PubMed Health⌕ Search

Biomedical subjects

E J Gordon

Publications and source records attributed to E J Gordon.

At least 19 recordsLinked to original sources
PubMed2006

High-throughput sample handling and data collection at synchrotrons: embedding the ESRF into the high-throughput gene-to-structure pipeline.

An automatic data-collection system has been implemented and installed on seven insertion-device beamlines and a bending-magnet beamline at the ESRF (European Synchrotron Radiation Facility) as part of the SPINE (Structural Proteomics In Europe) development of an automated structure-determination pipeline. The system allows remote interaction with beamline-control systems and automatic sample mounting, alignment, characterization, data collection and processing. Reports of all actions taken are available for inspection via database modules and web services.

Data Collection↗
PubMed2005

The care and nurture of undulator data sets.

Undulator radiation is the X-ray source of choice for modern macromolecular crystallography beamlines. Here, the basic properties of undulator sources are described and it is indicated why they make such good X-ray sources for macromolecular crystallography. Collection of excellent data from these beamlines is not always straightforward; therefore, a number of rules are postulated for undulator data collection and guidelines are offered which will help to ensure a satisfactory experiment.

Crystallization↗
PubMed2001

The C1 subunit of alpha-crustacyanin: the de novo phasing of the crystal structure of a 40 kDa homodimeric protein using the anomalous scattering from S atoms combined with direct methods.

The previously unknown crystal structure of the C(1) subunit of the carotenoid-binding protein alpha-crustacyanin has been determined using the anomalous scattering available at 1.77 A wavelength to determine the partial structure of the S atoms intrinsic to the native protein. The resulting 'heavy-atom' phases, in conjunction with near-atomic resolution (d(min) = 1.15 A) data, were then used to initiate successful structure determination using a direct-methods approach. This is, to the authors' knowledge, the first time such a small anomalous signal ( approximately 1%) has been used to aid the determination of a macromolecular structure. As well as the structure itself, the methods used during data collection and those used in the elucidation of the sulfur 'heavy-atom' partial structure are described here. As predicted, the C(1) subunit adopts a tertiary structure typical of the lipocalin superfamily: an eight-stranded antiparallel beta-barrel with a repeated +1 topology. The beta-barrel has a calyx shape with the two molecules in the asymmetric unit interacting in such a way that the open ends of each calyx face each other, although they do not form a single elongated pocket. A comparison of this structure with those of other members of the lipocalin superfamily has allowed speculation as to the nature of carotenoid binding by the protein.

Amino Acid Sequence↗
PubMed2001

Rat xenograft survival in mice treated with donor-specific transfusion and anti-CD154 antibody is enhanced by elimination of host CD4+ cells.

BACKGROUND: Treatment with a donor-specific transfusion (DST) and a brief course of anti-mouse CD154 (anti-CD40-ligand) monoclonal antibody (mAb) prolongs the survival of both allografts and rat xenografts in mice. The mechanism by which allograft survival is prolonged is incompletely understood, but depends in part on the presence of CD4+ cells and the deletion of alloreactive CD8+ T cells. Less is known about the mechanism by which this protocol prolongs xenograft survival. METHODS: We measured rat islet and skin xenograft survival in euthymic and thymectomized mice treated with combinations of DST, anti-CD154 mAb, anti-CD4 mAb, and anti-CD8 mAb. Recipients included C57BL/6, C57BL/6-scid, C57BL/6-CD4null, and C57BL/6-CD8null mice. RESULTS: Pretreatment with a depleting anti-CD4 mAb markedly prolonged the survival of both skin and islet xenografts in mice given DST plus anti-CD154 mAb. Comparable prolongation of xenograft survival was obtained in C57BL/6-CD4null recipients treated with DST and anti-CD154 mAb. In contrast, anti-CD8 mAb did not prolong the survival of either islet or skin xenografts in mice treated with DST and anti-CD154 mAb. Thymectomy did not influence xenograft survival in any treatment group. Adoptive transfer of splenocytes from C57BL/6-CD4null recipients treated with DST and anti-CD154 mAb and bearing long-term skin xenografts revealed the presence of residual xenoreactive cells. CONCLUSIONS: These data suggest that treatment with DST and anti-CD154 mAb induces a state of "functional" transplantation tolerance. They also support the hypothesis that both the induction and maintenance of graft survival based on this protocol depend on different cellular mechanisms in allogeneic and xenogeneic model systems.

Animals↗
PubMed2001

Patients' decisions for treatment of end-stage renal disease and their implications for access to transplantation.

