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PubMed1976

Radiocirculographic study of the effect of ethyl apovincaminate on the cerebral circulation.

The effect of ethyl apovincaminate (RGH-4405, Cavinton) on cerebral circulation has been studied with radiocirculography (rc) in 12 healthy individuals and 17 patients suffering from cerebrovascular diseases. It was shown that acute Cavinton effect produced prolongation of circulation time both in healthy individuals and in more than half of our patients. Shortening of circulation time was observed in one case. On long-term Cavinton treatment circulation time was prolonged in 7 cases, not changed in 7, while in 3 cases it was shortened. The circulation times measured by rc did not reflect changes in the clinical picture.

Adult↗
PubMedDate not supplied

A new analysis method for disposition kinetics of enterohepatic circulation of diclofenac in rats.

The pharmacokinetics of diclofenac, which is definitely subject to enterohepatic circulation in rats, was evaluated. The pharmacokinetic model for enterohepatic circulation was constructed in the Laplace-transformed domain by means of the transfer function method of the signal flow. The transformed equations were simultaneously fitted to the time courses of plasma concentration averaged over two groups of rats [i.e. one with an intact enterohepatic circulation and the other without an enterohepatic circulation by means of the bile duct cannula (double-lines fitting)]. The transformed equations were also fitted to each plasma time course in the individual rat (single-line fitting). It was demonstrated that the estimated pharmacokinetic parameters by the single-line fitting almost coincided with those by the double-lines fitting. The local moments for a single pass through enterohepatic circulation were also calculated from the time courses of both the plasma concentration and the amount excreted into the bile. In the nonanesthetized group, the recirculation ratio (Fc) and the mean recirculation time (tc) of diclofenac were estimated to be 21.1% and 4.5 hr, respectively. The absorption ratio (Fa) and the mean absorption time (ta) from the intestinal tract were 52.2% and 4.29 hr, respectively. The experiments using bile duct cannulation revealed that the total amounts excreted into the bile were 14.4% in the anesthetized group and 40.4% in the nonanesthetized group of rats, and that diclofenac was excreted 95% as the glucuronide form and 5% as the intact form in both groups.

Animals↗
PubMedDate not supplied

The afferent circulation of the liver in patients with primary hepatocellular carcinoma.

BACKGROUND/AIMS: The data on the afferent circulation of the liver, in patients with primary hepatocellular carcinoma, are controversial or non-existent. MATERIALS AND METHODS: The authors measured hepatic arterial and portal venous flow intra-operatively by transit time ultrasonic volume flowmetry. RESULTS: In patients with primary hepatocellular carcinoma, the hepatic artery flow increased to 0.55 +/- 0.21 l, as compared with the control value of 0.37 +/- 102 l/min (p < 0.01). The portal venous flow decreased from 0.61 +/- 0.212 l/min to 0.47 +/- 0.203 l/min p < 0.01). Owing to the opposite changes in the afferent circulation, the total hepatic blood flow did not change significantly. The ratio of hepatic arterial flow to portal vein flow increased to 1.239 +/- 0.246 in patients with hepatocellular carcinoma, which is twice the basic control value (0.66 +/- 0.259 l/min). After resection, this ratio showed virtually no change. The surgical intervention, that is resection of the liver, did not significantly alter hepatic artery and portal venous flow, although total hepatic blood flow decreased significantly (p < 0.01). The pronounced increase in the ratio of hepatic arterial flow may be attributed to the decrease in portal venous flow caused by the primary hepatocellular carcinoma. The decrease in venous flow can most probably be explained by compression and infiltration of the intrahepatic branches of the portal vein. As we pointed out, the decrease in portal venous circulation leads to an increase in hepatic arterial flow. CONCLUSIONS: On the basis of our initial results, it seems probable that the ratio of the two circulations represents a diagnostic tool for the altered circulation in patients with hepatocellular carcinoma. The significance of this phenomena is not yet quite clear, but a review of the literature shows that similar observations have not been reported. In practical terms this phenomenon may be useful from the point of view of US and Doppler US diagnosis, e.g. in the case of a hypo-echoic or hyperechoir, mass in the liver, increased blood flow in the hepatic, artery, and decreased portal venous flow, a malignant liver tumor is virtually certain. The authors hypothesise that any pathology in the liver may lead to a primary decrease in PVF and a subsequent increase in HAF.

Adult↗
PubMed1977

Specific removal of antibody by extracorporeal circulation over antigen immobilized in collodion-charcoal.

