Photostability and photodynamic antimicrobial profile of dye extracts from four (4) plants: prospects for eco-friendly low-cost food disinfection and topical biomedical applications.

In this study, photostability and photodynamic antimicrobial performance of dye extracts from Hibiscus sabdariffa (HS) calyces, Sorghum bicolor (SB) leaf sheaths, Lawsonia inermis (LI) leaves and Curcuma longa (CL) roots were investigated in Acetate-HCl (AH) Buffer (pH 4.6), Tris Base-HCl (TBH) Buffer (pH 8.6), distilled water (dH2O), and Phosphate Buffer Saline (PBS, pH 7.2) using Bacillus subtilis as model for gram positive bacteria, Escherichia coli as model for gram negative bacteria, phage MS2 as model for non-envelope viruses and phage phi6 as model for envelope viruses including SARS CoV-2 which is the causative agent of COVID-19. Our results showed that the photostability of the dye extracts is in the decreasing order of LI > CL > SB > HS. The dye extract-HS is photostable in dH2O but bleaches in buffers-AH, TBH and PBS. The rate of bleaching is higher in AH compared to in TBH and PBS. The bleaching and buffers affected the photodynamic and non-photodynamic antimicrobial activity of the dye extracts. The photodynamic antibacterial activity of the dye extracts is in the decreasing order of CL > HS > LI > SB while the non-photodynamic antibacterial activity is in the decreasing order of LI > CL > HS > SB. The non-photodynamic antiviral activity pattern observed is the same as that of non-photodynamic antibacterial activity observed. However, the photodynamic antiviral activity of the dye extracts is in the decreasing order of CL > LI > HS > SB. Given their performance, the dye extracts maybe mostly suitable for environmental applications including fresh produce and food disinfection, sanitation of hands and contact surfaces where water can serve as diluent for the extracts and the microenvironment is free of salts.

Antibiotic resistance and the COVID-19 pandemic: A dual crisis with complex challenges in LMICs.

Background and Aims: Antimicrobial resistance (AMR), a global health crisis of mounting urgency, has been further complicated by the ongoing COVID-19 pandemic. The intricate relationship between these two phenomena is especially pronounced in low- and middle-income countries (LMICs) due to the distinct obstacles encountered by their healthcare systems and policy structures. This study aims to explore the complex challenges arising from the coexistence of these two crises in LMICs and proffer specific recommendations for holistic management. Methods: An exhaustive bibliographic survey was executed, employing search queries in specialized databases such as PubMed, SCOPUS, and Web of Science's SCI-EXPANDED index. The timeframe for the literature search extended from January 2020 to January 2023. The search strategy employed key terms including antibiotic resistance, AMR, COVID-19 pandemic, low- and middle-income countries, SARS-CoV-2, and LMICs. Results: The pandemic has aggravated various drivers of AMR in LMICs, including limited capabilities, weak frameworks, and socioeconomic factors. New challenges have emerged, such as disruptions in the antibiotic supply chain and an increased risk of healthcare-associated infections. The interaction between these drivers presents a complex problem that demands a coordinated response. Specific recommendations include strengthening health systems, funding research and innovation, and enhancing infection prevention control measures. Conclusion: The coexistence of AMR and the COVID-19 pandemic in LMICs demands an integrated approach involving multiple stakeholders. Emphasis must be placed on constructing aligned regulatory frameworks, nurturing regional collaborations, and focusing on accessible therapeutic options. The study underscores the necessity for actionable strategies to achieve sustainable access to clean water and sanitation and also highlights the importance of long-term planning, funding, and specialized expertise in emerging modalities like phage therapy.

Women living with HIV in Nigeria: Predictive influence of hardiness on perceived stress.

Background: Women living with HIV experience severe HIV-related stress in sub-Saharan Africa. But evidence shows that individuals with high levels of the psychological hardiness characteristic who accept stressful situations as meaningful experience may withstand psychological stress. However, the literature on associations between hardiness and HIV-related stress among women living with HIV is scarce. The objective of this study was to investigate the relationship between hardiness and HIV-related stress among women living with HIV in Niger State, Nigeria.Methods: This study used a cross-sectional design. A systematic sampling technique was used to recruit 748 participants from three selected hospitals in Niger State. The perceived stress scale and the health-related hardiness scale were used for data collection. A total of 676 questionnaires were returned in usable form and were analysed using hierarchical regression analysis.Results: Pearson's correlation analysis showed that there is a statistically significant association between perceived stress and subscales of hardiness (p < 0.001). Hierarchical regression analysis results showed that hardiness significantly predicted perceived stress among the study sample with R2 = 0.286, F(3, 669) = 90, p < 0.001. Conclusion: The finding of this study that higher hardiness is associated with lower perceived stress suggests the potential helpfulness to women living with HIV of this personality for coping. The finding also suggests that nurses and other health care workers may facilitate the development and/or improvement of hardiness characteristics through cognitive behavioural interventions among women living with HIV to ameliorate HIV-related stress.

