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The IUPS Physiome and the European Commission’s Virtual Physiological Human (VPH), funded under the Framework 7 programme, are just two of the major initiatives that have supported the development of physiological models for clinical decision support. There is significantprogress in the formalisation of the concept of the Digital Twin for human physiology and in processes for model personalisation, verification and validation. The VPH Institute and the Avicenna Alliance continue to promote best practice in this area. One of the most important challenges is to achieve the right level of complexity in the model. The most comprehensive models seek to capture all that is known about the physiological system, including detailed anatomy, organ interactions, control functions, and physical, chemical and biological processes. These models can be of enormous value in understanding human physiology, but can also be terribly difficult to personalise to support the clinical management of an individual. There is inevitable conflict between model complexity and the pragmatic limitation of data collection in the clinical pathway. In this presentation we make the case for a 3-axis digital twin, including recognition of the individual physiological envelope, and introduce three applications in cardiovascular medicine.

Nicotinic acetylcholine (nACh) receptors are pentameric ligand-gated ion channels that mediate fast synaptic transmission. The α4β2 nACh receptor is highly expressed in the brain and exists in two functional stoichiometries: the (α4)

Relationships between freshwater flows and growth rates of the opportunistic predatory finfish barramundi Lates calcarifer in a dry tropical estuary were examined using data from a long-term tag-recapture programme. Lagged effects were not investigated. After accounting for length at release, time at liberty and seasonal variation (e.g. winter, spring, summer and autumn), growth rates were significantly and positively related to fresh water flowing to the estuary. Effects were present at relatively low levels of freshwater flow (i.e. 2.15 m3 s-1, the 5th percentile of the mean flow rate experienced by fish in the study during time at liberty). The analysis, although correlative, provides quantitative evidence to support the hypothesis that freshwater flows are important in driving the productivity of estuaries and can improve growth of species high in the trophic chain.

Background Systemic endotoxaemia is implicated in the development of complications associated with obstructive jaundice. The aims of these studies were to assess the systemic immune response to intervention in patients with jaundice and to compare the effects of surgical and non-surgical biliary drainage on host immune function and gut barrier function. Methods In the first study, 18 jaundiced and 12 control patients were studied to assess systemic immune responses before and after intervention. In the second study, immune responses and gut barrier function were assessed following surgical and non-operative biliary decompression in 45 patients with jaundice. Results Endotoxin antibody concentrations fell significantly in patients with jaundice immediately after surgical intervention, but not after non-operative biliary drainage. This decrease was associated with a significant increase in serum P55 soluble tumour necrosis factor (sTNF) receptor concentration (5·3 versus 10·5 ng/ml; P < 0·001), urinary excretion of P55 TNF receptors (21·4 versus 78·8 ng/ml; P = 0·002) and intestinal permeability (lactulose : mannitol ratio 0·032 versus 0·082; P = 0·048). Intestinal permeability was significantly increased in patients with jaundice compared with controls (0·033 versus 0·015; P = 0·002). Conclusion These data suggest that obstructive jaundice is associated with impaired gut barrier function and activation of host immune function that is exacerbated by intervention. Surgery causes an exaggerated pathophysiological disturbance not seen with non-operative biliary drainage procedures.

BACKGROUND: It is not known whether variant CJD can be transmitted within the human population by blood transfusion. The expression of normal cellular prion protein (PrPC) by different blood cell types may permit selective uptake and dissemination of infectivity. STUDY DESIGN AND METHODS: The normal distribution of PrPC on the major blood cell types of species known to be susceptible to natural or experimental transmissible spongiform encephalopathies was studied. Blood from healthy humans, mice, hamsters, cattle, and sheep was examined by flow cytometry by using a large panel of antibodies with different prion protein (PrP) epitope specificities to maximize the detection of PrP variants across species and cell type. RESULTS: PrP was detected on all major human blood cells types except eosinophils, but was not detected as ubiquitously or uniformly on major blood cell types of different animal species. CONCLUSION: Different animal species have unique patterns of expression of PrPC on blood cell types, with none equivalent to the human pattern. This needs to be considered when extrapolating from animal models of blood-borne transmissible spongiform encephalopathy infectivity, particularly in regard to the risk assessment of potential variant CJD spread within the human population. The relationship between PrP distribution and infectivity distribution in blood needs further investigation.

