Towards eradication of bovine tuberculosis in the European Union.

This paper reviews the developments and progress towards eradication of bovine tuberculosis in the European Union (EU). A historical view of the EU legislation aimed at mainly approximating provisions on intra-community in cattle trade explains the present EU policies. The variety of cattle breeding systems and environmental conditions in the EU leads to different epidemiological situations. The current situation of bovine tuberculosis in the EU Member States is summarised, and current policy in the EU is outlined.

Detection of polychlorinated biphenyls and dioxins in Belgian cattle and estimation of the maximal potential exposure in humans through diets of bovine origin.

The methodology used to detect a polychlorinated biphenyl (PCB)/dioxin contamination in a Belgian cattle population that was not exposed to the PCB/dioxin incident in 1999 is presented. This population is directly or indirectly destined for human consumption. The methodology consisted in the systematic sampling of all calf-fattening stations and groups of cattle destined for export, and in the random sampling of slaughter cattle. This approach is compared to the method described in directive 96/23/CE from the European Council. When PCB concentrations exceeded the tolerance level of 0.2 micro g/g body fat (seven congeners with numbers 28, 52, 101, 118, 138, 153, and 180), dioxins (seventeen 2,3,7,8-substituted congeners of PCDD and PCDF) were also determined. The prevalence of Belgian slaughter cattle with PCB concentrations above this cutoff was 0.3% (95% confidence interval: 0.01-1.50%). Results indicate that the incidence of contamination was minimal, with environmental origin and common in all industrial countries. The maximal potential exposure of an adult human consumer to dioxins through diet of bovine origin is estimated in two worst-case scenarios. The first one corresponds to the consumption of contaminated food products by a small number of consumers during a long period (local consumption) and the second simulates the consumption of contaminated products by a large number of consumers during a short period (supermarket purchase). The theoretical maximum daily intake of dioxins in adults was respectively 374 and 123 pg TEQ/d. The estimated maximum increase of dioxin body burden corresponds to 7 pg TEQ/g fat in the local consumption scheme and 0.07 pg TEQ/g fat in the supermarket consumption scheme.

Prevalence of paratuberculosis (Johne's disease) in the Belgian cattle population.

The national bovine paratuberculosis (PTB) seroprevalence (apparent prevalence) in the Belgian cattle population was determined by a serological survey that was conducted from December 1997 to March 1998. In a random sample of herds (N=556, 9.5%), all adult cattle of 24 months of age or older (N=13,317, 0.4%) were tested for the presence of antibodies using a commercially available absorbed ELISA test kit. The PTB median within-herd seroprevalence (proportion of detected animals within the seropositive herds) and the PTB individual-animal seroprevalence (proportion of detected animals) were, respectively, 2.9% (quartiles=1.6-5.6) and 0.87% (95% confidence interval (CI)=0.71-1.03). The PTB herd seroprevalence (proportion of detected herds) was 18% (95% CI=14-21). Assuming a test sensitivity and specificity of 45 and 99% [Sweeney et al., 1995. J. Vet. Diagn. Invest. 7 (4), 488; Sockett et al., 1992. J. Clin. Microbiol. 30 (5), 1134], respectively, the median true within-herd prevalence and the true individual-animal were estimated to be 7 and 2%, respectively. The true herd prevalence of Mycobacterium paratuberculosis infection was first estimated according to currently accepted methodology. This calculation revealed that the specificity of the used test has a dramatic effect on the estimation; assuming a test sensitivity of 45% and a true within-herd prevalence of 7%, the true herd prevalence estimation decreased from 36 to 0.8% if the test specificity decreased from 99. 9 to 99%, respectively. This sensitivity analysis showed that the practical limits of the accuracy of the used screening test jeopardize the estimation of the true herd prevalence within reasonable confidence limits, because the within-herd PTB true prevalence was low. For this reason we augmented the herd specificity for herds with larger adult herd size (>5). This was done by increasing the cut-off number of positive cattle required (>/=2) to classify a herd truly positive and including herds with one positive test result if there was historical evidence of PTB (previous diagnosis and/or clinical signs). This approach resulted in an estimated true herd prevalence of M. paratuberculosis infection of 6%. The true herd prevalence for dairy, mixed and beef herds was, respectively, 10, 11 and 3%.

