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At least 1,063 records · Page 59Linked to original sources
PubMed1990

Effects of different plasma substitutes on plasma fibronectin concentrations in patients undergoing abdominal surgery.

Plasma fibronectin is important for host defences as an opsonin of the mononuclear phagocyte system (MPS). The effects of three types of plasma substitutes, crystalloid, gelatin and dextran solutions, on plasma fibronectin levels were studied in patients undergoing abdominal surgery in relation to serum total protein and serum C-reactive protein (CRP) levels. Plasma fibronectin levels decreased during induction of anaesthesia and infusion of an electrolyte solution before infusion of the plasma substitute, and they were further decreased during operation after infusion of plasma substitutes and remained depressed on the first postoperative day in all study groups (P less than 0.05-0.01). In the crystalloid and dextran groups, plasma fibronectin levels exceeded preoperative levels by the 4th-5th postoperative day (P less than 0.05-0.01), but in the gelatin solution group they remained depressed (P less than 0.01). Serum total protein levels remained lower than preoperative values throughout the study period (P less than 0.05-0.01), whereas CRP levels were many times higher on days 1 and 4-5 postoperatively in all groups (P less than 0.01).

Abdomen↗
PubMed1983

A competitive inhibition assay for gelatin binding fibronectin.

A competitive inhibition assay for functional fibronectin (Fn), based on ELISA technology, is described. The assay measures Fn's physiologic ability to bind to denatured collagen (gelatin). Affinity-purified Fn inhibits the binding of alkaline phosphatase coupled Fn to gelatin-coated wells of a microtiter plate in a concentration-dependent manner. The assay range is 50-500 micrograms Fn/ml, which is suitable for the measurement of plasma Fn in both normal and opsonin deficient individuals. It is reproducible over an eightfold dilution of plasma and is resistant to interference by normal plasma proteins. The assay described is quick, quantitative, and reproducible, and satisfies the need for a measure of functional Fn activity in the clinical laboratory.

Blood Preservation↗
PubMed1984

Inactivation of hepatitis B and Hutchinson strain non-A, non-B hepatitis viruses by exposure to Tween 80 and ether.

Titrated stocks of hepatitis B virus and Hutchinson strain non-A, non-B hepatitis virus were diluted in normal serum to contain, respectively, greater than or equal to 10(6) and greater than or equal to 10(4) chimpanzee infectious doses (CID50) per milliliter and exposed to 1% Tween 80 and 20% ether at 4 degrees C for 18 h. After evaporation of the ether, the treated sera were each inoculated into two chimpanzees. The animals remained free of serologic and biochemical evidence of hepatitis during a 6-month follow-up period, and were then shown to be susceptible to infection by challenge with the original untreated inocula. To assess the effect of exposure to Tween 80/ether on coagulation factors, four lots of antihemophilic factor (AHF) concentrate and 2 lots of commercial factor IX concentrate were treated as above. For the AHF concentrate there was an average of 70% recovery of factor VIII procoagulant activity, 93% recovery of factor VIII-related antigen, and 73% recovery of fibronectin opsonin activity and no detectable change in ristocetin cofactor activity or in fibronectin antigen. Crossed immunoelectrophoresis revealed no change in migration rate of fibrinogen, fibronectin, and von Willebrand factor (vWF), although the quantity of fibrinogen was reduced. Factor VIII procoagulant activity and vWF activity remained associated during chromatography on BioGel A15.

Animals↗
PubMed1989

Bovine uterine defense mechanisms: a review.

Bovine uterine defense mechanisms during physiological and pathological conditions have been reviewed in this article. The initial uterine defense against bacterial infection is phagocytosis by uterine leucocytes (mainly neutrophils). The reported literature showed that very little work has been done on immunoglobulins and their role in the bovine uterine defense mechanisms; however, some investigators have found a positive correlation between gamma-globulin and the development of uterine infection after calving. Many explanations exist for the difference in susceptibility of the uterus to infection during the different phases of estrous cycle; however, most of the reports agreed that the uterine defense mechanism is inadequate during diestrus. The abnormal puerperium effects uterine defense mechanisms adversely and prolongs the time to complete uterine involution. Future treatment may utilise natural antimicrobial substances such as proteins or peptides derived from PMN, chemoattractant substances such as E. coli lipopolysaccharide or a bacteria-free filtrate of streptococci. Specific hyperimmunserum could also be used as opsonin for refractory cases of uterine bacterial infections.

