Plasma enzymes in diagnosis (clinical enzymology)

2013 ◽  
pp. 270-281
Author(s):  
Martin Andrew Crook
Keyword(s):  
Plasma Enzymes ◽  
Clinical Enzymology

Mechanism of Heparin Rebound

1979 ◽  
Author(s):  
I. Fabian ◽  
M. Aronson
Keyword(s):  
Clotting Time ◽  
Coagulation Time ◽  
Working Hypothesis ◽  
Plasma Enzymes

Heparin rebound is occasionally encountered following protamin sulfate administration for the neutralization of excess of heparin. in these situations the anticoagulatory properties of heparin are initially abolished, but within several hours the blood display again an increased clotting time. The purpose of this work was to try to reproduce the phenomenon under in vitro conditions, and to provide a working hypothesis for its explanation. Under the condition used the following parameters were obtained (according to the APTT method): clotting time of untreated plasma 50-55 seconds; with the addition of 4 units heparin/ml plasma>3 minutes; and with the addition of 50-100 μg of protamin to the heparinized plasma the clotting time reverts to 50-55 seconds. It was, however, found that incubation of heparin-protamin complex with the plasma at 37° for several hours, reduced the effectivity of the protamin, in other words, a longer coagulation time was observed. Subsequently, we found by electrophoretical methods that (heparin bound) protamin is proteolitically degraded upon incubation in plasma, the anticoagulatory properties of the heparin remaining intact. in summary, our results are compatible with the hypothesis that heparin rebound can be explained by the degradation of protamin by plasma enzymes and the release of this newly available heparin Into the circulation. The importance of this phenomenon in conjunction with other observations previously described by us are discussed.

Production and certification of secondary enzyme reference materials (ERMs). Part 1: Preparation of the sera and some of their properties.

1986 ◽  
Vol 32 (10) ◽  
pp. 1901-1905 ◽  
Author(s):  
J C Koedam ◽  
G M Steentjes ◽  
S Buitenhuis ◽  
E Schmidt ◽  
R Klauke
Keyword(s):  
Creatine Kinase ◽  
Lactate Dehydrogenase ◽  
Reference Material ◽  
Human Serum ◽  
Dehydrogenase Activity ◽  
Aspartate Aminotransferase ◽  
Alanine Aminotransferase ◽  
Glutamate Dehydrogenase Activity ◽  
The Stability ◽  
Clinical Enzymology

Abstract We produced three batches of a human-serum-based enzyme reference material (ERM) enriched with human aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2), creatine kinase (EC 2.7.3.2), and lactate dehydrogenase (EC 1.1.1.27). The added enzymes were not exhaustively purified; thus the final ERMs contained some enzymes as contaminants, of which only glutamate dehydrogenase activity might interfere. The stability during storage and after reconstitution was good. The commutability of the four enzymes in the three ERM batches was also good, except when German or Scandinavian methods for aminotransferases were involved. The temperature-conversion factors for the ERMs were equivalent to those for patients' sera. Reactivation after reconstitution was complete within 5 min and was independent of the temperature of the reconstitution fluid. We believe that these secondary ERMs will aid in the transfer of accuracy between well-defined reference methods and daily working methods so that clinical enzymology results will become more comparable from laboratory to laboratory.

Effect of exercise, hypoxia, and epinephrine on lysosomes and plasma enzymes

1975 ◽  
Vol 22 (2) ◽  
pp. 242-251 ◽  
Author(s):  
Daniel J. Loegering ◽  
Michael L. Bonin ◽  
James J. Smith
Keyword(s):  
Plasma Enzymes

Clinical enzymology

1978 ◽  
Vol 64 (1) ◽  
pp. 165-170
Author(s):  
M. Desmond Burke
Keyword(s):  
Clinical Enzymology

Clinical enzymology

1978 ◽  
Vol 64 (2) ◽  
pp. 149-156
Author(s):  
M. Desmond Burke
Keyword(s):  
Clinical Enzymology

scholarly journals Selenium-dependent glutathione peroxidase protein and activity: immunological investigations on cellular and plasma enzymes

Blood ◽  
1986 ◽  
Vol 68 (3) ◽  
pp. 640-645 ◽  
Author(s):  
K Takahashi ◽  
HJ Cohen
Keyword(s):  
Enzyme Activity ◽  
Glutathione Peroxidase ◽  
Protein Content ◽  
Polyclonal Antibodies ◽  
Plasma Enzyme ◽  
Plasma Enzymes ◽  
Erythrocyte Enzyme ◽  
Dependent Protein ◽  
Gshpx Activity ◽  
Almost All

