bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of tumorigenic potential in isologous hybrid clones of chinese hamster cells
Authors: Blanchard M. G. , Barski G. , Léon B. , Hémon D.
Published: February 2007

Karyotypes and phenotypic characteristics of several clones, developed from a wild population of somatic hybrids obtained by crossing two Chinese Hamster cell lines, were analysed in detail. The crossed cell lines were: (1) the DC‐3F, sensitive to Actinomycin D (AD) and highly tumorigenic when checked by inoculation into the Syrian Hamster cheek pouch, (2) the DC‐3F/AD/Aza, resistant to AD and non tumorigenic. In the 6 clonal lines and their 3 derivatives, obtained secondarily from tumors, the resistance to AD was mostly associated with low or even entirely non‐expressed tumorigenic properties, whereas sensitivity to the toxic action of AD was, as a rule, linked with high malignancy. For all the studied clonal and derived lines a general tendency for chromosomal deletion from the “ideal”, complete integration of the two parental karyotypes, was observed. This deletion was frequently, but not always, more accentuated following passage through the animal and production of tumors. The relatively stable aspect of the Chinese Hamster karyotype, with most of the chromosomes easily identifiable, permitted a detailed analysis of the frequency of presence or deletion in the 8 pairs and groups of autosomes, the × and the M1 abnormal marker chromosomes. This analysis has shown that, in general, a preferential deletion occurred in the chromosomes Nos. 2, 4, 5, X, and M1. However, no link existed between the frequency of these individualized chromosomal deletions and either the malignancy or the resistance to AD of the hybrid clones.
The effect of splenectomy on fibrosarcoma “metastases” in lungs of mice
Authors: Milas Luka , Mujagic Hamza
Published: February 2007

Cells of a methylcholanthrene‐induced fibrosarcoma, injected intravenously into syngeneic C57Bl mice, generated tumour nodules (“metastases”) in the lungs. The number of tumour nodules was reduced in recipients whose spleens had been previously removed. This effect of splenectomy was specific (thymectomy did not affect the number of pulmonary metastases), and was greater if fewer tumour cells were injected. It was also observed that active immunization against the fibrosarcoma caused stronger inhibition of pulmonary metastases in splenectomized than in sham‐operated mice.
EBV infections in Brazil. I. Occurrence in normal persons, in lymphomas and in leukemias
Authors: Carvalho R. P. S. , Evans A. S. , Frost P. , Dalldorf G. , Camargo M. E. , Jamra M.
Published: February 2007

Comparisons of IF antibody tests with EB3 and Jijoye cells indicated an overall agreement of 80%. However, the Jijoye line results in a higher frequency of positives at 1:10, a higher frequency of elevated titers of 1:160 or more, and a higher geometric mean antibody titer than with EB3 cells. At titers of 1:320 or higher the results with the two lines were quite comparable and are taken as elevated. Antibody to EBV is widely present in sera from Brazilian residents. Infection occurs early in life in the lower socioeconomic groups. In the middle and upper economic groups over 50% have antibody by age 12. In 69 lymphoma cases tested, all except one (Hodgkin's disease) had EBV antibody demonstrable at 1:10 titer or higher. Elevated EBVantibody titers at levels of 1:320 or higher were found in 41.9% of sera from the 43 cases of Hodgkin's disease having antibody and 4 of 8 cases of Burkitt's lymphoma; the geometric mean titers (GMT) were 1:173.4 and 1:246.8 respectively as compared to 1:51.4 in controls. In 13 cases of lymphosarcoma 23.1% had titers of 1:320 or higher and the GMT was 1:104.4. ERV antibody titer was present but not elevated in four cases of reticulosarcoma. Of 43 leukemia patients, one lacked EBV antibody at 1:10. Of the 42 possessing antibody, 31.0% had elevated titers with a GMT of 1:142.5. The highest titers occurred in mute myeloid leukemia.
Study of the cellular proliferation kinetics of friend leukemia
Authors: Smadja‐Joffe Florence , Jasmin C. , Malaise E. P. , Bournoutian Catherine
Published: February 2007

We have studied the kinetic parameters of the polycythemic variety of Friend leukemia using DBA2 mice inoculated with the virus. Proliferation was mainly observed in the erythroblasts of the spleen. The mean duration of the mitotic cycle is 7.6 h and the majority of erythroblasts are in active stages of the cell cycle. The proliferation rate is unaffected even during the hours preceding death. The multiplication of erythroblasts in the spleen results in three different phenomena: 1/3 of the erythroblasts produce short‐lived erythrocytes; a very small fraction (1/20) of the proliferation accounts for the slow growth of the spleen and the progressive invasion of the liver and the blood; 2/3 disappear, and this loss is apparently due to massive splenic cellular death.
Fractionation of plasma membrane‐associated tumour‐specific antigen from an aminoazo dye‐induced rat hepatoma
Authors: Baldwin R. W. , Harris J. R. , Price M. R.
Published: February 2007

