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Biomedical subjects

J A Lott

Publications and source records attributed to J A Lott.

At least 91 records · Page 5Linked to original sources
PubMed1983

Immunoglobulin-complexed aspartate aminotransferase.

We report two cases of unexplained, isolated, persistently increased aspartate aminotransferase activity in serum. In the first patient, this lasted for 10 years and prompted multiple hospitalizations and medical/surgical consultations. For patient two, the abnormal enzyme activity resulted in hospitalization for further evaluation of possible heart disease. In spite of extensive investigation to determine the possible reason for the abnormality, no clear clinical cause was ever discovered in either patient. Electrophoretic and immunologic evidence indicates that the enzyme was complexed to IgG in the serum of both individuals. Recognition that this complex is probably benign may obviate other patients having to undergo unnecessary hospitalization, anxiety, and expense.

Aspartate Aminotransferases↗
PubMed1983

Synthetic materials for platelet quality control.

At present, the quality control of platelet counting by semi-automated and automated methods does not meet ideal standards. Controls prepared from human or animal platelets have limited stability, and some synthetic platelet controls that are available do not have the size distribution of fresh platelets. The platelet control materials described here are wholly synthetic; however, their particle size distribution is like that of normal human platelets, and the dispersing medium has the viscosity and surface tension of plasma. Two types of products are described. The first type are dilutions of the synthetic platelets which are handled like 3000-fold dilutions of platelet-rich plasma and are intended for direct use on instruments like the Coulter ZBI. The two dilution levels gave counts of about 50,000 and 200,000/microL on the Coulter ZBI and were found to be stable for at least 30 days at - 20C, 4C, and 37C, and at least eight months at 25C. The second type of product is handled like whole blood and is intended for direct use on instruments like the Coulter Model S-Plus. This product gave counts of about 200,000/microL and was found to be stable for at least 120 days at - 20C, 4C, 25C, and 37C. Freezing at - 20C produced some aggregates that dispersed after thawing and standing for several days prior to testing.

Autoanalysis↗
PubMed1982

Further improvement of the enzyme-linked antiglobulin test (ELAT) for erythrocyte antibodies.

The enzyme-linked antiglobulin test (ELAT) was found to be nine times more sensitive than the direct antiglobulin test (DAT) in detecting erythrocytes sensitized by IgG antibody in vitro. The release of hemoglobin and other interfering substances from the erythrocytes gave falsely high absorbance values which were corrected by the use of a hemolysis bland with each test. ELAT results showed good precision. With the use of the hemolysis blank, the ELAT should prove to be a useful tool for hospital blood blanks in the detection of weakly reactive allo- and autoantibodies.

Antibodies↗
PubMed1982

Interlaboratory survey of enzyme analyses IV. Human versus porcine tissue as source of creatine kinase for survey serum.

A special enzyme survey was carried out in 185 laboratories on specimens fortified with either porcine heart or human skeletal muscle creatine kinase (CK). All analytical systems were examined to see if they gave different results for porcine and human CK as compared with analysis of the same specimens on the duPont ACA. Analytical differences were found. However, these differences were small, and, with some exceptions, do not prevent interconversion of units based solely on specimens fortified with porcine CK. Both types of specimens serve equally well in estimating bias and variability of CK analyses. Based on the results for the human material, many laboratories appear to use inappropriate reference ranges for CK.

Animals↗
PubMed1982

Transformation of creatine kinase-BB isoenzyme in vitro: effect of carboxylic acids, thiols, pH, cations, and chelators.

Creatine kinase isoenzyme BB from rat brain was incubated with serum, dialyzed serum, or plasma, with added carboxylic acids, thiols, buffers, or cations. It was found to be very unstable at 37 degrees C under all these conditions, being transformed to CK-BB', a form that migrates like CK-MB on agarose electrophoretic plates. This transformation is enhanced at alkaline pH and, especially, by Zn2+. CK-BB' is quite stable, and probably results from binding of cations to CK-BB, because the transformation is prevented by EDTA and citrate.

