In vivo and in vitro experiments on elimination of radioactive strontium deposited in bone 2.
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Animals↗
Biomedical subjects
H Tsuzuki
Publications and source records attributed to H Tsuzuki.
In vitro effect of hyperthermia on chemoenhancement and uptake of cisplatin in human pharyngeal carcinoma KB cells.
The purpose of this study was to assess the efficacy of hyperthermia (42 or 44 degrees C) as a modifier of cis-diamminedichloroplatinum (II) (CDDP) cytotoxicity and platinum incorporation in human pharyngeal carcinoma KB cells. To maximize the interactive effect, we examined the time sequence of high (above 43 degrees C) or low (below 43 degrees C) hyperthermia and CDDP. Within the dose range of CDDP studied, there was a marked synergism between the effects of heating at 44 degrees C and subsequent CDDP exposure for 5 h. Pretreatment at 44 degrees C for 30 min or at 42 degrees C for 4 h enhanced CDDP cytotoxicity more than posttreatment at 44 degrees C for 30 min or at 42 degrees C for 4 h. However, the chemoenhancement ratio of pretreatment at 44 degrees C for 30 min was higher then that of pretreatment at 42 degrees C for 4 h, although the thermal isotoxic dose decreased the cell count to 60% under both conditions. There was a significant increase in CDDP uptake after hyperthermia at 44 degrees C. These results indicate that high hyperthermia effectively enhances subsequent CDDP cytotoxicity in human pharyngeal carcinoma KB cells.
Antineoplastic Agents↗
Effect of dextran on gentamicin-induced ototoxicity.
The effect of low-molecular-weight dextran (DX) on gentamicin (GM)-induced ototoxicity was examined in guinea pigs. GM (100 mg/kg) was administered intramuscularly for 10, 12 and 14 days with or without DX. Cochlear damage was evaluated by compound action potential thresholds and surface preparation after fixation with osmium tetroxide. The percentage of missing outer hair cells was significantly increased by combined administrations of GM with DX. However, there was no significant difference in blood urea nitrogen levels in guinea pigs with or without DX. When aminoglycoside antibiotics and DX are administered together, attention should be paid not only to nephrotoxicity but also to ototoxicity.
Acoustic Stimulation↗
Expression of granulocyte colony-stimulating factor receptor and platelet-derived endothelial cell growth factor in oral and oropharyngeal precancerous lesions.
Epithelial hyperplasia and dysplasia have been diagnosed as precancerous lesions and have been discussed in relationship to carcinogenesis. We analyzed the immunohistochemical expression of granulocyte colony-stimulating factor receptor (G-CSFR) and platelet-derived endothelial cell growth factor (PD-ECGF) in oral and oropharynx; 33 samples of normal epithelium, 28 samples of hyperplasia, 16 samples of dysplasia and 58 samples of squamous cell carcinoma. Also, we examined mean vessel density (MVD) by using CD34 staining and proliferating cell nuclear antigen (PCNA) staining. Dysplasia and head and neck Squamous Cell Carcinoma (SCC) exhibited higher G-CSFR expression and MVD than normal or hyperplastic epithelium (p <0.01). In the PD-ECGF staining, significant differences were found between SCC and normal epithelium, hyperplasia and dysplasia (p<0.001). In dysplasia and hyperplasia, PD-ECGF expression was significantly correlated with PCNA expression (r=0.345, p=0.025), however it was not correlated with the MVD. G-CSFR expression was not correlated with either PCNA or MVD. These results suggest that G-CSFR and PD-ECGF might be concerned with different carcinogenesis pathways of the squamous cells in the oral region and that PD-ECGF may be concerned with epithelial proliferation rather than angiogenesis.
Adult↗
Involvement of intracellular glutathione in induction of apoptosis by cisplatin in a human pharyngeal carcinoma cell line.
We investigated the effect of intracellular glutathione (GSH) levels on apoptosis in KB cells induced by cisplatin (CDDP). The mode of cell death, apoptosis or necrosis, was evaluated by biochemical and morphological criteria. The treatment of KB cells with D,L-buthionine-(S,R)-sulfoximine (BSO, a gamma-glutamyl cysteine synthetase inhibitor) decreased GSH level to 1/7th of that of control cells, and augmented cell death induced by CDDP via a necrotic rather than apoptotic process (the ratio of necrosis to apoptosis; n/a>14). In contrast, treatment with 2-oxothiazolidine-4-carboxylic acid (OTZ, a precursor of cysteine) increased GSH levels 1.7 fold compared with that of untreated cells, inhibited cell death induced by CDDP and switched the mode of cell death from necrosis to apoptosis (n/a<0.8, similar to untreated cells). These results suggest that the GSH level affects the cytotoxicity of CDDP and plays an important role in switching the mode of cell death induced by CDDP.
Antimetabolites, Antineoplastic↗