BEE 4530 - 2004 Student Papers

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https://hdl.handle.net/1813/114

Student research papers for Professor Ashim Datta's Biomed BEE 4530/Computer-aided Engineering course for 2004.

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Diffusion and Binding of Radio-Labeled Antibodies in a Tumor
Schweitzer, Andrew; Su, Wan-Lin; Benlifer, Adam; Mathrani, Vikram; Aarismaa, Linda (2004-07-13T14:18:01Z)
With the decreasing cost of monoclonal antibody production, radioimmunotherapy (RIT) has rapidly emerged as one of the more promising methods of treating cancer cells. RIT makes use of radio-labeled monoclonal antibodies to detect and deliver controlled doses of radiation to malignant cells. The primary advantage of this method is that damage to normal, healthy tissue is minimized. We investigated the use of radio-labeled antibodies as a method of tumor destruction. Our primary interests were the rate of antibody diffusion into the tumor, the antibody binding kinetics, and the overall effectiveness of radioimmunotherapy given the rate of radioactive decay. By modeling the concentration of bound antibody with respect to time, we were able to optimize tumor destruction while minimizing the damage to the surrounding tissue. Our results show that a computer simulation using FIDAP is a time-saving, cost-effective method of obtaining quantitative results about the binding kinetics of antibody to tumor. In addition, we determined that while the binding specificity plays an important role in ensuring proper binding to the tumor, the rate of antibody to antigen complex formation does not affect the treatment and that this process is limited by diffusion. Given this fact, we recommend that low molecular weight antibodies be used because they will typically have higher diffusivities. In an example case of metastatic melanoma, we found that 4.33 mg of 188Re-6D2 complex would destroy the tumor in our model.
A Cryosurgical Approach to Lung Cancer
Cabrera, Edgar Allen; Mullaney, Kerry; Ramirez, Marina (2004-07-13T14:10:46Z)
Lung cancer is the second leading cause of death in the United Statesi, presenting the need for more refined treatment options than traditional invasive surgery and chemo- and radiation therapy. This study investigates the use of less-invasive cryosurgery to effectively freeze and kill a cancerous lung tumor, 3mm in diameter, while minimizing peripheral tissue damage. A single, liquid-nitrogen filled probe is inserted into a lung tumor and maintained at a constant temperature of -190?C. The freezing front is monitored to ensure cancerous cell death and prevent excessive damage to the surrounding healthy tissue. Based on data obtained by analyzing probe temperature, contact time and model sensitivity to variations in biomaterial properties, recommendations are made for surgical implementation: an initial contact time of 6 minutes followed by successively shorter application times. Additionally, further study designs are discussed to improve the quality of this treatment method and to ensure target outcomes with respect to tumor cell death and protection of healthy lung tissue.
Ortho Evra: How Effective is the Patch in Women of Varying Weight
Kwiatkowski, Peter; Auerbach, Jon; Clouser, Brian; Di Iorio, Daniela; Minchoff, CJ (2004-07-13T14:07:37Z)
This study researched the birth control patch, Ortho Evra and the diffusivity of the hormones, ethinyl estradiol and norelogestromin, into the body through the epidermis. We modeled that all of the species that diffused through the epidermis was completely absorbed into the body. We found that our model validated the amounts given by Ortho Evra for drug release. However, many of the constraints and boundary conditions were taken from the Ortho Evra research information. Our study also analyzed the effectiveness of the hormone in women of varying weight, from 120 pounds to 198 pounds. Results indicated that the patch becomes less and less effective with increasing adipose tissue. This increase in adipose tissue results in a decreasing diffusivity value for the epidermis. Our study also researched the effects of incorrect usage of the Ortho Evra patch. We modeled the scenario of the patch falling off after a given time and the continued effectiveness of the drug. Our values imply that if the patch falls off the woman is not protected. The woman must restart the cycle in-order to reach steady state, which provides the needed amount of drug to be effective.
