PubMed Health⌕ Search

Biomedical subjects

J T Richtsmeier

Publications and source records attributed to J T Richtsmeier.

18 recordsLinked to original sources
PubMed1992

Oculoauriculovertebral anomaly: segregation analysis.

Seventy-four families of probands with oculoauriculovertebral anomaly were evaluated, including 116 parents and 195 offspring. Relatives were examined to identify ear malformations, mandibular anomalies, and other craniofacial abnormalities. For segregation analysis using POINTER, selection of the sample was consistent with single ascertainment. Different population liabilities were used for probands and relatives, because affection was narrowly defined for probands and broadly defined for relatives. The hypothesis of no genetic transmission was rejected. The evidence favored autosomal dominant inheritance; recessive and polygenic models were not distinguishable.

Adult↗
PubMed1992

On comparing biological shapes: detection of influential landmarks.

For problems of classification and comparison in biological research, the primary focus is on the similarity of forms. A biological form consists of size and shape. Several approaches for comparing biological forms using landmark data are available. If the two biological forms are demonstrated to be different, the next important issue is to localize the differences by identifying those areas which differ most between the two objects. In this paper we suggest a technique to detect influential landmarks, those which contribute most to the difference between forms. We study the effectiveness of the technique using three-dimensional simulated data sets and two examples. Results suggest that the technique is useful in the study of biological form and its variation.

Acrocephalosyndactylia↗
PubMed1992

Cranial growth in the squirrel monkey (Saimiri sciureus): a quantitative analysis using three dimensional coordinate data.

Improvements in data gathering technology have made it possible to quickly and accurately digitize large numbers of objects. The three dimensional coordinates of 44 homologous landmarks were obtained from a sample of 104 squirrel monkey (Saimiri sciureus) crania. After sorting by sex, the crania were assigned to one of four dental age groups. Two quantitative methods, Euclidean distance matrix analysis (EDMA) and finite element scaling analysis (FESA), were used to study craniofacial form change during growth within each sex. Form differences between the sexes at each developmental age were also examined. Both sexes show a small amount of cranial growth overall; however, there are areas of substantial local growth. These areas include the anterior neurocranium and basicranium, the basioccipital, and the anterior palate. Sexual dimorphism in the craniofacial complex is minimal. The most dimorphic regions are the orbitonasal portion of the lower face, the cranial base, and the palate.

Animals↗
PubMed1992

Experiments of nature: premature unicoronal cranial synostosis in mantled howler monkeys (Alouatta palliata).

In 1960 Adolph Schultz described several cases of plagiocephaly in a collection of mantled howler monkeys (Alouatta palliata) from the forests of Central America. Since then several more specimens have been described. These individuals make up one of the largest samples of nonhuman primates that are affected by craniosynostosis. In this study, we used finite element scaling analysis (FESA) to quantify morphologic differences between adult normal (N = 19) and plagiocephalic female howler monkeys (N = 4). FESA utilizes three dimensional coordinate data to provide detailed information on size and shape differences local to biologic landmarks. The relatively large number of plagiocephalic howler monkeys provides a natural means for examining hypotheses concerning patterns of dysmorphology associated with plagiocephaly. Comparison of our results to observations from the clinical literature reveals similarities in neurocranial and facial morphology among plagiocephalic humans and howler monkeys, but the direction and magnitude of local form differences between howler monkeys and humans indicate species-specific responses to sutural constraint. Few cases of craniosynostosis in nonhuman primates are known. The number of plagiocephalic howler monkeys suggests these monkeys may be particularly susceptible to some defect that leads to premature suture closure. If this is the case, then howler monkeys may be a good model to study the cause(s) of craniosynostosis.

Alouatta↗
PubMed1991

Morphometric analysis of craniofacial growth in Cebus apella.

The present study was undertaken to provide a quantitative description of craniofacial growth in Cebus apella in three dimensions. Landmarks from a cross-sectional sample of sexed and dentally aged crania were collected using a 3Space digitizer. Two methods of three-dimensional form analysis, euclidian distance matrix analysis (EDMA) and finite-element scaling analysis (FESA), were used to investigate growth changes in the cranium. Male and female growth was examined by comparing the youngest male mean form to all other age/sex specific mean forms. In addition, form differences between the sexes were studied by comparing male and female mean forms at each age. The cranium was divided into four regions for analysis: muzzle, upper face, neurocranium, and basicranium. Growth changes within each region were examined. In the muzzle and neurocranium, most growth occurs along the anteroposterior axis. Growth around pterion and the lower orbital rim is prominent within the upper face. The basicranium shows a surprisingly large amount of form change with growth. This form change is due to the mediolateral expansion of the basioccipital, and to the posterior migration and inferior rotation of basion. Males and females have similar growth patterns, but males tend to be larger than females in nearly all dimensions at every developmental age except the youngest. Evidence suggests that craniofacial sexual dimorphism is primarily due to males growing faster than females for approximately the same amount of time.

Animals↗
PubMed1991

Euclidean distance matrix analysis: a coordinate-free approach for comparing biological shapes using landmark data.

For problems of classification and comparison in biological research, the primary focus is on the similarity of forms. A biological form can be conveniently defined as consisting of size and shape. Several approaches for comparing biological shapes using landmark data are available. Lele (1991a) critically discusses these approaches and proposes a new method based on the Euclidean distance matrix representation of the form of an object. The purpose of this paper is to extend this new methodology to the comparison of groups of objects. We develop the statistical versions of various concepts introduced by Lele (1991a) and use them for developing statistical procedures for testing the hypothesis of shape difference between biological forms. We illustrate the use of this method by studying morphological differences between normal children and those affected with Crouzon and Apert syndromes and craniofacial sexual dimorphism in Cebus apella.

Acrocephalosyndactylia↗
PubMed1991

The effect of rigid fixation on growth of the neurocranium.

The effects on skull growth of plating the coronal suture and frontal bone were studied in New Zealand White rabbits. Three-dimensional coordinate landmarks were digitized and analyzed to determine the differences in form between operated and unoperated animals using Euclidian distance matrix analysis. This method compares sets of interlandmark distances in three dimensions and was used to demonstrate changes induced by plating. We interpret these changes in morphology to be the result of differences in growth between the operated and unoperated groups. Periosteal elevation alone (n = 6) resulted in a minimal local growth increase. Coronal suture plating (n = 8) resulted in local growth restriction with contralateral and adjacent size increases. Frontal bone plating (n = 6) without crossing a suture line also resulted in local growth restriction and adjacent bone size increases. The timing of intervention in relation to the completion of bone growth may explain the magnitude of clinically apparent effects. Changes in bones adjacent to those directly manipulated may be an attempt to maintain a normal skull volume.

Animals↗
PubMed1991

Similarities in Aegyptopithecus and Afropithecus facial morphology.

Recently discovered cranial fossils from the Oligocene deposits of the Fayum depression in Egypt provide many details of the facial morphology of Aegyptopithecus zeuxis. Similar features are found in the Miocene hominoid Afropithecus turkanensis. Their presence is the first good evidence of a strong phenetic link between the Oligocene and Miocene hominoids of Africa. A comparison of trait lists emphasizes the similarities of the two fossil species, and leads us to conclude that the two fossil genera share many primitive facial features. In addition, we studied facial morphology using finite-element scaling analysis and found that the two genera show similarities in morphological integration, or the way in which biological landmarks relate to one another in three dimensions to define the form of the organism. Size differences between the two genera are much greater than the relatively minor shape differences. Analysis of variability in landmark location among the four Aegyptopithecus specimens indicates that variability within the sample is not different from that found within two samples of modern macaques. We propose that the shape differences found among the four Aegyptopithecus specimens simply reflect individual variation in facial characteristics, and that the similarities in facial morphology between Aegyptopithecus and Afropithecus probably represent a complex of primitive facial features retained over millions of years.

Animals↗
PubMed1991

Growth of the cranial base in craniosynostosis.

The configuration of the neurocranium has long been used as a diagnostic tool in assessing infants with abnormal head shape. In the case of craniosynostosis, a characteristic shape is caused by a constraint placed on growth of the neurocranium by prematurely closed sutures and secondary accommodation to that constraint. This investigation is a preliminary test of our hypotheses of growth of the cranial base under these constraints. Three dimensional landmark coordinate data were collected from pre-, peri-, and postoperative CT scans of eleven patients from The Cleft Palate and Craniofacial Deformities Institute, St. Louis, MO. These data were used in two sets of analytical comparisons. Comparisons of preoperative and perioperative morphology were taken to represent preoperative growth, while comparisons of perioperative to postoperative CT scans represent postoperative growth. Finite-element scaling analysis (FESA) and Euclidean distance matrix analysis (EDMA) were used to make these comparisons. Our results show that in cases involving premature closure of the metopic, sagittal, and bilateral coronary sutures, predictions about growth of the cranial base made prior to analysis prove correct. In these forms of craniosynostosis there are characteristic and consistent changes in the cranial base in both pre- and postoperative growth. Preoperative and postoperative growth in patients diagnosed with unicoronal synostosis show a greater degree of individual variability and do not follow a predictable pattern.

Cephalometry↗
PubMed1990

Analysis of craniofacial growth in Crouzon syndrome using landmark data.

Finite-element scaling analysis (FESA), generalized procrustes analysis (GPA), and Euclidean distance matrix analysis (EDMA) are applied in a two-dimensional study of craniofacial growth in normal children and those affected with Crouzon syndrome. Longitudinal data are used and growth is measured as change local to 10 craniofacial landmarks. Although details of the results vary among the methods, all 3 methods determine Crouzon growth to be different from normal. Nuances of the methods, especially the use of superimposition in GPA and lack of superimposition in 2 others are partly responsible for the varying results. Although Crouzon craniofacial morphology is often obvious at birth, this study demonstrates that there are general differences between normal postnatal growth patterns and those of the Crouzon individual. These patterns of malgrowth are in part responsible for the adult morphology of the Crouzon craniofacial complex.

Adolescent↗
PubMed1989

Microtia and associated anomalies: statistical analysis.

Terms such as oculoauriculovertebral dysplasia, Goldenhar syndrome, and hemifacial microsomia have been used to describe microtia with specific combinations of other craniofacial anomalies. Microtia is also observed with anomalies of postcranial structures. Statistical studies were performed on 297 patients with microtia and other anomalies to identify subgroups of patients representing previously described or new associations. Analysis identified 15 subgroups of patients with specific patterns of anomalies. Log-linear analyses of cranial and postcranial variables demonstrated a positive association between mandibular hypoplasia and cervical spine fusion, which was, in turn, positively associated with other spine anomalies (P less than .02) and other skeletal anomalies (P less than .001). Although unilateral microtia was commonly observed with mandibular hypoplasia, mandibular hypoplasia was negatively associated with bilateral microtia. Many of the associated anomalies were of structures not derived from the 1st and 2nd branchial arch neural crest. However, most associated anomalies were of structures derived from migratory cell populations or populations undergoing differentiation prior to migration between the 19th and 24th day post-fertilization (neural crest, ectodermal placode, mesoderm, surface ectoderm). These findings suggest that many different cell populations may be disturbed in the pathogenesis of microtia in association with other anomalies. The timing of the pathogenetic event may determine the specific pattern of associated anomalies.

Abnormalities, Multiple↗
PubMed1989

Applications of finite-element scaling analysis in primatology.

The study of biological shape in three dimensions using landmark data can now be accomplished using several alternative methods. This report focuses on the use of finite-element scaling analysis in primate craniofacial morphology. The method is particularly useful in its ability to localize the differences between forms, thereby indicating those loci that differ most between specimens. Several examples of this feature are provided from primatological research. Particulars of the methods are also discussed in an attempt to provide the reader with cautionary knowledge for prudent application of the method in future research.

Animals↗
PubMed1988

Craniofacial growth in apert syndrome as measured by finite-element scaling analysis.

A new tool for the study of biological form change is applied in a comparison of craniofacial growth in normal children and those affected with Apert syndrome. Using finite-element scaling analysis, the magnitude of size change during postnatal growth in the Apert sample was determined to be generally less than normal, and the magnitude of shape change was generally greater than normal. No consistent, statistically significant, alteration from normal growth was defined in the Apert sample, however. There appears to be no consistent effect on general cell and tissue proliferation in Apert syndrome. Rather, specific subpopulations of cells and tissues may be affected differentially over time.

Acrocephalosyndactylia↗
PubMed1987

Comparative study of normal, Crouzon, and Apert craniofacial morphology using finite element scaling analysis.

Finite element scaling analysis is used to study differences in morphology between the craniofacial complex of normal individuals and those affected with the syndromes of Apert and Crouzon. Finite element scaling quantifies the differences in shape and size between forms without reference to any fixed, arbitrary registration point or orientation line and measures the amount of form change required to deform one object into another. Two-dimensional coordinates of landmarks digitized from annual sets of cephalometric radiographs were used in the analysis. A simple tabulation shows no difference in variances between the normal and pathological samples. A test of mean differences depicts the Apert and Crouzon morphologies as significantly different from normal. The Apert palate differs from normal in shape in the older age groups analyzed, and palatal size differences are most common at the posterior nasal spine. The Apert pituitary fossa and basi-occiput are significantly larger than normal. The Crouzon pituitary fossa is also larger than normal, but the difference is not always significant. The typical morphology of the Crouzon nose is due more to differences in shape than size. The Crouzon basi-occiput is significantly smaller than normal. An age association of the differences between the normal and pathological craniofacies was found in Apert syndrome but not in Crouzon syndrome. Apert syndrome is characterized by a more homogeneous pattern of craniofacial dysmorphology from 6 months to 18 years of age than Crouzon syndrome.

Acrocephalosyndactylia↗
PubMed1986

Quantitative genetics of cranial nonmetric traits in randombred mice: heritability and etiology.

Cheverud and Buikstra (1981) demonstrated a tendency for nonmetric traits representing the number of foramina to have lower heritabilities than those representing hyperstotic or hypostotic traits in a sample of rhesus macaques. Based on this observation, Cheverud and Buikstra hypothesize that differences in the heritability of the two sets of traits may be due to differences in trait etiology. This study addresses the proposed relationship between trait heritability and etiology. Heritability values are calculated for 35 cranial nonmetric traits in a sample of 320 randombred mice using analysis of variance. The results are minimally consistent with the etiological hypothesis, but only 4 of the 35 traits showed statistically significant heritability values. These results are discussed with reference to the assumption that nonmetric traits have a strong genetic component. It is concluded that the developmental pathways that genetic variation traverses before being expressed in the form of nonmetric traits must be understood before variation in nonmetric traits can be used to its fullest potential.

Animals↗
PubMed1986

Finite element scaling analysis of human craniofacial growth.

The study of form change is central to traditional cephalometric research. Unfortunately, traditional cephalometric studies operate within systems of measurement that are based on registration and orientation. Measurements produced in registered systems are insufficient for the craniofacial biologist who is interested in locating morphological differences between forms. In this article we apply a registration-free method called finite element scaling analysis in a study of the form change occurring during growth of the normal human craniofacial complex. The method provides form change data that can be summarized at various morphological levels. Twenty normal male individuals are used to analyze the form change that occurs from age 4 to ages 5, 7, 8, 9, 10, 12, 13, and 15 years. The magnitude and direction of growth expressed as shape and size change specific to craniofacial landmarks are presented. Although exceptions occur, our analysis shows that localized size change is, on the average, greater than localized shape change. The relation between size and shape change during growth shows allometry (shape change increasing during growth along with size change) but at a lesser magnitude and slower rate. We conclude that although shape change occurs throughout ontogeny, the magnitude and rate of shape change in relation to size change diminishes as age increases. This analysis represents new insights into the understanding of human craniofacial growth at various levels of morphological integration.

Adolescent↗
PubMedDate not supplied

A quantitative genetic analysis of localized morphology in mandibles of inbred mice using finite element scaling analysis.

We analyzed patterns of mandibular genetic and phenotypic morphological integration and the relationship of genealogy to interstrain molecular and morphological differences in ten inbred strains of mice. Positions of mandibular landmarks in two-dimensional space were used to construct a finite element mesh for each individual, then all individuals from the ten strains were compared to the average mandible from a standard strain (SEA/GnJ). Measures of size and shape associated with finite element scaling analysis were then used in a quantitative genetic analysis of mandibular variation. Significant genetic variation for mandibular size and shape was uncovered. Patterns of both genetic and phenotypic correlation for measures of landmark-specific sizes were consistent with models of morphological integration based on the developmental origin of parts of the mandible and on the effects of muscle attachment on mandibular morphology. Shape differences local to particular landmarks did not show these forms of morphological integration. Although interstrain distances based on local shape magnitudes were significantly correlated with genealogical relationship, distances based on local size differences were not. Even higher than the correlation of genealogy with distances based on local shape magnitude was the genealogical-molecular distance correlation. Patterns of morphometric mandibular variation corresponded to expected effects of epigenetic developmental processes. Also, when detailed shape differences were considered, morphology served as a rough guide to genealogy, although molecular distances showed a stronger relationship.

Animals↗