Effect of the transdermal low-level laser therapy on endothelial function.

The effect of low-level laser therapy (LLLT) on the cardiovascular system is not fully established. Since the endothelium is an important endocrine element, establishing the mechanisms of LLLT action is an important issue.The aim of the study was to evaluate the effect of transdermal LLLT on endothelial function.In this study, healthy volunteers (n = 40, age = 20-40 years) were enrolled. N = 30 (14 female, 16 male, mean age 30 ± 5 years) constituted the laser-irradiated group (LG). The remaining 10 subjects (6 women, 4 men, mean age 28 ± 5 years) constituted the control group (CG). Participants were subjected to LLLT once a day for three consecutive days. Blood for biochemical assessments was drawn before the first irradiation and 24 h after the last session. In the LG, transdermal illumination of radial artery was conducted (a semiconductor laser λ = 808 nm, irradiation 50 mW, energy density 1.6 W/cm(2) and a dose 20 J/day, a total dose of 60 J). Biochemical parameters (reflecting angiogenesis: vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), angiostatin; antioxidative status: glutathione (GSH) and the nitric oxide metabolic pathway: symmetric dimethylarginine (SDMA), asymmetric dimethylarginine (ADMA) and L-arginine) were assessed. In the LG, a significant increase in GSH levels and considerable decrease in angiostatin concentration following the LLLT were observed. No significant differences in levels of the VEGF, FGF, SDMA, ADMA were observed.LLLT modifies vascular endothelial function by increasing its antioxidant and angiogenic potential. We found no significant differences in levels of the nitric oxide pathway metabolites within 24 h following the LLLT irradiation.

The structure and IR signatures of the arginine-glutamate salt bridge. Insights from the classical MD simulations.

Salt bridges and ionic interactions play an important role in protein stability, protein-protein interactions, and protein folding. Here, we provide the classical MD simulations of the structure and IR signatures of the arginine (Arg)-glutamate (Glu) salt bridge. The Arg-Glu model is based on the infinite polyalanine antiparallel two-stranded ß-sheet structure. The 1 µs NPT simulations show that it preferably exists as a salt bridge (a contact ion pair). Bidentate (the end-on and side-on structures) and monodentate (the backside structure) configurations are localized [Donald et al., Proteins 79, 898-915 (2011)]. These structures are stabilized by the short (+)N-H⋯O(-) bonds. Their relative stability depends on a force field used in the MD simulations. The side-on structure is the most stable in terms of the OPLS-AA force field. If AMBER ff99SB-ILDN is used, the backside structure is the most stable. Compared with experimental data, simulations using the OPLS all-atom (OPLS-AA) force field describe the stability of the salt bridge structures quite realistically. It decreases in the following order: side-on > end-on > backside. The most stable side-on structure lives several nanoseconds. The less stable backside structure exists a few tenth of a nanosecond. Several short-living species (solvent shared, completely separately solvated ionic groups ion pairs, etc.) are also localized. Their lifetime is a few tens of picoseconds or less. Conformational flexibility of amino acids forming the salt bridge is investigated. The spectral signature of the Arg-Glu salt bridge is the IR-intensive band around 2200 cm(-1). It is caused by the asymmetric stretching vibrations of the (+)N-H⋯O(-) fragment. Result of the present paper suggests that infrared spectroscopy in the 2000-2800 frequency region may be a rapid and quantitative method for the study of salt bridges in peptides and ionic interactions between proteins. This region is usually not considered in spectroscopic studies of peptides and proteins.

Physicochemical properties of peanut protein isolate-glucomannan conjugates prepared by ultrasonic treatment.

Peanut protein isolate (PPI) was glycated with glucomannan through classical heating or ultrasound treatment in this work. The physicochemical properties of PPI-glucomannan conjugates prepared by ultrasound treatment were compared to those prepared by classical heating. Compared with classical heating, ultrasound treatment could accelerate the graft reaction between PPI and glucomannan and improve the concentration of available free amino groups of PPI. Solubility and emulsifying properties of the conjugates obtained by ultrasound treatment were both improved as compared to those obtained by classical heating and native PPI. Decreases of lysine and arginine contents during the graft reaction indicated that these two amino acid residues attended the covalent linkage between PPI and glucomannan. Structural feature analyses suggested that conjugates obtained by ultrasound treatment had less α-helix, more ß-structures and random coil, higher surface hydrophobicity and less compact tertiary structure as compared to those obtained by classical heating and native PPI.

