HDL and arteriosclerosis: Beyond reverse cholesterol transport

Atherosclerosis

Volumn 161, Issue 1, 2002, Pages 1-16

  Nofer, Jerzy Roch ^a   Kehrel, Beate ^a   Fobker, Manfred ^a   Levkau, Bodo ^a   Assmann, Gerd ^a   Eckardstein, Arnold Von ^a  

^a UNIVERSITY OF MÜNSTER   (Germany)

Author keywords

Anti atherogenicity; Cholesterol; High density lipoprotein (HDL); Metabolism

Indexed keywords

APOLIPOPROTEIN A1; APOLIPOPROTEIN A4; APOLIPOPROTEIN E; ARYLDIALKYLPHOSPHATASE; BLOOD CLOTTING FACTOR 10; CD59 ANTIGEN; CHOLESTEROL ESTER TRANSFER PROTEIN; CYCLIN A; CYCLIN D1; CYCLIN E; CYCLOOXYGENASE 2; ENDOTHELIN 1; EPIDERMAL GROWTH FACTOR; FIBROBLAST GROWTH FACTOR; HIGH DENSITY LIPOPROTEIN; HIGH DENSITY LIPOPROTEIN CHOLESTEROL; INSULIN; LOW DENSITY LIPOPROTEIN; MITOGEN ACTIVATED PROTEIN KINASE; NATRIURETIC PEPTIDE TYPE C; NITRIC OXIDE; PHOSPHATIDYLCHOLINE STEROL ACYLTRANSFERASE; PHOSPHOLIPID TRANSFER PROTEIN; PLATELET DERIVED GROWTH FACTOR; PROSTACYCLIN; PROTEIN C; PROTEIN KINASE C; PROTEIN S; TRANSFERRIN; UNINDEXED DRUG;

APOPTOSIS; ARTERIOSCLEROSIS; BLOOD CLOTTING; CELL CYCLE; CELL GROWTH; CELL PROLIFERATION; CELL PROTECTION; CHEMOTAXIS; CHOLESTEROL BLOOD LEVEL; CHOLESTEROL TRANSPORT; COMPLEMENT ACTIVATION; DISEASE PREDISPOSITION; ENDOTHELIUM CELL; ENZYME ACTIVITY; FIBRINOLYSIS; HUMAN; ISCHEMIC HEART DISEASE; LEUKOCYTE ADHERENCE; LIPOPROTEIN METABOLISM; MITOGENESIS; MONOCYTE; NONHUMAN; OXIDATION; PRIORITY JOURNAL; PROTECTION; PROTEIN EXPRESSION; PROTEIN SYNTHESIS; REVIEW; RISK FACTOR; SMOOTH MUSCLE FIBER; THROMBOCYTE ACTIVATION;

ANIMALS; ARTERIOSCLEROSIS; BIOLOGICAL TRANSPORT, ACTIVE; CELL DIVISION; CHEMOTAXIS, LEUKOCYTE; ENDOTHELIUM, VASCULAR; HUMANS; LIPOPROTEINS, HDL; MODELS, BIOLOGICAL; PLATELET ACTIVATION;

EID: 0036189524     PISSN: 00219150     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0021-9150(01)00651-7     Document Type: Review

References (207)

