No abstract

It is becoming apparent that the synthesis of nitric oxide (NO) from L-arginine not only explains endothelium-dependent vascular relaxation, but is a widespread mechanism for the regulation of cell function and communication. We examined the role of NO on the endogenous dopamine (DA) release from rat striatum. Nitroprusside, in the concentration range of 3-100 microM, induced a dose-dependent increase in the endogenous DA release from rat striatal slices. The maximal response was 330% over the baseline release. A higher concentration of nitroprusside (300 microM) produced an inhibitory effect on the spontaneous release of DA. L-Arginine (10 and 100 microM), a substrate in the NO-forming enzyme system, also produced an elevation of DA release. L-Arginine-induced DA release was attenuated by NG-monomethyl-L-arginine, an inhibitor of NO synthase. NADPH (1 microM), a cofactor of NO synthase, enhanced L-arginine-induced DA release. These results suggest a possible involvement of NO in the DA release process in rat striatum.

The imbalance of T-helper (Th) lymphocyte cytokine production may play an important role in immunopathogenesis of persistent hepatitis C virus (HCV) infection. To know whether an imbalance between Th1 and Th2 cytokines is present in chronic HCV infection, serum levels of Th1 cytokines, interferon gamma (IFN-gamma) and interleukin (IL)-2, and Th2 cytokines, IL-4 and IL-10, were measured using enzyme-linked immunosorbent assay in this study. Eighteen individuals with chronic HCV infection, 11 healthy subjects as normal controls and 10 chronic HBV infected patients as disease controls were observed. The results showed that the levels of Th2 cytokines (IL-4 and IL-10) were significantly increased in chronic HCV infected patients compared with normal controls (IL-4: 30.49+/-17.55 vs. 14.94+/-13.73, pg/ml, P<0.025; IL-10: 50.30+/-19.59 vs. 17.87+/-9.49, pg/ml, P<0.001). Similarly, the levels of Th1 cytokine, IL-2, was also elevated in individuals with chronic HCV infection when compared with normal controls (IL-2: 118.53+/-95.23 vs. 61.57+/-28.70, pg/ml, P<0.05). However, Th1 cytokine IFN-gamma level was not significantly changed during HCV infection (IFN-gamma: 28.09+/-15.65 vs. 24.10+/-15.61, pg/ml, P>0.05). Furthermore, the elevated levels of Th2 cytokines are greater than Th1 cytokines in HCV infection. Thus, the study indicates that an enhanced Th2 responses are present during chronic HCV infection, which may partly be responsible for the persistence of HCV infection.

A new 109Cd gamma-ray induced K-XRF bone lead measurement system using an array of four detectors has been developed. Previous results from Monte Carlo (MC) simulations and experiments with phantoms predicted that it would be about three times more sensitive than the conventional system, albeit using a more active source. A dosimetry study has been performed for this system and it demonstrated that the dose delivered to the measured individuals is acceptable even for 5-year-old children. Approval to apply this system to human studies has been received from the Research Ethics Board. In this study, 20 adult volunteers, 10 male, 10 female, were recruited to have their tibia measured with both the conventional system and the new system. The result confirmed the improvement predicted by the MC simulations and the in vitro measurements. Two other interesting points were discovered from the data. One is that the data from the new system showed a significant positive correlation between age and tibia lead concentration, while the data from the conventional system do not. The other is that 85% of the tibia lead concentrations were under the minimum detection limit when measured by the conventional system, and the proportion reduced to 50% when measured by the new system.