Neuroprotective Agents: Is Effective on Toxicity in Glial Cells?

1. Glial cells are the most abundant cell population in the central nervous system. The aim of this study was to examine the effects of melatonin, 7-nitroindazole, and riluzole on glutamate toxicity in primary glial cell culture. 2. Glutamate toxicity was induced by addition of 100 μM glutamate to the cultures, and then 100 μM melatonin, 500 μM 7-nitroindazole, and 10 (M riluzole were administered in different groups. Lactate Dehydrogenase activity and nitrite levels were determined at the 1st, 6th, and 24th h. 3. Melatonin, 7-nitroindazole, and riluzole decrease Lactate Dehydrogenase activity at the 1st, 6th, and 24th h (at all hours, p<0.05). Nitrite levels were decreased by melatonin and riluzole at the 1st, 6th, and 24th h. 4. In this study, we observed that melatonin, 7-nitroindazole, and riluzole are effective as protective agents on glutamate toxicity in mixed glial cells.     

The influence of continuous exposure to 50 Hz electric field on nerve regeneration in a rat peroneal nerve crush injury model

The effect of power frequency electric field (EF) on nerve regeneration was investigated on a rat peroneal nerve crush injury model. The animals were assigned to three groups: 50 Hz EF and Static EF groups were exposed at 10 kV/m. The sham group was kept in the same setting without any EF applications. EF was uninterruptedly applied for 21 days postoperatively. Repeated measures analysis of daily walking tracks during EF exposure demonstrated lower toe spread recovery (TSR) in the 50 Hz EF group. Significant difference across the groups was found only at days 7, 8, 12, 16, 17, 20, and 21 when TSR was analyzed for each measurement time. Print length recovery and peroneal function index did not differ across the groups. Walking track parameters were found to recover to their baseline values by day 28 in all groups. Day 14 but not day 21 measurements revealed smaller nerve cross-sectional area, lower total regenerating axon area, and higher mean myelin debris area in 50 Hz EF group. Both day 14 and 21 measurements revealed higher total myelin debris area, lower EDL muscle weight, and lack of significant enlargement in nerve cross-section distal to the injury, compared to the normal counterpart in 50 Hz EF group. All differences were in keeping with lower rates of Wallerian degeneration and nerve regeneration in 50 Hz EF group. When walking track, histomorphometry and muscle weight are considered individually, their differences across the groups may appear to be subtle to derive a conclusion for a 50 Hz EF effect. However, their concordance with each other in direction of effect suggests that continuous 50 Hz EF exposure has a weak effect that is detrimental mostly to the rate of early nerve regeneration in this axonotmetic injury model. Recovery of walking tracks was not different between Static EF and Sham groups. This suggests that the surface charges that may indirectly affect walking behaviors of the rats, do not account for the lower recovery of TSR in 50 Hz EF group. Differences in nerve regeneration between 50 Hz EF and Static EF groups suggests that electric induction may be required for pure EF effects even though the estimated density of induced fields is not above the endogenous background level for the 50 Hz EF exposure in this study.     

On the excited-state energy transfer between tryptophan residues in proteins: the case of penicillin acylase

The problem, whether excited-state energy transfer occurs between Trp residues in a multi-tryptophan proteins and if it does, what kind of changes it induces in different parameters of protein fluorescence, is currently under active investigation. In our previous paper [Biophys. Chem. 72 (1998) 265], the energy transfer was found and studied in detail for Na,K-ATPase. It was shown that this transfer influences all parameters of fluorescence emission, which is detected at site-selective conditions (red-edge of excitation, blue and red edges of emission). Present experiments were performed on unusually tryptophan-rich protein, bacterial penicillin acylase (28 Trp per dimer of 82 kDa) and were aimed to extend these observations. They demonstrate substantial heterogeneity in the environments of tryptophan residues within the protein structure. This suggests, that in the present case, if the energy transfer exists, it should be directed from short-wavelength-emitting to long-wavelength-emitting tryptophan residues and thus could be easily observed by a number of time-resolved and steady-state fluorescence techniques. Unexpectedly, no signature of inter-tryptophan energy transfer was found.     

