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Carotenoid cleavage oxygenases (CCOs) enzymes play a vital role in plant growth and development through the synthesis of apocarotenoids and their derivative. These chemicals are necessary for flower and fruit coloration, as well as the manufacture of plant hormones such as abscisic acid (ABA) and strigolactones, which control a variety of physiological processes. The CCOs gene family has not been characterized in Arachis hypogaea. Genome mining of A. hypogaea identifies 24 AhCCO gene members. The AhCCO gene family was divided into two subgroups based on the recent study of the Arabidopsis thaliana CCO gene family classification system. Twenty-three AhCCO genes, constituting 95.8% of the total, were regulated by 29 miRNAs, underscoring the significance of microRNAs (miRNAs) in governing gene expression in peanuts. AhCCD19 is the only gene that lacks a miRNA target site. The physicochemical characteristics of CCO genes and their molecular weights and isoelectric points were studied further. The genes were then characterized regarding chromosomal distribution, structure, and promoter cis-elements. Light, stress development, drought stress, and hormone responsiveness were discovered to be associated with AhCCO genes, which can be utilized in developing more resilient crops. The investigation also showed the cellular location of the encoded proteins and discovered that the peanut carotenoid oxygenase gene family's expansion was most likely the result of tandem, segmental, and whole-genome duplication events. The localization expresses the abundance of genes mostly in the cytoplasm and chloroplast. Expression analysis shows that AhCCD7 and AhCCD14 genes show the maximum expression in the apical meristem, lateral leaf, and pentafoliate leaf development, while AhNCED9 and AhNCED13 express in response to Aspergillus flavus resistance. This knowledge throws light on the evolutionary history of the AhCCO gene family and may help researchers better understand the molecular processes behind gene duplication occurrences in plants. An integrated synteny study was used to find orthologous carotenoid oxygenase genes in A. hypogaea, whereas Arabidopsis thaliana and Beta vulgaris were used as references for the functional characterization of peanut CCO genes. These studies provide a foundation for future research on the regulation and functions of this gene family. This information provides valuable insights into the genetic regulation of AhCCO genes. This technology could create molecular markers for breeding programs to develop new peanut lines.
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Arachis , Regulación de la Expresión Génica de las Plantas , Familia de Multigenes , Oxigenasas , Estrés Fisiológico , Arachis/genética , Arachis/enzimología , Estrés Fisiológico/genética , Oxigenasas/genética , Oxigenasas/metabolismo , Carotenoides/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Filogenia , Genoma de Planta , Regiones Promotoras Genéticas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
We report a series of isomeric, dicationic Re(bpy2+)(CO)3I complexes with bpy (2,2'-bipyridine) modified by two phenyl-CH2-(NMe3)+ pendants with cations located at variable distances from the active site for electrocatalytic CO2 reduction in CH3CN/2.8 M H2O. The position of the cationic groups dramatically increases the rate of catalysis by â¼800-fold, from 1.2 to 950 s-1, with only a minor increase in overpotential. Acceleration is due to stabilization of the initial CO2 adduct and lowering of ΔG for C-OH bond cleavage by Coulombic stabilization of anionic charges. Performance may be enhanced by accumulation in the electrochemical double layer. Transition state stabilization in the optimized isomer unlocks the low overpotential "protonation-first" pathway, highlighting the sizable effects of subtle structural optimization.
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The reaction steps for the selective conversion of a transition metal carbonyl complex to a hydroxymethyl complex that releases methanol upon irradiation with visible light have been successfully quantified in acetonitrile solution with dihydrobenzimidazole organic hydride reductants. Dihydrobenzimidazole reductants have been shown to be inactive toward H2 generation in the presence of a wide range of proton sources and have been regenerated electrochemically or photochemically. Specifically, the reaction of cis-[Ru(bpy)2(CO)2]2+ (bpy = 2,2'-bipyridine) with one equivalent of a dihydrobenzimidazole quantitatively yields a formyl complex, cis-[Ru(bpy)2(CO)(CHO)]+, and the corresponding benzimidazolium on a seconds time scale. Kinetic experiments revealed a first-order dependence on the benzimidazole hydride concentration and an unusually large kinetic isotope effect, inconsistent with direct hydride transfer and more likely to occur by an electron transfer-proton-coupled electron transfer (EΤ-PCET) or related mechanism. Further reduction/protonation of cis-[Ru(bpy)2(CO)(CHO)]+ with two equivalents of the organic hydride yields the hydroxymethyl complex cis-[Ru(bpy)2(CO)(CH2OH)]+. Visible light excitation of cis-[Ru(bpy)2(CO)(CH2OH)]+ in the presence of excess organic hydride was shown to yield free methanol. Identification and quantification of methanol as the sole CO reduction product was confirmed by 1H NMR spectroscopy and gas chromatography. The high selectivity and mild reaction conditions suggest a viable approach for methanol production from CO, and from CO2 through cascade catalysis, with renewable organic hydrides that bear similarities to Nature's NADPH/NADP+.
