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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The elastic cartilage of the rat epiglottis was studied with a high-resolution SEM technique. The chondrocytes were found to be anchored in their lacunae by fibrils running in from the territorial matrix. This matrix exhibited a dense network of fibrils arranged tangentially around the lacunar cavity. The fibrils of the inter-territorial matrix however, formed a three dimensional network of sheets with interconnecting fibrils. The SEM has shown up for the first time a substructure in the fibrils in the form of circular protuberances arranged circumferentially around the fibrils and forming ridges 12--19 nm apart. We suggest that the fibrils are collagen, and the protuberances are the proteoglycans attached to the collagen fibrils. Globules seen attached to the fibrils are most probably 'matrix granules' as observed in other kinds of cartilage. The total inability to visualize elastin with the high resolution SEM is puzzling.
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PMID:High resolution scanning electron microscopy of elastic cartilage. 57 60

Bundles of collagen fibrils, elastic fibres and fibroblasts are organized into a network that lies in the plane of a large portion of the bat wing. By ultrastructural (TEM and SEM) and biochemical analyses it was found that individual bundles of the net are similar to elastic ligaments. Although elastic fibres predominate, they are integrated and aligned in parallel with small bundles of collagen. A reticulum of fibroblasts, joined by focal junctions, forms a cellular framework throughout each bundle. Because of the unique features of the fibre bundles of the bat's wing, in particular their accessibility, and the parallel alignment of the collagen fibrils and elastic fibres in each easily isolatable fibre bundle, they should prove a most valuable model for connective tissue studies, particularly for the study of collagen-elastin interactions.
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PMID:A collagen and elastic network in the wing of the bat. 64

Chronic pulmonary hypertension is associated with arterial structural remodeling. Insulin-like growth factor I (IGF-I) has been proposed as one of the mediators of vascular change because of its ability to stimulate proliferation in, and elastin production by, cultured vascular smooth muscle cells. We have shown previously that 12 days of continuous air embolization into the pulmonary arterial circulation of sheep results in the functional and structural changes of chronic pulmonary hypertension. In the present study, measurements of IGF-I (by radioimmunoassay) and IGF-I binding protein activity in sheep lung lymph and plasma were made before and during the 12 days of air embolization in six sheep. Two untreated animals served as controls. Baseline lung lymph contained 23.5 +/- 3.6 ng/ml (mean +/- SEM) of IGF-I, and there was a slight increase to 36.7 +/- 9.8 on day 3, but by day 6 levels were back to baseline. The flux of IGF-I from the lung (concentration times lymph flow) increased significantly by day 2 embolization and remained elevated through day 12 (baseline = 37.2 +/- 11.1 ng/15 min; day 2 = 237.7 +/- 55.8; day 5 = 190.2 +/- 53.4; day 6 = 82.6 +/- 21.9; day 12 = 78.7 +/- 12.5). IGF-I binding protein activity was also present in lung lymph at baseline (29.6 +/- 3.0%) and was unchanged during air embolization. Plasma levels of IGF-I and plasma binding protein activity remained at baseline throughout the 12 days of embolization (71.51 +/- 34.48 ng/ml and 36.4 +/- 3.5%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Insulin-like growth factor I and pulmonary hypertension induced by continuous air embolization in sheep. 172 99

Treatment of chronic hypertension with cilazapril, but not hydralazine, attenuates changes in distensibility of cerebral arterioles that occur in stroke-prone spontaneously hypertensive rats (SHRSPs). In this study, effects of antihypertensive treatment on composition of cerebral arterioles was determined in SHRSPs. Cilazapril (45 mg/kg/day), an angiotensin converting enzyme (ACE) inhibitor, or hydralazine (18 mg/kg/day) was begun when rats were 3 months of age. Both cilazapril and hydralazine reduced systolic arterial pressure in SHRSPs (from 199 +/- 6 to 122 +/- 7 mm Hg for cilazapril versus 143 +/- 5 mm Hg for hydralazine [mean +/- SEM]; p less than 0.05). Cerebral arterioles were fixed in vivo, and the cross-sectional area of the vessel wall was measured histologically. In SHRSPs, both cilazapril and hydralazine reduced cross-sectional area of the vessel wall to values obtained in Wistar-Kyoto (WKY) rats. Thus, both cilazapril and hydralazine prevented hypertrophy of cerebral arterioles in SHRSPs. Composition of the arteriolar wall was determined with point counting stereology. Cerebral arterioles in SHRSPs contained significantly more smooth muscle and elastin than in WKY rats (1,294 +/- 157 versus 853 +/- 88 microns2, respectively, for smooth muscle and 148 +/- 13 versus 108 +/- 7 microns2, respectively, for elastin (120 +/- 8 microns2) in cerebral arterioles in SHRSPs was similar to that in WKY rats. Treatment with hydralazine was effective in preventing increases in elastin (128 +/- 14 microns2) and in attenuating increases in smooth muscle (1,008 +/- 18 microns2). The ratio of nondistensible (collagen, basement membrane) to distensible (smooth muscle, elastin, endothelium) components was greater in SHRSPs than in WKY rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of antihypertensive treatment on composition of cerebral arterioles. 183 21

