Accuracy of three diagnostic tests to detect tooth resorption in unowned unsocialised cats in Denmark

OBJECTIVES

To estimate the relative diagnostic sensitivity and specificity of oral clinical examination, full-mouth dental radiography, and cone-beam CT for the detection of tooth resorption in cats, and to estimate the prevalence of tooth resorption in unowned, unsocialised cats in Denmark.

MATERIALS AND METHODS

Cadavers of 144 adult cats underwent an oral examination, full-mouth dental radiography, and cone-beam CT. Sensitivity and specificity of the three tests, along with the true prevalence, overall and stratified by sex and tooth location, were estimated using latent class methods.

RESULTS

We found cone-beam CT to be the superior image modality, with a sensitivity of 99.5% and a specificity of 99.8%. Dental radiography had a sensitivity of 78.9% and a specificity of 100%, and oral clinical examination had a sensitivity of only 36.0% and specificity of 99.9%. We estimated the prevalence of tooth resorption among unowned unsocialised cats in Denmark to be 40% of adult individuals, and 6.1% of teeth.

CLINICAL SIGNIFICANCE

When dealing with tooth resorption, cone-beam CT can help the operator to find and treat affected teeth that could otherwise go undiagnosed. The prevalence of tooth resorption among unowned, unsocialised cats in Denmark does not appear to differ from other populations of cats.

Dairy cattle welfare - the relative effect of legislation, industry standards and labelled niche production in five European countries

The only common European Union (EU) legislation set up specifically to ensure the welfare of dairy cattle is for calves. As a consequence, there is wide diversity in how dairy cattle welfare is ensured in EU countries. A few countries have legal requirements for dairy cattle welfare, while in others, it is left to industry standards or niche production requirements, typically linked to various premium labels. In this paper, we compared animal welfare provisions in dairy cattle production across five countries with different combinations of legislative and other approaches: Denmark, Germany, the Netherlands, Sweden, and the United Kingdom. Firstly, we aimed to map the diversity of animal welfare initiatives. Secondly, we used the Benchmark method of expert valuations and weightings of the relative importance of individual welfare provisions. We found that Denmark and Sweden have the highest level of dairy cattle welfare provisions as measured by the Benchmark method, partly due to high legislative welfare requirements, followed by the United Kingdom, which has an extensive industry standard with very high uptake. Germany and the Netherlands, on the other hand, have lower levels of documented welfare provisions, and correspondingly a Benchmark score closer to a baseline defined by legal requirements at EU level. We also found differences in what elements of animal welfare were focussed on. Some initiatives emphasised fulfilling the social needs of cattle, while others focused more on space and freedom to move. Also, the countries with the highest Benchmark score had a relatively high level of production of organic and other specialty dairy products. We found the effect of national legislation or ambitious industry standards on dairy cattle welfare to be much larger than previous studies have found in either pigs or poultry. At a time when the EU is considering stepping up its efforts to improve animal welfare in terms of common minimum standards, the results of this study could have important policy implications. The diversity in the level of dairy cattle welfare standards found across countries may speak in favour of having shared minimum standards, both at EU level and globally. However, even among countries with a similar Benchmark score, we found a difference in the kinds of welfare provisions at work, which may make full harmonisation of standards more challenging.

Examples of proper reporting for evaluation (Stage 2 validation) of diagnostic tests for diseases listed by the World Organisation for Animal Health

Reporting and design standards are key indicators of the quality of diagnostic accuracy (validation) studies but, with the exception of aquatic animal diseases and paratuberculosis in ruminants, there is limited guidance for designing these studies in animals. There is, therefore, a need for generic guidelines that are based on disease characteristics, such as mode of transmission, latent period and pathogenesis. Comprehensive, clear and transparent reporting of primary test accuracy studies for diseases listed by the World Organisation for Animal Health (OIE) has value for the end users of diagnostic tests and, ultimately, for decision-makers, who require systematic reviews and meta-analysis of multiple tests for specified diseases and testing purposes. The recent publication of reporting standards for Bayesian latent class models, to analyse test-accuracy data from naturally occurring disease events, fills an important gap as these methods are being increasingly used for OIE-listed diseases. Adherence to design and reporting standards, as well as to guidelines, helps to ensure that research funding for test validation studies is used appropriately and that the strengths and limitations of single tests or test combinations are made clear to test users. The authors provide a review of key points that are often overlooked or misinterpreted in test validation studies, as well as two concrete examples of good practice for use as a reference point for future studies.

Changes in the soft-tissue thickness of the claw sole in Holstein heifers around calving

Claw horn disruption lesions are a common cause of lameness in dairy cattle. It is commonly agreed that they develop due to excessive pressure from the distal phalanx on the horn-producing tissue in the sole. The distal phalanx is supported by the suspensory apparatus, a large proportion of which is made up of connective tissue. It has been hypothesized that increased laxity of the connective tissue due to hormonal changes around calving may lead to decreased support of the distal phalanx, resulting in a sinking of the bone and increased pressure on the horn-producing tissue. In this longitudinal study, our first objective was to determine whether the thickness of the soft tissue related to the claw sole (the combined depth of the digital cushion and corium; soft-tissue thickness, STT) in the weight-bearing hind claws of live heifers changed around calving (the period from approximately 3 wk before calving to 2 wk after calving). Our second objective was to evaluate the relationship between the body condition score (BCS) of recruited heifers and the STT estimates we obtained. We measured STT (defined as the distance between the distal phalanx and the sole horn) in the apex and the posterior part of the sole of the hind claws of 34 Holstein heifers 4 times over 3 to 4 wk around calving. We determined STT by ultrasonographic measurements through the sole horn on weight-bearing claws. The overall mean STT at site 1 was 3.3 mm [minimum-maximum (min-max): 1.8 to 5.2 mm], and the mean at site 2 was 3.7 mm (min-max: 2.2 to 5.8). The overall mean STT was thickest in the first examination before calving [site 1: 3.4 mm (min-max: 1.9 to 4.7); site 2: 4.1 mm (min-max: 2.7 to 5.8)] and thinnest at site 1 in the second examination after calving (3.2 mm, min-max: 1.8 to 5.2) and at site 2 at the first examination after calving (3.5 mm, min-max: 2.2 to 5.0). We observed an average reduction in STT of -0.2 mm (min-max: 0.8 to -0.9 mm) at site 1 during the study period, but we did not observe this reduction in all animals. At site 2, we found an average reduction in STT of -0.6 mm (min-max: 0.8 to -1.3 mm) from 10 d before calving to 5 d after calving, corresponding to a decrease of approximately 15% (min-max: 0 to 31%). We suggest that this reduction was caused by a rotation of the distal phalanx toward the posterior part of the sole horn in the weeks around calving. During the same period, heifer BCS decreased between 0.25 and 0.5 increments in the BCS scale, but we found no correlation between BCS and STT. However, the heifers experienced many changes related to management, feeding, and time budget during the study period, and the rotation of the distal phalanx and reduction of the STT might be explained not only by calving but also by other factors that affect heifers and their claws during the transition period.

Global plant trait relationships extend to the climatic extremes of the tundra biome

The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world.