Early changes in L-arginine-nitric oxide metabolic pathways in response to the whole-body gamma irradiation of rats.

PURPOSE: Nitric oxide (NO), a reactive radical, is formed in higher amounts from L-arginine by inducible NO synthase (iNOS) during early response to ionizing radiation presumably as a part of signal transduction pathways. This study investigated the changes in L-arginine-NO metabolic pathways within a 24-hour period after whole-body gamma irradiation of rats with the range of low to supra-lethal doses. MATERIALS AND METHODS: Young adult female Wistar rats received either 0-50 Gy whole-body irradiation or an intraperitoneal injection of bacterial lipopolysaccharide (LPS, 10 mg/kg). Exhaled NO was monitored using chemiluminiscence, nitrite + nitrate (NO(x)) and L-arginine were assayed by high-performance liquid chromatography, and expression of iNOS was determined using Western blot. RESULTS: Irradiation resulted in a dose-dependent increase of plasma NO(x) to maximum levels which were 4-fold higher compared to controls (p < 0.001). The NO(x) levels increased less in the bronchoalveolar lavage fluid (BAL) (1.7-fold, p < 0.001) and liver homogenate (2.5-fold, p < 0.05), respectively, and were dose-independent. Exhaled NO, lung NO(x), plasma and BAL L-arginine, and the expression of iNOS in lung and liver tissues of irradiated rats and controls were similar. LPS caused a considerable increase (p < 0.001) in exhaled NO (61-fold), NO(x) levels (plasma 34-fold, BAL 6-fold, lung 5-fold, liver 4-fold), and in iNOS expression, respectively. CONCLUSION: In contrast to the LPS treatment of rats, the radiation-induced changes in L-arginine-NO metabolic pathways are modest, particularly in the airways and lungs. Noninvasive measurement of exhaled NO within a 24-h period following the exposure of rats to ionizing radiation has no value for biodosimetry.

Spectral studies on Ag8+ ions irradiated LAHCl·H2O and LAHBr·H2O single crystals.

L-arginine hydrochloride monohydrate and L-arginine hydrobromide monohydrate single crystals are irradiated by 100 MeV Ag8+ swift heavy ions. The residual gases liberated from the irradiated samples are monitored as a function of ion fluence using quadrupole mass analyzer. The C2H3+, C2H2, N2, CO, HCl and CO2 are the dominant gases liberated. Fourier transform infrared spectra of irradiated crystals explain the breaking of bonds in a localized region of the crystals. The crystallinity of irradiated crystals is analyzed by powder X-ray diffractions.

Cycloheximide suppresses radiation-induced apoptosis in MOLT-4 cells with Arg72 variant of p53 through translational inhibition of p53 accumulation.

The human T-cell leukemia cell line MOLT-4 is highly radiosensitive, and thus it is often used as a model of p53-dependent radiation-induced apoptosis. Two branches of the p53-mediated apoptotic pathway are reported: "transcription-dependent" and "transcription-independent." However, the relative contribution of each in different types of cells is not yet clearly defined. Moreover, recent studies have shown that the codon 72 polymorphic variants of p53 show different sensitivities to apoptosis signals. The Arg72 variant has a more potent apoptosis-inducing activity in mitochondria than the Pro72 variant. Here, we initially investigated the codon 72 polymorphism of p53 in MOLT-4 cells. Analysis of the p53 exon 4 genomic DNA sequence, which includes codon 72, revealed that MOLT-4 cells are homozygous for the allele encoding Arg72. We next investigated the involvement of the transcription-independent function of p53 using an RNA synthesis inhibitor, actinomycin D (ActD), and a protein synthesis inhibitor, cycloheximide (CHX), and found that the apoptosis was suppressed by CHX but not by ActD. We also revealed that the suppressive effect of CHX on apoptosis was specifically mediated by p53, using a p53-knockdown MOLT-4 transfectant. Furthermore, the suppressive effect of CHX on apoptosis was highly correlated with the suppression of p53 protein accumulation, and less correlated with the suppression of p53 target genes expression. These results indicated that p53 transactivation is not necessary to induce apoptosis, and that p53 protein accumulation itself is both necessary and sufficient to do so.

Evaluation of the role of the pharmacological inhibition of Staphylococcus aureus multidrug resistance pumps and the variable levels of the uptake of the sensitizer in the strain-dependent response of Staphylococcus aureus to PPArg(2)-based photodynamic inactivation.

