Intravascular detection of inflamed atherosclerotic plaques using a fluorescent photosensitizer targeted to the scavenger receptor.

Inflammation plays an important role in the pathophysiology of atherosclerotic disease. We have previously shown that the targeted photosensitizer chlorin (e(6)) conjugated with maleylated albumin (MA-ce6) is taken up by macrophages via the scavenger receptor with high selectivity. In a rabbit model of inflamed plaque in New Zealand white rabbits via balloon injury of the aorto-iliac arteries and high cholesterol diet we showed that the targeted conjugate showed specificity towards plaques compared to free ce6. We now show that an intravascular fiber-based spectrofluorimeter advanced along the -iliac vessel through blood detects 24-fold higher fluorescence in atherosclerotic vessels compared to control rabbits (p < 0.001 ANOVA). Within the same animals, signal derived from the injured iliac artery was 16-fold higher than the contralateral uninjured iliac (p < 0.001). Arteries were removed and selective accumulation of MA-ce6 in plaques was confirmed using: (1) surface spectrofluorimetry, (2) fluorescence extraction of ce6 from aortic segments, and (3) confocal microscopy. Immunohistochemical analysis of the specimens showed a significant correlation between MA-ce6 uptake and RAM-11 macrophage staining (R = 0.83, p < 0.001) and an inverse correlation between MA-ce6 uptake and smooth muscle cell staining (R = -0.74, p < 0.001). MA-ce6 may function as a molecular imaging agent to detect and/or photodynamically treat inflamed plaques.     

Polygalacturonase causes lygus-like damage on plants: cloning and identification of western tarnished plant bug (Lygus hesperus) polygalacturonases secreted during feeding

Polygalacturonase (PG), an enzyme that degrades pectin within the plant tissue cell wall, has been postulated as the chemical cause of damage to plants by the mirid Lygus hesperus. Micro-injection of two pure recombinant Aspergillus niger PG II protein forms, the wild type enzymically active and the mutant inactive one, into alfalfa (Medicago sativa L.) florets, demonstrates that the enzymatic activity rather than the PG protein structure per se elicits damage symptoms. A PG gene family has been described for the tarnished plant bug, L. lineolaris. Here we report cloning members of the L. hesperus PG gene family, Lhpg2, obtained with L. lineolaris PG-specific primers and a novel Lhpg4, amplified with degenerate primers that were designed based, in part on the N-terminal sequence from an active, partially purified L. hesperus salivary gland PG protein. Proteomic analyses revealed that the salivary gland PGs encoded by Lhpg2 and Lhpg4 are detected in a diet into which L. hesperus has extruded its saliva when feeding. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: Henryk Czosnek     

Interaction of diazinon with DNA and the protective role of selenium in DNA damage

The interaction of native calf thymus DNA with Diazinon, an organophophorus insecticide, in HEPES buffer at neutral pH, was monitored by UV absorption spectrophotometry, circular dichroism (CD), electrochemical technique, and fluorescence spectroscopy. UV spectra showed hyperchromicity and blue shift with the increase of Diazinon concentration. Fluorescence spectroscopy results indicated that the probable quenching mechanism of DNA-ethidium bromide (EB) fluorescence by Diazinon is a dynamic quenching procedure, because the Stern-Volmer quenching constant (K(SV)) increased with the temperature rising. Unchanging of the CD signal around 280 nm with increasing ratio of Diazinon to DNA is an important evidence for non-intercalative-binding mode of Diazinon with DNA. Stoichiometry measurement of the DNA-nDiazinon indicated that a stable 1:2 complex of DNA-Diazinon was formed under the selected conditions. The electrochemical study of the Diazinon-DNA interaction was carried out by incubation of DNA with Diazinon in the presence of varying amounts of selenium (Se). This technique revealed that Se is able to diminish the DNA damage effect of Diazinon.     

Blood Levels of Lead, Cadmium, and Mercury in Residents of Tehran

Monitoring of toxic trace elements for human blood has been of interest to researchers in the fields of environmental chemistry and medical science. The amount of blood toxic elements can reflect the disease state of the person or the environment where that person resides or works. Chronic, low-level exposure to toxic metals such as lead (Pb), cadmium (Cd), and mercury (Hg) is an increasing global problem. This study focuses on obtaining the usual value of Pb, Cd, and Hg in normal human blood. These elements were determined in 61 male and 40 female volunteers resident in Tehran (Iran). The subjects were non-drug abusers and aged 6-62 years old. Procedures were developed for the collection, storage, and preanalytical treatment of samples. The lead and cadmium were determined by graphite furnace atomic absorption spectrometry, and mercury was measured by cold vapor atomic absorption spectrometry technique. The blood levels of Pb, Cd, and Hg in normal volunteers living in Tehran were 123.75 +/- 56.42, 1.82 +/- 0.67, and 8.48 +/- 4.42 microg/L. There was no significant gender-related difference in blood Cd and Hg concentrations (p < 0.06 and p < 0.41). However, the results indicated significantly higher content of Pb in blood of males compared to females (138.11 +/- 65.43 and 101.84 +/- 51.38 microg/L, respectively, p < 0.05).     

Observation of Optical Bistability in a Polaritonic Material Doped with Nanoparticles

We study the optical bistability and multistability in a defect structure doped with polaritonic materials and three-level nanoparticles. It is realized that the threshold of optical bistability can be manipulated by some controllable parameters such as Rabi frequency, line width of upper level, and thickness of defect structure. Due to dense doping of three-level nanoparticles, the dipole-dipole interactions (DDI) between nanoparticles become important. Therefore, the DDI has been considered as an interesting mechanism for transition from optical bistability to multistability. The line width effect of upper level and thickness of defect structure on threshold of optical multistability has also been investigated. We hope that our proposed model may be useful for developing the future all-optical devices in nanoscales.

