RYBP represses endogenous retroviruses and preimplantation- and germ line-specific genes in mouse embryonic stem cells

Polycomb repressive complexes (PRCs) are important chromatin regulators of embryonic stem (ES) cell function. RYBP binds Polycomb H2A monoubiquitin ligases Ring1A and Ring1B and has been suggested to assist PRC localization to their targets. Moreover, constitutive inactivation of RYBP precludes ES cell formation. Using ES cells conditionally deficient in RYBP, we found that RYBP is not required for maintenance of the ES cell state, although mutant cells differentiate abnormally. Genome-wide chromatin association studies showed RYBP binding to promoters of Polycomb targets, although its presence is dispensable for gene repression. We discovered, using Eed-knockout (KO) ES cells, that RYBP binding to promoters was independent of H3K27me3. However, recruiting of PRC1 subunits Ring1B and Mel18 to their targets was not altered in the absence of RYBP. In contrast, we have found that RYBP efficiently represses endogenous retroviruses (murine endogenous retrovirus [MuERV] class) and preimplantation (including zygotic genome activation stage)- and germ line-specific genes. These observations support a selective repressor activity for RYBP that is dispensable for Polycomb function in the ES cell state. Also, they suggest a role for RYBP in epigenetic resetting during preimplantation development through repression of germ line genes and PcG targets before formation of pluripotent epiblast cells.     

Syntheses, structures, thermal behavior and solution studies of two types of Hg(II) complexes with [1,3-di(2-methoxy)benzene]triazene

The reaction of [1,3-di(2-methoxy)benzene]triazene, [HL], with Hg(CH₃COO)₂ and Hg(SCN)₂ in methanol as solvent, resulted in the formation of [HgL₂] (1) and [HgL(SCN)] (2), respectively. These compounds were characterized by means of X-ray diffraction, FT-IR spectroscopy, CHN and TGA-DTA analysis. In the lattice of the compound 1, the mono-nuclear complexes were connected to dimer structure by intermolecular non-classical C-H···O hydrogen bonds. Also, weak Hg-η²-arene π-interactions link the dimers into 1D supramolecular chains. The compound 2 is a 2D coordination polymer induced by C-H···π stacking interactions between 1D chains produced by weak Hg-η³-η³-arene π-interactions. The results of studies of the stoichiometry and formation of complexes of 1 and 2 in methanol solution were found to be in support of their solid state stoichiometry.     

Life history of the Western Crested Loach <Emphasis Type="Italic">Paracobitis malapterura</Emphasis> in the Zarrin-Gol River,East of the Elburz mountains (Northern Iran)

A total of 370 specimens of Paracobitis malapterura in the Zarrin-Gol River (east of the Elburz Mts, Iran) were caught by regular monthly collection throughout one year from November 2006 to October 2007. The specimens were then examined for age and growth, reproduction and feeding attributes. Based on otolith readings the maximum ages of the population observed were 3⁺ years for males and 4⁺ years for females. The specimens ranged in size from 38 to 130 mm total length, weighing from 0.68 to 30.55 g total weight. Length-weight relationship was estimated as W = 0.020L ^2.62 for males, W = 0.002L ^3.81 for females and W = 0.008L ^3.08 for the population. Sex ratio was 1: 1.27 in favor of females. The Gonadosomatic index indicated that reproduction of the loach in the river occurred around April–May, with the highest average value of 1.48 for males and of 5.36 for females in May. The absolute fecundity ranged between 92–1180 eggs with a mean of 456.31 eggs. Diameter of oocytes ranged from 0.11 to 2.80 mm with a mean value of 0.95 mm. The absolute fecundity and oocyte diameter to fish size (length and weight) and age were not significantly correlated. Plecoptera and Trichoptera dominated the diet contents composing 72.43% and 20.80% of total frequency of food items, respectively.     

Evaluation of Oxidative Stress, Antioxidant Status and Serum Vitamin C Levels in Cancer Patients

Taking into account the importance role of lipid peroxidation and antioxidants in the prevention and incidence of cancer, the present study was carried out to determine oxidative stress, serum total antioxidant (TAS), and vitamin C levels in cancer patients. Malondialdehyde(MDA), total antioxidant status, and vitamin C levels of 57cancer patients aged 19–80 years and 22 healthy subjects (control group) aged 22–76 years were evaluated. Serum concentrations of MDA as thiobarbitaric acid complexes were measured by fluorometry method, the serum TAS by using commercial test kits from Randox Laboratories, and vitamin C by using spectrocolorimetric method. The mean serum MDA concentrations of all cancer groups except lung cancer were significantly higher than control group (P < 0.004). The mean total antioxidant status was insignificantly higher than control group. The mean serum vitamin C level was significantly lower in patients as compared to the healthy subjects (PV < 0.0001). In conclusion, an alteration in the lipid peroxidation with concomitant changes in antioxidant defense system in cancer patients may be due to excessive oxidative stress. Serum low levels of vitamin C in the different type of cancer patients in spite of adequate daily intake may be due to increased utilization to scavenge lipid peroxides as well as their sequestration by tumor cells.     

