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H Bazin

Publications and source records attributed to H Bazin.

377 records · Page 21Linked to original sources
PubMedDate not supplied

Nippostrongylus brasiliensis infection can induce IgE production in rnu/rnu rats.

Although rnu/rnu homozygous athymic rats are generally considered to be entirely deficient in mature T cells and unable to produce any T-cell-dependent immune response, we were able to induce slight IgE production in some Nude rats after Nippostrongylus brasiliensis infection. This report stresses the importance of taking the greatest care in the use of congenitally athymic rnu/rnu rats, as strong stimulation can, in some individuals, induce reactions which are generally considered to be T-cell-dependent. Hypotheses explaining this phenomenon are suggested.

Animals↗
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Subclass restriction of the antiidiotypic antibody response in the rat.

Antiidiotypic antibodies were induced in LOU/M rats by immunization with two myeloma proteins of LOU origin: IR-162 (IgE) and IR-418 (IgG2a). Antibodies to IR-162 were easily obtained after a limited number of immunizations with protein in soluble form; polymerization with glutaraldehyde did not enhance immunogenicity. Antibodies to IR-418 appeared only after a large number of immunizations with protein in polymerized form or with protein copolymerized with rabbit IgG. All of the antibodies, either to IR-162 or to IR-418, were found to be idiotype-specific. In every case for which significant levels of antiidiotypic antibodies were produced, most or all of the antibodies belonged to rat IgG1 subclass. Since, in mice, antiidiotypic antibodies are restricted to the IgG1 subclass, our results indicate a functional analogy between rat and mouse IgG1. Our studies also suggest that the rat IgG1 subclass may be predominantly expressed in T-cell-dependent antibody responses, such as production of antiidiotypic antibodies.

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Lymphocyte disappearance and reappearance after a single whole-body irradiation dose of 5 Gy.

The effects of a single exposure to 5 Grays of caesium gamma rays administered at a high-dose rate were investigated in rat lymphocyte populations. Such a dose completely depleted the B-cell population but never totally depleted the T-cell population. T and B lymphocytes reappeared in the spleen after 10-15 days and somewhat later in the mesenteric lymph nodes and Peyer's patches. In the spleen, non-circulating B lymphocytes of the marginal zone reappeared after a few days, as did the B lymphocytes of the follicles. Lymphoid tissues were observed to have recovered their normal aspect between days 50 and 60 after irradiation; however, even at that time, the germinal centres had not yet returned to normal.

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End attachment of phenol-oligonucleotide conjugates to diazotized cellulose.

The synthesis of a novel phosphoramidite reagent with a hexanediol backbone is described. This reagent has been used to incorporate a phenol moiety on an oligonucleotide (ODN) directly in the course of its automated synthesis. Multiple phenol attachments can be achieved by repetitive coupling cycles. A simple and rapid immobilization method is described where phenol-modified ODNs are covalently attached to diazotized cellulose. The binding capacity of the membrane can be modulated, depending on the ODN concentration used, to ca. 180 pmol/cm2. There is at least 80% end attachment of the ODN through the phenol group. In addition, the phenol residue can be used as a carrier for the radiolabeling with 125I. The non-nucleosidic hexanediol derivative incorporated at the 5'-end of the ODN is recognized as a substrate by the T4 polynucleotide kinase and the terminal hydroxyl group is successfully phosphorylated allowing its 32P labeling.

Base Sequence↗
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Rat c-myc oncogene is located on chromosome 7 and rearranges in immunocytomas with t(6:7) chromosomal translocation.

