Photonic crystal fibers guide light by corralling it within a periodic array of microscopic air holes that run along the entire fiber length Largely through their ability to overcome the limitations of conventional fiber optics—for example, by permitting low-loss guidance of light in a hollow core—these fibers are proving to have a multitude of important technological and scientific applications spanning many disciplines The result has been a renaissance of interest in optical fibers and their uses

https://science.sciencemag.org/content/sci/299/5605/358.full.pdf

Photonic crystal fibers

The Cationminus signpi Interaction.

http://www.back-in-business-physiotherapy.com/images/files/DescendingControl.pdf

Descending control of pain.

The classical studies of nicotine by Langley at the turn of the 20th century introduced the concept of a “receptive substance,” from which the idea of a “receptor” came to light. Subsequent studies...

/pdf/mammalian-nicotinic-acetylcholine-receptors-from-structure-1woeprh7qg.pdf

Mammalian nicotinic acetylcholine receptors: from structure to function.

Presynaptic nicotinic ACh receptors.

Nicotinic acetylcholine receptors (nACh receptors2) in jawed vertebrates are prototypical members of the multisubunit, neurotransmitter-gated superfamily of ion channels (ionotropic neurotransmitter receptors; see Section IV for selected seminal papers, reviews, and collections). nACh receptors

https://pharmrev.aspetjournals.org/content/pharmrev/51/2/397.full.pdf

International Union of Pharmacology. XX. Current Status of the Nomenclature for Nicotinic Acetylcholine Receptors and Their Subunits

Kappa-bungarotoxin: a probe for the neuronal nicotinic receptor in the avian ciliary ganglion.

The functional role of nicotinic acetylcholine receptors (nAChRs) in the ventral lateral geniculate nucleus (LGNv) was examined in chick brain slices. Whole-cell patch-clamp recordings of neurons in the LGNv revealed the presence of bicuculline-resistant spontaneous postsynaptic currents (PSCs), which were subsequently blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), an AMPA receptor antagonist. Carbachol and other nicotinic agonists produced marked increases in the frequency of the glutamatergic spontaneous PSCs in the presence of tetrodotoxin, whereas they had little or no effect on current amplitude. The nicotinic receptor antagonist dihydro-beta-erythroidine (DHbetaE) blocked the carbachol-induced enhancement of spontaneous glutamatergic PSCs. alpha-bungarotoxin (alpha-BgTx) selectively blocked the nAChR-mediated enhancement of spontaneous glutamatergic PSCs but did not prevent nAChR-mediated enhancement of spontaneous GABAergic PSCs in the LGNv. Methyllycaconitine and strychnine, other blockers of nAChRs containing the alpha7 subunit, failed to inhibit carbachol's increase of spontaneous glutamatergic and GABAergic PSCs. These results demonstrate that the LGNv neurons receive both glutamatergic and GABAergic inputs and that the release of these transmitters can be modulated by different presynaptic nAChRs. Thus, the regulation of synaptic efficacy in the brain by presynaptic nAChRs can be complex, involving multiple neurotransmitters acting on the same neuron.

https://www.jneurosci.org/content/jneuro/18/6/1963.full.pdf

Glutamate and GABA Release Are Enhanced by Different Subtypes of Presynaptic Nicotinic Receptors in the Lateral Geniculate Nucleus

Molecular genetic and pharmacological studies have suggested that several subtypes of nicotinic acetylcholine receptors exist in the mammalian and avian brain. Combining 3H-(-)-nicotine, 125I-alpha-bungarotoxin, and 125I-kappa-bungarotoxin as ligands, we report here the first evidence for the existence in human frontal cortex of at least three different subtypes of nicotinic receptors. Autoradiographic analysis shows that specific 125I-kappa-bungarotoxin binding sites are concentrated mainly in several cortical layers. We also show that kappa-bungarotoxin, but not alpha-bungarotoxin decreases the evoked release of 3H-acetylcholine in rat cortical slices, indicating a likely presynaptic localization for some of the alpha-bungarotoxin-insensitive kappa-bungarotoxin sites in mammalian brain. The brains of patients with Alzheimer's disease show marked decreases in Bmax values for low-affinity 125I-kappa-bungarotoxin sites and both high- and low-affinity 3H-nicotine sites, whereas 125I-alpha-bungarotoxin sites are not significantly different in number from age-matched control brains. We conclude that Alzheimer's disease does not affect all subtypes of nicotinic receptors in the frontal cortex to the same extent.

Vincent A. Chiappinelli

Papers

International Union of Pharmacology. XX. Current Status of the Nomenclature for Nicotinic Acetylcholine Receptors and Their Subunits

Kappa-bungarotoxin: a probe for the neuronal nicotinic receptor in the avian ciliary ganglion.

Glutamate and GABA Release Are Enhanced by Different Subtypes of Presynaptic Nicotinic Receptors in the Lateral Geniculate Nucleus

Nicotinic acetylcholine receptor subtypes in human frontal cortex: changes in Alzheimer's disease.

Actions of snake venom toxins on neuronal nicotinic receptors and other neuronal receptors.