Bibliothek

Notizen: Abstract: The effect of treatment with acute fluoxetine, a serotonin reuptake inhibitor, on the rate of serotonin synthesis in the rat brain was studied through autoradiography following intravenous administration of α-methyl-l-[3H]tryptophan. The rate of serotonin synthesis in fluoxetine-treated rats was compared with the rate measured in sham-treated rats (saline injection). Results showed a significant increase in the rate of synthesis in the majority of cerebral structures examined. The greatest increase (given as a percentage of rates in control animals) in the rate of serotonin synthesis was observed in the substantia nigra compacta (344%), hippocampus-CA3 (337%), dorsal hippocampus (283%), and caudate-putamen (232%). Fluoxetine had a less significant effect on the rate of synthesis in the pineal body (44%). Data suggest that acute fluoxetine treatment (30 mg/kg, i.p.) enhances the rate of serotonin synthesis in all the structures of rat brain examined in this work.

Notizen: We present a new method to evaluate the photo-oxidative activity of sunscreening agents based on the photodynamic oxidation of uric acid. Uric acid was selected as the oxidant probe for its high reactivity to singlet oxygen and oxygen radicals, high sensitivity of detection using electrochemical (EC) techniques, low light absorptivity and high photochemical stability in the UVA/B region of interest, and stability to autoxidation. The method is demonstrated by the photodynamic oxidation of uric acid on co-irradiation with Rose Bengal, a highly efficient photosensitizing dye for the production of singlet oxygen (1O2). Using this assay we found that the relative photodynamic oxidation rates of UVB-absorbing sunscreens in 80% methanol on irradiation with 〉290 nm light decreased in the order 2-ethylhexyl 4-dimethylaminobenzoate (DMABA-2EH) ≫ 2-ethylhexyl 4-methoxycinnamate (MCA-2EH) and the experimental sunscreens, 1-(1,1-dimethylethyl)-3-octanoyl-4,4-dimethyl- 1,4,5,6,-tetrahydropyridine (ICI-319) and 1-(2-methylpropyl)-3-propionyl-4,4-dimethyl-1,4,5,6-tetrahydropyridine (ICI-855). The relative photodynamic oxidation rates of UVA-absorbing sunscreens decreased in the order 4-tert-butyl-4'-methoxydibenzoylmethane (BMDBM) and 4-(2-propyl)benzophenone (PB) 〉 2-hydroxy-4'-methoxy-benzophenone (HMB) and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB). We have confirmed the photodynamic activity of DMABA-2EH for the production of singlet oxygen (1O2) using electron paramagnetic resonance (EPR) spectroscopy and the reagent 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP). We failed to detect the photodynamic production of the oxyradicals, superoxide (O2.-) and hydroxyl radical (HO.) using N-tert-butyl-a-phenylnitrone (PBN) and 5,5-dimethyl-1-pyrrolidine-1-oxide (DMPO) as a result of photochemical interference caused by these spin-trapping reagents. The uric acid photo-oxidation assay was also used to compare the photodynamic reactivity of light-reflective, microfine oxides TiO2, ZnO and ZrO2 suspended in aqueous 80% methanol. All of the microfine oxides (uncoated) showed greater photodynamic reactivity in equimolar dispersion than did any of the organic UVA- and UVB-absorbing sunscreens in homogeneous solution. In this assay the photodynamic oxidation rates for the microfine oxides decreased in the order ZnO ≫ TiO2 (anatase) 〉 ZrO2 〉 TiO2 (rutile). Resume Nous presentons un nouveau procede d'evaluation de l'activite photooxydante d'agents pour ecrans solaires base sur l'oxydation photodynamique de l'acide urique. L'acide urique a ete choisi comme test a l'oxydation en raison de sa forte reactivite a l'oxygene singulet et aux radicaux oxygene, sa haute sensibilite a la detection par les techniques electrochimiques (EC), sa faible capacite d'absorption de la lumiere, sa stabilite photochimique elevee dans le domaine UVA/UVB concerne, et sa stabilite a l'autooxydation. La demonstration du procede est effectuee au travers de l'oxydation photodynamique de l'acide urique co-irradie avec du Rose du Bengale, colorant phosensibilisateur tres efficace pour generer de l'oxygene singulet (1O2). En mettant ce test en oeuvre nous avons trouve que les vitesses relatives d'oxydation photodynamique d'ecrans solaires aux UVB dans due methanol a 80%, irradies avec une lumiere 〉 290nm, diminuent dans l'ordre: 2-ethylhexyl 4-dimethylamino-benzoate (DMABA-2EH) ≫ 2-ethylhexyl 4-methoxycinnamate (MCA-2EH) et les ecrans a l'essai: la 1-(1,1-dimethylethyl)-3-octanoyl-4,4-dimethyl-1,4,5,6-tetrahydopyridine (ICI-319) et la 1-(2-methylpropyl)-3-propionyl-4,4-dimethyl-1,4,5,6-tetrahydropyridine (ICI-855). les vitesses relatives d'oxydation photodynamique d'ecrans solaires aux UVA diminuent dans l'ordre: 4-tert-butyl-4'-methoxydibenzoylmethane (BMDBM) et 4-(2-propyl) benzophenone (PB) 〉 2-hydroxy-4'-methoxybenzophenone (HMB) et 2'2'-dihydroxy-4-methoxybenzophenone (DHMB). Nous avons confirme l'activite photdynamique du DMABA-2EH pour la production d'oxygene singulet (1O2) en utilisant la spectroscopie par resonance paramagnetique electronique et le reactif 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP). Nous n'avons pas pu detecter la production photodynamique des oxyradicaux du superoxyde (O2.) et du radical hydroxyle (HO.) a l'aide de la N-ter-butyl-a- phenylnitrone (PBN) en raison d'interferences photochimiques causees par ces reactifs spin-Bloquants. Le test de photooxydation de l'acide urique a aussi ete utilise pour comparer la reactivite photodynamique d'oxydes microfins reflechisseurs de lumiere TiO2, ZnO et ZrO2 en suspension dans du methanol aqueux a 80%. Tous ces oxydes microfins (non enrobes) ont montre une meilleure reactivite photodynamique en dispersion equimolaire que ne l'a fait aucun des ecrans solaires aux UVA et UVB en solution homogene. Lors de ce test les vitesses d'oxydation photodynamique des oxydes microfins ont diminue dans l'ordre ZnO ≫ TiO2 (anatase) 〉 ZrO2 〉 TiO2 (rutile).

