Biomedical subjects

Allan S Jones

Publications and source records attributed to Allan S Jones.

7 recordsLinked to original sources

PubMed2006

Application of invariant grey scale features for analysis of porous minerals.

Three-dimensional (3D) texture analysis can be used to differentiate similar materials which have a complex structural nature that is not easily reduced to geometric primitives. A method which extends the concept of invariant grey scale features to non-structured 3D textures is introduced and applied to the study of five processed mineral carbon materials which are characteristically similar but derive from different industrial sources. X-ray microtomography (XRMT) was used to obtain 3D tomographic data with isotropic voxel spacing of 9.8 microm. These data were used to construct invariant features for 3D texture measurement via Monte Carlo based sampling routines and integrals of grey scale relational kernel functions. The procedure produced multi-component texture vectors, which were successfully tested against texture samples as a classification-recognition tool. Identification accuracies ranging from 69% to approximately 84% were achieved for the five material sources examined. This result provides a sound basis for quantitative analysis of these materials which to date have proved very difficult to examine using traditional image analysis tools because of their complex natural structure.

Journal Article↗

PubMed2006

Physical properties of root cementum: part 8. Volumetric analysis of root resorption craters after application of controlled intrusive light and heavy orthodontic forces: a microcomputed tomography scan study.

INTRODUCTION: Intrusion is a critical type of orthodontic tooth movement in relation to external root resorption. Our aims in this prospective randomized clinical trial were to quantify, 3 dimensionally, the amount of root resorption when controlled light and heavy intrusive forces were applied to human premolars and to establish the sites where root resorption is more prevalent. METHODS: Fifty-four maxillary first premolars, orthodontically indicated for extraction from 27 patients (left and right maxillary first premolars from each), were intruded for 28 days with buccal and palatal beta-titanium-molybdenum alloy 0.017 x 0.025-in cantilever springs. The patients were randomly divided into 3 groups, and various levels of force were used: group 1, heavy force (225 g) on 1 side and control force (0 g) on the contralateral side; group 2, light force (25 g) on 1 side and control force (0 g) on the contralateral side; group 3, light force (25 g) on 1 side and heavy force (225 g) on the contralateral side. After the experimental period, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed by using a microcomputed tomography scan x-ray system (SkyScan-1072, Skyscan, Aartselaar, Belgium) and specially designed software for direct volumetric measurements. RESULTS: The volume of the root resorption craters after intrusion was found to be directly proportional to the magnitude of the intrusive force applied. The results showed that the control group had fewer and smaller root resorption craters, the light force group had more and larger root resorption craters than the control group, and the heavy force group had the most and the largest root resorption craters of all groups. A trend of linear increase in the volume of the root resorption craters was observed from control to light to heavy groups, and these differences were statistically significant. The mean volumes of the resorption craters in the light and heavy force groups were 2 and 4 times greater than in the control groups, respectively. The mesial and distal surfaces had the greatest resorption volume, with no statistically significant difference between the 2 surfaces.

Adolescent↗

PubMed2005

X-ray microtomography of 410 million-year-old optic capsules from placoderm fishes.

The structure of two small ossified optic capsules from mid-Palaeozoic placoderm fishes has been revealed in fine detail, by the use of X-ray microtomography analysis and 3D visualisation software. These two specimens are 410 million-year-old; they were collected from an Early Devonian (Lochkovian) limestone in central New South Wales, and are the oldest known optic capsules from jawed fishes. The capsules show attachment areas for seven extrinsic eye muscles, rather than the six until recently deemed universal for gnathostomes. The analysis also revealed structures within the ossified cartilage which covered the medial surface of the eyeball, including nerve tracts, vascular canals, and possibly a choroid rete mirabile.

Animals↗

PubMed2004

Direct neural network application for automated cell recognition.

