bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stable quantitative differences of antigen expression in human melanoma cells isolated by flow cytometric cell sorting
Authors: Lindmo T. , Davies C. , Fodstad Ø. , Morgan A. C. 
Published: February 2007

AbstractThe stability of expression of a membrane antigen on human FME melanoma cells was investigated by means of flow cytometric cell sorting and analysis. The melanomaassociated 250 kd antigen was strongly expressed on all cells, as recognized by binding of the monoclonal antibody 9.2.27. By flow cytometric cell sorting, cells of high and low antigen expression were isolated, and the difference in antigen expression between the two populations was examined as a function of time in culture. Immediately after sorting, the median fluorescence intensities of the two populations differed by a factor of 2.7. After the first few days in culture, much of the range in antigen expression of the parent population was regenerated. However, a lasting difference in antigen expression was established, corresponding to 50% higher density of antigen on the cells sorted for high fluorescence intensity, compared to those sorted for low intensity. After trypsin treatment, which removed the antigen from the cell surface, normal antigen expression was regained after 2‐3 days in culture, with the same difference between the two populations as before the trypsin treatment. The stability of the established difference in antigen expression between the two sorted subpopulations indicates that expression of this antigen is a precisely controlled, heritable characteristic of the FME melanoma cells.
Immortalization of peripheral blood lymphocytes of cats by human T‐cell leukemia virus
Authors: Hoshino H. , Tanaka H. , Shimotohno K. , Miwa M. , Nagai M. , Shimoyama M. , Sugimura T. 
Published: February 2007

AbstractPeripheral blood lymphocytes of domestic cats were co‐cultivated with lethally irradiated MT‐2 cells, which produced human T‐cell leukemia virus type I (HTLV‐I). Two cat lymphoid cell lines, CaL‐l and CaL‐2, established and maintained without exogenously added T‐cell growth factor, were characterized after more than 6 months of cultivation. These cells grew in suspension, had a chromosome number of 38 and lacked cytoplasmic and surface immunoglobulins. CaL‐2 cells formed E‐rosettes. Both cell lines harbored HTLV genomes but not human Alu family sequences, which are highly repetitious in the human genome, suggesting that transfer of human DNA fragments was not necessary for their immortalization or transformation. HTLV antigens were detected in CaL‐l and CaL‐2 cells by indirect immunofluorescence assay. CaL‐l and CaL‐2 cells both expressed viral proteins with apparent molecular weights of 53 kd, 24 kd and 19 kd, and CaL‐2 cells also expressed 28 kd and 20 kd proteins. Reverse transcriptase activity was detected in culture fluid of CaL‐2 cells, but not of CaL‐l cells. CaL‐2 cells but not CaL‐l cells had syncytium‐induced activity. These findings indicated that lymphocytes of cats, especially T lymphocytes, were susceptible to infection with HTLV and to immortalization by HTLV.
Biogenic silica fibre promotes carcinogenesis in mouse skin
Authors: Bhatt T. , Coombs M. , O'Neill C. 
Published: February 2007

AbstractSilica fibres derived from plants are common contaminants of human diet in certain regions of the world where oesophageal cancer reaches extremely high incidences. We show here that one of these types of fibre (derived from Phalaris, canariensis L) promotes the occurrence of tumours in the skin of mice initiated with a polycyclic carcinogen. Three experiments are described. In the first, the grain which bears these fibres was added to the diet. This did not result in any abnormality in any part of the gastrointestinal tract, but there was a significant induction of tumours in the skin around the mouth and nose; these were the areas of the body surface which most frequently came into contact with the grain. In the second experiment, the mice were separated from the grain by an intervening wire gauze barrier; a similar number of tumours appeared on initiated mice treated in this way. In this case, contact now occurred most frequently on the dorsal surface, which was rubbed against the gauze barrier, and it was on this surface that the tumours appeared. No tumours appeared if the grain was removed. In the third experiment, pure fibres were isolated from the surface of the grain and boiled in strong nitric acid so as to remove any organic material. When these acid‐cleaned fibres were applied to the initiated skin with light pressure, they promoted carcinogenesis in the same way as croton oil. In each experiment the majority of tumours produced were benign neoplasms, together with at least one squamous carcinoma. It seems possible that the size and shape of these fibres are the critical properties determining their promoting activity. Their mean diameter is 15 μm, their modal length close to 200 μm, and they are sharply pointed with a tip diameter of 0.5 μm.
Influence of migratory blood cells on the attachment of tumor cells to vascular endothelium
Authors: Starkey J. R. , Liggitt H. D. , Jones W. , Hosick H. L. 
Published: February 2007

