Anti-angiotensin type 1 receptor antibodies associated with antibody-mediated rejection in patients without preformed HLA-donor-specific antibody

INTRODUCTION

Angiotensin II is a peptide hormone involved in the renin-angiotensin system (RAS). Anti-angiotensin receptor 1 (AT1R) antibodies are implicated in stimulating RAS and are suspected to have some adverse impacts on renal transplantation outcome.

METHODS

From November 2009 to February 2012, 37 remaining sera from renal transplantation recipients with biopsy-proven antibody-mediated rejection (AMR) (n = 6), acute cellular rejection (ACR) (n = 23), and AMR + ACR (n = 8) without preformed human leukocyte antigeon (HLA) antibodies were tested with anti-AT1R antibody assay. Forty-two control patients without rejection also were analyzed.

RESULTS

The frequency of elevated anti-AT1R antibodies was higher in patients with AMR (n = 14) compared to controls (28.6% vs 4.9%, P = .03, OR = 8.0). It was also higher in patients with AMR + ACR (n=8) (37.5% vs 4.9%, P = .03, OR = 12.0). There was no difference in frequencies of elevated anti-AT1R antibody in patients with ACR.

CONCLUSION

Anti-AT1R antibodies were suspected to be associated with occurrence of AMR without preformed HLA antibodies in renal transplantation. Further studies in a larger number of patients are needed.

Evaluation of anti-acne properties of phloretin in vitro and in vivo

OBJECTIVE

This study aimed to investigate the anti-acne properties of phloretin in vitro and in vivo.

METHODS

Anti-microbial activity against Propionibacterium acnes (P. acnes), Propionibacterium granulosum (P. granulosum) and Staphylococcus epidermidis (S. epidermidis) were observed by the minimum inhibitory concentration (MIC) and disc diffusion methods. The anti-inflammatory effects were studied in HaCaT cells based on P. acnes-induced inflammatory mediators, including PGE2 and COX-2, examined through enzyme-linked immunosorbent assay (ELISA) and luciferase reporter gene assay. Thirty healthy subjects with whiteheads participated in the clinical study. Comedo counting, and the amount of sebum and porphyrin were measured before treatment and following 4 consecutive weeks of treatment with phloretin.

RESULTS

Phloretin showed anti-microbial activities against P. acnes, P. granulosum, S. epidermidis with the MIC of 0.5, 0.5 and 0.25 mg mL(-1) , respectively. P. acnes-induced activation of the COX-2 promoter was markedly attenuated by phloretin treatment. Consistent with these results, inhibition of PGE2 production was also observed. In 1-month, placebo-controlled trials, phloretin showed clinically and statistically significant reduction of comedo counts and sebum output level. Compared to before treatment, whiteheads, blackheads, papules, sebum output level and amount of sebum and porphyrin were significantly decreased at 4 weeks in the test group.

CONCLUSIONS

This study revealed that phloretin inhibits the growth of P. acnes, P. granulosum, and S. epidermidis. In addition, we demonstrated that phloretin attenuates COX-2 and PGE2 expression during the P. acnes-induced upregulation of inflammatory signalling. Clinical studies further suggested that treatment with formulations containing phloretin confers anti-acne benefits. Based on these results, we suggest that phloretin may be introduced as a possible acne-mitigating agent.

Ultrafast spin-switching of a ferrimagnetic alloy at room temperature traced by resonant magneto-optical Kerr effect using a seeded free electron laser

Ultrafast magnetization reversal of a ferrimagnetic metallic alloy GdFeCo was investigated by time-resolved resonant magneto-optical Kerr effect measurements using a seeded free electron laser. The GdFeCo alloy was pumped by a linearly polarized optical laser pulse, and the following temporal evolution of the magnetization of Fe in GdFeCo was element-selectively traced by a probe free electron laser pulse with a photon energy tuned to the Fe M-edge. The results have been measured using rotating analyzer ellipsometry method and confirmed magnetization switching caused by ultrafast heating.

Point nodes persisting far beyond Tc in Bi2212

In contrast to a complex feature of antinodal state, suffering from competing orders, the pairing gap of cuprates is obtained in the nodal region, which therefore holds the key to the superconducting mechanism. One of the biggest question is whether the point nodal state as a hallmark of d-wave pairing collapses at T_c like the BCS-type superconductors, or it instead survives above T_c turning into the preformed pair state. A difficulty in this issue comes from the small magnitude of the nodal gap, which has been preventing experimentalists from solving it. Here we use a laser ARPES capable of ultrahigh-energy resolution, and detect the point nodes surviving far beyond T_c in Bi2212. By tracking the temperature evolution of spectra, we reveal that the superconductivity occurs when the pair-breaking rate is suppressed smaller than the single-particle scattering rate on cooling, which governs the value of T_c in cuprates.

