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At least 181 records · Page 10Linked to original sources
PubMed1984

Tumoricidal response following perfusion over immobilized protein A: identification of immunoglobulin oligomers in serum after perfusion and their partial characterization.

Previously, we showed that perfusion of plasma from hosts bearing breast adenocarcinoma over immobilized staphylococcal protein A resulted in objective tumor regressions. In the present study, sera perfused in vitro over immobilized staphylococcal protein A were analyzed by physicochemical and immunochemical methods to characterize newly formed products. Sera from normal and breast adenocarcinoma-bearing dogs showed increased levels of C1q-binding IgG after perfusion over a strain of staphylococcus that is protein A rich (Cowan I), but not protein A deficient (Woods 46). C1q binding levels were also increased in normal and tumor-bearing canine or human sera which were perfused over purified protein A immobilized in collodion charcoal (PACC), and this increase was localized in sucrose density gradient fractions ranging from 7S to 19S. Polyacrylamide gel electrophoresis analysis of the high-molecular-weight fraction in postperfusion canine sera, isolated by G-200 fractionation and immunoaffinity chromatography, showed predominantly heavy and light immunoglobulin chains of canine IgG. Furthermore, protein A was released from PACC after perfusion with serum or solutions containing IgG or albumin from humans, dogs, and chickens. After serum perfusion over PACC, protein A was identified in the effluent by additional studies as follows: (a) polyacrylamide gel electrophoresis analysis showed that eluted 125I-protein A comigrated with the protein A marker; (b) postperfusion C1q-binding complexes, isolated by gel filtration under dissociating conditions and affinity chromatography on IgG-Sepharose showed a single precipitin band with normal human (protein A reactive) but not chicken (protein A unreactive) serum. Protein A released from PACC which appeared in postperfusion sera was associated with immunoglobulins in macromolecular complexes since (a) eluted 125I-protein A was largely (NH4)2SO4 and polyethylene glycol precipitable, whereas free protein A was not, and it sedimented in sucrose density gradient fractions distributed beyond the 7S marker, compared to free protein A which localized below 7S; (b) radiolabeled protein A eluting from PACC after serum perfusion showed 8-fold greater binding to C1q-coated tubes compared to free protein A; and (c) increased C1q-binding IgG in postperfusion sucrose density gradient fractions corresponded to the appearance of protein A in parallel gradient fractions.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed1993

[Effectiveness of continuous retrograde cerebral perfusion for surgical treatment of aneurysms of the aortic arch--comparison with antegrade cerebral perfusion].

Several methods have been used for an adjunct to perform operation of aortic arch aneurysms. However, their results were often not so reasonable. Recently retrograde cerebral perfusion was reported as a new adjunctive method. In our institute, for the past 6 and a half years from May 1985 to April 1992, 50 patients underwent reconstruction of the transverse aortic arch by using two methods of artificial cerebral perfusion. One method is continuous antegrade cerebral perfusion (ACP, for 32 patients), and the other is continuous retrograde cerebral perfusion (RCP, for 18 patients), each technique was combined with deep hypothermia (18-20 degrees C) and low flow perfusion (10-30 ml/kg/min) to lower half body performed from femoral artery. In our RCP circuit, an additional pump was used for cerebral perfusion to superior vena cava, but the circuit was much simpler than the circuit in ACP. We compared the two methods (ACP versus RCP) as regards to the following items and the results were showed in parentheses; hospital death (8/32, 25%: 2/18, 11%), respiratory complication (8.27, 30%: 3/18, 17%), neurological complication (7/29, 24%: 1/18, 5.5%), duration of extracorporeal circulation (306.8 +/- 74.5 min: 260.4 +/- 60.0 min), periods of pre-ECC in the operation (160.3 +/- 69.2 min: 117.7 +/- 35.3 min), duration of cerebral perfusion (113.6 +/- 45.4 min: 74.1 30.5 min) and amount of bleeding (3424 +/- 2881 ml: 1802 +/- 1291 ml). RCP has superior advantages in all of those in comparison with ACP. These results suggest that RCP is a useful adjunctive method for reconstruction of aortic arch with a low operative risk.