Tumour‐specific antigens from an aminoazo dye‐induced rat hepatoma were liberated in a soluble form following limited papain digestion of tumour cell membrane preparations. Fractionation of the soluble extract by DEAE‐cellulose chromatography, gradient centrifugation and preparative electrophoresis yielded a major antigenic fraction, with an approximate molecular weight of 55,000, together with a range of other minor antigenic components of larger molecular weight. All preparations retained the capacity to inhibit the reaction of antibody in tumour‐immune sera with the plasma membrane of viable hepatoma target cells in the indirect immunofluorescence test. It is considered that the defined antigen fractions isolated provide material suitable for analysing the nature of tumour antigen expression in chemical carcinogenesis and for evaluating the involvement of antigen‐antibody interaction in tumour immunity.
Possible role of 6‐hydroxymethylbenzo[a]pyrene as a proximate carcinogen of benzo[a]pyrene and 6‐methylbenzo[a]pyrene
Authors: Flesher James W. , Sydnor Katherine L.
Published: February 2007

Benzo[a]pyrene (B[a]P) and 6‐methylbenzo[a]pyrene ( 6‐MeB[a]P) are metabolized by fortified rat‐liver homogenates to a number of metabolites including one which is indistinguishable from 6‐hydroxymethylbenzo[a]pyrene (6–OHMeB[a]P) by either thin‐layer chromatography or ultra‐violet absorption spectra. This compound is a potent carcinogen when administered by subcutaneous injection to rats. These observations are in accord with the hypothesis that methylation or hydroxymethylation is one of the first steps in metabolic activation of carcinogenic polycyclic hydrocarbons.
Biochemical correlation of oncogenesis with ontogenesis
Authors: Wu Chung
Published: February 2007

Results on enzyme induction in rat liver and kidney tumors have shown a striking resemblance between the tumors and the perinatal liver and kidney, on the one hand, and a sharp contrast between the tumors and the adult liver and kidney, on the other. Studies on isozyme distribution give similar results. Abnormalities in the responsiveness of enzymes to metabolic modulations and in the induction‐repression of isozymes reflect aberrations in the regulatory genes of the tumors. Since the liver and kidney tumors have originated from the adult liver and kidney, respectively, but show biochemical properties akin to those of the perinatal liver and kidney, it seems that during oncogenesis certain regulatory genes must have been so altered that the cell reacquires the control mechanisms prevailing in an early period of the life of the organism. Hence, a reversion of some of the regulatory apparatus in the cancer cell to that in the perinatal stage of development has taken place. This reversion is considered an essential mechanism in carcinogenesis.
Comparison of some of the biological properties of friend virus and its pseudotypes
Authors: Dawson Peter J. , Fieldsteel A. Howard
Published: February 2007

The properties of the Moloney and Graffi pseudotypes of Friend virus have been compared with those of our original strain of Friend virus. Qualitatively the pathologic effects of the three viruses were indistinguishable. The spleens of mice inoculated with each of the three viruses appeared to have a similarly low potential for the initiation of transplantable tumors in BALB/c mice. Both pseudotypes were highly age dependent when first isolated, although the Moloney pseudotype lost this property after the sixth passage in newborn BALB/c mice. Compared with our original Friend virus, there were marked differences between the host ranges of both pseudotypes. None of these viruses induced Friend disease in C57BL/6 mice. However, preparations of both pseudotypes and of the lymphatic leukemia viruses used as helpers readily induced lymphatic leukemia in this strain, indicating that susceptibility to the helper virus is not the only factor governing host range.
Cellular localization of an Epstein‐Barr virus (EBV)‐associated complement‐fixing antigen in producer and non‐producer lymphoblastoid cell lines
Authors: Reedman Beverley M. , Klein George
Published: February 2007

Anti‐complement immunofluorescence (ACIF) was used to study the complementfixing antigens of human lymphoblastoid cell lines. These cell lines carry the Epstein‐Barr virus (EBV) genome although only producer cultures synthetize EBV‐specific antigens (virus capsid antigen, VCA and early antigen, EA) detectable by direct and indirect immunofluorescence, usually in less than 5% of the cells. The ACIF test revealed an antigen localized in the nucleus of the lymphoblastoid cells. In contrast to EA and VCA, this antigen was present in over 90% of the cells of both producer and non‐producer cultures. The antigen was shown to be specific for EBV by comparing the reactions of 52 sera in the ACIF test. Sera giving the nuclear reaction contained antibodies to VCA, EA or antigens detectable by complement fixation tests on cell extracts, but sera without EBV antibodies failed to give the reaction. Weak, equivocal or discordant reactions occurred with six sera with low titres in VCA, EA or complement fixation tests. Cell lines derived by transformation of human and primate lymphocytes by EBV gave the nuclear reaction. Control cells with no known association with EBV were non‐reactive. These included foetal lymphocytes transformed by phytohaemagglutinin, cell lines derived from breast cancer, glioma, normal glia, pleuritis maligna and myeloma, and two marmoset lymphoid lines carrying Herpesvirus saimiri (HVS). In preliminary experiments, the ACIF test was used as a tool to trace the EBV genome at the cellular level. Cells from two Burkitt lymphoma biopsies, one tested after biopsy and one after passaging in nude mice, contained an EBV‐specific antigen. Three clones of cells derived from hybrids of mouse somatic cells and a human lymphoblastoid cell line also contained such an antigen, but the number of reactive cells varied from clone to clone. A fourth clone was non‐reactive.
Auto‐immunization with acute leukemia cells: Demonstration of increased lymphocyte responsiveness
Authors: Gutterman J. U. , Mavligit G. , McCredie K. B. , Freireich E. J. , Hersh E. M.
Published: February 2007

