| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Articles |
1
Department of Medical Chemistry and Biochemistry, Division of Clinical Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria.
2
Department of Anatomy 3, University of Vienna, A-1010
Vienna, Austria.
3
Department of Pediatrics, University of Freiburg,
D-79106 Freiburg, Germany.
4
Department of Pediatrics, University of Innsbruck,
A-6020 Innsbruck, Austria.
5
Department of Internal Medicine, Division of Pneumology,
University of Freiburg, D-79106 Freiburg, Germany.
6
Department of Internal Medicine, Division of Cardiology,
University of Innsbruck, A-6020 Innsbruck, Austria.
a Address correspondence to this author at: Department of Medical Chemistry and Biochemistry, Division of Clinical Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria. Fax 43-512-507-2876; e-mail
Angelika.Lercher{at}uibk.ac.at.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Methods: Plasma from 14 patients (mean age, 7.5 years; range, 5.7–19.4 years) with DMD was investigated for creatine kinase (CK), the CK MB isoenzyme (CKMB), cTnT and cardiac troponin I (cTnI), and myoglobin. cTnT concentrations were measured by an ELISA (second-generation assay; Roche) using the ES 300 Analyzer. cTnI, myoglobin, and CKMB were measured by an ELISA using the ACCESS System (Beckman Diagnostics). Troponin isoform expression was studied by Western blot analysis in remnants of skeletal muscle biopsies of three patients with DMD and in an animal model of DMD (mdx mice; n = 6).
Results: There was no relation of cTnT and cTnI to clinical evidence for cardiac failure. cTnI concentrations remained below the upper reference limit in all patients. cTnT was increased (median, 0.11 µg/L; range, 0.06–0.16 µg/L) in 50% of patients. The only significant correlation was found for CK (median, 3938 U/L; range, 2763–5030 U/L) with age (median, 7.5 years; range, 6.8–10.9 years; r = -0.762; P = 0.042). Western blot analysis of human or mouse homogenized muscle specimens showed no evidence for cardiac TnT and cTnI expression, despite strong signals for skeletal muscle troponin isoforms.
Conclusions: We found no evidence for cTnT reexpression in human early-stage DMD and in mdx mouse skeletal muscle biopsies. Discrepancies of cTnT and cTnI in plasma samples of DMD patients were found, but neither cTnT nor cTnI plasma concentrations were related with other clinical evidence for cardiac involvement.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
In contrast, cTnI is uniquely located in the myocardium and has not been detected in tissues other than heart in any developmental stage (7)(8)(9)(10)(11). It is, therefore, highly specific for myocardial injury. TnI and TnT, together with TnC, form a complex that regulates the calcium-mediated interaction of actin and myosin in striated muscle. Both TnI and TnT are encoded by three different genes that are differentially expressed, namely, the slow- and fast-twitch skeletal and the cardiac TnI isoforms (12)(13). Moreover, in the human fetal heart, four cardiac TnT isoforms have been observed that are generated by combinatorial alternative splicing of two 5' exons (14)(15). cTnT isoforms have also been described in fetal human skeletal muscle, but during the prenatal period, they are down-regulated and skeletal isoforms of TnT are up-regulated. Thus, there are no cTnT isoforms detectable in healthy adult skeletal muscle (14).
Nevertheless, Baum et al. (16) found increased cTnT in human serum samples of patients with renal failure, and in a second study (4), they found increased cTnT in 8 of 33 patients with DMD without cardiac involvement. Similar results have been reported by Kobayashi et al. (17), who demonstrated increased cTnT concentrations in patients with polymyositis/dermatomyositis without cardiac failure.
Similarly to CKMB, fetal isoforms of cTnT may be reexpressed in regenerating skeletal muscle (17)(18). cTnT was found in regenerating adult rat skeletal muscle after injury or denervation (18), and cTnT protein expression was demonstrated in human skeletal muscle from patients with end-stage renal disease (19). Bodor et al. (20) found evidence of cTnT in biopsies from patients with DMD, polymyositis, or renal failure. However, the results of the above-mentioned studies were based on Western blot analysis and immunohistochemistry using antibodies that were not well characterized. For example, information or evaluation concerning the possible cross-reactivities with other troponin isoforms was lacking, and it remains unclear which epitopes of the TnT isoforms were recognized by these antibodies. Thus, there is still debate and residual uncertainty on possible reexpression of cTnT in skeletal muscle specimens of patients with chronic myopathies.
