Characterization of the interaction between human serum albumin and diazinon via spectroscopic and molecular docking methods.

Human serum albumin (HSA) is a soluble blood protein which binds to small molecules (such as drugs and toxins) and transfers them within the blood circulation. In this research, the interaction of diazinon, as a toxic organophosphate, with HSA was investigated. Various biophysical methods such as fluorescence, ultraviolet-visible (UV-vis), Fourier transform infrared spectroscopy, and molecular docking were utilized to characterize the binding properties of diazinon to HSA under physiological-like condition. The UV-vis spectroscopy showed that the absorption increased and the fluorescence intensity of HSA decreased regularly with regard to the gradual increases of the concentrations of diazinon. Due to the binding constant of ( ka = 3.367 × 10+4 M-1), the α-helix structure for the first day and 35 days of incubation were obtained 66.09-55.4% and 59.99-46.48%, respectively, and their amounts in other secondary structures (ß-sheet, ß-anti, and random (r) coils) were increased. The molecular docking revealed a good binding site in HSA (Trp-214) for diazinon which was related to the considerable alterations in HSA secondary and tertiary structures. There is a close relationship between the secondary structure of protein and its biological activity and after 35 days of incubation, the high toxic concentrations of diazinon can make HSA to be partially unfolded and lose its structure.

Normalized impact factor (NIF): an adjusted method for calculating the citation rate of biomedical journals.

The interests in journal impact factor (JIF) in scientific communities have grown over the last decades. The JIFs are used to evaluate journals quality and the papers published therein. JIF is a discipline specific measure and the comparison between the JIF dedicated to different disciplines is inadequate, unless a normalization process is performed. In this study, normalized impact factor (NIF) was introduced as a relatively simple method enabling the JIFs to be used when evaluating the quality of journals and research works in different disciplines. The NIF index was established based on the multiplication of JIF by a constant factor. The constants were calculated for all 54 disciplines of biomedical field during 2005, 2006, 2007, 2008 and 2009 years. Also, ranking of 393 journals in different biomedical disciplines according to the NIF and JIF were compared to illustrate how the NIF index can be used for the evaluation of publications in different disciplines. The findings prove that the use of the NIF enhances the equality in assessing the quality of research works produced by researchers who work in different disciplines.

Propensity of amino acids in loop regions connecting beta-strands.

The fact that loops assume important roles in molecular functions and biological recognition is well known. In this study the Propensity and the Relative entropy of amino-acids in loop structures connecting beta-strands are calculated. Results showed that Asn is the most frequently occurring amino-acid in loop regions connecting beta-strands, followed by Gly, Asp, Ser, and Thr. Results presented here can serve for modeling loop structures connecting beta-strands in proteins.

Inhibition and recovery of GM-CSF production in the lung after hyperthermia.

The purpose of this work was to study the response that is invoked by hyperthermia in the production of Granulocyte-Macrophage colony-stimulating factor (GM-CSF) by the lung. Rats were heated regionally at chest area by a RF generator operating at 27.397 MHz for 1 h at various temperatures and then allowed to recover or repair in various periods of time after heat application. Lung tissue from these animals was then removed and cultured for the production of GM-CSF. GM-CSF was assayed by the production of colonies in the semi-solid agar cultures of bone marrow cells. Immediately after heat treatment hyperthermia had no significant effect on the production of GM-CSF by the lung. A delayed effect was observed about 3.5 h after heat treatment. This effect consisted of a temperature dependent decrease in GM-CSF production. The damage was recoverable and required 1-50 days of post heat treatment time for animals to reach normal level of GM-CSF production. The results suggest that in-vivo application of hyperthermia invokes temporary reduction in GM-CSF production by the lung, which has not been reported previously.

Behaviour of heat-treated bone marrow cells in long-term bone marrow cultures.

