Efficacy of thiopurines and adalimumab in preventing Crohn's disease recurrence in high-risk patients - a POCER study analysis

BACKGROUND

Crohn's disease recurs in the majority of patients after intestinal resection.

AIM

To compare the relative efficacy of thiopurines and anti-TNF therapy in patients at high risk of disease recurrence.

METHODS

As part of a larger study comparing post-operative management strategies, patients at high risk of recurrence (smoker, perforating disease, ≥2nd operation) were treated after resection of all macroscopic disease with 3 months metronidazole together with either azathioprine 2 mg/kg/day or mercaptopurine 1.5 mg/kg/day. Thiopurine-intolerant patients received adalimumab induction then 40 mg fortnightly. Patients underwent colonoscopy at 6 months with endoscopic recurrence assessed blind to treatment.

RESULTS

A total of 101 patients [50% male; median (IQR) age 36 (25-46) years] were included. There were no differences in disease history between thiopurine- and adalimumab-treated patients. Fifteen patients withdrew prior to 6 months, five due to symptom recurrence (of whom four were colonoscoped). Endoscopic recurrence (Rutgeerts score i2-i4) occurred in 33 of 73 (45%) thiopurine vs. 6 of 28 (21%) adalimumab-treated patients [intention-to-treat (ITT); P = 0.028] or 24 of 62 (39%) vs. 3 of 24 (13%) respectively [per-protocol analysis (PPA); P = 0.020]. Complete mucosal endoscopic normality (Rutgeerts i0) occurred in 17/73 (23%) vs. 15/28 (54%) (ITT; P = 0.003) and in 27% vs. 63% (PPA; P = 0.002). The most advanced disease (Rutgeerts i3 and i4) occurred in 8% vs. 4% (thiopurine vs. adalimumab).

CONCLUSIONS

In Crohn's disease patients at high risk of post-operative recurrence adalimumab is superior to thiopurines in preventing early disease recurrence.

Rapid response of severe refractory metastatic Crohn's disease to infliximab

A case is described of a middle-aged female who developed an aggressive form of biopsy-proven metastatic Crohn's disease involving the inguinal, perineal and submammary areas. Her condition had been unresponsive to topical and systemic corticosteroids, antibiotics, immunosuppressives, and repeated surgical debridement. Administration of infliximab resulted in a rapid clinical response with subjective improvements in pain and general well-being, and an objective decline in exudate, erythema and size of the lesions. Infliximab may be a suitable therapeutic option in patients with metastatic Crohn's disease.

Topography of a 2.0 A structure of alpha1-antitrypsin reveals targets for rational drug design to prevent conformational disease

Members of the serpin family of serine proteinase inhibitors play important roles in the inflammatory, coagulation, fibrinolytic, and complement cascades. An inherent part of their function is the ability to undergo a structural rearrangement, the stressed (S) to relaxed (R) transition, in which an extra strand is inserted into the central A beta-sheet. In order for this transition to take place, the A sheet has to be unusually flexible. Malfunctions in this flexibility can lead to aberrant protein linkage, serpin inactivation, and diseases as diverse as cirrhosis, thrombosis, angioedema, emphysema, and dementia. The development of agents that control this conformational rearrangement requires a high resolution structure of an active serpin. We present here the topology of the archetypal serpin alpha1-antitrypsin to 2 A resolution. This structure allows us to define five cavities that are potential targets for rational drug design to develop agents that will prevent conformational transitions and ameliorate the associated disease.

Familial dementia caused by polymerization of mutant neuroserpin

Aberrant protein processing with tissue deposition is associated with many common neurodegenerative disorders; however, the complex interplay of genetic and environmental factors has made it difficult to decipher the sequence of events linking protein aggregation with clinical disease. Substantial progress has been made toward understanding the pathophysiology of prototypical conformational diseases and protein polymerization in the superfamily of serine proteinase inhibitors (serpins). Here we describe a new disease, familial encephalopathy with neuroserpin inclusion bodies, characterized clinically as an autosomal dominantly inherited dementia, histologically by unique neuronal inclusion bodies and biochemically by polymers of the neuron-specific serpin, neuroserpin. We report the cosegregation of point mutations in the neuroserpin gene (PI12) with the disease in two families. The significance of one mutation, S49P, is evident from its homology to a previously described serpin mutations, whereas that of the other, S52R, is predicted by modelling of the serpin template. Our findings provide a molecular mechanism for a familial dementia and imply that inhibitors of protein polymerization may be effective therapies for this disorder and perhaps for other more common neurodegenerative diseases.

