New insights into vitamin D regulation: is there a role for alkaline phosphatase?

PURPOSE: The diagnosis of vitamin D deficiency is based on the determination of total plasma 25-hydroxyvitamin D (25-OHD) concentrations, but the regulation of vitamin D 25-hydroxylation is not a major consideration and very little information is available on this activity. To check what factors could interfere with the activity of vitamin D-25-hydroxylase and thus alter the 25-OHD concentrations, we looked for potential correlations between 25-OHD and results of liver function tests in healthy adults. METHODS: This single-centre study was retrospective and consisted of evaluating the correlations between 25-OHD and the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and bone alkaline phosphatase (BALP) in 349 healthy subjects aged from 18 to 65 years. In particular, in Group 1 (n = 119), we looked for correlations between 25OHD and all liver function tests and in Group 2 (n = 230) the correlation between 25OHD and BALP. RESULTS: In Group 1, we found no correlation between 25OHD and AST (r = - 0.03; p = 0.8), ALT (r = - 0.02; p = 0.91), GGT (r = - 0.08; p = 0.68), direct bilirubin (r = - 0.02; p = 0.89), indirect bilirubin (r = - 0.24; p = 0.21), and total bilirubin (r = - 0.24; p = 0.21) but one between 25OHD and ALP (r = - 0.2; p = 0.007); in Group 2, we found a significant negative correlation between 25-OHD and BALP (r = - 0.2; p = 0.0008). CONCLUSIONS: The correlations that we found suggest that ALP and BALP might be involved in the regulation of vitamin D-25-hydroxylase activity, but further studies are mandatory to confirm our assumptions.

Anaphylaxis during the first course of high-dose methotrexate: a case report and literature review.

WHAT IS KNOWN AND OBJECTIVE: Methotrexate (MTX) is widely used in the management of paediatric cancer with a generally favourable benefit/risk profile. We report an unusual adverse drug reaction with the first course of high-dose MTX in a paediatric patient and review the literature for similar cases. CASE SUMMARY: An 11-year-old boy with small-cell osteoblastic osteosarcoma in the lower limb experienced a case of life-threatening anaphylaxis during the first course of high-dose MTX. The adverse event occurred during the first course, likely due to an immune-mediated mechanism. We postulate that prior antineoplastic treatment might have contributed to the immune response to MTX. WHAT IS NEW AND CONCLUSION: Given that this reaction has rarely been reported, we discuss the present case with a review of other similar cases. Further studies are needed to substantiate this 'signal alarm' for serious MTX-related hypersensitivity reactions.

Potential drug-drug interactions and radiodiagnostic procedures: an in-hospital survey.

OBJECTIVES: To evaluate the type, frequency, severity and predictors of potential Drug-Drug Interactions (DDIs) in a cohort of patients undergoing radiodiagnostic procedures. SETTING: Eight Radiology wards located in Tuscany (Italy). METHODS: All participants exposed to at least two medications were included in the analysis. DDIs were grouped according to their severity as 'minor', 'moderate' or 'major'. A logistic model was used to estimate Odds Ratios and 95% Confidence Intervals for all predictors of potential DDI. MAIN OUTCOME MEASURES: Type and predictors of potential DDI in a cohort of patients undergoing radiodiagnostic procedures. RESULTS: One-thousand-and-two subjects (57.6% females; mean age: 67.3 +/- 12.2) entered the analysis, and 46.1% of them incurred in a potential DDI (78.9% 'moderate' in severity). The combination of allopurinol and ACE-inhibitors was the most frequent (21/153) among major potential DDIs, while steroids were involved in all cases of potential DDI due to premedication. Co-morbidity, number of co-medications, advanced age and premedication use increased the risk of potential DDI; a protective role was found for positive history of allergy. When the analysis was restricted to subjects with premedication (n = 93), only 12.9% of them reported a potential DDI directly attributable to premedication drugs. CONCLUSIONS: Among patients undergoing radiological examination, types and predictors of potential DDIs appeared in agreement with other kind of in-hospital populations. Premedication revealed to be a proxy predictor for potential DDIs. Considering the poor capability of the prescriber in recognizing interactions, their systematic evaluation (using an informatics tool) in patients undergoing radiological examination might be helpful in preventing the occurrence of clinically relevant DDIs.

