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Given the association between periodontal disease (PdD) and Alzheimer’s disease (AD), we examined correlations between states’ age-adjusted AD mortality rates, AD prevalence, subjective cognitive decline (SCD) prevalence, and oral health data. Data sources include the Centers for Disease Control and Prevention, scientific literature, and oral health rankings formulated by WalletHub.com and Toothbrush.org. Pearson (r) or Spearman (rs) correlation coefficients were generated and evaluated. AD mortality rates correlate with dental visits (r = − 0.50, p = 0.0003), partial (r = 0.39, p = 0.005) or total (r = 0.44, p = 0.001) edentulism, WalletHub.com (rs = 0.30, p = 0.03) and Toothbrush.org (rs = 0.35, p = 0.01) rankings. AD prevalence correlates with dental visits (r = − 0.30, p = 0.03), partial (r = 0.55, p = 0.00003) or total (r = 0.46, p = 0.0009) edentulism, prevalence of any (r = 0.38, p = 0.006) or severe-stage (r = 0.46, p = 0.0009) PdD, and WalletHub.com (rs = 0.38, p = 0.006) rankings. SCD prevalence in adults aged ≥ 45 years correlates with dental visits (r = − 0.69, p s = 0.53, p = 0.00008) and Toothbrush.org (rs = 0.60, p

Purpose To propose a methodology for ranking U.S. clinical ophthalmology programs which utilizes an existing framework of both objective structural (or resource) information and outcome data as well as subjective reputational scores currently used by U.S. News & World Report for most clinical specialties. Design Evidence-based manuscript. Topic The U.S. News & World Report annual “Best Hospital Rankings by Specialty” provides the public with information regarding the relative strengths of U.S. medical and surgical departments in providing care and treatments for patients with complex diseases. For most medical and surgical specialties, these rankings are determined by considering a combination of objective structural (or resource) information and outcome data along with subjective reputational scores. Clinical Relevance In ophthalmology, U.S. News & World Report annual rankings are currently generated only from subjective reputational scores submitted by a small number of voting ophthalmologists. No objective clinical or outcome data are considered. Literature Reviewed Methodology for determining “Best Hospital Rankings by Specialty” utilized by RTI International on behalf of U.S. News & World Report. Results The ranking system of U.S. departments of ophthalmology presently employed by U.S. News & World Report presents an incomplete picture of the relative strengths and weaknesses of the departments listed. Conclusion With the changes in health insurance that increasingly shift decision-making responsibility and cost to consumers, providing mechanisms to allow the public to make informed decisions is an emerging imperative for ophthalmology and other specialties. Revision of the current “reputation-only” ranking system used for ophthalmology to also include objective clinical and outcome data would benefit patients by providing more accurate and impartial information on which to base their eye care decisions.

The aim of this study was to determine the effect of prostaglandin analog use on postoperative intraocular pressure (IOP) and treatment success following selective laser trabeculoplasty (SLT).Records from 113 eyes with open angle glaucoma who underwent SLT were reviewed retrospectively. Eyes were categorized as to whether they were receiving a topical prostaglandin analog (n = 78) or other classes of glaucoma medications (n = 35) before and following SLT. IOP was measured before (baseline) and at 1 h, 1 day, 1 week, and 1 month following SLT.Baseline IOP (+/-standard error [SE]) did not differ between prostaglandin analog users (18.0 +/- 0.48 mmHg) and nonusers (17.5 +/- 0.71 mmHg). One (1) month after SLT, average IOP decrease (+/-SE) was greater (P0.02) among prostaglandin analog users (3.4 +/- 0.4 mmHg), compared to nonusers (1.6 +/- 0.5 mmHg). Also at 1 month, average percent IOP decrease (+/- SE) was greater (P0.015) among prostaglandin analog users (16.5 +/- 2.0%), compared to nonusers (7.9 +/- 2.7%). At 1 h, 1 day, and 1 week after SLT, there were no differences in average IOP decrease or percent IOP decrease between prostaglandin analog users and nonusers. The percentage of eyes with a 20% or greater decrease in IOP was greater (P0.015) among prostaglandin analog users (44.9%), compared to nonusers (22.9%), 1 month after SLT. Also, 48.7% of prostaglandin analog users had an IOP decrease of 3 mmHg or greater, compared to 31.4% of nonusers, 1 month after SLT (P0.05). Retreatment rate among prostaglandin analog users (11.5%) was less (P0.005) than nonusers (34.3%).Prostaglandin analog use during the perioperative period prior to and 1 month after SLT is associated with greater average IOP decrease and percent IOP decrease 1 month postoperatively, compared to eyes not receiving these agents. Prostaglandin analog use is also associated with a greater likelihood of treatment success and a lesser likelihood of requiring retreatment 1 month postoperatively.

