Study protocol of OmegaROP-2 prospective study: expression of placental fatty acid receptors in preterm newborns with retinopathy of prematurity.

BACKGROUND: Incomplete vascularization of the retina in preterm infants carries a risk of retinopathy of prematurity (ROP). Progress in neonatal resuscitation in developing countries has led to the survival of an increasing number of premature infants, resulting in an increased rate of ROP and consequently in visual disability. Strategies to reduce ROP involve optimizing oxygen saturation, nutrition, and normalizing factors such as insulin-like growth factor 1 and n-3 long-chain polyunsaturated fatty acids (LC-PUFA). Our previous study, OmegaROP, showed that there is an accumulation or retention of docosahexaenoic acid (DHA) in mothers of infants developing ROP, suggesting abnormalities in the LC-PUFA placental transfer via fatty acid transporting proteins. The present study aims to better understand the LC-PUFA transport dysfunction in the fetoplacental unit during pregnancy and to find a novel target for the prevention of ROP development. METHODS: The study protocol is designed to evaluate the correlation between the expression level of placental fatty acid receptors and ROP occurrence. This ongoing study will include 100 mother-infant dyads: mother-infant dyads born before 29 weeks of gestational age (GA) and mother-infant dyads with full-term pregnancies. Recruitment is planned over a period of 46 months. Maternal and cord blood samples as well as placental tissue samples will be taken following delivery. ROP screening will be performed using wide-field camera imaging according to the International Classification of ROP consensus statement. DISCUSSION: The results of this study will have a tangible impact on public health. Indeed, if we show a correlation between the expression level of placental omega-3 receptors and the occurrence of ROP, it would be an essential step in discovering novel pathophysiological mechanisms involved in this retinopathy. TRIAL REGISTRATION: NCT04819893.

Detecting Hospital Outliers in Post-Pancreatectomy Care Using Funnel Plots from 2009-2018 Based on Nationwide Medico-Administrative Data.

OBJECTIVES: Our objective was to identify hospitals with unusual mortality rates for major pancreatectomies over a period of ten years using 30-day mortality data from the French national database. METHODS: Data for all patients who underwent pancreatectomy were extracted from the national medico-economic database (Programme de Médicalisation des Systèmes d'Information). To identify quality outliers for each hospital, the observed-to-expected 30-day mortality rates were used as a quality indicator. RESULTS: A total of 19 494 patients underwent a major pancreatectomy in France between January 2009 and December 2018. The overall 30-day mortality rate was 4.8% (n = 944). For the 2009-2014 period, the funnel plot showed that 10 of the 176 hospitals lie outside the central 95% region and 7 lie outside the central 99.8% region. For the 2015-2018 period, out of 176 hospitals, 6 lie outside the central 95% region and 2 lie outside the central 99.8% region. The change in standardized mortality ratios between 2009-2014 and 2015-2018 testing for differences from the overall change, they were there 4 hospitals lie outside the central 95% region and 0 lie outside the central 99.8% region. CONCLUSION: Over time, the improvement in hospital quality was weak. This study suggests that there is a pressing need to reorganize the supply of care for pancreatic surgery in France.

Self-management of immunomodulatory drug treatment in multiple myeloma patients.

OBJECTIVE: Immunomodulatory drugs (IMIDs: thalidomide, lenalidomide and pomalidomide) are widely used in patients with multiple myeloma (MM). The aim of our study was to validate a questionnaire to evaluate the self-capacity of MM patients to manage IMID treatment including side effects. METHODS: We used a method adapted from the recommendations of the European Organisation for Research and Treatment of Cancer (EORTC) to validate a French questionnaire for patients with MM treated with IMIDs. RESULTS: The face validity was evaluated in 15 patients and the construct validity in 56 patients. For discriminant validity, two groups were constituted by gender and depending on whether they had a previous IMID treatment. The median questionnaire score was 11.33/16 (IQR 9.75-12.08) with a minimum of 5.2 and a maximum of 14.75. For discriminant validity, a statistically significant difference was observed for patient capacity to contact healthcare professionals in specific situations and drug intake in case of swallowing disorder. Convergent validity showed an acceptable reliability for the scores of the different questions. CONCLUSION: The questionnaire has shown to be a valid tool for the assessment of the adherence and side-effect management skills for MM patients with IMID treatment.

