Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 134
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Phys Chem Chem Phys ; 26(11): 8973-8981, 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38436427

RESUMO

We investigated the effects of 1-ethyl-3-methylimidazolium chloride ([EMIM][Cl]) and choline chloride ([Chol][Cl]) on the local environment and conformational landscapes of Trp-cage and Trpzip4 mini-proteins using experimental and computational approaches. Fluorescence experiments and computational simulations revealed distinct behaviors of the mini-proteins in the presence of these organic salts. [EMIM][Cl] showed a strong interaction with Trp-cage, leading to fluorescence quenching and destabilization of its native structural interactions. Conversely, [Chol][Cl] had a negligible impact on Trp-cage fluorescence at low concentrations but increased it at high concentrations, indicating a stabilizing role. Computational simulations elucidated that [EMIM][Cl] disrupted the hydrophobic core packing and decreased proline-aromatic residue contacts in Trp-cage, resulting in a more exposed environment for Trp residues. In contrast, [Chol][Cl] subtly influenced the hydrophobic core packing, creating a hydrophobic environment near the tryptophan residues. Circular dichroism experiments revealed that [Chol][Cl] stabilized the secondary structure of both mini-proteins, although computational simulations did not show significant changes in secondary content at the explored concentrations. The simulations also demonstrated a more rugged free energy landscape for Trp-cage and Trpzip4 in [EMIM][Cl], suggesting destabilization of the tertiary structure for Trp-cage and secondary structure for Trpzip4. Similar fluorescence trends were observed for Trpzip4, with [EMIM][Cl] quenching fluorescence and exhibiting stronger interaction, while [Chol][Cl] increased the fluorescence at high concentrations. These findings highlight the interplay between [EMIM][Cl] and [Chol][Cl] with the mini-proteins and provide a detailed molecular-level understanding of how these organic salts impact the nearby surroundings and structural variations. Understanding such interactions is valuable for diverse applications, from biochemistry to materials science.


Assuntos
Dobramento de Proteína , Sais , Estrutura Secundária de Proteína
2.
Mol Pharm ; 20(5): 2352-2361, 2023 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-37014806

RESUMO

Current antibody (Ab) therapies require development of stable formulations and an optimal delivery system. Here, we present a new strategy to create a single-administration long-lasting Ab-delivery microarray (MA) patch, which can carry high doses of thermally stabilized Abs. The MA fabricated by an additive three-dimensional manufacturing technology can be fully embedded into the skin via a single application to deliver doses of Abs at multiple programmable time points, thus sustaining Ab concentrations in systemic circulation. We developed an MA formulation that stabilized and delivered human immunoglobulins (hIg) in a time-controlled manner while maintaining their structure and functionality. As an example, the b12 Ab─a broadly neutralizing Ab against HIV-1─maintained antiviral activity in vitro after MA manufacturing and heat exposure. Pharmacokinetic studies of MA patch-delivered hIg in rats successfully provided a proof of concept for concurrent and time-delayed Ab delivery. These MA patches codeliver different Abs, providing a tool for expanded protection against viral infections or combination HIV therapy and prevention.


Assuntos
Anticorpos , Infecções por HIV , Humanos , Ratos , Animais , Pele , Infecções por HIV/tratamento farmacológico , Infecções por HIV/prevenção & controle
3.
Phys Chem Chem Phys ; 24(17): 10365-10372, 2022 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-35438103

RESUMO

Long-term preservation of proteins at room temperature continues to be a major challenge. Towards using ionic liquids (ILs) to address this challenge, here we present a combination of experiments and simulations to investigate changes in lysozyme upon rehydration from IL mixtures using two imidazolium-based ILs (1-ethyl-3-methylimidazolium ethylsulfate, [EMIM][EtSO4] and 1-ethyl-3-methylimidazolium diethylphosphate, [EMIM][Et2PO4]). Various spectroscopic experiments and molecular dynamics simulations are performed to ascertain the structure and activity of lysozyme. Circular dichroism spectroscopy confirms that lysozyme maintains its secondary structure upon rehydration, even after 295 days. Increasing the IL concentration decreases the activity of lysozyme and is ultimately quenched at sufficiently high IL concentrations, but the rehydration of lysozyme from high IL concentrations completely restores its activity. Such rehydration occurs in the most common lysozyme activity assay, but without careful attention, this effect on the IL concentration can be overlooked. From simulations we observe occupation of [EMIM+] ions near the vicinity of the active site and the ligand-lysozyme complex is less stable in the presence of ILs, which results in the reduction of lysozyme activity. Upon rehydration, fast leaving of [EMIM+] is observed and the availability of active site is restored. In addition, suppression of structural fluctuations is also observed when in high IL concentrations, which also explains the decrease of activity. This structure suppression is recovered after undergoing rehydration. The return of native protein structure and activity indicates that after rehydration lysozyme returns to its original state. Our results also suggest a simple route to protein recovery following extended storage.


