Biomedical subjects
Publications and source records attributed to M Zaninotto.
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Myoglobin, a low molecular-weight heme protein (17800 D) present in both cardiac and skeletal muscle, is an old test with new perspectives. Advantages and disadvantages of myoglobin determination are well known. Myoglobin is the earliest known, commercially available, biochemical marker of acute myocardial infarction (AMI) and its rapid kinetics make it an early, good marker of reperfusion. However, since myoglobin is present in both skeletal and cardiac muscle, any damage to these muscle types results in its release into blood. Serum myoglobin levels are falsely elevated in conditions unrelated to AMI as skeletal muscle and neuromuscular disorders, renal failure, intramuscular injection, strenuous exercise, and after several toxins and drugs intake. New strategies for myoglobin measurement may resolve this limitation. These strategies include both the combined measurement of myoglobin and a skeletal specific marker (carbonic anhydrase III) or a cardiac specific marker (troponin I), as well as the myoglobin evaluation on serial samples. In particular, the diagnostic algorithm based on the combined measurement of myoglobin and troponin I, assuring a satisfactory analytical turnaround time, significantly improves the diagnostic efficiency of laboratory assessment of suspected AMI patients, allowing the successive monitoring of coronary reperfusion.
Diurnal variations in the excretion of bone resorption markers were assessed in order to identify the type of urine collection which provides the most information on bone resorption rate and its relation to measuring bone dynamics in a postmenopausal population. Sixty women, ages 43-67 and without disease or treatment known to affect bone mineral density, were divided into two groups on the basis of femoral mineral density T-score: <1.5 (Group I), >1.5 (Group II). Bone formation was assessed by measuring bone alkaline phosphatase activity and osteocalcin concentration, bone resorption by urinary hydroxyproline, pyridinoline and deoxypiridinoline, N-telopeptide, galactosyl hydroxylysine, and CrossLaps. To identify the more appropriate collection times, urine samples were collected from 7 am to 3 pm; from 3 pm to 11 pm; from 11 pm to 7 am. Twenty-four hour urine collection and first morning void urine samples were also measured. The findings suggest that nocturnal collection and first morning void samples provide the most reliable data on the rate of bone degradation, possibly showing bone loss not only in osteopenic patients but also in women with a low T-score. Nocturnal and first morning samples should therefore be recommended in order to standardize sample collection, as they enable an accurate assessment of bone resorption markers and improved comparability to results from different studies, as well as a less cumbersome collection modality.
Cardiac troponin T (TnT) is a regulatory contractile protein whose detection in the circulation has been shown to be a specific and sensitive marker for ischemic myocardial cell injury both in adult and pediatric populations. We measured serum cardiac TnT in 15 consecutive full-term neonates presenting with bradycardia and electrocardiographic features of transient myocardial ischemia. Their median TnT concentrations (0.5 microg/l, range 0.01-0.37) were statistically comparable to our laboratory reference values for healthy term newborns (median 0.17 microg/l, range 0.01-0.42) (p = NS), but significantly higher with respect to our reference limits for healthy adults (median 0.01 micog/l, range 0.01-0.1) (p < 0.05). Our data demonstrate high TnT levels in neonates during the first days of life with respect to adults and similar TnT concentrations in term infants with and without TMI.
Determination of myoglobin, a low molecular weight haeme protein (17.8 kDa), present in both cardiac and skeletal muscle, is an old test with new perspectives. Advantages and disadvantages of myoglobin determination are well known; recent availability of rapid and accurate methods for the assay of this protein has greatly enhanced interest in the clinical utilization of the test. However, since myoglobin is present in both skeletal and cardiac muscle, any damage to these muscle types results in its release in blood and, consequently, high levels of the protein are observed in conditions unrelated to acute myocardial infarction (AMI). New strategies for myoglobin measurement may resolve this limitation. These strategies include both the combined measurement of myoglobin and a skeletal specific marker (carbonic anhydrase III) or a cardiac specific marker (troponin I or T), as well as myoglobin evaluation on serial samples. In particular. the diagnostic algorithm based on combined measurement of myoglobin and troponins significantly improves diagnostic efficiency in laboratory assessment of suspected AMI patients. However, further efforts are necessary to improve the standardization of present methods for myoglobin measurement: the significant disagreement demonstrated between some commercially available assays should be carefully considered in clinical practice.
