Immunoassays are used for many applications in various markets, from clinical diagnostics to the food industry, generally relying on gold-standard ELISAs that are sensitive, robust, and cheap but ...also time-consuming and labour intensive. As an alternative, we propose here the magnetically localized and wash-free fluorescence immunoassay (MLFIA): a no-wash assay to directly measure a biomolecule concentration, without mixing nor washing steps. To do so, a fluorescence no-wash measurement is performed to generate a detectable signal. It consists of a differential measurement between the fluorescence of fluorophores bound to magnetic nanoparticles specifically captured by micro-magnets against the residual background fluorescence of unbound fluorophores. Targeted biomolecules (antibodies or antigens) are locally concentrated on micro-magnet lines, with the number of captured biomolecules quantitatively measured without any washing step. The performance of the MLFIA platform is assessed and its use is demonstrated with several biological models as well as clinical blood samples for HIV, HCV and HBV detection, with benchmarking to standard analyzers of healthcare laboratories. Thus, we demonstrated for the first time the versatility of the innovative MLFIA platform. We highlighted promising performances with the successful quantitative detection of various targets (antigens and antibodies), in different biological samples (serum and plasma), for different clinical tests (HCV, HBV, HIV).
The magnetically localized and wash-free fluorescence immunoassay (MLFIA) is a no-wash assay for directly measuring biomolecule (antigen and antibody) concentration, without mixing nor washing steps, from a body fluid (serum and plasma).
We evaluated the possibility of using an experimental model of hepatocellular carcinoma to study oncomarkers of primary liver cancer and compared the diagnostic efficacy of alpha-fetoprotein and ...osteopontin in the experiment and in clinical practice. Experimental studies were performed on a model of hepatocellular carcinoma induced by administration of diethyl nitrosamine to Fisher-344 rats. In addition, the levels of α-fetoprotein and osteopontin were determined in 35 patients with hepatocellular carcinoma detected at stages I-II according to TNM classification. The proposed model of liver cancer in rats reflects the sequence of stages characteristic of hepatocellular carcinoma in humans: liver fibrosis—cirrhosis—cancer. This model is applicable for the study of tumor markers at the early stage of tumor development. Osteopontin was found to have a more powerful diagnostic potential then alpha-fetoprotein.
Summary
The production of T cell receptor αβ+ (TCRαβ+) T lymphocytes in the thymus is a tightly regulated process that can be monitored by the regulated expression of several surface molecules, ...including CD4, CD8, cKit, CD25 and the TCR itself, after TCR genes have been assembled from discrete V, D (for TCR‐β) and J gene segments by a site‐directed genetic recombination. Thymocyte differentiation is the result of a delicate balance between cell death and survival: developing thymocytes die unless they receive a positive signal to proceed to the next stage. This equilibrium is altered in response to various physiological or physical stresses such as ionizing radiation, which induces a massive p53‐dependent apoptosis of CD4+CD8+ double‐positive (DP) thymocytes. Interestingly, these cells are actively rearranging their TCR‐α chain genes. To unravel an eventual link between V(D)J recombination activity and thymocyte radio‐sensitivity, we analysed the dynamics of thymocyte apoptosis and regeneration following exposure of wild‐type and p53‐deficient mice to different doses of γ‐radiation. p53‐dependent radio‐sensitivity was already found to be high in immature CD4−CD8− (double‐negative, DN) cKit+CD25+ thymocytes, where TCR‐β gene rearrangement is initiated. However, TCR‐αβ−CD8+ immature single‐positive thymocytes, an actively cycling intermediate population between the DN and DP stages, are the most radio‐sensitive cells in the thymus, even though their apoptosis is only partially p53‐dependent. Within the DP population, TCR‐αβ+ thymocytes that completed TCR‐α gene recombination are more radio‐resistant than their TCR‐αβ− progenitors. Finally, we found no correlation between p53 activation and thymocyte sensitivity to radiation‐induced apoptosis.
Sorting and recovering specific live cells from samples containing less than a few thousand cells have become major hurdles in rare cell exploration such as stem cell research, cell therapy and cell ...based diagnostics. We describe here a new technology based on a microelectronic chip integrating an array of over 100,000 independent electrodes and sensors which allow individual and parallel single cell manipulation of up to 10,000 cells while maintaining viability and proliferation capabilities. Manipulation is carried out using dynamic dielectrophoretic traps controlled by an electronic interface. We also demonstrate the capabilities of the chip by sorting and recovering individual live fluorescent cells from an unlabeled population.
