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P H Lolekha

Publications and source records attributed to P H Lolekha.

15 recordsLinked to original sources
PubMed2001

Deproteinization of serum: another best approach to eliminate all forms of bilirubin interference on serum creatinine by the kinetic Jaffe reaction.

The negative interference of conjugated, unconjugated, and delta bilirubin on patient serum creatinine determined by the kinetic Jaffe reaction is the unresolved problem. We compared bilirubin interference on thirty patients' serum creatinine obtained from four analyzers, with and without deprotenization before the Jaffe reaction, to the Vitros dry enzymatic method. We found significant negative interference from bilirubin on serum creatinine in all samples directly applied to four wet chemical methods, except the one incorporated with serum blank rate. The negative interferences linearly related to bilirubin concentration. However, bilirubin did not interfere on serum creatinine obtained from all wet chemical methods incorporated with deproteinization process before the reaction. We conclude that deproteinized serum before the reaction is the best approach to eliminate all forms of bilirubin interference on serum creatinine determined by the kinetic Jaffe reaction.

Autoanalysis↗
PubMed2001

Reference ranges of electrolyte and anion gap on the Beckman E4A, Beckman Synchron CX5, Nova CRT, and Nova Stat Profile Ultra.

The widespread use of ion-selective electrode causes the reference range of the anion gap (AG) to be lowered from 8-16 to 3-11 mmol/l. The use of the outdated reference range (8-16 mmol/l) leads to the misinterpretation of the value of the anion gap. To interpret the anion gap accurately, one must use an analyzer-specific reference range. This study established the reference ranges of the electrolyte and anion gap in four ion-selective electrode analyzers. We collected clotted and lithium-heparinized blood from 124 healthy volunteers. We determined the electrolyte in the Beckman E4A (serum), Beckman Synchron CX5 (serum), and Nova CRT (serum and plasma). The anion gap was calculated from the formula: [Na(+)-(Cl(-)+HCO3(-))]. Blood sodium, potassium and bicarbonate were determined using the Nova Stat Profile Ultra. We used the plasma chloride from the Nova CRT to calculate the value of the anion gap in the Nova Stat Profile Ultra. We established the reference ranges using the non-parametric percentile estimation method. Accuracy and precision of the electrolyte performances obtained from all analyzers were acceptable. Reference values of serum and plasma sodium, potassium, and chloride were similar in all analyzers. The value of blood sodium obtained from the Nova Stat Profile Ultra was slightly higher than the values for the serum and plasma sodium obtained from the other analyzers. The bicarbonate ranges obtained from the Nova analyzers were higher than the values obtained from the Beckman analyzers. For the anion gap, the reference ranges in this study were low but similar to other studies (3-11 mmol/l) using ion-selective electrode. However, our reference ranges were lower than the previous reference ranges obtained from the continuous-flow analyzer (8-16 or 9-18 mmol/l) incorporated with flame photometry and colorimetry techniques.

Anions↗
PubMed2001

Update on value of the anion gap in clinical diagnosis and laboratory evaluation.

Anion gap (AG) is a calculated value commonly used in clinical practice. It approximates the difference between the concentration of unmeasured anions (UA) and unmeasured cations (UC) in serum. At present, the reference range of anion gap has been lowered from 8-16 to 3-11 mmol/l because of the changes in technique for measuring electrolyte. However, clinicians and textbooks still refer and use the old reference value of 8-16 mmol/l. This may lead to misinterpretation of the value of anion gap. Our study updated the value of anion gap in clinical diagnosis and laboratory evaluation. Criteria for using anion gap were also suggested. We analyzed serum electrolyte using the Beckman Synchron CX5. The anion gap was calculated from the formula: [Na(+)-(Cl(-)+HCO(3)(-))]. We estimated the reference range using the non-parametric percentile estimation method. The reference range of anion gap obtained from 124 healthy volunteers was 5-12 mmol/l, which was low and confirmed the reports from other studies (3-11 mmol/l) using ion-selective electrode. From the retrospective study on the 6868 sets of serum electrolyte among hospitalized patients, we found the incidences of normal, increased, and decreased anion gaps were 59.5%, 37.6%, and 2.9%, respectively. The mean and central 90% range of increased anion gap were 16 and 13-20 mmol/l, which was lower than those reported in previous study (25 and 19-28 mmol/l). Anion gap exceeding 24 mmol/l was rare. The mean and central 90% range of decreased anion gap were 3 and 2-4 mmol/l, which were lower than those reported in previous study (6 and 3-8 mmol/l). The value of less than 2 mmol/l was rare. The most common causes of increased anion gap (hypertensive disease, chronic renal failure, malignant neoplasms, diabetes mellitus and heart diseases) and decreased anion gap (liver cirrhosis and nephrotic syndrome) in this study were similar to those in previous studies. We found two cases of IgG multiple myeloma with anion gap of 2 mmol/l. In conclusion, clinicians and laboratorians can use the anion gap as clue in quality control. They can check the incidences of increased and decreased anion gap. If one finds high incidence of increased anion gap (>24 mmol/l) or decreased anion gap (<2 mmol/l), one should check the quality control of electrolyte and whether the patients were hypoalbuminemia or hyperglobulinemia. An anion gap exceeding 24 mmol/l will suggest the presence of metabolic acidosis. It is very rare to find anion gap with the negative sign.