Studies were undertaken to determine whether BSA immobilized in collodion membranes adherent to activated charcoal particles, would be capable of specifically removing circulating BSA antibody in vitro and in vivo in an extracorporeal system in dogs. Up to 59-8 mg of BSA were retained in collodion membranes adherent to small particles. In vitro studies demonstrated that immobilized BSA could specifically reduce BSA binding activity from circulating antisera. For in vivo studies, an extracorporeal circulation system was established and arterial blood was circualted through a continuous flow celltrifuge in which plasma was separated from formed elements of the blood. Only plasma was circulated over the BSA collodion-charcoal immunoadsorbent. Anti-BSA and anti-HSA atibodies were passively infused into dogs and, after an equlibration period of 12 or 15 min, plasma was passed over the BSA collodion-charcoal immunoadsorben. Plasma exhibited a sharp reduction in BSA binding over the next 30-60 min with only slight reduction in anti-HSA binding the same period. Dogs, actively immunized to BSA and HSA, were also treated by extracorporeal plasma perfusion over BSA collodion-charcoal. A specific decline in BSA binding of sera, was again observed with minimal changes in HSA binding. A post-perfusion rebound of BSA binding was observed which reached pre-perfusion levels after 6-8 days. A second treatment during the rebound period also resulted in a specific decline in BSA binding with a similar pattern of antibody rebound. There were no significant changes in I-labelled BSA recorded on the charcoal before and after in vivo procedures and no signifcant alterations in haematocrit, serum sodium, potassium, calcium, magnesium or creatinine levels before and after the procedures. These data suggests that antigen-coated charcoal may specifically withdraw circulating antibodies in vivo with minimal release of the entrapped antigen and little alteration in the host's haematological and biochemical status.

Animals↗
PubMedDate not supplied

Collateral circulation in occlusion of lower limbs arteries: an anatomical study and statistical research in 35 old subjects.

The collateral circles formed following lower limbs arterial occlusion and their hemodynamic function have been described; 35 subjects (23 men and 12 women; age range 65 to 80), with symptomatic lower limbs obstructive arteriopathy (Fontaine's stage II) following occlusion of vessels downstream the subrenal aorta have been studied by means of Contrast Angiography and Color Doppler Echography of the vascular district including the terminal aorta and the lower limbs arteries. The hemodynamic significance of the collateral circles was assessed by calculating the Windsor index. In this population, the collateral circles for each level of obstruction were explored. Occlusion of the terminal abdominal aorta: the collateral circle was mainly established through the inferior mesenteric and ischiatic arteries and through the lumbar, ilio-lumbar and gluteal arteries; occlusion of the iliac tract: the collateral circulation was established through the spermatic or ovaric artery and through the funicular, external pudendal and middle sacral arteries; occlusion of the ilio-femoral tract: the collateral circulation was formed by the internal and external pudendal arteries and by the ilio-lumbar, obturating, gluteal and circumflex iliac arteries; occlusion of first tract of the superficial femoral artery: collateral circulation was established through the deep femoral artery and through the perforating arteries; occlusion of the terminal tract of the superficial femoral artery: collateral circulation was formed by the articular branches of the same artery originating proximal to the occlusion and through branches of the deep femoral artery; occlusion of the superficial and deep femoral arteries at their origin: collateral circulation was established through the ischiatic artery (directly and, indirectly, through the perforating arteries), and through the tegumental arteries. The hemodynamic significance, as measured by Windsor index was higher the more proximal was the occlusion, in accord with the lower caliber and/or number of vessels involved in the collateral circles.

Aged↗
PubMed1997

Ongoing prothrombotic state in the portal circulation of cirrhotic patients.

Portal thrombosis may complicate the clinical course of cirrhosis, but the pathophysiologic mechanism is unclear. Aim of the study was to evaluate the behavior of clotting system and endotoxemia in portal vein and in peripheral circulation of 11 cirrhotic patients undergoing transjugular port-systemic shunt (TIPS). Portal blood showed higher values of F1 + 2 [Median (range): 2.5 (1.1-5.3) vs. 1.1 (0.6-2.1) nM, p < 0.01], D-dimer [765 (184-1713) vs. 192 (64-813) ng/ml, p < 0.01] and endotoxemia [31 (16-47.2) vs. 13.7 (7.5-23.5) pg/ml, p < 0.01] than peripheral circulation. In the portal vein, all but one sample had F1 + 2 > 1.2 nM (upper limit of control values), all but one had D-dimer > 216 mg/dl (mean + 2 SD of controls) and 100% had values of endotoxemia > 9.6 pg/ml (upper limit of control values). Fibrinogen was lower in the portal circulation compared to peripheral circulation but the difference was not significant [85 (58-195) vs. 134 (75-244) mg/dl, p > 0.05]. Endotoxemia was directly correlated with F1 + 2 (Rho = 0.92 p < 0.006) and D-dimer (Rho = 0.93, p < 0.005). This study shows that an ongoing prothrombotic state is present in the portal circulation of cirrhotic patients and may play a pivotal role in the thrombotic episodes occurring in this clinical setting.

