Biomedical subjects

G Hetland

Publications and source records attributed to G Hetland.

At least 37 records · Page 2Linked to original sources

PubMed1998

Protective effect of beta-glucan against mycobacterium bovis, BCG infection in BALB/c mice.

Beta-1,3-glucan is a potent stimulator of macrophage functions and has a protective effect against a range of infections in rodent models. We examined whether the agent could also protect against the intracellular Mycobacterium bovis, bacillus Calmette-Guérin (BCG) infection in mice. BCG-susceptible BALB/c mice were injected intravenously (i.v.) with beta-glucan or vehicle 3 days before, or with beta-glucan 7 days after i.v. challenge with live BCG bacilli. The animals were killed 4 or 8 weeks later, their organs were homogenized and applied to object slides and stained with auramin for counting of bacilli, or seeded onto agar in Petri dishes. Mice treated with beta-glucan both pre- and postchallenge had significantly lower numbers of BCG bacilli and BCG colony-forming units in spleen homogenates compared with controls 4 weeks after challenge. A similar, but not statistically significant, tendency was observed in spleen homogenates from mice killed 8 weeks after challenge. In homogenates of liver and lungs there were similar findings, but less pronounced. There was a dose-dependent effect of beta-glucan injected before BCG challenge on the number of BCG bacilli found in spleen and liver homogenates. In addition, antibody cross-reactivity was demonstrated between M. tuberculosis cell wall and beta-glucan. The results suggest that beta-glucan has a protective effect against M. bovis, BCG infection in susceptible mice.

Animals↗

PubMed1998

Effect of filtration and storage of platelet concentrates on the production of the chemotaxins C5a, interleukin 8, tumor necrosis factor alpha, and leukotriene B4.

BACKGROUND: The production in platelet concentrates (PCs) of C3 activation products (C3bc), terminal complement complex (TCC), and chemotaxins C5a, interleukin (IL)-8, tumor necrosis factor alpha (TNFalpha), and leukotriene B4 (LTB4) and the proposed reduction in concentration of the chemotaxins by white cell reduction were examined. STUDY DESIGN AND METHODS: Samples were collected from supernatants of PCs produced by apheresis (apheresis PCs) or from buffy coats (BC PCs) immediately after the production, after white cell-reduction filtration on Day 1, and after 5-day storage, and examined by enzyme immunoassays. RESULTS: Complement was activated in all PCs during storage, and the concentration of activation products was not influenced by prestorage filtration. In prestorage white cell-reduced BC PCs, only C3bc levels increased. Levels of IL-8, TNFalpha, and LTB4 increased during storage of apheresis PCs, but not in filtered units, except for LTB4. In contrast, levels of IL-8 decreased after storage of filtered BC PCs. C5a correlated significantly with IL-8, which also correlated with TNFalpha and LTB4. CONCLUSION: Both C5a and TNFalpha generation in apheresis PCs seem to induce white cell IL-8 production, which mediates cellular LTB4 release. Prestorage white cell reduction is recommended for reducing chemotactic cytokine and leukotriene levels in all PCs. Production of BC PCs is recommended to achieve less complement activation, which is not affected by filtration.

Blood Platelets↗

PubMed1998

Involvement of antilipoarabinomannan antibodies in classical complement activation in tuberculosis.

We examined alternative and classical complement activation induced by whole bacilli of Mycobacterium bovis BCG and Mycobacterium tuberculosis products. After exposure to BCG, there were higher levels of the terminal complement complex in sera from Indian tuberculosis patients than in sera from healthy controls. The addition of BCG with or without EGTA to these sera indicated that approximately 70 to 85% of the total levels of the terminal complement complex was formed by classical activation. Sera from Indian tuberculosis patients contained more antibody to lipoarabinomannan (LAM) than sera from healthy Indians. Levels of anti-LAM immunoglobulin G2 (IgG2), but not anti-LAM IgM, correlated positively with classical activation induced by BCG in the sera. By flow cytometry, deposition of C3 and terminal complement complex on bacilli incubated with normal human serum was demonstrated. The anticomplement staining was significantly reduced in the presence of EGTA and EDTA. Flow cytometry also revealed the binding of complement to BCG incubated with rabbit anti-LAM and then with factor B-depleted serum. This indicates that classical activation plays a major role in complement activation induced by mycobacteria and that anti-LAM IgG on the bacilli can mediate this response. Classical complement activation may be important for the extent of phagocytosis of M. tuberculosis by mononuclear phagocytes, which may influence the course after infection.

