Search

The ingestion of ethanol during pregnancy has a number of deleterious consequences for the unborn offspring, producing structural and functional deficits that affect the brain and many other organs into adulthood. The hippocampus is a brain area that is particularly sensitive to ethanol's adverse effects. In a previous study we showed that voluntary exercise can ameliorate deficits in long-term potentiation and behavior that occur following prenatal ethanol exposure (Eur J Neurosci, 2005, 21, 1719-1726). In the present study, we investigated the effects of prenatal ethanol exposure on neurogenesis in adulthood, and tested the hypothesis that voluntary exercise would ameliorate any deficits observed. Sprague-Dawley females were administered one of three diets throughout gestation: (i) ethanol (E), a liquid diet containing 36.5% ethanol-derived calories; (ii) pair-fed (PF), a liquid control diet, with maltose-dextrin isocalorically substituted for ethanol, in the amount consumed by an E partner (g/kg body wt/day of gestation); and (iii) ad-libitum-fed control (C), normal laboratory chow and water, ad libitum. The offspring were housed individually at postnatal day (PND) 35, and at PND 50 were randomly assigned to cages either with or without an exercise wheel. BrdU (200 mg/kg, I.P.) was injected on PND 57, and animals terminated either 24 h (proliferation) or 4 weeks (neurogenesis) later. Our results demonstrate that prenatal ethanol exposure significantly decreases both cell proliferation and neurogenesis in the adult dentate gyrus. Animals in the PF condition also showed reduced neurogenesis. In contrast, all animals that engaged in voluntary exercise showed a significant increase in cell proliferation and neurogenesis. These results indicate that prenatal ethanol exposure can suppress both cell proliferation and neurogenesis, and that these effects may be, at least in part, nutritionally mediated. Importantly, voluntary exercise appears to have beneficial effects for these long-lasting deficits in hippocampal volume and cell number that have been observed in animals exposed to ethanol in utero., ((c) 2006 Wiley-Liss, Inc.)

Environmental enrichment (EE) and voluntary exercise (VEx) have consistently been shown to increase adult hippocampal neurogenesis and improve spatial learning ability. Although it appears that these two manipulations are equivalent in this regard, evidence exists that EE and VEx affect different phases of the neurogenic process in distinct ways. We review the data suggesting that EE increases the likelihood of survival of new cells, whereas VEx increases the level of proliferation of progenitor cells. We then outline the factors that may mediate these relationships. Finally, we provide a model showing that VEx leads to the convergence of key somatic and cerebral factors in the dentate gyrus (DG) to induce cell proliferation. Although insufficient evidence exists to provide a similar model for EE, we suggest that EE-induced cell survival in the DG involves cortical restructuring as a means of promoting survival. We conclude that EE and VEx lead to an increase in overall hippocampal neurogenesis via dissociable pathways, and should therefore, be considered distinct interventions with regard to hippocampal plasticity and associated behaviors., ((c) 2006 Wiley-Liss, Inc.)

This research explored the differential association of everyday stress with the episodic memory test performances of young, mid-life, and older adults. Participants included 98 community-dwelling adults ranging in age from 19-89 years. Everyday stress was assessed via the Perceived Stress Scale and the Elder Life Stress Inventory. A brief battery of episodic memory tasks was administered which included tests of Logical Memory, Verbal Paired Associates, Digit Symbol Substitution, and Digit Symbol Incidental Learning. Results suggest that everyday hassles and irritations as well as the accumulation of challenging life events may exacerbate age-related decline on episodic memory tests that require greater executive resources and more integrated and elaborative processing. The functional relationship between affective status and risk for dementia is discussed, and consideration of individual differences in everyday stress is suggested so as to allow more sensitive interpretation of episodic memory tests commonly used to discern mild cognitive impairment.

Statement of Problem: Several methods have been used to determine the surface characteristics of resin composites in vivo and compare composite wear rates with enamel wear rates., Purpose: This pilot study describes the surface characteristics of resin composites and the wear of resin composites and enamel during 1 year of in vivo service., Material and Methods: A single Class II posterior resin composite restoration (Z100) was placed in 10 patients. Restored teeth and unrestored adjacent control teeth were measured for wear 4 times within the first year. A null point contact stylus profiler and fitting software were used to measure epoxy casts. Maximum depth of wear, average depth of wear, and characteristics of the restoration margin were determined. Paired t tests were used to compare the control and restored teeth, and ANOVA was used to assess the progression of wear over time (P<.05)., Results: After 1 year, maximum depth of wear over the entire preparation region was on average 204.8 microm (+/- 129.8), significantly greater than the 36. 8 microm (+/- 10.1) average maximum depth of wear of enamel at occlusal contact areas on control teeth (P=.009). Maximum depth of wear progressed over time (P=.009). Fracture of excess composite, commonly called flash fracture, occurred in 50% of the restored teeth extending over the preparation margin., Conclusion: Composite restorations wore significantly faster than enamel contact areas on control teeth. Also of concern were the marginal flash fractures that could facilitate secondary caries.

An in-vitro radiographic study of human teeth was performed in order to evaluate the ability of radiographs to determine the location of the apical foramen. The tip of an endodontic file was positioned at the apical foramen of each canal in 117 extracted human teeth (213 canals) and in 56 teeth (92 canals) still within the alveolus of dried jaw specimens. Parallel radiographs were taken in a bucco-lingual plane of all teeth. The tip of the instrument appeared to be at the root surface (apical foramen) in 82 per cent of canals. There was no significant difference in results between the teeth radiographed in the alveolus of dried jaw specimens and extracted teeth when the radiographs were evaluated under a stereomicroscope.

An in vitro dye leakage study was performed to evaluate the sealing ability of the following retrofilling materials: high- and low-temperature injectable thermoplasticized gutta-percha with and without sealer, a glass ionomer cement, and amalgam with and without varnish. The roots of 105 extracted human maxillary anterior teeth were instrumented and obturated with single cones of gutta-percha and sealer. The apical 3 mm of the roots were then resected and 2-mm deep retrograde preparations were prepared. Each root was then randomly placed into one of seven groups and retrofilled with one of the test materials. After 72 h in India ink, the roots were cleared and evaluated for leakage using a stereomicroscope. Statistical analysis of the results indicated that injectable high-temperature gutta-percha without sealer demonstrated significantly more leakage than the other materials. There were no significant differences in leakage among the other evaluated materials.

The increasing reports of antibiotic-resistant bacteria and the introduction of new antibiotics have resulted in a change in prescribing antibiotics in many dental offices. The purpose of this article is to provide a rationale for selecting the appropriate antibiotic for odontogenic infections and to review the basic concepts of antibiotic therapy.

Ninety extracted human teeth with a single canal and a large patent foramen were obturated by one of three methods after placement of a master gutta-percha cone and sealer. The apical seals were evaluated by ink penetration. Statistical analysis of the results indicated that the group obturated with the high-temperature injected thermoplasticized technique (Obtura) had an apical seal comparable to the group obturated by lateral condensation. The group obturated with the low-temperature injected thermoplasticized technique (Ultrafil) produced an apical seal significantly better than the other two techniques.