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Smith EL, Robinson FA, Stern BE, Young FE. Studies in the stability of vitamins A and D: The effect of light on vitamin A. Biochem J 2006; 33:207-12. [PMID: 16746900 PMCID: PMC1264359 DOI: 10.1042/bj0330207] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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77
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Smith EL, Pickels EG. Micelle Formation in Aqueous Solutions of Digitonin. Proc Natl Acad Sci U S A 2006; 26:272-7. [PMID: 16588353 PMCID: PMC1078170 DOI: 10.1073/pnas.26.4.272] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Sakai E, Bi H, Maruko I, Zhang B, Zheng J, Wensveen J, Harwerth RS, Smith EL, Chino YM. Cortical Effects of Brief Daily Periods of Unrestricted Vision During Early Monocular Form Deprivation. J Neurophysiol 2006; 95:2856-65. [PMID: 16452254 DOI: 10.1152/jn.01265.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Experiencing daily brief periods of unrestricted vision during early monocular form deprivation prevents or reduces the degree of resulting amblyopia. To gain insight into the neural basis for these “protective” effects, we analyzed the monocular and binocular response properties of individual neurons in the primary visual cortex (V1) of macaque monkeys that received intermittent unrestricted vision. Microelectrode-recording experiments revealed significant decreases in the proportion of units that were dominated by the treated eyes, and the magnitude of this ocular dominance imbalance was correlated with the degree of amblyopia. The sensitivity of V1 neurons to interocular spatial phase disparity was significantly reduced in all treated monkeys compared with normal adults. With unrestricted vision, however, there was a small but significant increase in overall disparity sensitivity. Binocular suppression was prevalent in monkeys with constant form deprivation but significantly reduced by the daily periods of unrestricted vision. If neurons exhibited consistent responses to stimulation of the treated eye, monocular response properties obtained by stimulation of the two eyes were similar. These results suggest that the observed protective effects of brief periods of unrestricted vision are closely associated with the ability of V1 neurons to maintain their functional connections from the deprived eye and that interocular suppression in V1 may play an important role in regulating synaptic plasticity of these monkeys.
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Cockwell AE, Maloney VK, Thomas NS, Smith EL, Gonda P, Bass P, Crolla JA. Molecular investigation of a dicentric 13;17 chromosome found in a 21-week gestation fetus with multiple congenital abnormalities. Cytogenet Genome Res 2005; 112:166-9. [PMID: 16276107 DOI: 10.1159/000087530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Accepted: 02/21/2005] [Indexed: 11/19/2022] Open
Abstract
We report a 21-week gestation fetus terminated because of multiple congenital abnormalities seen on ultrasound scan, including ventriculomegaly, possible clefting of the hard palate, cervical hemivertebrae, micrognathia, abnormal heart, horseshoe kidney and a 2-vessel umbilical cord. On cytogenetic examination, the fetus was found to have a male karyotype with 45 chromosomes with a dicentric chromosome, which appeared to consist of the long arms of chromosomes 13 and 17. Molecular genetic investigations and fluorescence in situ hybridization (FISH) unexpectedly showed that the derivative chromosome contained two interstitial blocks of chromosome 17 short arm sequences, totalling approximately 7 Mb, between the two centromeres. This effectively made the fetus monosomic for approximately 15 Mb of 17p without the concurrent trisomy for another chromosome normally seen following malsegregation of reciprocal translocations. It also illustrates the complexity involved in the formation of some structurally abnormal chromosomes, which can only be resolved by detailed molecular investigations.
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Clark WD, Smith EL, Linn KA, Paul-Murphy JR, Muir P, Cook ME. Osteocyte apoptosis and osteoclast presence in chicken radii 0-4 days following osteotomy. Calcif Tissue Int 2005; 77:327-36. [PMID: 16307392 DOI: 10.1007/s00223-005-0074-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 06/22/2005] [Indexed: 11/30/2022]
Abstract
Osteocyte apoptosis caused by load-induced microdamage is followed by osteoclastic bone remodeling, and a causal link between apoptosis and repair has been suggested. The objectives of the present study were to use a chick model to examine the incidence of osteocyte apoptosis and the presence of osteoclasts during the first 96 hours following an osteotomy, prior to extensive callus mineralization. Osteotomies were performed on the right radii of 24 chicks at 23-24 days of age. The left radii served as controls. Radii were collected and processed at six time points following surgery (0, 12, 24, 48, 72, and 96 hours). Decalcified bone tissue sections were stained either for apoptosis using a modified TUNEL procedure or for tartrate-resistant acid phosphatase to identify osteoclasts in the intracortical and periosteal envelopes. The percentage of apoptotic osteocytes, as well as osteoclast counts (n/mm or n/mm2) were quantified in four regions (0-1, 1-2, 2-4, and 4-8 mm from the site of the osteotomy; regions 1-4, respectively) in the osteotomized radii and in the same measured areas in the control radii. Data for osteocyte apoptosis and osteoclasts in the control limb were subtracted from the osteotomized limb data to identify differences due to surgical influence. The incidence of osteocyte apoptosis was significantly higher at 12, 24, 48, and 72 hours versus 0 hours following osteotomy, and the response was highest in region 1; however, there was no interaction between time and region. Intracortical osteoclast counts (n/mm2) were elevated after 48 hours, and the response was similar in all regions. The data demonstrate that osteocyte apoptosis occurs within 24 hours in response to an osteotomy and temporally precedes an increase in osteoclast presence. Hence, osteocyte apoptosis may play a role in signaling during the bone healing process.
