Ic Compatible Processing of Si:Er for optoelectronics

We have fabricated the first Si:Er LED, operating at 300 K, based on an understanding of the Si-Er-O materials system. Er-doped Si (Si:Er) provides an exciting opportunity for the monolithic integration of Si based opto-electronics. In this paper, Er-Si reactivity, and Er diffusivity and solubility have been studied to establish Si:Er process compatibility with a silicon IC fabline. Er3 Si5 is the most stable silicid formed; and it can be oxidized into Er2O3 at high temperature under any oxidizing conditions. Among Er compounds, Er2O3 luminesces and Er3Si5 and ErN do not. The diffusivity of Er in Si is low and SIMS analysis yields a diffusivity D(Er) ∼ 10−12cm2/s at 1300 C and ∼ 10−15cm2/s at 900 C, and a migration enthalpy of δHm(Er) ∼ 4.6 eV. The equilibrium solubility of Er in Si is in the range of 1016 cm−3 at 1300 C. The Si:Er LED performance is compared with GaAs LEDs to demonstrate its feasibility.

Presence of anti-insulin natural autoantibodies in healthy cats and its interference with immunoassay for serum insulin concentrations

A substance interfering with the enzyme-linked immunosorbent assay (ELISA) for feline insulin concentration was investigated in healthy cats. An insulin-binding substance isolated from feline serum showed 2 bands at 25 and 50 kDa in SDS-PAGE, suggesting the presence of immunoglobulin G (IgG). Insulin-binding IgG from healthy cats indeed reduced insulin immunoreactivity in the ELISA for determining insulin concentration. The insulin-binding IgG was polyclonal/polyreactive and showed certain specificity, high affinity, and high binding capacity, which was evaluated by liquid-phase radioimmunoassay with Scatchard plot analysis. Epitope analysis revealed that the insulin-binding IgG showed significant binding at residues A1-5 and B20-30 of the insulin molecule. Removal of the antibodies from serum enabled the determination of serum insulin concentrations by ELISA. Our data indicated that serum from healthy cats contained substantial amounts of natural autoantibodies combined with insulin, and that the antibodies interfered with the heterologous immunoassay for serum insulin concentration.

Isoflurane attenuates myoglobin release during ischemic and/or reperfusion periods

BACKGROUND

Recently, we have developed cardiac microdialysis for detection of protein leakage from the injured myocardium. We examined whether the exposures to isoflurane would exert a beneficial effect on myocardial injury caused by ischemia or reperfusion.

METHODS

A dialysis probe was implanted into the left ventricle free wall in the rabbits. The dialysate myoglobin level served as an index of myocardial interstitial myoglobin levels. Rabbits were randomly assigned to one of three groups: (1) without exposure to isoflurane (vehicle, n=6), (2) inhale 1 MAC isoflurane once for 30 min (ISO30-1, n=6), and (3) twice for 30 min (ISO30-2, n=6). All rabbits underwent 30 min of coronary occlusion and 60 min of reperfusion. To determine whether the isoflurane induced myocardial protection against chemical hypoxia, sodium cyanide (30 mM) was administered and dialysate myoglobin levels were measured with (n=6) and without pre-exposure to isoflurane twice for 30 min (n=6).

RESULTS

In all three groups dialysate myoglobin levels were increased by coronary occlusion and furthermore augmented by reperfusion. In comparison with the vehicle group, the ISO30-1 group suppressed only the increase in the dialysate myoglobin level during reperfusion. The ISO30-2 group suppressed during both the ischemic and reperfusion periods. Cyanide induced increases in dialysate myoglobin levels. These increments in dialysate myoglobin levels were suppressed by repeated exposure to isoflurane.

CONCLUSION

Repeated exposure to isoflurane suppressed myocardial myoglobin release caused by both ischemia and reperfusion injury. Isoflurane may provide protection against myocardial ischemia/reperfusion and hypoxic injuries.

Characterization of ouabain-induced noradrenaline and acetylcholine release from in situ cardiac autonomic nerve endings

AIM

Although ouabain modulates autonomic nerve ending function, it is uncertain whether ouabain-induced releasing mechanism differs between in vivo sympathetic and parasympathetic nerve endings. Using cardiac dialysis, we examined how ouabain induces neurotransmitter release from autonomic nerve ending.

METHODS

Dialysis probe was implanted in left ventricle, and dialysate noradrenaline (NA) or acetylcholine (ACh) levels in the anaesthetized cats were measured as indices of neurotransmitter release from post-ganglionic autonomic nerve endings.

RESULTS

Locally applied ouabain (100 microm) increased in dialysate NA or ACh levels. The ouabain-induced increases in NA levels remained unaffected by cardiac sympathetic denervation and tetrodotoxin (Na+ channel blocker, TTX), but the ouabain-induced increases in ACh levels were attenuated by TTX. The ouabain-induced increases in NA levels were suppressed by pretreatment with desipramine (NA transport blocker) and augmented by reserpine (vesicle NA transport blocker). In contrast, the ouabain-induced increases in ACh levels remained unaffected by pretreatment with hemicholinium-3 (choline transport blocker) but suppressed by vesamicol (vesicle ACh transport blocker). The ouabain-induced increases in NA levels were suppressed by pretreatment with omega-conotoxin GVIA (N-type Ca2+ channel blocker), verapamil (L-type Ca2+ channel blocker) and TMB-8 (intracellular Ca2+ antagonist). The ouabain-induced increases in ACh levels were suppressed by pretreatment with omega-conotoxin MVIIC (P/Q-type Ca2+ channel blocker), and TMB-8.

CONCLUSIONS

Ouabain-induced NA release is attributable to the mechanisms of regional exocytosis and/or carrier-mediated outward transport of NA, from stored NA vesicle and/or axoplasma, respectively, while the ouabain-induced ACh release is attributable to the mechanism of exocytosis, which is triggered by regional depolarization. At both sympathetic and parasympathetic nerve endings, the regional exocytosis is because of opening of calcium channels and intracellular calcium mobilization.

A second-generation profiling system for quantitative methylation analysis of multiple gene promoters: application to lung cancer

Cancer-specific gene promoter methylation has been described in many types of cancers, and various semi-quantified results have shown their usefulness. Here, we show a more sensitive and specific second-generation system for profiling the DNA methylation status. This method is based on bisulfite reaction of DNA and real-time PCR using two TaqMan MGB probes labeled with different fluorescence, followed by clustering analysis. Primers were designed with CpG-less sequences, and TaqMan MGB probes were designed to contain three or four CpG sites and to be shorter than conventional TaqMan probes. We have added new criteria for primer and probe design for further specificity. We confirmed the reliability of this system and applied it to analysis of lung cancers. Using 10 promoters, 90 primary lung cancers were clustered into six groups consisting of cases having similar smoking status and pathological findings. EGFR mutation and p16 promoter DNA methylation were exclusive, as previously reported; however, DNA methylation in other genes was unrelated to EGFR mutation. This system was also useful to distinguish double primary lung cancers from a single cancer with intrapulmonary metastasis. As above, our system has widespread availability in clinical use and biological research.