Double trouble during the left atrial appendage occlusion procedure.

Percutaneous structural interventions are being performed at increased numbers and rare findings or complications occur more frequently. Lipomatous hypertrophy of the interatrial septum (LHIS) is a relatively uncommon finding on transthoracic echocardiogram (TTE). The major challenge is the difficulty in performing transseptal puncture. We aimed to report the difficulties that were experienced during the left atrial appendage (LAA) closure in a case with an extreme form of LHIS.

Prognostic significance of serum galectin-3 in hospitalized patients with COVID-19.

BACKGROUND: There are no major tools that could predict disease severity in COVID-19. The aim of this study is to evaluate if serum galectin-3 levels can identify disease progression in COVID-19. METHODS: Patients that were hospitalized due to COVID-19 between March and June 2020 were included in this cross-sectional prospective study. Baseline demographic and clinical data in addition to levels of serum parameters including galectin-3 were measured at the time of hospital admission. Patients with COVID-19 were categorized into two groups (non-severe and severe illness). The need for ICU during hospital stay, duration from hospital admission to the transfer to the ICU, and the total length of hospital stay were recorded. RESULTS: A total of 175 patients were included in the study and among these, 64 patients formed the severe illness group whereas 111 comprised the non-severe illness group. There was statistically significant difference in terms of galectin-3 levels between groups (1.07 ± 0.75 vs 0.484 ± 0.317, p < 0.0001, respectively). Our results showed that galectin-3, IL-6 and CRP levels at admission were independent risk factors associated with transfer to the ICU whereas only galectin-3 was an independent factor for the need for advanced ventilatory support. Also, galectin-3 and IL-6 were independent risk factors related to in-hospital mortality. CONCLUSION: In conclusion, our results indicated that galectin-3 had moderate power in outlining disease severity and the need for ICU transfer throughout the clinical course in COVID-19.

Novel bilobe components in Trypanosoma brucei identified using proximity-dependent biotinylation.

The trypanosomes are a family of parasitic protists of which the African trypanosome, Trypanosoma brucei, is the best characterized. The complex and highly ordered cytoskeleton of T. brucei has been shown to play vital roles in its biology but remains difficult to study, in large part owing to the intractability of its constituent proteins. Existing methods of protein identification, such as bioinformatic analysis, generation of monoclonal antibody panels, proteomics, affinity purification, and yeast two-hybrid screens, all have drawbacks. Such deficiencies-troublesome proteins and technical limitations-are common not only to T. brucei but also to many other protists, many of which are even less well studied. Proximity-dependent biotin identification (BioID) is a recently developed technique that allows forward screens for interaction partners and near neighbors in a native environment with no requirement for solubility in nonionic detergent. As such, it is extremely well suited to the exploration of the cytoskeleton. In this project, BioID was adapted for use in T. brucei. The trypanosome bilobe, a discrete cytoskeletal structure with few known protein components, represented an excellent test subject. Use of the bilobe protein TbMORN1 as a probe resulted in the identification of seven new bilobe constituents and two new flagellum attachment zone proteins. This constitutes the first usage of BioID on a largely uncharacterized structure, and demonstrates its utility in identifying new components of such a structure. This remarkable success validates BioID as a new tool for the study of unicellular eukaryotes in particular and the eukaryotic cytoskeleton in general.

Multimodality Imaging of Intimal Sarcoma Causing Both Severe Mitral Stenosis and Mitral Regurgitation.

Intimal sarcomas (IS) are rare, malignant, rapidly progressive mesenchymal tumors that typically occur in the tunica intima of larger vessels, and they rarely involve the heart. IS are frequently misdiagnosed during the initial clinical presentation. This case report describes an uncommonly located IS, highlighting specific findings obtained through multimodality imaging.

Morphology of the trypanosome bilobe, a novel cytoskeletal structure.

