Matrix-assisted Laser Desorption/ionization Time-of-flight Research Articles

Penetration of Vegetable Oils into Textured Hair Fibers: Integrating Molecular Matrix Assisted Laser Desorption Ioni-Zation Time-of-Flight Mass Spectroscopy (MALDI TOF/TOF MS) Analysis with Mechanical Measurements

The promotion of natural beauty has empowered women with textured hair to embrace their natural hair texture and opt for bleaching as a means of style variation. However, bleaching exacerbates the inherent fragility of this hair type, necessitating treatments to partially restore its mechanical properties. Vegetable oils, renowned for their strengthening properties, were evaluated regarding (I) their ability to penetrate both virgin and bleached textured hair using Matrix-Assisted Laser Desorption Ionization (MALDI) time-of-flight (TOF) analysis, and (II) their effects by way of tensile and fatigue tests. The MALDI–TOF results revealed groups of oil molecules in the cortical region of the bleached textured hair. The tensile test results, in turn, showed that the oil treatments were unable to alter the mechanical properties of the hair. Conversely, the fatigue test showed an increase in resistance in the virgin hair, most likely attributed to a lubrication effect in the outermost portions of the cortex and cuticles. In the bleached hair, a reduction in resistance was noted following the treatment with the oils. Comparative analysis with a previous study on straight hair by our group suggests that external molecules diffuse more homogeneously in straight hair than in textured hair. The unique cortical structure of textured hair creates two areas with distinct diffusion zones, resulting in the irregular distribution of external materials and different effects compared to straight hair.

Tetracoordinate Boron(III) Compound with BF2O2 Skeleton as Monomer for the Synthesis of Tetracoordinate Oligoboranes

A new neutral tetracoordinate boron(III) compound 1 containing a BF2O2 skeleton was used as a monomer to produce a mixture of oligoboranes featuring sp3 B–B bonds via the Wurtz-type coupling reaction with metallic sodium in boiling toluene. 1, which is a difluoroboron compound that contains an O,O-donor ligand, showed intense greenish light emission in crystalline form with fluorescence quantum yield (ΦF) of 0.56 and aggregation-induced emission (AIE) phenomenon with ΦF of 0.25. The molecular structure of 1 was characterized by single-crystal X-ray diffraction and confirmed by 1H, 11B, 13C, 19F NMR and elemental analysis, while the mixture of oligomers was characterized by solution 1H, 11B, 13C, and 19F NMR and in the solid-state by 11B MAS NMR analysis. The Matrix-Assisted Laser Desorption/Ionization-Time-Of-Flight (MALDI-TOF) analysis confirmed that the oligoboranes are composed of a mixture of diborane and triborane species. Both in the solution and the solid state, 11B NMR analysis confirmed the boron atoms maintain the tetracoordination with sp3 hybridization. The Density Functional Theory (DFT) analysis was used to get more insights into the molecular structure of the diborane and triborane species.

Evaluation of a New Tandem Mass Spectrometry Method for Sickle Cell Disease Newborn Screening

In France, sickle cell disease newborn screening (SCD NBS) has been targeted to at-risk regions since 1984, but generalization to the whole population will be implemented from November 2024. Although tandem mass spectrometry (MS/MS) is already used for the NBS of several inherited metabolic diseases, its application for SCD NBS has not been widely adopted worldwide. The aim of this study was to evaluate a dedicated MS/MS kit (Targeted MS/MS Hemo, ZenTech, LaCAR Company, Liege, Belgium) for SCD NBS and to compare the results obtained with those from an NBS reference center using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) and cation-exchange high-performance liquid chromatography (CE-HPLC, Variant NBS, Biorad Laboratories, Inc., Hercules, CA, USA) as confirmatory method. The MS/MS Hemo kit was used according to the manufacturer’s instructions and performed on a Waters Xevo TQ-D (Waters Corporation, USA). The software provided by the manufacturer was used for the calculation and analysis of peptide signal ratios. Among the 1333 samples, the results of 1324 samples were consistent with the HPLC and/or MALDI-TOF results (1263 FA, 50 FAS, 7 FAC, 1 FAO-Arab, and 3 FS). All the discordant results (one FAS on MS/MS vs. FA in CE-HPLC, one FA on MS/MS vs. FAS in CE-HPLC, seven FS on MS/MS vs. FAS in CE-HPLC) were corrected after modifying the peptide signal ratios thresholds, allowing the MS/MS Hemo kit to achieve near-100% sensitivity and specificity for SCD NBS. In conclusion, the MS/MS Hemo kit appears to be an effective method for SCD NBS, particularly for laboratories already equipped with MS/MS technology. However, these results should be confirmed in a larger cohort including a greater number of positive samples for SCD.

