The Global Spread of Microplastics: Contamination in Mussels, Clams, and Crustaceans from World Markets.

Analysis of microplastic (MP) occurrence in commercially relevant species is a prerequisite for food risk assessment. Using a standardized methodology, we aimed to investigate MP contamination in point-of-sale clams, mussels, and Crustacea shellfish collected from various markets (Belgium, Croatia, Serbia, and South Korea). An improved digestion protocol yielded ≥ 99.

Ovalbumin interaction with polystyrene and polyethylene terephthalate microplastics alters its structural properties.

Contaminating microplastics can interact with food proteins in the food matrix and during digestion. This study investigated adsorption of chicken egg protein ovalbumin to polystyrene (PS, 110 and 260 μm) and polyethylene terephthalate (PET, 140 μm) MPs in acidic and neutral conditions and alterations in ovalbumin structure. Ovalbumin adsorption affinity depended on MPs size (smaller > larger), type (PS > PET) and pH (pH 3 > pH 7).

Sandwich ELISA for the Quantification of Nucleocapsid Protein of SARS-CoV-2 Based on Polyclonal Antibodies from Two Different Species.

In this study, a cost-effective sandwich ELISA test, based on polyclonal antibodies, for routine quantification SARS-CoV-2 nucleocapsid (N) protein was developed. The recombinant N protein was produced and used for the production of mice and rabbit antisera. Polyclonal N protein-specific antibodies served as capture and detection antibodies.

The interplay between copper(II), human serum albumin, fatty acids, and carbonylating agent interferes with Cys 34 thiol reactivity and copper binding.

Cys34 thiol group of human serum albumin (HSA) represents major plasma antioxidant. Its reactivity is influenced by multiple factors. The influence of fatty acids (FA; saturated, mono, and poly unsaturated acids from fish oil) binding to HSA, on copper(II) binding affinity and Cys34 thiol group accessibility/reactivity, in the presence of carbonylation agent (methylglyoxal, MG) was examined.

Quantification of total content of non-esterified fatty acids bound to human serum albumin.

Non-esterified fatty acids bound to the human serum albumin (HSA) contribute to several HSAs properties of special concern in pathologies, for instance to the reactivity of the free HSA-Cys34 thiol group (important antioxidative thiol pool in plasma), and to the affinity for binding of molecules and ions (for example cobalt as a prominent biomarker in heart ischemia). Therefore, the method for determination of FAs bound to HSA was developed. FAs were released from HSA (previously isolated from serum by ammonium sulfate precipitation) using acidic copper(II) sulfate in phosphoric acid, extracted by n-heptane-chloroform (4:1, v/v) mixture, spotted on TL silica-gel and then developed with n-heptane-chloroform-acetic acid (5:3:0.

Binding of enterolactone and enterodiol to human serum albumin: increase of cysteine-34 thiol group reactivity.

The interaction of polyphenolic molecules with human serum albumin (HSA) could lead to changes in the reactivity of the HSA Cys34 thiol group (HSA-SH). The influences of enterolactone (EL) and enterodiol (ED) binding on HSA-SH reactivity in fatty acid (FA)-free HSA, and in HSA with bound stearic acid (S) in S/HSA molar ratios of 1:1 and 4:1, were investigated by the determination of the pseudo first order rate constants (k') for the thiol reaction with 5,5'-dithiobis-(2-nitrobenzoic acid). The binding affinities and binding sites of EL and ED were also determined, using fluorescence measurements of the intrinsic fluorescence of Trp214 and diazepam (binding site marker).

HSA carbonylation with methylglyoxal and the binding/release of copper(II) ions.

The potential of carbonylation with methylglyoxal to alter HSA's binding affinity for copper(II) ions and its influence on the release of copper(II) ions from copper-HSA complexes were studied. The affinity of HSA to coordinate copper(II) decreased upon carbonylation of the Cys34-SH group. Carbonylation of copper-HSA complexes caused a decrease in Cys34-SH content, conformational changes and the release of copper(II) ions.

Fatty acids binding to human serum albumin: Changes of reactivity and glycation level of Cysteine-34 free thiol group with methylglyoxal.

Fatty acids (FAs) binding to human serum albumin (HSA) could lead to the changes of Cys-34 thiol group accessibility and reactivity, i.e. its scavenger capacity and antioxidant property.

The efficiency of compounds with α-amino-β-mercapto-ethane group in protection of human serum albumin carbonylation and cross-linking with methylglyoxal.

α-Oxoaldehydes, which are produced in higher quantities in diabetes, uremia, oxidative stress, inflammation and aging, react with the amino, guanidine and thiol groups of proteins and cause the formation of advanced glycated end-products and protein cross-linking. To prevent these reactions, the efficiency of low molecular mass thiols with an α-amino-β-mercapto-ethane group (Cys, penicillamine and N-acetylcysteine (NAcCys, with a blocked amino group)) as scavengers of methylglyoxal, compared with glutathione (GSH) and the biguanidine derivative metformin, was investigated. The time courses of the reactions of the aforementioned compounds with methylglyoxal were assayed.

