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Biomedical subjects

B R Andersen

Publications and source records attributed to B R Andersen.

At least 37 records · Page 2Linked to original sources
PubMed1991

Analysis of neutrophil chemotaxis and CD11b expression in pre-pubertal periodontitis.

The objectives of this study were to (1) determine chemotaxis (CX) response by neutrophils (PMNs) isolated from patients with the localized form of pre-pubertal periodontitis (L-PP) and compare these responses with those of age-matched and adult controls, (2) determine the level and up-regulation of CD11b expression upon stimulation with fMLP by peripheral blood PMNs (PB-PMNs) isolated from patients with L-PP and compare these levels with those of age-matched and adult controls, and (3) determine whether there is a correlation between CX and CD11b expression (up-regulation) by PB-PMNs. PB-PMNs from a total of seven patients with L-PP, seven age-matched pediatric controls, and 11 adult controls (four adults for both CD11b and CX assays, and seven adults for CX assays only) were analyzed for CX and CD11b expression. Direct immunofluorescence staining of CD11b was performed with FITC-conjugated monoclonal antibody. Flow cytometry was used to analyze stained cells for their fluorescence intensity. Chemotaxis activity in response to 10(-8) mol/L fMLP was examined in micro-well chemotaxis chambers. The results indicated that CX of PMNs from both L-PP patients and pediatric control subjects was significantly decreased, compared with that of normal adult control subjects (p less than 0.001). There was no significant difference between CX of PMNs from L-PP patients and that from normal pediatric controls (p greater than 0.7). CD11b expression did not significantly differ among L-PP patients, normal pediatric controls, and adult controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effect of glucocorticoids and interferon-gamma on the oxidative responses of monocytes from leprosy patients and normal donors.

Leprosy patients suffering from erythema nodosum leprosum are frequently treated with glucocorticosteroids. The role glucocorticosteroids and interferon-gamma (IFN-gamma) play in regulating the interaction of phagocytic cells with Mycobacterium leprae was examined. Monocytes from leprosy patients receiving prednisone therapy responded to lower concentrations of IFN-gamma in vitro with enhanced superoxide anion release when challenged with M. leprae or M. bovis BCG than did monocytes from healthy subjects and other leprosy patients. Although the number of patients was small and the population heterogeneous, the data suggested that prednisone could alter IFN-gamma efficacy and led to the examination of the effect of glucocorticosteroids on IFN-gamma activation of monocytes. IFN-gamma treatment following in vitro dexamethasone pretreatment of monocytes from healthy subjects resulted in a greater enhancement of superoxide anion generation than that observed with IFN-gamma treatment alone. These findings are important considerations in evaluating patient immune function because IFN-gamma is being used in a number of clinical trials with leprosy patients.

Adult↗
PubMed1990

Killing of Mycobacterium tuberculosis by neutrophils: a nonoxidative process.

To determine the role of oxygen radicals in the killing of Mycobacterium tuberculosis by neutrophils, the effects of free-radical inhibitors and enzymes, catalase, superoxide dismutase, taurine, deferoxamine, and histidine were evaluated. Changes in the viability of M. tuberculosis were determined by agar plate colony counts and a radiometric assay. No impairment in killing was seen with any of the inhibitors or enzymes. Patients with chronic granulomatous disease (CGD) have a defect in the NADPH oxidase pathway, causing their neutrophils to be unable to generate oxygen radicals. If these radicals are involved in killing, then CGD neutrophils should be less effective killers of M. tuberculosis than normal neutrophils. There was no evidence by either measure of M. tuberculosis viability that CGD neutrophils were less bactericidal than normal neutrophils. Killing by normal neutrophils was also effective in the absence of serum. These results lead to the conclusion that the mechanism by which M. tuberculosis is killed by neutrophils is independent of the oxygen metabolic burst.

Catalase↗
PubMed1990

Effect of Mycobacterium leprae's phenolic glycolipid-I on interferon-gamma augmentation of monocyte oxidative responses.

Peripheral blood monocytes were pretreated with phenolic glycolipid-I (PGL-I), dimycocerosyl phthiocerol (DIM), or mycoside A, then cultured in the presence or absence of interferon-gamma (IFN-gamma). Their oxidative responses to Mycobacterium leprae, phorbol myristate acetate (PMA), and opsonized zymosan were evaluated. In response to M. leprae, monocytes pretreated with PGL-I released less O2- than nonlipid-treated control cells. The IFN-gamma augmentation of oxidative responses was suppressed only when in PGL-I-pretreated monocytes and only when the stimulus was M. leprae. This suggests that PGL-I, by affecting the IFN-gamma enhancement of phagocytic cell oxidative responses, aids further the intracellular survival of M. leprae.

Antigens, Bacterial↗
PubMed1990

A comparison of monocyte oxidative responses in leprosy patients and healthy subjects as influenced by mycobacterial lipid pretreatment.