Interleukin-20 circulating levels in obese women: effect of weight loss.

BACKGROUND AND AIMS: Obesity is associated with an increased risk of developing atherosclerosis. Interleukin-20 (IL-20) is a pleiotropic cytokine thought to be involved in the onset and progression of atherosclerosis. The aim of this study was to determine whether circulating levels of IL-20 are elevated in obese women and whether they could be affected by a substantial decrease in body weight. METHODS AND RESULTS: Fifty obese and 50 age-matched, normal weight, premenopausal women participated in the study. Obese women entered into a medically supervised weight loss program aimed at reducing body weight to 90% of baseline. We measured anthropometric, glucose and lipid parameters, and IL-20, C-Reactive Protein (CRP) and interleukin-10 (IL-10) circulating levels. Circulating IL-20 and CRP levels were significantly higher in obese than control women (P=0.01), while IL-10 levels were significantly lower; IL-20 levels were positively associated with body weight (r=0.35; P=0.02) and visceral fat (waist-hip ratio; r=0.32; P=0.025). Caloric restriction-induced weight loss (>10% of original weight) over 6 months reduced IL-20 levels from 152 (112/184) to 134 (125/153)pg/ml (median and 25%/75%; P=0.03), and it was positively associated with changes in body mass index and waist-hip ratio. CONCLUSION: In premenopausal obese women, IL-20 levels are higher than matched normal weight control women, are associated with body weight and waist-hip ratio, and are reduced by weight loss.

Diabetic rat testes: morphological and functional alterations.

Reproductive dysfunction is a consequence of diabetes, but the underlying mechanisms are poorly understood. This study investigated the histological and molecular alterations in the testes of rats injected with streptozotocin at prepuperal (SPI rats) and adult age (SAI rats) to understand whether diabetes affects testicular tissue with different severity depending on the age in which this pathological condition starts. The testes of diabetic animals showed frequent abnormal histology, and seminiferous epithelium cytoarchitecture appeared altered as well as the occludin distribution pattern. The early occurrence of diabetes increased the percentage of animals with high number of damaged tubules. The interstitial compartment of the testes was clearly hypertrophic in several portions of the organs both in SPI and SAI rats. Interestingly, fully developed Leydig cells were present in all the treated animals although abnormally distributed. Besides the above-described damages, we found a similar decrease in plasma testosterone levels both in SPI and SAI rats. Oxidative stress (OS) is involved in the pathogenesis of various diabetic complications, and in our experimental models we found that manganese superoxide dismutase was reduced in diabetic animals. We conclude that in STZ-induced diabetes, the altered spermatogenesis, more severe in SPI animals, is possibly due to the effect of OS on Leydig cell function which could cause the testosterone decrease responsible for the alterations found in the seminiferous epithelium of diabetic animals.

Mediterranean diet improves sexual function in women with the metabolic syndrome.

In the present study, we tested the effect of a Mediterranean-style diet on sexual function in women with the metabolic syndrome. Women were identified in our database of subjects participating in controlled trials evaluating the effect of lifestyle changes and were included if they had a diagnosis of female sexual dysfunction (FSD) associated with a diagnosis of metabolic syndrome, a complete follow-up in the study trial and an intervention focused mainly on dietary changes. Fifty-nine women met the inclusion/exclusion criteria; 31 out of them were assigned to the Mediterranean-style diet and 28 to the control diet. After 2 years, women on the Mediterranean diet consumed more fruits, vegetables, nuts, whole grain and olive oil as compared with the women on the control diet. Female sexual function index (FSFI) improved in the intervention group, from a mean basal value of 19.7+/-3.1 to a mean post-treatment value of 26.1+/-4.1 (P=0.01), and remained stable in the control group. C-reactive protein (CRP) levels were significantly reduced in the intervention group (P<0.02). No single sexual domain (desire, arousal, lubrication, orgasm, satisfaction, pain) was significantly ameliorated by the dietary treatment, suggesting that the whole female sexuality may find benefit from lifestyle changes. A Mediterranean-style diet might be effective in ameliorating sexual function in women with metabolic syndrome.

