Biomedical subjects

A Verbon

Publications and source records attributed to A Verbon.

At least 19 recordsLinked to original sources

PubMed2006

[Non-antibiotic prophylaxis for recurrent urinary-tract infections].

Urinary-tract infections (UTIs) occur frequently and hence have significant financial implications. Antibiotic prophylaxis can be considered in women with recurrent UTIs. However, frequent exposure to antibiotics can lead to antimicrobial resistance and side effects. The most important steps in the pathogenesis of UTIs are the colonisation and adherence of uropathogens. Lactobacilli impede intravaginal colonisation by competing with uropathogens. Cranberries interfere with the adherence of uropathogens to uroepithelial cells. Therefore, cranberries and lactobacilli are potential alternatives in the prophylaxis of UTIs. Randomised clinical trials comparing these compounds with long-term, low-dose antibiotics for the prevention of recurrent UTIs in women have not yet been conducted. Such a trial has recently been started in The Netherlands: the 'Non-antibiotic versus antibiotic prophylaxis for recurrent urinary-tract infections' (NAPRUTI) study.

Female↗

PubMed2004

Abnormal radiological findings and a decreased carbon monoxide transfer factor can persist long after the acute phase of Legionella pneumophila pneumonia.

Pulmonary abnormalities may persist long after the acute phase of legionnaires disease (LD). In a cohort of 122 survivors of an outbreak of LD, 57% were still experiencing an increased number of symptoms associated with dyspnea at a mean of 16 months after recovery from acute-phase LD. For 86 of these patients, additional evaluation involving high-resolution computed tomography (HRCT) of the lung revealed pulmonary abnormalities in 21 (24%); abnormal HRCT findings generally presented as discrete and multiple radiodensities. Residual pulmonary abnormalities were associated with a mean reduction of 20% in the gas transport capacity of the lung. This latter sign could not be used to explain the increased symptoms of dyspnea reported by patients. Receipt of mechanical ventilation during the acute phase of LD, delayed initiation of adequate antibiotic therapy, and chronic obstructive pulmonary disease were identified as risk factors for the persistence of lung abnormalities.

Aged↗

PubMed2003

[Indications for, and the significance of, the tuberculin test in the Netherlands].

The almost 100-year-old tuberculin skin test still is the gold standard for diagnosing Mycobacterium tuberculosis infection. The sensitivity of this test with the usual cut-off values is high, but may be decreased with impaired cellular immunity and at older age. The specificity is primarily determined by cross-reactivity to atypical mycobacterial infections and vaccination with Bacillus Calmette-Guérin (BCG). Positivity of the skin test after BCG vaccination decreases with time after vaccination and depends on the age when vaccinated. The tuberculin reaction can be boosted by repeated tuberculin skin tests over a short time period, whereby the anamnestic immune response is stimulated. This boosting phenomenon occurs mostly with atypical mycobacterial infections, after BCG vaccination and at older age. Interpretation of the tuberculin skin test depends on the indication for the test, the expected risk of latent tuberculosis infection, higher prevalence of 'old' tuberculosis in elderly Dutch people and immigrants, BCG vaccination status and, if a baseline value is available, the boosting phenomenon. Its role in the diagnosis of tuberculosis is limited.

BCG Vaccine↗

PubMed2003

Reduced interferon-gamma release in patients recovered from Legionnaires' disease.

BACKGROUND: Legionella pneumophila, a Gram negative intracellular pathogen, causes Legionnaires' disease (LD). Interferon (IFN)-gamma is important for host defence against L pneumophila so reduced IFN-gamma production capacity and/or responsiveness might render humans more susceptible to infection with L pneumophila. METHODS: Seventy seven patients who suffered from LD after a point source outbreak one year earlier participated in the study. Whole blood was incubated with non-specific stimuli (lipopolysaccharide (LPS) or interleukin (IL)-12) or specific stimuli (viable or heat killed L pneumophila) to evaluate IFN-gamma production, and with IFN-gamma to evaluate IFN-gamma responsiveness. Expression of complement receptor 3 on monocytes was determined by flow cytometry. Thirty seven companions who were also exposed but had not developed LD served as controls. RESULTS: Patients released less IFN-gamma than controls in response to stimulation with LPS (mean (SE) 393 (58) pg/ml v 914 (178) pg/ml; p=0.001) and IL-12 (96 (14) pg/ml v 177 (41) pg/ml; p=0.058). IFN-gamma responsiveness, measured by release of IFN-gamma inducible protein (IP)-10, tumour necrosis factor alpha, IL-12 production capacity, and monocyte expression of complement receptor 3, did not differ between patients and controls. IFN-gamma release after stimulation with LPS and IP-10 release after stimulation with IFN-gamma were weakly associated with severity of LD in the former patient group (rho=-0.3, p=0.011 and rho=-0.3, p=0.037, respectively). CONCLUSION: These results suggest that impaired IFN-gamma production may contribute to susceptibility to L pneumophila infection.

