An enzyme linked immunosorbent assay was developed for the detection of immunoglobulin class specific antibodies to Leptospira interrogans serovar pomona in the serum and aqueous humor of horses. Serum antibody was also assayed by microscopic agglutination tests. Although higher levels of antibody were found in sera from horses with signs of uveitis, the association was not statistically significant. Antibodies to pomona were detected in the aqueous of 12 eyes from the 101 horses sampled at a slaughterhouse, and in most instances, a comparison of the aqueous/serum antibody level with that of the total aqueous/serum IgG level indicated intraocular antibody synthesis. Antibodies were also found in 4 aqueous (or vitreous) samples out of 9 obtained from horses with clinically documented uveitis and the above comparison again indicated intraocular antibody synthesis. The data point to an important role for pomona as an etiology of equine recurrent uveitis but also emphasize that the initiating cause for this disease is often obscure in that association with leptospirosis cannot be shown in many instances.
To identify the cell types which produce BMP and TGF-beta during fracture healing and to elucidate the interactions between BMP and TGF-beta in regulating cell proliferation and differentiation at various stages, an experimental model of fracture healing in the rabbit mandible was established and the expression of BMP-2 and TGF-beta 1 mRNA was studied at different healing stages by in situ hybridization. The results showed that undifferentiated mesenchymal cells, differentiating osteoblasts and chondroblasts, had higher levels of BMP-2 mRNA at the stage of intramembranous bone formation and early chondrogenesis, while the level of TGF-beta 1 mRNA was higher in chondrocytes and active differentiated osteoblasts during chondrogenesis and endochondral ossification, respectively. We conclude that BMP-2 expression was correlated with the differentiation of mesenchymal cells into osteoblasts and chondrocytes. TGF-beta 1 mRNA expression was closely associated with the active synthetic stage of osteoblasts and chondrocytes. These observations suggest that both BMP and TGF-beta are involved in the regulation of fracture healing. BMP may play an important role in bone induction and early chondrogenesis, while TGF-beta regulates the proliferation and active synthetic ability of chondrocytes and osteoblasts.
SUMMARY
This paper provides additional experimental evidence that biological variation between individuals is likely to be the major factor influencing the overall precision and efficiency of nested sampling schemes for morphometric analysis of thin sections.
Four distinct experimental systems (two based on nervous tissue and two on epithelia) have been investigated. Morphometric estimates were obtained from measurements made on micrographs generated by sampling tissues at several levels. Sources of sampling variation were isolated so that the contributions to overall variance made by inter‐animal differences could be evaluated.
In each case, biological variation was the cardinal component of total observed variance between animals. Relative contributions ranged from 53% to 78%. Examining more animals would be the most efficient way of reducing the variance of the group mean in these sampling designs.
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