Arylamine N-acetyltransferase (NAT) activities with 2-aminofluorene and p-aminobenzoic acid were determined in the bacterium Helicobacter pylori collected from peptic ulcer patients. Cytosols or suspensions of H. pylori with or without specific concentrations of rhein co-treatment showed different percentages of 2-aminofluorene and p-aminobenzoic acid acetylation. The data indicate that there was decreased NAT activity associated with increased levels of rhein in H. pylori cytosols. Inhibition of growth studies from H. pylori demonstrated that rhein elicited dose-dependent bacteriostatic activity in H. pylori cultures: i.e. the greater the concentration of rhein, the greater the inhibition of growth to H. pylori. For the cytosol and intact bacteria examination, the apparent values of Km and Vmax were decreased after co-treatment with 40 microM rhein. This report is the first demonstration of rhein inhibition of arylamine N-acetyltransferase activity and rhein inhibition of growth in the bacterium H. pylori.

4-Aminobenzoic Acid↗

PubMedDate not supplied

Ibuprofen affects arylamine N-acetyltransferase activity in Helicobacter pylori from peptic ulcer patients.

Arylamine N-acetyltransferase (NAT) activities with 2-aminofluorene and p-aminobenzoic acid were determined in the bacterium Helicobacter pylori collected from peptic ulcer patients. Cytosols or suspensions of H. pylori with or without specific concentrations of ibuprofen co-treatment showed different percentages of 2-aminofluorene and p-aminobenzoic acid acetylation. The data indicate that there was decreased NAT activity associated with increased levels of ibuprofen in H. pylori cytosols. Inhibition of growth studies on H. pylori demonstrated that ibuprofen elicited a dose-dependent bactericide effect in H. pylori cultures, i.e. the greater the concentration of ibuprofen, the greater the inhibition of growth to H. pylori. For the cytosol and intact bacteria examinations, the apparent values of Km and Vmax were decreased after co-treatment with 40 microM ibuprofen. This report is the first demonstration of ibuprofen inhibition of arylamine N-acetyltransferase activity and ibuprofen inhibition of growth in the bacterium H. pylori.

Arylamine N-Acetyltransferase↗

PubMedDate not supplied

Cyclosporine-associated encephalopathy: a case report and literature review.

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Adult↗

PubMedDate not supplied

The relationship between [Ca2+]i and cell death using an in vivo model: a study using the ced-1 mutant strain of C. elegans.

The ced-1 mutant of the free-living nematode, Caenorhabitis elegans, was used to study cell injury and cell death in relation to changes in intracellular ionized calcium ([Ca2+]i). This animal, which is being genetically characterized, may prove to be extremely useful for certain toxicologic studies because of its small size, optical transparency, rapid generation time, and the morphologic and genetic data currently available. During the development of this animal, 131 of 1,090 ultimate somatic cells undergo programmed cell death. Using mutagenesis techniques, several genes responsible for this death have been identified. In this study, we have taken advantage of the ced-1 mutant in which dead cells accumulate, as they cannot be phagocytized and removed. Although changes in [Ca2+]i have been studied in relation to cell injury and cell death, observations have been essentially restricted to in vitro monolayer cultures because of the methodology involved. To study the relationship between changes in [Ca2+]i and injury in vivo, we selected this animal model for further study and report here the morphological changes following the effects of ionomycin treatment in relation to increases of [Ca2+]i and cell death as measured using the fluorescent probes Fluo-3/AM and propidium iodide, respectively. The technique of confocal laser scanning microscopy is ideally adapted to such measurements in these living animals, and the results can be readily correlated with those made with Nomarski differential interference contrast microscopy as well as with transmission electron microscopy. The results support previous in vitro observations and show that early increases of [Ca2+]i accompany early reactions to injury. Furthermore, the results also show that changes in this small invertebrate metazoan parallel those seen in mammalian systems, including human. Thus, the current study indicates that ced-1 C. elegans can potentially serve as an in vivo model not only for evaluating the possible temporal relationship of [Ca2+]i elevation with cell death but also for evaluating the [Ca2+]i elevation observed in relation to other phenomena and in evaluating toxic agents.

Animals↗

PubMedDate not supplied

Characterization of a renal epithelial cell model of apoptosis using okadaic acid and the NRK-52E cell line.

