A new easy method for specific measurement of active myeloperoxidase in human biological fluids and tissue extracts.

The SIEFED ("Specific Immunological Extraction Followed by Enzymatic Detection") method already developed for the specific detection of the activity of equine myeloperoxidase (MPO) was adapted for the specific measurement of active human MPO in biological fluids or tissue extracts. The method consists of the extraction of MPO from aqueous solutions by immobilized anti-MPO antibodies followed by a washing (to eliminate the extraction medium and the biological fluid with their possible interfering molecules) and the measurement of the activity of MPO with a detection system containing a fluorogenic substrate, H(2)O(2) and nitrite ions as reaction enhancer. The SIEFED was applied to study active MPO in human biological fluids (plasma, bronchoalveolar lavage fluid and supernatant from carotids extracts). The SIEFED for human MPO has a sensitivity limit of 0.080 mU/mL and showed good precision with intra- and inter-assay coefficients of variation below 10 and 20% respectively within a broad range of MPO activities establish from 0.156 to 473 mU/mL. The SIEFED for human MPO will be useful for the specific detection of active MPO in complex fluids and can be complementary to an ELISA to determine an active/total MPO ratio in healthy volunteers and patients especially in case of chronic or acute inflammatory diseases.

Nitric oxide-related products and myeloperoxidase in bronchoalveolar lavage fluids from patients with ALI activate NF-kappa B in alveolar cells and monocytes.

An increased production of NO* and peroxynitrite in lungs has been suspected during acute lung injury (ALI) in humans, and recent studies provided evidence for an alveolar production of nitrated compounds. We observed increased concentrations of nitrites/nitrates, nitrated proteins and markers of neutrophil degranulation (myeloperoxidase, elastase and lactoferrine) in the fluids recovered from bronchoalveolar lavage fluids (BALF) of patients with ALI and correlated these changes to the number of neutrophils and the severity of the ALI. We also observed that BALFs stimulated the DNA-binding activity of the nuclear transcription factor kappa B (NF-kappaB) as detected by electrophoretic mobility shift assay in human alveolar cells (A549) and monocytes (THP1). The level of activation of the NF-kappaB-binding activity was correlated to the concentration of nitrated proteins and myeloperoxidase. Furthermore, in vitro studies confirmed that NO*-derived species (peroxynitrite and nitrites) and the neutrophil enzyme myeloperoxidase by themselves increased the activation of NF-kappaB, thereby arguing for an in vivo pathogenetic role of NO*-related products and neutrophil enzymes to human ALI.

Bronchoalveolar lavage fluids of ventilated patients with acute lung injury activate NF-kappaB in alveolar epithelial cell line: role of reactive oxygen/nitrogen species and cytokines.

In human alveolar epithelial cell line, we investigated the binding activity of NF-kappaB induced by the bronchoalveolar lavage fluids (BALs) from ventilated patients with acute lung injury (ALI), in correlation with the concentrations of inflammatory cytokines, RNOS, and the severity of the ALI. In BALs obtained in 67 patients (16 bronchopneumonia, 14 infected ARDS, 20 ARDS, and 17 ALI patients without bronchopneumonia and no ARDS), we measured endotoxin, IL-1beta, IL-8, and nitrated proteins (NTP), the activity of myeloperoxidase, and the capacity to activate the NF-kappaB in alveolar A549 cells by electrophoretic mobility shift and supershift assays. The neutrophil counts and mean IL-1beta, IL-8, myeloperoxidase, and NTP values were increased in bronchopneumonia and infected ARDS groups compared to ARDS and ALI without bronchopneumonia and no ARDS groups (P<0.001). The number of neutrophils was correlated to those of IL-1beta, IL-8, myeloperoxidase, NTP, and endotoxin in all groups (P<0.0001). NF-kappaB activity was induced in alveolar like cells by BALs in all groups, was higher in bronchopneumonia and infected ARDS groups (P<0.02), and was correlated to IL-1beta (P=0.0002), IL-8 (P=0.02), NTP (P=0.014), myeloperoxidase (P=0.016), and neutrophil counts (P=0.003). BALs of bronchopneumonia and infected ARDS patients had increased inflammatory mediators (compared to ARDS and ALI without bronchopneumonia and no ARDS patients) that correlated to neutrophil counts and to the NF-kappaB-binding activity. These mediators and NF-kappaB activation may induce an amplification of inflammatory phenomena. By in vitro studies, we confirmed that NO-derived species (10(-6) to 10(-5)M peroxynitrite and 10(-5)M nitrites) and myeloperoxidase (at concentration equivalent to that found in BALs) can participate in the NF-kappaB activation.

