Biological effects of helium-neon (HeNe) laser irradiation on acrosome reaction in bull sperm cells

The purpose of this study was to determine the effect of He---Ne laser irradiation (632.8 nm, 10 mW) on the induction of acrosome reaction and mortality in bull sperm cells in comparison with two important capacitation agents; calcium and heparin. Frozen-thawed bull sperm cells were washed in percoll gradient and suspended at a concentration of 1 × 10⁶ ml⁻¹ in sp-TALP medium, capacitated in the presence of 2 mM CaCl₂, 10 μg ml⁻¹ heparin, or irradiated at fluences from 2 to 16 J cm⁻², and incubated for 0, 30, 60 and 90 minutes. At the end of the incubation period, the percentage of sperm that were acrosome-reacted and dead was determined. The results obtained indicated that laser irradiation at all fluences produced a significant increase (p < 0.001) in the percentage of sperm cells that were acrosome reacted, and a significant decrease (p < 0.001) in the percentage of dead sperm at 90 minutes of incubation in comparison to other capacitation agents and the control group. The percentage of sperm cells with acrosome reaction was increased with increasing fluences of laser irradiation and time of incubation. It is conclude that the application of He---Ne laser irradiation at fluences from 2 to 16 J cm⁻² induced the acrosome reaction and decreased the sperm mortality percentage in vitro of bull sperm cells.     

Comparison of the effects of visible femtosecond laser pulses and continuous wave laser radiation of low average intensity on the clonogenicity of Escherichia coli.

To evaluate the contribution of local pulsed heating of light-absorbing microregions to biochemical activity, irradiation of Escherichia coli was carried out using femtosecond laser pulses (λ = 620 nm, τ_p=3 × 10⁻¹³ s, f_p = 0.5 Hz, E_p = 1.1 × 10⁻³J cm⁻², I_av = 5.5 × 10⁻⁴ W cm⁻², I_p = 10⁹ W cm⁻²) and continuous wave (CW) laser radiation (λ = 632.8 nm, I = 1.3 W cm⁻²). The irradiation dose required to produce a similar biological effect (a 160%–190% increase in the clonogenic activity of the irradiated cells compared with the non-irradiated controls) is a factor of about 10³ lower for pulsed radiation than for CW radiation (3.3 × 10⁻¹ and 7.8 × 10² J cm⁻² respectively). The minimum size of the microregions transiently heated on irradiation with femtosecond laser pulses is estimated to be about 10 Å, which corresponds to the size of the chromophores of hypothetical primary photoacceptors—respiratory chain components.     

Si (IV)-methoxyethylene-glycol-naphthalocyanine: synthesis and pharmacokinetic and photosensitizing properties in different tumour models

A Si(IV)-naphthalocyanine bearing two methoxyethylenglycol axial ligands to the centrally coordinated metal ion (SiNc) was prepared by chemical synthesis and assayed for the phototherapeutic activity after administration in a Cremophor formulation to C57BI/6 mice bearing a subcutaneously transplanted Lewis lung carcinoma or B16 pigmented melanoma. Pharmacokinetic studies indicate that the maximal accumulation in the tumour occurs at 24 h after intraperitoneal injection of 0.5 mg kg⁻¹ of SiNc, although the naphthalocyanine concentration in the Lewis lung carcinoma (0.70 μg g⁻¹) is significantly larger than that in the B16 pigmented melanoma (0.15 μg g⁻¹). This result in a higher selectivity of tumour targeting in the case of the lung carcinoma. Photodynamic therapy (782 nm, 370 mW cm⁻², 360 J cm⁻²) at 24 h after SiNc injection causes an efficient tumour response for Lewis lung carcinoma (50% lower tumour diameter on day 19 post-treatment as compared to untreated controls) while the pigmented melanoma shows only a minor response regarding the rate of tumour growth.     

HepG2 human hepatocarcinoma cells: an experimental model for photosensitization by endogenous porphyrins

Endogenous protoporphyurin IX (PpIX) synthesis after δ-aminolaevulinic acid (ALA) administration occurs in cancer cells in vivo; PpIX, which has a short half-life, may thus constitute a good alternative to haematoporphyrin derivative (HPD) (or Photofrin). This study assesses the ability of the human hepatocarcinoma cell line HepG2 to synthesize PpIX in vitro from exogenous ALA, and compares ALA-induced toxicity and phototoxicity with the photodynamic therapy (PDT) effects of HPD on this cell line.

