Effective animal health disease surveillance using a network-enabled approach.

There are many benefits that derive from real-time knowledge of the health status of the national livestock population. Effective animal disease surveillance is a requirement for countries that trade in live animals and their products in order to comply with the World Organization for Animal Health (OIE) guidelines. Rapid identification of introduced and emerging disease allows rapid response and mitigation of the economic consequences. Connections between animal and human disease caused by a common pathogen can be recognized and control measures implemented, thereby protecting public health and maintaining public confidence in the food supply. Production-limiting diseases can be monitored, and control programmes be evaluated with benefits accruing from decreased economic losses associated with disease as well as reducing the welfare concerns associated with diseased animals. Establishing a surveillance programme across a wide area with diverse ecosystems and political administrations as Canada is a complex challenge. When funding became available from a government programme to enable early detection of a bio-terrorist attack on livestock, the Canadian Animal Health Surveillance Network (CAHSN) became officially established. An existing web-based information platform that supports intelligence exchange, surveillance and response for public health issues in Canada was adapted to link the network animal health laboratories. A minimum data set was developed that facilitated sharing of results between participating laboratories and jurisdictions as the first step in creating the capacity for national disease trend analysis. In each of the network laboratories, similar quality assurance and bio-containment systems have been funded and supported, and diagnostic staff have been trained and certified on a suite of diagnostic tests for foreign animal diseases. This ensures that national standards are maintained throughout all of the diagnostic laboratories. This paper describes the genesis of CAHSN, its current capability and governance, and potential for future development.

New measurement of the K+-->pi+ nunu branching ratio.

Three events for the decay K+-->pi+ nunu have been observed in the pion momentum region below the K+-->pi+pi0 peak, 140 < Ppi < 199 MeV/c, with an estimated background of 0.93+/-0.17(stat.) -0.24+0.32(syst.) events. Combining this observation with previously reported results yields a branching ratio of B(K+-->pi+ nunu) = (1.73(-1.05)+1.15) x 10(-10) consistent with the standard model prediction.

Measurement of the Michel parameter rho in muon decay.

The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models.

Improved measurement of the K+-->pi+nunu; branching ratio.

An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events observed in the pion momentum region 211

The effects of gamma interferon on replication of foot-and-mouth disease virus in persistently infected bovine cells.

Foot-and-mouth disease virus (FMDV) causes a highly contagious viral disease of cloven-hoofed animals, which has a considerable socio-economic impact on the countries affected. In addition, persistent infection can occur following clinical or sub-clinical disease in either vaccinated or non-vaccinated cattle. The mechanism(s) by which FMDV persistence is established and maintained is not fully understood. To better understand the basic mechanisms controlling the virus infection in cattle, the effects of interferon gamma (IFN-gamma) on the replication of FMDV was evaluated in vitro in persistently infected-epithelial cells isolated from FMDV infected cattle. Initially primary bovine thyroid (BTY) cells were treated with varying doses of bovine recombinant IFN-gamma. The cytokine activity was measured by detection of viral antigen in cell supernatants and viral RNA expression compared with cells without INF-gamma treatment. Pretreatment with IFN-gamma profoundly affected FMDV growth in BTY cells. The replication of FMDV was affected in the presence of more than 2.5 u/ml of IFN-gamma and the effect was both dose-dependent and related to the time of exposure. Analysis of the mechanism of inhibition suggests that IFN-gamma did not inhibit the viral replication through induction of nitric oxide. More interesting is the finding that continuous treatment with IFN-gamma severely restricts FMDV replication or even cures persistently infected bovine epithelial cells, indicating that a cytokine-mediated pathway may be involved in the in vivo clearance of persistent FMDV.

Upregulated eotaxin expression and T cell infiltration in the basal and papillary epithelium in cows' milk associated reflux oesophagitis.

BACKGROUND: Cows' milk sensitive reflux oesophagitis is an emerging clinical entity in children, normally indistinguishable from primary gastro-oesophageal reflux (GOR) apart from the response to dietary antigen exclusion. It is conjectural whether a tendency towards mucosal eosinophilia distinguishes this group from primary GOR. AIMS: To determine whether there may be differences in the mucosal lesion within the oesophagus in those children with reflux in association with cows' milk induced small bowel pathology, particularly in relation to the eosinophil chemokine eotaxin. METHODS: A total of 29 children underwent endoscopic assessment, including nine with cows' milk sensitive enteropathy (CMSE) and associated GOR, seven histologically normal controls, six with primary GOR, and seven disease controls. Oesophageal biopsy specimens were examined immunohistochemically for the chemokines eotaxin and MCP-2, and T cell lineage and activation markers. RESULTS: Strong upregulation of eotaxin expression, limited to basal and papillary epithelium, occurred in all CMSE patients. By contrast, weak expression was seen in a minority of controls and in 50% of primary GOR patients. Infiltration of CD3, CD4, and CD8 lymphocytes occurred in similar distribution in CMSE patients, significantly increased above controls. Significant upregulation of activation markers (CD25, HLA-DR) was also seen in the CMSE group within basal and papillary epithelium compared to controls and primary GOR. CONCLUSION: Basal and papillary epithelial eotaxin expression, with focal lymphocyte activation, was seen in infants with CMSE associated GOR. This preliminary study provides early evidence to suggest a pathogenesis distinct from primary GOR, in which specific recruitment of T cells and eosinophils may contribute to oesophageal dysmotility.

