PubMed Health⌕ Search

Biomedical subjects

D Befus

Publications and source records attributed to D Befus.

At least 19 recordsLinked to original sources
PubMed1992

Inhibition of neutrophil chemotaxis and activation following decentralization of the superior cervical ganglia.

Recent studies have shown that bilateral decentralization (sympathectomy) of the superior cervical ganglia (SCG) of rats sensitized to the parasite Nippostrongylus brasiliensis attenuated the development of pulmonary inflammation following allergen challenge. Sympathectomy inhibited total leukocyte infiltration into lung lavage fluids, particularly neutrophil infiltration. To define the effects of decentralization of the SCG on neutrophil responses, peripheral blood neutrophils of rats were isolated and tested in in vitro chemotaxis and phagocytosis assays. Neutrophils from rats that were sympathectomized 7 days previously displayed a marked reduction in chemotaxis to N-formyl-methionyl-leucyl-phenylalanine and leukotriene B4 compared to neutrophils from sham-operated or unoperated groups. Although the degree of chemotaxis was greater in blood neutrophils from parasite-infected rats than from uninfected rats, sympathectomy markedly reduced the chemotactic responses of both groups. In addition, neutrophils of sympathectomized rats were unresponsive to lipopolysaccharide-induced metabolic activation as assessed by in vitro phagocytosis and oxidative reduction of nitroblue tetrazolium. Thus, decentralization of the SCG of rats affects the chemotactic responses and functions of neutrophils. Understanding the role of the sympathetic nervous system in modulating the behavior of neutrophils will shed light on the interactions between the nervous and immune systems.

Animals↗
PubMed1992

Role for the submandibular gland in modulating pulmonary inflammation following induction of systemic anaphylaxis.

Previous studies have shown that bilateral decentralization of the superior cervical ganglia (SCG; decentralization) attenuates allergen-induced pulmonary inflammatory responses in male rats sensitized to the nematode Nippostrongylus brasiliensis. The present report examines the neuronal and glandular mechanisms mediating the protection against pulmonary inflammation afforded by decentralization. Tissues and organs innervated by the SCG are responsible for this protection since, in a manner similar to decentralization, bilateral removal of the SCG (ganglionectomy) reduced anaphylaxis-induced accumulation of inflammatory cells in bronchoalveolar lavage fluid. Removal of the submandibular gland (sialadenectomy) did not modify the severity of the pulmonary inflammation, but concurrent sialadenectomy and decentralization abolished the protective effect of decentralization. Thus, we postulate that cervical sympathetic nerves tonically inhibit release of anti-inflammatory factors from submandibular glands. No relationship was found between noradrenaline and serotonin content of submandibular glands and the degree of protection against pulmonary inflammation offered by decentralization and ganglionectomy. Both decentralization and ganglionectomy appeared to increase the level of transcripts that encode immunomodulatory growth factors (nerve growth factor and epidermal growth factor) in submandibular glands, but these denervations evidently did not modify the transcripts for TGF beta 2. Systemic inflammatory events are regulated by the central nervous system at a level superior to the SCG probably through modulation of immunoregulatory factors in submandibular glands.

Anaphylaxis↗
PubMed1992

Mast cell response to formaldehyde. 1. Modulation of mediator release.

To examine the effects of the atmospheric pollutant formaldehyde on functionally distinct mast cells, peritoneal mast cells (PMC), intestinal mucosal mast cells (IMMC) and mouse bone-marrow-derived mast cells (BMMC) were incubated with various concentrations of formaldehyde. Pretreatment for 30 min with up to 100 micrograms/ml formaldehyde was not cytotoxic to mast cells. Formaldehyde (1-10 micrograms/ml) alone induced low levels of histamine release (< 10%) from IMMC and BMMC. Antigen-induced histamine release was significantly increased in both PMC pretreated with low concentrations of formaldehyde (5-20 micrograms/ml) and BMMC pretreated with 10 micrograms/ml formaldehyde but decreased in PMC pretreated with a higher concentration (100 micrograms/ml) of formaldehyde. By contrast, antigen-induced histamine release was decreased in IMMC pretreated with formaldehyde in a dose-dependent manner. Histamine release stimulated with A23187 was also increased in PMC pretreated with a low concentration (10 micrograms/ml) of formaldehyde but decreased in those pretreated with a higher concentration (100 micrograms/ml) of formaldehyde. Pretreatment with 10 micrograms/ml formaldehyde significantly enhanced beta-hexosaminidase release from PMC stimulated with antigen or A23187. Compared to sham-treated PMC, PMC pretreated with formaldehyde expressed a markedly depressed natural cytotoxicity for the tumor target WEHI-164 (an assay of tumor necrosis factor alpha activity). These results suggest that formaldehyde modifies various mast cell functions through alterations in cellular metabolism. Such effects may be important in respiratory and other diseases associated with formaldehyde exposure.