AbstractThe purpose of this study was to determine whether the presence of migratory blood cells in association with tumor emboli had the capacity to alter the attachment of tumor cells to vascular endothelium. Highly metastatic RT7‐4bs rat hepatocarcinoma cells were labelled with [125]UdR before being allowed to form mixed cellular spheroids incorporating 1) resident peritoneal macrophages, 2) activated peritoneal macrophages, 3) polymorphonuclear leukocytes, 4) splenic T lymphocytes, or 5) splenic B lymphocytes derived from both normal and tumor‐bearing animals. The presence of polymorphonuclear leukocytes or activated macrophages led to a considerable increase in the number of tumor cells attaching to endothelial cell monolayers in vitro. The presence of T or B lymphocytes from either normal or tumor‐bearing rats was without effect on tumor attachment to endothelium. Increased tumor cell retention in the lungs was evident for mixed spheroids containing tumor cells and polymorphonuclear leukocytes compared to homotypic tumor spheroids composed of tumor cells alone. Furthermore, preinjection of polymorphonuclear leukocytes intravascularly or inoculation of tumor cells as heterotypic spheroids containing polymorphonuclear leukocytes increased lung colony formation over that obtained after inoculation of tumor cells alone. Several simple sugars were tested for their ability to block tumor cell, polymorphonuclear leukocyte or activated macrophage binding to endothelium in vitro. The results indicate that the glycosylated cell surface components mediating tumor cell attachment to endothelium are not identical with those mediating attachment of either polymorphonuclear leukocytes or activated macrophages. Medium conditioned during mixed spheroid formation was without effect on tumor cell attachment to endothelium. We conclude that the presence of some, but not all classes of leukocytes can modulate tumor cell attachment to vascular endothelium, an effect most likely mediated by a mechanism involving direct contact between the leukocytes and the endothelial cell monolayer.
Morphology of peritumoral proteoglycan alterations in the rabbit mesentery invaded by V2 carcinoma cells
Authors: Müller‐Glauser Werner , Haemmerli Gisela , In‐Albon Annemarie , Strauli Peter 
Published: February 2007

AbstractAfter intraperitoneal implantation into Swiss Silver rabbits, V2 rabbit carcinoma cells invade the mesentery where they form nodules of different size and texture: compact (less than 120 μm in diameter), loose (120‐250 ũm) and mixed (above 200 ũm). Together with tumor development, certain changes take place in the loose connective tissue of the mesentery. Application of TEM, together with use of safranin O, has shown that, in areas free of tumor growth, collagen bundles become thick and heavy and proteoglycan density is increased. Concurrently, the number of fibrocytes, now transformed to fibroblasts, increases. Small, compact nodules are surrounded by a concentrically arranged extracellular matrix. Its overall density is similar to that of nodule‐free areas. In the immediate vicinity of large, loose nodules, all constituents of the extracellular matrix disappear. Adjacent connective tissue is partly destroyed but still contains collagen fibers and proteoglycans. These findings suggest the following: (1) The presence of V2 carcinoma cells induces marked alterations in the structured and non‐structured components of the extracellular matrix. (2) These changes are, at the same time, progressive and regressive and the occurrence of one or the other depends on local tumor progression. (3) Progressive alterations may result from an increased activity of fibroblasts. Since degradative effects, on the other hand, are only seen in the immediate vicinity of larger tumor aggregates, it is assumed that a minimal number of tumor cells is essential for destruction of extracellular matrix.
In vivo induction of tumor‐specific immunity by glycolipid extracts of SV40‐transformed cells
Authors: Ansel Sandra , Blangy Daniel 
Published: February 2007

