Balance assessment after altering stimulation of the neurosensory system.

Aim Posture requires fine integrative elaboration, performed by the central nervous system, of neurosensory information originated from the visual, vestibular and spinal circuit. Many perturbing agents can influence this elaboration and then the postural stability. Several studies have evaluated only the effect of a single agent on the postural control. The study analysed the perturbing effect of several external agents on the different sensorial circuits in terms of postural balance loss in orthostatism. Methods The postural stability of 31 patients was evaluated with a static posturography platform in basal conditions and after exposure to an external agent in the following order: stroboscopic light projecting, mechanical rotations on a swivel chair, feet desensitization through ice, administration of an alcoholic drink at intervals which depended on the participant return to basic posturographic values. Tests were performed with open eyes (OE), closed eyes (CE) and reducing plantar perception through the use of a rubber pillow. Results The stroboscopic light altered the postural control. The swivel chair disturbed only with CE. Ice and alcohol increased the oscillation area. The alcohol test had a significant reduction in postural control with OE compared to CE. The rubber cushion increased the oscillation area in all OE tests and with CE in alcohol and ice tests. Conclusion The different agents did not trigger postural control deficits in the same way. A cold environment with psychedelic lights and the use of alcoholic beverages altered significantly the postural stability by influencing simultaneously all perceptions (visual, vestibular and somatosensory feedback).

Gait screening of a population of young, healthy athletes by means of a portable, low-cost device unveils hidden left-right asymmetries in both quadriceps and anterior cruciate ligament forces.

OBJECTIVE: The present study reports the on-field screening of a population of young soccer players in the pursuit of alterations in gait using a portable and low-cost gait analysis system composed of a Wii Balance Board and a webcam. RESULTS: Recordings of motion of the lower extremities along with vertical ground reaction force (GRF) were used to quantify coefficients of symmetry for the overall GRF and the forces exerted by the quadriceps femori and acting on the anterior cruciate ligament (ACL). Data show that, in face of a quite homogeneous symmetry of GRF during left and right stance phases of gait, quadriceps and ACL exert and are subjected to left-right asymmetrical forces that might prelude, especially in young athletes, later alterations of gait.

Arterial and microvascular supply of cerebral hemispheres in the nude mouse revealed using corrosion casting and scanning electron microscopy.

Morphological analyses of cerebral vascularization are not only important for the characterization of the anatomical and physiological relationships between vascular and nervous tissue, but also required to understand structural modifications that occur in many pathological conditions affecting the brain. The aim of this study was to generate a three-dimensional vascular map of the cerebral hemispheres in the nude mouse brain, a widely used animal model for studying tumour biology. We used the corrosion casting (CC) technique to isolate blood vessels from 30 nude mouse brains. All casts were analysed using scanning electron microscopy (SEM), which generated quantitative data regarding vessel length and diameter as well as inter-vascular and inter-branching distances. We identified three different topographical regions: (i) the cortical region, characterized by a superficial wide sheet of vessels giving rise to terminal perforant vessels that penetrate the grey matter; (ii) the inner part of the grey matter, in which dense capillary nets form many flake-like structures extending towards the grey-white matter boundary, where perforant vessels finally change direction and form a well-defined vascular sheet; and (iii) the white matter layer, characterized by a more disorganized vascular architecture. In this study, we demonstrate the accuracy of the CC-SEM method in revealing the 3D-topographical organization of the vascular network of the normal nude mouse brain. These baseline data will serve as a reference for future anatomical investigations of pathological alterations, such as tumour infiltrations, using the nude mouse model.

Early-stage microvascular alterations of a new model of controlled cortical traumatic brain injury: 3D morphological analysis using scanning electron microscopy and corrosion casting.