The presence of myocardial injury during non-surgical coronary revascularization has been evaluated by means of highly specific and sensitive biochemical markers. Troponin T, creatine kinase-MB isoenzyme mass concentration, and creatine kinase MB2/MB1 isoform ratio have been determined in 80 patients who underwent coronary revascularization with percutaneous transluminal coronary angioplasty (PTCA). Forty-five patients underwent balloon angioplasty, 15 rotational atherectomy, 10 directional atherectomy, and 10 elective coronary stenting. Serum concentration of the evaluated markers did not increase significantly after 57 uncomplicated revascularization procedures, including 15 rotablation procedures, nor after 8 PTCAs complicated by localized coronary type B and C dissections. Significant elevation of all markers above the upper limits of the reference interval (P < 0.05) was detected after occlusion of small side branches (< 0.5 mm diameter) in 5 patients. Creatine kinase MB2/MB1 isoform ratio was the earliest marker to increase. After recanalization of occluded vessels in 8/10 patients with 6-60 days old myocardial infarction only troponin T concentrations increased from a baseline of 0.28 microgram/l to a median peak of 0.80 microgram/l. This increase was statistically not significant (P = 0.12). In conclusion, myocardial damage was not detected following uncomplicated non-surgical revascularization obtained with different techniques. Markers of myocardial injury provide high sensitivity after small side branch occlusion.
In this study we assessed whether conditioned media from a human pancreatic cancer cell line (MIA PaCa 2) can interfere with some intracellular pathways involved in glucose metabolism in isolated rat hepatocytes. The hepatocytes, isolated from Male Wistar rats, were incubated with MIA PaCa 2-conditioned or nonconditioned media. Conditioned and nonconditioned hepatocytes were run for 120 min in the presence or absence of insulin (100 mM) and were sampled at fixed time intervals. Supernatant glucose levels decreased to a similar extent over time in both conditioned and nonconditioned hepatocytes, while lactate levels significantly increased in nonconditioned hepatocytes with respect to conditioned hepatocytes. A pyruvate kinase activity increase was observed only in nonconditioned hepatocytes and was biphasic in nature, since this increased activity was detected both after a few and after 30 min following insulin stimulation. The cyclic AMP level increase was significantly higher in conditioned than in nonconditioned hepatocytes. It appears that MIA PaCa 2 cells produce a factor(s) that may interfere with one of the insulin-mediated intracellular pathways of glucose metabolism, namely, glycolysis. This detrimental effect on glycolysis is supported by the blunted rise in lactate concentration in the medium after the glucose challenge. This substance(s) probably transfers its signal inside the target cells, activating the adenylate cyclase pathway. These results support the hypothesis that pancreatic cancer is the cause rather than the consequence of diabetes mellitus.
