Rituxan (anti-CD20 antibody)-induced translocation of CD20 into lipid rafts is crucial for calcium influx and apoptosis

Rituxan, a chimeric anti-CD20 antibody, is the first antibody approved for immunotherapy in non-Hodgkin's B-cell lymphoma and other B-cell lymphoproliferative disorders. Additionally, efficacy of Rituxan treatment has been reported in nonmalignant autoimmune diseases such as rheumatoid arthritis. Crosslinking of CD20 molecules by Rituxan induces therapeutic B-cell depletion. CD20 is a B-lymphocyte specific integral membrane protein, proposed to function as a store-operated calcium channel, which is activated upon receptor-stimulated calcium depletion of intracellular stores. Crosslinking of CD20 by antibodies has been reported to induce a redistribution of CD20 molecules to specialized microdomains at the plasma membrane known as lipid rafts. Here, we report that in the absence of Rituxan, CD20 exhibits a low affinity to lipid rafts. However, binding of Rituxan significantly increases the affinity of CD20 for lipid rafts resulting in its redistribution to a fraction resistant to Triton X-100 solubilization. Furthermore, we demonstrate that disturbing the raft integrity by cholesterol extraction results in dissociation of CD20 from a Triton X-100 resistant fraction followed by complete inhibition of Rituxan-induced calcium entry and apoptosis. The integrity of lipid rafts seems to play a crucial role for CD20-induced caspase activation. These data show, for the first time, that Rituxan-induced translocation of CD20 to lipid rafts is important for increased intracellular Ca(2+) levels and downstream apoptotic signalling.

Monomeric and Multimeric Blockers of Selectins: Comparison of in vitro and in vivo Activity

The potency of the oligosaccharides SiaLe(x), SiaLe(a), HSO(3)Le(x), and HSO(3)Le(a), their conjugates with polyacrylamide (PAA, 40 kD), and other monomeric and polymeric selectin inhibitors has been compared with that of the polysaccharide fucoidan. The following assay systems were used: 1) a 96-well assay based either on the use of recombinant E-, P-, and L-selectins or an analogous assay with natural P-selectin isolated from human platelets; 2) a platelet-based P-selectin cell assay; and 3) a rat model of peritoneal inflammation. IC(50) values for the neoglycoconjugate SiaLe(a)-PAA were 6, 40, and 85 microM for recombinant E-, P-, and L-selectins, respectively; all monomeric inhibitors were about two orders of magnitude weaker. PAA-conjugates, containing as a ligand tyrosine-O-sulfate (sTyr) in addition to one of the sialylated oligosaccharides, were the most potent synthetic blockers in vitro. Compared with fucoidan, the most potent known P- and L-selectin blocker, the bi-ligand glycoconjugate HSO(3)Le(a)-PAA-sTyr displayed similar inhibitory activity in vitro towards L-selectin and about ten times lower activity towards P-selectin. All of the tested synthetic polymers displayed a similar ability to inhibit neutrophil extravasation in the peritonitis model (in vivo) at 10 mg/kg. The data provide evidence that monomeric SiaLe(x) is considerably more effective as a selectin blocker in vivo than in vitro, whereas the opposite is true for fucoidan and the bi-ligand neoglycoconjugate HSO(3)Le(a)-PAA-sTyr.

Modulation of sialyl Lewis X dependent binding to E-selectin by glycoforms of alpha-1-acid glycoprotein expressed in rheumatoid arthritis

Alpha-1-acid glycoprotein (AGP) is an extensively glycosylated acute phase protein of imprecisely defined physiological function. Nonetheless it is known that the oligosaccharide component comprising 42% of the 41 kDa molecular weight is critical to the previously described multifarious immunomodulatory functions of AGP in vitro. Complex oligosaccharides were enzymically released from AGP purified from the blood of rheumatoid arthritis sufferers by our oligosaccharide protective method. Oligosaccharide profiling was by means of high pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Monosaccharide composition analysis revealed increased fucosylation of inflammatory AGP oligosaccharide chains, suggesting the potential for expression of the tetrasaccharide antigen and E-Selectin ligand, sialyl Lewis X (sLeX). The hypothesis that AGP may function to inhibit blood cell binding to activated endothelium at E-Selectin was tested in a microtitre cell-protein binding assay. In this system we have shown that the oligosaccharide moiety of AGP, as expressed in inflammatory disease, can inhibit the sLeX/E-Selectin interaction. Thus we have identified a correlation between the abnormal glycosylation of AGP in rheumatoid arthritis and suppression of sLeX dependent cell adhesion through inhibition of E-selectin binding which could be the basis of a novel, site specific, anti-inflammatory agent.