Curcumin is a potent inhibitor of phenol sulfotransferase (SULT1A1) in human liver and extrahepatic tissues.

1. Curcumin has anti-carcinogen effects and is under clinical evaluation as a potential colon cancer chemopreventive agent. The first aim was to see whether curcumin inhibited phenol sulfotransferase (SULT1A1) and, if so, to study the variability of the IC(50) of curcumin for SULT1A1 in 50 human liver samples. For comparative purposes, the inhibition of catechol sulfotransferase (SULT1A3) in five human liver specimens was studied. The second aim was to measure the IC(50) of curcumin against SULT1A1 in five samples of human duodenum, colon, kidney and lung. 2. Curcumin was a potent inhibitor of SULT1A1 in human liver; the mean +/- SD and median of IC(50) were 14.1 +/- 7.3 nM and 12.8 nM, respectively. The IC(50) ranged from 6.2 to 30.6 nM between the 5th and 95th percentiles and the fold of variation was 4.9. The distribution of IC(50) was positively skewed (skewness 1.2) and deviated from normality (p = 0.0004). 3. Curcumin inhibited human SULT1A3, and the inhibition was studied in five liver specimens with an IC(50) of 4324 +/- 1026 nM. This inhibition was greater than the IC(50) of curcumin for SULT1A1 (p < 0.0001). 4. In the extrahepatic tissues, the IC(50) of curcumin for SULT1A1 was 25.9 +/- 4.8 nM (duodenum), 25.4 +/- 6.8 nM (colon), 23.4 +/- 2.2 nM (kidney) and 25.6 +/- 5.6 nM (lung). Inhibition in these tissues is greater than that of curcumin for SULT1A1 in human liver (p < 0.0001). 5. In conclusion, curcumin is a potent inhibitor of SULT1A1 in human liver, duodenum, colon, kidney and lung. The IC(50) of curcumin for SULT1A1 varied 4.9-fold in human liver. The comparison of the present data with those of the literature revealed that the IC(50) of curcumin in the liver and extrahepatic tissues is one order of magnitude lower that the peak serum concentration of curcumin after therapeutic doses of 4 g to humans.

Quercetin inhibits the sulfation of r(-)-apomorphine in human brain.

The first aim of this investigation was to study the sulfation of R(-)-apomorphine in human brain. The second aim was to investigate the inhibition of R(-)-apomorphine sulfation by quercetin in human brain. R(-)-apomorphine is hereafter referred to as apomorphine. Apomorphine sulfation was measured in 5 brain specimens; 3 derived from the frontal cortex and 2 derived from the temporal cortex. The rate of apomorphine sulfation was 5.6 +/- 4.3 pmol/min/mg. The activities of SULT1A1 and SULT1A3, which were also measured in these samples, were 11 +/- 9.1 and 2.6 +/- 1.7 pmol/min/mg, respectively. The rate of apomorphine sulfation correlated with the activity of SULT1A1 (r = 0.989; p = 0.002) and SULT1A3 (r = 0.973; p = 0.005). Apomorphine sulfotransferase followed Michaelis-Menten kinetics, the Km (mean +/- SD) and Vmax values (mean +/- SD) of which, measured in 5 brain samples, were 32 +/- 7.3 microM and 8.9 +/- 7.9 pmol/min/mg, respectively. Quercetin was a potent inhibitor of apomorphine sulfation with an IC50 value, measured in 5 brain samples, of 16 +/- 2.3 nM. The inhibition mechanism of quercetin using apomorphine sulfation in 5 brain samples was mixed, non-competitive with a Ki and Kies (mean +/- SD) of 16 +/- 4.1 and 87 +/- 37 nM, respectively (p = 0.008). The intrinsic clearance value of apomorphine (mean +/- SD) was 247 +/- 170 ml/min/mg(-1) and was decreased to 100 +/- 85 ml/min/mg(-1) (p < 0.01) in the presence of 25 nM quercetin. In conclusion, apomorphine is sulfated in human brain. Sulfation might reduce the level of apomorphine in human brain and be a factor limiting the effect of this drug. Quercetin is a potent inhibitor of apomorphine sulfation and may inhibit the sulfation of apomorphine in human brain in vivo.

