy (n=1) or balloon pulmonary angioplasty (n=3). Overall survival was 91%, 80% and 60% at 1, 3 and 5 years, respectively, without influence of genotype on prognosis., Conclusions: Patients with precapillary PH related to SCD have a poor prognosis. Thrombotic lesions appear as a major component of PH related to SCD, more frequently in SC patients., Competing Interests: Conflict of interest: L. Savale reports grants, personal fees and non-financial support from Actelion, MSD, GSK and Bayer, outside the submitted work. Conflict of interest: A. Habibi has nothing to disclose. Conflict of interest: F. Lionnet has nothing to disclose. Conflict of interest: B. Maitre has nothing to disclose. Conflict of interest: V. Cottin reports personal fees for consultancy and lectures, and non-financial support for travel to meetings from Actelion, grants, personal fees for consultancy and lectures, and non-financial support for travel to meetings from Boehringer Ingelheim and Roche, personal fees for consultancy from Bayer/MSD and Galapagos, personal fees for adjudication committee work from Gilead, personal fees for consultancy and lectures from Novartis and Astra Zeneca, grants from Sanofi, and personal fees for data monitoring committee work from Promedior and Celgene, outside the submitted work. Conflict of interest: X. Jais reports grants, personal fees and non-financial support from Actelion, MSD, GSK and Bayer, outside the submitted work. Conflict of interest: A. Chaouat has nothing to disclose. Conflict of interest: E. Artaud-Macari has nothing to disclose. Conflict of interest: M. Canuet reports personal fees for advisory board work from Actelion, non-financial support for travel to meetings from France Oxygene, outside the submitted work. Conflict of interest: G. Prevot has nothing to disclose. Conflict of interest: C. Chantalat-Auger has nothing to disclose. Conflict of interest: D. Montani reports grants and personal fees from Actelion and Bayer, personal fees from GSK, MSD and Pfizer, outside the submitted work. Conflict of interest: O. Sitbon reports grants, personal fees and non-financial support from Actelion Pharmaceuticals and GlaxoSmithKline, grants and personal fees from Bayer HealthCare, grants and non-financial support from Merck, personal fees from Arena Pharmaceuticals, outside the submitted work. Conflict of interest: F. Galacteros has nothing to disclose. Conflict of interest: G. Simonneau reports grants, personal fees and non-financial support from Actelion Pharmaceuticals and GlaxoSmithKline, grants and personal fees from Bayer HealthCare, grants and non-financial support from Merck, personal fees from Arena Pharmaceuticals, outside the submitted work. Conflict of interest: F. Parent has nothing to disclose. Conflict of interest: P. Bartolucci has nothing to disclose. Conflict of interest: M. Humbert has relationships with drug companies including Actelion, Bayer, GSK, Novartis, Pfizer and United Therapeutics. In addition to being investigator in trials involving these companies, relationships include consultancy service and membership of scientific advisory boards., (Copyright ©ERS 2019.)

Nitric oxide (NO) donors may be useful for treating pulmonary hypertension (PH) complicating sickle cell disease (SCD), as endogenous NO is inactivated by hemoglobin released by intravascular hemolysis. Here, we investigated the effects of the new NO donor NCX1443 on PH in transgenic SAD mice, which exhibit mild SCD without severe hemolytic anemia. In SAD and wild-type (WT) mice, the pulmonary pressure response to acute hypoxia was similar and was abolished by 100 mg/kg NCX1443. The level of PH was also similar in SAD and WT mice exposed to chronic hypoxia (9% O2) alone or with SU5416 and was similarly reduced by daily NCX1443 gavage. Compared with WT mice, SAD mice exhibited higher levels of HO-1, endothelial NO synthase, and PDE5 but similar levels of lung cyclic guanosine monophosphate. Cultured pulmonary artery smooth muscle cells from SAD mice grew faster than those from WT mice and had higher PDE5 protein levels. Combining NCX1443 and a PDE5 inhibitor suppressed the growth rate difference between SAD and WT cells and induced a larger reduction in hypoxic PH severity in SAD than in WT mice. By amplifying endogenous protective mechanisms, NCX1443 in combination with PDE5 inhibition may prove useful for treating PH complicating SCD.

