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E Simpson

Publications and source records attributed to E Simpson.

At least 109 records · Page 6Linked to original sources
PubMed1992

Deletion mapping of H-Y antigen to the long arm of the human Y chromosome.

A gene encoding or controlling the expression of the H-Y transplantation antigen was previously mapped to the human Y chromosome. We now report the sublocalization of this gene on the long arm of the human Y chromosome. Eight patients with Y-chromosomal abnormalities were examined with a series of existing and new DNA markers for the Y chromosome. The resulting deletion map was correlated with H-Y antigen expression. We conclude that the H-Y antigen gene maps to a portion of deletion interval 6 that is identified by specific DNA markers.

Adolescent↗
PubMed1992

Recombination between the X and Y chromosomes and the Sxr region of the mouse.

The Sxr (sex-reversed) region that carries a copy of the mouse Y chromosomal testis-determining gene can be attached to the distal end of either the Y or the X chromosome. During male meiosis, Sxr recombined freely between the X and Y chromosomes, with an estimated recombination frequency not significantly different from 50% in either direction. During female meiosis, Sxr recombined freely between the X chromosome to which it was attached and an X-autosome translocation. A male mouse carrying the original Sxra region on its Y chromosome, and the shorter Sxrb variant on the X, also showed 50% recombination between the sex chromosomes. Evidence of unequal crossing-over between the two Sxr regions was obtained: using five markers deleted from Sxrb, 3 variant Sxr regions were detected in 159 progeny (1.9%). Four other variants (one from the original cross and three from later generations) were presumed to have been derived from illegitimate pairing and crossing-over between Sxrb and the homologous region on the short arm of the Y chromosome. The generation of new variants throws light on the arrangement of gene loci and other markers within the short arm of the mouse Y chromosome.

Animals↗
PubMed1992

A molecular deletion map of the Y chromosome long arm defining X and autosomal homologous regions and the localisation of the HYA locus to the proximal region of the Yq euchromatin.

41 Y-linked DNA probes that detect sequences on the Y chromosome long arm have been used to analyse genomic DNA from a series of 23 patients with deletions of Yq. Southern blot analysis has differentiated 15 distinct breakpoints, which divide Yq into 14 mapping intervals. From the pattern of DNA sequences present in each patient, it has been possible to produce a congruent deletion map, with the exception of two cases which are not compatible with the consensus order. These patients can be explained by the presence of inversion polymorphisms on Yq in the general population or by complex rearrangements induced during the formation of the deleted chromosomes. The distribution of sequences on the Y long arm has defined distinct regions of homology with autosomes, the Y short arm and the long and short arms of the X. A number of the patients have been typed for the presence or absence of H-Y antigen (as determined by the cytotoxic T-cell assay) and it has been possible, from analysis of informative cases, to assign the locus to the proximal region of the Yq euchromatin.

Cell Line↗
PubMed1992

Determination of aromatase cytochrome P450 messenger ribonucleic acid in human breast tissue by competitive polymerase chain reaction amplification.

Local production of estrogen in breast tissue may influence the growth of breast cancers. Peripheral conversion of C19 steroids to estrogens is catalyzed by the aromatase enzyme complex which is comprised of a specific form of cytochrome P450, aromatase cytochrome P450 (P450AROM) and the flavoprotein, NADPH-cytochrome P450 reductase. To evaluate P450AROM mRNA levels in breast tissue, a specific competitive polymerase chain reaction amplification procedure was devised. In this method, a rat P450AROM complementary RNA is coamplified as an internal standard in order to compare amplification reactions. The amplification products are recognized by hybridization with 32P-labeled oligonucleotides specific for each species. Densitometry is used to quantitate autoradiographs. Initial studies using RNA from whole breast tissue obtained from reduction mammoplasty revealed linearity of the relationship between the densitometer signal from the human amplification product and total RNA concentration. Breast tissue was then separated into a floating adipocyte fraction and a pelleted fraction containing the other cellular elements by collagenase digestion and centrifugation. Comparison of specific content of aromatase amplification product per unit weight of RNA extracted from adipocytes and pelleted cells revealed considerably higher levels in the RNA from the nonadipocyte fraction. Immunocytochemical characterization of this fraction revealed the presence of several cell types including macrophages, ductal epithelial cells, and endothelial cells, but primary cells of stromal origin.

Animals↗
PubMed1992

Effect of radiation dose on the development of mixed haemopoietic chimerism following T cell-depleted allogeneic bone marrow transplantation.

