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Biomedical subjects

Z Kan

Publications and source records attributed to Z Kan.

31 records · Page 2Linked to original sources
PubMed1994

Peribiliary plexa--important pathways for shunting of iodized oil and silicon rubber solution from the hepatic artery to the portal vein. An experimental study in rats.

OBJECTIVES: Iodized oil is commonly used in chemoembolization of hepatic tumors, and silicon rubber solution is used for casting studies of hepatic tumor vasculature. Understanding the distribution patterns of iodized oil and silicon rubber solution is of significance in the refinement of iodized oil techniques and proper interpretation of hepatic tumor vascular studies. In this study, the location for iodized oil and silicon rubber solution shunting from the hepatic artery to the portal vein was identified. METHODS: Iodized oil and silicone rubber solution were injected into the hepatic artery in rats. The porta hepatis and the liver periphery were examined using in vivo microscopy. RESULTS: Iodized oil and silicone rubber solution had identical distribution patterns in the hepatic circulation. Both were shunted in large quantities from the hepatic artery into the portal vein through the peribiliary plexa. Other potential shunting sites did not contribute to the shunting. CONCLUSIONS: Though of different chemical natures, iodized oil and silicon rubber solution share similar distribution patterns in the liver. Hepatic arterioportal shunting of these substances occurs via the peribiliary plexa.

Animals↗
PubMed1994

Role of Kupffer cells in iodized oil embolization.

RATIONALE AND OBJECTIVES: Iodized oil is a common oily embolic agent used in chemoembolization for treating hepatic tumors. However, how the iodized oil is cleared from the liver has been an unsettled and controversial issue. In this study, the authors attempt to clarify whether Kupffer cells are involved in the clearance of iodized oil and to evaluate the effect of hepatic arterial injection of iodized oil on the functional status of Kupffer cells. METHODS: Iodized oil was injected into the proper hepatic artery in 42 Fischer 344 rats. In vivo microscopy was performed immediately after and 1, 3, 7, 15, 30, and 60 days after injection. Electron microscopy was performed after in vivo microscopy. RESULTS: Kupffer cells actively captured and phagocytosed iodized oil droplets in the hepatic circulation. The number and functional status of Kupffer cells in the liver were significantly increased after the injection of the iodized oil and returned to normal when the liver was cleared of the oil. CONCLUSIONS: Kupffer cells play an important role in clearing iodized oil from the liver. Iodized oil activates the immune defense system in the liver, which may have a synergistic effect in tumor treatment.

Animals↗
PubMed1994

Preparation, characterization, and evaluation of ioxilan carbonate particles for computed tomography contrast enhancement of liver.

RATIONALE AND OBJECTIVES: To prepare and characterize a new particulate contrast medium, cyclic carbonate of ioxilan (IX-C) particles, as a macrophage imaging agent for computed tomography (CT) enhancement of the liver. METHODS: Cyclic carbonate of ioxilan was synthesized from ioxilan, a nonionic water-soluble contrast agent. The IX-C particles prepared by a solvent extraction-evaporation method were characterized by size distribution, degradability, suspension stability, and median lethal dose. Pharmacokinetics of IX-C particles and their effectiveness in enhancing liver attenuation and in detecting hepatic tumors were evaluated using normal and VX2-tumor-bearing rabbits. RESULTS: The IX-C particles were biodegradable, with ioxilan and carbon dioxide as the degradation products. The particles had an average size of 1 to 2 microns and were stable in saline suspension. The median lethal dose determined for IX-C particles was 2.6 and 3.1 g/kg body weight for female and male rabbits, respectively. A dose of 200 mg iodine/kg body weight caused an increase of 38 Hounsfield units in liver attenuation. In rabbit, hepatic clearance of the contrast medium occurred in 2 days. A tumor barely visible in precontrast scans could be detected after contrast injection. CONCLUSIONS: Development of particulate contrast medium from nonionic contrast agents represents a new approach. Ioxilan carbonate particles have suitable physicochemical properties that warrant further studies before clinical evaluation.

Animals↗
PubMed1993

Distribution and effect of iodized poppyseed oil in the liver after hepatic artery embolization: experimental study in several animal species.

To define the intrahepatic distribution of iodized poppyseed oil and its effect on the liver, hepatic artery embolization (HAE) was performed in five mice, 12 rats, four rabbits, and 21 pigs with the iodized oil alone or in combination with gelatin sponge powder (GSPow) in three rats or gelatin sponge particles (GSPs) in nine pigs. All mice, rats, and rabbits underwent radiography of the upper abdomen and in vivo microscopy of the hepatic periphery during and immediately after injection and 1, 4, and 24 hours later. All pigs underwent angiography before and after HAE as well as measurement of portal venous pressure before HAE and 15, 30, 45, and 60 minutes and 4 weeks after HAE. Follow-up radiographs were obtained in 18 pigs. HAE performed with the iodized oil only was well tolerated by the liver, even when high doses were used, likely because of continuous flushing of the sinusoids by high blood flow from peripheral arterioles. When HAE was performed with the iodized oil and GSPow, this blood flow ceased and necrosis developed. The degree of necrosis after HAE with the iodized oil in combination with GSPs was directly associated with the dose of iodized oil. HAE performed with GSPs only did not cause damage.

