CXCL12 targets the primary cilium cAMP/cGMP ratio to regulate cell polarity during migration

Directed cell migration requires sustained cell polarisation. In migrating cortical interneurons, nuclear movements are directed towards the centrosome that organises the primary cilium signalling hub. Primary cilium-elicited signalling, and how it affects migration, remain however ill characterised. Here, we show that altering cAMP/cGMP levels in the primary cilium by buffering cAMP, cGMP or by locally increasing cAMP, influences the polarity and directionality of migrating interneurons, whereas buffering cAMP or cGMP in the apposed centrosome compartment alters their motility. Remarkably, we identify CXCL12 as a trigger that targets the ciliary cAMP/cGMP ratio to promote sustained polarity and directed migration. We thereby uncover cAMP/cGMP levels in the primary cilium as a major target of extrinsic cues and as the steering wheel of neuronal migration.

Herpesvirus reactivation during severe COVID-19 and high rate of immune defect

OBJECTIVE

We assessed herpesvirus reactivation in severe SARS-CoV-2 infection.

METHODS

Retrospective study including consecutive patients admitted to an onco-hematology intensive care unit (ICU) for severe COVID-19. Replication of EBV, CMV, and HSV was evaluated. Competing risk analyses were used to assess the cumulative risk of viral reactivation, and time-dependent Cox and Fine and Gray models to assess risk factors for viral reactivation.

RESULTS

Among 100 patients, 38 were immunocompromised. Sixty-three patients presented viral reactivation (12% for HSV, 58% EBV and 19% CMV). Symptomatic patients received treatment. Overall cumulative incidence of viral reactivation was 56.1% [55.9-56.4] at 10 days. After adjustment, a preexisting hematological malignancy (sHR [95%CI]=0.31 [0.11-0.85]) and solid organ transplantation (sHR [95% CI]=2.09 [1.13-3.87]) remained independently associated with viral reactivation. Viral reactivation (P=0.34) was not associated with mortality.

CONCLUSIONS

Incidence of herpesvirus reactivation in patients admitted to the ICU for severe COVID-19 was high, but rarely required antiviral treatment.

The Orphan GPCR Receptor, GPR88, Interacts with Nuclear Protein Partners in the Cerebral Cortex

GPR88 is an orphan G-protein-coupled receptor (GPCR) highly expressed in striatal medium spiny neurons (MSN), also found in cortical neurons at low level. In MSN, GPR88 has a canonical GPCR plasma membrane/cytoplasmic expression, whereas in cortical neurons, we previously reported an atypical intranuclear localization. Molecular size analysis suggests that GPR88, expressed in plasma membrane of MSN or in nuclear compartment of cortical neurons, corresponds to the full-length protein. By transfection of cortical neurons, we showed that GPR88 fluorescent chimeras exhibit a nuclear localization. This localization is contingent on the third intracytoplasmic loop and C-terminus domains, even though these domains do not contain any known nuclear localization signals (NLS). Using yeast two-hybrid screening with these domains, we identified the nuclear proteins ATRX, TOP2B, and BAZ2B, all involved in chromatin remodeling, as potential protein partners of GPR88. We also validated the interaction of GPR88 with these nuclear proteins by proximity ligation assay on cortical neurons in culture and coimmunoprecipitation experiments on cortical extracts from GPR88 wild-type (WT) and knockout (KO) mice. The identification of GPR88 subcellular partners may provide novel functional insights for nonclassical modes of GPCR action that could be relevant in the maturating process of neocortical neurons.

YIF1B mutations cause a post-natal neurodevelopmental syndrome associated with Golgi and primary cilium alterations

Human post-natal neurodevelopmental delay is often associated with cerebral alterations that can lead, by themselves or associated with peripheral deficits, to premature death. Here, we report the clinical features of 10 patients from six independent families with mutations in the autosomal YIF1B gene encoding a ubiquitous protein involved in anterograde traffic from the endoplasmic reticulum to the cell membrane, and in Golgi apparatus morphology. The patients displayed global developmental delay, motor delay, visual deficits with brain MRI evidence of ventricle enlargement, myelination alterations and cerebellar atrophy. A similar profile was observed in the Yif1b knockout (KO) mouse model developed to identify the cellular alterations involved in the clinical defects. In the CNS, mice lacking Yif1b displayed neuronal reduction, altered myelination of the motor cortex, cerebellar atrophy, enlargement of the ventricles, and subcellular alterations of endoplasmic reticulum and Golgi apparatus compartments. Remarkably, although YIF1B was not detected in primary cilia, biallelic YIF1B mutations caused primary cilia abnormalities in skin fibroblasts from both patients and Yif1b-KO mice, and in ciliary architectural components in the Yif1b-KO brain. Consequently, our findings identify YIF1B as an essential gene in early post-natal development in human, and provide a new genetic target that should be tested in patients developing a neurodevelopmental delay during the first year of life. Thus, our work is the first description of a functional deficit linking Golgipathies and ciliopathies, diseases so far associated exclusively to mutations in genes coding for proteins expressed within the primary cilium or related ultrastructures. We therefore propose that these pathologies should be considered as belonging to a larger class of neurodevelopmental diseases depending on proteins involved in the trafficking of proteins towards specific cell membrane compartments.

Key role of the 5-HT1A receptor addressing protein Yif1B in serotonin neurotransmission and SSRI treatment

BACKGROUND

Altered function of serotonin receptor 1A (5-HT1AR) has been consistently implicated in anxiety, major depressive disorder and resistance to antidepressants. Mechanisms by which the function of 5-HT1AR (expressed as an autoreceptor in serotonergic raphe neurons and as a heteroreceptor in serotonin [5-HT] projection areas) is altered include regulation of its expression, but 5-HT1AR trafficking may also be involved.

METHODS

We investigated the consequences of the lack of Yif1B (the 5-HT1AR trafficking protein) on 5-HT neurotransmission in mice, and whether Yif1B expression might be affected under conditions known to alter 5-HT neurotransmission, such as anxious or depressive states or following treatment with fluoxetine (a selective serotonin reuptake inhibitor) in humans, monkeys and mice.

