Chemical and physicomechanical aspects of biocompatible orthopaedic polymer (BOP) in bone surgery.

The properties of biocompatible orthopaedic polymer developed as an alternative to the metallic materials used in reconstructive bone surgery are discussed. Experiments were conducted to enhance the mechanical characteristics of the polymer by incorporation of various fibres. The result was a super biocompatible orthopaedic polymer which could be a valuable alternative to intra-medullary long bone metallic rods, whilst normal biocompatible orthopaedic polymer is currently used for bone filling and reconstructive surgery.

The value of serum CK-MB and myoglobin measurements for assessing perioperative myocardial infarction after cardiac surgery.

In 41 patients who underwent coronary bypass surgery, creatine kinase (CK)-MB mass concentration was repeatedly measured in serum during and after the intervention using a new two-site immunoenzymetric assay (IEMA). Serum CK-MB activity was determined with the use of four different techniques: immunoinhibition, immunoinhibition-immunoprecipitation, column chromatography and electrophoresis. Myoglobin (Mb) was also measured in each specimen by radioimmunoassay. In the 33 patients who followed a completely uneventful postoperative course, the cumulated CK-MB release was, on the average, 12.2-fold less than after acute myocardial infarction. The CK-MB peak concentrations using the IEMA were 33 +/- 3 micrograms/l (X +/- SEM) and occurred 6.4 +/- 0.5 h after the intervention was started; CK-MB levels had decreased to 2.9 +/- 0.4 micrograms/l at the end of the first postoperative day. The evolution of the CK-MB concentration was parallel to that of the enzyme activity. The serum Mb maximum concentrations (518 +/- 39 micrograms/l) were reached after 3.3 +/- 0.1 h. The other eight patients developed perioperative myocardial infarction (PMI); in this group, the cumulated CK-MB release was higher, and the serum CK-MB postoperative curves were of three different types. The patients with delayed CK-MB peaks (type I pattern) or sustained elevations (type III) of this isoenzyme also showed increased serum Mb levels at the end of the first postoperative day. The PMI patients with early (10 h) CK-MB elevations (type II) did not demonstrate abnormal serum Mb levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum creatine kinase isoenzyme MB concentration after endomyocardial biopsy.

Serum total creatine kinase (CK), CK-MB and myoglobin (Mb) were serially determined in 17 patients who underwent endomyocardial biopsy. Mean total CK levels increased from 36 +/- 27 U/l 30 min before biopsy to a maximum of 112 +/- 77 U/l 8 h following the procedure (p less than 0.05). Similarly, Mb concentrations rose from 57 +/- 55 micrograms/l to 119 +/- 57 micrograms/l 30 min after biopsy (p less than 0.05). Normalization of total CK and Mb levels occurred within 16 and 8 h, respectively. A new immunoenzymetric assay (IEMA) was used to measure the mass concentration of the CK-MB molecule. The initial CK-MB levels were 0.2 +/- 0.4 microgram/l; a small but significant elevation was recorded as early as 2 h after biopsy (1.6 +/- 1.5 micrograms/l, p less than 0.05). CK-MB returned to initial concentration 16 h after the beginning of the procedure. Comparison with the maximum CK-MB levels recorded in 16 myocardial infarction patients (258 +/- 172 micrograms/l, range 90-680 micrograms/l) indicated that the modest increase of CK-MB level detected after biopsy probably reflects a limited endomyocardium lesion at the sampling site, excluding any significant myocardial damage. Total CK and Mb, which showed more pronounced elevations than CK-MB, are likely to originate from other sources than the myocardium.

[Use of monoclonal antibodies for the immunoenzyme determination of creatine kinase-isoenzyme MB]. / Utilisation des anticorps monoclonaux pour la détermination immunoenzymologique de la créatine kinase-isoenzyme MB.

An enzyme immunoassay using monoclonal antibodies for creatine kinase-MB in human serum is described. The specificity and the linearity have been studied. The coefficient of within assay ranges from 6% to 22.5% according to the concentrations. The coefficient of between-assay ranges from 8% to 16.6%. Compared to electrophoresis, the results obtained with the enzyme immunoassay are a better sign of the physical state of the patients.

Differentiating muscle damage from myocardial injury by means of the serum creatine kinase (CK) isoenzyme MB mass measurement/total CK activity ratio.

