Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Early atherosclerotic lesions in human aortas less than five hours postmortem were studied by light microscopy (20 cases) and electron microscopy (10 cases), to determine the morphological and cytochemical character of calcium deposition in the lesions. Routine and multiple special stains by light microscopy demonstrated atherosclerotic (intimal) calcium to be deposited as fine grains, ring-shaped droplets or small needle-shaped crystals, and medial calcium as fine grains or ring-shaped droplets. The calcium deposits were frequently associated with the PAS-positive basal lamina surrounding smooth muscle cells. In the intimal lesions the calcium deposits were often associated with fine granular lipid, while this association was much less frequent in the media. Calcium in atherosclerotic intima was generally not closely associated with elastic fibers but in the media was often deposited along or near elastic fibers. By electron microscopy the atherosclerotic lesions were composed of many smooth muscle cells (with or without lipid droplets), newly formed elastic fibers, amorphous ground substance, a few collagen fibrils and many membrane-limited matrix vesicle-like structures, 100-700 nm diameter. Many similar vesicles were present between the elastic laminae of the media. With the potassium pyroantimonate technique for demonstrating calcium, reaction products were most concentrated within these matrix vesicles but were also present in mitochondria of smooth muscle cells, within extracellular mitochondria-like structures, in pericellular basal lamina-like material and loosely dispersed in the interstitial ground substance. All elastic fibers were negative for calcium by this technique. The membrane of the matrix vesicle-like structures were cytochemically positive for alkaline phosphatase and adenosine triphosphatase. These studies suggest that calcification in human atherosclerosis and media is related to smooth muscle cell degeneration and that the major initial loci for calcium deposition are matrix vesicles from degraded cells, comparable to osteogenic calcification of cartilage.
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PMID:Calcification in atherosclerosis. I. Human studies. 294 18

For comparison with our previous study on early calcification in human atherosclerosis, the aortas of rabbits and chickens with experimentally induced atherosclerosis were studied by gross examination, light microscopy and electron microscopy, including various cytochemical techniques. Nine male New Zealand white rabbits and nine male white leghorn chickens were fed an atherogenic diet of chow with 8% peanut oil and 2% cholesterol for one, two or three months. Six rabbits and six chickens, fed normal chow for one, two or three months, served as controls. The normal diet chickens were found to have lipid-negative spontaneous fibrous plaques in the abdominal aorta, which following atherogenic diet developed lipid deposition and increasing calcium deposition. The normal diet rabbits had no aortic lesions, but following an atherogenic diet developed highly lipid-positive foam cell intimal lesions which subsequently developed increasing amounts of smooth muscle cells and calcium. Ultrastructurally, the aortic plaques in normal diet chickens were composed of smooth muscle cells, collagen, elastic fibers, ground substance and a few small extracellular matrix vesicles bounded by a trilaminar membrane. In the atherogenic diet chickens, these vesicles increased in number as did their staining for calcium by the pyroantimonate technique. The membranes of vesicles were cytochemically positive for alkaline phosphatase and adenosine triphosphatase. Similar matrix vesicles were present in the interstitium of the media. In both intima and media, the vesicles appeared to be largely derived from degenerating smooth muscle cells. The aortas of atherogenic diet rabbits were similar to the chickens except for many more lipid-laden foam cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcification in atherosclerosis. II. Animal studies. 378 82

A light microscopy study on the localization of enzyme activity within atherosclerotic human intracranial arteries was performed on autopsy material obtained within 4 hours of death. The data suggests that the atherosclerotic process first goes through a proliferative phase and then a degenerative phase culminating in the formation of a plaque. In the proliferative phase, smooth muscle cell proliferation has formed a thickened intima. Tetrazolium reductase, adenosine triphosphatase (ATPase) and adenosine monophosphatase (AMPase) activities are present in these cells, while all dehydrogenases and acid phosphatase activities were weak or not present. As the degenerative phase commences, an area of necrosis, lipid and macrophage accumulation is formed on the lumen side of the elastica. This area increases in size until a plaque is formed. Unsaturated polar and nonpolar lipid, cholesterol, alpha-glycerophosphate dehydrogenase, acid phosphatase, and AMPase activities are associated with these areas and in foam cells, which are often found in the thickened intima of the proliferative phase. Tetrazolium reductase and ATPase activities decrease in the thickened intima as the area of necrosis increases in size, while dehydrogenase activity, except that for alpha-glycerophosphate, remains low or not present. Patterns of enzyme alterations for various stages of the disease process in intracranial arteries, the aorta and coronary arteries suggest a similar, if not identical, progression of the atherosclerotic process, irrespective of known differences in the prevalence of atherosclerosis.
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PMID:A histoenzymatic study of human intracranial atherosclerosis. 426 Jul 21