The pairing gap of the high-T_c cuprates has been expected to close at the transition temperature, similarly to the case of conventional superconductors. Here the authors perform ARPES measurements on Bi2212, and reveal a point nodal gap formation beyond T_c, characterized in terms of three parameters.

Anisotropy of the superconducting gap in the iron-based superconductor BaFe2(As(1-x)P(x))2

We report peculiar momentum-dependent anisotropy in the superconducting gap observed by angle-resolved photoemission spectroscopy in BaFe₂(As_1-xP_x)₂ (x = 0.30, T_c = 30 K). Strongly anisotropic gap has been found only in the electron Fermi surface while the gap on the entire hole Fermi surfaces are nearly isotropic. These results are inconsistent with horizontal nodes but are consistent with modified s_± gap with nodal loops. We have shown that the complicated gap modulation can be theoretically reproduced by considering both spin and orbital fluctuations.

A transverse bunch by bunch feedback system for Pohang Light Source upgrade

The Pohang Light Source upgrade (PLS-II) project has successfully upgraded the Pohang Light Source (PLS). The main goals of the PLS-II project are to increase the beam energy to 3 GeV, increase the number of insertion devices by a factor of two (20 IDs), increase the beam current to 400 mA, and at the same time reduce the beam emittance to below 10 nm by using the existing PLS tunnel and injection system. Among 20 insertion devices, 10 narrow gap in-vacuum undulators are in operation now and two more in-vacuum undulators are to be installed later. Since these narrow gap in-vacuum undulators are most likely to produce coupled bunch instability by the resistive wall impedance and limit the stored beam current, a bunch by bunch feedback system is implemented to suppress coupled bunch instability in the PLS-II. This paper describes the scheme and performance of the PLS-II bunch by bunch feedback system.

Time-resolved photoemission apparatus achieving sub-20-meV energy resolution and high stability

The paper describes a time- and angle-resolved photoemission apparatus consisting of a hemispherical analyzer and a pulsed laser source. We demonstrate 1.48-eV pump and 5.92-eV probe measurements at the ⩾10.5-meV and ⩾240-fs resolutions by use of fairly monochromatic 170-fs pulses delivered from a regeneratively amplified Ti:sapphire laser system operating typically at 250 kHz. The apparatus is capable to resolve the optically filled superconducting peak in the unoccupied states of a cuprate superconductor, Bi2Sr2CaCu2O(8 + δ). A dataset recorded on Bi(111) surface is also presented. Technical descriptions include the followings: A simple procedure to fine-tune the spatio-temporal overlap of the pump-and-probe beams and their diameters; achieving a long-term stability of the system that enables a normalization-free dataset acquisition; changing the repetition rate by utilizing acoustic optical modulator and frequency-division circuit.

Dynamic transcription factor activity and networks during ErbB2 breast oncogenesis and targeted therapy

Tissue development and disease progression are multi-stage processes controlled by an evolving set of key regulatory factors, and identifying these factors necessitates a dynamic analysis spanning relevant time scales. Current omics approaches depend on incomplete biological databases to identify critical cellular processes. Herein, we present TRACER (TRanscriptional Activity CEll aRrays), which was employed to quantify the dynamic activity of numerous transcription factor (TFs) simultaneously in 3D and networks for TRACER (NTRACER), a computational algorithm that allows for cellular rewiring to establish dynamic regulatory networks based on activity of TF reporter constructs. We identified major hubs at various stages of culture associated with normal and abnormal tissue growth (i.e., ELK-1 and E2F1, respectively) and the mechanism of action for a targeted therapeutic, lapatinib, through GATA-1, which were confirmed in human ErbB2 positive breast cancer patients and human ErbB2 positive breast cancer cell lines that were either sensitive or resistant to lapatinib.

