The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
D.j. Pepple - One of the best experts on this subject based on the ideXlab platform.
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Sildenafil Increases the p50 and Shifts the Oxygen-Hemoglobin Dissociation Curve to the Right
The journal of sexual medicine, 2015Co-Authors: Shantol Sastrice Ellis, D.j. PeppleAbstract:Abstract Introduction Sildenafil (Viagra®) is a selective phosphodiesterase type 5 (PDE5) inhibitor that block the breakdown of cyclic guanyl monophosphate (cGMP) leading to relaxation of the smooth muscles of the corpus cavernous and an increase in blood flow resulting in penile erection. It is hypothesized that sildenafil will increase the release of oxygen from erythrocytes and shift the oxygen–hemoglobin Curve to the right. Aim The aim of this study was to investigate the effect of varying doses of sildenafil on the p50 of the oxygen–hemoglobin Dissociation Curve in blood samples from eight (8) healthy adult male volunteers with normal hemoglobin HbAA. Method The hemox‐analyzer was used to generate the p50 and the oxygen–hemoglobin Dissociation Curves. Main Outcome Measures The effect of different doses of sildenafil on the p50 values and shift of the oxygen–hemoglobin Curve were the main outcome measures. Result Sildenafil caused a statistically significant increase in the p50 values and rightward shift of the oxygen–hemoglobin Dissociation Curve. Conclusion Sildenafil caused a dose‐dependent increase in the release of oxygen from the erythrocytes as shown by the increased p50 values and rightward shift of the oxygen–hemoglobin Dissociation Curve. Ellis SS and Pepple DJ. Sildenafil increases the p50 and shifts the oxygen–hemoglobin Dissociation Curve to the right. J Sex Med 2015;12:2229–2232.
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Effect of cilostazol on the p50 of the Oxygen-Hemoglobin Dissociation Curve.
The International journal of angiology : official publication of the International College of Angiology Inc, 2014Co-Authors: Marsha-lyn Mckoy, Kyomi Allen, Andrea A Richards, D.j. PeppleAbstract:Cilostazol is a drug used for the treatment of intermittent claudication caused by narrowing of the blood vessels and reduced oxygen supply, characterized by intense pain in the leg when walking. This study was designed to investigate the effect of cilostazol on the P50 of the oxygen hemoglobin Dissociation Curve. A total of eight healthy adult subjects were studied. Blood samples (0.5 mL) from each subject were mixed with 5, 10, and 20 μL of the 0.5 mg/mL stock solution of cilostazol to give concentrations of 10, 20, and 40 µg/mL equivalent to adult doses of 50, 100, and 200 mg, respectively. The control sample had no drug added. The oxygen hemoglobin Dissociation Curve of each sample was plotted and the P50 determined with a Hemox-Analyzer (TCS, Medical Products Division, Southampton, PA). The mean P50 for the control samples was 28.27 ± 0.43 mm Hg. The values of the samples exposed to 10, 20, and 40 µg/mL cilostozol were 29.63 ± 0.66, 30.15 ± 0.77, and 31.66 ± 0.62 mm Hg, respectively. There was a statistically significant difference (p
Gerald E. Adams - One of the best experts on this subject based on the ideXlab platform.
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31P MRS to monitor the induction of tumor hypoxia by the modification of the oxygen affinity of hemoglobin using BW 589C
International journal of radiation oncology biology physics, 1994Co-Authors: Radhika Kalra, J. C. M. Bremner, Pauline J. Wood, J. M. Sansom, C. J. R. Counsell, Ian J. Stratford, Gerald E. AdamsAbstract:Abstract Purpose: BW 589C induces severe tumor hypoxia by modifying the affinity of oxyhemoglobin, causing a left shift of the Oxygen-Hemoglobin Dissociation Curve. 31 P magnetic resonance spectra (MRS) was used to monitor the effects of BW 589C on tumor energy metabolism in three experimental tumor models. Methods and Materials: HT-29 colon xenograft, murine transplantable RIF-1 fibrosarcoma and KHT sarcoma were studied in unanesthetised mice. 31 P MR spectra were acquired on a 4.7 Tesla magnet before administering oral BW 589C (250 mg/kg) and after 3, 6, and 24 h. Samples of tail vein blood were then taken for 2,3 DPG levels for RIF-1 and HT-29 tumors. Results: Doubling of inorganic phosphorus (P i ) to total phosphorus was observed 5–6 h after BW 589C for all three tumor types. Although the left shift due to BW 589C persists at 24 h, the level of P i to total phosphorus returned to baseline with no significant difference from control values for the RIF-1 and HT-29 tumors. These results suggest that there was cellular metabolic adaptation to the reduction of oxygen delivery by BW 589C. This does not appear to involve 2,3 DPG as there was no significant alteration in tumor levels. The death of hypoxic cells may, also, have contributed to the recovery of Pi to total phosphorus. Conclusion: The efficacy of bioreductive drugs can be enhanced by increasing the severity of tumor hypoxia. 31 P MRS in conjunction with other techniques for assessing the intratumor environment could play an important role in planning cancer therapy.
Shantol Sastrice Ellis - One of the best experts on this subject based on the ideXlab platform.
