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At least 361 records · Page 20Linked to original sources
PubMed1992

A re-evaluation of the distribution of the elastic meshwork within the periodontal ligament of the mouse.

The elastic properties of the periodontal ligament have been attributed, in part, to oxytalan fibers, as no other types of elastic fibers are described there. It has been difficult to study the periodontal elastic meshwork by standard microscopic techniques because it is partially obscured by the adjacent periodontal ligament collagen fibers. Our study employed methods which either completely or partially removed mandibular molar periodontal ligament collagen fibers, exposing a previously undescribed periodontal elastic meshwork. The periodontal elastic meshwork was composed of many elastin lamellae containing both peripheral microfibrils of regular arrangement and central microfibrils of irregular arrangement, which could only be demonstrated in oxidized tissues. Peripheral, regularly arranged bundles of microfibrils resembled oxytalan fibers, which were often adherent to the border of the elastin lamella. Elastin lamellae containing irregular microfibrils resembled elaunin fibers. These fibers probably enclosed either blood vessels, nerves or collagen fiber bundles. Peripheral microfibrils attached elaunin to cementum, alveolar bone, blood vessels, and principal periodontal collagen fibers. Thus, the periodontal elastic meshwork is composed of both oxytalan and elaunin fibers. Microfibrils attach elaunin fibers to the adjacent non-elastic tissue and also form bundles which traverse the periodontal ligament space and are probably the oxytalan fibers demonstrable by light microscopic techniques. This meshwork of oxytalan and elaunin fibers probably contributes to tooth support and maintenance of periodontal homeostasis by dissipating chewing forces and maintaining patency of periodontal blood vessels.

Animals↗
PubMed1976

Esophageal elastance in awake and anesthetized recumbent dogs.

Esophageal elastance was measured in trained dogs placed in the prone, supine, and left lateral postures before and during sodium thiopental anesthesia. Esophageal elastance was measured from static pressure-volume curves and during spontaneous breathing at functional residual capacity. There was a significant decrease in esophageal elastance, estimated from the pressure-volume curves, during anesthesia in both prone and lateral positions but not in the supine posture. Changes in vagal tone produced by stimulation of the vagal nerves did not alter esophageal elastance. Therefore, underlying mechanisms for these changes in esophageal elastance are not fully understood. There was an increase in esophageal elastance when lung volumes increased from 55 to 80% total lung capacity. However, we did not find a significant change in esophageal elastance between awake and anesthetized conditions or between positions during spontaneous breathing at functional residual capacity.

Anesthesia↗
PubMed2006

Two-photon microscopy of vital murine elastic and muscular arteries. Combined structural and functional imaging with subcellular resolution.

Understanding vascular pathologies requires insight in the structure and function, and, hence, an imaging technique combining subcellular resolution, large penetration depth, and optical sectioning. We evaluated the applicability of two-photon laser-scanning microscopy (TPLSM) in large elastic and small muscular arteries under physiological conditions. Elastic (carotid) and muscular (uterine, mesenteric) arteries of C57BL/6 mice were mounted in a perfusion chamber. TPLSM was used to assess the viability of arteries and to visualize the structural components elastin, collagen, nuclei, and endothelial glycocalyx (EG). Functionality was determined using diameter changes in response to noradrenaline and acetylcholine. Viability and functionality were maintained up to 4 h, enabling the assessment of structure-function relationships. Structural vessel wall components differed between elastic and muscular arteries: size (1.3 vs. 2.1 microm) and density (0.045 vs. 0.57 microm(-2)) of internal elastic lamina fenestrae, smooth muscle cell density (3.50 vs. 1.53 microm(-3)), number of elastic laminae (3 vs. 2), and adventitial collagen structure (tortuous vs. straight). EG in elastic arteries was 4.5 microm thick, covering 66% of the endothelial surface. TPLSM enables visualization and quantification of subcellular structures in vital and functional elastic and muscular murine arteries, allowing unraveling of structure-function relationships in healthy and diseased arteries.

