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S Joyce

Publications and source records attributed to S Joyce.

51 records · Page 3Linked to original sources
PubMed1993

A multicentre comparative study of serum lipids and apolipoproteins in long-term users of DMPA and a control group of IUD users. World Health Organization. Task Force on Long-Acting Systemic Agents for Fertility Regulation Special Programme of Research, Development and Research Training in Human Reproduction.

A clinical trial was conducted in three centres to assess the effects of long-term use of the injectable contraceptive depot-medroxyprogesterone acetate (DMPA) on lipid metabolism. Fifty women who had used DMPA at a dose of 150 mg every three months for 3 to 9 years were recruited in Bangkok, Christchurch and Mexico City. They were compared to a control group of 120 IUD users. Total cholesterol, LDL-cholesterol, HDL-cholesterol, total triglycerides, apolipoproteins AI, AII and B were measured throughout one injection interval. Significant findings differed between centres. Compared to their own centre controls, DMPA users in Bangkok had higher LDL-cholesterol levels; those in Christchurch had lower HDL-cholesterol, apolipoprotein (apo) AI and apo AI/B ratio and higher apo B levels; those in Mexico City had a lower apo AI/B ratio. Further changes were observed during the injection interval, some of which were correlated to changes in serum MPA levels. It is concluded that long-term use of DMPA induces moderate changes in lipid metabolism which are unfavourable in terms of risk for atherosclerosis. This should be borne in mind when weighing the overall risks and benefits of this contraceptive method for a potential user.

Adult↗
PubMed1992

Mapping the orientation of an antigenic peptide bound in the antigen binding groove of H-2Kb using a monoclonal antibody.

The major histocompatibility complex class I molecules are receptors for intracellular peptides, both of self and non-self origin. When non-self peptides (eg., pathogen derived) are bound to the class I molecules, they form ligands for T cell receptors resulting in antigen specific lysis of the infected cells by cytotoxic T lymphocytes. Therefore, an understanding of the process of antigen recognition requires the precise definition of the structural features of the bimolecular complex formed by a single well defined antigenic peptide bound to the class I molecule. A strategy using antibodies was developed to probe the structural features of the H-2Kb containing a defined peptide in the antigen cleft. We report that the binding surface area of a Kb specific monoclonal antibody (28-13-3s) includes residues in the alpha 1 (Gly56 and Glu58) and alpha 2 (Trp167) helices of Kb thus, binding across the antigen binding groove. When cells treated with the antigenic peptide of vesicular stomatitis virus, N52-59, and its alanine substituted analogs were tested for 28-13-3s binding, it was found that position 1 of the peptide also forms a part of the antibody binding site. This finding strongly supports the positioning of the N-terminus of N52-59 proximal to pocket A, thus, assuming an orientation parallel to the alpha 1 helix.

Abelson murine leukemia virus↗
PubMed1992

Vesicular stomatitis virus antigenic octapeptide N52-59 is anchored into the groove of the H-2Kb molecule by the side chains of three amino acids and the main-chain atoms of the amino terminus.

This study describes an analysis of the interaction of individual amino acid residues of the vesicular stomatitis virus (VSV) nucleocapsid antigenic octapeptide (N52-59; Arg-Gly-Tyr-Val-Tyr-Gln-Gly-Leu) with the H-2Kb molecule and T-cell receptors (TCRs). Tyr-3, Tyr-5, and Leu-8 were the positions in the peptide found to be H-2Kb contact residues by analyzing single alanine-substituted peptides in a competition assay with a Kb-restricted antigenic nonapeptide of Sendai virus. Arg-1, Gly-2, Val-4, Gln-6, and Gly-7 of the peptide were identified as putative TCR contact residues by testing the peptide analogs for their capacity to sensitize targets for VSV-specific cytolytic T-lymphocyte clones. The octamer N52-59 was the optimal length of the peptide required for binding to Kb. This peptide length requirement and the finding of an irregular interspersing of major histocompatibility complex and TCR contact residues are most consistent with the conclusion that the peptide is in an extended conformation in the antigen binding groove. Furthermore, data on binding of truncated peptides show that, although the Arg-1 side chain has been assigned as a TCR contact residue, the main-chain atoms of the N-terminal amino group are most likely involved in interacting with the major histocompatibility complex molecule. A panel of H-2Kb point mutants was constructed to explore the effect of altered amino acid residues on the binding of N52-59. Mutants with amino acid substitutions along the floor of the groove all bound the VSV peptide but modulated its interaction with Kb, apparently causing subtle changes in the spatial arrangement of some specific TCR contact residues in the peptide.

