92 results on '"Bar RS"'
Search Results
2. Fatal infectious mononucleosis in a family
- Author
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Bar Rs, Henle W, Hewetson Jf, DeLor Cj, Clausen Kp, and Hurtubise P
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Adult ,Male ,Herpesvirus 4, Human ,Mononucleosis ,Adolescent ,Biopsy ,T-Lymphocytes ,Fluorescent Antibody Technique ,Immunoglobulins ,Lymphocyte Activation ,Virus ,Neutralization Tests ,Fatal infectious mononucleosis ,medicine ,Leukocytes ,Humans ,X-Linked Lymphoproliferative Syndrome ,Infectious Mononucleosis ,Child ,B-Lymphocytes ,business.industry ,Cell Membrane ,General Medicine ,medicine.disease ,Virology ,Microscopy, Electron ,Liver ,DNA, Viral ,Lymphocyte activation ,Lymph Nodes ,Lymphoproliferative disease ,business ,Liver pathology - Abstract
A 16-year-old boy with a fulminating lymphoproliferative disease, initially believed to be infectious mononucleosis, died within eight days. A herpes-group virus was found on electron micr...
- Published
- 1974
3. Adiponectin and C-reactive protein in obesity, type 2 diabetes, and monodrug therapy.
- Author
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Putz DM, Goldner WS, Bar RS, Haynes WG, and Sivitz WI
- Subjects
- Adiponectin, Blood Glucose drug effects, Blood Glucose metabolism, Body Composition, Cross-Over Studies, Female, Glyburide therapeutic use, Glycated Hemoglobin metabolism, Humans, Insulin blood, Insulin Resistance, Leptin blood, Linear Models, Lipids blood, Male, Metformin therapeutic use, Middle Aged, Sex Factors, C-Reactive Protein metabolism, Diabetes Mellitus, Type 2 blood, Diabetes Mellitus, Type 2 drug therapy, Hypoglycemic Agents therapeutic use, Intercellular Signaling Peptides and Proteins blood, Obesity blood
- Abstract
To learn more about the factors that regulate adipokines in diabetes, we examined fasting plasma concentrations of adiponectin and C-reactive protein (CRP) in well-characterized groups of age-matched individuals classified as: (1) type 2 diabetes; (2) impaired fasting glucose or mild diabetes (IFG/mild DM); (3) obese, matched for body mass index (BMI); and (4) non-obese. Diabetic subjects were also studied on no phamacologic treatment, after 3 months randomization to metformin or glyburide, and after 3 months crossover to the opposite drug. CRP decreased and adiponectin increased progressively between subjects in groups 1 through 4. CRP was significantly associated with percent (r = 0.45) and total (r = 0.50) fat, insulin sensitivity as S(I) (r = -0.39) or homeostasis model assessment of insulin resistance [HOMA (IR)] (r = -0.36), and hemoglobin A(1c) (HbA(1c)) (r = 0.41). The relationship of CRP to percent fat appeared to be logarithmic and log CRP varied with percent fat independent of gender. Adiponectin concentration was significantly associated with insulin sensitivity as S(I) (r = 0.55) or HOMA (IR) (r = -0.46). Adiponectin concentrations were higher among women overall (all groups included) but not in women classified as type 2 diabetes. Although mean adiponectin was higher in subjects classified as non-obese compared to obese, adiponectin, in sharp contrast to leptin (previously reported data) and to CRP, varied markedly when expressed as a function of adiposity. Multiple regression models confirmed the strong relationship of adiponectin to insulin sensitivity, as well as the relationships of CRP to adiposity and insulin sensitivity. Glyburide treatment of diabetes decreased CRP and did so even though body weight increased. We conclude that both CRP and adiponectin correlate strongly to S(I). CRP, in contrast to adiponectin, is far more dependent on adiposity. The relationship between CRP (like leptin) and gender depends on how CRP is expressed relative to adiposity. Our data raise the possibility that gender differences in adiponectin may be lost in diabetes. Finally, pharmacologic treatment of diabetes may modulate CRP independent of adiposity.
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- 2004
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4. Effect of an insulin-like growth factor binding protein fusion protein on thymidine incorporation in neuroblastoma and rhabdomyosarcoma cell lines.
- Author
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Dake BL, Boes M, Bach LA, and Bar RS
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- Animals, Cattle, Cell Division drug effects, Cell Line, Tumor cytology, Cell Line, Tumor drug effects, Cell Line, Tumor metabolism, Endothelium, Vascular cytology, Endothelium, Vascular metabolism, Insulin-Like Growth Factor Binding Protein 3 metabolism, Insulin-Like Growth Factor Binding Protein 6 metabolism, Recombinant Fusion Proteins metabolism, Recombinant Fusion Proteins pharmacology, Thymidine pharmacokinetics, Insulin-Like Growth Factor Binding Protein 3 pharmacology, Insulin-Like Growth Factor Binding Protein 6 pharmacology, Neuroblastoma, Rhabdomyosarcoma
- Abstract
A fusion protein, FP 6/3, composed of IGF binding protein (IGFBP)-6 and IGFBP-3 was synthesized where the complete sequences of each binding protein were fused together into a single chimeric protein. The orientation of this fusion protein's structure has the N terminus of IGFBP-3 fused to the C terminus of IGFBP-6, leaving the key binding areas of each open. FP 6/3 bound to cells via its IGFBP-3 component and retained the increased affinity for IGF-II via its IGFBP-6 component. The effect of FP 6/3 on growth was determined in cell lines from both neuroblastoma and rhabdomyosarcoma, where IGF-II is an autocrine growth factor. In studies using FP 6/3, IGFBP-3, or IGFBP-6, a growth inhibition effect was shown for all when present under coincubation conditions with IGF-II. However, with transient exposure, FP 6/3 was the only IGFBP that retained this growth-inhibition property. Under transient exposure conditions, FP 6/3 was found to be effective when exposure was limited to as few as 10 min and concentrations were as low as 1 nm. These findings with FP 6/3 suggest that it potentially could lead be used as therapy against cancers in which IGF-II is an autocrine growth factor because it brings an inhibition action directly to tumor cells.
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- 2004
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5. Leptin and body fat in type 2 diabetes and monodrug therapy.
- Author
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Sivitz WI, Wayson SM, Bayless ML, Larson LF, Sinkey C, Bar RS, and Haynes WG
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- Body Mass Index, Cholesterol, HDL blood, Cross-Over Studies, Diabetes Mellitus, Type 2 physiopathology, Fatty Acids, Nonesterified blood, Female, Glyburide therapeutic use, Glycated Hemoglobin analysis, Humans, Insulin metabolism, Insulin Secretion, Male, Metformin therapeutic use, Middle Aged, Adipose Tissue, Body Composition, Diabetes Mellitus, Type 2 drug therapy, Hypoglycemic Agents therapeutic use, Leptin blood
- Abstract
To better understand the relations among leptin, insulin, and body fat during the metabolic progression to diabetes and during drug monotherapy, metabolic parameters were examined in subjects classified as 1) type 2 diabetes; 2) impaired fasting glucose or mild diabetes mellitus; 3) nondiabetic, matched for body mass index (BMI); and 4) nonobese, nondiabetic. Diabetic subjects were also studied during no pharmacological treatment, after 3 months of randomization to metformin or glyburide, and after 3 months of cross-over to the opposite drug. Log leptin correlated more with percent body fat (slope, 0.042; confidence interval, 0.036-0.047; r(2) = 0.826; P < 0.0001) than with total fat mass, percent truncal or nontruncal fat, or BMI. When normalized to percent fat, leptin did not differ by gender. Leptin normalized to percent fat was 35% less in untreated diabetes than that in BMI-matched controls (P < 0.001). Leptin normalized to percent fat was increased by 25% (P < 0.01) as a result of glyburide therapy compared with pretreatment values, but was unchanged by therapy with metformin. Across a spectrum of subjects with diabetes, impaired fasting glucose/mild diabetes, or BMI-matched nondiabetic controls, normalized leptin significantly correlated with glucose-induced insulin release, but not with insulin sensitivity. Our data suggest that plasma leptin is reduced in untreated type 2 diabetes probably as a consequence of reduced insulin secretion and that circulating leptin concentrations are differentially affected by monodrug therapy.
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- 2003
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6. IGF-I and IGFBP-3 transport in the rat heart.
- Author
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Boes M, Dake BL, Booth BA, Sandra A, Bateman M, Knudtson KL, and Bar RS
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- Animals, Autoradiography, Binding Sites, Biological Transport, Cells, Cultured, Endothelium, Vascular metabolism, Insulin-Like Growth Factor Binding Protein 3 administration & dosage, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 4 genetics, Insulin-Like Growth Factor Binding Protein 4 metabolism, Insulin-Like Growth Factor I administration & dosage, Iodine Radioisotopes, Male, Microcirculation metabolism, Rats, Rats, Sprague-Dawley, Recombinant Fusion Proteins metabolism, Insulin-Like Growth Factor Binding Protein 3 metabolism, Insulin-Like Growth Factor I metabolism, Myocardium metabolism
- Abstract
Specific binding of IGF-binding protein (IGFBP)-3 was shown to be present in the isolated, beating rat heart. The uptake of perfused (125)I-labeled IGF-I in the beating heart was decreased to 9% by blocking IGF-I binding sites with the IGF-I analog Long R(3) (LR(3)) IGF-I. When LR(3) was perfused with complexes of (125)I-IGF-I. IGFBP-3, uptake of (125)I-IGF-I was decreased to 41%, which was significantly greater than LR(3) and (125)I-IGF-I (41 vs. 9%). These data suggest that both microvessel IGF-I and IGFBP-3 binding sites contribute to the transport of IGF-I in the perfused rat heart. This also suggests a novel and plausible mechanism whereby circulating IGFs reach sites of IGF bioactivity.
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- 2003
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7. Structure-function relationships of insulin-like growth factor binding protein 6 (IGFBP-6) and its chimeras.
- Author
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Boes M, Dake BL, Booth BA, Sandra A, Bateman M, Knudtson K, and Bar RS
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- Amino Acid Sequence, Animals, Cattle, Cells, Cultured, Dose-Response Relationship, Drug, Endothelium cytology, Endothelium, Vascular cytology, Heart physiology, Insulin-Like Growth Factor Binding Protein 4 metabolism, Insulin-Like Growth Factor II metabolism, Ligands, Molecular Sequence Data, Mutation, Perfusion, Protein Binding, Protein Structure, Tertiary, Rats, Sequence Homology, Amino Acid, Structure-Activity Relationship, Insulin-Like Growth Factor Binding Protein 4 chemistry, Insulin-Like Growth Factor Binding Protein 6 chemistry, Insulin-Like Growth Factor Binding Protein 6 physiology
- Abstract
Insulin-like growth factor binding protein 6 (IGFBP-6) is a high-affinity IGFBP with substantially greater affinity for insulin-like growth factor-II (IGF-II) than IGF-I. IGFBP-6(3) is a chimera which has a 20 amino acidC -terminal portion of IGFBP-6 switched with the homologous area of IGFBP-3, P3. Unlike IGFBP-4(3), in which the P3 region was exchanged for the homologous region of IGFBP-4 (P4), IGFBP-6(3) does not bind to endothelial cells. Double mutations were made with the P3 region exchanged as well as a second area differing from IGFBP-3 to form IGFBP-6(3)A and IGFBP-6(3)B, by replacing this area with the homologous region of IGFBP-3. Neither [(125)I]IGFBP-6(3)A nor IGFBP-6(3)B specifically bound to endothelial cells. However, each double mutant competed for [(125)I]IGFBP-3 binding to cultured cells. In the perfused heart, transendothelial transport of IGFBP-6 and IGFBP-6(3) was only 25% of similar transendothelial transport of perfused IGFBP-3. We conclude that chimeras of IGFBP-6 and IGFBP-3(6) clearly differ from IGFBP-4(3) in their ability to bind specifically to endothelial cells and in their capacity to undergo transendothelial transportation in the perfused heart.
