The tetra-peptide sequence alanine-valine-proline-isoleucine (AVPI) is derived from a known inhibitor of apoptosis inhibitor proteins (IAPs) called Smac (second mitochondria-derived activator of caspases). Ala-Val-Pro-Ile can be further utilized as an anti-cancer agent by inhibiting the activities of apoptosis inhibitors so caspases can trigger apoptosis of cancer cells. AVPI, however, has poorly cell-penetration property thus limiting its ability to be utilized as a therapeutic agent for cancer treatments. We conjugated the AVPI molecule to a newly developed cell-penetrating peptide (CPP) called PepB to circumvent the situation of limited cellular availability. Solid Phase Peptide Synthesis (SPPS) methods have been utilized to prepared AVPI peptide derivatives. Key characterizations involve reverse-phase high-performance liquid chromatography (RP-HPLC), mass spectrometry, optical and fluorescence microscopy. / Bioengineering

Spinal cord injury has the potential to be debilitating, particularly in the pediatric population. Identification of the exact injury level can be difficult from conventional structural Magnetic Resonance Imaging (MRI) scans, and younger children often have difficulty in participating in the clinical examinations that define neurologic damage. Because of limitations of existing clinical examinations and conventional imaging, more advanced quantitative imaging techniques are important for improvement in diagnostic and prognostic evaluation of spinal cord injury. A quantitative characterization of the full spinal cord injury from both a functional and structural perspective has not been performed in pediatric subjects and has potential to provide important diagnostic and prognostic information. Diffusion tensor imaging (DTI) gives a non-invasive quantification of water diffusion in the spinal cord and can provide insight into white matter integrity, while high resolution volumetric imaging can determine cord cross sectional area reflecting atrophy occurring post injury. Multiple challenges exist in analysis of pediatric spinal cord data, including physiological motion, low signal-to-noise, thermal noise and image artifact, and cumbersome measurements of cord morphology. In this work, a complete pipeline for the acquisition and analysis of both functional DTI data and high resolution structural data is designed, tested, and implemented including MR image acquisition, motion correction, diffusion tensor estimation, region of interest analysis, and semi-automated cord cross sectional area measurement. Data for both healthy subjects and subjects with spinal cord injury is collected and significant correlations are shown between DTI and cord morphology metrics. This characterization of the injured spinal cord using both structural and functional data has the potential to offer important new information for examination of spinal cord injury. / Bioengineering

Regardless of the advances in orthopedic implants, implant longevity is still a limitation due to implant-related host responses to wear and the release of corrosion debris from metallic implants which are frequently used today. This has led to an increased incidence of repeated surgeries known as revision surgeries. Development in orthopedics is now geared towards biomaterials, specifically polymers, that can degrade, interact with the tissue and offer physiochemical cues to ensure cell processes that promote replication or restoration of the natural tissue function. Biodegradable polymers can eliminate stress shielding and can ensure the transfer of loading to the bone as they degrade for optimum bone healing by bone ingrowth. Polymers as load-bearing materials, on the other hand, face an important and unique challenge because they lack the mechanical stability of orthopedic metals. To enhance the mechanical properties of polymers intended for use in orthopedic applications, additives are incorporated into the polymeric matrix. In this work, we tested the feasibilities of three different additives: nanodiamond (ND) to improve the mechanical stability of the resulting composite, hydroxyapatite (HA) to improve the osteointegrative property of the material and nanosilver (NAg) for antibacterial property. Here, we describe the manufacturing procedures carried out to incorporate the additives into a PDLG-polymer matrix and various analytical methods to investigate the improvement due to the addition of the additives. Methods used were Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy/ Energy Dispersive X-ray (SEM/EDS), Three-point bending, Osteoblast cell culture, Mineralization, and Degradation study. From the results, PDLG/ND composites fabricated with 1wt% HA had a fairly even distribution of the additive in the polymeric matrix and showed the highest ultimate tensile strength, yield strength, young’s modulus. This concentration had the least decline in mechanical property after mineralization. Although elemental analysis showed an expected reduction in Ca ions, it had the most increase in P ions. Recommendations are made for future studies to reach a conclusive decision based on enhanced mineralization. / Bioengineering

Irregular wound healing, experienced by patients suffering from underlying pathology or reoccurring ulcers, is a major concern that often requires outside aid to induce proper healing. A potential therapeutic is KTTKS, a sub-fragment of the type I collagen pro-peptide which can facilitate extracellular matrix secretion from fibroblasts. Prior studies have shown that KTTKS can upregulate TGF-β and collagen deposition, which can facilitate faster cell migration into the wound bed and decrease overall wound closure time. However, the water-soluble nature of KTTKS decreases its bioactivity at the wound site. Attachment of a vinyl functional group to KTTKS allows conjugation into the backbone of a radically polymerizable hydrogel skin mimic. This formulation is hypothesized to increase the efficiency of KTTKS compared to existing configurations which contain non-immobilized peptides. / Bioengineering

No description available.

