Plasma protein(s)-based conceptual diagnostic tool for assessing high-altitude acclimation in humans.

Exposure to high altitude above 3000 m leads to two outcomes-acclimation or high-altitude maladies. To reach a particular outcome, the plasma proteome is modified differentially, either in context of an acclimation response or mal-acclimation response leading to disease. This ensures that hypoxia-responsive plasma protein trends reflect acclimation in acclimated individuals when compared with their levels prior to acclimation. Such protein trends could be used to assess acclimation in an individual and any significant deviation from this trend may indicate non-acclimation, thereby preventing high-altitude illnesses before they manifest. In this study, we investigate and statistically evaluate the trendlines of various hypoxia-responsive plasma protein levels, reported significantly perturbed in our previous studies, in individuals (male; n = 20) exposed to 3520 m at high-altitude day 1 (HAD1), HAD4, and HAD7L and to 4420 m at HAD7H, HAD30, and HAD120. We observe that thioredoxin (Trx), glutathione peroxidase 3 (GPx-3), and apolipoprotein AI (Apo-AI) are statistically robust markers to assess acclimation across the exposure duration while sulfotransferase 1A1 (ST1A1) is a capable negative control whose levels increase only in cases of HAPE. We also observe exposure day-specific and resident altitude-specific proteins capable of accurately assessing acclimation when compared with baseline levels or the lower altitude zone.

Genetic polymorphisms of sulfotransferases (SULT1A1 and SULT1A2) in a Turkish population.

Sulfotransferases (SULTs) play a significant role in the biotransformation of a variety of xenobiotics and endogenous compounds. SULTs are genetically polymorphic enzymes; to date, 12 human cytosolic SULT isoforms have been identified. This study investigated SULT1A1 and SULT1A2 gene polymorphism using a PCR-RFLP method (n = 303). The frequency of the SULT1A1*1 allele was 76.2% and SULT1A1*2 was 23.8%. The SULT1A1*3 allele could not be identified. The SULT1A2 frequencies were 69.2% (SULT1A2*1), 18.3% (SULT1A2*2), and 12.5% (SULT1A2*3). The SULT1A1 and SULT1A2 loci were in Hardy-Weinberg equilibrium (SULT1A1 χ² = 0.58, P = 0.44; SULT1A2 χ² = 7.28, P = 0.06). Linkage analysis indicated a close linkage between these two genes (χ² = 5.31, P < 0.01); therefore, the statistical hypothesis that SULT1A1 and SULT1A2 alleles are independently distributed was rejected. Additionally, a strongly positive linkage was detected between SULT1A1*2 and SULT1A2*2 alleles in this population (D' = 0.79, χ² = 33.33).

Phytoestrogens and xenoestrogens: the contribution of diet and environment to endocrine disruption.

Some endocrine disrupting compounds such as phthalates and phenols act non-genomically by inhibiting the sulfotransferase (SULT 1E1 and SULT 1A1) isoforms which inactivate estrogens by sulfonation. A range of environmental phenolic contaminants and dietary flavonoids was tested for inhibition of the human SULT 1A1, 1E1 and 2A1 isoforms. In particular, the plasticisers 4-n-octyl- and 4-n-nonyl-phenol inhibit SULT 1E1 with IC(50) values of 0.16 microM vs. 10nM estradiol while the 2-substituted chlorophenols show similar values. Flavonoids are also SULT inhibitors; tricin is a competitive inhibitor of SULT 1E1 with a K(i) of 1.5+/-0.8 nM. In a small pilot study to determine whether ingestion of soy flavonoids would affect SULT1A1 activity in vivo as well as in vitro, sulfonation of daidzein was reduced in a group of women 'at risk' of breast cancer, as compared with controls, although the SULT 1A1*1/SULT 1A1*2 allele ratio was not different. Endocrine disrupting effects in man may be multifactorial when components from both the diet and the environment act at the same point in steroid metabolism.