To evaluate the effect of a single treatment of contact diode laser transscleral cyclophotocoagulation (TSCP) on intraocular pressure (IOP) in patients with refractory glaucoma and perform a historical meta-analysis of the relationship between successful IOP control and various laser parameters.Clinical data for 47 eyes of 43 patients who underwent a single session of contact diode laser TSCP (power of 2000 mW, exposure time of 2 seconds and 25.6 average applications) for refractory glaucoma at Pasco Eye Institute between 1996 and 2001 were reviewed. Baseline IOP was compared with the postoperative IOP at 1 month, 3 to 6 months, and 1 year. Snellen visual acuity and the number of glaucoma medications being used 3 to 6 months postoperatively were compared with baseline. Complications were also evaluated. The relationship between successful IOP control and various laser parameters (energy applied per eye, energy per laser application, power, exposure time and number of laser applications) was examined using the results of this study and previous investigations.The mean +/- standard deviation (SD) baseline IOP was 29.4 +/- 10.9 mm Hg. Diode laser TSCP decreased average IOP to 15.7 +/- 12.0 mm Hg at 1 month, 16.3 +/- 4.2 mm Hg at 3 to 6 months, and 16.2 +/- 4.8 mm Hg at 1 year, postoperatively. This represents an IOP reduction of approximately 45%. The percentage of patients maintaining a postoperative IOP of21 mm Hg was 95.7% at 1 month, 92.1% at 3 to 6 months, and 94.4% at 1 year after TSCP. At the 3 to 6 month postoperative visit, the average +/- SD change in Snellen visual acuity (-0.5 +/- 1.1 lines) and the number of glaucoma medications used did not differ significantly from baseline. Combined analysis of the results of this study and previous studies reveals a linear, direct correlation (r = 0.91) between the percentage of patients achieving a successful outcome (defined as a final IOP21 or 22 mm Hg) and the total energy delivered to the ciliary body during the treatment session.Diode laser TSCP is a safe and highly effective method for lowering IOP in patients with uncontrolled glaucoma. Higher total energy levels in a given treatment session appear to be associated with increased success as defined by the percentage of patients achieving an IOP21 or 22 mm Hg, without an increased risk of additional complications or vision loss.

To study the effect of monotherapy with latanoprost 0.005% on intraocular pressure (IOP) in a prospective nonrandomized clinical trial of patients newly diagnosed with steroid-induced secondary open-angle glaucoma.Eight patients (16 eyes) with newly diagnosed steroid-associated secondary open-angle glaucoma were prescribed latanoprost 0.005% once a day in each eye. The initial IOP before treatment served as an internal control for each eye. Intraocular pressure was remeasured after 1 month of monotherapy with latanoprost. Investigators (WJS) were blinded to initial IOP at the time of remeasurement. After discontinuation of steroids, IOP was rechecked. If IOP was stable, latanoprost was discontinued. Intraocular pressure was rechecked 2 to 4 weeks later to confirm an association with steroid use.Intraocular pressure was significantly decreased after treatment with latanoprost (18.3 +/- 2.8 mm Hg) compared with initial IOP (25.3 +/- 9.1 mm Hg). This change represented a 28% decrease in IOP compared with baseline levels. Average IOP after discontinuation of steroids and latanoprost (17.3 +/- 1.4 mm Hg) did not differ from IOP measured during treatment with latanoprost, but it was significantly less than the initial IOP before treatment. No adverse effects were noted.Monotherapy with latanoprost is safe and effective in patients with steroid-induced glaucoma. Advantages include lack of systemic side effects and convenient once-daily dosing.