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The adoption of green chemistry protocols in nanoparticle (NP) synthesis has exhibited substantial potential and is presently a central focus in research for generating versatile NPs applicable across a broad spectrum of applications. In this scientific contribution, we, for the first time, examined the ability of Aconitum Laeve (A. Laeve) crude extract to synthesize silver and gold nanoparticles (AgNPs@AL; AuNP@AL) and explored their potential applications in biological activities and the catalytic degradation of environmental pollutants. The synthesized NPs exhibited a distinctive surface plasmon resonance pattern, a spherical morphology with approximate sizes of 5-10 nm (TEM imaging), a crystalline architecture (XRD analysis), and potential functional groups identified by FTIR spectroscopy. The antibacterial activity was demonstrated by inhibition zones that measured 16 and 14 mm for the AgNPs@AL and AuNP@AL at a concentration of 80 µg/mL against Staphylococcus aureus and 14 and 12 mm against Escherichia coli, respectively. The antioxidant potential of the synthesized NPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-Oxide (PTIO), and 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. Our findings suggest that the AuNP@AL effectively countered the tested radicals considerably, displaying IC50 values of 115.9, 103.54, and 180.85 µg/mL against DPPH, PTIO, and ABTS, respectively. In contrast, the AgNPs@AL showed IC50 values of 144.9, 116.36, and 95.39 µg/mL against the respective radicals. In addition, both the NPs presented significant effectiveness in the photocatalytic degradation of methylene blue and rhodamine B. The overall observations indicate that A. Laeve possesses a robust capability to synthesize spherical nanoparticles, exhibiting excellent dispersion and showcasing potential applications in both biological activities and environmental remediation.
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Aconitum , Antibacterianos , Antioxidantes , Oro , Nanopartículas del Metal , Extractos Vegetales , Plata , Nanopartículas del Metal/química , Plata/química , Oro/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Aconitum/química , Antibacterianos/farmacología , Antibacterianos/química , Antibacterianos/síntesis química , Catálisis , Antioxidantes/química , Antioxidantes/farmacología , Antioxidantes/síntesis química , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus/efectos de los fármacos , Tecnología Química Verde , Escherichia coli/efectos de los fármacosRESUMEN
A dicationic Re bipyridine-type complex, fac-Re(6,6'-(2-((trimethylammonio)-methyl)phenyl)-2,2'-bipyridine )(CO)3Cl hexafluorophosphate (12+), has been synthesized, and its electrochemical behavior under Ar and CO2 has been investigated. The presence of pendent tetra-alkylammonium cations induces an anodic shift in the electrocatalytic potential for CO2 reduction relative to structurally similar model complexes. The electrochemical mechanisms in anhydrous CH3CN and in the presence of weak acids (water or trifluoroethanol) have been analyzed using cyclic voltammetry assisted by infrared spectroelectrochemistry and theoretical calculations. The dication enables catalysis at a diminished potential through Coulombic stabilization of the doubly reduced pentacoordinate species, its CO2 adduct, the hydroxide anion, and the conjugate base formed during acid-assisted C-OH bond cleavage of the metallocarboxylic acid to the metallocarbonyl and H2O. The major reduction product is CO, but in the presence of trifluoroethanol, formate is also produced with 14% Faradaic efficiency.
