PubMed Health⌕ Search

Biomedical subjects

P De Somer

Publications and source records attributed to P De Somer.

At least 19 recordsLinked to original sources

Prophylaxis in cardiac surgery. A controlled randomized comparison between cefazolin and cefuroxime.

In a prospective randomized two center trial, short-term prophylaxis with cefuroxime (CFX) in 189 patients was compared with cefazolin (CFZ) in 196 patients submitted to elective cardiac surgery. A total of 3 g was administered over 24 h in both groups. One major adverse reaction with CFX was noted. Patients were prospectively screened by infectious disease nurses for surgical wound and secondary infections. Sternal wound infections occurred in eight patients treated with CFX and all were minor. One patient from this group eventually died of infectious causes. In the CFZ-treated patients two major and six minor wound infections occurred requiring extensive debridement in two. Secondary infections occurred less frequently in the CFX group (13.2 per 100) than in the CFZ group (16.8 per 100) with two infection-related deaths in the CFX and one in the CFZ group. The most commonly identified organisms were Staphylococcus aureus and a variety of gram-negative organisms. No major differences were observed between the CFX and CFZ groups. Short-term administration of 3 g CFZ or CFX in this study could not demonstrate the advantage of one of the antibiotics used over the other in terms of clinical outcome, incidence or site of infection or organisms identified. The 24 h administration of 3 g CFZ or CFX provided suboptimal prophylaxis for wound infection or secondary infections in patients undergoing elective open heart surgery.

Adult↗

The inhibition of endotoxin-induced local inflammation by LDH virus or LDH virus-infected tumors is mediated by interferon.

The footpad swelling reaction induced by local injection of S. marcescens lipopolysaccharide was found to be inhibited in mice given a transplantable tumor (TA3) or cell-free ascitic fluid from tumor-bearing mice. The tumor was shown to contain LDH virus, which is known to cause inapparent persistent infections in mice. Monoclonal antibodies directed against protein VP3 of the LDH virus could partially abrogate the anti-inflammatory effect of the TA3-ascitic fluid, and, conversely, the anti-inflammatory effect could be obtained by LDH virus isolated from the tumor and reproduced by serial passage of cell-free fluids. Inhibition of the footpad reaction was seen in the acute but not in the chronic phase of LDH virus infection, suggesting that the anti-inflammatory effect might be due to endogenous interferon (IFN) which, similarly, was only detectable in the acute phase. Newcastle disease virus, another potent interferon inducer, had a similar inhibitory effect on the footpad reactivity. Moreover, the inhibitory effect of LDH virus infection could partially be abrogated by administration of a polyclonal antibody directed against murine IFN-alpha,beta. Finally, passively administered natural murine IFN-alpha,beta or recombinant murine IFN-alpha 1 (but not recombinant murine IFN-beta) was found to cause inhibition of the footpad reaction. Since Gram-negative bacteria and their lipopolysaccharides have the ability to induce a systemic interferon response, our findings suggest that this interferon may play a modulatory role in local inflammation caused by these bacteria. Our findings also open a new perspective for interferon therapy of certain inflammatory reactions to bacterial infections.

Animals↗

Influence of carbohydrate side chains on activity of tissue-type plasminogen activator.

When messenger RNA (mRNA) from both untreated and phorbol ester-treated melanoma cells is translated in simple reticulocyte lysates, tissue-type plasminogen activator can be immunoprecipitated by an affinity-purified antibody as a approximately 52,000 mol wt protein, with no detectable biological (plasminogen activating) activity. When the reticulocyte lysate system is supplemented with a preparation of microsomal membranes, biological activity becomes detectable and a 63,000 mol wt protein can be immunoprecipitated with the same antibody. Furthermore, when natural tissue-type plasminogen activator (mol wt approximately equal to 70,000) is incubated with different glycosidases, distinct alterations in the electrophoretic mobility of the molecules are observed, together with alterations in the level of biological activity. While treatment with neuraminidase and beta-galactosidase caused decreases in activity, alpha-mannosidase caused an increase. These results suggest that the carbohydrate part of the molecule can influence its biological behavior.

