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Biomedical subjects

S J Soldin

Publications and source records attributed to S J Soldin.

At least 19 recordsLinked to original sources
PubMed1995

Evaluation of the Technicon Immuno I random access immunoassay analyzer and calculation of pediatric reference ranges for endocrine tests, T-uptake, and ferritin.

OBJECTIVES: Evaluation of the precision, accuracy, and user-friendliness of the Technician Immuno I. Calculation of pediatric reference ranges for ferritin and endocrine tests run on Immuno I. METHODS: Precision and accuracy were measured using controls and method comparison studies. Pediatric reference ranges were calculated by comparing the Immuno I results for 100 patients with those of the Abbott IMx and TDx. The regression equation obtained was then used to convert the IMx and TDx reference ranges to reference ranges for the Immuno I. RESULTS: The Immuno I provided both accurate and precise measurement of drugs and endocrine hormones. Pediatric reference ranges were obtained for ferritin and all endocrine tests. CONCLUSION: The Immuno I is user-friendly and provides reliable measurement of both the drugs tested and endocrine tests on a micro-sample. Reagent and curve stability are excellent.

Adolescent↗
PubMed1995

Plasma erythropoietin reference ranges in children.

Plasma erythropoietin values were determined in 1122 hospitalized and outpatient children aged 1 to 18 years with a commercially available enzyme-linked immunosorbent assay. A computerized approach based on the Hoffman technique was used to establish erythropoietin reference ranges. Plasma erythropoietin values ranged from 1.0 to 21.9 mIU/ml in male subjects, and from 1.1 to 20.5 mIU/ml in female subjects (2.5th to 97.5th percentiles).

Adolescent↗
PubMed1995

Serial lecithin/sphingomyelin ratios and surfactant/albumin ratios in tracheal aspirates from term infants with respiratory failure receiving extracorporeal membrane oxygenation.

Serial tracheal aspirate samples were obtained for determination of lecithin/sphingomyelin (L/S) ratios from 47 term infants in respiratory failure. Phospholipids were extracted with Folch solution (chloroform:methanol, 2:1 by vol) and analyzed by HPLC with use of silica column and a mobile phase of acetonitrile:methanol:water (48:31:21, by vol). Surfactant/albumin (S/A) ratios were determined with the TDx Fetal Lung Maturity Assay (Abbott Labs). L/S ratios increased significantly over time in all patients (F = 19.42, P < 0.0001). The S/A ratio correlated with the L/S ratio (r = 0.554, P < 0.001). This study suggests that postnatal surfactant deficiency in term newborns with respiratory failure is a component of the newborn's lung injury.

Albumins↗
PubMed1994

Identification of a 14 kDa FK-506/rapamycin binding immunophilin from calf thymus.

Specific binding proteins (immunophilins, 12-17 kDa) have been described in the cytosol for the immunosuppressant drugs cyclosporine, FK-506, and rapamycin. We describe the identification of a low abundant minor immunophilin (14 kDa) from calf thymus. Saturation experiments using dihydro[3H]-FK-506 gave a Kd of 2 nM and the Bmax of 72 nmol/mg protein. At saturation, 71.3 nmol of FK-506 is bound per mg of the 14 kDa protein (71 nmol) giving a drug/protein ratio of 1.0. Competition experiments using 3H-dihydro FK-506 and rapamycin showed displacement of rapamycin, with Kd in the range of 40 nM. The 14 kDa immunophilin does not have peptidyl-prolyl cis-trans isomerase activity with any of the four substrates investigated. Initial amino acid analysis and protein sequencing data indicate that the immunophilin is different from both the 12 kDa FK-506 binding protein and any other known protein.

Amino Acid Isomerases↗
PubMed1994

Partial characterization of a 52 kDa CsA/FK506/rapamycin binding protein.

Identification and characterization of the cellular proteins that specifically bind to the immunosuppressive drugs, cyclosporine (CsA), FK506, and rapamycin is necessary to understand their mechanism of action. We have isolated and partially characterized a 52 kDa binding protein (BP) from calf thymus. Using 12 peptide substrates we observed very low or no cis-trans peptidyl prolyl isomerase activity. We further tested the protein for catalytic activity including kinase activity, phosphatase activity, protein kinase C regulation, and LCK tyrosine kinase regulation. The 52 kDa BP was capable of blocking the cyclic AMP dependent, protein kinase mediated, phosphorylation of histones and casein. The protein did not demonstrate kinase activity, nor did it affect the activity of protein kinase C or LCK tyrosine kinase. Microsequencing of the 52 kDa BP was performed. A comparison of known sequences indicated that the protein is unique and has not been previously characterized.

Amino Acid Isomerases↗
PubMed1993

Immunophilin receptors for immunosuppressive drugs.