Further evidence for the decay K+ -->pi+nu(nu).

Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).

Virulence of swine vesicular disease virus is determined at two amino acids in capsid protein VP1 and 2A protease.

To identify the genetic determinants of virulence for swine vesicular disease virus, a panel of recombinant and site-directed mutant viruses were constructed from cDNA clones of a virulent J1'73 strain and an avirulent H/3'76 strain. Initial studies mapped the genetic determinants of virulence to either or both of the two sites at nucleotide (nt) 2842, encoding VP1-132, and nt 3355, encoding 2A-20. To determine their relative importance with regard to virulence, viruses mutated at either of these two sites from the avirulent to the virulent genotype and vice versa were tested in pigs. Viruses, mutated at nt 2842 to the virulent genotype (vSVLS104MJ1) or mutated at nt 3355 to the virulent genotype (vSVLS201MJ1), slightly recovered virulence but were very weak compared with viruses with site-directed mutations at both sites (vSVLS104/201MJ1). On the other hand, viruses, mutated at nt 2842 to the avirulent genotype (vSVLS104M00) or mutated at nt 3355 to the avirulent genotype (vSVLS201M00), did not have attenuated virulence. Sequence analysis of viruses recovered from inoculated pigs revealed that reversion at nt 3355 to the virulent genotype occurred in pigs which had been inoculated with vSVLS201M00. These results suggested that both amino acids determined the virulent phenotype, but that the 2A-20 site might be the major determinant for virulence.

Measurement of direct photon emission in K+-->pi(+)pi(0)gamma decay

We have performed a measurement of the K+-->pi(+)pi(0)gamma decay and have observed 2x10(4) events. The best fit to the decay spectrum gives a branching ratio for direct photon emission of (4.7+/-0.8+/-0. 3)x10(-6) in the pi(+) kinetic energy region of 55 to 90 MeV and requires no component due to interference with inner bremsstrahlung.

Consistency in the observation of features used to classify duct carcinoma in situ (DCIS) of the breast.

AIM: To determine interobserver and intra-observer agreement in the assessment of cytological grade and intraduct necrosis in pure duct carcinoma in situ (DCIS) of the breast. METHODS: Sixty unselected cases with illustrated diagnostic criteria were circulated to 19 practising histopathologists. RESULTS: Overall agreement was moderate for cytological grade in three categories: 71% agreement; weighted kappa (kappa w), 0.36; intraduct necrosis in three categories (absent, present, extensive): 76% agreement; kappa w, 0.57; and the Van Nuys classification system: 73% agreement; kappa w, 0.48. Agreement was no better among observers participating in the National External Quality Assurance Programme. Intra-observer agreement for cytological assessment (69.6% agreement; kappa w, 0.52) and intraduct necrosis (68.3% agreement; kappa w, 0.48) was moderate, suggesting that individual variation rather than precision of criteria contributes to the lack of agreement. CONCLUSIONS: Moderate agreement on observations can be achieved by non-specialist pathologists, with better agreement on necrosis than cytological grade. There was evidence of consistent individual bias towards over or under scoring cytological grade, which could be corrected with adequate and prompt feedback.

A sensitive method for the detection of foot and mouth disease virus by in situ hybridisation using biotin-labelled oligodeoxynucleotides and tyramide signal amplification.

An in situ hybridisation technique, based on oligodeoxynucleotide probes and tyramide signal amplification, is described for the detection of foot and mouth disease virus RNA in infected cells. Biotinylated oligodeoxynucleotide probes, with and without tyramide signal amplification, were compared. The tyramide signal amplification detection enhances by at least 100-fold the sensitivity of in situ hybridisation.

Mucosal healing and a fall in mucosal pro-inflammatory cytokine mRNA induced by a specific oral polymeric diet in paediatric Crohn's disease.

BACKGROUND: Although enteral nutrition is a recognized form of treatment for intestinal Crohn's disease, there are persisting problems with feed palatability and only limited data as to its mode of action. AIM: To assess the effects of a specific oral polymeric diet (CT3211; Nestle, Vevey, Switzerland), which is rich in transforming growth factor beta2, on the mucosal inflammatory process. METHODS: Twenty-nine consecutive children with active intestinal Crohn's disease were treated with CT3211 as the sole source of nutrition for 8 weeks. Patients were assessed clinically, and endoscopically, whilst cytokine mRNA was measured in mucosal biopsies before and after treatment by quantitative reverse transcriptase polymerase chain reaction. RESULTS: After 8 weeks 79% of children were in complete clinical remission. Macroscopic and histological healing in the terminal ileum and colon was associated with a decline in ileal and colonic interleukin-1beta mRNA (pre-treatment to post-treatment ratio 0.008 and 0.06: P < 0.001, P = 0.006). In the ileum there was also a fall in interferon gamma mRNA (ratio 0.15, P < 0.001) with a rise in transforming growth factor beta1 mRNA (ratio 10, P = 0.04), whilst in the colon interleukin-8 mRNA fell with treatment (ratio 0.06, P < 0.05). CONCLUSIONS: The clinical response to oral polymeric diet CT3211 is associated with mucosal healing and a down regulation of mucosal pro-inflammatory cytokine mRNA in both the terminal ileum and colon. In the ileum there was also an increase in transforming growth factor beta1 mRNA.

