Supplementation with a 9c,11t-rich conjugated linoleic acid blend shows no clear inhibitory effects on platelet function in healthy subjects at low and moderate cardiovascular risk: a randomized controlled trial

SCOPE

The 9cis,11trans-conjugated linoleic acid (9c,11t-CLA) is reported to have anti-atherogenic properties in animal models and to modulate protein expression in unstimulated human platelets in vivo. Platelet function was therefore investigated after dietary supplementation with 9c,11t-CLA enriched oil (CLA80:20) in a randomized, baseline-controlled cross-over trial.

METHODS AND RESULTS

Forty-three healthy adults at low to moderate risk of cardiovascular disease received 4 g/day of CLA80:20 or placebo for two weeks each. Platelet function, inflammation, and endothelial activation were assessed before and after each phase. Compared with placebo, supplementation had no significant effects on platelet function measured by Platelet Function Analyzer-100. Inhibitory effects on collagen-induced aggregation were sex-dependent (p = 0.005) that reached significance only in women (p = 0.045). Thrombin receptor-activating peptide (TRAP)-induced P-selectin expression was higher after supplementation in all subjects (p = 0.017). TRAP-induced platelet fibrinogen binding was also dependent on sex (p = 0.015), with fibrinogen binding after CLA80:20 being higher in males (p = 0.035). Plasma monocyte chemoattractant protein-1 was higher (p = 0.041) after CLA80:20.

CONCLUSION

No clear evidence was found for inhibition or activation of platelet function as well as inflammation by CLA80:20 in a low to moderate cardiovascular risk group.

Structure elucidation of compounds extracted from the Chinese medicinal plant Patrinia heterophylla

For several hundred years, Patrinia heterophylla has been used in traditional Chinese medicine as a treatment for abscesses, hepatitis, tonsillitis, ulcers, etc. Recent research suggests that it may also have some anti-cancer activity. We have extracted five pure compounds from this plant; two known flavonols without bio-activity, one known isocoumarin glucoside that exhibits some cytotoxic activity toward HeLa cervical cancer cells, and two novel compounds that show considerable cytotoxic activity toward HeLa cells.

Plasma leptin levels are related to body composition, sex, insulin levels and the A55V polymorphism of the UCP2 gene

OBJECTIVE

Circulating leptin levels show a high degree of individual variability even after the main effect of body fatness is accounted for. We therefore wanted to determine the roles of variation in body composition, age, sex and polymorphisms of the UCP2 gene and promoter region on levels of circulating leptin.

SUBJECTS

One hundred and fifty Caucasian subjects, which represented a cross-section of the population from NE, Scotland, were recruited.

MEASUREMENTS

Body composition was measured using dual X-ray absorptiometry. Fasted circulating leptin, insulin, T3 and T4 levels were measured, and all individuals were genotyped for the UCP2 polymorphisms A55V, -866G>A and exon-8 ins/del.

RESULTS

The results indicate that circulating leptin was significantly related to sex and principle component (PC) scores representing overall adipose tissue mass and a second representing the contrast of central to peripheral bone mineral content. Residual leptin was associated with the A55V polymorphism (P< 0.001) explaining 11.3% of the residual variance. There was a marginal effect associated with exon-8 ins/del (P=0.045) explaining 4.4% of the residual variance in leptin. Log(e) transformed circulating fasting insulin was related to PC scores representing general adiposity and sex. Residual Log(e) insulin was associated with the A55V and exon-8 ins/del polymorphisms explaining 5.7% (P=0.015) and 5% (P=0.026) of the residual variation, respectively. The -866G>A polymorphism was not significantly associated with residual leptin or insulin. Leptin and insulin were significantly (P=0.007) correlated. Statistically removing the effect of insulin on leptin still showed association between leptin and A55V (P=0.002). Removing the effect of leptin on insulin, the A55V polymorphism was no longer significant (P=0.120). After accounting for the correlation between insulin and leptin, the exon-8 ins/del was no longer significant for residual leptin (P=0.119) or Log(e) insulin (P=0.252).

CONCLUSION

These data suggest that the A55V polymorphism directly affected the levels of leptin but not via an effect on insulin.

Effects of age and dietary restriction on oxidative DNA damage, antioxidant protection and DNA repair in rats

BACKGROUND

Experimentally imposed dietary restriction is known to extend the lifespan of rodents, perhaps by slowing the accumulation of oxidative damage that is thought to be one of the causes of aging.

AIM OF THE STUDY

We examined the effects of restricted total food intake, and protein and calorie restriction, on DNA oxidation and related biomarkers in rats.

METHODS

From 1 to 17 months, rats in group 1 received normal diet ad libitum. Group 2 received 70% of the quantity consumed by the first group. Group 3 had the same quantity as group 2, but with a reduction in protein (from 18% to 10% of the diet by weight), and group 4 were further restricted with a 30% decrease in calories. Lymphocytes were isolated from blood samples taken every two months. DNA breaks, oxidised pyrimidines, resistance to H2O2-induced damage, and strand break repair were measured with the comet assay. Organs were isolated from rats killed at 17 months, with 1 month-old rats for comparison; DNA oxidation and antioxidant enzyme activities were measured.

RESULTS

DNA breaks in lymphocytes increased from 1 to 3 months but thereafter declined with age, except in ad libitum fed rats. Oxidised pyrimidines did not change significantly. Resistance to H2O2-induced damage was least at 3 months, and increased with age. Repair of DNA strand breaks was efficient at all ages. Diet had little effect on these endpoints. Diet had no influence on 8-oxo-7.8-dihydroguanine levels in DNA from liver, testis and brain of 17 month old rats. Combining data from all four groups, the levels in brain and liver were significantly higher at 17 months compared with 1 month. Antioxidant enzyme activities tended to increase between 1 and 17 months; effects of diet were not so consistent.

CONCLUSIONS

While DNA damage shows a modest increase with age in some organs, antioxidant status and DNA strand break repair do not decline with age. Restricted diets (including protein and calorie restriction) have no effect on any of these markers of genetic stability.

DNA stability and lipid peroxidation in vitamin E-deficient rats in vivo and colon cells in vitro--modulation by the dietary anthocyanin, cyanidin-3-glycoside

BACKGROUND

Fruit and vegetable consumption protects against cancer. This is attributed in part to antioxidants such as vitamin E combating oxidative DNA damage. Anthocyanins are found in significant concentrations in the human diet. However, it remains to be established whether they are bioactive in vivo.

AIM

To investigate the consequence both of vitamin E deficiency on oxidative damage to DNA and lipids and the cytoprotective effect of nutritionally relevant levels of cyanidin-3-glycoside both in vivo in rats and in vitro in human colonocytes.

METHODS

Male Rowett Hooded Lister rats were fed a diet containing less than 0.5 mg/kg vitamin E or a vitamin E supplemented control diet containing 100 mg d alpha-tocopherol acetate/kg. Half of the controls and vitamin E-deficient rats received cyanidin-3-glycoside (100 mg/kg). After 12 weeks endogenous DNA stability in rat lymphocytes (strand breaks and oxidised bases) and response to oxidative stress ex vivo (H2O2; 200 microM) was measured by single cell gel electrophoresis (SCGE). Tissue levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-Oxo-dG) were measured by HPLC with EC detection. D alpha-tocopherol and lipid peroxidation products (thiobarbituric acid reactive substances; TBARS) were measured by HPLC. Rat plasma pyruvate kinase and the production of reactive oxygen by phagocytes were detected spectrophotometrically and by flow cytometry respectively. Immortalised human colon epithelial cells (HCEC) were preincubated in vitro with the anthocyanins cyanidin and cyanidin-3-glycoside and the flavonol quercetin (all 50 microM) before exposure to H2O2 (200 microM). DNA damage was measured by SCGE as above.