Characterization of E-selectin-binding epitopes expressed by skin-homing T cells

The glycoprotein counter-receptors for E-selectin borne on skin-homing T cells are poorly defined. In this study we have used flow cytometry to investigate the surface expression of potential carbohydrate ligands for E-selectin on HUT78, a skin-homing cutaneous T-cell lymphoma. These cells possessed high surface expression of the KM-93 epitope but not HECA 452 or CSLEX1 epitopes. The KM-93 antibody also blocked the binding of HUT78 cells to E-selectin. All these antibodies are reported to recognize sialyl Lewis X (sLex)-like molecules. Using an E-selectin affinity matrix, the main glycoprotein isolated from HUT78 cells was a molecular species of 90 000 MW. Other minor species of molecular weights 40 000, 60 000, 100 000, 120 000 and 200 000 were also identified as potential counter-receptors for E-selectin. Four of the purified counter-receptors (90 000, 100 000, 120 000 and 200 000 MW) stained positive with the KM-93 antibody. Immunoblot analysis of these purified glycoproteins established the identity of the 90 000 MW glycoprotein as l-selectin. Furthermore, an anti-l-selectin antibody inhibited the binding of HUT78 cells to E-selectin, probably by steric inhibition of the carbohydrate ligand for E-selectin that is borne on the C-type lectin domain of l-selectin. These results suggest that a carbohydrate epitope on l-selectin may act as a ligand for E-selectin on skin-homing T cells.

Scintillation proximity assay for E-, P-, and L-selectin utilizing polyacrylamide-based neoglycoconjugates as ligands

In this study, a novel scintillation proximity assay (SPA) that uses radiolabeled soluble neoglycoconjugates as synthetic alternatives to the natural E-, P-, and L-selectin counterligands was developed. The neoglycoconjugates contained sialyl LewisX or sialyl LewisA attached via a three-carbon spacer to a poly[N-(hydroxyethyl)acrylamide] backbone, thus presenting the carbohydrates in a multivalent form. Selectin-ZZ fusion proteins were immobilized on anti-rabbit IgG-coated SPA beads via a rabbit IgG bridge. The neoglycoconjugate ligands bound to all three bead-immobilized selectins, with the highest binding levels apparent with E-selectin. Saturation binding studies with E-selectin revealed a complex interaction indicative of two or more binding affinities. The response to carbohydrate inhibitors was comparable in E-selectin assays that used either the neoglycoconjugates or the tritium-labeled HL60 cells as selectin counterligands. The incorporation of tyrosine sulfate groups into the backbone of the neoglycoconjugate resulted in enhanced binding avidity to both P- and L-selectin, indicating that the sulfate-containing neoglycoconjugates are viable synthetic mimics of the natural P- and L-selectin counterligands. The use of these radiolabeled neoglycoconjugates in conjunction with SPA results in a format ideally suited for the high-throughput screening for selectin antagonists. Furthermore, this approach can potentially be used to measure other low-avidity lectin-carbohydrate interactions.

P-selectin binds to bacterial lipopolysaccharide

Multiple organ failure associated with disseminated intravascular coagulation is a frequent complication in septic shock patients. Accumulation of platelets and neutrophils in the organs contributes to the manifestation of lipopolysaccharide (LPS)-induced organ failure. Although a direct interaction between LPS and platelets is well documented, the nature of the surface receptor for LPS on platelets is unknown. In this article we show that P-selectin is a receptor for LPS. The binding of LPS to P-selectin is independent of Ca2+, and is blocked by antibodies to P-selectin, lipid A and fucoidan. Platelets pre-treated with thrombin showed fourfold higher binding of fluorescein isothiocyanate (FITC)-conjugated LPS compared to untreated platelets and the binding of FITC-conjugated LPS to platelets was blocked in the presence of anti-P-selectin antibodies. It is likely that the binding of LPS via P-selectin on activated platelets or epithelium could have a significant role in the pathophysiology of organ failure in septic shock.

Role for L-selectin in lipopolysaccharide-induced activation of neutrophils

The activation of leucocytes by bacterial cell wall lipopolysaccharide (LPS) contributes to the pathogenesis of septic shock. LPS is known to interact with several cell-surface proteins, including CD14, when presented as a complex with serum LPS-binding protein. However, the identity of the receptor responsible for LPS signalling and leucocyte activation is unknown. Interestingly, mice deficient in cell-surface L-selectin were dramatically resistant to the lethal effects of high doses of LPS in a model of septic shock. Recently we reported that L-selectin binds to cardiolipin and other charged phospholipids at a site distinct from the carbohydrate-binding site. Structural similarities between charged phospholipids and the lipid A moiety of LPS prompted us to investigate interactions between L-selectin and LPS. Herein we show that L-selectin is a neutrophil surface receptor for LPS and lipotechoic acid. The binding of LPS to L-selectin is independent of serum and Ca2+, and is blocked by antibodies to L-selectin and fucoidan. Furthermore, the interaction of LPS with cell-surface L-selectin results in superoxide production, indicating that L-selectin can mediate both binding and activation of human neutrophils. These findings suggest novel therapeutic approaches for the treatment of septic shock.