Adult↗
PubMed1996

Intermittent whole-body perfusion with "somatoplegia' versus blood perfusate to extend duration of circulatory arrest.

BACKGROUND: Continuous whole-body perfusion for > 3 hours with a cold asanguineous blood substitute, hypothermosol (HTS) solution, has been reported to preserve organ function. We used this solution in a survival animal model to evaluate its possible application in extending the safe duration of deep hypothermic circulatory arrest (DHCA). METHODS AND RESULTS: Fifteen piglets were placed on cardiopulmonary bypass (CPB), were cooled to a nasopharyngeal temperature of 15 degrees C, and underwent 100 minutes of DHCA. Control animals (group C, n = 5) had uninterrupted DHCA, group HTS animals were perfused with maintenance HTS for 5 minutes every 25 minutes during DHCA (n = 5), and group B animals were intermittently perfused as for group HTS with the blood in the bypass circuit (n = 5). Cerebral oxygenation was assessed with near-infrared spectroscopy throughout CPB and DHCA. Animals were allowed to recover after CPB and underwent daily neurobehavioral evaluation by the neurological deficit score (NDS: 0, normal; 500, brain death) and overall performance categories (OPC: 1, normal; 5, brain death). Blood samples were drawn on postoperative day (POD) 1 for selected biochemistry analysis. On POD 4, the brain of each animal was perfusion-fixed for histological evaluation, and a neurohistological score (NHS: 0, normal; 5+, necrosis) was assigned for the degree of neuronal injury. All animals except one from group HTS survived surgery. Mean perfusion pressures were significantly elevated in group B compared with group C and group HTS during the rewarming phase (P < .05). The HbO2 signal increased in all groups during the cooling phase of CPB and remained significantly above baseline only in group B during DHCA (P < .05). SGOT, LDH, ALP, and CPK levels on POD 1 were elevated above baseline in all groups. The increase in SGOT and ALP was significantly greater in group HTS than in the other groups (P < .02). The NDS was lower in group B on each postoperative evaluation, being significant relative to group C and group HTS on POD 1 (P < .05) and significantly lower than group C on POD 2 (P < .05). The OPC score was significantly lower in group B than in group C and group HTS on POD 2 (P < .05) and significantly lower than in group C on PODs 3 and 4 (P < .05). The NHS was lower in group B than in the other 2 groups, being significant relative to group C in the neocortex (P < .007). CONCLUSIONS: Intermittent whole-body asanguineous perfusion with hypothermosol solution does not extend cerebral protection in a porcine survivor model of DHCA. Neurobehavioral and histological outcomes are improved in animals receiving intermittent blood perfusion during prolonged DHCA.

Animals↗
PubMed1976

Studies of 5'-nucleotidase in the perfused rat heart. Including measurements of the enzyme in perfused skeletal muscle and liver.

Perfused rat hearts catalyze the hydrolysis of AMP added to the perfusion fluid at a rate of 35 mumol/g dry weight/min. The activity is specific for 5'-nucleoside monophosphates, little activity being observed with 2' and 3'-AMP. The enzyme exhibits Michaelis-Menten kinetics in situ and is inhibited competitively by adenosine-5'-alpha, beta-methylene diphosphonate (Ki = 13 muM). This, as well as the nucleotide specificity, confirms that the hydrolysis is catalyzed by 5'-nucleotidase. The maximum activity of 5'-nucleotidase in perfused hearts is equal to or greater than that found in heart homogenates; thus, all of the enzyme is accessible to AMP added externally. Hydrolysis of endogenous AMP was studied in the perfused heart. Under aerobic conditions hearts contain very low amounts of purine nucleosides, and little or no nucleoside is found in the effluent perfusate. Under anaerobic conditions hearts accumulate adenosine, inosine, and hypoxanthine and release all three substances into the perfusate. Hydrolysis of externally added AMP was also observed in perfused skeletal muscle and liver, at rates of 10 and 17 mumol/g dry weight/min, respectively.

