Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Macrophages and monocytes have essential roles in normal wound healing, in the immune response, and in the pathogenesis of atherosclerosis. Platelet-derived growth factor (PDGF) stimulates the transcription of the early response gene, JE, and its human homolog, macrophage chemotactic protein-1 (MCP-1) in fibroblasts. JE/MCP-1 encodes a cytokine which is a member of a superfamily of small inducible genes that include platelet factor 4, beta-thromboglobulin, 310-C/NAP-1/IL-8, IP-10, KC/gro/MGSA, and others which may play important roles in the inflammatory and immune response. We now report that glucocorticoids inhibit the transcriptional induction of the JE gene by PDGF and serum in a dose-dependent manner. The glucocorticoid response followed the expected anti-inflammatory rank order of potency and was not due to a shift in the time course of induction. Nonsteroidal anti-inflammatory agents were ineffective in reducing JE mRNA levels. Dexamethasone inhibited the accumulation of JE transcripts induced by PDGF, 12-O-tetradecanoylphorbol-13-acetate, and double-stranded synthetic RNA. Nuclear runoff assays demonstrated that the negative regulation occurred by decreasing the transcriptional induction of the JE gene. No effects on JE message stability could be detected in the presence of dexamethasone. The protein synthesis inhibitors cycloheximide and puromycin reversed the glucocorticoid-mediated inhibition and suggested that new protein synthesis was necessary. These results suggest that the transcriptional inhibition of glucocorticoids is mediated by the expression of a labile transcriptional repressor for the JE gene.
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PMID:Glucocorticoids inhibit the transcriptional induction of JE, a platelet-derived growth factor-inducible gene. 171 76

We studied the effects of insulin, glucagon or dexamethasone on the production of apolipoprotein A-IV (apo A-IV) by cultured rat hepatocytes, using specific radioimmunoassay for rat apo A-IV. We also compared the effect of these hormones on the production of apo A-IV with those of albumin and apo A-I, reported previously. In the absence of hormones, apo A-IV and albumin in culture medium increased almost linearly for periods up to 24 h. The rates of accumulation of apo A-IV and albumin in the medium were 15.4 ng/mg cell protein per h and 1.2 micrograms/mg cell protein per h, respectively. The concentration of intracellular apo A-IV remained constant during the incubation. Insulin stimulated the production of albumin, but inhibited the production of apo A-IV dose-dependently. Glucagon inhibited the production of both albumin, and apo A-IV dose-dependently. Dexamethasone showed no significant effects on albumin production, but stimulated apo A-IV production. Thus, apo A-IV production in hepatocytes is regulated by several hormones with different effects on albumin production. The regulatory effects of these hormones on apo A-IV production were almost identical with the effects observed in a course of apo A-I synthesis, suggesting that the production of the two apoproteins are regulated by similar mechanisms.
Atherosclerosis 1991 Apr
PMID:Effect of insulin, glucagon or dexamethasone on the production of apolipoprotein A-IV in cultured rat hepatocytes. 185 65

The effects of dexamethasone (a synthetic glucocorticoid) and insulin on the secretion of very-low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) were investigated. Rat hepatocytes in monolayer culture were preincubated for 15 h in the presence or absence of combinations of 100 nM-dexamethasone and 2 nM-, 10 nM- or 50 nM-insulin. Dexamethasone increased [3H]oleate incorporation into secreted triacylglycerol by 2.7-fold and the mass of triacylglycerol secreted by 1.5-fold. Insulin alone decreased these parameters and antagonized the effect of dexamethasone. Dexamethasone increased the secretion of [3H]leucine in apolipoprotein (apo) E, and in the large (BH) and small (BI) forms of apo B in VLDL by about 7.1-, 3.6- and 4.0-fold respectively. Insulin alone decreased the secretion of these 3H-labelled apolipoproteins in VLDL. However, 2 nM-insulin with dexamethasone increased the secretion of 3H-labelled apo BH and apo BL by a further 0.8- and 3.2-fold respectively; 50 nM-insulin decreased the secretions of apo E, apo BH and apo BL in VLDL. Similar effects for dexamethasone or insulin alone were also obtained for the masses of apo E and apo BL + H secreted in VLDL. Albumin secretion was not significantly altered by either dexamethasone or insulin alone, but in combination they stimulated by 2.1-2.6-fold. Insulin or dexamethasone alone had little effect on the secretion of apolipoproteins in the HDL fraction. However, dexamethasone plus 2 nM-insulin increased the incorporation of [3H]leucine into apo AI, apo AH plus apo C, apo AIV and apo E of HDL by about 1.8-, 1.6-, 1.7- and 2.0-fold respectively. The apo E in the bottom fraction represented about 69% of the total 3H-labelled apo E secreted. The responses in the total secretion of apo E from the hepatocytes resembled those seen in HDL. The interactions of insulin and dexamethasone are discussed in relation to the general regulation of lipoprotein metabolism, the development of hyperlipidaemias and the predisposition to premature atherosclerosis.
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PMID:Stimulation of apolipoprotein secretion in very-low-density and high-density lipoproteins from cultured rat hepatocytes by dexamethasone. 224 66

