All human lives start with pregnancy. A pathological pregnancy can be physically, mentally, and financially detrimental to newborns and families. Preterm labor and birth (PTB) is one of the most serious pathological conditions associated with pregnancy. PTB affects 10% of global births and is the leading cause of death in children under five years of age. Multiple etiologies are identified for causing PTB and three major reproductive tissues are involved: the uterus, the cervix, and the feto–maternal interface. Throughout pregnancy, these reproductive tissues change in response to various signals, a process called remodeling. Timely and appropriate remodeling of these tissues is needed for a healthy pregnancy. One central element of remodeling is a change in tissues’ mechanical properties, the focus of this work. This dissertation investigates the mechanical environment of pregnancy by characterizing the remodeling of three reproductive tissues of primates (humans and Rhesus macaque monkeys) and computationally simulating pregnancy physiology. I combine comprehensive mechanical testing with digital image correlation (DIC) to capture the material behavior of reproductive tissues, characterize the architecture of these tissues’ fiber networks by optical coherence tomography (OCT), implement a microstructurally-inspired constitutive mate- rial model, conduct inverse finite element analysis (IFEA) to quantify observed remodeling, and finally use finite element analysis (FEA) to simulate pregnancy anatomy and physiology. Results presented here demonstrate that the non-human primate (NHP) cervix, human uterus, and NHP feto–maternal interface all undergo remodeling during pregnancy and experience com- plex stress conditions. In general, the NHP cervix becomes softer and more extensible, with distinct stages. While the ground substance compressibility stays approximately the same throughout gestation, the fiber network steadily becomes more extensible, though rapidly becomes less stiff and more dispersed during the second trimester. The human uterus late in gestation is softer and more extensible compared to its NP state; most of its remodeling involves changes to fiber network extensibility and architecture. The NHP feto–maternal interface adhesion strength reaches a peak early in the third trimester. Lastly, I generated preliminary subject-specific finite element models of NHP by using a workflow developed for human data. By doing this, the complex stress and stretch conditions that reproductive tissues undergo during pregnancy can be visualized. Future work advancing our understanding of pregnancy and women’s health should include the characterization of the time-dependent properties of reproductive tissues, investigation of the relationship between quantitative ultrasound measurements and tissues’ mechanical properties, and improvements to the current FEA workflow.

Fat intra-body communication is a newly proven concept that is built on using human fat tissues as a communication channel for electromagnetic waves inside the body. This allows for two implanted external devices to connect through an intra-body closed-loop communication channel. This concept utilizes the fact that the fat tissues have low dielectric properties and are located between two tissue layers, skin and muscle, which have high dielectric permittivity and high loss tangent so that the signal propagates and confines with lower losses within the fat tissue. In this study, the eligibility of using monkey fat tissues as a communication channel for intra-body communication is being investigated. This comes as a first step in a long process of testing implementing medical devices, mainly prosthetic limbs, on non-human primates using fat-IBC at microwave frequencies. To be able to do that, an experimental characterization of ex-vivo monkey fat, skin, and muscle tissues to explore their dielectric properties compared to those of humans is being carried out. This study of the dielectric properties of monkey tissues is the first of its kind to be carried out on two samples of ex-vivo monkey tissues. Calf tissues have also been investigated in the study to get an insight on the potential differences between human and non-human body tissues in general before doing measurements on monkey tissues. For the measurements, an RF network analyzer and an open-ended coaxial probe method have been implemented. Phantoms that mimic the human tissues have been fabricated to be used as a reference point. The initial investigation demonstrates that calf fat tissues have much higher dielectric properties than human fat tissues. Monkey fat, muscle, and skin tissues showed many similarities to human tissues regarding their dielectric properties. This indicates that monkey tissues can be used for fat intra-body communication. Future numerical and analytical modeling of the monkey tissues needs to be conducted to confirm and strengthen this finding.

The normal aging process in humans is characterized by a number of hallmark changes including decreased white matter volume in the brain and accompanying cognitive decline. This is in contrast to neurodegenerative aging processes which involve acute pathology which results in neuronal cell death. Studying non-degenerative normal aging in humans can be difficult because of the high prevalence of neurodegenerative diseases in the population and other potentially confounding effects. Rhesus monkeys are an excellent model organism for the study of normal aging, as their aging process has been demonstrated to involve diminished white matter volume, but they do not suffer from neurodegenerative diseases such as Alzheimer's. In this study we seek to quantify levels of myelin degradation using confocal microscopy in regions of interest where it has been previously demonstrated that loss of white matter integrity results in lower levels of cognitive function across different treatment groups including aging monkeys, calorie restricted monkeys, and controls for calorie restricted monkeys. These areas include prefrontal white matter which is vital to executive function, the hippocampus which is integral to memory consolidation and the learning process, and finally the anterior, middle, and posterior cingulum bundle. The cingulum bundle contains a diverse variety of projections between cortical and subcortical regions, including but not limited to projections to and from the cingulate cortex which has been demonstrated to be vital for emotional processing, the limbic system, and a wide spectrum of other functions. We aim to quantify white matter degradation in these regions by using immunofluorescent tagging for healthy myelin basic protein (MBP) and degraded myelin basic protein (dMBP) and by measuring the colocalization between the two. For prefrontal white matter and hippocampus, we did not find significant differences in myelin degradation across treatment groups. In the cingulum bundle, however, we did find a significant effect of treatment on overall myelin damage throughout the bundle, and in particular we determined that there was a significant difference in colocalization in the anterior cingulum bundle between aging monkeys and control calorie restricted monkeys. Analysis of behavioral testing data yielded surprising results as we were unable to find a strong correlation between our measure for myelin degradation, and level of cognitive impairment. Our results indicate that there are likely differences in regional vulnerability to age related myelin damage across different white matter regions of the brain, however we would like to expand on this study to gain a more accurate understanding of how loss of white matter volume is distributed through the brain and the impact that has on cognitive outcomes.

Establishing baseline activity budgets for zoo-housed captive animals can be important in tracking behavior changes that may indicate medical or other concerns, as well as assessing overall welfare and the need for implementation of interventions such as increased amounts of enrichment. This study sought to calculate activity budgets for the current spider monkeys residing at the Central Florida Zoo, a father-daughter pair of Ateles geoffroyi. Having a baseline activity budget is also valuable because major changes in behavior may accompany the upcoming introduction of new individuals to this particular group of spider monkeys. BORIS behavior coding software was used to log behavior continuously over 58.3 hours of observation. The individuals in this zoo setting spent significantly more time stationary (resting or still and awake) and less time engaged in feeding behavior than wild spider monkeys. However, they spent as much or more of their time moving than Ateles species in natural settings. Temperature and exhibit renovation had minimal to no observed effects on activity budgets. Human presence usually has the effect of increasing activity and vigilance of animals while decreasing resting time, but on busier days at the zoo, one subject (a pet-reared male spider monkey) spent more time resting and less time moving than when there were fewer zoo visitors. No aggression was observed, but affiliative social behavior like allogrooming and embracing was observed infrequently. The study animals appeared to lack the bimodal pattern of activity (with activity peaking early and late in the day) common in wild spider monkeys, a finding that is consistent with activity budgets of other spider monkeys that are frequently exposed to humans. Time of day affected activity budgets to a small degree; the monkeys became more active later in the day and spent more time resting in the morning.

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