bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity-dependent NFATc3 nuclear accumulation in pericytes from cortical parenchymal microvessels
Authors: Filosa Jessica A. , Nelson Mark T. , Gonzalez Bosc Laura V.
Published: September 2007

The calcium-dependent transcription factor NFATc3, which is a member of the nuclear factor of activated T cells (NFAT) family of transcription factors, is critical for embryonic vascular development and differentiation. Despite its potential importance, nothing is known about NFATc3 regulation in the brain microcirculation. In the present study, we sought to investigate the role that glutamate, possibly through astrocytic communication, plays in the control of NFATc3 regulation in pericytes from parenchymal microvessels. Coronal cortical slices from neonatal rats were subjected to electrical field stimulation or were treated with the metabotropic glutamate receptor agonist (±)-1-aminocyclopentane- trans-1,3-dicarboxylic acid ( t-ACPD). NFATc3, glial fibrillary acidic protein (an astrocyte-specific marker), and platelet-derived growth factor-β-receptor (a pericyte-specific marker) were detected by immunofluorescence. Electrical field stimulation induced NFATc3 nuclear accumulation in pericytes. This response was dependent on neuronal activity and group I metabotropic glutamate receptor (mGluR) activation. In addition, t-ACPD significantly increased NFATc3 nuclear accumulation in both astrocytes and pericytes. NFATc3 nuclear accumulation in pericytes was prevented when astrocytic function was abolished with the gliotoxin l-α-aminoadipate or by the inhibition of calcineurin, cyclooxygenase, and nitric oxide synthase. This is the first study to report NFATc3 expression in pericytes from parenchymal microvessels and in astrocytes from native tissue. Our results suggest a model by which glutamate, via mGluR activation, may regulate gene transcription in pluripotent vascular pericytes.
Alterations of NOS, arginase, and DDAH protein expression in rabbit cavernous tissue after administration of cigarette smoke extract
Authors: Imamura Masatoshi , Waseda Yuma , Marinova Galina Vasileva , Ishibashi Tomoko , Obayashi Satoshi , Sasaki Akihito , Nagai Akiko , Azuma Hiroshi
Published: September 2007

Cigarette smoking is an independent risk factor for vasculogenic erectile dysfunction (ED). Nitric oxide (NO) has been demonstrated to be the principal mediator of cavernous smooth muscle relaxation and penile erection. Therefore, we examined whether or not enzyme activities and factors involved in the NO generation pathway are affected in rabbit corpus cavernosum after administration of nicotine- and tar-free cigarette smoke extract (CSE). CSE was prepared by bubbling a stream of cigarette smoke into phosphate-buffered saline. CSE was injected subcutaneously into adult male rabbits once a day for 5 wk. In the CSE group, significantly decreased cyclic GMP production as a marker of NO generation was associated with attenuated overall nitric oxide synthase (NOS) activity, enhanced arginase activity, accumulation of endogenous NOS inhibitors such as monomethylarginine (MMA) and asymmetric dimethylarginine (ADMA), and decreased dimethylarginine dimethylaminohydrolase (DDAH) activity as an metabolizing enzyme of endogenous NOS inhibitors. Neuronal NOS (nNOS) and DDAH I protein expression were decreased without altering endothelial NOS expression, while arginase I expression was upregulated. These results suggest that impaired NO production would result from blunted NOS activity, which is possibly brought about by the downregulation of nNOS protein, accumulation of endogenous NOS inhibitors, and enhanced arginase activity together with upregulation of arginase I protein in cavernous tissue. The impaired DDAH activity due to decreased expression of DDAH I protein would result in an accumulation of endogenous NOS inhibitors with CSE. These alterations may be relevant to induction of the erectile dysfunction following CSE.
Oncostatin M-induced effects on EMT in human proximal tubular cells: differential role of ERK signaling
Authors: Pollack Verena , Sarközi Rita , Banki Zoltan , Feifel Elisabeth , Wehn Swantje , Gstraunthaler Gerhard , Stoiber Heribert , Mayer Gert , Montesano Roberto , Strutz Frank , Schramek Herbert
Published: September 2007

Growing evidence suggests that a proportion of interstitial myofibroblasts detected during renal tubulointerstitial fibrosis originates from tubular epithelial cells by a process called epithelial-mesenchymal transition (EMT). The IL-6-type cytokine oncostatin M (OSM) has been recently implicated in the induction of EMT. We investigated OSM effects on the expression of both cell-cell contact proteins and mesenchymal markers and studied OSM-induced intracellular signaling mechanisms associated with these events in human proximal tubular cells. Human recombinant OSM attenuated the expression of N-cadherin, E-cadherin, and claudin-2 in human kidney-2 (HK-2) cells associated with the induction of HK-2 cell scattering in 3D collagen matrices. Conversely, expression of collagen type I, vimentin, and S100A4 was induced by OSM. OSM-stimulated cell scattering was inhibited by antibodies against gp130. Besides inducing phosphorylation of Stat1 and Stat3, OSM led to a strong concentration- and time-dependent phosphorylation of the mitogen-activated protein kinases ERK1, ERK2, and ERK5. MEK1/2 inhibitor U0126 (10 μM) blocked basal and OSM-induced ERK1/2 phosphorylation but not phosphorylation of either ERK5 or Stat1/3. Both synthetic MEK1/2 inhibitors U0126 and Cl-1040, when used at concentrations which inhibit ERK1/2 phosphorylation but not ERK5 phosphorylation, restored N-cadherin expression in the presence of OSM, inhibited basal claudin-2 expression, but did not affect either basal or OSM-inhibited E-cadherin expression or OSM-induced expression of collagen type I and vimentin. These results suggest that in human proximal tubular cells ERK1/2 signaling represents an important component of OSM's inhibitory effect on N-cadherin expression. Furthermore, functional ERK1/2 signaling is necessary for basal claudin-2 expression.
Delayed recovery of renal regional blood flow in diabetic mice subjected to acute ischemic kidney injury
Authors: Shi Haikun , Patschan Daniel , Epstein Tracy , Goligorsky Michael S. , Winaver Joseph
Published: September 2007