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Smith EL, Evans JE, Párraga CA. Myoclonus induced by cathode ray tube screens and low-frequency lighting in the European starling (Sturnus vulgaris
). Vet Rec 2005; 157:148-50. [PMID: 16055664 DOI: 10.1136/vr.157.5.148] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Scarlett A, Galloway TS, Canty M, Smith EL, Nilsson J, Rowland SJ. Comparative toxicity of two oil dispersants, superdispersant-25 and corexit 9527, to a range of coastal species. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2005; 24:1219-27. [PMID: 16111003 DOI: 10.1897/04-334r.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The acute toxicity of the oil dispersant Corexit 9527 reported in the literature is highly variable. No peer-reviewed data exist for Superdispersant-25 (SD-25). This study compares the toxicity of the two dispersants to a range of marine species representing different phyla occupying a wide range of niches: The marine sediment-dwelling amphipod Corophium volutator (Pallas), the common mussel Mytilus edulis (L.), the symbiotic snakelocks anemone Anemonia viridis (Forskål), and the seagrass Zostera marina (L.). Organisms were exposed to static dispersant concentrations for 48-h and median lethal concentration (LC50), median effect concentration (EC50), and lowest-observable-effect concentration (LOEC) values obtained. The sublethal effects of 48-h exposures and the ability of species to recover for up to 72 h after exposure were quantified relative to the 48-h endpoints. Results indicated that the anemone lethality test was the most sensitive with LOECs of 20 ppm followed by mussel feeding rate, seagrass photosynthetic index and amphipod lethality, with mussel lethality being the least sensitive with LOECs of 250 ppm for both dispersants. The results were consistent with current theory that dispersants act physically and irreversibly on the respiratory organs and reversibly, depending on exposure time, on the nervous system. Superdispersant-25 was found overall to be less toxic than Corexit 9527 and its sublethal effects more likely to be reversible following short-term exposure.
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Cooper JM, Cubitt R, Dalgliesh RM, Gadegaard N, Glidle A, Hillman AR, Mortimer RJ, Ryder KS, Smith EL. Dynamic in Situ Electrochemical Neutron Reflectivity Measurements. J Am Chem Soc 2004; 126:15362-3. [PMID: 15563146 DOI: 10.1021/ja044682s] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the first dynamic in situ electrochemical neutron reflectivity (NR) measurements on electroactive films. By using a boxcar integration strategy within a cyclic voltammetric experiment, it is possible to acquire neutron reflectivity data associated with narrow, defined windows of potential. Accumulation of data from repetitive cycles allows one to build up potential- (time-) resolved profiles. The effective time resolution is now on the order of seconds, as compared to ca. 1 h using conventional methodology, making in situ NR a practical technique for dynamic electrochemical studies. Illustrative data for polyvinylferrocene films reveal hysteresis in (de)swelling, incomplete desolvation upon reduction, and transient salt retention, all of which respond to time-scale variations.
