Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chimerism”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 721 records · Page 40Linked to original sources
PubMed2005

Chimeric synthetic peptides as antigens for detection of antibodies to Trypanosoma cruzi.

Six chimeric synthetic peptides (QCha-1, QCha-2, QCha-3, QCha-4, QCha-5, and QCha-6) incorporating antigenic sequences of two immunodominant repeat B-cell epitopes of Trypanosoma cruzi were synthesized by conventional solid-phase peptide synthesis. The antigenic activity of these peptides was evaluated by UltramicroEnzyme-linked immunosorbent assay (UMELISA) by using panels of positive Chagasic sera (n=82), while specificity was evaluated with samples from healthy blood donors (n=44) and patients with other infectious diseases (n=86). The antigenicity of the chimeric peptides in solid-phase immunoassays was compared with that of the monomeric peptides. Data demonstrated that the chimeric peptide QCha-5 was the most reactive because it detected antibodies to parasite efficiently. The results indicate that chimeric peptide as coating antigen is very useful for the immunodiagnosis of Chagas' disease.

Animals↗
PubMed2003

Stability of murine, chimeric and humanized antibodies against pre-S2 surface antigen of hepatitis B virus.

We have constructed a humanized antibody with specificity for the pre-S2 surface antigen of hepatitis B virus (HBV) by grafting the complementarity determining regions (CDRs) of parental murine monoclonal antibody (mAb) into human anti-Sm antibody framework regions. The humanized antibody has a substitution at position 94 in a framework region of the heavy chain variable region, and exhibits the same antigen binding affinity as the parental murine monoclonal and chimeric antibodies. In order to assess the stability of these antibodies, thermal inactivation of the parental, chimeric and humanized antibodies was analyzed. Fifty percent inactivation of the chimeric and humanized antibodies was observed at 63.7 degrees C and 68.7 degrees C, respectively, compared to 55.0 degrees C for murine antibody. The humanized antibody also exhibited increased stability against denaturant. Guanidine-induced unfolding monitored by the changes in fluorescence intensity at 360 nm showed that midpoints of the transition of the chimeric and humanized antibodies were 2.47 M and 2.56 M, respectively, whereas that of the murine antibody was 1.36 M.

Animals↗
PubMed2004

Expression vectors for chicken-human chimeric antibodies.

The chicken is a useful animal for preparation of antibodies that are reactive with highly conserved mammalian molecules. For further clinical application of chicken antibodies, we constructed the novel expression vectors for chicken-human chimeric antibodies, pcSLCgamma1, pcSLCgamma4 and pcSLCkappa. These vectors had the following characteristics: (1) any chicken variable regions from hybridomas or a phage display library can be easily introduced; (2) the variable regions are able to be expressed in different immunoglobulin isotypes; and (3) the chimeric antibodies can be highly expressed in either transiently or stably transfected eukaryotic cells (COS-7 and CHO-K1 cells). Western blot analysis of the chimeric antibodies revealed that the expressed products were of the predicted size, structure and specificity. These results indicate that these vectors are useful tools for the chimerization of chicken antibodies.

Animals↗
PubMed2005

Synthesis, conformational and pharmacological studies of glycosylated chimeric peptides of Met-enkephalin and FMRFa.

Our previous study showed that a chimeric peptide of Met-enkephalin and FMRFamide, YFa (YGGFMKKKFMRFa) not only caused antinociception and potentiated morphine analgesia but also blocked the development of tolerance and physical dependence. In the continuation of that study three chimeric analogues of YFa, [Ser5]YFa, [O-Glu-Ser5]YFa and [O-Gal-Ser5]YFa, were synthesized. To increase the bioavailability and penetration of blood brain barrier (BBB), glycosylated analogues, [O-Glu-Ser5]YFa and [O-Gal-Ser5]YFa, have been synthesized by solid phase peptide synthesis by building block method using anomeric acetate activation method. Circular dichroism studies showed that all the three chimeric peptides are stable and have a propensity for adopting helical conformation in the presence of membrane mimicking solvent. In comparison of parent chimeric peptide YFa, helicity of [Ser5]YFa, [O-Glu-Ser5]YFa and [O-Gal-Ser5]YFa has decreased. Pharmacological studies using tail-flick latency in mice showed that [O-Glu-Ser5]YFa have increased analgesia and bioavailability in comparison of [O-Gal-Ser5]YFa and non-glycosylated analogue [Ser5]YFa. Exhibition of enhanced analgesia by [O-Glu-Ser5]YFa as compared to [O-Gal-Ser5]YFa seems to be due to preference of GLUT-1 transporter system for glucose.

