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J A Lott

Publications and source records attributed to J A Lott.

At least 37 records · Page 2Linked to original sources
PubMed1996

Isoforms of alkaline phosphatase determined by isoelectric focusing in patients with chronic liver disorders.

Fractionation of alkaline phosphatase isoenzymes and isoforms by isoelectric focusing is a simple procedure that resolves up to 17 fractions having alkaline phosphatase activity. The fractions are stable at 4 degrees C, and undergo only slight changes during repeated freeze-thaw cycles. Pretreatment with phospholipase-C or sialidase changes the isoelectric focusing patterns of alkaline phosphatase in serum; we recommend they not be used owing to the loss of information. We found that the alkaline phosphatase fractions provide diagnostic information in addition to that given by the common liver-function tests in patients with chronic liver diseases. Primary biliary cirrhosis and primary sclerosing cholangitis showed similar biochemical changes, but they are very different from alcoholic cirrhosis based on the common liver-function tests and the alkaline phosphatase isoform patterns obtained by isoelectric focusing. Analysis of the laboratory data using neural networks has some limited use in distinguishing chronic and chronic-active hepatitis of any cause. We have confirmed the tissue assignments made by Griffiths (Prog Clin Biochem 1989; 8:63-74) for the alkaline phosphatase fractions in liver as obtained by isoelectric focusing: Fractions 1a and 1b show a strong correlation with biliary diseases, and fractions 2, 3, and 4 show consistent increases in patients with primary disorders of hepatocytes; these fractions have good sensitivity for hepatocyte injury, but their specificity is limited. Fraction 10 may be a marker of activated T-lymphocytes; it was abnormal in most of our patients suggesting that it is a sensitive but non-specific test. Analysis of alkaline phosphatase by isoelectric focusing deserves further evaluation, because it may facilitate the diagnosis of certain chronic liver disorders and could be a supplement to the biopsy.

Alkaline Phosphatase↗
PubMed1996

Use of medians and "average of normals" of patients' data for assessment of long-term analytical stability.

Using results from patients, we studied several methods for long-term (years) monitoring of the analytical stability of various chemistry tests. For each test, we obtained on a bimonthly basis histograms of > or = 200 to approximately 2000 data points and determined the median, mean, and mean of those data points in the reference range ("average of normal" or AON). Examining approximately 4 years' data, we found that the medians and AON are extremely stable for most tests, and that all observed shifts in the medians or in the AON could be explained by expected or unexpected changes in the laboratory. The means and peak values of the Erlang (gamma) distribution were less useful, owing to shifts caused by extreme outliers, especially for enzymes in serum. We assumed that the underlying patient population and testing patterns were stable. We recommend the use of medians or the AON of patients' data under defined conditions for monitoring the long-term analytical stability of certain tests involving serum or whole blood.

Ammonia↗
PubMed1995

Evaluation of an automated urine chemistry reagent-strip analyzer.

We evaluated the Miles Inc., Clinitek Atlas Automated Urine Chemistry Analyzer for 11 tests: bilirubin, color, glucose, ketones, leukocyte esterase, nitrite, occult blood, pH, protein, specific gravity, and urobilinogen. The instrument uses a roll of reagent strips affixed to a clear plastic support; urine specimens are automatically pipetted onto these strips. The instrument measures the pads' color using reflectance colorimetry. Specific gravity is measured using a fiberoptic refractive index method. Four hospitals participated in the evaluation, and tests were performed only on fresh urine samples. We found the instrument easy to use; it has walk-away capability with up to 40-specimen loading capacity plus spaces for STATs, calibrators and controls. We found good comparability with chemical tests and other nonreagent strip procedures, as well as good agreement with the Miles Inc. Clinitek 200+ urine chemistry analyzer and visual reading of the Miles Inc. Multistix Reagent Strips. The Clinitek Atlas is rugged and reliable, and is suitable for a high-volume urinalysis laboratory.

Automation↗
PubMed1995

Time changes of creatine kinase and creatine kinase-MB isoenzyme versus discrimination values in the diagnosis of acute myocardial infarction: what is the optimal method for displaying the data?

We wanted to determine the optimal method for displaying data for the clinical evaluation of patients with possible acute myocardial infarction. Our primary question was, are the time changes (slopes) of the enzyme tests better predictors of disease than the discrimination values, i.e., the cut-off points? We studied 152 patients with and 114 without a diagnosis of acute myocardial infarction in their medical records. For patients with acute myocardial infarction, we found the most discriminating tests, in decreasing order of the area of the ROC curves, to be the creatine kinase-MB slope at 0 to 12 hours, the creatine kinase-MB slope at 12 to 24 hours, the creatine kinase-MB values between 12 and 24 hours, and the creatine kinase-MB values between 0 and 12 hours. Decreasing values of creatine kinase-MB in the first tests after admission were only slightly less discriminating than increasing ones. At 12 to 24 hours after admission, the total creatine kinase as a value or slope, or the "relative index" (a ratio of the creatine kinase-MB in microgram/l [times 100] to the total creatine kinase) as a value or slope were inferior to creatine kinase-MB presentations. From the data for 44 patients with acute myocardial infarction and a known time of onset of symptoms, we were able to estimate an approximate onset time in patients where this was not available.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Enzyme Tests↗
PubMed1994

Alkaline phosphatase isoforms in serum after liver allograft surgery.

