Lars Berghem

Adsorption behavior of fibronectin on well-characterized silica surfaces

The adsorption behavior of human plasma fibronectin at physiological pH and ionic strength was investigated by in situ ellipsometry on silica substrates of two different surface energies. The silica substrate was characterized by ellipsometry, galvanic potential, and critical surface tension measurements. Adsorption isotherms in the low concentration range for fibronectin were compared with human fibrinogen and found to be qualitatively similar with increased amounts of protein adsorbed at the plateau on a hydrophobic surface as compared to a hydrophilic one. Reversibility for fibronectin upon dilution was found to be small on a hydrophobic surface while a partial desorption was found on a hydrophilic one. Interaction of antibodies with preadsorbed fibronectin suggests that fibronectin adsorbs in different conformations and/or arrangements on the two types of surfaces. The lectin Concanavalin A and its interaction with preadsorbed fibronectin was also investigated.

Human Granulocyte and Reticuloendothelial System Function During Intra lipid Infusion

In six patients, the phagocytic and catabolic functions of the RES (reticuloendothelial system), as measured by using 125I-microaggregated human serum albumin as a test substance, were not affected by Intralipid infusion. The nitroblue tetrazolium (NBT) reduction of granulocytes, the NBT reduction and the bacplasma, was significantly lower in eight patients during Intralipid infusion than before this treatment. When heat-killed E. coli were added for phagocytic stimulation in vitro, the same result was obtained only in the absence of plasma. The bactericidal capacity of granulocytes was significantly decreased in six patients during Intralipid infusion. When Intralipid was added in vitro to granulocytes, the NBT reduction, and the bactericidal capacity of these cells were decreased and the effect was mainly dose-dependent. Electron micrographs show that granulocytes phagocytize Intralipid. The loading of granulocytes with lipid particles may block the engulfment of bacteria and may be a reason for the decreased bactericidal capacity of these cells. An influence exerted by the lipid on the cell membrane is the most conceivable reason for the decreased NBT reduction.

Exogenous Hyaluronic Acid (Healon®) Accelerates the Healing of Experimental Myringotomies

Topical application of hyaluronic acid (Healon) onto the borders of rat tympanic membrane perforations accelerated the rate of wound healing. The closure time was roughly 60% of that of the untreated perforations. Epithelial cells fused with opposing cells slightly in advance of supporting connective tissue and thus bridged the remaining gap. It seems as if hyaluronic acid, topically applied, can serve as a supporting and orienting matrix for the proliferating squamous epithelium.

Influence of Cardiopulmonary Bypass on Some Host Defence Functions in Man

Four different functions of the immune defence were studied in six men undergoing open-heart surgery with cardiopulmonary bypass (CPB). Pre-operatively, a few hours after and three days after surgery the following tests were performed: (I) in vivo phagocytic and metabolic functions of the reticuloendothelial system (RES), (II) haemolytic activity of blood monocytes, (III) nitroblue tetrazolium (NBT) reduction by granulocytes, and (IV) bactericidal capacity of granulocytes. Compared to the pre-operative values, the RES functions were unchanged postoperatively, whereas there was a significant increase in the haemolytic activity of monocytes and in the NBT reduction of granulocytes. The capacity of the granulocytes to kill bacteria was normal a few hours after surgery, but significantly increased on day 3. No infectious complications occurred and all patients recovered uneventfully. These results suggest that, at the present time, open-heart surgery under CPB is accompanied by an increased activity of granulocytes and monocytes in the early postoperative period.

Reticuloendothelial function in human renal allograft recipients.

The phagocytic and metabolic functions of the reticuloendothelial system (RES) were determined, by measuring the plasma clearance rate of 125I-labelled microaggregated human serum albumin and the increase in plasma metabolites of this test substance, in patients with chronic renal failure and in renal transplant recipients at different times after transplantation. All transplant recipients received triple immunosuppressive therapy consisting of azathioprine, corticosteroids, and antilymphocyte globulin. The intravascular clearance of microaggregated albumin was significantly depressed in patients when tested at 1 to 12 days (P < 0.001), 1 to 4 months (P < 0.02), and 6 to 9 months (P < 0.001) after transplantation compared to pretransplantation. The 1− to 3-year transplant survivors had a normal RES phagocytosis. Furthermore, the metabolic RES function in all groups of transplant recipients except the group of patients tested at 1 to 4 months after transplantation was significantly impaired compared to pretransplantation. Administration of antilymphocyte globulin and extremely high daily doses of steroids were probably responsible for the significant depression in the RES functions recorded immediately post-transplantation. The further development of the phagocytic ability of the RES was shown to be correlated to the cumulative dose of steroids given over the last 12 months. The azathioprine regime seemed to have no influence on the RES functions. The RES is a major host defence mechanism against bacterial and viral infections (1–4) and tumour growth (5–7). Macrophage phagocytosis and metabolism are also important in the induction of an immune response to foreign antigens (8–10) and in the rejection of allografts (11, 12). Depression of the RES function induced by various agents (methyl palmitate, trypan blue, silica, carrageenan, or antimacrophage serum) was shown to prolong the survival of organ as well as tumour grafts (13–17). On the other hand, glucan-induced stimulation of the RES was associated with enhanced rejection of both tumour and bone marrow transplants (14, 17). Immunosuppressive agents such as azathioprine, corticosteroids, and antilymphocyte serum, used in transplantation surgery to suppress the immune response, have been reported to impair RES phagocytosis (18–21). Several investigations have been made in animals and some in man on the capacity of the RES to clear various colloids and lipid emulsions from the circulation (22–25). In recent years, moreover, methods have been developed for the determination of not only the phagocytic but also the metabolic function of the RES (26–28). Those used most frequently utilize a rapidly metabolizable RES test substance of microaggregated human serum albumin labelled with radioactive iodine, a substance which can safely be used in man (26, 28). The purpose of the present study was to determine both the phagocytic and the metabolic functions of the RES in patients undergoing renal transplantation during immunosuppressive therapy. As RES test substance, microaggregated human serum albumin labelled with 125I was used.

