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Biomedical subjects

M Sela

Publications and source records attributed to M Sela.

At least 163 records · Page 9Linked to original sources
PubMed1983

Fine specificity of antibodies to the synthetic polypeptide poly(L-tyrosine, L-glutamic acid)-poly(DL-alanine)--poly(L-lysine) and its ordered analogs as followed by solid-phase radioimmunoassay.

The fine specificity of antibodies against (T,G)-A--L and its ordered analogs (T-T-G-G)-A--L and (T-G-T-G)-A--L was studied. Fifty percent of the antibodies against (T,G)-A--L are directed toward the T-T-G-G determinants and 19% against T-G-T-G-like determinants. The rest of the antibody response to (T,G)-A--L is directed against determinants which exist in (T,G)-A--L but are not cross-reactive with either T-T-G-G- or T-G-T-G-like determinants. Although (T-T-G-G)-A--L and (T-G-T-G)-A--L differ only in the sequence of tyrosine and glutamic acid in their side chains, no crossreactivity was observed between antibodies toward the two ordered polypeptide antigens.

Animals↗
PubMed1983

Intraoral radiation carrier for edentulous patients.

The principles of fabricating an intraoral radioactive carrier have been described to treat malignant diseases of the oral cavity. The prosthesis provides consistent direction and fixation of the radioactive source into the same location.

Brachytherapy↗
PubMed1983

Monoclonal antibodies to the synthetic adjuvant muramyl dipeptide: characterization of the specificity.

Monoclonal antibodies to MDP were prepared by hybridization of NSO myeloma cells with spleen cells of BALB/c mice immunized with MDP conjugated to methyl-BSA. Hybridomas secreting anti-MDP antibodies were selected by the binding activity of their supernates to MDP-A--L using a radioimmunoassay. After cloning in soft agar, the specificities of monoclonal anti-MDP antibodies were assayed by an inhibition of ELISA with various derivatives of MDP. Fine structural analysis of specificity for one such clone (2-4) is reported. This antibody recognizes the N-acetyl-muramic acid (N-Ac-Mur) linked to the dipeptide but not N-Ac-Mur or/and dipeptide alone. The N-Ac group on muramic acid is an important antigenic determinant and the glycopeptide linkage seems to be crucial in presenting the sugar moiety. Conservative substitution of L-Ala (i.e. by L-Ser or L-Val) had no effect on the binding ability to the antibody whereas a radical change, i.e. replacement of L-Ala by L-Pro or N-methyl-L-Ala completely abolished the antigenicity of the molecule. There was no clear correlation between biological activities of various derivatives of MDP and their ability to react with this antibody. Some possible hypotheses explaining this lack of correlation are presented.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Antibodies against synthetic peptides of the B subunit of cholera toxin: crossreaction and neutralization of the toxin.

Six peptides corresponding to various segments of the B subunit of cholera toxin have been synthesized and covalently linked to tetanus toxoid. Of the antibodies raised in rabbits against these conjugates, four crossreacted to different extents with the intact B subunit and whole native cholera toxin. Antisera to the peptide of sequence 75-85 were not crossreactive, whereas elongation by six amino acid residues resulted in a peptide (69-85) leading to antibodies crossreactive with the cholera toxin. Of most interest was peptide CTP3 (50-64), which was the only one that reacted with antisera to cholera toxin and which led to antibodies reacting with the cholera toxin to a similar level as its homologous peptide-antipeptide reaction. Indeed, antisera to CTP3 neutralized significantly the biological activity of cholera toxin, as followed by skin vascular permeability and by fluid accumulation in ligated small intestinal loops of rabbits.

Amino Acid Sequence↗
PubMed1983

Effect of a conjugate of daunomycin and purified polyclonal or monoclonal antibodies to rat alpha-fetoprotein on the growth of alpha-fetoprotein-producing tumor cells.