Two B-cell-derived tumours, human Burkitt's lymphoma (BL) and murine plasmacytoma (MPC), are regularly associated with a distinctive form of chromosomal translocation (for reviews see refs 1, 2). In BL, the distal portion of chromosome 8 breaks off and is transposed, in most cases, to chromosome 14, known to carry the immunoglobulin heavy-chain locus. In about 5% of the cases the same distal part of the chromosome 8 has moved to either chromosome 2 or 22, to the neighbourhood of the kappa or the lambda locus, respectively. In MPC the distal region of chromosome 15 is transposed to the chromosome 12, known to carry the immunoglobulin heavy-chain locus, or enters into reciprocal exchange with the kappa locus-carrying chromosome 6 (ref. 7). Several laboratories have located c-myc, the cellular homologue of the MC29 retroviral oncogene v-myc, to human chromosome 8 (refs 8-10) and mouse chromosome 15 (refs 11-13). It has also been shown that the BL- and MPC-associated translocations remove the c-myc gene from its original site and transpose it into or close to one of the immunoglobulin gene clusters. In view of the above findings we also looked for possible involvement of the c-myc gene in a B-cell-derived tumour of a third species, the rat. Rat immunocytomas of spontaneous origin carry a reciprocal translocation between chromosomes 6 and 7 (ref. 17). Here we have localized the c-myc locus to chromosome 7 of the rat. Moreover, we have found that the c-myc gene was rearranged in four of five immunocytomas carrying the characteristic chromosomal translocation.

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The specific IgM response in rats genetically selected for high or low serum IgM level.

The IgM response to SRBC in a line of rats selected for high serum IgM was higher and lasted longer than that in a line of rats selected for low IgM, while the response to TNP-LPS was similar at its peak in the two lines but persisted longer in the 'high' line. The difference between the lines is therefore more likely to be at the macrophage and/or the T cell level than at the B cell level.

Animals↗
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The influence of different adjuvants on the production of IgD and IgE antibodies.

The aim of this study was to investigate the relationship between the synthesis of IgD and IgE antibodies upon the administration of antigen. Different adjuvants were used in order to find the optimal way of inducing in rats the synthesis of IgD and IgE antibodies. Ovalbumin was used as antigen. Fair amounts of IgE antibodies were produced using Al(OH)3 or Bordetella pertussis and Al(OH)3 as adjuvant. Only small quantities of IgE antibodies were formed when either Freund's complete adjuvant (FCA) or no adjuvant were used. IgD antibodies are formed upon the immunization with ovalbumin and FCA or B. pertussis in combination with Al(OH)3. Using Al(OH)3 alone as adjuvant or antigen alone resulted in only very minute quantities of specific IgD. Total serum IgE levels raised in the rats immunized with Al(OH)3 or B. pertussis and Al(OH)3. Total serum IgD was increased after immunization with ovalbumin and B. pertussis in combination with Al(OH)3.

Adjuvants, Immunologic↗
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Chronosynergistic effects of lighting schedule-shift and cefodizime on plasmacytoma growth and host survival time.

Lighting regimen shifts can modify the effects of cefodizime, for the purpose of a chronoimmunomodulation. Two experiments were carried out on male and female LOU rats inoculated subcutaneously with plasmacytoma cells. Some rats were kept on their original LD12:12 regimen, whereas others, after tumor implantation, were subjected every second day to 6-h shifts, instituted, in alternation, as advance or delay. Daily treatment with cefodizime or placebo started when, overall, about 50% of the animals had developed a palpable tumor. A subgroup of animals contributed daily smears for the determination of the estrus cycle and further provided core temperature and activity data by telemetry. In Experiment I, the repeated shifting of the LD regimen was associated with survival time prolongation (p less than 0.05), irrespective of drug administration. Moreover, in those (female) rats repeatedly exposed to shifts of the lighting schedule, cefodizime was found to prolong survival time (p less than 0.05). The effects of cefodizime vs placebo on survival time were found to be circadian stage-dependent. In Experiment II, differing from Experiment I in the initial conditions before the institution of the shifts, cefodizime treatment was associated with a prolongation of survival time of the female rats kept on a fixed LD12:12 regimen. Both male and female rats again showed a circadian stage-dependence of the cefodizime effect. These results suggest that interactions between synchronizers of rhythms (such as shifts of the lighting regimen, the latter simulating the daily routine) and immunomodulating agents such as cefodizime may be optimized to improve treatment strategies against cancer and other diseases.

Animals↗
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Genetic control of the resistance to spontaneous immunocytoma (plasmacytoma-IR tumour) development in LOU/C rats.

