328 research outputs found
Identification and density of ichthyoplankton in Laft Creeks (Hormuzgan province)
During a series of Ichthyoplankton survey from May 1998 to April 1999 Ichthyoplankton samples were collected at 12 stations in Laft creeks by 500 micron bongonet with oblique towing from bottom to water surface. Twenty-two families Ichthyoplanktons were identified (and two unidentified) during 12 months. Clupeiidae (31, 32%), gobiidae (26, 71%), scianidae (16, 55%), leiognathidae (11, 9%) were common and dominant families in all sampling stations. The creeks was divided in two branches: In east branch gobiidae (44.75%), clupeiidae (17.42%), scianida (13.5%) were more abundant than other families and in west branch clupeiidae (34.22%), gobiidae (23.77%), scianidae (16.34%) showed leiognathidae (13.26%) more abundance than other families, too. Some families e.g hemiramphidae, engrauilidae, blenidae, bothidae only occur in west branch, pleuronectidae family only occur in west branch. The highest density was found in winter season
More than one dynamic crossover in protein hydration water
Studies of liquid water in its supercooled region have led to many insights
into the structure and behavior of water. While bulk water freezes at its
homogeneous nucleation temperature of approximately 235 K, for protein
hydration water, the binding of water molecules to the protein avoids
crystallization. Here we study the dynamics of the hydrogen bond (HB) network
of a percolating layer of water molecules, comparing measurements of a hydrated
globular protein with the results of a coarse-grained model that has been shown
to successfully reproduce the properties of hydration water. With dielectric
spectroscopy we measure the temperature dependence of the relaxation time of
protons charge fluctuations. These fluctuations are associated to the dynamics
of the HB network of water molecules adsorbed on the protein surface. With
Monte Carlo (MC) simulations and mean--field (MF) calculations we study the
dynamics and thermodynamics of the model. In both experimental and model
analyses we find two dynamic crossovers: (i) one at about 252 K, and (ii) one
at about 181 K. The agreement of the experiments with the model allows us to
relate the two crossovers to the presence of two specific heat maxima at
ambient pressure. The first is due to fluctuations in the HB formation, and the
second, at lower temperature, is due to the cooperative reordering of the HB
network
An extended laser flash technique for thermal diffusivity measurement of high-temperature materials
Knowledge of thermal diffusivity data for high-temperature materials (solids and liquids) is very important in analyzing a number of processes, among them solidification, crystal growth, and welding. However, reliable thermal diffusivity versus temperature data, particularly those for high-temperature liquids, are still far from complete. The main measurement difficulties are due to the presence of convection and the requirement for a container. Fortunately, the availability of levitation techniques has made it possible to solve the containment problem. Based on the feasibility of the levitation technology, a new laser flash technique which is applicable to both levitated liquid and solid samples is being developed. At this point, the analysis for solid samples is near completion and highlights of the technique are presented here. The levitated solid sample which is assumed to be a sphere is subjected to a very short burst of high power radiant energy. The temperature of the irradiated surface area is elevated and a transient heat transfer process takes place within the sample. This containerless process is a two-dimensional unsteady heat conduction problem. Due to the nonlinearity of the radiative plus convective boundary condition, an analytic solution cannot be obtained. Two options are available at this point. Firstly, the radiation boundary condition can be linearized, which then accommodates a closed-form analytic solution. Comparison of the analytic curves for the temperature rise at different points to the experimentally-measured values will then provide the thermal diffusivity values. Secondly, one may set up an inverse conduction problem whereby experimentally obtained surface temperature history is used as the boundary conditions. The thermal diffusivity can then be elevated by minimizing the difference between the real heat flux boundary condition (radiation plus convection) and the measurements. Status of an experimental study directed at measuring the thermal diffusivity of high-temperature solid samples of pure Nickel and Inconel 718 superalloys are presented. Preliminary measurements showing surface temperature histories are discussed
Study of the effect of bacterial lipopolysaccharide on the structure and dynamics on mouse tubulin polymerization
Background and aims: In recent decades, there has been much research on the microtubule dynamics as well as on factors affecting it. According to different studies, lipopolysaccharide (LPS) is thought to play an indirect role in neurodegenerative diseases through enzymatic pathways which hyperphosphorylate Tau protein and dissociate it from microtubules. In the present study, it was aimed to assess the direct effect of LPS on the structure and dynamics of tubulin polymerization in vitro.
Methods: In this study, mouse tubulins were purified through two cycles of temperature-dependent polymerization-depolymerization. Cellulose-phosphate chromatography was used to further purify tubulins. SDS-PAGE was used to analyze the purity of the tubulins. Circular dichroism (CD), intrinsic fluorescence and turbidity assays were used to assess the changes in secondary and tertiary structures, and the dynamics of tubulin polymerization in the presence of different concentrations of LPS (5pM, 5nM, 50nM, 0.5µM and 5µM), respectively.
Results: SDS-PAGE analysis confirmed the purity of tubulins. The intrinsic fluorescence analysis and CD assay revealed the changes in the secondary and tertiary structures of tubulins in the presence of LPS. The results of turbidity assay indicated that LPS could reduce the polymerization of tubulins.
