Increased frequency and quantity of mucosal and plasma cytomegalovirus replication among Ugandan Adults Living with HIV.

BACKGROUND: Co-infection with HIV can result in impaired control of cytomegalovirus (CMV) replication, increasing the likelihood of disease and onward transmission. The objective of this analysis was to measure the impact of HIV on CMV replication in an intensively-sampled cohort in Kampala, Uganda. METHODS: CMV seropositive men and women aged 18-65, with or without HIV co-infection, were followed for one month. Daily oral swabs and weekly anogenital swabs and plasma were collected. Quantitative CMV PCR was performed on all samples. RESULTS: Eighty-five participants were enrolled and provided ≥1 oral swab; 43 (51%) were HIV-seropositive. People living with HIV (PLWH; median CD4 count 439 cells/mm3; none on antiretrovirals) had 2-4 times greater risk of CMV detection at each anatomical site assessed. At the oral site, 773 of 1272 (61%) of samples from PLWH had CMV detected, compared to 214 of 1349 (16%) among people without HIV. Similarly, the mean CMV quantity was higher among PLWH at all anatomical sites, with the largest difference seen for oral swabs (mean difference 1.63 log/mL; 95% CI 1.13-2.13). Among PLWH, absolute quantity of CD4+ T-cells was not associated with risk of CMV detection. HIV plasma RNA quantity was positively correlated with oral CMV shedding frequency, but not detection at other sites. CONCLUSIONS: Mucosal and systemic CMV replication occurs at higher levels in PLWH than people without HIV, particularly oral shedding, which is a major mode of CMV transmission. Increased CMV replication despite relatively preserved CD4+ T-cell counts suggests that additional interventions are required to improve CMV control in PLWH.

Oral HHV-8 replication among women in Mombasa, Kenya.

Human herpesvirus-8 (HHV-8) replication in the oropharynx may play an important role in HHV-8 transmission and contribute to the development of Kaposi sarcoma (KS) in some individuals. Studies in the United States and Europe report high rates of HHV-8 DNA detection in saliva of HHV-8 infected men, but little is known about the natural history of HHV-8 among persons in sub-Saharan Africa, where prevalence of HHV-8 infection and KS is greatest. To address this gap, this study evaluated oral HHV-8 replication in a cohort of 40 HHV-8 seropositive Kenyan women. Study clinicians collected daily oral swabs from participants for up to 30 consecutive days, and swab samples were tested for HHV-8 DNA using quantitative, real-time polymerase chain reaction. HHV-8 was detected at least once in 27 (68%) participants, and the overall shedding rate was 23%. On days with HHV-8 detection, mean HHV-8 quantity was 4.5 log10 copies/ml. Among HIV-infected women, CD4 count ≥500 cells/mm(3) versus <500 cells/mm(3) was associated with higher HHV-8 copy number (4.8 log10 copies/ml vs. 3.4 log10 copies/ml; coef 1.2 [95% CI, 0.5-1.9]; P = 0.001) and a higher HHV-8 shedding rate (49% vs.12%; RR, 4.2 [95% CI, 0.8-21.4]; P = 0.08). No other factors were associated with HHV-8 shedding rate or copy number. The study demonstrates high rates and quantity of HHV-8 in the oropharynx of HHV-8 seropositive African women. These findings support the observation that oral replication is an essential feature of HHV-8 infection, with likely implications for HHV-8 transmission and KS pathogenesis.

High-dose valacyclovir decreases plasma HIV-1 RNA more than standard-dose acyclovir in persons coinfected with HIV-1 and HSV-2: a randomized crossover trial.

