Skeleton Pattern Research Articles

Specific and redundant functions of the paralogous Hoxa-9 and Hoxd-9 genes in forelimb and axial skeleton patterning

Using gene targeting, we have produced mice with a disruption of Hoxa-9 or Hoxd-9, two paralogous Abdominal B-related genes. During embryogenesis, these genes are expressed in limb buds and along the vertebral axis with anterior expression boundaries at the level of prevertebra #20 for Hoxa-9 and #23 for Hoxd-9. Skeletal analysis revealed homeotic transformations corresponding to anteriorisations of vertebrae #21 to #25 (L1 to L5) in the lumbar region of Hoxa-9-/- mutants; vertebrae #23 to #25 (L3 to L5) in the lumbar region together with vertebrae #28, #30 and #31 (S2, S4 and Ca1) in the sacrum and tail were anteriorized in Hoxd-9-/- mutants. Thus, anteriorisation of vertebrae #23 to #25 were common to both phenotypes. Subtle forelimb (but not hindlimb) defects, corresponding to a reduction of the humerus length and malformation of its deltoid crest, were also observed in Hoxd-9-/-, but not in Hoxa-9-/-, mutant mice. By intercrosses between these two lines of mutant mice, we have produced Hoxa-9/Hoxd-9 double mutants which exhibit synergistic limb and axial malformations consisting of: (i) an increase of penetrance and expressivity of abnormalities present in the single mutants, and (ii) novel limb alterations at the level of the forelimb stylopod and additional axial skeleton transformations. These observations demonstrate that the two paralogous genes Hoxa-9 and Hoxd-9 have both specific and redundant functions in lumbosacral axial skeleton patterning and in limb morphogenesis at the stylopodal level. Taken all together, the present and previously reported results show that disruption of different Hox genes can produce similar vertebral transformations, thus supporting a combinatorial code model for specification of vertebral identity by Hox genes.

MORPHOLOGICAL EVOLUTION OF THE SCAPULA IN TREE SQUIRRELS, CHIPMUNKS, AND GROUND SQUIRRELS (SCIURIDAE): AN ANALYSIS USING THIN-PLATE SPLINES.

The mammalian scapula, like many bones, is a single structural element that serves as an attachment site for several muscles. The goal of this study was to determine whether the scapula evolves as an integrated unit, or as a collection of distinct parts. Shape differences among the scapulae of tree squirrels, chipmunks, and ground squirrels were described using thin-plate spline analysis. This technique produces a geometric description of shape differences that can be decomposed into a series of components ranging in scale from features that span the entire form to features that are highly localized. Shape differences among tree squirrel scapulae were found only in large-scale features, indicating spatially integrated shape change. Chipmunks and ground squirrels differ from tree squirrels in several features, but shared differences reflecting divergence of their common ancestor were found only in the small-scale features. Divergence of ground squirrels from the common ancestor involved some large-scale changes but was dominated by small-scale changes. Divergence of chipmunks was dominated by large-scale changes. Thus, the scapula evolved as an integrated unit during some transitions but as a collection of distinct parts during others. These results suggest that evolutionary patterns of the postcranial skeleton may be as complex as the patterns that have been described for skulls and feeding mechanisms.

A novel fast and reliable thinning algorithm

Abstract In this paper a new algorithm is proposed for skeletonizing binary digital images. The algorithm does not employ the conventional pixel- or non-pixel-based techniques. Instead, it identifies regions of particular shapes in the image and substitutes apppropriate skeleton patterns for them. Initially, as many horizontal and vertical strips as possible are detected. These correspond to rather straight, long and narrow regions in the original image. Any remaining regions correspond to joints between strips. The strips are then grouped into trapezoidal regions which may be replaced by the appropriate skeleton patterns. The individual skeleton patterns are then merged using the skeletons due to the jointing regions, generating the final skeleton. A compact representation is obtained for post-processing, and the issue of robustness with respect to noise is addressed.

Enantiomeric separation of racemic isoflavanones and related compounds on (+)-poly(triphenylmethyl methacrylate)-coated silica gel

(+)-Poly(triphenylmethyl methacrylate)-coated silica gel [Chiralpack OT(+)] was used for the separation of enantiomers of racemic isoflavanone, homoisoflavanone, isoflavan and 2-benzyltetralone derivatives. All the enantiomers of the above-mentioned compounds were separable. The efficiency of the separation depended on both the skeleton and substitution pattern of the racemic compounds. A relation between the number and polarity of substituents in the aromatic rings and the resolution and separation factors was observed.

Competitive overgrowth and post-Paleozoic macroevolution of marine bryozoa

The Lower Ordovician through Upper Jurassic record of the phylum Bryozoa consists almost entirely of the class Stenolaemata, excepting a very few Gymnolaemata (ichnofossils of the order Ctenostomata and, in the uppermost Upper Jurassic, Pyriporopsis, which is the oldest known Cheilostomata). Along with the decline to eventual extinction of most Paleozoic stenolaemates beginning with the end-Permian crisis, the stenolaemate order Cyclostomata radiated in Late Triassic and Jurassic to include the diversity of growth forms and locally the abundance common for Paleozoic bryozoan faunas. By late Cretaceous, however, cheilostomes had diversified and had come to dominate in bryozoan faunas; they have continued to dominate to the present.In the abundant and diverse bryozoan fauna of the northern Adriatic Sea, cheilostomes are four to five times as diverse and are orders of magnitude more abundant than are cyclostomes. Within this fauna, encrusting sheet-like cheilostomes consistently overgrow adjacent encrusting cyclostomes. Different ontogenetic patterns of skeleton and organs, as well as larger zooid sizes at colony margins, produce patterns of feeding currents that allow cheilostomes to deliver their filtered water to and to overtop competing cyclostomes at interacting margins. These Bauplan differences apparently constitute a key evolutionary innovation characterizing the Cheilostomata. Along with higher growth rates in most cheilostomes, this key evolutionary innovation should have given cheilostomes a competitive edge since the origin of multiserial colonies within the clade in Early Cretaceous. It is hypothesized that superior overgrowth capability of cheilostomes has been an important factor in their success and the relative decline of cyclostomes.