Background Complex limb trauma often involves combined arterial and venous injury, and the resultant ischaemia–reperfusion injury (IRI) causes both local and remote organ injury. This study assessed the influence of the timing of restoration of venous drainage on IRI. Methods Male New Zealand white rabbits (n = 36) were randomized into six groups: sham operation (group 1) and unilateral hind limb arterial and venous occlusion for 1 h followed by no reflow for 2 h (group 2), arterial and venous reflow for 2 h (group 3), arterial reflow alone for 2 h (group 4), arterial reflow alone for 1 h followed by arterial and venous (delayed) reflow for a further 1 h (group 5), and pretreatment with an enteral combination antioxidant before occlusion of both artery and vein and delayed venous reflow (group 6). Plasma hydroperoxide (HPO) and glutathione peroxidase concentration, hind limb skeletal muscle and lung tissue wet: dry weight ratios and myeloperoxidase (MPO) concentration were measured. Results The plasma HPO level in the femoral vein effluent was significantly greater after delayed venous reflow (mean(s.e.m.) 2·02(0·54) μmol/l) than in control animals (0·98(0·10) μmol/l) (P < 0·05). There was also a significantly greater tissue wet: dry weight ratio after delayed venous reflow than in controls, in skeletal muscle (mean(s.e.m.) 6·89(0·14) versus 5·34(0·54); P < 0·05) and lung (9·20(1·14) versus 7·23(0·38); P < 0·05) tissue. Lung tissue MPO activity was significantly greater after delayed venous reflow compared with controls (3·20(0·28) versus 1·86(0·14) units/g; P < 0·005), and also in comparison to simultaneous arterial and venous reflow (2·40(0·24) units/g; P < 0·05). In the antioxidant pretreatment group there was no significant increase in plasma HPO concentration, tissue MPO level or tissue wet: dry weight ratio compared with the control group. Conclusion In combined major arterial and venous injury of the limb, delayed restoration of venous drainage leads to significantly greater local skeletal muscle injury and remote neutrophil-mediated lung injury. These results support the clinical rationale for early restoration not only of arterial inflow but also venous drainage by means of intraluminal shunts.

Objectives to investigate the effect of intestinal manipulation on intestinal permeability and endotoxaemia during elective abdominal aortic aneurysm (AAA) surgery. Design prospective randomised controlled study.Patients and methods fourteen patients undergoing elective infrarenal AAA repair were randomised into either the transperitoneal (n=7) or extraperitoneal approach (n=7). Intestinal permeability was measured preoperatively (PO), and at day 1 (D1) and day 3 (D3) after surgery using the lactulose/mannitol absorption test. Portal and systemic blood samples were taken before clamping, at completion of proximal and distal anastomoses and immediately before abdominal wound closure, for endotoxin measurement using the chromogenic limulus amoebocyte lysate assay. Results intestinal permeability was significantly increased at D1 (0.107±0.04 (mean±S.E.M.)) in the transperitoneal group compared to the PO level (0.020±0.004, p

Background Gram-negative sepsis and its sequelae frequently complicate invasive procedures in patients with obstructive jaundice. In response to endotoxin, Kupffer cells secrete tumour necrosis factor (TNF), a pivotal early mediator of sepsis. An investigation was carried out into the specific role of Kupffer cell TNF secretion following endotoxin challenge in obstructive jaundice. Methods Survival following intraperitoneal administration of endotoxin (2·0, 0·02 and 0·0002 mg per 100 g) was determined in rats following bile duct ligation (BDL) or sham operation. Plasma TNF concentration was quantified following endotoxin administration (0·0002 mg per 100 g) at 1, 2 and 6 h. Subsequently, the effect of Kupffer cell blockade by gadolinium chloride on survival and plasma TNF concentration was assessed. Results Jaundiced animals showed a significantly increased mortality rate following intraperitoneal injection of endotoxin 2·0 mg per 100 g (BDL 100 per cent versus sham 0 per cent) and 0·02 mg per 100 g (BDL 70 per cent versus sham 0 per cent; P = 0·002, Fisher's exact test). Median plasma TNF concentration was significantly greater in jaundiced animals 1 h after endotoxin administration (BDL 943 (interquartile range (i.q.r.) 211–3900) pg/ml versus sham 64 (i.q.r. 47–127) pg/ml; P = 0·002, Mann–Whitney U test). Kupffer cell blockade with gadolinium chloride increased the survival rate following endotoxin administration in BDL animals (BDL-GdCl3 100 per cent versus BDL-saline 40 per cent; P = 0·0003, Fisher's exact test) and decreased median plasma levels of TNF (BDL-GdCl3 88 (i.q.r. 0–1065) pg/ml versus BDL-saline 16 550 (1255–29 360) pg/ml; P = 0·002, Mann–Whitney U test). Conclusion Kupffer cell blockade improved survival and suppressed systemic TNF activity after endotoxin challenge. In obstructive jaundice, hypersecretion of TNF by Kupffer cells may supplement systemic cytokine production and be responsible for significant complications.