Bronchoalveolar lavage fluids of patients with lung injury activate the transcription factor nuclear factor-kappaB in an alveolar cell line.

In bronchoalveolar lavage (BAL) fluid from ventilated patients, cytotoxic oxidant activity is correlated with neutrophil activation. The aim of the present study was to investigate the hypothesis that BAL fluid induces activation of the transcription nuclear factor-kappaB (NF-kappaB) in human alveolar cells, in correlation with inflammatory mediators. We measured endotoxin, inflammatory cytokines [interleukin-1beta (IL-1beta), IL-8], nitrated proteins and the activity of myeloperoxidase (MPO) in BAL fluid from ventilated patients developing bronchopneumonia ( n =19 samples) or with acute respiratory distress syndrome (ARDS) ( n =14), and from ARDS/infection-free patients ( n =11). We also exposed alveolar cells to the BAL fluid or to human MPO, H(2)O(2) or HOCl, and tested nuclear extracts for the activation of NF-kappaB. IL-1beta, IL-8, nitrated protein, MPO and endotoxin levels were significantly higher in BAL fluid from patients with bronchopneumonia than in that from the ARDS and ARDS/infection-free groups. A correlation was observed between IL-8 and MPO values ( r =0.82). The level of NF-kappaB activity induced by the BAL fluid was correlated with levels of IL-1beta ( P <0.001), IL-8 ( P <0.005) and MPO ( P <0.002), and with the neutrophil count ( P <0.002), and was higher for BAL fluid from the bronchopneumonia group. NF-kappaB activation by MPO was also demonstrated. The activation of NF-kappaB by BAL fluid, especially that from bronchopneumonia patients, suggests that a similar phenomenon may occur in vivo, leading to potential amplification of the inflammatory reaction.

Oxidative processes in human promonocytic cells (THP-1) after differentiation into macrophages by incubation with Chlamydia pneumoniae extracts.

Human monocytes differentiated into macrophages by Chlamydia pneumoniae were able to oxidize blood lipoproteins, as discovered by Kalayoglu et al. (1998). Using a model of human promonocytic cells (THP-1), the cells were differentiated into macrophages by preincubation with C. pneumoniae extract, and further stimulated by phorbol myristate acetate. In these conditions, the differentiated cells oxidized a thiol compound and released superoxide anion as demonstrated respectively by gas liquid chromatography and electron spin resonance. The thiol oxidation and superoxide anion release were inhibited by diphenyliodonium, a NADPH oxidase and NOsynthase inhibitor, proving that the respiratory burst and the NOsynthase were involved in the oxidation processes occurring in the differentiated THP-1. The role of H(2)O(2) (derived from superoxide anion) was indicated by the enhancing effect of a peroxidase on the thiol oxidation. The presence of alpha-tocopherol in the surrounding medium strongly diminished the oxidation of the thiol target.

Nitrated proteins in bronchoalveolar lavage fluid of patients at risk of ventilator-associated bronchopneumonia.

The study was designed to identify markers of oxidative injury, related to the nitric oxide derived cascade, in bronchoalveolar lavage (BAL) fluid from intensive care patients suspected of ventilator-associated pneumonia (VAP) and/or acute respiratory distress syndrome (ARDS). Thirty-eight patients developing VAP and/or ARDS (VAP/ARDS group) were compared to 20 ventilated patients without VAP/ARDS (control group). Myeloperoxidase (MPO) and elastase, taken as markers of neutrophil activation were measured by enzymatic techniques, and nitrated proteins (NTPs) by an immunological method. The cytotoxicity of the BAL fluid was tested using cultured human epithelial alveolar cells by the release of pre-incorporated 51Cr. Mean NTP concentration and, MPO and elastase activities were different between the VAP/ARDS and control groups (p<0.05 for NTPs; p<0.005 for MPO; p<0.005 for elastase). NTP concentration correlated with MPO and elastase activity and neutrophil number (r=0.93, 0.91 and 0.87, respectively), but not to protein concentration and arterial oxygen tension/inspiratory oxygen fraction. The cytotoxicity of BAL correlated with NTP concentration (r=0.92) and MPO activity (r=0.89). It was concluded that the concentrations of nitrated proteins in bronchoalveolar lavage fluid correlated with the oxidant activity of neutrophils and that, bronchoalveolar lavage fluid cytotoxicity was correlated with the nitrated protein concentration and may be mediated by oxidants.

