SEARCH · PubMed Health

Results for “Serial Passage”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1978

In vitro analysis of proliferating epithelial cell populations from the mouse mammary gland: fibroblast-free growth and serial passage.

Normal and neoplastic mouse mammary epithelial cells were cultured in nutrient medium containing D-valine substituted for L-valine. Fibroblast overgrowth was prevented and epithelial cell functions and morphology were retained in cultures maintained in D-valine medium up to 2 months. A nonenzymatic technique was devised to dissociate epithelial cell monolayers. The combined use of this dissociation buffer and D-valine nutrient medium made it possible to passage serially normal and neoplastic mammary epithelial cells. Normal cells were derived from mammary glands of animals stimulated with exogenous hormones for various periods. The period of in vivo hormonal stimulation influenced the ability of normal mammary epithelial cells to attach and proliferate in primary and serially passaged cultures. A greater proportion of cells derived from glands following 2 to 4 weeks of hormonal stimulation were recovered after replating and showed higher labeling indices during serial passage than cells from unstimulated or 5- to 7-week stimulated groups.

Adenocarcinoma↗

PubMed1978

Maintenance of biological and biochemical characteristics of human colorectal tumours during serial passage in immune-deprived mice.

The effect of serial passage in immune-deprived mice on certain biological and biochemical parameters has been studied in a series of 6 human colorectal tumour xenografts. Histological integrity is maintained for up to 10 serial passages, together with production of epithelial mucins and carcinoembryonic antigen. Passaged tumours retain human lactate dehydrogenase and glucose-6-phosphate dehydrogenase isoenzyme patterns and a human chromosome constitution. The induction of a murine tumour has been identified in this system, and the importance of routine checks for the presence of human tissue during serial passage is stressed.

Animals↗

PubMed1979

Structure and origin of defective genomes contained in serially passaged herpes simplex virus type 1 (Justin).

Restriction enzyme and hybridization analyses have revealed that high-density DNA prepared from passage 15 of serially passaged herpes simplex virus type 1 (Justin) contains three major classes of modified viral DNA molecules, each composed of distinct but closely related types of repeate units. The DNA sequences within the three types of repeat units are colinear with the DNA sequences located at the right end (between coordinates 0.94 and 1.0) of the parental herpes simplex virus type 1 genome. Thus, the three types of repeat units each contain the entire repeat sequence (ac) (which brackets the unique sequences of the small [S] component of herpes simplex virus type 1 DNA) and differ only with respect to the amount of unique S sequences which they contain. The three classes of high-density DNA molecules were found to be stably propagated between passages 6 and 15 of this series.

Base Sequence↗

PubMed1976

Loss or persistence of the differentiated state of simian virus 40-induced hamster tumor cells before and after serial passage in culture.

The transformed cells that arise from among the hamster epithelial and mesenchymal cells exposed to SV40 in vitro are, as a rule, fibroblastoid and pleomorphic rather than epithelioid. Moreover, the neoplasms that these transformed cells induce in the allogeneic host are spindle cell sarcomas and pleomorphic sarcomas rather than carcinomas. Since this phenomenon may result from cellular dedifferentiation in culture, to the extent that the anaplastic morphology and lack of specialized function can no longer suggest the cell or origin, we investigated the fate of the differentiated state of cells of three types of SV40-induced hamster tumors before and after serial passage in vitro. The tumors evaluated were three reticulum cell sarcomas, three osteogenic sarcomas, and two lymphosarcomas of B-cell origin. Our data demonstrate that reticulum cell sarcoma cells lose their morphological differentiation soon after the original tumors are dissociated into cell suspensions but preserve their phagocytic activity throughout their in vitro passage. Osteogenic sarcoma cells lose their differentiated phenotype and their capacity to form osteoid during but not before their serial passage in culture. Lymphosarcoma cells preserve their lymphoid morphology and their ability to produce immunoglobulin even after many in vitro passages. These results indicate that, in many types of SV40-induced tumors, neoplastic cell dedifferentiation, following serial passage in culture, is responsible to a great extent for the emergence of new cell phenotypes lacking in morphological and functional features characteristic of the cells originally transformed by SV40.

Animals↗

PubMed1992

Identification of murine thymocyte populations capable of extensive proliferation in serially passaged thymic organ cultures.