OBJECT: This study was performed to study the microvascular changes that occur during the first 12 hours after traumatic brain injury (TBI) using the corrosion casting technique. METHODS: The authors performed a qualitative and quantitative morphological study of the changes in cerebral vessels at acute (3 hours) and subacute (12 hours) stages after experimental TBI. They used a model of controlled cortical impact (CCI) injury induced by a recently developed electromagnetic device (impactor), focusing their observations mainly on the microvascular alterations responsible for the formation and maintenance of tissue edema and consequent brain swelling during the first hours after TBI. They used corrosion casting, scanning electron microscopy (SEM), light microscopy, and transmission electron microscopy (TEM) to obtain a morphological qualitative map with both 2D and 3D details. RESULTS: Scanning electron microscopy analysis of vascular casts documented in 3 dimensions the typical injuries occurring after a TBI: subdural, subarachnoid, and intraparenchymal hemorrhages, along with alterations of the morphological characteristics and architecture of both medium-sized and capillary vessels, including ectasia of pial vessels, sphincter constrictions at the origin of the perforating vessels, focal swelling of perforating vessels, widening of intercellular junctions, and some indirect evidence of structural impairment of endothelial cells. All of these vascular alterations were confirmed in 2D analyses using light microscopy and TEM. CONCLUSIONS: The corrosion casting-SEM technique applied to a CCI experimental model proved to be a reliable method for studying the pathophysiology of the vascular alterations occurring at acute and subacute stages after CCI injury. It was also possible to obtain topographical localization of the vascular and cellular events that usually lead to hyperemia, edema, and brain swelling. Moreover, by applying informatic software to anatomical images it was possible to perform quantification and statistical analysis of the observed events.

A new method for the joint visualization of vascular structures and connective tissues: corrosion casting and 1 N NaOH maceration.

Corrosion casting combined with scanning electron microscopy (SEM) has been widely used to study the morphofunctional aspects of microcirculation in many organs. In this study, we present an optimization of the corrosion casting (CC) technique associating it with NaOH 1 N maceration method to obtain a clear visualization of the relationships existing between the microvascular architecture of an organ and its extracellular matrix. Briefly, experiments were performed macerating the tissue previously injected with a low viscosity acrylic resin in 1 N NaOH and then observing it at SEM. In this study, we present an application of this technique to better evaluate the extracellular components of the vascular wall in medium-sized and capillary vessels both in skin and in kidney. The results obtained yielded clear images of the three-dimensional layout of medium-sized and capillary vessels in comparison with the extracellular environment. Furthermore, detailed information was obtained on the three-dimensional layout of fibers constituting the walls of venules, arterioles, and capillaries. In addition, the tubular collagenic structures surrounding the excretory tubules of the kidney and the dermal glands of the skin were depicted and their relationships with their vascular supply described in detail.

Tissue engineering techniques for the treatment of a complex knee injury.

We report and discuss the use of and rationale for tissue engineering techniques in a 40-year-old sportsman who suffered simultaneous anterior cruciate ligament (ACL) rupture, irreparable medial meniscal tear, and chondral lesion of the medial femoral condyle. A 2-step treatment was adopted to address all lesions. The first procedures consisted of ACL reconstruction and collagen meniscus implant (CMI), followed 6 months later by autologous chondrocyte implantation on a collagen membrane (MACI). A CMI biopsy was performed 6 months after implantation. Histologic and ultrastructural analysis documented scaffold invasion by cells and newly synthesized connective tissue. At 2-year follow up, the clinical and functional results were good and magnetic resonance imaging showed integration of the meniscal and cartilage implants. In this patient, each lesion needed to be addressed to achieve an optimal outcome. The primary goal was to restore normal joint biomechanics by performing CMI and ACL reconstruction. MACI was an adequate solution for the management of the large (5 cm(2)) chondral defect.

Whiplash injury and oculomotor dysfunctions: clinical-posturographic correlations.

