Activity studies of glucose oxidase immobilized onto poly(N-vinylimidazole) and metal ion-chelated poly(N-vinylimidazole) hydrogels

Poly(N-vinylimidazole), PVIm, gels were prepared by γ-irradiation polymerization of N-vinylimidazole in aqueous solutions. These affinity gels with a water swelling ratio of 1800% for plain polymeric gel and between 30 and 80% for Cu(II) and Co(II)-chelated gels at pH 6.0 in phosphate buffer were used in glucose oxidase (GOx) adsorption–desorption studies. Different amounts of Cu(II) and Co(II) ions (maximum 3.64 mmol/g dry gel for Cu(II) and 1.72 mmol/g dry gel for Co(II)) were loaded onto the gels by changing the initial concentration of Cu(II) and Co(II) ions, and pH. GOx adsorption on these gels from aqueous solutions containing different amount of GOx at different pH was investigated in batch reactors. Immobilized glucose oxidase activity onto the poly(N-vinylimidazole), and Cu(II) and Co(II)-chelated poly(N-vinylimidazole) were investigated with changing pH and the initial glucose oxidase concentration. Maximum activity of immobilized glucose oxidase onto the PVIm, Cu(II) and Co(II)-chelated PVIm gels was investigated and pH dependence was observed to be at pH 6.5 for free enzyme, pH 7.0 for PVIm, pH 7.5 for Cu(II) and Co(II)-chelated PVIm gels, respectively. The stability of the immobilized enzyme is very high for all gels and the residual activity was higher than 93% in the first 10 days.     

Overexpression of MYC and EZH2 cooperates to epigenetically silence MST1 expression

Hippo-like MST1 protein kinase regulates cell growth, organ size, and carcinogenesis. Reduction or loss of MST1 expression is implicated in poor cancer prognosis. However, the mechanism leading to MST1 silencing remains elusive. Here, we report that both MYC and EZH2 function as potent suppressors of MST1 expression in human prostate cancer cells. We demonstrated that concurrent overexpression of MYC and EZH2 correlated with the reduction or loss of MST1 expression, as shown by RT-qPCR and immunoblotting. Methylation sensitive PCR and bisulfite genomic DNA sequencing showed that DNA methylation caused MST1 silencing. Pharmacologic and RNAi experiments revealed that MYC and EZH2 silenced MST1 expression by inhibiting its promoter activity, and that EZH2 was a mediator of the MYC-induced silencing of MST1. In addition, MYC contributed to MST1 silencing by partly inhibiting the expression of microRNA-26a/b, a negative regulator of EZH2. As shown by ChIP assays, EZH2-induced DNA methylation and H3K27me3 modification, which was accompanied by a reduced H3K4me3 mark and RNA polymerase II occupancy on the MST1 promoter CpG region, were the underlying cause of MST1 silencing. Moreover, potent pharmacologic inhibitors of MYC or EZH2 suppressed prostate cancer cell growth in vitro, and the knockdown of MST1 caused cells’ resistance to MYC and EZH2 inhibitor-induced growth retardation. These findings indicate that MYC, in concert with EZH2, epigenetically attenuates MST1 expression and suggest that the loss of MST1/Hippo functions is critical for the MYC or EZH2 mediation of cancer cell survival.     

Aneurysm and Helicobacter pylori relationship: the seropositivity of CagA, VacA and other antigens of Helicobacter pylori in abdominal and ascending aortic aneurysms

Helicobacter pylori is thought to be related to atherosclerosis and aneurysm development. We aimed to detect virulance factors of H. pylori and examine the potential etiopathogenetic relationship between aortic aneurysm and H. pylori, 58 abdominal aortic aneurysm (AAA) and 38 ascending aortic aneurysm (AsAA) cases and 57 Healty control group (HCG) were included. We investigated H. pylori IgG by ELISA and virulance factors by Western-Blot (WB) method. No difference was found between AAA (67.24%), AsAA (73.68%) and HCG (57.89%) for H. pylori IgG (p > 0.05). A significant difference was found between AsAA (78.95%) and HCG (57.89%) for H.pylori IgG (p < 0.05) by ELISA and a significant difference was found only between AsAA (100%) and HCG (37.5%) for H. pylori IgG in the 45-55 age group by WB. A statistically significant difference was found between AAA and AsAA for VacA and CagA + VacA and CagA + VacA + UreA antigens and also a significant difference was found between AsAA and HCG for CagA + UreA antigens (p < 0.05). Finally, we suggest that H. pylori VacA has a more important role than CagA in the development of two aneurysms especially in ruptured AAA. New extended studies detecting H. pylori DNA are needed to detect the aetiopathogenesis between aneurysm types and H. pylori.     

An assessment of fertility in boron-exposed turkish subpopulations

Summary In order to assess the effects of boron and its compounds on human health in a country with the world’s largest deposits, investigations were carried out on fertility and reproduction in the most highly exposed populations. The 927 probands, 697 male and 230 female, interviewed in the field were selected from six different areas of Turkey, in the provinces of Balikesir, Eskisehir, and Kutahya, with the highest boron deposits. These people are exposed to boron environmentally or occupationally or both. The drinking waters of high-boron soils contain 0.7–29 mg B/L compared with 0.05-0.45 mg B/L of low-boron soils. By the so-called pedigree technique 5,934 marriages were ascertained over three generations from all study areas. Childless families among 911 probands were 29 in number and 3.17% in frequency with minor variations from one area to the next, and 3.0% averaged over the generations. Infertility rates in a boron-free community near Ankara with 625 families studied over three generations was 4.48%, and in a larger population of 49,856 families randomly investigated by us throughout the country was 3.84%. No significant differences were observed in terms of marital status and childbearing between 222 and 399 occupationally boron-unrelated and boron-related men, respectively. Nor was there any difference with respect to other aspects studied. It was concluded that, within the limitations of this study, there was no evidence that boron interferes with human fertility and reproduction.     

