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Biomedical subjects

D E Goldstein

Publications and source records attributed to D E Goldstein.

At least 55 records · Page 3Linked to original sources
PubMed1985

Measurement of glycosylated whole-blood protein for assessing glucose control in diabetes: collection and storage of capillary blood on filter paper.

We present data on the use of filter-paper blood collection for measurement of glycosylated whole-blood proteins (gWB) (hemoglobin and plasma proteins). A capillary blood sample, obtained by fingerprick, is spotted directly onto filter paper (Schleicher & Schuell 903). The blood spot is washed briefly with alcohol (ethanol or isopropanol) to remove free glucose and dried before shipment to the laboratory. In the laboratory, the blood is eluted from the paper and analyzed for gWB by a colorimetric method. The gWB is primarily a measure of glycosylated hemoglobin (gHb) with a small contribution from glycosylated plasma protein. Concentrations of gWB and gHb are highly correlated (r = 0.91). The filter-paper method offers advantages over currently available methods for quantifying gHb and may be particularly useful in screening for diabetes and for assessing glycemic control in patients from remote areas.

Blood Proteins↗
PubMed1984

A comparative evaluation of glycosylated haemoglobin assays: feasibility of references and standards.

Four assays, high pressure liquid chromatography, colorimetric with thiobarbituric acid, affinity columns, and microcolumn cation exchange were compared for ability to discriminate between samples taken from diabetic and normal subjects; correlation with each other; stability over time at different temperatures; and reproducibility between laboratories. The most discriminatory (10 samples from a diabetic and 10 samples from a normal group) was the microcolumn cation exchange method (t = 5.25; p less than 0.001), but all were significantly different at p less than 0.005. The intra-assay coefficient of variation was 1%-6%, except for the affinity column method which was 13% in normal subjects. High pressure liquid chromatography was used as a reference and the other assays correlated well (r = 0.93-0.99). Storage at -80 degrees C, -20 degrees C, 4 degrees C, and 24 degrees C showed marked differences. The thiobarbituric acid method results were stable except for 24 degrees C. Microcolumn cation exchange was labile under all conditions. Affinity column was stable for up to 15 days, only if samples were stored as whole blood. High pressure liquid chromatography showed an increase in haemoglobin A1a + b and a decrease in the haemoglobin A1c. Haemoglobin A1c was reproducible for 4 days when stored at 4 degrees C and up to 11 days when stored at -80 degrees C. Samples exchanged between centres at 4 degrees C and performed within 5 days by high pressure liquid chromatography for haemoglobin A1 and haemoglobin A1c correlated well (r = 0.98 and 0.99). Samples exchanged between centres after storage (up to 40 days -80 degrees C) correlated (r = 0.99) by the thiobarbituric acid method.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Affinity↗
PubMed1984

Recent advances in glycosylated hemoglobin measurements.

Glycosylated hemoglobins have gained wide acceptance as an accurate index of long-term blood glucose control in diabetes mellitus. A variety of glycosylated hemoglobin assays is available. There is a high degree of correlation between results determined by these assays. The ideal laboratory method for measuring glycosylated hemoglobin in the diabetic should be accurate, precise, easily standardized, inexpensive, and rapidly performed. Unfortunately, none of the currently used methods meet all of the criteria necessary to be considered the ideal laboratory method. The most widely used methods for quantitating glycosylated hemoglobins--including ion exchange chromatography, electrophoresis, isoelectric focusing, thiobarbituric acid colorimetry, and affinity chromatography--are reviewed with respect to the important advantages and disadvantages of each method for the clinical laboratory. Techniques for quantitating glycosylated proteins other than hemoglobins, such as albumin, are also discussed.

Blood Specimen Collection↗
PubMed1983

Glycosylated hemoglobin measured by affinity chromatography: micro-sample collection and room-temperature storage.

Under proper conditions, whole blood can be stored at room temperature for as long as 21 days before measurement of glycosylated hemoglobin by affinity chromatography. Whole blood (anticoagulated with EDTA or heparin) was placed in capillary tubes, which were then sealed at both ends and stored at room temperature. Just before assay, whole blood was rinsed from the tubes and diluted 10-fold with water. Samples of each patient's blood were assayed as whole-blood hemolysates by affinity chromatography after zero, seven, 14, and 21 days of storage. Values for glycosylated hemoglobin did not change over 21 days of storage and values for each storage day correlated well (r = 0.97, p less than .0001) with hemoglobin A1C measured in fresh erythrocyte hemolysates by "high-performance" liquid ion-exchange chromatography.