- Published
- 2002
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8. IGFBP-3 binding to endothelial cells inhibits plasmin and thrombin proteolysis.
- Author
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Booth BA, Boes M, Dake BL, Knudtson KL, and Bar RS
- Subjects
- Animals, Cattle, Endothelium, Vascular cytology, Insulin-Like Growth Factor Binding Protein 3 chemistry, Protein Structure, Tertiary physiology, Endothelium, Vascular metabolism, Fibrinolysin metabolism, Insulin-Like Growth Factor Binding Protein 3 metabolism, Peptide Hydrolases metabolism, Thrombin metabolism
- Abstract
Insulin-like growth factor-binding protein (IGFBP)-3 contains a highly basic COOH-terminal heparin-binding region, the P3 region, which is thought to be important in the binding of IGFBP-3 to endothelial cells. IGFBP-3 and IGFBP-4, and their chimeras IGFBP-3(4) and IGFBP-4(3), were treated with plasmin and with thrombin, proteases known to cleave IGFBP-3. IGFBP-3 was highly susceptible to plasmin, whereas IGFBP-4 was less so. Substitution of the P3 region for the P4 region in IGFBP-4 (IGFBP-4(3)) increased the ability of the protease to digest IGFBP-4(3); substitution of the P4 region for the P3 region in IGFBP-3 (IGFBP-3(4)) decreased the digestion of IGFBP-3(4). When 125I-labeled IGFBP-3 or 125I-IGFBP-4(3) was first bound to vascular endothelial cells, subsequent proteolysis by either plasmin or thrombin was substantially inhibited. Proteolysis of 125I-IGFBP-3(4) was not inhibited in the presence of endothelial cells. The P3 peptide was cleaved by plasmin but not by thrombin. We conclude that the P3 region is central to proteolysis of IGFBP-3 by plasmin and thrombin, processes which were inhibited by association of IGFBP-3 with endothelial cells.
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- 2002
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9. Distribution of chimeric IGF binding protein (IGFBP)-3 and IGFBP-4 in the rat heart: importance of C-terminal basic region.
- Author
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Knudtson KL, Boes M, Sandra A, Dake BL, Booth BA, and Bar RS
- Subjects
- Amino Acid Sequence genetics, Animals, Base Sequence genetics, Cells, Cultured, Endothelium, Vascular cytology, Endothelium, Vascular metabolism, Extracellular Matrix metabolism, In Vitro Techniques, Male, Molecular Sequence Data, Myocardium cytology, Perfusion, Rats, Rats, Sprague-Dawley, Tissue Distribution, Chimera, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 3 metabolism, Insulin-Like Growth Factor Binding Protein 4 genetics, Insulin-Like Growth Factor Binding Protein 4 metabolism, Myocardium metabolism
- Abstract
IGF binding proteins-3 and -4, whether given in the perfused rat heart or given iv in the intact animal, cross the microvascular endothelium of the heart and distribute in subendothelial tissues. IGF binding protein-3, like IGF-I/II, localizes in cardiac muscle, with lesser concentrations in CT elements. In contrast, IGFBP-4 preferentially localizes in CT. In this study, chimeric IGF binding proteins were prepared in which a basic 20-amino-acid C-terminal region of IGF binding protein-3 was switched with the homologous region of IGF binding protein-4, and vice-versa, to create IGF binding protein-3(4) and IGF binding protein-4(3). Perfused IGF binding protein-3(4) behaved like IGF binding protein-4, localizing in connective tissue elements, whereas IGF binding protein-4(3) now localized in cardiac muscle at concentrations identical to perfused IGF binding protein-3. To determine whether these small mutations altered the affinity of the chimera for cells, the ability of (125)I-IGF binding protein-3(4) and (125)I-IGF binding protein-4(3) to bind to microvascular endothelial cells was determined and compared with IGF binding protein-3. IGF binding protein-3(4) retained 15% of the binding capacity of IGF binding protein-3, whereas IGF binding protein-4(3) bound to microvessel endothelial cells with higher affinity and greater total binding than that of IGF binding protein-3. We conclude that small changes in the C-terminal basic domain of IGF binding protein-3 and the corresponding region of IGF binding protein-4 can alter their affinity for cultured cells and influence their tissue distribution in the rat heart.
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- 2001
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10. Insulin-like growth factor (IGF)-binding protein-4 proteolytic degradation in bovine, equine, and porcine preovulatory follicles: regulation by IGFs and heparin-binding domain-containing peptides.
- Author
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Mazerbourg S, Zapf J, Bar RS, Brigstock DR, and Monget P
- Subjects
- Animals, Antibodies, Monoclonal pharmacology, Binding Sites, Carrier Proteins pharmacology, Cattle, Connective Tissue Growth Factor, Female, Follicular Fluid enzymology, Growth Substances pharmacology, Horses, Immediate-Early Proteins pharmacology, Insulin-Like Growth Factor Binding Protein 2 pharmacology, Insulin-Like Growth Factor Binding Protein 3 pharmacology, Insulin-Like Growth Factor Binding Protein 5 pharmacology, Insulin-Like Growth Factor I pharmacology, Insulin-Like Growth Factor II pharmacology, Peptide Fragments pharmacology, RNA-Binding Proteins, Ribosomal Proteins, Swine, Vitronectin pharmacology, Blood Coagulation Factors, Endopeptidases metabolism, Heparin metabolism, Insulin-Like Growth Factor Binding Protein 4 metabolism, Intercellular Signaling Peptides and Proteins, Ovarian Follicle enzymology, Ovulation, Somatomedins pharmacology
- Abstract
We recently showed that insulin-like growth factor-binding protein-4 (IGFBP-4) proteolytic degradation in ovine preovulatory ovarian follicles is IGF-dependent and regulated by the heparin-binding domain (HBD) from IGFBP-3 and from connective tissue growth factor (CTGF), heparan/heparin-interacting protein (HIP), and vitronectin. The present study investigated regulation of IGFBP-4 proteolytic degradation in porcine, bovine, and equine ovarian preovulatory follicles. Follicular fluid from such preovulatory follicles contains proteolytic activity, degrading exogenous IGFBP-4. An excess of IGF-I enhanced IGFBP-4 degradation. In contrast, IGFBP-2 or -3 or monoclonal antibodies against IGF-I or -II dose-dependently inhibited IGFBP-4 degradation, and IGF-I or -II reversed this inhibition in a dose-dependent manner. Heparin-binding peptides derived from the C-terminal domain of IGFBP-3 or -5 inhibited IGFBP-4 degradation. Other heparin-binding peptides derived from CTGF, HIP, and vitronectin also inhibited IGFBP-4 degradation, except in porcine follicles. Finally, IGFBP-3 that was mutated in its HBD was less effective at inhibiting IGFBP-4 degradation. Thus, in bovine, porcine, and equine preovulatory follicles, IGFBP-4 proteolytic degradation both depends on IGFs and is inhibited by peptides containing HBD. Overall, these results suggest that during terminal development of follicles to the preovulatory stage in domestic animal species, the increase in IGF bioavailability might enhance IGFBP-4 degradation. In contrast, in atretic follicles, the decrease in IGF bioavailability, resulting partly from the increase in IGFBP-2 (sow, heifer, mare) and IGFBP-5 (heifer) expression would participate in the decrease of IGFBP-4 degradation. In bovine atretic follicles, IGFBP-5 would also strengthen the inhibition of IGFBP-4 degradation by direct interaction of its HBD with the protease. The involvement of other HBD-containing proteins in the modulation of intrafollicular proteases degrading IGFBP-4 remains to be investigated.
- Published
- 2000
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11. Effect of IGFBP-derived peptides on incorporation of(35)SO(4)into proteoglycans.
- Author
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Booth BA, Boes M, Dake BL, Caldwell EE, Weiler JM, and Bar RS
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- Amino Acid Sequence, Animals, Cattle, Cells, Cultured, Endothelium, Vascular cytology, Endothelium, Vascular drug effects, Endothelium, Vascular metabolism, Insulin-Like Growth Factor Binding Protein 3 chemistry, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 3 pharmacology, Insulin-Like Growth Factor Binding Protein 5 chemistry, Insulin-Like Growth Factor Binding Protein 5 genetics, Insulin-Like Growth Factor Binding Protein 5 pharmacology, Insulin-Like Growth Factor Binding Protein 6 chemistry, Insulin-Like Growth Factor Binding Protein 6 genetics, Insulin-Like Growth Factor Binding Protein 6 pharmacology, Insulin-Like Growth Factor Binding Proteins chemistry, Insulin-Like Growth Factor Binding Proteins genetics, Molecular Sequence Data, Peptide Fragments chemistry, Peptide Fragments genetics, Peptide Fragments pharmacology, Insulin-Like Growth Factor Binding Proteins pharmacology, Proteoglycans metabolism, Sulfates metabolism
- Abstract
18 amino acid peptides from the C-terminal region of IGFBP-3, -5 (P3, P5), increased the incorporation of(35)SO(4)into proteoglycans in endothelial cells with greater stimulation in large vessel than microvessel cells. The homologous region of IGFBP-6 (P6) also stimulated sulfate uptake, but less potently than P3 and P5. P6 variants were synthesized with one or two amino acids changed to the basic amino acid in the equivalent position of P3. The P6 variants with one additional basic amino acid behaved similarly to P6. The P6 mutant with two altered amino acids was equipotent to P3. P3F, a scrambled version of P3 was less effective than P3. P3, P5, P6, P3F and all P6 variants all stimulated glucose uptake, which occurred only in microvessel cells. P1, P2, P4, and equimolar intact IGFBP-3 stimulated neither glucose uptake nor sulfate incorporation. Thus, C-terminal basic portions of IGFBP-3, -5 and -6 alter two specific functions of endothelial cells with sufficient differences to suggest mediation by distinct mechanisms., (Copyright 2000 Harcourt Publishers Ltd.)
- Published
- 2000
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12. Mechanism of coronary vasodilation to insulin and insulin-like growth factor I is dependent on vessel size.
