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Academic literature on the topic 'Microsphere infusion'

Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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Journal articles on the topic "Microsphere infusion"

1

Carter, A. M., J. R. G. Challis, and P. Svendsen. "Regional adrenal blood flow responses to adrenocorticotropic hormone after chronic embolization of the fetal placental circulation in sheep." Journal of Endocrinology 148, no. 3 (March 1996): 517–22. http://dx.doi.org/10.1677/joe.0.1480517.

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Abstract To ascertain whether repeated hypoxic stress would alter the response of the adrenal cortex to adrenocorticotropic hormone (ACTH), by premature activation of the hypothalamic–pituitary–adrenal axis, we studied fetal sheep subjected to daily reduction of arterial oxygen content by embolization of the fetal placental circulation with 15 μm microspheres for 8 days from about day 124 of gestation (term ∼147 days) and sham-embolized controls. Starting before the final embolization (or shamembolization) on day 8, and continuing for 24 h, the fetus was given an intravenous infusion of ACTH1–24 (0·5 μg/h) or vehicle. Fetal and maternal blood samples were taken for determination of immunoreactive cortisol, and regional adrenal and fetal placental blood flows were measured by the microsphere technique at three time points: 1 h before infusion, 3 h after the start of the infusion (1 h after embolization), and after 24 h of infusion. Prior to infusion of ACTH or vehicle, fetal placental blood flow was lower in microsphere-embolized fetuses than in sham-embolized controls (199 ± 15 vs 292 ± 25 ml/min per 100 g tissue; mean ± s.e.; P<0·01). However, plasma cortisol and adrenal cortical blood flow did not differ between embolized fetuses and controls. Adrenal vascular responses to the 24-h infusion of ACTH were similar in embolized and shamembolized fetuses. Adrenal cortical blood flow increased 3-fold (P<0·05) due to decreased vascular resistance (P<0·01), with no change in adrenal medullary blood flow. Thus, while daily embolization of the fetal placental circulation caused a sustained decrease in cotyledonary blood flow, no evidence of altered responsiveness of the adrenal cortex to ACTH was found in these experiments. Journal of Endocrinology (1996) 148, 517–522
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Pearse, David B., Thomas E. Dahms, and Elizabeth M. Wagner. "Microsphere-induced bronchial artery vasodilation: role of adenosine, prostacyclin, and nitric oxide." American Journal of Physiology-Heart and Circulatory Physiology 274, no. 3 (March 1, 1998): H760—H768. http://dx.doi.org/10.1152/ajpheart.1998.274.3.h760.

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We previously found that injection of 15-μm microspheres into the bronchial artery of sheep decreased bronchial artery resistance. This effect was inhibited partially by indomethacin or 8-phenyltheophylline, suggesting that microspheres caused release of a dilating prostaglandin and adenosine. To identify the prostaglandin and confirm adenosine release, we perfused the bronchial artery in anesthetized sheep. In 12 sheep, bronchial artery blood samples were obtained before and after the infusion of 1 × 106microspheres or microsphere diluent into the bronchial artery. Microspheres, but not diluent, decreased bronchial artery resistance by 40% and increased bronchial artery plasma 6-ketoprostaglandin F1α (194.7 ± 45.0 to 496.5 ± 101.3 pg/ml), the stable metabolite of prostacyclin, and prostaglandin (PG) F2α (28.1 ± 4.4 to 46.2 ± 9.7 pg/ml). There were no changes in PGD2, PGE2, thromboxane B2, adenosine, inosine, or hypoxanthine. Pretreatment with dipyridamole, an adenosine uptake inhibitor, did not affect bronchial artery nucleoside concentrations ( n = 7). Microsphere-induced vasodilation was not enhanced by dipyridamole ( n = 9) and was not inhibited by either the adenosine receptor antagonist xanthine amine congener ( n = 4) or the nitric oxide (NO) synthase inhibitor N G-monomethyl-l-arginine ( n = 8). These results do not support a role for either adenosine or NO and suggest that microspheres caused bronchial artery vasodilation through release of prostacylin and an unidentified vasodilator.
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Geffin, G. A., D. D. O'Keefe, A. G. Denenberg, and W. M. Daggett. "Microsphere reference flow samples during systemic flow adjustment." American Journal of Physiology-Heart and Circulatory Physiology 252, no. 4 (April 1, 1987): H851—H856. http://dx.doi.org/10.1152/ajpheart.1987.252.4.h851.

