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A molecular code for splicing silencing: configurations of guanosine-rich motifs.

Alternative pre-mRNA splicing is frequently used to expand the protein-coding capacity of genomes, and to regulate gene expression at the post-transcriptional level. It is a significant challenge to decipher the molecular language of tissue-specific splicing because the inherent flexibility of these mechanisms is specified by numerous short sequence motifs distributed in introns and exons. In the present study, we employ the glutamate NMDA (N-methyl-D-aspartate) R1 receptor (GRIN1) transcript as a model system to identify the molecular determinants for a brain region-specific exon silencing mechanism. We identify a set of guanosine-rich motifs that function co-operatively to regulate the CI cassette exon in a manner consistent with its in vivo splicing pattern. Whereas hnRNP (heterogeneous nuclear ribonucleoprotein) A1 mediates silencing of the CI cassette exon in conjunction with the guanosine-rich motifs, hnRNP H functions as an antagonist to silencing. Genome-wide analysis shows that, while this motif pattern is rarely present in human and mouse exons, those exons for which the pattern is conserved are generally found to be skipped exons. The identification of a similar arrangement of guanosine-rich motifs in transcripts of the hnRNP H family of splicing factors has implications for their co-ordinate regulation at the level of splicing.

Alternative Splicing↗

A seqlet-based maximum entropy Markov approach for protein secondary structure prediction.

A novel method for predicting the secondary structures of proteins from amino acid sequence has been presented. The protein secondary structure seqlets that are analogous to the words in natural language have been extracted. These seqlets will capture the relationship between amino acid sequence and the secondary structures of proteins and further form the protein secondary structure dictionary. To be elaborate, the dictionary is organism-specific. Protein secondary structure prediction is formulated as an integrated word segmentation and part of speech tagging problem. The word-lattice is used to represent the results of the word segmentation and the maximum entropy model is used to calculate the probability of a seqlet tagged as a certain secondary structure type. The method is markovian in the seqlets, permitting efficient exact calculation of the posterior probability distribution over all possible word segmentations and their tags by viterbi algorithm. The optimal segmentations and their tags are computed as the results of protein secondary structure prediction. The method is applied to predict the secondary structures of proteins of four organisms respectively and compared with the PHD method. The results show that the performance of this method is higher than that of PHD by about 3.9% Q3 accuracy and 4.6% SOV accuracy. Combining with the local similarity protein sequences that are obtained by BLAST can give better prediction. The method is also tested on the 50 CASP5 target proteins with Q3 accuracy 78.9% and SOV accuracy 77.1%. A web server for protein secondary structure prediction has been constructed which is available at http://www.insun.hit.edu.cn:81/demos/biology/index.html.

Algorithms↗

Origin of the Koreans: a population genetic study.

A population genetic study was undertaken to investigate the origin of Koreans. Thirteen polymorphic and 7 monomorphic blood genetic markers (serum proteins and red cell enzymes) were studied in a group of 437 Koreans. Genetic distance analyses by both cluster and principal components models were performed between Koreans and eight other populations (Koreans in China, Japanese, Han Chinese, Mongolians, Zhuangs, Malays, Javanese, and Soviet Asians) on the basis of 47 alleles controlled by 15 polymorphic loci. A more detailed analysis using 65 alleles at 19 polymorphic loci was performed on six populations. Both analyses demonstrated genetic evidence of the origin of Koreans from the central Asian Mongolians. Further, the Koreans are more closely related to the Japanese and quite distant from the Chinese. The above evidence of the origin of Koreans fits well with the ethnohistoric account of the origin of Koreans and the Korean language. The minority Koreans in China also maintained their genetic identity.

Alleles↗

Natural surfactant extract versus synthetic surfactant for neonatal respiratory distress syndrome.

