| 61. |
- Abbas, Abdul-Karim, 1959
(författare)
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Protein Synthesis Inhibitors Did Not Interfere with Long-Term Depression Induced either Electrically in Juvenile Rats or Chemically in Middle-Aged Rats
- 2016
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- In testing the hypothesis that long-term potentiation (LTP) maintenance depends on triggered protein synthesis, we found no effect of protein synthesis inhibitors (PSIs) on LTP stabilization. Similarly, some studies reported a lack of effect of PSIs on long-term depression (LTD); the lack of effect on LTD has been suggested to be resulting from the short time recordings. If this proposal were true, LTD might exhibit sensitivity to PSIs when the recording intervals were enough long. We firstly induced LTD by a standard protocol involving low frequency stimulation, which is suitable for eliciting NMDAR-LTD in CA1 area of hippocampal slices obtained from juvenile Sprague-Dawley rats. This LTD was persistent for intervals in range of 8-10 h. Treating slices with anisomycin, however, did not interfere with the magnitude and persistence of this form of LTD. The failure of anisomycin to block synaptic-LTD might be relied on the age of animal, the type of protein synthesis inhibitors and/or the inducing protocol. To verify whether those variables altogether were determinant, NMDA or DHPG was used to chemically elicit LTD recorded up to 10 h on hippocampal slices obtained from middle-aged rats. In either form of LTD, cycloheximide did not interfere with LTD stabilization. Furthermore, DHPG application did show an increase in the global protein synthesis as assayed by radiolabeled methodology indicating that though triggered protein synthesis can occur but not necessarily required for LTD expression. The findings confirm that stabilized LTD in either juvenile, or middle-aged rats can be independent of triggered protein synthesis. Although the processes responsible for the independence of LTD stabilization on the triggered protein synthesis are not yet defined, these findings raise the possibility that de novo protein synthesis is not universally necessary.
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| 62. |
- Abbas, Abdul-Karim, 1959
(författare)
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Re-evaluation of the hypothesis that LTP has two temporal phases and that the late phase is protein synthesis-dependent
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Long-term potentiation (LTP) is an activity-dependent increase in synaptic efficacy that is most studied in the hippocampus and that is considered a cellular substrate for learning and memory. Accepting the belief that the durability (persistence in time) of LTP is analogical to long-standing store of hippocampus-dependent memories warrants the necessity for understanding the mechanisms underlying LTP stabilization. Although the great majority of neuroscientists assume that LTP induction, akin to the formation of memories triggers the synthesis of proteins that are instrumental for subsequent consolidation neither the identity of such presumed proteins nor the mechanisms by which they act to consolidate LTP are clear. Based on this notion LTP is distinguished temporally into an early phase (E-LTP), which is protein synthesis-independent and a late phase (L-LTP), which is protein synthesis-dependent. However, several behavioral and electrophysiological findings cast doubts on this notion. In the present thesis I have examined the effect of protein synthesis inhibitors (PSIs) on the stabilization of LTP in hippocampal slices obtained from young rats. Treating hippocampal slices with PSIs using a temporal window relative to the induction of LTP that has previously been used in the literature failed to block L-LTP, a result in contrast with published data. However, long-lasting pretreatment with the PSI emetine blocked LTP by LTP-unrelated mechanism as the drug showed deteriorating effect on the baseline response. In contrast, depleting the protein repertoire in the slice by long-lasting pretreatment with the PSI cycloheximide deteriorated the stabilization of LTP. Additionally, acceleration of protein degradation using hydrogen peroxide after the induction of LTP resulted in decay of LTP. Addition of cycloheximide induced additive decay of LTP stabilization. These contradictory findings have recently been replicated by other laboratories. In this thesis I present a working model that aims to explain the discrepant findings regarding PSI and LTP. The model concedes that knowing the kinetics of protein turnover during the induction of LTP may provide a prediction for the subsequent stabilization of LTP. This can explain the wide variability in the time course of the presumed protein-synthesis independent E-LTP. The model gains support from experiments in which a low concentration of the proteasome inhibitor MG-115 improved the stability of LTP induced by a weak induction protocol. In summary, my results suggest that 1) the temporal distinction of LTP into E- and L-LTP is a false dichotomy and 2) the rate of protein degradation may explain whether PSIs would, or would not, have an effect on LTP stabilization.
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| 63. |
- Abbas, Abdul-Karim, 1959, et al.
(författare)
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Temporal phases of long-term potentiation (LTP): myth or fact?
