The Experts below are selected from a list of 1104 Experts worldwide ranked by ideXlab platform
Li Hua-feng - One of the best experts on this subject based on the ideXlab platform.
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Effects of pregnancy on blood/Gas and Tissue/Gas partition coefficients of fluorinated volatile anesthetics in rats
Chinese Journal of Anesthesiology, 2006Co-Authors: Li Hua-fengAbstract:Objective To determine blood/Gas and Tissue/Gas partition coefficients of sevoflurane, isoflurane and halothane and evaluate the effects of pregnancy on them. Methods Ten 18-22 day pregnant and 10 non-pregnant SD rats were killed under pentobarbital anesthesia. The Tissue specimens of heart, liver, kidney and brain were obtained and made into homogenates respectively. The blood/Gas and Tissue/Gas partition coefficients of sevoflurane, isoflurane and halothane were determined using a method of 2-stage headspace equilibration by Gas chromatography. Results Blood/Gas and brain/Gas partition coefficients were lower in pregnant group than in non-pregnant group (P0.05) ,but there were no significant differences in other Tissue/Gas partition coefficients of halothane between the two groups. There were also no significant differences in blood/Gas and Tissue/Gas partition coefficients of sevoflurane and isoflurane between the two groups. Conclusion Pregnancy decreases blood/Gas and brain/Gas partition coefficients of halothane whereas there were no significant differences in other Tissue/Gas partition coefficient of halothane between the two groups. Pregnancy does not affect blood/Gas and Tissue/Gas partition coefficients of sevoflurane and isoflurane.
Jacques Seylaz - One of the best experts on this subject based on the ideXlab platform.
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Basal forebrain control of cortical blood flow and Tissue Gases in conscious aged rats
Brain Research, 1994Co-Authors: Richard Sercombe, Pierre Lacombe, Eric T. Mackenzie, V. Springhetti, Jacques SeylazAbstract:Cholinergic projections from the basal forebrain are capable of influencing local cortical blood flow (CoBF). The effect of age on this influence was investigated by measuring CoBF and Tissue Gas partial pressures (PtO2, PtCO2) by mass spectrometry in conscious young adult (2–4 months) and aged (22–28 months) Fischer 344 rats. Electrical stimulation (50 μA) of the substantia innominata (SI) increased frontal (+100.9%) and parietal (+28.4%) CoBF in young rats, but the effects were less in aged rats (frontal, +48.6%, P < 0.05; parietal, +18.9%, difference N.S.). Frontal PtO2 was increased in young but not aged rats (P < 0.01.). During standard hypercapnia, changes in CoBF, PtO2 and PtCO2 did not differ between young and aged rats. Under physostigmine infusion (0.15 mg/kg/h, i.v.), the CoBF increases to SI stimulation were approximately doubled in both cortices, in young and aged rats, and PtO2 increases were also significantly greater. However, frontal PtO2 increases were significantly smaller in aged (+7.6%) than in young (32.7%) rats, as were frontal PtCO2 reductions. We conclude: (i) the influence of the SI on frontal CoBF and PtO2 is substantially reduced with age; (ii) although physostigmine treatment potentiates this influence in both groups, the beneficial effects are relatively limited for aged rats.
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Hypercapnia and stimulation of the substantia innominata increase rat frontal cortical blood flow by different cholinergic mechanisms.
Brain Research, 1991Co-Authors: François Dauphin, Pierre Lacombe, Richard Sercombe, Edith Hamel, Jacques SeylazAbstract:This study was designed to further investigate in the rat how the cerebrovascular response to excitation of the projections from the substantia innominata (SI) to the frontal cerebral cortex was mediated. Local cortical blood flow (CoBF) (by helium clearance) and Tissue Gas partial pressures (pO2, pCO2) (indices of energy metabolic activity) were measured in the frontal cortex in unanesthetized adult Fischer rats in response to electrical stimulation of the SI and, for comparison, in hypercapnic conditions. SI stimulation and hypercapnia increased CoBF to a similar extent (+92% and +106%, respectively). Differences between the changes in Tissue Gas partial pressures under hypercapnia and SI stimulation suggest that different patterns of flow-metabolism coupling prevail in the mechanisms underlying the two cerebrovascular responses. Cortical pCO2 increased under hypercapnia, but decreased during SI stimulation, indicating that a 'vascular' mechanism (i.e. independent of energy metabolism activation) is at least partly responsible for the flow increase in the latter condition. However, cortical pO2 rose more under hypercapnia than during SI stimulation, suggesting that oxygen consumption, and hence energy metabolism, was increased in the latter case. The ability of the acetylcholine esterase inhibitor physostigmine and the muscarinic receptor antagonist scopolamine to modulate the responses was quantified. In both experimental conditions, CoBF changes were potentiated by 0.15 mg/kg/h physostigmine (by factors of about 2). In contrast, 1 mg/kg scopolamine reduced by 65% the frontal CoBF response elicited by SI stimulation but was without effect on the response to hypercapnia. Thus, although a cholinergic mechanism may be implicated in both responses, activation of muscarinic receptors appears to occur when the stimulation originates from the SI but not from the hypercapnia.
