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Antithrombin histidine variants 1H NMR resonance assignments and functional properties.

Three variants of the 57.5 kDa human plasma proteinase inhibitor antithrombin, H1Q, H65C, and H120C, have been expressed in baby hamster kidney cells to permit assignment of the 1H NMR resonances from the three histidines and evaluation of the role of these histidines in heparin binding. The NMR assignments have enabled more definitive interpretation of previous NMR-based studies of human antithrombin to be made. Although resonances of all three histidines are perturbed by heparin binding, only histidine 120 plays a significant role in the heparin binding site. The perturbations of resonances from histidines 1 and 65 indicate proximity to the heparin binding site and consequent sensitivity to the presence of heparin.

Antithrombins↗

Genetic association studies of complex traits: design and analysis issues.

Most common diseases and many important quantitative traits are complex genetic traits, with multiple genetic and environmental variables contributing to the observed phenotype. Because of the multi-factorial nature of complex traits, each individual genetic variant generally has only a modest effect, and the interaction of genetic variants with each other or with environmental factors can potentially be quite important in determining the observed phenotype. It remains largely unknown what sort of genetic variants explain inherited variation in complex traits, but recent evidence suggests that common genetic variants will explain at least some of the inherited variation in susceptibility to common disease. Genetic association studies, in which the allele or genotype frequencies at markers are determined in affected individuals and compared with those of controls (either population- or family-based), may be an effective approach to detecting the effects of common variants with modest effects. With the explosion in single nucleotide polymorphism (SNP) discovery and genotyping technologies, large-scale association studies have become feasible, and small-scale association studies have become plentiful. We review the different types of association studies and discuss issues that are important to consider when performing and interpreting association studies of complex genetic traits. Heritable and accurately measured phenotypes, carefully matched large samples, well-chosen genetic markers, and adequate standards in genotyping, analysis, and interpretation are all integral parts of a high-quality association study.

Gene Frequency↗

Genetic heterogeneity of single disseminated tumour cells in minimal residual cancer.

BACKGROUND: Because cancer patients with small tumours often relapse despite local and systemic treatment, we investigated the genetic variation of the precursors of distant metastasis at the stage of minimal residual disease. Disseminated tumour cells can be detected by epithelial markers in mesenchymal tissues and represent targets for adjuvant therapies. METHODS: We screened 525 bone-marrow, blood, and lymph-node samples from 474 patients with breast, prostate, and gastrointestinal cancers for single disseminated cancer cells by immunocytochemistry with epithelial-specific markers. 71 (14%) of the samples contained two or more tumour cells whose genomic organisation we studied by single cell genomic hybridisation. In addition, we tested whether TP53 was mutated. Hierarchical clustering algorithms were used to determine the degree of clonal relatedness of sister cells that were isolated from individual patients. FINDINGS: Irrespective of cancer type, we saw an unexpectedly high genetic divergence in minimal residual cancer, particularly at the level of chromosomal imbalances. Although few disseminated cells harboured TP53 mutations at this stage of disease, we also saw microheterogeneity of the TP53 genotype. The genetic heterogeneity was strikingly reduced with the emergence of clinically evident metastasis. INTERPRETATION: Although the heterogeneity of primary tumours has long been known, we show here that early disseminated cancer cells are genomically very unstable as well. Selection of clonally expanding cells leading to metastasis seems to occur after dissemination has taken place. Therefore, adjuvant therapies are confronted with an extremely large reservoir of variant cells from which resistant tumour cells can be selected.

Bone Marrow↗

Estrogen induction of the cyclin D1 promoter: involvement of a cAMP response-like element.

