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PubMed2000

Quantitative analyses of topography and elasticity of living and fixed astrocytes.

The topography and elasticity of living and fixed astrocytes cultured from the rat cerebra were studied quantitatively by atomic force microscopy (AFM). Ridge-like structures reflecting F-actin beneath the cell membrane were prominent in the contact-mode images of living astrocytes. Many of these ridges became unclear after fixation (2% glutaraldehyde). In addition, the ridge-like structures were invisible in the topography of living cells observed at zero-loading force in the force mapping mode, which is considered to show the real cell surface not pressed down by an AFM tip. The topography of fixed cells observed both in the contact mode and at zero-loading force in the force mapping mode was similar to that of living cells observed at zero-loading force in the force mapping mode, although some deformed areas were detected in the fixed cells. The elasticity map images of living astrocytes showed that the cell membrane above the nucleus was softer (2-3 kPa) than the surroundings, and that the cell membrane above F-actin was stiffer (10-20 kPa) than the surroundings. In the elasticity map images of fixed astrocytes, on the other hand, the elasticity of the cells was found to be relatively uniform (200-700 kPa) irrespective of the inner structures of cells. These results show that images observed by AFM should be carefully examined in consideration of the force introduced to specimens and the elasticity of specimens to find out the real surface topography.

Actins↗
PubMed1999

Angiogenesis inhibitor endostatin is a distinct component of elastic fibers in vessel walls.

Theendothelial cell inhibitor endostatin (22 kDa) is part of the carboxyl-terminal globular domain of collagen XVIII and shows a widespread tissue distribution. Immunohistology of adult mouse tissues demonstrated a preferred localization in many vessel walls and some other basement membrane zones. A strong immunogold staining was observed across elastic fibers in the multiple elastic membranes of aorta and other large arteries. Staining was less strong along sparse elastic fibers of veins and almost none was observed in the walls of arterioles and capillaries. Strong evidence was also obtained for some intracellular and basement membrane associations. Immunogold double staining of elastic fibers showed a close colocalization of endostatin with fibulin-2, fibulin-1, and nidogen-2, but not with perlecan. Reasonable amounts of endostatin could be extracted from aorta and skin by EDTA, followed by detergents, with aorta being the richest source of the inhibitor identified so far. Solubilizations with collagenase and elastase were approximately fivefold less efficient. Immunoblots of aortic extracts detected major endostatin components of 22-25 kDa whereas skin extracts also contained some larger components. Solid-phase assays demonstrated distinct binding of recombinant mouse endostatin to the fibulins and nidogen-2, consistent with their tissue colocalization. Together, the data indicate several different ways for endostatin to be associated with the extracellular matrix, and its release may determine biological activation. This also defines a novel function for some elastic tissues.

Angiogenesis Inhibitors↗
PubMed1993

Levator aponeurosis elastic fiber network.

This light and electron microscopic study demonstrates an elastic fiber network (EFN) for the levator palpebrae superioris muscle complex, which forms an intricate insertion into the upper eyelid. The EFN is examined in the monkey, in a fresh exenteration specimen, and in fresh frozen cadaver specimens from both sexes of different age groups. Multiple elastic insertions of the levator aponeurosis and Muller's muscle attachment with well-organized elastic fibers are demonstrated using special staining techniques and serial microscopic sectioning. Transmission electron microscopy (TEM) confirms the ultrastructure of "mature" elastin fibers in Muller's muscle tendon and their close relationship with the elastin-related fiber, oxytalan. Current thinking concerning the nature of elastic fibers and their possible implications in acquired involutional blepharoptosis is discussed. This microscopic study of the EFN of the upper eyelid focuses attention on the multiple elastic fiber insertions of the levator muscle complex that includes the levator aponeurosis, the conjoined fascia, the lid crease area, and Muller's muscle tendon, which have not been previously described.

Adult↗
PubMed2004

Quantitative evaluation of eyelid elasticity using the cutometer SEM575 and its clinical application in assessing the efficacy of tacrolimus ointment treatment in eyelid atopic dermatitis.

