Biomedical subjects
Publications and source records attributed to E Amtmann.
By analogy with the statistical product-moment-correlation coefficient, an area-moment-correlation coefficient is defined for arbitrarily limited sectional areas. 2 numerical methods to determine the coefficient are deduced and exemplified using simple mathematical figures. The methods described are suitable for quantifying the shape of plane figures and for making the shape amenable to statistical analysis.
Alterations in cross-sectional shape at midlength of the femur, tibia, and humerus of 16 male Beagle dogs exposed for 6 months to either 2.1 g or 2.6 g by centrifugation were analysed by the area moment correlation coefficient, as defined by AMTMANN and POTULSKI (1981). As shown by variance analysis the cross-sectional shape differences between bones are highly significant, while the treatment effects are only significant at a 5% level. While the femur and the tibia are almost alike in the shape of their whole sectional area and cortical surface, they differ in the shape of their marrow cavity. The most oval cross sections were found in the humerus. In femur and humerus the shape of the whole sectional area, the marrow cavity and the cortical surface tend to be more oval in the centrifuged animals than in the controls. In the tibial cross sections the opposite is the case. A significant interaction "Gravity X Bone" was found for the shape of the marrow cavity.
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Bovine papilloma virus (BPV) appears to be the etiological agent of common equine connective tissue tumors. We investigated the physical state of the viral DNA within such tumors and found no indication for integration into the host genome. The BPV genomes were present as free circular episomes. Two equine sarcoids were shown to contain multiple copies of free circular BPV type 1 (BPV-1) DNA. When the tumors were digested with several single-cut restriction enzymes, there were only form III BPV-1 DNA sequences could be revealed. One of the sarcoids contained, apart from wild-type BPV-1 DNA, a class of smaller BPV-1 circular DNA molecules bearing a deletion of approximately 9% of the BPV-1 genome. This deletion is located in the physical map between the relative units 0 and 0.32.
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Members of the SV40-polyoma subgroup of papovaviruses share homologous sequences which have been conserved during evolution. The genome of HD virus displays homologies both to the origin of SV40 DNA replication and to the region coding for the VPI capsid protein. As in the case of SV40, both regions are discontinuously arranged in the HD genome.
Blunt traumata cause injury to the thorax and intrathoracic organs by deforming the chest wall and the enclosed structures. Neither examination of the dead person and re-enactment of the accident nor experimental studies on the living or dead person can fully elucidate the course of events. A more satisfactory approach is to use biomechanic models to simulate the structure of the thorax and the type of deformation it undergoes when subjected to various traumata. Such an elasto-static analysis presupposes knowledge of (1) the global geometry of the thorax; (2) the cross sectional geometry of the individual components; (3) the mechanical properties of the material; (4) the force of the impact; (5) concomitant conditions. The results obtained with the models are reviewed. They make it possible to predict the deformation of the thorax in response to the force of the impact, the location and type of fracture of the ribs and the deformation of the intrathoracic organs.
Sixteen male Beagle dogs, 293 to 509 days old, were exposed almost continuously for 3 months to 2.0 G on a 7.9m radius centrifuge. The dogs were maintained on the centrifuge by means of a specially designed, automated waste disposal and life support system. Bone density was measured by a 125I Profile Scanner in the anterior, medial posterior and lateral cortex of the femoral mid-shaft. As compared to mean density in the femora of normal gravity controls, centrifuged dogs showed a 0.8% (P less than 0.05) lower mean linear absorption in their femora. However, the regression of density on the square-root of cross-sectional area/pi differs very significantly in the animals living at earth gravity and those living at hypergravity. Thin hypergravic bones are denser, thick hypergravic ones are less dense than the corresponding ones of normal gravity controls.