Using the approach of titrating precursor cells into mouse thymus organ cultures and serial passage, we have sought to compare the proliferative capacities of cells derived from adult and embryonic thymus and related haemopoietic tissues. We find that cells derived from the liver and thymus of day 14 embryos are capable of extensive proliferation in such cultures (surviving for at least 12 weeks) whereas cells derived from adult sources (blood and thymus) display a much more restricted lifespan and potential for division. Analysis of sequentially passaged thymic lobes shows that cells lacking CD4 and CD8 (CD4- and CD8-) and a subset of single CD8 positives are selectively expanded in these cultures. A preliminary study of the CD4-CD8- populations in these lobes suggest that these include cells expressing surface CD3 (in association with either TCR alpha beta or TCR gamma delta) and a subset of CD4-CD8-CD3-. These findings suggest that sequential passage of thymocytes in organ culture may be a useful alternative strategy for characterising cells with high proliferative potential, resident in the thymus and also for probing their lineage relationships.

Animals↗

PubMed1978

The DNA of serially passaged herpes simplex virus: organization, origin, and homology to viral RNA.

High-density DNA prepared from serially passaged herpes simplex virus contains three major classes of modified viral DNA molecules. The altered DNA molecules are composed of multiple repetitions of sequences derived from the right-hand side of the S region of the parental plaque-purified viral DNA. The repeat units contained in the three types of high-density DNA share most of their DNA sequences but differ with respect to a small region derived from the unique sequences of the S component of HSV-1 DNA. Hybridization of the defective DNA to HSV-infected cell RNA shows that the high-density DNA contains sequences complementary to both early and late viral transcripts.

Base Sequence↗

PubMed1978

Growth characteristics of human colorectal tumours during serial passage in immune-deprived mice.

The growth characteristics of 6 human colorectal tumours have been examined during serial passage in both male and female immune-deprived mice. Exponential growth is a characteristic feature, especially on very early passages. Growth rates in 5 out of the 6 tumour lines increase during the first few transplant generations. This is accompanied by a shorter exponential growth phase and an increased slope of the growth curves. Lag phases and growth rates for individual tumours are variable within a passage. Growth rates for tumours maintained within the same host are similar, and are at least partially influenced by the host. In one tumour line examined in detail, the increased growth rate is attributable to a decreased cell-loss factor, and the difference in growth rate between human colorectal tumours and their corresponding xenografts may therefore largely be due to a difference in the contribution of this factor.

Animals↗

PubMed1992

Modification of foot-and-mouth disease virus O1 Caseros after serial passages in the presence of antiviral polyclonal sera.

Foot-and-mouth disease virus (FMDV) shows a remarkable antigenic variability and, like other RNA viruses, presents a high rate of mutation. It has been proposed that selection exerted by antibodies of the host could play a major role in the rapid evolution of FMDV. The present work reports the selection of FMDV antibody-resistant (Nr) populations after serial passages of a cloned FMDV O1 Caseros strain on secondary monolayers of bovine kidney cells in the presence of subneutralizing antiviral polyclonal sera (APS). After a limited number of passages, i.e., 29, under selective pressure, the virus population showed the following characteristics: (i) increased resistance to neutralization by APS (Nr), (ii) altered electrophoretic mobility of its structural viral proteins (VP1), and (iii) alterations at the RNA nucleotide sequence that codes for the major antigenic site of VP1. These acquired characteristics were detected at passage 15 and remained unmodified throughout successive passages. These results document a rapid selection and fixation of specific mutations in response to immunological pressure. In addition, the findings that (i) mutations not related to APS selection were not detected and (ii) after 29 passages at a high multiplicity of infection without immunological pressure, the RNA sequence that codes for VP1 remained unmodified clearly demonstrated that FMDV O1 Caseros presents in vitro a remarkable unexpected genetic stability.

Amino Acid Sequence↗

PubMed1976

Strain selection during serial passage of Trichoplusia in nuclear polyhedrosis virus.

Two strains of a nuclear polyhedrosis virus (NPV) of Trichoplusia ni were isolated on the basis of plaque morphology. They are designated as MP (having greater than 30 polyhedra per nucleus) and FP (having fewer than 10 polyhedra per nucleus). Serial, undiluted passage of plaque, purified MP nonoccluded. Virus (NOV) in tissue culture led to the production of the FP phenotype detectable at passage 9. With continued serial, undiluted passage, FP became the predominant strain. Comparative growth curves showed that FP NOV are released faster than MP NOV. MP morphology was not observed after 14 serial, undiluted passages of plaque-purified FP. By the plaque neutralization assay, NOV from both strains of virus was neutralized by the homologus and heterologous antisera. The FP phenotype was observed when FP virus was grown in culture at 17, 22, and 27 C. Hence, the FP phenotype was not considered to be the result of temperature-inhibited crystallization of polyhedrin under standard tissue culture conditions. The NOV of both strains killed insects when injected directly into the hemocoele of T. ni larvae. Only MP inclusion bodies were virulent per os. The FP inclusion bodies fed to cabbage looper larvae did not kill, and no infectious agent could be detected in the hemolymph. Electron micrographs of MP polyhedra showed bundles of nucleocapsids of normal length within the polyhedra, whereas FP polyhedra contained heterogeneous, electron-dense material, which could account for their lack of pathogenicity.

