Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Structural alteration of insulin-like growth factor binding protein-3 (IGFBP-3) resulting from limited proteolysis by one or more serine proteases in vivo was first described in the serum of pregnant women and in certain pathological conditions. Western immunoblotting has since been employed to detect the phenomenon in normal serum, using a polyclonal antibody raised against recombinant human IGFBP-3 and a highly sensitive technique of visualization by chemiluminescence. The major proteolytic fragment of 30 kDa, which fails to be detected in native serum by ligand blotting owing to its weak affinity for IGFs, has proved clearly visible in all serum samples tested, sometimes accompanied by smaller fragments of 20 and 16 kDa. Among the serum samples analysed, increasing proportions of proteolysed IGFBP-3 were found in the following order: acromegalic patients, normal subjects, GH-deficient patients, pregnant women. In RIAs done with the same antibody, many of the serum samples yielded dose-response curves which were not parallel with standard curves, with lower gradients. In the samples where measurements were possible, apparent IGFBP-3 levels proved lower in pregnant women (2.28 +/- 0.23 mg/l, mean +/- SEM) than in normal adults (4.26 +/- 0.33 mg/l, P < 0.001). These observations, which contradict earlier reports of higher levels in pregnant women, suggest that the 30 kDa proteolytic fragment has a weaker affinity for the antibody than the intact IGFBP-3 (which in ligand- and immunoblotting appears as a characteristic 42-39 kDa doublet and which is barely or not detectable in pregnancy serum).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Protease-induced alteration of insulin-like growth factor binding protein-3 as detected by radioimmunoassay. Agreement with ligand blotting data. 752 85

Centers have reported superior growth in children on peritoneal dialysis (PD) as compared to hemodialysis (HD). Many factors may influence this outcome including diet, adequacy of dialysis, and control of metabolic acidosis. The role of insulin-like growth factor-1 (IGF-1) and its bioactivity in patients with end-stage renal disease (ESRD) have been recently examined. Insulin-like growth factor binding protein-3 (IGFBP-3) has been shown to be elevated in ESRD, possibly resulting in inhibition of the bioactivity of IGF-1. Potentially, the removal of IGFBP-3 may improve the bioactivity of IGF-1, with resulting improvement in growth. The molecular weight of IGFBP-3 (30.5 kDa) is in the range of other proteins cleared by PD (e.g., albumin-69 kDa). Therefore, we have analyzed 10 samples of IGFBP-3 in the dialysis effluent of 9 children on peritoneal dialysis, and have found that the mean level +/- SEM was 0.21 +/- 0.03 mg/L, while the 3 analyses of children on standard HD was 0.02 +/- 0.01 mg/L. In addition, the effluent of 2 children on a high-efficiency dialyzer had an IGFBP-3 level of 0.45 +/- 0.25 mg/L. Even though quite preliminary, these data may suggest another reason for improved growth in children on PD and a potential advantage to high-efficiency HD. Further analysis in a larger population of ESRD patients will be needed in order to confirm these preliminary findings.
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PMID:Dialysis modality comparison of insulin-like growth factor binding protein-3 removal in children: could this have a potential growth benefit? 752 57

