Acta anatomica最新文献

The mysteries of the functions of complex glycoconjugates have enthralled scientists over decades. Theoretical considerations have ascribed an enormous capacity to store information to oligosaccharides. In the interplay with lectins sugar-code words of complex carbohydrate structures can be deciphered. To capitalize on knowledge about this type of molecular recognition for rational marker/drug design, the intimate details of the recognition process must be delineated. To this aim the required approach is garnered from several fields, profiting from advances primarily in X-ray crystallography, nuclear magnetic resonance spectroscopy and computational calculations encompassing molecular mechanics, molecular dynamics and homology modeling. Collectively considered, the results force us to jettison the preconception of a rigid ligand structure. On the contrary, a carbohydrate ligand may move rather freely between two or even more low-energy positions, affording the basis for conformer selection by a lectin. By an exemplary illustration of the interdisciplinary approach including up-to-date refinements in carbohydrate modeling it is underscored why this combination is considered to show promise of fostering innovative strategies in rational marker/drug design.

This study was performed to investigate the occurrence of the coracoclavicular joint in Koreans. Materials used in this study were paired clavicles and scapulae obtained from 102 adult Korean cadavers (61 males, 41 females) ranging from 18 to 97 years in age. The occurrence of the joint was identified by a definite articular facet on the conoid tubercle of the clavicle and also by one on the superomedial surface of the coracoid process of the scapula. To compare the morphometric differences between specimens with and without coracoclavicular joint, the clavicle length, scapular border length, glenoid length, coracoid height, coracoacromial (CA) arch height, coracoid slope, and acromion slope were measured on all bones examined. The coracoclavicular joint was found in 10 (9.8%) of 102 individuals examined. Among them, nine (8.8%) showed bilateral coracoclavicular joints, and a unilateral right joint was noted in one case (1.0%). No significant difference in the incidence of the joint was noted between the right and left side. The incidence of the joint in males, a frequency of 9.8%, was the same as that in females. The joint was not found in individuals under 40 years old. However, the joint was present in 9.5% of those aged 40-59 years, and in 11.4% of those aged 60 years or over. There was no significant difference between various measurements taken from specimens with and without a coracoclavicular joint. These findings suggest that the occurrence of the coracoclavicular joint is related to aging, but not to the size of the scapulae or the slopes and heights of some CA arch elements.

A manual power grip for holding a cylindrical object using a relaxed index finger is described and analysed. In a group of 21 young adult students it provided greater grip strength than the conventional oblique power grip. It allowed a significant increase in the range of adduction-abduction at the wrist. In recent years it appears to have been empirically used by a number of top class racquet players and is the basis of the modern assault rifle grip. A new design of strain gauge dynamometer, in the shape of a cylinder, which permits the testing of a number of grip types and wrist positions is described. Standard grip testing protocol is used with this device which also allows the concomitant use of a goniometer for the assessment of wrist mobility.

During an investigation performed on cadaver forearms in the anatomy department, an unusual insertion of the abductor pollicis longus (APL) muscle together with the extensor pollicis brevis (EPB) muscle was encountered unilaterally in a 40-year-old male cadaver forearm. APL originated from the posterior ulnar surface distal to the anconeus, the adjoining interosseous membrane and middle third of the posterior radial surface. It lay distal to the supinator muscle and close to the EPB, while the EPB arose from the posterior radial surface and from the adjacent interosseous membrane. These muscles were inserted to the palmar side of the base of the first metacarpal bone together. To our knowledge, this variation has not been cited in recent medical literature.

Insight into the molecular basis of inherited photoreceptor cell degeneration has been rapidly evolving during the last decade. The Drosophila Rh1 rhodopsin gene was the first gene shown to cause retinal degeneration when mutated. Many more degeneration-causing mutations in genes encoding rhodopsin and other photoreceptor proteins have been isolated since then in both, Drosophila and humans. To date some 70 mutations of the Drosophila Rh1 gene have been isolated, most of them have been characterized at the molecular level, and more than 60% of them cause retinal degeneration. This review lists the known Rh1 mutations that cause retinal degeneration up to April 1998, gives an overview on the ultrastructural and biochemical correlates of photoreceptor cell degeneration, and suggests a system for the classification of degeneration-causing Rh1 mutations.