Nine patients with adult acute leukemia were autoimmunized with 108 and/or 106 non‐irradiated leukemia cells during remission. Six of nine receiving 108 cells demonstrated a 100% or greater increase in in vivo lymphocyte blastogenic response to their own leukemia cells measured 7 days after immunization. In four responders, increased blastogenesis was noted only in autologous serum, but not in allogeneic serum. Only one of four demonstrated increased lymphocyte blastogenic response in autologous serum after immunization with 106 cells. The increased immune response was always accompanied by significantly increased blastogenic response to phytohemagglutinin (PHA) and/or Streptolysin‐O (SLO). Three patients studied 28–42 days following immunization showed a persistent increase in lymphocyte blastogenic response to leukemia cells, but the response to PHA and SLO had returned to pre‐immunization levels.
Immunoradioautography test for alpha‐fetoprotein in the differential diagnosis of germinogenic tumors of the testis and in the evaluation of effectiveness of their treatment
Authors: Elgort D. A. , Abelev G. I. , Levina D. M. , Marienbach E. V. , Martochkina G. A. , Laskina A. V. , Solovjeva E. A.
Published: February 2007

The diagnostic value of detecting AFP with the indirect immunoradioautography (IR) method has been investigated for teratoblastomas of the testis in adult patients. It is shown that the IR method permits an approximately two‐fold increase in the number of serologically diagnosed teratoblastomas, as compared with the standard gelprecipitation method. The results for patients with primary testicular teratoblastomas were 19 AFP‐positives in a group of 21 (90.5%). The diagnostic specificity of the test has been lowered insignificantly with the high‐sensitivity method: only 8 AFP‐positive cases were found in a control group of 215 patients, and all the seropositives suffered from tumors of the gastro‐intestinal tract with metastases to the liver. Application of the IR method has greatly increased the possibility of following the course of disease and effectiveness of treatment by the AFP test; in a number of cases it has also permitted a more accurate diagnosis of primary tumor, when metastases are present.
Studies on the ultrastructure of concanavalin a receptor sites at the surface of normal cells and cells transformed by oncogenic viruses
Authors: Torpier G. , Montagnier L.
Published: February 2007

The distribution of receptor sites for Concanavalin A at the surface of hamster fibroblasts BHK 21/13 transformed by RNA or DNA oncogenic viruses, has been studied at the ultrastructural level by the Concanavalin‐peroxydase method, in connexion with the agglutinability of these cells. The product of the lectin‐bound peroxydase activity has the same thickness in all clones studied. In some transformed clones, the observed reaction is more irregularly distributed than in the original untransformed clone. These changes are however not always accompanied by changes of agglutinability. Moreover, such an irregular distribution has also been found in normal cells from other species. It is concluded that the surface alteration detected by the peroxydase method cannot be considered at the present time as a general transformation character.
Specific neutralizing antibodies in Epstein‐Barr virus associated diseases
Authors: Rocchi G. , Hewetson J. , Henle W.
Published: February 2007

The results of Epstein‐Barr virus (EBV) neutralization tests on 650 sera from patients with EBV‐associated diseases and controls were compared with the titers of antibodies to EB viral capsid antigens (anti‐VCA) and to EBV‐induced early antigens (anti‐EA). All anti‐VCA negative sera failed to neutralize EBV. Among 546 anti‐VCA positive sera, only eight yielded negative results in neutralization tests. Four of these came from patients in the early acute phase of infectious mononucleosis who subsequently developed neutralizing antibodies. The ratios between neutralizing and anti‐VCA titers varied over a wide range indicating that different antibodies are involved in the two tests. In line with the regular presence of mostly elevated anti‐VCA titers, the geometric mean neutralizing titers in Burkitt's lymphoma and nasopharyngeal carcinoma were also higher (5‐ to 7‐fold) than in appropriate controls. In Hodgkin's disease, an over‐representation of high neutralizing as well as anti‐VCA titers was noted, although some patients had neither of these antibodies. All patients with infectious mononucleosis developed neutralizing antibodies with a geometric mean ultimately matching that of controls whereas in the early acute phase it was lower than in the controls. In contrast, the geometric mean anti‐VCA titer in the early acute phase was higher than in controls and then declined in convalescence toward the control value. There was no evident relationship between neutralizing and anti‐EA activities whether directed against the D or the R component of the EA complex.
Increase in viral antigen in individual polyoma‐virus‐infected mouse kidney cells as studied by quantitative immunofluorescence
Authors: Levin A. , Killander D. , Nordenskjöld B.
Published: February 2007

Polyoma‐virus infection of mouse kidney cells in vitro was studied on the single cell level by quantitative cytochemical techniques. Cells were fixed in acetone at different times after infection and reacted with fluorescein‐conjugated mouse anti‐polyoma‐virus immune serum. Visual determinations were made as to whether the cells were fluorescent (“positive”) or not (“negative”). Visually the fluorescence was located in the nuclei in the “positive” cells. The fluorescence intensities of individual cell nuclei were then measured in a microspectrofluorimeter. Nuclei with considerable fluorescence intensity were noted to be visually “positive”. However, nuclei of cells which were usually judged to be “doubtful” could also be shown to have measurably greater fluorescence intensity than control non‐infected cells. Increase in fluorescence values were noted 6‐11 h after infection whereas hemagglutination tests did not become positive until 10‐20 h later. With increasing time post infection, the fraction of fluorescence positive cells increased both as judged visually and as determined by the microfluorimeter. The variation in fluorescence intensities among different nuclei also increased and, 48‐50 h after infection, the ratio between the highest and the lowest fluorescence values of positive cells was about 10:1. Higher fluorescence intensities were found in cytoplasms of cells with “positive” nuclei than in cells with “negative” nuclei. The cytoplasmic and nuclear fluorescence intensities correlated well in cells with “positive nuclei”. The polyoma‐virus infection‐induced stimulation of DNA synthesis was demonstrated by increased incorporation of 3H‐thymidine and by increased amounts of DNA in the cells as measured by Feulgen microspectrophotometry. The amount of DNase‐resistant DNA (i.e. viral DNA) correlated well with the intensity of immunofluorescence measured on the same individual nuclei of infected cells. This was taken as one indication that viral antigens can be measured on the single cell level by quantitative immunofluorimetry.
Depression of complement activity in three strains of mice after tumor transfer
Authors: Drake Walter P. , Legendre Stephen M. , Mardiney Michael R.
Published: February 2007

