Suppression of generalized seizures activity by intrathalamic 2-chloroadenosine application

In the present study, we investigated the effects of micro-injecting 2-chloroadenosine (2-CADO; an adenosine receptor agonist) into the thalamus alone and with theophylline (a nonspecific adenosine receptor antagonist) pretreatment on pentylenetetrazol (PTZ)-induced tonic-clonic seizures in male Wistar albino rats. Following intrathalamic 2-CADO injection alone or theophylline pretreatment, 50 mg kg(-1) PTZ was given ip after 1 and 24 hrs. The duration of epileptic seizure activity was recorded by cortical electroencephalogram (EEG), and seizure severity was behaviorally scored. Intrathalamic 2-CADO administration induced significant decreases in both seizure duration and seizure severity scores at 1 and 24 hrs, but the effects were more abundant on the seizures induced after 24 hrs. On the other hand, pretreatment with theophylline prevented the inhibitor effect of 2-CADO on seizure activity and increased both seizure duration and seizure scores. Present results suggest that the activation of adenosine receptors in the thalamus may represent another anticonvulsant/modulatory site of adenosine action during the course of the PTZ-induced generalized tonic-clonic seizures and provide additional data for the involvement of the adenosinergic system in the generalized seizures model.     

A New Method for Purification of Carbonic Anhydrase Isozymes by Affinity Chromatography

A new affinity gel for purification of carbonic anhydrase isozymes was prepared using EUPERGIT C-250L derivatized with p-aminobenzenesulfonamide, an inhibitor of carbonic anhydrase. The binding capacity of the affinity gel was determined at different temperatures, pH values, elution buffers, and ionic strengths. Human carbonic anhydrase isozymes (HCA I and HCA II) and bovine carbonic anhydrase (BCA) were purified in high yields from erythrocytes.     

Type II Fatty Acid Biosynthesis, a New Approach in Antimalarial Natural Product Discovery

Malaria, one of the most problematic infectious diseases worldwide, is on the rise. The absence of an effective vaccine and the spread of drug-resistant strains of Plasmodium clearly indicate the necessity for the development of new chemotherapeutic agents and the identification of novel targets. The recent discovery of a relict, non-photosynthetic plastid-like organelle, the so-called apicoplast, in Plasmodium has opened up new avenues in malaria research. It also initiated the Plasmodium falciparum genome sequencing project, which revealed a number of biochemical pathways previously unknown to Plasmodium, i.e. cytosolic shikimate pathway, apicoplastic type II fatty acid, non-mevalonate isoprene and haem biosyntheses. Since these vital biosynthetic processes are absent in humans or fundamentally different from those found in humans, they represent excellent targets for pharmaceutical interventions. We are interested in the type II fatty acid synthase (FAS II) system of malaria parasite and focus on the FabI enzyme, the only known enoyl-ACP reductase in Plasmodium involved in the final reduction step of the fatty acid chain elongation cycle. Here we describe the general aspects of fatty acid biosynthesis, its essentiality to the malaria parasite and our continuing efforts to discover in Turkish medicinal plants natural antimalarial agents, which specifically target the plasmodial FabI enzyme.Phytochemical Society of Europe (PSE)-Pierre Fabre Prize 2004 Lecture     

Molecular epidemiology of penicillin resistantStreptococcus pneumoniae strains in Turkey. A multicenter study

A total of 539 isolates recovered from various clinical sites were collected from 13 hospitals from different regions of Turkey between 1999 and 2002. Susceptibility to penicillin and cefotaxime was determined by the E-test and the remaining antimicrobials were evaluated by disk diffusion tests. Penicillin resistant and intermediate isolates were serotyped and PFGE patterns were analysed. Overall 16 isolates (3%) were resistant to penicillin, and 143 (26.5%) were intermediate. Resistance and intermediate rates were 3.1% and 29.0% respectively in respiratory tract isolates. Multiple resistance (resistance to ≥3 antibiotics) occurred in 81.8% of the penicillin resistant isolates and the most frequent resistance phenotype was penicillin+trimethoprim/sulphamethoxazole (37.7%). Minimum inhibitory concentrations of cefotaxime were lower than 1 mg/ml for all the isolates. The highest rate of resistance was observed for trimethoprim/ sulphamethoxazole (26.6%) followed by doxycycline (12.6%). Resistance to erythromycin was 10.1%, clindamycin 9.9%, chloramphenicol 4.3%, ofloxacin 5.0% and levofloxacin 0.2%. There was no resistance to vancomycin. Resistant isolates belonged to serogroups 9, 23, and 6. The most frequent serogroups among intermediate isolates were 23, 19, 14, 1, 9, and 6. Five distinct PFGE patterns were observed among penicillin resistant isolates. There was no distinct clustering of specific PFGE patterns in the study centres. No correlation between serotypes, resistance and PFGE patterns was found. There seems to be genetic heterogeneity inStreptococccus pneumoniae isolates in Turkey.     