Simultaneous determination of triprolidine and pseudoephedrine in human plasma by liquid chromatography–ion trap mass spectrometry

A highly efficient, selective and specific method for simultaneous quantitation of triprolidine and pseudoephedrine in human plasma by liquid chromatography–ion trap-tandem mass spectrometry coupled with electro spray ionization (LC–ESI-ion trap-tandem MS) has been validated and successfully applied to a clinical pharmacokinetic study. Both targeted compounds together with the internal standard (gabapentin) were extracted from the plasma by direct protein precipitation. Chromatographic separation was achieved on a C₁₈ ACE^® column (50.0 mm × 2.1 mm, 5 μm, Advance Chromatography Technologies, Aberdeen, UK), using an isocratic mobile phase, consisting of water, methanol and formic acid (55:45:0.5, v/v/v), at a flow-rate of 0.3 mL/min. The transition monitored (positive mode) was m/z 279.1 → m/z 208.1 for triprolidine, m/z 165.9 → m/z 148.0 for pseudoephedrine and m/z 172.0 → m/z 154.0 for gabapentin (IS). This method had a chromatographic run time of 5.0 min and a linear calibration curves ranged from 0.2 to 20.0 ng/mL for triprolidine and 5.0–500.0 ng/mL for pseudoephedrine. The within- and between-batch accuracy and precision (expressed as coefficient of variation, %C.V.) evaluated at four quality control levels were within 94.3–106.3% and 1.0–9.6% respectively. The mean recoveries of triprolidine, pseudoephedrine and gabapentin were 93.6, 76.3 and 82.0% respectively. Stability of triprolidine and pseudoephedrine was assessed under different storage conditions. The validated method was successfully employed for the bioequivalence study of triprolidine and pseudoephedrine formulation in twenty six volunteers under fasting conditions.     

The functional consequences of paraoxon exposure in central neurones of land snail, Caucasotachea atrolabiata, are partly mediated through modulation of Ca2+ and Ca2+-activated K+-channels

Toxicity of paraoxon has been attributed to inhibition of cholinesterase, but little is known about its direct action on ionic channels. The effects of paraoxon (0.3 microM-0.6 microM) were studied on the firing behaviour of snail neurones. Paraoxon significantly increased the frequency of spontaneously generated action potentials, shortened the afterhyperpolarization (AHP) and decreased the precision of firing. Short periods of high frequency-evoked trains of action potentials led to an accumulation in the depth and duration of post-train AHPs that was evidenced as an increase in time to resumption of autonomous activity. The delay time in autonomous activity initiation was linearly related to the frequency of spikes in the preceding train and the slope of the curve significantly decreased by paraoxon. The paraoxon induced hyperexcitability and its depressant effect on the AHP and the post-train AHP were not blocked by atropine and hexamethonium. Calcium spikes were elicited in a Na+ free Ringer containing voltage dependent potassium channel blockers. Paraoxon significantly decreased the duration of calcium spikes and following AHP and increased the frequency of spikes. These findings suggest that a reduction in calcium influx during action potential may decrease the activation of calcium dependent potassium channels that participate in AHP generation and act as a mechanism of paraoxon induced hyperexcitability.     

Synthesis and antimycobacterial evaluation of various 7-substituted ciprofloxacin derivatives

Tuberculosis continues to be a major cause of morbidity and mortality all over the world. Various 7-substituted ciprofloxacin derivatives were synthesized and evaluated for antimycobacterial activity in vitro and in vivo against Mycobacterium tuberculosis and for inhibition of the supercoiling activity of DNA gyrase from Mycobacterium smegmatis. Preliminary results indicated that most of the compounds demonstrated better in vitro antimycobacterial activity against M. tuberculosis than ciprofloxacin. Compound 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-[[N4-[1'-(5-methylisatinyl-beta-semicarbazo)]methyl]N1-piperazinyl]-3-quinoline carboxylic acid (3h) decreased the bacterial load in spleen tissue with 0.76-log10 protections and was considered to be moderately active in reducing bacterial count in spleen. The results demonstrated the potential and importance of developing new quinolone derivatives against mycobacterial infections.     