RESULTS

Compared with wild-type mice, Yif1B-knockout mice showed a significant decrease in the forebrain density of 5-HT projection fibres and a hypofunctionality of 5-HT1A autoreceptors expressed on raphe 5-HT neurons. In addition, social interaction was less in Yif1B-knockout mice, which did not respond to the antidepressant-like effect of acute fluoxetine injection. In wild-type mice, social defeat was associated with downregulated Yif1B mRNA in the prefrontal cortex, and chronic fluoxetine treatment increased Yif1B expression. The expression of Yif1B was also downregulated in the postmortem prefrontal cortex of people with major depressive disorder and upregulated after chronic treatment with a selective serotonin reuptake inhibitor in monkeys.

LIMITATIONS

We found sex differences in Yif1B expression in humans and monkeys, but not in mice under the tested conditions.

CONCLUSION

These data support the concept that Yif1B plays a critical role in 5-HT1AR functioning and brain 5-HT homeostasis. The opposite changes in its expression observed in anxious or depressive states and after therapeutic fluoxetine treatment suggest that Yif1B might be involved in vulnerability to anxiety and depression, and fluoxetine efficacy.

Report of the first AKI Round Table meeting: an initiative of the ESICM AKI Section

PURPOSE

Critical Care Nephrology is an emerging sub-specialty of Critical Care. Despite increasing awareness about the serious impact of acute kidney injury (AKI) and renal replacement therapy (RRT), important knowledge gaps persist. This report represents a summary of a 1-day meeting of the AKI section of the European Society of Intensive Care Medicine (ESICM) identifying priorities for future AKI research.

METHODS

International Members of the AKI section of the ESICM were selected and allocated to one of three subgroups: "AKI diagnosis and evaluation", "Medical management of AKI" and "Renal Replacement Therapy for AKI." Using a modified Delphi methodology, each group identified knowledge gaps and developed potential proposals for future collaborative research.

RESULTS

The following key research projects were developed: Systematic reviews: (a) epidemiology of AKI with stratification by patient cohorts and diagnostic criteria; (b) role of higher blood pressure targets in patients with hypertension admitted to the Intensive Care Unit, and (c) specific clearance characteristics of different modalities of continuous renal replacement therapy (CRRT). Observational studies: (a) epidemiology of critically ill patients according to AKI duration, and (b) current clinical practice of CRRT. Intervention studies:( a) Comparison of different blood pressure targets in critically ill patients with hypertension, and (b) comparison of clearance of solutes with various molecular weights between different CRRT modalities.

CONCLUSION

Consensus was reached on a future research agenda for the AKI section of the ESICM.

Diagnostic et Prise en Charge de l’Acidose Métabolique Recommandations formalisées d’experts communes Société de réanimation de langue française (SRLF) – Société française de médecine d’urgence (SFMU)

L’acidose métabolique est un trouble fréquemment rencontré en médecine d’urgence et en médecine intensive réanimation. La littérature s’étant enrichie de nouvelles données concernant la prise en charge de l’acidose métabolique, la Société de Réanimation de Langue Française (SRLF) et la Société Française de Médecine d’Urgence (SFMU) ont élaboré des recommandations formalisées d’experts selon la méthodologie GRADE. Les champs de la stratégie diagnostique, de l’orientation et de la prise en charge thérapeutique ont été traités et vingt-neuf recommandations ont été formulées : quatre recommandations fortes (Grade 1), dix recommandations faibles (Grade 2) et quinze avis d’experts. Toutes ont obtenu un accord fort. L’application des méthodes d’Henderson-Hasselbalch et de Stewart pour le diagnostic du mécanisme de l’acidose métabolique est discutée et un algorithme diagnostique est proposé. L’utilisation de la cétonémie et des lactatémies veineuse et capillaire est également traitée. L’intérêt du pH, de la lactatémie et de sa cinétique pour l’orientation des patients en pré-hospitalier et aux urgences est envisagé. Enfin, les modalités de l’insulinothérapie au cours de l’acidocétose diabétique, les indications de la perfusion de bicarbonate de sodium et de l’épuration extra-rénale ainsi que les modalités de la ventilation mécanique au cours des acidoses métaboliques sévères sont traitées dans la prise en charge thérapeutique.

Protein interacting with Amyloid Precursor Protein tail-1 (PAT1) is involved in early endocytosis

Protein interacting with Amyloid Precursor Protein (APP) tail 1 (PAT1) also called APPBP2 or Ara 67 has different targets such as APP or androgen receptor and is expressed in several tissues. PAT1 is known to be involved in the subcellular trafficking of its targets. We previously observed in primary neurons that PAT1 is poorly associated with APP at the cell surface. Here we show that PAT1 colocalizes with vesicles close to the cell surface labeled with Rab5, Rab4, EEA1 and Rabaptin-5 but not with Rab11 and Rab7. Moreover, PAT1 expression regulates the number of EEA1 and Rab5 vesicles, and endocytosis/recycling of the transferrin receptor. In addition, low levels of PAT1 decrease the size of transferrin-colocalized EEA1 vesicles with time following transferrin uptake. Finally, overexpression of the APP binding domain to PAT1 is sufficient to compromise endocytosis. Altogether, these data suggest that PAT1 is a new actor in transferrin early endocytosis. Whether this new function of PAT1 may have consequences in pathology remains to be determined.

GLS1 Mutant Mice Display Moderate Alterations of Hippocampal Glutamatergic Neurotransmission Associated with Specific Adaptive Behavioral Changes

Significant alterations in glutamatergic neurotransmission have been reported in major depressive disorder (MDD) that could underlie psychiatric traits. Studies were mainly interested in synaptic dysfunction in the prefrontal cortex, a key structure involved in depressive-like behavior, however hippocampus has been shown to be important in MDD. As cognitive deficits such as hippocampus-memory process were observed in MDD, we investigated in a mild hypoglutamatergic model behaviors related to depression and memory, synaptic transmission parameters and glutamatergic state specifically in the hippocampus. We thus characterized these phenotypes in adult male mice partially depleted in glutaminase type 1 or GLS1 (GLS1 HET), the enzyme responsible for glutamate synthesis in neurons, that we previously characterized as displaying moderate lower levels of glutamate in brain. We showed that GLS1 mutant mice display AMPA-R-mediated response deficits after prolonged repetitive stimulation with electrophysiological recording and inability to sustain glutamate release by microdialysis experiments with no consequences on behavioral spatial learning performances. However, their ability to escape from unpleasant but repeated escapable condition was attenuated whereas they were more immobile in the unescapable situation in the FST during re-test. These results show that GLS1 mutant mice display moderate impairments of hippocampal glutamatergic neurotransmission and moderate changes in adaptive behaviors that have been shown to participate to the development of depressive-like state.