Aged↗

PubMed2002

Mice lacking the multidrug resistance protein 1 have a transiently impaired immune response during tuberculosis.

A T helper (Th) 1 immune response is important for host defense against tuberculosis. The multidrug resistance protein (Mrp) 1 is constitutively present at low levels on Th2 lymphocytes, and is expressed on Th1 lymphocytes upon activation. To determine the role of Mrp1 in the pathogenesis of tuberculosis, Mrp1 deficient (-/-) and normal wild type mice were intranasally infected with Mycobacterium tuberculosis. At 2 weeks after infection, Mrp1(-/-) mice had reduced levels of the Th1 cytokine interferon-gamma and an impaired granuloma formation in their lungs. At 5 weeks postinfection, M. tuberculosis outgrowth was enhanced in lungs and livers of Mrp1(-/-) mice. A more prolonged observation of these mice, up to 4 months, revealed no differences in survival or mycobacterial outgrowth. These data suggest that Mrp1 plays an early but dispensable role in the protective immune response to pulmonary tuberculosis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Depletion of alveolar macrophages exerts protective effects in pulmonary tuberculosis in mice.

Mycobacterium tuberculosis bacilli are intracellular organisms that reside in phagosomes of alveolar macrophages (AMs). To determine the in vivo role of AM depletion in host defense against M. tuberculosis infection, mice with pulmonary tuberculosis induced by intranasal administration of virulent M. tuberculosis were treated intranasally with either liposome-encapsulated dichloromethylene diphosphonate (AM(-) mice), liposomes, or saline (AM(+) mice). AM(-) mice were completely protected against lethality, which was associated with a reduced outgrowth of mycobacteria in lungs and liver, and a polarized production of type 1 cytokines in lung tissue, and by splenocytes stimulated ex vivo. AM(-) mice displayed deficient granuloma formation, but were more capable of attraction and activation of T cells into the lung and had increased numbers of pulmonary polymorphonuclear cells. These data demonstrate that depletion of AMs is protective during pulmonary tuberculosis.

Administration, Intranasal↗

PubMed2001

IC14, an anti-CD14 antibody, inhibits endotoxin-mediated symptoms and inflammatory responses in humans.

CD14 is a receptor for cell wall components of Gram-negative and Gram-positive bacteria that has been implicated in the initiation of the inflammatory response to sepsis. To determine the role of CD14 in LPS-induced effects in humans, 16 healthy subjects received an i.v. injection of LPS (4 ng/kg) preceded (-2 h) by i.v. IC14, a recombinant chimeric mAb against human CD14, at a dose of 1 mg/kg over 1 h, or placebo. In subjects receiving IC14, saturation of CD14 on circulating monocytes and granulocytes was >90% at the time of LPS injection. IC14 attenuated LPS-induced clinical symptoms and strongly inhibited LPS-induced proinflammatory cytokine release, while only delaying the release of the anti-inflammatory cytokines soluble TNF receptor type I and IL-1 receptor antagonist. IC14 also inhibited leukocyte activation, but more modestly reduced endothelial cell activation and the acute phase protein response. The capacity of circulating monocytes and granulocytes to phagocytose Escherichia coli was only marginally reduced after infusion of IC14. These data provide the first proof of principle that blockade of CD14 is associated with reduced LPS responsiveness in humans in vivo.

Acute-Phase Proteins↗

PubMed2001

Patients with active tuberculosis have increased expression of HIV coreceptors CXCR4 and CCR5 on CD4(+) T cells.