Animals↗
PubMed1992

Mast cell response to formaldehyde. 2. Induction of stress-like proteins.

Previously we established that immediately after pretreatment with low concentrations (5-10 micrograms/ml) of formaldehyde antigen- and ionophore-induced histamine secretion was enhanced from peritoneal mast cells (PMC) isolated from rats infected with Nippostrongylus brasiliensis. In contrast to immediately following pretreatment with low concentrations of formaldehyde, 3 h after a 30-min treatment with formaldehyde (10, 50 and 100 micrograms/ml) antigen-induced histamine secretion from PMC was significantly depressed, and 35S-methionine incorporation was also decreased. To further explore the effects of formaldehyde on mast cells, we investigated protein biosynthesis of PMC following formaldehyde treatment and compared this with the effects of hydrogen peroxide (H2O2) or heat treatment. One- and two-dimensional SDS-PAGE were used to assess the effects. Formaldehyde treatment induced the synthesis of 70- and 72-kD stress-like proteins in rat PMC. Pretreatment of PMC with 50 microM H2O2 and heat (45 degrees C) also induced proteins with the same molecular weight. Two-dimensional SDS-PAGE analysis established that formaldehyde-induced 70-kD proteins had the same pI values as 70-kD heat shock proteins previously observed in mammalian cells. These results suggest that formaldehyde, H2O2 and heat shock induce stress proteins in rat PMC. It will be important to establish whether or not these stress proteins are responsible for the functional alterations observed in the mast cells.

Animals↗
PubMed1991

Mast cell heterogeneity: protein composition, biosynthesis and mRNA characterization.

Proteins of rat peritoneal mast cells (PMC), rat intestinal mast cells (IMMC) and human skin mast cells (SMC) were compared by two-dimensional electrophoresis. PMC and IMMC had many similarities in distribution of their neutral/acidic proteins but marked differences in the more abundant, granule-associated basic proteins. SMC proteins showed a unique distribution. Distributions of the products of in vitro translation of PMC and IMMC RNA were different from those of proteins isolated directly from these cells which, together with results of pulse-chase labelling experiments, shows evidence for processing of certain mast cell proteins including rat mast cell proteases I and II.

Humans↗
PubMed1991

Pathology of pulmonary parasitic migration: morphological and bronchoalveolar cellular responses following Nippostrongylus brasiliensis infection in rats.

Nippostrongylus brasiliensis has an obligatory migratory phase through the lungs during its development in rats. This migration is associated with marked tissue damage and pronounced cellular reaction. Given that cells from the lower respiratory tract, especially alveolar macrophages, can adhere to and kill larvae of N. brasiliensis in vitro, we studied the time course of morphological changes associated with parasitic migration. Compared to a primary infection, a secondary infection resulted in significant changes in the pulmonary tissue characterized by an early acute inflammation leading to granulomatous reaction in the parenchyma and a leucocytosis in the bronchoalveolar lavage fluids with an anamnestic increase in absolute numbers of neutrophils, alveolar macrophages, eosinophils, and lymphocytes. Scanning electron microscopy showed that inflammatory cells, especially alveolar macrophages, granulocytes, lymphocytes, erythrocytes, and platelets, adhered to the larvae following secondary infection and this adhesion was associated with disruption of cuticular surface in some larvae. Secondary infection also resulted in retention of larvae in granulomatous lesions in the lungs even up to 21 days postinfection. There was mast cell and type II pneumocyte hyperplasia and these cells appeared to be activated. Thus, the histopathological changes in lungs correlated with the bronchoalveolar cellular responses and further document the inflammatory and immunological reactions during the migration of N. brasiliensis larvae.

Animals↗
PubMed1990

Marked antiinflammatory effects of decentralization of the superior cervical ganglia.