The accuracy of methods employed to measure the elastin-specific crosslinks, desmosine (DES) and isodesmosine (IDES), has been called into question because contaminants in the urine may cause elevated values. In the present study urine samples were spiked with a known amount of [14C]DES and refluxed in 6 N HCl. Sephadex G-15 chromatography of the hydrolyzed urine employed to remove contaminants. DES and IDES were quantified by high performance liquid chromatography (HPLC) as well as by amino acid analysis. The amount of isotope recovered was used to determine losses during the overall procedure and the isotope dilution to calculate the amounts of endogenous DES and IDES originally present in the urine. Because similar values were obtained by both methods, the more rapid HPLC method was used for all succeeding analyses. In one experiment, the DES amounts in urine collected from hamsters for 3 days after intratracheal treatment with human neutrophil elastase (300 micrograms) or porcine pancreatic elastase (300 micrograms) were 0.212 +/- 0.012 (mean +/- SEM, two measurements on a single pool) and 0.816 +/- 0.005 (two measurements) microgram per hamster per day, respectively. Urine from control hamsters had a mean value of 0.074 +/- 0.008 (eight measurements) microgram per hamster per day. The HNE- and PPE-treated hamsters had mean linear intercept values of 119 and 159% of control values, respectively, giving a positive correlation between increase in airspace size and elevation of urinary DES.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Measurement of urinary desmosine by isotope dilution and high performance liquid chromatography. Correlation between elastase-induced air-space enlargement in the hamster and elevation of urinary desmosine. 185 49

Although the artery wall consists of three distinct layers, only the structures of the intima and media have been well characterized. The adventitia has generally been overlooked. Our examination focused on the organization of elastin and collagen which are the major components of this tunic. Canine infrarenal aortas were excised, stretched to their in vivo length, then pressure fixed in formalin. Transverse, longitudinal, and frontal sections were prepared with specific elastin and collagen stains. Areas of adventitia in these sections were examined with LM, and interconnections between collagen and elastin were photographed at various magnifications. Subsequently, the slides were fractured for attachment to SEM stubs, and the coverslips were demounted. The identical areas were then examined with SEM using the LM micrographs as a guide to identify elastin and collagen. Whole mount aortic ring preparations were digested in formic acid for 72 and 96 h at 45 degrees C to confirm adventitial elastin architecture. The adventitia was organized in alternating lamellae of collagen and elastin. The elastin lamellae consisted of continuous sheets of elastin with a longitudinal fibrillar substructure. Finer circumferential elastin fibers were also identified. These attached to both longitudinal elastin and adjacent collagen lamellae. Collagen lamellae were arranged in broad corrugated bands of fibrils. The unique architecture of the adventitia may explain some of the visco-elastic properties of the aorta in both normal and pathologic states.
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PMID:The architecture of adventitial elastin in the canine infrarenal aorta. 206 31

We have developed an acellular matrix vascular prosthesis (AMVP) made by detergent and enzymatic extraction of natural arteries, yielding a tissue framework of collagen and elastin from the original vessel, with preservation of the natural basement membrane at the blood flow surface. These biografts have excellent handling characteristics and suturability, as well as low thromboreactivity. Whole vessel static testing of circumferential compliance (8.9 +/- 1 [SEM] X 10(-2)% mmHg at 100 mmHg) revealed behavior virtually identical to the paired natural vessel from which each AMVP was derived in nine canine carotid arteries. We implanted 16 canine-origin AMVPs into nine dogs (12 femoral and three carotid arteries, and one infrarenal aorta) with no antithrombotic drugs. Angiographic patency was maintained in 15 of 16 (one occlusion within 3 days) for follow-up from 3 days to 6 years, with no aneurysm formation in three AMVP at over 4 1/2 years. Explant analysis revealed preservation of AMVP elastica and collagen with no inflammation or dystropic calcification of the AMVP, and almost total thrombus free flow surfaces. These results suggest that allograft AMVPs could achieve long-term patency equivalent to saphenous veins.
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PMID:Acellular matrix allograft small caliber vascular prostheses. 225 93