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Alcohol dehydrogenases (ADH) are a family of enzymes that catalyse the interconversion between ketones/aldehydes and alcohols in the presence of NADPH cofactor. It is challenging to desymmetrise the substituted cyclopentane-1,3-dione by engineering an ADH, while the reaction mechanism of the metal independent ADH remains elusive. Here we measured the conversion of a model substrate 2-benzyl-2-methylcyclopentane-1,3-dione by LbADH and found it predominately gave the (2R,3R) product. Binding mode analysis of the substrate in LbADH from molecular dynamics simulations disclosed the origin of the enantioselectivity of the enzyme; the opening and closing of the loop 191-205 above the substrate are responsible for shaping the binding pocket to orientate the substrate, so as to give different stereoisomer products. Using QM/MM calculations, we elucidated the reaction mechanism of LbADH. Furthermore, we demonstrated the reaction profile corresponding to the production of different stereoisomers, which is in accordance with our experimental observations. This research here will shed a light on the rational engineering of ADH to achieve stereodivergent stereoisomer products.
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Alcohol Deshidrogenasa , Alcoholes , Alcohol Deshidrogenasa/química , Aldehídos , Catálisis , Cetonas/química , Especificidad por SustratoRESUMEN
To increase its operational stability and ongoing reusability, B. subtilis pectinase was immobilized on iron oxide nanocarrier. Through co-precipitation, magnetic iron oxide nanoparticles were synthesized. Scanning electron microscopy (SEM) and energy dispersive electron microscopy (EDEX) were used to analyze the nanoparticles. Pectinase was immobilized using glutaraldehyde as a crosslinking agent on iron oxide nanocarrier. In comparison to free pectinase, immobilized pectinase demonstrated higher enzymatic activity at a variety of temperatures and pH levels. Immobilization also boosted pectinase's catalytic stability. After 120 h of pre-incubation at 50 °C, immobilized pectinase maintained more than 90% of its initial activity due to the iron oxide nanocarrier, which improved the thermal stability of pectinase at various temperatures. Following 15 repetitions of enzymatic reactions, immobilized pectinase still exhibited 90% of its initial activity. According to the results, pectinase's catalytic capabilities were enhanced by its immobilization on iron oxide nanocarrier, making it economically suitable for industrial use.
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Enzimas Inmovilizadas , Nanopartículas de Magnetita , Enzimas Inmovilizadas/metabolismo , Estabilidad de Enzimas , Glutaral , Poligalacturonasa/metabolismo , Concentración de Iones de Hidrógeno , Nanopartículas Magnéticas de Óxido de Hierro , Temperatura , CinéticaRESUMEN
Mercury (Hg) is a widespread environmental pollutant and toxicant that induces multiple organ damage in humans and animals. Hg toxicity is mediated by the induction of oxidative stress in the target cells. We used uric acid (UA), a potent antioxidant found in biological fluids, to protect human red blood cells (RBC) and lymphocytes against Hg-mediated cell, organelle, and genotoxicity. RBCs were incubated with mercuric chloride (HgCl2), an Hg(II) compound, either alone or in the presence of UA. Incubation of RBCs with only HgCl2 increased the production of nitrogen and oxygen radical species, enhanced methemoglobin levels, heme degradation, free ferrous iron, oxidation of proteins and membrane lipids, and reduced the antioxidant capacity of cells. UA enhanced the antioxidant capacity of RBCs and restored metabolic, plasma membrane-bound, and antioxidant enzyme activities. Scanning electron microscopy showed that UA prevented HgCl2-mediated morphological changes in RBCs. HgCl2 dissipated the mitochondrial membrane potential and increased lysosomal membrane damage in lymphocytes, but UA pre-treatment attenuated these effects. Genotoxicity analysis by comet assay showed that UA protected lymphocyte DNA from HgCl2-induced damage. Importantly, UA itself did not exhibit any deleterious effects on RBCs or lymphocytes. Thus, UA protects human blood cells from Hg(II)-mediated oxidative damage, reducing the harmful effects of this extremely toxic metal. We suggest that UA has a similar protective role in plasma against heavy metal toxicity.