ALA induced a dose-dependent dark toxicity, with 79% and 66% cell survival for 50 and 100 μg ml⁻¹ ALA respectively after 3 h incubation; the same treatment, followed by laser irradiation (λ = 632 nm, 25 J cm⁻²), induced a dose-dependent phototoxicity, with 54% and 19% cell survival 24 h after PDT. Whatever the incubation time with ALA, a 3 h delay before light exposure was found to be optimal to reach a maximum phototoxicity.

HPD induced a slight dose-dependent toxicity in HepG2 cells and a dose- and time-dependent phototoxicity ten times greater than that of ALA-PpIX PDT. After 3 h incubation of 2.5 and 5 μg ml⁻¹ HPD, followed by laser irradiation (λ = 632 nm, 25 J cm⁻²), cell survival was 59% and 24% respectively at 24 h.

Photoproducts induced by light irradiation of porphyrins absorb light in the red spectral region at longer wavelengths than the original porphyrins. The possible enhancement of PDT effects after HepG2 cell incubation with ALA or HPD was investigated by irradiating cells successively with red light (λ = 632 nm) and light (λ = 650 nm). The total fluence was kept constant at 25 J cm⁻². For both HPD and ALA-PpIX PDT, phototoxicity was lower when cells were irradiated for increased periods with λ = 650 nm light than with λ = 632 nm light alone. This suggests that any photoproducts involved either have a short life or are poorly photoreactive.

Not all cell lines can synthesize PpIX after ALA incubation. HepG2 cells, which can synthesize enzymes and precursors of endogenous porphyrin synthesis, represent a good in vitro model for experiments using ALA-PpIX PDT. In addition, ALA-PpIX PDT may represent a new, specific treatment for hepatocarcinomas.     

Energetic distribution of the electrons from a 200 keV beam in polyurethane layers : EGS4 calculation and FTIR analysis

The aim of this study is to characterize the chemical transformation of a polymer resulting from irradiation by a 200 keV electron beam. Thermoplastic PU polyetherurethane material was used and irradiation was performed with applied electron fluences in the range of 10¹⁴–10¹⁷ electron cm⁻² at 77 K.

The chemical changes have been observed by FTIR analysis of irradiated layers. A NH bond evolution study has allowed us to follow polymer degradation versus depth and fluence. The results have been compared to a simulation of electronic energy loss and to the energy spectrum of the generated electrons in the polymer using EGS4 code.     

Infrared studies of chromones—I Carbonyl and hydroxyl regions

Quantitative IR solution data in carbon tetrachloride and chloroform are recorded for the CO and OH regions of 31 chromones. In the 1580–1700 cm⁻¹ region, 5-hydroxychromones show three main maxima, the two of highest frequency, at 1663 ± 3 cm⁻¹ and 1630 ± 5 cm⁻¹ in CCl₄ (1661 ± 2 cm⁻¹ and 1627 ± 5 cm⁻¹ in CHCl₃), being sufficiently intense as to possess high CO character. Typically, 5-alkoxychromones exhibit two intense maxima in this region, 1663 ± 3 cm⁻¹ and 1613 ± 7 cm⁻¹ in CCl₄ (1657 ± 2 cm⁻¹ and 1608 ± 12 cm⁻¹ in CHCl₃). Diagnostically useful changes in contour and principal peak positions can be seen for substituted and annellated 5-hydroxychromones. In the 2500–3650 cm⁻¹ region, the stretching frequencies of OH groups at the most commonly encountered positions (C-5, C-7, and 2-CH₂OH) in natural chromones, are identified.     

