Paradoxical Patterns of Sinusoidal Obstruction Syndrome-Like Liver Injury in Aged Female CD-1 Mice Triggered by Cannabidiol-Rich Cannabis Extract and Acetaminophen Co-Administration.

The goal of this study was to investigate the potential for a cannabidiol-rich cannabis extract (CRCE) to interact with the most common over-the-counter drug and the major known cause of drug-induced liver injury-acetaminophen (APAP)-in aged female CD-1 mice. Gavaging mice with 116 mg/kg of cannabidiol (CBD) [mouse equivalent dose (MED) of 10 mg/kg of CBD] in CRCE delivered with sesame oil for three consecutive days followed by intraperitoneally (i.p.) acetaminophen (APAP) administration (400 mg/kg) on day 4 resulted in overt toxicity with 37.5% mortality. No mortality was observed in mice treated with 290 mg/kg of CBD+APAP (MED of 25 mg/kg of CBD) or APAP alone. Following CRCE/APAP co-administration, microscopic examination revealed a sinusoidal obstruction syndrome-like liver injury-the severity of which correlated with the degree of alterations in physiological and clinical biochemistry end points. Mechanistically, glutathione depletion and oxidative stress were observed between the APAP-only and co-administration groups, but co-administration resulted in much greater activation of c-Jun N-terminal kinase (JNK). Strikingly, these effects were not observed in mice gavaged with 290 mg/kg CBD in CRCE followed by APAP administration. These findings highlight the potential for CBD/drug interactions, and reveal an interesting paradoxical effect of CBD/APAP-induced hepatotoxicity.

Impact of obesity on the toxicity of a multi-ingredient dietary supplement, OxyELITE Pro™ (New Formula), using the novel NZO/HILtJ obese mouse model: Physiological and mechanistic assessments.

Herbal dietary supplement (HDS)-induced hepato- and cardiotoxicity is an emerging clinical problem. In this study, we investigated the liver and heart toxicity of HDS OxyELITE-PRO™ New Formula (OEP-NF), a dietary supplement marketed for weight loss and performance enhancement that was recently withdrawn from the market. Using a novel NZO/HlLtJ obese mouse model, we demonstrated that administration of clinically relevant mouse equivalent doses (MED) of OEP-NF produced cardio- and hepatotoxic risks following both short- and long-term administration schedules. Specifically, gavaging female NZO/HlLtJ with up to 2X MED of OEP-NF resulted in 40% mortality within two weeks. Feeding mice with either 1X or 3X MED of OEP-NF for eight weeks, while not exhibiting significant effects on body weights, significantly altered hepatic gene expression, increased the number of apoptotic and mast cells in the heart and affected cardiac function. The degree of toxicity in NZO/HlLtJ mice was higher than that observed previously in non-obese CD-1 and B6C3F1 strains, suggesting that an overweight/obese condition can sensitize mice to OEP-NF. Adverse health effects linked to OEP-NF, together with a number of other hepato- and cardiotoxicity cases associated with HDS ingestion, argue strongly for introduction of quality standards and pre-marketing safety assessments for multi-ingredient HDS.

Safety assessment of the dietary supplement OxyELITE™ Pro (New Formula) in inbred and outbred mouse strains.

Herbal dietary supplements have gained wide acceptance as alternatives to conventional therapeutic agents despite concerns regarding their efficacy and safety. In 2013, a spate of severe liver injuries across the United States was linked to the dietary supplement OxyELITE Pro-New Formula (OEP-NF), a multi-ingredient product marketed for weight loss and exercise performance enhancement. The principal goal of this study was to assess the hepatotoxic potential of OEP-NF in outbred and inbred mouse models. In an acute toxicity study, significant mortality was observed after administering 10X and 3X mouse-equivalent doses (MED) of OEP-NF, respectively. Increases in liver/body weight ratio, ALT and AST were observed in female B6C3F1 mice after gavaging 2X and 1.5X MED of OEP-NF. Similar findings were observed in a 90-day feeding study. These alterations were paralleled by altered expression of gene- and microRNA-signatures of hepatotoxicity, including Cd36, Nqo1, Aldoa, Txnrd1, Scd1 and Ccng1, as well as miR-192, miR-193a and miR-125b and were most pronounced in female B6C3F1 mice. Body weight loss, observed at week 1, was followed by weight gain throughout the feeding studies. These findings bolster safety and efficacy concerns for OEP-NF, and argue strongly for implementation of pre-market toxicity studies within the dietary supplement industry.