- Author
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Oltman CL, Kane NL, Gutterman DD, Bar RS, and Dellsperger KC
- Subjects
- Animals, Coronary Circulation physiology, Coronary Vessels drug effects, Dogs, Female, Male, Microcirculation drug effects, Nitric Oxide Synthase metabolism, Potassium Channel Blockers, Potassium Channels physiology, Potassium Chloride pharmacology, Prostaglandin-Endoperoxide Synthases metabolism, Quaternary Ammonium Compounds pharmacology, Vasoconstriction physiology, Vasodilation physiology, Coronary Circulation drug effects, Insulin pharmacology, Insulin-Like Growth Factor I pharmacology, Vasodilation drug effects
- Abstract
Insulin and insulin-like growth factor I (IGF-I) influence numerous metabolic and mitogenic processes; these hormones also have vasoactive properties. This study examined mechanisms involved in insulin- and IGF-I-induced dilation in canine conduit and microvascular coronary segments. Tension of coronary artery segments was measured after constriction with PGF(2alpha). Internal diameter of coronary microvessels (resting diameter = 112.6+/-10.1 microm) was measured after endothelin constriction. Vessels were incubated in control (Krebs) solution and were treated with N(omega)-nitro-L-arginine (L-NA), indomethacin, or K(+) channel inhibitors. After constriction, cumulative doses of insulin or IGF-I (0.1-100 ng/ml) were administered. In conduit arteries, insulin produced modest maximal relaxation (32 +/- 5%) compared with IGF-I (66+/-12%). Vasodilation was attenuated by nitric oxide synthase (NOS) and cyclooxygenase inhibition and was blocked with KCl constriction. Coronary microvascular relaxation to insulin and IGF-I was not altered by L-NA, indomethacin, tetraethylammonium chloride, glibenclamide, charybdotoxin, and apamin; however, tetrabutylammonium chloride attenuated the response. In conclusion, insulin and IGF-I cause vasodilation in canine coronary conduit arteries and microvessels. In conduit vessels, NOS/cyclooxygenase pathways are involved in the vasodilation. In microvessels, relaxation to insulin and IGF-I is not mediated by NOS/cyclooxygenase pathways but rather through K(+)-dependent mechanisms.
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- 2000
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13. Insulin-like growth factor binding protein-4 proteolytic degradation in ovine preovulatory follicles: studies of underlying mechanisms.
- Author
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Mazerbourg S, Zapf J, Bar RS, Brigstock DR, Lalou C, Binoux M, and Monget P
- Subjects
- Animals, Female, Heparin metabolism, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 3 metabolism, Insulin-Like Growth Factor Binding Protein 3 pharmacology, Insulin-Like Growth Factor I pharmacology, Mutation physiology, Peptide Fragments pharmacology, Peptides chemical synthesis, Peptides pharmacology, Sheep, Somatomedins physiology, Follicular Phase physiology, Insulin-Like Growth Factor Binding Protein 4 metabolism, Ovarian Follicle metabolism, Peptide Hydrolases metabolism
- Abstract
The regulation of insulin-like growth factor binding protein (IGFBP)-4 proteolytic degradation by insulin-like growth factors (IGFs) has been largely studied in vitro, but not in vivo. The aim of this study was to investigate the involvement of IGFs, IGFBP-2, IGFBP-3, and IGFBP-3 proteolytic fragments in the regulation of IGFBP-4 proteolytic activity in ovine ovarian follicles. Follicular fluid from preovulatory follicles contains proteolytic activity degrading exogenous IGFBP-4. The addition of an excess of IGF-I enhanced IGFBP-4 proteolytic degradation, whereas addition of IGFBP-2 or -3 or monoclonal antibodies against IGF-I and -II dose dependently inhibited IGFBP-4 proteolytic degradation. IGF-I and IGF-II, but not LongR3-IGF-I, reversed this inhibition in a dose-dependent manner. C-terminal, but not N-terminal, proteolytic fragments derived from IGFBP-3 (aa 161-264), as well as heparin-binding domain-containing peptides derived from the C-terminal domain of IGFBP-3 and -5 also induced the inhibition of IGFBP-4 proteolytic degradation. Other heparin-binding domain-containing peptides derived from the connective tissue growth factor (CTGF) and from proteins not related to IGFBP, heparan/heparin interacting protein (HIP) and vitronectin, but not from p36 subunit of annexin II tetramer, inhibited IGFBP-4 degradation. Furthermore, IGFBP-3, mutated on its heparin-binding domain, was not able to inhibit IGFBP-4 proteolytic degradation. So, in ovine preovulatory follicles, IGFBP-4 proteolytic degradation both 1) depends on IGFs, and 2) is inhibited by IGFBP-3 via its C-terminal heparin-binding domain as well as by heparin-binding domain containing peptides. These data suggest that in early atretic follicles, the increase in IGFBP-2 participates in the decrease in IGFBP-4 degradation. In late atretic follicles, the increase in the levels of C-terminal IGFBP-3 proteolytic fragments, generated by IGFBP-3 degradation, as well as the increase in IGFBP-5 expression would strengthen the inhibition of IGFBP-4 degradation. This inhibition might be partly mediated by direct interaction of IGFBP-4 proteinase(s) and heparin-binding domain within the C-terminal region from IGFBP-3 and -5.
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- 1999
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14. Connective tissue growth factor (IGFBP-rP2) expression and regulation in cultured bovine endothelial cells.
- Author
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Boes M, Dake BL, Booth BA, Erondu NE, Oh Y, Hwa V, Rosenfeld R, and Bar RS
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- Animals, Aorta, Blotting, Northern, Cattle, Cells, Cultured, Colforsin pharmacology, Cyclic AMP pharmacology, Electrophoresis, Polyacrylamide Gel, Pulmonary Artery, RNA, Messenger analysis, Transforming Growth Factor beta pharmacology, Endothelium, Vascular metabolism, Gene Expression Regulation drug effects, Insulin-Like Growth Factor Binding Protein 2 genetics
- Abstract
Media from large vessel endothelial cells (pulmonary artery, aorta) contained intact connective tissue growth factor (CTGF) and a dominant 19-kDa band. N-terminal analysis of the 19-kDa band showed sequence corresponding to CTGF amino acid 181-190, suggesting that the 19-kDa band represented a proteolytic fragment of CTGF. Intact CTGF was increased by cAMP but not by transforming growth factor-beta (TGFbeta). CTGF messenger RNA (mRNA) was not changed by cAMP nor TGFbeta. In two microvessel endothelial cells, mRNA was found at low levels by PCR and Northern analysis, but no CTGF protein was seen on Western analysis. In the microvessel cells, TGFbeta increased and cAMP did not change CTGF mRNA levels, with neither TGFbeta nor cAMP increasing CTGF protein. The discordance between protein and mRNA levels in large vessel and microvessel endothelial cells was mostly explained by the effects of cAMP and TGFbeta on media proteolytic activity; in large vessel cells, cAMP inhibited degradation of CTGF, whereas in microvessel cells, TGFbeta and cAMP stimulated proteolytic activity against CTGF. We conclude that in large vessel endothelial cells, cAMP increased intact CTGF protein by inhibiting degradation of CTGF, whereas TGFbeta stimulated neither CTGF mRNA nor protein; in microvessel cells, TGFbeta increased CTGF mRNA, while both TGFbeta and cAMP stimulated CTGF degradation.
- Published
- 1999
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15. Transcriptional and posttranscriptional regulation of insulin-like growth factor binding protein-3 by cyclic adenosine 3',5'-monophosphate: messenger RNA stabilization is accompanied by decreased binding of a 42-kDa protein to a uridine-rich domain in the 3'-untranslated region.
- Author
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Erondu NE, Nwankwo J, Zhong Y, Boes M, Dake B, and Bar RS
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- Animals, Base Sequence, Binding Sites, Cattle, Cyclic AMP genetics, Cyclic AMP pharmacology, Cycloheximide pharmacology, Insulin-Like Growth Factor Binding Protein 3 drug effects, Molecular Sequence Data, Phosphoproteins metabolism, Protein Processing, Post-Translational, Protein Synthesis Inhibitors pharmacology, RNA, Messenger metabolism, Regulatory Sequences, Nucleic Acid, Transcription, Genetic, Uridine, 3' Untranslated Regions, Cyclic AMP metabolism, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 3 metabolism
- Abstract
The Madin Darby bovine kidney (MDBK) cell line was used to investigate the mechanisms underlying the cAMP regulation of insulin-like growth factor binding protein-3 (IGFBP-3) gene expression. Treatment of confluent monolayers either with forskolin or cAMP produced a 60- to 75-fold induction of IGFBP-3 mRNA and protein levels. This effect did not require new protein synthesis as inhibition of translation by cycloheximide actually caused a 2-fold increase in the cAMP induction. The rates of IGFBP-3 gene transcription, assessed by nuclear run-on assays, increased approximately 15-fold in cells exposed to cAMP. In addition, the half-life of the IGFBP-3 mRNA transcript was increased approximately 3-fold in the presence of cAMP. Gel mobility shift and competition experiments revealed the specific binding of an approximately 42-kDa cytoplasmic protein factor to the 3'-untranslated region (3'-UTR) of the IGFBP-3 mRNA. A 21-nucleotide uridine-rich segment that contained no AUUUA motif was sufficient for the specific binding. The binding activity of this protein was reduced after cAMP treatment but was increased by phosphatase treatment. In conclusion, the cAMP induction of IGFBP-3 mRNA in MDBK cells occurred at both the transcriptional and posttranscriptional levels. The IGFBP-3 mRNA stabilization in MDBK cells probably involved the phosphorylation of a member of the family of U-rich region mRNA-binding proteins and is the first reported member whose RNA-binding activity is reduced by cAMP.
- Published
- 1999
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16. Isolation and characterization of plasmin-generated bioactive fragments of IGFBP-3.
- Author
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Booth BA, Boes M, Dake BL, and Bar RS
- Subjects
- Amino Acid Sequence genetics, Animals, Cattle, Chromatography, High Pressure Liquid, Endothelium, Vascular cytology, Endothelium, Vascular metabolism, Glucose metabolism, Humans, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 3 physiology, Microcirculation physiology, Molecular Sequence Data, Peptide Fragments genetics, Peptide Fragments physiology, Recombinant Proteins, Fibrinolysin metabolism, Insulin-Like Growth Factor Binding Protein 3 biosynthesis, Insulin-Like Growth Factor Binding Protein 3 isolation & purification, Peptide Fragments biosynthesis, Peptide Fragments isolation & purification
- Abstract
Insulin-like growth factor-binding protein-3 (IGFBP-3) was digested with plasmin, and the proteolytic fragments were isolated by HPLC and tested for bioactivity as measured by stimulation of glucose uptake in microvessel endothelial cells. Two of the pooled fractions of the digest stimulated glucose uptake. The major bioactive pool, at an estimated protein concentration <50 ng/ml, stimulated glucose uptake to 150% of control with greater stimulation and 220% of control at approximately 250 ng/ml. Two fragments were present in the bioactive fraction, the dominant one migrating at approximately 20,000 and the other at approximately 8,000. Both fragments bound 125I-labeled insulin-like growth factor and [3H]heparin. NH2-terminal amino acid analysis of the bioactive peak yielded two sequences. One, representing the majority of the material, had an NH2-terminal sequence identical to IGFBP-3; the second fragment began at amino acid 202 of IGFBP-3. In contrast to the bioactive fragments, intact IGFBP-3, at concentrations up to 130 microgram/ml, had no bioactivity. These findings demonstrate that IGFBP-3 can be degraded into fragments that have potent bioactivities that are not present in the intact IGFBP-3 molecule.
- Published
- 1999
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17. Regulations of IGF binding proteins in human aorta vascular smooth muscle cells by cAMP, dexamethasone and IGF-I.
