PubMed Health⌕ Search

Biomedical subjects

C E Hack

Publications and source records attributed to C E Hack.

At least 181 records · Page 10Linked to original sources
PubMed1996

IL-1 beta does not cause neutrophil degranulation but does lead to IL-6, IL-8, and nitrite/nitrate release when used in patients with cancer.

The use of IL-1 in humans is associated with dose-limiting toxicity which resembles that of TNF-alpha or IL-2. Activation of neutrophils is thought to contribute to the toxicity caused by these two cytokines. We studied the effect of IL-1 in vivo on changes in neutrophil numbers and neutrophil degranulation as well as on the formation of neutrophil agonists, such as complement activation products, and on levels of TNF, IL-6, IL-8, and nitrite/nitrate (as a measure of nitric oxide production). Six patients with metastatic melanoma were treated with 3 ng/kg recombinant human IL-1 beta daily. One hour after the start of the 30-min IL-1 infusion, which caused mild cardiovascular toxicity, plasma levels of IL-6 reached a peak of 25 +/- 9 ng/L (mean +/- SEM), IL-8 reached a peak of 311 +/- 100 ng/L at 2 h, and nitrite/nitrate peaked after 10 h to 89 +/- 27 mumol/L. IL-1 did not induce significant changes in plasma levels of TNF or of the complement activation products C3a and C4b/c. Although IL-1 induced neutrophilia, levels of elastase and lactoferrin did not change. The failure of IL-1 to degranulate neutrophils was confirmed in an ex vivo model with whole blood culture in which doses of up to 100 microgram/L IL-1 beta or IL-1 alpha failed to induce significant elastase or lactoferrin release, whereas TNF, tested as a positive control, was able to do so. These results demonstrate that, unlike TNF, IL-1 does not cause neutrophil degranulation in man, despite its ability to cause neutrophilia and the rapid release of IL-6, IL-8, and nitrite/nitrate.

Adult↗
PubMed1996

Early complement components in Alzheimer's disease brains.

Activation products of the early complement components C1, C4 and C3 can be found colocalized with diffuse and fibrillar beta-amyloid (beta/A4) deposits in Alzheimer's disease (AD) brains. Immunohistochemically, C1-esterase inhibitor (C1-Inh) and the C1 subcomponents C1s and C1r can not, or only occasionally, be detected in plaques or in astrocytes. The present finding that C1q, C1s and C1-Inh mRNA are present in both AD and control brains suggests that the variable immunohistochemical staining results for C1r, C1s and C1-Inh are due to a rapid consumption, and that the inability to detect C1s, C1r or C1-Inh is probably due to the dissociation of C1s-C1-Inh and C1r-C1-Inh complexes from the activator-bound C1q into the fluid phase. Employing monoclonal antibodies specific for different forms of C1-Inh, no complexed C1-Inh could be found, whereas inactivated C1-Inh seems to be present in astrocytes surrounding beta/A4 plaques in AD brains. These findings, together with our finding (using reverse transcriptase-polymerase chain reaction) that C1-Inh is locally produced in the brain, suggest that in the brain complement activation at the C1 level is regulated by C1-Inh. Immunohistochemically, no evidence for the presence of the late complement components C5, C7 and C9, or of the membrane attack complex (MAC), was found in beta/A4 plaques. In contrast to the mRNA encoding the early components, that of the late complement components appears to be hardly detectable (C7) or absent (C9). Thus, without blood-brain-barrier impairment, the late complement components are probably present at too low a concentration to allow the formation of the MAC, which is generally believed to be responsible for at least some of the neurodegenerative effects observed in AD. Therefore, the present findings support the idea that in AD, complement does not function as an inflammatory mediator through MAC formation, but through the action of early component activation products.

Aged↗
PubMed1996

Specific complement inhibition with heparin-coated extracorporeal circuits.

BACKGROUND: Although it is well established that heparin-coated extracorporeal circuits reduce complement activation during cardiac operations, little in vivo information is available on the reduction in alternative and classic pathway activation. METHODS: In a prospective, randomized study involving patients undergoing coronary artery bypass grafting with standard full heparinization, we compared heparin-coated circuits (Duraflo II) (10 patients) with uncoated circuits (10 patients) and assessed the extent of initiation of complement activation by detecting iC3 (C3b-like C3) concentrations, classic pathway activation by C4b/c (C4b, iC4b, C4c) concentrations, terminal pathway activation by soluble C5b-9 concentrations, and C3 activation by C3a (C3a desArg) and C3b/c (C3b, iC3b, C3c) concentrations. RESULTS: Heparin-coated extracorporeal circuits significantly reduced circulating complement activation product C3b/c and soluble C5b-9 concentrations at the end of cardiopulmonary bypass and after protamine sulfate administration compared with the uncoated circuits, but not iC3, C4b/c, or C3a concentrations. CONCLUSIONS: Heparin-coated extracorporeal circuits reduce complement activation through the alternative complement pathway, probably at the C3 convertase level, and, consequently, the terminal pathway. C3b/c seems to be a more sensitive marker than C3a to assess complement activation during cardiac operations.