Animals↗
PubMed1981

Interlaboratory survey of Enzyme Analyses iii. Does College of American Pathologists' survey serum mimic clinical specimens?

Participants in the last College of American Pathologists Enzyme Surveys in 1978 were asked that they provide results for lactate dehydrogenase (LD), alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and creatine kinase (CK), for the six interrelated Enzyme Survey serum specimens, and were also asked to provide results for the same enzymes from six healthy persons and from 50 patients. Extensive data analysis revealed that porcine LD and CK in the Survey serum had kinetic properties similar to the native enzymes in fresh human serum. On this basis, we were able to merge the normal data from laboratories using diverse methods and to establish a "universal" reference range for these two enzymes. Survey serum may serve as a bridge for the clinical comparison of very diverse methods for determining LD and CK, possibly for AST and ALT, but not for ALP.

Alanine Transaminase↗
PubMed1981

Intralaboratory survey of alkaline phosphatase methods.

Three sets of interrelated specimens containing alkaline phosphatase (ALP) were analyzed: CAP 1977 Enzyme Survey serum, human serum supplemental with calf intestinal ALP, and human serum with increased human liver ALP. Five quite distinct ALP methods were used. In addition, fresh serum from volunteer blood donors and serum from patients with increased serum ALP activities were examined by each of these five methods. Conversion factors for the five different methods based on results from calf-intestine-supplemented interrelated specimens could not be used to interconvert results for fresh human serum. However, the interrelated specimens with increased human liver ALP made interconversion of results for fresh human serum possible.

Alkaline Phosphatase↗
PubMed1980

Diagnosis of fetal death in utero with amniotic fluid creatine kinase.

There is a need for a widely available and accurate method of diagnosing fetal death in utero. The accepted standard technique for making this diagnosis is real-time ultrasonography, but this procedure is not available at all hospitals. However, almost every hospital laboratory has the capability of measuring creatine kinase in body fluids. One hundred eight pregnant women underwent real-time ultrasonography and analysis of amniotic fluid for creatine kinase. Ninety-one women with conditions that required amniocentesis during the second and third trimesters had a life fetus by ultrasonographic examination and a low level of amniotic fluid creatine kinase (0 to 3 sigma units per milliliter). Seventeen women with a dead fetus by ultrasonographic examination had an abnormally high level of amniotic fluid creatine kinase (5 to 9,800 sigma units per milliliter). The only erroneous diagnosis in this series involved a set of twins, one of whom was shown by real-time ultrasonography to be alive and the other dead. Both sacs contained abnormally high, although different, levels of creatine kinase. Analysis of creatine kinase in amniotic fluid is a reliable technique for diagnosing fetal death.

Amniotic Fluid↗
PubMed1980

Serum enzymes and isoenzymes in the diagnosis and differential diagnosis of myocardial ischemia and necrosis.

Diagnosis of injury to the myocardium is facilitated by information on the activities of creatine kinase (EC 2.7.3.2) MB isoenzyme (CK-MB) and lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 in serum, thee isoenzymes being present in higher activities in the myocardium than in other tissues or in normal serum. The temporal relationships of these isoenzymes, total creatine kinase, total lactate dehydrogenase, and aspartate aminotransferase (EC 2.6.1.1) are highly sensitive and specific for acute injury to the heart, particularly acute myocardial infarction. Chronic heart diseases, electric cardioversion for heart rhythm disturbances, coronary catheterization, and exercise usually do not produce increases of CK-MB, although abnormal aspartate aminotransferase, creatine kinase, lactate dehydrogenase, and lactate dehydrogenase isoenzyme 1 activities are seen in some individuals. Many other causes of increased activities of these enzymes and isoenzymes in serum are unrelated to injury to the heart. Because CK-MB is present in the skeletal muscle in low activities, substantial injury to skeletal muscle can increase CK-MB activities in the blood to abnormal values. Pulmonary embolism can mimic myocardial infarction in its clinical presentation. In patients with an accurately known time of onset of symptoms and serial enzyme analysis every 12 h during the first 48 h, acute myocardial infarction can be distinguished from pulmonary embolism by determinations of creatine kinase, CK-MB, aspartate aminotransferase, and lactate dehydrogenase isoenzyme 1 in serum.

