Study of the effects of exposure to ionizing irradiation on the materials used for dental restoration

A quantitative study was made about the effects caused by ionizing irradiation on materials used for dental restoration (amalgams, compound resins and compomere), aiming to alleviate in bearers of head and neck cancer, the possible harmful effects of radiotherapy perceived when the repaired teething is within the radiation field. Research also encourages further studies for new alternative materials to be used in dental repair of patients submitted to radiotherapy for head and neck cancer. Test samples were submitted to a gamma radiation beam coming from a cobalt-therapy source and analyzed according to the X-ray fluorescence technique, comparing the chemical composition of the samples before and after irradiation. Radiation detectors such as an ionization chamber and a Geiger-Muller were used to measure the rate of residual dose. Gamma spectrometry with Nal detectors was also performed on the same samples. Results showed that there was no significant change in the chemical composition and that at post-irradiation, samples did not exhibit radiation emission, that is to say they had not become radioactive.

Cytostatic in vitro Effects of DTCM-Glutarimide on Bladder Carcinoma Cells

Bladder cancer is a common malignancy worldwide. Despite the increased use of cisplatin-based combination therapy, the outcomes for patients with advanced disease remain poor. Recently, altered activation of the PI3K/Akt/mTOR pathway has been associated with reduced patient survival and advanced stage of bladder cancer, making its upstream or downstream components attractive targets for therapeutic intervention. In the present study, we showed that treatment with DTCM-glutaramide, a piperidine that targets PDK1, results in reduced proliferation, diminished cell migration and G1 arrest in 5637 and T24 bladder carcinoma cells. Conversely, no apoptosis, necrosis or autophagy were detected after treatment, suggesting that reduced cell numbers in vitro are a result of diminished proliferation rather than cell death. Furthermore previous exposure to 10 mu g/ml DTCM-glutarimide sensitized both cell lines to ionizing radiation. Although more studies are needed to corroborate our findings, our results indicate that PDK1 may be useful as a therapeutic target to prevent progression and abnormal tissue dissemination of urothelial carcinomas.

Effects of broiler breeder genetic, diet type, and feeding program on maternal antibody transfer and development of lymphoid tissues in chicken progeny

Maternal antibody (MatAb) transfer is important for early chicken survivability. Diet composition and the amount of feed given to breeder pullets during rearing may affect the development of immunity and the transfer of MatAb to progeny, and could affect progeny performance and resistance to disease. The effects of broiler breeder nutrition and feeding management practices were evaluated for the transfer of MatAb to progeny and for spleen and bursa development at hatching in 2 genetic strains (A and B). In this experiment, the levels of MatAb against Newcastle disease virus were assessed by enzyme-linked immunosorbent assays in serum samples taken of pedigreed chicken progeny from hatching to 13 d of age. Chickens were fed corn-and wheat-based diets, as were their parents. The breeder feeding program and diet type altered the Newcastle disease virus MatAb found in progeny at hatching and affected how long these antibodies were maintained in circulation. Bursal follicle size at hatching was influenced by an interaction among all factors evaluated. Percentage of white pulp in the spleen was affected mainly by genetic strain and diet type, but responses varied according to the breeder feeding program. It was concluded that breeder feeding programs influence MatAb transfer and half-life, and may also affect the early development of lymphoid tissues.

Evaluation by Free Vibration Method of Moisture Absorption Effects in Polyamide/Carbon Fiber Laminates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Some effects of gamma-irradiated autologous sera on their donors

The present paper is a further step to elucidate the effect of γ-irradiated molecules and their action as immunogens. Rabbits were bled, the total serum was γ-irradiated and reinjected to the autologous donor. Bleeding and reinjection of non-irradiated serum do not produce any alteration hence the animal is able to recognize the autologous unmodified serum proteins as 'self'. Electrophoretic results demonstrate that as an effect of γ-irradiation, alteration of the normal migration properties are occurring. The obtained data are suggesting that due to the possible alteration of the molecular structure, resulting as the effect of γ-rays, the antibody forming system of the animal injected with irradiated autologous serum might recognize the substances as 'not self' what may be the possible reason of antibody formation. The presence of antibodies and probably their complexes with antigens are demonstrated by cutaneous sensibilization technics. The low level of the complement starting from the 7-9 days, the histological alteration of the kidney and the cardiac lesions are tempting to try an interpretation comparing these symptoms to those observed in serum sickness.