Orthotopic liver transplantation (OLT) is now the only available treatment for end-stage liver disease; the major postoperative complications of OLT are rejection and infection. Fractionation of alkaline phosphatase (ALP) isoforms in serum by isoelectric focusing can be used to identify patients with complications. Reference ranges for liver-function tests (LFT) and liver ALP isoforms were established for post-OLT patients with stable postoperative courses and compared with those of patients with complications. We found canalicular, hepatocyte, and high-molecular-mass ALP to be statistically higher in nearly all patients with complications as compared with patients who had a stable postoperative course; these tests may identify patients requiring a liver biopsy. When used in conjunction with LFT and other clinical findings, ALP isoforms could aid in the monitoring of complications and treatment and in the adjustment of immunosuppressive therapy in stable OLT cases.

Adolescent↗
PubMed1993

Screening for proteinuria in patients with hypertension or diabetes mellitus.

BACKGROUND: Proteinuria is an early indication of renal disease. This study was conducted to evaluate the usefulness of dipstick urinalysis in patients with chronic diseases including hypertension and diabetes mellitus. METHODS: At a university family practice center, patients without urinary tract disorders underwent dipstick urinalysis. RESULTS: Of the 796 patients evaluated, increased proteinuria, possibly indicating early renal disease, was detected in 4% of healthy patients, 16% of patients with hypertension, 29% of patients with diabetes, and 53% of patients with both hypertension and diabetes. A higher incidence of proteinuria was found among African American patients with hypertension or diabetes or both than among white patients. CONCLUSIONS: Regular dipstick evaluation for proteinuria may be indicated in patients with hypertension or diabetes mellitus or both, particularly African American patients with these disorders.

Adolescent↗
PubMed1993

"Direct" and total bilirubin tests: contemporary problems.

In eight unique challenges mailed by The College of American Pathologists Comprehensive Chemistry Survey to participating laboratories within 3 years, results for direct-reacting bilirubin (DBIL) were highly variable among the 12 largest peer groups, and most of the results differed greatly from the values obtained by a referred method. Peer-group mean values for total bilirubin (TBIL) were in much better agreement with each other and with those obtained by the Reference Method for TBIL. From a review of the information on the assay of DBIL provided to us by the manufacturers, we conclude that among the major causes of the large variability and bias in DBIL assays are problems with calibration, lack of a serum blank measurement, inadequate concentrations of HCl in the reaction mixture, inappropriate use of bichromatic correction methods, and possibly the use of wetting agents or surfactants in the reagent. Within-group SDs were small and generally acceptable. The among-peer-group variability in DBIL values is attributable to bias, not imprecision. We recommend several simple changes that could improve the accuracy of DBIL determinations in clinical laboratories.

Bilirubin↗
PubMed1992

Estimation of reference ranges: how many subjects are needed?

We measured Na, K, Cl, glucose, hemoglobin, erythrocytes, and hematocrit in the serum or blood from approximately 800 male and 200 female second-year medical students in an effort to define the size of an acceptable reference population. Using the data from the men and Monte Carlo simulations of 10-400 samples, each carried out 5000 times, we found that for most of the above tests, approximately 200 people are required for stable lower (2.5%) and upper (97.5%) reference limits to be obtained. This agrees with the 198 subjects required by strictly statistical criteria to define the same limits with a 99% confidence level.

Adult↗
PubMed1991

Clinical chemistry.

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Chemistry, Clinical↗
PubMed1991

Lipase isoforms and amylase isoenzymes: assays and application in the diagnosis of acute pancreatitis.

Pancreatic juice and serum from patients with acute pancreatitis contain three enzymes that have lipolytic activity: L1 and L2, which are pancreatic isoenzymes or isoforms of lipase (EC 3.1.1.3), and L3, which is probably pancreatic carboxyl ester lipase, also known as cholesterol esterase (EC 3.1.1.13). These enzymes are readily separated electrophoretically on agarose and can be developed with an overlay of Kodak Ektachem lipase slide material. The latter acts as a dry-reagent developing substrate, with the enzymes producing blue bands in the slide material. We found L1 in about one-half of normal persons, L2 in none, and L3 in all. We assayed for amylase (EC 3.2.1.1), amylase isoenzymes, lipase, and lipase isoforms in the sera of 100 patients with suspected acute pancreatitis. L2 lipase has the greatest diagnostic efficiency for the diagnosis of pancreatitis, compared with total amylase, P3 amylase, and total lipase. Lipase and L2 could replace amylase, an inefficient test, for the diagnosis of patients with suspected acute pancreatitis. In patients receiving organ transplants, a serum amylase value of greater than 300 U/L or a lipase of greater than 1000 U/L discriminated well between patients with and without complications and (or) acute rejection.

Acute Disease↗