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Mercurio , Ácido Úrico , Animales , Antioxidantes/metabolismo , Antioxidantes/farmacología , Daño del ADN , Eritrocitos , Humanos , Mercurio/metabolismo , Mercurio/toxicidad , Estrés Oxidativo , Ácido Úrico/metabolismo , Ácido Úrico/farmacologíaRESUMEN
BACKGROUND: Blueberry is one of the most important fruit crops worldwide. Anthocyanin is an important secondary metabolites that affects the appearance and nutritive quality of blueberries. However, few studies have focused on the molecular mechanism underlying anthocyanin accumulation induced by light intensity in blueberries. RESULTS: The metabolic analysis revealed that there were 134 significantly changed metabolites in the natural light compared to the control, and flavone, flavonol, and anthocyanins were the most significantly increased. Transcriptome analysis found 6 candidate genes for the anthocyanin synthesis pathway. Quantitative reverse transcription PCR (qRT-PCR) results confirmed changes in the expression levels of genes encoding metabolites involved in the flavonoid synthesis pathways. The flavonoid metabolic flux in the light intensity-treatment increased the accumulation of delphinidin-3-O-arabinoside compared to under the shading-treatment. Furthermore, we performed qRT-PCR analysis of anthocyanin biosynthesis genes and predicted that the gene of VcF3'5'H4 may be a candidate gene for anthocyanin accumulation and is highly expressed in light intensity-treated fruit. Through the co-expression analysis of transcription factors and anthocyanin synthesis pathway genes, we found that the VcbHLH004 gene may regulate VcF3'5'H4, and then we transformed VcbHLH004 heterologously into tomato to verify its function. CONCLUSION: These results provide novel insights into light intensity regulation of blueberry anthocyanin accumulation and represent a valuable data set to guide future functional studies and blueberry breeding.
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Arándanos Azules (Planta) , Vaccinium , Antocianinas/metabolismo , Arándanos Azules (Planta)/genética , Arándanos Azules (Planta)/metabolismo , Flavonoides/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Metaboloma , Vaccinium/genética , Vaccinium/metabolismoRESUMEN
The present study has been designed to devise a pen-side hematological formula for estimation of hemoglobin (Hb) from packed cell volume (PCV) in Cholistani breed of cattle being reared under pastoralism in Cholistan desert, Pakistan. It also aims to validate the soundness of rule of calculating Hb concentration as one-third of PCV and vice versa as being used in human medicine. Cholistani cattle (n = 364) were bled for PCV determination (microhematocrit) method and Hb estimation (hematology analyzer) (HbD) as well as through calculation being one-third of PCV (HbC). The independent-sample t-test was implied for deducing difference between HbD and HbC, and between HbD and corrected Hb (CHb) for all study groups. The CHb was deduced through regression prediction equation attained from linear regression model. Scatter-plots were drawn and linear regression was carried out between various studied hematological attributes. Significantly (P ≤ 0.01) positive correlation coefficient was noticed for all study groups being highest for female adult stock (r = 0.893; adjusted R-square = 0.79) between HbD and PCV and between HbD and HbC. The regression equation for overall results attained, i.e., Hb = 0.13 (PCV) + 6.3 was used to deduce CHb. A non-significant (P ≥ 0.05) difference was noticed between HbD and CHb. In conclusion, a convention of human clinical medicine that Hb concentration is third of PCV and vice versa cannot be implied for Cholistani cattle. A different equation, i.e., Hb (g/dL) = 0.13 (PCV) + 6.3 may provide reliable results for Hb estimation from the PCV in cattle.
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Cruzamiento , Hematócrito , Hemoglobinas , Animales , Bovinos , Femenino , Hematócrito/veterinaria , Hemoglobinas/análisis , PakistánRESUMEN
UTIs are majorly caused by species of bacteria in patients of almost all ages. The study was aimed to determine the prevalence rate of uropathogens, its antibiotic susceptibility pattern and associated risk factors. Urine samples were collected from n=470 participants using sterilized containers and were inoculated on culture media. The isolates were identified via gram-staining and biochemical characterization. A total of 43.20% samples were positive. Female contributed the highest prevalence rate, 78.82% as compared to male, 21.18%. The highest prevalence 40.90% was observed in the age-group 31-45, followed by 16-30 with 36.90%. Escherichia coli (47.80%) was the most prevalent, followed by Klebsiella pneumoniae (18.2%), Enterococcus faecalis (12.80%), Pseudomonas aeruginosa (10.30%) and Proteus mirabilis (7.40%). Staphylococcus aureus showed high sensitivity (100%) to amikacin, meropenem, imipenem, fosfomycin, vancomycin, clindamycin and linezolid while in case of E. faecalis, vancomycin and linezolid were highly potent. Amikacin and meropenem showed the highest (100%) potency followed by imipenem While Fosfomycin was highly potent to E. coli, K. pneumoniae, P. mirabilis and P. aeruginosa with potency rate 89.97%, 92.31%, 100% and 100% respectively. In the current study, the positivity rate was highly observed in female. E. coli and K. pneumoniae were found the most ubiquitous for UTI.
