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PubMedDate not supplied

Behavioural effects of prenatal metallic mercury inhalation exposure in rats.

The effects of administration by inhalation of metallic mercury vapour (Hg0) to pregnant rats, approximately corresponding to doses of 0.2 mg Hg0/kg/day (high dose) or 0.07 mg Hg0/kg/day (low dose), on the developmental and behavioural repertoire of the offspring were studied. Exposure occurred during days 11-14 plus 17-20 of gestation. The dose levels were selected so as not to induce maternal toxicity. Maturation variables such as surface righting, negative geotaxis, pinna unfolding, and tooth eruption revealed no differences between Hg0-treated offspring and controls. Tests of spontaneous motor activity showed that the Hg0-treated offspring were hypoactive at 3 months of age but hyperactive at 14 months. In spatial learning tasks the prenatally exposed offspring showed retarded acquisition in the radial arm maze but no differences in circular swim maze. A simple test of learning, habituation to a novel environment (activity chambers), indicated a reduced ability to adapt. These data suggest that prenatal exposure to Hg0 vapour results in similar behaviour changes in the offspring as reported for methylmercury.

Administration, Inhalation↗
PubMed1995

Administration of colony stimulating factor-1 to toothless osteopetrotic rats normalizes osteoblast, but not osteoclast, gene expression.

The toothless (tl) osteopetrotic mutation in the rat is characterized by generalized skeletal sclerosis, a severe reduction in the numbers of osteoclasts, monocytes, and macrophages, and absence of tooth eruption. Studies examining gene expression in bone-derived cells of tl rats and their normal littermates have shown that genes related to osteoblast function are aberrantly expressed in tl rats compared to normal littemates. We have previously shown that exogenous administration of colony stimulating factor-1 (CSF-1) to tl rats results in a dramatic reduction of the skeletal sclerosis and significant increases in the number of osteoclasts. Thus, we examined the effects of CSF-1 on osteoblast and osteoclast gene expression in tl rats as demonstrated by Northern blot analysis. While osteoblast-related gene expression as reflected by mRNA levels of alkaline phosphatase, osteocalcin, osteopontin, and type I collagen was normalized, osteoclast-related gene expression, as reflected by mRNA levels of carbonic anhydrase II and tartrate-resistant adenosine triphosphatase, remained significantly lower in CSF-1-treated tl rats compared to untreated normal littermates. Since previous studies have not demonstrated the CSF-1 receptor on osteoblasts, these results suggest that osteoblast abnormalities in tl rats are an effect of the osteopetrotic condition rather than the cause of the disease.

Adenosine Diphosphate↗
PubMed2005

Dental team management for a patient with cleidocranial dysostosis.

Cleidocranial dysostosis is a rare autosomal condition that affects ossification. The dental abnormalities associated with it present a remarkable challenge in orthodontic treatment planning. Early diagnosis is extremely important to give the patient the best treatment options. Patients with cleidocranial dysostosis require a team approach with good communication and cooperation from the patient. Timing of the intervention is critical, and many surgeries might be required. The patient in this report was treated with a team effort that involved several dental specialties to achieve an optimal result.

Child↗
PubMed2005

Subgingival distribution of Campylobacter rectus and Tannerella forsythensis in healthy children with primary dentition.

OBJECTIVE: It is important to know how many subgingival plaque samples should be assayed from a child to ascertain infection with a periodontal pathogen. Plaque samples from several sites may fail to detect some important bacteria if only a limited number of gingival sites are sampled. The purpose of this study was to evaluate the detection of periodontal pathogens in a large number of subgingival sites in the same children in order to determine the number of samples necessary. METHODS: Ten children, aged 4-6 years, with complete primary dentition were enrolled in this study. Plaque samples from the mesio-buccal aspect of each erupted tooth were first collected by gently inserting a sterile paper point for 10s. Purified genomic DNA from all plaque samples was prepared for polymerase chain reaction. The primers for species-specific 16S ribosomal RNA sequence were selected as the target sequence. Standard strains of Campylobacter rectus and Tannerella forsythensis (formerly Bacteroides forsythus) were used as control strains. RESULTS: All subjects were found positive for C. rectus and T. forsythensis with the mean of positive sites at 17.6 +/- 2.4 (range: 12-20 sites) for C. rectus and 9.3 +/- 5.0 (range: 1-19) for T. forsythensis. The mean number of positive sites was 1.7 +/- 0.8 for C. rectus and 6.5 +/- 4.9 for T. forsythensis, with a confidence ratio of 95%. CONCLUSIONS: We concluded that two or more random sites for C. rectus and seven or more random sites for T. forsythensis from children to detect those bacteria at 95% probability.

