Cleavage of cell junction proteins as a host invasion strategy in leptospirosis.

Infection and invasion are the prerequisites for developing the disease symptoms in a host. While the probable mechanism of host invasion and pathogenesis is known in many pathogens, very little information is available on Leptospira invasion/pathogenesis. For causing systemic infection Leptospira must transmigrate across epithelial barriers, which is the most critical and challenging step. Extracellular and membrane-bound proteases play a crucial role in the invasion process. An extensive search for the proteins experimentally proven to be involved in the invasion process through cell junction cleavage in other pathogens has resulted in identifying 26 proteins. The similarity searches on the Leptospira genome for counterparts of these 26 pathogenesis-related proteins identified at least 12 probable coding sequences. The proteins were either extracellular or membrane-bound with a proteolytic domain to cleave the cell junction proteins. This review will emphasize our current understanding of the pathogenic aspects of host cell junction-pathogenic protein interactions involved in the invasion process. Further, potential candidate proteins with cell junction cleavage properties that may be exploited in the diagnostic/therapeutic aspects of leptospirosis will also be discussed. KEY POINTS: • The review focussed on the cell junction cleavage proteins in bacterial pathogenesis • Cell junction disruptors from Leptospira genome are identified using bioinformatics • The review provides insights into the therapeutic/diagnostic interventions possible.

Quality assurance of malaria rapid diagnostic tests: An aid in malaria elimination.

Background & objectives: India targets malaria elimination by 2030 in a phased manner, so malaria's assured diagnosis is crucial. Introduction of rapid diagnostic kits in India in 2010 has revolutionized malaria surveillance. The storage temperature of rapid diagnostic tests (RDTs), kit components and handling in transportations impact the results of RDTs. Therefore, quality assurance (QA) is required before it reaches end-users. The Indian Council of Medical Research-National Institute of Malaria Research (ICMR-NIMR) has a World Health Organization (WHO) recognized lot-testing laboratory facility to assure the quality of RDTs. Methods: The ICMR-NIMR receives RDTs from different manufacturing companies as well as various agencies such as National and State Programmes and Central Medical Services Society. The WHO standard protocol is followed to conduct all the tests, including long-term and post-dispatch testing. Results: A total of 323 lots tested during January 2014-March 2021 were received from different agencies. Amongst them, 299 lots passed the quality of test and 24 failed. In long-term testing, 179 lots were tested and only nine failed. A total of 7741 RDTs were received from end-users for post-dispatch testing of which 7540 qualified the QA test with a score of 97.4 per cent. Interpretation & conclusions: RDTs received for quality testing showed compliance with QA evaluation of malaria RDTs based on the protocol recommended by the WHO. However, continuous monitoring of the quality of RDTs is required under QA programme. Quality-assured RDTs have a major role, especially in areas where low parasitaemia of parasites persists.

Design and validation of multiplex polymerase chain reaction as a diagnostic tool for Plasmodium species.

BACKGROUND & OBJECTIVES: The highly sensitive method for a true understanding of malaria prevalence is of utmost importance for India's elimination strategy. The PCR reaction type with rapid detection, cost-effectiveness, and less workforce should be preferable. Multiplex PCR type accomplishes the present requirement by saving time and resources to find true surveillance data for malaria, especially in low-parasitemia/asymptomatic groups or populations. METHODS: The present study focuses on designing multiplex PCR (mPCR) to detect simultaneously Plasmodium genus (PAN) and two common Plasmodium species found in India. It is compared to standard nested PCR on 195 clinical samples to diagnose malaria. The mPCR was designed with a minimum number of primers, leading to less clogging and effective and enhanced detection. It contains one common reverse primer and three forward primers amplifying three targeted genes corresponding to P. falciparum, P. vivax, and Plasmodium genus. RESULTS: The sensitivity and specificity for mPCR were 94.06 and 95.74, respectively. The limit of detection for mPCR was 0.1 parasites/µl. The study has shown a ROC curve area for the mPCR of 0.949 for Plasmodium genus and P. falciparum and 0.897 for P. vivax with standard nPCR. INTERPRETATION & CONCLUSION: The mPCR is rapid in detecting species together, cost-effective, and requires fewer human resources than the standard nPCR. Therefore, the mPCR can be used as an alternative technique for the higher sensitive detection of the malaria parasite. It could also become a vital tool for determining malaria prevalence, facilitating the application of the most effective measures.