Covalent immobilization of acetylcholinesterase on a novel polyacrylic acid‐based nanofiber membrane

In this study, polyacrylic acid‐based nanofiber (NF) membrane was prepared via electrospinning method. Acetylcholinesterase (AChE) from Electrophorus electricus was covalently immobilized onto polyacrylic acid‐based NF membrane by demonstrating efficient enzyme immobilization, and immobilization capacity of polymer membranes was found to be 0.4 mg/g. The novel NF membrane was synthesized via thermally activated surface reconstruction, and activation with carbonyldiimidazole upon electrospinning. The morphology of the polyacrylic acid‐based membrane was investigated by scanning electron microscopy, Fourier Transform Infrared Spectroscopy, and thermogravimetric analysis. The effect of temperature and pH on enzyme activity was investigated and maxima activities for free and immobilized enzyme were observed at 30 and 35°C, and pH 7.4 and 8.0, respectively. The effect of 1 mM Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Mg²⁺, Ca²⁺ ions on the stability of the immobilized AChE was also investigated. According to the Michaelis–Menten plot, AChE possessed a lower affinity to acetylthiocholine iodide after immobilization, and the Michaelis–Menten constant of immobilized and free AChE were found to be 0.5008 and 0.4733 mM, respectively. The immobilized AChE demonstrated satisfactory reusability, and even after 10 consecutive activity assay runs, AChE maintained ca. 87% of its initial activity. Free enzyme lost its activity completely within 60 days, while the immobilized enzyme retained approximately 70% of the initial activity under the same storage time. The favorable reusability of immobilized AChE enables the support to be employable to develop the AChE‐based biosensors.     

The breeding biology of the White-spectacled Bulbul,Pycnonotus xanthopygos,at the northwestern edge of its distribution range

The White-spectacled Bulbul, Pycnonotus xanthopygos, is an abundant and possibly invasive species in Turkey, where it has gradually expanded its distribution and breeding range in both western and southeastern directions. This study focused on its breeding biology, which is still poorly known. The breeding activity extends from February until September. The preferred nesting areas are mainly gardens and maquis groves, where 24 different nesting tree species have been identified. The clutch size is 3.3 ± 0.8 eggs per pair, nesting success 68%, hatching success 94%, fledgling success 95%, and overall breeding success 89%. While nesting success differs significantly between the years, we found no significant differences in hatching, fledging, and overall breeding success between the years studied. Despite favourable climatic conditions in the Mediterranean region, the species makes only one brood per year in a relatively extended breeding season extending over seven months, and has a relatively a high reproduction rate per nest.     

Klasea serratuloides subsp. karamanica subsp. nov. (Asteraceae), from the central and south Anatolia transition zone,Turkey

A new subspecies, Klasea serratuloides (DC.) Greuter & Wagenitz subsp. karamanica B. Dogan & A. Duran (Asteraceae), is described and illustrated from Anatolia, Turkey. The subspecies grows on stony places in the Ayranc? and Ermenek district (C4 Karaman Province), Ere?li district (C5 Konya province) and Uluk??la (C5 Ni?de province) in the central and south Anatolia transition zone. It is morphologically similar to K. serratuloides subsp. serratuloides. Diagnostic morphological characters from closely similar taxa are discussed and arranged in a key. Ecology and conservation status of the subspecies is also presented. In addition, the geographical distribution of the new subspecies and other related species is mapped. The pollen morphology and achene surface of K. serratuloides subsp. karamanica and K. serratuloides subsp. serratuloides were examined by SEM.     

Boron Contents of Some Wild-Growing Mushrooms Collected from the Vicinity of Boron Mines in Balikesir,Turkey

The aim of the study was to determine the boron contents of some wild-growing mushrooms collected from the vicinity of several boron mines located in Balikesir, Turkey and compare the boron contents of some mushroom and soil samples. The locations of the mushroom samples collected were within the distance of 0–100, 100–500, and 500–1,000 m to the mines. Soil samples were taken from beneath randomly selected fungal fruit bodies. A total of 40 mushroom samples were found in the study area and 37 different species were identified. Among the 40 samples analyzed, the highest boron content was detected to be 273 mg kg⁻¹ in Suillus collinitus. Also, Tricholoma terreum (69.52 mg kg⁻¹), Myxomphalia maura (36.52 mg kg⁻¹), Otidea concinna (30.70 mg kg⁻¹), Sepultaria arenosa (28.94 mg kg⁻¹), Melanoleuca paedida (28.33 mg kg⁻¹), and Lycoperdon lividum (28.31 mg kg⁻¹) relatively have high levels of boron and these species are proposed as candidates for boron accumulation. The boron contents of the other mushrooms varied and a pattern was observed where the boron content was found to be decreased as the distance from the mines increased.