Animals↗

PubMed1977

Role of endogenous murine leukemia virus in immunologically triggered lymphoreticular tumors. I. Development and use of oncogenic cellfree preparations serially passaged in vivo.

Cellfree extracts (CFEs) prepared from (BALB/cJ X A/J)F1 (CAF1) and (BALB/cJ X C57BL/6J)F1 (CB6F1) mice in which a graft-versus-host reaction (GVHR) has been induced are known to be oncogenic, but only after a protracted latent period (mean, 16 mo). Serial passage of such CFEs in successive generations of syngeneic mice inoculated at birth led to the development of two separate oncogenic preparations, the CA serioes in CAF, mice and the CB series in CB6F, mice, in which the mean latent period was reduced to 6 and 12 months, respectively. Both oncogenic preparations contained infectious B-tropic murine leukemia virus (MuLV) and particles with the ultrastructural characteristics of MuLV. No other kind of virus particle was seen. When these preparations were injected into infant syngeneic mice, B-tropic MuLV could be detected in the reticular tissues as early as 2 weeks thereafter. The virus persisted in the reticular tissues and was present in the lymphoreticular tumors that subsequently developed. However, if the same preparation was injected into young adult recipients, there may have been transient MuLV replication, but the virus subsequently disappeared from the reticular tissues and no lymphoreticular tumors developed. Previous experiments showed that MuLV was present in CFEs prepared from CAF, animals with the GVHR but absent in those of normal control mice. Since the lymphoreticular tumors arising in mice with the GVHR were the same as those induced by the CA and CB MuLV preparations, it was concluded that tumorigenesis in mice with the GVHR was caused by endogenous B-tropic MuLV activated by the immunologic disturbance.

Animals↗

PubMed1979

Tumor-associated antigens of chemically-induced murine tumors; the emergence of MuLV and fetal antigens after serial passage in culture.

Using radioiodinated Staphylococcus aureus protein A [125I]SPA to measure syngeneic, allogeneic and heterogeneic IgG bound to murine tumor cells, we performed a serological analysis of surface antigens of 8 solid tumors and 2 leukemias of BALB/c mice (3 chemically-induced colon carcinomas, 3 chemically-induced sarcomas, 1 murine leukemia virus (MuLV) induced leukemia, 1 irradiation induced leukemia, 1 spontaneous melanoma and 1 spontaneous sarcoma). We were able to detect and distinguish between at least five separate antigenic specificities on these tumors. Unique tumor-associated antigens were found on 3 of the tumors, MuLV related antigens on 8 tumors, fetal antigens on 7 tumors and two distinct common antigens on 7 tumors (common antigen 1 (CA-1) on 5 tumors and common antigen 2 (CA-2) on 2 tumors). Neither of the common antigens was found to be sarcoma, carcinoma or tissue-tupe specific. A number of tumors which did not originally express either MuLV or fetal antigens in primary cultures expressed these antigens after several serial passages in vitro.

Animals↗

PubMed1977

Establishment of an Epstein-Barr virus-negative B-cell lymphoma line from a Japanese Burkitt's lymphoma and its serial passage in hamsters.

An Epstein-Barr virus (EBV)-negative lymphoma line (JBL) was established in vitro from pleural effusion of an EBV-seropositive 29-year-old Japanese female with Burkitt's lymphoma. JBL cells as well as her original lymphoma cells bore monoclonal surface IgM with lambda light chains. The JBL line grew in single cell suspension with a doubling time of 30 hours. Attempts were made to serially transplant JBL cells in antilymphocyte serum-treated newborn hamsters; intraperitoneal implantation of 1-3 X 10(7) cells gave rise to invasive tumors in all recipients with death after 10 to 14 days. The hamster-passage line, now in the 9th passage, has been converted to an ascitic form with progression to leukemia in some animals. A "starry sky" pattern closely resembling the human tumor material was preserved in every tumor through serial animal passage.

Animals↗

PubMed1978

Serial passages of larval Echinococcus granulosus from equine origin in mice. I. Infection with protoscolices.

