Metformin shows anti-neoplastic properties by inhibition of oxidative phosphorylation and glycolysis in epidermolysis bullosa-associated aggressive cutaneous squamous cell carcinoma

BACKGROUND

While most cutaneous squamous cell carcinomas (cSCCs) are treatable, certain high-risk cSCCs, such as those in recessive dystrophic epidermolysis bullosa (RDEB) patients, are particularly aggressive. Owing to repeated wounding, inflammation and unproductive healing, RDEB patients have a 68% cumulative risk of developing life-threatening cSCCs by the age of 35, and a 70% risk of death by the age of 45. Despite aggressive treatment, cSCC represents the leading cause of premature mortality in these patients, highlighting an unmet clinical need. Increasing evidence points to a role of altered metabolism in the initiation and maintenance of cSCC, making metabolism a potential therapeutic target.

OBJECTIVES

We sought to determine the feasibility of targeting tumour cell energetics as a strategy to selectively hinder the growth advantage of aggressive cSCC.

METHODS

We evaluated the cell energetics profiles of RDEB-SCC cells by analysing available gene expression data against multiple gene signatures and single-gene targets linked to metabolic reprogramming. Additionally, we employed real-time metabolic profiling to measure glycolysis and respiration in these cells. Furthermore, we investigated the anti-neoplastic properties of the metformin against human and murine high-risk cSCCs in vitro and in vivo.

RESULTS

Gene expression analyses highlighted a divergence in cell energetics profiles between RDEB-SCC and non-malignant RDEB keratinocytes, with tumour cells demonstrating enhanced respiration and glycolysis scores. Real-time metabolic profiling supported these data and additionally highlighted a metabolic plasticity of RDEB-SCC cells. Against this background, metformin exerted an anti-neoplastic potential by hampering both respiration and glycolysis, and by inhibiting proliferation in vitro. Metformin treatment in an analogous model of fast-growing murine cSCC resulted in delayed tumour onset and slower tumour growth, translating to a 29% increase in median overall survival.

CONCLUSIONS

Our data indicate that metformin exerts anti-neoplastic properties in aggressive cSCCs that exhibit high-risk features by interfering with respiration and glycolytic processes.

Precomputed Radiative Heat Transport for Efficient Thermal Simulation

Architectural design and urban planning are complex design tasks. Predicting the thermal impact of design choices at interactive rates enhances the ability of designers to improve energy efficiency and avoid problematic heat islands while maintaining design quality. We show how to use and adapt methods from computer graphics to efficiently simulate heat transfer via thermal radiation, thereby improving user guidance in the early design phase of large-scale construction projects and helping to increase energy efficiency and outdoor comfort. Our method combines a hardware-accelerated photon tracing approach with a carefully selected finite element discretization, inspired by precomputed radiance transfer. This combination allows us to precompute a radiative transport operator, which we then use to rapidly solve either steady-state or transient heat transport throughout the entire scene. Our formulation integrates time-dependent solar irradiation data without requiring changes in the transport operator, allowing us to quickly analyze many different scenarios such as common weather patterns, monthly or yearly averages, or transient simulations spanning multiple days or weeks. We show how our approach can be used for interactive design workflows such as city planning via fast feedback in the early design phase.

Therapeutic assessment of N-formyl-methionyl-leucyl-phenylalanine (fMLP) in reducing periprosthetic joint infection

