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.

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.

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). .

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.

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.

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.

Contact urticaria with anaphylactic reactions caused by occupational exposure to iridium salt.

This paper presents the case of a non-smoking and non-atopic male, exposed to iridium chloride at work, who developed respiratory tract symptoms and contact urticaria. Application of iridium salt to normal skin caused contact urticaria. An iridium chloride prick test showed a positive reaction and a scratch test produced anaphylactoid reactions. Platinum salt allergy was excluded through prick testing with hexachloroplatinate solution. There is no previous report describing a case where an individual has a positive prick test reaction to iridium salts and simultaneously a negative one to platinum salts. The results are interpreted as immediate-type hypersensitivity (Type I allergy?) to iridium salt. The route of sensitization was probably through the airways. Further testing showed that iridium salt allergy could persist for at least 18 months after exposure ceases. 14 employees at the same factory were prick tested with iridium and platinum salts with negative results. Prick testing is recommended as a method of first choice when investigating a person with suspected iridium salt allergy.

Occupational radiodermatitis from Ir192 exposure.

3 cases of occupational radiodermatitis from Ir192 exposure in personnel handling a gamma ray projector in industrial radiography are presented. The diagnosis was confirmed histologically. The nature and use of the industrial machines are described.

[Side effects of postoperative irradiation of uterine cancer with high dose rate iridium and low dose rate radium]. / Nebenwirkungen der postoperativen High-dose-rate-Iridium- und Low-dose-rate-Radium-Bestrahlung beim Korpuskarzinom.

A report is given about reversible and irreversible complications following postoperative irradiation in cases of endometrial carcinoma. Intravaginal brachytherapy was performed. In advanced cases or in cases with poor prognosis (tumor grading) percutaneous irradiation was added (Co60). In 156 cases low-dose-rate irradiation (Ra226) and in 143 cases high-dose-rate irradiation (Ir192) was applied intravaginally. Reversible complications (cystitis, proctitis) could be observed following Radium in 7%, following Iridium in 14%. Irreversible complications (fistulas, stenoses): 1.9% following Radium and 3.5% following Iridium. When high-dose-rate irradiation was combined with percutaneous Co60 therapy, reversible complications occurred in 22.8%. After changing the Iridium-therapy scheme (reduction of dose from 10 to 7 Gy and irradiation only of the upper two thirds of the vagina) complications only could be observed in the same level as in Radium-therapy. High-dose-rate irradiation does not need hospitalization of the patients.

Early and late effects on the normal dog brain of permanent interstitial iridium-192 irradiation.

To investigate the effects of a permanent interstitial source of gamma-irradiation on normal brain tissue, single iridium-192 (Ir-192) wires (1.05 mCi) were stereotactically implanted into the left centrum semiovale of adult dogs (survival times, 25, 46, 74, 230 and 362 days). Within 25 days, a coagulation necrosis developed in the immediate vicinity of the radioactive source. In later stages, the necrosis increased in size and became progressively mineralized. Staining for extravascular immunoreactive serum proteins revealed the presence of a chronic perifocal vasogenic edema, which extended into the white matter of the entire ipsilateral hemisphere. This edema persisted through all stages and showed a significant decrease only in the animal with a 1-year survival. A reactive gliosis with formation of a dense network of glial fibrillary acidic protein-positive astrocytes developed around the central necrosis in the adjacent white matter and, at later stages, in the contralateral hemisphere. Demyelination was restricted to the ipsilateral centrum semiovale without affecting the internal capsule or the contralateral hemisphere. It was present as early as 25 days and showed no tendency to increase at later stages. Analysis of the sequential morphological changes following Ir-192 implantation suggests that the central coagulation necrosis represents a direct radiation effect, the sharp focal delineation of which can be explained by the physical characteristics of the radiation source, i.e., rapid fall-off of the dose at short distances. Due to the continuous emission of radiation energy, there is a perifocal zone with overlapping of progressive radiation damage and tissue organization. This focus becomes the source of a chronic vasogenic edema, which in turn is most likely to be responsible for the partial demyelination of the adjacent centrum semiovale. The widespread reactive gliosis observed at all stages may also, in part, be a consequence of chronic vasogenic edema, but its distribution suggests that direct radiation effects may also be involved.

[Chronic radiation sequelae in the rat rectum following intracavitary irradiation with different doses]. / Chronische Strahlenfolgen am Enddarm der Ratte nach intrakavitärer Bestrahlung mit unterschiedlicher Dosisleistung.

The dependence of chronic radiation damage of the rectosigmoid on dose, dose rate and irradiated volume after intracavitary irradiation with an oscillating iridium source was studied in rats. The incidence of large bowel stenosis increased with increasing dose, dose rate and volume. The nominal dose leading to 50% incidence of stenosis was 27 Gy at 2 Gy/min, 32.5 Gy at 0.2 Gy/min and 51 Gy at 0.05 Gy/min.

[Complications of preoperative high-dose-rate iridium-192 irradiation in cervix uteri carcinoma]. / Komplikationen der präoperativen High-dose-rate-Iridium-192-Vorbestrahlung beim Gebärmutterhalskarzinom.

A report is given about the experience in preoperative, nonfractionated high-dose iridium-192 irradiation in cases of carcinoma of the cervix uteri. A few days prior to radical hysterectomy a dose of 20 Gy (in 2 cm distance) was applied locally by means of a loop-applicator (afterloading technique, Buchler). In cases without postoperative irradiation severe vaginal necroses, in cases with postoperative irradiation severe local and peripheral lesions were observed. In 8 of 10 cases irradiated pre- and postoperatively, another surgical intervention was necessary because of complications in the urinary or intestinal tract. This publication is presented as a warning for preoperative high-dose irradiation with 20 Gy applied locally in cases of carcinoma of the cervix uteri.

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.

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.

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.

[Tissue reaction with platinum-iridium insulated electrodes (author's transl)]. / Untersuchungen zur Gewebeverträglichkeit lackisolierter Platin-Iridium-Elektroden.

Pt-Ir-electrodes were coated with different insulations. Some of the insulations proved to be highly cytotoxic. Pt-Ir (9:1) electrodes coated with "PYRE-M.L." were easy to handle and did not show any cytotoxic effects. A change of electric impedance was found when the voltage was raised and platinum had changed the surface of the cathode.