Monoclonal antibodies to rat alpha-fetoprotein (AFP) were produced by hybridization of mouse myeloma cells with spleen cells from mice immunized with rat AFP. The monoclonal antibodies as well as horse anti-rat AFP antibodies were coupled via a dextran bridge to daunomycin. Both types of conjugates were tested for their antitumor activity in vitro and in vivo. They were equally cytotoxic to the rat AH66 hepatoma cell line in culture. Rats challenged with hepatoma cells were treated with the conjugates by either intraperitoneal or intravenous injection. Daunomycin conjugates with horse-anti-AFP and monoclonal mouse anti-AFP were capable of delaying the tumor development more efficiently than were the controls of antibodies or free drug, mixtures of drug with antibodies, and a conjugate of drug and normal Ig. The specific conjugates were considerably more effective when the treatments were given intravenously. The specific conjugates produced 60% long-term survival, whereas the controls only slightly delayed tumor development.

Animals↗
PubMed1983

Silicone ectoprostheses for correction of facial defects.

Twenty-two patients with congenital and acquired defects, rehabilitated with silicone ectoprostheses, were followed up for 6 mo to 4 yr. The simplicity of the procedure, its good results and the early physical and social rehabilitation attained, favor its use when adequately indicated.

Adolescent↗
PubMed1982

Multiple sclerosis: trial of a synthetic polypeptide.

A synthetic polypeptide, copolymer I (COP I), composed of alanine, glutamic acid, lysine, and tyrosine, has been demonstrated to be nonencephalitogenic and nontoxic in laboratory animals, yet it is capable of suppressing experimental allergic encephalomyelitis. A preliminary open trial examined the ability of COP I to alter the course of disease in 12 patients with chronic progressive and 4 with exacerbating-remitting multiple sclerosis (MS). After therapy for as long as two years or more, no undesirable side reaction was noted in any patient. Three patients with chronic progressive MS and 2 with exacerbating-remitting disease are better. These results, which may represent simply a placebo effect or may be a significant response, are now being examined in randomized, placebo-controlled, double-blind pilot trials.

Adult↗
PubMed1982

Evaluating cosmetic results in maxillofacial prosthetics.

Fifty-two patients with maxillofacial prosthetic restorations answered questionnaires to measure their feelings of well being. Their overall scores averaged 38.6%. Subsequently, three independent observers reported their evaluation for each patient, yielding a combined improvement score of 35.1%. The apparently low figures reflect the strict criteria used. Men patients showed a greater response than women patients both in subjective questionnaire scores and objective evaluation rating. Greater improvement was reported in younger patients, yet the objective evaluators found better success in the older age group. The original etiology of the maxillofacial defect, i.e., traumatic injury, congenital malformation, or surgical tumor excision was the most important factor in the evaluation. Questionnaire scores were similar in all categories. However, the objective evaluation, especially that of the sculptor, who judged color slides alone, was significantly higher in the injury group than in cancer patients. Apparently, the inner desperation of many cancer patients is apparent in their facial appearance even after complete prosthetic rehabilitation. Such patients deserve greater psychologic attention during their treatment. Prosthodontists should realize their tendency to be hypercritical of their own treatment results. Their constant striving for improvement in their treatment results leads them to belittle their achievements and to underestimate their success. Public opinion, as represented by the artists, is significantly more enthusiastic about maxillofacial prosthetic achievements.

Adolescent↗
PubMed1982

Successful immunization with a totally synthetic diphtheria vaccine.

Three peptides corresponding to fragments of diphtheria toxin have been synthesized. They include the previously described tetradecapeptide and two structural analogs, the hexadecapeptide and the octadecapeptide. Conjugates of these peptides to proteins or a synthetic carrier have induced in guinea pig protection against the dermonecrotic activity of diphtheria toxin. All of the conjugates were immunogenic when administered either in complete Freund's adjuvant or with N-acetylmuramyl-L-alanyl-D-isoglutamine in aqueous medium. Positive immune response toward the octadecapeptide was obtained in mice as well. In this case, the immunogenic combinations were conjugates with bovine serum albumin administered either in Freund's adjuvant or with the muramyl dipeptide and a complete synthetic conjugate comprising both the octadecapeptide and the muramyl dipeptide covalently attached to a synthetic carrier, multichain poly(DLAla). This last immunogen, which induced the most effective immune response, is a completely synthetic immunogen with built-in adjuvanticity and induces protective antitoxic immunity when administered in a physiological medium.

