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The lead pyrophosphate precipitation technique was used to visualize adenylate cyclase activity with the electron microscope in unfixed electric organ and synapto-somes of Torpedo marmorata, with special attention to presynaptic membranes. Specificity of the deposition of reaction product was ensured by using 5′-adenylyl imidodiphosphate as substrate and 5′-guanylyl imidodiphosphate and sodium fluoride as activators. Under suitable conditions a reaction product was deposited on the Schwann cell, on presynaptic vesicles, on the inner side of membranes of cisternae and on glycogen granules of the presynaptic region of the endplate. In some cases, a precipitate was also found on postsynaptic membranes of the synaptic cleft and on mitochondria. In isolated synaptosomes localization of the reaction product was identical with that of minced tissue. However, most strikingly, on presynaptic membranes no precipitate was ever found, neither in pieces of electric organ nor in isolated synaptosomes. Furthermore, the extended membrane system of the postsynaptic region of the electroplax remained always free of leed pyrophosphate precipitate. [ABSTRACT FROM AUTHOR]

Study Objective: We assess the impact of emergency department (ED) pharmacists on reducing potentially harmful medication errors., Methods: We conducted this observational study in 4 academic EDs. Trained pharmacy residents observed a convenience sample of ED pharmacists' activities. The primary outcome was medication errors recovered by pharmacists, including errors intercepted before reaching the patient (near miss or potential adverse drug event), caught after reaching the patient but before causing harm (mitigated adverse drug event), or caught after some harm but before further or worsening harm (ameliorated adverse drug event). Pairs of physician and pharmacist reviewers confirmed recovered medication errors and assessed their potential for harm. Observers were unblinded and clinical outcomes were not evaluated., Results: We conducted 226 observation sessions spanning 787 hours and observed pharmacists reviewing 17,320 medications ordered or administered to 6,471 patients. We identified 504 recovered medication errors, or 7.8 per 100 patients and 2.9 per 100 medications. Most of the recovered medication errors were intercepted potential adverse drug events (90.3%), with fewer mitigated adverse drug events (3.9%) and ameliorated adverse drug events (0.2%). The potential severities of the recovered errors were most often serious (47.8%) or significant (36.2%). The most common medication classes associated with recovered medication errors were antimicrobial agents (32.1%), central nervous system agents (16.2%), and anticoagulant and thrombolytic agents (14.1%). The most common error types were dosing errors, drug omission, and wrong frequency errors., Conclusion: ED pharmacists can identify and prevent potentially harmful medication errors. Controlled trials are necessary to determine the net costs and benefits of ED pharmacist staffing on safety, quality, and costs, especially important considerations for smaller EDs and pharmacy departments., (Copyright (c) 2009 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.)

Background: Despite existing consensus guidelines, venous thromboembolism (VTE) prophylaxis is underused in high-risk hospitalized patients. The present study evaluated the effects of an electronic alert to the responsible physician in a cohort of hospitalized high-risk patients not receiving VTE prophylaxis., Methods: The absence of VTE prophylaxis orders in hospitalized patients at high-risk for VTE triggered an electronic alert to the responsible physician. We studied a cohort of 866 patients whose physicians were alerted that their patients were at high-risk but receiving no VTE prophylaxis. The electronic alert recommended that the responsible physician order preventive measures. We followed each patient for 90 days to determine whether imaging-confirmed symptomatic VTE occurred., Results: 9,527 patients were identified as high-risk for VTE. 9% (866) were not receiving prophylaxis, compared with 18% in the intervention arm of a previous randomized trial (P < 0.001). In our current cohort study, 82% (713) of patients were Medical Service patients. Physician response to alerts resulted in prophylactic measures for 37.7% of those alerted. Symptomatic VTE at 90 days occurred in 5.1% of patients in the present cohort group., Conclusion: Implementation of a computer alert program increased prophylaxis rates. However, the majority of alerted physicians in the cohort study did not order VTE prophylaxis despite the alerts. Therefore, novel strategies must be employed to further improve the use of VTE prophylaxis in hospitalized high-risk patients, especially in Medical Service patients.