Anions↗
PubMed1996

Optimization studies of components in enzymatic cholesterol reagents containing cholesterol oxidase from Nocardia erythropolis, Streptomyces sp, or Pseudomonas fluorescens.

Although enzymatic methods for serum cholesterol determination are widely used in clinical laboratories, little is known about the optimization of each component in enzymatic reagents. We investigated the optimal components in the reagents containing cholesterol oxidase isolated from Nocardia erythropolis, Streptomyces sp, or Pseudomonas fluorescens. The optimal components in the reagents are: cholesterol oxidase 250 (Nocardia erythropolis), 250 (Streptomyces sp), or 300 (Pseudomonas fluorescens) U/L, cholesterol esterase 200 U/L, peroxidase 10,000 U/L, sodium cholate 3 mmol/L, 4-aminoantipyrine 0.5 mmol/L, phenol 20 mmol/L, Triton X-100 2 mL/L, and phosphate buffer, pH 7.0. Lower reaction sensitivity and lower cholesterol linearity, < 18.1 mmol/L (700 mg/dL), could be obtained by using lower components than those suggested above. Pseudomonas fluorescens were an improper source for cholesterol oxidase; either Nocardia erythropolis or Streptomyces was suitable cholesterol oxidase. We prefer using Streptomyces sp cholesterol oxidase because of its economical cost and longest reagent stability. Sodium cholate must be included in the enzymatic reagent to prevent turbidity. However, sodium cholate of > 5 mmol/ L will suppress the reaction resulting in low cholesterol linearity.

Ampyrone↗
PubMed1994

Comparison of techniques for minimizing interference of bilirubin on serum creatinine determined by the kinetic Jaffé reaction.

This study compared the effect of sodium dodecyl-sulfate, potassium ferricyanide, and preincubation technique to continuous-flow analysis and prior deproteinization to correct the negative interference of bilirubin on serum creatinine found by the kinetic Jaffé reaction. Bilirubin increased to 684 mumol/L did not interfere with serum creatinine measured by the methods incorporated with dialysis or deproteinization. Trichloroacetic acid was the best protein precipitant. The reagent incorporated with sodium dodecyl sulfate was more appropriate to minimize bilirubin interference than reagent containing potassium ferricyanide. An increase in potassium ferricyanide concentration resulted in false positive creatinine values. Incorporation of both SDS and potassium ferricyanide in the reagent did not help in minimizing the bilirubin interference over use of each chemical alone. The 10 minutes of preincubation of the sample with alkaline buffer incorporating with either SDS or potassium ferricyanide before starting the Jaffé reaction was the appropriate way to overcome unconjugated bilirubin interference at a level of 342.0 mumol/L. However, the technique did not work uniformly with icteric patient sera containing conjugated, unconjugated, and delta bilirubin. This is a challenging problem that remains to be solved by the clinical chemist.

Bilirubin↗
PubMed1992

User-defined serum aspartate and alanine aminotransferase, cholesterol, triglycerides, urea, and uric acid for the Beckman synchron CX 4/5 using Ames Sera-Pak reagents.

Beckman aspartate aminotransferase (AST), alanine aminotransferase (ALT), cholesterol, triglycerides, urea, and uric acid Liquid Reagents for Synchron CX 4/5 (48, 48, 25, 60, 26, and 30 cents US/test, respectively) are expensive. We have established our own methods for serum AST, ALT, cholesterol, triglycerides, urea, and uric acid (6, 6, 5, 12, 13, and 6 cents US/test, respectively) using Ames Sera-Pak reagents. Linearity of our AST, ALT, cholesterol, triglycerides, urea, and uric acid methods were either similar to or higher than the Beckman methods. The within run and day-to-day run precisions were acceptable. Recovery of our AST, ALT, cholesterol, triglycerides, urea, and uric acid were excellent. Our results for AST, ALT, cholesterol, triglycerides, urea, and uric acid correlated well with the Beckman results. Bilirubin (340.8 mumol/L) did not significantly interfere on our AST, ALT, cholesterol, triglycerides, and urea, while its concentrations of 165.8 mumol/L started giving negative interference on uric acid. Turbidity (2+) did not interfere significantly on our AST and ALT but started giving positive interference on cholesterol, triglycerides, urea, and uric acid. Hemolysis (2+) gave positive interference on our cholesterol, triglycerides, urea, and uric acid. Stability of Ames Sera-Pak working reagents was at least 30 days for AST, ALT, urea, and uric acid and 40 days for cholesterol and triglycerides.

Alanine Transaminase↗
PubMed1992

Streptomyces: a superior source for cholesterol oxidase used in serum cholesterol assay.