Acetylcholine↗
PubMed1994

Computerized measurement of penile elastic fibres in potent and impotent men.

Intracavernous elastic fibres may play a role in human erectile tissue compliance and elasticity. Using computerized image analysis we have measured objectively the percentage of elastic fibres in corpus cavernosum tissues in both potent and impotent men. Twenty-two penile biopsies were performed in 5 potent and 17 impotent patients due to vascular disease. The mean percentage of elastic fibres was 9% in normal patients. In 12 patients with venous leakage a significant decrease in the amount of elastic fibres of 5.1% was observed and in 5 patients with arterial disease it was 4.3%. No correlation between the reduction of the elastic fibre quantification and age was observed. Change in elastic fibre content may alter the relaxation properties of cavernosal tissue and play a role in the development of erectile dysfunction.

Adult↗
PubMed1980

The effects of airway anesthesia on detection of added inspiratory elastic loads.

We studied the effects of airway anesthesia on the ability to detect added inspiratory elastic loads in 5 healthy conscious human subjects. The ability to detect inspiratory elastic loads (range, 0.933 to 2.125 cmH2O/l) was determined by repeated single-breath presentation of different elastic loads by connecting the inspiratory side of a mouthpiece to rigid boxes of adjustable volume. In addition, measurements of total respiratory elastance, body plethysmography and pattern of ventilation were made. In each subject, the study was repeated after a local application of 4% lidocaine solution to the upper airways and, on a separate occasion, to both upper and lower airways. The mean values for respiratory elastance, the threshold elastic load, and the Weber fraction during the control periods were not statistically different from the mean values after upper airway anesthesia or combined upper and lower airway anesthesia. These results suggest that the site of elastic load detection in normal subjects does not reside in the upper or lower airways.

Adult↗
PubMed1990

Distribution of elastic cartilage in the arytenoids and its physiologic significance.

An investigation of the distribution of the elastic cartilage in the arytenoids was performed on excised human adult and newborn larynges. The distribution of elastic cartilage in the arytenoids was investigated histologically in two serial sections: horizontal and coronal. The behavior of the elastic cartilage portion of the arytenoids was investigated histologically under the conditions of adduction and abduction. The results are summarized as follows. 1) Elastic cartilage is found not only at the tip of the vocal process but at the superior portion of the arytenoid cartilage from the vocal process to the apex. 2) This phenomenon is observed at birth. 3) The vocal process bends at the elastic cartilage portion during adduction and abduction. The sides of the arytenoids come into contact mainly at the elastic cartilage portion. 4) Elastic cartilage appears to play an important role in the physiologic functioning of the arytenoid.

Adult↗
PubMed2000

Reconstructive ultrasound elasticity imaging for renal transplant diagnosis: kidney ex vivo results.

It may be possible to diagnose and monitor scarring, inflammation and edema in transplant kidney using reconstructive ultrasound elasticity imaging. Kidney elasticity is expected to change dramatically with scar, and to a lesser degree, with acute inflammation and edema. The hypothesis that changes in kidney elasticity can be imaged using a clinical ultrasound scanner was experimentally tested with an ex vivo canine kidney model, and results on a single pair of kidneys are reported in this paper. A cross-linking agent affected kidney elasticity both globally and locally. Elasticity changes were monitored with accurate estimates of internal displacement and strain followed by Young's modulus reconstruction. The results of this study strongly suggest that ultrasound elasticity imaging can detect elasticity changes in complex structures such as the kidney. Moreover, it has the potential to become an important clinical tool for renal transplant diagnosis.

Animals↗
PubMed1998

External work and potential for elastic storage at the limb joints of running dogs.

