[Determination of water soluble silicon from herbal drugs]

This article has set up a method for silicon determination by ammonium molybdate-ferrous sulfate-sodium carbonate spectrophotometry. The method is simple, convenient, quick, effective and free of the influence of phosphate ion and reducing agents such as vitamin C and so on. By this method water soluble silicon has been determined in 38 herbal drugs.

[Effect of high-frequency oscillation on hypoxic pulmonary vasoconstriction]

We studied the effect of high-frequency oscillatory ventilation (HFO) on hypoxic pulmonary vasoconstriction (HPV) in mongrel dogs. Arterial blood gas as well as pulmonary and systemic hemodynamic variables were measured. Using a double-lumen endotracheal catheter, the right lung was ventilated by controlled mechanical ventilation (CMV) and the left lung was ventilated by CMV (controlled group, n = 5), HFO (HFO group, n = 6) and a combined use of CMV and HFO (combined group, n = 6). Under the same condition as in HFO group, chest was opened and the left pulmonary arterial flow was determined by electromagnetic method (opened thorax group, n = 4). Bilateral lungs were ventilated with pure oxygen during the control period. The right lung was ventilated with pure oxygen while the left lung was ventilated with pure nitrogen afterward during the study. There was no significant change in arterial oxygen partial pressure due to delayed HPV in HFO group or combined group between 30 and 120 minute values. Although there was an increase in mean pulmonary arterial pressure in combined group, in HFO group it was not observed. At the same time, the decrease in pulmonary flow was minimum in open thorax group. Authors conclude that HFO interferes with the effect of HPV to a certain extent.

Effect of fatty acids on formation, distribution, storage, and release of benzo(a)pyrene phenols and glucuronides in the isolated perfused rat liver

The hydroxylation of benzo(a)pyrene and conjugation, storage, and release of benzo(a)pyrene phenols and glucuronides by the perfused rat liver were studied in the presence and absence of acute addition of physiological concentrations of common dietary fatty acids. The actions of fatty acids on the oxidation and conjugation of benzo(a)pyrene in the intact liver were compared with their actions on microsomes isolated from rat liver. Rats were treated with beta-naphthoflavone to stimulate polycyclic aromatic hydrocarbon metabolism. Long-chain fatty acyl CoA compounds (palmitoyl CoA, oleoyl CoA, linolenoyl CoA; 50 microM) inhibited hydroxylation of benzo(a)pyrene by isolated microsomes by about 45%; however, long-chain fatty acids did not affect overall rates of hydroxylation of benzo(a)pyrene by the perfused liver at concentrations ranging up to 300 microM. The medium-chain acyl CoA compound, octanoyl CoA, also did not affect benzo(a)pyrene hydroxylation in microsomes or liver. Although fatty acids did not alter rates of hydroxylation, the ratio of free benzo(a)pyrene phenols to glucuronides (F/G ratio) increased about 60% (P less than 0.05) in livers perfused with long-chain fatty acids (palmitate, oleate, linolenate). Inhibition of glucuronidation was not observed with the medium-chain fatty acid, octanoate. Benzo(a)pyrene phenols and glucuronides accumulated linearly in the liver at rates of approximately 40 nmol/g/h. A second action of both long- and medium-chain length fatty acids was to increase rates of release of benzopyrene phenols into the perfusate by 50 to 80%. Fatty acids did not effect release of benzo(a)pyrene phenols and glucuronides into bile. Taken together, these data support the hypothesis that fatty acids displace carcinogenic metabolites of benzo(a)pyrene from binding sites in the liver which enter the circulation and travel to target tissues.