Superoxide dismutases enhance H2O2-induced DNA damage and alter its site specificity.

Superoxide dismutases (SODs) are involved in the protection of cells from oxygen toxicity. However, several papers have reported that the overexpression of CuZn-SOD causes oxidative damage to cells. We investigated a mechanism by which an excess of SODs accelerates oxidative stress. The presence of CuZn-SOD, Mn-SOD or Mn(II) enhanced the frequency of DNA damage induced by hydrogen peroxide (H2O2) and Cu(II), and altered the site specificity of the latter: H2O2 induced Cu(II)-dependent DNA damage with high frequency at the 5'-guanine of poly G sequences; when SODs were added, the frequency of cleavages at thymine and cytosine residues increased. SODs also enhanced the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine by H2O2 and Cu(II). We conclude that SODs may increase carcinogenic risks, e.g. of tumors in Down syndrome.

A spatial light modulator based on fused-silica plates for adaptive feedback control of intense femtosecond laser pulses.

A novel spatial light modulator (SLM) made of an array of fused-silica plates was developed for the purpose of feedback control for intense femtosecond laser pulses over a wide spectral range. Dispersion compensation for 20-fs pulses from a Ti:sapphire oscillator was successfully demonstrated using the SLM with an adaptive feedback control system. The SLM was also applied to the output pulses from a Ti:sapphire amplifier for compensation of material.

Self-compression of high-intensity femtosecond optical pulses and spatiotemporal soliton generation

Self-compression of high-intensity femtosecond pulses has been observed in a number of atomic and molecular gases and solid bulk material. The evolution of the femtosecond pulse parameters during the self-compression has been studied under a variety of experimental conditions. Generation of spatiotemporal solitons has been achieved by the combined action of self-compression and self-focusing.

Expression of vitamin D receptor in cultured human keratinocytes and fibroblasts is not altered by corticosteroids.

Topical vitamin D3 therapy is one of the mainstays of psoriasis treatment. However, the effectiveness of combination therapy with topical vitamin D3 and corticosteroids is still controversial. It has been reported that topical vitamin D3 treatment following topical corticosteroids is less effective than that without preceding corticosteroid treatment. We hypothesized that vitamin D receptor (VDR) in the skin is down-regulated by topical corticosteroids. To obtain support for this hypothesis, we determined VDR protein levels in cultured keratinocytes and fibroblasts after corticosteroid treatment. VDR levels were quantified by Western blot analysis with a Fluorolmager. Keratinocytes and fibroblasts were obtained from four psoriasis patients and four normal controls. VDR levels were altered in neither normal nor psoriatic keratinocytes by 2-day incubation with dexamethasone (1x10(-9)-1x10(-6) M) or clobetasol propionate (1x10(-9)-1x10(-6) M). Similarly, VDR levels in normal and psoriatic fibroblasts were not affected by 2-day incubation with dexamethasone (1x10(-6) M). These findings suggest that down-regulation of VDR by topical corticosteroids in keratinocytes and fibroblasts of psoriasis is unlikely.

Inhibition of nitric oxide formation and superoxide generation during reduction of LY83583 by neuronal nitric oxide synthase.

6-Anilino-5,8-quinolinedione (LY83583) has been widely used as an agent to reduce levels of nitric oxide (NO)-dependent cGMP in tissues. We report here that suppression of NO formation and production of superoxide during enzymatic reduction of LY83583 by neuronal NO synthase appeared to be potentially involved in the pharmacological action caused by LY83583. LY83583 suppressed neuronal NO synthase activity of 20,000 x g rat cerebellar supernatant preparation in a concentration-dependent manner (IC50 value = 12.9 microM). A kinetic study revealed that LY83583 is a competitive inhibitor with respect to NADPH, with a Ki value of 2.57 microM. With purified neuronal NO synthase it was found that LY83583 was a potent inhibitor of NO formation by the enzyme and served as efficient substrate for reduction with a specific activity of 173 nmol of NADPH oxidized per mg of protein per minute. The reductase activity was stimulated about 19.8-fold by addition of CaCl2/calmodulin, indicating that the presence of CaCl2/calmodulin is essential to express maximal activity of LY83583 reduction. Although LY83583 was a good substrate for both NADPH-cytochrome P450 reductase (P450 reductase) and DT-diaphorase, these flavin enzymes-catalyzed reductions of LY83583 were less than the neuronal NO synthase-mediated reduction in the presence of CaCl2/calmodulin. Enzymatic generation of superoxide during reduction of LY83583 by neuronal NO synthase, P450 reductase or DT-diaphorase was confirmed by electron spin resonance (ESR) experiments. Thus the present results indicate that a benzoquinone derivative LY83583 appears to interact with the P450 reductase domain on neuronal NO synthase, resulting in inhibition of NO formation and superoxide generation, which is involved in suppression of intracellular cGMP content.

Cytotoxic, hepatoprotective and free radical scavenging effects of propolis from Brazil, Peru, the Netherlands and China.

Propolis is a resinous hive product collected by honeybees from various plant sources. The composition of the propolis depends upon the time, vegetation and the area of collection. Thus, quality evaluation of the propolis is important, before use in food and beverages. For this propose three different biological activities were carried out, i.e. 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, cytotoxicity and hepatoprotective activity, of MeOH and water extracts of nine different propolis from Brazil, Peru, the Netherlands and China. The results showed that water extracts of six Brazilian and a Chinese propolis possessed stronger DPPH free radical scavenging activity than the corresponding MeOH extract, whereas in the case of Netherlands and Peruvian propolis MeOH extract exhibited stronger DPPH free radical scavenging activity. The MeOH extracts of all propolis possessed stronger cytotoxicity than the corresponding water extract towards murine colon 26-L5 carcinoma and human HT-1080 fibrosarcoma cells. The result of hepatoprotective activity of Brazilian propolis on D-galactosamine (D-GalN)/tumor necrosis factor-alpha (TNF-alpha)-induced cell death in primary cultured mouse hepatocytes were found in accordance with the grade set up by beekeepers in Brazil.

