Deciphering Interactions between Potential Inhibitors and the Plasmodium falciparum DHODH Enzyme: A Computational Perspective.

Malaria is a parasitic disease that, in its most severe form, can even lead to death. Insect-resistant vectors, insufficiently effective vaccines, and drugs that cannot stop parasitic infestations are making the fight against the disease increasingly difficult. It is known that the enzyme dihydroorotate dehydrogenase (DHODH) is of paramount importance for the synthesis of pyrimidine from the Plasmodium precursor, that is, for its growth and reproduction. Therefore, its blockade can lead to disruption of the parasite's life cycle in the vertebrate host. In this scenario, PfDHODH inhibitors have been considered candidates for a new therapy to stop the parasitic energy source. Given what is known, in this work, we applied molecular fractionation with conjugated caps (MFCC) in the framework of the quantum formalism of density functional theory (DFT) to evaluate the energies of the interactions between the enzyme and the different triazolopyrimidines (DSM483, DMS557, and DSM1), including a complex carrying the mutation C276F. From these results, it was possible to identify the main features of each system, focusing on the wild-type and mutant PfDHODH and examining the major amino acid residues that are part of the four complexes. Our analysis provides new information that can be used to develop new drugs that could prove to be more effective alternatives to present antimalarial drugs.

In Silico Evaluation of the Binding Energies of Androgen Receptor Agonists in Wild-Type and Mutational Models.

Anabolic androgenic steroids (AAS) are substances with androgenic and anabolic characteristics. Among the many side effects of hormone therapy with AAS, the following stand out: heart problems, adrenal gland disorders, aggressive behavior, increased risk of prostate cancer, problems related to lack of libido and impotence. Such substances vary in the relationship between androgenic activity, and the activation of the androgen receptor (AR) is of fundamental importance for the singularity of the action of each AAS. In this sense, our study evaluates the aspects that comprise the interactions of testosterone agonists (TES), dihydrotestosterone (DHT) and tetrahydrogestrinone (THG) in complex with the AR. In addition, we also evaluated the impact of ligand-receptor affinity differences in a mutation model. We apply computational techniques based on density functional theory (DFT) and use, as methodology, Molecular Fractionation with Conjugate Caps (MFCC). The energetic specificities present in the interaction between the analyzed complexes attest that the highest affinity with the AR receptor is found for AR-THG, followed by AR-DHT, AR-TES and AR-T877A-DHT, respectively. Our results also show the differences and equivalences between the different agonists, in addition to evaluating the difference between the DHT ligand in complex with the wild-type and mutant receptor, presenting the main amino acid residues that involve the interaction with the ligands. The computational methodology used proves to be an operative and sophisticated choice to help in the search for pharmacological agents for various therapies that have androgen as a target.

Mortality in a swiftly repurposed hospital in northeast Brazil during the first and second COVID-19 waves: A retrospective cohort study.

Background: The first months of the coronavirus disease 2019 (COVID-19) pandemic demanded rapid re-organization of available local resources. This study evaluated the performance of a private hospital in the Brazilian state of Ceará that was swiftly repurposed into a public tertiary COVID-19 centre during the first wave of the COVID-19 pandemic, and how it improved in the second wave. Methods: This retrospective cohort study included 2492 patients with COVID-19 at Hospital Estadual Leonardo da Vinci (HELV) during the first and second waves. Demographic, clinical and laboratory data were collected using a dedicated web platform (ResCOVID). A Poisson regression model was used to estimate factors associated with in-hospital mortality. Results: Differences in demographics and clinical features were found between the two waves. There was reduced in-hospital mortality during the second wave (36.2%) in comparison with the first wave (48.8%). Invasive mechanical ventilation showed the strongest association with increased risk of death in both waves {first wave: relative risk (RR) 4.28 [95% confidence interval (CI) 2.86-6.41], P<0.001; second wave: RR 12.94 (95% CI 3.4-49.12), P<0.001}. Conclusions: HELV was a pillar in the strategic public health plan to respond to COVID-19 in Ceará, helping to assist a group of moderate-to-severe cases and reduce the pressure on emergency and primary care facilities. Although mortality in intubated individuals remained high, there was an overall decrease in the in-hospital mortality rate in the second wave.

Investigation of protein-protein interactions and hotspot region on the NSP7-NSP8 binding site in NSP12 of SARS-CoV-2.

Background: The RNA-dependent RNA polymerase (RdRp) complex, essential in viral transcription and replication, is a key target for antiviral therapeutics. The core unit of RdRp comprises the nonstructural protein NSP12, with NSP7 and two copies of NSP8 (NSP81 and NSP82) binding to NSP12 to enhance its affinity for viral RNA and polymerase activity. Notably, the interfaces between these subunits are highly conserved, simplifying the design of molecules that can disrupt their interaction. Methods: We conducted a detailed quantum biochemical analysis to characterize the interactions within the NSP12-NSP7, NSP12-NSP81, and NSP12-NSP82 dimers. Our objective was to ascertain the contribution of individual amino acids to these protein-protein interactions, pinpointing hotspot regions crucial for complex stability. Results: The analysis revealed that the NSP12-NSP81 complex possessed the highest total interaction energy (TIE), with 14 pairs of residues demonstrating significant energetic contributions. In contrast, the NSP12-NSP7 complex exhibited substantial interactions in 8 residue pairs, while the NSP12-NSP82 complex had only one pair showing notable interaction. The study highlighted the importance of hydrogen bonds and π-alkyl interactions in maintaining these complexes. Intriguingly, introducing the RNA sequence with Remdesivir into the complex resulted in negligible alterations in both interaction energy and geometric configuration. Conclusion: Our comprehensive analysis of the RdRp complex at the protein-protein interface provides invaluable insights into interaction dynamics and energetics. These findings can guide the design of small molecules or peptide/peptidomimetic ligands to disrupt these critical interactions, offering a strategic pathway for developing effective antiviral drugs.

