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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The collagen types extracted from intermediate and small sized human arteries were investigated by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) after differential salt fractionation. Limited and repeated pepsin digestion was used to prepare collagen species. Type V, IV and VI collagens were extracted greater in the former relative to in the latter, whereas type I and III collagen were extracted until the last extract. Type I collagen comprised as the major collagen in the intima of various arteries as well as in venous tissue. Type III and V collagens were found to be less in small arteries than in the initial stage of atherosclerosis. Type VI collagen in the intermediate and small arteries was detected on SDS-PAGE.
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PMID:Collagen species in various sized human arteries and their changes with intimal proliferation. 210 67

The types of collagen components extracted from human aortas by repeated pepsin digestion were investigated by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), after differential salt precipitation, cyanogen bromide (CNBr) cleavage and beta-mercaptoethanol reduction. For further extraction of collagen components, repeated pepsin digestion was carried out, and two extracts, the former and latter, were obtained. The greatest increase was seen in type V collagen followed by type III in the former extract. Type I collagen was continually extracted, so the proportion of type I to other types became greater with the number of extractions. SDS-PAGE of the residue treated with CNBr revealed that it contained the greatest amount of type I, followed by the latter extract. Type I collagen comprised approximately two-thirds of the total collagen. It was the most predominant in the intima and adventitia but was also obviously abundant in the media. The proportion of type III collagen to total collagen fell slightly with advancing atherosclerosis, since the amounts of types I and V showed some increase. A band of the alpha 3(V) chain of type V collagen in the intima was occasionally detected between the bands of the alpha 1(V) and alpha 2(V) chains. Basement membrane collagen, type IV, which was extracted predominantly from the intima and subintima, showed a heterogenous distribution as to molecular size, ranging from 50 Kd to 140 Kd. The alpha 1(IV) and alpha 2(IV) collagens were found at positions corresponding to 100 Kd and 80 Kd, respectively. The content of collagen type IV also increased with the proliferative fibrotic process. Type VI collagen was found in the intima and subintima of the human aorta at a position corresponding to an approximate molecular weight of 150 Kd, and it was reduced to fragments of 40 Kd, 45 Kd and 52 Kd.
Atherosclerosis 1986 Jun
PMID:Collagen types in various layers of the human aorta and their changes with the atherosclerotic process. 308 34

A relationship was assessed between the amino acid composition of 9 protein sources or of their in vitro digestion products and total serum cholesterol in rats. Three animal proteins (casein, beef, fish) and 6 vegetable proteins (soy, pea, peanut meal, rapeseed, oatmeal, wheat gluten) were tested. The intact protein sources were submitted to an enzymatic proteolysis according to a new in vitro digestion method. Each protein source was hydrolyzed for 30 min with pepsin at pH 1.9, then with 10 mg pancreatin at basic pH in a dialysis cell. The digestion products diffused through the dialysis membrane of the cell and were collected by a circulating sodium phosphate buffer over a 6-h period. They were likely to correspond to end products luminal in vivo digestion. The aromatic and the basic amino acids were present in higher proportions in the digestion products than in the intact protein sources, reflecting the specificity of the proteolytic enzymes. Total serum cholesterol was measured on male Sprague-Dawley rats fed cholesterol-free or cholesterol-enriched (1% cholesterol, 0.5% cholic acid) semipurified diets containing protein sources. Total serum cholesterol ranged from 70 mg/dl with the pea diet to 98 mg/dl with the peanut meal diet in rats fed cholesterol-free diets and from 163 mg/dl with the wheat gluten diet to 313 mg/dl with the casein diet in rats fed the cholesterol-enriched diets. These results suggested no specific effect of protein from animal or vegetable origin on total serum cholesterol in rats. In rats fed cholesterol-enriched diets, significant correlations were observed between total serum cholesterol and tyrosine content or leucine/isoleucine ratio of digestion products. These correlations were stronger than those observed with intact protein sources.
Atherosclerosis 1986 Aug
PMID:Relationship between dietary proteins, their in vitro digestion products, and serum cholesterol in rats. 309 37

