Beta-carotene and inhibitors of iron absorption modify iron uptake by Caco-2 cells.
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A National fortification program instituted in Venezuela in 1993 reduced iron deficiency and anemia by half in only 1 y. The fortification mixture contained ferrous fumarate, vitamin A and other vitamins. We conducted experiments to characterize ferrous fumarate uptake by Caco-2 cells. Increasing amounts of ferrous fumarate, vitamin A, phytate, tannic acid and beta-carotene were added to incubation mixtures using a range of concentrations that included the molar ratios used in the Venezuelan fortification program. Cells were incubated for 1 h at 37 degrees C with 37 kBq (59)Fe and the compound to be evaluated. They were then rinsed, trypsinized and counted to measure uptake. Effects of ascorbic acid, days in culture and use of flasks or inserts were also evaluated. Optimal conditions for uptake experiments were pH 5.5, in the presence of ascorbic acid and at 16 d in culture. Use of flasks or inserts did not affect uptake. Vitamin A did not significantly increase iron uptake under the experimental conditions employed. However, beta-carotene (6 micromol/L) significantly increased iron uptake compared to no beta-carotene addition (114.9 +/- 6.3 and 47.2 +/- 5.9 pmol/mg cell protein, respectively). Moreover, in the presence of phytates or tannic acid, beta-carotene generally overcame the inhibitory effects of both compounds depending on their concentrations. We conclude that beta-carotene improves iron uptake and overcomes the inhibition by potent inhibitors of iron absorption. These experiments also validated the usefulness of Caco-2 cell model system to evaluate iron metabolism. (+info)
Predominant contribution of the G protein-mediated mechanism to NaF-induced vascular contractions in diabetic rats: association with an increased level of G(qalpha) expression.
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The purpose of this study was to determine the mechanism responsible for alterations in NaF-induced contractions of blood vessels from streptozotocin-induced diabetic rats. In the presence of AlCl(3), NaF (>/=7.5 mM) produced significantly greater contractions in diabetic aorta and mesenteric artery compared with age-matched controls. Pretreatment with 1 microM nifedipine eliminated the enhanced contractile responses of diabetic vessels to NaF, resulting in no difference in the magnitude of NaF-induced contractions between control and diabetic vessels. In the presence of 100 microM deferoxamine, an Al(3+) chelator, NaF-induced contractions of diabetic vessels were markedly attenuated, whereas only the responses to lower concentrations of NaF were reduced in control vessels. No significant difference was found in the peak amplitude of transient contractions induced by 10 microM cyclopiazonic acid between control and diabetic vessels. The addition of 10 microM okadaic acid produced attenuated contractions in diabetic vessels. These findings indicate no involvement of the inhibitory effects of NaF on endoplasmic reticular Ca(2+)-pump ATPase and protein phosphatases in the genesis of the enhanced responsiveness of diabetic vessels to NaF. Western blot analysis showed a 2.5-fold increase in the expression of G(qalpha) in diabetic aortic membranes. In contrast, the G(ialpha) level was modestly decreased and the G(salpha) and G(betagamma) levels were unchanged in diabetes. The present results suggest that enhanced vascular contractions to NaF in diabetes is attributed predominantly to a G protein-mediated Ca(2+) channel activation that results from markedly increased G(qalpha) expression in vascular tissues under this pathological state. (+info)
Tumor necrosis factor-induced lethal hepatitis: pharmacological intervention with verapamil, tannic acid, picotamide and K76COOH.
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Tumor necrosis factor (TNF) induces hepatitis when injected in human beings or in rodents. The molecular mechanism by which TNF induces hepatic distress remains largely unknown, although induction of apoptosis of hepatocytes appears to be an essential step. In order to increase the therapeutic value of TNF, we have studied the protective activity of several molecules and found that four chemically totally different substances confer significant protection in the model of TNF-induced lethal hepatitis in mice sensitized with D-(+)-galactosamine (GalN), but not in mice sensitized with actinomycin-D (ActD) or against anti-Fas-induced lethal hepatitis. Verapamil, a calcium-channel blocker, tannic acid, picotamide, a thromboxane A(2) receptor antagonist, and K76COOH, an inhibitor, amongst others, of complement, protected significantly against induction of lethality, release of the liver-specific enzyme alanine aminotransferase (ALT) and induction of apoptosis in the liver after TNF/GalN, except for K76COOH, which paradoxically increased ALT values after challenge, and which also protected against TNF/GalN in complement-deficient mice. The data suggest that activation of platelets and neutrophils, as well as induction of inflammation occur in the TNF/GalN model, but not in the TNF/ActD or anti-Fas models, in which direct induction of apoptosis of hepatocytes may be more relevant. The protective activity of the drugs may lead to an increase in therapeutic value of TNF. (+info)
Aluminum chloride induces retinal changes in the rat.