Immunocytomas (immunoglobulin secreting tumours) appear with a highly spontaneous incidence in animals of the inbred LOU/C strain but never in those of the inbred OKA strain. Congenic rats with LOU/C genetic background, having either the heavy or the kappa light immunoglobulin chain loci from the OKA strain, have an immunocytoma incidence similar to that of the LOU/C strain. The congenic strain, having the major histocompatibility complex of the OKA strain on the LOU/C background, showed no immunocytoma incidence. These results indicate that the MHC locus of the rat, or a gene closely linked to it, determines resistance to immunocytoma development. Specific chromosomal translocation associated with Ig gene chromosome and c-myc play a major role in the origin of the rat IR tumours. These experiments show that the resistance of the OKA strain to the appearance of IR tumours is not correlated with special properties of Ig heavy and kappa gene segments.

Animals↗
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[Reaginic immunological responses in rats and mice].

Reaginic immunological responses present characteristics of induction which differentiate them from classical antibodies responses from other classes: among them we studied, on the one hand, the genetic control. In the case of OVO-DNP reaginic antibodies in the rat, the controls exercised by the Ag-B haplotypes or the synthesis loci of the immunoglobulin heavy chains does not seem to be sufficient to explain the experimental results. Another control exist probably. It could be linked to the global IgE serum level control; on the other hand, the IgE plasma cells. In rats infested with Nippostrongylus brasiliensis, they make their appearance in large number in the mesenteric lymph node but not in the lamina propria of the intestinal mucosa.

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Partial structure of a rat IgD molecule with a deletion in the heavy chain.

The isolation, purification and characterization of the rat IR-731 monoclonal immunoglobulin is reported. The molecule is IgD-like, as appreciated from immunochemical and biochemical characteristics. H and L chains, Fab and Fc tryptic fragments have been isolated, analyzed, and partial sequence data have been obtained, including most cysteyl-containing peptides. The heavy chain contains a deletion which encompasses most of the CH2 domain and the beginning of the CH2 domain, and observation which does not reflect the intron-exon organization depicted for some murine heavy chains at the gene level. Basic structural features of the hinge region of the IgD molecule (extreme susceptibility to proteolytic enzymes, presence of basic amino acids near its COOH-terminus) have been found for the IR-731 molecule. In addition, partial sequence of the light chains points to the existence of K subgroups in the rat. Very limited amino acid changes have been identified in the K constant region, suggesting a possible--but limited--polymorphism which might be isotypic and/or allotypic in nature.

Amino Acid Sequence↗
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Immunoglobulin production in nude rats with special attention to the IgE isotype.

The production of immunoglobulins has been studied in Nude (rnu/rnu) rats as well as in their controls (RNU/+). A prototype of humoral T-dependent immune response, the anti-DNP-OVO reaginic production was found very low in Nude rats by comparison to their controls. The percentage of Ig-bearing cells in mesenteric lymph nodes was increased to about the double of those of the control. This percentage can be explained by the absence or at least the great depletion of the thymus derived lymphocytes. On the contrary, the Ig serum levels were rather normal and could correspond to T-independent antigenic stimulation and to membrane immunoglobulin shedding, at least for the IgE isotype.

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Circadian rhythms in polyamine excretion by rats bearing an immunocytoma.

Large-amplitude circadian rhythms were observed in the urinary excretion of polyamines by rats bearing an immunocytoma. Control animals excreted polyamines at a lower rate but also with marked circadian variation. In confirmation of earlier observations, light-chain excretion by the tumor-bearing rats also exhibited a circadian rhythm, superimposed on an increasing trend. The potential of these rhythms as markers for the chronotherapy of cancer is noted.

Animals↗
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In vitro measurement of specific rat IgE antibodies.

A radioimmunoassay has been developed for measuring specific rat IgE antibodies. The method used in base on the principle of the paper radio allergo sorbent technique (PRAST) as described by Wide et al. [11]. There is a good correlation between PRAST results and passive cutaneous anaphylaxis (PCA) titer. Inhibition tests with different purified monoclonal immunoglobulins show the specificity of this in vitro technique for measuring IgE antibodies. PRAST is in general somewhat more sensitive than the PCA test.

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