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Regional myocardial blood flow measurements in the right heart bypass preparation can be particularly valuable, since this preparation provides control of the main hemodynamic determinants of coronary blood flow. We examined the validity of aortic reference flow samples in relation to coronary samples during continuous systemic flow adjustment for aortic pressure control in six dogs on right heart bypass, anesthetized with chloralose and urethan. Microsphere concentrations were compared in paired reference flow samples drawn from the aortic arch and from a coronary artery for 119 left atrial microsphere injections. During left subclavian artery infusion and during femoral artery infusion at rates above 2,000 ml/min, there were high percentage errors in microsphere concentration between paired samples, consistent with aortic sample dilution by systemically infused blood. In 52 injections during withdrawal or femoral infusion below 2,000 ml/min, at cardiac outputs of 390-4,800 ml/min, the percentage error was 0.001 +/- 1.18% (SE); the absolute value of this error was below 20% in 96%, and below 10% in 77% of these injections. Linear regression related these coronary to aortic microsphere concentrations by the equation Y = 1.005X - 1.64, r = 0.997, Sy.x = 13.2 (5.9%). (Sy.x represents the standard deviation from regression.) These data indicate that valid aortic reference flow samples can be obtained within specific hemodynamic conditions during systemic flow adjustment in the right heart bypass preparation.
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Janssen, W. M., H. Beekhuis, R. de Bruin, P. E. de Jong, and D. de Zeeuw. "Noninvasive measurement of intrarenal blood flow distribution: kinetic model of renal 123I-hippuran handling." American Journal of Physiology-Renal Physiology 269, no. 4 (October 1, 1995): F571—F580. http://dx.doi.org/10.1152/ajprenal.1995.269.4.f571.

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A new technique for noninvasive measurement of intrarenal blood flow distribution over cortex and medulla is proposed. The technique involves analysis of 123I-labeled hippuran renography, according to a kinetic model that describes the flow of 123I-hippuran from the heart (input) through the renal cortex and medulla to the bladder (output). The method is validated and compared with the standard microsphere injection technique in anesthetized dogs. Changes in intrarenal blood flow distribution were induced by infusion of placebo (n = 6), angiotensin I (n = 5), or atrial natriuretic factor (n = 5). Baseline percentage medullary blood flow in the left kidney was 12 +/- 1% of total renal blood flow measured with microspheres and 15 +/- 1% with renography. During infusion of the placebo, medullary blood flow decreased slightly compared with baseline, as measured with both methods, by 2 +/- 6 (microspheres) and 1 +/- 8% (renography). Infusion of angiotensin I caused a marked fall in medullary blood flow by 42 +/- 11 (microspheres) and 57 +/- 8% (renography). In contrast, infusion of atrial natriuretic factor caused a small rise in medullary blood flow as measured with both methods (9 +/- 3 and 12 +/- 11%, respectively). The absolute and percent changes in medullary blood flow measured with renography correlated with those measured with microspheres (left kidney: r = 0.67, P = 0.005; r = 0.71, P = 0.003, respectively; right kidney: r = 0.62, P = 0.01; r = 0.68, P = 0.004, respectively). We conclude that the proposed kinetic model of renal 123I-hippuran handling can be used to measure changes in intrarenal blood flow distribution and, because of its noninvasive character, may be of use in clinical studies.
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Fischman, Alan J., Hongbing Hsu, Edward A. Carter, Yong M. Yu, Ronald G. Tompkins, J. Luis Guerrero, Vernon R. Young, and Nathaniel M. Alpert. "Regional measurement of canine skeletal muscle blood flow by positron emission tomography with H2 15O." Journal of Applied Physiology 92, no. 4 (April 1, 2002): 1709–16. http://dx.doi.org/10.1152/japplphysiol.00445.2001.

