Correlation coefficients between the dioxin levels in mother's milk and the distances to the nearest waste incinerator which was the largest source of dioxins from each mother's place of residence in Tokyo, Japan.

BACKGROUND: To observe the relationship between the PCDD/F and Co-PCB levels in samples of human breast milk and nearby waste incinerators in Tokyo, Japan. METHODS: Breast milk was taken from 240 mothers residing in Tokyo, Japan to measure and analyze the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs; 14 congeners), polychlorinated dibenzofurans (PCDFs; 15 congeners), and coplanar polychlorinated biphenyls (Co-PCBs; 12 congeners) contained in the fat. Individual milk samples (about 50 ml) were obtained from the mothers 30 days after delivery, between the months of June and September in 1999 and 2000. A map of Tokyo was used to measure the distances between each mother's place of residence and the closest public and industrial waste incinerators. RESULTS: The distances to the nearest waste incinerators bore no apparent correlations with the congeners of PCDD/Fs and Co-PCBs. The distances were also uncorrelated with the mean toxic equivalent quantities (TEQs) of PCDD/Fs (the sum of PCDDs and PCDFs), Co-PCBs, and the total PCDD/Fs and Co-PCBs. CONCLUSIONS: Although waste incinerators were the largest source of dioxins in Japan at the time of the study, the dioxins levels of mother's milk bore no apparent relationships with the distances between the mothers' domiciles and the nearest waste incinerators. In this study, several meaningful factors were not taken into account, namely, the wind direction, the level of dioxin emitted from each incinerator, the level of environmental pollution of dioxins, and the average time the mothers stayed at home each day. A full understanding of these points awaits future studies.

PCDDs, PCdfs and Co-PCBs in human breast milk samples collected in Tokyo, Japan.

AIM: To observe the distribution of PCDD/Fs and Co-PCBs in samples of human breast milk collected in Japan. METHODS: Using high-resolution gas chromatography, milk samples for polychlorinated dibenzo-p-dioxins (PCDDs; 14 congeners), polychlorinated dibenzofurans (PCDFs; 15 congeners) and coplanar polychlorinated biphenyls (Co-PCBs; 12 congeners) from 240 mothers residing in Tokyo were analysed. There were 120 donors each of primiparae and secundiparae, each group including 60 donors aged 25 to 29 y ("the younger group") and 60 aged 30 to 34 y ("the older group"). Individual milk samples (about 50 ml) were obtained 30 d after delivery in 1999 and in 2000. RESULTS: The mean toxic equivalent (TEQ) level of PCDD/Fs (the sum of PCDDs and PCDFs) was 14.9 pg TEQ/g fat, of Co-PCBs 10.6 pg TEQ/g fat, and the total sum of PCDD/Fs and Co-PCBs was 25.6 pg TEQ/g fat. The mean TEQ levels of PCDD/Fs, Co-PCBs, and total PCDD/Fs and Co-PCBs were higher in primiparae than in secundiparae. In each of these, the levels were higher in the subgroup of older mothers. In the secundiparae, the mean levels were lower in the group of mothers who had breastfed their first babies than in those who bottle-fed or partly bottle-fed their first born. CONCLUSIONS: The concentrations of PCDD/Fs and Co-PCBs in the breast milk of Japanese women were slightly lower than those described in previous studies conducted in Japan and other countries; and the concentrations of PCDD/Fs and Co-PCBs in the breast milk were influenced mainly by the mother's age and nursing history.

Discovery and evaluation of piperidinyl carboxylic acid derivatives as potent alpha(4)beta(1) integrin antagonists.

Piperidinyl carboxylic acid-based derivatives were prepared as antagonists of the leukocyte cell adhesion process that is mediated through the interaction of the alpha(4)beta(1) integrin (VLA-4, very late antigen 4) and the vascular cell adhesion molecule 1 (VCAM-1). Compounds 2a-h inhibited the adhesion in a cell-based assay in the low and sub micromolar range, a pharmacokinetic study of 2d is reported.

Effect of phorbol esters on cytosolic Ca2+ level, myosin phosphorylation and muscle tension in high K(+)-stimulated bovine tracheal smooth muscle.