PURPOSE: To study the clinical efficacy of a noninvasive suction device that measures eyelid skin elasticity in the treatment of eyelid atopic dermatitis using tacrolimus (FK-506) ointment. METHODS: Ten patients with eyelid atopic dermatitis treated with tacrolimus ointment and 10 normal volunteers participated in this study. The cutometer SEM575 was used to quantitatively evaluate eyelid skin elasticity. Severity of the eyelid atopic dermatitis was scored, and comparisons were made before and after treatment. RESULTS: Skin elasticity of patients with eyelid atopic dermatitis was significantly lower than that of normal volunteers (31.3 +/- 5.2% vs 40.2 +/- 7.8%, respectively). Skin elasticity of patients with eyelid atopic dermatitis improved significantly to 37.5 +/- 6.3% after treatment with tacrolimus ointment. The total severity score for eyelid atopic dermatitis also improved from 2.77 +/- 1.11 to 1.77 +/- 1.15. CONCLUSION: Measurement of skin elasticity using the cutometer SEM575 is a useful and reliable method for objective and quantitative evaluation of eyelid skin condition in patients with eyelid atopic dermatitis. The efficacy of short-term tacrolimus ointment treatment in patients with eyelid atopic dermatitis was confirmed quantitatively using this apparatus.

Adult↗
PubMed2000

Elasticity of the rod-shaped gram-negative eubacteria.

We report a theoretical calculation of the elasticity of the peptidoglycan network, the only stress-bearing part of rod-shaped Gram-negative eubacteria. The peptidoglycan network consists of elastic peptides and inextensible glycan strands, and it has been proposed that the latter form zigzag filaments along the circumference of the cylindrical bacterial shell. The zigzag geometry of the glycan strands gives rise to nonlinear elastic behavior. The four elastic moduli of the peptidoglycan network depend on its stressed state. For a bacterium under physiological conditions the elasticity is proportional to the bacterial turgor pressure. Our results are in good agreement with recent measurements.

Cell Membrane↗
PubMed2002

Elastic interactions of cells.

Biological cells in soft materials can be modeled as anisotropic force contraction dipoles. The corresponding elastic interaction potentials are long ranged (approximately 1/r3 with distance r) and depend sensitively on elastic constants, geometry, and cellular orientations. On elastic substrates, the elastic interaction is similar to that of electric quadrupoles in two dimensions and for dense systems leads to aggregation with herringbone order on a cellular scale. Free and clamped surfaces of samples of finite size introduce attractive and repulsive corrections, respectively, which vary on the macroscopic scale. Our theory predicts cell reorientation on stretched elastic substrates.

Cell Communication↗
PubMed2003

Elasticity of stiff polymer networks.

We study the elasticity of a two-dimensional random network of rigid rods ("Mikado model"). The essential features incorporated into the model are the anisotropic elasticity of the rods and the random geometry of the network. We show that there are three distinct scaling regimes, characterized by two distinct length scales on the elastic backbone. In addition to a critical rigidity percolation region and a homogeneously elastic regime we find a novel intermediate scaling regime, where the elasticity is dominated by bending deformations.

Biopolymers↗
PubMed2001

Does growth correlate with turgor-induced elastic strain in stems? A re-evaluation of de Vries' classical experiments.

The correlation between growth and turgor-induced elastic expansion was studied in hypocotyls of sunflower (Helianthus annuus) seedlings under various growth conditions. Turgor-induced elastic cell wall strain was greater in hypocotyls of faster growing seedlings, i.e. in etiolated versus light-grown ones. It also was higher in rapidly growing young seedlings as compared with nongrowing mature ones. However, analysis of the spatial distribution of elastic strain and growth demonstrated that their correspondence was only apparent. Profiles of elastic strain declined steadily from the top of the hypocotyls toward the basis, whereas the profiles of relative elemental growth rate along the hypocotyls showed maxima within the growing zones. In contrast to earlier hypotheses, we conclude that turgor-induced elastic cell wall strain and growth do not correlate precisely in growing hypocotyls.

Elasticity↗
PubMed1991

Tissue vitronectin in normal adult human dermis is non-covalently bound to elastic tissue.

Vitronectin is a multifunctional human plasma glycoprotein that is also found in constant association with elastic tissue fibers in normal adults. We have investigated the nature of the association of vitronectin with elastic tissue, and compared it to that of other elastic fiber-associated proteins, namely fibrillin and amyloid P component. Samples of normal human dermis were incubated with a variety of extraction agents, including high molar salt solution, non-ionic detergent (Nonidet P-40), the reducing agents dithiothreitol or 2-mercaptoethanol, and the chaotropic agents sodium dodecyl sulfate or guanidine hydrochloride. Vitronectin purified from serum typically migrates as two bands of 75 and 65 kD. By contrast, immunoblotting studies of residual dermal material after extraction with the various agents revealed only lower molecular weight (58, 50, 42, 35, and 27 kD) anti-vitronectin reactive bands. Although these bands may represent degradation products of vitronectin generated as a result of the extraction procedure, we cannot exclude the possibility that tissue vitronectin is distinct from plasma vitronectin. Anti-vitronectin reactive polypeptides co-migrating with the 58-, 50-, and 42-kD bands were solubilized following extraction with sodium dodecyl sulfate or guanidine hydrochloride, but not with the other extraction agents. Immunofluorescence studies using residual dermal material after extraction with guanidine hydrochloride demonstrated a marked reduction in elastic fiber staining intensity with anti-vitronectin and anti-amyloid P component, but not with anti-fibrillin. Thus the majority, if not all of dermal vitronectin, is, like amyloid P component, non-covalently associated with, and not an integral constituent of, elastic fibers.

