Effects of third-neighbor interactions on the frustrated quantum Ising model

We investigate thermal and quantum phase transitions of the J_{1}-J_{2}-J_{3} transverse Ising model on the square lattice. The model is studied within a cluster mean-field decoupling, which allows us to describe phase diagrams and the free-energy landscape in the neighborhood of phase transitions. Our findings indicate that the third-neighbor coupling (J_{3}) can affect the nature of phase transitions of the model. In particular, ferromagnetic third-neighbor couplings favor the onset of continuous order-disorder phase transitions, eliminating the tricritical point of the superantiferromagnetic-paramagnetic (SAFM-PM) phase boundary. On the other hand, the enhancement of frustration introduced by weak antiferromagnetic J_{3} gives rise to the staggered dimer phase favoring the onset of discontinuous classical phase transitions. Moreover, we find that quantum annealed criticality (QAC), which takes place when the classical discontinuous phase transition becomes critical by the enhancement of quantum fluctuations introduced by the transverse magnetic field, is eliminated from the SAFM-PM phase boundary by a relatively weak ferromagnetic J_{3}. Nevertheless, this change in the nature of phase transitions can still be observed in the presence of antiferromagnetic third-neighbor couplings being also found in the staggered-dimer phase boundary. Therefore, our findings support that QAC persists under the presence of frustrated antiferromagnetic third-neighbor couplings and is suppressed when these couplings are ferromagnetic, suggesting that frustration plays a central role in the onset of QAC.

P3341Micro and macrovascular damage across the glycemic spectrum among women and men from general population

Background

Type 2 diabetes mellitus (T2DM) is a global epidemic that is strongly associated with micro- and macrovascular complications. Head to head comparisons of micro- and macrovascular dysfunction across the glycaemic spectrum among women and men from large population-based cohorts are sparse.

Purpose

To investigate associations of impaired serum fasting glucose (IFG) and T2DM with markers of micro- and macrovascular damage among women and men from general population.

Methods

We included 10,920 women and men (>45 years) from a large prospective population-based study. We applied linear and logistic regression analyses to examine the cross-sectional associations between IFG and T2DM with markers of micro- and macrovascular damage including estimated glomerular filtration rate (eGFR), retinopathy, carotid intima-media thickness (cIMT), carotid plaque (CP), carotid-femoral pulse-wave velocity (PWV), and ankle-brachial index (ABI), adjusted for cardiovascular risk factors.

Results

Mean age was 65.09±10.0 years, 11.8% had IFG and 12.2% were T2DM patients. The majority of population were women (57.2%). In the fully adjusted models, compared to individuals with normal glucose levels (<6.1 mmol/l), IFG was independently associated with PWV (β; 95% CI: 0.011; 0.002–0.021) among men. T2DM was independently associated with larger burden of CP (Odds ratio (OR); 95% CI: 1.57; 1.13–2.17), and higher eGFR (β; 95% CI: 2.17; 0.62–3.72) among women and with larger burden of retinopathy (OR; 95% CI: 1.92; 1.30–2.85), higher cIMT (β; 95% CI: 0.010; 0.01–0.02), and PWV (β; 95% CI: 0.03; 0.01–0.04) among men.

Conclusions

IFG and T2DM were associated with micro- and macrovascular damage. Compared to non-diabetics, diabetic men had larger burden for markers of microvascular damage including retinopathy while diabetic women had larger burden of macrovascular damage including CP. Both IGF and T2DM were also associated with age-related macrovascular markers such as cIMT and PWV. Proper screening of macrovascular changes at earlier stages of dysglycemia and before the overt T2DM is crucial for prevention and early treatment of end-organ damage

[Epicardial ablation of ventricular tachycardias]