Because of controversial earlier studies, the purpose of this study was to provide novel experimental and additional clinical data regarding possible reexpression of cTnT in regenerating skeletal muscle. DMD was chosen as the prototype of myopathies with ongoing cycles of muscle fiber degeneration and regeneration. DMD is a degenerative X-chromosome-linked disease of skeletal muscle that usually causes death around the age of 20 via cardiomyopathy (CMP) or respiratory failure (21). This severe muscle-wasting disease results from mutations in the gene encoding for dystropin, a cytoskeletal protein under the sarcolemma of skeletal and cardiac muscle fibers. The absence of dystropin is proposed to lead to sarcolemmal instability and muscle cell necrosis (21)(22). We tested plasma and muscle biopsies of patients with DMD and skeletal muscle specimens of adult mdx mice, a widely studied animal model for DMD, for cTnT and cTnI using commercially available immunoassays and immunoblotting with well-characterized antibodies.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Patients.
EDTA blood was drawn from 14 patients (median age,
7.5 years; minimum–maximum, 5.7–19.4 years) with DMD attending the
Department of Pediatrics at the University of Freiburg. The diagnosis
of DMD was based on standard clinical protocols of the Departments of
Pediatrics at the Universities of Innsbruck and Freiburg based on the
detection of the characteristic mutations in the dystropin gene by PCR
testing and the work up of muscle biopsy specimens demonstrating
typical morphological changes and the absence of dystropin. In
addition, remnants of skeletal muscle biopsies that were taken for
diagnostic purposes during the early stage of disease from three
patients (4.5–6 years; one tissue specimen from the Department
of Anatomy 3, University of Vienna, without an available blood sample;
two specimens from the Department of Pediatrics at the University of
Innsbruck) with DMD were available for Western blot analysis. In all
patients creatinine was within reference values. A careful
clinical history, chest x-ray, electrocardiogram, and echocardiogram
were used to assess myocardial function. Blood samples were immediately
centrifuged at 2000g for 15 min at room temperature
(25 °C) and frozen at 20 °C until further analysis. Tissue
samples were shock-frozen in liquid nitrogen after excision and stored
at -80 °C. Healthy tissue from the heart and skeletal muscle and
nongravid uterus were obtained as negative controls at the autopsy of a
15-year-old victim of an accident. Purified human cTnT (HyTest)
served as positive control. All samples and tissue specimens were
collected in accordance with the Helsinki Declaration of 1975 as
revised in 1983.
homogenization and immunoblotting (western blot)
Muscle tissue of mdx mice and patients was cut into small pieces
in crude-muscle extraction buffer [10 µL of buffer for 1 mg of
muscle; buffer composition was as follows: 1.784 g of
Na4P2O7·10
H2O (40 mmol/L), 0.02 g of
MgCl2·4 H2O (1 mmol/L),
0.038 g of EGTA (1 mmol/L), 0.002 g of phenylmethylsulfonyl
fluoride (0.1 mmol/L), 0.0005 g of Leupeptin, 0.00005 g of
Pepstatin A, 0.1 g of soybean trypsin inhibitor, and 100 mL of
distilled water] at 4 °C and further homogenized with a potter (B.
Braun) for 10 min. The homogenate was centrifuged at 1348g
for 10 min at 4 °C, and the supernatant was frozen at -80 °C
until further analysis.
Protein concentrations were determined by the Bradford dye-binding
procedure (cat. no. 500-0006; Bio-Rad Laboratories GmbH). Either 28
µg of mdx tissue homogenate or 34 µg of human tissue homogenate was
loaded onto 12% ready-to-use SDS-Minigels (cat. no. 161-0900; Bio-Rad)
and separated at 150 V and 14 °C for 
90 min. Proteins were then
transferred onto nitrocellulose by a MiniTransfer-Blot Electrophoretic
Transfer Cell (cat. nos. 170-3930 and 170-3935; Bio-Rad) at 75 V and
4 °C for 105 min.
