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Biomedical subjects

A Demirjian

Publications and source records attributed to A Demirjian.

At least 19 recordsLinked to original sources
PubMed2001

A single H:CDR3 residue in the anti-digoxin antibody 26-10 modulates specificity for C16-substituted digoxin analogs.

We constructed Fab libraries of bacteriophage-displayed H:CDR3 mutants in the high-affinity anti-digoxin antibody 26-10 to determine structural constraints on affinity and specificity for digoxin. Libraries of mutant Fabs randomized at five or 10 contiguous positions were panned against digoxin and three C16-substituted analogs, gitoxin (16-OH), 16-formylgitoxin and 16-acetylgitoxin. The sequence data from 83 different mutant Fabs showed highly restricted consensus patterns at positions H:100, 100a and 100b for binding to digoxin; these residues contact digoxin in the 26-10:digoxin co-crystal structure. Several mutant Fabs obtained following panning on digoxin-BSA showed increased affinity for digoxin compared with 26-10 and retained the wild-type (wt) Trp at position 100. Those Fabs selected following panning on C16-substituted analogs showed enhanced binding to the analogs. Replacement of H:Trp100 by Arg resulted in mutants that bound better to the analogs than to digoxin. This specificity change was unexpected, as C16 lies on the opposite side of digoxin from H:CDR3. Substitution of wt Trp by Arg appears to alter specificity by allowing the hapten to shift toward H:CDR3, thereby providing room for C16 substituents in the region of H:CDR1.

Amino Acid Sequence↗
PubMed1999

Incremental growth charts for condylar growth between 6 and 16 years of age.

This study provides sex specific reference data for the incremental growth of the mandibular condyle. The results pertain to a mixed-longitudinal sample of 113 males and 108 females followed annually between 6 and 16 years of age (total of 1647 observations). Growth of condylion was evaluated using naturally stable mandibular reference structures. The mean growth curves were estimated by multilevel models using iterative least squares procedures; between subject variation was estimated based on the sample's percentile distributions. Mean yearly velocities of condylar growth for males ranged between 2.1 and 3.1 mm/year. Growth rates decreased during childhood, increased during adolescence, and attained a maximum of 3.1 mm/year at approximately 14.3 years of age. Females showed a more constant rate of condylar growth during childhood (2.0-2.7 mm/year), a smaller adolescent peak (2.3 mm/year) at approximately 12.2 years and rapid deceleration after the peak. These reference data offer orthodontists an objective means of evaluating growth potential and treatment outcome in individual patients. Charts are provided for evaluating condylar growth of individual patients.

Adolescent↗
PubMed1999

Longitudinal post-eruptive mandibular tooth movements of males and females.

Unbiased estimates of post-eruptive eruption and migration of the mandibular teeth for large representative samples are presently unavailable. The purpose of this study was to evaluate pure tooth movements of untreated children and adolescents longitudinally. Lateral cephalograms of 214 French-Canadians, followed bi-annually between 8 and 15 years of age, were traced, and the positions of the mandibular permanent central incisors and first molars were digitized. Temporal changes in tooth position were evaluated relative to naturally stable mandibular reference structures, using the mandibular reference line for orientation. The statistical analyses included t-tests to assess gender differences and Pearson product-moment correlations to evaluate associations. The results showed that the incisors proclined significantly more for males (6 degrees) than females (3 degrees). The incisor tips displayed early mesial movements that were countered by later distal movements. The incisor apex showed a consistent pattern of distal migration between 8 and 15 years. Mandibular arch length decreased over the 7-year observation period. Rates of mesial molar migration accelerated until 11 years of age and then decelerated. There was no significant change in the mandibular occlusal plane angle between 8 and 15 years of age. Incisor eruption showed the greatest rates during adolescence, attaining peaks at approximately 12 years for females and 14 years for males. The molars erupted approximately 5 mm between 8 and 15 years of age. The greatest gender differences occurred at the older ages, with males showing greater eruption potential than females. It was concluded that the mandibular teeth show significant migration and eruption during childhood and adolescence, with gender differences in the amount, direction, and timing of movement.

Adolescent↗
PubMed1995

Multimedia approach to dental education in the 21st century.