Correlation between endotoxin level and bacterial count in bronchoalveolar lavage fluid of ventilated patients.

OBJECTIVE: To assess the predictive value of the endotoxin level in the bronchoalveolar lavage (BAL) and to propose to the clinician a guide in the diagnosis of gram-negative bacterial (GNB) pneumonia. DESIGN: Retrospective and prospective studies to investigate the relation between endotoxin level and quantitative bacterial culture of BAL and to test the predictive value of a defined threshold. SETTING: University hospital general intensive care unit. PATIENTS: In the first part of the study, 77 consecutive ventilated patients with clinical suspicion of nosocomial pneumonia between January 1995 and January 1996. In the second part of the study, 93 consecutive ventilated patients studied prospectively between February 1996 and April 1997. MEASUREMENTS AND MAIN RESULTS: Quantitative cultures for aerobic bacteria were performed directly from the fluid. Bacterial species were determined with standard techniques. The detection of endotoxin in BAL was made using a quantitative chromogenic Limulus assay. In the retrospective analysis, a significant correlation between quantitative GNB cultures and BAL endotoxin levels was observed (r2 = 0.60, p < .0001). An endotoxin level > or = 4 endotoxin units/mL (EU/mL) distinguishes patients with a significant GNB count from colonized patients with a sensitivity of 92.6%, a specificity of 81.4% and a correct classification rate of 84.9%. In the prospective analysis, the 4 EU/mL threshold permits identification of infected patients with a sensitivity of 82.2%, a specificity of 95.6%, and a correct classification rate of 90.3%. The receiver operating characteristic curve analysis showed that the Limulus assay still had a good discrimination power in the prediction of significant bacterial count in BAL fluid. CONCLUSIONS: Endotoxin detection immediately after bronchoscopy is a distinct advantage to the clinician because antimicrobial gram-negative therapy may be immediately justified according to the results.

The visualization and evaluation of bone architecture in the rat using three-dimensional X-ray microcomputed tomography.

Microcomputed tomography allows the true three-dimensional structure of bone to be assessed by a nondestructive analysis. This article describes how this technique has for the first time been applied to rat bone to determine the effects of aging, ovariectomy, and antiresorptive drugs on bone structure and how these results compare with those determined by histological and histomorphometric techniques. During the procedure, a micro X-ray source is directed toward the bone sample. Modifications in the X-ray beam induced by bone crystals are determined for a range of acquisitions before three-dimensional reconstruction of bone architecture is performed. Morphometric parameters determined were trabecular bone volume/tissue volume, trabecular number, and trabecular thickness. The results show that ovariectomy has a dramatic effect on rat bone structure. Following treatment with the bone resorption inhibitor tiludronate, the morphometric parameters were significantly improved. The results obtained with three-dimensional microcomputed tomography were in agreement with observations made using classical techniques. Microcomputed tomography should prove useful for evaluating the antiresorptive effects of bisphosphonates on bone architecture and in allowing between-drug comparisons.

Irbesartan reduces QT dispersion in hypertensive individuals.