ICU survival and need of renal replacement therapy with respect to AKI duration in critically ill patients

BACKGROUND

Transient and persistent acute kidney injury (AKI) could share similar physiopathological mechanisms. The objective of our study was to assess prognostic impact of AKI duration on ICU mortality.

DESIGN

Retrospective analysis of a prospective database via cause-specific model, with 28-day ICU mortality as primary end point, considering discharge alive as a competing event and taking into account time-dependent nature of renal recovery. Renal recovery was defined as a decrease of at least one KDIGO class compared to the previous day.

SETTING

23 French ICUs.

PATIENTS

Patients of a French multicentric observational cohort were included if they suffered from AKI at ICU admission between 1996 and 2015.

INTERVENTION

None.

RESULTS

A total of 5242 patients were included. Initial severity according to KDIGO creatinine definition was AKI stage 1 for 2458 patients (46.89%), AKI stage 2 for 1181 (22.53%) and AKI stage 3 for 1603 (30.58%). Crude 28-day ICU mortality according to AKI severity was 22.74% (n = 559), 27.69% (n = 327) and 26.26% (n = 421), respectively. Renal recovery was experienced by 3085 patients (58.85%), and its rate was significantly different between AKI severity stages (P < 0.01). Twenty-eight-day ICU mortality was independently lower in patients experiencing renal recovery [CSHR 0.54 (95% CI 0.46-0.63), P < 0.01]. Lastly, RRT requirement was strongly associated with persistent AKI whichever threshold was chosen between day 2 and 7 to delineate transient from persistent AKI.

CONCLUSIONS

Short-term renal recovery, according to several definitions, was independently associated with higher mortality and RRT requirement. Moreover, distinction between transient and persistent AKI is consequently a clinically relevant surrogate outcome variable for diagnostic testing in critically ill patients.

Outcome in patients perceived as receiving excessive care across different ethical climates: a prospective study in 68 intensive care units in Europe and the USA

Purpose

Whether the quality of the ethical climate in the intensive care unit (ICU) improves the identification of patients receiving excessive care and affects patient outcomes is unknown.

Methods

In this prospective observational study, perceptions of excessive care (PECs) by clinicians working in 68 ICUs in Europe and the USA were collected daily during a 28-day period. The quality of the ethical climate in the ICUs was assessed via a validated questionnaire. We compared the combined endpoint (death, not at home or poor quality of life at 1 year) of patients with PECs and the time from PECs until written treatment-limitation decisions (TLDs) and death across the four climates defined via cluster analysis.

Results

Of the 4747 eligible clinicians, 2992 (63%) evaluated the ethical climate in their ICU. Of the 321 and 623 patients not admitted for monitoring only in ICUs with a good (n = 12, 18%) and poor (n = 24, 35%) climate, 36 (11%) and 74 (12%), respectively were identified with PECs by at least two clinicians. Of the 35 and 71 identified patients with an available combined endpoint, 100% (95% CI 90.0–1.00) and 85.9% (75.4–92.0) (P = 0.02) attained that endpoint. The risk of death (HR 1.88, 95% CI 1.20–2.92) or receiving a written TLD (HR 2.32, CI 1.11–4.85) in patients with PECs by at least two clinicians was higher in ICUs with a good climate than in those with a poor one. The differences between ICUs with an average climate, with (n = 12, 18%) or without (n = 20, 29%) nursing involvement at the end of life, and ICUs with a poor climate were less obvious but still in favour of the former.

Conclusion

Enhancing the quality of the ethical climate in the ICU may improve both the identification of patients receiving excessive care and the decision-making process at the end of life.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5231-8) contains supplementary material, which is available to authorized users.

Renal recovery after acute kidney injury

Acute kidney injury (AKI) is a frequent complication of critical illness and carries a significant risk of short- and long-term mortality, chronic kidney disease (CKD) and cardiovascular events. The degree of renal recovery from AKI may substantially affect these long-term endpoints. Therefore maximising recovery of renal function should be the goal of any AKI prevention and treatment strategy. Defining renal recovery is far from straightforward due in part to the limitations of the tests available to assess renal function. Here, we discuss common pitfalls in the evaluation of renal recovery and provide suggestions for improved assessment in the future. We review the epidemiology of renal recovery and of the association between AKI and the development of CKD. Finally, we stress the importance of post-discharge follow-up of AKI patients and make suggestions for its incorporation into clinical practice. Summary key points are that risk factors for non-recovery of AKI are age, CKD, comorbidity, higher severity of AKI and acute disease scores. Second, AKI and CKD are mutually related and seem to have a common denominator. Third, despite its limitations full recovery of AKI may best be defined as the absence of AKI criteria, and partial recovery as a fall in AKI stage. Fourth, after an episode of AKI, serial follow-up measurements of serum creatinine and proteinuria are warranted to diagnose renal impairment and prevent further progression. Measures to promote recovery are similar to those preventing renal harm. Specific interventions promoting repair are still experimental.

Noninvasive ventilation during acute respiratory distress syndrome in patients with cancer: Trends in use and outcome

PURPOSE

The objectives of our study were to describe the outcome of patients with malignancies treated for acute respiratory distress syndrome (ARDS) with noninvasive ventilation (NIV) and to evaluate factors associated with NIV failure.

METHODS

Post hoc analysis of a multicenter database within 20 years was performed. All patients with malignancies and Berlin ARDS definition were included. Noninvasive ventilation use was defined as NIV lasting more than 1 hour, whereas failure was defined as a subsequent requirement of invasive ventilation. Conditional backward logistic regression analyses were conducted.