- 2015
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Ingår i: Reviews in the Neurosciences. - : Walter de Gruyter GmbH. - 0334-1763 .- 2191-0200. ; 26:5, s. 507-546
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Tidskriftsartikel (refereegranskat)abstract
- Long-term potentiation (LTP) remains the most widely accepted model for learning and memory. In accordance with this belief, the temporal differentiation of LTP into early and late phases is accepted as reflecting the differentiation of short-term and long-term memory. Moreover, during the past 30 years, protein synthesis inhibitors have been used to separate the early, protein synthesis-independent (E-LTP) phase and the late, protein synthesis-dependent (L-LTP) phase. However, the role of these proteins has not been formally identified. Additionally, several reports failed to show an effect of protein synthesis inhibitors on LTP. In this review, a detailed analysis of extensive behavioral and electrophysiological data reveals that the presumed correspondence of LTP temporal phases to memory phases is neither experimentally nor theoretically consistent. Moreover, an overview of the time courses of E-LTP in hippocampal slices reveals a wide variability ranging from <1 h to more than 5 h. The existence of all these conflictual findings should lead to a new vision of LTP. We believe that the E-LTP vs. L-LTP distinction, established with protein synthesis inhibitor studies, reflects a false dichotomy. We suggest that the duration of LTP and its dependency on protein synthesis are related to the availability of a set of proteins at synapses and not to the de novo synthesis of plasticity-related proteins. This availability is determined by protein turnover kinetics, which is regulated by previous and ongoing electrical activities and by energy store availability. RAHAM WC, 1991, MOLECULAR NEUROBIOLOGYSATELLITE MEETING ON MOLECULAR MECHANISMS RAHAM WC, 1995, MOLECULAR BRAIN RESEARCH, V30, P367 RAHAM WC, 1993, NEUROSCIENCE, V56, P717
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| 64. |
- Abbas, Abdul-Karim, 1959
(författare)
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Testing the conditions of long-term potentiation vulnerability for enhancement and interruption in CA1 area from mice hippocampal slices
- 2015
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Ingår i: The 12th International Meeting of Society of Neuroscientists of Africa (SONA) 25-30 March 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Based on the recent findings that show that both long-term potentiation (LTP) and long-term depression (LTD) can be stabilized for several hours in hippocampal slices obtained from rat or mice, we have developed a theoretical model that explain these contradictory findings to the major literature. Our model conceded, in contrast to the prevalent dogma in the neuroscience of synaptic plasticity, that protein turnover rather than the presumed triggered protein synthesis has predictive power for the outcome of synaptic plasticity under conditions of protein synthesis inhibition (Abbas et al., Rev. Neurosci., Submitted). We predicted that when the degree of ATP perturbation produced by the LTP-inducing stimulation was not very high, either due to the type of LTP-inducing protocol (e.g. “weak”) or if the compensatory non-neuronal energy sources alleviate the state of transient ATP disturbance, the rate of activity-dependent degradation will be generally low and protein synthesis inhibitors might have no effect unless the protein synthesis inhibition interval covers the half-life of necessary proteins. To empirically verify our proposed model, we conducted experiments testing the conditions under which LTP can be vulnerable to enhancement or interruption by application of protein degradation inhibitor. Benefiting from the drug characteristics of dose-dependent selective targeting of the components of the proteasome system, S20 and S26, we treated hippocampal slices obtained from adult mice with the proteasome inhibitor MG-115. Low concentrations (10-20 µM) of the drug improved the magnitude and duration of LTP induced by weak induction protocol. However, higher concentration (50 µM) diminished the magnitude of LTP induced by either weak or strong protocol. Taken together, the findings indicate that, blocking degradation of some protein components (e.g. negative proteins) improves LTP in its magnitude and/or lifetime. Conversely, when the LTP induction is associated with an increase in turnover, blocking degradation exhibits a decaying effect on LTP stabilization in similar pattern to that achieved by protein synthesis inhibitors.