1. Physiological role and clinical relevance of high-density lipoprotein subclasses
2. A solely apolipoprotein E containing plasma lipoprotein with electrophoretic gamma-mobility takes up cellular cholesterol
3. Lipoproteins containing apolipoprotein A-IV but not apolipoprotein A-I take up and esterify cell-derived cholesterol in plasma
4. High density lipoproteins - The clinical implication of recent studies
5. Relation of high-density lipoprotein cholesterol and triglycerides to incidence of atherosclerotic coronary artery disease (the PROCAM experience). Prospective Cardiovascular Munster Study
6. High density lipoprotein cholesterol as a predictor of coronary heart disease. The PROCAM experience and pathophysiological implication for reverse cholesterol transport
7. Familial lipoprotein disorders in patients with coronary disease
8. Associations of obesity markers, insulin, and sex hormones with HDL-cholesterol levels in Turkish and German individuals
9. Prevention of coronary heart disease by raising of high density lipoprotein cholesterol
10. Systemic inflammatory parameters in patients with atherosclerosis of the coronary and peripheral arteries
11. High-sensitivity C-reactive protein: Potential adjunct for global risk assessment in the primary prevention of cardiovascular disease
12. Short-term prognostic value of lipid measurements for coronary events in patients with angina pectoris
13. An overview of reverse cholesterol transport
14. Role of liver in the maintenance of cholesterol and low density lipoprotein homeostasis in different animal species
15. Acceleration of reverse cholesterol transport
16. HDL and atherosclerosis: Role of cholesterol efflux and reverse cholesterol transport
17. Atherosclerosis and the arterial smooth muscle cell
18. Lipoprotein increase growth of mitogen-stimulated arterial smooth muscle cells
19. Role of lipoproteins in growth of human adult arterial endothelial and smooth muscle cells in lipoprotein-deficient serum
20. Lipoproteins may provide fatty acids necessary for human lymphocyte proliferation by both low-density receptor-dependent and -independent mechanisms
21. Stimulation of proliferation in stationary primary cultures of monkey aortic smooth muscle cells: I. Effects of lipoprotein fractions of hyperlipemic serum and lymph
22. Stimulation of proliferation in stationary primary cultures of monkey aortic smooth muscle cells: II. Effect of varying concentrations of hyperlipemic serum and low density lipoproteins of varying dietary fat origins
23. Growth-stimulating effect of lipoproteins on human arterial smooth-muscle cells and lung fibroblasts is due to apo B-containing lipoproteins, type LDL and VLDL, and requires LDL receptors
24. Factors controlling the proliferative rate, final cell density, and life span of bovine vascular smooth muscle cells in culture
25. Low- and high density lipoproteins as mitogenic factors for vascular smooth muscle cell: Individual, additive and synergistic effects
26. Lipoproteins are primary mitogens and growth promoters for human arterial smooth muscle cells and lung fibroblasts in vitro
27. High density lipoproteins induce cell cycle entry in vascular smooth muscle cells via mitogen activated protein kinase-dependent pathway
28. Modulation of gene expression by high and low density lipoproteins in human vascular smooth muscle cells
29. Lipoproteins induce expression of the early growth response gene-1 in vascular smooth muscle cells from rat
30. 3 stimulates multiple signaling pathways in human skin fibroblasts
31. 3 and LDL is markedly reduced in cultured fibroblasts from Tangier patients
32. Defective regulation of phosphatidylcholine-specific phospholipases C and D in a kindred with Tangier disease. Evidence for the involvement of the phosphatidylcholine breakdown in HDL-mediated cholesterol efflux mechanisms
33. Protein kinase C as a mediator of high-density lipoprotein receptor-dependent efflux of intracellular cholesterol
34. 2+ in cultured fibroblasts
35. High density lipoprotein increases intracellular calcium levels by releasing calcium from internal stores in human endothelial cells
36. Phosphoproteins regulated by the interaction of high-density lipoproteins with human skin fibroblasts
37. High density lipoproteins stimulate mitogen-activated protein kinases in human skin fibroblasts
38. Rapid purification and activity of apolipoprotein C1 on the proliferation of bovine vascular endothelial cells in vitro
39. Proliferative effect of high density lipoprotein (HDL) and HDL fractions (HDL1,2, HDL3) on virus transformed lymphoblastoid cells
40. High density lipoprotein 3 binding sites are related to DNA biosynthesis in the adenocarcinoma cell line A549
