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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of stimulation in nucleus raphe magnus on neurones in the spinal trigeminal nucleus was studied in decerebrate cats. Short trains of raphe stimulation reduced or abolished the responses of neurones in nucleus oralis and nucleus caudalis to nociceptor stimulation (tooth pulp or cornea) but had a much weaker or insignificant effect on responses to non-noxious inputs (hair movement or low intensity stimulation of the infraorbital nerve). Maximum inhibition was seen 10--50 msec following the raphe stimulation and persisted up to 300 msec. The depression of neuronal responses was paralleled by an increase in the threshold of the jaw-opening reflex evoked by tooth pulp stimulation. The relation to stimulus-produced analgesia is discussed.
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PMID:Inhibitory effects of nucleus raphe magnus on neuronal responses in the spinal trigeminal nucleus to nociceptive compared with non-nociceptive inputs. 52 71

Basal tear production was measured by means of standardized Schirmer strips and 0.5% proparacaine hydrochloride topical anesthesia in 20 patients. Premedication with systemic diazepam (Valium) and atropine sulfate had no effect on basal tear production. General surgical anesthesia resulted in a noticeable depression of basal tear production at 10, 30, and 60 minutes following induction of the anesthesia. It is suggested that prophylactic eye care include both replacement of tears and prevention of mechanical exposure of the cornea during general anesthesia.
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PMID:Decreased basal tear production associated with general anesthesia. 83 95

The usefulness of biochemical studies on effects of light on transparent tissues of the mammalian eye is discussed in relation to the possible role of photobiological phenomena in aging and pathology of the eye. Particular emphasis is on effects of light on interaction between different cellular constituents of the corneal stroma which appear as a factor in regulation of the corneal metabolism. Daylight filtered through the walls of glass vessels was found to depress the incorporation of 14-C glucosamine into keratansulfate fraction of the bovine corneal stroma which appears not to be bound to collagen fibrils as it is extracted by 0.15M NaC1 at 4 degrees C without any morphological change in these fibrils. Since this depression was not found in the absence of the epithelium, secretions by the epithelium of specific substances affecting the keratoyctes are suggested. The possible relation of light effects on the hydration of the cornea is discussed.
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PMID:Some biochemical aspects of light effects on transparent eye tissues. 112 95

Three neonatal calves ranging in age from 4 to 14 days were examined pathologically and bacteriologically. The calves showed depression, anorexia, pyrexia, and difficulty or inability to stand followed by cloudiness of the ocular aqueous humor or cornea. Autopsy revealed congestion, petechiae, and cloudy areas in the meninges. Histologically, the central nervous system (CNS) lesions were prominent and limited to the meninges where fibrinous exudate and infiltrations of neutrophils, macrophages, and lymphocytes were present. There were mild or slight degrees of choroid plexitis and ependymitis. Endophthalmitis was seen as a concurrent lesion in all cases. Fibrinous or fibrinopurulent changes were found in the peritoneum and epicardium as well as in several other organs. Numerous Gram-positive cocci were detected in affected areas of the whole body. Bacteriologically, Streptococcus bovis was isolated from all examined materials consisting of the brain, cerebrospinal fluid, ocular aqueous humor, and several other organs. These results suggest that the lesions were associated with infection of the organism and that the present cases were in the process of septicemia.
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PMID:Clinicopathology of meningoventriculitis due to Streptococcus bovis infection in neonatal calves. 142 May 67

Posterior keratoconus is an unusual abnormality of the cornea generally classified as one of the anterior chamber cleavage anomalies. It is characterized clinically by the presence of a circumscribed or generalized corneal thinning with posterior depression of the cornea and is considered distinct from keratoconus. Although patients with posterior keratoconus may have visual complaints clearly related to their abnormal corneas, the surface topography of these corneas has not been studied in detail. Keratometry and photokeratoscopy provide an incomplete picture of the surface geometry of posterior keratoconus. We utilized computer assisted topographic analysis to study the cornea of a patient with posterior keratoconus. The Topographic Modeling System demonstrated that the patient's cornea showed a central steepened "cone" coincident with the area of circumscribed posterior keratoconus as well as paracentral flattening. This report documents the topographic abnormality in this rare disorder.
Cornea 1992 Jul
PMID:Corneal topography of posterior keratoconus. 142 57

Obstetric forceps pressure strong enough to leave a periorbital depression and corneal injury would probably be severe enough to leave an occipital depression from the opposite forceps blade. The presence of a depression at the correct occipital position would support the diagnosis of forceps injury when the birth history is unknown and the cornea has decompensated enough to make observation of the Descemet's membrane scrolls difficult. We studied six patients with known or suspected obstetric forceps injury to the cornea. Complete ocular examinations included examination for periorbital forceps depressions and posterior skull depressions 180 degrees from the affected cornea (which correlates with the opposite blade of the forceps). All of the patients with Descemet's scrolls had posterior skull depressions. This method of palpation for a contralateral skull depression may assist in the diagnosis of forceps-induced corneal decompensation.
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PMID:Contralateral occipital depression related to obstetric forceps injury to the eye. 152 22

