Post-mortem radiology in fetal and neonatal death: the diagnostic value of post-mortem MRI versus autopsy regarding non-cardiac thoracic and abdominal abnormalities.

AIM: To compare the diagnostic value and accuracy of post-mortem magnetic resonance imaging (PMMRI) and autopsy for non-cardiac thoracic and abdominal abnormalities in fetal death. MATERIALS AND METHODS: This single-institution retrospective study included all consecutive cases of fetal and perinatal death between January 2015 and December 2021 for which PMMRI followed by autopsy was conducted. These cases comprised fetuses at >18 weeks of gestation and preterm and term neonates who lived for <24 h. All PMMRI and autopsy reports were re-assessed and scored for seven non-cardiac thoracic and 52 abdominal abnormalities, and concordance between autopsy and PMMRI findings was determined as the primary outcome. RESULTS: Eighty cases were included in this study. Fetal loss was caused by termination of pregnancy in 80% of cases. Further, the mean gestational age was 166 days (23 weeks and 5 days, range 126-283 days). The concordance between PMMRI and autopsy for non-cardiac thoracic and abdominal abnormalities was 83.1% (95% confidence interval [CI] 71.3-83.3) and 76.3% (95% CI 65.8-84.2%), respectively, with a substantial and moderate strength of agreement (Cohen's kappa = 0.63 and 0.51 respectively). CONCLUSION: PMMRI exhibited good overall diagnostic value for non-cardiac thoracic and abdominal abnormalities, specifically large structural abnormalities. PMMRI may offer parents and physicians a valuable addition to autopsy for the detection of non-cardiac thoracic and abdominal abnormalities, or even an alternative option when parents do not consent to autopsy.

[Cellular immunotherapy at the University Hospital of Liege : advances, challenges and prospects]. / Immunothérapie cellulaire au CHU de Liège : avancées, défis et perspectives.

Cellular immunotherapy consists in using the cells of the immune system as a therapeutic weapon. In this constantly evolving field, the therapeutic strategies developed at the University Hospital of Liege are hematopoietic stem cell transplantation, mesenchymal stromal cells and targeted therapy with CAR-T cells (Chimeric Antigen Receptor T cells). The first two modalities represent a form of non-targeted cell therapy that has been developed over the past decades. While hematopoietic stem cell transplantation is established as the reference treatment for many hematological diseases, mesenchymal stromal cells are still under investigation in various pathologies (notably Crohn's disease, organ transplantation, COVID-19 and pulmonary fibrosis). By contrast, CAR-T cells represent a recently developed and extremely promising targeted immunotherapy. This therapeutic approach has already revolutionized the treatment of B-cell lymphopathies, and has the potential to do the same for many other diseases in the near future.

L'immunothérapie cellulaire consiste en l'utilisation de cellules du système immunitaire comme arme thérapeutique. Dans ce domaine en évolution constante, les stratégies thérapeutiques développées au CHU de Liège sont la greffe de cellules souches hématopoïétiques, les cellules stromales mésenchymateuses et la thérapie ciblée par cellules CAR-T («Chimeric Antigen Receptor T cells¼). Les deux premières approches représentent une forme de thérapie cellulaire non ciblée, développées depuis de nombreuses années. Si la greffe de cellules souches hématopoïétiques est établie comme le traitement de référence de nombreuses hémopathies, les cellules stromales mésenchymateuses sont, quant à elles, toujours à l'étude dans diverses pathologies (notamment maladie de Crohn, transplantation d'organes, COVID-19 et fibrose pulmonaire). À l'opposé, les cellules CAR-T représentent une immunothérapie ciblée, développée récemment et extrêmement prometteuse. Cette modalité thérapeutique a déjà révolutionné le traitement des lymphopathies B, et elle possède le potentiel d'en faire de même pour de nombreuses autres pathologies dans un avenir proche.

Randomized controlled trial of a group intervention combining self-hypnosis and self-care: secondary results on self-esteem, emotional distress and regulation, and mindfulness in post-treatment cancer patients.

