No abstract

This study was conducted to address the question of how cancers of different histologies of the head and neck region responded to photodynamic therapy (PDT). Five human cancer cell lines were investigated: two squamous cell carcinoma lines (pharynx and tongue), mucoepidermoid carcinoma (submaxillary gland), rhabdomyosarcoma (embryonic) and adenocarcinoma (colon). The cell lines were treated with haematoporphyrin derivative (HpD) at doses of 0.78-25Mug ml(-1), with excitation of the absorbed drug by a 'black light' source (340-380 nm). An MTT assay demonstrated different PDT responses among the various cell types. On the basis of LD(50), the sensitivity of the different cell lines was ranked as follows: adenocarcinoma> squamous cell carcinoma> rhabdomyosarcoma> mucoepidermoid carcinoma. The magnitude of the LD(50) was suggested by a drug uptake study to be governed in part by cellular levels of sensitizer and in part by intrinsic cell sensitivity. This study provided information that may help to identify the histological types of head and neck cancers that would respond favourably to PDT.

No abstract

A simple high-temperature furnace with two independent heating zones was developed based on the moving-temperature-gradient concept with an operating range of 400 to 1,200 C. Programmable temperature reduction rates of the two heating zones are independently controlled in a closed chamber for better thermal stability throughout the growth zone. In order to eliminate the driving mechanism and reduce subtle vibration, which could adversely affect crystal quality, the charge crucible and furnace are made stationary during the growth process. Measurement results of temperature distributions of gradient drifting rates at various positions along the growth zone are presented. The growth of CsI(Tl) scintillation crystals prepared from a mixture of 99.9% pure CsI powder and Tl powder, using the growth rate of 1 mm/h, temperature gradient of 25.5 C/cm, and temperature gradient drift rate of 2.5 C/h, was achieved with crystal sizes of 10 and 22 mm diameter, both 70 mm in length. Test results of gamma energy resolution at 662 keV of Cs-137 spectrum measurement revealed a resolution of 7-9%.

A simple high-temperature furnace with two independent heating zones was developed based on the moving-temperature-gradient concept with an operating range of 400 to 1,200 C. Programmable temperature reduction rates of the two heating zones are independently controlled in a closed chamber for better thermal stability throughout the growth zone. In order to eliminate the driving mechanism and reduce subtle vibration, which could adversely affect crystal quality, the charge crucible and furnace are made stationary during the growth process. Measurement results of temperature distributions of gradient drifting rates at various positions along the growth zone are presented. The growth of CsI(Tl) scintillation crystals prepared from a mixture of 99.9% pure CsI powder and Tl powder, using the growth rate of 1 mm/h, temperature gradient of 25.5 C/cm, and temperature gradient drift rate of 2.5 C/h, was achieved with crystal sizes of 10 and 22 mm diameter, both 70 mm in length. Test results of gamma energy resolution at 662 keV of Cs-137 spectrum measurement revealed a resolution of 7-9%.