CALCIUM DIFFUSION WITH GADOLINIUM CONTRAST MEDIUM ON SYNAPSE SYSTEM USING MONTE CARLO SIMULATION

• Main Author: Sutresno, Adita
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/38315
• Institution: Institut Teknologi Bandung

Gadolinium is used by patients who will undergo diagnostics using MRI modalities as a prevalent contrast medium. One of the main advantages of using the gadolinium contrast medium is improving the quality of the image produced by MRI. The boundary between the sick and healthy parts can be seen more clearly by using a contrast medium. Patients who receive gadolinium injections are not enough once, and even many patients receive gadolinium injection repeatedly. Gadolinium has been injected into the patient's body does not all get out through the urinary system. Gadolinium left in the body can have a side effect that cannot ignore because of the toxic nature of gadolinium. One of the characteristics of gadolinium is as a barrier to calcium channels in the synapse. The presence of gadolinium interferes with the process of calcium diffusion, and signal transmission. This study aims to examine the process of calcium diffusion that occurs in the synapse and identify the factors that influence the process of calcium diffusion in the presence of gadolinium ions around synapse. This research was carried out in three stages from simple to complex. The conduct diffusion experiments in the compartment model and simulate the diffusion process was first with the goal was to observe and saw the diffusion process for a single injection. The second stage was to affect the diffusion process in the urinary system using the Monte Carlo method to obtain the amount of flux that passes through the diffusion channel. The third stage was simulating the diffusion process in synapse using the Monte Carlo method in the presence of gadolinium ions as a barrier ion against existing calcium channels. The involvement of gadolinium ions in the simulation was significant to be able to identify the effect of gadolinium ions on calcium flux into presynaptic. Besides, it also affects the number of neurotransmitters to synaptic cleft as a mechanism for transmitting signals to the nervous system. The first result was that the number of holes representing the calcium channel which was directly proportional to the number of ions moving from the first compartment to the second compartment. Decreasing the number of holes represents a calcium channel that begins to be covered by ions which were a barrier. The second result was a urinary system diffusion simulation shows that the change in concentration to twice the level of the first compartment causes an increase in the number of diffused ions to be four times when t0,5. The third result was a diffusion simulation on synapse which involves many quantities such as diffusion coefficient, the interaction between ions, area, and density of calcium channels to the effect of the presence of gadolinium barrier ions around synapse. The diffusion coefficient shows that each ion has different characteristics. The difference in diffusion coefficient influences the number of diffused ions, namely the more significant the diffusion coefficient of an ion, the higher the diffusion of ions. The large diffusion coefficient will show the number of ions which move more at the same time interval judging from the number of diffused ions at t0,25. The process of diffusion in synapse involving interactions between ions shows that the flux of ions was influenced by the size of the dissociation equilibrium constant. The size of the binding constant and the dissociation constant determines the magnitude of the balance constant. The smaller the dissociation equilibrium constant, the faster it takes to diffuse the ion. For the influence of the calcium channel area and density, it provides a linear relationship, namely the more full the calcium channel and the more calcium channels, the more diffused the number of ions. However, the density of the calcium channel at values above 2x104?m-2 was constant. The presence of barrier ions namely gadolinium around synapse has caused several things, namely the presence of gadolinium ions causing closure of calcium channels from a small, medium, and total closed level which depends on the number of gadolinium ions around synapse. The higher the gadolinium ions around synapse, the faster the calcium channel closure. This situation causes the number of calcium ions that can diffuse from the pre-synaptic outer region into pre-synaptic also to decrease due to the increasing number of calcium channels covered by gadolinium ions. The calcium ions can diffuse in pre-synaptic, it causes the number of synaptic vesicles that can anchor on the surface of the docking palce and release the neurotransmitter decreases. The chemical transmission process in synapse to be disrupted due to the reduction of the number of neurotransmitters and that can be released. Thus, the overall presences of gadolinium in synapse can a significant influence on the disruption of the chemical transmission (neurotransmitter) process that occurs in a synapse.