“Clicking” Amphiphilic Block Copolymers onto POSS Core: A General Approach for “Star-like” Polymers with Different Symmetry

“Star-like” macromolecules have been widely studied because of their unique physical and chemical properties, which play a great role in many important application fields. In this study, a library of star-like amphiphilic block copolymers consisting of a polyhedral oligomeric silsesquioxane (POSS) core and polyethylene glycol-bolck-polystyrene (PEGm-b-PSn) diblock copolymer arms with an exact arm number were prepared through a robust copper-catalysed azide-alkyne cycloadditions (CuAAC) and strain-promoted azide-alkyne cycloaddition (SPAAC) click reactions. Moreover, homo- and mikto-arms star polymers with different compositions were obtained by precisely regulating the central symmetry of the POSS core. The target polymers and intermediate products were characterized by nuclear magnetic resonance (NMR), size exclusion chromatography (SEC), Fourier transform infrared (FT-IR) spectroscopy, and matrix-assisted laser desorption ionization time-of-flight (MALDI-ToF) mass spectrometry. This study demonstrates the chemical robustness of the novel POSS-based building block and establishes a general and efficient approach to prepare star-like macromolecules, especially for asymmetric heteroarm star-like macromolecules, which serve as important model compounds in the study of their bulk properties as well as self-assembling behaviors.

A novel LAMP-based assay for the identification of Streptococcus pneumoniae and Streptococcus pseudopneumoniae in clinical isolates.

The Gram-positive bacteria Streptococcus pneumoniae is part of the Streptococcus mitis group (SMG) and causes life-threatening infections, such as pneumonia, sepsis, and meningitis. The closely related Streptococcus pseudopneumoniae has recently been shown to cause respiratory tract infections, as well as invasive infections, especially in patients with comorbidities. Due to the genetic and phenotypic similarities of species belonging to the SMG, the identification of S. pneumoniae and S. pseudopneumoniae is difficult and unreliable using phenotypic tests, as well as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and 16S rRNA sequencing. In this study, a loop-mediated isothermal amplification (LAMP)-based assay was developed using molecular markers specific for S. pneumoniae (SPN0001) and S. pseudopneumoniae (SPPN_RS10375). The LAMP assay was evaluated using a collection of SMG clinical isolates, concluding that the method provides a correct, reliable, and fast identification of both S. pneumoniae and S. pseudopneumoniae clinical isolates.

Integration of MALDI glycotyping and NMR analysis to uncover an O-antigen substructure from pathogenic Escherichia coli O111

Escherichia coli O111 is a critical pathogenic E. coli serotype that causes severe, potentially fatal complications. Despite its reported variation, only one structure of the O-antigen polysaccharide from E. coli O111 has been reported. Here, a substructure of the O-antigen from E. coli O111 was characterized using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and NMR analysis. MALDI glycotyping revealed differing O-antigen repeating unit masses of Δm/z 787 and 828 in the E. coli strains and lipopolysaccharides from the O111 serogroup. This variation was caused by the replacement of the hexose residue with hexosamine in the repeating units, which was further confirmed by LIFT-TOF/TOF analysis. Structural elucidation of the O111 substructure by NMR analysis further demonstrated replacement of the hydroxyl group with an N-acetyl group on the terminal glucose residue of the O-antigen pentasaccharide repeating unit. To our knowledge, this study is the first to provide a detailed structural analysis of a new O-antigen substructure from the E. coli O111 serogroup.

