Research Publications (Food Safety)

The use of antimicrobial agents in livestock breeding is inevitable for prophylactic and treatment purposes, in order to maintain health and improve production of food products. However, this practice resulted in development of community resistance to antimicrobials due to residues found in livestock products. Milk is a key nutritional product that’s widely consumed for its high nutritional value.

Predictions of drug residues in milk are critical in food protection and are a major consideration in the economics of treatment of mastitis in dairy cows. Nonlinear mixed-effects modeling (NLME) has been advocated as a suitable pharmaco-statistical method for the study of drug residues in milk. Recent developments in physiologically based pharmacokinetic (PBPK) modeling of intramammary drugs allow the combination of a mechanistic description of milk pharmacokinetics with NLME methods.

BACKGROUND The contamination of milk by antibiotic residues represents risks to the health of the consumers, therefore they should be monitored.

by Malathi Banda, Karen L. McKim, Meagan B. Myers, Masahiro Inoue, Barbara L. Parsons

Sulfane sulfur such as glutathione persulfide (GSSH) is produced from H2S oxidation or from L‐cysteine metabolism. It accumulates inside Pseudomonas aeruginosa PAO1 during the stationary phase of growth, inactivating a repressor to increase the expression of a major multidrug efflux pump. The finding explains why the bacterium is relatively resistant to antibiotics at the stationary phase of growth.

In this study, mAb-5A7 and mAb-1D7, two highly specific monoclonal antibodies against tylosin (TYL), were prepared by using hapten TYL-carboxymethoxylamine hemihydrochloride (TYL-CMO), and they showed IC50 values of 13.84 ng/mL and 13.01 ng/mL and LODs of 1.21 and 0.98 ng/mL, respectively, in indirect competitive enzyme-linked immunosorbent assay.

In the present investigation, the parent compound 4-amino-5-(4-fluoro-3-phenoxyphenyl)-4H-1,2,4-triazole-3-thiol (1) and its Schiff bases 2, 3, and 4 were subjected to whole-cell anti-TB against H37Rv and multi-drug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) by resazurin microtiter assay (REMA) plate method. Test compound 1 exhibited promising anti-TB activity against H37Rv and MDR strains of MTB at 5.5 µg/mL and 11 µg/mL, respectively.

The vast majority of medicines in pig rearing are administered via oral group medication through medicated feed and drinking water. However, relevant on-farm factors affecting the concentration of these drugs in feed and drinking water, such as the homogeneity, stability, and cross-contamination, are largely unknown.

The residual characteristics and risk assessment with respect to cyazofamid and its metabolite 4-chloro-5-p-tolylimidazole-2-carbonitrile were monitored in case of Korean cabbage at different preharvest intervals during a greenhouse trial. The 0.02 kg a.i/ha of cyazofamid was sprayed twice on seven-day intervals (i.e., on day 0, 7, 14, and 21 before harvest). The liquid chromatography–tandem mass spectrometry analysis was used to monitor the residual amount of fungicide.

Drug-resistant bacteria infections and drug residues have been increasing and causing antibiotic resistance and public health threats worldwide. Antimicrobial peptides (AMPs) are novel antimicrobial drugs with the potential to solve these problems. Here, a peptide based on our previously studied peptide PMAP-36PW was designed via N-terminal myristoylation and referred to as Myr-36PW.

Author(s): Quoc Tuc Dinh, Gabriel Munoz, Sung Vo Duy, Dat Tien Do, Stéphane Bayen, Sébastien Sauvé

Author(s): Qin Wu, Qiang Zhu, Muhammad Abu Bakr Shabbir, Adeel Sattar, Dapeng Peng, Yanfei Tao, Dongmei Chen, Zonghui Yuan, Yulian Wang

ABSTRACT

Erm proteins methylate a specific adenine residue (A2058, Escherichia coli coordinates) conferring macrolide-lincosamide-streptogramin B (MLSB) antibiotic resistance on a variety of microorganisms, ranging from antibiotic producers to pathogens.