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Fosfomicina , Infecciones Urinarias , Amicacina , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Escherichia coli , Femenino , Humanos , Imipenem , Klebsiella pneumoniae , Linezolid , Masculino , Meropenem , Pseudomonas aeruginosa , Factores de Riesgo , Centros de Atención Terciaria , Infecciones Urinarias/tratamiento farmacológico , Infecciones Urinarias/epidemiología , Infecciones Urinarias/microbiología , VancomicinaRESUMEN
This perspective highlights the computational modelling of alkene and alkyne alkoxycarbonylation at palladium catalysts. We cover studies on Pd-catalysed alkoxycarbonylation of alkenes with bidentate diphosphine ligands, which reveal a hydride pathway is operating with an intermolecular alcoholysis step, where explicit solvation is mandatory to estimate the overall barriers correctly and model alcoholysis/copolymerisation selectivities. Subsequently, we discuss Pd-catalysed alkyne alkoxycarbonylation with P,N-chelating ligands, where an in situ base mechanism is operating involving ketene-type intermediates. We also discuss catalyst poisoning due to allene and designing a potential new catalyst tolerant towards allene poisoning.
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A promising bacterial strain for biodegrading dibutyl phthalate (DBP) was successfully isolated from activated sludge and characterized as a potential novel Microbacterium sp. USTB-Y based on 16S rRNA sequence analysis and whole genome average nucleotide identity (ANI). Initial DBP of 50 mg/L could be completely biodegraded by USTB-Y both in mineral salt medium and in DBP artificially contaminated soil within 12 h at the optimal culture conditions of pH 7.5 and 30 â, which indicates that USTB-Y has a strong ability in DBP biodegradation. Phthalic acid (PA) was identified as the end-product of DBP biodegraded by USTB-Y using GC/MS. The draft genome of USTB-Y was sequenced by Illumina NovaSeq and 29 and 188 genes encoding for putative esterase/carboxylesterase and hydrolase/alpha/beta hydrolase were annotated based on NR (non redundant protein sequence database) analysis, respectively. Gene3781 and gene3780 from strain USTB-Y showed 100% identity with dpeH and mpeH from Microbacterium sp. PAE-1. But no phthalate catabolic gene (pht) cluster was found in the genome of strain USTB-Y. The results in the present study are valuable for obtaining a more holistic understanding on diverse genetic mechanisms of PAEs biodegrading Microbacterium sp. strains.
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Dibutil Ftalato/metabolismo , Microbacterium/genética , Microbacterium/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biodegradación Ambiental , Genoma Bacteriano , Genómica , Microbacterium/clasificación , Microbacterium/aislamiento & purificación , Aguas del Alcantarillado/microbiologíaRESUMEN
Plant endophytes are microbes that colonize plant internal tissues and are ubiquitously associated with plants. In this study, seven endophytic bacterial strains, 665L2, 725L2, 725R2, 92R2, 728R3, 728R4 and 2416T3, were isolated from seeds of five healthy maize varieties (Zea mays L.) and all identified as Bacillus velezensis by polyphasic taxonomy based on 16S rRNA and gyrA gene phylogenetic analysis. In addition, according to the genotyping results from random amplified polymorphic DNA (RAPD), 665L2, 725L2, 725R2 and 92R2 belonged to the same strain, while 728R3 and 2416T3 belonged to another strain. Pathogenic fungal strains 4, 5 and 6 were isolated from three diseased maize varieties (Zea mays L.), and they were identified as Talaromyces funiculosus, Penicillium oxalicum and Fusarium verticillioides, respectively, by polyphasic taxonomy based on morphological identification, ITS rDNA and bio-control gene phylogenetic analyses. Seven endophytic bacterial Bacillus velezensis strains had favourable antagonistic activity, and antagonistic testing was carried out against the three pathogenic strains, Talaromyces funiculosus 4, Penicillium oxalicum 5 and Fusarium verticillioides 6. Biological control lipopeptide antibiotic genes (bioA, bmyB, ituC, fenD, srfAA, srfAB, yngG and yndJ) were amplified using specific primers, and they were found in the seven endophytic bacterial Bacillus velezensis strains. This study provides a scientific basis for future research on the use of resistant endophytic bacterial resources to enhance crop production.