Angiotensin type 1 receptor antagonists have direct effects on the autonomic nervous system and myocardium. Because of this, we hypothesized that irbesartan would reduce QT dispersion to a greater degree than amlodipine, a highly selective vasodilator. To test this, we gathered electrocardiographic (ECG) data from a multinational, multicenter, randomized, double-blind parallel group study that compared the antihypertensive efficacy of irbesartan and amlodipine in elderly subjects with mild to moderate hypertension. Subjects were treated for 6 months with either drug. Hydrochlorothiazide and atenolol were added after 12 weeks if blood pressure (BP) remained uncontrolled. ECGs were obtained before randomization and at 6 months. A total of 188 subjects (118 with baseline ECGs) were randomized. We analyzed 104 subjects who had complete ECGs at baseline and after 6 months of treatment. Baseline characteristics between treatments were similar, apart from a slight imbalance in diastolic BP (irbesartan [n=53] versus amlodipine [n=51], 99.2 [SD 3. 6] versus 100.8 [3.8] mm Hg; P=0.03). There were no significant differences in BP normalization (diastolic BP <90 mm Hg) between treatments at 6 months (irbesartan versus amlodipine, 80% versus 88%; P=0.378). We found a significant reduction in QT indexes in the irbesartan group (QTc dispersion mean, -11.4 [34.5] milliseconds, P=0.02; QTc max, -12.8 [35.5] milliseconds, P=0.01), and QTc dispersion did not correlate with the change in BP. The reduction in QT indexes with amlodipine (QTc dispersion, -9.7 [35.4] milliseconds, P=0.06; QTc max, -8.6 [33.2] milliseconds, P=0.07) did not quite reach statistical significance, but there was a correlation between the change in QT indexes and changes in systolic BP. In conclusion, irbesartan improved QT dispersion, and this effect may be important in preventing sudden cardiac death in at-risk hypertensive subjects.

Study of the protective effects of hyperimmune immunoglobulins G and M against endotoxin in mice and rats.

We prepared solutions of human IgM and IgG to various lipopolysaccharide (LPS) species. These were then tested, along with solutions of non-LPS specific human IgG or IgM, for their ability to confer passive immunity against experimental endotoxemia in two animal models. The immunoglobulins were first tested for an effect on the lethality induced by seven different LPSs in actinomycin-D sensitized mice, or by three different bacteria in normal mice. When the immunoglobulins were administered 1 h before challenge, a small protective effect was observed. This protection was dependent upon both the anti-LPS agent, the chemical composition of the LPS, or the strain of gram-negative bacteria used for injection. The anti-LPS IgM and IgG preparations reduced the mortality induced by Escherichia coli but not by Serratia marcescens or Klebsiella pneumoniae, indicating protection by strain-specific antibodies. When the antibodies were preincubated with LPS or bacteria for 30 min before administration, almost complete protection was seen. The influence of these immunoglobulin preparations or of human albumin (as a control) on the hypotensive and vascular-permeabilizing effects of LPS in rats was then studied. A dose-dependent inhibitory effect was observed with IgG preparations and albumin. At 200 mg/kg, anti-LPS IgG reduced the effects of LPS, while at 400 mg/kg, both anti-LPS and normal IgG preparations showed protection, as did human albumin used at the same dose. The IgM-enriched preparation worsened the initial hypotensive phase after LPS, whereas the anti-LPS IgM significantly reduced the second phase of the hypotension, but only at the largest dose of 400 mg/kg. In this second model using the rat, a clear difference between the activity of IgG and IgM was thus observed. We conclude that pretreatment with human immunoglobulins from large plasma pools modestly, but significantly, attenuated the effects of murine and rat Gram-negative sepsis, but that protection was incomplete. Our results suggest that single regimen intervention strategies may not be sufficient to influence the course of the disease.

Influence of human anti-lipopolysaccharide immunoglobulins on tissue distribution and clearance of lipopolysaccharide in rats.

To examine the influence of passive immunization on the biological fate of injected lipopolysaccharide (LPS), we used a human IgG preparation (anti-LPS IgG) rich in antibodies to a large panel of smooth and rough purified LPS extracts as well as a normal IgG preparation (standard IgG). Our approach was to compare the uptake of 125I-labeled LPS by the tissues of saline or IgG-treated rats. After intravenous injection, one fraction of 125I-labeled Escherichia coli O55:B5 LPS is rapidly taken up by tissues, while another fraction remained in the blood. Uptake of 125I-labeled LPS was principally observed into the liver and spleen. In rats treated prophylactically with standard IgG, these tissues accumulated significantly larger amount of LPS than the tissues of rats treated with anti-LPS IgG. Nevertheless, both IgG preparations increased the specific binding of LPS by the liver and spleen. High levels of homologous unlabeled LPS decreased the uptake of LPS by the liver, presumably by occupying tissue receptors, whereas in the presence of E. coli O127:B8 LPS, an increase of the uptake of 125I-labeled LPS by the liver and lungs was observed. The pharmacokinetics and tissue distribution of LPS-IgG complexes pre-formed in vitro were compared. In the presence of standard IgG, a unexpected increase of the uptake of LPS by the tissues was recorded, whereas LPS-anti-LPS IgG complexes decreased the binding of 125I-labeled LPS to the tissues. On the other hand, the vascular effects induced by LPS did not appear to be modified in rats pretreated with either IgG preparation. In conclusion, although passive immunization against LPS slightly modified the uptake and clearance of LPS, neither in vitro nor in vivo formation of LPS-anti-LPS IgG complexes afforded a very significant protection against the toxic effects of LPS.

