Evidence for an anomalous like-sign dimuon charge asymmetry

We measure the charge asymmetry A ≡ (N++ - N--)/(N++ + N--) of like-sign dimuon events in 6.1 fb-1 of pp collisions recorded with the D0 detector at a center-of-mass energy square root(s) = 1.96   TeV at the Fermilab Tevatron collider. From A we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.009 57 ± 0.002 51(stat) ± 0.001 46(sys). It differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(-0.6)(+0.5)) × 10(-4), and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.

Lipid peroxidation levels, total oxidant status and superoxide dismutase in serum, saliva and gingival crevicular fluid in chronic periodontitis patients before and after periodontal therapy

BACKGROUND

Recent data have demonstrated increased lipid peroxidation (LPO) levels and oxidative stress in periodontitis. Malondialdehyde (MDA) and superoxide dismutase (SOD) are both increased during oxidative stress. Furthermore, this study examined SOD concentration, total oxidative status (TOS) and MDA levels in periodontal patients and investigated the longitudinal effect of periodontal therapy on the index levels of chronic periodontitis (CP) patients.

METHODS

Serum, saliva and gingival crevicular fluid (GCF) samples were obtained from 48 CP patients and 35 healthy control subjects prior to, as well as after 16 weeks following non-surgical post-periodontal therapy. MDA, TOS and SOD and clinical parameters were determined pre- and post-therapy.

RESULTS

The levels of TOS and SOD values were significantly higher in the CP group than in the control group (p < 0.05), but only MDA in GCF. Post-periodontal therapy, serum, saliva and GCF TOS and SOD levels significantly decreased compared to basal levels (p < 0.05), but only MDA in GCF.

CONCLUSIONS

LPO was higher in the periodontal region, with TOS and SOD increasing both locally and peripherally. Non-surgical therapy can restore and control the subject antioxidant capacity by locally and systemically modifying the levels of MDA, TOS and SOD.

Phase II study of pre-operative radiotherapy with capecitabine and oxaliplatin for rectal cancer and carcinoembryonic antigen as a predictor of pathological tumour response

This study investigated the efficacy and tolerability of pre-operative radiotherapy with concurrent capecitabine and oxaliplatin in patients with rectal cancer. Forty-seven patients with rectal adenocarcinoma (stages T3 - T4; node-positive) were enrolled and received radiotherapy (46 Gy in 23 fractions) in combination with capecitabine (1000 mg/m(2) twice daily on days 1 - 14 and 22 - 35) and oxaliplatin (130 mg/m(2) on days 1 and 22) (XELOX regimen). The main endpoints were safety and efficacy, as assessed by pathological complete response (pCR). All patients received pre-operative chemoradiotherapy (CRT) as planned. The most common severe toxicity was diarrhoea (12.8%); post-operative complications were rare (9.8%). The pCR rate was 20.9% in all patients and 34.8% in patients with normal pre-CRT serum carcinoembryonic antigen (CEA < or = 5 ng/ml) level, compared with 5.0% in the patients with elevated CEA (> 5 ng/ml). In conclusion, pre-operative radiotherapy with concurrent XELOX regimen in rectal cancer patients is feasible and effective. Serum CEA may be a suitable predictor of pCR.

The neuronal repellent SLIT2 is a target for repression by EZH2 in prostate cancer

The neuronal repellent SLIT2 is repressed in a number of cancer types primarily through promoter hypermethylation. SLIT2, however, has not been studied in prostate cancer. Through genome-wide location analysis we identified SLIT2 as a target of Polycomb group (PcG) protein EZH2. The EZH2-containing Polycomb repressive complexes bound to the SLIT2 promoter inhibiting its expression. SLIT2 was down-regulated in a majority of metastatic prostate tumors exhibiting a negative correlation with EZH2. This repressed expression could be restored by methylation inhibitors or EZH2-suppressing compounds. In addition, a low level of SLIT2 expression was associated with aggressive prostate, breast and lung cancers. Functional assays showed that SLIT2 inhibited prostate cancer cell proliferation and invasion. Thus, this study demonstrated for the first time epigenetic silencing of SLIT2 in prostate tumors, and supported SLIT2 as a potential biomarker for aggressive solid tumors. Importantly, PcG-mediated repression may serve as a precursor for the silencing of SLIT2 by DNA methylation in cancer.