Nonspecific binding sites were blocked by incubating the nitrocellulose for 40 h at 4 °C in 70 g/L bovine serum albumin (BSA) blocking solution (pH 7.4). The membranes were then washed three times with 1 mL/L Tween 20 (cat. no. 822184; Merck) in phosphate-buffered saline (PBS; pH 7.4). The nitrocellulose membrane was then incubated with one of three different monoclonal antibodies (MAbs) specific for cTnT [MAb M7 (stock solution, 8.5 g/L; gift of Roche, Penzdorf, Germany) at a 1:2000 dilution in PBS with 50 g/L BSA; MAb 7G7 (stock solution, 5.1 g/L; cat. no. 4T19; HyTest) at a 1:12 000 dilution in PBS with 50 g/L BSA; or MAb 1F2 (stock solution, 8 g/L; cat. no. 4T19; HyTest) at a 1:12 000 dilution in PBS with 50 g/L BSA] and one antibody that recognizes all TnT isoforms (Sigma clone JLT-12, cat. no. T-6277; Sigma Immuno Chemicals) at a 1:3000 dilution in PBS with 50 g/L BSA for 60 min at room temperature. An antibody specific for cTnI [MAb 11E12, detection epitope 31–34 specific for cTnI (23) (stock solution, 2.1 g/L; gift of Sanofi Diagnostics Pasteur, Montpelier, France) at a 1:12 000 dilution for mdx tissue or a 1:6000 dilution for human tissue in PBS with 50 g/L BSA] was then added, and the membrane was incubated for 30 min. An antibody against cardiac and skeletal TnI [biotinylated MAb 10F2, detection epitope 190–196, which is common to all three TnI isoforms (23) (gift of Sanofi Diagnostics Pasteur, Montpelier, France), 1:20 000 dilution in PBS with 50 g/L BSA for mdx tissue or 1:6000 dilution for human tissue] conjugated with streptavidin-horseradish peroxidase (cat. no. RPN 2195; Amersham Life Science) at a 1:6000 dilution in PBS with 50 g/L BSA was added, and the membrane was incubated for 60 min at room temperature.
The nitrocellulose membrane was then washed three times with Tween 20
(3 mL/L for cTnT and cTnI and 1 mL/L for TnT) in PBS (pH 7.4), and
incubated with peroxidase-labeled secondary rat antibody anti-mouse IgG
(cat. no. NA 931; Amersham Life Science) at a 1:6000 dilution for 20
min for all primary antibodies except for MAb 10F2. The membrane was
again washed three times with Tween 20 (5 mL/L for cTnT and 3 mL/L for
all other antibodies) in PBS (pH 7.4). Finally, the nitrocellulose
membrane was incubated for 1 min with ECLTM
substrate (cat. no. RPN 2106; Amersham Life Science) and exposed to
x-ray films (HyperFilmTM ECL; cat. no.
HP79NA; Amersham) for 20 s. Molecular mass markers [Sigma
MarkerTM (low-molecular mass range; cat. no.
M-3913), biotinylated SDS-MG-marker (cat. no. 100B-Kit; Sigma), or ECL
protein molecular mass marker (cat. no. RPN 2107; Amersham)] as well
as positive and negative controls were included in each analysis. The
bands on x-ray films were evaluated visually as well as by scanning
with a densitometer (Elscript 440; ATH Analyzentechnik Hirschmann GmbH)
using the two-dimensional evaluation program.
quantification of cTnT, cTnI, myoglobin,
ckmb, and ck
Measurement of cTnT in plasma of patients was performed by
second-generation ELISA on the ES300 analyzer (Roche) with MAb M7, the
detection antibody specific for cTnT (4)(24).
