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Results for “Continuous transformation”

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At least 19 recordsLinked to original sources
PubMed1976

Induction of tumors in Syrian hamsters by a human renal papovavirus, RF strain.

Injection of RF virus (RFV), a papovavirus isolated from human urine, into newborn Syrian hamsters induced subcutaneous sarcomas in 50% of the recipients with 18- to 48-week latent periods. Transplantation of 2 X 10(6) primary RFV-induced tumor cells into weaning hamsters caused tumors in 100% of the recipients within 1-2 weeks. Continuous tissue culture cell lines were established from two primary tumors; one of these was transplantable. An in vitro-transformed continuous cell line (RF-194) obtained by infection of primary hamster embryo fibroblasts with RFV was transplantable in weaning hamsters. Neither infectious RFV nor virion antigens were detected in transformed cells. No RFV was recovered when transformed cells were fused with permissive, human embryo kidney cells by means of inactivated Sendai virus. Immunoperoxidase staining was used to show that all three RFV-transformed cell lines contained an intranuclear T-antigen closely similar to that of simian virus 40(SV40)-infected cells. Most hamsters (84%) with primary or transplanted RFV tumors responded with antibodies that reacted with RFV T-antigen and the T-antigen of SV40-infected cells. Likewise, hamster antisera against SV40 T-antigen cross-reacted with RFV T-antigen. Adsorption of RFV T-antisera with an excess of lyophilized SV40-transformed cells removed all detectable activity against SV40 T-antigen but left significant activity against RFV T-antigen. The reciprocal adsorption produced an antiserum spedicic for SV40 T-antigen. Thus human and simian papovavirus T-antigens were related but immunologically separable.

Animals↗
PubMed1978

A diploid rat liver cell culture. IV. Malignant transformation by aflatoxin B1.

Chronic exposure of a cloned rat hepatocyte culture (RL-PR-C) to a subtoxic, sublethal dose of aflatoxin B1 resulted in malignant transformation. Continuous exposure to aflatoxin B1 caused increasing tumorigenic potential as tested by back injection into isogenic animals. Control cultures exhibited spontaneous transformation, although approximately 20 passages beyond the chemically induced event. Neither aflatoxin-treated nor control cultures exhibited cytopathological morphology, formation of cell foci, growth in soft agar, or irregular fibroblast-like growth patterns that could be specifically related to the onset of tumorigenic potential. In general, those parameters commonly used to monitor fibroblast cultures for transformation in vitro were not applicable for assessing the tumorigenic potential of these epithelial cells. Karyotypic analyses revealed no specific chromosomal aberrations associated with aflatoxin treatment; however, chromosomal instability was a property of the tumorigenic cell populations. Injection of both aflatoxin-treated and control cultures at passage 56 resulted in tumors indicative of both carcinoma and sarcoma indicating to us the multipotency of these epithelial cells transformed in vitro.

Aflatoxins↗
PubMed1978

Infection of human cell cultures with bovine visna virus.

Fibroblastoid cell cultures derived from leukaemic bone marrow were successfully infected with BVV. After 2 months of subcultivation the cultures showed the appearance of foci of altered cells, suggestive of malignant transformation. Such foci were absent in non-inoculated cultures. Both control and inoculated cultures had a limited life span, i.e. neither of them could be developed into continuous transformed cell lines. The presence of at least some BVV genome functions in the inoculated cells was demonstrated (i) by immunofluorescence using a reference BVV serum, (ii) by detection in the supernatant culture fluid of sedimentable particles bearing RNA-dependent DNA polymerase activity with preference for Mg2+ ions, and (iii) by electron microscopic detection of scarce cell-associated virus particles in one of the infected cultures. Infectious BVV could not be rescued. In contrast to leukaemic bone marrow cultures, diploid human embryonic fibroblasts of various origin could not be infected with BVV.

Animals↗
PubMedDate not supplied

[Microbiological transformation of carbohydrates. Glucose isomerization into fructose by washed cells of Streptomyces sp. strain 29].

