Molecular Dynamics Simulations of the d(TAT) Triple Helix

Molecular dynamics (MD) simulations have been used to study the dynamical and time-averaged characteristics of the DNA triple helix d(T)10âd(A)10âd(T)10. The structures sampled during the trajectory resemble closely the B-type model for the DNA triplex proposed on the basis of NMR data, although there are some subtle differences. Alternative P- and A-type conformations for the triplex, suggested from X-ray experiments, are not predicted to contribute significantly to the structure of the DNA triplex in solution. Comparison with the best available experimental data supports the correctnes of the MD-generated structures. The analysis of the collected data gives a detailed picture of the characteristics of triple-helix DNA. A new and interesting pattern of hydration, specific for triplex DNA, is an important observation. The results suggest that molecular dynamics can be useful for the study of novel nucleic acid structures.

Decompression during Late Proterozoic Al2SiO5 Triple-Point Metamorphism at Cerro Colorado, New Mexico

An outstanding problem in understanding the late Proterozoic tectonic assembly of the southwest is identifying the tectonic setting associated with regional metamorphism at 1.4 Ga. Both isobaric heating and cooling, and counter-clockwise looping PT paths are proposed for this time. We present a study of the Proterozoic metamorphic and deformation history of the Cerro Colorado area, southern Tusas Mountains, New Mexico, which shows that the metamorphism in this area records near-isothermal decompression from 6 to 4 kbar at ca. 1.4 Ga. We do not see evidence for isobaric heating at this time. Decompression from peak pressures is recorded by the reaction Ms + Grt = St + Bt, with a negative slope in PT space; the reaction Ms + Grt = Sil + Bt, which is nearly horizontal in PT space; and partial to total pseudomorphing of kyanite by sillimanite during the main phase of deformation. The clearest reaction texture indicating decompression near peak metamorphic temperature is the replacement of garnet by clots of sillimanite, which are surrounded by halos of biotite. The sillimanite clots, most without relict garnet in the cores and with highly variable aspect ratios, are aligned. They define a lineation that formed with the dominant foliation. An inverted metamorphic gradient is locally defined by sillimanite-garnet schists (625 degrees C) structurally above staurolite-garnet schists (550 degrees C) and implies ductile thrusting during the main phase of deformation. The exhumation that led to the recorded decompression was likely in response to crustal thickening due to ductile thrusting and subsequent denudation.

Triple innominate osteotomy for Legg-Calvé-Perthes disease in children: does the lateral coverage change with time?

Triple innominate osteotomy (TIO) is one of the modalities of surgical containment in Legg-Calvé-Perthes disease (LCPD). However, overcoverage with TIO can lead to pincer impingement.

Dysphagia due to triple A syndrome: successful treatment of achalasia by balloon dilatation

Triple A syndrome is a rare autosomal recessive inherited disorder which is characterized by alacrima, adrenal insufficiency, and achalasia. We report on a 14-year old girl with dysphagia, regurgitation, and vomiting since 5 years. At the age of five years an Addison crisis was diagnosed and cortisone substitution was initiated. In addition, the patient had episodes of conjunctivitis. Severe esophagitis and candida infection were diagnosed by esophago-gastro-duodenoscopy and treated with omeprazole and fluconazole. The esophageal barium swallow was typical for achalasia. Medical treatment of achalasia with oral nifedipine resulted only in a partial and temporal improvement. But after seven balloon dilatations dysphagia and nocturnal coughing improved clearly and a remarkable gain of weight could be seen. Direct sequencing showed a homozygous nonsense mutation in exon 11 of the AAAS gene leading to truncation at position 342 of the 546 amino acid protein. CONCLUSION: Triple A syndrome has to be considered in patients with dysphagia. In our patient, the absence of tears since birth followed by adrenal insufficiency were early signs of the triple A syndrome. Balloon dilatation of the esophago-gastric junction is an effective treatment, which can avoid surgical interventions.

Heterosis for biomass-related traits in Arabidopsis investigated by quantitative trait loci analysis of the triple testcross design with recombinant inbred lines

Arabidopsis thaliana has emerged as a leading model species in plant genetics and functional genomics including research on the genetic causes of heterosis. We applied a triple testcross (TTC) design and a novel biometrical approach to identify and characterize quantitative trait loci (QTL) for heterosis of five biomass-related traits by (i) estimating the number, genomic positions, and genetic effects of heterotic QTL, (ii) characterizing their mode of gene action, and (iii) testing for presence of epistatic effects by a genomewide scan and marker x marker interactions. In total, 234 recombinant inbred lines (RILs) of Arabidopsis hybrid C24 x Col-0 were crossed to both parental lines and their F1 and analyzed with 110 single-nucleotide polymorphism (SNP) markers. QTL analyses were conducted using linear transformations Z1, Z2, and Z3 calculated from the adjusted entry means of TTC progenies. With Z1, we detected 12 QTL displaying augmented additive effects. With Z2, we mapped six QTL for augmented dominance effects. A one-dimensional genome scan with Z3 revealed two genomic regions with significantly negative dominance x additive epistatic effects. Two-way analyses of variance between marker pairs revealed nine digenic epistatic interactions: six reflecting dominance x dominance effects with variable sign and three reflecting additive x additive effects with positive sign. We conclude that heterosis for biomass-related traits in Arabidopsis has a polygenic basis with overdominance and/or epistasis being presumably the main types of gene action.

Triple and quadruple spontaneous cervical artery dissection: presenting characteristics and long-term outcome

BACKGROUND: Spontaneous cervicocephalic artery dissection (sCAD) of more than two cervical arteries is rare. PATIENTS AND METHODS: Vascular and potential sCAD risk factors, triggering events, clinical and neuroimaging findings, and outcome of patients with multiple sCAD were studied. Patients were drawn from prospective hospital-based sCAD registries. RESULTS: Of 740 consecutive patients with sCAD, 11 (1.5%) had three, and one had four (0.1%) sCAD. Eight of these 12 patients were women. One patient had additional dissections of the celiac trunk and hepatic artery. Vascular risk factors included hypertension (n = 1), hypercholesterolaemia (n = 6), current smoking (n = 5) and migraine (n = 6). No patient had a family history of sCAD, fibromuscular dysplasia (FMD) or connective tissue disease. SCAD was preceded by a minor trauma in five and infection in four patients. Clinical manifestations included ischaemic stroke (n = 8), transient ischaemic attack (n = 3), headache (n = 9), neck pain (n = 4), Horner syndrome (n = 5), pulsatile tinnitus (n = 2) and dysgeusia (n = 1). Brain MRI revealed ischaemic infarcts that affected one vessel territory in seven and two territories in two patients. The 3-month outcome was favourable (modified Rankin scale score 0-1) in 10 patients (83%). No new recurrent stroke or sCAD occurred during a mean follow-up of 50 (SD 29) months. CONCLUSION: Multiple sCAD occurred preferentially in women and caused clinical symptoms and signs mainly in one vascular territory. In none of the patients was FMD or any other underlying arteriopathy apparent. The majority of multiple sCAD was preceded by a minor trauma or infection. Clinical outcome was favourable in most patients, and long-term prognosis benign. The data suggest that transient vasculopathy may be a major mechanism for multiple sCAD.