Dendrimers provide many exciting opportunities for potential biomedical applications. However, owing to their positively charged surfaces, poly(propyleneimine) (PPI) dendrimers show toxic and haemolytic activities. One of the methods for masking the peripheral cationic groups is to modify them using carbohydrate residues. In this study, three types of the fourth generation PPI dendrimers-uncoated (PPI-g4), approximately 35% maltotriose (Mal-III)-coated (PPI-g4-OS), and approximately 90% Mal-III-coated (PPI-g4-DS) were investigated by assessing their effects on red blood cell (RBC) haemolysis in samples of pure RBCs, RBCs in the presence of human serum albumin (HSA) or human plasma, and RBCs in whole blood. Lymphocyte proliferation and platelet (PLT) aggregation were also studied in the presence of various concentrations of dendrimers. Although all dendrimers examined affected all the blood cells studied, the unmodified PPI-g4 had the most damaging effect. It caused high RBC haemolysis rates and PLT aggregation and greatly inhibited lymphocyte proliferation. These effects were caused by the cationic surface of this polymer. The modification of PPI-g4 with Mal-III reduced the effect of the dendrimer on all blood cells. The presence of HSA or plasma in the buffer containing the RBCs or RBC in whole blood significantly decreased the extent of dendrimer-driven haemolysis.

Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by the aggregation of extracellular b-amyloid and the intracellular microtubule-associated protein Tau. Neurodegeneration is associated inter alia with the activation of microglial cells, neuroinflammation, oxidative stress, and diminished transduction of impulses in cholinergic neurons. Current pharmacotherapy for AD is based mainly on modulation of acetylcholine hydrolysis, administration of non-steroidal anti-inflammatory drugs and antioxidants. Novel drugs with antiamyloidic properties are currently being sought. Cationic phosphorus dendrimers have been proven to modulate amyloidogenesis and stop the aggregation of Tau protein. An ideal drug for AD should demonstrate anti-inflammatory properties, inhibit acetylcholine hydrolysis, and have antioxidant capacity. Cationic phosphorus dendrimers (generation 3 and generation 4) show the foregoing properties. They inhibit acetylcholinesterase activity, can decrease the secretion of TNF-a, and have weak antioxidant effects. The results presented suggest that phosphorus dendrimers may be considered in the future as agents in AD therapy.

The biostimulating activity of low level laser radiation of various wavelengths and energy doses is widely documented in the literature, but the mechanisms of the intracellular reactions involved are not precisely known. The aim of this paper is to evaluate the influence of low level laser radiation from an multiwave locked system (MLS) of two wavelengths (wavelength = 808 nm in continuous emission and 905 nm in pulsed emission) on the human erythrocyte membrane and on the secondary structure of human serum albumin (HSA). Human erythrocytes membranes and HSA were irradiated with laser light of low intensity with surface energy density ranging from 0.46 to 4.9 J cm−2 and surface energy power density 195 mW cm−2 (1,000 Hz) and 230 mW cm−2 (2,000 Hz). Structural and functional changes in the erythrocyte membrane were characterized by its fluidity, while changes in the protein were monitored by its secondary structure. Dose-dependent changes in erythrocyte membrane fluidity were induced by near-infrared laser radiation. Slight changes in the secondary structure of HSA were also noted. MLS laser radiation influences the structure and function of the human erythrocyte membrane resulting in a change in fluidity.

Introduction. Authors of numerous publications have proved the therapeutic effect of laser irradiation on biological material, but the mechanisms at cellular and subcellular level are not yet well understood. Objective. The aim of this study was to assess the effect of laser radiation emitted by the MLS M1 system (Multiwave Locked System) at two wavelengths (808 nm continuous and 905 nm pulsed) on the stability and fluidity of liposomes with a lipid composition similar to that of human erythrocyte membrane or made of phosphatidylocholine. Materials and method. Liposomes were exposed to low-energy laser radiation at surface densities 195 mW/cm 2 (frequency 1,000 Hz) and 230 mW/cm 2 (frequency 2,000 Hz). Different doses of radiation energy in the range 0-15 J were applied. The surface energy density was within the range 0.46 -4.9 J/cm 2 . Results. The fluidity and stability of liposomes subjected to such irradiation changed depending on the parameters of radiation used. Conclusions. Since MLS M1 laser radiation, depending on the parameters used, affects fluidity and stability of liposomes with the lipid content similar to erythrocyte membrane, it may also cause structural and functional changes in cell membranes.

No abstract