Copper metallization for current very large scale integration

As silicon technology scaling progresses to the 32 nm node or even further, the design on the propagation of electromagnetic signals becomes increasingly appealing due to their unyielding constraints on interconnect delay. Because of its high conductivity and electromigration resistance, Cu is now the interconnect materials in current VLSI. To ensure the signal propagation via the Cu interconnects upon the increasingly reduction in the interconnect width, related issues on Cu interconnects, such as electron scattering at surfaces and grain boundaries, electromigration failure and surface oxidation, still need to be further understood and addressed. Besides this, the performance of low-k dielectrics and reliable barrier structures, which are also much important among the device parts, are required to be further improved to minimize the signal delay and to prevent penetration of different materials, respectively. On the basis of the paper published at Recent Patent on Nanotechnology 2007; 1: 193-209, this review will focus on recent patents and some studies on Cu metallization including Cu interconnect wires, low-k dielectrics and related barrier materials as well as manufacturing techniques in VLSI, which are one of the most essential concerns in microelectronic industry and decide further development of VLSI. This review will benefit for the design of the Cu metallization in the current VLSI.

The role of electrical signals in murine corneal wound re-epithelialization

Ion flow from intact tissue into epithelial wound sites results in lateral electric currents that may represent a major driver of wound healing cell migration. Use of applied electric fields (EF) to promote wound healing is the basis of Medicare-approved electric stimulation therapy. This study investigated the roles for EFs in wound re-epithelialization, using the Pax6(+/-) mouse model of the human ocular surface abnormality aniridic keratopathy (in which wound healing and corneal epithelial cell migration are disrupted). Both wild-type (WT) and Pax6(+/-) corneal epithelial cells showed increased migration speeds in response to applied EFs in vitro. However, only Pax6(+/+) cells demonstrated consistent directional galvanotaxis towards the cathode, with activation of pSrc signaling, polarized to the leading edges of cells. In vivo, the epithelial wound site normally represents a cathode, but 43% of Pax6(+/-) corneas exhibited reversed endogenous wound-induced currents (the wound was an anode). These corneas healed at the same rate as WT. Surprisingly, epithelial migration did not correlate with direction or magnitude of endogenous currents for WT or mutant corneas. Furthermore, during healing in vivo, no polarization of pSrc was observed. We found little evidence that Src-dependent mechanisms of cell migration, observed in response to applied EFs in vitro, normally exist in vivo. It is concluded that endogenous EFs do not drive long-term directionality of sustained healing migration in this mouse corneal epithelial model. Ion flow from wounds may nevertheless represent an important component of wound signaling initiation.

Radiation-induced intercellular signaling mediated by cytochrome-c via a p53-dependent pathway in hepatoma cells

The tumor suppressor p53 has a crucial role in cellular response to DNA damage caused by ionizing radiation, but it is still unclear whether p53 can modulate radiation-induced bystander effects (RIBE). In the present work, three different hepatoma cell lines, namely HepG2 (wild p53), PLC/PRF/5 (mutation p53) and Hep3B (p53 null), were irradiated with γ-rays and then co-cultured with normal Chang liver cell (wild p53) in order to elucidate the mechanisms of RIBE. Results showed that the radiosensitivity of HepG2 cells was higher than that of PLC/PRF/5 and Hep3B cells. Only irradiated HepG2 cells, rather than irradiated PLC/PRF/5 or Hep3B cells, could induce bystander effect of micronuclei (MN) formation in the neighboring Chang liver cells. When HepG2 cells were treated with 20 μM pifithrin-α, an inhibitor of p53 function, or 5 μM cyclosporin A (CsA), an inhibitor of cytochrome-c release from mitochondria, the MN induction in bystander Chang liver cells was diminished. In fact, it was found that after irradiation, cytochrome-c was released from mitochondria into the cytoplasm only in HepG2 cells in a p53-dependent manner, but not in PLC/PRF/5 and Hep3B cells. Interestingly, when 50 μg/ml exogenous cytochrome-c was added into cell co-culture medium, RIBE was significantly triggered by irradiated PLC/PRF/5 and Hep3B cells, which previously failed to provoke a bystander effect. In addition, this exogenous cytochrome-c also partly recovered the RIBE induced by irradiated HepG2 cells even with CsA treatment. Our results provide new evidence that the RIBE can be modulated by the p53 status of irradiated hepatoma cells and that a p53-dependent release of cytochrome-c may be involved in the RIBE.

Irbesartan treatment up-regulates hepatic expression of PPARalpha and its target genes in obese Koletsky (fa(k)/fa(k)) rats: a link to amelioration of hypertriglyceridaemia

BACKGROUND AND PURPOSE

Hypertriglyceridaemia is associated with an increased risk of cardiovascular disease. Irbesartan, a well-established angiotensin II type 1 receptor (AT(1)) blocker, improves hypertriglyceridaemia in rodents and humans but the underlying mechanism of action is unclear.