Superoxide anion (O2-) release by monocytes from leprosy patients in a paired study was lower than that released by monocytes from healthy controls. Pretreatment of healthy control monocytes with phenolic glycolipid-I (PGL-I) of Mycobacterium leprae resulted in the release of less O2- than released by buffer-treated cells or cells pretreated with structurally similar lipids. However, pretreatment of patient monocytes with PGL-I did not affect the O2- generation, perhaps because the cells already had a lower capacity to produce O2-. Upon further examination of the data from the patient population, monocytes from lepromatous patients released significantly less O2- than cells from normal controls, while tuberculoid patient cells released O2- in amounts similar to that generated by cells from normal controls. In addition, monocytes from patients with a high bacterial index had a lower capacity to generate O2- when compared to cells from healthy individuals.

Adult↗
PubMed1989

Suppression of monocyte oxidative response by phenolic glycolipid I of Mycobacterium leprae.

Mycobacterium leprae synthesizes a unique phenolic glycolipid (PGL-I) in abundant quantities. We studied the effect of PGL-I on the generation of superoxide anion (O2-) by stimulated human monocytes. Peripheral blood monocytes pretreated with PGL-I released less O2- when stimulated with M. leprae than did control monocytes. Monocytes pretreated with dimycocerosyl phthiocerol, mycoside A of Mycobacterium kansasii, or mycoside B of Mycobacterium microti, on the other hand, released O2- in quantities comparable to control monocytes in response to M. leprae stimulation. Monocyte O2- release in response to other stimuli of the oxidative metabolic burst, such as PMA, zymosan, Mycobacterium bovis Bacille Calmette-Guérin, or M. kansasii, was unaffected by lipid pretreatment. These findings demonstrate that PGL-I has a direct effect on monocyte O2- generation in response to M. leprae and suggest that PGL-I is a modulator of phagocytic cell function.

Adjuvants, Immunologic↗
PubMed1988

Human phagocytic cell responses to Mycobacterium leprae and Mycobacterium bovis Bacillus Calmette-Guérin. An in vitro comparison of leprosy vaccine components.

Components of current vaccines for Hansen's disease include Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and killed Mycobacterium leprae. BCG infections in humans are rare and most often occur in immune-compromised individuals. M. leprae on the other hand, although not causing clinical disease in most exposed individuals, is capable of infecting and replicating within mononuclear phagocytes. Lymphocytes from patients with the lepromatous form of Hansen's disease exhibit defective lymphokine production when challenged in vitro with M. leprae. This may result in inefficient mononuclear phagocyte activation for oxidative killing. To study the ability of normal phagocytes to ingest and respond oxidatively to BCG and M. leprae, we measured phagocytic cell O2- release and fluorescent oxidative product formation and visually confirmed the ingestion of the organisms. BCG stimulated a vigorous O2- generation in neutrophils and monocytes and flow cytometric oxidative product generation by neutrophils occurred in the majority of cells. M. leprae, stimulated a weak but significant O2- release requiring a high concentration of organisms and long exposure. By flow cytometric analysis, most neutrophils were able to respond to both organisms with the generation of fluorescent oxidative products. Neutrophil oxidative responses to M. leprae were substantially less than responses seen from neutrophils exposed to BCG. By microscopic examination of neutrophils phagocytizing FITC-labeled bacteria, it was shown that both M. leprae and BCG were slowly ingested but that more BCG appeared to be associated with the cell membrane of more of the cells. When phagocytic cells were incubated with BCG and M. leprae for 30 min and subsequently examined by electron microscopy, few organisms were seen in either neutrophils or monocytes. This suggests that BCG are easily recognized and slowly ingested by normal phagocytic cells, the majority of which respond with a strong oxidative burst. M. leprae appeared to only weakly stimulate phagocyte oxidative responses and were also slowly phagocytized.

Adult↗
PubMed1988

Rapid visualization of Acanthamoeba using fluorescein-conjugated lectins.

We investigated the efficacy of fluorescein-conjugated lectins (FCLs) for the rapid visualization of Acanthamoeba species. Cultures of Acanthamoeba castellani, Acanthamoeba culbertsoni, and Acanthamoeba polyphaga were established on nonnutrient agar plates supplemented with Escherichia coli. Maximal trophozoite populations were established four to five days after initial subculturing; mature cysts were routinely noted three to six days later. At various time points, trophozoites and/or cysts were harvested and suspended in Page's saline. Following a previously described protocol, samples of the suspensions were placed on glass slides and incubated with one of a panel of 14 FCLs. At the end of the incubation period, the slides were examined using an epifluorescence microscope. Concanavalin A brightly stained both cysts and trophozoites. Wheat germ agglutinin brightly stained cysts but only minimally stained trophozoites. These results suggest that FCLs may be useful for rapid visualization of Acanthamoeba organisms in corneal infections.

Acanthamoeba↗
PubMed1988

Effect of Mycobacterium tuberculosis-derived sulfolipid I on human phagocytic cells.

