[Molecular mechanism of hereditary spherocytosis].

Hereditary spherocytosis (HS) is a common inherited anaemia in northern Europe characterized by the presence of spherocytic red cells and by heterogeneous clinical presentation, and heterogeneous molecular basis and inheritance. The primary molecular defects reside in the red blood cell membrane, particularly in proteins involved in the vertical interactions between the membrane skeleton and the lipid bilayer. Defects in these interactions lead to the loss of red cell surface area and to the spheroidal shape of the erythrocyte in particular loss of the membrane elasticity and mechanical stability.

Spectrin-phospholipid interactions. Existence of multiple kinds of binding sites?

The object of this paper is to review briefly the studies on the interactions of erythroid and non-erythroid spectrins with lipids in model and natural membranes. An important progress on the identification of lipid-binding sites has recently been made although many questions remain still unanswered. In particular, our understanding of the physiological role of such interactions is still limited.

(AC)n microsatellite polymorphism and 14-nucleotide deletion in exon 42 ankyrin-1 gene in several families with hereditary spherocytosis in a population of South-Western Poland.

Defects in ankyrin-1 have been implicated in approximately half of all patients with hereditary spherocytosis. However, not all polymorphisms in this gene lead to the changes in expressed protein or to the changes of the level of its expression. In this study, we report on several cases of the (AC)n microsatellite polymorphism in 3' untranslated region of ANK1 gene found in nine families (19 patients) with hereditary spherocytosis (HS) and also in ten healthy individuals from the same territory.

PS exposure increases the susceptibility of cells to fusion with DOTAP liposomes.

Cationic liposomes are used as efficient carriers for gene delivery into mammalian cells due to their ability to bind nucleic acids, adsorb onto the cell surface and fuse with negatively charged membranes. This last property enables the release and escape of their cargo from endosomal compartments. The efficiency of this fusion mainly depends on the surface charge of the target membranes.

ESR and monolayer study of the localization of coenzyme Q10 in artificial membranes.

The data obtained from the ESR experiments show a complex, depth dependent effect of CoQ10 on the lipid molecules mobility in the bilayer. These effects depend both on its concentration and the temperature. CoQ10 disturbs not only the hydrophobic core of the membrane but also the region close to the hydrophilic headgroups of phospholipids.

Cholesterol affects spectrin-phospholipid interactions in a manner different from changes resulting from alterations in membrane fluidity due to fatty acyl chain composition.

We previously showed that erythrocyte and brain spectrins bind phospholipid vesicles and monolayers prepared from phosphatidylethanolamine and phosphatidylserine and their mixtures with phosphatidylcholine (Review: A.F. Sikorski, B.

The effect of PS content on the ability of natural membranes to fuse with positively charged liposomes and lipoplexes.

Supramolecular aggregates containing cationic lipids have been widely used as transfection mediators due to their ability to interact with negatively charged DNA molecules and biological membranes. First steps of the process leading to transfection are partly electrostatic, partly hydrophobic interactions of liposomes/lipoplexes with cell and/or endosomal membrane. Negatively charged compounds of biological membranes, namely glycolipids, glycoproteins and phosphatidylserine (PS), are responsible for such events as adsorption, hemifusion, fusion, poration and destabilization of natural membranes upon contact with cationic liposomes/lipoplexes.

9-(2,6-Difluorophenoxycarbonyl)-10-methylacridinium trifluoromethanesulfonate and its precursor 2,6-difluorophenyl acridine-9-carboxylate: C-H...O, C-F...pi, S-O...pi and pi-pi stacking interactions.

The title compounds, C21H14F2NO2+.CF3SO3-, (I), and C20H11F2NO2, (II), form monoclinic and triclinic crystals, respectively. Adjacent cations of (I) are oriented in a ;head-to-tail' manner and are linked to one another via networks of C-H.

Star-branched polymers in an adsorbing slit: a Monte Carlo study.

A coarse-grained model of star-branched polymer chains confined in a slit was studied. The slit was formed by two parallel impenetrable surfaces, which were attractive for polymer beads. The polymer chains were flexible homopolymers built of identical united atoms whose positions in space were restricted to the vertices of a simple cubic lattice.

