A controlled trial of natalizumab for relapsing multiple sclerosis.

Background: In patients with multiple sclerosis, inflammatory brain lesions appear to arise from autoimmune responses involving activated lymphocytes and monocytes. The glycoprotein (alpha)(sub 4) integrin is expressed on the surface of these cells and plays a critical part in their adhesion to the vascular endothelium and migration into the parenchyma. Natalizumab is an (alpha)(sub 4) integrin antagonist that reduced the development of brain lesions in experimental models and in a preliminary study of patients with multiple sclerosis.Methods: In a randomized, double-blind trial, we randomly assigned a total of 213 patients with relapsing-remitting or relapsing secondary progressive multiple sclerosis to receive 3 mg of intravenous natalizumab per kilogram of body weight (68 patients), 6 mg per kilogram (74 patients), or placebo (71 patients) every 28 days for 6 months. The primary end point was the number of new brain lesions on monthly gadolinium-enhanced magnetic resonance imaging during the six-month treatment period. Clinical outcomes included relapses and self-reported well-being.Results: There were marked reductions in the mean number of new lesions in both natalizumab groups: 9.6 per patient in the placebo group, as compared with 0.7 in the group given 3 mg of natalizumab per kilogram (P<0.001) and 1.1 in the group given 6 mg of natalizumab per kilogram (P<0.001). Twenty-seven patients in the placebo group had relapses, as compared with 13 in the group given 3 mg of natalizumab per kilogram (P=0.02) and 14 in the group given 6 mg of natalizumab per kilogram (P=0.02). The placebo group reported a slight worsening in well-being (a mean decrease of 1.38 mm on a 100-mm visual-analogue scale), whereas the natalizumab groups reported an improvement (mean increase of 9.49 mm in the group given 3 mg of natalizumab per kilogram and 6.21 mm in the group given 6 mg of natalizumab per kilogram).Conclusions: In a placebo-controlled trial, treatment with natalizumab led to fewer inflammatory brain lesions and fewer relapses over a six-month period in patients with relapsing multiple sclerosis

Specific ant-pollination in an alpine orchid and the role of floral scent in attracting pollinating ants

Several studies have recently shown that floral scent can deter ants from flowers. However, when ants serve as reliable pollen vectors, for example in harsh, windy habitats, were flying insects are less active, plants should have evolved floral signals to attract them to the flowers. We tested this hypothesis in the alpine orchid, Chamorchis alpina. C. alpina was found to be predominantly ant pollinated, with some occasional pollination by ichneumonid wasps. In all three investigated populations, only two species of ants, Formica lemani and Leptothorax acervorum visited the flowers and removed pollinaria. These two pollinator ants were found to be among the most common ant species in all habitats, but other, non-pollinating ants were also frequently found, suggesting a factor that mediates specific pollination. Floral morphology was found to be compatible with at least one of the common non-pollinator ants. Floral scent consistently comprised five terpenoid compounds, β-phellandrene, 1,8-cineole, linalool, α-terpineol, and β-caryophyllene. A synthetic blend of these five compounds emitting from rubber septa, was found to be attractive to one pollinator ant-species, F. lemani, in the field. The floral scent of C. alpina, through attracting only specific ants, may thus play a role in filtering floral visitors

Shedding Light on the Galaxy Luminosity Function

From as early as the 1930s, astronomers have tried to quantify the statistical nature of the evolution and large-scale structure of galaxies by studying their luminosity distribution as a function of redshift - known as the galaxy luminosity function (LF). Accurately constructing the LF remains a popular and yet tricky pursuit in modern observational cosmology where the presence of observational selection effects due to e.g. detection thresholds in apparent magnitude, colour, surface brightness or some combination thereof can render any given galaxy survey incomplete and thus introduce bias into the LF. Over the last seventy years there have been numerous sophisticated statistical approaches devised to tackle these issues; all have advantages -- but not one is perfect. This review takes a broad historical look at the key statistical tools that have been developed over this period, discussing their relative merits and highlighting any significant extensions and modifications. In addition, the more generalised methods that have emerged within the last few years are examined. These methods propose a more rigorous statistical framework within which to determine the LF compared to some of the more traditional methods. I also look at how photometric redshift estimations are being incorporated into the LF methodology as well as considering the construction of bivariate LFs. Finally, I review the ongoing development of completeness estimators which test some of the fundamental assumptions going into LF estimators and can be powerful probes of any residual systematic effects inherent magnitude-redshift data.Comment: 95 pages, 23 figures, 3 tables. Now published in The Astronomy & Astrophysics Review. This version: bring in line with A&AR format requirements, also minor typo corrections made, additional citations and higher rez images adde

Estimations of apoplastic concentrations of K+ and Ca2+ in the vicinity of stomatal guard cells.

A method which determines the null point for stomatal aperture has been used to estimate the apoplastic concentrations of potassium and calcium adjacent to the stomatal guard cells of Commelina communis. These two ions are contributors to important aspects of stomatal physiology: the determination of guard cell turgor (K+) and intracellular signalling (Ca2+) when the guard cells respond to the various stimuli that effect changes in stomatal aperture. We obtained estimates of apoplastic K+ concentrations in the range of 50–75 mol m-3, which are in general agreement with those of Bowling (1987). Ca2+ concentrations appear to be in the region of 0·05 mol m-3 adjacent to the guard cells even though much higher concentrations (up to 4 mol m-3) may be delivered to the leaf in the xylem sap. Thus it is suggested that the gradient in apoplastic Ca2+ may be very large over short distances, and may be strictly controlled by cells within the epidermis