Collective magnetotaxis of microbial holobionts is optimized by the three-dimensional organization and magnetic properties of ectosymbionts.

Over the last few decades, symbiosis and the concept of holobiont-a host entity with a population of symbionts-have gained a central role in our understanding of life functioning and diversification. Regardless of the type of partner interactions, understanding how the biophysical properties of each individual symbiont and their assembly may generate collective behaviors at the holobiont scale remains a fundamental challenge. This is particularly intriguing in the case of the newly discovered magnetotactic holobionts (MHB) whose motility relies on a collective magnetotaxis (i.e., a magnetic field-assisted motility guided by a chemoaerotaxis system). This complex behavior raises many questions regarding how magnetic properties of symbionts determine holobiont magnetism and motility. Here, a suite of light-, electron- and X-ray-based microscopy techniques [including X-ray magnetic circular dichroism (XMCD)] reveals that symbionts optimize the motility, the ultrastructure, and the magnetic properties of MHBs from the microscale to the nanoscale. In the case of these magnetic symbionts, the magnetic moment transferred to the host cell is in excess (102 to 103 times stronger than free-living magnetotactic bacteria), well above the threshold for the host cell to gain a magnetotactic advantage. The surface organization of symbionts is explicitly presented herein, depicting bacterial membrane structures that ensure longitudinal alignment of cells. Magnetic dipole and nanocrystalline orientations of magnetosomes were also shown to be consistently oriented in the longitudinal direction, maximizing the magnetic moment of each symbiont. With an excessive magnetic moment given to the host cell, the benefit provided by magnetosome biomineralization beyond magnetotaxis can be questioned.

Multicolor Super-Resolution Microscopy of Protein Corona on Single Nanoparticles.

Nanoparticles represent a promising class of material for nanomedicine and molecular biosensing. The formation of a protein corona due to nonspecific particle-protein interactions is a determining factor for the biological fate of nanoparticles in vivo and strongly impacts the performance of nanoparticles when used as biosensors. Nonspecific interactions are usually highly heterogeneous, yet little is known about the heterogeneity of the protein corona that may lead to inter- and intraparticle differences in composition and protein distribution. Here, we present a super-resolution microscopic approach to study the protein corona on single silica nanoparticles and subsequent cellular interactions using multicolor stimulated emission depletion (STED) microscopy. We demonstrate that STED resolves structural features of protein corona on single particles including the distribution on the particle surface and the degree of protein internalization in porous particles. Using multicolor measurements of multiple labeled protein species, we determine the composition of the protein corona at the single-particle level. We quantify particle-to-particle differences in the composition and find that the composition is considerably influenced by the particle geometry. In a subsequent cellular uptake measurement, we demonstrate multicolor STED of protein corona on single particles internalized by cells. Our study shows that STED microscopy opens the window toward mechanistic understanding of protein coronas and aids in the rational design of nanoparticles as nanomedicines and biosensors.

Trauma Laparotomy in the UK: A Prospective National Service Evaluation.

BACKGROUND: Trauma patients requiring abdominal operation have considerable morbidity and mortality, yet no specific quality indicators are measured in the trauma systems of the UK. The aims of this study were to describe the characteristics and outcomes of patients undergoing emergency abdominal operation and key processes of care. STUDY DESIGN: A prospective multicenter service evaluation was conducted within all of the major trauma centers in the UK. The study was conducted during 6 months beginning in January 2019. Patients of any age undergoing laparotomy or laparoscopy within 24 hours of injury were included. Existing standards for related emergent conditions were used. RESULTS: The study included 363 patients from 34 hospitals. The majority were young men with no comorbidities who required operation to control bleeding (51%). More than 90% received attending-delivered care in the emergency department (318 of 363) and operating room (321 of 363). The overall mortality rate was 9%. Patients with blunt trauma had a greater risk of death compared with patients with penetrating injuries (16.6% vs 3.8%; risk ratio 4.3; 95% CI, 2.0 to 9.4). Patients in which the Major Hemorrhage Protocol (MHP) was activated and who received a blood transfusion (n = 154) constituted a high-risk subgroup, accounting for 45% of the study cohort but 97% of deaths and 96% of blood components transfused. The MHP subgroup had expedited timelines from emergency department arrival to knife to skin (MHP: median 119 minutes [interquartile range 64 to 218 minutes] vs no MHP: median 211 minutes [interquartile range 135 to 425 minutes]; p < 0.001). CONCLUSIONS: The majority of trauma patients requiring emergency abdominal operation received a high standard of expedited care in a maturing national trauma system. Despite this, mortality and resource use among high-risk patients remains considerable.

Enzyme Conformation Influences the Performance of Lipase-powered Nanomotors.

