[A 2-year cohort study on the caries risk assessment of 3-year-old caries-free children using Cariostat caries activity test].

Objective: To evaluate the caries status of a cohort of 3-year-old caries-free children from 2 kindergartens in Beijing in a period of 2 years by using Cariostat caries activity test and to assess the sensitivity and specificity of Cariostat score as a caries risk indicator for caries-free children. Methods: Totally 426 3-year-old caries-free children from 2 kindergartens in Beijing were recruited in the present study. Informed consents were obtained from the children's parents. Dental plaque samples of the children were collected and the Cariostat caries activity tests were conducted at baseline and once a year for 2 years. After two years, the caries status of the cohort children were re-evaluated and the caries incidences amongst children with high (2.0, 2.5, 3.0), medium (1.5) and low (1.0, 0.5, 0.0) levels of Cariostat scores were compared and analyzed. Results: Totally 864 3-year-old children from 2 kindergartens were screened before the study startedand 426 (49.3%) children were caries free. After 2-year follow-up, 312 out of 426 (73.2%) remained in the study. The overall caries incident rate was 46.5% (145/312). The caries incident rate of children with high level of Cariostat scores was 88.9% (88/99), while the caries incident rates of children with medium and low levels of Cariostat scores was 38.7% (36/93) and 17.5% (21/120), respectively. The sensitivity and specificity of the Cariostat test in assessing the caries risk of 3-year-old caries-free children in a period of 2 years were 60.7% and 93.4%, respectively. Conclusions: Cariostat caries activity test can be used as an indicator to predict the caries risk of 3-year-old caries-free children. Comprehensive caries management could be conducted for children in kindergartens based on the caries risk assessment results of caries experience and the Cariostat score.

[Effects of breast-feeding duration, bottle-feeding duration and oral habits on the occlusal characteristics of primary dentition].

OBJECTIVE: To assess the effects of breast-feeding duration, bottle-feeding duration and oral habits on the occlusal characteristics of primary dentition in 3-6-year-old children in Beijing. METHODS: This cross sectional study was conducted via an examination of the occlusal characteristics of 734 children combined with a questionnaire completed by their parents/guardians. The examination was performed by a single, previously calibrated examiner and the following variables were evaluated: presence or absence of deep overbite, open bite, anterior cross bite, posterior cross bite, deep overjet, terminal plane relationship of the second primary molar, primary canine relationship, crowding and spacing. Univariate analysis and multiple Logistic regressions were applied to analyze the associations. RESULTS: It was found that a short duration of breast-feeding (never or ≤6 months) was directly associated with posterior cross bite (OR=3.13, 95%CI=1.11-8.82, P=0.031) and no maxillary space (OR=1.63, 95%CI=1.23-2.98, P=0.038). In children breast-fed for ≤6 months, the probability of developing pacifier-sucking habits was 4 times that for those breast-fed for >6 months (OR=4.21, 95%CI=1.85-9.60, P=0.000 2). The children who were bottle-fed for over 18 months had a 1.45-fold higher risk of nonmesial step occlusion and a 1.43-fold higher risk of class II canine relationship compared with those who were bottle-fed for 6-18 months. Non-nutritive sucking habits were also found to affect occlusion: a prolonged digit-sucking habit increased the probability of an anterior open bite, while a pacifier-sucking habit was associated with excessive overjet and absence of lower arch developmental space. Tongue-thrust habit was associated with anterior open bite (OR=4.21, 95%CI=1.85-9.60, P=0.000 2) and posterior cross bite (OR=7.24, 95%CI=1.30-40.13, P=0.024). Lower lip sucking habit was associated with deep overjet and had a negative association with class III canine relationship. Unilateral chewing was associated with spacing in mandibular (OR=1.57, 95%CI=1.03-2.41, P=0.037). Mouth breathing was associated with chronic rhinitis and adenoidal hypertrophy and had an association with spacing in maxillary. The chi-square test did not indicate a statistically significant association between upper lip sucking habit and any occlusal characteristics. CONCLUSION: Breast-feeding duration was shown to be associated with the prevalence of posterior crossbite, or no maxillary space in the deciduous dentition and development of a pacifier-sucking habit. Children who had a longer duration of bottle-feeding were more likely to develop class II canine relationship. Children who had an oral habit were more likely to develop abnormal occlusal characteristics.

PTCH germline mutations in Chinese nevoid basal cell carcinoma syndrome patients.

