Particle-bound PAH content in ambient air.

Ambient air samples from a traffic intersection, an urban site and a petrochemical-industrial site (PCI) were collected by using several dry deposition plates, two Microorifice uniform deposited impactors (MOUDIs), one Noll Rotary Impactor (NRI) and several PS-1 (General Metal Work) samplers from March 1994 to June 1995 in southern Taiwan, to characterize the atmospheric particle-bound PAH content of these three areas. Twenty-one individual polycyclic aromatic hydrocarbons (PAHs) were analyzed primarily by using a gas chromatograph/mass spectrometer (GC/MS). In general, the sub-micron particles have a higher PAH content. This is due to the fact that soot from combustion sources consists primarily of fine particles and has a high PAH content. In addition, a smaller particle has a higher specific surface area and therefore may contain more organic carbon, which allows for more PAH adsorption. For a particle size range between 0.31 and 3.2 microm, both Urban/Traffic and PCI/Traffic ratios of particle-bound total-PAH content have the lowest values, ranging from 0.25 to 0.28 (mean = 0.26) and from 0.07 to 0.13 (mean = 0.10), respectively. This indicates that, during the accumulation process, the PAH mass shifted from a particle phase to a gas phase, or the particles aggregated with lower PAH-content particles, resulting in a reduction in particle-bound PAH content. By using the particle size distribution data, the dry deposition model in this study can provide a good prediction for the PAH content of dry deposition materials. In general, lower molecular weight PAHs had a larger fraction of dry deposition flux contributed by the gas phase; for 2-ring PAH (50.4, 46.3 and 28.4%), 3-ring PAHs (15.2, 15.4 and 11.7%) and 4-ring PAHs (13.0, 3.60 and 5.01%) for the traffic intersection, urban and PCI sites, respectively. For higher molecular weight PAHs-5-ring, 6-ring and 7-ring PAHs-their cumulation fraction (F%) of dry deposition flux contributed by the gas phase was lower than 3.26%. At the traffic intersection, urban and PCI sites, the mass median diameter of dry deposition materials (MMD(F)) of individual PAHs was between 25.3 and 49.6 microm, between 27.6 and 43.9 microm, and between 19.1 and 41.9 microm, respectively. This is due to the fact that PAH dry-deposition primarily resulted from gravitational settling of the coarse particulates (> 10 microm).

Cell-cycle-dependent alterations of a highly phosphorylated nucleolar protein p130 are associated with nucleologenesis.

We identified a novel human nucleolar phosphoprotein p130 (130 kDa) using a strategy for selecting monoclonal antibodies against nuclear proteins which oscillate in the cell cycle. p130 is localized in interphase nucleoli in a dotted manner. Complete extraction of p130 required a high concentration of salt (0.5 M NaCl) indicating that it binds firmly to the nucleolar components via ionic interaction. p130 is heavily phosphorylated, since alkaline phosphatase treatment converted the purified p130 into a 95 kDa product; this was further supported by the in vitro demonstration that cellular phosphatase and casein kinase II activities were responsible for the interchange of these two forms. Extracts of mitotic cells had lower concentrations of p130 compared to those of interphase cells suggesting that a proportion of p130 might be degraded during mitosis. Moreover, all the remaining p130 in mitotic cells was further phosphorylated, likely by a cdc2 kinase, resulting in increase in its solubility, and its dispersion throughout the entire cytoplasm. Thus, p130 in metaphase and anaphase cells was unable to be detected by immunofluorescence microscopy. At telophase, p130 reappeared and aggregated into a granular structure, resembling the prenucleolar bodies. These granules migrated from the nucleoplasm to the nucleoli in early G1-phase. Actinomycin D was able to induce segregation of p130-containing granules into the nucleoplasm, similar to the well-known behavior of the fibrillarin-containing granules, indicating that p130 is localized in the dense fibrillar component, a subnucleolar region for pre-rRNA synthesis and processing. The cDNA sequence of p130 revealed a remarkable feature, that a serine-rich stretch interspersed with acidic residues is repeated ten times. Such a characteristic is shared with a rat nucleolar phosphoprotein Nopp140, which is thought to shuttle between the nucleolus and the cytoplasm. Although p130 shows 74% identity to Nopp140, our observations suggest that during mitosis the functions of p130 are related to nucleologenesis.

Effect of aging on renal cytochrome P450-dependent arachidonic acid metabolism in Dahl rats.