BACKGROUND: Standard doses of herpes simplex virus (HSV) suppressive therapy reduce plasma HIV-1 RNA levels (0.25-0.53 log10 copies per milliliter) among HIV-1/HSV-2 coinfected persons. Postulated mechanisms for this effect include direct inhibition of HIV-1 by acyclovir or indirect reduction by decreasing HSV-associated inflammation. We hypothesized that high-dose valacyclovir would further reduce plasma HIV-1 RNA and that the effect would be mediated by greater suppression of HSV shedding. METHODS: Thirty-four participants with HIV-1 and HSV-2 not on antiretroviral therapy were enrolled into a randomized, open-label crossover trial of valacyclovir 1000 mg twice daily or acyclovir 400 mg twice daily for 12 weeks, followed by a 2-week washout, and then the alternate treatment arm for 12 weeks. HSV DNA was measured from daily self-collected genital swabs for the initial 4 weeks of each arm, and HIV-1 RNA was quantified from weekly plasma samples. RESULTS: Twenty-eight participants provided plasma samples and genital swabs on both acyclovir and valacyclovir. The genital HSV-2 shedding rate was the same on valacyclovir and acyclovir [7.8% vs. 8.2% of days; relative risk: 0.95; 95% confidence interval (CI): 0.66 to 1.37; P = 0.78]. Plasma HIV-1 RNA was 0.27 log10 copies per milliliter lower on valacyclovir compared with acyclovir (95% CI: -0.41 to -0.14 log10 copies per milliliter; P < 0.001); this was unchanged after adjustment for genital HSV-2 shedding. CONCLUSIONS: High-dose valacyclovir reduces plasma HIV-1 RNA levels more than standard-dose acyclovir in HIV-1/HSV-2-seropositive persons not receiving antiretroviral therapy. The incremental reduction in plasma HIV-1 RNA achieved is not mediated by greater genital HSV-2 suppression.

A prospective cohort study of partner testing for herpes simplex virus and sexual behavior during pregnancy.

BACKGROUND: We investigated whether serotesting sexual partners of pregnant women for herpes simplex virus (HSV) improves adherence to safer-sex practices. METHODS: A total of 287 HSV-2-seronegative pregnant women were recruited, and their partners were invited for HSV serologic testing. On the basis of test results, women were placed into 4 groups: those at risk for HSV-2 infection, those at risk for HSV-1 infection, those whose partner was not tested, and those not at risk for HSV infection. Women received safer-sex counseling and completed diaries of sexual activity. RESULTS: Women in HSV-2-serodiscordant couples (ie, those in relationships in which they were at risk for HSV-2 acquisition) reported a smaller percentage of days with unprotected genital sex acts as compared to women who were not at risk (2% vs 8%; relative risk [RR], 0.3 [95% confidence interval {CI}, .1-.8]; P = .002) and to women whose partners' HSV status was unknown (2% vs 11%; RR, 0.2 [95% CI, .1-.8]; P = .02). Women in HSV-1-serodiscordant couples showed no difference in the frequency of genital sex acts, unprotected genital sex acts, or oral sex acts as compared to those not at risk and to those whose partners' status was unknown. CONCLUSIONS: Pregnant women at known risk of HSV-2 acquisition by partner serotesting were less likely to engage in unprotected genital sex acts than HSV-2-seronegative women with partners who were negative or not tested.

Extravaginal reservoirs of vaginal bacteria as risk factors for incident bacterial vaginosis.

BACKGROUND: Bacterial vaginosis (BV) represents shifts in microbiota from Lactobacillus spp. to diverse anaerobes. Although antibiotics relieve symptoms and temporarily eradicate BV-associated bacteria (BVAB), BV usually recurs. We investigated the role of extravaginal BVAB reservoirs in recurrence. METHODS: Risks for BV acquisition over the course of 1 year were defined. DNA in vaginal, anal, and oral swab samples from enrollment was subjected to quantitative polymerase chain reaction assays targeting 16S ribosomal RNA genes of Gardnerella vaginalis, Lactobacillus crispatus, BVAB1, BVAB2, BVAB3, Megasphaera spp., Lactobacillus jensenii, and Leptotrichia/Sneathia spp. A case-control approach analyzed BVAB detection at enrollment for case patients (BV acquisition) versus controls (none). RESULTS: Of 239 women enrolled without BV, 199 were seen in follow-up, and 40 experienced BV; 15 had all samples for analysis. Detection of G. vaginalis in oral cavity or anal samples and Leptotrichia/Sneathia spp. in anal samples was more common at enrollment among case patients, who also had higher concentrations of these bacteria and Megasphaera relative to 30 controls at each site. In contrast, L. crispatus was detected more frequently in anal samples among controls. CONCLUSIONS: Women who acquire BV are more likely have previous colonization of extravaginal reservoirs with some BVAB, and less likely to have L. crispatus, suggesting that BVAB may be acquired vaginally from extravaginal reservoirs.