Pulmonary artery thrombosis (PAT) is involved in lung vascular dysfunction during acute chest syndrome (ACS) complicating sickle cell disease (SCD). No clinical score is available to identify patients eligible for multi-detector computed tomography (MDCT) angiography during ACS. This retrospective study aimed to develop a risk score for PAT during ACS (PAT-ACS risk score). Patients with SCD were investigated by MDCT during ACS. A logistic regression was performed to determine independent risks factors for PAT and to build the PAT-ACS risk score. A total of 43 episodes (11·9%) of PAT were diagnosed in 361 episodes of ACS. Multivariate analysis identified four risk factors, which were included in the PAT-ACS risk score: a baseline haemoglobin >82 g/l, the lack of a triggering factor for ACS, a platelet count >440 × 10 9 /l and a PaCO 2 <38 mmHg at ACS diagnosis. The area under the receiver operating characteristic curve for the PAT-ACS risk score was 0·74 (95% confidence interval [CI] 0·69-0·79) and differed from that of the revised Geneva score (0·63 (95% CI 0·58-0·69); P = 0·04). The negative predictive value of a PAT-ACS risk score ≥2 was 94%. In conclusion, we propose a simple clinical risk score to identify SCD patients at high risk of PAT during ACS., (© 2017 John Wiley & Sons Ltd.)

Diagnosis of delayed hemolytic transfusion reactions (DHTR), one of the most dreaded complications of transfusion in patients with sickle cell disease (SCD), is challenging and not straightforward. Current diagnostic approaches are complex and not consensual; they are based on assessment of hemoglobin (Hb) drop and enhanced hemolysis, features also seen during classical vaso-occlusive events. In this observational study, we tested the hypothesis that the rate of decline in HbA after an index transfusion is a surrogate marker for the destruction of transfused RBC, which could be used diagnostically. We examined 421 transfusion episodes (in 128 patients of a French referral center for SCD) for which an Hb electrophoresis was obtained within 1 week following an index transfusion and repeated within 2 months (before a subsequent scheduled transfusion or during an acute complication). Chart review found DHTR to be present in 26 cases (6.2%), absent in 389 cases (92.4%), and possible in six cases (1.4%). As expected, DHTR was associated with accelerated hemolysis (increased serum bilirubin and lactic dehydrogenase concentrations) and a decline in total Hb as compared to the early post-transfusion value. However, the decline in HbA concentration appeared more effective in segregating between patients without DHTR and others. We propose a diagnostic nomogram for DHTR based on Hb A as a biologic marker of the survival of transfused RBCs. Am. J. Hematol. 91:1181-1184, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background: Acute chest syndrome (ACS) is the most common cause of death among sickle cell disease (SCD) adult patients. Pulmonary vascular dysfunction (PVD) and acute cor pulmonale (ACP) are common during acute respiratory distress syndrome (ARDS) and their prevalence may be even more important during ARDS related to ACS (ACS-ARDS). The objective of this study was to evaluate the prevalence and prognosis of PVD and ACP during ACS-ARDS., Patients and Methods: This was a retrospective analysis over a 10-year period of patients with moderate-to-severe ARDS. PVD and ACP were assessed by echocardiography. ARDS episodes were assigned to ACS-ARDS or nonACS-ARDS group according to whether the clinical insult was ACS or not, respectively. To evaluate independent factors associated with ACP, significant univariable risk factors were examined using logistic regression and propensity score analyses., Results: A total of 362 patients were analyzed, including 24 ACS-ARDS. PVD and ACP were identified, respectively, in 24 (100%) and 20 (83%) ACS-ARDS patients, as compared with 204 (60%) and 68 (20%) nonACS-ARDS patients (P < 0.0001). The mortality did not differ between ACS-ARDS and nonACS-ARDS patients. Both the crude (odds ratio [OR], 19.9; 95% confidence interval [CI], 6.6-60; P < 0.0001), multivariable adjustment (OR, 27.4; 95% CI, 8.2-91.5; P < 0.001), and propensity-matched (OR, 11.7; 95% CI, 1.2-110.8; P = 0.03) analyses found a significant association between ACS-ARDS and ACP., Conclusions: All SCD patients presenting with moderate-to-severe ARDS as a consequence of ACS experienced PVD and more than 80% of them exhibited ACP. These results suggest a predominant role for PVD in the pathogenesis of severe forms of ACS.