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Positron emission tomography (PET) with H2 15O was used as an in vivo, relatively noninvasive, quantitative method for measuring regional blood flow to hindlimb skeletal muscle of anesthetized dogs. A hydrooccluder positioned on the femoral artery was used to reduce flow, and high-flow states were produced by local infusion of adenosine. Three to four measurements were made in each animal. Approximately 40 mCi of H2 15O were injected intravenously, and serial images and arterial blood samples were acquired over 2.5 min. Data analysis was performed by fitting tissue and arterial blood time-activity curves to a modified, single-compartment Kety model. The model equation was also solved on a pixel-by-pixel basis to yield maps of regional skeletal muscle blood flow. After each PET determination, flow was measured with radioactive microspheres. Results of the PET measurements demonstrated that basal flow to hindlimb skeletal muscle was 3.83 ± 0.36 ml · min−1 · 100 g−1(mean ± SE). This value was in excellent agreement with the microsphere data, 3.73 ± 0.32 ml · min−1 · 100 g−1( P = 0.69, not significant). Adenosine infusion resulted in flows as high as 30 ml · min−1 · 100 g−1, and the PET and microsphere data were highly correlated over the entire range of flows ( r 2 = 0.98, P < 0.0001). We conclude that muscle blood flow can be accurately measured in vivo by PET with H2 15O and that this approach offers promise for application in human studies of muscle metabolism under varying pathophysiological states.
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Laptook, Abbot R., Janet Peterson, and A. Michael Porter. "Effects of Lactic Acid Infusions and pH on Cerebral Blood Flow and Metabolism." Journal of Cerebral Blood Flow & Metabolism 8, no. 2 (April 1988): 193–200. http://dx.doi.org/10.1038/jcbfm.1988.49.

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To determine the effects of lactic acidemia versus lactate on CBF, we infused lactic acid, either buffered with NaOH (L + NaOH) or with added NaCl (L + NaCl), to attain similar osmolalities in 18 piglets. CBF (microsphere technique), pH, blood gases, plasma osmolality, and cerebral arteriovenous differences of O2 content and lactic acid concentrations were measured prior to, at 30 min of a lactic acid infusion, and 15 and 90 min after completion of the infusion. Control arterial pH was comparable between groups (7.50 ± 0.02 vs. 7.49 ± 0.02, X̄ ± SE); during and following L + NaCl and L + NaOH, values were (p < 0.05) 7.09 ± 0.03, 7.35 ± 0.02, and 7.46 ± 0.02 vs. 7.58 ± 0.03,7.61 ± 0.01, and 7.57 ± 0.03, respectively. PaCO2 remained unchanged and osmolality rose by 15% in both groups during infusions and persisted throughout the study period. For L + NaCl piglets, CBF (ml/min · 100 g) rose from 136 ± 15 to 198 ±26 (p < 0.05) at 30 min of infusion and remained elevated at 201 ± 25 and 207 ± 28 at 15 and 90 min following the infusion, respectively. Similarly, for L + NaOH piglets, CBF rose from 130 ± 25 to 196 ±31 (p < 0.05) with the infusion and was 174 ± 17 and 166 ± 21 at 15 and 90 min afterward, respectively. Although lactic acid infusion increases CBF, the associated metabolic acidemia is not responsible for changes in CBF.
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Muhonen, Michael G., Scott C. Robertson, Jeffrey S. Gerdes, and Christopher M. Loftus. "Effects of serotonin on cerebral circulation after middle cerebral artery occlusion." Journal of Neurosurgery 87, no. 2 (August 1997): 301–6. http://dx.doi.org/10.3171/jns.1997.87.2.0301.

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✓ Serotonin (5-HT) produces constriction of peripheral collateral blood vessels. Using an animal model, the authors tested the hypothesis that 5-HT constricts collateral vessels in the cerebrum. A branch of the middle cerebral artery (MCA) was occluded proximally and cannulated distally in anesthetized dogs. Blood flow to the area at risk for infarction was detected by perfusing the cannulated MCA branch with microsphere-free blood during systemic injection of radioactive microspheres (shadow flow technique). Blood flow to collateral-dependent and normal cerebrum was measured during intravenous infusion of 5-HT (10 and 40 mg/kg/minute). Serotonin produced a dose-related reduction of blood flow to collateral-dependent cerebrum, increased collateral vessel resistance in large cerebral arteries and collateral vessels, and decreased cerebral artery perfusion pressure. In contrast, blood flow to normal cerebrum was not altered because a decrease in small vessel resistance effectively compensated for a decrease in MCA perfusion pressure. These findings indicate that 5-HT produces constriction of collateral vessels in the cerebrum. This response is clearly different from normal small cerebral vessels, which dilate during 5-HT infusion.
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Miura, T., S. Yoshida, O. Iimura, and J. M. Downey. "Dobutamine modifies myocardial infarct size through supply-demand balance." American Journal of Physiology-Heart and Circulatory Physiology 254, no. 5 (May 1, 1988): H855—H861. http://dx.doi.org/10.1152/ajpheart.1988.254.5.h855.

