Biomedical subjects
G R Barclay
Publications and source records attributed to G R Barclay.
Endogenous endotoxin-core antibody (EndoCAb) as a marker of endotoxin exposure and a prognostic indicator: a review.
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Haemolytic-uraemic syndrome.
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Modulation of immune function and weight loss by L-arginine in obstructive jaundice in the rat.
Jaundiced surgical patients have a high incidence of postoperative complications. Many causative factors have been identified including cachexia and immune suppression. The amino acid L-arginine has anabolic and immunostimulatory properties. It was hypothesized that dietary supplementation with L-arginine would diminish the weight loss and immune suppression of obstructive jaundice. Sixteen male Wistar rats rendered jaundiced by bile duct ligation were allocated to two groups. The test group (n = 8) received drinking water supplemented with 1.8 percent L-arginine ad libitum and the control group (n = 8) received a solution of isonitrogenous glycine. Both groups had free access to standard chow. Body-weight, and fluid and food intake were recorded. After 21 days, delayed-type hypersensitivity to 2,4-dinitrofluorobenzene was assessed. Animals receiving L-arginine consumed more food than controls (mean(s.e.m.) 414(16) versus 360(13) g, P < 0.05) and lost less weight (mean(s.e.m.) proportion of initial body-weight lost 7.8(1.2) versus 14.8(1.4) percent, P < 0.05). The delayed-type hypersensitivity response was significantly greater in rats receiving L-arginine (mean(s.e.m.) increase in ear thickness 23.9(2.7) versus 9.4(2.1) percent, P < 0.05). In this animal model of obstructive jaundice dietary supplementation with L-arginine diminished both weight loss and immune suppression.
Antibodies to endotoxin core in sudden infant death syndrome.
To assess the possible role of endotoxaemia in the pathogenesis of sudden infant death syndrome (SIDS), antibodies to endotoxin core (EndoCAb), which have previously been shown to be depressed by systemic endotoxaemia, were measured. IgG and IgM EndoCAb and total serum IgG and IgM were measured in serum samples from 25 children who had died from SIDS and 164 control children under 1 year of age. Twelve (48%) of the 25 children who had died from SIDS had no detectable IgG EndoCAb compared with 28 (17%) of the 164 control children, and this difference was concentrated in children aged less than 3 months. There was no significant difference between the two groups in the percentage of children with no IgM EndoCAb, nor in the total IgG and IgM concentrations. For IgM EndoCAb, the younger children who had died from SIDS had higher concentrations than the controls. These results suggest that, in children who have died from SIDS, due to either unusually early or severe exposure to endotoxin, maternal IgG EndoCAb have been depleted and early IgM EndoCAb triggered.
Pentoxifylline modulates cytokine responses in a sepsis model.
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Anti-lipopolysaccharide core antibodies.
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Role of serum endotoxin and antiendotoxin core antibody levels in predicting the development of multiple organ failure in acute pancreatitis.
It has been proposed that endotoxin contributes to the development of multiple organ failure (MOF) in acute pancreatitis. Endotoxaemia is transient and may not be detected by intermittent blood sampling. By contrast, not only can changes in the patient's endogenous antiendotoxin core antibody pool persist for many days, but depletion of this pool may be a key event in determining the physiological significance of endotoxaemia. A series of 33 patients with acute pancreatitis had daily measurement of Acute Physiology Score (APS) and levels of C-reactive protein, interleukin 6, endotoxin, immunoglobulin (Ig) G and IgM antiendotoxin core antibodies, and prospective documentation of complications. Endotoxin was detected in the serum of 13 patients, while a significant change in levels of endogenous antiendotoxin core antibodies was detected in all those with severe pancreatitis and in 28 overall. MOF developed in seven patients, five of whom died. The combination of a rising APS over the first 48 h of admission and a significant fall in endogenous IgG antibody level was observed in all patients who developed MOF (seven of seven), but in only one of 16 without MOF (P = 0.00003; overall predictive value 91 per cent). This study suggests that measuring the initial trend in APS and the concentration of endogenous IgG antiendotoxin core antibody provides a means of identifying patients with acute severe pancreatitis who are at high risk of developing MOF. This group might benefit from passive immunotherapy with antiendotoxin antibodies.
