Spin-dependent low-energy 4He+ ion scattering from nonmagnetic surfaces

We investigated electron-spin-polarized (4)He(+) ion scattering on various nonmagnetic surfaces at kinetic energies below 2 keV. It was observed that the scattered He(+) ion yield depends on the He(+) ion spin. We interpret this spin-dependent scattering in terms of the spin-orbit coupling that acts transiently on the He(+)1s electron spin in the He(+)-target binary collision. This interpretation qualitatively explains the relationship between the spin-dependent scattering and the scattering geometry, incident velocity, and magnetic field arrangement. This is the first study to report spin-orbit coupling caused by projectile electron spin in ion scattering.

Placental inflammation and oxidative stress in the mouse model of assisted reproduction

Higher rates of low birth weight and prematurity are observed in pregnancies generated with assisted reproduction technologies (ART). Both conditions have been associated with placental inflammation and oxidative stress. Since placental and fetal levels of progesterone, a major anti-inflammatory steroid, are decreased in murine ART, we investigated placental inflammation and oxidative stress in this model as potential mediators of negative birth outcomes. After generating mouse pregnancies by in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) we evaluated the antioxidant defense network and major inflammatory cytokines in maternal, placental and fetal tissues. Additionally, placentas were analyzed for total lipid levels, fibrosis, apoptosis, reactive oxygen species and integrity of intracellular nucleotides. Placentas from ART contained significantly less lipids, with greater levels of apoptosis and degraded nucleotides. Placentas from ICSI pregnancies had lower activities of superoxide dismutase (SOD), thioredoxin reductase (TrxR), xanthine oxidase (XO), catalase, glutathione-S-transferase (GST) glutathione peroxidase, and glutathione reductase (GR). Furthermore, GR, GST and SOD were also lower in fetal livers from ICSI pregnancies. Placentas from IVF pregnancies had decreased levels of SOD, TrxR and XO only. In placentas from both ICSI and IVF pregnancies IL-6 levels were significantly increased. These data suggest that ART is associated with placental inflammation (IL-6), oxidative stress and apoptosis but not fibrosis or remodeling. These effects are markedly greater with the ICSI technique. Since ICSI is ubiquitous, oxidative stress and placental inflammation associated with this method may be a critical factor in negative birth outcomes such as prematurity and low birth weight.

Intracellular bacteria recognition contributes to maximal interleukin (IL)-12 production by IL-10-deficient macrophages

Interleukin (IL)-12 is a key factor that induces T helper cell type 1-mediated immunity and inflammatory diseases. In some colitis models, such as IL-10 knock-out (KO) mice, IL-12 triggers intestinal inflammation. An abundant amount of IL-12 is produced by intestinal macrophages in response to stimulation by commensal bacteria in IL-10 KO mice. Intact bacteria are more potent inducers of macrophage IL-12 production than cell surface components in this model. This suggested that cell surface receptor signalling and intracellular pathogen recognition mechanisms are important for the induction of IL-12. We addressed the importance of intracellular recognition mechanisms and demonstrated that signal transducers and activator of transcription 1 (STAT1) signalling activated bacterial phagocytosis and was involved in the induction of abnormal IL-12 production. In IL-10 KO mouse bone marrow-derived (BM) macrophages, Escherichia coli stimulation induced increased IL-12p70 production compared to lipopolysaccharide combined with interferon (IFN)-γ treatment. Significant repression of IL-12 production was achieved by inhibition of phagocytosis with cytochalasin D, and inhibition of de novo protein synthesis with cycloheximide. Induction of IFN regulatory factors-1 and -8, downstream molecules of STAT1 and the key transcription factors for IK-12 transcription, following E. coli stimulation, were mediated by phagocytosis. Interestingly, STAT1 was activated after stimulation with E. coli in IL-10 KO BM macrophages, although IFN-γ could not be detected. These data suggest that molecules other than IFN-γ are involved in hyper-production mechanisms of IL-12 induced by E. coli stimulation. In conclusion, enteric bacteria stimulate excessive IL-12p70 production in IL-10 KO BM macrophages via phagocytosis-dependent signalling.

