Currently available laser surgery systems have less than ideal characteristics. For example, the ... more Currently available laser surgery systems have less than ideal characteristics. For example, the endoscopically deliverable argon and Nd:YAG lasers show charring and jagged cutting which limits their use in microsurgery and angioplasty. The CO2 laser shows relatively little charring in the pulsed mode but is not deliverable through flexible fiber optics. The excimer laser, while capable of clean cuts, has possible mutagenic and carcinogenic effects and problems in fiber delivery and adapting to a medical environment.
<b>Copyright information:</b>Taken from "Histological staining methods preparato... more <b>Copyright information:</b>Taken from "Histological staining methods preparatory to laser capture microdissection significantly affect the integrity of the cellular RNA"BMC Genomics 2006;7():97-97.Published online 27 Apr 2006PMCID:PMC1513394. Red shades correspond to higher expression in the staining group than A; green shades correspond to lower expression; and black indicates no difference.
Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Edition. CLEO '99. Conference on Lasers and Electro-Optics (IEEE Cat. No.99CH37013)
L'invention concerne un procede de retrait d'une cible a partir d'un echantillon biol... more L'invention concerne un procede de retrait d'une cible a partir d'un echantillon biologique, consistant a : fournir a un echantillon biologique monte sur un substrat un reactif qui agit de maniere selective sur la cible dans l'echantillon biologique, le reactif comprenant un agent qui absorbe la lumiere d'une longueur d'onde qui chauffe selectivement le reactif ; placer un film de transfert flexible ayant une surface inferieure et une surface superieure opposee de telle sorte que la surface inferieure du film de transfert soit adjacente a l'echantillon biologique ; appliquer un gradient de pression d'air uniforme sur le film de transfert flexible de facon a maintenir un contact thermique entre la surface inferieure du film de transfert et l'echantillon biologique ; exposer l'echantillon biologique a la lumiere de la longueur d'onde afin de chauffer selectivement le reactif et de produire un changement dans le film de transfert, ce qui perm...
Relations between different types of cameras used for retinal imaging were studied with the purpo... more Relations between different types of cameras used for retinal imaging were studied with the purpose of improving the quantitative precision of the imaging data (used for diagnostics and medical research). Based on the differences in visual quality and quantitative parameters, we designed analytical models of the effects that cameras introduce into the retinal data and described possible ways of digital post-processing. Some processing tasks involve detection and separation of features (such as the retinal microvessels) prior to subsequent analysis of underlying retinal pathology. Mathematical techniques for feature detection and inpainting are variational, implemented via numerically stable gradient descent schemes. Other tasks involve the estimates of translation - invariant sparse image coefficients allowing to separate the background and significant scales of the image from the texture-like auxiliary information. The above techniques are based on the recent work on the wavelet Gi...
Agerelated macular degeneration is a common disease that impairs central vision. To better unders... more Agerelated macular degeneration is a common disease that impairs central vision. To better understand early disease progression, we quantified two families of retinal chromophores: macular pigments in retinal axons and rod photoreceptor rhodopsin, whose changes have been associated with age-related maculopathy progression. First, we introduced noninvasive multispectral fluorescence imaging of the human retina and quantified macular pigments from those multispectral image sets. Second, we modeled the brightening of the lipofuscin autofluorescence in confocal scanning laser ophthalmoscopy imaging sequences to map local rod rhodopsin density.
Thousands of genes are expressed at such very low levels (≤1 copy per cell) that global gene expr... more Thousands of genes are expressed at such very low levels (≤1 copy per cell) that global gene expression analysis of rarer transcripts remains problematic. Ambiguity in identification of rarer transcripts creates considerable uncertainty in fundamental questions such as the total number of genes expressed in an organism and the biological significance of rarer transcripts. Knowing the distribution of the true number of genes expressed at each level and the corresponding gene expression level probability function (GELPF) could help resolve these uncertainties. We found that all observed large-scale gene expression data sets in yeast, mouse, and human cells follow a Pareto-like distribution model skewed by many low-abundance transcripts. A novel stochastic model of the gene expression process predicts the universality of the GELPF both across different cell types within a multicellular organism and across different organisms. This model allows us to predict the frequency distribution o...