Expression of human immunodeficiency virus (HIV) coreceptors CXCR4 and CCR5 was found to be elevated on CD4(+) T cells (1) in blood samples obtained from patients with tuberculosis and (2) in blood samples obtained from healthy subjects and stimulated with mycobacterial lipoarabinomannan in vitro. These data suggest that the increase in HIV viremia that occurs in association with tuberculosis may result from up-regulation of CXCR4 and CCR5 on CD4(+) T cells, thereby causing acceleration of HIV infection.

Adult↗

PubMed2001

Thalidomide inhibits granulocyte responses in healthy humans after ex vivo stimulation with bacterial antigens.

Ingestion of thalidomide was associated with a reduction in the upregulation of the granulocyte activation marker CD11b and a reduced capacity to release elastase and lactoferrin after stimulation with lipopolysaccharide or lipoteichoic acid. A single oral dose of thalidomide attenuates neutrophil activation upon ex vivo stimulation with bacterial antigens.

Anti-Inflammatory Agents↗

PubMed2001

Concurrent upregulation of urokinase plasminogen activator receptor and CD11b during tuberculosis and experimental endotoxemia.

Patients with tuberculosis had higher expression of monocyte urokinase receptor (uPAR) and CD11b than controls. In vitro, lipoarabinomannan and lipopolysaccharide (LPS) from Escherichia coli shared the ability to enhance uPAR and CD11b expression on monocytes and granulocytes. In healthy volunteers, LPS induced increases in monocyte and granulocyte uPAR and CD11b.

Adult↗

PubMed2000

Up-regulation of HIV coreceptors CXCR4 and CCR5 on CD4(+) T cells during human endotoxemia and after stimulation with (myco)bacterial antigens: the role of cytokines.

Concurrent infections in patients with human immunodeficiency virus (HIV) infection stimulate HIV replication. Chemokine receptors CXCR4 and CCR5 can act as HIV coreceptors. The authors hypothesized that concurrent infection increases the HIV load through up-regulation of CXCR4 and CCR5. Using experimental endotoxemia as a model of infection, changes in HIV coreceptor expression were assessed in 8 subjects injected with lipopolysaccharide (LPS, 4 ng/kg). The expression of CXCR4 and CCR5 on CD4(+) T cells was increased 2- to 4-fold, 4 to 6 hours after LPS injection. In whole blood in vitro, LPS induced a time- and dose-dependent increase in the expression of CXCR4 and CCR5 on CD4(+) T cells. Similar changes were observed after stimulation with cell wall components of Mycobacterium tuberculosis (lipoarabinnomannan) or Staphylococcus aureus (lipoteichoic acid), or with staphylococcal enterotoxin B. LPS increased viral infectivity of CD4-enriched peripheral blood mononuclear cells (PBMCs) with a T-tropic HIV strain. In contrast, M-tropic virus infectivity was reduced, possibly because of elevated levels of the CCR5 ligand cytokines RANTES and MIP-1beta. LPS-stimulated up-regulation of CXCR4 and CCR5 in vitro was inhibited by anti-TNF and anti-IFN gamma. Incubation with recombinant TNF or IFN gamma mimicked the LPS effect. Anti-interleukin 10 (anti-IL-10) reduced CCR5 expression, without influencing CXCR4. In accordance, rIL-10 induced up-regulation of CCR5, but not of CXCR4. Intercurrent infections during HIV infection may up-regulate CXCR4 and CCR5 on CD4(+) T cells, at least in part via the action of cytokines. Such infections may favor selectivity of HIV for CD4(+) T cells expressing CXCR4. (Blood. 2000;96:2649-2654)

Adult↗

PubMed2000

Reduced ex vivo chemokine production by polymorphonuclear cells after in vivo exposure of normal humans to endotoxin.

