Thr92Ala polymorphism in the type 2 deiodinase gene: an evolutionary perspective

PURPOSE

In the past, a role of thyroid hormones in human evolution has been hypothesized. T3, the metabolically active form, derives from extrathyroidal conversion of T4 by deionidase 2 (D2) enzyme encoded by DIO2 gene. In thyroid-deficient patients, decreased levels of free T3 have been associated with the polymorphism rs225014 A/G in DIO2, which causes the substitution of Threonine with Alanine (p.Thr92Ala) at protein level.

METHODS

We compared DNA and protein sequences of D2 from archaic human subspecies with those of contemporary humans.

RESULTS

Neanderthals and Denisovans displayed only the G allele at the rs225014 polymorphism, which encodes for an Alanine on the amino acid level. These data suggest that these hominines were homozygous for the Ala amino acid. These arcaic humans often lived in condition of iodine deficiency and thus, defective mechanisms of T3 biosynthesis could be life threatining. A reduced D2 activity is likely to cause decreased T3 levels, which could be critical for those individuals. Neanderthals and Denisovans were hunters/gatherers, and their diet was mainly based on the consumption of meat, with a low intake of carbohydrates. The need for circulating T3 is reduced at such alimentary conditions. On the basis of our genome comparisons the A allele, corresponding to Threonine and associated with higher levels of circulating T3 in thyroid-deficient patients, appeared for the first time during evolution in Anatomically Modern Humans during the Upper Pleistocene and has been conserved during the Neolithic age. With the advent of agriculture and herding, individuals carrying A allele might have a higher probability for surviving and reproducing. Thus, the variant was positively selected during the evolution.

CONCLUSION

Here we present an evolutionary perspective for p.Thr92Ala variant of D2 from Neanderthals to Anatomically Modern Humans.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Myocardial Perfusion and Metabolism After Transcoronary Ablation of Septum Hypertrophy (TASH) in Hypertrophic Obstructive Cardiomyopathy

Outflow obstruction constitutes a major problem in hypertrophic obstructive cardiomyopathy (HOCM) and may be treated by transcoronary injection of ethanol into septal arteries (transcoronary ablation of septum hypertrophy, TASH). We report on myocardial perfusion and glucose metabolism in a 50 year old man in whom TASH led to a reduction of septal thickness (9 vs. 26 mm), a sustained elimination of the outflow tract obstruction (resting gradient 0 vs. 60 mmHg; postES-gradient 10 vs. 145 mmHg) and a substantial clinical improvement (NYHA stage II vs. Il-lll) without impairment of global ventricular function (left ventricular ejection fraction 0.62 vs. 0.64). After TASH, perfusion and glucose metabolism were assessed by positron emission tomography (PET) using F-18-fluorodeoxyglucose (F-18-FDG) and Tc-99m-MIBI single photon emission tomography (SPECT). TASH results in matched reduction of perfusion and glucose consumption in a circumscribed area fed by the septal branch used for ethanol injection. No remote effects were observed. TASH leads to a sharply delineated septal reduction of perfusion and metabolism with consecutive reduction of septal thickness, a sustained elimination of the outflow tract obstruction, and a substantial clinical improvement without impairment of global ventricular function.

An earring for the double helix: assembly of topological links comprising duplex DNA and a circular oligodeoxynucleotide

Abstract Novel DNA nanostructures, locked pseudorotaxane and locked catenane were assembled through topological linkage of a double-stranded target to a circular oligodeoxyribonucleotide (cODN)(+). The formation of these supramolecular complexes occurs with remarkable sequence specificity and is accomplished via local opening of duplex DNA by a pair of homopyrimidine bis-PNAs. The obtained cODN label, resembling an earring, forms a true topological link with the linear or closed circular (cc) target DNA and occupies a fixed position along the double helix. The PNA directed assembly described here introduces PNA oligomers into the repertoire of DNA nanotechnological tools.

Strahlungsloser Übergang von Elektronenanregungsenergie durch dünne Schichten

Es wird eine monomolekulare Schicht eines Farbstoffs S (Sensibilisator) erzeugt. Darüber bringt man eine Bariumstearatschicht der Dicke d durch Aufeinanderlagern mehrerer monomolekularer Schichten. Auf dieser Schicht wird eine monomolekulare Schicht eines Farbstoffs A (Akzeptor), dessen Absorptionsmaximum im Bereich der Fluoreszenzbande von S liegt, erzeugt. Wird im Absorptionsbereich von S angeregt, so beobachtet man, falls d ≧ 250 A ist, eine deutliche Fluoreszenz von S. Ist d ≦ 100 Ā, so ist die Fluoreszenz gelöscht. Es findet in diesem Fall ein strahlungsloser Energieübergang von S nach A statt. Bei dem hier gegebenen Verfahren hat man im Gegensatz zu bisherigen Verfahren zum Nachweis des strahlungslosen Energieübergangs nicht mit Störungen durch Trivialeffekte (Sekundärabsorption des Fluoreszenzlichts von S durch A, Energieübertragung durch Zusammenstoß von S und A, Vorhandensein von Assoziaten von S und A) zu rechnen.