Are endoscopic biopsies of small bowel as good as suction biopsies for diagnosis of enteropathy?

BACKGROUND: Endoscopy is increasingly used in paediatric practice for diagnosis of enteropathy, although the quality of grasp forceps-obtained biopsy specimens required for reliable diagnosis has been questioned in comparison with suction capsule biopsy specimens. This study prospectively compared the diagnostic suitability of grasp forceps biopsy versus suction biopsy in the same patient during the same procedure. METHODS: A double-port paediatric suction biopsy capsule was front-loaded onto an endoscope and directed to the fourth part duodenum-proximal jejunum for biopsy sampling. Subsequently, three grasp biopsy specimens were taken from the same region. All biopsies were coded, photographed, and measured for area, using computed morphometry. A single blinded histopathologist assessed sample adequacy for diagnosis. Twenty-nine patients were enrolled (age range, 8-185 months). RESULTS: On three occasions the suction capsule failed to fire, and on four occasions only one sample was obtained. Three grasp biopsy specimens were obtained on each occasion by endoscopy, and the first two were used for comparison with suction biopsy samples. Median total area of individual biopsy samples obtained by the two procedures was not different (21.3 vs. 22.5 mm2; P = 0.027). Muscularis mucosae was obtained more commonly with grasp biopsies (P<0.001), and no difference was observed for the presence of three or more villus-crypt units, degree of haemorrhage, or optimal orientation. Two suction biopsy procedures and one grasp biopsy procedure were inadequate for diagnosis. CONCLUSIONS: Endoscopic grasp biopsies are perfectly adequate for the assessment of small intestinal histology. In addition, endoscopy affords advantage in diagnosis of other upper gastrointestinal disease with avoidance of radiologic screening involved with the suction capsule technique.

Adrenocortical oncocytoma.

The histopathology and ultrastructural features of an adrenocortical oncocytoma are reported. The tumour was discovered incidentally during investigation for hypertension in a 72 year old female. Oncocytic tumours of the adrenal cortex are rare, with only 20 examples described in English language reports. Most have been non-functioning and benign, like the present example. Molecular studies may help assess the significance of oncocytic change in the pathogenesis and behaviour of oncocytic neoplasms.

Mapping the genetic determinants of pathogenicity and plaque phenotype in swine vesicular disease virus.

A series of recombinant viruses were constructed using infectious cDNA clones of the virulent J1'73 (large plaque phenotype) and the avirulent H/3'76 (small plaque phenotype) strains of swine vesicular disease virus to identify the genetic determinants of pathogenicity and plaque phenotype. Both traits could be mapped to the region between nucleotides (nt) 2233 and 3368 corresponding to the C terminus of VP3, the whole of VP1, and the N terminus of 2A. In this region, there are eight nucleotide differences leading to amino acid changes between the J1'73 and the H/3'76 strains. Site-directed mutagenesis of individual nucleotides from the virulent to the avirulent genotype and vice versa indicated that A at nt 2832, encoding glycine at VP1-132, and G at nt 3355, encoding arginine at 2APRO-20, correlated with a large-plaque phenotype and virulence in pigs, irrespective of the origin of the remainder of the genome. Of these two sites, 2APRO-20 appeared to be the dominant determinant for the large-plaque phenotype but further studies are required to elucidate their relative importance for virulence in pigs.

Viruses produced from complementary DNA of virulent and avirulent strains of swine vesicular disease viruses retain the in vivo and in vitro characteristics of the parental strain.

A full-length cDNA copy of the genome of the pathogenic strain, J1'73, of swine vesicular disease virus (SVDV) was constructed and inserted into the plasmid pSVL to generate a recombinant plasmid pSVLSJ1. Infectious virus was produced following transfection of cultured mammalian cells with the plasmid. The recovered virus had the same in vitro properties as the parental strain with regard to antigenicity, plaque size on IBRS-2 cells and single-step growth. Pigs were experimentally infected with the parental virus, J1'73 strain, and viruses recovered from cells transfected with the plasmids pSVLSJ1 and pSVLS00 [Inoue T, Yamaguchi S, Saeki T, Sekiguchi K, J Gen Virol 71: 1,835-1,838 (1990)] corresponding to the pathogenic (J1'73) and non-pathogenic (H/3'76) Japanese strains of the SVDV, respectively. All pigs inoculated with the virus recovered from pSVLSJ1 produced clinical signs of similar severity to those inoculated with the parental J1'73 strain. In contrast, pigs inoculated with the virus recovered from pSVLS00 did not show any clinical signs. Viruses recovered from cells transfected with either pSVLSJ1 or pSVLS00 therefore retained the in vitro characteristics and the in vivo pathogenicity of their respective parental strains.