Mimics of the sialyl Lewis X tetrasaccharide. Replacement of the N-acetylglucosamine sugar with simple C2-symmetric 1,2-diols

Analogues of sialyl Lewis X have been synthesized that feature replacement of the N-acetylglucosamine residue with C2-symmetric diols. The diols used contain different levels of torsional constraint and various functional groups. The cyclohexyl derived compound 27 was equipotent to sLex in vitro (IC50 0.5 mM).

Antidepressants and drug-metabolizing enzymes--expert group report

Antidepressant drugs are extensively metabolized. Consequently, the biotransformation pattern of antidepressants has an important influence on their clinical properties, i.e., pharmacokinetics, toxicity, drug-drug interactions, side-effect profile and last but not least therapeutic efficacy. It was against this background that a multidisciplinary group of experts discussed the clinical relevance of the rapidly increasing body of knowledge of antidepressant-metabolizing enzymes. The variability of the response of a given individual to an antidepressant is determined genetically and by the environment. Genetic polymorphism of drug-metabolizing enzymes and inhibition by other substrates may affect the enzymatic biotransformation of antidepressants. In vitro assay techniques allow an estimation of the potential variability in clinical response to antidepressants and a reasonable prediction of the drug-drug interaction patterns. The results of in vitro tests should therefore be considered early in the development of an antidepressant as a background for designing clinical studies (treatment schedules and dosing). Physicians should have an understanding of the relevance of genetic polymorphism for clinical practice. Education is needed in order to fill the existing gaps in knowledge about antidepressant-enzyme interactions and their application in daily treatment practice. The information on potential drug interactions determined by genetic polymorphism and based on studies with enzymes should be increasingly contained in drug compendia.

Training needs analysis within the community

A project was undertaken to provide a description of the training needs of agencies who are partners in the provision of care in the community. In developing the research strategy a service design approach was adopted which complied with the design control requirement of the Quality Standard EN ISO 9001: 1994. A questionnaire for self-completion was sent to 25 individuals involved in delivering community care. The findings enabled priorities of joint training to be identified. The findings also enabled training to be suggested for both manager and direct care staff. Demonstrates the need for skill acquisition in a variety of areas. Generally it was indicated by respondents that planning training arising from the project should be multidisciplinary. Enthusiasm for such training was also a feature of the respondents' responses.

Comparison of prevalence of schizophrenia among residents of hostels for homeless people in 1966 and 1992

OBJECTIVE

To determine whether the prevalence of schizophrenia among the homeless population of Edinburgh resident in hostels has changed between 1966 and 1992.

DESIGN

Comparison of two cross sectional surveys.

SETTINGS

Hostels for homeless people in Edinburgh.

SUBJECTS

In 1966 a random sample of 98 residents of three common lodging houses. In 1992 a random sample of 198 residents of nine hostels.

MAIN OUTCOME MEASURE

Prevalence of schizophrenia.

RESULTS

The prevalence of schizophrenia in 1992 was 12/136 (9%) compared with 20/79 (25%) in 1966 (odds ratio 0.29; 95% confidence interval 0.13 to 0.62; P = 0.001). Adjustment for confounding by age, current hostel, and duration of unemployment by means of logistic regression produced an adjusted odds ratio of 0.22 (0.08 to 0.58).

CONCLUSIONS

The prevalence of schizophrenia was lower in 1992 even after other changes in the population resident in hostels occurring between 1966 and 1992 were taken into account. The findings are not consistent with an increase in the prevalence of schizophrenia among homeless people despite a 66% reduction in adult psychiatric beds in the region during 1966-92.

Management of Alcohol Abusing Patients in Accident and Emergency Departments

A pilot study was undertaken in the Accident & Emergency (A & E) departments of two central London teaching hospitals to determine if patients who were abusing alcohol and had not received any prior medical treatment or counselling for their drinking problem were amenable to offers of help. During the 24-month study period 104 patients were identified as having a previously untreated alcohol problem, and of these 46% attended an appointment to discuss their drinking habits. The group identified was much smaller than would be expected from the number attending the A & E departments during the study period and the reasons for this are discussed. However, the important observation from the study is that almost half the patients identified as having an alcohol problem returned to the department the following day to seek advice. This suggests that A & E departments are an appropriate place to offer patients initial help about their drinking habits.