RESULTS

Plasma and liver d alpha-tocopherol declined progressively over 12 weeks in rats made vitamin E deficient. Lipid peroxidation was increased significantly in plasma, liver and red cells. Reactive oxygen levels in phagocytes and plasma pyruvate kinase were increased. Vitamin E deficiency did not affect DNA stability in rat lymphocytes, liver or colon. Cyanidin-3-glycoside did not alter lipid peroxidation or DNA damage in rats. However, it was chemoprotective against DNA damage in human colonocytes.DNA strand breakage was decreased 38.8 +/- 2.2% after pretreatment with anthocyanin.

CONCLUSION

While it is accepted that vitamin E alters lipid oxidation in vivo, its role in maintaining DNA stability remains unclear. Moreover, whereas cyanidin-3-glycoside protects against oxidative DNA damage in vitro, at nutritionally relevant concentrations it is ineffective against oxidative stress in vivo.

Oxidative stress in humans: validation of biomarkers of DNA damage

Two studies have been performed to clarify the relationship between different markers of oxidative DNA damage commonly employed in molecular epidemiological studies. In the first, 8-Oxo-7,8-dihydroguanine (8-oxoGua) was induced in DNA of HeLa cells by treatment with different concentrations of photosensitizer Ro 19-8022 together with visible light. 8-OxoGua was estimated by the comet assay (alkaline single cell gel electrophoresis) with formamidopyrimidine DNA glycosylase and by HPLC with electrochemical detection. The dose-response curves indicate that the comet assay and HPLC are equally efficient at detecting induced damage. Background levels of 8-oxoGua in HeLa cells were 0.92 +/- 0.22 per 10(6) guanines by the comet assay and 2.09 +/- 0.13 per 10(6) guanines by HPLC. The second study was a small human trial, in which lymphocytes were collected for analysis of background levels of 8-oxoGua, as well as overnight and 24 h urine samples for measurement of excreted 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) by ELISA. The mean level of 8-oxoGua in lymphocytes was determined as 1.33 +/- 0.21 per 10(6) guanines by the comet assay and 3.72 +/- 1.06 per 10(6) guanines by HPLC. A strong correlation was seen between overnight and 24 h urinary 8-oxodGuo (r = 0.93, P < 0.01). Overnight urinary 8-oxodGuo concentrations correlated with 8-oxoGua in lymphocytes measured by HPLC (r = 0.85, P < 0.05) or by the comet assay (r = 0.86, P < 0.05), although individual values from HPLC and the comet assay did not correlate with each other. It is reasonable to assess oxidative stress by any of these methods.

Anthocyanin-rich extract decreases indices of lipid peroxidation and DNA damage in vitamin E-depleted rats

Anthocyanins are secondary plant metabolites responsible for the blue, purple, and red color of many plant tissues. The phenolic structure of anthocyanins conveys marked antioxidant activity in model systems via donation of electrons or hydrogen atoms from hydroxyl moieties to free radicals. Dietary intakes of anthocyanins may exceed 200 mg/day, however, little is known about their antioxidant potency in vivo. Consequently, the aim of this study was to establish whether anthocyanins could act as putative antioxidant micronutrients. Rats were maintained on vitamin E-deficient diets for 12 weeks in order to enhance susceptibility to oxidative damage and then repleted with rations containing a highly purified anthocyanin-rich extract at a concentration of 1 g/kg diet. The extract consisted of the 3-glucopyranoside forms of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Consumption of the anthocyanin-repleted diet significantly improved (p <.01) plasma antioxidant capacity and decreased (p <.001) the vitamin E deficiency-enhanced hydroperoxides and 8-Oxo-deoxyguanosine concentrations in liver. These compounds are indices of lipid peroxidation and DNA damage, respectively. Dietary consumption of anthocyanin-rich foods may contribute to overall antioxidant status, particularly in areas of habitually low vitamin E intake.

Glutathione S-transferase polymorphisms influence the level of oxidative DNA damage and antioxidant protection in humans

Glutathione S-transferase genotypes GSTT1, GSTM1, GSTP1 were characterised in 155 middle-aged men and compared with parameters of oxidative stress at the level of DNA and lipids, with antioxidant enzymes, and with plasma antioxidants in smokers and non-smokers. Smokers had on average significantly lower levels of Vitamin C, beta-carotene and beta-cryptoxanthin and higher amounts of oxidised purines and pyrimidines in lymphocyte DNA. The GSTM1 null genotype was associated with elevated glutathione as well as with higher Vitamin C concentration in plasma. Vitamin C was higher in GSTT1+ compared with GSTT1 null--as was glucose-6-phosphate dehydrogenase activity. The homozygous GSTP1 a/a genotype was associated with significantly higher levels of GST activity measured in lymphocytes, in comparison with the b/b genotype. Using multifactorial statistical analysis we found significant associations between smoking, GSTP1 genotype, plasma Vitamin C, and purine base damage in lymphocyte DNA. The difference in Vitamin C plasma levels between smokers and non-smokers was seen only with the GSTP1 b/b genotype. This group accounted also for most of the increase in purine oxidation in smokers. In contrast, the link between smoking and oxidised pyrimidines in DNA was seen only in the GSTT1 null group. It seems that polymorphisms in the phase II metabolising enzyme glutathione S-transferase may be important determinants of commonly measured biomarkers.

A gamma-aminobutyric acidB agonist reverses the negative feedback effect of testosterone on gonadotropin-releasing hormone and luteinizing hormone secretion in the male sheep

Infusion of baclofen, a GABA(B) agonist, into the medial basal hypothalamus (MBH) of castrated rams rapidly increases LH pulse amplitude without altering pulse frequency. The objectives of this study were to determine whether baclofen infusion increased LH in testosterone (T)-treated and intact rams, the increased LH was due to increased GnRH release, and FSH secretion also was increased. In the first experiment we tested the main effects and interaction of baclofen and T on FSH and LH pulse patterns in castrated rams (n = 7). In the second experiment we determined whether baclofen affected GnRH and LH pulses in intact males. Microdialysis guide cannulae were implanted bilaterally into the MBH. After recovery of the animal from surgery, the MBH was perfused using concentric microdialysis probes (2-mm tip) with artificial cerebrospinal fluid (aCSF) for a 3-h control period followed by either aCSF or 1 mM baclofen for 4 h. Blood samples were taken at 10-min intervals. T suppressed mean LH concentrations (10.4 +/- 1.3 vs. 3.3 +/- 1.3 ng/ml) such that LH pulses were undetectable in some T-treated animals during the control period. The change (control period vs. drug infusion period) in mean LH was greater in response to baclofen than in response to aCSF and was not altered by T. The baclofen x T interaction was nonsignificant. Mean FSH was decreased by T, but was not altered by baclofen. In the second experiment hypophyseal portal blood was collected coincident with microdialysis. Infusion of baclofen into the MBH of intact males (n = 7) resulted within 1 h in the onset of frequent and robust GnRH pulses (0.10/h before baclofen vs. 1.57/h after baclofen) that were followed either immediately or gradually by coincident LH pulses. One interpretation is that baclofen acts downstream of the site of action of T. GABA(B) receptors may regulate pulse amplitude in both the presence and absence of T and regulate pulse frequency by modulating the inhibitory effect of T.

Short-term treatment with alcohols causes hepatic steatosis and enhances acetaminophen hepatotoxicity in Cyp2e1(-/-) mice

CYP2E1 has been reported to have an essential role in alcohol-mediated increases in hepatic steatosis and acetaminophen hepatotoxicity. We found that pretreatment of Cyp2e1(-/-) mice with ethanol plus isopentanol, the predominant alcohols in alcoholic beverages, for 7 days resulted in micro- and macrovesicular steatosis in the livers of all mice, as well as a dramatic increase in acetaminophen hepatotoxicity. In Cyp2e1(-/-) mice administered up to 600 mg acetaminophen/kg alone and euthanized 7 h later, there was no increase in serum levels of ALT. In Cyp2e1(-/-) mice pretreated with ethanol and isopentanol, subsequent exposure to 400 or 600 mg acetaminophen/kg resulted in centrilobular necrosis in all mice with maximal elevation in serum levels of ALT. Acetaminophen-mediated liver damage was similar in males and females. Hepatic microsomal levels of APAP activation in untreated females were similar to those in males treated with the alcohols. However, the females, like the males, required pretreatment with the alcohols in order to increase APAP hepatotoxicity. These findings suggest that, in the Cyp2e1(-/-) mice, the alcohol-mediated increase in acetaminophen hepatotoxicity involves the contribution of other factors, in addition to induction of CYP(s) that activate acetaminophen. Alternatively, CYP-mediated activation of acetaminophen measured in vitro may not reflect the actual activity in vivo. Our findings that a 7-day treatment with ethanol and isopentanol causes extensive hepatic steatosis and increases acetaminophen hepatotoxicity in Cyp2e(-/-) mice indicate that CYP2E1 is not essential for either response.

