The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
Roger J Zemp - One of the best experts on this subject based on the ideXlab platform.
-
in vivo functional optical resolution photoacoustic microscopy with stimulated raman scattering fiber laser source
Biomedical Optics Express, 2014Co-Authors: Parsin Hajireza, Alexander Forbrich, Roger J ZempAbstract:In this paper a multi-wavelength optical-resolution photoacoustic microscopy (OR-PAM) system using stimulated Raman scattering is demonstrated for both phantom and in vivo imaging. A 1-ns pulse width ytterbium-doped fiber laser is coupled into a single-mode polarization maintaining fiber. Discrete Raman-shifted wavelength peaks extending to nearly 800 nm are generated with pulse energies sufficient for OR-PAM imaging. Bandpass filters are used to select imaging wavelengths. A dual-mirror galvanometer system was used to scan the focused outputs across samples of carbon fiber networks, 200μm dye-filled tubes, and Swiss Webster Mouse ears. Photoacoustic signals were collected in transmission mode and used to create maximum amplitude projection C-scan images. Double dye experiments and in vivo oxygen saturation estimation confirmed functional imaging potential.
-
real time handheld optical resolution photoacoustic microscopy
Optics Express, 2011Co-Authors: Parsin Hajireza, Wei Shi, Roger J ZempAbstract:In this paper a new generation of optical-resolution photoacoustic microscopy (OR-PAM) with a wide range of potential clinical applications is demonstrated. Using fast scanning mirrors, an image guide with 30,000 fiber pixels, a refocusing lens and a unique probe we managed to reduce the footprint of an OR-PAM system from a stationary table-top system to a portable, 4cm by 6cm, probe weighing ~500g tethered to a scanning unit. The phantom studies show that the handheld optical-resolution photoacoustic microscope is able to image with ~7μm resolution. For in vivo studies images of the microvasculature in a Swiss Webster Mouse ear are shown. The compact, flexible nature of the proposed design and the small footprint of the apparatus increase the usability of OR-PAM for potential clinical applications such as in dermatology.
-
in vivo near realtime volumetric optical resolution photoacoustic microscopy using a high repetition rate nanosecond fiber laser
Optics Express, 2011Co-Authors: Wei Shi, Parsin Hajireza, Peng Shao, Alexander Forbrich, Roger J ZempAbstract:Optical-resolution photoacoustic microscopy (OR-PAM) is capable of achieving optical-absorption-contrast images with micron-scale spatial resolution. Previous OR-PAM systems have been frame-rate limited by mechanical scanning speeds and laser pulse repetition rate (PRR). We demonstrate OR-PAM imaging using a diode-pumped nanosecond-pulsed Ytterbium-doped 532-nm fiber laser with PRR up to 600 kHz. Combined with fast-scanning mirrors, our proposed system provides C-scan and 3D images with acquisition frame rate of 4 frames per second (fps) or higher, two orders of magnitude faster than previously published systems. High-contrast images of capillary-scale microvasculature in a live Swiss Webster Mouse ear with ~6-µm optical lateral spatial resolution are demonstrated.
Rhonda J Rosengren - One of the best experts on this subject based on the ideXlab platform.
-
curcumin modulates drug metabolizing enzymes in the female Swiss Webster Mouse
Life Sciences, 2006Co-Authors: Sophie P Valentine, Mette G Goodin, Martin Le Nedelec, Anna R Menzies, Marissa J Scandlyn, Rhonda J RosengrenAbstract:Curcumin, the yellow pigment found in turmeric, exhibits potent chemopreventative properties in both in vivo and in vitro cancer models. We hypothesized that this effect may occur via curcumin-mediated changes in enzymes involved in both carcinogen bioactivation and estrogen metabolism. Female Swiss Webster mice were treated with either curcumin (200 mg/kg or 400 mg/kg, p.o.) or vehicle control for 1 or 2 weeks. The results demonstrated that curcumin had no effect on the catalytic activities of ovarian aromatase, hepatic catechol-O-methyltransferase or hepatic UDP-glucuronosyltransferase. However, both doses of curcumin caused a 25% decrease in CYP1A catalytic activity, but not polypeptide levels, following 2 weeks of treatment. Additionally, following 2 weeks of curcumin at 400 mg/kg, there was a 20% decrease in the catalytic activity and a 28% decrease in polypeptide levels of CYP3A. While 2 weeks of curcumin treatment (400 mg/kg) caused a 20% increase in glutathione S-transferase activity, there was no parallel increase in hepatic stores of the co-factor glutathione. In conclusion small changes in CYP1A, CYP3A and GST following long term treatment (2 weeks) suggest that the combination of all three metabolic pathways may play a small role in curcumin's chemopreventative action.