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We studied rat retinal changes due to aluminum (Al) toxicosis with a transmission electron microscope (TEM) and an energy dispersive X-ray analyzer (EDXA). Normal 4-week-old Wistar Kyoto rats were divided randomly into Al toxicosis and control groups. The Al toxicosis group was injected ip with 0.3 ml of 4% aluminum chloride (AlCl3) per day every day for 16 weeks. The retina was examined with a TEM and EDXA at 8, 12, and 16 weeks after starting injections with AlCl3. There was a statistically significant increase in the serum Al concentration in the Al toxicosis group (p < 0.001). We observed prominent pathologic changes at 16 weeks after the first injections. Thin retinal pigment epithelium (RPE), and disappearance of the photoreceptor outer and inner segments and nuclei were observed. There were high-density irregular granules in the outer and inner plexiform layers and in the inner nuclear layer. We found dense granules in the cells, which remained between the RPE and the inner nuclear layer. EDXA detected Al in the high-density irregular granules in these areas. Al injected ip caused accumulation of Al in the rat retina and the destruction of photoreceptor cells. These findings indicate that Al is toxic to the retina. (+info)
Turbidity as a measure of salivary protein reactions with astringent substances.
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Binding of tannins to proline-rich proteins has been proposed as an initial step in the development of astringent sensations. In beer and fruit juices, formation of tannin-protein complexes leads to the well-known effect of haze development or turbidity. Two experiments examined the development of turbidity in human saliva when mixed with tannins as a potential in vitro correlate of astringent sensations. In the first study, haze was measured in filtered human saliva mixed with a range of tannic acid concentrations known to produce supra-threshold psychophysical responses. The second study examined relationships among individual differences in haze development and the magnitude of astringency ratings. Mostly negative correlations were found, consistent with the notion that high levels of salivary proteins protect oral tissues from the drying effects of tannic acid. (+info)
The Pap1-independent induction by metal ions of a third gene encoding glutathione S-transferase gene from the fission yeast.
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A third gene that encodes glutathione S-transferase (GSTIII) was previously cloned from the fission yeast Schizosaccharomyces pombe. Using the GSTIII-lacZ fusion plasmid pGDA-19, its expression was shown to be enhanced by various metal ions. In the present study, four additional fusion plasmids, pGDA-29, pGDA-39, PGDA-49, and pGDA-59, were designed to carry 998, 378, 276, and 115 bp upstream regions from the translational initiation point, respectively. The major activation region was located between -998 and -378 bp upstream of the GSTIII gene. Regulatory sequences that are responsible for the induction by metal ions reside between -998 and -378 bp and between -276 and -115 bp upstream of the gene. The overexpressed Pap1 exerts a repression effect on the GSTIII expression via -998 to approximately -378 bp region, whereas it exerts an activation effect on the GSTIII expression via -270 to approximately -115 bp region. However, the induction of the GSTIII gene by metal ions occurs independent of Pap1. (+info)
Skin protectant drug products for over-the-counter human use; astringent drug products; final monograph; direct final rule. Direct final rule.
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The Food and Drug Administration (FDA) is amending the regulation that established conditions under which over-the-counter (OTC) skin protectant astringent drug products are generally recognized as safe and effective and not misbranded. This action revises some labeling for astringent drug products to be consistent with the final rule for OTC skin protectant drug products (68 FR 33362, June 4, 2003) and adds labeling for certain small packages (styptic pencils). This action is part of FDA's ongoing review of OTC drug products. Elsewhere in this issue of the Federal Register, FDA is publishing a companion proposed rule, under FDA's usual procedure for notice-and-comment rulemaking, to provide a procedural framework to finalize the rule in the event the agency receives any significant adverse comments and withdraws this direct final rule. (+info)
Inhibition of poly(ADP-ribose) glycohydrolase by gallotannin selectively up-regulates expression of proinflammatory genes.
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Poly(ADP-ribose)-polymerase-1 (PARP-1) and poly(ADP-ribose) (PAR) are emerging key regulators of chromatin superstructure and transcriptional activation. Accordingly, both genetic inactivation of PARP-1 and pharmacological inhibition of PAR formation impair the expression of several genes, including those of the inflammatory response. In this study, we asked whether poly(ADP-ribose) glycohydrolase (PARG), the sole depoly(ADP-ribosyl)ating enzyme identified so far, also regulates gene expression. We report the novel finding that inhibition of PARG by gallotannin triggered nuclear accumulation of PAR and concomitant PAR-dependent expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), but not of interleukin-1beta and tumor necrosis factor-alpha, in cultured RAW 264.7 macrophages. Remarkably, silencing of PARG by means of small interfering RNA selectively impaired gallotannin-induced expression of iNOS and COX-2. Consistent with a PAR-dependent transcriptional activation, increases of iNOS and COX-2 transcripts were not caused by activation of transcription factors such as nuclear factor-kappaB, activator protein-1, signal transducer and activator of transcription-1 or interferon regulatory factor-1, nor by mRNA stabilization. Overall, our data provide the first evidence that pharmacological inhibition of PARG leads to PAR-dependent alteration of gene expression profiles in macrophages. (+info)