Note on Confidence Regions in Multiple Assays

This note is in continuation of the author's results on ’classical‘ confidence regions for relative potencies in multiple assays (Bennett, 1987). It is shown by the use of a Bonferroni inequality (e.g. Miller, ch. 2, 1980) that approximate confidence regions for the relative potencies {M_i} i = 1, …, p may also be obtained directly. A comparison with the classical regions is made for the case: p = 2 using Finney's example (1978, ch. 2).     

Across-subject calibration of an instrumented glove to measure hand movement for clinical purposes

Motion capture of all degrees of freedom of the hand collected during performance of daily living activities remains challenging. Instrumented gloves are an attractive option because of their higher ease of use. However, subject-specific calibration of gloves is lengthy and has limitations for individuals with disabilities. Here, a calibration procedure is presented, consisting in the recording of just a simple hand position so as to allow capture of the kinematics of 16 hand joints during daily life activities even in case of severe injured hands. ‘across-subject gains’ were obtained by averaging the gains obtained from a detailed subject-specific calibration involving 44 registrations that was repeated three times on multiple days to 6 subjects. In additional 4 subjects, joint angles that resulted from applying the ‘across-subject calibration’ or the subject-specific calibration were compared. Global errors associated with the ‘across-subject calibration’ relative to the detailed, subject-specific protocol were small (bias: 0.49°; precision: 4.45°) and comparable to those that resulted from repeating the detailed protocol with the same subject on multiple days (0.36°; 3.50°). Furthermore, in one subject, performance of the ‘across-subject calibration’ was directly compared to another fast calibration method, expressed relative to a videogrammetric protocol as a gold-standard, yielding better results.     

Multi-dimensional correlative imaging of subcellular events: combining the strengths of light and electron microscopy

To genuinely understand how complex biological structures function, we must integrate knowledge of their dynamic behavior and of their molecular machinery. The combined use of light or laser microscopy and electron microscopy has become increasingly important to our understanding of the structure and function of cells and tissues at the molecular level. Such a combination of two or more different microscopy techniques, preferably with different spatial- and temporal-resolution limits, is often referred to as ‘correlative microscopy’. Correlative imaging allows researchers to gain additional novel structure–function information, and such information provides a greater degree of confidence about the structures of interest because observations from one method can be compared to those from the other method(s). This is the strength of correlative (or ‘combined’) microscopy, especially when it is combined with combinatorial or non-combinatorial labeling approaches. In this topical review, we provide a brief historical perspective of correlative microscopy and an in-depth overview of correlative sample-preparation and imaging methods presently available, including future perspectives on the trend towards integrative microscopy and microanalysis.     

Evaluation of distribution-free confidence limits for enzyme kinetic parameters

Monte Carlo experiments have been used to test the robustness of distribution-free confidence limits for the parameters of the Michaelis-Menten equation (Porter & Trager, 1977). When used in conjunction with the modified form of the direct linear plot (Cornish-Bowden & Eisenthal, 1978), they prove to be more robust than least-squares confidence limits. In circumstances where the least-squares assumptions are correct, the distribution-free confidence limits define the parameters somewhat less precisely than the corresponding least-squares confidence limits, but this effect is negligible unless there are eight or fewer observations.     

Crystal structure of subtilisin complexed with its trapped substrateStreptomyces subtilisin inhibitor—Protein-protein interaction and evolution of serine proteinases and their proteinaceous inhibitors

The complex of a bacterial alkaline serine proteinase, subtilisin BPN’, with its proteinaceous inhibitorStreptomyces subtilisin inhibitor is unique in several respects, compared with other similar complexes containing serine proteinases of trypsin family. In addition to the usual antiparallelβ-sheet involving P₁-P₃ residues of the inhibitor, P₄-P₆ residues form antiparallelβ-sheet with a previously unnoticed chain segment (the ‘S4-6 site’) of subtilisin. The ‘S4-6 site’ does not exist in serine proteinases of trypsin family, whether of mammalian or microbial origin. Global induced-fit movement seems to occur on the ‘trapped substrate’Streptomyces subtilisin inhibitor: a channel-like structure in SSI remote from the contact region becomes about 2 Å wider upon complexing with subtilisin. Main role of the secondary contact region ofStreptomyces subtilisin inhibitor seems to support the reactive site loop (primary contact region). Steric homology for the two contact regions is so high between the inhibitors ofStreptomyces subtilisin inhibitor family and those of pancreatic secretory trypsin inhibitor-ovomucoid inhibitor family that it seems to favour a divergent evolution and to support the general notion as to the relationship of prokaryotic and eukaryotic genes put forwarded by Doolittle(Nature (London),272, 581, 1978).     

