PubMed Health⌕ Search

Biomedical subjects

G M Shambes

Publications and source records attributed to G M Shambes.

7 recordsLinked to original sources
PubMed1992

Biomechanical analysis of the sit-to-stand motion in elderly persons.

The sit-to-stand motion of ten healthy subjects, 65 to 76 years old, was evaluated using kinematic, force plate, and electromyographic data to characterize the sit-to-stand motion. Kinematic data collected by video, muscle activity monitored by surface electromyography, and ground reaction forces analyzed by a piezoelectric force plate were used for analysis. Using these synchronized data, three phases of the sit-to-stand motion were identified--phase 1, weight shift; phase 2, transition; and phase 3, lift. A consistent pattern of trunk and lower extremity motion was observed, and two distinct upper extremity movement strategies were identified. The onset of muscle activity occurred in the following order: erector spinae, rectus femoris, and vastus medialis (phase 1); biceps femoris, gluteus maximus, and rectus abdominus (phase 2). This characterization of the sit-to-stand motion for a small population of healthy elderly subjects serves as a basis for identifying problems in elderly patients who demonstrate difficulty getting up from a chair.

Adult↗
PubMed1988

Somatosensory projections of cerebellar granule cell layer of giant bushbaby, Galago crassicaudatus.

Recent neurophysiological studies of the granule cell (GC) layer in opossums and rats revealed extensive somatosensory projections to the cerebellar hemispheres and caudal vermis. These projections are organized as asomatotopic mosaics that are species-specific. To determine whether similar projections exist in a primate with a relatively small and simple cerebellum, we explored the GC layer of exposed folial crowns of anterior and posterior lobe cerebellar cortex of anesthetized giant galagos using juxtathreshold natural stimulation of mechanoreceptors and in-depth microelectrode micromapping techniques. We found (1) that stimulation of somatosensory mechanoreceptors by gentle touch, deep pressure, muscle stretch and joint movement revealed projections to the GC layer throughout the mediolateral extent of crus II, paramedian lobule, pyramis and rostral uvula (crus I was unresponsive); (2) that mosaic patterns of peripheral sources and submodality of projections were different for each lobule, and (3) that there were intraspecies and individual differences in subfoliation and in details of projections. Except for differences in mosaic pattern and relative size of different projections, these findings are similar to those in opossums and rats. These data suggest that somatosensory inputs to the cerebellum are not only functionally significant, but that they exist widely among mammals.

Animals↗
PubMed1978

Tactile projections to granule cells in caudal vermis of the rat's cerebellum.

We discovered a small tactile area in a single a folium of the uvula of the cauday vermis of the rat's cerebellum. Gentle mechanical stimulation of relatively small cutaneous receptive fields (RFs) activated multiple units in the granule cell (GC) layer in a portion of a single folium in rats anesthetized with sodium pentobarbital. The total size of this area on each side of the midline is about 1.5 mm2, yet micromapping within this tiny region using tungsten ball microelectrodes and a high puncture sampling density (about 75 punctures/mm2) revealed a highly differentiated pattern of cutaneous projections to the GC layer. All peripheral projections are ipsilateral; the two homologous areas from each side adjoining at the midline of folium 9a. The larger projection areas from cutaneous RFs are mostly from mystacial vibrissae and upper lip, but small projection sites from the remainder of the head, neck and forelimb also are present. The pattern of projections were patch-like, forming a fractured somatotopic pattern or mosaic, with some somatotopic and some nonsomatotopic features. Each RF activated units in a vertical column in the GC layer. This area has not been described in any mammal, and its functional role can now be studied.

Afferent Pathways↗
PubMed1976

Static postural control in children.

The purpose of this study was to investigate "static" balance characteristics in four and eight year old children performing six developmental tasks leading to upright stance. The data were evaluated with electromyographic, center of gravity and photographic procedures. The results of the study indicated that the older age group of children demonstrated higher degrees of motor control in all the balance tasks involving upper and/or lower extremity support of the trunk. The eight year old children showed less postural sway, more definitive muscular localizations and smaller degrees of motor activity occurring during the execution of the developmental tasks.

Age Factors↗
PubMed1975

Aging and postural sway in women.

The effects of aging on postural sway in upright and forward lean stance were investigated. Postural sway was measured on a center of gravity apparatus using two age groups of female subjects 20 to 30 years old and 70 to 80 years old. The older adults demonstrated significantly larger sway areas than the young adults in both stance positions. The patterning of the center of gravity projections on the base of support tended to be similar under all conditions except in the young adults/upright position where the antero-postero excursion was larger than the medial-lateral. The mean locations of the center of gravity projections were often posterior and to the left of the geometric center of the base of support. The distance between the two points was least in the older adults/forward lean position, i.e., the experimental unit which demonstrated the largest area of sway.

Adult↗