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1.
Biochimie ; 222: 72-86, 2024 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-38403043

RESUMO

Pyridoxal kinase (PdxK) is a vitamin B6 salvage pathway enzyme which produces pyridoxal phosphate. We have investigated the impact of PdxK deletion in Leishmania donovani on parasite survivability, infectivity and cellular metabolism. LdPdxK mutants were generated by gene replacement strategy. All mutants showed significant reduction in growth in comparison to wild type. For PdxK mediated biochemical perturbations, only heterozygous mutants and complementation mutants were used as the growth of null mutants were compromised. Heterozygous mutant showed reduction invitro infectivity and higher cytosolic and mitochondrial ROS levels. Glutathione levels decreased significantly in heterozygous mutant indicating its involvement in cellular oxidative metabolism. Pyridoxal kinase gene deletion resulted in reduced ATP levels in parasites and arrest at G0/G1 phase of cell cycle. All these perturbations were rescued by PdxK gene complementation. This is the first report to confirm that LdPdxK plays an indispensable role in cell survival, pathogenicity, redox metabolism and cell cycle progression of L. donovani parasites. These results provide substantial evidence supporting PdxK as a therapeutic target for the development of specific antileishmanial drug candidates.

2.
Acta Trop ; 252: 107139, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38307362

RESUMO

Clotrimazole is an FDA approved drug and is widely used as an antifungal agent. An extensive body of research is available about its mechanism of action on various cell types but its mode of killing of Leishmania donovani parasites is unknown. L. donovani causes Visceral Leishmaniasis which is a public health problem with limited treatment options. Its present chemotherapy is expensive, has adverse effects and is plagued with drug resistance issues. In this study we have explored the possibility of repurposing clotrimazole as an antileishmanial drug. We have assessed its efficacy on the parasites and attempted to understand its mode of action. We found that it has a half-maximal inhibitory concentration (IC50) of 35.75 ± 1.06 µM, 12.75 ± 0.35 µM and 73 ± 1.41 µM in promastigotes, intracellular amastigotes and macrophages, respectively. Clotrimazole is 5.73 times more selective for the intracellular amastigotes as compared to the mammalian cell. Effect of clotrimazole was reduced by ergosterol supplementation. It leads to impaired parasite morphology. It alters plasma membrane permeability and disrupts plasma membrane potential. Mitochondrial function is compromised as is evident from increased ROS generation, depolarized mitochondrial membrane and decreased ATP levels. Cell cycle analysis of clotrimazole treated parasites shows arrest at sub-G0 phase suggesting apoptotic mode of cell death.


Assuntos
Antiprotozoários , Leishmania donovani , Leishmaniose Visceral , Animais , Clotrimazol/farmacologia , Clotrimazol/metabolismo , Clotrimazol/uso terapêutico , Leishmaniose Visceral/tratamento farmacológico , Leishmaniose Visceral/parasitologia , Macrófagos , Pontos de Checagem do Ciclo Celular , Antiprotozoários/farmacologia , Antiprotozoários/uso terapêutico , Mamíferos
4.
3 Biotech ; 13(8): 266, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37425093

RESUMO

Leishmania donovani is the causative organism for visceral leishmaniasis. Although this parasite was discovered over a century ago, nothing is known about role of potassium channels in L. donovani. Potassium channels are known for their crucial roles in cellular functions in other organisms. Recently the presence of a calcium-activated potassium channel in L. donovani was reported which prompted us to look for other proteins which could be potassium channels and to investigate their possible physiological roles. Twenty sequences were identified in L. donovani genome and subjected to estimation of physio-chemical properties, motif analysis, localization prediction and transmembrane domain analysis. Structural predictions were also done. The channels were majorly α-helical and predominantly localized in cell membrane and lysosomes. The signature selectivity filter of potassium channel was present in all the sequences. In addition to the conventional potassium channel activity, they were associated with gene ontology terms for mitotic cell cycle, cell death, modulation by virus of host process, cell motility etc. The entire study indicates the presence of potassium channel families in L. donovani which may have involvement in several cellular pathways. Further investigations on these putative potassium channels are needed to elucidate their roles in Leishmania. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03692-y.