Glucagon-like peptide-1 is associated with poor clinical outcome, lipopolysaccharide translocation and inflammation in patients undergoing cardiac surgery with cardiopulmonary bypass.

INTRODUCTION: Cardiac surgery with cardiopulmonary bypass (CPB) is associated with gut barrier dysfunction. Gut barrier dysfunction might be estimated non-invasively by lipopolysaccharide (LPS) plasma concentration. Glucagon-like peptide-1 (GLP-1) is a gut secreted hormone that is a potential marker of mucosal integrity. Our objective was to evaluate GLP-1 as a peri-operative marker of gut barrier dysfunction in patients undergoing cardiac surgery with CPB. METHODS: GLP-1, intestinal fatty acid binding protein (I-FABP) and lipopolysaccharide were assayed: at induction, after CPB and 24 h after admission in the intensive care unit. The primary end-point was peri-operative lipopolysaccharide concentration (LPS concentration at those 3 time points). RESULTS: Seventy-two patients were included in the present analysis. The highest measured post-operative GLP-1 concentration was in the sample taken 24 h after admission to intensive care, which was associated with peri-operative lipopolysaccharide plasma concentration. Patients who had the highest GLP-1 concentrations at 24 h experienced more severe inflammation and worse clinical outcomes. CONCLUSION: Our study supports that GLP-1 is not only a hormone of glucose metabolism but is also secreted when gut barrier is impaired in cardiac surgery with CPB. The GLP-1 levels measured 24 h after admission to the intensive care unit were associated with LPS concentration, inflammation and clinical outcomes.

Monitoring of noninvasive ventilation: comparative analysis of different strategies.

BACKGROUND: Noninvasive ventilation (NIV) represents an effective treatment for chronic respiratory failure. However, empirically determined NIV settings may not achieve optimal ventilatory support. Therefore, the efficacy of NIV should be systematically monitored. The minimal recommended monitoring strategy includes clinical assessment, arterial blood gases (ABG) and nocturnal transcutaneous pulsed oxygen saturation (SpO2). Polysomnography is a theoretical gold standard but is not routinely available in many centers. Simple tools such as transcutaneous capnography (TcPCO2) or ventilator built-in software provide reliable informations but their role in NIV monitoring has yet to be defined. The aim of our work was to compare the accuracy of different combinations of tests to assess NIV efficacy. METHODS: This retrospective comparative study evaluated the efficacy of NIV in consecutive patients through four strategies (A, B, C and D) using four different tools in various combinations. These tools included morning ABG, nocturnal SpO2, TcPCO2 and data provided by built-in software via a dedicated module. Strategy A (ABG + nocturnal SpO2), B (nocturnal SpO2 + TcPCO2) and C (TcPCO2 + builtin software) were compared to strategy D, which combined all four tools (NIV was appropriate if all four tools were normal). RESULTS: NIV was appropriate in only 29 of the 100 included patients. Strategy A considered 53 patients as appropriately ventilated. Strategy B considered 48 patients as appropriately ventilated. Strategy C misclassified only 6 patients with daytime hypercapnia. CONCLUSION: Monitoring ABG and nocturnal SpO2 is not enough to assess NIV efficacy. Combining data from ventilator built-in software and TcPCO2 seems to represent the best strategy to detect poor NIV efficacy. Trial registration Institutional Review Board of the Société de Pneumologie de Langue Française (CEPRO 2016 Georges).

Carriage of a Single Strain of Nontoxigenic Corynebacterium diphtheriae bv. Belfanti (Corynebacterium belfantii) in Four Patients with Cystic Fibrosis.