Animals↗
PubMed2005

Stable multilineage chimerism across full MHC barriers without graft-versus-host disease following in utero bone marrow transplantation in pigs.

Stable engraftment of hematopoietic progenitors and multilineage chimerism following in utero bone marrow transplantation could be a promising modality for treatment of prenatally diagnosed blood dyscrasias. For treatment of these diseases, stable chimerism in the myeloid and erythroid lineages is important because it is anticipated that donor-derived cells will compensate for defects in these host lineages. In the present study, a preparation of bone marrow that includes fresh, unmanipulated marrow mixed with T-cell-depleted marrow to achieve 1.5% T-cell content, was injected into the intrahepatic portion of the umbilical vein of porcine fetuses at mid-gestation. Donor hematopoietic progenitor cell engraftment was assessed in fetal liver and recipient bone marrow postnatally by donor-specific polymerase chain reaction of colony-forming units. Chimerism was assessed in lymphoid tissues and peripheral blood by flow cytometry. Graft-versus-host disease (GVHD) was assessed by histological analysis of biopsies of skin, bone marrow, liver, and intestine. In this report, we demonstrate that stable multilineage chimerism across a full major histocompatibility complex disparity can be achieved without GVHD through in utero bone marrow transplantation.

Animals↗
PubMed2006

Successful pregnancies after transplantation of frozen-thawed mouse ovaries into chimeric mice that received lethal-dose radiation.

OBJECTIVE: To study whether fecundity was recovered in mice into which umbilical cord blood cells (UCBCs) were transfused after lethal-dose radiation, followed by transplantation of frozen-thawed ovaries. DESIGN: Prospective basic research study. SETTING: Academic research laboratory. ANIMAL(S): Female C57BL/6 mice as recipients of UCBCs and ovaries, male B6C3F1 mice for mating, and green fluorescent protein (GFP)-transgenic mice: 18.5-day-old fetuses (-/+) for UCBCs and adult GFP mice (+/+) for ovarian tissues. INTERVENTION(S): The UCBCs were transfused into each irradiated mouse, with GFP+ ovaries transplanted 4 weeks later. The chimeric mice were mated 3 weeks after ovarian transplantation and were examined 14 to 16 weeks after the transfusion of UCBCs. MAIN OUTCOME MEASURE(S): Percentage of chimerism, number of GFP+ pups. RESULT(S): The percentage of chimerism in these mice tends to increase with the radiation dose. The recovery of fecundity was observed in the chimeric mice that were transplanted with fresh and previously vitrified ovaries after exposure to radiation. CONCLUSION(S): Even when the exposure dose of radiation administered as pretreatment is lethal, the fecundity of recipients can be maintained if their ovaries are cryopreserved before they are exposed to radiation.

Animals↗
PubMed2004

Tolerance in mixed chimerism - a role for regulatory cells?

The establishment of mixed hematopoietic chimerism induces life-long donor-specific organ graft tolerance while obviating the need for chronic immunosuppression. Recent advances have dramatically reduced the conditioning toxicity required to achieve mixed chimerism. We argue that the achievement of high levels of donor chimerism ensures life-long deletion of donor-reactive T cells, precluding and obviating the need for regulatory mechanisms in the maintenance of tolerance. However, in situations where high levels of donor chimerism cannot be established or sustained, control of immune responsiveness can be achieved through additional mechanisms, including regulatory T cells.

Graft Survival↗
PubMed2005

Targeted gene transfer to nigrostriatal neurons in the rat brain by helper virus-free HSV-1 vector particles that contain either a chimeric HSV-1 glycoprotein C-GDNF or a gC-BDNF protein.

