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Biomedical subjects

P O'Higgins

Publications and source records attributed to P O'Higgins.

17 recordsLinked to original sources
PubMed1992

An automated method for the analysis of trabecular bone structure.

Trabecular structure as well as bone mass is important in studies of bone disease and fracture. An automated method for the direct analysis of two-dimensional trabecular micro-anatomy and its application to human iliac crest bone biopsies is described. Compared with established methods which require expensive equipment and complex software, costs have been reduced and availability increased by using an image analyzer driven by a microcomputer. Routine histological sections are accepted and an editing function enables the removal of artifacts. An elastic window allows field expansion for large specimens. The program enables the rapid assessment of the bone volume and trabecular surface from the intact image, followed by image skeletonization and the deduction of the trabecular length, number, character, and spacing together with the number of trabecular junctions and discontinuities; the trabecular width is calculated indirectly. Images may be stored to disk or printed as permanent records for diagnostic or research purposes.

Biopsy↗
PubMed1992

Skeletal variations of the seventh cervical vertebrae in the mouse with special reference to the foramina transversaria and the accessory foramina.

The formation of foramina transversaria in the seventh cervical vertebra of CBA and C57BL mice and their offspring is found to behave as if it is determined by a single semi-dominant gene. The accessory foramina of Weber (1950) are investigated in the same material. These foramina are classified into two types and their heredity is evaluated.

Animals↗
PubMed1992

The inheritance of vertebral shape in the mouse. I. A study using Fourier analysis to examine patterns of inheritance in the morphology of cervical and upper thoracic vertebrae.

The shapes of cervical and upper thoracic vertebrae from large samples of 2 inbred strains of mice and their F1 offspring were examined using Fourier analysis to investigate in detail the distributions and magnitudes of differences in vertebral shape between different strains of mice, the relationships between parents and offspring and any differences in the inheritance of vertebral shape between successive vertebral levels. Consistent with the findings of an earlier study there was evidence for considerable differences between vertebral levels in the degree to which offspring resemble one or other parent. The results demonstrate that the inheritance of vertebral morphology conforms to a model in which F1s between inbred strains form a triangular relationship with their parents. Furthermore, this relationship varies between vertebral levels. The significance of these findings is considered in relation to the understanding of the mechanisms of character inheritance and evolution and some new directions for research into vertebral column morphogenesis are proposed.

Animals↗
PubMed1991

A study of facial growth in the sooty mangabey Cercocebus atys.

This study examines the pattern of facial bone growth remodelling in the sooty mangabey (Cercocebus atys) by scanning electron microscopy (SEM) of high-accuracy replicas. The efficacy of the technique is appraised by SEM interpretations of facial remodelling in the crab-eating macaque (Macaca fascicularis) and correlative histological examination. The results indicate that the distribution of depository and resorptive areas in Cercocebus closely parallels that which has been observed in Macaca. It is suggested that the different adult facial morphologies in the sooty mangabey and crab-eating macaque are the result of changes in the rates of remodelling events that may be coupled with different patterns of sutural growth (which could not be studied by SEM).

Animals↗
PubMed1991

The effects of disorders of cartilage formation and bone resorption on bone shape: a study with chondrodystrophic and osteopetrotic mouse mutants.

The shapes of scapulae and basi-occipital bones from three genetically distinct achondroplastic mutants and one osteopetrotic mutant in the mouse (achondroplasia, brachymorphic, stumpy and grey lethal), and appropriate controls, have been compared using Fourier analysis and multivariate statistical techniques. Normal littermates were generally similar in shape, but mutants were significantly different from these controls and from each other. The pattern of morphological differences between the mutants and between the mutants and normal controls is examined. These differences are discussed in relation to the different effects of the four genes on bone morphogenesis, and the significance of these findings in relation to the contributions of cartilage formation and bone resorption to skeletal morphogenesis is considered.

Animals↗
PubMed1990

The variability of patterns of sexual dimorphism in the hominoid skull.

Univariate and multivariate statistical analyses are applied to a number of cranial dimensions and angles from living hominoids in order to investigate the patterns of sexual dimorphism in these groups. Clear differences in patterns of cranial sexual dimorphisms are demonstrated not only between genera but also within a single species (Homo). These differences overlay the common finding of a sexual size difference in all groups. The results imply that caution is required in using the sexual dimorphisms of living hominoids as models for those anticipated in fossils.

Animals↗
PubMed1990

Bone surface structure in osteopetrotic grey lethal (gl/gl) and microphthalmic (mi/mi) mutant mice as revealed by scanning electron microscopy.

The surface structure of bone from two genetically distinct osteopetrotic strains of mice, grey lethal (gl) and microphthalmic (mi) has been examined by scanning electron microscopy. Although both conditions produce a classical osteopetrotic phenotype the means by which this is achieved is quite different. gl mice appear to retain woven bone and show no evidence of resorption: mi mice show evidence of imperfect remodelling. These results are in accordance with what is already known of osteoclast structure and function in these mutations.