BACKGROUND: This section is under preparation and will be included in the next issue. OBJECTIVES: To compare the effect of synthetic surfactant to natural surfactant in premature infants with established respiratory distress syndrome. SEARCH STRATEGY: Searches were made of the Oxford Database of Perinatal Trials, Medline (MeSH terms: pulmonary surfactant; limits: age groups, newborn infant; publication type, clinical trial), previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants, and journal hand searching in the English language. SELECTION CRITERIA: Randomized controlled trials comparing administration of synthetic surfactants to administration of natural surfactant extracts in premature infants with respiratory distress syndrome were considered for this review. DATA COLLECTION AND ANALYSIS: Data regarding clinical outcomes including pneumothorax, patent ductus arteriosus, necrotizing enterocolitis, intraventricular hemorrhage (all intraventricular hemorrhage and severe intraventricular hemorrhage), chronic lung disease, retinopathy of prematurity, and mortality were excerpted by the primary reviewer (R. Soll). Data analysis was conducted according to the standards of the Neonatal Cochrane Review Group. MAIN RESULTS: The meta-analysis supports a significant reduction in the risk of pneumothorax (typical relative risk 0.68, 95% CI 0.56, 0.83; typical risk difference -0.04 95% CI -0.06, -0.02). No disadvantages to natural surfactant extract treatment are noted regarding other outcomes. A trend towards reduced mortality is noted in association with natural surfactant extract treatment. REVIEWER'S CONCLUSIONS: Both natural surfactant extracts and synthetic surfactant extracts are effective in the treatment of established respiratory distress syndrome. Comparative trials demonstrate greater early improvement in the requirement for ventilatory support and fewer pneumothoraces associated with natural surfactant extract treatment. On clinical grounds, natural surfactant extracts would seem to be the more desirable choice.

Biological Products↗

Glial fibrillary acidic protein in the cerebrospinal fluid of children with autism and other neuropsychiatric disorders.

The cerebrospinal fluid (CSF) of 47 children and adolescents with autism was analyzed for the contents of two astroglial proteins, the glial fibrillary acidic protein (GFA) and S 100. The results were contrasted with those obtained in similarly aged cases with other neuropsychiatric disorders (n = 25) and in normal children (n = 10). S-100 did not discriminate the groups from each other. However, GFA in autism and autistic-like conditions was at a level almost three times that in the normal group. The results could implicate gliosis and unspecific brain damage in autism. An alternative model would be increased synapse turnover regardless of underlying cause.

Adolescent↗

Altering substrate chain length specificity of an acylhomoserine lactone synthase in bacterial communication.

Quorum sensing mediated by specific signal compounds (autoinducers) allows bacteria to monitor their cell density and enables a synchronized regulation of target gene sets. The best studied group of autoinducers are the acylhomoserine lactones (AHSLs), which are central to the regulation of virulence in many plant and animal pathogens. Variation of the acyl side chain of the AHSLs underlies the observed species specificity of this communication system. Here we show that even different strains of the plant pathogen Erwinia carotovora employ different dialects of this language and demonstrate the molecular basis for the acyl chain length specificity of distinct AHSL synthases. Under physiological concentrations, only the cognate AHSL with the "right" acyl chain is recognized as a signal that will switch on virulence genes. Mutagenesis of the AHSL synthase gene expI(SCC1) identified the changes M127T and F69L as sufficient to effectively alter ExpI(SCC1) (an N-3-oxohexanoyl-l-homoserine lactone producer) substrate specificity to that of an N-3-oxooctanoyl-l-homoserine lactone producer. Our data identify critical residues that define the size of the substrate-binding pocket of the AHSL synthase and will help in understanding and manipulating this bacterial language.

Amino Acid Sequence↗

Protein molecular function prediction by Bayesian phylogenomics.

We present a statistical graphical model to infer specific molecular function for unannotated protein sequences using homology. Based on phylogenomic principles, SIFTER (Statistical Inference of Function Through Evolutionary Relationships) accurately predicts molecular function for members of a protein family given a reconciled phylogeny and available function annotations, even when the data are sparse or noisy. Our method produced specific and consistent molecular function predictions across 100 Pfam families in comparison to the Gene Ontology annotation database, BLAST, GOtcha, and Orthostrapper. We performed a more detailed exploration of functional predictions on the adenosine-5'-monophosphate/adenosine deaminase family and the lactate/malate dehydrogenase family, in the former case comparing the predictions against a gold standard set of published functional characterizations. Given function annotations for 3% of the proteins in the deaminase family, SIFTER achieves 96% accuracy in predicting molecular function for experimentally characterized proteins as reported in the literature. The accuracy of SIFTER on this dataset is a significant improvement over other currently available methods such as BLAST (75%), GeneQuiz (64%), GOtcha (89%), and Orthostrapper (11%). We also experimentally characterized the adenosine deaminase from Plasmodium falciparum, confirming SIFTER's prediction. The results illustrate the predictive power of exploiting a statistical model of function evolution in phylogenomic problems. A software implementation of SIFTER is available from the authors.

