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C Vaquero

Publications and source records attributed to C Vaquero.

At least 55 records · Page 3Linked to original sources
PubMed1995

HIV infection of choriocarcinoma cell lines derived from human placenta: the role of membrane CD4 and Fc-Rs into HIV entry.

We have shown previously that trophoblast cells from human placenta can be infected with HIV-1 and a productive infection established. Recently, (1991, J. Virol. 65, 2102-2107) Zachar et al. and D. M. Phillips and X. Tan (1992, AIDS Res. Hum. Retroviruses 8, 1697-1705) have described in vitro infection of choriocarcinoma cell lines. Using choriocarcinoma cell lines (JAR, BeWo, and FD25, a trophoblast-derived cell line) we have infected these cells with several laboratory strains of virus and have shown that this can be prevented either by sCD4 or by antibodies to CD4. This provides strong evidence that the infection may be through CD4. In addition, we have found that infection of JAR and FD25 cells by HIV-1/Lai was enhanced in the presence of human antisera to HIV-1. This supports an additional role for immunoglobulin receptors (Fc-R) in the entry of virus into the cell. We report here evidence that CD4 and Fc-R on the cell surface play crucial roles in the entry of HIV into such placenta-derived cell lines.

Antibodies, Monoclonal↗
PubMed1995

A natural antisense RNA derived from the HIV-1 env gene encodes a protein which is recognized by circulating antibodies of HIV+ individuals.

A naturally occurring antisense RNA, transcribed in the opposite direction and complementary to the envelope transcript, was identified in various cell lines chronically infected with HIV-1. In T cells, the antisense transcript is constitutively expressed and enhanced by activation with phorbol myristate acetate. The open reading frame corresponding to the antisense transcript, when expressed in vitro, encodes a protein with an apparent molecular mass of 19 kDa. Antibodies against this protein have been detected in several sera of HIV+ individuals and not in any of the noninfected control sera. These results indicate, for the first time, that expression of an antisense open reading frame most likely accompanies the HIV infection cycle in humans.

Base Sequence↗
PubMed1995

Defective cytokine expression but adult-type T-cell receptor, CD8, and p56lck modulation in CD3- or CD2-activated T cells from neonates.

Expression of IL-2, interferon-gamma, and IL-3 mRNA and proteins was investigated in peripheral blood mononuclear cells from cord blood after activation with phytohemagglutinin, CD2, or CD3 MAb. The results showed that interferon-gamma and IL-3 expression was decreased in cord peripheral blood mononuclear cells when compared with expression observed in adult peripheral blood mononuclear cells, irrespective of the stimulation used. In addition, in newborn cells a defect in IL-2 secretion and mRNA expression was observed in response to CD2 or CD3 MAb but not in response to phytohemagglutinin-mediated activation. We further analyzed the modulation of nonlymphokine genes under the same protocol of stimulations. The results indicate that in newborn cells, despite a reduced lymphokine expression observed after CD2 or CD3 MAb activation, the up-regulation of the T-cell receptor, CD8, and p56lck was similar to that found in adult cells, as was also found after phytohemagglutinin activation of both types of cells. These data are in favor of a deficient T-cell responsiveness to CD2 or CD3 MAb in newborn cells. This impairment of the T-cell response appears to selectively affect lymphokine gene expression because the modulation of other genes also implicated in T cell activation is not altered.

Adult↗
PubMed1995

Histologic effects of different suture materials in microsurgical anastomosis of the rat uterine horn.

OBJECTIVE: To evaluate the histologic effects and permeability rate of different suture materials in microsurgical anastomosis of the left uterine horn in Wistar rats. STUDY DESIGN: In this histologic study, 81 female Wistar rats were used. A transverse section and anastomosis were performed using three surgical techniques. The rats were divided into 15 experimental groups based on evaluation of three variations in microsurgical technique: (1) one-layer transmucosal anastomosis, (2) one-layer extramucosal anastomosis, and (3) two-layer transmucosal anastomosis. With each technique, five suture materials were used: 7/0 polyglycolic acid, 6/0 polyglactin, 7/0 polydioxanone, 7/0 silk and 7/0 polypropylene. RESULTS: The permeability rate was 86%. Polydioxanone persisted in 41% of cases at 90 days. Abnormal proliferation of mucosal epithelium was verified in 10% of cases. Polypropylene was responsible for the majority of foreign-body granulomas. Polydioxanone produced the smallest inflammatory reaction. CONCLUSION: The type of suture material did not influence the permeability rate. Use of nonabsorbable suture material altered the histologic structure the most and produced the greatest tissue reaction. The best results were obtained with polydioxanone. Monofilial sutures gave rise to fewer structural alterations than did multifilament sutures.