Blood Specimen Collection↗
PubMed1983

Effects of whole blood storage on results for glycosylated hemoglobin as measured by ion-exchange chromatography, affinity chromatography, and colorimetry.

After storage of whole blood at either 4 or 20 degrees C, results for glycosylated hemoglobin by ion-exchange chromatography ("high-performance" liquid and mini-column chromatography), thiobarbituric acid colorimetry, and affinity chromatography were compared. At 4 degrees C, all methods gave acceptable results for samples stored for as long as a week. At 20 degrees C, the colorimetric and affinity methods also showed sample stability for a week or more. The ion-exchange methods were associated with a marked increase in values for glycosylated hemoglobin after a few days of storage. Evidently, care in details of sample collection and handling is especially important for ion-exchange methods, and the colorimetric and affinity methods have advantages over ion exchange in situations where long delays between sample collection and assay are unavoidable.

Blood Preservation↗
PubMed1983

Effect of inhaled beclomethasone dipropionate on hypothalamic-pituitary-adrenal axis function in children with asthma.

The hypothalamic-pituitary-adrenal axis was investigated in 15 asthmatic children treated with inhaled beclomethasone dipropionate (mean 490 micrograms/day) and 11 asthmatic control subjects receiving no corticosteroid therapy. Measurements of 24-h urinary free cortisol and 17 hydroxy corticosteroids, serum cortisol, response to ACTH, and the oral metyrapone test showed no significant difference between the two groups. All the patients' results were within normal limits, and carbohydrate metabolism, as shown by blood glucose and hemoglobin A1c, was not affected by beclomethasone therapy. Thus, in the above dose, inhaled beclomethasone does not cause suppression of the hypothalamic-pituitary-adrenal axis.

17-Hydroxycorticosteroids↗
PubMed1982

Glycosylated hemoglobin in Mystromys albicaudatus: a diabetic animal model.

Glycosylated hemoglobin was measured in Mystromys albicaudatus, a rodent model of diabetes mellitus, using a newly developed colorimetric assay. The mean glycosylated hemoglobin for non-diabetic Mystromys (n = 321) was 14.8 nmol hydroxymethylfurfural / 10 mg hemoglobin which is similar to that obtained in non-diabetic humans. Animals with a glycosylated hemoglobin value greater than 19 nmol hydroxymethylfurfural / 10 mg hemoglobin were characterized as diabetics. Significant correlations were found between glycosylated hemoglobin and both plasma glucose and urine glucose levels.

Animals↗
PubMed1982

Determination of glycosylated hemoglobin by affinity chromatography: comparison with colorimetric and ion-exchange methods, and effects of common interferences.

An affinity-chromatographic method for determination of glycosylated hemoglobin (Anal. Lett. 14: 649-661, 1981) is compared with the thiobarbituric acid colorimetric (I) (Clin. Chem. 27: 669-672, 1981) and the ion-exchange liquid-chromatographic (II) (Diabetes 29: 623-628, 1980) methods. A correlation of 0.98 was obtained for the affinity method vs II and 0.97 for affinity vs I (n = 51). The within-run CV was 1.9% for specimens from non-diabetic individuals and 1.0% for those from diabetics. The respective between-run CVs were 3.4% and 2.4%. Failure to remove "labile" glucose adducts by 5-h incubation of erythrocytes in isotonic saline (37 degrees C) contributed an average error of 13.1% for II, 5.4% for I, and 1.6% for the affinity method. Affinity chromatography gave a decrease of 0.1-0.2% glycosylated hemoglobin for each 1.0 degree C temperature increase between 18 and 27 degrees C. Varying the pH of the wash buffer used in the affinity procedure from 7.75 to 8.25 (pH 8.0 optimum) produced at net change of 0.5% in glycosylated hemoglobin with one diabetic specimen. Using the affinity method, we determined the reference interval for glycosylated hemoglobin in 124 apparently healthy individuals to be 5.3 to 7.5% (mean 6.36%, SD 0.55%). Rechromatography by II and isoelectric focusing analysis of the fractions obtained by the affinity separation revealed a substantial population of glycosylated hemoglobins not measured by II. The affinity method offers a rapid, simple, precise, and accurate alternative to methods currently in use and gives substantial freedom from many common interferences.

Adolescent↗
PubMed1981

Improved colorimetric assay for glycosylated hemoglobin.

