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W Gerhardt

Publications and source records attributed to W Gerhardt.

At least 37 records · Page 2Linked to original sources
PubMed1986

SCE Nordic alpha-amylase study. II: Assessment of proposed calibration procedure. A report by the Scandinavian Committee on Enzymes (SCE).

Eighty-seven Nordic Hospital laboratories participated in a joint SCE-NORDKEM follow-up study of the long-term stability of the previously established calibration factors for a number of alpha-amylase routine methods based on six different substrates. Human control materials with 90% pancreatic, 90% salivary, and pure pancreatic alpha-amylases were measured by the participants. The data were plotted before and after calibration of each method using a human pancreatic calibrator with an assigned catalytic concentration of 390 U/l (Phadebas blue starch method, 37 degrees C). As in the previous study, carried out 9 months earlier, the pre-calibration values varied over a six-fold range. The post-calibration values of all methods except those based on a tetraose substrate showed an acceptable inter-laboratory comparability. As a temporary measure, SCE recommends that the Nordic laboratories calibrate the accepted routine methods by their individual calibration factor. Detailed suggestions for calibration procedures and a discussion of the principles of transferability will shortly be published by the SCE in this journal.

Calibration↗
PubMed1985

SCE Nordic alpha-amylase method selection and calibration study. A report by the Committee of Enzymes of the Scandinavian Society for Clinical Chemistry (SCE).

Seventy-six Nordic routine laboratories participated in a joint SCE-NORDKEM study comprising evaluation, selection, and temporary calibration of amylase methods. Human control materials with known fractions of salivary and pancreatic amylase were determined by seven routine amylase assays based on substrates with glucosyl (G) chain lengths G4, G5, G5-6, G7, G9, amylopectin and blue starch polymer (Phadebas). The data were plotted before and after calibration of each method using a human pancreatic calibrator with an assigned value of 390 U/l (37 degrees C, Phadebas). the study led to three conclusions: The analytical overestimation of salivary to pancreatic amylase ratio (S:P) increased with decreasing number of glucosyl units in the substrates. Relative to the S:P value of blue starch polymer (set at 1.00), for example, tetraose mean S:P value was 1.55. The hydrolysis rates relative to that with blue starch polymer decreased with the number of glucosyl units in the substrates. The precalibration values of all methods spread over an approximately six-fold range. Post-calibration values of all methods, except tetraose, showed an acceptable inter-laboratory comparability. The CV values for low, medium, and high controls were about 5.5, and 6% respectively. As a temporary solution to the current problem of diverse amylase assays, the SCE suggests calibration of the methods considered acceptable in this study. The long-term effects will be evaluated in a follow-up study within a year.

Calibration↗
PubMed1985

Specific immunoassay of alpha-amylase isoenzymes in human serum.

A monoclonal antibody (66C7) was prepared that specifically binds human salivary amylase (EC 3.2.1.1); it cross reacts with human pancreatic amylase by less than 1%. Two procedures are described for determination of isoamylases in human serum with this antibody: an enzyme immunoassay for determining amylase of salivary origin, and a routine method in which this amylase is immunoprecipitated and the remaining (pancreatic) amylase activity is assayed. Results by the two methods correlate well.

Antibodies, Monoclonal↗
PubMed1983

Multicentre investigation of myocardial protection with cold cardioplegia.

In order to analyze factors of importance for the efficiency of myocardial protection during open-heart surgery, a study was made of 144 patients undergoing isolated aortic valve replacement with various cardioplegic techniques. The cardioplegia was of Bretschneider type in 54 cases, St Thomas in 31 and Ringer-potassium type in 11 cases. Single or multi-dose blood cardioplegia was used in 11 cases and continuous blood cardioplegia in 30 cases. Local cardiac hypothermia was additionally employed in all patients. The efficiency of myocardial protection was assessed mainly from the incidence of postoperative conduction disturbances, myocardial enzyme release and need for inotropic support. All patients survived the operation. In 20% surgery was followed by transient or persistent disturbance of conduction, in 9% by abnormally increased CK-MB release and in 5% by requirement for inotropic support. Preoperative risk factors such as high age or severe left ventricular (LV) hypertrophy or dysfunction had little influence on the results. Patients in whom aortic stenosis (AS) was dominant in the complex with aortic insufficiency (AS + AI) showed 20-hour postoperative CK-MB enzyme activity twice as high as those with pure aortic insufficiency. The most important factors in myocardial protection were the duration of aortic occlusion and the myocardial temperature during cardioplegia. When the aortic occlusion lasted more than 80 min there was a 32% incidence of conduction disturbances and 20-hour CK-MB activity thrice as high as after shorter occlusion. Patients with mean myocardial temperature below 18 degrees C during cardioplegia invariably had low enzyme activities, which indicated good myocardial protection. The best overall results were obtained in patients operated on during hypothermia at 25-27 degrees C, with single or multi-dose blood cardioplegia and with efficient local cooling of the heart.

