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Biomedical subjects

F A Sedor

Publications and source records attributed to F A Sedor.

At least 19 recordsLinked to original sources
PubMed1999

Cardiac troponin T levels in umbilical cord blood.

OBJECTIVE: We sought to determine cardiac troponin T concentrations in umbilical cord plasma from normal and complicated pregnancies. STUDY DESIGN: At the time of delivery, umbilical cord arterial and venous samples were collected from 209 neonates, and cardiac troponin T levels were measured by immunoassay. Comparisons of clinical factors were made between neonates with normal and elevated cardiac troponin T levels. Significance was deemed present at P <.05. RESULTS: Twelve neonates had elevated cardiac troponin T levels. Exposure to magnesium sulfate was associated with an elevated cardiac troponin T level (relative risk, 33.2; 95% confidence interval, 7.7-143). CONCLUSIONS: Cardiac troponin T levels were elevated in neonates exposed to magnesium sulfate in utero. The explanation of this finding and its clinical significance are unknown. Characterization of fetal and neonatal troponin T requires further study.

Adult↗
PubMed1996

Evaluation of the YSI 2300 glucose analyzer: algorithm-corrected results are accurate and specific.

OBJECTIVES: To insure commutability (equivalence) between whole blood and plasma glucose values and to assess potential interferences in glucose oxidase methods. DESIGN AND METHODS: We compared plasma glucose results by the Ektachem 700 analyzer to glucose results on whole blood by the Nova Stat Profile 6, and by the YSI 2300, both without hematocrit correction (YSIunc) and with two different hematocrit (Hct) corrections. The two correction methods were: (a) whole blood results multiplied by 1.11 (YSI1.11), and (b) whole blood results corrected for Hct with the programmed YSI algorithm (YSIcor). Several compounds were tested for interference. RESULTS: 88% of YSIcor results agreed with plasma results within plus/minus 5%, and 78% of Nova and 74% of YSI1.11 results were within this limit. YSIcor results were unaffected by Hct and were valid even when erythrocyte size was abnormal. At low Hct, Nova results were falsely decreased, while YSI1.11 results were falsely elevated. The Ektachem was most affected by ascorbic acid, and the Nova was especially affected by acetaminophen. CONCLUSIONS: The YSI algorithm-corrected whole blood glucose results were commutable with plasma results and the YSI was unaffected by the compounds tested, including acetaminophen and acetylsalicylic acid.

Algorithms↗
PubMed1996

Adaptation of a quantitative immunoassay for urine myoglobin. Predictor in detecting renal dysfunction.

Myoglobinuria, subsequent to rhabdomyolysis, may cause acute renal failure. For this reason, many qualitative and quantitative tests have been developed for the detection of myoglobin in urine. The authors describe the adaptation and optimization of the Stratus II serum myoglobin immunoassay to quantify urine myoglobin. In addition, the assay was used to accurately determine urine myoglobin concentrations in subjects at potential risk for myoglobin-induced renal dysfunction and the results obtained compared to conventional qualitative methods for urine myoglobin. The assay demonstrated with-in run and between-run coefficient of variations (CVs) of 6.2% and 7.2%, respectively, was linear from 0-950 micrograms/L, demonstrated good recovery, and was free from interference by hemoglobin, creatinine, and urea. Specimens were diluted with 0.1 mol/L phosphate buffer, pH 9.0 containing 3% bovine serum albumin before analysis. Myoglobin was assayed on urine obtained from 30 patients suspected of having myoglobinuria. Fifteen of 17 patients with serum creatinine greater than 1.4 mg/dL had myoglobin concentrations greater than 20,000 micrograms/L, whereas the remaining 31 patients with normal serum creatinine had urine myoglobin concentrations of less than 18,000 micrograms/L. If serum creatinine is used as an indicator of renal function, it would appear that accurate measurement of urine myoglobin may facilitate identification of patients with increased susceptibility to myoglobin-induced acute renal failure.