Ischemic acute kidney injury in experimental diabetes mellitus (DM) is associated with a more severe deterioration in renal function than shown in nondiabetic animals. We evaluated whether the early recovery phase from acute kidney injury is associated with a more prolonged and sustained decrease in renal perfusion in diabetic mice, which could contribute to the impaired recovery of renal function. Perfusion to the renal cortex and medulla was evaluated by laser-Doppler flowmetry in 10- to 12-wk-old anesthetized mice with type 2 DM ( db/db), heterozygous mice ( db/m), and nondiabetic (control) mice (C57BL/6J). After baseline measurements were obtained, the right renal artery was clampedfor 20 min followed by reperfusion for 60 min. The data demonstrated that, in all three groups studied, the reperfusion phase was characterized by a significant increase in the medullary-to-cortical blood flow ratio. Moreover, during recovery from ischemia, there was a marked prolongation in the time (in min) required to reach peak reperfusion in the cortex ( db/db: 20.7 ± 4.0, db/m: 12.92 ± 1.9, C57BL/6J: 9.3 ± 1.3) and the medulla ( db/db: 20.8 ± 3.2, db/m: 12.88 ± 1.89, C57BL/6J: 11.2 ± 1.2). Additionally, the slope of the recovery phase was lower in db/ db mice (cortex: 61.9 ± 23.1%/min, medulla: 16.3 ± 3.6%/min) than in C57BL/6J mice (cortex: 202.2 ± 41.6%/min, medulla: 42.1 ± 7.2%/min). Our findings indicate that renal ischemia is associated with a redistribution of blood flow from cortex to medulla, not related to DM. Furthermore, renal ischemia in db/db mice results in a marked impairment in reperfusion of the renal cortex and medulla during the early postischemic period.
Vesico-ureteric reflux and urinary tract development in thePax21Neu+/−mouse
Authors: Murawski Inga J. , Myburgh David B. , Favor Jack , Gupta Indra R.
Published: September 2007

Vesico-ureteric reflux (VUR) is a urinary tract abnormality that affects roughly one-third of patients with renal-coloboma syndrome, an autosomal dominant condition caused by a mutation in PAX2. Here, we report that a mouse model with an identical mutation, the Pax21Neu+/−mouse, has a 30% incidence of VUR. In VUR, urine flows retrogradely from the bladder to the ureter and is associated with urinary tract infections, hypertension, and renal failure. The propensity to reflux in the Pax21Neu+/−mouse is correlated with a shortened intravesical ureter that has lost its oblique angle of entry into the bladder wall compared with wild-type mice. Normally, the kidney and urinary tract develop from the ureteric bud, which grows from a predetermined position on the mesonephric duct. In Pax21Neu+/−mice, this position is shifted caudally while surrounding metanephric mesenchyme markers remain unaffected. Mutant offspring from crosses between Pax21Neu+/−and Hoxb7/GFP+/−mice have delayed union of the ureter with the bladder and delayed separation of the ureter from the mesonephric duct. These events are not caused by a change in apoptosis within the developing urinary tract. Our results provide the first evidence that VUR may arise from a delay in urinary tract maturation and an explanation for the clinical observation that VUR resolves over time in some affected children.
Early upregulation of iNOS mRNA expression and increase in NO metabolites in pressurized renal epithelial cells
Authors: Broadbelt Nalini V. , Stahl Peter J. , Chen Jie , Mizrahi Moshe , Lal Amit , Bozkurt Alper , Poppas Dix P. , Felsen Diane
Published: September 2007

Pressure is an important physiological regulator, but under abnormal conditions it may be a critical factor in the onset and progression of disease in many organs. In vivo, proximal tubular epithelial cells are subjected to pressure as a result of ureteral obstruction, which may influence the production of nitric oxide (NO), a ubiquitous multifunctional cytokine. To directly explore the effect of pressure on the expression and activity of NO synthase (NOS) in cultured proximal tubular epithelial cells, a novel pressure apparatus was developed. Cells were subjected to pressures of 20–120 mmHg over time (5 min-72 h). RT-PCR demonstrated an increase in inducible NOS (iNOS) and sGC, while endothelial NOS remained unchanged. Real-time PCR (qPCR) confirmed an earlier induction of iNOS transcript subjected to 60 mmHg compared with cytokine mix. iNOS protein expression was significantly increased following 60 mmHg of pressure for 24 h. Use of nuclear factor-κB inhibitors was shown to prevent the increase in iNOS expression following 60 mmHg for 2 h. NO and cGMP were increased with the application of pressure. The addition of the irreversible iNOS inhibitor (1400W) was shown to prevent this increase. We demonstrate that with the use of a simply designed apparatus, pressure led to an extremely early induction of iNOS and a rapid activation of NOS activity to increase NO and cGMP in proximal tubule epithelial cells. The rapid effects of pressure on iNOS may have important implications in the obstructed kidney.
Developmental regulation of calcineurin isoforms in the rodent kidney: association with COX-2
Authors: Liu Haiying , Ye Wenling , Guan Guangju , Dong Zheng , Jia Zhanjun , Yang Tianxin
Published: September 2007