7-OH-flavone is sulfated in the human liver and duodenum, whereas 5-OH-flavone and 3-OH-flavone are potent inhibitors of SULT1A1 activity and 7-OH-flavone sulfation rate.

1. The aim of this investigation was to see whether 7-OH-flavone, 5-OH-flavone and 3-OH-flavone, which are present in edible vegetables, fruit and wine, are substrates or inhibitors of human liver and duodenum sulfotransferase. 2. An assay was set up to study the sulfation of 7-OH-flavone, and using this assay, it was observed that 7-OH-flavone was sulfated and the rate of sulfation (mean +/- SD) was 324 +/- 87 pmol min(-1) mg(-1) (liver) and 584 +/- 164 pmol min(-1) mg(-1) (duodenum; p < 0.0001). 3. 7-OH-flavone sulfotransferase followed Michaelis-Menten kinetics and the K(m) (mean +/- SD) was 0.2 +/- 0.04 microM (liver) and 1.1 +/- 0.3 microM (duodenum; p = 0.008). V(max) (mean +/- SD) was 392 +/- 134 pmol min(-1) mg(-1) (liver) and 815 +/- 233 pmol min(-1) mg(-1) (duodenum; p = 0.016). 4. 5-OH-flavone and 3-OH-flavone were not sulfated and were inhibitors of human liver and duodenum SULT1A1 activity and 7-OH-flavone sulfation rate. 5. The IC50 of 5-OH-flavone for SULT1A1 was 0.3 +/- 0.06 microM (liver) and 0.3 +/- 0.1 microM (duodenum; n.s.) and those of 3-OH-flavone were 1.0 +/- 0.1 microM (liver) and 1.6 +/- 0.03 microM (duodenum; p = 0.0006). 6. There was inhibition of 7-OH-flavone sulfation rate by 5-OH-flavone and 3-OH-flavone. The IC(50) of 5-OH-flavone for the sulfation rate of 7-OH-flavone was 3.5 +/- 0.5 microM (liver) and 69 +/- 18 microM (duodenum; p < 0.0001) and for 3-OH-flavone it was 18 +/- 3.4 microM (liver) and 213 +/- 47 microM (duodenum; p < 0.0001). 7. The position of the hydroxy group confers to the molecules of OH-flavones the quality of substrate or inhibitor of sulfotransferase.

Sulfation of R(-)-apomorphine in the human liver and duodenum, and its inhibition by mefenamic acid, salicylic acid and quercetin.