Gaining access to kidney transplantation is a complex process that involves treatment decisions made by patients. Despite several advantages of kidney transplantation, some patients choose to remain on hemodialysis for treatment of end-stage renal disease. The present study was undertaken to describe the sociocultural factors influencing patients' decisions to remain on dialysis compared to those who sought a transplant. The study also examined whether African Americans made decisions different from European Americans which would offer insights into one of many factors resulting in them receiving disproportionately fewer kidney transplants. Using a qualitative approach supplemented by a quantitative approach, interviews employing open-ended questions and a card sort technique were conducted with 79 hemodialysis patients. Patients who preferred to remain on dialysis were significantly older and more likely to be unmarried and Protestant. The relationship between treatment decisions and ethnicity was inconclusive due to multiple, interrelated covariates. The three most common reasons patients reported for remaining on dialysis included: doing well on dialysis, fear of being "cut on" from a transplant, and knowing other patients whose kidney transplant failed. This study identified sociocultural and ethnomedical beliefs and values about the body and transplantation that inform patients' treatment decisions. This study also generated data that illuminate the complexity of patients' decisions and how these affect patients' preferences regarding transplantation. The results emphasize the need for policy makers to recognize patients' decisions when accounting for alleged difficulties in gaining access to transplantation.

Adolescent↗
PubMed2001

"They don't have to suffer for me": why dialysis patients refuse offers of living donor kidneys.

In the present climate of organ shortage, high demand for kidney transplants, and better clinical outcomes from living donors, health care professionals expect and encourage patients to accept offers of living related donor (LRD) kidneys. When patients decide not to adhere to this course of treatment, scholars and policy makers may question why, given that it delays their chances of receiving a transplant. This article reports on patients' decisions to refuse LRD kidney offers. An 18-month study was conducted of treatment decisions by hemodialysis patients (N = 79). Fewer than half of those offered an LRD kidney (N = 64) were willing to accept it, suggesting that sociocultural factors inform decisions. Patients expressed concerns about the potential donors' well-being over their own and about compromising their relationships with the donors. This article concludes that social relations, emotions, and ethnomedical beliefs play an important role in patients' treatment decisions and thus contributes to the anthropology of decision making.

Adult↗
PubMed2000

Synthesis of end-labeled multivalent ligands for exploring cell-surface-receptor-ligand interactions.

BACKGROUND: Ring-opening metathesis polymerization (ROMP) is a powerful synthetic method for generating unique materials. The functional group tolerance of ruthenium ROMP initiators allows the synthesis of a wide range of biologically active polymers. We generated multivalent ligands that inhibit cell surface L-selectin, a protein that mediates lymphocyte homing and leukocyte recruitment in inflammation. We hypothesized that these ligands function through specific, multivalent binding to L-selection. To examine this and to develop a general method for synthesizing multivalent materials with end-labels, we investigated functionalized enol ethers as capping agents in ruthenium-initiated ROMP. RESULTS: We synthesized a bifunctional molecule that introduces a unique end group by terminating ruthenium-initiated ROMP reactions. This agent contains an enol ether at one end and a masked carboxylic acid at the other. We conjugated a fluorescein derivative to an end-capped neoglycopolymer that had previously been shown to inhibit L-selection function. We used fluorescence microscopy to visualize neoglycopolymer binding to cells displaying L-selectin. Our results suggest that the neoglycopolymers bind specifically to cell surface L-selectin through multivalent interactions. CONCLUSIONS: Ruthenium-initiated ROMP can be used to generate biologically active, multivalent ligands terminated with a latent functional group. The functionalized polymers can be labeled with a variety of molecular tags, including fluorescent molecules, biotin, lipids or antibodies. The ability to conjugate reporter groups to ROMP polymers using this strategy has broad applications in the material and biological sciences.

Carbohydrates↗
PubMed2000

Patient-nephrologist discussions about kidney transplantation as a treatment option.

Little is known about how nephrologists discuss transplantation as a treatment option with end-stage renal disease patients. The authors sought to describe the content and manner of patient-nephrologist discussions about transplantation. Using a cross-sectional study design, we interviewed 79 chronic hemodialysis patients and 12 nephrologists using a semistructured questionnaire that focused on nephrologist and patient reports of discussions about transplantation. The authors found that nephrologists provided information on treatment options gradually over several weeks to months. They generally presented the option of dialysis first, then transplantation, but avoided discussing mortality data. Nephrologists said they encouraged most patients, but especially young patients, to seek transplantation. Of all patients, 68% reported being encouraged to seek transplantation by nephrologists. Low socioeconomic status patients were less likely to report being encouraged to seek transplantation even after adjustment for transplant suitability. Both nephrologists and patients avoided discussing life expectancy data. In conclusion, patient age and socioeconomic status appear to influence discussions of transplantation as a treatment option. Further work is needed to determine how the content and manner of such discussions affect treatment decisions.

