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At least 865 records · Page 48Linked to original sources
PubMed1995

Lung elastic recoil in normal young adult Chinese compared with Caucasians.

Chinese people have smaller total lung capacity (TLC) compared with Caucasians of similar age, sex and height. One possible reason would be a higher lung elastic recoil in Chinese. Most published values for lung elastic recoil viz static lung compliance (CLst), shape constant K, and maximal static transpulmonary pressure (PLmax) have been from Caucasian subjects. The aim of our study was to obtain values for lung elastic recoil in normal young adult Chinese subjects. Static expiratory pressure-volume (P-V) curves were studied in 22 healthy Chinese subjects (12 males and 10 females). The P-V curve was fitted using an iterative least mean squares regression on a computer, according to an exponential equation: V = A-Be-KP, where V is lung volume, P is transpulmonary pressure, and A, B and K are constants. Mean values +/- SD for K, CLst and PLmax were 0.12 +/- 0.04, 230 +/- 103 ml.cmH2O-1 and 27.5 +/- 7.5 cmH2O, respectively. The values of CLst and K were similar to that of normal Caucasian subjects, whereas values of PLmax were lower. We attributed the lower PLmax partly to weaker inspiratory muscles in Chinese compared with Caucasians. We conclude that lung elastic recoil in normal young adult Chinese is similar to that of healthy young adult Caucasians. Hence, lung elasticity is unlikely to explain the racial differences in static lung volumes.

Adult↗
PubMed1977

The immediate ventilatory response to added inspiratory elastic and resistive loads in preterm infants.

We measured the changes in tidal volume, duration of the various phases of the respiratory cycle, and peak nasal pressure during elastic and resistive loading in preterm infants. Values were calculated during the first loaded breath, when chemical drive was unchanged. Tidal volume decreased by equivalent percentages with resistive loads of 400, 900, and 2,400 cm H2O/liter/sec, and elastic loads of 330, 1,000, and 3,000 cm H2O/liter. Infinite load was also applied (nasal occlusion). Inspiratory duration (ti) was prolonged during resistive loading, as compared with elastic loading (P less than 0.05). Changes in expiratory duration (Te) were not different with both loads (P greater than 0.05). Total duration of the respiratory cycle (T), however, tended to increase in relation to control, more so with resistive loads. Peak nasal pressure was greater with resistive than with elastic loads ( less than 0.025). We suggest that (1) preterm infants, like adult subjects and other animal species, increase inspiratory duration with resistive loads as compared with elastic loads; (2) T of the first loaded breath tends to increase with progressively larger loads and, consequently, instantaneous frequency tends to decrease; and (3) if peak nasal pressure reflects tension developed by the respiratory muscles, then the latter does not offer the inhibitory information needed to terminate inspiration.

Airway Obstruction↗
PubMed1976

Iatrogenic exfoliation of teeth by the incorrect use of orthodontic elastic bands.

Four cases of improper use of elastic bands for minor orthodontic treatment are described. For all the patients, the treated teeth were damaged and local surgical intervention was necessary. To prevent complications when elastic bands are being used, the dentist must provide stabilization of the elastic bands by brackets, bands, or bonded attachments, inform the patient about the possibility of losing the rubber elastic band, and mark the elastic rubber by radiopaque material. Every effort must be made to preserve the damaged anterior teeth by fixation and surgical treatment.

Child↗
PubMed1999

The discrimination, acquisition, and retention of aiming movements made with and without elastic resistance.

Two experiments were conducted to compare the discrimination, acquisition, and retention of movements made with and without elastic resistance. Using methods from psychophysics, Experiment 1 revealed that a discrete 800-mm movement could be discriminated equally precisely when it was performed with and without elastic resistance. Similarly, there was no difference in the spatial accuracy of a discrete aiming movement made with and without elastic resistance when extended practice with knowledge of results (KR) was provided in Experiment 2. Contrary to expectation, when KR about the outcome of the movement was removed on a retention test given 24 h after practice, the accuracy of the movements made with elastic resistance declined much more rapidly than those made without resistance. These findings question the common assumption that elastic resistance is a desirable characteristic of a control mechanism. Actual or potential applications of this research include the design of control mechanisms that facilitate performance under a variety of task and environmental conditions.