- Author
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Hayford K, Boes M, Dake BL, and Bar RS
- Subjects
- Aorta cytology, Cells, Cultured, Humans, Insulin-Like Growth Factor Binding Protein 3 drug effects, Insulin-Like Growth Factor Binding Protein 3 genetics, Insulin-Like Growth Factor Binding Protein 3 metabolism, Insulin-Like Growth Factor Binding Protein 4 drug effects, Insulin-Like Growth Factor Binding Protein 4 genetics, Insulin-Like Growth Factor Binding Protein 4 metabolism, Insulin-Like Growth Factor Binding Protein 6 drug effects, Insulin-Like Growth Factor Binding Protein 6 genetics, Insulin-Like Growth Factor Binding Protein 6 metabolism, Insulin-Like Growth Factor Binding Proteins drug effects, Insulin-Like Growth Factor Binding Proteins genetics, Metalloendopeptidases drug effects, Metalloendopeptidases metabolism, Muscle, Smooth, Vascular cytology, Muscle, Smooth, Vascular drug effects, Pregnancy-Associated Plasma Protein-A, Cyclic AMP pharmacology, Dexamethasone pharmacology, Insulin-Like Growth Factor Binding Proteins metabolism, Insulin-Like Growth Factor I pharmacology, Muscle, Smooth, Vascular metabolism
- Abstract
Human vascular smooth muscle cells produce IGFBP-3, IGFBP-4, IGFBP-6 and proteases specific for IGFBP-3 and IGFBP-4. This study evaluated the regulation of IGFBPs in human aorta smooth muscle cells by cyclic AMP, dexamethasone and IGF-I. cAMP decreased IGFBP-3, increased IGFBP-4 and increased IGFBP-6. Dexamethasone decreased IGFBP-3, slightly increased IGFBP-4 and increased IGFBP-6. IGF-I increased IGFBP-3 and IGFBP-6 while decreasing IGFBP-4. Co-incubation with IGF-I and dexamethasone or cAMP increased media IGFBP-3, despite a decrease in IGFBP-3 mRNA, due to the dominant effect of IGF-I-induced dissociation of cell surface-bound IGFBP-3. In cells incubated with cAMP and IGF-I, media IGFBP-4 was decreased, despite increased IGFBP-4 mRNA, in this case secondary to the dominant effect of IGF-I-stimulated IGFBP-4 protease. These findings suggest that cAMP, dexamethasone and IGF-I regulate IGFBP production in human aorta smooth muscle cells via a complex interplay of changes in transcription, protease activation and dissociation of cell surface-bound IGFBPs.
- Published
- 1998
- Full Text
- View/download PDF
18. Infused IGF-I/IGFBP-3 complex causes glomerular localization of IGF-I in the rat kidney.
- Author
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Sandra A, Boes M, Dake BL, Stokes JB, and Bar RS
- Subjects
- Animals, Autoradiography, Cross-Linking Reagents, Humans, Infusions, Intravenous, Insulin-Like Growth Factor Binding Protein 3 administration & dosage, Insulin-Like Growth Factor Binding Protein 4 pharmacokinetics, Insulin-Like Growth Factor I administration & dosage, Iodine Radioisotopes pharmacokinetics, Kidney Glomerulus cytology, Kidney Glomerulus ultrastructure, Kidney Tubules, Collecting cytology, Kidney Tubules, Collecting metabolism, Kidney Tubules, Collecting ultrastructure, Kidney Tubules, Distal cytology, Kidney Tubules, Distal metabolism, Kidney Tubules, Distal ultrastructure, Kidney Tubules, Proximal cytology, Kidney Tubules, Proximal metabolism, Kidney Tubules, Proximal ultrastructure, Protein Binding, Rats, Rats, Sprague-Dawley, Tissue Distribution, Insulin-Like Growth Factor Binding Protein 3 pharmacokinetics, Insulin-Like Growth Factor I pharmacokinetics, Kidney Glomerulus metabolism
- Abstract
Insulin-like growth factor I (IGF-I) increases renal blood flow, glomerular filtration rate (GFR), and proximal tubule reabsorption of phosphate in humans and rodents. The biological effects of IGF-I are likely to be influenced by cellular localization of IGF-I within the kidney. We therefore tested whether the renal localization of infused IGF-I could be altered if given with selected IGF-binding proteins (IGFBPs). Rats were treated with intravenous injections of 125I-labeled IGF-I, 125I-IGFBP-3, or 125I-IGFBP-4 alone or with complexes of 125I-IGF-I and IGFBP-3 or IGFBP-4. The cellular localization of IGF and the IGFBP within the kidney was then determined. 125I-IGF-I, 125I-IGFBP-4, and 125I-IGF-I/IGFBP-4 complexes were found almost exclusively in vacuolar structures (endosomes) of proximal renal tubules. In contrast, about one-third of renal 125I-IGFBP-3 and 125I-IGF-I/IGFBP-3 was localized to glomeruli. When 125I-IGF-I was given alone, 3% was found in glomeruli and 89% in proximal tubules. When given as 125I-IGF-I/IGFBP-3, 29% was in glomeruli and 65% in proximal tubules. We conclude that the cellular localization of IGF-I within the kidney can be directed to glomerular elements if the IGF-I is given with IGFBP-3.
- Published
- 1998
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19. Bovine insulin-like growth factor binding protein-3: organization of the chromosomal gene and functional analysis of its promoter.
- Author
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Erondu NE, Toland B, Boes M, Dake B, Moser DR, and Bar RS
- Subjects
- Animals, Base Sequence, Blotting, Southern, Cattle, DNA, Complementary metabolism, Humans, Molecular Sequence Data, RNA, Messenger biosynthesis, Sequence Homology, Nucleic Acid, Transcription, Genetic, Chromosome Mapping, Insulin-Like Growth Factor Binding Protein 3 genetics, Promoter Regions, Genetic
- Abstract
Insulin-like growth factor binding protein-3 (IGFBP-3), the major IGFBP in the circulation, is synthesized by the vascular endothelium in vivo and has been shown to be an important modulator of the physiological effects of IGF. IGFBP-3 is regulated by a number of growth factors/cytokines to which the vascular endothelium is exposed, including IGF-I stimulation and TGF-beta1 inhibition of IGFBP-3 in cultured endothelial cells. To understand the mechanisms of transcriptional regulation of IGFBP-3, we have cloned the bovine IGFBP-3 gene and begun the functional analysis of its promoter. Southern analysis indicated a single copy gene. The gene spanned approximately 10 kb and was divided into five exons, the fifth containing the 3' untranslated region. The transcription start site was 137 bp upstream of the initiation codon and a TATA box was located 26 bp 5' to this CAP site. No CAAT box was present but a GC rich sequence element, containing two overlapping putative AP-2 binding elements, was located 5' to the TATA box. Transient transfection studies with a series of 5' truncated luciferase reporter constructs were conducted in primary cultures of bovine aorta endothelial cells. Results of the transfection studies indicated that 1) nearly 80% of the maximal basal promoter activity was retained within the first 130 bp of the 5' flanking sequence; 2) this region responded to IGF-I, despite lacking the TTF-1/TTF-2 (thyroid specific transcription factors) binding elements that are required for IGF-I stimulation of thyroglobulin synthesis. These binding elements have also been suggested to be involved in IGF-I regulation of IGFBP-3 transcription, thus, implying the existence of novel cis-acting elements that mediate the IGF-I stimulation of bovine endothelial cell IGFBP-3 mRNA synthesis; 3) deletion of the GC rich sequence element resulted in a 60% reduction in basal promoter activity as well as loss of the IGF-1 stimulatory effect; 4) the TGF-beta1 mediated inhibition of IGFBP-3 transcription required sequence element(s) beyond 1.5 kb of its promoter.
- Published
- 1997
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20. Structure-function relationships in the heparin-binding C-terminal region of insulin-like growth factor binding protein-3.
- Author
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Booth BA, Boes M, Dake BL, Linhardt RJ, Caldwell EE, Weiler JM, and Bar RS
- Subjects
- Amino Acid Sequence, Animals, Antimetabolites metabolism, Cattle, Cells, Cultured, Deoxyglucose metabolism, Endothelium, Vascular metabolism, Extracellular Matrix metabolism, Fibroblast Growth Factors metabolism, Humans, Molecular Sequence Data, Recombinant Proteins pharmacology, Sequence Homology, Nucleic Acid, Structure-Activity Relationship, Anticoagulants metabolism, Heparin metabolism, Insulin-Like Growth Factor Binding Protein 3 metabolism
- Abstract
IGFBP-3 contains a carboxyterminal basic region which, when present as an isolated 18 amino acid peptide (P3), binds heparin, associates with cultured endothelial cells and stimulates glucose uptake. The P3 molecule has now been modified relative to charge, amino acid sequence and size to determine structure-function relationships relative to four properties of P3: affinity for heparin; inhibition of IGFBP-3 binding; stimulation of glucose uptake; and displacement of bFGF from the extracellular matrix of endothelial cells. Results indicate: (1) the presence or absence of heparin binding was concordant with the presence/absence of the other three properties; (2) the number of basic amino acids was an important, if not limiting, factor for each property; (3) the order of potency of the basic amino acids was arginine = lysine > > histidine; (4) the unrelated, basic protein, protamine, mimics all properties of P3; and (5) the putative consensus heparin-binding sequence of P3 was not essential for any of the P3 activities.
- Published
- 1996
21. Insulin-like growth factor binding protein production by bovine and human vascular smooth muscle cells: production of insulin-like growth factor binding protein-6 by human smooth muscle.
- Author
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Boes M, Booth BA, Dake BL, Moser DR, and Bar RS
- Subjects
- Animals, Aorta cytology, Aorta metabolism, Arteries cytology, Arteries metabolism, Cells, Cultured, Coronary Vessels cytology, Coronary Vessels metabolism, Humans, Insulin-Like Growth Factor Binding Proteins chemistry, Insulin-Like Growth Factor Binding Proteins genetics, Insulin-Like Growth Factor Binding Proteins metabolism, Molecular Weight, Muscle, Smooth, Vascular cytology, Polymerase Chain Reaction, Pulmonary Artery cytology, Pulmonary Artery metabolism, RNA, Messenger metabolism, Species Specificity, Transcription, Genetic, Cattle metabolism, Insulin-Like Growth Factor Binding Protein 6 biosynthesis, Insulin-Like Growth Factor Binding Proteins biosynthesis, Muscle, Smooth, Vascular metabolism
- Abstract
Insulin-like growth factor binding protein (IGFBP) secretory profiles were determined for vascular smooth muscle cells (VSMC) derived from bovine aorta and human aorta, pulmonary artery, and coronary artery. The bovine cells produced IGFBP-4, IGFBP-3, and an IGFBP-3 protease. IGF-I stimulated messenger RNA (mRNA) and media levels of IGFBP-3. The human cells produced IGFBP-3, IGFBP-4, and IGFBP-3 and IGFBP-4 proteases. The three human cells also produced a 30K IGFBP, shown to be IGFBP-6, based on increased affinity for IGF-II vs. IGF-I, size decrease when treated with O-glycanase, but not N-glycanase, reactivity with IGFBP-6 antiserum, presence of a 1.3-kilobase pair mRNA that hybridized to IGFBP-6 specific complementary DNA, and N-terminal amino acid sequence corresponding to IGFBP-6. In the human cells, IGF-I increased media levels of IGFBP-3 through stimulation of IGFBP-3 mRNA and dissociation of cell bound IGFBP-3, and decreased IGFBP-4 via potentiation of IGFBP-4 proteolysis. Neither the bovine nor the human aorta VSMC produced sufficient IGFBP-2 or IGFBP-2 mRNA to be detected by ligand blot and Northern analysis, as previously reported for porcine and rat aorta smooth muscle cells. The variable expression of IGFBPs and IGFBP proteases by VSMC are likely to contribute to differential vascular reactivity to the IGFs in larger arterial blood vessels.
- Published
- 1996
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22. Four- to twenty-four-hour uptake ratio: an index of rapid iodine-131 turnover in hyperthyroidism.