Cytodiagnosis through use of a z‐axis video by volunteer observers: a promising tool for external quality assessment

K. Yamashiro, M. Tagami, K. Azuma, A. Nakamura, O. Kato, K. Taira, M. Azuma, H. Takeda and H. Suzuki Cytodiagnosis through use of a z‐axis video by volunteer observers: a promising tool for external quality assessment Objective: This study examined whether cytological diagnosis through the use of a video, which shows the changing depth of focus in the microscopic field, described as a z‐axis video, is useful compared with a still image. Methods: From 17 cytology preparations of fine needle aspiration of the breast, we made six z‐axis videos per case. A frame exhibiting the characteristic features was then extracted from each video and saved as a representative still image. One hundred and twenty‐eight volunteer cytotechnologists were randomly divided into two groups of video observers and still image observers. The participants were asked to make a diagnosis of benign, indeterminate, suspicious or malignant without having any clinical information other than the age of the patient. Diagnoses were categorized as ‘recommended’ or ‘unacceptable’ according to degree of correlation with histology. Results: The number of definitive diagnoses of ‘benign’ or ‘malignant’ were increased in video observers, and indeterminate or suspicious categories were decreased (P = 0.013). The distribution of diagnostic categories in three of the 17 cases was significantly different; the distribution in the remaining cases was similar between the two groups. The z‐axis video observers may have selected the definite diagnoses with confidence because they observed valuable microscopic findings by ‘focusing through observation’. The average number of ‘recommended’ diagnoses by individual observers was significantly higher in the video observer group than in the still image observer group (P = 0.016). In contrast, the average number of ‘unacceptable’ diagnoses was significantly lower (P = 0.019). Conclusions: A z‐axis video is easy to obtain and is therefore expected to become a powerful diagnostic modality for the external quality assessment of clinical cytology and even in the field of primary cytodiagnosis.     

Reconsideration of the derivation of Most Probable Numbers,their standard deviations,confidence bounds and rarity values

Aims: The purpose of this work was to derive a simple Excel spreadsheet and a set of standard tables of most probable number (MPN) values that can be applied by users of International Standard Methods to obtain the same output values for MPN, SD of the MPN, 95% confidence limits and test validity. With respect to the latter, it is considered that the Blodgett concept of ‘rarity’ is more valuable than the frequently used approach of improbability (vide de Man). Methods and Results: The paper describes the statistical procedures used in the work and the reasons for introducing a new set of conceptual and practical approaches to the determination of MPNs and their parameters. Examples of MPNs derived using these procedures are provided. The Excel spreadsheet can be downloaded from http://www.wiwiss.fu‐berlin.de/institute/iso/mitarbeiter/wilrich/index.html . Conclusions: The application of the revised approach to the determination of MPN parameters permits those who wish to use tabulated values, and those who require access to a simple spreadsheet to determine values for nonstandard test protocols, to obtain the same output values for any specific set of multiple test results. The concept of ‘rarity’ is a more easily understood parameter to describe test result combinations that are not statistically valid. Provision of the SD of the log MPN value permits derivation of uncertainty parameters that have not previously been possible. Significance and Impact of the Study: A consistent approach for the derivation of MPNs and their parameters is essential for coherence between International Standard Methods. It is intended that future microbiology standard methods will be based on the procedures described in this paper.     

Some aspects of the host:parasite relationships between adult blackflies (Diptera; Simuliidae) and larvae of the water-mite Sperchon setiger(Acari; Hydrachnellae) in a small chalk stream in southern England