Bacterial isolates and antibiotic sensitivity in canine bacterial keratitis in Korea.

To analyze bacterial isolates associated with canine bacterial keratitis and their antibiotic susceptibility patterns in Korea, focusing on multidrug resistance (MDR) and identifying effective antibiotic combinations for clinical treatment. A total of 146 dogs diagnosed with suspected bacterial keratitis between October 2022 and October 2023 in Korea, with 157 eye samples collected for analysis. Eye samples were cultured to isolate bacteria, and antibiotic susceptibility testing was performed using the minimum inhibitory concentration (MIC) method. Bacterial identification was conducted using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF). The study assessed the efficacy of individual antibiotics and combination therapies. Bacteria were isolated in 55.4% of the samples. The most common genera were Staphylococcus species (48.5%, 48/99), Streptococcus species (13.1%, 13/99), Pseudomonas species (9.1%, 9/99), and Escherichia coli (9.1%, 9/99). Amikacin (84.8%) showed the highest antibiotic susceptibility, while doxycycline exhibited the lowest (17.2%). The most effective antibiotic combinations were amikacin-moxifloxacin (93%). MDR isolates accounted for 52.5% (52/99) of the total bacterial samples. Staphylococcus species were the most common isolates, with 52.5% showing MDR, underscoring the need to curb antibiotic misuse. While antibiotics like amikacin demonstrated high susceptibility rates, their use should be reserved for resistant infections to prevent further resistance development. Rather than focusing solely on finding effective combinations of antibiotics, it is crucial to consider alternative treatment strategies that offer more sustainable solutions. Rather than relying on antibiotic combinations, attention should shift to sustainable alternatives to treat bacterial keratitis and reduce antibiotic dependence in clinical practice.

Serovars, virulence factors, and antimicrobial resistance profile of non-typhoidal Salmonella in the human-dairy interface in Northwest Ethiopia: A one health approach.

Non-typhoidal Salmonella (NTS) is a zoonotic pathogen that exerts huge public health and economic impacts in the world. The severity of illness is mainly related to the serovars involved, the presence of virulence genes, and antimicrobial resistance (AMR) patterns. However, data are scarce on serovars, virulence genes, and AMR among NTS identified from the human-dairy interface in Northwest Ethiopia. Thus, this study investigated the serovars, common virulence genes, and AMR patterns of NTS isolates in the area. The study was conducted from June 2022 to August 2023 among randomly selected 58 dairy farms. A total of 362 samples were processed to detect NTS using standard bacteriological methods. The presumptive positive colonies were confirmed by Matrix-Assisted Laser Desorption Ionization-Time-of-Flight (MALDi-ToF). Polymerase chain reaction (PCR) was used to detect virulence genes, including invA and spvC. A slide agglutination test according to the White-Kauffmann-Le Minor scheme was employed to identify the serovars of the NTS isolates. The Kirby-Bauer disk diffusion method was used to assess the antimicrobial susceptibility patterns. Of the processed samples (362), 28 (7.7%) NTS isolates were detected. When distributed among samples, the proportions were 11.9%, 10.5%, 10.3%, 5.2%, 4.3%, and 1.7% among cows' feces, dairy farm sewage, pooled raw milk, milk container swabs, milkers' stool, and milkers' hand swab samples, respectively. Six serovars were detected with the dominancy of S. Uganda (39.3%), followed by S. enterica subsp. diarizonae (25.0%) and S. Typhimurium (21.4%). Among the 28 NTS isolates, 100% and 21.4% had the virulence genes invA and spvC, respectively. The susceptibility profile showed that 89.3% of the NTS isolates were resistant to at least one antimicrobial agent and 46.4% were resistant to three or more classes of antimicrobials (multidrug-resistant). Among antimicrobials, isolates were highly resistant to ampicillin (57.1%), followed by tetracycline (42.9%) and chloramphenicol (35.7%). On the other hand, the NTS isolates were 100%, 96.4%, and 96.4% susceptible to ceftriaxone, azithromycin, and norfloxacin, respectively. In conclusion, we detected NTS from humans, dairy cows, raw milk, dairy utensils, and the environment (sewage), showing the potential of the human-dairy farm-environment nexus in the NTS circulation. These further highlight that the interface is a good point of intervention in the control and prevention of NTS infection. The susceptibility profiles of the isolate necessitate interventions including the prudent use of the antimicrobials.

