Triploidy—Observations in 154 Diandric Cases

Hydatidiform moles (HMs) are abnormal human pregnancies with vesicular chorionic villi, imposing two clinical challenges; miscarriage and a risk of gestational trophoblastic neoplasia (GTN). The parental type of most HMs are either diandric diploid (PP) or diandric triploid (PPM). We consecutively collected 154 triploid or near-triploid samples from conceptuses with vesicular chorionic villi. We used analysis of DNA markers and/or methylation sensitive-MLPA and collected data from registries and patients records. We performed whole genome SNP analysis of one case of twinning (PP+PM).In all 154 triploids or near-triploids we found two different paternal contributions to the genome (P1P2M). The ratios between the sex chromosomal constitutions XXX, XXY, and XYY were 5.7: 6.9: 1.0. No cases of GTN were observed. Our results corroborate that all triploid human conceptuses with vesicular chorionic villi have the parental type P1P2M. The sex chromosomal ratios suggest approximately equal frequencies of meiosis I and meiosis II errors with selection against the XYY conceptuses or a combination of dispermy, non-disjunction in meiosis I and meiosis II and selection against XYY conceptuses. Although single cases of GTN after a triploid HM have been reported, the results of this study combined with data from previous prospective studies estimate the risk of GTN after a triploid mole to 0% (95% CI: 0–1,4%).     

G-quadruplexes are specifically recognized and distinguished by selected designed ankyrin repeat proteins

We introduce designed ankyrin repeat binding proteins (DARPins) as a novel class of highly specific and structure-selective DNA-binding proteins, which can be functionally expressed within all cells. Human telomere quadruplex was used as target to select specific binders with ribosome display. The selected DARPins discriminate the human telomere quadruplex against the telomeric duplex and other quadruplexes. Affinities of the selected binders range from 3 to 100 nM. CD studies confirm that the quadruplex fold is maintained upon binding. The DARPins show different specificity profiles: some discriminate human telomere quadruplexes from other quadruplex-forming sequences like ILPR, c-MYC and c-KIT, while others recognize two of the sequences tested or even all quadruplexes. None of them recognizes dsDNA. Quadruplex-binding DARPins constitute valuable tools for specific detection at very small scales and for the in vivo investigation of quadruplex DNA.     

The substitution of arginine for glycine 85 of the alpha 1(I) procollagen chain results in mild osteogenesis imperfecta. The mutation provides direct evidence for three discrete domains of cooperative melting of intact type I collagen.

We report a case of mild osteogenesis imperfecta in a 56-year-old male undergoing aortic valve replacement surgery. The primary defect in this patient was the substitution of arginine for glycine 85 in one of the two chains of alpha 1(I) procollagen. The thermal stability of the type I collagen synthesized by the patient's cultured skin fibroblasts was examined by enzymatic digestion. Digestion of the mutant type I collagen with trypsin and chymotrypsin at increasing temperatures sequentially generated three discrete collagenous fragments, approximately 90, 170, and 230 amino acids shorter than normal type I collagen. This incremental thermal denaturation is indicative of cooperative melting blocks within the type I collagen. This is the first demonstration of such cooperative blocks of melting in intact, essentially normal post-translationally modified type I collagen. This direct evidence for cooperative melting domains of uncut type I collagen suggests that discrete blocks of amino acids function as core sites stabilizing the collagen helix. The location of mutations of the alpha chains of type I collagen relative to these discrete blocks of amino acids may influence the severity of the disease phenotype.     

Selection of the conodont Idiognathodus simulator (Ellison) as the event marker for the base of the global Gzhelian Stage (Upper Pennsylvanian, Carboniferous)

Studies carried out for more than 10 years by the Task Group to establish GSSPs at the base of the Moscovian–Kasimovian and Kasimovian–Gzhelian boundaries have resulted in the proposal that the level at which the conodont species Idiognathodus simulator (Ellison, 1941) first appears be selected to mark the base of the Gzhelian Stage. This expands this eastern European chronostratigraphic unit to a global scale.I. simulator (sensu Barrick et al., 2008) has been identified so far in Midcontinent and eastern North America, the Moscow and Donets basins and southern Urals of eastern Europe, and in south-central China. Correlation of this level based on this species and other conodont species can be reinforced in some areas by ammonoid and fusulinid data.     