Adult↗
PubMedDate not supplied

Effect of collateral circulation on healing of small intestinal anastomosis in rabbits.

BACKGROUND/AIMS: In patients who have acute superior mesenteric artery occlusion and clearly gangrenous intestines, resection and anastomosis have been advised as the only surgical procedure. Distal and proximal bowel segments adjacent to this necrotic part have collateral blood supply although they have normal macroscopic appearance. After resection of necrotic segment, there will be a low flow at the anastomosis due to collateral circulation and the healing may therefore be impaired. METHODOLOGY: This situation was investigated in rabbits creating unilateral collateral circulation at the small bowel anastomosis. Bursting pressure, tissue hydroxyproline concentration and bursting sites were determined on days 4, 8, and 12. Findings were compared with the those of normal anastomosis. RESULTS: There was significantly decreased mean bursting pressure(106 +/- 40.3 mmHg) in unilateral collateral circulation group as compared with the that of control group (158 +/- 26.6 mmHg) on day 8 (p < 0.05). On the same day mean hydroxyproline concentration of this group was also lower(7.06 +/- 0.5 mg/g tissue) than the value of control group(7.69 +/- 0.4 mg/g tissue), with the statistical significance on the border line(p = 0.05). The low values of these two parameters reached normal levels on day 12. Bursting sites were mostly on the anastomotic line in unilateral collateral circulation group, while they were mostly on the bowel wall in the control group on day 8. CONCLUSION: These findings suggest an insufficient healing process in the bowel anastomosis with unilateral collateral circulation on day 8 in rabbits.

Anastomosis, Surgical↗
PubMed1989

[The effects of administration of haptoglobin for hemolysis by extracorporeal circulation].

It is well known that hemolysis by extracorporeal circulation is major cause of renal failure after open heart surgery. The purpose of this study is to investigate the effects of administration of haptoglobin (Hp) during extracorporeal circulation. The patients were divided into two groups: Group I 10 patients underwent open heart surgery for extracorporeal circulation; Group II 10 patients underwent open heart surgery for extracorporeal circulation with the administration of 4,000 IU of Hp. The serum level of total Hp was elevated in group II during bypass, and reduced at 1st day in both groups more than pre-operative level. The serum level of total Hb was elevated in both groups during bypass, and reduced at 1st day within normal limits. Free serum Hb was found in group I at 30 min after start bypass and increased during bypass and urinary Hb was also found. However, in group II free Hb was not found during and after bypass. Urinary NAG and alpha 1 Mg levels of group I were significantly higher than those of group II. The administration of Hp during extracorporeal circulation prevents the increment of serum free Hb and is effective for protection of renal function.

Acute Kidney Injury↗
PubMed1998

Effects of topical nipradilol, a beta-blocking agent with alpha-blocking and nitroglycerin-like activities, on aqueous humor dynamics and fundus circulation.

PURPOSE: To study the effects of nipradilol, a nonselective beta-blocker with alpha 1-blocking activity and nitroglycerin-like activity, on aqueous humor dynamics and optic nerve head (ONH) circulation in albino rabbits. METHODS: Experiments were carried out during the dark phase, in conscious rabbits conditioned to a schedule of alternating 12-hour periods of light and dark. The blood-aqueous barrier permeability and the aqueous flow rate were determined fluorophotometrically. The effect on outflow to general blood circulation and uveoscleral outflow were determined by using the fluorophotometric Diamox technique, and the effect on the uveoscleral outflow was further assessed by using the anterior chamber perfusion method. The ONH circulation was estimated by using the laser speckle method. RESULTS: Unilateral topical administration of 0.25% nipradilol solution lowered intraocular pressure (IOP) with relatively weak contralateral effects in a dose-dependent manner with a maximum reduction of 6 mm Hg and an effect duration of 6 hours. Twice-daily instillation for 14 days showed no attenuation of the effects. Single instillation of 0.25% nipradilol showed no significant effect on blood-aqueous barrier permeability and decreased aqueous flow rate in the treated eye (17%; P < 0.01) and in the contralateral eye (9%, P < 0.05). Nipradilol produced no significant effect on outflow facility to general blood circulation, whereas it substantially increased uveoscleral outflow. Twice-daily 0.25% nipradilol instillation increased ONH tissue blood velocity by 13% (P < 0.01), which was probably attributable to locally penetrating drug. CONCLUSIONS: Because of its ability to lower IOP and to increase uveoscleral outflow and optic nerve head circulation in rabbits, further studies are warranted to determine whether nipradilol has potential as an antiglaucoma agent in humans.