Sources and toxicological effects of metal and metalloids on human health through fish consumption in mineral-rich city, Ranchi, India.

Ranchi is the administrative capital of Jharkhand and is located in the southern part of the Chhotanagpur Plateau. It is rich in forest and mineral resources and hence is suitable for the establishment of many large- and small-scale industries. The estimated population of Ranchi for the year 2023 is 3.54 million. These demographic characteristics make the capital more vulnerable to environmental degradation. Also, previous water quality research focused on river, water, and oceans separately; however, little or no work has been carried out on the comparison of metal or metalloid analysis in rivers, waterfalls, and lakes. Hence, the present study aims to assess the pollution status of mineral-rich and industrial hub city, Ranchi, through analysis of metals or metalloids in abiotic (water and sediment) and biotic (fish and human) components. The water, sediment, and fish (Labeo rohita and Catla catla) samples were collected from Subarnarekha river, Jumar river, Dassam fall, Getalsud dam, Hundru fall, Jonha fall, Kanke dam, and Sita fall. Samples were collected following standard methods and analyzed in inductively coupled plasma mass spectrometry (ICP-MS). Among three aquatic systems (rivers, dams, and falls), dams were highly polluted with metals or metalloids, which may be due to effluent discharge from different industries. Additionally, the high population in the city also contributed to metals or metalloids pollution. The reason may be the direct sewage disposal and agricultural and surface runoff in the water systems. It was observed that most of the aquatic systems in Ranchi were severely polluted with metals or metalloids. The fish also accumulated these metals or metalloids in their body and can be life-threatening to the human population consuming them. The THQ (above 1) and HI (2.95) values for As showed that children are more vulnerable to health risk through consumption of contaminated fish. Hence, proper planning and management are needed to overcome the metals or metalloids pollution in Ranchi.

Comparative Assessment of Diagnostic Performance of Cytochrome Oxidase Multiplex PCR and 18S rRNA Nested PCR.

Malaria elimination and control require prompt and accurate diagnosis for treatment plan. Since microscopy and rapid diagnostic test (RDT) are not sensitive particularly for diagnosing low parasitemia, highly sensitive diagnostic tools are required for accurate treatment. Molecular diagnosis of malaria is commonly carried out by nested polymerase chain reaction (PCR) targeting 18S rRNA gene, while this technique involves long turnaround time and multiple steps leading to false positive results. To overcome these drawbacks, we compared highly sensitive cytochrome oxidase gene-based single-step multiplex reaction with 18S rRNA nested PCR. Cytochrome oxidase (cox) genes of P. falciparum (cox-III) and P. vivax (cox-I) were compared with 18S rRNA gene nested PCR and microscopy. Cox gene multiplex PCR was found to be highly specific and sensitive, enhancing the detection limit of mixed infections. Cox gene multiplex PCR showed a sensitivity of 100% and a specificity of 97%. This approach can be used as an alternative diagnostic method as it offers higher diagnostic performance and is amenable to high throughput scaling up for a larger sample size at low cost.

Chlorin e6 Conjugated Methoxy-Poly(Ethylene Glycol)-Poly(D,L-Lactide) Glutathione Sensitive Micelles for Photodynamic Therapy.

