Search results for: cerebral perfusion
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 280

Search results for: cerebral perfusion

130 Post Coronary Artery Stenting Reflighting: Need for Change in Policy with Changing Antiplatelet Therapy

Authors: Keshavamurthy Ganapathy Bhat, Manvinderpal Singh Marwaha

Abstract:

Background: Coronary artery Disease (CAD) is a common cause of morbidity, mortality and reason for unfitness amongst aircrew. Coronary angioplasty and stenting are the standard of care for CAD. Antiplatelet drugs like Aspirin and Clopidogrel(Dual Antiplatelet therapy) are routinely prescribed post-stenting which are permitted for flying. However, in the recent past, Ticagrelor is being used in place of Clopidogrel as per ACC AHA and ESC guidelines. However Ticagrelor is not permitted for flying. Case Presentation: A 55-year-old pilot suffered Anterior Wall Myocardial Infarction. Angiography showed blockages in Left Anterior Descending Artery(LAD) and Right coronary artery (RCA). He underwent primary angioplasty and stenting LAD and subsequent stenting to RCA. Recovery was uneventful. One year later he was asymptomatic with normal Left ventricular function and no reversible perfusion defect on stress MPI. He had patent stents and coronaries on check angiogram. However, he was not allowed to fly since he was on Ticagrelor. He had to be switched over to Clopidogrel from Ticagrelor one year after stenting to permit him for flying. Similarly, switching had to be done in a 45-year-old pilot. Ticagrelor has been proven to be more effective than clopidogrel and as safe as Clopidogrel in preventing stent thrombosis. If Clopidogrel is being permitted, there is no need to restrict Ticagrelor. Hence "Policy" needs to be changed. Conclusions: Dual Antiplatelet therapy is the standard of care post coronary stenting which has been proved safe and effective. Policy needs to be changed to permit flying with Ticagrelor which is more effective than Clopidogrel and equally safe.

Keywords: antiplatelet drugs, coronary artery disease, stenting, ticagrelor

Procedia PDF Downloads 149
129 Effect of Varying Scaffold Architecture and Porosity of Calcium Alkali Orthophosphate Based-Scaffolds for Bone Tissue Engineering

Authors: D. Adel, F. Giacomini, R. Gildenhaar, G. Berger, C. Gomes, U. Linow, M. Hardt, B. Peleskae, J. Günster, A. Houshmand, M. Stiller, A. Rack, K. Ghaffar, A. Gamal, M. El Mofty, C. Knabe

Abstract:

The goal of this study was to develop 3D scaffolds from a silica containing calcium alkali orthophosphate utilizing two different fabrication processes, first a replica technique namely the Schwartzwalder Somers method (SSM), and second 3D printing, i.e. Rapid prototyping (RP). First, the mechanical and physical properties of the scaffolds (porosity, compressive strength, and solubility) was assessed and second their potential to facilitate homogenous colonization with osteogenic cells and extracellular bone matrix formation throughout the porous scaffold architecture. To this end murine and rat calavarie osteoblastic cells were dynamically seeded on both scaffold types under perfusion with concentrations of 3 million cells. The amount of cells and extracellular matrix as well as osteogenic marker expression was evaluated using hard tissue histology, immunohistochemistry, and histomorphometric analysis. Total porosities of both scaffolds were 86.9 % and 50% for SSM and RP respectively, Compressive strength values were 0.46 ± 0.2 MPa for SSM and 6.6± 0.8 MPa for RP. Regarding the cellular behavior, RP scaffolds displayed a higher cell and matrix percentage of 24.45%. Immunoscoring yielded strong osteocalcin expression of cells and matrix in RP scaffolds and a moderate expression in SSM scaffolds. 3D printed RP scaffolds displayed superior mechanical and biological properties compared to SSM. 3D printed scaffolds represent excellent candidates for bone tissue engineering.

Keywords: calcium alkali orthophosphate, extracellular matrix mineralization, osteoblast differentiation, rapid prototyping, scaffold

Procedia PDF Downloads 302
128 The Contribution of Lower Visual Channels and Evolutionary Origin of the Tunnel Effect

Authors: Shai Gabay

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The tunnel effect describes the phenomenon where a moving object seems to persist even when temporarily hidden from view. Numerous studies indicate that humans, infants, and nonhuman primates possess object persistence, relying on spatiotemporal cues to track objects that are dynamically occluded. While this ability is associated with neural activity in the cerebral neocortex of humans and mammals, the role of subcortical mechanisms remains ambiguous. In our current investigation, we explore the functional contribution of monocular aspects of the visual system, predominantly subcortical, to the representation of occluded objects. This is achieved by manipulating whether the reappearance of an object occurs in the same or different eye from its disappearance. Additionally, we employ Archerfish, renowned for their precision in dislodging insect prey with water jets, as a phylogenetic model to probe the evolutionary origins of the tunnel effect. Our findings reveal the active involvement of subcortical structures in the mental representation of occluded objects, a process evident even in species that do not possess cortical tissue.

Keywords: archerfish, tunnel effect, mental representations, monocular channels, subcortical structures

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127 Auricular Electroacupuncture Rescued Epilepsy Seizure by Attenuating TLR-2 Inflammatory Pathway in the Kainic Acid-Induced Rats

Authors: I-Han Hsiao, Chun-Ping Huang, Ching-Liang Hsieh, Yi-Wen Lin

Abstract:

Epilepsy is chronic brain disorder that results in the sporadic occurrence of spontaneous seizures in the temporal lobe, cerebral cortex, and hippocampus. Clinical antiepileptic medicines are often ineffective or little benefits in the small amount of patients and usually initiate severe side effects. This inflammation contributes to enhanced neuronal excitability and the onset of epilepsy. Auricular electric-stimulation (AES) can increase parasympathetic activity and stimulate the solitary tract nucleus to induce the cholinergic anti-inflammatory pathway. Furthermore, it may be a therapeutic strategy for the treatment of epilepsy. In the present study, we want to investigate the effects of AES on inflammatory mediators in kainic acid (KA)-induced epileptic seizure rats. Experimental KA injection increased expression of TLR-2 pathway associated inflammatory mediators, were further reduced by either 2Hz or 15 Hz AES in the prefrontal cortex, hippocampus, and somatosensory cortex. We suggest that AES can successfully control the epileptic seizure by down-regulation of inflammation signaling pathway.