A kinetic mechanism for the polymerization of alpha1-antitrypsin

The mutation in the Z deficiency variant of alpha1-antitrypsin perturbs the structure of the protein to allow a unique intermolecular linkage. These loop-sheet polymers are retained within the endoplasmic reticulum of hepatocytes to form inclusions that are associated with neonatal hepatitis, juvenile cirrhosis, and hepatocellular carcinoma. The process of polymer formation has been investigated here by intrinsic tryptophan fluorescence, fluorescence polarization, circular dichroic spectra and extrinsic fluorescence with 8-anilino-1-naphthalenesulfonic acid and tetramethylrhodamine-5-iodoacetamide. These biophysical techniques have demonstrated that alpha1-antitrypsin polymerization is a two-stage process and have allowed the calculation of rates for both of these steps. The initial fast phase is unimolecular and likely to represent temperature-induced protein unfolding, while the slow phase is bimolecular and associated with loop-sheet interaction and polymer formation. The naturally occurring Z, S, and I variants and recombinant site-directed reactive loop and shutter domain mutants of alpha1-antitrypsin were used to demonstrate the close association between protein stability and rate of alpha1-antitrypsin polymerization. Taken together, these data allow us to propose a kinetic mechanism for alpha1-antitrypsin polymer formation that involves the generation of an unstable intermediate, which can form polymers or generate latent protein.

Anti-transglutaminase antibodies and coeliac disease

BACKGROUND

Anti-endomysial antibodies have high specificity for coeliac disease but measurements are limited by the requirement for monkey oesophagus, a substrate that is expensive, and of limited availability and ethical acceptance. Tissue transglutaminase has recently been identified as the endomysial autoantigen in coeliac disease.

AIMS

To examine the validity of serum tissue transglutaminase antibody levels in patients with coeliac disease and to assess their sensitivity and specificity against standard serological tests.

METHODS

Serum IgA anti-tissue transglutaminase antibody titres (measured by ELISA), IgA anti-gliadin antibody titres (measured by a commercial ELISA) and anti-endomysial antibody titres (measured by indirect immunofluorescence) were determined in 46 untreated and 14 treated patients biopsy-proven coeliac disease and 145 disease and healthy controls.

RESULTS

All patients with untreated coeliac disease were positive for anti-endomysial and anti-tissue transglutaminase antibodies (sensitivity 100%). Seventy-one per cent of treated coeliac patients were anti-tissue transglutaminase antibody negative. Five of 145 disease and healthy controls had low titres of anti-tissue transglutaminase antibody (specificity 97%); no controls were anti-endomysial antibody positive.

CONCLUSIONS

Our results demonstrated the sensitivity and specificity of IgA anti-tissue transglutaminase antibodies to correlate highly with anti-endomysial antibodies in the diagnosis of coeliac disease. The ELISA for IgA anti-tissue transglutaminase antibodies is quantitative and easy to perform and is a valid alternative to indirect immunofluorescence for anti-endomysial antibodies in screening for suspected coeliac disease.

Proteasome blockers inhibit TNF-alpha release by lipopolysaccharide stimulated macrophages and microglia: implications for HIV-1 dementia

HIV-1 infection of the central nervous system can cause severe neurologic disease although only microglial cells and brain macrophages are susceptible to productive viral infection. Substances secreted by infected cells are thought to cause disease indirectly. Tumor necrosis factor alpha (TNF-alpha) is one candidate neurotoxin and is upregulated during HIV-1 infection of the brain, likely via activation of the transcription factor NF-kappaB. We used the proteasome inhibitors, MG132 and ALLN (N-acetyl-Leu-Leu-Norleucinal), to inhibit NF-kappaB activation in primary human fetal microglia (PHFM) and primary monocyte derived-macrophages, and showed that they could block TNF-alpha release stimulated by lipopolysaccharide (LPS) or TNF-alpha. In addition, we performed electrophoretic mobility shift analysis and determined that in microglia, the p50/p65 heterodimer of NF-kappaB is activated by LPS stimulation, and is inhibited by MG132. Thus, blockade of NF-kappaB activation in microglia in vitro can decrease production of TNF-alpha and may prove to be a novel strategy for treating HIV-1 dementia.