The pharmacokinetics and metabolism of sucralose in the mouse

The excretion and metabolism of (14)C-sucralose has been investigated in mice following intravenous and oral administration. A 20mg/kg intravenous dose was rapidly excreted mainly in the urine (80% in 5 days). After 100, 1500 and 3000mg/kg oral doses of (14)C-sucralose, means of 23%, 15% and 16% of the dose, respectively, were excreted in the urine during 5 days. Comparison with the intravenous dose indicated that 20-30% of the oral doses was absorbed. Sucralose was excreted almost entirely unchanged and represented more than 80-90% of the radioactivity in all urine and faeces samples. Only two minor metabolites were detected, representing 2-8% of urine radioactivity.

The pharmacokinetics and metabolism of sucralose in the dog

The pharmacokinetics and metabolism of sucralose were investigated in dogs following intravenous or oral administration. Oral doses of (14)C-sucralose were rapidly absorbed, although there was some variation in the extent of absorption (range 18-48% of the dose). After intravenous or oral administration, radioactivity excreted in the urine was associated mainly with unchanged sucralose. One urinary metabolite was detected after both intravenous and oral doses and was identified by mass spectrometry as a glucuronic acid conjugate of sucralose. This metabolite accounted for about 15-20% of the intravenous dose but for only about 2-8% of the oral dose.

The pharmacokinetics and metabolism of sucralose in the rabbit

The excretion and metabolism of (14)C-sucralose has been investigated in non-pregnant and pregnant rabbits after administration of single 10mg/kg oral doses. Means of 22% and 55% of the dose were excreted in urine and faeces, respectively, by non-pregnant animals during 5 days. Excretion was similar in pregnant animals with means of 22% and 65% of the dose in urine and faeces, respectively, during the same time. Following a single oral dose, a mean of approximately 7% of the dose was still being excreted during the 96-120-hr collection period. Only one major radioactive component was detected in urine samples which corresponded to unchanged sucralose.

Thalicosides A1-A3, minor cycloartane bisdesmosides from Thalictrum minus

Three new cycloartane bisdesmosides, two of which are based on a new genin, were isolated from the above-ground parts of Thalictrum minus. Thalicosides A1-A3 (1-3) were characterized as 3-O-beta-D-galactopyranosyl-29-O-beta-D-glucopyranosyl-3beta,16beta++ +, 29-trihydroxy-22(S),25-epoxycycloartane (1); 3-O-alpha-L-arabinopyranosyl-29-O-beta-D-glucopyranosyl-3beta,1 6beta, 29,22(S)-tetrahydroxycycloart-24-ene (2); and 3-O-alpha-L-arabinopyranosyl-29-O-beta-D-glucopyranosyl-3beta,1 6beta, 29-trihydroxy-22(S),25-epoxycycloartane (3), respectively. The structural assignments of these new compounds were based on interpretation of spectroscopic data. Thalicoside A2 showed in vitro inhibition of the fungus Candida albicans and also activity against Staphylococcus aureus.

Controlled oxidation of calf thymus DNA to produce standard samples for 8-oxodeoxyguanosine analysis; effects of freeze-drying, storage and hydrolysis conditions

Calf thymus DNA containing defined levels of 8-hydroxy-2'-deoxyguanosine (8-oxodG) was prepared by treatment with visible light in the presence of photosensitiser Ro 19-8022. The DNA was checked for stability; after freeze-drying, the amount of 8-oxodG did not increase during 6 weeks' storage at room temperature. However, freeze-drying itself can introduce additional oxidative damage. Two enzymic hydrolysis regimes (DNase I, phosphodiesterases I and II, and alkaline phosphatase; or P1 nuclease and alkaline phosphatase) give similar values for 8-oxodG.

Acetaminophen hepatotoxicity precipitated by short-term treatment of rats with ethanol and isopentanol: protection by triacetyloleandomycin

Ethanol and isopentanol are the predominant alcohols in alcoholic beverages. We have reported previously that pretreatment of rats with a liquid diet containing 6.3% ethanol plus 0.5% isopentanol for 7 days results in a synergistic increase in acetaminophen hepatotoxicity, compared with rats treated with either alcohol alone. Here, we investigated the role of CYP3A in acetaminophen hepatotoxicity associated with the combined alcohol treatment. Triacetyloleandomycin, a specific inhibitor of CYP3A, protected rats pretreated with ethanol along with isopentanol from acetaminophen hepatotoxicity. At both 0.25 and 0.5 g acetaminophen/kg, triacetyloleandomycin partially prevented elevations in serum levels of alanine aminotransferase. At 0.25 g acetaminophen/kg, triacetyloleandomycin completely protected 6 of 8 rats from histologically observed liver damage, and partially protected the remaining 2 rats. At 0.5 g acetaminophen/kg, triacetyloleandomycin decreased histologically observed liver damage in 7 of 15 rats. In rats pretreated with ethanol plus isopentanol, CYP3A, measured immunohistochemically, was decreased by acetaminophen treatment. This effect was prevented by triacetyloleandomycin. These results suggest that CYP3A has a major role in acetaminophen hepatotoxicity in animals administered the combined alcohol treatment. We also found that exposure to ethanol along with 0.1% isopentanol for only 3 days resulted in maximal increases in acetaminophen hepatotoxicity by the combined alcohol treatment, suggesting that short-term consumption of alcoholic beverages rich in isopentanol may be a risk for developing liver damage from acetaminophen.

High-performance liquid chromatographic determination of quercetin and isorhamnetin in rat tissues using beta-glucuronidase and acid hydrolysis

Quercetin is a plant polyphenol which is present in the diet as an aglycone and as sugar conjugates. Despite potent vasodilatory and antioxidant effects in vitro, destruction by intestinal organisms has been assumed to limit its nutritional relevance in the rat. However, we have refined extraction techniques using beta-glucuronidase followed by acid hydrolysis. Following this with HPLC methodology with post-column derivatisation, we have detected significant concentrations of quercetin and its metabolite, isorhamnetin, in tissues of rats maintained on quercetin-rich diets. Percentage recoveries are greater than 95% and intra-batch variation does not exceed 7% suggesting that the method may be useful in further studies of the biological role of this flavonoid.

Effect of arsenite on induction of CYP1A, CYP2B, and CYP3A in primary cultures of rat hepatocytes

In earlier studies, sodium arsenite treatment was shown to decrease induction of enzymatic activities associated with hepatic CYPs in rats. Here we investigated the effect of sodium arsenite on induction of CYP2B, CYP1A, and CYP3A in primary cultures of rat hepatocytes. Arsenite decreased the induction of all three families of CYP, as measured enzymatically and immunochemically. These decreases in CYPs occurred at concentrations of arsenite (2.5-10 microM) at which no toxicity was observed; however, toxicity was observed at 25 microM arsenite. With 3-methylcholanthrene as inducer, 5 microM arsenite caused a 55% decrease in CYP1A1 immunoreactive protein and enzyme activity, but only a 25% decrease in CYP1A1 mRNA. With phenobarbital (PB) as the inducer, 2.5 microM arsenite decreased CYP2B enzyme activity and immunoreactive protein 50%, with only a 25% decrease in CYP2B1 mRNA. 5 microM Arsenite decreased CYP2B enzyme activity and immunoreactive protein 80%, but decreased CYP2B1 mRNA only 50%, while CYP3A protein was decreased greater than 75% with no decrease in CYP3A23 mRNA. With dexamethasone (DEX) as inducer, 5 microM sodium arsenite caused a 50% decrease in immunoreactive CYP3A and a 30% decrease in CYP3A23 mRNA. Although arsenite-mediated increases in heme oxygenase (HO) inversely correlated with decreases in CYP2B or CYP1A activity, inclusion of heme in cultures treated with inducers of CYP1A or CYP2B did not prevent the arsenite-mediated decreases in these CYPs. Even though added heme induced HO to similar levels with and without arsenite, decreases in CYPs were only observed in the presence of arsenite. These results suggest that, in rat hepatocytes, elevated levels of HO alone are not responsible for arsenite-mediated decreases in CYP.

