Biomedical subjects
G H Sperber
Publications and source records attributed to G H Sperber.
Fabricating a face: the essence of embryology in the dental curriculum.
The current explosive growth in developmental biology, fuelled by the almost completed sequencing of the human genome, is bound to have a profound impact upon the practice of medicine and dentistry in the twenty-first century. No other discipline more accurately reflects this impact than embryology, which combines the basic and clinical sciences of genetics, ontogeny, phylogeny, teratology, and syndromology into the essence of modern medical and dental practice. The advent of in vitro fertilization, chorionic villus sampling, amniocentesis, prenatal ultrasonography, intrauterine surgery, and stem cell therapy has vaulted the previously esoteric subject of embryology into clinical consciousness. All these aforementioned procedures require an intimate knowledge of the different stages of development. The alphabet soup of acronyms that now peppers papers proclaiming the genetics and characteristics of various growth factors and cytokines (e.g., FGF, TGFalpha) are all based upon an understanding of the developmental mechanisms occurring in the embryo and subsequently in wound healing and oncology. Congenital abnormalities ranging from lethal syndromes to dental malocclusions cannot be diagnosed, treated, cured, or prognosticated upon without a sound conceptualization of embryology. Computer technology has revolutionized the understanding and teaching of embryology by portraying developmental phenomena as three-dimensional model images in sequential depictions of changes proceeding in the fourth dimension of time. Embryology must now form the essential core of the basic sciences in medical and dental curricula. Future dental practice will become rooted in the genetics and morphogenesis of facial fabrication.
3D-reconstruction of craniofacial structures of a human anencephalic fetus. Case report.
It was the purpose of this study to investigate the craniofacial bones, cartilages and major blood vessels of a human anencephalic fetus and to describe the malformations of these structures accompanying this developmental disruption. The head of a 16 week old human fetus with anencephaly was serially sectioned and the craniofacial bones, cartilages and major blood vessels were traced and reconstructed by 3D-computer technology. The sphenoidal, temporal and occipital bones showed severe malformations, whereas the bones of the facial cranium were normally developed. Both internal carotid arteries ended within the cerebro-vascular area with no further branches. The vertebral arteries also ended within the cerebro-vascular area. No arterial circle of Willis was developed. The notochord terminated normally in the sphenoid body. The observations indicate that the possible reason for this malformation was non-closure of the anterior neuropore of the neural tube. The normal termination of the notochord suggests that it had no influence on the pathogenesis of this malformation. The malformations of the temporal and occipital bones are contradictory to the hypothesis of Marin-Padilla (1991) that anencephaly is caused by a maldevelopment of the sphenoidal bone.
International standardization of degrees.
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Odonto-eponymology: historical dental names.
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Pathogenesis and morphogenesis of craniofacial developmental anomalies.
A condensed review of the morphogenetic mechanisms of facial fabrication, providing insights into developmental anomalies of clinical concern. Genetics, epigenetics and regulation of molecular, cellular, tissue and organ formation are being elucidated in normal and dysmorphological patterns. The pathogenesis of craniosynostosis is related to fibroblast growth factor expression. Analysis of a 28-month-old-child's dysmorphic synostotic skull explores possible mechanisms of malformation and deformation.
Cranio-facial skeletal development in three human synophthalmic holoprosencephalic fetuses.
In three human fetuses with synophthalmic holoprosencephaly (8, 14, 23 wks. p.c.) and two normal human fetuses (9 and 13 wks. p.c.) the anatomy of the cranial base, facial cranium and their relation to the notochord was studied using serial histological sections and computer aided three-dimensional reconstruction methods. Mesethmoidal cartilage differentiation was variably deficient in all three holoprosencephalic cases. The premaxillary bones were rudimentary with missing tooth buds. The development of the sphenoid bone was defective in two of the holoprosencephalic cases (8, 14 wks. p.c.). The notochord terminated normally within the sphenoid body in all investigated cases. Our results indicate that in holoprosencephaly there is a general defect in the midline cranial cartilage differentiation rostral to the notochord.
Study of the number of roots and canals in Senegalese first permanent mandibular molars.
A study of 480 extracted first permanent mandibular molars of the Oulof people of Senegal, West Africa, revealed 15 teeth with three roots (3.12%), and 120 teeth with four root canals (25%). An extra root correlated with a sextum lingual tubercle in 20% of cases. Analysis of the pulp chambers revealed a variety of rectangular shapes. Comparison of these anomalies with their incidence in other ethnic groups extends the range of incidence of three-rooted first permanent mandibular molars in the Negroid race. This trait is described for only the second time in a Negroid population. The clinical consequences of root variation in root canal treatment are considered.
Computer graphic three-dimensional reconstruction of normal human embryo morphogenesis.
Three-dimensional computer graphic reconstructions of four human embryos at Carnegie stages 11 to 23 portray the relationships and dimensions of individual organ systems. This paper illustrates the cranial, neural, pharyngeal, gut, vascular and nephric architecture in these developing embryos. This technology can be applied to in situ hybridization and immunohistochemistry to map zones and times of developmental gene activity.
Anatomy of the circle of Willis in three cases of human fetal synophthalmic holoprosencephaly.
In three human fetuses with synophthalmic holoprosencephaly (8, 14, 23 weeks post conceptionem) the circle of Willis was studied using serial histological sections and computer aided three dimensional reconstruction methods. This structure was abnormal in all cases. In two cases the anterior communicating arteries were absent. In all cases the anterior cerebral arteries could not be found. One case showed an incomplete circle with no posterior communicating artery. The results indicate that the malformation of the circle of Willis reflects the malformation of the brain.
Computerized graphic imaging for three-dimensional representation: general principles and applications to embryo/fetal development.
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Pharyngogenesis.
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Confleunce of clinical, theoretical, and laboratory research in syndromology.
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The ethics of embryo experimentation.
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Mirror-image dental fusion and discordance in monozygotic twins.
A pair of monozygotic twins had similar but not identical dental anomalies. One twin had fusion of deciduous mandibular lateral incisor and canine on the left, with normal dentition on the right; the co-twin had right mandibular incisor/canine fusion, with aplasia of the lateral incisor on the left. These findings are discussed in the context of the related phenomena of situs inversus, mirror-imaging in twins, and gradients of severity of anomalies in the four copies of the mandibular developmental dental field.
The enigma of cephalogenesis.
The cascade of developmental events in cephalogenesis is initiated by specific genes being transcribed and translated into polypeptides and proteins that form the structural basis of cells and tissues. These become differentiated into the complex organs of the craniofacies by the actions of signalling transducers, growth factors, and morphogens. Defects of development may be traced back through this sequence to determine the specific etiologic factors responsible for dysmorphogenesis. Molecular biology and embryology are becoming increasingly significant for clinicians.
Dental disease in South African history.
A brief history of the close association of the founding of colonial South Africa with scorbutic dental disease and its prevention is outlined. The impact of civilian dental disease upon British army recruits at the end of the 19th century laid the foundation for military dental corps in the 20th century. The deployment of the first dental field officer by the British army during the Anglo-Boer War (1899-1902) demonstrates a further South African contribution to dental history.