Factors related to the incidence of clinical encephalomyocarditis virus (EMCV) infection on Belgian pig farms

We set up a matched case-control study of potential risk factors for clinical encephalomyocarditis virus (EMCV) in 58 pig farms in West Flanders (Belgium). In total, 29 farms experienced a clinical outbreak of EMCV confirmed by EMC virus isolation. Mortality was seen only among suckling piglets (18 case farms), in piglets and other age-groups (4 case farms), or only among fattening pigs (7 case farms). Five farms had reproductive problems among the sows. Control farms were matched geographically on farm size and farm type and were selected on the absence of clinical signs. A questionnaire on potential risk factors for EMCV was developed to collect data at both case and control farms. The exploration of the data used clusters of factors associated with clinical EMCV infection: (a) rodents, (b) general farm set up and (c) general hygiene. The multivariable relationships between clinical appearance of EMCV and potential risk factors were tested with conditional logistic regression. The final model on all farms contained presence of mice (OR=8.3) as a risk factor for clinical EMCV infection while the flow of manure up through the slatted floor (OR=0.11) and movement of manure between manure pits in the pig stable (OR=0.14) were protective.

The occurrence of encephalomyocarditis virus (EMCV) in European pigs from 1990 to 2001

The occurrence of encephalomyocarditis virus (EMCV) among domestic pigs and wild boar in several European countries is described and discussed. From 1990 to 2001 clinical outbreaks were analysed and serum samples, partly from existing screening programmes, were tested for antibodies against EMCV. Most clinical EMCV outbreaks were reported in Belgium (320), followed by Italy (110), Greece (15) and Cyprus (6). The outbreaks appeared to be clustered in 'endemic areas' with an increase in outbreaks during the autumn and winter months. The within-herd seroprevalence measured in clinically affected pig farms varied considerably among farms (2-87%), with age (0-84%) and by country. Data from farms with no clinical disease showed that subclinical infection with EMCV was found both within (seroprevalence 6-62%) and outside (up to 17 %) the endemic areas of the clinically affected countries as well as in the non-clinically affected countries Austria and France (3-5.4%). Among wild boar, the seroprevalence varied between 0.6 and 10.8%, and a study in Belgium found a prevalence of virus infection of 3.3%.

Transmission of encephalomyocarditis virus (EMCV) among pigs experimentally quantified

Two types of transmission experiments were performed to estimate the basic reproduction ratio R(0), indicating the level of encephalomyocarditis virus (EMCV) transmission among pigs. In a first experimental set-up with nine separate pairs, one randomly chosen piglet per pair was inoculated with a Belgian (myocardial) EMCV strain (B279/95, 10(3)TCID(50)/ml oronasally) and placed back into the pen. In the second experiment with two separate groups of five piglets, two piglets in each group were inoculated at the start. During the experiments, viraemia in blood and excretions was measured as well as the serological response against EMCV antigen. After death or euthanasia, the piglets were checked for heart lesions and virus isolation was done on various tissues. In both the experiments, the majority of the inoculated piglets either died with typical heart lesions (five out of nine and three out of four resp.), or produced high levels of neutralising antibody. EMC virus was isolated from the hearts of all piglets that died during either one of the experiments. The pairwise experiment revealed a point estimate for R(0) of 2.0 (95% confidence interval (CI)=0.37-10.74), while the group experiment resulted in a R(0)-value of 0.71 (95% CI=0.08-4.93). Combining the information from both experiments results in an estimate for R(0) of 1.24 (95% CI=0.39-4.35). Since R(0) has values around the threshold value of 1, the spread of EMCV due to contacts between pigs will in most cases be limited, but due to chance processes may lead to large outbreaks as well.

