Faculty Bibliography

Brain registration to a stereotaxic atlas is an effective way to report anatomic locations of interest and to perform anatomic quantification. However, existing stereotaxic atlases lack comprehensive coordinate information about white matter structures. In this paper, white matter-specific atlases in stereotaxic coordinates are introduced. As a reference template, the widely used ICBM-152 was used. The atlas contains fiber orientation maps and hand-segmented white matter parcellation maps based on diffusion tensor imaging (DTI). Registration accuracy by linear and non-linear transformation was measured, and automated template-based white matter parcellation was tested. The results showed a high correlation between the manual ROI-based and the automated approaches for normal adult populations. The atlases are freely available and believed to be a useful resource as a target template and for automated parcellation methods.

Diffusion tensor imaging (DTI) is an exciting new MRI modality that can reveal detailed anatomy of the white matter. DTI also allows us to approximate the 3D trajectories of major white matter bundles. By combining the identified tract coordinates with various types of MR parameter maps, such as T2 and diffusion properties, we can perform tract-specific analysis of these parameters. Unfortunately, 3D tract reconstruction is marred by noise, partial volume effects, and complicated axonal structures. Furthermore, changes in diffusion anisotropy under pathological conditions could alter the results of 3D tract reconstruction. In this study, we created a white matter parcellation atlas based on probabilistic maps of 11 major white matter tracts derived from the DTI data from 28 normal subjects. Using these probabilistic maps, automated tract-specific quantification of fractional anisotropy and mean diffusivity were performed. Excellent correlation was found between the automated and the individual tractography-based results. This tool allows efficient initial screening of the status of multiple white matter tracts.

Intermittent parathyroid hormone (PTH) administration increases bone formation and bone mass and is being used as a therapy for osteoporosis. By contrast, chronic hyperparathyroidism results in the metabolic bone disease osteitis fibrosa characterized by local bone resorption and peritrabecular bone marrow fibrosis in humans. The animal models that can mimic the paradoxical effects of PTH provide the basis for further study of the functions of this hormone in skeletal tissues. In both rats and mice, the anabolic effects of PTH on bone can be achieved by daily injections subcutaneously and the catabolic effects can be achieved by continuous infusion with osmotic pumps. This chapter offers detailed information, such as the dosage and preparation of PTH, using the example of treatment of rats with PTH intermittently or continuously. High-quality, RT-PCR ready RNA is required for the analysis of gene expression. For the analysis of gene expression in bone, usually long bones are used for RNA extraction. Here we describe how to extract RNAs from the metaphyseal trabecular primary spongiosa of rat femur by a method based on two commercially available kits. This protocol can be used in other tissues with slight modification of the amount of reagent used according to the tissue size.

A polydnavirus (PDV) was purified by sucrose density gradient centrifugation from the calyx region of female parasitoid wasp Microplitis mediator (Hymenoptera: Braconidae). Negative stain technique showed that the virus was tadpole-like and measured 130 X 35nm. A diverse protein profile of the virus' capsid proteins was displayed by SDS-PAGE. Its genome was composed of over 14 DNA molecules, which were different in molecular size and abundance. Molecular size of the genome was approximate 108 kbp calculated by patterns from six restrict endonucleases digestion. Micro-injection experiment with calyx fluid of the female wasps showed that the virus suppressed growth and development of host of the wash.