Differential somatic cell count as an additional indicator for intramammary infections in dairy cows

Mastitis, often caused by intramammary infection (IMI), is a significant problem in dairy farming globally. Somatic cell count (SCC) is widely used as a parameter for screening IMI in cows that are then treated or culled. We investigated the potential of a new parameter, differential SCC (DSCC), to detect IMI at cow level when SCC is already known. We achieved this using bacterial culture (BC) and PCR to detect 4 categories of pathogens (major, minor, other, and any) in 2 Danish dairy herds. Quarter milk samples were collected from monthly dairy herd improvement samplings over 1 yr and analyzed with BC, whereas cow-level dairy herd improvement samples were analyzed using PCR. Days in milk, parity, and IMI status had a significant effect on DSCC. Using DSCC in addition to SCC significantly improved the indication of IMI compared with using only SCC in the any pathogen category in both herds as well as the minor pathogens category in herd 2 when BC was used for detection. When PCR was used to detect IMI, the use of DSCC in addition to SCC was significant for the other pathogens category in herd 1 and the minor pathogens category in herd 2. Thus, our data revealed that DSCC can add significant information describing IMI status even when SCC is already known; however, this depends on the causative pathogen. Future studies may address how to use DSCC in practice as well as consider the availability of temporal data to potentially gain insight into the course of infection.

Prevalence of abomasal lesions in Danish Holstein cows at the time of slaughter

Abomasal lesions in cattle are challenging to diagnose because the clinical signs are often subtle and nonspecific. An increasing number of studies suggests that abomasal lesions are commonly found in cattle of all ages, but the number of recent prevalence studies in dairy cows is limited. The main objective of this study was to estimate the prevalence of abomasal lesions in a population of Danish Holstein dairy cattle in Denmark. An abattoir survey of 1,327 dairy cows apparently suitable for slaughter was performed in 2016 and 2017. Abomasal lesions are usually classified using a standardized protocol with the following types: abomasal ulcer type I: erosions and nonperforating ulcers; type II: ulcers with arterial bleeding; type III: perforating ulcer with localized peritonitis; and type IV: perforating ulcer with diffuse peritonitis. A further subdivision of the nonperforating abomasal ulcers type I were classified as subtype Ia: erosions; subtype Ib: small ulcers with localized hemorrhage; subtype Ic: ulcers with a crater-like appearance; and subtype Id: retention of the mucosa due to tissue loss with either radial wrinkles converging at a central point or perforations of the spiral folds. Type I abomasal lesions were found in 84% of the examined cows. No ulcers with arterial bleeding (type II) or perforating ulcers with diffuse peritonitis (type IV) were found, but one perforating abomasal ulcer (type III) was observed. The total number of lesions found was 7,418 and when the lesion subtypes were evaluated individually the majority of subtypes Ia and Ic were found in the pyloric area (85 and 94%, respectively), whereas lesion subtypes Ib and Id dominated the fundus/corpus area (71 and 67%, respectively). When considering lesion subtypes according to parity, there was a high prevalence of subtype Ib across the 3 groups of parity (51, 58, and 55% for parity 1, 2, and ≥3, respectively). The prevalence of lesion subtype Id seemed to increase with increasing parity, and the prevalence of lesion subtype Ia seemed to decrease with increasing parity. The prevalence of abomasal lesions was higher than that shown in similar studies of cattle at the time of slaughter. However, the expectedly most painful cases were rare, with only one perforating and no arterial bleeding ulcers found. The etiology of the different subtype I lesions is still unknown, and further investigations are needed to establish the possible influence these lesions might have on welfare and production.

Knowledge gaps that hamper prevention and control of Mycobacterium avium subspecies paratuberculosis infection

In the last decades, many regional and country-wide control programmes for Johne's disease (JD) were developed due to associated economic losses, or because of a possible association with Crohn's disease. These control programmes were often not successful, partly because management protocols were not followed, including the introduction of infected replacement cattle, because tests to identify infected animals were unreliable, and uptake by farmers was not high enough because of a perceived low return on investment. In the absence of a cure or effective commercial vaccines, control of JD is currently primarily based on herd management strategies to avoid infection of cattle and restrict within-farm and farm-to-farm transmission. Although JD control programmes have been implemented in most developed countries, lessons learned from JD prevention and control programmes are underreported. Also, JD control programmes are typically evaluated in a limited number of herds and the duration of the study is less than 5 year, making it difficult to adequately assess the efficacy of control programmes. In this manuscript, we identify the most important gaps in knowledge hampering JD prevention and control programmes, including vaccination and diagnostics. Secondly, we discuss directions that research should take to address those knowledge gaps.

Salmonella prevalence among reptiles in a zoo education setting

Clinically healthy reptiles may shed Salmonella and therefore act as a potential zoonotic threat. Most people in Northern European countries are rarely exposed to reptiles, but many zoos have education departments where children have direct contact with this group of animals. The objectives of this study were to determine the prevalence and serotype distribution of Salmonella among reptiles in the Education Department (n = 55) at Copenhagen Zoo and compare it to the Zoo's main reptile collection (n = 145) to evaluate the zoonotic risk. Salmonella was isolated from cloacal swabs by selective enrichment, and a single isolate from each positive sample was further identified by biochemical tests and serotyped. The overall prevalence was 35% (69/200) with significant difference between the Education Department (64%, 35/55) and the main reptile collection (23%, 34/145). A total of 28 serotypes were detected. Ten serotypes were isolated from more than one specimen and four from more than one species. Salmonella enterica subsp. enterica serovar Eastbourne was the predominant serotype (32%, 22/69) and was also the serotype isolated from most reptile species (n = 7). Transmission of serotypes from one department to another was very limited indicated by the serotype distribution. Despite the relative high prevalence observed among the reptiles in the Zoo's Education Department compared to the reptiles in the Zoo's main reptile collection, no Salmonella cases have been linked to the Zoo, and Salmonella ser. Eastbourne is very rarely isolated from humans in Denmark. Simple hygienic procedures such as hand washing which is consistently carried out following handling of reptiles at the Education Department may reduce the risk and therefore contribute to this low prevalence.

Strategies for time of culling in control of paratuberculosis in dairy herds

Effect of time for culling cows infected with Mycobacterium avium ssp. paratuberculosis on prevalence and profitability was identified through simulations. Seven test-and-cull strategies with different culling criteria and no attempts to close infection routes were compared with strategies with (1) no control and (2) closure of infection routes and no culling. The effects on true prevalence and gross margin were evaluated in a herd with typical reproduction management (heat detection rate of 38%). This was repeated in a herd with poor reproduction management (heat detection rate of 28%), because poor reproduction leads to lack of replacement animals, which was hypothesized to affect the economic effects of culling. Effects of varying prices of milk, replacement heifers, and hourly wages were also evaluated. The simulated results predicted that immediate culling after the first positive antibody ELISA test would be the most effective culling strategy to reduce prevalence. However, closing transmission routes was even more effective in reducing the prevalence. In the first 3 to 6 yr, all test-and-cull strategies reduced gross margin by US$5 to 55/stall per year. These losses were fully compensated by increased gross margin in yr 6 to 19. In the short run (7 yr with typical reproduction and 10 yr with poor reproduction), it was most profitable to cull test-positive cows when their milk yield decreased below 85% of that expected according to their parity and lactation stage, especially in herds with poor reproduction management. However, this strategy only stabilized the prevalence and did not reduce it. In the long term (>7 yr from implementation of a strategy), it was most profitable to cull cows immediately or as soon as possible after testing positive the first time. Varying milk prices did not affect the ranking between the different culling strategies. Increased market price (20%) of replacement heifers made all culling strategies less profitable and made culling based on a milk yield criterion the most profitable culling strategy for a longer period (11 to 13 yr). A 20% reduction in heifer price made immediate culling after a positive test the most profitable strategy overall in herds with typical reproduction, and after 9 yr in herd with poor reproduction. To conclude, the ideal culling strategy depends on the aim of intervention, the time horizon, and the reproductive capabilities combined with prices of replacement animals.