Analysis of Variance↗
PubMed2006

Effects of elastic bands on force and power characteristics during the back squat exercise.

Athletes commonly use elastic bands as a training method to increase strength and performance. The purpose of this study was to investigate the effect of elastic bands on peak force (PF), peak power (PP), and peak rate of force development (RFD) during the back-squat exercise (BSE). Ten recreationally resistance-trained subjects (4 women, 6 men, mean age 21.3 +/- 1.5 years) were tested for their 1 repetition maximum (1RM) in the BSE (mean 117.6 +/- 48.2 kg) on a Smith machine. Testing was performed on 2 separate days, with 2 sets of 3 repetitions being performed for each condition. Testing was conducted at 60% and 85% of 1RM with and without using elastic bands. In addition, 2 elastic band loading conditions were tested (B1 and B2) at each of the 2 resistances. No bands (NB) represents where all of the resistance was acquired from free-weights. B1 represents where approximately 80% of the resistance was provided by free-weights, and approximately 20% was provided by bands. B2 represents where approximately 65% of the resistance was provided by free-weights, and approximately 35% was provided from bands. The subjects completed the BSE under each condition, whereas PF, PP, and RFD was recorded using a force platform. There was a significant (p < 0.05) increase in PF between NB-85 and B2-85 of 16%. Between B1-85 and B2-85, PF was increased significantly by 5% (p < 0.05). There was a significant (p < 0.05) increase in PP between NB-85 and B2-85 of 24%. No significant differences were observed in RFD during the 85% conditions or for any of the measured variables during the 60% conditions (p < 0.05). The results suggest that the use of elastic bands in conjunction with free weights can significantly increase PF and PP during the BSE over free-weight resistance alone under certain loading conditions. The greatest differences are observed during the higher loading conditions, with the B1-85 condition appearing to be optimal for athletic performance of the ones we tested. The strength training professional could use variable resistance training (VRT) to increase PF and PP more than the traditional BSE can. VRT could also be used to train these 2 performance characteristics together, which might be especially useful in season, when weight-room training volume can sometimes be limited.

Adult↗
PubMed1994

The potential role of the elastic fiber system in adolescent idiopathic scoliosis.

To assess its possible role in the etiology of adolescent idiopathic scoliosis, the elastic fiber system of the ligamentum flavum was examined in twenty-three patients who had scoliosis and in five age-matched individuals who did not. Elastic fibers are composed of two components: the amorphous core of elastin and microfibrils, of which fibrillin is the primary element. Fresh-frozen histological specimens of ligamentum flavum removed at the time of an operation were examined by Verhoeff staining for elastic fibers and by immunohistochemical staining with use of a monoclonal antibody to fibrillin. Additionally, cultures of fibroblast cells from the ligamentum flavum were used to study the biosynthesis and secretion of fibrillin and its incorporation into the extracellular matrix in vitro. The specimens from one patient did not provide sufficient material for the histological studies; however, fibroblasts were harvested from this specimen. In five (23 percent) of the remaining twenty-two specimens from patients who had adolescent idiopathic scoliosis, Verhoeff staining of elastic fibers showed a marked decrease in fiber density (the number of fibers per unit area) and a non-uniform distribution of fibers throughout the ligament. Eighteen specimens (82 percent) exhibited abnormalities on immunohistochemical staining, including a marked disarrangement of the fibers and a difference in the density of staining, when compared with the control specimens from individuals who did not have adolescent idiopathic scoliosis. Studies of the biosynthesis and secretion of fibrillin and its incorporation into the extracellular matrix in vitro demonstrated that fibroblasts from four (17 percent) of the twenty-three specimens produced normal amounts of fibrillin and secreted it from the cell, but the fibrillin failed to bind to other macromolecules, to form a sedimentable complex, and to incorporate into the extracellular matrix. Collectively, the results suggest the potential role of the elastic fiber system as a component in the pathogenesis of adolescent idiopathic scoliosis in some individuals.