Relationships between anti-retroviral adherence, self-efficacy, and resilience among women living with HIV in Niger State, Nigeria.

The objectives of the study were to describe the level of self-efficacy and its relationship with resilience among women living with HIV in Niger State, Nigeria. Self-efficacy is an important predictor of treatment outcomes among people living with HIV. Using a systematic random sampling technique, 676 participants completed adherence self-efficacy and resilience measures from three selected hospitals in Niger State. The result showed high levels of self-efficacy among the participants, linear relationships between perceived stress and resilience (-.601), perceived stress and self-efficacy integration (-.504), perceived stress and self- efficacy perseverance (-.220), resilience and self-efficacy integration (.667) and resilience and self-efficacy perseverance (.377). Hierarchical multiple linear regression indicated that 48.3% of the variance in resilience was explained by the two sub -scales of self-efficacy (p = < .001). Also, 26% (p = < .001) of the variance in perceived stress was explained by the two subscales of the self-efficacy. It is concluded that self-efficacy is a significant predictor of resilience and perceived stress among women living with HIV in Niger State, Nigeria.

Stress and resilience among women living with HIV in Nigeria.

BACKGROUND: Psychological morbidities concurrent with HIV have been the focus of considerable scientific investigations. However, researchers have largely overlooked HIV-related stress and resilience among women living with HIV in rural communities. AIM: This study explored the associations between psychological resilience and HIV-related stress among women living with HIV. SETTING: The study was conducted in three randomly selected hospitals that provide primary HIV care in Niger state, Nigeria. METHODS: A predictive cross-sectional design was used to describe the relationship between perceived stress and resilience among the study population. RESULTS: Out of 748 participants who completed the Connor-Davidson resilience scale and the perceived stress scale questionnaires, 676 returned the questionnaire in usable form. While the results showed moderate levels of perceived stress and a high level of psychological resilience, there was a significant and negative relationship between HIV-related stress and psychological resilience (r = -0.601, p = 0.001). Also, higher resilience was significantly associated with decreased perceived stress. CONCLUSION: It is concluded that measures to promote resilience and employment opportunity may ameliorate HIV-related stress among women living with HIV.

Theoretical analyses on enantiospecificity of L-2-haloacid dehalogenase (DehL) from Rhizobium sp. RC1 towards 2-chloropropionic acid.

Dehalogenases continue to garner interest of the scientific community due to their potential applications in bioremediation of halogen-contaminated environment and in synthesis of various industrially relevant products. Example of such enzymes is DehL, an L-2-haloacid dehalogenase (EC 3.8.1.2) from Rhizobium sp. RC1 that catalyses the specific cleavage of halide ion from L-2-halocarboxylic acids to produce the corresponding D-2-hydroxycarboxylic acids. Recently, the catalytic residues of DehL have been identified and its catalytic mechanism has been fully elucidated. However, the enantiospecificity determinants of the enzyme remain unclear. This information alongside a well-defined catalytic mechanism are required for rational engineering of DehL for substrate enantiospecificity. Therefore, using quantum mechanics/molecular mechanics and molecular mechanics Poisson-Boltzmann surface area calculations, the current study theoretically investigated the molecular basis of DehL enantiospecificity. The study found that R51L mutation cancelled out the dehalogenation activity of DehL towards it natural substrate, L-2-chloropropionate. The M48R mutation, however introduced a new activity towards D-2-chloropropionate, conveying the possibility of inverting the enantiospecificity of DehL from L-to d-enantiomer with a minimum of two simultaneous mutations. The findings presented here will play important role in the rational design of DehL dehalogenase for improving substrate utility.

Genome-scale metabolic models as platforms for identification of novel genes as antimicrobial drug targets.