Both immune adherence and hemolytic complement activity were measured as a function of time after either intraperitoneal or subcutaneous injection of six transplantable tumors carried in three strains of mice. There was a lack of correlation between complement activity measured by these assays in accord with other studies on human cancer patients. The data indicate that host complement activity was depressed in all cases following tumor transfer and suggest that the serotherapy of murine tumors using passively administered anti‐tumor serum may be compromised by host complement insufficient to mediate tumor cytolysis in vivo.
A rapid destructive effect of the Schmidt‐Ruppin strain of rous sarcoma virus on transformed rat cell lines
Authors: Reinisch Carol L. , Bang Frederik B.
Published: February 2007

A cytopathic effect was induced by the Schmidt‐Ruppin strain of Rous sarcoma virus (RSV‐SR) in five of nine rat tumor cell lines tested in vitro. The cells showed irreversible cytopathic change as early as 24‐48 h after infection. Of the leukemogenic and tumorigenic viral agents tested, only RSV‐SR induced the rapid Rous cytopathic effect. Virus was recovered 8 days after inoculation of the tumor cell lines XC and M41. The effect was neutralized by specific anti‐RSV‐SR antiserum. Correlation between oncogenicity of the rat tumor lines in the syngeneic host and their susceptibility to RSV‐SR was incomplete.
Inheritance of susceptibility to friend mouse leukemia virus. XI. Genetic control of late splenomegaly
Authors: Odaka Takeshi
Published: February 2007

Genetic control of splenomegaly which occurs at a late stage of Friend leukemia virus infection was studied in hybrid mice between DDD‐Fvr and C57BL/6. It was demonstrated that this late splenomegaly was mainly controlled by a single autosomal locus with the dominant allele for resistance. This locus may be idential with or genetically linked with the locus which controls the level of virus multiplication at an early stage of infection. Considered together with previous findings, splenomegaly induced by Friend leukemia virus in mice is classified into two types, early and late, both being controlled by two separate gene loci.
Isolation and characterization of a primate sarcoma virus: Mechanism of rescue
Authors: Scolnick Edward M. , Parks Wade P.
Published: February 2007

A clonal isolate of an RNA‐containing sarcoma virus derived from a spontaneous woolly monkey fibrosarcoma has been obtained. The woolly sarcoma virus transformed cells do not spontaneously yield infectious virus but do contain the woolly gs antigen. The primate sarcoma virus can be rescued with comparable efficiency by superinfection with either murine or primate helper type‐C viruses. During rescue with murine helper type‐C virus, the intracellular level of woolly monkey gs antigen does not rise in proportion to the production of helper gs antigen, or in proportion to the production of transmissible focus‐forming virus. The results suggest that the mechanism of rescue may simply involve an assembly of sarcoma components into an infectious particle during the production of the helper type‐C virus.
Reversion in hybrids between SV40‐transformed hamster and mouse cells
Authors: Wiblin C. N. , Macpherson I.
Published: February 2007

The expression of the transformed phenotype was studied in segregants from a hybrid cell line resulting from the fusion of SV40‐transformed BHK21 Syrian hamster cells (thioguanine resistant) and 3T3 mouse cells (bromodeoxyuridine resistant). Since the hamster cell parent was sensitive to bromodeoxyuridine, segregants lacking chromosomes could be obtained by “back‐selection” in this drug. These segregants retained transformed characteristics, despite substantial loss of hamster chromosomes. Selected segregants were treated further with cytotoxic antibody raised against the hamster parent. The majority of the segregants isolated retained all transformed characteristics, even when the hamster chromosome complement was greatly reduced. Some derivatives showed properties intermediate between a transformed and an untransformed state. Two revertant clones were also isolated which lacked transformed characteristics and contained no metacentric (hamster) chromosomes. Unlike the other segregants, no SV40 virus could be recovered from these cells. The implications of these results with respect to the integrated status of transforming SV40 genomes are discussed.
Aggregation of feline lymphoma cells by hyaluronic acid
Authors: Wasteson Åke , Westermark Bengt , Lindahl Ulf , Pontén Jan
Published: February 2007

