Differential innervation of protruder and retractor muscles of the tongue in rat

Protrusion and retraction of the tongue are essential components of such orofacial behaviors as mastication, respiration, and swallowing. Stimulation of the medial branch of the hypoglossal nerve yields tongue protrusion, while stimulation of the lateral branch yields tongue retraction in rat. We exploited the transsynaptic transport capabilities of pseudorabies virus to determine specific circuits that innervate protruder and retractor muscles of the rat tongue. Each group of muscles is innervated by distinct populations of hypoglossal motoneurons: caudal ventral and ventrolateral motoneurons form the largest proportion of those innervating protruders, whereas rostral dorsal motoneurons innervate retractors. Our primary finding was differential innervation of protruder and retractor motoneurons by premotoneurons in the lateral tegmental field: premotoneurons innervating protruder motoneurons were more ventral and ventromedial than those innervating retractor motoneurons. In addition, protruder motoneurons received projections from the ipsilateral lateral parabrachial nucleus but not spinal trigeminal nucleus or medial and ventral subnuclei of the solitary tract; the converse was true for retractor motoneurons. These results suggest segregation of functional networks that control hypoglossal motoneurons. The dorsal medulla, in or around the solitary tract, contains neurons specific to retractor motoneurons, and the region ventrolateral to the hypoglossal nucleus contains circuitry specific to protruder motoneurons. Common innervation of medial and lateral branch motoneurons is provided by premotoneurons in the raphe and gigantocellular reticular formation of the medial medulla. The midline medullary nuclei with diverse projections may coordinate complex behavior or modulate general motoneuron excitability, whereas the lateral reticular formation, with anatomically discrete projections, may control motoneurons that contribute to distinct orofacial behaviors. © 1995 Wiley-Liss, Inc.     

Urban epizootic of rabies in Mexico: epidemiology and impact of animal bite injuries.

From 1 July 1987 to 31 December 1988, a total of 317 animals (91% of which were dogs) were confirmed to have rabies in Hermosillo, Mexico. The median age of rabid dogs was 1 year, 69% were male, and 98% were owned. The epizootic started in the southern areas of the city, rapidly involved the entire city, and persisted mainly in lower socioeconomic status areas. The area of the city and mean household size were significant predictor variables for the population density of rabid dogs around household clusters (Poisson linear regression, P < 0.001 and P = 0.03, resp). Approximately 2.5% of city residents were bitten by dogs in 1987, with the rate of reported dog bite injuries being positively correlated with mean household size and the proportion of households that owned dogs. Visits to the city health centre for evaluation of possible exposures to rabies increased by 135% after the start of the epizootic; approximately 273 per 100,000 city residents were administered a full or partial course of rabies post-exposure prophylaxis in 1987. Children were at greatest risk for exposures to rabies, accounting for 60% of all reported animal bite injuries evaluated at the health centre. Also they were more likely than older persons to have received bite injuries to the head, face, and neck (odds ratio = 21.6, 95% confidence interval = 5.4, 186.5).     

Life expectancy in an aboriginal Malaysian population.

A life table for an aboriginal Malaysian population, the Semelai, living in West Malaysia, was constructed using censuses from 1965, 1969, and 1974; and interview data from 1974. The life expectancy at birth for this population, 54.0 years, was compared to that of other Malaysian populations and selected Asian populations. This comparison indicated that the Semelai were at a disadvantage compared to the Malaysian populations, but in a favorable position when compared with the other Asian populations.     

Skin Temperature Self-Regulation and Non-Invasive Regional Cerebral Blood Flow

SYNOPSIS
Theoretical notions concerning the mechanism of migraine alleviation via "hand-warming" techniques remain unclear and are somewhat hampered by a lack of knowledge as to what effect skin temperature self-regulation has on intracerebral blood flow. Twelve normal female subjects were trained either to increase or to decrease the skin temperature of their hands. Following extensive training, subjects were given one measure of non-invasive regional cerebral blood flow (rCBF) during a relaxation run and another measure while self-regulating their skin temperature. The skin temperatures of the hand-warming and hand-cooling groups changed in significantly opposite directions. However the rCBF of either the left or right hemispheres showed no such concomitant differentiation. The present study contributes physiological confirmation of existing clinical indications that skin temperature manipulation per se may not be the major factor responsible for the therapeutic gains seen in migraine therapy.