RESULTS

A total of 1004 met the Berlin definition of ARDS. Noninvasive ventilation was used in 387 patients (38.6%) and NIV failure occurred in 71%, with an in-hospital mortality of 62.7%. Severity of ARDS defined by the partial pressure arterial oxygen and fraction of inspired oxygen ratio (odds ratio [OR], 2.20; 95% confidence interval [CI], 1.15-4.19), pulmonary infection (OR, 1.81; 95% CI, 1.08-3.03), and modified Sequential Organ Failure Assessment (SOFA) score (OR, 1.13; 95% CI, 1.06-1.21) were associated with NIV failure. Factors associated with hospital mortality were NIV failure (OR, 2.52; 95% CI, 1.56-4.07), severe ARDS as compared with mild ARDS (OR, 1.89; 95% CI, 1.05-1.19), and modified SOFA score (OR, 1.12; 95% CI, 1.05-1.19).

CONCLUSION

Noninvasive ventilation failure in ARDS patients with malignancies is frequent and related to ARDS severity, SOFA score, and pulmonary infection-related ARDS. Noninvasive ventilation failure is associated with in-hospital mortality.

GABAB receptor cell-surface export is controlled by an endoplasmic reticulum gatekeeper

Endoplasmic reticulum (ER) release and cell-surface export of many G protein-coupled receptors (GPCRs) are tightly regulated. For gamma-aminobutyric acid (GABA)B receptors of GABA, the major mammalian inhibitory neurotransmitter, the ligand-binding GB1 subunit is maintained in the ER by unknown mechanisms in the absence of hetero-dimerization with the GB2 subunit. We report that GB1 retention is regulated by a specific gatekeeper, PRAF2. This ER resident transmembrane protein binds to GB1, preventing its progression in the biosynthetic pathway. GB1 release occurs upon competitive displacement from PRAF2 by GB2. PRAF2 concentration, relative to that of GB1 and GB2, tightly controls cell-surface receptor density and controls GABAB function in neurons. Experimental perturbation of PRAF2 levels in vivo caused marked hyperactivity disorders in mice. These data reveal an unanticipated major impact of specific ER gatekeepers on GPCR function and identify PRAF2 as a new molecular target with therapeutic potential for psychiatric and neurological diseases involving GABAB function.

Developmental and adult expression patterns of the G-protein-coupled receptor GPR88 in the rat: Establishment of a dual nuclear-cytoplasmic localization

GPR88 is a neuronal cerebral orphan G-protein-coupled receptor (GPCR) that has been linked to various psychiatric disorders. However, no extensive description of its localization has been provided so far. Here, we investigate the spatiotemporal expression of the GPR88 in prenatal and postnatal rat tissues by using in situ hybridization and immunohistochemistry. GPR88 protein was initially detected at embryonic day 16 (E16) in the striatal primordium. From E16-E20 to adulthood, the highest expression levels of both protein and mRNA were observed in striatum, olfactory tubercle, nucleus accumbens, amygdala, and neocortex, whereas in spinal cord, pons, and medulla GPR88 expression remains discrete. We observed an intracellular redistribution of GPR88 during cortical lamination. In the cortical plate of the developing cortex, GPR88 presents a classical GPCR plasma membrane/cytoplasmic localization that shifts, on the day of birth, to nuclei of neurons progressively settling in layers V to II. This intranuclear localization remains throughout adulthood and was also detected in monkey and human cortex as well as in the amygdala and hypothalamus of rats. Apart from the central nervous system, GPR88 was transiently expressed at high levels in peripheral tissues, including adrenal cortex (E16-E21) and cochlear ganglia (E19-P3), and also at moderate levels in retina (E18-E19) and spleen (E21-P7). The description of the GPR88 anatomical expression pattern may provide precious functional insights into this novel receptor. Furthermore, the GRP88 nuclear localization suggests nonclassical GPCR modes of action of the protein that could be relevant for cortical development and psychiatric disorders. J. Comp. Neurol. 524:2776-2802, 2016. © 2016 Wiley Periodicals, Inc.

Numerical comparison of acoustic wedge models, with application to ultrasonic telemetry

Ultrasonic telemetry imaging systems are used to monitor such immersed structures as main vessels of nuclear reactors. The interaction between acoustic beams and targets involves scattering phenomena, mainly specular reflection and tip diffraction. In order to assist in the design of imaging systems, a simulation tool is required for the accurate modeling of such phenomena. Relevant high-frequency scattering models have been developed in electromagnetic applications, in particular, the geometrical optics (GO), Geometrical Theory of Diffraction (GTD) and its uniform corrections (UAT and UTD), Kirchhoff approximation (KA) and Physical Theory of Diffraction (PTD). Before adopting any of them for simulation of scattering of acoustic waves by edged immersed rigid bodies, it is important to realize that in acoustics the characteristic dimension to the wave length ratio is usually considerably smaller than in electromagnetics and a further study is required to identify models' advantages, disadvantages and regions of applicability. In this paper their numerical comparison is carried out. As the result, the most suitable algorithm is identified for simulating ultrasonic telemetry of immersed rigid structures.

Protein interactome mining defines melatonin MT1 receptors as integral component of presynaptic protein complexes of neurons

In mammals, the hormone melatonin is mainly produced by the pineal gland with nocturnal peak levels. Its peripheral and central actions rely either on its intrinsic antioxidant properties or on binding to melatonin MT1 and MT2 receptors, belonging to the G protein-coupled receptor (GPCR) super-family. Melatonin has been reported to be involved in many functions of the central nervous system such as circadian rhythm regulation, neurotransmission, synaptic plasticity, memory, sleep, and also in Alzheimer's disease and depression. However, little is known about the subcellular localization of melatonin receptors and the molecular aspects involved in neuronal functions of melatonin. Identification of protein complexes associated with GPCRs has been shown to be a valid approach to improve our understanding of their function. By combining proteomic and genomic approaches we built an interactome of MT1 and MT2 receptors, which comprises 378 individual proteins. Among the proteins interacting with MT1 , but not with MT2 , we identified several presynaptic proteins, suggesting a potential role of MT1 in neurotransmission. Presynaptic localization of MT1 receptors in the hypothalamus, striatum, and cortex was confirmed by subcellular fractionation experiments and immunofluorescence microscopy. MT1 physically interacts with the voltage-gated calcium channel Cav 2.2 and inhibits Cav 2.2-promoted Ca(2+) entry in an agonist-independent manner. In conclusion, we show that MT1 is part of the presynaptic protein network and negatively regulates Cav 2.2 activity, providing a first hint for potential synaptic functions of MT1.

