PubMed Health⌕ Search

Biomedical subjects

Z L Bandi

Publications and source records attributed to Z L Bandi.

16 recordsLinked to original sources
PubMed1989

An algorithm for testing and reporting serum choriogonadotropin at clinically significant decision levels with use of "pregnancy test" reagents.

We present an algorithm for monitoring the concentration of human choriogonadotropin (hCG) in serum at various clinical decision levels with use of fast, simple, and cost-effective qualitative pregnancy test reagents for hCG in serum. Based on correlation between laboratory data and clinical observations described in the literature, the following concentrations of hCG in serum can be considered as clinically significant decision levels: 5 int. units/L to exclude or "rule out" the presence of increased hCG; 25 int. units/L for "confirming pregnancy" or confirming the presence of increased hCG from sources other than the trophoblast; and 6500 and 82 500 int. units/L to enhance the sonographic diagnoses of ectopic pregnancies and molar pregnancies, respectively. We used Tandem Icon II (Hybritech) pregnancy test reagents and evaluated the reagents for possible "false-positive" findings at the 25 int. units/L limit of hCG detectability by analyzing 100 post-menopausal and more than 4000 premenopausal serum specimens. The performance of the reagents was validated also at 5 int. units/L and at limits of hCG detectability greater than 25 int. units/L.

Algorithms↗
PubMed1987

Enzyme-linked immunosorbent urine pregnancy tests. Clinical specificity studies.

The performance of six recently introduced highly sensitive enzyme-linked immunosorbent (ELISA) urine pregnancy test reagent kits was evaluated for false positive results using 100 male and 100 postmenopausal female urine specimens and the findings were compared with those of a qualitative radioimmunoassay (RIA) procedure. Based on the findings, the most suitable pregnancy test reagent kit was then selected for doing routine pregnancy testing of urine samples of premenopausal patients. The less sensitive PregnaSTICK ELISA method and Concept RIA procedure did not give any positive results. Positive results for postmenopausal female and male urine samples were obtained as follows: Testpack, 2 and 0 (greater than 50 mIU/mL [IU/L]); Icon, 2 and 0 (greater than 50 mIU/mL [IU/L]); Quest, 4 and 2 (greater than 50 mIU/mL [IU/L]); Nimbus, 17 and 4 (greater than 25 mIU/mL [IU/L]); and Sensi-Chrome, 33 and 19 (greater than 50 mIU/mL [IU/L]), respectively. The medical records of the patients whose urine samples gave positive results were examined for information that would have explained the positive results, but no clear-cut reasons were found. Comparison of the routine urinalysis findings showed that there was a correlation between the mucus content of female (but not of male) urine samples and the incidence of false positive human chorionic gonadotropin results. During 12 months of routine use of the Icon reagents for pregnancy testing of premenopausal urine samples, the University of Texas Medical Branch staff has not reported any suspected false positive findings to the authors.

Chorionic Gonadotropin↗
PubMed1987

Highly sensitive qualitative methods for serum choriogonadotropin (hCG): clinical specificity studies.

We screened six highly sensitive kits, designed for serum pregnancy tests, for false-positive results. The two best were then evaluated more extensively. The "BETA-hCG MAIA-clone" (I) and the "TANDEM ICON" (II) kits gave only negative results for 100 sera from men at 5, 10, and 25 int. units/L (1st IRP). Of 100 serum specimens from post-menopausal women three and 10 were hCG positive by the II and the I reagents, respectively, but only at the 5 int. units (1st IRP) of hCG per liter level of sensitivity. At 10 and 25 int. units/L, all specimens were negative by both tests. The manufacturers of these kits recommend pregnancy testing only at the 25 int. units/L level of analytical sensitivity. By quantitative methods, hCG concentrations in the II positive samples ranged from 6 to 20 int. units/L (1st IRP) and lutropin concentrations were between 130 to greater than 150 int. units/L. The medical records of the corresponding patients did not support the presence of trophoblast or any other hCG-secreting tissues. During 15 months of routine use of the II reagents at an analytical sensitivity of 25 int. units/L (1st IRP) hCG for pregnancy testing (greater than 4000 serum specimens from pre-menopausal women), the staff has not reported to us any suspected false-positive findings.

Adult↗
PubMed1985

Adsorption and reversed-phase high-performance liquid chromatography of p-nitrobenzyl esters of monohydroxy fatty acids.