AbstractGlycolipid extracts were prepared from various Syrian golden hamster cell lines, either SV40‐transformed or spontaneously transformed. To detect possible SV40‐TSTA activity of the glycolipid preparations, normal hamsters were inoculated with different glycolipid extracts and were subsequently challenged with an SV40 tumor‐cell line. Significant immunoprotection against SV40 tumor challenge was induced with glycolipids obtained from SV40‐transformed cell lines. This was expressed as complete tumor rejection or as a decrease in tumor growth rate, when compared to controls. No protective effects were induced with glycolipid extracts from spontaneously transformed cells. Results suggest that tumor‐specific glycolipids synthesized in cells transformed by SV40 virus could act as tumor transplantation antigens responsible for specific tumor rejection in syngeneic hosts.
Procoagulant activity of macrophages associated with different murine neoplasms
Authors: Guarini Anna , Acero Raffaella , Alessio Grazia , Donati Maria Benedetta , Semeraro Nicola , Mantovani Alberto 
Published: February 2007

AbstractMononuclear phagocytes, an integral part of the lymphoreticular infiltrate of human and experimental tumors, might contribute to tumor‐associated fibrin deposition through the development of procoagulant activity (PCA). We have investigated PCA of tumor‐associated macrophages (TAM) in 6 transplanted murine tumors in syngeneic hosts; peritoneal macrophages from tumor‐bearing and control animals were studied also, as reference cell populations. PCA was evaluated by a one‐stage clotting assay immediately after preparation and following incubation in the absence and in the presence of endotoxin. TAM from 5 poorly immunogenic tumors (mFS6, MN/MCA1, R 80/44, M109 and MS2) had basal PCA levels comparable to or somewhat lower than those of peritoneal macrophages from the same animals. Similar PCA was found in peritoneal macrophages from both control and tumor‐bearing animals. Unlike peritoneal macrophages, TAM in all instances failed to respond with increased PCA when exposed to endotoxin in vitro. Failure to respond to endotoxin could not be ascribed to contaminating tumor cells or their products, to the presence of suppressive macrophage populations or to the lack of lymphocyte “help”. TAM from a strongly immunogenic, regressing tumor (MSV sarcoma), in contrast to its non‐immunogenic variant, MS2, and to the 4 other tumors mentioned above, expressed high levels of PCA immediately after isolation. The latter did not increase further following in vitro stimulation with endotoxin. When MSV sarcomas were induced in nude mice, TAM showed PCA levels similar to those of the euthymic hosts, suggesting that the procoagulant response was largely independent of T‐cell‐mediated immunity.
Precursor lesions of oesophageal cancer in a low‐risk population in China: Comparison with high‐risk populations
Authors: Crespi M. , Muńoz N. , Grassi A. , Qiong Shen , Jing Wang Kuo , Jien Lin Jing 
Published: February 2007

AbstractAn endoscopic survey was undertaken in Jiaoxian, People's Republic of China, a population at low risk for oesophageal cancer, to determine the prevalence of precancerous lesions of the oesophagus, and this rate was compared with the prevalence observed previously in high‐risk populations in Iran and Linxian, China. The study involved 252 subjects whose exposure to suspected risk factors was determined by a questionnaire and all of whom underwent physical examination and oesophagoscopy, including cytology and biopsy. Chronic oesophagitis, with endoscopic and histologic characteristics similar to those observed in the high‐risk populations of Iran and Linxian, was found in 28% of the study subjects compared to 80% in Iran and 65% in Linxian. Oesophagitis accompanied by atrophy of the epithelium was found in 0.4% compared to 10.5% in Iran and 10.8% in Linxian. No case of dysplasia was diagnosed in Jiaoxian while this condition was diagnosed in 4% of the subjects examined in Iran and in 8% of those in Linxian. The findings suggest that these lesions are in fact precancerous. Vitamin analysis showed that riboflavin deficiency was widespread in Jiaoxian, as in Iran and Linxian, but was more severe in Linxian than in Jiaoxian. No significant difference was found in the mean levels of retinol, beta‐carotene and zinc between the two populations.
Molecular cloning and analysis of a new variant of human T‐cell leukemia virus (HTLV‐Ib) from an African patient with adult T‐cell leukemia‐lymphoma
Authors: Hahn Beatrice H. , Shaw George M. , Popovic Mikulas , Monico Anita Lo , Gallo Robert C. , Wong‐Staal Flossie 
Published: February 2007