Prevalence of bovine herpesvirus-1 in the Belgian cattle population.

The national bovine herpesvirus 1 (BHV-1) seroprevalence (apparent prevalence) in the Belgian cattle population was determined by a serological survey that was conducted from December 1997 to March 1998. In a random sample of herds (N=556), all cattle (N=28478) were tested for the presence of antibodies to glycoprotein B of BHV-1. No differentiation could be made between vaccinated and infected animals, because the exclusive use of marker vaccines was imposed by law only in 1997 by the Belgian Veterinary Authorities. Twenty-one percent of the farmers vaccinated continuously against BHV-1. In the unvaccinated group, the overall herd, individual-animal and median within-herd seroprevalences were estimated to be 67% (95% confidence interval (CI)=62-72), 35.9% (95% CI=35.0-36.8) and 33% (quartiles=14-62), respectively. Assuming a test sensitivity and specificity of 99 and 99.7%, respectively, the true herd, individual-animal and median within-herd prevalence for the unvaccinated group of herds were estimated to be 65, 36 and 34%, respectively. The true herd prevalence for dairy, mixed and beef herds were respectively, 84, 89 and 53%; the true individual-animal prevalence for those types of herds were, respectively, 35, 43 and 31%; whereas, the true median within-herd prevalences were 36, 29 and 38%.

An experimental infection with a classical swine fever virus in weaner pigs. II. The use of serological data to estimate the day of virus introduction in natural outbreaks.

In a companion paper a logistic regression model of seroprevalence over time was developed on the basis of data obtained during an experimental infection of weaner pigs with classical swine fever (CSF) virus. The model was applied to seroprevalence data from three outbreaks of the 1993-1994 epizootic to test whether the model could predict correctly the day of virus introduction into the herd. It was concluded that the logistic regression model has potential as a tool to estimate in retrospect the day CSF virus was introduced into a pig herd, which in turn may assist in identification of risk factors implicated in the further spread of the disease.

Epidemiological characteristics of an outbreak of classical swine fever in an area of high pig density.

The objective of this study was to analyse an outbreak of classical swine fever under a policy of non-vaccination, intensive surveillance and eradication in an area of high pig density. The virus was found in 52 herds, where some 90,000 pigs were slaughtered. The clinical signs were vague and the reports of suspect herds generally coincided with increased mortality. The interval between the first occurrence of clinical signs and the report of a suspect herd was shorter when the disease was first diagnosed in fattening pigs than when it was diagnosed in sows, boars or suckling piglets. Among fattening pigs, mortality and morbidity appeared to increase with age. The proportion of clinically ill animals was positively correlated with the proportion of serologically positive animals in a pig house during the phase when the disease was spreading. Fifty-eight per cent of pig houses containing only clinically healthy but some virologically positive pigs were serologically negative. Antigen detection was therefore critical for early disease detection. Serology was nevertheless useful to ascertain that swine fever was not endemic in the area. The secondary cases were concentrated in the close neighbourhood of the herd initially infected.

The role of T cells in rheumatoid arthritis.

The most striking arguments in favor of a T cell dependent nature of RA are the strong association of the disease with selected class II HLA haplotypes (the "shared epitope" hypothesis) and the fact that, in experimental animal models such as adjuvant arthritis, the disease can be transferred by isolated T cell lines. It is true that T cell activation at the site of inflammation is not excessive. However, there is now unequivocal evidence for focal synthesis of IL-2 and IFN-gamma in the RA synovial membrane and one may realise that a limited but specific T cell activation may be sufficient to induce or perpetuate the immune process. This same argument may explain the lack of clear TCR restriction at the sites of inflammation. Until now, no antigen has been demonstrated to initiate and/or perpetuate RA. Different antigens though have been incriminated in the pathogenesis of RA, including cartilage antigens (collagen, proteoglycans, chondrocyte antigens), heat shock proteins or exogenous (viral/bacterial) antigens. Unless one can pick up the right antigen and clone the relevant T cells, it will be very hard to directly prove a T cell-dependent nature of the disease.