Assuntos
Líquidos Iônicos , Hidratação , Líquidos Iônicos/química , Simulação de Dinâmica Molecular , Muramidase/química , Estrutura Secundária de Proteína
4.
BMC Bioinformatics ; 22(1): 389, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34330209

RESUMO

BACKGROUND: Antimicrobial peptides (AMPs) are oligopeptides that act as crucial components of innate immunity, naturally occur in all multicellular organisms, and are involved in the first line of defense function. Recent studies showed that AMPs perpetuate great potential that is not limited to antimicrobial activity. They are also crucial regulators of host immune responses that can modulate a wide range of activities, such as immune regulation, wound healing, and apoptosis. However, a microorganism's ability to adapt and to resist existing antibiotics triggered the scientific community to develop alternatives to conventional antibiotics. Therefore, to address this issue, we proposed Co-AMPpred, an in silico-aided AMP prediction method based on compositional features of amino acid residues to classify AMPs and non-AMPs. RESULTS: In our study, we developed a prediction method that incorporates composition-based sequence and physicochemical features into various machine-learning algorithms. Then, the boruta feature-selection algorithm was used to identify discriminative biological features. Furthermore, we only used discriminative biological features to develop our model. Additionally, we performed a stratified tenfold cross-validation technique to validate the predictive performance of our AMP prediction model and evaluated on the independent holdout test dataset. A benchmark dataset was collected from previous studies to evaluate the predictive performance of our model. CONCLUSIONS: Experimental results show that combining composition-based and physicochemical features outperformed existing methods on both the benchmark training dataset and a reduced training dataset. Finally, our proposed method achieved 80.8% accuracies and 0.871 area under the receiver operating characteristic curve by evaluating on independent test set. Our code and datasets are available at https://github.com/onkarS23/CoAMPpred .


Assuntos
Algoritmos , Aprendizado de Máquina , Simulação por Computador , Proteínas Citotóxicas Formadoras de Poros , Curva ROC
5.
Phys Chem Chem Phys ; 22(35): 19779-19786, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32844828

RESUMO

Ionic liquids (ILs) are gaining attention as protein stabilizers and refolding additives. However, varying degrees of success with this approach motivates the need to better understand fundamental IL-protein interactions. A combination of experiment and simulation is used to investigate the thermal unfolding of lysozyme in the presence of two imidazolium-based ILs (1-ethyl-3-methylimidazolium ethylsulfate, [EMIM][EtSO4] and 1-ethyl-3-methylimidazolium diethylphosphate, [EMIM][Et2PO4]). Both ILs reduce lysozyme melting temperature Tm, but more gradually than strong denaturants. [EMIM][Et2PO4] lowers lysozyme Tm more readily than [EMIM][EtSO4], as well as requiring less energy to unfold the protein, as determined by the calorimetric enthalpy ΔH. Intrinsic fluorescence measurements indicate that both ILs bind to tryptophan residues in a dynamic mode, and furthermore, molecular dynamics simulations show a high density of [EMIM]+ near lysozyme's Trp62 residue. For both ILs approximately half of the [EMIM]+ cations near Trp62 show perfect alignment of their respective rings. The [EMIM]+ cations, having a "local" effect in binding to tryptophan, likely perturb a critically important Arg-Trp-Arg bridge through favorable π-π and cation-π interactions. Simulations show that the anions, [EtSO4]- and [Et2PO4]-, interact in a "global" manner with lysozyme, due to this protein's strong net positive charge. The anions also determine the local distribution of ions surrounding the protein. [Et2PO4]- is found to have a closer first coordination shell around the protein and stronger Coulomb interactions with lysozyme than [EtSO4]-, which could explain why the former anion is more destabilizing. Patching of ILs to the protein surface is also observed, suggesting there is no universal IL solvent for proteins, and highlighting the complexity of the IL-protein environment.