Animals↗
PubMed1994

Plasma fibronectin levels in extremely preterm infants in the first 8 weeks of life.

Fibronectin has in the past been considered to function simply as a non-specific plasma opsonin. However, recent studies have demonstrated that this molecule plays an important role in fundamental components of the immune response, for example, neutrophil adhesion, T cell activation and endothelial function. Additionally, fibronectin is important in lung homeostasis where it contributes to alveolar epithelial integrity. In this study plasma fibronectin levels were measured longitudinally in a group of extremely preterm infants, mean gestational age 27 weeks. Plasma fibronectin levels at birth were significantly lower in the preterm study group than in term controls (mean 91 +/- 33 micrograms/mL compared with 214 +/- 62 micrograms/mL in the term controls, P < 0.0001). The preterm cohort demonstrated a more than two-fold rise in plasma fibronectin on days one and two; levels fell almost to baseline values by day three with a subsequent slow rise to a plateau by day 28. No further increase was seen by day 56. This sequence of early changes in fibronectin levels mirrored closely the time course of respiratory distress syndrome. Infants of mothers with pre-eclampsia had significantly lower peak fibronectin levels than in those without (P = 0.016), and those infants with bronchopulmonary dysplasia showed a trend towards lower basal fibronectin levels (P = 0.07) and a greater difference between peak and basal levels (P = 0.05). Neonates, particularly those born preterm, have blunted immunological responses to infection. Fibronectin plays a key role in immunological responsiveness. The significant changes in fibronectin levels after birth in the preterm neonate are likely to have important pathophysiological consequences.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1984

Isolation of membrane attack complex of complement from myelin membranes treated with serum complement.

The interaction between complement and myelin membranes and its possible role in myelin damage and in the disposal of damaged myelin in vivo is of interest because activation of complement generates both opsonin(s) and membrane attack complex of complement. In our studies on the role of complement in demyelination, we have shown that isolated myelin activates serum complement in the absence of myelin-specific antibody and that membrane attack complex of complement is the required factor in antibody-mediated demyelination of mouse cerebellar explant cultures. In the present study, we examined whether activation of serum complement by myelin is associated with the formation of membrane attack complex of complement in myelin membranes. Extracts of myelin-associated proteins following incubation of myelin with fresh serum were studied by ultracentrifugation on a sucrose density gradient for detection of C5b-9 neoantigen. The subunit structure of C5b-9 was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotting, and immunostaining. Results indicate that the macromolecular complex consisting of late-acting complement components, C5-C9, was assembled in the target myelin membranes.

Animals↗
PubMed1998

Macrophages recognize and adhere to an OmpD-like protein of Salmonella typhimurium.

Murine peritoneal macrophages bind to Salmonella typhimurium in vitro in the absence of exogenous opsonins. We have identified an outer membrane protein of S. typhimurium that mediates this adhesion. Biotin-labeled macrophages were used to probe electroblotted envelope proteins of S. typhimurium that had been previously resolved by polyacrylamide electrophoresis under denaturing and reducing conditions. Macrophages bound to an outer membrane protein with an apparent molecular mass of 44 kDa. The protein was purified to homogeneity and free of detectable lipopolysaccharide. Limited microsequencing of this protein resulted in a 15-amino acid query sequence of A-E-V-Y-N-K-D-G-N-K-L-D-L-Y-G, which shares complete identity with a 15-mer of both the OmpD of S. typhimurium SH 7454 and the OmpC polypeptide of Escherichia coli K-12. Picomolar concentrations of this purified protein significantly inhibited the subsequent adherence of 35S-labeled S. typhimurium to macrophages in monolayers. We propose that this 44-kDa protein is involved in the recognition of S. typhimurium by macrophage during the initial stages of infection.

Amino Acid Sequence↗
PubMed1995

In vitro cleavage of serum complement protein C3: a comparison between patients with adult periodontitis and periodontally healthy persons.

This study tested the hypothesis that in vitro cleavage of C3 could be triggered with similar case in serum samples from patients with adult periodontitis (n = 26) as in samples from periodontally healthy subjects (n = 13). A lipoteichoic acid, a lipopolysaccharide and an aggregated IgG served as activators of complement. On the average, the periodontitis group generated significantly (p < 0.01) more C3d activation fragments than did the healthy group, as judged from rocket immunoelectrophoresis measurements. Cleavage of C4 and factor B were then assayed through immunoblotting, without prior purification of the sera. C4c fragments were seen in all activated samples, the healthy group causing significantly (p < 0.05) more C4 conversion than did the periodontitis group. Cleavage of factor B, taken as a measure of soluble amplification convertase formation, was about equal between the groups. We inferred therefore that the 2 groups produced comparable amounts of C3b. The results suggested, however, that periodontitis sera favour breakdown of the opsonin C3b, most likely by activating the regulatory proteins factor H and I. Lipoteichoic acid, causing moderate depletion of C4 and factor B, produced significantly (p < 0.01) more C3d fragments than the other two activators examined. It may be that complement activation is down-regulated in periodontitis sera, perhaps at the expense of adequate local opsonic function.