Tumor necrosis factor mediates autocrine growth inhibition in a chronic leukemia

Autocrine production of growth factors may contribute to the rapid and fatal proliferation of acute hematologic malignancies. We have investigated whether the more controlled growth of less aggressive malignancies such as chronic myeloid leukemia (CML) may be associated with autocrine production of growth inhibitory factors. TNF inhibits the growth of both normal and leukemic hemopoietic progenitor cells. We find that exogenous TNF reduces the viability and DNA synthesis of purified myeloid cells from patients with CML and inhibits myeloid colony formation by patient progenitor cells. However, unlike progenitor cells from normal donors, patient myeloid progenitor cells also constitutively express mRNA for TNF and secrete functional TNF protein in culture. This endogenous TNF impedes the growth of CML cells because anti-TNF mAb shown to neutralize bioactive human TNF increases CML cell DNA synthesis whereas non-neutralizing anti-TNF mAb has no effect. Production of TNF by CML cells is not associated with production of lymphotoxin (TNF-beta), IL-1 or IL-6. TNF-mediated autocrine growth inhibition may contribute to the maintenance of the stable, chronic phase of this disease and similar mechanisms may operate in other malignancies to limit tumor proliferation. Competition between autocrine growth promoting and inhibiting factors may underlie the observed differences in biologic behavior between acute and chronic malignancies.

Tumor necrosis factor mediates autocrine growth inhibition in a chronic leukemia

Autocrine production of growth factors may contribute to the rapid and fatal proliferation of acute hematologic malignancies. We have investigated whether the more controlled growth of less aggressive malignancies such as chronic myeloid leukemia (CML) may be associated with autocrine production of growth inhibitory factors. TNF inhibits the growth of both normal and leukemic hemopoietic progenitor cells. We find that exogenous TNF reduces the viability and DNA synthesis of purified myeloid cells from patients with CML and inhibits myeloid colony formation by patient progenitor cells. However, unlike progenitor cells from normal donors, patient myeloid progenitor cells also constitutively express mRNA for TNF and secrete functional TNF protein in culture. This endogenous TNF impedes the growth of CML cells because anti-TNF mAb shown to neutralize bioactive human TNF increases CML cell DNA synthesis whereas non-neutralizing anti-TNF mAb has no effect. Production of TNF by CML cells is not associated with production of lymphotoxin (TNF-beta), IL-1 or IL-6. TNF-mediated autocrine growth inhibition may contribute to the maintenance of the stable, chronic phase of this disease and similar mechanisms may operate in other malignancies to limit tumor proliferation. Competition between autocrine growth promoting and inhibiting factors may underlie the observed differences in biologic behavior between acute and chronic malignancies.

Demonstration of cytokines in biological medicines produced in mammalian cell lines

Commercially produced biological medicines may contain cytokines secreted by mammalian cell lines. Several such cell lines were found to produce interleukin 6 and, after stimulation, to secrete interleukin 1, tumour necrosis factor, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor. High levels of interleukin 6 were detected in several vaccines and rDNA-derived proteins, and certain vaccines contained interleukin 1, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor. Some preparations of human monoclonal antibodies were also found to contain interleukin 1 and tumour necrosis factor. Cytokines may contribute to certain types of adverse reactions to these products.

Elimination of drift in a single-mode optical fiber interferometer using a piezoelectrically stretched coiled fiber

The feasibility of maintaining a single-mode optical fiber interferometer in quadrature is demonstrated using a servo driven piezoelectrically stretched coiled fiber. The controller has a range of ~10(-5)-1000 rad with a stress voltage coefficient of ~27pi rad/V.

Thermally induced optical phase effects in fiber optic sensors

Induced optical phase effects attributed to time varying temperatures at the fiber surface in single-mode fiber optic interferometric sensors are calculated. A Green's function approach is used for predicting temperature distributions within fibers for general time-dependent external temperatures. Analytic expressions for temperature distributions within fibers exposed to external linear, step, and sinusoidal temperature variations are derived using standard differential equation methods, assuming heat conduction to be the only heat transfer mechanism. With these expressions, thermally induced optical phase effects are predicted for an infinitely long uniform-index fiber. Plots are given that show the significance of fiber diameter and thermal properties on the time-dependent behavior of thermally induced phase effects for specific external temperature variations. It is shown that thermally induced phase effects can be reduced by jacketing fibers with elastomers having certain thermal properties.

The effect of CI-719 on lipolysis in rat adipose tissue

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