Glucose-fructose transformation by washed and packed cells of Streptomyces sp. 29 was studied. The cells grown on the nutrient medium containing xylose and Co and Mg salts were capable to perform glucose-fructose isomerization. The cellular activity depended in a great degree on the temperature, pH and initial glucose concentration; to a lesser extent on Co and Mg ions present in the incubation mixture, and did not depend on the age of the culture (within 8-69 hours). The activity reached its maximum at 70-80 degrees C, pH 7.0 and a low concentration of glucose (10(-3) M). Under these conditions the yield of fructose was 50% from the initial glucose concentration (or 100% from the theoretical value). Washed cells of Streptomyces sp. 29 packed into a thermally controlled column continuously transformed glucose to fructose during 24 days with a yield of 30-44%.

Biotransformation↗
PubMed1977

The ultrastructure of the interfollicular epidermis of the hairless (hr/hr) mouse. V. The cytoplasm of the horny cells.

The ultrastructure of horny cells in the interfollicular epidermis of the hairless mouse and in the mouse with hair has been studied with particular emphasis on changes in the cytoplasm through the horny layer. Horny cells from the two strains have a similar appearance, and the horny layer can be divided into three sublayers, each with a different ultrastructure. It is suggested that in vivo the same arrangement of densely packed filaments and fibrils which represents the keratin pattern in the basal sublayer is preserved throughout the horny layer. However, the filaments and interfilamentous substance seem to undergo a continuous transformation, which possibly results in a disintegration of the filaments when desquamation of the uppermost cell takes place.

Animals↗
PubMed2025

Prenatal organophosphate ester exposure and epigenetic changes at birth: a characterization of the methylome in the ECHO cohort.

BACKGROUND: Prenatal exposure to organophosphate esters (OPEs) affects multiple child health domains. Alterations to the DNA methylome are a plausible mechanism through which these changes occur. This study characterized DNA methylation signatures at birth associated with prenatal OPE biomarkers. METHODS: We included 736 mother-infant pairs from 7 sites in the Environmental influences on Child Health Outcomes (ECHO) Cohort. Five OPE biomarkers were quantified in maternal urine samples collected during the second and third trimesters and modeled as log2-transformed continuous variables. Using covariate-adjusted linear regression, we tested associations between OPE biomarkers and locus-specific, regional, and global cord blood DNA methylation changes measured by Illumina 450&#xa0;K and EPIC arrays, and gestational epigenetic age measured by the Knight gestational age epigenetic clock generated with measures from the 27&#xa0;K, 450&#xa0;K, and EPIC arrays. When feasible, we examined relationships by sex. FINDINGS: Global hypomethylation at multiple regions was associated with BDCPP concentrations (p&#xa0;=&#xa0;0.003 to 0.02, coef&#xa0;=&#xa0;-0.002). Differentially methylated regions annotated to PCDHGB1 and SLC43A2 were associated with BDCPP and DPHP concentrations, respectively (FDR q&#xa0;<&#xa0;0.05). In sex-specific analyses, global hypomethylation was associated with prenatal BDCPP (p&#xa0;=&#xa0;0.006 to 0.03, coef&#xa0;=&#xa0;-0.0003 to -0.0002) and DBUP_DIBP (p&#xa0;=&#xa0;0.01, coef&#xa0;=&#xa0;-0.0007 to -0.0006) concentrations in females; and global hypermethylation was associated with DBUP_DIBP concentrations in males (p&#xa0;<&#xa0;0.05, coef&#xa0;=&#xa0;0.0004). BCETP concentrations were significantly associated with decelerated epigenetic aging at birth in females (p&#xa0;<&#xa0;0.05, coef&#xa0;=&#xa0;-0.05). INTERPRETATION: Prenatal exposure to OPEs impacts child methylation at birth, suggesting a potential mechanism for the association between prenatal OPE exposure and child health outcomes.

Humans↗
PubMed1977

A continuous line of Rous sarcoma virus-transformed chick embryo cells.

A continuous line of Rous sarcoma virus (RSV)-transformed chick embryo cells was established. The cells, designated RTAZ-1, which constitute the only known line of continuously growing RSV-transformed cells of chick embryo origin, grow rapidly, display uniform morphology, and perpetually release large amounts of RSV (Rous-associated virus, type 1). RTAZ-1 cells display a heteroploid chromosome complement with 92-94 chromosomes characteristic of chicken cells. Molecular hybridization studies demonstrated that DNA from these cells hybridized with normal chick DNA but not with human (KB) cell DNA, thus providing additional evidence of the chicken origin of RTAZ-1.

Animals↗
PubMed1979

Continuous lines of RSV-transformed embryo cells and peritoneal macrophages of Japanese quails.

