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PubMedDate not supplied

Effects of chemically defined structured lipid emulsions on reticuloendothelial system function and morphology of liver and lung in a continuous low-dose endotoxin rat model.

BACKGROUND: This study was undertaken to determine the effect of chemically defined structured lipids on nonspecific host defense and on histologic patterns of liver and lungs compared with a physical mixture of long-chain triglycerides and medium-chain triglycerides in a continuous low-dose endotoxin rat model. METHODS: Forty male Sprague-Dawley rats, divided into four feeding groups (structured lipids, structured lipids+endotoxin, physical mixture, physical mixture+endotoxin), received total parenteral nutrition for 48 hours. During the first part of the study, 24 animals were given an injection of live Escherichia coli labeled with radioactive iron (59Fe) to investigate the function of the reticuloendothelial system. During the second part of the study, the liver and lungs of 16 animals were histologically examined using light and electron microscopy. RESULTS: Despite the similar values in the control groups, the animals receiving structured lipids+endotoxin sequestered a significantly greater percentage of bacteria in the liver and spleen (p < or = .01) and a significantly lesser percentage in the lung (p < or = .05) compared with the animals given physical mixture+endotoxin as part of their diet. Moreover, rats in the physical mixture+endotoxin group showed a microscopically evaluated higher fatty infiltration in the liver than did the structured lipids+endotoxin group. CONCLUSIONS: The results of this study indicate that chemically defined structured lipids reduce fatty infiltration of the liver compared with a physical mixture of the same compounds in an animal model of metabolic stress. They were accompanied by a better function of the reticuloendothelial system and a lesser bacterial sequestration in the lungs.

Animals↗
PubMed1988

The three different phases of reticuloendothelial system phagocytic function in rats with liver injury.

In the present study, reticuloendothelial system (RES) phagocytic function of rats with partial hepatectomy or experimentally induced liver cirrhosis was investigated by determining the phagocytic index, the opsonic index, and uptake rate in liver, spleen, and lung of a 51Cr-labeled endotoxin-injected rat. In both the partially hepatectomized and the cirrhotic rats, all three indicators varied markedly according to the elapsed period since liver injury. The changes in RES phagocytic function were classified into three different phases: compromised, compensatory, and enhanced. The compromised phase, consisting of a decrease in the phagocytic index, was observed during the first 24 hr after 67% hepatectomy and in advanced liver cirrhosis. This represented the failure of RES phagocytic function. The compensatory phase, in which the phagocytic index was maintained at nearly normal levels mainly by a compensatory enhancement in the opsonic index, was seen during the first to second postoperative day and in moderate liver cirrhosis. The enhanced phase, with a high phagocytic index, was observed from Day 4 to approximately Day 14 after surgery, and in the cases of mild liver damage. In the compromised and compensatory phases, the liver uptake rate was significantly decreased compared with the control. However, the uptake in the spleen and lung were markedly increased. In conclusion, the phagocytic function of the RES was significantly affected to a degree which changed with the extent of liver damage.

Animals↗
PubMed1984

Effects of methylprednisolone on the Fc-receptor function of human reticuloendothelial system in vivo.

To determine whether the Fc-receptor function of reticuloendothelial system (RES) is modified by corticosteroid administration, we studied the spleen to liver uptake ratios of autologous, 99Tc-labelled heat-damaged or IgG-coated erythrocytes, injected intravenously into 10 normal volunteers, 4 h after receiving a single dose of 32 mg of methylprednisolone by mouth. In standard conditions, quantitative scans indicated that the spleen to liver uptake ratios, calculated per unit area 40 min after the injection of labelled erythrocytes, were 13.4 +/- 0.6 and 31.2 +/- 1.5 (mean values +/- -SEM), for the heat-damaged (n = 7) and IgG-coated red cells (n = 5) respectively. Four hours after corticosteroid administration, the spleen to liver uptake ratios were significantly reduced in five of ten volunteers. Abnormal ratios correlated with the Fc-receptor function of monocytes measured in vitro using IgG-coated erythrocytes. Indeed, 2-6 h after methylprednisolone was given, the Fc-receptor binding activity of monocytes isolated from the same five subjects was reduced by at least 50%, spontaneously returning to a rather normal value 4-6 h later. The C3-receptor binding activity of these monocytes remained normal, after otherwise identical experimental conditions. These results show a transient, specific impairment of the Fc-receptor function of RES after methylprednisolone administration, and may therefore explain, in part, the infectious complications occurring in some patients treated by corticosteroids.

Adult↗
PubMed1995

Dynamic liver scintigraphy: a new way of measuring the function of the reticuloendothelial system of the liver.

The phagocytic function and biokinetics of the hepatic reticuloendothelial system (RES) were evaluated using a 25-nm diameter colloid (Nanocoll) and a scintillation camera technique in opossums with obstruction of the pancreatic duct (group I) and additional obstruction of the common bile duct (group II). The liver net uptake curve was analysed using natural log regression. The regression curves proved to fit very well (r > 0.93) and a parameter R was calculated to describe the curves. In group I there was a slight but significant decrease in the RES function and no morphological change in the pancreas. In group II, RES function was significantly more suppressed than in group I. The opossums developed severe haemorrhagic pancreatitis. The results show that the regression parameter R is well suited to described liver RES function, and suggest that a suppressed liver RES after biliary obstruction could be an important factor in the pathogenesis of biliary pancreatitis.

Animals↗
PubMed1980

Resistance to experimental peritonitis induced by local nonspecific stimulation of the reticuloendothelial system.