Adult↗
PubMed2000

Immune responses to hepatitis C virus structural and nonstructural proteins induced by plasmid DNA immunizations.

DNA-based immunizations have been used to elicit cellular immunity to hepatitis C virus (HCV) proteins in mice. Mice were immunized by intramuscular or intradermal injections of plasmid DNA derived from a near-full-length HCV genotype 1b genomic clone (pRC/B2) or individual genomic clones. These immunizations induced cytotoxic T lymphocytes (CTLs), as revealed in standard chromium-release assays that used syngeneic peptide-pulsed or transfected target cells. These assays identified four CTL epitopes within the capsid, E1, and E2 regions of the polyprotein sequence of HCV genotype 1a that were cross-reactive with HCV genotype 1b. Additionally, CTLs derived from mice immunized with either NS3 or NS5 specifically lysed target cells sensitized to either the genotype 1a or 1b gene products. Nucleic acid immunizations also generated humoral immunity to HCV proteins, as detected by anti-HCV reactivity to NS3 and capsid in ELISAs and immunoblot assays.

Animals↗
PubMed1999

Inhibition of L-selectin-mediated leukocyte rolling by synthetic glycoprotein mimics.

Synthetic carbohydrate and glycoprotein mimics displaying sulfated saccharide residues have been assayed for their L-selectin inhibitory properties under static and flow conditions. Polymers displaying the L-selectin recognition epitopes 3',6-disulfo Lewis x(Glc) (3-O-SO3-Galbeta1alpha4(Fucalpha1alpha3)-6-O-SO3-Glcbeta+ ++-OR) and 3',6'-disulfo Lewis x(Glc) (3, 6-di-O-SO3-Galbeta1alpha4(Fucalpha1alpha3)Glcbeta-OR) both inhibit L-selectin binding to heparin under static, cell-free binding conditions with similar efficacies. Under conditions of shear flow, however, only the polymer displaying 3',6-disulfo Lewis x(Glc) inhibits the rolling of L-selectin-transfected cells on the glycoprotein ligand GlyCAM-1. Although it has been shown to more effective than sialyl Lewis x at blocking the L-selectin-GlyCAM-1 interaction in static binding studies, the corresponding monomer had no effect in the dynamic assay. These data indicate that multivalent ligands are far more effective inhibitors of L-selectin-mediated rolling than their monovalent counterparts and that the inhibitory activities are dependent on the specific sulfation pattern of the recognition epitope. Importantly, our results indicate the L-selectin specificity for one ligand over another found in static, cell-free binding assays is not necessarily retained under the conditions of shear flow. The results suggest that monovalent or polyvalent carbohydrate or glycoprotein mimetics that inhibit selectin binding in static assays may not block the more physiologically relevant process of selectin-mediated rolling.

Animals↗
PubMed1999

NOD mice have a generalized defect in their response to transplantation tolerance induction.

A protocol consisting of a single donor-specific transfusion (DST) plus a brief course of anti-CD154 monoclonal antibody (anti-CD40 ligand mAb) induces permanent islet allograft survival in chemically diabetic mice, but its efficacy in mice with autoimmune diabetes is unknown. Confirming a previous report, we first observed that treatment of young female NOD mice with anti-CD154 mAb reduced the frequency of diabetes through 1 year of age to 43%, compared with 73% in untreated controls. We also confirmed that spontaneously diabetic NOD mice transplanted with syngeneic (NOD-Prkdc(scid)/Prkdc(scid)) or allogeneic (BALB/c) islets rapidly reject their grafts. Graft survival was not prolonged, however, by pretreatment with either anti-CD154 mAb alone or anti-CD154 mAb plus DST. In addition, allograft rejection in NOD mice was not restricted to islet grafts. Anti-CD154 mAb plus DST treatment failed to prolong skin allograft survival in nondiabetic male NOD mice. The inability to induce transplantation tolerance in NOD (H2g7) mice was associated with non-major histocompatibility complex (MHC) genes. Treatment with DST and anti-CD154 mAb prolonged skin allograft survival in both C57BL/6 (H2b) and C57BL/6.NOD-H2g7 mice, but it was ineffective in NOD, NOD.SWR-H2q, and NOR (H2g7) mice. Mitogen-stimulated interleukin-1beta production by antigen-presenting cells was greater in strains susceptible to tolerance induction than in the strains resistant to tolerance induction. The results suggest the existence of a general defect in tolerance mechanisms in NOD mice. This genetic defect involves defective antigen-presenting cell maturation, leads to spontaneous autoimmune diabetes in the presence of the H2g7 MHC, and precludes the induction of transplantation tolerance irrespective of MHC haplotype. Promising islet transplantation methods based on overcoming the alloimmune response by interference with costimulation may require modification or amplification for use in the setting of autoimmune diabetes.

