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PubMedDate not supplied

[Reconstruction of elastic properties of soft biological tissues from data about it's deformation under dynamic load].

The present work continues theoretical investigations on developing new noninvasive methods for diagnostics of tissue pathologies. These methods are based on tissue elasticity reconstruction using the measured internal displacements occurring due to the deformation of the object under study. Dynamic loading of the object is considered. The robustness of the proposed elasticity reconstruction procedure is demonstrated using numerical modeling of the displacement fields inside the nonhomogeneous object.

Connective Tissue↗
PubMed2005

Lung parenchyma remodeling in a murine model of chronic allergic inflammation.

This study tested the hypotheses that chronic allergic inflammation induces not only bronchial but also lung parenchyma remodeling, and that these histologic changes are associated with concurrent changes in respiratory mechanics. For this purpose, airway and lung parenchyma remodeling were evaluated by quantitative analysis of collagen and elastin, immunohistochemistry (smooth-muscle actin expression, eosinophil, and dendritic cell densities), and electron microscopy. In vivo (airway resistance, viscoelastic pressure, and static elastance) and in vitro (tissue elastance, resistance, and hysteresivity) respiratory mechanics were also analyzed. BALB/c mice were sensitized with ovalbumin and exposed to repeated ovalbumin challenges. A marked eosinophilic infiltration was seen in lung parenchyma and in large and distal airways. Neutrophils, lymphocytes, and dendritic cells also infiltrated the lungs. There was subepithelial fibrosis, myocyte hypertrophy and hyperplasia, elastic fiber fragmentation, and increased numbers of myofibroblasts in airways and lung parenchyma. Collagen fiber content was increased in the alveolar walls. The volume proportion of smooth muscle-specific actin was augmented in distal airways and alveolar duct walls. Airway resistance, viscoelastic pressure, static elastance, and tissue elastance and resistance were significantly increased. In conclusion, prolonged allergen exposure induced remodeling not only of the airway wall but also of the lung parenchyma, leading to in vivo and in vitro mechanical changes.

Actins↗
PubMed1979

A comparative light microscopic evaluation of oxytalan fiber staining with a variety of dye substances.

Staining of oxytalan fibers in marsupial, eutherian and human periodontal ligaments was surveyed with 65 different dyes. Using the criteria of response to preoxidation, distribution, and morphologic appearance, 27 dye preparations in addition to the Gomori aldehyde-fuchsin, Taenzer-Unna orcein, and Weigert resorcin-fuchsin techniques displayed oxytalan fibers. With two exceptions all dyes were cationic and reacted with varying degrees of excellence with different animals. Most dyes produced their best staining results as concentrated solutions in 3% acetic acid, suggesting involvement of oxidatively engendered polyanions predominantly associated with an acid mucopolysaccharide component of the oxytalan fiber. The significance of carboxyl and sulfur-containing groups should not be overlooked in further studies aiming to elucidate oxytalan fiber chemistry and microstructure. This study supported the view that oxytalan fibers belong to the family of elastic tissues and represent a biologically important system within the periodontal ligament.

Animals↗
PubMedDate not supplied

[Morphofunctional study of the cava-hepatic venous transition in humans].

Using mesoscopic techniques, the authors observed that fibrous muscular bundles were distributed in three layers, from the external to the intima, in the cava-hepatic venous transition zone; these bundles start with a helical course, and bend progressively towards their outlet. Regarding the collagen component, two kinds of fibre bundles were observed: 1) as longitudinal strips, two for each vein that join in an arched form close to the outlet; 2) bundles running in the same direction as muscular bundles. The elastic tissue appears as a component of the myoelastic tendons or as independent bundles. The latter follow the direction of the muscular fibres, but show a decreasing amount when they approach the transition zone. At this point, however, the myoelastic tendons grow thicker.

Adolescent↗
PubMed1974

The ultrastructure of the anastomosed vein of experimental arteriovenous fistulae in sheep.