Animals↗
PubMed1990

The effect of diet on bone shape in the mouse.

The effects of four deficient diets (oats, barley, wheat, buckwheat) on the shape of first and second cervical vertebrae and scapulae in C57BL mice have been measured using Fourier analysis. Bone shape was found to be robust, and only minimally affected by dietary change. The significance of this lack of change is discussed in the light of changes induced by diet in non-metrical variants in the skeleton. The study further emphasises the dangers of using certain non-metrical characters in taxonomic studies and indicates that the shapes of mouse bones are affected to a lesser degree by dietary influences than are the incidences of certain non-metrical character states.

Animals↗
PubMed1989

Developments in cranial morphometrics.

This paper sets out to describe a number of traditional and novel approaches to craniometry. These include linear and angular measurements, indices, shape factors, least squares, and Fourier analysis. A study is presented in which these different techniques are applied to a phenetic analysis of the crania of a variety of living and extinct hominoids, with the aim of assessing the relative merits of different approaches. The results allow an appraisal of the stability of phenetic groupings in the face of different data and suggest that the choice of data can considerably influence the observed pattern of between-group relationships. The choice of craniometric method should be made with due regard for the questions at hand and the interpretation of phenetic relationships should allow for the particular data.

Animals↗
PubMed1989

The effect of the gene undulated (un) on the shape of cervical and upper thoracic vertebrae in the house mouse (Mus musculus).

Videodigitised outlines of C6, C7, T1 and T2 vertebrae from 23 mice carrying the mutant gene undulated (un/un) and normal littermates (+/un) have been examined by Fourier analysis. There were large differences in shape between C6 vertebrae, smaller but significant differences in C7 and insignificant differences between T1s. The situation in T2 was complicated by the effects of the genetic background, but the effect of undulated was still significant. We conclude that the undulated gene shows significant pleiotropy in its effects even over this short length of the vertebral column.

Animals↗
PubMed1989

The relationship between age, size and shape of mouse thoracic vertebrae: a scanning electron microscopic study.

Scanning electron microscopic studies of replicas of the first and second thoracic vertebrae of mice aged 25-60 days allow us to differentiate areas of bone deposition and resorption, the sites of areas of calcified cartilage and the attachments of ligaments. The main site of resorption throughout the period is beneath the neural arch, with other local areas of resorption occurring around the developing vertebral processes. The spinous process increases in size over the period, especially in T2. Results obtained in this way correlate well with an earlier morphometric study of the same bones.

Aging↗
PubMed1988

The relationship between age, size and shape in the upper thoracic vertebrae of the mouse.

The shapes of the first two thoracic vertebrae of F1 mice produced by crossing BALB/c and CBA inbred strains have been examined at 25-60 days by Fourier analysis. The greatest shape change during this period is between 25 and 30 days and is related to the finalisation of the form of the neural arch and spinous process. Between 30 and 60 days there is continued linear shape change not associated with further increase in vertebral area, and probably due to a constant pattern of localised shape changes. Both vertebrae and both sexes behave similarly.

Aging↗
PubMed1986

The clonal model of vertebral column development: a reinvestigation of vertebral shape using Fourier analysis.

Little work has been done on the skeletal system of allophenic mice (chimaeras). In this paper we re-examine the evidence presented for the clonal theory of vertebral development using quantitative methods which take account of variation. We conclude that the clonal theory is either an overly simplistic approximation of the real situation, or that the evidence so far given in its support is unsubstantiated.

Animals↗
PubMed1985

Measurement of biological shape: a general method applied to mouse vertebrae.

A method is described for recording and analysing the projected shape of mouse vertebrae. The image of the shape is captured by a television camera, cleaned, digitized and subjected to mathematical analysis. A visual representation is obtained by reconstructing the shape in polar coordinates about its centre of area. Further statistical analysis of the whole shape is performed after a Fourier transform. This allows the shape to be represented by and reconstructed from 15 numbers. The method does not rely on homologous points or expert opinion and allows mean shapes to be constructed. It successfully distinguished between 92% of the test data, T1 and T2 vertebrae from two strains of mice.

Animals↗
PubMedDate not supplied

Determination of race and sex of the human skull by discriminant function analysis of linear and angular dimensions.

The race and sex of the human skull can be determined by craniometry. In this paper we suggest that a large number of craniometric measurements does not necessarily give the best possible discrimination for race and test the performance of subsets of variables drawn from various skull regions, or extracted mathematically on the basis of their discriminatory power. We also suggest that the best discriminators for race are not necessarily the best for sex, and that skulls of unknown provenance are best tested first for race and then for sex, using different variables for each purpose.

Adult↗