SUMMARY. In Bere Stream three species of adult simuliids, S . ornatum, S. equinum and S. angustipes were parasitized by Sperchon setiger larvae. Trapped adult S. ornatum were more often parasitized than corresponding adults of S. equinum. The lower 95% confidence limits were used as an indication of the relative importance of the statistically significant differences and were high (10.4–33.6%). Laboratory experiments on the occupation of host pupae by pre-parasitic Sperchon setiger larvae also indicated that pupae of S. ornatum were more often occupied than S. equinum. This was confirmed by tests on the difference in percentage occupation of more than 4000 held-collected host pupae. In tests that indicated a significant difference in percentage parasitization between the sexes of the three host species, females were more often parasitized. However, the lower 95% confidence limits for the increase in percentage parasitization of females compared to males were low (0.9–10.2%). The majority of adult simuliids carried only one parasite. The mean number of larvae per trapped parasitized host was significantly greater for S. ornatum (2.69) than for S. equinum (1.77). There was no significant difference between the mean number of parasites carried by the sexes of S. ornatum for each year from 1975 through 1978 but females were significantly more heavily parasitized than males during 1979. The ventral neck region of all three host species is the main attachment site for Sperchon setiger larvae.
The morphology of the pupae of S. ornatum and S. equinum is related to differences in levels of percentage parasitization between these two species. It is suggested that pupal morphology may be the most important factor in the selection of host simuliids by Sperchon setiger larvae.     

Racism,disadvantage and multiculturalism: towards effective anti-racist praxis

Measuring ethnicity in any society is a challenge. Given world immigration patterns, many countries face a growing dilemma in determining the cultural antecedents of their populations. A further complication is the reality that such determination occurs within the political and nationalistic settings where ethnic‐cultural groups may be potent forces in their own right. As societies mature and evolve, there is an increasing tendency for populations, especially those with many generations of residence in the country, to see themselves as ‘indigenous’ to the society in which they live. Canada is not alone in having to deal with the fluidity of the concept, ‘Canadian’, ‘American’, ‘Australian’, ‘Yugoslav’, and ‘Soviet’ are parallel concepts in other countries of multiple ethnic composition. Using 1991 National Census Test results, the article explores some of the parameters of the indigenous category ‘Canadian’. In particular, the location in Canada and mother tongue of respondents reporting ‘Canadian’ as the ethnic origin of their parents and grandparents or as their own ethnic identity are important indicators for this emerging ethnic category.     

A repeatable and quantitative DNA metabarcoding assay to characterize mixed strongyle infections in horses

Horses are ubiquitously infected by a diversity of gastro-intestinal parasitic helminths. Of particular importance are nematodes of the family Strongylidae, which can significantly impact horse health and performance. However, knowledge about equine strongyles remains limited due to our inability to identify most species non-invasively using traditional morphological techniques. We developed a new internal transcribed spacer 2 (ITS2) DNA metabarcoding ‘nemabiome’ assay to characterise mixed strongyle infections in horses and assessed its performance by applying it to pools of infective larvae from fecal samples from an experimental herd in Kentucky, USA and two feral horse populations from Sable Island and Alberta, Canada. In addition to reporting the detection of 33 different species with high confidence, we illustrate the assay’s repeatability by comparing results generated from aliquots from the same fecal samples and from individual horses sampled repeatedly over multiple days or months. We also validate the quantitative potential of the assay by demonstrating that the proportion of amplicon reads assigned to different species scales linearly with the number of larvae present. This new tool significantly improves equine strongyle diagnostics, presenting opportunities for research on species-specific anthelmintic resistance and the causes and consequences of variation in mixed infections.     

The saltmarshes of Coll and Tiree

Summary

A survey was made of the saltmarshes of the Inner Hebridean islands of Coll and Tiree. Seventeen plant communities are described and classified using the National Vegetation Classification (NVC). The saltmarshes are compared with those described from elsewhere in the region, and from other parts of Britain, and their species composition and range of communities place them firmly within the Type C — ‘western Scottish’ — marsh type described by Adam (1978). The islands support several saltmarsh communities and species of considerable phytogeographical and nature conservation importance.     

Epizootic cutaneous papillomatosis in roach Rutilus rutilus: sex and size dependence,seasonal occurrence and between-population differences

Validation of a single round PCR-based assay to confirm as Myxobolus cerebralis myxospores obtained from pepsin-trypsin digest preparations is described. The assay is a modification of a PCR assay published previously, based on the amplification of a segment of the gene encoding the 18S ribosomal subunit of M. cerebralis. The sensitivity, specificity and upper and lower detection limits were determined using known M. cerebralis and non-M. cerebralis myxospores and M. cerebralis-free fish. The sensitivity of PCR confirmation was 100% (95% confidence interval of 83.2-100%). The specificity was 100% (95% confidence interval of 87.2-100%). The upper detection limit was approximately 100,000 myxospores per reaction; the lower detection limit was approximately 50 myxospores per reaction. Given the high sensitivity and specificity of the assay, substitution of this assay for histologic confirmation of M. cerebralis infection is encouraged.     

