1,720,963 research outputs found
High-yield and high-degree purification of human alpha-fetoprotein produced by adaptation of the human hepatoma cell line Hep G2 in a serum-free medium.
No full textThe human hepatoma cell line Hep G2 secretes both albumin and alpha-fetoprotein when grown in the presence of serum. The present report describes how adaptation to growth in serum-free medium results in a progressive switch in the expression of the two proteins; i.e., alpha-fetoprotein becomes the main protein secreted while albumin production is greatly reduced. The culture supernatant obtained, being very enriched in the protein, allows the development of a purification procedure by preparative electrophoresis. By this procedure it is possible to easily obtain large amounts of alpha-fetoprotein from a constant and unlimited source. The availability of these protein preparations should improve the reproducibility and the quality of standardization in clinical immunoassays for alpha-fetoprotein and should permit a more accurate study of the structure and biological functions of the protein
Characterization of in vitro expressed human alpha-fetoprotein as highly reproducible reference material for clinical immunoassays.
No full textScreening e diagnosi precoce dei carcinomi colon-rettali. Purificazione del probe neu: analisi metodologica.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Human alfa-fetoprotein produced from hep G2 cell line: Structure and heterogeneity of the oligosaccharide moiety
No full textThe carbohydrate moiety of human -fetoprotein, an RMM 67000 glycoprotein produced in a hepatoma cell line (Hep G2), was investigated by the combined use of high-resolution chromatographic techniques and mass spectrometry. Fast atom bombardment mass spectrometric (FABMS) and reversed-phase high-performance liquid chromatographic analysis of -fetoprotein obtained from a large-scale cell culture following tryptic and peptide N-glycanase F hydrolysis demonstrated that the protein contains a single glycosylation site at level of asparagine 232. Further, electrospray mass spectrometric measurement of the intact protein molecular mass showed that two main glycoforms are present. The complete definition of the structural heterogeneity of the oligosaccharide moiety was achieved by high-performance anion-exchange chromatography with pulsed amperometric detection together with carbohydrate mapping by FABMS of the released oligosaccharides demonstrating (i) that the glycosylation produced by cell culture is of the biantennary complex type typical of human hepatoma -fetoprotein and (ii) the presence of two main structures in a ratio of about 2:1 differing in the presence of a fucose residue in the N-acetylglucosamine in the non reducing portion of the molecule
Unique structure of glycopeptide from alpha-fetoprotein produced in human hepatoma cell line, as determined by 1H-nuclear magnetic resonance spectroscopy.
No full textDetermination of alpha-fetoprotein is used in diagnosis of tumors and neural tube defects. A good reliable source of alpha-fetoprotein would be an obvious advantage to the preparation of diagnostic reagents and their standardization. We have recently developed a method for the production of alpha-fetoprotein from a human hepatoma cell line. This method, which is suitable for scaling up, allowed us to produce 40 g of alpha-fetoprotein from culture supernatant liquid through a simple purification procedure. We have previously shown this protein to be identical to alpha-fetoprotein produced from other sources. However, because the presence of different glycoforms has been reported in alpha-fetoprotein preparations, both from human sources and from other species, it was important to establish the type and extent of glycosylation of alpha-fetoprotein prepared by our method. By using 1H-NMR spectroscopy we were able to establish that our product contains a single N-linked biantennary, fully sialylated complex-type oligosaccharide, typical of human hepatomas
Monoclonal antibodies recognizing a recombinant portion of human alpha-fetoprotein with antigenic selectivity versus albumin.
No full textDetermination of serum alpha-fetoprotein is useful in the clinical management of liver cancer, but it has not been particularly helpful in the early diagnosis of this disease, since also non-neoplastic liver diseases may result in small increases of its serum concentration. To improve the clinical performance of this assay, we have previously developed an in vitro culture system, in which the expression of alpha-fetoprotein and albumin could be coordinately modulated by thyroid hormone. This system allowed large scale production and purification of native alpha-fetoprotein to be used as reference material. In addition, we synthesized and cloned in a bacterial expression vector a DNA sequence coding of human alpha-fetoprotein amino acid sequence 38-119. This alpha-fetoprotein sequence was chosen since it is the least homologous to albumin, being the amino acid sequence of the two proteins extremely similar with an overall identity of about 38%. Now we have obtained three hybridomas recognizing with high affinity and specificity both the recombinant fragment and native alpha-fetoprotein. These antibodies, which therefore recognize the native protein in the amino acid sequence 38-119, should allow the development of an immunoassay for alpha-fetoprotein with absolute selectivity versus albumin. This might result in more sensitive clinical determinations, avoiding the possibility of cross-reactions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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