Monitoring the physiological effects of biological mediators on vascular permeability is important for identifying potential targets for antivascular leak therapy. This therapy is relevant to treatments for pulmonary edema and other disorders. Current methods of quantifying vascular leak are in vitro and do not allow repeated measurement of the same animal. Using an in vivo diffuse reflectance optical method allows pharmacokinetic analysis of candidate antileak molecules. Here, vascular leak is assessed in mice and rats by using the Miles assay and introducing irritation both topically using mustard oil and intradermally using vascular endothelial growth factor (VEGF). The severity of the leak is assessed using broadband diffuse reflectance spectroscopy with a fiber reflectance probe. Postprocessing techniques are applied to extract an artificial quantitative metric of leak from reflectance spectra at vascular leak sites on the skin of the animal. This leak metric is calculated with respect to elapsed time from irritation in both mustard oil and VEGF treatments on mice and VEGF treatments on rats, showing a repeatable increase in leak metric with leak severity. Furthermore, effects of pressure on the leak metric are observed to have minimal effect on the reflectance spectra, while spatial positioning showed spatially nonuniform leak sites.
The ability to determine the age of a bruise of unknown age mechanism is important in matters of domestic and child
abuse and forensics. While physicians are asked to make clinical judgment on the age of a bruise using color and
tenderness, studies have shown that a physicians estimate is highly inaccurate and in cases no better than chance alone.
We present here the temporal progression of reflection spectrum collected from accidentally inflicted contusions in adult
and child study participants with a synopsis of the observed phenomena. Reflection spectra collected using a portable
fiber optic reflection spectrometer can track the increase in extravasated hemoglobin from trauma caused blood vessel
rupture and subsequent removal of this hemoglobin occurring concurrent with an increase in the absorption attributed to
the breakdown product bilirubin. We hypothesize that this time dependent pattern can be used to determine the age of an
unknown bruise in an individual provided rate constant information for the patient can be determined in a controlled
calibration bruise. Using reflection spectra to estimate bruise age can provide a rapid and noninvasive method to
improve the ability of physicians in dating the age of a contusion.
Anemia is a serious worldwide disorder affecting 2 billion people globally. While the only clinically accepted method
of diagnosis remains an invasive blood draw and laboratory analysis, numerous attempts have been made to measure
total blood hemoglobin noninvasively. Although the palpebral conjunctiva can be used as a poor qualitative indicator
of anemia, a quantitative analysis of the conjunctiva using visible diffuse reflectance spectroscopy can provide an
accurate and easy method of noninvasive measurement. Preliminary studies using a traditional grating based
spectrometer have shown this method of analysis to be effective and accurate at diagnosing anemia and are presented
here. An alternative device to collect diffuse reflectance spectroscopy based on tunable liquid crystal technology that is
comparatively inexpensive and compact is also presented. Deformed helix ferroelectric liquid crystals (DHFLC) can
be tuned fully across the visible spectrum and have a narrow bandwidth of reflection. A handheld microspectrometer
facilitates this technique becoming a clinically viable method of analysis and enables total hemoglobin to be measured
quickly, and without the need of a blood draw. The rapidity of this test can make total hemoglobin measurement a new
vital sign, increasingly important because of the concurrent appearance of anemia with numerous other disorders.
The palpebral conjunctiva is an attractive location to qualitatively examine for the presence of anemia; however, this method of diagnosis has not been shown to be accurate. A spectroscopic examination of the palpebral conjunctiva enables the use of a quantitative parameter as a basis for diagnoses. Visible range diffuse reflectance spectra from the palpebral conjunctiva are examined from 30 patients and hemoglobin levels are extracted from these signatures using both a partial least-squares (PLS) multivariate regression model and a discrete spectral region model. Hemoglobin concentration derived from both these models is compared to an in vitro measurement of hemoglobin. Root mean squared errors of cross validation for the two analytical methods are 0.67 g/dL and 1.07 g/dL, respectively. Conjunctival reflectance spectra coupled with a PLS analysis achieve an enhanced specificity and sensitivity for anemia diagnoses over reported observational studies using the palpebral conjunctiva and achieve improved accuracy to other reported methods of noninvasive hemoglobin measurement.
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