Postepy Biologii Komorki, vol. 32, 2005, issue 1

Summary: The problem of molecules interaction based on the spatial structure is central to many fields of biology. Methods of building libraries that contain vast numbers of different molecules offer new approach in ligand-oriented research. One of these methods is phage display technology using libraries of peptides displayed on filamentous phage particles. Among many applications of the technique, structural peptide mimicry seems to be particularly important, since it opens a possibility for cancer immunotherapy to utilise peptide epitopes instead of glycolipid ones. The search for peptide sequences that mimic GD2 ganglioside present on neuroblastoma cancer cells comes as an example of this strategy.

Key words: peptide libraries, phage display, mimeotopes, cancer immunotherapy

Summary: The possibility to induce tolerance to brain ischemia by different stimuli draws attention of many researchers. The perspective to make the brain, even transiently, more resistant to reduced blood flow seems to be very attractive considering its potentially clinical application. Molecular mechanisms of preconditioning are known only fragmentary, so far. The present work summarizes the current knowledge about factors involved in the induction of brain ischemic tolerance.

Summary: An effective iron uptake by parasitic protozoa is a determining factor for their survival in host. The available iron source, for which the parasite must compete with the macroorganism, depends on the niche where it resides and its life mode (intracellular or/and extracellular). In the paper an iron acquisition from chelate compounds (transferrin, lactoferrin) in selected protozoan species has been presented. A particular interest has been focused on flagellated protozoon, Trypanosoma brucei. In concluding remarks any particular problems associated with the studies on iron metabolism in intracellular parasitic protozoa and a significant variety of protozoan receptors involved in iron delivery, depending on a parasite species and form, have been pointed out.

Summary: Plant genes encoding metabolism of trehalose were discovered not so long ago. There are more and more of dates indicating on regulatory function of trehalose and trehalase in sugar sensing and signaling as well as in the control of assimilate allocation. Nevertheless the function of trehalose metabolism in plants is still not clear.

Summary: Now, it is known that aberrant cell adhesion is one of the main mechanism involved in tumor progression. Formation of metastases in majority of thyroid carcinomas evidenced the disturbance in this process. In this review, the proteins playing role in regulation of cell adhesion in thyroid neoplasms are described.

Key words: thyroid tumors, cadherins, catenins, integrins, glycoprotein CD44, dysadherin

Summary: Achieving immunological tolerance is an important goal in the effort to reduce long-term morbidity and mortality in organ transplant recipients. The establishment of mixed chimerism through the transplantation of donor bone marrow cells is an experimental approach for tolerance induction with clinical potential. Permanent, robust donor-specific tolerance has been reliably achieved in various animals models of mixed chimerism. This article reviews the historical background and the progress achieved in recent years in developing mixed chimerism protocols in rodents, large animals and also regards the issue of clinical applications.

Key words: allograft, haematopoietic stem cells, mixed chimerism, immunological tolerance, organ transplantation

Quorum Sensing – Bacterial Cell - to - Cell Communication Using Chemical Signal Molecules

Summary: Due to the great genetic and physiological variability bacteria are able to colonize different ecological niches and rapidly adapt to the changing environmental conditions. Bacterial quorum sensing system (QS) represents one of the important mechanisms allowing bacterial cells to regulate physiological activities on the global, highly synchronized level. This system is defined as a method of intra- and interspecies communication of bacterial cells. Significant advances in the analyses of quorum sensing components show that most if not all bacterial species have developed specialized pathways for synthesis of diffusible signal molecules and receptor proteins serving as specific receptors for such signals, as well as systems for transmission of the signals onto efector proteins and, ultimately, target genes. Global regulation using QS system regulates many basic activities of bacteria such: symbiosis, virulence, competence, conjugation, antibiotics production, sporulation, biofilms formation, swarming. In Gram-negative bacteria, acyl homoserine lactones act as signal molecules, whereas in Gram-positive bacteria this role is played by oligopeptides. There are hypotheses that QS system in presently living bacteria represents early stages of multicellular organisms evolution.

Ghrelin – Regulation of Feeding, Growth Hormone Release and Other Actions of a New Hormone

Summary: Ghrelin, an acetylated peptide composed of 28 amino-acids, is an endogenous ligand for the growth hormone secretagogues receptor, GHS-R. Ghrelin is mainly produced by the X/A cells of the oxyntic glands in the stomach and, to a much lesser extent, in hypothalamus, pituitary, adrenal gland, intestine, gonads, heart, T lymphocytes, and monocytes. Ghrelin increases growth hormone secretion independently on and synergistically with somatoliberin. It is the only peripheral hormone that increases appetite and food intake by stimulating hypothalamic neurons that secrete key orexinogens, neuropeptide Y and AgRP, and by inhibiting anorexigenic ?-MSH neurons. Serum level of ghrelin increases during fasting and becomes suppressed by refeeding and in obesity. Ghrelin increases secretory activity and motility of stomach and ileum, induces proliferation of some cell lines and shows gastro- and cardioprotective properties.

Minimal Residual Disease Assessment in Multiple Myeloma Patients. Part I. Flow Cythometry Method

Summary: Introducing of the new methods of treatment of MM patients is connected with necessity of searching for more sophisticated methods of MRD evaluation and earlier diagnosis and treatment of relapse. The most often used methods are the fenotyping with flow cytometry and different types of qualitative and quantitative PCR. The merits and drawbacks of different method MRD evaluation are described.