Direct gene transfer into neurons has potential for both studying neuronal physiology and for developing gene therapy treatments for specific neurological conditions. Due to the heterogeneous cellular composition of the brain, cell-type-specific recombinant gene expression is required for many potential applications of neuronal gene transfer. The two prevalent approaches for achieving cell-type-specific expression are to use a cell-type-specific promoter to control recombinant gene expression or to modify a virus vector particle to target gene transfer to a specific cell type. Targeted gene transfer to multiple peripheral cell types has been described, but targeted gene transfer to a specific type of neuron in the brain has yet to be reported. Targeted gene transfer approaches with Herpes Simplex Virus (HSV-1) vectors have focused on modifying glycoprotein C (gC) to remove the heparin binding domain and add a binding activity for a specific protein on the cell surface. This study was designed to develop HSV-1 vectors that target gene transfer to cells that contain receptors for either glial-cell-line-derived neurotrophic factor (GDNF) or brain-derived neurotrophic factor (BDNF), such as nigrostriatal neurons. We isolated chimeric gC-GDNF or chimeric gC-BDNF constructs, and the resulting proteins were incorporated into HSV-1 virus particles. We performed helper virus-free HSV-1 vector packaging in the presence of each chimeric protein. The resulting vector stocks supported 2.2- to 5.0-fold targeted gene transfer to nigrostriatal neurons in the rat brain, compared to vector particles that contained wild-type (wt) gC. Gene transfer to nigrostriatal neurons by vector particles that contained chimeric gC-BDNF was reduced by preincubation with an anti-BDNF antibody. Targeted gene transfer to neurons that contain specific neurotrophic factor receptors may benefit specific physiological and gene therapy studies.

Animals↗
PubMed2006

Cloning, expression, and purification of a highly immunogenic recombinant gonadotropin-releasing hormone (GnRH) chimeric peptide.

To design an anti-gonadotropin-releasing hormone (GnRH) vaccine capable of eliciting strong immunogenicity, a gene fragment encoding a chimeric peptide was constructed using polymerase chain reaction and ligated into a novel expression vector for recombinant expression in a T7 RNA polymerase-based expression system. The chimeric peptide called GnRH3-hinge-MVP contained three linear repeats of GnRH (GnRH3), a fragment of the human IgG1 hinge region, and a T-cell epitope of measles virus protein (MVP). The expression plasmid contained the GnRH3-hinge-MVP construct ligated to its fusion partner (AnsB-C) via an unique acid labile Asp-Pro linker. The recombinant fusion protein was expressed in an inclusion body in Escherichia coli under IPTG or lactose induction and the target peptide was easily purified using washing of urea and ethanol precipitation. The target chimeric peptide was isolated from the fusion partner following acid hydrolysis and purified using DEAE-Sephacel chromatography. The purified GnRH3-hinge-MVP was determined to be highly homogeneous by IEF analysis and the N-terminal sequencing. Further, immunization of female mice with the recombinant chimeric peptide resulted in generation of high-titer antibodies specific for GnRH. The results showed that GnRH3-hinge-MVP could be considered as a candidate anti-GnRH vaccine.

Amino Acid Sequence↗
PubMed2005

Evaluation of mixed chimerism in bone marrow transplantation program in Croatia.

In this study we monitored mixed chimerism in 36 patients with various hematologic disorders. All of them underwent a classic conditioning regimen, 31 patients for related bone marrow transplantation (BMT) and 5 patients for unrelated BMT. DNA was isolated from peripheral blood, and samples were polymerase chain reaction (PCR) amplified for 5 short tandem repeat (STR) loci (TH01, VWA31, FES/FPS, F13A01, and SE33) and for one variable number of tandem repeats locus (D1S80). Samples were run on a 6% polyacrylamide gel in an automated ALFexpress sequencer. In all 36 donor-recipient pairs we found differences for at least two STR loci. In most cases the difference was observed for SE33 and D1S80 loci. Mixed chimerism (MC) was detected in 18 patients: 4 with unrelated BMT and 14 with related sibling donors. In 11 patients MC was detected in the early period after BMT, but was soon followed by full donor chimerism (FDC) in peripheral blood. In 5 cases patients MC appearing after FDC was established, and was predictive for the relapse. One patient showed alternating MC and FDC, but at the end showed only recipient cells and graft rejection. In conclusion, the PCR-STR analysis is a highly informative, fast, and simple screening method for monitoring chimerism in a BMT program.