Monocytes from patients with sepsis have a reduced capacity to produce cytokines, a state referred to as immunoparalysis. To determine whether polymorphonuclear leukocytes (PMNL) can be rendered hyporesponsive, PMNL from 6 healthy volunteers intravenously challenged with lipopolysaccharide (LPS; 4 ng/kg) were stimulated ex vivo with heat-killed bacteria or LPS, and the release of the CXC chemokines interleukin-8, epithelial-derived neutrophil attractant-78, and growth-related oncogen-alpha was measured. At 1 and 2 h after LPS administration in vivo, PMNL produced fewer CXC chemokines after stimulation with bacteria or LPS (all P<.05). Serum obtained 2 h after in vivo administration of LPS did not influence chemokine production by PMNL from 6 healthy volunteers not previously exposed to LPS. Thus, intravenous injection of LPS induces a refractory state of PMNL that is not caused by soluble factors produced in response to in vivo exposure to LPS.

Adult↗

PubMed2000

Interleukin-1 signaling is essential for host defense during murine pulmonary tuberculosis.

Interleukin (IL)-1 signaling is required for the containment of infections with intracellular microorganisms, such as Listeria monocytogenes and Leishmania major. To determine the role of IL-1 in the host response to tuberculosis, we infected IL-1 type I receptor-deficient (IL-1R(-/-)) mice, in which IL-1 does not exert effects, with Mycobacterium tuberculosis. IL-1R(-/-) mice were more susceptible to pulmonary tuberculosis, as reflected by an increased mortality and an enhanced mycobacterial outgrowth in lungs and distant organs, which was associated with defective granuloma formation, containing fewer macrophages and fewer lymphocytes, whereas granulocytes were abundant. Lymphocytes were predominantly confined to perivascular areas, suggesting a defective migration of cells into inflamed tissue in the absence of IL-1 signaling. Impaired host defense in IL-1R(-/-) mice was further characterized by a decrease in the ability of splenocytes to produce interferon-gamma. Analysis of these data suggests that IL-1 plays an important role in the immune response to M. tuberculosis.

Animals↗

PubMed2000

Thalidomide suppresses Up-regulation of human immunodeficiency virus coreceptors CXCR4 and CCR5 on CD4+ T cells in humans.

Concurrent infection in patients with human immunodeficiency virus (HIV) infection increases the expression of HIV coreceptors CXCR4 and CCR5. Thalidomide has beneficial effects in a number of HIV-associated diseases. The effect of thalidomide on CXCR4 and CCR5 expression on CD4+ T cells was determined. Thalidomide produced a dose-dependent inhibition of lipopolysaccharide (LPS)-induced up-regulation of CXCR4 and CCR5 in vitro. Antibody to tumor necrosis factor-alpha (TNF-alpha) also attenuated the LPS-induced HIV coreceptor up-regulation, which was not further reduced by thalidomide. Thalidomide (400 mg) was orally administered to 6 men, and their blood was stimulated ex vivo with LPS, staphylococcal or mycobacterial antigens, or antibody to CD3 or CD28 cells. All stimuli induced up-regulation of HIV coreceptors, which was reduced after ingestion of thalidomide. Thalidomide may be beneficial in the treatment of intercurrent infections during HIV infection by reducing the up-regulation of CXCR4 and CCR5 expression on CD4+ T cells induced by bacterial and mycobacterial antigens, by a mechanism that involves inhibition of TNF-alpha.

Adult↗

PubMed2000

A single oral dose of thalidomide enhances the capacity of lymphocytes to secrete gamma interferon in healthy humans.

Thalidomide is increasingly being used as adjuvant therapy for patients with mycobacterial and human immunodeficiency virus (HIV) infections. The T-helper (Th)1 cytokine-Th2 cytokine balance critically determines the outcomes of these diseases. To obtain insight into the effect of thalidomide on the capacity of lymphocytes to produce Th1 and Th2 cytokines, six healthy volunteers received an oral dose (400 mg) of thalidomide. Before and at 3, 6, and 24 h after ingestion of thalidomide, peripheral blood mononuclear cells (PBMCs) were isolated and stimulated for 24 h with the T-cell stimulant staphylococcal enterotoxin B (SEB) or anti-CD3/CD28. In all six volunteers ingestion of thalidomide was associated with enhanced SEB- and anti-CD3/CD28-induced production of the Th1 cytokine gamma interferon (P < 0.05) and a decrease in the level of anti-CD3/CD28-induced interleukin-5 (IL-5) production (P < 0.05). The levels of IL-2 (Th1) and IL-4 (Th2) released remained unchanged. These changes were accompanied by an increase in the amount of IL-12p40 released by the PBMCs 6 h after ingestion of thalidomide (P < 0.05). Thus, a single oral dose of thalidomide causes a Th1-type response in healthy humans. This finding offers a potential explanation for the positive effect of thalidomide in patients with mycobacterial and HIV infections.