Intravenous challenge with parasite antigens in Nippostrongylus brasiliensis-sensitized rats resulted in anaphylactic shock and, in some animals, death. Surviving animals showed significant drop in mean arterial blood pressure, cardiac output, and blood flow to the trachea, bronchioles, and mesentery. After anaphylaxis, changes in the cellular and protein composition in bronchoalveolar lavage fluids (BALF) were assessed. 8 h after antigen challenge, there was significant influx of inflammatory cells and an increase in the levels of histamine and serum-derived immunoglobulins (IgG and IgM) in BALF. Chemotactic activity for neutrophils was also present in BALF. Once we established this anaphylaxis-induced model of pulmonary inflammation, we sought to determine whether or not the superior cervical ganglia (SCG) modulate this inflammation. We performed bilateral superior cervical ganglionectomy or decentralization of the SCG. Our results show that decentralization significantly reduced mortality (by 68%) after anaphylaxis. Furthermore, the increases in levels of serum-derived proteins, histamine, and influx of cells (especially neutrophils) observed in BALF after anaphylaxis were attenuated by both decentralization and ganglionectomy. By contrast, hemodynamic parameters in the respiratory tract and the presence of neutrophil chemotactic activity in BALF were not influenced by decentralization. Thus, the severity of pulmonary inflammation initiated by systemic anaphylaxis is depressed by bilateral ganglionectomy or decentralization of SCG.

Animals↗
PubMed1990

Characterization of rat tissue cultured mast cells.

Twelve continuous rat tissue cultured mast cell (MC) lines were established by prolonged culture of rat peritoneal MC in the absence of added factors or feeder layers. Two of these lines, RCMC1 and RCMC2, have been briefly described previously, seven others are now also described. Both RCMC1 and RCMC2 lack a marker chromosomes present on RBL-CA10.7 cells. All lines were found to express the phenotype of mucosal MC as defined by alcian blue-positive and safranin O-negative staining, the presence of rat MC protease II and a low histamine content. When analyzed for high-(Fc epsilon RI) and low-affinity (Fc epsilon RL) receptors for IgE, the various lines yielded a variety of receptor patterns. Northern blot analysis of the RNA of RCMC1, RCMC2 and RBL-CA10.7 revealed that all three cell lines contained the same mRNA species for the alpha, beta and gamma subunits for Fc epsilon RI previously found in another rat basophilic leukemia cell line. Quantitation of the relative amounts of alpha, beta and gamma mRNA did not correlate with the expression of the relative amounts of Fc epsilon RI(alpha) in these cells. The relative amounts of mRNA for all these subunits of RCMC2 were equal or higher than those of RCMC1, suggesting that the low expression of Fc epsilon RI(alpha) on the former was a consequence of post-transcriptional events. Analysis of a RCMC1 clone over a 6-month period revealed changes in the expression of both Fc epsilon RI(alpha) and Fc epsilon RL.

Animals↗
PubMed1990

Complement-mediated leucocyte adherence to newly excysted and 4-day-old Hymenolepis diminuta.

Four-day-old and newly excysted H. diminuta were exposed in vitro (37 degrees C; 5% CO2/air atmosphere) to serum and peritoneal cells (1.7-4.4 X 10(5] obtained from rats. Four-day-old worms incubated in serum alone were lysed in titres of less than 16. In assays containing peritoneal cells, leucocytes, predominantly eosinophils and macrophages, adhered to the posterior end of the parasite in serum titre 32, but not in serum titres 64 and 128. In this region of the worms phagocytosis of microtriches by macrophages, microthrix denudation and loss of tegument were noted. Serum-mediated lysis of newly excysted cysticercoids occurred at a serum titre of 64 and leucocyte adherence and phagocytosis of microtriches occurred in serum titres 128 and 256. Attachment of peritoneal cells to worms did not occur in assays containing heat-inactivated serum and it is suggested that regional leucocyte adherence and subsequent parasite damage is complement-mediated.

Animals↗
PubMed1990

Zoonotic potential of giardiasis in domestic ruminants.

This study was conducted to assess the prevalence and zoonotic potential of giardiasis in domestic ruminants. Prevalence of infection was 17.7% in sheep and 10.4% in cattle and was significantly higher in lambs and calves (35.6% and 27.7%, respectively). Naturally infected lambs released cysts intermittently for months. Giardia trophozoites from sheep had typical claw hammer-shaped median bodies and were successfully cultured in TYI-S-33 medium, and cytosolic, cytoskeletal, and membrane fractions exhibited protein profiles similar to human isolates (WB). Immunoblotting showed that sera from infected sheep recognized human Giardia, sera from patients with giardiasis recognized Giardia from sheep, and in both cases recognition involved antigenic proteins of similar molecular weight. Cyst output and clinical signs in ovine infection resemble human disease and the organisms infecting humans and ruminants are morphologically and antigenically similar. It is postulated that domestic ruminants may be a reservoir for human infection and vice versa, thus classifying giardiasis as a zooanthroponotic disease.

Alberta↗
PubMed1989

Loss of antigens from immunoblotting membranes.

