HASH(0x1a80c580)

Objective: To quantify longitudinal cranial base growth from prepubertal through postpubertal stages of development, as defined by biological indicators of individual skeletal maturity (cervical vertebral maturation - CVM) method and to determine if there is sexual dimorphism resulting from cranial base growth. Design: A longitudinal cephalometric study. Setting: The Dental School of Paulista University, Brazil. Participants: 36 subjects (21 females, 15 males) who were part of a longitudinal growth study and exhibited normal facial and normal vertical growth patterns. Methods: Growth maturation of cervical vertebrae stages was assessed by two examiners independently. Cranial base measurements were carried out by one individual and repeated after one month. The growth increments over time were assessed with the one-way repeated-measures analysis of variance and post hoc Tukey multiple comparisions. Results: There were no significant gender differences. There was a significant increase in all cephalometric measures between the different time points. Ba-Na showed the greatest amount of growth (mean change=2.8 mm). From T2-T3, the greatest amount of growth was found for Se-Na (mean change=3.4 mm) and the lowest for CC-Na (mean change=1.4 mm). Comparing overall changes (T1-T3) all the measurements showed statistically significantly increases (P<0.05). For all comparisons of between-stage changes the cranial base grew more than 2.0 mm during the pubertal growth. Conclusions: Linear variables of cranial base showed significant growth during pubertal stages (pre-peak, peak and post-peak). No significant differences.

OBJECTIVE To compare traditional superimposition on sella turcica and the anterior cranial base (SACB) to superimposition referenced at the occipital condyle (I-point) for demonstrating craniofacial growth and development. MATERIALS AND METHODS Tracings for ages 8, 10, 12, 15 and 18 were chosen from the Bolton Standards of Dentofacial Developmental Growth to compare superimposition with the traditional longitudinal reference at SACB (anterior curvature of sella turcica and anterior cranial base) to reference at I-point on the antero-inferior contour of the occipital condyles in norma lateralis. The serial tracings were superimposed using both the sagittal and postero-anterior (PA) tracings. Incremental growth of landmarks was measured in relation to Cartesian coordinates and compared between the superimposition methods. RESULTS Sagittal and PA tracing superimpositions displayed an average 7 mm greater cephalad movement of landmarks, an average 2.4 mm greater ventral movement, and comparable transverse dimension with superimposition referenced at I-point as compared to the SACB reference. CONCLUSION I-point superimposition demonstrates physiologic growth patterns concealed by traditional registration at sella turcica. The evolution of superimposition on SACB was based on convenience and reproducibility. Fundamental principles of bone development are consistent with the occipital condyles as a more biologic reference for relative craniofacial growth. Actual vertical growth is believed to be greater than displayed in this study, due to the cross-sectional and blended nature of the sample.

This retrospective study tests the hypothesis that superimposition referenced at the occipital condyles (defined as I-point, I-curve) and oriented to the anterior cranial base (ACB) will display a growth pattern that is more consistent with independent evaluations, such as the Melsen necropsy specimens and the Bjork implant studies, when compared with traditional superimpositions referenced at sella turcica. Twenty-eight sets of serial lateral cephalometric radiographs were selected from an archived growth study. The apparent facial growth was compared using polar coordinate analysis from superimposition tracings of the serial films for each subject. The two superimposition methods were compared. The traditional method, ACB registered on the anterior curvature of sella turcica, versus registration on I-point while maintaining ACB parallel. I-point registered superimpositions consistently displayed a facial growth pattern that was more consistent with the classic necropsy specimens of children and the cephalometric studies superimposing on implant markers. Traditional ACB superimposition suggests that airway is restricted by normal growth. This apparent physiologic artifact does not occur when superimpositions are registered on I-point. Sella turcica displays vertical movement that is consistent with brain growth. These data indicate that registration on I-point is a more accurate physiologic representation of facial growth than the traditional ACB superimpositions. When compared with the traditional registration at sella turcica, I-point superimposition better elucidates physiologic growth patterns. As cephalometrics evolve from a two to a three dimensional science, it is important to use a more biologically valid registration for evaluating therapeutics and facial growth patterns.

OBJECTIVE Responses of spheno-occipital synchondroses to direct tensile stress have not been identified before. This study was, therefore designed to evaluate expression of PTHrP, and thickness of hypertrophic zone in spheno-occipital synchondroses in response to such stress, using mouse in vitro model. METHODS Spheno-occipital synchondroses together with adjacent structures were excised from fifty-five 2-day-old mice that were randomly assigned to 6 control and 5 experimental groups for 5 experimental periods (n=5). In the experimental groups, tensile force of 0.2g was applied across the synchondroses, using helical springs. In 5 control groups, the springs were made inactive. Both groups were then cultured for 6, 24, 48, 72 h and 7 days. Another control group was cultured without any springs for 7 days to compare with natural growth of the synchondroses from a group of five 9-day-old mice. Alcian blue-PAS staining was used to study growth of the synchondroses; immunohistochemical staining to identify PTHrP and type X collagen expression. The area of PTHrP expression and thickness of hypertrophic zone, demarcated by type X collagen expression, were measured. RESULTS Quantitative analysis showed that PTHrP expression increased significantly at hour 24 of the force application in the experimental group (p<0.05), then reduced from hour 24 to 72 with a significant drop from hour 24 to 48 (p<0.01); and the thickness of hypertrophic zone significantly increased at hour 48 (p<0.01). CONCLUSIONS Our findings suggested that the growth of spheno-occipital synchondroses could be modified by tensile stress; and a light continuous force could enhance its growth, as evidenced by an increase in PTHrP expression and thickness of hypertrophic zone.

