PubMed Health⌕ Search

Biomedical subjects

D Ganea

Publications and source records attributed to D Ganea.

At least 19 recordsLinked to original sources
PubMed1992

Immunoregulatory effects of neuropeptides. Stimulation of interleukin-2 production by substance p.

Substance P (SP), a tachykinin neuropeptide, has been previously reported to stimulate T cell proliferation, and SP receptors have been identified on subpopulations of T lymphocytes. The effect of SP on the interleukin-2 (IL-2) production has been investigated by using the murine EL-4.IL-2 and LBRM-T6G T cell lines. SP synergized with phorbol 12-myristate 13-acetate (PMA) in a dose-dependent manner to induce IL-2 production. The generated interleukin was identified as IL-2 by neutralization with a specific anti-murine IL-2 monoclonal antibody. The effect of SP was specific, since spantide and physalaemin which have affinity for SP receptors inhibited the generation of IL-2 by SP. These results provide additional evidence for the immunoregulatory role of neuropeptides, and suggest that the immunostimulatory action of SP could be mediated, at least in part, through the upregulation of IL-2 expression.

Animals↗
PubMed1987

A serine proteinase inhibitor produced by an HTLV I virus-transformed human T lymphocyte line.

A previous report from our laboratory indicated that a proteinase inhibitor is produced by rabbit T lymphocytes. We now report that a human T cell line, C91/PL, produces a proteinase inhibitor which inhibits the enzymatic activity of trypsin and kallikrein. This newly identified proteinase inhibitor (LPI 1) did not inhibit the enzymatic activity of four other serine proteinases (thrombin, plasmin, chymotrypsin, or pancreatic elastase), a thiol proteinase (papain), or a carboxyl proteinase (pepsin). Active synthesis of LPI 1 by the C91/PL cell line was shown by the appearance of similar levels of inhibitory activity in sequential cell supernatants, lack of appearance of inhibitor in supernatants of cells killed by heat or sodium azide or of viable cells in the presence of cyclohexamide, and incorporation of a radiolabeled amino acid into newly synthesized inhibitor. Although both the inhibitor of rabbit origin and of human origin are proteins produced by T cells and have similar inhibitory specificity, important differences were observed: LPI 1 is sensitive to boiling and the two inhibitors migrate differently upon electrophoresis in substrate-containing polyacrylamide gel. Furthermore, LPI 1 was produced by a cell line of the T4 phenotype which had been established by in vitro viral transformation of human cord blood lymphocytes with HTLV 1 whereas the inhibitor of rabbit origin was produced by normal splenic T cells. Three other human T cell lines of the T4 phenotype, MOLT-13, KE-37, and HPB-ALL, from patients with acute lymphoblastic leukemia did not produce a proteinase inhibitor. Thus, the production of proteinase inhibitors does not appear to be a general characteristic of human T cell lines nor of the T4 subset. Proteinase inhibitors produced by T cells may have an immunoregulatory role in proteinase-mediated physiological processes.

Aprotinin↗
PubMed1987

Repair of single-stranded DNA nicks, gaps, and loops in mammalian cells.

We studied the ability of mammalian cells to repair single-stranded nicks, gaps, and loops in DNA duplexes. Heteroduplexes prepared from derivatives of the shuttle vector pSV2neo were introduced into monkey COS cells. After replication, the plasmids were recovered and used to transform Escherichia coli. Plasmid DNA from the recovered colonies was tested for repair at each of six different sites. We observed that mammalian cells are capable of repairing single-stranded gaps and free single-stranded ends most efficiently. Regions containing twin loops were recognized, and one of the loops was excised. Portions of the molecules containing small single loops were also repaired. Markers which were 58 nucleotides apart were corepaired with nearly 100% efficiency, while markers which were 1,000 nucleotides or more apart were never corepaired. The mechanisms involved in heteroduplex repair in mammalian cells seem to be similar to those involved in repairing DNA lesions caused by physical and chemical agents.

Animals↗
PubMed1987

Characterization of an ATP-dependent DNA strand transferase from human cells.

We have characterized an enzymatic activity from human cell nuclei which is capable of catalyzing strand exchange between homologous DNA sequences. The strand exchange activity was Mg2+ dependent and required ATP hydrolysis. In addition, it was capable of promoting reannealing of homologous DNA sequences and could form nucleoprotein networks in a fashion reminiscent of purified bacterial RecA protein. Using an in vitro recombination assay, we also showed that the strand exchange activity was biologically important. The factor(s) responsible for the activity has been partially purified.

