Undecalcified mature enamel sections were used to observe the sequence of ultrastructural changes of enamel crystals and Streptococcus mutans biofilm in the early stages of caries. Human enamel blocks were incubated from 1 to 7 days with S. mutans suspension, and the pH of biofilm was measured. They were processed for light microscopic and transmission electron microscopy observations, and the number of bacteria located in the area adjacent to enamel surface counted. It was observed that the pH of the biofilm dropped to 4, after 1-day of incubation and the S. mutans number increased until 4-day. Round shaped enamel crystals were observed in the 2-day specimens and from the 4-day, images of crystals showing defects and perforations were visualized, becoming more defective along the incubation days. The length of time that the enamel was exposed to biofilm was the main factor for enamel crystals demineralization. Current in vitro caries induction system could standardize timerelated changes of the property of Streptococcus mutans biofilm and its relation to enamel crystals demineralization at the ultrastructural level, and thus provide a useful model for the evaluation of the effects of various anti-cariogenic agents.

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Biochemical modulation of 5-fluorouracil (5-FU) has been verified the evidence of significant improvement of survival and quality of life in patients with advanced colorectal carcinoma. We investigated the therapeutic and adverse drug reaction of intensive chemotherapy using cis-platin (CDDP), 5-FU and dl-leucovorin (LV) (PFL-therapy), which may be producing dual biochemical modulation effect of 5-FU for advanced colorectal carcinoma. Administration schedule was 13 mg/m² of CDDP, 300 mg/m² of 5-FU, and 30 mg/body of dl-LV for 5 consecutive days. This regimen was repeated at 3-week intervals in hospital. Sixteen patients were enrolled in this study, most of whom had a history of previous chemotherapy as adjuvant treatment, and the response rate was 25%, with four patients having "partial response" and eight "no change". In respect to performance status, 46% of patients who completed the protocol were markedly improved in spite of their poor performance status before treatment. Moreover, when patients were classified into two groups based on changes of the serum level of CEA, "responder in CEA level" showed better prognosis than "non-responder in CEA level". Major toxicifies were nausea, hyperglycemia and neutropenia. Three patients experienced Grade 4 hematological side effect, but these complications resolved quickly in all patients except for one patient. PFL-therapy is effective for advanced colorectal cancer with large tumor burden and showed the same prognostic result as the American and European trials in spite of smaller number of treatment cycles and a history of previous chemotherapy. We will be able to demonstrate the usefulness of this regimen for Japanese patients with advanced colorectal cancers after adding new cases to the present report.

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The purpose of this study was to investigate the expression of PG mRNA in human temporomandibular joint (TMJ) disks from patients with temporomandibular disorders (TMD). Total RNA was isolated from the TMJ disks. All patients had undergone diskectomy under general anethesia. RT-PCR was performed using primers for the proteoglycans, aggrecan and decorin. On electrophoresis of a lysate of human TMJ disks, decorin was recognized in each sample. In the calcified part of the disk which we recognized visually, aggrecan was also recognized. These results suggest that TMJ disks contain decorin, and are fibrous tissue. If the disk was subjected to excessive compression in addition to tension, cells similar to chondrocytes and expression of aggrecan was induced. Calcification would be initiated in the part of the disk experiencing the increased compression.

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