24 research outputs found
Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients
<p>Abstract</p> <p>Background</p> <p>Calretinin is one of the well-established immunohistochemical markers in the diagnostics of malignant mesothelioma (MM). Its utility as a diagnostic tool in human blood, however, is scarcely investigated. The aim of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for human calretinin in blood and to assess its usefulness as a potential minimally invasive diagnostic marker for MM.</p> <p>Methods</p> <p>Initially, attempts were made to establish an assay using commercially available antibodies and to optimize it by including a biotin-streptavidin complex into the assay protocol. Subsequently, a novel ELISA based on polyclonal antibodies raised in rabbit immunized with human recombinant calretinin was developed. The assay performance in human serum and plasma (EDTA/heparin) and the influence of calcium concentrations on antibody recognition were studied. Stability of spiked-in calretinin in EDTA plasma under different storage conditions was also examined. In preliminary studies serum and plasma samples from 97 healthy volunteers, 35 asbestos-exposed workers, and 42 MM patients were analyzed.</p> <p>Results</p> <p>The mean detection range of the new ELISA was 0.12 to 8.97 ng/ml calretinin. The assay demonstrated markedly lower background and significantly higher sensitivity compared to the initially contrived assay that used commercial antibodies. Recovery rate experiments confirmed dependence of calretinin antibody recognition on calcium concentration. Calcium adjustment is necessary for calretinin measurement in EDTA plasma. Spiked-in calretinin revealed high stability in EDTA plasma when stored at room temperature, 4°C, or after repeated freeze/thaw cycles. Median calretinin values in healthy volunteers, asbestos workers, and MM patients were 0.20, 0.33, and 0.84 ng/ml, respectively (p < 0.0001 for healthy vs. MM, p = 0.0036 for healthy vs. asbestos-exposed, p < 0.0001 for asbestos-exposed vs. MM). Median values in patients with epithelioid and biphasic MM were similar. No influence of age, gender, smoking status, or type of medium (plasma/serum) on calretinin values was found.</p> <p>Conclusions</p> <p>The novel assay is highly sensitive and applicable to human serum and plasma. Calretinin appears to be a promising marker for the blood-based detection of MM and might complement other markers. However, further studies are required to prove its usefulness in the diagnosis of MM patients.</p
Re-evaluation of histological diagnoses of malignant mesothelioma by immunohistochemistry
<p>Abstract</p> <p>Background</p> <p>In order to provide reliable tissue material for malignant mesothelioma (MM) studies, we re-evaluated biopsies and autopsy material from 61 patients with a diagnosis of MM from the period of 1980-2002.</p> <p>Methods</p> <p>Basic positive (Calretinin, EMA, Podoplanin, Mesothelin) and negative (CEA, Ber-Ep4) immunohistochemical (IHC) marker reactions were determined. If needed, more markers were used. Histological diagnoses were made by three pathologists. Survival data were calculated.</p> <p>Results</p> <p>49 cases (80%) were considered being MM by a high degree of likelihood, five more cases possible MM. Of the remaining seven cases, three were diagnosed as adenocarcinoma, three as pleomorphic lung carcinoma, in one peritoneal case a clear entity diagnosis could not be given. One of the possible MM cases and two of the lung carcinoma cases had this already as primary diagnoses, but were registered as MM.</p> <p>With a sensitivity of 100%, Calretinin and CEA were the most reliable single markers. The amount of MM cells with positive immunoreactivity (IR) for Podoplanin and Mesothelin showed most reliable inverse relation to the degree of atypia.</p> <p>In the confirmed MM cases, there had been applied either no IHC or between one and 18 markers.</p> <p>The cases not confirmed by us had either lacked IHC (n = 1), non-specific markers were used (n = 4), IR was different (n = 1), or specific markers had not shown positive IR in the right part of the tumour cells (n = 3).</p> <p>46 of the 49 confirmed and three of the not confirmed cases had been diagnosed by us as most likely MM before IHC was carried out.</p> <p>Conclusions</p> <p>In order to use archival tissue material with an earlier MM diagnosis for studies, histopathological re-evaluation is important. In possible sarcomatous MM cases without any positive IR for positive MM markers, radiology and clinical picture are essential parts of diagnostics. IHC based on a panel of two positive and two negative MM markers has to be adapted to the differential diagnostic needs in each single case. New diagnostic tools and techniques are desirable for cases where IHC and other established methods cannot provide a clear entity diagnosis, and in order to improve MM treatment.</p