The influence of fatty acids on determination of human serum albumin thiol group.

During investigation of the changes of the Cys34 thiol group of human serum albumin (HSA) (isolated by affinity chromatography with Cibacron Blue (CB)) in diabetes, we found that the HSA-SH content was higher (11-33%) than the total serum thiol content. The influence of fatty acids (FA) binding to HSA on this discrepancy was investigated in vitro (using fluorescence and CD spectroscopy and GC) and with HSA samples from diabetic (n=20) and control groups (n=17). HSA-bound FA determine the selection of HSA molecules by CB and enhance reactivity and/or accessibility of the SH group.

Improving the reliability of human serum albumin-thiol group determination.

The thiol (Cys34) content of human serum albumin (HSA-SH) decreases during oxidative and carbonyl stress and, therefore, could represent a useful parameter in clinical practice. Nevertheless, the reliability of HSA-thiol determination with Ellman's method depends on the purity of isolated HSA. Determination of total serum thiols (mmol/L) and HSA-SH content (mmol -SH/mmol HSA) after HSA isolation from diabetic patient and control sera by a two-step precipitation with ammonium sulfate (AS), as well as HSA-SH contribution (%) to total serum thiols, was assessed.

Monitoring of the human serum albumin carbonylation level through determination of guanidino group content.

Carbonylation of the protein amino, guanidine, and thiol groups with α-oxoaldehydes (which are produced in higher quantities in diabetes, uremia, oxidative stress, aging, and inflammation) is one of the important causes of vascular complications. For monitoring of the human serum albumin (HSA) carbonylation level, a spectrophotometric method based on the formation of colored adduct between guanidine group and thymol-sodium hypobromite reagent in the alkaline medium was investigated. Beer's law is obeyed in the concentration range of Arg and protein guanidine groups from 1 to 40 mM.

Method for monitoring of the protein amino group changes during carbonylation.

Objectives: Carbonylation of the protein amino, guanidino and thiol groups is one of the important causes of vascular complications in diabetes. We developed a simple spectrophotometric method for monitoring of the changes in the protein amino group contents during carbonylation.

Design And Methods: The method is based on the reaction of amino group with p-benzoquinone in the slightly alkaline media.

Influence of the microenvironment of thiol groups in low molecular mass thiols and serum albumin on the reaction with methylglyoxal.

Methylglyoxal (MG), a reactive alpha-oxoaldehyde that is produced in higher quantities in diabetes, uremia, oxidative stress, aging and inflammation, reacts with the thiol groups (in addition to the amino and guanidino groups) of proteins. This causes protein modification, formation of advanced glycated end products (AGEs) and cross-linking. Low molecular mass thiols can be used as competitive targets for MG, preventing the reactions mentioned above.

Influence of pigments and pH of urine on the determination of N-acetyl-beta-D-glucosaminidase activity with 2-methoxy-4-(2'-nitrovinyl)-phenyl-N-acetyl-beta-D-glucosaminide.

The influence of urinary pigments and urine pH on the spectrophotometric determination of N-acetyl-beta-D-glucosaminidase (NAG; EC 3.2.1.

The possibility of determining N-acetyl-beta-D-glucosaminidase isoenzymes under alkaline conditions.

Objectives: To have a reliable diagnostic test, the influence of urine pH on the determination of the total activity of N-acetyl-beta-D-glucosaminidase (NAG) and NAG isoenzyme activities was studied.

Design And Methods: After ultrafiltration and dialysis of the acidic and alkaline urines, the B, A, and A2 forms of NAG were separated by ion-exchange chromatography on DEAE cellulose.

Results: A significant decrease in the total activity of NAG in alkaline urines (pH around 8 or higher) was found, which makes this determination unreliable.

Change in the iso-enzyme profiles of urinary N-acetyl-beta-D-glucosoaminidase in workers exposed to mercury.

The iso-enzyme profiles of urinary N-acetyl-beta-D-glucosoaminidase (NAG) were studied in the workers from a chloro-alkaline electrolysis plant that had been continuously exposed to elemental mercury. The same workers then had a work break of four months and were later re-exposed to mercury for another five months. The activities of urinary NAG in workers exposed to mercury before and after the work break and in the control group were 2.

Reactivity of IGF binding protein-3 isoforms towards concanavalin A in healthy adults and subjects with cirrhosis.

The capacity of the liver to synthesize insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) may be compromised by alcohol. The characteristics of IGFBP-3 variants obtained from healthy individuals and patients with alcoholic cirrhosis (ALC) were compared. Concanavalin A (Con A) affinity electrophoresis and ligand blotting demonstrated that there was a gradual change in carbohydrate properties of putative IGFBP-3 with progression of ALC from stages A to C.