41. High density lipoprotein reduces epidermal growth factor-induced DNA synthesis in vascular smooth muscle cells
42. Apolipoprotein E inhibits platelet-derived growth factor-induced vascular smooth muscle cell migration and proliferation by suppressing signal transduction and preventing cell entry to G1 phase
43. Apolipoprotein inhibition of vascular smooth muscle cell proliferation but not the inhibition of migration is mediated through activation of inducible nitric oxide synthase
44. Activation of phosphatidylinositol-specific phospholipase C (PI-PLC) by HDL-associated lysosphingolipids: Involvement in mitogenesis but not in cholesterol efflux
45. Endothelial cell functions. Relationship to atherogenesis
46. Endothelial function and atherosclerosis
47. Endothelial dysfunction and atherosclerosis
48. Endothelium and vascular injury in hypertension and atherosclerosis
49. Primary endothelial dysfunction: Atherosclerosis
50. Paradoxical vasoconstriction induced by acetylcholine in atherosclerotic coronary arteries
51. Direct vasoconstriction and endothelium-dependent vasodilation: Mechanisms of acetylcholine effects on coronary flow and arterial diameter in patients with nonstenotic coronary arteries
52. Evidence of endothelial dysfunction in angiographically normal coronary arteries of patients with coronary artery disease
53. Divergent effects of serotonin on coronary-artery dimensions and blood flow in patients with coronary atherosclerosis and control patients
54. Effect of intracoronary serotonin on coronary vessels in patients with stable angina and patients with variant angina
55. The atherogenic lipoprotein phenotype and vascular endothelial dysfunction
56. Constantly low HDL-cholesterol concentration relates to endothelial dysfunction and increased in vivo LDL-oxidation in healthy young men
57. Endothelium-dependent and -independent functions are impaired in patients with coronary heart disease
58. Protective effect of high density lipoprotein on endothelium-dependent vasodilation
59. Low density lipoprotein cholesterol and coronary microvascular dysfunction in hypercholesterolemia
60. High density lipoprotein reverses inhibitory effect of oxidized low density lipoprotein on endothelium-dependent arterial relaxation
61. Oxidized lipoproteins inhibit endothelium-dependent vasodilation. Effects of pressure and high-density lipoprotein
62. Complexes of apoA-1 with phosphatidylcholine suppress dysregulation of arterial tone by oxidized LDL
63. Effects of high-density lipoprotein on acetylcholine-induced coronary vasoreactivity
64. Coronary atherosclerotic wall thickening and vascular reactivity in humans. Elevated high-density lipoprotein levels ameliorate abnormal vasoconstriction in early atherosclerosis
65. High density lipoprotein prevents oxidized low density lipoprotein-induced inhibition of endothelial nitric-oxide synthase localization and activation in caveolae
66. Effects of high-density lipoproteins on intracellular pH and proliferation of human vascular endothelial cells
67. HDL and Apo A prevent cell death of endothelial cells induced by oxidized LDL
68. High-density lipoproteins protect endothelial cells from tumor necrosis factor-alpha-induced apoptosis
69. Lipolyzed hypertriglyceridemic serum and triglyceride-rich lipoprotein cause lipid accumulation in and are cytotoxic to cultured human endothelial cells. High density lipoproteins inhibit this cytotoxicity
70. Complement activation in hypercholesterolemia
71. Inhibition of the lytic action of cell-bound terminal complement-components by human high density lipoproteins and apoproteins
72. High-density lipoprotein and its apolipoproteins inhibit cytolytic activity of complement. Studies on the nature of inhibitory moiety
73. The terminal complement protein C5b-9 augments binding of high density lipoprotein and its apolipoproteins A-I and A-II to human endothelial cells
74. Interaction between apolipoproteins A-I and A-II and the membrane attack complex of complement. Affinity of the apoproteins for polymeric C9
75. High-density lipoproteins can act as carriers of glycophosphoinositol lipid-anchored CD59 in human plasma
76. Complement C6 deficiency protects against diet-induced atherosclerosis in rabbits
77. Pharmacodynamic profile of prostacyclin
78. Is the anti-atherosclerotic potency of HDL modulated by the origin of HDL?
79. 2 synthetase activity
80. 2 synthase activity
81. Stimulation of arterial endothelial cell prostacyclin synthesis by high density lipoproteins
82. Lipoprotein-induced prostacyclin production in endothelial cells and effects of lipoprotein modification
83. High-density lipoproteins differentially modulate cytokine-induced expression of E-selectin and cyclooxygenase-2
84. HDL-induced prostacyclin release in smooth muscle cells is dependent on cyclooxygenase-2 (Cox-2)
