Distribution Of Troponin Research Articles

Distribution and prognostic value of high-sensitive troponin T measurement in patients with type 2 diabetes without cardiovascular disease

AimThe objective of this work was to define a value for the 99th percentile of high-sensitive troponin T and to evaluate the prognostic value of this biomarker in a population of patients with type 2 diabetes without a history of cardiovascular disease. MethodsIn this prospective, observational and analytic study, 482 patients with type 2 diabetes were enrolled. The patients were asymptomatic, with no history of cardiovascular events, renal insufficiency, or inflammatory or systemic disease. As events we considered a combined end point of major adverse cardiovascular events (MACE). Results94.9% of the patients had detectable troponin values, 20.7% of the patients had troponin values above the healthy population reference upper threshold (14pg/mL). The 99th percentile value for this patient population was 48pg/mL. Age, sex, the glomerular filtration rate and hypertension were associated with troponin values>14pg/mL. The incidence of MACE was 3.96 per 100 patients/year (p/y) between those with hs-TnT>14pg/mL and 1.07 per 100 p/y between those with hs-TnT≤14pg/mL (HR=3.78 CI95 1.49–9.58; p=0.005). ConclusionsThe 99th percentile value of troponin T in a population of patients with type 2 diabetes is 3-fold higher than the value proposed by the manufacturer for a healthy population. We also observed a significant difference in the distribution of troponin T values between men and women. This biomarker may be a valuable prognostic factor, since troponin T values above the reference upper threshold were associated with an increase in the risk of cardiovascular events in these patients.

Distribution and prognostic value of high-sensitive troponin T measurement in patients with type 2 diabetes without cardiovascular disease

AimThe objective of this work was to define a value for the 99th percentile of high-sensitive troponin T and to evaluate the prognostic value of this biomarker in a population of patients with type 2 diabetes without a history of cardiovascular disease. MethodsIn this prospective, observational and analytic study, 482 patients with type 2 diabetes were enrolled. The patients were asymptomatic, with no history of cardiovascular events, renal insufficiency, or inflammatory or systemic disease. As events we considered a combined end point of major adverse cardiovascular events (MACE). Results94.9% of the patients had detectable troponin values, 20.7% of the patients had troponin values above the healthy population reference upper threshold (14pg/mL). The 99th percentile value for this patient population was 48pg/mL. Age, sex, the glomerular filtration rate and hypertension were associated with troponin values>14pg/mL. The incidence of MACE was 3.96 per 100 patients/year (p/y) between those with hs-TnT>14pg/mL and 1.07 per 100 p/y between those with hs-TnT≤14pg/mL (HR=3.78 CI95 1.49–9.58; p=0.005). ConclusionsThe 99th percentile value of troponin T in a population of patients with type 2 diabetes is 3-fold higher than the value proposed by the manufacturer for a healthy population. We also observed a significant difference in the distribution of troponin T values between men and women. This biomarker may be a valuable prognostic factor, since troponin T values above the reference upper threshold were associated with an increase in the risk of cardiovascular events in these patients.

Implications of Adjustment of High-Sensitivity Cardiac Troponin T Assay

To the Editor: We read with great interest the letter published in September by Apple and Jaffe regarding the recent adjustment to the calibration of a high-sensitivity cardiac troponin T (hs-cTnT)1 assay (1). The authors raised several important questions regarding the clinical implications of this assay recalibration and pointed out that no correlation studies had been performed for the earlier and new reagent lots. Although we received no information from Roche Diagnostics in France, we observed a shift in the distribution of troponin T concentrations in our university hospital laboratory when we used new reagent lot 167650 instead of lot 164776. Indeed, the overall percentage of the results below the limit of detection (LoD) (<5 ng/L) decreased from 22.7% (from May 1 to June 15, 2012; n = 3696) to 5.8% (from June 20 to July 30, 2012; n = 3097), and the median reported concentration increased from 25.3 ng/L to 29.8 ng/L. We thus decided to measure hs-cTnT with the former and recalibrated lots (lot numbers 164776 and 167650, respectively) in samples available from a cohort of 311 elderly patients [median (interquartile range), 81.5 years (75.8–84.9 years)]. These …