Calcineurin (Cn)-Aα-deficient mice develop abnormalities of postnatal kidney development, similar to that of cyclooxygenase (COX)-2-deficient mice. The present study was undertaken to examine expression and regulation of Cn isoforms in the developing kidney during the postnatal period and further characterize the relationship between Cn and COX-2. The protein expressions of all three Cn isoforms, including Cn-Aα, -Aβ, and -B, as determined by immunoblotting, increased in parallel in the first postnatal week and declined gradually with age. Renal Cn-Aα and -Aβ mRNA expressions were both developmentally regulated in the same fashion as their protein expressions, whereas renal Cn-B1 mRNA was not obviously induced in the first postnatal week. Immunohistochemistry demonstrated colocalization of Cn-Aα, Cn-Aβ, and COX-2 in the same cells of thick ascending limb and macula densa. Administration with cyclosporine A (2.5 mg·kg−1·day−1) during the postnatal period remarkably suppressed renal COX-2 expression as assessed by both immunoblotting and immunohistochemistry. Deletion of Cn-Aα but not Cn-Aβ in mice significantly reduced renal COX-2 expression at the postnatal period. Together, these data suggest that renal Cn isoforms are subject to normal developmental regulation and they may play a role in postnatal kidney development via interaction with COX-2.
Spatial heterogeneity of quadriceps muscle deoxygenation kinetics during cycle exercise
Authors: Koga Shunsaku , Poole David C. , Ferreira Leonard F. , Whipp Brian J. , Kondo Narihiko , Saitoh Tadashi , Ohmae Etsuko , Barstow Thomas J.
Published: September 2007

To test the hypothesis that, during exercise, substantial heterogeneity of muscle hemoglobin and myoglobin deoxygenation [deoxy(Hb + Mb)] dynamics exists and to determine whether such heterogeneity is associated with the speed of pulmonary O2 uptake (pV̇o2) kinetics, we adapted multi-optical fibers near-infrared spectroscopy (NIRS) to characterize the spatial distribution of muscle deoxygenation kinetics at exercise onset. Seven subjects performed cycle exercise transitions from unloaded to moderate [GET) work rates and the relative changes in deoxy(Hb + Mb), at 10 sites in the quadriceps, were sampled by NIRS. At exercise onset, the time delays in muscle deoxy(Hb + Mb) were spatially inhomogeneous [intersite coefficient of variation (CV), 3∼56% for GET]. The primary component kinetics (time constant) of muscle deoxy(Hb + Mb) reflecting increased O2 extraction were also spatially inhomogeneous (intersite CV, 6∼48% for GET) and faster (P < 0.05) than those of phase 2 pV̇o2. However, the degree of dynamic intersite heterogeneity in muscle deoxygenation did not correlate significantly with phase 2 pV̇o2 kinetics. In conclusion, the dynamics of quadriceps microvascular oxygenation demonstrates substantial spatial heterogeneity that must arise from disparities in the relative kinetics of V̇o2 and O2 delivery increase across the regions sampled.
Functional Magnetic Resonance Imaging in Zebra Finch Discerns the Neural Substrate Involved in Segregation of Conspecific Song From Background Noise
Authors: Boumans Tiny , Vignal Clémentine , Smolders Alain , Sijbers Jan , Verhoye Marleen , Van Audekerke Johan , Mathevon Nicolas , Van der Linden Annemie
Published: September 2007

Recently, fMRI was introduced in a well-documented animal model for vocal learning, the songbird. Using fMRI and conspecific signals mixed with different levels of broadband noise, we now demonstrate auditory-induced activation representing discriminatory properties of auditory forebrain regions in anesthetized male zebra finches ( Taeniopygia guttata). Earlier behavioral tests showed comparable calling responses to the original conspecific song stimulus heard outside and inside the magnet. A significant fMRI response was elicited by conspecific song in the primary auditory thalamo-recipient subfield L2a; in neighboring subareas L2b, L3, and L; and in the rostral part of the higher-order auditory area NCM (caudomedial nidopallium). Temporal BOLD response clustering revealed rostral and caudal clusters that we defined as “cluster Field L” and “cluster NCM”, respectively. However, because the actual border between caudal Field L subregions and NCM cannot be seen in the structural MR image and is not precisely reported elsewhere, the cluster NCM might also contain subregion L and the medial extremes of the subregions L2b and L3. Our results show that whereas in cluster Field L the response was not reduced by added noise, in cluster NCM the response was reduced and finally disappeared with increasing levels of noise added to the song stimulus. The activation in cluster NCM was significant for only two experimental stimuli that showed significantly more behavioral responses than the more degraded stimuli, suggesting that the first area within the auditory system where the ability to discern song from masking noise emerges is located in cluster NCM.
Passive Stability and Active Control in a Rhythmic Task
Authors: Wei Kunlin , Dijkstra Tjeerd M. H. , Sternad Dagmar
Published: September 2007

Rhythmically bouncing a ball with a racket is a task that affords passively stable solutions as demonstrated by stability analyses of a mathematical model of the task. Passive stability implies that no active control is needed as errors die out without requiring corrective actions. Empirical results from human performance demonstrated that actors indeed exploit this passive dynamics in steady-state performance, thereby reducing computational demands of the task. The present study investigated the response to perturbations of different magnitudes designed on the basis of the model's basin of attraction. Humans performed the task in a virtual reality set-up with a haptic interface. Relaxation times of the performance errors showed significantly faster returns than predicted from the purely passive model, indicative of active error corrections. Systematic adaptations in the racket trajectories were a monotonic function of the perturbation magnitudes, indicating that active control was applied in proportion to the perturbation. These results did not indicate any sensitivity to the boundary of stability. Yet the influence of passive dynamics was also seen: the pattern of relaxation times in the major performance variable ball height was consistent with qualitative predictions derived from the basin of attraction and racket accelerations at contact were generally negative signaling use of passive stability. These findings suggest that the fast return back to steady state was assisted by passive properties of the task. It was concluded that actors used a blend of active and passive control for all sizes of perturbations.
Different Topography of the Reticulothalmic Inputs to First- and Higher-Order Somatosensory Thalamic Relays Revealed Using Photostimulation
Authors: Lam Ying-Wan , Sherman S. Murray
Published: September 2007