Adolescent↗
PubMed2005

The virion-associated Gag-Pol is decreased in chimeric Moloney murine leukemia viruses in which the readthrough region is replaced by the frameshift region of the human immunodeficiency virus type 1.

The human immunodeficiency virus type 1 (HIV-1) requires a programmed -1 translational frameshift event to synthesize the precursor of its enzymes, Gag-Pol, when ribosomes from the infected cells translate the full-length viral messenger RNA. Translation of the same RNA according to conventional translational rules produces Gag, the precursor of the structural proteins of the virus. The efficiency of the frameshift controls the ratio of Gag-Pol to Gag, which is critical for viral infectivity. The Moloney murine leukemia virus (MoMuLV) uses a different strategy, the programmed readthrough of a stop codon, to synthesize Gag-Pol. In this study, we investigated whether different forms of the HIV-1 frameshift region can functionally replace the readthrough signal in MoMuLV. Chimeric proviral DNAs were obtained by inserting into the MoMuLV genome the HIV-1 frameshift region encompassing the slippery sequence where the frameshift occurs, followed by the frameshift stimulatory signal. The inserted signal was either a simple stem-loop, previously considered as the stimulatory signal, or a longer bulged helix, now shown to be the complete stimulatory signal, or a mutated version of the complete signal with a three-nucleotide deletion. Although the three chimeric viruses can propagate essentially as the wild-type virus in NIH 3T3 cells, single-round infectivity assays revealed that the infectivity of the chimeric virions is about three to fivefold lower than that of the wild-type virions, depending upon the nature of the frameshift signal. It was also observed that the Gag-Pol to Gag ratio was decreased about two to threefold in chimeric virions. Comparison of the readthrough efficiency of MoMuLV to the HIV-1 frameshift efficiency, by monitoring the expression of a luciferase reporter in cultured cells, revealed that the frameshift efficiencies were only 30-60% of the readthrough efficiency. Altogether, these observations indicate that replacement of the readthrough region of MoMuLV with the frameshift region of HIV-1 results in virions that are replication competent, although less infectious than wild-type MoMuLV. This type of chimera could provide an interesting tool for in vivo studies of novel drugs targeted against the HIV-1 frameshift event.

Animals↗
PubMed2006

Characterization of herpes simplex virus type 1 recombinants that express and incorporate high levels of HCV E2-gC chimeric proteins.

We report the construction of two HSV-1 recombinants encoding chimeric forms of the E2 glycoprotein of HCV-1a composed of the ectodomain of E2 (aa384-611 or 384-711) fused to different parts of the transmembrane and cytoplasmic domain of the HSV-1 gC glycoprotein (gC). The parental HSV-1, known as KgBpK(-)gC(-), is deleted for gC and the main heparan sulphate (HS) binding domain of gB, and it exhibits impaired binding (ca. 80%) to HS compared to the wild type virus KOS [Laquerre, S., Argnani, R., Anderson, D.B., Zucchini, S., Manservigi, R., Glorioso, J.C., 1998. Heparan sulphate proteoglycan binding by herpes simplex virus type 1 glycoproteins B and C, which differ in their contributions to virus attachment, penetration, and cell-to-cell spread. J. Virol. 72, 6119-6130]. We show that gC:E2 proteins are efficiently expressed and transported to the cell surface. We also demonstrate that HSV-1 can incorporate both gC:E2 chimeric proteins into particles and show that incorporation of both chimeric molecules in the viral envelope partially restored binding (ca. 20%) of the HSV-1 recombinants to heparan sulphate. Finally, we showed that the gC:E2ScaI chimeric glycoprotein was able to bind a recombinant form of hCD81 and virion-expressed gC:E2ScaI permitted the binding of the HSV-1 recombinant virus to the hCD81 molecule.

Animals↗
PubMed2004

At most three ES cells contribute to the somatic lineages of chimeric mice and of mice produced by ES-tetraploid complementation.