Today's technology allows educators to design and create tools that enable teachers and students to work with material from different sources and to attend courses at various sites. The personal computer represents perhaps the greatest boon to this movement by providing a vehicle for "user friendly," interactive, multimedia courseware. A discussion of that courseware, its development and implementation, is provided here.

CD-ROM↗
PubMed1995

Using interactive multi-media to teach the anatomy and pathology of the temporo-mandibular joint.

An interactive multi-media courseware on the Temporo-mandibular Joint is presented. All the latest technological innovations are integrated into this document to make the learning process more enjoyable for the user. We believe that the complex anatomy and physiology of this joint, and mostly its various disorders will be better understood with this interactive multi-media approach. The courseware is intended for continuing education in dentistry and medicine.

Anatomy↗
PubMed1995

Learning medical and dental sciences through interactive multi-media.

Health professionals in various fields of Medicine and Dentistry must acquire comprehensive technological knowledge in order to practice their professions. A large portion of that knowledge cannot be found in a textbook. Examples of this type of information are data gleaned from viewing microscopic slides and dissecting cadavers. In order to fully comprehend an area of study in medicine, the student relies on various resources (often physically unrelated, like the x-ray department and the dissection room). This situation makes the teaching and learning processes much more difficult to accomplish, since the instructor and students have to manipulate multiple media and take the courses in various sites. Today's technology allows us to design and create teaching and learning tools that can alleviate these difficulties. Personal computers are now used to capture and display a vast array of information through many different media: text, sound, images, photographs, illustrations, animation and video. This information can be presented to the user with audio-visual interfaces designed to facilitate efficient communication of ideas. It is controlled primarily by the use of the mouse, at one's own pace. This interactive, multi-media approach to teaching and learning is called "Edutainment" (Education and Entertainment). This demonstration will show how these new tools are used to teach and learn about various subjects related to Medicine, particularly in Dermatology and Dentistry. Several courseware applications were developed, addressing various aspects of the field: Cancers of the Skin, Dental Development, the Temporomandibular joint, the Masticatory Muscles etc. These programs provide anthropological data on growth collected through longitudinal research, diagnosis and treatments of pigmented lesions of the skin, thousands of digitized x-rays accessible through a relational database, the latest imaging technology used to diagnose the temporomandibular disorders, high-quality photographs of dissecting room material of the head and neck region, 3-dimensional animation of physiological principles of the temporomandibular joint movements, digital video of examination techniques, and other valuable resources to the user. The software were developed for both platforms, Macintosh and PC/Compatible, and all of them are in English and French, with some titles available in Spanish. To facilitate their distribution and usage, they were written to hybrid CD-ROMs, i.e., one CD-ROM was produced for each application, containing versions for both platforms in all languages. The CD-ROMs were recorded in our premises. During the presentation, the technical aspects of the development and production of a Multi-media document will be discussed along with the scientific content of the CD-ROM.

CD-I↗
PubMed1993

Longitudinal shape changes of the nasal dorsum.

This investigation quantifies childhood and adolescent growth changes of the upper and lower nasal dorsum and evaluates various aspects of the persons' morphology that relate to shape changes of the dorsum. A longitudinal sample of 37 French-Canadian girls, each having cephalograms at 6, 10, and 14 years of age, was evaluated. The 6- to 10-year interval was chosen to represent childhood growth; the 10- to 14-year interval represented adolescent growth. The upper dorsum rotates upward and forward (counterclockwise) approximately 10 degrees between 6 to 14 years of age. The lower dorsum shows both downward and backward (clockwise) and upward and forward (counterclockwise) rotation average childhood and adolescent changes in angulation were not significant. The results clearly indicate that changes in the nasal dorsum are most closely related to angulation changes of the lower dorsum, particularly during adolescence. The lower dorsum rotates downward and backward in persons who show greater vertical and less horizontal growth changes. Rotational changes of the lower dorsum are most closely related with vertical changes at pronasale.

Adolescent↗
PubMed1992

Childhood and pubertal growth changes of the human symphysis.

