Monophosphoryl lipid A was prepared from the lipopolysaccharide of Chlamydia trachomatis, converted to the methyl ester, and fractionated by reverse-phase high-performance liquid chromatography. The peak fractions were collected and analyzed by mass spectrometry. Matrix-assisted laser desorption/ionization and liquid secondary ion mass spectrometry of the first of two major high-performance liquid chromatographic fractions showed multiple quasi-molecular ions of MNa+ at m/z 1780, 1794, 1808, 1822, and 1836. The positive-ion liquid secondary ion mass spectrometry spectrum also showed a minor series of peaks at m/z 1916, 1930, 1944, 1958, and 1971, consistent with the formation of matrix adducts with 3-nitrobenzyl alcohol. Oxonium ions representing the distal subunit were observed at m/z 1057, 1071, 1085, 1099, and 1113. The second fraction was similarly analyzed and found to contain structural homologs of the first fraction. Based on this study, the major lipid A component of chlamydial lipopolysaccharide is a glucosamine disaccharide that contains five fatty acids and a phosphate in the distal segment. Three fatty acyl groups are in the distal segment, and two are in the reducing end segment. The acyloxyacyl group is located in the distal segment in amide linkage. Two structural series, differing by 14 atomic mass units in the reducing subunit, were observed. Chlamydial lipid A is complex and consists of at least 20 homologous structural components. The relatively low potency of Chlamydia trachomatis lipopolysaccharide in activating lipopolysaccharide-responsive cells might be related to the unusual fatty acid composition of the lipid A moiety.

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The slurry sampling technique has been applied for the determination of arsenic, cadmium and lead in sidestream cigarette smoke condensate (SS CSC) by inductively coupled plasma mass spectrometry (ICP-MS). The smoke collection system consists of a "fishtail" chimney in conjunction with an impaction trap and a mixed cellulose ester (MCE) backup filter for the SS CSC collection. The smoke condensates, collected at three different regions of the system (i.e. the inner wall of the chimney, the impaction trap and the MCE filter), were individually prepared and analyzed and showed that about 70 and 20% of Cd and Pb, respectively, were trapped by the impaction trap and the MCE filter with less than 5% trapped by the chimney. In contrast, about 60% of As was trapped by the impactor and a relatively high percentage of As, about 30%, was deposited onto the inner wall of the chimney. The uneven distribution of trace metals at each collection stage strongly suggested that the composition of smoke aerosol and the associated physical form of the analytes may be different. The yields of As, Cd and Pb for the sidestream cigarette smoke of the 1R4F reference cigarette were 29.5 +/- 2.4, 421 +/- 6.6 and 46.4 +/- 0.9 ng cigarette(-1)(n= 3) respectively, when the cigarette was smoked according to the smoking regime: 45 mL puff volume of 2-s puff duration at an interval of 30 s with 50% ventilation holes covered. The analytical results for the slurry sampling technique were also compared with other sample preparation techniques and show good agreement.

The effect of continuous-wave (CW) and pulsed-wave (PW) radiofrequency radiation (RFR) in the microwave range on UV-induced DNA repair has been investigated in MRC-5 normal human diploid fibroblasts. RFR exposure at power densities of 1 (or 5) and 10 mW/cm2 gave a maximum specific absorption rate (SAR) (at 10 mW/cm2) of 0.39 +/- 0.15 W/kg for 350 MHz RFR, 4.5 +/- 3.0 W/kg for 850 MHz RFR, and 2.7 +/- 1.6 W/kg for 1.2 GHz RFR. RFR exposures for 1 to 3 h at 37 degrees C, in either continuous-wave or pulsed-wave modes, had no effect on the rate of repair replication label incorporated into preexisting UV-damaged DNA. RFR exposures (PW), with a constant medium temperature of 39 degrees C at 350 and 850 MHz during the repair period after UV damage, also had no effect. Assay for induction of repair synthesis by RFR exposure alone in non-UV irradiated cells was negative for the 350-, 850-, and 1200-MHz CW and PW RFR at 37 degrees C and the 350- and 850-MHz PW RFR at 39 degrees C. RFR does not induce DNA repair under these exposure conditions. In preliminary experiments--with the tissue culture medium maintained at 39 degrees C and RFR exposures (PW) at the frequencies of 350, 850, and 1200 MHz--no effect on incorporation of [3H]thymidine into DNA undergoing semiconservative synthesis was observed.