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Biomedical subjects

T Wen

Publications and source records attributed to T Wen.

32 records · Page 2Linked to original sources
PubMed1995

Methylcholanthrene-induced mouse sarcomas express individually distinct major histocompatibility complex class I-associated peptides recognized by specific CD8+ T-cell lines.

Mouse sarcomas induced by methylcholanthrene (MC) are immunologically distinct even if they are induced in the same strain of mice. T-cell lines were derived from mice immunized against a series of syngeneic MC sarcomas on B6 background, known to carry unique tumor-specific transplantation antigens. Tumor necrosis factor-alpha (TNF-alpha) release assays concurred with the in vivo rejection tests. The strongest response in the TNF-alpha release was always obtained with the corresponding tumor, with very limited cross-reactivity against five other MC tumors or two virally induced B6 lymphomas. The specific TNF-alpha release from the anti-MC tumor CTL lines was mainly mediated by CD8+ cells. T-cell lines from intact and CD4-/- mice gave a similarly specific pattern. In contrast, T-cell lines derived from CD8-/- mice cross-reacted with several other MC-induced tumors. Peptides eluted from MC sarcomas under mild acid conditions were fractionated by reverse-phase high performance liquid chromatography and tested for their ability to sensitize the processing- and presentation-defective mutant RMA-S line. Only one high performance liquid chromatographic fraction from each of the three different tumor-derived peptide eluates capacitated RMA-S to induce TNF-alpha release and sensitized the cell to the cytotoxic effect of the corresponding tumor-specific T-cell line. A different Kb-restricted peptide fraction was active for each of the three MC sarcomas tested, indicating that they all expressed individually distinct peptide epitopes.

Animals↗
PubMed1995

Polyomavirus persists in CD4/8 double-knockout, but not in CD4 or CD8 single-knockout mice.

The effects of incomplete immunocompetence on possible persistence and reactivation of polyomavirus in adult mice were investigated by a polyomavirus-specific polymerase chain reaction (PCR). The presence of virus DNA was followed between 4 days and 2 months postinfection (p.i.) in polyomavirus-infected normal adult A/Sn mice and CD4-/- and CD8-/- single-knockout, as well as CD4-/-8-/- double-knockout BALB/c or C57BL/6 mice. The same study was performed in A/Sn mice immunosuppressed by thymectomy (THX), cytosine-beta-D-arabinofuranoside (Ara-C) treatment, and total body irradiation (TBI). Primary polyomavirus infection of CD4-/- or CD8-/- single-knockout mice was similar to that obtained in normal adult mice when followed by PCR. Viral DNA was detected in a limited number of organs during 4 weeks p.i., but was no longer observed after 1-2 months. In contrast, the virus could be detected in most organs of CD4-/-8-/- double-negative mice and in THX-, Ara-C-, and TBI-treated adult mice and was still present 1-2 months p.i. In polyomavirus-infected normal adult mice a later immunosuppression did not lead to reactivation of the virus. Furthermore, if a second challenge of polyomavirus was administered 4 weeks after primary infection in both normal or recently immunosuppressed mice no viral DNA could be detected by PCR.

Animals↗
PubMed1995

Spontaneous resistance to acute T-cell leukaemias in TCRV gamma 1.1J gamma 4C gamma 4 transgenic mice.

The concept of tumour surveillance implies that specific and non-specific components of the immune system eliminate tumours in the early phase of malignancy. The immunological mechanisms that control growth of preneoplastic cells are, however, not known. T cells expressing gamma delta T-cell receptors (TCR) were first described as lymphocytes with reactivity against various tumour cells, which suggests that gamma delta T cells could mediate tumour surveillance. Here we show that TCRV gamma 1.1J gamma 4C gamma 4 transgenic mice are spontaneously resistant to acute T-cell leukaemias but cannot reject non-haematopoietic tumours. TCRV gamma 1.1J gamma 4C gamma 4+ hybridomas isolated from these mice react in vitro against almost all haematopoietic tumour cell lines tested. Recognition of tumour cells depends on the gamma delta TCR but is independent of major histocompatibility complex (MHC) class I, MHC class II, or TAP-2 peptide transporter expression. Ligand recognition is influenced by the murine Nromp gene, which confers resistance or susceptibility to tuberculosis, lepra and leishmaniasis. These data indicate that TCRV gamma 1.1+ T cells confer spontaneous immunity against haematopoietic tumours in vivo and link innate resistance to bacterial infections with tissue-specific tumour surveillance by gamma delta+ T cells.

3T3 Cells↗
PubMed1995

Allo-skin graft rejection, tumor rejection and natural killer activity in mice lacking p56lck.