Blood Proteins↗
PubMed1989

Tissue amyloid P component in normal human dermis is non-covalently associated with elastic fiber microfibrils.

Tissue amyloid P component (TAP), a protein that crossreacts immunohistochemically with the normal plasma glycoprotein serum amyloid P component (SAP), is invariably associated with elastic fiber microfibrils in adult humans. We have investigated the nature of this association. Aliquots of minced, homogenized dermis, obtained following ethylenediamine tetraacetic acid (EDTA) separation of whole adult human skin, were extracted with different reagents, and the presence or absence of TAP in the pellet and in the supernatant following centrifugation was determined by SDS-PAGE and immunoblotting using anti-SAP antibodies. TAP was extractable from dermis using reagents which disrupt non-covalent bonds, including sodium dodecyl sulfate (SDS) and guanidine hydrochloride. TAP was not extracted by high molarity salt solutions, non-ionic detergents, or the reducing agents dithiothreitol and 2-mercaptoethanol. EDTA solution was similarly unsuccessful at eluting TAP from the dermal preparation, indicating that the association of TAP with elastic fiber microfibrils is not simply the result of Ca++-dependent binding. Collagenase solubilized some TAP, but this does not prove covalent linkage to elastic tissue of part of the TAP, because the apparent Mr of TAP extracted was identical to that of normal SAP subunits. We cannot completely exclude the possibility that a few subunits in each multimeric TAP molecule are covalently attached to the microfibrils. However, our findings that denaturing agents alone extracted most of the TAP from normal human dermis strongly suggest that the great majority of the dermal TAP is non-covalently bound to elastic fiber microfibrils. Thus TAP is not an integral constitutent of elastic fiber microfibrils.

Adult↗
PubMed2004

Fibulin-2 and fibulin-5 alterations in tsk mice associated with disorganized hypodermal elastic fibers and skin tethering.

The Tight skin (Tsk) mouse is an important model of skin fibrosis that occurs in systemic sclerosis. These mice develop skin tethering and thickening associated with expression of a mutant fibrillin-1 gene. We show that Tsk fibrillin-1 leads to marked alterations in elastic fibers of the hypodermis of Tsk animals. In Tsk mice, a prominent elastic fiber layer found normally at the interface between hypodermal muscle and connective tissue was absent from an early age. The lack of elastic fibers at the hypodermal muscle-connective tissue (M-CT) interface was associated with a loss of staining for fibulin-5 in the same region. These mice also formed disorganized elastic fibers throughout hypodermal connective tissue as they aged. The increased elastic fibers in Tsk hypodermal connective tissue was associated with increased fibrillin-1 and fibulin-2 matrices. These results suggest that Tsk fibrillin-1 causes skin tethering by altering matrix protein composition in Tsk hypodermal connective tissues. The closely parallel alterations in elastogenesis associated with increased fibulin-2 in hypodermal connective tissues and decreased fibulin-5 at the hypodermal M-CT interface suggest that these proteins mediate the effect of Tsk-fibrillin-1 on elastogenesis.

Animals↗
PubMed2006

Smooth muscle pattern is more reliable than the presence or absence of an internal elastic lamina in distinguishing an artery from a vein.

BACKGROUND: Major pathology textbooks suggest that the shape of the vessel and the presence or absence of an internal elastic lamina are the best means to distinguish an artery from a vein. Because the shape of the vessel is highly dependent upon the plane of section, the internal elastic lamina is often cited as a more reliable criterion. After evaluating a patient with superficial thrombophlebitis, in whom these conventional criteria had led to a misdiagnosis of polyarteritis nodosa, we sought to determine whether the pattern of smooth muscle in the media is a more sensitive discriminator between an artery and a vein. METHODS: Anatomically identified arteries and veins were harvested from extremity amputation specimens and stored autopsy organ specimens and reviewed by two dermatopathologists who were blinded to the gross pathologist's impression. The biopsies were assessed for the smooth muscle pattern and the presence or absence of an internal elastic lamina. RESULTS: Forty-seven of the 50 cases (94%) were concordant with the pathologist's gross impression using only the smooth muscle pattern to differentiate an artery from a vein. On the basis of the presence or absence of an internal elastic lamina, 41 of 50 cases (82%) were concordant with the prosector's designation of the vessel. LIMITATIONS: Vessels were harvested from a variety of sites, with lower extremity vessels predominating. There may be some regional variability not addressed in this study. CONCLUSION: In this study, the pattern of muscle fibers within the vascular media discriminated between arteries and veins better than assessment of the presence or absence of an internal elastic lamina. Although no single criterion is 100% reliable, assessment of both these criteria may minimize the risk of misinterpreting vessels in the deep dermis and subcutis.

