Reirradiation Using 198Au Grain Brachytherapy for Recurrent Oral Cancer Cases Previously Treated by Definitive Radiotherapy.

BACKGROUND/AIM: We investigated treatment outcomes and complications during reirradiation of patients with oral cancers. PATIENTS AND METHODS: Six patients who received definitive radiotherapy for oral cancer as the initial treatment and brachytherapy for recurrence were included. Local control and overall survival rates, soft tissue and mandibular complications, and tooth extraction were investigated. RESULTS: The five-year local control and overall survival rates were 83.3% and 100%, respectively. The occurrence rate of grade 2 soft tissue and mandible complications was 33.3%, and the primary sites were the buccal mucosa and the floor of mouth. The positions of the extracted tooth in the two cases were adjacent to the tumor, and one case developed grade 2 complication of the mandible. CONCLUSION: During recurrence of the buccal mucosa and the floor of mouth cancers, reirradiation should be avoided considering mandibular complications. To avoid reirradiation-related complications, tooth extraction near the radiation field should be avoided.

Synthesis and Evaluation of 198Au/PAMAM-MPEG-FA against Cancer Cells.

BACKGROUND: There is a significant dearth of clinical biochemistry researches to evaluate the facility of exploitation of folate targeted radioactive gold-labeled anti-cancer drugs against various cancer cell lines. OBJECTIVE: The aim of this paper was to develop a gold-based compound with an efficient therapeutic potential against breast cancer. To this end, the synthesis of the 198Au/PAMAM-MPEG-FA composite was considered here. METHODS: The radioactive gold (198Au) nanoparticles were encapsulated into Folic acid (FA)-targeted Polyamidoamine dendrimer (PAMAM) modified with Maleimide-Polyethylene glycol Succinimidyl Carboxymethyl ester (MPEG). After that, anticancer assessments of the prepared 198Au/PAMAM-MPEG-FA hybrid mater against breast cancer were investigated. Further studies were also devised to compare the anticancer capabilities of the 198Au/PAMAM-MPEG-FA composite with the synthesized P-MPEG, 197Au/P-MPEG, 197Au/P-MPEG-FA, 197Au/P-FA and 198Au/P-MPEG-FA conjugates. The prepared drugs were characterized by means of various analytical techniques. The radionuclidic purity of the 198Au/P-MPEG-FA solution was determined using High Purity Germanium (HPGe) spectroscopy and its stability in the presence of human serum was studied. The cell uptake and toxicity of the prepared drugs were evaluated in vitro, and some comparative studies of the toxicity of the drugs were conducted towards the MCF7 (Human breast cancer cell), 4T1 (Mice breast adenocarcinoma cell) and C2C12 (Mice muscle normal cell). RESULTS: The results showed that cell uptake of 198Au/P-MPEG-FA nanoparticles is high in the 4T1 cell line and the order of uptake is as 4T1> MCF7> C2C12. Moreover, of the tested compounds, 198Au/P-MPEG-FA had the highest toxicity towards the cancerous 4T1 and MCF7 in all concentrations after 24, 48 and 72h (P < 0.001). Furthermore, the cytotoxicity of the drugs was concentration-dependent. CONCLUSION: On the basis of the present research, 198Au/P-MPEG-FA has been proposed as a good candidate for the induction of cell death in breast cancer, although further experimental and clinical investigations are required.

Deposition and clearance of 2 micron particles in the tracheobronchial tree of normal subjects--smokers and nonsmokers.

Deposition and clearance of inhaled particles of iron oxide labeled with (198)Au were studied in 19 normal subjects (10 nonsmokers and 9 smokers). For this purpose, monodisperse aerosols of particles with a 2 mu diameter were produced in a spinning disc atomizer. Thoracic counts and images with a scintillation camera were begun immediately after inhalation of the aerosol and continued for 6 hr. In all subjects, smokers and nonsmokers, the deposition of the particles was uniform throughout both lung fields, with approximately half of the particles deposited in the ciliated airways (tracheobronchial deposition) and half in the nonciliated airways (alveolar deposition). Tracheobronchial clearance in nonsmokers occurred immediately after inhalation, first at a fast rate for particles deposited in the largest and most central airways, and then at a slower rate for particles from the smaller and more peripheral airways. Photoscintigrams showed that the particles cleared steadily with no retention in any area. The general pattern of clearance may be likened to a model of multiple conveyor belts with speed increasing from the peripheral to the central airways in such a way as to prevent "particle jams" at airway confluence points. In smokers, tracheobronchial clearance was delayed for periods of 1-4 hr after inhalation. Furthermore, in contrast with the findings in nonsmokers, significant clearance was still occurring in many of the smokers in the 5th and 6th hr after inhalation. Also, photoscintigrams showed an abnormal accumulation of particles in the large airways several hours after inhalation of the aerosol.

