Animal Health Modeling & Simulation Society: a new society promoting model-based approaches in veterinary pharmacology.

The Animal Health Modeling & Simulation Society (AHM&S) is a newly founded association (2012) that aims to promote the development, application, and dissemination of modeling and simulation techniques in the field of Veterinary Pharmacology and Toxicology. The association is co-chaired by Pr. Johan Gabrielsson (Europe), Pr. Jim Riviere (USA), and secretary Dr. Jonathan Mochel (Switzerland). This short communication aims at presenting the membership, rationale and objectives of this group.

A case of multifocal chronic Q fever osteomyelitis.

Chronic Q fever can be difficult to diagnose because of a variety of non-specific clinical presentations. Chronic Q fever osteoarticular infections have rarely been reported in the literature. We describe here an unusual multifocal osteomyelitis due to Coxiella burnetii in an adult.

Outcome of exfoliative rejection after isolated intestinal transplantation in an adult: case report.

A 34-year-old-man with short-bowel syndrome received an isolated small bowel graft. On postoperative day (POD) 11, ileal biopsy specimen demonstrated mild to moderate rejection that did not respond to corticosteroid bolus therapy. On POD 14, endoscopy and histologic examination revealed exfoliative rejection that was not controlled after 14 days of therapy with thymoglobulin. On POD 95, the patient underwent surgery again because of intestinal obstruction. The graft was removed 6 months after transplantation because of continuous severe abdominal pain with weight loss. After enterectomy, the patient developed multiple-organ failure and died on POD day 8. This case underlines the severity of exfoliative rejection and suggests that early enterectomy be performed when the diagnosis is made, before deterioration of clinical status and development of infectious and nutritional complications.

Overview of model-building strategies in population PK/PD analyses: 2002-2004 literature survey.

AIMS: A descriptive survey of published population pharmacokinetic and/or pharmacodynamic (PK/PD) analyses from 2002 to 2004 was conducted and an evaluation made of how model building was performed and reported. METHODS: We selected 324 articles in Pubmed using defined keywords. A data abstraction form (DAF) was then built comprising two parts: general characteristics including article identification, context of the analysis, description of clinical studies from which the data arose, and model building, including description of the processes of modelling. The papers were examined by two readers, who extracted the relevant information and transmitted it directly to a MySQL database, from which descriptive statistical analysis was performed. RESULTS: Most published papers concerned patients with severe pathology and therapeutic classes suffering from narrow therapeutic index and/or high PK/PD variability. Most of the time, modelling was performed for descriptive purposes, with rich rather than sparse data and using NONMEM software. PK and PD models were rarely complex (one or two compartments for PK; E(max) for PD models). Covariate testing was frequently performed and essentially based on the likelihood ratio test. Based on a minimal list of items that should systematically be found in a population PK-PD analysis, it was found that only 39% and 8.5% of the PK and PD analyses, respectively, published from 2002 to 2004 provided sufficient detail to support the model-building methodology. CONCLUSIONS: This survey allowed an efficient description of recent published population analyses, but also revealed deficiencies in reporting information on model building.

Changing of hepatitis C virus genotype patterns in France at the beginning of the third millenium: The GEMHEP GenoCII Study.

This cross-sectional study aimed to investigate, during a short period between 2000 and 2001, in a large population of patients with chronic hepatitis C, the epidemiological characteristics of hepatitis C virus (HCV) genotypes in France. Data from 26 referral centres, corresponding to 1769 patients with chronic hepatitis C were collected consecutively during a 6-month period. HCV genotyping in the 5'-non-coding region (NCR) was performed in each center using the line probe assay (LiPA, in 63% of cases), sequencing (25%) or primer-specific polymerase chain reaction (PCR) (12%). HCV genotypes 1a, 1b, 2, 3, 4, 5, non-subtyped 1 and mixed infection were found in 18, 27, 9, 21, 9, 3, 11 and 1% of our population, respectively. HCV genotype distribution was associated with gender, age, source and duration of infection, alanine aminotransferase (ALT) levels, cirrhosis, alcohol consumption, hepatitis B virus (HBV) and human immunodeficiency virus (HIV) coinfection. In multivariate analysis, only the source of infection was the independent factor significantly associated with genotype (P = 0.0001). In conclusion, this study shows a changing pattern of HCV genotypes in France, with i.v. drug abuse as the major risk factor, an increase of genotype 4, and to a lesser extent 1a and 5, and a decrease of genotypes 1b and 2. The modification of the HCV genotype pattern in France in the next 10 years may require new therapeutic strategies, and further survey studies.

