Search for clastogenic factors in the plasma of locally irradiated individuals.

In studies reported in the 1960s and in several investigations since, plasma from irradiated individuals was shown to induce chromosomal aberrations when transferred into normal blood cultures. In the present study, the aim was to investigate the occurrence of these clastogenic factors (CF) using markers representing DNA damage produced in reporter lymphocytes that are treated with plasma from locally exposed individuals. Blood plasma was obtained from clinical patients with benign conditions before and after they had received radiation to small treatment volumes. Three patient groups were studied: (I) marginal resected basal cell carcinoma, (II) painful osteoarthritis of the knee, and (III) painful tendinitis of the elbow or the heel. Patients in each treatment group obtained the same fractionated treatment regimen, ranging from a total dose of 40 Gy (8 × 5 Gy, 2 factions/week) to a very small volume (1-3.5 cm³) in group I to a total dose of 6 Gy (6 × 1 Gy, 2 fractions/week) for groups II and III (treatment volumes 800-1150 cm³ and 80-160 cm³, respectively). The presence of CF in the plasma was investigated through cytogenetic (chromosomal aberrations, micronuclei) assays and kinetics of early DNA damage (γ-H2AX foci) in reporter cells. With the experimental settings applied, local radiation exposure had no apparent effect on the induction of CF in patient plasma; no deviations in chromosomal aberrations or micronucleus or focus induction were observed in reporter cells treated with postexposure plasma with respect to pre-exposure samples when the mean values of the groups were compared. However, there was a large interindividual variation in the plasma-induced DNA-damaging effects. Steroid treatment of patients was demonstrated to be the most influential factor affecting the occurrence of plasma factors; plasma from patients treated with steroids led to significant reductions of γ-H2AX foci and reduced numbers of chromatid aberrations in reporter cells. In addition to the locally exposed patients, newly obtained plasma samples from three radiological accident victims exposed in 1994 were examined. In contrast to the patient data, a significant increase in chromosomal aberrations was induced with plasma from two accident victims.

Low-dose radiotherapy (LD-RT) and the modulation of iNOS expression in adjuvant-induced arthritis in rats.

PURPOSE: Low-dose radiotherapy (LD-RT) of arthritic joints applied during the peak of the acute inflammatory response improves the clinical and histomorphological development of adjuvant arthritis. The study was undertaken to investigate the cellular composition of the inflammatory infiltrate and the expression of the pro-inflammatory and anti-inflammatory enzymes, inducible nitric oxide synthase (iNOS), cyclo-oxygenase 2 (COX-2) and haem-oxygenase 1 (HO-1), in response to LD-RT. MATERIALS AND METHODS: Adjuvant arthritis in female Lewis rats was induced by intradermal injection of heat-inactivated mycobacterium tuberculosis on day 0. Both arthritic hind paws were sham irradiated (group 1) or X-irradiated with either 5 x 1.0 Gy (group 2) or 5 x 0.5 Gy (group 3) from days 15 to 19 after induction (15 animals/group). On days 21 (n=12 joints/group) and 30 (n=18 joints/group), cryostat sections were analysed histologically and immunohistologically after specific staining for macrophages, iNOS, COX-2 and HO-1. RESULTS: A total of 5 x 1.0 Gy or 5 x 0.5 Gy led to a significant reduction of clinical symptoms from days 21 to 29, and a highly significant reduction of cartilage and bone destruction on day 30. Macrophage-positive areas could be detected continuously throughout the periarticular infiltrate, and were slightly reduced after LD-RT on days 21 and 30. This reduction was more pronounced after 5 x 1.0 Gy. Following LD-RT, the iNOS score was reduced by about 45-50% on days 21 (p<0.05) and 30 (p<0.001). In contrast, the HO-1 score was increased by about 50% on days 21 (p=0.08) and 30 (p=0.03). CONCLUSIONS: The clinically and histologically observed prevention of the progression of adjuvant arthritis after LD-RT given during the peak of the acute inflammatory response and the reduction of cartilage and bone destruction in the chronic phase appears to be related to the modulation of iNOS activity by low X-ray doses.

Practical realization of massively parallel fiber-free-space optical interconnects.

We propose a novel approach to realizing massively parallel optical interconnects based on commercially available multifiber ribbons with MT-type connectors and custom-designed planar-integrated free-space components. It combines the advantages of fiber optics, that is, a long range and convenient and flexible installation, with those of (planar-integrated) free-space optics, that is, a wide range of implementable functions and a high potential for integration and parallelization. For the interface between fibers and free-space optical systems a low-cost practical solution is presented. It consists of using a metal connector plate that was manufactured on a computer-controlled milling machine. Channel densities are of the order of 100/mm(2) between optoelectronic VLSI chips and the free-space optical systems and 1/mm(2) between the free-space optical systems and MT-type fiber connectors. Experiments in combination with specially designed planar-integrated test systems prove that multiple one-to-one and one-to-many interconnects can be established with not more than 10% uniformity error.

Effects of low dose radiation therapy on adjuvant induced arthritis in rats.