Atomistic simulation of nanomechanical properties of Alzheimer’s Aβ(1–40) amyloid fibrils under compressive and tensile loading

In addition to being associated with severe degenerative diseases, amyloids show exceptional mechanical properties including great strength, sturdiness and elasticity. However, thus far physical models that explain these properties remain elusive, and our understanding of molecular deformation and failure mechanisms of individual amyloid fibrils is limited. Here we report a series of molecular dynamics simulations, carried out to analyze the mechanical response of two-fold symmetric Aβ(1–40) amyloid fibrils, twisted protein nanofilaments consisting of a H-bonded layered structure. We find a correlation of the mechanical behavior with chemical and nanostructural rearrangements of the fibril during compressive and tensile deformation, showing that the density of H-bonds varies linearly with the measured strain. Further, we find that both compressive and tensile deformation is coupled with torsional deformation, which is manifested in a strong variation of the interlayer twist angle that is found to be proportional to both the applied stress and measured strain. In both compression and tension we observe an increase of the Young's modulus from 2.34 GPa (for less than 0.1% strain in compression and 0.2% strain in tension), to 12.43 GPa for compression and 18.05 GPa for tension. The moduli at larger deformation are in good agreement with experimental data, where values in the range of 10–20 GPa have been reported. Our studies confirm that amyloids feature a very high stiffness, and elucidate the importance of the chemical and structural rearrangements of the fibrils during deformation.     

The Lbc Rho Guanine Nucleotide Exchange Factor/α-Catulin Axis Functions in Serotonin-induced Vascular Smooth Muscle Cell Mitogenesis and RhoA/ROCK Activation

Serotonin (5-hydroxytryptamine, 5-HT) is mitogenic for several cell types including pulmonary arterial smooth muscle cells (PASMC), and is associated with the abnormal vascular smooth muscle remodeling that occurs in pulmonary arterial hypertension. RhoA/Rho kinase (ROCK) function is required for 5-HT-induced PASMC mitogenesis, and 5-HT activates RhoA; however, the signaling steps are poorly defined. Rho guanine nucleotide exchange factors (Rho GEFs) transduce extracellular signals to Rho, and we found that 5-HT treatment of PASMC led to increased membrane-associated Lbc Rho GEF, suggesting modulation by 5-HT. Lbc knockdown by siRNA attenuated 5-HT-induced thymidine uptake in PASMC, indicating a role in PASMC mitogenesis. 5-HT triggered Rho-dependent serum response factor-mediated reporter activation in PASMC, and this was reduced by Lbc depletion. Lbc knockdown reduced 5-HT-induced RhoA/ROCK activation, but not p42/44 ERK MAP kinase activation, suggesting that Lbc is an intermediary between 5-HT and RhoA/ROCK, but not ERK. 5-HT stimulation of PASMC led to increased association between Lbc, RhoA, and the α-catulin scaffold. Furthermore, α-catulin knockdown attenuated 5-HT-induced PASMC thymidine uptake. 5-HT-induced PASMC mitogenesis was reduced by dominant-negative G_q protein, suggesting cooperation with Lbc/α-catulin. These results for the first time define a Rho GEF involved in vascular smooth muscle cell growth and serotonin signaling, and suggest that Lbc Rho GEF family members play distinct roles. Thus, the Lbc/α-catulin axis participates in 5-HT-induced PASMC mitogenesis and RhoA/ROCK signaling, and may be an interventional target in diseases involving vascular smooth muscle remodeling.     