Starting with protoscolices from Echinococcus granulosus cysts of equine origin it was possible to isolate and maintain several "strains" of the parasite in mice through successive transfers of protoscolices. The most advanced strain is now in its 7th generation. Several criteria to evaluate the results are presented and discussed. It is concluded that serial echinococcosis of E. granulosus through passages with protoscolices is a practical method to maintain different strains for fundamental and applied comparative studies.

Animals↗

PubMed1979

Duck virus hepatitis: serial passage of attenuated virus in ducklings.

The safety of three attenuated virus vaccines of proven efficacy against duck virus hepatitis was assessed by controlled laboratory studies which involved the serial transmission of the virus through groups of two-day-old ducklings known to be susceptible to the disease. Each vaccine was initially derived from a different source. Enhancement of virulence which resulted in deaths from the disease in test groups of ducklings occurred in each instance.

Animals↗

PubMed1978

Loss on serial passage of rhesus monkey kidney cells of proteolytic activity required for Sendai virus activation.

Primary and secondary cultures of rhesus monkey kidney cells supported multiple-cycle replication of Sendai virus, but later passages lost this ability, and this was reflected in decreased plaque formation. Multiple-cycle replication also did not occur in LLC-MK2 cells, a continuous line of RMK cells. Failure of replication in serially passed cells was correlated with a decrease in proteolytic cleavage of a viral surface glycoprotein (Fo), and the ability of cells to support multiple-cycle replication and plaque formation could be restored by the addition of trypsin (0.3 microgram/ml) to the overlay medium. The use of wild-type virus, which requires trypsin, and protease activation mutants that require chymotrypsin or elastase for activation has provided evidence that the activating protease supplied by primary or secondary cells has trypsin-like activity. Inactive virus, with uncleaved Fo glycoprotein, absorbed to primary or secondary cells but did not infect them, even though such cells possess the enzyme that is capable of cleaving the Fo glycoprotein of virus synthesized in these cells. The inability of these cells to activate adsorbed virus indicates that the activating protease that they possess is inacessible to adsorbed virus, although it can act on the Fo glycoprotein during virus maturation in these cells. These data provide a biochemical explanation for the failure of later passages of a cell strain or a continuous cell line to support the replication of a paramyxovirus.

Animals↗

PubMed1979

Neuroendocrine cells in serially passaged rat stomach cancers induced by MNNG.

Five gastric carcinomas, induced in inbred Wistar rats by oral administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) dissolved in drinking water, were successfully transplanted to isologous rats. The transplants grew to a size of 10 to 35 mm in diameter within 8 to 25 weeks of implantation. In one case, serial transplantation were maintained up to the 11th generation, with occurrence of distant metastasis in the 3rd generation. Histological histochemical, and electron microscopical comparison of the original and transplanted tumors revealed that (1) the original tumors were quite well differentiated, forming either papillary or tubular structures, whereas the transplants were more anaplastic and pleomorphic showing often solid nests; and (2) tumor cells with gastrointestinal differentiation and cells with neuroendocrine differentiation were present and evenly distributed in both the original and the serially transplanted tumors. As it is unlikely that the normal and neoplastic neuroendocrine cells are growing side-by-side with and independently of the epithelial neoplastic components in the present series of transplants, the findings strongly suggest (1) the multidirectional potency of the inbred rat stomach carcinoma cells and (2) the common neoplastic origin of the epithelial and neuroendocrine components.

Animals↗

PubMed1978

Serial passages of larval Echinococcus granulosus from equine origin in mice. II. Infections with sterile cysts.

Sterile secondary E. granulosus cysts less than or equal to 1 mm in diameter, collected from mice 6-13 months after experimental infection were transferred to helminth-free mice. They developed into larger cysts showing fertility and daughter cyst formation at autopsy 9--14 months p.i. Average growth of the largest cyst per mouse, expressed in log volume (microliter), amounted to 0.30 +/- 0.03 per month; average growth of all cysts per mouse, expressed in log weight (mg) amounted to 0.27 +/- 0.02 per month. An inversed ratio was found between total parasite weight and number of cysts injected. The practical importance of these observations is discussed.

Animals↗

PubMed1978

Serial passages of larval Echinococcus granulosus from equine origin in mice. III. Infections with sterile daughter cysts.

Daughter cysts 0.2-3.0 mm in diameter from secondary Echinococcus granulosus cysts, collected from mice one year after experimental infection, were transferred to fresh mice. The metacestodes developed into larger cysts showing fertility and daughter cyst formation at autopsy 9-14 months post infection. The average total growth of all cysts per mouse expressed in log weight (mg) amounted to 0.25 +/- 0.03 per month. Thus, for the maintenance of the parasite in mice, daughter cysts can be used as successfully as protoscolices and small 'latent' cysts.

Animals↗