- Author
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Aktay R, Rezai K, Seabold JE, Bar RS, and Kirchner PT
- Subjects
- Adult, Female, Humans, Hyperthyroidism radiotherapy, Male, Radionuclide Imaging, Regression Analysis, Thyroid Gland metabolism, Time Factors, Treatment Failure, Hyperthyroidism diagnostic imaging, Iodine Radioisotopes pharmacokinetics, Iodine Radioisotopes therapeutic use, Thyroid Gland diagnostic imaging
- Abstract
Unlabelled: Rapid thyroidal iodine turnover may contribute to 131I therapy failure in patients with hyperthyroidism. The utility of a 4- to 24-hr 131I uptake ratio was evaluated as an index of thyroidal iodide retention in hyperthyroid patients., Methods: In 433 hyperthyroid patients, the success of 131I therapy was correlated with the following factors: gender, pretreatment with antithyroid drugs, clinical diagnosis, magnitude of early and late thyroidal 131I uptake values, and the 4- to 24-hr 131I uptake ratio., Results: Of the 433 patients, 362 patients (84%) had a successful outcome after a single therapeutic dose of 131I while 71 (16%) did not. Multiple linear regression analysis revealed that the highest statistically significant predictor of outcome was the 4- to 24-hr 131I uptake ratio (p-value < 0.001); all other factors showed a weaker association. An 131I uptake ratio of > 1 was found in 67 (15%) patients. Thirty-two of these 67 patients (48%) failed 131I therapy, whereas those patients with uptake ratios of < 1.0, only 39/366 (11%) failed 131I therapy., Conclusion: The 4- to 24-hr 131I thyroidal uptake ratio is a practical substitute for exact determination of the effective half-life. It identifies patients who are likely to have a rapid 131I turnover without the need for extended thyroid uptake measurements. An 131I uptake ratio of > or = 1 was found in 15% of hyperthyroid patients and was associated with a near 50% 131I therapy failure rate.
- Published
- 1996
23. IGFBP-3 proteolysis by plasmin, thrombin, serum: heparin binding, IGF binding, and structure of fragments.
- Author
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Booth BA, Boes M, and Bar RS
- Subjects
- Binding Sites, Blood, Female, Humans, Peptide Fragments, Pregnancy, Recombinant Proteins metabolism, Fibrinolysin metabolism, Heparin metabolism, Insulin-Like Growth Factor Binding Protein 3 metabolism, Insulin-Like Growth Factor I metabolism, Thrombin metabolism
- Abstract
Insulin-like growth factor binding protein (IGFBP)-3 was exposed to plasmin, thrombin, and pregnancy serum, substances normally present at the endothelial surface in enriched concentrations. The NH2-termini of the proteolytic fragments were sequenced, and their ability to bind insulin-like growth factor (IGF) and heparin was assessed by ligand blotting. Plasmin generated at least five fragments, three beginning at the NH2-terminus of IGFBP-3 and two with NH2-termini corresponding to middle portions of IGFBP-3. The dominant fragment bound both IGF and heparin while NH2-terminal fragments bound only IGF. Thrombin generated three and serum five easily identified fragments; the dominant fragments, beginning at midportions of IGFBP-3, retained IGF and heparin affinity, whereas the remaining fragments had differential affinities for IGF and heparin. We suggest that such fragments, when generated at the endothelia surface, have the potential to alter regional vascular concentrations of IGF and thus influence both IGF and endothelial function.
- Published
- 1996
- Full Text
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24. Regulation of endothelial IGFBP-3 synthesis and secretion by IGF-I and TGF-beta.
- Author
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Erondu NE, Dake BL, Moser DR, Lin M, Boes M, and Bar RS
- Subjects
- Adipose Tissue, Animals, Aorta, Base Sequence, Blotting, Northern, Cattle, Cells, Cultured, DNA Primers, Endothelium, Vascular drug effects, Gene Expression Regulation drug effects, Insulin-Like Growth Factor I analogs & derivatives, Insulin-Like Growth Factor I metabolism, Molecular Sequence Data, Polymerase Chain Reaction, RNA, Messenger analysis, RNA, Messenger biosynthesis, Receptor, IGF Type 1 drug effects, Receptor, IGF Type 1 physiology, Endothelium, Vascular metabolism, Insulin-Like Growth Factor Binding Protein 3 biosynthesis, Insulin-Like Growth Factor I pharmacology, Transcription, Genetic drug effects, Transforming Growth Factor beta pharmacology
- Abstract
We have examined the regulation of endothelial IGFBP-3 production by IGF-I and TGF-beta, two growth factors thought to play a major roles in the complications of diabetes mellitus. In addition, we developed a sensitive method for IGFBP-3 mRNA quantitation by adapting the fluorescent modification of the competitive PCR strategy. Our results using both Northern analysis and the fluorescent competitive PCR method indicate that: (1) IGFBP-3 mRNA is increased 2- to 10-fold by IGF-I and maximally reduced to 20% of control by TGF-beta; (2) the changes in mRNA levels correlate with the levels of IGFBP-3 protein secreted into the media by these cells; (3) the induction of IGFBP-3 mRNA and protein by IGF-I analogs was directly related to their ability to bind to the type I IGF receptor, reflecting an IGF-I receptor-mediated process; and (4) steady state IGFBP-3 mRNA levels did not change significantly after a 6 h incubation with actinomycin D in the presence or absence of the growth factors suggesting that the observed IGF-I/TGF-beta effects occur at the level of gene transcription rather than mRNA stability.
- Published
- 1996
25. Endothelial cells express insulin-like growth factor-binding proteins 2 to 6.
- Author
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Moser DR, Lowe WL Jr, Dake BL, Booth BA, Boes M, Clemmons DR, and Bar RS
- Subjects
- Adipose Tissue, Amino Acid Sequence, Animals, Aorta, Base Sequence, Cattle, Cells, Cultured, DNA genetics, Endothelium cytology, Endothelium, Vascular cytology, Endothelium, Vascular metabolism, Humans, Insulin-Like Growth Factor Binding Proteins, Molecular Sequence Data, Organ Specificity, Pulmonary Artery, RNA, Messenger biosynthesis, Rats, Sequence Alignment, Sequence Homology, Amino Acid, Species Specificity, Carrier Proteins biosynthesis, Endothelium metabolism
- Abstract
Cultured endothelial cells have been shown to produce insulin-like growth factor-binding proteins (IGFBPs); however, the identity of these BPs has not been defined. We now demonstrate that cultured bovine endothelial cells produce IGFBP2, IGFBP3, and IGFBP4 and have mRNA specific for IGFBP2, -3, -4, -5 and -6. DNA probes for bovine IGFBP2-6 were obtained by polymerase chain reaction (PCR) amplification of cDNA from bovine large vessel pulmonary artery and aortic endothelial cells as well as omental and periaortic fat microvessel cells, using oligonucleotide primers whose sequences were based on the reported cDNA sequences of IGFBP2-6. The PCR-derived probes were labeled with 32P and used for Northern blot analysis of RNAs obtained from the four bovine endothelial cell types. Transcripts corresponding to IGFBP2-6 were found in RNA from large vessel endothelial cells (bovine pulmonary artery and bovine aorta) and microvessel cells (periaortic and omental fat). The PCR-derived probe for IGFBP4 was used to screen a bovine pulmonary artery cDNA library for a full-length bovine IGFBP4 cDNA clone. One positive clone, containing a single EcoRI insert of approximately 2.0 kilobases, was selected for further characterization by DNA sequence analysis. This clone contained an open reading frame encoding a 258-amino acid protein that was 97% identical to human IGFBP4, 268 basepairs of 5'-untranslated region, and a longer 1044 basepairs of 3'-untranslated region. IGFBP4 protein was purified from bovine pulmonary artery-conditioned medium, shown to have N-terminal amino acid sequence DEAIHCPPCSEEKLARCR (identical to human IGFBP4) and to be secreted in glycosylated and nonglycosylated forms. Immunoblots further demonstrated that microvessel cells, at early passage, secrete predominantly IGFBP2 and IGFBP3, while large vessel cells, at early and late passages, secrete IGFBP3 and IGFBP4. Thus, cultured bovine endothelial cells synthesize and secrete IGFBP2, IGFBP3, and IGFBP4 and have mRNA encoding IGFBP2-6. The production of specific IGFBPs by endothelial cells raises the interesting possibility that the vascular endothelium contributes to circulating and tissue levels of specific IGFBPs in vivo.
- Published
- 1992
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26. Insulin-like growth factor binding protein (IGFBP)4 accounts for the connective tissue distribution of endothelial cell IGFBPs perfused through the isolated heart.
- Author
-
Boes M, Booth BA, Sandra A, Dake BL, Bergold A, and Bar RS
- Subjects
- Amino Acid Sequence, Animals, Carrier Proteins chemistry, Carrier Proteins isolation & purification, Cattle, Cells, Cultured, Chromatography, Culture Media, Glycosylation, Insulin-Like Growth Factor Binding Protein 4, Molecular Sequence Data, Pulmonary Artery metabolism, Carrier Proteins metabolism, Connective Tissue metabolism, Endothelium, Vascular metabolism, Myocardium metabolism
- Abstract
Insulin-like growth factor binding protein 4 (IGFBP4) was purified to homogeneity from conditioned media of bovine pulmonary artery endothelial cells and shown to have the N-terminal amino acid sequence DEAIHCPPCS, a sequence unique to IGFBP4. The IGFBP4 was separated into predominantly glycosylated and nonglycosylated fractions, with each fraction separately perfused through isolated, beating rat hearts. Both forms of IGFBP4 crossed the capillary boundary of the heart and distributed primarily in subendothelial connective tissue components with a connective tissue/cardiac muscle distribution ratio of 20:1 for the glycosylated fraction and 27:1 for the nonglycosylated fraction. Perfused IGFBP1, 2, 3, and IGF-I also crossed the capillary boundary but in contrast to IGFBP4, preferentially localized in cardiac muscle with a connective tissue/muscle ratio of approximately 1:3. We conclude that the connective tissue distribution previously reported for IGFBPs in conditioned media of pulmonary artery endothelial cells is due to IGFBP4.
- Published
- 1992
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27. Interactions of cultured endothelial cells with TGF-beta, bFGF, PDGF and IGF-I.
- Author
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Boes M, Dake BL, and Bar RS
- Subjects
- Animals, Cattle, Cells, Cultured, Down-Regulation, Endothelium cytology, Fibroblast Growth Factors metabolism, Insulin-Like Growth Factor I metabolism, Platelet-Derived Growth Factor metabolism, Transforming Growth Factors metabolism, Endothelium metabolism, Growth Substances metabolism
- Abstract
Endothelial cells in culture synthesize the growth factors transforming growth factor beta (TGF-beta), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF) and, perhaps, insulin like growth factor I (IGF-I). We have previously demonstrated that IGF-I and PDGF have both high affinity receptors and stimulate glucose and AIB uptake in the microvessel cells under study and that IGF-I, but not PDGF, has similar high affinity receptors in cultured large vessel endothelial cells. In the present study, cultured bovine endothelial cells were exposed to these four growth factors to determine a) their effects on the acute metabolic processes of neutral amino acid (AIB) and glucose uptake and b) their interactions at the endothelial cell surface. In microvessel endothelial cells, each growth factor stimulated AIB and glucose uptake 2-4 fold whereas in large vessel endothelial cells only bFGF stimulated glucose uptake. Each growth factor had specific high affinity binding to the microvessel cells that was not influenced by the presence of the other growth factors. In large vessel endothelial cells, similar high affinity binding was present only for IGF-I and to a lesser degree TGF-beta. When cells were exposed to a given growth factor for 18 hours, homologous receptor downregulation was observed, with a maximal 60-95% decrease in surface binding. These findings suggest several potential levels of interaction of the growth factors TGF-beta, bFGF, PDGF and IGF-I in cultured vascular endothelial cells.
