Distribution of N-cadherin in human cerebral cortex during prenatal development

An important subgroup of adhesion molecules is the superfamily of cadherins, which takes part in cell recognition and differentiation during development. To our knowledge only one study describing N-cadherin expression in developing human brain has been performed so far. Our aim is to identify N-cadherin expression to establish a relationship between its expression and function in human cerebral cortex during prenatal development. In the present study, localization and intensity of N-cadherin was investigated in developing cerebral cortex. Fetuses from spontaneous abortions (n=13) were obtained from first, second, and third trimesters. Western blot analysis revealed three bands and the third trimester samples showed the strongest bands for N-cadherin. Cell processes, axon bundles, and some of the developing neurons revealed immunoreactivity for N-cadherin throughout pregnancy. The immunoreactivity increased in the developing neocortex and expanded from the ventricular layer toward the marginal zone as development progressed. Moreover, the immunoreactivity was strong in vascular endothelium during all three trimesters. We conclude that N-cadherin is dynamically related to the organization of cerebral cortex layers during prenatal development. The dynamic expression pattern implicates N-cadherin as a potential regulator of cell migration, axon extension and fasciculation, the establishment of synaptic contacts, and neurovascular angiogenesis in the developing human cerebral cortex.     

Effect of Iloprost on endothelin-1-induced free radical activation in rabbit brain stem

Iloprost, a stable analogue of prostacyclin, was used to reverse the early period of vasoconstriction provoked by Endothelin-1 by administering into the rabbit basilar artery. We observed if this produced an effect on the central nervous system parenchyma mediated by free radical system. The red neurons were counted in brain stem sections stained with haematoxylin and eosin, while superoxide dismutase and malondialdehyde levels were measured in brain stem tissue samples as a marker of reactive oxygen metabolites; both 30 and 90 min after administration of either Endothelin-1 (0.25 ng) alone or Endothelin-1 followed by Iloprost (0.5 microg/kg) into the basilar artery. Endothelin-1 significantly increased the number of red neurons, while Iloprost significantly reduced them after 30 and 90 min. However, regarding the reactive oxygen metabolites; a similar reversing effect of Iloprost was not observed although superoxide dismutase levels were significantly decreased after Endothelin-1 infusion.     

Minimally invasive method for murine brain fixation

Complete brain fixation can be achieved with transthoracic cardiac infusion without thoracotomy. Light and electron microscopy tissue sections reveal preservation of cytoplasmic and nuclear structure at all magnification levels. Punched samples were obtained from the fixed tissue specimens in precisely localized areas for study using electron microscopy. This perfusion fixation technique provides both faster tissue harvesting capability and higher quality tissue preservation, without the artifacts of brain swelling and ventricular dilation observed in direct cardiac perfusion. Acute, discrete change in brain tissue can be studied.     

PTEN-mediated Akt activation in human neocortex during prenatal development

Akt is a crucial factor for cell survival and migration. Phosphatase and tensin (PTEN) negatively regulates cell growth and survival by inhibiting PI3K-dependent signaling. PTEN also blocks Akt phosphorylation, a main downstream molecule of PI3K cascade. So far, no studies have shown PTEN expression and Akt phosphorylation levels in the developing human neocortex. Our hypothesis is that spatial and temporal expression of PTEN is likely to modulate developing human brain cortical modeling by regulating Akt activation. Therefore, our aim is to analyze the expression pattern of PTEN and phospho-Akt levels using immunohistochemistry, Western blot, and semiquantitative analysis in the developing human neocortex (n=13 fetuses from first, second, and third trimesters). PTEN expression was decreased parallel to development, but some cells revealed strong nuclear immunoreactivity in the developing neocortex while the active Akt level was increased. Double immunohistochemistry was performed for proliferating cell nuclear antigen (PCNA)-Tuj1 (as neuronal marker) and PCNA-GFAP (Glial marker) to the subsequent sections of PTEN and Akt-stained slides. PCNA (+) cells were mostly positive for glial fibrillary acidic protein (GFAP) and correlated with active-Akt immunoreactivity. Our results suggest that Akt-mediated signaling plays an active role in cell migration, survival, and cerebral cortical modeling throughout prenatal life and that PTEN is the most likely protein to regulate this signaling.     

Pseudohypericin and hyperforin in two Turkish Hypericum species: Variation among plant parts and phenological stages