Cystic fibrosis (CF) patients are commonly colonized by bacterial pathogens, which can induce persistent lung inflammation and may contribute to clinical deterioration. Colonization of CF patients and cross-transmission by Corynebacterium diphtheriae have not been reported so far. The aim of this article was to investigate the possibility of a cross-transmission of C. diphtheriae biovar Belfanti between four patients of a CF center. C. diphtheriae biovar Belfanti (now formally called C. belfantii) isolates were collected from four patients in a single CF care center over a period of 6 years and analyzed by microbiological methods and whole-genome sequencing. Epidemiological links among patients were investigated. Ten isolates were collected from 4 patients. Whole-genome sequencing of one isolate from each patient showed that a single strain was shared among them. In addition, one patient was found to have the same strain in two consecutive samplings performed 9 months apart. The strain was nontoxigenic and was susceptible to most antimicrobial agents. Ciprofloxacin resistance was observed in one patient. The idea of transmission of the strain among patients was supported by the occurrence of same-day visits to the CF center. This study demonstrated colonization of CF patients by C. diphtheriae biovar Belfanti (C. belfantii), and the data suggest persistence and transmission of a unique strain during at least 6 years in a single CF patient care center.

Extubation of patients undergoing extracorporeal life support. A retrospective study.

INTRODUCTION: The use of extracorporeal life support (ECLS) is increasing worldwide, in particular for the management of refractory cardiac arrest, cardiogenic shock and post cardiopulmonary bypass ventricular failure. Extubation of patients under extracorporeal membrane oxygenation (ECMO) for respiratory failure is a growing practice for adult and pediatric patients, especially for lung transplantation candidates. Because of potential complications and, specifically, accidental arterial decannulation, extubation of patients under ECLS is not standard practice. Our goal was to evaluate the interest in patient extubation under ECLS. MATERIALS AND METHODS: We performed a monocentric, retrospective study of all ECLS cases between January 2014 and January 2016. We excluded patients who died within the first 48 hours of ECLS. RESULTS: We analyzed 57 of the initial 109 patients included in the study. The initial SOFA score was higher in the non-extubated group under ECLS, without significant difference (8.6 ± 2.8 vs 7.2 ± 2.1, p=0.065). Patients who were not extubated had a higher rate of acquired ventilator pneumonia (61.9% vs 26.7%, p=0.03). Moreover, patients who were extubated under ECLS had better 30-day survival rates (73.3% vs 40.5%, p=0.04). In multivariate analyses, the independent factors associated with mortality were age, duration of ECLS and the lack of extubation under ECLS. CONCLUSION: Extubation of patients under ECLS is safe and feasible. Furthermore, in extubated patients, we observed fewer cases of ventilator-associated pneumonia and better 30-day survival rates.

Liver Fat Content in People with Pituitary Diseases: Influence of Serum IGF1 Levels.

Non-alcoholic fatty liver disease (NAFLD) is commonly associated with obesity, metabolic syndrome, and type 2 diabetes. NAFLD is also seen in patients with endocrinopathies. However, the relationship between endocrine diseases and the development of NAFLD is not well known. In this study, we set out to determine whether liver fat content (LFC) was associated with IGF1 levels in people with pituitary diseases (PD). Eighty-nine patients with pituitary diseases and 74 healthy controls were included in this study. LFC was measured using MRI. Hepatic steatosis was defined as LFC>5.5%. Patients with PD were older, and had a higher BMI than healthy controls. LFC was significantly higher in people with PD than in controls (6.5% vs. 3.2%; p<0.001). LFC was negatively associated with the IGF1 level. The prevalence of steatosis was higher in PD patients than in controls (36.3% vs. 14.8%; p=0.002). In multivariate analysis, which included patients and controls, the predictive variables for steatosis were age, BMI and IGF1 levels, whereas the presence of pituitary diseases and gender were not associated with steatosis. Our data showed that LFC was strongly associated with IGF1 levels. These results suggest that steatosis associated with PD is probably a consequence of a low IGF1 level in these patients.

Tumor Targeting and Three-Dimensional Voxel-Based Dosimetry to Predict Tumor Response, Toxicity, and Survival after Yttrium-90 Resin Microsphere Radioembolization in Hepatocellular Carcinoma.