The rovibrational analysis of the high-resolution IR spectrum of CD2HF below 1200 cm: an interacting tetrad of vibrational levels

The spectrum of CD₂HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm⁻¹ fwhm) between 800 and 1200 cm⁻¹ covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν₉: 912.2028 cm⁻¹, ν₆:964.4994 cm⁻¹, ν₅: 1050.5104 cm⁻¹, ν₄: 1093.8632 cm⁻¹) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν₉ and ν₆ (ξ_a= 1.069 cm⁻¹, ξ_c= −0.3535 cm⁻¹) and between ν₅ and ν₄ (ξ_b= −0.80606 cm⁻¹). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level.     

Targeting of the tumor microcirculation by photodynamic therapy with a synthetic porphycene

9-acetoxy-2,7,12,17-tetrakis-(β-methoxyethyl)-porphycene (ATMPn) is a chemically pure substance with fast pharmacokinetics and superior photodynamic properties in vitro as compared to Photofrin®. In this study the pharmacokinetics, photodynamic efficacy and tissue localization of ATMPn were investigated in vivo.

Amelanotic melanomas (A-Mel-3) were implanted in dorsal skin fold chambers fitted to Syrian Golden hamsters. Fluorescence kinetics of ATMPn (1.4 μmol kg⁻¹ b.w.i.v; n = 8) were monitored by intravital microscopy. Quantitative measurements of fluorescence intensity were carried out by digital image analysis. For tumor growth studies 1.4 μmol kg⁻¹ was injected 24 h (n = 3), 3 h (n = 3), 1 min (n = 6) and 2.8 μmol kg⁻¹ 1 min (n = 6) before PDT (Laser (630 nm) or lamp (600–750 nm), 100 mW cm⁻², 100 J cm⁻²). Tumor volume was measured for 28 d. Solid tumors (n = 3) were excised 1 min after injection of ATMPn (2.8 μmol kg⁻¹) and cryostat sections (20 mm) were analyzed by confocal laser scanning microscopy (CLSM) for tissue localization of the dye.

Maximal fluorescence (mean ± S.E.) arose in the tumor (94 ± 7%) and surrounding host tissue (67 ± 5%) 30 s post injection followed by a rapid decrease. Hardly any fluorescence was detectable 12 h after administration. Only PDT 1 min after injection of ATMPn was effective yielding 3/6 complete remissions (2.8 mmol kg⁻¹, laser) and 6/6 complete remissions (2.8 μmol kg⁻¹, lamp), respectively. One minute after injection the dye is primarily localized in the vascular wall of normal and tumor vessels as shown by CLSM.

PDT at a time, when the dye is localized primarily in the tumor microcirculation, exhibits the best tumor killing effects showing that vascular targeting is effective in treating solid malignant tumors. ATMPn in liposomes makes administration and light irradiation in one session possible due to its fast pharmacokinetics. Thus, using ATMPn as a photosensitizer may provide more flexibility to perform PDT after surgical exploration and debulking as adjuvant therapy.     

Proton transfer between hydrogen halides and dimethylether in nitrogen matrices. An example of infrared-induced transfer

The infrared absorption of mixtures of dimethyl ether and hydrogen halide (HX) in nitrogen at 13 K display relatively narrow bands in the range 650–800 cm⁻¹ with an isotopic ratio ν_H/ν_D larger than 1.4 and weakly halogen dependent; these features are assigned to the antisymmetric O…H…O stretching within the [(CH₃)₂ O…H…O(CH₃)₂]⁺X⁻ ion pair. With HI—ether mixtures, the intensity of the 660 cm⁻¹ band decreases under infrared irradiation of the matrix, which might be due to the transfer of the proton back to the I⁻ anion.     

The beryllium dimer potential

The convergence of ab initio calculations of the beryllium dimer potential is examined with several basis sets orders of perturbation theory. When the atomic pair natural orbital basis set calculations are extrapolated to the complete basis set and full CI limits, the calculated parameters: R_e=2.447 Å, D_e=827 cm⁻¹, ν₀₁=212.7 cm⁻¹, ν₁₂=167.2 cm⁻¹, ν₂₃=121.5 cm⁻¹ and ν₃₄=77.7 cm⁻¹ are in good agreement with the experimental parameters: R_e=2.45 Å, D_e=839±10 cm⁻¹, ν₀₁=223.2 cm⁻¹, ν₁₂=169.7 cm⁻¹, ν₂₃=122.5 cm⁻¹, and ν₃₄=79 cm⁻¹.     