The effects of massage therapy to induce sleep in infants born preterm.

PURPOSE: The aim of this study was to determine whether massage therapy can be used as an adjunct intervention to induce sleep in infants born preterm. METHODS: Thirty infants born at a minimum of 28 weeks gestational age, who were at the time of the study between 32 and 48 weeks adjusted gestational age, were randomly assigned to receive massage therapy on 1 day and not receive massage on an alternate day. The Motionlogger Micro Sleep Watch Actigraph recorded lower extremity activity on the morning of each day. RESULTS: No significant difference was found between groups for sleep efficiency (P = .13) during the time period evaluated. Groups differed significantly during the time period after the massage ended with more infants sleeping on the nonmassage day (χ = 4.9802, P = .026). CONCLUSIONS: Massage is well tolerated in infants born preterm and infants do not fall asleep faster after massage than without massage.

Long-term deficits of preterm birth: evidence for arousal and attentional disturbances.

OBJECTIVE: Quantitative measures of pre-attentional, attentional and frontal lobe processes were compared to evaluate quantitative measures of these deficits in Ex-Preterm vs. Ex-Term adolescents. METHODS: We compared 43 Ex-Preterm with 26 Ex-Term adolescents using the P50 auditory potential, the Psychomotor Vigilance Task (PVT), a reaction time (RT) test, and Near Infrared Spectroscopy (NIRS). RESULTS: The mean amplitude (+/-SE) of the P50 amplitude was similar in the Ex-Preterm (1.8+/-1.4 microV) vs. Ex-Term adolescents (1.8+/-0.6 microV, df = 68, F = 0.05, p = 0.8), but the Ex-Preterm group showed a trimodal distribution in amplitude (High, 3.3+/-0.4 microV, df=42.25, F=19.2, p < 0.01; Medium, 1.7+/-0.1 microV, df = 39, F = 0.41, p = 0.53; Low, 0.7+/-0.1 microV, df = 40, F = 49.5, p < 0.01) suggested by statistically significant variance between populations (Kolmogorov-Kuiper test, df = 42.25, F = 5.4, p < 0.01). Mean RT was longer in Ex-Preterm (250+/-8 ms) vs. Ex-Term subjects (200+/-5 ms, df = 68, F = 18.8, p < 0.001). PVT lapses were increased in Ex-Preterm subjects, and varied inversely with P50 amplitude (Overall Mean 17+/-5 lapses, df = 67, F = 5.34, p < 0.05; Low P50 amplitude, 25+/-10, df = 40, F = 8.8, p < 0.01; Medium, 21+/-11, df = 38, F = 5.37, p < 0.05; High, 6+/-2, df = 39, F = 6.78, p < 0.01) vs. Ex-Term subjects (2+/-0.4 lapses, p < 0.01). NIRS levels did not differ statistically, but tended to correlate with P50 amplitude in the Ex-Preterm group. CONCLUSIONS: These findings suggest differential pre-attentional, attentional and frontal lobe dysfunction in Ex-Preterm adolescents. SIGNIFICANCE: These measures could provide a means to objectively assess differential dysregulation of arousal and attention in Ex-Preterm adolescents, allowing optimization of therapeutic designs.

Clinical assessment of CYP2D6-mediated herb-drug interactions in humans: effects of milk thistle, black cohosh, goldenseal, kava kava, St. John's wort, and Echinacea.

