Deciphering the intracellular metabolism of Listeria monocytogenes by mutant screening and modelling

Background: The human pathogen Listeria monocytogenes resides and proliferates within the cytoplasm of epithelial cells. While the virulence factors essentially contributing to this step of the infection cycle are well characterized, the set of listerial genes contributing to intracellular replication remains to be defined on a genome-wide level. Results: A comprehensive library of L. monocytogenes strain EGD knockout mutants was constructed upon insertion-duplication mutagenesis, and 1491 mutants were tested for their phenotypes in rich medium and in a Caco-2 cell culture assay. Following sequencing of the plasmid insertion site, 141 different genes required for invasion of and replication in Caco-2 cells were identified. Ten in-frame deletion mutants were constructed that confirmed the data. The genes with known functions are mainly involved in cellular processes including transport, in the intermediary metabolism of sugars, nucleotides and lipids, and in information pathways such as regulatory functions. No function could be ascribed to 18 genes, and a counterpart of eight genes is missing in the apathogenic species L. innocua. Mice infection studies revealed the in vivo requirement of IspE (Lmo0190) involved in mevalonate synthesis, and of the novel ABC transporter Lmo0135-0137 associated with cysteine transport. Based on the data of this genome-scale screening, an extreme pathway and elementary mode analysis was applied that demonstrates the critical role of glycerol and purine metabolism, of fucose utilization, and of the synthesis of glutathione, aspartate semialdehyde, serine and branched chain amino acids during intracellular replication of L. monocytogenes. Conclusion: The combination of a genetic screening and a modelling approach revealed that a series of transporters help L. monocytogenes to overcome a putative lack of nutrients within cells, and that a high metabolic flexibility contributes to the intracellular replication of this pathogen

Carboxymethyldextran-A2-Gd-DOTA enhancement patterns in the abdomen and pelvis in an animal model.

The aim of this study was to assess MR signal enhancement patterns of carboxymethyldextran (CMD)-A2-Gd-DOTA, a new macromolecular contrast agent, in the abdomen and pelvis of New Zealand white rabbits. Nine New Zealand white rabbits underwent MRI before and following injection of 0.05 mmol/kg body weight (bw) CMD-A2-Gd-DOTA (52.1 kDa), using turbo FLASH-, dynamic FLASH 60 degrees-, T1- and T2-weighted spin-echo and turbo spin-echo sequences up to 10 days p.i. Changes in blood and tissue signal intensities (deltaSI) and relaxation rates (deltaR1) were calculated. Differences between pre- and post-contrast MRI data were compared using the Scheffé test. CMD-A2-Gd-DOTA demonstrated significant blood-pool enhancement and significant tissue enhancement on T1-weighted images, whereas no significant signal changes were observed on T2-weighted images (P < 0.05). Kidney parenchyma, pelvis and bladder demonstrated a subsequent enhancement, resembling renal elimination of the majority of the contrast agent. Liver parenchyma demonstrated a slow, delayed decay of the contrast enhancement due to storage and biodegradation of larger subfractions of the contrast agent. All tissue signal intensities were back to baseline 10 days p.i. CMD-A2-Gd-DOTA is a new macromolecular contrast agent with blood-pool effect, significant signal enhancement of abdominal organs and pelvic bone marrow, partial storage in the liver and baseline tissue signal intensities by 10 days p.i

Soft robotic patient-specific hydrodynamic model of aortic stenosis and ventricular remodeling.

Aortic stenosis (AS) affects about 1.5 million people in the United States and is associated with a 5-year survival rate of 20% if untreated. In these patients, aortic valve replacement is performed to restore adequate hemodynamics and alleviate symptoms. The development of next-generation prosthetic aortic valves seeks to provide enhanced hemodynamic performance, durability, and long-term safety, emphasizing the need for high-fidelity testing platforms for these devices. We propose a soft robotic model that recapitulates patient-specific hemodynamics of AS and secondary ventricular remodeling which we validated against clinical data. The model leverages 3D-printed replicas of each patient's cardiac anatomy and patient-specific soft robotic sleeves to recreate the patients' hemodynamics. An aortic sleeve allows mimicry of AS lesions due to degenerative or congenital disease, whereas a left ventricular sleeve recapitulates loss of ventricular compliance and diastolic dysfunction (DD) associated with AS. Through a combination of echocardiographic and catheterization techniques, this system is shown to recreate clinical metrics of AS with greater controllability compared with methods based on image-guided aortic root reconstruction and parameters of cardiac function that rigid systems fail to mimic physiologically. Last, we leverage this model to evaluate the hemodynamic benefit of transcatheter aortic valves in a subset of patients with diverse anatomies, etiologies, and disease states. Through the development of a high-fidelity model of AS and DD, this work demonstrates the use of soft robotics to recreate cardiovascular disease, with potential applications in device development, procedural planning, and outcome prediction in industrial and clinical settings

Multiple sclerosis and access to healthcare in the Pays de la Loire region: Preliminary study based on 130 self-applied double questionnaires

AbstractObjectiveTo check whether the use of an autoquestionnaire is adapted to obtain information about perceptions of multiple sclerosis (MS) patients concerning access to healthcare in the Pays de la Loire region of France.Patients and methodsPatients with MS were asked to complete a questionnaire concerning access to 31 healthcare professionals or social services. The questionnaires were anonymous and consisted of one page for the patient and one page for a member of his or her entourage. The questionnaires were returned in a prepaid stamped addressed envelope. The first 130 exploitable questionnaires were analysed.ResultsOver 50% of patients with MS found access to general practitioners, neurologists, nurses and pharmacists useful, as well as access to less MS-specific specialists, for example, dentists, ophthalmologists or gynaecologists. Physical medicine and rehabilitation practitioners were not required until later in the course of the disease. Patients and their entourage rated the importance of access to care differently for bladder and sexual problems, and for support for cognitive and psychological problems.ConclusionThis study validates the use of a questionnaire to obtain information about patient perceptions of access to healthcare. The study also suggests a hierarchy of care needs, insufficient patient information, and disparities in access to care related to where the patients live