Addition of media from cultured human sarcoma or glioma cells to cultures of suspended feline lymphoma cells (established line FL 74) induced visible aggregation of the lymphoma cells within a few minutes. A number of other normal and malignant cells, including a series of human lymphoid cells, failed to aggregate under identical conditions. The aggregation process showed no temperature dependence, within a range of 4° C to 37° C, and did not require divalent metal ions. The cell‐aggregating factor was heat‐stable and resistant to digestion with trypsin. It was identified as hyaluronic acid on the basis of its macromolecular and polyelectrolyte properties in conjunction with its susceptibility to various enzymes. A standard preparation of hyaluronic acid induced aggregation of suspended FL 74 cells at concentrations of 30 ng /ml or more. Chondroitin sulphate, chondroitin sulphate proteoglycan, dermatan sulphate, heparan sulphate and heparin did not aggregate the cells, nor did partially depolymerized hyaluronic acid. Pretreatment of the FL 74 target cells with trypsin abolished their clumping ability, implying the presence of a trypsin‐sensitive receptor at the cell surface. Trypsinized and washed cells regained their aggregation properties with hyaluronic acid within a 24 h period in continued culture. The interaction of hyaluronic acid with its receptor was studied by inhibition experiments, in which FL 74 cells were subjected to hyaluronic acid after preincubation with various oligosaccharides. Tetra‐ and hexasaccharides, derived from either hyaluronic acid or chondroitin sulphate, were able to prevent aggregation of the cells by polymeric hyaluronic acid.
Regression of polyoma tumor metastasis by combined unblocking and bcg treatment‐correlation with induced alterations in tumor immunity status
Authors: Bansal S. C. , Sjögren Hans O.
Published: February 2007

Immunotherapy, in the form of inoculations of “unblocking” antitumor sera alone or combined with BCG and splenectomy, was tried in a metastasis model in animals. W/Fu rats were exposed to progressively growing polyoma tumor isografts which were subsequently excised, and then rechallenged with an isograft of the same tumor as a “metastasis”. The immunological manipulation was initiated at the time of rechallenge and, although it was not capable of preventing tumor outgrowth, it caused a complete regression of the outgrowing tumor nodules within a few weeks in 7/7 and 5/16 rats in two different experiments. An attempt was also made to inhibit well‐established spontaneous tumor metastasis to the lung by repeated inoculations of unblocking antitumor serum. Prolonged survival was obtained in four out of nine rats and one of these animals was free of tumor when killed after 4 months. The spread of the tumor to various organs was significantly restricted by the therapy, indicating partially inhibited tumor growth. An attempt was made to establish correlations between inhibition of tumor growth in vivo and certain alterations in the antitumor immunity as analyzed by in vitro techniques. Disappearance of serum blocking activity and appearance of rat complement‐dependent cytotoxicity in serum was seen in all rats with regressing tumors but not in the other animals, although they had received the same treatment. The lymphocyte cytotoxicity was increased to about the same extent in regressor and progressor rats.
Cell‐mediated immunity and blocking factors in patients with tumours of the central nervous system
Authors: Kumar S. , Taylor G. , Steward J. K. , Waghe M. A. , Morris‐Jones P.
Published: February 2007

Lymphocytotoxicity studies were carried out in both the autochthonous and allogeneic situations in nine astrocytomas, seven medulloblastomas and two ependy‐momas. Tumour type‐specific lymphocytotoxicity was demonstrated. The degree of lymphocyte‐mediated tumour‐cell killing did not decrease with the duration of apparent clinical cure. Higher degrees of tumour‐cell killing were found in the autochthonous as compared with the allogeneic combinations. Blocking factor was demonstrated in only three patients.
In vitro cytotoxicity and in vivo tumor enhancement induced by mouse spleen cells autosensitized in vitro
Authors: Ilfeld David , Carnaud Claude , Cohen Irun R. , Trainin Nathan
Published: February 2007

The immuno‐reactivity of C57BL mouse spleen cells previously sensitized in vitro against syngeneic fibroblasts or syngeneic 3LL Lewis tumor cells was investigated. The sensitized spleen cells were assayed in vitro to test their cytotoxicity against the 3LL tumor cells. In addition, spleen cells autosensitized against syngeneic fibroblasts were mixed with 3LL tumor cells and injected into syngeneic recipient mice in order to ascertain their influence on tumor growth. The in vitro assay indicated that lymphoid cells specifically sensitized against either fibroblasts or tumor cells were equally cytotoxic against the 3LL target cells. On the other hand, in the in vivo experiments lymphoid cells sensitized against syngeneic fibroblasts promoted the growth of the 3LL tumor. An attempt to explain the underlying mechanisms involved in the paradoxical behavior of autosensitized lymphocytes is reported herein.
Interferon and cell division. VIII. Effect of interferon on macromolecular synthesis in L1210 cells in vitro
Authors: Brouty‐Boyé D. , Macieira‐Coelho A. , Fiszman M. , Gresser I.
Published: February 2007

Interferon inhibits multiplication of murine leukemia L1210 cells and the effect is evident 18 h after subcultivation. At this time a significant decrease in the synthesis of total RNA and protein was observed in interferon‐treated cultures compared to control cultures. Likewise, the formation of polyribosomes was inhibited in interferon‐treated cultures although no effect was observed on the formation of the ribosomal subunits. As control cells and interferon‐treated cells continued to multiply and the cultures attained cell density saturation, the differences in macromolecular synthesis and polyribosome formation between the cultures became less marked. Confidence that interferon itself was responsible for the effects observed stemmed from the use of highly purified interferon preparations and the availability, as a cell control, of a subline of L1210 cells resistant to interferon action. The possibility that a single mechanism of action is common to the antiviral effect of interferon and its effect on cell division is discussed.
High level of alpha‐fetoprotein in sera of adult mice
Authors: Pihko Helena , Ruoslahti Erkki
Published: February 2007