Crystal structure of methyl 3-amino-2,3-dideoxy-beta-D-arabino-hexopyranoside. Stabilization of the crystal lattice by a double network of N-H...O, O-H...N and O-H...O interactions.

The structure, conformation and configuration of methyl 3-amino-2,3-dideoxy-beta-D-arabino-hexopyranoside were investigated by (1)H NMR, (13)C NMR and IR spectroscopy, as well as by optical rotation. The crystal structure was confirmed by single-crystal X-ray crystallographic analysis at 293 K and R = 0.0434 based on 910 independent reflections.

Properties of star-branched and linear chains in confined space. A Monte-Carlo study.

We have studied the properties of simple models of linear and star-branched polymer chains confined in a slit formed by two parallel impenetrable walls. The polymer chains consisted of identical united atoms (homopolymers) and were restricted to a simple cubic lattice. Two macromolecular architectures of the chain: linear and regular stars with three branches of equal length, were studied.

Spectrin and calpain: a 'target' and a 'sniper' in the pathology of neuronal cells.

It is well documented that activation of calpain, a calcium-sensitive cysteine protease, marks the pathology of naturally and experimentally occurring neurodegenerative conditions. Calpain-mediated proteolysis of major membrane-skeletal protein, alphaII-spectrin, results in the appearance of two unique and highly stable breakdown products, which is an early event in neural cell pathology. This review focuses on spectrin degradation by calpain within neurons induced by diverse conditions, emphasizing a current picture of multi-pattern neuronal death and a recent success in the development of spectrin-based biomarkers.

Rafts--the current picture.

Although evidences that cell membrane contains microdomains are accumulating, the exact properties, diversity and levels of organization of small lipid patches built mainly of cholesterol and sphingomyelin, termed rafts, remain to be elucidated. Our understanding of the cell membrane is increasing with each new raft feature discovered. Nowadays rafts are suggested to act as sites of cell signaling events, to be a part of protein sorting machinery but also they are used by several pathogens as gates into the cells.

Proteins with spectrin motifs which do not belong to the spectrin-alpha-actinin-dystrophin family.

Using several consensus sequences for the 106 amino acid residue alpha-spectrin repeat segment as probes we searched animal sequence databases using the BLAST program in order to find proteins revealing limited, but significant similarity to spectrin. Among many spectrins and proteins from the spectrin-alpha-actinin-dystrophin family as well as sequences showing a rather high degree of similarity in very short stretches, we found seven homologous animal sequences of low overall similarity to spectrin but showing the presence of one or more spectrin-repeat motifs. The homology relationship of these sequences to alpha-spectrin was further analysed using the SEMIHOM program.

Repeated injections of PEG-PE liposomes generate anti-PEG antibodies.

Liposomes containing the polyethylene glycol (PEG) derivative of phosphatidyl ethanolamine (PE) have recently been found to be promising drug carriers, as they facilitate controlled and target-oriented release of therapeutics. They also reduce the side effects of many drugs. Here, we present the results of a study on antiliposomal properties of rabbit sera obtained after weekly injections of small liposomes containing 20% PEG-PE.

Computer simulation of polypeptide translocation through a nanopore.

A simplified model of polypeptide chains was designed and studied by means of computer simulations. Chains were represented by a sequence of united atoms located at the positions of the alpha-carbons. A further assumption was the lattice approximation for the chains.

9-(2,6-dichlorophenoxycarbonyl)-10-methylacridinium trifluoromethanesulfonate and its precursor 2,6-dichlorophenyl acridine-9-carboxylate.

The title compounds, C21H14Cl2NO2+.CF3O3S-, (I), and C20H11Cl2NO2, (II), form triclinic crystals. Adjacent cations of (I) are oriented either parallel or antiparallel; in the latter case, they are related by a centre of symmetry.

9-(2-Chloroethylamino)acridine monohydrate and its precursor 9-phenoxyacridine.

The title compounds, C15H13ClN2.H2O, (I), and C19H13NO, (II), form monoclinic crystals. Arranged in a 'head-to-tail' manner, the molecules of the amine form (I) lie along the b axis in layers that are linked by a network of hydrogen bonds involving the endocyclic N atom, the H atom at the exocyclic N atom and all the atoms of the solvent water molecule.