A randomised, double-blind comparison of the angiotensin II receptor antagonist, irbesartan, with the full dose range of enalapril for the treatment of mild-to-moderate hypertension.

OBJECTIVE: To compare the anti-hypertensive efficacy, safety, and tolerability of irbesartan with those of the full dose range of enalapril in patients with mild-to-moderate hypertension. DESIGN AND METHODS: A total of 200 patients were randomised to irbesartan 75 mg or enalapril 10 mg (once daily). Doses were doubled at Weeks 4 and/or 8 if seated diastolic blood pressure (DBP) was > or = 90 mm Hg. Trough blood pressure was measured after completion of a 4- to 5-week placebo lead-in period and again after 2, 4, 8, and 12 weeks of treatment. MAIN OUTCOME MEASURES: Efficacy was evaluated by determining the change from baseline in trough seated blood pressure and the proportion of patients normalised (seated DBP <90 mm Hg) at Week 12. Safety and tolerability were assessed by adverse events reported by physicians, by patients in response to a specific-symptoms questionnaire, by open-ended questioning of patients by physicians, and by clinical laboratory evaluations. RESULTS: Both treatments significantly lowered blood pressure with no significant difference in efficacy between treatment groups. At Week 12, the percentage of patients titrated to either enalapril 40 mg or irbesartan 300 mg was 24% and 28%, respectively. The frequency of overall adverse events was similar in both groups. The incidence of cough in the enalapril and irbesartan groups was 17% and 10%, respectively. In contrast to other AII receptor antagonists, there was no change in uric acid concentrations with irbesartan. CONCLUSIONS: Irbesartan was as effective as the full dose range of enalapril. Irbesartan also demonstrated an excellent tolerability profile.

Endotoxaemia, production of tumour necrosis factor alpha and polymorphonuclear neutrophil activation following strenuous exercise in humans.

To examine whether endotoxaemia accompanying long-term, strenuous physical exercise is involved in exercise-induced increase in plasma tumour necrosis factor alpha (TNF-alpha) concentration and polymorphonuclear neutrophil (PMN) activation, 14 male recreational athletes [mean age 28 (SEM 1) years] were studied. Exercise consisted of a 1.5-km river swim, a 40-km bicycle race, and a 10-km road race. Mean time to complete the race was 149.8 (SEM 4.8) min. The plasma concentrations of granulocyte myeloperoxidase (MPO) and TNF-alpha were significantly higher than baseline values immediately and 1 h after exercise (P<0.001). Both variables returned to pre-race levels the day after exercise. Marked, transient decreases in plasma concentrations of anti-lipopolysaccharide (LPS) immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies directed against a panel of selected smooth gram-negative LPS were observed after the race, reaching in most cases minimal values in the blood sample drawn immediately following the completion of the triathlon. There was no significant correlation between the magnitude of PMN activation, as assessed by the increase in plasma concentrations of MPO, and the humoral markers of endotoxaemia and TNF-alpha. An inverse, highly significant relationship between the increase in plasma TNF-alpha concentrations and the changes in circulating anti-LPS IgM antibodies concentrations was observed (r = -0.7; P<0.01). These findings suggest that exercise-induced endotoxaemia was involved in the release of TNF-alpha, that the magnitude of the TNF-alpha response to exercise was down-regulated by anti-LPS antibodies of the IgM class, and that the production of TNF-alpha and endotoxaemia did not seem to play a role in the activation of circulating PMN in the exercising subjects.

Possible in vivo tolerance of human polymorphonuclear neutrophil to low-grade exercise-induced endotoxaemia.