1. The aims were to study the sulfation of R-(-)-apomorphine (hereafter apomorphine) in the human liver and duodenum, and to study the rate of inhibition of apomorphine sulphation by mefenamic acid, salicylic acid and quercetin also in the human liver and duodenum. 2. A rapid and sensitive method was developed to measure the sulfation rate of apomorphine in the human liver and duodenum. The method was based on the use of 0.4 micro M 3'-phosphoadenosine-5'-phosphosulfate-[(35)S] (PAPS) and 50 micro M apomorphine. The unreacted PAPS was precipitated with barium hydroxide, barium acetate and zinc sulfate. 3. The rate of apomorphine sulfation (mean +/- SD and median) was 261 +/- 82 and 242 pmol min(-1) mg(-1), respectively (liver), and 433 +/- 157 and 443 pmol min(-1) mg(-1), respectively (duodenum). The apomorphine sulfation rate was higher in the duodenum than in the liver (p = 0.0005). 4. Apomorphine sulfation was correlated with SULT1A1 activity in the liver (r(2) = 0.363, p = 0.005) and duodenum (r(2) = 0.494, p = 0.0005), but it did not correlate with SULT1A3 activity both in the liver and duodenum. 5. The K(m) estimate of apomorphine sulfation rate was 20 +/- 3.6 (liver) and 6.5 +/- 0.2 microM (duodenum, p = 0.024), and the V(max) estimate was 248 +/- 99 (liver) and 636 +/- 104 pmol min(-1) mg(-1) (duodenum, p = 0.018). 6. Mefenamic acid, salicylic acid and quercetin were potent inhibitors of apomorphine sulfation rate in the liver, and the IC(50) estimates were 16 +/- 0.2 nM, 54 +/- 8.6 microM and 18 +/- 2.8 nM, respectively. These compounds were poor inhibitors of apomorphine sulfation in the duodenum. 7. Apomorphine is sulfated by the human liver and duodenum, the highest activity being associated with the duodenum. The K(m) of apomorphine sulfotransferase is in the order of micro M both in the liver and duodenum. The non-steroidal anti-inflammatory drug mefenamic acid and the natural flavonoid quercetin inhibit the hepatic sulfation of apomorphine with an IC(50) in the order of nM.

Inhibition of mycophenolic acid glucuronidation by niflumic acid in human liver microsomes.

OBJECTIVES: The first aim of this investigation was to study the variability of mycophenolic acid (MPA) glucuronidation rate in human liver. The second aim was to study the inhibition type of niflumic acid (NA) for MPA glucuronidation in human liver. The third aim was to study the variability of the IC(50) value of NA for MPA glucuronidation in human liver. METHODS: The rate of MPA glucuronidation was measured by employing an assay based on uridine 5'-diphosphate-[U-(14)C]-glucuronic acid (UDPGA), and MPA glucuronide was isolated by means of thin-layer chromatography. The necessary concentration for UDPGA and MPA was 1 mM. The rate of MPA glucuronidation was measured in 50 human liver samples. The inhibition type of NA for MPA glucuronidation was studied in 5 human liver samples. The NA IC(50) value was measured in 27 human liver samples using six concentrations of NA ranging from 1.05 microM to 34 microM. RESULTS: MPA glucuronidation rate was positively skewed, was not gender regulated and did not correlate with the liver donor's age. The rate of MPA glucuronidation varied 4.8-fold within the 5th and 95th percentiles, with a mean+/-SD and a median of 2.8+/-1.0 nmol/min/mg and 2.5 nmol/min/mg, respectively. The inhibition type of NA for MPA glucuronidation was mixed non-competitive. The Ki value of NA (mean+/-SD) was 15+/-10 microM and, in non-inhibited samples, the K(m) value for MPA was 0.41+/-0.06 mM. The distribution of NA IC(50) value varied 3.3-fold within the 5th and 95th percentiles with a mean+/-SD and a median of 5.6+/-2.1 microM and 5.2 microM, respectively. The distribution of NA IC(50) value did not deviate significantly from normality. CONCLUSION: The range of hepatic rate of MPA glucuronidation is narrow relative to those of ethinyloestradiol, testosterone and zidovudine glucuronidation obtained from literature. The Ki value of NA is one order of magnitude lower than the K(m) for MPA in non-inhibited samples. This indicates that the inhibitor affinity for glucuronosyl transferase is greater than that of the substrate. The range of variation of NA IC(50) values is narrow.

Serum anti-p53 antibodies in lung cancer: comparison with established tumor markers.

