Ligand-Receptor Interactions

The formation and dissociation of specific noncovalent interactions between a variety of macromolecules play a crucial role in the function of biological systems. During the last few years, three main lines of research led to a dramatic improvement of our understanding of these important phenomena. First, combination of genetic engineering and X ray cristallography made available a simultaneous knowledg of the precise structure and affinity of series or related ligand-receptor systems differing by a few well-defined atoms. Second, improvement of computer power and simulation techniques allowed extended exploration of the interaction of realistic macromolecules. Third, simultaneous development of a variety of techniques based on atomic force microscopy, hydrodynamic flow, biomembrane probes, optical tweezers, magnetic fields or flexible transducers yielded direct experimental information of the behavior of single ligand receptor bonds. At the same time, investigation of well defined cellular models raised the interest of biologists to the kinetic and mechanical properties of cell membrane receptors. The aim of this review is to give a description of these advances that benefitted from a largely multidisciplinar approach

Retail innovation and shopping practices: consumers' reaction to self-service retailing

Authors' draft also available on Surrey eprints repository at http://epubs.surrey.ac.uk. Final version available online at http://www.envplan.com/In this paper we address the related issues of retail innovation, changing shopping practices, and shopping geographies. We do so in relation to the spread of self-service grocery stores, and particularly the supermarket, in the postwar retail environment of Britain (1950 – 70), arguing that this juncture provides a propitious opportunity to study the relationship between changing practices of retailing and consumption. We highlight shoppers’ selective adoption of new self-service formats in relation to certain product categories and argue that this can be explained in part by reference to the socially embedded nature of women food shoppers’ behaviours and in particular the influence of contemporary notions of the ‘good housewife’. We support our argument by reference to a wide range of contemporary documentary material relating to postwar shopping including market research reports, the publications of local consumer groups, and selected retailer and government archive sources

Nano-motion Dynamics are Determined by Surface-Tethered Selectin Mechanokinetics and Bond Formation

The interaction of proteins at cellular interfaces is critical for many biological processes, from intercellular signaling to cell adhesion. For example, the selectin family of adhesion receptors plays a critical role in trafficking during inflammation and immunosurveillance. Quantitative measurements of binding rates between surface-constrained proteins elicit insight into how molecular structural details and post-translational modifications contribute to function. However, nano-scale transport effects can obfuscate measurements in experimental assays. We constructed a biophysical simulation of the motion of a rigid microsphere coated with biomolecular adhesion receptors in shearing flow undergoing thermal motion. The simulation enabled in silico investigation of the effects of kinetic force dependence, molecular deformation, grouping adhesion receptors into clusters, surface-constrained bond formation, and nano-scale vertical transport on outputs that directly map to observable motions. Simulations recreated the jerky, discrete stop-and-go motions observed in P-selectin/PSGL-1 microbead assays with physiologic ligand densities. Motion statistics tied detailed simulated motion data to experimentally reported quantities. New deductions about biomolecular function for P-selectin/PSGL-1 interactions were made. Distributing adhesive forces among P-selectin/PSGL-1 molecules closely grouped in clusters was necessary to achieve bond lifetimes observed in microbead assays. Initial, capturing bond formation effectively occurred across the entire molecular contour length. However, subsequent rebinding events were enhanced by the reduced separation distance following the initial capture. The result demonstrates that vertical transport can contribute to an enhancement in the apparent bond formation rate. A detailed analysis of in silico motions prompted the proposition of wobble autocorrelation as an indicator of two-dimensional function. Insight into two-dimensional bond formation gained from flow cell assays might therefore be important to understand processes involving extended cellular interactions, such as immunological synapse formation. A biologically informative in silico system was created with minimal, high-confidence inputs. Incorporating random effects in surface separation through thermal motion enabled new deductions of the effects of surface-constrained biomolecular function. Important molecular information is embedded in the patterns and statistics of motion

Cellular and molecular mechanisms of immunomodulation in the brain through environmental enrichment

Recent studies on environmental enrichment (EE) have shown cytokines, cellular immune components [e.g., T lymphocytes, natural killer (NK) cells], and glial cells in causal relationship to EE in bringing out changes to neurobiology and behavior. The purpose of this review is to evaluate these neuroimmune mechanisms associated with neurobiological and behavioral changes in response to different EE methods. We systematically reviewed common research databases. After applying all inclusion and exclusion criteria, 328 articles remained for this review. Physical exercise (PE), a form of EE, elicits anti-inflammatory and neuromodulatory effects through interaction with several immune pathways including interleukin (IL)-6 secretion from muscle fibers, reduced expression of Toll-like receptors on monocytes and macrophages, reduced secretion of adipokines, modulation of hippocampal T cells, priming of microglia, and upregulation of mitogen-activated protein kinase phosphatase-1 in central nervous system. In contrast, immunomodulatory roles of other enrichment methods are not studied extensively. Nonetheless, studies showing reduction in the expression of IL-1β and tumor necrosis factor-α in response to enrichment with novel objects and accessories suggest anti-inflammatory effects of novel environment. Likewise, social enrichment, though considered a necessity for healthy behavior, results in immunosuppression in socially defeated animals. This has been attributed to reduction in T lymphocytes, NK cells and IL-10 in subordinate animals. EE through sensory stimuli has been investigated to a lesser extent and the effect on immune factors has not been evaluated yet. Discovery of this multidimensional relationship between immune system, brain functioning, and EE has paved a way toward formulating environ-immuno therapies for treating psychiatric illnesses with minimal use of pharmacotherapy. While the immunomodulatory role of PE has been evaluated extensively, more research is required to investigate neuroimmune changes associated with other enrichment methods.Gaurav Singhal, Emily J. Jaehne, Frances Corrigan and Bernhard T. Baun