Docosahexaenoic acid induces the degradation of HPV E6/E7 oncoproteins by activating the ubiquitin-proteasome system

The oncogenic human papillomavirus (HPV) E6/E7 proteins are essential for the onset and maintenance of HPV-associated malignancies. Here, we report that activation of the cellular ubiquitin–proteasome system (UPS) by the omega-3 fatty acid, docosahexaenoic acid (DHA), leads to proteasome-mediated degradation of E6/E7 viral proteins and the induction of apoptosis in HPV-infected cancer cells. The increases in UPS activity and degradation of E6/E7 oncoproteins were associated with DHA-induced overproduction of mitochondrial reactive oxygen species (ROS). Exogenous oxidative stress and pharmacological induction of mitochondrial ROS showed effects similar to those of DHA, and inhibition of ROS production abolished UPS activation, E6/E7 viral protein destabilization, and apoptosis. These findings identify a novel role for DHA in the regulation of UPS and viral proteins, and provide evidence for the use of DHA as a mechanistically unique anticancer agent for the chemoprevention and treatment of HPV-associated tumors.

A fruit, milk and whole grain dietary pattern is positively associated with bone mineral density in Korean healthy adults

BACKGROUND/OBJECTIVES

Osteoporosis is a major health problem that will grow in burden with ageing of the global population. Modifiable risk factors for osteoporosis, including diet, have significant implications for disease prevention. We examined associations between dietary patterns and bone mineral density (BMD) in a Korean adult population.

SUBJECTS/METHODS

In total, 1828 individuals from the Healthy Twin Cohort were included as subjects. Information on general characteristics, lifestyles and health status was obtained through a health examination, and BMD was assessed using DEXA. Dietary intake was assessed using a 3-day food record, and dietary patterns were examined by factor analysis. Associations between dietary patterns and BMD were examined using mixed linear regression, adjusting for family and twin structure as well as other potential risk factors for bone health.

RESULTS

Four dietary patterns were identified (Rice and kimchi; eggs, meat and flour; Fruit, milk and whole grains; and Fast food and soda). The 'Fruit, milk and whole grains' pattern was associated with a reduced risk of having low BMD in men (odds ratio (OR)=0.38; 95% confidence interval (CI)=0.22-0.67) and women (OR=0.45; 95% CI=0.28-0.72) and was positively associated with BMD at multiple sites. The 'rice and kimchi' pattern had a positive association with only whole-arm BMD in men and women.

CONCLUSIONS

Our results suggest that a dietary pattern with high intake of dairy products, fruits and whole grains may contribute positively to bone health in a Korean adult population, and dietary pattern-based strategies could have potential in promoting bone health.

A fall prevention guideline for older adults living in long-term care facilities

BACKGROUND

Falls are among the most frequent critical health problems for older adults over 65 years of age and often result in consequential injuries.

AIM

This study developed a guideline covering risk factors and interventions for falls in order to prevent them from occurring in long-term care facilities.

METHODS

This study was grounded in the methodological approach of the Scottish Intercollegiate Guideline Network for establishing evidence-based guidelines: (1) establishment of the target population and scope of the guideline, (2) systematic literature review and critical analysis, (3) determination of the recommendation grade, (4) development of a draft nursing intervention guideline and algorithm, (5) expert evaluation of the draft nursing intervention guideline, and (6) confirmation of the final intervention guideline and completion of the algorithm.

RESULTS

The resulting evidence-based fall prevention guideline consists of a three-step factor assessment and a three-step intervention approach.

LIMITATIONS

The resulting guideline was based on the literature and clinical experts. Further research is required to test the guideline's feasibility in across long term care facilities.

CONCLUSION

This guideline can be used by nurses to screen patients who are at a high risk of falling to provide patient interventions to help prevent falls.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

Considering the high rate of falls at long-term care facilities and the absence of evidence-based guidelines to prevent them, additional studies on falls at long-term care facilities are necessary. Meanwhile, given prior research that indicates the importance of human resources in the application of such guidelines, continuous investigations are needed as to whether the research outcomes are actually conveyed to nurses.

Estimation of size of cord blood inventory based on high-resolution typing of HLAs

Methods for estimating the cord blood (CB) inventory size required vary according to the ethnic diversity of the HLA, degree of HLA matching and HLA-typing resolution. We estimated the CB inventory size required using 7190 stored CB units (CBU) and 2450 patients who were awaiting or underwent allogeneic hematopoietic stem cell transplantation. With high-resolution typing of HLA-A, B and DRB1, 94.6% of Korean patients could find CBUs in 100 000 CBUs with a 5/6 match, and 95.7% could find CBUs in 5000 CBUs with a 4/6 match. With low-resolution typing of HLA-A and B and high-resolution typing of leukocyte antigen-DRB1, 95% of patients could find CBUs in 50 000 CBUs with a 5/6 match, and 96.7% could find CBUs in 3000 CBUs  with a 4/6 match. With additional high-resolution typing for HLA-A and B, which could improve transplantation outcome, the size of the CB inventory would need to increase twofold for Koreans.

