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PubMed1996

Imaging of the elastic properties of tissue--a review.

Recently, a number of methods have been developed that make it possible to image the elastic properties of soft tissues. Because certain types of tissues such as malignant lesions, for example, have elastic properties that are markedly different from surrounding tissues, elasticity imaging could provide a significant adjunct to current diagnostic ultrasonic methods. Further, elasticity imaging techniques could be used to augment the study of tissues that change their elastic properties, such as skeletal and cardiac muscle. In this paper, we survey some of the previous work done in the related field of biomechanics, and we review measurement techniques from the 1950s to the 1980s. Different approaches to elastic imaging and signal processing are then discussed and a lexicography for elastic imaging is introduced. It is hoped that this nomenclature will provide a meaningful categorization of various approaches and will make evident the inherent parameters displayed and conditions applied in deriving the resulting images. Key assumptions and signal processing approaches are also reviewed. Finally, directions for future work are suggested.

Animals↗
PubMed1991

Anetodermic cutaneous changes overlying pilomatricomas.

Five pilomatricomas with anetodermic cutaneous changes and striae are presented. Pink to translucent, atrophic, scarlike skin that covers a typical pilomatricoma occurs most commonly in young women. Histopathologic examination showed an atrophic, edematous dermis with diminished, fragmented collagen fibers and absent elastic tissue.

Adolescent↗
PubMed2001

Management of Peyronie's disease--a review.

Peyronie's disease is an uncommon condition involving middle-aged men and probably resulting from penile trauma. The injury causes an inflammation in the tunica and ultimately scarring and penile curvature develop. It may also occur due to nonspecific inflammation. The use of medications such as beta-blockers can sometimes result in Peyronie's disease. In Peyronie's disease, the normal elastic tissue of the tunica is replaced by scar tissue. The penile plaque, or scar tissue in this condition, is not elastic but hard and will not stretch with erection. The side that does not stretch results in penile curvature to the side of the scar. One third of men with Peyronie's disease have painful erections. A low percentage of men with Peyronie's disease develop erectile dysfunction. Because inflammation is initially associated with the scar tissue, some amount of discomfort occurs during erection. Most patients with early stage Peyronie's disease can continue to function sexually with the curvature in the penis. Others with a severe penile deformity will have difficulty in sexual intercourse. Literature regarding the effectiveness of conservative therapy in the early phase with pain and inflammation is limited, with only modest and at times anecdotal benefits. The commonly used agents include 400 units of vitamin E (vitamin E promotes healing and prevents scarring), ibuprofen (anti-inflammatory) and Colchicine (useful for pain during erection). Fexofenadine is recently being used in the early phase of Peyronie's disease for its antiinflammatory effect. Radiation and ultrasound are not usually very helpful. When the disease process stops, there is usually some residual distortion of the penis but the majority of patients are able to have satisfactory sexual intercourse. However, if there is severe penile distortion interfering with intercourse, surgery is indicated. Surgical techniques for Peyronie's disease include tightening or plication (Nesbit's tuck) of the penis opposite the curvature to produce straightening. This usually results in some small loss of length. The other type of surgery consists of incision of the plaque or scar tissue and patching with a vein (saphenous vein graft) or dermal graft. Laser therapy is occasionally used. A penile prosthesis is the treatment of choice in patients with Peyronie's disease and erectile dysfunction.

Erectile Dysfunction↗
PubMed1991

Ultrastructural changes of the patellar tendon as a cruciate ligament substitute (one year and two year results).

