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)

Synthetic porcine secretion was labelled by the conjugation-labelling method of Bolton & Hunter, the lactoperoxidase method, the gaseous diffusion method, and the chloramine-T method. The chloramine-T technique was adapted as routine method. Ten mug (3.27 nmol) peptide was reacted with 5 mCi of Na125I at a concentration of chloramine-T of 1.3 mmol/l. Synthetic secretin was suitable for labelling for at least eight months when stored as dry matter in nitrogen-filled glass ampoules. Purification and separation of labelled from unlabelled hormone was carried out by gel-permeation chromatography on Sephadex G-50 superfine. The labelled preparation had a specific radioactivity of 405 +/- 33 muCi/nmol (mean +/- SEM., n = 9) and was unable for six days. 6-tyrosyl-secretin took more iodine compared to porcine synthetic secretin but had lower immunoreactivity with all antisera tested.
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PMID:Preparation of 125I-labeled synthetic porcine secretin for radioimmunoassay. 1 92

The effectiveness of an antibody-enzyme immunotoxin (eIT) was investigated on human T cells. This enzyme immunotoxin contained glucose oxidase (GO) and lactoperoxidase (LPO) chemically coupled to the pan-leukocyte-specific mouse monoclonal antibody (MoAb) 097 (097-GO and 097-LPO). Human peripheral blood mononuclear cells or tumor cells were suspended in a mixture of 097-GO and 097-LPO for 30 min, and then for 2 h with glucose and NaI. The effectiveness of this eIT system was indicated by the almost complete reduction of T cell viability, as estimated by a phytohemagglutinin induced proliferation assay (99.4% +/- 0.31 depletion, mean +/- SEM of 15 experiments). The specificity of the cytotoxicity reaction was indicated by the lack of cytotoxicity of control irrelevant MoAb conjugates to T cells (1.9% +/- 4.17 of T cell depletion, eight experiments). The growth of human bone marrow myeloid progenitors (CFU-GM) was not affected by the conjugates even by increasing 100-fold the optimal cytotoxic dose. T cells were susceptible to the conjugates in the presence of up to 90% of erythrocytes. This eIT system may thus represent a new alternative immunospecific procedure for allograft and/or autograft purging, and appears to effectively replace complement-mediated methods of T cell depletion.
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PMID:An immunotoxin system intended for bone marrow purging composed of glucose oxidase and lactoperoxidase coupled to monoclonal antibody 097. 279 Mar 30

The receptor binding characteristics and biological activity of single site monoiodinated insulin was investigated using isolated rat adipocytes. Pork insulin was iodinated by the lactoperoxidase method, and each of the four monoiodo derivatives (iodotyr-A14, iodotyr-A19, iodotyr-B16, and iodotyr-B26) was isolated by high performance liquid chromatography. Both radioactive 125I-labeled and nonradioactive 127I-labeled iodoinsulins were prepared. In competitive binding experiments in which each 125I-labeled iodoisomer competed for receptor binding at 15 C with its homologous 127I-labeled iodoisomer, the concentrations of homolog required for 50% inhibition of tracer binding were 1.67 +/- 0.06, 2.14 +/- 0.23, and 2.35 +/- 0.27 X 10(-9) M for the B26, A14, and B16 iodoisomers, respectively (mean +/- SEM; n = 3). Scatchard analysis of the homologous competition curves using a two-site model indicated that there was no difference in the total number of specific sites to which each isomer could bind or in their affinity for binding to the low affinity site. However, a significantly (P less than 0.05) higher affinity for (B26)iodoinsulin binding to the high affinity site was observed compared to either the (A14)- or (B16)iodoisomers (Kd values of 1.09 +/- 0.18, 2.09 +/- 0.40, and 2.24 +/- 0.15 X 10(-9) M for B26, A14, and B16, respectively). Degradation of the isomers by adipocytes incubated at 37 C occurred at a rate proportional to their receptor binding affinity. The biological activity of iodoinsulins was also evaluated, based on the ability either to stimulate glucose oxidation or to exert an antilipolytic effect. The 127I-labeled (B26)iodoisomer exhibited the greatest potency in both assays compared to either (A14)- or (B16)iodoinsulins, consistent with its higher apparent affinity for receptor binding. The receptor-binding activity and biological potency of unmodified native insulin and 127I-labeled (A14)-iodoinsulin were directly compared. Identical results were obtained for each in both types of assay, suggesting that (A14)iodoinsulin is a valid tracer for insulin with isolated adipocytes. We conclude that in isolated rat adipocytes, (B26)iodoinsulin has greater activity than either unlabeled insulin or the other iodinated derivatives. (A14)Iodoinsulin is indistinguishable from native insulin; (B16)iodoinsulin has slightly reduced activity, while that of (A19)iodoinsulin is considerably reduced.
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PMID:Receptor binding and biological activity of specifically labeled [125I]- and [127I]monoiodoinsulin isomers in isolated rat adipocytes. 637 Jun 67