The genus Hypericum has received considerable interest from scientists, as it contains the variety of structurally diverse natural products which possess a wide array of biological properties, mainly hypericins and hyperforin. In the present study, variations of pseudohypericin and hyperforin were investigated in two Turkish species of Hypericum, namely Hypericum perfoliatum and Hypericum origanifolium. Wild growing plants were harvested at vegetative, floral budding, flowering, fresh fruiting and mature fruiting stages, and dissected into stem, leaf and reproductive tissues and assayed for chemical contents by high performance liquid chromatography method. Content of pseudohypericin and hyperforin in samples of the whole plant increased during the course of ontogenesis in both species. The highest levels of the chemicals were reached at full flowering (2.62 mg/g dry weight (DW) pseudohypericin and 1.84 mg/g DW hyperforin for H. perfoliatum; 0.93 mg/g DW pseudohypericin and 1.63 mg/g DW hyperforin for H. origanifolium). Among different reproductive parts, full opened flowers produced the highest amount of pseudohypericin (1.18 mg/g DW) and hyperforin (4.36 mg/g DW) in H. origanifolium. Similarly, the highest pseudohypericin accumulation was observed in full opened flowers in H. perfoliatum (7.41 mg/g DW) while floral buds of this species produced the highest amount of hyperforin (7.80 mg/g DW). These data can be useful when elucidating the medicinal properties of the species and the chemosystematic significance of hyperforin and pseudohypericin in the relationships among species of Hypericum.     

Effect of Strontium Ranelate on Hydrogen Peroxide-Induced Apoptosis of CRL-11372 Cells

In vitro and in vivo studies have proven strontium to be an osteoinductive trace element. The effect of strontium ranelate (SR) on H₂O₂-induced apoptosis of CRL-11372 cells and optimization of its anti-apoptotic dose were the aims of this study. After 1 h of pretreatment with SR 1 μM, 50 μM, 100 μM, 500 μM, and 1,000 μM concentrations, CRL-11372 osteoblasts were exposed to 100 μM H₂O₂ for periods of 6–12 h. The same experiments were repeated without H₂O₂. The apoptotic index and viability of cells were assessed quantitatively with a fluorescent dye and qualitatively with agarose gel electrophoresis. Concentrations of 1–100 μM of SR with a 6-h treatment and only 1 μM concentration with a 12-h treatment inhibited the apoptotic effect of H₂O₂ on cultured osteoblasts significantly (P < 0.05). SR was shown to inhibit H₂O₂-induced apoptosis of CRL-11372 cells in a dose-dependent manner.     

Extracellular Synthesis and Characterization of Gold Nanoparticles Using <Emphasis Type="Italic">Mycobacterium</Emphasis> sp. BRS2A-AR2 Isolated from the Aerial Roots of the Ghanaian Mangrove Plant, <Emphasis Type="Italic">Rhizophora racemosa</Emphasis>

Through the use of genomes that have undergone millions of years of evolution, marine Actinobacteria are known to have adapted to rapidly changing environmental pressures. The result is a huge chemical and biological diversity among marine Actinobacteria. It is gradually becoming a known fact that, marine Actinobacteria have the capability to produce nanoparticles which have reasonable sizes and structures with possible applications in biotechnology and pharmacology. Mycobacterium sp. BRS2A-AR2 was isolated from the aerial roots of the mangrove plant Rhizophora racemosa. The Mycobacterium was demonstrated for the first time ever to produce AuNPs with sizes that range between 5 and 55 nm. The highest level absorbance of the biosynthesized AuNPs was typical for actinobacterial strains (2.881 at 545 nm). The polydispersity index was measured as 0.207 in DLS and the zeta potential was negatively charged (? 28.3 mV). Significant vibration stretches were seen at 3314, 2358, 1635 and 667 cm^?1 in FT-IR spectra. This demonstrated the possible use of small aliphatic compounds containing –COOH, –OH, –Cl and –NH₂ functional groups in the stabilization of the AuNPs. The effect of the biosynthesized AuNPs on HUVEC and HeLA cell lines was measured at 48 h. IC₅₀ values were determined at 3500 µg/ml concentration for HUVEC and HeLA cell lines at 45.25 and 53.41% respectively.     

Nuclear morphometric features of epithelial cells lining keratocysts

OBJECTIVE: To investigate the nuclear morphometric features of epithelial cells lining keratocysts and some other odontogenic cysts. STUDY DESIGN: All cases were selected from the archives of the Department of Pathology, Gülhane Military Medical Academy, as follows: 20 keratocysts and 10 dentigerous and 10 radicular cysts. Nuclear morphometric variables were measured on hematoxylin and eosin-stained histologic slides. Basal and intermediate cells of the epithelium were evaluated separately. Nuclei of the cells were outlined interactively and measured using a specially written macro program. Area, feret ratio (ratio of the longest nuclear axis to the shortest one) and circularity (F circle) of the nuclei were calculated. Additionally, nuclear densitometric analysis was performed on the keratocyst cases. RESULTS: The number of cells in the basal layer (cell density) was higher in keratocysts than in other cysts. The mean nuclear area of basal cells was smaller than of intermediate cells in both keratocysts and other cysts (P < .001). The feret ratio values revealed that basal cell nuclei of keratocysts were more ovoid as compared to those of other cysts (P < .001). Nuclear densitometric findings showed that the DNA indices of all keratocyst cases were close to 1.0, and the cells were considered diploid. CONCLUSION: Increased cell density, a more ovoid nuclear shape and more variation in the size of basal layer cell nuclei in keratocysts were helpful in differentiating these lesions from other odontogenic cysts.