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Translating ethical and quality principles for the effective, safe and fair development, deployment and use of artificial intelligence technologies in healthcare. J Am Med Inform Assoc 2024; 31:705-713. [PMID: 38031481 PMCID: PMC10873841 DOI: 10.1093/jamia/ocad221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 10/06/2023] [Accepted: 11/03/2023] [Indexed: 12/01/2023] Open
Abstract
OBJECTIVE The complexity and rapid pace of development of algorithmic technologies pose challenges for their regulation and oversight in healthcare settings. We sought to improve our institution's approach to evaluation and governance of algorithmic technologies used in clinical care and operations by creating an Implementation Guide that standardizes evaluation criteria so that local oversight is performed in an objective fashion. MATERIALS AND METHODS Building on a framework that applies key ethical and quality principles (clinical value and safety, fairness and equity, usability and adoption, transparency and accountability, and regulatory compliance), we created concrete guidelines for evaluating algorithmic technologies at our institution. RESULTS An Implementation Guide articulates evaluation criteria used during review of algorithmic technologies and details what evidence supports the implementation of ethical and quality principles for trustworthy health AI. Application of the processes described in the Implementation Guide can lead to algorithms that are safer as well as more effective, fair, and equitable upon implementation, as illustrated through 4 examples of technologies at different phases of the algorithmic lifecycle that underwent evaluation at our academic medical center. DISCUSSION By providing clear descriptions/definitions of evaluation criteria and embedding them within standardized processes, we streamlined oversight processes and educated communities using and developing algorithmic technologies within our institution. CONCLUSIONS We developed a scalable, adaptable framework for translating principles into evaluation criteria and specific requirements that support trustworthy implementation of algorithmic technologies in patient care and healthcare operations.
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The Hidden Costs of ChatGPT: A Call for Greater Transparency. THE AMERICAN JOURNAL OF BIOETHICS : AJOB 2023; 23:47-49. [PMID: 37812094 DOI: 10.1080/15265161.2023.2250335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
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Histochemical Evidence for Nitrogen-Transfer Endosymbiosis in Non-Photosynthetic Cells of Leaves and Inflorescence Bracts of Angiosperms. BIOLOGY 2022; 11:biology11060876. [PMID: 35741397 PMCID: PMC9220352 DOI: 10.3390/biology11060876] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/15/2022] [Accepted: 06/01/2022] [Indexed: 12/13/2022]
Abstract
Simple Summary We used light and confocal microscopy to visualize bacteria in leaf and bract cells of more than 30 species in 18 families of seed plants. We detected chemical exchanges between intracellular bacteria and plant cells. We found that endophytic bacteria that show evidence of the transfer of nitrogen to plants are present in non-photosynthetic cells of leaves and bracts of diverse plant species. Nitrogen transfer from bacteria was observed in epidermal cells, various filamentous and glandular trichomes, and other non-photosynthetic cells. The most efficient of the nitrogen-transfer endosymbioses were seen to involve glandular trichomes, as seen in hops (Humulus lupulus) and hemp (Cannabis sativa). Trichome chemistry is hypothesized to function to scavenge oxygen around bacteria to facilitate nitrogen fixation. Abstract We used light and confocal microscopy to visualize bacteria in leaf and bract cells of more than 30 species in 18 families of seed plants. Through histochemical analysis, we detected hormones (including ethylene and nitric oxide), superoxide, and nitrogenous chemicals (including nitric oxide and nitrate) around bacteria within plant cells. Bacteria were observed in epidermal cells, various filamentous and glandular trichomes, and other non-photosynthetic cells. Most notably, bacteria showing nitrate formation based on histochemical staining were present in glandular trichomes of some dicots (e.g., Humulus lupulus and Cannabis sativa). Glandular trichome chemistry is hypothesized to function to scavenge oxygen around bacteria and reduce oxidative damage to intracellular bacterial cells. Experiments to assess the differential absorption of isotopic nitrogen into plants suggest the assimilation of nitrogen into actively growing tissues of plants, where bacteria are most active and carbohydrates are more available. The leaf and bract cell endosymbiosis types outlined in this paper have not been previously reported and may be important in facilitating plant growth, development, oxidative stress resistance, and nutrient absorption into plants. It is unknown whether leaf and bract cell endosymbioses are significant in increasing the nitrogen content of plants. From the experiments that we conducted, it is impossible to know whether plant trichomes evolved specifically as organs for nitrogen fixation or if, instead, trichomes are structures in which bacteria easily colonize and where some casual nitrogen transfer may occur between bacteria and plant cells. It is likely that the endosymbioses seen in leaves and bracts are less efficient than those of root nodules of legumes in similar plants. However, the presence of endosymbioses that yield nitrate in plants could confer a reduced need for soil nitrogen and constitute increased nitrogen-use efficiency, even if the actual amount of nitrogen transferred to plant cells is small. More research is needed to evaluate the importance of nitrogen transfer within leaf and bract cells of plants.