Assuntos
Líquidos Iônicos/química , Muramidase/química , Desdobramento de Proteína/efeitos dos fármacos , Animais , Galinhas , Imidazóis/química , Simulação de Dinâmica Molecular , Organofosfatos/química , Estabilidade Proteica/efeitos dos fármacos , Termodinâmica , Temperatura de Transição/efeitos dos fármacos
6.
Int J Mol Sci ; 21(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041193

RESUMO

RNA-Seq technology was used to analyze the transcriptome of two rice hybrids, Ajay (based on wild-abortive (WA)-cytoplasm) and Rajalaxmi (based on Kalinga-cytoplasm), and their respective parents at the panicle initiation (PI) and grain filling (GF) stages. Around 293 and 302 million high quality paired-end reads of Ajay and Rajalaxmi, respectively, were generated and aligned against the Nipponbare reference genome. Transcriptome profiling of Ajay revealed 2814 and 4819 differentially expressed genes (DEGs) at the PI and GF stages, respectively, as compared to its parents. In the case of Rajalaxmi, 660 and 5264 DEGs were identified at PI and GF stages, respectively. Functionally relevant DEGs were selected for validation through qRT-PCR, which were found to be co-related with the expression patterns to RNA-seq. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated significant DEGs enriched for energy metabolism pathways, such as photosynthesis, oxidative phosphorylation, and carbon fixation, at the PI stage, while carbohydrate metabolism-related pathways, such as glycolysis and starch and sucrose metabolism, were significantly involved at the GF stage. Many genes involved in energy metabolism exhibited upregulation at the PI stage, whereas the genes involved in carbohydrate biosynthesis had higher expression at the GF stage. The majority of the DEGs were successfully mapped to know yield related rice quantitative trait loci (QTLs). A set of important transcription factors (TFs) was found to be encoded by the identified DEGs. Our results indicated that a complex interplay of several genes in different pathways contributes to higher yield and vigor in rice hybrids.


Assuntos
Perfilação da Expressão Gênica/métodos , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/genética , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Metabolismo Energético , Regulação da Expressão Gênica de Plantas , Oryza/genética , Locos de Características Quantitativas , Análise de Sequência de RNA
7.
Langmuir ; 35(45): 14586-14595, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31621330

RESUMO

The nature of counter-ions governs the micellar and structural characteristics of surface-active ionic liquids (SAILs). Especially, the introduction of aromatic counter-ions significantly increases their surface adsorption and induces the formation of various types of aggregates like prolate ellipsoidal micelles, rodlike micelles, vesicles, lamellars, etc. The present study reports the role of charge delocalization of two different aromatic counter-ions in the micellization behavior of their respective SAILs in aqueous medium. For this purpose, we have synthesized two SAILs, namely, 1-tetradecyl-3-methylimidzolium phenolate [C14mim][PO] and 1-tetradecyl-3-methylimidzolium benzoate [C14mim][BZ]. The O-atom of phenolate (PO-) possesses negative charge, which is delocalized on its phenyl ring. Conversely, the negative charge of benzoate (BZ-) is not delocalized on its phenyl ring. The more hydrophobic BZ- counter-ion increases the hydrophobic interactions and reduces the electrostatic repulsions more efficiently as compared to PO-, which results in a lower critical micelle concentration (cmc) of [C14mim][BZ] than that of [C14mim][PO]. Interfacial properties obtained by tensiometry reveal better surface activity and absorption efficiency of [C14mim][BZ] as compared to [C14mim][PO]. The increase of cmc and degree of counter-ion binding (ß) with the rise of temperature for both SAILs has been observed by conductometry. The decrease in the polarity of pyrene microenvironment explains the higher compactness of [C14mim][BZ] aggregates than that of [C14mim][PO], observed by fluorimetry. The position of PO- and BZ- is in the stern and palisade layers of C14mim+ aggregates, respectively, located by 1H NMR. The existence of prolate ellipsoidal micelles for both SAILs has been established by small-angle neutron scattering measurements. Thus, the interfacial and bulk properties of [C14mim][PO] lie somewhere in between those of the SAILs having perfect aromatic counter-ions, [C14mim][BZ], and the SAILs having regular inorganic counter-ions like Cl-, Br-, etc.