BACKGROUND: Automated cell recognition from histologic images is a very complex task. Traditionally, the image is segmented by some methods chosen to suit the image type, the objects are measured, and then a classifier is used to determine cell type from the object's measurements. Different classifiers have been used with reasonable success, including neural networks working with data from morphometric analysis. METHODS: Image data of cells were input directly into neural networks to determine the feasibility of direct classification by using pixel intensity information. Several types of neural network and their ability to work with cells in a complex patterned background were assessed for a variety of images and cell types and for the accuracy of classification. RESULTS: Inflammatory cells from animal biomaterial implants in rabbit paravertebral muscle were imaged in histologic sections. Simple, three-layer, fully connected, back-propagation neural networks and four-layer networks with two layers of a shared-weights neural network were most successful at classifying the cells from the images, with 97% and 98% correct recognition rates, respectively. CONCLUSIONS: The high accuracy recognition rate shows the potential for direct classification of visual image pixel data by neural networks.

Animals↗

PubMed2004

A calibration method used for volumetric measurement of orthodontically induced root resorption craters.

The aim of this study was to measure the accuracy and reproducibility of volumetric estimations obtained by a commercial software used to measure resorption craters induced by orthodontic forces. Twenty human first maxillary premolars were selected and divided into light and heavy force groups with 25 and 225 g of force applied to the upper-right first premolars, respectively. The contralateral teeth served as controls. Samples were extracted and prepared for SEM stereoimaging after 28 days of force application. Volumetric measurements of these resorption craters were generated by the software. Standardized pyramidal indentations by the Vickers microhardness tester on four solid metallic cylindrical rods (brass, copper, stainless steel, and aluminum) similar to the dimensions of human premolars were used for calibration. Mathematically calculated volumes of these indentations were compared to volumes estimated by the software. The software estimated the errors of volumes of pyramidal indentations of the harder and softer materials to within 11 and 19%, respectively. Non-uniform plastic deformation that occurred in softer materials during indentation distorts the calculated results. The estimates obtained by the software even for distorted indentations caused by non-uniform plastic deformation have high degrees of reproducibility and accuracy.

Bicuspid↗

PubMed2004

A new method for volumetric measurement of orthodontically induced root resorption craters.

This method was designed to quantify root resorption on human premolar root surfaces induced by orthodontic forces by volume. Light (25 g) or heavy (225 g) orthodontic forces were applied to 20 first maxillary premolars in 10 human subjects. The contralateral teeth of the subjects served as controls. All teeth were extracted after 28 d of experimentation and prepared for imaging. A pair of stereo scanning electron microscopy (SEM) images (+/-3 degrees ) of resorption craters was captured and imported into an image analysis software package. The images were aligned and grayscale depth maps of the craters were generated. Correction for errors due to residual tilt and curvature of the cementum surface using shading correction was performed. Thresholding was used to obtain a measure of both the cementum surface height and the average depth of the crater. The depth of the crater was the difference in these values. Crater volumes were obtained by multiplication of the average of this difference by area of the crater. Calibration of this volumetric measurement against standardized calculated known volumes on metallic rods showed good accuracy and reproducibility. In the experimental teeth, heavy forces caused threefold more resorption than light forces (P < 0.01). There was also more root resorption evident in the experimental teeth compared with the control teeth in both the light and heavy force groups.

Bicuspid↗

PubMed2003

Visualizing lipid structure and raft domains in living cells with two-photon microscopy.

The lateral organization of cellular membranes is formed by the clustering of specific lipids, such as cholesterol and sphingolipids, into highly condensed domains (termed lipid rafts). Hence such domains are distinct from the remaining membrane by their lipid structure (liquid-ordered vs. -disordered domains). Here, we directly visualize membrane lipid structure of living cells by using two-photon microscopy. In macrophages, liquid-ordered domains are particularly enriched on membrane protrusions (filopodia), adhesion points and cell-cell contacts and cover 10-15% of the cell surface at 37 degrees C. By deconvoluting the images, we demonstrate the existence of phase separation in vivo. We compare the properties of microscopically visible domains (<1 microm2), with those of isolated detergent-resistant membranes and provide evidence that membrane coverage by lipid rafts and their fluidity are principally governed by cholesterol content, thereby providing strong support for the lipid raft hypothesis.

Animals↗