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Biomedical subjects

N P Kubasik

Publications and source records attributed to N P Kubasik.

At least 19 recordsLinked to original sources
PubMed1985

The measurement of fractionated bilirubin by Ektachem film slides. Method validation and comparison of conjugated bilirubin measurements with direct bilirubin in obstructive and hepatocellular jaundice.

The authors evaluated the Kodak Ektachem Slides for total, "direct," conjugated, unconjugated, and albumin-bound ("delta") bilirubin. For various concentrations of control material, the precision (CV) within- and between-day ranged from 1.7 to 2.4% (2.8-6.6%) for total bilirubin, 0.8-4.2% (1.6-11.5%) for unconjugated bilirubin, and 1.6-9.5% (2.6-20.7%) for conjugated bilirubin. The Ektachem total and "direct" bilirubin assays demonstrated excellent correlation with the Jendrassik and Grof procedure; a 30% difference was observed, however, between absolute numbers with the two direct bilirubin methods. We found the measurement of true conjugated bilirubin by the Kodak Method to be superior to the measurement of "direct" bilirubin in following the response to treatment of various hepatic disorders manifested by extrahepatic and intrahepatic biliary obstruction.

Bilirubin↗
PubMed1984

Multilayered film analysis: evaluation of ammonia and creatinine slides.

We evaluated the Kodak Ektachem multilayer ammonia and creatinine slides. For various concentrations of control material the precision (CV) within- and (between-day) ranged from 0.8 to 7.8% (4.4-9.0%) for ammonia, and 1.9-25.1% (3.6-13.9%) for creatinine. A number of commercial control fluids were unacceptable choices due to the presence of elevated endogenous ammonia levels. For both analytes, analytical recovery was in the range of 100 to 108%. Comparison with the Jaffe reaction demonstrated good correlation for creatinine, and linearity was judged acceptable for both analytes. For ammonia, serum values were nearly double those of paired plasma samples. Plasma and serum samples, therefore, cannot be used interchangeably. No serum versus plasma differences were observed for creatinine.

Ammonia↗
PubMed1984

Evaluation of a direct solid-phase radioimmunoassay for progesterone, useful for monitoring luteal function.

We have evaluated a commercially available, direct, solid-phase radioimmunoassay kit for progesterone determination in serum or plasma. The assay is precise, within-run precision (CV) in the clinically significant ranges being 2.5 to 5.2%, between-run 5.5 to 5.8%. Mean analytical recovery of different concentrations of progesterone added to serum was 99.7% (range 95.3 to 102.7%). Fourteen closely related steroids showed no cross reactivity. The minimum detection limit was 0.5 microgram/L. Luteal-phase progesterone concentrations in serum were increased (greater than 3 micrograms/L) in 19 normal ovulatory menstrual cycles and decreased (less than 1.5 micrograms/L) in two nonovulatory cycles. We found this direct assay for progesterone to be analytically and clinically sound, and useful for assessing luteal-phase function.

Corpus Luteum↗
PubMed1983

Multilayer film analysis: evaluation of ion-selective electrolyte slides.

We evaluated the Kodak Ektachem multilayer ion-selective electrolyte slides. For various types and concentrations of control material the precision (CV) within- and between-day ranged from 0.5 to 1.3% (1.7-2.1%) for sodium, 1.2 to 2.2% (2.7-2.9%) for potassium, 2.9 to 4.6% (5.9-6.7%) for carbon dioxide, and 0.7 to 1.6% (1.3-1.4%) for chloride. For all these analytes, analytical recovery was about 100%, except in the supra-physiological ranges, for which carbon dioxide recovery was about 110-120%. Either serum or heparin-treated plasma can be used, interchangeably, for analysis; use of serum treated with lithium iodoacetate is unacceptable. Comparisons with results by continuous-flow procedures demonstrated good correlation for sodium, potassium, and chloride; carbon dioxide comparisons indicate an Ektachem calibrator change may be required. Abnormally low protein concentrations or lipemia had no observed effects on results for electrolytes. Abnormally high protein concentrations affect sodium results slightly (approximately 5 mmol/L).

Autoanalysis↗
PubMed1983

Free thyroxin by radioimmunoassay: evaluation of a new direct method involving a radiolabeled thyroxin analog.