Mutant yields and mutational spectra of the heterocyclic amines MeIQ and PhIP at the S1 locus of human-hamster AL cells with activation by chick embryo liver (CELC) co-cultures

Cooking meat and fish at high temperature creates heterocyclic amines (HA) including 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Several HA are mutagens in the Ames' S9/Salmonella assay. While PhIP is a substantial Ames' test mutagen, it is 1000-fold less active than the extraordinarily potent MeIQ. In contrast, MeIQ is significantly less mutagenic than PhIP in several mammalian cell assays, especially in repair-deficient Chinese hamster ovary (CHO) cells. HA are suspect human carcinogens on the basis of (i) epidemiological evidence, (ii) induction of tumors in rodents and monkeys, (iii) DNA adduct formation and (iv) mutagenic capacity. In this study, MeIQ and PhIP were significant mutagens at the S1 locus of co-cultivated human/hamster hybrid AL cells following metabolic activation by beta-napthoflavone (betaNF)-induced chick embryonic liver cultures (CELC). MeIQ was more mutagenic than PhIP in the CELC+AL cell assay. The mutant response curves increase with dose and then plateau (PhIP), or decrease (MeIQ). The inflections in these response curves coincide with dose-dependent decreases in cytochrome CYP1A1 activity. Molecular analysis of S1- mutants indicates that a substantial fraction, >65%, of the mutations induced by PhIP are deletions of 4.2 to 133 (Mbp); half are larger than 21 Mbp. Mutations induced by MeIQ were smaller, most (56%) being less than 5.7 Mbp. When appropriate metabolic activation is combined with a target locus, which can detect both small and large chromosomal mutations, both MeIQ and PhIP are significant mutagens and clastogens in repair proficient mammalian cells.

Mechanism of the synergistic induction of CYP2H by isopentanol plus ethanol: comparison to glutethimide and relation to induction of 5-aminolevulinate synthase

We had previously found that combined treatment with isopentanol and ethanol synergistically induced CYP2H protein and activity in cultured chick nepatoytes. Here we investigated the mechanism of induction of CYP2H by the alcohols and whether they caused a coordinate induction of 5-aminolevulinate synthase (ALAS) mRNA. Treatment with isopentanol alone or in combination with ethanol resulted in coordinate increases in CYP2H1 and ALAS mRNAs. With isopentanol alone, the amounts of CYP2H1 and ALAS mRNAs at 4 to 6 h were similar to those observed after treatment with the alcohol combination, but declined by 11 h. Readdition of isopentanol at 11 h again increased the expression of both mRNAs, indicating that the decreases at 11 h were due to limiting amounts of inducer. Similar results were observed in cells exposed to low concentrations of glutethimide. In the combined alcohol treatment, increases in CYP2H1 and ALAS mRNAs were sustained from 4 h to 11 h after addition of the alcohols, but decreased to control levels by 24 h. Using pulse labeling to measure de novo synthesis of CYP2H1/2 protein, we found that the increases in CYP2H1/2 protein reflected the increases in CYP2H1 mRNA. The half-life of CYP2H1/2 protein, measured from pulse-chase experiments, was approximately twofold greater than the half-life of CYP2H1 mRNA. Our results indicate that the alcohols and glutethimide coordinately increase ALAS and CYP2H1 mRNA, and that increases in CYP2H1/2 protein arise from increases in its mRNA.

Measuring oxidative damage to DNA; HPLC and the comet assay compared

Depending on the analytical method employed estimates of background levels of base oxidation in human DNA vary over orders of magnitude. It is now realised that oxidation of guanine in vitro can result in serious overestimation of the nucleoside by HPLC (with electrochemical detection). We have modified procedures of isolation, hydrolysis and storage of DNA with the aim of eliminating this artefact. Vacuum- or freeze-drying, and dialysis, tend to encourage oxidation. We compare results obtained with HPLC and with the comet assay, which employs lesion-specific enzymes to introduce breaks in DNA at sites of oxidative damage. Although estimates of background levels of DNA oxidation using the comet assay are several-fold lower than the estimates by HPLC, both approaches have been used successfully to detect differences between human subjects or population groups that seem to relate to human disease and nutritional factors.

Identification of cytochrome P450 isozymes involved in metabolism of the alpha1-adrenoceptor blocker tamsulosin in human liver microsomes

1. The in vitro human liver metabolism of the alpha1-adrenoceptor blocker tamsulosin was investigated. When 14C-tamsulosin was incubated with human liver microsomes, it was converted to five known urinary metabolites and at least three unknown metabolites. Of the former group, the predominant metabolite was the O-deethylated metabolite (M-1), followed by the o-ethoxyphenoxy acetic acid (AM-1) and the m-hydroxylated metabolite (M-3). 2. There was a good linear relationship between AM-1 formation and testosterone 6beta-hydroxylase activity in microsomes from each of 10 individual donors. The rate of M-1 formation also correlated with the same activity, albeit the correlation curve did not pass through the origin. By contrast, the rates of M-3 and the O-demethylated metabolite (M-4) formation correlated with dextromethorphan O-demethylase activity. 3. Ketoconazole strongly inhibited AM-1 formation and reduced that of M-1 by c. 60%. Immunoinhibition studies using anti-rat antibodies supported these results. The formation of M-3 and M-4 was inhibited by quinidine and sparteine. 4. It is concluded that formation of tamsulosin metabolites, AM-1 and M-1, is catalysed by CYP3A4 whereas that of M-3 and M-4 is catalysed by CYP2D6. However, minor contributions from other CYPs cannot be excluded.

Induction of cytochrome P4503A by taxol in primary cultures of human hepatocytes

In primary cultures of human hepatocytes, paclitaxel (Taxol), at pharmacological concentrations, was demonstrated to induce immunoreactive cytochrome P4503A (CYP3A). The magnitude of the inductive response of the hepatocytes to Taxol varied in five separate cultures. In general, exposure to increasing concentrations of Taxol (0.2 to 10 microM) resulted in increases in immunoreactive CYP3A. In four of the cultures, treatment of hepatocytes with the lowest concentration of Taxol tested (0.2 microM) resulted in approximately two-fold increases in CYP3A. In the other culture, however, a six-fold increase in CYP3A was observed at 0.2 microM. Taxol was almost as effective as rifampicin in inducing CYP3A in two of the cultures, but less effective than rifampicin in two other cultures. CYP3A4 mRNA was increased by Taxol. Increases in CYP3A4 mRNA correlated with increases in the levels of immunoreactive CYP3A. These results demonstrate that Taxol is a potent inducer of CYP3A in human hepatocytes. The clinical significance of these findings is discussed.