Adenosine Triphosphatases↗
PubMed1986

Transcription termination within the Escherichia coli origin of DNA replication, oriC.

Initiation of DNA replication from the Escherichia coli origin, oriC, is dependent on an RNA polymerase-mediated transcription event. The function of this RNA synthetic event in initiation, however, remains obscure. Since control of the synthesis of this RNA could serve a key role in the overall initiation process, transcription regulatory sites within and near oriC were identified using the galK fusion vector system. Our results confirm the existence of a transcription termination signal within oriC, first identified by Hansen et al. (1981), for the 16 kd transcript that is transcribed counterclockwise towards oriC. Termination is shown to be 92% efficient. A similar approach led to the detection of transcription termination within the chromosomal replication origin of Klebsiella pneumoniae. Approximately 50% of the E. coli 16 kd transcripts appear to terminate before reaching oriC between the XhoI (+416 bp) and the HindIII (+243 bp) sites. The predominant 3' ends of RNA that enter oriC, as determined by SI nuclease mapping, were located at positions +20 +/- 2, +23 +/- 2, +37, +39, +52, +66, +92, and +107. These termination sites, which map cl to RNA . DNA junctions identified by Kohara et al. (1985), appear as triplets and quadruplets. The E. coli oriC Pori-L promoter described in in vitro transcription studies by Lother and Messer (1981) was not detected in this study in either wildtype cells or isogenic dnaA mutants at the nonpermissive temperature. A new promoter activity, Pori-R1, was identified within the E. coli origin in the clockwise direction.

DNA Replication↗
PubMed1986

A low molecular weight proteinase inhibitor produced by T lymphocytes.

A low molecular weight (MW) proteinase inhibitor, between 6500 and 21,500 MW, appeared in the supernatant of rabbit spleen cells cultured at high density for 24 hr. The inhibitor inhibited the enzymatic activity of trypsin for both a high MW natural substrate, fibrinogen, and for a low MW artificial substrate, Chromozym TRY. The low MW proteinase inhibitor is protein in nature and is different, in terms of specificity for enzymes, MW and sensitivity to different physical or chemical treatments, from aprotinin, a low MW proteinase inhibitor (6500 MW) of bovine origin, and from the soybean trypsin inhibitor, a relatively high MW proteinase inhibitor (21,500 MW). The inhibitor was found in the supernatant of purified T cells but not B cells, and its production was increased in the presence of an optimal concentration of Con A. The possibility that this proteinase inhibitor has a role in the regulation of trypsin-like proteinases involved to the immune response remains to be investigated.

Animals↗
PubMed1985

Allogeneic lymphocyte stimulation in rabbits: induction of a low MW inhibitor for trypsin and for a concurrently induced alpha-macroglobulin-proteinase complex.

We have shown previously that the i.v. inoculation of allogeneic lymph node cells in rabbits induces the appearance in the serum of an alpha M-serine proteinase complex which behaves in an Ig-turnover assay as any polyclonal B-cell activator (PBA), and that this PBA activity is due to the enzyme. Here, we show that the allogeneic stimulation also induces the appearance in the low molecular weight fraction of the serum (1000-110,000 MW) of an inhibitor which blocks the PBA activity of the complex without affecting the PBA activity of LPS or dextran sulphate. The inhibitor blocked the ability of the enzyme associated with alpha M to degrade Chromozym TRY, a low MW trypsin substrate. The inhibitor also blocked the enzymatic activity of trypsin for large as well as for low MW substrates. Thus, allogeneic stimulation in vivo results in the production, not only of an alpha M-proteinase complex, but also of an inhibitor for this proteinase as well as for trypsin. The appearance of the inhibitor, along with the alpha M-serine proteinase complex as a result of allogeneic stimulation in rabbits, is of interest since a similar alpha M-serine proteinase complex and inhibitor may appear in the serum of patients with rheumatoid arthritis.

Animals↗
PubMed1984

Degradation of a chromogenic substrate by alpha 2-macroglobulin from plasma of patients with rheumatoid arthritis.