Zymosan, a yeast cell wall preparation from Saccharomyces cerevisiae, stimulates the reticuloendothelial system (RES) in animals. Pretreatment with zymosan induces resistance to several types of shock. We have shown evidence that zymosan given intraperitoneally (IP) induces greater protection than intravenous (IV) zymosan against E coli peritonitis in the rat. Moreover, IP zymosan has few systemic RES effects, which are commonly associated with IV zymosan. IV and IP zymosan stimulation were compared for effectiveness against experimental fibrinopurulent peritonitis in dogs (a peritonitis model quite similar to clinical peritonitis). Ten dogs received zymosan IV (10 mg/kg), ten dogs received zymosan IP (10 mg/kg), and eight dogs received an equal volume of saline IP on three consecutive days. On day 4, a 7.5 cm length of terminal ileum was isolated and its blood supply ligated to create an infarcted, blind loop of bowel. This loop was left in the peritoneal cavity for five days. Five-day survival was 80% (8/10) for the zymosan IP (P less than 0.05), 60% (6/10) for the zymosan IV and 12.5% (1/8) for the saline controls. All survivors were sacrificed at five days and found to have an intact enteric anastomosis with varying degrees of walled-off abscess at the site of the necrotic loop. Histologic evaluation of intraabdominal organs, peritoneum, and abscess wall was carried out. The IP zymosan had no significant systemic RES effects, whereas the IV zymosan produced a marked increase in liver and spleen weights. These findings reinforce the hypothesis that local nonspecific RES stimulation could have a major role in the preparation of certain high-risk patients for abdominal surgery where the chance of peritoneal soilage is high.

Animals↗
PubMed1994

[The reticuloendothelial system. An overview of function, pathology and recent methods of measurement].

The Reticuloendothelial System (RES) consists of cells descending from the monocytes which are able to perform phagocytosis of foreign materials and particles. 90% of the RES are located in the liver. The most important function of the RES ist phagocytosis, but it also takes part in cytotoxicity against tumor cells and has a function in the regulation of the immune system. The importance of the RES is obvious in diseases of the bile ducts. An obstruction can lead to a decrease in the function of the RES. Beside a mathematical model there are also a few experimental methods to measure the phagocytic capacity and thus the efficiency of the RES. They are based on a clearance study of the amount of particles absorbed by the RES. This study can e.g. be done with Nanocoll which has been marked with 99mTc. But instead of the bloody clearance, a scintigraphic study using a gamma camera can be performed. With that, the increase time, the liver extraction fraction and the steepness of increase can be determined. Such a test could be of clinical relevance as a parameter for the prognosis of patients with trauma, sepsis or shock. The function of the RES in the pathogenesis of the biliary pancreatitis could also be examined closer with the help of such a test. The requirements a test of the RES should meet are reproducibility, repeatability and practicability.

Animals↗
PubMed1996

Augmentation of endotoxin-induced pulmonary responses by mononuclear cell phagocytosis in the reticuloendothelial system.

OBJECTIVE: To test the hypothesis that the effects of intravenous injection of latex particles would demonstrate the contribution of phagocytosis by mononuclear phagocytes to the development of Escherichia coli-induced acute lung injury in neutropenic guinea pigs. DESIGN: Prospective, controlled, experimental study. Intravenously injected the latex particles into 41 guinea pigs to investigate the contribution of the phagocytosis in acute lung injury. SUBJECTS: Forty-one guinea pigs. INTERVENTIONS: Forty-one guinea pigs were divided into five experimental groups: a saline group (n=9); an endotoxin group (n=10) receiving 2 mg/kg of intravenous E. coli endotoxin; a latex group (n=7) receiving 2 x 10(9)/kg of intravenous polystyrene latex (mean diameter 3.19 micrometers); an endotoxin + latex group (n=8); and an E. coli group (n=7) receiving 2 x 10(9) live E. coli/kg. MEASUREMENTS AND MAIN RESULTS: The lung wet/dry ratio was increased in the live E. coli-treated guinea pigs (6.71 +/- 0.16 [SEM], p < .01) as compared with the saline control (5.40 +/- 0.16, whereas the ratio was not increased in the endotoxin (5.52 +/- 0.14) or latex (5.58 +/- 0.20) groups. However, the lung wet/dry ratio was greater in the endotoxin + latex group (6.11 +/- 0.16, p < .05) than in the saline control. The 125I albumin lung tissue/plasma ratio was greater in the E. coli (2.00 +/- 0.29, p < .01) and endotoxin + latex (0.84 +/- 0.12, p < .05) groups than in the saline group (0.18 +/- 0.07), whereas no increases were observed in the endotoxin group (0.22 +/- 0.10) and the latex (0.34 +/- 0.13) group. More than 40% of the injected radiolabeled latex was observed to have accumulated in the reticuloendothelial system (liver and spleen), in both the saline control (40.1 +/- 2.3%, n=4) and endotoxin (57.3 +/- 6.8%, n=5) groups, with 2.6 +/- 1.5% and 3.1 +/- 1.7% in the lungs for the saline control and the endotoxin groups, respectively. The percent deposition of radiolabeled latex in the liver was greater in the endotoxin group (51.7 +/- 3.8%, p < .05) than in the saline group (37.6 +/- 5.9%). CONCLUSIONS: These findings suggest that, in neutropenic guinea pigs: a) the combination of endotoxin and latex particles induces acute lung injury; and b) the phagocytic properties of mononuclear phagocytes in the reticuloendothelial system augment endotoxin-induced pulmonary responses and may play a role in the development of live E. coli-induced acute lung injury.

Animals↗