Arteries↗
PubMed1998

Elastic fibers in dermis of juvenile elastoma.

To explore the ultrastructure of elastic fibers in juvenile elastoma, three patients (two without osteopoikilosis and one under examination of bones and joints) were studied by routine electron microscopy. In addition to normal elastic fibers, all the patients also exhibited alterations in elastic fibers. The altered ultrastructures showed lucent, homogenous matrix without peripheral microfibrils. The homogenous matrix were seen in various extensions from the small protrusions of the normal elastic fibers to the complete replacement of the entire fibers. Collagen fibrils occasionally showed twisted figures. Normal shapes of dermal glycosaminoglycans were increased in number. It seems likely that the lucent, homogenous matrix without peripheral microfibrils are the characteristic changes of elastic fibers in juvenile elastoma. The alteration could be nevoid in nature.

Actin Cytoskeleton↗
PubMed2005

Collagen and elastic system in the remodelling process of major types of idiopathic interstitial pneumonias (IIP).

AIMS: Structural remodelling in acute and chronic idiopathic interstitial pneumonia (IIP) has been extensively investigated, but little attention has been directed to the elastic tissue in these situations. The aim of this study was to determine whether elastic deposition accompanies collagen deposition in the four major histological patterns of IIP: diffuse alveolar damage (DAD), organizing pneumonia (OP), non-specific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP). METHODS AND RESULTS: We measured, by image analysis, the content of fibres of the collagenous and elastic systems of the alveolar septum in histological slides of open lung biopsies, using the picrosirius-polarization method and Weigert's resorcin-fuchsin stain, respectively. Five groups were studied: 10 cases of DAD; nine cases of OP; nine cases of NSIP; and 10 cases of UIP. Four normal lungs were used for comparison. The content of collagen fibres was significantly higher in UIP when compared to DAD, NSIP, OP and normal lung. The content of elastic fibres was increased in comparison with normal lungs but this was not significantly different among the histological patterns. CONCLUSION: Acute and chronic IIP cause a similar increase in the collagen and elastic contents of the lungs, representing a process of 'fibroelastosis' rather than an exclusive process of fibrosis. A profibrogenic mechanism is responsible for the unparallelled collagen augmentation observed in UIP subjects, the nature of which is yet to be determined.

Aged↗
PubMed2006

Routine elastic staining assists detection of vascular invasion in colorectal cancer.

AIM: To determine the value of routine staining of colorectal cancer (CRC) specimens with elastic stains. METHODS AND RESULTS: Four hundred and ninety-eight cases of CRC were included. In 208 cases, vascular invasion (VI) was assessed using elastic stains [Elastic van Gieson or Elastin haematoxylin and eosin (H&E)] that were introduced as routine staining in CRC in our hospital. As a control, 290 cases in which VI was assessed solely on H&E staining were included. The site, stage and presence of vascular invasion were determined in both groups. The cost, time and workload resulting from the addition of these stains were also taken into account. The sensitivity of detection of VI in CRC was significantly improved after the introduction of these elastic stains in our routine practice (46.2% compared with 35.5% in the control group; P = 0.014). Particular improvement was noted in Dukes' stage A and B. We also noted that the net benefits gained from the introduction of these special stains outweighed the small extra cost and effort and, in addition, saved time for the reporting pathologists. CONCLUSION: Routine elastic stains are very useful and practical in evaluation of VI status in CRC and we recommend implementing these stains in routine pathological practice to improve patient care.

Adenocarcinoma↗
PubMed2004

Mechanism of transepithelial elimination of elastic fibers in keratoacanthoma.