Why are most EU pigs tail docked? Economic and ethical analysis of four pig housing and management scenarios in the light of EU legislation and animal welfare outcomes

To limit tail biting incidence, most pig producers in Europe tail dock their piglets. This is despite EU Council Directive 2008/120/EC banning routine tail docking and allowing it only as a last resort. The paper aims to understand what it takes to fulfil the intentions of the Directive by examining economic results of four management and housing scenarios, and by discussing their consequences for animal welfare in the light of legal and ethical considerations. The four scenarios compared are: ‘Standard Docked’, a conventional housing scenario with tail docking meeting the recommendations for Danish production (0.7 m²/pig); ‘Standard Undocked’, which is the same as ‘Standard Docked’ but with no tail docking, ‘Efficient Undocked’ and ‘Enhanced Undocked’, which have increased solid floor area (0.9 and 1.0 m²/pig, respectively) provision of loose manipulable materials (100 and 200 g/straw per pig per day) and no tail docking. A decision tree model based on data from Danish and Finnish pig production suggests that Standard Docked provides the highest economic gross margin with the least tail biting. Given our assumptions, Enhanced Undocked is the least economic, although Efficient Undocked is better economically and both result in a lower incidence of tail biting than Standard Undocked but higher than Standard Docked. For a pig, being bitten is worse for welfare (repeated pain, risk of infections) than being docked, but to compare welfare consequences at a farm level means considering the number of affected pigs. Because of the high levels of biting in Standard Undocked, it has on average inferior welfare to Standard Docked, whereas the comparison of Standard Docked and Enhanced (or Efficient) Undocked is more difficult. In Enhanced (or Efficient) Undocked, more pigs than in Standard Docked suffer from being tail bitten, whereas all the pigs avoid the acute pain of docking endured by the pigs in Standard Docked. We illustrate and discuss this ethical balance using numbers derived from the above-mentioned data. We discuss our results in the light of the EU Directive and its adoption and enforcement by Member States. Widespread use of tail docking seems to be accepted, mainly because the alternative steps that producers are required to take before resorting to it are not specified in detail. By tail docking, producers are acting in their own best interests. We suggest that for the practice of tail docking to be terminated in a way that benefits animal welfare, changes in the way pigs are housed and managed may first be required.     

Differential colonization of wheat cultivars by two biotypes of Russian wheat aphid （Homoptera： Aphididae）

Susceptible and resistance wheat cultivars, Triticum aestivum L, were presented to two biotypes of Russian wheat aphid, Diuraphis noxia （Mordvilko）, in multiple choice tests to assay their relative acceptability as host plants. Both apterae （third and fourth instars） and alate adults were offered plants at the two-leaf stage in different cultivar combinations at 22±1℃ and 16：8 （L： D） hour photoperiod. Apterae were released from Petri dishes in the center of a circle of test plants, whereas alatae dispersed from a mature aphid colony to settle on plants arranged in rows. Both alatae and apterous nymphs of both biotypes readily colonized all cultivars tested：‘2137＇, ‘Akron＇,‘Ankor’,‘ Halt’ ,‘ Jagger’ ,‘ Prairie Red’ , ‘Stanton＇,‘TAM 107＇,‘TAM 110＇,‘Trego＇, ‘ Yuma＇, and ‘Yumar＇. Fewer biotype I apterae responded （settled and fed） in the combination containing more resistant （Dn4- and Dny-expressing） cultivars, compared to the combinations that had fewer. The reverse was true for biotype 2 apterae; more aphids responded in the combination containing the largest number of Dn4 expressing cultivars. Differential colonization of cultivars was observed in only one combination, in which biotype 2 apterae colonized Akron and Yumar in larger numbers than they did Stanton and Yuma. A separate experiment confirmed that, 48 hours after infestation, more biotype 2 apterae abandoned plants of Yuma than plants of Yumar. This differential response was likely due to genetic differences between the two ＇ near isogenic＇ lines that include the lack of Dn4 expression in Yuma. Choice tests with alatae did not result in differential rates of cultivar colonization by either biotype in any combination tested. These results suggest that young wheat plants appear to lack any meaningful antixenosis toward D. noxia, even though the aphids appear to perceive, and sometimes respond to, certain differences in cultivar suitability.     