     

The impact of including tRNA content on the optimality of the genetic code

Statistical and biochemical studies have revealed nonrandom patterns in codon assignments. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslational errors and point mutations, since it is known that, when an amino acid is converted to another due to error, the biochemical properties of the resulted amino acid are usually very similar to those of the original one. In this study, we have taken into consideration both relative frequencies of amino acids and relative gene copy frequencies of tRNAs in genomic sequences in order to introduce a fitness function which models the mistranslational probabilities more accurately in modern organisms. The relative gene copy frequencies of tRNAs are used as estimates of the tRNA content. We also altered the rule previously used for the calculation of the probabilities of single base mutation occurrences. Our model signifies higher optimality of the genetic code towards load minimization and suggests the presence of a coevolution of tRNA frequency and the genetic code.     

Suppression of death receptor signaling in cerebellar Purkinje neurons protects neighboring granule neurons from apoptosis via an insulin-like growth factor I-dependent mechanism

Neuronal apoptosis contributes to the progression of neurodegenerative disease. Primary cerebellar granule neurons are an established in vitro model for investigating neuronal death. After removal of serum and depolarizing potassium, granule neurons undergo apoptosis via a mechanism that requires intrinsic (mitochondrial) death signals; however, the role of extrinsic (death receptor-mediated) signals is presently unclear. Here, we investigate involvement of death receptor signaling in granule neuron apoptosis by expressing adenoviral, AU1-tagged, dominant-negative Fas-associated death domain (Ad-AU1-deltaFADD). Ad-AU1-deltaFADD decreased apoptosis of granule neurons from 65 +/- 5 to 27 +/- 2% (n = 7, p < 0.01). Unexpectedly, immunocytochemical staining for AU1 revealed that <5% of granule neurons expressed deltaFADD. In contrast, deltaFADD was expressed in >95% of calbindin-positive Purkinje neurons ( approximately 2% of the cerebellar culture). Granule neurons in proximity to deltaFADD-expressing Purkinje cells demonstrated markedly increased survival. Both granule and Purkinje neurons expressed insulin-like growth factor-I (IGF-I) receptors, and deltaFADD-mediated survival of granule neurons was inhibited by an IGF-I receptor blocking antibody. These results demonstrate that the selective suppression of death receptor signaling in Purkinje neurons is sufficient to rescue neighboring granule neurons that depend on Purkinje cell-derived IGF-I. Thus, the extrinsic death pathway has a profound but indirect effect on the survival of cerebellar granule neurons.     

Retinoic acid metabolism inhibition by 3-azolylmethyl-1H-indoles and 2, 3 or 5-(alpha-azolylbenzyl)-1H-indoles

Among a library of 70 azoles, 8 indole derivatives substituted in the 2-, 3- or 5- position with an azolylmethyl or alpha-azolylbenzyl chain were evaluated for retinoic acid (RA) metabolism inhibitory activity. The most active inhibitors identified in this study were 5-bromo-1-ethyl-3-methyl-2-[(phenyl)(1H-1,2,4-triazol-1-yl)methyl]-1H-indole (3) (68.9% inhibition) and 5-bromo-1-ethyl-2-[(4-fluorophenyl) (1H-1,2,4-triazol-1-yl)methyl]-3-methyl-1H-indole (6) (60.4% inhibition). At the same concentration (100 microM) ketoconazole exerted similar inhibitory effect (70% inhibition).     

On the optimality of the genetic code, with the consideration of termination codons

The existence of nonrandom patterns in codon assignments is supported by many statistical and biochemical studies. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslation errors and point mutations. For example, it is known that when an error induces the conversion of an amino acid to another, the biochemical properties of the resulting amino acid are usually very similar to that of the original. Prior studies include many attempts at quantitative estimation of the fraction of randomly generated codes which, based upon load minimization, score higher than the canonical genetic code. In this study, we took into consideration both the relative frequencies of amino acids and nonsense mistranslations, factors which had been previously ignored. Incorporation of these parameters, resulted in a fitness function (phi) which rendered the canonical genetic code to be highly optimized with respect to load minimization. Considering termination codons, we applied a biosynthetic version of the coevolution theory, however, with low significance. We employed a revised cost for the precursor-product pairs of amino acids and showed that the significance of this approach depends on the cost measure matrix used by the researcher. Thus, we have compared the two prominent matrices, point accepted mutations 74-100 (PAM(74-100)) and mutation matrix in our study.     

A high-sensitivity electrochemical immunosensor based on mobile crystalline material-41-polyvinyl alcohol nanocomposite and colloidal gold nanoparticles

A novel competitive immunosensor was developed as a model system using anti-human serum albumin (HSA)-conjugated gold nanoparticles (AuNPs) as an electrochemical label and mobile crystalline material-41 (MCM-41)–polyvinyl alcohol (PVA) mesoporous nanocomposite as an immobilization platform. However, no attempt has yet been made to use the MCM-41 as the supporting electrolyte for the electrosynthesis of nonconducting polymer nanocomposite. This hybrid membrane was evaluated extensively by using field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) to determine its physicochemical and electrochemical properties in immunosensor application. FESEM revealed an appropriate and stable attachment between HSA and MCM-41 and also a dense layer deposition of MCM-41–HSA–PVA film onto the electrode surfaces. DPV was developed for quantitative determination of antigen in biological samples. A decrease in DPV responses was observed with increasing concentrations of HSA in standard and real samples. In optimal conditions, this immunosensor based on MCM-41–PVA nanocomposite film could detect HSA in a high linear range (0.5–200 μg ml^?1) with a low detection limit of 1 ng ml^?1. The proposed method showed acceptable reproducibility, stability, and reliability and could also be applied to detect the other antigens.