A case-control study investigating the role of sulfotransferase 1A1 polymorphism in head and neck cancer.

PURPOSE: Sulfotransferases (SULT) 1A1 detoxify and bio-activate a broad spectrum of substrates including xenobiotics. The SULT1A1 gene possesses a G-->A polymorphism that results in an Arg to His substitution at codon 213, with the His allele having a low activity. The purpose of this study was to evaluate whether SULT1A1 Arg213His polymorphisms are risk factors for head and neck squamous cell carcinoma (SCCHN). METHODS: A total of 124 consecutive primary SCCHN patients and 249 age- and sex-matched hospital controls were enrolled in this study. Genomic DNA was isolated from peripheral blood lymphocytes and genotyping was performed by PCR-RFLP. A comprehensive epidemiological interview was conducted on all participants to collect their lifestyle data. RESULTS: The His/His frequencies in cases and controls were 6.5% (8/123) and 3.6% (9/247), respectively (P=0.049). Multivariate logistic regression analysis showed a significant association of SCCHN and His/His genotype (OR=3.60; 95% CI=1.01-12.88). This association was stronger amongst older people, alcohol and low fruit consumers. The resulted SULT1A1 His/His genotype also associated with a higher risk of neck node positive status (OR=5.82; 95% CI=1.10-30.68). CONCLUSIONS: These preliminary findings show for the first time that the SULT1A1 His (213) allele is a possible risk factor for head and neck cancer development.

Genetic polymorphism for human platelet thermostable phenol sulfotransferase (TS PST) activity.

Platelet TS PST basal activity and thermal stability were measured in blood samples from 237 individuals in 50 nuclear families. Significant correlations were found among first degree relatives, confirming the previously reported familial aggregation of TS PST basal activity and thermal stability. Commingling analysis of basal TS PST activity provided evidence for multiple component distributions, and after transformation to remove skewness, segregation analysis supported a major gene hypothesis. For TS PST thermal stability, commingling analysis also provided evidence for multiple component distributions. However, segregation analyses were equivocal with regard to the presence of a major gene for thermal stability, since support for a major gene model depended on skewness. Bivariate commingling analysis, which examined thermal stability by simultaneously considering basal activity and activity after heating, suggested that genotypes, as defined by the inferred component distributions for TS PST activity, differ in thermal stability. A three-allele model is proposed as one hypothesis that may account for the combined results of basal activity and thermal stability. The results of this study indicate that a major gene polymorphism in conjunction with polygenic inheritance plays an important role in the regulation of both level of activity and thermal stability of this important drug-metabolizing enzyme in humans.

Physiological significance of plasma sulfoconjugated dopamine: experimental and clinical studies.

Sulfoconjugated catecholamines have been regarded simply as metabolites of free catecholamines. However, a conjugated form of the catecholamine, dopamine has recently attracted much attention because it is present at high levels in the plasma of humans and experimental animals. We carried out experimental and clinical studies to determine the physiological significance of this large amount of dopamine conjugate in the plasma. Clinical studies showed that the plasma level of dopamine sulfate decreased significantly during the acute phase of heart failure, whereas that of free dopamine increased. Moreover, the plasma level of conjugated dopamine in patients with essential hypertension was higher than that in control subjects, and being highest in patients with renal hypertension. In experimental studies, we examined the activity for deconjugating DA sulfate in homogenates of organs from dogs. The kidney and liver exhibited the highest activities, and in the heart, the activity was higher in the atrium than the ventricle. We also examined the effect of dopamine sulfate on isolated perfused rat heart. Dopamine sulfate was found to be converted to free dopamine, which was responsible for the positive inotropic action, in atrial tissue. Moreover, deconjugation of DA sulfate to the free form was accelerated by a high work lord on the heart. From these results, we conclude that the formation of dopamine sulfate plays a role in regulating the level of plasma free dopamine and that plasma dopamine sulfate may be a storage or reserve form of dopamine. Free (or active) dopamine may be formed through a deconjugation reaction when necessary.