Aged↗
PubMed1996

Critical micelle concentrations and stirring are rate limiting in the loss of lipid mass during membrane degradation by phospholipase A2.

In phospholipid membranes attacked by phospholipase A(2) (PLA(2)), accumulation of degradation products influences the binding affinity as well as the catalytic activity of PLA(2). Such accumulation in its turn depends on the rate of membrane degradation and the efflux of degradation products from the membrane, the latter being influenced by the stirring conditions in the system. This complicated process was investigated with a new ellipsometric technique for in situ measurement of membrane mass in a well-defined flow system. Planar phospholipid bilayers were formed on rotating silicon discs in buffer solution. After the addition of 0.05-100 ng/ml of PLA(2) (from Naja mocambique mocambique) to the buffer, mass desorption could be measured with a precision of 3-5 ng/cm(2), that is, about 1% of the surface mass of a single bilayer. Using radiolabeled phospholipids and thin-layer chromatography, it was verified that only the degradation products desorb from the membrane, which was confirmed by the desorption of mixtures of phospholipids, lysophospholipids, and fatty acids. The rotating disc allows the exact calculation of the mass transfer constant for transport-limited exchange of lipid between fluid and disc surface, as a function of rotation rate. By using the mass transfer constant, the critical micelle concentrations, and the mole fractions of products, desorption kinetics could be fully described. The amount of degraded phospholipid could be continuously monitored as the sum of the product mass still present in the membrane, as inferred from the desorption rate, and the mass already lost from the surface. It is concluded that ellipsometry is a suitable tool for studying the effects of PLA(2) on membranes.

Adsorption↗
PubMed1996

Thrombin-mediated activation of endogenous factor XI in plasma in the presence of physiological glycosaminoglycans occurs only with high concentrations of thrombin.

The variable bleeding tendency associated with a genetic deficiency of factor XI (FXI) and the lack of bleeding disorders in individuals with a genetic deficiency of factor XII (FXII) suggest an alternative mechanism for FXI activation in vivo. Recently, thrombin has been shown to activate FXI. However, in plasma this activation has been shown to occur only with exogenous FXI and a non-physiological cofactor (sulphatides), and the occurrence of this reaction in a plasma environment has been questioned. Using recently developed sensitive assays for FXIa-inhibitor complexes we found thrombin-mediated and FXII-dependent activation of endogenous FXI in plasma in the presence of heparan sulphate, heparin, dermatan sulphate or dextran sulphate. Using heparan sulphate, which is present in the human vascular system, activation of about 1-2% of plasma FXI was observed, however, only after addition of very high amounts (500 nmol/l) of human alpha-thrombin to FXII-deficient plasma (at a 1 to 4 final dilution). We conclude that endogenous FXI in plasma can be activated by thrombin in the presence of various glycosaminoglycans, including the physiological compounds heparan sulphate and dermatan sulphate, but only at very high concentrations of thrombin, corresponding to 100% prothrombin activation in undiluted plasma.

Blood Coagulation↗
PubMed1996

Clearance of human factor XIa-inhibitor complexes in rats.

The serpins C1 esterase inhibitor (C1Inh), antithrombin (AT), alpha 1-antitrypsin (alpha 1AT) and alpha 2-antiplasmin (alpha 2AP) are known inhibitors of coagulation factor XIa (FXIa). Although initial studies suggested alpha 1AT to be the main inhibitor of FXIa, we recently demonstrated C1Inh to be a predominant inhibitor of FXIa in vitro in human plasma. The present study was performed to investigate the plasma elimination kinetics of preformed human FXIa-FXIa inhibitor complexes injected in rats. The amounts of complexes remaining in circulation were measured using enzyme-linked immunosorbent assays. The plasma half-life time of clearance (t1/2) was 98 min for FXIa-alpha 1AT complexes, whereas it was considerably shorter, i.e. 19, 18 and 15 min for FXIa-C1Inh, FXIa-alpha 2AP and FXIa-AT complexes, respectively. Thus, due to this different plasma t1/2, preferentially FXIa-alpha 1AT complexes may be detected in clinical samples. Furthermore, measuring FXIa-FXIa inhibitor complexes in patient samples may not help to clarify the relative contribution of the individual serpins to inactivation of FXIa in vivo.