Complementary and alternative medicine (CAM) is a multibillion-dollar industry. Almost half of the American population uses some form of CAM, with many using them in addition to prescription medications. Most patients fail to inform their health care providers of their CAM use, and physicians rarely inquire. Annually, thousands of dietary supplement-induced adverse events are reported to Poison Control Centers nationwide. CAM manufacturers are not responsible for proving safety and efficacy, because the Food and Drug Administration does not regulate them. However, concern exists surrounding the safety of CAM. A literature search using MEDLINE and EMBASE was undertaken to explore the impact of CAM on renal function. English-language studies and case reports were selected for inclusion but were limited to those that consisted of human subjects, both adult and pediatric. This review provides details on dietary supplements that have been associated with renal dysfunction and focuses on 17 dietary supplements that have been associated with direct renal injury, CAM-induced immune-mediated nephrotoxicity, nephrolithiasis, rhabdomyolysis with acute renal injury, and hepatorenal syndrome. It is concluded that it is imperative that use of dietary supplements be monitored closely in all patients. Health care practitioners must take an active role in identifying patients who are using CAM and provide appropriate patient education.

Purpose: Apoptosis is the final common death pathway of photoreceptors in light-induced retinal degeneration and in several animal models for retinal dystrophy. To date, little is known about gene regulation of apoptosis in the retina. The expression of the immediate early gene c-fos is upregulated concomitant with apoptosis in light-induced photoreceptor degeneration and in the rd mouse, an animal model for inherited retinal degeneration. In a recent study it was shown that c-Fos is essential for light-induced apoptosis of photoreceptors in vivo. To determine whether c-Fos is also involved in the apoptotic pathway of inherited retinal degeneration, rd/rd, c-fos -/- double-mutant mice have been generated., Methods: Double-mutant mice (rd/rd, c-fos -/-) were crossbred from c-fos+/- mice and rd/rd mice. Their genotype was determined by polymerase chain reaction analysis of genomic DNA. Wild-type control mice and homozygous rd mice were killed at 2-day intervals from postnatal day (P)9 through P21. Double-mutant mice were killed at postnatal days P9, P11, P13, P15, and P21. To determine levels of apoptosis in the retina, eyes were enucleated and processed for light microscopy and in situ nick-end labeling. Total retinal DNA was extracted from isolated retinas for DNA fragmentation analysis., Results: Morphologic, histochemical, and biochemical analyses showed that the time course of apoptosis and the outcome of photoreceptor degeneration in rd/rd, c-fos-/- double-mutant mice was indistinguishable from that in rd mice carrying functional c-fos., Conclusions: These data suggest that in contrast to its role in light-induced photoreceptor degeneration, c-Fos is not essential for apoptosis in the rd mouse.

Background: Apoptosis is a gene-regulated mode of cell death which gains increasing importance in retinal pathologies such as retinitis pigmentosa, retinal detachment and proliferative vitreoretinopathy. A better understanding of the regulation of apoptosis could imply the means to reduce photoreceptor cell death and thereby provide therapeutic strategies to influence the time course of retinal diseases. Previous studies in our laboratory demonstrated that light induces apoptosis in the rat retina in vivo as a function of light dose. In several cell systems, oxidative stress including oxygenated metabolites of arachidonic acid (AA) was found to evoke apoptosis. We have observed a light-elicited release of AA and the subsequent formation of its metabolites in the rat retina. Therefore, AA and its metabolites appeared to be suitable candidates for the induction of apoptosis during light exposure., Materials and Methods: Isolated rat retinas were incubated for 60, 120 and 180 min, respectively, with and without the addition of 30 mumol 5S-hydroperoxyeicosatetraenoic acid (5-HPETE). Retinas were then processed for light- and electron microscopy and examined for the morphological signs of apoptosis. The rate of apoptosis in the outer nuclear layer was assessed quantitatively., Results: 5S-HPETE induces apoptosis of photoreceptors in the rat retina in vitro. Quantitative analysis revealed a significant increase in the rate of apoptosis of 5S-HPETE-treated retinas when compared to untreated controls., Conclusion: Arachidonic acid metabolites released upon light exposure may represent messenger candidates for apoptosis in the retina.