Adolescent↗

PubMed1998

Chemotaxins C5a and fMLP induce release of calprotectin (leucocyte L1 protein) from polymorphonuclear cells in vitro.

AIMS: To determine whether the chemotaxins C5a and formyl peptide (fMLP) can stimulate the release of calprotectin, the major leucocyte protein of polymorphonuclear neutrophils (PMN). METHODS: A dose response curve for the uptake of 125I labelled rC5a and fMLP in PMN was determined by radioimmunoassay. The unlabelled chemotaxins were then incubated with PMN and the concentration of calprotectin in PMN lysates and supernatants was measured by an enzyme immunoassay. RESULTS: Both rC5a and fMLP induced release of calprotectin from PMN in a dose dependent manner as determined by a reduction in intracellular calprotectin concentration. A minimum of approximately 10% of total PMN calprotectin was retained at concentrations of 10-100 nM of rC5a and 0.1-10.0 nM of fMLP. Antibodies to C5a reduced the rC5a mediated release of calprotectin, and the fMLP antagonist N-t-Boc-MLP inhibited the fMLP induced calprotectin release. Because receptors for rC5a (CD88) and fMLP are G protein coupled and thought to be pertussis toxin sensitive, PMN were incubated with this toxin before the experiments. The toxin was found to reduce uptake of rC5a by the cells and to inhibit rC5a and fMLP mediated calprotectin release. CONCLUSIONS: rC5a and fMLP mediate release of calprotectin from PMN in vitro. This effect might be important during human infections in vivo.

Antigens, Surface↗

PubMed1998

Leucocyte filtration during cardiopulmonary bypass hardly changed leucocyte counts and did not influence myeloperoxidase, complement, cytokines or platelets.

In some patients, coronary artery bypass surgery induces postoperative organ dysfunction despite an apparently adequate revascularization and good haemodynamic performance. This complication may be caused by activation of the body's inflammatory systems on blood contact with large foreign surfaces in the extracorporeal circuit. Activated leucocytes may play an important role in organ damage, and it is conceivable that leucocyte removal by filtration may decrease the potential side-effects of cardiopulmonary bypass (CPB). The aim of the present study was to investigate possible effects of leucocyte filtration during the whole CPB period in elective coronary artery bypass surgery on biochemical and clinical parameters. Forty patients were randomized to extracorporeal circulation using a leucocyte-depleting filter (group L, n = 20) or to extracorporeal circulation with no leucocyte filter (group C, n = 20). In the leucocyte-depleted group, the mean total white blood cell counts increased from 6.3 (95% confidence interval, 5.5-7.0) x 10(9)/l to 7.0 (5.7-8.3) x 10(9)/l during extracorporeal circulation and in the control group from 6.3 (5.2-7.3) x 10(9)/l to 8.5 (7.2-9.8) x 10(9)/l. The intergroup difference was not statistically significant (p = 0.84). A substantial increase in concentrations of interleukin-6, myeloperoxidase and complement activation products were observed in both groups without statistically significant intergroup differences. It is concluded that the leucocyte-depletion filter did not cause a significant reduction of circulating white blood cells during CPB, and there were no significant differences between the groups with respect to the inflammatory markers studied.

Aged↗

PubMed1997

Both plasma- and leukocyte-associated C5a are essential for assessment of C5a generation in vivo.