Adenosine Monophosphate↗
PubMed1992

Prediction of reversible perfusion defects by quantitative analysis of post-exercise electrocardiogram-gated acquisition of technetium-99m 2-methoxyisobutylisonitrile myocardial perfusion scintigraphy.

The aim of this study was to assess the reliability of the quantitative analysis of regional wall thickening with electrocardiographic-gated technetium-99m 2-methoxyisobutylisonitrile (SESTAMIBI) in predicting the reversibility of stress-induced perfusion defects. The assumption was that a preserved resting wall thickening in a segment with stress-induced perfusion defect would predict normal resting perfusion. Twenty-five patients with suspected coronary artery disease underwent planar stress-rest SESTAMIBI scintigraphy. The wall thickening was quantitatively evaluated as percentage increase in counts from diastole to systole; a ratio defined as the wall thickening index (WTI) between patient and normal profile (mean - 2 SD) below 1 was considered abnormal. Improvement of the perfusion pattern at rest was observed in 76% (54/71) of segments with a stress-induced perfusion defect; 90% of these segments had a (WTI) greater than 0.8. Five segments (9%) showed fixed perfusion defects despite a WTI value greater than 0.8. In conclusion, quantitative analysis of regional wall thickening by electrocardiographic-gated SESTAMIBI identifies segments with reversible perfusion defects; this may overcome the need for studies at rest and may direct the detection of hypoperfused but viable myocardium.

Coronary Disease↗
PubMed2006

Decreased accuracy of pulse oximetry measurements during low perfusion caused by sepsis: Is the perfusion index of any value?

OBJECTIVE: To evaluate the effects of deteriorating perfusion caused by sepsis on the accuracy of pulse oximetry measurements using two more recently available techniques (Nellcor N-395 and Masimo Radical) and to evaluate the perfusion index as a marker of impaired peripheral perfusion to indicate that accuracy of pulse oximetry readings may be affected. DESIGN AND SETTING: Interventional cohort study in a university animal research facility. SUBJECTS: Thirty-seven adult anesthetized, ventilated rabbits. INTERVENTIONS: Pneumonia/sepsis was induced by tracheal instillation of Escherichia coli. MEASUREMENTS AND RESULTS: Oxygen saturation and perfusion index as a marker of peripheral perfusion were measured by pulse oximetry (SpO2) and recorded continuously for 8 h. Arterial oxygen saturation (SaO2) was measured every 30 min by CO oximetry, and bias (SpO2 - SaO2) was calculated at each time point for each device to assess time-dependent changes in bias. Bias increased significantly across time for both devices tested comparing the first with the second half of the experimental period. Bias measurements during the second half of the experimental time were beyond the +/-3% error limit in 21.4% of cases with Nellcor and in 22.6% with Masimo. A lower perfusion index was associated with increased bias, but sensitivity, specificity, and positive and negative predictive values of this marker for increased bias was very limited. CONCLUSIONS: We conclude that accuracy of pulse oximetry measurements was considerably affected with both devices with progressively deteriorating hemodynamics in this animal model of severe sepsis. Perfusion index as a marker for increased risk of bias was not a useful tool.

Animals↗
PubMed1990

Effect of plasma from essential hypertensives on vascular tone of aortic strips, isolated perfused mesentery and isolated perfused kidney.

Different vascular models of normotensive Wistar rats, including aortic strips, isolated perfused mesentery and isolated perfused kidney, were used to study hemodynamic effects of plasma fractions obtained by gel filtration from the blood of essential hypertensive and normotensive subjects. Plasma fractions from essential hypertensives studied had been shown to increase blood pressure after intravenous injection in rats. In the aortic strips, 50 microliters of a hypertensive fraction (HF) elicited a calcium-dependent contraction of 0.14 +/- 0.035 mN (n = 20, p less than 0.05), which was inhibited by nifedipine, whereas tension of the strips was not significantly changed by normotensive fractions (NF) (n = 17). In the isolated perfused mesentery preparation, no significant change of perfusion pressure by HF or NF could be demonstrated (n = 10). In the isolated perfused kidney, a transient increase of perfusion pressure was induced by HF (19.5 +/- 16.6 mm Hg, n = 40, P less than 0.001) but not by NF. This increase was abolished in calcium-free, 2 mmol/l EGTA containing perfusion medium. The response was diminished, but not abolished by nifedipine. These data demonstrate vasopressor properties of plasma from essential hypertensives, which might be the consequence of a circulating vasoconstrictor substance in the blood of essential hypertensives.