Acute Kidney Injury↗
PubMed1996

Ultrafiltration discrepancies in recovery of myoglobin from urine.

We investigated the efficiency, accuracy, and reliability of the ultrafiltration/dipstick methodology commonly used to diagnose myoglobinuria. Twenty-five myoglobin-containing urine specimens were filtered by centrifugation for 15 min at 1500g through a Centricon-30 membrane filter. Both the original specimen and filtrate were assayed for myoglobin. The amount of myoglobin recovered subsequent to filtration varied from <1-38%. This poor and variable recovery was independent of sample matrix or precentrifugation of the specimens. This was most critical for urine specimens with myoglobin concentrations <60 000 microg/L. Fourteen of 18 such filtrates had concentrations <350 microg/L, a concentration below which a negative result would be obtained by using conventional dipstick methods. Thus, the use of this procedure has the potential to misdiagnose patients with myoglobin concentrations associated with increased risk of subsequent renal dysfunction, in particular when urine myoglobin concentrations are <60 000 microg/L.

False Negative Reactions↗
PubMed1996

Pneumatic transport exacerbates interference of room air contamination in blood gas samples.

OBJECTIVE: To characterize and control the potential interference to P(O2) determinations when blood contaminated with air is sent via a pneumatic tube system (PTS). DESIGN: Both tonometered blood at P(O2)s of 65, 75, 142, and 339 mm Hg and arterial blood gas samples from patients with baseline P(O2)s from 70 to 400 mm Hg were analyzed for P(O2) to determine possible effects of air contamination from PTS transport. SETTING: A large teaching hospital in which a variety of personnel routinely send samples to the laboratory by PTS transport. PATIENTS: Twenty patients under anesthesia for elective surgery and 21 patients in an intensive care unit who had a wide range of P(O2)s. Several additional patients with a preexisting lung pathology likely to cause hypoxemia were selected to provide samples with low P(O2)s. MAIN OUTCOME MEASURES: Measurement of bias in P(O2) between samples sent via PTS and samples walked to the laboratory. RESULTS: Interference from air contamination was worse after PTS transport compared with manual transport of the specimen. Over a wide range, the P(O2) in specimens after PTS transport tended toward 160 mm Hg. Samples from hypoxemic patients were prone to errors in P(O2) that could have resulted in clinical misinterpretation; 5 of 10 samples with a baseline P(O2) less than 85 mm Hg had increases of 10 mm Hg or more when contaminated with air. Cooling samples with high P(O2)s minimized changes to P(O2), probably by increasing the solubility of oxygen. Mechanical buffering by various liners used in the carriers did little to alleviate the interference. Decreasing the speed of pneumatic transport by 50% lessened the effect on P(O2). CONCLUSION: Interference can be minimized by carefully purging samples of all air bubbles using the following protocol: invert syringe to check for air bubbles, then retap and reexpel bubbles if necessary. Personnel that collect and send blood gas samples via PTS should be educated about the problem of interference. Modifications both to pneumatic sample transport systems and to blood gas syringes should be investigated to minimize the effect.

Air↗
PubMed1995

Intracellular magnesium content of mononuclear blood cells and granulocytes isolated from leukemic, infected, and granulocyte colony-stimulating factor-treated patients.