Standard-dose and high-dose daily antiviral therapy for short episodes of genital HSV-2 reactivation: three randomised, open-label, cross-over trials.

BACKGROUND: Skin and mucosal herpes simplex virus type 2 (HSV-2) shedding predominantly occurs in short subclinical episodes. We assessed whether standard-dose or high-dose antiviral therapy reduces the frequency of such shedding. METHODS: HSV-2-seropositive, HIV-seronegative people were enrolled at the University of Washington Virology Research Clinic (WA, USA). We did three separate but complementary open-label cross-over studies comparing no medication with aciclovir 400 mg twice daily (standard-dose aciclovir), valaciclovir 500 mg daily (standard-dose valaciclovir) with aciclovir 800 mg three times daily (high-dose aciclovir), and standard-dose valaciclovir with valaciclovir 1 g three times daily (high-dose valaciclovir). The allocation sequence was generated by a random number generator. Study drugs were supplied in identical, numbered, sealed boxes. Study periods lasted 4-7 weeks, separated by 1 week wash-out. Participants collected genital swabs four times daily for quantitative HSV DNA PCR. Clinical data were masked from laboratory personnel. The primary endpoint was within-person comparison of shedding rate in each study group. Analysis was per protocol. The trials are registered at ClinicalTrials.gov (NCT00362297, NCT00723229, NCT01346475). RESULTS: Of 113 participants randomised, 90 were eligible for analysis of the primary endpoint. Participants collected 23 605 swabs; 1272 (5·4%) were HSV-positive. The frequency of HSV shedding was significantly higher in the no medication group (n=384, 18·1% of swabs) than in the standard-dose aciclovir group (25, 1·2%; incidence rate ratio [IRR] 0·05, 95% CI 0·03-0·08). High-dose aciclovir was associated with less shedding than standard-dose valaciclovir (198 [4·2%] vs 209 [4·5%]; IRR 0·79, 95% CI 0·63-1·00). Shedding was less frequent in the high-dose valaciclovir group than in the standard-dose valaciclovir group (164 [3·3%] vs 292 [5·8%]; 0·54, 0·44-0·66). The number of episodes per person-year did not differ significantly for standard-dose valaciclovir (22·6) versus high-dose aciclovir (20·2; p=0·54), and standard-dose valaciclovir (14·9) versus high-dose valaciclovir (16·5; p=0·34), but did for no medication (28·7) and standard-dose aciclovir (10·0; p=0·001). Median episode duration was longer for no medication than for standard-dose aciclovir (13 h vs 7 h; p=0·01) and for standard-dose valaciclovir than for high-dose valaciclovir (10 h vs 7 h; p=0·03), but did not differ significantly between standard-dose valaciclovir and high-dose aciclovir (8 h vs 8 h; p=0·23). Likewise, maximum log(10) copies of HSV detected per mL was higher for no medication than for standard dose aciclovir (3·3 vs 2·9; p=0·02), and for standard-dose valaciclovir than for high-dose valaciclovir (2·5 vs 3·0; p=0·001), but no significant difference was recorded for standard-dose valaciclovir versus high-dose aciclovir (2·7 vs 2·8; p=0·66). 80% of episodes were subclinical in all study groups. Except for a higher frequency of headaches with high-dose valaciclovir (n=13, 30%) than with other regimens, all regimens were well tolerated. INTERPRETATION: Short bursts of subclinical genital HSV reactivation are frequent, even during high-dose antiherpes therapy, and probably account for continued transmission of HSV during suppressive antiviral therapy. More potent antiviral therapy is needed to eliminate HSV transmission. FUNDING: NIH. Valaciclovir was provided for trial 3 for free by GlaxoSmithKline.