To compare the effect of latanoprost 0.005% with that of a placebo (balanced salt solution [BSS]) applied after phacoemulsification on intraocular pressure (IOP).Pasco Eye Institute, New Port Richey, Florida, USA.A group of patients having cataract extraction by phacoemulsification was randomized following surgery to receive one drop of latanoprost 0.005% (1.5 micrograms) or a placebo (BSS). Exclusion criteria included ocular diagnosis in addition to cataract, previous eye surgery, history of glaucoma, previous use of glaucoma medications, or vitreous loss during surgery. Standard phacoemulsification was performed through a scleral tunnel approach and a one-piece, poly(methyl methacrylate) intraocular lens implanted in the capsular bag. Approximately 24 hours after surgery, IOP was measured with a Goldmann applanation tonometer by the surgeon. The anterior chamber reaction was qualitatively graded from 1+ to 4+.The study included 103 eyes (latanoprost = 53; control = 50). Latanoprost treatment resulted in significantly lower postoperative (IOP) (16.4 mm Hg +/- 3.7 [SD]) than preoperative IOP (17.9 +/- 3.0 mm Hg) (P.025). There was no decrease in postoperative IOP in the control group (18.2 +/- 3.5 mm Hg) compared with preoperative IOP (18.3 +/- 2.6 mm Hg). When two groups were compared, postoperative IOP after treatment with latanoprost was significantly less than control IOP (P.01). Preoperative IOP was not significantly different in the placebo and latanoprost groups. Anterior chamber reaction was not increased by latanoprost; it averaged 1+ in both groups.Latanoprost may pharmacologically enhance uveoscleral outflow immediately after cataract extraction. In this study, latanoprost was a safe, effective method of reducing postoperative IOP.

In the frog Xenopus laevis, the isthmotectal projection, which relays input from the ipsilateral eye, exhibits anatomical reorganization following surgical eye rotation performed during tadpole stages while the isthmotectal projection in the frog Rana pipiens fails to show reorganization. This plasticity has been shown to be dependent upon activation of the N-methyl-D-aspartate (NMDA) receptor located on tectal cell dendrites. The reorganization process in Xenopus is hypothesized to employ a Hebbian mechanism requiring correlated firing of ipsilateral and contralateral inputs to a given tectal cell; when an ipsilateral axon synapses onto a tectal cell that receives input from a contralateral axon with a matching receptive-field location, the correlation in activity triggers stabilization of the ipsilateral synapse. However, in neither Xenopus nor Rana do ipsilateral and contralateral inputs begin to fire simultaneously in response to a given visual stimulus; the ipsilateral input is delayed because it reaches the tectum indirectly, through a polysynaptic relay via the opposite tectum and nucleus isthmi. The objective of this experiment was to test whether there is a significant difference in this intertectal delay between Xenopus laevis and Rana pipiens in order to determine whether intertectal delay could be a contributing factor in this species-specific ability to exhibit visual plasticity. We have found that intertectal delay is 26.16 ms longer in Rana pipiens (36.53 ms) than in Xenopus laevis (10.37 ms).

In the tectum of Rana pipiens , responses to repeated flashes of light to the ipsilateral eye display considerable habituation. We have employed the plant lectin concanavalin A (Con A), which can diminish desensitization of glutamate receptors in vitro, in order to examine whether desensitization of glutamate receptors contributes to this habituation. The ipsilateral eye's projection reaches each tectal lobe indirectly, being relayed from the opposite tectal lobe via the tecto-isthmo-tectal projection. One of the sites along this pathway at which habituation may take place is the retinotectal synapse, where glutamate is a putative transmitter. Pretreatment of one lobe of the tectum with Con A significantly diminished the habituation of responses recorded in the other tectal lobe to light offset, with less of an effect on responses to light onset. These data suggest that OFF habituation may reflect glutamate receptor desensitization at the retinotectal synapse. In contrast, recordings from retinotectal terminals indicate that a primary site of habituation of ON responses is within the retina.

Each tectal lobe of Xenopus forgs receives two topographic maps, one via the ipsilateral eye and one via the contralateral eye. The alignment of the ipsilateral map with the contralateral map depends upon bincoular visual input during a critical period that extends from late tadpole to early juvenile stages. Rotation of one eye during the critical period leads to reorganization of the ipsilateral map, which eventually comes back into alignment with the contralateral map despite the abnormal eye position. The ipsilateral eye's map initially develops as if there had been no alteration in eye position; there is a delay of 4–6 weeks before reorganization can be detected by electrophysiological mapping. In this paper, the possible role of the NMDA receptor in the delay in reorganization is addressed. The degree of NMDA receptor activation may need to be above some threshold level to trigger reorganization. If NMDA receptor activation normally is below that level until after the first month postmetamorphosis, then exogenous NMDA might boost the process sufficiently to start the reorganization process sooner than usual. In order to test this possibility, the left eye of tadpoles was rotated and NMDA was applied to the right tectal lobe for 3–5 weeks, starting at 1 week postmetamorphosis. Electrophysiological mapping demonstrated that reorganization takes place more rapidly than in untreated forgs or frogs treated with vehicle only. This result is consistent with the interpretation that the activation of the NMDA receptor is a rate-limiting step in the activity-dependent matching of binocular maps in Xenopus tectum. 1994 John Wiley & Sons, Inc.