Animals↗
PubMed1996

Interleukin 10 release during endotoxaemia in chimpanzees: role of platelet-activating factor and interleukin 6.

Interleukin (IL-)10 has been demonstrated to inhibit endotoxin-induced production of a number of pro-inflammatory cytokines. The present study sought to compare the appearances in the circulation of IL-10, IL-6 and IL-8, and to assess the roles of endogenously produced platelet-activating factor (PAF) and IL-6 in IL-10 release during endotoxaemia in chimpanzees. Intravenous injection of endotoxin (lot EC-5, 4 ng/kg, n = 8) induced a transient rise in serum IL-10 concentrations, peaking after 2 h (213 +/- 70 pg/ml; P < 0.05). No correlations existed between peak IL-10 levels, and peak IL-6 and IL-8 levels. Neither infusion of the specific PAF antagonist TCV-309 (n = 4), nor infusion of a neutralizing anti-IL-6 monoclonal antibody (n = 4) influenced endotoxin-induced IL-10 release. IL-10 release elicited by injection of endotoxin is not mediated by PAF or IL6.

Animals↗
PubMed1996

Activation of the complement, coagulation, fibrinolytic and kallikrein-kinin systems during attacks of hereditary angioedema.

Five patients with hereditary angioedema (HAE) were studied during attacks and remission as were healthy controls. The high levels of C1/C1-INH complexes, low C4 and high ratio C4 activation products (C4bc)/C4 also differed significantly during remission compared to controls. During attacks C4bc/C4 increased (922-2007; P = 0.022, remission versus attacks, median values throughout), C2 and CH50 dropped (111-31%; P = 0.043 and 110-36%; P = 0.016, respectively), TCC (C5b-9) increased (0.88-1.23 AU/ml; P = 0.028). Cleavage of HK increased to be almost complete during attacks (20-90%; P = 0.009). While factor XIa/serpin-complexes did not increase, a more than twofold rise in thrombin/antithrombin-complexes (0.20-0.50 microgram/l; P = 0.009) and in plasmin/alpha-2-antiplasmin-complexes (7.3-17 nmol/l; P = 0.028) was observed. For the first time cascade activation in HAE was studied simultaneously, and corroborates that attacks lead to activation of the kallikrein-kinin system, fibrinolysis and early part of the classical complement pathway. In addition, the authors present novel data of terminal complement and coagulation activation, the latter apparently not via FXIa.

Angioedema↗
PubMed1996

Increased numbers of granzyme-B-expressing cytotoxic T-lymphocytes in the small intestine of HIV-infected patients.

The objective of this study was to determine whether granzyme B-expressing cells, which identify activated cytotoxic lymphocytes, are present in the small intestinal mucosa of human immunodeficiency virus (HIV)-infected patients with and without diarrhea. Therefore, duodenal biopsy specimens from 29 HIV-infected patients (11 with diarrhea and 18 without diarrhea) and 15 control patients were stained for the presence of granzyme B expressing cells. In HIV-infected patients, a significantly increased expression of granzyme B in the lamina propria was observed (p = 0.00001): In 22 of 29 patients, at least 5-10 cells per high-power field were counted. In contrast, in 13 of 15 control patients, granzyme B was not expressed or minimally so, and in two others a maximum of five granzyme-B-expressing cells could be detected per high-power field. No significant difference was found between the HIV-infected patients with and without diarrhea. Double staining revealed that the granzyme-B-expressing cells were mainly CD3 positive. These data show that activated cytotoxic T lymphocytes (CTLs) are present in the duodenal mucosa of HIV-infected patients. No relation between the number of CTLs and the presence of diarrhea was demonstrated. CTLs are known to be involved in the pathogenesis of HIV infection and in the production of tissue injury, but their functional role in intestinal HIV-related pathology has yet to be elucidated.

Adult↗
PubMed1996

OKT3-induced nephrotoxicity is associated with release of group II secretory phospholipase A2.