An HPLC-ECD procedure for measuring total phenolsulfotransferase (PST) activity in human liver, platelets and blood.

The phenolsulfotransferase (PST) activity in human liver, platelets and blood was measured under saturating concentrations of the conjugating agent, 3'-phosphoadenosine-5'-phosphosulfate (PAPS). Conventional PST assays employ PAP35S at suboptimal concentrations. In addition, the sulfate conjugate formed, namely N-acetyldopamine-sulfate (NADA-sulfate) was quantified directly by high-pressure liquid chromatography cum electrochemical detection (HPLC-ECD). NADA, the biogenic amine acceptor used in this study appeared from kinetic data to be a substrate of both the P and M forms of PST when used in micromolar concentration. Two apparent Km values of 4.2 mumol/l and 22.6 mumol/l were observed. In contrast, only one apparent Km value was evident when the assay was carried out in the presence of 2,6-dichloro-4-nitrophenol (DCNP), a selective inhibitor of the P form of PST or after heat treatment under specified conditions which inactivates the M form of PST. Thus measurement of PST activity with NADA as the acceptor substrate permits the determination of total PST activity and a parallel assay with the inclusion of DCNP would distinguish the two variants of PST, both of which appear to be present in all human tissues.

Sulfation pharmacogenetics in humans.

Human tissues contain at least three well-characterized cytoplasmic sulfotransferase (ST) enzymes, thermostable (TS) and thermolabile (TL) forms of ST (PST) and dehydroepiandrosterone (DHEA) ST. Both forms of PST are expressed in an easily accessible human tissue, the blood platelet. The presence of PST in blood platelets made it possible to perform pharmacogenetic studies of these enzymes in humans. Those studied demonstrated that TS and TL PST activities in the human platelet are regulated by separate, common genetic polymorphisms. Furthermore, the platelet activity of TS, but not of TL PST is correlated with levels of this enzyme activity in other human tissues such as liver, jejunal mucosa and cerebral cortex. The pharmacogenetic strategy used to study TS and TL PST could not be applied to DHEA ST since that enzyme is not expressed in human blood elements. However, DHEA ST is expressed in the liver. When 94 samples of human hepatic biopsy tissue obtained during clinically-indicated surgery were studied, there was a 4.6-fold range of DHEA ST activity levels and a bimodal frequency distribution, with approximately 25% of the samples included in a 'high activity' subgroup. The presence of bimodality raised the possibility that human DHEA ST activity might also be regulated by a genetic polymorphism. Since a cDNA for human hepatic DHEA ST has been cloned, it will now be possible to study molecular genetic mechanisms that might be involved in the regulation of individual variation in DHEA ST activity in human hepatic tissue. Pharmacogenetic studies of ST enzymes are intended, ultimately, to determine the role of inheritance in the regulation of individual variation in the sulfate conjugation of drugs,, xenobiotics, neurotransmitters and hormones in humans.

Human platelet sulfotransferase shows seasonal rhythms.

Our study aimed to investigate the possible presence of seasonal changes in platelet phenolsulfotransferase (ST) in a group of 20 healthy, drug-free subjects of both sexes between 24 and 37 years of age. Blood samples were taken four times a year in the period immediately following the equinoxes and the solstices. The results showed that both Sts underwent seasonal changes: the lowest values were found in autumn and in winter, and the highest in the summer. A positive correlation between the two STs and the length of the photoperiod was observed in winter whereas in the spring we detected a negative correlation between the TL ST and the photoperiod length. Future studies should clarify whether platelet ST of patients with mood disorders shows a similar seasonality.

Effects of phenolic acids on human phenolsulfotransferases in relation to their antioxidant activity.