Production of abnormal hemoglobin (HbS) in sickle-cell disease (SCD) results in its polymerization in deoxygenated conditions and in sickled-RBC formation. Dense RBCs (DRBCs), defined as density >1.11 and characterized by increased rigidity are absent in normal AA subjects, but present at percentages that vary of a patient to another remaining stable throughout adulthood for each patient. Polymerized HbS has reduced affinity for oxygen, demonstrated by the rightward shift of the oxygen-dissociation curve, leading to disturbances in oxygen transport. Ninety-two SCD patients' total RBCs were separated into LightDRBC (LRBC) (d < 1.11 g/mL) and DRBC fractions. Venous blood partial oxygen pressure and RBC-fraction-deoxygenation and -reoxygenation Hb-oxygen-equilibrium curves were determined. All patients took a 6-minute walking test (6MWT); 10 had results before and after >6 months on hydroxyurea. 6MWT time with SpO2  < 88% (TSpO2  < 88) assessed the physiological impact of exertion. Elevated mean corpuscular hemoglobin (Hb) concentrations, decreased %HbF, and 2,3-bisphosphoglycerates in DRBCs modulated Hb-oxygen affinity. Deoxygenation and reoxygenation Hb-oxygen equilibrium curves differed between normal Hb AA and SS RBCs and between LRBCs and DRBCs, with rightward shifts confirming HbS-polymerization's role in affinity loss. In bivariate analyses, 50% Hb saturation correlated positively with %DRBCs (P < 0.0001, r(2)  = 0.34) and negatively with %HbF (P < 0.0001, r(2)  = 0.25). The higher the %DRBCs, the longer the TSpO2 88 (P = 0.04). Hydroxyurea was associated with significantly shorter TSpO2  < 88 (P = 0.01). We report that the %DRBCs directly affects SCD patients' SpO2 during exertion; hydroxyurea improves oxygen affinity and lowers the %DRBCs. Am. J. Hematol. 91:1008-1013, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Acute chest syndrome (ACS) is the leading cause of ICU admission in patients with sickle cell disease and is characterized by golden sputum, which is commonly attributed to the presence of bilirubin. Three young consecutive patients with homozygous sickle cell disease were admitted for severe acute respiratory syndrome due to ACS. In all 3 patients, tracheal secretions and bronchoalveolar lavage fluid (BALF) showed a yellowish plasma-like stain. After normalization for the plasma-to-BAL urea ratio, BALF protein and lactate dehydrogenase levels were consistent with an exudative process. BALF bilirubin concentrations were very low, implying that the yellowish stain was not related to bilirubin content. The yellowish coloration of tracheal secretions and BALF observed during ACS appears to be related to an intense exudative process rather than to the presence of bilirubin., (Copyright © 2015 by Daedalus Enterprises.)

Previous reports have suggested a role for weather conditions and air pollution on the variability of sickle cell disease (SCD) severity, but large-scale comprehensive epidemiological studies are lacking. In order to evaluate the influence of air pollution and climatic factors on emergency hospital admissions (EHA) in SCD patients, we conducted an 8-year observational retrospective study in 22 French university hospitals in Paris conurbation, using distributed lag non-linear models, a methodology able to flexibly describe simultaneously non-linear and delayed associations, with a multivariable approach. During the 2922 days of the study, there were 17,710 EHA, with a mean daily number of 6.1 ± 2.8. Most environmental factors were significantly correlated to each other. The risk of EHA was significantly associated with higher values of nitrogen dioxide, atmospheric particulate matters, and daily mean wind speed; and with lower values of carbon monoxide, ozone, sulfur dioxide, daily temperature (minimal, maximal, mean, and range), day-to-day mean temperature change, daily bright sunshine, and occurrence of storm. There was a lag effect for 12 of 15 environmental factors influencing hospitalization rate. Multivariate analysis identified carbon monoxide, day-to-day temperature change, and mean wind speed, along with calendar factors (weekend, summer season, and year) as independent factors associated with EHA. In conclusion, most weather conditions and air pollutants assessed were correlated to each other and influenced the rate of EHA in SCD patients. In multivariate analysis, lower carbon monoxide concentrations, day-to-day mean temperature drop and higher wind speed were associated with increased risk of EHA.