Keywords: auricular electric-stimulation, epileptic seizures, anti-inflammation

Procedia PDF Downloads 157
126 Advanced Magnetic Resonance Imaging in Differentiation of Neurocysticercosis and Tuberculoma

Authors: Rajendra N. Ghosh, Paramjeet Singh, Niranjan Khandelwal, Sameer Vyas, Pratibha Singhi, Naveen Sankhyan

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Background: Tuberculoma and neurocysticercosis (NCC) are two most common intracranial infections in developing country. They often simulate on neuroimaging and in absence of typical imaging features cause significant diagnostic dilemmas. Differentiation is extremely important to avoid empirical exposure to antitubercular medications or nonspecific treatment causing disease progression. Purpose: Better characterization and differentiation of CNS tuberculoma and NCC by using morphological and multiple advanced functional MRI. Material and Methods: Total fifty untreated patients (20 tuberculoma and 30 NCC) were evaluated by using conventional and advanced sequences like CISS, SWI, DWI, DTI, Magnetization transfer (MT), T2Relaxometry (T2R), Perfusion and Spectroscopy. rCBV,ADC,FA,T2R,MTR values and metabolite ratios were calculated from lesion and normal parenchyma. Diagnosis was confirmed by typical biochemical, histopathological and imaging features. Results: CISS was most useful sequence for scolex detection (90% on CISS vs 73% on routine sequences). SWI showed higher scolex detection ability. Mean values of ADC, FA,T2R from core and rCBV from wall of lesion were significantly different in tuberculoma and NCC (P < 0.05). Mean values of rCBV, ADC, T2R and FA for tuberculoma and NCC were (3.36 vs1.3), (1.09x10⁻³vs 1.4x10⁻³), (0.13 x10⁻³ vs 0.09 x10⁻³) and (88.65 ms vs 272.3 ms) respectively. Tuberculomas showed high lipid peak, more choline and lower creatinine with Ch/Cr ratio > 1. T2R value was most significant parameter for differentiation. Cut off values for each significant parameters have proposed. Conclusion: Quantitative MRI in combination with conventional sequences can better characterize and differentiate similar appearing tuberculoma and NCC and may be incorporated in routine protocol which may avoid brain biopsy and empirical therapy.

Keywords: advanced functional MRI, differentiation, neurcysticercosis, tuberculoma

Procedia PDF Downloads 539
125 Acute Kidney Injury in Severe Trauma Patients: Clinical Presentation and Risk Factor Analysis

Authors: Inkyong Yi

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Acute kidney injury (AKI) in trauma patients is known to be associated with multiple factors, especially shock and consequent inadequate renal perfusion, yet its clinical presentation is little known in severe trauma patients. Our aim was to investigate the clinical presentation of acute kidney injury and its outcome in severe trauma patients at a level I trauma center. A total of 93 consecutive adult trauma patients with an injury severity score (ISS) of more than 15 were analyzed retrospectively from our Level I trauma center data base. Patients with direct renal injury were excluded. Patients were dichotomized into two groups, according to the presence of AKI. Various clinical parameters were compared between two groups, with Student’s T test and Mann-Whitney’s U test. The AKI group was further dichotomized into patients who recovered within seven days, and those who required more than 7days for recovery or those who did not recover at all. Various clinical parameters associated with outcome were further analyzed. Patients with AKI (n=33, 35%) presented with significantly higher age (61.4±17.3 vs. 45.4±17.3, p < 0.0001), incidence of comorbidities (hypertension; 51.5% vs. 13.3%, OR 6.906 95%CI 2.515-18.967, diabetes; 27.3% vs. 6.7%, OR 5.250, 95%CI 1.472-18.722), odds of head and neck trauma (69.7% vs. 41.7%, OR 3.220, 95%CI 1.306-7.942) and presence of shock during emergency room care (66.7% vs 21.7% OR 7.231, 95%CI, 2.798-18.687). Among AKI patients, patients who recovered within 1 week showed lower peak lactate (4.7mmol/L, 95%CI 2.9-6.5 vs 7.3mmol/L, 95%CI 5.0-9.6, p < 0.0287), lesser units of transfusion during first 24 hours (pRBC; 20.4unit, 95%CI 12.5-28.3 vs. 58.9unit, 95%CI 39.4-78.5, p=0.0003, FFP; 16.6unit, 95%CI 6.8-26.4 vs. 56.1unit, 95%CI 26.9-85.2, p=0.0027). In severe trauma patients, patients with AKI showed different clinical presentations and worse outcomes. Initial presence of shock and higher DIC profiles may be important risk factors for AKI in severe trauma patients. In patients with AKI, peak lactate level and amounts of transfusion are related to recovery.

Keywords: acute kidney injury, lactate, transfusion, trauma

Procedia PDF Downloads 179
124 Familial Exome Sequencing to Decipher the Complex Genetic Basis of Holoprosencephaly

Authors: Artem Kim, Clara Savary, Christele Dubourg, Wilfrid Carre, Houda Hamdi-Roze, Valerie Dupé, Sylvie Odent, Marie De Tayrac, Veronique David

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Holoprosencephaly (HPE) is a rare congenital brain malformation resulting from the incomplete separation of the two cerebral hemispheres. It is characterized by a wide phenotypic spectrum and a high degree of locus heterogeneity. Genetic defects in 16 genes have already been implicated in HPE, but account for only 30% of cases, suggesting that a large part of genetic factors remains to be discovered. HPE has been recently redefined as a complex multigenic disorder, requiring the joint effect of multiple mutational events in genes belonging to one or several developmental pathways. The onset of HPE may result from accumulation of the effects of multiple rare variants in functionally-related genes, each conferring a moderate increase in the risk of HPE onset. In order to decipher the genetic basis of HPE, unconventional patterns of inheritance involving multiple genetic factors need to be considered. The primary objective of this study was to uncover possible disease causing combinations of multiple rare variants underlying HPE by performing trio-based Whole Exome Sequencing (WES) of familial cases where no molecular diagnosis could be established. 39 families were selected with no fully-penetrant causal mutation in known HPE gene, no chromosomic aberrations/copy number variants and without any implication of environmental factors. As the main challenge was to identify disease-related variants among a large number of nonpathogenic polymorphisms detected by WES classical scheme, a novel variant prioritization approach was established. It combined WES filtering with complementary gene-level approaches: transcriptome-driven (RNA-Seq data) and clinically-driven (public clinical data) strategies. Briefly, a filtering approach was performed to select variants compatible with disease segregation, population frequency and pathogenicity prediction to identify an exhaustive list of rare deleterious variants. The exome search space was then reduced by restricting the analysis to candidate genes identified by either transcriptome-driven strategy (genes sharing highly similar expression patterns with known HPE genes during cerebral development) or clinically-driven strategy (genes associated to phenotypes of interest overlapping with HPE). Deeper analyses of candidate variants were then performed on a family-by-family basis. These included the exploration of clinical information, expression studies, variant characteristics, recurrence of mutated genes and available biological knowledge. A novel bioinformatics pipeline was designed. Applied to the 39 families, this final integrated workflow identified an average of 11 candidate variants per family. Most of candidate variants were inherited from asymptomatic parents suggesting a multigenic inheritance pattern requiring the association of multiple mutational events. The manual analysis highlighted 5 new strong HPE candidate genes showing recurrences in distinct families. Functional validations of these genes are foreseen.