New, ultrasmall nanoparticles with sizes below 5 nm have been obtained. These small rigid platforms (SRP) are composed of a polysiloxane matrix with DOTAGA (1,4,7,10‐tetraazacyclododecane‐1‐glutaric ...anhydride‐4,7,10‐triacetic acid)–Gd3+ chelates on their surface. They have been synthesised by an original top‐down process: 1) formation of a gadolinium oxide Gd2O3 core, 2) encapsulation in a polysiloxane shell grafted with DOTAGA ligands, 3) dissolution of the gadolinium oxide core due to chelation of Gd3+ by DOTAGA ligands and 4) polysiloxane fragmentation. These nanoparticles have been fully characterised using photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), a superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR) to demonstrate the dissolution of the oxide core and by inductively coupled plasma mass spectrometry (ICP‐MS), mass spectrometry, fluorescence spectroscopy, 29Si solid‐state NMR, 1H NMR and diffusion ordered spectroscopy (DOSY) to determine the nanoparticle composition. Relaxivity measurements gave a longitudinal relaxivity r1 of 11.9 s−1 mM−1 per Gd at 60 MHz. Finally, potentiometric titrations showed that Gd3+ is strongly chelated to DOTAGA (complexation constant logβ110=24.78) and cellular tests confirmed the that nanoconstructs had a very low toxicity. Moreover, SRPs are excreted from the body by renal clearance. Their efficiency as contrast agents for MRI has been proved and they are promising candidates as sensitising agents for image‐guided radiotherapy.
From the top down: Ultrasmall nanoparticles with a sub‐5 nm size have been synthesised by using a top‐down route. The nanoparticles are composed of a polysiloxane matrix holding Gd–DOTA chelates (DOTA=1,4,7,10‐ tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). In rats, they have shown interesting properties as theranostic agents for radiosensitisation guided by magnetic resonance imaging.
was to identify the most effective serum tumor markers for early diagnosis of hepatocellular carcinoma based on the combination of diagnostic characteristics and correlations.
There were observed 55 ...patients with chronic hepatitis C in the stage of liver cirrhosis with a verified diagnosis of hepatocellular carcinoma. The control group consisted of 55 patients with chronic hepatitis C at the stage of liver cirrhosis without hepatocellular carcinoma, comparable to the experimental group in terms of basic clinical profile. The following tumor markers were estimated in both groups: alpha-fetoprotein (AFP), alpha-fetoprotein-L3 (AFP-L3), annexin A2 (ANXA2), heparin-binding growth factor Midkine (MDK), glypican-3 (GPC3), des-gamma-carboxyprothrombin (DCP, PIVKA-II), dickkopf-related protein 1 (DKK-1), osteopontin (OPN), and Golgi protein 73 (GP73). There were also evaluated such indices as diagnostic sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio of a positive test, the possible correlation between alpha-fetoprotein and other tumor markers. The area under the ROC curve (AUC) was calculated at the 95% confidence interval.
The greatest sensitivity was revealed when using heparin-binding growth factor, annexin A2, osteopontin. Alpha-fetoprotein, alpha-fetoprotein-L3, glypican-3, des-gamma-carboxyprothrombin, dickkopf-related protein 1 had the best specificity. AUC>0.75 was found in annexin A2, heparin-binding growth factor, glypican-3, des-gamma-carboxyprothrombin, osteopontin, Golgi protein 73. The likelihood ratio of a positive test result was the highest for glypican-3. A significant correlation was found between alpha-fetoprotein and alpha-fetoprotein-L3, annexin A2, des-gamma-carboxyprothrombin.
According to the aggregate indicators of diagnostic efficiency, heparin-binding growth factor, glypican-3, and osteopontin are the most promising tumor markers of those studied. When they are used, integral AUC values are above the average, the level of these tumor markers in the blood of patients with hepatocellular cancer does not correlate with alpha-fetoprotein. They are applicable for diagnosing liver cancer in AFP-negative patients. The combined use of AFP + GPC3, AFP + OPN has already shown their advantages. However, the efficacy of the combination of AFP + MDK, GPC3 + OPN has not been determined yet; therefore, significance of the combined use of these tumor markers in the diagnosis of liver cancer should be investigated in the near future.
Hepatitis B and C viruses (HBV and HCV) cause chronic hepatitis and hepatocellular carcinoma (HCC) by poorly understood mechanisms. We show that cytokines lymphotoxin (LT) α and β and their receptor ...(LTβR) are upregulated in HBV- or HCV-induced hepatitis and HCC. Liver-specific LTαβ expression in mice induces liver inflammation and HCC, causally linking hepatic LT overexpression to hepatitis and HCC. Development of HCC, composed in part of A6
+ oval cells, depends on lymphocytes and IKappa B kinase β expressed by hepatocytes but is independent of TNFR1. In vivo LTβR stimulation implicates hepatocytes as the major LT-responsive liver cells, and LTβR inhibition in LTαβ-transgenic mice with hepatitis suppresses HCC formation. Thus, sustained LT signaling represents a pathway involved in hepatitis-induced HCC.