Despite many preventive measures, including prophylactic antibiotics, periprosthetic joint infection (PJI) remains a devastating complication following arthroplasty, leading to pain, suffering, morbidity and substantial economic burden. Humans have a powerful innate immune system that can effectively control infections, if alerted quickly. Unfortunately, pathogens use many mechanisms to dampen innate immune responses. The study hypothesis was that immunomodulators that can jumpstart and direct innate immune responses (particularly neutrophils) at the surgical site of implant placement would boost immune responses and reduce PJI, even in the absence of antibiotics. To test this hypothesis, N-formyl-methionyl-leucyl-phenylalanine (fMLP) (a potent chemoattractant for phagocytic leukocytes including neutrophils) was used in a mouse model of PJI with Staphylococcus aureus (S. aureus). Mice receiving intramedullary femoral implants were divided into three groups: i) implant alone; ii) implant + S. aureus; iii) implant + fMLP + S. aureus. fMLP treatment reduced S. aureus infection levels by ~ 2-Log orders at day 3. Moreover, fMLP therapy reduced infection-induced peri-implant periosteal reaction, focal cortical loss and areas of inflammatory infiltrate in mice distal femora at day 10. Finally, fMLP treatment reduced pain behaviour and increased weight-bearing at the implant leg in infected mice at day 10. Data indicated that fMLP therapy is a promising novel approach for reducing PJI, if administered locally at surgical sites. Future work will be toward further enhancement and optimisation of an fMLP-based therapeutic approach through combination with antibiotics and/or implant coating with fMLP.

Fretting-corrosion of CoCr-alloys against TiAl6V4: The importance of molybdenum in oxidative biological environments

Periprosthetic fluids often contain reactive oxygen species, including H₂O₂, that are generated during inflammatory processes. Here, we investigated the fretting-corrosion behavior of CoCrX-alloys (X = Mo, Fe) in a complex protein-containing lubricant, with and without the addition of H₂O₂. Given the known protective role of molybdenum as an alloying element in metal degradation, we considered its effects by designing a two-way factorial experiment. The aim of the study was to investigate tribocorrosive mechanisms in modular joints of knee and hip prostheses. A previously described test-rig was used to run fretting corrosion tests of CoCrX-alloys with (X=Mo) and without (X=Fe) molybdenum against TiAl6V4 in bovine calf serum (BCS) with and without a physiological relevant H₂O₂ level (3 mM) in gross slip mode (4 Hz, ±50 μm, p_max=0.18 GPa, 37 °C, 50,000 cycles). Two CoCr-pins were pressed against a cylindrical TiAl6V4-rod, forming a line contact. Normal and frictional forces, the displacement, and the open circuit potential (OCP) were measured and recorded continuously. The dissipated frictional work was independent of alloy composition. The addition of H₂O₂ lowered the dissipated frictional work and increased wear, and this was significant in the absence of Mo. The mean OCP value was lower with Mo-containing than with Mo-free alloy in both pure BCS (p = .042), and BCS ± H₂O₂ (p < .0005). The wear scar was deeper for the Mo-free alloy, and this was significant (p = .013) in the presence of H₂O₂. These findings suggest a marked weakening of the passive film in the presence of H₂O₂, which is mitigated by the availability of Mo.

Quantized conductance doubling and hard gap in a two-dimensional semiconductor-superconductor heterostructure

Coupling a two-dimensional (2D) semiconductor heterostructure to a superconductor opens new research and technology opportunities, including fundamental problems in mesoscopic superconductivity, scalable superconducting electronics, and new topological states of matter. One route towards topological matter is by coupling a 2D electron gas with strong spin–orbit interaction to an s-wave superconductor. Previous efforts along these lines have been adversely affected by interface disorder and unstable gating. Here we show measurements on a gateable InGaAs/InAs 2DEG with patterned epitaxial Al, yielding devices with atomically pristine interfaces between semiconductor and superconductor. Using surface gates to form a quantum point contact (QPC), we find a hard superconducting gap in the tunnelling regime. When the QPC is in the open regime, we observe a first conductance plateau at 4e²/h, consistent with theory. The hard-gap semiconductor–superconductor system demonstrated here is amenable to top-down processing and provides a new avenue towards low-dissipation electronics and topological quantum systems.

Interface transparency between 2D semiconductors and superconductors is a longstanding problem, seriously hindering potential applications. Here, using a new hybrid system, Kjaergaard et al. report quantized conductance doubling and a hard superconducting gap measured via a quantum point contact, indicating a near pristine interface.