Administration, Topical↗
PubMed1976

Evaluation in dogs of cross-circulation in the treatment of acute hepatic necrosis induced by yellow phosphorus.

The efficacy of cross-circulation in the treatment of acute liver failure has been evaluated in dogs. Four of 5 dogs administered a dose of yellow phosphorus that is lethal 90% of the time survived after treatment by cross-circulation of whole blood for between 1 and 8 hr with a normal dog. In 2 normal unmatched dogs plasma cross-circulations were performed over a period of 31 days without any clinical or laboratory manifestation of hypersensitivity except for lymphocytotoxic antibody titer rise. The results suggest that whole blood cross-circulation is effective and imply that a single donor could be utilized for prolonged periods of plasma cross-circulation with avoidance of immunological consequences of whole blood exchange.

Acute Disease↗
PubMed1998

Cholesterol homeostasis in human brain: turnover of 24S-hydroxycholesterol and evidence for a cerebral origin of most of this oxysterol in the circulation.

We have previously demonstrated that the brain contains about 80% of the 24S-hydroxycholesterol in the human body and that there is a net flux of this steroid from the brain into the circulation (Lütjohann, D. et al. 1996. Proc. Natl. Acad. Sci. USA. 93: 9799-9804). Combining previous data with new data on 12 healthy volunteers, the arteriovenous difference between levels of this oxysterol in the internal jugular vein and in a peripheral artery was found to be -10.2 +/- 2.8 ng/ml (mean +/- SEM) corresponding to a net flux of 24S-hydroxycholesterol from the brain of about 6.4 mg/24 h. The arteriovenous difference between levels of 24S-hydroxycholesterol in the hepatic vein and a peripheral artery of 12 other volunteers was found to be 7.4 +/- 2.2 ng/ml, corresponding to a hepatic uptake of about 7.6 mg/24 h. The concentrations of 24S-hydroxycholesterol in the renal vein were about the same as those in a peripheral artery, indicating that a renal elimination is not of importance. Intravenously injected deuterium-labeled racemic 24-hydroxycholesterol was eliminated from the circulation of two human volunteers with half-lives of 10 h and 14 h, respectively. A positive correlation was found between the levels of circulating cholesterol and 24S-hydroxycholesterol. The results are consistent with a cerebral origin of most of the circulating 24S-hydroxycholesterol and suggest that the liver is the major eliminating organ. It is concluded that conversion into 24S-hydroxycholesterol is a quantitatively important mechanism for elimination of cholesterol from human brain. The possibility is discussed that circulating levels of 24S-hydroxycholesterol can be used as a marker for pathological and/or developmental changes in the brain.

Adult↗
PubMedDate not supplied

[Relation between mitral orifice surface area and extent of hemodynamic disorder of the pulmonary circulation in patients with mitral stenosis].

UNLABELLED: Mitral annulus and valves form the mitral orifice area with the size between 4.0-6.0 cm2. Every area which is smaller than this, represents mitral stenosis. As a consequence of mitral stenosis hemodynamic gradients occur over the mitral orifice with circulation disturbances below and above the stenotic mitral valve. The size of transmitral gradient is important in the evaluation of functional or/and structural changes in the blood vessels of pulmonary circulation. This investigation included 40 patients with mitral stenosis (or accompanying minimal mitral regurgitation). All patients underwent echocardiographic examination: area of the mitral orifice was determined and hemodynamic procedure with the left and right heart catheterization was performed. The following hemodynamic parameters were measured: mean capillary wedge pressure, left ventricular filling pressure, left ventricular mean diastolic pressure, mean pulmonary artery pressure. According to these parameters resistance in the pulmonary circulation was measured. The size of the mitral orifice was determined according to oximetry blood analyses and hemodynamic parameters. All patients were divided into 4 groups: minimal (2.5-4.0 cm2), mild (1.5-2.5 cm2), moderate (1.0-1.5 cm2) and severe mitral stenosis (1.0 cm2). The comparison of echocardiographic and hemodynamic parameters revealed a high and positive correlation between the area of mitral orifice. There was also a negative and moderate correlation between the values of stenotic mitral orifice area and total pulmonary resistance, i.e. in all patients with severe mitral stenosis there was an increased pulmonary arteriolar resistance. CONCLUSION: Noninvasive echocardiographic method is valid in the evaluation of stenotic mitral valve area. In the evaluation of hemodynamic parameters in the pulmonary circulation the index of arteriolar pulmonary systemic vascular resistance is very important. In all patients with the area of stenotic mitral orifice 1.0 cm2, there are functional or pathomorphologic changes in the pulmonary circulation of the blood vessel wall.