Four continuous lines of RSV-transformed quail cells were established; QERC-31F and QERC-31N cells derived from quail embryo cells and PERP and PERY cells from adult quail peritoneal macrophages. Marked morphological difference was noted between QERC-31F and QERC-31N; the former showed fusiform shape and the latter nodular shape. Both PERP and PERY showed macrophage-like morphology with phagocytic capacity. All four cell lines contained gs antigen and gp 85. Production of transforming virus was found in QERC-31N, PERP and PERY. In spite of failure in production of transforming virus, EQRC-31F was demonstrated to produce C-type particles by electron microscopy and to contain tumor-specific surface antigen by in vivo immunization and in vitro microcytotoxicity tests.

Animals↗
PubMed1977

Continued presence of similar transformation-associated antigens related to murine oncornavirus proteins in -ransformed cells, morphological revertants, and cells restricted in the expression of transformation.

The possible alteration of transformation-related antigens in cells that revert to a normal phenotype but that continue to retain the viral genome, has been investigated in [3H]glucosamine-labeled extracts of rat cells exhibiting a reversible temperature-dependent restriction in the expression of transformation and in a comparison of a morphologically altered mouse cell transformed by the Kirsten sarcoma virus with a flat revertant mouse cell derived from the morphologically transformed cells. With the use of normal goat serum in the presence of dibutyryl cyclic 3':5'-adenosine monophosphate, some differences became obvious in the rat cells restricted in the expression of transformation. However, use of specific antiserum to murine leukemia virus revealed in every case the presence of major components that exhibited an electrophoretic mobility corresponding to about 100,000 daltons both in the parent and revertant mouse cells and in the rat cells exhibiting either untransformed or transformed growth properties. The glycoprotein components detected only by the immune serum may represent a cellular macromolecule antigenically related to an interspecies C-type viral species whose concentration is increased in transformed cells.

Antigens, Neoplasm↗
PubMed1975

Transformation of horse skin cells by type-C sarcoma viruses.

A horse skin cell line (E. Derm, NBL-6, CCL-57) was susceptible to focus formation by the Kirsten mouse sarcoma virus, feline sarcoma virus (ST stain) and the MSV pseudotypes with woolly monkey, gibbon monkey, RD-114, AT-124, baboon placenta and murine xenotropic (BALB/c 3T3 and C57L/JD) type-C viruses. Foci were detected within 5 days after infection and the transformed cells continued to produce infectious virus and group-specific antigen of their respective type-C leukemia viruses. The transformation efficiency of various type-C sarcoma viruses in horse cells was also very high.

Animals↗
PubMed2026

Systematic evaluation of one-dimensional-to-two-dimensional near-infrared spectroscopy transformations with deep learning for quantifying coconut sap adulteration.

Near-infrared (NIR) spectroscopy have limitations when combined with deep learning (DL) algorithms because they rely on low-dimensional datasets. Therefore, we investigated the potential of transforming one-dimensional (1D) NIR spectra into two-dimensional (2D) spectrograms using synchronous and asynchronous techniques and the continuous wavelet transform (CWT) and their effectiveness by integrating with DL for detecting adulteration in coconut sap. NIR spectra (12,500-4000&#xa0;cm-1) were collected from binary mixtures (0%-100%;w/w). The performance of all DL (convolutional neural networks-CNN, AlexNet and ResNet) models was compared with that of partial least squares (PLS). The models were ranked in the mentioned order based on their performances: 2D-CWT&#xa0;>&#xa0;2D-asynchronous > 2D-synchronous > 1D/2D-PLS. The important features of the best model can be explained and visualized using gradient-weighted-class-activation-mapping. The findings highlight that the 1D-to-2D NIR data transformation combined with DL is a highly robust approach because it addresses the feature representation gap in NIR data and effectively captures the spatial-spectral correlations.

Spectroscopy, Near-Infrared↗
PubMed1977

Calcium content and distribution as a function of growth and transformation in the mouse 3T3 cell.