PURPOSE: In this study, we developed a polymeric micellar system for glutathione-mediated intracellular delivery of a photosensitizer, chlorin e6 (Ce6) by synthesizing an amphiphilic polymer, methoxy-poly(ethylene glycol)-poly(D,L-lactide)-disulfide-Ce6 (mPEG-PLA-S-S-Ce6), which self-assembled in aqueous environment to form micelles. METHODS: The polymer-drug conjugate was characterized by NMR. The singlet oxygen (2O1) generation and in vitro release of Ce6 micelles were evaluated. Further, glutathione-mediated intracellular drug delivery was assessed in human alveolar adenocarcinoma cells (A549), mouse mammary carcinoma cells (4 T1) and 3D A549 spheroids. RESULTS: The micellar system protected Ce6 from aggregation leading to improved 2O1 generation compared to free Ce6. Due to the availability of glutathione, the disulfide bonds in the micelles were cleaved resulting in rapid release of Ce6 evident from the in vitro study. The Ce6 micelles displayed quicker drug release in presence of glutathione monoester (GSH-OEt) pre-treated A549 and 4 T1 cells compared to without pre-treated cells. In vitro phototoxicity of micelles displayed enhanced toxicity in 10 mM GSH-OEt pre-treated A549 and 4 T1 cells compared to untreated cells. As anticipated, Ce6 micelles showed lower drug release in presence of 0.1 mM of buthionine sulfoximine (BSO) pretreated A549 and 4 T1 cells exhibiting lower phototoxicity. Further, A549 3D spheroids treated with Ce6 micelles showed significant inhibition in growth, enhanced phototoxicity, and cellular apoptosis in comparison to free Ce6. CONCLUSION: The above results showed that the developed strategy could be effective in improving the PDT efficacy of Ce6, and the developed polymeric micellar system could be utilized as a PDT regimen for cancer.

Transferrin-Modified Vitamin-E/Lipid Based Polymeric Micelles for Improved Tumor Targeting and Anticancer Effect of Curcumin.

PURPOSE: Transferrin receptor (TfR) is up-regulated in various malignant tumors not only to meet the iron requirement, but also to increase the cell survival via participation in various cellular signaling pathways. Here we explored transferrin as ligand for Poly(ethylene Glycol) (PEG)-ylated vitamin-E/lipid (PE) core micelles (VPM). METHODS: Transferrin modified polymer was synthesized and drug loaded micelles were evaluated in 2D Hela and HepG2 cancer cells for cellular uptake and cytotoxicity and in 3D Hela spheroids for growth inhibition, uptake and penetration studies. RESULTS: Targeted (Tf-VPM) and non-targeted (VPM) micelles showed mean hydrodynamic diameter of 114.2 ± 0.64 nm and 117.4 ± 0.72 nm and zeta potential was -22.8 ± 0.62 and -14.8 ± 1.74 mV, respectively. Cellular uptake study indicated that the Tf-CVPM were taken up by cancer cells (Hela and HepG2) with higher efficiency. Enhanced cytotoxicity was demonstrated for Tf-VPM compared to CVPM. Marked spheroid growth inhibition following treatment with Tf-CVPM was observed compared to the treatment with non-targeted CVPM. CONCLUSIONS: The developed transferrin-modified micelles have improved ability to solubilize the loaded drugs and could actively target solid tumors by its interaction with over-expressed transferrin receptors. Therefore, the nano-micelles could be further explored for its potential utilization in cancer therapy.

PRUNE is crucial for normal brain development and mutated in microcephaly with neurodevelopmental impairment.

PRUNE is a member of the DHH (Asp-His-His) phosphoesterase protein superfamily of molecules important for cell motility, and implicated in cancer progression. Here we investigated multiple families from Oman, India, Iran and Italy with individuals affected by a new autosomal recessive neurodevelopmental and degenerative disorder in which the cardinal features include primary microcephaly and profound global developmental delay. Our genetic studies identified biallelic mutations of PRUNE1 as responsible. Our functional assays of disease-associated variant alleles revealed impaired microtubule polymerization, as well as cell migration and proliferation properties, of mutant PRUNE. Additionally, our studies also highlight a potential new role for PRUNE during microtubule polymerization, which is essential for the cytoskeletal rearrangements that occur during cellular division and proliferation. Together these studies define PRUNE as a molecule fundamental for normal human cortical development and define cellular and clinical consequences associated with PRUNE mutation.

Isoproterenol-induced cardiac ischemia and fibrosis: Plant-based approaches for intervention.

