1.
Johannsson, Gudmundur, 1960, et al.
(författare)
Improving glucocorticoid replacement therapy using a novel modified-release hydrocortisone tablet: a pharmacokinetic study.
2009
Ingår i: European journal of endocrinology / European Federation of Endocrine Societies. - 1479-683X .- 0804-4643. ; 161:1, s. 119-30
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: Endogenous plasma cortisol levels have a well-defined circadian rhythm. The aim of this project is to develop a once daily oral dual-release formulation for cortisol replacement therapy that mimics the diurnal variation in the plasma cortisol profile. OBJECTIVE: To determine single-dose plasma pharmacokinetics and dose-proportionality of oral 5 and 20 mg dual-release hydrocortisone tablets in healthy volunteers. In addition, the effect of food intake was investigated for the 20 mg dose. DESIGN: A randomised, controlled, two-way cross-over, double-blind, phase I study of oral hydrocortisone (modified (dual) release; 5 and 20 mg) with an open food-interaction arm. METHODS: The single dose pharmacokinetic studies were performed with betamethasone suppression. The two first study days were blinded and randomised between morning administration of 5 and 20 mg tablet in a fasting state. The third day was open with a 20 mg tablet taken 30 min after a high-calorie, high-fat meal. The plasma samples were assayed using both a validated LC-MS/MS and an immunoassay. The plasma pharmacokinetic variables were calculated using non-compartmental data analysis. RESULTS: The time to reach a clinically significant plasma concentration of cortisol (>200 nmol/l) was within 20 min and a mean peak of 431 (s.d. 126) nmol/l was obtained within 50 min after administration of the 20 mg tablet. Plasma cortisol levels remained above 200 nmol/l for around 6 h thereafter and all plasma concentrations 18-24 h after intake were below 50 nmol/l. In the fed state the time to reach 200 nmol/l was delayed by 28 and 9 min based on LC-MS/MS and immunoassay, respectively. The 5 and 20 mg tablets produced an increase in plasma exposure of cortisol that was not fully dose proportional. CONCLUSION: The dual release hydrocortisone tablet with once-daily administration produced a diurnal plasma cortisol profile mimicking the physiological serum cortisol profile.
2.
Kultima, Kim, et al.
(författare)
Development and evaluation of normalization methods for label-free relative quantification of endogenous peptides
2009
Ingår i: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 8:10, s. 2285-2295
Tidskriftsartikel (refereegranskat) abstract
The performances of 10 different normalization methods on data of endogenous brain peptides produced with label-free nano-LC-MS were evaluated. Data sets originating from three different species (mouse, rat, and Japanese quail), each consisting of 35-45 individual LC-MS analyses, were used in the study. Each sample set contained both technical and biological replicates, and the LC-MS analyses were performed in a randomized block fashion. Peptides in all three data sets were found to display LC-MS analysis order-dependent bias. Global normalization methods will only to some extent correct this type of bias. Only the novel normalization procedure RegrRun (linear regression followed by analysis order normalization) corrected for this type of bias. The RegrRun procedure performed the best of the normalization methods tested and decreased the median S.D. by 43% on average compared with raw data. This method also produced the smallest fraction of peptides with interblock differences while producing the largest fraction of differentially expressed peaks between treatment groups in all three data sets. Linear regression normalization (Regr) performed second best and decreased median S.D. by 38% on average compared with raw data. All other examined methods reduced median S.D. by 20-30% on average compared with raw data.
3.
Madeira, Alexandra, et al.
(författare)
Coupling surface plasmon resonance to mass spectrometry to discover novel protein-protein interactions
2009
Ingår i: Nature Protocols. - : Springer Science and Business Media LLC. - 1754-2189 .- 1750-2799. ; 4:7, s. 1023-1037
Tidskriftsartikel (refereegranskat) abstract
The elucidation of protein-protein interaction networks is a crucial task in the postgenomic era. In this protocol, we describe our approach to discover protein-protein interactions using the surface plasmon resonance technique coupled to mass spectrometry ( MS). A peptide or a protein is immobilized on a sensor chip and then exposed to brain extracts injected through the surface of the chip by a microfluidic system. The interactions between the immobilized ligand and the extracts can be monitored in real time. Proteins interacting with the peptide/protein are recovered, trypsinated and identified using MS. The data obtained are searched against a sequence database using the Mascot 2.1 software. Control experiments using blank sensor chips and/or randomized peptides are carried out to exclude nonspecific interactors. The protocol can be carried out in < 3 days. Other methods, such as yeast two-hybrid systems or pull-down approaches followed by MS, are widely used to screen protein-protein interactions. However, as the yeast two-hybrid system requires protein interactions in the nucleus of yeast, proteins that are abundant in other compartments may not be detected. Pull-down approaches based on immunoprecipitation can be used to study endogenous proteins but they require specific antibodies. The protocol presented here does not require the specific labeling or modification of proteins.
4.
Nilsson, Anna, et al.
(författare)
Striatal alterations of secretogranin-1, somatostatin, prodynorphin and cholecystokinin peptides in an experimental mouse model of Parkinson’s disease
2009
Ingår i: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 8:5, s. 1094-1104
Tidskriftsartikel (refereegranskat) abstract
The principal causative pathology of Parkinson disease is the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta projecting to the striatum in the brain. The information regarding the expression of neuropeptides in parkinsonism is very limited. Here we have elucidated striatal neuropeptide mechanisms in experimental parkinsonism using the unilateral 6-hydroxydopamine model to degenerate dopamine neurons. A thoroughly controlled sample preparation technique together with a peptidomics approach and targeted neuropeptide sequence collections enabled sensitive detection, identification, and relative quantitation of a great number of endogenous neuropeptides. Previously not recognized alterations in neuropeptide levels were identified in the unilateral lesioned mice with or without subchronic 3,4-dihydroxy-L-phenylalanine administration, the conventional treatment of Parkinson disease. Several of these peptides originated from the same precursor such as secretogranin-1, somatostatin, prodynorphin, and cholecystokinin. Disease-related biotransformation of precursors into individual peptides was observed in the experimental model of Parkinson disease. Several previously unreported potentially biologically active peptides were also identified from the striatal samples. This study provides further evidence that neuropeptides take part in mediating the central nervous system failure associated with Parkinson disease.
