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.