Matrix metalloproteinases (MMPs) are a family of enzymes that act to degrade extracellular matrix (ECM) molecules, such as collagen, elastin, and gelatin. The glaucoma medication latanoprost, and possibly other topical prostaglandin analogs, increase uveoscleral outflow and lower intraocular pressure (IOP) in primary open-angle glaucoma (POAG) by activating MMPs 1, 2, 3, and 9 in the ciliary body. It has been reported that latanoprost may also gain access to the posterior segment and induce cystoid macular edema, although the mechanism is unknown. In the choroid, activation of some of the same subtypes of MMPs (particularly subtypes 2 and 9) has been implicated in the formation of choroidal neovascular membranes (CNVMs) in age-related macular degeneration (AMD). This study examined whether topical prostaglandin analog use is associated with a greater risk of CNVM formation in patients diagnosed with both AMD and POAG.A retrospective record review was performed to identify patients with a concurrent diagnosis of AMD and POAG between 1998 and 2004. Four hundred and eighty-four (484) eyes were identified and grouped as wet (n = 65) or dry (n = 419) AMD. Prostaglandin usage was compared between the two groups. Usage of other glaucoma medications was also compared. A minimum of 1 year of topical glaucoma medication was required for inclusion in the study. Exclusion criteria included a history of CNVM prior to starting glaucoma medications and a previous history of glaucoma surgery.Fifty-six percent (56%) of dry AMD and 62% of wet AMD eyes were using a topical prostaglandin (P0.10; not significant). Analysis of specific topical prostaglandin analog usage in the wet versus dry AMD groups revealed no statistically significant differences in the percentage of eyes treated with latanoprost (37.7% versus 41.5%), bimatoprost (12.9% versus 10.8%), or travoprost (9.2% versus 5.3%), respectively. No significant differences in the use of other glaucoma medications were observed between the two groups.No association between long-term topical prostaglandin use and CNVM development was found in patients with AMD and POAG.

The purpose of this study was to determine the percentage of treatment-naive glaucoma patients initially treated with latanoprost monotherapy who do not respond with a clinically meaningful reduction of intraocular pressure (IOP). A database search of previously untreated patients with newly diagnosed primary open angle glaucoma, ocular hypertension or pseudoexfoliative glaucoma initially treated with once-daily latanoprost, 0.005% monotherapy was conducted. Charts were randomly reviewed until 20 patients meeting inclusion criteria were identified. Baseline IOP was compared to IOP measured 1 to 3 months after the initiation of therapy. Intraocular pressure (+/- S.D.) following latanoprost treatment (17.0 +/- 3.5 mm Hg) was significantly (p < 0.0005) less than baseline (23.9 +/- 4.2 mm Hg) in the study population. Based on our criteria of a clinically meaningful decrease in IOP, we identified a subgroup of patients (25%) who were non-responsive to latanoprost monotherapy. Non-responders did not differ from responders with regard to baseline IOP or age. Although latanoprost may be an effective IOP-lowering agent in most patients, there exists a subgroup of patients who are unresponsive. As with any topical glaucoma agent, IOP must be monitored regularly to confirm effectiveness.

Purpose To evaluate the outcomes and possible benefit of surgery performed on adults for anterior segment trauma sustained during childhood. Setting Private practice. Methods A retrospective review of patient records was performed. Adult patients who had anterior segment surgery for injuries that occurred during childhood were identified. The surgical outcomes were evaluated to determine whether intervention was beneficial in this subgroup of patients. Results Six patients were identified. Preoperative best corrected visual acuity (BCVA) was 20/200 or worse in all patients. After surgery, the BCVA in 3 patients had improved to 20/30 or better and in 1 patient, to 20/60. The other 2 patients had less improvement; however, each noted subjective improvement in vision. No major intraoperative or postoperative complications occurred. Conclusion In the absence of evidence of accompanying posterior segment trauma, surgery in adults to correct anterior segment damage from childhood trauma was safe and often beneficial.

