The sensory and motor connections of the cervical vagus nerves and of its inferior ganglion (nodose ganglion) have been traced in the medulla and upper cervical spinal cord of 16 male Wistar rats by using horseradish peroxidase (HRP) neurohistochemistry. The use of tetramethyl benzidine (TMB) as the substrate for HRP permitted the visualization of transganglionic and retrograde transport in sensory nerve terminals and perikarya, respectively. The vagus nerve in the rat enters the medulla in numerous fascicles with points of entry covering the entire lateral aspect of the medulla extending from level +4 to -6 mm rostrocaudal to the obex. Fascicles of vagal sensory fibers enter the dorsolateral aspect of the medulla and travel to the tractus solitarius (TS) which was labeled for over 8.8 mm in the medulla. The caudal extent of the TS receiving vagal projections was found in lamina V of the cervical spinal cord (C1 to C2). Sensory terminal fields could be visualized bilaterally in the nucleus of the tractus solitarius (nTS), area postrema (ap) and dorsal motor nucleus of the vagus nerve (dmnX). The ipsilateral projection to the nTS and the dmnX was heavier than that found on the contralateral side. The area postrema was intensely labeled on both sides. Motor fibers from HRP-labeled perikarya in the dmnX travel ventromedially in a distinct fascicle and subsequently subdivide into a number of small fiber bundles that traverse the medullary reticular formation in the form of a fine network of HRP-labeled fibers. As these fibers from the dmnX approach the ventrolateral aspect of the medulla they are joined by axons from the nucleus ambiguus (nA), nucleus retroambigualis (nRA) and the retrofacial nucleus (nRF). These latter fibers form hairpin loops in the middle of the reticular formation to accompany the axons from the dmnX exiting from the medulla in a ventrolateral location. HRP-labeled perikarya, in contrast to transganglionically transported HRP in sensory terminals in the nTS, were visualized on one side only, thus indicating that motor control via the vagus nerve is exerted only by motor neurons located ipsilaterally. Sensory information on the other hand, diverges to many nuclear subgroups located on both sides of the medulla.
Ionotropic glutamate receptors are composed of homomeric or heteromeric configurations of glutamate receptor subunits. We have cloned a member of a novel class of the rat ionotropic glutamate receptor family, termed chi-1. This subunit exhibits an average identity of 27% to NMDA subunits and 23% to non-NMDA subunits. Regional transcript levels of chi-1 are elevated just prior to and during the first postnatal week, with the highest levels present in the spinal cord, brainstem, hypothalamus, thalamus, CA1 field of the hippocampus, and amygdala. The spatial distribution of chi-1 expression is similar from postnatal day 1 (P1) to adulthood. However, transcript levels decline sharply between P7 and P14 and remain attenuated into adulthood. Functional expression studies in Xenopus oocytes injected with in vitro transcribed chi-1 RNA did not demonstrate agonist-activated currents. Pairwise expression of chi-1 with members of the AMPA, KA, or delta class of glutamate recepto subunits either failed to generate agonist-activated currents or failed to alter the underlying current generated by the coexpressed subunit. However, coexpression of chi-1 with subunits forming otherwise functional NMDA receptors resulted in an inhibition of current responses. Since chi-1 did not alter the currents generated by non-NMDA subunits, this suggests that chi-1 may specifically interact with NMDA receptor subunits. Further characterization will be required to establish the precise role of this glutamate receptor subunit in neuronal signaling.
We construct the entire three-parameter family of embedded constant mean curvature surfaces with three ends and genus zero. They are classified by triples of points on the sphere whose distances are the necksizes of the three ends. Because our surfaces are transcendental, and are not described by any ordinary di¤erential equation, it is remarkable to obtain such an explicit determination of their moduli space.
Methylobacterium is one of the most prevalent bacterial genera of the phyllosphere, present on the leaves of nearly every plant. Despite its ubiquity and its importance for host plant function, little is known about whether diversity over space and time within the genus reflects neutral processes like migration and drift, or environmental filtering of life history strategies and adaptations to temperature and host tree species. Here, we investigated how phylogenetic diversity within the genus Methylobacterium is structured by biogeography, seasonality, and growth strategies. Using deep, culture-independent barcoded marker gene sequencing coupled with culture-based approaches, we quantified seasonal shifts in Methylobacterium diversity over a year from early summer to fall in two temperate forests in Quebec, Canada. As an alternative to the 16S rRNA gene, we used rpoB, a highly polymorphic marker gene, which has not experienced detectable horizontal gene transfer nor copy number variation in Methylobacterium genomes. We cultured very different subsets of Methylobacterium diversity from the same leaf, depending upon the temperature of isolation and growth (20 C or 30 C). For instance, one the most abundant Methylobacterium lineages was almost exclusively isolated at 20 C, suggesting long-term adaptation to temperature. Both culture and barcoding approaches revealed that a considerable and previously underestimated diversity of Methylobacterium colonize the surface of leaves in temperate forests. This diversity was strongly structured according to both large (>100km; between forests) and small geographical scales (<1.2km within forests), and among host tree species, and was dynamic over seasonal time scales. To determine if these seasonal effects were driven by temperature, we measured growth of 79 isolates at different temperature treatments. Different lineages showed subtle and significant differences in growth performance when subject to temperature increase or decrease, but most have higher yield and slower growth rate at 20 than 30C, with strong lineage- and season-dependant variation in their overall growth strategies. We proposed that the homogenization of Methylobacterium community structure observed over a growing season resulted from the progressive replacement of isolates with high yield strategy typical of cooperative, structured communities, by isolates with rapid growth. Together our results show how Methylobacterium is phylogenetically structured into lineages with distinct growth strategies, which helps explain their differential abundance across regions, host tree species, and time. This works paves the way for further investigation of adaptive strategies and traits within a ubiquitous phyllosphere genus.
A substantial percentage of individuals who are chemically dependent also suffer from posttraumatic stress disorder and other survivor syndromes related to childhood abuse. The synergism of these multiple conditions creates unique treatment challenges. An enhanced, integrated treatment approach increases the chances of a successful clinical outcome. This article discusses a treatment model for chemical dependence and trauma-related syndromes that blends mental health and 12-Step and other chemical dependence treatment notions into an integrated approach that treats both disorders simultaneously and comprehensively. The model uses the strategic principle of "safety first" to drive all interventions and has five stages to organize the selection and timing of treatment tactics: crisis, skills, education, integration, and maintenance. This article also presents specific therapeutic tactics for each stage and a composit case example blending the history and recovery process of a survivor to illustrate the model in action.
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