To address the question of whether translocation of bacterial lipopolysaccharide (LPS) into the blood could be involved in the process of exercise-induced polymorphonuclear neutrophil (PMN) activation, 12 healthy male subjects who took part in a sprint triathlon (1.5 km river swim, 40 km bicycle race, 10 km road race) were studied. While there was no detectable amount of endotoxin in the blood samples drawn at rest, exercise was followed by the appearance of circulating endotoxin molecules at the end of competition in four subjects, and after one and 24 h recovery in three and seven athletes, respectively. The concentrations of plasma granulocyte myeloperoxidase ([MPO]), were significantly higher immediately after exercise and one hour later-than baseline values (P<0.001). This variable returned to pre-race levels the day after exercise, despite the presence of detectable amounts of LPS, at that time, in seven athletes. The absence of significant correlation (r=0.26; P=0.383) and temporal association between [MPO] and plasma endotoxin levels led us to conclude that endotoxaemia was not involved in the process of exercise-induced PMN degranulation observed in our subjects.

Mild endotoxaemia and the inflammatory response induced by a marathon race.

1. To address the question of whether endotoxaemia could be involved in the inflammatory response induced by long-term strenuous exercise, 18 male marathon runners [mean age 41 +/- 2 (SEM) years] were studied. Their performance in the marathon ranged from 2 h 46 min to 4 h 42 min. 2. Four venous blood samples were drawn: at rest, just before the race (baseline); within 15 min following the completion of the marathon; after 1 h of recovery; and the morning after the race. 3. The following humoral markers of the inflammatory response to exercise were measured: polymorphonuclear myeloperoxidase (MPO), anaphylatoxin C5a (C5a), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Plasma endotoxin was measured by a sensitive and rapid chromogenic Limulus assay. All inflammatory markers were significantly increased (P < 0.001) after the race, reaching in most cases peak values in the first blood sample drawn following the completion of the marathon [MPO, 298 +/- 19 ng/ml (SEM); C5a, 1.45 +/- 0.32 ng/ml; TNF-alpha, 20 +/- 3 pg/ml; IL-6, 88 +/- 13 pg/ml] when compared with baseline [MPO, 146 +/- 16 ng/ml (SEM); C5a, 0.27 +/- 0.2 ng/ml; TNF-alpha, 12 +/- 1.5 pg/ml: IL-6, 1.0 +/- 0.5 pg/ml]. Traces of plasma endotoxin (ranging from 5 to 13 pg/ml, with one exceptionally high value of 72 pg/ml measured in one runner) were detected in seven subjects within the first hour of recovery. An ELISA method was used to determine the endogenous IgG antibodies toward a range of Gram-negative bacterial lipopolysaccharides (LPSs) of different sizes and structures. A transient decrease in certain anti-LPS activities, mainly against rough LPS, occurred in most cases in the first blood sample drawn after the race. There was no correlation between the magnitude of the inflammatory response to exercise, as assessed by the increase in blood levels of humoral markers of inflammation, and the changes in circulating endotoxin levels of anti-LPS IgG activity following the race. 4. From these results, we conclude that the mild, transient endotoxaemia detected in some of our subjects does not play a major role in the observed inflammatory response to a marathon competition.

Screening and characterization of specific anti-lipopolysaccharide antibodies in Belgian blood donors by enzyme-linked immunosorbent assays.

The goal of this project was to find and collect high concentrations of endotoxin-specific antibodies for therapeutic IgG- or IgM-enriched preparations. Various enzyme-linked immunosorbent assays (ELISAs) were developed to perform longitudinal studies of the serological response to a large panel of smooth and rough purified lipopolysaccharide (LPS) extracts in a population of healthy blood donors. To accomplish this, 1612 human serum samples from volunteer blood donors collected by seven different blood banks in Belgium were screened and specific IgM and IgG activities were measured. Approximately 17% of the donors had anti-LPS concentrations higher than 40 mg L-1. Of these, 10.9% had anti-smooth LPS antibodies, 3.7% had anti-rough LPS antibodies and 2.8% were found to be positive towards both types of LPS. The mean anti-LPS antibody concentration was 8 mg L-1 for rough LPS and 14 mg L-1 for smooth LPS. Age- and sex-related distributions of the activities indicated that the greatest prevalence of high anti-LPS concentration was in women aged 40-49 years and in men older than 60 years. Differential absorption experiments showed that the pooled serum of selected blood donors contained a mixture of specific and cross-reacting antibodies. We detected predominantly anti-LPS activities due to the IgG1 and IgG2 subclasses. The range of specificities to different LPS was increased by the pooling of selected sera. It was concluded that pools of naturally occurring specific anti-LPS immunoglobulin antibodies may be obtained in Belgium by screening blood donors using ELISAs that we have developed.