Ante-mortem detection of chronic wasting disease in recto-anal mucosa-associated lymphoid tissues from elk (Cervus elaphus nelsoni) using real-time quaking-induced conversion (RT-QuIC) assay: A blinded collaborative study

Prion diseases are transmissible spongiform encephalopathies (TSEs) characterized by fatal, progressive neurologic diseases with prolonged incubation periods and an accumulation of infectious misfolded prion proteins. Antemortem diagnosis is often difficult due to a long asymptomatic incubation period, differences in the pathogenesis of different prions, and the presence of very low levels of infectious prion in easily accessible samples. Chronic wasting disease (CWD) is a TSE affecting both wild and captive populations of cervids, including mule deer, white-tailed deer, elk, moose, muntjac, and most recently, wild reindeer. This study represents a well-controlled evaluation of a newly developed real-time quaking-induced conversion (RT-QuIC) assay as a potential CWD diagnostic screening test using rectal biopsy sections from a depopulated elk herd. We evaluated 69 blinded samples of recto-anal mucosa-associated lymphoid tissue (RAMALT) obtained from USDA Veterinary Services. The results were later un-blinded and statistically compared to immunohistochemical (IHC) results from the USDA National Veterinary Services Laboratories (NVSL) for RAMALT, obex, and medial retropharyngeal lymph node (MRPLN). Comparison of RAMALT RT-QuIC assay results with the IHC results of RAMALT revealed 92% relative sensitivity (95% confidence limits: 61.52–99.8%) and 95% relative specificity (95% confidence limits: 85.13–99%). Collectively, our results show a potential utility of the RT-QuIC assay to advance the development of a rapid, sensitive, and specific prion diagnostic assay for CWD prions.     

Multivariate slope ratio assay with repeated measurements

A method is given for analyzing a slope ratio assay in which a test drug is compared with a standard drug, two or more response variates being measured on each subject at each of several successively increased drug doses. The method requires all subjects to receive the same number of doses, all subjects on the same drug to receive the same doses, the ratio of corresponding doses of the two drugs to be constant over the successive increases, and response variables to be measured only once on each subject at each dose with no missing data allowed. The technique is also applicable when doses are randomly assigned, provided there is no carry-over effect between doses. For each of the J response variates, the relative potency of the test drug with respect to the standard is defined and estimated in the usual way; a 100(1-alpha)% confidence region is then obtained for the vector of the J relative potencies. A procedure is given for testing the equality of some or all of the J relative potencies; an estimator of a common relative potency is obtained by a standard multivariate least squares method. A common relative potency is of interest because the multiple outcome variables are often different indicators of a general physiologic response. The procedures in the paper are illustrated by a simple example concerning the effects of two anesthetics on children.     

Univariate Dose-Response Models in Case-Control Studies

For modelling dose-response relationships in case-control studies the multiplicative logistic regression model, assuming the relative risk to be an exponential function of the dose, is widely known. If the relative risk is assumed to be a linear function of the dose, several authors (see e.g. BERRY (1980)) have proposed an additive (linear) model. This model has a better fit with the data if such a linear relation holds. Confidence limits for the relative risk derived from the information matrix, however, appear to be rather inaccurate. Therefore, use of the ‘standard’ logistic model in two different ways was studied: extension with a quadratic term or a logarithmic transformation of the dose. By applying the methods both to an empirical data set and in a simulation experiment, it is shown that appropriate transformation (often logarithmic) of the dosage and then applying the ‘standard’ logistic model is an useful approach if a linear dose-response relationship holds.     