We present here the first performance evaluation of a new direct method for free thyroxin (T4) in serum by radioimmunoassay, with use of coated tubes and a radiolabeled T4 analog (Diagnostic Products Corp.). The assay is precise and robust: within-run imprecision (CV), 3.1-6.6%; between-run imprecision, 4.0-7.9%; no demonstrable variation between technologists irrespective of experience with the method. No outliers were observed when we compared the free T4 results with serum total T4. Reference values are reported for a total of 1243 euthyroid subjects; there was no significant age effect on serum free T4 in women 26 to 72 years old. The biological variation was about +/- 35% of the mean (2 SD). Free T4 results are the same for serum and plasma. The assay performs well in hypothyroidism and hyperthyroidism, and distinguishes individuals with thyroid disease from normal individuals. Free T4 values in women taking oral contraceptives are normal. Depressed results were often observed in acute nonthyroidal illness and continuing pregnancy. These results were directly comparable with those of another commercial direct radiolabeled-T4 analog kit for free T4.

Adult↗
PubMed1982

Effect of duration and temperature of storage on serum analyte stability: examination of 14 selected radioimmunoassay procedures.

We determined appropriate temperatures for sample storage and the resulting stability of 14 analytes commonly radioimmunoassayed in the clinical laboratory. Serum specimens to be tested for concentrations of cholylglycine, cortisol, digoxin, ferritin, follitropin, immunoglobulin E, lutropin, prolactin, thyroxin (also blood-spot thyroxin), triiodothyronine, and triiodothyronine uptake could be stored for up to two weeks at room temperature, refrigerated, or frozen without any loss of analyte activity. Specimens for insulin testing require freezing or refrigeration, and specimens for gastrin testing should be stored at -70 degrees C for optimal results.

Blood Chemical Analysis↗
PubMed1980

Commercially-supplied binders for plasma cobalamin (vitamin B12), analysis--"purified" intrinsic factor, "cobinamide"-blocked R-protein binder, and non-purified intrinsic factor-R-protein binder--compared to microbiological assay.

Recent evidence (Kolhouse et al., N. Engl. J. Med. 299: 785-792, 1978) demonstrates that commercial cobalamin (Vitamin B12) radioassay kits contain nonspecific R-protein binding agents that can give falsely normal results in patients who are actually cobalamin deficient. We tested three kits: with "purified" intrinsic factor as the binder, with intrinsic factor and the nonspecific R-protein sites blocked with "cobinamide," and non-purified intrinsic factor-R-protein binder. Results with use of the first two compared well with those by a microbiological assay (Lactobacillus leichmannii) and are in harmony with clinical impressions.

Biological Assay↗
PubMed1980

The multilayered film analyzer: glucose in serum, plasma, cerebrospinal fluid, and urine; and urea nitrogen in serum and plasma.

Some basic laboratory performance criteria were studied for the Eastman Kodak glucose and urea nitrogen analyzer. Serum, plasma, urine, and cerebrospinal fluid were tested. Precision, both "within-day" and "between-day," for both analytes was less than 2.2% (CV). Both analytes demonstrated linearity, with about 100% recovery of added substrates. Comparisons with continuous-flow procedures demonstrated good correlation. A variety of sera and plasmas can be used for glucose analysis; oxalate--fluoride-treated plasma is unacceptable for use in analysis for urea nitrogen. We saw no effects on glucose or urea nitrogen analysis from hemolysis, lipemia, icterus, some common drugs, ammonia, or abnormally high protein concentrations. Minimum amounts detectable were: glucose (serum) 104 mg/L; glucose (cerebrospinal fluid) 100 mg/L; and urea nitrogen (serum) 21 mg/L. Calibration procedures are discussed for protein-based and aqueous samples.

Autoanalysis↗
PubMed1979

Evaluation of a new commercial radioassay kit for aldosterone using an iodinated tracer.

We have evaluated a new non-chromatographic commercial radioimmunoassay kit for serum, plasma, and urine aldosterone levels which employs 125 iodine as the tracer. Within-run and run-to-run precision data show coefficients of variation of 3 to 6% and 8 to 16%, respectively. Recovery of aldosterone added to serum and urine at several levels range from 92 to 109%. Antibody specificity was tested with six structurally related steroids at grossly elevated concentrations and no crossreactivity was observed. Serum or plasma can be used interchangeably in the assay, and normal levels correspond to generally accepted values.

Aldosterone↗