The effect of prior heat treatment on the ability of bone marrow cells to form long-term bone marrow culture has been studied. Bone marrow cells were heated for various times in the temperature range of 39-43 degrees C and then cultured in the modified Dexter type suspension culture. At weekly intervals, the behaviour of the cultures in terms of stroma formation and confluency, cellular viability, and myelopoiesis were evaluated. The results show that there was a dose-dependent decrease in the number of viable cells in the non-adherent fraction of the cultures. Cytological analysis of these cells showed a strong shift towards macrophage population in the successive weeks of the cultures and also as a function of heat dose delivered to these cultures. The stroma formation was delayed or inhibited as a function of the heat dose. The number of granulocyte-macrophage colony forming cells (CFU-GM) in both adherent and non-adherent fraction of the cultures were decreased substantially after hyperthermia treatment. At 41 degrees C and higher temperatures, the CFU-GM were severely diminished in both fractions. The dose response experiments showed that the decrease in the number of CFU-GM was dependent on the heat dose. The results suggest that CFU-GM is an extremely sensitive target in the hyperthermia treatment of bone marrow cells and heat-treated bone marrow cells lose their ability to maintain long-term cultures.

Effects of hyperthermia and granulocyte-macrophage colony-stimulating factor on the differentiation of human leukemic cell line U937.

We have studied the effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) and hyperthermia individually and in combination on the cell growth and differentiation of human monoblastic leukemia cell line U937. Several criteria were used to evaluate the differentiation of these cells, including the reduction in the plating efficiency and cell growth, the ability to phagocytize latex particles, the reduction of nitro blue tetrazolium (NBT), and development of surface antigenic markers. Hyperthermia alone was able to inhibit cell proliferation, reduce cell viability, and induce differentiation. In the range of 41-43 degrees C, the major effect of hyperthermia was cell differentiation induction as judged by above criteria. On average, hyperthermia induced differentiation in 32% of cells. GM-CSF was able to induce differentiation in 37% of U937 cells as judged by similar criteria. The combined treatment with GM-CSF and hyperthermia resulted in the differentiation of 60% of U937 cells. The extent of differentiation obtained is comparable or better than other combinatorial treatments using various cytokines or cytokines and chemical reagents reported before.

Hematopoiesis in the presence of macrophages in long-term bone marrow cultures.

We have studied the role of macrophages as stromal elements in long-term cultures of murine bone marrow cells. Normal ectopic macrophages were collected from the lung and co-cultured in various ratios with bone marrow cells in Dexter suspension cultures. At weekly intervals, various parameters of the cultures were evaluated and compared with controls. Increased numbers of macrophages in the bone marrow caused a delay in the formation of the confluent stroma, with distinct differences in the pattern of hematopoietic foci in the stroma. Cytologic analysis of nucleated cells in the nonadhering fraction showed that the monocytic macrophages were the eventual line of differentiation in all cultures; however, this phenomenon was accelerated in cultures containing various fractions of macrophages. There was a dose-dependent reduction in the number of myeloid progenitors in the nonadhering and adhering fractions of macrophage-enriched cultures with respect to controls. This effect was mediated through both humoral factors released in the culture and direct interaction between macrophages and bone marrow cells. The result indicate that elevation of the number of macrophages in the bone marrow could result in an impaired process of hematopoiesis.

Biocompatibility evaluation of laser-induced AAm and HEMA grafted EPR. Part 1: In-vitro study.