Estrogens induce cell proliferation in target tissues by stimulating progression through the G(1) phase of the cell cycle. Induction of cyclin D1 expression is a critical feature of the mitogenic action of estrogen. We have determined a region between -96 and -29 in the cyclin D1 promoter that confers regulation by estrogens in the human mammary carcinoma cells MCF-7. This region encompasses a unique known transcription factor binding site with a sequence of a potential cAMP response element (CRE-D1). The induction is strictly hormone dependent and requires the DNA binding domain as well as both AF-1 and AF-2 domains of the estrogen receptor (ER) alpha. Destruction of the CRE-D1 motif caused complete loss of estrogen responsiveness. Both c-Jun and ATF-2 transactivated the cyclin D1 promoter in transient transfection experiments, and a clear additional increase was detected when ER was cotransfected with either c-Jun or with c-Jun and ATF-2 but not with ATF-2 alone. Furthermore, the expression of a dominant negative variant of c-Jun, TAM67, completely abolished the induction of the cyclin D1 promoter both in the absence and presence of ER. We show that ATF-2 homodimers and ATF-2/c-Jun heterodimers, but not c-Jun homodimers, were able to bind the CRE of the cyclin D1 promoter. To interpret these results, we propose a mechanism in which ATF-2/c-Jun heterodimers bind to the CRE-D1 element and mediate the activation of cyclin D1 promoter by the ER. This mechanism represents a pathway by which estrogens control the proliferation of target cells.

Activating Transcription Factor 2↗

When insight just won't come: the failure of visual cues in the nine-dot problem.

The nine-dot problem is a classic in the field of human problem solving. Cognitive accounts of the problem's difficulty have been criticized on the grounds that the experimental methods on which they rely for support involve a qualitative change to the task requirements of the problem. The three experiments reported here utilize visual and visual-procedural hints to examine the notion that its difficulty is rooted in a mismatch between problem shape and solution shape. Experiment 1 demonstrated that a perceptual cue to the shape of the solution in the form of shading gave rise to only minimal improvements in performance; an additional hint about the relevance of the shading gave rise to modest, but not statistically significant, improvements. Experiment 2 replicated these findings against an additional control condition in which a solely verbal hint to violate the perceptual boundary of the problem shape was given. Furthermore, when both the verbal and visual hints were provided, performance improved only slightly. Experiment 3 provided participants with experience in producing the shape of the correct solution in problem variants closely related to the nine-dot problem. Performance on the transfer task, the basic nine-dot problem, remained at floor, however. These data suggest that visual constraint relaxation is unlikely to be the sole process by which the insight required to find a solution is achieved. The results are interpreted in terms of a previously proposed computational model of performance.

Adolescent↗

Hyperlipidaemia associated with genetic variation in the apolipoprotein B gene.

Common variants at the apolipoprotein B gene locus are associated with hyperlipidaemia, but conflicting data have been presented in the literature concerning the size of the effects and which polymorphisms give the best signal in the different groups of individuals studied. In this review, we will present a critique on the use and interpretation of association studies, with respect to the recent apolipoprotein B DNA polymorphism studies. The impact of these common polymorphisms and rare mutations of apolipoprotein B, primarily the substitution of arginine by glutamine at residue 3500 (R3500Q) that causes familial defective apolipoprotein B100, will also be considered.

Amino Acid Sequence↗

Predicting functional constraints across evolutionary timescales with phylogeny-informed genomic language models.

Genomic language models (gLMs) have emerged as a powerful approach for learning genome-wide functional constraints directly from DNA sequences. However, standard gLMs adapted from natural language processing often require extremely large model sizes and computational resources, yet still fall short of classical evolutionary models in predictive tasks. Here, we introduce GPN-Star (Genomic Pretrained Network with Species Tree and Alignment Representation), a biologically grounded gLM featuring a phylogeny-aware architecture that leverages whole-genome alignments and species trees to model evolutionary relationships explicitly. Trained on alignments spanning vertebrate, mammalian, and primate evolutionary timescales, GPN-Star achieves state-of-the-art performance across a wide range of variant effect prediction tasks in both coding and non-coding regions of the human genome. Analyses across timescales reveal task-dependent advantages of modeling more recent versus deeper evolution. To demonstrate its potential to advance human genetics, we show that GPN-Star substantially outperforms prior methods in prioritizing pathogenic and fine-mapped GWAS variants; yields unprecedented enrichments of complex trait heritability; and improves power in rare variant association testing. Extending beyond humans, we train GPN-Star for five model organisms - Mus musculus, Gallus gallus, Drosophila melanogaster, Caenorhabditis elegans, and Arabidopsis thaliana - demonstrating the robustness and generalizability of the framework. Taken together, these results position GPN-Star as a scalable, powerful, and flexible new tool for genome interpretation, well suited to leverage the growing abundance of comparative genomics data.