Protecting Orange Saplings from Irreparable Frost Damage
Buchlis, George; Koetje, Bethany; Kwon, Sang Yeon; Manos, Jamie; Rand, Gabriel (2004-07-13T14:01:44Z)
Nocturnal frost and freeze damage can have a major impact on the survival and fruit production of young citrus trees. When temperatures fall below -4oC irreparable damage occurs. Because of this damage, many methods, including insulating sapling trunks and building soil banks have been used to help reduce the rate at which these trees lose heat in sub-zero conditions. This study focused on the effect a combined insulation-and-metal-stake method has on preventing frost and freeze damage of Washington Navel Orange saplings by looking at increase in trunk temperature using this system and comparing it to trunk temperatures in both an insulation only system and a bare tree system. It was found that the rod had little effect on trunk warmth but trunk insulation helped significantly ? the thicker and denser the insulation, the better.
Heat Transfer in Laser Tumor Excision
Chen, Alan; Cheung, Edwin; Lee, Steven; Picuri, John; Shih, Tsung Li (2004-07-13T13:56:37Z)
Cancer is an ongoing disease that is present in a majority of the population. Laser surgery provides minimally invasive techniques to excise tumors in humans. This method allows quicker recoveries and fewer complications. This study analyzes the effectiveness of excision of tumor tissue using a CO2 laser. By using computer aided design and finite element analysis, we model a cylindrical tumor tissue with 0.3cm in diameter and height. A flux of 282mmW from the laser and a convection coefficient of KmmW???26105 were applied when designing this model. Our results produced temperature contour plots at several time intervals, all showing precise laser excision with minimal inadvertent tissue damage (less than 0.006 mm in depth after excising approximately 0.15 mm of tissue in depth). Sensitivity analysis indicate that changes in material properties such as conductivity, convection, specific heat, density, and laser power have minimal affects on the temperature profile.
Assessing the Effects of Icing the Body for 20 Minutes
Chin, Jonathan; Pham, Hubert; Steck, Alaina; Sterman, Sarah; Sun, Mindy (2004-07-13T13:51:42Z)
Icing is one of the most inexpensive and convenient treatments available to reduce inflammation in sore and injured muscles. A commonly purported icing regimen follows a ?20 minutes on, 20 minutes off? cycle, so we investigated how much skeletal muscle cools during the 20-minute icing period. To model the temperature distribution, we used an axisymmetric geometry consisting of five layers: the ice, a plastic bag, skin, subcutaneous fat, and muscle. Our initial results showed cooling of the most superficial muscle tissue by approximately 15oC. We found that changes in properties such as density, specific heat, and conductivity did not affect temperature contours at the 20-minute time point; however, heating via perfusion, which was initially neglected, had a substantial effect on the final results. When blood flow was introduced into the model, the temperature of superficial muscle decreased only 3.5oC. We thus conclude that although icing is an effective means of cooling superficial layers of muscle, it is not particularly efficacious at increasing depths.
A Study of the Role of Therapeutic Contact Lenses in Drug Delivery
Fung, Evonne Yuewai; Lee, Jennifer; Tong, Anita; Tran, Baotram; Yau, Yuk Yee (Amy) (2004-07-12T20:56:31Z)
Glaucoma is an optical condition caused by pressure build up in the eye and is the leading cause of blindness. Current methods to treat glaucoma include medicated eye drops and oral medication, which are both inefficient methods of administration. Most of the medication in eye drops does not reach the target tissue. In addition, when taken orally, much of the drug circulates in the bloodstream instead of reaching the eye. This is a potential problem since drugs used to treat glaucoma, such as timolol maleate, are also prescribed to elevate hypertension. To avoid possible side effects, researchers have developed a novel method of drug delivery that involves enclosing the drug in the contact lens to be worn directly over the eye. The drug-encapsulated contact lens can deliver the drug to the target tissue more effectively. This paper focuses on the drug delivery of the therapeutic contact lens in the treatment of glaucoma using a computer-simulated model created by FIDAP, a computational fluid dynamic software. The problem is modeled as mass transfer of timolol maleate over four layers (lens, tear, cornea, and aqueous humor) of an axis-symmetric cylindrical slab. Results show that with an initial concentration of 7 mg/g contact lens in the contact lens, the minimum effective concentration of 1.8 ?g/mL is achieved in the aqueous humor layer after 45 minutes. The contact lens continues to deliver the drug into the eye at above this concentration for another 75 minutes before dropping below the minimum effective concentration at 1.5 hours. Sensitivity analysis shows that cornea diffusivity is the most important parameter in the solution.