Cytochrome P450 2D6 (CYP2D6), an important CYP isoform with regard to drug-drug interactions, accounts for the metabolism of approximately 30% of all medications. To date, few studies have assessed the effects of botanical supplementation on human CYP2D6 activity in vivo. Six botanical extracts were evaluated in three separate studies (two extracts per study), each incorporating 16 healthy volunteers (eight females). Subjects were randomized to receive a standardized botanical extract for 14 days on separate occasions. A 30-day washout period was interposed between each supplementation phase. In study 1, subjects received milk thistle (Silybum marianum) and black cohosh (Cimicifuga racemosa). In study 2, kava kava (Piper methysticum) and goldenseal (Hydrastis canadensis) extracts were administered, and in study 3 subjects received St. John's wort (Hypericum perforatum) and Echinacea (Echinacea purpurea). The CYP2D6 substrate, debrisoquine (5 mg), was administered before and at the end of supplementation. Pre- and post-supplementation phenotypic trait measurements were determined for CYP2D6 using 8-h debrisoquine urinary recovery ratios (DURR). Comparisons of pre- and post-supplementation DURR revealed significant inhibition (approximately 50%) of CYP2D6 activity for goldenseal, but not for the other extracts. Accordingly, adverse herb-drug interactions may result with concomitant ingestion of goldenseal supplements and drugs that are CYP2D6 substrates.

Gauging the clinical significance of P-glycoprotein-mediated herb-drug interactions: comparative effects of St. John's wort, Echinacea, clarithromycin, and rifampin on digoxin pharmacokinetics.

Concomitant administration of botanical supplements with drugs that are P-glycoprotein (P-gp) substrates may produce clinically significant herb-drug interactions. This study evaluated the effects of St. John's wort and Echinacea on the pharmacokinetics of digoxin, a recognized P-gp substrate. Eighteen healthy volunteers were randomly assigned to receive a standardized St. John's wort (300 mg three times daily) or Echinacea (267 mg three times daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (300 mg twice daily, 7 days) and clarithromycin (500 mg twice daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxin 0.25 mg) was administered orally before and after each supplementation and control period. Serial digoxin plasma concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the curve (AUC)((0-3)), AUC((0-24)), elimination half-life, and maximum serum concentration were used to assess the effects of St. John's wort, Echinacea, rifampin, and clarithromycin on digoxin disposition. St. John's wort and rifampin both produced significant reductions (p < 0.05) in AUC((0-3)), AUC((0-24)), and C(max), while clarithromycin increased these parameters significantly (p < 0.05). Echinacea supplementation did not affect digoxin pharmacokinetics. Clinically significant P-gp-mediated herb-drug interactions are more likely to occur with St. John's wort than with Echinacea.

Effect of goldenseal (Hydrastis canadensis) and kava kava (Piper methysticum) supplementation on digoxin pharmacokinetics in humans.

Phytochemical-mediated modulation of P-glycoprotein (P-gp) and other drug transporters may give rise to many herb-drug interactions. Serial plasma concentration-time profiles of the P-gp substrate, digoxin, were used to determine whether supplementation with goldenseal or kava kava modified P-gp activity in vivo. Twenty healthy volunteers were randomly assigned to receive a standardized goldenseal (3210 mg daily) or kava kava (1227 mg daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (600 mg daily, 7 days) and clarithromycin (1000 mg daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxin, 0.5 mg) was administered p.o. before and at the end of each supplementation and control period. Serial digoxin plasma concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the curve (AUC)((0-3)), AUC((0-24)), C(max,) CL/F, and elimination half-life were used to assess the effects of goldenseal, kava kava, rifampin, and clarithromycin on digoxin pharmacokinetics. Rifampin produced significant reductions (p < 0.01) in AUC((0-3)), AUC((0-24)), CL/F, t(1/2), and C(max), whereas clarithromycin increased these parameters significantly (p < 0.01). With the exception of goldenseal's effect on C(max) (14% increase), no statistically significant effects on digoxin pharmacokinetics were observed following supplementation with either goldenseal or kava kava. When compared with rifampin and clarithromycin, supplementation with these specific formulations of goldenseal or kava kava did not appear to affect digoxin pharmacokinetics, suggesting that these supplements are not potent modulators of P-gp in vivo.

Test-retest reliability of in situ unaided thresholds in adults.