Summary
Intrahepatic lymphocytes are believed to be involved in the immunopathogenesis of hepatitis C virus (HCV) infection and the evolution of HCV‐induced hepatitis. In the present study, we ...examined the three main intrahepatic lymphocyte subsets, namely CD3+CD56− conventional T lymphocytes, CD3+CD56+ natural T (NT) lymphocytes and CD3−CD56+ natural killer (NK) lymphocytes in HCV‐infected patients. The proportion of each lymphocyte subset was evaluated both in liver biopsies and in samples of peripheral blood lymphocytes (PBL) by flow cytometry in 21 patients with histologically proven chronic hepatitis C. Simultaneously, alanine aminotransferase (ALT) levels, viral load and histological lesions were assessed. Neither NT nor NK populations correlated with any biochemical, viral or histological parameters. Furthermore, Vα24+ NT lymphocytes showed no preferential enrichment in the liver of HCV‐infected patients. Regarding conventional T lymphocytes, a highly significant linear correlation was found between intrahepatic CD3+CD56− T lymphocytes and the Knodell score, a numerical score for assessing histological activity and fibrosis (r = 0·715, P < 0·0001) and more specifically with the periportal necrosis parameter, which is the main lesion of chronic hepatitis C. In addition, analysis of the peripheral compartment revealed a high correlation between values of CD3+CD56− lymphocytes and both Knodell score (r = 0·624, P = 0·003) and serum ALT levels and again with periportal necrosis. The strong correlation between the proportion of peripheral CD3+CD56− conventional T lymphocytes and the severity of hepatic lesions leads us to propose that evaluation of this accessible peripheral population could be used as an indicator test for the severity of histological lesions in chronic hepatitis C.
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Knowledge of the complete nucleotide sequence of the mouse TCRAD locus allows an accurate determination V-J rearrangement status. Using multiplex genomic PCR assays and real time PCR analysis, we ...report a comprehensive and systematic analysis of the V-J recombination of TCR alpha chain in normal mouse thymocytes during development. These respective qualitative and quantitative approaches give rise to four major points describing the control of gene rearrangements. (a) The V-J recombination pattern is not random during ontogeny and generates a limited TCR alpha repertoire; (b) V-J rearrangement control is intrinsic to the thymus; (c) each V gene rearranges to a set of contiguous J segments with a gaussian-like frequency; (d) there are more rearrangements involving V genes at the 3' side than 5' end of V region. Taken together, this reflects a preferential association of V and J gene segments according to their respective positions in the locus, indicating that accessibility of both V and J regions is coordinately regulated, but in different ways. These results provide a new insight into TCR alpha repertoire size and suggest a scenario for V usage during differentiation.
A retroviral element (multiple sclerosis-associated retrovirus, MSRV) defining a family of genetically inherited endogenous retroviruses (human endogenous retrovirus type W, HERV-W) has been ...characterized in cell cultures from patients with multiple sclerosis. Recently, MSRV retroviral particles or the envelope recombinant protein were shown to display superantigen activity in vitro , but no animal model has yet been set up for studying the pathogenicity of this retrovirus. In the present study, the pathogenicity of different sources of MSRV retroviral particles has been evaluated in a hybrid animal model: severe combined immunodeficiency (SCID) mice grafted with human lymphocytes and injected intraperitoneally with MSRV virion or mock controls. MSRV-injected mice presented with acute neurological symptoms and died within 5 to 10 days post injection. Necropsy revealed disseminated and major brain hemorrhages, whereas control animals did not show abnormalities ( P < .001). In ill animals, reverse transcriptase-polymerase chain reaction (RT-PCR) analyses showed circulating MSRV RNA in serum, whereas overexpression of proinflammatory cytokines such as tumor necrosis factor (TNF)- f and interferon (IFN)- n was evidenced in spleen RNA. Neuropathological examination confirmed that hemorrhages occurred prior to death in multifocal areas of brain parenchyma and meninges. Further series addressed the question of immune-mediated pathogenicity, by inoculating virion to SCID mice grafted with total and T lymphocyte-depleted cells in parallel: dramatic and statistically significant reduction in the number of affected mice was observed in T-depleted series ( P < .001). This in vivo study suggests that MSRV retroviral particles from MS cultures have potent immunopathogenic properties mediated by T cells compatible with the previously reported superantigen activity in vitro , which appear to be mediated by an overexpression of proinflammatory cytokines.
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