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Biomedical subjects

M Revel

Publications and source records attributed to M Revel.

At least 163 records · Page 9Linked to original sources
PubMed1988

Eye-head coupling in humans. I. Simultaneous recording of isolated motor units in dorsal neck muscles and horizontal eye movements.

A tonic coupling between the horizontal component of eye position and dorsal neck muscle activity has been demonstrated in the cat and monkey. In order to demonstrate this synergy in humans and study its characteristics, we have measured the relation between the firing rate of individual motor unit of the splenius muscle and voluntary horizontal shifts of gaze using 5 degrees steps, in head-fixed subjects. Eye movement recording was achieved by conventional binocular electro-oculography and the activity of the right splenius muscle was recorded with Bronks coaxial bipolar electrodes inserted manually at the C4-C5 intervertebral level. The activity of 51 motor units in 10 subjects has been recorded. For all subjects, motor units firing rate increased when the gaze shifted to the ipsilateral side, and both increase in firing rate and recruitment were observed. These results demonstrate that the tonic eye head synergy is also present in man.

Action Potentials↗
PubMed1988

Interferon-beta induced remission in a hairy cell leukemia patient resistant to interferon-alpha.

Two patients with advanced hairy cell leukemia and pancytopenia responded successfully to intramuscular injections of recombinant interferon-beta, with normalisation of blood counts. One of the patients had developed resistance to interferon-alpha. The in-vivo response was predicted by in-vitro studies showing a beneficial effect of IFN-beta on erythropoiesis in cell cultures derived from these patients.

Bone Marrow↗
PubMed1988

Nucleotide sequence analysis of an Entamoeba histolytica ferredoxin gene.

A cDNA clone (subclone B) previously isolated from the human parasite Entamoeba histolytica was characterized. DNA sequence analysis of subclone B identified the DNA as that encoding apoferredoxin. E. histolytica ferredoxin cDNA contains unusually short 5' and 3' noncoding regions of 9 and 25 nucleotides, respectively. A genomic ferredoxin clone was isolated from E. histolytica DNA, and comparison of genomic and cDNA sequences revealed that the ferredoxin gene is unspliced. The deduced amino acid sequence of E. histolytica ferredoxin resembles clostridial type of ferredoxins, and shows an arrangement of cysteines characteristic for the coordination of 2[4Fe-4S] centres. Of interest is the absence of an aromatic amino acid in the N-terminal region of the protein, a feature which is conserved in clostridial ferredoxins. Southern blot analysis of three different E. histolytica strains (200:NIH, Rahman and HM-1:IMSS) demonstrated the presence of a family of at least two ferredoxin genes. One of these genes is marked by restriction length polymorphisms in different strains of E. histolytica.

Amino Acid Sequence↗
PubMed1988

Growth inhibition of human breast carcinoma and leukemia/lymphoma cell lines by recombinant interferon-beta 2.

Recombinant human interferon-beta 2 was produced in Escherichia coli by direct expression of cDNA encoding the mature protein sequence. At concentrations that stimulate DNA synthesis and growth in B-cell hybridomas and plasmacytomas, the cytokine was found to exert a strong inhibition on the growth of a number of carcinoma and leukemia/lymphoma cell lines. This antigrowth effect was observed in clonogenic assays and by measurements of cell number and thymidine incorporation in growing cultures. The effect was blocked by antibodies to a synthetic peptide from the N terminus of the molecule. Normal diploid fibroblasts were inhibited at concentrations higher than those needed for breast carcinoma cells.

Breast Neoplasms↗
PubMed1988

Interferon-beta 2 (BSF-2) mRNA is expressed in human monocytes.

We previously have reported the presence of interferon-beta 2 (IFN-beta 2) mRNA in PHA-stimulated human peripheral blood leukocytes (PBL), as well as in nonstimulated cells, although at a lower level. The IFN-beta 2 cloned from a leukocyte library appeared to be similar to that of the fibroblast IFN-beta 2 gene first described in fibroblasts. To assess the nature of the cell population in which the synthesis of IFN-beta 2 takes place, PBL were fractionated in adherent and nonadherent cells. The antiviral activity of the culture supernatants of adherent cells was characterized as the IFN-beta type by neutralization with polyclonal antibodies raised against purified fibroblast IFN-beta 2. IFN-beta 2 mRNA was observed in enriched monocyte populations and accumulated very rapidly, peaking at 2.5 h. RNA extracted from these cultures encoded in a reticulocyte lysate a protein immunoprecipitated by the anti-IFN-beta 2 antiserum. In addition, IFN-beta 2 secreted in monocyte supernatants also was immunoprecipitated by the specific antiserum and was able to compete with the fibroblast IFN-beta 2, suggesting a strong similarity between the fibroblast and monocyte proteins.

Cell Adhesion↗
PubMed1988

Cloning of genomic DNA for tumor necrosis factor and efficient expression in CHO cells.

