Neighborhood frequency does affect performance in the Reicher task: encoding or decision?

Three experiments using the Reicher task show that performance on low-frequency words is disrupted if the incorrect alternative forms a higher frequency word. This neighborhood frequency effect occurs for both energy and pattern masks and for different sets of items. When the upcoming word is primed and its accessibility is enhanced, the neighborhood frequency effect is eliminated. Experiments 4a and 4b tested the neighborhood frequency effect using a same-different task and a signal-detection analysis. Neighborhood frequency affected the decision criterion but not the sensitivity of the perceptual system. Experiment 5 showed that many words with a frequency in the range from 1 to 5 per million are not recognized out of context. These results are consistent with the hypothesis that frequency effects in the Reicher task are caused by a bias in the decision system and can be simulated with the stochastic activation-verification model.

Effect of photodynamic therapy on a heterotransplanted human parotid tumor.

To evaluate the effect of photodynamic therapy on human parotid tumors we used tumor specimens obtained from parotid surgery on a consecutive group of patients. The tumors were transplanted into a subcutaneous pocket of nude mice. The original human tumors were pleomorphic adenoma (four), adenolymphoma (one), acinic cell carcinoma (one), sarcoma (one) and low-grade adenocarcinoma (one). The most aggressive growth was seen in the low-grade adenocarcinoma. We re-implanted this tumor on ten mice bilaterally, and treated the tumors with photodynamic therapy (PDT), resulting in a mean depth of tumor necrosis of 5.4 mm (1-10 mm). In three cases we found vital tumor cells in the periphery of the tumor after treatment, with several new blood vessels in the surrounding tissue, indicating a great potential for neo-angiogenesis in this tumor. In order to evaluate the possible nerve damage subsequent to the photodynamic therapy, the ischiadic nerve in 24 lower limbs of nude mice were investigated. In one case only the macroscopical and histological investigation revealed signs of nerve damage. The current study demonstrates that the nude mice implantation model is excellent to investigate growth in both malignant and benign parotid tumors, and to test new therapeutic modalities. Photodynamic therapy seems to have a possible role in the future management of the malignant lesions of the parotid gland, in cases where radical surgery for some reason is not achievable.

[Photodynamic therapy. A new method for the treatment of cancer]. / Fotodynamisk terapi. En ny metode til kraeftbehandling.

This therapy is best understood as light activated chemotherapy. The chemotherapeutic agents, so-called photosensitizers, are relatively harmless without light. The photosensitizer is given systemically and is concentrated or retained in malignant tissue, the activating light is applied locally. The therapy is approved in The United States of America, Canada, The Netherlands, France, Germany and Japan for treatment of certain malignancies. An approval is pending at The Danish National Board of Health. Photodynamic therapy is potentially curative for many superficial or luminal tumours, and can eradicate micrometastases in the tumour bed.