Solid stress, one of the physical hallmarks of cancer, is defined as the mechanical force generated and transmitted by the solid components of a tumor. Solid stress affects the trafficking and infiltration of immune cells, promotes metastasis and tumorigenic pathways, and impedes therapeutic delivery. Despite these clinical ramifications, questions remain regarding the origins and consequences of solid stresses. Answering these fundamental questions requires probing solid stresses at the cellular scale, where biological and immunological responses manifest, as well as in vivo, where the complexities of the tumor microenvironment exist. Here, we present the first in vivo, multi-scale optical measurements of solid stress in tumors using intravital imaging of deformable polyacrylamide hydrogel spheres embedded within primary tumors or in lung metastatic tumors through the hematogenous route. Our approach leverages multimodal intravital microscopy to obtain 3-D high-resolution spatial and longitudinal measurements of solid stresses in vivo. We measure and compare solid stresses (i) in primary vs metastatic tumors, (ii) in vivo vs in vitro settings, and (iii) at the single cell vs tissue scale. We compared the solid stresses in primary breast tumors vs breast cancer lung metastasis. We found that solid stresses are significantly higher in metastatic settings, although both metastatic and primary tumors were induced from the same cancer cells. Our results demonstrate the role of the microenvironment on solid stress genesis and potential implications on the differential treatment response between primary and metastatic settings. Furthermore, our method enables the comparison between the in vitro and in vivo models of solid stresses to evaluate how closely these in vitro models recapitulate the physical tumor microenvironment. While it has been shown through mathematical modeling that stress transmission is scale-dependent, we reveal for the first time experimentally that solid stress transmission is scale-dependent. Interestingly, we find that the stresses that individual tumor cells experience are a factor of 5–8 lower than the large stress levels measured at the tissue scales. This finding lays the groundwork for discovering novel biophysical mechanisms that cancer cells utilize to evade cell death from high mechanical stresses, and for establishing new therapeutic strategies aimed at increasing the vulnerability of cancer cells to mechanical stresses, resulting in cancer cell death. Furthermore, the dissertation delves into dispersion indices as a universal tool for quantifying biological images. Inspired by their use in measuring income distribution within human populations, dispersion indices are applied to the novel application of analyzing the distribution patterns of subcellular structures. This approach offers distinct advantages over traditional image analysis methods, especially in its ability to transcend the constraints imposed by developing separate tools for different biological systems. Dispersion indices are demonstrated to be effective in quantifying autophagic puncta, mitochondrial clustering, and microtubule dynamics. / 2026-05-23T00:00:00Z

Unforeseen off-target effects in clinical drug trials represent a growing expense in drug development. Biomimetic preclinical models that capture these off-target effects before human trials can maximally reduce these development costs, particularly for cardiotoxicity testing. As preclinical models, lab-grown organoids offer extremely high physiological accuracy yet exhibit high variance and complicated setup. To modulate cardiac organoid activities toward facilitating their development, this thesis developed induced-pluripotent stem cell cardiomyocyte (iPSC-CM) organoids and uses fiber optoacoustic emitters (FOEs) to photoacoustically stimulate cardiomyocyte organoids. As a platform for developing preclinical cardiac models, high-precision photoacoustic control offers a tunable, non-invasive system that offers insights into cell therapies and biomaterials to improve long-term patient outcomes.

Transcranial pulsed ultrasound noninvasively activates individual neurons and neural circuits in the brain, providing promise as a neuromodulation therapy. While ultrasound’s fundamental frequency and intensity influence neuromodulation efficacy, it is unclear whether temporal patterning contributes to its neural effect. Given that intrinsic neuronal activity is limited to a couple hundred hertz and often exhibits frequency preference, different subsets of neurons may respond to ultrasound delivered at pulse repetition frequencies (PRFs) in the physiologic range. In this dissertation, we use optical imaging techniques to capture cellular responses to 0.35 MHz ultrasound at multiple PRFs with high spatiotemporal precision in awake mice. First, we performed calcium imaging of individual motor cortex neurons, while delivering ultrasound at PRFs of 10, 40, or 140 Hz and compared these responses to the supra-physiologic PRF of 2 kHz. We next investigated cell type and PRF-specific effects of ultrasound pulsed at 10, 40, and 140 Hz using calcium imaging in transgenic mice with fluorescently tagged parvalbumin-positive interneurons. Most neurons were preferentially activated by only one of the three PRFs, highlighting unique cellular effects of physiologic PRFs. Finally, using voltage imaging we discovered that ultrasound induces prominent spiking and membrane depolarization with a latency shorter than 18 ms. Ultrasound also paced membrane voltage at the stimulation PRF, leading to prominent entrainment in many neurons. Together, these findings provide first direct experimental evidence that noninvasive ultrasound pulsed at physiologically relevant frequencies can selectively, reversibly, and directly activate neuronal subsets and entrain cellular dynamics, highlighting a novel strategy to engage and tune neural circuits for clinical applications. / 2025-05-23T00:00:00Z