AbstractWe report the identification and characterization of a new variant of HTLV‐I in an African patient with adult T‐cell leukemia/lymphoma (ATL). Proviral sequences were detected by Southern blot analysis in three T‐cell lines established from this patient's peripheral blood lymphocytes (PBL) and lymph‐node cells. We molecularly cloned and analyzed proviruses from two of these cell lines, one established by direct culture of PBL and one established by co‐cultivation of PBL with cord‐blood T cells. These two HTLV clones contained full‐length proviruses which were identical to each other in 44 out of 44 restriction enzyme sites. They were closely related to, but distinct from, the prototype HTLV‐I, having divergence in their envelope and 5′ pX regions and therefore represented a new variant of HTLV‐I. We designated it as HTLV‐Ib. Despite the genomic differences, however, HTLV‐Ib retained its tropism for OKT4+ lymphocytes as well as its ability to initiate and maintain transformation of these cells. The finding of a variant of HTLV‐I in this African ATL patient, along with the results of recent seroepidemiological studies, extends to the African continent the prevalence of HTLV‐I associated malignancy previously identified in the Caribbean and Japan.
Detection of an interferon antagonist, sarcolectin, in human sarcomas and muscles
Authors: Jiang Pan Hong , Chany‐Fournier Françoise , Sarragne Madeleine , Grégoire Anne , Chany Charles 
Published: February 2007

AbstractIn a variety of human sarcomas we detected the presence of a sarcolectin which reversed an established antiviral protection induced by interferon (IFN). For the same protein concentration, this biological activity was significantly increased when compared to that of normal muscles. All the biological characteristics were comparable to those of a sarcolectin found in hamster tissues; namely the capacity to agglutinate cells and its inhibition by specific sugars, migration in sodium dodecyl sulfate gel, and pepsin, heat and sodium dodecyl sulfate stability. Except for its anti‐IFN function and cell agglutinating activity, the biological significances of this sarcolectin is presently poorly understood.
Heat‐shock proteins produced by two human melanoma cell lines: Absence of correlation with thermosensitivity
Authors: Ferrini Umberto , Falcioni Rita , Delpino Andrea , Cavaliere Renato , Zupi Gabriella , Natali Pier Giorgio 
Published: February 2007

AbstractTwo human melanoma cell lines, extremely different in their thermal sensitivity, were pulse‐labelled with (35S)‐methionine after 60 min of exposure at 42° C. For both cell lines, fractionation of the intrinsically labelled proteins by polyacrylamide gel electrophoresis (PAGE) showed increased labelling of a polypeptide band of Mr 72,000, along with a slight reduction of overall protein synthesis. By two‐dimensional electrophoresis, the Mr 72,000 band resolved into multiple pattern components of the same size but differing in isoelectric points. The absence of qualitative and quantitative differences between the two melanoma cell lines indicates that the different thermal sensitivities are unrelated to their ability to express the heat‐shock proteins.
A human nucleolar antigen (pp90) associated with cell growth and its induction by epstein‐barr virus and human cytomegalovirus
Authors: Kamata Tohru , Ohtsuka Masahiro , Watanabe Yasushi 
Published: February 2007

AbstractImmunofluorescent staining of HeLa cells with rabbit antiserum raised against isolated HeLa cell nucleoli showed bright nucleolar fluorescence. Immunoprecipitation of nuclear extracts obtained from HeLa cells labelled with 35S‐methionine or 32P‐orthophosphate followed by gel electrophoresis of the precipitate revealed a major band of 90 kd. This antigen, called pp90, was judged to be responsible for the nucleolar fluorescence. Serine residues were predominantly phosphorylated in pp90. Similar nucleolar fluorescence was observed commonly in human cells derived from malignant tumors including acute lymphatic leukemia, adult T‐cell leukemia, hepatitis B virus‐associated hepatoma, adenocarcinoma, and in 5 lymphoid cells derived from Burkitt lymphoma but not in normal human lymphocytes or liver cells. In immunoprecipitation, 32P‐labelled pp90 was commonly detected as the major component in all of those cells which showed nucleolar fluorescence. Resting human embryo lung (HEL) cells were negative for both nucleolar fluorescence and pp90 in immunoprecipitation, but turned positive when stimulated to grow, suggesting the involvement of pp90 in cell growth. Antigen pp90 was also induced in human lymphocytes and HEL cells by infection with Epstein‐Barr virus in human cytomegalovirus, respectively, which are known to induce cell DNA synthesis in early stages of infection. A crossreacting nucleolar antigen was detected in 2 monkey cells but not in 3 rodent cells tested.
Oral contraceptives containing chlormadinone acetate and cancer incidence at selected sites in the German Democratic Republic ‐ A correlation analysis
Authors: Nischan P. , Ebeling K. 
Published: February 2007