Administration of the murine IgG2a CD3 monoclonal antibody OKT3 exerts a transient nephrotoxic effect. Increased levels of group II secretory phospholipase A2 (sPLA2-II) might account for this nephrotoxicity as sPLA2-II induces the biosynthesis of prostaglandins, vasoactive lipid mediators that influence glomerular haemodynamics and renal function. Furthermore, extracellular phospholipases seem to be involved in proximal tubular cell injury. We studied plasma sPLA2-II levels in relation to circulating creatinine, tumour necrosis factor alpha, interleukin 6 and C-reactive protein levels in 15 renal allograft recipients receiving rejection treatment with OKT3. As a control group, we studied 15 renal allograft recipients receiving rejection treatment with methylprednisolone. A maximal fourfold increase in sPLA2-II levels was observed 48 h after the first OKT3 administration, preceded by increased tumour necrosis factor alpha and interleukin 6 levels and accompanied by increased C-reactive protein levels. Creatinine levels reached a maximal increase 72 h after initiation of treatment. During methylprednisolone treatment no increase in any of the studied parameters was observed. Thus, administration of OKT3 induces increased sPLA2-II levels, presumably via generation of cytokines. We hypothesize that sPLA2-II may contribute to the nephrotoxic effect of OKT3 by inducing vasoconstrictive prostaglandins and renal tubular cell injury.

Adolescent↗
PubMed1996

Tumor necrosis factor unresponsiveness after surgery in bile duct-ligated rats.

In obstructive jaundice, postoperative complications are related to gut-derived endotoxemia and possibly mediated by cytokines such as tumor necrosis factor (TNF) and interleukin-6 (IL-6). This study investigated the course of IL-6 and TNF after surgery in bile duct-ligated rats (BDL) treated with and without an enteral endotoxin binder (cholestyramine). Endotoxin in rat plasma was determined by blocking cytokine production in whole blood cell cultures stimulated by rat plasma using antibodies directed against the endotoxin (CD14) receptor. Surgery elicited a significant IL-6 response in saline-treated BDL rats (BDL-SAL). TNF, however, remained at its low preoperative levels. Cholestyramine treatment resulted in undetectable preoperative TNF and IL-6 levels, but levels of both cytokines were significantly raised after surgery. Endotoxin, as determined by the CD14 blockade test, was identified in the BDL-SAL group, before (time 0) and after surgery (2 and 4 h), whereas in the cholestyramine group endotoxin was only present at 2 h after surgery. The lack of a postoperative plasma TNF response in the BDL-SAL group in the continuous presence of endotoxin suggests endotoxin tolerance for TNF production in obstructive jaundice.

Animals↗
PubMed1996

Interleukin-8 in airway inflammation in patients with asthma and chronic obstructive pulmonary disease.

We have investigated whether IL-8 is present in airway secretions from patients with asthma and chronic obstructive pulmonary disease (COPD) to obtain information on its possible role in airway inflammation in obstructive airways disease. In the bronchoalveolar lavage fluid (BALF) from 11 clinically stable patients with asthma the levels of IL-8 were increased compared to 10 healthy subjects (median: controls 21.5 pg/ml, asthma 244 pg/ml: p < 0.005). In the patients with asthma the levels of IL-8 correlated with the percentage neutrophils in the BALF (r = 0.81; p < 0.001) and with a parameter of the permeability of the respiratory membrane, the quotient (alpha 2-macroglobulin in BALF)/(alpha 2-macroglobulin in serum) (r = 0.66; p < 0.025). In the sputum sol phase of 9 patients with symptomatic asthma the levels of IL-8 were lower than in 9 patients with COPD (asthma: 6.4 ng/ml; COPD: 16.3 ng/ml; p < 0.02) and significantly correlated with those of neutrophilic myeloperoxidase (MPO; r = 0.85; p < 0.005). The increased levels of IL-8 in the airway secretions from both patients with asthma and COPD may be markers of an ongoing inflammatory process, which is more pronounced in patients with COPD. In patients with asthma the strong correlation between the levels of IL-8 and the percentage neutrophils and/or the levels of MPO points to a role of IL-8 in the recruitment and activation of neutrophils in the airway lumen.

Adolescent↗
PubMed1996

Factor XIa induced activation of the intrinsic cascade in vivo.

Coagulation factor XI is a glycoprotein of the contact factor system. Its deficiency is associated with a highly variable bleeding tendency, thus a role in relation to hemostasis appears to exist. However, the importance of factor XI for stimulating intrinsic coagulation in vivo has not yet been determined. To study the procoagulant effects of human factor XIa in vivo, we infused the purified enzyme into normal chimpanzees (100 micrograms) in the absence or presence of the thrombin inhibitor rec-hirudin (1.0 mg/kg loading dose plus 0.3 mg/kg body wt continuous infusion). Factor XIa elicited an immediate activation of factors IX, X, and prothrombin, as measured by their respective activation fragments. However, whereas the activation of factors IX and X was immediate and shortlasting, (peak increments of 6- and 1.4-fold of baseline at 5 minutes after injection), the conversion of prothrombin gradually increased, reaching a summit of 6-fold baseline values after 60 min, and remaining elevated during the course of the experiments. Thrombin-antithrombin complexes also remained elevated during the study period. In the presence of hirudin, the initial activation of factors IX, X, and prothrombin was unchanged, however the further increment in prothrombin fragment F1 + 2 was markedly inhibited. These results demonstrate that factor XIa is a potential agonist of the intrinsic cascade in vivo, which activity is enhanced in the presence of thrombin.