To enhance the UV detectability of hydroxy fatty acids, p-nitrobenzyl (PNB) esters of twenty-two different monohydroxy fatty acids of various chain-lengths (C16-C22) and differing positional isomers were formed using O-(p-nitrobenzyl)-N,N-(diisopropyl)-isourea (PNBDI) as alkylating agent. Reversed-phase and adsorption high-performance liquid chromatography (HPLC) of the twenty-two monohydroxy fatty acid PNB esters were studied. The PNB group did not dominate the chromatographic properties of monohydroxy fatty acids and it did not interfere with the HPLC separation of positional isomers. PNBDI was, however, found to be less than ideal for formation of PNB derivatives of monohydroxy fatty acids because UV absorbing contaminants of PNBDI interfered with the HPLC analyses.

Chromatography, High Pressure Liquid↗
PubMed1985

Immunochemical methods for measurement of transferrin in serum: effects of analytical errors and inappropriate reference intervals on diagnostic utility.

We estimated analytical errors of the Calbiochem, Kallestad, Hyland, Meloy, Helena, and Beckman immunochemical methods for serum transferrin. Intermethod biases were determined by analysis of the "Reference Preparation for Serum Proteins" of the College of American Pathologists and by analysis of 106 patients' serum samples. We judged the acceptability of errors by comparing confidence limits for total errors with 1/4 of the normal reference intervals. The transferrin status of each patient's sample was interpreted by comparing the result of each method with the normal reference interval claimed by the corresponding manufacturer. We found that the combined effects of medically unacceptable analytical errors and inappropriate normal intervals caused results of the tested methods not to be interchangeable. The Calbiochem method identified 61 serum samples (57%) as having abnormally high transferrin concentrations. In contrast, for the same specimen, with the Meloy method we found abnormally high transferrin concentrations for only two samples (1.8%).

Analysis of Variance↗
PubMed1982

Improved nonradioactive method for routine clinical analysis for long- and medium-chain stool lipids.

We describe a simple, practical method for routine clinical determination of long- and medium-chain stool lipids. Stool lipids were extracted into a hot mixture of benzene/ethanol/water (12/59/29, by vol), saponified in 30 min without formation of ethyl esters, and titrated in a clear, one-phase medium to a sharp color change. CVs for the titration were 2, 1, and 1% for 0.05, 0.25, and 0.5 mmol of fatty acids, respectively. Interference of stool short-chain acids other than fatty acids was not statistically significant. The precision of sampling of stool homogenate was improved by analysis of two aliquots, one from the top and one from the bottom of the suspension. This method of sampling is a practical alternative to the unpleasant homogenization with a blender or to the addition of large quantities of bile salts. The accuracy of the method may be increased, in special cases, by removing potential interferants.

Esters↗
PubMed1982

Evaluation of determination of glucose in urine with some commercially available dipsticks and tablets.

Four commercial products for urine glucose determination were evaluated and compared with a quantitative hexokinase procedure. We examined precision, sensitivity, and analytical recovery of glucose from glucose-supplemented urine samples and comparison of methods, using patients' samples. Only "Chemstrip uG" (Bio-Dynamics Inc.) could differentiate between 0.3 g/L (upper limit of normal) and 0.6 g/L urine glucose concentrations. "Tes-Tape" (Lilly) and "Diastix" (Ames) gave positive readings at 0.3 g/L; "Clinitest" (Ames) detected glucose only over 1 g/L. Analytical recovery of glucose was best, for all four products, between 1 and 2.5 g/L; Chemstrip uG was the most nearly accurate among the four. Between 5 and 20 g/L glucose concentrations, Tes-Tape, Diastix, and Clinitest tended to give falsely low results; the use of Chemstrip uG resulted in overestimates of concentration at 20 g of glucose per liter. Only Chemistrip uG and Clinitest (two-drop method) had linear ranges extending to 50 g/L; Chemstrip uG had better precision and accuracy at this concentration. Of the four products, Chemstrip uG had the lowest within-technologist and technologist-to-technologist random analytical errors. In method comparison on patients' samples, Chemstrip uG was significantly stronger in its association with the quantitative hexokinase method than was Diastix, Clinitest, or Tes-Tape.

Colorimetry↗
PubMed1981

Estimation, prevention, and quality control of carbon dioxide loss during aerobic sample processing.