Absorption and excretion of radioactivity after intravaginal administration of an advanced delivery system of 14C-flutrimazole vaginal cream to postmenopausal women

In order to improve the effectiveness of treatment of vaginal yeast infections, flutrimazole, (CAS 119006-77-8), a broad spectrum local imidazolic fungicide, has been formulated in an advanced delivery system (Site Release, here in after briefly referred to as SR) designed to improve vaginal retention of the drug. To determine the extent of absorption of 14C-flutrimazole from this formulation, the absorption and excretion of total radioactivity have been studied in healthy postmenopausal female volunteers after intravaginal administration of approximately 5 g of SR Vaginal Cream containing 2% 14C-flutrimazole. Concentrations of unchanged flutrimazole have also been measured in plasma and urine, using a validated gas chromatography-mass spectrometry method. The rate of absorption was slow, with a mean peak plasma radioactivity concentration, Cmax, of 56 ng equivalents/ml, achieved at a mean Tmax of 28 h. Corresponding parameters for flutrimazole were 1.94 ng/ml at 24 h. At 24 h post-dose, unchanged flutrimazole represented only 3% of plasma total radioactivity which indicates that flutrimazole is extensively metabolised in man. Total radioactivity and unchanged flutrimazole were eliminated from plasma with terminal half-lives of 37 and 22 h, respectively. From the proportion of the radioactive dose excreted in urine and faeces, the maximal extent of absorption indicated for the intravaginal dose was about 8%, which is similar to that observed with other imidazolic compounds administered by this route. Thus, the formulation achieves the aim of prolonged drug action through the maintenance of therapeutic concentrations of the drug at the site of infection without notably increased absorption.

Formation of zinc protoporphyrin in cultured hepatocytes: effects of ferrochelatase inhibition, iron chelation or lead

The formation of zinc protoporphyrin in response to lead or iron depletion has previously been investigated in erythroid systems. Because of its possible metabolic role in non-erythroid tissue, we investigated the formation of zinc protoporphyrin in cultured hepatocytes. The effects of lead and inhibitors of ferrochelatase, the iron insertion step of heme synthesis, on the conversion of 5-aminolevulinic acid to zinc protoporphyrin, protoporphyrin and heme were compared in rat and chick embryo hepatocyte cultures. In rat cultures, zinc protoporphyrin was synthesized enzymatically by ferrochelatase, since N-methylmesoporphyrin, an inhibitor of ferrochelatase. caused 40% or greater decreases in both heme and zinc protoporphyrin accumulation and markedly stimulated protoporphyrin accumulation. In addition, chelation of ferrous iron with 2,2'-dipyridyl decreased heme accumulation by 50%, but increased ZPP accumulation by 200%. Zinc protoporphyrin formation in chick embryo hepatocytes required the addition of zinc as well as 5-aminolevulinic acid and apparently was non-enzymatic, since it was not inhibited by N-methylmesoporphyrin nor increased by iron chelation. In the presence of 5-aminolevulinic acid, lead had no effect on zinc protoporphyrin, protoporphyrin or heme accumulation in chick hepatocytes, but decreased all three in rat hepatocytes, with the decrease in protoporphyrin being far greater than that of zinc protoporphyrin or heme. These findings indicate that, in contrast to the effect of lead in erythroid tissue, it did not specifically increase zinc protoporphyrin accumulation or alter iron availability in cultured hepatocytes.

Absorption, metabolism and excretion after oral administration of a new Ca antagonist, 14C-benidipine hydrochloride to man

1. In healthy male volunteers, the absorption, metabolite profiles and excretion of 14C-benidipine hydrochloride, a new Ca antagonist, were investigated after oral administration at a dose of 8 mg. 2. 14C-benidipine hydrochloride was rapidly absorbed, and the plasma concentration of radioactivity and unchanged drug reached a maximum of 71.2 ng eq./ml at 1.1 h and 2.56 ng/ml at 0.6 h respectively, and then declined bi-exponentially. The half-life in the elimination phase was 14.7 and 5.3 h respectively, AUC of unchanged drug was low, about 1% of that of radioactivity. 3. Five days after administration, 36.4% of the administered radioactivity was excreted in urine and 58.9% in faeces. 4. The metabolite profiles in plasma, urine and faeces were analysed by hplc. At 1 h after administration the predominant metabolites in plasma were M9 and M2, which accounted for 13.8 and 8.2% of the radioactivity respectively, whereas unchanged drug represented 1.2%. Predominant metabolites in urine 12 h after administration were M3 and M8, which accounted for 2.22 and 2.21% of the administered radioactivity respectively. Metabolites excreted in faeces 120 h after administration were very complex and poorly separated by hplc and could not be characterized: unchanged drug was not detected in the faeces.

Role of CYP3A in ethanol-mediated increases in acetaminophen hepatotoxicity

CYP2E is considered the only form of cytochrome P450 responsible for ethanol-mediated increases in acetaminophen hepatotoxicity. However, in experimental systems used for investigating ethanol-mediated increases in acetaminophen hepatotoxicity, animals are withdrawn from ethanol for 16 to 24 hr before the administration of acetaminophen to ensure the clearance of ethanol from the circulation. In rats, CYP2E has been shown to decrease to control levels after this time period of withdrawal from ethanol. We have previously shown in cultured human and rat hepatocytes, and in intact rats, that ethanol induces CYP3A in addition to CYP2E. To determine if there might be a role for CYP3A in ethanol-mediated APAP hepatotoxicity in addition to the recognized role for CYP2E, we investigated the effect of triacetyloleandomycin (TAO) on acetaminophen hepatotoxicity in ethanol-pretreated rats, as well as the effect of 11 hr withdrawal from ethanol on hepatic levels of CYP3A and CYP2E. TAO was dissolved in saline instead of dimethylsulfoxide, the solvent most usually employed, since dimethylsulfoxide inhibits CYP2E. Rats were administered 6.3% ethanol as part of the Lieber-DeCarli diet for 7 days, followed by replacement of the liquid diet with water for 11 hr. This 11-hr withdrawal from ethanol resulted in a decrease in hepatic levels of ethanol-induced CYP2E; however, considerable induction was still evident. There was no significant decrease in CYP3A. TAO completely prevented the histologically observed liver damage from acetaminophen in ethanol-pretreated rats, but did not prevent the increase in serum levels of AST. In ethanol-pretreated rats, exposure to APAP in the absence of TAO was associated with a 75% decrease in CYP3A, compared to animals exposed to APAP in the presence of TAO. These results suggest that CYP3A may have been suicidally inactivated by acetaminophen in the absence of TAO. Our findings suggest that CYP3A has a major role in ethanol-mediated increases in acetaminophen hepatotoxicity.

Effect of Taxol on cytochrome P450 3A and acetaminophen toxicity in cultured rat hepatocytes: comparison to dexamethasone

The purpose of this study was to determine if Taxol induced CYP3A in primary cultures of rat hepatocytes and, if so, whether induction of CYP3A would increase acetaminophen toxicity. Taxol caused a concentration-dependent increase in the amount of immunoreactive CYP3A and in the steady-state levels of CYP3A1/DEX but not CYP3A2 mRNA. Similar concentration-dependent increases in toxicity as measured by a decrease in protein synthesis were observed after exposure of cells to acetaminophen for 7 hr whether cells were pretreated with Taxol or dexamethasone. Increased release of lactate dehydrogenase occured after 24 hr exposure to acetaminophen, with no further decreases in protein synthesis than those observed at 7 hr. Increases in acetaminophen toxicity correlated with increased covalent binding of acetaminophen to cellular proteins. Triacetyloleandomycin, a selective inhibitor of CYP3A, completely protected the cells against acetaminophen toxicity in both Taxol- and dexamethasone-pretreated cells and prevented the increase in covalent binding of acetaminophen to cellular proteins. These results demonstrate that Taxol, like dexamethasone, induces CYP3A and that increases in this P450 are responsible for increased acetaminophen toxicity.