Background Sepsis and endotoxaemia occur frequently in biliary obstruction. Impaired Kupffer cell endocytosis is implicated in these events. Tumour necrosis factor and interleukin 6, secreted by Kupffer cells, are important mediators of sepsis. Kupffer cell clearance of endotoxin and secretion of cytokines in experimental obstructive jaundice were investigated. Methods Wistar rats were randomized to bile duct ligation, sham operation or control. Groups (n = 8) were studied 1 and 3 weeks after operation. Kupffer cell function was assessed using in situ hepatic perfusion. Results Clearance of endotoxin was significantly depressed 1 week (median (interquartile range) 20·3 (10·5–27·1) per cent) and 3 weeks (22·1 (20·2–23·2) per cent) after bile duct ligation compared with that in respective sham animals (35·5 (29·9–41·6) and 40·9 (37·7–47·0) per cent) and controls (39·5 (37·3–46·8) per cent). Secretion of tumour necrosis factor was significantly greater 1 week (1113·7 (706·5–1436·8) pg/ml) and 3 weeks (1118·2 (775·7–1484·1) pg/ml) following bile duct ligation compared with that in respective sham animals (114·3 (0–178·5) and 107·6 (63·7–166·4) pg/ml) and controls (0 (0–20·7) pg/ml). Interleukin 6 was not secreted by sham or control animals but was present in the perfusate from jaundiced animals at 1 and 3 weeks (52·5 (9·9–89·5) and 66·2 (60·2–193·1) pg/ml). Conclusion These data demonstrate simultaneous impairment of Kupffer cell clearance of endotoxin and increased secretion of proinflammatory cytokines in experimental obstructive jaundice. These diverse responses may contribute to the development of sepsis-related complications in biliary obstruction.

Background The endotoxin–proinflammatory cytokine cascade has been implicated in the systemic complications of severe acute pancreatitis. Although systemic proinflammatory cytokine activation has been demonstrated in experimental models, the initiating event may be pancreatic inflammation and not systemic endotoxaemia. The aim of this study was to characterise the systemic tumour necrosis factor (TNF) and interleukin-6 (IL-6) response in the taurocholate model of severe acute pancreatitis and to evaluate the role of endotoxaemia, by measuring endotoxin and antiendotoxin antibodies in the systemic compartment. Methods Acute pancreatitis was induced by the retrograde infusion of 0.2 ml 5% sodium taurocholate into the pancreas of male Wistar rats. Saline infusion was used in control rats. Animals were randomised to have venous blood sampling at 1, 2, 4, 6 or 12 h after pancreatic infusion. Blood samples were assayed for endotoxin [limulus amoebocyte lysate (LAL) assay], immunoglobulin(lg)G and IgM antiendotoxin antibodies (ELISA), TNF (WEHI bioassay and ELISA) and IL-6 (B9 bioassay). Results Plasma endotoxin was not detected and there was no difference in IgG and IgM antiendotoxin antibody concentration between pancreatitis animals and controls. At 1 and 2 h, systemic TNF was detected in rats with pancreatitis using both bioassay and ELISA, but not in controls ( p p p Conclusion Systemic proinflammatory cytokine activation occurs in the taurocholate model of severe acute panceatitis. TNF activation is biphasic, occurring at 1 and 2 h following induction of pancreatitis and again at 12 h, while systemic IL-6 concentration increased throughout the period of study. These cytokine responses may be independent of systemic endotoxaemia, since endotoxin was not detected in the systemic compartment and there was no change in the concentration of antiendotoxin antibodies.