Role of reactive oxygen intermediates in the decrease of hepatic cytochrome P450 activity by serum of humans and rabbits with an acute inflammatory reaction

Serum of rabbits with a turpentine-induced acute inflammatory reaction (RS(INFLA)) and serum of humans with a viral infection (HS(INF)) were previously shown to diminish hepatic cytochrome P450 (P450) content and activity. To document the role of reactive oxygen intermediates in the serum-mediated decrease in P450 content and activity, hepatocytes of rabbits with an acute inflammatory reaction (H(INFLA)) were incubated with RS(INFLA) and HS(INF) for 4 h, and total P450 content (spectrally measurable P450), P450 activity (assessed by estimating the formation of theophylline metabolites), and amount of CYP1A1, CYP1A2, and CYP3A6 proteins were measured. RS(INFLA) or HS(INF) decreased P450 content and activity without affecting the amount of CYP1A1 and -1A2 H(INFLA). Exposure of H(CONT) or H(INFLA) to hydrogen peroxide (0.01-1.0 mM) and sodium nitroprusside (0.01-1.0 mM) produced a dose-dependent decrease in P450 content and in the formation of theophylline metabolites without modifying the amount of CYP1A1 and CYP1A2, whereas lipid peroxidation increased. Incubation of L-NAME (0.05-1.0 mM), dimethylthiourea (6.25-50 mM), or N-acetylcysteine (0.01-1.0 mM) with H(INFLA) partially prevented the decrease in P450 content and activity and the increased lipid peroxidation induced by RS(INFLA) and HS(INF). On the other hand, 3-amino-1,2,4-triazole (10-100 mM) or diethyldithiocarbamate (1.0-10 mM) potentiated RS(INFLA)- and HS(INF)-mediated decreases in P450 content and activity and the increase in lipid peroxidation, without affecting the amount of CYP1A1 or -1A2; DL-buthionine-(S,R)-sulfoximine (2.5-25 mM) potentiated only the inhibition of 1,3-dimethyluric acid formation. It is concluded that reactive oxygen intermediates are implicated in the decrease of H(INFLA) P450 content and activity induced by 4 h of exposure to RS(INFLA) or HS(INF).

Spatial and stochastic simulation to evaluate the impact of events and control measures on the 1997-1998 classical swine fever epidemic in The Netherlands. I. Description of simulation model

The simulation model InterCSF was developed to simulate the Dutch Classical Swine Fever (CSF) epidemic of 1997-98 as closely as possible. InterCSF is a spatial, temporal and stochastic simulation model. The outcomes of the various replications give an estimate of the variation in size and duration of possible CSF-epidemics. InterCSF simulates disease spread from an infected farm to other farms through three contact types (animals, vehicles, persons) and through local spread up to a specified distance. The main disease-control mechanisms that influence the disease spread in InterCSF are diagnosis of the infected farms, depopulation of infected farms, movement-control areas, tracing, and pre-emptive slaughter. InterCSF was developed using InterSpread as the basis. InterSpread was developed for foot-and-mouth disease (FMD). This paper describes the process of modifying InterSpread into InterCSF. This involved changing the assumptions and mechanisms for disease spread from FMD to CSF. In addition, CSF-specific control measures based on the standard European Union (EU) regulations were included, as well as additional control measures that were applied during the Dutch epidemic. To adapt InterCSF as closely as possible to the Dutch 1997/98 epidemic, data from the real epidemic were analysed. Both disease spread and disease-control parameters were thus specifically based on the real epidemic. In general, InterSpread turned out to be a flexible tool that could be adapted to simulate another disease with relative ease. The most difficult were the modifications necessary to mimic the real epidemic as closely as possible. The model was well able to simulate an epidemic with a similar pattern over time for number of detected farms as the real outbreak; but the absolute numbers were (despite many relevant modifications) not exactly the same--but were within an acceptable range. Furthermore, the development of InterCSF provided the researchers with a better insight into the existing knowledge gaps. In part II (see the final paper in this issue), InterCSF was used to compare various control strategies as applied to this epidemic.