Journal Article↗

Extraversion, neuroticism and strength of the nervous system.

The hypothesized identity of the dimensions of extraversion-introversion and strength of the nervous system was tested on four groups of nine subjects (neurotic extraverts, stable extraverts, neurotic introverts, stable introverts). Strength of the subjects' nervous system was estimated using the electroencephalographic (EEG) variant of extinction with reinforcement. Introverted subjects were found to have weak nervous systems, according to the EEG index, while extraverted subjects had strong nervous systems, thus confirming the hypothesis. It was also found that the dimension of strength of the nervous system was unrelated to differences in neuroticism. The results are interpreted as adding support to Eysenck's theory relating differences in extraversion-introversion to differences in cortical arousal.

Acoustic Stimulation↗

Psychological and social characteristics and precipitants of vomiting in children with cyclic vomiting syndrome.

A psychological etiology or predisposition for cyclic vomiting syndrome (CVS) has long been suspected. Much of the psychiatric literature to date has blamed patients or their families for the problem or focused on psychoanalytic interpretation to account for the syndrome. Thirty-two patients with CVS were compared with 64 age- and sex-matched controls. The patients had a higher incidence of psychological symptoms and migraine. On the Achenbach Child Behavior Checklist patients had higher internalizing, somatic complaints, and anxiety/depression scores. CVS is a migraine variant, with attacks usually precipitated by stress and intercurrent infections. The psychological characteristics of patients with CVS probably contribute to their vulnerability.

Adolescent↗

Methionine synthase polymorphism A2756G is associated with susceptibility for thromboembolic events and altered B vitamin/thiol metabolism.

BACKGROUND AND OBJECTIVES: Vitamin B12 dependent methionine synthase (MS) regulates de novo production of methionine from homocysteine (Hcy). Since moderate elevations in Hcy are considered vasculotoxic, we examined a common variant (A2756G-MS) of the gene coding for this enzyme as a risk for thromboembolism. DESIGN AND METHODS: We investigated A2756G-MS and folate/thiol status in 51 individuals who had experienced a thromboembolic event (TE) and 95 subjects being treated for non-thromboembolic (NTE) vascular problems. RESULTS: The prevalence of the mutant G allele was lower in TE subjects than in controls, indicating a protective role for this base substitution (OR 0.39; 95%CI 0.20-0.78; p=0.010). Consistent with an advantage conferred by this allele, heterozygotes had generally lower levels of Hcy and glutathione (GSH), and higher levels of B-vitamins than wildtypes. The OR for the wildtype having an increased risk for TE was 2.32 (95%CI 1.06-5.08). Additionally, as might be predicted, TE-wildtypes had elevated GSH levels compared to corresponding NTE-wildtypes (p=0.004) - a likely response to oxidative stress. NTE subjects showed a dramatic reduction in Hcy between wildtype and heterozygote (p=0.017), and again between recessive and heterozygote genotypes (p=0.002). The same pattern, although not significant, occurred in TE subjects. The similarity in Hcy between clinical groups for each genotype raises questions on the etiological role of Hcy in TE. The functional relationship between enzyme variant and its B12-cofactor may be of more interest, since the polymorphic site occurs near the B12-binding domain, and our results indicate wildtype-TE subjects have a much lower level of vitamin B12 than heterozygote-TE subjects (p=0.0019). This effect is attenuated in NTE subjects. INTERPRETATION AND CONCLUSIONS: . A2756G-MS may protect against a thromboembolic event. The role of Hcy remains unclear.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗

[Stochastic approach in biochemical research].

