A variant of KCC2 from patients with febrile seizures impairs neuronal Cl− extrusion and dendritic spine formation

Genetic variation in SLC12A5 which encodes KCC2, the neuron-specific cation-chloride cotransporter that is essential for hyperpolarizing GABAergic signaling and formation of cortical dendritic spines, has not been reported in human disease. Screening of SLC12A5 revealed a co-segregating variant (KCC2-R952H) in an Australian family with febrile seizures. We show that KCC2-R952H reduces neuronal Cl⁻ extrusion and has a compromised ability to induce dendritic spines in vivo and in vitro. Biochemical analyses indicate a reduced surface expression of KCC2-R952H which likely contributes to the functional deficits. Our data suggest that KCC2-R952H is a bona fide susceptibility variant for febrile seizures.     

Technical note: Applicability of tooth cementum annulation to an archaeological population

The use of tooth cementum annulations for age determination has been deemed promising, exhibiting high correlations with chronological age. Despite its apparent potential, to date, the tooth cementum annulations method has been used rarely for estimating ages in archaeological populations. Here we examine the readability of cementum annulations and the consistency of age estimates using a sample of 116 adults from the Iron Gates Gorge Mesolithic/Neolithic series. Our examination of the method pointed to several sources of error that call into question the use of this method for estimating the chronological ages of archaeologically derived dental samples. The poor performance of the method in our analysis might be explained by taphonomic influences, including the effect of chemical and biological agents on dental microstructures. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.     

Identification of novel epithelial stem cell-like cells in human deciduous dental pulp

It is well known that interactions between epithelial components and mesenchymal components are essential for tooth development. Therefore, it has been postulated that both types of stem cells might be involved in the regeneration of dental hard tissues. Recently, mesenchymal dental pulp stem cells that have odontogenic potential were identified from human dental pulp. However, the existence of epithelial cells has never been reported in human dental pulp. In the present study, we isolated and characterized epithelial cell-like cells from human deciduous dental pulp. They had characteristic epithelial morphology and expressed epithelial markers. Moreover, they expressed epithelial stem cell-related genes such as ABCG2, Bmi-1, ΔNp63, and p75. Taken together, our findings suggest that epithelial stem cell-like cells might exist in human deciduous dental pulp and might play a role as an epithelial component for the repair or regeneration of teeth.     

Spine development in Brachionus quadridentatus from an Australian billabong: genetic variation and induction by Asplanchna

Fertilized resting eggs of Australian Brachionus quadridentatus hatched 2–3 days after hydration into females with or, more frequently, without posterior lateral spines. These females then produced clones with short-spined or long-spined phenotypes. Asplanchna girodi induced females from two short-spined clones and one long-spined clone to produce daughters with significantly longer posterior lateral spines. In all clones, there were significant differences in spine development among offspring of mothers within Asplanchna and control treatments. The range of phenotypes reported in one short-spined clone is observed in the billabong and includes much of the variation described for the species, with mehleni (long-spined) phenotypes occurring with Asplanchna. In B. quadridentatus, the ecological significance of long-spined, basic phenotypes, and of the spine-development response to Asplanchna, is unclear. In laboratory cultures, females of all clones were attached to the substratum or water surface, and were safe from Asplanchna; in nature, females are epiphytic and probably rarely susceptible to Asplanchna. Most (96%) resting eggs produced in cultures and kept under culture conditions hatched after a 7-day latent period. This raises questions regarding natural conditions which might prevent hatching and allow accumulation of resting eggs in a sediment egg bank. Hatching of resting eggs in nature may be enhanced in sediments which dry and then become flooded after rains.     

Molecular strategies in the evolution of mammalian dental patterning

The acquisition of masticatory capability by mammals allowed a better processing of food and a consequent increase in the efficiency of nutrients intake by the digestive system. The development of tooth classes and variations in tooth number can be considered intrinsic characteristics of mammalian dentition. These features allowed species to develop specialized dentitions, creating new adaptive zones. Comparative developmental data from knockout mutant mice and human tooth agenesis present new insights on the molecular strategies that permitted rapid phenotypic differentiation, adaptation and speciation of mammalian dentition.     

The uptake of dental services by elderly Germans

Objective: The aim of the study was to assess the uptake of dental services by the old and very old population within the scope of the Berlin Aging Study (Berliner Altersstudie BASE ). Design: A multi‐disciplinary structured interview was performed on 928 subjects, aged from 70 to 103 years of whom 516 persons volunteered to take part in a 14‐session intensive protocol. Six representative study groups were matched for age and gender. Subjects were asked to recall the timing of their most recent dental visit. Data were validated by sending for dental records and compared with all study participants from the multi‐disciplinary intake assessment. Data were related to age group, dental state, dementia and education. Results: Reported last contact with dental services ranged from 2 weeks to 52 years (median 18 months) with a higher time lapse in the study groups aged 85 and older. Dentate subjects had seen their dentist more recently than edentate subjects. Higher education correlated with an increased dental utilisation. Subjective memory on the time lapse since the last dental appointment coincided in 13% of the subjects with available dental records (n=84), was misjudged between one and six months in 55%, and by more than six months in the remainder. Moderately or severely demented subjects who remembered their last dental appointment (n=48 of 70) showed no consistently different utilisation to healthy or mildly demented studs participants. Conclusion: Edentate old and very old subjects show the least frequent utilisation of dental services. Data on motivation and barriers to care are needed to develop strategies to improve the use of dental services and thus promote oral health in late life.     

Regional differences in the morphology of a shrub Damnacanthus indicus: An induced resistance to deer herbivory?

We report here the possibility of an induced resistance of a spiny shrub Damnacanthus indicus against deer herbivory. Six characters of D. indicus were compared between regions with and without deer herbivory on the Boso Peninsula. We found that D. indicus in browsed areas produced smaller leaves, thicker spines, and shorter internode distances between spines than those in unbrowsed areas whereas the length of spines and the angle of a pair of spines did not differ significantly. It is likely that D. indicus shows an induced resistance by producing smaller leaves, and by increasing stoutness of spines and spine density.     

Estimating striae of Retzius periodicity nondestructively using partial counts of perikymata

Accurate age estimations for enamel formation and the timing of enamel hypoplasia have traditionally only been available through histological analyses of dental thin sections, which is a difficult and destructive process. However, an association between striae of Retzius periodicity, crucial for accurate aging, and the total number of striae in imbricational enamel has been reported in the literature. This means periodicity can be estimated nondestructively but is reliant on all perikymata being visible along the crown surface. Therefore, crowns with worn or damaged surfaces may not be able to be assessed, potentially limiting sample sizes. We tested this relationship in a modern New Zealand sample and investigated whether reliable associations might be identified using only partial perikymata counts from the cervical half of the crown. Using mandibular canines (n = 11), the distribution of perikymata per decile was recorded using high definition replica surfaces. Thin sections of the same crowns were used to assess periodicity histologically along with striae of Retzius distributions. A strong correlation between total striae numbers and periodicity was also identified in our sample. Furthermore, we report strong correlations that allow periodicity to be estimated from perikymata counts using only 10% of crown height when certain deciles are used. Based on these findings, we propose a simple matrix that can be developed for nondestructively estimating periodicity based on the range of perikymata counts in the sixth to ninth deciles. Am J Phys Anthropol 154:251–258, 2014. © 2014 Wiley Periodicals, Inc.