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Results for “Elastic Tissue”

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At least 325 records · Page 18Linked to original sources
PubMed2004

The value of an elastic tissue stain in detecting venous invasion in colorectal cancer.

BACKGROUND: Venous invasion by tumour is an independent prognostic indicator of both prognosis and risk of development of distant metastases in colorectal carcinoma. The use of special stains to aid its detection in pathology specimens is not currently universally recommended. AIMS: To determine whether an elastica stain significantly increases the incidence of detection of vascular invasion compared with routinely stained sections. METHODS: Serial sections from the 75 cases of colorectal carcinoma were stained by haematoxylin and eosin (H&E) only and elastica counterstained with H&E. The incidence of both intramural and extramural venous invasion was recorded and compared with that seen when the tumours were originally reported. RESULTS: Extramural venous invasion had been noted in 14 of the pathology reports and was seen in 18 cases when only the H&E sections were viewed in the study. It was present in 32 cases when elastica stained sections were analysed. Intramural venous invasion was seen in eight cases on H&E sections and 30 cases on elastica stained sections. CONCLUSION: The use of elastica stained serial sections to detect venous invasion in tumours should be recommended in guidelines for the reporting of colorectal carcinomas.

Blood Vessels↗
PubMed1982

[Changes in the elastic tissue of patients with Down's syndrome].

Two patients with Down's syndrome are reported. A concomitant finding in one of them was psoriasis (not frequent in these patients), anetoderma and unelastic connective tissue nevi. Anetoderma was the only concomitant finding in the other patients. On the basis of these findings the authors feel that besides the "stigmata" referred to, patients with Down's syndrome may present congenital malformation of the elastic fibers. Another objective of this paper is to suggest that every one of these patients should be submitted to a through dermatological investigation having regard to the highly varied and interesting skin changes likely to be disclosed.

Adult↗
PubMed2000

Vertebral trabecular bone microscopic tissue elastic modulus and hardness do not change in ovariectomized rats.

Ovariectomized rats have been used extensively and have received substantial acceptance as animal models for postmenopausal osteoporosis. However, little is known about the microscopic tissue properties of rat vertebral bone, especially during osteoporosis caused by estrogen depletion. This study applied a new nanoindentation technique to quantify the microscopic mechanical properties of vertebral trabecular bone tissue in ovariectomized rats. Seventeen-week-old Sprague-Dawley rats underwent an ovariectomy. After death at 37 weeks, the fraction of the trabecular bone area of the lumbar vertebrae (L4) was measured with scanning electron microscopy and the elastic modulus and hardness were determined with the nanoindentation technique. The bone area fraction was reduced significantly after the ovariectomy. However, the elastic modulus and hardness did not change significantly at the microscopic level. The results indicate that estrogen-dependent osteoporosis in rats manifests in a loss of bone mass whereas the elastic and hardness properties of the surviving bone tissue remain relatively unchanged.

Animals↗
PubMed2000

Non-invasive quantitative reconstruction of tissue elasticity using an iterative forward approach.

A novel iterative approach is presented to estimate Young's modulus in homogeneous soft tissues using vibration sonoelastography. A low-frequency (below 100 Hz) external vibration is applied and three or more consecutive frames of B-scan image data are recorded. The internal vibrational motion of the soft tissue structures is calculated from 2D displacements between pairs of consecutive frames, which are estimated using a mesh-based speckle tracking method. An iterative forward finite element approach has been developed to reconstruct Young's modulus from the measured vibrational motion. This is accomplished by subdividing the 2D image domain into sample blocks in which Young's modulus is assumed to be constant. Because the finite element equations are internally consistent, boundary values other than displacement are not required. The sensitivity of the results to Poisson's ratio and the damping coefficient (viscosity) is investigated. The approach is verified using simulated displacement data and using data from tissue-mimicking phantoms.

Algorithms↗
PubMed1999

Objective assessment of limb tissue elasticity: development of a manual indentation procedure.

An ultrasound indentation system with a pen-size hand-held probe was developed and used to obtain the effective Young's moduli of forearm and lower limb soft tissues in 12 subjects. Since the probe is manually driven, the alignment of the probe and control of the rate of indentation are parameters upon which the results obtained depend. This paper addresses whether manual indentation tests with the probe are sufficiently acceptable and repeatable for objective biomechanical characterization of limb tissues. Forearms of three normal subjects were tested in two states of muscular contraction. Six different indentation rates, ranging from 0.75 mm/s to 7.5 mm/s, were imposed. The load-indentation responses obtained were shown to be well represented by quadratic functions. A linear elastic indentation solution was used to extract the effective Young's modulus. The material parameters extracted were repeatable and rather rate-insensitive for the range of rates used. The effective Young's modulus obtained was found to significantly increase as a result of contraction of the underlying muscles. Indentor misalignment experiments demonstrated that misalignment affects the measurement from which the effective Young's modulus of soft tissues is calculated. This effect, however, was found to decrease as the tissue thickness increased. With the investigation of the above issues, a procedure has been established for the extraction of effective Young's moduli of limb soft tissues from manual cyclic indentation responses. Tests on experimental subjects' lower limbs further demonstrated that the ultrasonic indentor is a feasible instrument for characterization of the biomechanical properties of limb soft tissues. Paired-t tests showed that the effective Young's moduli of the lower limb soft tissues of three elderly persons with transtibial amputation were significantly smaller than those of six unimpaired young subjects.