Epidermal growth factor receptor (EGFR) ligands are fundamental regulators of epithelial growth, differentiation, and neoplastic transformation. In addition to being potent mitogens for murine epidermal keratinocytes in vitro, transforming growth factor alpha (TGF alpha) and EGF elicit distinctive changes in keratin expression: Ca(2+)-mediated induction of the differentiation-specific keratins K1 and K10 is blocked, while simple epithelial keratins K8 and K18 are expressed aberrantly (C. Cheng et al., Cell Growth, & Differ., 4: 317-327, 1993). We have evaluated several additional growth factors to determine the specificity of this response for EGFR ligands. TGF alpha, keratinocyte growth factor (KGF), and acidic fibroblast growth factor (aFGF), but not basic fibroblast growth factor (bFGF) or insulin-like growth factor type I, block Ca(2+)-mediated expression of K1 while inducing K8. Since KGF and aFGF (but not bFGF) are ligands for the KGF receptor (KGFR), we explored the possibility that the TGF alpha/EGFR pathway is an intermediary in signaling through the KGFR. TGF alpha mRNA was increased in cells treated with KGF, aFGF, or TGF alpha but not bFGF or insulin-like growth factor type I. Similar changes were detected at the protein level; TGF alpha in conditioned medium (CM) from control, KGF-, TGF alpha-, and aFGF-treated cultures was 54 (+/- 8, SEM), 365 (+/- 50), 146 (+/- 20), and 120 (+/- 50) pg/ml, respectively. KGF and TGF alpha also increased expression of cell-associated TGF alpha measured in keratinocyte lysates. KGF increased TGF alpha secretion and mRNA levels in human as well as mouse keratinocytes. CM from KGF-treated cultures stimulated cell growth when added to cultures of normal keratinocytes. Preincubation with neutralizing antibodies to both TGF alpha and KGF, but not KGF antibody alone, blocked cell growth in cultures treated with KGF CM, suggesting that the predominant keratinocyte mitogen in KGF CM is TGF alpha. In support of this hypothesis, treatment of keratinocytes for 5 min with either KGF CM or purified TGF alpha resulted in EGFR autophosphorylation. Furthermore, after approximately 24 h, KGF as well as TGF alpha induced EGFR down-regulation based on Western blot analysis and 125I-EGF binding. Induction of TGF alpha in KGF-treated keratinocytes, coupled to activation and down-modulation of the EGFR, suggests that TGF alpha may be a proximal effector of KGF action for at least certain aspects of epidermal growth and differentiation.
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PMID:Keratinocyte growth factor receptor ligands induce transforming growth factor alpha expression and activate the epidermal growth factor receptor signaling pathway in cultured epidermal keratinocytes. 753 82

The liver is thought to be the major source of circulating insulin-like growth factor (IGF-I) and IGF-binding protein-1 (IGFBP-1), whereas the primary production site of circulating IGFBP-3 remains unknown. As other tissues may contribute to the circulating pool of IGF-I and IGFBP, the aim of the present study was to assess the hepatic and renal arterio-venous difference and production rates of IGF-I, IGFBP-1, IGFBP-3, and GH in cirrhotic patients (n = 22) and matched control subjects (n = 27). IGFBP-1 and -3, IGF-I, and GH levels were measured by RIA in hepatic, renal, and peripheral veins and in the femoral artery. Levels of IGFBP-1 to -4 were additionally determined by Western ligand blotting. Hepatic venous IGFBP-1 was significantly increased in the cirrhotic patients (mean +/- SEM, 33.6 +/- 9.1 vs. 10.4 +/- 1.9 micrograms/L; P < 0.001), and arterio-renal-venous extraction was significant in both patients (6 +/- 2%; P < 0.01) and controls (11 +/- 1%; P < 0.001). Conversely, IGFBP-3 was decreased in the cirrhotic patients (1265 +/- 149 vs. 2712 +/- 137 micrograms/L; P < 0.001). IGFBP-3 correlated significantly with the wedged hepatic venous pressure (r = -0.49; P < 0.05), serum aspartate aminotransferase (r = -0.66; P < 0.01), serum bilirubin (r = -0.65; P < 0.01), serum albumin (r = 0.64; P < 0.01), and the Child score (r = -0.57; P < 0.01). IGF-I was significantly lower in the cirrhotics (57 +/- 10 vs. 143 +/- 11 micrograms/L; P < 0.001). No significant IGFBP-3 proteolysis was demonstrated in cirrhotics or controls. No significant differences were found in the values obtained simultaneously from hepatic, renal, and brachial veins or femoral artery, which suggests that no major net production or release of IGFBP-3 or IGF-I occurs in these tissues. No differences in IGFBP-2 or IGFBP-4 determined by Western ligan blot were found between patients and controls. The IGF-I concentrations correlated significantly with parameters of biochemical liver function. Basal GH concentrations were significantly higher in the cirrhotics (1.19 +/- 0.13 vs. 0.58 +/- 0.08 micrograms/L; P < 0.001). A significant hepatic disposal of GH was found in the patients (P < 0.05) and controls (P < 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Concentrations, release, and disposal of insulin-like growth factor (IGF)-binding proteins (IGFBP), IGF-I, and growth hormone in different vascular beds in patients with cirrhosis. 753