[Structure: see text] N,N-Bis(ethoxymethyl)alkylamines function as effective reagents in the double-Mannich annulation of cyclic ketone substrates, providing efficient access to a series of azabicyclic ketones. These ring systems are a useful scaffold for the four-step synthesis of novel constrained homocholine analogues.

Background It has been suggested that bowel permeability is altered following abdominal aortic aneurysm surgery. The effect of ischaemia-reperfusion injury to the lower limb on the morphological structure, neutrophil infiltration and permeability of the bowel was investigated. Methods Histological assessment of the bowel was undertaken in five groups of Wistar rats: control, 3 h of bilateral hind limb ischaemia and 3 h of bilateral hind limb ischaemia followed by 1, 2 or 3 h of reperfusion. Using an everted gut sac model and 14 C-labelled polyethylene glycol, the effect of ischaemia-reperfusion on small bowel permeability was studied. Results The small bowel showed a significant decrease in mucosal thickness, villus height and crypt depth in animals subjected to ischaemia followed by 2-hr reperfusion (mean(s.e.m.) 420(15), 217(9) and 163(6) μm respectively) compared with controls (481(11), 245(6) and 195(6) μm) (P

Objectives To assess the specific host responses to systemic endotoxemia and tumor necrosis factor (TNF) activation after abdominal aortic aneurysm surgery by measuring antiendotoxin core antibodies (EndoCab) immunoglobulin (Ig)G and IgM, and soluble p55TNF receptor concentrations. The role of the gut in initiating these immune responses was evaluated by correlating the systemic markers to changes in the intramucosal pH of the sigmoid colon. Design Retrospective, reevaluation study. Setting Vascular unit of a university hospital. Patients Eleven patients who underwent abdominal aortic aneurysm repair surgery were selected from a larger patient cohort (n = 42) on the basis of their clinical outcome (four patients had fatal complications and seven patients had an uneventful recovery). Interventions After induction of anesthesia, intramucosal pH of the sigmoid colon was measured using tonometry. Blood samples were obtained from indwelling catheters or direct venipuncture preoperatively, during surgery, and daily until postoperative day 5. Measurements and Main Results Those patients who died developed intramucosal acidosis of the sigmoid colon intraoperatively. Significant consumption of both IgG and IgM EndoCab antibodies was found in all patients. By measuring the concentration of antibodies to a neutral antigen, i.e., tetanus toxoid, the consumption of IgG EndoCab antibody concentrations was shown to be a specific host response. In all patients, reciprocal changes in the serum concentrations of p55TNF receptor and interleukin (IL)-6 were observed. The percentage increase in p55TNF receptor and the concentration of IL-6 were significantly higher in the nonsurvivor group by 48 hrs. There were significant correlations between, intramucosal pH and EndoCab antibodies, intramucosal pH and p55 TNF receptor, and p55 TNF receptor and IL-6. Conclusions The development of colonic ischemia is associated with a significant consumption of IgG EndoCab antibodies and a simultaneous increase in soluble p55TNF receptor. This study provides further support for the concept that gut-derived endotoxin and the generation of TNF may play a role in the pathogenesis of complications after abdominal aortic aneurysm surgery. (Crit Care Med 1997; 25:1472-1479)

Background Tumour necrosis factor (TNF) is a pleiotropic cytokine produced largely by macrophages and T lymphocytes. It has been implicated in the pathogenesis of numerous immunoinflammatory processes. Recently, a number of studies have indicated that anti-TNF antibodies may be of value in the treatment of inflammatory bowel disease. Method The literature is reviewed regarding the role of TNF in the pathogenesis of inflammatory bowel disease and the results of administering TNF inhibitors. Results and conclusions TNF may have a role in the pathogenesis of inflammatory bowel disease. The effects of TNF inhibitors are complex and incompletely understood. Anti-TNF antibody strategies may have a role in the treatment of acute exacerbations of the disease but are unlikely to be appropriate therapies for long-term management.

