Search PubMed⌕ Search

Biomedical subjects

R Mayer

Publications and source records attributed to R Mayer.

At least 181 records · Page 10Linked to original sources
PubMed1989

IL-3 induces differentiation of bone marrow precursor cells to osteoclast-like cells.

IL-3, a cytokine with hematopoietic differentiating capability, induced murine bone marrow cells to differentiate into cells resembling osteoclasts. The cells resulting from treatment with IL-3 were multi-nucleated and demonstrated tartrate-resistant acid-phosphatase activity, as do resident osteoclasts found in bone. IL-3-induced osteoclast-like cell development in the absence of serum-derived vitamin D metabolites, and a mAb that inhibited IL-3-induced proliferation of an addicted cell line also inhibited the development of osteoclasts in the presence of IL-3. The same Ab had no effect on 1 alpha, 25-dihydroxyvitamin D3-induced differentiation of osteoclasts. This newly described function of IL-3 may indicate a role for activated T cells in the bone resorption seen with rheumatoid arthritis.

Acid Phosphatase↗
PubMed1989

Origin of the autoreactive anti-type II collagen response. II. Specificities, antibody isotypes and usage of V gene families of anti-type II collagen B cells.

Autoantibodies play an important role in the pathogenesis of type II collagen-induced arthritis in mice. We have earlier reported a high frequency of cells producing anti-CII autoantibodies and a low frequency of cells producing multispecific antibodies, in regional lymph nodes 9 to 11 days after primary immunization with CII. It is shown here that anti-CII antibodies produced during primary immune response are IgG-antibodies mainly of IgG2a, IgG1 and IgG2b subclasses while IgM antibodies dominate primary responses elicited by OVA and denatured CII as analyzed with a large panel of hybridomas. Anti-CII antibodies generated during the primary response recognize at least five different epitopes on the CII molecule. The specificities of these antibodies for various epitopes result from combinational association of products encoded by genes derived from various VH and VK families and/or by the occurrence of somatic mutations. It is suggested that the primary anti-CII autoantibody response involves activation of memory B cells and is in this aspect different from the origin of "natural" autoantibodies.

Animals↗
PubMed1989

Purification and identification of a neutral endopeptidase in Plasmodium falciparum schizonts and merozoites.

An endopeptidase specific to the Plasmodium falciparum erythrocytic schizont stage and to free merozoites was detected using the fluorogenic GlcA-Val-Leu-Gly-Lys(or Arg)-AEC substrate. The enzyme was purified by high performance liquid chromatography (HPLC); its optimal activity was around pH 7.5 and its isoelectric point was 4.4. The molecular weight of the enzyme was about 68,000, as demonstrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. The endopeptidase was strongly inhibited by thiol proteinase inhibitors, leupeptin, and antipain. The possible involvement of this neutral endopeptidase in the reinvasion process is discussed.

Animals↗
PubMed1989

Muramyl dipeptide bound to poly-L-lysine substituted with mannose and gluconoyl residues as macrophage activators.

Poly-L-lysine modified with mannose derivatives, the residual cationic charges of which being neutralized by N-acylation, were synthesized and used as carriers of a macrophage activator (N-acetylmuramyl dipeptide, MDP). The influence of the acylating agent on the targeting efficiency was investigated: a hydrosolubilizing group such as a gluconoyl moiety led to very efficient carrier conjugates, while an acetyl group did not. The effect of sugar and acyl content of the polymers was assessed using these compounds as inhibitors of red blood cell agglutination by Concanavalin A. The binding and specific endocytosis of poly-L-lysine substituted with several mannose derivatives and gluconoyl residues (GlcAx-, Man(y)-PLK) have been determined by a quantitative flow cytometry analysis. MDP bound to these conjugates was much more efficient in vitro than free MDP in macrophage cytostasis assays.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Activation of clones producing self-reactive antibodies by foreign antigen and antiidiotype antibody carrying the internal image of the antigen.

Because we found in previous work that a high fraction of antibodies exhibiting various specificities bound to glutamic acid 50-tyrosine50 homopolymer (GT) and expressed pGAT cross-reactive idiotype (IdX), we studied the activation of clones producing multireactive antibodies in 1-mo-old MRL/lpr and C3H/HeJ mice bearing VHJ haplotype. The activation of such clones was studied after mice were immunized with GT in CFA, HP20 (an anti-Id MAb carrying the internal image of GT in the D region), and a synthetic peptide corresponding to the D segment of HP20. Our results indicate that immunized mice produced both GT- and self-reactive antibodies. Study of the immunochemical properties of MAb showed that they exhibit multispecific properties and bind with similar-affinity constants to GT or self-antigens such as DNA, Smith antigen (Sm), and IgG2a. An important fraction of antibodies obtained from MRL/lpr mice immunized with HP20 expressed pGAT IdX and some of these antibodies share IdX expressed on anti-DNA, Sm, and rheumatoid factor (RFs) antibodies. The hybridomas producing multispecific autoantibodies use heavy-chain- (VH) and light-chain-variable region (VK) genes from various V gene families, suggesting that they do not derive from the pool of GAT precursors. Sequencing of VH and VK genes of two antibodies show that they can use closely related VHJ558, unmutated VK1, or different VK genes than those used by anti-GT antibodies. Our data demonstrate that clones producing antibodies binding to GT and self-antigens with similar-affinity constants can be activated by foreign or anti-Id antibodies carrying the internal image of the antigen or even by a synthetic peptide corresponding to the D segment of anti-Id antibodies.