The ultrastructural changes in the anastomosed veins of chronic experimental carotid-jugular arteriovenous fistulae in sheep have been contrasted with the changes in a) the veins of sheep subjected to phlebotomy from the contralateral side and b) the veins of sheep without arteriovenous fistulae. The anastomosed veins exhibited a profound phlebosclerosis which was in marked contrast with the mild degree observable in the contralateral veins of the experimental sheep and with the minimal alterations in control animals. There was progressive and extensive loss of elastic tissue, as well as thickening and proliferation of basement membranes, separation of basement membranes from both the endothelium and smooth muscle cells, and the accumulation of much amorphous material in the interstitium. Collagen was relatively sparse. Some endothelial gaps and denudation were observed and associated with the presence of fibrin and red cells in the intima. Muscle cells exhibited necrosis and degeneration with much cell debris and some extracellular lipid. The results indicate that hemodynamic stress is capable of inducing, in the vessel wall, profound cellular and connective tissue changes.

Animals↗
PubMed1978

Aortic rupture in a patient with elastosis perforans serpiginosa (Lutz-Miescher).

A case of aortic rupture in a 30-year-old women with a rare skin disease, elastosis perforans serpiginosa, is presented. Skin lesions are characterized by marked elastic tissue changes. Multiple large arteries and the distal part of the aorta were thinwalled also with aneurysm-like dilatations. Focal fibroelastosis and degenerative changes were present in the vessel walls. The changes in the aorta made the surgical treatment difficult.

Adult↗
PubMed1989

Water and nutrient supply regimes and the water relations of juvenile leaves of Eucalyptus globulus.

Pressure-volume analysis was used to study effects of irrigation and fertilization on the water relations of newly expanded juvenile leaves of Eucalyptus globulus Labill. seedlings growing in Portugal's Atlantic region. In May, at the beginning of the dry season, fertilization and irrigation treatments had no significant effects on the water relations parameters investigated. In September, at the end of the dry season, leaves from non-irrigated plants had a significantly higher apoplasmic water content and a higher dry weight/turgid weight ratio than leaves of similar physiological age from irrigated trees. The osmotic potential at full turgor and the water potential at the wilting point were lower in non-irrigated than in irrigated plants. Changes in osmotic potential at full turgor were negatively correlated with changes in dry weight/turgid weight ratio, suggesting that reductions in osmotic potential at full turgor were largely the result of decreases in cell size. Fertilization had no detectable effect on these variables or on leaf tissue bulk modulus of elasticity. Tissue elasticity was also unaffected by irrigation. Independently of water and nutrient supplies, leaf elasticity was higher and relative water content at the wilting point lower in leaves sampled in May than in leaves sampled in September. In non-irrigated plants, leaves sampled in September had a lower tissue elasticity and a lower osmotic potential at full turgor than leaves sampled in May, indicating that leaves produced at the end of the dry season generate lower water potentials as turgor is lost than leaves expanded early in the season.

Journal Article↗
PubMed1986

Morphometry of hypoplastic fetal guinea pig lungs following amniotic fluid leak.

Deficient quantity of amniotic fluid causes fetal guinea pig lung hypoplasia. Oligohydramnios that lasts only 5 days in early gestation is sufficient to reduce fetal lung growth significantly. We quantitated lung structural alterations at 50 days gestation (term is 67 days) of fetal guinea pigs whose amniotic fluid was drained on day 45 gestation. The study period spans the late canalicular-early saccular phases of guinea pig lung growth. Compared to littermate controls (n = 4), experimental fetuses (n = 5) have reduced lung:body weight ratio (2.81 +/- 0.16 versus 3.21 +/- 0.20 X 10(-2), p less than 0.01), indicating lung hypoplasia. Lung volume is significantly decreased in the experimental fetuses (1.17 +/- 0.15 versus 1.34 +/- 0.07 ml, p less than 0.05). The proportion of lung containing parenchyma (i.e. developing alveoli and alveolar ducts) is reduced following oligohydramnios (0.83 +/- 0.04 versus 0.90 +/- 0.02, p less than 0.025). The hypoplastic lungs contain fewer saccules (fetal "alveoli") (46 +/- 20 versus 69 +/- 23 X 10(6), p less than 0.1) and the surface area that would be available for gas exchange is decreased (698 +/- 234 versus 974 +/- 80 cm2, p less than 0.05). Lung volume and volume proportion of parenchyma are reduced in the experimental lung and therefore diminished parenchymal elastic tissue is anticipated. However, the total length of parenchymal elastic tissue in the experimental lungs is decreased to a surprising degree and is little more than half the length in control lungs (504 +/- 222 versus 974 +/- 70 m, p less than 0.0025). Such marked reduction in total length suggests that factors other than smaller lung size have contributed to the decrease of elastic tissue in the experimental group. In fact, elastic tissue length per unit volume is significantly reduced (509 +/- 189 versus 809 +/- 115 m/cm3, p less than 0.025) indicating an absolute decrease in parenchymal elastic tissue in the hypoplastic lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniotic Fluid↗
PubMed1999

