ABSTRACT Luminescent collectors have advantages over geometric concentrators in that tracking is ... more ABSTRACT Luminescent collectors have advantages over geometric concentrators in that tracking is unnecessary and both direct and diffuse radiation can be collected. However, development has been limited by the performance of luminescent dyes. We have recently proposed a novel concentrator in which the dyes are replaced by quantum dots (QDs). Advantages over dyes include that the absorption threshold can be tuned by choice of dot diameter, and that the red shift between absorption and luminescence is related to the spread of dot sizes. In this paper we discuss how we have developed a self-consistent thermodynamic model for planar concentrators which allows for re-absorption by the QDs. r 2002 Published by Elsevier Science B.V.
ABSTRACT Quantitative autoradiography was used to determine the location and density of beta 1- a... more ABSTRACT Quantitative autoradiography was used to determine the location and density of beta 1- and beta 2-adrenoceptors in the right atrium (RA), left ventricular free wall (LVFW), right ventricular free wall (RVFW), interventricular septum (IVS), right atrium from an area near the atrioventricular node (RAAV) and cardiac nerves (N) taken from a patient with end-stage cardiac failure. The densities of beta-adrenoceptors detected by the non-selective beta-adrenoceptor antagonist radioligand (-)-[125I] cyanopindolol (50pM) were 4.93 (N), 10.6 (RVFW), 12.2 (RA), 12.4 (IVS), 15.8 (LVFW) and 18.7 fmol (mg protein)-1 (RAAV). The proportion of beta 2-adrenoceptors ranged from 19.5% (RAAV) to 95% (N). RA taken from patients with ischaemic heart disease had a higher density of beta-adrenoceptors (29.3 fmol (mg protein)-1). The results suggest that both beta 1- and beta 2-adrenoceptors are down-regulated in patients with end-stage cardiac failure. Positive inotropic responses were established to (-)-isoprenaline, RO363 (beta 1-selective), procaterol (beta 2-selective) and dopexamine in the absence or presence of the antagonist CGP 20712A (beta 1-selective) or ICI 118,551 (beta 2-selective) in electrically driven human right atrial appendage strips. RO363 and procaterol were nearly full agonists in this preparation and produced their responses through activation of beta 1- or beta 2-adrenoceptors, while dopexamine was a partial agonist which produced its inotropic responses through activation of both receptor subtypes. These studies demonstrate the presence and location of beta 1- and beta 2-adrenoceptors in the human heart.
Perioperative spasm of the internal mammary artery (IMA) may occur after coronary artery bypass s... more Perioperative spasm of the internal mammary artery (IMA) may occur after coronary artery bypass surgery. To establish the most appropriate dilator agent, we tested the reactivity of ring segments of human IMA in organ baths to various constrictor and dilator agents. We found that the thromboxane mimetic U46619 was the most potent IMA constrictor agent, followed by norepinephrine, serotonin, phenylephrine, and potassium chloride (K+). In K+- or U46619-precontracted IMA, glyceryl trinitrate and papaverine caused full relaxation. In K+-precontracted arteries, nifedipine, verapamil, and diltiazem caused full relaxation, but nifedipine was 15-fold more potent than the other calcium antagonists. In contrast, pretreatment of vessels with glyceryl trinitrate failed to alter subsequent contraction to U46619 or K+ while nifedipine pretreatment abolished subsequent contraction to K+ and reduced sensitivity of the IMA to U46619. We conclude that perioperative IMA spasm could be treated with the rapid-onset, nonspecific, vasodilator glyceryl trinitrate, but for prophylaxis of IMA spasm, calcium antagonists or specific receptor antagonists should be tested in the clinical setting.