American Journal of Physiology-Heart and Circulatory Physiology, 1990
With the technique of laser-Doppler velocimetry, cutaneous blood flows in the forearm of patients... more With the technique of laser-Doppler velocimetry, cutaneous blood flows in the forearm of patients with stable sickle cell disease after graded periods of proximal ischemia were compared with normal subjects matched for age, race, and sex, and with patients with anemia caused by beta(+)-thalassemia. In the sickle cell patients the reactive hyperemia was characterized by an increased time interval between the release of the occlusion and the peak amplitude response (time-to-peak) and by a greater period of blood flow above the base-line value (payback ratio) compared with controls. In addition, prolongation of the occlusion period led to an augmentation in the magnitude of the characteristic basal flow oscillations or an induction of this phenomenon at sites not exhibiting it before ischemia. Base-line or ischemia-provoked flow oscillations of either this magnitude or frequency were only observed in normal or thalassemic controls during brief intervals in the rapidly decaying portion ...
This paper presents our experience with intravascular ultrasound imaging of animal and human arte... more This paper presents our experience with intravascular ultrasound imaging of animal and human arteries in vitro and in vivo using a high-frequency (20 MHz) ultrasound transducer. In vitro, 32 human coronary artery segments were imaged with intravascular ultrasound and compared with corresponding histological sections. Ultrasound and histology measurements correlated significantly (P< 0-0001) for coronary artery cross-sectional area (r = 0-94), lumen cross-sectional area (r = 0-85) and wall thickness (r = 0-92). In vivo, 19 sheep and eight human common femoral arteries were imaged and the angiographic lumen diameter of 14 animal and six human arteries was compared to the diameter of the corresponding ultrasound images. Significant correlations were found for lumen diameter in animals and humans (P < 0001, r = 0-91 and P<00001, r = 0-96, respectively). These studies demonstrate that this technique can provide high resolution images of arterial vessels and may have unique advantages in diagnosing atherosclerotic vascular disease and in catheter based therapies.
American Journal of Physiology-Heart and Circulatory Physiology, 1999
Empirical data between 510 and 590 nm of diffuse reflected light from the pig heart in vivo have ... more Empirical data between 510 and 590 nm of diffuse reflected light from the pig heart in vivo have shown that myoglobin and cytochrome c absorption peaks with little apparent contribution of red blood cell (RBC) Hb. Monte Carlo simulations of photon migration in tissue were performed to compare the effects of myoglobin and cytochromes with those of blood Hb on photon pathlengths and diffuse reflectance of visible wavelengths (450–600 nm) from the pig heart in vivo. Wavelength dependence of the input parameters, including the transport-corrected scattering coefficients (1.1–1.2 mm−1) and the absorption coefficients of blood-free solubilized heart tissue (0.43–1.47 mm−1), as well as the absorption coefficients of Hb, were determined by an integrating sphere method and standard spectrophotometry, respectively. The Monte Carlo simulations indicate that in the 510- to 590-nm range the mean path length within the myocardium for diffusely reflected light varies from 1.4 to 1.2 mm, whereas th...
Journal of Clinical Laser Medicine & Surgery, 1991
Light delivery to anatomic areas involved by tumor is critical for effective photodynamic therapy... more Light delivery to anatomic areas involved by tumor is critical for effective photodynamic therapy. The authors provide a detailed overview of a light-diffusing device which they have used for intraoperative illumination of the peritoneal and pleural cavities in patients with tumors involving the surfaces of these cavities. Their device represents an inexpensive modification of widely available endotracheal tubes. It has been used to deliver intraoperative photodynamic therapy in over 50 patients without episodes of device failure. When combined with a lipid-based, light-diffusing medium and on-line power/energy density monitoring, it allows homogeneous illumination of these complex surfaces.