Lung polymers in Z alpha1-antitrypsin deficiency-related emphysema

Patients with alpha1-antitrypsin (alpha1-AT) deficiency are at risk of developing early-onset panlobular basal emphysema, which has been attributed to uncontrolled proteolytic activity within the lung. Severe genetic deficiency of alpha1-AT is most commonly due to the Z mutation (342Glu--> Lys), which results in a block in alpha1-AT processing within the endoplasmic reticulum of hepatocytes. The retained alpha1-AT forms inclusions, which are associated with neonatal hepatitis, juvenile cirrhosis, and hepatocellular carcinoma. Our recent studies have shown that the accumulation of alpha1-AT is due to the Z mutation perturbing the structure of alpha1-AT to allow polymer formation, with a unique linkage between the reactive center loop of one alpha1-AT molecule and the A beta-pleated sheet of a second. The detection of loop-sheet polymers and other conformations of alpha1-AT in the lungs of patients with emphysema has been technically difficult. We show here that transverse urea-gradient-gel (TUG) electrophoresis and Western blot analysis may be used to characterize conformations of alpha1-AT in dilute samples of bronchoalveolar lavage fluid (BALF). This technique was used to demonstrate loop-sheet polymers in the lungs of patients with Z alpha1-AT-deficiency-related emphysema. Polymers were the predominant conformational form of alpha1-AT in BALF from the lungs of two of five Z homozygotes with emphysema, but were not detectable in any of 13 MM, MS, or MZ alpha1-AT controls. Because alpha1-AT loop-sheet polymers are inactive as proteinase inhibitors, this novel conformational transition will further reduce the levels of functional proteinase inhibitor in the lungs of the Z alpha1-AT homozygote, and so exacerbate tissue damage.

Wild-type alpha 1-antitrypsin is in the canonical inhibitory conformation

alpha 1-Antitrypsin is the archetypal member of the serine proteinase inhibitor or serpin superfamily. Members of the family show structural homology based on a dominant A beta-sheet and a mobile reactive centre loop. Our recent crystal structure of alpha 1-antitrypsin stabilized with a point mutation showed the loop to be in a canonical inhibitory conformation in the absence of significant insertion into the A beta-sheet. It could be argued that the stabilizing mutation may induce the reactive centre loop to adopt an artificial, and unrepresentative, conformation and the finding seems to be at variance with studies assessing rates of peptide insertion into the A beta-sheet and limited proteolysis of the reactive loop. Here we present a 2.9 A structure of recombinant wild-type alpha 1-antitrypsin with no stabilizing mutations. Again, the reactive loop is in a canonical conformation in the absence of significant insertion into the A beta-sheet. A stabilizing salt bridge between P5 glutamate and arginine residues 196, 223 and 281, already identified in the mutant, provides strong evidence that this conformation is not an artefact of crystallization but represents the conformation of the circulating inhibitor in vivo. Comparison with the structure of alpha 1-antitrypsin stabilized with the Phe51Leu mutation indicates that the increased thermal stability of the mutant results from enhanced packing of aromatic residues in the hydrophobic core of the molecule. The structure of wild-type alpha 1-antitrypsin reveals a hydrophobic pocket between s2A and helices D and E that is filled on reactive loop insertion and the formation of biologically relevant loop-sheet polymers. This pocket may provide a target for rational drug design to prevent the formation of polymers and the associated plasma deficiency, liver cirrhosis and emphysema.

Commercial plasma alpha1-antitrypsin (Prolastin) contains a conformationally inactive, latent component