Adolescent↗
PubMed2004

Comparison of titanium elastic nails with traction and a spica cast to treat femoral fractures in children.

BACKGROUND: Titanium elastic nails are commonly used to stabilize femoral fractures in school-aged children, but there have been few studies assessing the risks and benefits of this procedure compared with those of traditional traction and application of a spica cast. This prospective cohort study was designed to evaluate these two methods of treatment, with a specific focus on the first year after injury, the period when the treatment method should have the greatest impact. METHODS: Eighty-three consecutive children, six to sixteen years of age, were studied prospectively. Factors that were analyzed included clinical and radiographic data, complications, hospital charges, and outcome data. Outcome and recovery were assessed both with the American Academy of Orthopaedic Surgeons Pediatric Outcomes Data Collections Instrument, version 2.0, and according to a series of important recovery milestones including the time to walking with aids, time to independent walking, time absent from school, and time until full activity was allowed. RESULTS: Thirty-five children (thirty-five fractures), with a mean age of 8.7 years, were treated with traction and application of a spica cast, and forty-eight children (forty-nine fractures), with a mean age of 10.2 years, were treated with titanium elastic nails. All fractures healed, and no child sustained a complication that was expected to cause permanent disability. At one year after the fracture, eighty of the children had acceptable alignment and no inequality between the lengths of the lower extremities. The remaining three children, who had an unsatisfactory result, had been treated with traction and a spica cast. Twelve patients (34%) treated with traction and a cast had a complication compared with ten patients (21%) treated with titanium elastic nails. Compared with the children treated with traction and a cast, those treated with titanium elastic nails had shorter hospitalization, walked with support sooner, walked independently sooner, and returned to school earlier. These differences were significant (p < 0.0001). We could detect no difference in total hospital charges between the two groups. CONCLUSIONS: The results of this prospective study support the recent empiric observations and published results of retrospective series indicating that a child in whom a femoral fracture is treated with titanium elastic nails achieves recovery milestones significantly faster than a child treated with traction and a spica cast. Hospital charges for the two treatment methods are similar. The complication rate associated with nailing compares favorably with that associated with traction and application of a spica cast.

Adolescent↗
PubMed2004

Intracranial elastance in isoflurane-anesthetized horses.

OBJECTIVE: To determine whether high intracranial pressure (ICP) during spontaneous ventilation (SV) in anesthetized horses coincides with an increase in intracranial elastance (ie, change in ICP per unit change of intracranial volume). ANIMALS: 6 adult horses. PROCEDURE: Anesthesia was induced and maintained in each horse for 5 hours with isoflurane at a constant dose equal to 1.2 times the minimum alveolar concentration. Direct ICP measurements were obtained by use of a strain gauge transducer inserted in the subarachnoid space, and arterial blood pressure was measured from a carotid artery. Physiologic responses were recorded after 15 minutes of normocapnic controlled ventilation (CV) and then after 10 minutes of SV. Aliquots (3 mL) of CSF were removed from each horse during SV until ICP returned to CV values. Slopes of pressure-volume curves yielded intracranial elastance. RESULTS: Intracranial elastance ranged from 0.2 to 3.7 mm Hg/mL after removal of the first aliquot of CSF Slopes of pressure-volume curves were largest following removal of the initial CSF aliquot, but shallow portions of curves were detected at relatively high ICPs (25 to 35 mm Hg). A second-order relationship between SV ICP and initial intracranial elastance was found. CONCLUSIONS AND CLINICAL RELEVANCE: In horses anesthetized with isoflurane, small changes in intracranial volume can cause large changes in ICP Increased intracranial elastance could further exacerbate preexisting intracranial hypertension. However, removal of small volumes of CSF may cause rapid compensatory replacement from other intracranial compartments, which suggests steady-state maintenance of an increase in intracranial volume during isoflurane anesthesia in horses.

