Modelling of control options for an outbreak of Mycoplasma gallisepticum in egg production: a decision support tool.

Mycoplasma gallisepticum (MG) is a bacterium that causes respiratory disease in chickens, leading to reduced egg production. A dynamic simulation model was developed that can be used to assess the costs and benefits of control using antimicrobials or vaccination in caged or free range systems. The intended users are veterinarians and egg producers. A user interface is provided for input of flock specific parameters. The economic consequence of an MG outbreak is expressed as a reduction in expected egg output. The model predicts that either vaccination or microbial treatment can approximately halve potential losses from MG in some circumstances. Sensitivity analysis is used to test assumptions about infection rate and timing of an outbreak. Feedback from veterinarians points to the value of the model as a discussion tool with producers.

Cost-benefit analysis model of badger (Meles meles) culling to reduce cattle herd tuberculosis breakdowns in Britain, with particular reference to badger perturbation.

Bovine tuberculosis (TB) is an important economic disease. Badgers (Meles meles) are the wildlife source implicated in many cattle outbreaks of TB in Britain, and extensive badger control is a controversial option to reduce the disease. A badger and cattle population model was developed, simulating TB epidemiology; badger ecology, including postcull social perturbation; and TB-related farm management. An economic cost-benefit module was integrated into the model to assess whether badger control offers economic benefits. Model results strongly indicate that although, if perturbation were restricted, extensive badger culling could reduce rates in cattle, overall an economic loss would be more likely than a benefit. Perturbation of the badger population was a key factor determining success or failure of control. The model highlighted some important knowledge gaps regarding both the spatial and temporal characteristics of perturbation that warrant further research.

Autoimmune hepatitis overlap syndromes: an evaluation of treatment response, long-term outcome and survival.

BACKGROUND: Primary sclerosing cholangitis/autoimmune hepatitis (PSC/AIH) and primary biliary cirrhosis/AIH (PBC/AIH) overlap syndromes are poorly defined variants of AIH. Few large patient series exist, and there are little data on long-term outcomes. AIM: To compare presentation, clinical course and outcome of patients with PSC/AIH and PBC/AIH, with patients with definite AIH. Methods Two hundred and thirty-eight AIH patients were compared with 10 PBC/AIH patients and 16 PSC/AIH patients presenting consecutively between 1971 and 2005 at a single centre. RESULTS: Autoimmune hepatitis patients were significantly more likely to present with jaundice (69.4% vs. 25%; P = 0.0145) than PBC/AIH patients. Median serum aspartate aminotransferase activity at presentation was higher in AIH patients compared with PBC/AIH and PSC/AIH patients respectively (620 vs. 94 vs. 224 IU/L; P < 0.05). PBC/AIH patients demonstrated no response to standard AIH therapy more frequently than AIH patients (25% vs. 0.8%; P = 0.0057). Significant reduction in survival was identified between patients with PSC/AIH and those without (hazard ratio: PSC/AIH vs. AIH = 2.08, PSC/AIH vs. PBC/AIH = 2.14; P = 0.039). CONCLUSIONS: Patients with PSC/AIH have severe disease and significantly worse prognosis than patients with AIH or PBC/AIH. Recognition and close follow-up of this cohort are warranted.

Differentiation of mononuclear precursors into osteoclasts on the surface of Si-substituted hydroxyapatite.

In healthy bone, resorption and synthesis are in perfect coordination. In previous studies we demonstrated that the incorporation of silicon into the hydroxyapatite (HA) lattice enhances the proliferation and differentiation of human osteoblasts. Therefore, the aim of this study was to demonstrate the effect of silicon-substituted HA (0.8 and 1.5 wt % Si-HA) on the differentiation of mononuclear cells into osteoclasts, using two different starting cultures, peripheral blood mononuclear cells (PBMC) and monocytes expressing the CD14 antigen (CD14+). Through this study, it was possible to demonstrate that Si-HA allows the differentiation of mononuclear cells into mature osteoclasts, independent of the starting culture, PBMC or CD14+. Most of the cells on the surface of the materials expressed osteoclastic markers: actin rings, several nuclei, positivity for tartrate-resistant acid phosphatase (TRAP), and vitronectin receptor. In the presence of osteoclasts, a higher release of calcium and phosphate into the medium from the 1.5 wt % Si-HA substrate was detected when compared to the HA substrate; therefore, these results indicate higher osteoclastic resorptive activity on the 1.5 wt % Si-HA surface. Si-HA can be resorbed by cellular mechanisms and have a stimulatory effect on osteoclasts, although the underlying mechanism is still poorly understood.