Apoptotic cell death plays an important role in the pathogenesis of renal tubular epithelial damage and repair following tubular injury. Presently, the cellular factors involved in regulating apoptotic pathways in the kidney are unknown. To address the possibility that protein phosphorylation may regulate apoptosis in kidney cells, okadaic acid (OKA), a specific inhibitor of protein phosphatases 1A and 2A, was tested for its morphologic and biochemical effects on normal rat kidney epithelial cells (NRK-52E) in culture. As revealed by the DNA-specific stain DAPI, nuclei of cells treated with 1.0 microM okadaic acid contained irregular clumps of dense chromatin. Additional morphologic alterations typical of apoptosis were apparent within 2 hr after treatment with 1.0 microM OKA, including marked cellular rounding, cytoplasmic condensation, and cytoplasmic blebs. Ultrastructurally, 1.0 microM OKA caused cytoplasmic bleb formation, cellular fragmentation, condensation of heterochromatin into clumps, and segregation of nucleoli. At this stage, the cytoplasmic fragments and blebs contained many normal mitochondria. The attached, rounded cells also effectively excluded propidium iodide, demonstrating maintenance of membrane integrity despite pronounced morphologic alterations. A 2-fold increase in intracellular free Ca2+ was apparent 90 min after treatment with 1.0 microM okadaic acid. Transverse alternating field electrophoresis revealed the appearance of large DNA fragments of approximately 300-kbp. The appearance of these 300-kbp fragments correlated temporally with the observed elevation in intracellular calcium and the onset of morphologic alterations. However, preloading cells with EGTA-AM, an intracellular calcium chelator, obliterated the calcium elevation and had no effect on OKA-induced morphology, DNA fragmentation, or cell death. Detectable internucleosomal fragmentation occurred much later than the onset of morphologic changes (24-hr treatment time) and did not correlate with elevations in cellular calcium. These studies support the hypothesis that during apoptosis, chromatin condensation reflects chromatin cleavage at nuclease-sensitive sites between hexameric rosettes. These results also suggest that morphologic and nuclear alterations in the pathway of OKA-induced apoptosis occur independent of observed increases in intracellular calcium.

Animals↗

PubMedDate not supplied

The pathways of cell death: oncosis, apoptosis, and necrosis.

The pathways and identification of cell injury and cell death are of key importance to the practice of diagnostic and research toxicologic pathology. Following a lethal injury, cellular reactions are initially reversible. Currently, we recognize two patterns, oncosis and apoptosis. Oncosis, derived from the Greek word "swelling," is the common pattern of change in infarcts and in zonal killing following chemical toxicity, e.g., centrilobular hepatic necrosis after CC14 toxicity. In this common reaction, the earliest changes involve cytoplasmic blebbing, dilatation of the endoplasmic reticulum (ER), swelling of the cytosol, normal or condensed mitochondria, and chromatin clumping in the nucleus. In apoptosis, the early changes involve cell shrinkage, cytosolic shrinkage, more marked chromatin clumping, cytoplasmic blebbing, swollen ER on occasion, and mitochondria that are normal or condensed. Following cell death, both types undergo postmortem changes collectively termed "necrosis." In the case of oncosis, this typically involves broad zones of cells while, in the case of apoptosis, the cells and/or the fragments are often phagocytized prior to their death by adjacent macrophages or parenchymal cells. In either case, the changes converge to a pattern that involves mitochondrial swelling, mitochondrial flocculent densities and/or calcification, karyolysis, and disruption of plasmalemmal continuity. The biochemical mechanisms of cell death are currently under intense study, particularly concerning the genes involved in the process. Pro-death genes include p53, the ced-3/ICE proteases, and the Bax family. Anti-death genes include ced-9/Bcl-2 and the adenovirus protein EIB. It is clear that ion deregulation, particularly that of [Ca2+]i plays an important role in cell death following either apoptosis or oncosis. Genetic evidence strongly indicates that activation of proteases is an important step, possibly very near to the point where cell death occurs.

Animals↗

PubMedDate not supplied

Urinary excretion of hippuric acid after consumption of nonalcoholic beverages.

To investigate the types and quantities of beverages that increase urinary hippuric acid (HA) excretion, the authors recruited 137 healthy medical students and divided them into quintiles according to consumption of benzoic acid (BA) in beverages. Using chromatography, urinary HA before and 1.5 hours and 3 hours after consumption of various beverages and BA consumption in the beverages were measured. The mean age of the group was 24.2 years; 21 were female. The range of BA in 13 beverages was 0-1.02 mg/mL. The geometric means of urinary HA before consuming them in five groups were 0.276, 0.270, 0.207, 0.262, and 0.316 g/L, respectively (p = 0. 567); 1.5 hours after consuming the beverages, they were 0.210, 0. 603, 1.026, 1.066, and 1.688 g/L, respectively, and significantly increased after adjustment for urinary HA before ingestion (p < 0. 001). Three hours after ingestion, the geometric means were 0.160, 0. 232, 0.306, 0.287, and 0.337 g/L, respectively (p < 0.001). The authors estimate that beverages that contain more than 100 mg BA could increase urinary HA excretion significantly, up to 1.12 g/L without toluene exposure. Checking dietary and beverage-intake histories is essential in the interpretation of urinary HA concentrations in population studies.

Adult↗

PubMedDate not supplied

Transtubular potassium concentration gradient (TTKG) and urine ammonium in differential diagnosis of hypokalemia.