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Catalytic methoxycarbonylation of ethene with a bidentate tertiary phosphine (DTBPX) and palladium has been explored at the B3PW91-D3/PCM level of density functional theory. Three different pathways for formation of methyl propanoate (MePro) have been studied, namely carbomethoxy (A), ketene (B) and hydride-hydroxyalkylpalladium pathways (C), the latter of which is favoured because it has the lowest overall kinetic barrier. After intermolecular methanolysis, a hydroxyalkylpalladium complex has been characterised on pathway C, which eventually leads to the low overall barrier to produce MePro. The possibility of copolymerisation leading to oligo-/polymers has also been considered. With a computed selectivity of >99% towards the formation of MePro and a reasonably low overall kinetic barrier of 23.0 kcal mol-1, pathway C appears to be the most plausible one. Consistent with experimental data, the overall barrier increases to 30.1 kcal mol-1 for a less bulky bidentate phosphine.
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Tuberculosis (TB) is a global issue as one-third of the population worldwide is considered to be infected. TB has become a critical public health problem as a result of increasing drug resistance, which poses a challenge to current control strategies. Similar to environmental factors, genetic makeup of the host equally contributes to disease onset. We performed genotypic analysis to examine the relationship between IFNG and TB onset and drug resistance in a Pakistani population comprising 689 subjects. Notable differences were observed in the IFNG polymorphism (+874T/A) between the case and control groups. The frequency of the wild-type genotype (TT) in the controls (43.2%) was significantly higher than in the cases (25.3%) (odds ratio [OR] = 0.77, p < 0.0001), while the mutant genotype frequency (AA) (38.57%) in the cases was significantly higher than in the controls (22.6%) (OR = 1.46, p < 0.0001). The heterozygous genotype frequency (TA) did not significantly differ between the control and case groups. Compared with the controls, the variant allele (A) was approximately twice as frequent in the cases. Females and older people have a higher chance of disease development. Finally, the IFNG (+874T/A) polymorphism was not associated with drug sensitivity or resistance. However, a genotypic polymorphism of IFNG (+874T/A) was significantly associated with susceptibility to TB, and the T allele conferred protection against TB. Additional studies involving larger cohorts are needed to further explore this relationship between genetics and disease vulnerability.
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Predisposición Genética a la Enfermedad , Interferón gamma/genética , Polimorfismo de Nucleótido Simple , Tuberculosis/epidemiología , Tuberculosis/genética , Adolescente , Adulto , Anciano , Niño , Farmacorresistencia Bacteriana , Femenino , Estudios de Asociación Genética , Genotipo , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Pakistán/epidemiología , Fenotipo , Vigilancia de la Población , Tuberculosis/diagnóstico , Adulto JovenRESUMEN
In the palladium-catalysed methoxycarbonylation of technical propyne, the presence of propadiene poisons the hemilabile Pd(P,N) catalyst. According to density functional theory calculations (B3PW91-D3/PCM level), a highly stable π-allyl intermediate is the reason for this catalyst poisoning. Predicted regioselectivities suggest that at least 11 % of propadiene should yield this allyl intermediate, in which the reaction gets stalled under the turnover conditions due to an insurmountable methanolysis barrier of 25.8â kcal mol-1 . The results obtained for different ligands and substrates are consistent with the available experimental data. A new ligand, (6-Cl-3-Me-Py)PPh2 , is proposed, which is predicted to efficiently control the branched/linear selectivity, avoiding rapid poisoning (with only 0.2 % of propadiene being trapped as the Pd allyl complex), and to tremendously increase the catalytic activity by decreasing the overall barrier to 9.1â kcal mol-1 .