A system model for ultrasonic NDT based on the Physical Theory of Diffraction (PTD)

Simulation of ultrasonic Non Destructive Testing (NDT) is helpful for evaluating performances of inspection techniques and requires the modelling of waves scattered by defects. Two classical flaw scattering models have been previously usually employed and evaluated to deal with inspection of planar defects, the Kirchhoff approximation (KA) for simulating reflection and the Geometrical Theory of Diffraction (GTD) for simulating diffraction. Combining them so as to retain advantages of both, the Physical Theory of Diffraction (PTD) initially developed in electromagnetism has been recently extended to elastodynamics. In this paper a PTD-based system model is proposed for simulating the ultrasonic response of crack-like defects. It is also extended to provide good description of regions surrounding critical rays where the shear diffracted waves and head waves interfere. Both numerical and experimental validation of the PTD model is carried out in various practical NDT configurations, such as pulse echo and Time of Flight Diffraction (TOFD), involving both crack tip and corner echoes. Numerical validation involves comparison of this model with KA and GTD as well as the Finite-Element Method (FEM).

Insights into Serotonin Receptor Trafficking: Cell Membrane Targeting and Internalization

Serotonin receptors (5-HTRs) mediate both central and peripheral control on numerous physiological functions such as sleep/wake cycle, thermoregulation, food intake, nociception, locomotion, sexual behavior, gastrointestinal motility, blood coagulation, and cardiovascular homeostasis. Six families of the G-protein-coupled receptors comprise most of serotonin receptors besides the conserved 5-HT3R Cys-loop type which belongs to the family of Cys-loop ligand-gated cation channel receptors. Many of these receptors are targets of pharmaceutical drugs, justifying the importance for elucidating their coupling, signaling and functioning. Recently, special interest has been focused on their trafficking inside cell lines or neurons in conjunction with their interaction with partner proteins. In this review, we describe the trafficking of 5-HTRs including their internalization, desensitization, or addressing to the plasma membrane depending on specific mechanisms which are peculiar for each class of serotonin receptor.

Acute renal failure is prevalent in patients with thrombotic thrombocytopenic purpura associated with low plasma ADAMTS13 activity

BACKGROUND

Among patients with thrombotic microangiopathies, acute kidney injury (AKI) is the hallmark of hemolytic uremic syndrome (HUS) and is largely underestimated in patients with thrombotic thrombocytopenic purpura (TTP).

OBJECTIVE

We sought to report AKI features and outcomes in patients with TTP.

METHODS

We conducted a retrospective study of 92 patients with TTP assessed by low ADAMTS13 activity (< 10%) between 2001 and 2013. A logistic regression identified variables independently associated with AKI.

RESULTS

Among the 92 patients, 54 (58.7%) presented with AKI, including 25 (46.3%) with stage 3 AKI. Fourteen (27.4%) patients had a nephrotic-range proteinuria and 21 (45.6%) had hemoglobinuria. Hematuria and leucocyturia were detected in 19 (41.3%) and 16 patients (36.4%), respectively. Renal replacement therapy (RRT) was required in 14 patients (25.9%). Six months after TTP remission, RRT-free patients had median (IQR) MDRD (Modification of Diet in Renal Disease formula estimating the glomerular filtration rate) of 93 mL min(-1) per 1.73 m(2) (68.8-110) and three patients required long-term dialysis. Mild or moderate chronic renal disease occurred in 23/54 (42.6%) AKI patients. By multivariate analysis, serum level of complement component 3 at admission was the only factor independently associated with AKI (OR per 0.25 unit decrease of C3, 0.85; CI, 1.82-8.33; P = 0.001).

CONCLUSIONS

In patients with TTP, AKI is present in more than half the patients, and half of those will have lasting renal effects. Further studies to better understand the pathophysiology of renal involvement in patients with TTP and to identify a subset of patients with TTP syndrome overlapping HUS are warranted.

Resistive Index or color-Doppler semi-quantitative evaluation of renal perfusion by inexperienced physicians: results of a pilot study

BACKGROUND

Doppler-based renal resistive index (RI) calculation may help in the early detection of acute kidney injury (AKI). Its feasibility and reproducibility by inexperienced operators remain unknown. The main objective of this study was to compare performances of junior and senior operators in assessing renal perfusion using both the semiquantitative color-Doppler scale and RI calculation.

METHODS

Prospective cohort study performed in 3 ICUs. Inexperienced juniors physicians attended a half-day course on renal perfusion assessment using RI calculation and color-Doppler (from 0, absence of renal perfusion; to 3, renal vessels identifiable in the entire field of view). Junior and senior operators used both methods in 69 mechanically ventilated patients, in blind fashion.

RESULTS

Failure to obtain RI occurred for a junior operator in a single patient. RI and color-Doppler semi-quantitative values obtained by operators were correlated (r²=0.64 and r²=0.61, respectively). Systematic bias across operators as assessed using Bland-Altman plots was negligible (-0.001 and -0.29, respectively), although precision was limited (95% confidence intervals, +0.105 to -0.107 and +0.98 to -1.04, respectively). RI calculation and semi-quantitative assessment performed well for diagnosing persistent AKI (area under the receiver-operating characteristic curve, 0.84 [95% confidence interval, 0.73-0.97] and 0.87 [0.77-0.97], respectively).

CONCLUSION

A brief course on renal Doppler allowed inexperienced operators to assess effectively renal perfusion with a good reliability when compared to senior operators. In addition, our results suggest the good diagnostic performance of both Doppler-based RI and semi-quantitative renal perfusion assessment in predicting short-term renal dysfunction reversibility.

