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Biomedical subjects

S Matteson

Publications and source records attributed to S Matteson.

13 recordsLinked to original sources
PubMed2006

Neural correlates of tic generation in Tourette syndrome: an event-related functional MRI study.

Little is known about the neural correlates of tics and associated urges. In the present study, we aimed to explore the neural basis of tics in patients with Tourette syndrome by using event-related functional MRI (fMRI). Ten patients (6 women, 4 men; age: mean +/- SD = 31 +/- 11.2) were studied while spontaneously exhibiting a variety of motor and vocal tics. On the basis of synchronized video/audio recordings, fMRI activities were analysed 2 s before and at tic onset irrespective of the clinical phenomenology. We identified a brain network of paralimbic areas such as anterior cingulate and insular cortex, supplementary motor area (SMA) and parietal operculum (PO) predominantly activated before tic onset (P < 0.05, corrected for multiple comparisons). In contrast, at the beginning of tic action, significant fMRI activities were found in sensorimotor areas including superior parietal lobule bilaterally and cerebellum. The results of this study indicate that paralimbic and sensory association areas are critically implicated in tic generation, similar to movements triggered internally by unpleasant sensations, as has been shown for pain or itching.

Adult↗
PubMed2001

Regulation of the growth of multinucleated muscle cells by an NFATC2-dependent pathway.

The nuclear factor of activated T cells (NFAT) family of transcription factors regulates the development and differentiation of several tissue types. Here, we examine the role of NFATC2 in skeletal muscle by analyzing adult NFATC2(-/)- mice. These mice exhibit reduced muscle size due to a decrease in myofiber cross-sectional area, suggesting that growth is blunted. Muscle growth was examined during regeneration after injury, wherein NFATC2-null myofibers form normally but display impaired growth. The growth defect is intrinsic to muscle cells, since the lack of NFATC2 in primary muscle cultures results in reduced cell size and myonuclear number in myotubes. Retroviral-mediated expression of NFATC2 in the mutant cells rescues this cellular phenotype. Myonuclear number is similarly decreased in NFATC2(-/)- mice. Taken together, these results implicate a novel role for NFATC2 in skeletal muscle growth. We demonstrate that during growth of multinucleated muscle cells, myoblasts initially fuse to form myotubes with a limited number of nuclei and that subsequent nuclear addition and increases in myotube size are controlled by a molecular pathway regulated by NFATC2.

Animals↗
PubMed2000

Hepatocyte growth factor affects satellite cell activation and differentiation in regenerating skeletal muscle.

Hepatocyte growth factor (HGF) is the only known growth factor that activates quiescent satellite cells in skeletal muscle. We hypothesized that local delivery of HGF may enhance regeneration after trauma by increasing the number of myoblasts available for restoring normal tissue architecture. Injection of HGF into muscle at the time of injury increases myoblast number but does not enhance tissue repair as determined using quantitative histological analyses. Rather, depending on the dose and the timing of HGF administration relative to the injury, regeneration can be inhibited. The greatest inhibitory effect is observed when HGF is administered on the day of injury and continued for 3 days, corresponding to the time when satellite cell activation, proliferation, and early differentiation normally occur. To establish a mechanism for this inhibition, we show that HGF can act directly on primary muscle cells to block differentiation. These results demonstrate that 1) exogenous HGF synergizes with factors in damaged muscle to increase myoblast number, 2) regeneration is not regulated solely by myoblast number, and 3) HGF inhibits muscle differentiation both in vitro and in vivo.

Animals↗
PubMed1996

Reduced top-down influence in auditory perceptual organization in schizophrenia.

Perceptual organization of auditory information is influenced by both the physical characteristics and the categorization of irrelevant information. This study sought to determine the degree to which schizophrenia patients could utilize acoustic properties and contextual cues (top-down factors) to segregate relevant from irrelevant material in an auditory stream. On a modification of I. Neath, A. M. Surprenant, and R. G. Crowder's (1993) auditory suffix task, both schizophrenia and control participants demonstrated better recall of relevant information when irrelevant information had different physical characteristics, compared with when both arose from the same source. In contrast, schizophrenia patients were unaffected by a contextual manipulation that allowed controls to reduce the interfering effect of an irrelevant stimulus. These data suggest that a reduced ability to utilize contextual information plays a role in the perceptual organization dysfunction in schizophrenia.