The storage and recovery of elastic strain energy in muscles and tendons increases the economy of locomotion in running vertebrates. In this investigation, we compared the negative and positive external work produced at individual limb joints of running dogs to evaluate which muscle-tendon systems contribute to elastic storage and to determine the extent to which the external work of locomotion is produced by muscles that shorten actively rather than by muscles that function as springs. We found that the negative and positive external work of the extensor muscles is not allocated equally among the different joints and limbs. During both trotting and galloping, the vast majority of the negative work was produced by the two distal joints, the wrist and ankle. The forelimb produced most of the negative work in both the trot and the gallop. The hindlimb produced most of the positive work during galloping, but not during trotting. With regards to elastic storage, our results indicate that the forelimb of dogs displays a greater potential for storage and recovery of elastic energy than does the hindlimb. Elastic storage appears to be more important during trotting than during galloping, and elastic storage appears to be more pronounced in the extensor muscles of the distal joints than in the extensor muscles of the proximal joints. Furthermore, our analysis indicates that a significant portion of the external work of locomotion, 26 % during trotting and 56 % during galloping, is produced by actively shortening muscles. We conclude that, although elastic storage of energy is extremely important to the economy of running gaits, actively shortening muscles do make an important contribution to the work of locomotion.

Animals↗
PubMed2005

Transdermal delivery of an analgesic agent using elastic liposomes: preparation, characterization and performance evaluation.

The aim of the present study was to prepare and characterize novel vesicular carrier elastic liposomes, of most commonly used non-steroidal anti-inflammatory agent diclofenac for its sustained and targeted delivery. Elastic liposomes of diclofenac were prepared and characterized in vitro and in vivo. The effect of different formulation variables like type of surfactant, concentration of surfactant and dose of drug on transdermal flux, amount of drug deposited into the skin, muscle and plasma concentration was investigated. The biological activity of optimized formulation was evaluated using carrageenan induced rat paw edema model and results were compared with commercial hydrogel formulation. The elastic liposomal formulations achieved muscle drug concentration between 2.2+/-0.14 to 5.3+/-0.22 microg/g at 12 hr. The same dose of commercial hydrogel formulation produced drug levels between 0.41+/-0.07 to 1.1+/-0.09 microg/g in the muscle. Plasma concentration study showed regiospecificity of elastic liposomal formulation. The results of in vivo study revealed that incorporation of diclofenac in elastic liposomes increased its biological activity two fold as compared to commercial hydrogel formulation. The results of the present study demonstrated greater effectiveness of dermaly applied diclofenac elastic liposomal formulation in comparison to conventional delivery system. The optimized elastic liposomal formulation offers a promising means for the non-invasive treatment of local pain and inflammation by topical application.

Administration, Cutaneous↗
PubMed1994

Experimental analysis of brain surface elastance in cats.

Brain surface elastance, defined as the pressure needed to compress the cortex 3 mm, was measured using the ophthalmodynamometer in six cats using three burr holes (frontal, parietal, and occipital) on each side. An intracranial mass was then used to compress the right side for 3 hours, and cardiac arrest was induced after the mass was removed. Elastance was measured four times: before insertion of the mass, 10 and 70 minutes after removal of the mass, and 60 minutes after cardiac arrest. The results showed that: brain surface elastance does not change between sides, but varies among regions with the parietal region having the highest elastance; elastance increases after compression by an intracranial mass, but not after cardiac arrest; and stiff brain tends to restore poorly. Elastance is apparently increased by the formation of edema. Measuring brain elastance may be useful in predicting brain restoration subsequent to removal of mass lesions.

Animals↗
PubMed2000

Fiber arrangement of the rat splenic capsule with special reference to elastic fibers.