Modeling of ray paths of head waves on irregular interfaces in TOFD inspection for NDE

The TOFD (Time of Flight Diffraction) technique is a classical ultrasonic inspection method used in ultrasonic non-destructive evaluation (NDE). This inspection technique is based on an arrangement of two probes of opposite beam directions and allows a precise positioning and a quantitative evaluation of the size of cracks contained in the inspected material thanks to their edges diffraction echoes. Among the typical phenomena arising for such an arrangement, head waves, which propagate along the specimen surface and are chronologically the first waves reaching the receiver, are notably observed. Head wave propagation on planar surfaces in TOFD configurations is well known. However, realistic inspection configurations often involve components with irregular surfaces, like steel excavated specimens. Surface irregularity is responsible for numerous effects on the scattering of bulk waves, causing the melting of surface and bulk mechanisms in the head wave propagation. In order to extend the classical ray approach on these complex cases, a generic algorithm of ray tracing between interface points (GIRT) has been designed. With respect to time of flight minimization (i.e. the Generalized Fermat's Principle), ray paths can be computed by GIRT for different natures of waves scattered by the complex surfaces or by flaws. The head wave fronts computed by GIRT are notably in good agreement with FEM simulated results. This algorithm, based on pure kinematic analysis of waves propagation, represents a first step in the future development of a complete ray theory for head waves simulation on irregular interfaces.

Acute respiratory failure in neutropenic patients is associated with a high post-ICU mortality

BACKGROUND

Few studies have evaluated outcomes of neutropenic patients admitted to the ICU at the onset of acute respiratory failure (ARF). The main objective of this study was to describe outcomes and to identify early predictors of hospital mortality in critically ill cancer patients with ARF during chemotherapy-induced neutropenia.

METHODS

Retrospective analysis of prospectively collected data extracted from two recent prospective multicentre studies. We included neutropenic adults admitted to the ICU for ARF.

RESULTS

Of the 123 study patients, 107 patients (87%) had haematological malignancies; 78 (64%) were male, median age was 57 years (44-62), and median LOD score at ICU admission was 6 (4-9). ICU and hospital mortality rates were 42% and 77%, respectively. Endotracheal mechanical ventilation was an independent risk factor for hospital mortality (odds ratio [OR], 7.73; 95% confidence interval [95%CI], 2.52-23.69); two factors independently protected from hospital mortality, namely, ICU admission for ARF during neutropenia recovery (OR, 0.23; 95%CI, 0.07-0.73) and steroid therapy before ICU admission (OR, 0.35; 95%CI, 0.11-0.95).

CONCLUSION

Our study demonstrates a meaningful ICU survival in the studied population and identified factors associated with ICU and hospital mortality. Further work is needed to address the reasons for the high post-ICU mortality rate after ARF.

[Therapeutic of respiratory manifestations at the early phase of acute myeloid leukaemia]

The effective management of the respiratory manifestations at the early phase of acute myeloid hemopathies, especially acute myeloid leukaemia, frequently requires a close collaboration between hematologists, pulmonologists and intensivists. Dominated by infectious etiologies, there are however "specific" disease entities that should not be neglected in the diagnostic and therapeutic approach. These include lung leukostasis, leukemic lung infiltration, the cell lysis pneumopathy and the secondary alveolar proteinosis. These were the subject of a review in the Revue des Maladies Respiratoires published in 2010. We wished to review the management of these clinical situations, the severity of which mean patients frequently require intensive care unit admission. We are only able to make proposals for management here as there is little consensus, except in the metabolic care of tumour lysis syndrome. These data must therefore be reinterpreted regularly as new publications become available.

Expression and lysosomal targeting of CLN7, a major facilitator superfamily transporter associated with variant late-infantile neuronal ceroid lipofuscinosis

Neuronal ceroid lipofuscinoses (NCLs) constitute a group of progressive neurodegenerative disorders resulting from mutations in at least eight different genes. Mutations in the most recently identified NCL gene, MFSD8/CLN7, underlie a variant of late-infantile NCL (vLINCL). The MFSD8/CLN7 gene encodes a polytopic protein with unknown function, which shares homology with ion-coupled membrane transporters. In this study, we confirmed the lysosomal localization of the native CLN7 protein. This localization of CLN7 is not impaired by the presence of pathogenic missense mutations or after genetic ablation of the N-glycans. Expression of chimeric and full-length constructs showed that lysosomal targeting of CLN7 is mainly determined by an N-terminal dileucine motif, which specifically binds to the heterotetrameric adaptor AP-1 in vitro. We also show that CLN7 mRNA is more abundant in neurons than astrocytes and microglia, and that it is expressed throughout rat brain, with increased levels in the granular layer of cerebellum and hippocampal pyramidal cells. Interestingly, this cellular and regional distribution is in good agreement with the autofluorescent lysosomal storage and cell loss patterns found in brains from CLN7-defective patients. Overall, these data highlight lysosomes as the primary site of action for CLN7, and suggest that the pathophysiology underpinning CLN7-associated vLINCL is a cell-autonomous process.

Procedure volume is one determinant of centre effect in mechanically ventilated patients

Survival rates vary significantly between intensive care units, most notably in patients requiring mechanical ventilation (MV). The present study sought to estimate the effect of hospital MV volume on hospital mortality. We included 179,197 consecutive patients who received mechanical ventilation in 294 hospitals. Multivariate logistic regression models with random intercepts were used to estimate the effect of annual MV volume in each hospital, adjusting for differences in severity of illness and case mix. Median annual MV volume was 162 patients (interquartile range 99-282). Hospital mortality in MV patients was 31.4% overall, 40.8% in the lowest annual volume quartile and 28.2% in the highest quartile. After adjustment for severity of illness, age, diagnosis and organ failure, higher MV volume was associated with significantly lower hospital mortality among MV patients (OR 0.9985 per 10 additional patients, 95% CI 0.9978-0.9992; p = 0.0001). A significant centre effect on hospital mortality persisted after adjustment for volume effect (p < 0.0001). Our study demonstrated higher hospital MV volume to be independently associated with increased survival among MV patients. Significant differences in outcomes persisted between centres after adjustment for hospital MV volume, supporting a role for other significant determinants of the centre effect.