Total Ca content and that fraction of Ca sensitive to removal by the chelator ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA) have been investigated in the mouse 3T3 cell as a function of growth stage, transformation with SV40 virus, and serum levels of the media. Cells were allowed to grow through several doublings in media containing (45)Ca. The cellular content of (45)Ca was used to access total cell Ca. That fraction of (45)Ca removed by EGTA was presumed to represent primarily surface-localized Ca. The data are expressed on a per cell volume basis to compensate for size differences as a function of growth stage and transformation. During exponential growth phase, the 3T3 cell contains 525pmol Ca/mul cell volume. Of this, approx. 457 pmol/mul is not removable by EGTA and, presumably, is cytoplasmically located. This value is in close agreement with previous studies on the HeLa cell (470 pmol Ca/mul cell water after the removal of the surface Ca). The low level of EGTA- removable Ca present in the 3T3 cell during early exponential growth (68 pmol Ca/mul cell volume) increases progressively with increasing cell density, and upon quiescence it is sevenfold greater. In contrast, SV40- transformed 3T3 cells growing exponentially possess total levels of Ca which are approximately two-thirds the levels of the normal 3T3 cell. However, their EGTA-sensitive Ca is not significantly different from that of exponentially growing, normal 3T3 cells. As the transformed cells continue to grow at high density, their total ca and their sensitivity to EGTA do not change, in contrast to the normal 3T3 cell. Thus, an increase in Ca associated with the cell surface appears to be correlated with growth inhibition. This has been investigated further by regulating growth of the normal and transformed cell with alterations in the serum level of the media. In 4 percent calf serum the normal cell is stopped from continued proliferation. Growth stoppage under these conditions is characterized by a nearly fourfold increase in EGTA-removable Ca, similar to the increase observed upon quiescence in depleted 10 percent serum. Similar treatment of the transformed cell does not reduce its growth rate, nor does it significantly alter Ca distribution. However, at 0.5 percent medium serum levels, the SV40 3T3 growth rate is substantially reduced and, under these conditions, EGTA-removable Ca increases twofold.

Blood↗
PubMed1978

Glioblastoma multiforme: morphology and biology.

Glioblastoma multiforme, representing about 50% of all gliomas, encompasses a group of intrinsic tumours of the brain in later years (age peak around 50 years), the morphological hallmarks of which are an ensemble of variations in tumour cell and tissue structure featuring its biological malignancy. Glioblastoma, while sometimes appearing as a distinct "primary" tumour type, is usually accepted as an extreme manifestation of anaplasia and dedifferentiation of glia, mostly astrocytic. The astrocytic nature of most glioblastomas has been confirmed by ultrastructural studies and progressive differentiation of tumours maintained in organotypic tissue culture. Reproducible experimental models are particularly induced by oncogenic RNA (oncorna) viruses. The cell kinetic parameters are similar to those of other solid malignant tumours except for a comparatively low growth fraction of glioblastoma. The frequent occurrence of giant cells as well as of regressive changes with necrosis and vascular responses are indirect (secondary) indicators of malignancy which coincide with histochemical (enzymatic anisochronia) and biochemical data (lower level of glia specific S100 protein than in differentiated gliomas). Vascular proliferation, a characteristic feature of glioblastoma, may occasionally progress to sarcomatous transformation with development of gliosarcomas (mixed glial-mesenchymal tumours). While dissemination of glioblastoma through the cerebrospinal pathways is not uncommon, extraneural distant metastatic spread is rare, and usually observed after craniotomy. The results of modern neuro-oncology support the pathogenetic view that glioblastoma results from neoplastic transformation of glial elements with continuing dedifferentiation. This transformation can be experimentally induced by various factors including oncogenic DNA (oncorna) viruses by using a reverse transcriptase, while there is indirect evidence for an oncorna-virus information in human glioblastoma. The significance of immunological factors in the pathogenesis of brain tumours and in the course of neoplastic transformation of glia is not yet understood, but both morphological and immunological data are in favour of a cell mediated immunological reaction against tumour-specific antibodies. Since immunological factors and changes in cytokinetics are apparently active after the transformed tumour cells proliferate, all available therapeutic methods, including radiation, chemotherapy, and immunotherapy of glioblastoma only influence the final stages of neoplastic development with clinical manifestation of the tumour. In spite of modern combination and multimodality therapy schemes the prognosis of glioblastoma is still poor.

Adult↗
PubMedDate not supplied

[Comparative study of the morphofunctional organization of tissues of different regions of the rat brain in culture].