-
epigallocatechin gallate modulates cyp450 isoforms in the female Swiss Webster Mouse
Toxicological Sciences, 2003Co-Authors: Mette G Goodin, Rhonda J RosengrenAbstract:This study was designed to determine the effect of the in vivo administration of epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) on enzymes involved in the synthesis and metabolism of estradiol. EGCG (12.5, 25, or 50 mg/kg/day, ip) or ECG (12.5 or 25 mg/kg/day, ip) was administered to female SwissWebster mice for 7 days. The chemicals were well tolerated by the mice with the exception of EGCG given at 50 mg/kg, which resulted in severe hepatic necrosis and a 67% mortality rate. Following the administration of nontoxic doses of EGCG and ECG, aromatase (CYP19), CYP3A, CYP1A, and catechol O-methyltransferase (COMT) were measured. Additionally, the activity of CYP2E1 was determined, since this CYP450 isoform is important in the bioactivation of numerous carcinogens. The results demonstrated that ovarian aromatase activity was inhibited 56% by EGCG (25 and 12.5 mg/kg), but not ECG, while hepatic CYP3A catalytic activity and polypeptide levels were increased 31 4 and 47 2%, respectively, by 25 mg/kg of EGCG. However, ECG (but not EGCG) inhibited CYP1A catalytic activity and polypeptide levels (31 5 and 47 5%, respectively). Hepatic and renal COMT, as well as renal CYP3A remained unchanged following catechin dosing. Hepatic CYP2E1 catalytic activity and polypeptide levels were significantly increased (37 3 and 22 3%) following administration of EGCG (25 mg/kg). These results indicate that EGCG modulates enzymes responsible for both the synthesis and metabolism of estradiol, which may provide a potential mechanism for the reported action of EGCG, reported action as an inhibitor of breast tumor growth.
-
methylphenidate inhibits cytochrome p450 in the Swiss Webster Mouse
Human & Experimental Toxicology, 2002Co-Authors: M Le J Nedelec, Rhonda J RosengrenAbstract:Drug interactions have previously been reported following the co-administration of methylphenidate (MPH) and drugs metabolized by the cytochrome P450 (CYP450) system such as imipramine. Therefore, this study used the Swiss Webster Mouse to determine the effect of MPH on CYP450 isozymes likely to be important in the interaction between MPH and imipramine. Single high doses of MPH (25, 50 and 100 mg/kg, i.p.) were administered to simulate the abuse of MPH. Under these conditions, MPH decreased total hepatic CYP450 to 50% of control. Additionally, MPH inhibited the catalytic activity of CYP1A and CYP2E1 by 50%, and decreased the polypeptide levels of CYP3A by 30%. In a second study designed to simulate more closely therapeutic use, MPH was administered orally for two weeks at 10-fold lower doses (2.5, 5 and 10 mg/kg/day). MPH decreased total hepatic CYP450 at both 5 and 10 mg/ kg/day (0.96 +/- 0.01 and 0.96 +/- 0.06 nmol/mg versus 1.34 +/- 0.01 nmol/mg for saline control, P<0.05). The catalytic activity and protein levels of CYP1A were diminished by up to 50% of control, while catalytic activity and polypeptide levels for CYP2E1 and CYP3A remained unchanged. These results indicate that MPH inhibits the CYP450 system following both abuse and therapeutic scenarios. However, this effect was dependent on both the isoform of CYP450 and the duration of MPH administration.
-
st john s wort extract induces cyp3a and cyp2e1 in the Swiss Webster Mouse
Toxicological Sciences, 2002Co-Authors: B J Bray, Nigel B Perry, David B Menkes, Rhonda J RosengrenAbstract:This investigation was designed to determine the ability of St. John's wort (SJW), a readily available antidepressant, to induce various hepatic drug metabolizing enzymes. SJW (140 or 280 mg/kg/day) was administered to male Swiss Webster mice for 1, 2, or 3 weeks. Enzymatic activity was analyzed in hepatic microsomes for all of the following drug metabolizing enzymes: CYP3A, CYP1A, CYP2E1, and UDP-glucuronosyltransferase (UDPGT). The catalytic activity of CYP1A was unchanged from control following any dose or duration of SJW, while both CYP3A and CYP2E1 catalytic activities were increased 2-fold by both SJW concentrations but only following 3 weeks of administration. Results from Western immunoblotting studies supported the changes in catalytic activity, as protein levels for CYP2E1 and CYP3A were increased (2.5-fold and 6-fold, respectively) following 3 weeks of SJW administration. Additionally, the catalytic activity of the conjugation enzyme UDPGT was unchanged from control following all SJW treatments. These results indicate that in the Mouse moderate doses of SJW cause an increase in the catalytic activity and polypeptide levels of CYP2E1 and CYP3A but only following 21 days of administration, while the catalytic activity of CYP1A and UDPGT activity remain unaffected.
