Bone measurement by enhanced contrast image analysis: ovariectomized and intact Macaca fascicularis as a model for human postmenopausal osteoporosis.

This paper presents an image enhancement and analysis system (DARWIN) based on an inexpensive microcomputer and applies the system to two bone morphometry problems relevant to postmenopausal osteoporosis. Using ovariectomized and intact female Macaca fascicularis as a model, we examined the radiodensity of the sixth lumbar vertebra and the cross-section area of the right femur. Significantly lower bone density was observed in the vertebral segments of the ovariectomized animals. No significant differences were observed in comparisons of the femoral cross sections. The reduction in radiographic density of the ovariectomized animals' vertebrae is similar to that observed in postmenopausal women, supporting the use of female cynomolgus macaques as models of bone loss in postmenopausal osteoporosis.

Computer-assisted image analysis of plant growth, thigmomorphogenesis and gravitropism.

A nonintrusive auxonometric system, based on the DARWIN image processor (Telewski et al. 1983 Plant Physiol 72: 177-181), is described and demonstrated in the analysis of gravitropism and thigmomorphogenesis in corn seedlings (Zea mays). Using this system, growth and bending of regularly shaped plants or organs can be quickly and accurately measured without, in any way, interfering with the plant. Furthermore, the growth and bending curves are automatically plotted. Thigmomorphogenesis in the aerial part of corn seedlings involves growth promotion at a low force load and growth retardation at higher force loads. The time courses of the two kinds of response are somewhat different, with retardation occurring immediately after mechanical perturbation and growth promotion taking somewhat longer to begin. Gravitropic experiments show that when dark-grown corn seedlings are placed on their side in the light, the resulting curvature is due to two consecutive morphological mechanisms. In the first instance, lasting for about 15 minutes, the elongation of the bottom edge of the plant accelerates, while the elongation of the top edge remains constant. After that, for the next 1.75 hours, the elongation of the top edge decelerates and stops while that of the bottom edge remains constant at the increased rate for most of the period. The measurements taken from both experiments at relatively high resolution (0.08-0.1 millimeter) show that the growth curves are not smooth but show many small irregularities which may or may not involve micronutations.

Computer-Assisted Image Analysis of Tissues of Ethrel-Treated Pinus taeda Seedlings.

A microcomputer based video image analyzer is described and demonstrated in the analysis and comparison of tissue types of 6-month-old Ethrel-treated and control seedlings of loblolly pine (Pinus taeda L.). Two different programs were employed. ;Topographer I' sought, identified, and measured cell or resin canal lumen areas, and ;Area' measured tracheid length and silhouette areas. Ethrel treatment induced an increase in radial growth and a decrease in shoot elongation and needle growth. Bark production was stimulated by the same treatment. The tracheid lumens of Ethrel-treated plants were shorter and had a smaller cross-sectional area, whereas the tracheid cell walls increased in thickness. The treatment also increased resin canal formation in the xylem.