Mice lacking the p56lck molecule (lck -/-) have a profound block in the maturation of thymocytes and a greatly reduced number of peripheral mature T cells. To analyze further the functions of the T cells developed in lck -/- mice in vivo, we evaluated the ability of lck -/- mice to reject allo-skin grafts and methylcholanthrene (MCA)-induced syngeneic fibrosarcoma, and also examined the biological activity of lck -/- natural killer (NK) cells. Mice lacking p56lck failed to reject skin grafts from either MHC-disparate or minor-histocompatibility-different donors, even after they had been primed with donor spleen cells. They also failed to reject the MCA-induced immunogenic syngeneic fibrosarcoma, MC57X. NK activity in mice lacking p56lck was normal, and there were no differences in the NK cell activation induced by poly(I).poly(C) stimulation or interleukin-2 stimulation (lymphokine-activated killer induction) between mice lacking p56lck and their immunocompetent heterozygous littermates. NK cells lacking p56lck mediated a normal antibody-dependent cell-mediated cytotoxicity (ADCC) response. The results of this study indicate that the loss of p56lck severely impairs the effectors of the immune system which mediate the rejection of allo-skin grafts and syngeneic tumors. The normal NK activity in lck -/- mice suggests that p56lck is not required for the development and activation of NK cells.

Animals↗
PubMed1992

[Hepatic segmentectomy using microwave tissue coagulator].

Hepatic segmentectomy using a microwave tissue coagulator guided by intraoperative ultrasonography is a new operative procedure, which our research unit was the first to start using from 1990. Up to now we have performed this kind of operation with success in 26 cases. Our results suggested that the new procedure simplified the original operation and greatly reduced the risk of hemorrhage and iatrogenic spread of the cancer cells during operation. Besides, this operation as a kind of definite anatomic hepatectomy can minimally resect the tumor bearing tissue in a radical fashion, while maximally preserve the tumor-free tissue of the liver.

Adult↗
PubMed1992

The Zavanelli maneuver: a different perspective.

Some obstetricians recommend the Zavanelli maneuver to resolve shoulder dystocia. Descriptions in the literature report an almost automatic ease in performance of the maneuver. We report a case of severe shoulder dystocia in which management with the Zavanelli maneuver and immediate cesarean was extremely difficult. The procedure involved exact reversal of all the cardinal movements of labor, and the delivery required terbutaline, general anesthesia, and added personnel to ensure successful extraction of the fetus. A delivery requiring the Zavanelli maneuver can be difficult to perform and may be worsened by insufficient personnel and inexact reversal of all the cardinal movements of labor.

Adolescent↗
PubMed1991

Clonality and methylation status of the Epstein-Barr virus (EBV) genomes in in vivo-infected EBV-carrying chronic lymphocytic leukemia (CLL) cell lines.

Directly growing Epstein-Barr virus (EBV)-carrying cell lines were established from a chronic lymphocytic leukemia (CLL) patient (PG) on repeated occasions. The lines carried the same ring chromosome 15 as the leukemia cells in vivo and were similarly trisomic for chromosome 12. They all showed the same JH rearrangement, indicating that they had arisen from the same B-cell progenitor. They also had the same single EBV-terminal repeat (TR), indicating that they had been generated by a single EBV infection event. It may be surmised that a single CLL cell had been infected by EBV in vivo and established itself subsequently as a subclone within the CLL population. This subpopulation persists in vivo but does not appear to expand with time. After explantation, it transforms into lymphoblastoid cells and proliferates selectively as immortalized lines. The leukemia-representative CLL lines were phenotypically indistinguishable from the B95-8 virus-transformed normal diploid cells of the patient, established in parallel by in vitro infection. They grew as typical LCL clusters and expressed the same B-cell activation markers. The methylation status of EBV-DNA was different in the CLL lines and the B95-8-virus-transformed LCLs. When Hpall- and Mspl- digested DNA was probed with BamHI C, E, H and W fragments, the CLL lines showed a mixture of methylated and unmethylated restriction fragments as in certain EBV-carrying Burkitt lymphoma (BL) lines. In contrast, the EBV-DNA of B95-8 virus-transformed normal diploid cells was completely unmethylated, as in other LCLs.

Antigens, CD↗
PubMed1991

Predominant rearrangements of the T cell receptor beta-chain gene in blood lymphocyte populations stimulated with autologous tumor cells suggest clonal T cell expansion in two of fourteen cases.

T cell responses against autologous tumors with samples from patients with a variety of tumors were examined. The abilities of T lymphocytes to lyse the autologous tumor cells were analyzed after short-term mixed lymphocyte/tumor cell cultures (MLTC). Southern blot analysis was used to evaluate whether particular rearrangements of the TCR beta-chain gene predominate in these cultures. Tumor specific lysis could be induced in a proportion of the mixed cultures. In two cases enrichment of T lymphocytes with similar TCR beta-chain gene rearrangements was detected after repeated stimulations with autologous tumor cells.

Blotting, Southern↗
PubMed1990

Presence of clonal T cell populations in chronic B lymphocytic leukemia and smoldering myeloma.