As reported earlier, p53 antibodies are detected in the sera of patients with different types of cancer, including lung cancer. In contrast, in the serum of healthy subjects the presence of anti-p53 antibodies is extremely rare. We collected the venous blood samples of 109 patients affected with lung cancer (LC): 57 patients (46 M, 11 F) with non-small-cell carcinoma (NSCLC), 52 others (40 M, 12 F) with small-cell carcinoma (SCLC). Serum p53 antibodies were assayed using ELISA method and all positive sera were confirmed by Western-blot method. In addition, using IRMA methods we assayed serum CEA, TPA, CYFRA21-1 and NSE. Serum p53Ab are detectable (p53Ab-positive) in 35/109 (32.1%) patients with lung cancer. About 17/57 (29.8%) patients affected with NSCLC and 18/52 (34.6%) with SCLC were p53Ab-positive. CEA, TPA, CYFRA21-1 and NSE sensitivity in LC patients (NSCLC+SCLC) is 50.5%, 58.7%, 42.2%, 35.8%, respectively. The lower sensitivity (32.1%) of serum p53Ab is connected with the higher specificity and diagnostic accuracy (100% and 69%, respectively). Out of 35 patients p53Ab-positive, five (14.3%) exhibit only serum p53Ab, while serum values of the established tumor markers were lower than cut-off. Serum p53Ab assessment is a simple and a low-cost assay with a good specificity and diagnostic accuracy that in LC patients can be used at least in association with established tumor markers.

Human adult and foetal liver sulphotransferases: inhibition by mefenamic acid and salicylic acid.

1. The aim was to see whether mefenamic acid and salicylic acid had different inhibition profiles for SULT1A1 (substrate: 4-nitrophenol) and SULT1A3 (dopamine) activities and on (-)-salbutamol and minoxidil sulphation rates in the human adult and mid-gestational foetal livers. 2. The activity (pmolmin(-1) mg(-1) of SULT1A1 was 662 +/- 78 (adult) and 246 +/- 159 (foetus; p = 0.003) and that of SULT1A3 was 24 +/- 4 (adult) and 121 +/- 90 (foetus; p = 0.030). The rate (pmol min(-1) mg(-1)) of (-)-salbutamol sulphation was 109 +/- 27 (adult) and 117 +/- 34 (foetus; p = (0.144) and that of minoxidil sulphation was 202 +/- 38 (adult) and 108 +/- 44 (foetus; p = 0.001). 3. With mefenamic acid as an inhibitor, the IC50 (microM) for SULT1A1 was 0.2 +/- 0.004 (adult) and 0.01 +/- 0.002 (foetus; p = 0.001); for SULT1A3 it was 76 +/- 6 (adult) and 77 +/- 13 (foetus; p = 0.889); for the rate of ( )-salbutamol sulphation it was 0.07 +/- 0.005 (adult) and not determinable (foetus) and for minoxidil sulphation it was 1.6 +/- 0.7 (adult) and 0.15 +/- 0.04 (foetus; p = 0.076). 4. With salicylic acid as an inhibitor, the IC50 (microM) for SULT1A1 was 30 +/- 2 (adult) and 25 +/- 1 (foetus; p = 0.011); for SULT1A3 it was 690 +/- 36 (adult) and 570 +/- 16 (foetus; p = 0.229); for the rate of ( )-salbutamol sulphation it was 93 +/- 11 (adult) and 344 +/- 42 (foetus; p = 0.010); with minoxidil as substrate, the IC50 was not determinable. 5. In summary, SULT1A1, SULT1A3 and the sulphotransferases towards (-)-salbutamol and minoxidil had measurable activities in the mid-gestational human foetal liver. Mefenamic acid was a more potent inhibitor than salicylic acid of both human adult and foetal liver SULT1A1 and SULT1A3 activities. Foetal liver SULT1A1 was more susceptible than adult liver SULT1A1 to inhibition by mefenamic acid and salicylic acid. These results are consistent with the view that sulphotransferases develop early in the human foetal liver and drugs may inhibit their activities.