T cell receptor V beta usage in rheumatoid nodules: marked oligoclonality among IL-2 expanded lymphocytes.

Rheumatoid arthritis is an autoimmune disease which is characterized by chronic polyarthritis and joint destruction as well as by extra-articular manifestations, typically including the appearance of rheumatoid nodules. Although the pathogenesis of the disease is unknown, substantial evidence suggests that it is T cell-mediated. In contrast to experimental models, the disease-mediating T cells in the human situation have never been isolated or identified. We expanded T lymphocytes from human rheumatoid nodules by IL-2 stimulation and observed a marked oligoclonality among these expanded lymphocytes. This tendency towards oligoclonality was not seen in IL-2-expanded lymphocytes from peripheral blood. We hypothesize that this oligoclonal expansion reflects a clonally restricted in situ preactivation of lymphocytes and that precisely these preactivated cells are involved in the pathogenesis of the rheumatic process.

Mg2+, Asp-, and Glu--effects in the processive and distributive DNA relaxation catalyzed by a eukaryotic topoisomerase.

The salt requirement for the catalysis of DNA relaxation carried out by a eukaryotic DNA topoisomerase I from Candida was reexamined with plasmid pBR322 DNA. Two levels of analysis were considered: the initial velocity of the overall reaction and the mode of this reaction (processivity vs distributivity). When looking at the monovalent salts from the first level, the replacement of Cl- by Glu- or Asp- greatly enhanced the salt range over which the enzyme was active. Moreover, the initial velocity reached an optimal value for a higher salt concentration in this case. For the cationic counterpart, K+ was a little more effective than Na+ and much more so than NH4+. Addition of 4 mM magnesium chloride affected both the range and the optimum of the initial velocity differentially, depending upon the monovalent salt, but with a general stimulating tendency. On the other hand, when the Mg2+ salt was varied, substitution of chloride by aspartate enhanced the optimum of the initial velocity for a fixed KCl concentration. In addition, magnesium aspartate (MgAsp2) and magnesium glutamate (MgGlu2) allowed the reaction to occur even without monovalent salt and over an extended range. Magnesium was also shown to directly interact with the general catalysis (Kd = 2.5 mM). From the second level of analysis, the presence of Mg2+ (except with NH4Glu), the substitution of Cl- by Glu- or Asp-, and a lower monovalent salt concentration than that used for the velocity optimum were required to promote the processive mode.(ABSTRACT TRUNCATED AT 250 WORDS)

Lysine degradation in Candida. Characterization and probable role of L-norleucine-leucine, 4-aminobutyrate and delta-aminovalerate:2-oxoglutarate aminotransferases.

Three enzymes partially purified that catalyze respectively the transamination of L-norleucine, 4-aminobutyrate and delta-aminovalerate with alpha-ketoglutarate as aminoacceptor were characterized and isolated from L-lysine adapted cell of Candida guilliermondii var. membranaefaciens. The transaminases have a maximum activity in the pH range of 7.8-8.5 and at 55 degrees C, 45 degrees C and 40 degrees C respectively. alpha-Ketoglutarate and to a lesser extent pyridoxal-5'-phosphate were effective protecting agents against rise in temperature. The enzymes exhibit absorption maximum at 280 nm, 330 nm and 410 nm. The fact that L-norleucine-leucine aminotransferase, 4-aminobutyrate aminotransferase and delta-aminovalerate aminotransferase are strongly induced by growing the yeast Candida on L-lysine suggests new hypothetic pathways for the catabolism of L-lysine where the main substrate of each aminotransferase could be an intermediary metabolite.

Candida L-norleucine,leucine:2-oxoglutarate aminotransferase. Purification and properties.