Analytical characteristics of the Roche highly sensitive troponin T assay and its application to a cardio-healthy population

It is desirable that current assays for cardiac troponin (cTn) are able to meet the recommended criterion that the diagnosis and risk assessment of patients present with symptoms of myocardial infarction requires a rise and fall in cTn with at least one point above the 99th percentile of a reference population. We have evaluated the analytical characteristics of the new highly sensitive troponin T (hs-TnT) assay to see if it meets this criterion and applied it to a carefully defined, cardio-healthy Australian reference population. An imprecision profile was determined for the Roche hs-TnT assay (Roche Diagnostics, Sydney, Australia) using multiple samples analysed on nine separate occasions. The distribution of troponin T was determined using 104 samples from a cardio-healthy population. The new hs-TnT assay meets the specifications of a coefficient of variation of 10% at the 99th percentile of our cardio-healthy reference population. Of the 104 samples analysed 44 showed troponin T concentrations above the manufacturer's quoted limit of detection. Age and gender differences in the median and 99th percentile troponin T concentration were observed. The new hs-TnT assay shows improved precision and sensitivity at very low troponin concentration. We have shown that a significant number of individuals in this cardio-healthy population had detectable circulating troponin concentration. With many apparently healthy people having detectable troponin, clinical judgement will become more important in interpreting troponin results.

Periodic binding of troponin C.I and troponin I to tropomyosin-actin filaments.

We investigated the distribution of troponin C.I and troponin I along tropomyosin-actin filaments by immunoelectron microscopy and found that anti-troponin I antibody formed transverse striations at 38 nm intervals along the bundle of filaments of both troponin C.I-tropomyosin-actin and troponin I-tropomyosin-actin. Since the length of 38 nm corresponds to the repeating period of filamentous tropomyosin along actin double strands, the present study indicates that troponin I is located at a specific region of each tropomyosin, suggesting that a specific interaction between troponin I and tropomyosin is involved in determining the periodic distribution of troponin I along tropomyosin-actin filaments.

Immunocytochemical electron microscopic study and western blot analysis of troponin in striated muscle of the fruit flyDrosophila melanogaster and in several muscle cell types of the earthwormEisenia foetida

There is little information about troponin in invertebrate muscles, and no previous references to this protein in annelid muscles have been found. The aim of this paper was to study the presence and distribution of troponin in different muscle cell types from the earthworm Eisenia foetida (the muscular body wall, and the inner and outer muscular layer of the pseudoheart). These results were compared with those obtained in the transversely striated muscle of Drosophila melanogaster and in skeletal and smooth muscles of the mouse. Immunocytochemical electron microscopic study and Western blot analysis using anti-TnT antibodies were employed in this study. Troponin immunoreaction was detected in the mouse skeletal muscle, the fly flight muscle, and earthworm obliquely striated muscles (body wall musculature and inner muscular layer of the pseudoheart). Immunolabeling for TnT in all these muscle cells appeared in moderate amounts at any point along the sarcomere length, except for the central zone of the A band (H band). This suggests that troponin molecules were located along the thin filaments. The density of immunogold particles was similar in the three muscles, and thus the amount of troponin in each muscle type was proportional to the number and length of actin filaments in each. Troponin was found in neither the mouse smooth muscle nor the outer muscular layer of the earthworm pseudoheart. The latter muscle showed an ultrastructural pattern that was intermediate between obliquely striated and smooth muscle. The estimated molecular weight for TnT in the earthworm was 55 kDa; this is higher than the weight of this protein in the mouse skeletal muscle (40 kDa) but similar to that of the D. melanogaster muscle (52 kDa). Troponin is present in both types of striated muscle (transversely striated and obliquely striated) of the earthworm with a distribution that is very similar to that observed in the mammalian striated muscle. As in vertebrates, troponin is absent in the smooth muscle of the earthworm. Discrepancies in the classification of some invertebrate muscles are common in the literature, and the use of distinctive markers, such as troponin, may improve our understanding of the nature and properties of many invertebrate muscles showing an ultrastructural pattern that does not resemble any of the classic muscle types.