Keywords: complex genetic disorder, holoprosencephaly, multiple rare variants, whole exome sequencing

Procedia PDF Downloads 181
123 Negative RT-PCR in a Newborn Infected with Zika Virus: A Case Report

Authors: Vallejo Michael, Acuña Edgar, Roa Juan David, Peñuela Rosa, Parra Alejandra, Casallas Daniela, Rodriguez Sheyla

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Congenital Zika Virus Syndrome is an entity composed by a variety of birth defects presented in newborns that have been exposed to the Zika Virus during pregnancy. The syndrome characteristic features are severe microcephaly, cerebral tissue abnormalities, ophthalmological abnormalities such as uveitis and chorioretinitis, arthrogryposis, clubfoot deformity and muscular tone abnormalities. The confirmatory test is the Reverse transcription polymerase chain reaction (RT-PCR) associated to the physical findings. Here we present the case of a newborn with microcephaly whose mother presented a confirmed Zika Virus infection during the third trimester of pregnancy, despite of the evident findings and the history of Zika infection the RT-PCR in amniotic and cerebrospinal fluid of the newborn was negative. RT-PCR has demonstrated a low sensibility in samples with low viral loads, reason why, we propose a clinical diagnosis in patients with clinical history of Zika Virus infection during pregnancy accompanied by evident clinical manifestations of the child.

Keywords: congenital, Zika virus, microcephaly, reverse transcriptase polymerase chain reaction

Procedia PDF Downloads 183
122 Development of Electrospun Membranes with Defined Polyethylene Collagen and Oxide Architectures Reinforced with Medium and High Intensity Statins

Authors: S. Jaramillo, Y. Montoya, W. Agudelo, J. Bustamante

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Cardiovascular diseases (CVD) are related to affectations of the heart and blood vessels, within these are pathologies such as coronary or peripheral heart disease, caused by the narrowing of the vessel wall (atherosclerosis), which is related to the accumulation of Low-Density Lipoproteins (LDL) in the arterial walls that leads to a progressive reduction of the lumen of the vessel and alterations in blood perfusion. Currently, the main therapeutic strategy for this type of alteration is drug treatment with statins, which inhibit the enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA reductase), responsible for modulating the rate of cholesterol production and other isoprenoids in the mevalonate pathway. This enzyme induces the expression of LDL receptors in the liver, increasing their number on the surface of liver cells, reducing the plasma concentration of cholesterol. On the other hand, when the blood vessel presents stenosis, a surgical procedure with vascular implants is indicated, which are used to restore circulation in the arterial or venous bed. Among the materials used for the development of vascular implants are Dacron® and Teflon®, which perform the function of re-waterproofing the circulatory circuit, but due to their low biocompatibility, they do not have the ability to promote remodeling and tissue regeneration processes. Based on this, the present research proposes the development of a hydrolyzed collagen and polyethylene oxide electrospun membrane reinforced with medium and high-intensity statins, so that in future research it can favor tissue remodeling processes from its microarchitecture.

Keywords: atherosclerosis, medium and high-intensity statins, microarchitecture, electrospun membrane

Procedia PDF Downloads 109
121 Radio Labeling and Characterization of Cysteine and Its Derivatives with Tc99m and Their Bio-Distribution

Authors: Rabia Ashfaq, Saeed Iqbal, Atiq ur Rehman, Irfanullah Khan

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An extensive series of radiopharmaceuticals have been explored in order to discover a better brain tumour diagnostic agent. Tc99m labelling with cysteine and its derivatives in liposomes shows effective tagging of about 70% to 80 %. Due to microscopic size it successfully crossed the brain barrier in 2 minutes which gradually decreases in 5 to 15 minutes. HMPAO labelled with Tc99m is another important radiopharmaceutical used to study brain perfusion but it comes with a flaw that it’s only functional during epilepsy. 1, 1 ECD is purely used in Tc99m ECD formulation; because it not only tends to cross the blood brain barrier but it can be metabolized which can be easily entrapped in human brain. Radio labelling of Cysteine with Tc99m at room temperature was performed which yielded no good results. Hence cysteine derivatives with salicylaldehyde were prepared that produced about 75 % yield for ligand. In order to perform it’s radio labelling a suitable solvent DMSO was selected and physical parameters were performed. Elemental analyser produced remarkably similar results for ligand as reported in literature. IR spectra of Ligand in DMSO concluded in the absence of SH stretch and presence of N-H vibration. Thermal analysis of the ligand further suggested its decomposition pattern with no distinct curve for a melting point. Radio labelling of ligand was performed which produced excellent results giving up to 88% labelling at pH 5.0. Clinical trials using Rabbit were performed after validating the products reproducibility. The radiopharmaceutical prepared was injected into the rabbit. Dynamic as well as static study was performed under the SPECT. It showed considerable uptake in the kidneys and liver considering it suitable for the Hypatobilliary study.

Keywords: marcapto compounds, 99mTc - radiolabeling, salicylaldicysteine, thiozolidine

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120 The Important of Nutritional Status in Rehabilitation of Children with CP: Saudi Perspective

Authors: Reem Al-Garni

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Malnutrition is a global epidemic, but the under-weight or Failure-To-Thrive risk is increasing in rehabilitation setting and considered one of the contribution factor for developmental delay. Beside the consequences of malnutrition on children growth and development, there are other side-effects that might delay or hold the progress of rehabilitation. The awareness for malnutrition must be raised and discussed by the rehabilitation team, to promote the treatment and to optimize the client care. The solution can start from food supplements intake and / or Enteral Nutrition plan, depending on the malnutrition level and to reach the goal, the medical team should to work together in order to provide comprehensive treatment and to help the family to be able to manage their child condition. We have explore the outcomes of rehabilitation between the children with CP whose diagnosed with malnutrition and children with normal body Wight Over a period of 4 months who received 4-6 weeks of rehabilitation two hours daily by using WeeFIM score to measure rehabilitation outcomes. WeeFIM measures and covers various domains, such as: self-care, mobility, locomotion, communication and other psycho-social aspects. Our findings reported that children with normal body Wight has better outcomes and improvement comparing with children with malnutrition for the entire study sample.