Adult↗
PubMed2005

From anatomic standardization analysis of perfusion SPECT data to perfusion pattern modeling: evidence of functional networks in healthy subjects and temporal lobe epilepsy patients.

RATIONALE AND OBJECTIVES: In the general context of perfusion pattern modeling from single-photon emission computed tomographic (SPECT) data, the purpose of this study is to characterize interindividual functional variability and functional connectivity between anatomic structures in a set of SPECT data acquired from a homogeneous population of subjects. MATERIALS AND METHODS: From volume of interest (VOI)-perfusion measurements performed on anatomically standardized SPECT data, we proposed to use correspondence analysis (CA) and hierarchical clustering (HC) to explore the structure of statistical dependencies among these measurements. The method was applied to study the perfusion pattern in two populations of subjects; namely, SPECT data from 27 healthy subjects and ictal SPECT data from 10 patients with mesio-temporal lobe epilepsy (MTLE). RESULTS: For healthy subjects, anatomic structures showing statistically dependent perfusion patterns were classified into four groups; namely, temporomesial structures, internal structures, posterior structures, and remaining cortex. For patients with MTLE, they were classified as temporomesial structures, surrounding temporal structures, internal structures, and remaining cortex. Anatomic structures of each group showed similar perfusion behavior so that they may be functionally connected and may belong to the same network. Our main result is that the temporal pole and lenticular nucleus seemed to be highly relevant to characterize ictal perfusion in patients with MTLE. This exploratory analysis suggests that a network involving temporal structures, lenticular nucleus, brainstem, and cerebellum seems to be involved during MTLE seizures. CONCLUSION: CA followed by HC is a promising approach to explore brain perfusion patterns from SPECT VOI measurements.

Adult↗
PubMed2005

Internal carotid blood flow and cerebral hemispheric perfusion in patients with subarachnoid haemorrhage: a study of the quantix/NDtrade mark system and CT perfusion technology.

OBJECTIVE: To assess whether carotid blood flow measurements predict abnormalities in cerebral hemispheric perfusion. DESIGN: The Quantix/NDTM system was used to measure carotid artery blood flow in nine patients with subarachnoid haemorrhage who underwent CT perfusion scanning. RESULTS: No significant correlation was found between internal carotid artery blood flow and ipsilateral cerebral hemispheric perfusion (013, p>0.05) but there was a statistically significant correlation between total internal carotid and global cerebral perfusion (0.63, p<0.05). CONCLUSIONS: This is the first report comparing the Quantix/NDTM system with CT perfusion. Our data do not show a statistically significant correlation between extracranial blood flow and cerebral hemispheric perfusion. This is in contrast to two previous studies where Quantix/NDTM measurements were compared with measurements of cerebral perfusion using the Xenon clearance technique.

Carotid Artery, Internal↗
PubMed1999

Transmyocardial laser revascularization with the Holmium:YAG laser does not improve myocardial perfusion in the acutely ischemic heart: an experimental study measuring myocardial perfusion by a thermal imaging camera.

BACKGROUND: Transmyocardial laser revascularization (TMLR) is a new surgical therapy for patients with end-stage coronary artery disease refractory to conventional therapy. TMLR should act by improvement of perfusion of the lasered myocardium. Blood should be delivered from the cavity of the heart to the surface of the myocardium. The aim of this study was to measure perfusion of normal, ischemic, and ischemic myocardium after TMLR. METHOD: We used a new method of perfusion measurement by an infrared thermal imaging system in an open-chested adult sheep model with temporary and permanent occlusion of the dominant diagonal branch. RESULTS: A significant fall from normal perfusion of the myocardium to reduced after inducing ischemia (p<0.01) and a significant rise again after reperfusion (p<0.001) could be shown. Perfusion measurements after TMLR did not significantly differ from perfusion measurements after inducing ischemia (p=0.2). CONCLUSION: In the presented sheep model, laser revascularization could not improve myocardial perfusion after acute ischemia as seen by the infrared thermal imaging system.

