Possible role of 18-kDa translocator protein (TSPO) in etifoxine-induced reduction of direct twitch responses in isolated rat nerve-skeletal muscle preparations

Purpose: To determine the effects of etifoxine on directly-elicited twitch tension of isolated rat nerveskeletal muscle preparations and to propose a possible explanation of the mechanism of the observed effect.Methods: Striated muscles contractile activity was elicited by electrical field stimulation. The effects of etifoxine and nifedipine on direct single twitch response were studied.Results: The results demonstrate that the effect of etifoxine on skeletal muscle depends on the concentrations: low concentrations (10-8 М and 10-7 М) have little effect on twitch tension, whereas higher concentrations (10-6 М and 10-5 М) induced a significant decrease in the direct single twitch response in comparison to controls. The mean IC50 (reduction of directly-elicited twitch tension) of etifoxine was 0.85 x 10-6 M. The selective L-type calcium channel blocker nifedipine (10-5 М) induced a greater decrease in the muscle force than 10-6 М etifoxine. The different abilities of etifoxine and nifedipine to reduce direct single twitch response may be related to their distinct mechanisms of action. The observed effect of etifoxine could be more complex. Probably etifoxine acts as a non-selective agent not only on L-type calcium channels Cav1.1 localized in sarcolemma but also on 18-kDa translocator protein (TSPO) in skeletal muscle.Conclusion: Etifoxine-induced reduction of direct twitch responses could be attributed to an effect on TSPO and Cav1.1. Knowledge of the effects of TSPO ligands on the contraction of skeletal muscle might explain the role of TSPO in muscle contractility.Keywords: Etifoxine, TSPO, Calcium channels, Direct single twitch response, Striated muscl

Preparation of progressive antibacterial LDPE surface via active biomolecule deposition approach

The use of polymers in all aspects of daily life is increasing considerably, so there is high demand for polymers with specific properties. Polymers with antibacterial properties are highly needed in the food and medical industries. Low-density polyethylene (LDPE) is widely used in various industries, especially in food packaging, because it has suitable mechanical and safety properties. Nevertheless, the hydrophobicity of its surface makes it vulnerable to microbial attack and culturing. To enhance antimicrobial activity, a progressive surface modification of LDPE using the antimicrobial agent grafting process was applied. LDPE was first exposed to nonthermal radio-frequency (RF) plasma treatment to activate its surface. This led to the creation of reactive species on the LDPE surface, resulting in the ability to graft antibacterial agents, such as ascorbic acid (ASA), commonly known as vitamin C. ASA is a well-known antioxidant that is used as a food preservative, is essential to biological systems, and is found to be reactive against a number of microorganisms and bacteria. The antimicrobial effect of grafted LDPE with ASA was tested against two strong kinds of bacteria, namely, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), with positive results. Surface analyses were performed thoroughly using contact angle measurements and peel tests to measure the wettability or surface free energy and adhesion properties after each modification step. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the surface morphology or topography changes of LDPE caused by plasma treatment and ASA grafting. Surface chemistry was studied by measuring the functional groups and elements introduced to the surface after plasma treatment and ASA grafting, using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). These results showed wettability, adhesion, and roughness changes in the LDPE surface after plasma treatment, as well as after ASA grafting. This is a positive indicator of the ability of ASA to be grafted onto polymeric materials using plasma pretreatment, resulting in enhanced antibacterial activity. - 2019 by the authors.Funding: This publication was made possible by Award JSREP07-022-3-010 and NPRP10-0205-170349 from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors

Clinical comparative analysis of the outcomes with a yellow- and a violet-tinted intraocular lens

Letter to the Edito

Medlinella amphoroidea gen. et sp. nov. (Bacillariophyta) from the neck skin of Loggerhead sea turtles (Caretta caretta)

Medlinella amphoroidea gen. et sp. nov. is described from the dorsal neck skin of loggerhead sea turtles (Caretta caretta). The presence of girdle septa, multiple copulae, and the marine epizoic habitat of Medlinella amphoroidea are characteristic features shared with many species in the similar Tripterion, Chelonicola, and Poulinea genera. The semi-lanceolate valve shape, the asymmetric valve face with distinct dorsal and ventral striae, and the volate pore occlusions distinguish Medlinella from these genera. Medlinella amphoroidea accounted for up to 50% of all diatom valves on the skin of examined loggerhead turtles. Examination of the type slides of Tripterion kalamensis and T. philoderma for comparative purposes revealed morphological features that were either insufficiently or incorrectly described in the original publications. Our observations confirm that T. philoderma lacks septa and therefore does not conform to the genus description of Tripterion. The description of cingulum structure in Tripterion kalamensis is amended to identify multiple porose copulae that are open at one end. While the description of Medlinella creates another monotypic genus within a group of similar marine epizoic genera, we feel the novel character state (volate occlusions) present in this taxon is significant. Clearly, however, further phylogenetic analysis of morphological, or the development of molecular characters in the group of similar genera is required