Focused parathyroid surgery with intraoperative parathyroid hormone measurement as a day-case procedure.

BACKGROUND: This study assessed the feasibility, efficacy and safety of focused parathyroidectomy combined with intraoperative parathyroid hormone (IOPTH) measurement in a day-case setting. METHODS: Over 28 months 50 consecutive patients (mean age 63 (range 33-92) years) with clear evidence of unifocal disease on sestamibi scanning or ultrasonography underwent unilateral neck exploration via a small lateral incision. Blood samples for measurement of IOPTH were taken at induction of anaesthesia, before adenoma excision and after adenoma excision (at 5, 10 and 20 min). Ten patients were discharged within 23 h and 40 patients on the day of surgery. RESULTS: A solitary adenoma was identified in all but one patient, with a mean operating time of 30 (range 16-57) min. After parathyroidectomy, IOPTH levels fell appropriately except in one patient with multiglandular hyperplasia. No patient developed symptomatic hypocalcaemia during the 2 weeks after operation, enabling cessation of oral supplements. All patients remained normocalcaemic on follow-up (mean 26 (range 8-84) weeks) and histological examination confirmed parathyroid adenoma (48 patients), hyperplasia (one) or carcinoma (one). CONCLUSION: After accurate preoperative localization of uniglandular disease, patients with primary hyperparathyroidism may be managed successfully and safely by focused parathyroidectomy with IOPTH measurement as a day-case procedure.

Characteristics of autoimmune hepatitis in patients who are not of European Caucasoid ethnic origin.

BACKGROUND: Significant diversity in disease severity has been identified for autoimmune disorders among different ethnic groups but there is a lack of data on autoimmune hepatitis (AIH) in populations other than those of European Caucasoid (EC) or Japanese extraction. AIMS: To assess the clinical features, response to therapy, and eventual outcome in AIH patients of non-EC ethnicity. METHODS: A retrospective review of a regularly updated database of patients with AIH referred to liver outpatient clinics at King's College Hospital, London, since 1983. RESULTS: Twelve patients were identified (10 female; six African, five Asian, one Arabic; median age at presentation 30 years (range 12-58)) who satisfied international criteria for type 1 (11 cases) or type 2 (one case) AIH. Nine (75%) had cholestatic serum biochemistry and three (25%) had mild biliary changes on liver biopsy without definitive features of primary biliary cirrhosis or cholangiographic evidence of primary sclerosing cholangitis. Four showed a complete biochemical response to standard prednisolone with or without azathioprine therapy, three partial, and five no response. Four have required liver transplantation for intractable disease. By comparison with 180 EC patients with definite AIH attending during the same period, the non-EC patients were younger (p<0.05), presented with cholestatic biochemistry (p=0.014), and morphological biliary features more frequently (p<0.0005) and showed a poorer initial response to standard therapy (p<0.0005). CONCLUSIONS: Clinical expression of AIH in non-EC patients seems to differ in important respects from that in EC or Japanese patients. Management of such patients is challenging and may require alternative or more aggressive treatment strategies.

Autoimmune liver diseases.

