Biomedical subjects

S J van Deventer

Publications and source records attributed to S J van Deventer.

At least 19 recordsLinked to original sources

PubMed1999

Infliximab for the treatment of fistulas in patients with Crohn's disease.

BACKGROUND: Enterocutaneous fistulas are a serious complication of Crohn's disease and are difficult to treat. Infliximab, a chimeric monoclonal antibody to tumor necrosis factor alpha, has recently been developed as a treatment for Crohn's disease. We conducted a randomized, multicenter, double-blind, placebo-controlled trial of infliximab for the treatment of fistulas in patients with Crohn's disease. METHODS: The study included 94 adult patients who had draining abdominal or perianal fistulas of at least three months' duration as a complication of Crohn's disease. Patients were randomly assigned to receive one of three treatments: placebo (31 patients), 5 mg of infliximab per kilogram of body weight (31 patients), or 10 mg of infliximab per kilogram (32 patients); all three were to be administered intravenously at weeks 0, 2, and 6. The primary end point was a reduction of 50 percent or more from base line in the number of draining fistulas observed at two or more consecutive study visits. A secondary end point was the closure of all fistulas. RESULTS: Sixty-eight percent of the patients who received 5 mg of infliximab per kilogram and 56 percent of those who received 10 mg per kilogram achieved the primary end point, as compared with 26 percent of the patients in the placebo group (P=0.002 and P=0.02, respectively). In addition, 55 percent of the patients assigned to receive 5 mg of infliximab per kilogram and 38 percent of those assigned to 10 mg per kilogram had closure of all fistulas, as compared with 13 percent of the patients assigned to placebo (P=0.001 and P=0.04, respectively). The median length of time during which the fistulas remained closed was three months. More than 60 percent of patients in all the groups had adverse events. For patients treated with infliximab, the most common were headache, abscess, upper respiratory tract infection, and fatigue. CONCLUSIONS: Infliximab is an efficacious treatment for fistulas in patients with Crohn's disease.

Adult↗

PubMed1999

Cyclooxygenase-dependent signalling: molecular events and consequences.

Non-steroidal anti-inflammatory drugs (NSAIDs) currently attract large interest. Next to pain relief, NSAIDs have important anti-thrombotic and anti-oncogenic effects. NSAIDs exert their action by inhibition of cyclooxygenase, the enzyme responsible for the production of prostanoids. Prostanoid signal transduction is still poorly understood, but it has become clear that these inflammatory lipids influence cellular physiology at three different levels: (1) activation of a 7 x transmembrane receptor coupled to heterotrimeric G proteins, (2) the inhibition of inflammation by activating corticosteroid-like receptors, (3) participation in receptor protein tyrosine kinase signal transduction. In this review prostanoid signalling at these three different levels will be reviewed and the relevance in (patho)physiological processes will be evaluated.

Humans↗

PubMed1999

[Chlamydia pneumoniae as a causative agent in atherosclerosis].

There are indications that inflammatory mechanisms play a part in the development of atherosclerosis, and infections by various micro-organisms have been related to the development of atherosclerotic lesions of vascular walls. Epidemiological observations, immunohistochemical examination of samples of vascular wall and studies in laboratory animals have yielded strong indications that infections with Chlamydia pneumoniae, a Gram-negative bacterium, are related to the development of atherosclerosis and occurrence of myocardial infarction. Complications after a myocardial infarction are also connected with seropositivity for C. pneumoniae. These findings suggest a connection between (airway) infections caused by C. pneumoniae and the development of atherosclerosis. A possible pathogenic factor is that endotoxins are moved by lipoproteins and after incorporation of the lipoproteins into the vascular wall may cause a local inflammation.

Adolescent↗

PubMed1999

Multiple signal transduction pathways regulate TNF-induced actin reorganization in macrophages: inhibition of Cdc42-mediated filopodium formation by TNF.

