Metastable chaos in the ammonia ring laser

We report experimental studies of metastable chaos in the far-infrared ammonia ring: laser. When the laser pump power is switched from above chaos threshold to slightly below, chaotic intensity pulsations continue for a varying time afterward before decaying to either periodic or cw emission. The behavior is in good qualitative agreement with that predicted by the Lorenz equations, previously used to describe this laser. The statistical distribution of the duration of the chaotic transient is measured and shown to be in excellent agreement with the Lorenz equations in showing a modified exponential distribution. We also give a brief numerical analysis and graphical visualization of the Lorenz equations in phase space illustrating the boundary between the metastable chaotic and the stable fixed point basins of attraction. This provides an intuitive understanding of the metastable dynamics of the Lorenz equations and the experimental system.

Treatment of ring slippage after gastric bypass: long-term results after endoscopic dilation with an achalasia balloon (with videos)

Background: Silastic rings are used in gastric bypass procedures for the treatment of obesity, but ring slippage may lead to gastric pouch outlet stenosis (GPOS). Conventional management has been ring removal through abdominal surgery. Objective: To describe a novel, safe, minimally invasive, endoscopic technique for the treatment of GPOS caused by ring slippage after gastric bypass. Design: Case series. Setting: Federal University of Pernambuco and sao Paulo University. Patients: This study involved 39 consecutive patients who-were screened for inclusion. Intervention: Endoscopic dilation with an achalasia balloon. Main Outcome Measurements: Technical success and safety of the procedure. Results: Among the 39 patients, 35 underwent endoscopic dilation at the ring slippage site for the relief of GPOS. The 4 patients who did not undergo endoscopic dilation underwent surgical removal of the ring, based on the exclusion criteria. The endoscopic approach was successful in 1 to 4 sessions in 100% of cases with radioscopic control (n = 12). The duration of the procedures ranged from 5 to 30 minutes, and the average internment was 14.4 hours. Dilation promoted either rupture (65.7%) or stretching (34.3%) of the thread within the ring, thereby increasing the luminal diameter of the GPOS. Complications included self-limited upper digestive tract hemorrhage (n = 1) and asymptomatic ring erosion (n = 4). There were no recurrences of obstructive symptoms during the follow-up period (mean of 33.3 months). Limitations: This was not a randomized, comparison study, and the number of patients was relatively small. Conclusion: The technique described promotes the relief of GPOS with low overall morbidity and avoids abdominal reoperation for ring removal. (Gastrointest Endosc 2010;72:44-9.)

Molybdenum carbonyl complexes of pendant-arm polyazamacrocycles

Molybdenum hexacarbonyl reacted with the pendant-arm macrocycles 10-methyl-1,4,8, 12-tetraazacyclopentadecane-10-amine (L-1) and trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6, 13-diamine (L-2) in the absence of air to form complexes fac-[MoL1(CO)(3)] and [Mo2L2(CO)(8)] respectively. The mononuclear complex has the macrocycle bound in a tridentate manner, including the pendant primary amine, whereas the dinuclear complex exhibits a bridging bis(didentate) co-ordination mode, again involving the pendant primary amines. Structures have been defined by crystal structure analyses. The preferential binding of the pendant primary amines rather than additional secondary amines parallels similar behaviour observed earlier with some mercury(II) and rhodium(III) complexes, and points to the important general role of this pendant, despite being fused directly to the macrocyclic ring, in metal-ion binding.

Photodegradation of irinotecan (CPT-11) in aqueous solutions: Identification of fluorescent products and influence of solution composition