Laser capture microdissection (LCM) is a new method used to select and procure cell clusters from... more Laser capture microdissection (LCM) is a new method used to select and procure cell clusters from tissue sections. Once captured, the DNA, RNA or protein can be easily extracted from the isolated cells and analyzed by conventional PCR, reverse transcription (RT)-PCR or polyacrylamide gel electrophoresis, including protein zymography for specific macromolecular changes. In LCM, a thermoplastic polymer coating [ethylene vinyl acetate (EVA)] attached to a rigid support is placed in contact with a tissue section. The EVA polymer over microscopically selected cell clusters is precisely activated by a near-infrared laser pulse and then bonds to the targeted area. Removal of the EVA and its support from the tissue section procures the selected cell aggregates for molecular analysis. This initial NIH LCM approach using a flat transfer EVA film has been recently commercialized and has proven to be an effective routine microdissection technique for subsequent macromolecular analysis in many l...
This paper discusses a variational method of processing the scanning laser ophthalmoscope(cSLO) i... more This paper discusses a variational method of processing the scanning laser ophthalmoscope(cSLO) image sequences in the context of extracting the local rhodopsin density and modeling the bleaching kinetics. This work supports the characterization and detection of early pathological changes in clinical retinal data. Our goals include providing automated tools for tracing early pathological changes over time, in particular rhodopsin density variations and local lesion progression. Aside from helping to distinguish between healthy and possibly pathological regions, information about the bleaching parameters allows to separate and classify certain elements in the retinal image and may be utilized to refine the output of the edge-detection based method of the microvessel detection. Our computational approach is a variational technique that approximates measured cSLO image sets optimally within the range of the bleaching model. The characterizing parameters of the approximating curves are computed locally and their spatial changes reflect variations in bleaching kinetics and hence changes in the local rhodopsin density. We prove the consistency of the numerical results by showing that minimization of three different energy functionals measuring the deviation of the approximating curve from the original, leads to almost identical results despite the differences in the variational settings. We also show that the technique is naturally robust to noise. The curve fitting in the temporal direction of the image stack can be also viewed as a denoising/enhancement routine. The advantages of the temporal correction include a better fit of the image intensity function to the model and the avoidance of local averaging that would impair the spatial resolution.
Currently available laser surgery systems have less than ideal characteristics. For example, the ... more Currently available laser surgery systems have less than ideal characteristics. For example, the endoscopically deliverable argon and Nd:YAG lasers show charring and jagged cutting which limits their use in microsurgery and angioplasty. The CO2 laser shows relatively little charring in the pulsed mode but is not deliverable through flexible fiber optics. The excimer laser, while capable of clean cuts, has possible mutagenic and carcinogenic effects and problems in fiber delivery and adapting to a medical environment.
<b>Copyright information:</b>Taken from "Histological staining methods preparato... more <b>Copyright information:</b>Taken from "Histological staining methods preparatory to laser capture microdissection significantly affect the integrity of the cellular RNA"BMC Genomics 2006;7():97-97.Published online 27 Apr 2006PMCID:PMC1513394. Red shades correspond to higher expression in the staining group than A; green shades correspond to lower expression; and black indicates no difference.
Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Edition. CLEO '99. Conference on Lasers and Electro-Optics (IEEE Cat. No.99CH37013)
L'invention concerne un procede de retrait d'une cible a partir d'un echantillon biol... more L'invention concerne un procede de retrait d'une cible a partir d'un echantillon biologique, consistant a : fournir a un echantillon biologique monte sur un substrat un reactif qui agit de maniere selective sur la cible dans l'echantillon biologique, le reactif comprenant un agent qui absorbe la lumiere d'une longueur d'onde qui chauffe selectivement le reactif ; placer un film de transfert flexible ayant une surface inferieure et une surface superieure opposee de telle sorte que la surface inferieure du film de transfert soit adjacente a l'echantillon biologique ; appliquer un gradient de pression d'air uniforme sur le film de transfert flexible de facon a maintenir un contact thermique entre la surface inferieure du film de transfert et l'echantillon biologique ; exposer l'echantillon biologique a la lumiere de la longueur d'onde afin de chauffer selectivement le reactif et de produire un changement dans le film de transfert, ce qui perm...