PURPOSE: To identify predictive factors of tumor response, progression-free survival (PFS), overall survival (OS), and toxicity using three-dimensional (3D) voxel-based dosimetry in patients with intermediate and advanced stage hepatocellular carcinoma (HCC) treated by yttrium-90 (90Y) resin microspheres radioembolization (RE). MATERIALS AND METHODS: From February 2012 to December 2015, 45 90Y resin microspheres RE procedures were performed for HCC (Barcelona Clinic Liver Cancer stage B/C; n = 15/30). Area under the dose-volume histograms (AUDVHs) were calculated from 3D voxel-based dosimetry to measure 90Y dose deposition. Factors associated with tumor control (ie, complete/partial response or stable disease on Modified Response Evaluation Criteria in Solid Tumors) at 6 months were investigated. PFS and OS analyses were performed (Kaplan-Meier). Toxicity was assessed by occurrence of radioembolization-induced liver disease (REILD). RESULTS: Tumor control rate was 40.5% (17/42). Complete tumor targeting (odds ratio = 36.97; 95% confidence interval, 1.83-747; P < .001) and AUDVHtumor (odds ratio = 1.027; 95% confidence interval, 1.002-1.071; P = .033) independently predicted tumor control. AUDVHtumor ≥ 61 Gy predicted tumor control with 76.5% sensitivity and 75% specificity. PFS and OS in patients with incomplete tumor targeting were significantly shorter than in patients with complete tumor targeting (median PFS, 2.7 months [range, 0.8-4.6 months] vs 7.9 months [range, 2.1-39.5 months], P < .001; median OS, 4.5 months [range, 1.4-23 months] vs 19.2 months [range, 2.1-46.9 months], P < .001). Patients with incomplete tumor targeting and AUDVHtumor < 61 Gy, incomplete tumor targeting and AUDVHtumor > 61 Gy, complete tumor targeting and AUDVHtumor < 61 Gy, and AUDVHtumor > 61 Gy had median PFS of 2.7, 1.8, 6.3, and 12.1 months (P < .001). REILD (n = 4; 9.5%) was associated with higher dose delivered to normal liver (P = .04). CONCLUSIONS: Complete tumor targeting and 90Y dose to tumor are independent factors associated with tumor control and clinical outcomes.

Comparable Outcome of Out-of-Hospital Cardiac Arrest and In-Hospital Cardiac Arrest Treated With Extracorporeal Life Support.

Extracorporeal life support (ECLS) has shown benefits in the management of refractory in-hospital cardiac arrest (IHCA) by improving survival. Nonetheless, the results concerning out-of-hospital refractory cardiac arrests (OHCA) remain uncertain. The aim of our investigation was to compare survival between the two groups. We realized a single-center retrospective, observational study of all patients who presented IHCA or OHCA treated with ECLS between 2011 and 2015. Multivariate analysis was realized to determine independent factors associated with mortality. Over the 4-year period, 65 patients were included, 43 in the IHCA group (66.2%), and 22 (33.8%) in the OHCA group. The duration of low flow was significantly longer in the OHCA group (60 vs. 90 min, P = 0.004). Survival to discharge from the hospital was identical in the two groups (27% in the OHCA group vs. 23% in the IHCA group, P = 0.77). All surviving patients in the OHCA group had a cerebral performance categories score of 1-2. In multivariate analysis, we found that the initial lactate level and baseline blood creatinine were independently associated with mortality. We found comparable survival and neurological score in patients who presented IHCA and OHCA treated with ECLS. We believe that appropriate selection of patients and optimization of organ perfusion during resuscitation can lead to good results in patients with OHCA treated with ECLS.

Serratus anterior plane block for minimal invasive heart surgery.