Internal deformation of a uniform elastic solid by acoustic radiation force.

Tissue elasticity estimation is a growing area of ultrasound research. One proposed approach would apply acoustic radiation force to displace tissue and use ultrasonic motion tracking techniques to measure the resultant displacement. Such a technique might allow noninvasive imaging of tissue elastic properties. The potential of this method will be limited by the magnitude of displacements which can be generated at reasonable acoustic intensity levels. This paper presents methods for estimating the internal displacements induced in an elastic solid by acoustic radiation force. These methods predict displacements on the order of 400 microns in the human vitreous body, 0.008 micron in human breast, and 0.020 micron in human liver at an acoustic intensity of 1.0 W/cm2 (in water) and an operating frequency of 10 MHz. While the displacement generated in the vitreous should be readily detectable using ultrasonic methods, the displacements generated in the breast and liver will be much more difficult to detect. Methods are also developed for predicting the time dependent temperature increases associated with attenuated acoustic fields in the absence of perfusion. These results indicate promise for radiation force imaging in the vitreous, but potential difficulties in applying these techniques in other parts of the body.

Elastic Tissue↗
PubMed1989

The tissue distribution of microfibrils reacting with a monospecific antibody to MAGP, the major glycoprotein antigen of elastin-associated microfibrils.

Elastic tissue, when viewed in the electron microscope, consists of an amorphous component that is immunoreactive with anti-tropoelastin (TE) antibodies and microfibrils, that react with monospecific antibodies against a 31 kDa microfibrillar glycoprotein constituent, called MAGP. A detailed study of the tissue distribution of microfibrils and of the two elastic tissue antibodies has been carried out, using single and double-labeled immunogold techniques in high resolution electron microscopy. Microfibrils similar in appearance to those associated with elastic tissue and immunoreactive with the anti-MAGP antibody, have been demonstrated in many tissues in the absence of amorphous elastic tissue. In the majority of these tissues, specific anti-TE antibody localization was demonstrated in the immediate vicinity of the microfibrils, or alternatively, the microfibrils were shown to be in direct continuity with microfibrils of similar morphology, which were associated with material immunoreactive with anti-TE antibody. The diameter of these microfibrils varied between 8 nm and 16 nm. They were unbranched structures of indefinite length, with a tubular profile on cross section and periodic staining in longitudinal section. In some tissues, notably in the ciliary zonule and in the mesangial region of the renal glomerulus, microfibrils of similar morphology were demonstrated which were immunoreactive with anti-MAGP antibody, but which were unrelated to amorphous elastic tissue and with which anti-TE antibody localization could not be demonstrated. The evidence available supports the conclusion that all these microfibrils are members of a single class of structures, which are widely distributed in the tissues and which are secreted by a range of cell types. Attention is directed to the close relationship between these microfibrils and the basement membrane of the glomerulus, of uterine smooth muscle, of the basal cells of the epidermis and of the reticulum cells of the spleen.

Animals↗
PubMedDate not supplied

Effects of cold preservation on the lung mechanical properties in rats.