Effects of the calcium channel blocker amlodipine on serum and aortic cholesterol,lipid peroxidation,antioxidant status and aortic histology in cholesterol-fed rabbits

Reactive oxygen metabolites and oxidized fatty acids are proinflammatory and are involved in the pathophysiology of atherosclerosis. Amlodipine, a unique third-generation dihydropyridine-type calcium channel blocker, seems to exert atheroprotective effects through its antioxidant properties related to its chemical structure and independent of its calcium channel-blocking effect. In this study, the interactions of amlodipine with major cellular antioxidants were investigated in order to elucidate the mechanisms underlying its atheroprotective effects. New Zealand white male rabbits were fed regular chow (group 1), chow with 1% cholesterol (group 2), regular chow plus 5 mg/kg/day amlodipine per os (group 3) and 1% cholesterol plus amlodipine (group 4) for 8 weeks. Total cholesterol, malondialdehyde (MDA) and vitamin E concentrations and catalase and superoxide dismutase (SOD) activities were determined in blood drawn before and after the experimental period. Aortic tissue was examined for atherosclerotic changes and aortic total cholesterol, MDA, catalase and SOD were determined. At the end of the 8-week treatment period, serum total cholesterol and plasma MDA were elevated in groups 2 and 4. In group 2, serum vitamin E and plasma SOD diminished (p < 0.05) and catalase increased (p < 0.05). In group 4, SOD activity increased at the end of treatment. MDA levels were lower and plasma SOD activities were higher in group 4 than in group 2. Aortic tissue investigations revealed higher total cholesterol and MDA concentrations and catalase activities in group 2 than in group 4, and the highest tissue SOD activity was recorded in group 4 (p < 0.05 for all comparisons). Morphological examination of aortic tissues exhibited endothelial disarrangement and lipid deposition in group 2. Histopathological alterations related to atherogenesis were less in group 4 than in group 2. Amlodipine seems to exert atheroprotective effects by reducing aortic cholesterol accumulation and blood and aortic lipid peroxidation, enhancing SOD activity both in blood and aortic tissue and suppressing the consumption of vitamin E. On the other hand, the suppression of catalase activity in blood and the aorta interferes with the drug's well-known antioxidant effects.     

Morphology and chemical composition of metathoracic scent glands in Dolycoris baccarum (Linnaeus, 1758) (Heteroptera: Pentatomidae)

One of the general defining characters of the Heteroptera is the presence of metathoracic scent glands (MTG). Using scanning electron microscopy, the morphology of the MTG of Dolycoris baccarum (Linnaeus 1758) (Heteroptera: Pentatomidae) was studied. The MTG belong to the diastomian type. The two glandular pores located between the mesothoracic and metathoracic coxae are associated with 'mushroom-like' structures. The MTG are composed of a reservoir and a pair of lateral glands is connected to the reservoir by a duct. A groove-like structure extends downwards from the ostiole. While this structure is long and wide, its ostiole is oval. Extracts of the volatile fractions from male and female MTG secretions were analysed by capillary gas chromatography–mass spectrometry (GC-MS) and exhibited a typical pentatomid composition. Seventeen chemical compounds were detected in female secretions, whereas 13 chemical compounds were detected in the male secretions. Most chemical compounds were similar between the sexes but were different in their quantities. In this regard, the compounds identified were investigated and the biological functions of the glandular secretions were discussed. In the analyses of the MTG of females of D. baccarum , tridecane (50.97%) was a major odour component and (Z,Z)-4,16-octadecadien-1-ol acetate (0.02%) was a minor odour component. In males, tridecane (50.80%) was a major odour component and 1,2-benzenedicarboxylic acid (0.02%) was a minor odour component.     

Are we aware how contaminated our mobile phones with nosocomial pathogens?

Vibrio spp. is a pathogen rarely isolated in cancer patients, and in most cases it is associated with haematological diseases. Cutaneous manifestations of this organism are even rarer. We report a case of Non-O1 Vibrio cholerae inguinal skin and soft tissue infection presenting bullous skin lesions in a young type II diabetic patient with a penis squamous cell carcinoma having a seawater exposure history.     

Effect of Putrescine on Low-Temperature Acclimation in <i>Chlamydomonas reinhardtii</i>