Bayesian analysis of longitudinal Johne's disease diagnostic data without a gold standard test

A Bayesian methodology was developed based on a latent change-point model to evaluate the performance of milk ELISA and fecal culture tests for longitudinal Johne's disease diagnostic data. The situation of no perfect reference test was considered; that is, no "gold standard." A change-point process with a Weibull survival hazard function was used to model the progression of the hidden disease status. The model adjusted for the fixed effects of covariate variables and random effects of subject on the diagnostic testing procedure. Markov chain Monte Carlo methods were used to compute the posterior estimates of the model parameters that provide the basis for inference concerning the accuracy of the diagnostic procedure. Based on the Bayesian approach, the posterior probability distribution of the change-point onset time can be obtained and used as a criterion for infection diagnosis. An application is presented to an analysis of ELISA and fecal culture test outcomes in the diagnostic testing of paratuberculosis (Johne's disease) for a Danish longitudinal study from January 2000 to March 2003. The posterior probability criterion based on the Bayesian model with 4 repeated observations has an area under the receiver operating characteristic curve (AUC) of 0.984, and is superior to the raw ELISA (AUC=0.911) and fecal culture (sensitivity=0.358, specificity=0.980) tests for Johne's disease diagnosis.

Amendment of arsenic and chromium polluted soil from wood preservation by iron residues from water treatment

An iron-rich water treatment residue (WTR) consisting mainly of ferrihydrite was used for immobilization of arsenic and chromium in a soil contaminated by wood preservatives. A leaching batch experiment was conducted using two soils, a highly contaminated soil (1033 mg kg(-1) As and 371 mg kg(-1) Cr) and slightly contaminated soil (22 5mg kg(-1) As and 27 mg kg(-1) Cr). Compared to an untreated reference soil, amendment with 5% WTR reduced leaching in the highly contaminated soil by 91% for Cr and 98% for As. No aging effect was observed after 103 d. In a small field experiment, soil was mixed with 2.5% WTR in situ. Pore water was extracted during 3 years from the amended soil and a control site. Pore water arsenic concentrations in the amended soil were more than two orders of magnitude lower than in the control for the upper samplers. An increased release of arsenic was observed during winter in both fields, mostly in the deepest samplers. This is likely due to the formation of a pseudo-gley because of precipitation surplus. Stabilization of arsenic and chromium contaminated soil using WTR is a promising method but the transformation of ferrihydrite in soil proves a concern in case of waterlogged soils. Still the amendment minimized the leaching of arsenic, even in cases of seasonal releases.

Increased incidence of Mycoplasma pneumoniae infections detected by laboratory-based surveillance in Denmark in 2010

In Denmark recurrent epidemics of Mycoplasma pneumoniae infections have been described since the 1950s at intervals of approximately four to six years. The latest epidemic occurred in 2004/05 followed by two years of high incidence and more than three years of low incidence. Due to a recent increase in diagnosed cases since late summer 2010, we conducted a survey of positive M. pneumoniae PCR tests performed by clinical microbiology departments in Denmark, which indicated that a new epidemic may be underway.

A new small-angle X-ray scattering set-up on the crystallography beamline I711 at MAX-lab

A small-angle X-ray scattering (SAXS) set-up has recently been developed at beamline I711 at the MAX II storage ring in Lund (Sweden). An overview of the required modifications is presented here together with a number of application examples. The accessible q range in a SAXS experiment is 0.009-0.3 A(-1) for the standard set-up but depends on the sample-to-detector distance, detector offset, beamstop size and wavelength. The SAXS camera has been designed to have a low background and has three collinear slit sets for collimating the incident beam. The standard beam size is about 0.37 mm x 0.37 mm (full width at half-maximum) at the sample position, with a flux of 4 x 10(10) photons s(-1) and lambda = 1.1 A. The vacuum is of the order of 0.05 mbar in the unbroken beam path from the first slits until the exit window in front of the detector. A large sample chamber with a number of lead-throughs allows different sample environments to be mounted. This station is used for measurements on weakly scattering proteins in solutions and also for colloids, polymers and other nanoscale structures. A special application supported by the beamline is the effort to establish a micro-fluidic sample environment for structural analysis of samples that are only available in limited quantities. Overall, this work demonstrates how a cost-effective SAXS station can be constructed on a multipurpose beamline.

Human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) case reporting in the World Health Organization European Region in 2006

This article presents information on HIV and AIDS case reporting systems as part of a survey on HIV/AIDS surveillance practices in the World Health Organization (WHO) European Region. A standardised questionnaire was sent to the 53 national correspondents of the European Centre for the Epidemiological Monitoring of AIDS(EuroHIV). The HIV and AIDS case reporting section of the questionnaire comprised four parts: data collection system, HIV/AIDS case definition for surveillance, variables collected, and evaluation of surveillance systems). Individual-based data collection systems for HIV case reports have been implemented in 43 of 44 countries in the WHO European Region and for AIDS case reports in all the countries. For HIV case reports, a coded identifier is used in 28 countries, and full names are used in 11 countries. The European AIDS case definition has been adopted in 35 countries(80%). Information on molecular epidemiology is available in 30 countries, and HIV drug resistance is monitored in 11 countries.HIV/AIDS case reporting systems have been evaluated for underreporting in 17 countries and for completeness in 11 countries.This article outlines the future needs for HIV/AIDS surveillance and presents recommendations on how to improve data comparability across European countries in the WHO region.

Impact of the hard-to-cook phenomenon on phenolic antioxidants in dry beans (Phaseolus vulgaris)

Epidemiological studies have established a link between consumption of dry beans and lower incidence of degenerative diseases. This relationship is attributed in part to properties of natural antioxidants present in beans. The objective of this study was to determine if the hard-to-cook (HTC) phenomenon in beans had a negative effect on the content of free and bound phenolic antioxidants and antioxidant capacity. Folin-Ciocalteu, Trolox equivalent antioxidant capacity, and HPLC methods were used to quantify the content of phenolic acids and antioxidant capacity. Results showed that the HTC phenomenon did not equally affect the content and antioxidant capacity of phenolic acids in different bean cultivars. Black beans were most affected, the contents of free and acid hydrolyzable phenolic acids being reduced by 35 and 36%, respectively, and the antioxidant activity by 18 and 25%, respectively. This study showed that the HTC phenomenon affected a potential nutritive characteristic of dry beans.