Adult↗
PubMed1983

Elimination of allogeneic lymphocytes by mice.

Two major classes of response to allogeneic lymphocytes can be detected in mice in vivo, based on injecting them intravenously with 51Cr-labelled lymph node cells and examining them in a short term assay. A natural immunity discriminating between allogeneic and syngeneic lymphocytes is seen in the lymph nodes (and to a lesser extent, the spleen), which has such close similarities to natural cell-mediated responses of the NK class as thymic-independence and radioresistance. However, it has immunological specificity of a conventional kind, probably towards serologically determined K/D antigens. There is also an active immune response, produced by immunisation with dissociated lymphoid cells or allografting, which consists of three elements: an IgG opsonising alloantibody response, diverting circulating lymphocytes to the liver; an IgM opsonin, localising them to the spleen; and a cell-mediated serum-dependent elimination mechanism that destroys cells entering the lymph nodes and spleen. Dose-response curves for the primary response show evidence of high-dose paralysis of elimination. Dose-time-response results for the secondary show a variety of unique characteristics; evidence is presented to suggest that several aspects of the phenomenon betray primitive features retained from an earlier stage in the evolution of the immunological system.

Animals↗
PubMed1981

Fibronectin.

The current knowledge of the structure, expression and functions and fibronectin is reviewed. Fibronectin is a high molecular glycoprotein present in the blood, connective tissue and at cell surface. It is synthesized by many types of differentiated cells and is believed to be involved in the attachment of cells to the surrounding extracellular matrix. Fibronectin has affinity to the other main components of extracellular matrix, collagen and glycosaminoglycans. It also interacts with cell surfaces as shown by the fact that fibronectin-collagen complexes, or fibronectin alone when insolubilized on a surface such as plastic, enhances the attachment of various types of cells to such surfaces. It seems that fibronectin, through its binding to collagen and to the cell surface, forms a bridge between the cell and its surrounding matrix. Circulating fibronectin may participate in the formation of extracellular matrix in tissues. It may also function as a nonspecific opsonin design to facilitate the uptake of tissue debris by phagocytic cells. Studies aimed at elucidating the significance of fibronectin in physiological phenomena and in disease have only just begun. The abundance of fibronectin in basement membrane structures and the development changes observed in its expression lead one to believe that the attachment (or lack of it) of cells to fibronectin plays a significant role in morphogenetic events or in normal development. Malignantly transformed cells tend to lack cell-associated fibronectin. The significance of the lack of surface fibronectin in transformed cells is a matter of some controversy, but it fibronectin is indeed the main mechanism that anchors cells to the extracellular matrix, disturbances of this mechanism could play an important role in malignancy and many other diseases.

Cells↗
PubMed1984

Increased luminol enhanced chemiluminescence from peripheral granulocytes in juvenile periodontitis.

The granulocyte function in patients with juvenile periodontitis (JP) (eight men and six women, aged 13-33 yr) and sex and age matched controls was determined by the luminol enhanced chemiluminescence (CL) induced by opsonized and unopsonized bacteria or latex beads. Maximal CL induced by latex beads with or without autologus serum did not differ between the two groups. However, bacteria with or without autologous serum seemed to induce a higher maximal CL in the JP group. The difference was statistically significant for the results obtained with opsonized bacteria. Serum opsonized bacteria induced a much higher maximal CL than the unopsonized. The opsonin dependent reaction indicates a close association with the process of phagocytosis. The increased CL of granulocytes in JP could indicate the formation of extracellularly free oxygen radicals with the potential to damage tissue. These observations support a possible involvement of the granulocytes in the pathogenesis of JP.

Adolescent↗
PubMed1999

Functional differentiation of acute myeloid leukaemia blast cells.