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Cross and multiple herbicide resistance in annual bluegrass (Poa annua) populations from eastern Texas golf courses. PEST MANAGEMENT SCIENCE 2021; 77:1903-1914. [PMID: 33284481 DOI: 10.1002/ps.6217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 11/27/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Annual bluegrass is a troublesome weed in managed turf systems. A survey was conducted to evaluate the prevalence of herbicide resistance in golf course populations of annual bluegrass in eastern Texas. Screenings were conducted for two photosystem II (PS II)-inhibitor herbicides [simazine preemergence (PRE), amicarbazone postemergence (POST)], two acetolactate synthase (ALS) inhibitors (foramsulfuron POST, trifloxysulfuron POST) and one microtubule assembly inhibitor (pronamide PRE/POST). RESULTS Ninety percent of the populations were found to be resistant to at least one of the tested herbicides. The TX15-14 population was >490-, 178-, 10-, 26-, 4.3- and 3.8-fold, and the TX15-27 population was >490-, 16-, 28-, 84-, 5.2- and 4.1-fold less sensitive to simazine, amicarbazone, foramsulfuron, trifloxysulfuron, pronamide POST and pronamide PRE, respectively, compared to the susceptible standard TX15-SUS. Populations resistant to pronamide POST were completely controlled by pronamide PRE at the label recommended rate. The ALS and psbA gene sequence analysis indicated the presence of target site mutations (Ser-264-Gly in the psbA gene of TX15-14 and Trp-574-Leu in the ALS gene of TX15-27). However, given the absence of any target-site mutation in the ALS gene of TX15-14, the psbA gene of TX15-27 and α-tubulin of both populations, nontarget site mechanisms of resistance are suspected. CONCLUSION This is the first case of multiple herbicide resistance in annual bluegrass populations to three herbicide modes of action. Results show the widespread occurrence of multiple herbicide resistance in golf course annual bluegrass populations in eastern Texas and emphasize the need for the development and implementation of effective resistance management practices. © 2020 Society of Chemical Industry.