Fractionated plasma alpha1-antitrypsin is widely-used as replacement therapy in patients with Z alpha1-antitrypsin deficiency-related emphysema. We have recently shown that purified antitrypsin may be induced to adopt an inactive latent conformation by heating at high temperatures in stabilizing concentrations of sodium citrate. Such a conformation was predicted to be present in commercial preparations of antitrypsin, as these require heating under similar conditions for viral inactivation. Native antitrypsin was purified from plasma, and commercial antitrypsin (Prolastin) was obtained from Bayer Corporation. Western blot analysis of transverse urea gradient (TUG) gels showed that commercial antitrypsin migrated as two bands: one with an unfolding profile of native antitrypsin and the second with a profile of latent antitrypsin. A latent fraction, comprising approximately 8% of the total antitrypsin, was separated from the native antitrypsin in Prolastin by anion exchange chromatography. The specific activity of this latent form against bovine alpha-chymotrypsin increased from 1 to 2% to 50% over 3 h after refolding from 6 M guanidine hydrochloride. These data show that commercial antitrypsin contains a latent component. The significance of this conformation in vivo is unknown, although Prolastin has shown few adverse side-effects in prolonged clinical usage.

Commercial plasma alpha1-antitrypsin (Prolastin) contains a conformationally inactive, latent component

Fractionated plasma alpha1-antitrypsin is widely-used as replacement therapy in patients with Z alpha1-antitrypsin deficiency-related emphysema. We have recently shown that purified antitrypsin may be induced to adopt an inactive latent conformation by heating at high temperatures in stabilizing concentrations of sodium citrate. Such a conformation was predicted to be present in commercial preparations of antitrypsin, as these require heating under similar conditions for viral inactivation. Native antitrypsin was purified from plasma, and commercial antitrypsin (Prolastin) was obtained from Bayer Corporation. Western blot analysis of transverse urea gradient (TUG) gels showed that commercial antitrypsin migrated as two bands: one with an unfolding profile of native antitrypsin and the second with a profile of latent antitrypsin. A latent fraction, comprising approximately 8% of the total antitrypsin, was separated from the native antitrypsin in Prolastin by anion exchange chromatography. The specific activity of this latent form against bovine alpha-chymotrypsin increased from 1 to 2% to 50% over 3 h after refolding from 6 M guanidine hydrochloride. These data show that commercial antitrypsin contains a latent component. The significance of this conformation in vivo is unknown, although Prolastin has shown few adverse side-effects in prolonged clinical usage.

Inhibitory conformation of the reactive loop of alpha 1-antitrypsin

The reactive site loop of the serpin family of serine proteinase inhibitors is flexible and can adopt a number of diverse conformations. A 2.9 A resolution structure of alpha 1-antitrypsin-the principal proteinase inhibitor in human plasma-shows the loop in a stable canonical conformation matching that found in all other families of serine proteinase inhibitors. This unexpected finding in the absence of loop insertion into the body of the molecule favours a two-stage mechanism of inhibition and provides a model for the heparin activation of antithrombin. The beta-pleated strand conformation of the loop also accounts for the polymerization of the serpins in disease and for their association with other beta-sheet structures, most notably the beta-amyloid of Alzheimer's disease.

Handwashing practice in nurse education

Handwashing is the single most important clinical procedure. There is a discrepancy between nurses' knowledge of handwashing and their practice. The selection of an appropriate teaching method is important and should be reflected within the curriculum.

alpha 1-Antitrypsin Mmalton (Phe52-deleted) forms loop-sheet polymers in vivo. Evidence for the C sheet mechanism of polymerization

The Z (Glu342-->Lys) and Siiyama (Ser53-->Phe) deficiency variants of alpha 1-antitrypsin result in the retention of protein in the endoplasmic reticulum of the hepatocyte by loop-sheet polymerization in which the reactive center loop of one molecule is inserted into a beta-pleated sheet of a second. We show here that antitrypsin Mmalton (Phe52-deleted), which is associated with the same liver inclusions, is also retained at an endoglycosidase H-sensitive stage of processing in the Xenopus oocyte and spontaneously forms polymers in vivo. These polymers, obtained from the plasma of an Mmalton/QO (null) bolton heterozygote, were much shorter than other antitrypsin polymers and contained a reactive center loop-cleaved species. Monomeric mutant antitrypsin was also isolated from the plasma. The monomeric component had a normal unfolding transition on transverse urea gradient gel electrophoresis and formed polymers in vitro more readily than M, but less readily than Z, antitrypsin. The A beta-sheet accommodated a reactive center loop peptide much less readily than Z antitrypsin, which in turn was less receptive than native M antitrypsin. The nonreceptive conformation of the A sheet in antitrypsin Mmalton had little effect on kinetic parameters, the formation of SDS-stable complexes, the S to R transition, and the formation of the latent conformation. Comparison of the results with similar findings of short chain polymers associated with the antithrombin variant Rouen VI (Bruce, D., Perry, D., Borg, J.-Y., Carrell, R. W., and Wardell, M. R. (1994) J. Clin. Invest. 94, 2265-2274) suggests that polymerization is more complicated than the mechanism proposed earlier. The Z, Siiyama, and Mmalton mutations favor a conformational change in the antitrypsin molecule to an intermediate between the native and latent forms. This would involve a partial overinsertion of the reactive loop into the A sheet with displacement of strand 1C and consequent loop-C sheet polymerization.