BACKGROUND: Minimal invasive heart surgery (MIHS) presents several benefits, but provides intense and prolonged post-operative pain. Our objective was to compare efficacy of serratus anterior plane block (SAPB) with continuous wound infiltration (CWI) for management of post-operative pain following MIHS. METHODS: It's retrospective, monocentric study between November 2016 to April 2017. The study was performed at the University hospital of Dijon, Burgundy, France. All patients scheduled for MIHS was included. Data was collected retrospectively. During this period, 20 patients had SAPB and 26 had CWI. SAPB was performed before extubation with a single injection of 0.5 mg/kg of ropivacaïne (5 mg/ml). In the CWI group, catheter was inserted in the subcutaneous space by the surgeon at the end of the procedure. A 10 ml bolus of ropivacaïne (7.5 mg/mL) was followed by a continuous infusion (2 mg/ml) between 7 and 12 ml/h for 48 h. Morphine consumption and visual analog score (VAS) were recorded for 48 h. Length of stay in intensive care unit and hospital was also collected. RESULTS: Morphine consumption and VAS score were significantly lower in SAPB group (p < 0.01). Length of stay in intensive care and hospital was significantly was decreased in SAPB group. CONCLUSION: SAPB appears effective in reducing postoperative MIHS pain.

Liver and biliary damages following transarterial chemoembolization of hepatocellular carcinoma: comparison between drug-eluting beads and lipiodol emulsion.

OBJECTIVES: To compare transarterial chemoembolization (TACE)-related hepatic toxicities of conventional TACE (cTACE) and drug-eluting beads TACE (DEB-TACE) in patients with intermediate-stage hepatocellular carcinoma. METHODS: In this retrospective study, 151 consecutive patients undergoing cTACE or DEB-TACE and MRI 3-6 weeks before and after therapy were included. Toxicity was assessed on imaging (global hepatic damages (GHD), overall biliary injuries, biliary cast, bile duct dilatation, intrahepatic biloma, portal thrombosis), and clinico-biological follow-ups. Tumour response, time to progression (TTP), and overall survival were assessed. Factors influencing complication rate were identified by generalized equation logistic regression model. RESULTS: Biliary injuries and intrahepatic biloma incidence were significantly higher following DEB-TACE (p < 0.001). DEB-TACE showed a significant increased risk of GHD (OR: 3.13 [1.74-5.63], p < 0.001) and biliary injuries (OR: 4.53 [2.37-8.67], p < 0.001). A significant relationship was found between baseline prothrombin value and GHD, biliary injuries and intrahepatic biloma (all p < 0.01), and between the dose of chemotherapy and intrahepatic biloma (p = 0.001). Only TTP was significantly shorter following DEB-TACE compared to cTACE (p = 0.025). CONCLUSIONS: DEB-TACE was associated with increased hepatic toxicities compared to cTACE. GHD, biliary injuries, and intrahepatic biloma were more frequently observed with high baseline prothrombin value, suggesting that cTACE might be more appropriate than DEB-TACE in patients with less advanced cirrhosis. KEY POINTS: • DEB-TACE demonstrated more therapy-related hepatic locoregional complications compared to cTACE. • TACE-related hepatic locoregional toxicities occurred more frequently with high baseline PT value. • cTACE may be more appropriate in patients with high baseline PT value.

Significance of Prior Digestive Colonization With Extended-Spectrum ß-Lactamase-Producing Enterobacteriaceae in Patients With Ventilator-Associated Pneumonia.

OBJECTIVES: Ventilator-associated pneumonia is frequent in ICUs. Extended-spectrum ß-lactamase-producing Enterobacteriaceae are difficult-to-treat pathogens likely to cause ventilator-associated pneumonia. We sought to assess the interest of screening for extended-spectrum ß-lactamase-producing Enterobacteriaceae rectal carriage as a way to predict their involvement in ventilator-associated pneumonia. DESIGN: A retrospective cohort study of patients with suspected ventilator-associated pneumonia in a medical ICU was conducted. PATIENTS: Every patient admitted between January 2006 and August 2013 was eligible if subjected to mechanical ventilation for more than 48 hours. Each patient with suspected ventilator-associated pneumonia was included in the cohort. Active surveillance culture for extended-spectrum ß-lactamase-producing Enterobacteriaceae detection was routinely performed in all patients at admission and then weekly throughout the study period. Extended-spectrum ß-lactamase colonization was defined by the isolation of at least one extended-spectrum ß-lactamase-producing Enterobacteriaceae from rectal swab culture. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among 587 patients with suspected ventilator-associated pneumonia, 40 (6.8%) were colonized with extended-spectrum ß-lactamase-producing Enterobacteriaceae prior to the development of pneumonia. Over the study period, 20 patients (3.4%) had ventilator-associated pneumonia caused by extended-spectrum ß-lactamase-producing Enterobacteriaceae; of whom, 17 were previously detected as being colonized with extended-spectrum ß-lactamase-producing Enterobacteriaceae. Sensitivity and specificity of prior extended-spectrum ß-lactamase-producing Enterobacteriaceae colonization as a predictor of extended-spectrum ß-lactamase-producing Enterobacteriaceae involvement in ventilator-associated pneumonia were 85.0% and 95.7%, respectively. The positive and negative predictive values were 41.5% and 99.4%, respectively. The positive likelihood ratio was 19.8. CONCLUSIONS: Screening for extended-spectrum ß-lactamase-producing Enterobacteriaceae digestive colonization by weekly active surveillance cultures could reliably exclude the risk of the involvement of such pathogens in patients with ventilator-associated pneumonia in low-prevalence area.