Ventricular tachycardias (VT) in patients with structural heart diseases have predominantly a scar-associated reentry mechanism so that substrate-based ablation approaches also have to be used in nearly all procedures. In many VT cases-especially in nonischemic cardiomyopathy (NICM) and arrhythmogenic right ventricular cardiomyopathy-a critical epicardial substrate can be identified as an essential component of the reentry circuit so that for the ablation-based modification of the substrate in these cases an epicardial approach is necessary. In cases of redo-VT ablation procedures in ischemic cardiomyopathy (after a previously endocardial ablation), an epicardial approach should also be considered. There are also cases in whom no endocardial substrate can be identified and an isolated epicardial substrate can be identified. Worldwide epicardial VT ablations are usually performed after gaining epicardial access using subxyphoidal puncture. The results of recent studies show a higher efficiency with stabilization of cardiac rhythm and reduction of recurrent VT episodes (about 70% event-free survival at the 2‑year follow-up) after endo-plus epicardial substrate modification. In electrical storm cases, an early epicardial VT ablation approach also appears to be relevant, especially in NICM. Epicardial instrumentation and ablation represents a complex procedure which should only be performed in experienced centers with cardiac surgery back-up. In these experienced centers, the complications rate is less than 5%.

A complication probability planning study to predict the safety of a new protocol for intracranial tumour radiotherapy in dogs

Technical advances make it possible to deliver radiation therapy for canine intracranial tumours in fewer fractions, under the assumption of equivalent tumour control. With the aim of estimating the late toxicity risk profile for various tumour sizes and locations, the present paper evaluates the normal tissue complication probability (NTCP) values for the intracranial organs at risk. By making isoeffect calculations, a new 10-fraction radiation protocol was developed with the same tumour control probability (TCP) as a currently used 20-fraction standard protocol, and complication risk profiles for brain, brainstem and optic chiasm were modelled using a representative population of 64 dogs with brain tumours. For >59% of cases, the new 10-fraction protocol yielded an acceptable, low risk estimate of late toxicity (<10%). Our calculations suggest that it may be safe to treat small to intermediate-sized tumours that are neither located near the optic chiasm nor at the brainstem with 10 daily fractions of 4.35 Gy.

Transient binding accounts for apparent violation of the generalized Stokes-Einstein relation in crowded protein solutions

The effect of high concentration, also referred to as crowding conditions, on Brownian motion is of central relevance for the understanding of the physical, chemical and biological properties of proteins in their native environment. Specifically, the simple inverse relationship between the translational diffusion coefficient and the macroscopic solution viscosity as predicted by the generalized Stokes-Einstein (GSE) relation has been the subject of many studies, yet a consensus on its applicability has not been reached. Here, we use isotope-filtered pulsed-field gradient NMR to separately assess the μm-scale diffusivity of two proteins, BSA and an SH3 domain, in mixtures as well as single-protein solutions, and demonstrate that transient binding can account for an apparent violation of the GSE relation. Whereas GSE behavior applies for the single-protein solutions, it does not hold for the protein mixtures. Transient binding behavior in the concentrated mixtures is evidenced by calorimetric experiments and by a significantly increased apparent activation energy of diffusion. In contrast, the temperature dependence of the viscosity, as well as of the diffusivity in single-component solutions, is always dominated by the flow activation energy of pure water. As a practically relevant second result, we further show that, for high protein concentrations, the diffusion of small molecules such as dioxane or water is not generally a suitable probe for the viscosity experienced by the diffusing proteins.

Outcome in dogs with advanced (stage 3b) anal sac gland carcinoma treated with surgery or hypofractionated radiation therapy

Stage 3b anal sac gland carcinoma (ASGC) can be life-threatening. A surgical approach is not always possible or may be declined. Dogs with stage 3b ASGC treated with surgery or conformal radiation therapy (RT) with 8 × 3.8 Gy (total dose 30.4 Gy, over 2.5 weeks) were retrospectively evaluated. Patient characteristics, median progression-free interval (PFI) and median survival time (MST) were compared. Twenty-eight dogs were included; 15 underwent surgery, 13 underwent RT. At the time of presentation, 21% showed life-threatening obstipation and 25% showed hypercalcaemia. PFI and MST for surgery cases were 159 days (95% CI: 135-184 days) and 182 days (95% CI: 146-218 days), both significantly lower than for RT cases with 347 days (95% CI: 240-454 days) and 447 days (95% CI: 222-672 days), (P = 0.01, P = 0.019). Surgery as well as RT led to a fast relief of symptoms. PFI and survival of surgical patients were significantly inferior to that of a comparable patient group treated with conformal hypofractionated RT.