The intracellular magnesium (Mg) concentration of granulocytes and mononuclear blood cells (MBCs) was determined in cells isolated from patients with several disorders. The mean (+/-SD) Mg content of MBCs isolated from patients diagnosed with lymphocytic leukemia, myelocytic leukemia, or infection; from patients treated with granulocyte colony-stimulating factor (G-CSF); and from healthy volunteers (control group) was 2.3 (+/-0.6), 3.3 (+/-0.5), 4.1 (+/-0.8), 3.9 (+/-0.4), and 3.9 (+/-0.6) fmol/cell, respectively. The Mg content of MBCs isolated from patients with lymphocytic and myelocytic leukemia, but not those from patients with infection or receiving G-CSF treatment, were significantly lower (P < 0.001) than those from the control subjects. The mean Mg concentration of granulocytes obtained from lymphocytic leukemia, myelocytic leukemia, infection, and G-CSF patients and from the control group was 3.2 (+/-0.9), 3.4 (+/-0.5), 3.8 (+/-0.6), 4.5 (+/-0.6), and 4.6 (+/-0.6) fmol/cell, respectively. Granulocytes isolated from leukemic and infectious patients yielded lower intracellular Mg concentrations (P < 0.005) than those from patients receiving G-CSF and the control group. This study demonstrates that intracellular Mg content is altered in several pathological states. Several factors, including depleted Mg stores or altered intracellular Mg binding sites, could be responsible for these changes. Apparently, intracellular Mg content may be of use in assessing total body Mg status.

Granulocyte Colony-Stimulating Factor↗
PubMed1995

Artifactual hypoglycemia associated with hematopoietic cytokines.

We observed apparent hypoglycemia in seven patients manifesting granulocytosis associated with hematopoietic cytokine treatment or with a leukemoid reaction. All seven patients had confounding preanalytic conditions of specimen transport delay and lack of antiglycolytic agents. Cytokine-stimulated leukocytes may cause artifactual hypoglycemia by consuming glucose in vitro, possibly leading to unnecessary diagnostic evaluation. The glucose depletion was faster in blood drawn from patients receiving granulocyte colony-stimulating factor (0.29 mmol/L/h) than in blood from a control group (0.17 mmol/L/h) or from a group with leukemia (0.23 mmol/L/h). Stabilization with sodium fluoride (60 mmol/L) slowed the glucose depletion in both the cytokine group (0.13 mmol/L/h) and the leukemic group (0.09 mmol/L/h), which were then statistically indistinguishable from the control rate (0.10 mmol/L/h). In blood obtained from patients being treated with hematopoietic cytokines or who have leukemoid reactions, an antiglycolytic agent should be used whenever separation of plasma might be delayed more than 1 hour.

Artifacts↗
PubMed1988

Reflotron cholesterol measurement evaluated as a screening technique.

We evaluated the analytical performance of Boehringer Mannheim Diagnostics' "Reflotron" analyzer for the measurement of cholesterol. Coefficients of variation (CVs) for whole-blood cholesterol were: within-day 2.0% and 2.2% at 1680 and 2670 mg/L, respectively; between-day 1.8% and 2.4% (n = 9 and 8). Results were similar for serum and heparinized or EDTA-treated single-donor plasma (CV 1.4% to 2.6%). CVs of results for two reconstituted commercial quality-control materials were 3.4% and 4.6%. Heparin and hematocrit were evaluated as interferents, and critical limits for interference were identified for bilirubin, hemoglobin, and triglyceride in blood and plasma or serum. When sample collection and analysis were controlled by trained personnel, results with the Reflotron (y) compared well with those by the Ektachem procedure (x) for both blood and serum samples: r = 0.950, y = 0.944x + 130 mg/L; and r = 0.955, y = 0.93x + 43.5 mg/L, respectively. The same comparability was observed when the analysis was performed by briefly trained high-school students: r = 0.980, y = 0.949x + 23 mg/L. Performance decreased when both collection and analysis were performed by laymen: r = 0.880, y = 0.870x + 186 mg/L.

Autoanalysis↗
PubMed1987

Digoxin-like immunoreactivity eliminated from serum by centrifugal ultrafiltration before fluorescence polarization immunoassay of digoxin.