- Published
- 1991
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28. Intrinsic bioactivity of insulin-like growth factor-binding proteins from vascular endothelial cells.
- Author
-
Booth BA, Bar RS, Boes M, Dake BL, Bayne M, and Cascieri M
- Subjects
- Aminoisobutyric Acids metabolism, Animals, Aorta, Cattle, Cells, Cultured, Chromatography, Affinity, Deoxyglucose metabolism, Genes, Synthetic, Humans, Insulin-Like Growth Factor I genetics, Kinetics, Receptors, Cell Surface isolation & purification, Receptors, Somatomedin, Endothelium, Vascular metabolism, Insulin-Like Growth Factor I metabolism, Receptors, Cell Surface metabolism
- Abstract
Conditioned medium from cultured vascular endothelial cells contains material capable of stimulating acute metabolic processes in endothelial cells. The bioactivity of the conditioned medium is not caused by the copurification of known growth factors produced by the cells, in particular platelet-derived growth factor, basic fibroblast growth factor, or insulin-like growth factor (IGF)-I/II. We now demonstrate that the bioactivity is directly due to an IGF-binding protein(s) (ECBP) and, further, that the bioactive domain of the binding protein differs from the IGF-binding domain. Binding proteins (BPs) from cultured pulmonary artery endothelial cells were purified by sequential passage over sizing, multiplication-stimulating activity affinity, and hydrophobic columns. BP fractions were separated into those with and those without biological activity. The bioactive binding protein(s) was cross-linked with disuccinimidyl suberate to IGF-I or the recombinant IGF analog [1-27,Gly4,38-70]IGF-I (Analog). The IGF-I Analog, by itself, had minimal interaction with the type I IGF receptor in cultured microvessel endothelial cells and no intrinsic bioactivity, but did bind with high affinity to ECBP. All free BP and free IGF-I/Analog were removed from the cross-linked mixture by passage over gel filtration and IGF affinity columns. The cross-linked BP-IGF-I complex did not bind to the type I receptor of cultured endothelial cells, but did stimulate glucose and alpha-aminoisobutyric acid uptake in endothelial cells (approximately 2-fold increase); the magnitude of the response was nearly equal to the effect of ECBP or IGF-I alone. The BP-Analog complex also stimulated glucose and alpha-aminoisobutyric acid uptake, with the magnitude of the response approaching the effect of ECBP alone. The BP-Analog complex also did not react with type I IGF receptors on the cultured endothelial cells. We conclude 1) IGF-BP produced by endothelial cells possess intrinsic biological activity; 2) bioactivity of the BP(s) is retained when the IGF-binding domain of the BP is occupied by IGF-I or an inactive IGF-I analog; and 3) IGF-I bound to the bioactive BP does not react with its receptor and possesses minimal, if any, bioactivity in vitro.
- Published
- 1990
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29. Tissue localization of perfused endothelial cell IGF binding protein is markedly altered by association with IGF-I.
- Author
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Bar RS, Boes M, Dake BL, Sandra A, Bayne M, Cascieri M, and Booth BA
- Subjects
- Animals, Autoradiography, Carrier Proteins isolation & purification, Cross-Linking Reagents metabolism, Insulin-Like Growth Factor I analogs & derivatives, Insulin-Like Growth Factor I metabolism, Iodine Radioisotopes, Male, Molecular Weight, Pulmonary Artery, Rats, Rats, Inbred Strains, Receptors, Cell Surface isolation & purification, Receptors, Somatomedin, Connective Tissue metabolism, Endothelium, Vascular metabolism, Insulin-Like Growth Factor I pharmacology, Myocardium metabolism, Receptors, Cell Surface metabolism
- Abstract
Perfused endothelial cell IGF binding proteins (ECBP) have been previously demonstrated to leave the microcirculation of the rat heart and distribute primarily in connective tissue elements of the heart. In the present study, ECBP have been crosslinked to IGF-I and the biologically inactive [1-27,gly4,38-70]-hlGF-I, an analog of IGF-I lacking the type I IGF receptor domain. The crosslinked ECBPs were perfused through the isolated rat heart and their tissue distributions determined. Both [ECBP-Analog] and [ECBP-IGF-I] left the microcirculation of the heart. [ECBP-Analog] preferentially localized in connective tissue elements with a muscle:connective tissue ratio of approximately 1:6, similar to the tissue distribution of perfused ECBP. In contrast, the [ECBP-IGF-I] complexes localized in cardiac muscle with a muscle to connective tissue ratio of approximately 3:1, virtually identical to the tissue distribution of IGF-I when the IGF-I is perfused through the heart in the absence of any binding proteins. We conclude that 1) ECBP in the presence of IGF will cross capillary boundaries and 2) the tissue distribution of [ECBP-IGF-I] is dictated by the IGF-I molecule.
- Published
- 1990
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30. Transcapillary permeability and subendothelial distribution of endothelial and amniotic fluid insulin-like growth factor binding proteins in the rat heart.
- Author
-
Bar RS, Clemmons DR, Boes M, Busby WH, Booth BA, Dake BL, and Sandra A
- Subjects
- Animals, Cattle, Connective Tissue metabolism, Coronary Vessels metabolism, Humans, Immunohistochemistry, Insulin-Like Growth Factor Binding Proteins, Iodine Radioisotopes, Male, Rats, Amniotic Fluid analysis, Capillary Permeability, Carrier Proteins metabolism, Endothelium, Vascular metabolism, Myocardium metabolism
- Abstract
Insulin-like growth factor (IGF) binding proteins (IGFBP) were purified from conditioned media of cultured bovine endothelial cells (ECBP) and from human amniotic fluid (IGFBP-1), and then labeled by radioiodination. 125I-ECBP and 125I-IGFBP-1 were perfused through isolated beating rat hearts for 1 and 5 min, and the hearts fixed and analyzed for 125I-BP content and distribution. One to 4% of the perfused 125I-ECBP and 125I-IGFBP-1 crossed the capillary boundary. The ECBPs predominantly localized as intact 125I-BP in connective tissue elements of the heart with less 125I-BP in cardiac muscle. The ratio of 125I-ECBP in connective tissue: muscle (normalized to percent vol of these compartments) was greater than or equal to 10:1. In contrast, the IGFBP-1 had a greater affinity for cardiac muscle with ratios of 125I-IGFBP-1 in connective tissue:muscle of approximately 1:2. When 125I-IGF-I, in the absence of any BPs, was perfused through the hearts approximately 3-5% left the microcirculation and was found in subendothelial tissues. 125I-IGF-I localized primarily to cardiac muscle with a distribution of connective tissue:cardiac muscle of about 1:3. The findings in the isolated perfused heart were confirmed in intact animals. After 125I-IGFBP-1 was injected into anesthetized rats and allowed to circulate for 5 min, substantial radioactivity was associated with the heart. As in the isolated heart, the IGFBP-1 preferentially localized to cardiac muscle with a connective tissue:cardiac muscle ratio of 1:3. We conclude that IGFBPs produced by endothelial cells and the IGFBP-1 contained in amniotic fluid can cross the capillary boundaries of the rat heart, and that the ECBPs preferentially localize in connective tissue elements of the myocardium, whereas IGFBP-1 predominantly localizes in cardiac muscle.
- Published
- 1990
- Full Text
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31. Insulin differentially alters transcapillary movement of intravascular IGFBP-1, IGFBP-2 and endothelial cell IGF-binding proteins in the rat heart.
- Author
-
Bar RS, Boes M, Clemmons DR, Busby WH, Sandra A, Dake BL, and Booth BA
- Subjects
- Animals, Capillaries metabolism, Coronary Vessels drug effects, Endothelium, Vascular drug effects, Heart drug effects, Humans, Insulin-Like Growth Factor Binding Proteins, Rats, Carrier Proteins metabolism, Coronary Vessels metabolism, Endothelium, Vascular metabolism, Insulin pharmacology, Myocardium metabolism
- Abstract
Insulin-like growth factor binding-proteins 1 and 2 (IGFBP-1, IGFBP-2) and endothelial cell IGF binding proteins (ECBP) were individually perfused through isolated beating rat hearts in the absence and presence of insulin. Insulin caused an increased movement of IGFBP-1 from the vascular space to tissues of the heart. Subendothelial content of IGFBP-1 was 110%, 126% (p less than .01) and 132% (p less than 0.05) of control hearts when perfused with 1, 10 and 100 ng/ml insulin, respectively. . In contrast, insulin treatment was associated with a decrease in ECBP content in cardiac tissue, being 83%, 62% (p less than 0.005) and 73% (p less than 0.05) of control when perfused with 1, 10 and 100 ng/ml insulin. The efflux of IGFBP-2 from the intravascular space was unaffected by insulin. The subendothelial tissue distribution of the transported binding proteins was not changed by insulin perfusion, with IGFBP-1 and IGFBP-2 localizing predominantly in cardiac muscle and ECBP having greater affinity for connective tissue elements. We conclude that in the perfused rat heart, insulin can differentially alter transcapillary movement of IGFBP-1, IGFBP-2 and endothelial cell IGF-binding proteins. Such insulin-facilitated changes could potentially mediate nutrient-dependent transport of IGF-I and IGF-II to peripheral tissues.
- Published
- 1990
- Full Text
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32. Primary amenorrhea associated with hirsutism, acanthosis nigricans, dermoid cysts of the ovaries and a new type of insulin resistance.
- Author
-
Imperato-McGinley J, Peterson RE, Sturla E, Dawood Y, and Bar RS
- Subjects
- Adolescent, Androstenedione metabolism, Dermoid Cyst diagnosis, Dermoid Cyst physiopathology, Female, Humans, Ovarian Neoplasms diagnosis, Ovarian Neoplasms physiopathology, Ovary physiopathology, Testosterone metabolism, Acanthosis Nigricans etiology, Amenorrhea etiology, Dermoid Cyst complications, Hirsutism etiology, Insulin Resistance, Ovarian Neoplasms complications
- Abstract
We describe a 15 1/2 year old presenting with primary amenorrhea, hirsutism, acanthosis nigricans and insulin resistance. Ovarian vein catheterization studies revealed bilateral excess plasma testosterone and androstenedione secretion, and at surgery multiple dermoid cysts of both ovaries were found in association with polycystic ovaries. The suggestion that the dermoid cysts may be causative in the evolution of the polycystic ovarian disease has been made. The mechanism of the insulin resistance appears to be at the post receptor level. The acanthosis nigricans diminished following surgery with normalization of the plasma androgens.
- Published
- 1978
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33. Change in affinity of insulin receptors following oral glucose in normal adults.
- Author
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Muggeo M, Bar RS, and Roth J
- Subjects
- Adult, Blood Cells metabolism, Female, Humans, Male, Monocytes, Protein Binding, Glucose pharmacology, Receptor, Insulin metabolism
- Abstract
125I-insulin binding to circulating monocytes has been studied in 4 normal volunteers in the basal state as well as at 2 and 5 hours after ingestion of 100 g of glucose. In each study five hours after glucose ingestion, the competition-inhibition curve was shifted to the left and was steeper than that in the basal study; the amount of insulin that caused a 50% decrease in specific binding of 125I-insulin in the basal study was 3-11 fold higher than at 5 hours after glucose. These changes in binding after glucose ingestion were largely due to major alterations of receptor affinity. We conclude that acute changes in receptor affinity occur normally as part of the physiologic regulation of target cell sensitivity to hormonal stimulation.