MAb M7 was also used for immunoblotting (see above). MAb M7 detects
epitope 125–131 of cTnT. This epitope is in the middle of the
molecule, and differences between human fetal and adult cTnT are found
only within the first 30 amino acids. Therefore, MAb M7 recognizes both
the adult and fetal isoforms of human cTnT. MAb M7 does not react with
the amino acid sequences with other TnT isoforms, and therefore, it
recognizes only the cardiac isoform of human TnT without
cross-reactivity with the skeletal isoforms of TnT. The
detection limit for this assay is 0.03 µg/L, and the upper reference
limit is 0.1 µg/L. The reported intraassay imprecision
(CV) at the lower end of the measuring range is 3.3% (at 0.27
µg/L), and the interassay imprecision is 5.4% (at 0.26 µg/L)
(4).
cTnI, myoglobin, and CKMB were quantified by ELISA on the ACCESS System (Beckman Diagnostics). The detection limit and the upper reference limit in this assay are 0.03 and 0.1 µg/L, respectively, for cTnI; 8.9 and 70 µg/L, respectively, for myoglobin; and <0.3 and 6 µg/L, respectively, for CKMB. The reported intraassay imprecision at the lower end of the measuring range is 5.6% (for 0.36 µg/L) and the interassay imprecision is 6.7% (for 0.30 µg/L). Total CK activity was measured by a standardized and optimized kinetic enzymatic method on a Hitachi 717 analyzer (Roche Diagnostics); activities at 25 °C are given.
statistics
Nonparametric statistical methods were used to describe
parameters, i.e., median, 25th, and 75th percentiles. The Spearman rank
correlation coefficient (r) was calculated: r
0.8 was considered a close correlation, 0.6 < r
< 0.8 a moderate correlation, and r <0.6 a weak
correlation. Results were considered statistically significant at
P <0.05.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
). Moreover, with non-isoform-specific antibodies for
TnT (MAb JLT-12) and TnI (MAb 10F2), no cardiac isoform expression
could be demonstrated in the same skeletal muscle samples, whereas the
skeletal isoforms of TnT and skeletal TnI bands were clearly seen (Fig. 2
).
|
|
human specimens
In human skeletal muscle samples of three DMD patients, no
evidence of either cTnT protein (molecular mass 39 kDa; MAb
M7) or cTnI protein expression (molecular mass 24 kDa; MAb 11E12)
could be seen by Western blot analysis (Fig. 3
). The absence of cTnT expression was also confirmed by two
other anti-cTnT antibodies (MAbs 7G7 and 1F2). However, in the
same specimens, we found strong signals for the skeletal
isoforms of TnT (molecular mass 31–33 kDa) and TnI (molecular mass
21 kDa; Fig. 4
). Thorough clinical histories, chest x-rays,
electrocardiograms, and echocardiograms showed no evidence of cardiac
involvement. The laboratory values for the two DMD patients attending
the Department of Pediatrics at the University of Innsbruck were as
follows: cTnT, 0.03 and 0.03 µg/L; cTnI, 0 and 0.02 µg/L;
myoglobin, 1232 and 168 µg/L; CKMB, 526.5 and 133.4 µg/L; CK, 3865
and 1328 U/L, respectively.
|
|
Plasma from 14 DMD patients did not reveal any relation of cTnT
and cTnI concentrations with clinical evidence for heart failure. One
patient had been treated for CMP, and two had early-stage CMP without
the necessity for drug treatment. cTnI concentrations remained below
the upper reference limit in all patients (0.01–0.1 µg/L). Nine
patients without CMP as well as two patients with CMP showed cTnI
concentration below the detection limit (<0.03 µg/L). Three patients
had detectable cTnI concentrations (two with CMP and one without CMP).