PURPOSE: Cancer patients often report low self-esteem and high emotional distress. Two factors seem particularly linked to these symptoms: emotion regulation strategies and mindfulness. The interest of hypnosis and self-care to relieve these symptoms is not well documented. Our randomized controlled trial aimed at assessing the effect of a group intervention combining self-hypnosis and self-care on self-esteem, emotional distress, emotion regulation, and mindfulness abilities of post-treatment cancer patients, as well as investigating the links between these variables. METHODS: One hundred and four patients who had suffered from cancer were randomized into the intervention group (N = 52) and the wait-list control group (N = 52). They had to answer questionnaires before (T1) and after the intervention (T2). Nine men were excluded from the analyses, leading to a final sample of 95 women with cancer. Group-by-time changes were assessed with MANOVA, and associations with self-esteem and emotional distress were investigated with hierarchical linear regression models. RESULTS: Participants in the intervention group (mean age = 51.65; SD = 12.54) reported better self-esteem, lower emotional distress, a decreased use of maladaptive emotion regulation strategies, and more mindfulness abilities after the intervention, compared to the WLCG. This increase in mindfulness explained 33% of the improvement of self-esteem and 41.6% of the decrease of emotional distress in the intervention group. Self-esteem and emotional distress also predicted each other. CONCLUSION: Our study showed the efficacy of our hypnosis-based intervention to improve all the investigated variables. Mindfulness predicted the improvement of self-esteem and emotional distress. The primary impact of our intervention on mindfulness abilities seems to explain, at least in part, its efficacy. Registration: ClinicalTrials.gov (NCT03144154). Retrospectively registered on the 1st of May, 2017.

Efficacy and safety of aerosolized intra-tracheal dornase alfa administration in patients with SARS-CoV-2-induced acute respiratory distress syndrome (ARDS): a structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) may trigger severe pneumonia in coronavirus disease of 2019 (COVID-19) patients through release of damage-associated molecular patterns (DAMPs) and recruitment of neutrophils in the lungs. Activated neutrophils induce inflammation and severe alveolar injury by releasing neutrophil extracellular traps (NETs). The backbones of many DAMPs and NETs are made of extracellular, cell-free DNA decorated with highly toxic compounds such as elastase, myeloperoxidase and citrullinated histones. Dornase alfa is a FDA-approved recombinant human DNAse 1 for the treatment of cystic fibrosis, which cleaves extracellular DNA and may break up cell-free DNA, loosening sticky mucus in the distal airways and reducing NETs-induced toxicity on alveolar pneumocytes. The COVIDornase trial intends to define the impact of aerosolized intra-tracheal dornase alfa administration on the severity and progression of acute respiratory distress syndrome (ARDS) in COVID-19 patients. This drug might make lung mucus thinner and looser, promoting improved clearance of secretions and reduce extracellular double-stranded DNA-induced hyperinflammation in alveoli, preventing further damage to the lungs. TRIAL DESIGN: COVIDornase is a prospective, randomized, controlled, 2-arm (1:1 ratio), multicentric, open-label clinical trial. PARTICIPANTS: The study will recruit mechanically ventilated patients hospitalized in the intensive care unit (ICU) in the recruiting centres (at the time of writing: The Rothschild foundation hospital in Paris, the Strasbourg university hospitals, and Metz-Thionville hospital) who have been diagnosed with COVID-19 and meet ARDS criteria. INCLUSION CRITERIA: - Adult patient (age ≥ 18 years old); - Hospitalized in ICU; - With severe COVID-19 pneumonia and ARDS according to Berlin criteria (PaO2/FiO2 < 300 and PEEP > 5 cmH2O); - Intubated for less than 8 days; - With an anticipated duration of mechanical ventilation > 48 hours; - Carrier of an arterial catheter; - For whom 4 PaO2/FiO2 values over the preceding 24 hours are available; NON-INCLUSION CRITERIA: - Known hypersensitivity to dornase alfa or any of its excipients; - Pregnant or breastfeeding status; - Patient under legal protection. INTERVENTION AND COMPARATOR: Intervention 1, Study group Dornase alfa (Pulmozyme®, Roche, Switzerland) will be administered by aerosol, at a dose of 2500 IU twice daily, 12 hours apart, for 7 consecutive days, using a vibrating mesh nebulizer (Aerogen Solo®, Aerogen, Ireland). The remainder of the management will be performed in accordance with good clinical practice, including mechanical ventilation (protective ventilation, PEEP > 5 cmH2O, tracheal balloon pressure check every 4 hours or automatic device, 30° head of the bed elevation, tidal volume 6-8mL/kg, plateau pressure < 30 cmH2O), neuromuscular blockers if necessary, prone position if PaO2/FiO2 < 150, early enteral nutrition, glycemic control and a sedation protocol based on the RASS score. Intervention 2, Comparator Patients will receive usual care in accordance with good practice (as detailed above), without aerosols. MAIN OUTCOMES: The primary outcome is the occurrence of at least one grade improvement between D0 (inclusion) and D7 in the ARDS scale severity (Berlin criteria). For instance from "severe" to "moderate" or from "moderate" to "mild". RANDOMISATION: All consecutive patients meeting the inclusion criteria will be randomised 1:1 using an eCRF-based, computer-generated randomisation table, either to the dornase alfa arm or to the control arm. An interim analysis will be performed after inclusion of 20 patients. Inclusions may be stopped at the interim analysis per data safety and monitoring board (DSMB) advice, if statistical analyses conclude on the futility or efficacy of the intervention or by other DSMB decision. BLINDING (MASKING): The participants and caregivers will not be blinded to study group assignment. Those assessing the outcomes will be blinded to study group assignment. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): Fifty patients will be randomized to each group, 100 patients in total. TRIAL STATUS: Protocol version number 2, April 29th, 2020. Recruitment is ongoing. The trial started recruitment on the 21st April 2020. We estimate recruitment will finish August 21st 2020. TRIAL REGISTRATION: The trial was registered in ClinicalTrials.gov on 21 April 2020, updated on 8 May 2020. Trial registration number is NCT04355364. FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated. This Letter serves as a summary of the key elements of the full protocol.