Maternal serotonin influences cardiac function in adult offspring

Using the Tph1-invalidated mouse line, in which blood is depleted in serotonin (5-hydroxytryptamine, 5-HT), we have demonstrated previously that maternal 5-HT is required for normal embryonic development. Here, we address the issue of the influence of the maternal 5-HT concentration on the cardiac function of the offspring as adults. We investigated the cardiac phenotype of Tph1-invalidated mice born to Tph1 heterozygous and null mothers. Functionally, all mutants display a significant decrease of cardiac contractility, indicative of impaired left ventricular function. They exhibit progressive dilated cardiomyopathy and are unable to adapt appropriately to a pharmacological stress. Moreover, we show that the cardiopathy is more severe in adult Tph1(-/-) mice born to homozygous mothers than to heterozygous mothers. Importantly, the severity of the cardiac phenotype is inversely correlated with the plasma 5-HT concentration but not the whole-blood 5-HT concentration. Thus, plasma 5-HT concentration may be a useful index of heart failure. These findings show that cardiac function, through the plasma 5-HT concentration, is influenced by the maternal serotonergic status.

Immunolabelling of the 5-HT3B receptor subunit in the central and peripheral nervous systems in rodents

The 5-HT(3) receptor is a member of the superfamily of neurotransmitter-gated ion channels involved in fast synaptic signalling and in modulation of neurotransmitter release. As for many other channel receptors, the electrophysiological properties and the functions of the 5-HT(3) receptor are determined by subunit composition of the pentameric channel. Because in situ hybridization did not allow the detection of mRNA encoding the 5-HT(3B) subunit in the rodent central nervous system, or in nearly half of the neurons expressing the 5-HT(3A) subunit in peripheral ganglia, it has been suggested that subunit composition could define at least two 5-HT(3) receptor-expressing neuronal populations. In order to challenge this hypothesis, we have developed polyclonal antibodies directed against a portion of the second intracytoplasmic loop of the mouse 5-HT(3B) subunit. Immunohistochemical analysis in the mouse and the rat revealed that immunolabelling was most prominent in peripheral ganglia, particularly in trigeminal ganglia (TG). In rats, transection or ligature of the infraorbital nerve resulted in a pronounced accumulation of immunoreactive material at the proximal side of the lesioned nerve, and an up-regulation of both subunits in 5-HT(3) receptor-expressing TG neurons. Surprisingly, nearly 100% of neurons expressing 5-HT(3A) subunits were also labelled by anti-5-HT(3B) antibodies. We also detected 5-HT(3B) immunoreactivity in the rat hippocampal CA1 layer and in scattered cortical neurons, indicating that detection of 5-HT(3) subunit mRNA by in situ hybridization might not provide really complete mapping of heteromeric 5-HT(3A/B) vs. homomeric 5-HT(3A) receptors in the peripheral and central nervous systems in rodents.

Combined hyperlipidemia/hyperalphalipoproteinemia associated with premature spontaneous atherosclerosis in mice lacking hepatic lipase and low density lipoprotein receptor

BACKGROUND AND METHODS

Hepatic lipase (HL) is an enzyme which hydrolyzes triglycerides from plasma lipoproteins and thus takes part in the metabolism of triglyceride-rich lipoprotein remnants and high density lipoproteins. The search described here concentrated on the description of the double invalidation of the HL and LDL receptor genes in mice in order to better understand the possible role of HL in combined hyperlipidemia/hyperalphalipoproteinemia and development of atherosclerosis.

RESULTS

We show here that mice lacking both endogenous HL and LDL receptor (HL-/-:LDLR-/-) dramatically increased their plasma triglyceride-rich lipoproteins and their remnants as a consequence of reduced liver uptake. This result is strenghthened by the fact that HL-/-:LDLR-/- were found to overexpress LRP, LSR, and apoE genes. Interestingly, HL-/-:LDLR-/- mice showed premature spontaneous atherosclerosis and aortic lesions from 1-year-old animals were two-fold larger than those of LDLR-/- single mutants. We confirmed that HL-/- and wild-type mice did not develop atherosclerosis lesion even 1 year after birth.

CONCLUSIONS

Analysis of this double HL-LDLR knockout mouse model provides in vivo evidence that HL has a major role in the clearance of TRL remnants when LDLR is deficient and in the reduction of the development of atherosclerosis.

Role of the C-terminal di-leucine motif of 5-HT1A and 5-HT1B serotonin receptors in plasma membrane targeting

The 5-HT1A and 5-HT1B serotonin receptors exhibit different subcellular localizations in neurons. Evidence has been reported that the C-terminal domain is involved in the somato-dendritic and axonal targeting of 5-HT1AR and 5-HT1BR, respectively. Here we analyzed the consequences of the mutation of a di-leucine motif and palmitoylated cysteines within this domain. Replacement of I414-I415 by a di-alanine in 5-HT1AR led to endoplasmic reticulum (ER) sequestration of the corresponding mutant expressed in cell lines as well as in hippocampal neurons in culture. Furthermore, di-leucine-mutated receptors were unable to bind 5-HT1A agonists and presented a major deficit in their glycosylation state, suggesting that they are misfolded. By contrast, mutation of the di-leucine motif in the C-terminal domain of 5-HT1BR had no major consequence on its subcellular targeting. However, in the case of the 1ActB chimera (substitution of the C-terminal domain of the 5-HT1BR into 5-HT1AR), this mutation was also found to cause sequestration within the ER. Replacement of palmitoylated cysteines by serines had no consequence on either receptor type. These data indicate that the di-leucine motif of the 5-HT1AR and 5-HT1BR tails is implicated in proper folding of these receptors, which is necessary for their ER export.