The trypanosome bilobe is a cytoskeletal structure of unclear function. To date, four proteins have been shown to localize stably to it: TbMORN1, TbLRRP1, TbCentrin2, and TbCentrin4. In this study, a combination of immunofluorescence microscopy and electron microscopy was used to explore the morphology of the bilobe and its relationship to other nearby cytoskeletal structures in the African trypanosome procyclic trypomastigote. The use of detergent/salt-extracted flagellum preparations was found to be an effective way of discerning features of the cytoskeletal ultrastructure that are normally obscured. TbMORN1 and TbCentrin4 together define a hairpin structure comprising an arm of TbCentrin4 and a fishhook of TbMORN1. The two arms flank a specialized microtubule quartet and the flagellum attachment zone filament, with TbMORN1 running alongside the former and TbCentrin4 alongside the latter. The hooked part of TbMORN1 sits atop the flagellar pocket collar marked by TbBILBO1. The TbMORN1 bilobe occasionally exhibits tendrillar extensions that seem to be connected to the basal and probasal bodies. The TbMORN1 molecules present on these tendrils undergo higher rates of turnover than those for molecules on the main bilobe structure. These observations have been integrated with previous detailed descriptions of the cytoskeletal elements in trypanosome cells.

A role for Sar1 and ARF1 GTPases during Golgi biogenesis in the protozoan parasite Trypanosoma brucei.

A single Golgi stack is duplicated and partitioned into two daughter cells during the cell cycle of the protozoan parasite Trypanosoma brucei The source of components required to generate the new Golgi and the mechanism by which it forms are poorly understood. Using photoactivatable GFP, we show that the existing Golgi supplies components directly to the newly forming Golgi in both intact and semipermeabilized cells. The movement of a putative glycosyltransferase, GntB, requires the Sar1 and ARF1 GTPases in intact cells. In addition, we show that transfer of GntB from the existing Golgi to the new Golgi can be recapitulated in semipermeabilized cells and is sensitive to the GTP analogue GTPγS. We suggest that the existing Golgi is a key source of components required to form the new Golgi and that this process is regulated by small GTPases.

NLS-mediated NPC functions of the nucleoporin Pom121.

RanGTP mediates nuclear import and mitotic spindle assembly by dissociating import receptors from nuclear localization signal (NLS) bearing proteins. We investigated the interplay between import receptors and the transmembrane nucleoporin Pom121. We found that Pom121 interacts with importin alpha/beta and a group of nucleoporins in an NLS-dependent manner. In vivo, replacement of Pom121 with an NLS mutant version resulted in defective nuclear transport, induction of aberrant cytoplasmic membrane stacks and decreased cell viability. We propose that the NLS sites of Pom121 affect its function in NPC assembly both by influencing nucleoporin interactions and pore membrane structure.

The initiator core promoter element antagonizes repression of TATA-directed transcription by negative cofactor NC2.

Core promoter regions of protein-coding genes in metazoan genomes are structurally highly diverse and can contain several distinct core promoter elements, which direct accurate transcription initiation and determine basal promoter strength. Diversity in core promoter structure is an important aspect of transcription regulation in metazoans as it provides a basis for gene-selective function of activators and repressors. The basal activity of TATA box-containing promoters is dramatically enhanced by the initiator element (INR), which can function in concert with the TATA box in a synergistic manner. Here we report that a functional INR provides resistance to NC2 (Dr1/DRAP1), a general repressor of TATA promoters. INR-mediated resistance to NC2 is established during transcription initiation complex assembly and requires TBP-associated factors (TAFs) and TAF- and INR-dependent cofactor activity. Remarkably, the INR appears to stimulate TATA-dependent transcription similar to activators by strongly enhancing recruitment of TFIIA and TFIIB and, at the same time, by compromising NC2 binding.

MEL-28/ELYS is required for the recruitment of nucleoporins to chromatin and postmitotic nuclear pore complex assembly.

The metazoan nuclear envelope (NE) breaks down and re-forms during each cell cycle. Nuclear pore complexes (NPCs), which allow nucleocytoplasmic transport during interphase, assemble into the re-forming NE at the end of mitosis. Using in vitro NE assembly, we show that the vertebrate homologue of MEL-28 (maternal effect lethal), a recently discovered NE component in Caenorhabditis elegans, functions in postmitotic NPC assembly. MEL-28 interacts with the Nup107-160 complex (Nup for nucleoporin), an important building block of the NPC, and is essential for the recruitment of the Nup107-160 complex to chromatin. We suggest that MEL-28 acts as a seeding point for NPC assembly.