Selective immunocytochemical localisation of calretinin in the human ovary1
Calretinin is a calcium-binding protein which is primarily expressed by certain cells of the nervous system, both central and peripheral. Its presence in nonexcitable cells has been little studied. Using a polyclonal antibody and paraffin sections we have analysed the presence of calretinin in the human ovary of different ages, and in polycystic ovaries. Our results revealed the selective presence of calretinin, specifically localised in the cells of the germinal epithelium, those of the theca interna and the theca lutein cells, in the cells of the neurovaso-epithelial association and of the canalicular structures of the mesovarium. Calretinin was also present in a few cells of the theca externa and some interstitial cells. No appreciable quantitative differences in the strength of the positive reaction were seen between the ovaries of different ages or between the normal and the polycystic ovaries. The presence of calretinin was confirmed by western blot analysis. The selective presence of calretinin in the human ovary, in androgenic cells and in the cells of the germinal epithelium is discussed in relation to its possible function as a Ca2+ buffe
Deformation and height anomaly of soft surfaces studied with an AFM
The atomic force microscope (AFM) can easily image 'hard' sample surfaces with atomic or molecular resolution. For ‘soft’ samples, such as polymers or biological objects, this resolution power is very difficult to reach, because the AFM tip can cause large deformation. This deformation is revealed in the touching regime of the force-versus-distance curve, or more directly in the force-versus-indentation curves. To obtain the force-versus-indentation curve of a soft sample, its force-versus-distance curve is corrected with the force-versus-distance curve measured with the same cantilever on a hard sample. We have measured the force-versus-indentation curves of different elastomers (polyurethane), rubber, cartilage and living cells and deduced a parabolic tip shape from these curves. We have also calculated the radius of curvature of the AFM tip to be 50-100 nm. The calculated ranges of the local Young's moduli E are 0.62.4 MPa for rubber, 0.160.6 MPa for cartilage, and 0.013-0.15 MPa for a living cell. This means that an applied force of 1-10 pN is required to obtain high-resolution images of a living cell with about 1 nm vertical deformation and only a few nm2 area of contact. Therefore, understanding the deformation mechanism is not only important for determining local elasticities but also to understand the 'height' information and the resolution limits of AFM images. Deformation without strong adhesive forces causes a soft sample on a hard substrate to appear thinner, a fact which has already been observed in many AFM images. Furthermore, if deformation of the soft sample occurs the applied force is overestimated. Therefore, high-resolution imaging of soft samples remains a challenge since the applied force needs to be in the pN range
Selective distribution of calretinin in adenocarcinomas of the human colon and adjacent tissues
The expression of calretinin, a calcium-binding protein, has been studied in a series of 82 human colorectal adenocarcinomas. In 22.5% of the cases, part of the tumor cells were calretinin-positive, whereas the cells of the normal and paratumoral mucosa were always negative. Two types of cells from the tumoral mass reacted positively and selectively with calretinin-antisera: the tumor cells and giant fibroblasts. The neurons of enteric ganglia and reactive mesothelial cells also reacted positively to the same antibody. The results obtained by immunochemistry have been confirmed by Western blot analysis and in situ hybridization for calretinin mRNA. There is a correlation between the expression of calretinin and the degree of differentiation of the tumor. Well-differentiated tumors express calretinin in only 5% of the cases, whereas this percentage is 20% for moderately differentiated tumors and 66.6% for poorly differentiated or undifferentiated tumors. We conclude that calretinin is expressed by most undifferentiated colorectal adenocarcinomas, but only by a limited number of cells in well-differentiated tumors. The degree of its expression coincides also with additional signs of malignancy, such as an increase in the number of metastases in the regional lymph nodes and in other organ