Genomic characterization of Pantoea dispersa A003 isolated from a clinical patient

IntroductionPantoea dispersa is a Gram-negative bacterium generally considered as a plant pathogen and rarely causes human infections. To date, there have been 13 studies that have documented clinical infections linked to P. dispersa, with a primary emphasis on the initial identification of this pathogen. The genomic features and the mechanisms underlying the pathogenesis of P. dispersa remain largely uninvestigated. In the present study, we describe a clinical infection caused by P. dispersa and provide the first genomic analysis of this bacterium.MethodsThe bacterial strain designated A003 was isolated from blood samples. Preliminary identification of strain A003 was conducted using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) technology (VITEK® MS, bioMérieux, France). Biochemical and antimicrobial susceptibility assessments were carried out utilizing the VITEK-2 compact automated microbial analysis system (bioMérieux, France). Additionally, whole genome sequencing and subsequent analysis were performed to further elucidate the potential pathogenicity.ResultsThe bacterial isolate was cultured overnight at 35°C in a CO2-enriched environment on Columbia blood agar, resulting in the appearance of a white, smooth, Gram-negative rod-shaped bacterium with diameters ranging from 1 to 2 mm. Identification of strain A003 was achieved with a high confidence level of 99.9% as P. dispersa using MALDI-TOF mass spectrometry. The average nucleotide identity (ANI) value between strain A003 and the reference strain P. dispersa DSM 30073T was 98.08%, while the DNA–DNA hybridization (DDH) value was 84.10% (Formula 2) based on genome sequencing data, which further confirmed that A003 belonged to the P. dispersa species. Comprehensive analysis revealed the presence of 372 virulence factors, 15 antibiotic resistance genes, 222 carbohydrate-active enzymes, and 666 genes related to Type III secretion system (T3SS) effector proteins, as identified through the core databases of VFDB (Virulence Factors of Pathogenic Bacteria), CARD (Comprehensive Antibiotic Resistance Database), CAZY (Carbohydrate-Active enZYmes Database), and T3SS. The virulence factors included type IV pili (TFP), type VI secretion system, flagella, iron uptake system, and ompA, which are implicated in bacterial pathogenicity. The antibiotic resistance profile indicated resistance to fluoroquinolones, cephalosporins, penams, macrolides, and aminoglycosides, as annotated by the CARD database.ConclusionThe draft genome sequenced represents the inaugural genomic sequence of P. dispersa derived from clinical sources. This advancement may enhance clinical practitioners’ comprehension of the organism’s clinical attributes and serve as a foundational resource for future research into its virulence, antibiotic resistance, and host–pathogen interactions.

Whole genome sequencing (WGS) analysis of antimicrobial resistance (AMR) milk and dairy-derived pathogens from Anand, Gujarat, India

This study aimed to evaluate the antimicrobial resistance (AMR) patterns and genomic characteristics of Enterococcus faecalis, Enterococcus faecium, and Staphylococcus aureus strains isolated from dairy products, including buttermilk, curd, ice cream, and sweets, in the Anand region of Gujarat, India. A total of 205 isolates were analysed, with the highest contamination levels found in buttermilk and curd. The bacterial isolates were identified using biochemical tests and advanced Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) mass spectrometry. Antimicrobial susceptibility testing (AST) was performed using the Kirby-Bauer disk diffusion method, following CLSI guidelines, focusing on common antibiotics used for treating dairy-related bacterial infections. Resistance profiles were analysed using WHONET software.s The findings revealed significant multidrug resistance (MDR), particularly among E. faecium and E. faecalis, with over 95 % resistance to key antibiotics, including linezolid, ciprofloxacin, cefpodoxime, and carbapenems. Many strains were classified as MDR, XDR, and PDR. Staphylococcus aureus also exhibited substantial resistance to penicillin and enrofloxacin. whole-genome sequencing (WGS) and phylogenetic analysis to identify AMR determinants and conduct nucleotide sequence alignment. The study identified several antibiotic resistance genes, including LiaF, which regulates the expression of LiaR and LiaS genes. WGS revealed that genes such as GdpD, MprF, and PgsA encode intrinsic resistance determinants, contributing to antibiotic resistance. Additional AMR mechanisms were identified, including ABC transporter efflux pumps and the regulation of resistance genes by LiaR and LiaS. Phylogenetic analysis indicates a close relationship between Enterococcus faecium 640 1352.18624 and Enterococcus durans FB129-CNAB-4 883162.3.