The present study compared three cholesterol oxidase sources (Nocardia, Streptomyces, and Pseudomonas sps.) for serum cholesterol assay. We found cholesterol oxidase isolated from Streptomyces was superior than those isolated from Nocardia and Pseudomonas sps. Performances of the reagent contained Streptomyces cholesterol oxidase was excellent and comparable to the performances obtained from reagent contained Nocardia cholesterol oxidase. Moreover, the reagent containing Streptomyces cholesterol oxidase had the lowest cost and had the longest shelf-life ($U.S. 0.17/mL, 10 weeks) compared to the reagent contained Nocardia ($U.S. 0.50/mL, 8 weeks) or Pseudomonas ($U.S. 0.20/mL, 6 weeks) cholesterol oxidase.

Cholesterol↗
PubMed1987

Use of malate dehydrogenase immobilized on the dialyzer groove of the Autoanalyzer II for serum aspartate aminotransferase determination.

Malate dehydrogenase (EC 1.1.1.37) was immobilized on the lower groove of the dialyzer plate used for serum aspartate aminotransferase determination in the AutoAnalyzer II system. Immobilization was effected by covalently attaching malate dehydrogenase to the inner surface of the groove which was previously activated by treatment with glutaraldehyde at room temperature. The immobilized malate dehydrogenase catalyzed the reaction between oxaloacetate and NADH to form NAD in the coupled reaction originally proposed by Karmen. Results of the present method correlated well with those obtained by the Technicon SMA II system in which malate dehydrogenase is in solution (n = 99; r = 0.99; t = 0.30). The activity of immobilized malate dehydrogenase on the dialyzer groove was sufficient to measure serum aspartate aminotransferase for at least one month with continuous use. The stability of immobilized malate dehydrogenase was also dependent on the number of samples determined. The dialyzer plate is a reusable solid matrix for malate dehydrogenase immobilization. The expense of the present method is only half the cost of the method in which malate dehydrogenase is in solution.

Adolescent↗
PubMed1983

Value of the anion gap in clinical diagnosis and laboratory evaluation.

We report the incidence of normal (50.4%), increased (46.7%), and decreased (2.9%) anion gap among hospitalized patients in a retrospective study. The mean and range of increased anion gaps were 25 and 19-28 mmol/L. Values exceeding 30 mmol/L were uncommon and may indicate either acidosis or laboratory error. The most common causes of the increased anion gap among patients were chronic renal failure, congestive heart failure, malignant neoplasm, and diabetes mellitus. Increased anion gap in this study may be due to excess acids along with decreases in sodium, chloride, and carbon dioxide. The mean and range of decreased anion gap were 6 and 3-8 mmol/L. Anion-gap values less than 3 mmol/L were uncommon (one of 500 cases), and a high incidence of such values may indicate laboratory error. Nephrotic syndrome, liver cirrhosis, intestinal obstruction, and severe hemorrhage were the common disorders associated with decreased anion gap, which resulted from hypoalbuminemia and hyponatremia. Although most patients with decreased anion gap had hypoalbuminemia, hypoalbuminemic patients did not necessarily have decreased anion gap.

Adolescent↗
PubMed1980

Evaluation of serum creatinine measurement by the direct acidification method for errors contributed by non-creatinine chromogens.

Serum creatinine determination by the direct acidification method was found to be non-specific. Chromogens other than creatinine could react with alkaline picrate and their developed color was also destroyed by acid. Only elevated levels of bilirubin and acetoacetate caused a significant interfering effect. The degree of this interference depended on: (1) the amount of the interfering substance; (2) the reaction time allowed for color development; and (3) the final acidity for decolorization.

Acetoacetates↗
PubMed1980

Improved continuous-flow analysis for serum bilirubin.

A simple and improved method of continuous-flow analysis for total and direct bilirubin in serum is described. Advantages of the method are: small serum and reagent volumes; the use of less concentrated caffeine solution in the accelerator; the substitution of distilled water for hydrochloric acid in the direct bilirubin channel; and the close agreement of results obtained by the present and Jendrassik-Grof reference method when purified bilirubin is used as the calibrating standard.

Animals↗
PubMed1978

New continuous-flow analysis for simultaneous determination of creatinine and uric acid in 200 microliters of serum without use of a dialyzer.

We present a new method for direct continuous-flow (AutoAnalyzer II) measurement of serum creatinine and uric acid. The manifold is simple, inexpensive, and can be constructed in the laboratory. Only 200 microliters of serum is needed; analysis rate is 60 samples per hour. The incorporation of sodium dodecyl sulfate and the simultaneous provision of blank subtraction make it possible to omit the dialysis step. Our method does not require the linearizer, since instrument response and concentration of creatinine and uric acid are linearly related to 200 and 120 mg/liter, respectively. The percentages of steady state, interaction, and recovery are acceptable, Precision is excellent and the results obtained from the new method correlate well with those obtained by the comparison methods. Interferences are few and, when encountered, are generally smaller than in the modified Technicon method. Marked hemolysis interferes only with the uric acid assay; marked turbidity has no effect on results for creatinine. Icteric serum with total bilirubin of 50 and 100 mg/liter interferes significantly with results for creatinine and uric acid, respectively, by the new method.

Autoanalysis↗