Role Of Reticuloendothelial System Research Articles

Fibronectin binds to amyloid P component. Localization of the binding site to the 31,000 dalton C-terminal domain

Fibronectin has been shown to play an important role in reticuloendothelial system functioning as well as in neutrophil and fibroblast migration to tissue injury sites. Fibronectin binds several macromolecules including components of the acute phase response. We have studied the interaction of fibronectin with the amyloid P component (AP). This glycoprotein, closely related to C-reactive protein, is deposited together with amyloid fibrils and is also a normal constituent of human tissues. AP-Sepharose affinity columns were used to determine the binding of fibronectin, its whole tryptic digest, and isolated fragments; fibronectin was retained by immobilized AP in a molar ratio fibronectin:AP of 1:5.8. In this paper we localized the binding site for AP in a tryptic 31 kDa fragment, near the C-terminal end of the fibronectin molecule. A shorter fragment of 22 kDa starting at position 82 of the 31 kDa domain and containing all the disulfide bridges present in the 31 kDa domain did not bind to AP; therefore the active site appears to be located within the 81 N-terminal residues of the 31 kDa fragment. To further support this conclusion, reduction and alkylation of either fibronectin or the 31 kDa fragment had no effect on their binding properties.

Bacterial clearance in the intact and regenerating liver

The Kupffer cells in the liver play an important role in reticuloendothelial system (RES) function by clearing particulate matter and bacteria from the blood stream. While hepatocyte regeneration and function have been extensively studied following partial hepatectomy, little information is available concerning RES function in the regenerating liver. This study investigates hepatic RES function by evaluating bacterial clearance (live E. coli) in the intact and regenerating liver. Thirty-four young male Sprague Dawley rats were studied. Twenty-two animals underwent a standard 70% partial hepatectomy using ligature technique and 12 had a sham operation. Both groups of rats received 10(9) organism of S35 labeled E coli, intravenously at 24 hours, 72 hours, 2 1/2 weeks, and 6 weeks postoperatively. Rats were killed 10 minutes following injection and liver, lung, spleen, and kidney harvested, fixed, and radioactivity was determined using a scintillation spectrometer interfaced with a micro-computer counting the S35 radiolabel. The total organ count of trapped bacteria in liver in partially hepatectomized rats was lower than intact controls at 24 hours (22.0% v 46.4%, P less than .01), but was similar at 72 hours, 2 1/2 weeks, and 6 weeks. Partial hepatectomy increased the amount of bacterial trapping in the lung at 24 hours (11.3% v 1.7%, P less than .01) and 72 hours (10.1% v 1.7%, P less than .05) and returned to normal at 2 1/2 weeks and 6 weeks. Splenic activity was increased following hepatectomy at 2 1/2 weeks. Renal clearance was increased at 72 hours and 2 1/2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma fibronectin in medical ICU patients.

Plasma fibronectin levels in 66 medical ICU (MICU) patients were measured daily. Mean values of initial levels were significantly higher in survivors (266 +/- 14 mg/L) than nonsurvivors (179 +/- 13 mg/L; p less than .0003). There was extensive overlap between survivors and nonsurvivors. The clinical categories of sepsis, disseminated intravascular coagulation (DIC), adult respiratory distress syndrome (ARDS), and hepatic failure with GI bleeding were associated with low fibronectin levels. Within all diagnostic categories the mean initial fibronectin level of the survivors was higher than that of nonsurvivors. This difference was significant only in the septic group (p less than .02). Patients with minimum fibronectin levels less than 195 mg/L had a 65% mortality rate; patients with minimum levels greater than or equal to 195 mg/L had a 17% mortality rate. Fibronectin, via its role in reticuloendothelial system (RES) function, may have a pathophysiologic role in a variety of medical illnesses.

Dose response curves for some immunosuppressive agents

Many immunosuppressive chemotherapeutic agents act largely through impairment of cell reproductive integrity. Using the Jerne's plaque assay, the inhibitory effect of nitrogen mustard, melphalan, 5-fluorouracil and 6-thioguanine on antibody formation was studied. It was observed that manipulation of the dose, frequency of administration and its timing in relation to immunization altered the magnitude of immunosuppression. In other experiments, the role of reticulo-endothelial system, thymic function and nutritional factors was found to be critical. For corresponding degrees of progressive immunosuppression, the dose of alkylating agents was increased in an arithmetic fashion and by log increments in the case of antimetabolites. There findings have relevance in formulating maximally effective therapeutic schedules with minimal toxicity.

Study on role of reticuloendothelial system in metabolic regulation.

This report deals with the relationship between liver L-Alanine: 2-oxoglutarate aminotransferaes ( EC 2. 6. 1. 2) activity and RES function. In fasted rats, decrease in .d4-3-ketost eroid hydrog en ase ( EC 1. 3. 1. 3 and 1. 3. 1. 4) and phagocy tic activity and increase in alanine aminot ransf eras e activity w er e noted. On the other hand, increas e in Ll4-3-ketos t eroid h ydrogenase and phagocytic activity and decrease in alanine aminotransferase activity were observed in RES stimulated ones. Possible mechanism for these changes in alanine aminotransferase activity was discussed in relation to the role of reti ­ culoendothelial system in steroid hormone metabolism.

155b Role of reticulo-endothelial system in the metabolism of some barbiturates

155b Role of reticulo-endothelial system in the metabolism of some barbiturates

Role of reticulo-endothelial system in blood clearance of cholesterol.

The clearance rate of colloidal carbon particles is only slightly impaired in rabbits rendered hypercholesteremic by overfeeding cholesterol. Rabbit serum cholesterol injected into rats is cleared by phagocytosis of the reticulo-endothelial cells whether the cholesterol is in the form of chylomicra (cloudy serum) or not (clear serum from fasting animals). The clearance of the foreign serum cholesterol from the blood follows an exponential function with respect to time as for many other colloids and the rate of clearance is inversely proportional to the quantity injected. Interference is observed between the clearance of cholesterol and other colloids when injected simultaneously. Pretreatment of rats with high doses of heparin increases substantially the speed of clearance of foreign serum cholesterol. The mechanism of the action of the R.E.S. in the metabolism of cholesterol is discussed.

Role of reticulo-endothelial system and disposition of dietary cholesterol in various mammalian species.

SummaryInterference with the reticuloendothelial system by injection of India Ink was found to interfere with the ability of the rat, rabbit and dog to clear their plasma after the ingestion of cholesterol dissolved in olive oil. This interference extended not only to cholesterol, but also to total lipid and chylomicra. These findings suggest that the reticuloendothelial system plays an essential role in the disposition of exogenously derived cholesterol. The possible mechanism involved is discussed.

Mechanism of Chemotherapeutic Action. II. Role of Reticuloendothelial System in Formation of a Parasitotropic Agent from Arsenicals.

Mechanism of Chemotherapeutic Action. II. Role of Reticuloendothelial System in Formation of a Parasitotropic Agent from Arsenicals.