A New Activity Assay Method for Diamine Oxidase Based on Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Copper-containing diamine oxidases are ubiquitous enzymes that participate in many important biological processes. These processes include the regulation of cell growth and division, programmed cell death, and responses to environmental stressors. Natural substrates include, for example, putrescine, spermidine, and histamine. Enzymatic activity is typically assayed using spectrophotometric, electrochemical, or fluorometric methods. The aim of this study was to develop a method for measuring activity using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry based on the intensity ratio of product to product-plus-substrate signals in the reaction mixtures. For this purpose, an enzyme purified to homogeneity from pea (Pisum sativum) seedlings was used. The method employed α-cyano-4-hydroxycinnamic acid as a matrix with the addition of cetrimonium bromide. Product signal intensities with pure compounds were evaluated in the presence of equal substrate amounts to determine intensity correction factors for data processing calculations. The kinetic parameters kcat and Km for the oxidative deamination of selected substrates were determined. These results were compared to parallel measurements using an established spectrophotometric method, which involved a coupled reaction of horseradish peroxidase and guaiacol, and were discussed in the context of data from the literature and the BRENDA database. It was found that the method provides accurate results that are well comparable with parallel spectrophotometry. This method offers advantages such as low sample consumption, rapid serial measurements, and potential applicability in assays where colored substances interfere with spectrophotometry.

Determination of nut varieties and their detection in festive cookies by MALDI-TOF mass spectrometry.

Nuts contain a large amount of essential fatty acids, amino acids, and whole range of minerals and vitamins valuable for human health, yet certain risks are associated with their consumption, of which allergic reaction is the most important. Considering the growing number of people suffering from allergies caused by allergens of protein origin, the aim of this work is to find out whether nuts can be distinguished from each other on the basis of contained proteins. A total of eleven raw and subsequently heat-treated nuts (almonds, Brazil nuts, cashews, coconuts, hazelnuts, macadamia nuts, peanuts, pecans, pine nuts, pistachios, and walnuts) were analyzed using MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry with the subsequent finding of characteristic m/z values for each analyzed nut. No previous method for protein extraction was used. The characteristic values were used to verify the composition of seven types of festive cookies - six commercial products and one "unknown" cookie, where it was not known in advance, which nut it was made from. The procedure, together with the found characteristic m/z values, could serve to rapidly identify the plant origin of nut products.

LncRNA LINC00261 associates with chemoresistance and clinical prognosis in patients with epithelial ovarian cancer.

The purpose of this experiment is to explore the role of long intergenic noncoding RNA 261 (LINC00261) gene in the chemoresistance and clinical prognosis of epithelial ovarian cancer (EOC). We used matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry to detect the methylation levels of the LINC00261 promoter region in EOC patient specimens. The expression levels of LINC00261, miR-545-3p, and MT1M in EOC patients were evaluated by quantitative real-time reverse transcriptase PCR (RT-qPCR). Spearman's correlation analysis was used for relevance analyses and clinical prognosis was counted by Kaplan-Meier analysis. Stable overexpressed LINC00261 SKOV3 cells were established to test the influence of LINC00261 on proliferation, platinum sensitivity, migration, and invasion. The promoter region methylation level of the LINC00261 was hypermethylated and LINC00261 was significantly downregulated in platinum-resistant EOC tissues. The methylation level of LINC00261was significantly negative correlated with its RNA expression in EOC. Moreover, hypermethylation and lower expression of LINC00261 in EOC patients were related to shorter progression-free survival (PFS) and overall survival (OS). Furthermore, Spearman's correlation analysis showed that the expression of miR-545-3p had a negative relevance with LINC00261. According to the website prediction, MT1M might be the downstream target gene of LINC00261. Expression of MT1M was negatively correlated with miR-545-3p and positively with LINC00261 in EOC tissues. And lower MT1M mRNA expression was correlated with chemotherapy resistance and worse prognosis. In vitro, overexpression of LINC00261 could inhibit cisplatin resistance, proliferation, and suppression of migration and invasion in SKOV3 cells. This research indicates that the aberrant hypermethylation and low expression of LINC00261 were associated with platinum resistance and adverse outcomes in EOC patients.