Chromosomal instability induced by heavy ion irradiation.

PURPOSE: To establish the dose-response relationship for the induction of chromosomal instability in GM10115 cells exposed to high-energy iron ions (1 GeV/nucleon, mean LET 146 keV/microm) and gold ions (11 GeV/nucleon, mean LET 1450 keV/microm). Past work has established that sparsely ionizing X-rays can induce a long-lived destabilization of chromosomes in a dose-dependent manner at an incidence of approximately 3% per gray. The present investigation assesses the capacity of High-Z and High-energy (HZE) particles to elicit this same endpoint. MATERIALS AND METHODS: Clonal populations derived from single progenitor cells surviving heavy-ion irradiation were analyzed cytogenetically to identify those clones showing a persistent destablization of chromosomes. RESULTS: Dose-response data, with a particular emphasis at low dose (< 1.0 Gy), indicate a frequency of approximately 4% per gray for the induction of chromosomal instability in clones derived from single progenitor cells surviving exposure to iron ions. The induction of chromosomal instability by gold ions was, however, less responsive to applied dose, as the observed incidence of this phenotype varied from 0 to 10% over 1-8 Gy. Both iron and gold ions gave dose-dependent increases in the yield of chromosomal aberrations (both chromosome- and chromatid-type) measured at the first mitosis following irradiation, as well as shoulderless survival curves having D0=0.87 and 1.1 Gy respectively. CONCLUSIONS: Based on the present dose-response data, the relative biological effectiveness of iron ions is 1.3 for the induction of chromosomal instability, and this indicates that heavy ions are only slightly more efficient than X-rays at eliciting this delayed phenotype.

Biological detection of reduction in dose at the surface of volume sources containing beta emitters.

Dosimetry theory related to volume sources containing uniformly distributed beta-emitting radionuclides predicts a rapid drop in dose at the outer surface to approximately one half of the maximum dose within the volume. The purpose of this study was to determine if this reduction in surface dose could be observed using a measurable biological endpoint. In this study rats were injected with radiocolloids of either 198Au, 113In-m or 99Tc-m, to produce liver irradiation from their decay, or their livers were treated with external X-irradiation. After irradiation, a portion of the liver was surgically removed to stimulate cell division in the liver remnant revealing radiation damage in the form of chromosomal aberrations. The percentages of dividing cells with bridges were scored in the outer edges (0.45 mm) of the tissue sections and were compared to levels obtained from the central portion of the liver lobe. No significant difference was observed with X-irradiation or from 99Tc-m irradiation. However, irradiation with 198-Au and 113In-m (which emit large numbers of energetic electrons) produced significantly fewer aberrations in the outer layer when compared to the central portion. These differences in the distribution of biological damage allowed us to detect the predicted dose reduction at the surface of volume sources containing beta emitters.

Visceral radioisotopic lymphography of the testicle.

Scintigraphic studies made in 75 patients, respectively on 130 testicles with the aid of the organ radio-isotopic lymphography enabled to determine more exactly the location and the variety of the testicular lymph centers. It should be pointed out that in 58.5% of the patients the lymph centers are situated on the left of the middle line and only in 6.1% on the right. In some cases iliac lymph nodes were demonstrable. Attempts were made to use this method in investigation of the patients with malignant tumours of the testicles.

[Bone marrow scanning (author's transl)]. / La scintigrafi midollare ossea

Personal experience of Technetium-99m-sulfur colloid in the scintiscanning of bone marrow is reported. The method offers technical advantages over other methods and superior protection, while its only limitation is that it does not permit a dynamic study of hematopoiesis. Four pathologic scans typical of four groups of diseases may be distinguished. Further, metastatic bone marrow localisations can be diagnosed much earlier and more precisely than by radiography.

Evaluation of resin composites modified with nanogold and nanosilver.

Silver and gold have been used for centuries as antimicrobial agents. The aim of the study was to investigate diametral tensile strength, microhardness, ion release and light transmission of experimental resin composites. Flowable dental composite SDR (Dentsply, United Kingdom) was modified by nanogold, nanosilver and silica addition. The metal ion release, light transmission study, microhardness, Diametral Tensile Strength were evaluated. The experimental nanosilver-containing composites released significant amounts of Al, Si, Sr and Ba ions up to 30 days, and negligible silver ion amounts. Significant Ag ion release occurred in nanosilver- and nanogoldmodified composite. Resin composites modified with nanogold and nanosilver deposited on silica carrier exhibit lower light transmission and have opaque appearance. All experimental composites exhibited higher microhardness in comparison to non-modified resin composites. Diametral Tensile Strength of the experimental composites was comparable to the control group.