Development and Validation of a Specific Radioimmunoassay for Somatostatin in Human Plasma

Penman, Erica; Wass, John; Lund, Alison; Lowry, P. J.; Stewart, Jesse C.; Dawson, A. M.; Besser, G. M.; Rees, Lesley

doi:10.1177/000456327901600103

Cited by 113 publications

(34 citation statements)

References 44 publications

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“…IRS was measured in triplicate, (20). This was observed by others with an antiserum directed towards the central portion of soIllatostatinl (22). [1251-Tvri l] somatostatin also gave a greater sensitivity (detection limit 10.0 pg/tube or 100 pg/ml perfusate versus 14.3 pg/tube previously reported [21]).…”

Section: Analysesmentioning

confidence: 60%

Clearance of Immunoreactive Somatostatin by Perfused Rat Liver

Sacks¹,

Terry²

1981

J. Clin. Invest.

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Section: Analysesmentioning

confidence: 60%

Clearance of Immunoreactive Somatostatin by Perfused Rat Liver

Sacks¹,

Terry²

1981

J. Clin. Invest.

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“…Tyr'4-S-28 [1][2][3][4][5][6][7][8][9][10][11][12][13][14], Tyr'-S-14, and Tyr"-S-14 were purchased from Peninsula Laboratories, San Carlos, CA. S-14, S-13, S-12, and analogues of S-14 in which alanine or tyrosine was substituted for residues at the 5, 6, 8, and 10 positions were gifts from Dr. J. Rivier, Salk Institute, La Jolla, CA.…”

Section: Methodsmentioning

confidence: 99%

“…Because S-14 is secreted from cells that are widely distributed, notably in the central and peripheral nervous systems, pancreas, and GI tract (3)(4)(5)(6), the prevailing belief is that it acts on adjacent cells to modulate the release of specific secretory products (7,8). On the other hand, somatostatin-like immunoreactivity (SLI) is present in mammalian plasma (9)(10)(11)(12)(13), and rises after ingestion of nutrients or infusion of supraphysiologic doses of neurotransmitters and selected GI peptides (14)(15)(16)(17)(18)(19). From immune neutralization studies in dogs and S- 14 infusions into man mimicking postprandial levels of SLI, Schusdziarra et al (20) and Zyznar and colleagues (21), postulated that circulating S-14 acts as a hormone that may be involved in nutrient assimilation.…”

Section: Introductionmentioning

confidence: 99%

Circulating prosomatostatin-derived peptides. Differential responses to food ingestion.

et al. 1989

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Prosomatostatin (pro-S) and its bioactive posttranslational products, somatostatin-14 (S-14), somatostatin-13 (S-13), and somatostatin-28 (S-28), were measured in human plasma by the use of immunoglobulins to the NH2-terminus of S-28 conjugated with agarose to separate them and, thereafter, by RIA with an antiserum recognizing the COOH-terminus of pro-S, and by specific RIA for the NH2-terminus of S-14 and pro-S. In healthy men, mean basal levels of pro-S were 4 pg equivalent S-14/ml; S-14/S-13 combined were 9 pg equivalent S-14/ ml; and S-28 levels were 16 pg/ml. After a 700-kcal meal, pro-S, S-14, and S-14/S-13 did not change, whereas S-28 levels doubled by 120 min and remained elevated for 240 min. To evaluate the origins of these peptides, their levels were compared in peripheral, portal, gastric, and mesenteric veins of anesthetized patients and in patients with total resection of stomach and pancreas before and after nutrient intake. The stomach and small intestine were sources of both peptides; however, most S-28 originated in the small intestine. These findings suggest that, in contrast to S-14, S-28 is a hormone and may modulate postprandial nutrient absorption and use.

