Indirect evidence suggests that excitatory amino acids (EAA) are involved in synaptic transmission of visceral afferents at their synapses within the nucleus tractus solitarius (NTS). Little is known about the identity of the postsynaptic receptors or response mechanisms. Here we report results from a longitudinal brain slice of the rat medulla. Intracellular recordings were made from neurons in delimited portions of the dorsal medial NTS (mNTS) known to receive baroreceptor inputs. Stimulation of the solitary tract 1-3 mm from the mNTS recording site evoked short (2 ms) latency excitatory postsynaptic potentials (EPSPs), which had durations of 40-50 ms. Addition of the non-N-methyl-D-aspartate (non-NMDA) selective antagonist 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX) to the slice surface near the recording electrode resulted in a rapid (within 30-45 s) suppression of the EPSP. Complete EPSP blockade was only slowly reversed by drug-free saline. Concentration-response relations (n = 14) showed 50% depression of EPSPs by surface concentrations of 1-10 microM CNQX. EPSP amplitude was resistant to the selective NMDA antagonist 2-amino-5-phosphonovalerate (AP 5) and, on average, was reduced less than 20% at 100 microM AP 5, an effect that was not statistically significant (n = 10; P greater than 0.05). In conclusion, this study offers the first direct evidence that EAAs mediate the primary events of afferent synaptic transmission in NTS. The experiments suggest that excitatory sensory afferent synaptic transmission to mNTS neurons is mediated by an EAA transmitter acting at non-NMDA receptors, but NMDA receptors may have a modulatory role.

No abstract

Based on these results, it is suggested that the rich geological and ecological diversity caused by the recent large-scale uplifts of the Qinghai-Tibetan Plateau since the late Tertiary, coupled with the oscillating climate of the Quaternary stage, might have promoted rapid speciation in small and isolated populations, as well as allowing the fixation of unique or rare morphological characters in Rheum. Such a rapid radiation, combined with introgressive hybridization and reticulate evolution, may have caused the transfer of cpDNA haplotypes between morphologically dissimilar species, and might account for the inconsistency between morphological classification and molecular phylogeny reported here.

The aesthetic surgeon may occasionally be consulted by a patient who wishes to discuss what can be done for the scars of self-inflicted wounds on the forearms. These scars are popularly referred to as "hesitation marks" or "suicide gestures." Unlike patients suffering from factitial ulcers or Münchhausen syndrome, these patients will admit to the physician that the scars are the result of self-inflicted wounds. These scars often consist of multiple, parallel, white lines extending up and down the forearms (usually volar surface), with more on the nondominant side. Although the pattern of these scars is apparently what drives these patients to the aesthetic surgeon for relief (because even lay people identify these scars as self-inflicted suicide marks), the authors propose a new and deeper motivation for surgery. Recent experiences with three of these patients resulted in an epiphany that prompted this report. Once the symbolic meaning of these scars was broached, a torrent of thoughts and theories followed. This article will recount these three cases and present a central thesis for this type of self-inflicted injury. A proposal for the proper surgical treatment of this condition will be offered. Uniquely, two of the patients will relate their own stories and propose guidelines and warnings for the aesthetic surgeon.