In vivo reactions in mice and in vitro reactions in feline cells to implantable microchip transponders with different surface materials.

Tissues of mice that had had microchip transponders with surfaces made of bioglass, bioglass with a polypropylene cap, parylene C, titanium or aluminium oxide inserted were examined histologically, and the growth of two lines of feline fibroblastoid cells around these transponders was examined in vitro. The results for bioglass and aluminium oxide were similar. In vitro, there were almost no cells around or on the transponders; in vivo, there was often granulomatous inflammation in the surrounding tissue. In the case of the bioglass, this reaction seemed to be induced by petrolatum, which was added by the manufacturer for technical reasons, rather than by the bioglass itself. In some of the mice, polypropylene caused a proliferation of granulation tissue. In vitro, the cellularity around the transponders was high, but only a moderate number of cells were found on the material. In vivo, around the parylene C transponders, there were occasionally small fragments of foreign material, surrounded by a foreign body reaction; in vitro, the results for parylene C resembled those for polypropylene. In vivo, particles of titanium were sometimes visible in the connective tissue adjacent to the titanium transponders, and sometimes accompanied by a foreign body reaction; in vitro, a confluent layer of cells developed on the transponders, with a high cellularity around them.

Fibrosarcoma tras radiodermitis crónica profesional de larga evolución / Sarcoma caused by long-time occupational cronic radiodermitis

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[Fibrosarcoma after silicone breast augmentation: is there a connection?].

We describe a 42-year-old woman in whom bilateral fibrosarcoma of the breast was diagnosed 15 years after bilateral breast augmentation with silicone implants. 3 years prior to admission the implants were replaced and 2 years prior to admission mammography showed a nodule in the left breast which biopsy showed to be fibrosarcoma. The implants were removed from both breasts and she was given chemotherapy but later that year underwent bilateral mastectomy. Despite chemotherapy, as well as adjuvant radiotherapy, the disease progressed, with involvement of the lungs and the skin of the left hemithorax. She was admitted repeatedly for severe anemia caused by bleeding from the malignant skin lesions, and died less than 2 years after diagnosis of the disease. Not all reports in the literature find a significant connection between silicone implants and subsequent development of breast cancer, but there are reports that do connect them. Breast fibrosarcoma is not significantly more frequent after silicone augmentation, but still there is controversy as to whether there is a connection between silicone implants and breast malignancy. In the patient we present, the prolonged exposure to silicone may have been a predisposing factor for the development of bilateral fibrosarcoma, since other known risk factors for breast cancer were denied.

Carcinogenicity of combined ultraviolet B radiation and psoralen plus ultraviolet A irradiation treatment of mice.

Psoralen plus ultraviolet A (PUVA) therapy and UVB phototherapy are frequently used in the treatment of psoriasis and other skin diseases. Both treatments are thought to be carcinogenic, but little is known about their interaction in the induction of skin cancer. Tumors induced in mice treated with both PUVA and UVB, either given sequentially or concurrently, seemed to be more antigenic as a group than tumors treated by PUVA alone, as determined by their lower frequency of growth when transplanted into naive mice. In this study, we treated C3H mice with a subcarcinogenic dose of UVB radiation for 4 weeks, followed by PUVA treatment for 41 weeks (sequential experiment) or with both UVB radiation (minimal carcinogenic dose) and PUVA for 41 weeks (concurrent experiment) and monitored the development of skin cancers. Although a few tumors appeared earlier in the groups treated with both UVB and PUVA in both experiments, no significant differences were observed in the rate of tumor development in mice treated with UVB and PUVA versus those treated with PUVA alone.

The effect of hyperthermia on the early- and late-appearing mouse foot reactions and on radiation carcinogenesis: Part II. Effect on radiation carcinogenesis (thermal enhancement and oxygen enhancement).

The effect of hyperthermia on radiation carcinogenesis was investigated in the C3Hf/Sed mouse foot. The foot was irradiated under hypoxic conditions, in air, or under hyperbaric oxygen conditions to evaluate the oxygen effect. Hyperthermia at 43.5 degrees C for 45 min was given by immersing the animal foot into a constant temperature water bath. A malignant tumor in the irradiated foot was first observed congruent to 250 days after irradiation. Tumors developed in the irradiated area until day 850. RCD50, or 50% radiation carcinogenesis dose was the endpoint and was calculated based on the tumor incidence 650 days after irradiation. RCD50 following radiation given alone under hypoxic conditions was 66.3 (60.0-73.2) Gy, and the oxygen enhancement ratio (hypoxic/hyperbaric oxygen) was 3.0 (2.5-3.5). Radiation carcinogenesis was enhanced by hyperthermia given with a 20 min treatment interval with no significant alteration in the oxygen effect. Thermal enhancement was greatest when hyperthermia was given 20 min prior to irradiation (2.5 [2.2-2.9] under hypoxia). No thermal enhancement was observed when two treatments were given with a treatment interval of 2 days. The median time to develop a malignant tumor decreased with increasing radiation dose. This median time was shorter following combined hyperthermia and irradiation (423 days) than following radiation alone (504 days). Histological studies revealed that more than 80% of tumors were soft tissue sarcomas, and the most common tumor was fibrosarcoma. Squamous cell carcinoma was found in 7% of all tumors.