Relations between different types of cameras used for retinal imaging were studied with the purpo... more Relations between different types of cameras used for retinal imaging were studied with the purpose of improving the quantitative precision of the imaging data (used for diagnostics and medical research). Based on the differences in visual quality and quantitative parameters, we designed analytical models of the effects that cameras introduce into the retinal data and described possible ways of digital post-processing. Some processing tasks involve detection and separation of features (such as the retinal microvessels) prior to subsequent analysis of underlying retinal pathology. Mathematical techniques for feature detection and inpainting are variational, implemented via numerically stable gradient descent schemes. Other tasks involve the estimates of translation - invariant sparse image coefficients allowing to separate the background and significant scales of the image from the texture-like auxiliary information. The above techniques are based on the recent work on the wavelet Gi...
Agerelated macular degeneration is a common disease that impairs central vision. To better unders... more Agerelated macular degeneration is a common disease that impairs central vision. To better understand early disease progression, we quantified two families of retinal chromophores: macular pigments in retinal axons and rod photoreceptor rhodopsin, whose changes have been associated with age-related maculopathy progression. First, we introduced noninvasive multispectral fluorescence imaging of the human retina and quantified macular pigments from those multispectral image sets. Second, we modeled the brightening of the lipofuscin autofluorescence in confocal scanning laser ophthalmoscopy imaging sequences to map local rod rhodopsin density.
Thousands of genes are expressed at such very low levels (≤1 copy per cell) that global gene expr... more Thousands of genes are expressed at such very low levels (≤1 copy per cell) that global gene expression analysis of rarer transcripts remains problematic. Ambiguity in identification of rarer transcripts creates considerable uncertainty in fundamental questions such as the total number of genes expressed in an organism and the biological significance of rarer transcripts. Knowing the distribution of the true number of genes expressed at each level and the corresponding gene expression level probability function (GELPF) could help resolve these uncertainties. We found that all observed large-scale gene expression data sets in yeast, mouse, and human cells follow a Pareto-like distribution model skewed by many low-abundance transcripts. A novel stochastic model of the gene expression process predicts the universality of the GELPF both across different cell types within a multicellular organism and across different organisms. This model allows us to predict the frequency distribution o...
American Journal of Physiology-Heart and Circulatory Physiology, 1990
With the technique of laser-Doppler velocimetry, cutaneous blood flows in the forearm of patients... more With the technique of laser-Doppler velocimetry, cutaneous blood flows in the forearm of patients with stable sickle cell disease after graded periods of proximal ischemia were compared with normal subjects matched for age, race, and sex, and with patients with anemia caused by beta(+)-thalassemia. In the sickle cell patients the reactive hyperemia was characterized by an increased time interval between the release of the occlusion and the peak amplitude response (time-to-peak) and by a greater period of blood flow above the base-line value (payback ratio) compared with controls. In addition, prolongation of the occlusion period led to an augmentation in the magnitude of the characteristic basal flow oscillations or an induction of this phenomenon at sites not exhibiting it before ischemia. Base-line or ischemia-provoked flow oscillations of either this magnitude or frequency were only observed in normal or thalassemic controls during brief intervals in the rapidly decaying portion ...
This paper presents our experience with intravascular ultrasound imaging of animal and human arte... more This paper presents our experience with intravascular ultrasound imaging of animal and human arteries in vitro and in vivo using a high-frequency (20 MHz) ultrasound transducer. In vitro, 32 human coronary artery segments were imaged with intravascular ultrasound and compared with corresponding histological sections. Ultrasound and histology measurements correlated significantly (P< 0-0001) for coronary artery cross-sectional area (r = 0-94), lumen cross-sectional area (r = 0-85) and wall thickness (r = 0-92). In vivo, 19 sheep and eight human common femoral arteries were imaged and the angiographic lumen diameter of 14 animal and six human arteries was compared to the diameter of the corresponding ultrasound images. Significant correlations were found for lumen diameter in animals and humans (P < 0001, r = 0-91 and P<00001, r = 0-96, respectively). These studies demonstrate that this technique can provide high resolution images of arterial vessels and may have unique advantages in diagnosing atherosclerotic vascular disease and in catheter based therapies.