Amides↗

Cloning of cDNA coding for human tissue-type plasminogen activator and its expression in Escherichia coli.

cDNA clones of the mRNA coding for tissue-type plasminogen activator (t-PA) have been obtained and their nucleotide sequences compared to those reported previously. A gene coding for t-PA has been reconstructed and inserted into vectors for expression in prokaryotic cells. Relatively high levels of t-PA accumulated in inclusion bodies in Escherichia coli containing an optimized expression plasmid, but only a small proportion of the insoluble protein was recovered as active enzyme using a variety of solubilization procedures.

Amino Acid Sequence↗

Molecular cloning of murine interferon gamma (MuIFN-gamma) cDNA and its expression in heterologous mammalian cells.

A complete cDNA clone of murine interferon-gamma (MuIFN-gamma) was obtained by recombining two appropriate segments from partial cDNA clones originally identified by colony hybridization with rat IFN-gamma chromosomal gene fragments as probes. An expression vector was constructed in which the cDNA was placed under control of the SV40 early promoter. Transient expression of MuIFN-gamma was obtained by transformation of COS-1 cells. Subsequently, this interferon expression unit was linked to a vector containing a dihydrofolate reductase (DHFR) modular gene and used to transform DHFR(-)-CHO cells. Cell clones were selected that constitutively produce an interferon activity which by several criteria was found to be indistinguishable from natural, splenocyte-derived MuIFN-gamma.

Animals↗

Stimulation of fibroblast interferon production by a 22K protein from human leukocytes.

We have studied the appearance of human interferon-beta (HuIFN-beta) as well as its mRNA in cells treated with a protein, 22K factor, isolated from the culture supernatant of mitogen-stimulated human peripheral blood leukocytes. By itself 22K was found to be unable to induce production of significant amounts of HuIFN-beta protein. However, when aided by treatment with cycloheximide or cycloheximide and actinomycin D (superinduction), 22K caused increases in production ranging from 3- to 20-fold, depending on the cells (diploid or MG-63 osteosarcoma) and the induction schedule. Cells treated with 22K alone produced small amounts of HuIFN-beta mRNA, which was only detectable with a highly sensitive method. In combination with cycloheximide, 22K induced levels of mRNA detectable with less sensitive methods as well. These experiments provide further support for the concept that the antiviral activity of 22K is mediated by its ability to stimulate transcription of the HuIFN-beta gene in cells.

Blood Proteins↗

Effects of 12-O-tetradecanoylphorbol 13-acetate on the production of mRNAs for human tissue-type plasminogen activator.

The mRNA for human (tissue type) plasminogen activator from a human melanoma cell line (Bowes) was investigated in different translation systems. After translation of poly(A)-rich RNA in Xenopus oocytes a biologically active plasminogen activator was obtained. Sodium dodecyl sulphate/polyacrylamide gel electrophoresis of the secreted translation products revealed a protein band precipitable with affinospecific antibody and migrating at the same position (apparent molecular mass of approximately 70000 Da) as the native melanoma cell product. Translation in rabbit reticulocyte lysate yielded an immunoprecipitable band migrating at position corresponding to a molecular mass of 52000 Da. Addition of 12-O-tetradecanoylphorbol 13-acetate to the cell cultures resulted in increased production of plasminogen activator. Concomittantly more poly(A)-rich RNA could be extracted from the cells and this RNA was more effectively translated by oocytes into biologically active plasminogen activator. Translation of poly(A)-rich RNA from phorbol-ester-treated cells in the reticulocyte lysate system yielded the 52000-Da protein also seen with RNA from untreated cells. However, in addition a prominent protein band of apparent molecular mass of 48000 Da was detectable. Its intensity increased with increasing doses of tetradecanoylphorbol acetate. This phorbol-ester-induced protein was not precipitable with the affinospecific antibody against plasminogen activator.

Animals↗

An interferon-beta-like or interferon-inducing protein released by mitogen-stimulated human leukocytes.