Minimal Residual Disease Assessment in Multiple Myeloma Patients. Part II. Molecular Markers Analysis

Lipid Microdomain (Lipid Rafts) in Cell Membrane: Structure, Physiology and its Role in Pathological Processes

Summary: The classical bilayer model of cell membrane structure proposed by Singer and Nicholson in 1972 has recently been modified. Research has shown that lipid molecules in the membrane do not have a random horizontal distribution but form submicroscopic domain enriched in cholesterol, sphingolipids and gangliosides. These lipid microdomain (also named lipid rafts) have been visualised in living cells by a variety of methods including fluorescence microscopy with lipid-specific probes, scanning probe microscopy and cryoelectron microscopy. Rafts can be purified by ultracentrification and flotation techniques. Lipid rafts play a key functional role in cell metabolism by means of their association with a variety of important membrane molecules, including cytokine and growth factor receptors, death receptors or non-receptor protein kinases. In this paper we briefly review the role of lipid rafts in cell homeostasis and their pathogenic significance in infection diseases, cancer, chronic inflammation, diabetes and degenerative disorders of the central nervous system.

Key words: lipid rafts, cholesterol, gangliosides, plasma membrane, growth factor receptors

Summary: All organisms are exposed to reactive oxygen species such as hydrogen peroxide (H₂O₂), superoxide anion (O₂^·^-) and hydroxyl radical (^·OH) as unavoidable products of oxidative metabolism. Many biotic and abiotic factors such as: pathogens, air pollutants, salts, xenobiotic, heavy metals, UV radiation initiate ROS formation. The main sites of ROS formation in plant cells are chloroplasts, peroxisomes and mitochondria. ROS can cause wide-ranging damage to many macromolecules including proteins, lipids and nucleic acids, eventually leading to cell death. Recently considered positive biological roles of ROS act as signal-transducting molecules. To minimize the damaging effects of ROS, aerobic organisms evolved several antioxidant defense mechanisms, including catalase, superoxide dismutase, peroxidases and alternative oxidase, and non-enzymatic molecules such as: ascorbic, glutathione, homoglutathione, cysteine.

Summary: Cell death, commonly recognized as necrosis or apoptosis, is thought to be a one of biological processes describing cell life. The phenomena of cell recycling during human life is known for a various types of cells and the resistance of cancer cells to apoptosis is also well described. Proapoptotic gene therapy is one of the method of cancer therapy. The main rationales are focused on induction of apoptosis of cancer cells and therefore inhibition its growth. Mostly, gene therapy trials are concerned on genes encoding well known proteins of apoptotic signaling as BAX, P53, TNF, caspases. Proapoptotic gene therapy is also discussed as a supplementary method of the cancer treatment. The classical therapies like chemiotherapy or radiotherapy may be assisted by gene transfer strategy.

Summary: Synucleins are a family of small (15–20 kDa), soluble, conserved proteins that are predominantly expressed in neurons and include a-, b-, c-Synuclein and Synoretine. Among the synuclein family exclusively a-Synuclein is the precursor protein for highly hydrophobic 35-amino acid peptide NAC (non-amyloid b component of Alzheimer’s disease plaques). This presynaptic protein associated with synaptic vesicles is also present in cytosol. Under physiological conditions a-Synuclein is natively unfolded. Cellular function of this protein is till know poorly understood, however, several lines of evidence suggest its potential role in regulation of synaptic function, neuronal plasticity, as well as cell survival. Physiological functions of this protein are disturbed by its aggregation. Posttranslational modification, oxidative stress or catabolism defects can promote its aggregation and deposition in cells in the form of Lewy bodies. Aggregated form of a-Synuclein could be involved in cell death in several neurodegenerative disorders, including Parkinson’s disease, subtype of Alzheimer’s disease with Lewy bodies, as well as in dementia with Lewy bodies. The understanding of processes responsible for a-Synuclein aggregation and NAC liberation is very important for the elucidation of pathomechanism of several neurodegenerative diseases and their effective therapy.

Summary: Until very recently, erythrocytes have been considered unable to undergo apoptosis, as they lack mitochondria and nuclei, key organelles in the apoptotic machinery of other cells. However, in most recent observations it does not seem to be the truth.The major spinning point in this research was finding caspases (cysteine proteases), that play the major role in programmed cell death, in humans mature erythrocytes. This article shows the progress of apoptosis in different stadia of humans erythrocytes developement as well as in several pathological stadia. With regard to the evolutionary aspect the programmed cell death in erythrocytes of amphibians, reptiles, birds and mammals was also discussed.

Summary: Cord blood is alternative source of the haematopoietic stem cells (HSC) in relation to bone marrow and peripheral blood. Advantage of the cord blood (CB) is its relative accessibility as a source of HSC. HSC of CB present bigger proliferative potential than HSC of bone marrow and peripheral blood. Moreover they evoke weaker GvH reaction. The disadvantage of CB is its small amount obtainable once for all. It can be applied to allogenic transplantation only, although, the banking of CB is becoming popular as a source of HSC for future autologous transplantation. However, it is not proved that HSC after many years of banking will be as good for transplantation as freshly obtained. Quite a number of publications suggest that CB can be a source of stem cells other than haematopoietic, such as: neurogenic, cardiomyogenic, mezechymal, hepatogenic and precursors of Langerhans islets of pancreas. Yet, not all accept the results of those investigations.