The emergence of antibiotic resistance among pathogenic bacteria has caused an urgent need for the development of alternative therapeutics. One possibility is a combination of nontoxic photosensitizers (PS) and visible light, recognized as photodynamic therapy. Although it is known that Staphylococcus aureus is susceptible to photodynamic inactivation (PDI), the factors that determine the emerging variation among strains in the response to the treatment remain unclear. Some data indicate that cationic photosensitizing dyes such as phenothiaziniums which vary a lot in the chemical structure might target multidrug resistance pumps. In this study, we analyzed whether the uptake and activity of the multidrug resistance pumps might influence the previously observed variations among the clinical strains to protoporphyrin-derived, amphipilic protoporphyrin diarginate-mediated photodynamic treatment (12 J cm(-2) ). Using a new set of four additionally selected methicillin-resistant and methicillin-susceptible clinical as well as ATCC S. aureus strains we confirmed that the bactericidal effect of the PDI is strain-dependent as it ranged from 0 to 5 log(10) -unit reduction in viable counts. However, neither the variable levels of the uptaken PS nor the pharmacological inhibition of NorA efflux pump explained such a phenomenon.

Fabrication of a biodegradable polysaccharide hydrogel with riboflavin, vitamin B2, as a photo-initiator and L-arginine as coinitiator upon UV irradiation.

The objective of this study is to develop a completely natural material based photo-initiation system for fabricating biologically compatible hydrogels, that is, free of any synthetic materials like conventional synthetic photo-initiators. The resulting biodegradable hydrogels would be completely free of conventional toxic synthetic substances. Dextran-based precursor was used as a model system for this study. The natural material based photo-initiation system used riboflavin (vitamin B2) as photo-initiator and L-arginine as a coinitiator. Dextran-methacrylate precursor was prepared to introduce photosensitive unsaturated moieties into dextran for subsequent photo-induced gel formation. Riboflavin alone could not initiate the photo-crosslinking reaction of the dextran methacrylate solution upon UV irradiation. L-arginine, which can act as an electron donor in the photo-initiation process, was used as a coinitiator. The optimum gel formulation conditions in terms of the concentrations of riboflavin and L-arginine as well as different pH media were extensively investigated. The dextran-methacrylate hydrogels were formed well and fast at low riboflavin concentration range (0.2-1 wt %), and L-arginine promoted the photo-initiation at all concentrations. The gelation was promoted most in the neutral pH and the least in the alkaline pH. The turbidity of the dextran-methacrylate hydrogel precursor solution affected the polymerization because UV penetration was significantly hindered as the opacity of the solution increased. The swelling property and structural visualization of the prepared hydrogels were also investigated.

Copper(II) complexes of L-arginine as netropsin mimics showing DNA cleavage activity in red light.

Copper(II) complexes [Cu(L-arg)(2)](NO(3))(2) (1) and [Cu(L-arg)(B)Cl]Cl (2-5), where B is a heterocyclic base, namely, 2,2'-bipyridine (bpy, 2), 1,10-phenanthroline (phen, 3), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 4), and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 5), are prepared and their DNA binding and photoinduced DNA cleavage activity studied. Ternary complex 3, structurally characterized using X-ray crystallography, shows a square-pyramidal (4 + 1) coordination geometry in which the N,O-donor L-arginine and N,N-donor 1,10-phenanthroline form the basal plane with one chloride at the elongated axial site. The complex has a pendant cationic guanidinium moiety. The one-electron paramagnetic complexes display a metal-centered d-d band in the range of 590-690 nm in aqueous DMF. They show quasireversible cyclic voltammetric response due to the Cu(II)/Cu(I) couple in the range of -0.1 to -0.3 V versus a saturated calomel electrode in a DMF-Tris HCl buffer (pH 7.2). The DNA binding propensity of the complexes is studied using various techniques. Copper(II) bis-arginate 1 mimics the minor groove binder netropsin by showing preferential binding to the AT-rich sequence of double-strand (ds) DNA. DNA binding study using calf thymus DNA gives an order: 5 (L-arg-dppz) > or = 1 (bis-L-arg) > 4 (L-arg-dpq) > 3 (L-arg-phen) >> 2 (L-arg-bpy). Molecular docking calculations reveal that the complexes bind through extensive hydrogen bonding and electrostatic interactions with ds-DNA. The complexes cleave supercoiled pUC19 DNA in the presence of 3-mercaptopropionic acid as a reducing agent forming hydroxyl ((*)OH) radicals. The complexes show oxidative photoinduced DNA cleavage activity in UV-A light of 365 nm and red light of 647.1 nm (Ar-Kr mixed-gas-ion laser) in a metal-assisted photoexcitation process forming singlet oxygen ((1)O(2)) species in a type-II pathway. All of the complexes, barring complex 2, show efficient DNA photocleavage activity. Complexes 4 and 5 exhibit significant double-strand breaks of DNA in red light of 647.1 nm due to the presence of two photosensitizers, namely, L-arginine and dpq or dppz in the molecules.