The aims of our study were to evaluate the plasma carboxypeptidase N activity in normal subjects and in patients with acute myocardial infarction and to delineate its relationship with creatine kinase-MB isoforms in monitoring of acute myocardial infarction, carboxypeptidase N being the major determinant of creatine kinase isoform conversion in plasma. The study was carried out in 34 healthy subjects and 19 patients with acute myocardial infarction diagnosed according to the World Health Organization (WHO) criteria in which the blood samples were collected immediately upon admission to the coronary care unit (median time 3.5 hours), every 4 to 6 hours for 24 hours, and every 12 hours until the third day post admission. Carboxypeptidase N activity, total creatine kinase, creatine kinase-MB mass concentration and creatine kinase-MB isoforms were determined in each sample from acute myocardial infarction patients, whereas only carboxypeptidase N and total creatine kinase activities were assayed in samples from healthy subjects. The results showed a high variability in carboxypeptidase N values among healthy subjects (median = 200 U/l; interquartile range = 190-247 U/l) and in the first available samples from acute myocardial infarction patients (median = 213 U/l; interquartile range = 234 U/l) without significant differences between groups and without a correlation between carboxypeptidase N and creatine activities either in healthy subjects or in acute myocardial infarction patients; in the latter group, however, a significant correlation (p < 0.01) with creatine kinase-MB calculated on all samples, was observed. In acute myocardial infarction patients carboxypeptidase N showed time-related variations, reaching the highest levels about 48 h after onset of chest pain. A statistically significant difference in carboxypeptidase N values (p = 0.0001) was found before and after creatine kinase-MB peak values as well as before and after MB2/MB1 normalization. Worthy of note is the finding that in two acute myocardial infarction patients presenting MB2/MB1 ratios lower than the cutoff value (1.5) throughout the period of observation, the baseline values for carboxypeptidase N were higher than in other patients studied. Our results suggest that the increase of carboxypeptidase N activity after infarction could be induced by an increase in endogenous substrate concentrations, in particular creatine kinase-MB released from damaged myocardium. Furthermore, high baseline levels of carboxypeptidase N will reduce the diagnosis efficiency of creatine kinase-MB isoforms in the diagnosis of acute myocardial infarction.
We present the case of a two and a half year old child with idiopatic dilated cardiomyopathy and end-stage congestive heart failure (NYHA III-IV) who underwent "partial ventriculectomy". The operation was performed under normothermic cardiopulmorary bypass and normothermic oxygenated blood cardioplegia and consisted of removal of a large wedge of muscle from the lateral wall of the left ventricle beginning at the apex and extending between the papillary muscles, ending proximal to the mitral annulus. Pre-operative the left ventricular ejection fraction (EF) was 13% by echocardiography and 20% by radionuclide ventriculography. Postoperative avaliation showed improvement of EF to 50% and 30%, respectively. The child was in functional class I (NYHA) on discharge from hospital (16th postoperative day).
OBJECTIVES: The evaluation of "new" and "traditional" markers of osteoblastic and osteoclastic activity, in patients with bone metastases. DESIGN AND METHODS: Our series consist of 40 patients with clinical, radiological, and scintigraphic evidence of bone metastases, and 40 age-matched healthy subjects. In all samples, traditional markers were evaluated by measuring total alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TrACP) activity, and osteocalcin (BGP) concentration. To assess new biochemical bone markers, bone isoenzyme of alkaline phosphatase (ALP-B) activity, carboxyterminal propeptide of type I procollagen (PICP), and carboxyterminal telopeptide of type I collagen (ICTP) concentrations were measured. RESULTS: Our findings showed that the best diagnostic efficiency is provided by ICTP (0.94) followed by total ALP (0.90), ALP-B (0.80), and TrACP (0.76). The efficiency of BGP and PICP was, instead, very low (0.64 and 0.60, respectively). CONCLUSION: Our results confirm the utility of the new serum markers such as ALP-B and ICTP assays in detecting bone metastases.
OBJECTIVES: Amniotic fluid alpha1-microglobulin (alpha1-m) and beta2-microglobulin (beta2-m) levels, as well as N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) activities, were measured in the course of uncomplicated pregnancies to assess their variations as gestation progresses. DESIGN AND METHODS: Samples were obtained from 141 healthy pregnant women divided into three groups on the basis of gestational stage. Quantitative estimation of proteins was performed immunometrically and enzyme activities were determined spectrophotometrically. RESULTS: It was found that, during pregnancy, alpha1-m and beta2-m concentrations as well as AAP activity significantly decrease, although their reduction patterns vary. Controversial results were found for NAG activity: the normalization of values for amniotic fluid creatinine significantly changed the reduction pattern of this enzyme. No statistically significant differences were found between male and female fetuses for amniotic fluid values of the biochemical substances studied. CONCLUSIONS: The behavior observed for alpha1-m, beta2-m, and AAP might be linked to the progressive development and maturation of fetal renal tubular function. Amniotic fluid total NAG activity seems not to depend only on fetal urinary excretion.