Amino Acid Sequence↗
PubMed1989

[Antitubercular agents. 45. Antimycobacterial thiohydrazide].

The present paper investigates the activity of thiohydrazides containing a structural fragment of oxalic acid against Mycobacterium tuberculosis and Mycobacterium kansasii. The drugs included heterocyclic compounds as well. All compounds under study show medium activity. The minimal inhibition concentrations against Mycobacterium kansasii are approximately 3 times higher than against Mycobacterium tuberculosis. The most effective aromatic compounds have the RM values (silica gel impregnated with silicon oil-water) in the interval of 2.2-2.6.

Antitubercular Agents↗
PubMed1989

[Cool diamond burrs in test conditions].

In almost 500 differentiated measurements of temperature and grinding performance of diamond grinding tools with and without cooling grooves--in conjunction with both a turbine and a high-speed angle piece--under practical conditions, it is demonstrated how many-sided this complex of issues is; it is further demonstrated that it is not possible to generally conclude that all so-called CD grinding tools have better cooling capabilities and/or that they are better suited to prevent excessive heat generation in comparison with grinding tools without cooling grooves. This is equally applicable to grinding performance.

Carbon↗
PubMed1989

[Facial malformations and asymmetries due to first and second branchial arch syndromes].

The first and second branchial arch syndrome is a congenital affection, among whom one can range as well hereditary as non-hereditary entities. They always cause a badly mutilating facial asymmetry. In this article, the first and second branchial arch syndrome were divided in hemifacial and bilateral dysostoses. We pointed out the hemifacial microsomia, the most occurring entity in these series. From two case reports, we attempt to give a treatment synopsis of this syndrome, which is always done by a multi-disciplinary team, including dentists, orthodontists, maxillofacial surgeons and plastic surgeons.

Adolescent↗
PubMed1989

[Bacteriological studies on the use of sonic and ultrasonic units in endodontics].

Two units for root canal preparation operated in the sonic and ultrasonic range have been tested for their antibacterial action The Cavi-Endo-Unit (DeTrey/Dentsply) rendered the root canal absolutely sterile in less than 60s, while the Endo MM 3000 Sonic Air (Micro Mega) left the root canal with evident germs after as much as 5 min.

Dental Pulp Cavity↗
PubMed1989

[Stress, anxiety and audio-analgesia in dental treatment measured with the aid of biosignals].

Fear of dental treatment is undoubtedly widespread. In the present study this fear, the "stress phenomenon", has been investigated. So-called biosignals were used to demonstrate the factual presence of these "anxiety conditions"; it has been found that they are increasing at the beginning of treatment and reach peak levels during certain much feared procedures. Moreover, it has been demonstrated that audio-analgesia may reduce anxiety and stress.

Anxiety↗
PubMed1989

[Role of intraligamentous blocks in dentistry].

In more than 2,000 documented cases intraligamentous blocks were found to be an attractive and uncomplicated alternative to dental anesthesias available to date. Given adequate practice and used with discrimination, this patient-friendly method produces a fairly good local effect which is sufficient for all of the usual dental treatments requiring no more than 20 to 40 minutes. Most of them can be done without any appreciable wait and with no more than 0.2 to 0.5 ml of the anesthetic solution so that intraligamentous blocks are an excellent solution for problem patients, e.g. those with cardiac and circulatory instability, etc.

Adolescent↗
PubMed1989

[Immunopathologic mechanisms associated with granulomas and odontogenic cysts: a general review].

The authors make a general survey of the immunopathological mechanisms involved in odontogenic cysts and granulomas. The dental pulp and the sound periapical tissues contain neither inflammatory nor immunoglobin-producing cells. Dental decay associated with bacterial aggression of the dental pulp and periapical tissues might induce a nonspecific inflammation which subsequently becomes more specific. Immunoglobulins are present in fluid aspirates from odontogenic cysts and granulomas. Several investigations have pointed out nonspecific inflammatory mediators (including the C3 complement components), T lymphocytes (helpers and suppressors), B lymphocytes, protein S-100 + cells (Langerhans cells). The presence of immunoglobulins, immunocompetent cells and C3 complement components confirms that all constituents of both humoral and cell-mediated immunological reactions might play an essential role in the pathogenesis of osteolysis.

Humans↗