Secondary ion mass spectrometry method for distinguishing the state of carbon in steels using negative molecular ions

The analytical utility of the negative molecular spectrum in secondary ion mass spectrometry (SIMS) was examined using the Fe-C system as a model system. A series of plain carbon steels ranging in carbon concentration from 0.08 to 0.8 wt pct was investigated both in the austenitized-quenched and tempered conditions to establish the mass spectral differences arising due to the difference in the state of carbon. The results showed that SIMS was sensitive to the state of carbon in the alloy and that the presence of cementite could be easily detected. The application of SIMS to characterize microstructures is demonstrated by examples.     

Quantification of mitral and tricuspid regurgitation by the proximal flow convergence method using two-dimensional colour Doppler and colour Doppler M-mode: influence of the mechanism of regurgitation

Tamoxifen (10 pg/ml) was infused directly into superfused striatal tissue fragments of ovariectomized rats for a 50 min period. Immediately following the termination of tamoxifen there was a significant increase in dopamine output compared with non-infused controls. No such significant increase was observed with use of a 100 pg/ml tamoxifen dose. Although dopamine output was again increased upon termination of a 2 h infusion of tamoxifen, these levels failed to differ significantly from that of non-infused controls. Similarly, a shorter 10 min duration infusion of tamoxifen failed to alter dopamine output. Finally, we examined whether the tamoxifen-induced, post-infusion increase in dopamine output, as observed following a 50 min infusion of 10 pg/ml, involved a calcium dependent process. To achieve this goal, superfusions were performed with Calcium/Tamoxifen, No Calcium/Tamoxifen, No Calcium/No Tamoxifen and Calcium/No Tamoxifen. A significant increase in dopamine output post-tamoxifen infusion was obtained for the Calcium/Tamoxifen condition compared with the remaining three groups which failed to differ from one another. Taken together these results show that tamoxifen can alter dopamine output through direct, non-genomic effects upon striatal neurons. Responses to this anti-estrogen are intriguing since they are apparent following removal, but not during tamoxifen infusion and represent a calcium-dependent process. These data suggest that tamoxifen may represent an important modulator of nigrostriatal dopaminergic function.     

Kinetics and mechanism of the reductive ammonia leaching of ocean nodules by manganous ion

The kinetics of reductive ammonia leaching of ocean nodules by manganous ion were found to be chemically controlled. The rates of Cu, Ni and Co extraction all show an order of dependence of 0.5 each on total ammonia and manganous ion. The logarithm of metal ion extraction rates vs. pH shows a maximum at about pH 9.0 to 9.5. The orders with respect to [H⁺] are −0.5 and 0.5, respectively, in the pH ranges of 7.0 to 9.0 and 9.5 to 11.0, due to various protolytic equilibria involving ammonia and Mn(II). The rates of metal ion extraction have the order Cu > Ni > Co. A chemical surface-leaching reaction mechanism is proposed, involving adsorption of manganous ammine on the nodule lattice, thereby liberating Cu, Ni and Co minerals, which are subsequently dissolved due to metal ammine formation.     

Analysis of the thromboxane/prostacyclin balance in human urine by gas chromatography/selected ion monitoring: abnormalities in diabetics

Mouse fibroblasts (B-6) were cultured on agar-coated dishes. After cells grew for 2-3 generations relatively rapidly in suspension, they began to grow very slowly (stationary phase). Electron microscopic studies showed that cells in a stationary phase developed intracellular organella: membranous structures (endoplasmic reticulum and Golgi apparatus) became manifest and the number of mitochondria increased. The specific activities of succiniccytochrome c reductase and 5'-nucleotidase were three and five times higher, respectively, than those of cells on the dish.     

Detection of Helicobacter pylori by culture and the 13C-urea breath test using an automated breath 13C analyzer

Up to now, the diagnosis of H. pylori infection has been made by the breath test using 13C-urea. In this study, 13C-urea breath samples were tested in 34 patients (peptic ulcer scar 17, chronic gastritis 17 cases) with an automated breath 13C analyzer (ABCA. Europa Scientific, Crewe, UK) and compared with the results of endoscopical diagnosis for H. pylori infection. Endoscopic and 13C-urea breath test (13C-UBT) were performed before eradicative medication. We described a modified protocol for the growth grade of H. pylori colonies in microbiology (H. pylori score), and for the delta 13C area under curve (AUC; permil*hr) obtained from each sample of expired breath. There was a significant correlation between delta 13C-AUC and the delta 13C level of each sample, but the correlation coefficient obtained at 10min (R2 = 0.582) was lower than that obtained at the other four time points (20min; 0.891, 30min; 0.949, 40min; 0.946, 50min; 0.946, 60min; 0.820). The delta 13C-AUC well correlated with H. pylori score (p < 0.01), none of 26 H. pylori positive patients detected by culture was 13C-UBT negative (delta 13C-AUC < 8.2 permil*hr in mean + 2SD of H. pylori negative group). In conclusion, 13C-UBT using ABCA has high sensitivity and specificity, and it provides a non-invasive method for the detection of H. pylori urease activity.     

Quantification of human immunodeficiency virus type 1 RNA levels in plasma by using small-volume-format branched-DNA assays

We have developed small-volume (50 or 250 microl)-format branched-DNA assays for human immunodeficiency virus type 1 (HIV-1) RNA for use with specimens in which the volume is limited and/or a high viral load is anticipated. These formats exhibited good correlation with the standard 1-ml format; high specificity, reproducibility, and linearity; and no significant difference in the quantification of HIV-1 subtypes.