An investigation of scattered light integrating collector technology for rapid blood culture sensitivity testing.

Introduction. Sepsis rates are increasing, with Gram-negative organisms representing a large proportion of bloodstream infections. Rapid antibiotic administration, alongside diagnostic investigations, is required for the effective management of these patients.Gap statement. Current diagnostics take ~48 h for a final report; therefore, rapid diagnostics are required.Aim. This study investigated a novel antibiotic sensitivity method, the scattered light integrating collector (SLIC), combined with a rapid identification method using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) technology to determine if an accurate identification and susceptibility result can be provided within 4 h of a positive blood culture report.Methodology. A total of 47 blood cultures containing Gram-negative bacteria from 46 patients were processed using the MALDI-TOF Biotyper Sepsityper for identification directly from the blood and the SLIC instrument for susceptibility testing. All organisms were also tested using the current standard workflow used in the host laboratory. Categorical agreement (CA), major errors (MaEs) and very major errors (VMEs) were determined.Results. SLIC produced susceptibility results with a 71.9% CA, 30.6% MaE and 17.5% VME. The median difference in time to the final result was 44.14 (43 : 05-45 : 15) h earlier compared to the current method.Conclusion. We conclude that SLIC was unable to consistently provide sufficiently accurate antibiotic susceptibility results compared to the current standard method.

Isolation and characterization of <i>Salmonella enterica </i> associated with diarrhea in chickens and ducks in Hai Duong province

Salmonella infections, or salmonellosis, represent a significant threat to poultry health and the global poultry industry, leading to considerable economic losses and serving as a major source of foodborne illnesses in humans and animals. Identifying the specific strains present in local poultry farms is crucial for implementing targeted interventions, including the development of effective biosecurity measures, vaccination strategies, and treatment protocols to mitigate outbreaks. This study focuses on isolating and characterizing Salmonella strains associated with diarrhea in chickens and ducks in Hai Duong province, Vietnam. The Salmonella strains were initially isolated using a culture-based method, followed by identification and characterization through Matrix-Assisted Laser Desorption Ionization/Time of Flight (MALDI-TOF), PCR amplification of the invA gene, and 16S rRNA gene sequencing. As a result, 18 Salmonella isolates were obtained, all of which contained the invA gene, indicating its potential significance in Salmonella pathogenesis. Analysis of the 16S rRNA gene sequences confirmed that all isolates belonged to the species Salmonella enterica, a well-known causative agent of intestinal diseases in humans and animals. Furthermore, phylogenetic analysis revealed that all 18 isolates grouped with Salmonella enterica subsp. enterica strains from China and Korea, suggesting a close relationship with strains circulating in the broader Southeast Asian region. This regional similarity may be attributed to the movement of poultry and poultry products, facilitating the cross-border spread of Salmonella. Our findings underscore the importance of implementing robust biosafety measures throughout the poultry production chain to control the spread of Salmonella, thereby enhancing both animal and food safety.

Diagnostic performance of an automated robot for MALDI target preparation in microbial identification.