Mouse a‐fetoprotein (AFP) was purified by making use of its immunological cross‐reaction with rabbit AFP. A radioimmunoassay, developed for mouse AFP, was used to measure AFP concentrations in the sera of adult mice of different inbred strains. The level of adult mouse AFP was found to be 30–350 ng/ml, which is about 10 times higher than has been reported for humans and rats. An association seems to exist between the high basal level of AFP and the remarkably high incidence of spontaneous hepatomas in mice.
Nasopharyngeal carcinoma. IV. Evolution of complement‐fixing antibodies during the course of the disease
Authors: De‐Thé Guy , Sohier Roger , Ho John H. C. , Freund Robert
Published: February 2007

Sequential sera from 37 patients with nasopharyngeal carcinoma (NPC), with either controlled or uncontrolled tumours after radiotherapy, were studied for complement‐fixing (CF) antibodies against a soluble antigen extracted from the QIMR‐WIL lymphoblastoid line. When compared with results obtained previously with the same antigen on sequential Burkitt's lymphoma (BL) sera, the NPC sera exhibited (1) approximately ten‐fold higher CF antibody titres than the BL sera; (2) an overall stability of CF titres in the uncontrolled tumour groups contrasting with the situation in BL; (3) a two‐ to four‐fold decrease in CF titres in the controlled tumour groups; (4) similar CF titres in patients at stage I or IV of the disease. The above suggests an active and long‐standing EBV infection before and during the development of the clinical NPC disease.
The deficient density‐dependent growth control of human malignant glioma cells and virus‐transformed glia‐like cells in culture
Authors: Westermark Bengt
Published: February 2007

The density‐dependent growth control of eight established human glioma lines and virus‐transformed human glia‐like cells has been investigated. All neoplastic lines reached higher terminal cell densities than the corresponding normal glia‐like cells. A marked decrease in proliferation rate occurred at high cell densities which could not be explained by medium depletion or accumulation of toxic substances. An absolute resting phase was not reached by the neoplastic cells; a considerable residual DNA synthesis continued even at the highest cell density levels which could be reached. The intervals of the cell cycle were determined on one glioma line. Cells inhibited in crowded cultures were arrested in G1. The results imply that at least a proportion of neoplastic human glia lines retain a degree of topoinhibition, i.e. are still sensitive to growth restraint induced by increased cell density. However, topoinhibition was never as complete as among normal cells, since possibly cell density‐independent (“autonomous”) multiplication was maintained at a fairly high rate even at the abnormally high cell densities which all neoplastic lines attained.
A quantitative system for assay of malignant transformation by chemical carcinogens using a clone derived from BALB/3T3
Authors: Kakunaga Takeo
Published: February 2007

A31–714, a subclone isolated from clone A31 of the BALB/3T3 line showed a high degree of contact inhibition and an extremely low incidence of spontaneous transformation. Treatment of this subclone with 4‐nitroquinoline‐1‐oxide, 3‐methylcholanthrene, benzo(a)pyrene or N‐methyl‐N'‐nitro‐N‐nitrosoguanidine produced foci of multilayered growth on the background of contact‐inhibited monolayer within 2 to 4 weeks. In this system the transformation frequency can be determined quantitatively on either an inoculated cell basis or a surviving cell basis. The transformation frequency increased with the concentration of carcinogens within a certain range, and was affected by the duration of treatment and the cell density at the time of treatment. Treatment with DMSO alone or with the non‐carcinogenic substances, 4‐nitroquinoline, 4‐aminoquinoline‐1‐oxide, phenanthrene and pyrene, did not cause any transformation. The cytotoxic effects of carcinogens were not directly correlated with the transformation frequencies. All transformed cell lines derived from each focus showed characteristics known as the indices of malignant transformation, such as a criss‐cross pattern or piling up of cells, a high saturation density and the ability to grow progressively in soft agar. When the transformed cells were injected into the skin of the back of newborn or adult mice at a dose of 106 cells, fibrosarcomas were produced at the site of injection after 3–6 weeks. Neither untreated A31–714 cells nor morphologically untransformed cells in cultures with foci produced tumors on injection at a dose of 107 cells. In general, transformed cells had a reduced cloning efficiency, and almost the same susceptibility to the cytotoxic effects of carcinogens as untransformed cells, though these properties varied in different lines.
Immunogenicity and immunosensitivity of SV40‐transformed cells with different oncogenic potentials
Authors: Stillström J.
Published: February 2007

ME1 C9, a cloned line of mouse embryo cells, transformed by SV40 in vitro, and its more malignant progeny, ME1 C9‐V15, derived from a tumor of the 15th consecutive passage of ME1 C9 in vivo, were compared as regards immunogenicity and immunosensitivity in syngeneic CBA mice. A threshold zone of immunization with ME1 C9 and ME1 C9‐V15 cells in the range of 103‐105 irradiated cells was indicated, after which the immunized animals were 1,000 times more resistant. There was no significant difference in immunizing potential between ME1 C9 and ME1 C9‐V15 cells at any dose level. A heterologous line of SV40‐transformed rat cells was significantly less immunogenic than the syngeneic cells. The growth of ME1 C9‐V15 cells could be enhanced after immunization with spontaneously transformed ME3 cells or with a small dose of ME1 C9 cells. The immunosensitivity of the ME1 C9 and ME1 C9‐V15 cells was measured as a sensitivity index in uniformly immunized animals. Both lines appeared immunosensitive if the animals were sufficiently immunized. The less malignant cells, ME1 C9, appeared more immunosensitive than the more malignant ME1 C9‐V15 cells in seven out of nine experiments, but only once was the difference between the lines significant. The interpretation of differences of sensitivity indices is discussed, and a possible role of blocking factors is considered.
Expression of fetal antigens and tumor‐specific antigens in SV40‐transformed cells. I. Serological analysis of the antigenic specificities
Authors: Ting Chou‐Chik , Ortaldo John R. , Herberman Ronald B.
Published: February 2007