The molecular forms of ß-amylase present in developing, mature, germinating and malted grains of ... more The molecular forms of ß-amylase present in developing, mature, germinating and malted grains of barley (Hordeum vulgare L.), and in vegetative tissues, have been studied using Western-blot analyses and isoelectric focusing of isoenzymes. Five isoforms with different relative molecular masses (Mrs) could be recognised. The major isoform present in the mature grain, called isoform B, had an Mr of about
The use of bilateral internal thoracic arteries (BITAs) is associated with improved long-term sur... more The use of bilateral internal thoracic arteries (BITAs) is associated with improved long-term survival after coronary artery bypass grafting (CABG). However, it is unclear whether the addition of a radial artery (RA) in patients already receiving BITA confers any additional survival benefit over that of a saphenous vein (SV). As such, we reviewed our multicentre experience and compared both strategies. From 1995 to 2010, 1497 patients underwent primary isolated CABG for three-vessel coronary disease using BITAs. An SV was used as a third conduit in 460 (31%) patients and an RA in 1037 (69%). A total of 1258 distal anastomoses were performed using RAs and these were to the diagonal territory in 169, the circumflex in 454 and the right coronary in 635. Survival data were obtained using the National Death Index and propensity-score matching was used for risk-adjustment. The overall cohort was young (mean age 61 ± 9 years). Patients receiving RAs were more likely to be younger, and were less likely to have experienced a prior myocardial infarction. At 30 days, mortality was similar (BITA + SV: 5, 1.1% vs BITA + RA: 9, 0.9%, P = 0.77). At 15 years, BITA + RA patients experienced improved unadjusted survival (BITA + SV: 67 ± 4.6% vs BITA + RA: 82 ± 3.2%, P < 0.0001). Multivariable Cox regression in the entire cohort also showed the BITA + RA group to be associated with better survival (HR 0.58, 95% CI 0.44-0.75, P < 0.001). After propensity-score matching of 262 patient-pairs, BITA + RA experienced similar 30-day mortality (BITA + SV: 3, 1.1% vs BITA + RA: 3, 1.1%, P > 0.99). However, at 15 years, BITA + RA patients experienced improved risk-adjusted survival (BITA + SV: 72 ± 6.0% vs BITA + RA: 82 ± 5.2%, P = 0.021). The RA was associated with better risk-adjusted survival for grafting of the right coronary and its branches (148 matched pairs; SV-RCA: 74 ± 7.8% vs RA-RCA: 86 ± 6.5%, P = 0.0046 at 15 years). The addition of an RA graft even in patients already receiving BITAs is associated with a survival benefit. In younger patients with a reasonable long-term life expectancy, surgeons should strive to achieve total arterial revascularization with BITAs and radial arteries.
ABSTRACT Luminescent collectors have advantages over geometric concentrators in that tracking is ... more ABSTRACT Luminescent collectors have advantages over geometric concentrators in that tracking is unnecessary and both direct and diffuse radiation can be collected. However, development has been limited by the performance of luminescent dyes. We have recently proposed a novel concentrator in which the dyes are replaced by quantum dots (QDs). Advantages over dyes include that the absorption threshold can be tuned by choice of dot diameter, and that the red shift between absorption and luminescence is related to the spread of dot sizes. In this paper we discuss how we have developed a self-consistent thermodynamic model for planar concentrators which allows for re-absorption by the QDs. r 2002 Published by Elsevier Science B.V.
ABSTRACT Quantitative autoradiography was used to determine the location and density of beta 1- a... more ABSTRACT Quantitative autoradiography was used to determine the location and density of beta 1- and beta 2-adrenoceptors in the right atrium (RA), left ventricular free wall (LVFW), right ventricular free wall (RVFW), interventricular septum (IVS), right atrium from an area near the atrioventricular node (RAAV) and cardiac nerves (N) taken from a patient with end-stage cardiac failure. The densities of beta-adrenoceptors detected by the non-selective beta-adrenoceptor antagonist radioligand (-)-[125I] cyanopindolol (50pM) were 4.93 (N), 10.6 (RVFW), 12.2 (RA), 12.4 (IVS), 15.8 (LVFW) and 18.7 fmol (mg protein)-1 (RAAV). The proportion of beta 2-adrenoceptors ranged from 19.5% (RAAV) to 95% (N). RA taken from patients with ischaemic heart disease had a higher density of beta-adrenoceptors (29.3 fmol (mg protein)-1). The results suggest that both beta 1- and beta 2-adrenoceptors are down-regulated in patients with end-stage cardiac failure. Positive inotropic responses were established to (-)-isoprenaline, RO363 (beta 1-selective), procaterol (beta 2-selective) and dopexamine in the absence or presence of the antagonist CGP 20712A (beta 1-selective) or ICI 118,551 (beta 2-selective) in electrically driven human right atrial appendage strips. RO363 and procaterol were nearly full agonists in this preparation and produced their responses through activation of beta 1- or beta 2-adrenoceptors, while dopexamine was a partial agonist which produced its inotropic responses through activation of both receptor subtypes. These studies demonstrate the presence and location of beta 1- and beta 2-adrenoceptors in the human heart.
