Indium and iridium: Two rare metals with a high rate of contact sensitization.

BACKGROUND: Humans are exposed to a variety of metals on a daily basis, and nickel is the most frequent contact allergen. Little is known about the frequency of sensitization to indium and iridium. OBJECTIVES: Study the prevalence of indium and iridium sensitization and evaluate the optimal patch test conditions. METHODS: A total of 364 patients were patch tested at the allergy unit of the University Hospital of Basel. Pure metals, metal chlorides, and metal sulfates were applied in petrolatum or water in Inert Quadrate (IQ) test chambers for 2 days and read twice at day (D) 2, and between D4 and D7. RESULTS: Eleven patients reacted to indium salts (3.0%), 13 to iridium salts (3.6%), and one reacted to both salts. None of the patients reacted to pure metals. Nineteen of the 23 patients who reacted either to indium or iridium showed concomitant positive reactions to other metals, mainly nickel and palladium. CONCLUSION: This retrospective clinical study provides insight into the prevalence and test conditions of two rarely tested metal allergens in a large patient cohort. A considerable number of indium- or iridium-positive subjects had co-sensitization to other metals.

Comparative assessment of iridium oxide and platinum alloy wires using an in vitro glial scar assay.

The long-term effect of chronically implanted electrodes is the formation of a glial scar. Therefore, it is imperative to assess the biocompatibility of materials before employing them in neural electrode fabrication. Platinum alloy and iridium oxide have been identified as good candidates as neural electrode biomaterials due to their mechanical and electrical properties, however, effect of glial scar formation for these two materials is lacking. In this study, we applied a glial scarring assay to observe the cellular reactivity to platinum alloy and iridium oxide wires in order to assess the biocompatibility based on previously defined characteristics. Through real-time PCR, immunostaining and imaging techniques, we will advance the understanding of the biocompatibility of these materials. Results of this study demonstrate iridium oxide wires exhibited a more significant reactive response as compared to platinum alloy wires. Cells cultured with platinum alloy wires had less GFAP gene expression, lower average GFAP intensity, and smaller glial scar thickness. Collectively, these results indicated that platinum alloy wires were more biocompatible than the iridium oxide wires.

Ablation of a therapy-resistant posteroseptal accessory atrioventricular pathway: going for gold.

Posteroseptal accessory pathways are sometimes resistant to ablation because of the complex anatomy of this region. Ex-vivo experiments have demonstrated that gold-tip radiofrequency ablation catheters create deeper lesions than conventional platinum-iridium tip catheters. This case of a 62-year-old man with Wolf-Parkinson-White syndrome illustrates that the ability to create such lesions can be a very useful option when previous attempts with platinum-iridium tip catheters have failed.

Update of occupational lung disease.

OBJECTIVE: Occupational Lung Disease is an oldest but still a biggest problem in occupational health. METHODS: Steering Committee members of the Japan Society for Occupational Health (JSOH) Occupational Lung Disease Study Group selected and summarized current topics on occupational lung diseases based on expert opinion, as informed by governmental regulation, public health concerns, and frequently discussed in related academic conferences. RESULTS: The topics included in this review are professional education in medical screening skills, 2014 update of Helsinki Criteria, respiratory diseases found in the earthquake and tsunami affected regions, newly recognized occupational lung diseases, and potential respiratory health hazards. DISCUSSIONS: Although occupational lung diseases seem to stay as one of the major concerns in occupational health, screening tools and control measures are standardized for the better prevention of the diseases. As this health problem usually occurs in where the most actively economically developing area is, the patients tend to increase in emerging economic powers with huge population.

Treatment of penis carcinoma with interstitially administered iridium; comparison with radium therapy.

The results of treatment of 30 patients with penis carcinoma cured with radium and 18 patients treated with 192Ir were compared. In both groups of patients, core assessed at 3 years was obtained for a similar percentage of patients (89% and 83%). After treatment with 192Ir, radiation necrosis was observed in 16%, and after treatment with radium in 50% of patients. In both groups a similar high percentage of patients (88%) with organs preserved after treatment was found. In group of patients treated with 192Ir the percentage of very good functional effects (69%) was much higher in the group of patients treated with radium (28%).