Behavioral characterization of striatal-enriched protein tyrosine phosphatase (STEP) knockout mice

Striatal-enriched protein tyrosine phosphatase (STEP) has been described as a regulator of multiple kinases and glutamate receptor subunits critical for synaptic plasticity. Published behavioral and biochemical characterization from the founder line of STEP knockout (KO) mice revealed superior cognitive performance, with enhanced phosphorylation of substrates such as ERK, Fyn and GluN2B; suggesting that inhibitors of STEP may have potential as therapeutic agents for the treatment of neuropsychiatric disorders. The objectives of this work aimed to replicate and extend the previously reported behavioral consequences of STEP knockout. Consistent with previous reported data, STEP KO mice demonstrated exploratory activity levels and similar motor coordination relative to WT littermate controls as well as intact memory in a Y-maze spatial novelty test. Interestingly, KO mice demonstrated deficits in pre-pulse inhibition as well as reduced seizure threshold relative to WT controls. Immunohistochemical staining of brains revealed the expected gene-dependent reduction in STEP protein confirming knockout in the mice. The present data confirm expression and localization of STEP and the absence in KO mice, and describe functional downstream implications of reducing STEP levels in vivo.

Stability against brushing abrasion and the erosion-protective effect of different fluoride compounds

This study aimed to analyse the impact of brushing on the protective effect of different fluoride solutions on enamel and dentin erosion. Bovine enamel and dentin specimens were rinsed once with TiF4, AmF, SnF2 (0.5 M F, 2 min) or water (control). Specimens were either left unbrushed or brushed with 10, 20, 50, 100 or 500 brushing strokes in an automatic brushing machine (2 N, non-fluoridated toothpaste slurry). Ten specimens per group were eroded with hydrochloric acid (HCl) (pH 2.3) for 60 s, and calcium release into the acid was determined by atomic absorption spectroscopy. Additionally, enamel and dentin surfaces were analysed by X-ray energy-dispersive spectroscopy (EDS) (n = 6/group) and scanning electron microscopy (SEM) (n = 2/group) before brushing and after 500 brushing strokes. Statistical analysis (p < 0.05) was performed by three- and one-way ANOVA (calcium release) or repeated measures ANOVA (EDS). TiF4, AmF and SnF2 reduced the erosive calcium loss in unbrushed specimens to 58-67% (enamel) and 23-31% (dentin) of control. Calcium release increased with increasing brushing strokes prior to erosion and amounted to 70-88% (enamel) and 45-78% (dentin) of control after 500 brushing strokes. Brushing reduced the surface concentration of fluoride (AmF), tin (SnF2) and titanium (TiF4). SEM revealed that surface precipitates were affected by long-term brushing. Brushing reduced the protective potential of TiF4, AmF and SnF2 solutions. However, considering a small number of brushing strokes, the protective effect of fluoride solutions is only slightly affected by brushing abrasion.

Interdental cleaning and gingival injury potential of interdental toothbrushes

The effective cleaning of interdental spaces using toothbrushes is a challenge. The aim of the present in vitro study was to evaluate on the one hand the interdental cleaning efficiency and on the other hand the gingival injury potential of an electric single-headed sonic toothbrush (Water-pik) and two single-tufted manual toothbrushes (Curaprox 1009; Lactona Interdental Brush). Brushes were evaluated using a brushing device. Test dental casts (maxillary sextants) consisting of black teeth coated with white paint were brushed using standardized horizontal movements. Thereafter, black (i.e. cleaned) areas were measured planimetrically. The soft tissue injury potential was evaluated using front segments of porcine mandibles. In the same brushing device, test brushes were moved over the gingiva. Before and after each treatment, the porcine mucosa was stained with a plaque disclosing agent to visualize injured areas, which could then be measured planimetrically as well. These evaluations were each made after 15, 30, 60, and 120 seconds of brushing. The statistical analysis was performed using non-parametric Mann-Whitney tests, and the level of significance was set at 5%. The best cleaning performance of 46% across all interdental spaces assessed was found with the electric sonic toothbrush (Waterpik), while the performances of the manual brushes from Lactona and Curaprox were 14.8% and 5%, respectively. At each point of evaluation, the gingiva was injured most markedly by the powered sonic toothbrush (Waterpik), followed by the manual Curaprox brush. The smallest damage of the porcine gingiva was produced by the manual Lactona brush. When comparing the manual toothbrushes, the Lactona product revealed a better cleaning performance combined with a smaller injury potential than the Curaprox brush. Thus, the prophylactic goal to achieve high degrees of cleaning while producing minimal damage is important and should have priority when evaluating and selecting toothbrushes.