Alterations in density of the femur of female Sprague-Dawley rats exposed to chronic centrifugation of 2.76 G for 810 days were studied. The density was measured by photon absorptiometry, using a 125I Profile Scanner. The photon absorption measurements were taken: (1) on bone sections from the midshaft of the femur in the anterior, posterior, medial and lateral cortex with the beam path parallel to the shaft axis, and (2) on the femur near the midshaft with the beam path perpendicular to the shaft axis. The latter were correlated with the cross-sectional area in the midshaft. Compared with femora of age-matched rats (age controls) and of rats having body masses comparable to the centrifuged group (weight controls), kept under earth gravity, the chronically centrifuged animals showed no average no significant differences in photon absorption (density) in the four positons in midshaft. The absorption measurements perpendicular to the shaft axis in all groups differ significant differences between the centrifuged group and the control groups. When cross-sections of equal size are compared, the density of the rat femora is clearly higher in the centrifuged animals than in the control groups. In contrast, the age and weight controls do not differ significantly in density. The results suggest that the increased stress in the rat femora due to centrifugation is reflected in an increased bone density.
25 female Sprague-Dawley rats were placed on a 3.66 m radius centrifuge and subsequently exposed almost continuously for 810 days to 2.76 G. Compared to normal gravity controls, the most noticeable effect of hypergravity was the inhibition of growth of the centrifuged animals. The rats exposed to hypergravity showed on average a smaller femur length (-6.5%), a smaller cross-sectional area (-7.7%, when expressed linearly, i. e. (area/pi)1/2), and smaller outer and inner cross-sectional radii (linearly -9.3% and -12.3%) at the mid-shaft of the femoral bones. The growth inhibition of 3 hind-leg muscles was on average significantly less ranging from (-3.5% to -4.1%), compared to the growth inhibition of the linear dimension of the femur. Statistically there was no difference in the slope and elevation of the regression of the square-root of the cross-sectional area divided by pi on the length of the femur between centrifuged animals and their 16 age matched controls. In the weight control group of 24 animals, comprised of 34,74, and 102 day old rats, the corresponding regression line was parallel and lower in elevation by -12.8%, compared to the line for the centrifuged and age control groups. But, compared to the regression derived from all control animals ranging from 34 to 840 days of age, the cross-sectional area at the mid-shaft of the femur was 8.4% greater in the rats exposed to 2.76 G for 810 days. The slopes of the regression of the outer radius at mid-shaft on the length of the femur were the same in the centrifuged group and in the weight and age control groups of animals. But, the regression lines differed in elevation by -4.4% on average between the centrifuged and age control animals. The line for the regression of the inner radius at the mid-shaft on the length of the femur was parallel and lower in elevation by -7.6% in the centrifuged animals compared to the line for the age controls. But, compared to all control animals living at normal gravity, the outer radius was increased by 3.0% and the inner radius was decreased by 5.7% in the animals exposed to 2.76 G for 810 days. Since the centrifuged animals were all 840 days old, while the controls were from 34 to 840 days old, only further experiments comparing centrifuged and control animals of the same age at various growth stages will be able to furnish evidence for an unambiguous bone hypertrophy. The regressions of the cube-root of body weight on length of the femur deviate significantly in the 3 groups of animals. The heavier rats of the age control group have relatively shorter femurs than the lighter animals. The opposite applies to the centrifuged and the weight control groups of rats. Although the rats on the centrifuge are markedly smaller in overall body size than the controls, they exhibit on average the same absolute muscle weights as the animals at earth gravity, if rats of the same overall body size are compared...
Sixteen male Beagle dogs, 293 to 509 days old, were exposed almost continuously for 3 months to 2.0 G on a 7.9 meter radius centrifuge. The dogs were maintained on the centrifuge, by means of a specially designed automated waste disposal and life support system. As compared to the mean values of normal gravity controls, centrifuged dogs showed no differences in femur length; cross-sectional area, outer and inner radii at mid-shaft of the femur; dry weights of the biceps femoris, quadriceps femoris, and gastrocnemius muscles. It was shown by analysis of covariance that chronic centrifugation has no effect on the relationship between the length and the cross-sectional dimensions at mid-shaft of the femur. Photon absorptiometry, however, revealed significant mineral content increases averaging 1.5% at 3 sites, i.e., at the 1/4, 1/2 and 3/4 length of the femur.
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