Treatment with valacyclovir, famciclovir, or antiretrovirals reduces human herpesvirus-8 replication in HIV-1 seropositive men.

Human herpesvirus-8 (HHV-8) replication is a key factor in Kaposi sarcoma, primary effusion lymphoma, and Castleman disease pathogenesis. In vitro data suggest that antivirals inhibit HHV-8 replication, but little data exist in humans. Daily oropharyngeal swabs were analyzed from HIV/HHV-8 dually infected men enrolled in three previous clinical trials of valacyclovir and famciclovir for HIV-1 and/or HSV-2 suppression. Fifty-eight participants contributed 6,036 swabs. HHV-8 was detected in 1,128 (19%) of 6,036 swabs, including 618 (21%) of 2,992 on placebo, 323 (15%) of 2,221 on valacyclovir, and 187 (23%) of 823 on famciclovir. After adjusting for baseline HIV viral load and highly active antiretroviral therapy (HAART) use, an 18% reduction in HHV-8 shedding frequency (IRR 0.822; P = 0.011) was found in participants on valacyclovir and a 30% reduction (IRR 0.700; P < 0.001) on famciclovir. HAART was associated with an 89% (IRR 0.129; P = 0.048) reduction in HHV-8-shedding. Neither antiviral nor antiretroviral therapy was associated with decreased HHV-8 quantity. Valacyclovir and famciclovir were associated with modest but significant reductions in HHV-8 oropharyngeal shedding frequency. In contrast, HAART was a potent inhibitor of HHV-8 replication. Studies of whether antiviral therapy in combination with ART will prevent HHV-8-associated disease appear warranted.

Clinician and patient recognition of anogenital herpes disease in HIV positive men who have sex with men.

Anogenital ulcers caused by herpes simplex virus type 2 (HSV-2) are associated with an increased risk of human immunodeficiency virus (HIV) transmission. When compared with clinician examination, HIV/HSV-2 coinfected men who have sex with men are frequently unaware of anogenital ulcers. These data highlight the importance of condom use and the need for new HSV-2 prevention strategies.

Determinants of aspirin metabolism in healthy men and women: effects of dietary inducers of UDP-glucuronosyltransferases.

BACKGROUND/AIMS: Interindividual variation in aspirin (ASA) metabolism is attributed to concomitant use of drugs or alcohol, urine pH, ethnicity, sex, and genetic variants in UDP-glucuronosyltransferases (UGT). Little is known about the effects of diet. METHODS: We evaluated cross-sectionally whether urinary excretion of ASA and its metabolites [salicylic acid (SA), salicyluric acid (SUA) phenolic glucuronide (SUAPG), salicylic acid acyl glucuronide (SAAG) and salicylic acid phenolic glucuronide (SAPG)] differed by UGT1A6 genotype and dietary factors shown to induce UGT. Following oral treatment with 650 mg ASA, urine was collected over 8 h in 264 men and 264 women (21-45 years old). RESULTS: There were statistically significant differences in metabolites excreted between sexes and ethnicities. Men excreted more SUA; women more ASA (p = 0.03), SA, SAAG and SAPG (p ≤ 0.001 for all). Compared to Caucasians, Asians excreted more ASA, SA and SAAG, and less SUA and SUAPG (p ≤ 0.03 for all); African-Americans excreted more SAAG and SAPG and less SUA (p ≤ 0.04). There was no effect of UGT1A6 genotypes. Increased ASA and decreased SUAPG excretion was observed with increased servings of vegetables (p = 0.008), specifically crucifers (p = 0.05). CONCLUSION: Diet may influence the pharmacokinetics of ASA, but effects may be through modulation of glycine conjugation rather than glucuronidation.

The effects of daily distress and personality on genital HSV shedding and lesions in a randomized, double-blind, placebo-controlled, crossover trial of acyclovir in HSV-2 seropositive women.