TNF is known to regulate macrophage (Mphi) migration, but the signaling pathways mediating this response have not been established. Here we report that stimulation of the 55-kDa TNF receptor (TNFR-1) induced an overall decrease in filamentous actin (F-actin), inhibited CSF-1- and Cdc42-dependent filopodium formation, and stimulated macropinocytosis. Using a panel of TNFR-1 mutants, the regions of the receptor required for each of these responses were mapped. The decrease in F-actin required both the death domain and the membrane proximal part of the receptor, whereas inhibition of filopodium formation and increased pinocytosis were only dependent upon a functional death domain. When the TNF-induced decrease in F-actin was inhibited using either receptor mutants or the compound D609, TNF-stimulated actin reorganization at the cell cortex became apparent. This activity was dependent upon the FAN-binding region of TNFR-1. We conclude that different domains of TNFR-1 mediate distinct changes in the Mphi cytoskeleton, and that the ability of TNF to inhibit Mphi chemotaxis may be due to decreased filopodium formation downstream of Cdc42.

Actins↗

PubMed1999

Inflammatory bowel disease and the genes for the natural resistance-associated macrophage protein-1 and the interferon-gamma receptor 1.

The genes for the interferon-gamma receptor 1 and the natural resistance-associated macrophage protein 1 (NRAMP1) control the immune response to intracellular microbial pathogens. Such pathogens, in particular Mycobacterium paratuberculosis, have been implicated in the pathogenesis of Crohn's disease. We studied markers in the genes for NRAMP1 and two mutations in the interferon-gamma receptor in relation to inflammatory bowel disease (IBD) in the following groups: 270 healthy individuals, 74 patients with Crohn's disease, 72 patients with ulcerative colitis, and 40 patients with primary sclerosing cholangitis. We studied the allele frequencies of two restriction fragment length polymorphisms in the gene for NRAMP1 and the prevalence of two mutations in the interferon-gamma receptor 1 gene. The markers in the NRAMP1 gene were not associated with inflammatory bowel disease. Also, the mutations in the interferon-gamma receptor 1 were not found in the 186 IBD patients. Genetic markers in NRAMP1 are thus not associated with IBD. Therefore this gene is not likely to play a role in the pathogenesis of IBD. The mutation in the interferon-gamma receptor was not found in our IBD patients group.

Adult↗

PubMed1999

A genomewide analysis provides evidence for novel linkages in inflammatory bowel disease in a large European cohort.

Inflammatory bowel disease (IBD) is characterized by a chronic relapsing intestinal inflammation, typically starting in early adulthood. IBD is subdivided into two subtypes, on the basis of clinical and histologic features: Crohn disease and ulcerative colitis (UC). Previous genomewide searches identified regions harboring susceptibility loci on chromosomes 1, 3, 4, 7, 12, and 16. To expand our understanding of the genetic risk profile, we performed a 9-cM genomewide search for susceptibility loci in 268 families containing 353 affected sibling pairs. Previous linkages on chromosomes 12 and 16 were replicated, and the chromosome 4 linkage was extended in this sample. New suggestive evidence for autosomal linkages was observed on chromosomes 1, 6, 10, and 22, with LOD scores of 2.08, 2.07, 2.30, and 1.52, respectively. A maximum LOD score of 1.76 was observed on the X chromosome, for UC, which is consistent with the clinical association of IBD with Ullrich-Turner syndrome. The linkage finding on chromosome 6p is of interest, given the possible contribution of human leukocyte antigen and tumor necrosis-factor genes in IBD. This genomewide linkage scan, done with a large family cohort, has confirmed three previous IBD linkages and has provided evidence for five additional regions that may harbor IBD predisposition genes.

Cohort Studies↗

PubMed1999

Interleukin-12 induces sustained activation of multiple host inflammatory mediator systems in chimpanzees.