Acute hepatotoxicity of acetaminophen in rats treated with ethanol plus isopentanol

Acetaminophen (APAP) hepatotoxicity was investigated in rats fed ethanol and isopentanol alone or in combination in a liquid diet for 7 days. Serum levels of aspartate aminotransferase (AST) and histological examination of liver slices were used to assess hepatotoxicity. At 7 hr after intragastric administration of 0.5 or 1.0 g APAP/kg, there was no significant increase in serum levels of AST in rats treated with APAP alone, or in rats pretreated with ethanol or isopentanol alone followed by APAP. There was mild central lobular congestion in the livers of rats pretreated with ethanol alone followed by APAP. In contrast, in rats pretreated with the combination of ethanol and isopentanol, administration of APAP caused a dramatic increase in serum levels of AST, along with marked central lobular necrosis, including steatosis and ischemic changes. Hepatic glutathione levels were decreased to 40-50% of control values in APAP-treated rats that had been pretreated with ethanol either alone or in combination with isopentanol. The serum concentrations of APAP were significantly lower in rats pretreated with the combination of ethanol and isopentanol followed by 1 g APAP/kg than in rats treated with APAP alone, suggesting a greater rate of APAP metabolism. We had reported previously that combined treatment of rats with ethanol and isopentanol resulted in additive to synergistic increases in CYP3A, with no further increases in CYP2E than that caused by ethanol alone. CYP3A may, therefore, be responsible for the increased APAP hepatotoxicity caused by the combined alcohol treatment.

Ethanol and isopentanol increase CYP3A and CYP2E in primary cultures of human hepatocytes

In primary cultures of human hepatocytes prepared from three separate livers, ethanol increased both CYP3A and CYP2E1, as detected immunochemically. Isopentanol, the major higher chain alcohol in alcoholic beverages, also induced CYP3A and CYP2E1. Maximal increases in these P450s occurred at the lowest concentrations of isopentanol examined, 0.1 mM. Ethanol and isopentanol were each more potent and more effective at inducing CYP3A in the human hepatocytes than was previously shown in cultured rat hepatocytes. Steady-state levels of CYP3A3/4 mRNA were increased by both ethanol and isopentanol. Ethanol and isopentanol induced immunoreactive CYP3A to a greater extent than did phenobarbital. In all three cultures, the increases in CYP3A after treatment with ethanol were less than those observed after treatment with rifampicin, a highly effective inducer of CYP3A in human hepatocytes. In one human hepatocyte culture, the lowest concentration of isopentanol tested increased CYP3A protein to an amount similar to that increased by rifampicin. In another human hepatocyte culture, however, the amount of immunoreactive CYP3A increased by isopentanol was less than that increased by rifampicin. In this latter culture, the steady-state levels of CYP3A3/4 mRNA increased by 0.1 mM isopentanol and 1 microM rifampicin were similar. This is the first finding of induction of CYP3A in human hepatocytes by ethanol or isopentanol. The clinical significance of the findings is discussed.

Synergistic increases in rat hepatic cytochrome P450s by ethanol and isopentanol

The purpose of this study was to determine if isopentanol alone or in combination with ethanol increased CYP2B1/2, CYP2E or CYP3A in the livers of rats. Increasing doses of isopentanol (0.5, 1, 2 or 3%) were administered in combination with 5.6% ethanol in the Lieber-DeCarli liquid diet for 7 days. Doses of 0.5 or 3% isopentanol were also administered alone. Isopentanol alone caused small increases in CYP2B1/2 and CYP3A. However, when isopentanol (2 or 3%) was combined with ethanol a synergistic increase in P4502B1/2 was observed. The combined alcohol treatment also resulted in a greater increase in immunoreactive CYP3A than either alcohol alone. Ethanol alone increased CYP2E 5-fold. Inclusion of isopentanol with ethanol resulted in either small or no additional increases in CYP2E. These results confirm our previous findings in cultured hepatocytes that when isopentanol is combined with ethanol, there is a synergistic increase in CYP2B1/2. Increases in CYP2B1/2, CYP2E and CYP3A protein moieties by ethanol, and by ethanol in combination with isopentanol, were associated with increases in their mRNAs. Blood isopentanol levels were 10-fold greater in rats administered 3% isopentanol in combination with ethanol compared to rats administered 3% isopentanol alone. From these results we suggest that isopentanol, a higher chain alcohol in alcoholic beverages, can contribute to increases in hepatic cytochrome P450 observed following consumption of alcoholic beverages.

Disposition of the novel anticancer agent vinorelbine ditartrate following intravenous administration in mice, rats and dogs

1. KW-2307 (vinorelbine ditartrate, CAS71486-22-1) is a new semisynthetic antitumour vinca alkaloid. Its pharmacokinetics, distribution and excretion were investigated following intravenous administration to mice (1.2 mg/kg), rats (0.12 and 1.2 mg/kg) and dogs (0.4 mg/kg). Dose levels are expressed as the free base. 2. Plasma concentrations of drug-related radioactivity declined in a bi- or tri-exponential manner, initially rapidly and then slowly (half-life of 35 h or more). Unchanged drug concentrations declined with terminal half-lives of 35.8 h in rats and 34.5h in dogs: a terminal phase was not observed in mice. KW-2307 can be characterised as a drug of high clearance (3.78, 1.73 and 1.20 l/h/kg in the mice, rats and dogs, respectively) and large volume of distribution (12.7, 41.9 and 49.6 l/kg in the mouse, rat and dog, respectively). After repeated administrations for 21 days in the rat, the accumulation ratio for unchanged drug concentrations in plasma was 1.5. 3. The extent of binding of 3H-KW-2307 in vitro to proteins in the plasma of humans, dogs, rats and mice was 89, 90, 93 and 97%, respectively. 4. In rats, concentrations of radioactivity in most tissues exceeded those in plasma, and at 0.5 h after administration were greatest in the adrenals, thyroid, pituitary, lungs, small intestine contents and kidneys. The lung is a target for drug action. Concentrations of radioactivity in the brain were lowest. In pregnant rats, placental transfer of radioactivity was low, less than 1% of the dose. Concentrations in mammary tissue, another target for drug action, exceeded those in plasma. The tissue distribution profile of radioactivity in rats was similar after single and repeated administrations. 5. Radioactivity was excreted mainly in faeces (61-73% dose in 48 h and 71-79% dose in 168 h). Biliary excretion accounted for 42.6% dose in rats during 48 h although enterohepatic cycling was probably unimportant.

Critical care experience for baccalaureate nursing students

The projected need for critical care nurses can be met through the collaborative efforts of nursing education and nursing service. An approach as implemented at our institution with the support of community agencies can be mutually beneficial. It is generally recognized that new graduates tend to seek employment where they had positive student experiences. Although few students may choose critical care as a career, the majority will have a positive memory, which is supportive of the unique contribution of critical care nursing within the scope of the health and care of patients and their families.

Critical care experience for baccalaureate nursing students

The projected need for critical care nurses can be met through the collaborative efforts of nursing education and nursing service. An approach as implemented at our institution with the support of community agencies can be mutually beneficial. It is generally recognized that new graduates tend to seek employment where they had positive student experiences. Although few students may choose critical care as a career, the majority will have a positive memory, which is supportive of the unique contribution of critical care nursing within the scope of the health and care of patients and their families.

Synergistic induction of cytochrome P450 by ethanol and isopentanol in cultures of chick embryo and rat hepatocytes

The purpose of this study was to investigate whether isopentanol, the most abundant higher chain alcohol in alcoholic beverages, contributes to induction of different forms of hepatic P450s associated with consumption of these beverages. We have previously reported that ethanol and isopentanol each induce P450 2H1/2 in cultured chick hepatocytes and that ethanol induced P450 2B1/2, as well as P450 2E, in cultured rat hepatocytes. Here we investigated the induction of P450 by isopentanol alone and in combination with ethanol in cultured chick and rat hepatocytes. The forms of induced P450 were identified both enzymatically and immunochemically. In cultured chick hepatocytes, both isopentanol and ethanol induced P450 2E, but combined treatment with these alcohols had no greater effect than treatment with ethanol alone. In cultured rat hepatocytes, isopentanol alone did not induce P450 2E or 2B1/2 and had no effect on the ethanol-mediated induction of P450 2E. However, isopentanol combined with ethanol caused a synergistic induction of P450 2B1/2 in cultured rat hepatocytes and an additive to synergistic induction of P450 2H1/2 in cultured chick hepatocytes. The levels of enzyme activities induced by the combined alcohol treatment approached those induced by potent barbiturates. The results suggest that the pentanols in alcoholic beverages may be responsible for a barbiturate-like induction of P450 in hepatocytes.