Effect of hypoxia alone or combined with inflammation and 3-methylcholanthrene on hepatic cytochrome P450 in conscious rabbits

1 To investigate the effect of moderate hypoxia alone or combined with an inflammatory reaction or after 3-methylcholanthrene (3MC) pre-treatment on cytochrome P450 (P450), conscious rabbits were exposed for 24 h to a fractional concentration of inspired O2 of 10% (mean PaO2 of 34 mmHg). Hypoxia decreased theophylline metabolic clearance (ClM) from 1.73+/-0.43 to 1.48+/-0.13 ml min-1 kg-1 (P<0. 05), and reduced (P<0.05) the formation clearance of theophylline metabolites, 3-methylxanthine (3MX), 1-methyluric acid (1MU) and 1,3-dimethyluric acid (1,3DMU). Hypoxia reduced the amount of CYP1A1 and 1A2 but increased CYP3A6 proteins. 2 Turpentine-induced inflammatory reaction reduced (P<0.05) the formation clearance of 3MX, 1MU, and 1,3DMU, and diminished the amount of CYP1A1, 1A2 and 3A6 proteins. However, when combined with hypoxia, inflammation partially prevented the decrease in ClM, especially by impeding the reduction of 1,3DMU. The amount of CYP1A1 and 1A2 remained reduced but the amount of CYP3A6 protein returned to normal values. 3 Pre-treatment with 3MC augmented the ClM by 114% (P<0.05) due to the increase in the formation clearance of 3MX, 1MU and 1,3DMU. 3MC treatment increased the amount of CYP1A1 and 1A2 proteins. Pre-treatment with 3MC prevented the hypoxia-induced decrease in amount and activity of the P450. 4 It is concluded that acute moderate hypoxia and an inflammatory reaction individually reduce the amount and activity of selected apoproteins of the P450. However, the combination of hypoxia and the inflammatory reaction restores P450 activity to near normal values. On the other hand, pre-treatment with 3MC prevents the hypoxia-induced depression of the P450.

[Intrathyroid metastasis of kidney cancer. A rare case and diagnostic trap]

We report the discovery of a unique renal-cell carcinoma operated 9 years earlier on a thyroidectomy operative specimen. Intra-thyroid metastasis from kidney cancer is uncommon. The average delay to discovery as a painless thyroid nodule is estimated around 6 years following nephrectomy. Pre-operative fine needle aspiration and cytology provide the diagnosis. Prognosis of unique thyroid metastasis of kidney cancer is good despite the distant spread. Surgery is the most common therapeutic attitude.

Down-regulation of the hepatic cytochrome P450 by an acute inflammatory reaction: implication of mediators in human and animal serum and in the liver

1. Infection and inflammation trigger a cascade of mediators that eventually will down-regulate the hepatic cytochrome P450 (P450). The present study aimed to characterize the mediators contained in the serum of rabbits with an acute inflammatory reaction (AIR) induced by the s.c. injection of turpentine (5 ml), and in the serum of humans with an acute upper respiratory tract viral infection. 2. Hepatocytes from control (H(CONT)) rabbits and rabbits with an AIR (H(INFLA)) were isolated and cultured. Compared with H(CONT) in H(INFLA) the production of theophylline metabolites, 3-methylxanthine (3MX), 1-methyluric acid (1MU), and 1,3-dimethyluric acid (1,3DMU) was reduced as was the amount of total P450, while lipid peroxidation was increased. Incubation of H(INFLA) with serum of rabbits with an AIR (RS(INFLA)) for 4 h further reduced the formation of the metabolites of theophylline as well as the amount of P450, and enhanced the lipid peroxidation. RS(INFLA) obtained 6, 12 and 24 h after the injection of turpentine showed the same ability to down-regulate hepatic P450 as the serum obtained at 48 h. 3. The efficacy (Emax) of RS(INFLA) to inhibit the formation of theophylline metabolites differed, i.e. 1,3DMU > 1MU > 3MX, and the potency of serum mediators (IC50) was similar for 3MX and 1MU, but lower for 1,3DMU. 4. Incubation of serum of human volunteers (HS(INFLA)) with a viral infection with H(CONT) or H(INFLA) reduced the production of theophylline metabolites, as well as the amount of P450, and increased the lipid peroxidation. HS(INFLA) depressed 1,3DMU more efficiently than 3MX and 1MU. HS(INFLA) reduced 3MX with greater efficacy than did RS(INFLA). Potency was very variable but not different from rabbits. 5. It is concluded that the serum of rabbits with an AIR or of humans with a viral infection contain several mediators that inhibit noncompetitively various isoenzymes of the hepatic P450. The decrease in P450 induced by HS(INFLA) or RS(INFLA) is closely associated with the increase in lipid peroxidation (r2= 0.8870) suggesting that lipid peroxidation could directly or indirectly be involved in the P450 down-regulation.