A sensitive radioimmunoassay (RIA) for canine growth hormone (GH) was developed. Antibodies were elicited in rhesus monkeys. One antiserum exhibited a working titer at a dilution of 1: 500 000. Radioiodination was performed enzymatically employing lactoperoxidase. Logit-log transformation and least squares fitting resulted in straight line fitting of the standard curve between 0.39 and 50 ng/ml. Formation of large-molecular [125I]GH during storage caused diminished assay sensitivity. Therefore [125I]GH was re-purified by gel chromatography. Using this procedure, high and reproducible assay sensitivity was obtained. Tracer preparations were used for as long as 3 months after iodination. Diluted plasma from normal and acromegalic dogs resulted in a dose-response curve parallel to the standard curve. Canine prolactin exhibited a cross-reactivity of 2%. The within-assay coefficient of variation (CV) was 3.8 and the between-assay CV was 7.2%. Mean plasma GH concentration in normal dogs was 1.92 +/- 0.14 ng/ml (mean +/- SEM). GH levels in acromegalic dogs were appreciably higher. Insulin-induced hypoglycaemia, arginine and ornithine administration resulted in inconsistent and sluggish GH increment. A better response was obtained by injecting a low dose of clonidine. Clonidine administration to hypopituitary dogs resulted in absent or poor GH increment.
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PMID:Radioimmunoassay of canine growth hormone. 730 77

The present study demonstrates the in vitro and in vivo adsorption of peroxidase onto titanium surfaces. Titanium foils (mean +/- SEM: 365 +/- 2 mm(2), n = 114) were incubated during 30 min with lactoperoxidase (4 mg in 5 mL 100 mM phosphate buffer pH 7). After 15 washings by H(2)O, titanium foils were incubated with o-phenylenediamine (6 mg/mL) and H(2)O(2) (7 mM) during 30 min. The reaction was then stopped by the addition of HCI 1M and the absorbance of the liquid phase was read on a spectrophotometer at 492 nm. In vitro adsorbed lactoperoxidase onto titanium surfaces was 0.70 +/- 0.05 ng/mm(2) (mean +/- SEM, n = 30). X-ray photoelectron spectroscopy confirmed the incorporation of protein nitrogen onto titanium surfaces: the nitrogen atomic percentage increased from 0.9 +/- 0.3 to 12.7 +/- 0.2% (n = 3) and from 3.7 +/- 0.1 to 14.4 +/- 0. 4% (n = 5) when titanium foils were incubated in the lactoperoxidase solution during 30 min and 24 h respectively. In vivo, oral peroxidases adsorbed on titanium healing abutments from 0.01 to 0.58 ng/mm(2) (n = 19) after 2 weeks in the oral environment.
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PMID:Adsorption of peroxidase on titanium surfaces: A pilot study. 1100 26