Analysis of Variance↗
PubMed1989

Scanning electron microscopic study of hemodynamically induced tears in the internal elastic lamina of rabbit arteries.

A scanning electron microscopic investigation of tears in the internal elastic lamina of the afferent artery of experimental arteriovenous fistulae was undertaken to determine their site of initiation and to elucidate their nature. Carotid-jugular arteriovenous fistulae and contralateral common carotid arteriotomies were performed in rabbits sacrificed from two to 63 days post-operatively. Following de-endothelialization, scanning electron microscopy of the internal elastic lamina revealed predominantly transverse straight tears with sharp margins. Even in chronic fistulae the tears retained their sharp margins despite their propagation. No evidence of repair was observed. The tears commenced by rupture of the elastic trabeculae traversing the fenestrae. Enzymatic digestion of the internal elastic lamina did not resemble the hemodynamically induced tears and no evidence of elastolytic enzyme activity was detected. The tears suggest that the abnormally stressed elastic tissue has undergone some structural alteration leading to a reduction in its tensile strength.

Animals↗
PubMed1999

[Elastic band ligation in secondary prevention of esophageal varices hemorrhage].

BACKGROUND: Sclerotization of esophageal varices may result in serious esophageal destruction. Elastic band ligation of esophageal varices is recently used in similar indications. AIM: The aim of the study was to evaluate in a pilot study the efficacy and safety of elastic band ligation for secondary prevention of bleeding from esophageal varices in patients who experienced life-threatening and were not yet treated with elastic band ligation. PATIENTS AND METHODS: Saeed's method of elastic band ligation was used in 10 patients (5 men and 5 women) aged from 16-60, who had already experienced life-threatening esophageal varices hemorrhage. One patient awaiting liver transplantation underwent preventive ligation. RESULTS: Esophageal varices were eradicated in 5 patients, minimum range residual varices remained in 4 patients after ligation. Haemorrhage recurrence was observed in 4 patients and was successfully treated by single urgent sclerotization. Two patients developed neo-varices. The ligation program was stopped in one female patient with mitral stenosis and tricuspidal insufficiency because of stenocardias occurring during ligation. In one session, 4.5 elastic bands in average were applied. The treatment of one patient required 4 sessions during 2.5 months in average. CONCLUSION: Elasic band ligation is an effective and safe method for the treatment of esophageal varices. Short term results are promising. (Tab. 1, Fig. 1, Ref. 18.)

Adolescent↗
PubMed2000

SEM demonstration of elastic fibres in the integument of small and densely-haired mammals.

The combination of SEM and autoclave methods gave a clear three-dimensional demonstration of integumental elastic fibres in small densely-haired mammals. The specific organisation of a fine and spongy elastic network was characterised by uniformly thin elastic fibres which were homogeneously distributed between both hair follicle types throughout the whole dermis. All the hair follicles were connected with each other by elastic fibres along their complete intradermal length. The advantage of such a specific elastic dermis construction is that all hair follicles can be moved together and simultaneously along the entire body, so that a better and rapid insulation is achieved after erection of the hair follicles during very low temperatures.

Animals↗
PubMed1991

[Behaviour of gingival elastic constituents in periodontal disease].

Disorganization of gingival elastic constituents, including oxytalan fibers, elaunin fibers, and mature elastic fibers, is a feature of periodontal disease. In early stages where inflammation is moderate, this disorganization involves only oxytalan fibers. As the disease progresses, fragmentation and lamination of elaunin fibers and mature elastic fibers is seen. In cyclosporin A-induced gingival hyperplasia, there is a substantial increase in the amount of elastic fibers as compared with healthy gingiva. In gingival fragments from edentulous elderly individuals the elastic constituents form dense granules.