Aspartate Aminotransferases↗
PubMed1980

Clinical evaluation of an immunoinhibition procedure for creatine kinase-MB.

We have clinically evaluated the Dade "Cardiozyme" immunoinhibition procedure for determination of creatine kinase isoenzyme MB (CK-MG) in 71 patients who were suspected of having had an acute myocardial infarction. Electrophoresis for CK-MB was also carried out. On the basis of diagnostic sensitivity and specificity for myocardial infarction, we found the Dade procedure for CK-MB to be somewhat inferior to electrophoresis. In 11 patients for whom the time of infarction was known, we observed normal CK-MB results for two of them by both immunoinhibition and electrophoresis during the first 24 h, but subsequently could detect abnormal CK-MB results by both methods. Thus in some patients such data are not helpful for making a diagnosis in the first 24 h. The Dade procedure is easy to perform, but lacks sensitivity in the region of low CK-MB activity, requires a very stable spectrophotometer, is imprecise, and produces negative numerical results in patients without myocardial infarction.

Adult↗
PubMed1980

Serum gastrins in Zollinger-Ellison syndrome: identification of localized disease.

We determined the relative concentrations of gastrin molecular species in serum samples from 21 patients with Zollinger-Ellison syndrome with localized gastrinoma (n = 11) or gastrinoma with hepatic metastases (n = 10). Gastrin molecular species were separated by gel-filtration chromatography and quantitated by radioimmunoassay with a gastrin antiserum produced in our laboratory. The percentage gastrin-17 of the total gastrin in the two groups differed significantly (nonparametric Wilcoxon rank test; p less than 0.01). Patients with the Zollinger-Ellison syndrome with apparently localized gastrinoma had a lower percentage of G- 17 (7.6%, SEM 1.6%) than did patients with gastrinoma with hepatic metastases (31.1%, SEM 6.1%). This procedure may be useful in the early classification of tumors in patients with Zollinger-Ellison syndrome.

Gastrins↗
PubMed1980

Apparent mitochondrial creatine kinase in the serum of a patient with metastatic cancer to the liver.

Creatine kinase (CK, EC 2.7.3.2) activity in the serum of a patient with metastatic carcinoma migrated as two distinct bands cathodal to the origin and to CK-3 on agarose gel electrophoresis. The more cathodal isoenzyme (CKm-2) is of high molecular mass, is precipitated by ammonium sulfate at 30% of saturation, and is not retarded by Sephadex G-100. Treatment with urea at a concentration of 6 mol/L caused CKm-2 to elute with proteins of lower molecular mass on a G-100 column and shifted the electrophoretic migration to a position just cathodal to the origin (CKm-1). Antibody to CK-1 and CK-2 did not affect the activity of either CKm-1 or CKm-2. Similarities between these cathodal bands of CK activity and mitochondrial CK suggest the mitochondrial origin of these isoenzymes. These cathodal CK isoenzymes reacted unpredictably with different commercial reagent systems for determination of CK activity in serum or in agarose gel.

Clinical Enzyme Tests↗
PubMed1978

Assessment of a rapid test on amniotic fluid for estimating fetal lung maturity.

We have measured the absorbance of centrifuged amniotic fluids at 650 nm. and found reasonably good correlation between the absorbance and the L/S ratio. In 87 fluids studied, an absorbance of greater than 0.100 predicted correctly an L/S ratio of 2 or more in 98 per cent of the cases. When the absorbance was less than 0.100, 70 per cent of the fluids had an L/S ratio of less than 2.

Amniotic Fluid↗