Echocardiography↗
PubMed1998

Effects of L-arginine on the systemic, mesenteric, and hepatic circulation in patients with cirrhosis.

Nitric oxide (NO) is known to play an important role in modulating both the hepatic and mesenteric circulation under physiological and pathological conditions. We investigated how L-arginine, a precursor of NO, modifies the hepatic and mesenteric circulation in patients with cirrhosis. The study design was a single-blind controlled study. We measured the systemic and portal hemodynamics before and following intravenous L-arginine and saline infusion using pulsed Doppler ultrasonography in 20 patients with cirrhosis, and then the effects were compared with those found in 20 healthy subjects. In these patients, the effects of L-arginine on hepatic circulation were investigated using hepatic catheterization. L-Arginine infusion induced systemic vasodilation in both the healthy controls and the cirrhotic patients in a similar hemodynamic manner. In these patients, the L-arginine-induced increase in the portal flow was significantly higher than that of cardiac output (CO); however, the relation was the inverse in healthy subjects. Moreover, the L-arginine-induced increase in the portal flow was greater in the cirrhotic patients than that seen in healthy subjects. As a result, L-arginine infusion was thus found to selectively augment the hepatopetal portal blood flow in the cirrhotic liver. In patients, L-arginine infusion induced marked hepatic vasodilation as demonstrated by the reduced hepatic sinusoidal resistance (HSR) and increased estimated hepatic blood flow (EHBF) associated with the ameliorated intrinsic clearance of indocyanine green. Despite the fall in HSR, the hepatic venous pressure gradient (HVPG) increased following L-arginine infusion. The mesenteric and hepatic vascular areas of cirrhosis exhibited an increased susceptibility to the dilator action of L-arginine. These findings suggest that the enhanced NO production in the splanchnic vascular area has an important role in the hepatic circulation in patients with cirrhosis.

Aged↗
PubMed1990

Computer simulation of the mechanically-assisted failing canine circulation.

A model of the cardiovascular system is presented. The model includes representations of the left and right ventricles, a nonlinear multielement model of the aorta and its main branches, and lumped models of the systemic veins and the pulmonary circulation. A simulation of the intra-aortic balloon pump and representations of physiological compensatory mechanisms are also incorporated in the model. Parameters of the left ventricular model were set to simulate either the normal or failing canine circulation. Pressure and flow waveforms throughout the circulation as well as ventricular pressure and volume were calculated for the normal, failing, and assisted failing circulation. Cardiac oxygen supply and consumption were calculated from the model. They were used as direct indices of cardiac energy supply and utilization to assess the effects of cardiac assistance.

Animals↗
PubMed1984

Cardiac, thoracic, and abdominal pump mechanisms in cardiopulmonary resuscitation: studies in an electrical model of the circulation.

To investigate alternative mechanisms generating artificial circulation during cardiopulmonary resuscitation (CPR), an electrical model of the circulation was developed. Heart and blood vessels were modeled as resistive-capacitive networks; pressures in the chest, abdomen, and vascular compartments as voltages; blood flow as electric current; blood inertia as inductance; and the cardiac and venous valves as diodes. External pressurization of thoracic and abdominal vessels, as would occur in CPR, was simulated by application of half-sinusoidal voltage pulses. Three modes of creating artificial circulation were studied: cardiac pump (CP), in which the atria and ventricles of the model were pressurized simultaneously; thoracic pump (TP), in which all intrathoracic elements of the model were pressurized simultaneously; and abdominal pump (AP), in which the abdominal aorta and inferior vena cava of the model were pressurized simultaneously. Flow was greatest with the CP, less with the TP, and least with the AP mechanism. However, the AP could be practically combined with either the CP or TP by interposition of abdominal compressions between chest compressions (IAC-CPR). Our model predicts that this combined method can substantially improve artificial circulation, especially when cardiac compression does not occur and chest compression invokes only the thoracic pump mechanism.