Keywords: Cerebral Palsy (CP), pediatric Functional Independent Measure (WeeFIM), rehabilitation, malnutrition

Procedia PDF Downloads 295
119 In Situ Volume Imaging of Cleared Mice Seminiferous Tubules Opens New Window to Study Spermatogenic Process in 3D

Authors: Lukas Ded

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Studying the tissue structure and histogenesis in the natural, 3D context is challenging but highly beneficial process. Contrary to classical approach of the physical tissue sectioning and subsequent imaging, it enables to study the relationships of individual cellular and histological structures in their native context. Recent developments in the tissue clearing approaches and microscopic volume imaging/data processing enable the application of these methods also in the areas of developmental and reproductive biology. Here, using the CLARITY tissue procedure and 3D confocal volume imaging we optimized the protocol for clearing, staining and imaging of the mice seminiferous tubules isolated from the testes without cardiac perfusion procedure. Our approach enables the high magnification and fine resolution axial imaging of the whole diameter of the seminiferous tubules with possible unlimited lateral length imaging. Hence, the large continuous pieces of the seminiferous tubule can be scanned and digitally reconstructed for the study of the single tubule seminiferous stages using nuclear dyes. Furthermore, the application of the antibodies and various molecular dyes can be used for molecular labeling of individual cellular and subcellular structures and resulting 3D images can highly increase our understanding of the spatiotemporal aspects of the seminiferous tubules development and sperm ultrastructure formation. Finally, our newly developed algorithms for 3D data processing enable the massive parallel processing of the large amount of individual cell and tissue fluorescent signatures and building the robust spermatogenic models under physiological and pathological conditions.

Keywords: CLARITY, spermatogenesis, testis, tissue clearing, volume imaging

Procedia PDF Downloads 124
118 Advancing Epilepsy Diagnosis through EEG Analysis and Independent Component Analysis Algorithms

Authors: Eyad Talal Attar

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Epilepsy is a prevalent neurological condition that impacts a considerable population of around 50 million individuals globally, rendering it one of the most widespread neurological disorders. The condition is distinguished by recurring seizures, which are abrupt and transient disruptions in a cerebral activity that can induce alterations in perception, conduct, and awareness. Seizures can be classified as focal or generalized, based on the specific site and scope of the atypical brain activity. Focal seizures are identified by confinement to a particular brain area and can elicit localized manifestations. Generalized seizures are identified by extensive electrical activity throughout the brain, and they can appear in various symptoms such as convulsions, muscle rigidity, and loss of consciousness. This study represents seven individuals chosen according to the number of seizures in the range of three to five seizure and investigates the ability to detect brain seizure activity. The EEG recording Siena Scalp Database was used from PhysioNet databases. EEGLAB is a robust tool utilized for processing and analyzing electroencephalogram (EEG) data and is used to analyze the raw data. The efficacy of Independent Component Analysis ICA algorithms has been demonstrated in the separation of arterial EEG sources and neuronal-generated EEG sources.

Keywords: EEG, MATLAB software, power spectral density, PSD, signal analysis, attention, alpha, beta, gamma

Procedia PDF Downloads 35
117 On the Homology Modeling, Structural Function Relationship and Binding Site Prediction of Human Alsin Protein

Authors: Y. Ruchi, A. Prerna, S. Deepshikha

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Amyotrophic lateral sclerosis (ALS), also known as “Lou Gehrig’s disease”. It is a neurodegenerative disease associated with degeneration of motor neurons in the cerebral cortex, brain stem, and spinal cord characterized by distal muscle weakness, atrophy, normal sensation, pyramidal signs and progressive muscular paralysis reflecting. ALS2 is a juvenile autosomal recessive disorder, slowly progressive, that maps to chromosome 2q33 and is associated with mutations in the alsin gene, a putative GTPase regulator. In this paper we have done homology modeling of alsin2 protein using multiple templates (3KCI_A, 4LIM_A, 402W_A, 4D9S_A, and 4DNV_A) designed using the Prime program in Schrödinger software. Further modeled structure is used to identify effective binding sites on the basis of structural and physical properties using sitemap program in Schrödinger software, structural and function analysis is done by using Prosite and ExPASy server that gives insight into conserved domains and motifs that can be used for protein classification. This paper summarizes the structural, functional and binding site property of alsin2 protein. These binding sites can be potential drug target sites and can be used for docking studies.

Keywords: ALS, binding site, homology modeling, neuronal degeneration

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116 Effects of Using Clinical Practice Guidelines for Caring for Patients with Severe Sepsis or Septic Shock on Clinical Outcomes Based on the Sepsis Bundle Protocol at the ICU of Songkhla Hospital Thailand

Authors: Pornthip Seangsanga

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Sepsis or septic shock needs urgent care because it is a cause of the high mortality rate if patients do not receive timely treatment. Songkhla Hospital does not have a clear system or clinical practice guidelines for treatment of patients with severe sepsis or septic shock, which contributes to the said problem.To compare clinical outcomes based on the protocol after using the clinical guidelines between the Emergency Room, Intensive Care Unit, and the Ward. This quasi-experimental study was conducted on the population and 50 subjects who were diagnosed with severe sepsis or septic shock from December 2013 to May 2014. The data were collected using a nursing care and referring record form for patients with severe sepsis or septic shock at Songkhla Hospital. The record form had been tested for its validity by three experts, and the IOC was 1.The mortality rate in patients with severe sepsis or septic shock who were moved from the ER to the ICU was significantly lower than that of those patients moved from the Ward to the ICU within 48 hours. This was because patients with severe sepsis or septic shock who were moved from the ER to the ICU received more fluid within the first six hours according to the protocol which helped patients to have adequate tissue perfusion within the first six hours, and that helped improve blood flow to the kidneys, and the patients’ urine was found to be with a higher quantity of 0.5 cc/kg/hr, than those patients who were moved from the Ward to the ICU. This study shows that patients with severe sepsis or septic shock need to be treated immediately. Using the clinical practice guidelines along with timely diagnosis and treatment based on the sepsis bundle in giving sufficient and suitable amount of fluid to help improve blood circulation and blood pressure can clearly prevent or reduce severity of complications.