The thalamic reticular nucleus is a layer of GABAergic neurons that occupy a strategic position between the thalamus and cortex. Here we used laser scanning photostimulation to compare in young mice (9–12 days old) the organization of the reticular inputs to first- and higher-order somatosensory relays, namely, the ventral posterior lateral nucleus and posterior nucleus, respectively. The reticulothalamic input footprints to the ventral posterior lateral nucleus neurons consisted of small, single, topographically organized elliptical regions in a tier away from the reticulothalamic border. In contrast, those to the posterior nucleus were complicated and varied considerably among neurons: although almost all contained a single elliptical region near the reticulothalamic border, in most cases, they consisted of additional discontinuous regions or relatively diffuse regions throughout the thickness of the thalamic reticular nucleus. Our results suggest two sources of reticular inputs to the posterior nucleus neurons: one that is relatively topographic from regions near the reticulothalamic border and one that is relatively diffuse and convergent from most or all of the thickness of the thalamic reticular nucleus. We propose that the more topographic reticular input is the basis of local inhibition seen in posterior nucleus neurons and that the more diffuse and convergent input may represent circuitry through which the ventral posterior lateral and posterior nuclei interact.
Lack of Depolarization-Induced Suppression of Inhibition (DSI) in Layer 2/3 Interneurons That Receive Cannabinoid-Sensitive Inhibitory Inputs
Authors: Lemtiri-Chlieh Fouad , Levine Eric S.
Published: September 2007

In layer 2/3 of neocortex, brief trains of action potentials in pyramidal neurons (PNs) induce the mobilization of endogenous cannabinoids (eCBs), resulting in a depression of GABA release from the terminals of inhibitory interneurons (INs). This depolarization-induced suppression of inhibition (DSI) is mediated by activation of the type 1 cannabinoid receptor (CB1) on presynaptic terminals of a subset of INs. However, it is not clear whether CB1 receptors are also expressed at synapses between INs, and whether INs can release eCBs in response to depolarization. In the present studies, brain slices containing somatosensory cortex were prepared from 14- to 21-day-old CD-1 mice. Whole cell recordings were obtained from layer 2/3 PNs and from INs classified as regular spiking nonpyramidal, irregular spiking, or fast spiking. For all three classes of INs, the cannabinoid agonist WIN55,212-2 suppressed inhibitory synaptic activity, similar to the effect seen in PNs. In addition, trains of action potentials in PNs resulted in significant DSI. In INs, however, DSI was not seen in any cell type, even with prolonged high-frequency spike trains that produced calcium increases comparable to that seen with DSI induction in PNs. In addition, blocking eCB reuptake with AM404, which enhanced DSI in PNs, failed to unmask any DSI in INs. Thus the lack of DSI in INs does not appear to be due to an insufficient increase in intracellular calcium or enhanced reuptake. These results suggest that layer 2/3 INs receive CB1-expressing inhibitory inputs, but that eCBs are not released by these INs.
Characterization of Inhibitory Circuits in the Malformed Hippocampus ofLis1Mutant Mice
Authors: Jones Daniel L. , Baraban Scott C.
Published: September 2007

Heterozygous mutation or deletion of a lissencephaly gene ( Lis1) in humans is associated with a severe disruption of cortical and hippocampal lamination, cognitive deficit, and severe seizures. Mice with one null allele of Lis1 ( Lis1+/–mice) exhibit significant brain malformations and slowed migration of interneuron precursors. Although hyperexcitability was demonstrated in dysplastic hippocampal slices from Lis1+/–mice, little is known about synaptic function in these animals. Here we analyzed GABA-mediated synaptic inhibition. We recorded isolated whole cell inhibitory postsynaptic currents (IPSCs) on visually identified pyramidal neurons in disorganized CA1 regions of hippocampal slices prepared from Lis1+/–mice. We observed a 32% increase in spontaneous IPSC frequency in Lis1+/–mice compared with normotopic CA1 pyramidal neurons in age-matched controls. This increase was not associated with a change in spontaneous IPSC decay or miniature IPSC frequency. Mean IPSC amplitude was increased, and event histograms indicated a greater number of large (>125 pA) events. Tonic inhibition, response to paired-pulse stimulation and evoked IPSC decay kinetics were not altered. Consistent with increased synaptic inhibition, Lis1+/–interneurons also exhibited more spontaneous firing in cell-attached recordings and increased excitation as measured by voltage-clamp recording of spontaneous excitatory postsynaptic currents (EPSCs) onto interneurons. Our results reveal a significant alteration in the function of inhibitory circuits within the malformed Lis1+/–hippocampus. Given that precisely coordinated GABAergic activity is vital to generation of oscillatory activity and place field precision in hippocampus, these alterations in synaptic inhibition may contribute to seizures and altered cognitive function in type I Lissencephaly.
Reaction Dynamics of Translationaland Electronic Excitation In Ca + SF6Collisions
Authors: Verdasco E. , Rabanos V. Saez , Ureña A. Gonzalez
Published: September 2007

Relative values of the total chemiluminescence cross.section for the crossed molecular beam