Discrete Helmholtz model: a single layer of correlated counter-ions. Metal oxides and silica interfaces, ion-exchange and biological membranes.

The mechanism by which interfaces in solution can be polarised depends on the nature of the charge carriers. In the case of a conductor, the charge carriers are electrons and the polarisation is homogeneous in the plane of the electrode. In the case of an insulator covered by ionic moieties, the polarisation is inhomogeneous and discrete in the plane of the interface. Despite these fundamental differences, these systems are usually treated in the same theoretical framework that relies on the Poisson-Boltzmann equation for the solution side. In this perspective, we show that interfaces polarised by discrete charge distributions are rather ubiquitous and that their associated potential drop significantly differs from those of conductor-electrolyte interfaces. We show that these configurations, spanning liquid-liquid interfaces, charged silica-water interfaces, metal oxide interfaces, supercapacitors, ion-exchange membranes and even biological membranes can be uniformly treated under a common "Discrete Helmholtz" model where the discrete charges are compensated by a single layer of correlated counter-ions, thereby generating a sharp potential drop at the interface.

How to polarise an interface with ions: the discrete Helmholtz model.

The distribution of electrolytes in an electric field usually relies on theories based on the Poisson-Boltzmann formalism. These models predict that, in the case of a metallic electrode, ionic charges screen the electrode potential, leading to concentration-dependent ion distributions. This theoretical framework was first applied at solid-liquid interfaces and then transposed to soft interfaces. However, in this latter case, the potential in which the electrolytes evolve is not homogeneous, which is less amenable to a mean-field description. In this report, we show that at polarised soft interfaces the potential difference takes place between two closely interacting ionic monolayers. In this configuration, ions of opposite charges directly neutralise each other leading to an absence of diffuse layers and charge screening by surrounding ions. Thus, independently of the electrolyte concentrations, the surface charge density is a linear function of the potential difference, which results in a constant capacitance.

Two dimensional diffusion-controlled triplet-triplet annihilation kinetics.

Diffusion controlled chemical reactions are usually observed in three dimensional media. In contrast, planar bimolecular reactions taking place between reagents adsorbed at a soft interface are two-dimensional and therefore cannot be studied within the same formalism. Indeed, soft interfaces allow the adsorbed species to freely diffuse in a liquid-like manner. Here, we present the first experimental observation of a diffusion-controlled reaction in an environment that is planar at the ångström scale. By means of time-resolved surface second harmonic generation, an inherently surface sensitive technique, we observed that the kinetics of the diffusion of the reagents in the plane decreases as the surface concentration of adsorbed species increases. This is of course not the case for bulk reactions where the rates always increase with the reactant concentration. Such changes in the kinetics regime were rationalised as the evolution from a regular 2D free diffusion regime to a geometry-controlled scheme.