To determine in vivo effects of interleukin (IL)-12 on host inflammatory mediator systems, 4 healthy chimpanzees received recombinant human IL-12 (1 microg/kg) by intravenous injection. IL-12 induced increases in plasma concentrations of IL-15, IL-18, and interferon-gamma (IFN-gamma), plus a marked antiinflammatory cytokine response (IL-10, soluble tumor necrosis factor [TNF] receptors, IL-1 receptor antagonist) and secretion of alpha-chemokines (IL-8, IFN-gamma-inducible protein 10) and beta-chemokines (monocyte chemoattractant protein-1, macrophage inflammatory protein-1beta). In addition, IL-12 elicited neutrophilic leukocytosis, neutrophil degranulation (elastase-alpha1-antitrypsin complexes), coagulation activation (F1 + 2 prothrombin fragment, thrombin-antithrombin III complexes), and fibrinolytic activation (tissue-type plasminogen activator, plasmin-alpha2-antiplasmin complexes). IL-12-induced activation of multiple host mediator systems was found only after 8-24 h, remained detectable until the end of the 48-h observation period, and occurred in the absence of detectable TNF and IL-1beta. These data may contribute to understanding the role of IL-12 in the pathogenesis of sepsis syndrome and the toxicity found after repeated injections of IL-12.

Animals↗

PubMed1999

Thoracic duct in patients with multiple organ failure: no major route of bacterial translocation.

OBJECTIVE: To determine whether translocation of bacteria or endotoxin occurred into the thoracic duct in patients with multiple organ failure (MOF). SUMMARY BACKGROUND DATA: Translocation of bacteria or endotoxin has been proposed as a causative factor for MOF in patients without an infectious focus, although it has rarely been demonstrated in patients at risk for MOF. Most studies have investigated the hematogenic route of translocation, but it has been argued that lymphatic translocation of bacteria or endotoxin by the thoracic duct is the major route of translocation. METHODS: The thoracic duct was drained for 5 days in patients with MOF caused either by generalized fecal peritonitis (n = 4) or by an event without clinical and microbiologic evidence of infection (n = 4). Patients without MOF who were undergoing a transthoracic esophageal resection served as controls. In lymph and blood, concentrations of endotoxin, proinflammatory cytokines, and antiinflammatory cytokines were measured. RESULTS: Endotoxin concentrations in lymph and blood of patients with MOF ranged from 39 to 63 units per liter and were not significantly different from concentrations in patients without MOF. The quantity of endotoxin transported by the thoracic duct in the study group was small. In patients with MOF, low levels of proinflammatory cytokines and high levels of antagonists of these cytokines were found. CONCLUSION: This study provides evidence that translocation (especially of endotoxin) occurs into the thoracic duct. However, these data do not support the concept that the thoracic duct is a major route of bacterial translocation in patients with MOF.

Aged↗

PubMed1999

Does ursodeoxycholic acid mediate immunomodulatory and anti-inflammatory effects in patients with primary sclerosing cholangitis?

BACKGROUND AND OBJECTIVES: Therapy with ursodeoxycholic acid (UDCA) has been reported to be associated with improvements in abnormal serum biochemical liver tests in patients with primary sclerosing cholangitis (PSC). To evaluate further the effects of UDCA on this disease, we evaluated immunological markers and indices of inflammation during a one-year, prospective, open-label trial of UDCA therapy in patients with PSC. PATIENTS AND METHODS: Seventeen PSC patients were enrolled for one year of treatment with UDCA 12-15 mg/kg/day. Serum biochemical variables, immunological markers and indices of inflammation were compared before and at the end of therapy and 4 months after treatment had been withdrawn. Liver histology and immunohistochemistry for human leucocyte antigen (HLA) class I/II and intercellular adhesion molecule 1 (ICAM-1) expression were compared before and at the end of therapy. RESULTS: UDCA treatment was associated with significant improvements in serum biochemical liver tests, immunoglobulin levels and blood coagulation factors. Tumour necrosis factor alpha (TNF-alpha) production after in vitro whole-blood phytohaemagglutinin (PHA) stimulation was increased, but unaltered by UDCA therapy. Baseline serum levels of interleukin-6 (IL-6) and soluble IL-2 receptor were normal, and serum IL-8 levels were increased, but none of these variables was significantly affected by UDCA therapy. Liver histological stage/grade and HLA class I/II and ICAM-1 expression on biliary epithelial cells and hepatocytes were not markedly altered by UDCA therapy. CONCLUSIONS: UDCA therapy in PSC patients was associated with a decrease in cholestasis, but no consistent improvement in hepatic inflammation, fibrosis or histological stage of the disease. Immunomodulatory effects of UDCA in PSC do not appear to be HLA-restricted.