The photodegradation of irinotecan (CPT-11), the semisynthetic derivative of the antitumor alkaloid 20(S)-camptothecin, has been investigated. The drug was exposed to laboratory light for up to 5 days in 0.9% saline solution (pH 8.5). Five significant photodegradation products were observed and a high-performance liquid chromatography (HPLC) assay was employed to isolate them from CPT-11 using gradient conditions. The structures were elucidated by nuclear magnetic resonance spectroscopy and tandem mass spectrometry and shown to be the result of extensive modifications of the lactone ring of CPT-11. Three of the compounds were found to belong to the mappicine group of alkaloids. In addition, the effect of light on the stability of CPT-11 in aqueous solutions and biological fluids was also assessed, Potassium phosphate buffers (0.05 M, pH 5.0-8.2) and saline, plasma, urine, and bile solutions containing 20 mu M CPT-11 were equilibrated in the dark for 24 h before being exposed to laboratory light for up to 171 h at ambient temperature. Four of the five identified photodegradation products were observed and quantitated by isocratic HPLC, using a different detection mode (fluorescence) than the one used for gradient elution, In general, CPT-11 was found to be unstable under neutral and alkaline conditions for all solutions investigated, with the exception of bile. We conclude that CPT-11 is photolabile and that care should be taken to protect samples, particularly those intended for the isolation and identification of novel metabolites of CPT-11.

Anemia During Pregnancy after Silastic Ring Roux-en-Y Gastric Bypass: Influence of Time to Conception

Bariatric surgery before pregnancy may help prevent obesity-related gestational complications. However, maternal malnutrition is not without potential risks during pregnancy. The objective was to evaluate the influence of time to conception after silastic ring Roux-en-Y gastric bypass (SRYGB) on maternal anemia. Patients who underwent SRYGB for morbid obesity and who subsequently became pregnant were followed up at the prenatal. Thirty pregnancies occurred between July 2001 and September 2009. The patients were analyzed according to time to conception after bariatric surgery: 17 patients with time to conception < 4 years (48 months) and 13 patients with a parts per thousand yen4 years. First trimester hemoglobin levels were significantly lower in patients with time to conception a parts per thousand yen4 years (48 months) (median 9.6 g/dL, range 5.8-13.2 g/dL) than in patients with time to conception < 4 years (median 11.1 g/dL, range 9.8-13.6 g/dL; p = 0.047). The need for intravenous iron therapy or packed red cell transfusion was significantly more frequent among women who became pregnant a parts per thousand yen4 years after SRYGB compared to < 4 years (30.8% vs. 0%, p = 0.026). Pregnancy after 4 years of SRYGB is associated with maternal anemia and the need for more strict iron supplementation.

Cytogenetic and Molecular Evaluation and 20-Year Follow-Up of a Patient With Ring Chromosome 14

We present a 20-year follow-up on a patient with a ring chromosome 14. The ring chromosome was studied by fluorescence in-situ hybridization (FISH), multiplex-ligation probe amplification (MLPA), and genome wide SNP array, and no deletions of chromosome 14 were detected, although the telomeric repeat sequence was absent from the ring chromosome. The patient had skeletal abnormalities, and susceptibility to infections, as well as seizures and retinal pigmentation, which are commonly found in individuals with a ring 14. Our patient corroborates the idea that even when no genes are lost during ring formation, a complete ring chromosome can produce phenotypic alterations, which presumably result from ring instability or gene silencing due to the new chromosomal architecture. (C) 2010 Wiley-Liss, Inc.

Cytoplasmic and nuclear localization of cadherin in honey bee (Apis mellifera L.) gonads

Cadherins are crucial molecules mediating cell-cell interactions between somatic and germline cells in insect and mammalian male and female gonads. We analysed the presence and localization of cadherins in ovaries of honeybee queens and in testes of drones. Transcripts representing two classical cadherins, E-cadherin (shotgun) and N-cadherin, as well as three protocadherins (Starry night, Fat and Fat-like) were detected in gonads of both sexes. Pan-cadherin antibodies, which most probably detect a honeybee N-cadherin, were used in immunolocalization analyses. In the germarium of ovarioles, cadherin-IR (cadherin immunoreactivity) was evidenced as homogeneously distributed in the cytoplasm and as nuclear foci, in both germline and somatic cells. It was also detected in polyfusomes and ring canals. In testiolar tubules, cadherin-IR showed a cytoplasmic and nuclear distributon alike in ovaries. The unexpected nuclear localization and cytoplasmic distribution in ovaries and testes were corroborated by immunogold electron microscopy, which revealed cadherin aggregates associated with electron-dense nuclear structures. With respect to cadherin localization, the honeybee differs from Drosophila, the model for gametogenesis in insects, raising the question as to how differences among solitary and social species may be built into and generated from the general architecture of polytrophic meroistic ovaries. It also indicates the possibility of divergent roles for cadherin in the functional architecture of insect gonads, in general, especially in taxa with high reproductive output.