Heart is the most active and incumbent organ of the body, which maintains blood flow, but due to various pathological reasons, several acute and chronic cardiac complications arise out of which myocardial infarction is one of the teething problems. Isoproterenol (ISP)-induced myocardial ischemia is a classical model to screen the cardioprotective effects of various pharmacological interventions. Phytochemicals present a novel option for treating various human maladies including those of the heart. A large number of plant products and their active ingredients have been screened for efficacy in ameliorating ISP-induced myocardial ischemia including coriander, curcumin, Momordica, quercetin, and Withania somnifera. These phytochemicals constituents may play key role in preventing disease and help in cardiac remodeling. Reactive oxygen species scavenging, antiinflammatory, and modulation of various molecular pathways such as Nrf2, NFкB, p-21 activated kinase 1 (PAK1), and p-smad2/3 signaling modulation have been implicated behind the claimed protection. In this review, we have provided a focused overview on the utility of ISP-induced cardiotoxicity, myocardial ischemia, and cardiac fibrosis for preclinical research. In addition, we have also surveyed molecular mechanism of various plant-based interventions screened for cardioprotective effect in ISP-induced cardiotoxicity, and their probable mechanistic profile is summarized.

Homocysteine and vitamin B12: Other causes of neural tube defects in Eastern Uttar Pradesh and Western Bihar population.

BACKGROUND: Neural tube defects (NTDs) are congenital malformations with an incidence of 1-10/1000 live births. Homocysteine and vitamin B12 metabolism have been shown to be associated with NTDs. AIM: To investigate the status of maternal and neonate's folic acid, homocysteine, and vitamin B12 levels and their association with the risk of development of NTDs in the population of Eastern Uttar Pradeshand Western Bihar, India. MATERIALS AND METHODS: This study is a cross-sectional, retrospective study where 96 mothers who either had a first NTD child or had a history of NTD child in the family and 126 neonates with spina bifida were recruited during the period 2012-2015. Eighty-four control mothers whose previous and current pregnancies were normal, and 87 control neonates who had no defects and were within the same age range as the NTD affected neonates, recruited from the department of pediatric surgery, were enrolled in the study. Plasma concentrations of folic acid, vitamin B12, and homocysteine were compared between cases and controls. RESULTS: The folic acid level in the mothers and neonates was within the normal limit. A significant increase in the level of homocysteine in mothers with affected pregnancy and in neonate cases in comparison to control mothers was obseved. Further, a significant decrease in the level of vitamin B12 in mothers with NTD neonates and in the affected neonates was noted. A negative correlation was found between homocysteine and vitamin B12 levels in case and control mothers. CONCLUSION: A correlation of an increase in serum homocysteine with a decrease in vitamin B12 was seen in mothers of neonates with NTD. A similar observation as made in the neonates with NTDs. It may be suggested that maternal decrease in vitamin B12, in mothers who have normal folic acid may be associated with NTD in their children.

Evaluation of Anti-Tumor Efficacy of Vorinostat Encapsulated Self-Assembled Polymeric Micelles in Solid Tumors.

Vorinostat (VOR), a potent HDAC inhibitor, suffers from low solubility and poor absorption, which hinders its successful application in therapy, especially in the treatment of solid tumors. In this study, an effort to improve the physicochemical characteristics of VOR was made by encapsulating it in PEG-PLGA copolymeric micelles. VOR-loaded PEG-PLGA micelles (VOR-PEG-PLGA) were produced by thin-film hydration and physicochemically characterized. The PEG-PLGA micelles had an average size of 124.06 ± 2.6 nm, polydispersity index of 0.27 ± 0.1, and entrapment efficiency of 90 ± 2.1%. Micelles were characterized by TEM, DSC, and drug release studies. The drug release occurred in a sustained manner up to 72 h from PEG-PLGA micelles. In the in vitro cell-based studies using human breast cancer (MDA MB 231) and murine melanoma (B16F10) cell lines, VOR-PEG-PLGA micelles exhibited superior cellular internalization, enhanced cytotoxic activity, and greater apoptosis compared to free drug. Percent cell killing of 54.9% for VOR-PEG-PLGA-treated cells was observed after 24 h compared to 36% for free VOR in MDA MB 231 cell line. Further, significant tumor suppression was witnessed in B16F10 tumor-bearing mice treated with VOR-PEG-PLGA micelles with a 1.78-fold reduction in tumor volume compared to free VOR-treated animals. Overall, the VOR-PEG-PLGA micelles improved the biopharmaceutical properties of VOR, which resulted in enhanced anti-tumor efficacy. Therefore, the newly developed nano-formulation of VOR could be considered as an effective treatment option in solid tumors.