Longitudinal growth changes of the human symphysis were evaluated for 75 children (37 males and 38 females) between 6 and 15 years old. Childhood growth was described by mean yearly rates of change between 6 and 10 years for females and between 7 and 11 years for males; pubertal changes pertain to growth between 10 and 14 for females and between 11 and 15 for males. Cephalometric tracings of the mandible were superimposed using stable reference structures. Vertical growth changes, particularly for landmarks located in the upper 20% of the symphysis, were most pronounced. Annual rates of vertical growth ranged between 0.9 mm/yr for the lingual incisor contact point to -0.2 mm/yr for gnathion. Males showed significantly greater rates of vertical growth than females, especially for the upper half of the symphysis. Vertical growth rates were also greater during puberty than during childhood. The horizontal growth changes indicated lingual movement of most symphyseal landmarks. Annual rates of growth were greatest for landmarks located in the upper half of the symphysis. B-point showed the greatest lingual drift. During puberty, the mandibular incisors in females moved lingually as the upper anterior half of the symphysis remodeled; in males, the incisors maintained their horizontal position as the labial sulcus developed.

Adolescent↗
PubMed1991

A new teaching tool for dental and medical schools: multimedia CD-ROM on dental and skeletal development.

Multimedia teaching tools in Medicine are still very rare. Their presentation on a CD-ROM format is part of the emerging technologies in Medical Informatics. The Multimedia material presented here on Dental and Skeletal Development is mostly a Database and a Tutorial. The Database, which contains more than 2000 hand/wrist radiographs, is mostly intended for Pediatricians, Endocrinologists, Forensic Dentists and Physicians, as well as for Orthodontists and Pedodontists. The material is the result of 20-year of Longitudinal Growth study of children in Montreal. In this Multimedia CD-ROM, the research results are used for Medical teaching purposes.

Bone Development↗
PubMed1990

Mandibular growth prediction: mean growth increments versus mathematical models.

The aim of this study was to compare growth predictions obtained by adding mean annual velocities with predictions derived from a polynomial model of the population's growth curve. Given the child's previous measures at 11, 12 and/or 13 years of age, the cephalometric distance sella-gnathion at 15 years was estimated. Based on a sample of 223 boys and girls, the root mean square error decreased from 0.28 cm (males) and 0.18 cm (females) at 11 years, to 0.19 cm (males) and 0.12 cm (females) at 13 years. Root mean square errors were similar between methods, which was due to high correlations between measures across ages. Significantly, predictions based on mean increments were biased. They often over or underestimate growth for children who are larger and smaller than average. The observed bias was due to expected changes of variance associated with growth, which unconditional methods of prediction cannot control for. Predictions derived from growth models are conditional upon the child's size and are, therefore, unbiased.

Adolescent↗
PubMed1989

Modeling longitudinal mandibular growth: percentiles for gnathion from 6 to 15 years of age in girls.

Growth of the cephalometric landmark gnathion is modeled mathematically with multilevel statistical techniques. The findings, pertaining to a mixed longitudinal sample (N = 772) of 105 girls, 6 to 15 years of age, provide the most accurate descriptions of longitudinal mandibular growth presently available. Polar, rather than rectangular, coordinates are used to better distinguish between the amount and direction of growth. The velocity curve for sella-gnathion includes growth spurts during childhood (7.5 years) and adolescence (12.7 years). Growth direction of gnathion changes regularly throughout the age range, indicating a relative increase of vertical over horizontal growth. These reference standards serve as a basis for comparing and better understanding abnormal growth patterns.

Adolescent↗
PubMed1988

Pubertal growth of the cephalometric point gnathion: multilevel models for boys and girls.

Two-level polynomial models are used to summarize the amount Sella-Gnathion (S-Gn) and direction Nasion-Sella-Gnathion (N-S-Gn) of growth changes for the cephalometric landmark gnathion. Growth descriptions pertain to a mixed longitudinal sample of 209 French-Canadian children 10-15 years of age. The boy's growth curve attains mean minimum prepubertal velocity at 10.8 years and maximum pubertal velocity at 14.1 years. The girl's curve follows a cubic pattern, attaining maximum pubertal velocity at 12.1 years. Boys are larger than girls throughout the age range. Variation between-subjects increases with age in a curvilinear fashion. Growth direction of gnathion is more horizontally directed for girls than boys. Small but significant changes in growth direction occur between 10 and 15 years of age.

Adolescent↗