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reaction have been measured as a function of collision energy. Both metastable calcium
atom states 3P1
were produced by low voltage de‐discharge while translational excitation of the SF6
beam was achieved via the seeding technique. Whereas chemiluminescence yield from the

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was
observed from both of the metastable atom reactions, no chemiluminescence signal was detected from the
ground atom reaction even though enough translational excitation was used to produc.e that excited
product. By changing the discharge conditions different metastable concentrations were produced to
measure the state‐to‐state cross‐section for both 3P and 1D reactions, as a function of collision energy, up
to 0.6 eV. Laser induced fluorescence of the atomic 4s5s 3S1 ← 4s4p(J = 0, 1, 2, 3) lines have been
measured to account for the metastable population in the J = 1 level.
Change In Total Angular Momentum Within The Z3F0 Titanium Excited StateInduced By Collisions With Hydrogen And Nitrogen Molecules
Authors: Quichaud V. , Dézert D. , Aubreton J. , Degout D. , Catherinot A.
Published: September 2007

Collisions that produce a change in the total angular‐momentum and quenching processes involving the
triplet Z3F0 titanium excited level and diatomic molecules have been studied by laser perturbation and
time‐resolved spectroscopy. The thermally averaged total angular‐momentum changing cross sections
in units of

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, respectively, for nitrogen and hydrogen colliding partners.

Large quenching cross sections are obtained, as , and in units of 10-16 cm2.
These results are discussed in relation with previous measurements dealing with titanium‐noble‐gas
collisions, and with available published results.
Chemiluminescent Emission in the Reaction Ba(6s6p1P1) + CO2 → BaO*+CO
Authors: Visticot J. P. , Meynadier P. , Cuvellier J. , Binet A. , Mestdagh J. M.
Published: September 2007

The chemiluminescence of BaO in the range 600‐800 nm has been observed for the first time in the
reaction between Ba(6s6p1P1) and CO2 in a crossed beam experiment under single collision conditions.
The observed spectrum is attributed to the emission from the A1Σ+ state of BaO and no emission from the
A'1Π is visible under our experimental conditions. The distribution of low ν′ in the

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state appears
statistical at low collision energy and, at higher collision energy, the

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appears less populated than
statistically predicted.
Kinetics and Mechanism of the Photochromism of N‐Phenyl‐Rhodaminelactame
Authors: Willwohl H. , Wolfrum J. , Gleiter R.
Published: September 2007

The photochromism of N‐phenyl‐rhodaminelactame (3′ ,6′ ‐bis‐(diethylamino)‐2‐phenyl‐spiro[1H‐isoindole‐1,9′[9H] Xanthaen]‐3‐[2H]‐one) was investigated in solutions of acetonitrile, dioxane and
mixtures of dioxane with H20, methanol and ethanol by laser flash time resolved absorption measurements.
The colouring reaction kinetics and the relative quantum yield of the red product were measured
using nanosecond excimer laser excitation at 308 nm. In most cases, first order kinetics was.observed. The
first order rate constants and the quantum yield were found to be dependent on the solvent and the
number of laser pulses that had previously irradiated the solution. The thermal fading reaction occurred
on a millisecond timescale and showed large deviations from first order kinetics in all solvents. In addition,
picosecond laser pulses at 285 nm were used to measure the fluorescence lifetime of the S1 state of
the rhodamine derivative with picosecond resolution. Single exponential decays were observed in all
solvents and the lifetime ranged between 3 and 6 nanoseconds. We conclude that the photoreaction does
not proceed directly from the S1 state, and propose a mechanism for the photochromic process, in which
an intermediate decomposes to rotameric isomers of the coloured product, which are not equilibrated on
the millisecond time scale of the reverse reaction.
Boron Particles Production inNonequilibrium Laser‐Chemical RadicalReactions During the IR MultiphotonDissociation of HCIC=CBCI2H Molecules
Authors: Abdushelishvili G. I. , Abzianidze T. G. , Bakhtadze A. G. , Kervalishvili P. D. , Tkeshelashvili G. I. , Tzinadze T. B.
Published: September 2007

The study of IR MPD of HCIC=CBCI2H molecule by CO2.‐laser is presented. We provide experimental
results showing high degree of fragmentation of this molecule (down to elementary boron) during
nonequilibrium laser induced radical bimolecular reactions.
Effects of Molecular Vibration andRotation on Intramolecular Dynamics in S1 of s‐Triazine Vapor
Authors: Ohta Nobuhiro
Published: September 2007

Emission properties of s‐triazine vapor have been examined for excitation into various vibronic levels of
S1. The emission involves broad fluorescence besides the sharp fluorescence emitted from the initially
prepared vibronic level (IPL). At low pressures, the IPL fluorescence exhibits a biexponential decay
composed of fast and slowly decaying portions, and the broad fluorescence also consists of fast and slow
components with lifetimes comparable to those of the IPL fluorescence. The broad fluorescence exhibits
another slow component, which is characterized by a less tendency to undergo collisional quenching. The
emitting levels of the broad fluorescence are regarded as reached directly from the IPL and indirectly via
triplet state. The quantum yield of the slow component of the IPL fluorescence remarkably depends on the
rotational level excited, whereas the quantum yield of the broad fluorescence is nearly independent of the
rotational level excited. These results suggest that K scrambling occurs not only in the intersystem crossing
between singlet and triplet levels but also in the relaxation to other singlet levels from the IPL.
Anionic and Zwitterionic Photophysical Effects in Some Pyridinium Oxazole Laser Dyes
Authors: Kubin R. F. , Henry R. A. , Pietrak M. E. , Bliss D. E. , Hall J. H.
Published: September 2007