Serum concentration of free T3, free T4 and TSH in healthy children.

OBJECTIVE: It is rare that manufacturers report age-related FT3, FT4 and TSH normal ranges in healthy children. STUDY DESIGN: Using a solid phase time-resolved fluoroimmunometric method, we determined serum FT3, FT4 and TSH in 3,360 healthy children, age 2-16 years, that we grouped into two age ranges (2-7 yr and 9-16 yr). RESULTS: Boys' and girls' mean serum thyroid hormone values substantially overlap in all age groups. In the age range 2-7 yr, FT3, FT4 and TSH values were 0.10-0.67 ng/dl (mean 0.37 ng/dl), range 0.45-2.29 ng/dl (mean 1.18 ng/dl) and 0.10-5.9 microU/ml (mean 2.2 microU/ml), respectively. In the age range 9-16 yr, FT3, FT4 and TSH values were 0.11-0.53 ng/dl (mean 0.35 ng/dl), 0.69-1.69 ng/dl (mean 1.07 ng/dl) and 0.20-6.1 microU/ml (mean 2.3 pU/ml), respectively. CONCLUSION: Our results represent a useful set of reference values in children and can help physicians in the management of thyroid diseases.

Differential inhibition of human liver and duodenum sulphotransferase activities by quercetin, a flavonoid present in vegetables, fruit and wine.

1. Quercetin is a natural flavonoid present in vegetables, fruit and wine, and is known to inhibit sulphotransferase. Drugs are often taken orally and the intestinal mucosa is an early site of drug metabolism. The aims of this investigation were to study the inhibition of dopamine, (-)-salbutamol, minoxidil and paracetamol sulphation by quercetin in the duodenal mucosa and liver and to compare the IC50 in these tissues. 2. The rates (pmol min(-1) mg(-1)) of sulphation of 4-nitrophenol were 343+/-92 (liver) and 164+/-22 (duodenum; p = 0.031), of dopamine were 15+/-11 (liver) and 656+/-516 (duodenum; p = 0.049), of (-)-salbutamol 153+/-31 (liver) and 654+/-277 (duodenum; p = 0.018), of minoxidil were 156+/-47 (liver) and 105+/-7 (duodenum; n.s.), and of paracetamol were 229+/-86 (liver) and 328+/-187 (duodenum; n.s.). 3. The IC50 of quercetin for 4-nitrophenol was 48+/-11 nM (liver) and 56+/-1 nM (duodenum, n.s.), for dopamine was 5.7+/-0.7 microM (liver) and 170+/-12 microM (duodenum, p < 0.0001), for (-)-salbutamol was 54+/-4 nM (liver) and 16+/-8 microM (duodenum; p = 0.025), for minoxidil was 134+/-22 nM (liver) and 3+/-0.3 microM (duodenum, p = 0.013), and for paracetamol was 57+/-7 nM (liver) and 35+/-1 microM (duodenum; p = 0.0002). 4. Quercetin inhibited the sulphation of 4-nitrophenol, dopamine, (-)-salbutamol, minoxidil and paracetamol both in liver and duodenum. With dopamine, (-)-salbutamol, minoxidil and paracetamol as substrates, quercetin was a more potent inhibitor in the liver than the duodenum. Such a difference may reflect the different composition of sulphotransferase forms in the liver and duodenum.

Discovery of a transient absorption edge in the X-ray spectrum of GRB 990705.

We report the discovery of a transient equivalent hydrogen column density with an absorption edge at approximately 3.8 kiloelectron volts in the spectrum of the prompt x-ray emission of gamma-ray burst (GRB) 990705. This feature can be satisfactorily modeled with a photoelectric absorption by a medium located at a redshift of approximately 0.86 and with an iron abundance of approximately 75 times the solar one. The transient behavior is attributed to the strong ionization produced in the circumburst medium by the GRB photons. The high iron abundance points to the existence of a burst environment enriched by a supernova along the line of sight. The supernova explosion is estimated to have occurred about 10 years before the burst. Our results agree with models in which GRBs originate from the collapse of very massive stars and are preceded by a supernova event.