Pollen-derived nonallergenic substances enhance Th2-induced IgE production in B cells

BACKGROUND

B cells play a central role in IgE-mediated allergies. In damaged airway epithelium, they are exposed directly to aeroallergens. We aimed to assess whether direct exposure of B cells to pollen constituents affects allergic sensitization.

METHODS

B cells from murine splenocytes and from blood samples of healthy donors were incubated for 8 days under Th2-like conditions with aqueous ragweed pollen extracts (Amb-APE) or its constituents. Secreted total IgM, IgG, and IgE was quantified by ELISA. Additionally, birch, grass, or pine-pollen extracts were tested. The number of viable cells was evaluated by ATP measurements. B-cell proliferation was measured by CFSE staining. IgE class switch was analyzed by quantitation of class switch transcripts. In an OVA/Alum i.p.-sensitization mouse model, Amb-APE was intranasally instilled for 11 consecutive days.

RESULTS

Upon Th2 priming of murine B cells, ragweed pollen extract caused a dose-dependent increase in IgE production, while IgG and IgM were not affected. The low-molecular-weight fraction and phytoprostane E1 (PPE1) increased IgE production, while Amb a 1 did not. PPE1 enhanced IgE also in human memory B cells. Under Th1 conditions, Amb-APE did not influence immunoglobulin secretion. The IgE elevation was not ragweed specific. It correlated with proliferation of viable B cells, but not with IgE class switch. In vivo, Amb-APE increased total IgE and showed adjuvant activity in allergic airway inflammation.

CONCLUSIONS

Aqueous pollen extracts, the protein-free fraction of Amb-APE, and the pollen-contained substance PPE1 specifically enhance IgE production in Th2-primed B cells. Thus, pollen-derived nonallergenic substances might be responsible for B-cell-dependent aggravation of IgE-mediated allergies.

Pollen-derived adenosine is a necessary cofactor for ragweed allergy

BACKGROUND

Ragweed (Ambrosia artemisiifolia) is a strong elicitor of allergic airway inflammation with worldwide increasing prevalence. Various components of ragweed pollen are thought to play a role in the development of allergic responses. The aim of this study was to identify critical factors for allergenicity of ragweed pollen in a physiological model of allergic airway inflammation.

METHODS

Aqueous ragweed pollen extract, the low molecular weight fraction or the major allergen Amb a 1 was instilled intranasally on 1-11 consecutive days, and allergic airway inflammation was evaluated by bronchoalveolar lavage, lung histology, serology, gene expression in lung tissue, and measurement of lung function. Pollen-derived adenosine was removed from the extract enzymatically to analyze its role in ragweed-induced allergy. Migration of human neutrophils and eosinophils toward supernatants of ragweed-stimulated bronchial epithelial cells was analyzed.

RESULTS

Instillation of ragweed pollen extract, but not of the major allergen or the low molecular weight fraction, induced specific IgG1 , pulmonary infiltration with inflammatory cells, a Th2-associated cytokine signature in pulmonary tissue, and impaired lung function. Adenosine aggravated ragweed-induced allergic lung inflammation. In vitro, human neutrophils and eosinophils migrated toward supernatants of bronchial epithelial cells stimulated with ragweed extract only if adenosine was present.

CONCLUSIONS

Pollen-derived adenosine is a critical factor in ragweed-pollen-induced allergic airway inflammation. Future studies aim at therapeutic strategies to control these allergen-independent pathways.

The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures

The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization.