Association of BK viremia with human leukocyte antigen mismatches and acute rejection, but not with type of calcineurin inhibitor

INTRODUCTION

BK viremia and polyomavirus-associated nephropathy (PVN) represent a significant problem after kidney transplantation. Both are associated with intensified immunosuppression, but other risk factors and the impact of a screening program on outcome are incompletely understood.

METHODS

Here, we report on the short- and long-term outcome of a cohort of patients, who were transplanted in 2006/2007 and included in a newly introduced systematic 3-monthly screening for BK viremia at the University Hospital Zurich. In patients testing positive for BK viremia, screening frequency was intensified and immunosuppression reduced. Patients with suspected PVN underwent transplant biopsy.

RESULTS

Among 152 included patients, 49 (32%) tested positive for BK viremia, but only 8 developed biopsy-proven PVN. BK viremia had a significant impact on estimated glomerular filtration rate and proteinuria in the first 2 years. Acute rejection episodes and the number of human leukocyte antigen (HLA) mismatches were the strongest independent predictors of BK viremia in a multiple logistic model. In contrast, no particular immunosuppressive agent or regimen was associated with enhanced risk.

CONCLUSION

Taken together, systematic BK viremia screening led to detection of a high percentage of viremic patients. With adjustment of immunosuppression, an excellent outcome was achieved. The independent association of HLA mismatches with BK viremia suggests impaired polyomavirus immunosurveillance in highly mismatched allografts.

Identification and characterization of a defective CYP3A4 genotype in a kidney transplant patient with severely diminished tacrolimus clearance

Cytochrome P450 3A4 (CYP3A4) is a major drug-metabolizing enzyme that is widely investigated. So far, no homozygous inactive variant has been described. We report on a 19-year-old kidney transplant patient suffering from Alport syndrome, who experienced unexpected high tacrolimus plasma trough levels during immunosuppressant therapy. Because nonadherence, liver failure, or drug-drug interactions could be excluded, we hypothesized a diminished metabolism of the drug caused by mutations in the main detoxification enzyme, CYP3A4. Exome sequencing revealed a novel single-nucleotide polymorphism (c.802C>T) resulting in a premature stop codon in CYP3A4 exon 5. Accordingly, no CYP3A4 protein could be detected in kidney biopsy tissue, and there was lack of expression in HepG2 cells transiently transfected with the mutated CYP3A4. In addition, the patient harbored inactive CYP3A5*3, resulting in loss of function of the entire CYP3A locus, explaining the deteriorated tacrolimus clearance. This is, to our knowledge, the first case of a complete failure of CYP3A4 in humans.

Quantitative sensory testing of intraoral open wounds

Wound healing is an important aspect of oral and maxillofacial surgery. Positive sensory signs (allodynia, hyperalgesia) and negative sensory signs (hypoesthesia, hypoalgesia) may be encountered. Quantitative sensory testing (QST) has moved from bench to bedside for the detection, therapy selection and monitoring the recovery of individuals with sensory disturbances. Tracking somatosensory changes during normal and abnormal wound healing has not previously been reported. This report presents data obtained by a novel, automated, non-contact psychophysical method for assessment of wound sensitivity after standardized oral mucosal biopsy. By directing graded air puffs towards palatal biopsy wounds, thresholds for sensory detection, pain detection and pain tolerance were repeatedly assessed across 19 days, demonstrating high reliability. Participants recorded daily spontaneous and chewing-evoked maximum pains. Pain detection and tolerance thresholds increased linearly across time. Comparison between air puff evoked pain detection threshold and chewing-evoked pain demonstrated a strong correlation. Thus, for the first time, this study tracked the time course of somatosensory sensitivity of wounds induced by oral biopsies. The psychophysical data on wound healing obtained by this automated, contact-free stimulation method can be utilized as a surrogate marker for clinical pain improvements and standardized assessment of intraoral pain sensitivity, for example in oral mucositis.