Zero-shot interpretable phenotyping of postpartum hemorrhage using large language models

Many areas of medicine would benefit from deeper, more accurate phenotyping, but there are limited approaches for phenotyping using clinical notes without substantial annotated data. Large language models (LLMs) have demonstrated immense potential to adapt to novel tasks with no additional training by specifying task-specific instructions. Here we report the performance of a publicly available LLM, Flan-T5, in phenotyping patients with postpartum hemorrhage (PPH) using discharge notes from electronic health records (n = 271,081). The language model achieves strong performance in extracting 24 granular concepts associated with PPH. Identifying these granular concepts accurately allows the development of interpretable, complex phenotypes and subtypes. The Flan-T5 model achieves high fidelity in phenotyping PPH (positive predictive value of 0.95), identifying 47% more patients with this complication compared to the current standard of using claims codes. This LLM pipeline can be used reliably for subtyping PPH and outperforms a claims-based approach on the three most common PPH subtypes associated with uterine atony, abnormal placentation, and obstetric trauma. The advantage of this approach to subtyping is its interpretability, as each concept contributing to the subtype determination can be evaluated. Moreover, as definitions may change over time due to new guidelines, using granular concepts to create complex phenotypes enables prompt and efficient updating of the algorithm. Using this language modelling approach enables rapid phenotyping without the need for any manually annotated training data across multiple clinical use cases

Differential spatiotemporal targeting of Toxoplasma and Salmonella by GBP1 assembles caspase signalling platforms

Human guanylate binding proteins (GBPs), a family of IFNγ-inducible GTPases, promote cell-intrinsic defence against pathogens and host cell death. We previously identified GBP1 as a mediator of cell death of human macrophages infected with Toxoplasma gondii (Tg) or Salmonella Typhimurium (STm). How GBP1 targets microbes for AIM2 activation during Tg infection and caspase-4 during STm infection remains unclear. Here, using correlative light and electron microscopy and EdU labelling of Tg-DNA, we reveal that GBP1-decorated parasitophorous vacuoles (PVs) lose membrane integrity and release Tg-DNA for detection by AIM2-ASC-CASP8. In contrast, differential staining of cytosolic and vacuolar STm revealed that GBP1 does not contribute to STm escape into the cytosol but decorates almost all cytosolic STm leading to the recruitment of caspase-4. Caspase-5, which can bind LPS and whose expression is upregulated by IFNγ, does not target STm pointing to a key role for caspase-4 in pyroptosis. We also uncover a regulatory mechanism involving the inactivation of GBP1 by its cleavage at Asp192 by caspase-1. Cells expressing non-cleavable GBP1D192E therefore undergo higher caspase-4-driven pyroptosis during STm infection. Taken together, our comparative studies elucidate microbe-specific spatiotemporal roles of GBP1 in inducing cell death by leading to assembly and regulation of divergent caspase signalling platforms

Ubiquitin activation is essential for schizont maturation in Plasmodium falciparum blood-stage development

Ubiquitylation is a common post translational modification of eukaryotic proteins and in the human malaria parasite, Plasmodium falciparum (Pf) overall ubiquitylation increases in the transition from intracellular schizont to extracellular merozoite stages in the asexual blood stage cycle. Here, we identify specific ubiquitylation sites of protein substrates in three intraerythrocytic parasite stages and extracellular merozoites; a total of 1464 sites in 546 proteins were identified (data available via ProteomeXchange with identifier PXD014998). 469 ubiquitylated proteins were identified in merozoites compared with only 160 in the preceding intracellular schizont stage, suggesting a large increase in protein ubiquitylation associated with merozoite maturation. Following merozoite invasion of erythrocytes, few ubiquitylated proteins were detected in the first intracellular ring stage but as parasites matured through trophozoite to schizont stages the apparent extent of ubiquitylation increased. We identified commonly used ubiquitylation motifs and groups of ubiquitylated proteins in specific areas of cellular function, for example merozoite pellicle proteins involved in erythrocyte invasion, exported proteins, and histones. To investigate the importance of ubiquitylation we screened ubiquitin pathway inhibitors in a parasite growth assay and identified the ubiquitin activating enzyme (UBA1 or E1) inhibitor MLN7243 (TAK-243) to be particularly effective. This small molecule was shown to be a potent inhibitor of recombinant PfUBA1, and a structural homology model of MLN7243 bound to the parasite enzyme highlights avenues for the development of P. falciparum specific inhibitors. We created a genetically modified parasite with a rapamycin-inducible functional deletion of uba1; addition of either MLN7243 or rapamycin to the recombinant parasite line resulted in the same phenotype, with parasite development blocked at the schizont stage. Nuclear division and formation of intracellular structures was interrupted. These results indicate that the intracellular target of MLN7243 is UBA1, and this activity is essential for the final differentiation of schizonts to merozoites