[Effect of testosterone on growth hormone (GH) secretory profiles in female rats].
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Animals↗
Biomedical subjects
S Akira
Publications and source records attributed to S Akira.
A radioimmunoassay for human pro-luteinizing hormone-releasing factor [pro-LRF(14-69)OH].
A radioimmunoassay (RIA) for human pro-LRF(14-69)OH was developed with an antiserum, generated in a rabbit, to [Tyr67]pro-LRF(47-67)NH2 conjugated to BSA. This antiserum bound 28-32% of [125I]pro-LRF(14-69)OH at a final dilution of 1:2500 and the binding was inhibited by pro-LRF(14-69)OH in a dose-dependent manner. The sensitivity of the RIA was 31.2-62.5 pg and the dose that inhibited 50% of the binding to the tracer was 280-320 pg. Intra- and inter-assay coefficients of variation at 50% inhibition were 8 and 12%, respectively. Neither LRF nor pro-LRF(14-37)OH was recognized by the antiserum. The dilution curve generated with human hypothalamic extract was parallel to that of pro-LRF(14-69)OH. In addition the extract yielded a major immunoreactive peak emerging in elution volumes concordant with [125I]pro-LRF(14-69)OH on Sephadex G-50 chromatography.
Antibody Specificity↗
Effects of neonatal administration of monosodium glutamate on plasma growth hormone (GH) response to GH-releasing factor in adult male and female rats.
Female and male rats were treated with monosodium glutamate (MSG; 4 mg/g b. wt.) as neonates and the capability of the pituitary gland to secrete growth hormone (GH) in response to an intravenous injection of human GH-releasing factor (GRF) was evaluated under pentobarbital anesthesia on 109 days of life. Immunoreactive GRF content in the pituitary stalk-median eminence tissue in MSG-treated rats was less than 20% of that of control. A significant dose-dependent plasma GH response was observed after the administration of two doses of human GRF (0.25 and 1 microgram/kg b. wt., i.v.) in both control and MSG-treated rats. The responses between MSG-treated and control rats were comparable in female rats, but they were significantly reduced in male MSG-treated rats. These results show that the pituitary's responsiveness to exogenous GRF is well preserved in MSG-treated rats despite prolonged and severe depletion of endogenous GRF and there exists a sex difference in the effect of MSG on GH secretion elicited by GRF.
Animals↗
Class-switching from mu to gamma 3 or gamma 2b production at pre-B cell stage.
An Abelson virus-transformed murine pre-B cell line class-switched from mu to gamma 3 or gamma 2b at the pre-B stage during culture. A class-switch was mediated by the deletion mechanism of the intervening CH genes on the active chromosome. This study showed for the first time that class-switching at the pre-B cell stage was not always confined to gamma 2b production.
Animals↗
Production of antisera to growth hormone-releasing factor: usefulness in radioimmunoassay and passive immunization.
We have produced two antisera (R-1 & R-2) to human growth hormone-releasing factor (GRF) [1-44] NH2. Both antisera can be used for human GRF radioimmunoassay (RIA) at a final dilution of 1:50000. The antiserum R-2 was specific for the C-terminal amidated sequence of human GRF-44 and selectively recognized GRF [1-44] NH2 but not GRF [1-44] OH or GRF [1-40] OH. The antiserum R-1 also significantly bound 125I-rat GRF [1-43] OH at a final dilution of 1:5000 and enabled us to establish RIA for rat GRF. In both RIA systems, intra- and inter-assay coefficients of variation at 50% inhibition were 8 and 12%, respectively. A median effective dose was 90-120 pg in human GRF RIA and 250-300 pg in rat GRF RIA. Utilizing the RIA, we demonstrated that the hypothalamic GRF content in rats which received monosodium glutamate during the neonatal period was less than 20% of that of controls. However, the hypothalamic GRF content was not altered in rats made hypothyroid by methimazole administration, another condition known to greatly impair GH secretion. An iv administration of the antiserum R-1 significantly suppressed GH release following the injection of antisomatostatin serum. Thus, these antisera can be a useful tool in examining the physiological and/or pathophysiological roles of GRF in human and rat.
Animals↗
[Surgery for ischemic heart disease secondary to familial hyperlipidemia].
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Coronary Artery Bypass↗
Effect of B cell differentiation factor (BCDF) on biosynthesis and secretion of immunoglobulin molecules in human B cell lines.
