Browsing by Author "Ajayi, Tolulope O."

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    Analysis of Heart Rate Variability in Male and Female Rats
    (Office of the Vice Chancellor for Research, 2015-04-17) Ajayi, Tolulope O.; Santa Cruz Chavez, Grace; Schild, John H.
    Heart disease is the leading cause of death in the United States. Quantitative measures of cardiovascular function are often essential to effective clinical interventions. The QRS complex is one such measure widely used by cardiologists. These analyses can involve subtle changes in the magnitude and time course of the QRS complex, to differences in the timing between successive heart beats. Electrocardiograms (ECG) are continuous recordings of the QRS complex at various locations across the body surface and provide a comprehensive measurement of the electrical activity of the heart. Knowledge obtained from investigating ECG signal characteristics can help the cardiologist diagnose possible health or cardiac abnormalities such as arrhythmias and can provide objective measures of heart health following injury such as myocardial infarction. Heart rate variability (HRV) can also serve as a reliable indicator of heart health and has been shown to be a strong indicator of mortality and morbidity following myocardial infarction. Unfortunately, very little is known concerning the neurophysiological mechanisms underlying HRV beyond the broader impact of the autonomic nervous system and associated neurocirculatory reflexes. In this research project, we first implemented several established methods for quantifying HRV in male and female rats such as calculating the power spectral density of a long time series of HRV measures, and calculating the standard deviation of the averages of all beat-to-beat intervals in the recording. These measures compared well to those in the literature supporting the accuracy and reliability of the Matlab scripts created to process these data. Simultaneous recordings of the QRS complex and femoral arterial pressure (BP) provided the opportunity to determine how well BP recordings could be used to quantify HRV. In addition, HRV measurements were compared across populations of male and normal, cycling (OVI) and ovariectomized (OVX) female rats in order to determine if HRV is sexually dimorphic. Mentors: John H. Schild, Grace Santa Cruz Chavez, Department of Biomedical Engineering, Purdue School of Engineering and Technology, IUPUI, Indianapolis, IN
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    Modeling Pancreatic Cancer Tumor Microenvironment using a Microfluidics Culture System
    (Office of the Vice Chancellor for Research, 2016-04-08) Ajayi, Tolulope O.; Korc, Murray; Conteh, Abass
    Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths in the United States, with an overall five year survival rate of 7%. This is partly due to the lack of effective models that simulate the complex PDAC tumor microenvironment and allow for high throughput drug screening. Some of the key features of the PDAC tumor microenvironment are the presence of a dense stroma which impedes effective drug delivery to the pancreatic cancer cells (PCCs), as well as the presence of cancer associated fibroblasts (CAFs) that have been shown to modulate disease progression. The objective of this project is to develop an in vitro microfluidic cell culture system that allows researchers to recapitulate the PDAC tumor environment. The system, Tumor-Microenvironment-on-Chip (T-MOC) is manufactured using a replica molding technique. The chip consist of two polydimethylsiloxane (PDMS) layers separated by a porous membrane for gas exchange. This device forms an enclosed transparent device with input channel for cell entry and inner channels which mimic fluidic transport found in vivo. To analyze the potential of the device to simulate in vivo conditions, PCCs (GFP+) and CAFs (RFP+) were co-cultured with collagen and inserted into the device. Initial data analysis indicates that the device supports the growth of PCCs and allows formation of 3D tumor spheroids. In addition, analysis of GFP and RFP intensity demonstrated the effect of CAFs on PCCs growth, which diminished PCCs growth. This provides evidence that the microfluidic device can be used to replicate tumor environment allowing for future studies to screen potential drug candidates before in vivo studies.