Fibronectin concentrations in lung lavage fluid after inhalation exposure to low levels of metals

Groups of rabbits were exposed by inhalation to chlorides of cobalt, nickel, and manganese as well as to tri- and hexavalent chromium at metal concentrations ranging from 0.4 to 3.9 mg/m3 for 1-4 months (5 days/week, 6 hr/day). Fibronectin content and lysozyme (muramidase) activity in lavage fluid were measured after all treatments and in alveolar macrophages after treatment with nickel chloride. In the lavage fluid no marked changes were seen in fibronectin content and lysozyme activity after exposure to tri- or hexavalent chromium or manganese. Nickel exposure significantly decreased the lysozyme activity in the lavage fluid and in the macrophages whereas the fibronectin content was unchanged in the lavage fluid and significantly increased in the macrophages. Both fibronectin content and lysozyme activity were increased markedly in the lavage fluid after cobalt exposure.

Phagocytic and catabolic function of the reticuloendothelial system in dogs subjected to defibrinogenation.

Abstract There is evidence that the reticuloendothelial system (RES) serves as an important protective mechanism in disseminated intravascular coagulation. The influence of defibrinogenation on the RES is studied in this investigation. For this purpose dogs were defibrinogenated with Defibrase R — a thrombin-like enzyme from the venom of Bothrops atrox. The phagocytic and catabolic functions of the RES were tested by the use of a test substance of heat-aggregated human serum albumin labelled with 125 I. Defibrase R was given in three groups of dogs at the time when the RES function was tested, 1 hour and 2 hours before the test. A significant delay of both the phagocytic and the catabolic activity was seen with increasing time between defibrinogenation and the RES-test, indicating a block of the RES with fibrin/fibrinogen degradation products. The reasons for this are discussed.

Influence of Cancer Chemotherapy Treatment on the Reticuloendothelial System in the Rat

The phagocytic function of the reticuloendothelial system (RES) in the rat has been studied after the administration of cyclophosphamide, 5-fluorouracil or a combination of these drugs and vincristine. No impairment in the elimination of 125I-labelled microaggregated human serum albumin was found. A significant reduction in relative and total spleen weight was not paralleled by a decreased splenic uptake of the RES test substance per gram tissue. A significant increase in the relative weight of the lungs was paralleled by a significant increase in the uptake of test substance on a per gram basis. No correr. A general reduction in the cell population of the haematopoietic system has to be assumed. If this reduction is more pronounced in subpopulations of T lymphocytes (suppressor T cells) has to be further tested.

Fibronectin increases the motility, phagocytosis and NBT-(nitroblue tetrazolium) reduction of granulocytes

Neutrophilic granulocytes preincubated in vitro with human plasma fibronectin (0-1.25 mg/ml) for 30 minutes showed increased spontaneous and chemotactic migration, increased uptake of fluorescein labelled yeast particles as well as higher NBT-reduction both with and without E. coli stimulation. These effects on the granulocyte functions were found to be mainly dose dependent. In control experiments, no significant effects were noted when fibronectin was replaced by human serum albumin in the same concentration range.

Plasma Fibronectin is Initially Decreased during Septicemia

Plasma fibronectin (PFN) levels were measured by radioimmunoassay in 24 normals and serially in 24 septic patients without underlying major trauma. All patients responded promptly to antibiotic therapy and none developed signs of shock or disseminated intravascular coagulation (DIC). After an initial decrease in PFN registered in most of the septic patients, the levels were normalized within 2 weeks of antibiotic treatment. The mean nadir levels of PFN were decreased (p less than 0.001) both in patients with gram-negative and gram-positive etiologies compared to the control group. Furthermore, the mean PFN value of the gram-positive group was lower (p less than 0.05) than that of the gram-negative group. It is concluded that a transient depletion of PFN is a constant finding in septic patients with a favourable outcome and that a single low PFN level alone does not justify fibronectin replacement therapy nor does it indicate a poor prognosis.