The aim of our study was to evaluate the clinical relevance of serum troponin I (TnI) as a marker of ischemic myocardial injury by using an automated fluoroenzymometric assay. The reference range for serum TnI was established by measuring serum TnI concentrations in blood from 75 healthy donors. The concentration was then compared with serum creatine kinase (CK) activity, CK-MB mass, and myoglobin concentrations in 20 patients with myocardial infarction diagnosed according to the WHO criteria, 20 patients with chest pain of nonischemic origin, 9 patients with unstable angina, 11 with stable angina, 11 patients with chronic muscular diseases, 6 patients with muscular trauma without chest contusion, and 13 patients with chronic renal disease. We found that: (a) 99% of the blood donors had TnI concentrations <0.26 microgram/L (detection limit of the assay in our study); (b) TnI values in acute myocardial infarction (AMI) patients 4 h after onset of chest pain showed a sensitivity of 0.769 and a specificity of 1.0 at a decisional concentration for AMI of 1 microgram/L, even in the presence of severe skeletal muscle injuries or renal diseases; (c) the increase in TnI concentrations after infarction (interquartile range 3.25-6 h) and the peak occurred later (interquartile range 11.5-24 h) than the rise found in myoglobin and CK-MB, but the increase persisted much longer (>96 h); (d) receiver-operating characteristic curve analysis showed the high diagnostic accuracy of TnI in diagnosing AMI even in patients in whom traditional biochemical markers are adversely influenced by underlying clinical situations.
We evaluated a new analyzer (Cardio REP) specifically designed for cardiac CK-MB isoenzyme and isoforms activity, with a performance time of 24 minutes. Ten AMI patients, with times elapsed between the onset of chest pain and admission to hospital ranging from 30 minutes to 4 hours, were monitored every 3-4 hours until the 16th hour of hospitalization. In each serum sample, in addition to total CK-MB and CK-MB isoforms measured by the Cardio REP analyzer, we also assayed total CK activity, CK-MB activity by immunoinhibition method, CK-MB mass concentration, CK-MB isoforms by REP method, troponin T, and myoglobin. The precision study demonstrated acceptable within assay and between assay CVs% for total CK-MB (8.1 and 10.4), MB1 (9.1 and 14.2), and MB2 (9.1 and 8.2) isoforms. The method was found to be linear up to 371 U/L for MB2 isoform fraction and up to 516 U/L for total CK-MB. Results for CK-MB obtained with the Cardio REP correlated well with those for CK-MB activity obtained with the immunoinhibition method (r = 0.869) and those of CK-MB mass concentration (r = 0.923). The sensitivity of the Cardio REP CK isoforms method was found to be greater than that of the REP CK isoforms method. Time to first increased value of MB2/MB1 ratio and MB2 isoform was earlier in comparison to that for CK-MB mass concentration and similar to that for myoglobin, a marker that, however, lacks specificity. The diagnostic efficiency of CK-MB isoforms and the availability of a real-time, fully automated method for their measurement suggest that utilization of this biochemical marker in emergency for the early diagnosis of AMI.