The major immunophilins that bind cyclosporine (cyclophilin) and FK-506/rapamycin (FK-BP 12) have been well characterized. They possess rotamase activity, which is inhibited by the immunosuppressant that binds to them. The immunosuppressive action does not appear to be coupled to rotamase activity. The literature is reviewed on some possible mechanisms of immunosuppression. Minor immunophilins of 14, 36, and 52 kDa have also been isolated and partially characterized. Receptor assays employing immunophilins have been developed.

Animals↗
PubMed1992

Bentiromide test using liquid-chromatographic measurement of p-aminobenzoic acid and its metabolites for diagnosing pancreatic insufficiency in childhood.

We assessed the diagnostic capability of the bentiromide test using a high-pressure liquid-chromatography method to analyze p-aminobenzoic acid and its metabolites in plasma as an indirect measure of exocrine pancreatic function. Mean total amine concentration in pancreatic-insufficient subjects was significantly lower than in control subjects. There were 3 of 15 false-negative results and no false-positive results. We conclude that this chromatographic method is an effective means of analyzing p-aminobenzoic acid and its metabolites after ingestion of bentiromide.

4-Aminobenzoic Acid↗
PubMed1992

Development of a radioreceptor assay to measure glucocorticoids.

We have developed a radioreceptor assay to measure glucocorticoids. The assay employs the partially purified 95-kDa receptor isolated from human liver and purified by size fractionation on high-performance liquid chromatography (HPLC). In the assay [3H]prednisolone competes with steroids (endogenous and exogenous) for binding to the receptor. Bound and free are separated by treatment with charcoal. The between-day precision [% coefficient of variation (CV)] at concentrations of 9.4, 18.7, and 69.9 micrograms/L prednisolone is 16.6, 9.3 and 4.5%, respectively. Specificity studies revealed that hydrocortisone, deoxycorticosterone, 4-pregnene-17 alpha,21-diol-3,20-dione, 17 alpha-hydroxyprogesterone, corticosterone and beta-hydroxyprogesterone all compete with [3H]prednisolone for binding to the receptor. Prednisone and 6 alpha-methyl prednisolone displace [3H]prednisolone to only a minor degree. The assay has been used to assess "glucocorticoid activity" in children with rheumatic diseases treated with prednisolone.

Charcoal↗
PubMed1992

Use of a radioreceptor assay in the assessment of cushingoid features in patients with juvenile rheumatic diseases.

A marked variation has been observed in severity of cushingoid appearance in patients with rheumatic diseases (RD) following steroid administration. We studied ten children with RD to determine if a relationship exists between cushingoid features and an individual's steroid activity as measured by prednisolone equivalents using a radioreceptor assay. Cushingoid features were clinically assessed by a "cushing score" according to the method of Bergrem. Patients were assigned to either the cushingoid (C) or noncushingoid (NC) group at study entry according to their cushing score. Blood was drawn prior to prednisone ingestion and then at 30, 60, 90, 120, 240, and 360 minutes and each sample was assessed for prednisolone equivalents and also for free and total cortisol. Group comparisons of dose-adjusted area under curve (AUC) and peak response are reported. Cushingoid patients had higher plasma prednisolone equivalents (PE) than noncushingoid patients as measured by peak PE and AUC. The PE.6 h/L average AUC for C patients was 248 micrograms PE.6 h/L versus 134 micrograms PE.6 h/L for NC patients. This nearly twofold difference was also noted between mean peak values (C 82 micrograms/L vs. NC 44 micrograms/L). Spearman correlations of Cushing scores with these two parameters indicated significant (p less than 0.05) relationships. A patient's Cushing score correlated best with peak response (rs = 0.78) and also with AUC (rs = 0.72). Measurement of plasma peak PE or AUC could be valuable for individualizing steroid dosing in children with RD.

Adolescent↗
PubMed1992

Preliminary studies on the in vitro and in vivo effect of salicylate on sperm motility.

We have studied the in vitro effect of different concentrations of salicylic acid on the motility of normal human spermatozoa. Sperm motility was evaluated over 48 h at 0, 50, 100, and 200 mg/L of salicylate concentrations. Results are reported as the mean % motility, where 100% motility at each time interval was taken to be the motility of the control (0 mg/L of salicylate). At 48 h, the mean % motility (n = 12) was 61, 43, and 33% at 50, 100, and 200 mg/L of salicylate. Twenty-four-hour values (n = 17) were 75, 65, and 48%. Eosin supravital staining demonstrated that the decrease in sperm motility was caused by direct inhibition of motility rather than by spermatozoal death. Four healthy males (17-51 years of age) gave a semen specimen prior to taking 650 mg of salicylate four times daily, followed by a second semen specimen 72 h later. Each individual, therefore, served as his own control. The mean % motility in the postdrug sample at 2, 24, and 48 h was 49, 53, and 47% of the motility found in the predrug sample (n = 4). We conclude that salicylate significantly decreases sperm motility in vitro and in vivo.