Carbon—hydrogen stretching vibrations in fluorocyclohexanes

For perfluorocyclohexane derivatives in which not more than one fluorine at each carbon atom is replaced by a hydrogen atom, it is established that C---H groups with an axial hydrogen show infra-red absorption at 2980 cm⁻¹ and with equatorial hydrogen at 2974 cm⁻¹. With 1H/2H-, 1H:2H/- and 1H:3H/-decafluorocyclohexane the frequencies are reduced somewhat. When the C---H groups are adjacent to a double bond the absorption is at 2961 cm⁻¹, while olefinic C---H groups absorb near 3095 cm⁻¹ in the fluorocarbon series. The C---H absorption is at 3102 cm⁻¹ in pentafluorobenzene.     

Vibrational overtone activation of methylcyclopropene

The vibrational overtone spectrum of methylcyclopropene in the region of the 6-0 and 5-0 C---H stretching transitions is reported. Transitions corresponding to the methyl, methylenic and vinyl C---H stretches are assigned. From the Birge-Sponer plots the anharmonicities and mechanical frequencies for the methyl in-plane and out-of-plane C---H stretches are −67.0 and 3118.0 cm⁻¹ and −64.0 and 3071.0 cm⁻¹, respectively. The corresponding values for the methylenic C---H stretches are −60.5 and 3030.7 cm⁻¹. Photolysis at 17093 cm⁻¹ (585 nm) yields two stable products which were identified by gas chromatography. Approximately 60% of the total yield was 2-butyne. A specific rate constant of 1.66×10⁸ s⁻¹ results from the Stern-Volmer analysis of the product yield of 2-butyne.     

An ab initio close-coupling calculation of the lower vibrational energies of the HCl dimer

We have previously determined an analytical ab initio six-dimensional potential energy surface for the HCl dimer, and in the present paper we use this potential, with the HCl bond lengths held fixed, in a full (four-dimensional) close-coupling calculation to determine the energies of the lowest 24 vibrational states. These vibrational states involve the intermolecular stretch ν₄, the trans-bend tunneling vibration ν₅, and the torsion ν₆. The highest of the 24 levels is the (ν₄ν₅ν₆)=(111) state, for which we calculate an energy of 200 cm⁻¹ above the (000) state. As well as determining tunneling energies up to 5ν₅=183 cm⁻¹, we determine ν₄=49 cm⁻¹, 2ν₄=93 cm⁻¹, 3ν₄=134 cm⁻¹, 4ν₄=172 cm⁻¹, ν₆=137 cm⁻¹ and ν₄+ν₆=178 cm⁻¹, together with tunneling energies in all these states. Making allowance for the HCl stretching zero-point energy we determine the dissociation energy D₀ as 390 cm⁻¹ on this analytical surface. We determine that below 300 cm⁻¹ there are 72 vibrational (J=K=0) states, and below dissociation there are 162 vibrational (J=K=0) states, for this potential surface.     

The effect of hydrogen bonding interactions between 2-[4-(dimethylamino)phenyl]-3-hydroxy-4H-chromene-4-one in the ground and excited states and dimethylsulfoxide or methanol on electronic absorption and emission transitions

The surface state of optically pure polydisperse TiO₂ (anatase and rutile) was determined by infra-red (IR) spectroscopy analysis in the temperature range of 100–453 K. Anatase A300 spectrum, contrary to rutile R300 one, has a broad three-component absorption band with peaks at 1048, 1137 and 1222 cm⁻¹ in the spectral range of δ(Ti–O–H) deformation vibrations. For rutile R300 we observed a very weak band at 1047 cm⁻¹, and for the thermal treated rutile R900 these bands were not appeared at all. The analysis of temperature dependencies for the mentioned absorption bands revealed the spectral shift of 1222 cm⁻¹ band towards the high frequencies, when the temperature increased, but the spectral parameters of 1137 and 1048 cm⁻¹ bands remained the same. The temperature of 1222 cm⁻¹ band maximum shift was 373–393 K and correlated with DSC data. Obtained results allowed to assign 1222 cm⁻¹ band to the deformation vibrations of OH-groups, bounded to the surface adsorbed water molecules by weak hydrogen bonds (5 kcal/mol). During the temperature growth these molecules desorbed, which also resulted in the intensity decreasing of stretching OH-groups vibration IR-bands at 3420 cm⁻¹. The destruction and desorption of surface water complexes led to Ti–O–H bond strengthening. IR bands at 1137 and 1048 cm⁻¹ were attributed to the stronger bounded adsorbed water molecules, which are also characterized with stretching OH-groups vibration bands at 3200 cm⁻¹. These surface structure were additionally stabilized by hydrogen bonds with the neighbouring TiO₂ lattice anions and other OH-groups, and desorbed at higher temperatures.     