Gentamicin nephrotoxicity--a comparison of in vitro findings with in vivo experiments in equines.

The aminoglycoside gentamicin is often used in equine practice. Despite its clinical use, concerns remain regarding the potential toxic side-effects, such as nephrotoxicity, in equine patients, particularly after repeated dosing. The aim of the study was to investigate first in vitro the mechanisms contributing to the renal toxicity of gentamicin and to identify sensitive biomarkers indicating proximal tubule damage. To this end, the kidney-derived cell lines LLC-PKI and MDCK were treated with gentamicin at different concentrations. Toxicity was assessed by measuring the release of gamma-glutamyl transferase (GGT), and the production of reactive oxygen species (ROS). Cell viability was measured using Alamar blue (AB) and Neutral red (NR) cytotoxicity assays. Gentamicin exerted a dose-dependent toxicity. Primarily, loss of brush border membrane integrity, indicated by GGT leakage, and an increased ROS production were observed. As GGT was found to be a sensitive marker for gentamicin-induced renal cell injury, in the subsequent in vivo experiments, in which ponies were given gentamicin (3.0 mg/kg bw three times daily and 4.5 mg/kg bw twice daily) for five consecutive days, plasma levels and the urinary excretion of GGT and creatinine were measured and the GGT:creatinine ratio was calculated. Elevated GGT levels in urine following gentamicin therapy were observed, but this enzyme leakage was transient and returned to baseline values after cessation of therapy. It could thus be concluded that even a conservative dose regimen of gentamicin did not result in significant renal toxicity in healthy ponies.

Influence of fluid therapy on gentamicin pharmacokinetics in colic horses.

The aminoglycoside antibiotic gentamicin is commonly used in equine medicine for the prevention and treatment of Gram-negative and staphylococcal bacteria in surgically treated colic patients. The pharmacokinetics of gentamicin in these patients might be altered by the disease status, and/or under the influence of fluid therapy. The purpose of this study was to investigate the effect of intravenous fluid treatment on gentamicin kinetics in colic patients. Colic patients subjected to laparotomy were given fluid infusions according to clinical status. Following gentamicin administration, blood samples were taken for gentamicin analysis at different time points, and the main pharmacokinetic parameters including Vc, Vss, t(1/2) and MRT were calculated. Horses undergoing fluid therapy showed a significantly different t(1/2), clearance and MRT as compared to non-infused patients. However, taking into account the clinical status of the patients receiving fluid support, the data suggest that endotoxaemia, rather than fluid therapy, influence gentamicin pharmacokinetics following laparotomy.

The severity of liver fibrosis is associated with high leptin levels in chronic hepatitis C.

Recent attention has focused on the liver profibrogenic role of leptin in animal models. The purpose of this study was to evaluate the role of leptin and TNF-alpha in the severity of liver fibrosis in patients with chronic hepatitis C (CHC). We used a radioimmunoassay to determine serum leptin concentrations in 77 consecutive patients with CHC and 22 healthy controls. Leptin was correlated with liver histological (METAVIR) and metabolic indices. Sixty five patients had none to moderate liver fibrosis (F0-F2) and twelve severe fibrosis (F3-F4). Steatosis was observed in all but 27 patients. Leptin was significantly increased in patients compared with controls and was significantly more elevated in females both in patients and controls. The age, age at infection, prothrombin index, body mass index (BMI), triglycerides, glycaemia, ferritin, leptin and TNF-alpha, were associated with severe fibrosis. Steatosis was significantly more pronounced in patients with severe than those without or moderate fibrosis (P = 0.04). Only leptin was significantly and independently associated with severe fibrosis (OR = 1.2, CI 95%: 1.1-1.4, P = 0.03). Leptin was significantly associated with BMI (r = 0.64, P < 0.001) and glycaemia (r = 0.43, P < 0.001). Significant correlations were found between steatosis and BMI (r = 0.30, P < 0.01) and glycaemia (r = 0.30, P < 0.01). In patients with CHC and higher BMI and glycaemia levels, the severity of liver fibrosis is associated with serum leptin. TNF-alpha is a putative candidate involved in the mechanism.

Modelling the loss of metabolic capacities of cultured hepatocytes: application to measurement of Michaelis-Menten kinetic parameters in in vitro systems.

