We discuss the design and performance of a miniature objective lens optimized for coherent Raman scattering microscopy. The packaged lens assembly has a numerical aperture of 0.51 in water and an outer diameter of 8 mm. The lens system exhibits minimum chromatic aberrations, and produces coherent Raman scattering images with sub-micrometer lateral resolution (0.648 μm) using near-infrared excitation pulses. We demonstrate that despite the small dimensions of the miniature objective, the performance of this lens system is comparable to standard microscope objective lenses, offering opportunities for miniaturizing coherent Raman scattering imaging probes without sacrificing the image quality.

LPL is the rate-limiting enzyme for uptake of TG-derived FFA in peripheral tissues, and the enzyme is expressed in the brain and CNS. We previously created a mouse which lacks neuronal LPL. This animal becomes obese on a standard chow, and we observed reduced lipid uptake in the hypothalamus at 3 months preceding obesity. In our present study, we replicated the animal phenotype in an immortalized mouse hypothalamic cell line (N41) to examine how LPL affects expression of AgRP as well as entry and storage of lipids into neurons. We show that LPL is able to modulate levels of the orexigenic peptide AgRP. LPL also exerts effects on lipid uptake into culture neurons, and that uptake of neutral lipid can be enhanced even by mutant LPL lacking catalytic activity. N41 cells also accumulate neutral lipid in droplets, and this is at least in part regulated by LPL. These data in addition to those published in mice with neuron-specific deletion of LPL suggest that neuronal LPL is an important regulator of lipid homeostasis in neurons and that alterations in LPL levels may have important effects on systemic metabolism and neuronal lipid biology.

OBJECTIVES/SPECIFIC AIMS: The specific objectives of this project are (1) identify, test, and validate the parameters for a simplified NLOM imaging probe that will provide specific research and point-of-care information on biofilm presence, therapeutic need and response of individual wounds to treatment. (2) Identify specific proteomic and metabolomic biomarkers of (i) wound susceptibility to infection, (ii) wound response to the most commonly used antibacterial measures in wounds, and (iii) establish criteria for more effective interventions. METHODS/STUDY POPULATION: First, optimal use parameters for NLOM including illumination, field of view, focal length, linear Versus concentric image acquisition, detection and filter wavelengths were identified. Parameters for evaluation included ease and speed of imaging, ability to map diagnostic criteria. Next, using the optimised NLOM imaging modality in bacterial biofilm isolates and subsequently a rabbit ear model of biofilm wound infection, proteomic and metabolomic biomarkers of susceptibility to infection were identified. The effects of 2 standard debridement and anti-infective treatments, polyvidone-iodine solution or cetrimide 15%+ chlorhexidine gluconate 1.5% were mapped in situ for up to 10 days using the NLOM probe. RESULTS/ANTICIPATED RESULTS: Using the novel custom NLOM probe, high resolution mapping of wound biofilm infection, as well as the underlying tissue was performed throughout the onset, development, treatment, and resolution of wound biofilm infection. Specific microbiological, microstructural, oxygenation, and pH parameters were mapped at defined surface and subsurface locations and time-points. Findings included the determination that some standard antimicrobial formulations provide a supportive environment for wound infection, and that micro-channels within the biofilm and their interface with the tissues serve as an important predictor and indicator of wound infection establishment, progression, and response. DISCUSSION/SIGNIFICANCE OF IMPACT: The novel multimodality in vivo NLOM imaging approach establishes an important tool for earlier and more specific diagnosis of wound infection risk, virulence, and invasiveness along with markers of successful treatment, and a simple clinical imaging tool for improving wound infection prevention and treatment.

Coherent Raman scattering (CRS) microscopy is gaining acceptance as a valuable addition to the imaging toolset of biological researchers. Optimal use of this label-free imaging technique benefits from a basic understanding of the physical principles and technical merits of the CRS microscope. This tutorial offers qualitative explanations of the principles behind CRS microscopy and provides information about the applicability of this nonlinear optical imaging approach for biological research.

Background and significance

There is a need to develop non-invasive diagnostic tools to achieve early and accurate detection of skin cancer in a non-surgical manner. In this study, we evaluate the capability of stimulated Raman scattering (SRS) microscopy, a potentially non-invasive optical imaging technique, for identifying the pathological features of s squamous cell carcinoma (SCC) tissue.

Study design

We studied ex vivo SCC and healthy skin tissues using SRS microscopy, and compared the SRS contrast with the contrast obtained in reflectance confocal microscopy (RCM) and standard histology.

Results and conclusion

SRS images obtained at the carbon-hydrogen stretching vibration at 2945 cm(-1) exhibit contrast related protein density that clearly delineates the cell nucleus from the cell cytoplasm. The morphological features of SCC tumor seen in the SRS images show excellent correlation with the diagnostic features identified by histological examination. Additionally, SRS exhibits enhanced cellular contrast in comparison to that seen in confocal microscopy. In conclusion, SRS represents an attractive approach for generating protein density maps with contrast that closely resembles histopathological contrast of SCC in human skin.