Evaluation of test-strategies for estimating probability of low prevalence of paratuberculosis in Danish dairy herds

Paratuberculosis is a chronic infection affecting cattle and other ruminants. In the dairy industry, losses due to paratuberculosis can be substantial in infected herds and several countries have implemented national programmes based on herd-classification to manage the disease. The aim of this study was to develop a method to estimate the probability of low within-herd prevalence of paratuberculosis for Danish dairy herds. A stochastic simulation model was developed using the R programming environment. Features of this model included: use of age-specific estimates of test-sensitivity and specificity; use of a distribution of observed values (rather than a fixed, low value) for design prevalence; and estimates of the probability of low prevalence (PrLow) based on a specific number of test-positive animals, rather than for a result less than or equal to a specified cut-point number of reactors. Using this model, five herd-testing strategies were evaluated: (1) milk-ELISA on all lactating cows; (2) milk-ELISA on lactating cows<or=4 years old; (3) milk-ELISA on lactating cows>4 years old; (4) faecal culture on all lactating cows; and (5) milk-ELISA plus faecal culture in series on all lactating cows. The five testing strategies were evaluated using observed milk-ELISA results from 19 Danish dairy herds as well as for simulated results from the same herds assuming that they were uninfected. Whole-herd milk-ELISA was the preferred strategy, and considered the most cost-effective strategy of the five alternatives. The five strategies were all efficient in detecting infection, i.e. estimating a low PrLow in infected herds, however, PrLow estimates for milk-ELISA on age-cohorts were too low in simulated uninfected herds and the strategies involving faecal culture were too expensive to be of practical interest. For simulated uninfected herds, whole-herd milk-ELISA resulted in median PrLow values>0.9 for most herds, depending on herd size and age-structure. None of the strategies provided enough power to establish a high PrLow in smaller herds, or herds with a younger age-structure. Despite this, it appears as if the method is a useful approach for herd-classification for most herds in the Danish dairy industry.

Association between the presence of antibodies to Mycobacterium avium subspecies paratuberculosis and somatic cell count

Somatic cell counts (SCC) in bulk tank milk delivered for human consumption are one of the indicators of milk quality and are used for milk pricing. Consequently, milk from cows with high SCC is frequently used by farmers for feeding of calves to lower the SCC in bulk tank milk. Young calves are more susceptible to Mycobacterium avium ssp. paratuberculosis (MAP) and may acquire the infection early in life through ingestion of MAP-contaminated milk. The occurrence of MAP antibodies can be an indicator of MAP shedding. Because MAP can be shed in milk from infected cows, and antibodies to MAP can be an indicator of the infectious status, an association between antibodies to MAP and high SCC can result in high-SCC milk being at risk of containing MAP. Feeding milk containing high SCC to susceptible calves may result in MAP infections. Somatic cell counts and MAP antibodies in milk were measured repeatedly in 7,251 cows from 26 Danish dairy herds to investigate the association between the occurrence of MAP antibodies and high SCC. The results of robust regression showed a log-linear relationship between the age at first positive ELISA and the age at first high SCC sample (R2 = 0.51). Of the 1,733 cows positive for MAP antibodies and with high SCC, high SCC was detected prior to MAP antibodies in 46% of the cows. Still, in 40% of the cows, MAP antibodies were detected before a high SCC. Therefore, the findings do not point to a causal relationship between high SCC and antibodies to MAP, but suggest a strong association and highlight a potentially increased risk of MAP transmission when milk with high SCC is fed to calves.

Bayesian mixture models for within-herd prevalence estimates of bovine paratuberculosis based on a continuous ELISA response

Diagnostic inference by use of assays such as ELISA is usually done by dichotomizing the optical density (OD)-values based on a predetermined cut-off. For paratuberculosis, a slowly developing infection in cattle and other ruminants, it is known that laboratory factors as well as animal specific covariates influence the OD-value, but while laboratory factors are adjusted for, the animal specific covariates are seldom utilized when establishing cut-offs. Furthermore, when dichotomizing an OD-value, information is lost. Considering the poor diagnostic performance of ELISAs for diagnosis of paratuberculosis, a framework for utilizing the continuous OD-values as well as known coavariates could be useful in addition to the traditional approaches, e.g. for estimating within-herd prevalences. The objective of this study was to develop a Bayesian mixture model with two components describing the continuous OD response of infected and non-infected cows, while adjusting for known covariates. Based on this model, four different within-herd prevalence indicators were considered: the mean prevalence in the herd; the age adjusted prevalence of the herd for better between-herd comparisons; the rank of the age adjusted prevalence to better compare across time; and a threshold-based prevalence to describe differences between herds. For comparison, the within-herd prevalence and associated rank using a traditional dichotomization approach based on a single cut-off for an OD corrected for laboratory variation was estimated in a Bayesian model with priors for sensitivity and specificity. The models were applied to the OD-values of a milk ELISA using samples from all lactating cows in 100 Danish dairy herds in three sampling rounds 13 months apart. The results of the comparison showed that including covariates in the mixture model reduced the uncertainty of the prevalence estimates compared to the cut-off based estimates. This allowed a more informative ranking of the herds where low ranking and high ranking herds were easier to identify.

Assessment of management-related risk factors for paratuberculosis in Danish dairy herds using Bayesian mixture models

Transmission of Mycobacterium avium subsp. paratuberculosis (Map) to susceptible animals is primarily considered to occur via faeces and milk originating from infectious cows. However, studies of factors resulting in increased transmission of Map are difficult to perform due to a long and unpredictable incubation period and inaccurate diagnostic tests. A multi-level Bayesian mixture model has been shown to predict the infection status of an individual cow more precisely than traditional cut-off based methods used for interpretation of diagnostic test-information, thereby increasing the precision of the diagnostic information. The objective of our study was to assess management-related risk factors for within-herd transmission of Map. Management-related risk factors were recorded in 97 Danish dairy herds. Twenty-six months following that recording, the antibody status of all lactating cows (n=7,410) in the same herds was measured by the use of an ELISA. A multi-level Bayesian mixture model was used to assess the association between the probability of infection of individual cows and 41 herd-level management-related risk factors using univariable analyses. In this model, the continuous OD value was used to estimate the probability of infection, corrected for known animal covariates and laboratory factors. The statistical significance of the potential risk factors was assessed by calculating odds ratios and their 95% credibility posterior intervals. Four significant risk factors were identified: housing of cows in bed stalls compared to housing in tie stalls; low level of hygiene in the feeding area of calving areas; low amounts of straw in the bedding of the calving area; high animal density among young stock >12 months of age. Surprisingly, the hygiene level in the calving area was not found to affect the odds of infection.

Host-specific bacterial lineages in the taxon 2 and 3 complex of Pasteurellaceae

The aim of the investigation was to determine the genetic relationship of a phenotypically diverse strain collection of epidemiologically unrelated strains from the taxon 2 and 3 complex of Bisgaard isolated from different hosts. A total of 325 isolates belonging to the taxon 2 and 3 complex of Bisgaard was characterized phenotypically in 82 characters. The genetic relationship among a subset of 60 isolates was investigated by amplified fragment length polymorphism (AFLP). The isolates were selected aiming at including the broadest diversity with regards to phenotype and host spectrum. The results suggested a statistically clear association between AFLP clusters and the host species families Columbidae (pigeon, dove), Anatidae (duck, goose) and Psittacidae (parrot, parakeet, budgerigar), respectively. This association was further supported by results from previous whole cell protein profiling and DNA:DNA hybridization studies. In conclusion, it appears that distinct genetic lineages within the taxon 2 and 3 complex of Bisgaard have evolved specificity for host bird species of different families. The observed host specificity of taxon 2 and 3 organisms may be used in future diagnostics and studies elucidating aspects of pathogenicity and epidemiology associated with the different lineages and their respective hosts.