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| 65. |
- Abbas, Abdul-Karim, 1959
(författare)
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The Evidence-Based Medicine Condition: A Report on Uses and Abuses
- 2017
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Ingår i: Iraqi New Medical Journal. - 2521-7429 .- 2409-5931. ; 3:1, s. 8-16
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Tidskriftsartikel (refereegranskat)abstract
- This article is not questioning the validity or even the usefulness of evidence-based medicine (EBM) technical developments. Rather, the author is engaging with the conceptual framework within which EBM has been developed, interpreted and presented. Thus, this article explores the sociopolitical conditions that underlie characterizing EBM as paradigm and the implications of this label on practicing it in the developed as well as developing world. As medicine does not belong to pure sciences, it is believed here that the claim of paradigmatic characteristic is implanted to fulfil authoritative symbolic function rather than expressing a presumed revolutionary and radical change. This authoritative function, which enables EBM to transcend the clinical epidemiology it established on, could articulate three axes: the demise of welfare state, the postmodernist assault on the classical notions of truth and certainty, and the crisis of the medical professions. One prominent evidence that supports our proposal is the dynamicity of the movement and its capacity to “engulf” everything in its way including pseudoscience. It is noted that a major consequence of assigning EBM as paradigm is to give it a legitimized and rationalized potentiality for abuse by the profit-oriented medicalpharmaceutical complex. Another major impact is on the developing countries, which because they follow the educational and practical systems of medicine in the West, are in more positive attitude to both the drug companies and to new fashions. Beyond these issues, it is argued in the current paper that the claim of paradigm attains efficiently the control and power functions of EBM via achieving “ totalizing ” discourse creating norms for the consciousness and moral identity of the clinician. In short, it is via the paradigmatic characterization EBM engages in reasserting its hegemony in the face of a variety of challenges, and at the same time, assimilates as much as possible the sources of such challenges. It is assumed that the susceptibility of EBM for corruption will continue unless the disguising power of EBM is dismantled via humanist and medical critiques.
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| 66. |
- Abbas, Zareen, 1962, et al.
(författare)
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Activity Coefficients of Concentrated Salt Solutions: A Monte Carlo Investigation
- 2019
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Ingår i: Journal of Solution Chemistry. - : Springer Science and Business Media LLC. - 0095-9782 .- 1572-8927. ; 48:8-9, s. 1222-1243
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Tidskriftsartikel (refereegranskat)abstract
- Monte Carlo (MC) simulations were used to calculate single ion and mean ionic activity coefficients and water activity in concentrated electrolytes and at elevated temperatures. By using a concentration dependent dielectric constant, the applicability range of the MC method was extended to 3mol·L−1 or beyond, depending on the salt. The calculated activity coefficients were fitted to experimental data by adjusting only one parameter, i.e., the cation radius. Fitted ionic radii obtained by such a procedure indicate the extent of cation–anion interaction in a salt solution. For example, the fitted radii of Li+ and Na+ in LiClO3 and NaClO3 indicate that Li+ is strongly hydrated and has a weak interaction with the ClO3− ion whereas Na+ forms ion pairs and loses its hydration. The single ion activity coefficients for protons and chloride ions in HCl were calculated by MC simulations and compared with experimental values obtained by ion selective electrodes. The calculated single ion activity coefficients for protons and chloride ions are much lower and higher, respectively, than the experimental values. However, the mean activity coefficients of HCl obtained by the MC simulations, ion selective electrodes and vapor pressure measurements are in good agreement. In the case of NaCl and KCl the calculated single ion activity coefficients of Na+, K+, and Cl− are much closer to the values obtained by ion selective electrodes. The results in HCl indicate that the hydrated proton is large and includes the chloride ion within the hydration shell, i.e., the apparent size of the chloride ion is negligible.
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| 67. |
- Abbas, Zareen, 1962, et al.
(författare)
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Monte Carlo simulation of the dissociation constants of CO2 in 0 to 1 molal sodium chloride between 0 and 25 °C
- 2013
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 150:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Stoichiometric dissociation constants of the carbon dioxide system in NaCl solution between 0 and 1 mol and 0 to 25 °C were estimated by Monte Carlo (MC) simulations, and compared with Pitzer calculations and experimental measurements. The MC simulations used experimentally determined dielectric constants of water at different temperatures, and optimal agreement with the experimental data and Pitzer calculations was achieved by adjusting the ionic radii. This simple procedure resulted in effective ionic radii which were further used to simulate the activity coefficients of salt mixtures. The first and second stoichiometric dissociation constants of carbonic acid in NaCl solution (pK1⁎ and pK2⁎) were estimated from the MC-derived activity coefficients of mixed salts in NaCl. The MC results are in good agreement with the experimental data as well as with the Pitzer calculations. This study shows that Monte Carlo simulations in the temperature and ionic strength range relevant to seawater can provide pK values of the same quality as Pitzer calculations, and constitutes the first step in developing a temperature-dependent MC model for seawater. While MC calculations require greater computing resources, the number of parameters derived by fitting to thermodynamic data is substantially smaller than for Pitzer calculations.