The MBT Pathfinder is an automated colony-picking robot designed for efficient sample preparation in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. This article presents results from three key experiments evaluating the instrument's performance in conjunction with MALDI Biotyper instrument. The method comparison experiment assessed its clinical performance, demonstrating comparable results with gram-positive, gram-negative, and anaerobic bacteria (scores larger than 2.00) and superior performance over simple direct yeast transfer (score: 1.80) when compared to samples prepared manually. The repeatability experiment confirmed consistent performance over multiple days and labs (average log score: 2.12, std. deviation: 0.59). The challenge panel experiment showcased its consistent and accurate performance across various samples and settings, yielding average scores between 1.76 and 2.19. These findings underline the MBT Pathfinder as a reliable and efficient tool for MALDI-TOF mass spectrometry sample preparation in clinical and research applications.

Design Optimization of a Novel Catalytic Approach for Transglucosylated Isomaltooligosaccharides into Dietary Polyols Structures by Leuconostoc mesenteroides Dextransucrase.

Polyols, or sugar alcohols, are widely used in the industry as sweeteners and food formulation ingredients, aiming to combat the incidence of diet-related Non-Communicable Diseases. Given the attractive use of Generally Regarded As Safe (GRAS) enzymes in both academia and industry, this study reports on an optimized process to achieve polyols transglucosylation using a dextransucrase enzyme derived from Leuconostoc mesenteroides. These enzyme modifications could lead to the creation of a new generation of glucosylated polyols with isomalto-oligosaccharides (IMOS) structures, potentially offering added functionalities such as prebiotic effects. These reactions were guided by a design of experiment framework, aimed at maximizing the yields of potential new sweeteners. Under the optimized conditions, dextransucrase first cleared the glycosidic bond of sucrose, releasing fructose with the formation of an enzyme-glucosyl covalent intermediate complex. Then, the acceptor substrate (i.e., polyols) is bound to the enzyme-glucosyl intermediate, resulting in the transfer of glucosyl unit to the tested polyols. Structural insights into the reaction products were obtained through nuclear maneic resonance (NMR) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analyses, which revealed the presence of linear α(1 → 6) glycosidic linkages attached to the polyols, yielding oligosaccharide structures containing from 4 to 10 glucose residues. These new polyols-based oligosaccharides hold promise as innovative prebiotic sweeteners, potentially offering valuable health benefits.

Biofilm mediated antibiotic resistant oral bacteria among Parkinson's patients

Aim: The aim of this study was to examine the oral microbe biofilm and antibiotic resistance in individuals with Parkinson's disease compared to those without the condition. Methodology: In this study, the oral bacteria of older patients with Parkinson's disease and those without the condition were examined for antibiotic resistance and biofilm formation. In this study, the microbiologists examined oral samples collected from 33 individual, out of which 18 sufferred from Parkinson's disease while the remaining 15 individuals were normal. This case involved the use of the Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) technology to identify six different species. Results: The analysis of oral samples showed the presence of six isolates viz. Staphylococcus epidermis, S. auricularis, S. simiae, Panebacillus thiaminolyticus, P. aeruginosa and Bacillus cereus. Out of these, P. thiaminolyticus was absent in the control group. The incidence of oral microorganisms was somewhat higher in Parkinson's disease patients than control individuals, however, there was no discernible variation in the oral bacterial strains found in the two research groups. The isolates underwent further analysis following Congo Red Agar and Tissue Culture Plate methods and showed positive result for biofilm formation. Each isolate found in the Parkinson's disease groups were found resistant to at least five antibiotics used. Interpretation: The ability to produce biofilm was present in approximately 83.3% of the isolates from the Parkinson's disease group and 80% of those from the control group. This study provides a deeper understanding of the relationship between biofilm-producing, antibiotic-resistant oral bacteria and Parkinson's disease, and also address the need for effective management of oral hygiene in Parkinson’s patients. Key words: Antibiotic resistance, Biofilm, Oral microbiota, Oral health, Parkinson’s disease

Label-free assessment of complement-dependent cytotoxicity of therapeutic antibodies via a whole-cell MALDI mass spectrometry bioassay