Efficacy of a hypnosis-based intervention to improve well-being during cancer: a comparison between prostate and breast cancer patients.

BACKGROUND: Prostate and breast cancer can have a lot of negative consequences such as fatigue, sleep difficulties and emotional distress, which decrease quality of life. Group interventions showed benefits to emotional distress and fatigue, but most of these studies focus on breast cancer patients. However, it is important to test if an effective intervention for breast cancer patients could also have benefits for prostate cancer patients. METHODS: Our controlled study aimed to compare the efficacy of a self-hypnosis/self-care group intervention to improve emotional distress, sleep difficulties, fatigue and quality of life of breast and prostate cancer patients. 25 men with prostate cancer and 68 women with breast cancer participated and were evaluated before (T0) and after (T1) the intervention. RESULTS: After the intervention, the breast cancer group showed positive effects for anxiety, depression, fatigue, sleep difficulties, and global health status, whereas there was no effect in the prostate cancer group. We showed that women suffered from higher difficulties prior to the intervention and that their oncological treatments were different in comparison to men. CONCLUSION: The differences in the efficacy of the intervention could be explained by the baseline differences. As men in our sample reported few distress, fatigue or sleep problems, it is likely that they did not improve on these dimensions. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT02569294 and NCT03423927 ). Retrospectively registered in October 2015 and February 2018 respectively.

[Oxynorm® instant versus Tradonal® odis as level 2 analgesic in an emergency service : a monocentric double blind randomized non-inferiority study]. / Utilisation de l'oxynorm® instant versus tradonal® odis, antalgiques de Palier 2 dans un service d'urgence : une étude monocentrique comparative, randomisée en double aveugle, de non-infériorité.

Pain is one of the most common reasons for consultation in the ER. As far as class II analgesics are concerned, tramadol is most usually used. According to some data from the literature, it would seem that oxycodone and tramadol are equivalent in terms of analgesia. We have tried to prove that oxycodone (Oxynorm® instant) is not less effective than tramadol (Tradonal® odis) in an emergency unit. This is a prospective, monocentric, randomized study carried out amongst ambulatory patients. Those included in the study were given 1 g of paracetamol and a weight-ajusted dose of either tramadol or oxycodone. Every 30 minutes, a simple numerical scale (NS) was established and the clinical parameters were checked. We studied a total of 121 patients divided into 2 groups. There is an average difference of -1.47 between the average ?NS of the oxycodone group and the average ?NS of the tramadol group, with a confidence interval of 95 % (-9.42 - 6.48). The confidence interval does not cross the -10 line considered as the acceptable loss of efficiency, which allows us to conclude that oxycodone is not inferior to tramadol. As far as the adverse effects studied are concerned, there is no significant link between the treatment and the appearance of any side effect.

La douleur est l'un des motifs de consultation le plus fréquent en salle d'urgence. Au sein du palier 2, l'utilisation du tramadol est la plus fréquente malgré ses effets secondaires fréquents. Des données de la littérature suggèrent une équivalence en termes d'analgésie entre l'oxycodone et le tramadol. Nous avons tenté de montrer la non-infériorité de l'oxycodone (Oxynorm® instant) en comparaison au tramadol (Tradonal® odis) dans un service d'urgence. Cette étude est prospective monocentrique randomisée menée au sein d'une population de patients désignés comme ambulants. Les patients inclus recevaient 1 g de paracétamol et une dose de tramadol ou d'oxycodone ajustée au poids corporel. Une échelle numérique simple (EN), outil d'évaluation de la douleur, a été réalisée toutes les 30 minutes, accompagnée par la prise des paramètres cliniques. Nous avons étudié un total de 121 patients. La moyenne de la différence entre la moyenne de ?EN du groupe oxycodone et la moyenne de ?EN du groupe tramadol est de -1,47 (IC à 95 % -9,42 ­ 6,48). L'intervalle de confiance ne vient pas croiser la valeur de -10 fixée comme la perte d'efficacité acceptable, ce qui nous permet de conclure à la non-infériorité de l'oxycodone par rapport au tramadol. Il n'y a pas d'association significative entre le traitement et le fait de présenter des effets secondaires.