Several cephalometric studies and case reports have described the effects of treatment with a maxillary protraction appliance (MPA) and chincap appliance. The purpose of this investigation was to identify differences in the response to treatment with a combined MPA and chincap in skeletal Class III patients with different vertical skeletal morphologies: short-(low mandibular plane angle) and long-(high mandibular plane angle) face types. The cephalograms used in this study were of 42 Japanese girls at the beginning of treatment (T0, mean age 10.1 years) and at removal of the appliance (T1, mean age 11.5 years). The subjects were divided into two groups (short and long face) according to the inclination of the mandibular plane at T0. Total anterior face height, upper and lower face height, occlusal plane, and gonial angle were significantly larger in the long-face group at T0. In both groups, significant increases in SNA, maxillary size (A'-Ptm'), and ANB were noted during treatment. Compared with the long-face group, the short-face group showed greater forward displacement and size increment of the maxillary body, while there were no significant differences in changes in mandibular size or position between the two groups. These results indicate that the vertical dimensions of the craniofacial skeleton are important factors in the orthopaedic effects of a MPA and chincap and the prognosis for skeletal Class III patients.

Studies evaluating maxillary and mandibular skeletal and dental positions and the vertical components of Class II patients have reported conflicting results. In addition, no common results have been found regarding cranial base configurations. However, few studies have evaluated nongrowing subjects. The aim of this study was to establish whether patients with skeletal and dental Class II division 1 malocclusion have specific craniofacial features. For this, 40 nongrowing females were evaluated cephalometrically. Wide variations were observed for almost all measurements of Class II division 1 patients. However, a posteriorly positioned and rotated mandible, protrusive mandibular incisors, and an increased cranial base angle were all mean characteristics of Class II division 1 patients.

The petro-occipital fissure (POF) lies within a critical interface of cranial growth and development in the posterior cranial fossa. The relationships between skeletal and soft tissues make this region especially important for examining biomechanical and basic biologic forces that may mold the cranial base and contribute to significant clinicopathologies associated with the structures located near the POF. Therefore, this study investigates the POF in adults in both preserved human cadavers and dried crania in order to determine if developmental changes can be observed and, if so, their value in age assessment as a model system for describing normal morphogenesis of the POF. This study demonstrates that tissue within the POF undergoes characteristic changes in ossification with age, the onset of which is considerably later than that of other synchondroses of the cranial base. Statistically, there is a moderate to strong correlation between age and stage of ossification within the POF. Further, male crania were observed to reach greater degrees of ossification at a younger age than female crania and that individual asymmetry in ossification of the tissue within the POF was not uncommon. An understanding of the basic temporal biological processes of the POF may yield insight into the development of clinicopathologies in this region of the cranial base.

In this study, the amount and direction of displacement of reference landmarks located on the cranial base and face were examined and compared according to the superimposition methods of Björk (method A), Steiner (method B), and Ricketts (method C). The material consisted of cephalometric and hand-wrist films of 40 nontreated growing individuals obtained at the beginning (T1) and at the end of the observation period (T2). Hand-wrist films were used to evaluate the skeletal maturation of the subjects. The displacement of each landmark was measured according to each superimposition method, and the amounts of displacement in each method were evaluated by paired t-test. The repeated measurement analysis of variance test was used to compare the variances of the changes among the methods. Significant changes were observed in landmarks (sella, nasion, basion, pterygomaxillare), which used as references for superimpositions. The direction of displacement of sella and pterygomaxillare points was different among the methods. In the horizontal plane, although most landmarks were displaced in a similar manner in the Björk and Ricketts methods, the vertical displacement of all the landmarks was different. The horizontal displacements of basion, condylion, and gonion were similar according to all three methods. These results indicate that differences regarding the superimposition methods should be taken into consideration in the evaluation of the changes due to growth or treatment.

The purpose of this study was to elucidate the nature of human craniofacial growth by means of finite element method (FEM), and to compare the results with the current concept derived from morphometric studies with roentgenographic cephalometry (RCM). Lateral cephalograms were taken of 20 males and 20 females, and traced on acetate paper. On the tracing, the craniofacial complex was divided into seven areas or elements. Growth analysis was executed with FEM for changes in the size and shape of each area during six developmental periods from 4 to 18 years old. The size change in the male group exhibited a peak from 10 to 12 years old for the cranial base and upper facial skeleton, from 8 to 10 years old for the maxillary complex, and from 12 to 14 years old for the mandible. On the other hand, in the females, the size change was almost invariable from 4 to 12 years old and completed suddenly at 12 years old, which was earlier by a few years than in the males. An interesting finding is that changes in the size and shape were the most substantial in the maxillary complex, followed by those in the mandible, and the smallest in the cranial base and upper facial skeleton. It is shown that growth of the cranial base lasted up to 14 years old and the maxillary complex exhibited the greatest growth changes in the size among various anatomic structures. These findings may provide a new concept of human craniofacial growth, somewhat different from the previously established principles by RCM.

