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Search Results: 1 - 10 of 118507 matches for " Edmund T Nartey "
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Antioxidant and gastric cytoprotective prostaglandins properties of Cassia sieberiana roots bark extract as an anti-ulcerogenic agent
Edmund T Nartey, Mark Ofosuhene, William Kudzi, Caleb M Agbale
BMC Complementary and Alternative Medicine , 2012, DOI: 10.1186/1472-6882-12-65
Abstract: Antioxidant and radical scavenging activities of the roots bark extract of Cassia sieberiana were assayed. Serum secretory phospholipase A2 (sPLA2) concentration and activity and the formation of gastric mucosal prostaglandins E2 (PGE2) and I2 (PGI2) were also assessed. Comparisons between means were performed using analysis of variance (ANOVA) followed by Students Standard Newman-Keuls post hoc analysis to determine statistical significance. P?<?0.05 was considered significant.The extract was found to possess significant ferric reducing antioxidant power and can scavenge hydroxyl radicals. The extract also possesses DPPH scavenging activity, can chelate ferrous ion and a dose-dependent protective effect against lipid peroxidation and free radical generation. Prostaglandin studies showed that the roots bark extract dose dependently increased gastric mucosal PGE2 and PGI2 levels and also decreased serum sPLA2 activity. Phytochemical analyses suggest that the roots extract contains polyhydroxyl/phenolic substances. Acute toxicity test showed no sign of toxicity up to a dose level of 2000?mg/kg body weight p.o.C. sieberiana roots extract possesses significant antioxidant and gastric cytoprotective prostaglandin properties as well as serum secretory phospholipase A2 inhibitory activity which could be due to its content of polyhydroxy and/or phenolic substances. This may justify its use as an anti-ulcerogenic agent in traditional medicine in West Africa.
Anti-ulcerogenic activity of the root bark extract of the African laburnum “Cassia sieberiana” and its effect on the anti-oxidant defence system in rats
Nartey Edmund T,Ofosuhene Mark,Agbale Caleb M
BMC Complementary and Alternative Medicine , 2012, DOI: 10.1186/1472-6882-12-247
Abstract: Background Despite the widespread use of roots of Cassia sieberiana in managing several health conditions including gastric ulcer disease, there is little scientific data to support the rational phytotherapeutics as an anti-ulcer agent. This paper reports an evaluation of the in vivo anti-oxidant properties of an aqueous root bark extract of C. sieberiana in experimental gastric ulcer rats in a bid to elucidate its mechanism of action. Methods Fisher 344 (F344) rats received pretreatment of C. sieberiana root bark extract (500, 750, and 1000 mg/kg body wt.) for 7 days after which there was induction of gastric injury with absolute ethanol. The mean ulcer index (MUI) was calculated and serum total anti-oxidant level determined. Gastric mucosal tissues were prepared and the activity level of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and myeloperoxidase (MPO) were measured together with the level of lipid hydroperoxides (LPO). Statistical difference between treatment groups was analysed using one-way analysis of variance (ANOVA) followed by Dunnett’s post hoc t test. Statistical significance was calculated at P< 0.05. Results The administration of ethanol triggered severe acute gastric ulcer and pretreatment with C. sieberiana root bark extract significantly and dose dependently protected against this effect. The root bark extract also dose dependently and significantly inhibited the ethanol induced decrease in activity levels of the enzymes SOD, CAT and GPx. The extract also inhibited the ethanol-induced decrease in level of serum total anti-oxidant capacity. The increase in ethanol-induced LPO level and MPO activity were also significantly and dose-dependently inhibited by the root bark extract. Conclusions The gastro-cytoprotective effect, inhibition of decrease in activity of gastric anti-oxidant enzymes and MPO as well as the inhibition of gastric LPO level suggests that one of the anti-ulcer mechanisms of C. sieberiana is the anti-oxidant property.