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We investigated dobutamine effect on infarct size during permanent coronary artery occlusion in dogs. The coronary artery of closed-chest dog was embolized by a 2.5-mm Teflon bead. Regional flow was measured 8 min after embolization with microspheres and, in drug-treated animals, again 20 min after starting dobutamine infusion (10 micrograms.kg-1.min-1 for 5 h immediately after the first microsphere measurement). The percent of the ischemic region progressing to infarct was determined 48 h later in each animal. Percent necrosis in the control group correlated closely with collateral flow to the epicardial one-third of the ischemic zone normalized against flow to the corresponding layer in the nonischemic zone. This flow should reflect an index of supply (collateral flow) and demand (flow to the nonischemic region determined by autoregulation). Percent necrosis in the drug-treated group did not correlate with normalized collateral flow measurement made before drug infusion, indicating that dobutamine had modified the course of infarction. Percent necrosis correlated well with normalized collateral flow measured during drug infusion, and that relationship was not different from that in the control group. Dobutamine increased infarct size over that expected from the predrug flow measurement in some dogs and reduced it in others. In all cases, however, the drug effect on infarct size was clearly reflected in normalized collateral flow measurement during drug infusion. Percent necrosis correlated with absolute collateral flow but less closely than with the normalized one.(ABSTRACT TRUNCATED AT 250 WORDS)
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Kuznetsova, Larisa V., Nicole Tomasek, Gisli H. Sigurdsson, Andrej Banic, Dominique Erni, and Anthony M. Wheatley. "Dissociation between volume blood flow and laser-Doppler signal from rat muscle during changes in vascular tone." American Journal of Physiology-Heart and Circulatory Physiology 274, no. 4 (April 1, 1998): H1248—H1254. http://dx.doi.org/10.1152/ajpheart.1998.274.4.h1248.

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Although the laser-Doppler flowmetry (LDF) signal from skeletal muscle has been shown to provide a good measure of blood flow under some conditions, its behavior during administration of vasoactive substances has never been addressed. The aims of this study were to compare 1) changes in LDF signal with those in total muscle blood flow measured with radioactive microspheres after ganglionic blockade (chlorisondamine) and during administration of angiotensin II (ANG II), phenylephrine (PE), and isoproterenol (Iso) and 2) changes in vascular resistance estimated by the two techniques. The LDF signal from the biceps femoris muscle was investigated in anesthetized male Wistar rats. Ganglionic blockade led to a significant ( P < 0.05) fall in mean arterial pressure (MAP) [medians (lower, upper quartiles): 78 (72, 83) vs. 127 (114, 138) mmHg under basal conditions], muscle blood flow (MBF, microsphere technique; 61%), and the LDF signal (29%). Muscle vascular resistance (MVR = MAP/MBF) was increased (64%, P < 0.05), but vascular resistance estimated as MAP/LDF signal (MVRLDF) was unchanged. During ANG II and PE infusions, MAP rose ( P< 0.05) to 178 (155, 194) and 127 (124, 142) mmHg, respectively; MBF did not change compared with the preinfusion (postganglionic blockade) level and remained significantly ( P< 0.05) lower than baseline, whereas the LDF signal increased up to a level not different from baseline. MVR rose and was significantly ( P < 0.05) higher than baseline, whereas MVRLDF did not differ significantly from baseline. During Iso infusion, MAP fell [58 (56, 60) vs. 94 (92, 102) mmHg, P < 0.05], the LDF signal was reduced (49%, P < 0.05) despite a large increase in MBF (139%, P < 0.05), and MVR fell (74%, P < 0.05), whereas MVRLDF did not change vs. preinfusion level. Our results suggest that 1) changes in the LDF signal from muscle may not correlate with changes in total muscle blood flow measured by the microsphere technique during infusion of vasoactive substances and 2) the use of LDF data for estimation of MVR during changes in vascular tone in rat skeletal muscle is probably not appropriate.
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Lertxundi, Unai, Jorge Aramburu, Julio Ortega, Macarena Rodríguez-Fraile, Bruno Sangro, José Ignacio Bilbao, and Raúl Antón. "CFD Simulations of Radioembolization: A Proof-of-Concept Study on the Impact of the Hepatic Artery Tree Truncation." Mathematics 9, no. 8 (April 12, 2021): 839. http://dx.doi.org/10.3390/math9080839.