Sulfate conjugation by phenolsulfotransferase (PST) enzyme is an important process in the detoxification of xenobiotics and endogenous compounds. There are two forms of PST that are specific for the sulfation of small phenols (PST-P) and monoamines (PST-M). Phenoilc acids have been reported to have important biological and pharmacological properties and may have benefits to human health. In the present study, human platelets were used as a model to investigate the influence of 13 phenolic acids on human PST activity and to evaluate the relationship to their antioxidant activity. The results showed that chlorogenic acid, syringic acid, protocatechuic acid, vanillic acid, sinapic acid, and caffeic acid significantly (p < 0.05) inhibited the activities of both forms of PST by 21-30% at a concentration of 6.7 microM. The activity of PST-P was enhanced (p < 0.05) by p-hydroxybenzoic acid, gallic acid, gentisic acid, o-coumaric acid, p-coumaric acid, and m-coumaric acid at a concentration of 6.7 microM, whereas the activity of PST-M was enhanced by gentisic acid, gallic acid, p-hydroxybenzoic acid, and ferulic acid. The phenolic acids exhibited antioxidant activity as determined by the oxygen radical absorbance capacity (ORAC) assay and Trolox equivalent antioxidant capacity (TEAC) assay, especially gallic acid, p-hydroxybenzoic acid, gentisic acid, and coumaric acid, which had strong activity. The overall effect of phenolic acids tested on the activity of PST-P and PST-M was well correlated to their antioxidant activity of ORAC value (r = 0.71, p < 0.01; and r = 0.66, p < 0.01). These observations suggest that antioxidant phenolic acids might alter sulfate conjugation.

Correlation of phenol sulphotransferase activities in the liver and platelets of rat.

Phenol sulphotransferase (PST) activity in rat platelet cytosol for p-nitrophenol (PNP) sulphation was found to have a similar dependence on PNP concentration and thermostability to that in rat liver cytosol. The activities of PST isoenzyme for the sulphation in the microM range of PNP in rat platelets and rat liver were significantly correlated. Thus, measurement of PST activity in platelets could be a useful and practical method for predicting this activity in liver.

Consumption of Brussels sprouts protects peripheral human lymphocytes against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and oxidative DNA-damage: results of a controlled human intervention trial.

To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies are due to protection against DNA-damage, an intervention trial was conducted in which the impact of vegetable consumption on DNA-stability was monitored in lymphocytes with the comet assay. After consumption of the sprouts (300 g/p/d, n = 8), a reduction of DNA-migration (97%) induced by the heterocyclic aromatic amine 2-amino-1-methyl-6-phenyl-imidazo-[4,5-b]pyridine (PhIP) was observed whereas no effect was seen with 3-amino-1-methyl-5H-pyrido[4,3-b]-indole (Trp-P-2). This effect protection may be due to inhibition of sulfotransferase 1A1, which plays a key role in the activation of PhIP. In addition, a decrease of the endogenous formation of oxidized bases was observed and DNA-damage caused by hydrogen peroxide was significantly (39%) lower after the intervention. These effects could not be explained by induction of antioxidant enzymes glutathione peroxidase and superoxide dismutase, but in vitro experiments indicate that sprouts contain compounds, which act as direct scavengers of reactive oxygen species. Serum vitamin C levels were increased by 37% after sprout consumption but no correlations were seen between prevention of DNA-damage and individual alterations of the vitamin levels. Our study shows for the first time that sprout consumption leads to inhibition of sulfotransferases in humans and to protection against PhIP and oxidative DNA-damage.

Localization of human blood phenol sulfotransferase activities: novel detection of the thermostable enzyme in granulocytes.

