Local site effects on weak and strong ground motion

The site amplification factor at a soil site determined from regression analysis of strong motion data shows departure from that estimated by the coda method for weak motion except for rock site stations. The record at stiff-soil site station Gil roy #2 is analysed using the record at Gilroy #1 underlain by weathered sandstone as an input motion, assuming a 1-D non-linear model. The synthesized results show good agreement with observed records in both time histories and response spectra. The maximum surface accelerations are greater than the maximum base accelerations in the linear regime at low levels of input motion (PGA more or equal 0.3 g), including the cases of the 1979 Coyote Lake earthquake and 1984 Morgan Hill earthquake. At a higher level of input rock acceleration, the nonlinear effect diminished the peak acceleration at the surface and tended to saturate to a limit of about 0.4 g which is in agreement with the observed strong ground motions during the Loma Prieta earthquake (PGA=0.44 g) (AU)

Differences in the in vivo and in vitro effects of the carbamate insecticide, carbaryl on rat hepatic monooxygenases.

The effects of one of the most widely used insecticides, carbaryl, on the hepatic cytochrome P-450-dependent monooxygenases were determined. Addition of carbaryl to liver microsomes from untreated or phenobarbital (PB)-pretreated rats resulted in a weak Type I binding spectrum. A much stronger spectral Type I interaction was observed when microsomes from 3-methylcholanthrene(3-MC)-treated rats were used. In vitro, carbaryl caused marked inhibition of ethylmorphine and benzphetamine N-demethylases, benzo(a)pyrene hydroxylase, 7-ethoxycoumarin and 7-ethoxyresorufin O-deethylase in liver microsomes. Kinetic studies demonstrated that carbaryl was a competitive inhibitor of ethylmorphine N-demethylase activity. Daily administration of carbaryl for 4 days by gavage or intraperitoneally resulted in no significant alterations in hepatic cytochrome P-450 levels, ethylmorphine N-demethylase or benzo(a)-pyrene hydroxylase activities. The lack of effect of carbaryl in vivo may be due to the rapid metabolism of the insecticide, such that the insecticide may not be present in the liver endoplasmic reticulum to cause the inhibitory effects observed in vitro.

Metabolism of carbaryl by kidney, liver, and lung from human postembryonic fetal autopsy tissue.

Metabolic profiles of carbaryl in human postembryonic fetal autopsy tissue were determined using an in vitro tissue-maintenance technique. 1-Naphthyl-14C or N-methyl-14C-carbaryl was applied to growth medium containing explants of the tissue. Each mixture was incubated for 18 hr and the medium analyzed by DEAE-cellulose column chromatography. Fetal liver performed the metabolic processes of demethylation, hydrolysis, hydroxylation, and oxidation, followed by conjugation, as was found with adult liver. However, the anionics from fetal liver amounts to 20% of those found with adult liver. The kidney made naphthyl glucuronide and naphthyl sulfate, whereas the lung produced naphthyl sulfate from carbaryl. The metabolic activities of the fetal kidney and lung were close to the corresponding human adult tissues based upon the anionic metabolites found and the amount of unmetabolized carbaryl in the medium after 18 hr of incubation. Silica gel chromatography of ether-extractable neutral fractions from DEAE-cellulose revealed 3,4, and 9 ether-extractable metabolites from lung, kidney, and liver, respectively. The present study shows that the in vitro technique is capable of semiquantitatively demonstrating the metabolic activities of specific organs from the human fetus.