Sequential morphological changes in the dog brain after interstitial iodine- 125 irradiation.

Iodine- 125 seeds (3.55 mCi) were stereotactically implanted into the subcortical white matter of the left coronal gyrus in six beagle dogs. Morphological changes were studied at intervals ranging from 25 to 368 days after implantation. In all of the animals, there was a calcifying necrosis 3 to 6 mm in diameter with an adjacent small zone of demyelination. There were no signs of delayed radiation damage outside the demyelinated perifocal zone. The central tissue necrosis was sharply delineated and did not increase in size after 70 days, i.e., an accumulated dose of 18,000 cGy. In addition, widespread vasogenic edema was present in the homolateral hemisphere. The morphological changes observed differed in many aspects from those found with other radioactive sources, such as gold-198, yttrium-90, or iridium-192. The low energy gamma radiation, the absence of beta radiation, and the half-life of 60.2 days makes iodine-125 a favorable radioactive source to produce a well-defined necrosis without delayed radiation damage in the surrounding brain.

Mathematical methods in biological dosimetry: the 1996 Iranian accident.

PURPOSE: To report 18 months of cytogenetic follow-up for an Iranian worker accidentally overexposed to 192Ir, the mathematical extrapolation and comparison with clinical data. MATERIAL AND METHODS: Unstable chromosome aberrations were measured using conventional cytogenetic tests by French and Iranian biological dosimetry laboratories on five occasions after the exposure. The decrease in dicentrics over time was analysed mathematically. In addition, Dolphin and Qdr extrapolations were applied to the data to check the exposure estimates. FISH determination of translocation yields was performed twice by the French laboratory and the results compared with the Dolphin and Qdr corrected values. RESULTS: Dose estimates based on dicentrics decreased from 3.1 +/- 0.4 Gy at 5 days after the accident to 0.8 +/- 0.2 Gy at 529 days. This could be fitted by double-exponential regression with an inflexion point between rapid and slow decrease of dicentrics after about 40 days. Dose estimates of 3.4 +/- 0.4 Gy for the Qdr model and 3.6 +/- 0.5 Gy for the Dolphin model were calculated during the post-exposure period and were remarkably stable. FISH translocation data at 26 and 61 days appeared consistent with the Dolphin and Qdr estimates. CONCLUSION: Dose correction by the Qdr and Dolphin models and translocation scoring appeared consistent with the clinical data and provided better information about the radiation injury than did crude estimates from dicentric scoring alone. Estimation by the Dolphin model of the irradiated fraction of the body seemed unreliable: it correlated better with the fraction of originally irradiated lymphocytes.

Radiation effects of iridium-192 implants in the cat brain.

The radiation effects of 192Ir permanent implants into the cat brain were studied with respect to morphological changes, blood flow, brain water and electrolytes. 192Ir wires (10 animals) and non-radioactive silver wires (5 control animals) were placed stereotactically into the left internal capsule. Activity of 192Ir was 0.31 mCi, and accumulated dose at 5 mm distance was 3060 rad after 21 days and 4680 rad after 35 days, respectively. None of the animals presented a neurological deficit, and the EEG recording was without significant changes. Histological damage which could be attributed to the radiation was not observed. Serum proteins, however, were detected immunohistochemically in reactive astrocytes (3x), in macrophages (2x) and as diffuse perivascular accumulation. Brain water in the white matter near the implantation site increased from 68.6 to 73.2%, corresponding to a volume increase of about 17%. There was no change in the grey matter or the opposite hemisphere. Cerebral blood flow decreased slightly but there was no relationship with the development of edema. The findings suggest that low dose rate topical irradiation of the brain produces primarily membrane dependent changes, resulting in local brain edema.

Oral and pharyngeal cancer: combined approach for multimodal therapy.