The failure of chronic wounds to heal remains a major medical problem. Recent studies have suggested an important role for growth factors in promoting wound healing. We investigated the mitogenic effect of basic fibroblast growth factor (FGF), insulin-like growth factor-1 (IGF-1), and epidermal growth factor (EGF), comparing their effects with those of media alone (MEM) in a human skin explant model. A stable organ culture system for maintaining the histologic structure of human epidermis for 10 days in vitro was developed. DNA synthesis was measured on Days 1, 3, and 7 of organ culture using [3H]thymidine ([3H]thy) uptake and expressed as cpm/mg dry weight (mean +/- SEM). FGF, IGF-1, and EGF were each capable of stimulating [3H]thy uptake on Day 1 of culture (2372 +/- 335 FGF, 2226 +/- 193 IGF-1, 4037 +/- 679 EGF vs 1108 +/- 70 MEM, P < 0.05). IGF-1 and EGF also stimulated [3H]thy uptake on Days 3 and 7 of culture. The organ culture system was further employed to observe epidermal outgrowth. Longest keratinocyte outgrowth from the explant periphery (simulating epithelial regeneration from the wound edge) was observed on Day 7. EGF resulted in maximum stimulation of epithelial outgrowth (440 +/- 80 microns), followed by FGF (330 +/- 56 microns), IGF-1 (294 +/- 48 microns), and MEM (189 +/- 50 microns). We postulate, therefore, that FGF, IGF-1, and EGF are important mitogens for wound healing and that EGF in particular is capable of stimulating epithelialization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of growth factors on cell proliferation and epithelialization in human skin. 754 31

This study examines acute changes in circulating levels of atrial natriuretic peptide (ANP) and insulin-like growth factor (IGF-1) during short periods of myocardial ischemia experienced at coronary angioplasty. Ten patients (mean age 55.7 +/- 3.9 years, nine men) undergoing angioplasty to the left anterior descending coronary artery were studied. Angioplasty of the left anterior descending coronary artery was performed with the balloon inflations maintained at 6 to 10 atm for 20 to 90 seconds. Blood was sampled from the coronary sinus for ANP, IGF-1 (both total and free), and lactate levels at (1) after catheterization of the coronary sinus, (2) after the initial left coronary angiography, (3) immediately after balloon deflation, and (4) 5 minutes after deflation. ANP levels (pmol/L +/- SEM) rose significantly at the end of balloon deflation (13.4 +/- 2.8; p < 0.01) compared with baseline levels (8.8 +/- 1.9). This rise was sustained for at least 5 minutes after balloon deflation (13.7 +/- 3.1; p < 0.01). ANP levels were not affected by the injections of angiographic contrast media. Free IGF-1 levels rose after injections of radiographic contrast but not after balloon inflation or deflation. Total IGF-1 levels did not change significantly at any of the sampling times. Lactic acid (mmol/L) levels rose at the end of balloon inflation (2.66 +/- 0.6) compared with baseline (2.13 +/- 0.7; p < 0.05) but returned to normal within 5 minutes of balloon deflation. Neither lactic acid levels nor release of ANP or IGF-1 correlated with the initial left ventricular end-diastolic pressure or the degree of electrocardiographic ST depression during the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Acute changes in atrial natriuretic peptide, insulin-like growth factor-1, and lactate levels during left anterior descending coronary artery angioplasty. 757 78