Ken F. Linnau - One of the best experts on this subject based on the ideXlab platform.
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Scary Gas: pathways in the axial body for soft Tissue Gas dissection (part I)
Emergency Radiology, 2017Co-Authors: Claire K. Sandstrom, Sherif F. Osman, Ken F. LinnauAbstract:Gas is often encountered in abnormal locations in the torso, including within soft Tissue compartments, vessels, and bones. The clinical significance of this Gas ranges from incidental, benign, and self-limited to aggressive infection requiring immediate surgery. As a result of fascial interconnectivity and pressure differences between compartments, Gas can dissect distant from its source. Gas can easily dissect between spaces of the extrapleural thorax, subperitoneal abdomen, deep cervical spaces, and subcutaneous Tissues. The pleural and peritoneal cavities are normally isolated but may communicate with the other spaces in select situations. Dissection of Gas may cause confusion as to its origin, potentially delaying treatment or prompting unnecessary and/or distracting workup and therapies. The radiologist might be the first to suggest and identify a remote source of dissecting Gas when the clinical manifestation alone might be misleading. The purpose of this paper, the first in a three-part series on soft Tissue Gas, is to explore the various pathways by which Gas dissects through the superficial and deep compartments of the torso.
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Scary Gas: a spectrum of soft Tissue Gas encountered in the axial body (part II)
Emergency Radiology, 2017Co-Authors: Claire K. Sandstrom, Sherif F. Osman, Ken F. LinnauAbstract:Ectopic Gas in the mediastinum, subperitoneal abdomen, and superficial soft Tissues is concerning and can be seen in the setting of trauma, iatrogenic injuries, infection, and inflammation. It can spread along different dissection pathways and may present remotely from the involved organ as described in part one. Recognition of ectopic Gas on imaging and differentiating it from other causes of benign Gas is very important as these conditions associated with ectopic Gas can lead to rapid patient deterioration and usually require urgent surgery. In part two, the different causes of ectopic and benign Gas in the torso are reviewed as well as the imaging features that can help to narrow the differential diagnosis.
Claire K. Sandstrom - One of the best experts on this subject based on the ideXlab platform.
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Scary Gas: pathways in the axial body for soft Tissue Gas dissection (part I)
Emergency Radiology, 2017Co-Authors: Claire K. Sandstrom, Sherif F. Osman, Ken F. LinnauAbstract:Gas is often encountered in abnormal locations in the torso, including within soft Tissue compartments, vessels, and bones. The clinical significance of this Gas ranges from incidental, benign, and self-limited to aggressive infection requiring immediate surgery. As a result of fascial interconnectivity and pressure differences between compartments, Gas can dissect distant from its source. Gas can easily dissect between spaces of the extrapleural thorax, subperitoneal abdomen, deep cervical spaces, and subcutaneous Tissues. The pleural and peritoneal cavities are normally isolated but may communicate with the other spaces in select situations. Dissection of Gas may cause confusion as to its origin, potentially delaying treatment or prompting unnecessary and/or distracting workup and therapies. The radiologist might be the first to suggest and identify a remote source of dissecting Gas when the clinical manifestation alone might be misleading. The purpose of this paper, the first in a three-part series on soft Tissue Gas, is to explore the various pathways by which Gas dissects through the superficial and deep compartments of the torso.