Metabolism of the anti-psoriatic agent 5-methoxypsoralen in humans: comparison with rat and dog

1. Single oral doses of 14C-5-methoxypsoralen (5-MOP) to human subjects (50 mg), rats (1 mg/kg) and dogs (1 mg/kg) were fairly well absorbed but subjected to extensive first-pass metabolism, at least in rat and human. Means of 62, 51 and 40% dose in urine and 31, 38 and 48% dose in faeces, were excreted by humans (during 5 days), rats (3 days) and dogs (1 day), respectively. In dogs, faecal 14C was probably derived, in part, from biliary excreted material. 2. Total 14C in human plasma reached peak concentrations after 2 h (mean 235 ng 5-MOP equivalent/ml) and declined relatively slowly, to about 60% of this value within 24 h. Unchanged 5-MOP was not detected in plasma using h.p.l.c. (< 5 ng/ml). 3. Tissue concentrations of 14C were generally greater in dogs than rats and reached peak levels at 1 h in dogs but at 24 h in rats. Apart from liver and bile, dog tissue 14C concentrations were lower than those in the corresponding plasma, whereas in rat they were lower only until the time of peak concentrations, after which they were generally greater. 4. 5-MOP was extensively metabolized in all three species. The major 14C-components in human and dog urine were glucuronic acid conjugates, mainly of an arylacetic acid and arylalcohols, resulting from initial oxidative metabolism of the furan ring of 5-MOP. In rat, these metabolites were excreted mainly unconjugated. An unusual metabolite was formed by reduction of the lactone moiety of 5-MOP, probably by the gut flora, giving rise to an arylpropionic acid, excreted as a glucuronic acid conjugate in the urine of all three species. 5. Unchanged drug was a very minor component of human and rat plasma, but a major component of dog plasma. In all three species, circulating 14C-metabolites were similar to those in the urine but were present mainly unconjugated. On the basis of these data, the metabolic fate of 5-MOP in humans was more similar to that in dog than to that in rat, although humans appeared to metabolize 5-MOP more rapidly than did dog.

2-Amino-3,4-dimethylimidazo[4,5-f]quinoline induces and inhibits cytochrome P450 from the IA subfamily in chick and rat hepatocytes

Several heterocyclic amines, found in cooked food, are powerful mutagens in the Ames Salmonella mutagenicity test system. One of these, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) is one of the most mutagenic chemicals tested in this assay. In primary cultures of chick and rat hepatocytes, MeIQ, by itself, induced cytochrome P450 from the IA subfamily but was a weak inducer compared to 3-methylcholanthrene. However, in both chick and rat hepatocytes in culture, MeIQ decreased the amount of 3-methylcholanthrene-induced ethoxyresorufin deethylase activity, which is catalyzed by cytochrome P450 IA. The protein moiety of cytochrome P450 IA was decreased at MeIQ concentrations of 2.5 micrograms/ml or greater in chick hepatocytes and 25 micrograms/ml in rat hepatocytes. In hepatic microsomes from methylcholanthrene-treated chicks and rats, MeIQ was a competitive inhibitor of both ethoxyresorufin deethylase activity, a reaction catalyzed mainly by rodent cytochrome P450 IA1, and uroporphyrinogen oxidation, a reaction catalyzed by rodent P450 IA2. In cultured chick hepatocytes, MeIQ also decreased cytochrome P450-mediated oxidation of uroporphyrinogen by intact cells. The ability of MeIQ to inhibit as well as to induce cytochrome P450s of the IA subfamily may be important in assessing the mutagenic and carcinogenic effects of MeIQ in mammals.

Evaluation of the antiviral activity of anthraquinones, anthrones and anthraquinone derivatives against human cytomegalovirus

A number of anthraquinones, anthrones and anthraquinone derivatives were evaluated for antiviral activity against human cytomegalovirus (HCMV) as well as for cytotoxicity. Of those compounds evaluated, quinalizarin, emodin, rhein, hypericin, protohypericin, alizarin, emodin bianthrone and emodin anthrone showed antiviral activity against a normal laboratory HCMV strain, AD-169. When tested against a ganciclovir-resistant strain of HCMV, the EC50 values for quinalizarin, rhein and alizarin were superior to the values obtained for the AD-169 strain of HCMV. These results suggest that these compounds will be useful as prototypes for synthesizing a class of anti-HCMV drugs that are effective against ganciclovir-sensitive and -resistant strains of HCMV.

Studies of the pharmacokinetics and metabolism of 4-amino-propiophenone (PAPP) in rats, dogs and cynomolgus monkeys

The pharmacokinetics and metabolism of 4-aminopropiophenone (PAPP), a cyanide antidote, have been studied in rats, dogs and cynomolgus monkeys using 14C-PAPP. Radiolabelled material was rapidly excreted in all three species, mainly in urine. In rats, PAPP was metabolized by N-acetylation, while in dogs, ring and aliphatic hydroxylation occurred. In monkeys, both N-acetylation and oxidation took place. In the latter pathway, PAPP was oxidized to p-aminobenzoic acid which underwent amino acid-conjugation to p-aminohippuric acid. In rat blood in vitro, the PAPP metabolites, p-aminobenzoic, p-aminohippuric and N-acetyl-p-aminobenzoic acid were only weak methaemoglobin producers.

In vitro virucidal activity of selected anthraquinones and anthraquinone derivatives

Anthraquinones and anthraquinone derivatives were characterized for their antiviral and virucidal activities against viruses representing several taxonomic groups. One of these compounds, hypericin, had activity against vesicular stomatitis virus, herpes simplex virus types 1 and 2, parainfluenza virus, and vaccinia virus (from 0.5 to 3.8 log10 reductions in infectivity) at concentrations of less than 1 microgram/ml as determined by a direct pre-infection incubation assay. Human rhinovirus was not sensitive to hypericin at concentrations up to 10 micrograms/ml. Addition of small amounts of Tween-80 to solutions containing hypericin enhanced, by up to 2.6 log10, hypericin's virucidal activity. Anthraquinones and anthraquinone derivatives with the hydroxyl and alkyl substitution pattern of emodin (i.e. emodin, emodin anthrone, emodin bianthrone and hypericin) were active against the enveloped viruses tested. The following general pattern of activity was found: hypericin greater than emodin bianthrone greater than emodin anthrone greater than emodin. Chrysophanic acid, aloe-emodin, and sennosides A and B did not possess activity against any of the viruses tested.

Nucleic acid related compounds. 65. New syntheses of 1-(beta-D-arabinofuranosyl)-5(E)-(2-iodovinyl)uracil (IVAraU) from vinylsilane precursors. Radioiodine uptake as a marker for thymidine kinase positive herpes viral infections

(Trimethylsilyl)acetylene was coupled with 1-(2,3,5-tri-O-acetyl-beta-D- arabinofuranosyl)-5-iodouracil to give 1- (2,3,5-tri-O-acetyl-beta-D-arabinofuranosyl)-5-[2-(trimethylsilyl)eth yny l] uracil. Lindlar hydrogenation of 4 gave 1-(2,3,4-tri-O-acetyl-beta-D-arabinofuranosyl)-5(Z)-[2- (trimethylsilyl)vinyl]uracil. Treatment of 5 with iodine monochloride (or sodium iodide/phenyliodine(III) dichloride) in benzene gave 1-(2,3,5-tri-O-acetyl-beta-D-arabinofuranosyl)-5(E)-(2-iodovinyl)uracil (7), whereas polar solvents favored the (Z)-iodovinyl isomer 8. Deacetylation of 7 gave 1-(beta-D-arabinofuranosyl)-5(E)-(2-iodovinyl)uracil (IVAraU, 9). A microscale in situ synthesis with Na*I gave [*I]IVAraU. Treatment of HSV-infected cells with [125I]IVAraU resulted in virus-dependent uptake associated with nucleoside phosphorylation by wild type or acyclovir-resistant DNA polymerase mutants (but not with TK-HSV-1 mutants). Uptake was virus-inoculum dependent and was detectable within 4 h postinfection. The process was not completely reversible. Virus-specified uptake of [125I]IVAraU may allow automated in vitro detection of HSV isolates.