Effects of endogenous hormones on variation of shoot branching in a variety of non-heading Chinese cabbage and related gene expression

Shoot branching (tillering) primarily determines plant shoot architecture and has been studied in many plants. Shoot branching is an important trait in non-heading Chinese cabbage (Brassica rapa ssp. chinensis Makino). The B. rapa ssp. chinensis var. multiceps exhibits unique and multiple shoot branching characteristics. Here, we analyzed the variation in shoot branching between ‘Maertou,’ with multiple shoot branching, and ‘Suzhouqing,’ a common variety. The levels of endogenous indole-3-acetic acid (IAA), zeatin riboside and active gibberellins in the shoot meristem tissues of the two cultivars were quantified by enzyme-linked immunosorbent assay during the vegetative growth stage. High levels of IAA maintained axillary bud dormancy and repressed axillary bud outgrowth allowing shoot branching to form in the vegetative stage in ‘Suzhouqing.’ In contrast, low levels of IAA did not inhibit axillary buds in ‘Maertou,’ while a high level of cytokinin promoted axillary bud growth and branch shoot development. Exogenous hormone (rac-GR24 and 6-benzylaminopurine) treatment showed that ‘Maertou’ was relatively sensitive to cytokinin, because the fold changes of cytokinin-responsive genes in ‘Maertou’ were significantly more frequent than those in ‘Suzhouqing’. Cytokinin was the direct regulator for axillary bud growth of ‘Maertou’. Compared with ‘Suzhouqing’, ‘Maertou’ was sensitive to cytokinin and this weakened the strigolactone–cytokinin branching pathway.     

CD73 activity of mesenchymal stromal cell-derived extracellular vesicle preparations is detergent-resistant and does not correlate with immunomodulatory capabilities

Background aimsExtracellular vesicles (EVs) derived from human mesenchymal stromal cells (MSCs) show immunomodulatory activity in different assays both in vitro and in vivo. In previous work, the authors compared the immunomodulatory potential of independent MSC-EV preparations in a multi-donor mixed lymphocyte reaction (mdMLR) assay and an optimized steroid-refractory acute graft-versus-host disease (aGVHD) mouse model. The authors observed that only a proportion of the MSC-EV preparations showed immunomodulatory capabilities and demonstrated that only MSC-EV preparations with mdMLR immunomodulating activities were able to suppress aGVHD symptoms in vivo and vice versa. Since the mdMLR assay is complex and depends on primary human cells of different donors, the authors sought to establish an assay that is much easier to standardize and fulfills the requirements for becoming qualified as a potency assay.MethodsThe bona fide MSC antigen CD73 possesses ecto-5’-nucleotidase activity that cleaves pro-inflammatory extracellular adenosine monophosphate into anti-inflammatory adenosine and free phosphate. To test whether the ecto-5’-nucleotidase activity of the MSC-EV preparations reflected their immunomodulatory potential, the authors adopted an enzymatic assay that monitors the ecto-5’-nucleotidase activity of CD73 in a quantitative manner and compared the activity of well-characterized MSC-EV preparations containing or lacking mdMLR immunomodulatory activity.ResultsThe authors showed that the ecto-5’-nucleotidase activity of the MSC-EV preparations did not correlate with their ability to modulate T-cell responses in the mdMLR assay and thus with their potency in improving disease symptomatology in the optimized mouse aGVHD model. Furthermore, the ecto-5’-nucleotidase activity was resistant to EV-destroying detergent treatment.ConclusionsEcto-5’-nucleotidase activity neither reflects the potency of the authors’ MSC-EV preparations nor provides any information about the integrity of the respective EVs. Thus, ecto-5’-nucleotidase enzyme activity is not indicative for the immunomodulatory potency of the authors’ MSC-EV products. The development of appropriate potency assays for MSC-EV products remains challenging.     

Development and comparison of two assay formats for parallel detection of four biothreat pathogens by using suspension microarrays

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple pathogens. We developed diagnostic suspension microarrays for sensitive and specific detection of the biothreat pathogens Bacillus anthracis, Yersinia pestis, Francisella tularensis and Coxiella burnetii. Two assay chemistries for amplification and labeling were developed, one method using direct hybridization and the other using target-specific primer extension, combined with hybridization to universal arrays. Asymmetric PCR products for both assay chemistries were produced by using a multiplex asymmetric PCR amplifying 16 DNA signatures (16-plex). The performances of both assay chemistries were compared and their advantages and disadvantages are discussed. The developed microarrays detected multiple signature sequences and an internal control which made it possible to confidently identify the targeted pathogens and assess their virulence potential. The microarrays were highly specific and detected various strains of the targeted pathogens. Detection limits for the different pathogen signatures were similar or slightly higher compared to real-time PCR. Probit analysis showed that even a few genomic copies could be detected with 95% confidence. The microarrays detected DNA from different pathogens mixed in different ratios and from spiked or naturally contaminated samples. The assays that were developed have a potential for application in surveillance and diagnostics.