Age at Occurrence of Mycobacterium avium Subspecies paratuberculosis in Naturally Infected Dairy Cows

Paratuberculosis is a chronic infection of ruminants and other species caused by Mycobacterium avium ssp. paratuberculosis (Map). Establishing test strategies for paratuberculosis will require insight into the temporal aspects of certainty with a given test. In this study, the age at which cows tested positive by ELISA and fecal culture (FC) was investigated by use of time-to-event analyses. The effects of herd, parity, and shedding group were evaluated at the age of test-positive ELISA and FC, respectively. Finally, the test frequency was investigated for the probability of cows being tested ELISA-positive. Milk and fecal samples were collected repeatedly over a 3-yr period from 1,776 Danish dairy cows from 8 herds. The milk samples were tested for the presence of antibodies by using an ELISA, and an FC test was used for detection of Map. Repeated ELISA testing detected 98 and 95% of cows classified as high and low shedders, respectively, suggesting that most infected cows develop antibodies. Among the high shedders, 50% were positive before 4.3 yr of age (quartiles 1 to 3: 3.4 to 5.7 yr of age). Repeated FC detected only 72% of the cows that were ELISA-positive, and 50% of the ELISA-positive cows were detected by FC at 7.6 yr of age. The age with the highest probability of testing positive was determined as the interval with the steepest slope in the survival probability plots. The highest probability of testing positive by ELISA was from 2.5 to 4.5 yr of age. The highest probability of testing positive by FC was from 2.5 to 5.5 yr of age. For both ELISA and FC, testing positive was highest in the first 300 d in milk. For cows younger than 4 yr of age, monthly testing with ELISA, compared with testing every 2 yr, could increase the probability of detecting cows with antibodies by 19%. In older cows, there were no apparent differences in the probability of testing positive by monthly sampling compared with sampling every second year. Therefore, for older animals the effect of more frequent sampling would be for early detection rather than to obtain additional information. Cows shedding high numbers of Map will produce antibodies, although not necessarily concomitantly with the shedding. These antibodies can be detected by ELISA with a test strategy that is different for younger and older cows. We suggest testing younger cows more frequently than older cows and that testing should be done prior to 350 d in milk.

Estimating receiver operating characteristic curves with covariates when there is no perfect reference test for diagnosis of Johne's disease

Paratuberculosis (Johne's disease) is a significant animal health problem. Evaluation of diagnostic tests for Johne's disease has been difficult due to lack of a gold standard test. In recent years, there has been interest in receiver operating characteristic (ROC) curve estimation without any gold standard test. Typically, either Bayesian or maximum likelihood methods are proposed. Although these methods overcome the lack of a gold standard test in ROC curve estimation, little work has been done to incorporate covariates in the analysis. In this paper, we propose a method for estimation of ROC curves based on statistical models to adjust for covariate effects when the true disease states of test animals are unknown. The covariates may be correlated with the disease process or with the diagnostic testing procedure, or both. We propose a 2-part Bayesian model: first, a logistic regression model for disease prevalence is used to fit the covariates; second, a linear model is used to fit the covariates to the distribution of test scores. We used Markov chain Monte Carlo methods to compute the posterior estimates of the sensitivities and specificities that provide the groundwork for inference concerning the diagnostic procedure's accuracy. We applied the methodology to milk ELISA scores from several dairy-cow herds for the diagnostic testing of paratuberculosis. We found that both milk yield and its interaction with age had significant effects on the disease process whereas only milk yield was significant on the testing procedure.

Activity and Nature of Plasminogen Activators Associated with the Casein Micelle

In fresh milk, plasminogen, the zymogen form of plasmin (PL), is the predominant form. Therefore, plasminogen activators (PA) can contribute significantly to PL activity in milk. Both tissue-type PA (tPA) and urokinase-type PA (uPA) exist in milk; however, contradictory findings have been reported for which type of PA is most closely associated with the casein micelles. Little is known about the factors that might lead to variations in the individual activities of the PA. The objective of this work was therefore to investigate possible factors that might affect the association of tPA and uPA with the casein micelle and their activities thereafter. Plasminogen activators were isolated from milk samples with different somatic cell counts following 2 different isolation protocols. Determination of uPA, tPA, and PL activities was carried out quantitatively following chromogenic assays using 2 different substrates, and qualitatively using specialized sodium dodecyl sulfate-PAGE. Different isolation methods and conditions led to differences in uPA, tPA, and PL activities. Urokinase-type PA activity was significantly higher in PA fractions isolated from milk with high somatic cell counts than from milk with low somatic cell counts. Activity results indicated that in pasteurized milk uPA could dissociate from the somatic cells and bind to casein. Moreover, a high level of PL in isolated PA fractions contributed to significantly enhanced PA activities. Overall, results confirmed the association of both uPA and tPA with the casein micelle; however, their amounts, activities, and molecular weights varied based on the nature of the milk and methods of separation, with uPA being the PA with greater potential to affect plasminogen activation in milk.

Cyclooxygenase type 2 is increased in obstructed rat and human ureter and contributes to pelvic pressure increase after obstruction

Prostanoids exert physiological effects on ureteral contractility that may lead to pressure changes and pain during obstruction. In the present study, we examined whether (1) obstruction changes the expression of the two cyclooxygenase (COX) isoforms, COX-1 and COX-2 in human and rat ureters and (2) administration of a selective COX-2 inhibitor influences the pelvic pressure change after experimental ureteral obstruction. Rats were subjected to bilateral ureter obstruction. Ureters were removed and dissected into a proximal dilated and distal non-dilated segment. RNA and protein were extracted and analyzed for cyclooxygenase expression by quantitative polymerase chain reaction and Western blotting. Human ureter samples were obtained from patients undergoing radical nephrectomy. Rat and human ureteral samples were processed for immunohistochemistry. COX-1, but not COX-2 mRNA, was readily detected in the normal rat ureter. COX-2 mRNA and protein expression was increased in the proximal dilated ureter compared to distal non-dilated ureter. This increased COX-2 expression was associated with increased urinary prostaglandin E2 (PGE2) excretion after release of obstruction. Immunohistochemistry showed increased COX-2 labeling in surface epithelium and smooth muscle layers in both rat and human obstructed ureters compared to control ureters. Furthermore, contractile PGE2-EP1 and thromboxane TP receptors were expressed in ureteral smooth muscle. Systemic treatment with the COX-2 selective inhibitor parecoxib (5 mg/kg/day) attenuated the pelvic pressure increase during obstruction. In summary, COX-2 expression is significantly increased in the ureteral wall in response to obstruction in the rat and human ureter and COX-2 activity contributes to increased pelvic pressure after obstruction.