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Adherence to reporting guidelines increases the number of citations: the argument for including a methodologist in the editorial process and peer-review. BMC Med Res Methodol 2019; 19:112. [PMID: 31151417 PMCID: PMC6544961 DOI: 10.1186/s12874-019-0746-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 04/29/2019] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND From 2005 to 2010, we conducted 2 randomized studies on a journal (Medicina Clínica), where we took manuscripts received for publication and randomly assigned them to either the standard editorial process or to additional processes. Both studies were based on the use of methodological reviewers and reporting guidelines (RG). Those interventions slightly improved the items reported on the Manuscript Quality Assessment Instrument (MQAI), which assesses the quality of the research report. However, masked evaluators were able to guess the allocated group in 62% (56/90) of the papers, thus presenting a risk of detection bias. In this post-hoc study, we analyse whether those interventions that were originally designed for improving the completeness of manuscript reporting may have had an effect on the number of citations, which is the measured outcome that we used. METHODS Masked to the intervention group, one of us used the Web of Science (WoS) to quantify the number of citations that the participating manuscripts received up December 2016. We calculated the mean citation ratio between intervention arms and then quantified the uncertainty of it by means of the Jackknife method, which avoids assumptions about the distribution shape. RESULTS Our study included 191 articles (99 and 92, respectively) from the two previous studies, which all together received 1336 citations. In both studies, the groups subjected to additional processes showed higher averages, standard deviations and annual rates. The intervention effect was similar in both studies, with a combined estimate of a 43% (95% CI: 3 to 98%) increase in the number of citations. CONCLUSIONS We interpret that those effects are driven mainly by introducing into the editorial process a senior methodologist to find missing RG items. Those results are promising, but not definitive due to the exploratory nature of the study and some important caveats such as: the limitations of using the number of citations as a measure of scientific impact; and the fact that our study is based on a single journal. We invite journals to perform their own studies to ascertain whether or not scientific repercussion is increased by adhering to reporting guidelines and further involving statisticians in the editorial process.
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Prevalence of Food Insecurity, Anxiety and Depression in LGBT Young Adults. J Acad Nutr Diet 2018. [DOI: 10.1016/j.jand.2018.08.146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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14 2017 Southeast Women’s Cattle Handling Program: Alabama Results. J Anim Sci 2018. [DOI: 10.1093/jas/sky027.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Response by Madder et al to Letter Regarding Article, "Multimodality Intracoronary Imaging With Near-Infrared Spectroscopy and Intravascular Ultrasound in Asymptomatic Individuals With High Calcium Scores". Circ Cardiovasc Imaging 2018; 11:e007405. [PMID: 29305354 DOI: 10.1161/circimaging.117.007405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Radiation Exposure Among Scrub Technologists and Nurse Circulators During Cardiac Catheterization: The Impact of Accessory Lead Shields. JACC Cardiovasc Interv 2017; 11:206-212. [PMID: 29102573 DOI: 10.1016/j.jcin.2017.07.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/08/2017] [Accepted: 07/09/2017] [Indexed: 11/30/2022]
Abstract
OBJECTIVES This study was performed to determine if the use of an accessory lead shield is associated with a reduction in radiation exposure among staff members during cardiac catheterization. BACKGROUND Accessory lead shields that protect physicians from scatter radiation are standard in many catheterization laboratories, yet similar shielding for staff members is not commonplace. METHODS Real-time radiation exposure data were prospectively collected among nurses and technologists during 764 consecutive catheterizations. The study had 2 phases: in phase I (n = 401), standard radiation protection measures were used, and in phase II (n = 363), standard radiation protection measures were combined with an accessory lead shield placed between the staff member and patient. Radiation exposure was reported as the effective dose normalized to dose-area product (EDAP). RESULTS Use of an accessory lead shield in phase II was associated with a 62.5% lower EDAP per case among technologists (phase I: 2.4 [4.3] μSv/[mGy × cm2] × 10-5; phase II: 0.9 [2.8] μSv/[mGy × cm2] × 10-5; p < 0.001) and a 63.6% lower EDAP per case among nurses (phase I: 1.1 [3.1] μSv/[mGy × cm2] × 10-5; phase II: 0.4 [1.8] μSv/[mGy × cm2] × 10-5; p < 0.001). By multivariate analysis, accessory shielding remained independently associated with a lower EDAP among both technologists (34.2% reduction; 95% confidence interval: 20.1% to 45.8%; p < 0.001) and nurses (36.4% reduction; 95% confidence interval: 19.7% to 49.6%; p < 0.001). CONCLUSIONS The relatively simple approach of using accessory lead shields to protect staff members during cardiac catheterization was associated with a nearly two-thirds reduction in radiation exposure among nurses and technologists.