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| 68. |
- Abbas, Zareen, 1962, et al.
(författare)
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Synthesis, characterization and particle size distribution of TiO2 colloidal nanoparticles
- 2011
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - : Elsevier BV. - 0927-7757. ; 384:1-3, s. 254-261
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles of controlled size, well defined shape, pure phase and of clean surfaces are ideal model systems to investigate surface/interfacial reactions. In this study we have explored the possibility of synthesizing TiO2 nanoparticles in the size range of 7–20 nm under well controlled experimental conditions. A simple method based on the hydrolysis of TiCl4 was used to obtain particles having surfaces free from organics. Stable dispersions of TiO2 nanoparticles of various sizes were obtained by optimizing the reaction/dialysis time and temperature. The synthesized TiO2 particles were found to be predominantly of anatase phase and narrow particle size distributions were obtained. The TiO2 particles were characterized with respect to their phase, size and shape by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Particle size distribution in a colloidal dispersion was obtained by the electrospray scanning mobility particle sizer (ES-SMPS) method and compared with an average particle size determined from dynamic light scattering (DLS). The average particle sizes obtained by the DLS and ES-SMPS methods were in good agreement, while a primary particle size of 4 nm was found in X-ray diffraction irrespective of the particle size in solution. Early stages of the nucleation process were monitored by the ES-SMPS method. These results show that small particles of 4–5 nm are initially formed and it is highly likely that large particles are formed due to aggregation of primary particles.
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| 69. |
- Abbaspoor, Zahra, et al.
(författare)
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Translation and cultural adaptation of the Childbirth Experience Questionnaire (CEQ) in Iran
- 2019
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Ingår i: Iranian Journal of Nursing and Midwifery Research. - 1735-9066 .- 2228-5504. ; 24:4, s. 296-300
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Iranian Journal of Nursing and Midwifery Research Published by Wolters Kluwer - Medknow. A standardized method to measure and quantify women's birth experiences is required to study satisfaction of childbirth care. Therefore, this study aimed to translate and culturally adapt the Childbirth Experience Questionnaire (CEQ) for use in Iran. Materials and Methods: This was a cross-sectional study including 203 women who attended 2 hospitals and 2 health centers and met the inclusion criteria in Ahvaz city, between February 2013 and June 2014. After forward and backward translation of the Swedish CEQ into Persian language, content validity was assessed by an expert panel. Scale reliability (internal consistency and test-retest reliability) was assessed with respect to the psychometric properties of the scale. Results: Minor cultural differences were identified and resolved during the translation process. One item was excluded. The intraclass correlation coefficient ranging from 0.63 to 0.90 was satisfactory. Conclusions: The Persian version of the CEQ appears to be valid and reliable; hence, it can be an effective tool in designing childbirth experience interventions and also childbirth care and education interventions for the promotion of positive childbirth experience in Iranian women.
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| 70. |
- Abbaszadehbanaeiyan, Amin, et al.
(författare)
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Design and fabrication of high-throughput application-specific microfluidic devices for studying single-cell responses to extracellular perturbations
- 2013
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Ingår i: Proc. SPIE 8765, Bio-MEMS and Medical Microdevices, 87650K. ; 8765
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Konferensbidrag (refereegranskat)abstract
- Single cell analysis techniques provide a unique opportunity of determining the intercellular heterogeneity in a cell population, which due to genotype variations and different physiological states of the cells i.e. size, shape and age, cannot be retrieved from averaged cell population values. In order to obtain high-value quantitative data from single-cell experiments it is important to have experimental platforms enabling high-throughput studies. Here, we present a microfluidic chip, which is capable of capturing individual cells in suspension inside separate traps. The device consists of three adjacent microchannels with separate inlets and outlets, laterally connected through the V-shaped traps. Vshaped traps, with openings smaller than the size of a single cell, are fabricated in the middle (main) channel perpendicular to the flow direction. Cells are guided into the wells by streamlines of the flows and are kept still at the bottom of the traps. Cells can then be exposed to extracellular stimuli either in the main or the side channels. Microchannels and traps of different sizes can be fabricated in polydimethylsiloxane (PDMS), offering the possibility of independent studies on cellular responses with different cell types and different extracellular environmental changes. We believe that this versatile high-throughput cell trapping approach will contribute to further development of the current knowledge and information acquired from single-cell studies and provide valuable statistical experimental data required for systems biology. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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