The differential diagnosis of the three disorders that are usually classified as autoimmune liver diseases, namely autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), requires careful exclusion of other causes of chronic liver disease together with the finding of suggestive patterns of abnormalities of serum biochemical parameters, immunoglobulin isotypes and 'conventional' non-organ-specific autoantibodies. Antimitochondrial antibodies (particularly those reacting with epitopes on the E2 components of the pyruvate dehydrogenase and other 2-oxo-acid dehydrogenase complexes), and some sub-specificities of antinuclear antibodies, are virtually pathognomonic of PBC. Anti-liver-kidney microsomal antibodies reacting with defined epitopes on the cytochrome isoform P4502D6 are relatively specific for a small sub-group of (so-called 'type 2') AIH. However, most of the other serological parameters lack specificity. Additionally, within and between each disease group there is wide variability, even among patients with comparable severity of liver damage. Thus, in many cases, liver histology and/orcholangiography is still required for definitive diagnoses or for assessing stage and severity of these disorders. A number of autoantibodies that are more directly related to the liver than the 'conventional' autoantibodies are showing promise as possibly more specific diagnostic markers of AIH. Commercial tests for some of these are under development and it is hoped that they will soon become widely available.

The role of post-translational modification in beta-amyloid precursor protein processing.

The beta-amyloid precursor protein (APP) plays a pivotal role in the early stages of neurodegeneration associated with Alzheimer's disease. An alteration in the processing pattern of the protein results in an increase in the generation of the 40-42-amino-acid beta-amyloid (A beta) peptide, which coalesces to form insoluble, extracellular amyloid deposits. A greater understanding of the factors that influence APP processing may assist in the design of effective therapeutic agents to halt progression of Alzheimer's disease. APP is a sialoglycoprotein with two potential N-linked glycosylation sites, one of which may contain a complex oligosaccharide chain. An alteration in the glycosylation state of APP by the generation of oligomannosyl oligosaccharides results in a decrease in the secretion of the neuroprotective, soluble form of the protein and a parallel increase in the deposition of the cellular protein within the perinuclear region of the cell. Conversely, the attachment of additional terminal sialic acid residues on to the oligosaccharide chain results in an increase in secretion of soluble APP (sAPP alpha). One factor that has been widely reported to alter APP processing is the activation of protein kinase C (PKC). This process has been characterized using synaptosomal preparations, which suggests that the PKC action is occurring at the level of the plasma membrane. Furthermore, when cells are transfected with the sialyltransferase enzyme, there is a direct relationship between the sialylation potential of APP and the fold stimulation of sAPP alpha, after PKC activation. These results suggest that the post-translational modification of APP by glycosylation is a key event in determining the processing of the protein.

Autoimmune hepatitis: Clinical manifestations and diagnostic criteria.

In 1998, the International Autoimmune Hepatitis Group--a panel of 40 hepatologists and hepatopathologists from 17 countries who have a particular interest in autoimmune hepatitis (AIH)--undertook a review, in light of subsequent experience, of the descriptive criteria and diagnostic scoring system that it had proposed in 1993 for the diagnosis of AIH. This review (published in 1999) noted that the original descriptive criteria appeared to be quite robust and required only relatively minor modifications to bring them up to date with developments and experience in diagnostic modalities for liver disease in general. Analysis of published data on the application of the original criteria in nearly 1000 patients revealed that the diagnostic scoring system had an overall diagnostic accuracy of 89.8%, with a sensitivity of 98.0%. Specificity for excluding definite AIH in patients with chronic viral hepatitis and circulating autoantibodies or patients with overlapping cholestatic syndromes was 98% to 100%, but specificity for excluding probable AIH in these disorders ranged from only 60% to 80%. Modifications, including adjustments to the weightings against biochemical and histological cholestatic features, have been made to the scoring system to improve its specificity.

Management and outcome of pregnancy in autoimmune hepatitis.

BACKGROUND: There is a paucity of data in the literature on the risks associated with, and optimal management of, pregnancy in patients with autoimmune hepatitis (AIH). AIMS: To assess maternal and fetal outcomes in relation to clinical management of pregnancy in a large cohort of patients with well defined AIH. METHODS: A review of all known pregnancies in 162 females with definite AIH attending our clinics between 1983 and 1998, with respect to treatment, natural history, and outcome. RESULTS: Thirty one live births (one twin) resulted from 35 pregnancies in 18 women (seven with cirrhosis). Median age at conception was 28 years (range 18-36). Two patients presented with AIH de novo during pregnancy. At conception, in 15 pregnancies patients had been receiving azathioprine alone or (in nine) with prednisolone, in seven prednisolone alone, and in one cyclosporin. Fetal loss at > or =20 weeks' gestation occurred in two instances. Flares in disease activity occurred during four pregnancies and within three months of delivery in a further four. Among the 31 children born (median follow up 10 years) only two abnormalities have been identified: Perthes' disease in one and severe mental and physical handicap in a second who was born prematurely following decompensation of the mother's liver disease. Neither mother was receiving azathioprine. CONCLUSIONS: Successful completion of pregnancy is a realistic expectation for patients with well controlled AIH. Treatment options vary, but azathioprine appears to be generally safe and without adverse outcomes for mother or baby. Vigilance is required, however, and patients need to be monitored carefully during pregnancy and for several months post partum.