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Multimodality Intracoronary Imaging With Near-Infrared Spectroscopy and Intravascular Ultrasound in Asymptomatic Individuals With High Calcium Scores. Circ Cardiovasc Imaging 2017; 10:CIRCIMAGING.117.006282. [PMID: 28982647 DOI: 10.1161/circimaging.117.006282] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 08/16/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND This study sought to determine the frequency of large lipid-rich plaques (LRP) in the coronary arteries of individuals with high coronary artery calcium scores (CACS) and to determine whether the CACS correlates with coronary lipid burden. METHODS AND RESULTS Combined near-infrared spectroscopy and intravascular ultrasound was performed in 57 vessels in 20 asymptomatic individuals (90% on statins) with no prior history of coronary artery disease who had a screening CACS ≥300 Agatston units. Among 268 10-mm coronary segments, near-infrared spectroscopy images were analyzed for LRP, defined as a bright yellow block on the near-infrared spectroscopy block chemogram. Lipid burden was assessed as the lipid core burden index (LCBI), and large LRP were defined as a maximum LCBI in 4 mm ≥400. Vessel plaque volume was measured by quantitative intravascular ultrasound. Vessel-level CACS significantly correlated with plaque volume by intravascular ultrasound (r=0.69; P<0.0001) but not with LCBI by near-infrared spectroscopy (r=0.24; P=0.07). Despite a high CACS, no LRP was detected in 8 (40.0%) subjects. Large LRP having a maximum LCBI in 4 mm ≥400 were infrequent, found in only 5 (25.0%) of 20 subjects and in only 5 (1.9%) of 268 10-mm coronary segments analyzed. CONCLUSIONS Among individuals with a CACS ≥300 Agatston units mostly on statins, CACS correlated with total plaque volume but not LCBI. This observation may have implications on coronary risk among individuals with a high CACS considering that it is coronary LRP, rather than calcification, that underlies the majority of acute coronary events.
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Impact of robotics and a suspended lead suit on physician radiation exposure during percutaneous coronary intervention. CARDIOVASCULAR REVASCULARIZATION MEDICINE 2017; 18:190-196. [DOI: 10.1016/j.carrev.2016.12.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/09/2016] [Accepted: 12/14/2016] [Indexed: 10/20/2022]
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RADIATION EXPOSURE AMONG NON-PHYSICIAN STAFF MEMBERS DURING CARDIAC CATHETERIZATION AND THE IMPACT OF PROACTIVE SHIELDING. J Am Coll Cardiol 2017. [DOI: 10.1016/s0735-1097(17)35886-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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CRT-100.96 Independent Predictors of Reduced Cranial Radiation Exposure Among Physicians Performing Percutaneous Coronary Intervention. JACC Cardiovasc Interv 2017. [DOI: 10.1016/j.jcin.2016.12.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Percutaneous coronary intervention using a combination of robotics and telecommunications by an operator in a separate physical location from the patient: an early exploration into the feasibility of telestenting (the REMOTE-PCI study). EUROINTERVENTION 2017; 12:1569-1576. [DOI: 10.4244/eij-d-16-00363] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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The Influence of Tumor Location on Cosmesis and Toxicity After Interstitial Brachytherapy Accelerated Partial Breast Irradiation. Int J Radiat Oncol Biol Phys 2016. [DOI: 10.1016/j.ijrobp.2016.06.741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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CRT-600.07 Combined Near-Infrared Spectroscopy and Intravascular Ultrasound Findings in Pre-existing Coronary Stents are Associated With Subsequent Stent Failure. JACC Cardiovasc Interv 2016. [DOI: 10.1016/j.jcin.2015.12.186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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TCT-108 Initial Clinical Experience Performing Robotic Percutaneous Coronary Intervention from the Radial Approach. J Am Coll Cardiol 2015. [DOI: 10.1016/j.jacc.2015.08.