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“…SLI was measured by radioimmunoassay (Euro-Diagnostica, Malmö , Sweden). Before assay, somatostatin was extracted using Vycor, a leached silica glass, as previously described (26). The extraction recovery was similar for plasma and vitreous samples (75-85%).…”

Section: Vitrectomy and Sample Collectionmentioning

confidence: 99%

“…All samples were diluted in parallel to the cyclic somatostatin standard. Validation of the assay has previously been reported in detail (26). Protein assay.…”

mentioning

confidence: 99%

Deficit of Somatostatin-Like Immunoreactivity in the Vitreous Fluid of Diabetic Patients

et al. 2002

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OBJECTIVE -To evaluate the vitreous levels of somatostatin-like immunoreactivity (SLI) in patients with proliferative diabetic retinopathy (PDR). RESEARCH DESIGN AND METHODS-A total of 14 diabetic patients with PDR, in whom a vitrectomy was performed, were included in the study. Sixteen nondiabetic patients, with other conditions requiring vitrectomy, served as a control group. Both venous blood and vitreous samples were collected at the time of vitreoretinal surgery. Patients in whom intravitreous hemoglobin was detectable were excluded. In addition, a correction for plasma levels of SLI and intravitreal proteins was performed. SLI was measured by radioimmunoassay and vitreous hemoglobin by spectrophotometry.RESULTS -SLI in the vitreous fluid was significantly lower in diabetic patients than in the control group (68 Ϯ 18.7 vs. 193.6 Ϯ 30.8 pg/ml, P Ͻ 0.01). The vitreous SLI-to-plasma SLI ratio was strikingly higher in nondiabetic subjects than in diabetic patients with PDR (5.3 [1.2-71.1] vs. 0.6 [0.03-4.1], P Ͻ 0.01). After correcting for total vitreous protein concentration, SLI (pg/mg of proteins) remained significantly higher in nondiabetic control subjects than in diabetic patients with , P Ͻ 0.0001). Remarkably, intravitreous levels of SLI were higher than those obtained in plasma in nondiabetic control subjects (193.6 Ϯ 30.8 vs. 43.5 Ϯ 10.7 pg/ml, P Ͻ 0.0001). Finally, a lack of relationship between plasma and vitreous levels of SLI was observed in both diabetic patients with PDR and nondiabetic control subjects.CONCLUSIONS -The significantly higher SLI in the vitreous fluid than in plasma detected in nondiabetic control subjects supports the concept that somatostatin plays a relevant role in retinal homeostasis. In addition, the intravitreous deficit of SLI observed in diabetic patients with PDR suggests that it might contribute to the process of retinal neovascularization. Diabetes Care 25:2282-2286, 2002S omatostatin is a peptide that was originally identified as the hypothalamic factor responsible for inhibition of the release of growth hormone (GH) from the anterior pituitary (1). Subsequent studies have shown that somatostatin has a much broader spectrum of inhibitory actions and that it is much more widely distributed in the body, occurring not only in many regions of the central nervous system but also in many tissues of the digestive tract, including the stomach, intestine, and pancreas (2). Somatostatin-14 and -28 are the two principal bioactive products cleaved from the COOH-terminus of prosomatostatin in different cells and the main circulating forms of somatostatin (2,3). Somatostatin-13, converted from somatostatin-14 by the action of tissue aminopeptidases, is also present in plasma as prosomatostatin, and collectively all of these peptides contribute to the measurement of somatostatin-like immunoreactivity (SLI) (3). Somatostatin mediates its multiple biologic effects via specific plasma membrane receptors that belong to the family of G-protein-coupled receptors having seven transmembrane...

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Development and Validation of a Specific Radioimmunoassay for Somatostatin in Human Plasma

Cited by 113 publications

References 44 publications

Clearance of Immunoreactive Somatostatin by Perfused Rat Liver

Clearance of Immunoreactive Somatostatin by Perfused Rat Liver

Circulating prosomatostatin-derived peptides. Differential responses to food ingestion.

Deficit of Somatostatin-Like Immunoreactivity in the Vitreous Fluid of Diabetic Patients

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