The morphological organization and spontaneous electrical activity of neurones of the hippocampus, visual cortex and cerebellum of one- two-day old rats were studied during prolonged cultivation (up to 35 days) of explants under indentical conditions in vitro. Differentiation of cells, myelinization of axons and formation of synapses between the neurones were observed. A continuous and periodic types of unit activity were recorded which, for the hippocampus did not depend on the time of cultivation and units' location in the explant. The cerebral cortex cultures displayed a transition of continuous unit activity to a periodic one after a two-week development of the explants in vitro. The process coincides with the increase in the number of synapses in the culture and their structural maturation. The periodic discharges observed in mature cultures of the cerebral cortex and in the central part of the cerebellum explants, are transformed into continuous ones under the action ofmagnesium ions.

Animals↗
PubMed1978

Lymphocytes transformed by Epstein-Barr virus. Induction of nuclear antigen reactive with antibody in rheumatoid arthritis.

Sera from approximately two-thirds of patients with rheumatoid arthritis contain an antibody which is reactive with a nuclear antigen present in human B-lymphocyte tissue culture cells. The immunological reaction can be demonstrated by precipitation and immunofluorescence. Evidence is present that the reactive nuclear antigen is associated with Epstein-Barr (EB) virus-transformed lymphocytes. Normal human peripheral blood lymphocytes did not contain the nuclear antigen reactive with rheumatoid arthritis sera, but after infection with EB virus, they showed increasing amounts of reactive nuclear antigen as the cells were transformed into continuous lines. Several established human and simian lymphocyte cell lines known to carry EB viral genomes were shown to contain rheumatoid arthritis-associated nuclear antigen. Evidence is presented which suggests that the rheumatoid arthritis-associated nuclear antigen is different from the previously described EB nuclear antigen.

Antibodies↗
PubMed2026

A study on the directed engineering and multiple transformations of cannabidiolic acid synthase to enhance the expression level of the recombinant enzyme.

To increase the activity of cannabidiolic acid synthase (CBDAS) and its expression levels in yeast, this study focused on the CBDASG183V-N482W mutant. Using computer-aided techniques and literature reviews, four mutation sites were further identified, resulting in the mutant CBDASH114E-S116A-C176Y-G183V-N328Q-N482W. The CBDAS gene was integrated into the Pichia pastoris genome via multiple transformation rounds, and relative enzyme activity was analyzed using high-performance liquid chromatography. The results of the molecular docking analysis revealed factors such as increased intermolecular forces, shorter bond lengths, and an increased number of amino acid-substrate interaction sites, which may have contributed to the enhanced catalytic activity of the mutant. The concentrations of CBDA and CBD produced by the CBDASH114E-S116A-C176Y-G183V-N328Q-N482W mutant were 71.543 ng/mL and 75.163 ng/mL, respectively, which were 11.87% and 11.53% greater than those produced by the CBDASG183V-N482W mutant. The recombinant CBDAS strain obtained after two consecutive transformations of the CBDASH114E-S116A-C176Y-G183V-N328Q-N482W vector presented the highest CBDAS expression levels and CBD and CBDA yields; compared with those obtained after a single transformation, the CBDA and CBD yields increased by 9.77% and 12.65%, respectively. In addition, the tolerance of the recombinant strain to induction culture conditions was analyzed, revealing that the strain could be induced to express the protein at temperatures ranging from 20 to 45&#xa0;&#xb0;C and at pH values ranging from 3 to 9, with optimal expression observed at 30&#xa0;&#xb0;C and pH 6. These findings provide theoretical and technical support for the production of enzyme preparations for the in vitro-directed biosynthesis of cannabidiol.

Molecular Docking Simulation↗
PubMed2024

Accessing and exploring the unusual chemistry by radical SAM-RiPP enzymes.

Radical SAM enzymes involved in the biosynthesis of ribosomally synthesized and post-translationally modified peptides catalyze unusual transformations that lead to unique peptide scaffolds and building blocks. Several natural products from these pathways show encouraging antimicrobial activities and represent next-generation therapeutics for infectious diseases. These systems are uniquely configured to benefit from genome-mining approaches because minimal substrate and cognate modifying enzyme expression can reveal unique, chemically complex transformations that outperform late-stage chemical reactions. This report highlights the main strategies used to reveal these enzymatic transformations, which have relied mainly on genome mining using enzyme-first approaches. We describe the general biosynthetic components for rSAM enzymes and highlight emerging approaches that may broaden the discovery and study of rSAM-RiPP enzymes. The large number of uncharacterized rSAM proteins, coupled with their unpredictable transformations, will continue to be an essential and exciting resource for enzyme discovery.

S-Adenosylmethionine↗