Descriptive and topographic anatomy of the accessory infraorbital foramen. Clinical implications in maxillary surgery.

AIM: Study of frequency and position of accessory infraorbital foramen in a large craniological sample. METHODS: A sample of 1 064 skulls from the craniological collection of the Department of Anatomy, Pharmacology and Forensic Medicine of the University of Turin (Italy) was investigated. RESULTS: Accessory infraorbital foramen was found in 4.7% of the skulls (5.4% in male and 4.26% in female skulls) with a higher frequency on the left side, both in male and in female skulls. CONCLUSION: These results increase our knowledge of the interindividual anatomic variability of the infraorbital region and can be of help for the maxillo-facial surgeon, especially in trunk block of the infraorbital nerve.

Dental microwear. Morphological, functional and phylogenetic correlations.

Dental wear, at first considered a pathological condition, is now regarded as a physiological mechanism of teeth adaptation to continuous masticatory stresses. Excessive wear is limited by characteristic structural adaptations of dental hard tissues showing a phylogenetic trend and specialisation. Enamel is the main tissue subjected to wear; however, advanced enamel wear exposes increasingly large areas of dentine. Enamel hardness and anisotropy are the major factors contrasting wear and microfractures. Anisotropy is mainly related to the different orientation of prism bundles (and of hydroxiapatite cristals). Enamel wear development is also related to differences in microhardness, density, mineral composition and protein distribution. Masticatory loads distributed along the enamel-dentine junction uniformly disperse in the underlying dentine. In spite of its structural characteristics, dentine is relatively isotropic by the functional point of view. Even if its lower hardness opposes less efficaciously to wear, its biomechanical characteristics successfully contrast microfractures. The study of microwear (namely the microscopic analysis of worn dental surfaces) can be made both on original surfaces and on high definition silicone-resin replicas. Scanning electron microscope observations allow identification of surface damage (microtraces) produced by different physical and chemical agents. Microwear analysis may provide indications about alimentary and non alimentary habits, masticatory biomechanics and pathological situations (e.g., bruxism).

Subvertical grooves of interproximal facets in Neandertal posterior teeth.

Subvertical grooves, located on the interproximal facets of most Neandertal posterior teeth, are less frequently noted on the teeth of other hominids, including modern humans. These grooves, 0.1-0.5 mm in width, are strictly localized within the facet area. Scanning electron microscopic (SEM) examination of grooves present on Neandertal teeth from Caverna delle Fate (Liguria, Italy) and Genay (Côte d'Or, France) demonstrated that they were produced during the life of these individuals. Characteristics of the groove surface suggest an erosion-abrasion mechanism of formation. These grooves, which developed in parts of the dentition exposed to marked stress, originated in areas characterized by changes in the orientation of enamel prism bundles (i.e., Hunter-Schreger bands). Observations carried out on modern human molars showed a subvertical disposition of these bands near interproximal ridges facilitating subvertical microfractures. Possible correlations between enamel structure, masticatory stress, and interproximal groove formation in Neandertals are discussed.

The collection of human skulls and postcranial skeletons at the department of human anatomy of the University of Torino (Italy).

The human osteological collection at the Department of Human Anatomy, University of Torino, Italy, has recently been rearranged and recatalogued, and is now available for study. It comprises 1,064 modern skulls of known sex (384 males and 680 females); the age is also recorded in 712 cases. Of these skulls, 162 are from persons aged less than or equal to 20 years of known sex. A few skulls also have the postcranial skeleton (35 males and 39 females). The collection includes microcephali and hydrocephali, and also some prehistoric, Etruscan, Phoenician, Egyptian, Greek, Roman, Ancient Jewish, and Lombard skulls. A brief catalogue is provided.

[Homo- and contralateral changes in muscle cholinergic enzymes following immobilization in the rabbit]. / Modifications homo- et contro-latérales des enzymes cholinergiques dans les muscles après immobilisation, chez le lapin.

Changes in ChAc and AChE activity were observed in the caput longum of the triceps of both forelimbs of 45-day-old rabbits when the left antebrachium was immobilized in total extension on the brachium for periods of up to 60 days. Enzyme determination on the proximal, ventral and distal portions showed a correlation between quantitative changes in AChE activity, and reappearance of its terminal activity demonstrated histochemically by other workers with the same experimental model.