The fiber arrangement of the rat splenic capsule was examined under scanning electron microscope (SEM) after selective removal by chemical maceration of capsule components, in conjunction with examination of thin sections using a transmission electron microscope (TEM). TEM findings were compared to those of the guinea-pig, mouse and dog. Serosal cells of the rat splenic capsule showed labyrinthic channels that consisted of expanded intercellular spaces and tunnel-like spaces or slits in the basal cytoplasm. The channels contained fascicles of collagenous fibrils, forming a loose net on an underlying elastic lamina of densely aggregated elastic fibers. The fibrous tunica was an intermingled layer of elastic and collagenous fibers and sparse interstitial cells. The fibrous components were arranged more densely in the external layer than in the internal layer of the capsule. The elastic lamina comprised the outermost layer of the fibrous tunica in the intertrabecular region, but was situated deep in the trabecular region. Outward branches of the lamina in the trabecular region were arranged in a spiral. Intrachannel fibrillar fascicles were continuous, via fenestrations in the elastic lamina, with thick fascicles of collagenous fibers. The elastic lamina may play a role in effective contraction of whole spleen. In the guinea-pig, mouse and dog, elastic fibers were fragmented and not arranged in laminae. Typical smooth muscle cells were abundant in the dog. The channel spaces in the serosal tunica are discussed from the viewpoint of extravascular lymphatic flow for circulation of the peritoneal serous fluid.

Animals↗
PubMed1977

Elasticity of the spinal cord dura in the dog.

The elasticity of the spinal cord dura in the dog has been investigated histologically, in situ, and by measurement. The dura was composed of collagenous and elastic connective tissue fibers. The collagenous fibers were arranged in longitudinal bundles, straight when stretched and wavy when unstretched, with a delicate network of fine elastic fibers coursing in all directions. Transecting the cord and dura at T-5 caused a separation of 25 to 30 mm of the dura and a 15- to 20-mm gap in the cord. By means of an appropriate sequence of transections of nerve roots and denticulate ligaments within the dura, and transections of the dural sheaths and nerves outside the dura, the strain on the dura was found to be imposed by the attachments of the dural nerve sheaths from T-6 to S-7. The filum terminale was not appreciably strained. By adding weights to a suspended dura, two components of elasticity were found. For loads of 0 to 50 gm, the incremental displacements in the length were large. The elastic modulus was about 4 X 10(6) dynes/sq cm, which was comparable to that of elastic fibers. For loads of 50 to 150 gm the displacements in length were small. The elastic modulus was about 5 X 10(8) dynes/sq cm, which was comparable to that of collagenous fibers.

Animals↗
PubMed1997

Elastance of the pleural space: a predictor for the outcome of pleurodesis in patients with malignant pleural effusion.

BACKGROUND: In patients who have malignant pleural effusion, it is difficult to diagnose trapped lung before thoracoscopy, thoracostomy, and drainage of the effusion. Predicting the outcome of pleurodesis in patients who have malignant pleural effusion without trapped lung is also difficult. OBJECTIVE: To investigate the factors that may be useful in diagnosing trapped lung and predicting the outcome of pleurodesis. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: 65 patients with symptomatic malignant pleural effusion. INTERVENTION: A chest tube was inserted for drainage of the effusion, and pleurodesis was done using bleomycin as the sclerosant. MEASUREMENTS: The pH and glucose levels of the effusion and the elastance of the pleural space (defined as the decline in pleural fluid pressure in cm H2O after removal of 500 mL of effusion) were measured. The outcome of pleurodesis was evaluated 1 month after the chest tube was removed. RESULTS: Patients with an elastance of 19 cm H2O or more had a higher incidence of trapped lung (11 of 14 patients) than did those with an elastance less than 19 cm H2O (3 of 51 patients) (P < 0.001). None of the 14 patients with an elastance of 19 cm H2O or more and none of the 14 patients with a trapped lung had successful pleurodesis. Forty-two of 43 patients with an elastance less than 19 cm H2O who did not have a trapped lung had successful pleurodesis. Elastance seemed to be the best predictor for trapped lung and outcome of pleurodesis, although outcome was also correlated with pH and glucose levels of the effusion. Low-dose bleomycin (30 mg) is as effective as the usual dose of bleomycin (60 mg) for pleurodesis. CONCLUSION: In patients with symptomatic malignant pleural effusion, measurement of the elastance of the pleural space is a simple and effective method for the diagnosis of trapped lung and prediction of the outcome of chemical pleurodesis with bleomycin.