Adult↗
PubMed1995

Global trends in oral and maxillofacial radiology education.

Although the content of the undergraduate dental curriculum has evolved alongside the changes in dental practice, the methods and structure of the course have remained remarkably constant. In this article the recent developments in higher education are reviewed in depth and some changes in the pattern and setting of oral health outlined. Global trends in education in oral and maxillofacial radiology, with particular reference to undergraduate, postgraduate, and continuing professional education, are described against this background.

Chile↗
PubMed1992

Direct digital radiography for the detection of periodontal bone lesions.

In this study the diagnostic accuracy of D-speed and E-speed film in the detection of simulated periodontal bone lesions was compared with that of an electronic direct digital image receptor. Lesions of increasing depth were created in 11 human hemimandibles at the buccal cortical plate in the interproximal marginal bone area by means of 1.4 mm diameter round bursa. Specimens were imaged at each lesion stage with the use of all three receptors. Nine viewers used a 5-point rating scale to evaluate whether lesions were present or absent in the resulting images. Receiver operating characteristic curves were generated, and maximum-likelihood curve areas were calculated. The area under the curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for D-speed film, E-speed film, and the direct digital system were 0.745 +/- 0.038, 0.740 +/- 0.038, and 0.741 +/- 0.037, respectively. Critical ratio analysis was used to compare the means. No statistical difference was found between any of the three image receptors (p > 0.05) for the detection of simulated periodontal lesions 1.0 to 3.0 mm in depth, which suggested that the digital system performed comparably with conventional film systems.

Alveolar Bone Loss↗
PubMed1986

The relationship between the dentist's year of graduation and ordering of bitewing radiographs.

This article reports the results of a survey of general practice dentists on the relationship of the dentist's year of graduation to the ordering of bitewing radiographs for patients. More recent graduates were more likely to indicate ordering the radiographs at 6-month intervals. There were no differences in ordering associated with the dentist's experience. Shorter intervals between ordering were indicated by all dentists for patient groups at high risk of caries.

Adolescent↗
PubMed1984

Photocephalometry: errors of projection and landmark location.

A method called photocephalometry was recently described for the possible soft-tissue evaluation of orthognathic surgery patients by the superimposition of coordinated cephalographs and photographs. A grid analysis was performed to determine the accuracy of the superimposition method. In addition, the reliability of landmark identification was analyzed by the method error of Baumrind and Frantz, using three replicates of twelve patients' photographs. Comparison of twenty-one grid intervals showed that the magnification of the photographic image for any given grid plane is not correlated to that of the radiographic image. Accurate comparisons between soft- and hard-tissue anatomy by simply superimposing the images are not feasible because of the difference in the enlargement factors between the photographs and x-ray films. As was noted by Baumrind and Frantz, a wide range exists in the variability of estimating the location of landmarks. Sixty-six percent of the lateral photographic landmarks and 57% of the frontal landmarks had absolute mean errors for all twelve patients that were less than or equal to 2.0 mm. In general, the envelope of error for most landmarks was not circular. Although the photocephalometric apparatus as described by Hohl and colleagues does not yield the desired quantitative correlation between hard and soft tissues, valuable quantitative information on soft tissue can be easily obtained with the standardization and replication possible with the camera setup and enlarged photographs.

Adult↗
PubMed1983

A simple method for taking natural-head-position cephalograms.

Standing natural head position is a reproducible, physiologically determined aspect of function. Recent studies have demonstrated associations between this aspect of function and the form of the skeletodental features, in both growing and nongrowing persons. A simple method has been devised which obviates the need for multiple radiographs to determine the clinical reliability of the method. The device, its construction, and method of use are described.

Cephalometry↗