Parallel stereo- and cytospectrophotometric examinations of human myocardial capillaries, 20-60 min after biological death were carried out. The activity of alkaline phosphatase, adenosine triphosphatase, lactate dehydrogenase and NAD-diaphorase in the capillary wall in relation to the sex and age in cardiovascular pathology, renal diseases and leukemias were studied. The permeability and level of energy supply of transendothelial transport were found to depend on the kind of the main pathological process and type of death. According to the parameters under study, the functional state of the capillary network of the myocardium in atherosclerosis with or without its combination with hypertension and also in secondary renal hypertension is described.
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PMID:[Stereological characteristics and enzymatic activity of myocardial capillaries in different variants of pathology and death (data from immediate autopsies)]. 686 Jan 68

The cells within the vascular wall act as a unit regulating the contraction of smooth muscle cells. In arteries the endothelium and autonomic nerves provide the major factors that regulate intracellular calcium in smooth muscle cells, which determines contractile tone. The endothelium provides a major inhibitory influence, which itself is modulated by shear forces within the vascular lumen regulating endothelial cell calcium and the release of endothelium-derived relaxing factors. Of the major mechanisms controlling smooth muscle calcium, it has been suggested that voltage-dependent calcium channels are among the most important in mediating the inhibitory influence of the endothelium. Smooth muscle potassium channels and sodium-potassium adenosine triphosphatase (Na+,K(+)-ATPase) are important regulators of membrane potential, and each is affected by the endothelium. Because the activity of each hyperpolarizes the membrane potential, they counter the influence on voltage-dependent calcium channels and inhibit contraction. Both of these counterregulatory mechanisms have recently been shown to be impaired in diseased arteries. This may help to explain the diminished effectiveness of the endothelium on the smooth muscle. Thus, vascular disease may cause diminished release, increased destruction, or limited effectiveness of endothelium-derived relaxing factors. The failure of the inhibitory influence of the endothelium may be the principal mechanism by which vascular risk factors and disease increase vasoconstrictor tone, possibly contributing to hypertension and the progression of atherosclerosis.
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PMID:Pathways controlling healthy and diseased arterial smooth muscle. 837

In the present work we studied in vitro the action of low density lipoproteins (LDL) isolated from normolipemic insulin-dependent diabetic (IDDM) patients on transmembrane cation transport, nitric oxide synthase (NOS) activity, and aggregating response to stimuli of platelets from healthy subjects to elucidate whether the modified interaction between circulating lipoproteins and cells might be one of the pathogenetic mechanisms of the increased platelet activation in IDDM. LDL were obtained by discontinuous gradient ultracentrifugation from 15 IDDM out-patients and 15 sex- and age-matched healthy subjects and used for incubation experiments with control platelets. Lipid composition and hydroperoxide concentrations were studied in LDL. Platelet aggregation responses to ADP, NOS activity, cytosolic Ca2+ concentrations, and platelet membrane Na+/K+-adenosine triphosphatase (Na+/K+-ATPase) and Ca2+-ATPase activities were measured after incubation. IDDM LDL showed an increased lysophosphatidylcholine content compared with that of control LDL. IDDM LDL significantly increased the platelet aggregating response to ADP, cytosolic Ca2+ concentrations, and plasma membrane Ca2+-ATPase activity and significantly reduced NOS activity and platelet membrane Na+/K+-ATPase activity compared with those of platelets incubated in buffer or cells incubated with control LDL. The effects exerted by IDDM LDL on platelet suspensions from healthy subjects mimic the alterations observed in platelets from diabetic subjects in basal conditions. Both the decreased activity of NOS and the higher cytoplasmic concentrations of Ca2+ might cause increased platelet activation, as observed in IDDM. In conclusion, the present study suggests a new mechanism with a potential role in the early development of atherosclerosis in diabetic patients, i.e. an altered interaction between circulating lipoproteins and platelets.
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PMID:Influence of low density lipoprotein from insulin-dependent diabetic patients on platelet functions. 1052 28

Vascular remodeling is a key feature of many pathologic states, including atherosclerosis, or hypertension. Vascular smooth muscle cells participate in determining the vessel structure by several mechanisms such as cell migration, cell growth, or cell death (necrosis or apoptosis). Here we report that thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ -adenosine triphosphatase (ATPase), is able to induce apoptosis in human vascular smooth muscle cells (HVSMCs). Apoptosis was assessed by three different methods: differential chromatin binding dye staining. cytoplasmic histone-associated DNA fragments detection by enzyme-linked immunosorbent assay (ELISA) and terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). When HVSMCs were treated for 1 h with thapsigargin (100 nM-10 microM), there was a concentration-dependent increase in both parameters 24 h after the thapsigargin pulse. When a time-course experiment was performed, both parameters were significantly enhanced from 3 to 6 h after the exposure to thapsigargin. We conclude that thapsigargin promotes apoptosis in HVSMCs, providing a useful tool for the study of programmed cell death in human vascular smooth muscle.
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PMID:Thapsigargin induces apoptosis in cultured human aortic smooth muscle cells. 1106 29

