Synthesis and evaluation of antioxidant activity of new quinoline-2-carbaldehyde hydrazone derivatives: bioisosteric melatonin analogues

Overproduction of reactive oxygen species results in oxidative stress that can cause fatal damage to vital cell structures. It is known that the use of antioxidants could be beneficial in the prevention or delay of numerous diseases associated with oxidative stress. Melatonin (MLT) is known as a powerful free-radical scavenger and antioxidant. It was found that indole ring of MLT can be employed by bioisosteric replacement by other aromatic rings. Quinoline derivatives constitute an important class of compounds for new drug development. Owing to quinoline and hydrazones appealing physiological properties and are mostly found in numerous biologically active compounds a series of quinoline-2-carbaldehyde hydrazone derivatives were synthesized as bioisosteric analogues of MLT, characterized and in vitro antioxidant activity was investigated by evaluating their reducing effect against oxidation of a redox-sensitive fluorescent probe. Cytotoxicity potential of all compounds was investigated both by lactate dehydrogenase leakage assay and by MTT assay.     

Epigenetic regulation of insulin-like growth factor binding protein-3 (IGFBP-3) in cancer

Epigenetics refers to heritable changes in gene expression that are independent of alterations in DNA sequence. It is now accepted that disruption of epigenetic mechanisms plays a key role in the pathogenesis of cancer: culminating in altered gene function and malignant cellular transformation. DNA methylation and histone modifications are the most widely studied changes but non-coding RNAs such as miRNAs are also considered part of the epigenetic machinery. The insulin-like growth factor (IGF) axis is composed of two ligands, IGF-I and –II, their receptors and six high affinity IGF binding proteins (IGFBPs). The IGF axis plays a key role in cancer development and progression. As IGFBP genes have consistently been identified among the most common to be aberrantly altered in tumours, this review will focus on epigenetic regulation of IGFBP-3 in cancer for which the majority of evidence has been obtained.     

Specific role of Chk1 phosphorylations in cell survival and checkpoint activation

Chk1 is a multifunctional protein kinase that plays essential roles in cell survival and cell cycle checkpoints. Chk1 is phosphorylated at multiple sites by several protein kinases, but the precise effects of these phosphorylations are largely unknown. Using a knockout-knockin system, we examined the abilities of Chk1 mutants to reverse the defects of Chk1-null cells. Wild-type Chk1 could rescue all the defects of Chk1-null cells. Like endogenous Chk1, wild-type Chk1 localized in both the cytoplasm and the nucleus, and its centrosomal association was enhanced by DNA damage. The mutation at S345 resulted in mitotic catastrophe, impaired checkpoints, and loss of the ability to localize in the cytoplasm, but the mutant retained the ability to be released from chromatin upon encountering genotoxic stressors. In contrast, the mutation at S317 resulted in impaired checkpoints and loss of chromatin release upon encountering genotoxic stressors, but its mutant retained the abilities to prevent mitotic catastrophes and to localize in the cytoplasm, suggesting the distinct effects of these phosphorylations. The forced immobilization of S317A/S345A in centrosomes resulted in the prevention of apoptosis in the presence or absence of DNA damage. Thus, two-step phosphorylation of Chk1 at S317 and S345 appeared to be required for proper localization of Chk1 to centrosomes.     

Influence of perioperative whole blood transfusions on lymphocyte subpopulations in patients with stage II breast cancer

Preliminary reports have suggested an adverse relationship between blood transfusion and survival after surgery in patients with solid tumour. One might postulate that from these studies, perioperative blood transfusions alter host immune defences. We therefore examined the influence of homologous whole blood transfusion on circulating lymphocyte subpopulations in transfused patients compared with non-transfused patients. Fifty-one women with Stage II breast cancer who underwent surgical procedures were studied. Patients were classified into two groups on the basis of whether or not they had received blood transfusion. The lymphocyte subpopulations were analyzed by flow cytometry before cancer surgery and three weeks after the operation. CD3⁺, CD4⁺, CD8⁺, and CD20⁺ cells as the lymphocyte subsets were quantitated using appropriate monoclonal antibodies. No significant differences between pre- and postoperative lymphocyte subset levels were seen in non-transfused patients. However, there was a statistically significant increase in the CD8⁺ cell count; decreasing CD4⁺ cell count and decreased CD3⁺ cells levels were observed in the transfused group (P<0.05). Although these early results of the study suggest that the blood transfusions could be associated with alterations in lymphocyte populations, additional studies are needed to elucidate the possible mechanism of the transfusion-induced immunological modulations.     