Objective: In the past, evidence of endogenous fungal endophthalmitis has been used as a guide to initiating potentially toxic antifungal therapy in patients with systemic fungal infections. Recently, however, a trend has developed to provide patients with antifungal therapy at the first evidence of fungal infection. The authors' study evaluates the incidence of endogenous fungal endophthalmitis in this setting. Design: The design is a retrospective review of the medical records of patients examined by the inpatient ophthalmology consultation service to rule out endogenous fungal endophthalmitis between January 1994 and April 1996 at the University of Michigan Hospitals, Ann Arbor, Michigan. Participants: Two hundred fourteen eyes of 107 patients with a diagnosis of systemic fungal infection were studied. Intervention: A review of medical records was performed. Main Outcome Measures: The findings of the ocular examination, the presence of risk factors for disseminated fungal infection, the type of antifungal therapy, and the source and identity of the isolated fungus were recorded. Results: The majority of patients examined had either fungal growth from blood cultures or evidence of deep tissue fungal infection. All patients in the study were at risk for fungal disease with each having at least one risk factor for disseminated fungal infection. Of the patients examined, 93.4% already were receiving systemic antifungal therapy at the time of ophthalmologic consultation. Only 3 (2.8%) of the 107 patients examined had chorioretinal findings consistent with early endogenous fungal endophthalmitis. None had intravitreous involvement, and the ocular findings did not change the course of therapy. Conclusions: Early systemic treatment of deep tissue fungal infection appears to dramatically decrease the incidence of endogenous fungal endophthalmitis.

1. The tectum of Xenopus receives visuotopic input from both eyes. The contralateral eye's projection reaches the tectum directly, via the optic nerve. The ipsilateral eye's projection reaches the tectum indirectly, via the nucleus isthmi and isthmotectal projection. 2. Because of the multi-synaptic nature of the ipsilateral pathway, there is an inherent delay between the time that information from the contralateral eye reaches the tectum and the time that information from the ipsilateral eye arrives at the tectum. The length of the intertectal delay is a function of the latencies of the contralateral and ipsilateral pathways. 3. The length of this intertectal delay has functional, as well as developmental, implications with regard to the role of N-methyl-D-aspartate receptors in tectal cell activity and development of orderly synaptic connections. 4. We have found that the latencies of the contralateral and ipsilateral pathways exhibit a seasonal variation, increasing during the winter months. The increases of both latencies during the winter were of similar magnitude, indicating that there were no significant changes in intertectal delay. The seasonal alteration in contralateral latency was not affected by dark-rearing and was affected to only a minor extent by a week-long alteration of ambient temperature.

Visually elicited activity contributes to the formation of orderly connections in the optic tectum of frogs. Glutamate receptors of the N -methyl- d -aspartate class participate in this process. Blocking those receptors interferes with activity-dependent refinement of maps in normal frogs and of ocular dominance bands in surgically produced animals with three eyes. Chronic application of N -methyl- d -aspartate sharpens the bands. The possibility that 5-amino-phosphonovaleric acid depresses tectal responsiveness was motivation for studying the effects of 5-amino-phosphonovaleric acid and N -methyl- d -aspartate applied both chronically and acutely. We evaluated tectal responsiveness to visual input by presenting flashes of light to one eye and recording responses in the ipsilateral tectal lobe. This method reveals the output of the tectal cells contralateral to the stimulated eye. These cells project via the nucleus isthmi to the opposite tectal lobe. We also mapped the receptive field dimensions of the crossed isthmotectal axons. Our results show that acute topical application of 500 μM or 1 mM N -methyl- d -aspartate dramatically increases spontaneous activity, while 100 μM N -methyl- d -aspartate causes little change. Chronic treatment with N -methyl- d -aspartate at a low dose (estimated to be in the micromolar range) shown to influence retinotectal mapping, reduces response latencies but produces no statistically significant changes in tectal cell firing rates or receptive field size. Acute application of 5-amino-phosphonovaleric acid produces complex results: 10 μM produces no changes in firing, 100 μM 5-amino-phosphonovaleric acid decreases firing, and doses of 500−100 μM increase the firing. Chronic micromolar 5-amino-phosphono-valeric acid, at doses capable of blocking activity-dependent refinement of retinotectal maps, decreases spontaneous firing and the latency of visually evoked bursts but otherwise produces no notable changes in tectal cell responses. Our data support the hypothesis that chronic treatment with N -methyl- d -aspartate and 5-amino-phos-phonovaleric acid influence retinotectal development by affecting the N -methyl- d -aspartate receptor specifically and not by causing overall changes in tectal activity.