Adjuvants, Immunologic↗
PubMed1982

Cellular analysis of specificity of antibodies and of delayed type hypersensitivity responses toward some structurally related synthetic antigens: boosting is determined by specificity of T cells.

The crossreactivity between the random synthetic polypeptide antigen poly(Tyr,Glu)-poly(DLAla)--poly(Lys) [(T,G)-A--L] and its ordered-sequence analogs (Tyr-Tyr-Glu-Glu)-poly(DLAla)--poly(Lys) [(T-T-G-G)-A--L] and (Tyr-Glu-Tyr-Glu)-poly(DLAla)--poly(Lys) [(T-G-T-G)-A--L] at the level of humoral and cellular responses was studied. For delayed type hypersensitivity responses, (T,G)-A--L-activated T cells could be challenged with the homologous antigen as well as with the ordered analogs. T cells activated by (T-T-G-G)-A--L could be challenged with either the homologous antigen or with (T,G)-A--L but not with (T-G-T-G)-A--L. Similarly, no cross stimulation was observed between (T-G-T-G)-A--L-activated cells and (T-T-G-G)-A--L, whereas (T,G)-A--L could challenge the latter cells to mediate significant responses. Similar but not identical cross reactions were observed when primed spleen cells or lymph nodes were transferred to irradiated recipients that were boosted for the production of antibodies. In contrast to observations at the level of cellular responses, (T-G-T-G)-A--L-primed spleen or lymph node cells could not be boosted with (T,G)-A--L for the production of detectable amounts of antibodies, although boosting with the homologous antigen resulted in significant levels of (T-G-T-G)-A--L-specific antibodies. Transfer experiments in which mixtures of T and B cells, each primed to a different ordered polypeptide antigen, were injected into irradiated recipients showed that successful cooperation occurs provided that the boost is given with the T-cell-specific antigen. The antibodies produced were specific to the antigen used for B-cell priming. The T-cell-B-cell collaboration probably occurs through specific determinants that are shared between the two antigens in which the ordered peptides are attached to the same multichain polymer and that are recognized by both the T and the B cells.

Amino Acid Sequence↗
PubMed1982

Effect of a conjugate of daunomycin and antibodies to rat alpha-fetoprotein on the growth of alpha-fetoprotein-producing tumor cells.

Daunomycin was covalently attached via a dextran bridge to specific antibodies against rat alpha-fetoprotein produced in a horse. The effect of this conjugate on an alpha-fetoprotein-producing tumor was investigated in terms of cytotoxicity and inhibition or retardation of tumor development. Under the experimental conditions used, the covalent conjugate was by both criteria more efficient than either daunomycin alone or a mixture of daunomycin and specific antibodies or a conjugate of daunomycin with horse immunoglobulin. These results show that the conjugate may be useful as a specific cytotoxic agent against alpha-fetoprotein-producing tumors.

Animals↗
PubMed1982

Chemotherapy by intravenous administration of conjugates of daunomycin with monoclonal and conventional anti-rat alpha-fetoprotein antibodies.

Monoclonal antibodies to rat alpha-fetoprotein (AFP) were produced by hybridization of mouse myeloma cells with spleen cells from mice immunized with rat AFP. The monoclonal antibodies as well as horse anti-rat AFP were coupled via a dextran bridge to daunomycin. Both types of conjugates were tested in vitro and in vivo for their anti-tumor activity. They were equally cytotoxic to rat AH66 hepatoma cell line in culture. Rats challenged with hepatoma cells were treated with the conjugates either by intraperitoneal or intravenous injections. Daunomycin conjugates with horse anti-AFP and monoclonal mouse anti-AFP were capable of delaying the tumor development more efficiently than the controls of antibodies or free drug, mixtures of drug with antibodies, and a conjugate of drug and normal immunoglobulin. The specific conjugates were considerably more effective when the treatments were given intravenously. The specific conjugates produced 60% long-term survival, whereas the controls delayed only slightly tumor development.

Animals↗