The circadian disruption of night work alters gut microbiota consistent with elevated risk for future metabolic and gastrointestinal pathology

ABSTRACT

Day and night cycles are the most important cue for the central clock of human beings, and they are also important for the gut clock. The aim of the study is to determine the differences in the gut microbiota of rotational shift workers when working the day versus night shift. Fecal samples and other data were collected from 10 volunteer male security officers after 4 weeks of day shift work (07:00–15:00 h) and also after 2 weeks of night shift work (23:00–07:00 h). In total, 20 stool samples were collected for analysis of gut microbiota (10 subjects x 2 work shifts) and stored at ?80°C until analysis by 16 S rRNA sequencing. The relative abundances of Bacteroidetes were reduced and those of Actinobacteria and Firmicutes increased when working the night compared to day shift. Faecalibacterium abundance was found to be a biomarker of the day shift work. Dorea longicatena and Dorea formicigenerans were significantly more abundant in individuals when working the night shift. Rotational day and night shift work causes circadian rhythm disturbance with an associated alteration in the abundances of gut microbiota, leading to the concern that such induced alteration of gut microbiota may at least partially contribute to an increased risk of future metabolic syndrome and gastrointestinal pathology.     

Synthesis and evaluation of in vitro antioxidant capacities of some benzimidazole derivatives

New, except 1d, melatonin analogue benzimidazole derivatives were synthesized and characterized in the present study. The potential role of melatonin as an antioxidant by scavenging and detoxifying ROS raised the possibility that compounds that are analogous to melatonin can also be used for their antioxidant properties. Therefore the antioxidant effects of the newly synthesized compounds were investigated in vitro by means of their inhibitory effect on hydrogen peroxide-induced erythrocyte membrane lipid peroxidation (EMLP) and on various erythrocyte antioxidant enzymes viz. superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PD). The synthesized benzimidazole derivatives showed remarkable antioxidant activity in vitro in the H2O2-induced EMLP system. Furthermore their effects on various antioxidant enzymes are discussed and evaluated from the perspective of structure- activity relationships.     

Investigation of the prevalence of amoebiasis in Izmir province and determination of Entamoeba spp. using PCR and enzyme immunoassay

Amoebiasis is a common and life-threatening disease. The discrimination of the pathogenic Entamoeba histolytica from the non-pathogenic Entamoeba dispar could be done by advanced methods such as enzyme immunoassay (EIA) and PCR. The aim of this study was to investigate the prevalence of amoebiasis in Izmir province, and differentiate the Entamoeba species by PCR and EIA. Stool samples of 2,047 individuals were examined by direct microscopy, formalin ethyl acetate concentration, trichrome staining and culture, and those found to be positive for E. histolytica/dispar by any of these methods were further analyzed by PCR and EIA for species identification. Fifty-nine of 2,047 (2.9%) stool samples were found to be positive for E. histolytica/dispar with microscopy and/or culture. Among these positive samples, E. histolytica was detected in 14 (23.7%) and 5 (8.5%) samples with PCR and antigen-specific ELISA (EIA), respectively. E. dispar was diagnosed in 31 (52.5%) and 52 (88.1%) of 59 samples with species-specific PCR and EIA, respectively. Risk factors related to infection with Entamoeba spp. and other intestinal parasites included living in shanty houses (p < 0.01), a history of recent immigration to Izmir (p < 0.01), having no social security (p < 0.05) and living with a crowded family (p < 0.01). The results demonstrated the significance of amoebiasis as a public health problem among people with low socio-economic status in Izmir province.     