The presence of mixed haemopoietic chimerism (MXC) was evaluated by cytogenetic and molecular analysis in 48 patients undergoing T cell-depleted BMT. The dose of total body irradiation (TBI) prescribed to all patients (14.4 Gy) was calculated to compensate for the absence of T cells in the graft. The actual midline dose of TBI received, however, differed significantly depending on the method of TBI administration. Thus, 35 adult patients received an average midline dose of 14.3 Gy, while 13 children received a lower dose of 13 Gy. The incidence of MXC in the adult group, who had received very close to 14.4 Gy to the midline, was 34% (12/35), which is lower than in most reported T cell-depleted series. During follow-up, chimerism remained relatively stable with time but varied between haemopoietic lineages. There was no relationship with relapse. MXC in the 13 children who had received a lower midline TBI dose was significantly higher at 69% (9/13) (p < 0.05) and increased to 90% (9/10) if patients who received additional chemotherapy in their conditioning were excluded (p = 0.001). This suggests that, in terms of marrow ablation, relatively small changes in the dose of TBI may be biologically significant, at least at this dose range. Again, in the lower TBI group MXC was not predictive of relapse.

Adolescent↗
PubMed1991

Genes encoding ligands for deletion of V beta 11 T cells cosegregate with mammary tumour virus genomes.

The T-cell receptor (TCR) repertoire is selected in the thymus after rearrangement of genes encoding TCR alpha and beta chains. Selection is based on the recognition by newly emergent T cells of self-ligands associated with molecules of the major histocompatibility complex: some combinations result in positive selection, others in negative selection. Negative selection, or clonal deletion, is an important mechanism for eliminating autoreactive T cells. A group of self-ligands involved in clonal deletion was identified because they, like exogenous superantigens, were recognized by almost all T cells expressing particular TCR V beta genes. V beta 17a T cells are deleted by a tissue-specific ligand; V beta 6, V beta 7, V beta 8.1 and V beta 9 T cells are deleted by the minor lymphocyte-stimulating (Mls) determinant Mls-1a; V beta 3 T cells by Mls-2a and Mls-3a; V beta 11 T cells by ligands encoded by independently segregating genes; and V beta 5 T cells by ligands encoded by two genes. Chromosome mapping using recombinant inbred strains of mice and classic backcrosses show that Mls-1a in DBA/2 mice is encoded on chromosome 1, that one of the two ligand genes for deletion of V beta 5 T cells maps to chromosome 12 and that a ligand gene for V beta 11 deletion is linked to the CD8 locus on chromosome 6. Here we present evidence from three sets of backcross mice for concordance between V beta 11 deletion ligand genes on chromosomes 6, 12 and 14 and endogenous mouse mammary tumour virus integrant (Mtv) genomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Characterization of pancreatic islet cell infiltrates in NOD mice: effect of cell transfer and transgene expression.

Insulin-dependent diabetes mellitus can be transferred into young irradiated non-obese diabetic (NOD) mice by spleen cells from a diabetic NOD donor. T cells (both L3T4+ and Ly-2+) enter the pancreas 2 weeks following transfer. They are present initially at peri-islet locations but progressively infiltrate the islet with accompanying beta cell destruction. The infiltrate is heterogeneous with respect to V beta usage. Inflammatory macrophages (Mac-1+, F4/80+) can be detected at peri-islet locations at 1 week after transfer and continue to be recruited during the disease process. Their presence at the initiation of disease suggests that their primary function may be autoantigen presentation. Increased expression of major histocompatibility complex (MHC) class I molecules is observed on both endocrine and exocrine tissue in areas of intra-islet infiltration. MHC class II and ICAM-1 expression was restricted to the cells constituting the inflammatory infiltrate. Expression of these molecules was not observed on beta cells implying that presentation of autoantigen by the beta cell itself does not play a role in the beta cell destruction in NOD mice.

Animals↗
PubMed1991

Variable spread of X inactivation affecting the expression of different epitopes of the Hya gene product in mouse B-cell clones.

Cloned B-cell lines from a female T16H/XSxr mouse in which Tdy expression was suppressed due to X inactivation and from a male X/XSxr mouse, both of the (kxb)F1 haplotype, were examined for H-Y expression. This was determined both by their ability to act as targets for H-2k and H-2b-restricted H-Y-specific cytotoxic T cells and by their ability to stimulate the proliferation of H-2Kk, H-2Db (class I) and Ab (class II)-restricted T-cell clones. In B-cell clones from the T16H/XSxr mouse, expression of H-Y/Db exhibited partial X inactivation and only a proportion (congruent to 30%) of the cells were targets for or stimulated H-2Db-restricted H-Y-specific T cells. In contrast, H-Y epitopes restricted by H-2k (H-Y/Kk, H-Y/Dk) and Ab (H-Y/Ab) exhibited no X inactivation. Furthermore, no inactivation of H-Y/Db, H-Y/Ab, or H-Yk was observed in the male X/XSxr mouse. These results indicate that the T16H/XSxr female is a mosaic, as a result of the variable spread of X inactivation into the Sxr region. They further suggest that the H-Y antigen recognized in association with H-2k and H-2Db class I molecules and Ab class II molecules may be the product of more than one gene.

Animals↗
PubMed1991

Cyclosporine monitoring by fluorescence polarization immunoassay.