The effect of dentin desensitizer on shear bond strength of conventional and self-adhesive resin luting cements after aging

This study tested the impact of Gluma Desensitizer on the shear bond strength (SBS) of two conventional (RelyX ARC, Panavia 21) and two self-adhesive (RelyX Unicem, G-Cem) resin luting cements after water storage and thermocycling. Human third molars (N=880) were embedded in acrylic resin. The buccal dentin was exposed. Teeth were randomly divided into four main groups, and the following cements were adhered: 1) RelyX ARC, 2) Panavia 21, 3) RelyX Unicem, and 4) G-Cem. In half of the teeth in each group, dentin was treated with Gluma Desensitizer. In the conventional cement groups, the corresponding etchant and adhesive systems were applied. SBS of the cements was tested after 1 hour (initial); at 1, 4, 9, 16, and 25 days of water storage; and at 1, 4, 9, 16, and 25 days of thermocycling. SBS data were analyzed by one-way analysis of variance (ANOVA); this was followed by the post hoc Scheffé test and a t-test. Overall, the highest mean SBS (MPa) was obtained by RelyX ARC (ranging from 14.6 ± 3.9 to 17.6 ± 5.2) and the lowest by Panavia 21 in combination with Gluma Desensitizer (ranging from 0.0 to 2.9 ± 1.0). All tested groups with and without desensitizer showed no significant decrease after aging conditions compared with baseline values (p>0.05). Only the Panavia 21/Gluma Desensitizer combination showed a significant decrease after 4 days of thermocyling compared with initial values and 1 day thermocycling. Self-adhesive cements with Gluma Desensitizer showed increased SBS after aging conditions (ranging from 7.4 ± 1.4 to 15.2 ± 3) compared with groups without desensitizer (ranging from 2.6 ± 1.2 to 8.8 ± 2.9). No cohesive failures in dentin were observed in any of the test groups. Although self-adhesive cements with and without desensitizer presented mainly adhesive failures after water storage (95.8%) and thermocyling (100%), conventional cement (RelyX ARC) showed mainly mixed failures (90.8% and 89.2%, after water storage and thermocyling, respectively). Application of the Gluma Desensitizer to dentin before cementation had a positive effect on the SBS of self-adhesive cements.

[Approaches to reduce shortage of general practitioners in rural areas--results of an online survey of trainee doctors]

BACKGROUND

In times of shortage of general practitioners (GPs), especially in rural areas, it is of particular interest to explore expectations and interests of GP trainees relating to their future work. The aim of this study was, to survey the willingness of trainee doctors to work in or open a general practice, as well as their expectations and plans concerning future work as a GP in a rural area.

METHODS

The survey was conducted online between April to October 2010 with trainee doctors. The questionaire contained 25 questions about the trainees' sociodemographic status, expectations and conception of their future work, factors influencing setting up a GP practice and their ideas about working in a rural area.

RESULTS

528 trainee doctors from across Germany responded. More than half of them were female, more than 40% older than 35 years. 89% could image themselves settling in a GP practice, 77% in a rural area. The three most important factors influencing working in a rural practice were family friendly surrounding, the rural village itself and cooperation with colleagues. Most trainees would accepted having to travel 30 minutes to work.

CONCLUSION

As the basic willingness to set up practice in rural areas is quite high, relevant influencing factors such as family friendly surroundings, out-of-hour services arrangements und working models offering the opportunity to work in group handed practices should be emphasized in recruitment.