Animals↗
PubMed1993

In vivo microscopy of hepatic tumors in animal models: a dynamic investigation of blood supply to hepatic metastases.

The dynamics of blood circulation in three experimental animal models of hepatic metastasis were investigated with in vivo microscopy. It was demonstrated that the tumor vasculature communicated with the portal venules and hepatic sinusoids that surrounded the tumors. The hepatic artery was not seen to connect to the tumors directly. However, it was demonstrated that arterial blood entered tumors through the portal venules and that the hepatic arterial flow entered the tumor without resistance, while blood from the portal vein met great resistance at the tumor border, with only small amounts entering the tumor. Interruption of either the hepatic artery or the portal vein did not result in cessation of the blood circulation in hepatic tumors. A reciprocal relationship between the hepatic arterial and portal venous supplies to hepatic tumors was suggested, and it was hypothesized that arterioportal communications play an important role in the arterial and portal venous supply of blood to hepatic tumors. A comprehensive understanding of the blood supply of hepatic tumors is important for improving clinical treatment of hepatic tumors.

Adenocarcinoma↗
PubMed1992

Failure of cryopreserved homograft valved conduits in the pulmonary circulation.

BACKGROUND: This study evaluates our experience with the cryopreserved homograft valved conduit used for reconstruction of the pulmonary circulation in patients with congenital heart disease. METHODS AND RESULTS: Between July 1, 1985, and December 31, 1990, 219 patients had cryopreserved homograft extracardiac valved conduits placed in the pulmonary circuit. Average age at operation was 7.2 years. Of these, 132 patients had a pulmonary homograft, and 87 had an aortic homograft. Twenty-four patients (11%) died in hospital. Hospital survivors (n = 195) have been followed an average of 29.8 months (SD, +/- 18.4 months). Fourteen patients died during follow-up, almost all related to the complexity of their original cardiac malformation. Thirty-two patients (15%) have required reoperation for conduit-related problems. Actuarial freedom from conduit reoperation is 55 +/- 12% at 5 years. The most common indication for reoperation was calcific stenosis (n = 27). Other indications for reoperation were pseudoaneurysm (n = 2), conduit infection (n = 2), and pulmonary insufficiency (n = 1). Reoperation rate for patients with aortic homografts (16 of 87) compared with that for pulmonary homografts (16 of 132) was not significantly different by the actuarial method. CONCLUSIONS: Long-term function of cryopreserved homograft valved conduits in the pulmonary circulation is disappointing.

Actuarial Analysis↗
PubMed1991

Percutaneous gastrostomy. A clinical and experimental study.

Fluoroscopic percutaneous gastrostomy for the purpose of nutrition was performed in 28 patients with the aid of a specially designed gastrostomy set. No major complications were reported. Exchange to Foley catheter was performed after 7 days and could be used without complications for the patients' remaining life span. In order to evaluate the formation of a gastrocutaneous tract, an experimental study with the same instruments as in clinical practice was performed in 13 rabbits. Within one week a gastrocutaneous tract was formed, which was possible to dilate for insertion of a balloon catheter of larger size. The described procedure is a simple and time-saving method for a percutaneous gastrostomy in debilitated patients with dysphagia.

Aged↗
PubMed1989

[A case of hypertrophic obstructive cardiomyopathy with left atrial giant thrombus during anti-platelet therapy].

A case of a 77-year-old female with hypertrophic obstructive cardiomyopathy having the left atrial "giant" thrombus was reported; the diagnosis of the localization and size of the thrombus was made by employing echocardiography and contrast enhancement computed tomography as well. The clinical record indicated that the thrombus formation, which happened in the course of the antiplatelet therapy, was to be considered due to the complicated condition of the patient, i.e., the combination of atrial fibrillation, low cardiac output, enlargement of left atrium and left ventricular diastolic disfunction, which assumed to predispose the giant thrombus. Avoiding the surgical removal of the thrombus because of the poor conditions of the patient, urokinase treatment was attempted, but not successful, which might be derived from the nature of the thrombus already organized. In general, left atrial giant thrombus is very uncommon status; if any, it is occasionally complicated with mitral stenosis. The case reported deems to be very rare, enough worthy to be reported.

Aged↗
PubMed1988

Influence of 2-deoxy-D-glucose and arterial ischaemia on glucose oxidation and growth of liver cancer in the rat.