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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TCT-356 Characterizing Non-culprit Coronary Artery Plaques Using Hybrid Near-infrared Spectroscopy and Intravascular Ultrasound: The Rarity of Non-culprit Lesions Having Both a Large Plaque Burden and Large Lipid Burden. J Am Coll Cardiol 2015. [DOI: 10.1016/j.jacc.2015.08.974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Cloning, expression and evaluation of a recombinant sub-unit vaccine against Clostridium botulinum type F toxin. Vaccine 2000; 19:288-97. [PMID: 10930684 DOI: 10.1016/s0264-410x(00)00155-9] [Citation(s) in RCA: 28] [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
A synthetic gene encoding the Hc (binding) domain of Clostridium botulinum neurotoxin F (FHc) was expressed in Escherichia coli fused to maltose binding protein (MBP). The purified MBP-FHc and FHc isolated after removal of MBP were evaluated in mice for their ability to protect against toxin challenge. Balb/c mice developed a protective immune response following administration of either protein via the intraperitoneal or intramuscular routes. A comparison of antibody titres and protection following single and multiple vaccinations and the effects of dosage are shown. The long term protection afforded by the vaccines was also investigated. Ten months following vaccination mice were still protected when challenged with 10(4) MLD(50) doses of botulinum toxin F.
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Abstract
BACKGROUND Thoughts of harming the infant and other disturbing cognitions are frequently described in anecdotal reports on postpartum depression. These cognitions have not been examined empirically. METHODS 100 clinically depressed mothers with a child under 3 years were evaluated and compared to a control group of 46 nondepressed mothers. RESULTS 41% of depressed mothers compared to 7% of control mothers admitted to thoughts of harming their infant. Fear of being alone with the infant and inability to care for the infant were assessed only in depressed mothers and occurred less frequently. More than half of depressed mothers had problems in one of these three areas. CONCLUSIONS Thoughts of harming the infant are common in depressed mothers. Demographic variables, psychosocial stressors and psychiatric variables do not help predict which mothers are likely to experience thoughts of harm or fear of being alone with the infant. These cognitive and affective disturbances may be one pathway by which maternal depression affects infants. LIMITATIONS The control group was not given the full diagnostic interview. Consequently, the groups were not selected by identical procedures. Also fear of being alone with the infant and difficulty caring for the infant were not assessed in the control group.
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Abstract
The SNRPN gene is known to be expressed exclusively from the paternal allele and to map to the critical region for the neurobehavioral disorder, Prader-Willi syndrome (PWS). As a means to investigate the mechanism of imprinting for the SNRPN gene, we have sought to recapitulate the imprinted expression of the endogenous gene. Using an 85-kb murine Snrpn clone, containing 33 kb of 5' and 30 kb of 3' flanking DNA, we obtained two intact transgenic lines. One line, containing two copies of the Snrpn transgene, recapitulated the imprinted expression pattern of the endogenous locus, whereas the other transgenic line, containing a single copy, was expressed upon both maternal and paternal inheritance. This suggests that a 6.6-kb region of maternal-specific DNA methylation that we have identified may be sufficient to confer imprinted expression, but not in a copy-number independent manner. Finally, we produced five lines of transgenic mice using a 76-kb human SNRPN clone containing 45 kb and 7 kb of 5' and 3' flanking DNA, respectively. We found all the lines were expressed upon both maternal and paternal inheritance, regardless of copy number, suggesting that the imprinting machinery in mouse and human may have diverged.