Adult↗
PubMed1990

The effects of elastic tights on the post-exercise response.

It has previously been demonstrated that graduated compression stockings will affect the post-exercise venous lactate profile. To determine the effects of elastic tights on venous lactate levels and the post-exercise response, eight males completed three exercise bouts on a motor driven treadmill. Each subject ran on the treadmill for up to three minutes at 110% of his VO2max. The conditions for the three exercise bouts were: elastic tights worn during exercise and recovery, elastic tights worn only during exercise, and no elastic tights worn during exercise or recovery. Oxygen consumption, heart rates and venous blood samples, for lactate and hematocrit determination, were obtained at rest and at 5, 15 and 30 min post-exercise. Analysis revealed no significant differences (p greater than 0.05) in any of the above variables between the three trials at any of the measurement times. These results indicate that the use of elastic tights will not significantly affect the post-exercise response or circulating lactate levels.

Adult↗
PubMed1990

Elastic bandages and intermittent pneumatic compression for treatment of acute ankle sprains.

The efficacy of elastic bandage alone and with intermittent pneumatic compression (IPC) treatments in the rehabilitation of 44 acute ankle sprains was studied. Lower-leg dysfunction was assessed by measurements of edema, degree of ankle motion, pain, and limb dysfunction when the patient was first included in the study, after treatment for one week, and after a four-week follow-up. For all the parameters studied, elastic bandage with IPC treatment resulted in highly significantly (p less than 0.001) faster rehabilitation during the four-week follow-up than did elastic bandage treatment alone. The limb dysfunction improved significantly (p less than 0.01) during the follow-up on the study group receiving IPC with elastic bandage compared to elastic bandage alone. The results suggest that IPC treatment is effective in acute posttraumatic therapy.

Adult↗
PubMed1990

[The effect of procyanidolic oligomers on mesenchymal cells in culture. II--Attachment of elastic fibers to the cells].

Tissues are composed of cells and extracellular matrix (EM). Adhesion of cells to extracellular matrix is mediated by membrane-bound glycoproteins such as fibronectin, laminin and others. Elastonectin was shown recently to be involved in the mediation of interactions between elastic fibers and cells such as human skin fibroblasts (FB) and smooth muscle cells (SMC) from the media of the aorta. A strong interaction between fibers and cells is important for the maintenance of the quality of the vascular wall. We studied the action of procyanidolic oligomers (PCO) on the attachment of fibroblasts from human skin and smooth muscle cells from porcin aorta to elastic fibers. A dose-dependent increase of cell-fiber interaction could be demonstrated with both cell-types. Elastonectin is located on the cell membrane as well as an elastolytic serine-protease exhibiting an age- and pathology-dependent increase in activity. This will result in a degradation of elastic lamellae, the detachment of cells from elastic fibers and a weakening of the vascular wall. The activity of procyanidolic oligomers increasing the resistance of elastic fibers to degradation by elastases and enhancing the interaction between fibers and cells can be considered as favouring the maintenance of the normal functional state of the vascular wall.

Adult↗
PubMed1994

Acute and long-term effect of elastic stockings in patients with varicose veins.

The acute and long-term effect of elastic stockings has been evaluated in 20 patients (20 limbs) with grade 2 venous disease. The sites of venous reflux were determined with colour flow duplex scanning. Air Plethysmography was used to measure the amount of venous reflux and the ejecting capacity of the calf muscle pump. The patients were classified in to two different groups, A and B. Both groups of patients wore elastic stockings for four weeks. In group A (no. = 9) the measurements were done before, during and one day after the removal of the stockings, whereas in group B (no. = 11) the last measurements were done immediately after the removal of the stockings. Patients that showed improvement in their haemodynamics were re-examined a week later. Elastic compression appeared to be beneficial in both groups. The application of the elastic stockings improved reflux and the residual volume fraction in both groups and the ejecting capacity of the calf muscle pump in group B. Immediately after the removal of the stockings (Group B) all the measurements regressed to the initial values with the exemption of the residual volume fraction. However, one week later, the latter also regressed to the original value. It is concluded that the beneficial effect of elastic stockings on the venous haemodynamics is present mainly when the stockings are worn. It is completely abolished within a day after their removal.