Notizen: A Mn–Zn ferrite with a grain size of about 2 μm has been developed for the transformer driven at around 1 MHz. The developed ferrite exhibits considerably lower core losses than a conventional Mn–Zn ferrite with a grain size of about 10 μm at a frequency of 0.5 to 2 MHz. The thin-type transformer using the developed ferrite driven at 1 MHz shows a high efficiency of more than 95% at an output power of 10 to 17 W and a much lower surface temperature rise than the transformer using the conventional ferrite. © 1998 American Institute of Physics.

Notizen: The electrical degradation of AlInAs/GaInAs high electron mobility transistor (HEMT) due to the fluorine contamination is quantitatively explained through the comprehensive annealing experiments and bias-temperature tests. The thermal degradation rate is found to be mainly determined by the following electrochemical reaction of fluorine with donor species after the quite fast diffusion of fluorine into the AlInAs layer. It is also confirmed that the thermal degradation is stringently affected by the electric field resulting in the one-sided degradation near the anode. These findings are valuable knowledges in improving the reliability of AlInAs/GaInAs HEMT under the dc accelerated life test at high temperature. © 1996 American Institute of Physics.

Notizen: We have demonstrated a technique of directly measuring the exciton binding energy and the valence band split in the quantum well through a tunneling process. We have also measured the emission efficiency of quantum well heavy-hole excitons and light-hole excitons into the normal direction. © 1997 American Institute of Physics.

Notizen: We have observed the dressed-exciton oscillating emission in the time domain and the associated spectral splitting in the frequency domain from a GaAs single quantum well microcavity over a very broad range of cavity resonant wavelengths. The spectral splitting and temporal oscillation period have been measured to be nearly constant over two orders of magnitude variation of pump intensity, which confirms the linear bosonic feature of Wannier excitons in the weak excitation regime. © 1995 American Institute of Physics.

Notizen: The origin of the thermal instability of the AlInAs/GaInAs system is identified and a novel method to recover the thermal degradation is also demonstrated. The thermal diffusion of fluorine into the Si-doped AlInAs layer is found to be the main cause of the electrical deterioration of this system. This finding has led to a method to recover the thermal degradation by purging the fluorine off using the reannealing in the ultrahigh-vacuum condition. This method is now potentially becoming a good candidate as a tip for the AlInAs/GaInAs devices fabrication including laser diode and high electron mobility transistor. © 1995 American Institute of Physics.

Notizen: By using the second harmonic generation (SHG) microscope, which we have recently developed, two-dimensional images of ferroelectric domain structure were successfully obtained by exploiting the inhomogeneous distribution of the quadratic nonlinear optical constant in specimens. 90° domain structure of BaTiO3 was observed with intensity contrast of the second harmonic wave. A periodically inverted antiparallel domain in LiTaO3 was also observed. This fact indicates that the SHG microscope provides a new method of observing antiparallel ferroelectric domain structure in a nondestructive way, which is especially important for characterizing the quasiphase matched devices for compact blue light lasers. © 1995 American Institute of Physics.

Notizen: The application of microbubbles of pressured CO2 greatly increased CO2 concentration in the solution treated. By treatment at 6 MPa, 35°C and average residence time 15 min, L. brevis was completely inactivated at the level of dissolved CO2,γ≧ 11 (γ, Kuenen's gas absorption coefficient). E. coli and S. cerevisiae required γ≧ 17, and T. versatilis required γ≧ 21 for complete inactivation. Z. rouxii could be sterilized at 20 MPa and 26. A comparison of the continuous and batch method showed that L. brevis was inactivated completely under pressured CO2 〉 0.16 g/cm3 with the continuous method and 〉0.9 g/cm3 with the batch method.

Notizen: Summary. Beta interferon therapy was given to seven chronic hepatitis C patients with haemophilia or other haemorrhagic disorders who had received clotting factor replacement therapy. Serum alanine aminotransferase (ALT) levels ranged from 82 to 275 UL-1 and hepatitis C virus (HCV)-RNA ranged from 106 to 109 copies mL-1. HCV-genotypes were I+II in one patient, II in one, II+III in four and IV in one. Patients received 6 mega units (MU) daily of natural type beta interferon by intravenous infusion for 6 weeks. In three of seven patients, the protocol was modified to intermittent administration because neutrocytopenia (under 500 × 106 L-1) developed in two patients and thrombocytopenia (under 50 × 109 L-1) was observed in one during treatment. No modification was necessary with regard to daily and total dose. All patients received administration without any haemorrhagic complications. Six of seven patients showed improvement in serum ALT levels, and one of the patients showed normalization of ALT levels for 6 months after treatment. HCV-RNA disappeared in four patients by the end of treatment, although no one remained negative 6 months after treatment. The results of our study were similar to those reported in previous papers which described the use of alpha interferon in haemophiliacs. The reason none of the patients showed sustained loss of HCV-RNA after therapy might be associated with high HCV-RNA levels, characteristics of the HCV-genotype and prolonged duration of the disease.