Outcomes of critically ill patients with lung cancer

16001

Background: Recent advances in oncology and critical care have resulted in improved survival in critically ill cancer patients. An appraisal of the prognosis of critically ill patients with lung cancer is timely. Methods: The aim of this study was to evaluate the outcomes and prognostic factors of critically ill cancer patients with lung cancer. From 2000 to 2005, patients with either small-cell (SCLC) or non-small-cell lung cancer (NSCLC) admitted at two intensive care units (ICU) in Brazil and France were included. Patients with postoperative care, ICU stay <24 h and readmissions were excluded. Demographics, clinical, cancer related and outcome variables were collected. Hospital mortality was the outcome variable of interest. Variables selected in the univariate analysis (p < 0.25) and those considered clinically relevant were entered in a multivariable logistic regression analysis [results were expressed as odds-ratios (OR), 95% confidence interval (CI)]. Results: A total of 132 patients were studied (INCA = 87, St Louis Hospital = 45). Their mean age was 61 ± 10 years and 73% were males. Twenty-five (19%) had SCLC and 107 (81%), NSCLC. The SAPS II score was 48 ± 21 points. The main reasons for ICU admission were severe sepsis (45%) and acute respiratory failure (33%). During ICU stay, 96 (73%) patients received mechanical ventilation, 76 (58%) vasopressors and 11 (8%) dialysis; 15 (11%) patients were treated with chemotherapy and 6 (5%), radiation therapy. Thirty-eight (29%) patients had end-of-life decisions. ICU and hospital mortality were 43% and 60%, respectively. Multivariable analysis identified three independent determinants of hospital mortality: airway obstruction/infiltration by cancer [OR = 2.87 (1.34–8.13), p < 0.001], number of organ failures [OR = 1.91 (1.01–2.74), p = 0.047] and performance status 3–4 before admission [OR = 2.90 (0.94–8.95), p = 0.065]. Conclusions: Improved survival in overall ICU cancer patients extends to patients with lung cancer, including those needing mechanical ventilation. Interestingly, the characteristics of the cancer are not associated with the outcome and should not be the grounds for the ICU decision making. Mortality is increased with the number of organ dysfunctions, in particular when respiratory failure is due to cancer progression.

No significant financial relationships to disclose.

Mice lacking brain/kidney phosphate-activated glutaminase have impaired glutamatergic synaptic transmission, altered breathing, disorganized goal-directed behavior and die shortly after birth

Neurotransmitter glutamate has been thought to derive mainly from glutamine via the action of glutaminase type 1 (GLS1). To address the importance of this pathway in glutamatergic transmission, we knocked out GLS1 in mice. The insertion of a STOP cassette by homologous recombination produced a null allele that blocked transcription, encoded no immunoreactive protein, and abolished GLS1 enzymatic activity. Null mutants were slightly smaller, were deficient in goal-directed behavior, hypoventilated, and died in the first postnatal day. No gross or microscopic defects were detected in peripheral organs or in the CNS. In cultured neurons from the null mutants, miniature EPSC amplitude and duration were normal; however, the amplitude of evoked EPSCs decayed more rapidly with sustained 10 Hz stimulation, consistent with an observed reduction in depolarization-evoked glutamate release. Because of this activity-dependent impairment in glutamatergic transmission, we surmised that respiratory networks, which require temporal summation of synaptic input, would be particularly affected. We found that the amplitude of inspirations was decreased in vivo, chemosensitivity to CO2 was severely altered, and the frequency of pacemaker activity recorded in the respiratory generator in the pre-Bötzinger complex, a glutamatergic brainstem network that can be isolated in vitro, was increased. Our results show that although alternate pathways to GLS1 glutamate synthesis support baseline glutamatergic transmission, the GLS1 pathway is essential for maintaining the function of active synapses, and thus the mutation is associated with impaired respiratory function, abnormal goal-directed behavior, and neonatal demise.

Constitutive activation drives compartment-selective endocytosis and axonal targeting of type 1 cannabinoid receptors

The type 1 cannabinoid receptor (CB1R) is one of the most abundant G-protein-coupled receptors (GPCRs) in the brain, predominantly localized to axons of GABAergic neurons. Like several other neuronal GPCRs, CB1R displays significant in vitro constitutive activity (i.e., spontaneous activation in the absence of ligand). However, a clear biological role for constitutive GPCR activity is still lacking. This question was addressed by studying the consequences of constitutive activation on the intracellular trafficking of endogenous or transfected CB1Rs in cultured hippocampal neurons using optical and electron microscopy. We found that constitutive activity results in a permanent cycle of endocytosis and recycling, which is restricted to the somatodendritic compartment. Thus, CB1Rs are continuously removed by endocytosis from the plasma membrane in the somatodendritic compartment but not in axons, where CB1Rs accumulate on surface. Blocking constitutive activity by short-term incubation with inverse agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide (AM281) results in sequestration of recycled CB1Rs on the somatodendritic plasma membrane. Long-term inhibition of endocytosis by cotransfection of dominant-negative proteins results in impaired axonal polarization of surface-bound CB1Rs. Kinetic analysis shows that the majority of newly synthesized CB1Rs arrive first to the somatodendritic plasma membrane, from where they are rapidly removed by AM281-sensitive constitutive endocytosis before being delivered to axons. Thus, constitutive-activity driven somatodendritic endocytosis is required for the proper axonal targeting of CB1R, representing a novel, conformation-dependent targeting mechanism for axonal GPCRs.

Identification of nutritionally adequate mixtures of vegetable oils by linear programming

OBJECTIVE

To determine the types and proportions of vegetable oils to recommend for a healthy diet.

METHODS

Optimal vegetable oil combinations were designed, using linear programming and, as decision variables, nine single oils and 29 basic food items. 'Oil models' were run to determine whether reasonable amounts of individuals oils or oil mixtures satisfied a set of constraints on essential fatty acids and vitamin E. 'Meal models' were run to test whether selected mixtures could be used as the sole source of added fat in a meal that met micronutrient and macronutrient recommendations.

RESULTS

The cheapest mixture (0.97 euro L(-1)) that solved the oil models contained 81% rapeseed and 19% sunflower oils. About 10-15 g of this mixture, alone or with olive, soya bean, wheat germ or walnut oils, also solved the meal models. Mixtures that contained a high proportion (>or=50%) of the tasty olive and walnut oils also solved the models but were more expensive (4.9 euro L(-1) and 8.5 euro L(-1), respectively).

CONCLUSIONS

The consumption of a mixture composed of rapeseed and sunflower oils in a 4 : 1 proportion is an inexpensive and simple way to meet current dietary recommendations for essential fatty acids and vitamin E, favouring overall dietary nutrient adequacy.