Keywords: clinical practice guidelines, caring, septic shock, sepsis bundle protocol

Procedia PDF Downloads 280
115 A Radiomics Approach to Predict the Evolution of Prostate Imaging Reporting and Data System Score 3/5 Prostate Areas in Multiparametric Magnetic Resonance

Authors: Natascha C. D'Amico, Enzo Grossi, Giovanni Valbusa, Ala Malasevschi, Gianpiero Cardone, Sergio Papa

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Purpose: To characterize, through a radiomic approach, the nature of areas classified PI-RADS (Prostate Imaging Reporting and Data System) 3/5, recognized in multiparametric prostate magnetic resonance with T2-weighted (T2w), diffusion and perfusion sequences with paramagnetic contrast. Methods and Materials: 24 cases undergoing multiparametric prostate MR and biopsy were admitted to this pilot study. Clinical outcome of the PI-RADS 3/5 was found through biopsy, finding 8 malignant tumours. The analysed images were acquired with a Philips achieva 1.5T machine with a CE- T2-weighted sequence in the axial plane. Semi-automatic tumour segmentation was carried out on MR images using 3DSlicer image analysis software. 45 shape-based, intensity-based and texture-based features were extracted and represented the input for preprocessing. An evolutionary algorithm (a TWIST system based on KNN algorithm) was used to subdivide the dataset into training and testing set and select features yielding the maximal amount of information. After this pre-processing 20 input variables were selected and different machine learning systems were used to develop a predictive model based on a training testing crossover procedure. Results: The best machine learning system (three-layers feed-forward neural network) obtained a global accuracy of 90% ( 80 % sensitivity and 100% specificity ) with a ROC of 0.82. Conclusion: Machine learning systems coupled with radiomics show a promising potential in distinguishing benign from malign tumours in PI-RADS 3/5 areas.

Keywords: machine learning, MR prostate, PI-Rads 3, radiomics

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114 Dynamics of Follicle Vascular Perfusion, Dimensions, Antrum Growth, Circulating Angiogenic Mediators from Deviation to Ovulation

Authors: Elshymaa A. Abdelnaby, Amal M. Abo El-Maaty

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This study aimed to investigate dynamics of dominant and subordinate follicles change in dimensions, vascularity and angiogenic hormones after completing deviation till ovulation. Five cyclic mares were subjected to daily blood sampling and rectal Doppler ultrasonographic examination along two estrous cycles. Using electronic calipers, three diameters were recorded for each follicle to estimate area and volume. Leptin, Insulin-like growth factor-I (IGF-1), nitric oxide (NO) and estradiol (E2) were measured. Area of color- and power- Doppler modes with area and circumference of the first (preovulatory) and subordinate follicles were measured in pixels. Follicles were classified into F1O (preovulatory), F2O (subordinate), F3O (third ovulatory) on the dominant ovary and F1C (first contra) and F2C (second contra) on the contralateral ovary. Days before ovulation significantly (P < 0.0001) affected diameter, circumference, area, volume, area/pixel and antrum area of the preovulatory follicle. With the increase of diameter, area, volume area/pixel, antrum area/pixel and circumference of F1O, those of all subordinates were decreasing. The blue blood flow area, power and power minus red blood flow area of F1O increased from day -6 till day of ovulation (day 0), but red blood flow area significantly decreased. F1O had the lowest percent of colored pixels and percent of the colored pixels without antrum. Estradiol and leptin increased from day -6 till day 0 but IGF-1 decreased till day -1 but NO achieved a peak on day -3 then decreased till day 0. In conclusion, antrum growth, blood flow and angiogenic hormones play a role in maturation and ovulation of the dominant follicle in mares.

Keywords: angiogenic hormones, blood flow, mare, preovulatory follicle

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113 Clinical Utility of Salivary Cytokines for Children with Attention Deficit Hyperactivity Disorder

Authors: Masaki Yamaguchi, Daimei Sasayama, Shinsuke Washizuka

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The goal of this study was to examine the possibility of salivary cytokines for the screening of attention deficit hyperactivity disorder (ADHD) in children. We carried out a case-control study, including 19 children with ADHD and 17 healthy children (controls). A multiplex bead array immunoassay was used to conduct a multi-analysis of 27 different salivary cytokines. Six salivary cytokines (interleukin (IL)-1β, IL-8, IL12p70, granulocyte colony-stimulating factor (G-CSF), interferon gamma (IFN-γ), and vascular endothelial growth factor (VEGF)) were significantly associated with the presence of ADHD (p < 0.05). An informative salivary cytokine panel was developed using VEGF by logistic regression analysis (odds ratio: 0.251). Receiver operating characteristic analysis revealed that assessment of a panel using VEGF showed “good” capability for discriminating between ADHD patients and controls (area under the curve: 0.778). ADHD has been hypothesized to be associated with reduced cerebral blood flow in the frontal cortex, due to reduced VEGF levels. Our study highlights the possibility of utilizing differential salivary cytokine levels for point-of-care testing (POCT) of biomarkers in children with ADHD.

Keywords: cytokine, saliva, attention deficit hyperactivity disorder, child

Procedia PDF Downloads 121
112 Consequence of Multi-Templating of Closely Related Structural Analogues on a Chitosan-Methacryllic Acid Molecularly Imprinted Polymer Matrix-Thermal and Chromatographic Traits

Authors: O.Ofoegbu, S. Roongnapa, A.N. Eboatu

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Most polluted environments, most challengingly, aerosol types, contain a cocktail of different toxicants. Multi-templating of matrices have been the recent target by researchers in a bid to solving complex mixed-toxicant challenges using single or common remediation systems. This investigation looks at the effect of such multi-templated system vis-a-vis the synthesis by non-covalent interaction, of a molecularly imprinted polymer architecture using nicotine and its structural analogue Phenylalanine amide individually and, in the blend, (50:50), as template materials in a Chitosan-Methacrylic acid functional monomer matrix. The temperature for polymerization is 60OC and time for polymerization, 12hrs (water bath heating), 4mins for (microwave heating). The characteristic thermal properties of the molecularly imprinted materials are investigated using Simultaneous Thermal Analysis (STA) profiling, while the absorption and separation efficiencies based on the relative retention times and peak areas of templates were studied amongst other properties. Transmission Electron Microscopy (TEM) results obtained, show the creation of heterogeneous nanocavities, regardless, the introduction of Caffeine a close structural analogue presented near-zero perfusion. This confirms the selectivity and specificity of the templated polymers despite its dual-templated nature. The STA results presented the materials as having decomposition temperatures above 250OC and a relative loss in mass of less than19% over a period within 50mins of heating. Consequent to this outcome, multi-templated systems can be fabricated to sequester specifically and selectively targeted toxicants in a mixed toxicant populated system effectively.