PURPOSE: The purpose of this study was to examine test-retest reliability of in situ unaided thresholds measured using a handheld hearing aid programmer coupled to a hearing aid transducer in adults with normal hearing. METHOD: Randomized in situ thresholds at 4 octave frequencies were established in 1 ear of 43 adults twice using the Widex Diva SP3 device with the stimulus generated by and transduced through a Widex Diva SD-9 behind-the-ear hearing aid. Insert earphone tips were used in each of the measures to couple the hearing aid/transducer to the ear canal. RESULTS: Mean decibel differences between the test and retest thresholds were less than 1 dB at each frequency. Using an 80% statistical test criterion, results revealed test-retest reliability within 5 dB for all frequencies: 98% at 500 Hz, 100% at 1000 and 2000 Hz, and 93% at 4000 Hz. CONCLUSIONS: Test-retest reliability of in situ unaided thresholds using the SP3/SD-9 device is equivalent to that of currently accepted audiometric procedures.

Assessing the clinical significance of botanical supplementation on human cytochrome P450 3A activity: comparison of a milk thistle and black cohosh product to rifampin and clarithromycin.

Phytochemical-mediated modulation of cytochrome P450 enzymes (CYPs) may underlie many herb-drug interactions. This study's purpose was to assess the effects of milk thistle and black cohosh supplementation on CYP3A activity and compare them to a clinically recognized inducer, rifampin, and inhibitor, clarithromycin. Healthy volunteers were randomly assigned to receive a standardized milk thistle (900 mg) or black cohosh (80 mg) supplement for 14 days. Subjects also received rifampin (600 mg) and clarithromycin (1000 mg) for 7 days as positive controls for CYP3A induction and inhibition, respectively. Midazolam was administered orally before and after each supplementation and control period. The effects of milk thistle, black cohosh, rifampin, and clarithromycin on midazolam pharmacokinetics were determined using noncompartmental techniques. Unlike those observed for rifampin and clarithromycin, midazolam pharmacokinetics was unaffected by milk thistle or black cohosh. Milk thistle and black cohosh appear to have no clinically relevant effect on CYP3A activity in vivo.

Effect of milk thistle (Silybum marianum) and black cohosh (Cimicifuga racemosa) supplementation on digoxin pharmacokinetics in humans.

Phytochemical-mediated modulation of P-glycoprotein (P-gp) and other drug transporters may underlie many herb-drug interactions. Serial serum concentration-time profiles of the P-gp substrate, digoxin, were used to determine whether supplementation with milk thistle or black cohosh modified P-gp activity in vivo. Sixteen healthy volunteers were randomly assigned to receive a standardized milk thistle (900 mg daily) or black cohosh (40 mg daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (600 mg daily, 7 days) and clarithromycin (1000 mg daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxicaps, 0.4 mg) was administered orally before and at the end of each supplementation and control period. Serial digoxin serum concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the serum concentration time curves from 0 to 3 h (AUC(0-3)), AUC(0-24), Cmax, apparent oral clearance of digoxin (CL/F), and elimination half-life were used to assess the effects of milk thistle, black cohosh, rifampin, and clarithromycin on digoxin pharmacokinetics. Rifampin produced significant reductions (p < 0.01) in AUC(0-3), AUC(0-24), and Cmax, whereas clarithromycin increased these parameters significantly (p < 0.01). Significant changes in digoxin half-life and CL/F were also observed with clarithromycin. No statistically significant effects on digoxin pharmacokinetics were observed following supplementation with either milk thistle or black cohosh, although digoxin AUC(0-3) and AUC(0-24) approached significance (p = 0.06) following milk thistle administration. When compared with rifampin and clarithromycin, supplementation with these specific formulations of milk thistle or black cohosh did not appear to affect digoxin pharmacokinetics, suggesting that these supplements are not potent modulators of P-gp in vivo.

Clinical assessment of effects of botanical supplementation on cytochrome P450 phenotypes in the elderly: St John's wort, garlic oil, Panax ginseng and Ginkgo biloba.

