The role of antioxidants in sperm freezing: a review

Cryopreservation of spermatozoa is becoming more important because of new clinical requirements and current clinical practice. Despite the success of sperm cryopreservation this routinely used procedure induces serious detrimental changes in sperm function. Some researchers believe that cryopreservation is associated with DNA fragmentation and DNA single strand breaks in sperm. Mechanisms of cryodamage to human spermatozoa are thought to be multifactorial including: cold shock, osmotic stress, intracellular ice crystal formation, oxidative stress, and combinations of these conditions. Additives showing antioxidative properties reported to reduce the impact of ROS-induced and cold shock damages. Many studies exist as regards the effects of antioxidants on the cryopreservation aimed at improving the quality of post-thaw semen. Hence, this review will clarify results of recent applications of various antioxidants used in numerous research efforts to improve cryopreservation of spermatozoa. This review is to increase the understanding of the roles of these antioxidants concerning mechanisms which enhance resistance to cryodamage of spermatozoa.     

Plasmonics Optoelectronics Nanobiosensors for Detection of Alzheimer’s Disease Biomarker via Amyloid-Beta (Aβ) in Near-Infrared

The development of diagnostic factors for such neurodegenerative disorders as Alzheimer’s disease is hindered by several limitations that are often witnessed in the early detection of biomarkers in cerebrospinal fluid (CSF) and bio-fluids in clinical contexts. Therefore, here, we suggest a highly sensitive plasmonics nanobiosensor for detection of Alzheimer on one nanodevice through the excitation of surface plasmon resonance (SPR) depending on graphene chemical potential, called a nanobiosensor. This plasmonic nanobiosensor consists of only graphene metasurfaces and samples but does not need extra approaches for the exact analysis of the sample refractive index. Under FDTD simulation, we analyze the sensitivity of 3900 l/RIU for amyloid-beta (Aβ) and figure of merit of 138. This is the first high-performance plasmonics nanobiosensor to monitoring of Alzheimer samples which can be used to detect Alzheimer easily in the future.

     

MicroRNA-203 reinforces stemness properties in melanoma and augments tumorigenesis in vivo

One of the challenges encountered in microRNA (miRNA) studies is to observe their dual role in different conditions and cells. This leads to a tougher prediction of their behavior as gene expression regulators. miR-203 has been identified to play a negative role in the progression of malignant melanoma; however, it has been reported, with dual effect, as both an oncomiR and tumor suppressor miRNA in some malignancies, such as breast cancer, meanwhile, the role of miR-203 in melanoma stem cells or even metastatic cells is unclear. In the present study, after observation of upregulation of miR-203 in melanoma patient's serum and also melanospheres as cancer stem cells model, we examined its overexpression on the stemness potential and migration ability of melanoma cells. Our data demonstrated that the increased miR-203 level was significantly associated with significant increase in the ability of proliferation, colony and spheres formation, migration, and tumorigenesis in A375 and NA8 cells. All of these changes were associated with enhancement of BRAF, several epithelial to mesenchymal transition factors, and stemness genes. In conclusion, our results clearly determined that miR-203 could be down-regulateddownregulated in melanoma tissues but be overexpressed in melanoma stem cells. It has an important role as oncomiR and promote repopulation, tumorigenicity, self-renewal, and migration. Therefore, we suggested overexpression of miR-203 as biomarker for early detection of metastasis. However, more studies are needed to validate our data.     

Theoretical study of the complementarity in halogen–bonded complexes involving nitrogen and halogen as negative sites

The conformations of trialkylphosphates (alkyl = propyl, butyl, pentyl and hexyl) in various diluents were studied by molecular dynamics simulations. The population density of various conformers of trialkylphosphate in different diluents such as water and n-dodecane was determined. The Helmholtz energy change accompanied by the transition between various conformations was computed. The aggregation behavior of tributylphosphate in water and water-dodecane medium was studied.     

Characterization of halogen···halogen interactions in crystalline dihalomethane compounds (CH2Cl2, CH2Br2 and CH2I2): a theoretical study

To improve understanding of the unimolecular decomposition mechanism of 1,2,4-butanetriol trinitrate (BTTN) in the gas phase, density functional theory calculations were performed to determine various decomposition pathways at the B3LYP/6-311G** level. Two main mechanisms for the unimolecular decomposition of BTTN were found. In the first, homolysis of one of the O–NO₂ bonds occurs to form ?NO₂ and CH₂ONO₂CHONO₂CH₂CH₂O?, which subsequently decomposes to form CH₃CHO + ?CHO + 3NO₂ + HCHO. In the second, successive HONO elimination reactions yield three HONO and OHCCH₂CHONO₂CH₂ONO₂ fragments, which subsequently decompose to form CH₃CHO + 2CO + 3HONO. We also found that the first pathway has a slightly lower activation energy than the second. The results show that the pathway involving O–NO₂ cleavage is slightly more energetically favorable than that involving HONO elimination.     

Highly Sensitive Surface Plasmon Resonance Biosensors Utilizing Prism-Waveguide Configuration for Detection of Alzheimer Disease Biomarker

Plasmonics - Alzheimer’s disease (AD) is a disease in cognitive regions in the human brain. Also the detection of AD in the early stage is too important. In this regard, a surface plasmon...