Arthroscopic debridement for dialysis shoulders.

PURPOSE: To arthroscopically treat "dialysis shoulder," severe shoulder pain in patients on long-term hemodialysis. This pain occurs only at rest such as during hemodialysis or while sleeping and is temporarily alleviated by assuming the sitting position or moving the shoulder joint. Limitations in range of motion and pain with overhead activity or the arm in the forward flexed position are not the patient's chief complaints. Although frozen shoulder and impingement syndrome may be observed as complications, pain at rest is the most characteristic. TYPE OF STUDY: Clinical research on arthroscopic debridement to treat dialysis shoulder. METHODS: We performed arthroscopic debridement of 36 dialysis shoulders in 29 patients. Only complete debridement in the glenohumeral joint and subacromial bursa was performed, without invasion to the bone and ligaments. RESULTS: The pain improved in 34 shoulders in 27 patients (94%) a mean of 29.8 months after surgery, showing satisfactory results. In this group, the mean Japan Orthopaedic Surgery Association shoulder score (maximum 100 points) was 66.4 points before surgery but increased to 86.6 points postoperatively, statistically significant by 2-group t test. CONCLUSIONS: We decided before beginning the study that no postoperative rehabilitation would be necessary. There were no complications and no need for further surgery, with all but 2 of the patients being satisfied with their postoperative condition.

[Concentration of isepamicin sulfate in bone marrow blood].

Fifteen patients who were performed a rotator cuff repair were subjected for the determination of a concentration of isepamicin sulfate (ISP), which was infused intravenously, in venous blood and bone marrow blood. The concentrations were measured at 0, 30, 60 minutes after the injection. There was no statistically significance between ISP concentrations in venous and bone marrow blood. This study revealed that the transference of ISP to the bone marrow was excellent.

[The arthroscopic surgery of the shoulder. A topological and clinical study].

A topological study was made of the structure about the acromion using cadavers. Clinical application of arthroscopic surgery: A total of 110 patients underwent operation by my newly devised arthroscopic procedure. Through anatomical studies and the development and clinical trials of auxiliary devices (Step Cannulation System and Acromion Gauge) a safer and more reliable procedure of arthroscopic surgery for impingement syndrome was esablished. A therapeutic plan, involving arthroscopic surgery, for sports-related labral injury was established. Labral injuries were classified into 3 types. procedures of arthroscopic surgery suited for individual types were developed and aftertherapy was carried out on my own program, and all patients returned to sporting activities. Arthroscopic surgery for rotator cuff tear and rheumatoid disease of shoulder was established.

Direct fabrication of microgratings in fused quartz by laser-induced plasma-assisted ablation with a KrF excimer laser.

We report precision microfabrication of fused quartz by laser ablation with a conventional UV laser for what is believed to be the first time. A high-quality micrograting structure is fabricated in fused quartz by a novel technique of laser-induced plasma-assisted ablation with a single KrF excimer laser (248 nm). The plasma generated from a metal target by laser irradiation effectively assists in ablation of the fused-quartz substrate by the same laser beam, although the laser beam is transparent to the substrate. A grating with a period of 1.06 mum is achieved by use of a phase mask. We can control the grating depth to 300 nm by changing the pulse number. This technique permits high-quality microfabrication of electronic and optoelectronic devices based on fused quartz and related silicate materials by use of a conventional UV laser.

Direct generation of circularly polarized pulse from a transversely excited atmospheric CO(2) laser by injection locking.

The injection technique was applied to the generation of a circularly polarized pulse, with an energy of more than 5 J, directly from a transversely excited atmospheric CO(2) laser oscillator.

Enhanced scattering of higher-order anti-Stokes waves by polarization switching.

The polarization-switching technique has been successfully applied to the enhancement of scattered anti-Stokes powers in the ultraviolet region. Anti-Stokes waves up to the fifth order were observed in stimulated rotational scattering of hydrogen, and their pulse widths were approximately 300 psec (FWHM), which is shorter than the dephasing time of the medium and the switching time.

High-energy conversion efficiency of transient stimulated Raman scattering in methane pumped by the fundamental of a femtosecond Ti:sapphire laser.

We studied stimulated Raman scattering in pressurized methane in the highly transient regime pumped by 140-fs 0.7-mJ pulses from a Ti:sapphire (Ti:S) laser tuned at 750 nm. Energy-conversion efficiency of the first Stokes of more than 15% was achieved, with no strong sign of saturation with as much as 40 atm (1atm=760Torr) of Raman gas pressure. To our knowledge, this is the highest conversion efficiency of transient stimulated Raman scattering generated directly from the fundamental of a Ti:S laser.

High-order harmonic generation by subpicosecond KrF excimer laser pulses.

We investigated the generation of high-order harmonics of a KrF excimer laser (80 mJ, 0.5 ps) in rare gases (He, Ne) and molecular gases (N(2), O(2)). The highest-order harmonic, 7.1 nm, the 35th, was observed in He and Ne, and 8.6 nm, the 29th, in N(2) and O(2). Our experimental results suggest that the high-order harmonics are emitted from ionized atoms. The maximum photon energy of the high-order harmonics may be restricted by phase mismatching caused by free electrons.