A Metastable-atom Deexcitation Spectroscopy (MDS) study on the First Atomic Layer of a Polycrystalline Titanium Surface

The oxygen adsorption on a polycrystalline titanium surface at room temperature has been studied by MDS in conjunction with UPS and AES. MDS and UPS spectra were measured using a pulsed-dischaxge-type metastable helium atom source which we have newly developed. FRom the analysis of the measured spectra, we found the following about the local density of states (LDOS) of the oxygen-adsorbed titanium surface: (1) With increasing oxygen exposure at 0-2 L, the LDOS on the first atomic layer (SDOS) at 0-1 eV below the Fermi level (EF) decreases more steeply than that of deeper layers. (2) The SDOS at 5–8 eV below EF remains small at 0-2 L, and begins to increase at ca. 2 L while the LDOS of subsurface layer increases first. We discuss the positions of adsorbed oxygen atoms based on these results.

Silicon micro/nanofabrication using metastable helium atom beam lithography

We utilize metastable helium (He*) atom beam lithography to pattern silicon substrates by using self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) grown directly on silicon surface as resist. An improved wet-chemical etching method was used to transfer the resist pattern into silicon substrate. Negative and positive pattern formations with well-defined edges were observed for silicon(100) substrate with SAM after exposure to the He* atom beam followed by the etching. Results indicate a clear transition from positive to negative patterns relies on the He* dosage. The pattern sizes on silicon were successfully decreased to the order of 100 nm, even less than 50 nm.

Identification of a novel planarian G-protein-coupled receptor that responds to serotonin in Xenopus laevis oocytes

Planarians are useful animals for regenerative and neuroscience research at the molecular level. Previously, we have reported the distribution and function of neurotransmitter-synthesizing neurons in the planarian central nervous system. In order to understand the neural projections and connections, it is important to understand the distribution of neurotransmitter receptors. In this study, we isolated a serotonin receptor gene and named it DjSER-7 (Dugesia japonica serotonin receptor type 7). DjSER-7-expressing cells were distributed in the planarian brain. According to electrophysiological analysis using Xenopus oocytes, current response was detected upon exposure to serotonin, but not other neurotransmitters in oocytes that were co-injected with mRNAs of both DjSER-7 and Galpha chimera B-2, which can interact with either Gq-, Gs- or Gi-coupled receptor. In contrast, current response was not detected after exposure to neurotransmitters in oocytes injected with only DjSER-7 mRNA. Our results indicated that DjSER-7 responds to serotonin, as indicated by electrophysiological analysis using Xenopus oocytes.

Assessment of the safety and efficacy of percutaneous cryoablation for lung tumors

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Background: Percutaneous cryoablation using high resolution fluoroscopic CT guidance under local anesthesia offers a potential tool for local control of lung tumors in combination with systemic treatments. In this study, we retrospectively analyzed the safety, and efficacy of percutaneous cryoablation for lung tumors (PCLT). Methods: This study was approved by the institutional review board. From October 2002, PCLT was performed in patients who either did not oncologically fulfill the indications for resection, or refused resection. CT scan was examined every 3 months after PCLT. >20% increase in the treated lesion size was diagnosed as local failure. Survival analysis was done by Kaplan-Meier. Results: There were 147 patients (95 male, 52 female, mean age 60, 20 primary lung cancer, metastases; 29 of lung cancer, 35 of colorectal cancer, 63 of other sites). 251 sessions were done for 462 tumors. Mean tumor diameter was 18.3mm. PCLT was well tolerated in most patients. In 1 case, broncho-thoracic fistula occurred in the treated region which lead to empyema. Other complications were pneumothorax (153 sessions, 61%, chest tube required in 23 sessions), pleural effusion (160 sessions, 64%), and transient hemoptysis (82 sessions, 33%). Overall one- and two-year local control rates were 81.0% and 59.1%, respectively. Overall one- and two-year survival rates were 80.0% and 54.5%, respectively. In the 1–20 mm sized (n=362) vs. over 21mm sized (n=100) lesions, the local control rates at one year were 84% vs. 56% (p=0.0007), and at two years were 63% vs. 35% (p=0.017), respectively. There were no differences in local control between primary and metastatic tumors, carcinomas and sarcomas. Survival of patients whose lesions were limited to 1–20mm (n=89) was prolonged vs. those who had at least one over 21mm lesion (n=58) (p=0.01). However, one, and two-year survival rates did not differ significantly between these groups (one-year; 85.5% vs. 71.7% (p=0.07), two-year; 60.7% vs. 46.5% (p=0.16)). Conclusions: PCLT was minimally invasive and safe. 1–20mm tumors were good candidates. Contribution of PCLT to survival was not clear in this mixed patient population. To improve local control in over 20 mm tumors, we are computer simulating freezing kinetics to optimize the number and the positioning of the probes.

No significant financial relationships to disclose.