Hello Professor Kellar,

The cavitation bubble will expose HUVECs to mechanical deformation and stimulate G-protein coupled receptors on the cell membrane. Stimulation of the G-protein coupled receptor will lead to production of inositol triphosphate (IP3). IP3 is produced from the protein phospholipase C (PLC) cleaving phosphatidylinositol 4,5-biphosphate (PIP2). IP3 diffuses and binds to the IP3 receptor on the endoplasmic reticulum surface which then induces Ca++ release.

Thank you for your question.

Sincerely,
Justin

Hello Dr. Porter,
Structurally, type I collagen is known to be composed of fibrils which align in a parallel or antiparallel fashion to produce collagen fibers and lamellae. It has been observed through methods such as electron microscopy and second harmonic generation how the collagen lamellae orient themselves in three-dimensional space within the cornea, forming layers which run in different directions depending on the region within the cornea. Fibers of one lamella may interweave with adjacent lamellae, forming a pattern that is believed to provide structural support for the cornea as well as functional importance. However, although methods such as these can image the physical orientation of lamellae and the fibers within them, they are unable to provide information on the polarity of the molecules. Therefore, one can not distinguish between parallel and antiparallel fibers within lamellae. The sum frequency generation microscope that we use has the capability to resolve these structural questions through implementation of an interferometric setup providing phase-sensitive detection and enabling polarization studies. It is of interest to us whether more understanding of how the cornea functions can be obtained from studying the polarity orientations of fibers within lamellae, particularly those that participate in interweaving.
Thank you for your question.
Sincerely,
Julie

Hello Dr. Ludwick,

Cardiovascular studies are a very popular field within biophotonics. Fiber optic technologies allow for the delivery of light to many locations including the heart. Our group is actually actively studying cardiovascular plaques using Optical Coherence Tomography. We have built miniature fiber probes that can be inserted from the femoral artery and guided to lesions of interest for precise imaging. We can then measure different properties such as the elastic properties and wall thickness to better assess possibly plaque rupture. Multiphoton imaging can further improve upon these diagnostics as well by specifically targeting for molecular contrast such as lipids which form the interior of plaques. With these techniques, we can asses plaques at far higher resolutions and with higher specificity than compared to current techniques such as intravascular ultrasound.

Thank you for your question,

Joe

Hi Dr. Gannett,
Thanks for your question. We are in fact interested in monitoring stroke using our technology, and have published work pertaining to a preclinical rat model for stroke. Since most strokes are a result of ischemia, we can monitor this process in a similar fashion to how we monitor IRI shown in our presentation. In our stroke model, we perform an open vascular occlusion on the middle cerebral artery. Using SFDI, we can monitor light absorption and scattering in the rat brain. By interrogating the brain at several wavelengths of light, we are able to derive values for oxy/deoxy hemoglobin, from which we can quantify oxygen saturation, and thus tissue metabolism. In a similar manner to our kidney IRI study, we can also use light scattering changes to infer micro-scale changes such as cellular swelling and tissue edema.
Sincerely,
Kyle Nadeau

Hi Dr. Jakli,
When a sample is driven by waves of frequency w1 and w2, the molecules in the sample act like anharmonic oscillators, producing oscillations at frequency w1+w2. The induced dipole can be expressed as P(w1+w2)=X*E(w1)E(w2), X being the nonlinear susceptibility. For a centrosymmetric sample that has inversion symmetry, if the sample were driven by -E(w1) and -E(w2) instead, the induced dipole should be -P(w1+w2). However, the equation shows us that X-E(w1)*-E(w2) still produces P(w1+w2). In order for this to be true, X must be zero. Therefore, the sum frequency generation only exists for samples with non-centrosymmetry.
Thank you for your question.
Sincerely,
Julie