Collagenous components were extracted from bovine aorta by pepsin digestion. Differential salt precipitations separated the interstitial from the basement membrane (BM) collagens, and the latter were subsequently separated into three distinct types. Ion exchange chromatography, SDS-slab gel electrophoresis, cyanogen bromide and protease V8 peptide mapping, and amino acid analysis were used to characterize the component chains within each of these types. The major BM-class contained three distinct chains which were identical to the alpha 1(V), alpha 2(V) and alpha 3(V) chains of type V collagen from normal human placenta. The stoichiometry of the chains suggests a [alpha 1(V)]2 alpha 2(V)-helical organization, but the role of the alpha 3(V) chain in the overall structural organization of collagen V remains unknown. The second BM-class contained a heterogeneous group of molecules ranging in size from 40 000 to 140 000 daltons. Two predominant chains within this group were characterized as the alpha 1(IV) and alpha 2(IV) chains of type IV collagen. The last class of BM collagens consisted primarily of high molecular weight components; upon reduction these gave rise to two low molecular weight collagenous species (40 K and 45 K) characteristic of type VI, low molecular weight or 'linker' collagens. The functional roles of the isolated BM collagens, either individually or collectively, has not been ascertained to date.
Atherosclerosis 1984 Jan
PMID:Characterization of basement membrane collagens of bovine aortae. 669 80

Estimation of collagens types I and III in pepsin digests and by analysis of specific cyanogen-bromide derived peptides by SDS-polyacrylamide gel electrophoresis, has indicated that both the undiseased human aortic media and the atherosclerotic plaque of the diseased intima contain more type I collagen than type III. There was only a relatively small shift in composition in favour of type I collagen in the diseased compared to the undiseased tissue. Diffusely thickened intima was similar in composition to the atherosclerotic plaque. These results suggest that both atherogenesis and diffuse intimal thickening may involve primarily smooth muscle cell hyperplasia with increased overall collagen production but little alteration in cell phenotype as regards the relative proportions of the individual collagens produced. They do not support the contention that atherosclerosis involves a 'transformation' of smooth muscle cells to fibroblast in type, whereby a major switch in synthesis occurs from largely type III collagen to mainly type I in disease. Type V collagen(s) containing both alpha A- and alpha B-chains has been detected throughout the vessel wall in diffusely thickened intima, media and adventitia, as well as in the plaque where, in the latter case, a marked enrichment relative to interstitial collagens was noted. This is presumed to reflect the relatively cellular nature of the atherosclerotic lesion. The alpha C-chain of type V collagen was detected in porcine but not human aorta.
Atherosclerosis 1982 Mar
PMID:Collagen polymorphism in the normal and diseased blood vessel wall. Investigation of collagens types I, III and V. 708 17

Samples of human Common Iliac Arteries, obtained post-mortem from patients without evidence of atherosclerosis, were analyzed for their content in the various types of collagens using alternatively sonication, pepsin digestion and dithiothreitol reduction followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis of the extracts. A final average proportion of 66% of the total collagen was solubilized. The statistical calculation of the proportions of the different collagens, deduced from the densitometric scannings of the electrophoretic runs, showed that a larger amount of type I was extracted when the extraction was more complete. Type I collagen appeared as the most insoluble collagen in these arteries and its final proportion was probably higher than 60% of the total collagen.
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PMID:An evaluation by sequential extraction of the proportions of collagen types from medium sized arteries. 718 71

Using pulse-label experiments in organ culture, collagen synthesis was studied in aortas from healthy and atherosclerotic specimens. Investigations were carried out on human atherosclerotic plaques as well as in the mini-pig in which atherosclerosis occurred spontaneously, and in the rabbit where atherosclerosis was experimentally induced by cholesterol-enriched feeding. When compared to total protein synthesis, the percentage of newly synthesized collagens measured as radioactive pepsin-resistant material, decreased with age in healthy specimens, whereas it remained at a higher level when the aortas were atherosclerotic. Subsequent molecular sieve chromatography of the radioactivity pepsin-resistant material allowed the separation type I collagen from type III collagen and their relative quantification. The results showed that the newly synthesized type III collagen accounted for 16-31% in aortic explants from young animals, for 30-36% when the explants were derived from older specimens and for 35-48% when the tissues were atherosclerotic.
Atherosclerosis 1981 Apr
PMID:Collagen synthesis in organ culture of normal and atherosclerotic aortas. 724 84

