Determination of urinary retinol and creatinine as an early sensitive marker of renal dysfunction.

Determination of urinary retinol, which is a new promising early biomarker of renal damage typically expressed in the clinical environment as retinol/creatinine ratio, is currently difficult to accomplish. We have developed and validated the new ultra-high-performance liquid chromatography method with UV and mass spectrometry detection for the separation and quantification of retinol and creatinine in human urine in a single run. The separation of these two substances with completely different physicochemical properties was achieved using a column packed with fluorinated stationary phase and acetonitrile and aqueous ammonium formate buffer as the mobile phases. The separation was completed within 4 min. Our new method involves very fast and simple sample preparation requiring small amount of sample matrix and solvents. Deuterium labeled internal standard was used for the more precise quantification. The method was tested with real-life samples using urine collected from patients suffering from breast, colorectal, head, and neck cancer.

Extracellular adenosine mediates a systemic metabolic switch during immune response.

Immune defense is energetically costly, and thus an effective response requires metabolic adaptation of the organism to reallocate energy from storage, growth, and development towards the immune system. We employ the natural infection of Drosophila with a parasitoid wasp to study energy regulation during immune response. To combat the invasion, the host must produce specialized immune cells (lamellocytes) that destroy the parasitoid egg. We show that a significant portion of nutrients are allocated to differentiating lamellocytes when they would otherwise be used for development. This systemic metabolic switch is mediated by extracellular adenosine released from immune cells. The switch is crucial for an effective immune response. Preventing adenosine transport from immune cells or blocking adenosine receptor precludes the metabolic switch and the deceleration of development, dramatically reducing host resistance. Adenosine thus serves as a signal that the "selfish" immune cells send during infection to secure more energy at the expense of other tissues.

Casein kinase I epsilon somatic mutations found in breast cancer cause overgrowth in Drosophila.

We are using a candidate gene approach to identify genes contributing to cancer through somatic mutation. Somatic mutations were found in breast cancer samples in the human casein kinase I epsilon (CKIepsilon) gene, a homolog of the Drosophila gene dco in which certain point mutations lead to imaginal disc overgrowth. We therefore created fly genotypes in which the dco gene carried point mutations homologous to those discovered in CKIepsilon, and tested them in vivo. The results show that the most frequent mutation discovered in breast cancer, L39Q, causes a striking overgrowth phenotype in flies. Further experiments show that this mutation affects the newly recognized Fat/Warts signaling pathway, which controls organ size and shape in both flies and mammals. Another mutation, S101R, modifies the mutant phenotype so that the affected tissue disintegrates, mimicking more aggressive forms of breast cancer. Our results thus strongly support the conclusion that CKIepsilon mutations play important roles in breast carcinogenesis.