1. The loss of metabolic capacities during culture time constitutes a major limitation for the use of hepatocyte primary cultures in in vitro metabolism measurements. A new strategy is presented that permits one to calculate the Michaelis-Menten parameters V(max) and K(m) from extended experiments, by modelling V(max) as a variable dependent on time using exponential or sigmoidal equations. 2. This method was tested with cortisol depletion in cultured rat hepatocytes. V(max) and K(m) were used to calculate intrinsic clearance, and comparisons were made with methods already described in the literature. Intrinsic clearances given by our method were scaled to in vivo hepatic clearances that were close to those reported in the literature. 3. Our method could quantify the V(max) decrease with culture time from estimates of time parameters, t(1/2) or t(50). In our system, this V(max) decrease was in agreement with P450 cytochrome inactivation rates published for the rat liver. 4. In conclusion, we propose a convenient, simple and useful general method for both Michaelis-Menten parameter estimation and modelling of variations in the metabolic capacities observed in in vitro systems. Such an approach should improve the usefulness of hepatocytes in primary cultures for long-term metabolism experiments.

Fatigue is associated with high circulating leptin levels in chronic hepatitis C.

BACKGROUND AND AIMS: Fatigue is a frequent and disabling symptom reported by patients with chronic hepatitis C (CHC). Its mechanism is poorly understood. Recent attention has focused on the role of leptin and energy expenditure in CHC. Our aims were to analyse fatigue in CHC and to determine its relationship with disease activity, resting energy expenditure (REE), circulating leptin, and tumour necrosis factor alpha (TNF-alpha). METHODS: Seventy eight CHC patients, 22 healthy controls, and 13 primary biliary cirrhosis (PBC) patients underwent measurements of REE, body composition, leptin, and TNF-alpha. All subjects completed the fatigue impact scale (FIS) questionnaire. A liver biopsy and viral load measurements were performed in all patients. RESULTS: Thirty eight of 78 CHC patients considered fatigue the worst or initial symptom of their disease. The fatigue score of patients was significantly higher than that of controls (53.2 (40.1) v 17.7 (16.9); p<0.0001) and was more pronounced in females (p=0.003). Leptin was increased significantly in CHC patients compared with controls (15.4 (20.7) v 6.4 (4.1) ng/ml; p<0.05). In CHC patients, the fatigue score correlated significantly with leptin corrected for fat mass (r=0.30, p=0.01). This correlation increased when the physical domain of fatigue was included (r=0.39, p=0.0009). Furthermore, a similar positive correlation was found in PBC patients (r=0.56, p=0.04). No correlation was found between fatigue and age, REE, liver function tests, viral load, or the METAVIR score in CHC patients. CONCLUSIONS: Fatigue is present in CHC patients and is more pronounced in females. The FIS questionnaire is clinically relevant and may be useful for future therapeutic trials aimed at reducing fatigue. Fatigue may be partly mediated by leptin.

Licking behaviour and environmental contamination arising from pour-on ivermectin for cattle.

Pour-on formulations of endectocides are extensively used to treat and control systemic parasitic diseases in cattle, worldwide. The purpose of the present study was to investigate the influence of the natural licking behaviour of cattle on the plasma and faecal disposition of topically administered ivermectin. Twelve Holstein cattle were given one single intravenous (i.v.) (200 microg/kg) and topical (500 microg/kg) administration of ivermectin at a 5-month interval. For the pour-on administration, the animals were allocated into two groups (n=6): one control group (lickers) and one group where licking was prevented (non-lickers). Ivermectin plasma (total) clearance (270+/-57.4 ml/kg/day) was very homogeneous among the 12 cattle. In contrast, major differences between lickers and non-lickers were observed following pour-on administration. Prevention of licking resulted in an extended terminal plasma half-life (363+/-16.2 vs. 154+/-7.4 h in lickers) and in a lower and less variable systemic availability of ivermectin (19+/-4.9 vs. 33+/-18.5% in lickers). More importantly, nearly 70% of the pour-on dose was recovered as parent drug in the faeces of lickers vs. only 6.6% in non-lickers. Altogether, these results are consistent with an oral rather than percutaneous absorption of topical ivermectin in control animals, the non-systemically available fraction of ingested ivermectin providing a major contribution (80%) to the drug faecal output. The consequences of licking on the disposition of pour-on ivermectin are discussed in terms of environment, given the known ecotoxicity of this drug, and of cross-contamination. Animals licking themselves and each other could result in unexpected residues in edible tissues of untreated animals and in possible subtherapeutic drug concentrations, a factor in drug resistance. According to the Precautionary Principle, these considerations elicit concern over the use of topical drug formulations in cattle.