85. Effect of human native low-density and high-density lipoproteins on prostaglandin production by mouse macrophage cell line P388D1: Possible implications in the pathogenesis of atherosclerosis
86. The effect of high density lipoprotein subfractions on endothelial eicosanoid secretion
87. 2 half-life regulated by high density lipoprotein is decreased in acute myocardial infarction and unstable angina pectoris
88. 2) stabilizing factor is identical to apolipoprotein A-I (Apo A-I): A novel function of apo A-I
89. 2 binding and stabilising protein in human blood
90. Human high density lipoproteins stimulate endothelin-1 release by cultured human renal proximal tubular cells
91. High density lipoproteins stimulate the production and secretion of endothelin-1 from cultured bovine aortic endothelial cells
92. Stimulation of endothelin-1 release by low density and very low density lipoproteins in cultured human endothelial cells
93. Lipoproteins regulate C-type natriuretic peptide secretion from cultured vascular endothelial cells
94. Expression of intercellular adhesion molecule-1 in atherosclerotic plaques
95. Adhesion molecules on the endothelium and mononuclear cells in human atherosclerotic lesions
96. Vascular cell adhesion molecule-1 is expressed in human coronary atherosclerotic plaques. Implications for the mode of progression of advanced coronary atherosclerosis
97. Various cell types in human atherosclerotic lesions express ICAM-1. Further immunocytochemical and immunochemical studies employing monoclonal antibody 10F3
98. Endothelial expression of a mononuclear leukocyte adhesion molecule during atherogenesis
99. An atherogenic diet rapidly induces VCAM-1, a cytokine-regulatable mononuclear leukocyte adhesion molecule, in rabbit aortic endothelium
100. Lysophosphatidylcholine, a component of atherogenic lipoproteins, induces mononuclear leukocyte adhesion molecules in cultured human and rabbit arterial endothelial cells
101. Lipoprotein lipase-mediated lipolysis of very low density lipoproteins increases monocyte adhesion to aortic endothelial cells
102. Function and activation of NF-kappaB in the immune system
103. Monocyte transmigration induced by modification of low density lipoprotein in co-cultures of human aortic wall cells is due to induction of monocyte chemotactic protein 1 synthesis and is abolished by high density lipoprotein
104. High-density lipoproteins inhibit cytokine-induced expression of endothelial cell adhesion molecules
105. Inhibition of VCAM-1 expression in endothelial cells by reconstituted high density lipoproteins
106. Factors influencing the ability of HDL to inhibit expression on vascular cell adhesion molecule-1 in endothelial cells
107. Phospholipid composition of reconstituted high density lipoproteins influences their ability to inhibit endothelial cell adhesion molecule expression
108. High density lipoproteins (HDL) interrupt the sphingosine kinase signaling pathway. A possible mechanism for protection against atherosclerosis by HDL
109. -/- mice
110. Apo A-I inhibits foam cell formation in Apo E-deficient mice after monocyte adherence to endothelium
111. Structural recognition of a novel fibrinogen gamma chain sequence [117-133] by intercellular adhesion molecule-1 mediates leukocyte-endothelium interaction
112. Reconstituted high density lipoprotein modulates adherence of polymorphonuclear leukocytes to human endothelial cells
113. High density lipoprotein inhibits fibrinogen binding on adenosine diphosphate-activated activated monocytes
114. Haemostatic function and cardiovascular death: Early results of a prospective study
115. Fibrinolytic activity, clotting factors, and long-term incidence of ischaemic heart disease in the Northwick Park Heart Study
116. Factor-VII activity and ischaemic heart disease: Fatal and non-fatal events
117. Plasminogen activator and plasminogen activator inhibitor activities in men with coronary artery disease
118. The status of PAI-1 as a risk factor for arterial and thrombotic disease: A review
119. Increased plasminogen activator inhibitor and tissue plasminogen activator levels in subjects with electrocardiographic abnormality indicative of ischaemic heart disease: A cross-sectional study in Norsjo, Sweden
120. Tissue plasminogen activator and risk of myocardial infarction. The Rotterdam study
121. Fibrin D-dimer, tissue plasminogen activator, plasminogen activator inhibitor, and the risk of major ischemic heart disease in the Caerphilly study
122. Enhanced tissue factor activity and plasminogen activator inhibitor-1 antigen in human umbilical vein endothelial cells incubated with lipoproteins
123. Effects of lipids and lipoproteins on thrombosis and rheology
