Tamaz Mdzinarashvili

Проведено калориметрическое и спектрофотометрическое исследование липосом с добавлением кальция и без него, полученных с помощью двух фосфолипидов (дипальмитоилфосфатидилхолин (DPPC) и 1-пальмитоил-2-линолеоил-фосфатид (DPPA)). Липосомы размером 200 нм были приготовлены по новой технологии. В качестве кальцийсодержащих молекул был использован CaCO3, который в медицине применяется как кальциевая добавка или как препарат от повышенной кислотности желудка. Липосомы были приготовлены в воде и в 20%-ном глицериновом растворе. Как калориметрические, так и спектрофотометрические эксперименты показали, что приготовленные по новой технологии кальцийсодержащие молекулы инкорпорируются в структурах липосом, что предоставляет возможность их использования в лечебных целях. Также необходимо отметить, что в таких липосомах кальций размещается в больших количествах и его попадание в кровоток не вызывает побочных эффектов. В работе была показана структура и термостабильность комплексных липосом. Полученные в ходе экспериментов кальцийсодержащие наночастицы могут быть как униламеллярными, так и мультиламеллярными. Их состояние зависит от типа фосфолипида и от среды, в которой липосомы получены. Липосомы, приготовленные в воде и в глицерине на основе DPPC фосфолипида, получились мультиламеллярными. Липосомы без добавки кальция, приготовленные основе DPPA фосфолипида в воде, получились униламеллярными, а с кальцием – мультиламеллярными. Липосомы, приготовленные на основе DPPA фосфолипида в глицерине, не зависимо от наличия в них кальция, получились мультиламеллярными. Кальцийсодержащие липосомы при успешном испытании на животных можно будет рекомендовать для людей, страдающих гиперкальциемией.

In the study, both uncomplexed and calcium-containing complex liposomes made of DPPA and DPPC phospholipids were studied calorimetrically and spectrophotometrical-ly. Liposomes with a diameter of 200 nm were produced by new nanotechnology. As cal-cium molecules, CaCO3 was used, which is used in medicine as a calcium supplement or antacid, which is used to relieve heartburn, stomach acidity. Complex liposomes were prepared in both water and 20 % glycerol solvent. As calorimetric and spectrophotometric experiments show, CaCO3 molecules made by new technology are incorporated into the structure of liposomes, which allows them to be used for treatment. In addition, calcium is placed in large quantities in such complex liposomes, although their entry into the blood does not cause side effects. The structure and thermal stability of complex liposomes were deter-mined in the paper. In particular, according to the obtained experimental results, we believe that the struc-ture of calcium-containing nanoparticles can be both unilaminar and multilaminar, in par-ticular, the structure of uncomplexed and calcium-containing DPPC liposomes prepared in water and glycerol are multilaminar. The structure of uncomplexed DPPA liposomes prepared in water is unilaminar, while calcium-containing DPPA liposomes prepared in water form a multilayer structure. As for the structure of both pure and calcium-containing DPPA liposomes prepared in glycerolare multilamellar. With some preliminary considera-tions, calcium-containing liposomes can be tested in experimental animals, and after obtaining positive results, they can be recommended for the treatment of hypocalcemia in humans.

A human organism depends on stable glucose blood levels in order to maintain its metabolic needs. Glucose is considered to be the most important energy source, and glycolysis is postulated as a backbone pathway. However, when the glucose supply is limited, ketone bodies and amino acids can be used to produce enough ATP. In contrast, for the functioning of the pentose phosphate pathway (PPP) glucose is essential and cannot be substituted by other metabolites. The PPP generates and maintains the levels of nicotinamide adenine dinucleotide phosphate (NADPH) needed for the reduction in oxidized glutathione and protein thiols, the synthesis of lipids and DNA as well as for xenobiotic detoxification, regulatory redox signaling and counteracting infections. The flux of glucose into a PPP—particularly under extreme oxidative and toxic challenges—is critical for survival, whereas the glycolytic pathway is primarily activated when glucose is abundant, and there is lack of NADP⁺ that is required for the activation of glucose-6 phosphate dehydrogenase. An important role of glycogen stores in resistance to oxidative challenges is discussed. Current evidences explain the disruptive metabolic effects and detrimental health consequences of chronic nutritional carbohydrate overload, and provide new insights into the positive metabolic effects of intermittent fasting, caloric restriction, exercise, and ketogenic diet through modulation of redox homeostasis.

There are many complicated pathogenic diseases caused by cell genes that are incorrectly expressed or not sufficiently active for normal cell functioning

The commercial solution of fourth generation (G4) of poly-amidoamine (PAMAM) dendrimers contains methanol, which is toxic for human body. Our differential scanning calorimetry (DSC) study of dendrimers confirmed the existence of this threat. The recommendation is done on how to prepare dendrimer solutions for practical and safely use in gene delivery. DSC have been also used to study the thermodynamic properties of DNA/dendrimer complexes (dendriplexes). We showed that up to DNA/dendrimer ratio 43 +/- 3 (w/w) the solution was homogeneous, but stable aggregates were formed at higher PAMAM content. DSC experiments performed with homogeneous solution of dendriplexes revealed existence of the pH-dependent melting curves that contain several endothermic peaks associated with melting of GC-rich regions.

According to the obtained experimental results, the thermal shock (from 37 to 53 °C) not only stops the multiplication process of Escherichia coli bacteria, but also causes bacterial titer to decrease gradually. After this period lasting up to 1 hour, the bacterial cells continue to grow. A similar type of response was observed when bacteria were subjected to acid shock. Increasing acidity of media leads to decrease of bacterial growth process, and finally, their titer curve sharply falls over time. Also, interesting results were obtained about necessary conditions for infecting the bacteria by phages. Particularly, DNA injection from phages into bacterial cells requires most of corresponding bacterial membrane receptors to be occupied by phages. We suppose that this occurs due to autocrine phenomenon when the signaling molecules block the DNA ejection from phage particles. This effect lasts until a certain number of phage particles are attached to the membrane. After that, DNA injection from phage head into the cytoplasm takes place and the process of bacterial infection begins. The real number of phages in a stock is by several orders higher than the number of plaque-forming units in a given stock, which is determined by a classical double-layer agar method.

Dipalmitoylphosphatidylcholine (DPPC) and 1,2-palmitoyl-phosphatidic acid (DPPA) liposomes, prepared by conventional rotary evaporation method, have similar structural organization, though they have significant differences. The similarity is that both types of lipids create standard bilayer liposomes with strong hydrophobic forces between lipids tails and with homogeneous bonds of hydrogen and electrostatic nature between hydrophilic lipids heads. By the calorimetric method, it has been shown that hydrophobic bonds break but liposomes’ destruction does not occur by heating till 150 °C. As for bonds between lipid heads in liposomes, their cooperative destruction takes place at 41 °C for DPPC and 66 °C for DPPA liposomes. In the case of thermal distraction of DPPC liposomes, two so-called pre transitions peaks were observed before the main transition peak, which indicates that DPPC liposomes’ structure is multilamellar. DPPA liposomes have one cooperative heat absorption peak, which points to a unilamellar structure of such liposomes. Substances of hydrophobic/hydrophilic nature, incorporated into the liposomes, are placed in hydrophobic or hydrophilic parts of liposomes, which lead to a change in calorimetric peak shapes and thermodynamic parameters. It has been shown that gold nanoparticles, incorporated into the DPPC liposomes, are able to enter Caco-2 cells. In contrast, these nanoparticles do not enter red blood cells.