Effects of 1-year interferon-alpha 2a treatment in patients with chronic hepatitis C and persistently normal transaminase activity.

BACKGROUND: Certain chronic hepatitis C carriers have persistently normal transaminase activity. The aims of this study were to determine the virologic and histologic effects of 1 year of interferon-alpha treatment in such patients. METHODS: Thirty-one patients were followed up in our Liver Unit. Eleven accepted interferon-alpha therapy; the 20 others were not treated and served as controls. Interferon-alpha, 3 MU, was given thrice weekly for 1 year. Serum was examined for hepatitis C virus (HCV)-RNA before, at the end of, and 6 months after treatment. Liver biopsy was performed 6 months after the cessation of treatment in 10 of 11 treated patients (one refused biopsy) and after a mean of 30.6+/-22.7 months in the 20 untreated patients. RESULTS: At the end of follow-up two of the treated patients had undetectable serum HCV-RNA and five had increased alanine aminotransferase (ALAT) values. In contrast, only one of the untreated patients had abnormal ALAT activity. All 20 untreated patients were constantly viremic. No significant histologic improvement was observed in the treated patients evaluated by means of post-treatment liver biopsy. The mean annual progression rate of fibrosis was very slow and similar in the treated and untreated patients (0.09 (range, 0-0.62) versus 0.07 (range, 0-0.60) fibrosis units). CONCLUSIONS: One year of interferon-alpha treatment can suppress HCV-RNA in patients with chronic hepatitis C and persistently normal ALAT values followed up over long periods. The rate of fibrosis progression in such patients is very slow, and therapeutic strategies should take this fact into account. Antiviral treatment is debated for patients without fibrosis in initial biopsy specimens.

Second generation of the automated Cobas Amplicor HCV assay improves sensitivity of hepatitis C virus RNA detection and yields results that are more clinically relevant.

The first and second generations of the Cobas Amplicor HCV assay were compared among patients at risk of hepatitis C virus (HCV) infection. The second-generation test was found to be of greater sensitivity and of good specificity among clinical specimens containing HCV RNA of different genotypes. Finally, this new test is shown to predict the outcome of interferon therapy better.

Rapid genotyping of hepatitis C virus by direct cycle sequencing of PCR-amplified cDNAs and capillary electrophoresis analysis.

There is an increasing demand for the genotyping of hepatitis C virus (HCV), since it has been shown that different HCV genotypes are associated with distinct profiles of pathogenicity and responses to antiviral treatment. Hence, there is a need for a simple and precise genotyping assay for routine diagnosis of HCV types and subtypes. Here we show that direct sequencing, considered as the reference method, can provide an accurate and rapid method for large-scale screening of HCV genotypes. PCR-amplified cDNAs of the HCV 5' non-coding region (5' NCR) were obtained from the widespread "Amplicor" HCV detection system. Semi-purified PCR products were directly cycle-sequenced in a single tube using multicolour dye terminator chemistry. Sample loading, electrophoresis and sequence analysis were automatically achieved by a capillary electrophoresis-based genetic analyser. Out of a total of 500 samples, HCV subtype 1b accounted for the majority of the infections (41%), followed by HCV 3 (31%) and HCV 1a (22%). This procedure failed to identify a genotype in only 3 samples. In addition, several cases of mixed HCV infection were also documented. The combination of direct cycle sequencing of PCR products with capillary electrophoresis provides a simple and rapid method convenient for routine HCV genotyping analysis.

Hepatitis G and C viruses respond to interferon-alpha with different virologic kinetics.

The aim of this work was to specify the time course of response to interferon (IFN) of hepatitis G virus (HGV) and hepatitis C virus (HCV) in coinfected individuals. A group of 33 patients, undergoing 12 months of IFN therapy for chronic hepatitis C, was screened for the presence of both HGV and HCV RNAs to select seven coinfected patients. Spontaneous recovery from HGV infection was excluded through the detection of antibodies to the envelope-2 protein of HGV and HCV isolates were genotyped. Within three months of treatment, we found that HGV RNA was transiently cleared in 6/7 patients, but the rate of long-term favorable response was very low (1/7). In addition, considering the same individuals separately, it was shown that HGV and HCV responded to IFN with different kinetics in 5/7 patients. Taken together, these results underscore the importance of the virological basis of the resistance to IFN treatment.