5.
Bioresour Technol ; 381: 129161, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37172745

RESUMO

In this study, a mild two-stage hydrothermal pretreatment was employed to optimally valorize industrial hemp (Cannabis sativa sp.) fibrous waste into sugars for Poly(3-hydroxybuyrate) (PHB) production using recombinant Escherichia coli LSBJ. Biomass was pretreated using hot water at 160, 180, and 200 °C for 5 and 10 min (15% solids), followed by disk refining. The sugar yields during enzymatic hydrolysis were found to improve with increasing temperature and the yields for hot water-disk refining pretreatment (HWDM) were higher compared to only hot water pretreatment at all conditions. The maximum glucose (56 g/L) and cellulose conversion (92%) were achieved for HWDM at 200 °C for 10 min. The hydrolysate obtained was fermented at a sugar concentration of 20 g/L. The PHB inclusion and concentration of 48% and 1.8 g/L, respectively, were similar to those from pure sugars. A pH-controlled fermentation resulted in a near bi-fold increase in PHB yield (3.46 g/L).


Assuntos
Cannabis , Resíduos Industriais , Carboidratos , Fermentação , Açúcares , Água , Hidrólise
6.
Microb Pathog ; 178: 106082, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36958644

RESUMO

The hexose monophosphate shunt is a crucial pathway in a variety of microorganisms owing to its vital metabolic products and intermediates such as NADPH, ribose 5-phosphate etc. The enzyme 6-phosphogluconolactonase catalyses the second step of this pathway, converting 6-phosphogluconolactone to 6-phosphogluconic acid. This enzyme has been known to have a significant involvement in growth, pathogenesis and sensitivity to oxidative stress in bacterial and protozoal pathogens. However, the functional role of kinetoplastid Leishmania donovani 6-phospohogluconolactonase (Ld6PGL) remains unexplored. L. donovani is the second largest parasitic killer and causative organism of life threatening visceral leishmaniasis. To understand its possible functional role in the parasite, the alleles of Ld6PGL were sequentially knocked-out followed by gene complementation. The Ld6PGL mutant cell lines showed decrease in transcriptional and translational expression as well as in the enzyme activity. In case of Ld6PGL null mutants, approximately 2-fold reduction was observed in growth. The null mutants also showed ∼38% decrease in infectivity, which recovered to ∼15% on complementation. Scanning electron microscopy showed a marked decrease in flagellar length in the knockout parasites. When treated with the standard drug miltefosine, the mutant strains had no significant change in the drug sensitivity. However, the Ld6PGL mutants were more susceptible to oxidative stress. Our findings suggest that 6PGL is required for parasite growth and infection, but it is not essential.


Assuntos
Hidrolases de Éster Carboxílico , Leishmania donovani , Animais , Leishmania donovani/fisiologia , Leishmaniose Visceral/parasitologia , Estresse Oxidativo , Hidrolases de Éster Carboxílico/metabolismo
7.
Trans R Soc Trop Med Hyg ; 117(2): 67-71, 2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36283121

RESUMO

Visceral l eishmaniasis (VL), also known as kala-azar, had once been targeted for elimination in 2020, which now has been shifted to 2030. The year 2020 was also the year in which the world was gripped by the coronavirus disease 2019 (COVID-19) pandemic. This review sheds light on the impact of COVID-19 on VL elimination programmes and the increasing incidences of COVID-19/VL cases. Lockdowns were imposed worldwide that led to the suspension of surveys, active case finding and mass drug administration, which are important activities to manage neglected tropical diseases. Healthcare machinery was redirected to control the pandemic and acute resource shortages were seen. Budget cuts from funding agencies and donors also came as a severe blow. Priority changes for manufacturers of drugs and diagnostic kits have also exacerbated the situation. Cases where patients were co-infected with VL and COVID-19 were reported across various settings and in people of various age groups, posing unprecedented challenges in diagnosis and treatment. Concerted efforts from all stakeholders are required to understand and deal with the impact that this pandemic has had on VL.