OBJECTIVES: Elderly patients are more likely to ingest prescription medications concurrently with botanical supplements, and may therefore be vulnerable to herb-drug interactions. Phytochemical-mediated modulation of cytochrome P450 (CYP) activity may underlie many herb-drug interactions. Some evidence suggests that CYP activity may decrease in the elderly. If so, herb-mediated changes in CYP activity may take on greater clinical relevance in this population. In this study, single timepoint, phenotypic metabolic ratios were used to determine whether long-term supplementation of St John's wort, garlic oil, Panax ginseng, and Ginkgo biloba affected CYP1A2, CYP2D6, CYP2E1 or CYP3A4 activity in elderly subjects. METHODS: Twelve healthy volunteers between the ages of 60 and 76 years (mean age 67 years) were randomly assigned to receive each botanical supplement for 28 days followed by a 30-day washout period. Probe drug cocktails of midazolam, caffeine, chlorzoxazone and debrisoquine were administered before and at the end of supplementation. Pre- and post-supplementation phenotypic ratios were determined for CYP3A4, CYP1A2, CYP2E1 and CYP2D6 using 1-hydroxymidazolam/midazolam serum ratios (1-hour), paraxanthine/caffeine serum ratios (6-hour), 6-hydroxychlorzoxazone/chlorzoxazone serum ratios (2-hour) and debrisoquine urinary recovery ratios (8-hour), respectively. The content of purported 'active' phytochemicals was determined for each supplement. RESULTS: Comparisons of pre- and post-St John's wort phenotypic ratios revealed significant induction of CYP3A4 (approximately 140%) and CYP2E1 activity (approximately 28%). Garlic oil inhibited CYP2E1 activity by approximately 22%. P. ginseng inhibition of CYP2D6 was statistically significant, but the magnitude of the effect (approximately 7%) did not appear to be clinically relevant. None of the supplements tested in this study appeared to affect CYP1A2 activity. CONCLUSIONS: Elderly subjects, like their younger counterparts, are susceptible to herb-mediated changes in CYP activity, especially those involving St John's wort. Pharmacokinetic herb-drug interactions stemming from alterations in CYP activity may adversely affect drug efficacy and/or toxicity. When compared with earlier studies that employed young subjects, the data suggest that some age-related changes in CYP responsivity to botanical supplementation may exist. Concomitant ingestion of botanical supplements with prescription medications, therefore, should be strongly discouraged in the elderly.

In vivo effects of goldenseal, kava kava, black cohosh, and valerian on human cytochrome P450 1A2, 2D6, 2E1, and 3A4/5 phenotypes.

OBJECTIVES: Phytochemical-mediated modulation of cytochrome P450 (CYP) activity may underlie many herb-drug interactions. Single-time point phenotypic metabolic ratios were used to determine whether long-term supplementation of goldenseal ( Hydrastis canadensis ), black cohosh ( Cimicifuga racemosa ), kava kava ( Piper methysticum ), or valerian ( Valeriana officinalis ) extracts affected CYP1A2, CYP2D6, CYP2E1, or CYP3A4/5 activity. METHODS: Twelve healthy volunteers (6 women) were randomly assigned to receive goldenseal, black cohosh, kava kava, or valerian for 28 days. For each subject, a 30-day washout period was interposed between each supplementation phase. Probe drug cocktails of midazolam and caffeine, followed 24 hours later by chlorzoxazone and debrisoquin (INN, debrisoquine), were administered before (baseline) and at the end of supplementation. Presupplementation and postsupplementation phenotypic trait measurements were determined for CYP3A4/5, CYP1A2, CYP2E1, and CYP2D6 by use of 1-hydroxymidazolam/midazolam serum ratios (1-hour sample), paraxanthine/caffeine serum ratios (6-hour sample), 6-hydroxychlorzoxazone/chlorzoxazone serum ratios (2-hour sample), and debrisoquin urinary recovery ratios (8-hour collection), respectively. The content of purported "active" phytochemicals was determined for each supplement. RESULTS: Comparisons of presupplementation and postsupplementation phenotypic ratio means revealed significant inhibition (approximately 40%) of CYP2D6 (difference, -0.228; 95% confidence interval [CI], -0.268 to -0.188) and CYP3A4/5 (difference, -1.501; 95% CI, -1.840 to -1.163) activity for goldenseal. Kava produced significant reductions (approximately 40%) in CYP2E1 only (difference, -0.192; 95% CI, -0.325 to -0.060). Black cohosh also exhibited statistically significant inhibition of CYP2D6 (difference, -0.046; 95% CI, -0.085 to -0.007), but the magnitude of the effect (approximately 7%) did not appear to be clinically relevant. No significant changes in phenotypic ratios were observed for valerian. CONCLUSIONS: Botanical supplements containing goldenseal strongly inhibited CYP2D6 and CYP3A4/5 activity in vivo, whereas kava inhibited CYP2E1 and black cohosh weakly inhibited CYP2D6. Accordingly, serious adverse interactions may result from the concomitant ingestion of goldenseal supplements and drugs that are CYP2D6 and CYP3A4/5 substrates. Kava kava and black cohosh may interact with CYP2E1 and CYP2D6 substrates, respectively. Valerian appears to be less likely to produce CYP-mediated herb-drug interactions.

In vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, and saw palmetto.

OBJECTIVES: Phytochemical-mediated modulation of cytochrome P450 (CYP) activity may underlie many herb-drug interactions. Single-time point phenotypic metabolic ratios were used to determine whether long-term supplementation of Citrus aurantium , Echinacea purpurea , milk thistle (Silybum marianum), or saw palmetto (Serenoa repens) extracts affected CYP1A2, CYP2D6, CYP2E1, or CYP3A4 activity. METHODS: Twelve healthy volunteers (6 women, 6 men) were randomly assigned to receive C aurantium , E purpurea , milk thistle, or saw palmetto for 28 days. For each subject, a 30-day washout period was interposed between each supplementation phase. Probe drug cocktails of midazolam and caffeine, followed 24 hours later by chlorzoxazone and debrisoquin (INN, debrisoquine), were administered before (baseline) and at the end of supplementation. Presupplementation and postsupplementation phenotypic trait measurements were determined for CYP3A4, CYP1A2, CYP2E1, and CYP2D6 by use of 1-hydroxymidazolam/midazolam serum ratios (1-hour sample), paraxanthine/caffeine serum ratios (6-hour sample), 6-hydroxychlorzoxazone/chlorzoxazone serum ratios (2-hour sample), and debrisoquin urinary recovery ratios (8-hour collection), respectively. The content of purported "active" phytochemicals was determined for each supplement. RESULTS: Comparisons of presupplementation and postsupplementation phenotypic ratios suggested that these particular supplements had no significant effect on CYP1A2, CYP2D6, CYP2E1, or CYP3A4 activity. Phytochemical profiles indicated that C aurantium was devoid of the CYP3A4 inhibitor 6',7'-dihydroxybergamottin. Quantities of fatty acids, flavonolignans, and cichoric acid were consistent with label claims for saw palmetto, milk thistle, and E purpurea , respectively. CONCLUSIONS: Botanical supplements containing C aurantium , milk thistle, or saw palmetto extracts appear to pose a minimal risk for CYP-mediated herb-drug interactions in humans. Although the effects of E purpurea on CYP activity were minor, further study into the interaction potential of this botanical is merited.

Intimal hyperplasia following carotid endarterectomy in an insulin-resistant rat model.