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Sildenafil Increases the p50 and Shifts the Oxygen-Hemoglobin Dissociation Curve to the Right
The journal of sexual medicine, 2015Co-Authors: Shantol Sastrice Ellis, D.j. PeppleAbstract:Abstract Introduction Sildenafil (Viagra®) is a selective phosphodiesterase type 5 (PDE5) inhibitor that block the breakdown of cyclic guanyl monophosphate (cGMP) leading to relaxation of the smooth muscles of the corpus cavernous and an increase in blood flow resulting in penile erection. It is hypothesized that sildenafil will increase the release of oxygen from erythrocytes and shift the oxygen–hemoglobin Curve to the right. Aim The aim of this study was to investigate the effect of varying doses of sildenafil on the p50 of the oxygen–hemoglobin Dissociation Curve in blood samples from eight (8) healthy adult male volunteers with normal hemoglobin HbAA. Method The hemox‐analyzer was used to generate the p50 and the oxygen–hemoglobin Dissociation Curves. Main Outcome Measures The effect of different doses of sildenafil on the p50 values and shift of the oxygen–hemoglobin Curve were the main outcome measures. Result Sildenafil caused a statistically significant increase in the p50 values and rightward shift of the oxygen–hemoglobin Dissociation Curve. Conclusion Sildenafil caused a dose‐dependent increase in the release of oxygen from the erythrocytes as shown by the increased p50 values and rightward shift of the oxygen–hemoglobin Dissociation Curve. Ellis SS and Pepple DJ. Sildenafil increases the p50 and shifts the oxygen–hemoglobin Dissociation Curve to the right. J Sex Med 2015;12:2229–2232.
Radhika Kalra - One of the best experts on this subject based on the ideXlab platform.
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31P MRS to monitor the induction of tumor hypoxia by the modification of the oxygen affinity of hemoglobin using BW 589C
International journal of radiation oncology biology physics, 1994Co-Authors: Radhika Kalra, J. C. M. Bremner, Pauline J. Wood, J. M. Sansom, C. J. R. Counsell, Ian J. Stratford, Gerald E. AdamsAbstract:Abstract Purpose: BW 589C induces severe tumor hypoxia by modifying the affinity of oxyhemoglobin, causing a left shift of the Oxygen-Hemoglobin Dissociation Curve. 31 P magnetic resonance spectra (MRS) was used to monitor the effects of BW 589C on tumor energy metabolism in three experimental tumor models. Methods and Materials: HT-29 colon xenograft, murine transplantable RIF-1 fibrosarcoma and KHT sarcoma were studied in unanesthetised mice. 31 P MR spectra were acquired on a 4.7 Tesla magnet before administering oral BW 589C (250 mg/kg) and after 3, 6, and 24 h. Samples of tail vein blood were then taken for 2,3 DPG levels for RIF-1 and HT-29 tumors. Results: Doubling of inorganic phosphorus (P i ) to total phosphorus was observed 5–6 h after BW 589C for all three tumor types. Although the left shift due to BW 589C persists at 24 h, the level of P i to total phosphorus returned to baseline with no significant difference from control values for the RIF-1 and HT-29 tumors. These results suggest that there was cellular metabolic adaptation to the reduction of oxygen delivery by BW 589C. This does not appear to involve 2,3 DPG as there was no significant alteration in tumor levels. The death of hypoxic cells may, also, have contributed to the recovery of Pi to total phosphorus. Conclusion: The efficacy of bioreductive drugs can be enhanced by increasing the severity of tumor hypoxia. 31 P MRS in conjunction with other techniques for assessing the intratumor environment could play an important role in planning cancer therapy.
Daniel L. Farkas - One of the best experts on this subject based on the ideXlab platform.
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Near-simultaneous hemoglobin saturation and oxygen tension maps in mouse brain using an AOTF microscope.
Biophysical journal, 1997Co-Authors: Ross D. Shonat, Elliot S. Wachman, Wen-hua Niu, Alan P. Koretsky, Daniel L. FarkasAbstract:A newly developed microscope using acousto-optic tunable filters (AOTFs) was used to generate in vivo hemoglobin saturation (SO2) and oxygen tension (PO2) maps in the cerebral cortex of mice. SO2 maps were generated from the spectral analysis of reflected absorbance images collected at different wavelengths, and PO2 maps were generated from the phosphorescence lifetimes of an injected palladium-porphyrin compound using a frequency-domain measurement. As the inspiratory O2 was stepped from hypoxia (10% O2), through normoxia (21% O2), to hyperoxia (60% O2), measured SO2 and PO2 levels rose accordingly and predictably throughout. A plot of SO2 versus PO2 in different arterial and venous regions of the pial vessels conformed to the sigmoidal shape of the Oxygen-Hemoglobin Dissociation Curve, providing further validation of the two mapping procedures. The study demonstrates the versatility of the AOTF microscope for in vivo physiologic investigation, allowing for the generation of nearly simultaneous SO2 and PO2 maps in the cerebral cortex, and the frequency-domain detection of phosphorescence lifetimes. This class of study opens up exciting new possibilities for investigating the dynamics of hemoglobin and O2 binding during functional activation of neuronal tissues.