In four black-faced sheep, the posterior cruciate ligament was replaced with a free autogenous patellar tendon transplant. Tissue samples from the transplants were investigated by light and electron microscopy 1 year and 2 years after surgery. The normal contralateral posterior cruciate ligament and the normal contralateral patellar tendon were used as controls. The structural differences concerned cells, collagen fibrils, elastic tissue and proteoglycans. Most of the cells of the contralateral patellar tendon were spindle-shaped, whereas those of the transplant were frequently chondroid. In the central region of the transplant as well as in the area far from the bone, cell degenerations, and occasionally hypo- or even acellular zones were found. Measurements of the diameter of collagen fibrils in both contralateral patellar tendon and posterior cruciate ligament showed a more or less pronounced bimodal distribution. A unimodal distribution with mainly thin fibrils (20-60 nm) was demonstrated in the transplant tissue which also revealed some morphological alterations of the collagen fibrils. Thin elastic fibers (microfibrils and amorphous material) were randomly scattered among the collagen fibrils of the control samples, bundles of microfibrils (without amorphous material) characterized the transplant. Staining with Alcian blue in the presence of 0.3 M MgCl2 demonstrated a close relationship between proteoglycans and collagen fibrils as well as elastic components in patellar tendon. This arrangement was lost in the transplant where abundant proteoglycans were revealed which, however, composed a tight irregular network between the collagen fibrils. The results serve as a baseline for understanding the impaired biochemical properties of a free autogenous patellar tendon transplant.

Animals↗
PubMed2003

[Prostate cancer diagnosis using ultrasound elastography. Introduction of a novel technique and first clinical results].

During the last decade screening has improved prostate cancer detection. The main reason for this development is a better understanding of the margins of prostate-specific antigen (PSA) serum levels and the classification of PSA subtypes. In contrast, the introduction of transrectal ultrasound has not led to a measurable change in the prostate cancer detection rate. Our aim was to develop a novel ultrasound system for the acquisition of elastographic images of the prostate and evaluate the system regarding its clinical applicability. We used a technically modified conventional ultrasound system and analyzed the high-frequency ultrasonic data with a computer program. The first patient-based results suggest that elastography allows an accurate measurement of tumor size and localization in contrast to conventional transrectal ultrasound. Elastography visualizes different tissue elasticities to distinguish benign and cancerous tissue. Thus, we were able to even correctly classify prostate cancer lesions which are iso- or hyperechoic in B-mode sonography.

Aged↗
PubMed1991

Elastosis in the normal aging breast. A histopathologic study of 140 cases.

The incidence and pattern of elastosis of the breast was studied in tissue specimens taken at autopsy from 140 women with clinically normal breasts, ranging in age from 19 through 101 years. Elastosis, presence of excess elastic fibers, while less common in younger women, may be found in nearly half of all women over age 50 years with no breast disease. Elastosis occurs in three sites: diffusely in the stroma, around vessels, and around ducts. In the first two sites, it bears little relationship to age, while periductal elastic tissue appears to accumulate with age, probably reflecting parity, until about age 50 years. Thereafter, it is found at a more or less constant incidence and degree. While it may be associated with breast cancer, periductal elastosis by itself is not a cause for concern. Marked perivascular elastosis is, however, uncommon at any age, and its presence should suggest a special search for carcinoma, if not already evident.

Aging↗
PubMed1986

SEM observations of the elastic networks in canine femoral artery.

Scanning electron microscopy was used to study the normal architectural arrangement of elastic tissue in a medium-sized muscular artery. Selective NaOH sonication digestion or formic acid digestion was used to expose and isolate the elastic networks in the femoral arteries of four healthy dogs. The digested segments were neutralized and freeze-dried before mounting for scanning electron microscopy (SEM) observation. The fenestrated internal elastic lamina (IEL) had a smooth surface with scattered regions of the fine elastic fibers that made up lacy networks protruding from the luminal surface. Prominent ellipsoid fenestrae, randomly scattered across the surface, were grouped into small and large sizes based on their mean diameter. The openings of most fenestrae were bridged by elastic fibers to give the fenestrae a sieve-like appearance. Large, transversely oriented, fusiform gaps were randomly scattered along the length of the IEL. These gaps, filled in by an elastic fiber network, sometimes spanned as much as a quarter of the vessel circumference. It is suggested that these gaps represent splits in the IEL that have been repaired. The tunica media contained a complex network of anastomosing elastic fibers and lamellae that were primarily circumferential in orientation. A well-defined external elastic lamina formed a solid sheet at the junction of the tunica media and the tunica adventitia. The tunica adventitia contained 8-10 incomplete lamellae of large, interconnecting, longitudinally oriented fibers. The architecture of the elastic network in canine femoral artery was compared with that previously described in medium-sized canine veins and in the rat femoral artery.