The logic foundations of the probabilistic style for thinking and its methodological significance in the modern science are given. Complex, joint, ambiguous systems are the object of biochemical investigations at all organization levels and therefore biochemists often cannot obtain unambiguous results. It is shown that such systems are subjects to the study with the use of propositions of the probability theory which considers "random" events as a result of many-channel determination and is aimed to transform knowledge of these events into events predicted with certain probability. This provides a more profound analysis of a sum of facts and specificity of their theoretical interpretation. It is proved expedient to apply the probabilistic approach to study intramolecular and intermolecular interaction of elements, to characterize enzymes and membranes, to investigate objects comparatively and chemotaxanomically. It is stated that comprehension of "random" as a manifestation of a part of a sum of the possible or one of its variants stimulates the theoretical generalization of facts, elucidation of regularities of functioning, adaptation, development and diversity of every living thing.

Biochemical Phenomena↗

A report of a rare chromosome 9 variant with an unusual G-banding pattern in the 9qh region.

We present a case of a Caucasian multigravida with advanced maternal age who showed evidence of an unusual heterochromatin banding pattern on chromosome 9 and a similar fetal karyotype on amniocentesis. Although unusual banding patterns of this region have been described earlier, we report a new, clinically insignificant pattern. This case illustrates the care needed in analysing the heterochromatin region for accurate clinical interpretation of chromosome 9 polymorphisms.

Adult↗

Susceptibility to testicular germ-cell tumours in a 129.MOLF-Chr 19 chromosome substitution strain.

The identification of genes that control susceptibility to testicular germ-cell tumours (TGCTs), the most common cancer affecting young men, has been difficult. In laboratory mice, TGCTs arise from primordial germ cells in only the 129 inbred strains, and susceptibility is under multigenic control. The spontaneously arising mutation Ter (ref. 5) on mouse chromosome 18 (Refs 6,7) increases TGCT frequency on a 129/Sv background. We originally used Ter in genetic crosses to identify loci that control tumorigenesis. A genome scan of tumour-bearing progeny from backcrosses between the 129/Sv-Ter/+ and MOLF/Ei strains provided modest evidence that MOLF-derived alleles on chromosome 19 enhance development of bilateral TGCTs (ref. 9). To obtain independent evidence for linkage to the MOLF chromosome, we made an autosomal chromosome substitution strain (CSS; or 'consomic strain') in which chromosome 19 of 129/Sv+/+ was replaced by its MOLF-derived homologue. The unusually high frequency of TGCTs in this CSS (even in the absence of the Ter mutation) provides evidence confirming the genome survey results, identifies linkage for a naturally occurring strain variant allele that confers susceptibility to TGCTs and illustrates the power of CSSs in complex trait analysis.

Alleles↗

Activation of the lac promoter and its variants. Synergistic effects of catabolite activator protein and supercoiling in vitro.

Escherichia coli lac promoter variants are shown to be subject to large synergistic transcriptional activation by catabolite activator protein (CRP) and DNA supercoiling in vitro. Activation was studied for the lac wild-type promoter, a promoter with a variant spacing (lac delta l) and two promoters with variant -10 regions (lac ps, lac UV5). The variant promoters respond to the simultaneous presence of CRP and supercoiling by exhibiting large multiplicative activation at the low to moderate superhelicities that are most pertinent in vivo. Although all four promoters can be activated by CRP, those made stronger by changing downstream promoter elements are less CRP-activated even though each contains an identical CRP binding site. When each of the variant promoters is made stronger by introducing DNA supercoils, the apparent CRP activation initially remains constant but eventually declines at higher superhelicities. Thus, strengthening the lac promoter through either DNA sequence changes or the introduction of high-level DNA supercoiling can lead to diminished potential for activation by CRP. These results are interpreted in terms of a role for CRP in providing extra stabilizing contacts for RNA polymerase binding that are necessary only when other stabilizing features of promoter structure are lacking.