Adult↗

PubMed2000

Mycobacterial lipoarabinomannan induces an inflammatory response in the mouse lung. A role for interleukin-1.

Lipoarabinomannan (LAM), a cell wall component of Mycobacterium tuberculosis, induces the production of cytokines and chemokines in vitro. Interleukin-1 (IL-1) contributes to granuloma formation in tuberculosis (TB), and exerts effects via the IL-1 receptor type I (IL-1R). To determine the effects of LAM in the pulmonary compartment in vivo and to establish the role of endogenous IL-1 herein, normal and IL-1R deficient ((-/-)) mice were intranasally inoculated with LAM (50 microgram). In normal mice, LAM resulted in a neutrophilic cell influx into the bronchoalveolar lavage fluid (BALF). LAM also induced increases in the lung concentrations of macrophage inflammatory protein-2 (MIP-2), keratinocyte (KC), tumor necrosis factor-alpha (TNF-alpha), IL-1alpha, and IL-1beta. IL-1R(-/-) mice had less influx of granulocytes in their BALF than wild-type mice. Also, lung TNF-alpha levels were lower in IL-1R(-/-) mice. LAM may be an important stimulator of innate immunity in infection with M. tuberculosis via mechanisms that involve endogenous IL-1 activity.

Animals↗

PubMed1999

Quantitative determination of thalidomide in human serum with high-performance liquid chromatography using protein precipitation with trichloroacetic acid and ultraviolet detection.

A validated and precise reversed-phase high-performance liquid chromatographic method for the determination of thalidomide in serum, with phenacetin as an internal standard, is described. Protein precipitation, using trichloroacetic acid, was used for clean-up. The aliquot was chromatographed on a octadecyl column, using an eluent composed of 250 ml 0.01 M potassium dihydrogenphosphate, adjusted to a pH of 3.0 with a 43% phosphoric acid solution, mixed with 750 ml methanol. Ultraviolet detection was used at an operation wavelength of 220 nm. Hydrolytic degradation was prevented during analysis by acidification of samples with the precipitation reagent. Thalidomide and phenacetin were found to have retention times of 7.9 and 15.0 min, respectively. Recoveries ranging from 79 to 84% were found for both components, with reproducibility relative standard deviations of 0.8-3% and repeatability coefficients of 1.2-3%. A mean correlation coefficient of 0.9995 was found for the linear calibration curve (n=2) of thalidomide with limits of quantitation of 0.222-21 mg/l. The method appeared to be feasible for pharmacokinetic studies with thalidomide.

Blood Proteins↗

PubMed1999

Serum concentrations of cytokines in patients with active tuberculosis (TB) and after treatment.

During TB cytokines play a role in host defence. To determine the cytokine pattern during various disease stages of TB, serum levels of IL-12, interferon-gamma (IFN-gamma), IL-4, IL-6 and IL-10 were measured in 81 patients with active TB, 15 patients during therapy and 26 patients after anti-tuberculous therapy as well as in 16 persons who had been in close contact with smear-positive TB and in 17 healthy controls. IFN-gamma was elevated during active TB when compared with healthy controls, declining during and after treatment. IL-12 (p40 and p70) serum levels were not significantly higher in patients with active TB compared with any of the other groups. IL-4 levels were low in all groups. IL-6 and IL-10 serum levels were elevated in patients with active TB and during treatment. In patients with active TB serum levels of IFN-gamma and IL-6 were higher in patients with fever, anorexia and malaise. IL-12 levels were higher in patients with a positive smear. Cytokine levels did not correlate with localization of TB (pulmonary versus extrapulmonary), or skin test positivity. Cytokines directing a Th1 response (IL-12) or a Th2 response (IL-4) were not elevated in sera of this large group of patients with pulmonary and extrapulmonary TB. In patients with active TB, cytokines that were elevated in serum were IFN-gamma, IL-6 and IL-10.

Adolescent↗