-
short term treatment with st john s wort hypericin or hyperforin fails to induce cyp450 isoforms in the Swiss Webster Mouse
Life Sciences, 2002Co-Authors: B J Bray, Nerida J Brennan, Nigel B Perry, David B Menkes, Rhonda J RosengrenAbstract:Abstract This investigation was designed to determine whether St. John's wort (SJW)(435 mg/kg/d), a readily available antidepressant, or its purported active constituents hypericin (1 mg/kg/d) and hyperforin (10 mg/kg/d) were able to induce various hepatic cytochrome P450 (CYP450) isoforms. SJW, hypericin and hyperforin were administered to male Swiss Webster mice for four consecutive days and hepatic microsomes were prepared on day 5. None of the three treatments resulted in a statistical change in total hepatic CYP450 (SJW treated 0.95 ± 0.09 nmol/mg vs control 1.09 ± 0.14 nmol/mg). Furthermore, the catalytic activities of CYP1A2, CYP2E1 and CYP3A were unchanged from control following all three treatments as determined by ethoxyresorufin O-deethylation, p -nitrophenol hydroxylation and erythromycin N-demethylation respectively. Additionally, western immunoblotting demonstrated that there was no significant change in the polypeptide levels of any of the three isoforms. These results indicate that four days of treatment with moderate to high doses of SJW, hyperforin or hypericin fails to induce these CYP450 isoforms in the male Swiss Webster Mouse.
Parsin Hajireza - One of the best experts on this subject based on the ideXlab platform.
-
in vivo functional optical resolution photoacoustic microscopy with stimulated raman scattering fiber laser source
Biomedical Optics Express, 2014Co-Authors: Parsin Hajireza, Alexander Forbrich, Roger J ZempAbstract:In this paper a multi-wavelength optical-resolution photoacoustic microscopy (OR-PAM) system using stimulated Raman scattering is demonstrated for both phantom and in vivo imaging. A 1-ns pulse width ytterbium-doped fiber laser is coupled into a single-mode polarization maintaining fiber. Discrete Raman-shifted wavelength peaks extending to nearly 800 nm are generated with pulse energies sufficient for OR-PAM imaging. Bandpass filters are used to select imaging wavelengths. A dual-mirror galvanometer system was used to scan the focused outputs across samples of carbon fiber networks, 200μm dye-filled tubes, and Swiss Webster Mouse ears. Photoacoustic signals were collected in transmission mode and used to create maximum amplitude projection C-scan images. Double dye experiments and in vivo oxygen saturation estimation confirmed functional imaging potential.
-
real time handheld optical resolution photoacoustic microscopy
Optics Express, 2011Co-Authors: Parsin Hajireza, Wei Shi, Roger J ZempAbstract:In this paper a new generation of optical-resolution photoacoustic microscopy (OR-PAM) with a wide range of potential clinical applications is demonstrated. Using fast scanning mirrors, an image guide with 30,000 fiber pixels, a refocusing lens and a unique probe we managed to reduce the footprint of an OR-PAM system from a stationary table-top system to a portable, 4cm by 6cm, probe weighing ~500g tethered to a scanning unit. The phantom studies show that the handheld optical-resolution photoacoustic microscope is able to image with ~7μm resolution. For in vivo studies images of the microvasculature in a Swiss Webster Mouse ear are shown. The compact, flexible nature of the proposed design and the small footprint of the apparatus increase the usability of OR-PAM for potential clinical applications such as in dermatology.
-
in vivo near realtime volumetric optical resolution photoacoustic microscopy using a high repetition rate nanosecond fiber laser
Optics Express, 2011Co-Authors: Wei Shi, Parsin Hajireza, Peng Shao, Alexander Forbrich, Roger J ZempAbstract:Optical-resolution photoacoustic microscopy (OR-PAM) is capable of achieving optical-absorption-contrast images with micron-scale spatial resolution. Previous OR-PAM systems have been frame-rate limited by mechanical scanning speeds and laser pulse repetition rate (PRR). We demonstrate OR-PAM imaging using a diode-pumped nanosecond-pulsed Ytterbium-doped 532-nm fiber laser with PRR up to 600 kHz. Combined with fast-scanning mirrors, our proposed system provides C-scan and 3D images with acquisition frame rate of 4 frames per second (fps) or higher, two orders of magnitude faster than previously published systems. High-contrast images of capillary-scale microvasculature in a live Swiss Webster Mouse ear with ~6-µm optical lateral spatial resolution are demonstrated.
Raghubir P Sharma - One of the best experts on this subject based on the ideXlab platform.