Aggressive Periodontitis↗
PubMed2006

Scanning electron microscopy of the three different types of cementum in the molar teeth of the guinea pig.

The aim of this study was to observe the three-dimensional distribution and structural characteristics of the three different types of cementum in the molar teeth of guinea pig by means of scanning electron microscopy. Twenty-five 4-week-old male guinea pigs were used in this study. Using decalcified and undecalcified specimens with or without NaOH maceration, we examined the mandibles, maxillae and extracted molars by scanning electron microscopy. Guinea pig molars consist of two longitudinal, deeply folded lamina cores covered by enamel on all surfaces, except the buccal surface of the upper molars and the lingual surface of the lower molars. In the regions without enamel, we observed continuous thin belt-like layers of conventional acellular cementum on the dentin surface. On the enamel-covered surfaces, two different types of coronal cementum were found: small circular islands of coronal cementum called cementum pearls, which were distributed widely at almost regular intervals on the peripheral enamel surface from the apical fifth to the occlusal surface; and cartilage-like cementum, which occupied almost all of the occlusal half of the two longitudinally folded grooves. The present study demonstrated the unique distribution pattern of the three different types of cementum in guinea pig molars. These cementum types may contribute to the requirements for many different functions such as mastication, anchorage and continuous tooth eruption.

Animals↗
PubMed2006

Structural features of incremental line-like striations in mandibular condylar cartilage of c-src-deficient mice.

Mandibular condylar cartilage is sensitive to masticatory force, while mice lacking the c-src gene (c-src-deficient mice) have osteopetrosis and tooth eruption failure. The purpose of this study was to investigate the morphology of the mandibular condyle in these mice, which were maintained with a soft-food diet for 240 days after birth. The condylar head in the c-src-deficient mice showed slight deformity in shape before weaning, but showed remarkable undergrowth after weaning. No significant morphological or histological differences were detected between the mandibular condyle in wild-type mice fed soft food and those fed hard food, indicating that osteopetrosis, as well as abnormal masticatory force, influences the morphology of the mouse mandibular condyle, and that malocclusion rather than dietary consistency may have greater influence. After 70 days, incremental line-like striations consisting of cartilaginous and non-cartilaginous layers were detected in the mandibular condyle of the c-src-deficient mice, but not in the tibial growth plate. Immunostaining of aggrecan, collagen types II and X, and osteopontin was detected in the cartilaginous layers, but not in the non-cartilaginous layers showing collagen type I immunostaining. Chondrocyte lacunae were not eroded in the cartilaginous layers, and complete circumferential mineralisation around the lacunae and impaired osteoclast (chondroclast) function can account for this phenomenon. However, repeated cessation of chondrocyte differentiation may be required to completely explain the formation of the striations. These results indicate that the mandibular condyle in the c-src-deficient mice has unique structural features, adding to its deformity.

Aggrecans↗
PubMed2007

Infant growth, development and tooth emergence patterns: A longitudinal study from birth to 6 years of age.

OBJECTIVE: To test the association of child's growth/development status and socioeconomic variables with dental emergence patterns. DESIGN: A sample of 359 children belonging to a birth cohort of over 5000 children born in 1993 in Pelotas (Brazil) was studied in 1998-1999. Previously trained observers collected birthweight, head circumference at birth, birth height, gestational age, smoking during pregnancy, child's sex and skin colour, height by age at 6 months of age, caries experience in the deciduous teeth, number of emerged teeth at 6 and 12 months of age and emergence stages of the first permanent molars at 6 years of age. Family income, parental educational attainment and anthropometric measurements were collected at children's homes. Poisson regression models were applied in order to select best predictors of pairs of emerged teeth at 6 and 12 months of age and emerged (yes/no) first permanent molars at 6 years of age. RESULTS: Children shorter than 49cm had, on average, less pairs of emerged teeth at 6 months of age. Twelve-month-old children with birth height < or =49cm, presenting height-for-age deficit at 6 months of age and the females also presented less pairs of emerged teeth. Stunted children at 6 months of age were more likely to have non-emerged first upper left and lower right permanent molars at 6 years of age. CONCLUSIONS: Important developmental and nutritional variables at birth and throughout the early life may predict the numbers of emerged teeth children have in their oral cavity.