Electrovariable gold nanoparticle films at liquid-liquid interfaces: from redox electrocatalysis to Marangoni-shutters.

Control over the physical properties of nanoparticle assemblies at a liquid-liquid interface is a key technological advancement to realize the dream of smart electrovariable nanosystems. Electrified interfaces, such as the interface between two immiscible electrolytes solutions (ITIES), are almost an ideal platform for realizing this dream. Here, we show that the Galvani potential difference across soft interfaces can be effectively used to manipulate: (i) the reactivity of gold nanoparticle assemblies through varying the Fermi level (both chemically and electrochemically); (ii) the location distribution of the nanoparticles at the liquid-liquid interface. In the first case, in addition to our previous studies on electron transfer reactions (ET) across the ITIES, we used intensity modulated photocurrent spectroscopy (IMPS) to study the kinetics of photo-induced electrochemical reactions at the ITIES. As expected, the direct adsorption of gold nanoparticles at the interface modifies the kinetics of the ET reaction (so-called, interfacial redox electrocatalysis), however it did not lead to an increased photocurrent by "plasmonic enhancement". Rather, we found that the product separation depends on double layer effects while the product recombination is controlled by the Galvani potential difference between the two phases. In the second case, we demonstrated that polarizing the ITIES caused migration of gold nanoparticles from the middle region of the cell to its periphery. We called such systems "Marangoni-type shutters". This type of electrovariable plasmonic system did not experience diffusion limitation in terms of the adsorption/desorption of nanoparticles and the entire movement of nanoparticle assemblies happened almost instantly (within a second). It opens a fresh view on electrovariable plasmonics and presents new opportunities to create smart nanosystems at the ITIES driven with an electric field.

Photoproduction of Hydrogen by Decamethylruthenocene Combined with Electrochemical Recycling.

The photoinduced hydrogen evolution reaction (HER) by decamethylruthenocene, Cp2 *RuII (Cp*=C5 Me5 ), is reported. The use of a metallocene to photoproduce hydrogen is presented as an alternative strategy to reduce protons without involving an additional photosensitizer. The mechanism was investigated by (spectro)electrochemical and spectroscopic (UV/Vis and 1 H NMR) measurements. The photoactivated hydride involved was characterized spectroscopically and the resulting [Cp2 *RuIII ]+ species was electrochemically regenerated in situ on a fluorinated tin oxide electrode surface. A promising internal quantum yield of 25 % was obtained. Optimal experimental conditions- especially the use of weakly coordinating solvent and counterions-are discussed.

Review article: mesenchymal stromal cell therapy for inflammatory bowel diseases.

BACKGROUND: Inflammatory bowel diseases (IBD) are chronic relapsing diseases in which pro-inflammatory immune cells and cytokines induce intestinal tissue damage and disability. Mesenchymal stromal cells (MSCs) exert powerful immunomodulatory effects and stimulate tissue repair. AIM: To review the current data on mesenchymal stromal cell therapy in IBD. METHOD: We searched PubMed and 'ClinicalTrials.gov' databases using the terms 'mesenchymal stromal cells', 'mesenchymal stem cell transplantation', 'inflammatory bowel diseases', 'Crohn disease' and 'colitis, ulcerative'. Additional publications were identified from individual article reference lists. RESULTS: MSCs include inhibition of Th1/Th17 lymphocytes and recruitment of regulatory T lymphocytes, induction of antigen-presenting cells into a regulatory-like profile, and stimulation of epithelial cell differentiation and proliferation. More than 200 patients with refractory fistulas have been treated with local injections of MSCs, resulting in complete response in more than half, and in overall response in approximately two thirds of patients. In refractory luminal Crohn's disease, 49 cases of systemic MSC infusions have been reported, while trials with autologous MSCs resulted in mitigated responses, studies using allogeneic MSCs were promising, with around 60% of patients experiencing a response and around 40% achieving clinical remission. CONCLUSIONS: Mesenchymal stromal cells might represent a promising therapy for IBD, especially for Crohn's disease. There remain many unsolved questions concerning the optimal origin and source of mesenchymal stromal cells, dosage and modalities of administration. Moreover, mesenchymal stromal cells still need to prove their effectiveness compared with conventional treatments in randomised controlled trials.