-
modulation of p53 after maternal exposure to all trans retinoic acid in Swiss Webster Mouse fetuses
Experimental and Molecular Pathology, 2003Co-Authors: Suparna A Sarkar, Raghubir P SharmaAbstract:The response to exposure of all-trans-retinoic acid (RA) during development varies from physiologic to severe teratogenic outcomes and is dependent upon the dose and the stage of development in all species. Effects of RA-mediated teratogenesis may be due to its ability to cause apoptosis. We have recently reported the modulation of p53 in murine stem cells by RA. The aim of this study was to characterize the temporal and spatial pattern of p53 expression in Swiss Webster Mouse fetuses following maternal treatment with a single oral dose of 100 mg/kg body weight of RA during organogenesis. RA treatment resulted in a decreased p53 mRNA level in fetuses 24, 48, and 72 h after maternal treatment as detected by semiquantitative reverse transcriptase polymerase chain reaction. Western blot analysis showed a decrease in p53 protein at 24 and 48 h. Immunohistochemistry revealed decreased localization of p53 in the neuroepithelium of fetuses exposed to RA in utero. RA treatment also resulted in decreased nuclear p21 and decreased expression of cytosolic as well as nuclear p27 at 72 h in the fetuses. These results demonstrated that RA-mediated teratogenesis is accompanied by a reduction in the temporal and spatial pattern of p53 gene and protein expression in addition to the disruption of the cell cycle by modulation of p21 and p27.
-
expression of c myc and other apoptosis related genes in Swiss Webster Mouse fetuses after maternal exposure to all trans retinoic acid
Reproductive Toxicology, 2002Co-Authors: Suparna A Sarkar, Raghubir P SharmaAbstract:The Myc family of genes regulates proliferation, differentiation, and apoptosis. Temporal expression of Myc family genes and several pro-apoptotic genes were investigated during Swiss Webster mice organogenesis after maternal treatment with an oral dose of 100 mg/kg trans-retinoic acid (RA) or vehicle on day 10 post-coitum. Reverse transcriptase-polymerase chain reaction and ribonuclease protection assay revealed decreased c-myc expression at 48 h followed by an increase at 72 h in fetuses from RA-treated dams. Increased c-Myc protein was detected at 72 h in the RA-treated group. In utero RA-treatment resulted in decreased expression of max, mad, caspases, bax, and bad genes at 48 h. Terminal uridinetriphosphate nick end-labeling (TUNEL) analysis revealed increased apoptosis at 24-48 h, followed by decreased apoptosis 72 h after in utero RA-exposure, which correlated with the decreased expression of pro-apoptotic genes noted at 48 h. Further investigations are needed to understand the role of Myc family genes during RA-mediated teratogenesis.
Wei Shi - One of the best experts on this subject based on the ideXlab platform.
-
real time handheld optical resolution photoacoustic microscopy
Optics Express, 2011Co-Authors: Parsin Hajireza, Wei Shi, Roger J ZempAbstract:In this paper a new generation of optical-resolution photoacoustic microscopy (OR-PAM) with a wide range of potential clinical applications is demonstrated. Using fast scanning mirrors, an image guide with 30,000 fiber pixels, a refocusing lens and a unique probe we managed to reduce the footprint of an OR-PAM system from a stationary table-top system to a portable, 4cm by 6cm, probe weighing ~500g tethered to a scanning unit. The phantom studies show that the handheld optical-resolution photoacoustic microscope is able to image with ~7μm resolution. For in vivo studies images of the microvasculature in a Swiss Webster Mouse ear are shown. The compact, flexible nature of the proposed design and the small footprint of the apparatus increase the usability of OR-PAM for potential clinical applications such as in dermatology.
-
in vivo near realtime volumetric optical resolution photoacoustic microscopy using a high repetition rate nanosecond fiber laser
Optics Express, 2011Co-Authors: Wei Shi, Parsin Hajireza, Peng Shao, Alexander Forbrich, Roger J ZempAbstract:Optical-resolution photoacoustic microscopy (OR-PAM) is capable of achieving optical-absorption-contrast images with micron-scale spatial resolution. Previous OR-PAM systems have been frame-rate limited by mechanical scanning speeds and laser pulse repetition rate (PRR). We demonstrate OR-PAM imaging using a diode-pumped nanosecond-pulsed Ytterbium-doped 532-nm fiber laser with PRR up to 600 kHz. Combined with fast-scanning mirrors, our proposed system provides C-scan and 3D images with acquisition frame rate of 4 frames per second (fps) or higher, two orders of magnitude faster than previously published systems. High-contrast images of capillary-scale microvasculature in a live Swiss Webster Mouse ear with ~6-µm optical lateral spatial resolution are demonstrated.
