A test of the nature of cosmic acceleration using galaxy redshift distortions.

Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the equations of cosmic expansion, accounting for about 75 per cent of the total energy density in the Universe. The simplest option for this 'dark energy' corresponds to a 'cosmological constant', perhaps related to the quantum vacuum energy. Physically viable alternatives invoke either the presence of a scalar field with an evolving equation of state, or extensions of general relativity involving higher-order curvature terms or extra dimensions. Although they produce similar expansion rates, different models predict measurable differences in the growth rate of large-scale structure with cosmic time. A fingerprint of this growth is provided by coherent galaxy motions, which introduce a radial anisotropy in the clustering pattern reconstructed by galaxy redshift surveys. Here we report a measurement of this effect at a redshift of 0.8. Using a new survey of more than 10,000 faint galaxies, we measure the anisotropy parameter beta = 0.70 +/- 0.26, which corresponds to a growth rate of structure at that time of f = 0.91 +/- 0.36. This is consistent with the standard cosmological-constant model with low matter density and flat geometry, although the error bars are still too large to distinguish among alternative origins for the accelerated expansion. The correct origin could be determined with a further factor-of-ten increase in the sampled volume at similar redshift.

Treatment of psoriasis vulgaris with topical calcipotriol: is the clinical improvement of lesional skin related to a down-regulation of some cell adhesion molecules?

Calcipotriol is demonstrably efficacious for the treatment of psoriasis by virtue of its effects on the skin's immune system and on epidermal growth. We performed this study to emphasize the difference in the expression of certain cell adhesion molecules (CAMs) (ICAM-1, ELAM-1, LFA-1, VLA-3, VLA-6) in lesional and perilesional skin of 10 patients with psoriasis, before and after treatment with topical Calcipotriol. We took two biopsies of lesional and perilesional skin from each patient before and after treatment and then performed an immunohistochemical study to observe the expression of these CAMs, utilizing monoclonal antibodies against these adhesion molecules. We noticed reduced levels of infiltrating cells along with the expression of ICAM-1, LFA-1, ELAM-1 and of CAMs VLA-3, VLA-6 in basal and suprabasal keratinocytes. On the basis of these data we hypothesize that, besides epidermal keratinocytes, another target for Calcipotriol may be the skin's own immune system, suggesting that Calcipotriol can modify T lymphocyte activity (IL-1 dependent) through a down-regulation of CAMs.

Cystic lymphangioma of the spleen: US-CT-MRI correlation.

A case of a surgically confirmed cystic lymphangioma of the spleen is presented. Preoperative imaging consisted of US, contrast-enhanced CT and MRI, all showing a multiloculated lesion with small cystic cavities divided by thin septa, corresponding to dilated lymphatic spaces. Preoperative studies correlated well with the pathologic findings. Cystic lymphangioma of the spleen is a very rare condition and is usually solitary and asymptomatic. Large lymphangiomas may be an indication for splenectomy, since the risk of rupture is high even from minor abdominal trauma. Preoperative diagnosis may be achieved with correlated noninvasive imaging.