Niobium filtration of conventional and high-frequency x-ray generator beams for intraoral radiography. Effects on absorbed doses, image density and contrast, and photon spectra

We have studied the effects of niobium beam filtration on absorbed doses, on image density and contrast, and on photon spectra with conventional and high-frequency dental x-ray generators. Added niobium reduced entry and superficial absorbed doses in periapical radiography by 9% to 40% with film and digital image receptors, decreased the radiation necessary to produce a given image density on E-speed film and reduced image contrast on D- and E-speed films. As shown by increased half-value layers for aluminum, titanium, and copper and by pulse-height analyses of beam spectra, niobium increased average beam energy by 6% to 19%. Despite the benefits of adding niobium on patient dose reduction and on narrowing the beams' energy spectra, the beam can be overhardened. Adding niobium, therefore, strikes the best balance between radiation dose reduction and beam attenuation, with its risks of increased exposure times, motion blur, and diminished image contrast, when it is used at modest thicknesses (30 μm) and at lower kVp (70) settings. © 1995 Mosby-Year Book, Inc.

Cara inchada and cellular immunity in cattle

Attempts were made to study possible effects of the periodontal disease cara inchada (CI) on the cellular immunity of cattle, using adherence-, chemotaxis- and ph-agocytosis-determinations. Adherence of Bacteroides melaninogenicus to bovine granulocytes was significantly decreased in animals with CI. Phagacytosis of B. melaninogenicus by polymorphonuclear granulocytes (PMN) was also decreased in CI-diseased animals. Chemotaxis of the granulocytes appeared to be slightly increased in animals with CI and animals without CI coming from CI-affected herds.

Effects of Chronic Physical Activity and of Ultrasound Treatment on Bone Consolidation

The objective of this study was to investigate the effects of ultrasound treatment and physical exercise on the velocity of bone consolidation and resistance to deformation. We performed osteotomy in the upper third of the right tibia of rats. Physical training consisted of swimming 1 h per day with a load of 5% b.w. for 30 days. Therapy with medium-intensity ultrasound was applied daily on the damaged area. Wistar rats were divided into the following groups: osteotomized sedentary animals with no ultrasound treatment (1.OSnUS), osteotomized trained animals with no ultrasound treatment (2.OTnUS), osteotomized sedentary animals with ultrasound treatment (3.OSwUS). and osteotomized trained animals with ultrasound treatment (4.OTwUS). The animals were sacrificed for the following analyses: muscle glycogen, serum alkaline phosphatase at the 5th, 10th, 20th, and 30th days, test of maximum resistance to flexion, rupture flexion and mean tibial rigidity at the 30th day. Muscle glycogen was increased at the 20th day: alkaline phosphatase was elevated at the 5th and 20th days in groups 3.OSwUS and 4.OTwUS. and decreased at the 10th day. Groups1.OSnUS and 2.OTnUS did not show significant variations. In the mechanical resistance tests, we noted that ultrasound therapy and the association of physical activity used in the present study showed significant differences in bone resistance and bone rigidity after 30 days of treatment. These facts suggest that ultrasound or physical activity, or their combination may accelerate the process of bone tissue repair.

Strong interaction effects in scalar top production

We discuss effects of fragmentation and hard gluon radiation on the signal for the pair production of the lighter scalar top eigenstate t̃1 at e+e- colliders. The main emphasis is on scenarios with small stop-LSP mass splitting, where strong interaction effects can considerably modify kinematical properties of the final state.

