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At least 19 recordsLinked to original sources
PubMed1994

Is it true that cardiac operations with cardiopulmonary bypass impair the reticuloendothelial system?

Reticuloendothelial system (RES) function after cardiac operations is a controversial issue. Sequential changes in plasma fibronectin levels and RES phagocytic function were studied after a cardiac operation and a lung operation (control). In the cardiac operation group, the plasma fibronectin level decreased until the third postoperative day and increased thereafter. Reticuloendothelial system phagocytic function remained unchanged on the third postoperative day and then it increased. However, in the control group it increased significantly after operation. In the past, investigators have demonstrated a decline in plasma fibronectin levels following cardiac operation and have assumed that RES function was impaired. However, this sequential study showed that phagocytic function was not impaired, but its enhanced phase was delayed. Moreover, our previous morphologic studies demonstrated that RES function was potentially activated after cardiopulmonary bypass. It appears that the delay of the enhanced phase is caused by the overloading of substances which must be processed by the RES during cardiopulmonary bypass. Thus, we conclude that cardiac operation produces hyperactive, yet oversaturated RES function. There is no impairment of RES function after cardiac operations.

Adult↗
PubMed1981

Interactions of liposomes with the reticuloendothelial system. Effects of reticuloendothelial blockade on the clearance of large unilamellar vesicles.

Large unilamellar liposomes (also called reversed phase vesicles or REVs) composed of DPPC and cholesterol are cleared from the circulation of the rat by a process which closely resembles the clearance of colloidal particles by the reticuloendothelial system. Thus, increasing the total amount of REVs administered by giving a loading dose of unlabelled REVs slows the clearance of a test dose of radioactively labelled REVs. This resembles the reticuloendothelial 'blockade' induced by large doses of colloids. Administration of other types of particles known to induce reticuloendothelial blockade, such as latex beads and xenogeneic red cells, also slows the clearance of radioactively labelled REVs. Administration of small unilamellar liposomes (SUVs) can also cause blockade of REV clearance, but the onset of blockade is delayed until a substantial fraction of the SUVs have been removed from the circulation. Blockade caused by the administration of large doses of REVs seems to result from a direct action on reticuloendothelial cells rather than from depletion of opsonic factors in the blood. Partial blockade of REV clearance produces a modest alteration of the tissue distribution of REVs, with enhanced uptake in the lungs. These results suggest that both REVs and SUVs are taken up by the reticuloendothelial system via a process which closely resembles the clearance of other types of colloids.

Animals↗
PubMed1993

Rates of systemic degradation and reticuloendothelial system (RES) uptake of thermosensitive liposome encapsulating cisplatin in rats.

The systemic degradation and reticuloendothelial system (RES) uptake of cisplatin (CDDP)-encapsulated thermosensitive liposomes composed of dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) (DPPC/DSPC = 9/1, 7/3, and 5/5, w/w) after intravenous administration to rats were examined by measuring the platinum (Pt) levels in the blood and RES (liver and spleen). The blood liposome level profile showed first-order rate elimination for each liposome administration. The elimination rate (Kel) was faster when the content of DSPC was lower (Kel: 1.3/hr for 9/1-liposomes, 0.7/hr for 7/3-liposomes, 0.5/hr for 5/5-liposomes). On the other hand, the RES liposome level profile showed distribution of liposomes followed by elimination therefrom. The RES level of the liposomes was lower when the content of DSPC was smaller (maximal level: 25% for 9/1-liposomes at 1 hr, 32% for 7/3-liposomes at 1 hr, 37% for 5/5-liposomes at 2 hr). The kinetic analysis demonstrated that the RES uptake rate (Kres) was almost the same among the liposomes (0.4/hr), while the systemic degradation rate (Kdeg; Kel-Kres) became larger as the content of DSPC decreased (0.9/hr for 9/1-liposomes, 0.3/hr for 7/3-liposomes, and 0.1/hr for 5/5-liposomes) and that the RES liposome distribution amount was dependent not only on the Kres but also on the Kdeg and the rate of RES liposome degradation. The Kdeg for each type of liposome corresponded with the systemic CDDP release rate.

Animals↗
PubMed1989

[Reliability of the lipid emulsion test for reticuloendothelial system].

The reticuloendothelial system is important as one of the self defense mechanisms. We performed two investigations to confirm the reliability of the lipid emulsion test for determining the reticuloendothelial system function. 1) The lipid emulsion serum clearance was contrasted with the counts of lipid emulsions phagocytosed by Kupffer cells in liver. 2) Lipid emulsion clearance was contrasted with the hepatic uptake rate of 99mTc-phytate. The result demonstrated a positive correlation among lipid emulsion clearance, the counts of lipid emulsions phagocytosed by Kupffer cells and the hepatic uptake rate of 99mTc-phytate. These results confirm that the lipid emulsion test is sufficient to reflect Reticuloendothelial system function.

Adult↗
PubMed1995

Rates of systemic degradation and reticuloendothelial system uptake of calcein in the dipalmitoylphosphatidylcholine liposomes with soybean-derived sterols in mice.

The systemic degradation and the reticuloendothelial system (RES) uptake of calcein entrapped in dipalmitoylphosphatidylcholine (DPPC) liposomes with soybean-derived sterols (SS) were examined after intravenous administration to mice by measuring the free and liposomal calcein levels in the blood. The results indicate that the rates of systemic degradation and the RES uptake of liposomes decrease with the addition of SS in DPPC liposomes since the SS has the ability to stabilize the liposomes. The rate of uptake by RES is larger than the rate of systemic degradation. The rate of leakage of calcein from liposomes by incubation in plasma in vitro is almost the same as that of systemic degradation in vivo.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1986

Cellular aging of the reticuloendothelial system.

The reticuloendothelial system (RES) consists of macrophages and other endocytic cells which contribute to natural resistance to disease agents. The RES has been implicated as being partly responsible for the observed age-related decrease in resistance to pathogenic microorganisms in man and experimental animals. It is largely unknown to what extent age-related deficiencies in specific functions of reticuloendothelial cells contribute to the decrease of RES functions. This study describes experiments focussed on Kupffer and endothelial cells of the liver which represent a major part of the RES and are primarily responsible for clearance of potentially harmful substances from the circulation. The age-related changes in the clearance of a RES test colloid (heat-aggregated colloidal albumin (CA)) and of E. coli endotoxin were investigated using female BN/BiRij rats of various age groups. With CA, studies were performed on the plasma clearance and on the endocytic capacity of whole liver and of Kupffer and endothelial cells in vivo, as well as on the kinetics of endocytosis by Kupffer cells in culture. The results showed that the plasma disappearance of endotoxin was significantly prolonged in rats of 24 and 36 months resulting in an increase in half-life of about 50% as compared to young rats. The plasma clearance of CA, the uptake by the liver and the endocytosis by endothelial cells were unchanged with age. In contrast, an age-related decrease in endocytic capacity was observed in Kupffer cells in vivo and in Kupffer cells which were isolated from rats of various ages and maintained in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