Species distribution, antifungal susceptibility and clonal relatedness of Candida isolates from patients in neonatal and pediatric intensive care units at a medical center in Turkey

The aim of this study was to assess species distribution, antifungal susceptibility and clonal relationships among Candida strains isolated from a group of pediatric/neonatal intensive care (PICU/NICU) patients that had a very high mortality rate (76%). The cases of 21 patients (19 with candidemia, 2 with Candida meningitides) treated over a 1-year period in a Turkish hospital PICU and NICU were retrospectively analyzed. Twenty-eight Candida isolates were detected from blood (20), cerebrospinal fluid (CSF) (2) and other specimens (6). Candida species were identified using the API ID 32C System. Susceptibility testing was done (all 28 isolates) for amphotericin B, fluconazole and itraconazole using the broth microdilution method. Arbitrarily primed polymerase chain reaction (AP-PCR) was used for molecular typing of the 3 most common ones; C. albicans (15), C. parapsilosis (6), and C. pelliculosa (4). Electrophoretic karyotyping (EK) was done to check clonal identity obtained by AP-PCR. Of the 20 blood isolates, 8 (40%) were C. albicans, 12 (60%) were non-albicans Candida, and one of the 2 CSF isolates was C. albicans. The overall species distribution was as follows: 15 C. albicans isolates, 6 C. parapsilosis isolates, 4 C. pelliculosa isolates, 2 C. famata isolates and 1 C tropicalis isolate. Amphotericin B had the best antifungal activity with a MIC90 of 0.125 microg/ml, and the rates of susceptibility to fluconazole and itraconazole were 93% and 82%, respectively. AP-PCR revealed 11 genotypes (4 were identical pairs, 7 were distinct) among the 15 C. albicans isolates, 2 genotypes (5 were classified in the same type) among the 6 C. parapsilosis isolates, and 4 separate genotypes for the 4 C. pelliculosa isolates. Karyotyping results correlated well with the AP-PCR findings. As indicated in the previous research, our results confirmed that non-albicans Candida species have become more frequently causative agents for invasive fungal infections in the ICU. Transmission of C. albicans and C. pelliculosa was relatively low, but transmission of C. parapsilosis was high, suggesting that more effective control and very strict treatment protocols are needed for patients having high mortality and invasive fungal infection in ICU.     

Isoform-specific activation of protein kinase c in irradiated human fibroblasts and their bystander cells

Studies over the last several years have revealed the existence of a biological phenomenon known as "bystander effect", wherein cells that are not exposed to radiation elicit a similar response to that of irradiated cells. Understanding the mechanism(s) underlying the bystander effect is important not only for radiation risk assessment but also for evaluation of protocols for cancer radiotherapy. Evaluation of signaling pathways in bystander cells may provide an insight to understand the molecular mechanisms(s) responsible for this complex phenomenon. With this objective, the time course kinetics of intracellular distribution of protein kinase C (PKC isoforms PKC-betaII, PKC-alpha/beta, PKC-theta) was investigated in total and subcellular (cytosolic and nuclear) fractions of human lung fibroblast (MRC-5) cells. MRC-5 cells were either irradiated or treated with the irradiated conditioned medium collected 1h after 1 or 10 Gy of gamma-irradiation. The radiation dose selected was in the range of therapeutic usage of radiation for the human cancer treatment. Unexpectedly, bystander cells showed higher activation of protein kinase C isoforms as compared to irradiated and sham-treated control cells. Protein kinase C isoforms were more enriched in the nuclear fraction than the cytosolic fraction proteins. Induction of PKC isoforms in bystander cells are due to post-translational modifications as shown by the non-phosphorylated protein kinase C level in both irradiated and bystander cells did not differ from the sham-treated control cells. The specific activation of protein kinase C isoforms in bystander cells as demonstrated for the first time in this study may help to identify the effect of therapeutically used radiation exposure for the tumor destructions along with its implications for adjacent non-irradiated cells and organs.