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Greenwood VJ, Smith EL, Goldsmith AR, Cuthill IC, Crisp LH, Walter-Swan MB, Bennett AT. Does the flicker frequency of fluorescent lighting affect the welfare of captive European starlings? Appl Anim Behav Sci 2004. [DOI: 10.1016/j.applanim.2003.11.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Crowe TP, Smith EL, Donkin P, Barnaby DL, Rowland SJ. Measurements of sublethal effects on individual organisms indicate community-level impacts of pollution. J Appl Ecol 2004. [DOI: 10.1111/j.1365-2664.2004.00882.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Donkin P, Smith EL, Rowland SJ. Toxic effects of unresolved complex mixtures of aromatic hydrocarbons accumulated by mussels, Mytilus edulis, from contaminated field sites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2003; 37:4825-4830. [PMID: 14620806 DOI: 10.1021/es021053e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Exposure of marine mussels (Mytilus edulis) to an unresolved complex mixture (UCM) of aromatic hydrocarbons isolated from a crude oil has been shown to reduce their feeding rate by 40%. The present study was undertaken to determine whether UCMs bioaccumulated by mussels in the field are also toxic. The feeding rate of mussels derived from polluted sites increased when they were placed in clean water, pointing to a loss of toxic agents from the tissues. At the end of the depuration period, water in which mussels from an oil-polluted site had been held contained a UCM. Steam-distillation extracts of the tissues of mussels taken from several polluted sites were shown to be highly toxic to the feeding activity of juvenile mussels. The tissues of mussels from these sites contained UCMs. Nontoxic steam distillates from clean mussels did not. Steam-distillation extracts of mussels from an oil-polluted site were fractionated by normal-phase high-performance liquid chromatography. A fraction, largely comprising a "monoaromatic" UCM, reduced the feeding rate of juvenile mussels by 70%. Two later-eluting fractions containing aromatic UCMs also produced smaller depressions in feeding rate. These results support our contention that some aromatic UCM hydrocarbons constitute a forgotten pollutant burden in the marine environment.
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Greenwood VJ, Smith EL, Church SC, Partridge JC. Behavioural investigation of polarisation sensitivity in the Japanese quail (Coturnix coturnix japonica) and the European starling (Sturnus vulgaris). J Exp Biol 2003; 206:3201-10. [PMID: 12909701 DOI: 10.1242/jeb.00537] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many animals have sensitivity to the e-vector of linearly polarised light, which may assist in visually mediated behaviours such as navigation, signalling and foraging. However, it is still controversial as to whether birds possess polarisation sensitivity. Several studies have found that altering the polarisation patterns of the broad visual field surrounding birds alters their intended migratory orientation. However, electrophysiological tests have failed to elicit evidence for polarisation sensitivity in birds, and the mechanism by which birds might perceive polarised light is unknown. In this experiment, we trained Japanese quail and European starlings to discriminate stimuli differing in their polarisation pattern. Although both quail and starlings were able to discriminate stimuli in which the stimulus sub-components either differed or had the same radiant intensity (the control task), they were unable to discriminate stimuli in which the e-vector orientations of the stimulus sub-components either differed by 90 degrees or had the same angle of polarisation. The birds' successful performance on the control task, but failure to complete the polarisation task, demonstrated that they had all the necessary cognitive abilities to make the discrimination except sensitivity to angle of polarisation. We conclude that quail and starlings are unable to use polarisation cues in this foraging task.
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Jones DB, Broeckmann E, Pohl T, Smith EL. Development of a mechanical testing and loading system for trabecular bone studies for long term culture. Eur Cell Mater 2003; 5:48-59; discussion 59-60. [PMID: 14562272 DOI: 10.22203/ecm.v005a05] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A highly accurate (+/-3%) mechanical loading and measurement system combined with a trabecular bone diffusion culture-loading chamber has been developed, which provides the ability to study trabecular bone (and possibly) cartilage under controlled culture and loading conditions over long periods of time. The loading device has been designed to work in two main modes, either to apply a specific compressive strain to a trabecular bone cylinder or to apply a specific force and measure the resulting deformation. Presently, precisely machined bone cylinders can be loaded at frequencies between 0.1 Hz to 50 Hz and amplitudes over 7,000 microepsilon. The system allows accurate measurement of many mechanical properties of the tissue in real time, including visco-elastic properties. This paper describes the technical components, reproducibility, precision, and the calibration procedures of the loading system. Data on long term culture and mechanical responses to different loading patterns will be published separately.