Apoptosis is a genetically regulated form of cell death. Individual cells show condensed nuclear chromatin and cytoplasm, and biochemical analysis reveals fragmentation of the DNA. Ensuing cellular components, apoptotic bodies, are removed by macrophages or neighboring cells. Genes involved in the regulation of apoptosis as well as stimuli and signal transduction systems, are only beginning to be understood in the retina. Therefore, we developed a new in vivo model system for the investigation of events leading to apoptosis in the retina and the pigment epithelium. We induced apoptosis in retinal photoreceptors and the pigment epithelium of albino rats by exposure to 3000 lux of diffuse, cool white fluorescent light for short time periods of up to 120 minutes. Animals were killed at different time intervals during and after light exposure. The eyes were enucleated and the lower central retina was processed for light- and electron microscopy. DNA fragmentation was analysed in situ by TdT-mediated dUTP nick-end labeling (TUNEL) or by gel electrophoresis of total retinal DNA. We observed that the timing of apoptosis in the photoreceptors and pigment epithelium was remarkably different, the pigment epithelium showing a distinct delay of several hours before the onset of apoptosis. In photoreceptors, apoptosis was induced within 90 minutes of light exposure, with the morphological appearance of apoptosis preceding the fragmentation of DNA. In the pigment epithelium, the morphological appearance of apoptosis and DNA fragmentation were coincident. Different regulative mechanisms may lead to apoptotic cell death in the retinal photoreceptors and pigment epithelium. This in vivo model system will allow measurement of dose-responses, a potential spectral dependence and the molecular background of apoptotic mechanisms in the retina.

Apoptotic cell death in the retina was recently demonstrated in animal models of the hereditary human retinal dystrophy known as retinitis pigmentosa. Although recent evidence indicates that the proto-oncogene c-fos is a mediator of apoptosis, its precise role is unclear. In fact, under some conditions, c-fos may even protect against apoptotic cell death. In the retina, c-fos is physiologically expressed in a diurnal manner and is inducible by light. We previously observed a light-elicited, dose-dependent apoptotic response in rat photoreceptors. To determine whether c-fos is involved in the light-induced apoptotic pathway we have used control mice and mice lacking c-fos. We found that following dark adaptation and two hours of light exposure both groups of animals exhibited only a few apoptotic cells. However, at 12 and 24 additional hours after light exposure, apoptosis increased dramatically in controls but was virtually absent in those mice lacking c-fos. Therefore, c-fos is essential for light-induced apoptosis of photoreceptors. Notably, c-fos is continuously upregulated concomitant with apoptotic photoreceptor death in our system and in animal models of retinitis pigmentosa (Agarwal, N. et al., Invest. Ophthalmol. Vis.Sci. Suppl. 36, S638 and Rich, K.A. et al., Invest. Ophthalmol. Vis. Sci. Suppl. 35, 1833). Inhibition of c-fos expression might therefore represent a novel therapeutic strategy to retard the time course of retinal dystrophies and light-induced retinal degeneration.