The relative activities of the C2GnT1 and ST3Gal-I glycosyltransferases determine O-glycan structure and expression of a tumor-associated epitope on MUC1.

In breast cancer, the O-glycans added to the MUC1 mucin are core 1- rather than core 2-based. We have analyzed whether competition by the glycosyltransferase, ST3Gal-I, which transfers sialic acid to galactose in the core 1 substrate, is key to this switch in MUC1 glycosylation that results in the expression of the cancer-associated SM3 epitope. Of the three enzymes known to convert core 1 to core 2, by the addition of GlcNAc to GalNAc in core1 C2GnT1 is the dominant enzyme expressed in normal breast tissue. Expression of C2GnT1 is low or absent in around 50% of breast cancers, whereas expression of ST3Gal-I is consistently increased. Mapping of ST3Gal-I and C2GnT1 within the Golgi pathway showed some overlap. To examine functional competition, the enzymes were overexpressed in T47D cells, which normally make core 1-based structures, have no detectable C2GnT1 activity and express the SM3 epitope. Overexpression of C2GnT1 resulted in loss of binding of SM3 to MUC1, accompanied by a decrease in the GalNAc/GlcNAc ratio, indicative of a switch to core 2 structures. Transfection of a C2GnT1 expressing line with ST3Gal-I restored SM3 binding and reduced GlcNAc incorporation into MUC1 O-glycans. Thus, even when C2GnT1 is expressed, the O-glycans added to MUC1 become core 1-dominated structures, provided expression of ST3Gal-I is increased as it is in breast cancer.

HLA class II genotypes associated with chronic hepatitis C virus infection and response to alpha-interferon treatment in Poland.

AIMS/BACKGROUND: Recent evidence suggests that spontaneous clearance of hepatitis C virus (HCV) may be associated with the HLA DQB1*0301 allele but there is still some debate over the role of other alleles and HLA haplotypes in HCV infection. As this may best be resolved by studying genetically different populations, we have investigated HLA class II-encoded susceptibility and resistance to HCV infection in a relatively sedentary population of patients from northwestern Poland. METHODS: The distributions of HLA class II DRB1, DQA1, DQB1 and DPB1 alleles were determined by standard PCR-protocol in 129 unrelated patients with chronic hepatitis C (anti-HCV and HCV-RNA positive) and 103 healthy unrelated racially-matched control subjects. Fifty-five patients were treated with alpha-interferon (5 MIU thrice weekly for 6 months) out of whom 29 showed a complete response and 26 were non-responders. RESULTS: A significantly reduced frequency of the DQB1*0301 allele in the patients was observed (24.0% vs. 38.8%; p=0.015). Additionally, two different DR-DQ haplotypes were found to be associated with chronic HCV infection: DRB1*1501-DQA1*01-DQB1*0602 (24.0% vs. 12.6%; p= 0.027) and DRB1*0701-DQA1*0201-DQB1*02 (31.8 vs. 12.6%; p=0.0006), the latter difference being most pronounced in those patients who responded to alpha-interferon treatment (41.4% vs. 12.6%; p=0.00048). CONCLUSIONS: The results confirm the negative association between chronic HCV and DQB1*0301 and identify two novel genetic associations. In particular, the DRB1*0701-DQA1*0201-DQB1*02 haplotype is associated with both chronic infection and response to alpha-interferon. Interestingly, the same haplotype is reportedly associated with non-response to hepatitis B vaccination.