Assuntos
COVID-19 , Leishmaniose Visceral , Humanos , Leishmaniose Visceral/epidemiologia , Leishmaniose Visceral/tratamento farmacológico , Pandemias , Controle de Doenças Transmissíveis , COVID-19/epidemiologia , Administração Massiva de Medicamentos , Doenças Negligenciadas/epidemiologia , Doenças Negligenciadas/tratamento farmacológico , Índia/epidemiologia
8.
Biochimie ; 202: 212-225, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36037881

RESUMO

The enzymes of the pentose phosphate pathway are vital to survival in kinetoplastids. The second step of the pentose phosphate pathway involves hydrolytic cleavage of 6-phosphogluconolactone to 6-phosphogluconic acid by 6- phosphogluconolactonase (6PGL). In the present study, Leishmania donovani 6PGL (Ld6PGL) was cloned and overexpressed in bacterial expression system. Comparative sequence analysis revealed the conserved sequence motifs, functionally and structurally important residues in 6PGL family. In silico amino acid substitution study and interacting partners of 6PGL were predicted. The Ld6PGL enzyme was found to be active in the assay and in the parasites. Specificity was confirmed by Western blot analysis. The ∼30 kDa protein was found to be a dimer in MALDI, glutaraldehyde crosslinking and size exclusion chromatography studies. Kinetic analysis and structural stability studies of Ld6PGL were performed with denaturants and at varied temperature. Computational 3D Structural modelling of Ld6PGL elucidates that it has a similar α/ß hydrolase fold structural topology as in other members of 6PGL family. The three loops are found in extended form when the structure is compared with the human 6PGL (Hs6PGL). Further, enzyme substrate binding mode and its mechanism were investigated using the molecular docking and molecular simulation studies. Interesting dynamics action of substrate 6-phosphogluconolactone was observed into active site during MD simulation. Interesting differences were observed between host and parasite enzyme which pointed towards its potential to be explored as an antileishmanial drug target. This study forms the basis for further analysis of the role of Ld6PGL in combating oxidative stress in Leishmania.


Assuntos
Hidrolases de Éster Carboxílico , Leishmania donovani , Proteínas de Protozoários , Cinética , Leishmania donovani/enzimologia , Leishmania donovani/genética , Simulação de Acoplamento Molecular , Via de Pentose Fosfato , Hidrolases de Éster Carboxílico/genética , Proteínas de Protozoários/genética
9.
ChemMedChem ; 17(16): e202200109, 2022 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-35638162

RESUMO

A Core-Linker-Polyamine (CLP) strategy has been exploited to develop new antileishmanial agents. It involves the linker-based assembly of alkyl-polyamine side chain as a potential pharmacophore motif with a privileged heterocyclic motif, 4-arylquinoline. A series of aminoalkyl 4-arylquinoline-2-carboxamides and their analogs were synthesized and tested against L. donovani promastigotes. Among all synthesized derivatives, 10 compounds showed significant antipromastigote activities with more efficacy (IC50 : 4.75-8 µM) than an antileishmanial oral drug Miltefosine (IC50 : 8.9±1.55 µM). Most active aminoalkyl-quinoline-carboxamides 9 a and 9 b, displayed negligible cytotoxicity towards human monocytic (THP-1) macrophages. The compounds show antileishmanial activity by generating mitochondrial superoxide radicals. However, they did not show interference with trypanothione reductase, a redox enzyme of Leishmania. Significant change in the morphology of the L. donovani promastigote by the compounds was observed. The Structure-activity relationship analysis suggest the pharmacophoric importance of alkylpolyamine and carboxamide motifs. In silico evaluation indicated that the investigated active molecules 9 a and 9 b possess important drug-likeness, physicochemical and pharmacokinetic-relevant properties.


Assuntos
Antiprotozoários , Leishmania donovani , Leishmania , Antiprotozoários/química , Antiprotozoários/farmacologia , Humanos , Estresse Oxidativo , Poliaminas/farmacologia , Relação Estrutura-Atividade
10.
Bioresour Technol ; 344(Pt A): 126193, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34710613

RESUMO

In this review article, discuss the many ways utilized by the dairy sector to treat pollutants, emphasizing their influence on the quality and efficiency with which contamination is removed. It focuses on biotechnology possibilities for valorizing dairy waste in particular. The findings revealed that dairy waste may be treated using physicochemical, biological, and biotechnological techniques. Notably, this article highlighted the possibility of dairy waste being used as a feedstock not only for the generation of biogas, bioethanol, biohydrogen, microbial fuel cells, lactic acid, and fumaric acid via microbial technology but also for the production of biooil and biochar by pyrolysis. In addition, this article critically evaluates the many treatment techniques available for recovering energy and materials from dairy waste, their combinations, and implementation prospects. Valorization of dairy waste streams presents an opportunity to extend the dairy industry's presence in the fermented functional beverage sector.