We find that 2 to 6 mmol of carbon dioxide per liter (mean: 4.1 mmol/L) is lost during routine laboratory processing of patients' serum samples after centrifugation. Additional CO2 may be lost if evacuated blood-collection tubes are not filled completely during phlebotomy. More than 2 mmol of CO2 per liter is lost from samples stored in tightly stoppered tubes for 120 min if the tubes are less than half full. In extreme cases, 8 mmol of CO2 per liter may be lost from samples exposed to room air in open cups of automated micro-sample instruments. Clinically significant CO2 loss (greater than 2 mmol/L) before analysis is not detected by many laboratories because the generally accepted quality-control programs monitor only the very last step of the analytical process. A valid CO2 quality-control program should include samples with high as well as the generally used low pCO2 values. Alkalinization of serum and plasma samples with tert-butylamine prevents CO2 loss. Optimum tert-butylamine concentration, pH, and pCO2 were about 14 to 16 mmol/L, 9.0 to 9.3, and 0.4 to 1.5 mmHg (about 50 to 200 Pa).

Autoanalysis↗
PubMed1981

Extended clinical trial and evaluation of glucose determination with the Eastman Kodak Ektachem GLU/BUN Analyzer.

We followed the "abbreviated precision protocol" of the National Committee for Clinical Laboratory Standards for the evaluation of precision, accuracy, and carryover in analyses for glucose with the "Ektachem." We analyzed 760 clinical samples by this technique, by the FDA Proposed Class Standard glucose reference method, and with the Beckman System I GLU/BUN Analyzer. Precision and accuracy were estimated for 500, 1000, 1200, 1500, and 3000 mg/L glucose concentrations in 100, 30, or 20 microL of serum or plasma. Potential interference of 19 compounds was evaluated. Random error (1.965 X SD) was 22, 30, 34, 40, and 88 mg/L. Systematic error was 8, 1.5, -2, -5, and -27 mg/L. Total analytical error was 30, 32, 36, 46, and 110 mg/L for analysis of 100 microL of serum at the above-stated glucose concentrations. The greatest interference (-39 mg/L) in the glucose (at 1200 mg/L) determination was caused by L-ascorbate (40 mg/L). Glucose concentrations as determined with the Ektachem were found to be linearly related to the expected concentration up to at least 5660 mg/L. Carryover was not statistically significant.

Blood Chemical Analysis↗
PubMed1981

Extended clinical trial and evaluation of urea nitrogen determination with the Ektachem GLU/BUN analyzer.

We followed the "abbreviated precision protocol" of the National Committee for Clinical Laboratory Standards for the evaluation of precision, accuracy, and carryover in analysis for urea nitrogen with the multilayer film analysis system ("Ektachem"). We analyzed 456 clinical samples with this instrument, by the manual urease/glucose dehydrogenase method, and with the Beckman System I GLU/BUN Analyzer. Precision and accuracy were estimated for 50, 220, 270, and 500 mg/L urea nitrogen concentrations in 100, 30, or 20 microL of serum. Potential interference of 15 compounds was evaluated. Random error (defined as 1.965 X SD) was 7, 10, 12, and 18 mg/L. Systematic error was 3, 4, 5, and 15 mg/L. Total analytical error was 11, 14, 17, and 34 mg/L for analysis of 100 microL of serum at the above-stated urea nitrogen concentrations. The greatest interference (6 mg/L) was caused by ethanol (300 mg/L) and by hemoglobin (500 mg/L) in the urea nitrogen (at 260 mg/L) determination. Urea nitrogen concentration, as determined with the Ektachem was linearly related to the expected concentration, at least up to 1187 mg/L. Carryover was not statistically significant.

Autoanalysis↗
PubMed1978

Substrate specificity of enzymes catalyzing the biosynthesis of ionic alkoxylipids from alcohols.

An equimolar mixture of homologous saturated alcohols (13:0, 15:0, 17:0, 19:0) and an equimolar mixture of vinylogous alcohols (19:0, 19:1, 19:2) were fed to two groups of rats. All of the odd-numbered alcohols were incorporated into the ionic alkoxylipids of the rats' small intestine. Pronounced quantitative differences in the distribution of the various odd-numbered alkyl and alk-1-enyl moieties of choline phosphoglycerides and ethanolamine phosphoglycerides gave evidence to differences in the specificity of the enzyme system catalyzing the biosynthesis of alkoxylipids from long-chain alcohols.

Alcohols↗