Birth Weight↗
PubMed2005

Strain-dependent behavioral alterations induced by peripheral interleukin-1 challenge in neonatal mice.

Interleukin-1 (IL-1) is implicated in the pathogenesis of various psychiatric diseases. Peripheral administration of IL-1alpha to neonatal rats induces cognitive and behavioral abnormalities and, therefore, the IL-1alpha-treated animals might serve as a schizophrenia model. The present study assessed genetic influences on IL-1alpha-triggered behavioral impairments, using four different strains of neonatal mice, C3H/He, DBA/2, C57BL/6, and ddY. Neonatal treatments with IL-1alpha differentially altered adult behavioral/cognitive traits in a strain-dependent manner. IL-1alpha treatment decreased prepulse inhibition in DBA/2 and C57BL/6 mice but not in C3H/He and ddY. The treatment increased locomotor activity and startle responses in DBA/2 mice and, conversely, decreased startle responses in C3H/He mice. Behavioral alterations were most remarkable in DBA/2 mice but undetectable in ddY mice. The magnitudes of IL-1alpha actions differed between the brain and periphery and were influenced by mouse genetic background. The IL-1-triggered acute signaling, Ikappa-B degradation, was significant in the frontal cortex of DBA/2 mice and in the hypothalamus of C3H/He mice. An increase in brain p38 MAP kinase phosphorylation was also most marked in the DBA/2 strain. In contrast, subchronic influences of IL-1alpha injections failed to illustrate the strain-dependent behavioral alterations. The peripheral effects of IL-1alpha did not match the strain-dependency of the behavioral alterations, either. Acceleration of tooth eruption and eyelid opening as well as attenuation of weight gain was most marked in C3H/He mice and the induction of serum amyloid protein was the largest in ddY mice. Thus, the peripheral effects of IL-1alpha in DBA/2 mice were relatively inferior to those in the other strains. The present animal study suggests that, in early postnatal development, circulating IL-1alpha trigger brain cytokine signaling and produce distinct influences on later neurobehavioral traits, both depending on genetic background.

Analysis of Variance↗
PubMed2005

New technique for airway correction in neonates with severe Pierre Robin sequence.

To avoid tracheostomy in 11 neonates with severe Pierre Robin sequence, we used a technique of progressive elongation of the mandible (distraction osteogenesis) to correct tongue ptosis, increase pharyngeal airway, and correct micrognathia. All 11 patients were extubated within 3 to 6 days after beginning distraction. At 1 month 54.5% were oral feeders and at 1 year, 100%. Sleep studies were obtained on 7 patients and were normal 1 week to 1 month after operation. Growth was observed to be above the 50th percentile in all patients with no comorbidities. A 5-year clinical follow-up showed the operated mandible to maintain a normal shape and produce an undisturbed tooth eruption sequence. We conclude that distraction osteogenesis to increase the length of the short mandible is an effective alternative to tracheostomy in carefully selected patients.

Airway Obstruction↗
PubMed2005

Structure, attachment, replacement and growth of teeth in bluefish, Pomatomus saltatrix (Linnaeus, 1776), a teleost with deeply socketed teeth.