Little is known of the functional status of blast cells from patients with acute myeloid leukaemia (AML). We have studied phagocytosis and membrane receptors by flow cytometry (FCM), and secretory activities in blast cells from 24 AML patients prior to treatment. Blast cells from 11/16 patients attached N. meningitidis, and internalization occurred in 7/14. The phagocytosis of zymosan particles and N. meningitidis correlated linearly (r = 0.9, p<0.01, n = 11). Surface membrane expression of CD32 and CD11b was sufficient to account for opsonin-dependent attachment in all except one patient. A significant fraction of the blast cells attached, but did not internalize meningococci. CD32 and CD11b were non-functional in all the blasts from five patients, and in a subpopulation from seven additional patients. Significantly more large than small blasts expressed CD32, CD35 and CD11b (p<0.001). Phagocytosis was unrelated to the secretion of IL-1alpha, IL-1beta, and TNFalpha. In conclusion, AML blast cell function is related to receptor expression, cell size and granularity, and to FAB-type.

Adult↗
PubMed1985

The status of pulmonary host defense in the neonatal sheep: cellular and humoral aspects.

In consideration of the sheep neonate as a compromised host, we have examined the status of cellular and humoral pulmonary host defense components at selected developmental time points. The dynamic character of the early neonatal LFC population, reflected in changes in subpopulations and proliferative capacity, most probably contributed to the observed changes in in vitro cell function. While certain cell responses, e.g., blood and LFC PMN chemotaxis, appeared intact by day 1, others developed subsequently. The ability of AMs to elaborate a chemotactic factor(s) was first noted at day 21. Bacteria binding and killing presented a biphasic maturation pattern, with full competence not present until day 180. Although the in vitro binding and killing activity of day 8 LFCs was comparable to that of the adult, it may be a poor indicator of in vivo host defense capacity, given the relative paucity of endogenous opsonins at that age. In fact, the interdependence of mediators suggests that the sheep neonate may remain a compromised host during the first 3 months of life. Thereafter, cellular and humoral parameters begin to approximate those of adult sheep and by 180 days of life pulmonary defense, as assessed in this study, is fully developed.

Age Factors↗
PubMed2003

Activation of complement in the central nervous system: roles in neurodegeneration and neuroprotection.

The complement system is an essential effector of the humoral and cellular immunity involved in cytolysis and immune/inflammatory responses. Complement participates in host defense against pathogens by triggering the formation of the membrane attack complex. Complement opsonins (C1q, C3b, and iC3b) interact with surface complement receptors to promote phagocytosis, whereas complement anaphylatoxins C3a and C5a initiate local inflammatory responses that ultimately contribute to the protection and healing of the host. However, activation of complement to an inappropriate extent has been proposed to promote tissue injury. There is now compelling evidence that complement activation in the brain is a double-edged sword in that it can exert beneficial or detrimental effects depending on the pathophysiological context. This review focuses on the roles of the complement system in the pathogenesis of acute brain injury (cerebral ischemia and trauma) and chronic neurodegeneration (Alzheimer's disease). Because many effects of the complement appear to promote neuronal survival and tissue remodeling, directing activation of the complement system in the brain may provide a better therapeutic rationale than inhibiting it.

Alzheimer Disease↗
PubMed1981

Immunisation against experimental staphylococcal mastitis in sheep - effect of challenge with a heterologous strain of Staphylococcus aureus.

Ewes were immunised in late pregnancy with killed Staphylococcus aureus vaccines prepared from organisms grown either under in vitro (vaccine T) or in vivo (Vaccine V) cultural conditions; other ewes were immunised with a live S. aureus vaccine and a further group remained non-vaccinated controls. The animals given either of the killed vaccines developed highest titres of agglutinating antibody in serum; there were only trivial levels of agglutinating antibody in milk from ewes in each treatment group. Ewes immunised with the live vaccine developed significantly greater levels of opsonins in serum than did those immunised with the killed vaccines or non-immunised controls. At 30 to 35 days post-partum the ewes were challenged by intramammary infusion of one million S. aureus of a strain different to the vaccination strain. In 4 of the 5 control ewes this resulted in the development of acute mastitis and a precipitous decline in milk production, whereas there was a considerable degree of resistance recorded in animals in each of the vaccinated groups. On criteria of milk production data, bacteriological status of milk and clinical signs of acute mastitis it was apparent that animals which had been immunised with the live vaccine were better protected from challenge than those immunised with either killed vaccines T or V.

Animals↗
PubMed1995

A review of antimicrobial peptides: defensins and related cationic peptides.