Recent hemodynamic studies performed in large cohorts of adult patients with sickle cell disease have established the prevalence of pulmonary hypertension in this disease about 6 to 10%. Over half of these correspond to postcapillary pulmonary hypertension. Precapilliary arterial pulmonary hypertension seems to be a relatively infrequent complication of the disease. It is characterized by a different hemodynamic profile of idiopathic PAH with lower levels of pulmonary pressures and pulmonary vascular resistance. However, pulmonary vascular disease appears to have a significant impact on the functional status and vital prognosis of patients with sickle cell disease. The predictive value of echocardiography to detect pulmonary hypertension in this population is low (25-32%) when the threshold of tricuspid regurgitation velocity of 2.5m/s is used. At present, no specific treatments for pulmonary arterial hypertension is currently approved for the treatment of PAH associated with sickle cell disease due to lack of data in this specific population., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Rationale: The pathophysiology of acute chest syndrome (ACS) in patients with sickle cell disease is complex, and pulmonary artery thrombosis (PT) may contribute to this complication., Objectives: To evaluate the prevalence of PT during ACS using multidetector computed tomography (MDCT)., Methods: We screened 125 consecutive patients during 144 ACS episodes. One hundred twenty-one MDCTs (in 103 consecutive patients) were included in the study., Measurements and Main Results: Twenty MDCTs were positive for PT, determining a prevalence of 17% (95% confidence interval, 10-23%). Revised Geneva clinical probability score was similar between patients with PT and those without. D-dimer testing was very often positive (95%) during ACS. A precipitating factor for ACS was less frequently found in patients with PT as compared with those without. Patients with PT exhibited significantly higher platelet counts (517 [273-729] vs. 307 [228-412] 10(9)/L, P < 0.01) and lower bilirubin (28 [19-43] vs. 44 [31-71] μmol/L, P < 0.01) levels at the onset of ACS as compared with others. In addition, patients with PT had a higher platelet count peak (537 [345-785] vs. 417 [330-555] 10(9)/L, P = 0.048) and smaller bilirubin peak (36 [18-51] vs. 46 [32-83] μmol/L, P = 0.048)and lactate dehydrogenase peak (357 [320-704] vs. 604 [442-788] IU/L, P = 0.01) during hospital stay as compared with others., Conclusions: PT is not a rare event in the context of ACS and seems more likely in patients with higher platelet counts and lower hemolytic rate during ACS. Patients with sickle cell disease presenting with respiratory symptoms suggestive of ACS may benefit from evaluation for PT.

Background: The prevalence and characteristics of pulmonary hypertension in adults with sickle cell disease have not been clearly established., Methods: In this prospective study, we evaluated 398 outpatients with sickle cell disease (mean age, 34 years) at referral centers in France. All patients underwent Doppler echocardiography, with measurement of tricuspid-valve regurgitant jet velocity. Right heart catheterization was performed in 96 patients in whom pulmonary hypertension was suspected on the basis of a tricuspid regurgitant jet velocity of at least 2.5 m per second. Pulmonary hypertension was defined as a mean pulmonary arterial pressure of at least 25 mm Hg., Results: The prevalence of a tricuspid regurgitant jet velocity of at least 2.5 m per second was 27%. In contrast, the prevalence of pulmonary hypertension as confirmed on catheterization was 6%. The positive predictive value of echocardiography for the detection of pulmonary hypertension was 25%. Among the 24 patients with confirmed pulmonary hypertension, the pulmonary-capillary wedge pressure was 15 mm Hg or less (indicating precapillary pulmonary hypertension) in 11 patients. Patients with confirmed pulmonary hypertension were older and had poorer functional capacity and higher levels of N-terminal pro-brain natriuretic peptide than other patients. In contrast, patients who had a tricuspid regurgitant jet velocity of at least 2.5 m per second without pulmonary hypertension and patients with a tricuspid regurgitant jet velocity of less than 2.5 m per second had similar clinical characteristics., Conclusions: In this study of adults with sickle cell disease, the prevalence of pulmonary hypertension as confirmed on right heart catheterization was 6%. Echocardiographic evaluation alone had a low positive predictive value for pulmonary hypertension. (Funded by the French Ministry of Health and Assistance Publique-Hôpitaux de Paris; ClinicalTrials.gov number, NCT00434902.).

