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Chronologic and geographic variability of neurovascular structures in the human mandible.
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OBJECTIVES: To compare the dimensions of mandibular anatomical landmarks of human mandibles of three different chronological periods and seven different geographic regions. METHODS: Cone beam computed tomography (CBCT) images were acquired fromhuman mandibles of three different chronological periods (Neolithic, Medieval and 19-20th Century). The 19-20th Century consisted of seven human mandibular samples from different geographic locations. Image analysis consisted of comparing anatomic variability and dimensions of the mandibular, lingual and incisive canals, mental foramen and their relationship to specific reference teeth as such to determine geographic region and historic period variabilities. RESULTS: Therewere statistically significant differences between the 19-20th Century group andthe Medieval and Neolithic groups. The 19-20th Century group differed significantly in mandibular canal diameter, tooth root length, length of the lateral lingual canal. In addition, the group also differed from the Medieval sample for the lateral lingual foramen diameter and the midline lingual canal length. Furthermore, the prevalence of anatomic variations was significantly different for the geographic samples tested, with double mental foramina significantly more present in the Congolese sample, and significantly more lateral lingual canals noted in Indonesian and Greenland Eskimo samples. CONCLUSIONS: This study suggests that mandibular neurovascularisation may show some geographic as well as historic variation. Further studies on larger data samples are needed to verify this statement, as such that it can be potentially used in anthropology and forensic dentistry. More research is also needed to address whether the geographic and historic variations are linked, as well to investigate evolutionary trends in these structures.
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The Spy VI child: a newly discovered Neandertal infant.
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Spy cave (Jemeppe-sur-Sambre, Belgium) is reputed for the two adult Neandertal individuals discovered in situ in 1886. Recent reassessment of the Spy collections has allowed direct radiocarbon dating of these individuals. The sorting of all of the faunal collections has also led to the discovery of the remains of a Neandertal child, Spy VI. This individual is represented by two mandibular corpus fragments. The left fragment is the most complete and both sides preserve the mental foramen. Four deciduous teeth are associated with these mandibular remains: three incisors and one canine. The lower left canine (Spy 645a) conjoins with the corresponding alveolar socket in the left part of the mandible. Following extant standards, the developmental stage of the preserved teeth indicate an age at death of about one and a half years. In addition to performing a classical morphometric comparative study of the mandible and teeth,we have evaluated the dental tissue proportions using high-resolution microtomographic techniques. Our results show that Spy VI generally falls withinthe Neandertal range of variation. However, this specimen also exhibits particular traits, notably in the dental internal structural organization, whichreveals that variation in the immature Neandertal variation is larger than what was variation currently represented by the available fossil record. These observations demonstrate the need for investigating the frequency and expressionof immature Neandertal traits in fossil anterior teeth, as well as their temporal and geographic variation. Direct radiocarbon dating of the Spy VI specimen has been conducted in two different laboratories. The results of Spy VI confirm the age previously determined for the two adults, making the Spy Neandertal remains the youngest ever directly dated in northwest Europe.
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A study of peritoneal cells from healthy and Schistosoma mansoni-infected mice with special reference to myofibroblasts arising in culture.
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Adherent, trypsin-resistant, peritoneal cells from mice with chronic schistosomiasis mansoni, and from control mice, were cultivated in vitro up to 20 days. Fibroblasts regularly appeared, about 6 days after seeding, in cultures ofthe manyfold more numerous cells from infected mice, concomitantly with a dramatic increase, detected by autoradiography, in the percentage of DNA-replicating cells of the monocyte-macrophage lineage. Peritoneal cells from healthy and from infected mice were fractionated on discontinuous Percoll gradients. Eight cell subsets were harvested in both cases, quantitated, and studied by electron microscopy. Two fractions (2 and 3: 1.041 < densities < 1.060 g/ml) from infected mice were greatly enriched in monoblasts and promonocytes. The cells of the different subsets were seeded separately, trypsin-treated and cultivated in vitro. Cultures of cell fractions 2 and 3 from infected mice contained the majority of the DNA-synthesizing cells and gave regularly rise to fibroblasts. Cultures of the different fractions were used for sequential morphological observations (2-11 days) at the electron microscope level. Early cultures were also used for the ultrastructural detection of the Mac-1 (CD 18/CD11b) surface antigen by gold immunocytochemistry. A few fibroblasts were rarely observed in cultures of fractions 2 and 3 from control mice, while cells with ultrastructural features of myofibroblasts were regularly observed in cultures of the same fractions harvested from mice with chronic schistosomiasis. Fractions 2and 3 from infected mice contained a large number of Mac-1 positive monoblasts. The correlations between the presence of monoblasts, DNA replication in cells ofthe monocyte-macrophage lineage and the appearance of myofibroblasts in culturesof the same fractions derived from infected mice are discussed.
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Transdifferentiation of macrophages into fibroblasts as a result of Schistosoma mansoni infection.
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The possibility of transdifferentiation of macrophages into fibroblasts which could be at the origin of fibrotic tissue in schistosome-infected mice was studied using immunocytochemical techniques. Macrophage cell samples extracted from the peritoneal cavity of schistosome-infected mice were fractionated on a Percoll gradient. The cultures were purified by treatment with a trypsin solution to eliminate any fibroblasts possibly collected along with the macrophages. Immunocytochemical methods were then used to characterize the cells at differentpoints in time. The fibroblastic property of the morphologically transformed cells was confirmed by their positive labeling with the anti-procollagen antibody. However, these cells still possessed the mac-1 and mac-2 antigens which characterize the monomacrophage line.
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