Reduction in circulating levels of CD4-positive lymphocytes in acute pancreatitis: relationship to endotoxin, interleukin 6 and disease severity.
The proportion of peripheral blood mononuclear cells expressing the T helper cell phenotype and levels of antiendotoxin core antibody, interleukin (IL) 6 and C-reactive protein (CRP) were determined within 48 h of admission in a group of 29 patients with acute pancreatitis (16 mild, 13 severe attacks). There was a significant decrease in the proportion of T helper cells (12.2 versus 34.9 per cent, P < 0.01) and significant increases in levels of IL-6 (69.5 versus < 10 pg/ml, P < 0.01) and CRP (119 versus 30.5 mg/l, P < 0.01) in severe compared with mild attacks. During the convalescent stage at 3 months after admission, severe attacks were characterized by a significant increase in the proportion of T helper cells compared with the acute period (22.4 versus 10.6 per cent, P < 0.01). A persistently low proportion of T helper cells was associated with residual pancreatic necrosis. The presence of circulating endotoxin was demonstrated in two mild and two severe attacks using the Limulus amoebocyte lysate assay, and abnormal levels of antiendotoxin core antibodies were found in 70 and 92 per cent of mild and severe attacks respectively. There was a strong inverse correlation between levels of CRP and the proportion of T helper cells in severe disease (r = -0.76, P = 0.004). Translocation of endotoxin from the gastrointestinal tract may partly explain the abnormal levels of T helper cells, IL-6 and CRP.
A broadly cross-protective monoclonal antibody binding to Escherichia coli and Salmonella lipopolysaccharides.
During the last decade, episodes of sepsis have increased and Escherichia coli has remained the most frequent clinical isolate. Lipopolysaccharides (LPS; endotoxin) are the major toxic and antigenic components of gram-negative bacteria and qualify as targets for therapeutic interventions. Molecules that neutralize the toxic effects of LPS are actively investigated. In this paper, we describe a murine monoclonal antibody (MAb; WN1 222-5), broadly cross-reactive and cross-protective for smooth (S)-form and rough (R)-form LPS. As shown in enzyme-linked immunosorbent assay and the passive hemolysis assay, WN1 222-5 binds to the five known E. coli core chemotypes, to Salmonella core, and to S-form LPS having these core structures. In immunoblots, it is shown to react with both the nonsubstituted core LPS and with LPS carrying O-side chains, indicating the exposure of the epitope in both S-form and R-form LPS. This MAb of the immunoglobulin G2a class is not lipid A reactive but binds to E. coli J5, an RcP+ mutant which carries an inner core structure common to many members of the family Enterobacteriaceae. Phosphate groups present in the inner core contribute to the epitope but are not essential for the binding of WN1 222-5 to complete core LPS. Cross-reactivity for clinical bacterial isolates is broad. WN1 222-5 binds to all E. coli clinical isolates tested so far (79 blood isolates, 80 urinary isolates, and 21 fecal isolates) and to some Citrobacter, Enterobacter, and Klebsiella isolates. This pattern of reactivity indicates that its binding epitope is widespread among members of the Enterobacteriaceae. WN1 222-5 exhibits biologically relevant activities. In vitro, it inhibits the Limulus amoebocyte lysate assay activity of S-form and R-form LPS in a dose-dependent manner and it neutralizes the LPS-induced release of clinically relevant monokines (interleukin 6 and tumor necrosis factor). In vivo, WN1 222-5 blocks endotoxin-induced pyrogenicity in rabbits and lethality in galactosamine-sensitized mice. The discovery of WN1 222-5 settles the long-lasting controversy over the existence of anti-core LPS MAbs with both cross-reactive and cross-protective activity, opening new possibilities for the immunotherapy of sepsis caused by gram-negative bacteria.
The role of endotoxin immunity, neutrophil degranulation and contact activation in the pathogenesis of post-operative organ dysfunction.