EXPERIMENTAL APPROACH

Male obese Koletsky (fa(k)/fa(k)) rats, which exhibit spontaneous hypertension and metabolic abnormalities, received irbesartan (40 mg x kg(-1) x day(-1)) or vehicle by oral gavage over 7 weeks. Adipocyte-derived hormones in plasma were measured by ELISA. Gene expression in liver and other tissues was assessed by real-time PCR and Western immunoblotting.

KEY RESULTS

In Koletsky (fa(k)/fa(k)) rats irbesartan lowered plasma concentrations of triglycerides and non-esterified fatty acids, and decreased plasma insulin concentrations and the homeostasis model assessment of insulin resistance index. However, this treatment did not affect food intake, body weight, epididymal white adipose tissue weight, adipocyte size and plasma leptin concentrations, although plasma adiponectin was decreased. Irbesartan up-regulated hepatic expression of mRNAs corresponding to peroxisome proliferator-activated receptor (PPAR)alpha and its target genes (carnitine palmitoyltransferase-1a, acyl-CoA oxidase and fatty acid translocase/CD36) that mediate hepatic fatty acid uptake and oxidation; the increase in hepatic PPARalpha expression was confirmed at the protein level. In contrast, irbesartan did not affect expression of adipose PPARgamma and its downstream genes or hepatic genes that mediate fatty acid synthesis.

CONCLUSIONS AND IMPLICATIONS

These findings demonstrate that irbesartan treatment up-regulates PPARalpha and several target genes in liver of obese spontaneously hypertensive Koletsky (fa(k)/fa(k)) rats and offers a novel insight into the lipid-lowering mechanism of irbesartan.

Search for f(J)(2220) in radiative J/ψ decays

We present a search for f(J)(2220) production in radiative J/ψ→γf(J)(2220) decays using 460  fb⁻¹ of data collected with the BABAR detector at the SLAC PEP-II e(+)e⁻ collider. The f(J)(2220) is searched for in the decays to K(+)K⁻ and K(S)⁰K(S)⁰. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γf(J)(2220) and f(J)(2220)→K(+)K⁻(K(S)⁰K(S)⁰) as a function of spin and helicity are set at the level of 10⁻⁵, below the central values reported by the Mark III experiment.

The level of vascular endothelial cell growth factor, nitric oxide, and endothelin-1 was correlated with ovarian volume or antral follicle counts: a potential predictor of pregnancy outcome in IVF

The objective of this study was to investigate the correlation between the concentrations of vascular endothelial cell growth factor (VEGF), nitric oxide (NO), or endothelin-1 (ET-1) in follicular fluid with antral follicle counts (AFCs) or ovarian volume in order to predict the outcome of in vitro fertilization (IVF). One hundred and thirty-one patients were enrolled in this study, and the pregnancy rate was 37.4%. The concentration of VEGF or NO was significantly increased, while the concentration of ET-1 in follicular fluid was decreased in the group who became pregnant (P < 0.05). The ovarian volume or AFC was significantly higher in groups that became pregnant (P < 0.05). In addition, the ovarian volume or AFC was positively correlated with the concentration of VEGF or NO and negatively correlated with the concentration of ET-1 in follicular fluid. Our data suggest that these correlations may be associated with the successful pregnancies through IVF.

Evidence for direct CP violation in the measurement of the Cabbibo-Kobayashi-Maskawa angle γ with B∓ → D(*)K(*)∓ decays

We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle γ through a Dalitz plot analysis of neutral D-meson decays to K(S)(0) π+ π- and K(S)(0) K+ K- produced in the processes B∓ → DK∓, B∓ D* K∓ with D* → Dπ(0), Dγ, and B∓ → DK*∓ with K*∓ → K(S)(0) π∓, using 468 million BB pairs collected by the BABAR detector at the PEP-II asymmetric-energy e+ e- collider at SLAC. We measure γ = (68 ± 14 ± 4 ± 3)° (modulo 180°), where the first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with γ = 0 (no direct CP violation) with a significance of 3.5 standard deviations.