In lung transplantation, cold preservation is an important process. However, the mechanical changes in the airway and tissue during cold preservation, especially before reperfusion, are unknown. To test the hypothesis that the mechanical changes in the airway and lung parenchyma start during cold preservation, we investigated the mechanical properties of the rat lung as a whole organ and in excised lung strips. In the 0 h group, the lungs were not preserved. In the 9 and 24 h group, the lungs were preserved for 9 and 24 h at 4 degrees C. After preservation, we evaluated the static compliance (Csta) of the whole lung as obtained from the pressure volume curves (n=5 in each group). Also, we measured the input impedance taken by a computer-controlled small-animal ventilator (n=9 in each group). All data were analyzed using a homogeneous linear model, which includes airway resistance (Raw), tissue elastance (H), and tissue resistance (G). Hysteresivity (eta) was calculated as G/H. Moreover, the tissue elasticity (Eqs) obtained from the quasi-static stress-strain curves was compared. There was no significant difference in Csta among the three groups. Raw was significantly lower in the 24 h group than in the 0 h group (p<0.01). Eqs was significantly higher in the preserved groups than in the 0 h group (p<0.01). These results demonstrated that the changes in the three mechanical properties of the airway and the tissue started within 9 h of preservation.

Animals↗
PubMed2006

Influence of inflated lung pressure on lung mechanical properties during cold storage in rats.

The degree of lung inflation pressure during cold storage has a deep connection with lung functions after reperfusion. However, the change of the lung mechanical properties during cold storage at the different lung inflation pressure is unknown. We investigated the change of the mechanical properties both at the organ and the tissue level under different inflated lung pressure soon after the cold storage. In group I, the lungs were not preserved. In group II, the lungs were preserved in deflated condition. In groups III and IV, the lungs were inflated with room air at pressures of 14 and 25 cm H2O. After 24-hour storage, the input impedance (Z) was measured by a computer-controlled small animal ventilator (n = 8 each group). All data were analyzed using a homogeneous linear model, which includes airway resistance (R(aw)), tissue elastance (H), and tissue damping (G). Hysteresivity (eta) was calculated as G/H. After Z measurement, the tissue elasticity (Eqs) obtained from the quasi-static stress-strain curve was compared. We also analyzed the biochemical changes of surfactant in bronchoalveolar lavage (BAL) fluid. R(aw )was significantly lower in groups III and IV than in group I (p < 0.01). Hysteresivity (eta) was significantly lower in group IV than in groups I and III (p < 0.05). Eqs was significantly higher in groups III and IV than in groups I and II (p < 0.01). The total protein level in the BAL fluid of the preserved groups was significantly higher compared with group I (p < 0.01). We conclude that hyperinflated storage would deteriorate lung tissue mechanical properties.

Acclimatization↗
PubMed1992

Middermal elastolysis in an elderly man with evidence of elastic fiber phagocytosis.

BACKGROUND: Middermal elastolysis is a clinically and histologically distinct entity. This idiopathic loss of dermal elastic fibers has mostly been reported in younger adults. To our knowledge, the present case, which has been followed up for 4 years, is the first to occur in an elderly man. OBSERVATIONS: Two years after the onset of progressive wrinkling of the upper aspect of the thorax, the patient underwent a biopsy. Histologic examination of the specimens confirmed previous findings of middermal elastolysis. Examination of extracutaneous elastic tissue showed normal findings. Electron microscopy demonstrated elastic fibers embraced by macrophages, which is suggestive of elastic fiber phagocytosis. For the following 4 years, the patient has remained in stable clinical condition. CONCLUSIONS: Middermal elastolysis is probably more common than has been assumed so far. It does not affect nondermal elastic tissue. After progressive loss of dermal elasticity in a circumscribed area, a benign course follows, with a stable condition over several years. Electron microscopic findings indicate that elastic fiber phagocytosis is operative in the disappearance of the middermal elastic tissue.

Aged↗
PubMed1980

Elastosis in benign and malignant salivary gland tumors. A histochemical and ultrastructural study.