The effect of cysteine and glutathione on sperm and oxidative stress parameters of post-thawed bull semen

The aim of this study was to determine the effects of antioxidants such as reduced glutathione (GSH) and cysteine in Laiciphose® extender on semen parameters, fertilizing ability, lipid peroxidation (LPO) level and glutathione peroxidise (GPx) activity of post-thawed bull semen. Totally 54 ejaculates of three bulls were used in the study. Five groups, namely; GSH (0.5 and 2 mM), cysteine (5 and 10 mM) and control group, were conducted to test the antioxidants in Laiciphose®. Insemination doses were processed that each 0.25-mL straw contained 15 × 10⁶ sperm. The addition of antioxidants did not present any significant effect on the percentages of post-thaw sperm morphology (acrosome and total abnormalities), subjective, CASA and progressive motilities, as well as sperm motility characteristics (VAP, VSL, VCL, LIN and ALH), compared to the control groups (P > 0.05). GSH 0.5 mM (55.5 ± 7.38%) and cysteine 10 mM (48 ± 5.65%) led to lower rates of DNA damage, compared to control (P < 0.05). As regards to MDA level, cysteine at 10 mM dose gave the highest level (4.99 ± 0.44 nmol/L) (P < 0.001). GPx activity was demonstrated to be higher level upon the addition of 5 mM cysteine when compared to the other groups (P < 0.05). With respect to fertility results based on 60-day non-returns, the supplementation of antioxidants did not present significant differences (P > 0.05). The results of this study may provide an useful information for the future studies in this area. So, further studies could be suggested to achieve better information in terms of the DNA damage and fertilizing capacity of bull sperm frozen with effective antioxidants.     

The effect of levamisole and levamisole + vitamin C on oxidative damage in rats naturally infected with Syphacia muris

This study was performed to determine the effects of levamisole and levamisole + vitamin C against Syphacia muris naturally infection in rats and to detect its effect on the oxidative parameters in blood and tissues of host. For this purpose, natural infection was diagnosed using the cellophane tape method on the perianal region of rats. Infected rats (total 18) were divided into three groups. On the other hand six without helminth rats were used in this study as negative control group. Group 2 was given an orally levamisole HCl treatment with gastric gavage at a dose level of 20 mg/kg body weight in distilled water, every alternate day. Group 3 was given levamisole HCl via gastric gavage at a dose level of 20 mg/kg and vitamin C was given 1 g/L added to the drinking water. All the treatments continued for a period of 7 days. As a result; levamisole administered to rats at dose of 20 mg/kg orally 98.34% was found to be effective against adult S. muris in the rats. In addition to levamisole + vitamin C is effective to alleviate the oxidative damage in rats infected with S. muris.     

Effects of Thymus kotschyanus var. glabrescens Boiss. extract on mitomycin-C induced chromosomal aberrations and sister chromatid exchanges in human lymphocytes

In this investigation, clastogenic effects of Thymus kotschyanus var. glabrescens Boiss. extract (TE) and anticlastogenic effects of this extract against Mitomycin C (MMC) induced chromosome damage have been evaluated in human peripheral blood lymphocytes in vitro. Two series of experiments were conducted. In the first, only 10⁻⁵, 10⁻⁴, 10⁻³ and 10⁻² μl ml⁻¹ concentrations of TE were used for 48 h to detect potential clastogenicity. In the second, MMC (0.38 μg ml⁻¹) plus 10⁻⁵, 10⁻⁴, 10⁻³ and 10⁻² μl ml⁻¹ concentrations of TE were used for 48 h to determine anticlastogenic effects. TE did not increase sister chromatid exchanges (SCEs) (except 10⁻² μl ml concentration) and chromosome aberrations (CAs) significantly compared with negative and solvent controls. However, it decreased the frequency of MMC induced chromosome aberrations. Decreasing was significant at 10⁻⁴, 10⁻³ and 10⁻² μl ml⁻¹ concentrations. On the other hand, TE significantly increased MMC-induced SCEs for all treatment groups compared with positive control.