A combined study of behavior and Fos expression in limbic structures after re-testing Wistar rats in the elevated plus-maze

The elevated plus-maze is an animal model used to study anxiety. In a second session, rats show a reduction in the exploratory behavior even when the two sessions are separated by intervals as large as 7 days. The aim of the present study was to investigate whether the reduction in the exploratory behavior is maintained after intervals larger than 7 days. Additionally, we aimed at investigating eventual correlations between behaviors in the plus-maze and activation of limbic structures as measured by Fos protein expression after the second session. Rats were tested for 5 min in the elevated plus-maze and re-tested 3, 9 or 33 days later. Other groups were tested only once. The rat brains were processed for immunohistochemical detection of Fos protein. The results show a decrease in the open arms exploration in the second trial with intervals of 3, 9 and 33 days. The expression of Fos protein in the piriform cortex, septal nucleus and paraventricular hypothalamic nucleus in the groups tested with intervals of 9 and 33 days were statistically different from the other groups. The alterations observed in exploratory behavior in the second session in the plus-maze did not correlate with Fos expression. In conclusion, although the specific test conditions were sufficient to evoke behavioral alterations in exploration in the elevated plus-maze, they were enough to induce significant Fos protein expression in piriform cortex, septal nucleus and thalamic and hypothalamic paraventricular nuclei but not in other areas such as dorsomedial nucleus of the hypothalamus and amygdala nuclei, known to be also active participants in circuits controlling fear and anxiety. (C) 2010 Elsevier Inc. All rights reserved.

Network structures of Bis-GMA/TEGDMA resins differ in DC, shrinkage-strain, hardness and optical properties as a function of reducing agent

Objectives. To evaluate the influence of different tertiary amines on degree of conversion (DC), shrinkage-strain, shrinkage-strain rate, Knoop microhardness, and color and transmittance stabilities of experimental resins containing BisGMA/TEGDMA (3: 1 wt), 0.25wt% camphorquinone, 1wt% amine (DMAEMA, CEMA, DMPT, DEPT or DABE). Different light-curing protocols were also evaluated. Methods. DC was evaluated with FTIR-ATR and shrinkage-strain with the bonded-disk method. Shrinkage-strain-rate data were obtained from numerical differentiation of shrinkage-strain data with respect to time. Color stability and transmittance were evaluated after different periods of artificial aging, according to ISO 7491: 2000. Results were evaluated with ANOVA, Tukey, and Dunnett`s T3 tests (alpha = 0.05). Results. Studied properties were influenced by amines. DC and shrinkage-strain were maximum at the sequence: CQ < DEPT < DMPT <= CEMA approximate to DABE < DMAEMA. Both DC and shrinkage were also influenced by the curing protocol, with positive correlations between DC and shrinkage-strain and DC and shrinkage-strain rate. Materials generally decreased in L* and increased in b*. The strong exception was the resin containing DMAEMA that did not show dark and yellow shifts. Color varied in the sequence: DMAEMA < DEPT < DMPT < CEMA < DABE. Transmittance varied in the sequence: DEPT approximate to DABE < DABE approximate to DMPT approximate to CEMA < DMPT approximate to CEMA approximate to DMAEMA, being more evident at the wavelength of 400 nm. No correlations between DC and optical properties were observed. Significance. The resin containing DMAEMA showed higher DC, shrinkage-strain, shrinkage-strain rate, and microhardness, in addition to better optical properties. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Strong Grobner bases for polynomials over a principal ideal ring

Grobner bases have been generalised to polynomials over a commutative ring A in several ways. Here we focus on strong Grobner bases, also known as D-bases. Several authors have shown that strong Grobner bases can be effectively constructed over a principal ideal domain. We show that this extends to any principal ideal ring. We characterise Grobner bases and strong Grobner bases when A is a principal ideal ring. We also give algorithms for computing Grobner bases and strong Grobner bases which generalise known algorithms to principal ideal rings. In particular, we give an algorithm for computing a strong Grobner basis over a finite-chain ring, for example a Galois ring.