The cTnT concentration was increased (median, 0.11 µg/L;
maximum–minimum, 0.01–0.20 µg/L) in 50% of patients, and
the highest concentration was found in a patient without any signs of
cardiac failure. Two patients with early-stage CMP showed cTnT as well
as cTnI concentrations within the reference interval. cTnT and
cTnI concentrations did not differ between patients with or without CMP
(Fig. 5
). The only significant correlation was found for CK (median,
3938 U/L; range, 2763–5030 U/L) with age (median, 7.5 years; range,
6.8–10.9 years; r = 0.762, P = 0.004),
an established marker of DMD disease severity. In contrast we found no
correlation of CKMB, myoglobin, cTnT, and cTnI with age. CKMB (median,
260 µg/L; range, 206–378 µg/L) and myoglobin (median, 629 µg/L;
range, 508–776 µg/L) were strongly increased in all patients with
DMD and showed no relation with the presence of CMP.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
There was no evidence of either cTnI or cTnT protein expression in skeletal muscle samples of both mdx mice and DMD patients. Additionally, we used three different well-characterized antibodies for cTnT, which showed equal results. However, in the same samples, there was strong evidence of expression of the skeletal muscle isoforms of TnI and TnT. These findings are in contrast to the recent report of Ricchiuti and Apple (28), who found expression of a 150-bp cTnT amplicon in two of five patients with DMD. Although they demonstrated amplification for cTnT (150-bp), they did not show protein expression for cTnT in these DMD patients. Furthermore, patients with DMD were not well characterized in this study and it is not clear whether skeletal muscle biopsies were obtained from early-stage or end-stage DMD patients. Therefore, there is still not sufficient evidence at the protein level (28) that cTnT is reexpressed in DMD patients. In our study, we obtained samples of biopsies that were performed at an early stage of the disease to confirm and establish the diagnosis of DMD. We could not obtain any material from autopsies of patients with DMD or of DMD patients with end-stage disease. We did not find any reexpression of human adult cTnT in skeletal muscle in the early stage of DMD, but we cannot comment on or exclude reexpression of cTnT in regenerating skeletal muscle of DMD patients with the advanced stage of the disease. In our study, we could only investigate skeletal muscle specimens of three DMD patients, but none of them, and none of the six mdx mice, showed any sign of cTnT protein expression in skeletal muscle.
Ricchiuti et al. (24) demonstrated the variable presence of
cTnT isoforms in skeletal muscle specimens of patients with chronic
renal diseases. They reported the expression of a high-molecular mass
isoform of cTnT (39 kDa) detected by MAb M7 in some but not all
skeletal muscle biopsies of these patients, and of low-molecular mass
cTnT isoforms (34–36 kDa) in 20 of 45 skeletal muscle biopsies of
these patients detected by MAbs 11.7, 13-11, and JS-2. In contrast, we
could not find any evidence of cTnT expression using three different
and well-characterized antibodies against cTnT, neither in human (DMD
early stage) nor in mdx mouse (advanced disease stage) skeletal muscle
specimens.
Although the murine model is genetically identical to human DMD, a limitation of the mdx model is that it does not strictly parallel the histopathology and progression of human DMD. In contrast to human DMD, in mdx mice there is minimal fibrosis and fatty tissue replacement, and cellular necrosis is long compensated by regeneration of muscle fibers. Necrotic fibers start to appear after 3 weeks and become numerous after 4 weeks. During the disease, a lack of synchronization has been described, i.e., a craniocaudal gradient was found in the appearance of necrosis followed by regeneration. The degeneration and regeneration of mdx muscle is reported to occur essentially between the 3rd and 10th week (21). The mdx mice in our study were 8–10 weeks of age, and the muscle fibers showed the characteristic histological signs of adult regenerated fibers. We demonstrated that the mdx muscle specimens investigated in our study were affected by the disease. Despite that fact, we did not find any reexpression of cTnT in the musculus quadriceps femoris specimens of these mdx mice.
These controversial results of rather small investigations in DMD patients will have to be clarified in larger, preferably multicenter, studies with study populations that should ideally cover the whole spectrum of DMD disease stages. However, our findings, obtained with specific antibodies and with well-characterized DMD patients, may contribute to a better understanding of reexpression of cardiac troponins in DMD. We demonstrated that cardiac troponins are not expressed during the early stages of DMD in humans and are not expressed in end-stage disease in the mdx mouse model.
Nevertheless, the second-generation cTnT assay showed increased cTnT values in >50% of DMD patients without clinical evidence for cardiac involvement. Similar results have been reported by Baum et al. (4) and Müller-Bardorff et al. (27), who found increased cTnT concentration in patients with muscular dystrophy. It was demonstrated by ELISA and Western blot analysis that the antibodies used in the second-generation assay for cTnT reveal no or only extremely minor reactivity with skeletal TnT (27). Thus, cross-reactivity with skeletal muscle TnT cannot be the reason for the increased cTnT concentrations found in patients without evidence of cardiac failure.