Assuntos
Fontes de Energia Bioelétrica , Biocombustíveis , Biotecnologia
11.
Proteins ; 90(3): 747-764, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34708889

RESUMO

The bilobal protein kinase-like fold in pseudokinases lack one or more catalytic residues, conserved in canonical protein kinases, and are considered enzymatically deficient. Tertiary structures of pseudokinases reveal that their loops topologically equivalent to activation segments of kinases adopt contracted configurations, which is typically extended in active conformation of kinases. Herein, anisotropic network model based normal mode analysis (NMA) was conducted on 51 active conformation structures of protein kinases and 26 crystal structures of pseudokinases. Our observations indicate that although backbone fluctuation profiles are similar for individual kinase-pseudokinase families, low intensity mean square fluctuations in pseudo-activation segment and other sub-structures impart rigidity to pseudokinases. Analyses of collective motions from functional modes reveal that pseudokinases, compared to active kinases, undergo distinct conformational transitions using the same structural fold. All-atom NMA of protein kinase-pseudokinase pairs from each family, sharing high amino acid sequence identities, yielded distinct community clusters, partitioned by residues exhibiting highly correlated fluctuations. It appears that atomic fluctuations from equivalent activation segments guide community membership and network topologies for respective kinase and pseudokinase. Our findings indicate that such adaptations in backbone and side-chain fluctuations render pseudokinases competent for catalysis-independent roles.


Assuntos
Proteínas Quinases/química , Sequência de Aminoácidos , Domínio Catalítico , Bases de Dados de Proteínas , MAP Quinases Reguladas por Sinal Extracelular/química , Quinases Associadas a Receptores de Interleucina-1/química , Quinases de Proteína Quinase Ativadas por Mitógeno/química , Ligação Proteica , Conformação Proteica , Relação Estrutura-Atividade
12.
Environ Sci Pollut Res Int ; 29(1): 1401-1412, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34350578

RESUMO

The present study was conducted to investigate the residue status of two insecticides (acetamiprid and buprofezin) and their dissipation kinetics in three matrices viz. paddy grain, straw, and soil. The extraction procedure for residues of these two insecticides was executed using acetonitrile solvent. The analytical method was validated, which showed good linearity with the limit of quantification (LOQ) value of 0.01 and 0.02 mg kg-1 for acetamiprid and buprofezin, respectively. The recovery range was 79.67-98.33 % concerning all the matrices in both the insecticides. Acetamiprid (20% SP) and Buprofezin (25% SC) were applied separately in the paddy field in two doses: single dose (recommended dose) and double dose along with untreated control throughout the experiment. Residue analysis of these two insecticides in paddy (grain and straw) and soil was accomplished employing high-performance liquid chromatography (HPLC) with ultraviolet (UV) detector and confirmed by ultra-performance liquid chromatography (UPLC) coupled with mass spectrometry (UPLC-MS/MS). The dissipation data showed that acetamiprid exhibited higher dissipation in comparison with buprofezin. However, their persistence was found slightly higher in soil. The dissipation dynamics in the rice and soil were discussed with biological half-lives of both the insecticides. Consumer risk assessment study was also made considering its fate to the consumers.


Assuntos
Inseticidas , Resíduos de Praguicidas , Poluentes do Solo , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Meia-Vida , Inseticidas/análise , Cinética , Neonicotinoides , Resíduos de Praguicidas/análise , Solo , Poluentes do Solo/análise , Espectrometria de Massas em Tandem , Tiadiazinas
13.
J Chromatogr A ; 1648: 462208, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34000594