Clonality in the non-neoplastic T cell population was investigated in 21 patients with B cell chronic leukemic (B-CLL) or multiple myeloma (MM) by probing for TCR beta chain gene rearrangements using Southern blot analysis. In three patients with a benign form of B-CLL (stage 0), and in one patient with smoldering MM, evidence was found for predominant T cell clones. As cellular immunity against the malignant cells may be important in leukemia, the results are discussed in view of the potential role of T cell immunity in B-CLL and MM.

Aged↗
PubMed1988

A reevaluation of the amino acid sequence of human follitropin beta-subunit.

A collaborative study from two laboratories has been undertaken to re-evaluate the human follitropin beta-subunit sequence (hFSH beta), since areas of uncertainty remain in the wake of two earlier reports. The first report was by Shome and Parlow (1974). The second, by Saxena and Rathnam (1976), proposed revisions for sequence not definitively placed in the first study, as well as some differences in other placements. We have re-examined the sequence of the hFSH beta with more recent methodology. This has led to revision of certain areas of the sequence and resolution of differences between the two earlier proposals. Specifically, an -Ile-Ser- is established at 21-22, Asp at 41, Arg at 44, Lys at 46, and Glu at 111. These were areas of disagreement in the earlier proposals. A definitive placement of the residues around tryptophan-27 has now been obtained by three laboratories. C-terminal heterogeneity was observed with subunits ending at residue 107, 109, or 111. N-terminal heterogeneity has been observed in all preparations examined to date. A significant population of molecules with a proteolytic nick between residues 38-39 is noted. This is very likely an artifact of the collection and processing. The preparations examined in the present studies showed no evidence of residues 112-118 proposed by Saxena and Rathnam.

Amino Acid Sequence↗
PubMed1987

Sulfate and phosphate analysis in glycoproteins and other biologic compounds using ion chromatography. Application to glycoprotein hormones and sugar esters.

An ion chromatography procedure was devised for the simultaneous determination of phosphate and sulfate in the same sample. In order to eliminate interference from zwitterionic compounds (particularly amino acids and peptides) generated during hydrolysis of the phosphate- or sulfate-containing compounds a pretreatment step with a cation-exchange column was required. The detection of sulfate is approximately twice as sensitive as phosphate on a molar basis. The useful working range for sulfate was 200 pmole to 35 nmole with the ion chromatography employed; the range for phosphate was 400 pmole to 65 nmole. Linearity in this range was very satisfactory. Representative analyses are presented for hydrolyzates of several glycoprotein hormones and sugar sulfates and phosphate esters. Replicate analyses were +/- 3.0% or better. The glycoprotein hormone analyses for sulfate did not indicate whole integers per mole, suggesting mixtures of isohormones as has been found by others using chromatofocusing or isoelectric focussing and immunoassay.

Animals↗
PubMed1986

Characterization of cleavage products in selected human lutropin preparations. A protease-sensitive site in human lutropin beta subunit.

Low molecular weight fragments derived from the beta subunit of human lutropin have been frequently observed. These fragments are detected by polyacrylamide gel electrophoresis in sodium dodecyl sulfate following reduction of the disulfide bonds. A sample of human lutropin was identified that had a major portion of its beta subunit showing this proteolytic nick. Over 83% of the subunit was nicked based on reduction, carboxymethylation, and isolation of the low molecular weight fragments. This preparation had 53% of the activity of an intact human lutropin (radioligand assay). The proteolytic nick in the subunit was shown by N-terminal sequencing of the C-terminal fragments to be derived from three clips in a hexapeptide region (residues 44-49) characterized by hydrophobic alkyl side chains. Specific clips were on the amino side of Leu-45 (8%), Val-48 (45%) and Leu-49 (47%). Thus the proteolytic activity, presumably derived from the pituitary during processing, has a substrate specificity reminiscent of the bacterial protease, thermolysin.

Alkylation↗
PubMedDate not supplied

Adult X-linked immunodeficiency (XID) mice, IGM-/- single knockout and IGM-/- CD8-/- double knockout mice do not clear polyomavirus infection.

The importance of antibodies for elimination of polyomavirus infection and the prevention of virus induced oncogenesis was studied, X-linked immunodeficiency (XID) mice, IgM-/- single knockout and IgMI-/- CD8-/- double knockout mice, all defective in antibody production, and normal control mice were infected with polyomavirus as adults. The mice were followed for presence of polyoma DNA with a polyoma specific polymerase chain reaction (PCR) over 6 weeks post infection (p.i.), a time point at which polyomavirus DNA is no longer detected in normal adult infected mice. As expected, virus DNA was not detected in normal mice 6 weeks p.i. In both IgM-/- single knockout and IgM-/- CD8-/- double knockout mice a disseminated infection was still observed by 6 weeks p.i. and the latter group of mice succumbed around two months p.i. In XID mice, only one third of the mice were still positive for viral DNA 6 weeks p.i. No polyomavirus induced tumors were observed in any of the mice during the 2-4 month observation period.

Animals↗