Herpes simplex virus (HSV) infections are ubiquitous in humans, but the determinants of clinical and virologic severity are not completely understood. Prior research has suggested that psychological distress can be a co-factor in reactivation of latent HSV infection. Personality traits such as extraversion and neuroticism influence stress attributions and may inform the relationship between psychological distress and health outcomes. Earlier studies in this area have primarily focused on subjective reports of HSV lesion recurrence, but such reports may be influenced by both personality traits and distress. We report results from a randomized, double-blind, placebo-controlled, crossover trial of acyclovir in 19 women for whom personality was assessed at baseline and daily assessments of genital lesions, stress, anxiety, and depression levels were collected for 22 weeks. In addition, daily swabs of the genital mucosa were collected to assess HSV-2 viral reactivation. We found that daily stress predicted genital lesion frequency, and that daily stress, anxiety, and depression predicted genital lesion onset approximately 5 days before onset. Anxiety was also associated with genital lesions 3 days after onset. Distress and viral reactivation were not associated; and no personality traits were associated with any of the outcomes. These results support the hypothesis that psychological distress is both a cause and a consequence of genital lesion episodes.

Persistent genital herpes simplex virus-2 shedding years following the first clinical episode.

BACKGROUND: Patients with newly acquired genital herpes simplex virus 2 (HSV-2) infection have virus frequently detected at the genital mucosa. Rates of genital shedding initially decrease over time after infection, but data on long-term viral shedding are lacking. METHODS: For this study, 377 healthy adults with history of symptomatic genital HSV-2 infection collected anogenital swabs for HSV-2 DNA polymerase chain reaction for at least 30 consecutive days. RESULTS: Time since first genital herpes episode was significantly associated with reduced genital shedding. Total HSV shedding occurred on 33.6% of days in participants <1 year, 20.6% in those 1-9 years, and 16.7% in those ≥10 years from first episode. Subclinical HSV shedding occurred on 26.2% of days among participants <1 year, 13.1% in those 1-9 years, and 9.3% in those ≥10 years from first episode. On days with HSV detection, mean quantity was 4.9 log10 copies/mL for those <1 year, 4.7 log10 copies/mL among those 1-9 years, and 4.6 log10 copies/mL among those ≥10 years since first episode. CONCLUSIONS: Rates of total and subclinical HSV-2 shedding decrease after the first year following the initial clinical episode. However, viral shedding persists at high rates and copy numbers years after infection, and therefore may pose continued risk of HSV-2 transmission to sexual partners.

Gender differences in clinical presentation and outcomes of epidemic Kaposi sarcoma in Uganda.

INTRODUCTION: The incidence of Kaposi sarcoma (KS) has increased dramatically among women in sub-Saharan Africa since the onset of the HIV pandemic, but data on KS disease in women are limited. To identify gender-related differences in KS presentation and outcomes, we evaluated the clinical manifestations and response in men and women with AIDS-associated KS in Uganda. METHODS AND FINDINGS: HIV-infected adults with KS attending the Infectious Diseases Institute (IDI) and Uganda Cancer Institute (UCI) in Kampala, Uganda between 2004 and 2006 were included in a retrospective cohort. Evaluation of KS presentation was based on the clinical features described at the initial KS visit. Response was evaluated as the time to "improvement", as defined by any decrease in lesion size, lesion number, or edema. The cohort consisted of 197 adults with HIV and KS: 55% (108/197) were women. At presentation, the median CD4 T-cell count was significantly lower in women (58 cells/mm(3); IQR 11-156 cells/mm(3)) than men (124 cells/mm(3); IQR 22-254 cells/mm(3)) (p = 0.02). Women were more likely than men to present with lesions of the face (OR 2.8, 95% CI, 1.4, 5.7; p = 0.005) and hard palate (OR 2.0, 95% CI, 1.1, 3.7; p = 0.02), and were less likely than men to have lower extremity lesions (OR 0.54, 95% CI, 0.3, 0.99; p = 0.05). Women were less likely than men to demonstrate clinical improvement (HR = 0.52, CI 0.31, 0.88; p = 0.01) in multivariate analysis. CONCLUSIONS: The clinical presentation and response of KS differs between men and women in Uganda. These data suggest that gender affects the pathophysiology of KS, which may have implications for the prevention, diagnosis, and treatment of KS in both men and women. Prospective studies are needed to identify predictors of response and evaluate efficacy of treatment in women with KS, particularly in Africa where the disease burden is greatest.