Amino Acid Sequence↗
PubMed1992

A polymorphic human kidney-specific non-MHC alloantigen. Its possible role in tissue-specific allograft immunity.

Tissue specific non-MHC alloantigens play a crucial role in allograft immunity. However, their structural properties have remained elusive, largely due to their inability to induce a strong antibody response. We report the characterization of a monkey heteroantiserum, MHK-I, raised against human kidney cells, that serologically reacts specifically with kidney cells after extensive absorptions of anti-HLA class I and II reactivities. The non-MHC MHK-I-binding molecule(s) is expressed only in the renal cortex on the glomerulus, peritubular capillaries, venous endothelium, and tubular epithelium. Immunochemically, MHK-I recognizes a kidney-specific non-MHC alloantigen of Mr 90,000 to 100,000 (90 kD). These properties of MHK-I are similar to those of the previously characterized alloantibodies eluted from rejected kidneys. These alloantibodies bind to the kidney from which the antibody was eluted and to a few others but are unlike MHK-I, which binds to extracts prepared from all human kidneys. Biochemical analysis by two-dimensional electrophoresis (pI ranging between 4.5 and 5.5) and peptide fingerprinting provide further evidence that the alloantigen is polymorphic. These findings imply that the non-MHC kidney-specific molecule(s) may function as target(s) for immune destruction of renal allografts.

Animals↗
PubMed1988

Characterization of kidney cell-specific, non-major histocompatibility complex alloantigen using antibodies eluted from rejected human renal allografts.

Previous studies from our laboratories (1) have indicated that eluates prepared from rejected kidneys have antibodies not only reactive to MHC class I and class II antigens but also to antigens unique for monocytes, endothelial cells, and kidney cells. To further define the serological and biochemical nature of antigens detected by the antibodies eluted from rejected kidneys, 13 eluates prepared from rejected renal allografts and two eluates from normal kidneys were absorbed with pooled platelets, normal splenic leukocytes and/or B cells from chronic lymphocytic leukemia patients. All of the eluates failed to react with normal T and B lymphocytes by microcytotoxicity and immunofluorescence assays. However, the eluates from rejected kidneys, but not normal kidneys, reacted with peripheral blood monocytes, endothelial cells cultured from umbilical cord as well as primary kidney cells. Detailed immunohistochemical analysis of frozen kidney sections showed that the eluates from rejected kidneys reacted with structures of the cortex while sparing the structures in the medullary region. All eluates bound to the glomerulus with intense fluorescence, but not to the mesangium and Bowman's capsule, while binding to interstitial capillaries, venous endothelium, and tubular epithelium varied. More significantly, none of the eluates reacted with frozen sections of the liver, spleen, or lymph node including the endothelial lining of blood vessels in these organs. Thus, the data indicate that the eluates prepared from rejected kidneys are recognizing organ-specific antigens expressed on the kidney cells. To identify the alloantigen(s) recognized by the eluted antibodies, an immunoblot analysis was performed against phase separated membrane proteins isolated from cortical kidney cells solubilized in 2X precondensed Triton X-114. A protein of Mr. 90,000-100,000 was identified as the target non-MHC antigen to which the eluates prepared from rejected allografts were reactive. Furthermore, our results suggest a possible polymorphism among these antigens.

Endothelium, Vascular↗
PubMed1986

Asymmetry of the odontoid-lateral mass interspaces: a radiographic finding of questionable clinical significance.