Restoration of blood flow to an acutely ischemic lower limb may paradoxically result in systemic complications and unexpected mortality. It has been suggested that lower limb ischemia reperfusion alters gut permeability. In this study, using a rat model, we determined the effect of acute lower limb ischemia-reperfusion on mortality rate, bowel morphology, and circulating concentrations of endotoxin and the proinflammatory cytokine interleukin-6. Survival rate was compared in two groups of adult Wistar rats: (1) control group (n = 10); and (2) animals subjected to 3 hours of bilateral hind limb ischemia followed by reperfusion (n = 10). Both groups were observed under standard conditions for 4 days. In a second experiment three groups of animals were studied: (I) control (n = 12); (II) 3 hours of bilateral hind limb ischemia alone (n = 12); and (III) 3 hours of bilateral hind limb ischemia followed by 2 hours of reperfusion (n = 12). Animals subjected to bilateral hind limb ischemia followed by reperfusion had a significantly higher mortality rate (70%) than controls (0%) (p0.005). Morphometric assessment of the small bowel showed a significant decrease in mean mucosal thickness in the ischemia-reperfusion group compared with that in the group of controls and the ischemia-alone group (p0.05). Bilateral hind limb ischemia followed by reperfusion was associated with significantly increased plasma concentrations of endotoxin (p0. 05) and interleukin-6 (p0.0001) compared with that of controls and ischemia alone. These results indicate that reperfusion of the acutely ischemic lower limb is accompanied by structural changes in the gut mucosa associated with increased systemic endotoxin concentrations and cytokine activation. Mortality following reperfusion of the acutely ischemic limb may be related to a systemic inflammatory response triggered by endotoxin of gut origin.

BACKGROUND: Gram negative septic events are the commonest source of morbidity and mortality as a result of surgery in jaundiced patients. The large intestine provides the major source of Gram negative bacteria in mammals and is implicated in the pathogenesis of systemic endotoxaemia in obstructive jaundice. Bile salts have an important part in maintaining indigenous microecological homeostasis through their emulsifying properties. AIMS: The aim was to investigate the effects of biliary obstruction and isolated external biliary diversion on gastro-intestinal structure and caecal bacterial flora in relation to bacterial translocation. METHOD: Six groups of adult male Wistar rats were studied (no operation, sham operated, and bile duct ligated (BDL) for one and three weeks and a choledocho-vesical fistula (CDVF) for one week). At the end of the study period plasma was assayed for evidence of endotoxaemia and the animals were tested for bacterial translocation to the mesenteric lymph node complex (MLNC), liver, lungs, and spleen. Quantitative and qualitative bacteriological studies were performed on the caecal contents and segments of colon and terminal ileum were washed and prepared for histological assessment. RESULTS: Bacterial translocation was significantly increased in the BDL1 (68.8%) and BDL3 (60%) groups compared with the sham1 (6.3%), sham3 (9.1%), No operation (0%), and CDVF1 (16.7%) groups. Although translocation was more pronounced in the BDL1 group, this was almost exclusively to the MLNC compared with the more widespread translocation to other organs in the BDL3 group. The BDL3 group was the only group with significantly raised concentrations of endotoxin and anticore glycolipid. The caecal Gram negative aerobic counts were significantly increased in the BDL1 and CDVF1 groups compared with all other groups. There was evidence of structural abnormalities in the terminal ileum of rats jaundiced for three weeks, but not in the other groups. CONCLUSIONS: Biliary obstruction for one and three weeks promotes bacterial translocation although the mechanisms may be different. Absence of intralumenal bile results in a significant but self limiting increase in the Gram negative aerobic population, which may account for translocation in the early stages of biliary obstruction. As the duration of biliary obstruction increases systemic endotoxaemia is a consistent feature which, combined with factors such as immunological depression and physical disruption of gut barrier function, may promote bacterial translocation perpetuating systemic sepsis.

National and international geographic variations in the incidence and mortality rates of colorectal cancer along with changes in prevalence among migrant populations would suggest that environmental factors have a role in the aetiology of this disease. Animal models of chemically induced colonic carcinogenesis have been widely used to assess the effect of dietary components such as fat and fibre. These studies have shown that the type of fat is important. Polyunsaturated vegetable oils rich in ω-6 fatty acids have a promotional role whereas fish oil rich in ω-3 fatty acids has no promotional effect and may even inhibit tumour formation. Studies of the effect of fibres have shown that insoluble dietary fibres such as wheat bran and cellulose may have a protective role. However, soluble fibres such as pectin and psyllium offer little protection and in fact carrageenan may have a promotional effect. It has been suggested that phytic acid (inosital hexaphosphate), a component of many fibre-rich diets, rather than fibre per se, has a role in the suppression of colonic carcinogenesis. Despite conflicting evidence, it may be plausible to advocate a high fibre, low fat diet as a measure of secondary prevention of colorectal cancer.