Metastatic signet-ring cell carcinoma of unknown primary origin.

About 3-5% of metastatic cancers originate from an unknown primary origin. Some have a signet-ring cell (SRC) component. We report the medical history of three patients with SRC carcinoma expressing both the oestrogen (ER) and progesterone receptors (PR). Although no primary breast cancer could be identified, we considered these three patients as having metastatic breast cancer. All of them were therefore treated with standard breast anti-hormonal therapies and all demonstrated benefit. The pitfalls of clinical presentation, diagnostic work-up, and treatment are discussed.

[The ideal valvular prosthesis is still to come. Which factors can help decide between mechanical and bioprosthetic heart valve replacement?]. / La prothèse valvulaire idéale n'existe toujours pas. quels facteurs entrent en compte pour orienter les choix d'une valve mécanique ou biologique?

The prevalence of valvular heart diseases reaches 2.5% in the overall population. Aortic valve replacement is one of the most common surgical procedures. We report the story of a female patient whose aortic mechanical valve, implanted at the age of 54 years at the time of a mitral valve repair surgery, had to be replaced 14 years later, due to the development of a subvalvular pannus narrowing the valvular orifice. We use this clinical story to compare the advantages and disadvantages of repair surgery and valve replacement with a biological or mechanical prosthesis, and summarize the latest evidence for the choice of the most adequate prosthesis for a particular patient's profile.

[Mesenchymal stromal cells and organ transplantation]. / Cellules stromales mésenchymateuses et transplantation d'organes.

Mesenchymal stromal cells (MSC) are multipotent and self-renewing cells. MSC are studied for their in vivo and in vitro immunomodulatory effects, in the prevention or the treatment of isehemic injury, and for their potential properties of tissue or organ reconstruction. Over the last few years, the potential role of MSC in organ transplantation has been studied both in vitro and in vivo, and their properties make them an ideal potential cell therapy after solid organ transplantation. A prospective, controlled, phase 1-2 study has been initiated at the CHU of Liege, Belgium. This study assesses the potential risks and benefits of MSC infusion after liver or kidney transplantation. Even if the preliminary results of this study look promising, solely a prospective, randomized, large scale, phase 3 study will allow the clinical confirmation of the theoretical benefits of MSC in solid organ transplantation.

The ETHICA study (part II): simulation study of determinants and variability of ICU physician decisions in patients aged 80 or over.

PURPOSE: To assess physician decisions about ICU admission for life-sustaining treatments (LSTs). METHODS: Observational simulation study of physician decisions for patients aged ≥80 years. Each patient was allocated at random to four physicians who made decisions based on actual bed availability and existence of an additional bed before and after obtaining information on patient preferences. The simulations involved non-invasive ventilation (NIV), invasive mechanical ventilation (IMV), and renal replacement therapy after a period of IMV (RRT after IMV). RESULTS: The physician participation rate was 100/217 (46 %); males without religious beliefs predominated, and median ICU experience was 9 years. Among participants, 85.7, 78, and 62 % felt that NIV, IMV, or RRT (after IMV) was warranted, respectively. By logistic regression analysis, factors associated with admission were age <85 years, self-sufficiency, and bed availability for NIV and IMV. Factors associated with IMV were previous ICU stay (OR 0.29, 95 % CI 0.13-0.65, p = 0.01) and cancer (OR 0.23, 95 % CI 0.10-0.52, p = 0.003), and factors associated with RRT (after IMV) were living spouse (OR 2.03, 95 % CI 1.04-3.97, p = 0.038) and respiratory disease (OR 0.42, 95 % CI 0.23-0.76, p = 0.004). Agreement among physicians was low for all LSTs. Knowledge of patient preferences changed physician decisions for 39.9, 56, and 57 % of patients who disagreed with the initial physician decisions for NIV, IMV, and RRT (after IMV) respectively. An additional bed increased admissions for NIV and IMV by 38.6 and 13.6 %, respectively. CONCLUSIONS: Physician decisions for elderly patients had low agreement and varied greatly with bed availability and knowledge of patient preferences.

In vitro effect of cryptophycin 52 on microtubule assembly and tubulin: molecular modeling of the mechanism of action of a new antimitotic drug.