Despite the increased plasma cTnT values, we could not demonstrate any reexpression of cTnT in skeletal muscle of patients with early-stage DMD. A possible explanation is that increased cTnT may reflect subclinical myocardial damage that cannot be detected with the currently available clinical methods for diagnosing cardiac involvement. Patients with end-stage DMD are a high-risk group for dilatative CMP (29). Hence, the sensitivity (30)(31) of the cTnT assay or the diagnostic time window of cTnT may exceed the sensitivity of the cTnI assay or the diagnostic time window of cTnI and allow the detection of minor myocardial damage with greater accuracy. cTnI increases and mostly peaks in parallel to cTnT after acute myocardial infarction (at least 4–5 days), but cTnT stays increased for at least 1 or 2 days longer than cTnI (32). However, we currently do not have convincing evidence for this hypothesis of a greater sensitivity of cTnT compared with cTnI from other clinical settings.
Similar discrepancies and unexpected increases of cardiac troponins have been also reported in patients with end-stage renal failure (33). It was suggested by the authors of that report that this discrepancy may in part be attributable to differences in the precision at the lower end of the measuring ranges of the assays used in their study. However, in contrast to their study, the troponin assays used in our study had a comparable imprecision at the lower end of the measuring range. Our cTnI ELISA on ACCESS (intraassay CV, 5.6% for 0.36 µg/L; interassay CV, 6.7% for 0.30 µg/L) shows a lower imprecision than the Stratus® II analyzer. Therefore, discrepancies between troponin concentrations found in our patients are not likely to be attributable to differences in assay precision. The comparative prognostic value of cardiac troponins in patients on chronic hemodialysis has already been investigated in several smaller studies (34)(35). Both increased cTnT and cTnI appear to predict cardiac complications in this patient population, but the currently available published data do not allow the conclusion that one troponin is superior to the other for cardiac risk stratification in this clinical setting.
In the present study, the cardiac troponins in DMD patients did not correlate with other cardiac markers or with age, which is the best marker for the assessment of disease severity. CK showed a 20- to 50-fold increase in plasma samples of patients with DMD compared with controls and was the only marker that correlated closely with age. In previous studies, maximum activities for CK were observed in patients 2–5 years of age (36)(37), and with progression of the dystrophic process, activities in serum decreased (38). CKMB showed equally strong increases in plasma concentrations. We confirmed the previously reported high percentage of CKMB increases in patients with DMD; CKMB is not a suitable cardiac marker in DMD patients. Both troponins were markedly more specific markers in our patient population. This corroborates with earlier studies that reported increased CKMB in patients with DMD or with polymyositis (39)(40)(41). The increase in myoglobin is also consistent with earlier reports that describe higher CK and myoglobin concentrations in patients with DMD (42)(43).
In conclusion, no evidence for troponin reexpression was found in human (early-stage disease) and mdx mouse skeletal muscle (end-stage disease) samples. Discrepancies of cTnT and cTnI in plasma samples of DMD patients showed no relationship between both troponins and other clinical evidence for cardiac involvement. These clinical results obtained in a relatively small population cannot exclude cTnT reexpression and release from skeletal muscle in end-stage or advanced stages of DMD. The prognostic significance of plasma cTnT in patients with DMD remains to be clarified in larger prospective multicenter clinical trials.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The following articles in journals at HighWire Press have cited this article:
|
|
 |
|
  J S Hamilton and P C Sharpe Two cases of inflammatory muscle disease presenting with raised serum concentrations of troponin T J. Clin. Pathol., December 1, 2005; 58(12): 1323 - 1324. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. J. Freda, W. H. W. Tang, F. Van Lente, W. F. Peacock, and G. S. Francis Cardiac troponins in renal insufficiency: Review and clinical implications J. Am. Coll. Cardiol., December 18, 2002; 40(12): 2065 - 2071. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Fredericks, J. F. Murray, N. D. Carter, A. M.S. Chesser, S. Papachristou, M. M. Yaqoob, P. O. Collinson, D. Gaze, and D. W. Holt Cardiac Troponin T and Creatine Kinase MB Content in Skeletal Muscle of the Uremic Rat Clin. Chem., June 1, 2002; 48(6): 859 - 868. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
0.1 µg/L are within the reference limit.