BACKGROUND: Measurement of C5a in plasma is hampered by the rapid clearance of C5a as a result of cell binding. Therefore, an assessment of whether cell-bound C5a might better reflect C5a generation in vivo is essential. METHODS: We quantified plasma and leukocyte-bound C5a in samples from patients undergoing cardiopulmonary bypass, which is known to be associated with complement activation. C3 activation products and the terminal complement complex were measured as well. RESULTS: Plasma levels of C3 activation products and the terminal complement complex increased rapidly and significantly after the onset of cardiopulmonary bypass until they reached a plateau after 30 minutes. The concentration of plasma C5a increased steadily to twice baseline at the end of bypass. The concentration of leukocyte-associated C5a increased threefold after 10 minutes of cardiopulmonary bypass, when a plateau was reached. A positive correlation was found between levels of plasma C3 activation products or terminal complement complex and plasma C5a plus cell-associated C5a but not between C3 activation products or terminal complement complex and either one of the C5a variables. CONCLUSIONS: We conclude that both plasma C5a and leukocyte-associated C5a are needed for monitoring in vivo C5a generation.

Cardiopulmonary Bypass↗

PubMed1997

Cytotoxic effect of dibutyryl cAMP, phorbol-12-myristate-13-acetate and lipopolysaccharide, but not interferon-gamma, on promonocytic cell lines in vitro.

We studied whether inducers of cell differentiation alone could have cytotoxic effect on the promonocytic U937 and Mono Mac 6 cells in vitro. The cells were incubated with standard differentiating doses of interferon (IFN)-gamma, dibutyryl cAMP (Bt2cAMP) or the phorbol ester phorbol-12-myristate-13-acetate (PMA), with or without lipopolysaccharide (LPS), and both protein synthesis and viability were examined. In both U937 and Mono Mac 6 cells the incorporation of [3H]leucine was significantly reduced after PMA plus LPS stimulation, but not after IFN-gamma stimulation, when compared with controls. For U937 cells there was also reduced incorporation after Bt2cAMP stimulation. Trypan blue exclusion experiments and the number of cells remaining in the cultures indicated that Bt2cAMP-, PMA- and/or LPS-stimulated, but not IFN-gamma-stimulated, cells were less viable than unstimulated U937 or Mono Mac 6 cells. The results suggest that Bt2cAMP, PMA and LPS, but not IFN-gamma, are cytotoxic towards promonocytic cancer cell lines in vitro.

Bucladesine↗

PubMed1996

Cytotoxic effect of radiolabeled C5a on U937 cells in vitro.

We studied whether the receptor (R) for C5a could be exploited to deliver the radiolabeled ligand into U937 cells. A dose-response for uptake of 125I-C5a was demonstrated. Incorporation of [3H]leucine by unstimulated or gamma-INF-stimulated U937 cells treated with 125I-C5a, was significantly lower compared with cells treated with 125I alone. Trypan blue exclusion experiments indicated that gamma-INF stimulated cells incubated with 125I-C5a were less viable than cells exposed to 125I or C5a alone. The results suggest that 125I-C5a is internalized into myeloid cells via C5a-R and is more cytotoxic in vitro than the radiolabel alone, but only at/above a specific activity of 4 microCi/microg.

Cell Survival↗

PubMed1994

Antigen 85C on Mycobacterium bovis, BCG and M. tuberculosis promotes monocyte-CR3-mediated uptake of microbeads coated with mycobacterial products.

The uptake in monocytes of monodispersed latex microbeads precoated with whole bacillus Calmette-Guérin (BCG) cells, Mycobacterium tuberculosis sonicate or culture fluid, or antigen (Ag) from the culture fluid was examined by microscopy. There was a significantly higher cell association of beads coated with whole BCG cells, the secreted 85C component of the Ag 85 complex or M. tuberculosis sonicate than of phosphate-buffered saline (PBS)-treated control beads. Antibodies (Ab) to Ag 85 inhibited the uptake of BCG- and Ag 85C-treated beads. A monoclonal antibody (mAb) to complement receptor type 3 (CR3), but not mAb to CR1, inhibited the uptake of Ag 85C-coated beads, indicating that the mycobacterial Ag-dependent uptake of particles was mediated via CR3 on the monocytes. This points to the existence of a ligand on Ag 85C which may promote monocyte uptake of M. bovis, BCG and M. tuberculosis.