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Mechanism of inhibition of protein kinase C by 14-3-3 isoforms. 14-3-3 isoforms do not have phospholipase A2 activity. Biochem J 1994; 299 ( Pt 3):853-61. [PMID: 8192676 PMCID: PMC1138099 DOI: 10.1042/bj2990853] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The ability of individual members of the 14-3-3 protein family to inhibit protein kinase C (PKC) has been studied by using a synthetic peptide based on the specific 80 kDa substrate for PKC (MARCKS protein) in two different assay systems. Recombinant 14-3-3 and isoforms renatured by a novel method after separation by reverse-phase h.p.l.c. were studied. The detailed effects of diacylglycerol and the phorbol ester phorbol 12-myristate 13-acetate on the inhibition were also investigated. This suggests that one of the sites of interaction of 14-3-3 may be the cysteine-rich (C1) domain in PKC. Since a region in secreted phospholipase A2 (PLA2) shares similarity with this domain, the ability of 14-3-3 to interact with mammalian PLA2 was studied. Cytosolic PLA2 has some similarity to the C2 region of PKC, and the effect of 14-3-3 on this class of PLA2 was also analysed. In contrast with a previous report, no PLA2 activity was found in brain 14-3-3, nor in any of the recombinant proteins tested. These include zeta 14-3-3 isoform, on which the original observation was made.
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Comparison of the role of protein kinase C in platelet functional responses induced by three different mechanisms, PAF, ionomycin and arachidonic acid. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1133:46-54. [PMID: 1661165 DOI: 10.1016/0167-4889(91)90240-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The role of protein kinase C (PKC) in modulating platelet activation has been examined in platelets pre-incubated with either the PKC activator 12-O-tetradecanoylphorbol 13-acetate (TPA) or the non-specific protein kinase inhibitor, staurosporine. In order to determine where in the signal transduction pathway PKC is exerting its effect platelets were activated either with a receptor-operated stimulus platelet activating factor (PAF) or by direct elevation of [Ca2+]i (ionomycin) or with arachidonic acid which is converted into thromboxane B2 (TxB2). In PAF-stimulated platelets activation of PKC inhibited both [Ca2+]i elevation and TxB2 generation but had no effect on 5-hydroxytryptamine (5-HT) release whilst staurosporine increased the duration of [Ca2+]i elevation and potentiated TxB2 generation but inhibited 5-HT release. In ionomycin-stimulated platelets modulation of PKC had no effect on [Ca2+]i elevation but in contrast to PAF-stimulated platelets PKC activation caused potentiation of TxB2 generation and 5-HT release whilst inhibition of PKC caused inhibition of TxB2 generation and 5-HT release. Modulation of PKC did not affect arachidonic acid-induced TxB2 generation. These findings suggest that in receptor activated platelets endogenously activated PKC is exerting a negative feedback role, however, when [Ca2+]i elevation is not modified by PKC activation or inhibition (such as in ionomycin stimulated platelets) the relationship between the state of PKC activation and subsequent platelet functional responses corresponds more closely. The findings from this study suggest a different relationship between PKC and TxB2 generation than between PKC and dense granule release in PAF-stimulated platelets.
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The relationship between cytosolic Ca2+, sn-1,2-diacylglycerol and inositol 1,4,5-trisphosphate elevation in platelet-activating-factor-stimulated rabbit platelets. Influence of protein kinase C on production of signal molecules. Biochem J 1991; 278 ( Pt 1):255-61. [PMID: 1883334 PMCID: PMC1151476 DOI: 10.1042/bj2780255] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The temporal and dose-response relationships of platelet-activating-factor (PAF)-induced changes in the concentrations of cytosolic Ca2+ ([Ca2+]i), Ins(1,4,5)P3 and 1,2-diacylglycerol (DAG) were examined. In addition, phosphorylation of protein kinase C (PKC) substrate (40-47 kDa protein) was determined. In high-dose PAF-activated platelets, all three signal molecules increased rapidly and transiently, with the peak Ins(1,4,5)P3 concentration preceding maximal elevation of [Ca2+]i by 5 s. In low-dose PAF-activated platelets there were large increases in [Ca2+]i and dense-granule release, without any increase in Ins(1,4,5)P3 and DAG or 40-47 kDa protein phosphorylation. Staurosporine, a non-specific PKC inhibitor, produced enhanced elevations in the concentrations of Ins(1,4,5)P3, DAG and thromboxane B2, and the duration of the Ca2+ signal in platelets stimulated with a high dose, but not a low dose, of PAF. These results suggest there are both phospholipase C-dependent and -independent changes in Ca2+ homoeostasis. Endogenously activated PKC regulates the formation of signal molecules.