To study the possible role of insulin-like growth factor binding proteins (IGFBPs) in the discrepancy between normal or only slightly retarded growth and substantially reduced concentrations of insulin-like growth factor I (IGF-I) in prepubertal children with insulin-dependent diabetes mellitus (IDDM), we measured the plasma concentrations of IGF-I, IGFBP-1, IGFBP-2 and IGFBP-3 and free insulin in 24 prepubertal diabetic subjects and 12 control children. In addition, the growth hormone response to exercise was evaluated. The diabetic children had significantly decreased peripheral IGF-I levels (8.2 + 1.1 (SEM) vs 16.7 + 2.5 nmol/l; p < 0.001), whereas the concentrations of free insulin were increased (217 + 14 vs 103 + 21 pmol/l; p < 0.001). The concentrations of IGFBP-1 and IGFBP-3 were of the same magnitude in both groups. The diabetic children had significantly increased levels of IGFBP-2 (465 + 13 vs 416 + 14 micrograms/l; p = 0.029), which were inversely related to the circulating IGF-I levels (r = -0.35; p = 0.034). The diabetic and control children had comparable growth hormone responses to exercise. Diabetic children with poor glucose control had even lower IGF-I levels than those with moderate metabolic control (6.0 + 0.8 vs 10.3 + 1.7 nmol/l; p = 0.037). No differences could be observed in the plasma concentrations of various IGFBPs between these two groups of diabetic subjects. The absence in prepubertal diabetic children of increased IGFBP-1 levels observed in adolescent and adult patients with IDDM may contribute to their maintained linear growth, despite definitely decreased IGF-I concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Insulin-like growth factor binding proteins in prepubertal children with insulin-dependent diabetes mellitus. 758 67

The increase in GH production during the male adolescent growth spurt has been attributed to both androgen and estrogen receptor-mediated processes. To evaluate the role of endogenous estrogens in the control of GH secretion, we administered the estrogen receptor antagonist tamoxifen to 10 late pubertal males. Blood samples were obtained for GH determination at 10-min intervals on 2 occasions during the last 24 h of a 4-day course of either tamoxifen or placebo. Waveform-specific, multiple parameter deconvolution analysis was employed to assess GH secretory and elimination dynamics. Estrogen receptor blockade resulted in a significant (P < 0.05) diminution in mean 24-h serum GH concentrations, from 3.9 +/- 1.0 (placebo; mean +/- SEM) to 2.7 +/- 0.6 micrograms/L (tamoxifen). This was associated with a significant (P < 0.01) decline in the GH production rate [237 +/- 55 vs. 155 +/- 33 micrograms/L GH distribution volume (Lv).24 h]. Furthermore, this reduction in GH secretion was the result of significant decreases in both the maximal GH secretory rate (0.46 +/- 0.08 vs. 0.34 +/- 0.06 microgram/Lv.min; P < 0.01) and, to a smaller degree, GH secretory burst number (16 +/- 1 vs. 14 +/- 1/24 h; P < 0.05). There was also a trend toward reduced mass of GH secreted per burst (13.3 +/- 2.5 vs. 10.3 +/- 2.0 micrograms/Lv; P = 0.06). No significant alterations in either GH elimination t1/2 or GH secretory burst half-duration were observed during estrogen receptor antagonism. Tamoxifen treatment was associated with a significant (P < 0.05) decrease in plasma insulin-like growth factor-I concentrations. However, total and free testosterone, 17 beta-estradiol, insulin-like growth factor-binding protein-3, and pooled 24-h LH concentrations were not significantly changed by short term blockade of estrogen action. We postulate that endogenous estrogens play a facilitatory role in neuroendocrine control of the somatotropic axis during puberty in boys. Tamoxifen blocks this estrogen-dependent stimulation of GH secretion without altering the hormone elimination t1/2. Furthermore, we speculate that any stimulatory role of androgens on GH secretion is exerted primarily through the estrogen receptor after aromatization.
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PMID:Estrogen receptor blockade with tamoxifen diminishes growth hormone secretion in boys: evidence for a stimulatory role of endogenous estrogens during male adolescence. 804 71