Typing of Legionella isolates during an epidemiological investigation can be helpful but also misleading: an example from Greece

The guidelines of the European Working Group for Legionella Infections (EWGLI) [1] are mainly based on epidemiological criteria, because clinical diagnosis of the infection is seldom based on the isolation of this bacterium from the patient

Age-specific characteristics of ELISA and fecal culture for purpose-specific testing for paratuberculosis

Paratuberculosis is a chronic infection, and animals are not equally affected by it. Therefore, diagnostic tests that are able to detect different stages of the infection are needed for objective decision making. A longitudinal study was carried out to describe the ability of 2 tests to predict 2 conditions in dairy cattle: "infection" and "infectious," exemplifying 2 different purposes of testing. "Infection" is the term of choice for certification and eradication purposes, and "infectious" is more relevant for control purposes. In the study period of 3 yr, repeated sampling of milk (n = 23,219) and feces (n = 8,832) was performed. A total of 1,985 Danish dairy cows provided material for the study. Milk samples were analyzed for antibodies using an ELISA, and fecal samples were analyzed for mycobacteria by culture. A reference test to correctly classify cattle antemortem does not exist; thus, "infection" and "infectious" were defined by repeated testing using one test as the condition to be detected by the other test. Fecal culture responses were evaluated against antibody status, and ELISA responses were evaluated against detected bacterial shedding. The results of this study indicate that the ability of both tests to detect "infection" increases almost linearly from 2 to 5 yr of age, whereas the ability of both tests to detect "infectious" is not affected by age. Purpose-specific tests are required to appropriately interpret and use test results for management of paratuberculosis, and relevant covariates, such as age, should be included when possible.

Continuous-data diagnostic tests for paratuberculosis as a multistage disease

We devised a general method for interpretation of multistage diseases using continuous-data diagnostic tests. As an example, we used paratuberculosis as a multistage infection with 2 stages of infection as well as a noninfected state. Using data from a Danish research project, a fecal culture testing scheme was linked to an indirect ELISA and adjusted for covariates (parity, age at first calving, and days in milk). We used the log-transformed optical densities in a Bayesian network to obtain the probabilities for each of the 3 infection stages for a given optical density (adjusted for covariates). The strength of this approach was that the uncertainty associated with a test was imposed directly on the individual test result rather than aggregated into the population-based measures of test properties (i.e., sensitivity and specificity).

Effects of Pseudomonas fluorescens M3/6 Bacterial Protease on Plasmin System and Plasminogen Activation

Heat-stable proteases produced by the psychrotroph Pseudomonas fluorescens M3/6 have been shown to affect the plasmin system in milk, which in turn will affect the quality of processed milk. The M3/6 proteases cause dissociation of plasmin from casein in minimally processed milk. The objective of this work was to study the effect of M3/6 protease on the plasmin system, as well as its role in plasminogen activation, under commonly applied cheese-making conditions. Isolated M3/6 protease was added to raw milk, which then was pasteurized, and subjected to pH adjustments and CaCl2 addition. Casein and whey fractions were separated by chymosin treatment then analyzed for plasmin activity. Individual and interaction effects of M3/6 protease addition, pH treatment, and CaCl2 addition on plasmin activity were studied. Enzyme activity assays were carried out to study individually the effect of M3/6 protease on plasmin system components. Kinetic parameters were calculated to characterize the effect of M3/6 protease on plasminogen activation. Plasmin activity increased in the curd fractions of the protease-treated milk that was subjected to conditions most resembling cheese-making conditions, indicating that M3/6 protease triggered plasminogen activation rather than dissociation of plasmin from casein micelles. Results from the studies on plasminogen activation confirmed that the observed activation of plasminogen in protease-treated samples subjected to cheese making conditions was attributed to the stimulatory effect M3/6 protease had on plasminogen activators (PA). The M3/6 protease stimulated human and bovine PA by increasing their activity 4.5- and 2.5-fold, respectively. Similarly, the catalytic efficiencies of human urokinase-type PA and bovine PA were increased in the presence of M3/6 protease by 12- and 4-fold, respectively. Our research presented a basic step toward fully understanding the effect of bacterial proteases under different processing conditions, where the gathered information can aid in better control of processing conditions based on the desired outcome.

Histopathology of Oligofructose-Induced Acute Laminitis in Heifers

Histopathology of the dermo-epidermal junction in the lamellar region of front claws was examined in 6 dairy heifers given an alimentary oligofructose overload and compared with sections from a control group of 6 heifers. Four of the 6 heifers administered oligofructose developed clinical signs of acute laminitis before they were euthanized. Postmortem samples from front claws were processed for histology. Eleven histopathologic characteristics were selected from the existing literature and used in a blinded evaluation of sections. In total, 104 front claw samples, including 8 samples from 2 cows having spontaneously occurring acute laminitis, were evaluated histologically using hematoxylin and eosin as well as periodic acid-Schiff staining. The major morphological features associated with oligofructose-induced acute clinical laminitis were stretching of lamellae, dermal edema, hemorrhage, changes in basal cell morphology, presence of white blood cells in dermis, and signs of basement membrane detachment. Changes at the lamellar junction of claw tissue affected by oligofructose-induced clinical laminitis resembled tissue from the 2 cows suffering from spontaneous acute clinical laminitis, and generally were consistent with existing descriptions of laminitis histopathology. Important exceptions to existing descriptions in the literature were stretching of lamellae and basement membrane changes. Not previously described, we considered these early signs of acute laminitis. In conclusion, this study documents that oligofructose-induced clinical laminitis is associated with histopathological changes at the lamellar interface. A weakened dermo-epidermal junction is a possible intermediate stage in the pathophysiology of bovine sole ulceration at the typical site.

Comparison of chemical characteristics of three soybean cysteine proteinase inhibitors

Three recombinant soybean cysteine proteinase inhibitors (rSCPIs) L1, R1, and N2 were chemically characterized. These inhibitors have the potential to inhibit the growth and development of three major agricultural crop pests known to utilize cysteine proteinases (CPs) for protein digestion: Western corn rootworm, Colorado potato beetle, and cowpea weevil. Characterization data obtained show differences between the inhibitors and will be needed to consider the use of rSCPIs to create insect resistance in plants.

Effectiveness of recombinant soybean cysteine proteinase inhibitors against selected crop pests

Three recombinant soybean cysteine proteinase inhibitors (rSCPIs), L1, R1 and N2, were assessed for their potential to inhibit the growth and development of three major agricultural crop pests known to utilize digestive cysteine proteinases: Western corn rootworm (Diabrotica virgifera virgifera, WCR), Colorado potato beetle (Leptinotarsa decemlineata, CPB) and cowpea weevil (Callosobruchus maculatus, CW). In vitro experiments showed that cysteine proteinase activities in the crude gut extracts of the WCR, CPB, and CW were inhibited to various degrees by the three rSCPIs. Of the three rSCPIs tested, N2 was most effective in inhibiting the crude gut extract of WCR, CPB, and CW (50% inhibition at 5 x 10(-8), 5 x 10(-8), and 3 x 10(-7) M, respectively). The L1 was the least potent of the three CPIs tested, with 50% inhibition at 5 x 10(-6) M of the crude gut extracts of WCR. Results of in vivo experiments conducted to assess the effect of the three rSCPIs on the vital growth parameters of WCR, CPB and CW were consistent with results of the in vitro experiments.

