Human serum albumin (HSA) is a protein that transports neutral and acid ligands in the organism. Depending on the environment’s pH conditions, HSA can take one of the five isomeric forms that change its conformation. HSA can form aggregates resembling those in vitro formed from amyloid at physiological pH (neutral and acidic). Not surprisingly, the main goal of the research was aggregation/fibrillation of HSA, the study of the physicochemical properties of formed amyloid fibrils using thioflavin T (ThT) and the analysis of ligand binding to aggregated/fibrillated albumin in the presence of dansyl-l-glutamine (dGlu), dansyl-l-proline (dPro), phenylbutazone (Phb) and ketoprofen (Ket). Solutions of human serum albumin, both non-modified and modified, were examined with the use of fluorescence, absorption and circular dichroism (CD) spectroscopy. The experiments conducted allowed observation of changes in the structure of incubated HSA (HSA_INC) in relation to nonmodified HSA (HSA_FR). The formed aggregates/fibrillation differed in structure from HSA monomers and dimers. Based on CD spectroscopy, previously absent β-structural constructs have been registered. Whereas, using fluorescence spectroscopy, the association constants differing for fresh and incubated HSA solutions in the presence of dansyl-amino acids and markers for binding sites were calculated and allowed observation of the conformational changes in HSA molecule.

Albumin is one of the most important proteins in human blood. Among its multiple functions, drug binding is crucial in terms of drug distribution in human body. This protein undergoes many modifications that are certain to influence protein activity and affect its structure. One such reaction is albumin oxidation. Chloramine T is a strong oxidant. Solutions of human serum albumin, both non-modified and modified by chloramine T, were examined with the use of fluorescence, absorption and circular dichroism (CD) spectroscopy. 10H-3,6-diazaphenothiazine (DAPT) has anticancer activity and it has been studied for the first time in terms of binding with human serum albumin—its potential as a transporting protein. Using fluorescence spectroscopy, in the presence of dansylated amino acids, dansyl-l-glutamine (dGlu), dansyl-l-proline (dPro), DAPT binding with two main albumin sites—in subdomain IIA and IIIA—has been evaluated. Based on the conducted data, in order to measure the stability of DAPT complexes with human (HSA) and oxidized (oHSA) serum albumin, association constant (K_a) for ligand-HSA and ligand-oHSA complexes were calculated. It has been presumed that oxidation is not an important issue in terms of 10H-3,6-diazaphenothiazine binding to albumin. It means that the distribution of this substance is similar regardless of changes in albumin structure caused by oxidation, natural occurring in the organism.

Background: The aim of the present study was to evaluate the effects of post-activation performance enhancement (PAPE) during successive sets of the bench press (BP) exercise under blood flow restriction (BFR). Methods: The study included 10 strength-trained males (age = 29.8 ± 4.6 years; body mass = 94.3 ± 3.6 kg; BP 1-repetition maximum (1RM) = 168.5 ± 26.4 kg). The experiment was performed following a randomized crossover design, where each participant performed two different exercise protocols: under blood flow restriction (BFR) and control test protocol (CONT) without blood flow restriction. During the experimental sessions, the study participants performed 3 sets of 3 repetitions of the BP exercise at 70%1RM with a 5 min rest interval between sets. The differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) between the CONT and BFR conditions were examined using 2-way (condition × set) repeated measures ANOVA. Furthermore, t-test comparisons between conditions were made for the set 2–set 1, set 3–set 1, and set 3–set 2 delta values for all variables. Results: The post hoc results for condition × set interaction in PP showed a significant increase in set 2 compared to set 1 for BFR (p < 0.01) and CONT (p = 0.01) conditions, a significant increase in set 3 compared to set 1 for the CONT (p = 0.01) condition, as well as a significant decrease in set 3 compared to set 1 for BFR condition occurred (p < 0.01). The post hoc results for condition × set interaction in PV showed a significant increase in set 2 compared to set 1 for BFR (p < 0.01) and CONT (p = 0.01) conditions, a significant increase in set 3 compared to set 1 for CONT (p = 0.03) condition, as well as a significant decrease in set 3 compared to set 1 for BFR condition (p < 0.01). The t-test comparisons showed significant differences in PP (p < 0.01) and PV (p = 0.01) for set 3–set 2 delta values between BFR and CONT conditions. Conclusion: The PAPE effect was analyzed through changes in power output and bar velocity that occurred under both the CONT and BFR conditions. However, the effects of PAPE have different kinetics in successive sets for BFR and for CONT conditions.

The interaction of drugs with human serum albumin (HSA) is an important element of therapy. Albumin affects the distribution of the drug substance in the body, as well as its pharmacokinetic and pharmacodynamic properties. On the one hand, inflammation and protein glycation, directly associated with many pathological conditions and old age, can cause structural and functional modification of HSA, causing binding disorders. On the other hand, the widespread availability of various dietary supplements that affect the content of fatty acids in the body means that knowledge of the binding activity of transporting proteins, especially in people with chronic diseases, e.g., diabetes, will achieve satisfactory results of the selected therapy. Therefore, the aim of the present study was to evaluate the effect of a mixture of fatty acids (FA) with different saturated and unsaturated acids on the affinity of acetohexamide (AH), a drug with hypoglycaemic activity for glycated albumin, simulating the state of diabetes in the body. Based on fluorescence studies, we can conclude that the presence of both saturated and unsaturated FA disturbs the binding of AH to glycated albumin. Acetohexamide binds more strongly to defatted albumin than to albumin in the presence of fatty acids. The competitive binding of AH and FA to albumin may influence the concentration of free drug fraction and thus its therapeutic effect.