Both delta 9-tetrahydrocannabinol (delta 9-THC) and cannabigerol, two naturally occurring marihuana cannabinoids, produced only a modest fall in intraocular pressure after acute topical application to the eyes of cats. After chronic administration unilaterally to the cornea via Alzet osmotic minipumps and connecting extraocular cannulas, however, a considerable fall in ocular tension amounting to 4 to 7 mm Hg occurred. After systemic administration of delta 9-THC to rats, polyspike discharges appeared in the cortical electroencephalogram initially during wakefulness and behavioral depression. These polyspikes subsequently became evident within rapid eye movement sleep episodes. Cannabigerol was devoid of this effect. After removal of either sympathetic or parasympathetic input to the eyes of cats, the intraocular pressure lowering effect of delta 9-THC was not changed. Neither delta 9-THC nor cannabigerol altered the rate of formation of aqueous humor. On the other hand, both cannabinoids produced a two-to three-fold increase in aqueous outflow facility. These results suggest that cannabigerol and related cannabinoids may have therapeutic potential for the treatment of glaucoma.
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PMID:A comparison of the ocular and central effects of delta 9-tetrahydrocannabinol and cannabigerol. 196 36

In order to study the potential use of ultrasound as a noninvasive system for altering corneal curvature, we used high-density focused ultrasound at a frequency of 4.8 MHz and 7.9 MHz to produce corneal lesions in the rabbit eye. Intensity and duration threshold exposure conditions were determined for the production of minimally visible lesions. Threshold lesions were initially apparent as discrete white opacities resulting from stromal edema and disruption. Light and scanning electron microscopy of higher-energy, suprathreshold lesions revealed more extensive disruption, including the formation of a superficial stromal depression and a larger zone of edema and disorganization surrounding each lesion. Posterior stromal lamellae, endothelium, and Descemet's membrane were intact. Healing and reepithelialization resulted in a smooth corneal surface with no residual opacification. Threshold determinations predict safe exposure levels to the cornea during insonification of other ocular structures. Selective heating of the peripheral cornea using focused ultrasound may be a useful technique for correcting astigmatism.
Cornea 1990 Oct
PMID:Production of corneal lesions using high-intensity focused ultrasound. 207 61

It has been found that D-timolol is equipotent or slightly less potent than L-timolol to lower the intraocular pressure (IOP) in normotensive rabbits, water loaded ocular hypertensive rabbits, alpha-chymotrypsin induced glaucoma rabbits, hypertonic saline infused IOP recovery model of rabbits, normotensive human volunteers, glaucoma patients and ocular hypertensive human individuals. Although L-timolol has been used widely for the treatment of glaucoma and ocular hypertension, it produces numerous side effects including cardiovascular disturbances, asthmatic attack, psychological depression, etc. Since D-timolol has much weaker affinity toward beta-adrenergic receptors, it was found to have 1/80-1/300 the beta-adrenergic blocking potency of L-timolol to block beta-adrenergic receptors in guinea pig tracheal preparations and 1/90 of L-timolol to block beta-adrenergic receptors in guinea pig atrial preparations. As a result, D-timolol showed no subjective nor objective side effects on pupil size, conjunctiva, cornea, blood pressure and pulse rate. Further, D-timolol was reported to increase retinal and choroid blood flow in rabbits without affecting overall ocular blood flow. On the contrary, L-timolol was found to significantly reduce the overall ocular blood flow and retinal and choroid blood flows in rabbits, although it might slightly increase the retinal blood flow in normotensive individuals. D-Timolol was well absorbed across the cornea as L-timolol and produced the duration of action as long as L-timolol. These results indicate that D-timolol could be a better agent than L-timolol for the treatment of glaucoma and ocular hypertension.
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PMID:Development of D-timolol for the treatment of glaucoma and ocular hypertension. 219 94

Three aspects of trigeminal pain are considered: the peripheral mechanisms of pain from teeth and from the cornea, and the role of the trigeminal brainstem nuclei in pain. Pain is probably the only sensation that can be evoked by stimulation of dentin or dental pulp in man. Five nerve-endings enter dentinal tubules from the pulp but do not extend into the outer dentine, which is nevertheless sensitive. In teeth of limited growth in experimental animals, the dental pulp is supplied by A beta, A delta and C fibres and these are associated with two categories of receptor: one responds to cooling and to other stimuli that cause displacement of the contents of the dentinal tubules such as probing and drying the dentine, and the other group responds most vigorously to heating. Some cold sensitive units have A beta fibres and the evidence suggests that stimulation of these is capable of evoking both muscle reflexes and pain and, near threshold, 'pre-pain' sensations. Thermal stimulation of the cornea produces sensations of pain and, with less intense stimuli, irritation, Mechanical stimulation also produces pain but it is not clear whether, below the pain threshold, such stimuli produce touch sensation or some other sensation related to pain. Histologically, the nerve-endings in the corneal epithelium consist of fine, bare processes closely associated with the surface of the epithelial cells. Recordings in experimental animals have shown that many of the receptors respond to several different forms of stimulus and their properties correlate well with those predicted from psychophysical experiments in man. The results of trigeminal tractotomy in man and recordings from the trigeminal brainstem nuclei in anaesthetized animals, have generally indicated that nucleus caudalis is the main relay in the pain pathway from the face and associated structures. Recent observations have, however, shown that tractotomy does not produce complete analgesia of this region and responses to thermal stimulation of teeth and noxious stimulation of other oro-facial tissues have been recorded from the more rostral parts of the brainstem nuclear complex. The surgical procedures employed to set up an animal for stereotaxic recording may induce long-lasting depression in the excitability of neurons in these nuclei, which masks some of their properties. The mechanism of this depression has not been established.
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PMID:Peripheral and central aspects of trigeminal nociceptive systems. 285 85


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