The interaction between low density lipoproteins (LDL) and platelets might play a central role in the development of atherosclerosis in diabetes. The aim of the present study was to investigate whether the glycation of LDL is associated with modifications of their physico-chemical and functional properties and to study the action of glycated LDL (glycLDL) on platelets. LDL and platelets were isolated from 15 healthy subjects. The content of thiobarbituric acid-reactive substances and the generalized polarization of the fluorescent probe Laurdan were determined in LDL glycated in vitro. Platelets were incubated with native LDL, GlycLDL, and minimally oxidized LDL, and the following parameters were evaluated: platelet aggregation, nitric oxide production, intracellular Ca(2+) concentrations, Na(+)/K(+)-adenosine triphosphatase (Na(+)/K(+)-ATPase), and Ca(2+)-ATPase activities. GlycLDL showed increased thiobarbituric acid-reactive substance levels, a red shift of the Laurdan emission maximum, and a decrease in generalized polarization, indicating a higher polarity and a reduced molecular order compared with native LDL. GlycLDL caused a significant increase in platelet nitric oxide production, intracellular Ca(2+) concentration, and aggregating response to ADP; an inhibition of the platelet membrane Na(+)/K(+)-ATPase activity; and a stimulation of Ca(2+)-ATPase activity. Minimally oxidized LDL did not cause statistically significant changes in the parameters studied. The present work demonstrates that glycation induces compositional and structural changes in LDL and suggests that an altered interaction between glycLDL and platelets might play a role in the vascular complications of diabetes.
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PMID:Glycated low density lipoproteins modify platelet properties: a compositional and functional study. 1199 61

Matrix vesicles (MVs) are extracellular, 100 nM in diameter, membrane-invested particles selectively located at sites of initial calcification in cartilage, bone, and predentin. The first crystals of apatitic bone mineral are formed within MVs close to the inner surfaces of their investing membranes. Matrix vesicle biogenesis occurs by polarized budding and pinching-off of vesicles from specific regions of the outer plasma membranes of differentiating growth plate chondrocytes, osteoblasts, and odontoblasts. Polarized release of MVs into selected areas of developing matrix determines the nonrandom distribution of calcification. Initiation of the first mineral crystals, within MVs (phase 1), is augmented by the activity of MV phosphatases (eg, alkaline phosphatase, adenosine triphosphatase and pyrophosphatase) plus calcium-binding molecules (eg, annexin I and phosphatidyl serine), all of which are concentrated in or near the MV membrane. Phase 2 of biologic mineralization begins with crystal release through the MV membrane, exposing preformed hydroxyapatite crystals to the extracellular fluid. The extracellular fluid normally contains sufficient Ca2+ and PO4(3-) to support continuous crystal proliferation, with preformed crystals serving as nuclei (templates) for the formation of new crystals by a process of homologous nucleation. In diseases such as osteoarthritis, crystal deposition arthritis, and atherosclerosis, MVs initiate pathologic calcification, which, in turn, augments disease progression.
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PMID:Matrix vesicles and calcification. 1274 15

Cardiovascular disease, including atherosclerosis, is the leading cause of death in patients with diabetes worldwide; thus, it is a major medical concern. The endothelium contributes to the control of many vascular functions, and clinical observations show that it is a primary target for diabetic syndrome. To get better insight into the mechanisms underlying atherosclerosis, we studied the interspecific differences in the arterial metabolisms of two, Psammomys obesus and Gerbillus gerbillus, as well as Rattus norvegicus (Wistar rat), well known for its atheroresistance. Twenty-two enzymatic activities and six macromolecular substances were histochemically compared in the two desert species and in Wistar aortas (abdominal and thoracic) and arteries (femoral and caudal) embedded in a common block. In the healthy adult rodents, enzyme activities were very intense. They demonstrated that aortic myocytes are capable of various synthesis and catabolism processes. However, considering the frequency of atherosclerosis and its phenotypes, significant differences appeared between the species studied. Our comparative study shows that aortic atherosensitive animals have several common metabolic characteristics, which are found in Psammomys rich in metachromatic glycosaminoglycans (involved in the inhibition of lipolysis and in calcification of the organic matrix), reduced activity in enzymes related to the Krebs cycle (weakening energetic power), and low lipolytic enzyme, adenosine triphosphatase, and adenosine diphosphatase activities. However, the most fundamental pathophysiological difference is the low lipolytic power of the aorta of Psammomys when compared to Wistar rats. This characteristic determines its atherosensitivity and makes this animal model more applicable to the experimental development of atherosclerosis.
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PMID:Atherosclerosis and atherosensitivity in two southwest Algerian desert rodents, Psammomys obesus and Gerbillus gerbillus, and in Rattus norvegicus. 2305 58


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