Phenol sulfotransferases (PSTs) catalyze the sulfate conjugation of catecholamines and a variety of phenolic compounds. Thermolabile and thermostable forms of PST exist in human tissue. Blood component thermostable PST activities have proved useful as measures of the enzyme activities in other tissues such as the liver. The most thoroughly studied blood component is the human platelet, which contains both thermolabile and thermostable PST activities. Partial localization of PST activity in blood has been characterized only for thermolabile PST. We performed the studies reported here to define the cellular and subcellular localization of both thermolabile and thermostable PST activities in blood elements. Blood samples from four adults were pooled and aliquots for platelet studies were anticoagulated with ethylenediaminetetraacetic acid. Aliquots for studies of granulocytes, mononuclear cells, and erythrocytes were defibrinated to avoid platelet contamination and were separated through Ficoll-Hypaque gradients. Cytosol thermolabile PST activities assayed with dopamine as the substrate and expressed as a percent of the total thermolabile PST activity per milliliter of whole blood were as follows: platelets, 97%; granulocytes, 0.6%; mononuclear cells, 0.7%; and erythrocytes, 0.4%. Cytosol thermostable PST activities measured with p-nitrophenol were as follows: platelets, 77% of the total activity; granulocytes, 19%; mononuclear cells, 1.2%; and erythrocytes, 0.5%. Plasma and membrane-bound activities were less than 2.3% of total activities for each form. Because granulocyte thermostable PST was present in an amount greater than expected, it was further characterized. The Michaelis-Menten constant values for p-nitrophenol and 3'-phosphoadenosine-5'-phosphosulfate were 1.13 mumol/L and 0.6 mumol/L, respectively. The pH optimum of 6.6, a 50% inhibitory concentration for 2,6-dichloro-4-nitrophenol of 1.0 mumol/L, and retention of 56% of activity after preincubation at 45 degrees C for 15 minutes were the same for the granulocytes as for platelet thermostable PST. In summary, our study confirms and extends our knowledge of localization of blood thermolabile PST. Our data define for the first time the localization of blood thermostable PST and highlight the substantial contribution of granulocyte thermostable PST activity. Granulocytes represent an easily obtained nucleated cell for the study of human thermostable PST.

Platelet phenolsulphotransferase activity and 'abdominal migraine'.

Low platelet phenolsulphotransferase activity has been reported in adult patients with dietary sensitive migraine. Platelet activity of this enzyme was therefore measured in children having 'abdominal migraine' with probable dietary trigger and in controls. No significant difference was found in activity between the two groups. There was no significant correlation between platelet phenolsulphotransferase activity and age.

Human platelet thermostable phenol sulfotransferase from blacks and whites: biochemical properties and variations in thermal stability.

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and of phenolic drugs. Human platelet PST exists in at least a thermolabile form (TL PST) and a thermostable form (TS PST). The mean basal level of platelet TS PST activity in samples from American blacks is significantly higher than the basal activity in samples from whites. We carried out the studies reported here to determine whether the higher basal TS PST activity in platelet homogenates from blacks was biochemically similar to the lower basal activity in samples from whites. We also characterized variations in TS PST thermal stability. Platelet TS PST activities in samples from the two groups were almost identical with respect to pH optima, Michaelis-Menten constant values for substrates, and susceptibilities to inhibition by 2,6-dichloro-4-nitrophenol and sodium chloride. Thermolabile and thermostable TS PST were present in samples from both blacks and whites. Thermal stabilities of TS PST in samples from 167 volunteers (104 blacks, 63 whites) were expressed as heated sample-to-control sample ratios. Bimodal frequency distribution histograms of the heated-to-control ratios revealed subgroups of samples with thermolabile TS PST activities from 13.5% of blacks (heated-to-control ratio less than 0.32) and 12.7% of whites (heated-to-control ratio less than 0.27). The mean heated-to-control ratio for thermostable TS PST from blacks was significantly higher than that from whites (0.52 +/- 0.01 vs 0.43 +/- 0.01, respectively, mean +/- SEM; p less than 0.0001). Our studies demonstrated the similarity of biochemical properties of platelet TS PST at the extremes of basal activity. They also showed equivalent subgroups of blacks and whites with thermolabile TS PST. The results are an important initial step toward testing the hypothesis that inheritance may be one factor in the regulation of basal levels of activities and thermal stabilities of platelet TS PST from American blacks.

Gender-related seasonality of human platelet phenolsulfotransferase activity.