Asymmetry of the interspaces between the odontoid process and the lateral masses of the atlas is a finding occasionally noted on anteroposterior open-mouth radiographs obtained following trauma. Controversy exists as to the clinical significance of this finding in minimally symptomatic patients. Some believe this asymmetry is a normal variant, while others suggest that pathological rotation of the atlas on the axis may be present. This condition has been termed atlantoaxial rotatory subluxation (ARS), and when not corrected by 15 degrees head rotation, is said to be "fixed." Recent experience has shown that some patients with radiographic findings of ARS do not exhibit clinical signs or symptoms, leading us to question the significance of the radiographic diagnosis. A study was performed to evaluate the incidence of atlantoaxial asymmetry in normal subjects, the effect of rotation on the atlantoaxial relationship, and the ability to correct asymmetry by rotation. Eleven normal volunteers were evaluated with the following anteroposterior open-mouth views: without tilt or rotation (neutral); 15 degrees rotation in each direction; 15 degrees head and neck tilt to the right; right rotation with right tilt; and left rotation with right tilt. Six normals (54%) demonstrated atlantoaxial asymmetry in the neutral position despite proper positioning. No predictable change in the atlantoaxial relationship was produced by any of the manipulations described. Two normal subjects fulfilled the radiographic criterion for fixed atlantoaxial subluxation (asymmetry not corrected by rotation). We conclude that the radiographic finding of atlantoaxial asymmetry is common and not in itself abnormal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

A retrospective evaluation of psychosocial impact of long-term growth hormone therapy.

Fifty-eight growth hormone (hGH) deficient adults who had received long-term hGH therapy and their families were contacted to assess their past and current status regarding peer relationships, educational and vocational achievements, and self-concepts. Both heterosexual and same-sex peer relationships were reported as troublesome; most reported problems with having been treated as younger than their chronologic ages. The majority reported average or above average academic performance; there were no significant differences between academic achievements of the expatients and their siblings; the greatest portion of the sample were employed at least part-time and were satisfied with their employment status. On self-concept measures, the sample rated themselves higher in self-satisfaction, personal work, and sociality, but lower on physical self and self-criticism than norms; most of the parents reported no significant differences between the patients' adjustment and that of their siblings. In addition, the recommendations from the group to others considering hGH treatment and to medical personnel working with such families are noted; implications for hGH intervention are discussed.

Adolescent↗
PubMed1978

The use of serial carcinoembryonic antigen determinations to predict recurrence of carcinoma of the colon and the time for a second-look operation.

Our patients have demonstrated that serial carcinoembryonic antigen determinations contributed to the detection of recurrent tumor and that shortening the delay between carcinoembryonic antigen elevation and reoperation has resulted in an increase from 27 to 78 per cent in instances of resectable recurrent tumor encountered. If these results continue to be substantiated, the carcinoembryonic antigen assay has made a significant contribution in the control of this disease. Serial carcinoembryonic antigen assays should be performed every two months. All benign inflammatory conditions that cause carcinoembryonic antigen elevations must be searched for, and ruled out, before reoperation is decided upon. The physician must be cognizant not only of the significance of the assay but also of the limitations, and he must rely heavily on his clinical judgment.

Adenocarcinoma↗
PubMed1977

Immunoglobulins in the jejunal mucosa in adult coeliac disease and dermatitis herpetiformis after the reintroduction of dietary gluten.

Cells containing immunoglobulin (IgA, IgG, IgM) have been measured and the distribution of extracellular and epithelial cell immunoglobulin assessed in treated patients with adult coeliac disease (ACD) and dermatitis herpetiformis (DH) before and after gluten was reintroduced to the diet. Patients with ACD and DH frequently had IgM and IgG cells above the normal range even before re-exposure to gluten, although the range of IgA cells was normal. In both diseases IgA and IgM cells increased after gluten with a proportionally greater rise in the latter, so that numbers of IgM cells, but not of IgA, exceeded the control range in all but one patient. There were increased quantities of IgA and IgM extracellularly in the lamina propria and in epithelial cells after challenge with gluten. Third component of complement was also found in some biopsies after re-exposure to gluten. These findings support the suggestion that gluten induces a humoral immunological response within the small intestinal mucosa and that both IgA and IgM systems are involved.

Adult↗