Design and fabrication of topologically complex, three-dimensional microstructures

Two concepts for use in the fabrication of three-dimensional (3D) microstructures with complex topologies are described. Both routes begin with a two-dimensional (2D) pattern and transform it into a 3D microstructure. The concepts are illustrated by use of soft lithographic techniques to transfer 2D patterns to cylindrical (pseudo-3D) substrates. Subsequent steps-application of uniaxial strain, connection of patterns on intersecting surfaces-transform these patterns into free-standing, 3D, noncylindrically symmetrical microstructures. Microelectrodeposition provides an additive method that strengthens thin metal designs produced by patterning, welds nonconnected structures, and enables the high-strain deformations required in one method to be carried out successfully.     

Salmonella Dublin infection in Queensland dairy cattle

Objective: To investigate the presence of Salmonella Dublin in Queensland cattle.
Design: An epidemiological study using diagnostic laboratory information and farm records.
Procedure: Outbreaks of gastroenteritis or pneumonia in calves, and abortions and enteritis in cows were routinely investigated for the presence of salmonellae. Where S Dublin was isolated, attempts were made to gather further epidemiological information.
Results: Prior to 1983 only two outbreaks of S Dublin have been recorded in Queensland dairy cattle. In 1983 S Dublin abortions were diagnosed in dairy heifers introduced from southern Australia to south-east Queensland. Sampling indicated that at least 10% of the 500 introduced heifers were faecal excretors of S Dublin. On 3 of the 7 farms from which S Dublin was recorded, infection spread to other cattle that were in contact. From February 1985 to February 1996, 29 outbreaks of S Dublin in cattle occurred on 29 farms (28 in south east Queensland and 1 in north Queensland). Calves were primarily affected. Continuing outbreaks were confirmed on only 4 of these 29 farms. On 15 farms S Dublin infections were associated with the purchase of infected calves or cows, while another farm adjoined 2 previously infected farms. No source of S Dublin was evident for the other 13 farms, where histories were often inadequate.
Conclusion: There has been a marked increase in S Dublin outbreaks in Queensland dairy cattle since 1983. Introduction of S Dublin carrier and aborting dairy heifers from southern Australia, where S Dublin is not uncommon, was associated with the initial outbreaks.     

Monitoring and surveillance in abattoirs of residues of antibacterial substances – a description of programs in Australia and the USA

SUMMARY Australia and the USA are major international meat exporting countries. Both countries conduct programs to monitor and survey for antibacterial residues. Australian programs use a urine screening test, whereas the US programs use tissue fluids as the test medium. The development of surveillance programs to provide rapid feedback to producers is a feature of the Australian programs. The programs in each country compare favourably with regard to numbers of animals tested, results and action taken to prevent residues. The results of the Australian programs justify the promotion of a ‘clean food’ image for Australian meat products with respect to antibacterial drugs.     

Anthelmintic resistance in the field: Changes in resistance status of parasitic populations in response to anthelmintic treatment

Changes in anthelmintic resistance in nematode parasites were monitored in sheep grazing on 2 separate farms, but with the same anthelmintic treatment program, over 16 years. High levels of benzimidazole resistance emerged in Ostertagia and Trichostrongylus spp populations on both farms following 9 years of continuous use of this class of drug. Subsequently, variations in the levels of resistance occurred for the same species between farms and between species on the same farm. A change to levamisole for 2 years resulted in a significant reversion towards benzimidazole susceptibility, but a concomitant rise in levamisole resistance, in Ostertagia on one farm. However, benzimidazole resistance increased rapidly following the re-introduction of oxfendazole into the anthelmintic treatment program. Results from both farms illustrate the pitfalls of using one anthelmintic class for an extended period and provide indirect support for the alternation of anthelmintic classes at approximately yearly intervals.     

Pyrrolizidine alkaloidosis of cattle associated with Senecio lautu

Summary Serious incidents of pyrrolizidine alkaloidosis of cattle in 10 herds exposed to the Australian native plant, Senecio lautus (Asteraceae), were seen in central Queensland during 1988–1992. The deaths of 226 cattle were recorded. A mean of 8% of cattle died in affected groups (range 2 to 58%). Sickness and deaths usually occurred some months after access to S lautus. Typically, affected cattle lost body condition to the point of emaciation before dying and had persistent diarrhoea. Some animals developed abnormal behaviour and died after a shorter illness. Liver specimens from affected cattle in all herds contained lesions consistent with pyrrolizidine alkaloidosis. Thin layer chromatography of extracts of blood and liver samples from cattle from 5 herds detected pyrrolic metabolites. The identity of these was confirmed by mass spectroscopy on samples from one herd. Unseasonal autumn and winter rain after a dry summer appeared to favour growth of S lautus at the expense of other pasture species. A subsequent dry period promoted consumption of S lautus and was followed by a cluster of poisoning incidents.     

Antinucleolar antibody associated with lupus erythematosus in a dog

A nucleolar pattern of fluorescence was detected in an Antinuclear Antibody (ANA) test on serum of an 8-year-old Collie with Systemic Lupus Erythematosus (SLE). Skin disease characterized by a lymphoplasmacytic infiltrate and epidermal necrosis and a positive Coombs' test supported the diagnosis. The dog responded to immunosuppressive drugs and continues to do well on maintenance therapy.     

Porcine myelomonocytic markers: summary of the second international swine CD workshop

Forty five mAbs submitted to the Second International Swine CD workshop were analyzed by six different laboratories for their possible reactivity with porcine myelomonocytic cells using flow cytometry and immunohistochemistry. As a result of these analyses, a new swine workshop cluster, SWC9, composed of two mAbs that recognize an antigen selectively expressed on mature macrophages, was defined. In addition, several mAbs were identified, allowing the differentiation of granulocytes from monocytes/macrophages, or monocytes from macrophages. Further work is required to identify the antigen recognized by these mAbs. Nevertheless, they should already prove useful for the identification of different stages in the macrophage maturation/differentiation, and will certainly aid analyses on the complexity of the mononuclear phagocyte system in the pig. Finally, the cross-reactivity of three anti-human CD14 mAbs with porcine myelomonocytic cells was established in this workshop.