We examined the interactive effect of oxidized low density lipoprotein (LDL) and ascorbic acid on collagen production in cultured smooth muscle cells (SMCs). Porcine aortic SMCs were incubated with 50-200 micrograms/ml of human LDL with/without 5 microM Cu2+ for 24 h. Collagen production was assayed by successive salt precipitation at acidic and neutral pH after pepsin digestion of 3H-proline-labeled collagenous protein. Oxidation of LDL was evaluated by electrophoresis and by the level of thiobarbituric acid reactive substances (TBARS). Ascorbic acid reduced the oxidation of LDL + Cu2+ (53% reduction). In the presence of ascorbic acid, no differences were noted in collagen production between LDL and LDL + Cu2+. Without ascorbic acid, collagen production with LDL + Cu2+ was increased dose-dependently up to 6-fold with 150 micrograms/ml LDL, while no such effects were observed at any doses of native LDL. The addition of butylated hydroxytoluene to LDL + Cu2+ strongly suppressed oxidation (88% reduction), and significantly reduced collagen production close to that seen with native LDL. These results indicate that oxidized LDL stimulates collagen production in SMCs, while native LDL does not. Therefore, oxidized LDL may play a direct role in stimulating collagen production in SMCs, which could lead to collagenosis in atherosclerosis.
Atherosclerosis 1995 Jul
PMID:Oxidized low density lipoprotein stimulates collagen production in cultured arterial smooth muscle cells. 748 30

The relationship between the extractability of collagen by enzymatic digestion and the degree of nonenzymatic glycation of collagen was examined in the aorta and skin from 38 subjects without diabetes mellitus (mean age: 62.3 +/- 20.2 years). Samples were obtained from the aortic media (M), lesion-free intima (I), atherosclerotic intima (A) and dermis of the skin (S). Collagen was extracted first by incubation with 1/50 (enzyme/substrate weight ratio) pepsin at 4 degrees C for 24 h (P-fraction) and then by incubation with 1/10 (enzyme/substrate weight ratio) pepsin at room temperature for 24 h (EP-fraction). The pepsin-insoluble precipitates were digested by incubation with 270 units of bacterial collagenase at 37 degrees C for 24 h (PIS-fraction). Collagen contents, ketoamines and collagen-linked fluorescence (CLF) were measured in each fraction. The amount of ketoamines and the level of CLF correlated inversely with the susceptibility of collagen to pepsin digestion in various tissues, including M, I, A and S. These values were highest in both the P- and EP-fractions of M, which contained the least amount of collagen extracted by pepsin digestion. In contrast, they were lowest in S, where the concentration of collagen extracted by pepsin digestion was greatest among all of the tissue samples. Atherosclerotic intima (A) and aortic media (M) showed an age-related increase in the total amount of collagen digested with pepsin and collagenase, which depended mainly on an increase in the content of pepsin-insoluble collagen. Although the total amount of collagen did not increase with advancing age in I or S, collagen in I and S became progressingly resistant to pepsin digestion. These results suggest that the age-related decrease in the susceptibility of collagen to pepsin digestion may be due to nonenzymatic glycation in atherosclerotic lesions as well as normal tissues, including the aortic media, lesion-free intima and skin. The level of CLF significantly increased with age in the P-fraction and/or EP fraction of M, I and S. However, there was no relationship between the level of CLF and the subject's age in A. Thus, the accumulation of advanced glycation endproducts (AGEs) on collagen fibers may be partially responsible for the increase in collagen matrix in atherosclerotic lesions of subjects without diabetes mellitus.
Atherosclerosis 1995 Jul
PMID:Nonenzymatic glycation and extractability of collagen in human atherosclerotic plaques. 748 34

The idea of a fat transport system in the plasma of mammals evolved slowly over three centuries. At the turn of this century, it was discovered that plasma globulins contained lecithin and that the digestion of plasma proteins with pepsin liberated small amounts of fat and cholesterol. The high density lipoprotein (HDL) was first isolated from horse serum in 1929 and the low density lipoprotein (LDL) in 1950. It was then shown that flotation of plasma in the ultracentrifuge revealed an array of lipoproteins that included VLDL, LDL and HDL and permitted quantitation. Subsequently, it was discovered that the free fatty acids (FFA) in plasma were bound to albumin and varied with feeding and fasting. From further studies, it was concluded that lipoprotein-bound triglycerides were delivered to adipose cells for uptake after meals; during fasting, the fat cells secreted FFA, which provided fuel for many tissues. The protein components of the lipoproteins (apopeptides) were characterized in the period from 1960 to 1970 and the LDL-receptor was identified in 1974. Fat transport was then established as a receptor-mediated delivery system of lipoproteins to targeted tissues. Defects in this system due to genetically altered or absent receptors explained dyslipidemias, which promoted atherosclerosis, xanthomatosis and Alzheimer's disease.
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PMID:Discovery of the lipoproteins, their role in fat transport and their significance as risk factors. 947 44


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