Digoxin determined in the Abbott "TDx" by fluorescence polarization immunoassay by the manufacturer's recommended method involving precipitation of protein with 5-sulfosalicylic acid (SSA) is subject to interference from endogenous compounds having digoxin-like immunoreactivity. Guided by the work of Graves et al. (Clin Chem 1986;32:1506-9), we eliminated interference caused by digoxin-like immunoreactivity by substituting ultrafiltration for precipitation with SSA to remove protein. Using the manufacturer's method, we quantified digoxin in serum from 53 patients in three clinically defined groups who were receiving no digoxin, finding apparent digoxin in excess of the 200 ng/L detection limit in 24% of the 17 pregnant women, 59% of the 17 renal-dialysis patients, and all of 19 neonatal cord-blood samples examined. No measurable digoxin immunoreactivity was observed by fluorescence polarization immunoassay for any of the 53 clinically defined patients after removal of protein by ultrafiltration. For 22 men for whom digoxin was prescribed, digoxin measurement after protein removal by SSA and by ultrafiltration correlated well (r = 0.98), with good proportionality (slope = 1.04). Analytical recovery of added digoxin from adulterated serum was 115% after SSA, but 100% after ultrafiltration. Thus, before this assay procedure, we recommend ultrafiltration, to remove digoxin-like interference.

Digoxin↗
PubMed1984

Hemodynamic and metabolic responses to exercise after alpha 1-, beta 1-, and nonselective beta-adrenoceptor blockade in man.

The effects of acute alpha 1-adrenoceptor blockade with prazosin, beta 1-adrenoceptor blockade with atenolol, and nonselective beta-adrenoceptor blockade with propranolol were compared in a placebo-controlled crossover study. The study involved measurement of the hemodynamic and metabolic responses to exercise after heavy exercise in order to induce skeletal muscle glycogen depletion and thus enhance the dependence on hepatic glucose output and circulating free fatty acids. Catecholamine responses to exercise were enhanced by glycogen depletion and by both beta-blocking drugs. Catecholamine levels were highest with propranolol; as a consequence, at high work loads, propranolol failed to produce a significant reduction in systolic blood pressure and elevated diastolic blood pressure. At high work loads, atenolol reduced systolic blood pressure but did not change diastolic blood pressure. Both beta blockers reduced free fatty acid levels, but only propranolol accelerated the fall of plasma glucose levels during "glycogen-depleted" exercise. In contrast, during exercise prazosin reduced systolic and diastolic blood pressures, and elevated heart rate and plasma catecholamines, particularly noradrenaline. Concomitantly, prazosin raised free fatty acid and lactate levels, and increased the plasma glucose level at a time when placebo therapy resulted in a steady fall in glucose levels. The results indicate important differences in the hemodynamic effects of cardioselective versus nonselective beta-blockade during long-term (or glycogen-depleted) exercise. The importance of beta 2-mediated hepatic glycogenolysis in man is confirmed. Acute alpha 1-blockade with prazosin induces reflex elevation of catecholamine levels. There is no indication of an important role for an alpha 1-mediated mechanism in hepatic glucose production in man.

Adult↗
PubMed1984

Comparison of pyridoxal phosphate-supplemented reagent kits for alanine aminotransferase using centrifugal analysis.

The addition of pyridoxal-5-phosphate for assay of alanine aminotransferase has been recommended. The referral methods are inconvenient for high volume instrumentation due to use of multiple reagents and blanks. We adapted a well-documented method to the centrifugal analyzer as a reference for adaptation of two kit methods. Reference intervals obtained and linearity determined were all similar. The kit methods compared favorably to the referral method. Linear regression analysis yielded the following: DOW = 1.011 BERG + 1.666, r = 0.9965; SKI = 0.938 BERG + 4.559, r = 0.9926; and DSKI = 1.028 BERG + 1.051, r = 0.9889. Precision of the assays was acceptable. We concluded that automation of reagent kits incorporating pyridoxal-5-phosphate is feasible and the assays compared favorably to a recommended method. High volume instrumentation can be used without denigration of analytical quality and to allow comparability to a documented method for interlaboratory review.

Adult↗
PubMed1984

Hemodynamic and metabolic responses to exercise after adrenoceptor blockade in humans.