Transepithelial elimination of elastic fibers is frequently seen in keratoacanthoma. However, the mechanism underlying this elastic fiber transport is not yet fully understood. We investigated the process by comparing the related features of 27 cases of keratoacanthoma, eight cases of squamous cell carcinoma and 11 cases of seborrheic keratosis (control). Microscopically, transepithelial elimination of elastic fibers was specifically observed in keratoacanthomas. Elastic fibers were surrounded by keratoacanthoma cell membrane and were ultrastructurally associated with hemidesmosomes and the basement membrane. Collagen fibrils were also observed within small, membrane-delineated vesicles within cells in the lower layers of the tumor. Also noted was strong expression of matrix metalloproteinase-1, which was detected by immunohistochemical analysis and in situ hybridization. Western blotting showed significantly stronger labeling of matrix metalloproteinase-1 in samples of keratoacanthoma than in normal epidermis. In contrast, squamous cell carcinomas and seborrheic keratosis exhibited none of the aforementioned characteristics. We propose that keratoacanthoma cells entrap, lift and eliminate elastic fibers as they proliferate and keratinize toward the epidermal surface, while simultaneously phagocytosing collagen fibrils. In that regard, matrix metalloproteinase-1 appears to play a key role in the degradation of collagen fibrils.

Adult↗
PubMed1999

Evolution of contractile and elastic properties of rat soleus muscle fibres under unloading conditions.

Rats were submitted to 14 days of hindlimb suspension in order to examine the contractile and elastic properties of the soleus muscles under disuse conditions. The calcium/strontium activation properties, the maximal shortening velocity (V0), as well as the time behaviour of force transients following quick releases and the T1 curves characterizing the active part of the series elastic elements, were determined on single chemically skinned fibres. After the functional measurements, the fibres were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis in order to analyse both the myosin heavy (MHC) and light (MLC) chain isoforms. According to the MHC and MLC composition, two groups of fibres were defined after hindlimb suspension: a group of slow fibres expressing the slow set of both MHC and MLC isoforms, and a group of fast fibres co-expressing the slow and fast MHC and MLC isoforms with a predominant expression of the fast ones. For the first group, the contractile as well as the elastic properties were found to be close to those of control slow soleus fibres. For the second group, both contractile and elastic properties were modified insofar as they became close to those found in a fast muscle such as the extensor digitorum longus. We suggested that between the two populations found in the soleus muscle after hindlimb suspension the modifications in the contractile properties, as well as the alterations in the elastic characteristics, were concomitant to the changes in both MHC and MLC compositions.

Animals↗
PubMed2000

Assessment of elastic properties of the descending thoracic aorta by transesophageal echocardiography with acoustic quantification in patients with a stroke.

Previous studies have described the use of transesophageal echocardiography (TEE) with acoustic quantification (AQ) in assessing aortic elastic properties. We hypothesized that patients with a prior history of stroke (ST) may have a higher risk of atherosclerotic change in great vessels compared to nonstroke subjects (NST) and thus have decreased elastic properties. We assessed the elastic properties of the descending thoracic aorta (DTA) by TEE in ST patients and compared them with data in NST patients. Subjects included 31 with ST without any evidence of emboli originating from the heart (age 51 +/- 10 years, M:F = 20:11) and 25 age-matched NST (M:F = 8:17). Patients with significant valvular heart disease including aortic and mitral regurgitation, left ventricular dysfunction (ejection fraction < 55%), and congenital heart disease were excluded. Compliance (C), distensibility (D), and stiffness index (SI) were measured using AQ and M-mode measurement at a level of the left atrium. We scored atherosclerotic risk factors (ARF) such as a history of diabetes, hypertension, smoking, hypercholesterolemia, and the presence of atheroma of DTA. There was no evidence of atheroma of DTA in NST. There were no significant differences in heart rate and systolic and diastolic blood pressure between ST and NST patients. Fractional area change (FAC) of DTA was significantly lower in ST than in NST patients (3.2 +/- 1.6 vs 5.4 +/- 2.5%, P = 0.000). ST patients had significantly lower C (1.2 +/- 0.4 vs 1.5 +/- 0.7 x 10(-3) cm2 mmHg(-1), P = 0.039), lower D (0.8 +/- 0.3 vs 1.5 +/- 0.8 x 10(-3) mmHg(-1), P = 0.000), and higher SI (10.3 +/- 8.8 vs 5.3 +/- 2.9, P = 0.006) than NST patients. ST patients without atheroma of DTA (n = 21) also had significantly lower C (1.1 +/- 0.4 vs 1.5 +/- 0.7 x 10(-3) cm2 mmHg(-1), P = 0.038) and lower D (3.5 +/- 1.4 vs 4.8 +/- 2.4 x 10(-3) mmHg(-1), P = 0.021) than NST patients. There was a significant positive correlation between SI and the score of ARF (r = 0.51, P = 0.000). The regional elastic properties of DTA measured by TEE with AQ and M-mode method were abnormal in ST. Therefore, TEE with AQ technique may have a possible clinical application for the detection of early atherosclerotic changes such as alteration of elastic properties in morphological normal DTA.

Acoustics↗