AbstractThe use of oral contraceptives containing chlormadinone acetate in 1972 by women of 13 districts (out of 15) of the GDR has been related to the incidence of cancer of breast, corpus uteri, and ovary during the period 1961 to 1980. Cancer incidence was represented by cohort parameters showing the risk of the cohorts in relation to each other. No statistically significant association between the two events was noted. Although not significant, our data are consistent with an elevated relative risk for breast cancer of 1.3 and a decreased risk for ovarian cancer of 0.5.
Dopamine receptors in a human colonic cancer cell line (HT29). Some receptor‐related biological effects of dopamine
Authors: Scemama J. L. , Ruellan C. , Clerc P. , Clemente F. , Ribet A. 
Published: February 2007

AbstractThe presence of dopamine receptors in normal colonic cells has been postulated from physiological studies. The existence of such receptors in human colonic tumor cells and their role in tumor progression are still unknown. The aim of the present work was to characterize the dopaminergic receptors in a human colonic adenocarcinoma cell line (HT29) and to evaluate the effect of dopamine on cAMP, protein and DNA synthesis. The binding characteristics of 3H‐dopamine on the tumor cells were rapid, reversible, specific, saturable and stereospecific. The first site characterized corresponds to a D3 subtype: KD 3.09 nM, insensitive to sulpiride, unrelated to adenylate cyclase. Competitive inhibitions of 3H‐dopamine binding by different drugs showed the existence of a second binding site, D1, with an apparent affinity for dopamine of 6,700 nM. The rank order of potency of inhibitors of 3H‐dopamine binding was: haloperidol > dopamine > cis flupenthixol > (+) butaclamol > (−) butaclamol > trans flupenthixol > isoproterenol > clonidine > prazosin. D3 binding sites are modulated with age, Bmax was 116 fmol/106 cells on the 5th day and decreased to 8.2 fmol/106 cells on the 15th day of culture. Cell culture in serum‐deprived medium allowed an increase in the number of high‐affinity receptor sites. D1 sites are coupled to adenylate cyclase as shown by a dose‐dependent cAMP accumulation from 10−8 M to 10−5 M dopamine concentrations. Interacting with D1 sites, dopamine evokes an increase in protein synthesis with no modification of 3H thymidine incorporation. The present results indicate that the human colonic cancer cell line HT29 exhibits dopamine receptors and that stimulation may induce metabolic modifications in the tumor cells.
Immune rejection mechanisms in murine leukemia. I. Timing of tumor cell rejection process relative to the development of humoral and cell‐mediated cytotoxic immune responses
Authors: Ciavarra Richard P. , Terres Geronimo 
Published: February 2007

AbstractStudies were undertaken to investigate the relationship between cell‐mediated and humoral immune responses in the rejection of LI210/MTX‐Rev (LR) leukemia cells in CD2F1 mice. The anti‐LR antibody (humoral) response was defined by both its cytotoxic antibody titer and isotype composition, assessed by a complement‐dependent cytotoxicity assay and radioimmune assay, respectively. The cytotoxic thymus (T)‐derived lymphocyte response in the spleen was quantitated by 125I release by 125I‐IUdR‐labelled target cells. Analysis of the sera of tumor‐bearing mice indicated that the LR leukemia cells elicited a wide spectrum of anti‐tumor antibody isotypes. In mice that mounted a rejection response, the IgM anti‐LR response was transient, while in those that did not, the IgM response persisted. Antibody titers for all isotypes remained low until the onset of LR rejection. At that time, high titers of IgG anti‐LR antibodies, predominantly of the IgG2a subclass, were detected in sera of tumor‐free mice. Thus, the LR rejection response coincided best with the appearance of high titers of IgG2a anti‐LR antibodies. A single i.p. injection of viable LR cells elicited a potent cell‐mediated immune response; neither the appearance nor the magnitude of the cell‐mediated immune response as measured in the spleen correlated well with the onset or the strength of the LR rejection response in the peritoneal cavity. The LR peritoneal cell population grew unabated in the presence of an intense spleen cell‐mediated immune response, and the rejection process began at a time when little cellular immunity could be detected. These results suggest that in the rejection response IgM antibodies contribute little, if any, to the process, and the role of cytotoxic T lymphocytes is questionable (uncertain). The rejection of LR cells appears to be primarily mediated by IgG2a antibodies.