Aluminum↗
PubMedDate not supplied

Influence of calcium channel inhibitors on the myocardial uptake and retention of technetium 99m N-NOET, a new myocardial perfusion imaging agent: a study on isolated perfused rat hearts.

BACKGROUND: Technetium 99m N-NOET is a new myocardial perfusion imaging agent currently in phase III clinical trials in Europe. In vitro studies on newborn rat cardiomyocytes have shown that calcium inhibitors, such as verapamil or diltiazem, inhibit its cellular uptake by 40%. To determine whether such a specificity exists ex vivo, we studied the effect of verapamil, diltiazem, and nifedipine on the myocardial uptake and retention of Tc-99m N-NOET in isolated perfused rat hearts. METHODS AND RESULTS: After a 15-minute baseline period, rat hearts were perfused with 0.5 micromol/L verapamil (n = 6), 0.75 micromol/L diltiazem (n = 6), or 0.1 micromol/L nifedipine (n = 6) for 10 minutes before the injection of a bolus (40 microCi/250 microL) of the tracer. Control hearts were perfused with either 1.5 mmol/L calcium (same concentration as in the treated groups; n = 7) or 0.75 mmol/L calcium (same contractility as in the treated groups; n = 6). Myocardial activity of Tc-99m N-NOET was monitored for 30 minutes. The functional parameters of the hearts were recorded throughout the experiments. Calcium inhibitors induced a 40% to 55% decrease in maximal first derivative of left ventricular pressure (dP/dt) (0.0001<P< .001 versus control, calcium 1.5 mmol/L). After 30 minutes, tracer retention was 51.6%+/-6.1% injected dose (ID)/g and 54.2%+/-10.2% ID/g for control hearts perfused with 1.5 mmol/L and 0.75 mmol/L calcium, respectively (P = not significant). Myocardial activity of Tc-99m N-NOET was not modified in hearts perfused with verapamil (50.0%+/-4.1% ID/g), diltiazem (47.2%+/-8.7% ID/g), or nifedipine (51.7%+/-3.4% ID/g; P = not significant versus control hearts perfused with 1.5 mmol/L or 0.75 mmol/L calcium). CONCLUSIONS: Verapamil, diltiazem, and nifedipine were not responsible for any variations in Tc-99m N-NOET uptake and retention in the isolated rat-heart model. This might be explained by the binding of the tracer to endothelial cells, which do not present voltage-dependent calcium channels.

Animals↗
PubMedDate not supplied

Blood perfusion studies on basal cell carcinomas in conjunction with photodynamic therapy and cryotherapy employing laser-Doppler perfusion imaging.

Superficial blood perfusion was monitored using laser-Doppler perfusion imaging in connection with a phase III clinical trial comparing photodynamic therapy, utilizing topically applied delta-aminolevulinic acid, with cryotherapy of basal cell carcinomas. A total of 526 images were recorded before and immediately after the treatment and during the follow-up period. Before treatment, the lesions exhibited a blood perfusion 3+/-2 times that in normal tissue. Both treatment modalities induced an increased blood perfusion inside the lesions, which slowly approached normal values in conjunction with successful treatments. The blood perfusion in successfully treated lesions approached normal values 2 months after photodynamic therapy, and about 1 year after cryotherapy. The tissue perfusion in recurrent lesions did not decrease to normal values after the treatment, suggesting that the laser-Doppler perfusion imaging technique can be used to follow the healing process and discover possible persistent tumour growth.

Adult↗
PubMed1998

Changes of cerebral perfusion after osmotherapy in acute cerebral edema assessed with perfusion weighted MRI.