Antibodies, Monoclonal↗

PubMed1993

The B chain, but not the A chain, of Ricinus communis activates human complement.

Complement activation properties of ricin holotoxin, its A or B chain were assessed in two enzyme immunoassays (EIA). One was specific for C3 activation products and the other detected the terminal SC5b-9 complement complex (TCC) and thus determined activation of the initial and terminal part of the complement pathways, respectively. Ricin and its A and B chains were incubated with normal human serum or EDTA-serum. It was found that ricin B chain activated both the initial and terminal complement pathways in a time- and concentration-dependent fashion, whereas the A chain and the holotoxin did not.

Complement Activation↗

PubMed1992

Human umbilical vein endothelial cells synthesize S-protein (vitronectin) in vitro.

S-protein, also named vitronectin, is a multifunctional glycoprotein with molecular weight (MW) of about 75 kDa and a serum concentration of 0.14-0.60 mg/ml. It is synthesized mainly in the liver, but synthesis has also been found in monocytes/macrophages. We used human umbilical vein endothelial cells (EC) which were incubated with agarose beads, an activator of the alternative complement pathway. By radioimmunoassay (RIA) based on monoclonal and polyclonal S-protein antibodies, we detected S-protein on harvested agarose beads. The time-dependent increase in the amount of S-protein was significantly reduced by the presence of cycloheximide (10 micrograms/ml) in the cell cultures. We also found a strong binding of S-protein antibodies to agarose beads preincubated in native serum, which was strongly reduced (70-80%) by inactivation of the alternative complement pathway (50 degrees C, 20 min). Our results show that EC synthesize S-protein in vitro.

Cells, Cultured↗

PubMed1992

Co-variation of alanine aminotransferase levels with relative weight in blood donors.

The association between alanine aminotransferase (ALAT) and body mass, sex and age was examined in 6036 consecutively tested blood donors. ALAT, age and body mass were higher in male donors than in female donros. The non-normal ALAT distribution curve normalized after 1n transformation, which made statistical analysis of the data more feasible. Multiple regression analysis demonstrated that ALAT was influenced by sex and relative weight, in that order, and very poorly by age. It is concluded that obesity is a major cause of raised ALAT in this predominantly healthy donor population.

Adult↗

PubMed1992

Levels of calprotectin (leukocyte L1 protein) during apheresis.

The plasma concentration of calprotectin was measured before, during and after apheresis in patients with Guillain-Barré Syndrome (GBS), Waldenstrøm's syndrome or hypercholesterolaemia and in healthy donors of platelets. Increased calprotectin levels were found after plasma exchange in the Waldenstrøm's syndrome patients, probably caused by release of the protein from activated leukocytes. The decreased calprotectin values observed in the other patients, may be due to plasma dilution. Unexpectedly, the GBS patients were found to have high initial calprotectin levels in plasma but not in cerebrospinal fluid. In donors, normal and unchanged calprotectin concentrations were found throughout.

Blood Component Removal↗

PubMed1991

The use of flow cytometry to detect the biosynthesis of complement components.

Agarose beads, an activator of complement, were incubated with MRC-5 or He 9 fibroblast cell lines under serum-free conditions. The beads were tested for binding of anti-complement antibodies by flow cytometry with a FACS 440 using FITC-labelled anti-Ig detection antibodies. Controls consisted of co-cultured beads incubated with irrelevant antibody or albumin, beads maintained in cell cultures containing cycloheximide, and beads which were not exposed to cells. The histograms demonstrated positive staining with anti-C3c, -C5, -C7 and -C9, but not with anti-C6 and -C8. Flow cytometry with multiple histogram analysis confirmed that the differences between the positive curves and the controls were statistically significant. The results show that cell-derived complement components (C3, C5, C7 and C9) were deposited on the beads and could be detected by flow cytometry.