Selenium-deficient humans and animals are known to be deficient in glutathione peroxidase (GSHPx) activity in their cells and plasma. To determine the relationship between enzyme activity and protein content, the enzyme was purified from human erythrocytes, and polyclonal antibodies were made against the purified protein in rabbits. These antibodies were found to be monospecific, noninhibitory, and capable of precipitating the enzymatic activity. All the GSHPx activity in erythrocytes and almost all the activity in neutrophils and platelets was precipitated by these antibodies. None of the plasma enzyme was precipitated by these antibodies, indicating that the plasma enzyme activity was attributable to a different selenium dependent protein moiety. Utilizing a radioimmunoassay, we were able to determine that there was a direct relationship between GSHPx activity and protein content in the erythrocytes of both normal and selenium-deficient individuals, and a similar relationship between control and selenium- deficient rat erythrocytes and liver cells. Thus, the ability to examine GSHPx as a protein resulted in two new observations concerning the selenium-dependent GSHPx. The first is that the plasma enzyme is antigenically distinct from the erythrocyte enzyme, and the second is that in the absence of selenium, there is a concomitant decrease in GSHPx protein.

scholarly journals A Validated HPLC-PDA-HRMS Method to Investigate the Biological Stability and Metabolism of Antiparasitic Triterpenic Esters

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7154
Author(s):  
Laura Schioppa ◽  
Fanta Fall ◽  
Sergio Ortiz ◽  
Jacques H. Poupaert ◽  
Joelle Quetin-Leclercq
Keyword(s):  
Medicinal Plants ◽  
Degradation Products ◽  
Biological Stability ◽  
Acidic Media ◽  
Microsomal Metabolism ◽  
Plasma Enzymes ◽  
Absorption Studies ◽  
H 30

Pentacyclic triterpenes (PTs) are commonly found in medicinal plants with well-known antiparasitic effects. Previous research on C-3 and C-27 triterpenic esters showed effective and selective in vitro antiparasitic activities and in vivo effectiveness by parenteral routes. The aim of this study was to determine triterpenic esters’ stability in different biological-like media and the main microsomal degradation products. An HPLC-PDA method was developed and validated to simultaneously analyze and quantify bioactive triterpenic esters in methanol (LOQ: 2.5 and 1.25–100 µg/mL) and plasma (LOQ: 5–125 µg/mL). Overall, both triterpenic esters showed a stable profile in aqueous and buffered solutions as well as in entire plasma, suggesting gaining access to the ester function is difficult for plasma enzymes. Conversely, after 1 h, 30% esters degradation in acidic media was observed with potential different hydrolysis mechanisms. C-3 (15 and 150 µM) and C-27 esters (150 µM) showed a relatively low hepatic microsomal metabolism (<23%) after 1 h, which was significantly higher in the lowest concentration of C-27 esters (15 µM) (>40% degradation). Metabolic HPLC-PDA-HRMS studies suggested hydrolysis, hydroxylation, dehydration, O-methylation, hydroxylation and/or the reduction of hydrolyzed derivatives, depending on the concentration and the position of the ester link. Further permeability and absorption studies are required to better define triterpenic esters pharmacokinetic and specific formulations designed to increase their oral bioavailability.

scholarly journals A rapid simple method for the assay of renin in rabbit plasma

1968 ◽  
Vol 108 (4) ◽  
pp. 679-685 ◽  
Author(s):  
J W Ryan ◽  
J. K. McKenzie ◽  
M. R. Lee
Keyword(s):  
Rabbit Plasma ◽  
Selective Inhibitors ◽  
Angiotensin I ◽  
Simple Method ◽  
Renin Substrate ◽  
First Order ◽  
Complete Inactivation ◽  
Plasma Enzymes ◽  
First Order Kinetics ◽  
Percentage Release

1. EDTA (10mm), 2,3-dimercaptopropan-1-ol (10mm) and chlorhexidine gluconate (0·005%, w/v) cause complete inactivation of plasma enzymes that degrade angiotensin I, but have no effect on the reaction of renin with its substrate. The reagents were termed the selective inhibitors. 2. Thus it is possible to measure renin in plasma by its ability to catalyse the release of angiotensin I. 3. Sterile plasma, treated with the selective inhibitors, is incubated with renin substrate (500–1000ng. of angiotensin content/ml.) at pH6 at 42° for 6hr. 4. Under these conditions the reaction obeys first-order kinetics. Renin activity is calculated in terms of the percentage release of the angiotensin content/hr. 5. As described, the assay is sufficiently sensitive to measure renin in the plasma of all normal rabbits. By extending the length of the incubation, much lower activities can be measured.

Sign in / Sign up

Export Citation Format

Share Document