Adult↗
PubMedDate not supplied

Elastic recoil following percutaneous transluminal coronary angioplasty and Palmaz-Schatz stent implantation.

The post-procedural elastic recoil in 133 lesions treated with the Palmaz-Schatz stent was compared to 133 matched lesions treated with balloon angioplasty to determine the role of prevention of elastic recoil in the creation of a larger initial luminal diameter. Elastic recoil was defined as the difference between the maximal diameter of the inflated balloon and the minimal luminal diameter of the dilated segment immediately after the procedure and was evaluated by quantitative coronary angiography. Overdilatation was defined as a dilatation induced by a balloon with a maximal diameter larger than the pre-procedure reference diameter. The percent diameter stenosis was reduced from 73% to 31% in the balloon angioplasty group and from 72% to -4% in the stent group (31% vs. -4%, p < 0.01). Elastic recoil was significantly larger in the balloon angioplasty group than in the stent group (0.94 +/- 0.29 mm vs. 0.09 +/- 0.09 mm, p < 0.01). Overdilatation and lesion morphology had no significant effects on elastic recoil in the stent group. In the balloon angioplasty group, overdilatation, noncalcified lesions and eccentric lesions were associated with increased elastic recoil. These results indicated that the larger post-procedural luminal diameter associated with the Palmaz-Schatz stent was primarily the result of prevention of elastic recoil, which was not influenced by the degree of overdilatation or lesion morphology.

Angioplasty, Balloon, Coronary↗
PubMed2002

[Comparative analysis of elastic materials for lining of removable dental prosthesis in vitro].

This work has dealt with the in vitro physicochemical, elastic, and microbiological properties of polymer lining materials used in dental prosthetics. Representatives of two soft polymer groups were analyzed: Vertex Soft NF, a plastified acrylic polymer, and Molloplast B, a silicon elastomer. Vertex Rapid Simplified and Triplex--two acrylic polymers routinely used at the Department of Prosthetic Dentistry were chosen as representatives of rigid acrylic material. The laminar plates of the denture are lined with elastic material to reduce wear discomfort and eliminate symptoms associated with compression of the oral mucosa by the denture. Wear-dependent deterioration in physicochemical, elastic, and microbiological properties presents as prosthetic stomatopathies due to the combined action of mechanical lesions, fungal growth, and toxicity of components of the denture, necessitating replacement of the denture. Samples used in this study were prepared at the Department of Dental Prosthetics, Pomeranian Academy of Medicine. The process of polymerization was carried out strictly as recommended by the manufacturers. The in vitro analyses were done at the Polymer Institute, Technical University of Szczecin, and the Department of Microbiology and Immunology, Pomeranian Academy of Medicine. A special system was used to reproduce conditions in the oral cavity and study their effects on the elastic liners. Samples were placed in the chamber for varying periods, depending on the type of test and material. Thermodynamic analysis was done to confirm proper polymerization and hardening. Time-dependent loss of contact between the elastic liner and rigid denture under tangential (shear) and normal (tear) stress applied to the liner-denture interface was examined. Resistance was studied using INSTRON model 4206-006 universal testing machine. Compressive changes in elastic properties of the soft materials were examined by calculating Young's modulus. Changes in viscoelastic properties of the materials depending on temperature and frequency were followed using dynamic mechanical thermal analysis (DMTA). A precision microbalance from Sartorius (+/- 0.00001 g) was used to measure time-dependent changes in weight and sorption of water. Adhesion of Candida albicans to the rigid and soft acrylic materials was determined after incubation for 3, 6 or 24 h at 37 degrees C. The study has shown that adhesive strength is much greater for acryl-acryl than acryl-silicon interface. Elastic properties of Molloplast B are very stable and superior to those of Vertex Soft NF. Time-dependent sorption of water and changes in weight have confirmed the stable nature of Molloplast B. Adhesion of Candida albicans to Vertex Soft NF was less noticeable.