We investigated the age-related changes of renal cytochrome P450-dependent arachidonic acid metabolism in 3-, 5-, 7-, 9-, 11-, 13- and 20-week-old male Dahl salt-sensitive (DS) and -resistant (DR) rats on a low sodium diet (0.3% NaCl). NADPH-dependent arachidonic acid metabolism was separated and measured by a radio-HPLC system. The formation of 19-hydroxyeicosatetraenoic acid (HETE), 20 HETE, 1,20-dioic acid, epoxyeicosatrienoic acids (EETs), and dihydroxyeicosatrienoic acid (DHET) was age dependent in both DS and DR rats. omega-Hydroxylase (20-HETE and 1,20-dioic acid formation) and (omega-1)-hydroxylase (19-HETE formation) were increased from 3 to 5 weeks age, then decreased with aging in DR rats. Whilst omega/(omega-1)-hydroxylase activities were increased from 3- to 9-week-old rats, they decreased with aging in DS rats. omega/(omega-1)-Hydroxylase activities were higher in 3-5-week-old DR than DS rats. Epoxygenase activities (EETs and DHET formations) were highest in 3-week-old DS and DR rats, and showed no significant differences between two strains of rats at any ages tested. Renal cytochrome P450-dependent arachidonic acid metabolites have a wide and contrasting spectrum of biological and renal effects, and their relative rates of production may influence not only renal hemodynamics but also pro- and antihypertensive mechanisms of hypertension in Dahl rats.

Roles of renal cytochrome P450-dependent arachidonic acid metabolites in hypertension.

Cytochrome P450 represents the third metabolic pathway of arachidonic acid giving rise to several biologically active compounds, such as 19-HETE, 20-HETE and EETs and their corresponding DHETs. The kidney is the rich source of these metabolites which have some important biologic actions within the kidney. These metabolites have a wide and contrasting spectrum of biological and renal effects, from vasodilation to vasoconstriction and from inhibition to stimulation of Na-K-ATPase, their relative production rates may influence not only renal hemodynamics but also pro- and anti-hypertensive mechanisms of hypertension. There is increasing evidence that the abnormality of these metabolites in animal models of hypertension. However, sufficient evidence of the physiological and pathophysiological roles of hypertension in man is still lacking.

Acute effect of manidipine on renal blood flow measured by pulsed-Doppler flowmeter in normal subjects.

The purpose of this study was to examine the effect of manidipine hydrochloride, a new calcium antagonist, on renal blood flow in healthy subjects, using the newly developed pulsed-Doppler flowmeter with colored flow imager and digital computer analyzer. Results in previous studies differed because the para-aminohippurate clearance method measures the average not real-time value. Sixteen healthy volunteers (n = 7, manidipine 20 mg; n = 9, placebo control) participated in the study. Before and 1 h after drug administration, pulsed-Doppler measurements were carried out by transabdominal approach with patients in the supine position. Manidipine hydrochloride increased renal blood flow significantly compared with placebo (13.8 +/- 4.7% vs. 6.1 +/- 5.6%; p < 0.05). There was a significant (p < 0.005) between group difference in the reduction in systolic blood pressure (-14.8 +/- 1.6 mmHg manidipine; -3.0 +/- 2.1 mmHg placebo). These data suggest that manidipine hydrochloride has a vasodilating effect on renal arterioles and a beneficial effect on the kidneys of hypertensive patients. Further, the pulsed-Doppler flowmeter may become a very useful tool for noninvasive measurement of renal blood flow.

[Responsiveness of cultured papillary collecting tubules to vasoactive hormones: comparison between spontaneously hypertensive rats and Wistar-Kyoto rats].

To investigate whether altered renal medullary prostaglandin (PG) synthesis is involved in the development of hypertension in spontaneously hypertensive rats (SHR), we compared the hormonal responsiveness of cultured renal papillary collecting tubule (RPCT) cells from SHR and Wistar-Kyoto rats (WKY) as control. Basal levels of PGE2 and cAMP were lower in 4-weeks-old SHR than in WKY, while PGE2 synthesis after stimulation with arachidonate, A23187 or bradykinin and the level of cAMP responded to vasopressin or exogenous PGE2 were similar in both strains. There was no difference in basal nor stimulated levels of cGMP between both strains. In 16-week-old rats, basal levels of cAMP, cGMP and PGE2 were significantly lower than in 4-week-old rats, but no differences were recognized between both strains. These results suggest that RPCT cells of SHR and WKY at the post-weaning period may differ in the metabolism of PGE2 and cAMP. This difference may be attributed to the possible defect in arachidonate availability in SHR.