The role of lipid rafts in vesicle formation

The formation of membrane vesicles is a common feature in all eukaryotes. Lipid rafts are the best-studied example of membrane domains for both eukaryotes and prokaryotes, and their existence also is suggested in Archaea membranes. Lipid rafts are involved in the formation of transport vesicles, endocytic vesicles, exocytic vesicles, synaptic vesicles and extracellular vesicles, as well as enveloped viruses. Two mechanisms of how rafts are involved in vesicle formation have been proposed: first, that raft proteins and/or lipids located in lipid rafts associate with coat proteins that form a budding vesicle, and second, vesicle budding is triggered by enzymatic generation of cone-shaped ceramides and inverted cone-shaped lyso-phospholipids. In both cases, induction of curvature is also facilitated by the relaxation of tension in the raft domain. In this Review, we discuss the role of raft-derived vesicles in several intracellular trafficking pathways. We also highlight their role in different pathways of endocytosis, and in the formation of intraluminal vesicles (ILVs) through budding inwards from the multivesicular body (MVB) membrane, because rafts inside MVB membranes are likely to be involved in loading RNA into ILVs. Finally, we discuss the association of glycoproteins with rafts via the glycocalyx.

Role of RNA Motifs in RNA Interaction with Membrane Lipid Rafts: Implications for Therapeutic Applications of Exosomal RNAs

RNA motifs may promote interactions with exosomes (EXO-motifs) and lipid rafts (RAFT-motifs) that are enriched in exosomal membranes. These interactions can promote selective RNA loading into exosomes. We quantified the affinity between RNA aptamers containing various EXO- and RAFT-motifs and membrane lipid rafts in a liposome model of exosomes by determining the dissociation constants. Analysis of the secondary structure of RNA molecules provided data about the possible location of EXO- and RAFT-motifs within the RNA structure. The affinity of RNAs containing RAFT-motifs (UUGU, UCCC, CUCC, CCCU) and some EXO-motifs (CCCU, UCCU) to rafted liposomes is higher in comparison to aptamers without these motifs, suggesting direct RNA-exosome interaction. We have confirmed these results through the determination of the dissociation constant values of exosome-RNA aptamer complexes. RNAs containing EXO-motifs GGAG or UGAG have substantially lower affinity to lipid rafts, suggesting indirect RNA-exosome interaction via RNA binding proteins. Bioinformatics analysis revealed RNA aptamers containing both raft- and miRNA-binding motifs and involvement of raft-binding motifs UCCCU and CUCCC. A strategy is proposed for using functional RNA aptamers (fRNAa) containing both RAFT-motif and a therapeutic motif (e.g., miRNA inhibitor) to selectively introduce RNAs into exosomes for fRNAa delivery to target cells for personalized therapy.

[Acute compartment syndrome in clinical toxicology]

In this article we described the basic information about diagnosis and treatment of acute compartment syndrome (acs). Rhabdomyolysis caused by standstill position, intramuscular injections of different xenobiotics, and hypo- and hyperthermia is the most common cause of acs among acute poisoned patients. The diagnosis may based on physical examination and direct measurement of tissue pressure. Treatment include prevention, and symptomatic therapy. In case of lack respond to symptomatic treatment the fasciotomy is needed.

[Minor head injury in children--proposed algorithm for clinical management]

AIM

Objective analysis of clinical and epidemiological aspects of minor head injuries in children with an attempt to elaborate a practical algorythm for diagnostic management.

MATERIAL AND METHODS

All children aged 3 to 18 years with minor head injury treated in the years 2005-2006 in the Department of Paediatric Surgery and Traumatology in Grudziadz, were included in a prospective study. In all, 884 children were enrolled into this analysis. Their medical data were reviewed with an emphasis on circumstances of injury, clinical signs and symptoms, diagnostic and therapeutic management its evaluation and final outcome.

RESULTS

Loss of consciousness and/or postinjury amnesia were noted in 88 patients (9.3%). Skull x-ray carried out in 486 children revealed bone fracture in 4 cases. 473 (53.5%) children were hospitalised, while 411 (46.5%) were discharged after initial examination for home the care. Among 82 children who had computed tomography, intracranial pathology was found in 17. None of the patients from either group required surgical intervention and all were discharged in a good condition.

CONCLUSIONS

From clinical point of view, it seems relevant to separate the group of patients with minimal head injury requiring no diagnostic study and hospitalization. Loss of consciousness and posttraumatic amnesia in children with minor injury should be treated as an indication for computed tomography and/or observation of the patient in hospital. The role of conventional x-ray in minor head injury is minimal. The presented practical diagnostic algorythm for children with minor head trauma, treated in emergency departments in Poland appears to be fully justified and important.

Behavior of sperm nuclei in intact and bisected metaphase II mouse oocytes fertilized in the presence of colcemid

Our objective was to examine the developmental fate of sperm nuclei in oocytes fertilized under conditions of meiotic arrest. Therefore zona-free metaphase II oocytes and oocyte fragments (nucleate and anucleate) were fertilized in the presence of colcemid. In anucleate oocyte fragments, normal male pronuclei develop. In contrast, in intact oocytes and nucleate fragments sperm nuclei after initial decondensation undergo secondary condensation. This state is maintained as long as the oocytes are treated with colcemid. When the drug is removed 3 h after insemination, the meiotic spindle(s) is reconstructed, the second polar body(ies) is extruded, and a female pronucleus (or micronuclei) forms. At the same time the sperm nucleus decondenses again and transforms into a male pronucleus. In addition oocytes fertilized in the presence of colcemid could not be refertilized. These observations suggest that oocytes and oocyte fragments fertilized in the presence of colcemid undergo activation despite the failure of pronucleus formation. The inhibitory effect of colcemid on the formation of pronuclei is expressed only in the presence of oocyte chromosomes. We suggest that colcemid stabilizes factors responsible for chromosome condensation that are associated with oocyte chromosomes but not factors (whether the same or different) present in the cytoplasm.