Polylactide-Based Block Copolymeric Micelles Loaded with Chlorin e6 for Photodynamic Therapy: In Vitro Evaluation in Monolayer and 3D Spheroid Models.

Recently, photodynamic therapy (PDT) has found wide application as a noninvasive treatment modality for several cancers. However, the suboptimal delivery of photosensitizers (PSs) to the tumor site is a drawback, which inhibits the effectiveness of PDT. Hydrophobicity, strong oxygen and light dependence, and limited tissue penetrability of photosensitizers represent the major barriers to the clinical application of PDT. In order to improve biopharmaceutical properties of a clinically approved photosensitizer chlorin e6 (Ce6), we developed a nanoformulation encapsulating Ce6 in methoxy-poly(ethylene glycol)-poly(d,l-lactide) (mPEG-PLA) copolymeric micelles. The physicochemical properties, including particle size, zeta potential, encapsulation efficiency, drug loading, generation of reactive oxygen species following near-infrared light illumination (633 nm), and in vitro drug release, were determined. The therapeutic efficacy of Ce6-mPEG-PLA micelles following illumination were evaluated in vitro in both two- and three-dimensional cell culture systems by using human uterine cervix carcinoma (HeLa) and human alveolar adenocarcinoma (A549) cells in monolayers and in A549 spheroids, respectively. The mPEG-PLA micelles were stable with a particle size of 189.6 ± 14.32 nm and loaded Ce6 efficiently (encapsulation efficiency ∼75%). The Ce6-loaded micelles generated singlet oxygen at a higher concentration compared to free Ce6 in aqueous media. Ce6-mPEG-PLA micelle mediated PDT showed improved cellular internalization in both of the cell lines, resulting in enhanced cytotoxicity compared to free Ce6. In contrast, the Ce6-loaded micelles did not show any cytotoxicity in the absence of irradiation. The Ce6-loaded micelles exhibited deep penetration in the spheroids leading to phototoxicity and cellular apoptosis in the A549 spheroidal model. Results from this study indicated that the newly developed nanoformulation of Ce6 could be utilized in PDT as an effective treatment modality for solid tumors.

Curcumin Delivery by Poly(Lactide)-Based Co-Polymeric Micelles: An In Vitro Anticancer Study.

PURPOSE: This work describes the synthesis of block co-polymeric micelles, methoxy-poly(ethylene glycol)-poly(D,L-lactide) (mPEG-PLA) to encapsulate Curcumin (CUR), thereby improving the dispersibility and chemical stability of curcumin, prolonging its cellular uptake and enhancing its bioavailability. METHODS: CUR-mPEG-PLA micelles, was prepared using the thin-film hydration method and evaluated in vitro. The preparation process was optimized with a central composite design (CCD). Micelles were characterized by size, transmission electron microscopy, loading capacity, and critical micelle concentration (CMC). The cytotoxicity of CUR-mPEG-PLA micelles was investigated against murine melanoma cells, B16F10 and human breast cancer cells, MDA-MB-231. RESULTS: The average size of the CUR-mPEG-PLA micelles was 110 ± 5 nm with polydispersity index in the range of 0.15-0.31, and the encapsulating efficiency for CUR was 91.89 ± 1.2, and 11.06 ± 0.8% for drug-loading. Sustained release of CUR from micelles was observed with 9.73% CUR release from micelles compared to 64.24% release of free curcumin in first 6 h under sink condition. The CUR-mPEG-PLA was efficiently taken up by the cancer cells, B16F10 and MDA-MB-231. Following 24 h incubation, CUR-mPEG-PLA induced higher cytotoxicity compared to free CUR in MDA-MB-231 cell lines indicating exposure of higher dose of free CUR to cells lead to up-regulation of drug efflux mechanisms leading to decreased cell death in case of free CUR administration. CONCLUSION: Our results indicate that the proposed micellar system has the potential to serve as an efficient carrier for CUR by effectively solubilizing, stabilizing and delivering the drug in a controlled manner to the cancer cells.