The effects of low laser irradiation on angiogenesis in injured rat tibiae

The influence of He-Ne laser radiation on the formation of new blood vessels in the bone marrow compartment of a regenerating area of the mid-cortical diaphysis of the tibiae of young adult rats was studied. A small hole was surgically made with a dentistry burr in the tibia and the injured area received a daily laser therapy over 7 or 14 days transcutaneously starting 24 h from surgery. Incident energy density dosages of 31.5 and 94.5 Jcm-2 were applied during the period of the tibia wound healing investigated. Light microscopic examination of histological sections of the injured area and quantification of the newly-formed blood vessels were undertaken. Low-level energy treatment accelerated the deposition of bone matrix and histological characteristics compatible with an active recovery of the injured tissue. He-Ne laser therapy significantly increased the number of blood vessels after 7 days irradiation at an energy density of 94.5 Jcm-2, but significantly decreased the number of vessels in the 14-day irradiated tibiae, independent of the dosage. These effects were attributed to laser treatment, since no significant increase in blood vessel number was detected between 8 and 15 non-irradiated control tibiae. Molecular mechanisms involved in low-level laser therapy of angiogenesis in post-traumatic bone regeneration needs further investigation.

The use of planarians as in vivo animal model to study laser biomodulation effects

A variety of effects is attributed to the photo stimulation of tissues, such as improved healing of ulcers, analgesic and anti-inflammatory effects, stimulation of the proliferation of cells of different origins and stimulation of bone repair. Some investigations that make qualitative evaluations, like wound healing and evaluation of pain and edema, can be conducted in human subjects. However, deeper investigations on the mechanisms of action of the light stimulus and other quantitative works that requires biopsies or destructive analysis has to be carried out in animal models or in cell cultures. In this work, we propose the use of planarians as a model to study laser-tissue interaction. Contrasting with cell cultures and unicellular organisms, planarians are among the simplest organism having tissue layers, central nerve system, digestive and excretory system that might have been platforms for the evolution of the complex and highly organized tissues and organs found in higher organisms. For the present study, 685 nm laser radiation was employed. Planarians were cut transversally, in a plane posterior to the auricles. The body fragments were left to regenerate and the proliferation dynamics of stem cells was studied by using histological analysis. Maximum cell count was obtained for the laser treated group at the 4th experimental day. At that experimental time, we also had the largest difference between the irradiated and the non-irradiated control group. We concluded that the studied flatworm could be an interesting animal model for in vivo studies of laser-tissue interactions.

Developing new radiotherapy techniques using linac based gamma radiation sources

A major challenge in cancer radiotherapy is to deliver a lethal dose of radiation to the target volume while minimizing damage to the surrounding normal tissue. We have proposed a model on how treatment efficacy might be improved by interfering with biological responses to DNA damage using exogenous electric fields as a strategy to drastically reduce radiation doses in cancer therapy. This approach is demonstrated at this Laboratory through case studies with prokaryotes (bacteria) and eukaryotes (yeast) cells, in which cellkilling rates induced by both gamma radiation and exogenous electric fields were measured. It was found that when cells exposed to gamma radiation are immediately submitted to a weak electric field, cell death increases more than an order of magnitude compared to the effect of radiation alone. This finding suggests, although does not prove, that DNA damage sites are reached and recognized by means of long-range electric DNA-protein interaction, and that exogenous electric fields could destructively interfere with this process. As a consequence, DNA repair is avoided leading to massive cell death. Here we are proposing the use this new technique for the design and construction of novel radiotherapy facilities associated with linac generated gamma beams under controlled conditions of dose and beam intensity.