Cationic antimicrobial peptides are present throughout the plant and animal kingdoms and bear striking structural and functional similarities across species lines. They provide primitive, nonspecific means of combating a variety of bacteria, fungi, enveloped viruses, and protozoa. Some are also cytotoxic against host cells, including neoplastic cells. Cationic antimicrobial peptides may play various roles in inflammation and tissue repair. Antimicrobial peptides are found in epithelial tissues regularly exposed to microbial attack as well as in cells whose primary function is defense against potential pathogens. They constitute an important part of the nonoxidative antimicrobial arsenal of leukocytes. They are preformed and/or readily synthesized when the cells are stimulated by exposure to pathogens. They exert their effects directly by inserting into membranes of target cells and forming ion channels which increase membrane permeability; however, antimicrobial peptides can also act as opsonins to facilitate phagocytosis. Resistance to defensins is a virulence factor for organisms such as Salmonella sp. The study of cationic antimicrobial peptides is increasing our understanding of innate immunity, inflammation, and the pathogenesis of genetic diseases such as specific granule disease in humans. Therapeutic applications of antimicrobial peptides are currently under investigation.

Journal Article↗
PubMed1989

[Production of oxygen free radicals by phagocytes in patients on hemodialysis].

In order to elucidate the vulnerability to infection in patients on chronic hemodialysis, as one of the host defense mechanisms, the production of oxygen free radicals by phagocytes was studied in patients by luminol- or lucigenine-enhanced chemiluminescence (CL). Whole blood CL of the patients, in both luminol- or lucigenine-enhanced was significantly higher than that in healthy adults after stimulation by zymosan, PMA, and Staphylococcus aureus (S. aureus) 209 P. However, the CL response of the patients' polymorphonuclear neutrophils (PMNs) with the same stimuli was slightly lower than that in healthy adults. There were no differences in the levels of opsonins, such as complements and immunoglobulins, between the patients and healthy adults. It appears that any factor in the patients' serum enhances CL response, because of the PMN CL response after addition of patients' serum was higher than that after addition of healthy controls' serum, and the PMN CL response after the addition of patients' serum obtained after hemodialysis was higher than that before hemodialysis. The addition of erythrocytes to PMNs from healthy adults caused a reduction in the PMN CL response, but the addition of urea and creatinine had no effect. The CL response induced by microsphere-bound luminol (lumisphere), which makes possible the direct measurement of highly reactive oxygen within phagosomes, was studied in the patients and controls. The CL response in the patients was slightly lower than those in controls, but not significant. These results suggest that not only CL response of phagocytes but also other defense mechanisms should be studied further to make clear the vulnerability to infection in these patients. In addition, the effect of three antibiotics, cefbuperazone, cefminox and latamoxef on luminol-enhanced CL of whole blood was studied in healthy adults and the patients. After 3-hour exposure to those drugs at subinhibitory concentration (1/4 MIC), Klebsiella pneumoniae (K. pneumoniae) 163 treated by drugs induced higher CL response of whole blood than that by untreated bacteria in both healthy adults and the patients, and the peak time of the CL response induced by the drug-treated bacteria was shorter than that by untreated bacteria. This study suggests that the three drugs at sub-MIC work in partnership with host defense against infection due to K. pneumoniae even in patients on chronic hemodialysis.

Adult↗
PubMed1993

[A human monoclonal antibody cocktail for experimental mouse infection with clinically isolated strains of Pseudomonas aeruginosa].

A human IgG monoclonal antibody cocktail against Pseudomonas aeruginosa serotypes A, B, E, G, I, and M (MCA5) was tested for its therapeutic effect on the infected mice with clinically isolated P. aeruginosa strains. More than 80% of the collected strains were found to belong to the above six serotypes. Direct agglutination with MCA5 gave slight reduced rates, but over 70% of the strains were agglutinated with MCA5. Fifty percent lethal doses of the representative strains to mice (LD50) were estimated, and 50% protective doses of MCA5 to the infected mice with 5 LD50 of the strains (ED50) were determined. MCA5 was found not to be protective to all the infected mice with above six serotypes but protective only to the mice infected with the agglutinated strains. Confirmation of the agglutination of the causative organism with MCA5 is required for the treatment by MCA5. ED50 for a clinically isolated strain and the virulent stock strain were determined under the various challenge doses. It was found that ED50 increased in parallel with the increase of challenged doses but did not change depending on the virulence of the infected strains. These results indicated that this cocktail worked as opsonin. Opsogenic anti-O IgG antibody could be most effective to protect the opportunistic infections caused by the bacteria which have not so powerful exotoxins.

Animals↗