Ethyl acetate fraction of the root of Rubia cordifolia L. inhibits keratinocyte proliferation in vitro and promotes keratinocyte differentiation in vivo: potential application for psoriasis treatment

Psoriasis is a skin disease associated with hyperproliferation and aberrant differentiation of keratinocytes. Our previous studies have identified the root of Rubia cordifolia L. as a potent antiproliferative and apoptogenic agent in cultured HaCaT cells (IC(50) 1.4 microg/ml). In the present study, ethanolic extract of Radix Rubiae was fractioned sequentially with hexane, ethyl acetate (EA), n-butanol and water. EA fraction was found to possess most potent antiproliferative action on HaCaT cells (IC(50) 0.9 microg/ml). Mechanistic study revealed that EA fraction induced apoptosis on HaCaT cells, as it was capable of inducing apoptotic morphological changes. Annexin V-PI staining assay also demonstrated that EA fraction significantly augmented HaCaT apoptosis. In addition, EA fraction decreased mitochondrial membrane potential in a concentration- and time-dependent manner. The standardized EA fraction was formulated into topical gel and its keratinocyte-modulating action was tested on mouse tail model. EA fraction dose-dependently increased the number and thickness of granular layer and epidermal thickness on mouse tail skin, indicative of the keratinocyte differentiation-inducing activity. Taking the in vitro and in vivo findings together, the present preclinical study confirms that EA fraction is a promising antipsoriatic agent warranting further development for psoriasis treatment.

Abnormal DNA methylation in peripheral blood mononuclear cells from patients with vitiligo

BACKGROUND

Vitiligo is a skin disorder characterized by the destruction of melanocytes by autoreactive lymphocytes. The genetic and environmental factors that trigger the autoimmune response are poorly understood. However, alterations to epigenetic DNA methylation patterns contribute to many other autoimmune diseases.

OBJECTIVES

To investigate genomic and gene-specific DNA methylation levels in peripheral blood mononuclear cells (PBMCs) of patients with vitiligo and to relate any changes to the expression of genes that regulate methylation, as well as the autoimmune-related gene IL10.

METHODS

We quantified global methylcytosine levels in PBMCs from 20 patients with vitiligo and 20 healthy controls. mRNA levels of DNA methyltransferases (DNMTs), methyl-DNA binding domain proteins (MBDs) and interleukin (IL)-10 were measured by real-time reverse transcriptase-polymerase chain reaction. Methylation of an IL10 regulatory element domain was determined by bisulphite genomic sequencing.

RESULTS

Genomic DNA methylation in PBMCs of patients with vitiligo was increased relative to healthy controls (P = 0·012). DNMT1, MBD1, MBD3, MBD4 and MeCP2 expression was significantly higher than in control PBMCs (P = 0·013, 0·001, 0·005, 0·001 and 0·001, respectively). MBD1 and MBD3 expression correlated positively with global DNA methylation in vitiligo PBMCs (MBD1: r = 0·519, P = 0·019; MBD3: r = 0·529, P = 0·016). IL10 expression was significantly decreased (P = 0·030), and an IL-10 enhancer region was hypermethylated in vitiligo PBMCs compared with controls (P = 0·014).

CONCLUSIONS

These data show that levels of DNA methylation are altered in PBMCs of patients with vitiligo, and this may contribute to disease activity by affecting the expression of autoimmunity-related genes.

Measurement of D0-D0 mixing parameters using D0 → K(S)(0)π+ π- and D0 → K(S)(0)K+ K- decays

We report a direct measurement of D0-D0 mixing parameters through a time-dependent amplitude analysis of the Dalitz plots of D(0) → K(S)(0) π+ π- and, for the first time, D0 → K(S)(0)K+ K- decays. The low-momentum pion π(s)(+) in the decay D*+ → D0 π(s)(+) identifies the flavor of the neutral D meson at its production. Using 468.5 fb(-1) of e+ e- colliding-beam data recorded near square root(s)=10.6 GeV by the BABAR detector at the PEP-II asymmetric-energy collider at SLAC, we measure the mixing parameters x = [1.6 ± 2.3(stat) ± 1.2(syst) ± 0.8(model)] × 10(-3), and y = [5.7 ± 2.0(stat) ± 1.3(syst) ± 0.7(model)] × 10(-3). These results provide the best measurement to date of x and y. The knowledge of the value of x, in particular, is crucial for understanding the origin of mixing.

Angiotensin II type 1 receptor-independent beneficial effects of telmisartan on dietary-induced obesity, insulin resistance and fatty liver in mice

AIMS/HYPOTHESIS

Evidence suggests that telmisartan, an angiotensin II type 1 receptor (AT1) blocker and peroxisome proliferator-activated receptor-gamma partial agonist, has beneficial actions that limit development of the metabolic syndrome and diabetes. However, the role played by AT1 inhibition in metabolic effects elicited by telmisartan remains uncertain. Here we isolated the metabolic effects of telmisartan from AT1 antagonism.

METHODS

Male At1a (also known as Agtr1a)-deficient mice were fed a standard diet or 60% high-fat diet; those on high-fat diet were co-administered telmisartan (3 mg kg(-1) day(-1) by oral gavage) or vehicle for 12 weeks.