RESUMO

Public exposure to pesticides through tobacco has attracted serious attention. Here we report a simultaneous screening and quantitation method for the non-target multiresidue analysis of pesticides in different tobacco types. The method involved extraction of a homogenate (20 g, containing 2 g tobacco) in ethyl acetate (10 mL), cleanup of 2 mL extract by dispersive solid phase extraction with PSA (50 mg)+C18 (50 mg)+GCB (25 mg)+MgSO4 (100 mg), followed by reconstitution in 1 mL acetonitrile:water (3:7) and analysis using HPLC with Quadrupole-Orbitrap mass spectrometry. The high resolution accurate mass analysis was performed through sequential full-scan (resolution=35000) and variable data independent acquisition (resolution=17500) events. When the method was evaluated in a mixture of 181 pesticides, it effectively minimised matrix interferences and false negatives. The target compounds included 5 pairs of isomers and 27 pairs of isobars, which were distinguished based on chromatographic separation, mass resolving power and/or unique product ions. The screening detection limit (SDL) for 86.4% of the test pesticides was set at 5 ng/g, while the remainder had the SDLs at 10 ng/g (9.3%) and 40 ng/g (4.3%). Nearly, 75% of the compounds showed recoveries of 70-120% at 10 ng/g. The rest of the compounds showed satisfactory recoveries at 40 and 100 ng/g. In all cases, precision-RSDs were < 20%. The established method demonstrated a successful performance in four different types of tobacco matrices while aligning with the guidelines of SANTE and US-FDA. Owing to its efficiency, the method is recommended for screening and quantitation of multiclass pesticides in tobacco.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Limite de Detecção , Praguicidas/análise , Extração em Fase Sólida/métodos , Produtos do Tabaco/análise
14.
Acta Trop ; 220: 105922, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33878308

RESUMO

Visceral Leishmaniasis is a major neglected tropical disease with increasing incidences of drug resistance. This has led to the search for a suitable drug target for chemotherapeutic intervention. Potassium channels are a family of membrane proteins which play a vital role in homeostasis and any perturbation in them alters cell survival which makes them an attractive target. To characterize a calcium-activated potassium channel from Leishmania donovani (LdKCa), a putative ion-channel like protein which showed sequence similarity with other Trypanosoma cruzi putative potassium channels was selected. It was cloned and expressed with a histidine tag. MALDI confirmed that it is a potassium channel. Homology model of LdKCa was generated by I-TASSER. It is a transmembrane protein localized in the plasma membrane as predicted by DeepLoc tool. In silico analyses of the protein showed that it is a small conductance calcium activated potassium channel. Point mutation in conserved signature domain 'TXGYGD' affects the protein function as predicted by heat map analysis. The LdKCa model predicted amino acids S207, T208 and M236 as ligand-binding sites. The sequence HSLRGRSARVIQLAWRLRKARKVGPHAPSLKQKVYTLVLSWLLT was the highest scoring B-cell epitope. The highest scoring T-cell epitope was RLYSVIVYL. This study may provide new insights into antigenicity features of leishmanial calcium-activated potassium channels.


Assuntos
Leishmaniose Visceral/imunologia , Canais de Potássio Cálcio-Ativados/imunologia , Animais , Sítios de Ligação , Cálcio/metabolismo , Cálcio/uso terapêutico , Membrana Celular , Simulação por Computador , Humanos , Leishmania donovani , Canais de Potássio Cálcio-Ativados/genética , Mapas de Interação de Proteínas , Linfócitos T/imunologia
15.
Colloids Surf B Biointerfaces ; 203: 111729, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33836370

RESUMO

Biofilm formation on medical implants and devices has been a severe concern that results in their impaired performance and life-threatening complications. Thus, development of novel functional coatings for infection prone surfaces with biofilm inhibiting characteristics is of prime significance considering the rapid emergence of multidrug resistant bacteria. Herein we present a novel nanocomposite derived from Graphene Oxide (GO) and a newly developed functional Ionic liquid (IL) obtained through a metathesis reaction between a triarylmethane dye hexamethyl pararosaniline chloride or crystal violet (CV) and sodium dodeceyl sulfate (SDS) to yield [CV][DS] (hexamethyl pararosaniline dodecyl sulfate). This highly biocompatible [CV][DS]-GO nanocomposite exhibit more than four times improved antibacterial activity in comparison to bare GO against both gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). As suggested by XRD, FTIR and UV absorption and SEM results improved activity of [CV][DS]-GO nanocomposite is ascribed to the synergistic effect of reduced nanocomposite sheet thickness, enhanced amphiphilicity imparted by dodecylsulfate (DS), exposed active ArN+ groups of CV and some inherent functionalities of GO. This is also complemented by the ruptured and diffused S. aureus cell walls as observed in bacterial SEM result. In contrast, the nanocomposites of the precursors with GO do not demonstrate any significant antibacterial effect. Coatings developed using GO upon infestation with E. coli revealed significant biofilm formation after 48 and 72 h of incubation while [CV][DS]-GO coated surface demonstrated no colony growth under similar circumstances. Thus, [CV][DS]-GO nanocomposite coatings exhibit excellent resistance to bacterial growth even up to 72 h incubation signifying its bactericidal effect. Therefore, the developed nanocomposite may be considered as one of the improved antibacterial wash resistant coating material for biomedical devices and surfaces susceptible to to biofilm formation.