- Published
- 1977
- Full Text
- View/download PDF
34. Antibodies that impair insulin receptor binding in an unusual diabetic syndrome with severe insulin resistance.
- Author
-
Flier JS, Kahn CR, Roth J, and Bar RS
- Subjects
- Animals, Antigen-Antibody Reactions, Binding Sites, Diabetes Mellitus metabolism, Erythrocytes metabolism, Female, Humans, Liver metabolism, Lymphocytes metabolism, Monocytes immunology, Monocytes metabolism, Rats, Syndrome, Autoantibodies, Diabetes Mellitus immunology, Insulin metabolism, Insulin Resistance, Receptors, Cell Surface
- Abstract
Six patients with a unique form of diabetes associated with extreme insulin resistance have markedly reduced insulin binding to specific receptors on their circulating monocytes. When normal insulin receptors were exposed to serum or immunoglobulin fractions from three of these patients in vitro the specific binding defect was reproduced.
- Published
- 1975
- Full Text
- View/download PDF
35. Characterization of insulin receptors in patients with the syndromes of insulin resistance and acanthosis nigricans.
- Author
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Bar RS, Muggeo M, Kahn CR, Gorden P, and Roth J
- Subjects
- Acanthosis Nigricans complications, Adolescent, Adult, Binding, Competitive, Diabetes Complications, Diabetes Mellitus drug therapy, Female, Humans, Insulin blood, Insulin therapeutic use, Kinetics, Male, Middle Aged, Monocytes metabolism, Acanthosis Nigricans blood, Diabetes Mellitus blood, Insulin Resistance, Receptor, Insulin metabolism
- Abstract
This report analyzes the in vitro characteristics of 125I-insulin binding to the monocytes of nine patients with the syndromes of acanthosis nigricans and insulin resistance. The 3 Type A patients (without demonstrable autoantibodies to the insulin receptor) had decreased binding of insulin due to a decreased concentration of receptors. In these patients the residual receptors demonstrated normal dissociation kinetics, negative cooperativity, and were blocked by anti-receptor antibodies in a manner similar to normal cells. In contrast, monocytes from the 6 Type B patients (with circulating anti-receptor autoantibodies) had decreased binding of insulin due to a decrease in receptor affinity. Insulin binding to monocytes of Type B patients demonstrated accelerated rates of dissociation with no evidence of cooperative interactions among insulin receptors. When coupled with previous data, the present studies further suggest that different mechanisms account for the defects in insulin binding and insulin resistance observed in these patients.
- Published
- 1980
- Full Text
- View/download PDF
36. Interactions of insulin with bovine endothelium.
- Author
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Peacock ML, Bar RS, and Goldsmith J
- Subjects
- Animals, Cattle, Endothelium metabolism, Humans, Insulin analogs & derivatives, Proinsulin metabolism, Temperature, Umbilicus metabolism, Aorta metabolism, Insulin metabolism, Pulmonary Artery metabolism, Pulmonary Veins metabolism
- Abstract
Bovine endothelial cells have been isolated from pulmonary and systemic vessels and grown in culture as primary, passaged and passaged cloned-strains. The cultures were shown to be endothelial in nature on the basis of several endothelial-specific and endothelial-associated traits. Endothelial cells from all sources had specific receptors for insulin in primary culture and after serial passage. Endothelial cells derived from pulmonary arteries and aortas bound 2.5 times more insulin than cells derived from the pulmonary vein. Each endothelial cell type maintained a specific complement of receptors through at least 25 passages in vitro. Coupled with previous findings of insulin receptors on endothelial cells from human umbilical vessels, these data suggest that insulin receptors may be an intrinsic component of all vascular endothelium.
- Published
- 1982
37. Effects of membrane lipid unsaturation on the interactions of insulin and multiplication stimulating activity with endothelial cells.
- Author
-
Bar RS, Dolash S, Spector AA, Kaduce TL, and Figard PH
- Subjects
- Animals, Cattle, Cells, Cultured, Fatty Acids, Unsaturated metabolism, Female, Insulin metabolism, Insulin-Like Growth Factor II, Male, Membrane Fluidity, Phospholipids physiology, Receptor, Insulin metabolism, Endothelium drug effects, Insulin pharmacology, Membrane Lipids physiology, Peptides pharmacology, Somatomedins pharmacology
- Abstract
Modification of plasma membrane fatty acyl composition has resulted in major changes in insulin binding and insulin action in several cell types. In the present study, endothelial cells, which in vivo are directly bathed by the changing fatty acid and insulin environment of the bloodstream, were grown in media enriched in specific saturated, monounsaturated and polyunsaturated fatty acids. These media conditions resulted in major and specific alteration in fatty acyl unsaturation of both neutral lipids and phospholipids of the endothelial cells. Despite the extensive fatty acyl changes, the lipid-modified cells demonstrated no change in the binding of insulin or the insulin-like growth factor, multiplication stimulating activity, and little alteration in insulin-induced down-regulation of the insulin receptor, or in cell processing of insulin. We suggest that the insulin receptor of the endothelial cell responds in a different manner than other cell types to similar alterations of membrane fatty acyl composition.
- Published
- 1984
- Full Text
- View/download PDF
38. Insulin receptors in patients with insulinomas: changes in receptor affinity and concentration.
- Author
-
Bar RS, Gorden P, Roth J, and Siebert CW
- Subjects
- Blood Cells metabolism, Female, Humans, Insulin metabolism, Male, Monocytes, Protein Binding, Adenoma, Islet Cell metabolism, Receptor, Insulin metabolism
- Abstract
We have measured the specific binding of 125I-insulin to insulin receptors on circulating monocytes from 5 patients with insulinomas. In all patients the concentration of insulin receptors was inversely related to the basal, circulating level of insulin (corrected for proinsulin content). In the four patients with chronically elevated concentrations of plasma insulin, receptor concentrations were decreased. In three of these patients there were also marked alterations in receptor affinity. With insulinomas, correlations with the clinical state appear to be clearer when receptor concentration and especially receptor affinity are considered in addition to circulating insulin and proinsulin levels.
- Published
- 1977
- Full Text
- View/download PDF
39. Insulin receptor status in disease states of man.
- Author
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Bar RS and Roth J
- Subjects
- Acanthosis Nigricans metabolism, Adenoma, Islet Cell metabolism, Adipose Tissue metabolism, Animals, Ataxia Telangiectasia metabolism, Binding Sites, Diabetes Mellitus metabolism, Humans, Hyperinsulinism metabolism, Insulin metabolism, Insulin Resistance, Monocytes metabolism, Obesity metabolism, Pancreatic Neoplasms metabolism, Receptor, Insulin metabolism
- Abstract
When insulin or any peptide hormone binds to its receptor on the surface of a target cell, it initiates a series of biochemical steps that ultimately lead to the characteristic action of the hormone. The strength of the signal generated by the hormone depends equally on the hormone concentration, the receptor concentration, and the receptor affinity. Not only do hormone concentrations change rapidly and widely in vivo but so do receptor concentration and affinity. In hormone resistant states, any step in the biochemical pathway of hormone action at the target cell may be involved. Studies of insulin receptors in people indicate that the insulin receptor is altered in many common disorders such as obesity and diabetes, as well as in rare disorders such as extreme insulin resistance due to circulating antibodies directed at the insulin receptor itself. By responding to both intracellular and extracellular events, the insulin receptor is, therefore, a major site for the regulation of target cell responsiveness in vivo.
- Published
- 1977
40. Receptors for multiplication-stimulating activity on human arterial and venous endothelial cells.
- Author
-
Bar RS, Peacock ML, Rechler MM, and Nissley SP
- Subjects
- Binding, Competitive, Endothelium metabolism, Female, Humans, Insulin metabolism, Insulin-Like Growth Factor II, Kinetics, Mitogens metabolism, Pregnancy, Receptors, Somatomedin, Peptides metabolism, Receptors, Cell Surface metabolism, Umbilical Arteries metabolism, Umbilical Veins metabolism
- Abstract
Primary cultures of endothelial cells were prepared from the arteries and veins of human umbilical cords. Both arterial and venous endothelial cells demonstrated specific receptors for the insulin-like growth factor MSA (Multiplication-Stimulating Activity). Insulin, at concentrations up to 10(-7) M, had little effect on 125I-MSA binding whereas MSA was congruent to 1% as potent as insulin in competing with 125I-insulin binding. Serum containing anti-insulin receptor antibodies blocked binding of 125I-insulin to the endothelial cells but had little effect on 125I-MSA binding. We conclude that human endothelial cells have specific and distinct receptors for both MSA and insulin.
- Published
- 1981
- Full Text
- View/download PDF
41. Rapid transport of biologically intact insulin through cultured endothelial cells.
- Author
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Dernovsek KD, Bar RS, Ginsberg BH, and Lioubin MN
- Subjects
- Animals, Biological Transport, Cattle, Cells, Cultured, Endothelium metabolism, Kinetics, Pulmonary Artery metabolism, Blood Vessels metabolism, Insulin metabolism
- Abstract
Mono A14-[125I]-iodoinsulin was incubated with cultured endothelial cells derived from bovine pulmonary arteries at physiologic conditions. The processing of the cell-bound A14-[125I]-iodoinsulin was evaluated by trichloroacetic acid precipitation, gel filtration and high performance liquid chromatography. In contrast to insulin processing in many other cell types, approximately 95% of cell bound insulin was dissociated from the cells in less than 15 minutes, and biologically intact insulin rapidly passed through the endothelial cells. The unique location of endothelial cells coupled with the ability of rapid transport of intact insulin are consistent with an endothelial role for either the transport of insulin out of the bloodstream or as an extra-pancreatic storage area for insulin.
- Published
- 1984
- Full Text
- View/download PDF
42. Stimulation of proteoglycans by IGF I and II in microvessel and large vessel endothelial cells.
- Author
-
Bar RS, Dake BL, and Stueck S
- Subjects
- Animals, Aorta cytology, Capillaries cytology, Cells, Cultured, Endothelium cytology, Endothelium metabolism, Glycosaminoglycans metabolism, Insulin metabolism, Insulin pharmacology, Insulin-Like Growth Factor II metabolism, Proteoglycans biosynthesis, Pulmonary Artery cytology, Stimulation, Chemical, Aorta metabolism, Capillaries metabolism, Insulin-Like Growth Factor II pharmacology, Proteoglycans metabolism, Pulmonary Artery metabolism, Somatomedins pharmacology
- Abstract
Endothelial cells were cultured from bovine capillaries and pulmonary arteries, and the effect of insulinlike growth factor (IGF) I and II (multiplication-stimulating activity) and insulin on the synthesis of proteoglycans was determined. IGF I and II stimulated 35SO4 incorporation into proteoglycans in a dose-dependent manner in both microvessel and pulmonary artery endothelial cells with maximum threefold increases. In pulmonary artery cells, the IGFs caused a general stimulation of all classes of glycosaminoglycan-containing proteoglycans. In microvessel endothelial cells, the IGFs appeared to preferentially increase heparan sulfate-containing proteoglycans. Insulin, at concentrations up to 10(-6) M, had no effect on the synthesis of proteoglycans in either microvessel or pulmonary arterial endothelial cells. Thus, the IGFs stimulate the synthesis of proteoglycans in both microvessel and large vessel endothelial cells, a property that is not mimicked by insulin. Because vascular endothelial cells are bathed by IGFs in vivo, such IGF-mediated functions are likely to be significant in both the normal physiology of vascular endothelium and in disease states such as diabetes mellitus.