This colorimetric assay for glycosylated hemoglobin can be performed in 120 min with equipment available in most clinical laboratories. The glucose moiety of glycosylated hemoglobin is converted to 5-hydroxymethylfurfural by heating with oxalic acid for 60 min is an autoclave at 124 degrees C and 124 kPa (18 lb/in.2). The adduct formed by reacting 2-thiobarbituric acid with hydroxymethylfurfural is measured photometrically and results are expressed either as nanomoles of hydroxymethylfurfural or as fructose equivalents. Within-assay and between-assay coefficients of variation were less than 2% and less than 3%, respectively. Comparison of results for 50 patients' specimens as measured by the present assay and as analyzed for hemoglobin A1c by liquid chromatography showed excellent correlation (r = 0.98).

Chromatography, High Pressure Liquid↗
PubMed1980

Impaired glycogen synthase activating system in human diabetic polymorphonuclear leukocytes.

The effects of diabetes mellitus on glycogen synthase and its activating system (synthase phosphatase) were studied using human polymorphonuclear leukocytes (PMN). PMN were obtained from control subjects and diabetic patients by a gradient sedimentation technique. Enzyme activities of endogenous synthase-l and total synthase were not statistically different in diabetic and control cells. For measurement of endogenous synthase phosphatase, cells were sonicated in 50 mM Tris buffer (pH 7.5) and incubated at 30 degrees C. Conversion of synthase-D to -l and the maximum percent synthase-l attained were decreased in homogenates of diabetic cells. There was no correlation between the plasma glucose concentration and the rate of conversion of synthase-D to -l. Synthase phosphatase activities were also measured using a purified synthase-D substrate. Under these experimental conditions, glycogen synthase phosphatase activities did not differ in control and diabetic cells. These results are consistent with a diabetes-induced defect in conversion of endogenous synthase-D to -l at the level of the synthase enzyme rather than at that of the activating phosphatase.

Adolescent↗
PubMed1978

Effect of starvation on hepatic glycogen metabolism and glucose homeostasis.

The effects of starvation on the hepatic glycogen synthase and phosphporylase systems were sequentially assessed in fed and 24-120-hr-fasted rats. Enzymic changes before and after glucose were correlated with simultaneous measurements of hepatic cyclic AMP and glycogen concentrations and glucose, insulin, and glucagon concentrations in the portal vein plasma. Fasting caused parallel changes in plasma glucose and hepatic glycogen concentrations with decreases by 24 hr and subsequent increases, which correlated with increases in hepatic synthase l and decreases in phosphorylase activites. Hepatic cyclic AMP levels increased as 24-48 hr, decreased below fed levels at 96 hr, and increased again at 120 hr. Fasting caused progressive impairment of glucose disposal, decreased basal and postglucose insulin concentrations, and decreased basal glucagon levels at 48-72 hr. Hepatic synthase l increments following glucose were exaggerated in 48-120-hr-fasted rats, although consistent phosphorylase decrements were seen only in fed rats. There was no clearcut relationship between synthase activation and phosphorylase inactivation following glucose in fed or fasted rats.

Animals↗
PubMed1978

Altered mechanism of glucagon-mediated hepatic glycogenolysis during long-term starvation in the rat.

The effect of long-term starvation on glucagon-mediated hepatic glycogenolysis was investigated in the rat in vivo. Following glucagon (50 microgram/kg i.v.) fed rats showed rapid phosphorylase activation but no change in synthase-I activities. In contrast, rats fasted 72 hr (long-term fasting) showed rapid synthase inactivation but no significant phosphorylase activation. Rats fasted 24 hr (short-term fasting) demonstrated coordinated inactivation of synthase and activation of phosphorylase. Hepatic cyclic AMP responses were greater in fasted rats. Hepatic glycogen concentrations in rats fasted 72 hr were approximately 30% of fed levels. After glucagon, comparable decrements in hepatic glycogen and increments in plasma glucose concentrations were seen in fed and 72-hr groups. The diminished responsiveness of the hepatic phosphorylase system in rats fasted 72 hr was not attributable to altered cyclic AMP-dependent protein kinase or phosphorylase kinase activities. However, the diminished responsiveness could be ascribed to diminished total phosphorylase with nearly complete activation in the basal state. In fed and fasted rats, synthase decrements after glucagon correlated closely with basal levels of synthase-I. Thus, it is proposed that the enzymatic mechanism of glucagon-mediated hepatic glycogenolysis differs in fed and fasted rats. It is also proposed that partial hepatic glycogen reaccumulation during long-term fasting could be physiologically important for glucose homeostasis.

Animals↗