Effects of native and denatured whey proteins on plasminogen activator activity

The plasmin system native to bovine milk consists of the caseinolytic serine proteinase plasmin; its inactive zymogen, plasminogen; plasminogen activators; and inhibitors. Evidence in the literature indicates that whey proteins may inhibit plasmin activity, but there is very little mention of their effect on plasminogen activators. The objective of this research was to determine the effect of both unheated and heat-denatured beta-lactoglobulin (beta-LG), alpha-lactalbumin (alpha-LA), and BSA on plasminogen activators. Plasminogen activator activity was significantly stimulated by non-heat treated and denatured alpha-LA as well as by denatured beta-LG. The stimulation effect by these whey proteins was kinetically characterized, which showed that all 3 significantly increased the rate of plasminogen activation. The stimulation effect was shown to be independent of any effect of the whey proteins on plasmin activity by testing 2 different substrates, d-Val-Leu-Lys p-nitroanilide (S-2251) and Spectrozyme PL (Spec PL), in a plasmin assay. Results using S-2251 confirmed the inhibitory effect of whey proteins on plasmin observed by several researchers. However, use of SpecPL did not suggest inhibition. Ligand binding studies showed this discrepancy to be due to significant interaction between S-2251 and the whey proteins. Overall, this study indicates that whey protein incorporation into cheese may not hinder plasmin activity and may stimulate plasminogen activation. Furthermore, the results indicate the need for careful consideration of the type of synthetic substrate chosen for model work involving whey proteins and the plasmin system.

Genetic Variation and Heritability of the Antibody Response to Mycobacterium avium subspecies paratuberculosis in Danish Holstein Cows

The purpose of this study was to estimate the genetic variation and the heritability of the ability to establish an immune response by producing antibodies to Mycobacterium avium subsp. paratuberculosis. Antibody levels were determined using an ELISA and measuring optical density (OD) values from milk samples of 11,535 cows from 99 herds. The pedigree of the 11,535 cows and information about days in milk, parity, milk yield, and others were obtained from the Danish Cattle database. The statistical analyses were made using a bivariate mixed animal model. The bivariate model with daily milk yield and OD as dependent variables showed a significant heritability of the ability to produce Mycobacterium avium subsp. paratuberculosis antibodies of 0.102 (genetic variance=0.054) and a nonsignificant genetic correlation of -0.037 between daily milk yield and OD. When a sire model was used, the estimated heritability was 0.091. To evaluate whether intrauterine infection could be reflected in the OD, variation among 2715 dam-daughter or maternal sister groups was also estimated. Variation in this data was nonsignificant, possibly because only very few clinical cases or end-stage cows, i.e., heavy bacterial shedders may have been represented among the cows sampled. It does not appear that intrauterine transmission is of major importance in the transmission of paratuberculosis.

Relationship between antibodies against Mycobacterium avium subsp. paratuberculosis in milk and shape of lactation curves

To analyze how infection with Mycobacterium avium subsp. paratuberculosis (MAP) affects the shape of lactation curves, a three-level hierarchical test-day model was set up with fat-corrected test-day milk yield (FCTM) as response. Milk samples from 6955 cows in 108 Danish dairy herds were tested with ELISA to detect antibodies against MAP. Optical densities (ODs) recorded on a continuous scale were standardized according to parity and stage of lactation. In addition to standardized ODs (stOD), seven fixed covariates, quadratic terms and first-order interactions were included in the model. Cow and cow nested in herd were included as random effects. Cows of first, second and higher parities were analyzed separately. The lactation curves after peak yield were significantly less persistent in young infected cows, where an increase of one stOD unit was associated with a depression of the milk yield per day through day 305 of 3.7 kg FCTM in first parity and 2.7 kg FCTM in second parity. In second-parity cows, the lactation curve also was both depressed through the entire lactation and more steep after 60 days in milk (DIM). In third and older parities, a significant effect of the quadratic term of stOD indicated exponentially increased losses with increased ODs.

Analysis of hard-to-cook red and black common beans using Fourier transform infrared spectroscopy

Extracted fractions from black and red common beans (Phaseolus vulgaris) were studied using Fourier transform infrared spectroscopy (FT-IR). Beans were stored under three conditions: control at 4 degrees C; hard-to-cook (HTC) at 29 degrees C, 65% RH for 3.5 months; and refrigerated at 2 degrees C, 79% RH for 3.5 months after a HTC period (called HTC-refrigerated). Two fractions isolated from the beans, the soluble pectin fraction (SPF) and the water insoluble residue of the cell wall (WIRCW), were analyzed using diffuse reflectance (DRIFTS) FT-IR. The soaking water and cooking water from the beans were also studied using attenuated total reflectance (ATR) FT-IR. The DRIFTS FT-IR results from the SPF and WIRCW fractions were consistent with previously published data for Carioca beans showing that in general, more phenolic compounds were associated with the SPF of HTC beans than in the control beans. Results also showed that HTC-refrigerated beans had higher concentrations of phenolic compounds than control beans in the SPF. The ATR FT-IR results for soaking and cooking waters from the HTC-refrigerated and HTC beans had higher concentrations of absorbing compounds than the control beans, indicating that they lost more constituents to the water. Additionally, results indicate that the mechanism(s) for reversibility of the HTC defect could be different than the one(s) involved in the development of the defect.

Comparison of contamination and growth of Mycobacterium avium subsp. paratuberculosis on two different media

AIMS

The purpose of the study was to compare the growth of Mycobacterium avium subsp. paratuberculosis (Map) and the degree of contamination on Herrold's egg yolk medium (HEYM) and modified Löwenstein-Jensen medium (LJ).

METHODS AND RESULTS

Culture of 2513 faecal samples from dairy cows was performed on each of the two media. The media were read after 5, 8 and 12 weeks of incubation. Overall, the proportion of contaminated samples was significantly higher on LJ (14.2%) than on HEYM (13.2%) after 12 weeks but the degree of contamination was slightly less on LJ. After 8 weeks of incubation, only 1.0% of the samples were Map positive in LJ with 4.9% on HEYM. After 12 weeks of incubation, 3.3% of the samples were Map positive in LJ whereas 6.9% were positive in HEYM. All suspect and culture positive samples were confirmed by IS900 PCR.

CONCLUSIONS

HEYM supported growth of Map significantly better and faster than LJ, however it could not be determined conclusively which of the two media that provided the highest degree of decontamination when the incubation time was also included.

SIGNIFICANCE AND IMPACT OF THE STUDY

HEYM should be the primary medium rather than LJ for detection of Map in cattle.