Chimeric or entirely embryonic stem (ES) cell-derived mice ("ES mice") can be produced by injecting ES cells into diploid (2n) or tetraploid (4n) host blastocysts, respectively. Usually, between 10 and 15 ES cells are injected into the host blastocyst, but it is not clear how many of the injected cells contribute to the somatic lineages, thus serve as "founder cells" of the embryo proper. We have used genetically labeled ES cells to retrospectively determine the number of founder ES cells that generate the somatic lineages of chimeric and of ES mice. ES cell clones individually labeled with provirus were mixed in equal numbers and injected into 2n or 4n blastocysts to generate chimeric or ES mice. Southern analysis of DNA from the resulting animals indicated that the somatic lineages were most often derived from one or two and sometimes from up to three founder ES cells. The number of founder cells was independent of the total number of cells injected into the host blastocysts. Our results are consistent with the notion that constraints of the host embryo restrict the number of ES cells that can contribute to a chimeric or an ES mouse.

Animals↗
PubMed2000

Mixed hematopoietic chimerism induces long-term tolerance to cardiac allografts in miniature swine.

BACKGROUND: Tolerance to cardiac allografts has not been achieved in large animals using methods that are readily applicable to human recipients. We investigated the effects of mixed hematopoietic chimerism on cardiac allograft survival and chronic rejection in miniature swine METHODS: Recipients were T-cell depleted using a porcine CD3 immunotoxin, and each received either of two nonmyeloablative preparative regimens previously demonstrated to permit the establishment of stable mixed hematopoietic chimerism across MHC-matched, minor antigen-mismatched histocompatibility barriers. Five to 12 months after the chimerism was induced, hearts from the original cell donors were heterotopically transplanted into the stable mixed chimeras. RESULTS: Cardiac allografts transplanted into untreated recipients across similar minor antigen barriers were rejected within 44 days (within 21, 28, 35, 39, 44 days among individual study subjects). In contrast, hearts transplanted into the mixed chimeras were all accepted long term ( > 153, > 225, > 286, > 362 days) without immunosuppressive drugs and developed minimal vasculopathy. CONCLUSIONS: Mixed hematopoietic chimerism, established in miniature swine using clinically relevant, non-myeloablative conditioning regimens, permits long-term cardiac allograft survival without chronic immunosuppressive therapy, significant vasculopathy, or graft-versus-host disease.

Animals↗
PubMed1999

N-terminal chimeric constructs improve the expression of sarcoplasmic reticulum Ca(2+)-ATPase in yeast.

Wild-type and chimeric constructs comprising rabbit sarcoplasmic reticulum (SR) Ca(2+)-ATPase and the N-terminal cytoplasmic portion of yeast plasma membrane H(+)-ATPase were expressed in yeast under control of a heat-shock regulated promoter. The wild-type ATPase was found predominantly in endoplasmic reticulum (ER) membranes. Addition of the first 88 residues of H(+)-ATPase to the Ca(2+)-ATPase N-terminal end promoted a marked shift in the localization of chimeric H(+)/Ca(2+)-ATPase which accumulated in a light membrane fraction associated with yeast smooth ER. Furthermore, there was a three-fold increase in the overall level of expression of chimeric H(+)/Ca(2+)-ATPase. Similar results were obtained for a chimeric Ca(2+)-ATPase containing a hexahistidine sequence added to its N-terminal end. Both H(+)/Ca(2+)-ATPase and 6xHis-Ca(2+)-ATPase were functional as demonstrated by their ability to form a phosphorylated intermediate and undergo fast turnover. Conversely, a replacement chimera in which the N-terminal end of SR Ca(2+)-ATPase was replaced by the corresponding segment of H(+)-ATPase was not stably expressed in yeast membranes. These results indicate that the N-terminal segment of Ca(2+)-ATPase plays an important role in enzyme assembly and contains structural determinants necessary for ER retention of the ATPase.

Animals↗
PubMed1992

Subjective mood state and perception of emotion in chimeric faces.