Clinical Activity of DNA Methyltransferase Inhibitors In Therapy-Related Myelodysplastic Syndromes: A Retrospective Study

Abstract Abstract 1891 Therapy-related myelodysplastic syndrome (tMDS) is a poor-risk subtype of MDS with no standard treatment options, and yet patients (pts) with tMDS are often excluded from trials where they would have the opportunity to benefit from novel treatment approaches. DNA methyltransferase inhibitors are a treatment option for tMDS, and are being evaluated as a bridge to stem cell transplant in these often heavily pre-treated patients to avoid the organ toxicity of intensive chemotherapy. However, the response rate of tMDS to DNA methyltransferase inhibitor (DNMTI) therapy is unknown. In this retrospective study, adult patients tMDS were culled from a fully annotated, IRB-approved database of all MDS patients who received either decitabine (DAC) on both the 3-day and 5-day schedules or 5-azacytidine (5-aza) at our institution from 4/8/2002 to 6/18/2010. Patients who received interrupted therapy were only analyzed for response to their initial course of therapy. Patients who received sequential DNMTI therapy (i.e., DAC followed by 5-aza or 5-aza followed by DAC) were included, but response to only their initial therapy was assessed. Responses were determined using the modified International Working Group criteria (Cheson BD, et al, 2006). Of the 35 patients initially identified with tMDS who received DNMTI therapy, 4 were deemed inevaluable for response due to marrow involvement with the primary malignancy (n= 1), missing records (n=2), or delivery of < 1 full cycle of therapy (n=1). The 31 evaluable pts included 14 males and 17 females with a median age of 65 years (range 25–85). Therapy for the primary malignancy included chemotherapy alone (n=13), chemotherapy plus radiotherapy (n=14), radioactive iodine and radiotherapy (n=2), radioactive iodine and chemotherapy (n=2), and autologous stem cell transplant (n=3). Prior to DNMTI therapy, the MDS FAB subtypes were as follows: RA, n= 6; RARS, n= 3; RAEB, n= 19; RAEBt, n=2; CMMoL, n=1. Pre-DNMTI therapy included lenalidomide (n=4) and alloSCT (n=1). Of the 31 evaluable patients, 20 received DAC, including 7 pts who received tretinoin with DAC in a clinical trial, and 11 received 5-aza. DAC recipients received a median of 2 cycles of therapy (range, 1–12) and 5-aza recipients received a median of 5 cycles (range, 1–9). Best responses were as follows: CR, n=1; Marrow CR plus HI, n=6 (3 trilineage HI, 1 HI-P+ HI-N, 2 HI-P); Stable Disease, n=6; Progressive Disease, n=6; Failures (death during 1st cycle or before response evaluation), n=3. Rate of CR + mCR was 22% (n=7). Additional patients had inevaluable (aparticulate) marrows, or refused follow-up marrow studies, but showed signs of stable (n= 3), improved, (n=2; HI-P, HI-P+HI-N), or progressive cytopenias (n= 3). Median time to best response was 1.5 cycles (range 1–6). Fifty-eight percent (n=18) of 31 pts achieved stable disease or better responses (including 4 pts with stable cytopenias or HI with inevaluable marrow response). Four patients proceeded directly to transplant after DNMTI therapy. Two subsequently died from relapsed disease after transplant, while 1 pt is lost to follow-up and 1 pt is without evidence of MDS 2.5 years after transplant. Nine pts had persistence of their primary malignancy during DNMTI therapy, and 5/9 pts required interruption or cessation of their DNMTI therapy because of progressive primary malignancy. 24/31 pts died from complications of MDS (n=5) or subsequent AML (11), complications of MDS/AML with likely contribution from their primary malignancy (n=4), infection during DNMTI nadir (n=2), GVHD post AlloSCT (n=1), or unknown reasons (n=1). Living pts (n=7; median follow-up from start of DNMTI therapy = 12.5 months, range 4.1 – 35.1 months) include 5 who are not transplant candidates. In conclusion, DNMTI therapy produced modest clinical benefit in our tMDS cohort. In some patients, persistence of the primary malignancy interfered with our ability to deliver optimal DNMTI therapy and to assess response. Although DNMTIs represent a potential therapeutic option for tMDS, treatment of a larger cohort is required to clarify the response rate of these agents in tMDS. Disclosures: Klimek: Celgene: Consultancy