Plasma von Willebrand factor (vWf) displays a complex pattern of repeating multimers, whose heterogeneous size distribution seems to depend on the proteolytic cleavage of the constituent vWf subunit. Smaller vWf multimers are thought to derive by proteolytic cleavage of the larger forms. To clarify the relationship between large multimer representation and the structure of small vWf oligomers, DDAVP was infused in patients with type-2A and -2B von Willebrand disease (vWd) variants which lack circulating high vWf forms. Before infusion, high-resolution multimer analysis demonstrated a more pronounced representation of the satellite bands of each oligomer, mainly concerning fast-moving components, especially in type 2B vWd. After DDAVP, in type-2A vWd each oligomer displayed a different organization depending on whether restoration of large vWf multimers occurred. The lack of large vWf multimer restoration, as shown in citrated samples, was associated with the fast band being significantly more represented than the slower, and almost similar to the central component. In contrast, when the high-molecular-weight vWf forms were restored, as occurred in the samples collected in the presence of protease inhibitors, the relative representation of the fast- and slow-moving bands was similar to that of normal samples. In type-2B vWd, regardless of the anticoagulant used, DDAVP infusion did not restore large vWf multimers, and each oligomer displayed a significant increase in both the central band and fast-moving satellite, the fast being even more highly represented. These findings suggest that, regardless of the origin, the disappearance of large circulating multimers in type-2A and -2B vWd induces an increased representation of the fast-moving satellite of the low-molecular-weight multimers. Moreover, the time course of large and low/intermediate multimer decrease and increase provides a further demonstration that low vWf multimers derive from the larger ones, and that mainly the fast-moving band of the oligomer is involved.
Renal function may be compromised by extrahepatic cholestasis. In this context, the nephrotoxic role of bile salts is well known. Recently, however, it has been claimed that other factors, such as lipid peroxides, are involved. We therefore created bile duct ligation in 40 Sprague-Dawley rats. During the follow-up (from 1 to 28 days), significant variations were found in liver histological parameters, but not in renal morphology. Fourteen days after ligation, significant increases were found in serum and urinary thiobarbituric-acid-reactive species and phospholipase A2 (indirect indices of lipid peroxidation), whereas 8-10 days after ligation, a significant decrease was observed in erythrocytic and hepatic GSH levels. The variations in urinary thiobarbituric-acid-reactive species and in phospholipase A2 were not correlated with concomitant variations in the sera. Urinary lipid peroxides were directly correlated with the degree of liver morphological alterations and inversely with circulating GSH. Urinary outputs of lipid peroxides, phospholipase A2 and N-acetyl-glucosaminidase were correlated with each other. These results suggest that there is an imbalance in the oxidative-antioxidant hepatic system in experimental extrahepatic cholestasis. The reduced bioavailability of blood GSH may alter the oxidative equilibrium in other organs, such as the kidney, triggering and favoring the lipoperoxidative cascade.
Because the concentration of serum myoglobin (Mb) increases within 2 to 4 hours after the first sign of acute myocardial infarction, it has been proposed as an early marker of the condition. Our aim was to evaluate a new assay that provides a rapid, quantitative determination of Mb (Baxter Stratus Myoglobin) based on the radial partition technique. We compared the results obtained by this technique with those from nephelometric and radioimmunoassay methods. A significant agreement was observed, the correlation coefficients (r) being 0.999 and 0.996, respectively. The method evaluated provided good reproducibility with CVs between 3.14% and 4.87%, and its linearity and analytical sensitivity were satisfactory. The clinical evaluation of this assay demonstrates that Mb increases in serum of patients with acute myocardial infarction before total creatine kinase and creatine kinase MB isoenzyme. Mb concentration shows an early peak and earlier return to normal values after the necrosis compared to enzymatic activities. Moreover the assay is rapid and fully automated. The method is therefore considered appropriate for contributing to the early diagnosis of AMI in clinical laboratories.
The efficacy of bone alkaline phosphatase (ALP) isoenzyme measurement using lectin precipitation in confirming metastatic bone lesions was compared with total ALP and osteocalcin assay in serum. Sixty-five patients with cancer and metastases to bone (n = 44), liver (n = 15) or lymph nodes (n = 6) as well as 33 healthy adults were studied. Assay of bone ALP is as sensitive but more specific than assay of total ALP in the identification of bone metastases. On the other hand, bone ALP did not correlate with osteocalcin, as is the case in other bone diseases. In the serial monitoring of nine patients with skeletal metastases, bone ALP correlated well with the presence of pain and the progression or regression of metastatic spread.