Keywords: chitosan, dual-templated, methacrylic acid, mixed-toxicants, molecularly-imprinted-polymer

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111 Accurate Cortical Reconstruction in Narrow Sulci with Zero-Non-Zero Distance (ZNZD) Vector Field

Authors: Somojit Saha, Rohit K. Chatterjee, Sarit K. Das, Avijit Kar

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A new force field is designed for propagation of the parametric contour into deep narrow cortical fold in the application of knowledge based reconstruction of cerebral cortex from MR image of brain. Designing of this force field is highly inspired by the Generalized Gradient Vector Flow (GGVF) model and markedly differs in manipulation of image information in order to determine the direction of propagation of the contour. While GGVF uses edge map as its main driving force, the newly designed force field uses the map of distance between zero valued pixels and their nearest non-zero valued pixel as its main driving force. Hence, it is called Zero-Non-Zero Distance (ZNZD) force field. The objective of this force field is forceful propagation of the contour beyond spurious convergence due to partial volume effect (PVE) in to narrow sulcal fold. Being function of the corresponding non-zero pixel value, the force field has got an inherent property to determine spuriousness of the edge automatically. It is effectively applied along with some morphological processing in the application of cortical reconstruction to breach the hindrance of PVE in narrow sulci where conventional GGVF fails.

Keywords: deformable model, external force field, partial volume effect, cortical reconstruction, MR image of brain

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110 Can Demyelinative Lesion Cause To Behaviora Change?

Authors: Arezou Hajhashemi, Karim Asgari, Masoud Etemadifar, Maryam Keyvani, Ali Hekmatnia

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Multiple Sclerosis (MS) is one of the most prevalent demyelinating diseases in CNS. As in other chronic cerebral diseases, impairment in cognitive functioning and in memory is popular. Because of the inflammatory and demyelinating nature of the disease, the localization of plaques in different parts of the Prefrontal and Limbic System, may lead to memorial symptoms. This investigation was intended to study relationship between frequency of plaques and memorial symptoms arising from dysfunction limbic system and prefrontal of patients with MS. The sample was selected randomly from patients with MS with memory problem, who have been referred to Isfahan Multiple Sclerosis Society. Brain System Test and Memory Test was administered to the sample, and their MRI's were analyzed by specialist in order to indentify two different parts of plaques. The data was analyzed by SPSS. The results showed that there were significant relationship between MS plaques and prefrontal's dysfunction and memorial symptom related to prefrontal area; however, there were no significant relationship between MS plaques and limbic system's dysfunction and memorial symptoms related to limbic system area. The results of this study suggest that memorial symptoms due to injury regions of the brain have the most significant relationship to prefrontal. Better judgment about these results needs more studies in future.

Keywords: multiple sclerosis, magnetic image, brain injury, behavior disorder

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109 A Promising Thrombolytic and Anticoagulant Serine Protease Purified from Lug Worms Inhabiting Tidal Flats

Authors: Hye Jin Kim, Hwa Sung Shin

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Ischemic stroke means the caused brain damage due to neurological defects, occurring occlusion of cerebral vascular resulting in thrombus or embolism. t-PA (tissue Plasminogen Activator) is the only thrombolytic agent passed the FDA (Food and Drug Administration). However, t-PA directly dissolves the thrombus (direct activity) through fibrinolysis, showing side effects such as re-occlusion. In this study, we evaluated the thrombolytic activities of the serine protease extracted from lugworms inhabiting tidal flats. The new serine protease identified as 38 kDa by SDS-PAGE was not toxic to brain endothelial cells line (hCMEC/D3). Also, the plasmin synthesis inhibition activity (indirect activity) of the new serine protease was confirmed through fibrin zymography assay and fibrin plate assay. It was higher than direct activity as compared to u-PA (urokinase Plasminogen Activator). The activities were found to be maintained at a wide range of temperature (4-70 ℃) and pH 7-10 compared to previous thrombolytic agents from the azocasein assay. In addition, the new serine protease has shown anticoagulant activity from fibrinogenolytic activity assay. In conclusion, the serine protease in lug worms inhabiting the tidal flats could be considered a promising thrombolytic candidate for the treatment of ischemic stroke.

Keywords: alkaline serine protease, bifunctional thrombolytic activity, fibrinolytic activity, ischemic stroke, lug worms

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108 Shear Stress and Oxygen Concentration Manipulation in a Micropillars Microfluidic Bioreactor

Authors: Deybith Venegas-Rojas, Jens Budde, Dominik Nörz, Manfred Jücker, Hoc Khiem Trieu

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Microfluidics is a promising approach for biomedicine cell culture experiments with microfluidic bioreactors (MBR), which can provide high precision in volume and time control over mass transport and microenvironments in small-scale studies. Nevertheless, shear stress and oxygen concentration are important factors that affect the microenvironment and then the cell culture. It is presented a novel MBR design in which differences in geometry, shear stress, and oxygen concentration were studied and optimized for cell culture. The aim is to mimic the in vivo condition with biocompatible materials and continuous perfusion of nutrients, a healthy shear stress, and oxygen concentration. The design consists of a capture system of PDMS micropillars which keep cells in place, so it is not necessary any hydrogel or complicated scaffolds for cells immobilization. Besides, the design allows continuous supply with nutrients or even any other chemical for cell experimentation. Finite element method simulations were used to study and optimize the effect of parameters such as flow rate, shear stress, oxygen concentration, micropillars shape, and dimensions. The micropillars device was fabricated with microsystem technology such as soft-lithography, deep reactive ion etching, self-assembled monolayer, replica molding, and oxygen plasma bonding. Eight different geometries were fabricated and tested, with different flow rates according to the simulations. During the experiments, it was observed the effect of micropillars size, shape, and configuration for stability and shear stress control when increasing flow rate. The device was tested with several successful HepG2 3D cell cultures. With this MBR, the aforementioned parameters can be controlled in order to keep a healthy microenvironment according to specific necessities of different cell types, with no need of hydrogels and can be used for a wide range of experiments with cells.