- Published
- 1987
- Full Text
- View/download PDF
43. Factors that control insulin action at the receptor.
- Author
-
Bar RS
- Subjects
- Autoantibodies, Cell Membrane metabolism, Diabetes Mellitus metabolism, Humans, Insulin Resistance, Phosphoenolpyruvate Carboxykinase (GTP) metabolism, Receptor, Insulin immunology, Insulin metabolism, Receptor, Insulin metabolism
- Abstract
The binding of insulin to its plasma membrane receptors is an important component of insulin action at the cellular level. Insulin binding is altered in a number of clinical disease states in humans, and several specific regulators of the receptor have been identified. Recent in vitro studies of receptor regulators have furthered our understanding of the interaction of insulin with its receptors and also increased our awareness of the complexity of this interaction. The importance of the plasma membrane environment around the receptor, the potential importance of receptor microaggregation to information transfer, and the coupling of receptor binding to insulin action are reviewed.
- Published
- 1983
- Full Text
- View/download PDF
44. Multiplication-stimulating activity (MSA) stimulates proteoglycan synthesis in cultured endothelial cells.
- Author
-
Bar RS, Stueck S, Dake B, and Spanheimer R
- Subjects
- Animals, Cattle, Cells, Cultured, Dose-Response Relationship, Drug, Endothelium cytology, Endothelium metabolism, Insulin pharmacology, Insulin-Like Growth Factor II, Pulmonary Artery cytology, Stimulation, Chemical, Time Factors, Peptides pharmacology, Proteoglycans biosynthesis, Pulmonary Artery metabolism
- Abstract
Cultured endothelial cells have previously been shown to have specific binding sites for certain insulin-like growth factors (IGFs) and insulin. In the present study, the IGF, Multiplication Stimulating Activity (MSA), at concentrations of 100-1000 ng/ml, stimulated 35SO4 incorporation into proteoglycans by endothelial cells cultured from bovine pulmonary arteries. The stimulatory effect on proteoglycan synthesis was not accompanied by changes in cell number, total protein synthesis, nor collagen synthesis and was not mimicked by insulin. These findings suggest that MSA specifically stimulated accumulation of proteoglycans in the cultured endothelial cells, with the effect mediated through an IGF receptor.
- Published
- 1984
- Full Text
- View/download PDF
45. IGF receptors in myocardial capillary endothelium: potential regulation of IGF-I transport to cardiac muscle.
- Author
-
Bar RS, Boes M, and Sandra A
- Subjects
- Animals, Capillaries metabolism, Cells, Cultured, Coronary Vessels metabolism, In Vitro Techniques, Kinetics, Rats, Receptors, Somatomedin, Endothelium, Vascular metabolism, Insulin-Like Growth Factor I metabolism, Myocardium metabolism, Receptor, Insulin metabolism, Somatomedins metabolism
- Abstract
Beating rat hearts were perfused with 125I-IGF-II alone or 125I-IGF-II and unlabeled IGF-II or insulin, then prepared for radioautography. Maximal 125I-IGF-II grain counts over capillaries were decreased in a dose-dependent manner by unlabeled IGF-II but were unaffected by coperfusion with insulin. To determine a potential role for capillary receptors in the transfer of circulating IGF to cardiac muscle, the effects of sequential loss of capillary IGF binding sites was determined. For IGF-I, loss of capillary binding sites by trypsin perfusion was accompanied by proportional decreases in the subsequent appearance of IGF-I in cardiac muscle. In contrast, similar decrements of capillary IGF-II binding did not affect muscle levels of IGF-II. We conclude that capillary endothelium of the intact heart possesses distinct IGF-I and IGF-II binding sites, with the capillary IGF-I binding sites being of potential importance in the transfer of vascular IGF-I to subendothelial cardiac muscle.
- Published
- 1988
- Full Text
- View/download PDF
46. Morphological alterations in cultured endothelial cells induced by arachidonic acid.
- Author
-
Sandra A, Bar RS, Dolash S, Marshall SJ, Kaduce TL, and Spector AA
- Subjects
- Animals, Aorta cytology, Arachidonic Acid, Aspirin pharmacology, Cattle, Dinoprostone, Dose-Response Relationship, Drug, Endothelium drug effects, Fatty Acids analysis, Female, Ibuprofen pharmacology, Indomethacin pharmacology, Kinetics, Male, Phospholipids analysis, Prostaglandins E pharmacology, Pulmonary Artery cytology, SRS-A pharmacology, Time Factors, Arachidonic Acids pharmacology, Endothelium cytology
- Abstract
The addition of arachidonic acid (20:4), but not other fatty acids, including the structurally similar eicosapentaenoic acid (20:5), induced specific morphological changes in cultured endothelial cells derived from bovine aorta and pulmonary artery. Cells exhibited a time- and dose-dependent change from their normal, epithelioid morphology to become elongated, polygonal, and spindle-shaped. Cells isolated from aorta appeared more sensitive to these changes than those from pulmonary artery. The effect was observed as early as 12 h after exposure to 20:4, required 48 h for maximal expression, and could be reversed in 2-5 h after change to normal media. The morphological alteration was not observed in cells treated with leukotrienes or PGE2. When cells were pretreated with ibuprofen, aspirin, or indomethacin to block prostaglandin synthesis and then exposed to 20:4, the dose-response effect was shifted to the left. This increased sensitivity to 20:4 suggests either a direct effect of 20:4 on cell morphology or an indirect effect due to metabolites of 20:4 which are not dependent on the cyclooxygenase pathway.
- Published
- 1985
- Full Text
- View/download PDF
47. Primary empty sella, galactorrhea, hyperprolactinemia and renal tubular acidosis.
- Author
-
Bar RS, Mazzaferri EL, and Malarkey WB
- Subjects
- Adult, Diagnosis, Differential, Female, Growth Hormone metabolism, Humans, Pituitary Neoplasms diagnostic imaging, Pneumoencephalography, Pregnancy, Prolactin metabolism, Acidosis, Renal Tubular complications, Galactorrhea complications, Lactation Disorders complications, Prolactin blood, Sella Turcica diagnostic imaging
- Abstract
Discussed here is a 41 year old woman with galactorrhea associated with the empty sella syndrome and mild renal tubular acidosis. Basal serum prolactin (PRL) levels were normal, but a 24 hour serum PRL secretory profile demonstrated an increased mean PRL concentration. Serum PRL was appropriately suppressed by the administration of L-dopa; however, chlorpromazine stimulation resulted in a blunted serum PRL response. Pituitary luteinizing hormone, follicle stimulating hormone, ACTH and thyroid stimulating hormone levels were normal. Thus, galactorrhea associated with an enlarged sella does not establish the diagnosis of a pituitary tumor, and pneumoencephalography must be performed to exclude the empty sella syndrome.
- Published
- 1975
- Full Text
- View/download PDF
48. Distinct receptors for IGF-I, IGF-II, and insulin are present on bovine capillary endothelial cells and large vessel endothelial cells.
- Author
-
Bar RS and Boes M
- Subjects
- Animals, Antibodies, Antigen-Antibody Complex, Cattle, Cells, Cultured, Endothelium metabolism, Insulin metabolism, Kinetics, Peptides metabolism, Receptors, Somatomedin, Somatomedins metabolism, Aorta metabolism, Capillaries metabolism, Pulmonary Artery metabolism, Receptor, Insulin metabolism, Receptors, Cell Surface metabolism
- Abstract
Endothelial cells were cultured from bovine fat capillaries, aortae and pulmonary arteries and their interactions with 125I-IGF-I, 125I-MSA (an IGF-II), 125I-insulin and the corresponding unlabeled hormones were evaluated. Each endothelial culture showed similar binding parameters. With 125I-insulin, unlabeled insulin competed with high affinity while IGF-I and MSA were approximately 1% as potent. With 125I-MSA, MSA was greater than or equal to IGF-I in potency and insulin did not compete for binding. Using 125I-IGF-I, IGF-I was greater than or equal to MSA whereas insulin decreased 125I-IGF-I binding by up to 72%. Exposing cells to anti-insulin receptor antibodies inhibited 125I-insulin binding by greater than 90%, did not change 125I-MSA binding, while 125I-IGF-I binding was decreased by 30-44%, suggesting overlapping antigenic determinants between IGF-I and insulin receptors that were not present on MSA receptors. We conclude that cultured capillary and large vessel endothelial cells have distinct receptors for insulin, IGF-I and MSA (IGF-II).
- Published
- 1984
- Full Text
- View/download PDF
49. Extreme insulin resistance in ataxia telangiectasia: defect in affinity of insulin receptors.
- Author
-
Bar RS, Levis WR, Rechler MM, Harrison LC, Siebert C, Podskalny J, Roth J, and Muggeo M
- Subjects
- Acanthosis Nigricans complications, Adolescent, Adult, Ataxia Telangiectasia complications, Ataxia Telangiectasia genetics, Blood Glucose metabolism, Female, Fibroblasts metabolism, Glucose Tolerance Test, Humans, Insulin blood, Insulin metabolism, Male, Middle Aged, Monocytes metabolism, Ataxia Telangiectasia metabolism, Insulin Resistance, Receptor, Insulin metabolism
- Abstract
The syndrome of ataxia telangiectasia is associated with glucose intolerance and insulin resistance. We examined the status of insulin receptors on circulating monocytes and on cultured fibroblasts from two siblings with ataxia telangiectasia and severe insulin resistance. 125I-insulin binding to monocytes of the two patients consistently demonstrated an 80 to 85 per cent decrease in receptor affinity. In contrast, the defect in receptor affinity was not expressed on the patients' cultured fibroblasts or on monocytes or fibroblasts obtained from unaffected family members. Whole plasma and immunoglobulin-enriched fractions of plasma from the patients inhibited the normal binding of insulin to its receptors on cultured human lymphocytes (IM -9 line) and on human placental membranes. We conclude that the insulin resistance in the two siblings with ataxia telangiectasia was associated with defects in the affinity of the receptors for insulin, probably caused by circulating inhibitors of insulin binding.
- Published
- 1978
- Full Text
- View/download PDF
50. Insulin receptors in human endothelial cells: identification and characterization.
- Author
-
Bar RS, Hoak JC, and Peacock ML
- Subjects
- Binding, Competitive, Endothelium metabolism, Female, Humans, Insulin analogs & derivatives, Insulin metabolism, Kinetics, Pregnancy, Receptor, Insulin isolation & purification, Receptor, Insulin metabolism, Umbilical Veins metabolism
- Abstract
Specific binding of 125I-insulin was found in cultured human endothelial cells obtained from human umbilical veins. The binding reaction was rapid and reversible, demonstrated receptor site-site interactions of the negatively cooperative type, and was dependent on the temperature, pH and duration of incubation. At 21 degrees C, steady-state conditions of binding occurred in 90 minutes, the pH optimum was 7.8 and less than 10% of the labeled hormone was degraded. Binding of tracer amounts of 125I-insulin was inhibited by concentrations of unlabeled insulin as low as 0.2 ng/ml and 50% inhibition was obtained at 2-5 ng/ml of unlabeled insulin. Unlabeled porcine insulin, porcine proinsulin and desoctapeptide insulin inhibited the binding of 125I-porcine insulin in direct proportion to their biological potencies, whereas to the cells was inhibited by antibodies against insulin receptors. We conclude that human endothelial cells possess specific receptors for insulin whose physio-chemical properties are similar to those of insulin receptors in other tissues.
- Published
- 1978
- Full Text
- View/download PDF
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