Tooth eruption: Theories and facts

The mechanisms of tooth eruption (i.e., the answer to the question of how and why teeth erupt) has been a matter of long historical debate. This review focuses on human and other mammalian teeth with a time- and spacewise limited period of eruption and analyzes recent observations and experimental data on dogs, rats, primates, and humans in a framework of basic biological parameters to formulate a guiding theory of tooth eruption. Acknowledging basic parameters (i.e., that teeth move in three-dimensional space, erupt with varying speed, and arrive at a functional position that in inheritable) eliminates a number of previously held theories and favors those that accommodate basic parameters, such as alveolar bone remodeling in association with root elongation, with possible correction factors in the form of cementum apposition and periodontal ligament formation. We have critically analyzed, summarized, and integrated recent findings associated with preeruptive movements of developing teeth, the intraosseous stage of premolar eruption in dogs, molar eruption in rodents, and premolar and molar eruption in primates. The variable speeds of eruption are particularly important. We conclude with basic principles of tooth eruption—that is, the type of signals generated by the dental follicle proper, the conditions under which teeth are moved and the clinical understanding to be derived from this knowledge. © 1996 Wiley-Liss, Inc.     

Inhibitory neuronal changes following a mixed diffuse-focal model of traumatic brain injury

Traumatic brain injury (TBI) can result in excitation: inhibition imbalance, as well as a range of chronic neurological deficits. However, how TBI affects different interneurons, and how this relates to behavioral abnormalities, remains poorly understood. This study examined the effects of a mixed diffuse-focal model of TBI, the lateral fluid percussion injury (LFPI), on interneurons, 8 weeks post-TBI in rats. Brains were labeled with antibodies against calbindin, parvalbumin, calretinin, neuropeptide Y, and somatostatin, and the number of interneurons were assessed in the cortex and hippocampus following LFPI. LFPI caused a reduction in the numbers of interneurons mediating both perisomatic and dendritic inhibition in the somatosensory cortex. In hippocampus, there were heterogenous changes in the number of interneurons while motor cortex, showed no obvious loss in any of the subsets of interneurons after TBI. In parallel to the investigations of changes in the number of interneurons, we also investigated the long-term behavioral consequences of LFPI. Behaviorally, rats given an LFPI displayed transient reduction in performance in motor tasks and were significantly impaired in reversal learning in the water maze task post-TBI. We also report here progressive neurodegeneration in cortex and hippocampus indicated by Fluoro-Jade C in the different brain areas examined after injury. Our findings suggest differential vulnerability of inhibitory neurons to LFPI in the different brain areas examined after injury. These data will aid in evaluation of new treatments for TBI and help target specific neuronal subtypes as a function of injury time and type.     

A roleplaying test for the assessment of interpresonal styles

The Improvisation Test for Individuals (Impro-I) consists of 12 roleplays that represent a variety of interpersonal situations. Performance is evaluated by observers. Forty-seven Ss were examined by two test teams in order to evaluate the reactions of the Ss to the roleplays and to determine interrater reliabilities. Ss found the roleplays generally realistic and their own performances lifelike. Interrater reliabilities were moderate to high.     

Increased extracellular matrix density decreases MCF10A breast cell acinus formation in 3D culture conditions

The extracellular matrix (ECM) contributes to the generation and dynamic of normal breast tissue, in particular to the generation of polarized acinar and ductal structures. In vitro 3D culture conditions, including variations in the composition of the ECM, have been shown to directly influence the formation and organization of acinus‐like and duct‐like structures. Furthermore, the density of the ECM appears to also play a role in the normal mammary tissue and tumour formation. Here we show that the density of the ECM directly influences the number, organization and function of breast acini. Briefly, non‐malignant human breast MCF10A cells were incubated in increasing densities of a Matrigel®–collagen I matrix. Elastic moduli near and distant to the acinus structures were measured by atomic force microscopy, and the number of acinus structures was determined. Immunochemistry was used to investigate the expression levels of E‐cadherin, laminin, matrix metalloproteinase‐14 and ß‐casein in MCF10A cells. The modulus of the ECM was significantly increased near the acinus structures and the number of acinus structures decreased with the increase in Matrigel–collagen I density. As evaluated by the expression of laminin, the organization of the acinus structures present was altered as the density of the ECM increased. Increases in both E‐cadherin and MMP14 expression by MCF10A cells as ECM density increased were also observed. In contrast, MCF10A cells expressed lower ß‐casein levels as the ECM density increased. Taken together, these observations highlight the key role of ECM density in modulating the number, organization and function of breast acini. Copyright © 2013 John Wiley & Sons, Ltd.     

CHALLENGING BEHAVIOUR AND COMMUNITY SERVICES: 5. Structuring staff and client activity

This paper describes important programmatic components of small, community based, residential services for people with severe mental handicaps and challenging behaviours. The approach described advocates the use of procedures to plan staff activity in considerable detail in order to achieve goals in the areas of supporting people's engagement in functional, age-appropriate activities and managing inappropriate behaviour.     

The Use of the Autism Diagnostic Interview-Revised with a Latino Population of Adolescents and Adults with Autism

Research shows that Latinos are less likely to be diagnosed with autism than their non-Latino counterparts. One factor that may contribute to these differences is that autism diagnostic instruments have not been adapted for the Latino population. The present study compared scores from the Autism Diagnostic Interview-Revised for two groups: 48 Latino adolescents and adults with autism and a matched sample of 96 non-Latino Whites. There were no significant differences between the two groups in total impairments in social reciprocity or communication. However, lower levels of restrictive-and-repetitive behaviors were found among Latino adolescents and adults with autism compared to Whites. Findings suggest that there may be cultural equivalency in some domains, but others may warrant further exploration.