Various path loss models have been developed for solar blind non-line-of-sight UV communication links under an assumption of coplanar source beam axis and receiver pointing direction. This work further extends an existing single-scattering coplanar analytical model to noncoplanar geometry. The model is derived as a function of geometric parameters and atmospheric characteristics. Its behavior is numerically studied in different noncoplanar geometric settings.

OBJECTIVE To evaluate the craniofacial morphology of patients with isolated cleft palate in the mixed dentition after palatoplasty. METHODS Twenty patients (7 to 11 years old) with isolated cleft palate in the mixed dentition were selected. The control group comprised 35 age-matched non-cleft children without orthodontic treatment. Cephalometric analysis was carried out to evaluate craniofacial morphology. RESULTS The mean values of total cranial base length, maxillary depth, mandibular effective length in cleft patients were 86.48 mm, 44.79 mm and 65.45 mm, respectively. Those in control group were 91.27 mm, 48.84 mm and 70.49 mm, respectively (P < 0.001). CONCLUSIONS Underdeveloped maxilla and class III skeletal profile were presented in patients with isolated cleft palate.

It is an established assumption that the inheritance of intracellular organelles into daughter cells is not left to chance. A recent study by Rob Jensen and coworkers provides a new link between a protein required for the inheritance of nuclei in yeast with the positioning and morphology of the mitochondria.

Uranium-series method has been applied to continental carbonate deposits from Constantina, Seville, in Spain. All samples analysed were impure carbonates and the leachate-leachate method was used to obtain activity ratios in carbonate fraction. Leachate-residue methods were applied to one of the samples in order to compare with leachate-leachate method, but leachate-residue method assumptions did not meet and ages resulting from leachate-residue methods were not valid. Ages obtained by leachate-leachate method range from 1.8 to 23.5ky BP and are consistent with stratigraphical positions of samples analysed. Initial activity ratios for uranium isotopes are practically constant in this period, thus indicating that no changes in environmental conditions occur between 1.8 and 23.5ky period.

Erdelyi's "unified theory of repression" attempts to rehabilitate psychoanalytic doctrine by exaggerating its compatibility with the findings of cognitive science. In addition, Erdelyi treats Freud's writings as holy writ, any portion of which can be quoted to prove a point. He also relies on a long-discredited account of Freud's "seduction theory" and ignores important links between Freudian assumptions and our recent recovered memory movement.

The colour-changing stimulus paradigm is based on a tacit assumption that kinematic attributes (velocity, movement direction) do not affect the detection of colour change (). In this study three experiments are reported that clearly demonstrate that the time needed to detect changes in colouration of a moving stimulus becomes shorter with its velocity. The reduction of reaction time with increase of velocity is a purely kinematic effect independent on the reduction of reaction time caused by the stimulus uncertainty effects. It is concluded that colour coding mechanisms are not totally ignorant about movement parameters.

The growth dynamics of filamentary microbial colonies is investigated. Fractality of the fungal or actinomycetes colonies is shown both theoretically and in numerical experiments to play an important role. The growth observed in real colonies is described by the assumption of time-dependent fractality related to the different ages of various parts of the colony. The theoretical results are compared to a simulation based on branching random walks.

Simulator-based research has shown that pilots cognitively tunnel their attention on head-up displays (HUDs). Cognitive tunneling has been linked to object-based visual attention on the assumption that HUD symbology is perceptually grouped into an object that is perceived and attended separately from the external scene. The present research strengthens the link between cognitive tunneling and object-based attention by showing that (a) elements of a visual display that share a common fate are grouped into a perceptual object and that this grouping is sufficient to sustain object-based attention,(b) object-based attention and thereby cognitive tunneling is affected by strategic focusing of attention, and (c) object-based attention is primarily inhibitory in nature.

In this study, a class of dynamic models based on metabolic reaction pathways is analyzed, showing that systems with complex intracellular reaction networks can be represented by macroscopic reactions relating extracellular components only. Based on rigorous assumptions, the model reduction procedure is systematic and allows an equivalent 'input-output' representation of the system to be derived. The procedure is illustrated with a few examples.

Abstract A heavily pigmented tumor was removed from the lateral, perilimbal, bulbar conjunctiva of a bay Thoroughbred horse. Excision was incomplete and the base of the tumor was lasered on the assumption that the tumor was a melanoma. No other ophthalmic lesions were seen. Histology showed the mass to be a pigmented squamous cell carcinoma (SCC). The prognosis and recommended treatment protocols are different for SCC and melanoma. This is, to the best of our knowledge, the first report of an ocular, pigmented SCC in the veterinary literature.