To determine the role of protein kinase C (PKC) in bovine tracheal smooth muscle contractility, we examined the effects of phorbol esters on cytosolic Ca2+ level ([Ca2+]i), myosin light chain (MLC) phosphorylation and contractile force in intact muscle and contraction in a permeabilized preparation. In intact muscle, 12-deoxyphorbol 13-isobutyrate (DPB, 1 microM) increased the force without changing [Ca2+]i. High K+ (72.7 mM) induced sustained contraction with sustained increase in [Ca2+]i. In the muscle stimulated by high K+, 50 nM DPB increased the contractile force without changing [Ca2+]i, and 1 microM DPB increased the contractile force with decreasing [Ca2+]i. Thus DPB shifted the [Ca2+]i/force relationship for high K+ to the lower [Ca2+]i in a concentration-dependent manner. In permeabilized muscle, DPB did not induce contraction in the absence of Ca2+ (< < 0 nM), but shifted the Ca2+/force relationship to the lower Ca2+ levels. In the muscle stimulated with high K+, DPB (50 nM and 1 microM) increased MLC phosphorylation and force without changing the MLC phosphorylation/force relationship. DPB (1 microM) increased PKC activity estimated by the translocation from the cytoplasm to the membrane. These results suggest that DPB increases the Ca2+ sensitivity of MLC phosphorylation via the activation of PKC. Furthermore, DPB at higher concentration has an inhibitory effect on stimulated [Ca2+]i.

Inhibitory effect of forskolin on myosin phosphorylation-dependent and independent contractions in bovine tracheal smooth muscle.

In bovine tracheal smooth muscle, carbachol (CCh, 1 microM) and high K+ (72.7 mM) induced sustained increases in cytosolic Ca2+ level ([Ca2+]i), myosin light chain (MLC) phosphorylation and force of contraction. Forskolin (FK, 1-10 microM) inhibited the CCh-induced increase in [Ca2+]i, MLC phosphorylation and force in parallel. In contrast, FK inhibited the high K(+)-induced contraction and MLC phosphorylation without changing [Ca2+]i. In the absence of extracellular Ca2+ (with 0.5 mM EGTA), CCh (10 microM) and caffeine (20 mM) induced transient increase in [Ca2+]i and contractile force by releasing Ca2+ from cellular store. FK strongly inhibited the CCh-induced Ca2+ transient, but failed to inhibit the caffeine-induced Ca2+ transient. In the absence of external Ca2+, 12-deoxyphorbol 13-isobutylate (DPB, 1 microM) induced sustained contraction without increase in [Ca2+]i and MLC phosphorylation. FK inhibited this contraction without changing [Ca2+]i. In permeabilized muscle, Ca2+ induced contraction in a concentration-dependent manner. FK (10 microM) and cAMP (1-100 microM) shifted the Ca(2+)-force curve to the higher Ca2+ levels. CCh with GTP, GTP gamma S or DPB enhanced contraction in the presence of constant level of Ca2+. Forskolin and cAMP also inhibited the enhanced contractions in the permeabilized muscle. In the permeabilized, thiophosphorylated muscle, ATP induced contraction in the absence of Ca2+. cAMP (300 microM) had no effect on this contraction. These results suggest that forskolin inhibits agonist-induced contraction in tracheal smooth muscle by multiple mechanisms of action; 1) inhibition of MLC phosphorylation by reducing Ca2+ influx and Ca2+ release, 2) inhibition of MLC phosphorylation by changing the MLC kinase/phosphatase balance, and 3) inhibition of regulatory mechanism which is not dependent on MLC phosphorylation.

Leakage of the fluorescent Ca2+ indicator fura-2 in smooth muscle.

The movement of a fluorescent intracellular Ca2+ indicator, fura-2, in smooth muscle was examined. Strips of rat and rabbit aortas and bovine trachea were loaded with the acetoxymethyl ester of fura-2 (fura-2/AM), followed by washing with normal physiological solution. Not only fura-2/AM but also fura-2 was detected in the washout solution. The amount of fura-2 in the cells, measured fluorometrically, decreased gradually during the washout. The decrease was fastest in rat aorta followed by rabbit aorta > bovine trachea. In rat aorta, fura-2 leakage was inhibited by an inhibitor of anion transport, probenecid, or by a decrease in bath temperature. The Ca2+ ionophore ionomycin (10 microM) increased the leakage of fura-2, which was not inhibited by probenecid, possibly because a high concentration of ionomycin nonselectively increased membrane permeability. These results suggest that fura-2/AM is cleaved to fura-2 in the cell which gradually leaked out of the cell mainly by an anion transport system. The amount of fura-2 in the cell seemed to be determined mainly by the rate of leakage of fura-2, which is the largest in rat aorta followed by rabbit aorta and bovine trachea.