RESULTS

In At1a-null mice, telmisartan prevented high-fat-diet-induced increases in (1) body weight, epididymal and inguinal white adipose tissue weight, adipocyte size and plasma leptin concentration; (2) plasma glucose and insulin concentrations and HOMA index; and (3) liver weight and triacylglycerol content. Insulin tolerance testing also indicated that telmisartan improved the high-fat-diet-induced reduction of glucose-lowering by insulin.

CONCLUSIONS/INTERPRETATION

The present findings demonstrate beneficial, AT1-independent effects of the AT1 blocker telmisartan on dietary-induced obesity, insulin resistance and fatty liver in animals.

Ultrabroadband optical circular polarizers consisting of double-helical nanowire structures

Recently, it was demonstrated by Gansel et al. [Science 325, 1513 (2009)] that 3D single-helical metamaterials can serve as broadband circular polarizers in the IR range. In this study, we propose a structured metamaterial with double-helical nanowires to construct circular polarizers with boarder wavelength bands in the visible-light and near-IR regions. Using the finite-difference time-domain method, we confirmed that the circular polarizers with the double-helical structures have operation bands more than 50% broader than those of the single-helical structures.

Measurements of charged current lepton universality and |Vus| using tau lepton decays to e- ν(e) ν(τ), μ- ν(μ) ν(τ), π- ν(τ), and K- ν(τ)

Using 467  fb(-1) of e+e- annihilation data collected with the BABAR detector, we measure (B(τ- → μ- ν(μ) ν(τ)))/(B(τ- → e- ν(e) ν(τ))) =(0.9796±0.0016±0.0036), (B(τ- → π- ν(τ)))/(B(τ- → e- ν(e) ν(τ))) = (0.5945±0.0014±0.0061), and (B(τ- → K- ν(τ)))/(B(τ- → e- ν(e) ν(τ))) = (0.03882±0.00032±0.00057), where the uncertainties are statistical and systematic, respectively. From these precision τ measurements, we test the standard model assumption of μ-e and τ-μ charge current lepton universality and provide determinations of |Vus| experimentally independent of the decay of a kaon.

Integrated preclinical and clinical development of mTOR inhibitors in pancreatic cancer

BACKGROUND

The purpose of this work was to determine the efficacy of inhibiting mammalian target of rapamycin (mTOR) in pancreatic cancer preclinical models and translate preclinical observations to the clinic.

METHODS

Temsirolimus (20 mg Kg(-1) daily) was administered to freshly generated pancreatic cancer xenografts. Tumour growth inhibition was determined after 28 days. Xenografts were characterised at baseline by gene expression and comparative genomic hybridisation. Patients with advanced, gemcitabine-resistant pancreatic cancer were treated with sirolimus (5 mg daily). The primary end point was 6-month survival rate (6mSR). Correlative studies included immunohistochemistry assessment of pathway expression in baseline tumours, drug pharmacokinetics (PKs), response assessment by FDG-PET and pharmacodynamic effects in peripheral-blood mononuclear cells (PBMCs).

RESULTS

In all, 4 of 17 xenografts (23%) responded to treatment. Sensitive tumours were characterised by gene copy number variations and overexpression of genes leading to activation of the PI3K/Akt/mTOR pathway. Activation of p70S6K correlated with drug activity in the preclinical studies. Sirolimus was well tolerated in the clinic, showed predictable PKs, exerted pathway inhibition in post-treatment PBMCs and resulted in a 6mSR of 26%. No correlation, however, was found between activated p70S6K in tumour tissues and anti-tumour effects.

CONCLUSION

Sirolimus activity in pancreatic cancer was marginal and not predicted by the selected biomarker.

Entry of hepatitis B virus: mechanism and new therapeutic target

Entry of hepatitis B virus (HBV) into human hepatocytes constitutes the initial step in viral infection. The study of HBV entry had long been hampered by the lack of efficient cell culture systems and small animal models. The situation was greatly improved in the last decade with the development of HBV-infectible HepaRG cell line and primary Tupaia hepatocyte culture. Armed with these new tools, marked progresses have been achieved in the elucidation of the mechanism of HBV entry. Plenty of evidences indicate that the viral large surface protein (LHBs) is essential for HBV entry. Several regions in the PreS1 domain of LHBs have been verified to contribute directly to the viral attachment. In addition, a myristate moiety linked to the N-terminal glycine of PreS1 appears critical for HBV infectivity. Recently, the cysteine-rich antigenic loop of the S domain was identified as another crucial determinant for HBV infectivity. On the other hand, several cellular proteins were implicated in HBV attachment to hepatic cells, though definitive proofs are required in support to their functional involvement in HBV infection. Aiming to blocking viral entry, a couple of approaches based on acylated PreS1-derived peptides and short PreS1-binding peptides are currently under investigation, which have the potential to become novel antiviral therapeutics.