OBJECTIVES: PTCH, the human homologue of the Drosophila segment polarity gene, patched, has been identified as the gene responsible for nevoid basal cell carcinoma syndrome. The aim of this study was to investigate PTCH gene mutation in Chinese patients with nevoid basal cell carcinoma syndrome. MATERIALS AND METHODS: DNA was isolated from both odontogenic keratocyst tissue and peripheral blood of five patients with syndrome and one patient with only multiple odontogenic keratocysts, and mutational analysis of the PTCH gene performed by direct sequencing after amplification of all 23 exons by polymerase chain reaction (PCR). RESULTS: A previously reported germline mutation (c.2619C>A) was identified in two familial cases involving the mother and the daughter, with the mother also carrying a novel somatic mutation (c.361_362insGAGC). Three novel germline PTCH mutations (c.1338_1339insGCG, c.331delG and c.1939A>T) were detected in three unrelated patients with syndrome. The patient with multiple odontogenic keratocysts who failed to fulfill the diagnostic criteria of the syndrome also carried a novel germline mutation (c.317T>G). CONCLUSION: The frequent germline PTCH mutations detected in our series provide further evidence for the crucial role of PTCH in the pathogenesis of nevoid basal cell carcinoma syndrome in Chinese.

Dynamic regulation of the siphon withdrawal reflex of Aplysia californica in response to changes in the ambient tactile environment.

The state of an animal's environment can be viewed as a source of information that can be used to regulate both ongoing and future behavior. The present work examined how the ambient environment can regulate the Aplysia siphon withdrawal reflex (SWR) by changing the environment between calm and turbulent. Results indicate that the SWR is dynamically regulated on the basis of variations in external conditions, so that responsiveness (measured as both reflex duration and threshold) is matched to the state of the environment. Prior exposure to a noxious stimulus (tailshock) has selective effects on this regulation, suggesting the existence of multiple regulatory mechanisms. Further, neurophysiological correlates to behavioral observations were measured in sensory and motor neurons. This will allow for a detailed cellular analysis of environmental information-processing in this system.

Cloning and characterization of human inducible nitric oxide synthase splice variants: a domain, encoded by exons 8 and 9, is critical for dimerization.

The inducible nitric oxide synthase (iNOS) contains an amino-terminal oxygenase domain, a carboxy-terminal reductase domain, and an intervening calmodulin-binding region. For the synthesis of nitric oxide (NO), iNOS is active as a homodimer. The human iNOS mRNA is subject to alternative splicing, including deletion of exons 8 and 9 that encode amino acids 242-335 of the oxygenase domain. In this study, iNOS8(-)9(-) and full-length iNOS (iNOSFL) were cloned from bronchial epithelial cells. Expression of iNOS8(-)9(-) in 293 cell line resulted in generation of iNOS8(-)9(-) mRNA and protein but did not lead to NO production. In contrast to iNOSFL, iNOS8(-)9(-) did not form dimers. Similar to iNOSFL, iNOS8(-)9(-) exhibited NADPH-diaphorase activity and contained tightly bound calmodulin, indicating that the reductase and calmodulin-binding domains were functional. To identify sequences in exons 8 and 9 that are critical for dimerization, iNOSFL was used to construct 12 mutants, each with deletion of eight residues in the region encoded by exons 8 and 9. In addition, two "control" iNOS deletion mutants were synthesized, lacking either residues 45-52 of the oxygenase domain or residues 1131-1138 of the reductase domain. Whereas both control deletion mutants generated NO and formed dimers, none of the 12 other mutants formed dimers or generated NO. The region encoded by exons 8 and 9 is critical for iNOS dimer formation and NO production but not for reductase activity. This region could be a potential target for therapeutic interventions aimed at inhibiting iNOS dimerization and hence NO synthesis.

Polycyclic aromatic hydrocarbons decrease intracellular glutathione levels in the A20.1 murine B cell lymphoma.

Previous studies in this laboratory have shown that polycyclic aromatic hydrocarbons (PAHs) inhibit lymphocyte activation and alter intracellular Ca2+ homeostasis. Other investigators have demonstrated that intracellular Ca2+ may increase in lymphocytes following exposure to chemical oxidants or ionizing radiation. Cellular oxidants produce both a rise in intracellular Ca2+ and a decrease in intracellular levels of glutathione (GSH) in numerous cells and tissues. Therefore, the purpose of the present study was to determine whether PAHs alter intracellular levels of glutathione in lymphocytes. Using different, well-established glutathione assays, it was demonstrated in the A20.1 murine B lymphoma that PAHs induce a transient decrease in intracellular glutathione. A 10-25% decrease in reduced GSH was produced by benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, benz(a)anthracene, and anthracene within 2-4 hr of exposure. Benzo(e)pyrene did not alter intracellular levels of glutathione in A20.1 cells. We conclude that glutathione depletion may contribute to cell injury in lymphocytes exposed to PAHs.

An epidemiological study on farmer's lung among hay grinders in Dafeng County.

This article reports on an epidemiological survey of the presence of farmer's lung among 1054 farmers who grind moldy hay. The prevalence was 8.3-11.4%. The main pathogen was Thermoactinomyces vulgaris. The factors which influenced farmer's lung were the moldy state of the hay and the dust concentration. The epidemiological features of farmer's lung are analyzed and discussed and certain preventive measures are suggested.