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Selected Abstracts

Fluorescence-controlled Er:YAG laser for caries removal in permanent teeth: a randomized clinical trial

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2008
Henrik Dommisch
The aim of this randomized clinical study was to compare the efficacy of a fluorescence-controlled erbium-loaded yttrium aluminum garnet (Er:YAG) laser with conventional bur treatment for caries therapy in adults. Twenty-six patients with 102 carious lesions were treated using either the Er:YAG laser, at threshold levels of 7, 8, 9, and 10 [U], or rotary burs. Both techniques were applied to each lesion at separate locations. After treatment, dentine samples were obtained using a carbide bur. The viable counts of Streptococcus mutans (SM) and lactobacilli (LB) [expressed as colony-forming units (log10 CFUs)], treatment time, pain, vibration, and sound intensity were determined. The median numbers of CFUs for SM and LB were not statistically different between laser and bur treatment at threshold levels 7 and 8 [U]. At threshold levels 9 and 10 [U], the median number of CFUs for LB [1.11 (range: 0.00,2.04)] were significantly higher following laser treatment than following bur treatment [0.30 (range: 0.00,0.60)]. The results indicate that treatment with a fluorescence-controlled Er:YAG laser at threshold levels of 7 and 8 removed caries to a level similar to that achieved using conventional bur treatment, with clinically irrelevant amounts of remaining bacteria. Although more time consuming, laser treatment provided higher patient comfort than bur treatment. [source]

Simulated Computer-Mediated/Video-Interactive Distance Learning: A Test of Motivation, Interaction Satisfaction, Delivery, Learning & Perceived Effectiveness

JOURNAL OF COMPUTER-MEDIATED COMMUNICATION, Issue 3 2001
Ruth Guzley
This paper reports on an innovative, computer-mediated, educational technology application in a simulated distance learning environment. As an initial evaluation, real student groups completed an entire university course using this state-of-the-art, two-way synchronous audio/visual communication technology, Distributed Tutored Video Instruction (DTVI). The study reported here explored student perceptions of a simulated distance learning environment using the system. The learning environment was characterized by videotaped lectures by the course instructor, delivered in computer-mediated small group settings. Six separate groups made up of six to eight students and a facilitator were studied. Group members were in separate locations, interacting via synchronous audio and visual computer channels. Our findings indicate an overall high level of perceived effectiveness and satisfaction with the instructional mode. In addition, significant relationships were established between facilitator effectiveness and student satisfaction, student motivation and class participation, student exam grades and perceived amount of group discussion. Findings indicate innovations in computer-mediated instructional designs can achieve desired levels of participant interaction considered critical to effective distance education technology. [source]

Understanding the shapes of bacteria just got more complicated

MOLECULAR MICROBIOLOGY, Issue 1 2006
Terry J. Beveridge
Summary The paper by Briegel et al. in this issue of Molecular Microbiology uses advanced cryo-transmission electron microscopy (cryoTEM) techniques to reveal four separate locations of cytoplasmic filament bundles in Caulobacter crescentus. Intuitively, these filaments should be rather rigid protein structures and composed of previously identified shape-forming proteins, such as crescentin or MreB. Yet, deletion mutants lacking these proteins still possessed filaments and still possessed wild-type morphology. These results suggest that a complex combination of protein structures, including those of crescentin, MreB and these newly identified bundles, in combination with the cell envelope help maintain the complicated shape of C. crescentus. Other bacteria might have similar architectural proteins to assist in maintaining the cell contours during growth and division. [source]

Connections of functional areas in the mustached bat's auditory cortex with the auditory thalamus

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2007
James M. Pearson
Abstract The auditory thalamus is the major target of the inferior colliculus and connects in turn with the auditory cortex. In the mustached bat, biosonar information is represented according to frequency in the central nucleus of the inferior colliculus (ICc) but according to response type in the cortex. In addition, the cortex has multiple areas with neurons of similar response type compared to the single tonotopic representation in the ICc. To investigate whether these transformations occur at the level of the thalamus, we injected anatomical tracers into physiologically defined locations in the mustached bat's auditory cortex. Injections in areas used for target ranging labeled contiguous regions of the auditory thalamus rather than separate patches corresponding to regions that respond to the different harmonic frequencies used for ranging. Injections in the two largest ranging areas produced labeling in separate locations. These results indicate that the thalamus is organized according to response type rather than frequency and that multiple mappings of response types exist. Injections in areas used for target detection labeled thalamic regions that were largely separate from those that interconnect with ranging areas. However, injections in an area used for determining target velocity overlapped with the areas connected to ranging areas and areas involved in target detection. Thus, separation by functional type and multiplication of areas with similar response type occurs by the thalamic level, but connections with the cortex segregate the functional types more completely than occurs in the thalamus. J. Comp. Neurol. 500:401,418, 2007. © 2006 Wiley-Liss, Inc. [source]