Memory and PTPIP51--a new protein in hippocampus and cerebellum

Previously the expression of Protein Tyrosine Phosphatase Interacting Protein 51 (PTPIP51) in mouse brain was reported. Here, we investigated PTPIP51 mRNA and protein in two of the brain regions namely the hippocampus and the cerebellum of mouse brains. On a cellular level both the protein and the mRNA were related to the pyramidal cells of the hippocampal formation, the granular cells of the dentate gyrus and the cells of the adjacent strata. In the cerebellum PTPIP51 was traced in Purkinje cells, the cells of the molecular layer and the granular layer. On a subcellular level only partial co-localization was seen for the endoplasmic reticulum, but not with mitochondria. In addition the interactome of PTPIP51 was analysed. In hippocampal cells a strong interaction with PTP1B and vesicle-associated membrane protein-associated protein B (VAPB) was detected. A somewhat differing interaction profile was found in the cerebellum, where high interaction levels were found for 14-3-3, diacylglycerol kinase α (DGKα), NFκB and PTP1B. These interaction partners represent specific signalling pathways linked to building memory. PTPIP51 can be associated with nerve growth factor signalling, dendritic and axonal growth, synaptogenesis, and all processes needed for memory formation. Moreover, in HT-22 mouse hippocampal cells PTPIP51 expression was induced by administrating the fibroblast growth factor 1 (FGF-1), which is known to take part in learning/memory processes. Knocking down p38-MAPK also led to an up-regulation of PTPIP51 probably resembling a compensative mechanism. Thus, a possible connection to the processing of memories can be anticipated. Differences in the interaction profile in both regions may be attributed to the actual/local differences in memory formation.

Improved upper limits on the stochastic gravitational-wave background from 2009-2010 LIGO and Virgo data

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Ω_{GW}(f)=Ω_{α}(f/f_{ref})^{α}, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of α=0, we constrain the energy density of the stochastic background to be Ω_{GW}(f)<5.6×10^{-6}. For the 600-1000 Hz band, Ω_{GW}(f)<0.14(f/900  Hz)^{3}, a factor of 2.5 lower than the best previously reported upper limits. We find Ω_{GW}(f)<1.8×10^{-4} using a spectral index of zero for 170-600 Hz and Ω_{GW}(f)<1.0(f/1300  Hz)^{3} for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Emergence of massless Dirac fermions in graphene's Hofstadter butterfly at switches of the quantum Hall phase connectivity

The fractal spectrum of magnetic minibands (Hofstadter butterfly), induced by the moiré superlattice of graphene on a hexagonal crystal substrate, is known to exhibit gapped Dirac cones. We show that the gap can be closed by slightly misaligning the substrate, producing a hierarchy of conical singularities (Dirac points) in the band structure at rational values Φ = (p/q)(h/e) of the magnetic flux per supercell. Each Dirac point signals a switch of the topological quantum number in the connected component of the quantum Hall phase diagram. Model calculations reveal the scale-invariant conductivity σ = 2qe(2)/πh and Klein tunneling associated with massless Dirac fermions at these connectivity switches.

Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

Wigner-Poisson statistics of topological transitions in a Josephson junction

The phase-dependent bound states (Andreev levels) of a Josephson junction can cross at the Fermi level if the superconducting ground state switches between even and odd fermion parity. The level crossing is topologically protected, in the absence of time-reversal and spin-rotation symmetry, irrespective of whether the superconductor itself is topologically trivial or not. We develop a statistical theory of these topological transitions in an N-mode quantum-dot Josephson junction by associating the Andreev level crossings with the real eigenvalues of a random non-Hermitian matrix. The number of topological transitions in a 2π phase interval scales as √[N], and their spacing distribution is a hybrid of the Wigner and Poisson distributions of random-matrix theory.

Feasibility of a multdisciplinary lung cancer videoconference between a peripheral hospital and a comprehensive cancer centre

OBJECTIVE

Treatment of lung cancer patients is changing rapidly and new treatment options have emerged in recent years. In 2007, to guarantee the best treatment procedure for lung cancer patients being treated in our peripheral hospital, we decided to introduce an interdisciplinary tumour videoconference between the Haemato-Oncological Day Hospital in Merano and the Comprehensive Cancer Centre Innsbruck. This retrospective analysis aims to describe the feasibility of such a conference.

PATIENTS AND METHODS

Two hundred and three patients with lung cancer treated at the peripheral hospital of Merano between May 2003 until May 2011 were retrospectively analysed. After introduction of the tumour videoconference in 2007, 54% (n = 110) of the patients in this cohort were discussed in the conference.