8.
Indian J Urol ; 34(4): 287-291, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30337785

RESUMO

INTRODUCTION: Drugs causing ureteral relaxation are used for medical expulsive therapy (MET) for stones. We investigated the in vitro ability of tadalafil to cause relaxation of potassium chloride (KCl)-induced contractions of isolated human ureteral tissue. MATERIALS AND METHODS: Eight grossly normal proximal ureteral tissues were collected from the radical and donor nephrectomy specimen. The standard organ bath protocol was followed. Ureteral contractions were induced with 80 mM KCl before and after exposure to tadalafil. RESULTS: The median amplitude and frequency of KCl-induced contractions and the median area under the contractility curve (AUCC) after exposure to 20 µM tadalafil showed significant reductions compared to that of before exposure to tadalafil (7.87 cm, 3.79/min, and 2.98 cm2, respectively, versus 9.37 cm, 4.48/min, and 4.50 cm2, respectively; P = 0,026, 0.008, and 0.008, respectively). After exposure to 40 µM tadalafil, the median amplitude and frequency of KCl-induced contractions and AUCC (4.50 cm, 2.56/min, and 0.92 cm2, respectively) showed significant reductions compared to that of before exposure to tadalafil (7.62 cm, 3.88/min, and 3.32 cm2, respectively; P = 0.008, 0.016, and 0.008, respectively). However, reductions in the parameters after exposure to 20 µM and 40 µM tadalafil were similar (P = 0.065, 0.195, and 0.130, respectively, for median amplitude, frequency, and AUCC). CONCLUSION: Tadalafil reduces KCl-induced contractions of isolated human ureteral tissue in vitro. No incremental relaxations in contractions occurred by increasing the dose of tadalafil from 20 µM to 40 µM.

9.
Indian J Urol ; 33(2): 169-170, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28469309

RESUMO

A case of chronic ureteral obstruction secondary to radiation-related ureteral stricture producing a classic "negative pyelogram" on intravenous urography is presented.

10.
Indian J Urol ; 33(2): 173-174, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28469311

RESUMO

Isolated bilateral inguinal vesical hernia with urinary bladder as the only content is very rare. "Pelvic Mickey mouse" sign is a radiological sign described classically for bilateral inguinal vesical hernia on transverse axial imaging. Another imaging finding of a "Flying-saucer in the pelvis" sign seen on conventional intravenous urography is being presented.

11.
BMC Bioinformatics ; 17(Suppl 17): 478, 2016 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-28155640

RESUMO

BACKGROUND: The human immunodeficiency virus type 1 (HIV-1) aspartic protease is an important enzyme owing to its imperative part in viral development and a causative agent of deadliest disease known as acquired immune deficiency syndrome (AIDS). Development of HIV-1 protease inhibitors can help understand the specificity of substrates which can restrain the replication of HIV-1, thus antagonize AIDS. However, experimental methods in identification of HIV-1 protease cleavage sites are generally time-consuming and labor-intensive. Therefore, using computational methods to predict cleavage sites has become highly desirable. RESULTS: In this study, we propose a prediction method in which sequence, structural, and physicochemical features are incorporated in various machine learning algorithms. Then, a bidirectional stepwise selection algorithm is incorporated in feature selection to identify discriminative features. Further, only the selected features are calculated by various encoding schemes and used as input for decision trees, logistic regression, and artificial neural networks. Moreover, a more rigorous three-way data split procedure is applied to evaluate the objective performance of cleavage site prediction. Four benchmark datasets collected from previous studies are used to evaluate the predictive performance. CONCLUSIONS: Experiment results showed that combinations of sequence, structure, and physicochemical features performed better than single feature type for identification of HIV-1 protease cleavage sites. In addition, incorporation of stepwise feature selection is effective to identify interpretable biological features to depict specificity of the substrates. Moreover, artificial neural networks perform significantly better than the other two classifiers. Finally, the proposed method achieved 80.0% ~ 97.4% in accuracy and 0.815 ~ 0.995 evaluated by independent test sets in a three-way data split procedure.


Assuntos
Biologia Computacional/métodos , Protease de HIV/metabolismo , HIV-1/enzimologia , Redes Neurais de Computação , Algoritmos , Sequência de Aminoácidos , Confiabilidade dos Dados , Árvores de Decisões , Infecções por HIV , Humanos , Conformação Proteica , Especificidade por Substrato
12.
Mol Genet Genomics ; 291(4): 1783-94, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27299359

RESUMO

African wild rice Oryza brachyantha (FF), a distant relative of cultivated rice Oryza sativa (AA), carries genes for pests and disease resistance. Molecular marker assisted alien gene introgression from this wild species to its domesticated counterpart is largely impeded due to the scarce availability of cross-transferable and polymorphic molecular markers that can clearly distinguish these two species. Availability of the whole genome sequence (WGS) of both the species provides a unique opportunity to develop markers, which are cross-transferable. We observed poor cross-transferability (~0.75 %) of O. sativa specific sequence tagged microsatellite (STMS) markers to O. brachyantha. By utilizing the genome sequence information, we developed a set of 45 low cost PCR based co-dominant polymorphic markers (STS and CAPS). These markers were found cross-transferrable (84.78 %) between the two species and could distinguish them from each other and thus allowed tracing alien genome introgression. Finally, we validated a Monosomic Alien Addition Line (MAAL) carrying chromosome 1 of O. brachyantha in O. sativa background using these markers, as a proof of concept. Hence, in this study, we have identified a set molecular marker (comprising of STMS, STS and CAPS) that are capable of detecting alien genome introgression from O. brachyantha to O. sativa.