The effect of periodontal parameters on the subgingival microbiota around implants.

The study aimed to examine the relationship between the subgingival flora around implants and their periodontal parameters. Plaque samples from 561 implants (279 patients) were analyzed by means of differential phase contrast microscopy and compared with the sample site's probing depth, bleeding tendency on probing, and plaque and gingivitis indices. If possible, one implant with deep and one with shallow pockets were selected within the same patient. The impact of the intraoral exposure time on the microbial composition around the implants was examined cross-sectionally, with the same group of patients. Only tendencies can be detected by the latter, and no concrete conclusions can be drawn. From the clinical parameters, increased probing depth was found to detrimentally increase the proportion of spirochetes and motile organisms, whereas the other parameters were found to be of minor importance. For partially edentulous patients only, there was a tendency for increased proportions of spirochetes and motile organisms the longer the intraoral exposure time. These observations emphasize the importance of the periodontal health of the remaining teeth (as a reservoir of pathogenic microorganisms) in partial edentulous patients rehabilitated by means of implants and indicate the importance of shallow pockets around implants (flap trimming when aesthetics and phonetics allow).

The influence of splinting procedures on the periodontal and peri-implant tissue damping characteristics. A longitudinal study with the Periotest device.

The aim of the present study was to evaluate the capability of the Periotest device in detecting and monitoring functional changes in the periodontal as well as in the pari-implant damping characteristics. In the first part of this study, 107 teeth were splinted by means of 40 full acrylic fixed prostheses (AFP) and another 37 teeth were splinted by means of 14 ceramometallic fixed prostheses (C-MFP). The Periotest measurements of individual teeth were done the day the fixed prostheses were cemented temporary (PTV 1), and again after a mean observation period of 27.4 days (PTV 2). In the 2nd part, 78 osseointegrated two-stage implants were splinted by means of 23 full acrylic fixed prosthesis (AFP) and other 18 implants were left without it. Using the same abutment length, Periotest measurements were performed, at abutment connections and before installation of the final prosthesis. In a 3rd part, using both implants and teeth as abutments, 29 osseointegrated implants were connected with 25 abutment teeth by means of 7 AFP. The measurements were performed at the beginning of the prosthetic treatment and 2, 4 and 6 weeks later. After splinting teeth by means of AFP for the observation period, no statistically significant reduction in PTVs was found. When on the other hand, a C-MFP was used, PTV 2 showed a significant reduction. The PTVs at abutment connection went down after a period of time, during which some implants were interconnected by means of an AFP and others were not.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of periodontal tissues damping characteristics: current concepts and clinical trials.

The reproducibility of an electronic device for the assessment of periodontal tissues damping characteristics was judged by evaluating the inter-examiner, inter-device and day to day variations of the measurements (PTVs). Nine young periodontally healthy volunteers were examined by two examiners (EX-1 and EX-2) and two devices (D-1 and D-2) in the following sequence: EX-1 D-1, EX-2 D-1, EX-1 D-2, and EX-2 D-2. PTVs were obtained at 5 different occasions during the same day. In some instances examiner 2 measured higher scores than examiner 1 with both devices. This difference was statistically significant (P = 0.05), if the total of 900 measurements was considered. The measurements of device 2 were approximately 0.5 PTV units higher, also reaching a statistical significance (P = 0.05). This difference is of limited clinical significance. The day to day variation was evaluated by comparing the scores obtained at 8 a.m. with the ones at the four other periods. The lowest scores were measured at 8 a.m. Only the 11 a.m. and the 2 p.m. measurements differed significantly. The effect of hormonal changes during the menstrual cycle and of smoking habits on PTVs were also evaluated. Ten female periodontally healthy volunteers were examined three times a week, during a period of two menstrual cycles. No significant PTV changes were found during the menstrual cycle. The effect of the smoking habit on PTVs was tested on 23 periodontally healthy patients.(ABSTRACT TRUNCATED AT 250 WORDS)