Kauffman and Bentley [Laser Chem. 8, 49‐59 (1988)] have reported increased laser output by changing
the anion of certain pyridinium oxazole dyes from the tosylate to the mesylate salt. Likewise, zwitterion
variants of these dyes are also reported to have a significantly improved laser output. We find anion
changes to be modest and, with one exception, all zwitterions tested were no better or not as good as the
tosylate salt with respect to lasing output. However, both the mesylate salt and the zwitterion variants
have greatly improved lifetimes if there is no fluorine auxochrome in the basic dye. These authors also
report observation of bifurcated lasing output curves. We see no such phenomena.
Laser Photolysis Investigations of Ligand Binding With Models of the Active Site ofRespiratory Hemoproteins: Kinetic and Thermodynamic Aspects
Authors: Lavalette D. , Tetreau C. , Momenteau M. , Mispelter J. , Lhoste J. M. , Wuenschell G. E. , Reed C.
Published: September 2007

During the past 15 years, laser photolysis has been the method of choice for probing the complex
reaction kinetics of respiratory proteins. In an attempt to determine the structural parameters which
govern their reactivity, synthetic heme model compounds capable of simulating particular aspects of the
reactivity of the active site of hemoproteins have been successively proposed. Laser photolysis of heme
compounds merely induces a reversible photodissociation of one ligand at a time. This is equivalent to
performing a fast concentration jump "in situ" and provides a powerful, fast and "clean" chemical
relaxation technique. To gather association and dissociation rate constants of various ligands (O2, CO,
nitrogenous bases) special methods have been developed or adapted. The problem of comparing and
classifying a large number of collected data has been greatly simplified by introducing a Linear Free
Energy Relationships formalism. In the first part of this paper, some of the methods and concepts which
have emerged from several years of investigations of heme proteins and heme models and which are of a
sufficient generality to be useful in other fields of chemical kinetics are reviewed. In the second part of the
paper we present the application of the preceding methods to a kinetic study of a series of heme models
which were specifically designed to investigate the important problem of H‐bonding as a stabilizing factor
of the oxygenated heme model and hemoprotein complexes.
Time‐Resolved Resonance Raman Spectroscopy of Photochemical Reactive Intermediates: Radical Cationof Fluorene and Triplet State of Fluorene, Dibenzofuran and Dibenzothiophen
Authors: Buntinx G. , Poizat O.
Published: September 2007

The time‐resolved Raman spectra of the first triplet state–in resonance with the Tn ← T1 absorption at
370 nm–and of the radical cation transient–in resonance with the absorptions at 370 nm and
in the 560‐600 nm range‐are reported for fluorene. The triplet state Raman spectra of dibenzofuran and
dibenzothiophen are also given. The vibrational assignments, resonance Raman activity and intensity
enhancement effects are studied. On this basis, the structures and electronic configurations of the triplet
state and radical cation transients and the nature of the resonant Tn ← T1 and

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transitions are
discussed. It turns out from this investigation that the title molecules present close analogies with
biphenyl. The insertion of a methylene group or a heteroatom does not disturb markedly the electronic
properties of the ground state, the first triplet state and the radical cation transient of biphenyl.
Reactive Bimolecular Collisions Studied With Combined Pulsed Lasersand Pulsed, Crossed, Supersonic Molecular Beams
Authors: Costes M. , Naulin C. , Dorthe G. , Moudden Z.
Published: September 2007

Pulsed, supersonic molecular beams and pulsed lasers are particularly well matched tools when combined
in molecular reaction dynamics studies. Salient features of an experiment using two pulsed molecular
beam sources, a pulsed ultra‐violet laser for creating reactive atoms by laser ablation and a pulsed dye
laser for performing laser‐induced fluorescence detection of the products are described. Differences with
steady‐state molecular beam experiments are outlined with respect to the following points: facility of
inverting the data, possibility of obtaining high signal‐to‐background ratios and wide ranges of collision
energy. These points are illustrated with some results concerning the reactions:

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and

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Dynamics of Vibrational Relaxation of Multiphoton Excited SF6 Molecules inGaseous Mixtures Containing Ozone and Inert Gases (He, Ar, Kr)
Authors: Timofeev V. V. , Lunin B. S. , Mordkovich N. Yu , Zhitnev Yu. N.
Published: September 2007

SF6 at pressure of 0.6 Torr in gas mixtures with ozone (0 ÷ 5 Torr) and inert gases: He, Ar, Kr (0 ÷ 5 Torr) was vibrationally excited with and IR pulsed radiation of CO2 TEA laser at 10P20 laser line
(F= 0.6 J/cm2). The vibrational energy transfer from multiphoton excited (MPE) molecules SF6 to the components of gaseous mixture was probed by UV absorption of ozone at λ = 253.6 nm band. The relaxation
process of MPE molecules SF6 was proposed to occur through parallel V‐V′ and V‐T collisional channels.
Based on the kinetic model, collisional rate constants were determined from the time evolution of UV
absorption data after laser shot. The obtained values of relaxation rate constants are:

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The observed decay of IR fluorescence from MPE SF6 molecules at λ = 6.3 μm wave number in SF6‐Kr
gas mixtures had an exponential time profile with the constant characteristic relaxation time (V‐T). The
rate of IR fluorescence cluenching allowed us to find an effective V‐T relaxation rate constants for
collisional partners:

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.