Stimulation of human B lymphoblastoid cell lines, CESS and SKW6-CL4 with BCDF induced an increase in IgG- and IgM-secreting cells, as well as a slight increase in IgG and IgM expression on their respective surfaces. Biosynthetic labeling demonstrated that BCDF stimulation induced an increase in synthesis of secretory gamma- and mu-chains, as well as their precursors. A slight but significant increase in synthesis of membrane-bound gamma- and mu-chains and their precursors was also observed by BCDF stimulation. However, an increase in synthesis of secretory heavy chains was much higher than that in membrane-bound heavy chains in both cell lines. Pulse-chase experiments showed that increased synthesis of secretory heavy chains was not due to a decrease in degradation. BCDF stimulation induced a preferential increase in mRNA specific for secretory gamma- and mu-chains in CESS and SKW6-CL4 cells, respectively. These results suggest that BCDF induces an increase in the level of mRNA specific for secretory heavy chains, and then induces final maturation of B cells into immunoglobulin-secreting cells.
Antibody-Producing Cells↗
Immunoglobulin gene expression and DNA methylation in murine pre-B cell lines.
DNA modification accompanying immunoglobulin gene expression was examined in various Abelson murine leukemia virus (A-MuLV)-transformed cell lines, which were able to differentiate from the mu- to mu+ stage or to undergo an isotype switch during in vitro culture. The C mu genes were relatively demethylated in the A-MuLV-transformed cell lines examined irrespective of whether or not the C mu genes were expressed. Normal IgM-bearing B cells, as well as a T cell line, also showed a similar DNA methylation pattern and the C mu genes were relatively demethylated. In one of the mu+ clones, however, the expressed C mu gene was heavily methylated. The DNA methylation pattern did not change and remained hypermethylated before and after gamma 2b expression in the two cell lines which underwent class switch to gamma 2b during in vitro culture, suggesting that expression of the gamma 2b gene was not accompanied by demethylation of the C gamma 2b gene. Taken together, these results indicate that DNA demethylation within and around the CH gene may not be necessary for its expression.
Animals↗
Introduction of human gamma 1 immunoglobulin genes into fertilized mouse eggs.
A rearranged human gamma 1 immunoglobulin gene was introduced into fertilized mouse eggs. The phage Ch4A-VCE-gamma 1 was constructed by ligating an EcoRI and BglII fragment of pBR322-CESSV(CE-1) containing the VDJ region with an EcoRI and BamHI fragment of Ch4A-HIg gamma 1-10 containing the gamma 1 constant region. About 200 copies of Ch4A-VCE-gamma 1 genes were introduced into fertilized mouse eggs. Of 489 eggs injected with these genes, 319 survived and were transferred to oviducts of foster mothers. Thirtyeight mice were born and were screened for the presence of human gamma 1 immunoglobulin genes by Southern blot hybridization. Five of these 38 mice had integrated human gamma 1 immunoglobulin genes. None of the human gamma 1 copies in each mouse had undergone deletions or rearrangements as judged by the Southern blotting patterns for several restriction enzymes. Human gamma 1 gene was present in several different tissues. All the mice tested so far transmit the human gamma 1 gene to a fraction of their offspring in an autosomal dominant manner. Spleen cells from transgenic mice were analyzed for immunoglobulin production by reverse plaque assay or immunofluorescence staining of cytoplasmic immunoglobulin, but synthesis and secretion of human gamma 1 chains could not be detected. No human gamma 1 immunoglobulin mRNA was detected in the liver and spleen of a transgenic mouse. The presence of the human gamma 1 immunoglobulin gene appeared to have no effect on the expression of endogenous mouse immunoglobulin genes.
Animals↗
Functional V region formation during in vitro culture of a murine immature B precursor cell line.
B lymphocytes originate from pluripotential haematopoietic stem cells and differentiate into immunoglobulin (Ig)-producing cells. B-cell lineage differentiation is accompanied by two types of immunoglobulin gene rearrangements--rearrangement of V, D and J gene segments to create a functional V gene and rearrangement of CH genes for heavy-chain switching. These results, however, have been obtained mainly by analysis of immunoglobulin gene organization of myeloma cells. Baltimore and his colleagues have established Abelson murine leukaemia virus (A-MuLV)-transformed cell lines and found a few lines capable of carrying out kappa-gene rearrangement or undergoing isotype switching during in vitro culture. To study early B-cell lineage differentiation events, we have now also established A-MuLV-transformed cell lines which are capable of differentiating from mu- to mu+ and of undergoing continuing rearrangement of heavy-chain genes in culture. Analysis of immunoglobulin gene organization of these transformed cells revealed that mu- cells have already undergone DNA rearrangements involving JH segments but an additional rearrangement of JH segments is required for initiation of mu-chain synthesis. Southern blot analysis of the DNA and two-dimensional gel electrophoresis of intracytoplasmic mu-chain show that mu-chain diversity with respect to antigen specificity may be generated during this second rearrangement process. As no rearrangement of light-chain genes takes place in these cells, this implies that light-chain gene rearrangement requires some further change, or a different enzyme.