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Thyroliberin and luliberin degradation by enzymes in cultured cells of neural origin. Biochem Soc Trans 1991; 19:36S. [PMID: 1674702 DOI: 10.1042/bst019036s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Degradation of thyrotropin-releasing hormone and luteinising hormone-releasing hormone by enzymes of brain tissue. J Neurochem 1990; 54:1-13. [PMID: 2104543 DOI: 10.1111/j.1471-4159.1990.tb13276.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this article, the enzymes of brain and associated tissues that can degrade thyrotropin-releasing hormone (TRH) and luteinising hormone-releasing hormone (LH-RH) are reviewed. As both TRH and LH-RH are considered to act as neurotransmitters or neuromodulators in the CNS, attention is paid to the subcellular location of the enzymes described and how their topographies and substrate specificities fit them to playing roles as inactivating agents for TRH and LH-RH or as regulators of intracellular concentrations of TRH and LH-RH. Consideration is also given to enzymes involved in biotransformation of TRH to secondary metabolites that exhibit biological activity and to enzymes involved in the metabolism of secondary metabolites.
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Comparison of radially sensitive and circumferentially sensitive microtransducer esophageal manometry probes in normal subjects. Am J Gastroenterol 1988; 83:151-4. [PMID: 3341337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Circumferentially sensitive microtransducer probes are commercially available for use in esophageal manometry, and may offer an advantage over radially sensitive microtransducer probes in sphincters with radial asymmetry. In order to compare performance of the two probes, we performed esophageal manometry in 30 healthy adult volunteers with both probes. In only three of 52 manometric parameters measured were differences between mean values for the two probes statistically significant. Intrasubject variability was significantly (p = less than 0.005) less with the circumferentially sensitive probe (coefficient of variation 37% vs. 53%).
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Abstract
Enteroclysis is an examination in which barium is infused directly into the small intestine, and compression radiographs are taken on each segment. This method eliminates many of the inherent limitations of the conventional small bowel follow-through examination. This report concerns 45 patients with 48 small bowel lesions. They were missed on the conventional examination but detected within 3 months by subsequent enteroclysis and confirmed surgically. There were 15 patients with Meckel's diverticula, 7 with obstructive adhesive bands, 5 with Crohn's disease, 5 with blind pouch syndrome (1 with a leiomyoma inside the blind pouch), 2 with other leiomyomas, 3 with metastatic carcinoma, two with primary carcinoma 3 with radiation stricture, two with sinus tract lesions and fistulas, and 1 with another lesion. Improved intubation techniques and better barium mixtures make enteroclysis possible in most hospitals. As surgeons appreciate the value of enteroclysis, they can request this examination for appropriate patients to sooner find many surgical lesions of the small bowel which frequently go undiagnosed.
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Abstract
With the flexible fiberoptic esophagogastroduodenoscopes now in use, the larynx and posterior pharynx can be easily viewed during routine upper gastrointestinal endoscopy. Screening laryngeal-pharyngeal examinations were carried out during 1120 upper gastrointestinal endoscopies. Mean additional examination time was 30 sec. Thirty-nine laryngeal lesions were detected, mostly variants of chronic laryngitis. Two patients had leukoplakia, one of whom on subsequent biopsy revealed squamous cell cancer. The brief additional endoscopic time may result in the detection of early curable neoplasms. Thus a screening laryngeal-pharyngeal examination should be part of each upper gastrointestinal endoscopic examination.
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Congenital concurrence of adrenal cortical tumor, ganglioneuroma, and toxoplasmosis. Pediatrics 1973; 51:705-9. [PMID: 4697518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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