The effect of low-dose dopamine administration on intramucosal pH (pHi) of the sigmoid colon and on postoperative function of various organs in patients undergoing elective abdominal aortic aneurysm repair was examined. Nineteen patients were randomized to two groups; nine received dopamine at a rate of 3 μg per kg per min for 24 h from induction of anaesthesia and ten control patients received fluids without dopamine. pHi was measured with a silicone tonometer and daily samples of blood were taken for measurement of liver transaminase activity, arterial oxygen saturation and creatinine concentration. Mean(s.e.m.) pHi fell to a significantly lower minimum value in those receiving dopamine compared with control patients (6.86(0.10) versus 7.11(0.08), P

Quantitative and qualitative disturbances in faecal flora suggest a role for enteric bacteria and their products in the pathogenesis of inflammatory bowel disease (IBD). This study investigated the hypothesis that systemically circulating endotoxins are of pathogenic significance in IBD by measuring antibody, cytokine, and acute phase protein responses. Systemic endotoxaemia was found in 88% patients with ulcerative colitis (n = 25) and 94% with Crohn's disease (n = 31) during clinical relapse. Systemic endotoxaemia correlated positively with anatomic extent and clinical activity of ulcerative colitis. Circulating tumour necrosis factor (TNF) was detected in 40% of patients with ulcerative colitis and 45% with Crohn's disease. Plasma TNF concentrations correlated with clinical and laboratory measures of disease activity and were associated with a surgical outcome to the disease episode. Plasma soluble TNF receptor p55 concentration correlated positively with disease activity and endotoxin core antibody concentrations. Plasma IgG endotoxin core antibody concentrations were significantly increased in patients with Crohn's disease and correlated with systemic endotoxaemia. The presence of systemic endotoxaemia, its correlation with disease activity, disease extent, and endotoxin core antibody concentration and the detection of circulating TNF and soluble TNF receptors all support a pathogenic role for endotoxins in IBD.

1. Infection in the neonatal period is difficult to diagnose and is a significant cause of morbidity and mortality in preterm infants. 2. We investigated prospectively the predictive value of plasma measurement of bacterial endotoxin (lipo-polysaccharide), tumour necrosis factor-α, interleukin-6, interleukin-8, intercellular adhesion molecule-1 and C-reactive protein in 60 consecutive newborn infants suspected of having neonatal infection. Plasma samples were taken at the time of acute clinical deterioration. Sixty-two cord blood samples were studied as controls taken at elective Caesarean section. 3. Forty-three infants had confirmed infections, 25 with positive blood cultures. Tumour necrosis factor-α and bacterial endotoxin levels were not significantly elevated over controls, whereas interleukin-6, interleukin-8 and intercellular adhesion molecule-1 levels were all significantly increased in the infected group compared with controls (all P < 0.001). 4. Increased plasma intercellular adhesion molecule-1 levels were a highly sensitive (88%) indicator of clinical infection and were independent of C-reactive protein. Use of these two assays in combination improved the diagnostic sensitivity to 95% and gave a negative predictive value of 97%. Addition of interleukin-6 or interleukin-8 measurements failed to further significantly enhance the prediction of infection. 5. Measurement of intercellular adhesion molecule-1 level may have a clinical role in rapidly confirming, or predicting, the likely diagnosis in cases of suspected neonatal infection.

In 30 patients undergoing elective repair of abdominal aortic aneurysm the intramucosal pH (pHi) of the sigmoid colon was measured. Blood for endotoxin assay was taken at intervals before, during and after surgery. Daily measurements were made of liver transaminase activity and of arterial partial pressure of oxygen (PaO2). The mean(s.e.m.) peak systemic endotoxin concentration in those who developed intramucosal acidosis (pHi below 7·00) was 90(14) pg/ml, compared with 42(5) pg/ml in those who did not (P < 0·01). In the 14 patients whose pHi fell below 7·00, the mean(s.e.m.) postoperative rise in aspartate transaminase activity was 346(74) per cent, compared with 181(20) per cent in those whose pHi remained above this level (P < 0·05). The mean(s.e.m.) postoperative ratio of PaO2, to the fraction of inspired oxygen was 177(11) mmHg in those with intramucosal acidosis, compared with 260(24) mmHg in those whose pHi remained above 7·00 (P < 0·01). These results demonstrate a relationship between bowel ischaemia, endotoxaemia and organ impairment following elective aneurysm repair.