Experiments were performed to determine the effects of Mycobacterium tuberculosis-derived sulfolipid I on phagocytic cells. Sulfolipid I was taken up in significant amounts by human neutrophils and in lesser amounts by monocytes and lymphocytes. Superoxide (O2-) production by neutrophils was significantly increased by sulfolipid I, but the rate of production was slower than that reported previously for other stimuli. The optimal concentration of sulfolipid I for stimulation of O2- production was 27 micrograms/ml, while higher concentrations produced less. At substimulatory levels sulfolipid I caused enhancement of O2- release from neutrophils when it was subsequently stimulated by other agents. Nonadherent monocytes from most normal donors failed to produce O2- when treated with sulfolipid I; however, adherent monocytes pretreated with gamma interferon did produce O2- with sulfolipid I stimulation. Priming for an enhanced oxidative response of activated monocytes was also observed. These sulfolipid I-induced changes in phagocytic cell function may be important in altering the ability of phagocytes to respond effectively to M. tuberculosis and may also cause exaggerated inflammatory responses.

Cell Survival↗
PubMed1987

Rhinitis, pneumonia, and defective neutrophil function in the Doberman pinscher.

Eight closely related Doberman Pinschers with chronic rhinitis and pneumonia had normal or increased numbers of structurally normal leukocytes. Serum concentrations of immunoglobulins and complement were above or within normal ranges. Lymphocyte transformation indices for 3 mitogens were normal in 7 of the 8 dogs; the remaining dog had low values for all mitogens. Neutrophils phagocytized bacteria normally, but had impaired bactericidal ability. The bactericidal defect may have been related to the inability of neutrophils to generate normal numbers of oxygen radicals after stimulation, as determined by decreased ability of neutrophils to reduce nitroblue tetrazolium and to produce superoxide following opsonized zymosan stimulation. These observations, plus finding chronic inflammatory disease in the lungs of one dog, indicated that the disease may have some similarity to chronic granulomatous disease or to complement receptor deficiency in man.

Animals↗
PubMed1986

Mycobacterium leprae fails to stimulate phagocytic cell superoxide anion generation.

Mycobacterium leprae is an intracellular pathogen that is ingested by and proliferates within cells of the monocyte/macrophage series. Mechanisms by which intracellular pathogens resist destruction may involve failure to elicit a phagocyte "respiratory burst" or resistance to toxic oxygen derivatives and lysosomal enzymes. We have studied the ability of M. leprae and Mycobacterium bovis BCG to stimulate the generation of superoxide anion (O2-) in vitro by human blood neutrophils and monocytes and murine peritoneal macrophages. M. leprae bacteria failed to stimulate significant O2- release except at high bacteria-to-cell ratios (greater than 50:1) whether or not they were pretreated with normal serum or serum from patients with lepromatous leprosy. Either viable or irradiated BCG; on the other hand, stimulated the three cell types to release significant amounts of O2- when challenged with as few as 10 organisms per cell. Serum pretreatment enhanced the release of O2- by the three cell types. Preincubation for 18 h with viable M. leprae did not inhibit the ability of monocytes to respond with an oxidative burst to phagocytic stimuli. The failure of M. leprae to stimulate phagocyte O2- generation may be an important factor in its pathogenicity.

Animals↗
PubMed1985

Canine neutrophil plasma membrane markers.

The purpose of this investigation was to determine which enzyme activities are true canine neutrophil plasma membrane markers. Three enzymes thought to be present on plasma membranes were chosen for study: 5'-nucleotidase, magnesium-dependent adenosine triphosphatase (Mg2+-ATPase), and leucine aminopeptidase. Both 5'-nucleotidase and Mg2+-ATPase were found to be ectoenzymes in the canine neutrophil but additional Mg2+-ATPase activity was located intracellularly. An endogenous inhibitor of 5'-nucleotidase was found in the cytosol of canine neutrophils. The specific 5'-nucleotidase inhibitor, adenosine 5'-[alpha, beta-methylene] diphosphate also inhibited the canine enzyme in intact cells. Leucine aminopeptidase was located solely in the myeloperoxidase-containing granules of the canine neutrophil. Plasma membrane, as identified by the presence of Mg2+-ATPase and 5'-nucleotidase activities, was separated from other cell organelles by Percoll-density gradient centrifugation of a 10 000 X g supernatant of nitrogen cavitated neutrophils.

5'-Nucleotidase↗
PubMed1985

Isolation of canine neutrophil plasma membranes.

This paper describes the isolation of plasma membrane vesicles formed by nitrogen cavitation of canine neutrophils. Plasma membranes from disrupted cells were separated from other membranes and organelles by Percoll-density gradient centrifugation. Transmission electron microscopic examination of membrane preparations chromatographed on either Sephacryl S-1000 or Sepharose 4B revealed that two populations of plasma membrane vesicles were formed: large (176 +/- 22nm), and small (119 +/- 11nm). Purified large vesicles were separated from Percoll and contaminating cytosol by Sephacryl S-1000 chromatography. Small vesicles were obtained free of Percoll by recavitating purified large vesicles. Problems encountered due to the presence of a soluble 5'-nucleotidase inhibitor also are discussed. Large and small membrane vesicles were separated into adherent and non-adherent populations by affinity chromatography on either concanavalin A-Sepharose or lentil lectin-Sepharose columns.

5'-Nucleotidase↗