Cell Line↗

PubMed1991

[Viral hepatitis and blood transfusion].

Our findings show that hepatitis B-virus was transmitted by blood from two hepatitis B-surface-antigen (HBsAg)-negative but hepatitis B-coreantibody (anti-HBc)-positive donors. Blood donors and recipients were also tested for antibodies against the recently identified hepatitis C-virus (HCV). We found that two anti-HCV-positive donors with no known history of clinical hepatitis were chronic, infective carriers of HCV. The prevalence of anti-HCV in our blood donor population was 0.47% and ALT and anti-HBc testing was of no help for tracing the anti-HCV positives. We recommend that, in addition to HBsAg screening at each donation, donors are tested for anti-HBc and anti-HCV once. Individuals with a history of parenteral virus hepatitis should not be accepted as blood donors.

Blood Donors↗

PubMed1991

Human umbilical vein endothelial cells synthesize functional C3, C5, C6, C8 and C9 in vitro.

Human endothelial cells (EC), cultured serum-free, synthesize de novo protein which increasingly bind to agarose beads (an alternative pathway activator), until a plateau phase is reached after 24-48 h. EC synthesize functional C3, C5, C6, C8 and C9, which were detected on co-cultured agarose beads, using relevant polyclonal anti-complement antibodies. Two monoclonal anti-C9 neoepitope antibodies (aE11, poly C9-MA) bound to the co-cultured beads, showing that the terminal complement complex (TCC) (C5b-9) was assembled on the beads. This also suggests that C7 is synthesized. There seems to be a positive correlation between the amount of agarose-bound labelled protein and agarose-bound complement. The results indicate that EC produce and secrete the components for the functional alternative and terminal pathways of complement.

Antibodies, Monoclonal↗

PubMed1991

Infective, chronic carriers of hepatitis C virus among blood donors with no history of clinical hepatitis.

We investigated the infectivity of three hepatitis C virus antibody (anti-HCV) positive blood donors with either hepatitis B core antibodies (anti-HBc) (Nos 1 and 2) or raised alanine aminotransferase (ALT) (No. 3). The 57 recipients of blood products from these donors during the period 1971-1990 were identified and the living 23 were tested for anti-HCV. Among these, 11 out of 14 (78%) recipients from Nos 1 and 2, and 1 out of 9 (11%) recipients from No. 3 were anti-HCV positive. The former donors had high titres of anti-C100-3 and high rating scores in the HCV recombinant immunoblot assay (RIBA). They were evidently infective, chronic carriers of HCV but had no clinical signs or medical history of hepatitis. The latter donor had low titres of anti-C100-3 and a low RIBA rating score. She had clinical signs of chronic hepatitis and persistently elevated ALT, but only one of her recipients was anti-HCV positive.

Blood Donors↗

PubMed1991

Activation of complement during apheresis.

C3 activation products and the terminal complement complex (TCC) were examined in plasma during plasmapheresis of patients with Guillain-Barré Syndrome (GBS) (n = 4), Waldenström's syndrome (n = 4), and hypercholesterolaemia (n = 1), or during cytapheresis of platelet (n = 10) and granulocyte (n = 2) donors. Blood specimens were taken before, during and after the procedures. There was a significant activation of complement after apheresis in the GBS patients and one of the patients with Waldenström's syndrome, but not in the other patients. There were no significant differences in complement activation products before compared with after cytapheresis in the healthy donors. This demonstrates the biocompatibility with respect to complement activation of the materials used. The observed complement activation in some of the patients during plasma exchange is probably caused by activation products in the replacement plasma.

Complement Activation↗