Macrophage major histocompatibility complex (MHC) class II antigen expression is associated with defective antigen presentation to T lymphocytes in animals and is predictive of patient outcome after major trauma or sepsis. In this study, class II antigen (HLA-DR and DQ) expression on peripheral blood monocytes was investigated in patients with inflammatory bowel disease in relation to disease activity and outcome. The percentage positivity and fluorescent intensity of expression of HLA-DR and DQ antigens on monocytes were determined in whole blood samples using dual colour immunofluorescence labelling and flow cytometry. Disease activity was assessed using clinical and laboratory indices. There was no significant difference in percentage positivity or fluorescent intensity of class II antigen expression between patients with Crohn's disease, those with ulcerative colitis, and healthy volunteers. The percentage of monocytes displaying HLA-DR positivity was significantly decreased in patients with active ulcerative colitis (active %: 49.5 (5.6); inactive %: 78.9 (6.9); p = 0.01). Data expressed as mean (SEM). In patients requiring surgical resection of diseased bowel, the percentage of monocytes displaying HLA-DR positivity (51.9 (4.0) %) was significantly reduced compared with patients receiving medical treatment alone (81.1 (3.5) %; p < 0.001). Reduced monocyte HLA-DR expression is therefore associated with disease activity and seems to predict outcome in patients with inflammatory bowel disease.

In a cohort of victims of traumatic brain injury, 18 out of 50 patients had a plasma tumour necrosis factor (TNF) concentration above 2 pg/ml within 24 h of injury (mean 12.19, SD 45.96 pg/ml). Twenty-six had CSF samples available of which 17 demonstrated TNF concentrations above 1 pg/ml (mean 3.98, SD 3.61 pg/ml). We conclude that traumatized brain parenchyma is a significant source of TNF activity and implicate the cytokine in cellular metabolic derangements following head injury.

Neuronal nicotinic acetylcholine receptors (nAChR) are ligand gated ion channels that mediate fast synaptic transmission. Methyllycaconitine (MLA) is a selective and potent antagonist of the α7 nAChR, and its anthranilate ester side-chain is important for its activity. Here we report the influence of structure on nAChR inhibition for a series of novel MLA analogs, incorporating either an alcohol or anthranilate ester side-chain to an azabicyclic or azatricyclic core against rat α7, α4β2, and α3β4 nAChRs expressed in Xenopus oocytes. The analogs inhibited ACh (EC(50)) within an IC(50) range of 2.3-26.6 μM. Most displayed noncompetitive antagonism, but the anthranilate ester analogs exerted competitive behavior at the α7 nAChR. At α4β2 nAChRs, inhibition by the azabicyclic alcohol was voltage-dependent suggesting channel block. The channel-lining residues of α4 subunits were mutated to cysteine and the effect of azabicyclic alcohol was evaluated by competition with methanethiosulfonate ethylammonium (MTSEA) and a thiol-reactive probe in the open, closed, and desensitized states of α4β2 nAChRs. The azabicyclic alcohol was found to compete with MTSEA between residues 6' and 13' in a state-dependent manner, but the reactive probe only bonded with 13' in the open state. The data suggest that the 13' position is the dominant binding site. Ligand docking of the azabicyclic alcohol into a (α4)(3)(β2)(2) homology model of the closed channel showed that the ligand can be accommodated at this location. Thus our data reveal distinct pharmacological differences between different nAChR subtypes and also identify a specific binding site for a noncompetitive channel blocker.