Long-term Effects of Rigid Fixation on the Growing Craniomaxillofacial Skeleton

Fixation of craniomaxillofacial bones with plates and screws is becoming an increasingly popular method of managing patients with maxillofacial fractures, congenital anomalies, and skeletal defects after tumor extirpation. The effects of rigid fixation on growth, however, are not well defined and remain controversial. This experimental work was designed to evaluate the effects of rigid fixation on the growing craniomaxillofacial skeleton. Eight 2-month-old beagle dogs were divided into two groups. Cephalometric analysis and computed tomography were obtained preoperatively to establish a baseline of the craniomaxillofacial skeleton. Rigid fixation using plates and screws was applied across the intact coronal and nasofrontal sutures. The contralateral side served as the control. The periosteum was elevated over the contralateral suture and replaced without any surgical intervention. The animals were killed one year after application of rigid fixation, when they had achieved full and mature skeletal growth. The skulls were evaluated both grossly and cephalometrically. There was bony growth over some of the plates, as well as sclerosis of the plated suture lines. Cephalometric analysis demonstrated consistent asymmetry between the plated and nonplated sides, with deviation of the midline toward the plated side in all of the animals. Although further studies are necessary to clarify this issue fully, we conclude from our study that rigid fixation during skeletal development can potentially alter the growth patterns of the craniomaxillofacial skeleton and should be used with caution.

Development and application of vehicle‐license number recognition system using real‐time image processing

AbstractThe authors have proposed a system architecture and a high‐speed method to extract characters (a four‐digit vehicle number) on a vehicle license plate for a realtime vehicle license number recognition system. This paper describes the results of field tests of a system which is based on the previous work but with some further developments. To identify characters on a vehicle license plate, a template‐matching method is used which compares the skeleton pattern of characters and its background pattern. To use the system at night, a continuous illumination with two light sources is employed. The experiments including simulations confirm the usefulness of the proposed method at night. The field tests show that about 75 percent of all passing vehicles were recognized successfully in the daytime and about 55 percent at night. The average processing time is about 150 ms, and the 98 percentile value is about 410 ms. These values are sufficient for practical measurements of a vehicle traveling time (between two points). This paper describes also a system to give traveling information to vehicle users, by employing message boards as an example of application of the proposed system.

Normal Radiologic Patterns and Variances of the Human Skeleton: An X-Ray Atlas of Adults and ChildrenNormal Radiologic Patterns and Variances of the Human Skeleton: An X-Ray Atlas of Adults and Children. By BirknerRudolf, M.D. Cloth, $74.00. Pp. 536, with 1,227 figures including 803 full-size radiographs. Baltimore, Urban and Schwarzenberg, 1978.

HomeRadiologyVol. 132, No. 1 PreviousNext Book ReviewNormal Radiologic Patterns and Variances of the Human Skeleton: An X-Ray Atlas of Adults and ChildrenWillam MartelWillam MartelWillam MartelPublished Online:Jul 1 1979https://doi.org/10.1148/132.1.42MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Article HistoryPublished in print: July 1979 FiguresReferencesRelatedDetailsRecommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 132, No. 1 Metrics Altmetric Score PDF download

Book ReviewNormal Radiologic Patterns and Variances of the Human Skeleton: An x-ray atlas of adults and children

Book ReviewNormal Radiologic Patterns and Variances of the Human Skeleton: An x-ray atlas of adults and children

Covariation patterns in the postcranial skeleton of moas (Aves, Dinornithidae): A factor analytic study

The covariation patterns of the postcranial skeleton in eight species of moas (Aves, Dinornithidae) from the Pleistocene of New Zealand are described using multiple factor analysis. Rotation schemes include an orthogonal Varimax and oblique (direct quartimin) simple structure solutions.Four major patterns of covariation are resolved: a length factor, primarily that of leg length; a width factor, including pelvis width and long bone widths; a sternal breadth factor; and a sternal length-posterior pelvis length factor. The first two patterns represent a functional separation between body size and those aspects of the skeleton, scaling allometrically, adapted to support body weight. The sternal breadth factor may indicate that features contributing to trunk support are independent from those width measurements of the pelvis and hindlimb bones. The sternal length-posterior pelvis length factor reveals a pattern of covariation that is somewhat independent of other patterns (long bone lengths) determining variability in body size.

Information Networks in Generative Computer-Assisted Instruction

An environment is described in which a computer dynamically generates simple instructional and remedial sequences for nonnumeric topics such as geography and biology. This environment is described in detail and consists of a structured pool of information and sets of mechanisms (skeleton patterns) that extract data from the pool. The environment is implemented in the form of an interactive ALGOL program on the Burroughs B5500, and examples of interactions with students are included.