We immunoenzymometrically measured creatine kinase (CK) isoenzyme MB in extracts of myocardium and in homogenates of five different skeletal muscles. CK-MB concentrations in the former averaged 80.9 micrograms/g wet tissue; in the skeletal muscles it varied widely, being (e.g.) 25-fold greater in diaphragm than in psoas. CK-MB in skeletal muscles ranged from 0.9 to 44 ng/U of total CK; the mean for myocardium was 202 ng/U. In sera from 10 trauma and 36 burn patients without myocardial involvement, maximum ratios for CK-MB mass/total CK activity averaged 7 (SEM 1) ng/U and 18 (SEM 6) ng/U, respectively. Except for an infant (220 ng/U), the highest ratio we found for serum after muscular damage was 38 ng/U. In contrast, the mean maximum ratio determined in 23 cases of acute myocardial infarction exceeded 200 ng/U. Among seven determinations performed 8 to 32 h after onset of symptoms, each infarct patient demonstrated at least one ratio greater than or equal to 110 ng/U. Ratios observed after infarct were unrelated to treatment received during the acute phase. We propose a CK-MB/total CK ratio of 80 ng/U as the cutoff value for differentiating myocardial necrosis from muscular injury.

Semi-quantitative estimation of serum myoglobin by a rapid latex agglutination method: an emergency screening test for acute myocardial infarction.

The present study reports the evaluation of a new latex agglutination test for serum myoglobin (SMb). The time of agglutination of the latex particles coated with antibodies to myoglobin was measured in 172 serum specimens with known concentration of myoglobin quantitated by a radioimmunoassay (RIA), collected from myocardial infarction (MI) patients, subjects suffering from various diseases, and normal controls. Myoglobin levels in the samples were found to decrease exponentially with time of agglutination. Agglutination occurring within 1 min (result coded as + + + +) corresponded to 761 +/- 366 micrograms/l of myoglobin; between 1 and 2 min (+ + +), to 285 +/- 101 micrograms/l; between 2 and 3 min (+ +), to 85 +/- 47 micrograms/l; between 3 and 4 min (+), to 51 +/- 38 micrograms/l; and after more than 4 min (-), to 31 +/- 16 micrograms/l. Blood samples were serially drawn from 24 MI patients with short hospitalization delays; the rapid agglutination which was obtained in the specimens taken upon admission (20 results coded as + + + + and four as + + +) actually corresponded to markedly increased SMb levels. In contrast, serum creatine kinase (CK) activities were still less than 150 U/l in four patients (16.6%); CK-MB was less than 5 U/l in five cases (20.8%). Positive agglutinations for SMb were also obtained 4 and 8 h following admission in all subjects, confirming that the latex test is an early and very sensitive indicator for MI.(ABSTRACT TRUNCATED AT 250 WORDS)

On the interpretation of serial laboratory measurements in acute myocardial infarction.

Serial laboratory determinations are now routinely performed on patients admitted to intensive-care units. Adequate interpretation of such cumulative information for clinical decision-making purposes is a challenging problem. We describe a statistical method for predicting--sequentially as the data become available--the patient's outcome, death or survival. Thus, the method goes beyond previously reported techniques that base such prediction on only a single multivariate observation. The method has been applied to daily measurements of serum urea and lactate dehydrogenase, performed during one week on patients hospitalized in the coronary-care unit with acute myocardial infarction. Two baseline variables were also included in the dynamic risk index so derived: the age of the patient and the number of previous myocardial infarctions recorded on admission. We also discuss the problems of selecting the most-predictive laboratory tests and of determining for each test the amount of past data needed to achieve satisfactory prediction. We distinguish between global evaluation of the dynamic risk index obtained (in terms of specificity and sensitivity) and individual interpretation (in terms of posterior/prior probability ratio) of a given risk score for a particular patient. The approach described may contribute to more effective use of results of repeated laboratory tests on critically ill patients.

Does lactate dehydrogenase isoenzyme-5 contribute to the predictive power of total lactate dehydrogenase in myocardial infarction?

In 385 patients with acute myocardial infarction, lactate dehydrogenase (LD; EC 1.1.1.27) isoenzymes were determined electrophoretically 24, 48, and 72 h after admission. At those times, LD-1/LD-2 ratios exceeding 1 were recorded in 78.9, 88.8, and 92.2% of the cases, respectively. LD-1 ranged from 181 to 2674 U/L, or 21.9 to 66.1% of the total activity. On the first day of hospitalization, 27.3% of the patients demonstrated abnormal LD-5 (greater than 6% of total LD); this finding dropped to 20.5% and 17.4% in the two following days. Early increases in LD-5 were most frequently observed in patients associating inferior infarcts with posterior or lateral extension and having a previous history of myocardial infarction. On day 1, LD-5 was significantly increased in early deceased patients as compared to long-term survivors (9.7% vs 4.9% of total LD, p less than 0.01). LD-5 definitely contributes to the prognostic efficiency of total LD in acute myocardial infarction, but does not replace it as a risk predictor. This study confirms the superiority of total LD over the isoenzyme measurements to achieve short-term prognostication.

Effect of the haptoglobin phenotype on the size of a myocardial infarct.