Critical care concepts in baccalaureate nursing education

The high response rate of 65.1 percent to this survey suggests nurse educators across the country are interested and involved with the incorporation of critical care concepts in baccalaureate nursing education. Nurse educators are conscientiously working to provide an educational basis for graduate nurses to adequately address the complex healthcare needs of our society. Cooperative efforts between nurse educators and practicing critical care nurses can make a difference in the future delivery of healthcare.

HPLC analysis of allicin and other thiosulfinates in garlic clove homogenates

Reversed-phase high Performance liquid chromatography (C18-HPLC) was used to separate and quantitate all the detectable alkyl and alkenyl thiosulfinates, including configurational isomers, of garlic homogenates. Pure thiosulfinates were synthesized or isolated and identified by (1)H-NMR, and their extinction coefficients determined. Some configurational isomers required Separation by silica-HPLC. Five previously unreported thiosulfinates have been found, four of which contain the TRANS-1-propenyl group and increase several-fold to over half the content of allicin upon storage of garlic bulbs at 4 degrees C with a concomitant decrease in a gamma-glutamyl peptide. The variation in thiosulfinate yield between different countries, stores, bulbs, cloves, and storage times was investigated. A method for standardizing the quantitation of allicin yield from garlic is proposed and compared to other methods of allicin analysis.

Critical care concepts in baccalaureate nursing education

The high response rate of 65.1 percent to this survey suggests nurse educators across the country are interested and involved with the incorporation of critical care concepts in baccalaureate nursing education. Nurse educators are conscientiously working to provide an educational basis for graduate nurses to adequately address the complex healthcare needs of our society. Cooperative efforts between nurse educators and practicing critical care nurses can make a difference in the future delivery of healthcare.

The formation of methaemoglobin by 4-aminopropiophenone (PAPP) and 4-(N-hydroxy) aminopropiophenone

Oral dosing of rats with the cyanide antidote 4-aminopropiophenone (PAPP), brought about peak methaemoglobin levels at 15-40 min, but peak levels were attained at at 15-25 min after intravenous dosing. After both oral and intravenous administration at equimolar doses, 4-(N-hydroxy)aminopropiophenone (PHAPP), the putative methaemoglobin-producing metabolite of PAPP, produced higher peak levels of methaemoglobin than PAPP. Plasma from rats injected with PAPP was capable of forming methaemoglobin when added to naive rat erythrocytes. The identity of the metabolite responsible is discussed.

Synthetic peptide substrates for the immunoglobulin A1 protease from Neisseria gonorrhoeae (type 2)

Neisseria gonorrhoeae secretes protease which inactive human immunoglobulin A1 (IgA1) by cleavage of specific peptide bonds in the hinge region. The type 2 IgA1 protease (EC 3.4.24.13) is secreted as a 169-kDa precursor which undergoes autoproteolysis at three sites (A, B, and C) to release the 106-kDa active form of the enzyme (J. Pohlner, R. Halter, K. Beyreuther, and T. F. Meyer. Nature [London] 325:458-462, 1987). Synthetic decapeptides consisting of five residues on each side of the three autoproteolytic cleavage sites and their potential pentapeptide catabolites were prepared by solid-phase synthesis. Cleavage of the decapeptides by the type 2 IgA1 protease from N. gonorrhoeae was monitored by high-performance liquid chromatography. Peptides homologous with the amino acid sequences around the B and C sites are cleaved by the IgA1 protease. Amino acid analysis and Edman degradation show that the cleavage products have both the composition and amino acid sequence which would be expected from cleavage at the predicted sites. Km values of 1.35 mM and 3.43 mM and kcat values of 280 pmol/h/U and 439 pmol/h/U for the site B and site C peptides, respectively, were determined. The catalytic efficiency (kcat/Km) for the synthetic substrates is about 10% of that reported for intact IgA1. Cleavage of the peptides is inhibited by IgA1 protease inhibitors such as the tetrapeptide substrate analog inhibitor HRP-48, human colostrum, and a peptide-boronate transition state inhibitor. An extract from an N. gonorrhoeae construct lacking active IgA1 protease failed to cleave the synthetic substrate, while an extract from the control construct which secretes active enzyme completely hydrolyzed the synthetic peptide. Neither the site A peptide nor synthetic decapeptides encompassing cleavage sites in the hinge region of IgA1 are hydrolyzed by IgA1 protease. These are the first synthetic substrates to be reported for any IgA1 protease.

Hemolysis of erythrocytes and fluorescence polarization changes elicited by peptide toxins, aliphatic alcohols, related glycols and benzylidene derivatives

Hemolysis rates of human erythrocytes induced by C2 and C8-C14 straight chain 1-alkanols, 1,2-alkanediols and the corresponding benzylidene derivatives (benzaldehyde acetals) have been studied and compared with hemolysis rates obtained by three peptide toxins. The peak of activity occurs at C12 for the alkanols and glycols and at C10 for the benzylidene derivatives. The most active compound is 1-dodecanol, followed by 1,2-dodecanediol and the C10 benzylidene acetal, which show 50% hemolysis at 15, 99 and 151 microM, respectively, at 37 degrees C. A few lysolecithins and longer chain cis-unsaturated alcohols were studied for comparison purposes, and were found to be more active than 1-dodecanol. The most active were the 16:0 lysolecithin and cis-9-tetradecene-1-ol, which gave 50% hemolysis at concentrations of 2.8 and 5.6 microM respectively. The hemolytic activities of 1-dodecanol, 1,2-dodecanediol and the C10 benzylidene acetal were compared to activities of Pyrularia thionin and melittin with cow, horse, sheep, pig and human erythrocytes. Whereas the peptide toxins showed clear specificity for human erythrocytes, no selectivity was shown by any of the other compounds tested. Addition of the thionin or Naja naja kaouthia cardiotoxin to erythrocyte ghosts caused a slight but reproducible increase in the order of the phospholipid bilayer, as measured with the fluorescent probe NBD-PC. Cardiotoxin gave a greater response than did the P thionin, and extensively iodinated P thionin gave a smaller change than did P thionin. Similar results were obtained with melittin, but this peptide gave a markedly greater response than all other peptides. Addition of dodecanol or the C10 benzylidene acetal caused a marked increase in membrane fluidity. All of these data indicate that the organic compounds interact directly with and are incorporated nonspecifically into the membrane lipid bilayer, but the peptide toxins interact specifically with some component on the surface of the membrane, either a protein or specific phospholipid domain, followed by insertion into the membrane and decreasing phospholipid movement.

Tetrapeptide inhibitors of the IgA1 proteinases from type I Neisseria gonorrhoeae

The six series of unique tetrapeptides and their blocked N-acetyl, C-amide, and N-acetyl-C-amide analogues which comprise the hinge region of human IgA1 (Ser224 to Ser240) have been synthesized and tested as inhibitors of the type 1 IgA1 proteinase elaborated by Neisseria gonorrhoeae (EC 3.4.24.13). Most series had at least one member with an IC50 value less than 1 mM. The most effective inhibitors came from the series Ser-Thr-Pro-Pro (P4-P1) and Pro-Thr-Pro-Ser (P1-P3'). One member from each series had an IC50 value in the low microM range. Magnetic resonance studies (Siemion, I. Z.; et al. Biophys. Chem. 1988, 31, 35) indicate that the various tetrapeptide series appear to have different preferred solution conformations. However, these do not appear to be correlated with affinity for the neisserial proteinase. The most effective inhibitors tend to have a threonine residue adjacent to the N-terminus and the P1 or P1' residues at either the N- or the C-terminus. These relationships are not exclusive however, as other inhibitors, which do not meet these criteria, bind reasonably well. The most effective substrate analogues outlined here are about one-half the size and bind to the neisserial proteinase 2 orders of magnitude more tightly than previously reported inhibitors.