Superconducting properties of copper oxide high-temperature superconductors

The equations for the magnon pairing theory of high-temperature copper-oxide-based superconductors are solved and used to calculate several properties, leading to results for specific heat and critical magnetic fields consistent with experimental results. In addition, the theory suggests an explanation of why there are two sets of transition temperatures (T(c) approximately 90 K and T(c) approximately 55 K) for the Y(1)Ba(2)Cu(3)O(6+x) class of superconductors. It also provides an explanation of why La(2-x)Sr(x)CuO(4) is a superconductor for only a small range of x (and suggests an experiment to independently test the theory). These results provide support for the magnon pairing theory of high-temperature superconductors. On the basis of the theory, some suggestions are made for improving these materials.

Stability and Activities of Antibiotics Produced during Infection of the Insect Galleria mellonella by Two Isolates of Xenorhabdus nematophilus

Xenorhabdus nematophilus subsp. dutki, an entomopathogenic bacterium, is vectored by steinernematid nematodes into insects, where it produces broad-spectrum antibiotics. The use of the nematode-bacterium complex against soil-dwelling pest insects could introduce antibiotics into the soil via the dead insect fragments during the emergence phase of the nematodes. Studies on the stability and activities of these antibiotics produced in the insect Galleria mellonella may contribute to assessing the possible impact of antibiotics on soil bacteria. Two isolates of X. nematophilus subsp. dutki (isolates GI and SFU) produced xenocoumacins 1 and 2 in cadavers of G. mellonella larvae in a 1:1 ratio. Total xenocoumacin 1 and 2 production was 800 ng/200 mg (wet weight) of insect tissue for the GI isolate. Antibiotic activity of water extracts from insects that had been infected with X. nematophilus was stable at 60 degrees C for 1 h and after repeated freeze-thaw cycles. The antibiotic titer of extracts held at 27 degrees C declined by day 10. The spectrum of bacterial species killed by antibiotics produced in insect cadavers varied with the isolate of X. nematophilus. Levels of antibiotic activity were greater in vivo than in tryptic soy broth, which may represent a nutrient effect. The bacterial isolate, culture condition, and presence of nematodes influenced the total antibiotic production in vivo. However, the levels of activity were not correlated with bacterial levels in the different growth environments. Insect cadavers with antibiotic activity transiently lowered the numbers of the bacteria in the soil, the extent of decline varying with the strain of X. nematophilus and the time of sampling.

Search for Randall-Sundrum gravitons in the dielectron and diphoton final states with 5.4 fb(-1) of data from pp collisions at square root(s) = 1.96 TeV

Using 5.4  fb(-1) of integrated luminosity from pp collisions at square root(s)=1.96  TeV collected by the D0 detector at the Fermilab Tevatron Collider, we search for decays of the lightest Kaluza-Klein mode of the graviton in the Randall-Sundrum model to ee and γγ. We set 95% C.L. lower limits on the mass of the lightest graviton between 560 and 1050 GeV for values of the coupling k/M(Pl) between 0.01 and 0.1.

Pregnane X receptor suppresses proliferation and tumourigenicity of colon cancer cells

BACKGROUND

Pregnane X receptor (PXR) is a nuclear receptor that regulates the metabolism and disposition of various xenobiotics and endobioitics. We investigated a novel PXR function in regulating colon tumourigenesis in this study.

METHODS

Histochemistry, transfection, cell proliferation assay, anchorage-alpha-dependent assay, xenograft, immunohistochemistry, immunofluorescence flow cytometry.

RESULTS

Using histochemistry analysis, we found that PXR expressions were lost or greatly diminished in many colon tumours. Ectopic expression of human PXR through stable transfection of PXR into colon cancer cell line HT29 significantly inhibited cell proliferation as determined by cell proliferation assay and anchorage-independent assay. Pregnane X receptor suppressed significantly HT29 xenograft tumour growth in nude mice compared with control (310+/-6.2 vs 120+/-6 mg, P<0.01). Immunohistochemistry and immunofluorescence analysis of Ki-67 on excised xenograft tumour tissues showed that PXR inhibited cancer cell proliferation. Furthermore, expressions of PXR and Ki-67 were mutually exclusive. The flow cytometry analysis indicated that PXR caused G(0)/G(1) cell-cycle arrest. p21(WAF1/CIP1) expression was markedly elevated whereas E2F1 expression was inhibited by PXR.

CONCLUSION

PXR inhibits the proliferation and tumourigenicity of colon cancer cells by controlling cell cycle at G(0)/G(1) cell phase by regulating p21(WAF1/CIP1) and E2F/Rb pathways.