Unexpected elevated alanine aminotransferase, asparte aminotransferase levels and hepatitis E virus infection among persons who work with pigs in accra, ghana
Andrew A Adjei, Yao Tettey, John T Aviyase, Clement Adu-Gyamfi, Julius A Mingle, Edmund T Nartey
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-336
Abstract: Three hundred and fifty- persons who work with pigs provided blood samples for unlinked anonymous testing for the presence of antibodies to HEV, ALT and AST levels. The median age of participants was 32.85 ± 11.38 years (range 15-70 years). HEV seroprevelance was 34.84%. Anti-HEV IgG was detected in 19.26% while anti-HEV IgM was detected in 15.58% of the persons who tested positive. On multivariate analysis, the independent determinants of HEV infection were, being employed on the farm for less than six months [odds ratio (OR) 8.96; 95% confidence interval (95% CI) 5.43-14.80], having piped water in the household and/or on the farm (OR 13.33; 95% CI 5.23-33.93) and consumption of alcohol (OR 4.91: 95% CI 2.65-9.10). Levels >3× the expected maximum were found for both ALT and AST among individuals who tested positive for anti-HEV IgG (ALT, 210.17 ± 11.64 U/L; AST, 127.18 ± 11.12 U/L) and anti-HEV IgM (ALT, 200.97 ± 10.76 U/L; AST, 120.00 ± 15.96 U/L).Consistent with similar studies worldwide, the results of our studies revealed a high prevalence of HEV infection, ALT and AST values in pig handlers.Hepatitis E virus (HEV) infection is one of the major cause of human viral disease with clinical and pathological features of acute hepatitis. The infection represents an important public health concern in many developing countries, where it is primarily transmitted through the faecal oral route due to contaminated water and food [1], and is often responsible for epidemic outbreaks [2]. The infection affects primarily young adults and is generally mild, except for women in late pregnancy in whom 20% mortality has been reported [3].The first animal strain of HEV was characterised in pigs in the United States of America [4,5] and since then several other strains have been described in pigs worldwide [4,6] suggestive that pigs can represent a reservoir of the infection. The identification of a U.S.A. strain of HEV apparently acquired inside the U.S.A. after the isolation of a
Pattern of drug utilization for treatment of uncomplicated malaria in urban Ghana following national treatment policy change to artemisinin-combination therapy
Alexander NO Dodoo, Carole Fogg, Alex Asiimwe, Edmund T Nartey, Augustina Kodua, Ofori Tenkorang, David Ofori-Adjei
Malaria Journal , 2009, DOI: 10.1186/1475-2875-8-2
Abstract: Patients with diagnosis of uncomplicated malaria were recruited from pharmacies of health facilities throughout Accra in a cohort-event monitoring study. The main drug utilization outcomes were the relation of patient age, gender, type of facility attended, mode of diagnosis and concomitant treatments to the anti-malarial regimen prescribed. Logistic regression was used to predict prescription of nationally recommended first-line therapy and concomitant prescription of antibiotics.The cohort comprised 2,831 patients. Curative regimens containing an artemisinin derivative were given to 90.8% (n = 2,574) of patients, although 33% (n = 936) of patients received an artemisinin-based monotherapy. Predictors of first-line therapy were laboratory-confirmed diagnosis, age >5 years, and attending a government facility. Analgesics and antibiotics were the most commonly prescribed concomitant medications, with a median of two co-prescriptions per patient (range 1–9). Patients above 12 years were significantly less likely to have antibiotics co-prescribed than patients under five years; those prescribed non-artemisinin monotherapies were more likely to receive antibiotics. A dihydroartemisinin-amodiaquine combination was the most used therapy for children under five years of age (29.0%, n = 177).This study shows that though first-line therapy recommendations may change, clinical practice may still be affected by factors other than the decision or ability to diagnose malaria. Age, diagnostic confirmation and suspected concurrent conditions lead to benefit:risk assessments for individual patients by clinicians as to which anti-malarial treatment to prescribe. This has implications for adherence to policy changes aiming to implement effective use of ACT. These results should inform education of health professionals and rational drug use policies to reduce poly-pharmacy, and also suggest a potential positive impact of increased access to testing for malaria both within health facil
Invariant Visual Object and Face Recognition: Neural and Computational Bases, and a Model, VisNet
Edmund T. Rolls
Frontiers in Computational Neuroscience , 2012, DOI: 10.3389/fncom.2012.00035
Abstract: Neurophysiological evidence for invariant representations of objects and faces in the primate inferior temporal visual cortex is described. Then a computational approach to how invariant representations are formed in the brain is described that builds on the neurophysiology. A feature hierarchy model in which invariant representations can be built by self-organizing learning based on the temporal and spatial statistics of the visual input produced by objects as they transform in the world is described. VisNet can use temporal continuity in an associative synaptic learning rule with a short-term memory trace, and/or it can use spatial continuity in continuous spatial transformation learning which does not require a temporal trace. The model of visual processing in the ventral cortical stream can build representations of objects that are invariant with respect to translation, view, size, and also lighting. The model has been extended to provide an account of invariant representations in the dorsal visual system of the global motion produced by objects such as looming, rotation, and object-based movement. The model has been extended to incorporate top-down feedback connections to model the control of attention by biased competition in, for example, spatial and object search tasks. The approach has also been extended to account for how the visual system can select single objects in complex visual scenes, and how multiple objects can be represented in a scene. The approach has also been extended to provide, with an additional layer, for the development of representations of spatial scenes of the type found in the hippocampus.
