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Background: Patients with congenital heart disease (CHD) frequently have had valve interventions, including replacement with a mechanical valve (mechV). The impact of a mechV on clinical outcomes in patients undergoing ventricular assist device (VAD) implantation is not well characterized. Objectives: This study assessed VAD outcomes in patients with CHD and a mechV. Methods: All patients with a history of CHD (n = 433) in the Advanced Cardiac Therapies Improving Outcomes Network database were included in the study (January 2012-January 2023). Patient characteristics and outcomes were assessed among patients with a mechV and without a mechV. Results: Twenty-seven (6%) patients with CHD had a mechV at VAD implantation. Fourteen (52%) of the patients with mechV had univentricular anatomy and 13 (48%) had biventricular anatomy. Patients with mechV were older (4.9 vs 1.9 years, p = 0.02), smaller (14.9 vs 10.6 kg, p = 0.02), and had a higher interagency registry for mechanically assisted circulatory support profile (p = 0.01). Three (11%) patients with mechV experienced a valve-related complication. There was no difference in survival (p = 0.4) or ischemic stroke frequency (11% vs 13%, p = 1) between patients with mechV and non-mechV. Patients with mechV had higher frequency of hemorrhagic stroke (18% vs 4.7%, p = 0.01) and major bleeding (44% vs 26%, p = 0.04). Conclusions: Patients with CHD with a mechV have similar survival to patients with non-mechV; however, there is higher risk of bleeding including hemorrhagic stroke.

Given the high prevalence of Chagas disease in the Americas, we targeted the unique arginyl-tRNA synthetase of its causative agent Trypanosoma cruzi. Among their many possible uses, naphthalene-derived fluorescent ligands, such as ANS and bis-ANS, may be employed in pharmacokinetic research. Although ANS and bis-ANS have become prominent fluorescent probes for protein characterization, the structural and spectroscopic characteristics of protein-ANS/bis-ANS complexes remain largely unknown. Both fluorescent dyes bind to either the folded or partially folded hydrophobic regions of proteins. Additionally, they serve to identify molten globule-like intermediates. These probes have been used to study the folding problems of protein structures and the mechanisms of protein-protein interactions. ANS and bis-ANS exhibited significant enhancement and blue shift in their emission spectra upon binding to TcArgRS, the primary enzyme responsible for attaching l-arginine to its corresponding tRNA. Through fluorescence spectroscopy and computational studies, we concluded that bis-ANS binds more tightly to TcArgRS and that ATP affects bis-ANS fluorescence signal. Thus, these probes are useful resources for studying the intricate intermolecular relationships between proteins in terms of their structure, function, and mechanism. Our study provides a framework for identifying the hydrophobic regions present in TcArgRS. The utilization of hydrophobic patches on proteins for drug targeting is noteworthy because they can assist in identifying regions on the surface of proteins that are likely to interact with ligands. These patches help identify hotspot residues that play a vital role in determining binding affinity. Drugs are mainly small and hydrophobic in nature, and they target protein surfaces which have complementary properties. In this study, we elucidated the potential of TcArgRS as a target for combating trypanosomal diseases and extending life expectancy., (Copyright © 2024 Elsevier Inc. All rights reserved.)

We describe limitations in the use of 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) to examine unfolding intermediates associated with guanidinium chloride (GuHCl)-induced protein denaturation. Several studies have used alterations in fluorescence emission of bis-ANS to quantify the population of "molten globule" states. Our findings indicate that the observed changes in bis-ANS spectroscopic properties could originate from the interactions of bis-ANS and GuHCl and the aggregation of the dye at higher GuHCl concentrations. We posit that in the absence of additional complementary structural or spectroscopic measurements, the use of bis-ANS emission alone to monitor protein conformations can be misleading., (Copyright © 2011 Elsevier Inc. All rights reserved.)

We synthesized two sulfhydryl-reactive fluorescent probes, Br-ANT (2-amino-benzoic acid, 2-(bromoacetyl)hydrazide) and Br-MANT (N-[2-[(bromoacetyl)amino]ethyl]-2-(methylamino)benzamide). Br-ANT and Br-MANT contain an anthraniloyl and N-methyl anthraniloyl group, respectively, linked to the sulfhydryl-reactive bromoacetyl moiety. The cysteine adducts have absorption maxima at 323 and 326 nm, with molar extinction coefficients of 2100 and 2900 M-1 cm-1, for Br-ANT and Br-MANT, respectively, making these probes excellent acceptors for tryptophan. The absorption spectra and quantum yields were constant at pH levels useful for protein studies (pH 5-8). Quantum yields of Br-ANT and Br-MANT were 0.16 and 0.42, emission maxima were 432 and 440 nm, and fluorescence lifetimes were 1.3 and 7.8 ns, respectively. The emission of Br-ANT-Cys and Br-MANT-Cys shifted to shorter wavelengths with decreasing solvent polarity. Polarization values were maximal between 330 and 375 nm. Both probes reacted selectively and stoichiometrically with the single cysteine residue of a model protein. The labeled protein exhibited relatively long lifetimes (9-10 ns), suggesting that these probes will be generally useful for rotational studies.

Elongation factor Tu (EF-Tu) from Escherichia coli is shown here to polymerize under conditions of low ionic strength and slightly acidic pH. Several factors, such as decreasing pH, decreasing ionic strength, increasing temperature, and increasing protein concentration (up to 2.5 microM) enhance the rate of polymerization. Both EF-Tu.GTP and EF-Tu.GDP polymerized equally well under the conditions studied. A lag time was observed between the lowering of the pH and the onset of measurable polymerization, which was not overcome by addition of preformed polymer "seeds." Finally, addition of unpolymerized EF-Tu.GDP to a solution of polymerized EF-Tu.GDP appears to lead to formation of new polymers instead of addition to preexisting ones, which may suggest a size limit for polymers of EF-Tu.GDP.

Considerable metabolic energy is expended in ensuring that membranes possess a characteristic fatty acid composition. The nature of the specific requirement of the retina for high levels of docosahexaenoic acid (DHA) is as yet undefined. Previous work has speculated that DHA is required to maintain the fluid nature and permeability necessary for optimal retinal function. Cultured Y-79 retinoblastoma cells were grown in serum-containing media with and without supplemental DHA. Resultant changes in membrane fluidity were assessed using fluorescent probes. No differences were observed in rotational probe mobility as assessed by fluorescence polarization despite a fourfold increase in cellular DHA content. Lateral probe mobility as assessed by pyrene eximer formation was significantly enhanced in DHA-supplemented cells. Both the DHA content and total fatty acid unsaturation index in retinoblastoma cells were directly correlated with membrane fluidity as reported by eximer formation (Pearson's rho = 0.96 and 0.92, respectively). DHA supplementation also resulted in a significant increase in cellular choline uptake. We speculate that the effect of DHA content on retinal function may be mediated by changes in membrane fluidity and associated enzyme and transport activities.

The quenching by molecular oxygen of the fluorescence of several probes complexed to apohorseradish peroxidase has been studied by intensity and time-resolved fluorescence methods. The probes utilized include 1-anilino-8-naphthalene sulfonic acid, 4,4'-bis (1-anilino-8-naphthalene sulfonic acid), and 2-p-toluidinylnaphthalene-6-sulfonic acid. These results are contrasted to those obtained using apohorseradish peroxidase complexed with protoporphyrin IX. The resistance of these complexes to denaturation by guanidine hydrochloride was determined. The results demonstrate a dramatic increase in oxygen accessibility to the naphthalene probes compared to protoporphyrin IX, which can be correlated to the increased stability of the protein-protoporphyrin IX complex.