RESULTS

One hundred and four videoconferences were performed. Videoconference was feasible for 110 patients. Radiotherapeutic treatments were prescribed more frequently in patients from the conference group. Overall, major and minor treatment changes were undertaken in 7% (n = 8) and 18% (n = 20), respectively.

CONCLUSION

Interdisciplinary tumour videoconference is feasible between a peripheral hospital and a comprehensive cancer centre. Radiotherapeutic treatment was prescribed more frequently, suggesting that such a conference facilitates the access to cancer-centre-specific treatment modalities. Accordingly, tumour videoconference between a peripheral hospital and a cancer centre is to be recommend.

PTPIP51: a new interaction partner of the insulin receptor and PKA in adipose tissue

AIMS

Our previous experiments revealed an association of PTPIP51 (protein tyrosine phosphatase interacting protein 51) with the insulin signalling pathway through PTP1B and 14-3-3beta. We aimed to clarify the role of PTPIP51 in adipocyte metabolism.

METHODS

Four groups of ten C57Bl/6 mice each were used. Two groups were fed a standard diet; two groups were fed a high-fat diet. Two groups (one high-fat diet and one standard diet) were submitted to endurance training, while the remaining two groups served as untrained control groups. After ten weeks, we measured glucose tolerance of the mice. Adipose tissue samples were analyzed by immunofluorescence and Duolink proximity ligation assay to quantify interactions of PTPIP51 with either insulin receptor (IR) or PKA.

RESULTS

PTPIP51 and the IR and PTPIP51 and PKA, respectively, were colocalized in all groups. Standard diet animals that were submitted to endurance training showed low PTPIP51-IR and PTPIP51-PKA interactions. The interaction levels of both the IR and PKA differed between the feeding and training groups.

CONCLUSION

PTPIP51 might serve as a linking protein in adipocyte metabolism by connecting the IR-triggered lipogenesis with the PKA-dependent lipolysis. PTPIP51 interacts with both proteins, therefore being a potential gateway for the cooperation of both pathways.

PTPIP51, a positive modulator of the MAPK/Erk pathway, is upregulated in glioblastoma and interacts with 14-3-3β and PTP1B in situ

Glioblastoma multiforme (GBM) is the most common and most malignant primary brain tumour. Protein tyrosine phosphatase interacting protein 51 (PTPIP51) is an interaction partner of 14-3-3β, which correlates with the grade of malignancy in gliomas. In this study PTPIP51 and its interacting partners 14-3-3β, PTP1B, c-Src, Raf-1 as well as EGFR were investigated in human glioblastoma. Twenty glioblastoma samples were analyzed on transcriptional and translational level by immunohistochemistry, in situ hybridization and RT-PCR. To compare PTPIP51 expression in gliomas of different malignancies, quantitative RT-PCR for grade II astrocytoma and GBM samples was employed. Additionally, we analyzed the correlation between PTPIP51 and 14-3-3β transcription, and checked for in situ interaction between PTPIP51 and 14-3-3β and PTP1B, respectively. PTPIP51 and 14-3-3β mRNA showed a tumour grade dependent upregulation in gliomas. Glioblastoma cells displayed a strong immunoreaction of PTPIP51, which co-localized with 14-3-3β and PTP1B. The duolink proximity ligation assay corroborated a direct in situ interaction of PTPIP51 with both proteins, known to interact with PTPIP51 in vitro. The in vitro interacting partners Raf-1 and c-Src showed a partial co-localization. Besides, immune cells located in capillaries or infiltrating the tumour tissue and endothelial cells of pseudoglomerular vessels revealed a high PTPIP51 expression. The upregulation of PTPIP51 and its connection with the EGFR/MAPK pathway by 14-3-3β via Raf-1 and by PTP1B via c-Src, argue for a functional role of PTPIP51 in the pathogenesis of human glioblastoma.

[Refixation of distal biceps tendon rupture using 2 anchor sutures - sports ability after 1 year follow-up and operative technique]

BACKGROUND

Rupture of distal biceps tendon often occurs in physical active male persons between 30 and 50 years. The standard treatment consists of operative refixation of the ruptured tendon stump. In literature there are various methods described. Due to the high expectations of this group of patients, we examined the sports ability after 1 year follow-up and describe our employed operative fixation technique.