Adenosine Deaminase↗

A computer program for predicting protein antigenic determinants.

A computerized method for predicting the locations of protein antigenic determinants is presented, which requires only the amino acid sequence of a protein, and no other information. This procedure has been used to predict the major antigenic determinant of the hepatitis B surface antigen, as well as antigenic sites on a series of test proteins of known antigenic structure [Hopp & Woods (1981) Proc. natn. Acad. Sci. U.S.A. 78, 3824-3828.] The method is suitable for use in smaller personal computers, and is written in the BASIC language, in order to make it available to investigators with limited computer experience and/or resources. A means of locating multiple antigenic sites on a homologous series of proteins is demonstrated using the influenza hemagglutinin as an example.

Amino Acid Sequence↗

Theodor Bücher Lecture. Metabolomics, modelling and machine learning in systems biology - towards an understanding of the languages of cells. Delivered on 3 July 2005 at the 30th FEBS Congress and the 9th IUBMB conference in Budapest.

The newly emerging field of systems biology involves a judicious interplay between high-throughput 'wet' experimentation, computational modelling and technology development, coupled to the world of ideas and theory. This interplay involves iterative cycles, such that systems biology is not at all confined to hypothesis-dependent studies, with intelligent, principled, hypothesis-generating studies being of high importance and consequently very far from aimless fishing expeditions. I seek to illustrate each of these facets. Novel technology development in metabolomics can increase substantially the dynamic range and number of metabolites that one can detect, and these can be exploited as disease markers and in the consequent and principled generation of hypotheses that are consistent with the data and achieve this in a value-free manner. Much of classical biochemistry and signalling pathway analysis has concentrated on the analyses of changes in the concentrations of intermediates, with 'local' equations - such as that of Michaelis and Menten v=(Vmax x S)/(S+K m) - that describe individual steps being based solely on the instantaneous values of these concentrations. Recent work using single cells (that are not subject to the intellectually unsupportable averaging of the variable displayed by heterogeneous cells possessing nonlinear kinetics) has led to the recognition that some protein signalling pathways may encode their signals not (just) as concentrations (AM or amplitude-modulated in a radio analogy) but via changes in the dynamics of those concentrations (the signals are FM or frequency-modulated). This contributes in principle to a straightforward solution of the crosstalk problem, leads to a profound reassessment of how to understand the downstream effects of dynamic changes in the concentrations of elements in these pathways, and stresses the role of signal processing (and not merely the intermediates) in biological signalling. It is this signal processing that lies at the heart of understanding the languages of cells. The resolution of many of the modern and postgenomic problems of biochemistry requires the development of a myriad of new technologies (and maybe a new culture), and thus regular input from the physical sciences, engineering, mathematics and computer science. One solution, that we are adopting in the Manchester Interdisciplinary Biocentre (http://www.mib.ac.uk/) and the Manchester Centre for Integrative Systems Biology (http://www.mcisb.org/), is thus to colocate individuals with the necessary combinations of skills. Novel disciplines that require such an integrative approach continue to emerge. These include fields such as chemical genomics, synthetic biology, distributed computational environments for biological data and modelling, single cell diagnostics/bionanotechnology, and computational linguistics/text mining.

Artificial Intelligence↗

A meta-analysis of the effect of soy protein supplementation on serum lipids.