Bacterial Adhesion↗
PubMed1992

[The angiographic evaluation of elastic recoil after coronary angioplasty].

Coronary angioplasty is an effective recanalization technique, but is plagued by a high restenosis rate. One of the major effects of balloon dilatation is the stretching of the vessel wall and the subsequent elastic recoil. Although a well known phenomenon, few data have been published on the evaluation of elastic recoil after coronary angioplasty. The purpose of this study was to quantify the acute and short-term elastic recoil after coronary dilatation. Thirty-six patients underwent coronary angioplasty. A digital end-diastolic acquisition of the coronary artery was performed before, immediately after, at 15 min and at 20 hours after dilatation. Elastic recoil was defined as the difference between the diameter of the inflated balloon and the diameter of the vessel after dilatation. It was quantified by a semi-automatic computer-assisted program. Our data show a high elastic recoil immediately after dilatation, equal to 27.9% (p < 0.0001), which continues for the next 20 hours to a final value of 34.1%. No difference was found in the amount of elastic recoil depending on the coronary artery involved, length, severity and eccentricity of the stenosis, time and pressure used during balloon inflation. Elastic recoil was more pronounced (p = 0.002) using balloons with a balloon diameter/vessel diameter ratio > 1.

Angioplasty, Balloon, Coronary↗
PubMed1992

Alteration of elastic architecture in the lathyritic rat aorta implies the pathogenesis of aortic dissecting aneurysm.

Weanling Sprague-Dawley rats received beta-aminopropionitrile (BAPN) and/or hypertensive treatment, namely, heminephrectomy and administration of deoxycorticosterone acetate-NaCl. The BAPN-treated rats (lathyritic rats) died of dissecting aneurysm, and the victims with hypertensive treatment was greater in number and died earlier than those without the treatment, indicating that the rise of blood pressure promoted the onset of dissecting aneurysm. The elastic architecture of the ascending aortic media was examined not only by transmission electron microscopy with tannic acid stain and/or toluidine blue O stain, but also by scanning electron microscopy after hot formic acid treatment, and the area of interlaminar elastic fibers were morphometrically analyzed by a point counting method using transmission electron microscopic photographs. In the lathyritic rats, interlaminar elastic fibers showed a significant reduction compared with the control rats, and elastic fibers tended to become round-shaped and were frequently spotted with glycosaminoglycan, which suggest a disturbance of elastogenesis. On the other hand, elastic laminae were not disrupted and smooth muscle cells were well preserved. These results suggest that the alteration of the elastic architecture causes an unstable connection between each elastic lamina, and is related to the initiation and the progression of dissecting aneurysm.

Aminopropionitrile↗
PubMed1989

Morphometric analysis of elastic fibers in human skin lymphatic capillaries.

In contrast to their absence near dermal blood capillaries, elastic fibers are commonly seen adjacent to dermal lymphatic capillaries under light microscopy. Based on morphometric analysis, the elastic fiber network that surrounds these skin lymphatic capillaries is predominantly oriented longitudinally to the lymphatic vessel wall. Quantitative analysis reveals that the density of these pericapillary elastic fibers are almost twice that of the intercapillary elastic fibers but only about one-half as thick. These data suggest that dermal lymph capillaries are surrounded by a specific elastic network of functional significance, morphologically distinct from that seen in the intercapillary dermis. Because lymphatic capillaries are often difficult to identify especially when collapsed, this elastic network may facilitate the positive identification of dermal lymphatic capillaries by light microscopy and thereby help differentiate them from blood capillaries. The possible role of this lymphatic elastic network in the absorptive activity of the dermal lymphatic system is also discussed.

Adolescent↗