Analysis of Variance↗
PubMed1996

Nafamostat mesilate, a broad spectrum protease inhibitor, modulates platelet, neutrophil and contact activation in simulated extracorporeal circulation.

Activation of humoral and cellular participants in inflammation enhances the risk of postoperative bleeding and multiple organ damage in cardiopulmonary bypass (CPB). We now compare the effects of heparin alone in combination with nafamostat mesilate (NM), a protease inhibitor with specificity of trypsin-like enzymes, in an extracorporeal circuit which simulates CPB. NM significantly inhibits the release of platelet beta-thromboglobulin (beta TG) at 60 and 120 min. Platelet counts do not differ. ADP-induced aggregation decreases in circuits with NM, which is due to a direct effect of NM on platelet function. NM prevents any significant release of neutrophil elastase; at 120 min, plasma elastase-alpha 1-antitrypsin complex is 0.16 micrograms/ml in the NM group and 1.24 micrograms/ml in the control group. NM completely inhibits formation of complexes of C1 inhibitor with kallikrein and FXIIa. NM does not alter markers of complement activation (C1-C1-inhibitor complex and C5b-9), or indicators of thrombin formation (F1.2). However, at 120 min, thrombin activity as measured by release of fibrinopeptide A is significantly decreased. The data indicate that complement activation during CPB correlates poorly with neutrophil activation and that either kallikrein or FXIIa or both may be more important agonists. The ability of NM to inhibit two important contact system proteins and platelet and neutrophil release raises the possibility of suppressing the inflammatory response during clinical CPB.

Anticoagulants↗
PubMed1996

Fat emulsion infusion potentiates coagulation activation during human endotoxemia.

Intravenous fat emulsions are frequently given to malnourished patients who are prone to suffer from infectious complications. As injection of low dose endotoxin represents a model to study the human response to acute infection, we sought to determine the effect of lipid emulsion infusion on endotoxin-induced activation of the hemostatic mechanism in man. Ten healthy men received a bolus intravenous injection of endotoxin (lot EC-5; 20 U/kg) midway through a 4-h infusion (125 ml/h) of either dextrose 5% (n = 5) or Intralipid 20% (n = 5). Lipid infusion potentiated endotoxin-induced coagulation activation, as indicated by higher plasma levels of the prothrombin fragment F1 + 2 and of thrombin-antithrombin III complexes (both p < 0.05 for the difference between groups). However, lipid infusion did not influence the fibrinolytic response to intravenous endotoxin, as reflected by similar increases in the levels of tissue-type plasminogen activator and plasmin-alpha 2-antiplasmin complexes in both groups. Endotoxin-induced appearance of plasminogen activator inhibitor type I was enhanced by lipid infusion (p < 0.05). These data suggest that fat emulsion infusion may enhance the tendency towards thrombotic complications in patients with infections.

Adult↗
PubMed1996

Fibrinolytic response to interferon-alpha in healthy human subjects.

Interferons (IFNs) are used for a variety of disorders. It has been postulated that part of the effects of IFN may be mediated by IFN-induced modulation of endothelial cells. Since the principal activating and inhibiting factors of the fibrinolytic system are synthesized and stored in endothelial cells, we have studied the effects on fibrinolysis and coagulation of the administration of recombinant IFN-alpha (5 x 10(6) U/m2) to healthy human subjects (n = 8) in a randomized controlled cross-over study. IFN-alpha significantly increased plasma levels of tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA). Simultaneously, plasma levels of the inhibitor of plasminogen activation, PAI-1, sharply increased. The net effect on plasma plasminogen activator activity (PA-activity) was a modest increase to 116% of baseline, however without a significant effect on plasmin generation, as reflected by plasma levels of plasmin-alpha 2-antiplasmin complexes. IFN-alpha had no effect on the plasma levels of thrombin-antithrombin III (TAT) complexes. We conclude that despite considerable effects on endothelial cells, IFN-alpha does not significantly alter the coagulant-fibrinolytic balance, although the occurrence of such changes under pathological circumstances is not excluded.

Adult↗