MATERIAL

Between 2004 and 2008 we treated 20 male persons in a prospective study with distal biceps tendon rupture. Applying the score of Rattanen and Orawa we evaluated the M. biceps force in flexion and supination and changes in the patients' sports activity. Furthermore we documented complications and the anchor localization via x-ray.

RESULTS

The score results varied between excellent in 14 patients and good and fair in 3 cases respectively. Using only 1 suture anchor (3 patients), either a knot or a wire failure appeared within 5 days. Anchor malpositions were discovered in 2 patients. The force measurement showed threetimes minor but in 3 patients major force deficits. Lack of extension or supination movement could be stated in 3 cases. Changes in their sports ability reported 8 persons. Of the remaining 12 patients, the original sports level was reached after 9 months.

CONCLUSION

Two anchors proved to guarantee a stable fixation of the distal biceps tendon stump. On the contrary we see the danger of fixation failure in using only 1 anchor. The best results achieved patients with a primer stable and correct located anchoring, therefore we recommend two anchors placed under radiological control. Regarding the score results, fixation of the distal biceps tendon is a demanding procedure, that should be performed by experienced surgeon.

Quantized conductance at the Majorana phase transition in a disordered superconducting wire

Superconducting wires without time-reversal and spin-rotation symmetries can be driven into a topological phase that supports Majorana bound states. Direct detection of these zero-energy states is complicated by the proliferation of low-lying excitations in a disordered multimode wire. We show that the phase transition itself is signaled by a quantized thermal conductance and electrical shot noise power, irrespective of the degree of disorder. In a ring geometry, the phase transition is signaled by a period doubling of the magnetoconductance oscillations. These signatures directly follow from the identification of the sign of the determinant of the reflection matrix as a topological quantum number.

PTPIP51 interaction with PTP1B and 14-3-3β in adipose tissue of insulin-resistant mice

OBJECTIVE

We investigated the expression of protein tyrosine phosphatase-interacting protein 51 (PTPIP51) and its interaction with protein tyrosine phosphatase 1B (PTP1B) and 14-3-3β in mice exhibiting insulin resistance and obesity.

DESIGN

A total of 20 mice were included in the study. Eight control animals were fed a normal standard diet, six animals were fed a high-fat diet and six animals were submitted to a treadmill training parallel to the feeding of a high-fat diet. After 10 weeks, a glucose tolerance test was performed and abdominal adipose tissue samples of the animals were collected.

RESULTS

PTPIP51 protein was identified in the adipocytes of all samples. PTPIP51 interacted with PTP1B and with 14-3-3β protein. Compared with untrained mice fed a standard diet, the interaction of PTPIP51 with PTP1B was reduced in high-fat diet-fed animals. The highest interaction of PTPIP51 with 14-3-3β was seen in trained animals on high-fat diet, whereas untrained animals on high-fat diet displayed lowest values.

CONCLUSION

PTPIP51 is expressed in adipose tissue of humans, rats and mice. Obesity with enhanced insulin resistance resulted in a reduction of PTPIP51 levels in adipocytes and influenced the interactions with PTP1B and 14-3-3β. The interaction of PTPIP51 with PTP1B suggests a regulatory function of PTPIP51 in insulin receptor signal transduction. The interaction of PTPIP51 with 14-3-3β, especially in trained individuals, hints to an involvement of PTPIP51 in the downstream regulation of insulin action.

Majorana bound states without vortices in topological superconductors with electrostatic defects

Vortices in two-dimensional superconductors with broken time-reversal and spin-rotation symmetry can bind states at zero excitation energy. These so-called Majorana bound states transform a thermal insulator into a thermal metal and may be used to encode topologically protected qubits. We identify an alternative mechanism for the formation of Majorana bound states, akin to the way in which Shockley states are formed on metal surfaces: An electrostatic line defect can have a pair of Majorana bound states at the end points. The Shockley mechanism explains the appearance of a thermal metal in vortex-free lattice models of chiral p-wave superconductors and (unlike the vortex mechanism) is also operative in the topologically trivial phase.