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Greenwood VJ, Smith EL, Cuthill IC, Bennett AT, Goldsmith AR, Griffiths R. Do European starlings prefer light environments containing UV? Anim Behav 2002. [DOI: 10.1006/anbe.2002.1977] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Smith EL, Greenwood VJ, Bennett ATD. Ultraviolet colour perception in European starlings and Japanese quail. J Exp Biol 2002; 205:3299-306. [PMID: 12324539 DOI: 10.1242/jeb.205.21.3299] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYWhereas humans have three types of cone photoreceptor, birds have four types of single cones and, unlike humans, are sensitive to ultraviolet light(UV, 320-400 nm). Most birds are thought to have either a violet-sensitive single cone that has some sensitivity to UV wavelengths (for example, many non-passerine species) or a single cone that has maximum sensitivity to UV(for example, oscine passerine species). UV sensitivity is possible because,unlike humans, avian ocular media do not absorb UV light before it reaches the retina. The different single cone types and their sensitivity to UV light give birds the potential to discriminate reflectance spectra that look identical to humans. It is clear that birds use UV signals for a number of visual tasks,but there are few studies that directly demonstrate a role for UV in the detection of chromaticity differences (i.e. colour vision) as opposed to achromatic brightness. If the output of the violet/UV cone is used in achromatic visual tasks, objects reflecting more UV will appear brighter to the bird. If, however, the output is used in a chromatic mechanism, birds will be able to discriminate spectral stimuli according to the amount of reflected light in the UV part of the spectrum relative to longer wavelengths. We have developed a UV `colour blindness' test, which we have given to a passerine(European starling) and a non-passerine (Japanese quail) species. Both species learnt to discriminate between a longwave control of orange vs red stimuli and UV vs `non-UV' stimuli, which were designed to be impossible to differentiate by achromatic mechanisms. We therefore conclude that the output of the violet/UV cone is involved in a chromatic colour vision system in these two species.
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Smith EL. Highlights from the annual scientific assembly: weapons of mass destruction: organized medicine's role in the national response to terrorism. South Med J 2001; 94:1223-9. [PMID: 11811866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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Akman HO, Zhang H, Siddiqui MA, Solomon W, Smith EL, Batuman OA. Response to hypoxia involves transforming growth factor-beta2 and Smad proteins in human endothelial cells. Blood 2001; 98:3324-31. [PMID: 11719370 DOI: 10.1182/blood.v98.12.3324] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Oxygen deprivation (hypoxia) is a consistent component of ischemia that induces an inflammatory and prothrombotic response in the endothelium. In this report, it is demonstrated that exposure of endothelial cells to hypoxia (1% O(2)) increases messenger RNA and protein levels of transforming growth factor-beta2 (TGF-beta2), a cytokine with potent regulatory effects on vascular inflammatory responses. Messenger RNA levels of the TGF-beta2 type II membrane receptor, which is a serine threonine kinase, also increased. The stimulatory effect of hypoxia was found to occur at the level of transcription of the TGF-beta2 gene and involves Smad proteins, a class of intracellular signaling proteins that mediates the downstream effects of TGF-beta receptors. Transient transfection studies showed that the region spanning -77 and -40 base pairs within the TGF-beta2 promoter (harboring a Smad-binding "CAGA box") is activated in hypoxic cells compared with nonhypoxic controls (P <.01). Hypoxia also stimulated transcription from another promoter, 3TP-Lux, a reporter construct responsive to Smads and TGF-beta. In addition, specific binding to a Smad-binding oligonucleotide was observed with nuclear extracts from hypoxic endothelial cells but not from nonhypoxic cells. It is concluded that Smad proteins, which can regulate endothelial responses to mechanical and inflammatory stress, also may play an important role in vascular responses to hypoxia and ischemia.
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Smith EL. Abraham White: March 8, 1908-February 14, 1980. BIOGRAPHICAL MEMOIRS. NATIONAL ACADEMY OF SCIENCES (U.S.) 2001; 55:507-36. [PMID: 11616088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Smith EL, Hill RL. Philip Handler: August 13, 1917 - December 29, 1981. BIOGRAPHICAL MEMOIRS. NATIONAL ACADEMY OF SCIENCES (U.S.) 2001; 55:305-53. [PMID: 11616084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Coplan JD, Smith EL, Altemus M, Scharf BA, Owens MJ, Nemeroff CB, Gorman JM, Rosenblum LA. Variable foraging demand rearing: sustained elevations in cisternal cerebrospinal fluid corticotropin-releasing factor concentrations in adult primates. Biol Psychiatry 2001; 50:200-4. [PMID: 11513819 DOI: 10.1016/s0006-3223(01)01175-1] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND The authors previously reported elevated cerebrospinal fluid (CSF) corticotropin-releasing factor (CRF) concentrations in juvenile primates nursed by mothers undergoing experimentally imposed unpredictable foraging conditions in comparison to normally reared controls. The purpose of the present study was to determine if these changes would endure into young adulthood. METHODS Cisternal CSF samples were obtained from those unpredictably reared young adult primates who had been previously studied as juveniles and age-matched ad libitum normally reared controls. Samples were assayed for CSF CRF. RESULTS Concentrations of CSF CRF were significantly elevated in the unpredictably reared sample in comparison to the ad libitum-reared control group. A significant positive correlation was noted between juvenile and young adult CSF CRF values within the unpredictably reared cohort. CONCLUSIONS Disturbances of maternal-infant attachment processes have an enduring impact on primate CRF function into young adulthood. The CRF elevations following unpredictable maternal foraging conditions appear traitlike in nature.