Assuntos
Grafite , Líquidos Iônicos , Nanocompostos , Antibacterianos/farmacologia , Escherichia coli , Testes de Sensibilidade Microbiana , Prata , Staphylococcus aureus
16.
Clin Rheumatol ; 40(4): 1575-1579, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33174109

RESUMO

The COVID-19 pandemic has led to major changes in clinical practice on a global scale in order to protect patients. This includes the identification of vulnerable patients who should "shield" in order to reduce the likelihood of contracting SARS-CoV2. We used national specialty guidance and an adapted screening tool to risk stratify patients identified from our prescribing and monitoring databases, and identify those needing to shield (score ≥ 3) using information from departmental letters, online general practice records and recent laboratory investigations. We collated underlying rheumatological conditions and risk factors. Two months into the shielding process, we examined the COVID-19 status of these patients using hospital laboratory records and compared to population level data. Of 887 patients assessed, 248 (28%) scored ≥ 3 and were sent a standard shielding letter. The most common risk factor in the shielding letter group was age ≥ 70 years and/or presence of a listed co-morbidity (199 patients). The most common rheumatology conditions were rheumatoid arthritis (69.4%), polymyalgia rheumatica (8.5%) and giant cell arteritis (8.5%). Coronavirus incidence rates were similar in the shielding letter group (0.403%) and in the UK population (0.397%). However, we found a trend towards lower incidence (0.113%) in our whole cohort (RR 0.28, 95%CI 0.04-2.01 for the whole cohort compared to UK population). The trend towards lower incidence in this cohort could be because of prior education regarding general infection risk and response to public health messages. While risk stratification and shielding could be effective, prior education regarding general infection risk and public health messages to enhance health protection behaviours during a pandemic may have equal or more important roles. Key Points • Patients on treatment for rheumatic disorders showed a trend for lower incidence of COVID-19 transmission irrespective of shielding letter status • This could potentially be because of prior education regarding infection risk received when starting on disease-modifying medication • Health education influencing health protection behaviours may be of equal or more importance than shielding information in reducing transmission of SARS-CoV-2.


Assuntos
Antirreumáticos/uso terapêutico , COVID-19/epidemiologia , Educação em Saúde/métodos , Doenças Reumáticas/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , COVID-19/prevenção & controle , Estudos de Coortes , Comorbidade , Feminino , Humanos , Incidência , Masculino , Saúde Pública , Reumatologistas/estatística & dados numéricos , Fatores de Risco , Reino Unido/epidemiologia
17.
Microorganisms ; 8(8)2020 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-32824090

RESUMO

Enterococcus faecalis is one of the major causes of urinary tract infection, showing acquired resistance to various classes of antimicrobials. The objective of this study was to determine the prevalence of drug resistance and its genetic determinants for E. faecalis clinical isolates in north-central Bangladesh. Among a total of 210 E. faecalis isolates, isolated from urine, the resistance rates to erythromycin, levofloxacin, and gentamicin (high level) were 85.2, 45.7, and 11.4%, respectively, while no isolates were resistant to ampicillin, vancomycin and teicoplanin. The most prevalent resistance gene was erm(B) (97%), and any of the four genes encoding aminoglycoside modifying enzyme (AME) were detected in 99 isolates (47%). The AME gene aac(6')-Ie-aph(2")-Ia was detected in 46 isolates (21.9%) and was diverse in terms of IS256-flanking patterns, which were associated with resistance level to gentamicin. Tetracycline resistance was ascribable to tet(M) (61%) and tet(L) (38%), and mutations in the quinolone resistance-determining region of both GyrA and ParC were identified in 44% of isolates. Five isolates (2.4%) exhibited non-susceptibility to linezolide (MIC, 4 µg/mL), and harbored the oxazolidinone resistance gene optrA, which was located in a novel genetic cluster containing the phenicol exporter gene fexA. The optrA-positive isolates belonged to ST59, ST902, and ST917 (CC59), while common lineages of other multiple drug-resistant isolates were ST6, ST28, CC16, and CC116. The present study first revealed the prevalence of drug resistance determinants of E. faecalis and their genetic profiles in Bangladesh.