The Risks of LASIK Corrective Eye Surgery: A Mass Transfer Approach to a Universal Concern
Ferullo, Julia; Ruggles, Kelly; Lokchander, Bina; Siryk, Christina; Panda, Puneet (2004-06-17T21:25:34Z)
The laser vision correction procedure, LASIK, requires a thin flap of the cornea to be created by a microkeratome knife. The focus of this project was to study and quantify the moisture loss from the tiny corneal flap using the concepts of mass transfer. Significant (10 fold) moisture concentration differences between the bottom and top surface of the corneal flap were observed, in conjunction with a strong dependence on the diffusivity of the flap as well as the length of the procedure time. Outer edges of the flap suffered the most water loss. Amount of moisture loss (85% in two minutes) in addition to the location(s) of ?dry spots? were hypothesized to influence one of the few recurrent complications of LASIK, flap misalignment.
In Vitro Scaffold Construction for a Bio-artificial Liver
Webster, Brad; Jong Kim, Tak; Chow, Sharon; Wang, Jeff; Tsai, Chrissy (2004-06-17T21:22:03Z)
The main focus of this investigation is to design a scaffold that will accommodate a growing Bio-Artificial Liver (BAL) with oxygen. The two design objectives are to find the maximum length and the distance between the artificial capillaries of the scaffold to provide adequate oxygen supply above 1.98 x 10-19 g/um3 to prevent hypoxia to the growing liver tissues. By utilizing industrial modeling software, FIDAP and GAMBIT, a model of a single capillary with liver tissue attached directly was constructed to simulate the oxygen delivery by means of diffusion and convection from the capillary wall to the tissue and the uptake by metabolism. From the results obtained, it was concluded that diffusion, not convection of the oxygen flow within the capillary was the dominant process of oxygen transport throughout the tissue. The maximum distance traveled into the tissue with capillary length of 60 ?m was 147 ?m from the capillary at the inlet side of the tissue while diffusion at the outlet tissue was at a modest 108 ?m. These values are unacceptable for the feasible construction of oxygen transport system solely based on diffusion. Thus, this investigation concludes that novel methods of greater complexity are needed to construct a more efficient and economically applicable oxygen delivery system for the mass production of bio-organs.
Put Your Best Teeth Forward: A Mass Transfer Study of Crest Whitestrips
vinegar, abby; gaborski, pam; Bermudez, Claudia; Davis, Patty (2004-06-17T21:19:01Z)
Crest Whitestrips are thin, liquid films adhered to a plastic exterior that can be applied directly to the tooth, enabling mass transfer of its active ingredient, hydrogen peroxide, to penetrate the tooth outer layer. The tooth outer layer consists of enamel and dentin. The goal of this study was to model the concentration of hydrogen peroxide as it moves through the gel tooth outer layer for a period of 30 minutes. GAMBIT was used to create a two-dimensional mesh modeling the three layers through which the hydrogen peroxide diffuses through: the gel, enamel and dentin. FIDAP was then used to model the process in which hydrogen peroxide moved through these three layers. A sensitivity analysis was performed varying the diffusion coefficients and reaction rate of hydrogen peroxide being used up. It was found that accurate values for all of these properties must be obtained in order to determine an accurate solution.

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