Hyperhomocysteinemia, a known risk factor for cardiovascular disease, results in an elevation of intimal hyperplasia (IH) following a carotid endarterectomy (CEA) in a rat model. An exaggerated IH response following CEA has been observed in rats with dietary induced hyperhomocysteinemia. Type 2 diabetics often present with hyperhomocysteinemia and are at higher risk for developing vascular blockage following surgical procedures. To determine if insulin resistance increases IH risks following endarterectomy, the 3 goals of this study were: (1) to establish plasma homocysteine concentrations in dietary induced insulin-resistant rats and their controls, (2) to investigate whether a positive correlation of IH and plasma homocysteine response occurs following CEA in the insulin-resistant rat model, and (3) if so, to attempt to decrease IH by supplementation with folic acid, a known enzymatic cofactor in the homocysteine metabolic pathway. To achieve these aims, male rats (275 to 300 g) were fed 1 of 4 diets for a 4-month period: (1) high-fat sucrose (HFS), (2) low-fat complex carbohydrate (LFCC), (3) HFS + 25 mg/kg folic acid (HFS+F), or (4) LFCC + 25 mg/kg folic acid (LFCC+F). At the end of the 4-month period the rats underwent an open (non-balloon) unilateral CEA. Two weeks post-endarterectomy, blood, liver and carotid tissue were removed to measure plasma insulin, folic acid, and homocysteine, 2 key enzymes of homocysteine metabolism-methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS)-and percent lumenal stenosis (IH%). Computer-assisted morphometric analysis was used to measure the percentage of IH in the carotid artery. Plasma homocysteine was significantly higher in the HFS group when compared with the LFCC group (11.3+/-1.3 micromol/L v 7.4+/-0.6 mircomol/L, P=.008) as was post-endarterectomy IH producing lumenal stenosis (30.7%+/-4.2% v 14.0%+/-4.3%, P=.008). Plasma insulin in the HFS group was higher than the LFCC (control) group and was significant (36.3+/-3.0 microU/mL v 21.1+/-0.8 microU/mL, P=.0004). Folic acid supplementation in the HFS group resulted in reductions of plasma homocysteine (HFS v HFS+F, 11.3+/-1.3 micromol/L v 7.95+/-1.0 micromol/L, P=.02) and post-endarterectomy IH (HFS v HFS+F, 30.7%+/-4.2 % v 10.4%+/-1.6%, P=.0001). The control or LFCC group was not statistically different from the HFS+F group in homocysteine or IH. Folate supplementation did not decrease insulin concentrations in the HFS+F group compared to the LFCC group. We conclude that the HFS diet produced an insulin-resistant state with an elevated plasma homocysteine and an exaggerated IH response following carotid endarterectomy in this rat model. Dietary folate supplementation reduced plasma homocysteine concentrations in the HFS diet, which implicates hyperhomocysteinemia as an etiologic factor in the development of post-CEA IH in this insulin-resistant rat model.

Cytochrome P450 phenotypic ratios for predicting herb-drug interactions in humans.

OBJECTIVES: Phytochemical-mediated modulation of cytochrome P450 (CYP) activity may underlie many herb-drug interactions. Single-time point phenotypic metabolic ratios were used to determine whether long-term supplementation of St John's wort, garlic oil, Panax ginseng, and Ginkgo biloba affected CYP1A2, CYP2D6, CYP2E1, or CYP3A4 activity. METHODS: Twelve healthy volunteers (6 females) were randomly assigned to receive either St John's wort, garlic oil, P ginseng, or G biloba for 28 days. For each subject, a 30-day washout period was interposed between each supplementation phase. Probe-drug cocktails of midazolam, caffeine, chlorzoxazone, and debrisoquin (INN, debrisoquine) were administered before supplementation (baseline) and at the end of supplementation. Presupplementation and postsupplementation phenotypic trait measurements were determined for CYP3A4, CYP1A2, CYP2E1, and CYP2D6 with the use of 1-hydroxymidazolam/midazolam serum ratios (1-hour sample), paraxanthine/caffeine serum ratios (6-hour sample), 6-hydroxychlorzoxazone/chlorzoxazone serum ratios (2-hour sample), and debrisoquin urinary recovery ratios (8-hour collection), respectively. RESULTS: Comparisons of presupplementation and postsupplementation ratios indicated that St John's wort significantly induced the activity of CYP2E1 and CYP3A4 (P <.0001). Among female subjects, St John's wort produced significantly greater increases in CYP3A4 phenotypic ratios that appeared to be unrelated to body mass index. This finding is suggestive of a sexual dimorphism in CYP3A4 inducibility. Garlic oil reduced CYP2E1 activity by 39% (P =.030), whereas no significant effect on CYP activity was observed for P ginseng and G biloba. CONCLUSIONS: Single-time point phenotypic metabolic ratios may provide a practical means of predicting CYP-mediated herb-drug interactions in humans.