A genomic clone for human tumor necrosis factor (TNF-alpha) was isolated using synthetic oligonucleotide probes. The genomic DNA was cleaved to remove 5' regulatory sequences and cloned in a PSVE3 expression vector containing the SV40 early promoter. The plasmid was co-transfected with a selectable dihydrofolate reductase (DHFR) gene into DHFR-deficient Chinese hamster ovary cells. Efficient expression of TNF mRNA was established by Northern analysis. Expression of TNF protein was assayed for by cytotoxic activity for cycloheximide-treated SV80 fibroblasts. Selected transfected cultures secreted as much as 50,000 units of TNF activity/ml of culture medium. Synthesis of TNF protein was confirmed by immunofluorescence of transfected cells with a monoclonal antibody to TNF and immunoprecipitation of 17 kD protein from transfected CHO culture supernates. The efficient expression of TNF from genomic DNA in transfected mammalian cells may be advantageous for biologic uses.

Animals↗
PubMed1988

The myeloid blood cell differentiation-inducing protein MGI-2A is interleukin-6.

The mouse myeloid blood cell differentiation-inducing protein, macrophage and granulocyte inducer, type 2A (MGI-2A), was purified, and the amino acid sequence of a CNBr cleavage peptide (22 residues) was determined. This amino acid sequence is identical to the sequence found in positions 73 to 94 of mouse interleukin-6 (IL-6). Recombinant mouse IL-6 protein induces differentiation of mouse myeloid leukemic cells that are induced to differentiation by MGI-2, and monoclonal antimouse-MGI-2 antibody, which neutralizes MGI-2, also completely neutralizes this IL-6-induced differentiation. These results show that the major type of mouse myeloid differentiation-inducing protein (MGI-2A) and IL-6 are very similar and most likely identical proteins. Recombinant human IL-6 (also called interferon-beta 2 or B-cell differentiation factor), which shows only a 41% similarity to mouse IL-6, has 11 identical amino acid residues out of the 22 in the mouse MGI-2A peptide and also induces differentiation of the same myeloid leukemic cells.

Amino Acid Sequence↗
PubMed1987

Reduced production of tumor necrosis factor by mononuclear cells in hairy cell leukemia patients and improvement following interferon therapy.

In 16 patients with hairy cell leukemia (HCL) there was a marked reduction in the production of cytotoxins (CTXs) by peripheral blood mononuclear leukocytes in response to stimulation in vitro by phytohemagglutinin (PHA), 4 beta-phorbol-12-myristate-13-acetate (PMA), or Sendai virus. CTX yields of 23.5 +/- 21.5 U/ml, 15 +/- 18 U/ml, and 12.1 +/- 12.1 U/ml were obtained in response to PHA, PMA, and Sendai virus, respectively, as compared with corresponding yields of 207.3 +/- 93.1, 154 +/- 37.4, and 205.2 +/- 62.4 in healthy controls. The extent of reduced production of CTXs appeared to be correlated with the severity of the disease. Systemic interferon (IFN) administered to four patients caused CTX production to improve in response to PHA (147.5 +/- 55.1 U/ml compared with pretreatment values of 14.1 +/- 6 U/ml, P less than 0.05). However, CTX production in response to Sendai virus remained low. The extent to which CTX production by hairy cell leukemia mononuclear cells was reduced was proportionate to the observed decrease in monocyte counts. However, the degree to which CTX production improved after IFN treatment was significantly greater than the observed increase in monocyte counts. The major CTX induced by PHA in mononuclear cells of healthy donors and of IFN-treated HCL patients was identified as tumor necrosis factor-alpha.

Adult↗
PubMed1987

The human interferon-gamma receptor. Purification, characterization, and preparation of antibodies.

The receptor for human interferon-gamma (IFN-gamma) was purified from foreskin fibroblasts. Triton X-100 extracts obtained from either intact cells or membrane preparations were passed through an immobilized interferon-gamma column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of eluted fractions revealed a major band of Mr = 95,000 and minor bands of Mr = 80,000 and 60,000. Further purification was obtained by steric exclusion and by lectin chromatography. The purified receptor retained the ability to bind 125I-IFN-gamma with a Kd of 2.2 X 10(-10) M, a value close to that obtained with intact fibroblasts (5 X 10(-10) M). A complex of Mr = 105,000-125,000 was visualized by immunoprecipitation of 125I-IFN-gamma cross-linked to the purified receptor followed by SDS-PAGE and autoradiography. A similar complex was obtained when 125I-IFN-gamma was cross-linked to intact cells. Immunization of mice with the excised SDS-PAGE band of Mr = 95,000 elicited antibodies that blocked the antiviral activity of IFN-gamma and immunoprecipitated the cross-linked complex of 125I-IFN-gamma and its receptor.