Inhibition of N-glycan processing alters axonal transport of synaptic glycoproteins in vivo.

Synaptic glycoproteins are synthesized and glycosylated in the neuronal cell body, and conveyed to terminals by fast axonal transport. We used the alpha-mannosidase inhibitor, 2-deoxymannojirimycin (dMan), to investigate the effects of disrupting N-glycan processing on the axonal trafficking of proteins in vivo. dMan significantly reduced rapid axonal transport in retinal ganglion cells to about 34% of control values 4h after metabolic labeling; at 8 h post-labeling the inhibition was reversed. 2-D gel analysis showed that dMan completely inhibited the arrival of radiolabeled L1 and NCAM at axon terminals, and resulted in the appearance of two novel proteins of 230 kDa and 155 kDa. Our results show that disruption of the N-glycosylation pathway has an immediate inhibitory effect on total axonal transport and longer lasting effects on the trafficking of specific glycoproteins to axon terminals in vivo.

Autoantibodies in alcoholic liver disease.

Despite many decades of research, the reasons why only a relatively small proportion of individuals who consume excessive quantities of alcohol develop clinically significant liver disease remain unknown. The association with features of autoimmune diseases, including hypergammaglobulinaemia, circulating autoantibodies, inheritance of certain immunogenetic (HLA) markers and response to corticosteroid therapy in some patients has led to a persistent impression that altered immune regulation with a relative loss of self-tolerance underlies susceptibility to the development of the more severe forms of alcoholic liver disease (alcoholic hepatitis and/or cirrhosis). However, review of the data from the numerous studies that have been conducted over the past 30 years fails to reveal sufficiently convincing evidence that autoimmunity plays a primary role in alcohol-related liver damage. In particular, most of the wide range of circulating autoantibodies that have been reported in patients are found mainly at low titres, are not confined to those with severe liver injury, and are probably more likely to be a response to the hepatic insult than causally related to liver damage. Additionally, an association with various HLA phenotypes has not been confirmed by meta-analysis. Interpretation is complicated by evidence that alcohol may have direct effects on some components of the immune system but, if there is an immunogenetic basis for alcoholic liver disease, the present evidence suggests that this might be related more to cytokine gene polymorphisms than to a predisposition to autoimmunity per se.

The selective enzymatic synthesis of lipophilic esters of swainsonine.

The potent and specific inhibitor of Golgi alpha-mannosidase II, swainsonine (SW) has been isolated in high yield from Swainsona procumbens and derivatised by regiospecific enzymatic reactions. In this study the regioselectivity of three commercially available enzymes, subtilisin Carlsberg, porcine pancreatic lipase (PPL) and Candida cylindracea lipase was determined for the acylation of swainsonine in predominantly anhydrous organic medium. The use of subtilisin in pyridine facilitated the single step synthesis of 2-O-butyryl-SW in a 23% yield, whilst catalysis by PPL in tetrahydrofuran gave 2-O-butyryl-SW (6%) and 1,2-di-O-butyryl-SW (31%).

Pathogenesis of autoimmune hepatitis.

Autoimmune hepatitis (AIH) is an idiopathic disorder affecting the hepatic parenchyma. There are no morphological features that are pathognomonic of the condition but the characteristic histological picture is that of an interface hepatitis without other changes that are more typical of other liver diseases. It is associated with hypergammaglobulinaemia, high titres of a wide range of circulating auto-antibodies, often a family history of other disorders that are thought to have an autoimmune basis, and a striking response to immunosuppressive therapy. The pathogenetic mechanisms are not yet fully understood but there is now considerable circumstantial evidence suggesting that: (a) there is an underlying genetic predisposition to the disease; (b) this may relate to several defects in immunological control of autoreactivity, with consequent loss of self-tolerance to liver auto-antigens; (c) it is likely that an initiating factor, such as a hepatotropic viral infection or an idiosyncratic reaction to a drug or other hepatotoxin, is required to induce the disease in susceptible individuals; and, (d) the final effector mechanism of tissue damage probably involves auto-antibodies reacting with liver-specific antigens expressed on hepatocyte surfaces, rather than direct T-cell cytotoxicity against hepatocytes.