Functional inactivation of the rat hippocampus disrupts avoidance of a moving object

The hippocampus is well known for its critical involvement in spatial memory and information processing. In this study, we examined the effect of bilateral hippocampal inactivation with tetrodotoxin (TTX) in an "enemy avoidance" task. In this paradigm, a rat foraging on a circular platform (82 cm diameter) is trained to avoid a moving robot in 20-min sessions. Whenever the rat is located within 25 cm of the robot's center, it receives a mild electrical foot shock, which may be repeated until the subject makes an escape response to a safe distance. Seventeen young male Long-Evans rats were implanted with cannulae aimed at the dorsal hippocampus 14 d before the start of the training. After 6 d of training, each rat received a bilateral intrahippocampal infusion of TTX (5 ng in 1 μL) 40 min before the training session on day 7. The inactivation severely impaired avoidance of a moving robot (n = 8). No deficit was observed in a different group of rats (n = 9) that avoided a stable robot that was only displaced once in the middle of the session, showing that the impairment was not due to a deficit in distance estimation, object-reinforcement association, or shock sensitivity. This finding suggests a specific role of the hippocampus in dynamic cognitive processes required for flexible navigation strategies such as continuous updating of information about the position of a moving stimulus.     

Two sporadic infected cardiac myxomas in 1 patient

Infected cardiac myxoma is a rare cause of endocarditis. The finding of coexisting infected cardiac myxomas is highly unusual. Herein, we present the case of a 58-year-old woman with a low-grade fever. Laboratory findings strongly indicated inflammation, and blood cultures detected Staphylococcus species. Echocardiograms revealed mobile masses in the area of the mitral valve. Transesophageal echocardiograms showed 2 formations that arose from opposite sides of the mitral annulus and protruded into the left ventricle during systole. During emergency surgery, 2 abnormal growths with numerous vegetations were completely excised. The diagnosis of myxoma was confirmed upon histologic evaluation. Microbiological and polymerase chain reaction analysis of the myxomas detected the bacterial strain Enterococcus faecalis. Five months postoperatively, the patient showed no signs of recurrent infection and had a normal echocardiographic appearance.This report is the first of an infected cardiac myxoma in the Czech population and one of approximately 60 reports in the medical literature from 1956 to the present. In addition to the case of our patient, we discuss the discrepancy between the bacteriologic findings.     

Chromosome aberrations induced in human lymphocytes by U-235 fission neutrons

Aim

Further experiments were performed to explain a difference in chromosomal aberration yield found between samples cultivated immediately after fission neutron irradiation and samples which were cultivated with 96 h delay after irradiation.

Material and Method

Human peripheral blood samples were irradiated in mixed fission neutron/gamma field (1800 s) and biological effect assessed in the mean of analysis of unstable chromosome aberrations with a time delay in culturing cells of 12, 24, 48, and 96 h. Additional measurements were performed on irradiated and blank blood samples with the aim to detect any increase in α and β activity after fission neutron irradiation. No difference was found. Results were compared to theoretically calculated values of the α and β activity released from natural radioactive isotopes.

Result and Conclusion

As a conclusion it is shown that in our experimental conditions the secondary effects resulting from nuclear transformations of natural or induced radioactive isotopes, recoil reactions and accompanying α, β, and γ radiation are not the reason for the increase observed in chromosomal aberration yield in blood samples cultured with a time delay of at least 24 hours.     

Nanovehicular intracellular delivery systems

This article provides an overview of principles and barriers relevant to intracellular drug and gene transport, accumulation and retention (collectively called as drug delivery) by means of nanovehicles (NV). The aim is to deliver a cargo to a particular intracellular site, if possible, to exert a local action. Some of the principles discussed in this article apply to noncolloidal drugs that are not permeable to the plasma membrane or to the blood-brain barrier. NV are defined as a wide range of nanosized particles leading to colloidal objects which are capable of entering cells and tissues and delivering a cargo intracelullarly. Different localization and targeting means are discussed. Limited discussion on pharmacokinetics and pharmacodynamics is also presented. NVs are contrasted to micro-delivery and current nanotechnologies which are already in commercial use. Newer developments in NV technologies are outlined and future applications are stressed. We also briefly review the existing modeling tools and approaches to quantitatively describe the behavior of targeted NV within the vascular and tumor compartments, an area of particular importance. While we list "elementary" phenomena related to different level of complexity of delivery to cancer, we also stress importance of multi-scale modeling and bottom-up systems biology approach.     

Shape optimization and characterization of polysaccharide beads prepared by ionotropic gelation

The shape of drug loaded polysaccharide beads produced by ionotropic gelation has been optimized, with the aim of producing spherical beads suitable for further technological operations, such as coating. The optimization was performed on a model system sodium alginate/theophylline by inclusion of various fillers. Incorporation of excipients markedly influenced the morphological characteristics of the beads. The undesired irregular shape of beads caused by incorporation of the drug could only be improved by incorporating a combination of polycarbophil (PK) and polyvinylpyrrolidone (PVP). The spherical shape of these beads was stabilized mechanically by numerous air bubbles trapped inside the beads, which prevented the collapse of the beads during drying. The optimized method was shown to be applicable to a target system of pectin and an anti-inflammatory drug, LK-423.