Observation of X-ray lines from a gamma-ray burst (GRB991216): evidence of moving ejecta from the progenitor.

We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion.

Differential inhibition of hepatic and duodenal sulfation of (-)-salbutamol and minoxidil by mefenamic acid.

OBJECTIVE: The aim of this investigation was to determine whether mefenamic acid and salicylic acid inhibit the sulfation of (-)-salbutamol and minoxidil in the human liver and duodenum, and if so, to ascertain whether the 50% inhibitory concentration (IC50) estimates are different in the two tissues. METHODS: Sulfotransferase activities were measured for 10 mM (-)-salbutamol and 5 mM minoxidil, and the concentration of 3'-phosphoadenosine-5'-phosphosulphate-[35S] was 0.4 microM. RESULTS: The IC50 estimates for (-)-salbutamol and minoxidil sulfation of mefenamic acid were 72 +/- 5.4 nM and 1.5 +/- 0.6 microM (liver), respectively, and 161 + 23 microM and 420 +/- 18 microM (duodenum), respectively. The figures for the liver were significantly lower (P < 0.0001) than those for the duodenum. The IC50 estimates for (-)-salbutamol sulfation of salicylic acid were 93 +/- 11 microM (liver) and 705 +/- 19 microM (duodenum, P < 0.0001). Salicylic acid was a poor inhibitor of minoxidil sulfation. CONCLUSION: The IC50 estimates for (-)-salbutamol sulfation of mefenamic acid and salicylic acid are lower than their unbound plasma concentrations after standard dosing, suggesting that mefenamic acid and salicylic acid should inhibit the hepatic sulfation of (-)-salbutamol in vivo.

Inhibition of human liver phenol sulfotransferase by nonsteroidal anti-inflammatory drugs.

OBJECTIVE: The aim of this investigation was to study the inhibition of 11 nonsteroidal anti-inflammatory drugs (NSAIDs) on the human liver phenol sulfotransferases (HL-PST) and catechol sulfotransferase (HL-CST). METHODS: The activities of HL-PST and HL-CST were measured with 4 microM 4-nitrophenol and 60 microM dopamine (the sulfate acceptors) and 0.4 microM 3'-phosphoadenosine-5'-phosphosulfate [35S] (the sulfate donor). Samples of liver were obtained from five patients, aged 55-79 years, undergoing clinically indicated hepatectomy. The inhibition curves were constructed with at least five concentrations of the inhibitor. RESULTS: With the exception of piroxicam, NSAIDs inhibited HL-PST, and the estimates of the inhibitory concentration for 50% of responses (IC50; microM) were: 0.02 (mefenamic acid), 3.7 (diflunisal), 5.4 (nimesulide), 9.5 (diclofenac), 30 (salicylic acid), 41 (ketoprofen), 74 (indomethacin), 159 (ibuprofen), 245 (ketoralac) and 473 (naproxen). With 4-nitrophenol as the variable substrate, the inhibition of salicylic acid on HL-PST was non-competitive and the Ki and Kies were 18 microM and 21 microM (n = 5; P = 0.548), respectively. HL-CST was less susceptible than HL-PST to inhibition by NSAIDs, with only five drugs inhibiting this enzyme. The IC50 estimates for these drugs (microM) were 76 (mefenamic acid), 79 (diflunisal), 103 (indomethacin), 609 (salicylic acid) and 753 (diclofenac). CONCLUSION: The comparison of the IC50 estimates of HL-PST with the therapeutic plasma concentrations of NSAIDs corrected for the plasma unbound fraction was consistent with the view that mefenamic acid and salicylic acid, when administered at therapeutic doses, should impair the hepatic sulfation of those compounds that are substrates of phenol sulfotransferase.