[Analysis of the risk factors of radiation-induced caries in patients with head and neck cancer].

OBJECTIVE: This study aimed to evaluate the risk factors of radiation-induced caries by using a multiple linear regression equation and to provide the basis for the effective prevention of radioactive caries. METHODS: A total of 166 patients with head and neck cancer who underwent radiotherapy were selected as subjects. The number of decayed, missing or filled surfaces were recorded. Questionnaire contents included age, sex, radiation dose, and radiotherapy techniques. Multiple stepwise regression analyses were performed to identify the risk factors of radiation-induced caries. RESULTS: Multiple stepwise regression analyses indicated that the main risk factors of radiation-induced caries were plaque index, radiotherapy techniques, time after radiotherapy, and radiotherapy dose. CONCLUSIONS: The awareness of dental care and caries treatment should be improved to reduce the occurrence of radiation-induced caries in patients with head and neck cancer. In addition, intensity modulated radiation therapy should be employed to decrease the radiation exposure dose received by teeth.

Mummified Oligocene fruits of Schima (Theaceae) and their systematic and biogeographic implications.

The genus Schima includes about 20 species and is distributed only in southern China and adjacent areas of Asia. The previous molecular phylogenetic analysis suggested Schima is in the tribe Gordoniae, along with Gordonia and Franklinia. However, because few fossils have been reported, the biogeographic origin of Schima is still poorly known. In this paper mummified fossil fruits of Schima are described from the upper Oligocene Yongning Formation of the Nanning Basin, Guangxi, South China. In gross morphology, the new fossil species, Schima kwangsiensis, is similar to the extant S. superba by its pentacarpellate, loculicidally dehiscent capsules, 5 imbricate sepals, pedicels with bracteoles and marginally winged seeds. Due to its excellent preservation, the new species may provide sufficient details for understanding the early evolutionary and phytogeographic history of the genus. Morphological clustering analysis shows that the new fossil species is closely related to two extant species (S. wallichii and S. superba) in the genus, implying that they may belong to an ancient taxon that occurs earlier than the others. More importantly, this discovery represents the earliest record of this genus in Asia and it explicitly moves the fossil record back to the late Oligocene in this region.

Cyp2c19 genotype and omeprazole hydroxylation phenotype in Chinese Li population.

1. CYP2C19 is a polymorphism of cytochrome P450, which is responsible for the metabolism of many drugs. The genetic polymorphism shows interethnic variation and it has been demonstrated that the frequency of poor metabolizers (PM) and the distribution of alleles of CYP2C19 vary among Chinese ethnic nationalities. The aim of the present study was to investigate the incidence of CYP2C19 polymorphism in the Chinese Li population. 2. One hundred and sixty-five unrelated healthy Li subjects were identified with respect to CYP2C19 by genotype and phenotype analysis. A polymerase chain reaction-restriction fragment length polymorphism method was performed for genotyping. The plasma concentrations of omeprazole and 5-hydroxyomeprazole were assayed by reversed-phase high-performance liquid chromatography and the omeprazole hydroxylation index (HI) was determined. 3. The frequency distribution of omeprazole HI is bimodal and the antimode for HI was estimated to be 5.6. The prevalence of phenotypic PM in the Li population was 16.6% (13.7-19.5; 95% CI). Genotype analysis revealed that the frequencies of the CYP2C19*1, *2 and *3 alleles in the Li population were 0.617 (0.590-0.644; 95% CI), 0.353 (0.327-0.379; 95% CI) and 0.031 (0.021-0.041; 95% CI), respectively. The frequency of genotypic PM was 14.7% (11.9-17.5; 95% CI), which almost agreed with the frequency of phenotypic PM. Omeprazole HI was significantly different among the different genotype groups (P < 0.05). 4. The present study revealed that the incidence of the CYP2C19*1, *2 and *3 alleles in Chinese Li population is different to that in other ethnic populations of China. There was an obvious relationship between CYP2C19 genotype and omeprazole hydroxylation phenotype, and about 90% of phenotypic PM can be explained by the CYP2C19*2 and *3 alleles.