Abelson murine leukemia virus↗
Isotype switching in murine pre-B cell lines.
Isotype switching at the pre-B cell stage was studied by employing A-MuLV-transformed cell lines. Two gamma 2b-producing cell lines that did not have other cytoplasmic heavy chains or light chains were established from A-MuLV-transformed cell lines. One clone (SL2-1-52) arose spontaneously from a non-Ig-producing cell line (SL2-1) during in vitro culture. Another clone (AT11-2-24-6-99) underwent isotype switching from a mu-producing cell line (AT11-2-24-6), which had been derived from another non-Ig-producing line (AT11-2). Southern blot analysis of two gamma 2b-producing clones was performed in comparison to that of their respective parent clones. The results showed that isotype switching can operate at the stage of pre-B cells by a CH gene deletion mechanism without utilizing the switch region. In addition, the possibility is presented that deletion of the intervening CH genes could occur prior to the formation of the functional V region-coding DNA segment. This indicates that the prior expression of mu chains is not obligatory for the expression of other isotypes and that isotype commitment could occur in pre-B cells.
Abelson murine leukemia virus↗
Relationship between the rearrangement of immunoglobulin genes, the appearance of a B lymphocyte antigen, and immunoglobulin synthesis in murine pre-B cell lines.
Eighteen Abelson virus-transformed immature B cell lines were established and immunoglobulin biosynthesis, expression of a B lymphocyte antigen detected by a monoclonal antibody, and rearrangement of immunoglobulin genes in these cell lines were studied. Only one cell line (A1) synthesized micro-chains but no light chains, and the other cell lines synthesized no detectable immunoglobulins. None of the cell lines established had detectable membrane-associated IgM. Fifteen cell lines expressed a B lymphocyte antigen on their cell surfaces. In three cell lines, however, the majority (greater than 99%) of cells did not express this antigen. Heavy chain genes were rearranged on both chromosomes in all the cell lines, although one heavy chain gene was deleted in three cell lines. In 12 of 18 cell lines, one or both kappa-chain genes were rearranged. In six cell lines, however, both kappa-chain genes remained in embryonic form; lambda-chain genes were in embryonic form in all the cell lines. These results suggested the hierarchy of Ig gene rearrangements, beginning with mu and proceeding to kappa and then to lambda. JH rearrangement was also shown to precede the appearance of a B lymphocyte antigen. In three cell lines (A1-A3), which were considered subclones derived from a single common precursor, it was suggested that one rearranged JH gene was functional, and the other was nonfunctional, indicating that allelic exclusion already operated in pre-B cells.
Abelson murine leukemia virus↗
Signal transducer and activator of transcription protein (STAT): its relation to Th1/Th2-mediated diseases.
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Immune System Diseases↗
Functional expression of a microinjected Ed alpha gene in C57BL/6 transgenic mice.
The class II major histocompatibility antigens, I-A and I-E, have been detected on the surface of certain immunocompetent cells, including B lymphocytes and monocytes. These molecules are involved in cell-cell interactions in the immune responses. Each class II antigen consists of two subunits, alpha and beta chains, and the genes encoding these subunits have been well characterized at the molecular level. To analyse the regulatory mechanism of E alpha gene expression and the role of the I-E antigen in the regulation of the immune responses, we have produced transgenic mice by microinjecting cloned Ed alpha genes into fertilized eggs of C57BL/6 mice of b haplotype. This strain of mouse carries a deletion in the upstream (5') region of the E alpha gene covering the transcriptional promoter and, therefore, does not express this gene. Interestingly, this genetic defect of the E alpha gene is accompanied by the inability of the host mouse to respond to a certain set of antigens, phenomena generally termed Ir gene control. We report here that the Ed alpha genes are expressed in these transgenic mice to form the I-Ed alpha Eb beta antigen on the surface of B lymphocytes and monocytes and that these I-E antigens are functional in terms of the induction of a mixed lymphocyte reaction and the restoration of immune responsiveness to poly(L-glutamic acid-L-lysine-L-phenylalanine) (GL-Phe).
Animals↗