Suppression of Electron Transfer to Dioxygen by Charge Transfer and Electron Transfer Complexes in the FAD-dependent Reductase Component of Toluene Dioxygenase

The three-component toluene dioxygenase system consists of an FAD-containing reductase, a Rieske-type [2Fe-2S] ferredoxin, and a Rieske-type dioxygenase. The task of the FAD-containing reductase is to shuttle electrons from NADH to the ferredoxin, a reaction the enzyme has to catalyze in the presence of dioxygen. We investigated the kinetics of the reductase in the reductive and oxidative half-reaction and detected a stable charge transfer complex between the reduced reductase and NAD⁺ at the end of the reductive half-reaction, which is substantially less reactive toward dioxygen than the reduced reductase in the absence of NAD⁺. A plausible reason for the low reactivity toward dioxygen is revealed by the crystal structure of the complex between NAD⁺ and reduced reductase, which shows that the nicotinamide ring and the protein matrix shield the reactive C4a position of the isoalloxazine ring and force the tricycle into an atypical planar conformation, both factors disfavoring the reaction of the reduced flavin with dioxygen. A rapid electron transfer from the charge transfer complex to electron acceptors further reduces the risk of unwanted side reactions, and the crystal structure of a complex between the reductase and its cognate ferredoxin shows a short distance between the electron-donating and -accepting cofactors. Attraction between the two proteins is likely mediated by opposite charges at one large patch of the complex interface. The stability, specificity, and reactivity of the observed charge transfer and electron transfer complexes are thought to prevent the reaction of reductase_TOL with dioxygen and thus present a solution toward conflicting requirements.     

Advantages of arthroscopy of the knee joint]

Arthroscopic surgery causes considerably less soft tissue damage than conventional surgery. As the result of the development of an optical system employed with a chip camera and a video chain arthroscopic knee surgery can be ideally documented with excellent picture quality. Besides the advantage of soft-tissue sparing procedures, diagnosis is substantially improved and operative procedures can be kept to a minimum. This means, in particular in the case of meniscus procedures, that only the damaged areas are removed, this minimising changes to the biomechanics of the knee. The technical equipment, the arthroscopic surgery technic and the advantages of the knee arthroscopy are discussed.     

Neuronal mechanisms contributing to long-term sensitization in Aplysia

1.) Cellular processes that contribute to the acquisition and expression of long-term sensitization have been examined in Aplysia. The tail-siphon withdrawal reflex was studied because the neural circuit for this reflex has been well characterized. Furthermore, the sensory neurons of this neural circuit exhibit cellular changes that accompany short-term sensitization. 2.) Repeated application of noxious stimuli to the animal produces a long-lasting enhancement of reflex withdrawal of the siphon when the animal is tested with a weak stimulus to the tail. These findings confirm the existence of long-term sensitization in Aplysia, first described by Pinkser et al. (1973). 3.) Biophysical correlates of long-term sensitization were examined in the first central relay of the tail-siphon reflex circuit, the sensory neurons that innervate the animal's tail. The net outward membrane currents of these cells reduced after 24 hours as a consequence of long-term sensitization training. 4.) The intracellular signal for the induction of these changes in membrane currents was examined by intracellular injection of cAMP into individual sensory neurons. This procedure mimics at least some of the effects of sensitization training at the single-cell level. cAMP induced a long-term reduction of membrane K+ currents 24 hours after the cells were injected with cAMP. The membrane currents reduced by cAMP were similar to those reduced by long-term sensitization training. 5.) Preliminary experiments indicate that neurotransmitters and agents that induce an evaluation of cAMP in the sensory neurons also alter the incorporation of labeled amino acids into specific proteins in the sensory neurons.(ABSTRACT TRUNCATED AT 250 WORDS)