One hundred sixteen cases of various types of salivary gland tumors were examined for the presence of elastic tissue. Almost all the pleomorphic adenomas (97%) and all the malignant pleomorphic adenomas contained elastic tissue in varying amounts. A high percentage (82%) of adenoid cystic carcinomas also contained elastic tissue but the overall quantity was significantly less than in pleomorphic adenomas. All other salivary gland tumors studied, i.e. adenolymphomas, oxyphilic adenomas, mucoepidermoid tumor, and various variants of monomorphic adenomas, were devoid of significant elastic tissue. At the ultrastructural level, the elastic fibers were mainly seen close to neoplastic myoepithelial-like cells, and all stages of elastogenesis were present, ranging from young elastic fibers with a high microfibrilelastin ratio, usually associated with basal-membrane-like material, to mature fibers consisting mainly of an amorphous electron lucent central elastin component. It is postulated that elastic tissue in the salivary gland tumors is produced by the myoepithelial-like tumor cells rather than by tumor stromal induction as has been described in some types of breast carcinomas.

Adenolymphoma↗
PubMed1993

Abnormalities of connective tissue components in lesional and non-lesional tissue of patients with pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is a disorder of connective tissue in which abnormalities of elastic tissue and collagen are found. The purpose of this study was to examine the ultrastructure and distribution of connective tissue components in lesional and non-lesional skin of patients by means of indirect immunofluorescence, electron microscopy and indirect immunoelectron microscopy. Prominent abnormalities of elastic tissue were seen on electron microscopy and confirmed by immunoelectron microscopy. Abnormal elastic fibers containing electron-dense bodies and holes were seen even in non-lesional skin. In addition, the normal pattern of collagen bundles was disrupted in lesional skin, but not in non-lesional skin of patients with PXE. The majority of individual collagen fibrils appeared normal by electron microscopy. The distribution of type IV collagen and laminin was normal in small blood vessels. Finally, abnormalities in the distribution of fibronectin were seen. The finding of atypical elastic fibers in non-lesional skin supports an early role for elastic tissue components in the pathogenesis of PXE. Interactions between elastin, collagen and other matrix substances may explain some of the abnormalities seen.

Collagen↗
PubMed1991

Elastic-like tissue, a new component of the renal glomerular capillary wall in a cartilaginous fish.

Elastic-like tissue composed of tubular microfibrils continuous with, and disappearing into, amorphous material is present in the connective tissue space of the glomerular capillary wall of the river ray (freshwater elasmobranch) kidney. The amorphous material is stained by tannic acid but not by uranyl acetate. Structures with similar morphology and staining characteristics are also found in the subendothelial connective tissue layer of renal arteries in this species. Comparative ultrastructural observations of kidneys from marine rays show elastic-like tissue in the arterial wall but not in the glomerular vessels.

Animals↗
PubMed2005

Developmental changes in airway and tissue mechanics in mice.

Most studies using mice to model human lung diseases are carried out in adults, although there is emerging interest in the effects of allergen, bacterial, and viral exposure early in life. This study aims to characterize lung function in BALB/c mice from infancy (2 wk) through to adulthood (8 wk). The low-frequency forced oscillation technique was used to obtain impedance data, partitioned into components representing airway resistance, tissue damping, tissue elastance, and hysteresivity (tissue damping/tissue elastance). Measurements were made at end-expiratory pause (transrespiratory system pressure = 2 cmH2O) and during relaxed slow expiration from 20 to 0 cmH2O. Airway resistance decreased with age from 0.63 cmH2O x ml(-1) x s at 2 wk to 0.24 cmH2O x ml(-1) x s at 8 wk (P < 0.001). Both tissue damping and tissue elastance decreased with age (P < 0.001) from 2 to 5 wk, then plateaued through to 8 wk (P < 0.001). This pattern was seen both in measurements taken at end-expiratory pause and during expiration. There were no age-related changes seen in hysteresivity when measured at end-expiratory pause, but the pattern of volume dependence did differ with the age of the mice. These changes in respiratory mechanics parallel the reported structural changes of the murine lung from the postnatal period into adulthood.

Adaptation, Physiological↗