Hypercholesterolemia is a major modifiable risk factor for cardiovascular disease. Some, but not all, studies have shown that soy protein intake decreases total and low-density lipoprotein cholesterol and triglycerides and increases high-density lipoprotein cholesterol. The objective of this meta-analysis was to examine the effect of soy protein supplementation on serum lipid levels in adults. English language articles were retrieved by searching MEDLINE (1966 to February 2005) and the bibliographies of the retrieved articles. A total of 41 randomized controlled trials in which isolated soy protein supplementation was the only intervention and the net changes in serum lipids during intervention were reported. Information on study design, sample size, participant characteristics, intervention, follow-up duration, and treatment outcomes was independently abstracted using a standardized protocol. Using a random-effects model, data from each study were pooled and weighted by the inverse of their variance. Soy protein supplementation was associated with a significant reduction in mean serum total cholesterol (-5.26 mg/dl, 95% confidence interval [CI] -7.14 to -3.38), low-density lipoprotein cholesterol (-4.25 mg/dl, 95% CI -6.00 to -2.50), and triglycerides (-6.26 mg/dl, 95% CI -9.14 to -3.38) and a significant increase in high-density lipoprotein cholesterol (0.77 mg/dl, 95% CI 0.20 to 1.34). Meta-regression analyses showed a dose-response relation between soy protein and isoflavone supplementation and net changes in serum lipids. These results indicate that soy protein supplementation reduces serum lipids among adults with or without hypercholesterolemia. In conclusion, replacing foods high in saturated fat, trans-saturated fat, and cholesterol with soy protein may have a beneficial effect on coronary risk factors.

Adult↗

Origins of the Indo-Europeans: genetic evidence.

Two theories of the origins of the Indo-Europeans currently compete. M. Gimbutas believes that early Indo-Europeans entered southeastern Europe from the Pontic Steppes starting ca. 4500 B.C. and spread from there. C. Renfrew equates early Indo-Europeans with early farmers who entered southeastern Europe from Asia Minor ca. 7000 BC and spread through the continent. We tested genetic distance matrices for each of 25 systems in numerous Indo-European-speaking samples from Europe. To match each of these matrices, we created other distance matrices representing geography, language, time since origin of agriculture, Gimbutas' model, and Renfrew's model. The correlation between genetics and language is significant. Geography, when held constant, produces a markedly lower, yet still highly significant partial correlation between genetics and language, showing that more remains to be explained. However, none of the remaining three distances--time since origin of agriculture, Gimbutas' model, or Renfrew's model--reduces the partial correlation further. Thus, neither of the two theories appears able to explain the origin of the Indo-Europeans as gauged by the genetics-language correlation.

Blood Group Antigens↗

Effects of statins on nonlipid serum markers associated with cardiovascular disease: a systematic review.

BACKGROUND: Statins reduce cardiovascular events to a greater extent than can be explained by their effect on lipids. Several studies have attempted to elucidate mechanisms by which statins reduce cardiovascular risk. PURPOSE: To summarize the effects of statins on nonlipid serum markers and to correlate statins' effect on serum markers with lipid levels and cardiovascular outcomes. DATA SOURCES: MEDLINE (1980 to 2003) search limited to English-language articles. STUDY SELECTION: Studies reporting original data in at least 10 participants on the effect of statins on outcomes of interest, excluding studies of cerivastatin, drug combinations, and patients with organ transplants. DATA EXTRACTION: Study design, sample size, treatment, and outcome data extracted on the basis of preestablished criteria. When appropriate, meta-analysis was performed by using a random-effects model. DATA SYNTHESIS: All statins are effective at lowering C-reactive protein levels, and the effect is not dose-dependent. Studies do not demonstrate a correlation between statins' effects on C-reactive protein levels and on lipids or cardiovascular outcomes. Statins do not affect fibrinogen levels, and limited data suggest little effect on lipid oxidation, tissue plasminogen activator, or plasminogen activator inhibitor. Platelet aggregation data are inconclusive. CONCLUSIONS: Among nonlipid serum markers examined, only C-reactive protein levels are statistically significantly affected by statins. These findings suggest that statin-mediated anti-inflammatory effects may contribute to the ability of statins to reduce risk for cardiovascular disease. Overall, however, available data are insufficient to support recommendations for using nonlipid serum markers in decisions regarding statin therapy for individual patients.

Biomarkers↗

Carbon sequestration in Synechococcus Sp.: from molecular machines to hierarchical modeling.