Keywords: cell culture, micro-bioreactor, microfluidics, micropillars, oxygen concentration, shear stress

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107 Expression of Somatostatin and Neuropeptide Y in Dorsal Root Ganglia Following Hind Paw Incision in Rats

Authors: Anshu Bahl, Saroj Kaler, Shivani Gupta, S B Ray

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Background: Somatostatin is an endogenous regulatory neuropeptide. Somatostatin and its analogues play an important role in neuropathic and inflammatory pain. Neuropeptide Y is extensively distributed in the mammalian nervous system. NPY has an important role in blood pressure, circadian rhythm, obesity, appetite and memory. The purpose was to investigate somatostatin and NPY expression in dorsal root ganglia during pain. The plantar incision model in rats is similar to postoperative pain in humans. Methods: 24 adult male Sprague dawley rats were distributed randomly into two groups – Control (n=6) and incision (n=18) groups. Using Hargreaves apparatus, thermal hyperalgesia behavioural test for nociception was done under basal condition and after surgical incision in right hind paw at different time periods (day 1, 3 and 5). The plantar incision was performed as per standard protocol. Perfusion was done using 4% paraformaldehyde followed by extraction of dorsal root ganglia at L4 level. The tissue was processed for immunohistochemical localisation for somatostatin and neuropeptide Y. Results: Post incisional groups (day 1, 3 and 5) exhibited significant decrease of paw withdrawal latency as compared to control groups. Somatostatin expression was noted under basal conditions. It decreased on day 1, but again gradually increased on day 3 and further on day five post incision. The expression of Neuropeptide Y was noted in the cytoplasm of dorsal root ganglia under basal conditions. Compared to control group, expression of neuropeptide Y decreased on day one after incision, but again gradually increased on day 3. Maximum expression was noted on day five post incision. Conclusion: Decrease in paw withdrawal latency indicated nociception, particularly on day 1. In comparison to control, somatostatin and NPY expression was decreased on day one post incision. This could be correlated with increased axoplasmic flow towards the spinal cord. Somatostatin and NPY expression was maximum on day five post incision. This could be due to decreased migration from the site of synthesis towards the spinal cord.

Keywords: dorsal root ganglia, neuropeptide y, postoperative pain, somatostatin

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106 Bilateral Choroidal Metastases as the Presenting Manifestation of Lung Adenocarcinoma in a Young, Non-smoking Female: A Case Report

Authors: Paras Agarwal

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Background: Initially believed to be rare, metastases to the eye are the most common ocular malignancy. The choroid’s high perfusion rate not only makes it the most susceptible ocular site for tumour seeding, but also promotes its growth. The cancers most frequently responsible for choroidal metastases originate from the breast and lung, although a significant proportion have unidentified primaries at the time of presentation. Case Presentation: This case report describes a 34 year old female presenting to the ophthalmology department with a one month history of painless distorted vision. On fundus examination, she was noted to have bilateral choroidal lesionsand subsequently underwent a comprehensive diagnostic work-up. The patient was diagnosed with metastatic pulmonary adenocarcinoma, despite lacking conventional risk factors. As she was found to have a mutation in EGFR, the patient was commenced on tyrosine-kinase inhibition with afatinib. The choroidal lesions regressed with a significant improvement in visual acuity and a dramatic anatomical reduction of the choroidal masses. Conclusions: Our case demonstrates the importance of considering metastases as a differential diagnosis for choroidal lesions. Appropriate and thorough history-taking, examination and investigations may be required in order to deduce the underlying cause. Our case is unusual in view of the choroidal lesion being the primary manifestation of metastatic lung cancer in a young patient with no known risk factors. Early recognition of choroidal metastases is important as it is often the first sign of tumour dissemination and will prompt earlier treatment with systemic medications such as chemotherapy, immunotherapy, targeted therapy or hormonal therapy. Our case report also demonstrates the efficacy of afatinib for the treatment of choroidal metastases, with morphological and functional improvements observed with regard to the choroidal metastatic tumour.

Keywords: choroidal neoplasm, choroidal naevus, pulmonary adenocarcinoma, metastases, lung cancer

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105 Hepatitis B Prevalence in Institutionalized Intellectually Disabled Children

Authors: Maryam Vaezjalali, Foad Davoodbeglou, Mehrnaz Mesdaghi, Hossein Goudarzi, Fariba Shojaei, Hourieh Aram

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Introduction: Hepatitis B virus (HBV) infection causes chronic infection in human population, with high mortality. Some people are more susceptible to this infection. One of the high risk communities is mentally retarded children, who are institutionalized. Special conditions in these centers predispose children for HBV infection and transmission to healthy people. In this study our objective was to determine the prevalence of HBV infection among institutionalized mentally retarded children and study its associated risk factors. Materials and methods: In this study, 250 mentally retarded children (younger than 14 years old) were included. They were living in 5 nursing institutions, located in different parts of Tehran. HBsAg was measured in the sera of these patients by ELISA method. Results: Among 250 children, 20 children (8%) were HBsAg positive. HBV infection in girls was more than boys (11% to 5.6%). Among the types of mental retardation, children with cerebral palsy had the highest positive result for HBsAg. The most HBV infection (28.5%) was seen in children with longest duration of being institutionalized (10 to 11 years). Vaccinated children were more HBsAg positive (8.7%) than non-vaccinated children (5.3%). However, no significant relationship was observed between any of these factors and HBsAg positivity. Conclusion: Despite improvement of people’s health condition and implementation of HBV vaccination, the prevalence of HBV infection is high in institutionalized mentally retarded children, which highlights the need for active measures to reduce this infection among this high risk population.

Keywords: hepatitis B virus, HBV vaccine, intellectually disabled children, mentally retarded

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104 The Great Mimicker: A Case of Disseminated Tuberculosis

Authors: W. Ling, Mohamed Saufi Bin Awang

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Introduction: Mycobacterium tuberculosis post a major health problem worldwide. Central nervous system (CNS) infection by mycobacterium tuberculosis is one of the most devastating complications of tuberculosis. Although with advancement in medical fields, we are yet to understand the pathophysiology of how mycobacterium tuberculosis was able to cross the blood-brain barrier (BBB) and infect the CNS. CNS TB may present with nonspecific clinical symptoms which can mimic other diseases/conditions; this is what makes the diagnosis relatively difficult and challenging. Public health has to be informed and educated about the spread of TB, and early identification of TB is important as it is a curable disease. Case Report: A young 21-year-old Malay gentleman was initially presented to us with symptoms of ear discharge, tinnitus, and right-sided headache for the past one year. Further history reveals that the symptoms have been mismanaged and neglected over the period of 1 year. Initial investigation reveals features of inflammation of the ear. Further imaging showed the feature of chronic inflammation of the otitis media and atypical right cerebral abscess, which has the same characteristic features and consistency. He further underwent a biopsy, and results reveal positive Mycobacterium tuberculosis of the otitis media. With the results and the available imaging, we were certain that this is likely a case of disseminated tuberculosis causing CNS TB. Conclusion: We aim to highlight the challenge and difficult face in our health care system and public health in early identification and treatment.