Gut mucosal hypoperfusion is associated with a poor outcome following major surgery but the pathogenetic mechanisms remain poorly understood. We have examined the relationship between gut mucosal hypoperfusion, endotoxin core antibodies (EndoCAb), neutrophil elastase alpha-1 antitrypsin complexes (NE) and components of the contact system during elective major surgery. Of the 26 patients studied 16 developed gut mucosal hypoperfusion (pHi < 7.32) by the end of surgery; of these four developed multiple organ failure (MOF) and three subsequently died. In this group there was a significant rise in NE (P < 0.005) and significant reductions in components of the contact system (factor XII, antithrombin III, prekallikrein and C1-inhibitor; P < 0.001) from immediately before surgery to 24 h later. Ten patients maintained gut mucosal perfusion (pHi > or = 7.32); none of these developed life threatening complications. In this group there was no significant increase in NE and, although there were significant reductions in some components of the contact system (P < 0.01), levels of C1-INH were not reduced. All patients demonstrated a significant reduction in both IgG and IgM EndoCAbs (P < or = 0.005) indicating exposure to endotoxin. However, the group that maintained gut mucosal perfusion had significantly higher IgG EndoCAb levels at baseline and 24 h (P < or = 0.005). These data suggest that all patients were exposed to endotoxin and that high levels of anti-endotoxin antibodies may contribute to the prevention of endotoxin-induced contact activation, neutrophil degranulation and gut mucosal hypoperfusion occurring during major surgery and thus reduce the likelihood of the development of post-operative MOF.
Frequencies of lipopolysaccharide core types among clinical isolates of Escherichia coli defined with monoclonal antibodies.
Mouse monoclonal antibodies (MAbs) specific for the lipopolysaccharide (LPS) core types R1, R2, and R3 of Escherichia coli and a cross-reactive MAb that binds to the LPS core of almost all E. coli were used in ELISA to determine the frequency of cores resembling R1, R2, and R3 in strains of E. coli isolated from clinical samples (blood and urine specimens) and from the feces of asymptomatic individuals. Of the 180 wild-type isolates, 123 were assigned to R1 core type, 14 to R2, and 18 to R3. Twenty-five wild-type E. coli isolates could not be assigned to a particular core type and may have either an R4 or K12 core or a previously unrecognized core type. R1 core type was associated with O types 1, 4, 6, 8, and 18 and with K1 or K5 capsules. R3 was associated with O15. O75 isolates could be of either R1 or R2 core type.
Production and characterisation of mouse monoclonal antibodies reactive with the lipopolysaccharide core of Pseudomonas aeruginosa.
Monoclonal antibodies (MAbs) to the core antigen region of lipopolysaccharide (LPS) of Pseudomonas aeruginosa were produced from mice immunised with whole cells of heat-killed rough mutants of Pseudomonas aeruginosa expressing partial or complete core LPS. MAbs were screened in an enzyme-linked immunosorbent assay (ELISA) against three different antigen cocktails: S-form LPS from three P. aeruginosa strains, R-form LPS from six P. aeruginosa strains and, as a negative control, R-form LPS from Salmonella typhimurium and Escherichia coli. Selected MAbs were subsequently screened against a range of extracted LPS and whole cells from both reference strains and clinical isolates of P. aeruginosa. The antibodies were also screened in ELISA against whole-cell antigens from other Pseudomonas spp. as well as strains of Haemophilus influenzae, Neisseria subflava and Staphylococcus aureus. Five MAbs reacting with the core component of P. aeruginosa LPS were finally selected. Two of these, MAbs 360.7 and 304.1.4, were particularly reactive in immunoblots against unsubstituted core LPS, including that from O-antigenic serotypes of P. aeruginosa. The MAbs also reacted with some of the other Pseudomonas spp., but not with P. cepacia or Xanthomonas (Pseudomonas) maltophilia. Cross-reactivity with whole cells from other bacterial species was minimal or not observed. Reactivity of MAbs with some Staph. aureus strains was observed, and binding to the protein A component was implicated. The reactivity of the MAbs was investigated further by flow cytometry and immunogold electronmicroscopy. The suitability of the MAbs for an immunological assay for detection of P. aeruginosa in respiratory secretions from CF patients is discussed.