Background: The association between chronic kidney involvement and sickle cell disease (SCD) has been well characterized, but our knowledge on acute kidney injury (AKI) in relation to SCD remains limited., Methods: We retrospectively assessed 254 episodes of vaso-occlusive complication in 161 SCD patients who were admitted to our hospital: these included 174 episodes of painful crisis (PC), 58 episodes of moderate acute chest syndrome (ACS) and 22 episodes of severe ACS., Results: The overall incidence of AKI [defined according to Acute Kidney Injury Network (AKIN) criteria] during vaso-occlusive complications was low (4.3%) but seemed to be related to its severity: 2.3% for PC vs 6.9% for moderate ACS and 13.6% for severe ACS (P = 0.03). This finding led us prospectively to look at specific risk factors for AKI occurrence in SCD patients admitted to our intensive care unit for severe ACS and, in particular, the possible link between AKI and haemodynamic status (transthoracic echocardiography). Among patients with severe ACS, those with AKI displayed significantly greater aminotransferases, bilirubin and lactate dehydrogenase levels than patients without AKI. Echocardiography identified higher systolic pulmonary artery pressure in patients with AKI than in those without, whereas the cardiac index was similar between groups., Conclusions: AKI incidence during vaso-occlusive complications of SCD is relatively low (<5%) and appears to be confined to patients with ACS and pulmonary hypertension. These findings suggest a pathophysiological process involving right ventricular dysfunction and venous congestion.

Purpose: Alveolar hypoxia and hypoxic vasoconstriction lead to trapping of sickle cells within the pulmonary vasculature. Improving alveolar ventilation and oxygenation may improve the outcome of acute chest syndrome (ACS)., Methods: Prospective randomized single-center open study from November 1998 to February 2002 to test whether noninvasive ventilation (NIV) was more effective than oxygen alone in improving oxygenation on day 3 in adults with ACS and to evaluate the effects on pain, transfusion requirements, and length of stay., Results: Seventy-one consecutive ACS episodes in 67 patients were randomly allocated to oxygen (n = 36) or NIV (n = 35) for 3 days in a medical step-down unit. Baseline respiratory rate and pain score were higher in the NIV group. NIV promptly lowered the respiratory rate, raised PaO2, and decreased alveolar-arterial oxygen gradient ((A- a)O2), which remained unchanged with oxygen alone. PaCO2significantly worsened only in the oxygen group. On day 3, the groups did not differ regarding the proportion of episodes with normal PaO2 (35% with NIV and 25% with oxygen; P = 0.5) or A - a). Patient satisfaction and compliance were lower with NIV. No differences were noted in pain relief, transfusions, or length of stay. In the subgroup of patients with severe hypoxemia PaO2