2-Ethylphenyl acridine-9-carboxylate and 2,5-dimethylphenyl acridine-9-carboxylate.

The title compounds, 2-ethylphenyl acridine-9-carboxylate, C22H17NO2, (I), and 2,5-dimethylphenyl acridine-9-carboxylate, C22H17NO2, (II), form triclinic and monoclinic crystals, respectively. Related by a centre of symmetry, adjacent molecules of (I) are linked in the lattice via a network of C-H..

Nuclear Pedigree Criteria for the Identification of Individuals Suspected to be at Risk of an Inherited Predisposition to Renal Cancer.

Renal clear cell carcinomas represent about 3% of all visceral cancers and account for approximately 85% of renal cancers in adults. Environmental and genetic factors are involved in the development of renal cancer. Although to date there are 19 hereditary syndromes described in which renal cell cancer may occur, only four syndromes with an unequivocal genetic predisposition to renal cell carcinoma have been identified: VHL syndrome (mutations in the VHL gene), hereditary clear cell carcinoma (translocations t(3:8), t(2:3)), hereditary papillary carcinoma (mutations in the MET protooncogene) and tuberous sclerosis (mutations in the TSC1 and TSC2 genes).

Synthesis, crystal structure, and high-resolution NMR spectroscopy of methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-xylo-hexopyranoside.

Synthesis of methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl- and -6-O-p-tolylsulfonyl-alpha-D-xylo-hexopyranosides is presented. High-resolution 1H and 13C NMR spectral data for both compounds and their precursors, and the single-crystal X-ray diffraction analysis for methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-xylo-hexopyranoside are reported. The influence of the O-protective group on the chemical shift of adjacent atoms in the 1H and 13C NMR spectra is discussed.

Changes in spectrin organisation in leukaemic and lymphoid cells upon chemotherapy.

The aim of the present study was to investigate changes in spectrin and protein kinase C theta; (PKC theta;) organisation in human lymphoid and leukaemic cells undergoing chemotherapeutically induced apoptosis. An analysis of spectrin arrangement in human peripheral lymphoid (non-Hodgkin lymphoma) and leukaemic (acute lymphoblastic leukaemia) cells before and after chemotherapy revealed radical differences in the distribution of this protein. By using immunofluorescent technique, in lymphocytes isolated before chemotherapy, we found spectrin evenly distributed in the cytoplasm and the plasma membrane, while after the therapy changes in spectrin organisation occurred.

Properties of branched confined polymers.

A model of star-branched polymer chains confined in a slit formed by two parallel surfaces was studied. The chains were embedded to a simple cubic lattice and consisted of f=3 branches of equal length. The macromolecules had the excluded volume and the confining surfaces were impenetrable for polymer segments.

Mapping of an ankyrin-sensitive, phosphatidylethanolamine/phosphatidylcholine mono- and bi-layer binding site in erythroid beta-spectrin.

It has been shown previously that binding of vesicles and monolayers containing PE (phosphatidylethanolamine) by either erythroid or non-erythroid spectrin proved sensitive to inhibition by purified erythrocyte ankyrin. We tested the lipid-binding affinities of the purified ankyrin-binding domain of beta-spectrin and of its truncated mutants in four ways, by analysing: (1) penetration of 'loose' PE/PC (phosphatidylcholine) monolayers; (2) binding to liposomes in suspension; (3) competition with spectrin for liposomes; and (4) binding of a PE/PC monolayer in a surface plasmon resonance system. The results obtained indicated that the full-length ankyrin-binding domain bound PE/PC mono- and bi-layers with moderate affinity, penetrated monolayers and competed with spectrin for liposomes.

A novel founder CHEK2 mutation is associated with increased prostate cancer risk.

Variants in the CHEK2 have been found to be associated with prostate cancer risk in the United States and Finland. We sequenced CHEK2 gene in 140 Polish patients with prostate cancer and then genotyped the three detected variants in a larger series of prostate cancer cases and controls. CHEK2 truncating mutations (IVS2 + 1G>A or 1100delC) were identified in 9 of 1921 controls (0.