Publications by authors named "Bernard Marasa"

In pharmaceutical manufacturing, ensuring product safety involves the detection and identification of microorganisms with human pathogenic potential, including Burkholderia cepacia complex (BCC), Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, Clostridium sporogenes, Candida albicans, and Mycoplasma spp., some of which may be missed or not identified by traditional culture-dependent methods. In this study, we employed a metagenomic approach to detect these taxa, avoiding the limitations of conventional cultivation methods.

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Pharmaceutical products contaminated with Burkholderia cepacia complex (BCC) strains constitute a serious health issue for susceptible individuals. New detection methods to distinguish DNA from viable cells are required to ensure pharmaceutical product quality and safety. In this study, we have assessed a droplet digital PCR (ddPCR) with a variant propidium monoazide (PMAxx) for selective detection of live/dead BCC cells in autoclaved nuclease-free water after 365 days, in 0.

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We report here the draft genome sequences of 16 fluoroquinolone-resistant extraintestinal Escherichia coli isolates from human patients. These isolates had high MICs (32 to 256 μg/mL) for ciprofloxacin and contained point mutations in the quinolone resistance-determining region (QRDR) of both and that confer resistance to fluoroquinolone. The whole-genome sequence data provide a better understanding of the fluoroquinolone resistance mechanisms in these isolates and would be beneficial in source tracking these pathogens during pandemic outbreaks.

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Simple and rapid detection of complex (BCC) bacteria, a common cause of pharmaceutical product recalls, is essential for consumer safety. In this study, we developed and evaluated a -based colorimetric loop-mediated isothermal amplification (LAMP) assay for the detection of BCC in (i) nuclease-free water after 361 days, (ii) 10 μg/mL chlorhexidine gluconate (CHX) solutions, and (iii) 50 μg/mL benzalkonium chloride (BZK) solutions after 184 days. The RibB 5 primer specifically detected 20 strains of BCC but not 36 non-BCC strains.

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In this study, we compared pulsed-field gel electrophoretic (PFGE), multilocus sequence typing (MLST), Staphylococcal cassette chromosome (SCC), typing, and virulence gene profiles of 19 Panton-Valentine leucocidin (PVL)-positive, multidrug-, and methicillin-resistant clinical (MRSA) isolates obtained from a hospital intensive care unit in Pakistan. The isolates exhibited 10 pulsotypes, contained eight adhesin genes ( and ), 10 toxin genes ( and ), and two other virulence genes () that were commonly present in all isolates. The -typing indicated seven known types (t030, t064, t138, t314, t987, t1509, and t5414) and three novel types.

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The presence of Burkholderia cepacia complex (BCC) strains has resulted in recalls of pharmaceutical products, since these opportunistic pathogens can cause serious infections. Rapid and sensitive diagnostic methods to detect BCC are crucial to determine contamination levels. We evaluated bacterial cultures, real-time PCR (qPCR), droplet digital PCR (ddPCR), and flow cytometry to detect BCC in nuclease-free water, in chlorhexidine gluconate (CHX) and benzalkonium chloride (BZK) solutions.

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The complex (BCC) is capable of remaining viable in low-nutrient environments and harsh conditions, posing a contamination risk in non-sterile pharmaceutical products as well as a challenge for detection. To develop optimal recovery methods to detect BCC, three oligotrophic media were evaluated and compared with nutrient media for the recovery of BCC from autoclaved distilled water or antiseptic solutions. Serial dilutions (10 to 10 CFU/ml) of 20 BCC strains were inoculated into autoclaved distilled water and stored at 6°C, 23°C and 42°C for 42 days.

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Chlorhexidine gluconate (CHX) and benzalkonium chloride (BZK) formulations are frequently used as antiseptics in healthcare and consumer products. Burkholderia cepacia complex (BCC) contamination of pharmaceutical products could be due to the use of contaminated water in the manufacturing process, over-diluted antiseptic solutions in the product, and the use of outdated products, which in turn reduces the antimicrobial activity of CHX and BZK. To establish a "safe use" period following opening containers of CHX and BZK, we measured the antimicrobial effects of CHX (2-10 μg/ml) and BZK (10-50 μg/ml) at sublethal concentrations on six strains of using chemical and microbiological assays.

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Aim: The goal of this study was to determine whether bacterial clearance in a rodent model would be impaired upon exposure to gold, silver or silica nanoparticles (NPs).

Materials & Methods: Mice received weekly injections of NPs followed by a challenge of Listeria monocytogenes (LM). On days 3 and 10 after LM injections, the animals were sacrificed and their tissues were collected for elemental analysis, electron microscopy and LM count determination.

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LMG 23361 is the type strain of the species isolated from the milk of a dairy sheep with mastitis. Some pharmaceutical products contain disinfectants such as benzalkonium chloride (BZK) and previously we reported that LMG 23361 possesses the ability to inactivate BZK with high biodegradation rates. Here, we report an improved high-quality draft genome sequence of this strain.