This study focused on the investigation of the possible effect of gender and season on the activity of the thermolabile and thermostable forms of platelet phenolsulfotransferase (PST) in a group of 23 healthy, drug-free volunteers of both sexes. The results showed a different seasonal profile of PST activity in men and women: in men, PST seasonal rhythms revealed a shallow profile with higher values in both the spring and summer than in the autumn. Conversely, in women, the PST seasonality showed a profile consisting overall of a main peak in the summer. Also, significant gender-dependent correlations were found between the photoperiod length and PST values. Our findings should stimulate further investigation into gender-dependent molecular mechanisms underlying the regulation of the metabolism of endogenous and xenobiotic agents, such as monoamines and phenols, which are the substrates of PST.

Interethnic and interindividual variabilities of platelet sulfotransferases activity in Italians and Finns.

OBJECTIVE: The aim of this investigation was to see whether there was interethnic variability in the platelet activities of catechol- and phenol sulfotransferases in Italians and Finns. METHODS: The activities of catechol- and phenol sulfotransferases were measured in platelets obtained from 103 Italian and 74 Finnish individuals. Blood donors were obtained from healthy volunteers free from drugs and without apparent disease. The activities of catechol- and phenol sulfotransferases were measured with 60 microM dopamine and 4 microM 4-nitrophenol as substrates, respectively. RESULTS: The activity of catechol sulfotransferase was not gender dependent and the median estimates (pmol/min/mg) were 9.10 in Italians and 6.37 in Finns (P = 0.0018). The activity of phenol sulfotransferase activity was gender dependent in Finns but not in Italians. The median estimates (pmol/min/mg) were 3.81 in Finnish men and 1.18 in Finnish women (P = 0.0007). In Italian men and women, the median estimates (pmol/min/mg) of phenol sulfotransferase activity were 1.25 and 1.24, respectively (NS). CONCLUSION: This study shows that platelet catechol sulfotransferase activity is greater in Italians than Finns and that the activity of phenol sulfotransferase is gender regulated in Finns but not in Italians. Thus, interethnic differences exist in platelet sulfotransferases between Italians and Finns.

Dietary modulation of human platelet phenolsulphotransferase activity.

1. The mammalian phenolsulphotransferase enzymes are known to play a major role in both the detoxification and possibly the activation of pre-carcinogenic phenols and aromatic amines. 2. Vegetable cytosol preparations were tested in vitro for their ability to affect the sulphation of two reference compounds (rho-nitrophenol and dopamine, which are selective substrates for the phenol and monoamine forms of phenolsulphotransferase respectively), and to act as substrates for the enzymes in comparison with the same reference compounds. 3. The majority of cytosols greatly decreased (> 80%) the sulphation of either or both the reference compounds. This effect may have been due to either enzyme inhibition or substrate binding. 4. Whereas some of the cytosols were sulphated under the assay conditions, most were not. Additionally, it was found that a cytosol that decreased the sulphation of the two reference compounds was not necessarily poorly sulphated itself. 5. It is concluded that dietary factors have the potential to play a major role in modulating the sulphation detoxification pathway, and have wide ranging implications with regard to adverse drug reactions.

Platelet sulphotransferase activity, plasma sulphate levels and sulphation capacity in patients with migraine and tension headache.

Activity of both the M- and P-forms of sulphotransferase (ST) was measured in platelets from patients with migraine, tension headache and controls. Mean PST values were 0.065 +/- 0.023 and 0.057 +/- 0.052 nmol/mg protein/min for migraine patients with and without aura. The corresponding values for tension headache and controls were 0.122 +/- 0.059 and 0.127 +/- 0.093 nmol/mg protein/min respectively (p < 0.05). Mean MST values were not different for any of the groups, and MST and PST activities measured in two patients during a migraine attack were not significantly altered from baseline levels. Mean plasma inorganic sulphate concentrations and paracetamol metabolites were not significantly different in any of the groups studied. The results suggest that PST activity may be a factor in the aetiology of migraine.