Assuntos
Primers do DNA/genética , DNA de Plantas/genética , Marcadores Genéticos , Oryza/genética , Mapeamento Cromossômico , Cruzamentos Genéticos , Resistência à Doença , Etiquetas de Sequências Expressas , Genoma de Planta , Repetições de Microssatélites , Polimorfismo Genético , Reprodutibilidade dos Testes
13.
Langmuir ; 32(26): 6638-47, 2016 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-27267864

RESUMO

Catanionic surfactant-hydrotrope mixtures have proven to be a striking alternative to tune microstructures over a wide range of compositions and also to minimize precipitation that is normally observed in catanionic mixtures at an equimolar ratio. These mixtures are supposed to be of great relevance in biological systems when a hydrotrope is a "drug". Keeping this in view, here we report composition- and dilution-induced structural changes in a catanionic mixture comprising ionic liquids (ILs), such as 1-dodecyl-3-methylimidazolium bromide (C12mimBr)/1-tetradecyl-3-methylimidazolium bromide (C14mimBr), and a drug, diclofenac sodium (DFNa), in aqueous solution. The structural changes are probed by small-angle neutron scattering (SANS), dynamic light scattering (DLS), and zeta-potential measurements. SANS data and size distribution curves clearly depict the formation of low curvature structures on going from the cation-rich to anion-rich composition up to a 0.7 mole fraction of DFNa (XDFNa). The amphiphilic nature of DFNa is supposed to alter the surface charge density, which is provoked by its incorporation into resulting aggregates, as confirmed by modified zeta-potential values. The modification of the average packing parameter resulting from the IL and DFNa complexation equilibrium seems to play a vital role in bringing out structural transitions of mixed aggregates. We also focused our attention to study the effect of dilution in concentrations ranging from 100 to 25 mM. At XDFNa = 0.0 and 0.1, the size of prolate ellipsoids decreases on dilution, mimicking classic behavior, but an opposite trend is observed at other XDFNa values. Dilution-induced transformation to larger aggregates is thought to be driven by the release of DFNa molecules from the mixed micelles on account of the critical micelle concentration (cmc) (solubility) mismatch between the two components. The role of other interactions such as cation-π and π-π in stabilizing the mixed aggregates in addition to hydrophobic interactions is probed by (1)H NMR.

14.
Br J Clin Pharmacol ; 81(6): 1142-52, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26799162

RESUMO

AIM: The aim was to examine the influence of CYP2C19 variants and associated haplotypes on the disposition of tamoxifen and its metabolites, particularly norendoxifen (NorEND), in Asian patients with breast cancer. METHODS: Sixty-six CYP2C19 polymorphisms were identified in healthy Asians (n = 240), of which 14 were found to be tightly linked with CYP2C19*2, CYP2C19*3 and CYP2C19*17. These 17 SNPs were further genotyped in Asian breast cancer patients receiving tamoxifen (n = 201). Steady-state concentrations of tamoxifen and its metabolites were quantified using liquid chromatography­mass spectrometry. Non-parametric tests and regression methods were implemented to evaluate genotypic­phenotypic associations and haplotypic effects of the SNPs. RESULTS: CYP2C19 functional polymorphisms and their linked SNPs were not significantly associated with plasma concentrations of tamoxifen and its main metabolites N-desmethyltamoxifen, (Z)-4-hydroxytamoxifen and (Z)-Endoxifen. However, CYP2C19*2 and its seven linked SNPs were significantly associated with lower NorEND concentrations, MRNorEND/NDDM and MRNorEND/(Z)-END. Specifically, patients carrying the CYP2C19*2 variant allele A had significantly lower NorEND concentrations [median (range), GG vs. GA vs. AA: 1.51 (0.38­3.28) vs. 1.28 (0.30­3.36) vs. 1.15 ng ml−1 (0.26­2.45, P = 0.010)] as well as significantly lower MRNorEND/(Z)-END [GG vs. GA vs. AA: 9.40 (3.27­28.35) vs. 8.15 (2.67­18.9) vs. 6.06 (4.47­14.6), P < 0.0001] and MRNorEND/NDDM [GG vs. GA vs. AA: 2.75 (0.62­6.26) vs. 2.43 (0.96­4.18) vs. 1.75 (1.10­2.49), P < 0.00001]. CYP2C19 H2 haplotype, which included CYP2C19*2, was also significantly associated with lower NorEND concentrations (P = 0.0020), MRNorEND/NDDM (P < 0.0001) and MRNorEND/(Z)-END (P < 0.0001), indicating significantly lower formation rates of NorEND. CONCLUSION: These data highlight the potential relevance of CYP2C19 pharmacogenetics in influencing NorEND concentrations in tamoxifen-treated patients, which may influence treatment outcomes.