A quantitative theory of the functions of the hippocampal CA3 network in memory
Edmund T. Rolls
Frontiers in Cellular Neuroscience , 2013, DOI: 10.3389/fncel.2013.00098
Abstract: A quantitative computational theory of the operation of the hippocampal CA3 system as an autoassociation or attractor network used in episodic memory system is described. In this theory, the CA3 system operates as a single attractor or autoassociation network to enable rapid, one-trial, associations between any spatial location (place in rodents, or spatial view in primates) and an object or reward, and to provide for completion of the whole memory during recall from any part. The theory is extended to associations between time and object or reward to implement temporal order memory, also important in episodic memory. The dentate gyrus (DG) performs pattern separation by competitive learning to produce sparse representations suitable for setting up new representations in CA3 during learning, producing for example neurons with place-like fields from entorhinal cortex grid cells. The dentate granule cells produce by the very small number of mossy fiber (MF) connections to CA3 a randomizing pattern separation effect important during learning but not recall that separates out the patterns represented by CA3 firing to be very different from each other, which is optimal for an unstructured episodic memory system in which each memory must be kept distinct from other memories. The direct perforant path (pp) input to CA3 is quantitatively appropriate to provide the cue for recall in CA3, but not for learning. Tests of the theory including hippocampal subregion analyses and hippocampal NMDA receptor knockouts are described, and support the theory.
The mechanisms for pattern completion and pattern separation in the hippocampus
Edmund T. Rolls
Frontiers in Systems Neuroscience , 2013, DOI: 10.3389/fnsys.2013.00074
Abstract: The mechanisms for pattern completion and pattern separation are described in the context of a theory of hippocampal function in which the hippocampal CA3 system operates as a single attractor or autoassociation network to enable rapid, one-trial, associations between any spatial location (place in rodents, or spatial view in primates) and an object or reward, and to provide for completion of the whole memory during recall from any part. The factors important in the pattern completion in CA3 together with a large number of independent memories stored in CA3 include a sparse distributed representation which is enhanced by the graded firing rates of CA3 neurons, representations that are independent due to the randomizing effect of the mossy fibers, heterosynaptic long-term depression as well as long-term potentiation in the recurrent collateral synapses, and diluted connectivity to minimize the number of multiple synapses between any pair of CA3 neurons which otherwise distort the basins of attraction. Recall of information from CA3 is implemented by the entorhinal cortex perforant path synapses to CA3 cells, which in acting as a pattern associator allow some pattern generalization. Pattern separation is performed in the dentate granule cells using competitive learning to convert grid-like entorhinal cortex firing to place-like fields. Pattern separation in CA3, which is important for completion of any one of the stored patterns from a fragment, is provided for by the randomizing effect of the mossy fiber synapses to which neurogenesis may contribute, by the large number of dentate granule cells each with a sparse representation, and by the sparse independent representations in CA3. Recall to the neocortex is achieved by a reverse hierarchical series of pattern association networks implemented by the hippocampo-cortical backprojections, each one of which performs some pattern generalization, to retrieve a complete pattern of cortical firing in higher-order cortical areas.
Chemosensory Learning in the Cortex
Edmund T. Rolls
Frontiers in Systems Neuroscience , 2011, DOI: 10.3389/fnsys.2011.00078
Abstract: Taste is a primary reinforcer. Olfactory–taste and visual–taste association learning takes place in the primate including human orbitofrontal cortex to build representations of flavor. Rapid reversal of this learning can occur using a rule-based learning system that can be reset when an expected taste or flavor reward is not obtained, that is by negative reward prediction error, to which a population of neurons in the orbitofrontal cortex responds. The representation in the orbitofrontal cortex but not the primary taste or olfactory cortex is of the reward value of the visual/olfactory/taste input as shown by devaluation experiments in which food is fed to satiety, and by correlations of the activations with subjective pleasantness ratings in humans. Sensory-specific satiety for taste, olfactory, visual, and oral somatosensory inputs produced by feeding a particular food to satiety is implemented it is proposed by medium-term synaptic adaptation in the orbitofrontal cortex. Cognitive factors, including word-level descriptions, modulate the representation of the reward value of food in the orbitofrontal cortex, and this effect is learned it is proposed by associative modification of top-down synapses onto neurons activated by bottom-up taste and olfactory inputs when both are active in the orbitofrontal cortex. A similar associative synaptic learning process is proposed to be part of the mechanism for the top-down attentional control to the reward value vs. the sensory properties such as intensity of taste and olfactory inputs in the orbitofrontal cortex, as part of a biased activation theory of selective attention.