Bandages↗
PubMed1996

[Effect of high insufflation pressures on elastic recoil forces and vascular resistance after balloon dilatation].

In this study, we examined whether percutaneous coronary angioplasty (PTCA) of native coronary arteries with high inflation pressure can improve the immediate postinterventional result in comparison to PTCA with nominal inflation pressure. Using quantitative coronary angiography, we analyzed the coronary angiograms of 24 patients who underwent PTCA with nominal inflation pressure (< 10 atm; group 1) and of 20 patients who underwent PTCA with high inflation pressure (> or = 10 atm; group 2). Only balloon catheters with little compliance were used. The following variables were recorded: 1) minimal luminal diameter (MLD), reference diameter and percent diameter stenosis before and after PTCA, 2) average balloon diameter during PTCA, 3) balloon/artery diameter ratio, 4) acute luminal gain (difference between MLD before and after PTCA), 5) nominal elastic recoil (difference between nominal balloon diameter and MLD after PTCA), 6) actual elastic recoil (difference between average balloon diameter during PTCA and MLD after PTCA). Nominal balloon diameter, reference diameter before and after PTCA and the balloon/artery diameter ratio were similar in both groups. Application of high inflation pressure resulted in a greater average balloon diameter. In group 2 (high inflation pressure), average balloon diameter amounted to 94 +/- 12% of nominal balloon diameter, whereas in group 1 (nominal inflation pressure), it reached only 84 +/- 9% of nominal balloon diameter. Actual elastic recoil was not different between the two groups. Nominal elastic recoil, however, was greater in the cohort which received PTCA with nominal inflation pressure (1.13 +/- 0.35 mm vs. 0.83 +/- 0.28 mm; p < 0.02). After use of high inflation pressure, acute postinterventional luminal gain was significantly increased (1.04 +/- 0.25 mm vs. 0.77 +/- 0.34 mm; p < 0.02) and the postinterventional percent diameter stenosis was significantly lower (12 +/- 10% vs. 24 +/- 13%; p < 0.05). Application of high inflation pressure improves the postinterventional result after PTCA because of a greater acute luminal gain. The stenotic coronary artery is expanded to a greater degree, and actual elastic recoil remains unchanged.

Adult↗
PubMed1996

Elastic fibres are an essential component of human placental stem villous stroma and an integrated part of the perivascular contractile sheath.

The stroma of human placental stem villi is believed to consist only of reticular and collagen fibres. In the present study we were able to show for the first time by light (orcein staining) and electron microscopy large amounts of elastic fibres in the stem villous stroma. Electron microscopically, homogeneous elastin was found alone or in association with microfibrils. In addition, microfibrils were observed forming long bands. These three structures, generally known to form elastic connective tissue, were seen in close connection with placental extravascular smooth muscle cells, which belong to the perivascular contractile sheath (PVCS) of stem villi. Elastin was associated with these smooth muscle cells and connected to collagen fibres via microfibrils. Collagen fibres were additionally interconnected by spike-like structures. Extravascular smooth muscle cells revealed numerous adhesion plaques which occupied conspicuously long cytoplasmic faces of the plasma membrane. In cryostat sections, immunoreactivity of talin, an attachment protein of adhesion plaques linking intracellular alpha-actin filaments with extracellular fibronectin, was detected in extravascular and vascular (media) smooth muscle cells. The arrangement of placental extravascular smooth muscle cells, elastic and collagen fibres suggests a functional myofibroelastic unit within the PVCS, which surrounds the large foetal blood vessels possibly contributing to elasticity and supporting tensile and/or contracting forces within the stem villi.

Actins↗