In the South African clawed-toed frog Xenopus laevis, visual experience plays a crucial role in the formation of matching binocular maps in the tectum. The ipsilateral eye's projection, relayed through the crossed isthmotectal projection, displays marked plasticity in response to altered visual input during a critical period of development. This plasticity and the events responsible for the end of the critical period are mediated by N-methyl-D-aspartate (NMDA) receptor function. We have previously reported that chronic blockade of tectal NMDA receptors with the NMDA antagonist 5-amino-phosphonovaleric acid (APV) prevents plasticity of the crossed isthmotectal projection during the critical period, while chronic treatment with NMDA restores this plasticity after the end of the critical period. These results raise the question of whether the effects on plasticity are due to changes in electrical responsiveness of the treated tissue. In this study, we have quantitatively assessed the actions of APV and NMDA on certain aspects of tectal cell activity in Xenopus during and after the critical period by recording the output of the nucleus isthmi cells that are activated by the tectum after three weeks of treatment. We have found that chronic APV treatment does not alter tectal output, as indicated by the firing of isthmotectal axons, during the critical period and that chronic NMDA treatment increases tectal output in postcritical period Xenopus. Tectal output does not differ between normal Xenopus during and after the end of the critical period.These results indicate that the effect of APV on blocking isthmotectal plasticity is not due to a nonspecific inhibition of the segment of the retinotectal relay that activates the nucleus isthmi. The enhancement of tectal output in postcritical period Xenopus by chronic NMDA treatment may promote the effectiveness of NMDA in restoring isthmotectal plasticity after the end of the critical period, but the finding that tectal activity does not differ between normal Xenopus during and after the critical period implies that a reduction in tectal activity in not the cause of the loss of plasticity at the end of the critical period.

The mechanisms underlying the development of proper topographic registration of binocular maps in the tectum of Xenopus laevis involve correlation of activity patterns of ipsilateral and contralateral inputs. Recent evidence implicates NMDA-type glutamate receptors in this process. In general, NMDA receptors are considered to function optimally when there are multiple, simultaneous excitatory inputs to a dendrite. In the binocular system of the frog, however, the ipsilateral eye's response to a visual stimulus reaches the tectum later than the contralateral eye's response. The reason for this delay is that the ipsilateral pathway to the tectum is indirect, involving a relay in the opposite tectum and nucleus isthmi. In this paper, we evaluate the duration of the delay between arrival of contralateral and ipsilateral input in response to cessation of light and we also gauge the extent of temporal overlap in responses of the two inputs. We find that the average delay is about 10 ms and that this delay is not significantly different during the critical period vs later in development. The temporal overlap is 40–60 ms in duration. We conclude that the intertectal delay does not prevent a substantial period of simultaneous firing of ipsilateral and contralateral inputs in response to sudden changes in illumination. Therefore, the firing patterns of these afferents are compatible with a mechanism of activity-dependent alignment of binocular maps in the tectum.

Visual input during a critical period of development plays a major role in the establishment of orderly connections in the developing visual system. In Xenopus laevis, the matching of visual maps from the two eyes to the optic tectum depends on binocular visual input during the critical period, which extends from late tadpole to early juvenile stages. Alterations in eye position, which produce a mismatch of the tectal maps, normally evoke a compensatory adjustment in the map of the ipsilateral eye only during the critical period. However, continuous application of the glutamate receptor agonist N-methyl-D-aspartate (NMDA) after the normal end of the critical period restores this ability to realign the visual map.

ATP hydrolysis activity and calcium transport activity were determined on light sarcoplasmic reticulum from rabbit skeletal muscle. The effects of two buffers, TRIS and HEPES, were compared. Titration of TRIS into sarcoplasmic reticulum preparations in HEPES provided evidence for TRIS inhibition of ATPase activity and TRIS stimulation of calcium transport activity.

Glutamate receptors appear to play a key role in several forms of experience-dependent modification of both the strength of synapses and synaptic connectivity. In developing Xenopus frogs, the connections made by isthmotectal axons relaying visual input from the eye to the ipsilateral tectum are markedly influenced by the visual activity of contralateral retinotectal axons, and normal binocular visual input is necessary in order for the ipsilateral visuotectal map to come into register with the contralateral map. We have tested whether NMDA receptors play a role in establishment of the topographic matching of binocular maps during development. We have examined the effects of chronic treatment of tectum with either the receptor agonist NMDA or the antagonists APV or CPP applied throughout early postmetamorphic life using subpial implants of drug-impregnated elvax. Both antagonists blocked the matching of the ipsilateral map to the contralateral map, while NMDA permitted such matching. Our data therefore indicate that NMDA receptors are involved in the experience-dependent establishment of matching binocular maps during development.