Abdomen↗
PubMed1986

Effects of ACE-inhibition on regional circulation in congestive heart failure.

During development of heart failure there are marked changes in the peripheral circulation. The renal and splanchnic circulations are reduced early. The cerebral circulation is maintained by autoregulation. Skeletal muscle blood flow is reduced in relation to the decrease of cardiac output. There are also important metabolic changes in these muscles with reduced mechanical efficiency. Treatment with arterial vasodilators increase cardiac output. However, most of this increase is usually shunted, probably in the splanchnic circulation. If any, only small increases in muscle blood flow have been reported. ACE-inhibition has been shown to have beneficial acute effects on the renal, cerebral and skeletal muscle blood flow with improved flow in these areas. This treatment seems to be the most beneficial vasodilatory alternative available so far.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2005

Initial Glasgow Coma Scale score predicts outcome following thrombolysis for posterior circulation stroke.

BACKGROUND: Randomized trials of thrombolytic stroke treatment have either excluded patients with posterior circulation ischemia or used inclusion criteria making enrollment of these patients less likely. Consequently, there is less published information on thrombolytic therapy for posterior circulation stroke. OBJECTIVE: To determine effective thrombolytic treatment times for posterior circulation stroke and factors that might help predict clinical outcome. DESIGN: We describe our experience treating 21 consecutive patients with either intravenous or intra-arterial thrombolytic therapy for posterior circulation ischemic stroke between October 9, 1993, and February 19, 2001. MAIN OUTCOME MEASURES: National Institutes of Health Stroke Scale, Glasgow Coma Scale, and modified Rankin Scale scores were evaluated at baseline, and the modified Rankin Scale was measured 3 months after stroke, with a good outcome being a modified Rankin Scale score of 2 or less. RESULTS: Nine patients received intravenous therapy; 12 patients received intra-arterial therapy. The median National Institutes of Health Stroke Scale score at onset was 20 (range, 2-39), and the median Glasgow Coma Scale score was 9 (range, 3-15). Twelve patients were treated within 8 hours of symptom onset (range, 1 1/2 hours to 16 days). Nine patients (43%) had a modified Rankin Scale score of 2 or less at 3 months. The initial Glasgow Coma Scale score and treatment within 8 hours of symptom onset were each associated with good outcome, but the initial National Institutes of Health Stroke Scale score was not predictive. CONCLUSIONS: Thrombolytic therapy for posterior circulation stroke may be beneficial even when initiated 8 hours after symptom onset. Level of consciousness, as measured by Glasgow Coma Scale score, seems to be a more important predictor of outcome than the initial National Institutes of Health Stroke Scale score.

Adult↗
PubMed1996

In vivo trafficking of long-circulating liposomes in tumour-bearing mice determined by positron emission tomography.

Various kinds of long-circulating liposome, such as ganglioside GM1-, polyethyleneglycol- (PEG-), and glucuronide-modified liposomes, have been developed for passive targeting of liposomal drugs to tumours. To evaluate the in vivo behaviour of such long-circulating liposomes, we investigated the liposomal trafficking, especially early trafficking just after injection of liposomes, by a non-invasive method using positron emission tomography (PET). Liposomes composed of dipalmitoylphosphatidylcholine, cholesterol, and modifier, namely, GM1, distearoylphosphatidylethanolamine (DSPE)-PEG or palmityl-D-glucuronide (PGlcUA), were labelled with [2-18F]-2-fluoro-2-deoxy-D-glucose ([2-18F]FDG), and administered to mice bearing Meth A sarcoma after having been sized to 100 nm. A PET scan was started immediately after injection of liposomes and continued for 120 min. PET images and time-activity curves indicated that PEG liposomes and PGlcUA liposomes were efficiently accumulated in tumour tissues time dependently from immediately after injection. In contrast, GM1 liposomes accumulated less in the tumour as was also the case for control liposomes that contained dipalmitoylphosphatidylglycerol (DPPG) instead of a modifier. Long-circulating liposomes including GM1 liposomes, however, remained in the blood circulation and avoided liver trapping compared with control DPPG liposomes. These data suggest that PGlcUA and PEG liposomes start to accumulate in the tumour just after injection, whereas GM1 liposomes may accumulate in the tumour after a longer period of circulation.

1,2-Dipalmitoylphosphatidylcholine↗