A quantum biochemistry investigation of the protein-protein interactions for the description of allosteric modulation on biomass-degrading chimera.

The worldwide dependence of population on fossil fuels continues to have several harmful implications for the environment. Bioethanol is an excellent option for renewable fuel to replace the current greenhouse gas emitters. In addition, its production by enzymatic route has gained space among the industrial processes because it replaces the traditional acid treatment. Due to its high versatility, the xylanase family is used in this process as an accessory enzyme for degrading the lignocellulosic substrate of biomass. A chimera built by a xylanolytic domain (Xyl) and a xylose-binding protein (XBP) showed an experimentally improved catalytic efficiency and interdomain allosteric modulation after xylose binding. In this context, we performed a quantum biochemistry characterization of the interactions between these domains and dynamic cross-correlation (DCC) analysis after performing molecular dynamics (DM) simulations of the systems in the presence and absence of xylose in the XBP active site. We used the density functional theory (DFT) within the molecular fractionation with the conjugated caps (MFCC) approach to describe the pair energies, and the corresponding energy difference between the chimera domains responsible for the allosteric effect and amino acid DCC to evaluate the interdomain coupling differences between the energy states. The detailed energetic investigation together with the related structural and dynamics counterparts revealed the molecular mechanisms of chimeric improvement of the xylanase activity observed experimentally. This mechanism was correlated with greater stability and high connectivity at the interdomain interface in the xylose bound relative to the free chimera. We identify the contributions of hydrogen bonds, hydrophobic interactions and water-mediated interactions in the interdomain region responsible for stability together with the structural and dynamical elements related to the allosteric effect. Taken together, these observations led to a comprehensive understanding of the chimera's modulatory action that occurs through the formation of a highly connected interface that makes the essential movements related to xylanolytic activity in xylanase correlated to those of the xylose-binding protein.

An interview with José Xavier Neto. Interviewed by Eva Amsen.

The Latin American Society for Developmental Biology (LASDB) is getting ready for their Sixth International Meeting, which will be held in Montevideo, Uruguay, from April 26th to 29th, 2012. To find out more about the society, and about developmental biology in Latin America, we talked to LASDB president José Xavier Neto, who studies heart morphogenesis at the Laboratório Nacional de Biociências in Sao Paulo, Brazil.

Elevated expression of MeCP2 in cardiac and skeletal tissues is detrimental for normal development.

MeCP2 plays a critical role in interpreting epigenetic signatures that command chromatin conformation and regulation of gene transcription. In spite of MeCP2's ubiquitous expression, its functions have always been considered in the context of brain physiology. In this study, we demonstrate that alterations of the normal pattern of expression of MeCP2 in cardiac and skeletal tissues are detrimental for normal development. Overexpression of MeCP2 in the mouse heart leads to embryonic lethality with cardiac septum hypertrophy and dysregulated expression of MeCP2 in skeletal tissue produces severe malformations. We further show that MeCP2's expression in the heart is developmentally regulated; further suggesting that it plays a key role in regulating transcriptional programs in non-neural tissues.

Evolução dos conceitos sobre a etiopatogenia das doenças cardíacas congênitas / Evolution of the concepts in congenital heart disease

Doenças cardíacas congênitas representam um alto custo à sociedade. Apesar dos grandes avanços cirúrgicos do século 20, o entendimento dos mecanismos de embriogenia cardíaca não seguiu o mesmo ritmo. Esse panorama foi modificado nos últimos 10 anos pelos progressos em biologia do desenvolvimento e genética. Utilizando diversos modelos animais e aplicando técnicas de biologia molecular à genética humana foi possível definir um catálogo de genes envolvidos em desenvolvimento e doenças cardíacas. A identificação desses genes no contexto familiar mudou a visão tradicional que considerava as doenças cardíacas congênitas como necessariamente complexas e multifatoriais. Mutações isoladas em genes em genes como NKX-2.5 e TBX-5 causam lesões tão diversas quanto as associadas à tetralogia de Fallot e defeitos septais e, em adição, mutações em genes diversos podem ter manifestações semelhantes. Expressão variável e heterogeneidade genética são, portanto, marcas registradas da doença cardíaca congênita familiar, mas sua relevância no contexto esporádico, o mais comum, ainda é desconhecida. Em resumos, avanços recentes abriram as perspectivas para um entendimento fisiopatológico das doenças cardíacas congênitas. O grande desafio da atualidade é integrar os avanços moleculares com a prática tanto clínica como cirúrgica

Síndrome cervical: ensaio com vasodilatador coadjuvando o tratamento físico / Cervical syndrome: test with vasodilator besides physical treatment

O autor faz uma revisäo na fisiopatologia das desordens na coluna cervical e apresenta casuística de 119 pacientes portadores de injúrias cervicais com múltipla sintomatologia. Os pacientes foram divididos em dois grupos: no grupo controle utiliza traçäo cervical e ondas curtas e no grupo teste introduz substância alfa-adrenolítica (Nicergolina), além do tratamento fisiátrico, com o qual obtém melhores resultados na reduçäo de zumbidos e alteraçöes do equilíbrio