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Scary Gas: a spectrum of soft Tissue Gas encountered in the axial body (part II)
Emergency Radiology, 2017Co-Authors: Claire K. Sandstrom, Sherif F. Osman, Ken F. LinnauAbstract:Ectopic Gas in the mediastinum, subperitoneal abdomen, and superficial soft Tissues is concerning and can be seen in the setting of trauma, iatrogenic injuries, infection, and inflammation. It can spread along different dissection pathways and may present remotely from the involved organ as described in part one. Recognition of ectopic Gas on imaging and differentiating it from other causes of benign Gas is very important as these conditions associated with ectopic Gas can lead to rapid patient deterioration and usually require urgent surgery. In part two, the different causes of ectopic and benign Gas in the torso are reviewed as well as the imaging features that can help to narrow the differential diagnosis.
Richard Sercombe - One of the best experts on this subject based on the ideXlab platform.
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Basal forebrain control of cortical blood flow and Tissue Gases in conscious aged rats
Brain Research, 1994Co-Authors: Richard Sercombe, Pierre Lacombe, Eric T. Mackenzie, V. Springhetti, Jacques SeylazAbstract:Cholinergic projections from the basal forebrain are capable of influencing local cortical blood flow (CoBF). The effect of age on this influence was investigated by measuring CoBF and Tissue Gas partial pressures (PtO2, PtCO2) by mass spectrometry in conscious young adult (2–4 months) and aged (22–28 months) Fischer 344 rats. Electrical stimulation (50 μA) of the substantia innominata (SI) increased frontal (+100.9%) and parietal (+28.4%) CoBF in young rats, but the effects were less in aged rats (frontal, +48.6%, P < 0.05; parietal, +18.9%, difference N.S.). Frontal PtO2 was increased in young but not aged rats (P < 0.01.). During standard hypercapnia, changes in CoBF, PtO2 and PtCO2 did not differ between young and aged rats. Under physostigmine infusion (0.15 mg/kg/h, i.v.), the CoBF increases to SI stimulation were approximately doubled in both cortices, in young and aged rats, and PtO2 increases were also significantly greater. However, frontal PtO2 increases were significantly smaller in aged (+7.6%) than in young (32.7%) rats, as were frontal PtCO2 reductions. We conclude: (i) the influence of the SI on frontal CoBF and PtO2 is substantially reduced with age; (ii) although physostigmine treatment potentiates this influence in both groups, the beneficial effects are relatively limited for aged rats.
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Hypercapnia and stimulation of the substantia innominata increase rat frontal cortical blood flow by different cholinergic mechanisms.
Brain Research, 1991Co-Authors: François Dauphin, Pierre Lacombe, Richard Sercombe, Edith Hamel, Jacques SeylazAbstract:This study was designed to further investigate in the rat how the cerebrovascular response to excitation of the projections from the substantia innominata (SI) to the frontal cerebral cortex was mediated. Local cortical blood flow (CoBF) (by helium clearance) and Tissue Gas partial pressures (pO2, pCO2) (indices of energy metabolic activity) were measured in the frontal cortex in unanesthetized adult Fischer rats in response to electrical stimulation of the SI and, for comparison, in hypercapnic conditions. SI stimulation and hypercapnia increased CoBF to a similar extent (+92% and +106%, respectively). Differences between the changes in Tissue Gas partial pressures under hypercapnia and SI stimulation suggest that different patterns of flow-metabolism coupling prevail in the mechanisms underlying the two cerebrovascular responses. Cortical pCO2 increased under hypercapnia, but decreased during SI stimulation, indicating that a 'vascular' mechanism (i.e. independent of energy metabolism activation) is at least partly responsible for the flow increase in the latter condition. However, cortical pO2 rose more under hypercapnia than during SI stimulation, suggesting that oxygen consumption, and hence energy metabolism, was increased in the latter case. The ability of the acetylcholine esterase inhibitor physostigmine and the muscarinic receptor antagonist scopolamine to modulate the responses was quantified. In both experimental conditions, CoBF changes were potentiated by 0.15 mg/kg/h physostigmine (by factors of about 2). In contrast, 1 mg/kg scopolamine reduced by 65% the frontal CoBF response elicited by SI stimulation but was without effect on the response to hypercapnia. Thus, although a cholinergic mechanism may be implicated in both responses, activation of muscarinic receptors appears to occur when the stimulation originates from the SI but not from the hypercapnia.