Malignant tissues are known to exhibit a high rate of glucose oxidation. It could therefore be hypothesized that reduction of glucose oxidation could be of benefit for the treatment of malignancies. We tested this approach, and by using [UL14C]glucose, we showed that glucose oxidation in a transplanted adenocarcinoma in the rat liver was 2.81 +/- 0.23 times as high as that of the surrounding liver tissue (P less than 0.01). In vivo treatment with intra-arterial 2-deoxy-D-glucose (2DG) infusion at 800 mg/kg via the gastroduodenal artery reduced the tumour/liver ratio of glucose oxidation to 1.88 +/- 0.12 (P less than 0.01). A similar inhibition of tumour glucose oxidation was obtained by 1 h of hepatic arterial ischaemia (P less than 0.05), or by ischaemia combined with 2DG infusion at 400 mg/kg (P less than 0.01). A 5-day course of intermittent hepatic dearterialization combined with continuous intra-arterial 2DG infusion at 400 mg/kg/day produced liver tumour growth retardation (P less than 0.01). We conclude that intermittent dearterialization reduces not only tumour growth but also the high tumour glucose oxidation. Dearterialization reduced glucose oxidation as much as 2DG did, which could be a mechanism behind reduced tumour growth.

Adenocarcinoma↗
PubMedDate not supplied

Sinusoidal embolization: impact of iodized oil on hepatic microcirculation.

PURPOSE: To determine the effects of iodized oil, which is used in chemoembolization of liver cancer, on hepatic microcirculation and to measure the time required for recovery of microcirculation. MATERIALS AND METHODS: Iodized oil was injected in 0.1-, 0.2-, and 0.4-mL/kg doses into the hepatic artery in three groups of rats (n = 63). In vivo microscopy was performed during and immediately after the procedure and on days 1, 3, 7, 15, 30, and 60. A control group of rats underwent identical microscopy procedures. RESULTS: Changes in microcirculation occurred after injections with iodized oil. Oil injected into the hepatic artery entered the portal vein and flowed into the sinusoids to create an incomplete sinusoidal embolization. Recovery of the sinusoidal circulation occurred 3, 7, and 30 days after injections of 0.1, 0.2, and 0.4 mL/kg of oil, respectively. CONCLUSIONS: The liver tolerated oil embolization well. Despite the changes in microcirculation and a nonlinear recovery time, the microcirculation completely recovered, even with a 0.4-mL/kg dose.

Animals↗
PubMedDate not supplied

Hepatic chemoembolization: clinical and experimental correlation.

Chemoembolization has become the preferred treatment for patients with inoperable, hypervascular hepatic malignancies in the Far East, but controversial elsewhere. In vivo microscopy in addition to other experimental procedures are used in this presentation to better understand the mechanisms involved in chemoembolization. In chemoembolization Lipiodol acts as a contrast material, a vehicle for chemotherapy and an embolic agent. Although not optimal, Lipiodol injected into the hepatic artery, traverses the peribiliary plexus to the portal veins resulting in a dual embolization. Chemoembolization creates ischemia, slows arterial flow and increases the contact time between the infusate and the neoplasms, increasing the tumor cell kill. However, the vascular occlusion also produces infarction and fibrosis compounding the already existing cirrhosis frequently associated with hepatocellular carcinoma. Lipiodol/ethanol (3:1) injected into the segmental or lobar hepatic artery supplying the neoplasm also gains access to the associated portal venous branches causing focal ablation. This preoperative approach is easier to perform than direct portal vein occlusion, with less parenchymal damage and comparable hypertrophy of the remnant liver frequently necessary for adequate hepatic function following resection. Polymer-drug conjugates, e.g. PG-TXL, have considerable potential for intra-arterial delivery especially with the dramatic increase in concentration of the drug in the tumor and its efficacy. Using in vivo microscopy especially with green fluorescent protein (GFP) gene as an efficient and non-toxic tumor cell marker, the events leading to hepatic metastases can be documented which will serve to better evaluate these varied techniques of chemoembolization.

Animals↗
PubMedDate not supplied

In vivo microscopy of the liver after injection of Lipiodol into the hepatic artery and portal vein in the rat.

The route, distribution and clearance of intraarterially administered Lipiodol in the liver has been the subject of much speculation. The hepatic microcirculation was therefore studied by in vivo microscopy after injection of Lipiodol into the hepatic artery and the portal vein in rats. After intraarterial injection, Lipiodol rapidly entered the portal branches through arterio-portal communications. Lipiodol also passed through the sinusoids from the portal into the hepatic veins and then into the systemic circulation. Sinusoidal congestion occurred when the oil droplets filled the liver microcirculation and resolved as the oil was cleared. It is of clinical significance to note the passage of the oil into the systemic circulation after arterial injection.

Animals↗