Antibiotic abuse in agricultural products leads to serious food safety issues. To this end, we proposed a mix-and-read and enzyme-free amplified assay for antibiotics based on a dual triple helix-aptamer probe, potentially applicable for on-site monitoring of antibiotic residues. A dual triple helix-aptamer probe can leverage the response toward target molecules without enzyme-based amplification, rendering it sensitive and robust for profiling target molecules.

Multi-drug resistance (MDR) is a serious threat to public health, making the development of new antimicrobials an urgent necessity. Pyocins are protein antibiotics produced by Pseudomonas aeruginosa strains to kill closely related cells during intraspecific competition. Here, we report an in depth biochemical, microbicidal and structural characterization of a new S-type pyocin, named S8. Initially, we described the domain organization and secondary structure of S8.

The problems of parasite resistance, as well as the toxic residues to most of the commercially available antipiroplasmic drugs severely weaken their effective, curative, and environmental safe employment. Therefore, it is clear that the development of treatment options for piroplasmosis is vital for improving disease treatment and control. Ciprofloxacin is a broad-spectrum antibiotic that targets mainly the DNA replication machinery by inhibiting DNA gyrase and topoisomerase enzymes.

About 19 hydrolyzable tannins were computed against 3CLpro enzyme of 2019‐nCoV. It was found that pedunculagin, tercatain, and castalin interacted with Cys145 and His41 of 2019‐nCoV‐3CLpro. Likewise, pedunculagin‐2019‐nCoV‐3CLpro remain stable, with no obvious fluctuations. We predicted that the understandings obtained in the current study may evidence valued for discovering and unindustrialized novel natural anti‐COVID‐19 therapeutic agents in the near future.

American foulbrood is one of the most serious and yet unsolved problems of beekeeping around the world, because it causes a disease leading to the weakening of the vitality of honey bee populations and huge economic losses both in agriculture and horticulture. The etiological agent of this dangerous disease is an extremely pathogenic spore-forming bacterium, Paenibacillus larvae, which makes treatment very difficult.

The antibiotic residues were investigated in raw and pasteurized milk produced in Neyshabur region, Iran. To this end, 82 milk samples, including raw and pasteurized milk of different brands and local raw milk samples of collection centers, were collected from Neyshabur region in two seasons during 2016. The antibiotic four-plate test (FPT) was performed to examine the presence of tetracycline, flomocaine, sulfonamide, enrofloxacin, aminoglycoside, and macrolide in the samples.

Antimicrobial peptides (AMPs) are promising candidates for new therapeutics to combat the emergence of an increasing number of multidrug-resistant pathogens. However, a major obstacle to the systemic application of AMPs is their possible toxicity. In this study, we improved the therapeutic index of the typical AMP F5W-magainin 2 by simultaneously introducing positive charges (+9–+10) and Pro residues.

Several analgesic α-conotoxins have been isolated from marine cone snails. Structural modification of native peptides has provided potent and selective analogues for two of its known biological targets—nicotinic acetylcholine and γ-aminobutyric acid (GABA) G protein-coupled (GABAB) receptors. Both of these molecular targets are implicated in pain pathways.

Visceral leishmaniasis (VL, also known as kala-azar) is a vector borne disease caused by obligate intracellular protozoan parasite Leishmania donovani. To overcome the limitations of currently available drugs for VL, molecular target-based study is a promising tool to develop new drugs to treat this neglected tropical disease. One such target we recently identified from L.

Peptide sequencing is critical to the quality control of peptide drugs and functional studies of active peptides. A combination of peptidase digestion and mass spectrometry technology is common for peptide sequencing. However, such methods often cannot obtain the complete sequence of a peptide due to insufficient amino acid sequence information. Here, we developed a method of generating full peptide ladders and comparing their MS2 spectral similarities.

Cholesterol is a major carbon source for Mycobacterium tuberculosis (Mtb) during infection, and cholesterol utilization plays a significant role in persistence and virulence within host macrophages. Elucidating the mechanism by which cholesterol is degraded may permit the identification of new therapeutic targets. Here, we characterized EchA19 (Rv3516), an enoyl-CoA hydratase involved in cholesterol side-chain catabolism.