The effectiveness of a brochure describing an acceptable method of sputum collection for tuberculosis testing

We evaluated the effectiveness of an educational brochure explaining proper sputum collection techniques for tuberculosis (TB) diagnosis. Patients with suspected pulmonary TB (PTB) were randomly assigned to either the brochure-using group or the non-using group. No significant difference in positive TB culture rates was observed between the brochure-using and non-using groups (33.1% vs. 35.6%, P = 0.690). The proportions of acceptable specimen samples for bacterial pneumonia were also similar between the two groups (37.1% vs. 35.6%). An educational brochure provided by the attending physician explaining an acceptable specimen collection method for TB testing did not result in a higher detection rate of PTB.

Observation of quadrupole helix chirality and its domain structure in DyFe3(BO3)4

Resonant X-ray diffraction (RXD) uses X-rays in the vicinity of a specific atomic absorption edge and is a powerful technique for studying symmetry breaking by motifs of various multipole moments, such as electric monopoles (charge), magnetic dipoles (spin) and electric quadrupoles (orbital). Using circularly polarized X-rays, this technique has been developed to verify symmetry breaking effects arising from chirality, the asymmetry of an object upon its mirroring. Chirality plays a crucial role in the emergence of functionalities such as optical rotatory power and multiferroicity. Here we apply spatially resolved RXD to reveal the helix chirality of Dy 4f electric quadrupole orientations and its domain structure in DyFe3(BO3)4, which shows a reversible phase transition into an enantiomorphic space-group pair. The present study provides evidence for a helix chiral motif of quadrupole moments developed in crystallographic helix chirality.

Top-up operation at Pohang Light Source-II

After three years of upgrading work, PLS-II (S. Shin, Commissioning of the PLS-II, JINST, January 2013) is now successfully operating. The top-up operation of the 3 GeV linear accelerator had to be delayed because of some challenges encountered, and PLS-II was run in decay mode at the beginning in March 2012. The main difficulties encountered in the top-up operation of PLS-II are different levels between the linear accelerator and the storage ring, the 14 narrow gap in-vacuum undulators in operation, and the full energy injection by 3 GeV linear accelerator. Large vertical emittance and energy jitter of the linac were the major obstacles that called for careful control of injected beam to reduce beam loss in the storage ring during injection. The following measures were taken to resolve these problems: (1) The high resolution Libera BPM (see http://www.i-tech.si) was implemented to measure the beam trajectory and energy. (2) Three slit systems were installed to filter the beam edge. (3) De-Qing circuit was applied to the modulator system to improve the energy stability of injected beam. As a result, the radiation by beam loss during injection is reduced drastically, and the top-up mode has been successfully operating since 19th March 2013. In this paper, we describe the experimental results of the PLS-II top-up operation and the improvement plan.

Ahnak functions as a tumor suppressor via modulation of TGFβ/Smad signaling pathway

We provide detailed mechanisms of Ahnak-mediated potentiation of transforming growth factor β (TGFβ) signaling, which leads to a negative regulation of cell growth. We show that Smad3 interacts with Ahnak through MH2 domain and that Ahnak stimulates Smad3 localization into nucleus leading to potentiating TGFβ-induced transcriptional activity of R-Smad. Moreover, overexpression of Ahnak resulted in growth retardation and cell cycle arrest through downregulation of c-Myc and cyclin D1/D2. We describe results from analyses of Ahnak^−/− mouse model expressing middle T antigen in a mammary gland-specific manner (MMTV^Tg/+Ahnak^−/−), which showed significantly progressed hyperplasia of mammary glands compared with MMTV^Tg/+Ahnak^+/+. Finally, we screened multiple human breast cancer tissues and showed that the expression of Ahnak in cancer tissues is lower than that in control tissues by 50%. Taken together, these data indicate that Ahnak mediates a negative regulation of cell growth and acts as novel tumor suppressor through potentiation of TGFβ signaling.