Enzyme-powered micro/nanomotors have myriads of potential applications in various areas. To efficiently reach those applications, it is necessary and critical to understand the fundamental aspects affecting the motion dynamics. Herein, we explored the impact of enzyme orientation on the performance of lipase-powered nanomotors by tuning the lipase immobilization strategies. The influence of the lipase orientation and lid conformation on substrate binding and catalysis was analyzed using molecular dynamics simulations. Besides, the motion performance indicates that the hydrophobic binding (via OTES) represents the best orienting strategy, providing 48.4 % and 95.4 % increase in diffusion coefficient compared to hydrophilic binding (via APTES) and Brownian motion (no fuel), respectively (with C[triacetin] of 100 mm). This work provides vital evidence for the importance of immobilization strategy and corresponding enzyme orientation for the catalytic activity and in turn, the motion performance of nanomotors, and is thus helpful to future applications.

Disposable amperometric immunosensor for Saccharomyces cerevisiae based on carboxylated graphene oxide-modified electrodes.

A sensitive and disposable amperometric immunosensor for Saccharomyces cerevisiae was constructed by using carbon screen-printed electrodes modified with propionic acid-functionalized graphene oxide as transduction element. The affinity-based biosensing interface was assembled by covalent immobilization of a specific polyclonal antibody on the carboxylate-enriched electrode surface via a water-soluble carbodiimide/N-hydroxysuccinimide coupling approach. A concanavalin A-peroxidase conjugate was further used as signaling element. The immunosensor allowed the amperometric detection of the yeast in buffer solution and white wine samples in the range of 10-107 CFU/mL. This electroanalytical device also exhibited low detection limit and high selectivity, reproducibility, and storage stability. The immunosensor was successfully validated in spiked white wine samples.

An InN/InGaN quantum dot electrochemical biosensor for clinical diagnosis.

Low-dimensional InN/InGaN quantum dots (QDs) are demonstrated for realizing highly sensitive and efficient potentiometric biosensors owing to their unique electronic properties. The InN QDs are biochemically functionalized. The fabricated biosensor exhibits high sensitivity of 97 mV/decade with fast output response within two seconds for the detection of cholesterol in the logarithmic concentration range of 1 × 10⁻6 M to 1 × 10⁻³ M. The selectivity and reusability of the biosensor are excellent and it shows negligible response to common interferents such as uric acid and ascorbic acid. We also compare the biosensing properties of the InN QDs with those of an InN thin film having the same surface properties, i.e., high density of surface donor states, but different morphology and electronic properties. The sensitivity of the InN QDs-based biosensor is twice that of the InN thin film-based biosensor, the EMF is three times larger, and the response time is five times shorter. A bare InGaN layer does not produce a stable response. Hence, the superior biosensing properties of the InN QDs are governed by their unique surface properties together with the zero-dimensional electronic properties. Altogether, the InN QDs-based biosensor reveals great potential for clinical diagnosis applications.

A large ventricular septal defect complicating resuscitation after blunt trauma.

A young adult pedestrian was admitted to hospital after being hit by a car. On arrival to the Accident and Emergency Department, the patient was tachycardic, hypotensive, hypoxic, and acidotic with a Glasgow Coma Scale of 3. Despite initial interventions, the patient remained persistently hypotensive. An echocardiogram demonstrated a traumatic ventricular septal defect (VSD) with right ventricular strain and increased pulmonary artery pressure. Following a period of stabilization, open cardiothoracic surgery was performed and revealed an aneurysmal septum with a single large defect. This was repaired with a bovine patch, resulting in normalization of right ventricular function. This case provides a vivid depiction of a large VSD in a patient following blunt chest trauma with hemodynamic compromise. In all thoracic trauma patients, and particularly those poorly responsive to resuscitation, VSDs should be considered. Relevant investigations and management strategies are discussed.

Microinjection of urocortin 2 into the dorsal raphe nucleus activates serotonergic neurons and increases extracellular serotonin in the basolateral amygdala.

The intra dorsal raphe nucleus (DRN) administration of corticotropin releasing hormone (CRF) inhibits serotonergic (5-HT) activity in this structure, an effect blocked by antagonists selective for the type 1 CRF receptor (CRF1). The DRN has a high density of the type 2 receptor (CRF2), and so the present experiments explored the impact of CRF2 activation within the DRN on 5-HT function. The intra-DRN administration of the selective CRF2 agonist urocortin 2 (Ucn 2) dose dependently increased 5-HT efflux in the basolateral amygdala, a projection region of the DRN. Intra-DRN Ucn 2 also increased c-fos expression in labeled 5-HT neurons. Both of these effects of Ucn 2 were completely blocked by intra-DRN antisauvagine-30 (ASV-30), a relatively selective CRF2 antagonist. These data suggest that CRF1 and CRF2 activation within the DRN affect 5-HT neurons in opponent fashion. Implications of these results for understanding the behavioral effects of CRF and other CRF-like ligands are discussed.