The present thesis concerns theoretical studies of molecular interactions investigated by infrared and X-ray spectroscopic techniques, with emphasis on using these two techniques combined in pump-probe experiments. Four main types of studies are addressed: the use of near-edge X-ray absorption fine structure spectra (NEXAFS) to manifest through-bond and through-space interactions; the role of hydrogen bonding in the formation of X-ray photoelectron spectra as evidenced by simulations of the water dimer; the development of theory, with sample applications, for infrared X-ray pump-probe spectroscopy; and molecular dynamics simulations of light-induced fragmentation of water clusters. Ab initio calculations indicate that NEXAFS spectra give direct information about the through-bond and through-space interactions between vacant non-conjugated π* orbitals. It is found out that the X-ray photoelectron spectrum of the water dimer differs dramatically from the monomer spectrum in that two bands are observed, separated by the chemically shifted ionization potentials of the donor and the acceptor. The hydrogen bond is responsible for the anomalously strong broadening of these two bands. The studies show that X-ray core electron ionization of the water dimer driven by an infrared field is a proper technique to prove the proton transfered state contrary to conventional X-ray photoelectron spectroscopy. The physical aspects of the proposed new X-ray spectroscopic method - phase sensitive Infrared - X-Ray Pump-Probe Spectroscopy - are examined in detail using the wave packet technique in three applications; the NO molecule and the dynamics of proton transfer in core ionized water dimer and glyoxalmonoxime. It is found out that the phase of the infrared pump field strongly influences the trajectory of the nuclear wave packet on the ground state potential, which results in a phase dependence of the X-ray pump-probe spectra. A proper choice of the delay time of the X-ray pulse allows the direct observation of the X-ray transition in the proton transfered well of the core excited potential. It is found out that the glyoxalmonoxime molecule possesses an important feature; proton transfer accompanied by core hole hopping. Special attention is paid to the quantum control of the populations of vibrational level which is of crucial importance to shape the wave packet of desirable size. The wave packet technique becomes computationally very expensive when the number of nuclear degrees of freedom is large. Molecular dynamics is used instead in studies of light-induced nuclear kinetics in the water hexamer cluster. We predict a novel mechanism of the mechanical action of light on atoms and molecules. This mechanism is based on the rectification of the Lorentz force, which gives a unique opportunity of direct site selective mechanical action of light on atoms and molecules inside large systems like clusters or biomolecules. / <p>QC 20170222</p>

O objetivo da pesquisa foi o desenvolvimento de um abrangente Sistema de Circulação Extracorpórea usando o conceito integrado de segurança para equipamentos eletro-médicos. A necessidade inicial de determinação das especificações necessárias ao Sistema propiciou a definição de uma máquina coração-pulmão artificial ideal, com várias inovações e modificações. O projeto do Sistema de Circulação Extracorpórea considerando aspectos de funcionalidade, qualidade , confiabilidade e segurança, tanto do próprio aparelho como da instalação e do ambiente de paciente, conduziu ao estabelecimento de um modelo de concepção para equipamentos eletro-médicos, possibilitando inclusive a minimização dos problemas de manutenção e má utilização. A implementação e os ensaios realizados demonstraram a viabilidade do projeto e as dificuldades de desenvolvimento e construção de aparelhos para fins médicos. Estas dificuldades decorreram da inexistência de implementos e dispositivos produzidos em linhas normais de fabricação com as características exigidas pela aplicação médica. A exigência da definição precisa de diretrizes relativas à segurança de aparelhos eletro-médicos motivou uma reativação e aceleração ao processo normativo do setor. / The propose of the research was the development an Extracorporeal Circulation System using the integrated concept of electromedical equipment safety. The inicial need to determine the necessary specifications for the System lead to the definition of an ideal artificial heart-lung machine. Several novel ideas and concepts were developed. Modifications od accepted industry procedures were proposed. The design of the Extracorporeal Circulation System with the contraints of safety, quality, functionality and reliability lead to the development of a general model for the design of electromedical equipment. In the design process other issues were also considered, such as ease of maintenance, minimization of hazardous consequences due to equipment misuse or the existence of harsh environments. Finally, special needs required by the installation and the patient environment were pointed out. The implementation and testing of the machine confirmed the appropriateness of the design model that was developed. It also pointed to the difficulties in the development and full scale production of medical equipment. These difficulties were related to the lack of parts and devices produced locally with the required specifications for medical applications. A by-product of all these research and development activities was the renewal of much needed work on normalization of electromedical equipment in this country.