The membranous outer segments of vertebrate photoreceptors are supported by cytoskeletons consisting of microtubules and associated proteins, which occur as the ciliary axoneme in rods and cones, and as a separate cytoskeletal system at the incisures of rod outer segments. We performed an immunocytochemical study of the cytoskeleton in photoreceptors isolated from amphibian retinas and found that immunoreactivity to the heavy chain of the motor protein kinesin was closely associated with the microtubules in each of these outer segment cytoskeletal systems. In the outer segments of cones, kinesin heavy chain immunoreactivity was confined to a streak at the axoneme that extended to the outer segment tip. In the outer segments of rods, kinesin heavy chain immunoreactivity was found as both a short streak at the axoneme and a series of long parallel lines that coincided with the microtubules at rod outer segment incisures. Our findings constitute the first report of kinesin in the axoneme of cones and at the incisures of rods. Closely associated with microtubules, kinesin in photoreceptor outer segment axonemes and at rod outer segment incisures can transport materials longitudinally along the microtubules and/or connect these with each other and/or with other components. Because these cytoskeletal systems differ in fundamental ways, kinesin can play different roles in each case, e.g., kinesin at rod outer segment incisures can have structural and functional roles that are unique to rods. These findings may have clinical relevance because similar cytoskeletal systems are expected to occur in the outer segments of human photoreceptors; thus, a disturbance involving kinesin in the cytoskeletal systems at photoreceptor axonemes and/or at rod outer segment incisures could interfere with the normal structure and function of photoreceptors and contribute to human photoreceptor degenerations.

There is increasing evidence that lectins are widely distributed in mammalian tissues, including the nervous tissue. Based on histochemical techniques using neoglycoproteins, different lectin activities specific for different monosaccharides or glycans have been identified (fucose, galactose, mannose, N-acetylglucosamine, N-acetylgalactosamine, N-acetylneuraminic acid and heparin). Most of them showed a cellular specificity and developmental regulation in the central nervous system. Several lectins isolated from the nervous tissue seem to play an essential role during ontogenetic processes, especially as far as cell adhesion and cell recognition mechanisms are concerned (axonal growth and fasciculation, neuron migration, synaptogenesis, myelination). But some of them seem to be involved in signaling events both intracellularly (nuclear lectins) or at the cell surface by autocrine and paracrine mechanisms. This review discusses the structure and the identified functions of these important constituents of the nervous tissue.

Endocardial cushion tissue is formed by an epithelial-mesenchymal transformation of endocardial cells, a process which results from an inductive interaction between the myocardium and endocardium within the atrioventricular (AV) and outflow tract (OT) regions of the heart. We report here that a protein previously found to be required for myocardially induced transformation of endocardial cells in vitro, ES/130, is highly expressed within the AV and OT regions not only by myocardial cells, but also by the endocardium and its mesenchymal progeny. Given these findings and others, we have tested the hypothesis that endocardial cushion tissue secretes factors which autoregulate its transformation to mesenchyme. Endocardial cushion tissue was cultured and its conditioned growth medium was harvested and applied to nontransformed endocardial cells maintained in the absence of the inductive myocardium. This treatment resulted in endocardial cell invasion into three-dimensional collagen gels plus increased expression of proteins associated with endocardial cell transformation in vivo. Whereas endocardial cushion tissue was found to express ES/130 protein in vivo and in vitro, minimal detection of ES/130 in its conditioned growth medium was observed in immunoblots. Attempts to inhibit the mesenchyme-promoting activity of the conditioned medium with ES/130 antisense were unsuccessful. However, strong intracellular ES/130 expression was detected in endocardial cells, and this expression correlated with the ability of endocardial cells to transform. For example, the minority of endocardial cultures that failed to transform in response to conditioned medium treatment also failed to undergo increased expression of ES/130. These observations are interpreted to suggest that (i) endocardial cushion tissue secretes factors that promote its transformation to mesenchyme, and (ii) while endocardial cushion tissue appears to signal through secretion of factors other than or in addition to ES/130, intracellular ES/130 expression nevertheless may be a target endocardial cell response required for endocardial cell transformation.

The morphology of the main vitelline vein and its tributaries which carry the embryotroph from the yolk sac into the rat embryo has been studied by electron microscopy after perfusing the conceptus with a solution of lanthanum nitrate in Karnovsky's fixative. The distribution of the contents of these vessels and the routes taken into and out of the various embryonic compartments have also been investigated. The vitelline vein and its tributaries are lined by a discontinuous endothelial layer, with no basement membrane or mural elements, and it is separated from the exocoelomic cavity by a continuous layer of squamous cells. In addition to the lumina of the vessels of the conceptus, lanthanum nitrate was observed in the mesenchymal space surrounding the yolk sac, the intercellular spaces between the yolk sac endodermal cells but not on their apical surfaces, the intercellular spaces between the cells lining the exocoelomic cavity, the exocoelomic cavity, the mesenchymal space around the umbilical vessels and the intercellular spaces between the ectodermal cells of the embryo. It has been demonstrated that substances enter the exocoelomic cavity mainly through the intercellular spaces of its lining cells via the mesenchymal space around the main vitelline vein and its tributaries. Whilst we were unable to demonstrate gaps in the endothelial lining of the umbilical vessels, it seems to be the likeliest explanation for the presence of lanthanum around its extravascular space. The significance of the distribution of the contents of he vitelline vasculature is discussed.