Lentivirus delivery of IL-10 to promote and sustain macrophage polarization towards an anti-inflammatory phenotype

Gene delivery from biomaterials can create an environment that promotes and guides tissue formation. However, the immune response induced upon biomaterial implantation can be detrimental to tissue regeneration. Macrophages play a central role in mediating early phases of this response, and functional "polarization" of macrophages towards M1 (inflammatory) or M2 (anti-inflammatory) phenotypes may bias the local immune state at the implant site. Since gene delivery from biomaterial scaffolds can confer transgene expression in macrophages in vivo, we investigated whether transduction of macrophages with an IL-10 encoding lentivirus can (1) induce macrophage polarization toward an M2 phenotype even in an pro-inflammatory environment, and (2) prevent a shift in polarization from M2 to M1 following exposure to pro-inflammatory stimuli. IL-10 lentivirus delivery to pre-polarized M1 macrophages reduced TNF-α production 1.5-fold when compared to cells treated with either a control virus or a bolus delivery of recombinant IL-10 protein. IL-10 lentivirus delivery to naïve macrophages reduced the amount of TNF-α produced following an inflammatory challenge by 2.5-fold compared to cells treated with both the control virus and recombinant IL-10. At a mechanistic level, IL-10 lentivirus delivery mediated sustained reduction in NF-κB activation and, accordingly, reduced transcription of TNF-α. In sum, lentiviral delivery of IL-10 to macrophages represents a promising strategy for directing and sustaining macrophage polarization towards an M2 phenotype in order to promote local immune responses that facilitate tissue engineering.

Quality of functional haematopoietic stem/progenitor cells from cryopreserved human umbilical cord blood

BACKGROUND AND OBJECTIVES

Transplantation of cryopreserved umbilical cord blood (UCB) can be used to treat a multitude of haematologic and immunological diseases. In this study, we examined the quality of UCB cryopreserved for 2 (group I), 4 (group II) and 6 (group III) years.

METHODS

The following parameters and procedures were used to test individual units of cryopreserved UCB: the number of total nucleated cells (TNC), cell viability, CFU-GM assay, T-cell activation in vitro and haematopoietic stem cell engraftment in NOD/SCID mice in vivo.

RESULTS

The TNC recovery rates for groups I, II and III were 106·2 ± 6·17%, 96·69 ± 6·39% and 100·38 ± 5·27%, respectively, and the mean percentages of viable cells after thawing were 86·88%, 86·38% and 87·43%. When TNC were plated at 5 × 10(3), the number of CFU-GM was 13·6 (group I), 13·8 (group II), 14·2 (group III) and 14·7 (fresh UCB). We confirmed that the huCD4(+) and huCD8(+) T cells within cryopreserved UCB are functionally responsive by assessment of activated huCD25(+) cells. Moreover, the percentage of huCD45(+) cells in the bone marrow was 4·32 ± 1·29% (group I), 4·48 ± 1·11% (group II), 4·40% ± 1·12% (group III) and 4·50% ± 0·66% (fresh UCB), and that in the peripheral blood was 14·69 ± 3·08% (group I), 15·24 ± 4·05% (group II), 15·74 ± 3·43% (group III) and 17·48 ± 3·74% (fresh UCB) in NOD/SCID mice infused with isolated huCD34(+) cells.

CONCLUSION

These results indicated that cryopreserved UCB units efficiently retrieve in functionally competent form and are suitable for transplantation.

Bacillus anthracis lethal toxin induces cell-type-specific cytotoxicity in human lung cell lines

AIMS

Inhalational anthrax is caused by the entry of Bacillus anthracis spores into the lung. Inhaled spores are phagocytosed by alveolar macrophages. Bacilli then escape from the macrophage and spread to other cells, initiating a systemic anthrax infection. Based on the pathological studies of primate and human inhalational anthrax cases, it appears that lung tissue injury is a lethal consequence of the disease. Although the cytotoxicity of anthrax lethal toxin to macrophages is well known, it is not clear how anthrax toxin affects the various lung cell types.

METHODS AND RESULTS

Using model cell lines representing different physiological compartments of the lung, we have investigated the cytotoxic effects of anthrax lethal toxin. The cell response was evaluated through MTT metabolism, neutral red uptake, initiation of apoptosis, and expression and binding activity of anthrax toxin receptors. We found that a human small airway epithelial cell line, HSAEC, was susceptible to anthrax lethal toxin. The other cell lines, A549, MRC-5, H358 and SKLU-1, displayed resistance to anthrax lethal toxin-mediated toxicity, although the expression of anthrax toxin receptors was detected in all the cell lines tested.

CONCLUSIONS

Our results indicate that cell-type-specific toxicity may be induced by anthrax lethal toxin in human lung tissues and does not correlate with anthrax toxin receptor expression levels.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work suggests that cell-type-specific cytotoxicity of anthrax toxin in lung cells may cause subsequent lung disease progression. It may explain the initial pathogenic step of inhalational anthrax.

