Seventy-six healthy adults underwent magnetic resonance imaging (1.5 T) to investigate the effects of age on regional cerebral volumes and on the frequency and severity of cortical atrophy, lateral ventricular enlargement, and subcortical hyperintensity. Increasing age was associated with (1) decreasing volumes of the cerebral hemispheres (0.23% per year), the frontal lobes (0.55% per year), the temporal lobes (0.28% per year), and the amygdala-hippocampal complex (0.30% per year); (2) increasing volumes of the third ventricle (2.8% per year) and the lateral ventricles (3.2% per year); and (3) increasing odds of cortical atrophy (8.9% per year), lateral ventricular enlargement (7.7% per year), and subcortical hyperintensity in the deep white matter (6.3% per year) and the pons (8.1% per year). Many elderly subjects did not exhibit cortical atrophy or lateral ventricular enlargement, however, indicating that such changes are not inevitable consequences of advancing age. These data should provide a useful clinical context within which to interpret changes in regional brain size associated with "abnormal" aging.

This study used atomic force microscopy (AFM) to probe the local cell-surface interactions associated with the glucan polymers of Streptococcus mutans, the macromolecules most commonly attributed to the virulence of this microbe. In situ force spectroscopy was used to quantitatively probe and correlate cell-surface adhesion and dynamics with S. mutans UA140 wild-type and five glucosyltransferase mutants. Adhesion between the tooth surface and S. mutans is largely mediated by glucan production from sucrose via three glucosyltransferases (Gtfs; GtfB, GtfC and GtfD). To monitor the contribution of these particular Gtfs, isogenic mutants of S. mutans were constructed by specific gene inactivation and compared to the wild-type under sucrose and non-sucrose conditions. We report direct measurement of the mechanical properties associated with glucan macromolecules demonstrating that the local adhesion strength increases in a time-dependent process, with a decrease in the average number of rupture events. This finding suggests that S. mutans attaches mainly through glucans to surfaces in the presence of sucrose. In addition, a possible role of the Gtf proteins in sucrose-independent attachment is supported by the decreased adhesion properties of the GtfBCD mutant compared to the wild-type.

selectivity for S. mutans , and not other oral bacteria, and affects targeted bacteria within seconds of contact. Methods: In the present study, we evaluated C16G2 for clinical utility in vitro, followed by a pilot efficacy study to examine the impact of a 0.04% (w/v) C16G2 rinse in an intra-oral remineralization/demineralization model. Results and Conclusions: C16G2 rinse usage was associated with reductions in plaque and salivary S. mutans , lactic acid production, and enamel demineralization. The impact on total plaque bacteria was minimal. These results suggest that C16G2 is effective against S. mutans in vivo and should be evaluated further in the clinic. Copyright © 2011 S. Karger AG, Basel Dental caries is a chronic infection that affects populations worldwide. In the United States alone, health care costs associated with treating dental caries have topped 64 billion USD annually [Evans and Kleinman, 2000; Anonymous, 2008]. In the developing world, dental caries is more prevalent, especially among pediatric patients, Key WordsAntimicrobial ؒ Antimicrobial peptide ؒ Caries ؒ Demineralization ؒ Dental plaque ؒ Lactic acid ؒ Mouth rinse ؒ Oral therapeutic ؒ Selective antibiotic ؒ Selective therapeutic ؒ Specifically targeted antimicrobial peptide ؒ Streptococcus mutans ؒ Targeted antimicrobial Abstract Background/Aims: Streptococcus mutans , the major etiological agent of dental caries, has a measurable impact on domestic and global health care costs. Though persistent in the oral cavity despite conventional oral hygiene, S. mutans can be excluded from intact oral biofilms through competitive exclusion by other microorganisms. This suggests that therapies capable of selectively eliminating S. mutans while limiting the damage to the normal oral flora might be effective long-term interventions to fight cariogenesis. To meet this challenge, we designed C16G2, a novel synthetic specifically targeted antimicrobial peptide with specificity for S. mutans . C16G2 consists of a S. mutans -selective 'targeting region' comprised of a fragment from S. mutans competence stimulation peptide (CSP) conjoined to a 'killing region' consisting of a broad-spectrum antimicrobial peptide (G2). In vitro studies have indicated that C16G2 has robust efficacy and

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Oral biofilms are multispecies communities, and in their nascent stages of development, numerous bacterial species engage in interspecies interactions. Better insight into the spatial relationship between different species and how species diversity increases over time can guide our understanding of the role of interspecies interactions in the development of the biofilms. Quantum dots (QD) are semiconductor nanocrystals and have emerged as a promising tool for labeling and detection of bacteria. We sought to apply QD-based primary immunofluorescence for labeling of bacterial cells with in vitro and in vivo biofilms and to compare this approach with the fluorophore-based primary immunofluorescence approach we have used previously. To investigate QD-based primary immunofluorescence as the means to detect distinct targets with single-cell resolution, we conjugated polyclonal and monoclonal antibodies to the QD surface. We also conducted simultaneous QD conjugate-based and fluorophore conjugate-based immunofluorescence and showed that these conjugates were complementary tools in immunofluorescence applications. Planktonic and biofilm cells were labeled effectively by considering two factors: the final nanomolar concentration of QD conjugate and the amount of antibody conjugated to the QD, which we define as the degree of labeling. These advances in the application of QD-based immunofluorescence for the study of biofilms in vitro and in vivo will help to define bacterial community architecture and to facilitate investigations of interactions between bacterial species in these communities.Quantum dots (QD) are semiconductor nanocrystals which have been coupled to biomolecules, such as transferrin (4, 18), immunoglobulin G (IgG) (4), biotin (3), streptavidin (23, 42), avidin (11, 16), nucleic acids (8, 38, 39), peptides (2), serotonin (31), adenine(17), adenine monophosphate (17), and wheat germ agglutinin (17, 18). These conjugates are luminescent probes that bind with specificity and sensitivity to a variety of targets (IgG, antigens, glycoproteins, nucleic acid sequences, and receptors). Unlike traditional fluorophore fluorescence, QD luminescence is photostable and size tunable, with narrow, symmetric emission spectra and broad continuous excitation, allowing excitation of multiple QD with a single wavelength (3,4,12,18,42). These properties make QD very attractive luminescent labels for biological applications.In the last decade, significant advances have been made with eukaryotic applications of QD conjugates; however, bacteriological applications are few. The first use of QD for bacterial labeling was reported by Kloepfer et al. in 2003 (18). QD have since been used for labeling, detection, and quantification of Mycobacterium bovis bacillus Calmette-Guérin (25), Escherichia coli O157:H7 (33), and Salmonella enterica serovar Typhimurium (40) and recently for the simultaneous detection of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium (41). The limit and speed for QD-based detection of pathoge...