We investigated the relation between haptoglobin (Hp) phenotypes and serum levels of various biochemical markers after myocardial infarction in 496 patients. In 122 subjects selected on the basis of short delays until hospitalization, patients with Hp 2-2 had higher cumulated creatine kinase activity than patients with Hp 1-1, or Hp 2-1 (P less than 0.05), as well as higher myoglobin concentrations (P less than 0.02) 12 to 28 hours after admission. Comparison of serum enzyme activities in the remaining 374 patients confirmed that Hp 2-2 patients had significantly higher total creatine kinase, creatine kinase isoenzyme MB fraction, aspartate aminotransferase, and lactate dehydrogenase peak levels. Complications of left ventricular failure were more frequent in these patients (P = 0.05). Our results suggest that Hp 2-2 patients have more severe myocardial infarctions than Hp 1-1 and Hp 2-1 patients, However, no difference in the distribution of haptoglobin phenotype was found between patients who had a myocardial infarction and healthy subjects, indicating that Hp 2-2 does not predispose to the occurrence of infarction.

Critical evaluation of serum uric acid levels in acute myocardial infarction.

Serial measurements of serum uric acid were performed on patients suffering from acute myocardial infarction. Nearly 80 percent of the cases demonstrated a fall in uric acid concentrations during the first two days of hospitalization and a subsequent return to initial levels within six to eight days. There was a relationship between the decrease in uric acid levels and the serum lactate dehydrogenase activity. No evidence could be found that male patients were hyperuricemic as compared to control subjects. However, female patients between 40 and 60 years of age demonstrated significantly higher uric acid levels than healthy women of corresponding ages, even after adjustment for diuretic use.

The prognostic significance of serum alpha 1-acid glycoprotein changes in acute myocardial infarction.

Serum alpha 1-acid glycoprotein and haptoglobin concentrations were evaluated in 151 patients with acute myocardial infarction (MI) during the first ten days of hospitalization. Maximum glycoprotein concentrations were found to be related to myoglobin and enzyme peak levels. Glycoprotein levels recorded upon patients' admission did not vary for acute phase survivors and early deaths (15 patients), but the latter demonstrated significantly higher alpha 1-acid glycoprotein levels (p less than 0.05) on day 1. The maximum glycoprotein concentrations were, however, reached too long after the onset of acute MI to be of interest for short-term prognosis. Comparison of the evolution of the two glycoproteins investigated in late deaths (10 patients) and in 6-month survivors indicated increased alpha 1-acid glycoprotein levels in non-survivors, with a maximum discrimination occurring on day 8 (p less than 0.001). Haptoglobin was not significantly different in the two groups and even demonstrated lower concentrations from day 4 to day 10 in non-survivors. The decrease of haptoglobin levels in patients with hepatic dysfunction could explain the divergent results given by the serum concentrations of the two glycoproteins to predict mortality. We show in this study that alpha 1-acid glycoprotein measured at the end of hospitalization can give relevant prognostic information for the 6-month period following acute MI.

The protection of creatine kinase MM sub-bands by EDTA during storage.

We examined the effect of a 5 mmol/l concentration of EDTA on the stabilization of the five serum creatine kinase MM isoenzymes, resolved by thin-layer isoelectric focusing. In patient sera, total CK and CK-MB activities were stable during storage of the samples for two months at 4 degrees C even in the absence of EDTA. However, EDTA stabilized the labile MM and MM1 sub-bands, which are the first to appear in the blood after the release from the damaged tissue and its addition to blood samples intended for determining the MM sub-band pattern is recommended. The stabilizing effect of EDTA was emphasized at higher temperatures. EDTA protected the CK-MM pattern in myocardium extracts made in normal serum and incubated at 37 degrees C during 40 h, but was unnecessary when myocardium was homogenized in heat-inactivated serum. It is thought that EDTA could act by inhibiting a heat-labile component of human serum.

Further heterogeneity demonstrated for serum creatine kinase isoenzyme MM.

Serum creatine kinase (EC 2.1.3.2) isoenzyme MM was resolved by isoelectric focusing into a five-band pattern, a pattern that gradually changed after the onset of myocardial infarction. Similar changes were also demonstrated in patients undergoing coronary-bypass surgery. The evolution of two CK-MB sub-bands was studied in both cases. We found that three electrophoretic bands (CK-MM, pI 7.10; MM1, pI 6.88; MB1, pI 5.61) were predominant in patterns for sera collected during the early phase of myocardial infarction, but rapidly disappeared during the following hours, whereas bands of increased electrophoretic mobility (MM2, pI 6.70; MM3, pI 6.45; MM4, pI 6.25; MB2, pI 5.34) gradually increased. MM3 was always the major band at the end of the observation period in acute myocardial infarction (mean, 61.4% of total creatine kinase activity 36 h after the peak value for total creatine kinase in serum). The CK-MM bands were also present in the serum of patients without heart disease. Changes in the electrophoretic pattern were induced by a thermolabile factor in normal human serum, which transformed the muscular or myocardial MM and MM1 bands after their release into the blood stream.