Conclusion: Our results indicate that LPS is able to change the secondary and tertiary structures of tubulin and decreases tubulin polymerization. According to our results, lipopolysaccharide in addition to an indirect effect on the microtubules stability, as well as by decreases in tubulin polymerization could result in neurodegenerative diseases specially Alzheimer's diseases
Additive manufacturing of bioactive glass biomaterials
Tissue engineering (TE) and regenerative medicine have held great promises for the repair and regeneration of damaged tissues and organs. Additive manufacturing has recently appeared as a versatile technology in TE strategies that enables the production of objects through layered printing. By applying 3D printing and bioprinting, it is now possible to make tissue-engineered constructs according to desired thickness, shape, and size that resemble the native structure of lost tissues. Up to now, several organic and inorganic materials were used as raw materials for 3D printing; bioactive glasses (BGs) are among the most hopeful substances regarding their excellent properties (e.g., bioactivity and biocompatibility). In addition, the reported studies have confirmed that BG-reinforced constructs can improve osteogenic, angiogenic, and antibacterial activities. This review aims to provide an up-to-date report on the development of BG-containing raw biomaterials that are currently being employed for the fabrication of 3D printed scaffolds used in tissue regeneration applications with a focus on their advantages and remaining challenges
Association of vitamin D level and vitamin D deficiency with risk of preeclampsia: A systematic review and updated meta-analysis
Objectives: Because of the immune modulatory effects of vitamin D3 in preeclampsia, we intend to have a systematic review and meta-analysis on association of both 25-hydroxy vitamin D (25-OHD) level (parametric approach) and 25-OHD deficiency (non-parametric approach) with preeclampsia. As well, for the parametric part, we used receiver operating characteristic (ROC) curve model. Materials and methods: We used Web of Science, PubMed and Science Direct data bases through searching in titles. Google Scholar search engine was used in order to find missing papers. Finally 23 studies were imported. Both random and fixed models were reported. Results: Based on the forest plot, lower levels of 25-OHD were significantly associated with risk of preeclampsia (fixed and random P < 0.001). Based on the forest plot, vitamin D deficiency (25-OHD < 20 ng/ml) was significantly associated with risk of preeclampsia (fixed P < 0.0001; random P = 0.0029; fixed OR = 1.33; random OR = 1.54). Based on ROC curve results, we found 2 cutoffs of 10.60 and 20.05 ng/ml. Conclusion: Women with vitamin D deficiency at cutoff 20 ng/ml are more at risk of preeclampsia. This association can be specific up to 90 at 10.60 ng/ml cutoff. Treatment of vitamin D deficiency is necessary before pregnancy. © 201
Association of vitamin D level and vitamin D deficiency with risk of preeclampsia: A systematic review and updated meta-analysis
Objectives: Because of the immune modulatory effects of vitamin D3 in preeclampsia, we intend to have a systematic review and meta-analysis on association of both 25-hydroxy vitamin D (25-OHD) level (parametric approach) and 25-OHD deficiency (non-parametric approach) with preeclampsia. As well, for the parametric part, we used receiver operating characteristic (ROC) curve model. Materials and methods: We used Web of Science, PubMed and Science Direct data bases through searching in titles. Google Scholar search engine was used in order to find missing papers. Finally 23 studies were imported. Both random and fixed models were reported. Results: Based on the forest plot, lower levels of 25-OHD were significantly associated with risk of preeclampsia (fixed and random P < 0.001). Based on the forest plot, vitamin D deficiency (25-OHD < 20 ng/ml) was significantly associated with risk of preeclampsia (fixed P < 0.0001; random P = 0.0029; fixed OR = 1.33; random OR = 1.54). Based on ROC curve results, we found 2 cutoffs of 10.60 and 20.05 ng/ml. Conclusion: Women with vitamin D deficiency at cutoff 20 ng/ml are more at risk of preeclampsia. This association can be specific up to 90 at 10.60 ng/ml cutoff. Treatment of vitamin D deficiency is necessary before pregnancy. © 201
Molecular detection and prevalence of chlamydophila psittaci in the blood, liver and muscle tissue of urban pigeons (columba livia domestica) in iran
LncRNA RP11-19E11 is an E2F1 target required for proliferation and survival of basal breast cancer
Long non-coding RNAs (lncRNAs) play key roles in the regulation of breast cancer initiation and progression. LncRNAs are differentially expressed in breast cancer subtypes. Basal-like breast cancers are generally poorly differentiated tumors, are enriched in embryonic stem cell signatures, lack expression of estrogen receptor, progesterone receptor, and HER2 (triple-negative breast cancer), and show activation of proliferation-associated factors. We hypothesized that lncRNAs are key regulators of basal breast cancers. Using The Cancer Genome Atlas, we identified lncRNAs that are overexpressed in basal tumors compared to other breast cancer subtypes and expressed in at least 10% of patients. Remarkably, we identified lncRNAs whose expression correlated with patient prognosis. We then evaluated the function of a subset of lncRNA candidates in the oncogenic process in vitro. Here, we report the identification and characterization of the chromatin-associated lncRNA, RP11-19E11.1, which is upregulated in 40% of basal primary breast cancers. Gene set enrichment analysis in primary tumors and in cell lines uncovered a correlation between RP11-19E11.1 expression level and the E2F oncogenic pathway. We show that this lncRNA is chromatin-associated and an E2F1 target, and its expression is necessary for cancer cell proliferation and survival. Finally, we used lncRNA expression levels as a tool for drug discovery in vitro, identifying protein kinase C (PKC) as a potential therapeutic target for a subset of basal-like breast cancers. Our findings suggest that lncRNA overexpression is clinically relevant. Understanding deregulated lncRNA expression in basal-like breast cancer may lead to potential prognostic and therapeutic applications
- …