Preparation and characterization of latent alpha 1-antitrypsin

Members of the serine proteinase inhibitor or serpin superfamily have a common molecular architecture based on a dominant five-membered A beta-pleated sheet and a mobile reactive center loop. The reactive center loop has been shown to adopt a range of conformations from the three turn alpha-helix of ovalbumin to the cleaved or latent inhibitor in which the reactive center loop is fully inserted into the A sheet of the molecule. While the cleaved state can be achieved in all inhibitory serpins only plasminogen activator inhibitor-1 and, more recently, antithrombin have been shown to adopt the latent conformation. We show here that the archetypal serpin, alpha 1-antitrypsin, can also be induced to adopt the latent conformation by heating at high temperatures in 0.7 M citrate for 12 h. The resulting species elutes at a lower sodium chloride concentration on an anion-exchange column and has a more cathodal electrophoretic mobility on non-denaturing polyacrylamide gel electrophoresis and isoelectric focusing than native M antitrypsin. Latent antitrypsin is inactive as an inhibitor of bovine alpha-chymotrypsin, is stable to unfolding with 8 M urea, and is more resistant to heat-induced loop-sheet polymerization than native but less resistant than cleaved antitrypsin. The reactive center loop of latent antitrypsin is inaccessible to proteolytic cleavage, and its occupancy of the A sheet prevents the molecule accepting an exogenous reactive center loop peptide. The activity of latent antitrypsin may be increased from < 1% to approximately 35% by refolding from 6 M guanidinium chloride.

A figurehead that leads by example. Effective leadership through the management of resources

A figurehead that leads by example: effective leadership through the management of resources. Professional Nurse, 9, 2, 80-84. 1. It is essential that encouragement and praise are given where appropriate. 2. It is important to support teams, even if they fail. 3. Managers need to be flexible in their thoughts and actions. 4. Managers are also required to be vigilant to what is happening around them and to the needs of the team.

Autoantibodies to neutrophil cytoplasmic (ANCA) and endothelial cell surface antigens (AECA) in chronic inflammatory bowel disease

Sera from 103 patients with chronic inflammatory bowel disease (IBD) were tested prospectively for antibodies against neutrophil cytoplasmic antigens (anti-neutrophil cytoplasm antibodies, ANCA) and endothelial cell surface antigens (anti-endothelial cell antibodies, AECA) by indirect immunofluorescence (IIF) and assays based on whole fixed neutrophils, purified neutrophil enzyme substrates and human umbilical vein endothelial cells. Using IIF, ANCA were found in 26 IBD sera (25%) and in none of 51 controls. Twenty-two positive sera (85%) were from patients with ulcerative colitis (UC). The pattern of distribution of immunofluorescence was always perinuclear (P-ANCA). A majority of UC patients positive for these autoantibodies (68%) had active colitis, but none had evidence of vasculitis. Using a whole neutrophil ELISA, binding was demonstrable in 73% of UC sera compared to 27% of Crohn's (CD) sera and only 4% of controls. Unlike vasculitis sera, UC sera with P-ANCA did not bind strongly to myeloperoxidase (MPO). Forty-five per cent of IBD sera tested positive for IgG AECA in an endothelial cell ELISA, compared to seven of 51 (14%) controls. Binding correlated with both active and extensive colitis. A type of P-ANCA, in most cases distinct from MPO-specific P-ANCA observed in vasculitis, is detected in a significant proportion of patients with UC, but rarely Crohn's colitis and therefore may be of differential diagnostic value. IgG AECA are also frequent in CIBD sera but are less disease specific than ANCA.