DNA vaccine delivery by densely-packed and short microprojection arrays to skin protects against vaginal HSV-2 challenge.

There is an unmet medical need for a prophylactic vaccine against herpes simplex virus (HSV). DNA vaccines and cutaneous vaccination have been tried for many applications, but few reports combine this vaccine composition and administration route. We compared DNA administration using the Nanopatch™, a solid microprojection device coated with vaccine comprised of thousands of short (110 µm) densly-packed projections (70 µm spacing), to standard intramuscular DNA vaccination in a mouse model of vaginal HSV-2 infection. A dose-response relationship was established for immunogenicity and survival in both vaccination routes. Appropriate doses administered by Nanopatch™ were highly immunogenic and enabled mouse survival. Vaginal HSV-2 DNA copy number day 1 post challenge correlated with survival, indicating that vaccine-elicited acquired immune responses can act quickly and locally. Solid, short, densely-packed arrays of microprojections applied to the skin are thus a promising route of administration for DNA vaccines.

Citrus fruit intake is associated with lower serum bilirubin concentration among women with the UGT1A1*28 polymorphism.

UDP-glucuronosyltransferase (UGT) 1A1 glucuronidates bilirubin, estrogens, and xenobiotic compounds. The UGT1A1*28 polymorphism results in lower promoter activity due to 7 thymine-adenine (TA) repeats rather than the more common 6 TA repeats. Previously, we showed that serum bilirubin, a marker of UGT1A1 activity, was lower among individuals homozygous for the UGT1A1*28 polymorphism (7/7) when randomized to a high fruit and vegetable (F&V) diet, whereas there was no effect in individuals with the wild-type (6/6) and heterozygous (6/7) genotypes. Our objective here was to determine if we could detect genotype x diet interactions on bilirubin concentrations in an observational study. Healthy nonsmoking men (n = 146) and women (n = 147), recruited from the Seattle area, provided blood samples for genotyping and bilirubin measurements. We used multiple linear regression to assess the relationships among UGT1A1 genotype, bilirubin concentrations, and consumption of specific F&V [cruciferous vegetables, citrus fruits, and soy foods (n = 268)] based on FFQ and F&V from 6 botanical families [Cruciferae, Rosaceae, Rutaceae, Umbelliferae, Solanaceae, and Leguminosae (n = 261)] based on 3-d food records. We observed a significant interaction of UGT1A1 genotype and citrus consumption among women. Women with the 7/7 genotype who consumed > or = 0.5 daily servings of citrus fruit or foods from the Rutaceae botanical family had approximately 30% lower serum bilirubin than those with the same genotype who consumed less, whereas 6/6 and 6/7 genotypes did not differ by consumption (P for interaction = 0.006 and 0.03, respectively). These results suggest that citrus consumption may increase UGT1A1 activity among women with the 7/7 genotype.

Impact of HIV infection and Kaposi sarcoma on human herpesvirus-8 mucosal replication and dissemination in Uganda.