Cultured rat hepatocytes were used to study the effects of hormones on the production of apo A-I. In addition, we compared these effects with the production of albumin. Hepatocytes were isolated from normal adult rat livers and cultured in MEM, as nearly confluent monolayers. In the absence of hormones, apo A-I and albumin accumulated in the culture medium almost linearly for periods up to 24 h. The rates of accumulation of apo A-I and albumin in the medium were 22 ng/mg cell protein per h and 1.2 micrograms/mg cell protein per h, respectively. During the incubations the cellular contents of apo A-I remained constant. Insulin stimulated the production of albumin at concentrations over 10(-10) M, but inhibited the production of apo A-I at concentrations over 10(-8) M. Dexamethasone showed no significant effects on albumin production but stimulated apo A-I production at concentrations over 10(-6) M. Glucagon inhibited the production of albumin and apo A-I dose-dependently at concentrations over 10(-10) M. Thus, the production of albumin and apo A-I are presumably controlled by different regulatory mechanisms.
Atherosclerosis 1988 Apr
PMID:Effects of insulin, dexamethasone and glucagon on the production of apolipoprotein A-I in cultured rat hepatocytes. 313 65

Cuff-treatment of the rabbit carotid artery produced a diffuse intimal thickening which resembled early lesions of atherosclerosis. A limited amount of focal endothelial damage occurred first (0.5 h), leukocytes infiltrated the subendothelium and extensive endothelial denudation occurred at 24 h. At 3 days, the regenerating endothelium covered the denuded area, and the media was edematous. At 7 days proliferation of intimal cells became visible. Maximum intimal thickening occurred at 3 weeks. Daily injection of dexamethasone (0.01-10 mg/kg i.m.) and ticlopidine (1-100 mg/kg i.m.) dose-dependently attenuated the intimal thickening. Indomethacin had little effect. Inflammatory exudate from zymosan-activated air pouch induced chemotaxis of rat smooth muscle cells (SMC) in vitro. Similar chemotactic activity was observed with leukotriene B4 (LTB4) but not with the other lipoxygenase products tested. The exudate contained reasonable amounts of LTB4, which would account for its chemotactic activity. Dexamethasone inhibited the chemotaxis by the exudate and proliferation of SMC. These results are discussed in relation to the mechanism of atherogenesis. It is concluded that leukocytes play a major role in cuff-induced intimal thickening, and that their products cause endothelial denudation and SMC chemotaxis. Involvement of platelet aggregation in atherogenesis is also suggested.
Atherosclerosis 1987 Apr
PMID:Inflammatory responses in cuff-induced atherosclerosis in rabbits. 360 22

Effect of dexamethasone administration on aortic morphology, cholesterol content and synthesis of prostaglandins from (14C)-arachidonic acid in aorta of spontaneously atherosclerosis susceptible pigeons was examined. Dexamethasone markedly inhibited the synthesis of prostaglandin E2 and stimulated the synthesis of prostaglandin I2 in aorta. In aorta of glucocortocoid treated animals, endothelial abnormalities noted in control birds were decreased and numerous surface protrusions or 'microvilli' were noted. The possibility that glucocorticoid induced inhibition of PGE2 synthesis in pigeon aorta may contribute to improved aortic morphology is discussed.
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PMID:Effect of glucocorticoid administration early in life on aortic prostaglandin synthesis and morphology in atherosclerosis-susceptible pigeons. 392 21

It is well-known that atherosclerotic change and hypertension are common manifestations in patients with glucocorticoid excess. We previously reported that pituitary adenylate cyclase activating polypeptide (PACAP), prostaglandin E2 (PGE2) and carbacyclin, a stable analog of prostacyclin, have suppressive effects on vasopressin-induced DNA synthesis of rat aortic smooth muscle cells through cAMP production (Murase et al., J. Hypertens., 10 (1992) 1505; Oiso et al., Biochem. Cell. Biol., 71 (1993) 156). In the present study, we investigated the effect of glucocorticoid on cAMP production induced by PACAP, PGE2 and carbacyclin in aortic smooth muscle cells. The pretreatment with dexamethasone significantly inhibited cAMP accumulation induced by these vasoactive agents in a dose dependent manner in the range between 10 pM and 10 nM. These inhibitory effects of dexamethasone were dependent on the time of pretreatment up to 8 h. Dexamethasone inhibited cAMP accumulation induced by NaF, a GTP-binding protein activator, and forskolin which directly activates adenylate cyclase. Moreover, forskolin-induced adenylate cyclase activity was significantly reduced in membranes prepared from the cells treated with dexamethasone. These results strongly suggest that glucocorticoid inhibits cAMP production induced by vasoactive agents in primary cultured rat aortic smooth muscle cells and the inhibitory effect is exerted at the level of adenylate cyclase.
Atherosclerosis 1994 Sep 30
PMID:Glucocorticoid inhibits cAMP production induced by vasoactive agents in aortic smooth muscle cells. 785 72