Assuntos
Antineoplásicos Hormonais/farmacocinética , Neoplasias da Mama/metabolismo , Citocromo P-450 CYP2C19/genética , Tamoxifeno/análogos & derivados , Tamoxifeno/farmacocinética , Adulto , Idoso , Antineoplásicos Hormonais/sangue , Antineoplásicos Hormonais/uso terapêutico , Povo Asiático , Biotransformação , Neoplasias da Mama/tratamento farmacológico , Citocromo P-450 CYP2D6/genética , Feminino , Frequência do Gene , Haplótipos , Voluntários Saudáveis , Humanos , Desequilíbrio de Ligação , Pessoa de Meia-Idade , Polimorfismo Genético/genética , Polimorfismo de Nucleotídeo Único , Tamoxifeno/sangue , Tamoxifeno/uso terapêutico
15.
Nature ; 466(7309): 935-40, 2010 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-20686482

RESUMO

Despite the success of genomics in identifying new essential bacterial genes, there is a lack of sustainable leads in antibacterial drug discovery to address increasing multidrug resistance. Type IIA topoisomerases cleave and religate DNA to regulate DNA topology and are a major class of antibacterial and anticancer drug targets, yet there is no well developed structural basis for understanding drug action. Here we report the 2.1 A crystal structure of a potent, new class, broad-spectrum antibacterial agent in complex with Staphylococcus aureus DNA gyrase and DNA, showing a new mode of inhibition that circumvents fluoroquinolone resistance in this clinically important drug target. The inhibitor 'bridges' the DNA and a transient non-catalytic pocket on the two-fold axis at the GyrA dimer interface, and is close to the active sites and fluoroquinolone binding sites. In the inhibitor complex the active site seems poised to cleave the DNA, with a single metal ion observed between the TOPRIM (topoisomerase/primase) domain and the scissile phosphate. This work provides new insights into the mechanism of topoisomerase action and a platform for structure-based drug design of a new class of antibacterial agents against a clinically proven, but conformationally flexible, enzyme class.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , DNA Girase/química , Quinolinas/química , Quinolinas/farmacologia , Staphylococcus aureus/enzimologia , Inibidores da Topoisomerase II , Antibacterianos/metabolismo , Apoenzimas/química , Apoenzimas/metabolismo , Arginina/metabolismo , Ácido Aspártico/metabolismo , Sítios de Ligação , Domínio Catalítico , Ciprofloxacina/química , Ciprofloxacina/metabolismo , Cristalografia por Raios X , DNA/química , DNA/metabolismo , Clivagem do DNA , DNA Girase/metabolismo , DNA Super-Helicoidal/química , DNA Super-Helicoidal/metabolismo , Desenho de Fármacos , Resistência a Medicamentos , Escherichia coli/enzimologia , Manganês/metabolismo , Modelos Moleculares , Conformação Proteica , Quinolinas/metabolismo , Quinolonas/química , Quinolonas/metabolismo , Relação Estrutura-Atividade
16.
J Biol Chem ; 289(26): 17980-95, 2014 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-24782313