Absorption↗
PubMed1994

The 3a protein from cucumber mosaic virus increases the gating capacity of plasmodesmata in transgenic tobacco plants.

The 3a protein, encoded by RNA 3 of cucumber mosaic virus (CMV), is the putative movement protein of viral progeny in infected plants. An analysis of transgenic tobacco plants constitutively expressing the CMV 3a protein showed that the protein is accumulated in leaves at every stage of development. In fully expanded leaves the protein is immunodetectable mostly in a cell-wall-enriched fraction. Dye-coupling experiments using fluorescent-dextran probes were performed on fully expanded leaves to study the modifying effect of CMV 3a protein on the gating capacity of plasmodesmata. Movement of fluorescein-isothiocyanate-labelled dextran with a mean molecular mass of 10,000 Da, and an approximate Stokes' radius of 2.3 nm, was detected between cells of the 3a protein transgenic plants, but not in the control plants. These results are consistent with the idea that the CMV 3a protein is involved in the modification of plasmodesmata and, therefore, in the cell-to-cell spread of the virus.

Blotting, Western↗
PubMed1994

Translational frameshifting at the gag-pol junction of human immunodeficiency virus type 1 is not increased in infected T-lymphoid cells.

A frameshift event is necessary for expression of the products of the pol gene in a number of retroviruses, including human immunodeficiency virus type 1 (HIV-1). The basic signals necessary for frameshifting consist of a shifty sequence in which the ribosome slips and a downstream stimulatory structure which can be either a stem-loop or a pseudoknot. In HIV-1, much attention has been paid to the frameshift site itself, and only recently has the role of the downstream structure been examined. Here we used a luciferase-based experimental system to analyze in vivo the cis and trans factors potentially involved in controlling frameshifting efficiency at the gag-pol junction of HIV-1. We demonstrated that high-level frameshifting is dependent on the presence of a palindromic region located downstream of the site where the frameshift event takes place. Frameshifting efficiencies were found to be identical in mouse fibroblasts and the natural host cells of the virus, i.e., CD4+ human lymphoid cells. Furthermore, no increase in frameshifting was observed upon virus infection. Previous observations have shown that viral infection leads to specific alteration of tRNAs involved in translation of shifty sites (D. Hatfield, Y.-X. Feng, B.J. Lee, A. Rein, J.G. Levin, and S. Oroszlan, Virology 173:736-742, 1989). The results presented here strongly suggest that these modifications do not affect frameshifting efficiency.

Animals↗
PubMed1994

[The morphometric changes of chronic ischemia in the hepatocyte. An experimental study in the rat].

The effects of chronic ischemia on the rat hepatocyte are morphometrically analyzed in the present study. Rats Wistar-Lewis are used. Rats underwent a stenosis of the celiac artery by using a metallic guide. The interval between the experimentation until the sacrifice was 15, 30, 90, 180, and 360 days. We have performed a morphometric study using a semiautomated image analyzer system (VIDS III, Analytical Measuring Systems). Morphological disturbances in the chronic ischemia periods above mentioned can be measured: an increase in the hepatocyte area starting from 90 days of experimentation and also an increase in the hepatocyte perimeter starting from 30 days of ischemia. On the other hand, both the nuclear area and the nuclear perimeter are increased in every period studied. The number of hepatocytes per microscopic field doesn't show any change in relation to ischemia time. Cellular swelling suggests some degree of cellular hypoxia in contradiction with other observations.

Animals↗
PubMed1993

Sequences in the rev-responsive element responsible for premature translational arrest in the human-immunodeficiency-virus-type-1 envelope.