Five-year results in 60 oral and pharyngeal cancer patients treated with combined approach chemoradiotherapy (39 patients) and chemoradiotherapy plus lymph node surgery (21 patients) are reported. Complete remission (CR) was achieved in 16/39 (41%) patients treated with chemoradiotherapy alone, and in 16/21 (76%) patients who had chemoradiotherapy plus surgery. The number of CR was statistically (chi-square test) higher (p less than 0.025) in the second group. The 5-year actuarial survival was 39.7% in the group of patients treated with chemoradiotherapy plus surgery. After 5 years 53% of the patients who reached CR are living free of disease in the first group and 76% in the second group.

[Iridium 192 interstitial radiotherapy of carcinoma of the penis. Carcinologic results, dermatologic evaluation (about 87 cases) (author's transl)]. / La radiothérapie par iridium 192 des cancers de la verge. Résultats carcinologiques, étude dermatologique (à propos de 87 cas).

87 cases of epidermoid carcinoma of the penis treated by Ir 192 interstitial radiotherapy are studied. The 5 years survival rate, estimated on a 51 patients group, is 61 p. 100. Among these 51 patients, 12 had a local recurrence. The post-radiotherapy early reaction is estimated on a 79 patients group, with a mean duration of 3, 4 months. The early reaction is correlated to tumor size and not correlated to number of radio-active lines. The later dermatologic evolution is studied in 59 patients. In 22 cases, the scar remained supple, without any further local change. Local changes occurring in the 37 other cases are studied in their clinical aspect, signification and frequency. Of 34 patients followed longer than 40 months, 14 had local complications with 4 cases of local recurrence. The carcinologic reliability of this method is similar to that by surgery. It seems however it must be restricted to tumors limited to glans penis.

Exposure to an iridium-192 source in an industrial safety worker.

Radiation burn injuries account for 0.2% of burn injury admissions. Treatment of radiation burns remains challenging because of unpredictable inflammatory changes and soft tissue necrosis. Conventional treatment consists of multistaged surgical procedures. Here, we present a case of an Iridium-192 exposure treated nonoperatively. A 23-year-old man presented with a 7-day-old, less than 1% TBSA radiation burn to his right hand. He initially sought treatment at an outside hospital and plastic surgeon's office postinjury days 2 and 3. He later presented to our facility because of worsening pain, edema, and discoloration. He was admitted and hospitalized for 15 days. Narcotics were initiated and wound care consisted of daily antibiotic ointment and petroleum gauze dressings. We continued dexamethasone and pentoxyfilline for 1 week. He underwent nineteen 90-minute treatments of hyperbaric oxygen therapy during an 8-week period. He had complete wound healing 1 month postdischarge. This case report provides background on radiation burn injuries and applicability of nonoperative management in treating radiation burn injuries. Furthermore, it encourages the development of individualized treatment plans, consideration of the use of hyperbaric oxygen therapy, referral to a burn center, and consulting radiation experts for guidance.

Antimicrobial and cytotoxic effects of phosphoric acid solution compared to other root canal irrigants

Phosphoric acid has been suggested as an irrigant due to its effectiveness in removing the smear layer. Objectives : The purpose of this study was to compare the antimicrobial and cytotoxic effects of a 37% phosphoric acid solution to other irrigants commonly used in endodontics. Material and Methods : The substances 37% phosphoric acid, 17% EDTA, 10% citric acid, 2% chlorhexidine (solution and gel), and 5.25% NaOCl were evaluated. The antimicrobial activity was tested against Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Actinomyces meyeri, Parvimonas micra, Porphyromonas gingivalis, and Prevotella nigrescens according to the agar diffusion method. The cytotoxicity of the irrigants was determined by using the MTT assay. Results : Phosphoric acid presented higher antimicrobial activity compared to the other tested irrigants. With regard to the cell viability, this solution showed results similar to those with 5.25% NaOCl and 2% chlorhexidine (gel and solution), whereas 17% EDTA and 10% citric acid showed higher cell viability compared to other irrigants. Conclusion : Phosphoric acid demonstrated higher antimicrobial activity and cytotoxicity similar to that of 5.25% NaOCl and 2% chlorhexidine (gel and solution). .