Efficient UV-visible upconversion luminescence and thermal effects in terbium-ytterbium codoped fluorogermanate vitroceramic

Cooperative energy-transfer upconversion luminescence in Tb 3+/Yb 3+-codoped PbGeO 3-PbF 2-CdF 2 vitroceramic and its precursor glass under resonant and off-resonance infrared excitation, is investigated. Bright UV-visible emission signals around 384, 415, 438 nm, and 473-490, 545, 587, and 623 nm, identified as due to the 5D 3( 5G 6 → 7F J(J=6,5,4) and 5D 4 → 7F J(J=6,5,4,3) transitions, respectively, were readily observed. The results indicate that cooperative energy-transfer between ytterbium and terbium ions followed by excited-state absorption are the dominant upconversion excitation mechanisms herein involved. The comparison of the upconversion process in a vitroceramic sample and its glassy precursor revealed that the former present much higher upconversion efficiency. The dependence of the upconversion emission upon pump power, temperature, and doping content is also examined.

γ-Radiation induces apoptosis via sarcoplasmatic reticulum in guinea pig ileum smooth muscle cells

We investigated the effects of γ-radiation on cells isolated from the longitudinal smooth muscle layer of the guinea pig ileum, a relatively radioresistant tissue. Single doses (up to 50 Gy) reduced the amount of sarcoplasmatic reticulum and condensed the myofibrils, as shown by electron microscopy 3 days post-irradiation. After that, contractility of smooth muscle strips was reduced. Ca2+ handling was altered after irradiation, as shown in fura-2 loaded cells, with elevated basal intracellular Ca2+, reduced amount of intrareticular Ca2+, and reduced capacitive Ca2+ entry. Radiation also induced apoptosis, judged from flow cytometry of cells loaded with proprium iodide. Electron microscopy showed that radiation caused condensation of chromatin in dense masses around the nuclear envelope, the presence of apoptotic bodies, fragmentation of the nucleus, detachment of cells from their neighbors, and reductions in cell volume. Radiation also caused activation of caspase 12. Apoptosis was reduced by the administration of the caspase inhibitor Z-Val-Ala-Asp-fluoromethyl-ketone methyl ester (Z-VAD-FMK) during the 3 day period after irradiation, and by the chelator of intracellular Ca2+, 1,2-bis(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid (BAPTA), from 1 h before until 2 h after irradiation. BAPTA also reduced the effects of radiation on contractility, basal intracellular Ca2+, amount of intrareticular Ca2+, capacitative Ca2+ entry, and apoptosis. In conclusion, the effects of gamma radiation on contractility, Ca2+ handling, and apoptosis appear due to a toxic action of intracellular Ca2+. Ca2+-induced damage to the sarcoplasmatic reticulum seems a key event in impaired Ca2+ handling and apoptosis induced by γ-radiation. © 2008 Elsevier B.V. All rights reserved.

Anticlastogenic effect of β-glucan, extracted from Saccharomyces cerevisiae, on cultured cells exposed to ultraviolet radiation

β-glucan is an important polysaccharide due to its medicinal properties of stimulating the immune system and preventing chronic diseases such as cancer. The aim of the present study was to determine the anticlastogenic effect of β-glucan in cells exposed to ultraviolet radiation (UV). Chromosome aberration assay was performed in drug-metabolizing cells (HTC) and non drug-metabolizing cells (CHO-K1 and repair-deficient CHO-xrs5), using different treatment protocols. Continuous treatment (UV + β-glucan) was not effective in reducing the DNA damage only in CHO-xrs5 cells. However, the pre-treatment protocol (β-glucan before UV exposition) was effective in reducing DNA damage only in CHO-K1 cells. In post-treatment (β-glucan after UV exposition) did not show significative anticlastogenic effects, although there was a tendency toward prevention. The data suggest that β-glucan has more than one action mechanism, being capable of exerting desmutagenic as well as bio-antimutagenic action. The findings also suggest that the presence of the xenobiotic metabolizing system can reduce the chemopreventive capacity of β-glucan. Therefore, these results indicate that β-glucan from Saccharomyces cerevisiae can be used in the prevention and/or reduction of DNA damage. © 2012 Springer Science+Business Media B.V.