Cloning and expression of cDNA for a human Gal(beta1-3)GalNAc alpha2,3-sialyltransferase from the CEM T-cell line.

Complementary DNA encoding a human Gal(beta1-3)GalNAc alpha2,3-sialyltransferase type II (hST3Gal II) was cloned from a CEM T-cell cDNA library using a 23-base oligonucleotide probe. The sequence of this probe was established on the basis of a slightly divergent sialylmotif L that was obtained by polymerase chain reaction with degenerate oligonucleotide primers based on the conserved sialylmotif L of mammalian Gal(beta1-3)GalNAc alpha2,3-sialyltransferases. It was thus confirmed that a short oligonucleotide probe may be sensitive and highly specific. The nucleotide and amino acid sequences of hST3Gal II show, respectively, 56.3% and 49.3% similarity to hST3Gal I [Kitagawa, H. & Paulson, J. C. (1994) J. Biol. Chem. 269, 17872-17878] and 88.1% and 93.7% similarity to murine ST3Gal II [Lee, Y. C., Kojima, N., Wada, E., Kurosawa, N., Nakaoka, T., Hamamoto, T. & Tsuji, S. (1994) J. Biol. Chem. 269, 10028-10033]. hST3Gal II mRNA was highly expressed in heart, liver, skeletal muscle and various lymphoid tissues but not in brain and kidney. A soluble form of hST3Gal II expressed in COS-7 cells was tested in vitro for substrate specificity and kinetic properties. Asialofetuin and asialo-bovine submaxillary mucin appeared better substrates for hST3Gal II than for its murine counterpart as previously reported [Kojima, N., Lee, Y.-C., Hamamoto, T., Kurosawa, N. & Tsuji, S. (1994) Biochemistry 33, 5772-5776]. In previous studies, we have shown hyposialylation of O-glycans attached to two major lymphocyte CD43 and CD45 cell surface molecules in human-immunodeficiency-virus-1(HIV-1)-infected T-cell lines. Since comparable levels of hST3Gal I and hST3Gal II mRNA and enzymatic activity were observed in parental and HIV-1-infected CEM T-cell lysates, the sialylation defect associated with HIV infection of this cell line is probably due to a mechanism different from a simple altered catalytic activity of these sialyltransferases.

Phenotyping of intrahepatic and peripheral blood lymphocytes in patients with chronic hepatitis C.

The host immune responses have been suggested to play a role in liver injury occurring in patients with chronic hepatitis C. In order to explore the relationship between the relative proportions of intrahepatic and peripheral blood lymphocytes (IHL, PBL), the levels of viremia, and the histological hepatitis activity score, three-color fluorescence-activated cytometric analysis was performed for 36 patients with chronic hepatitis C and six control subjects without chronic hepatitis. The liver biopsy was performed before any antiviral therapy. Each liver specimen was divided into two parts: one for histological examination and one for immunological analysis. Tricolor CD45 was used to improve "lymphogating." Fluorescein isothiocyanate- or phycoerythrin-conjugated monoclonal antibodies with specificity for CD3, CD4, CD8, and CD20 (lymphocyte subpopulations), for CD69 (activated lymphocytes), and for CD16/56 (natural killer cells) were used. The livers of patients with chronic hepatitis C contained a greater proportion of CD4+ lymphocytes that exhibited marked expression of CD69 than in control subjects (20.7 +/- 7.3% vs 10.2 +/- 4.6%, P = 0.027). Moreover, in patients with chronic hepatitis C, the proportion of CD4+ IHL correlated with the histological hepatitis activity evaluated by the Knodell score (r = 0.48, P = 0.004). No correlation was found between the percentage of CD4+ IHL and the level of viremia or transaminase activities. Our findings clearly indicate that a cellular immune response does take place in HCV-infected livers and could thus contribute to the outcome of hepatitis C virus infection.

Guillain-Barré syndrome associated with acute Q fever.

Several bacterial and viral agents have been implicated in the pathogenesis of the Guillain-Barré syndrome, an acquired immune-mediated disorder. A case of Guillain-Barré syndrome associated with acute Q fever is described. Coxiella burnetii should therefore be added to the list of microorganisms capable of inducing the Guillain-Barré syndrome.