PURPOSE: Substantial clinical evidence shows the efficacy of low dose radiotherapy (RT) in the treatment of painful osteoarthritis. Experimental investigations into these empirically clinical observations remain scarce. This study investigated in vivo the effects of daily 5 x 1.0 Gy versus 5 x 0.5 Gy on adjuvant induced arthritis in rats in order to explore whether there is a dose dependence of anti-inflammatory efficacy. MATERIALS AND METHODS: Adjuvant arthritis in female Lewis rats was induced by intradermal injection of heat inactivated Mycobacterium tuberculosis on day 0. Both hind paws were X-irradiated daily from days 15 to 19 after induction according to four protocols (15 animals/group): group 1, 5 x 1.0 Gy (non-arthritic animals); group 2, sham-irradiated control; group 3, 5 x 1.0 Gy; group 4, 5 x 0.5 Gy. The clinical parameters arthritis score (AS), hind paw volume (HPV), body weight, and erythrocyte sedimentation rate (ESR) were determined. On days 21 and 30 histological sections of at least 12 ankle joints per group were analysed semi-quantitatively. RESULTS: Local irradiation of non-arthritic rats (group 1) with 5 x 1 Gy did not induce any arthritic signs. Sham-irradiated arthritic rats (group 2) showed a full-blown arthritic syndrome. Treatment of arthritic rats with 5 x 1 Gy (group 3) or 5 x 0.5 Gy (group 4) led to a reduction of mean AS from day 21 to 29 compared with group 2 (days 27-29--group 3: p=0.037; group 4: p=0.034), with no differences in efficacy between groups 3 and 4. Concurrently, following radiation treatment there was no further increase in HPV. At the end of the observation period, this effect demonstrated a dose-dependent level of significance (days 27-29--group 3: p=0.0036; group 4: p=0.039). A significant decrease in the ESR was noted in both irradiated arthritic groups on day 21 (group 3: p=0.015; group 4: p=0.006). The histopathological analysis revealed a highly significant reduction of cartilage and bone destruction on day 30 in both irradiated groups. CONCLUSIONS: This study confirms by objective criteria the anti-inflammatory efficacy of low dose RT and gives some indication for a dose dependence of its efficacy.

Compact planar-integrated optical correlator for spatially incoherent signals.

A new, to our knowledge, approach for the planar integration of optical correlators is demonstrated. A VanderLugt-type architecture was used to allow the processing of the spatially incoherent signals of active optoelectronic smart-pixel-device arrays. In a folded optical system all passive components were implemented as a single multiple-phase-level element. The relations among the spatial resolution, the light efficiency, and the system design parameters are derived. High signal quality and low noise levels were achieved experimentally.

Planar-integrated optical vector-matrix multiplier.

We present the design of a planar-integrated optoelectronic vector-matrix multiplier. The inherent parallel-processing potential is fully exploited by optical implementation of multiplications and summations. Planar integration makes the free-space optical system compatible with electronic VLSI technologies. It is composed of phase-only diffractive optical elements, which implement lens and multiple-beam-splitter functions. A demonstrator version of the optical system for a matrix of size 10 x 10 was fabricated on quartz glass by means of multimask lithography and reactive ion etching. It shows low cross talk and good uniformity of the signals.

Iterative optimization of phase-only diffractive optical elements based on a lenslet array.

We describe the design of Fourier-type phase-only array generators. The numerical optimization employs the Fienup algorithm, where the parageometric design of the phase retardation profile, with the form of a lenslet array, is used as the initial guess of the optimization process. This approach provides designs with high performance that can be obtained with comparatively low computing effort. This is particularly true for elements generating large spot arrays. For symmetric reconstruction fields, the optimized phase profile typically has the same symmetry as that for the reconstruction field and can be easily unwrapped.

Fabrication of microprisms for planar optical interconnections by use of analog gray-scale lithography with high-energy-beam-sensitive glass.

For an integrated free-space optical interconnection system we suggest the use of microprisms to achieve large coupling angles at low loss. Prisms were fabricated in photoresist and quartz glass by analog lithography. High-energy-beam-sensitive glass was used as the gray-tone mask. Optical testing of the prisms shows acceptable surface quality and high efficiency (95%).

Planar-integrated talbot array illuminators.

We demonstrate the planar integration of Talbot array illuminators designed to generate one-dimensional spot arrays. The array illuminator basically consists of a phase grating and a cylindrical diffractive lens integrated as a single diffractive optical element onto a transparent glass substrate. We discuss various design aspects, and we focus on problems typical for planar-integrated free-space optics like the tilted optical axis of the system. Experimental results and measurements, which were obtained from planar-integrated setups fabricated as surface-relief structures on a transparent glass substrate by use of standard photolithography, are included.

Diffractive optics and micro-optics: introduction to the feature issue.

This issue of Applied Optics features 19 articles related to the fabrication and the design of diffractive and micro-optics as well as their applications. A companion feature in the Journal of the Optical Society of America A includes papers on the modeling of diffractive elements.