RESUMO

Malaria is a preventable and treatable disease; yet half of the world's population lives at risk of infection, and an estimated 660,000 people die of malaria-related causes every year. Rising drug resistance threatens to make malaria untreatable, necessitating both the discovery of new antimalarial agents and the development of strategies to identify and suppress the emergence and spread of drug resistance. We focused on in-development dihydroorotate dehydrogenase (DHODH) inhibitors. Characterizing resistance pathways for antimalarial agents not yet in clinical use will increase our understanding of the potential for resistance. We identified resistance mechanisms of Plasmodium falciparum (Pf) DHODH inhibitors via in vitro resistance selections. We found 11 point mutations in the PfDHODH target. Target gene amplification and unknown mechanisms also contributed to resistance, albeit to a lesser extent. These mutant parasites were often hypersensitive to other PfDHODH inhibitors, which immediately suggested a novel combination therapy approach to preventing resistance. Indeed, a combination of wild-type and mutant-type selective inhibitors led to resistance far less often than either drug alone. The effects of point mutations in PfDHODH were corroborated with purified recombinant wild-type and mutant-type PfDHODH proteins, which showed the same trends in drug response as the cognate cell lines. Comparative growth assays demonstrated that two mutant parasites grew less robustly than their wild-type parent, and the purified protein of those mutants showed a decrease in catalytic efficiency, thereby suggesting a reason for the diminished growth rate. Co-crystallography of PfDHODH with three inhibitors suggested that hydrophobic interactions are important for drug binding and selectivity.


Assuntos
Antimaláricos/química , Inibidores Enzimáticos/química , Malária Falciparum/parasitologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Plasmodium falciparum/enzimologia , Plasmodium falciparum/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Antimaláricos/farmacologia , Sítios de Ligação , Cristalografia por Raios X , Di-Hidro-Orotato Desidrogenase , Avaliação Pré-Clínica de Medicamentos , Resistência a Medicamentos , Inibidores Enzimáticos/farmacologia , Humanos , Malária Falciparum/tratamento farmacológico , Modelos Moleculares , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/química , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Mutação Puntual , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo
17.
Eur J Clin Pharmacol ; 70(2): 155-66, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24193570

RESUMO

PURPOSE: This exploratory study was aimed at elucidating the pharmacogenetics of regulatory nuclear receptors (PXR, CAR, RXRα and HNF4α) and their implications on docetaxel pharmacokinetics and pharmacodynamics in local Chinese nasopharyngeal cancer patients. METHODS: A total of 59 single nucleotide polymorphisms (SNPs), including tag-SNPs and functionally relevant SNPs of the genes encoding these regulatory nuclear receptors (PXR/NR1I2, CAR/NR1I3, RXRα/NR2B1 and HNF4α/NR2A1), were profiled in the patients enrolled in our study by direct sequencing (N = 50). The generalized linear model was employed to estimate the haplotypic effects on the pharmacokinetics and pharmacodynamics of the patients. RESULTS: The pharmacokinetic profiles of docetaxel in these patients were characterized by marked interindividual variability, with approximately four- to sixfold variations observed in Cmax, AUC0-∞ and CL. Individual SNP association tests revealed that polymorphisms in NR2B1 and NR2A1 were significantly correlated with altered docetaxel pharmacokinetics. Subsequent haplotype association analysis identified the NR2B1 LD block 2 AG haplotype [*+4458G>A(rs3132291) and *+4988A>G(rs4842198)] to be significantly associated with altered pharmacokinetics, in which patients carrying two copies of the AG haplotype had approximately a 20 % decreased Cmax and AUC0-∞ and a 21 % increased CL compared to those who carried only one copy or no copies of the haplotype. A number of SNPs in NR1I2, NR1I3, NR2B1 and NR2A1 were also associated with a significant decrease in blood counts from baseline. No haplotype was found to exert any effects on the pharmacodynamics parameters. CONCLUSIONS: The present exploratory study identified several SNPs in the genes encoding regulatory nuclear receptors which may account for the interpatient variability in docetaxel pharmacokinetics and pharmacodynamics. These findings highlight the important role of regulatory nuclear receptors on the disposition of docetaxel.


Assuntos
Antineoplásicos/farmacocinética , Neoplasias Nasofaríngeas/genética , Neoplasias Nasofaríngeas/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Taxoides/farmacocinética , Adulto , Idoso , Antineoplásicos/sangue , Antineoplásicos/farmacologia , Povo Asiático/genética , Carcinoma , Receptor Constitutivo de Androstano , Docetaxel , Feminino , Haplótipos , Hemoglobinas/análise , Humanos , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Carcinoma Nasofaríngeo , Contagem de Plaquetas , Polimorfismo de Nucleotídeo Único , Taxoides/sangue , Taxoides/farmacologia
18.
Eval Program Plann ; 97: 102247, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36739744

RESUMO

The evaluation of crop research institutes in the developing world under limited data availability has not been assessed in the past due to resource constraints. The paper assesses the social benefits of rice research taking the case of a research institute from India following a new approach. The area coverage of the varieties was estimated to be 3.4 million ha and the gain in production was 6.2 million tonnes per year in India. The additional return obtained due to the adoption of these varieties was about ₹ 14,621 million (US$ 232 million) per year at constant 2014-5 prices. The return per rupee investment in the institute's research and extension was ₹ 17. This approach is recommended for the impact evaluation of other crop research institutes in India and the developing world under resource constraints.