Adjuvants, Immunologic↗

PubMed1998

Activation of clotting factor XI without detectable contact activation in experimental human endotoxemia.

Evidence of factor XI (FXI) activation in vivo is scarce. In addition, it remains uncertain whether thrombin, factor XIIa (FXIIa), or perhaps another protease is responsible for FXI conversion. We investigated the activation of FXI in eight healthy volunteers after infusion of a low dose of endotoxin (4 ng/kg of body weight). Activation of prekallikrein FXII, FXI, and prothrombin was measured with sensitive enzyme-linked immunosorbent assays (ELISAs), and FXI activation was measured with a novel enzyme capture assay that detects noncomplexed FXIa. Activation of FXI was apparent with a significant plasma peak level of noncomplexed FXIa of 10 to 11 pmol/L at 1 and 2 hours after endotoxin infusion, followed by a gradual increase in FXIa-FXIa inhibitor complexes, measured in the ELISAs, with a summit of 11 to 15 pmol/L at 6 and 24 hours, respectively. In accordance with previous studies, thrombin generation was detected 1 hour after endotoxin infusion to become maximal after 3 to 4 hours. In contrast, we did not find any evidence of contact activation, because markers of activation of prekallikrein and FXII remained undetectable. From the FXIa data a theoretical model was constructed which suggested that inhibition of FXIa does not take place in the plasma compartment, but is localized on a surface. These data provide the first evidence for FXI activation in low-grade endotoxemia and suggest that FXI is activated independently of FXII.

Adult↗

PubMed1998

[Drug treatment of Crohn's disease].

The medical management of Crohn's disease has changed in recent years, but the mainstay of treatment is still prednisone. A substantial fraction of steroid-treated patients are refractory to therapy and addition of azathioprine or methotrexate has a corticosteroid-sparing effect and increases duration of remission. Controlled ileal release budesonide (9 mg daily) induces clinical remission in 60-70% of patients with Crohn's ileitis or right-sided colitis, and continued budesonide treatment has a finite effect on the duration of remission. The efficacy of mesalazine in active Crohn's disease is limited and high doses are required (4000 mg/day). The role of mesalazine in Crohn's disease in remission is disputed, and there is no evidence of a corticosteroid-sparing effect.

Adrenal Cortex Hormones↗

PubMed1998

[Immunology in clinical practice. VIII. Role of cytokines in the pathogenesis of bacterial infections].

Cytokines are small proteins that can be produced by many different cell types involved in inflammation. The cytokine network consists of pro-inflammatory cytokines, facilitating inflammation, and anti-inflammatory cytokines, reducing inflammation at least in part by inhibiting the production of pro-inflammatory cytokines. The production of cytokines is enhanced during bacterial infections. The balance between pro- and anti-inflammatory cytokines critically determines the outcome of infection. Excessive systemic release of pro-inflammatory cytokines such as tumour necrosis factor alpha and interleukin 1 may contribute to organ failure in patients with fulminant sepsis. On the other hand, the local action of pro-inflammatory cytokines, at the site of a compartmentalized infection, is required for an adequate host antibacterial defence. Therefore, neutralization of pro-inflammatory cytokines may benefit some patients with bacterial sepsis but harm others.

Bacterial Infections↗

PubMed1998

Treatment of therapy-resistant perineal metastatic Crohn's disease after proctectomy using anti-tumor necrosis factor chimeric monoclonal antibody, cA2: report of two cases.