A new enzyme which catalyzes the transamination of L-norleucine (2-aminohexanoic acid) and L-leucine with 2-oxoglutarate was purified to homogeneity from cells of Candida guilliermondii var. membranaefaciens. The relative molecular mass determined by gel filtration was estimated to be close to 100,000. The transaminase behaved as a dimer which consists of two subunits identical in molecular mass (Mr 51,000). The enzyme has a maximum activity in the pH range of 8.0-8.5 and at 55 degrees C. 2-Oxoglutarate, and to a lesser extent pyridoxal 5'-phosphate, were effective protecting agents against increasing temperature. The enzyme exhibits absorption maximum at 330 nm and 410 nm. L-Norleucine, and L-leucine to a lesser extent, are the best amino donors with 2-oxoglutarate as amino acceptor. The Km values for L-norleucine, L-leucine and 2-oxoglutarate determined from the Lineweaver-Burk plot were 1.8 mM, 6.6 mM and 2.0 mM respectively. A ping-pong bi-bi mechanism of inhibition with alternative substrates is found when the enzyme is in the presence of both L-norleucine and L-leucine. The inhibitory effect of various amino acid analogs on the transamination reaction between L-norleucine and 2-oxoglutarate was studied and Ki values were determined.

4-Aminobutyrate:2-oxoglutarate aminotransferase from Candida. Purification and properties.

An enzyme which catalyzes the transamination of 4-aminobutyrate with 2-oxoglutarate was purified 588-fold to homogeneity from Candida guilliermondii var. membranaefaciens, grown with 4-aminobutyrate as sole source of nitrogen. An apparent relative molecular mass of 107,000 was estimated by gel filtration. The enzyme was found to be a dimer made up of two subunits identical in molecular mass (Mr 55,000). The enzyme has a maximum activity in the pH range 7.8-8.0 and a temperature optimum of 45 degrees C. 2-Oxoglutarate protects the enzyme from heat inactivation better than pyridoxal 5'-phosphate. The absorption spectrum of the enzyme exhibits two maxima at 412 nm and 330 nm. The purified enzyme catalyzes the transamination of omega-amino acids; 4-aminobutyrate is the best amino donor and low activity is observed with beta-alanine. The Michaelis constants are 1.5 mM for 2-oxoglutarate and 2.3 mM for 4-aminobutyrate. Several amino acids, such as alpha,beta-alanine and 2-aminobutyrate, are inhibitors (Ki = 38.7 mM, Ki = 35.5 mM and Ki = 33.2 mM respectively). Propionic and butyric acids are also inhibitors (Ki = 3 mM and Ki = 2 mM).

DNA topoisomerase activities in concanavalin A-stimulated lymphocytes.

Topoisomerase activities have been measured in nuclear extracts of concanavalin A-stimulated lymphocytes. In parallel with the wave of DNA synthesis, type II topoisomerase activity was considerably increased. After 72 h treatment, this activity was stimulated approx. 20-fold over the activity in untreated cells. In contrast, type I topoisomerase was poorly stimulated after 24 h treatment, and 4-5-fold after 72 h. These findings, together with our previous results on regenerating rat liver, suggest a major role of topoisomerase II in DNA replication.

The National Evaluation of School Nutrition Programs: program impact on dietary intake.