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Unlabelled: Pharmaceutical products that are contaminated with Burkholderia cepacia complex (BCC) bacteria may pose serious consequences to vulnerable patients. Benzyldimethylalkylammonium chloride (BZK) cationic surfactants are extensively used in medical applications and have been implicated in the coselection of antimicrobial resistance. The ability of BCC to degrade BZK, tetradecyldimethylbenzylammonium chloride (CBDMA-Cl), dodecyldimethylbenzylammonium chloride (CBDMA-Cl), decyldimethylbenzylammonium chloride (CBDMA-Cl), hexyldimethylbenzylammonium chloride, and benzyltrimethylammonium chloride was determined by incubation in 1/10-diluted tryptic soy broth (TSB) to determine if BCC bacteria have the ability to survive and inactivate these disinfectants.

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Here, we report the draft genome sequences of two methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates, hospital-associated perirectal isolate 32S (ST 239) from a colitis tracheostomy patient and community-associated MRSA isolate 42S (ST 772) from a hepatic-splenomegaly patient in Rawalpindi, Pakistan.

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In this paper, we present a draft genome sequence of a quality control reference strain, Enterococcus faecalis ATCC 51299 (multilocus sequencing type [MLST] ST6), which is sensitive to teicoplanin but resistant to vancomycin. It is used in an agar screening test for streptomycin, gentamicin, and vancomycin resistance and the resistance marker vanB.

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We report the draft genome sequence of a methicillin-resistant clinical Staphylococcus aureus isolate with a novel spa type and sequence type (ST291), isolated from a renal failure patient in Rawalpindi, Pakistan.

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Vancomycin-resistant Enterococcus faecium has emerged as a multidrug-resistant pathogen in hospital settings. Here, we present the draft genome sequence of a high-level vancomycin-resistant strain, E. faecium ATCC 51559, which is employed as a standard laboratory vanA genotype-positive control strain for clinical and laboratory studies.

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Multidrug-resistant Enterococcus faecium has emerged as a nosocomial pathogen that may infect the body at various sites, including the gastrointestinal tract, and has serious implications in human health and disease. Here, we present the draft genome sequence of clinical strain VRE3, which exhibited a sequence type 16 (ST16) pattern and carried truncated Tn1546, a mobile genetic element encoding a high level of vancomycin resistance.

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Here we report the whole draft genome sequence of a methicillin-resistant Staphylococcus aureus ST1413 strain. Determining the distribution and arrangement of various genes associated with drug resistance, toxicity, and diseases will enhance our understanding about its adaptability to thrive in different ecological niches and help in the development of effective treatments for enterotoxigenic staphylococcal infections.

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The bacteriophage T4 DNA packaging machine consists of a molecular motor assembled at the portal vertex of an icosahedral head. The ATP-powered motor packages the 56-µm-long, 170-kb viral genome into 120 nm × 86 nm head to near crystalline density. We engineered this machine to deliver genes and proteins into mammalian cells.

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Apoptosis plays a critical role in the maintenance of gut mucosal homeostasis and is highly regulated by numerous factors including polyamines. Decreasing cellular polyamines promotes the resistance of intestinal epithelial cells (IECs) to apoptosis by increasing Akt kinase activity, but the exact mechanisms by which polyamine depletion activates Akt remain unknown. 3-phosphoinositide-dependent protein kinase-1 (PDK1), functions as a downstream of phosphatidylinositol-3 kinase (PI3K) and upstream of Akt and serves as a major regulator of Akt activity.

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The cellular abundance of topoisomerase IIα (TOP2A) critically maintains DNA topology after replication and determines the efficacy of TOP2 inhibitors in chemotherapy. Here, we report that the RNA-binding protein HuR, commonly overexpressed in cancers, binds to the TOP2A 3'-untranslated region (3'UTR) and increases TOP2A translation. Reducing HuR levels triggered the recruitment of TOP2A transcripts to RNA-induced silencing complex (RISC) components and to cytoplasmic processing bodies.

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In mammalian cells, microRNAs regulate the expression of target mRNAs generally by reducing their stability and/or translation, and thereby control diverse cellular processes such as senescence. We recently reported the differential abundance of microRNAs in young (early-passage, proliferating) relative to senescent (late-passage, non-proliferating) WI-38 human diploid fibroblasts. Here we report that the levels of the vast majority of mRNAs were unaltered in senescent compared to young WI-38 cells, while overall mRNA translation was potently reduced in senescent cells.

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Adipose tissue development is tightly regulated by altering gene expression. MicroRNAs are strong posttranscriptional regulators of mammalian differentiation. We hypothesized that microRNAs might influence human adipogenesis by targeting specific adipogenic factors.

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MicroRNAs (miRNAs) are short non-coding RNAs that regulate diverse biological processes by controlling the pattern of expressed proteins. In mammalian cells, miRNAs partially complement their target sequences leading to mRNA degradation and/or decreased mRNA translation. Here, we have analyzed transcriptome-wide changes in miRNAs in senescent relative to early-passage WI-38 human diploid fibroblasts (HDFs).

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Neuronal development and plasticity are maintained by tightly regulated gene expression programs. Here, we report that the developmentally regulated microRNA miR-375 affects dendrite formation and maintenance. miR-375 overexpression in mouse hippocampus potently reduced dendrite density.

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Gene expression patterns vary dramatically in a tissue-specific and age-dependent manner. RNA-binding proteins that regulate mRNA turnover and/or translation (TTR-RBPs) critically affect the subsets of expressed proteins. However, very little is known regarding the tissue- and age-dependent expression of TTR-RBPs in humans.

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