VOLUMETRIC IMAGE PROCESSING FOR THREE-DIMENSIONAL DISPLAY OF THE SKELETAL ANATOMY OF THE SEA OTTER

Volumetrically correct, three-dimensional color images of the sea otter, ( Enhydra lutris ), were generated from computed tomographic (CT) data using a Sun 3/160 workstation and a Pixar Imaging Computer. These images could be displayed as static images (1024×768) or rotated about any axis in real-time by displaying sequential rotation sequences generated by the Pixar Imaging Computer. The images provided realistic depth of field through overshadowing and differential opacification. This was obtained through an opacification algorithm which traced rays from a selected viewing plane through colored gel volumes, and calculated absorbance percentages as a function of the transparency of the gels penetrated. Reconstructions of this type serve as alternative anatomy tutorials for species otherwise unavailable for routine dissection. They also permit topographical studies without interfering with populations of endangered animals.     

The Seismic Structure of the Sun

Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics.     

Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

Monovalent salt-induced gelation of enzymatically deesterified pectin

Pectin gels were induced by monovalent salts (0.2 M) concurrently with deesterification of high methoxy pectin using a salt-independent orange pectin methylesterase (PME). Constant pH was maintained during deesterification and gelation. If salt or PME was absent, the pectin did not form a gel. The gel strength was influenced by both pH and species of monovalent cation. At pH 5.0, the pectin gel induced by KCl was significantly stronger than the NaCl-induced gel. In contrast, a much stronger gel was produced in the presence of NaCl as compared to KCl at pH 7.0. LiCl did not induce pectin gelation at either pH. Molecular weights of pectins increased from 1.38 x 10(5) to 2.26 x 10(5) during NaCl-induced gelation at pH 7. One proposal to explain these pectin molecular weight changes is a hypothetical PME transacylation mechanism. However, these pectin molecular weight changes can also be explained by metastable aggregation of the enzymatically deesterified low methoxy pectin. We postulate that gelation was induced by a slow deesterification of pectin under conditions that would normally salt out (precipitate) low methoxy pectin in the absence of PME.     

The Current State of Solar Modeling

Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.     

Molecular mechanism of Chinese medicine formula (Bushen Bugu Tang) for the treatment of postmenopausal osteoporosis

AIM: To study the molecular mechanism of Chinese medicine formula Bushen Bugu Tang (BSBGT) for the treatment of postmenopausal osteoporosis (PMO). METHODS: Forty female SD rats were divided into four groups: the sham group, OVX group, estrogen treatment group and BSBGT treatment group, ten for each, difference operation and treatment were given. Subsequently, bone mineral density (BMD), bone histomorphometric changes and collagen type I expression in the femur of these rats were examined. In order to position the target of the formula acting on bone, the effect of BSBGT on regulation of mRNA levels of RANKL and OPG, two key factors for regulating osteoclastogenesis, by using rat calvarial-derived stromal cell cultrues, was elucidated. RESULTS: The BSBGT formula was found as effective as estrogen in preventing the reduction of BMD, the trabecular area and trabecular numbers in femora and also the decrease in collagen type I expression following ovariectomy. RT-PCR resulted showed that both estrogen and BSBGT significantly up-regulated OPG mRNA level and down-regulated RANKL mRNA level, resulting in an increased ratio of OPG/RANKL in cultured rat stromal cells. CONCLUSIONS: The ratio of OPG/RANKL within the osseous environment determines whether bone formation predominates bone resorption. We therefore concluded that the BSBGT formula might be as effective as estrogen in prevention of postmenopausal osteoporosis through the mechanism of up-regulating RANKL expression and down-regulating OPG expression in osteoblast/stromal cells.     

Down-regulation of MHC class II receptors of DH82 cells, following infection with Ehrlichia canis

In order to evaluate whether infection with E. canis alters the expression of major histocompatibility complex (MHC) class I and/or MHC class II receptors, and by doing so alters the immune response to the organism, flow cytometry was performed on DH82 cells infected with Ehrlichia canis (90% infection) and on uninfected DH82 cells of the same passage, using anti-canine MHC class I and II antibodies. MHC class II expression was evident in 47.6 and 46.2% (mean 46.9%) of uninfected DH82 cells using two different anti-MHC class II antibodies, while no MHC class II expression was evident in DH82 cells infected with E. canis. The present results indicate that infection of DH82 macrophages with E. canis down-regulates their MHC class II receptors. These results suggest a possible mechanism by which E. canis evades the immune system.