First-pass metabolism of lidocaine in the anesthetized rabbit. Contribution of the small intestine

It is assumed that, in vivo, the liver is the organ responsible for the first-pass metabolism of lidocaine. To assess in vivo whether the intestine and the lungs contribute with the liver to the first-pass metabolism of lidocaine, groups of anesthetized rabbits (N = 6/group) received lidocaine into the thoracic aorta (10 mg/kg), a jugular vein (10 mg/kg), a mesenteric vein (20 mg/kg), and into the duodenum (20 mg/kg). Serial blood samples were withdrawn from the abdominal aorta. The area under lidocaine plasma concentration-time curve [AUCL(O-infinity)] corrected by the dose, when injected into the jugular vein, was equal to that estimated when injected into the thoracic aorta, but was larger than the AUCL(O-infinity) corrected by the dose of lidocaine injected into a mesenteric vein [i.e. 0.0047 +/- 0.0005 vs. 0.0030 +/- 0.0004 min/ml, respectively (p < 0.05)]. Moreover, the latter was greater (p < 0.05) than the AUCL(O-infinity) corrected by the dose of lidocaine instilled into the duodenum (0.0024 +/- 0.0003 min/ml). Liver and intestinal extractions of lidocaine were 36 and 20%, respectively. Oral systemic bioavailability was 0.49. The metabolites of lidocaine, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), were only detected when lidocaine was administered before the liver or the intestine. In in vitro studies, incubation of lidocaine in the supernatant of the 10,000g of epithelial cells of the intestine, liver, and lungs decreased lidocaine concentrations at the following rates: liver > intestine approximately lungs. MEGX and GX could be measured in the liver, but only MEGX in the small intestine and lung. It is concluded that the intestine contributes with the liver to the first-pass metabolism of lidocaine.

Lack of presystemic metabolism of nifedipine in the rabbit

In humans, oral bioavailability of nifedipine has been reported to be around 60%, although the organ(s) contributing to its first-pass metabolism have not been determined. The aim of this study was to determine in vivo, in anesthetized and conscious rabbits the role of the intestine, liver, and lungs in the first-pass metabolism of nifedipine. To assess the extraction of nifedipine by the intestine, liver, and lungs, nifedipine was administered before and after each organ, and serial blood samples were withdrawn from an artery. In conscious rabbits, the systemic clearance of nifedipine injected into a lateral vein of an ear was 14.6 +/- 1.6 ml/min per kg, a value that was slightly decreased by anesthesia. In anesthetized rabbits, compared to the clearance estimated when nifedipine was administered into the thoracic aorta, the administration of nifedipine into a jugular vein, into the portal vein, or into the portal vein, or into the duodenum did not increase the value of the systemic clearance. In conscious rabbits, the clearance of nifedipine estimated when the drug was administered into the duodenum, the peritoneum, the portal vein, or into the jugular vein was identical to the clearance calculated when the drug was injected into the thoracic aorta. In vitro, nifedipine was metabolized in liver and intestinal epithelial cells homogenates but not in lungs or kidneys. We concluded that in the rabbit, oral nifedipine is not subjected to a first-pass metabolism, even though the intestine and the liver may contribute to nifedipine systemic clearance.

[Testing area Wehl: study of risks of contacts in behalf of foot-and-mouth disease]

A study on contacts between livestock holdings was conducted in a geographically defined area of 4 by 6 km in the Netherlands. The farmers were asked to record all contact on and off farm during a period of 2 weeks. The number of contacts in the 2 week period was high, on average 91.8 contacts per farm. The risk of spreading foot-and-mouth disease on or off the farm was greater for cattle farms than for swine farms. Relatively more people had contact with the animals while visiting cattle farms, thereby causing the higher risk. Most contacts occurred over short distances. Almost 50% of the contacts were within the research area. This finding confirms the importance of restricted areas around farms with foot-and-mouth disease infections.