Short-term changes in prostacyclin secretory profile of irradiated rat cervical spinal cord

Prostaglandins changes in radiation myelopathy (RM) have been previously reported. In the present study, we decided to determine the profile of Prostacyclin (PGI2) content in irradiated rat cervical cord. Wistar rats were irradiated with doses of 2,4,6,15,25 and 30 Gy of X-rays. After 24 h, 2 and 13 weeks post-irradiation, samples of spinal cord were prepared for evaluation of PGI2 and histopathologic changes. Prostacyclin content was determined by quantification of 6-keto-prostaglandin-F1alpha (prostacyclin major metabolite). Irradiated segments of spinal cord were stained routinely for histological studies. Results of irradiated were compared to control groups. Average ratio values of 6-keto-PG-F1alpha for doses of 2-30 Gy were between 67.5% and 107%, 65.41% and 100.54%, and 62.20% and 98.89% for 24 h, 2 and 13 weeks post-irradiation, respectively. Histopathological studies showed marked gliosis and vascularities in irradiated specimens. PGI2 bimodal secretory profile was observed along with histopathological changes in this study. Our results can further emphasize on the role of PGI2 in RM.     

Intermedilysin is essential for the invasion of hepatoma HepG2 cells by Streptococcus intermedius

Streptococcus intermedius causes endogenous infections leading to abscesses. This species produces intermedilysin (ILY), a human-specific cytolysin. Because of the significant correlation between higher ILY production levels by S. intermedius and deep-seated abscesses, we constructed ily knockout mutant UNS38 B3 and complementation strain UNS38 B3R1 in order to investigate the role of ILY in deep-seated infections. Strain UNS38 reduced the viability of human liver cell line HepG2 at infection but not of rat liver cell line BRL3A. Isogenic mutant strain UNS38 B3 was not cytotoxic in either cell line. Quantification of S. intermedius revealed that in infected HepG2 cells UNS38 but not UNS38 B3 increased intracellularly concomitantly with increasing cell damage. This difference between UNS38 and UNS38 B3 was not observed with UNS38 B3R1. Invasion and proliferation in BRL3A cells was not observed. Masking UNS38 or UNS38 B3R1 with ILY antibody drastically decreased adherence and invasion of HepG2. Moreover, coating strain UNS38 B3 with ILY partially restored adherence to HepG2 but without subsequent bacterial growth. At 1 day post-infection, many intact UNS38 were detected in the damaged phagosomes of HepG2 with bacterial proliferation observed in the cytoplasm of dead HepG2 after an additional 2 day incubation. These results indicate that surface-bound ILY on S. intermedius is an important factor for invasion of human cells by this bacterium and that secretion of ILY within host cells is essential for subsequent host cell death. These data strongly implicate ILY as an important factor in the pathogenesis of abscesses in vivo by this streptococcus.     

Reduction of diabetes-induced oxidative stress by phosphodiesterase inhibitors in rats

Increased oxidative stress has been suggested to be involved in the pathogenesis and progression of diabetic tissue damage. The aim of this study was to investigate the effect of different phosphodiesterase inhibitors on lipid peroxidation and total antioxidant capacity (TAC) of plasma in streptozotocin-induced diabetic rats (Rattus norvegicus). Rats became diabetic by a single administration of streptozotocin (STZ, 45 mg/kg). The effects of 15-days treatment by milrinone, sildenafil, and theophylline as cyclic-AMP and -GMP phosphodiesterase inhibitors (PDEIs) on diabetes-induced oxidative stress were studied. The levels of glucose, malonedialdehyde (MDA) the by product of lipid peroxides, and TAC (FRAP test) were estimated in plasma of control and experimental groups of rats. A significant increase in the levels of plasma glucose, and MDA and a concomitant decrease in the levels of TAC were observed in diabetic rats. These alterations were reverted back to near normal level after the treatment with PDEIs. Treatment of diabetic rats by PDEIs reduced MDA levels and increased TAC in the order of milrinone>sildenafil>theophylline. In conclusion, the present investigation show that PDIS possesses antioxidant activities, which may be attributed to their enhancing effect on cellular cyclic nucleotides contributing to the protection against oxidative stress in streptozotocin-induced diabetes. Exact mechanism of protective actions of cAMP- and cGMP-phosphodiesterase remains to be elucidated by further studies. This finding may suggest a place for PDEIs in maintaining health in diabetes.