Recent studies have shown that the basal release of PRL from anterior pituitary cells is inhibited by endothelin-1 (ET-1) and ET-3. To determine whether ET also regulates the synthesis and release of PRL by decidual cells, we examined the effects of ET on the synthesis and release of PRL from an enriched fraction of human decidual cells prepared by isopycnic centrifugation of enzymatically dispersed term decidual tissue. Exposure of decidual cells to ET-1 (10(-7) M) for 96 h caused a progressive decrease in basal PRL synthesis and release beginning 24 h after exposure with half-maximal inhibition occurring at an ET-1 concentration of 5 x 10(-9) M. Between 72-96 h of culture, ET-1-exposed cells synthesized 37.2 +/- 2.7% (SEM) and released 32.3 +/- 1.3% less PRL than control cells (P < 0.01). ET-1-exposed cells incubated with [35S]methionine between 72-96 h also released less [35S] PRL than control cells. Sarafotoxin S6C, an ETB receptor agonist, also inhibited basal PRL release, whereas BQ-123, an ETA receptor antagonist, had no effect on basal or on ET-1-mediated inhibition of PRL release. ET-1 also markedly inhibited the stimulation of PRL synthesis and release in response to insulin and insulin-like growth factor-1 (IGF-1). Cells exposed to insulin (100 ng/ml) and IGF-1 (50 ng/ml) alone released 61.2 +/- 3.6% and 40.0 +/- 3.8% more PRL, respectively, than control cells between 72-96 h of exposure. However, cells exposed simultaneously to insulin and ET-1 (10(-7) M) released only 17.1 +/- 3.5% more PRL than control cells during the same time period, and cells exposed simultaneously to IGF-1 and ET-1 released only 4.1 +/- 1.8% more PRL than controls during the same time interval (P vs. insulin or IGF-1 alone < 0.001 in each instance). Both basal and insulin- and IGF-1-stimulated PRL release were also inhibited by the ET isotypes ET-2 and ET-3, and by the ET-1 precursor, big ET. Since macrophages and decidual cells synthesize ET, and decidual tissue contains specific receptors for ET, the inhibitory action of ET on basal and stimulated PRL release may result from an autocrine and/or paracrine effect and appears to be mediated through the ETB receptor.
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PMID:Endothelin inhibits basal and stimulated release of prolactin by human decidual cells. 834 96

Malnutrition in hemodialysis patients is associated with increased morbidity and mortality. The use of intradialytic parenteral nutrition (IDPN) to improve nutritional parameters has been shown to be of limited benefit in most studies. We studied the use of recombinant human growth hormone (rHuGH) in potentiating the effects of IDPN in seven hemodialysis patients dialyzed with a Kt/V of 1.03 +/- 0.11 (mean +/- SEM), but with evidence of malnutrition: albumin, 3.2 +/- 0.18 g/dL; transferrin, 215 +/- 30 mg/dL; insulin-like growth factor-1 (IGF-1), 115 +/- 19 ng/mL, protein catabolic rate (PCR), 0.70 +/- 0.05 g/kg/d; and weight, 12.3% +/- 4.0% below ideal body weight. During 6 weeks of IDPN, resulting in an additional 18 +/- 4 kcal and 0.69 +/- 0.03 g of protein/kg body weight per dialysis session, albumin concentration increased to 3.5 +/- 0.14 g/dL (compared with baseline, P = NS), transferrin increased to 279 +/- 36 mg/dL (P < 0.002), IGF-1 increased to 152 +/- 32 ng/mL (P = NS), and PCR increased to 0.81 +/- 0.04 g/kg/d (P = NS). During the next 6 weeks, IDPN administration was continued and rHuGH, at a dose of 5 mg subcutaneously during each dialysis, was added to the regimen. This resulted in an increase in albumin concentration to 3.8 +/- 0.08 g/dL (P < or = 0.04 compared with end of IDPN phase), an increase in transferrin to 298 +/- 41 mg/dL (P = NS compared with end of IDPN phase), and an increase in IGF-1 to 212 +/- 45 ng/mL (P = 0.05 compared with end of IDPN phase).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effects of recombinant human growth hormone and intradialytic parenteral nutrition in malnourished hemodialysis patients. 848 21


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