Adult↗
PubMed1983

Serum LD-1 activity in suspected acute myocardial infarction.

We have studied the diagnostic value of measuring lactate dehydrogenase (LD) isoenzyme 1 in serum of 331 cases of suspected acute myocardial infarction (AMI). At a discriminatory level of 200 U/L (Scandinavian Committee on Enzymes, recommended method for the determination of LD) LD 1 verified the diagnosis in 96% of the AMI cases and excluded it in 96% of the not-AMI cases when samples were drawn 24-72 h after onset of pain. The correlation between 24-h S-LD-1 and 16-h S-CK B activities was 0.94 in the AMI cases. We found that quantitation of serum LD-1 is diagnostically more reliable than the serum LD-1/LD ratio.

Acute Disease↗
PubMed1982

Plasma carboxypeptidase activity and intolerance to acetylsalicylic acid unimpaired CP-N activity in ASA-intolerant individuals.

Carboxypeptidase N (EC 3.4.17.3, arginine carboxypeptidase, kininase, anaphylatoxin inactivator) activity was determined in human sera with the method of Erdös by differential spectrometry at 254 nm and 37 degrees C, using hippuryl-L-argininic acid (HLAa) as a substrate. Day-to-day imprecision (CV) of the assay was 6.5%. The reference value, as determined in 15 healthy blood donors, was 3,082 +/- 432 IU/1. The mean value in a pool of sera from 12 healthy pregnant women, 4,500 +/- 294 IU/1, was higher in accordance with earlier findings by Erdös et al. Sera from 53 patients with chronic asthma or chronic urticaria, without known acetylsalicylic acid (ASA) intolerance, gave the mean value of 3,583 +/- 768 IU/1, and those from 17 patients with chronic asthma or chronic urticaria and ASA intolerance 3,379 +/- 575 IU/1. Thus, the carboxypeptidase-N activity in the blood of ASA-intolerant asthmatics and urticaria patients was unimpaired. A 16-year-old boy with asthma and without ASA intolerance showed an unusually low value of 2,056 IU/1.

Aspirin↗
PubMed1982

Creatine kinase and creatine kinase B-subunit activity in serum in cases of suspected myocardial infarction.

We evaluated a diagnostic strategy by studying 481 patients suspected of having had an acute myocardial infarction; the prevalence of infarction by independent criteria was 0.43. This strategy is based on the sequential application of: (a) clinical criteria; (b) total creatine kinase determinations in two serum samples drawn within 10 to 20 h of the onset of acute symptoms; and (c) creatine kinase B-subunit (S-CK B) determinations after immunoinhibition with antibodies to creatine kinase M-subunit in the reaction medium in all samples found to have increased total creatine kinase activity. Discrimination limits of 150 U/L total creatine kinase for women and 200 U/L for men gave a diagnostic sensitivity of 0.99. Activities less than these limits in samples identified 68% of the 274 non-infarct cases (posterior probability of a negative result of 0.99) within 20 h. Subsequent determination of S-CK B in 292 patients who were positive by the discrimination limits for total creatine kinase verified myocardial infarction in 99% of 207 cases for which S-CK B exceeded the discrimination limit of 12 U/L. The strategy excluded 98% of all non-infarct cases at a posterior probability of 0.99.

Alanine Transaminase↗
PubMed1982

[Chronic hemodialysis from the perspective of the dialysis team].

By means of a questionnaire the authors checked the views of dialysis teams on ethical and psycho-emotional questions, on on the adaptation of dialysis patients and on dialysis work itself. The results show that psycho-emotional considerations are of considerable importance in the contact with patients over long periods. The staff think about them but are often not able to arrive at a clear opinion. This indicates that psychological training of the staff is necessary in oder to facilitate and encourage the formation of clear points of view.

Adult↗