On the vibrational spectra and conformational stability of 1,1-dimethylhydrazine from temperature dependent FT-IR spectra of krypton solutions and ab initio calculations

Variable temperature (−105 to −150 °C) studies of the infrared spectra (3500–400 cm⁻¹) of 1,1-dimethylhydrazine, (CH₃)₂NNH₂, in liquid krypton have been carried out. No convincing spectral evidence could be found for the trans conformer which is expected to be at least 600 cm⁻¹ less stable than the gauche form. The structural parameters, dipole moments, conformational stability, vibrational frequencies, and infrared and Raman intensities have been predicted from MP2/6-31G(d) ab initio calculations. The predicted infrared and Raman spectra are compared to the experimental ones. The adjusted r₀ parameters from MP2/6-311+G(d,p) calculations are compared to those reported from an electron diffraction study. The energy differences between the gauche and trans conformers have been obtained from MP2 ab initio calculations as well as from density functional theory by the B3LYP method calculations from a variety of basis sets. All of these calculations indicate an energy difference of 650–900 cm⁻¹ with the B3LYP calculations predicted the larger values. The potential function governing the conformational interchange has been predicting from both types of calculations and comparisons have been made. The barrier to internal rotation by the independent rotor model of the inner methyl group is predicted to have a value of 1812 cm⁻¹ and that of the outer one of 1662 cm⁻¹ from ab initio MP2/6-31G(d) calculations. These values agree well with the experimentally determined values of 1852±16 and 1558±12 cm⁻¹, respectively, from a fit of the torsional transitions with the coupled rotor model. For the coupled rotor model the predicted V′₃₃ (sin 3τ₀ sin 3τ₁ term) value which ranged from 190 to 232 cm⁻¹ is in reasonable agreement with the experimental value of 268±3 cm⁻¹ but the predicted V₃₃ (cos 3τ₀ cos 3τ₁ term) value of −73 to −139 cm⁻¹ is 25% smaller and of the opposite sign of the experimental value of 333±22 cm⁻¹. These theoretical and spectroscopy results are compared to similar quantities of some corresponding molecules.     

Photodissociation spectroscopy of Mg—Ar

Mg⁺—Ar ion—molecule complexes are produced in a pulsed supersonic nozzle cluster source. The complexes are mass selected and studied with laser photodissociation spectroscopy in a reflectron time-of-flight mass spectrometer system. An electronic transition assigned as X ²Σ⁺ → ²Π is observed with an origin at 31387 cm⁻¹ (vac) for ²⁴Mg⁺—Ar. The ²⁴Mg⁺—Ar spectrum is characterized by a 15 member progression with a frequency (ω′_e) of 272 cm⁻¹. An extrapolation of this progression fixes the excited state dissociation energy (D′_o) at 5552 cm⁻¹. The corresponding ground-state value (D″_o) is 1270 cm⁻¹ (3.6 kcal/mol). The ²Π _, spin—orbit splitting is 76 cm⁻.     

Matrix-isolation spectroscopy of Pb2

Fluorescence and Raman scattering were observed from Pb₂ isolated in neon and argon matrices. Two new excited states were observed by two-photon stepwise excitations, which involve low-lying electronic states of Pb₂. Most spectroscopic constants of the states observed could be given and complement previous results. Two resonance Raman progressions with ω_c = 112.5 and 123.1 cm⁻¹ and a single Raman signal at 80 cm⁻¹ were observed in argon matrices. The ω_c = 123.1 cm⁻¹ Raman signal which had recently been assigned to a larger Pb cluster was shown to arise from Raman scattering within the electronically excited A state of Pb₂ at 5500 cm⁻¹.     