Relationship between socioeconomic status and anemia prevalence in adolescent girls based on the fourth and fifth Korea National Health and Nutrition Examination Surveys

BACKGROUND/OBJECTIVES

We studied the relationship between socioeconomic status (SES), represented by household income, and the prevalence of anemia and iron deficiency anemia (IDA) among adolescent girls in Korea.

SUBJECTS/METHODS

The samples were based on the data from a four-year (2008-2011) collection for the Korea National Health and Nutrition Examination Survey (1312 girls, age 10-18 years). The survey included demographic, anthropometric, biochemical and nutritional parameters. A multiple regression analysis after adjusting for age, body mass index (BMI), red blood cell count, white blood cell count and red meat intake was performed. Anemia was defined as hemoglobin level lower than 11.5 g/dl for ages 10-11 years and 12.0 g/dl for ages 12-14 years. Iron deficiency was defined as serum ferritin level below 15 μg/l.

RESULTS

The prevalences of anemia and IDA in Korean girls were 5.3 and 4.2%, respectively. Girls with anemia were older, taller, weighed more, had higher BMI, had higher portion of menarche experience and consumed less red meat than girls without anemia. Girls with higher income had lower anemia prevalence and consumed more iron and vitamins. Logistic regression analysis showed a decreasing trend in anemia prevalence as household income increased. Correlation analysis demonstrated that there is a relationship between household income and serum hemoglobin and ferritin levels (P=0.003 and P=0.026, respectively).

CONCLUSIONS

Higher SES leads to lower prevalence of anemia and IDA in Korean adolescent girls. This may be due to the fact that higher SES individuals consume more iron and vitamin C.

Existence of orbital order and its fluctuation in superconducting Ba(Fe(1-x)Co(x))2As2 single crystals revealed by x-ray absorption spectroscopy

We performed temperature dependent x-ray linear dichroism (XLD) experiments on an iron pnictide system, Ba(Fe(1-x)Co(x))2As2 with x=0.00, 0.05, 0.08, and 0.10 to experimentally verify the existence of orbital ordering (OO). Substantial XLD was observed in polarization dependent x-ray absorption spectra of Fe L edges. By exploiting the difference in the temperature dependent behaviors, OO, and structure contributions to XLD could be clearly separated. The observed OO signal indicates different occupation numbers for d(yz) and d(zx) orbitals and supports the existence of ferro-OO. The results are also consistent with the theoretical prediction. Moreover, we find substantial OO signal well above the structural and magnetic transition temperatures, which suggests the existence of strong OO fluctuations up to high temperatures.

Anomalous dressing of Dirac fermions in the topological surface state of Bi2Se3, Bi2Te3, and Cu-doped Bi2Se3

Quasiparticle dynamics on the topological surface state of Bi(2(3), Bi(2)Te(3), and superconducting Cu(x)Bi(2)Se(3) are studied by 7 eV laser-based angle resolved photoemission spectroscopy. We find strong mode couplings in the Dirac-cone surface states at energies of ~3 and ~15-20 meV associated with an exceptionally large coupling constant λ of ~3, which is one of the strongest ever reported for any material. This result is compatible with the recent observation of a strong Kohn anomaly in the surface phonon dispersion of Bi(2)Se(3), but it appears that the theoretically proposed "spin-plasmon" excitations realized in helical metals are also playing an important role. Intriguingly, the ~3 meV mode coupling is found to be enhanced in the superconducting state of Cu(x)Bi(2)Se(3).

Anomalous doping variation of the nodal low-energy feature of superconducting (Bi,Pb)2(Sr,La)2CuO(6+δ) crystals revealed by laser-based angle-resolved photoemission spectroscopy

The nodal band dispersion in (Bi,Pb)(2)(Sr,La)(2)CuO(6+δ) (Bi2201) is investigated over a wide range of doping by using 7-eV laser-based angle-resolved photoemission spectroscopy. We find that the low-energy band renormalization ("kink"), recently discovered in Bi(2)Sr(2)CaCu(2)O(8+δ) (Bi2212), also occurs in Bi2201, but at a binding energy around half that in Bi2212. Surprisingly, the coupling energy dramatically increases with a decrease of carrier concentration, showing a sharp enhancement across the optimal doping. These properties (material and doping dependence of the coupling energy) demonstrate the significant correlation among the mode coupling, the energy gap close to the node, and the strong electron correlation. Our results suggest forward scattering arising from the interplay between the electrons and in-plane polarized acoustic phonon branch as the origin of the low-energy renormalization.