124. Plasma high density lipoproteins inhibit the activation of coagulation factor X by factor VIIa and tissue factor
125. Anti-coagulant activity of tissue factor pathway inhibitor in human plasma is preferentially associated with dense subspecies of LDL and HDL and with Lp(a)
126. HDL and apolipoprotein A-I protect erythrocytes against the generation of procoagulant activity
127. Plasma lipoproteins support prothrombinase and other procoagulant enzymatic complexes
128. Atherogenic lipoproteins support assembly of the prothrombinase complex and thrombin generation: Modulation by oxidation and vitamin E
129. High-density lipoprotein enhancement of anti-coagulant activities of plasma protein S and activated protein C
130. Hypertriglyceridemia and regulation of fibrinolytic activity
131. Fibrinolytic factors and the risk of myocardial infarction or sudden death in patients with angina pectoris. ECAT Study Group. European concerted action on thrombosis and diabetes
132. Lipoproteins inhibit the secretion of tissue plasminogen activator from human endothelial cells
133. Impact of anti-oxidants and HDL on glycated LDL-induced generation of fibrinolytic regulators from vascular endothelial cells
134. Differential effects of reconstituted high-density lipoprotein on coagulation, fibrinolysis and platelet activation during human endotoxemia
135. Evidence that high-density lipoprotein cholesterol is an independent predictor of acute platelet-dependent thrombus formation
136. Platelet interaction with high and low density lipoproteins
137. Characterization of the effect of plasma lipoproteins on platelet function in vitro
138. The aggregation of isolated human platelets in the presence of lipoproteins and prostacyclin
139. 3-mediated inhibition of thrombin-induced platelet aggregation and fibrinogen binding occurs vie decreased production of phosphoinositide-derived second messengers 1,2-diacylglycerol and inositol 1,4,5-tris-phosphate
140. Binding of apoE-rich high density lipoprotein particles by saturable sites on human blood platelets inhibits agonist-induced platelet aggregation
141. Apolipoprotein E inhibits platelet aggregation through the L-Arginine: Nitric oxide pathway
142. Inhibitory effect of high-density lipoprotein on platelet function is mediated by increase in nitric oxide synthase activity in platelets
143. Identification and characterization of LRP8 (apoER2) in human blood platelets
144. The role of apoE in inhibitory effects of apoE-rich HDL on platelet function
145. 3 activated phospholipase C in human platelets
146. + antiport in human platelets
147. 3 stimulated platelets
148. Pertussis toxin sensitive G-protein coupling of HDL receptor to phospholipase C in human platelets
149. 3 activates phospholipase D in normal but not in glycoprotein IIb/IIIa-deficient platelets
150. Interaction of plasma lipoproteins with human platelets
151. Specific binding sites on human blood platelets for plasma lipoproteins
152. 111In-labeled HDL to platelets form normolipemic volunteers and patients with heterozygous familial hypercholesterolemia
153. Purification and identification of the lipoprotein-binding proteins from human blood platelet membrane
154. Platelet HDL(3) binding sites are not related to integrin alpha(IIb)beta(3) (GPIIb-IIIa)
155. Human CD36 is a high affinity receptor for the native lipoproteins HDL, LDL, and VLDL
156. Mechanisms for regulating platelet high density lipoprotein type 3 binding sites: Evidence that binding sites are downregulated by a protein kinase C-dependent mechanism
157. Increased platelet aggregation and decreased high-density lipoprotein cholesterol in woman on oral contraceptives
158. Recostituted high density lipoprotein (rHDL) modulates platelet activity in vitro and ex vivo
159. Anti-oxidants and atherosclerotic heart disease
160. Oxidation of low density lipoproteins in the pathogenesis of atherosclerosis
161. Oxidized LDL and atherogenesis
162. LDL-induced cytotoxicity and its inhibition by HDL in human vascular smooth muscle cells and endothelial cells in culture
163. High-density lipoprotein inhibits the oxidative modification of low-density lipoprotein
164. Normal high density lipoprotein inhibits three steps in the formation of mildly oxidized low density lipoprotein. Steps 2 and 3
165. High density lipoprotein is the major carrier of lipid hydroperoxides in human blood plasma from fasting donors
166. The scavenger receptor serves as a route for internalization of lysophoysphatidylcholine in oxidized low density lipoprotein-induced macrophage proliferation
167. Oxidized phospholipids and isoprostanes in atherosclerosis
168. HDL apolipoprotein A-I attenuates oxidative modification of low density lipoprotein: Studies in transgenic mice