Assuntos
Academias e Institutos , Humanos , Avaliação de Programas e Projetos de Saúde , Índia
19.
Front Cell Infect Microbiol ; 13: 1130101, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37153145

RESUMO

Background: New multi-purpose prevention technology (MPT) products are needed to prevent human immunodeficiency virus (HIV) and herpes simplex virus type 2 (HSV2). In this study, we evaluated a fast-dissolve insert that may be used vaginally or rectally for prevention of infection. Objective: To describe the safety, acceptability, multi-compartment pharmacokinetics (PK), and in vitro modeled pharmacodynamics (PD) after a single vaginal dose of an insert containing tenofovir alafenamide (TAF) and elvitegravir (EVG) in healthy women. Methods: This was a Phase I, open-label, study. Women (n=16) applied one TAF (20mg)/EVG (16mg) vaginal insert and were randomized (1:1) to sample collection time groups for up to 7 days post dosing. Safety was assessed by treatment-emergent adverse events (TEAEs). EVG, TAF and tenofovir (TFV) concentrations were measured in plasma, vaginal fluid and tissue, and TFV-diphosphate (TFV-DP) concentration in vaginal tissue. PD was modeled in vitro by quantifying the change in inhibitory activity of vaginal fluid and vaginal tissue against HIV and HSV2 from baseline to after treatment. Acceptability data was collected by a quantitative survey at baseline and post treatment. Results: The TAF/EVG insert was safe, with all TEAEs graded as mild, and acceptable to participants. Systemic plasma exposure was low, consistent with topical delivery, while high mucosal levels were detected, with median TFV vaginal fluid concentrations exceeding 200,000 ng/mL and 1,000 ng/mL for up to 24 hours and 7 days post dosing, respectively. All participants had vaginal tissue EVG concentrations of > 1 ng/mg at 4 and 24 hours post dosing. The majority had tissue TFV-DP concentrations exceeding 1000 fmol/mg by 24 - 72 hours post dosing. Vaginal fluid inhibition of HIV-1 and HSV-2 in vitro significantly increased from baseline and was similarly high at 4 and 24 hours post dosing. Consistent with high tissue TFV-DP concentrations, p24 HIV antigen production from ectocervical tissues infected ex vivo with HIV-1 significantly decreased from baseline at 4 hours post dosing. HSV-2 production from tissue also decreased post treatment. Conclusions: A single dose of TAF/EVG inserts met PK benchmarks, with PK data supporting an extended window of high mucosal protection. PD modeling supports mucosal protection against both HIV-1 and HSV-2. The inserts were safe and highly acceptable. Clinical trial registration: ClinicalTrials.gov, identifier NCT03762772.


Assuntos
Fármacos Anti-HIV , Infecções por HIV , HIV-1 , Humanos , Feminino , Fármacos Anti-HIV/efeitos adversos , Tenofovir/efeitos adversos , Alanina
20.
Plants (Basel) ; 12(6)2023 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-36987051

RESUMO

Bacterial blight (BB) is a devastating disease of rice in the tropics of Indian sub-continent, where the presence of Xoo races with varying levels of genetic diversity and virulence renders disease management extremely challenging. In this context, marker-assisted improvement of plant resistance has been proven as one of the most promising approaches for the development of sustainable rice cultivars. The present study demonstrates the marker-assisted introgression of the three BB resistant genes (Xa21 + xa13 + xa5) into the background of HUR 917, a popular aromatic short grain (ASG) rice cultivar in India. The performance of the resulting improved products (near isogenic lines (NILs), HR 23-5-37-83-5, HR 23-5-37-121-10, HR 23-5-37-121-14, HR 23-65-6-191-13, HR 23-65-6-237-2, HR 23-65-6-258-10 and HR 23-65-6-258-21) establishes the utility of marker-assisted selection (MAS) approach for accelerated trait introgression in rice. The MAS-bred lines carrying three introgressed genes showed broad spectrum BB resistance (lesion length, LL of 1.06 ± 1.35 cm to 4.61 ± 0.87 cm). Besides, these improved lines showed the complete product profile of recurrent parent HUR 917 along with the enhanced level of durable BB resistance. The improved introgression lines with durable BB resistance would contribute to sustainable rice production in India, particularly in the Indo-Gangetic plane that has substantial acreage under HUR 917.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA