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Biomedical subjects

S Lozanoff

Publications and source records attributed to S Lozanoff.

46 records · Page 3Linked to original sources
PubMed1985

Third trochanter incidence and metric trait covariation in the human femur.

The relationship between third trochanter incidence and femoral metric trait covariation has been investigated in a group of 60 left human femora. The experimental sample was constructed so that one group consisted of 15 male and 15 female femora which displayed a third trochanter and a second group consisted of an equal number of sexed long bones which lacked this trait. A battery of ten femoral measurements was sorted according to main effects and interactions and respective covariance matrices were tested for equivalence. Covariance matrices of sorted variables determined not to be significantly different were initially subjected to both ANOVA and MANOVA and subsequently to a principal component analysis. Covariance matrices determined to be significantly different were subjected to a principal component analysis separately. Results of this study indicate that third trochanter incidence is associated with short femora displaying robust proximal diaphyses. The gluteus maximus muscle may act as a primary factor governing third trochanter expression. Further, this infracranial discrete trait appears well suited for human taxonomy studies.

Analysis of Variance↗
PubMed1985

The effect of lithium carbonate administration on growth in the domestic fowl.

Lithium carbonate is routinely used for the treatment of aggressive behavior disorders in adolescents. The current study was undertaken in order to determine the effect of lithium carbonate administration on growth in a domestic fowl model. The results showed that lithium treatment at a therapeutic level (0.2-2.0 mEq/L) did not significantly alter plasma pH levels, food intake, fecal output or body weight gain. Bivariate and multivariate analysis of tibial dimensions revealed that lithium treatment primarily caused increased growth of proximal epiphyseal height. Allometric analyses indicated that lithium administration increased the growth differential between proximal and distal epiphyses. Two possible mechanisms by which lithium carbonate administration may cause accelerated osseous growth are given.

Animals↗
PubMedDate not supplied

Components of soft tissue deformations in subjects with untreated angle's Class III malocclusions: thin-plate spline analysis.

While the dynamics of maxillo-mandibular allometry associated with treatment modalities available for the management of Class III malocclusions currently are under investigation, developmental aberration of the soft tissues in untreated Class III malocclusions requires specification. In this study, lateral cephalographs of 124 prepubertal European-American children (71 with untreated Class III malocclusion; 53 with Class I occlusion) were traced, and 12 soft-tissue landmarks digitized. Resultant geometries were scaled to an equivalent size and mean Class III and Class I configurations compared. Procrustes analysis established statistical difference (P < 0.001) between the mean configurations. Comparing the overall untreated Class III and Class I configurations, thin-plate spline (TPS) analysis indicated that both affine and non-affine transformations contribute towards the deformation (total spline) of the averaged Class III soft tissue configuration. For non-affine transformations, partial warp 8 had the highest magnitude, indicating large-scale deformations visualized as a combination of columellar retrusion and lower labial protrusion. In addition, partial warp 5 also had a high magnitude, demonstrating upper labial vertical compression with antero-inferior elongation of the lower labio-mental soft tissue complex. Thus, children with Class III malocclusions demonstrate antero-posterior and vertical deformations of the maxillary soft tissue complex in combination with antero-inferior mandibular soft tissue elongation. This pattern of deformations may represent gene-environment interactions, resulting in Class III malocclusions with characteristic phenotypes, that are amenable to orthodontic and dentofacial orthopedic manipulations.

Age Factors↗
PubMedDate not supplied

Soft tissue thin-plate spline analysis of pre-pubertal Korean and European-Americans with untreated Angle's Class III malocclusions.

The purpose of this study was to assess soft tissue facial matrices in subjects of diverse ethnic origins with underlying dentoskeletal malocclusions. Pre-treatment lateral cephalographs of 71 Korean and 70 European-American children aged between 5 and 11 years with Angle's Class III malocclusions were traced, and 12 homologous, soft tissue landmarks digitized. Comparing mean Korean and European-American Class III soft tissue profiles, Procrustes analysis established statistical difference (P < 0.001) between the configurations, and this difference was also true at all seven age groups tested (P < 0.001). Comparing the overall European-American and Korean transformation, thin-plate spline analysis indicated that both affine and non-affine transformations contribute towards the total spline (deformation) of the averaged Class III soft tissue configurations. For non-affine transformations, partial warp (PW) 8 had the highest magnitude, indicating large-scale deformations visualized as labio-mental protrusion, predominantly. In addition, PW9, PW4, and PW5 also had high magnitudes, demonstrating labio-mental vertical compression and antero-posterior compression of the lower labio-mental soft tissues. Thus, Korean children with Class III malocclusions demonstrate antero-posterior and vertical deformations of the labio-mental soft tissue complex with respect to their European-American counterparts. Morphological heterogeneity of the soft tissue integument in subjects of diverse ethnic origin may obscure the underlying skeletal morphology, but the soft tissue integument appears to have minimal ontogenetic association with Class III malocclusions.

Cephalometry↗
PubMedDate not supplied

Midfacial morphology of Koreans with class III malocclusions investigated with finite-element scaling analysis.

The spheno-ethmoidal model of midfacial retrognathia suggests that deficient chondrocytic proliferation in the anterior cranial base is associated with inadequate anterior translation of the midfacial complex resulting, for example, in Class III malocclusions. The purpose of this study was to determine whether the morphology of the midface differed in subjects of diverse ethnic origin exhibiting features associated with Class III malocclusions. Lateral cephalographs of 142 children of Korean or European American descent aged between 5 and 11 years were compared. The cephalographs were traced and subdivided into seven age- and sex-matched groups. Average geometries, scaled to an equivalent size, were generated using Procrustes superimposition and subjected to analysis of variance (ANOVA). Graphical analysis using a color-coded finite-element scaling analysis (FESA) program was used to localize differences in morphology. Results indicated that the mean Korean and European American midfacial configurations differed statistically (P < 0.01), and this difference was maintained at most, but not all, age-wise comparisons. Comparing Korean and European American Class III midfacial configurations for local size-change, FESA analysis revealed that while local increases in size were apparent in the posterior palatal regions, the Korean anterior nasal spine regions were generally smaller. For shape-change, the Korean and European American midfacial configurations were predominantly isotropic. Therefore, heterogeneity in appearance may be influenced by morphological variation of the midfacial complex in subjects of diverse ethnic origin, but features of the anterior cranial base may contribute also to the prevalence and severity of Class III malocclusions in Koreans. Moreover, perturbations in endochondral mechanisms of cranio-mandibular growth, and not maxillary intramembranous methods, may be implicated in the etiology of Class III malocclusions in South East Asians.

Age Factors↗
PubMedDate not supplied

A morphometric analysis of human embryonic craniofacial growth in the median plane during primary palate formation.

As the human primary palate develops between embryonic stages 15 and 18, the facial prominences are part of a rapidly growing craniofacial complex that undergoes extensive morphogenetic change. The purpose of this study was to analyze growth in the medial plane in order to identify regional changes that occur during changes in craniofacial morphology. Photographs of midsagittal sections of 35 human embryos of stages 15 to 19 from the Carnegie Embryology Collection were enlarged, and landmarks were digitized for angular and linear measurements and for finite element modeling (FEM) analysis. The results showed magnitudes and directions of growth required to change average stage 15 morphology to later stages. As the facial and cranial components increased in size, shape change was most pronounced in the posterior cranial and orofacial regions. Increases in cranial linear dimensions were significantly larger than those in the cranial base regions. Between stages 15 and 18, the posterior cranial angle decreased, the forebrain and midbrain rotated superiorly toward the hindbrain, the orofacial angle increased, and the face grew above the thorax. The results suggest that morphogenetic growth changes in the cranial regions are closely associated with facial regions during primary palate formation.

Facial Bones↗
PubMedDate not supplied

Growth and morphogenesis of the human embryonic midface during primary palate formation analyzed in frontal sections.