This article describes the dietary analysis component of the National Evaluation of School Nutrition Programs. It addresses two research questions: 1) do participants and nonparticipants in the school nutrition programs have different calorie and nutrient intakes for 24 h, breakfast, and/or lunch and 2) if there are differences in the nutritional quality or total quantity of food consumed? Students who participate in the School Lunch Program get more than nonparticipants of almost all nutrients that were examined, both at lunch and during 24 h. The superior lunch and 24-h intakes of Lunch Program participants are due to the higher nutritional quality of the School Lunch compared with lunches that nonparticipants eat. The most important impact of the School Breakfast is that when the program is available, it increases the likelihood that children will eat breakfast, and children who eat breakfast have significantly higher intakes of nutrients than children who skip breakfast. The School Breakfast provides more calcium, phosphorus, protein, and magnesium than a non-US Department of Agriculture breakfast, but less vitamin A, vitamin B6, niacin, thiamin, and iron. The positive impacts of calcium and phosphorus carry over 24 h, while the negative impacts for vitamin A, vitamin B6, niacin, thiamin, and iron are made up during the remainder of the day. Although strong conclusions cannot be drawn about the impact of the Milk Program, milk is an important component of all US Department of Agriculture school nutrition programs and makes a major contribution to student dietary intake. Its presence in the meal patterns probably accounts for some of the greater nutrient intakes associated with participation in the School Lunch Program and most of the greater intakes associated with participation in the School Breakfast Program.

The National Evaluation of School Nutrition Programs: program impact on anthropometric measures.

This report describes the anthropometric analysis component of the National Evaluation of School Nutrition Programs. It addresses two research questions: First, is there a relationship between participation in the school nutrition programs and students' height, weight, and triceps fatfold, and, second, are the impacts of program participation on height, weight, and triceps fatfold different for students with different characteristics? The anthropometric analyses suggest that long-term participation in the School Lunch Program has no relationship to height but does have a small relationship to the weight of school-aged children. This is at least partly due to an increase in body fat. Program impacts do not differ for students with different income and ethnic characteristics; however, impacts are greater for older children than for younger children. The School Breakfast Program has no relationship with students' height and only weak relationships with students' weight and triceps fatfold. The Breakfast Program tends slightly to move participants toward the middle of the weight distribution and away from the extremes. Although there are statistically significant increases in weight and triceps fatfold thickness associated with participation in the School Lunch Program, they are small compared with effects of the child's sex, height, and ethnic background. Other variables, such as parents' height and weight, parents' education and family income, also have greater impacts on weight and triceps fatfold measurements than participation in the School Nutrition Programs.

Quality assurance in ambulatory nutritional care. II. Field testing of criteria.

Quality assurance criteria developed for six target populations of pregnant women and obese infants, children, and adolescents were field tested in 102 ambulatory care settings to determine whether they were relevant, understandable, measurable, behavioral, and achievable. Field testing identified specific problems in ambulatory nutritional care settings related to documentation and feasibility of using patient care records to provide data to assess quality of care and to determine how statements were formulated. Field test results were used to rewrite the criteria. Findings are consistent with those of other authors.

Quality assurance in ambulatory nutritional care. I. Past, present, and future.

Public health nutritionists have begun to coordinate efforts toward development of national standards for ambulatory nutritional care by writing and field testing criteria for selected target populations of pregnant women, infants, and children. These efforts have identified problems related to the "state of the art" in both quality assurance and nutrition science. This article reviews the literature on quality assurance in nutritional care and summarizes the current efforts culminating in publication of a preliminary guide on quality assurance in ambulatory nutrition care by the U.S. Department of Health and Human Services.

Health status and school achievement of children from Head Start and Free School Lunch Programs.

School health records of 332 children through the eighth grade were examined in a retrospective comparative analysis of physical health status and school achievement of children from Head Start and Free School Lunch Programs. The objective was to determine if nutrition early in the lives of children as a part of a comprehensive health and education program such as Head Start produces greater or different benefits for disadvantaged children than nutrition intervention later through free lunches when the child enters school. Cross-sectional longitudinal, and case-study approaches were used in the analysis. A group of no-food-program disadvantaged children and a group of advantaged children served as comparisons. Results showed that advantaged children performed better on all parameters of school achievement and health status compared with the disadvantaged children, regardless of the form of intervention. Measures of school achievement of Head Start and Free Lunch children did not differ from those of the disadvantaged comparison group, but there were significant differences in measures of health status between the disadvantaged groups. Fewer boys from Project Head Start fell below the 25th percentile for height compared with boys in the Free Lunch Program. Head Start children also scored higher in physical fitness and had fewer reported absences from school due to illness.