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Biomedical subjects

R D Feld

Publications and source records attributed to R D Feld.

29 records · Page 2Linked to original sources
PubMed1981

Esterolytic method for determination of heparin in plasma.

This assay for heparin is based on the heparin-accelerated rate of alpha-thrombin III. The rate or product formation from the residual active thrombin is inversely proportional to plasma heparin content. The assay can be performed manually, but our results were obtained with a discrete analyzer, the ABA-100. The assay is insensitive to concentrations of antithrombin III in plasma. Precision studies gave CVs of less than 10%. This assay was compared to the Dade Protopath heparin assay and a correlation coefficient of 0.90 was obtained (n = 62). The correlation between activated partial thromboplastin times and heparin concentrations (r = 0.67) was calculated frm results on 78 plasma specimens from 10 patients.

Antithrombin III↗
PubMed1980

The presence of creatine kinase BB isoenzyme in patients with prostatic cancer.

Creatine kinase BB isoenzyme (CK-BB) was detected in abnormal amounts in serum samples from 11 of 46 patients with Stage D carcinoma of the prostate by electrophoresis. Thirteen of 46 Stage D patients had elevated acid phosphatase values and 10 of these 13 had elevated CK-BB. CK-BB elevations were less frequent in earlier stages of prostatic cancer; Stage C: 0 of 35, Stage B: 1 of 26, Stage A: 0 of 3 and none in a group of 35 with BPH, prostatitis and bladder cancer. Results of CK-BB by a specific radioimmunoassay correlated well with those obtained by electrophoresis in most cases. Several patients were followed over time and data on CK-BB is presented for this interval. The origin of the CK-BB is still unclear. The BB isoenzyme predominates in prostatic tissue and CK-BB is the fetal form of the enzyme in human muscle and myocardium. The increase in serum CK-BB may be related to increased release of the isoenzyme, either from the prostate itself or from a metastatic lesion, or may represent a release of the fetal form of the enzyme from dedifferentiated tumor tissue.

Acid Phosphatase↗
PubMed1980

Enzymic inhibition assay for methotrexate with a discrete analyzer, the ABA-100.

We adapted an inhibition assay for methotrexate, involving dihydrofolate reductase from bovine liver, for use with a discrete analyzer (the ABA-100). The analyzer was used both for dilution and a 5-min pre-incubation of the sample with NADPH--enzyme reagent, and for the assay itself. The standard curve was linear between 10 and 120 microgram/L. Without pre-incubation the standard curve was nonlinear. The presence of albumin in the NADPH--enzyme reagent enhanced both enzyme activity and stability. Within-run precision (CV) was 2.0% (n = 24), run-to-run precision 7.1% (n = 49). Results obtained on patients' samples (29 sera, 15 urines, 18 cerebrospinal fluids) by the present method and a radioimmunoassay method did not differ statistically (p greater than 0.05) when the paired data were analyzed by use of the sign test and Wilcoxon's ranked sign test.

Albumins↗
PubMed1978

Effects of bilirubin on detection of hydrogen peroxide by use of peroxidase.

Bilitubin interferes with the quantitation of hydrogen peroxide in reagent systems in which peroxidase is used. Difference spectra suggest that this interference is a combination of chemical and spectral effects. The data presented are most consistent with the following interpretation: (a) bilirubin destroys part of the reactive intermediate formed in the peroxidase reaction and thus decreases the amount of chromophore formed and (b) the spectra for bilirubin and the chromaphore overlap, which also affects the results. The relevance of these results to reagent design and laboratory quality control are discussed.

Bilirubin↗
PubMed1978

Comparison of dewpoint and freezing point osmometry.

Osmolality was measured on 32 clear serum samples and on 23 urines, with dewpoint and with freezing point osmometers. The observed regression equation was dewpoint = 0.96 freezing point +7.6, with a correlation mean for 32 clear sera analyzed by both methods was not significantly different. However, when 14 lipemic sera were analyzed, the dewpoint measurements were higher: X dewpoint = 291.6; X freezing point = 284.1. The between-run standard deviation observed for a normal serum pool yielded a coefficient of variation of 1.04 with the freezing point and 2.38 with the dewpoint instrument. Results indicate that the dewpoint device should be used with caution for lipemic serum samples.

Blood Chemical Analysis↗
PubMed1977

Presence of creatine kinase BB isoenzyme in some patients with prostatic carcinoma.

We have observed creatine kinase isoenzyme BB in the sera of nine of 19 patients with Stage D carcinoma of the prostate. Its presence does not seem to correlate with acid phosphatase activity in serum or the presence of bone metastases as indicated by increased alkaline phosphatase activity in serum. Only three of the nine patients with BB isoenzyme activity detectable in their serum had abnormal values for total creatine kinase activity, but all had abnormal values for alkaline and acid phosphatase activity. All 10 patients with no BB isoenzyme detectable had abnormal acid phosphatase values; however, only seven had increased alkaline phosphatase values and only one had increased creatine kinase activity.

Creatine Kinase↗
PubMed1976

Kinetic determination of serum lipase activity with the Abbott ABA-100.

A turbidimetric procedure for lipase has been adapted for use on the Abbott Bichromatic Analyzer (ABA-100). The method is rapid and results compared well with those by the more traditional method of Cherry and Crandall [Am. J. Physiol. 100, 266 (1932)]. Advantages of this method include shorter incubation time (2 min), smaller sample size (50 mul), neglible interference from bilirubin, and greater dynamic range (to eightfold normal).

Amylases↗