PURPOSE: Two young females with well-documented Crohn's disease and nonhealing perineal wounds following proctectomy compatible with "metastatic Crohn's disease" are described. We hypothesized that metastatic Crohn's disease would be a tumor necrosis factor-dependent inflammatory reaction and have treated these two patients with the anti-tumor necrosis factor chimeric monoclonal antibody, cA2. MAIN FINDINGS: Administration of cA2 was followed by a rapid reduction of subjective and objective parameters of inflammation and caused a substantial reduction of the wound size. CONCLUSION: These preliminary data are consistent with a tumor necrosis factor-dependent inflammatory cause of Crohn's disease and its extraintestinal manifestations and provide support for targeting tumor necrosis factor in this condition.

Adult↗

PubMed1998

Peritoneal cytokine release after elective gastrointestinal surgery and postoperative complications.

BACKGROUND: Laparotomy is known to give rise to systemic and local cytokine release. In the present study we investigated the course of the peritoneal response of tumor necrosis factor alpha (TNFalpha), interleukin (IL)-6, and IL-10 after elective gastrointestinal surgery and studied the differences in local cytokine response in patients developing postoperative complications. METHODS: Twelve consecutive patients underwent pancreatoduodenectomy (n = 9) or biliary and gastric bypass (n = 3) for pancreatic carcinoma. Sampling (TNFalpha, IL-6, IL-10) of fluid from abdominal drains was performed at return to the recovery unit (T=0), and at 3, 6, 18, 30, 42, 54, 66, 78 hours. Systemic sampling was performed at T=0, 3, 6, 18, 42, 66 hours. Postoperative cytokine response in patients with and without postoperative complications was compared. RESULTS: In patients without postoperative complications, peritoneal TNFalpha and IL-10 levels decreased in time (P = 0.07 and P = 0.01, respectively), whereas IL-6 did not change significantly during sampling (P = 0.28). Systemic IL-6 and IL-10 levels decreased 10-fold within 66 hours (IL-6, P = 0.04; IL-10, P = 0.06). Four patients experienced postoperative complications. All 4 patients with complications showed a second rise in peritoneal TNFalpha levels preceding the complication. All 4 patients had positive bacterial drain cultures from the abdominal drain, following the TNFalpha rise. CONCLUSIONS: After elective abdominal surgery, cytokines are released into the abdominal cavity. Intra-abdominal complications are accompanied or preceded by a peritoneal TNFalpha rise. In patients after elective gastrointestinal surgery, monitoring of peritoneal TNFalpha might be helpful in the early detection of severe intra-abdominal complications.

Aged↗

PubMed1998

Procoagulant and proinflammatory activity in acute coronary syndromes.

OBJECTIVES: Both the hemostatic and inflammatory system are thought to play a role in the pathogenesis of acute coronary syndromes. However, their respective contribution and interrelationship remain unclear, therefore, we studied the relationship between activation of the coagulation system and proinflammatory activity in ischemic coronary syndromes. METHODS: Thrombin-antithrombin III (TAT), prothrombin fragments F1 + 2, fibrinopeptide A (FPA), interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured in 50 patients with unstable angina (UA), 60 patients with acute myocardial infarction (AMI) and in 50 patients with stable angina (SA). RESULTS: FPA levels were significantly higher in patients with UA and AMI than in patients with SA (p = 0.0015 and p < 0.0001), and were higher in patients with AMI than UA (p = 0.0013). Plasma IL-6 concentrations were significantly higher in patients with UA and AMI than in patients with SA (p = 0.0020 and p < 0.001), and again were higher in AMI than UA (p = 0.001). Interestingly, FPA or IL-6 elevations on admission were found in different patients. In contrast, TAT, F1 + 2 and IL-8 levels were not different between the three groups. CONCLUSIONS: IL-6 and FPA were shown to be independent predictive markers with equal discriminative power to distinguish stable (SA) from unstable (UA + AMI) patients. Moreover, hemostatic and inflammatory markers can be elevated independently in the acute phase of ischemic coronary syndromes.

Angina, Unstable↗

PubMed1998

Minimally invasive surgery induces endotoxin-tolerance in the absence of detectable endotoxemia.