The effect of dietary yeast on the activity of stable chronic Crohn's disease.
The effect of dietary yeast on the activity of stable Crohn's disease was assessed in 19 patients. During the 1st month patients continued their usual diet (base-line period), but during the next 2 months dietary yeast was excluded except that during 1 month patients took baker's yeast capsules while for the other month they took placebo capsules. The patients' mean Pettit Crohn's disease activity index (CDAI) while taking baker's yeast (mean, 107.9; SE, 6.1) was significantly greater than during yeast exclusion (mean, 102.1; SE, 5.7; p less than 0.05). The mean of each patient's maximum CDAI during yeast exclusion (mean, 107.1; SE, 5.7) was significantly lower than those during the base-line (mean, 115.2; SE, 6.1; p less than 0.05) and baker's yeast inclusion periods (mean, 113.9; SE, 6.7; p less than 0.05). Patients with elevated yeast antibodies tended to develop a higher CDAI while receiving baker's yeast (13 of 15). These results suggest that dietary yeast may affect the activity of Crohn's disease.
Tissue plasminogen activator in the treatment of superior vena caval thrombosis associated with parenteral nutrition.
Two patients, one of whom was pregnant, developed superior vena caval thrombosis while receiving central parenteral nutrition. They were successfully treated with recombinant tissue plasminogen activator (t-PA).
Changes in anti-endotoxin-IgG antibody and endotoxaemia in three cases of gram-negative septic shock.
Circulating endotoxin levels and IgG antibodies to a range of Gram-negative bacterial lipopolysaccharides (LPS) (endotoxins) of different sizes and structures were measured daily in three cases of septic shock. There was an inverse relationship between endotoxin levels and cross-reactive antibodies to the core glycolipid (CGL) region of lipopolysaccharide. This suggests that antibody to LPS-CGL was initially consumed by a superabundance of endotoxin, and that a resurgence of intrinsic anti-LPS-CGL antibody levels may be associated with a reduction of circulating endotoxin. The implications of these findings for passive antibody therapy of septic shock are discussed.
Effect of cold-induced pain on salt and water transport in the human jejunum.
The possibility that the central and autonomic nervous systems might be involved in the control of intestinal absorption was assessed by measuring the effect of physical stress (cold-induced pain) on jejunal transport in 13 healthy subjects. Using a triple-lumen perfusion technique to determine jejunal absorption, cold pain significantly reduced net water absorption from 34.9 to 15.7 ml/30 cm.50 min (p less than 0.005), net sodium absorption from 2.6 to 0.2 mEq/30 cm.50 min (p less than 0.005), and net chloride absorption from 2.2 to 0.6 mEq/30 cm.50 min (p less than 0.02). These changes were associated with an elevation of blood pressure and plasma norepinephrine during cold pain. During the period following cold pain, systolic blood pressure remained significantly elevated and net jejunal water absorption significantly reduced. These results suggest that physical stress can influence jejunal absorption of salt and water in humans and support the possibility that the central and autonomic nervous systems have a physiologic role in the control of intestinal function.
Effect of moderate exercise on salt and water transport in the human jejunum.
The effect of moderate exercise on jejunal absorption was examined in seven healthy subjects using a triple lumen perfusion technique. Moderate exercise on a bicycle ergometer significantly reduced net absorption of water from 32.0 (4.0) to 16.2 (6.1) ml/30 cm/50 min (p less than 0.02), sodium from 2.4 (0.4) to 0.5 (0.9) mmol/30 cm/50 cm (p less than 0.05), chloride from 2.0 (0.4) to 0.3 (0.7) mmol/30 cm/50 min (p less than 0.05), and potassium from 0.20 (0.02) to 0.01 (0.04) mmol/30 cm/50 min (p less than 0.01). After exercise, water, sodium, and chloride absorption returned towards basal values, but potassium absorption remained significantly decreased. These results suggest that moderate exercise can influence jejunal absorption of salt and water in man. They support the possibility that the autonomic nervous system has a physiological role in the control of intestinal transport, although other mechanisms may be involved.