The mTOR pathway is the central regulator of cell size1. External signals from growth factors and nutrients converge on the mTORC1 multi-protein complex to modulate downstream targets, but how the different inputs are integrated and translated into specific cellular responses is incompletely understood2–4. Deregulation of the mTOR pathway occurs in polycystic kidney disease (PKD)5–7, where cilia (filiform sensory organelles) fail to sense urine flow because of inherited mutations in ciliary proteins8. We therefore investigated if cilia have a role in mTOR regulation. Here, we show that ablation of cilia in transgenic mice results in enlarged cells when compared with control animals. In vitro analysis demonstrated that bending of the cilia by flow is required for mTOR downregulation and cell-size control. Surprisingly, regulation of cell size by cilia is independent of flow-induced calcium transients, or Akt. However, the tumour-suppressor protein Lkb1 localises in the cilium, and flow results in increased AMPK phosphorylation at the basal body. Conversely, knockdown of Lkb1 prevents normal cell-size regulation under flow conditions. Our results demonstrate that the cilium regulates mTOR signalling and cell size, and identify the cilium-basal body compartment as a spatially restricted activation site for Lkb1 signalling.

Copeptin is a novel, independent prognostic marker improving currently used risk stratification of stroke patients. Ann Neurol 2009;66:799-808.

No abstract

Bovine colostrum, the first milk that cows produce after parturition, contains high levels of growth factors and immunomodulatory components. Some healthy and diseased individuals may gain health benefits by consuming bovine colostrum as a food supplement. This review provides a systematic, critical evaluation of the current state of knowledge in this area. Fifty‐one eligible studies were identified from the following databases: Medline, Embase, Global Health, the Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature. Studies were heterogeneous with regard to populations, outcomes, and methodological quality, as judged by the Jadad assessment tool. Many studies used surrogate markers to study the effects of bovine colostrum. Studies suggesting clinical benefits of colostrum supplementation were generally of poor methodological quality, and results could not be confirmed by other investigators. Bovine colostrum may provide gastrointestinal and immunological benefits, but further studies are required before recommendations can be made for clinical application. Animal models may help researchers to better understand the mechanisms of bovine colostrum supplementation, the dosage regimens required to obtain clinical benefits, and the optimal methods for testing these effects in humans.

No abstract

Ataxia telangiectasia (AT) is a pleiotropic genetic disorder characterized by progressive neurodegeneration, especially of cerebellar Purkinje cells, immunodeficiency, increased incidence of cancer, and premature aging. The disease is caused by functional inactivation of the ATM (AT-mutated) gene product, which is thought to act as a sensor of reactive oxygen species and oxidative damage of cellular macromolecules and DNA. The compound phenotype of AT might thus be linked to a continuous state of oxidative stress leading to an increase of programmed cell death (apoptosis). To assess this hypothesis, we analyzed lipid peroxidation products and the oxidative stress associated DNA base damage 8-hydroxy-2-deoxyguanosine in patients with AT. Oxidative damage to lipids and DNA was found to be markedly increased in AT patients. These results indicate that ATM might play an important role in the maintenance of cell homeostasis in response to oxidative damage. In this context, a better control of levels of reactive oxygen species could be a rational foundation of therapeutic intervention to help alleviate some of the symptoms associated with AT.

1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) has been shown to modulate lymphocyte activation in vitro. Through binding to specific receptors 1,25-(OH)2 D3 inhibits proliferation, immunoglobulin production and the release of cytokines. Moreover, 1,25-(OH)2 D3 is efficiently produced by activated monocytes. These findings suggest that 1,25-(OH)2 D3 may play a role as a regulator of immunological activation. Consequently, we found it of interest to study the serum levels of the two major metabolites of vitamin D3 in patients with systemic lupus erythematosus (SLE) (n = 21), rheumatoid arthritis (RA) (n = 29) and osteoarthritis (n = 12). In patients with SLE the levels of 25-OH D3 were below those of the healthy controls (p = 0.0008) and OA (p = 0.0168). The levels 1,25-(OH)2 D3 corresponded to normal levels. There were no significant correlations between 25-OH D3 levels and clinical or paraclinical disease manifestations. Further, the phenotypic distribution of Gc-globulin, which binds vitamin D3 metabolites in circulation, was normal. The serum concentrations of 1,25-(OH)2 D3 and 25-OH D3 in patients with RA and OA corresponded to those of the controls. Although the cause of the reduced 25-OH D3 levels in SLE patients is unclear, possible beneficial effects of administration of vitamin D to these patients should be considered.

Bevacizumab is an anti-vascular endothelial growth factor (VEGF) antibody with activity against recurrent malignant glioma inducing high rates of objective responses as assessed by magnetic resonance imaging (MRI). However, the mechanisms of the anti-tumor action of bevacizumab are controversial. In particular, it is unclear whether and when bevacizumab induces hypoxia in gliomas. Vascular normalization with hyperperfusion and enhanced oxygen delivery to the tumor has been suggested as an alternative mechanism. We analyzed diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps in 18 consecutive patients with recurrent malignant glioma before and after exposure to bevacizumab. Stroke-like lesions with diffusion restriction on DWI and corresponding ADC decrease were induced by bevacizumab within the previously enhancing tumor area in 13 of 18 patients. These lesions were detectable as early as 4 weeks after initiation of therapy and were maintained for up to 80 weeks. In one patient, an ADC-decreased lesion was biopsied, and histology showed atypical necrosis and nuclear hypoxia-inducible factor 1alpha upregulation but no tumor recurrence. Normalized regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) were analyzed in selected patients. Both parameters were decreased in responders with diffusion-restricted lesions. Within the tumor bed, bevacizumab induces diffusion-restricted lesions in the presence of reduced rCBF and rCBV. The cause of these alterations is unclear but may involve atypical necrosis and chronic hypoxia.