Low intensity diffuse white fluorescent light (1,000 lx for 2 h) exclusively induced photoreceptor damage in the inferior retina of albino rats; the temporal retina showed extensive damage, whereas the nasal retina revealed threshold lesions prior to recovery. To expand our morphological data, further experiments were undertaken to determine if glial fibrillary acidic protein (GFAP) expression was associated with the regions of photoreceptor damage. To follow the time course of GFAP expression, immunoblot analysis was carried out on retinal homogenates of dark-adapted (control) rats and light-exposed rats returned to cyclic light for 0 h, 1, 2, 3 and 6 days. A significant twofold increase in GFAP immunoreactivity over controls was observed in the retinas of light-exposed rats returned to cyclic light for 6 days. Using an indirect immunohistochemical method, retinal sections of the control and light-exposed rats allowed to recover for 6 days were stained for GFAP. GFAP immunoreactivity was localised to the astrocytes and Müller cells. Moreover, GFAP staining in Müller cells in the retinas of control animals was uniformly restricted to rare end-feet. In contrast, a gradient of GFAP immunoreactivity was observed in experimental rats, rising from the superior retina to the inferior temporal quadrant; the GFAP staining in the inferior nasal quadrant was intermediate. Thus, GFAP immunoreactivity was proportional to photoreceptor damage. Interestingly, no GFAP induction could be demonstrated in the pineal glands of light-exposed rats.

Purpose: Previous studies have shown that ingestion of fish oil (FO) containing a high proportion of n-3 polyunsaturated fatty acids increases the susceptibility of cellular membranes to oxidative damage in various tissues. In the retina, lipid peroxidation is thought to be a major mechanism contributing to light-induced lesions. Therefore, we investigated the effect of FO on acute light-induced photoreceptor damage., Methods: For 2 months, weanling rats were fed diets containing either soybean oil (SOY) or FO as main lipid component., Results: Rats fed FO had significantly higher levels of eicosapentaenoic acid (EPA, 20:5n-3) and higher ratios of EPA to arachidonic acid (AA, 20:4n-6) in retinal phospholipids and diacylglycerols than rats fed SOY. The levels of docosahexaenoic acid (DHA, 22:6n-3) were similar in both dietary groups. The susceptibility to lipid peroxidation was enhanced in the isolated retina of FO-fed rats as shown by higher levels of thiobarbituric acid reactive substances after incubation of retinal membranes with Fe2+/ascorbate. The retinal content of alpha-tocopherol was similar in SOY- and FO-fed animals. Light damage consisting of acute rod outer segment (ROS) disruptions was induced by exposing dark-adapted animals to 600 to 700 lux (230 to 260 microW/cm2) of white fluorescent light for 30 minutes. Damage was quantitated using a computerized multifunctional image analysis of retinal thin sections. Although structural alterations of the ROS were present in both groups, FO-fed rats showed less damage at the base of the ROS. This occurred in spite of higher rhodopsin levels in FO-fed rats. There was no effect of diet on retinal morphology in dark-adapted rats., Conclusion: These results indicate that FO does not enhance the susceptibility to acute ROS disk disruptions in the rat retina. Our study further suggests that FO exerts a partial protective effect that may be related to changes in the formation of lipid mediators derived from EPA and AA in retinal phospholipids.

We tested the effect of an antagonist of platelet-activating factor (PAF), BN 52021, on both acute light-induced and light plus lithium-induced rod outer segment (ROS) lesions. Rats were fed lithium carbonate (2.6 g/kg chow) for 3 weeks. Half of the lithium-treated rats received BN 52021 (25 mg/kg) via gastric intubation prior to light exposure. Control and treated rats were exposed to 400-450 lux (measured at the eye level of the rats) of diffuse, white fluorescent light for 30 min, followed by 2 h of darkness and then decapitated. The eyes were removed and prepared for light and electron microscopic observation. The structural alterations of ROS were quantified from electron micrographs using a multifunctional computer image-analysis system. Our data show a significant reduction of ROS lesions by BN 52021, and this is most pronounced in light plus lithium-treated rats. Furthermore, in confirmation of previous studies, chronic lithium treatment significantly augmented light-elicited phagosome numbers, and BN 52021 reduced this effect. Our findings thus suggest that light and lithium may act via PAF responses in the rat retina.