Time-resolved photodissociation of singly protonated peptides with an arginine at the N-terminus: a statistical interpretation.

Time-evolution of product ion signals in ultraviolet photodissociation (UV-PD) of singly protonated peptides with an arginine at the N-terminus was investigated by using a tandem time-of-flight mass spectrometer equipped with a cell floated at high voltage. Observation of different time-evolution patterns for different product ion types--an apparently nonstatistical behavior--could be explained within the statistical framework by invoking consecutive formation of some product ions and broad internal energy distributions for precursor ions. a(n) + 1 and b(n) ions were taken as the primary product ions from this type of peptide ions. Spectral characteristics in post-source decay, UV-PD, and collisionally activated dissociation at low and high kinetic energies could be explained via rough statistical calculation of rate constants. Specifically, the striking characteristics in high-energy CAD and UV-PD--dominance of a(n) and d(n) formed via a(n) + 1--were not due to the peculiarity of the excitation processes themselves, but due to quenching of the b(n) channels caused by the presence of arginine.

Piezoelectric coefficients d14, d16, d34 and d36 of an L-arginine hydrochloride monohydrate crystal by X-ray three-beam diffraction.

Previous work employed X-ray three-beam diffraction techniques to obtain part of the L-arginine hydrochloride monohydrate (L-AHCL.H(2)O) piezoelectric coefficients, namely d(21), d(22), d(23) and d(25). Those coefficients were obtained by measuring the shift in the angular position of a number of secondary reflections as a function of the electric field applied in the [010] piezoelectric direction. In this paper a similar procedure has been used to measure the remaining four piezoelectric coefficients in L-AHCL.H(2)O: with the electric field applied in the [100] direction, d(14) and d(16) were measured; with the electric field applied in the [001] direction, d(34) and d(36) were obtained. Therefore the entire piezoelectric matrix of the L-AHCL.H(2)O crystal has been successfully measured.

Radiolytic modification of basic amino acid residues in peptides: probes for examining protein-protein interactions.

Protein footprinting utilizing hydroxyl radicals coupled with mass spectrometry has become a powerful technique for mapping the solvent accessible surface of proteins and examining protein-protein interactions in solution. Hydroxyl radicals generated by radiolysis or chemical methods efficiently react with many amino acid residue side chains, including the aromatic and sulfur-containing residues along with proline and leucine, generating stable oxidation products that are valuable probes for examining protein structure. In this study, we examine the radiolytic oxidation chemistry of histidine, lysine, and arginine for comparison with their metal-catalyzed oxidation products. Model peptides containing arginine, histidine, and lysine were irradiated using white light from a synchrotron X-ray source or a cesium-137 gamma-ray source. The rates of oxidation and the radiolysis products were primarily characterized by electrospray mass spectrometry including tandem mass spectrometry. Arginine is very sensitive to radiolytic oxidation, giving rise to a characteristic product with a 43 Da mass reduction as a result of the loss of guanidino group and conversion to gamma-glutamyl semialdehyde, consistent with previous metal-catalyzed oxidation studies. Histidine was oxidized to generate a mixture of products with characteristic mass changes primarily involving rupture of and addition to the imidazole ring. Lysine was converted to hydroxylysine or carbonylysine by radiolysis. The development of methods to probe these residues due to their high frequency of occurrence, their typical presence on the protein surface, and their frequent participation in protein-protein interactions considerably extends the utility of protein footprinting.

[Mutation induced by space conditions in Escherichia coli strains].