The monitoring of cyclosporine levels in whole blood and serum has become a routine procedure for the post-transplant management of immunosuppression. We have developed fluorescence polarization immunoassays for cyclosporine in whole blood and in serum using a monoclonal antibody. These assays are fast (20 determinations in less than 22 min), sensitive (25 micrograms/L for whole blood samples and 10 micrograms/L for serum samples), and precise (CV less than 7% in both assays). Cross-reactivities with AM1 (Metabolite 17) and AM4N (Metabolite 21) are less than 8.5 and 2.5%, respectively, for both assays.

Antibodies, Monoclonal↗
PubMed1991

Minor histocompatibility antigens.

Immune responses against foreign tissue or organs can be directed against alloantigenic differences between donor and host encoded by genes of the major histocompatibility complex (MHC; HLA in man and H-2 in mouse). However, when MHC antigens are matched, as in HLA-identical siblings, or between different mouse strains sharing the same H-2 haplotype, graft rejection still occurs and is then directed against alloantigenic differences termed minor histocompatibility (H) antigens. Their molecular nature is not yet determined but they are recognised by T cells in an MHC-restricted manner, so are assumed to be derived from molecules co-expressed with MHC class I or II glycoproteins, possibly as peptides or as "super-antigens". The genes encoding them are scattered throughout the genome, including the Y chromosome, on which the H-Y antigen gene has been mapped in both man and mouse. One striking feature of minor H antigens is their recognition by T cells but not by antibodies. This made work with them, before our ability to generate T cell responses and maintain T cell clones in vitro, very slow but currently the use of MHC-restricted T cell clones has enabled detailed mapping studies and should eventually allow for their molecular characterisation.

Animals↗
PubMed1991

Regulation of expression of the genes encoding steroidogenic enzymes.

In recent years it has become apparent that tropic hormones involved in steroidogenesis act to regulate the expression of the enzymes involved in the various steroidogenic pathways. This is particularly evident in the ovary where the episodic secretion of steroids throughout the ovarian cycle is regulated largely by changes in the levels of the particular enzymes involved in each step of the steroid biosynthetic pathways. Recently, the genes for the various cytochrome P450 species involved in ovarian steroidogenesis, namely cholesterol side-chain cleavage P450 (P450SCC), 17 alpha-hydroxylase P450 (P450(17 alpha], and aromatase cytochrome P450 (P450AROM) have been isolated and characterized, making it possible to study the regulation of expression at the molecular level. To this end, a series of chimeric constructs have been prepared in which fragments of the 5'-untranslated region of bovine P450(17 alpha) and P450SCC have been inserted upstream of the chloramphenicol acetyl transferase (CAT) and beta-globin reporter genes. These constructs have been used to transfect primary cultures of bovine luteal and thecal cells. The results indicate that cAMP responsiveness lies within defined regions of genes which do not contain a classical CRE, similar to previous results utilizing adrenal cells in culture. Furthermore, although constructs containing both the P450(17 alpha) and P450SCC 5'-upstream regions are expressed in both luteal and thecal cell cultures, only those containing the P450SCC sequences are expressed in luteal cells. Studies on the expression of P450AROM indicate that the promoter which is responsible for its expression in human placenta is not operative in the corpus luteum. Thus estrogen biosynthesis may be regulated by the differential use of tissue specific promoters, thus accounting for the complexity and multifactorial nature of the expression of this activity.

Animals↗
PubMed1991

Phenotypic and functional studies of human peripheral blood lymphocytes engrafted in scid mice.

CB.17 mice homozygous for the scid defect have been used as recipients of peripheral blood lymphocytes (PBL) from normal humans and from patients suffering from common variable immunodeficiency (CVI) types A and B. Following intra-peritoneal injection of PBL, such mice become chimeric with human cells, as evidenced by the presence in their serum of human immunoglobulins, which persist for a number of months. Under these conditions, B cells from CVI patients are also triggered to produce immunoglobulin. In contrast, T cells in the inocula, although they persist for 1 or 2 months in the peritoneal cavity, do not appear to function normally in antigen-specific responses and they do not recirculate in the recipient mice.

Animals↗
PubMed1990

Transfer of diabetes in mice prevented by blockade of adhesion-promoting receptor on macrophages.

Insulin-dependent diabetes mellitus (IDDM) is a disease with an autoimmune aetiology. The non-obese diabetic mouse is a good spontaneous animal model of the human disease, with IDDM developing in 50-80% of female mice by the age of 6 months. The disease can be transferred by splenic T cells from diabetic donors and is prevented by T-cell depletion. The mechanism(s) by which the beta cell is specifically destroyed is not known, but T cells and macrophages have both been implicated, based on the presence of macrophages in the infiltrated islet and the ability of chronic silica treatment to prevent disease. The monoclonal antibody 5C6 is specific for the myelomonocytic adhesion-promoting type-3 complement receptor (CR3 or CD11b/CD18) and does not bind to T cells. Here we show that blockade of macrophage CR3 in vivo prevents intra-islet infiltration by both macrophages and T cells and inhibits development of IDDM. We conclude that both T cells and macrophages have an essential role in the onset of IDDM.

Animals↗