18.
Proteins ; 88(12): 1620-1638, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32667690

RESUMO

Protein Kinase-Like Non-Kinases (PKLNKs), commonly known as "pseudokinases", are homologous to eukaryotic Ser/Thr/Tyr protein kinases (PKs) but lack the crucial aspartate residue in the catalytic loop, indispensable for phosphotransferase activity. Therefore, they are predicted to be "catalytically inactive" enzyme homologs. Analysis of protein-kinase like sequences from Arabidopsis thaliana led to the identification of more than 120 pseudokinases lacking catalytic aspartate, majority of which are closely related to the plant-specific receptor-like kinase family. These pseudokinases engage in different biological processes, enabled by their diverse domain architectures and specific subcellular localizations. Structural comparison of pseudokinases with active and inactive conformations of canonical PKs, belonging to both plant and animal origin, revealed unique structural differences. The currently available crystal structures of pseudokinases show that the loop topologically equivalent to activation segment of PKs adopts a distinct-folded conformation, packing against the pseudoenzyme core, in contrast to the extended and inhibitory geometries observed for active and inactive states, respectively, of catalytic PKs. Salt-bridge between ATP-binding Lys and DFG-Asp as well as hydrophobic interactions between the conserved nonpolar residue C-terminal to the equivalent DFG motif and nonpolar residues in C-helix mediate such a conformation in pseudokinases. This results in enhanced solvent accessibility of the pseudocatalytic loop in pseudokinases that can possibly serve as an interacting surface while associating with other proteins. Specifically, our analysis identified several residues that may be involved in pseudokinase regulation and hints at the repurposing of pseudocatalytic residues to achieve mechanistic control over noncatalytic functions of pseudoenzymes.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Genoma de Planta , Proteínas Quinases/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Domínio Catalítico , Modelos Moleculares , Fosforilação , Filogenia , Conformação Proteica , Proteínas Quinases/química , Proteínas Quinases/classificação , Proteínas Quinases/genética
20.
J AOAC Int ; 103(1): 23-39, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31462350

RESUMO

BACKGROUND: As a powerful antioxidant and natural colorant, anthocyanins are being used increasingly as a component of food supplements and nutraceutical products. Hence, its characterization is a prerequisite for further exploration of its nutraceutical potential. UV-Vis and MS are the two important techniques, which have been largely employed for the qualitative and quantitative determination of anthocyanins. However, a comprehensive review of the applications of these techniques in literature is scarce. OBJECTIVE: This paper aims to review the utilization of UV-Vis spectral data as well as mass spectral data for characterization and putative identification of anthocyanins with approaches of quantification. METHODS: The techniques described in literature have been thoroughly reviewed and comparatively evaluated. The complementary approaches of UV-Vis and MS spectra have been discussed for identification and quantification of these compounds. RESULTS: Valuable information about the chemical composition and structure of anthocyanins can be predicted from the UV-Vis spectral data, such as number and type of glycosylation as well as absence or presence of acylation, to name a few. It is also pointed out that for their structural confirmation, selectivity of mass detectors with unit and high-resolution analysis could be effective. CONCLUSIONS: The combination of LC-MS with UV-Vis spectroscopy provides complementary information on structural details of anthocyanins. In case the analytical reference standards are available, a triple quadrupole mass spectrometer provides selectivity and quantitative sensitivity in analysis. On the other hand, high-resolution MS analysis provides valuable information for tentative identification during nontarget screening of compounds when the reference standard is not available. HIGHLIGHTS: This paper reviews the applications of UV-Vis spectroscopy and LC-MS for qualitative and quantitative analysis of anthocyanins.


Assuntos
Antocianinas , Antocianinas/análise , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Espectrometria de Massas , Análise Espectral
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