Knowledge and Perception of Malaria Rapid Diagnostic Test among Medical Doctors in a South Eastern Nigeria Tertiary Hospital  [PDF]
Edmund O. Ndibuagu, Ogechukwu F. Amadi, Ejiofor T. Ugwu
Journal of Biosciences and Medicines (JBM) , 2017, DOI: 10.4236/jbm.2017.510001
Abstract: Malaria commonly causes fever in tropical Africa. In 2010, World Health Organization recommended parasitological diagnosis of malaria before treatment. Rapid Diagnostic Test (RDT) aims at making malaria diagnosis more accessible. The objective of this study was to assess knowledge, and perception of malaria rapid diagnostic test (mRDT), among doctors in a tertiary health facility. A descriptive, cross sectional study, conducted in October 2016, in a state University Teaching hospital, Enugu state, Nigeria. 86 doctors in the General Outpatient, Internal Medicine, and Paediatrics departments participated. 90.7% of respondents knew parasitological examination of blood is the certain method of making malaria diagnosis, 89.5% knew microscopy and RDT are methods for parasitological diagnosis, 91.9% knew mRDT is quick blood test for malaria, 54.7% knew mRDT is usually specific for one or more species of malaria, 46.5% knew mRDT detects circulating malaria parasite antigen, 29.1% knew mRDT is read 15 to 20 minutes after the test, 70.9% knew mRDT is not superior to microscopy, 79.1% knew mRDT is not 100% specific, 80.2% knew mRDT ought not be done always by Laboratory Scientists, and 66.3% knew more than one type of mRDT kit is available. On perception, 64.0% thought it was important to confirm diagnosis before commencing treatment, 90.7% perceived mRDT as being very useful, 96.5% did not perceive mRDT as endangering patients, 70.9% opinioned that presumptive diagnosis of malaria is not a better way of making diagnosis, 76.7% did not believe malaria diagnosis is always clear on listening to the patient, 90.7% did not perceive mRDT as being hazardous, 83.7% believe using mRDT can reduce the quantity of anti-malaria drugs consumed, and 94.2% opinioned that mRDT should be encouraged and promoted. Training and re-training of health workers shall greatly enhance mRDT use in implementing the WHO T3 Initiative, and ultimately eliminating malaria.
Mercury Pollution Studies of Some Rivers Draining the Bibiani-Anwiaso-Bekwai Mining Community of South Western Ghana
V.K. Nartey,L.K. Doamekpor,S. Sarpong-Kumankuma,T. Akabzaa
Research Journal of Environmental and Earth Sciences , 2011,
Abstract: The project assessed the extent of mercury pollution of some rivers that drain the Bibiani-Anwiaso- Bekwai district which is a typical mining community in the south western part of Ghana. In the study, surfacewater and sediment samples were collected from seven streams that drain this mining community and analyzed for total mercury, organic mercury and elemental mercury. Mercury concentrations of non-filtered water was determined using the ICP-OES after reduction with stannous chloride (SnCl2). Physico-chemical parameters were also determined for the water samples. Sediment samples were pretreated and their mercury content determined using the same instrumental technique as for the water. Total mercury content of the water ranged between 0.125 to 1.341 μg/L while sediment values ranged between 0.169 to 1.739 mg/kg. In all cases except for one site, mercury levels in the sediment have been found to be significantly higher than the corresponding water column. Except for site SW7 (1.341 μg/L), total mercury in water has also been found to be lower than 1.0 μg/L, the WHO guideline value for drinking water. On the contrary, except for site ASUS (169 mg/kg), all sampled sediments recorded values that were above 0.2 mg/kg, the US-EPA guideline value for soils. Since sediments serve as sink for mercury and release the metal into water column with time, it can be concluded that these streams are polluted with mercury.
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