INTRODUCTION: Kaposi sarcoma (KS) is the leading cause of cancer in Uganda and occurs in people with and without HIV. Human herpesvirus-8 (HHV-8) replication is important both in transmission of HHV-8 and progression to KS. We characterized the sites and frequency of HHV-8 detection in Ugandans with and without HIV and KS. METHODS: Participants were enrolled into one of four groups on the basis of HIV and KS status (HIV negative/KS negative, HIV positive/KS negative, HIV negative/KS positive, and HIV positive/KS positive). Participants collected oral swabs daily and clinicians collected oral swabs, anogenital swabs, and plasma samples weekly over 4 weeks. HHV-8 DNA at each site was quantified by polymerase chain reaction (PCR). RESULTS: 78 participants collected a total of 2063 orals swabs and 358 plasma samples. Of these, 428 (21%) oral swabs and 96 (27%) plasma samples had detectable HHV-8 DNA. HHV-8 was detected more frequently in both the oropharynx of persons with KS (24 (57%) of 42 persons with KS vs. 8 (22%) of 36 persons without, p = 0.002) and the peripheral blood (30 (71%) of 42 persons with KS vs. 8 (22%) of 36 persons without, p<0.001). In a multivariate model, HHV-8 viremia was more frequent among men (IRR = 3.3, 95% CI = 1.7-6.2, p<0.001), persons with KS (IRR = 3.9, 95% CI = 1.7-9.0, p = 0.001) and persons with HIV infection (IRR = 1.7, 95% CI = 1.0-2.7, p = 0.03). Importantly, oral HHV-8 detection predicted the subsequent HHV-8 viremia. HHV-8 viremia was significantly more common when HHV-8 DNA was detected from the oropharynx during the week prior than when oral HHV-8 was not detected (RR = 3.3, 95% CI = 1.8-5.9 p<0.001). Genital HHV-8 detection was rare (9 (3%) of 272 swabs). CONCLUSIONS: HHV-8 detection is frequent in the oropharynx and peripheral blood of Ugandans with endemic and epidemic KS. Replication at these sites is highly correlated, and viremia is increased in men and those with HIV. The high incidence of HHV-8 replication at multiple anatomic sites may be an important factor leading to and sustaining the high prevalence of KS in Uganda.

Phytochemical regulation of UDP-glucuronosyltransferases: implications for cancer prevention.

Uridine 5'-diphospho-glucuronosyltransferases (UGTs) are Phase II biotransformation enzymes that metabolize endogenous and exogenous compounds, some of which have been associated with cancer risk. Many phytochemicals have been shown to induce UGTs in humans, rodents, and cell culture systems. Because UGTs maintain hormone balance and facilitate excretion of potentially carcinogenic compounds, regulation of their expression and activity may affect cancer risk. Phytochemicals regulate transcription factors such as the nuclear factor-erythroid 2-related factor 2 (Nrf2), aryl hydrocarbon, and pregnane X receptors as well as proteins in several signal transduction cascades that converge on Nrf2 to stimulate UGT expression. This induction can be modified by several factors, including phytochemical dose and bioavailability and interindividual variation in enzyme expression. In this review, we summarize the knowledge of dietary modulation of UGTs, particularly by phytochemicals, and discuss the potential mechanisms by which phytochemicals regulate UGT transcription.

Identification of residues that contribute to receptor activation through the analysis of compensatory mutations in the G protein-coupled alpha-factor receptor.

The alpha-factor receptor (Ste2p) stimulates mating of the yeast Saccharomyces cerevisiae. Ste2p belongs to the large family of G protein-coupled receptors that are characterized by seven transmembrane alpha-helices. Receptor activation is thought to involve changes in the packing of the transmembrane helix bundle. To identify residues that contribute to Ste2p activation, second-site suppressor mutations were isolated that restored function to defective receptors carrying either an F204S or Y266C substitution which affect residues at the extracellular ends of transmembrane domains 5 and 6, respectively. Thirty-five different suppressor mutations were identified. On their own, these mutations caused a range of phenotypes, including hypersensitivity, constitutive activity, altered ligand binding, and loss of function. The majority of the mutations affected residues in the transmembrane segments that are predicted to face the helix bundle. Many of the suppressor mutations caused constitutive receptor activity, suggesting they improved receptor function by partially restoring the balance between the active and inactive states. Analysis of mutations in transmembrane domain 7 implicated residues Ala281 and Thr282 in receptor activation. The A281T and T282A mutants were supersensitive to S. cerevisiae alpha-factor, but were defective in responding to a variant of alpha-factor produced by another species, Saccharomyces kluyveri. The A281T mutant also displayed 8.7-fold enhanced basal signaling. Interestingly, Ala281 and Thr282 are situated in approximately the same position as Lys296 in rhodopsin, which is covalently linked to retinal. These results suggest that transmembrane domain 7 plays a role in receptor activation in a wide range of G protein-coupled receptors from yeast to humans.