We have shown previously that serum from patients with rheumatoid arthritis (RA) contains a polyclonal B cell activator that is associated with alpha 2-macroglobulin (alpha 2M). Some biologic effects of this activator appear to be due to a trypsin-like protease attached to alpha 2M. Therefore, in the present study, we used an anti-alpha 2M antibody solid-phase assay, with Chromozym-Try as a substrate, to determine the level of alpha 2M-protease complexes in plasma alpha 2M. We found higher levels of these complexes in RA patients than in 2 control groups. Since alpha 2M-protease complexes have been shown to induce RA-like inflammation in experimental animals and to be produced by lymphoid cells, we speculate that they may be involved in the pathogenesis of RA. However, the role of the other cells or enzyme systems in the formation of these complexes has not yet been ruled out. Results of these investigations could lead to another link between activation of the immune system and joint inflammation.

Adult↗
PubMed1982

The effect of protease inhibitors on the polyclonal B cell activator from the serum of patients with rheumatoid arthritis.

It has been reported that polyclonal B cell stimulation results in formation of autoantibodies and immune complexes. We have previously reported that a polyclonal B cell activator (PBA) associated with alpha 2-macroglobulin (alpha 2M) is present in the serum of patients with rheumatoid arthritis and related diseases. Here we studied the possibility that patient alpha 2M (Pt-alpha 2M) carries a trypsin-like protease responsible for the PBA activity. This activity was determined by the Ig-turnover assay developed in our laboratories. The small molecular weight protease inhibitors, aprotinin (Trasylol, Bayer) and phenylmethylsulfonylfluoride (PMSF), and the large molecular weight soybean trypsin inhibitor (SBTI) were used. These inhibitors did not affect the PBA activity of dextran sulfate of LPS. However, as expected, trypsin had a PBA-activity which was blocked by all of the above mentioned inhibitors. A trypsin-normal alpha 2M complex (Tr-N alpha 2M) and PBA activity which was inhibited by PMSF or aprotinin but not by SBTI. The PBA associated with Pt-alpha 2M was also inhibited by PMSF or aprotinin but not by SBTI. Moreover, the Tr-N alpha 2M complex and the Pt-alpha 2M, but not that from normal donors, had esterase activity for p-toluenesulfonyl-L-argininemethyl ester. These data suggest a similarity between the Pt-alpha 2M and Tr-N alpha 2M complex. Thus, we concluded that the esterolytic activity is sufficient for PBA activity, that Pt-alpha 2M has esterolytic activity and that this PBA activity can be blocked by small molecular weight protease inhibitors.

Animals↗
PubMed1981

An alpha2-macroglobulin associated factor produced by T lymphocytes which provides polyclonal stimulation of B lymphocytes to maintain the turnover of their surface Ig.

The supernatant of 'crowded' but not 'spread' rabbit spleen cell cultures contains a macroglobulin factor which behaves in an Ig-turnover assay as any T-independent antigen or polyclonal B-cell activator (PBA). In the supernatants of crowded rabbit lymphoid cell cultures prepared in serum free medium, the factor was found to be associated entirely with the alpha-macroglobulin (alpha M) fraction (alpha 1 + alpha 2). This alpha M was most probably actively secreted by the lymphocytes because: (i) sequential supernatants obtained in serum free medium of crowded cultures contained equal amounts of alpha M as well as equal PBA activity; (ii) the alpha M became labelled when the cells were grown in medium containing a radioactive amino acid. Macrophages were not required for the production of PBA. PBA was not produced when either crowded B or T cells were cultured alone but only when they were cultured together. Purified T cells were not triggered by any plant lectin to produce PBA. By use of anti-alpha 2M allotype antibodies and B and T cells from different rabbits, the PBA was shown to have the allotype of the T-cell donor. The PBA was associated with rabbit alpha 2M but not alpha 1M. We concluded that upon close contact, B cells stimulate T cells to produce a PBA associated with alpha 2M.

Animals↗
PubMedDate not supplied

[Ontogeny of the immune response in mice. I. Presence of IgG and alpha fetoprotein in the body fluids of mice of various ages].

Alpha protein and IgG were determined by radial immunodiffusion in Swiss mice, in the amniotic fluid, milk and serum of the mice at different ages (fetus, neonates, at the age of 5, 10, 15, 20, 25, 30, 35 and 40 days and adults). The highest alpha-protein concentrations were found in the fetal serum (0.20 mg/ml) ; after birth serum levels rapidly fell and at 20 days could no longer be detected ; it was present in the amniotic fluid and milk collected within the first 24 hours after birth. In contrast, IgG was found in small concentrations in the fetal serum (0.60 mg/ml) but increased with age after birth. This immunoglobulin was present in the amniotic fluid and mothers' milk for 15 days. The significance of the results is discussed.

Age Factors↗