Xanthan gum stabilized PEGylated gold nanoparticles for improved delivery of curcumin in cancer.

In recent years, gold nanoparticles (AuNPs) have received immense interest in various biomedical applications including drug delivery, photothermal ablation of cancer and imaging agent for cancer diagnosis. However, the synthesis of AuNPs poses challenges due to the poor reproducibility and stability of the colloidal system. In the present work, we developed a one step, facile procedure for the synthesis of AuNPs from hydrogen tetrachloroaurate (III) hydrate (HAuCl4. 3H2O) by using ascorbic acid and xanthan gum (XG) as reducing agent and stabilizer, respectively. The effect of concentrations of HAuCl4, 3H2O, ascorbic acid and methoxy polyethylene glycol-thiol (mPEG800-SH) were optimized and it was observed that stable AuNPs were formed at concentrations of 0.25 mM, 50 µM and 1 mM for HAuCl4.3H2O, ascorbic acid, and mPEG800-SH, respectively. The XG stabilized, deep red wine colored AuNPs (XG-AuNPs) were obtained by drop-wise addition of aqueous solution of ascorbic acid (50 mM) and XG (1.5 mg ml(-1)). Synthesized XG-AuNPs showed λmax at 540 nm and a mean hydrodynamic diameter of 80 ± 3 nm. PEGylation was performed with mPEG800-SH to obtain PEGylated XG-AuNPs (PX-AuNPs) and confirmed by Ellman's assay. No significant shift observed in λmax and hydrodynamic diameter between XG-AuNPs and PX-AuNPs. Colloidal stability of PX-AuNPs was studied in normal saline, buffers within a pH range of 1.2-7.4, DMEM complete medium and in normal storage condition at 4 ˚C. Further, water soluble curcumin was prepared using PVP-K30 as solid dispersion and loaded on to PX-AuNPs (CPX-AuNPs), and evaluated for cellular uptake and cytotoxicity in Murine melanoma (B16F10) cells. Time and concentration dependent studies using CPX-AuNPs showed efficient uptake and decreased cell viability compared to free curcumin.

A Narrative Review on Different Novel Machine Learning Techniques for Detecting Pathologies in Infants From Born Baby Cries.

This paper reviews the research work on the analysis and classification of pathological infant cries in the last 50 years. The literature review mainly covers the need and role of early clinical diagnosis, pathologies detected from cry samples, challenges in pathological cry signal data acquisition, signal processing techniques, and signal classifiers. The signal processing techniques include preprocessing, feature extraction from domains, such as time, spectral, time-frequency, prosodic, wavelet, etc, and feature selection for selecting dominant features. Literature covers traditional machine learning classifiers, such as Bayesian networks, decision trees, K-nearest neighbor, support vector machine, Gaussian mixture model, etc, and recently added neural network models, such as convolutional neural networks, regression neural networks, probabilistic neural networks, graph neural networks, etc. Significant experimental results of pathological cry identification and classification are listed for comparison. Finally, it suggests future research in the direction of database preparation, feature analysis and extraction, neural network classifiers to provide a non-invasive and robust automatic infant cry analysis model.

In-situ oil-spill remediation by an electrodeposited superhydrophobic copper mesh.

The present study aims to combat the problem of oil in water pollution via its separation using a superhydrophobic copper mesh. An ecofriendly superhydrophobic copper mesh with a water contact angle of 166 ± 2° is developed by a facile two-step process (electrodeposition followed by coating). The coated mesh with mechanical robustness, chemical endurance and thermal stability is a promising choice for real-world conditions. Additionally, its resistance to corrosion in harsh chemical environments ensures its long-term durability. With a separation efficiency of 99.9 %, the coated mesh serves as an efficient medium for oil-water separation. It can be used as a reusable filtering medium with high separation efficiency in alkali and neutral environments. Besides, it is also competent for continuous oil-water separation and collection of oil from wastewater. Thus, the above study clearly manifests that the coated mesh holds tremendous potential for large-scale oil spill cleanup.