Animals↗
PubMed2005

Ventricle and outflow tract of the African lungfish Protopterus dolloi.

We report a morphologic study of the heart ventricle and outflow tract of the African lungfish Protopterus dolloi. The ventricle is saccular and appears attached to the anterior pericardial wall by a thick tendon. An incomplete septum divides the ventricle into two chambers. Both the free ventricular wall and the incomplete ventricular septum are entirely trabeculated. Only a thin rim of myocardium separates the trabecular system from the subepicardial space. The outflow tract consists of proximal, middle, and distal portions, separated by two flexures, proximal and distal. The proximal outflow tract portion is endowed with a layer of compact, well-vascularized myocardium. This portion is homologous to the conus arteriosus observed in the heart of most vertebrates. The middle and distal outflow tract portions are arterial-like, thus being homologous to the bulbus arteriosus. However, the separation between the muscular and arterial portions of the outflow tract is not complete in the lungfish. A thin layer of myocardium covers the arterial tissue, and a thin layer of elastic tissue underlies the conus myocardium. Two unequal ridges composed of loose connective tissue, the spiral and bulbar folds, run the length of the outflow tract. They form an incomplete division of the outflow tract, but fuse at the distal end. The two folds are covered by endocardium and contain collagen, elastin, and fibroblast-like cells. They appear to be homologous to the dextro-dorsal and sinistro-ventral ridges observed during the development of the avian and mammalian heart. Two to three rows of vestigial arterial-like valves appear in the dorsal and ventral aspects of the conus. These valves are unlikely to have a functional role. The possible functional significance of the "gubernaculum cordis," the thick tendon extending between the anterior ventricular surface and the pericardium, is discussed.

Animals↗
PubMed2001

A novel Q378X mutation exists in the transmembrane transporter protein ABCC6 and its pseudogene: implications for mutation analysis in pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is an inherited disorder of the elastic tissue with characteristic progressive calcification of elastic fibers in skin, eye, and the cardiovascular system. Recently mutations in the ABCC6 gene, encoding a transmembrane transporter protein, were identified as cause of the disease. Surprisingly, sequence and RFLP analysis for exon 9 with primers corresponding to flanking intronic sequence in diseased and haplotype negative members from all of our families and in a control population revealed either a homozygous or heterozygous state for the Q378X (1132C-->T) nonsense mutation in all individuals. With the publication of the genomic structure of the PXE locus we had identified the starting point of a large genomic segmental duplication within the locus in the cytogenetic interval defined by the Cy19 and Cy185 somatic cell hybrid breakpoints on chromosome 16p13.1. By means of somatic cell hybrid mapping we located this starting point telomeric to exon 10 of ABCC6. The duplication, however, does not include exon 10, but exons 1-9. These findings suggest that one or several copies of an ABCC6 pseudogene (psiABCC6) lie within this large segmental duplication. At least one copy contains exons 1-9 and maps to the chromosomal interval defined by the Cy163 and Cy11 breakpoints. Either this copy and/or an additional copy of psiABCC6 within Cy19-Cy183 carries the Q378X mutation that masks the correct identification of this nonsense mutation as being causative in pseudoxanthoma elasticum. Long-range PCR of exon 9 starting from sequence outside the genomic replication circumvents interference from the psiABCC6 DNA sequences and demonstrates that the Q378X mutation in the ABCC6 gene is associated with PXE in some families. These findings lead us to propose that gene conversion mechanisms from psiABCC6 to ABCC6 play a functional role in mutations causing PXE.

Alleles↗
PubMed1997

Mapping of both autosomal recessive and dominant variants of pseudoxanthoma elasticum to chromosome 16p13.1.