Animals↗
PubMed1998

Long-term survival of skin allografts induced by donor splenocytes and anti-CD154 antibody in thymectomized mice requires CD4(+) T cells, interferon-gamma, and CTLA4.

Treatment of C57BL/6 mice with one transfusion of BALB/c spleen cells and anti-CD154 (anti-CD40-ligand) antibody permits BALB/c islet grafts to survive indefinitely and BALB/c skin grafts to survive for approximately 50 d without further intervention. The protocol induces long-term allograft survival, but the mechanism is unknown. We now report: (a) addition of thymectomy to the protocol permitted skin allografts to survive for > 100 d, suggesting that graft rejection in euthymic mice results from thymic export of alloreactive T cells. (b) Clonal deletion is not the mechanism of underlying long-term graft survival, as recipient thymectomized mice were immunocompetent and harbor alloreactive T cells. (c) Induction of skin allograft acceptance initially depended on the presence of IFN-gamma, CTLA4, and CD4(+) T cells. Addition of anti-CTLA4 or anti-IFN-gamma mAb to the protocol was associated with prompt graft rejection, whereas anti-IL-4 mAb had no effect. The role of IFN-gamma was confirmed using knockout mice. (d) Graft survival was associated with the absence of IFN-gamma in the graft. (e) Long-term graft maintenance required the continued presence of CD4(+) T cells. The results suggest that, with modification, our short-term protocol may yield a procedure for the induction of long-term graft survival without prolonged immunosuppression.

Abatacept↗
PubMed1998

Parental leave: comparing children's hospitals with Fortune 500 companies.

OBJECTIVE: To identify parental leave policies and availability of support systems for new parents employed by children's hospitals and compare these benefits with those offered by Fortune 500 companies. DESIGN: Telephone or facsimile survey of all (n=118) children's hospitals and pediatric medical centers in the National Association of Children's Hospitals and Related Institutions 1995 Directory of Members, and 118 geographically matched Fortune 500 companies. Policies for maternity and paternity leave, adoption benefits, and support services for new parents were compared. RESULTS: Ninety-four children's hospitals (80%) and 82 Fortune 500 companies (69%) responded to the survey. No difference in duration of maternity (P>.30) or paternity (P=.12) leave was found. Sixty-two companies (77%) classified maternity leave as short-term disability while 47 hospitals (50%) classified it as sick time (P<.005). Classifying maternity leave as short-term disability generally gives better benefits to employees with short duration of service, whereas classifying maternity leave as sick time usually favors employees with longer employment. Companies provided more financial support for adoption expenses (P<.05), but there was no difference in duration of paid or unpaid leave for adoption (P=.14). Hospitals provided more on-site day care (69% vs 42%; P<.001) and better support systems for breast-feeding mothers (49% vs 24%; P<.002). CONCLUSIONS: Children's hospitals do not offer better parental leave benefits than Fortune 500 companies; however, they offer better support systems for parents returning to work after the birth of a child.

Commerce↗
PubMed1998

Glycoprotein-inspired materials promote the proteolytic release of cell surface L-selectin.

The proteolytic release, or shedding, of a cell surface protein can serve a regulatory role; the process liberates a soluble form of the protein into circulation while downregulating its cell surface concentration. The characteristics that render a protein susceptible to proteolytic cleavage are not known. We hypothesized that the clustering of a protein at the cell surface might target it for proteolysis. To test this hypothesis, we synthesized molecules that display multiple copies of sulfated galactose residues, termed neoglycopolymers, that are designed to mimic natural ligands for the cell adhesion protein L-selectin. We found that treatment of human neutrophils with the neoglycopolymers resulted in a dose-dependent loss of L-selectin from the cell surface, while monovalent compounds and unsulfated neoglycopolymers had no effect. Because L-selectin is an important mediator in the inflammatory response, such compounds could lead to novel antiinflammatory drugs. Moreover, molecules that control receptor shedding can be used to alter cellular responsiveness to specific ligands or to promote responses at distal sites; consequently, these results have broad implications for regulating the location and presentation of important biomolecules.

Dose-Response Relationship, Drug↗