169. Decreased protection by HDL from poorly controlled type 2 diabetic subjects against LDL oxidation may be due to the abnormal composition of HDL
170. Oxidation of high density lipoproteins II. Evidence for direct reduction of lipid hydroperoxides by methionine residues of apolipoproteins A-I and apo A-II
171. Site-specific methionine sulfoxide formation is the structural basis of chromatographic heterogeneity of apolipoprotein A-I, C-II and C-III
172. Structural and functional properties of natural and chemical variants of apolipoprotein A-I
173. Paroxonase prevents accumulation of lipoperoxides in low-density lipoproteins
174. The Yin and Yang of oxidation in the development of fatty streak
175. Protective effect of high density lipoprotein-associated paroxonase. Inhibition of the biological activity of minimally oxidized low density lipoproteins
176. Human serum paraoxonase (PON1) Q and R selectively decrease lipid peroxides in human coronary artery diesease and carotid atherosclerotic lesions: PON1 esterase and peroxidase-like activities
177. Genetic-dietary regulation of serum paroxonase expression and its role in atherogenesis in a mouse model
178. Mildly oxidized LDL induces an increased apolipoprotein J/paroxonase ratio
179. Paraoxonase activity is reduced by a pro-atherosclerotic diet in rabbits
180. Short-term feeding of atherogenic diet results in reduction of HDL and paraoxonase that may be mediated by an immune mechanism
181. Glycation impaires high density lipoprotein function
182. Effect of overexpression of human apo A-I in C57BL/6 and C57BL/6 apo E-deficient mice on 2 lipoprotein-associated enzymes, platelet-activating factor acetylhydrolase and paraoxonase: Comparison of adenovirus-mediated human apo A-I gene transfer and human apo A-I transgenesis
183. Mice lacking serum paraoxonase are susceptible to organophosphate toxicity and atherosclerosis
184. Combined serum paraoxonase knockout/apolipoprotein E knockout mice exhibit increased lipoprotein oxidation and atherosclerosis
185. Paraoxonase inhibits high density lipoprotein oxidation and preserves its functions. A possible peroxidative role for paraoxonase
186. High density lipoprotein loses its effect to stimulate efflux of cholesterol from foam cells after oxidative modification
187. Reduced cholesterol efflux to mildly oxidized high density lipoprotein
188. Oxidation of high density lipoproteins: Characterization and effects on cholesterol efflux from J774 macrophages
189. Native lipoproteins inhibit platelet activation induced by oxidized lipoproteins
190. The molecular basis of the human serum paraoxonase activity polymorphism
191. Molecular basis for the polymorphic forms of human paraoxonase arylesterase: Glutamine or arginine at position 191 for the respective A or B alloenzymes
192. Paraoxonase-gene polymorphism associated with coronary heart disease: Support for the oxidative damage hypothesis?
193. Gin-Arg 192 polymorphism of paraoxonase and coronary heart disease in type 2 diabetes
194. DNA polymorphism in two paraoxonase genes (PON1 and PON2) are associated with the risk of coronary heart disease
195. A variant of human paraoxonase arylesterase (HUMPONA) gene is a risk factor for coronary heart disease
196. Evidence for the association between paraoxonase gene polymorphism and atherosclerotic disease
197. Paraoxonase activity in two healthy populations with differing rates of coronary heart disease
198. Risk of myocardial infarction associated with Gln/Arg 192 polymorphism in the human paraoxonase gene and diabetes mellitus, The REGICOR Investigators
199. Paraoxonase gene polymorphism are associated with carotid arterial wall thickness in subjects with familial hypercholesterolemia
200. MRI cerebral white matter lesions and paraoxonase PON1 polymorphism: Three-year follow up of the Austrian stroke prevention study
201. Paraoxonase polymorphism (Gln192Arg) as a determinant of the response of human coronary arteries to serotonin
202. Genetic polymorphism of paraoxonase and the risk of coronary heart disease
203. High density lipoprotein plasma fractions inhibit aortic fatty streaks in cholesterol-fed rabbit
204. Regression of atherosclerotic lesions by high density lipoprotein plasma fraction in the cholesterol-fed rabbit
205. HDL causes mesangial cell mitogenesis through a tyrosine kinase-dependent receptor mechanism
206. High density lipoproteins stimulate molecular weight 80 K protein phosphorylation in human trophoblast cells: Evidence for a protein kinase C-dependent pathway in human placental lactogen release
207. High density lipoproteins stimulate placental lactogene release and adenosine 3′,5′-monophosphate (cAMP) production in human trophoblast cells: Evidence for cAMP as a second messenger in human placental lactogen release