Oculomotor dysfunctions are hidden causes of invalidity following whiplash injury. Many patients with whiplash injury grade II present oculomotor dysfunctions related to input disturbances of cervical or vestibular afferents. We used static posturography to investigate 40 consecutive patients with whiplash injury grade II and oculomotor dysfunctions. We demonstrated a relation between length and surface of body sway: the surface value (A) was higher than the length value (L) and this led to an open graph of body sway in the statokinesigram. Oculomotor rehabilitation can resolve the impairment of vestibular function but if therapy is delayed or the patient has been wearing an orthopaedic neck collar, more therapeutic sessions are required. In conclusion, without rehabilitation of the oculomotor muscles other therapies are not sufficient to recover the impairment caused by whiplash injury.

The extracellular matrix of the human aortic wall: ultrastructural observations by FEG-SEM and by tapping-mode AFM.

Fragments of human ascending aorta harvested during heart surgery were cryofractured and observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Elastic fibers appear as irregular, undulated laminae of variable size and shape. Their surface shows an evident fibrous texture suggestive of a criss-crossed, delicate filamentous scaffold and is marked by a number of features such as ridges, holes and protruding ribs. At higher magnification, both SEM and AFM show the surface composed of a finely granular material, with a bead size of approximately 20 nm. However, the thickness of the metal coating in one case, and the tip convolution effect on the other, may equally result in an artifactual enlargement of the structures, so that the beads may be significantly smaller. The surfaces created by the fracture always appear smooth and compact and with this technique do not reveal significant detail. The collagen component is mostly represented by small, uniform fibrils gathered in flexuous bundles and following a wavy course not unlike that of the elastic laminae. An orthogonal lattice of small proteoglycans is readily evident even without a specific treatment. Occasionally, the fibrils appear encrusted or engulfed in a grainy matrix reminiscent of the elastic fiber surface. Fluid Tapping-Mode Atomic Force Microscopy simultaneously reveals the surface-bound proteoglycans and the inner architecture of the fibrils, composed of smaller subunits following a spiral course with a winding angle of approximately 17 degrees.

The 3D structure of crimps in the rat Achilles tendon.

The ultrastructure of crimps of the Achilles tendon of rat, excised and processed in a slack condition, was investigated by atomic force microscopy in air, in fluid and by scanning electron microscopy and stereo reconstruction. The tendon was made of distinct fascicles, each comprising a succession of straight segments connected by sharp angles. The length of the segments and the interposed angles varied widely. In particular, the angles ranged from almost zero to over 135 degrees . We did not observe a unique structure for the hinge regions, but rather a variety of gradations of buckling and/or torsion with no evident correlation with other features of tendon. A constant hallmark was the local loss of regular molecular packing, as revealed by the disappearance of the D-banding. Our results do not support recent reports of a helical structure or smooth sinusoidal waves in tendons. Such structures may nonetheless exist in other non-tensile structures whose collagen fibrils exhibit a helical inner architecture and are able to follow a highly convoluted course without buckling or crimping.

A vision-based, 3D reconstruction technique for scanning electron microscopy: direct comparison with atomic force microscopy.

High-resolution, detailed 3D reconstructions of biological specimens obtained from scanning electron microscopy stereo-micrographs and proprietary software were compared with Tapping-Mode AFM datasets of the same fields. The reconstruction software implements several original solutions including a neural adaptive point-matching technique, the ability to build an irregular triangulated mesh rather than a regular orthogonal grid, and the ability to re-map one of the original images exactly onto the reconstructed surface. The technique was applied to human nerve tissue to obtain 1,424 x 968-pixel, texture-mapped datasets, which were subsequently compared against 512 x 512-pixel AFM datasets from the same viewfields. Accounting for the inherent differences of the two techniques, direct comparison revealed an excellent visual match. The correspondence was also quantified by calculating the cross-correlation coefficient between corresponding altimetric profiles in SEM and AFM data, which consistently exceeded a figure of 0.9, with a rate of point mismatch in the order of 0.01%. Research is still underway to improve the robustness of the technique when applied to arbitrary images

Histology and ultrastructure of a tissue-engineered collagen meniscus before and after implantation.