In this study we report on the synthesis, kinetic characterization and application of a novel biotinylated and active-site-directed inactivator of cathepsin B. Thus the peptidyldiazomethane biotinyl-Phe-Ala-diazomethane has been synthesized by a combination of solid-phase and solution methodologies and has been shown to be a very efficient inactivator of bovine and human cathepsin B. The respective apparent second-order rate constants (k0bs./[I]) for the inactivation of the human and bovine enzymes by this reagent, namely approximately 5.4 x 10(4) M-1.min-1 and approximately 7.8 x 10(4) M-1.min-1, compare very favourably with those values determined for the urethane-protected analogue benzyloxycarbonyl-Phe-Ala-chloromethane first described by Green & Shaw [(1981) J. Biol. Chem. 256, 1923-1928], thus demonstrating that the presence of the biotin moiety at the P3 position is compatible with inhibitor effectiveness. The utilization of this reagent for the detection of cathepsin B in electrophoretic gels, using Western blotting and in combination with a streptavidin/alkaline phosphatase detection system, is also demonstrated. Given that the peptidyldiazomethanes exhibit a pronounced reactivity towards cysteine proteinases, we feel that the present label may well constitute the archetypal example of a wide range of reagents for the selective labelling of this class of proteinase, even in a complex biological milieu containing additional classes of proteinases.

Analyzing communication data within a social structure represented by a wholesale agricultural market demonstrates the utility of network analysis techniques for identifying systems. A representation of these data in matrix form permits exploration of the stability properties of the system. The stability analyses lend some support for theoretical arguments pertaining to the conditions leading to system equilibrium.

This study compared mortality rates, endotoxaemia, systemic tumour necrosis factor (TNF) and interleukin (IL)-6 concentrations after continuous and intermittent hepatic ischaemia. Two groups of rats were subjected to continuous or intermittent left hepatic inflow occlusion for a total period of 120 min in each group. Intermittent ischaemia was associated with significantly lower mortality rates than continuous ischaemia (four of 20 versus 15 of 20; P = 0±0015). In a separate study, again following 120 min continuous or intermittent ischaemia, systemic blood was sampled at 0 min, 1 h, 3 h and 5 h after final clamp release for measurement of endotoxin, TNF and IL-6 concentrations. Endotoxin concentrations were significantly lower at 1 h, as were TNF and IL-6 concentrations at 3 and 5 h, after final clamp release in the group having intermittent ischaemia (P

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 per cent 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) per cent 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) per cent, P < 0·05). In this animal model of obstructive jaundice dietary supplementation with L-arginine diminished both weight loss and immune suppression.

Intestinal mucosal barrier dysfunction observed in patients undergoing transperitoneal abdominal aortic aneurysm (AAA) repair may contribute to the development of the systemic inflammatory response syndrome and dysfunction of various organs. The aim of this study is to investigate whether an extraperitoneal approach reduces intestinal mucosal barrier and renal dysfunction in elective infrarenal AAA repair.Twenty patients admitted for elective infrarenal AAA repair were randomized into either the transperitoneal approach (n=10) or the extraperitoneal approach (n=10). Intestinal permeability was measured preoperatively, and at day 1 and day 3 after surgery using the lactulose/mannitol test by calculating the differential urinary excretion ratio of the two sugars after oral administration. Renal dysfunction was assessed by measuring the urinary albumin/creatinine ratio (ACR) at the same time points.Intestinal permeability was significantly increased in the transperitoneal group at day 1 [0.124+/-0.035 (mean+/-s.e.m.)] compared to the preoperative level (0.020+/-0.003), (p=0.001) and to the extraperitoneal group at day 1 (0.025+/-0.008), (p0.05) which showed no change in comparison with the preoperative level (0.020+/-0.003). The ACR was also significantly increased in the transperitoneal group at day 1 (16.69+/-5.12) compared to the preoperative level (5.71+/-2.89), (p0.05) and to the extraperitoneal group at day 1 (4.33+/-1.49), (p0.05) which showed no significant change at any of the times examined. No correlation was observed between the lactulose/mannitol ratio and the albumin/creatinine ratio, or between age, operating time, aortic clamping time, amount of blood lost or blood transfused.These results support the suggestion that minimising intestinal manipulation using an extraperitoneal approach in AAA repair preserves intestinal mucosal barrier and renal glomerular functions.

Systemic endotoxaemia contributes to the high morbidity and mortality of jaundiced patiens undergoing surgery. In this study, correlations between systemic endotoxaemia (assessed by measuring antibodies to the core-glycolipid region of endotoxin, a-CGL), bile acids and blood histamine were investigated in a bile duct ligation (BDL) animal model of obstructive jaundice. Three weeks after BDL, systemic a-CGL (p