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A revised in situ base mechanism of alkyne alkoxycarbonylation via a Pd catalyst with hemilabile P,N-ligands (PyPPh2, Py = 2-pyridyl) has been fully characterised at the B3PW91-D3/PCM level of density functional theory. Key intermediates on this route are acryloyl and η3-propen-1-oyl complexes that readily undergo methanolysis. With two hemilabile P,N-ligands and one or both of them protonated, the overall computed barrier is 16.8 kcal mol-1. This new mechanism is consistent with all of the experimental data relating to substituent effects on relative reaction rates and branched/linear selectivities, including new results on the methoxycarbonylation of phenylacetylene using (4-Me2N-Py)PPh2 and (6-Cl-Py)PPh2 ligands. This ligand is found to decrease catalytic activity over PyPPh2, thus invalidating a formerly characterised in situ base mechanism.
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This study describes the first ever utilization of cell free aqueous extract of cyanobacterium Leptolyngbya JSC-1 as a source of strong reducing and stabilizing agents for the optimal biofabrication of gold nanoparticles (AuNPs) through an eco-friendly synthetic route. Well dispersed crystalline AuNPs of spherical morphology with a particle size of 100-200 nm were prepared. FTIR spectral analysis was then performed to characterize the possible functionalities of JSC-1 extract, mainly involved in stabilizing and formation of AuNPs. Based on the redox potential of JSC-1 extract, it was further confirmed that the extract provide a strong reducing environment in the reaction medium and causes reduction of gold ions. The resultant AuNPs were then explored to find out their photo-catalytic activity for methylene blue and antibacterial activities against E. coli (18 ± 2 mm) and S. aureus (14 ± 2 mm). It has been mechanistically identified that AuNPs caused bacterial membrane damage and cell disruption by inducing the production of intracellular reactive oxygen species (ROS). Together, these finding reveals that biochemically capped AuNPs are the promising antibacterial agents that induce oxidative stress in the two bacterial species evaluated and cause their membrane disruption leading to cell leakage and death.
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Antibacterianos/farmacología , Cianobacterias/metabolismo , Excipientes/farmacología , Oro/química , Nanopartículas del Metal/química , Antibacterianos/química , Bacterias/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Excipientes/química , Oro/farmacología , Tecnología Química Verde , Pruebas de Sensibilidad Microbiana , Nanotecnología/métodos , Oxidación-Reducción , Estrés Oxidativo/efectos de los fármacos , Tamaño de la Partícula , Especies Reactivas de Oxígeno/metabolismo , Staphylococcus aureus/efectos de los fármacosRESUMEN
OBJECTIVE:: Studies on diabetic foot ulcers (DFU) involving a representative sample of patients in Pakistan are scarce. This study aimed to determine baseline characteristics of infected DFUs in patients hospitalised at the Pakistan Institute of Medical Sciences Islamabad. METHOD:: In this cross-sectional study, carried out during May 2015 and June 2016, foot ulcer characteristics of patients with DFUs were investigated and documented. From infected DFUs, aerobic bacterial pathogens were isolated, identified and evaluated for antimicrobial susceptibility. RESULTS:: A total of 214 patients were recruited to the study, 62.6% of which were male, 90.2% were aged ≥40 years, 76.2% had type 1 diabetes and 78.5% had poor glycaemic control at time of presentation to hospital. Most patients had grade 3/moderate ulceration (based on the Wagner and International Working Group on the Diabetic Foot/Infectious Diseases Society of America criteria). Over half of the DFUs (57.9%) were of ≤3 months' duration and 70.1% were ≥3 cm2. Of the patients with deep infection grade ulcers, 26.6% underwent amputation, accounting for their prolonged hospital stay (≥20 days). Significant differences were observed between patients with type 1 and type 2 diabetes with DFUs in relation to gender (p≤0.0001), ulcer size (p=0.0421) and duration of hospital stay (p=0.0253). The most significant predictors for lower extremity amputation were osteomyelitis (p=0.0114), retinopathy (p=0.0001) and neuropathy (p=0.0001. Piperacillin/tazobactam was found to be an effective antibiotic against the most commonly isolated Staphylococcus non-aureus (35.48%), Pseudomonas aeruginosa (22.26%), and Staphylococcus aureus (20.96%) species indentified in the DFU infections. CONCLUSION:: The findings of this study may be helpful in the optimal management and appropriate treatment of patients with infected DFUs.