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.
Ê‐μ‐V Correlation In One‐Colour Photolysis/Ionization Of Tert‐Butyl Nitrite
Authors: Marcus P. , Platzner I. , Bar I. , Rosenwaks S.
Published: September 2007

An anisotropic spatial velocity distribution was observed for NO+ produced following one‐color
photolysis/ionization of tert‐butyl nitrite (TBN) by a pulsed polarized laser at 266, 355 and 532 nm in a
time‐of‐flight mass spectrometer. The dependence of the NO+ fragment mass peak profile on the
wavelength and on the polarization was monitored. The most striking feature is the varying fragment peak
splitting obtained under the same experimental conditions by changing the laser polarization direction.
This phenomenon is a result of the vector correlation between the laser polarization,Ê, at a given wavelength,
the electronic transition dipole moment of TBN,μ, and the direction of the NO fragment velocity,
v. The dynamics of the photodissociation process and, in particular, its directional properties are
discussed in view of these results.
Lifetime Measurements Of CaCl∗(A2Π) In A Molecular Beam
Authors: Verdasco E. , Rabanos V. Sáez , Telle H. H. , Urena A. GonzáLez
Published: September 2007

An effusive thermal molecular beam of CaCI was produced vapourizing a mixture of Ca and CaCI2 within
a crucible with subsequent expansion into vacuum. Lifetimes of

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in its two lowest vibrational
levels were measured under collision‐free conditions using laser‐induced fluorescence, and values around
33 ns are found; these are discussed with respect to other available data.
Some Novel Infrared Laser Dyes of Superior Photostability Tunable From 1.30 to 1.52 µm
Authors: Luo Weimei , Zhu Zhenghua , Yao Yuguang , Ye Lin , Yuan Xiangchun
Published: September 2007

Three new heptamethine pyrylium dyes containing a disubstituted amino group on the meso position in
their bridged chain were investigated. The solutions of the dyes in 1,2‐dichloroethane (DCE) of
concentration ca. 10-3 M act as laser dyes transversely pumped by a Q‐switched Nd:YAG laser as a
pumping source. 5.6 to 9.6% of the pump energy was converted to an intense infrared pulse with
frequencies between 6580 cm-1 (1.52 µm) and 7690 cm-1 (1.30/µm). The relation between lasing efficiency and dye concentration was also studied. These dyes show a remarkable photostability upon 1.06
µm laser excitation and excellent storage stability without degassing.
Photophysical Properties of The DCM and DFSBO Styryl DyesConsequence for Their Laser Properties
Authors: Mialocq Jean-Claude , Meyer Martine
Published: September 2007

The two styryl dyes, 4‐dicyanomethylene‐2‐methyl‐6‐P‐dimethylaminostyryl‐4H‐pyran (DCM) and 7‐
dimethylamino‐3‐(p‐formylstyryl)‐l, 4‐benzoxazin‐2‐one (DFSBO) exhibit similar solvent‐induced shifts
of their absorption and emission spectra related to a large intramolecular charge transfer (ICT) in the first
singlet excited state. From the Stokes shift values (vA − vF) and a vectorial analysis of their ground state
dipole moment (μg= 6.1 D for DCM and 5.8 D for DFSBO), and using the Lippert‐Mataga theory, we
have estimated the dipole moments of their fluorescent excited states S1 (μe = 26.3 D for DCM and 27.6 D for DFSBO). Intersystem crossing to the triplet state is totally inefficient in DCM but significant in
DFSBO. Moreover the absorption of the DFSBO triplet is quite large in the emission band (600–650 nm),
which makes of DFSBO a poor laser dye. Although DCM trans‐cis photoisomerization can be quite
efficient in non polar solvents (chloroform, tetrahydrofuran), DFSBO does not photoisomerize probably
due to steric hindrance and to the S1 character which should be more "benzoxazinone" than ethylenic.
DFSBO is also shown to exhibit rotamerism.
Lasers and Photopolymers
Authors: Carre C. , Decker C. , Fouassier J. P. , Lougnot D. J.
Published: September 2007

A general outline of new applications of lasers in polymer photochemistry is given. The fields covered
include the kinetic and mechanistic study of various elementary processes (in solution model compounds)
by laser spectroscopies and the extension of this approach to practical systems (solids or in polymerization
samples, thin films) by holographic techniques or real‐time infrared spectroscopy. Stress is laid on the
great importance of laser techniques in understanding the fundamental aspects of the processes involved
in polymer photochemistry.
Angular Selection of Products by Use of Saturated‐Absorption Techniques in the Cs(7P)+H2→CsH+H​ Reaction
Authors: L′Hermite J. -M. , Rahmat G. , Vetter R.
Published: September 2007

The

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reaction is studied in a crossed‐beam experiment with laser‐induced
fluorescence detection of CsH products. The usual flux

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which is delivered by the C.W.
tunable dye laser used in the experiment is enough to saturate the absorption by CsH products. Then, by
crossing twice the laser beam through the collision volume (counterpropagating beams), one realizes the
conditions of saturated‐absorption experiments: when the laser frequency is tuned to a resonance
frequency of CsH products, a defect to absorption occurs for these products which scatter in the collision
plane and a "saturation dip" appears at the center of the corresponding fluorescence profile. Application
of this technique to crossed‐beam experiments can lead to the selection of product molecules which scatter
in any definite plane. A different geometry of the laser beams (bent beams) is proposed to select molecules
which scatter in any definite direction: it could be applied to detect an asymmetry in the scattering of the
products with respect to the collision axis, when a particular preparation of the reagents is realized.
Modeling the Vibrational Relaxation of Polyatomic Molecules. The Methylfluoride Case Study
Authors: Tosa V. , Bruzzese R. , de Lisio C. , Solimeno S.
Published: September 2007