Levy, Heller, Banich, and Burton (1983) have shown that hemispheric activational, or arousal, style, as measured by direction and consistency of choice of the "happer face" on a free-viewing Chimeric Faces Test, is highly reliable and varies across individuals who otherwise presumably have similar cortical organization (e.g., right-handed college students). The current experiment asks whether such individual differences in hemispheric arousal style are moderated by long-term, in the sense of enduring, individual differences in mood, as measured by the Profile of Mood States (POMS) questionnaire. Like Levy et al.'s subjects, most of our subjects (126 right-handed college students) made most of their choices on the Chimeric Faces Test based on the emotional cue (the smile) positioned in the half of the face to the viewer's left, or left visual hemifield (LVH), whereas a small minority were equally consistent in making their choice based on the emotional cue positioned in the half of the face to the viewer's right, or right visual hemifield (RVH). Performance on the Chimeric Faces Test, however, proved to be unrelated to scores on the POMS questionnaire. This suggests that hemispheric arousal style, as indexed by the Chimeric Faces Test, is robust enough, for a population of normal right-handers, to transcend any differences in mood as measured by the POMS questionnaire.

Adolescent↗
PubMed2001

Functional expression of chimeric receptor genes in human T cells.

Tumor immunotherapy has been limited to date by the poor antigenicity of most tumors, the immunocompromised state of many cancer patients, and the slow tumor penetration and short half-life of exogenously-introduced anti-tumor antibodies. Our group has developed a model immunotherapy system using a chimeric construct containing an antibody V region fused to a T cell activation molecule (T body) introduced by transfection into cytotoxic T cell lines, or populations of activated primary T or natural killer (NK) cells. In this study we have optimized the conditions needed for efficient transduction of human peripheral lymphocytes (PBL) using retroviral vectors pseudotyped with the gibbon ape leukemia virus (GaLV) envelope. Selection of packaging cells producing high virus titers was performed following transfection with constructs containing the green fluorescent protein (GFP), and FACS sorting. As a model chimeric receptor gene we used a tripartite construct consisting of a single-chain anti-TNP antibody variable region linked to part of the extracellular domain and the membrane spanning regions of the CD28 coreceptor molecule and joined at its 5' end to a gene fragment encoding the intracellular moiety of the gamma activation molecule common to the Fcepsilon and Fcgamma receptors. Enriched preparations of retrovectors containing this chimeric receptor and the GFP gene could stably and efficiently transduce human PBL co-activated by anti-CD3 and anti-CD28 antibodies. In routine experiments, the transgene was expressed in 35-70% of the human T cells. Such lymphocytes express the chimeric receptors on their surface and upon stimulation with hapten immobilized on plastic they can produce IL-2. Transfectomas activated in this manner also undergo specific proliferation in the absence of exogenous IL-2. Moreover, the transduced lymphocytes could effectively lyse target cells expressing the TNP hapten on their surface. These studies establish the conditions for the optimal transfection of effector lymphocytes to redirect them against a variety of tumor targets.

CD28 Antigens↗
PubMed1998

Generation of chimeric monoclonal antibodies from mice that carry human immunoglobulin Cgamma1 heavy of Ckappa light chain gene segments.

Gene targeting in mouse embryonic stem (ES) cells was used to replace (i) the mouse immunoglobulin heavy chain (IgH) Cgamma2a gene segment (mCgamma2a) with the human Cgamma1 gene segment (hCgamma1), and (ii) the mouse immunoglobulin light chain (IgL) Ckappa gene segment (mC kappa) with its human counterpart (hC kappa). ES cells carrying these gene conversions were used to generate chimeric mice that transmitted the human alleles through the germ line. Mice homozygous for both gene alterations were generated by breeding. Serum from homozygous mutant mice contained comparable amounts of antibodies with chimeric kappa or mouse lambda light chains but only small fractions of basal serum IgG or antibodies elicited against immunizing agents contained chimeric heavy chains. A relative increase in immunogen-specific hCgamma1 antibodies was seen following immunization in combination with the saponin adjuvant QS-21. The effect of this was to shift the IgG1-dominated response to an IgG subclass profile that included significant amounts of IgG2a, IgG2b and IgG3 and chimeric IgG. The amounts of antibody secreted by hybridomas derived from mutant and wild-type mice were similar. Sequencing confirmed correct splicing of hCgamma1 and hCkappa gene segments to mouse J gene segments in hybridoma Ig gene transcripts. In conclusion, IgHhCgamma1/IgLhCkappa double mutant mice provide a useful animal model for deriving humanized antibodies with potential applications in immunotherapy and diagnostics in vivo as well as for investigating hCgamma1 associated functions.

Animals↗