Use of apparent transverse quantitative ultrasonography to assess skeletal integrity in layers.

Although there are several techniques currently available to assess skeletal integrity in live birds, few offer important features for application in a commercial setting, offering ease of use and moderate cost. Quantitative ultrasonography (QUS) is an established technique for diagnosis of osteoporosis in humans and horses that has potential application for layers. An OmniSense 700S quantitative ultrasonometer was evaluated for use with Single Comb White Leghorn hens. Humeral QUS values (m/s) were measured in a series of experiments using a total of 144 Shaver White hens. Significant correlations (P < 0.01) were observed among sequential QUS measurements taken on the same bird at 54, 60, and 66 wk of age. At the completion of the studies (66 wk of age), the left and right humeri were excised, cleaned, and rescanned. Postmortem QUS data from left and right humeri were related (R2 = 0.72, P < 0.0001), although future studies may need to consider both sides of the skeleton to account for asymmetry conditions. Ultrasound data collected from live hens at 66 wk of age correlated well with postmortem QUS data (R2 = 0.80, P < 0.0001). Quantitative ultrasonography did not correlate with humeral bone-breaking force measured postmortem. Bones from live hens, surrounded by tissue thicker than 4 mm, could not be read by the QUS probe.

Use of axial X-ray microcomputed tomography to assess three-dimensional trabecular microarchitecture and bone mineral density in single comb white leghorn hens.

Axial x-ray microcomputed tomography is a cost-effective technique with the potential to assess bone mineral density (mg/cc) in both cortical and cancellous bone in Single Comb White Leghorn hens. The technique requires little sample preparation and involves relatively simple data processing. The system described in this research is based on compact fan-beam type tomography, using a tungsten-anode x-ray tube with a relatively small focal spot (approximately 5 microm), coupled with a high-resolution x-ray detector system (approximately 10 microm). To produce a real 3-D data set using microcomputed tomography, x-ray projection views were acquired at 720 equally spaced angular positions (0.5 degrees) around the object of interest. These groups of views were then used to reconstruct a computed tomography image. A test grid with orthogonal test lines was used to calculate bone volume and bone surface. From these calculations, parallel plate equations were used to derive trabecular architectural parameters such as average trabecular plate thickness and average trabecular plate separation. Three-dimensional microarchitecture was evaluated using specialized stereological analysis software. Significant relationships between apparent bone mineral density (mg/cc) and 3-D structure were observed in femoral specimens from 66-wk-old Single Comb White Leghorn hens.

In situ synthesis of oligonucleotide arrays by using surface tension.

This work describes the in situ synthesis of oligonucleotide arrays on glass surfaces. These arrays are composed of features defined and separated by differential surface tension (surface tension arrays). Specifically, photolithographic methods were used to create a series of spatially addressable, circular features containing an amino-terminated organosilane coupled to the glass through a siloxane linkage. Each feature is bounded by a perfluorosilanated surface. The differences in surface energies between the features and surrounding zones allow for chemical reactions to be readily localized within a defined site. The aminosilanation process was analyzed using contact angle, X-ray photoelectron spectroscopy (XPS), and time-of-flight/secondary ion mass spectroscopy (TOF-SIMS). The efficiency of phosphoramidite-based oligonucleotide synthesis on these surface tension arrays was measured by two methods. One method, termed step-yields-by-hybridization, indicates an average synthesis efficiency for all four (A,G,C,T) bases of 99.9 +/- 1.1%. Step yields measured for the individual amidite bases showed efficiencies of 98.8% (dT), 98.0% (dA), 97.0% (dC), and 97.6% (dG). The second method for determining the amidite coupling efficiencies was by capillary electrophoresis (CE) analysis. Homopolymers of dT (40- and 60mer), dA (40mer), and dC (40mer) were synthesized on an NH(4)OH labile linkage. After cleavage, the products were analyzed by CE. Synthesis efficiencies were calculated by comparison of the full-length product peak with the failure peaks. The calculated coupling efficiencies were 98.8% (dT), 96.8% (dA), and 96.7% (dC).