The effects of acute alpha 1-adrenoceptor blockade with prazosin, beta 1-adrenoceptor blockade with atenolol, and nonselective beta-adrenoceptor blockade with propranolol were compared in a placebo-controlled crossover study of the hemodynamic and metabolic responses to acute exercise 2 h after prolonged prior exercise to induce skeletal muscle glycogen depletion, enhancing the dependence on hepatic glucose output and circulating free fatty acids (FFA). Plasma catecholamines were higher during exercise after, as opposed to before, glycogen depletion and were elevated further by all three drugs. Propranolol failed to produce a significant reduction in systolic blood pressure and elevated diastolic blood pressure. Atenolol reduced systolic blood pressure and did not change diastolic blood pressure. Both beta-blockers reduced FFA levels, but only propranolol lowered plasma glucose relative to placebo during exercise after glycogen depletion. In contrast, prazosin reduced systolic and diastolic blood pressures and resulted in elevated FFA and glucose levels. The results indicate important differences in the hemodynamic effects of beta 1-selective vs. nonselective beta-blockade during exercise after skeletal muscle glycogen depletion. Furthermore they confirm the importance of beta 2-mediated hepatic glucose production in maintaining plasma glucose levels during exercise. Acute alpha 1-blockade with prazosin induces reflex elevation of catecholamines, which in the absence of blockade of hepatic beta 2-receptors produces elevation of plasma glucose. The results suggest there is little role for alpha 1-mediated hepatic glucose production during exercise in humans.

Adrenergic alpha-Antagonists↗
PubMed1983

Differentiation of hemodynamic, humoral and metabolic responses to beta 1- and beta 2-adrenergic stimulation in man using atenolol and propranolol.

The respective contributions of beta-adrenoceptor subtypes to the hemodynamic, humoral and metabolic consequences of adrenergic stimulation during graded exercise in man were investigated using nonselective beta-adrenoceptor blockade with propranolol and beta 1-adrenoceptor blockade with atenolol. Doses of these agents that produced comparable suppression of beta 1 response as measured by antagonism of cardioacceleration during exercise were selected. Six healthy, nonsmoking males received these drugs in a placebo-controlled, Latin-square, randomized manner using a double-blind protocol. Both drugs produced comparable reductions of systolic blood pressure and elevation of diastolic blood pressure compared with placebo as exercise load increased. Propranolol produced higher peak epinephrine levels than atenolol or placebo (808 +/- 162, 640 +/- 190 and 584 +/- 153 pg/ml, respectively, p = 0.03), but norepinephrine levels did not show significant differences. Plasma renin activity was similarly suppressed both at rest and during all grades of exercise by both drugs. Lactate levels during moderate exercise were significantly lower after propranolol than after either atenolol or placebo (p = 0.03), but were similar at heavy work loads. Plasma glucose values rose on placebo (from 96.5 +/- 2.1 to 97.7 +/- 2.7 mg/dl) and on atenolol (from 99.7 +/- 2.2 to 102.1 +/- 4.8 mg/dl), but fell on propranolol (from 96.4 +/- 1.9 mg/dl to 87.2 +/- 2.5 mg/dl, p less than 0.01). These results indicate that blockade of vascular smooth muscle beta 2 receptors does not substantially alter hemodynamics during intense short-term exercise. Stimulation of renin release and lipolysis are produced through beta 1-adrenoceptor mechanisms, whereas beta 2 adrenoceptors are important in the provision of carbohydrate as an energy substrate for exercising muscle.

Adult↗
PubMed1983

Effect of water rinsing on sodium content of selected foods.

The sodium content of water-rinsed canned green beans, tuna, and cottage cheese was analyzed. A 3-minute rinse of tuna and cottage cheese resulted in sodium reductions of 80% and 63%, respectively, with no significant effect on iron content. Calcium was reduced by approximately 50%. Although rinsing had a minimal effect on the sodium in canned beans, replacing the canning brine with water before heating lowered salt content by 33%. This study shows that the simple and economical methods of water rinsing of tuna and cottage cheese and of heating green beans in tap water markedly lowered salt content.

Food Analysis↗