Time filter

Source Type

St. Petersburg, FL, United States

Serebrennikova Y.M.,University of South Florida | Patel J.,University of South Florida | Garcia-Rubio L.H.,Claro Scientific
Applied Optics | Year: 2010

The absorption and scattering properties of three developmental stages of protozoan parasite Plasmodium falciparum were studied both experimentally and theoretically. Experimentally, the light attenuation and forward scattering from parasites extracted from host erythrocyte cultures were measured with UV-visible spectroscopy. The measured spectra were interpreted theoretically with a model based on the core-shell Mie theory in terms of the structural and compositional characteristics of the protozoa. The model accurately reproduced the features of the measured spectra of all developmental stages. The results show that realistic quantitative estimates of the parasite size, nucleotide, and hemozoin contents can be derived from the UV-visible spectroscopy measurements. © 2010 Optical Society of America. Source

We measured ultraviolet/visible multiangle and multiwavelength spectra of normal blood sample and sickled blood sample. The resulting spectra show differences due to changes in red blood cell morphology and composition in sickled blood sample. © OSA 2012. Source

Nonoyama A.,University of South Florida | Garcia-Lopez A.,Los Alamos National Laboratory | Garcia-Rubio L.H.,Claro Scientific | Leparc G.F.,Florida Blood Services | Potter R.L.,University of South Florida
Biomedical Optics Express | Year: 2011

Multiwavelength UV-visible transmission spectrophotometry is a useful tool for the examination of micron-size particle suspensions in the context of particle size and chemical composition. This paper reports the reliability of this method to characterize the spectra of purified red blood cells both in their physiological state and with modified hemoglobin content. Previous studies have suggested the contribution of hypochromism on the particle spectra caused by the close electronic interaction of the encapsulated chromophores. Our research shows, however, that this perceived hypochromism can be accounted for by considering two important issues: the acceptance angle of the instrument and the combined scattering and absorption effect of light on the particles. In order to establish these ideas, spectral analysis was performed on purified and modified red cells where the latter was accomplished with a modified hypotonic shock protocol that altered the hemoglobin concentration within the cells. Moreover, the Mie theory was used to successfully simulate the spectral features and trends of the red cells. With this combination of experimental and theoretical exploration, definition of hypochromism has been extended to two subcategories. © 2011 Optical Society of America. Source

Serebrennikova Y.M.,Claro Scientific | Garcia-Rubio L.H.,Claro Scientific
Applied Optics | Year: 2010

The majority of cells and microorganisms have a nonspherical shape and complex structure that challenge the interpretation of their spectral features. To address this issue, two approximations to the coreshell Mie theory were proposed. These included the approximation of light extinction by an ellipsoid with representation of the extinction by an equivalent sphere and representation of the extinction by a population of ellipsoidal particles with those of two weighted particle orientations. These hypotheses were first tested through numerical interpretation of the theoretical extinction spectra of prolate nucleated ellipsoids mimicking biological cells generated with anomalous diffraction approximation used as a reference method. Theoretical cases of fixed and random particle orientations demonstrated excellent capabilities of the proposed approach to retrieve the size, shape, and composition parameters of the model particles. Second, the UVvisible spectra of Leishmania species, promastigotes, elongated cells with prominent nuclei, were interpreted. The retrieved estimates of the protozoa size, shape, nucleus size, and nucleotide composition were in agreement with the corresponding microscopy estimates and literature alues. Both theoretical tests and experimental results illustrated that the proposed approach can be successfully applied to estimate the structural and compositional parameters of cells from spectroscopic measurements. © 2010 Optical Society of America. Source

Serebrennikova Y.M.,University of South Florida | Serebrennikova Y.M.,Claro Scientific | Patel J.,University of South Florida | Milhous W.K.,University of South Florida | Garcia-Rubio L.H.,Claro Scientific
Journal of Theoretical Biology | Year: 2010

Spectroscopic analysis can provide valuable insights into morphological and biochemical cellular transformations caused by diseases. However, traditional spectroscopic methods and the corresponding spectral interpretation approaches have been challenged by the complexities of the cell shape, orientation, and internal structure. Here we present an elegant spectral interpretation model that enables accurate quantitative analysis of the UV-visible spectra of red blood cells (RBCs) parasitized by the lethal human malaria parasite, Plasmodium falciparum. The model is based on the modified Mie theory (MMT) approach that incorporates the effects of the nonsphericity and orientation and multilayered cell structure to account for complex composition of the infected RBCs (IRBCs). We determine the structure and composition of the IRBCs and address unresolved matters over the alterations induced by the intraerythrocytic development of P. falciparum. The results indicate deformation and swelling of the IRBCs during the trophozoite stage of P. falciparum that is followed by substantial shrinkage during the schizont stages. We determine that up to 90% depletion of hemoglobin from the RBC cytosol does not lead to a net loss of iron from the infected cells. We quantitatively follow the morphological changes in the parasites during the intraerythrocytic development by applying the interpretation model to the UV-visible spectroscopic measurements of the IRBCs. We expect this method of quantitative spectroscopic characterization of the diseased cells to have practical clinical utility for rapid diagnosis, therapeutic monitoring, and drug susceptibility testing. © 2010 Elsevier Ltd. Source

Discover hidden collaborations