We present in this paper a theoretical analysis of the vibrational translational (V‐T) relaxation process in
CH3F, carried out by using a numerical model based on rate equations. In particular, we have analysed the
dependence of the V‐T relaxation time on the average vibrational energy absorbed per molecule. We
have also investigated the influence of the dependence of the rate constants used in the model, on the gas
translational temperature. The results of the model clearly outline the strongly nonlinear character of the
V‐T relaxation process in CH3F, a situation commonly observed in other important polyatomic molecules
of intermediate size each as SF6, freons, and related methylhalides.
Laser Induced Fluorescence
Authors: Bras N.
Published: September 2007

Laser induced fluorescence (LIF) has become a common detector of atoms and molecules allowing to
determine their internal state distributions. In this paper we mention the advantages of both kinds of
lasers, cw or pulsed. We review some aspects of the LIF process, such as saturation or polarization effects,
which could alter the results if they were not taken into account. We also indicate how LIF can be used to
measure relaxation times and thus rate constants of the relaxation processes: some experimental results
obtained in our laboratory illustrate these points.
Electronic Spectra of 1‐Phenylethylamine and its Derivatives in Supersonic Jets
Authors: Yamamoto Seiji , Niwa Taeko , Ito Mitsuo
Published: September 2007

The S1 ← S0 fluorescence excitation spectra and dispersed fluorescence spectra of jet‐cooled (+)‐, (‐)‐
and (±)‐1‐phenylethylamine and their derivatives (amides) have been observed. The 0‐0 band of the
amine locates at 37,641 cm‐1. The amides which were synthesized from (+)‐amine or (‐)‐amine with
(+)‐tartaric acid are diastereomers. It was found that the two diastereomers give the identical spectra with
the 0‐0 band at 34,757 cm-1. No difference in the spectrum indicates that the excitation is localized in the
phenyl group which is far from the asymmetric carbon causing diastereoism. It was also found that
1‐phenylethylamine has a fast nonradiative relaxation process in the Sstate, but such a process is removed
by the formation of the amide.
Solvation Dynamics Studied by Picosecond Fluorescence: Microscopic Reorientation and Longitudinal Relaxation of the Solvent
Authors: Declémy A. , Rulliére C. , Kottis Ph.
Published: September 2007

The dynamics of the Time‐Dependent Fluorescence Shift (TDFS) of a rigid polar excited probe dissolved
in alcohol solvents at different temperatures have been studied by picosecond time‐resolved spectroscopy.
The results are compared to previously published results on well characterized polar systems. These
results show that solvation dynamics in such systems are strongly scaled by the microscopic (singleparticle)
reorientation time τM of the solvent molecules and/or by the (macroscopic) longitudinal
relaxation time τL of the solvent. The key point governing this scaling is the relative interaction between
the solvent molecules and the probe compared to the interaction between the solvent molecules. It is also
shown that specific interactions, such as hydrogen bonded‐complex formation, may play an important
role.
Infrared Laser Photochemistry of Trans‐1, 2‐Dichloroethylene. Evidence For A CI Atom Chain Reaction
Authors: Guckert Joseph R. , Carr Robert W.
Published: September 2007

The TEA‐CO2 laser induced reaction of trans‐l,2‐dichloroethylene (TDCE) was investigated at 925
cm-1. The laser radiation was focused to yield beam waist fluences of approximately 125 J cm-2. The
major reaction product was cis‐1, 2‐dichloroethylene (CDCE), with a few per cent of chloroacetylene, and
minor amounts of acetylene, dichloroacetylene, chloroethylene and an unidentified C4 compound also
being formed. The reaction of pure TDCE was studied as a function of number of laser pulses and total
pressure (0.02 to 5 torr). Some experiments were also done with added ethane (20%) and propane (2%).
Evidence was obtained that the formation of the cis isomer occurs via two mechanisms, (1) a unimolecular
isomerization, and (2) a CI atom chain reaction. The results are consistent with laser induced decomposition
of TDCE occurring through the three lowest energy channels: unimolecular structural isomerization
(57.4 kcal/mol); molecular HCI elimination (69 kcal/mol); and C‐CI bond scission (89 kcal/mol).
Pulsed Co2‐Laser Excitation of 03/02 Mixtures at Pressures From 0.16 to 1.20 Bar
Authors: Raffel B. , Wolfrum J.
Published: September 2007

An investigation is presented of the transient vibrational excitation of O3 in the collision dominated
regime initiated by pulsed CO2‐laser radiation. IR‐UV‐double resonance experiments and measurements
of the absorbance for the CO2‐laser lines 9P18, 20, and 22 were carried out. Mixtures of O3 (p=17 mbar)
with 02 were investigated at pressures of 160 mbar ≤Pmixt ≤ 1200 mbar and laser fluences of 0.10 J/cm2 ≤ Fin <  2 J/cm2
. The results are interpreted by numerical simulations in terms of a comprehensive
excitation/relaxation model based upon SSH‐theory. Concerning the evolution of the excitation, simulated
transients of the UV‐absorbance compare well with the corresponding observed signals. The
saturation of the absorbing O3‐transitions is demonstrated by the measured fluence dependence of the
absorption coefficient at the laser wavelengths. The extent of the 03‐excitation can be deduced according
to the model from the maximum vibrational temperature Tm reached in the v1‐ and v3‐oscillators. Tm
accessible via the UV‐transients and also via the absorbed laser energy in the case of slow relaxation at 160
160​mbar ≤ Pmixt ≤ 340 mbar. In this range both techniques result in the same values for

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. The experimental
and the corresponding simulated

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depend exponentially on the laser fluence
provided Tm > 400​K being also confirmed up to Pmixt = 1200 mbar by the observed UV‐transients.