Tooth replacement poses many questions about development, pattern formation, tooth attachment mechanisms, functional morphology and the evolution of vertebrate dentitions. Although most vertebrate species have polyphyodont dentitions, detailed knowledge of tooth structure and replacement is poor for most groups, particularly actinopterygians. We examined the oral dentition of the bluefish, Pomatomus saltatrix, a pelagic and coastal marine predator, using a sample of 50 individuals. The oral teeth are located on the dentary and premaxillary bones, and we scored each tooth locus in the dentary and premaxillary bones using a four-part functional classification: absent (A), incoming (I), functional (F=fully ankylosed) or eroding (E). The homodont oral teeth of Pomatomus are sharp, deeply socketed and firmly ankylosed to the bone of attachment. Replacement is intraosseus and occurs in alternate tooth loci with long waves of replacement passing from rear to front. The much higher percentage of functional as opposed to eroding teeth suggests that replacement rates are low but that individual teeth are quickly lost once erosion begins. Tooth number increases ontogenetically, ranging from 15-31 dentary teeth and 15-39 premaxillary teeth in the sample studied. Teeth increase in size with every replacement cycle. Remodeling of the attachment bone occurs continuously to accommodate growth. New tooth germs originate from a discontinuous dental lamina and migrate from the lingual (dentary) or labial (premaxillary) epithelium through pores in the bone of attachment into the resorption spaces beneath the existing teeth. Pomatomus shares unique aspects of tooth replacement with barracudas and other scombroids and this supports the interpretation that Pomatomus is more closely related to scombroids than to carangoids.

Animals↗
PubMed2003

Regulation of gene expression of tumour necrosis factor-alpha by protein kinase C in the rat dental follicle.

Tooth eruption requires alveolar bone resorption to form an eruption pathway. Recent studies suggest that tumour necrosis factor-alpha (TNF-alpha) may increase bone resorption by promoting the recruitment of mononuclear cells to the dental follicle to form osteoclasts. Although the major osteoclast burst is seen early postnatally in the rat (day 3), the second round of minor osteoclastogenesis is around postnatal day 10. We have previously reported that TNF-alpha is expressed in the dental follicle of newborn rats with maximum expression at day 9. Such expression is enhanced by IL-1alpha in cultured dental follicle cells. In this report, regulation of TNF-alpha expression by protein kinase C (PKC) was studied both in vitro and in vivo. Incubating dental follicle cells with phorbolmyristate acetate (PMA), a PKC activator, significantly up-regulated TNF-alpha gene expression in a dosage-dependent manner. A PKC specific inhibitor, Gö 6983, abolished this PMA effect on up-regulation of TNF-alpha, but had no effect on IL-1alpha induced expression. TNF-alpha expression was significantly greater after treatment with a combination of PMA and IL-1alpha than in treatments with PMA or IL-1alpha alone, suggesting a synergistic effect on enhancing TNF-alpha expression. These gene expression results were confirmed at the protein level by immunostaining for TNF-alpha in the dental follicle cells. In vivo, injection of PMA into postnatal rats also increased TNF-alpha expression. Thus, PKC up-regulates TNF-alpha expression in dental follicle cells, as does IL-1alpha. However, they appear to utilize different pathways to regulate TNF-alpha expression.

Animals↗
PubMed1978

Ameloblastic fibroma: report of two cases.

Two cases of ameloblastic fibroma are described. One case was a seven-year-old girl, the other a 13-year-old boy. In both cases the tumour was located in the posterior part of the maxilla. Both neoplasms were associated with failure of tooth eruption, in one case a primary molar, in the other case a permanent molar. Local excision was performed in both cases, with a recurrence observed in one case ten months after surgery.

Adolescent↗
PubMed2003

Clinical implications of the oral manifestations of HIV infection in children.

The authors hypothesized that patients infected with HIV at birth would be more vulnerable to oral diseases such as periodontal disease and caries because of their compromised immune system. As a result, they designed a 3-year, longitudinal, case-controlled study that examined HIV-infected children as compared with their normal noninfected household peers. Over 100 HIV-infected participants ages 2 to 15 years were examined at 6-month intervals; no differences were found with respect to caries or periodontal disease prevalence and incidence when the two groups were compared. Although the level of oral disease was similar in the two groups, both groups had more caries than the national norm. Thus, failure to use a control group would have led to the erroneous conclusion that children with HIV infection had a high level of caries. In addition, the authors discovered that tooth eruption was delayed in the HIV-infected group, suggesting some developmental impediment. The HIV-infected group also showed more oral lesions that included candidiasis, linear gingival erythema, and medial rhomboid glossitis. Overall, oral lesions were not valid predictors of the serious consequences of AIDS. The authors speculated, however, that examinations at intervals more frequent than every 6 months might be required to determine whether oral lesions can predict frank AIDS and lowered CD4 cell counts.

Adolescent↗