Samples based on ethylene-propylene rubber (EPR) have been surface grafted with acrylamide (AAm) and 2-hydroxyethyl methacrylate (HEMA) using CO2-pulsed laser as a stimulation source. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA) and attenuated total reflectance infrared (ATR-IR) spectra were performed on the modified samples. These techniques revealed the formation of grafted poly(AAm) and poly(HEMA) on the surface of EPR. The surface grafted poly(AAm) and poly(HEMA) were found to have a fractal type of morphology. EDXA showed insignificant grafted AAm and HEMA in regions where fractals were absent. Fractal patterned surfaces provide hydrophilic and hydrophobic sites, making EPR suitable as a biomaterial. In-vitro adhesion and spreading of alveolar macrophages (AMs) cultured on the surface of modified samples have been evaluated by hemocytometry and SEM, respectively, and compared with unmodified controls. Relationships between AM adhesion and their spreading, with surface morphology, graft level and water compatibility are also discussed. Generally, more AMs attach onto unmodified surfaces with a greater degree of spreading, than on the modified EPR. Samples grafted between 0.7 mg/cm2 and 1 mg/cm2 showed fairly low AM density compared with both unmodified EPR and lightly modified samples (less than 0.2 mg/cm2). AMs cultured on the unmodified EPR were larger and displayed pronounced ruffling of the plasma membrane, an increased capacity for adherence and spreading on the surface, and an increased number of extensive filopodia. Moreover, AMs attached onto the surface of modified samples appeared rounded, with minimal cytoplasmic spreading and ruffling.

Inhibitory role of alveolar macrophages in colony-stimulating factor production by the lung tissue from bacillus Calmette-Guérin-treated animals.

Production of colony-stimulating factors (CSF) by lung tissue from rats injected by bacillus Calmette-Guérin (BCG) and the role of alveolar macrophages (AM) in this process was studied. Injection of BCG at 10, 100, or 1,000 mg/kg changed the CSF production by the lung in a time-dependent manner. Maximum stimulation was observed at 10 mg/kg and 3 days of interval between BCG injection and animal sacrifice. Longer periods or higher concentrations had no effect or actually depressed CSF production. BCG injection also changed the number of AM in a time- and dose-dependent manner. When AM from BCG-treated animals were lavaged out and the AM-depleted lung tissues were cultured, an increase in CSF production with respect to controls was observed at 10 mg/kg of BCG. On the other hand, in control animals removal of AM had no effect on CSF production by the lung. The results suggest that BCG treatment alters the number of AM and CSF production by the lung. AM, in BCG-injected animals, inhibit CSF production by the lung tissue while in non-injected animals they do not play any role in this process.

Effects of hyperthermia on the colony-stimulating factor production by the lung.

Hyperthermic treatment of the murine lung in the range of 40-46 degrees C inhibited the production of colony-stimulating factors by the lung in vitro. This inhibition was dose dependent. Thermodynamic analysis was used to determine the activation energies. The Arrhenius plot contained a transition at 43 degrees C. At temperatures below and above the transition temperature, the activation energies were 40.49 and 197 kcal/mole, respectively. Below the transition temperature, the effect of hyperthermia was characterized by a delayed response represented by the broad initial shoulder of the hyperthermic dose-response curves. To investigate the mechanism of hyperthermia-induced reduction of the colony-stimulating factor production, the effect of hyperthermia on the protein synthesis by the lung was also studied. The results indicated an immediate response to hyperthermia, characterized by the absence of the initial shoulder and the high slope of the hyperthermic dose response curves. The corresponding Arrhenius plot did not have any transition point. The single activation energy calculated was 97.25 kcal/mole. It is concluded that the hyperthermic depression of the colony-stimulating factor production by the lung cannot be explained solely on the basis of the effects of hyperthermia on the protein synthesis.

The effect of indomethacin on colony-stimulating-factor production by the lung.

In this study, indomethacin was used to investigate the production of colony-stimulating-factor by the lung tissue. Addition of various concentrations of indomethacin (10(-5)-1 mg/ml) to the lung culture showed that it enhances CSF production in a dose dependent manner. The number of colonies reached a maximum at 1 microgram/ml and gradually diminished at higher concentrations. Addition of exogenous E-series prostaglandins alone had no effect on the CSF activity of normal lung. However, in the presence of indomethacin, E-series prostaglandins reversed the enhancing effect produced by indomethacin. On the other hand, cAMP or its dibutyryl derivative also increased CSF production. Removal of alveolar macrophages from the lung by lavaging had no effect on the CSF production by the lung but reduced the enhancing effect of indomethacin by 50%. The results suggest that indomethacin stimulates CSF production and that this process is partially regulated by prostaglandins and cAMP.