Ringstrom bei cyclischen Polyenen mit alternierenden und ausgeglichenen Bindungsabständen

The ring current effect in NMR has generally been used to distinguish between equal and alternant bonds in cyclic π-electron systems, assuming a strong ring current in equal-bonds-hydrocarbons and no ring current in alternant-bonds-hydrocarbons. A calculation of the ring current is presented based on the one dimensional electron gas model. The effect of bond alternation is considered by a sine curve potential.

Proceeding from a model with equal bonds to a model with alternant bonds the ring current is strongly reduced in rings with more than 10 members; it is reduced by 24% and 51% only in 6 and 10 membered rings, respectively. In non-HücKEL type rings with 4 to 16 carbon atoms the ring current is directed opposite to the classical current and is strongest in cyclobutadiene. The contribution of the π-electrons to the susceptibility of these compounds is therefore paramagnetic and ring current shifts opposite to those in HÜCKEL rings are to be expected. These results are confirmed by the proton chemical shifts in the NMR spectrum of [16]-Annulene.

Analogiebetrachtungen und Analogrechner zur Behandlung der Korrelation von Π-Elektronen (1)

Um das Verhalten eines Moleküls bei Lichteinwirkung zu behandeln, wird die Annahme zugrunde gelegt, daß jedes π-Elektron im Feld der Lichtwelle, im Feld des Molekülrumpfs und im zeitlich veränderlichen gemittelten Feld aller übrigen π-Elektronen des Moleküls steht. Das sich so mit der zeitabhängigen SCHRÖDINGER-Gleichung ergebende Gleichungssystem ist analog zu dem System der Gleichungen, die das Verhalten einer Gesamtheit untereinander gekoppelter linearer klassischer Oszillatoren beschreibt, welche unter der Wirkung einer periodisch veränderlichen äußeren Kraft stehen. Das Gleichungssystem kann mit einem geeigneten Analogrechner leicht gelöst werden und das Verfahren ist daher auch im Fall komplizierter π-Elektronensysteme leicht durchführbar. Es zeigt sich, daß das Verfahren zu einer Näherung führt, wie sie in der Methode der Konfigurationswechselwirkung bei Mitberücksichtigung der zweifach angeregten Konfigurationen erreicht wird. Der Einfluß des Lösungsmittels auf die Größe des an den Elektronen wirksamen Feldes der Lichtwelle wird untersucht.

Über eine Erweiterung der ω-Methode

Electron repulsion and spin properties of π-electrons are explicitely considered in Pople's SCF-theory; in the ω-method electron interaction is included in a simple way, but there is no physical justification for this procedure. In this paper we describe an LCAO-method (ωrs-method), in which π-electron repulsion is explicitely included and spin properties are neglected. Bond lengths, dipole moments, ionisation energies are calculated, and an explanation of the Scheibe phenomenon is given.

The Self-Assembly of an Amphiphilic Block Copolymer: A Dissipative Particle Dynamics Study

The self-assembly of a poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) blockcopolymer (EO13PO30EO13) in the presence of water was investigated. The phases have been studied with the mesoscopic simulation technique Dissipative Particle Dynamics (DPD). The micellar, hexagonal, lamellar, bicontinuous and inverse micellar phase have been identified with this method and showed remarkable agreement with the experimental phase behavior. This work showed that the Dissipative Particle Dynamics simulations are also suitable for complicated polymer systems such as the EO13PO30EO13 triblock copolymer.

Mesoscale Computer Simulations on the Phase Behavior of the Non-Ionic Surfactant C12E5

Dissipative Particle Dynamics is a mesoscopic simulation method which allows to predict the self-assembly of amphiphilic polymers and surfactants. It was possible to reproduce the phase behavior of the non-ionic surfactant C12E5 in water. The three different phases L1, La and L2 could be characterized with Dissipative Particle Dynamics.

Structural basis for pH-dependent alterations of reaction specificity of vertebrate lipoxygenase isoforms

Lipoxygenases have been classified according to their specificity of fatty acid oxygenation and for several plant enzymes pH-dependent alterations in the product patterns have been reported. Assuming that the biological role of mammalian lipoxygenases is based on the formation of specific reaction products, pH-dependent alterations would impact enzymes' functionality. In this study we systematically investigated the pH-dependence of vertebrate lipoxygenases and observed a remarkable stability of the product pattern in the near physiological range for the wild-type enzyme species. Site-directed mutagenesis of selected amino acids and alterations in the substrate concentrations induced a more pronounced pH-dependence of the reaction specificity. For instance, for the V603H mutant of the human 15-lipoxygenase-2 8-lipoxygenation was dominant at acidic pH (65%) whereas 15-H(p)ETE was the major oxygenation product at pH 8. Similarly, the product pattern of the wild-type mouse 8-lipoxygenase was hardly altered in the near physiological pH range but H604F exchange induced strong pH-dependent alterations in the positional specificity. Taken together, our data suggest that the reaction specificities of wild-type vertebrate lipoxygenase isoforms are largely resistant towards pH alterations. However, we found that changes in the assay conditions (low substrate concentration) and introduction/removal of a critical histidine at the active site impact the pH-dependence of reaction specificity for some lipoxygenase isoforms.