A cationic peroxidase gene (Shpx6a) of a forage legume species, Stylosanthes humilis, was transferred to poplar (Populus tremula) in antisense orientation under the control of 35S RNA promoter of cauliflower mosaic virus. Transformed plants were regenerated on selective media after co-cultivation of poplar stem explants with Agrobacterium tumefaciens and integration of transgenes was confirmed by PCR and Southern hybridization analyses. Analyses of selected transgenic plants showed reductions in total leaf peroxidase activity which was 50% to 70% of that measured in untransformed control plants. Transgenic poplar plants with reduced leaf peroxidase activity had 10-20% lower lignin content than control plants. Although which isoform of poplar peroxidase (s) has been inhibited by 35S-Shpx6a antisense construct is not clearly known, our results suggested the possibility of manipulation of lignin content through inhibition of lignin-specific peroxidases.

The dependence on laser intensity of recently discovered plateau structures in laser-assisted x-ray‐atom scattering, both with and without a static electric field present, is analyzed. Using the ‘‘three-step’’ model and the strong-field approximation we demonstrate a connection between laser-assisted, x-ray‐atom scattering and high-order harmonic generation: For high laser-field intensities without a static field present, both processes have plateaus whose energies extend to the cutoff value 3.17Up , where Up is the ponderomotive potential energy. For x-ray‐atom scattering in the presence of a static electric field we show that at high laser-field intensities two plateaus appear: One is our recently predicted high-energy plateau for the same process @Phys. Rev. Lett. 81, 5097 ~1998!#, while the other, low-energy plateau, has a differential cross section six orders of magnitude larger. The energy positions and relative magnitudes of these new plateaus are explained using semiclassical arguments. @S1050-2947~99!07211-X#

OBJECTIVE Previous studies have pointed to the changes of serum angiotensin-converting enzyme (SACE) values in patients with liver disease and cancer located in different sites. The aim of this study was to determine the changes in SACE values in patients with hepatocellular carcinoma (HCC) and liver cirrhosis. METHODS The study comprised 30 patients with HCC (22 men and eight women) of average age 48.6 +/- 9.0 years and 30 patients with liver cirrhosis (21 men, nine women) of average age 49.1 +/- 9.5 years. The control group consisted of 30 healthy volunteers with matching anthropometric characteristics. SACE activity was determined by a spectrophotometric method using synthetic hippuryl-glycyl-glycine as substrate. RESULTS The mean SACE value was considerably lower in patients with HCC, 22.8 U/ml (95% CI, 22.5-23.9), both those in whom HCC developed in cirrhotic liver (n = 23), 23.7 (22.9-24.5) as well as those with HCC without cirrhosis (n = 7), 21.8 (21.0-22.6), with regard to patients with liver cirrhosis, 37.2 (36.6-37.8) (P < 0.001). There was also a statistically significant difference between healthy, 29.9 (29.4-30.3), and both groups of HCC patients (P < 0.001). No significant differences could be found between the group of HCC patients with and without liver cirrhosis (P < 0.05). In patients with liver cirrhosis SACE value was increased in accordance with the severity of the disease expressed by Child's classification; however, at each stage SACE values were considerably lower in patients with HCC in cirrhotic liver (Child A, 35.8 vs 22.1; Child B, 38.7 vs 24.2; Child C, 40.0 vs 28.3) (P < 0.001). Alfa-fetoprotein (AFP) values did not correlate with the SACE activity. The SACE value was also significantly decreased in patients with HCC whose AFP were not altered. CONCLUSION The study has shown that SACE values are low in patients with advanced HCC. It may be helpful in detecting HCC in patients with cirrhosis, where it can be difficult to differentiate between small HCC tumours and regeneration nodules.

A generalization of the Dirac field equation in three-dimensional Minkowski space-time to the case of the $\bar{SL}(3,R)$ $\subset$ $\bar{SA}(3,R)$ symmetry is considered. Constraints that ensure a correct physical interpretation of the corresponding particle states are presented. Dirac-like equations based on both multiplicity-free and generic infinite-component $\bar{SL}(3,R)$ representations are outlined.