A panel of cerebrospinal fluid potential biomarkers for the diagnosis of Alzheimer's disease

The diagnosis of Alzheimer's disease (AD), the most common form of dementia in the general population, usually relies upon the presence of typical clinical features and structural changes on brain magnetic resonance imaging. Over the last decade, a number of biological abnormalities have been reported in the cerebrospinal fluid (CSF) of AD patients, in particular altered levels of the tau protein and the 1-42 fragment of the amyloid precursor protein. These, however, have not yet proved sensitive and specific enough to be included in the diagnostic criteria for AD, leaving plenty of room for the search of novel biomarkers. The present study describes the analysis of CSF polypeptides by a protein-chip array technology called surface enhanced laser desorption/ionization-time of flight-mass spectrometry (SELDI-TOF-MS). Using this approach, we detected statistically significant quantitative differences (p < 0.05) regarding four overexpressed and one underexpressed polypeptides in the CSF of AD patients as compared to healthy controls. Four of them were further purified by strong anionic exchange chromatography (SAX) and identified by MS analysis as cystatin C, two beta-2-microglobulin isoforms, an unknown 7.7 kDa polypeptide, and a 4.8 kDa VGF polypeptide. The combination of the five polypeptides for the diagnosis of AD allowed to classified six AD patients out of the nine included in this study and all the ten controls, which means in this small cohort that the specificity and sensitivity are 100% and 66%, respectively. This study, based on the protein-chip array technology, demonstrates the presence in the CSF of novel potential biomarkers for AD, which may be used for the diagnosis and perhaps the assessment of the severity and progression of the disease.     

Cystatin C as a potential cerebrospinal fluid marker for the diagnosis of Creutzfeldt-Jakob disease

The definite diagnosis of Creutzfeldt-Jakob disease (CJD), the most common form of human prion diseases, relies upon neuropathological data usually obtained at autopsy. In living patients, the diagnosis, based on suggestive clinical features and EEG abnormalities, can be aided by the detection of altered levels of isoforms of the 14-3-3 protein in the cerebrospinal fluid (CSF). However, the validity of this test has been recently challenged and the search for other, more reliable biomarkers for CJD remains highly desirable. The present study describes the identification of a new potential surrogate marker in the CSF of CJD-affected patients. A preliminary study employing surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF) technology highlighted a protein at 13.4 kDa in a small group (n = 8) of CJD-affected patients. Further analysis aimed at identifying this protein using cationic exchange chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed it to be cystatin C. Additional immunoblot assays confirmed that the level of cystatin C was significantly increased (p 相似文献   

S1P1 localizes to the colonic vasculature in ulcerative colitis and maintains blood vessel integrity

Signaling through sphingosine-1-phosphate receptor₁ (S1P₁) promotes blood vessel barrier function. Degradation of S1P₁ results in increased vascular permeability in the lung and may explain side effects associated with administration of FTY720, a functional antagonist of the S1P₁ receptor that is currently used to treat multiple sclerosis. Ulcerative colitis (UC) is characterized by an increased density of abnormal vessels. The expression or role of S1P₁ in blood vessels in the colon has not been investigated. In the present study, we show that S1P₁ is overexpressed in the colonic mucosa of UC patients. This increase in S1P₁ levels reflects increased vascular density in the inflamed mucosa. Genetic deletion of S1pr1 in mice increases colonic vascular permeability under basal conditions and increases bleeding in experimental colitis. In contrast, neither FTY720 nor AUY954, two S1P receptor-targeting agents, increases bleeding in experimental colitis. Taken together, our findings demonstrate that S1P₁ is critical to maintaining colonic vascular integrity and may play a role in UC pathogenesis.     

Unexpected photobleaching of Alexa 488 in a fixed bacterial sample during 2-photon excitation

A sample of fixed bacterial cells was examined by immunofluorescence microscopy using an Alexa 488 conjugated secondary antibody for visualization. Excitation using visible light confirmed the expected photostability of this fluorophore; however, when using 2-photon excitation, Alexa 488 was rapidly and substantially photobleached. The unexpected instability of Alexa 488 under certain conditions may have deleterious consequences if not anticipated and accommodated in experimental protocols.