Rationale: Steady-state mild pulmonary hypertension is a risk factor for death in adults with sickle cell disease. Acute pulmonary hypertension has been reported during exercise and vasoocclusive pain crisis in these patients., Objectives: The aim of the present study was to evaluate changes in pulmonary pressures and cardiac biomarkers during severe acute chest syndrome and their associations with mortality., Methods: We prospectively evaluated 70 consecutive adults who received standardized treatment in our intensive care unit for a total of 84 episodes. At admission, cardiac biomarkers were measured. Transthoracic echocardiography was performed for pulmonary hypertension assessment via measurement of tricuspid regurgitant jet velocity and was repeated when possible after resolution., Measurements and Main Results: Tricuspid jet velocity was less than 2.5 m/second in 34 (40%) of the 84 episodes, 2.5 to 2.9 m/second in 19 (23%), and 3 m/second or greater in 31 episodes (37%). Cor pulmonale occurred in 11 (13%) episodes. Tricuspid jet velocity showed significant positive correlations with B-type natriuretic peptide (rho = 0.54, P < 0.01) and cardiac troponin I (rho = 0.42, P < 0.01). Pulmonary pressures increased compared with steady state then decreased after resolution. All five patients who required invasive ventilation and all four patients who died during the immediate hospital course had jet velocity values of 3 m/second or greater. Overall mortality was 12.9% (9 patients) and survival was significantly lower in patients whose jet velocity was 3 m/second or greater during at least one episode, compared with the other patients (P < 0.01)., Conclusions: Pulmonary pressures increase during severe acute chest syndrome, and pulmonary hypertension is associated with cardiac biomarker elevation and a higher risk of death.

Objective: Nitric oxide bioavailability may limit the occurrence or severity of acute vaso-occlusive episodes in patients with sickle cell disease. Because sepsis is frequently involved in the initiation of vaso-occlusive crisis and acute chest syndrome, we designed the present study in transgenic (SAD) sickle cell mice to investigate whether acute infectious peritonitis affects the enzymatic balance (nitric oxide synthases/arginases) that governs lung nitric oxide production., Design: Controlled animal study., Setting: Research laboratory of an academic institution., Subjects: Transgenic Hbbsingle/single SAD1 (SAD) mice and nontransgenic wild-type littermates (C57/Black mice, control group)., Interventions: Cecal ligation and puncture-induced peritonitis., Measurements and Main Results: We found that 24 hrs after peritonitis, control littermate mice showed an increase in inducible and endothelial nitric oxide synthase messenger RNA and proteins, together with an increase in exhaled nitric oxide (shift of the balance toward nitric oxide synthesis). In contrast, SAD mice, which showed elevated inducible and endothelial nitric oxide synthase protein expression at baseline, showed a marked decrease in nitric oxide synthase proteins, lung nitric oxide end-products, and exhaled nitric oxide after peritonitis, reflecting a shift of the enzymatic balance toward inhibition of nitric oxide synthesis. Peritonitis increased messenger RNA levels of arginase I and arginase II in controls and SAD mice but with a greater increase in arginase I in SAD than in control mice. Peritonitis was associated with a higher mortality rate at 24 hrs in SAD mice. Inhalation of nitric oxide (40 ppm in air) abolished the mortality rate induced by acute peritonitis in SAD mice., Conclusions: Acute peritonitis in SAD mice is associated with a defect in lung nitric oxide production and bioavailability that may participate in the acute systemic and lung vaso-occlusive complications of sickle cell disease.

Previous reports have shown that in more than 40% of adults with acute chest syndrome (ACS), fat droplets suggestive of pulmonary fat embolism were present in alveolar macrophages. To determine whether induced sputum (IS) is a reliable test for detecting this embolism, we compared bronchoalveolar lavage and IS results in 20 patients with ACS. We found a correlation between the number of Oil Red O-stained macrophages in sputum and lavage fluid (Spearman's coefficient: rho = 0.657, p < 0.018). Sputum cytology was then studied in another 60 patients who had sickle cell disease with ACS. An elevated percentage of Oil Red O-stained macrophages was found in the sputum of 37/47 patients, but they did not include any of the patients with sickle cell disease but no clinical symptoms. Patients suffering from ACS with Oil Red O-stained macrophages had more extrathoracic concomitant pain than those without (76 vs. 50%, p < 10-8), had more neurologic symptoms (7 vs. 0%, p < 10-8), a lower differential platelet count (-49 +/- 121 vs. +85 +/- 229, p < 0.04), and higher abnormal transaminase values (28 vs. 17%, p < 0.01). We conclude that IS analysis is a safe, noninvasive, and useful test for fat embolism detection in ACS.