Expression profile of PTPIP51 in mouse brain

This study demonstrates the expression of the novel protein protein tyrosine phophatase-interacting protein 51 (PTPIP51) in mammalian brain tissue. Serial sections of the whole adult mouse brain were analyzed for PTPIP51 protein and mRNA by immunohistochemistry, immunoblotting, RT-PCR, and in situ hybridization. Recent investigations by Yu et al. (2008) describe PTPIP51 as being capable of activating Raf-1, thereby modulating the MAPK pathway. The role of Raf-1, as well as of 14-3-3, in neurological disorders is well established. PTPIP51 expression was confined to neurons in the following structures: the piriform cortex and their connections to the anterior commissure, nucleus accumbens, paraventricular and supraoptical nuclei, neurohypophysis, superior colliculus, genu of facialis nerve, spinal trigeminal tract, inferior cerebellar peduncle, and cerebellum. In the cerebellum, a subpopulation of Purkinje cells and their dendrites was strongly PTPIP51 positive. Moreover, PTPIP51 was found to be colocalized with vasopressin and its transport protein neurophysin II in the neuroendocrine nuclei and their connections to the neurohypophysis. The data presented here suggest a role of PTPIP51 in neuronal homeostasis, axonal growth, and transport.

Theory of the topological anderson insulator

We present an effective medium theory that explains the disorder-induced transition into a phase of quantized conductance, discovered in computer simulations of HgTe quantum wells. It is the combination of a random potential and quadratic corrections proportional to p2 sigma(z) to the Dirac Hamiltonian that can drive an ordinary band insulator into a topological insulator (having an inverted band gap). We calculate the location of the phase boundary at weak disorder and show that it corresponds to the crossing of a band edge rather than a mobility edge. Our mechanism for the formation of a topological Anderson insulator is generic, and would apply as well to three-dimensional semiconductors with strong spin-orbit coupling.

The novel protein PTPIP51 is expressed in human keratinocyte carcinomas and their surrounding stroma

Background: The novel protein PTPIP51 (SwissProt accession code Q96SD6) is known to interact with two non-transmembrane protein-tyrosine phosphatases, PTP1B and TCPTP in vitro. Overexpression of the full-length protein induces apoptosis in HeLa and HEK293T cells (Lv et al. 2006). PTPIP51 shows a tissue-specific expression pattern and is associated with cellular differentiation and apoptosis in some mammalian tissues, especially in human follicular and interfollicular epidermis. PTPIP51 protein is expressed in all suprabasal layers of normal epidermis, whereas the basal layer contains PTPIP51 mRNA only but lacks the protein. Objectives: The expression of PTPIP51 was investigated in keratinocyte carcinomas, that is human basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) as well as Bowen's disease (BD) and keratoacanthomas (KAs) on a transcriptional (mRNA) and translational (immunohistochemical) level. Methods: Formalin-fixed, paraffin-embedded sections of BCCs, SCCs, KAs and BD, respectively, were analysed by RT-PCR, as well as immunohistochemistry and subsequent fluorescence microscopy. PTPIP51-positive cells of the tumour and the surrounding stroma were identified on the basis of specific morphological features by means of H & E staining. To obtain further information about a putative function of PTPIP51, a possible association of PTPIP51 with apoptotic cells, as well as an assumed negative correlation with proliferating cells was investigated by means of an in-situ TUNEL assay and Ki67/MIB-1 antigen staining, respectively. Co-immunostainings with PTPIP51 were performed for the following antigens: TCPTP, PTP1B and β-catenin. Results: PTPIP51-expression was detected in BCCs and SCCs of the skin, as well as in KAs and BD. Both types of keratinocyte carcinoma revealed a specific localization pattern of PTPIP51 in malignant keratinocytes. Whereas PTPIP51 -positive cells of BCC were found to form two cluster types with a different subcellular localization of the protein, i.e. cytoplasmic and nuclear or predominantly membranous, investigation of SCC revealed a meshwork-like appearance of PTPIP51-positive malignant keratinocytes, created by a mainly membranous localization. BD and KA resembled the findings of PTPIP51-expression in SCC. Furthermore, we observed a partial co-localization of PTP1B and PTPIP51 in BCC. SCC and BCC showed a co-expression and partial co-localization of PTPIP51 with β-catenin. Some PTPIP51-positive cells were found to undergo apoptosis. PTPIP51 was also expressed in cells comprising the surrounding stromal microenvironment. This was particularly noticed for endothelial cells lining peritumoural vessels as well as for infiltrating cells of both, the innate and the adaptive immune system. Conclusions: The results showed a distinct mainly membranous expression pattern of PTPIP51 in BCCs and SCCs. Since PTPIP51 was also detected in the peritumoural tissue, the protein may play a crucial role in keratinocyte tumour development.