Immunoblotting of PAGE-separated proteins is widely used. After electrophoretically transferring proteins from PAGE gels, sites on the membrane which are unoccupied are blocked or quenched with excess protein. The sensitivity of the immunoblotting technique is in part dependent on the amount of antigen associated with the membrane. We have investigated the loss of blotted proteins during blocking of various membranes with milk. Transblotted proteins are lost from nitrocellulose membranes (NC) (0.45 microns) in proportion to the amount of milk in the blocking solution and loss increases with time. When 5% milk was used as the blocking solution the amount lost was about 10% within 1 h and approached 25% at 24 h. This loss was nonselective and involved blotted antigens of a wide range of Mr. This time- and concentration-dependent relationship for the loss of transblotted proteins was tested with four immunoblotting membranes: Immobilon-P (Millipore), NitroPlus-2000 (MSI), and NC (0.2 microns and 0.45 microns pore size). NC (0.2 microns) gave the best results with the lowest percentage loss at 1 h (less than 5%). We recommend using NC (0.2 microns) and blocking with 0.5% milk for 30 min to minimize the loss of antigens from immunoblotting membranes.

Animals↗
PubMed1989

Isolation and characterization of IgE receptors from rat intestinal mucosal mast cells.

High-(Fc epsilon RI) and low-(Fc epsilon RII) affinity IgE receptors were isolated from surface radioiodinated, Nonidet-P40-solubilized rat intestinal mucosal mast cells (IMMC) and compared with those on rat peritoneal mast cells (PMC) and rat basophilic leukemia (RBL) cells. Fc epsilon RII were isolated by affinity chromatography using IgE-Sepharose or by anti-Fc epsilon RII antisera and protein A-Sepharose. The surface-exposed, IgE-binding alpha subunits of Fc epsilon RI [Fc epsilon RI alpha] were isolated by affinity chromatography using IgE and anti-IgE-Sepharose. Fc epsilon RI alpha on IMMC had an apparent molecular mass of 59 kDa, somewhat larger than that of PMC (51 kDa), RBL-2H3 cells (51 kDa) or RBL-CA10.7 cells (46 kDa). Brief (45 s) incubation of IMMC or PMC in glycine-HCl, pH 3, prior to iodination removed much of the surface-bound IgE. This permitted more thorough labeling of the receptors, but had no affect on the estimate of receptor size. Surprisingly and in contrast to acid-treated PMC, upon anti-IgE-Sepharose isolation acid-treated IMMC yielded an intensely radioactive Fc epsilon RI alpha band in the absence of added IgE. Such a finding suggests that IMMC, more so than PMC, may have an intracellular store of IgE, as has been suggested by many others. IMMC also differed from PMC in the number of forms of Fc epsilon RII isolated; 50-kDa and 58-kDa forms of Fc epsilon RII were obtained from IMMC, whereas PMC yielded most often a single 56-kDa Fc epsilon RII band. These results were mimicked by the two RBL cell sublines: RBL-2H3 cells yielded two Fc epsilon RII (46 kDa and 55 kDa), but only one form of Fc epsilon RII (54-kDa) was obtained from RBL-CA10.7 cells. Thus, the two subtypes of rat mast cells, which have previously been shown to differ in mediator profile and responsiveness to secretagogues and antiallergic drugs, are also distinguished by differences in IgER profile.

Animals↗
PubMed1989

Pulmonary inflammation in parasitic infection: immunoglobulins in bronchoalveolar washings of rats infected with Nippostrongylus brasiliensis.

Despite marked pulmonary pathology caused by larval stages of many helminth parasites, little is known about the mechanisms of immune and inflammatory responses to parasites in the respiratory tract. Using bronchoalveolar lavage (BAL) we have retrieved soluble proteins and cells from the respiratory tract of rats given a primary or secondary infection with the nematode Nippostrongylus brasiliensis. Total amounts of different immunoglobulin classes and albumin in BAL fluids and serum were quantitated using an ELISA. Analysis of the cellular component showed an increase in alveolar macrophages, neutrophils, eosinophils and lymphocytes on different days post-infection similar to our earlier findings. A time course study revealed that the concentrations of total protein, albumin, IgG, IgA and IgM in BAL fluids of infected animals were increased from days 2 to 32 after a primary infection. The magnitude of this increase was higher following a challenge infection (secondary) with the same parasite. Moreover, there was also a biphasic increase in total protein, IgG and IgA after secondary infections, with peaks on days 2 to 4 and 11 to 21 post-infection. A comparison of immunoglobulin to albumin ratios in serum and BAL fluids showed that the initial peak of proteins in the lavage was a result of serum leakage and the subsequent peak was due to local secretion of immunoglobulins. These results suggest that in addition to marked BAL cellular reactivity, N. brasiliensis infection induces an initial vascular and endothelial permeability in the respiratory tract which is soon repaired but followed by local synthesis and secretion of IgG and IgA in the lower respiratory tract.