Perfusion is thought to be impaired in brain edema due to reduced perfusion pressure. Brain edema therapy is assumed to improve perfusion. We assessed regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and mean transit time of blood (MTT) using perfusion-weighted magnetic resonance imaging (MRI) in 15 patients showing acute local brain edema due to infarction or intracerebral hematoma. Patients were treated by intravenous infusion of 125 ml 40% sorbitol over 10 min. rCBF, rCBV and MTT in the edematous region were measured before and 30 min after treatment. Before treatment rCBF (46.5 +/- 12.1 vs. 42.9 +/- 10.5 ml 100 g-1 min-1), MTT (4.7 +/- 1.9 vs. 4.0 +/- 1.7 s) and rCBV (5.4 +/- 1.7 vs. 4.7 +/- 1.1 ml 100 g-1) were significantly (p < 0.05) increased in the edematous region compared to the contralateral side. After treatment no significant differences could be found. We interpret the elevation of MTT and rCBV in the edema as signs of an autoregulative compensation of an impaired perfusion. rCBF is even over-compensated. After brain edema therapy perfusion seems normalised. This new MRI method appears as useful for measuring therapeutic effects on cerebral perfusion.

Aged↗
PubMed1975

Glutamine production by the isolated perfused rat heart during ammonium chloride perfusion.

Myocardial levels of ammonia, glutamate, and glutamine and the release of glutamate and glutamine were studied in the isolated perfused rat heart during perfusion with ammonium chloride, epinephrine, and conditions of anoxia or ischaemia. Perfusion for 15 min with effective ammonium chloride concentrations of 0.53, 0.71, and 2.06 mmol/l resulted in glutamine production of 1.34, 0.95, and 4.41 mmol with 15 min-1/200 dry weight compatible with the presence of glutamine synthetase in rat myocardium. Myocardial ammonium content was unchanged by perfusion with 0.53 and 0.71 mmol/l ammonium chloride, but was increased by 1.36 mumol with 15 min-1/200 mg dry weight by perfusion with 2.06 mmol/l ammonium chloride. Increased myocardial contents of ammonia and glutamine were not accompanied by depression of left ventricular pressure. Perfusion with epinephrine (0.20 mug/ml) resulted in an increased myocardial content of glutamine. Anoxia or ischaemia resulted in no changes in ammonia content, and no changes in glutamine or glutamate production. The net release of glutamine into the perfusate was about 10 times the net release of glutamate.

Ammonia↗
PubMed1991

The isolated perfused human skin flap: design, perfusion technique, metabolism, and vascular reactivity.

The design, isolated perfusion technique, and reactivity of a novel human skin-flap model are described. A transverse paraumbilical skin flap based on perforator vessels from the deep epigastric system was designed utilizing the tissue usually discarded following abdominal dermolipectomy. Within 3 hours of devascularization, a gassed (95% O2, 5% CO2), 37 degrees C Krebs-Henseleit buffer containing albumin (65 gm/liter) was pumped into the cannulated arterial pedicle of the skin flap and subsequently collected from the venous pedicle. Vascular resistance was continuously monitored and remained stable throughout the 4-hour perfusion. Lactate release was maintained throughout perfusion and was markedly increased by addition of insulin to the perfusate. Addition of norepinephrine to the perfusate resulted in a significant (p less than 0.05) dose-response increase in vascular resistance, and acetylcholine significantly (p less than 0.05) attenuated resistance in flaps preconstricted with norepinephrine. The results of these studies indicate that the isolated perfused human skin flap remained metabolically active with functionally intact vascular endothelium and smooth muscle throughout the 4-hour perfusion. The availability of this technique will, for the first time, permit laboratory study of human skin-flap pathophysiology and pharmacology.

Animals↗
PubMed1996

The use of a novel monitoring apparatus and modified Belzer hydroxyethyl starch perfusate for analysis of glomerular filtration during hypothermic perfusion preservation.