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Mathew SJ, Coplan JD, Schoepp DD, Smith EL, Rosenblum LA, Gorman JM. Glutamate-hypothalamic-pituitary-adrenal axis interactions: implications for mood and anxiety disorders. CNS Spectr 2001; 6:555-6, 561-4. [PMID: 15573019 DOI: 10.1017/s1092852900002091] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is a pathologic feature of certain mood and anxiety disorders that results in the increased production and secretion of corticotropin-releasing factor. There is increasing preclinical evidence that glutamate, an excitatory amino acid, plays an important role in the regulation of the HPA axis. Activation of glutamatergic projections to limbic structures such as the amygdala and brainstem structures such as the nucleus tractus solitarius is implicated in the stress response. There are laboratory and clinical suggestions that glutamatergic N-methyl-D-aspartate (NMDA) receptor antagonists function as antidepressants, and that chronic antidepressant treatments have a significant impact on NMDA receptor function. Clinical investigations of glutamate antagonists in patients with mood and anxiety disorders are in their infancy, with a few reports suggesting the presence of mood-elevating properties. Ultimately, HPA axis modulators, serotonin-enhancing agents, and glutamate antagonists might serve to increase neurotropic factors in key brain regions for affective and anxiety regulation, providing a putative final common pathway.
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Coplan JD, Mathew SJ, Smith EL, Trost RC, Scharf BA, Martinez J, Gorman JM, Monn JA, Schoepp DD, Rosenblum LA. Effects of LY354740, a novel glutamatergic metabotropic agonist, on nonhuman primate hypothalamic-pituitary-adrenal axis and noradrenergic function. CNS Spectr 2001; 6:607-12, 617. [PMID: 15573025 DOI: 10.1017/s1092852900002157] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The search for novel anxiolytics and antidepressants has focused on compounds with the potential to reduce excessive hypothalamic-pituitary-adrenal (HPA) axis activity. L-glutamate, an excitatory neurotransmitter ubiquitously present within the central nervous system, conceivably plays an important role in activating the neural sites involved in stress modulation. Deactivation of the HPA axis by glutamatergic neurotransmission modulation may represent a novel therapeutic approach. Accordingly, the acute intravenous effects of the novel metabotropic (mGlu2/3) agonist LY354740 were tested on bonnet macaques (Macaca radiata) undergoing acute infusions of yohimbine, a noradrenergic stimulant. Dependent measures were the magnitude of the increase of plasma cortisol and plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) customarily elicited by yohimbine. Next, the effects of 6 weeks of chronic oral administration of LY354740 on baseline (postcapture) plasma cortisol and MHPG levels in comparison to the identical measure in untreated controls were assessed. Subjects chronically treated with LY354740 received yohimbine infusions which were compared to yohimbine infusions and saline infusions in non-LY354740-treated subjects. Preliminary evidence supports the view that acute LY354740 infusion resulted in a marked diminution of yohimbine-induced stress response, as manifest by a substantial attenuation of cortisol and MHPG response observed in comparison to the saline-treated yohimbine condition. Chronic oral administration of LY354740 led to postcapture baseline cortisol levels which were markedly reduced (approximately 50 percent) in comparison to untreated control subjects; however, there were no significant parallel differences in MHPG levels. Yohimbine infusions elicited an increase in cortisol and MHPG levels in both LY354740-treated and non-LY354740-treated subjects, in comparison to declines in cortisol values observed following vehicle infusions (group X time interaction; P<.0001). Chronic LY354740-treated subjects failed to achieve cortisol levels comparable in range to those of untreated subjects primarily because of their low baseline cortisol levels. In contrast, despite equivalent baselines, yohimbine-induced MHPG values were increased overall in the chronically treated group compared to the saline and yohimbine-alone groups. Thus, LY354740 markedly reduced the acute corticoid and noradrenergic response elicited by yohimbine infusion. Chronic administration of LY354740 appears to present a safe and effective mechanism to markedly down-modulate the HPA axis while retaining noradrenergic responsivity.
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Chino Y, Smith EL, Zhang B, Matsuura K, Mori T, Kaas JH. Recovery of binocular responses by cortical neurons after early monocular lesions. Nat Neurosci 2001; 4:689-90. [PMID: 11426222 DOI: 10.1038/89469] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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