A Clonal Lineage of Fusarium oxysporum Circulates in the Tap Water of Different French Hospitals.

Fusarium oxysporum is typically a soilborne fungus but can also be found in aquatic environments. In hospitals, water distribution systems may be reservoirs for the fungi responsible for nosocomial infections. F. oxysporum was previously detected in the water distribution systems of five French hospitals. Sixty-eight isolates from water representative of all hospital units that were previously sampled and characterized by translation elongation factor 1α sequence typing were subjected to microsatellite analysis and full-length ribosomal intergenic spacer (IGS) sequence typing. All but three isolates shared common microsatellite loci and a common two-locus sequence type (ST). This ST has an international geographical distribution in both the water networks of hospitals and among clinical isolates. The ST dominant in water was not detected among 300 isolates of F. oxysporum that originated from surrounding soils. Further characterization of 15 isolates by vegetative compatibility testing allowed us to conclude that a clonal lineage of F. oxysporum circulates in the tap water of the different hospitals. IMPORTANCE: We demonstrated that a clonal lineage of Fusarium oxysporum inhabits the water distribution systems of several French hospitals. This clonal lineage, which appears to be particularly adapted to water networks, represents a potential risk for human infection and raises questions about its worldwide distribution.

Contribution of the computed tomography of the anatomical aspects of the sphenoid sinuses to forensic identification.

INTRODUCTION: Body identification is the cornerstone of forensic investigation. It can be performed using radiographic techniques, if antemortem images are available. This study was designed to assess the value of visual comparison of the computed tomography (CT) anatomical aspects of the sphenoid sinuses, in forensic individual identification, especially if antemortem dental records, fingerprints or DNA samples are not available. MATERIAL AND METHODS: This retrospective work took place in a French university hospital. The supervisor of this study randomly selected from the picture archiving and communication system (PACS), 58 patients who underwent one (16 patients) or two (42 patients) head CT in various neurological contexts. To avoid bias, those studies were prepared (anonymized, and all the head structures but the sphenoid sinuses were excluded), and used to constitute two working lists of 50 (42+8) CT studies of the sphenoid sinuses. An anatomical classification system of the sphenoid sinuses anatomical variations was created based on the anatomical and surgical literature. In these two working lists, three blinded readers had to identify, using the anatomical system and subjective visual comparison, 42 pairs of matched studies, and 16 unmatched studies. Readers were blinded from the exact numbers of matching studies. RESULTS: Each reader correctly identified the 42 pairs of CT with a concordance of 100% [97.5% confidence interval: 91-100%], and the 16 unmatched CT with a concordance of 100% [97.5% confidence interval: 79-100%]. Overall accuracy was 100%. CONCLUSION: Our study shows that establishing the anatomical concordance of the sphenoid sinuses by visual comparison could be used in personal identification. This easy method, based on a frequently and increasingly prescribed exam, still needs to be assessed on a postmortem cohort.

Rotavirus P[8] Infections in Persons with Secretor and Nonsecretor Phenotypes, Tunisia.