Perioperative spasm of the internal mammary artery (IMA) may occur after coronary artery bypass s... more Perioperative spasm of the internal mammary artery (IMA) may occur after coronary artery bypass surgery. To establish the most appropriate dilator agent, we tested the reactivity of ring segments of human IMA in organ baths to various constrictor and dilator agents. We found that the thromboxane mimetic U46619 was the most potent IMA constrictor agent, followed by norepinephrine, serotonin, phenylephrine, and potassium chloride (K+). In K+- or U46619-precontracted IMA, glyceryl trinitrate and papaverine caused full relaxation. In K+-precontracted arteries, nifedipine, verapamil, and diltiazem caused full relaxation, but nifedipine was 15-fold more potent than the other calcium antagonists. In contrast, pretreatment of vessels with glyceryl trinitrate failed to alter subsequent contraction to U46619 or K+ while nifedipine pretreatment abolished subsequent contraction to K+ and reduced sensitivity of the IMA to U46619. We conclude that perioperative IMA spasm could be treated with the rapid-onset, nonspecific, vasodilator glyceryl trinitrate, but for prophylaxis of IMA spasm, calcium antagonists or specific receptor antagonists should be tested in the clinical setting.
The molecular forms of ß-amylase present in developing, mature, germinating and malted grains of ... more The molecular forms of ß-amylase present in developing, mature, germinating and malted grains of barley (Hordeum vulgare L.), and in vegetative tissues, have been studied using Western-blot analyses and isoelectric focusing of isoenzymes. Five isoforms with different relative molecular masses (Mrs) could be recognised. The major isoform present in the mature grain, called isoform B, had an Mr of about
The use of bilateral internal thoracic arteries (BITAs) is associated with improved long-term sur... more The use of bilateral internal thoracic arteries (BITAs) is associated with improved long-term survival after coronary artery bypass grafting (CABG). However, it is unclear whether the addition of a radial artery (RA) in patients already receiving BITA confers any additional survival benefit over that of a saphenous vein (SV). As such, we reviewed our multicentre experience and compared both strategies. From 1995 to 2010, 1497 patients underwent primary isolated CABG for three-vessel coronary disease using BITAs. An SV was used as a third conduit in 460 (31%) patients and an RA in 1037 (69%). A total of 1258 distal anastomoses were performed using RAs and these were to the diagonal territory in 169, the circumflex in 454 and the right coronary in 635. Survival data were obtained using the National Death Index and propensity-score matching was used for risk-adjustment. The overall cohort was young (mean age 61 ± 9 years). Patients receiving RAs were more likely to be younger, and were less likely to have experienced a prior myocardial infarction. At 30 days, mortality was similar (BITA + SV: 5, 1.1% vs BITA + RA: 9, 0.9%, P = 0.77). At 15 years, BITA + RA patients experienced improved unadjusted survival (BITA + SV: 67 ± 4.6% vs BITA + RA: 82 ± 3.2%, P < 0.0001). Multivariable Cox regression in the entire cohort also showed the BITA + RA group to be associated with better survival (HR 0.58, 95% CI 0.44-0.75, P < 0.001). After propensity-score matching of 262 patient-pairs, BITA + RA experienced similar 30-day mortality (BITA + SV: 3, 1.1% vs BITA + RA: 3, 1.1%, P > 0.99). However, at 15 years, BITA + RA patients experienced improved risk-adjusted survival (BITA + SV: 72 ± 6.0% vs BITA + RA: 82 ± 5.2%, P = 0.021). The RA was associated with better risk-adjusted survival for grafting of the right coronary and its branches (148 matched pairs; SV-RCA: 74 ± 7.8% vs RA-RCA: 86 ± 6.5%, P = 0.0046 at 15 years). The addition of an RA graft even in patients already receiving BITAs is associated with a survival benefit. In younger patients with a reasonable long-term life expectancy, surgeons should strive to achieve total arterial revascularization with BITAs and radial arteries.
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Papers by Brian F Buxton