Microphotometric determination of enzyme activities in cryostat sections by the gel film technique

Use of the gel film technique in microphotometric determinations of enzyme activity is described. The microscope photometer is computer-controlled. It is programmed to deal with repetitive measurements at up to 12 selected positions within a tissue section and to evaluate recorded reaction rates statistically. Films of polyacrylamide gel with entrapped glucose-6-phosphate dehydrogenase are used as a model to demonstrate the correlation between local enzyme activity and the microphotometrically determined reaction rate. Enzyme activities at different positions in the same tissue section are determined and compared. Activity profiles of five enzymes (glutamate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, NAD-dependent tetrazolium reductase) in the liver are presented and show non-uniform intra-acinar distribution patterns. These results are interpreted in the light of the metabolic zonation of the hepatic acinus. Further applications of the method are discussed.

Elevations of FosB in the nucleus accumbens during forced cocaine abstinence correlate with divergent changes in reward function

Dysregulation of hedonic processing, in which seeking of drug reward becomes more desirable than seeking natural rewards, like food, sex, and novelty, is a consequence of chronic drug exposure and potentially leads to escalating drug usage and addiction. Here, we investigated the effects of chronic cocaine treatment (10 days of escalating doses of cocaine, 10-30 mg/kg) and multiple forced abstinence periods (2, 3 or 5 weeks) on the acute rewarding properties of either cocaine (10 mg/kg) or novel-objects using the conditioned place preference procedure. Following all cocaine withdrawal periods, cocaine preference was significantly elevated while novel object preference was abolished compared with saline-treated rats. At the earliest withdrawal period, these behavioral changes were accompanied by elevations in FosB-like immunoreactive staining in the basolateral amygdala (BLA) and nucleus accumbens shell (NAc-Sh) and core (NAc-C). FosB staining in all three brain areas correlated positively with cocaine preference, but negatively with novelty preference. After 5 weeks of withdrawal, FosB staining was only elevated in the NAc-Sh and again correlated positively with elevated cocaine preference but negatively with decreased novelty preference. These data indicate that alterations in the expression of FosB-like transcription factors in the NAc can predict the dysregulation of hedonic processing that occurs during protracted withdrawal from cocaine.

Orientation of the acetabular component

We compared the orientation of the acetabular component obtained by a conventional manual technique with that using five different navigation systems.

Three surgeons carried out five implantations of an acetabular component with each navigation system, as well as manually, using an anatomical model. The orientation of the acetabular component, including inclination and anteversion, and its position was determined using a co-ordinate measuring machine.

The variation of the orientation of the acetabular component was higher in the conventional group compared with the navigated group. One experienced surgeon took significantly less time for the procedure. However, his placement of the component was no better than that of the less experienced surgeons. Significantly better inclination and anteversion (p < 0.001 for both) were obtained using navigation. These parameters were not significantly different between the surgeons when using the conventional technique (p = 0.966).

The use of computer navigation helps a surgeon to orientate the acetabular component with less variation regarding inclination and anteversion.