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Radioembolization (RE) is a treatment for patients with liver cancer, one of the leading cause of cancer-related deaths worldwide. RE consists of the transcatheter intraarterial infusion of radioactive microspheres, which are injected at the hepatic artery level and are transported in the bloodstream, aiming to target tumors and spare healthy liver parenchyma. In paving the way towards a computer platform that allows for a treatment planning based on computational fluid dynamics (CFD) simulations, the current simulation (model preprocess, model solving, model postprocess) times (of the order of days) make the CFD-based assessment non-viable. One of the approaches to reduce the simulation time includes the reduction in size of the simulated truncated hepatic artery. In this study, we analyze for three patient-specific hepatic arteries the impact of reducing the geometry of the hepatic artery on the simulation time. Results show that geometries can be efficiently shortened without impacting greatly on the microsphere distribution.
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Dissertations / Theses on the topic "Microsphere infusion"

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Hu, Qiaohui. "Anatomy and physiology of bone perfusion in living and foss il birds as assessed by CT-scann ing, microsphere distribution, vascular contrast imaging and foramen measurement." Thesis, 2021. http://hdl.handle.net/2440/130171.

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Artery sizes are determined by local blood flow rates, which are driven by local oxygen demand. Arteries that pass through bone foramina, leave the foramina as size representatives of the arteries. Therefore, measuring these foramina sizes without any presence of soft tissue can be a way to estimate blood flow rates. This ‘foramen technique’ can be a useful tool to estimate blood flow rates in ancient animals such as dinosaurs. However, the absolute blood flow passing though foramina needs to be calibrated at this stage, as the size relationship between the foramen and occupying vessel is unclear, especially in foramina with more than one vessel. The major aim of this thesis is to evaluate the foramen-artery size relationship, especially the relationship between the femoral nutrient foramen and nutrient artery, to improve the method of femoral bone blood flow estimation for further foramen studies. Chickens are chosen as the experimental animals. Studying blood flow in birds gives us an opportunity to get insight into blood flow rates in dinosaur bones, as birds are living dinosaurs. The thesis chapters involve several methods to measure foramen sizes or estimate regional bone blood flow rates. Microphotography is chosen to be the most practical foramen measurement method compared to micro-CT and impression material approaches. Chicken femoral bone blood flow rates estimated from infusion of fluorescent microspheres and vascular contrast imaging give similar results. Foramen-artery size relationships are evaluated in chicken femur bones, revealing that the morphologies of femoral nutrient arteries and nutrient foramina can vary among femora. The ‘foramen technique’ is used to estimate femoral bone blood flow in fossil cursorial birds.
Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2020
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Book chapters on the topic "Microsphere infusion"

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Håkansson, Leif, Hans Starkhammar, Stefan Ekberg, Olallo Morales, Rune Sjödahl, and John Svedberg. "Degradable Starch Microspheres Infusion: Basic Considerations for Treatment of Hepatic Neoplasia." In Cancer Chemotherapy by Infusion, 588–99. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3193-0_43.

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Gyves, John W. "Selective Therapy of Hepatic Cancers Using Microspheres." In Clinical Applications of Continuous Infusion Chemotherapy and Concomitant Radiation Therapy, 67–69. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4613-2197-2_7.

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Parker, George, and William Regelson. "Biodegradable Starch Microspheres (Spherex), a Clinically Useful Medical Device for Combined Intra-Arterial Chemotherapeutic Treatment of Primary and Metastatic Cancers of the Liver: The Potential Clinical Value for Spherex in Regionalized Immunotherapy, Hyperthermia and Radiation Protection." In Clinical Applications of Continuous Infusion Chemotherapy and Concomitant Radiation Therapy, 51–66. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4613-2197-2_6.

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