New European fossil hominid material from an Acheulean site near Rome (Castel di Guido).

New fossil hominid material recovered from an Acheulean Italian archeological site is reported. It consists of two portions of femora, an occipital fragment, a fragmentary right maxilla, and a portion of parietal. Each specimen is described in detail and measurements are given. On the basis of the morphology, which includes primitive traits reminiscent of Homo erectus, and of the archeological, paleontological, and stratigraphical association, these new fossils are referred to the early European group.

Omo- and contralateral changes in cholinergic enzymes in muscles following immobilization, in the rabbit.

Changes in ChAc and AChE activity were observed in the caput longum of the triceps of both forelimbs of 45-day-old rabbits when the left antebrachium was immobilized in total extension on the brachium for periods of up to 60 days. Enzyme determinations on the proximal, ventral and distal portions showed a correlation between quantitative changes in AChE activity, and the reappearance of its terminal activity demonstrated histochemically by other workers with the same experimental model.

A developmental model for studying choline acetyltransferase transport in chick motoneurons.

The proximodistal axonal transport of choline acetyltransferase (ChAc) has been studied in the chick sciatic nerve in the absence of any experimental manipulation. The phenomenon utilized by us is a physiological transient fall in the activity of ChAc. This fall occurs in most areas of the chick central nervous system after hatching, and moves toward the periphery along the nerves. Having ruled out the presence of transient inhibitors, the movement of the fall towards skeletal muscles has been considered to correspond to the proximodistal transport of ChAc. The calculated average velocity is 7.86 mm/day, corresponding to the slow rate of transport. Nevertheless, the kinematics study suggests that the velocity varies along the nerve from a state of rest to an intermediate rate of transport (16 mm/day). The possible influence of variations in the resistance of the conductor on these changes in velocity is discussed.

[Cholinesterase of the chick optic lobe. Molecular forms and behavior after deafferentation]. / La colinesterasi nel lobo ottico di pulcino. Forme molecolari e comportamento dopo deafferentazione.

The behaviour of AChE and ChE has been studied quantitatively in the chick optic lobe (tectum and nuclei) under normal conditions and after deafferentation. Eye extirpation was carried out at the 1st day after hatching. Both in the tectum and in the nuclei, a low decrease in specific activity was observed, in comparison with the control. Nevertheless, when the total activity is calculated, a significant decrease is evident, owing to marked underdevelopment of the deafferented lobe. In the normal chick lobe, 2 molecular forms of AChE (6.58 and 11S) have been observed. The distribution of these 2 forms is not altered by eye extirpation, until at least 120 days of age.

[Comparative action of chronic injection of alpha toxin from Naja nigricolis and of botulinum toxin A on the development of chick embryo dorsal and ventral spinal roots]. / Effets comparés de l'injection chronique de toxine alpha de Naja nigricollis et de toxine botulinique A sur le développement des racines dorsales et ventrales de la moelle épinière d'embryons de poulet

The chronic injection of high doses of alpha toxin from Naja nigricollis or botulinum toxin type A in the yolk sack of developing Chick embryos causes a selective decrease of the number of fibers in the ventral roots of the spinal nerves; at the concentrations needed this reduction is more important with the alpha toxin than with the botulinum toxin.

Effects of a snake alpha-neurotoxin on the development of innervated skeletal muscles in chick embryo.

The evolution of the cholinergic (nicotinic) receptor in chick muscles is monitored during embryonic development with a tritiated alpha-neurotoxin from Naja nigricollis and compared with the appearance of acetylcholinesterase. The specific activity of these two proteins reaches a maximum around the 12th day of incubation. By contrast, choline acetyltransferase reaches an early maximum of specific activity around the 7th day of development, and later continuously increases until hatching. Injection of alpha-toxin in the yolk sac at early stages of development causes an atrophy of skeletal and extrinsic ocular-muscles and of their innervation. In 16-day embryos treated by the alpha-toxin, the endplates revealed by the Koelle reaction are almost completely absent. The total content and specific activities of acetylcholinesterase and choline acetyltransferase in atrophic muscles are markedly reduced.