American Journal of Physiology-Heart and Circulatory Physiology, 1999
Empirical data between 510 and 590 nm of diffuse reflected light from the pig heart in vivo have ... more Empirical data between 510 and 590 nm of diffuse reflected light from the pig heart in vivo have shown that myoglobin and cytochrome c absorption peaks with little apparent contribution of red blood cell (RBC) Hb. Monte Carlo simulations of photon migration in tissue were performed to compare the effects of myoglobin and cytochromes with those of blood Hb on photon pathlengths and diffuse reflectance of visible wavelengths (450–600 nm) from the pig heart in vivo. Wavelength dependence of the input parameters, including the transport-corrected scattering coefficients (1.1–1.2 mm−1) and the absorption coefficients of blood-free solubilized heart tissue (0.43–1.47 mm−1), as well as the absorption coefficients of Hb, were determined by an integrating sphere method and standard spectrophotometry, respectively. The Monte Carlo simulations indicate that in the 510- to 590-nm range the mean path length within the myocardium for diffusely reflected light varies from 1.4 to 1.2 mm, whereas th...
Journal of Clinical Laser Medicine & Surgery, 1991
Light delivery to anatomic areas involved by tumor is critical for effective photodynamic therapy... more Light delivery to anatomic areas involved by tumor is critical for effective photodynamic therapy. The authors provide a detailed overview of a light-diffusing device which they have used for intraoperative illumination of the peritoneal and pleural cavities in patients with tumors involving the surfaces of these cavities. Their device represents an inexpensive modification of widely available endotracheal tubes. It has been used to deliver intraoperative photodynamic therapy in over 50 patients without episodes of device failure. When combined with a lipid-based, light-diffusing medium and on-line power/energy density monitoring, it allows homogeneous illumination of these complex surfaces.
Laser capture microdissection (LCM) is a new method used to select and procure cell clusters from... more Laser capture microdissection (LCM) is a new method used to select and procure cell clusters from tissue sections. Once captured, the DNA, RNA or protein can be easily extracted from the isolated cells and analyzed by conventional PCR, reverse transcription (RT)-PCR or polyacrylamide gel electrophoresis, including protein zymography for specific macromolecular changes. In LCM, a thermoplastic polymer coating [ethylene vinyl acetate (EVA)] attached to a rigid support is placed in contact with a tissue section. The EVA polymer over microscopically selected cell clusters is precisely activated by a near-infrared laser pulse and then bonds to the targeted area. Removal of the EVA and its support from the tissue section procures the selected cell aggregates for molecular analysis. This initial NIH LCM approach using a flat transfer EVA film has been recently commercialized and has proven to be an effective routine microdissection technique for subsequent macromolecular analysis in many l...
This paper discusses a variational method of processing the scanning laser ophthalmoscope(cSLO) i... more This paper discusses a variational method of processing the scanning laser ophthalmoscope(cSLO) image sequences in the context of extracting the local rhodopsin density and modeling the bleaching kinetics. This work supports the characterization and detection of early pathological changes in clinical retinal data. Our goals include providing automated tools for tracing early pathological changes over time, in particular rhodopsin density variations and local lesion progression. Aside from helping to distinguish between healthy and possibly pathological regions, information about the bleaching parameters allows to separate and classify certain elements in the retinal image and may be utilized to refine the output of the edge-detection based method of the microvessel detection. Our computational approach is a variational technique that approximates measured cSLO image sets optimally within the range of the bleaching model. The characterizing parameters of the approximating curves are computed locally and their spatial changes reflect variations in bleaching kinetics and hence changes in the local rhodopsin density. We prove the consistency of the numerical results by showing that minimization of three different energy functionals measuring the deviation of the approximating curve from the original, leads to almost identical results despite the differences in the variational settings. We also show that the technique is naturally robust to noise. The curve fitting in the temporal direction of the image stack can be also viewed as a denoising/enhancement routine. The advantages of the temporal correction include a better fit of the image intensity function to the model and the avoidance of local averaging that would impair the spatial resolution.
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Papers by Robert Bonner