The growing number of multidrug-resistant pathogenic bacteria is becoming a world leading challenge for the scientific community and for public health. However, advances in high-throughput technologies and whole-genome sequencing of bacterial pathogens make the construction of bacterial genome-scale metabolic models (GEMs) increasingly realistic. The use of GEMs as an alternative platforms will expedite identification of novel unconditionally essential genes and enzymes of target organisms with existing and forthcoming GEMs. This approach will follow the existing protocol for construction of high-quality GEMs, which could ultimately reduce the time, cost and labor-intensive processes involved in identification of novel antimicrobial drug targets in drug discovery pipelines. We discuss the current impact of existing GEMs of selected multidrug-resistant pathogenic bacteria for identification of novel antimicrobial drug targets and the challenges of closing the gap between genome-scale metabolic modeling and conventional experimental trial-and-error approaches in drug discovery pipelines.

Deciphering the catalytic amino acid residues of l-2-haloacid dehalogenase (DehL) from Rhizobium sp. RC1: An in silico analysis.

The l-2-haloacid dehalogenases (EC 3.8.1.2) specifically cleave carbon-halogen bonds in the L-isomers of halogenated organic acids. These enzymes have potential applications for the bioremediation and synthesis of various industrial products. One such enzyme is DehL, the l-2-haloacid dehalogenase from Rhizobium sp. RC1, which converts the L-isomers of 2-halocarboxylic acids into the corresponding D-hydroxycarboxylic acids. However, its catalytic mechanism has not been delineated, and to enhance its efficiency and utility for environmental and industrial applications, knowledge of its catalytic mechanism, which includes identification of its catalytic residues, is required. Using ab initio fragment molecular orbital calculations, molecular mechanics Poisson-Boltzmann surface area calculations, and classical molecular dynamic simulation of a three-dimensional model of DehL-l-2-chloropropionic acid complex, we predicted the catalytic residues of DehL and propose its catalytic mechanism. We found that when Asp13, Thr17, Met48, Arg51, and His184 were individually replaced with an alanine in silico, a significant decrease in the free energy of binding for the DehL-l-2-chloropropionic acid model complex was seen, indicating the involvement of these residues in catalysis and/or structural integrity of the active site. Furthermore, strong inter-fragment interaction energies calculated for Asp13 and L-2-chloropropionic acid, and for a water molecule and His184, and maintenance of the distances between atoms in the aforementioned pairs during the molecular dynamics run suggest that Asp13 acts as the nucleophile and His184 activates the water involved in DehL catalysis. The results of this study should be important for the rational design of a DehL mutant with improved catalytic efficiency.

Multi-template homology-based structural model of L-2-haloacid dehalogenase (DehL) from Rhizobium sp. RC1.

Dehalogenases are of high interest due to their potential applications in bioremediation and in synthesis of various industrial products. DehL is an L-2-haloacid dehalogenase (EC 3.8.1.2) that catalyses the cleavage of halide ion from L-2-halocarboxylic acid to produce D-2-hydroxycarboxylic acid. Although DehL utilises the same substrates as the other L-2-haloacid dehalogenases, its deduced amino acid sequence is substantially different (<25%) from those of the rest L-2-haloacid dehalogenases. To date, the 3D structure of DehL is not available. This limits the detailed understanding of the enzyme's reaction mechanism. The present work predicted the first homology-based model of DehL and defined its active site. The monomeric unit of the DehL constitutes α/ß structure that is organised into two distinct structural domains: main and subdomains. Despite the sequence disparity between the DehL and other L-2-haloacid dehalogenases, its structural model share similar fold as the experimentally solved L-DEX and DehlB structures. The findings of the present work will play a crucial role in elucidating the molecular details of the DehL functional mechanism.

l-2-Haloacid dehalogenase (DehL) from Rhizobium sp. RC1.

l-2-Haloacid dehalogenase (DehL) from Rhizobium sp. RC1 is a stereospecific enzyme that acts exclusively on l-isomers of 2-chloropropionate and dichloroacetate. The amino acid sequence of this enzyme is substantially different from those of other l-specific dehalogenases produced by other organisms. DehL has not been crystallised, and hence its three-dimensional structure is unavailable. Herein, we review what is known concerning DehL and tentatively identify the amino acid residues important for catalysis based on a comparative structural and sequence analysis with well-characterised l-specific dehalogenases.