Product gas evolution above planar microstructured model catalysts--a combined scanning mass spectrometry, Monte Carlo, and Computational Fluid Dynamics study

The transport and distribution of reaction products above catalytically active Pt microstructures was studied by spatially resolved scanning mass spectrometry (SMS) in combination with Monte Carlo simulation and fluid dynamics calculations, using the oxidation of CO as test reaction. The spatial gas distribution above the Pt fields was measured via a thin quartz capillary connected to a mass spectrometer. Measurements were performed in two different pressure regimes, being characteristic for ballistic mass transfer and diffusion involving multiple collisions for the motion of CO(2) product molecules between the sample and the capillary tip, and using differently sized and shaped Pt microstructures. The tip height dependent lateral resolution of the SMS measurements as well as contributions from shadowing effects, due to the mass transport limitations between capillary tip and sample surface at close separations, were evaluated and analyzed. The data allow to define measurement and reaction conditions where effects induced by the capillary tip can be neglected ("minimal invasive measurements") and provide a basis for the evaluation of catalyst activities on microstructured model systems, e.g., for catalyst screening or studies of transport effects.

Histiocytic sarcomas in flat-coated retrievers: a summary of 37 cases (November 1998-March 2005)

Thirty-seven cases of histiocytic-like sarcomas (HLSs) in flat-coated retriever dogs were evaluated retrospectively. This tumour accounted for 36% of the malignant tumours seen in this breed during the study period. The median age at presentation was 8.2 years. Thirty-four dogs presented with a swelling or mass in a muscle group or surrounding a joint. The remaining three presented for rib (1), cutaneous (1) or primary splenic origin (1). A high rate of metastasis to local lymph nodes (45%), thorax (20%) and abdominal organs (20% confirmed) was seen. Overall metastastic rate by the time of death was 70%. The median survival for all dogs was 123 days. The most significant prognostic indicator was presence of distant metastasis at the time of diagnosis with median survival of 68 or 200 days, with or without metastasis, respectively. Chemotherapy and radiation therapy significantly improved survival. Dogs given chemotherapy survived a median of 185 versus 34 days for dogs that were not (P = 0.0008). Dogs treated with radiation survived a median of 182 versus 60 days for those that were not (P = 0.0282). Dogs receiving only palliative therapy survived a median of 17 versus 167 days in dogs receiving any kind of radiation, chemotherapy, surgery or combinations. A set protocol of radiation and CCNU (RTCCNU) induced minimal toxicity and provided a median survival of 208 versus 68 days for all other dogs. While this tumour carries a poor long-term prognosis in flat-coated retrievers, it is reasonable to treat these dogs for palliation of signs and extension of life.

Fisher-Lewis kidney transplantation model as a tool for investigation of transplantation-induced cardiomyopathy

BACKGROUND

Cardiovascular disease is a major cause of death after kidney transplantation; thus, cardiovascular protection is a major concern in transplant recipients. Data about cardiac characteristics from animal models after kidney transplantation are lacking. Therefore, we investigated cardiac structure and function in a model of chronic allograft injury.

METHODS

Kidneys from Fisher 344 rats were orthotopically transplanted into Lewis rats. Eight recipient rats were treated with placebo or an angiotensin II type-1 receptor blocker (AT1RB; candesartan cilexitil, 5 mg/kg/d) for 24 weeks posttransplantation, and 8 untreated matched Lewis rats were used as healthy controls. Echocardiography was performed at 24 weeks posttransplantation to measure ejection fraction, fractional shortening, and left ventricular mass, in triplicate. Proteinuria at 24 hours was determined, and after harvesting, the heart weight-body weight ratio (HW/BW) was measured.

RESULTS

At 24 weeks posttransplantation, renal transplant-recipient rats demonstrated a significantly decreased ejection fraction (mean [SD], 58.9% [3.2%] vs 70.7% [2.1%]) and fractional shortening (29.8% [2.0%] vs 38.3% [2.0%]) and increased HW/BW and left ventricular mass (7.7 [0.2] cm(3) vs 6.7 [0.2] cm(3)) compared with healthy control rats. The HW/BW and left ventricular mass were significantly ameliorated by AT1RB compared with placebo-treated transplant-recipient rats (6.8 [0.2] cm(3) vs 7.7 [0.2] cm(3)). In addition, decreased proteinuria was evident after AT1RB.

CONCLUSION

The Fisher-Lewis rat kidney transplantation model resulted in cardiac hypertrophy and decreased cardiac function. AT1RB normalized cardiac hypertrophy without improving function. These findings demonstrate that the Fisher-Lewis rat renal transplantation model can be used to investigate transplantation-induced cardiomyopathy.