Cell-free translation in the presence of pancreatic microsomal membranes of the full-length envelope transcript of the human immunodeficiency virus type 1 (HIV-1) yielded the expected extensively glycosylated and immunologically reactive gp160 envelope-protein precursor. In addition to this gp160, a shorter glycoprotein, which we designated gp120*, was produced due to a premature translation arrest. Utilizing kinetic experiments, pulse-chase analyses and various gp160 envelope RNA mutants, we demonstrated that the in-vitro-produced gp120* was not formed by cleavage of the gp160 precursor or by internal initiation of translation. A gp120 produced before gp160 synthesis was completed, and, independent of the gp160 proteolytic processing, has been shown to be produced and sequestered in the endoplasmic reticulum of HIV-1-infected cells [Willey, R. L., Klimkait, T., Frucht, D. M., Bonifacino, J. S. & Martin, M. A. (1991) Virology 184, 319-329]. The specific translational arrest shown to occur in vitro was found to be dependent on the Rev-responsive element, since deletion of this highly structured sequence abolished the production of gp120*. We found that the combination of two contiguous putative stem loops of the Rev-responsive element, located at nucleotides 7494-7522 and 7525-7550 of the HIV-1 Rev-responsive-element sequence, was responsible for the production of this truncated protein. To our knowledge, these stem-loop structures, distinct from that known to bind the Rev protein, represent the first example responsible for the production of alternative products by premature translational arrest in higher eukaryotes.

Base Sequence↗
PubMed1993

The nucleotide sequence of the coat protein genes and 3' non-coding regions of two resistance-breaking tobamoviruses in pepper shows that they are different viruses.

The nucleotide sequence of the coat protein genes and 3' non-coding regions of two different resistance-breaking tobamoviruses in pepper have been determined. The deduced coat protein of an Italian isolate of pepper mild mottle virus (PMMV-I) consists of 156 amino acids and its 3' non-coding region is 198 nucleotides long. They have been found to be very similar in sequence and structure to those previously reported for a Spanish isolate (PMMV-S). In contrast, a Dutch isolate termed P 11 codes for a coat protein of 160 amino acids and its 3' non-coding region is 291 nucleotides long, which may have arisen by duplication. The nucleotide and the predicted coat protein amino acid sequence analysis show that this isolate should be considered as a new virus within the tobamovirus group. The term paprika mild mottle virus (PaMMV) is proposed.

Amino Acid Sequence↗
PubMed1993

Transcriptional and post-transcriptional mechanisms are involved in the absence of CD4 surface expression in two HIV-1 chronically infected T cell lines.

In vivo infection of human T cell lymphocytes by HIV-1 is mediated by the specific binding of the HIV-1 envelope glycoprotein gp120 to the T cell CD4 receptor. One of the post-infection events observed in vivo is the progressive loss of CD4+ T cells. One possible mechanism is the production of infected T cells which are lacking in surface expression of the CD4 receptor protein. We have analysed this possibility utilizing the two HIV-1 chronically-infected CD4- cell lines, 8E5 and ACH-2, both of which are derived from a CD4+ parental strain (A3.01) after HIV-1 infection. In each cell (8E5 and ACH-2) the loss of CD4 surface expression was found to occur by different mechanisms. In ACH-2 cells, neither CD4 protein nor the 3 kb CD4 RNA transcript could be detected. However, treatment of ACH-2 cells with cycloheximide elicited production of the 3 kb transcript suggesting the possibility for a repressor protein(s) to act at the level of transcription and/or stability of the 3 kb mRNA. In contrast, in 8E5 cells the level of the 3 kb CD4 RNA was comparable with that found in the CD4+ A3.01 parental strain. Analysis of the 8E5 strain revealed the presence of a CD4- gp160 bimolecular protein complex sequestered internally in the rough endoplasmic reticulum (RER). Finally, the protein tyrosine kinase p56lck, normally associated with the cellular membrane, appeared to be linked to the RER and bound to the CD4- gp160 proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Correlation between up-regulation of lymphokine mRNA and down-regulation of TcR, CD4, CD8 and lck mRNA as shown by the effect of CsA on activated T lymphocytes.

Full activation of different T cell populations via the TcR/CD3 complex leads to transient expression of lymphokine mRNA and to transient and specific down-modulation of TcR, CD4, CD8 and p56lck mRNA (Multi-Receptor Complex or MRC mRNA). This transient down-modulation is due to both a decrease in transcription and stability of these mRNA and is temporally and quantitatively related to lymphokine mRNA induction. We showed that cyclosporin A (CsA), which blocks lymphokine expression also inhibits MRC mRNA down-modulation at the transcriptional level, and does not affect mRNA stability. The fact that CsA inhibits both lymphokine expression and MRC mRNA down-modulation at transcriptional level supports a model in which similar signals trigger the inverse regulation of these two sets of genes via identical transcriptional factors.

Blotting, Northern↗
PubMed1992

Suboptimal and optimal activation signals modulate differently the expression of HIV-1 and cytokine genes.