The purpose of this study was to examine effects of aging on the mechanics and composition of cerebral arterioles. We measured pressure (servo-null) and diameter in pial arterioles in anesthetized adult (9-12 months old) and aged (24-27 months old) Fischer 344 rats. After deactivation of smooth muscle with EDTA, diameter of pial arterioles at 70 mm Hg pial arteriolar pressure was less in aged than in adult rats (67 +/- 4 vs. 81 +/- 4 microns [mean +/- SEM], p less than 0.05). The stress-strain relation and the slope of tangential elastic modulus versus stress (6.8 +/- 0.6 vs. 5.3 +/- 0.3, p less than 0.05) indicated that distensibility of pial arterioles was reduced in aged rats. Cross-sectional area of the vessel wall, measured histologically, was less in aged than adult rats (1,239 +/- 91 vs. 1,832 +/- 180 microns2, p less than 0.05). Point counting stereology was used to quantitate smooth muscle, elastin, collagen, and basement membrane in the arteriolar wall. Cross-sectional areas of smooth muscle and elastin were significantly less in aged than adult rats (744 +/- 57 vs. 1,291 +/- 119 microns2 for smooth muscle, 52 +/- 6 vs. 113 +/- 15 microns2 for elastin; p less than 0.05), whereas cross-sectional areas of collagen and basement membrane were not significantly different in aged and adult rats (4 +/- 1 vs. 3 +/- 1 microns2 for collagen, 236 +/- 17 vs. 258 +/- 31 microns2 for basement membrane). The ratio of nondistensible (collagen and basement membrane) to distensible (smooth muscle and elastin) components was greater in aged than adult rats (0.30 +/- 0.01 vs. 0.18 +/- 0.01, p less than 0.05). Thus, we conclude that, during aging, cerebral arterioles undergo atrophy, distensibility of cerebral arterioles is reduced, and the relative proportion of distensible elements, elastin and smooth muscle, is reduced in the arteriolar wall.
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PMID:Effects of aging on mechanics and composition of cerebral arterioles in rats. 234 72

Light microscopy of the mandibular joint tissues from fetal mice show a distribution of fibrillar structures in the articular fibrous capsule covering the condylar head. Further SEM and TEM studies were conducted on autoclaved xiphoid and mandibular condylar processes of the fetuses for observation of the elastic system fibers in these cartilaginous tissues. SEM showed that non-collaginous fibers branched and united to form a complicated network in the cartilage. A fine structure study on diameter distribution of the fibers indicated elastogenesis in the differentiating cell layer and fiber maturation in the articular surfaces and calcification layer, thus suggesting a sequential development, growth, and degeneration of the cellular and fibrillar components in the cartilage, as well as bidirectional cell differentiation in the growing mandibular joint. A further TEM study on these autoclaved connective tissues showed the elastic system fibers in the network to be composed of fine microfibrils and amorphous elastin. The elastic fibers in the condylar cartilage were a loose network having many tortuous main and oblique elastic fibers, and coiling oxytalan fibers.
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PMID:Fine structure of cartilage elastic system fibers, in particular those of the mandibular condyle. 264 Sep 43

Physiologic stimuli of connective tissue accumulation in pulmonary vascular remodeling are poorly defined. We postulated that increased pressure within central pulmonary arteries is a stimulus for connective tissue synthesis and the response is dependent on an intact endothelium. Mechanical tension equivalent to 50 mmHg pressure was applied for 4 h to isolated rat main pulmonary arteries (endothelium intact or removed), and incorporation of [14C]proline into collagen, [14C]valine into elastin, [3H]thymidine into DNA and pro alpha 1 (I) collagen mRNA levels were measured. In intact vessels, tension induced synthesis of collagen (3.1 +/- 0.4 vs. 2.3 +/- 0.5 [SEM] dpm X 10(2) [14C]-hydroxyproline/[mg protein.h]) (n = 10) and elastin (6.1 +/- 2.4 vs. 2.9 +/- 0.4 dpm X 10(3) [14C]valine/[mg protein.h]) (n = 5) (both P less than 0.05). Steady state mRNA levels of pro alpha 1 (I) collagen were also increased by tension (46 vs. 30 X 10(2) dpm hybridized/100 ng total RNA). However, the stimulus did not increase [3H]thymidine incorporation into DNA. In denuded vessels, tension had no effect on connective tissue synthesis or mRNA level of pro alpha 1 (I) collagen. Messenger RNA levels for v-sis were induced by tension in intact but not denuded vessels. Our findings establish that induction of vascular connective tissue synthesis by mechanical tension is dependent on an intact endothelium.
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PMID:Pressure-induced connective tissue synthesis in pulmonary artery segments is dependent on intact endothelium. 266 38


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