In-situ assessment of the performance of oil-water separation by superhydrophobic coated cotton under extreme conditions.

The present study aims to address the issue of oil in water pollution by application of a superhydrophobic cotton fabric. The superhydrophobic cotton fabric with a water contact angle of 158 ± 2°, is developed by a solution immersion technique using zirconium dioxide (ZrO2) nanoparticles and hexadecyltrimethoxysilane. The synthesis parameters such as concentration, curing temperature, and immersion time were optimized using Box-Behnken design method. With mechanical durability, chemical resilience and thermal stability, the coated fabric can separate different oil-water mixtures with an efficiency of 99.9 %. The coated fabric can also be reused for 50 separation cycles in acidic and neutral medium. Besides, droplet dynamic behavior of oil-water mixture has also been studied to ascertain the effect of mixture impact velocities on separation performance. Additionally, coated fabric possesses self-cleaning feature, which makes it viable for muddy oil-water separation. Prepared coated fabric holds tremendous potential for industrial use and oil-water separation in extreme conditions.

Variability of the treated biomedical waste disposal behaviours during the COVID lockdowns.

Literature review suggests that studies on biomedical waste generation and disposal behaviors in North America are limited. Given the infectious nature of the materials, effective biomedical waste management is vital to the public health and safety of the residents. This study explicitly examines seasonal variations of treated biomedical waste (TBMW) disposal rates in the City of Regina, Canada, from 2013 to 2022. Immediately before the onset of COVID-19, the City exhibited a steady pattern of TBMW disposal rate at about 6.6 kg∙capita-1∙year-1. However, the COVID-19 pandemic and its associated lockdowns brought about an abrupt and persistent decline in TBMW disposal rates. Inconsistent fluctuations in both magnitude and variability of the monthly TBMW load weights were also observed. The TBMW load weight became particularly variable in 2020, with an interquartile range 4 times higher than 2019. The average TBMW load weight was also the lowest (5.1 tonnes∙month-1∙truckload-1) in 2020, possibly due to an overall decline in non-COVID-19 medical emergencies, cancellation of elective surgeries, and availability of telehealth options to residents. In general, the TBMW disposal rates peaked during the summer and fall seasons. The day-to-day TBMW disposal contribution patterns between the pre-pandemic and post-pandemic are similar, with 97.5% of total TBMW being disposed of on fixed days. Results from this Canadian case study indicate that there were observable temporal changes in TBMW disposal behaviors during and after the COVID-19 lockdowns.

Inhibition of the fungal fatty acid synthase type I multienzyme complex.

Fatty acids are among the major building blocks of living cells, making lipid biosynthesis a potent target for compounds with antibiotic or antineoplastic properties. We present the crystal structure of the 2.6-MDa Saccharomyces cerevisiae fatty acid synthase (FAS) multienzyme in complex with the antibiotic cerulenin, representing, to our knowledge, the first structure of an inhibited fatty acid megasynthase. Cerulenin attacks the FAS ketoacyl synthase (KS) domain, forming a covalent bond to the active site cysteine C1305. The inhibitor binding causes two significant conformational changes of the enzyme. First, phenylalanine F1646, shielding the active site, flips and allows access to the nucleophilic cysteine. Second, methionine M1251, placed in the center of the acyl-binding tunnel, rotates and unlocks the inner part of the fatty acid binding cavity. The importance of the rotational movement of the gatekeeping M1251 side chain is reflected by the cerulenin resistance and the changed product spectrum reported for S. cerevisiae strains mutated in the adjacent glycine G1250. Platensimycin and thiolactomycin are two other potent inhibitors of KSs. However, in contrast to cerulenin, they show selectivity toward the prokaryotic FAS system. Because the flipped F1646 characterizes the catalytic state accessible for platensimycin and thiolactomycin binding, we superimposed structures of inhibited bacterial enzymes onto the S. cerevisiae FAS model. Although almost all side chains involved in inhibitor binding are conserved in the FAS multienzyme, a different conformation of the loop K1413-K1423 of the KS domain might explain the observed low antifungal properties of platensimycin and thiolactomycin.