Macrophage apo E synthesis and secretion has been previously demonstrated to be regulated by intracellular free cholesterol levels and is decreased by cytokines and other inflammatory stimuli associated with macrophage activation. In a recent study, the opposing effects of TGF beta and GM-CSF were reported with the former increasing and the latter decreasing apo E secretion and apo E mRNA levels. In an attempt to further understand the mechanisms by which TGF beta increased apo E expression in mouse peritoneal macrophages, the present study was performed to determine whether pharmacological agents could up-regulate apo E secretion by a mechanism independent of intracellular free cholesterol levels. Agents which resulted in increased apo E secretion were subdivided based on their effects on cAMP elevation. In addition to TGF beta, dexamethasone resulted in significant increases in apo E secretion. The 2-4-fold enhancement in apo E secretion by both TGF beta and dexamethasone occurred without concomitant changes in intracellular cAMP or free cholesterol. Other agents which increased apo E secretion included cholera toxin and 8-bromo-cAMP. While these agents did not affect intracellular cholesterol levels, cholera toxin did increase macrophage cAMP. The changes in apo E secretion by dexamethasone and 8-bromo-cAMP were associated with elevations in apo E mRNA. Dexamethasone-treated macrophages had 6-fold increases in apo E mRNA by 48 h when compared with control macrophages. Macrophages stimulated with 8-bromo-cAMP for 48 h demonstrated a more modest but statistically significant (P < 0.001) 2.2-fold increase. Similar effects of dexamethasone, cholera toxin, TGF beta, and 8-bromo-cAMP on apo E secretion were also apparent in macrophage-derived foam cells. In addition to increasing apo E secretion in macrophages and foam cells, dexamethasone and 8-bromo-cAMP inhibited the down-regulation of apo E secretion mediated by LPS and GM-CSF. Finally, the increased apo E secretion by exogenous glucocorticoids or TGF beta was not species specific as similar effects were observed in rabbit peritoneal macrophages. Therefore, while macrophage activation results in decreased apo E synthesis, macrophages exposed to anti-inflammatory agents including dexamethasone, TGF beta, or following cAMP elevation demonstrate increased apo E secretion by a cholesterol-independent mechanism.
Atherosclerosis 1993 Oct
PMID:Exogenous glucocorticoids increase macrophage secretion of apo E by cholesterol-independent pathways. 828 Jan 84

Tumour necrosis factor alpha (TNF alpha) has been reported to play a key role in the pathogenesis of sepsis and chronic inflammatory diseases, including rheumatoid arthritis and atherosclerosis, suggesting that agents which inhibit TNF alpha production may have therapeutic utility for the treatment of such conditions. Production of TNF alpha by LPS (lipopolysaccharide)-stimulated murine, rat and human heparinized blood was investigated. LPS (1-100 micrograms/ml) caused a similar concentration- and time-dependent stimulation of TNF alpha production by rat and human blood, achieving levels of 750-5000 U/ml (L929 bioassay) at 6 h. In contrast, TNF alpha production by LPS-stimulated murine blood was poor and variable (0-150 U/ml). Dexamethasone and pentoxifylline caused a concentration-dependent inhibition of TNF alpha production by LPS-stimulated human and rat blood with IC50s of 0.26 +/- 0.05 and 73.0 +/- 26.4 microM for human and 5.7 +/- 1.8 nM and 20.6 +/- 8.0 microM for rat blood, respectively. Therefore, LPS-stimulated rat and human, but not murine, blood are suitable systems for the detection and evaluation of inhibitors of TNF alpha production.
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PMID:Production of TNF alpha by LPS-stimulated murine, rat and human blood and its pharmacological modulation. 831 28

Intimal thickening predisposes to atherosclerosis and is often associated with alterations of the vascular reactivity of the artery. We investigated whether dexamethasone inhibited the intimal thickening and reactivity changes induced by a silicone collar placed around the left rabbit carotid artery for 2 weeks. The sham-operated, right artery served as control. Dexamethasone (1 mg/kg/day), given in the drinking water (n = 10) or by a subcutaneous minipump (n = 10), abolished intimal thickening compared to that of both placebo groups (n = 10). Both dexamethasone and the collar suppressed the isometric force development of isolated segments elicited by KCl in organ chamber experiments. The collar raised the sensitivity to serotonin (5-hydroxytryptamine, 5-HT) and the maximum force development (Emax) after normalization for the KCl responses. Dexamethasone exerted complex effects on 5-HT contractions in sham arteries: the curves often became biphasic, and sensitivity and Emax of the first phase were depressed by dexamethasone. In contrast, dexamethasone raised the hypersensitivity of collared arteries to 5-HT even further. Collar and dexamethasone did not influence endothelium-dependent relaxations elicited by acetylcholine or the calcium ionophore A-23187. It is concluded that dexamethasone interfered with neo-intima formation in the collar model, presumably by inhibition of smooth muscle cell migration and/or proliferation, without restoring contractile behaviour. Therefore, the collar-induced alterations in the reactivity of the smooth muscle cells in the media appear to be unrelated to the process of intimal thickening.
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PMID:Dexamethasone influences intimal thickening and vascular reactivity in the rabbit collared carotid artery. 875 Jul 42


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