Pseudoxanthoma elasticum (PXE) is a classic inherited disorder of the elastic tissue characterized by progressive calcification of elastic fibers with a pathognomonic histological appearance. The clinical manifestations of PXE typically involve the skin, the eye and the cardiovascular system, resulting in skin lesions, decreased vision and vascular disease. Clinically, a more common autosomal recessive and a less common autosomal dominant pattern of inheritance, with high penetrance, have been described; the estimated prevalence of the disease is 1 in 70,000-100,000. Previous failure to link the disease to any of several candidate genes prompted us to conduct a genome-wide screen on a collection of 38 families with two or more affected siblings, using allele sharing algorithms. Excess allele sharing was found on the short arm of chromosome 16 and confirmed by conventional linkage analysis, localizing the disease gene under a recessive model with a maximum two point lod score of 21.27 on chromosome 16p13.1, an area so far devoid of any obvious candidate genes. Under a dominant transmission pattern linkage with a maximum two point lod score of 14.53 was observed to the same region. Linkage heterogeneity analysis predicted the presence of allelic heterogeneity with different variants of a single gene that resides in this chromosomal region accounting for recessive and dominant forms of PXE.

Adult↗
PubMed1983

Peripheral nerve as an osmometer: role of the perineurium in frog sciatic nerve.

Measurements of volume and hydrostatic pressure in the frog sciatic nerve in vitro demonstrate that the nerve acts as an osmometer, in large part because the perineurium is a semipermeable membrane for water flow. Endoneurial hydrostatic pressure in nerves in isotonic Ringer exceeds bath pressure by about 7 mmHg. In Ringer made hypertonic by addition of sucrose, nerve volume and endoneurial pressure fall linearly in relation to 1/osmolality. The slope of the plot of pressure against volume provides a value for nerve compliance equal to 0.006 mm2/mmHg. Calculations based on the model of the nerve as an osmometer indicate that the nerve has an osmotically "inactive" volume equal to 0.19 mm3/mm, which is about 75% of the total volume of a nerve segment of unit length in normal Ringer. Perineurial hydraulic conductivity (Lp) equals 7.5 x 10(-13) cm3.s-1.dyn-1, a value characteristic of nonleaky epithelia. The perineurium is an elastic tissue with a constant modulus of elasticity equal to 3 x 10(6) dyn/cm2 when not markedly stretched and may limit nerve swelling under pathological conditions of nerve edema.

Animals↗
PubMed1992

Endothelium and elastic tears in the afferent arteries of experimental arteriovenous fistulae in rabbits.

The endothelium and underlying internal elastic lamina of the arteries from 16 carotid-jugular arteriovenous fistulae in rabbits were examined using the en face technique and scanning electron microscopy respectively. Tears appeared in the internal elastic lamina of the arteries 3 days post-operatively. The overlying endothelium exhibited cytoplasmic pallor, loss of argyrophilia of cell borders, and at times attenuated endothelial cells bridging thrombus covered regions of denudation. Early endothelial lesions repaired rapidly and were found only 3-7 days post-operatively despite progressive increase in frequency and extent of tears and the development of interconnecting longitudinal tears with time. Following repair endothelial cells over the tears were small with hyperchromatic nuclei and oriented mostly parallel to the arterial axis. Endothelial cell density overlying these elastic tissue tears increase to three times that in contralateral arteriotomized common carotid arteries. These endothelial changes were sharply delineated by the margins of the elastic tears. Cell density over the tears reached its maximum 9-11 days post-operatively with mitotic figures both in the floor of the tears and over islands of residual elastic lamina. With time the cell density progressively diminished and endothelial cells assumed a more conventional elongated spindle shape.

Animals↗
PubMed1982

The effect of beta-aminoproprionitrile on the lingual artery and aorta of the rat: a light microscopic study.

The effects of chronic toxicity of beta-aminoproprionitrile (BAPN) on the lingual artery and aorta of the rat were compared. Thirty-two three week old weanling male white Wistar rats were given 1 g/kg/day (for five days weekly) of a 40% saturated solution of BAPN fumarate by intragastric tube. The animals were divided into four groups of eight animals each and sacrificed after one, three, six and nine weeks respectively. For each group, four controls were used. Cross-sections of the lingual artery and aorta stained with hematoxylin-erythrosin-safranin, alcian blue, Masson's trichrome and Verhoeff's iron hematoxylin were studied. BAPN had no effect on the lingual artery. Early changes were seen in the aorta at six weeks. Characteristic lesions were found at nine weeks involving the elastic tissue, myocytes and ground substance. The elastic lamellae were thinner, lost their normal orientation, and became swollen and finally fragmented. The myocytes of the media changed orientation and migrated into the intima. The proteoglycans increased and fibrosis supervened at the end stage. Failure to induce lesions in the lingual artery may be explained by early structural maturation and a low metabolic turnover rate in muscular arteries, decreased exposure to or greater protection from mechanical stress.

