Methods in molecular biology
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Mass spectrometry-based quantitative proteomics can identify and quantify thousands of proteins in complex biological samples. Improved instrumentation, quantification strategies and data analysis tools now enable protein analysis on a genome-wide scale. ⋯ The spectrum of applications ranges from bacteria and eukaryotic cell culture systems to multicellular organisms. Here, we provide a step-by-step protocol on how to plan and perform large-scale quantitative proteome analysis using SILAC, from sample preparation to final data analysis.
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This chapter describes the main issues that genetic epidemiologists usually consider in the design of linkage and association studies. For linkage, we briefly consider the situation of rare, highly penetrant alleles showing a disease pattern consistent with Mendelian inheritance investigated through parametric methods in large pedigrees or with autozygosity mapping in inbred families, and we then turn our focus to the most common design, affected sibling pairs, of more relevance for common, complex diseases. Theoretical and more practical power and sample size calculations are provided as a function of the strength of the genetic effect being investigated. ⋯ The estimates of locus contribution to disease risk from genome-wide scans are often biased, and relying on them might result in an underpowered replication study. Population structure has so far caused less spurious associations than initially feared, thanks to systematic ethnicity matching and application of standard quality control measures. Differential bias could be a more serious threat and must be minimised by strictly controlling all the aspects of DNA acquisition, storage, and processing.
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Protocols for high-resolution respirometry (HRR) of intact cells, permeabilized cells, and permeabilized muscle fibers offer sensitive diagnostic tests of integrated mitochondrial function using standard cell culture techniques and small needle biopsies of muscle. Multiple substrate-uncoupler-inhibitor titration (SUIT) protocols for analysis of oxidative phosphorylation improve our understanding of mitochondrial respiratory control and the pathophysiology of mitochondrial diseases. Respiratory states are defined in functional terms to account for the network of metabolic interactions in complex SUIT protocols with stepwise modulation of coupling and substrate control. ⋯ Substrate control with electron entry separately through Complex I (pyruvate + malate or glutamate + malate) or Complex II (succinate + rotenone) restricts ETS capacity and artificially enhances flux control upstream of the Q-cycle, providing diagnostic information on specific branches of the ETS. Oxygen levels are maintained above air saturation in protocols with permeabilized muscle fibers to avoid experimental oxygen limitation of respiration. Standardized two-point calibration of the polarographic oxygen sensor (static sensor calibration), calibration of the sensor response time (dynamic sensor calibration), and evaluation of instrumental background oxygen flux (systemic flux compensation) provide the unique experimental basis for high accuracy of quantitative results and quality control in HRR.
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Many genetic mutations result in the disruption of (alternative) splicing. Prime examples are the SMN1 and SMN2 genes: a silent mutation in SMN2 leads to the skipping of the constitutive exon 7 in the majority of SMN2 transcripts, while this exon is generally included in SMN1 transcripts. ⋯ There are proteins and drugs that can chance alternative splicing events, e.g. increase the inclusion of exon 7 in SMN2. This chapter describes mini-genes and methods that can be employed to screen for candidate proteins and drugs.
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Psychoneuroimmunology (PNI) may provide the scientific basis for personalized and systems medicine. The exploration of the extensive interactions among psychological and behavioral factors, the nervous system, the immune system, and the endocrine system may help understand the mechanisms underlying health, wellness, and diseases. PNI theories based on systems biology methodologies may contribute to the identification of patient patterns for establishing psychological and physiological profiles for personalized medicine. ⋯ As inflammation is a critical connection among different diseases, the elucidation of the associations may contribute to the findings of systemic therapeutic targets. With the understanding of the translational implications of PNI, integrative interventions in multiple dimensions can be applied to modulate stress responses and promote healthier behaviors. These interventions include combination drug therapies, diets, nutritional supplements, meditation, and other behavioral and mind-body strategies.