FTIR determination of ligand-induced secondary and tertiary structural changes in bovine plasminogen

Human plasminogen undergoes a large tertiary structural change in the presence of lysine derivatives (e.g. ε-amino caproic acid, EACA). This change facilitates human plasminogen activation by human plasminogen activators, resulting in elevated blood plasmin levels. It is hypothesized that this structure-function relationship is similar for bovine plasminogen. The objectives of this study were to investigate the effect of the ligand EACA on the secondary structure of plasminogen (bovine, human, and rabbit) and the tertiary structure of bovine plasminogen using Fourier-transform infrared spectroscopy (FTIR). Spectra of plasminogen, EACA, and a mixture of plasminogen and EACA in water and deuterium were collected using FTIR. Fourier-self deconvoluted spectra in the amide I region (1700–1600 cm−1) were used to detect changes in secondary structure of plasminogen after EACA addition. Change in bovine plasminogen tertiary structure was determined by comparing ratios of amide II (1600–1500 cm−1) to amide I bond intensities over time for samples in deuterium. No differences in secondary structure were observed for any plasminogen in the presence of EACA; however, addition of EACA significantly changed tertiary structure of bovine plasminogen. This tertiary structural change indicates a transition from a folded to an unfolded state, which could be more easily converted to plasmin. These results are consistent with reported human plasminogen studies using neutron scattering (tertiary structure) and circular dichroism (secondary structure) methods.

The role of iron and the factors affecting off-color development of polyphenols

Iron deficiency affects over two billion people worldwide (Lotfi, M.; Venkatesh Mannar, M. G.; Merx, R. J.; Naber-van den Heuvel, P. Micronutrient Fortification of Foods: Current Practices, Research,and Opportunities; Micronutrient Initiative: Ottawa, Ontario, Canada, 1996). However, fortifying foods with highly bioavailable iron is technically challenging because of off-color and off-flavor development, catalytic degradation of vitamins, and oxidation of lipids. The role of highly bioavailable iron in the off-color development of foods and beverages is not well-understood. The goal of this research was to examine the interaction of iron with simple phenolics and polyphenols. Factors that may affect off-color development, such as pH, oxygen, temperature, and reducing and chelating agents, were evaluated as a model for food products. Our results demonstrated that the iron that reacts with the simple phenolic, catechol, to develop off-color must be in the oxidized state, and the iron is reduced in the presence of catechol. Because this is an oxidation/reduction reaction, the redox potential of all of the components is critical to the color development. Ferrous iron sources with low redox potentials and ferric iron sources with high redox potentials caused off-color development with catechol. Only polyphenols that contain ortho-hydroxyl groups cause off-color development with iron. All of the factors tested affect off-color development and redox potential of the system. Low pH, low oxygen, high temperature, and the presence of reducing and chelating agents inhibited off-color development. To confirm the model, foods that contained these polyphenols were evaluated for off-color development when iron was added. The foods tested reacted similarly to the models of polyphenols with iron. Off-color development was caused by oxidation-reduction interactions between ferric iron and polyphenols that contained ortho-dihydroxyl groups. Ferrous iron needed to be oxidized to participate in off-color development. In addition, methods identified in the models to prevent off-color development were effective in most of the food products examined. Using the ferrous form of iron and maintaining it in its reduced form by lowering pH, removing oxygen, and including reducing agents, it was possible to fortify foods with highly bioavailable iron.

Variation of the milk antibody response to paratuberculosis in naturally infected dairy cows

A longitudinal study was performed to determine the course of the milk antibody response in cows presumably infected with Mycobacterium avium subsp. paratuberculosis. Milk samples were collected repeatedly (1 to 10 times) from all lactating cows in seven Danish dairy herds. A total of 4,289 observations from 812 cows was analyzed after exclusion of samples collected after 280 days in milk (DIM). The level of antibodies in the milk samples was assessed using an indirect ELISA. A piece-wise linear random coefficient regression model was specified. The model controlled for the effect of herd, breed, laboratory effects, and age at first calving to estimate parity-specific antibody responses in relation to DIM. Separate antibody profiles were estimated for fecal culture-positive and fecal culture-negative cows. The resulting population average models showed higher antibody levels for fecal culture-positive cows and higher antibody levels with increasing parity. On average, the antibody response was high at the beginning and end of lactation. However, evaluating the cows individually indicated that most cows actually had quite stable ELISA levels throughout lactation, with some cows having higher levels than others. Thus, two criteria seem applicable to assess whether a cow is infected: stability and ELISA level. The random coefficients for each cow were highly significant. Thus, the study suggests that all cows can be classified into one of the four categories by combining the cow-level ELISA characteristics "stability" and "level" as an aid in the diagnosis ofparatuberculosis and thereby substantially increasing the sensitivity of the ELISA.

Plasmin system and microbial proteases in milk: characteristics, roles, and relationship

Proteolysis of milk proteins can be attributed to both native proteases and the proteases produced by psychrotrophic bacteria during storage of fresh raw milk. These proteases cause beneficial or detrimental changes, depending on the specific milk product. Plasmin, the major native protease in milk, is important for cheese ripening. Milk storage and cheese-making conditions can affect the level of plasmin in the casein and whey fractions of milk. A microbial protease from a psychrotrophic microorganism can indirectly increase plasmin levels in the casein curd. This relationship between the plasmin system and microbial proteases in milk provides a means to control levels of plasmin to benefit the quality of dairy products. This paper is a short review of both the plasmin system and microbial proteases, focusing on their characteristics and relationship and how the quality of dairy products is affected by their proteolysis of milk proteins.

Variance components of an enzyme-linked immunosorbent assay for detection of IgG antibodies in milk samples to Mycobacterium avium subspecies paratuberculosis in dairy cattle

Milk samples from 120 cows were tested up to 10 times in an enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Mycobacterium avium ssp. paratuberculosis. The purpose of the study was to estimate variance components of the assay attributable to laboratory factors using mixed model theory. Because of significant interaction between the between-run, between-day and between-plate variables, the ELISA-plate variable was nested in run-number and run-number was nested in day-number. The nested variable accounted for 68% of the laboratory variability (P < 0.001), whereas the intraplate variability accounted for only 0.04% of the laboratory variability (P > 0.9). Therefore, it was concluded that the intraplate variability could be ignored whereas the variability from the combined run-day-plate variable should be considered in any analyses based on the ELISA.

Patients with ovarian cancer have elevated (51)Cr-EDTA plasma clearance early post-operatively

Plasma clearance of (51)Cr-EDTA (Clp(EDTA)) is widely used to determine glomerular filtration rate prior to carboplatin based chemotherapy. We have observed that many patients with ovarian cancer have elevated Clp in the early post-operative phase compared to later phases. The purpose of this study was to examine whether this observation reflects a systematic difference. We retrospectively analysed data from 53 patients who had undergone surgery for ovarian cancer. Twenty-six patients had Clp(EDTA) measured early after the operation (mean, 8 days (range, 3-16 days)) (early group), and 27 patients had Clp(EDTA) measured late post-operatively (mean, 32 days (range, 19-48 days)) (late group). Clp(EDTA) values was measured before the first, third and fifth course of chemotherapy. Additionally, age, height, weight, cancer stage, ascites and tumour histology were noted. Mean Clp(EDTA) in the early group was significantly higher than in the late group (104+/-4.4 vs 89+/-3.5 ml.min(-1) per 1.73 m(2); P =0.005). Clp(EDTA) declined significantly in the early group from the first measurement after the operation until measurement before the third course of chemotherapy but remained constant in the late group. Clp(EDTA) was not correlated to ascites, cancer stage or tumour histology. It is concluded that patients with ovarian cancer have significantly higher Clp(EDTA) in the early post-operative phase than similar patients with Clp(EDTA) measured late post-operatively.