Patterns of troponin T expression in mammalian fast, slow and promiscuous muscle fibres.

The distribution of troponin T (TnT) species in typed single muscle fibres was analysed using one- and two-dimensional polyacrylamide gel electrophoresis (PAGE) and a monoclonal antibody specific for fast TnT. Fibres taken from erector spinae (Es), plantaris (Plt), diaphragm (Dia) and soleus (Sol) muscles of adult rabbits were pretyped as fast-twitch-glycolytic (FG), fast-twitch-oxidative-glycolytic (FOG), slow-twitch-oxidative (SO) or promiscuous (P) using a combination of histochemical staining and PAGE. Although none of the four size classes of TnT was either muscle or fibre type specific, their pattern of expression differed in each muscle and between the fibre types. FG fibres expressed TnT1f or TnT2f as predominant species, depending on the muscle; TnT3f and TnT4f were minor components. In contrast, all size classes of TnT were expressed in varying proportions in FOG fibres from Es and Plt, while those from Dia resembled FG fibres, expressing TnT1f as their major species. P fibres from Es, Plt, and Sol exhibited a distinctive pattern of fast TnT expression, TnT3f being the predominant species. Dia differed from the other muscles as TnT1f was the dominant fast TnT species in its P fibres as it is in the Dia fast fibres. Quantitative analysis of one- and two-dimensional gels revealed that the P fibres could be divided into two classes, those that exhibited discoordinate expression of fast and slow TnTs, myosin light chains and myosin heavy chains and those in which their expression was coordinate. In addition low levels of TnT4f were detected in SO fibres and of slow TnT in fast fibres.

Neural influences on the distribution of troponin I isotypes in the cat

Neural influences on the distribution of troponin I isotypes in the cat

Neural influences on the distribution of troponin I isotypes in the cat

Abstract An immunohistochemical technique was used to study changes in the distribution of fast and slow forms of troponin I (TN-I) in response to alterations in the nerve supply. Hind limb muscles from normal, spinal-isolated, and cordotomized cats, one leg of which had undergone cross innervation between slow (soleus) and fast (flexor hallucis longus, FHL) muscles, were examined. At 8 months after cross innervation of normal soleus by the FHL nerve, the number of fast TN-I-positive cells had increased from 0.26 to 22.1%. At 8 months after cross innervation of normal FHL muscle with the soleus nerve, the number of fast TN-I-positive cells had decreased from 86.5 to 30.5%. The number of intermediate cells staining for both fast and slow TN-I increased considerably after cross innervation of both soleus and FHL muscles. Spinal isolation by itself had a dramatic effect on the distribution of fast and slow TN-I, converting almost all the originally slow fibers in the FHL and 60.0% of the soleus fibers to fast TN-I-positive cells in 8 months. Cordotomy, in contrast, produced an increase of only 15.6% in the soleus, and did not change the FHL. There was no quantitative difference in the crossed and uncrossed muscles of spinal isolated cats. In cordotomized cats, cross innervation of the soleus by the FHL nerve resulted in 32.3% fast TN-I-positive cells, with some fiber type grouping. Thus, distribution of fast and slow forms of TN-I changed after each neural manipulation which altered amounts and patterns of muscle contraction and stretch.

Distribution of troponin C and protein activator of 3′,5′-cyclic nucleotide phosphodiesterase in vertebrate tissues

1. Troponin C-like proteins, found recently in various vertebrate tissues, have been isolated and identified. 2. Smooth muscle (gizzard and uterus), adrenal medulla, platelets and brain contain only one troponin C-like protein which is identical with the protein activator of 3′,5′-cyclic nucleotide phosphodiesterase. 3. The protein activator is also present in skeletal and cardiac muscle in addition to the presence of troponin C. 4. Fractionation of the homogenate of the investigated tissues at 100,000 g shows that protein activator is present both in the cytosol and in the particulate fraction. Both fractions seem to contain protein(s) able to bind protein activator in the presence of calcium.