Far infrared spectra, conformational equilibria, vibrational assignments, ab initio calculations and structural parameters for 2-bromoethanol

The far infrared spectrum from 370 to 50 cm⁻¹ of gaseous 2-bromoethanol, BrCH₂CH₂OH, was recorded at a resolution of 0.10 cm⁻¹. The fundamental O–H torsion of the more stable gauche (Gg′) conformer, where the capital G refers to internal rotation around the C–C bond and the lower case g to the internal rotation around the C–O bond, was observed as a series of Q-branch transitions beginning at 340 cm⁻¹. The corresponding O–H torsional modes were observed for two of the other high energy conformers, Tg (285 cm⁻¹) and Tt (234 cm⁻¹). The heavy atom asymmetric torsion (rotation around C–C bond) for the Gg′ conformer has been observed at 140 cm⁻¹. Variable temperature (−63 to −100°C) studies of the infrared spectra (4000–400 cm⁻¹) of the sample dissolved in liquid xenon have been recorded. From these data the enthalpy differences have been determined to be 411±40 cm⁻¹ (4.92±0.48 kJ/mol) for the Gg′/Tt and 315±40 cm⁻¹ (3.76±0.48 kJ/mol) for the Gg′/Tg, with the Gg′ conformer the most stable form. Additionally, the infrared spectrum of the gas, and Raman spectrum of the liquid phase are reported. The structural parameters, conformational stabilities, barriers to internal rotation and fundamental frequencies have been obtained from ab initio calculations utilizing different basis sets at the restricted Hartree–Fock or with full electron correlation by the perturbation method to second order. The theoretical results are compared to the experimental results when appropriate. Combining the ab initio calculations with the microwave rotational constants, r₀ adjusted parameters have been obtained for the three 2-haloethanols (F, Cl and Br) for the Gg′ conformers.     

Vibrational spectrum of I(H2O)

The infrared spectrum of the ionic cluster I⁻(H₂O) was recorded from 3170 to 3800 cm⁻¹ by vibrational predissociation spectroscopy. A strong multiplet observed at 3415 cm⁻¹ and a narrow band at 3710 cm⁻¹ were assigned as a hydrogen-bonded OH stretch and free OH stretch respectively, indicating that H₂O forms a single hydrogen bond with the iodide anion. Ab initio vibrational frequencies and intensities were computed at the second-order Møller-Plesset (MP2) level for the minimum energy configuration, a nearly linear hydrogen-bonded isomer, and for a low-lying saddlepoint, a symmetric C_2v bridged isomer. The spectrum predicted for the hydrogen-bonded isomer agreed well with experiment.     

In Vivo Fluence Rate Effect in Photodynamic Therapy of Early Cancers with Tetra(m-hydroxyphenyl)chlorin

Abstract— Several parameters affect clinical trials in photodynamic therapy and influence the therapeutic outcome. Beside drug dose, light dose, drug-light interval and other variables, the fluence rate is a parameter that can influence the therapeutic results. In this study we have evaluated the fluence rate effect with a second-generation photosensitizer, tetra( m -hydroxyphenyl)chlorin (mTHPC) using a 7,12-dimethylbenz(a)anthracene induced early squamous cell carcinoma of the Syrian hamster cheek pouch as a tumor model. Following injection of 0.5 mg/kg of mTHPC, irradiation tests were performed at two drug-light intervals, 4 and 8 days. Wavelength and light dose were adapted from those applied routinely in clinical trials. Irradiations at 652 nm were carried out with fluences ranging from 8 to 20 J/cm² delivered at fluence rates of 15 and 150 mW/cm². Similar tests were also performed at 514 nm with a fluence of 80 J/cm² delivered at fluence rates ranging from 25 to 125 mW/cm². At both wavelengths and drug-light intervals for a given fluence, the higher fluence rates resulted in less tissue damage in tumor and healthy mucosae. However, the lower fluence rates yielded slightly less therapeutic selectivity. This study confirms that the fluence rate is of major importance in clinical PDT.