Antibodies↗
PubMed1987

Four different forms of interferon-induced 2',5'-oligo(A) synthetase identified by immunoblotting in human cells.

Antibodies against synthetic peptides derived from the cDNA sequence of interferon-induced 2',5'-oligo(A) synthetase, and which immunoprecipitate the native enzyme activity, were found to detect multiple enzyme forms in denaturing electrophoretic immunoblots. In some human cell lines, four different interferon-induced proteins of 40, 46, 67, and 100 kDa were found to react with the same peptide antibodies. Each isolated form was shown to have 2',5'-oligo(A) synthetase activity, but the dependence on double-stranded RNA was markedly different for activation of the individual enzymes. The four enzyme forms also differ in their intracellular localization, on microsomes (100 kDa), in nuclei (67, 46, 40 kDa), and on membrane structures (67 kDa). Plasma membranes from interferon-treated Daudi lymphoblastoid cells are highly enriched in the 67-kDa 2',5'-oligo(A) synthetase form. The 2',5'-oligo(A) synthetase activity induced by interferons in human cells appears, therefore, as a complex multienzyme system.

2',5'-Oligoadenylate Synthetase↗
PubMed1987

Interferons: cytokines in autoimmunity.

The presence of circulating interferons in the blood of patients with autoimmune diseases and the acquired immune deficiency syndrome (AIDS) raises the question of their possible pathogenetic or defence functions. Interferons control levels of HLA class I and II antigens on cells and can activate or inhibit immune killer cell activities. Tumour necrosis factors (TNF) and interleukin 1 induce a new autocrine species of interferon known as IFN-beta-2 whose gene has been cloned, sequenced and expressed. This IFN mediates the increase in HLA expression caused by TNF as well as the antiviral activity of this cytotoxin.

Autoimmune Diseases↗
PubMed1987

Entamoeba histolytica: cloning and characterization of actin cDNA.

In order to study gene expression in the human parasite Entamoeba histolytica, a cDNA library of E. histolytica strain 200:NIH was constructed using the phage vector lambda gt10. Three cDNA clones (A, B and C) were selected for further analysis. Each of the three clones hybridized to a distinct mRNA. Two of these mRNAs were translated in vitro after hybrid selection, and yielded distinct translation products. One of these mRNAs, selected by hybridization to clone A, encodes the most abundantly expressed protein in E. histolytica. DNA sequence analysis of this cDNA clone identified the DNA as that encoding actin. The deduced amino acid sequence of E. histolytica actin resembles both cytoplasmic and muscle actins and has an unusual N-terminal glycine residue. We have shown that a family of actin genes is present in E. histolytica. Six different E. histolytica actin clones were obtained from a lambda gt10 genomic library using subcloned cDNA probes. Southern analysis of three different E. histolytica strains (200:NIH, Rhaman, and HM-1:IMSS) revealed at least four different actin genes. Strain HM-1:IMSS, however, differs by the presence of an additional actin gene.

Actins↗
PubMed1987

Interferons regulate the in vitro differentiation of multilineage lympho-myeloid stem cells in hairy cell leukemia.

In vitro 14-day cultures of peripheral blood mononuclear cells from hairy cell leukemia patients consistently showed the presence of hematopoietic stem cells giving rise to multilineage colonies containing a high proportion of lymphoid cells associated with the myeloid and erythroid progenitors. These stem cells are not the hairy cells but appear to be pluripotent lymphomyeloid primitive stem cells persisting in this leukemia. Interferon alpha c or beta 1 did not inhibit the growth of these colonies, as they did the growth of colonies of normal hematopoietic progenitors, but markedly decreased the ratio of lymphoid to myelomonocytic cells, by increasing the formation of monocytes and other nonlymphoid cell types in these multilineage colonies. Interferon gamma did not have the same effects on differentiation.

Aged↗
PubMed1987

Interferon-responsive regulatory elements in the promoter of the human 2',5'-oligo(A) synthetase gene.

The interferon (IFN)-activated human 2',5'-oligo(A) synthetase E gene contains 11 RNA starts and lacks TATA and CAAT signals. DNA sequences around the promoter make the expression of the chloramphenicol acetyltransferase gene (CAT) inducible over 20-fold by IFN. A 72-base-pair segment (E-IRS) immediately upstream of the RNA starts was defined as being required for IFN-activated expression of the E-gene promoter-CAT constructs and acts in a position-independent manner. It also confers IFN-activated enhancement to the herpes simplex virus thymidine kinase promoter. On this promoter, the 5' part of the E-IRS functions as a constitutive enhancer, while the last 16 base pairs of the E-IRS is sufficient to give IFN-induced expression. On the E-gene promoter, the constitutive enhancer and the IFN-activated sequence are both needed but can be separated. In addition, promoter competition experiments indicate a third regulatory region which helps to repress expression of the E gene in uninduced cells.

2',5'-Oligoadenylate Synthetase↗