The collagen meniscus implant (CMI) is a tissue-engineering technique designed to stimulate regeneration of meniscus-like tissue in cases of irreparable tears or previous meniscectomy. CMI morphology was investigated before and after implantation by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In a case series biopsy specimens were harvested from four patients who underwent a second arthroscopic look 6 months after placement of the CMI. CMI sections appeared composed of parallel connective laminae of 10-30 microm, connected by smaller bundles (5-10 microm). This connective network formed lacunae with diameters between 40 and 60 microm. At greater magnification, the walls of the lacunae demonstrated tightly packed and randomly distributed collagen fibrils, with diameters ranging from 73 to 439 nm. In the biopsy specimens, the lacunae were filled with connective tissue that contained newly formed vessels and fibroblast-like cells, presenting an abundant rough endoplasmic reticulum and several mitochondria. In the extracellular matrix, the collagen fibrils showed uniform diameters (126 nm +/- 32 nm). The original structure of CMI was still recognizable, and no inflammatory cells were detected within the implant. The morphological findings of this case series demonstrate that CMI provides a three-dimensional scaffold suitable for colonization by precursor cells and vessels and leading to the formation of a fully functional tissue.

The collagenic structure of human digital skin seen by scanning electron microscopy after Ohtani maceration technique.

We performed a morphological scanning electron microscope (SEM) study to describe the fine structure and disposition of collagenous tissue in the human toe. After therapeutic amputation of a human right leg, we applied the Othani maceration technique to the skin of three toes surgically explanted from the foot. We distinguished eight cutaneous regions and focused on some specialized collagenous structures differing in the thickness of the skin. The eight areas investigated were: the dorsal skin, the eponychium, the perionychium, the hyponychium, the region under the visible nail, the nail root, the plantar skin and finally the toe tip. Each of these areas is characterized by a distinctive collagenous surface disposition, with some peculiar features mostly related to dermal papillae. At high magnification, we observed the spatial arrangement of the collagen fibers constituting the top of the dermal papillae that represents the attachment site of the proliferative basal layer of the epidermis. We also noted an impressive density of collagen fibers throughout the thickness of the dermal layer, organized in specialized structures and constituting the skeleton of dermal thermoreceptorial corpuscles or sweat glands. A combination of SEM and Ohtani technique disclosed the three-dimensional architecture of the collagenous matrix of tarsal skin under physiologic conditions, giving a detailed description of the most reactive tissue during pathologic processes.

Structure and ultrastructure of microvessels in the kidney seen by the corrosion casting method.

Scanning electron microscopic observation of corrosion casts is the finest technique to describe spatial patterns of microvessels in many organs, giving a readily interpreted representation of their vascular architecture without interference from surrounding tissues. We focused on the renal cortex of guinea pigs to make an in-depth morphological analysis of structural and ultrastructural details left by the cells on the resin cast. In addition, we made a qualitative description of normal variants usually observed in glomerular disposition, arteriolar morphology or capillary arrangement in the space to shed more light on the relationship between vascular tissue and surrounding cells. The study also disclosed some examples of vascular adaption to physiological and pathological conditions occurring in renal microvessels such as many systems essential to flow regulation, filtration and excretory processes. At lower magnification, all major vessels can be readily distinguished: interlobar, arciform and interlobular arteries and veins, along with a web of peritubular and capsular capillaries. At higher magnification, the glomeruli become visible and the afferent and efferent arteries and the tortuosity the inner vessels can be distinguished. In some of them, the resin, due to the narrowing sizes, suddenly stopped leaving a half-casted glomerulus. This helped to reveal its internal circulation characterized by thin capillaries with a high degree of bi or trifurcation. In addition, we confirmed the close correspondence between cellular ultrastructural detail (pores, corrugations of cellular membrane, perivascular cell branches) and the impressions left on the resin visible only at high magnifications.