To determine whether rotavirus infections are linked to secretor status, we studied samples from children in Tunisia with gastroenteritis. We phenotyped saliva for human blood group antigens and tested feces for rotavirus. Rotavirus was detected in 32/114 patients. Secretor genotyping showed that P[8] rotavirus infected secretors and nonsecretors, and infection correlated with presence of Lewis antigen.

Diagnostic Accuracy of Seven Commercial Assays for Rapid Detection of Group A Rotavirus Antigens.

Seven commercial immunochromatographic assays intended for the detection of group A rotavirus antigens in human stool samples were evaluated. These assays showed similar levels of diagnostic accuracy and were suitable for the detection of rotavirus in patients with acute gastroenteritis but missed some asymptomatic rotavirus shedding identified by real-time reverse transcription-PCR.

Intravoxel incoherent motion diffusion-weighted imaging in the liver: comparison of mono-, bi- and tri-exponential modelling at 3.0-T.

PURPOSE: To determine whether a mono-, bi- or tri-exponential model best fits the intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) signal of normal livers. MATERIALS AND METHODS: The pilot and validation studies were conducted in 38 and 36 patients with normal livers, respectively. The DWI sequence was performed using single-shot echoplanar imaging with 11 (pilot study) and 16 (validation study) b values. In each study, data from all patients were used to model the IVIM signal of normal liver. Diffusion coefficients (Di ± standard deviations) and their fractions (fi ± standard deviations) were determined from each model. The models were compared using the extra sum-of-squares test and information criteria. RESULTS: The tri-exponential model provided a better fit than both the bi- and mono-exponential models. The tri-exponential IVIM model determined three diffusion compartments: a slow (D1 = 1.35 ± 0.03 × 10(-3) mm(2)/s; f1 = 72.7 ± 0.9 %), a fast (D2 = 26.50 ± 2.49 × 10(-3) mm(2)/s; f2 = 13.7 ± 0.6 %) and a very fast (D3 = 404.00 ± 43.7 × 10(-3) mm(2)/s; f3 = 13.5 ± 0.8 %) diffusion compartment [results from the validation study]. The very fast compartment contributed to the IVIM signal only for b values ≤15 s/mm(2) CONCLUSION: The tri-exponential model provided the best fit for IVIM signal decay in the liver over the 0-800 s/mm(2) range. In IVIM analysis of normal liver, a third very fast (pseudo)diffusion component might be relevant. KEY POINTS: • For normal liver, tri-exponential IVIM model might be superior to bi-exponential • A very fast compartment (D = 404.00 ± 43.7 × 10 (-3) mm (2) /s; f = 13.5 ± 0.8 %) is determined from the tri-exponential model • The compartment contributes to the IVIM signal only for b ≤ 15 s/mm(2).

Absolute Humidity Influences the Seasonal Persistence and Infectivity of Human Norovirus.

Norovirus (NoV) is one of the main causative agents of acute gastroenteritis worldwide. In temperate climates, outbreaks peak during the winter season. The mechanism by which climatic factors influence the occurrence of NoV outbreaks is unknown. We hypothesized that humidity is linked to NoV seasonality. Human NoV is not cultivatable, so we used cultivatable murine norovirus (MNV) as a surrogate to study its persistence when exposed to various levels of relative humidity (RH) from low (10% RH) to saturated (100% RH) conditions at 9 and 25°C. In addition, we conducted similar experiments with virus-like particles (VLPs) from the predominant GII-4 norovirus and studied changes in binding patterns to A, B, and O group carbohydrates that might reflect capsid alterations. The responses of MNV and VLP to humidity were somewhat similar, with 10 and 100% RH exhibiting a strong conserving effect for both models, whereas 50% RH was detrimental for MNV infectivity and VLP binding capacity. The data analysis suggested that absolute humidity (AH) rather than RH is the critical factor for keeping NoV infectious, with an AH below 0.007 kg water/kg air being favorable to NoV survival. Retrospective surveys of the meteorological data in Paris for the last 14 years showed that AH average values have almost always been below 0.007 kg water/kg air during the winter (i.e., 0.0046 ± 0.0014 kg water/kg air), and this finding supports the fact that low AH provides an ideal condition for NoV persistence and transmission during cold months.