Adult↗
PubMedDate not supplied

Lung tissue elasticity during the lifespan of Fischer 344 rats.

Fischer 344 rats at 1 week, 6 weeks, 5 months, 14 months, and 22 months of age were studied. Lung wet and dry weights and lung volumes increased with age. As rats grew older, saline volume-pressure (V-P) curves expressed as percent maximal lung volume shifted progressively upward and to the left and tissue recoil decreased over the upper and mid portions of the V-P relationships. Specific lung compliance increased until 5 months of age but did not change afterward. DNA content of the lung increased progressively until 5 months of age but decreased in older rats. Protein content of the lung increased significantly with age, while hydroxyproline and crude connective tissue content of the lung increased progressively until 14 months of age. Decreased tissue recoil and increased lung volume and lung compliance with age, in face of an increase in connective tissue proteins, suggest that larger air space dimensions might be responsible for changes in lung mechanics in aging rats.

Aging↗
PubMed2006

Tissue elasticity imaging for diagnosis of prostate cancer: a preliminary report.

BACKGROUND: Elastography is a diagnostic imaging technique that evaluates the hardness of a lesion. It is expected to become a new diagnostic modality for prostate cancer. The aim of this study was to examine the usefulness of elastography in the diagnosis of prostate cancer. METHODS: A total of 29 patients with untreated, histologically proven prostate cancer were examined using an elastographic imaging technique. The patient was scanned in the dorsosacral position and the prostate was manually compressed with a transrectal ultrasonic probe. The echo signals from inside the tissue were measured before and after the tissue compression and an elastogram was generated by spatially differentiation of the displacement distribution. RESULTS: Elastography depicted the cancer lesion as a harder tissue than the surrounding normal prostatic tissue. Elastography successfully detected 93% (27 patients) of the untreated prostate cancer lesions. Detection of cancer lesions using elastography was significantly higher than by digital rectal examination (59%; 17 patients) and transrectal ultrasonography (55%; 16 patients). CONCLUSION: Elastography has great potential as a useful modality for diagnosis of prostate cancer. Differentiation between cancerous and normal tissues can be expected to become more accurate as a result of technical advances in the quantification of tissue hardness.

Aged↗
PubMed2006

Does elastic tissue intrafraction motion with density changes forbid motion-compensated radiotherapy?

Intrafraction organ motion disturbs the otherwise highly conformal dose distributions planned for conformal radiotherapy and intensity-modulated radiotherapy. If the organ motions are rigid-body translations and preserve voxel density, techniques to make the beam follow the target by synchronous breathing can be arranged. Several potential difficulties disturb this oversimple statement and one of these is addressed in this paper. The effects of general elastic motion without preserving density are investigated. The effects are complex. Dose-space voxels disconnect from the planned irradiation bixel; voxels in a set aligned with a particular bixel cease to be so aligned even with a different bixel on elastic motion. Furthermore the density changes to conserve mass and this further perturbs the dose distribution. These effects are demonstrated here via simple examples but it may be impossible to make 'beam-breathing' strategies to compensate for them. Consequently understanding (and possibly ignoring) these second-order effects may be all that is possible.

Algorithms↗
PubMed1988

Abnormal elastic tissue in cartilage-hair hypoplasia.

A 29-year-old white woman had short limbs, hyperextendable joints, fine skin and body hair, anergy to common skin test antigens, subnormal lymphocyte response to phytohemagglutinin, and increased numbers of natural killer cells, characteristic of cartilage-hair hypoplasia, an autosomal, recessively inherited disorder found in America mainly among the old-order Amish. Her forearm skin was hyperextendable and numerous verrucae were present on the digits of her hands. A skin biopsy from hyperextendable skin showed ovoid, 10- to 20-micron bodies in the papillary dermis. Ultrastructurally, the bodies were interpreted as abnormal elastic fibers.

Adult↗
PubMed1984

The binding of Evans blue to collagen and elastin in elastic tissue.

The binding of Evans blue to collagen and elastin in rabbit aortic tissue and in bovine ligamentum nuchae was studied following circulation in vivo of the dye and incubation in vitro in Evans blue containing plasma, respectively. Using collagenase and elastase, the dye was liberated from both tissues corresponding to their different contents of collagen and elastin. Disc electrophoretic analysis of the liberated dye showed, that it migrated as free Evans blue indicating that the binding of the dye to the macromolecules was due to spatial interactions rather than to fixation at specific prosthetic groups. The capability of collagen and elastin to bind Evans blue was demonstrated with the isolated proteins; it was shown elastin had a higher affinity to the dye than collagen. Treatment of the blued tissue with hyaluronidase and Triton X-100 showed that binding to complex carbohydrates and dye accumulation in the aqueous intra- or extracellular space seems to be negligible.

Animals↗