Extrahepatic metabolism of frusemide in anaesthetized rabbits

1. Frusemide is removed from the body by biotransformation and renal secretion, but since frusemide metabolism is not altered in patients with hepatic cirrhosis, the role of the liver may be questioned. The aim of the study was to investigate which organs contribute to the first-pass metabolism and systemic clearance of frusemide. 2. Groups of anaesthetized New Zealand rabbits were administered frusemide proximally (prox) and distally (dist) to different organs, and blood was sampled from the abdominal aorta. The area under frusemide plasma concentrations-time curve (AUC0-infinity) was calculated and frusemide extraction by an organ was estimated from the ratio (AUCdist-AUCprox)/AUCdist. The small intestine extracted 83% of the absorbed dose of frusemide but the first-pass uptake by the liver and lungs was negligible. 3. To assess the contribution of the intestine and the kidneys to the systemic clearance of frusemide, it was injected into the jugular vein and blood was sampled proximal and distal to each organ. The kidneys extracted 24% of frusemide circulating in the renal arteries; on the other hand, the ability of the intestine to extract frusemide from the systemic circulation could not be detected. 4. The lungs did not metabolize frusemide in vitro; the rate of metabolism of frusemide in vitro by kidneys was similar to that estimated in the intestine, and both rates were faster (P < 0.05) than that observed in the liver. 5. It is concluded that in rabbits, presystemic metabolism of frusemide is carried out by the intestine, and that systemic clearance of frusemide is mainly performed by the kidneys, although other organs, such as the intestine and the liver, must contribute to it.

Contribution of the small intestine to the first-pass uptake and systemic clearance of propranolol in rabbits

Epithelial cells of the intestine enclose isozymes able to metabolize propranolol, raising the possibility that the gut contributes with the liver to the first-pass uptake and systemic clearance of propranolol. To assess the role of the liver in the first-pass uptake, propranolol was injected into the jugular vein and a mesenteric vein of anesthetized New Zealand rabbits, and blood samples were drawn from the abdominal aorta, or it was injected into the intestine and samples were drawn simultaneously from the portal vein and the abdominal aorta. Extraction of propranolol by the liver was estimated to be 96-97%. To assess the intestinal extraction of oral propranolol, a porto-cava transposition was conducted in two groups of animals, and propranolol was injected into the first 30 cm of the small intestine or into the jugular vein and samples were withdrawn from the abdominal aorta; propranolol extraction by the intestine was 43%. To document the contribution of the intestine in the systemic clearance of propranolol, propranolol was injected into the jugular vein and blood samples were drawn simultaneously from the abdominal aorta (before the gut) and from the portal vein (after the gut); propranolol extraction from the systemic circulation by the intestine was 24%. Only the liver generated detectable amounts of conjugated metabolites of propranolol. In the in vitro studies, it was shown that propranolol was rapidly metabolized by the liver, yielding 4-hydroxypropranolol and conjugates of propranolol; propranolol metabolism in the proximal small intestine was slower and yielded only 4-hydroxypropranolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Technetium-99m hydroxymethylene diphosphonate scanning of acute injuries to the lateral ligaments of the ankle

Technetium-99m hydroxymethylene diphosphonate scans were performed on 29 consecutive patients with acute ankle ligament injuries. Scanning reliably differentiated a severe from a minor injury. Severe injuries gave a diffuse uptake on the scan and the minor injuries a more localized increase in uptake.

Synovial chondromatosis

We reviewed 53 cases of synovial chondromatosis and compared their clinical, radiological and pathological features. A radiological diagnosis is possible with increasing frequency as the disease progresses; in the early phase arthrography is helpful. Radiologically the disease may be classified as either extra-articular, or intra-articular; the intra-articular variety may be localised or generalised. Recurrence after operation was seen in 11.5% and was much the same after either synovectomy or simple removal of loose bodies. A protocol for treatment is proposed.