Putrescine is reported to be necessary for cold acclimation under low-temperature stress. In this study, the effect of low-temperature on some physiological and biochemical parameters has been investigated using the green algae Chlamydomonas reinhardtii. The lipid peroxidation rate, amount of Rubisco protein, activities of antioxidant enzymes and gene expression of polyamine biosynthesis (odc2, and spd1), heat shock proteins (hsp70c, hsp90a, and hsp90c), and PSII repair mechanisms (psba, rep27, and tba1) were determined to understand the low-temperature response. Exogenous putrescine application significantly increased Rubisco protein concentration and catalase enzyme activities under low-temperature stress. Moreover, real-time RT-PCR results and gene expression analysis showed that polyamine metabolism induced gene expression at low-temperatures in the first 24 h. In the same way, the gene expression of heat shock proteins (hsp70c, hsp90a, and hsp90c) decreased under low-temperature treatment for 72 h; however, application of putrescine enhanced the gene expression in the first 24 h. The results obtained indicated that molecular response in the first 24 h could be important for cold acclimation. The psba and tba1 expressions were reduced under low-temperatures depending on the exposure time. In contrast, the exogenous putrescine enhanced the expression level of the psba response to low-temperature at 24 and 72 h. The results obtained in this study indicate that putrescine could play a role in the PS II repair mechanisms under low-temperature stress.     

Investigation of extracellular medium osmolality depending on zinc application and incubation time on A549 cancer cells

Changes in the osmolality of the extracellular medium (ECM) affect cell volume and cellular processes such as cell migration and proliferation. Not only may high concentrations of zinc (Zn) lead to cell death by apoptosis, but Zn is also a physiological suppressor of apoptosis. The aim of our study was to examine whether Zn and regulation of extracellular osmolality had an effect on the lung cancer cell line (A549) and how to be changed in ECM according to elements and osmolality depending on incubation time and Zn application. Our study consisted of four groups: cell-free medium, ECM of cancer cell after 24 h incubation (24hECM), ECM of cancer cell after 48 h incubation (48hECM), and ECM of cancer cell after 48 h incubation with ZnCl₂ (48hECM?+?Zn). ECM osmolality was measured by using osmometer, and the levels of chromium (Cr), iron (Fe), and magnesium (Mg) elements were analyzed using ICP-OES device for all groups. According to the result of the analysis, a statistically significant difference was found when osmolality and element values of ECM of 24hECM and 48hECM groups were compared with the values of the 48hECM?+?Zn group. It was observed that there was a decrease in the levels of Cr, Fe, and Mg with Zn application and incubation period in ECM. The regulation of ECM osmolality is a promising method due to biophysical effects on cancer cells. In our study, we speculated that the understanding of the effects of Zn and osmolality with the relationship between ECM and cancer cell might lead to the discovery of biophysical approaches as a novel therapeutic strategy.

     

CK2-dependent C-terminal phosphorylation at T300 directs the nuclear transport of TSPY protein

TSPY (testis-specific protein, Y-encoded) is a member of the greater SET/NAP family of molecules with various functions, e.g., in chromatin remodeling, regulation of gene expression, and has been implicated to play a role in the malignant development of gonadoblastoma, testicular and prostate cancer. Here we demonstrate that the C-terminus has a functional role for the nucleo-cytoplasmatic shuttling of the TSPY protein. Using various combinations of in vitro mutagenesis and enhanced green fluorescent protein reporter gene-expression experiments we were able to show that while the deletion of C-terminus leads to a decreased stability and enhanced degradation of the protein, the selective mutation of a C-terminal CK2 phosphorylation site (T300) prevents the TSPY protein from entering the nucleus. We conclude that phosphorylation of the (T300) residue is a necessary and functional prerequisite for TSPY's transport into the nucleus reminding of comparable data from a related Drosophila molecule, NAP1.     

Crystallographic structure of the tetratricopeptide repeat domain of Plasmodium falciparum FKBP35 and its molecular interaction with Hsp90 C‐terminal pentapeptide

Plasmodium falciparum FK506‐binding protein 35 (PfFKBP35) that binds to FK506 contains a conserved tetratricopeptide repeat (TPR) domain. Several known TPR domains such as Hop, PPP5, CHIP, and FKBP52 are structurally conserved and are able to interact with molecular chaperones such as Hsp70/Hsp90. Here, we present the crystal structure of PfFKBP35‐TPR and demonstrate its interaction with Hsp90 C‐terminal pentapeptide (MEEVD) by surface plasmon resonance and nuclear magnetic resonance spectroscopy‐based binding studies. Our sequence and structural analyses reveal that PfFKBP35 is similar to Hop and PPP5 in possessing all the conserved residues which are important for carboxylate clamping with Hsp90. Mutational studies were carried out on positively charged clamp residues that are crucial for binding to carboxylate groups of aspartate, showing that all the mutated residues are important for Hsp90 binding. Molecular docking and electrostatic calculations demonstrated that the MEEVD peptide of Hsp90 can form aspartate clamp unlike FKBP52. Our results provide insightful information and structural basis about the molecular interaction between PfFKBP35‐TPR and Hsp90.