The present study describes an experimental model for measurement of glomerular filtration during hypothermic perfusion preservation (HPP). To facilitate glomerular filtration during HPP, perfusate oncotic pressure was reduced by lowering the concentration of hydroxyethyl starch. Lewis rats underwent HPP at a mean perfusion pressure of 40-46 mmHg. An isograft model was used to demonstrate that retrieval and preparation for HPP did not impact adversely on renal function. Total cold ischemic time (CIT) consisted of the time from retrieval and preparation for perfusion (2 hr) added to the time of HPP. Tubular function studies demonstrated identical concentrations of Na+ and iohexol in ureteral effluent (UE) compared with circulating perfusate and, as such, established that UE flow represented a direct measure of glomerular filtration. Glomerular filtration rate (GFR) was then monitored during HPP by collecting UE in a beaker housed within a computerized Mettler balance system. GFR evolved in a characteristic, biphasic pattern during HPP, increasing from baseline values to reach a peak level at 4.8+/-0.3 hr of CIT and declining progressively thereafter. At 2.5 hr, time of peak values, 10 hr, 19.5 hr, and 24 hr of CIT, GFR values were 29+/-6 microl/min, 39+/-7 microl/min, 20+/-4 microl/min (n=15; P<0.01), 7+/-2 microl/min (n=14; P<0.001), and 14+/-6 microl/min (n=5), respectively. Intrarenal perfusate flows at the same time intervals were 4180+/-292 microl/min, 4083+/-290 microl/min, 3577+/-294 microl/min (P=NS), 1948+/-393 microl/min (P<0.001), and 2175+/-743 microl/min, respectively. Filtration fraction (FF) initially changed in parallel to glomerular filtration. Thereafter, FF either declined at a disproportionately slow rate compared with GFR (n=8) or increased rapidly (n=7). The data suggest that (1) primary change(s) in glomerular dynamics occur during HPP and (2) declining perfusate flow during the later stages of HPP reflects increasing renal vascular resistance localized at a postglomerular level. The data provide an experimental basis for investigating the clinical utility of monitoring glomerular filtration during HPP.

Animals↗
PubMed2005

Effect of inspiratory and expiratory breathhold on pulmonary perfusion: assessment by pulmonary perfusion magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The effect of breathholding on pulmonary perfusion remains largely unknown. The aim of this study was to assess the effect of inspiratory and expiratory breathhold on pulmonary perfusion using quantitative pulmonary perfusion magnetic resonance imaging (MRI). METHODS AND RESULTS: Nine healthy volunteers (median age, 28 years; range, 20-45 years) were examined with contrast-enhanced time-resolved 3-dimensional pulmonary perfusion MRI (FLASH 3D, TR/TE: 1.9/0.8 ms; flip angle: 40 degrees; GRAPPA) during end-inspiratory and expiratory breathholds. The perfusion parameters pulmonary blood flow (PBF), pulmonary blood volume (PBV), and mean transit time (MTT) were calculated using the indicator dilution theory. As a reference method, end-inspiratory and expiratory phase-contrast (PC) MRI of the pulmonary arterial blood flow (PABF) was performed. RESULTS: There was a statistically significant increase of the PBF (delta = 182 mL/100 mL/min), PBV (delta = 12 mL/100 mL), and PABF (delta = 0.5 L/min) between inspiratory and expiratory breathhold measurements (P < 0.0001). Also, the MTT was significantly shorter (delta = -0.5 sec) at expiratory breathhold (P = 0.03). Inspiratory PBF and PBV showed a moderate correlation (r = 0.72 and 0.61, P < or = 0.008) with inspiratory PABF. CONCLUSION: Pulmonary perfusion during breathhold depends on the inspiratory level. Higher perfusion is observed at expiratory breathhold.

Adult↗
PubMed1984

Myocardial perfusion with rubidium-82: III. Theory relating severity of coronary stenosis to perfusion deficit.

The relation between the quantitative perfusion deficit, as measured by emission computerized tomography, and the severity of coronary artery stenosis is important for the noninvasive clinical evaluation of coronary artery disease in man. Positron emission tomography allows direct noninvasive measurement of myocardial perfusion and quantification of the size of the perfusion defect. Given this important information, a mathematical model has been derived to gauge the severity of a coronary stenosis from quantitative perfusion measurements in the normal and poststenotic regions of the heart. The theoretical basis is presented for relating regional myocardial perfusion and regional perfusion resistance to total coronary blood flow and resistance at normal resting flow and during maximal coronary vasodilation. The concept of perfusion reserve is presented as a clinical measure of the severity of a stenosis.

Coronary Circulation↗