The U.S. Department of Energy recently announced the first five grants for the Genomes to Life (GTL) Program. The goal of this program is to "achieve the most far-reaching of all biological goals: a fundamental, comprehensive, and systematic understanding of life." While more information about the program can be found at the GTL website (www.doegenomestolife.org), this paper provides an overview of one of the five GTL projects funded, "Carbon Sequestration in Synechococcus Sp.: From Molecular Machines to Hierarchical Modeling." This project is a combined experimental and computational effort emphasizing developing, prototyping, and applying new computational tools and methods to elucidate the biochemical mechanisms of the carbon sequestration of Synechococcus Sp., an abundant marine cyanobacteria known to play an important role in the global carbon cycle. Understanding, predicting, and perhaps manipulating carbon fixation in the oceans has long been a major focus of biological oceanography and has more recently been of interest to a broader audience of scientists and policy makers. It is clear that the oceanic sinks and sources of CO(2) are important terms in the global environmental response to anthropogenic atmospheric inputs of CO(2) and that oceanic microorganisms play a key role in this response. However, the relationship between this global phenomenon and the biochemical mechanisms of carbon fixation in these microorganisms is poorly understood. The project includes five subprojects: an experimental investigation, three computational biology efforts, and a fifth which deals with addressing computational infrastructure challenges of relevance to this project and the Genomes to Life program as a whole. Our experimental effort is designed to provide biology and data to drive the computational efforts and includes significant investment in developing new experimental methods for uncovering protein partners, characterizing protein complexes, identifying new binding domains. We will also develop and apply new data measurement and statistical methods for analyzing microarray experiments. Our computational efforts include coupling molecular simulation methods with knowledge discovery from diverse biological data sets for high-throughput discovery and characterization of protein-protein complexes and developing a set of novel capabilities for inference of regulatory pathways in microbial genomes across multiple sources of information through the integration of computational and experimental technologies. These capabilities will be applied to Synechococcus regulatory pathways to characterize their interaction map and identify component proteins in these pathways. We will also investigate methods for combining experimental and computational results with visualization and natural language tools to accelerate discovery of regulatory pathways. Furthermore, given that the ultimate goal of this effort is to develop a systems-level of understanding of how the Synechococcus genome affects carbon fixation at the global scale, we will develop and apply a set of tools for capturing the carbon fixation behavior of complex of Synechococcus at different levels of resolution. Finally, because the explosion of data being produced by high-throughput experiments requires data analysis and models which are more computationally complex, more heterogeneous, and require coupling to ever increasing amounts of experimentally obtained data in varying formats, we have also established a companion computational infrastructure to support this effort as well as the Genomes to Life program as a whole.

Algorithms↗

Hypoallergenic formulas: are they really hypoallergenic?

BACKGROUND: Central to the management of cow's milk allergy in infancy is the complete elimination of cow's milk protein from the infant's diet for a variable period of time. The principal part of this approach is to provide nutrition for the child by means of hypoallergenic feeding formulas. Although a number of formulas are indeed marketed as hypoallergenic, it is not known with certainty how hypoallergenic they really are. A variety of ways of testing for hypoallergenicity have been developed, including the use of in vivo and in vitro animal model systems, chemical analyses, and patient studies, which are the ultimate test. OBJECTIVE: The purpose of the present report was to review the various ways of testing sensitizing capacity of infant feeding formulas for the treatment of children with cow's milk allergy. DATA SOURCES: English language articles were selected from PubMed, as were selected abstracts that would have immediate, practical clinical implications. The review focuses on themes related to animal models, chemical analysis, and clinical testing and clinical studies of intolerance to hydrolysates. RESULTS: Sensitizing capacity can be tested first in animal models either by in vivo or in vitro techniques. Although the information gained is valuable for preliminary evaluation, such techniques are intrinsically artificial. Second chemical analyses indicate that absence of larger peptides greater than 1,500 Da provides a critical industrial cutoff point. Third clinical effectiveness in child patients is of paramount importance. CONCLUSIONS: The results of the present review demonstrate that extensively hydrolyzed formulas are usually effective, but recently intolerance to hydrolysates has been observed. However, use of amino acid-based formulas free of antigens is highly effective in such infants.

Allergens↗

Neurocognitive dysfunction in children with neurofibromatosis type 1.