Effect of a novel inhibitor of cyclic AMP phosphodiesterase, E-1020, on cytosolic Ca++ level and contraction in vascular smooth muscle.

1. The effects of a novel cyclic AMP phosphodiesterase inhibitor, E-1020 (1,2-dihydro-6-methyl-2-oxo-5-(imidazo[1,2-a]pyridin-6-yl)-3-pyridine carbonitrile hydrochloride monohydrate), on cytosolic Ca++ level ([Ca++]cyt) and muscle tension were examined in rat aorta using a fluorescent Ca++ indicator, fura-2. 2. The sustained contraction induced by norepinephrine was more strongly inhibited by E-1020 than that induced by high K+. The contraction induced by a higher concentration of the stimulant was less sensitive to E-1020 than that due to a lower concentration. 3. Contractions induced by high K+ and norepinephrine followed the increase in [Ca++]cyt. E-1020 inhibited the increments in [Ca++]cyt and muscle tension. A Ca++ channel blocker, verapamil, inhibited the norepinephrine-stimulated [Ca++]cyt more strongly than the contraction. E-1020 inhibited the verapamil-insensitive portion of the norepinephrine-stimulated [Ca++]cyt and contraction. 4. Norepinephrine transiently increased [Ca++]cyt and muscle tension in Ca(++)-free solution. E-1020 inhibited the transient contraction but not the stimulated [Ca++]cyt. 5. E-1020 increased the cyclic AMP content of the muscle. The effects of E-1020 on cyclic AMP content and contraction were potentiated by an activator of adenylate cyclase, forskolin. 6. These results suggest that E-1020 inhibits the vascular contractility by the decrease in [Ca++]cyt and decrease in Ca++ sensitivity of contractile elements. These effects may be mediated by the increase in cyclic AMP content of the muscle.

Changes in cytosolic CA2+ and contraction induced by various stimulants and relaxants in canine tracheal smooth muscle.

Effects of stimulants and relaxants on the cytosolic Ca2+ level [(Ca2+]cyt) and contraction were examined in isolated canine tracheal smooth muscle. High K+ and carbachol induced a sustained increase in [Ca2+]cyt and muscle tension. Cumulative addition of KCl induced a graded increase in [Ca2+]cyt and muscle tension. Cumulative addition of carbachol induced greater contraction than high K+ at a given [Ca2+]cyt 12-Deoxyphorbol 13-isobutyrate (DPB) (50 nmol/l) induced a small sustained contraction with little effect on [Ca2+]cyt. A higher concentration (1 mumol/l) of DPB induced a larger sustained contraction with a decrease in [Ca2+]cyt. DPB (50 nmol/l) potentiated the KCl-induced contraction without or with only a small additional increase in [Ca2+]cyt. By contrast, 1 mumol/l DPB potentiated the high-K(+)-induced contraction with a decrease in [Ca2+]cyt. Addition of 50 nmol/l or 1 mumol/l DPB in the presence of carbachol inhibited both [Ca2+]cyt and muscle tension. Verapamil, isoprenaline and forskolin did not change or slightly decreased [Ca2+]cyt and muscle tension in resting trachea. Verapamil inhibited the contraction and [Ca2+]cyt stimulated by high K+ and carbachol. Isoprenaline and forskolin inhibited the high-K(+)-induced contraction without changing [Ca2+]cyt, whereas these inhibitors inhibited carbachol-induced contraction with a relatively small decrease in [Ca2+]cyt. These results suggest that (a) sustained contractions induced by high K+ and carbachol are due to the sustained increase in [Ca2+]cyt, (b) carbachol increases the sensitivity of contractile elements to Ca2+, and (c) isoprenaline and forskolin inhibit the contraction by the decrease in [Ca2+]cyt and also by the decrease in the sensitivity of contractile elements to Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)