Keywords: central nervous system tuberculosis, intracranial tuberculosis, tuberculous encephalopathy, tuberculous meningitis

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103 Trigonella foenum-graecum Seeds Extract as Therapeutic Candidate for Treatment of Alzheimer's Disease

Authors: Mai M. Farid, Ximeng Yang, Tomoharu Kuboyama, Yuna Inada, Chihiro Tohda

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Intro: Trigonella foenum-graecum (Fenugreek), from Fabaceae family is a well-known plant traditionally used as food and medicine. Many pharmacological effects of Trigonella foenum- graecum seeds extract (TF extract) were evaluated such as anti-diabetic, anti-tumor and anti-dementia effects using in vivo models. Regarding the anti-dementia effects of TF extract, diabetic rats, aluminum chloride-induced amnesia rats and scopolamine-injected mice were used previously for evaluation, which are not well established as Alzheimer’s disease models. In addition, those previous studies, active constituents in TF extract for memory function were not identified. Method: This study aimed to clarify the effect of TF extract on Alzheimer’s disease model, 5XFAD mouse that overexpresses mutated APP and PS1 genes and determine the major active constituent in the brain after oral intake of TF extract. Results: Trigonelline was detected in the cerebral cortex of 5XFAD mice after 24 hours of oral administration of TF extract by LC-MS/MS. Oral administration of TF extract for 17 days improved object location memory in 5XFAD mice. Conclusion: These results suggest that TF extract and its active constituents could be an expected therapeutic candidate for Alzheimer’s disease.

Keywords: Alzheimer's disease, LC-MS/MS, memory recovery, Trigonella foenum-graecum Seeds, 5XFAD mice

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102 Myocardial Reperfusion Injury during Percutaneous Coronary Intervention in Patient with Triple-Vessel Disease in Limited Resources Hospital: A Case Report

Authors: Fanniyah Anis, Bram Kilapong

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Myocardial reperfusion injury is defined as the cellular damage that results from a period of ischemia, followed by the reestablishment of the blood supply to the infarcted tissue. Ventricular tachycardia is one of the most commonly encountered reperfusion arrhythmia as one of the types of myocardial perfusion injury. Prompt and early treatment can reduce mortality, despite limited resources of the hospital in high risk patients with history of triple vessel disease. Case report, Male 53 years old has been diagnosed with NSTEMI with 3VD and comorbid disease of Hypertension and has undergone revascularization management with Percutaneous coronary intervention. Ventricular tachycardia leading to cardiac arrest occurred right after the stent was inserted. Resuscitation was performed for almost 2 hours until spontaneous circulation returned. Patient admitted in ICU with refractory cardiac shock despite using combination of ionotropic and vasopressor agents under standard non-invasive monitoring due to the limitation of the hospital. Angiography was performed again 5 hours later to exclude other possibilities of blockage of coronary arteries and conclude diagnosis of myocardial reperfusion injury. Patient continually managed with combination of antiplatelet agents and maintenance dose of anti-arrhythmia agents. The handling of the patient was to focus more on supportive and preventive from further deteriorating of the condition. Patient showed clinically improvement and regained consciousness within 24 hours. Patient was successfully discharged from ICU within 3 days without any neurological sequela and was discharge from hospital after 3 days observation in general ward. Limited Resource of hospital did not refrain the physician from attaining a good outcome for this myocardial reperfusion injury case and angiography alone can be used to confirm the diagnosis of myocardial reperfusion injury.

Keywords: limited resources hospital, myocardial reperfusion injury, prolonged resuscitation, refractory cardiogenic shock, reperfusion arrhythmia, revascularization, triple-vessel disease

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101 Embolism: How Changes in Xylem Sap Surface Tension Affect the Resistance against Hydraulic Failure

Authors: Adriano Losso, Birgit Dämon, Stefan Mayr

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In vascular plants, water flows from roots to leaves in a metastable state, and even a small perturbation of the system can lead a sudden transition from the liquid to the vapor phase, resulting in xylem embolism (cavitation). Xylem embolism, induced by drought stress and/or freezing stress is caused by the aspiration of gaseous bubbles into xylem conduits from adjacent gas-filled compartments through pit membrane pores (‘air seeding’). At water potentials less negative than the threshold for air seeding, the surface tension (γ) stabilizes the air-water interface and thus prevents air from passing the pit pores. This hold is probably also true for conifers, where this effect occurs at the edge of the sealed torus. Accordingly, it was experimentally demonstrated that γ influences air seeding, but information on the relevance of this effect under field conditions is missing. In this study, we analyzed seasonal changes in γ of the xylem sap in two conifers growing at the alpine timberline (Picea abies and Pinus mugo). In addition, cut branches were perfused (40 min perfusion at 0.004 MPa) with different γ solutions (i.e. distilled and degassed water, 2, 5 and 15% (v/v) ethanol-water solution corresponding to a γ of 74, 65, 55 and 45 mN m-1, respectively) and their vulnerability to drought-induced embolism analyzed via the centrifuge technique (Cavitron). In both species, xylem sap γ changed considerably (ca. 53-67 and ca. 50-68 mN m-1 in P. abies and P. cembra, respectively) over the season. Branches perfused with low γ solutions showed reduced resistance against drought-induced embolism in both species. A significant linear relationship (P < 0.001) between P12, P50 and P88 (i.e. water potential at 12, 50 and 88% of the loss of conductivity) and xylem sap γ was found. Based on this correlation, a variation in P50 between -3.10 and -3.83 MPa (P. abies) and between -3.21 and -4.11 MPa (P. mugo) over the season could be estimated. Results demonstrate that changes in γ of the xylem sap can considerably influence a tree´s resistance to drought-induced embolism. They indicate that vulnerability analyses, normally conducted at a γ near that of pure water, might often underestimate vulnerabilities under field conditions. For studied timberline conifers, seasonal changes in γ might be especially relevant in winter, when frost drought and freezing stress can lead to an excessive embolism.

Keywords: conifers, Picea abies, Pinus mugo, timberline

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