BACKGROUND: Hypokalemia is a common and sometimes serious clinical problem, whose etiological diagnosis can frequently be based on the patient's history and the clinical setting. Measurement of urinary indices such as excretory rate of K+, random urine K+ concentrations and blood acid-base parameters have been employed in the pathophysiological diagnosis, though with some pitfalls. METHODS: To investigate the diagnostic usefulness of the transtubular potassium concentration gradient (TTKG) and urine ammonium in the differentiation of hypokalemia, we measured serum K+ and osmolality, random urine electrolytes, osmolality and ammonium, the urinary [Na]/[K] ratio (U(Na)/K), plasma aldosterone and TTKG in 7 patients with diarrhea, 6 with vomiting, 7 with mineralocorticoid excess, 6 with diuretic usage, and compared them with those of 7 overnight fasted and acid-loaded healthy volunteers. RESULTS: The urine K+ concentrations did not reflect urinary loss of potassium according to the subjects' hydration status. U(Na)/k in the hypokalemic patients with mineralocorticoid excess (1.4 +/- 0.5) was lower than in normal subjects (2.3 +/- 0.4) (p<0.05). TTKG was higher in hypokalemic patients with mineralocorticoid excess (13.3 +/- 4.4) and diuretic usage (8.6 +/- 1.3) and lower in those with diarrhea (1.6 +/- 0.3) than in the normal controls (5.0 +/- 0.7) (p<0.5). TTKG in the patients with vomiting (3.5 +/- 0.6) was the same as in normal controls. TTKG was stronger correlated with the plasma aldosterone levels in the hypokalemic patients due to renal potassium loss. Urine ammonium concentrations of the acid-loaded normal subjects (73.3 +/- 5.0 mEq/L), patients with diarrhea (74.4 +/- 2.0 mEq/L) and patients with mineralocorticoid excess (68.7 +/- 6.9 mEq/L) were higher than in overnight-fasted normal subjects (31.3 +/- 4.9 mEq/L). CONCLUSION: TTKG and random urine ammonium were useful in the pathophysiological differential diagnosis of hypokalemia.

Diagnosis, Differential↗

PubMedDate not supplied

Effects of the butylated hydroxyanisole and butylated hydroxytoluene on the DNA adduct formation and arylamines N-acetyltransferase activity in human colon tumor cells.

The effects of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on N-acetyltransferase (NAT) activity were examined using a human colon tumor cell line (colo 205). BHA or BHT were added to the cytosols or to the medium of human colon tumor cells: The NAT activity was measured by high performance liquid chromatography, assaying the amounts of acetylated 2-aminoflluorene (AAF), p aminobenzoic acid (N-Ac-PABA), nonacetylated 2 aminofluorene (AF) and p-aminobenzoic acid (PABA). The NAT activity in the human colon tumor cells and cytosols was suppressed by BHA or BHT in a dose-dependent manner. The apparent values of Km and Vmax of NAT of human colon tumor cells were also decreased by BHA or BHT in cytosols and in intact cells. BHA or BHT may act as a noncompetitive inhibitor. After the incubation of human colon tumor cells with AF in the presence of BHA or BHT, the cells were recovered and DNA was prepared and hydrolysed to nucleotides. Adducted nucleotides were extracted into butanol and AF-DNA adducts were analysed by HPLC. The results also demonstrated that when BHA or BHT was added to the media, a decrease in AF-DNA adduct formation was seen in the human colon tumor cells. The finding of AF-DNA adduct formation in cultured human colon tumor cells suggest the possibility of using cultured cells for assessing arylamine-induced DNA damage.

2-Acetylaminofluorene↗

PubMedDate not supplied

Use of cisapride with magnesium oxide in chronic pediatric constipation.

Functional constipation in children is a common problem in daily practice, however there is currently no accepted optimal treatment of choice. This study investigated the effect of cisapride in the treatment of pediatric constipation when combined with magnesium oxide (MgO). This prospective study enrolled children with chronic constipation. They were randomly assigned to either MgO (125 mg three times a day for patients weighing less than 20 kg or 250 mg three times a day for those weighing more than 20 kg), or cisapride 0.2 mg/kg (max 5mg/dose) plus MgO for 4 weeks. Twenty-one doctors in 19 major medical centers or hospitals in Taiwan with well- established pediatric departments participated in this study from October 1999 to March 2000. 84 children (51 males, 33 females, 1-7 years of age) with fewer than 2 spontaneous bowel movements per week for at least one month completed the study. After 1 week of therapy, a good response, defined as 3 or more bowel movements per week, was achieved in 30 (68.2%) of children treated with cisapride and MgO compared with 23 (57.5%) children treated with MgO alone (p=n.s.). At the end of the 4-week treatment period, 90.9% of the children in cisapride group compared with 67.5% of the children in MgO group achieved a good response (p=0.013). There was no statistical difference between the two groups in terms of the side effects and stool characteristics. In conclusion, it appears that cisapride in combination with MgO may have a synergistic effect and improves the frequency of stool passage in pediatric functional constipation.

Child↗