Carolyn L. Bayer

Spectral photoacoustic imaging (sPAI) has the potential to detect clinically relevant measurements of blood oxygenation, non-invasively in real time. The unique advantage of sPAI is its ability to probe optical chromophores at extended imaging depths compared to purely optical modalities. PA imaging has previously been demonstrated using benchtop nanosecond pulsed solid-state lasers; however, their size and high cost limit the potential for clinical translation. Microfabricated pulsed laser diodes (PLDs) are miniaturized laser sources that can be fabricated and integrated at relatively low cost; however, microfabricated PLDs have been minimally investigated for the generation of photoacoustic signals due to the significantly lower energies they typically provide. In this work, we integrated an array of PLD diodes with optical excitation in the second near-infrared window, demonstrating deep imaging depths that exceed the imaging depths expected based on fluence alone. Using five PLDs integrated in series at a fluence of 61.5 µJ/cm ² , a maximum imaging depth of 4.26 cm was achieved with a detectable CNR in a porcine tissue phantom. Additionally, spectrally unmixed hemoglobin oxygenation measurements were accurate up to a depth of 3.11 cm with ∼10% accuracy. We validated device performance using an in vivo rat model, demonstrating a detectable SNR up to a depth of 4.13 cm and accurate tissue oxygenation assessment up to 3.85 cm from the kidney under layers of porcine tissue. Our device demonstrates the feasibility of microfabricated PLDs for clinically relevant photoacoustic imaging depths.

In this work, GPER (G protein-coupled estrogen receptor) was investigated as a novel therapeutic target for managing cardiovascular complications in preeclampsia. Activation of GPER by the selective agonist LNS8801 significantly improved cardiac function during pregnancy, with no effect on virgin animals, suggesting a pregnancy-specific impact. It also reduced blood pressure in pregnant Dahl SS/Jr rats with superimposed preeclampsia.

In vivo plant imaging is crucial for understanding plant biology and the influence of external factors on plant health. While exogenous contrast agents are widely used in animal bioimaging to enhance contrast, track flows, and provide molecular specificity, their application in plant tissue remains challenging and underexplored. Herein, we highlight the shortcomings of contrast agents in optical coherence tomography of plant tissue while demonstrating the successful use of Au bipyramids (AuBPs) as effective NIR-II contrast agents in photoacoustic imaging, enabling spatiotemporal flow tracking in live Buttercrunch lettuce over 5 days. Furthermore, rigorous plant health studies showed no adverse effects of the AuBPs on the physiological properties of Buttercrunch lettuce 7 days postinfiltration. The use of AuBPs as contrast agents in plant imaging, combined with the versatility of their surface chemistry, opens the possibilities for studies with molecular specificity.

Background Preeclampsia is a hypertensive disorder of pregnancy that affects multiple organs, including the heart, increasing long-term cardiovascular risks for both the mother and offspring. While the G protein-coupled estrogen receptor (GPER) has cardioprotective effects, its role in pregnancy-associated cardiac dysfunction, particularly in chronic hypertension, remains unclear, given the significant physiological adaptations that occur during pregnancy, including hormonal fluctuations and hemodynamic changes. This study investigated whether LNS8801, a selective and orally bioavailable GPER agonist, could improve cardiac function in virgin and pregnant Dahl salt-sensitive (SS/Jr) rats, a model of chronic hypertension exacerbated by pregnancy. Methods Female Dahl SS/Jr rats, both virgin and pregnant, were randomized into four groups: Virgin + Vehicle, Virgin + LNS8801, Pregnant + Vehicle, and Pregnant + LNS8801. LNS8801 (800 µg/kg/day, given orally) was administered in pregnant rats from gestational day (GD) 9 to 20 and for an equivalent period in virgin controls. Cardiac function was assessed via echocardiography, including speckle-tracking strain analysis and conventional systolic and diastolic parameters. Mean arterial pressure and proteinuria were also measured. Results LNS8801 significantly improved cardiac function in pregnant Dahl SS/Jr rats, enhancing global longitudinal, circumferential, and radial strain, as well as increasing systolic function. Additionally, LNS8801 enhanced diastolic function, improving left ventricular compliance (E/A ratio) and early mitral annular velocity (e′), while reducing left ventricular filling pressures (E/e′ ratio). In contrast, LNS8801 had no significant effects on cardiac function and blood pressure in virgin Dahl SS/Jr rats, suggesting that pregnancy-related adaptations may enhance GPER-mediated cardioprotection. LNS8801 treatment significantly reduced proteinuria in both virgin and pregnant rats, indicating a pregnancy-independent renal protective effect. Conclusion This study highlights the importance of pregnancy-specific adaptations in shaping the cardiovascular effects of GPER activation. While LNS8801 demonstrated cardioprotective and antihypertensive benefits in pregnant Dahl SS/Jr rats, its effects were absent in virgin animals, underscoring the influence of the physiological and hormonal environment on GPER-mediated responses. These findings provide a foundation for further exploration of GPER as a therapeutic target for pregnancy-associated cardiovascular dysfunction and preeclampsia, reinforcing the need for pregnancy-specific approaches in drug development.