Expression of HIV-1 and cytokine genes was investigated in chronically infected lymphocytic and promonocytic cell lines. As in normal human peripheral blood lymphocytes (PBL), a suboptimal activation signal with phorbol myristate acetate (PMA) did not trigger significant cytokine expression, whereas optimal activation signal (PMA + ionomycin) did. In contrast, a suboptimal activation was sufficient to up-regulate expression of HIV transcripts with kinetics similar to that observed in cells infected de novo by HIV. The level of HIV RNA in the promonocytic line was very low and markedly delayed when compared to the lymphocytic lines. We concluded that HIV induction required weaker activation signals than cytokine induction and that kinetics and level of HIV expression were not modified by induction of these cytokines. However, HIV expression appeared to alter the regulation of genes involved in proliferation and functional differentiation such as a decreased expression of IL-2 and IL-2R alpha and an increased expression of IFN gamma and TNF alpha mRNA.

Antigens, CD↗
PubMed1992

Functional tolerance of the human immunodeficiency virus type 1 envelope signal peptide to mutations in the amino-terminal and hydrophobic regions.

We demonstrated that the leader sequence of the human immunodeficiency virus type 1 envelope functions as signal peptide (SP) despite low scoring in a prediction program. As expected for SP, the hydrophobic core (HC) is essential, and no other sequence could compensate for HC deletion. Contrary to other SPs, major substitutions in the HC, such as introduction of basic, polar, or alpha-helix-breaking residues, still allowed efficient translocation and glycosylation. Also, extensive deletions or substitutions of the charged residues at the N terminus had little if any inhibitory effect. This report, which is the first study of human immunodeficiency virus SP, describes the exceptional tolerance of this peptide to mutations.

Amino Acid Sequence↗
PubMed1991

The defective in vitro expression of interferon-gamma messenger RNA in rheumatoid arthritis is recovered by cycloheximide.

Circulating T lymphocytes from patients with rheumatoid arthritis (RA) were found to produce low concentrations of interferon-gamma (IFN-gamma) and express low amounts of this messenger RNA (mRNA) in response to stimulation with phytohemagglutinin (PHA). In this study, we have examined the superinduction effect of cycloheximide (CHX) on the IFN-gamma mRNA expression in PHA-stimulated T lymphocytes from nine patients with active RA compared to three healthy individuals. When CHX was added 6 hr postactivation, the expression of IFN-gamma mRNA in RA patients increased significantly at 24 and 48 hr (P less than 0.01) and reached levels similar to those observed in controls. We suggest that posttranscriptional events could play a role in the defective production of IFN-gamma observed in RA.

Arthritis, Rheumatoid↗
PubMed1991

Down-regulation of lck mRNA by T cell activation involves transcriptional and post-transcriptional mechanisms.

The p56lck tyrosine kinase is most likely to be involved in signal transduction of T lymphocyte activation. After full activation through the TcR/CD3 complex lck mRNA is transiently down-modulated. This down-modulation was due to an early decrease of both transcription and stability of the lck mRNA. To study the involvement of transcriptional and post-transcriptional factors in this regulations, we have analysed the effect of cycloheximide, a protein synthesis inhibitor, on the steady-state of the lck mRNA. Cycloheximide superinduced lck mRNA by increasing its stability, although cycloheximide concomitantly decreased lck transcription. This suggests that the constitutive level of lck mRNA observed prior to activation is controlled by transcriptional activator(s) and post-transcriptional destabilizing factor(s). Second, lck mRNA down-modulation observed after full activation was inhibited by cycloheximide. It increased lck mRNA stability whereas lck transcription remained low. Therefore, full activation might increase the synthesis and/or activity of destabilizing factor(s). Cyclosporin A also inhibited the down-modulation of lck mRNA by increasing its transcription with no effect on its stability. Since, lck mRNA down-modulation was always associated with lymphokine mRNA induction, and since CsA blocks both lymphokine transcription and lck decrease of transcription, this indicates that these genes might share common regulatory pathways leading to their inverse transcriptional regulation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Helper or cytolytic functions can be selectively induced in bifunctional T cell clones.

By using bifunctional T cell populations, we have shown in this report that elicitation of helper versus cytolytic function depends on the stimulatory signal at the membrane. Interestingly enough, the transduction of these signals is likely to be achieved via different metabolic pathways. Thus, helper function is associated with intracellular Ca2+ mobilization and PLC activation, while cytolysis can occur even in the absence of detectable levels of these second messengers. These results indicate that selective activation through the same membrane-transducing molecule may orientate T cell function through qualitatively or quantitatively different second messengers. This would be an important part of immune regulation.

Antibodies, Monoclonal↗