To study the mutagenesis of microorganism under space conditions, three Escherichia coli strains CSH108, A2 and A3, were flown on board the Chinese recoverable satellite (JB1 - B9611020) in Oct . 1996. Three ways of sample boarding were designed . After recovery, survival and frequency of lacI- mutation and Arg+ reversion were determined in the flight strains. The results showed that: E. coli strains could survive after the flight conditions. The lacI- mutation frequency of A3 strain in the biocabin was sixty - seven times that of the ground control, the Arg+ reversion frequency of CSH108 in the lead chamber, was ten times that of the ground control; and among the revertants the mutation frequency of non-sense suppressor increased remarkably. The results indicate that the space conditions may greatly enhance the mutation frequency of certain genes in the microorganism and may provide an effective method for microorganism breeding.

[Synthesis of oligopeptides from the polar amino acids in water media by the combined action of weak electric and magnetic fields]. / Sintez oligopeptidov iz poliarnykh aminokislot v vodnoi srede pri kombinirovannom deistvii slabykh élektricheskikh i magnitnykh polei.

The effect of weak electromagnetic fields on aqueos solutions of polar amino acids leads to the formation of stable products of the amino acid condensation reaction. These products have a definite amino acid composition and retention time in high-performance liquid chromatography.

Mutation induction and mutation frequency decline in halogen light-irradiated Escherichia coli K-12 AB1157 strains.

The effects of halogen light irradiation on reversion of argE3-->Arg+ in E. coli K12 strain AB1157 and its mfd- mutant, and on mutation frequency decline (MFD) after transiently incubating irradiated bacteria under non-growing conditions were studied. The induction of mutations, the mutational specificity, and the MFD effect had the same characteristic features as those seen in E. coli B strains after irradiation with 254 nm UV light. MFD which is due to repair of premutagenic lesion in the transcribed strand of glnU gene and prevents mutations leading to supB formation, was not observed in halogen light-induced mutations in the mfd-1 strain. Overproduction of UmuD'C proteins led to a large increase in mutation frequency, which was much greater in mfd- than in mfd+ strains. In bacteria irradiated with halogen light and incubated immediately in a rich medium to express mutations, the formation of supB predominated strongly over that of supE(ochre) in mfd- cells but was at a similar level in mfd+ cells. Introduction of zcf117::Tn10 to AB1157 strain makes cells more sensitive to halogen light irradiation, whereas introduction of mfd-1 does not.

Oxidative denitrification of N omega-hydroxy-L-arginine by the superoxide radical anion.

The superoxide radical anion (O2-.) produced during the catalytic activity of nitric oxide synthase (NOS) and cytochrome P-450 has been implicated in the oxidative denitrification of hydroxyguanidines ( > C = NOH). The reactivity of the radiolytically generated O2-. radical with N omega-hydroxy-L-arginine (NHA) is pH dependent and appears to parallel the prototropic equilibrium of the hydroxyguanidino group ( > C = NOH reversible > C = NO(-)+H+; pK = 8). The N omega-hydroxyguanidino group is more reactive towards O2-. when deprotonated but exhibits negligible reactivity when protonated. Based on a model, the rate constant for the reaction of the O2-. with NHA was estimated as kappa (O2-.+ > C = NO-) approximately 200-500 M-1.s-1, which is probably too low to compete with O2-. reactions with NO- or superoxide dismutase, which occur many orders of magnitude faster. The oxidative elimination of NO from NHA by O2-. was not accompanied by the formation of L-citrulline. Since only 21% of NHA will exist in the deprotonated > C = NO- form at physiological pH, it is unlikely that oxidative denitrification of NHA by cytochrome P-450 or NOS-derived O2-. radicals will prove a major free-radical pathway to NO. and L-citrulline.

Photochemical generation of nitric oxide from nitro-containing compounds: possible relation to vascular photorelaxation phenomena.

We examined the production of nitric oxide (NO) from various nitro-containing compounds (500 microM and 100 microM solutions in Krebs buffer, pH 7.4). Sealed vials containing solutions of NaNO2, N-nitro-L-arginine, 4-nitrophenol, BAY K 8644, or N-nitro-L-arginine methyl ester were stored in the dark, under normal room light, or were exposed to ultraviolet light (365 nm), for 30 min (24 degrees C). NO was measured in the vial headspace after 30 min, using a sensitive assay previously established in our laboratory. Production of NO was found to be dependent on the intensity of light exposure for all compounds, and the highest degree of light-induced production of NO was found for NaNO2 and BAY K 8644 solutions. Since NO is a relaxant of smooth muscle, these results help explain the increased sensitivity to relaxation by UV light of vascular and other types of smooth muscle in the presence of NaNO2, BAY K 8644 and N-nitro-L-arginine, as observed by other investigators.