Lipopolysaccharide (LPS) tolerance is characterized by an impaired proinflammatory cytokine production upon restimulation of mononuclear cells with LPS. LPS is considered the primary activator for this phenomenon. In response to major injury and extensive abdominal surgery, an immune reaction comparable to LPS tolerance has been described. Therefore, it was investigated whether primary stimuli other than LPS could induce cytokine downregulation. In eight patients who underwent a laparoscopic cholecystectomy, blood was obtained before and after induction of anaesthesia and 2, 6, and 24 hr postoperatively. Ex vivo stimulation of whole blood resulted in a transient reduction (nadir 2 hr postoperatively) of tumor necrosis factor-alpha, interleukin (IL)-1 beta, and interferon-gamma release, while IL-1 receptor antagonist production increased. Stress hormones, LPS-binding protein, and bactericidal/permeability-increasing protein do not seem to be involved. This study shows that minimally invasive surgery, in the absence of endotoxemia, can induce LPS desensitization. These data suggest that prior endotoxemia is not essential for the development of LPS tolerance.

Acute-Phase Proteins↗

PubMed1998

Endotoxin release and cytokine production in acute and chronic meningococcaemia.

Chronic meningococcaemia is a relatively benign manifestation of meningococcal disease. Whether bacterial virulence factors are responsible for this benign course has not been studied. We compared the in vitro endotoxin-liberating ability and cytokine-inducing potential of 31 Neisseria meninigitidis isolates obtained from children with acute septic shock with that of nine isolates obtained from patients with chronic meningococcaemia and 12 isolates obtained from carriers with respiratory symptoms. The median endotoxin level released in vitro after 3 h of incubation was significantly higher for isolates causing septic shock compared with isolates from the other two groups (P=0.01 and 0.02, Mann-Whitney test). This was not explained by differences in bacterial growth rate in vitro. The median IL-6 levels in whole blood ex vivo after 4 h of incubation were also significantly lower for isolates causing chronic meningococcaemia (P=0.04, Mann-Whitney test). The endotoxin and cytokine levels measured on admission in the 31 children with acute meningococcal septic shock showed a 1000-fold variation. No relationship was established between the amount of endotoxin released by the causative microorganisms in vitro and the endotoxin or cytokine levels in the corresponding 31 children. These results suggest a diminished bacterial virulence for isolates causing chronic meningococcaemia. However, other factors than the endotoxin-releasing potential of the microorganism involved are responsible for the wide variation in endotoxin and therefore cytokine levels in patients with acute meningococcal septic shock.

Adolescent↗

PubMed1998

Phenotypical characterization of cells in the thoracic duct of patients with and without systemic inflammatory response syndrome and multiple organ failure.

The subset composition and recirculation properties of the migrating lymphocyte pool in humans is largely unknown. The present study was conducted in order to phenotypically characterize cells in human thoracic duct lymph of patients under non-inflammatory and inflammatory conditions. These data were compared with data from peripheral blood, with special emphasis on those cells homing to the gut. Thoracic duct lymph and peripheral blood contained comparable proportions of B and T lymphocytes and CD8+ cells. Thoracic duct lymph contained proportionally more CD4+ cells, more CD4+CD45RO+ that express alpha 4 beta 7 cells and more CD8+CD45RO+ that express alpha 4 beta 7, as compared to peripheral blood. These data suggest an equal recirculation rate of B and T lymphocytes; a more active recirculation of CD4+ cells compared to CD8+ cells; and a more active recirculation of memory cells to the gut as compared to other extra-lymphoid sites in patients under non-inflammatory conditions. Data were also obtained in patients with the system inflammatory response syndrome and multiple organ failure. Although it is generally assumed that granulocytes and monocytes do not recirculate, lymph of multiple organ failure patients contained significantly more granulocytes than monocytes, indicating that in severe generalized inflammatory states these cells re-enter the circulation through the thoracic duct. Furthermore, no increased activation of cells homing to the gut was found in these patients.

Aged↗