The cognitive dysfunction associated with neurofibromatosis type 1 (NF1) is an intriguing aspect of this phenotypically heterogeneous genetic neurocutaneous disorder. A broad range of both nonverbal and verbal learning disabilities are evident in approximately 30% to 65% of children with NF1. Deficits in IQ, executive function, attention, and motor skills have also been documented. Current challenges lie in discovering the underlying multifactorial etiologies of the cognitive abnormalities found in NF1. Likely answers lie in neuroanatomic correlates as seen on neuroimaging as well as in molecular and genetic advances into the role of neurofibromin, the protein product of the NF1 gene. The development of NF1 animal models with learning and memory difficulties similar to those seen in humans demonstrates promising preliminary evidence that medical treatment of cognitive abnormalities may one day be possible.

Animals↗

Pharmacokinetics, biochemical mechanism and mutation accumulation: a comprehensive model of chemical carcinogenesis.

Chemical carcinogenesis is a process beginning with carcinogen absorption and ending with development of a malignant tumor. Individual elements of this process have been studied intensively but no comprehensive model has been developed. This report describes a comprehensive model which incorporates carcinogen pharmacokinetics, biochemical mechanism of action, and the resultant mutation of normal cells to malignancy. Model parameters correspond to specific physiological and biochemical structures and processes. The model was encoded in a simulation language and used to examined biochemical and cellular effects of exposure to an initiator and a promoter. With laboratory validation, the model should be useful for interpretation and design of studies on carcinogenic mechanisms and for risk assessment.

Carcinogens↗

Effect of periodontal treatment on serum C-reactive protein levels: a systematic review and meta-analysis.

BACKGROUND: Systemic inflammation is increasingly being recognized as a risk factor for adverse cardiovascular events. Evidence is accumulating that associates periodontal disease with a higher risk for atherosclerotic plaque formation. A positive association between circulating C-reactive protein (CRP) levels and periodontal disease may be responsible for these observations. We undertook a systematic review and conducted a meta-analysis of the available evidence to examine the effect of periodontal treatment on systemic CRP levels and to assess the quality of the available evidence. METHODS: We conducted a systematic search of the English-language literature on the effect of periodontal treatment on CRP levels, as assessed by high-sensitivity assays, at least 2 months after periodontal treatment. The search was conducted in MEDLINE between 1966 and July 2005 and the Cochrane Central Register of Controlled Trials. We performed a meta-analysis using the DerSimonian and Laird random-effects model. RESULTS: The literature search yielded 814 citations of which 10 met the inclusion criteria. The meta-analysis of the randomized controlled trials (RCTs) showed that the difference in serum CRP levels is not significantly different between the two arms. Similarly, results from the single-cohort studies showed that the difference on serum CRP levels was not significantly different before and after treatment. CONCLUSIONS: There is now a large body of evidence to indicate that systemic inflammation is present in patients with periodontal disease. Thus, information from RCTs and single-cohort studies does not support the hypothesis that periodontal treatment can reduce systemic CRP levels.

C-Reactive Protein↗

Automated alignment and pattern recognition of single-molecule force spectroscopy data.

Recently, direct measurements of forces stabilizing single proteins or individual receptor-ligand bonds became possible with ultra-sensitive force probe methods like the atomic force microscope (AFM). In force spectroscopy experiments using AFM, a single molecule or receptor-ligand pair is tethered between the tip of a micromachined cantilever and a supporting surface. While the molecule is stretched, forces are measured by the deflection of the cantilever and plotted against extension, yielding a force spectrum characteristic for each biomolecular system. In order to obtain statistically relevant results, several hundred to thousand single-molecule experiments have to be performed, each resulting in a unique force spectrum. We developed software and algorithms to analyse large numbers of force spectra. Our algorithms include the fitting polymer extension models to force peaks as well as the automatic alignment of spectra. The aligned spectra allowed recognition of patterns of peaks across different spectra. We demonstrate the capabilities of our software by analysing force spectra that were recorded by unfolding single transmembrane proteins such as bacteriorhodopsin and NhaA. Different unfolding pathways were detected by classifying peak patterns. Deviant spectra, e.g. those with no attachment or erratic peaks, can be easily identified. The software is based on the programming language C++, the GNU Scientific Library (GSL), the software WaveMetrics IGOR Pro and available open-source at http://bioinformatics.org/fskit/.

Algorithms↗