Handwashing: a process of judgement and effective decision-making

It is well-known that regular handwashing is an effective way of reducing cross-infection. Healthcare professionals need to be encouraged to evaluate their practice in the light of research-based evidence of their patients' needs, so improvements can be made.

The microbial flora of the rectal mucosa and faeces of patients with Crohn's disease before and during antimicrobial chemotherapy

The faecal flora and mucosa-associated flora (MAF) of rectal biopsy material from 12 patients with active Crohn's disease were studied before and during treatment with a combination of metronidazole and cotrimoxazole given orally for at least 2 weeks. The total faecal flora was greater than the MAF although the proportions of bacterial groups were similar. The changes observed during treatment were: obligate anaerobes such as Bacteroides spp. decreased in faeces (p less than 0.05) and in MAF (p less than 0.02); the total count of facultative bacteria increased in the faeces (p less than 0.002) but not in the MAF. Streptococci, predominantly enterococci, increased significantly in faeces (p less than 0.001) and in MAF (p less than 0.02) such that they became predominant components of these florae. Facultative gram-negative bacilli were unaltered in faeces but significantly reduced in the MAF (p less than 0.05). Sporing clostridia were infrequently isolated from the MAF but were significantly reduced in the faeces (p less than 0.01). During the treatment period, eight of the 12 patients showed clinical improvement, but this could not be related to the site or extent of disease or to specific changes in faecal flora or MAF. This combination of antibacterial agents causes profound alterations to the bacterial flora of mucosa and faeces and these changes may help to define the role of bacteria in the pathogenesis of Crohn's disease.

Plasma prednisolone levels during intravenous therapy in acute colitis

Maximum plasma levels in six acute colitics were about three times greater after an intravenous bolus of 20 mg prednisolone than the mean level achieved during infusion of the same dose (p<0.001) over eight hours; the level during infusion was about twice as great as the maximum recorded previously after a single 40 mg oral dose of prednisolone. These findings favour the use of intravenous administration in severe acute colitis. No difference was found between plasma levels of patients and six normal subjects after the intravenous bolus.

Colonoscopic diagnosis of minimal change colitis in patients with a normal sigmoidoscopy and normal air-contrast barium enema

8 patients with normal sigmoidoscopic appearances and normal results by high-quality air contrast barium enema had substantial or total colitis diagnosed for the first time at colonoscopy performed within a month of the radiological examination. Colitis was confirmed in all 8 patients by histological examination of biopsy specimens. Barium enema radiographs were independently reviewed by three experienced observers who also reviewed other normal and abnormal radiographs. One observer regarded all 8 sets of radiographs from the patients with colitis as being of normal appearance, and 4 patients were reported as having normal radiographs by all three observers. All 7 of the rectal biopsy specimens taken showed histological features of inflammatory bowel disease. This emphasises the importance of performing a rectal biopsy in patients with gastrointestinal symptoms of unknown cause.

Chlamydiae and inflammatory bowel disease

No association was found between inflammatory bowel disease and infection with C. trachomatis or C. psittaci when patients were tested for the presence of these organisms using immunohistological, cell culture isolation, and serological techniques.

Prednisolone absorption in acute colitis

Peak plasma levels were reduced after an oral dose of 40 mg prednisolone in six patients with severe acute colitis as compared with six normal subjects, though total absorption appeared to be similar; the findings suggest that prednisolone absorption was delayed in acute colitis. A dilutional fall in plasma albumin was observed in normal subjects and in the patients after 40 mg prednisolone by mouth.

Comparison of exercise responses of males and females during acute exposure to hypobaria

Seventeen male and 20 female college students were tested on a bicycle ergometer in a hypobaric chamber to determine whether both sexes had similar submax and max exercise responses to acute hypoxia. Initial testing was at a terrestrial altitude of 1576 m, to which the subjects were acclimated; subsequent tests were at simulated altitudes of 2743 m and 3962 m. Analysis of covariance showed that inspired V was the only variable during submaximal work (50% max) to exhibit a significant difference in altitude response between males and females; women had a smaller increase than men. During max work, V and O2 pulse increased less in women. At 2743 m, max VO2 decreased more in females whereas, at 3962 m, no difference was noted. It was concluded that during both submaximal and maximal work with acute altitude exposure, women would demonstrate smaller relative increases in ventilation than would men.

Unusual cause of central dislocation of the hip

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