Spectroscopic investigations of high-power laser-induced dielectric breakdown in gas mixtures containing carbon monoxide.

Large-scale plasma was created in gas mixtures containing carbon monoxide by high-power laser-induced dielectric breakdown (LIDB). The composition of the mixtures used corresponded to a cometary and/or meteoritic impact into the Earth's early atmosphere. A multiple-centimeter-sized fireball was created by focusing a single 85 J, 450 ps near-infrared laser pulse into the center of a 15 L gas cell. The excited reaction intermediates that formed in various stages of the LIDB plasma chemical evolution were investigated by optical emission spectroscopy (OES) with temporal resolution. Special attention was paid to any OES signs of molecular ions. However, carbon monoxide cations were registered only if their production was enhanced by Penning ionization, i.e., excess He was added to the CO. The chemical consequences of laser-produced plasma generation in a CO-N 2-H 2O mixture were investigated using high resolution Fourier-transform infrared absorption spectroscopy (FTIR) and gas chromatography (GC). Several simple inorganic and organic compounds were identified in the reaction mixture exposed to ten laser sparks. H 2 (18)O was used to avoid possible contamination. The large laser spark triggered more complex reactivity originating in carbon monoxide than expected, when taking into account the strong triple bond of carbon monoxide causing typically inefficient dissociation of this molecule in electrical discharges.

A high-power laser-driven source of sub-nanosecond soft X-ray pulses for single-shot radiobiology experiments.

A large-scale, double-stream gas puff target has been illuminated by sub-kJ, near-infrared (NIR) focused laser pulses at the PALS facility (Prague Asterix Laser System) to produce high-energy pulses of soft X rays from hot, dense plasma. The double-puff arrangement ensures high gas density and conversion efficiency from NIR to X rays approaching that typical for solid targets. In addition, its major advantage over solid targets is that it is free of debris and has substantially suppressed charged-particle emission. The X-ray emission characteristics of the source were determined for a range of gases that included krypton, xenon, N(2), CO and N(2)-CO. A demonstrated application of the xenon-based source is a single-shot damage induction to plasmid DNA. The yields of single-strand breaks (SSBs) and double-strand breaks (DSBs) were determined as a function of energy fluence adjusted by varying distance of sample from the source and thickness of aluminum filters.

Deletion of transient receptor potential vanilloid type 1 receptors exaggerates renal damage in deoxycorticosterone acetate-salt hypertension.

To determine whether the transient receptor potential vanilloid type 1 (TRPV1) channel provides protection against hypertension-induced renal damage, hypertension was induced by uninephrectomy and by giving deoxycorticosterone acetate (DOCA)-salt in wild-type (WT) and TRPV1-null mutant (TRPV1-/-) mice. Mean arterial pressure, as determined by radiotelemetry, increased significantly and reached the peak 7 days after DOCA-salt treatment in both WT and TRPV1-/- mice. There was no difference in mean arterial pressure between the 2 strains at the baseline or at the peak that lasted for 4 treatment weeks. DOCA-salt treatment in both WT and TRPV1-/- mice led to increased urinary excretion of albumin and 8-isoprostane, glomerulosclerosis, renal cortical tubulointerstitial injury, tubulointerstitial fibrosis, increased number of tubular proliferating cell nuclear antigen-positive cells, and renal monocyte/macrophage infiltration, all of which were much more severe in DOCA-salt-treated TRPV1-/- compared with DOCA-salt-treated WT mice. Renal TRPV1 protein expression, but not the renal anandamide content, was elevated in DOCA-salt-treated WT compared with vehicle-treated WT mice. Renal anandamide levels were markedly elevated in DOCA-salt-treated TRPV1-/- but not in vehicle-treated TRPV1-/- mice. Thus, our data show that ablation of the TRPV1 gene exacerbates renal damage induced by DOCA-salt hypertension, indicating that TRPV1 may constitute a protective mechanism against end-organ damage induced by hypertension.

Cardiac norepinephrine transporter protein expression is inversely correlated to chamber norepinephrine content.

The cardiac neuronal norepinephrine (NE) transporter (NET) in sympathetic neurons is responsible for uptake of released NE from the neuroeffector junction. The purpose of this study was to assess the chamber distribution of cardiac NET protein measured using [(3)H]nisoxetine binding in rat heart membranes and to correlate NE content to NET amount. In whole mounts of atria, NET was colocalized in nerve fibers with tyrosine hydroxylase (TH) immunoreactivity. NE content expressed as micrograms NE per gram tissue was lowest in the ventricles; however, NET binding was significantly higher in the left ventricle than the right ventricle and atria (P < 0.05), resulting in a significant negative correlation (r(2) = 0.922; P < 0.05) of NET to NE content. The neurotoxin 6-hydroxydopamine, an NET substrate, reduced NE content more in the ventricles than the atria, demonstrating functional significance of high ventricular NET binding. In summary, there is a ventricular predominance of NET binding that corresponds to a high NE reuptake capacity in the ventricles, yet negatively correlates to tissue NE content.

Optical and X-ray emission spectroscopy of high-power laser-induced dielectric breakdown in molecular gases and their mixtures.

Large-scale plasma was created in molecular gases (CO, CO2, N2, H2O) and their mixtures by high-power laser-induced dielectric breakdown (LIDB). Compositions of the mixtures used are those suggested for the early earth's atmosphere of neutral and/or mildly reducing character. Time-integrated optical spectra emitted from the laser spark have been measured and analyzed. The spectra of the plasma generated in the CO-containing mixtures are dominated by emission of both C2 and CN radicals. A vibrational temperature of approximately 10(4) K was determined according to an intensity distribution in a vibronic structure of the CN (B2Sigma(+)u-X2Sigma(+)g) violet band. For comparison, the NH3-CH4-H2-H2O mixture has been irradiated as a model of the strongly reducing version of the early earth's atmosphere. In this mixture, excited CN seems to be significantly less abundant than C2. The LIDB experiments were in the molecular gases carried out not only in the static cell but also using a large, double stream pulse jet (gas puff target) placed in the vacuum interaction chamber. The obtained soft X-ray emission spectra indicate the presence of highly charged atomic ions in the hot core of high-power laser sparks.