Aminopropionitrile↗
PubMed1997

[Pseudoxanthoma elasticum: a rare cause of leg artery diseases in young adults].

Pseudoxanthoma elasticum (PXE) is a rare inherited connective tissue disorder which is characterized by elastic tissue degeneration involving the skin, eyes and arteries. We describe the case of a hypercholesterolemic 25 year-old woman with typical genetic dominant form of PXE revealed by distal limb artery involvement after a pregnancy. In young adults with arterial disease, a non atheromatous cause should always be sought for, even if risk factors for atherosclerosis are present.

Adult↗
PubMed2006

Age-dependent changes of airway and lung parenchyma in C57BL/6J mice.

In the current study, we hypothesize that senescent-dependent changes between airway and lung parenchymal tissues of C57BL/6J (B6) mice are not synchronized with respect to altered lung mechanics. Furthermore, aging modifications in elastin fiber and collagen content of the airways and lung parenchyma are remodeling events that differ with time. To test these hypotheses, we performed quasi-static pressure-volume (PV) curves and impedance measurements of the respiratory system in 2-, 20-, and 26-mo-old B6 mice. From the PV curves, the lung volume at 30 cmH(2)O pressure (V(30)) and respiratory system compliance (Crs) were significantly (P < 0.01) increased between 2 and 20 mo of age, representing about 80-84% of the total increase that occurred between 2 and 26 mo of age. Senescent-dependent changes in tissue damping and tissue elastance were analogous to changes in V(30) and Crs; that is, a majority of the parenchymal alterations in the lung mechanics occurred between 2 and 20 mo of age. In contrast, significant decreases in airway resistance (R) occurred between 20 and 26 mo of age; that is, the decrease in R between 2 and 20 mo of age represented only 29% (P > 0.05) of total decrease occurring through 26 mo. Morphometric analysis of the elastic fiber content in lung parenchyma was significantly (P < 0.01) decreased between 2 and 20 mo of age. To the contrary, increased collagen content was significantly delayed until 26 mo of age (P < 0.01, 2 vs. 26 mo). In conclusion, our data demonstrate that senescent-dependent changes in airway and lung tissue mechanics are not synchronized in B6 mice. Moreover, the reduction in elastic fiber content with age is an early lung remodeling event, and the increased collagen content in the lung parenchyma occurs later in senescence.

Aging↗
PubMed1993

The relationship between wall tension, lamellar thickness, and intercellular junctions in the fetal and adult aorta: its relevance to the pathology of dissecting aneurysm.

It is known that the distribution of stress and strain in the vessel wall is not uniform. We believe that this explains the location of the plane of dissection in dissecting aneurysms of large elastic arteries. We have investigated the effects of non-uniformity of stress and strain on the thickness of each elastic lamella and on the distribution of intercellular junctions in the media of developing and adult rats, to seek evidence to support this hypothesis. Intercellular junctions were identified by transmission electron microscopy of whole wall sections. A morphometric study of elastic tissue distribution was made on an image analysis computer. Differences were analysed using one-way analysis of variance. There are between six and eight elastic lamellae in the aorta of rats. In the fetus, only the internal elastic lamella is complete; the others were not fully formed by term. In the adult, the inner five elastic lamellae were thicker than the remaining two or three, and smooth muscle cells in the thicker lamellar units had more cell-cell contacts of all types examined. These data support the concept of a difference in stress-resisting properties of the aortic wall on the junctions between the inner two-thirds and the outer third of the media. The findings indicate that, as proposed in theoretical models the innermost lamellae support the high tension. In the adult aorta, the structure is modified to enhance the capacity to resist stress in the internal two-thirds of the media.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Dissection↗