Although it is recognized that morphology of the craniofacial complex changes during primary palate formation, little information is available about the sites and amounts of growth in different regions. The purpose of this study was to analyze growth patterns of human embryonic heads in frontal sections and to identify regional growth associated with changes in craniofacial morphology and formation of the primary palate. Photographs of frontal sections of 31 human embryos of stages 16 to 19 from the Carnegie Embryology Collection were selected at seven different planes through each head, enlarged and traced, and landmarks were located for computerized morphometric measurements and for finite element modeling (FEM) analyses. Anatomical form change from the initial geometry of the average early stage 16 group to that of later stages was shown by numerical values and graphic displays of regional growth changes during midfacial morphogenesis. Between stages 16 and 19, extensive changes in midfacial morphology occurred as the frontonasal prominence elongated vertically (height increased by seven times) and narrowed to approximately half the width, with more pronounced changes in the anterior nasal region. The brain and the face became vertically separated, and the facial prominences became more frontally positioned relative to the brain. Changes in depth of the face were very limited during this period. The area of the maxillary region increased extensively, particularly in the anterior region, as the maxillary prominences grew forward, lateral to the nasal cavity, to contribute to the primary palate. The lateral nasal prominences increased in size with a predominantly horizontal growth pattern. These patterns of vertical growth of the midfacial tissues, narrowing of the nasal pits and frontonasal prominence, forward growth of the maxilla, and relative separation of the brain and face were identified as predominant features of embryonic craniofacial growth during primary palate development.

Brain↗
PubMedDate not supplied

Computer reconstructions of human embryonic craniofacial morphology showing changes in relations between the face and brain during primary palate formation.

During early development of the human facial region, the craniofacial complex undergoes extensive morphogenetic change. The purpose of this study was to generate computer reconstructions of serially-sectioned embryos in order to illustrate major changes in spatial relations that occur between cranial and facial tissues. Five human embryos of stages 16 to 18 from the Carnegie Embryology Collection, which were used in the frontal morphometric study, were selected to illustrate phases of morphogenesis. Serial photographs of frontal sections were enlarged, traced, and digitized for computer reconstruction. The craniofacial complex was divided into components that were similar to those analyzed in a morphometric study [Diewert VM, Lozanoff S: J Craniofac Genet Dev Biol 1993: 13:162-183] to facilitate visualization of changes in regional components. The major changes observed included changes in form of the brain and its ventral contour above the face; enlargement, elongation, and more ventral positioning of the facial prominences relative to the brain; and forward positioning of the eyes and facial tissues relative to cranial components. As the brain became separated from the face at advancing stages of development, the frontonasal prominences narrowed and became vertically elongated, the lateral nasal prominences enlarged and became medially positioned, and the maxillary prominences enlarged and extended anteriorly. Changes in cranial flexion and lifting up and back of the forebrain [Diewert VM, Lozanoff S: J Craniofac Genet Dev Biol 1993:13:184-192.] appear to contribute to withdrawal of the brain from between the facial prominences during early midfacial development before cartilaginous tissues of the chondrocranium develop.

Brain↗
PubMedDate not supplied

Finite element morphometry of the midfacial complex in subjects with Angle's Class III malocclusions.

The purpose of this study was to determine whether the morphology of the midface differed in normal (Class I) and midfacially-retrognathic (Class III) prepubertal subjects, and to localize differences morphometrically. Lateral cephalographs of 133 European-American children between 5-11 years of age were traced and average geometries, scaled to an equivalent size, were generated based upon seven nodes (pterygoid point, PTS; rhinion, RO; posterior nasal spine, PNS; midpalatal point, MPP; anterior nasal spine, ANS; subspinale, A; and prosthion, Pr). The samples also were subdivided into seven age- and sex-matched groups for morphometric comparisons. Procrustes analysis indicated that the overall midfacial configurations differed statistically (P < 0.05). Therefore, a color-coded finite element (FEM) program was used to localize differences in morphology graphically. Comparing Class I and III groups for size-change, FEM revealed that negative allometry was evident in the posterior half of the midfacial configuration localized between PTS, PNS, and MPP. The anterior half was more isotropic, however, but the anterior-most aspect of the configuration between Pr and RO showed some positive allometry particularly in the premaxillary and incisor regions. For shape-change, major differences in shape over the entire midface were not as evident, with an isotropic midfacial morphology for normal and Class III subjects. It is concluded that an identifiable pattern of deformation is evident for the Class III subjects during the prepubertal growth period. Therefore, midfacial retrognathia associated with Class III malocclusions results, at least in part, from deficient anteroposterior elongation of the midfacial complex allied with deformation of the premaxillary region.

Cephalometry↗