Potency assessment of monoclonal antibodies or corresponding biosimilars in cell-based assays is an essential prerequisite in biopharmaceutical research and development. However, cellular bioassays are still subject to limitations in sample throughput, speed, and often need costly reagents or labels as they are based on an indirect readout by luminescence or fluorescence. In contrast, whole-cell Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry (MS) has emerged as a direct, fast and label-free technology for functional drug screening being able to unravel the molecular complexity of cellular response to pharmaceutical reagents. However, this approach has not yet been used for cellular testing of biologicals. In this study, we have conceived, developed and benchmarked a label-free MALDI-MS based cell bioassay workflow for the functional assessment of complement-dependent cytotoxicity (CDC) of Rituximab antibody. By computational evaluation of response profiles followed by subsequent m/z feature annotation via fragmentation analysis and trapped ion mobility MS, we identified adenosine triphosphate and glutathione as readily MS-assessable metabolite markers for CDC and demonstrate that robust concentration–response characteristics can be obtained by MALDI-TOF MS. Statistical assay performance indicators suggest that whole-cell MALDI-TOF MS could complement the toolbox for functional cellular testing of biopharmaceuticals.

Urinary tract infection among people living with human immunodeficiency virus attending selected hospitals in Addis Ababa and Adama, central Ethiopia.

Urinary tract infections (UTIs) and antibacterial resistance (ABR) are important public health problems, but they are not well-studied among people living with human immunodeficiency virus (PLHIV) globally, especially in low-income countries. Therefore, it is important to regularly measure the extent of UTIs and ABR in the most susceptible populations. This study aimed to investigate the prevalence of UTIs, associated factors, bacterial causal agents, and their antibiotic susceptibility profile among PLHIV in central Ethiopia. A hospital-based cross-sectional study was conducted to recruit 688 PLHIV by a simple random sampling method. Background information was gathered through interviews, while clinical information was gathered from recent information sheets of patient charts using organized, pretested, and validated study tools. Midstream urine was collected aseptically and transported to the Microbiology Laboratory of Aklilu Lemma Institute of Pathobiology within 4 h of collection, maintaining its cold chain. Standard conventional microbial culture methods and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry were used to identify the bacterial isolates at the species level. Kirby Bauer's disk diffusion method was used to determine the antibiotic susceptibility profile of the bacterial isolates based on the interpretation guidelines of the Clinical Laboratory Standard Institute. Logistic regression models were used to examine factors associated with the occurrence of UTIs among PLHIV attending selected hospitals in Addis Ababa, and Adama. Out of 688 PLHIVs involved in the current study, 144 (20.9%) were positive for UTIs, whereas the majority were asymptomatic for UTIs. In the multivariable logistic regression analysis, only HIV RNA ≥ 200 copies/ml [AOR = 12.24 (95% CI, 3.24, 46.20), p < 0.01] and being symptomatic for UTIs during the study period [AOR = 11.57 (95% CI, 5.83, 22.97), p < 0.01] were associated with the occurrence of UTIs. The dominant bacterial species isolated were Escherichia coli (E. coli; n = 65; 43%), followed by Enterococcus faecalis (E. faecalis; n = 16; 10.6%) and Klebsiella pneumoniae (K. pneumoniae; n = 11; 7.3%). Over half of the E. coli isolates were resistant to antibiotics such as gentamicin (GM; n = 44; 67.7%), amikacin (AN; n = 46; 70.8%), nalidixic acid (NA; n = 42; 64.6%), ciprofloxacin (CIP; n = 40; 61.5%), and azithromycin (AZM; n = 45; 69.2%). All of the K. pneumoniae isolates (n = 11; 100%), (n = 6; 54.5%), and (n = 7; 63.6%) were resistant to [amoxicillin as well as amoxicillin + clavulanic acid], ceftriaxone, and sulfamethoxazole + trimethoprim, respectively. All the Staphylococcus aureus (S. aureus) isolates were resistant to cefoxitin, which implies methicillin-resistant S. aureus (MRSA). The high prevalence of UTIs and antibiotic resistance revealed in the current study needs public health interventions such as educating the population about preventive measures and the importance of early treatment of UTIs. Our findings also highlight the need to provide UTI screening services for PLHIV, and healthcare providers should adopt antibiotic stewardship programs to promote and ensure their appropriate and judicious use.