The fetal antigens expressed in a variety of tumors have previously been shown to be different from tumor‐specific antigens. The present study on the expression of fetal antigens in various SV40‐transformed cells showed that more than one fetal antigen may be found in these cell lines, and that the expression of fetal antigens was not directly related to the function of the SV40 genome. These fetal antigens were not found in syngeneic spleen cells but were found in the normal spleens of some other strains of mice.
Intracerebral transplantation of human rhabdomyosarcoma cells into fetal and newborn kittens
Authors: Gardner Murray B. , Johnson Eden Y. , Rasheed Suraiya , McAllister Robert M.
Published: February 2007

A human rhabdomyosarcoma cell line (RD) was transplanted intracerebrally in fetal kittens in an attempt to repeat the recovery of an RD‐114‐like virus. No virus was recovered from six such transplant tumors. Similar transplant tumors formed by RD cells productively infected prior to transplantation with feline leukemia virus or murine sarcoma virus released viruses that were not detectably altered from the parent viruses.
The stimulatory effects of bearing primary methylcholanthrene‐induced tumors upon the murine lymphoreticular system
Authors: Smith Richard T. , Konda Susumu
Published: February 2007

These studies explore mechanisms involved in the apparent immunodeficiency associated with the development of primary tumors. Methylcholanthrene fibrosarcomas were induced in five inbred strains of mice, and the cellular parameters of spleen‐cell immunologic function were measured either after the tumors reached a constant size or following a specific period of growth. T‐cell numbers, as indicated by the subpopulation susceptible to anti‐θ and complement cytotoxicity, and T‐cell functions including PHA mitogenicity, primary alloantigen recognition, and T cooperation were decreased proportionately, although they remained unchanged or were increased absolutely. Susceptibility to LPS mitogenicity, an apparent B‐cell function, was increased relatively and absolutely. The B‐cell function of anti‐SRBC production was also increased. Colonyforming units increased in number, but they were insufficient to account for significant proportions of the spleen cell population. It was concluded that the animal bearing a primary MCA tumor is deficient in neither T nor B cells and that the effect of the tumor upon immune function is stimulatory.
Plasma‐cell and tumor‐associated membrane antigens of mouse plasmacytoma MOPC‐315 and MOPC‐460
Authors: Comoglio P. M. , Forni G.
Published: February 2007

Rabbit and syngeneic mouse antisera produced against solubilized membrane antigens from plasma‐cell tumors MOPC‐315 and MOPC‐460 recognize neoplastic plasma‐cell antigens that are not detectable in normal tissues. The rabbit antisera showed precipitating antibodies against two tumor‐associated antigens expressed in both MOPC‐315 and MOPC‐460 cells and unrelated to plasma‐cell‐specific antigens or myeloma proteins. These were called embryo (EM) antigen and A‐particle‐associated (Aa) antigen. The EM‐antigen seemed to be related to mitotic activity and was also expressed by a mouse adenocarcinoma and by mouse embryo cells. The Aa‐antigen was detected by immuno‐precipitation in all of nine different mouse tumors. Its purification by reverse immunoadsorption demonstrated that it consisted of two related components. Syngeneic mouse antisera showed precipitating antibodies against only part of the Aa‐antigen determinants recognized by rabbit antisera. Lastly, one mouse antiserum precipitated with an antigen of unique specificity detectable on MOPC‐315 only.
Sensitivity to guinea‐pig serum of hamster cells transformed in vitro by two strains of the rous sarcoma virus
Authors: Bataillon G.
Published: February 2007

Whereas cloning efficiency in soft agarose of untransformed hamster BHK 21/13 cells is strongly reduced when the cells are pre‐incubated with guinea‐pig (GP) serum, BHK 21/13 cells transformed by the Bryan strain of Rous sarcoma virus are unaffected by the same treatment; sensitivity of BHK 21/13 cells transformed by the Schmidt‐Ruppin strain of Rous sarcoma virus is intermediate. It is suggested that GP serum contains heterospecific cytotoxic substances directed against a xenogeneic surface antigen present on BHK 21/13 cells, and to a lesser extent, on BHK 21/13 cells transformed by SR‐RSV; this antigen is not detectable on the surface of BHK 21/13 cells transformed by the B‐RSV but can be “unmasked” after treatment with neuraminidase.
Potentiation of RSV rescue from rsv‐transformed “poorly” virogenic cell lines by 5‐bromodeoxyuridine treatment before fusion with chick embryo fibroblasts
Authors: Donner L. , Sainerová H. , Svoboda J. , Scherneck S.
Published: February 2007