Albumins↗
PubMed1989

IgE receptors from rat intestinal mucosal and peritoneal mast cells show mast cell subtype-specific differences.

High- (alpha chain) and low-affinity IgE receptors from purified populations of rat intestinal mucosal (IMMC) and peritoneal mast cells (PMC) were characterized by SDS-PAGE. Receptor expression and molecular weight were compared. IMMC yielded 59-kilodalton (kDa) alpha chains of the high-affinity receptors and two forms (58, 50 kDa) of low-affinity receptors, whereas PMC possessed only 51-kDa alpha chains and 56-kDa low-affinity receptors. These differences extend the evidence for functional diversity between mast cell subtypes.

Animals↗
PubMed1989

Interferon-alpha/beta inhibits IgE-dependent histamine release from rat mast cells.

Although mast cells and interferons are both involved in numerous immune and inflammatory responses, little is known about how microenvironmental factors such as interferons (IFNs) influence mast cell function. To study this question, sensitized peritoneal mast cells (greater than 98% purity) obtained from rats infected 4 weeks earlier with the parasite Nippostrongylus brasiliensis were preincubated for 24 hr with rat IFN-alpha/beta in RPMI-1640, then stimulated to degranulate with worm antigens. In the absence of antigen, IFN-alpha/beta had no noticeable effect on histamine release. However, in the presence of antigen, IFN-alpha/beta (150-1500 U/ml) inhibited histamine release in a dose-dependent manner (22.2 +/- 7.5% to 56.3 +/- 6.9%, n = 10). This inhibitory effect was neither heat (56 degrees for 1 hr) nor acid (pH 2 for 18 hr) labile, but was completely blocked by anti-IFN antibodies. In the presence of compound 48/80 (1 microgram/ml) or substance P (5 X 10(-5) M), IFN-alpha/beta was ineffective at modulating histamine release. Histamine release induced by antigen in the presence of the membrane phospholipid phosphatidyl-serine (30 micrograms/ml) was inhibited by IFN in a dose-dependent manner, but maximal inhibition (25.3 +/- 2.7%, n = 10) was reached at a lower concentration of IFN (750 U/ml) than when antigen was used alone. Therefore, rat IFN-alpha/beta appears to inhibit histamine release from rat mast cells in a dose- and stimulus-dependent manner and may do so by reducing the fluidity of the cell membrane.

Animals↗
PubMed1989

Effects of rat and human intestinal lamina propria cells on viability and muscle establishment of Trichinella spiralis newborn larvae.

Although eosinophils and other inflammatory cells from the circulation and peritoneal cavity can damage Trichinella spiralis newborn larvae (NBL) in vitro, the cytotoxic potential of cells from the intestinal lamina propria, a site that may be the first line of defense against NBL migration, is unknown. Accordingly, we examined the interaction between NBL and isolated intestinal lamina propria cells (ILPC), including an enriched eosinophil population, from rats and humans. Rat ILPC killed NBL in vitro only after a prolonged incubation of 6 days. However they strongly adhered to NBL after only 4 hr incubation and prevented muscle establishment of NBL injected intravenously. Human ILPC showed similar adherence as rat ILPC but no killing was seen at the incubation time tested (36 hr).

Animals↗
PubMed1988

Mast cell polymorphisms. Present concepts, future directions.

Although mast cells are widely distributed in the body, their functions are poorly known. The elucidation of mast cell function is complicated by growing evidence that mast cells are heterogeneous. Recent studies of mast cell ontogeny suggest that microenvironmental stimuli control the phenotypic expression of parts of the genome leading to subtype differences in a common lineage. Mast cells influence cell proliferation, differentiation, and activation in a range of target cells, although until recently they were considered important only in immediate hypersensitivity. However, they function in delayed-type hypersensitivity, potentiate cytotoxicity of eosinophils and macrophages, and are cytotoxic for certain targets themselves. Mast cell mediators influence blood flow and vascular permeability and facilitate angiogenesis. Numerous mast cell mediators are immunoregulatory. In vitro experiments have begun to investigate the role of mast cells in fibrotic diseases. Further knowledge of mast cell heterogeneity will provide the basis for new therapies in inflammatory diseases of the intestine and other organs.

Colitis, Ulcerative↗