Adolescent↗
PubMed1992

Organic acids interfere in the measurement of carbon dioxide concentration by the Kodak Ektachem 700.

A significant discrepancy was noted in our laboratory between the total plasma carbon dioxide concentration measured by the Kodak Ektachem 700 and the bicarbonate concentration derived from the Corning 170 pH/Blood Gas analyser in an 8-day-old patient. The concentration of total carbon dioxide was 18 mmol/L while the derived bicarbonate was 13 mmol/L. The patient was eventually diagnosed as maple syrup urine disease. This finding led us to examine the effect of various organic acids on the measurement of carbon dioxide by the Ektachem 700. Several interfered significantly. Clinicians should be aware that when organic acid concentrations are increased, the Ektachem 700 total carbon dioxide result may be falsely raised.

Blood Gas Analysis↗
PubMed1992

Radioreceptor assay for quantifying FK-506 immunosuppressant in whole blood.

We describe a quantitative radioreceptor assay (RRA) for quantifying FK-506 in whole blood. FK-506 extracted from whole blood with a cyclohexyl-sorbent column competes with [3H]dihydro-FK-506 for binding to a partially purified preparation of FK-506 binding protein (FK-BP). Free and protein-bound FK-506 are separated on LH 20 Sephadex chromatographic columns. We compared the results of this method with those of an enzyme immunoassay that uses a monoclonal antibody: r = 0.97, Sy/x = 0.039. Between-day precisions (CV) at FK-506 concentrations of 8 and 17 micrograms/L were 9.2% and 8.2%, respectively. Within-run precisions were 5.9%, 8.1%, and 9.4%, respectively, at 4, 8, and 15 micrograms/L. Analytical recovery, evaluated at 5, 10, 15, 20, and 25 micrograms/L for FK-506 added to whole blood, ranged from 98% to 103%. The assay can reliably quantify FK-506 blood concentrations between 1.0 and 25 micrograms/L.

Chromatography, High Pressure Liquid↗
PubMed1991

Purification and characterization of cyclosporine and FK-506 binding proteins from a human T-helper cell line.

Cytosolic proteins that specifically bind cyclosporine A and FK-506 were isolated and purified from the JURKAT human T-helper cell line. These binding proteins were purified by affinity, molecular weight exclusion and weak cation exchange column chromatography. Radiolabeled cyclosporine A specifically bound to a approximately 17 kDa molecule which is cyclophilin and also bound to a approximately 50 kDa protein(s). Radiolabeled FK-506 did not bind to the approximately 17 kDa molecular weight protein, but specifically bound to soluble approximately 10 kDa and approximately 50 kDa proteins.

Amino Acid Isomerases↗
PubMed1991

Correlation of cyclosporine and metabolite binding to cyclophilin and a 50 kDa binding protein with in vitro immunosuppression: a preliminary report.

Seven purified cyclosporine (CsA) metabolites were analyzed for binding to cyclophilin and to a 50 kDa protein purified from a JURKAT cell line. In addition, the potency of the seven metabolites, relative to CsA, was obtained using a primary mixed lymphocyte culture (MLC) suppression assay. CsA, M1, 17, and 21 were found to be immunosuppressive in the concentration range used (0-500 ng/mL). These results were then compared to protein binding. CsA and metabolite 17 (M17) bound to both proteins. Conversely, M1, 13, 21, and 26 bound only to cyclophilin, while M8 and M18 bound only to the 50 kDa protein.

Amino Acid Isomerases↗
PubMed1991

A preliminary study to evaluate an in vitro assay for determining patient whole blood immunosuppressive cyclosporine A and metabolite activity: comparison with cytosolic binding assays using cyclophilin or a 50-kilodalton binding protein, and the Abbott TDx cyclosporine A parent, and parent and metabolites assays.

Thirty-five allograft recipients undergoing cyclosporine A (CsA) therapy were randomly selected to evaluate a "novel" in vitro assay that determines CsA and metabolite immunosuppressive activity in whole blood. The assay uses a third party mixed lymphocyte culture (MLC) system to which patient whole blood extracts containing CsA and metabolites are added. The ability of the extracted CsA and metabolites to inhibit proliferation in this system is proportional to the immune suppressive activity in whole blood. Comparison of the MLC suppression assay against Abbott TDx parent, TDx parent and metabolites, and radioreceptor assays utilizing cyclophilin or a 50-kDa binding protein isolated from JURKAT cytosol gave the following correlation coefficients: r = 0.612, r = 0.672, r = 0.362, and r = 0.775, respectively.

Amino Acid Isomerases↗