Bacterial Proteins↗

Quantitative assessment of genomic similarity from restriction fragment patterns.

A quantitative algorithm for comparing restriction fragment patterns (RFPs) was developed and used to estimate the genomic similarity of 18 isolates of pseudorabies virus of known origin. Variants of this algorithm using either untransformed or square-root-transformed differences between fragment sizes were investigated with regard to their ability to classify RFPs. Multidimensional scaling was used to represent spatially the genomic relatedness among samples, with 3 dimensions producing the most meaningful results. The square-root transformation provided more interpretable dimensions. The first dimension differentiated samples geographically, separating North American from European isolates. The second and third dimensions differentiated isolates with specific gene deletions (gE and gG, respectively) from those not having these deletions. Clusters of isolates were identified that were related either by collection from the same geographic area during a specific time period, or by laboratory intervention to create vaccines. These methods offer increased precision in the determination of genetic relatedness based on RFPs, and thus offer increased diagnostic accuracy for the determination of sources of infection.

Algorithms↗

Bizarre blue nevus: a case report with deoxyribonucleic acid content analysis.

A case report of an unusual variant of blue nevus is presented. The lesion demonstrated striking cytologic atypia but lacked clinical and certain histologic features of malignancy. Similarities and differences between this lesion and atypical blue nevus and Spitz nevus are discussed. An analysis of the deoxyribonucleic acid levels in lesional cells was consistent with polyploidy. This supports the interpretation of the lesion as atypical but is not inconsistent with a benign diagnosis.

Adult↗

Predicting genome-wide functional constraints with GPN-Star.

Genomic language models have emerged as a powerful approach for learning genome-wide functional constraints directly from DNA sequences1. However, standard genomic language models adapted from natural language processing often require large model sizes and computational resources, yet still fall short of classical evolutionary models in predictive tasks2-4. Here we introduce a genomic pretrained network with species tree and alignment representations (GPN-Star), which is a biologically grounded genomic language model featuring a phylogeny-aware architecture that leverages whole-genome alignments and species trees to model evolutionary relationships explicitly. Trained on alignments spanning vertebrate, mammal and primate evolutionary timescales, GPN-Star achieves state-of-the-art performance across a wide range of variant effect prediction tasks in both coding and non-coding regions of the human genome. Analyses across timescales show task-dependent advantages of modelling more recent versus deeper evolution. To demonstrate its potential to advance human genetics, we show that GPN-Star substantially outperforms previous methods in prioritizing pathogenic and fine-mapped genome-wide association study variants, yields strong enrichments of complex trait heritability and improves power in rare variant association testing5. Extending beyond humans, we train GPN-Star for five model organisms-Mus musculus, Gallus gallus, Drosophila melanogaster, Caenorhabditis elegans and Arabidopsis thaliana-demonstrating the robustness and generalizability of the framework. Taken together, these results position GPN-Star as a scalable, powerful and flexible tool for genome interpretation, well suited to leverage the growing abundance of comparative genomics data.

Journal Article↗

Tracer sedimentation equilibrium: a powerful tool for the quantitative characterization of macromolecular self- and hetero-associations in solution.

During the last two decades the measurement and analysis of sedimentation equilibrium has been used increasingly as a method for characterizing intermolecular interactions in solution. More recently, a variant of this technique has been developed, in which a trace amount of a single solute component is labelled so that the concentration gradient of that component at sedimentation equilibrium may be measured independently of the gradients of all other components. The dependence of equilibrium tracer gradients upon solution composition may be readily interpreted in the context of models for self- and hetero-association of the labelled component, and, in the case of concentrated solutions, repulsive as well as attractive solute-solute interactions. We present a summary of experimental and analytic methods, a brief review of some previously published applications, and a preview of new applications demonstrating capabilities beyond those afforded by other current techniques for characterizing macromolecular associations in solution.

Biophysics↗