Cryptophycin 52 (C52) is a new synthetic compound of the cryptophycin family of antitumor agents that is currently undergoing clinical evaluation for cancer chemotherapy. The cryptophycin class of compounds acts on microtubules. This report details the mechanism by which C52 substoichiometrically inhibits tubulin self-assembly into microtubules. The inhibition data were analyzed through a model described by Perez-Ramirez [Perez-Ramirez, B., Andreu, J. M., Gorbunoff, M. J., and Timasheff, S. N. (1996) Biochemistry 35, 3277-3285]. We thereby determined the values of the apparent binding constant of the tubulin-C52 complex to the end of a growing microtubule (K(i)) and the apparent binding constant of C52 to tubulin (K(b)). The binding of C52 depended on tubulin concentration, and binding induced changes in the sedimentation pattern of tubulin, which indicates that C52 induces the self-association of tubulin and tubulin aggregates other than microtubules. Using analytical ultracentrifugation and electron microscopy, we show that C52 induces tubulin to form ring-shaped oligomers (single rings). We also show that C52 inhibits the formation of double rings from either GTP- or GDP-tubulin. In addition, the advances made by electron crystallography in understanding the structure of the tubulin and the microtubule allowed us to visualize the putative binding site of C52 and to reconstruct C52-induced ring oligomers by molecular modeling.

CD8beta endows CD8 with efficient coreceptor function by coupling T cell receptor/CD3 to raft-associated CD8/p56(lck) complexes.

The extraordinary sensitivity of CD8+ T cells to recognize antigen impinges to a large extent on the coreceptor CD8. While several studies have shown that the CD8beta chain endows CD8 with efficient coreceptor function, the molecular basis for this is enigmatic. Here we report that cell-associated CD8alphabeta, but not CD8alphaalpha or soluble CD8alphabeta, substantially increases the avidity of T cell receptor (TCR)-ligand binding. To elucidate how the cytoplasmic and transmembrane portions of CD8beta endow CD8 with efficient coreceptor function, we examined T1.4 T cell hybridomas transfected with various CD8beta constructs. T1.4 hybridomas recognize a photoreactive Plasmodium berghei circumsporozoite (PbCS) peptide derivative (PbCS (4-azidobezoic acid [ABA])) in the context of H-2K(d), and permit assessment of TCR-ligand binding by TCR photoaffinity labeling. We find that the cytoplasmic portion of CD8beta, mainly due to its palmitoylation, mediates partitioning of CD8 in lipid rafts, where it efficiently associates with p56(lck). In addition, the cytoplasmic portion of CD8beta mediates constitutive association of CD8 with TCR/CD3. The resulting TCR-CD8 adducts exhibit high affinity for major histocompatibility complex (MHC)-peptide. Importantly, because CD8alphabeta partitions in rafts, its interaction with TCR/CD3 promotes raft association of TCR/CD3. Engagement of these TCR/CD3-CD8/lck adducts by multimeric MHC-peptide induces activation of p56(lck) in rafts, which in turn phosphorylates CD3 and initiates T cell activation.

Three-dimensional structure of the lithostathine protofibril, a protein involved in Alzheimer's disease.

Neurodegenerative diseases are characterized by the presence of filamentous aggregates of proteins. We previously established that lithostathine is a protein overexpressed in the pre-clinical stages of Alzheimer's disease. Furthermore, it is present in the pathognomonic lesions associated with Alzheimer's disease. After self-proteolysis, the N-terminally truncated form of lithostathine leads to the formation of fibrillar aggregates. Here we observed using atomic force microscopy that these aggregates consisted of a network of protofibrils, each of which had a twisted appearance. Electron microscopy and image analysis showed that this twisted protofibril has a quadruple helical structure. Three-dimensional X-ray structural data and the results of biochemical experiments showed that when forming a protofibril, lithostathine was first assembled via lateral hydrophobic interactions into a tetramer. Each tetramer then linked up with another tetramer as the result of longitudinal electrostatic interactions. All these results were used to build a structural model for the lithostathine protofibril called the quadruple-helical filament (QHF-litho). In conclusion, lithostathine strongly resembles the prion protein in its dramatic proteolysis and amyloid proteins in its ability to form fibrils.