Human peripheral blood leukocytes were treated with concanavalin A (Con A) to produce interferon gamma (HuIFN-gamma). On gel filtration this interferon eluted as a protein with a molecular weight of 45000. In addition to this, the culture supernatant contained an interferon-like protein of apparent molecular weight 22000 (22K factor). The antiviral activity of this protein was neutralizable by a highly specific antibody to HuIFN-beta. Yet, the 22K factor differed from classical HuIFN-beta in several characteristics: lack of activity on certain homologous and heterologous cells which are sensitive to HuIFN-beta; lack of affinity for zinc-chelate and Con A-Sepharose columns; failure to bind to an anti-HuIFN-beta antibody column. Moreover, a specific antiserum raised against the 22K factor did not neutralize HuIFN-beta. Two alternative explanations of these findings are proposed: (i) the 22K factor is an interferon whose molecular structure resembles that of the known HuIFN-beta but it is not identical to it, or (ii) the 22K factor is not an interferon but a protein that can induce the production of HuIFN-beta in certain lines of fibroblastoid cells.

Concanavalin A↗

Interferon induced in human leukocytes by concanavalin A: isolation and characterization of gamma- and beta-type components.

Interferon (IFN) was induced in suspensions of fresh human leukocytes by incubation with concanavalin A (Con A). The crude supernatant was concentrated and partially purified by adsorption to silicic acid and elution with an ethylene glycol (EG)-containing buffer. Th EG eluate was shown to contain two antivirally active components (tentatively called 22K), separable from each other by gel filtration. The 45K component was strictly species specific, relatively sensitive to acid (pH 2) and poorly neutralized by anti-human IFN-beta (HuIFN-beta) antibody. In all probability, it predominantly contained (a) molecular variant(s) of human gamma-type IFN (HuIFN-gamma ). The 22K component was acid resistant and serologically indistinguishable from HuIFN-beta prepared from fibroblasts. However, in contrast to the latter, it had little activity on bovine kidney cells and no activity on human HEp-2 and monkey Vero cells. A preparation with the same properties was obtained by substituting glycine buffer (pH 2) for EG in the elution of Con A-induced IFN from silicic acid. This IFN failed to adsorb to a zinc chelate column, while HuIFN-beta from fibroblasts can easily be purified by affinity chromatography on this type of column. It was concluded that the Con A-induced IFN contained an acid-resistant component of apparent molecular weight 22000 serologically related to classical HuIFN-beta but differing by certain physicochemical and biological criteria.

Animals↗

The preparation of antibodies directed against human immune interferon.

Antisera against human immune interferon (HuIFN-gamma) were prepared by immunization of rabbits and a goat with antigens of different degrees of purity: a) crude supernatant from concanavalin A-stimulated human leukocytes; b) a preparation partially purified by adsorption to controlled pore glass; and c) pooled fractions (molecular weight - 45,000) obtained by gel filtration and corresponding to the peak of HuIFN-gamma. Antisera with a relatively high titer were obtained in animals immunized with the latter two antigens. The sera were specific for HuIFN-gamma in that they failed to neutralize preparations of HuIFN-alpha and and HuIFN-beta. From the time course of the antibody titers in each animal it seemed that frequent boosters within a short time interval led to a decrease rather than an increase in neutralizing activity of the sera.

Animals↗

(E)-5-(2-bromovinyl)-2'-Deoxyuridine in the treatment of experimental herpes simplex keratitis.

IDU (5-iodo-2'-deoxyuridine), BVDU [(E)-5-(2-bromovinyl)-2'-deoxyuridine] and placebo ointments were studied for their effects on experimental herpes simplex (type 1) keratoconjuncitivitis in rabbits. When treatment was begun 65 h after virus inoculation, both BVDU and IDU prevented development of keratitis. Both BVDU and IDU were also effective in suppressing the severity of conjunctivitis, and in this respect, BVDU proved significantly better than IDU. When treatment was started 110 h after virus inoculation, BVDU proved significantly better than IDU in promoting healing of established keratitis.

Animals↗