The rescue of RSV from the “poorly” virogenic RSV‐transformed rat lines LW13‐RsK1 and LW13‐RsK4 was achieved only after treatment with 5‐bromodeoxyuridine (BUdR) before fusion with chicken embryo fibroblasts. Treatment of these lines with mitomycin C (MC) before fusion did not result in RSV rescue. Treatment of RSV‐transformed non‐virogenic mouse lines, RVA4 and RVP3, with BUdR or MC before fusion with chick embryo fibroblasts did not lead to the production of RSV.
Antigenic relatedness of simian C‐type viruses
Authors: Rangan S. R. S.
Published: February 2007

The two simian C‐type viruses, gibbon lymphoma (GLV) and simian sarcoma (SSV‐1), are compared for their antigenic relatedness by serum‐neutralization techniques appropriate for the respective virus. While GLV was neutralized completely by its homologous antiserum, its replication was merely delayed by anti‐SSV‐1 serum. Both anti‐SSV‐1 and anti‐GLV antisera neutralized SSV‐1 and its associated virus (SSAV‐1). It is concluded that the simian viruses are antigenically related but distinct from each other and unrelated to feline leukemia virus. The results also suggest that SSV‐1 and SSAV‐1 possess identical envelope antigens.
Active specific immunotherapy of minimal residual tumor: Excision plus neuraminidase‐treated tumor cells
Authors: Rios Angelyn , Simmons Richard L.
Published: February 2007

Tumor growth can be severely inhibited and total regression occasionally induced when mice bearing firmly established transplantable syngeneic tumors are challenged with living tumor cells which have been treated in vitro with Vibrio cholerae neuraminidase (VCN) plus mitomycin C. Tumors greater than 1 cm in diameter will not regress. The present experiments were designed to determine if immunotherapy could be effective if the tumor mass were surgically reduced. Three tumors previously shown to be susceptible to active specific immunotherapy with VCN‐treated tumor cells were utilized. Two time periods were selected, that in which VCN‐treated tumor cells will normally inhibit growth (12–15 days post inoculation) and that time period after which VCN‐treated tumor cells alone are insufficient to inhibit growth (25 days post inoculation). Three types of tumor excision were investigated; minimal reduction in tumor mass by wedge excision, subtotal reduction of tumor mass by tumor enucleation, and attempts at total excision with narrow margins. The combination of subtotal or total excision plus challenge with VCN‐treated tumor cells was significantly more effective than either excision or immunotherapy alone. The best results were obtained with the MC‐43 methylcholanthrene‐induced fibrosarcoma and a transplantable mammary adenocarcinoma (M‐2). No synergistic or additive effect of specific active immunotherapy and surgical therapy was noted in the B16 melanoma, which tends to metastasize early after implantation and grows as an indistinct infiltrative local tumor mass rather than a well‐pronounced local growth. Results strongly suggest that the reduction in tumor mass by surgical means might allow active specific immunotherapy to become an effective anti‐tumor adjunct.
Immunogenetic aspects of nasopharyngeal carcinoma: I. Differences in HL‐A antigen profiles between patients and control groups
Authors: Simons M. J. , Wee G. B. , Day N. E. , Morris P. J. , Shanmugaratnam K. , De‐Thé G. B.
Published: February 2007

This paper reports the results of two studies which compared the HL‐A profile of predominantly Chinese patients with nasopharyngeal carcinoma to that of suitably chosen controls. The first study demonstrated a significant increase in the proportion of NPC patients in whom less than two second locus antigens were detectable. The second confirmatory study also demonstrated the same phenomenon at a high level of statistical significance, and furthermore showed a significant elevation among the NPC patients of the frequency of HL‐A2. Both the elevation of the HL‐A2 frequency and the deficit of detectable second locus antigens remained significant after application of the most conservative correction factor for the number of antigens investigated. Various sources of bias have been considered and appear not to have appreciably influenced the results. The results are discussed in terms of the postulated genetic basis of the elevated risk for NPC among the Chinese.
Interactions between the peripheries of ehrlich ascites tumor cells as indicated by the binding of colloidal iron hydroxide particles
Authors: Weiss L. , Subjeck J. R.
Published: February 2007

An attempt was made to correlate contact between Ehrlich ascites cells growing in stationary culture, with the distribution of colloidal iron hydroxide particles adsorbed to their surfaces after fixation. It was observed that significantly fewer particles were adsorbed to regions of surfaces at which microvilli from other cells were “aimed”, than in adjacent regions. Although the precise relationship of this alignment to cell contact is problematical, the fact that alignment occurs at all is indicative of interactions taking place between regions of cell surfaces, and the modification of these surfaces as a result of the interactions.
Properties of flat variants of murine sarcoma virus transformed non‐producer cells isolated after high‐temperature passage
Authors: Gazdar Adi F. , Stull Harold B. , Chopra Harish C. , Ikawa Yoji
Published: February 2007

High‐temperature passage (40.5°C) increased the incidence of flat variants obtained from Kirsten sarcoma virus transformed BALB/3T3 non‐producer cells from less than 0.1% to 4%. The flat variants had growth properties similar to those of the BALB/3T3 line. The variant lines did not release detectable type C virus, but some contained intracisternal type‐A particles. Super‐infection of the variants with murine leukemia virus (MuLV) resulted in retransformation and release of sarcoma virus. Some of the variant lines may be suitable indicator cells for the assay of MuLV. Modal chromosome numbers of the variant lines were considerably higher than those of their progenitor cell line.