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Fusicoccane (FC)-type diterpenoids are a class of diterpenoids characterized by a unique 5-8-5 ring system and exhibit diverse biological activities. Recently, we identified a novel FC-type diterpene synthase MgMS, which produces a myrothec-15(17)-en-7-ol (1) hydrocarbon skeleton, however, its tailoring congeners have not been elucidated. Here, we discovered two additional gene clusters Bn and Np, each encoding a highly homologous terpene synthase to MgMS but distinct tailoring enzymes. Heterologous expression of the terpene synthases BnMS and NpMS yielded the same product as MgMS. Subsequent introduction of three P450 enzymes MgP450, BnP450 and NpP450 from individual gene clusters resulted in four new FC-type diterpenoids 2-5. Notably, MgP450 serves as the first enzyme responsible for hydroxylation of the C19 methyl group, whereas NpP450 functions as a multifunctional P450 enzyme involved in the oxidations at C5, C6, and C19 positions of the 5-8-5 tricyclic skeleton. C5 oxidation of the hydrocarbon skeleton 1 led to broadening of the NMR signals and incomplete spectra, which was resolved by high-temperature NMR spectral analysis.

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Preexposure prophylaxis (PrEP) is not available in China and the willingness to use PrEP among Chinese men who have sex with men (MSM) is not clear. The aim of this study was to better understand the association between PrEP comprehension and the willingness to use PrEP under varying conditions among MSM. An online survey investigating personal characteristics, PrEP comprehension, and PrEP willingness among MSM was conducted. A third of respondents (36.2%, 196 out of 541) reported that they would like to use PrEP. Compared with MSM with a basic level of PrEP comprehension, MSM with a high level were more likely to report clear choices: a willingness or unwillingness to use PrEP (82.4% versus 65.7%, p <0.01). Among 350 MSM willing to use PrEP or uncertain about uptake, those with a high level of PrEP comprehension were more likely to use PrEP daily (adjusted odds ratio [AOR] = 1.71, 95% confidence interval 1.04-2.80), and to use PrEP with mild or other side effects (AOR = 2.72 or 2.77). A high level of PrEP comprehension is a key factor in urging MSM to use PrEP under varying conditions. Our findings call attention to the need for health education to improve PrEP comprehension.

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BACKGROUND: China faces a serious HIV epidemic among men who have sex with men (MSM), and a large proportion of new infections are attributed to their regular male sex partners (RP). The objective of this study was to investigate the association between intimate relationship characteristics and HIV-related behaviors among MSM with RP in Guangzhou, China. METHODS: A convenience-sampling method was used in data collection. A total of 608 MSM were screened, of whom 406 HIV negative MSM with at least one RP in the past six months were used for data analysis. Three-step logistic regressions were used to analyze the data. RESULTS: The prevalence of unprotected anal intercourse (UAI) with regular male sex partners, non-regular male sex partners, and concurrent UAI in the past six months was 53.9%, 23.6%, 20.7%, respectively. Variables associated with UAI with regular male sex partners included expectations for this relationship (adjusted odds ratio in multiple forward stepwise logistic regression, ORm = 1.66) and open communication about the sexual relationship (ORm = 1.79), while expectations for the relationship (ORm = 0.46 to 0.54) and conflicts of interest (ORm = 5.46 to 5.97) were associated with concurrent UAI and UAI with non-regular male sex partners. CONCLUSION: Intimate relationship characteristics were related to HIV-related risk behaviors. Future HIV prevention interventions should take MSM couples into consideration, include a focus on the quality of their intimate relationships, and encourage open communication about their sexual relationships.

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OBJECTIVE: To develop a human immune deficiency virus (HIV) infection risk appraisal model suitable for men who has sex with men (MSM) in Guangzhou, and to provide tools for follow-up the outcomes on health education and behavior intervention. METHODS: A cros-sectional study was conducted in Guangzhou from 2008 to 2010. Based on the HIV surveillance data, the main risk factors of HIV infection among MSM were screened by means of logistic regression. Degree on relative risk was transformed into risk scores by adopting the statistics models. Individual risk scores, group risk scores and individual infection risk in comparison with usual MSM groups could then be calculated according to the rate of exposure on those risk factors appeared in data from the surveillance programs. RESULTS: Risk factors related to HIV infection among MSM and the quantitative assessment standard (risk scores and risk scores table of population groups) for those factors were set up by multiple logistic regression, including age, location of registered residence, monthly income, major location for finding their sexual partners, HIV testing in the past year, age when having the first sexual intercourse, rate of condom use in the past six months, symptoms related to sexually transmitted diseases (STDs) and syphilis in particular. The average risk score of population was 6.06, with risk scores for HIV positive and negative as 3.10 and 18.08 respectively (P < 0.001). The rates of HIV infection for different score groups were 0.9%, 2.0%, 7.0%, 14.4% and 33.3%, respectively. The sensitivity and specificity on the prediction of scores were 54.4% and 75.4% respectively, with the accuracy rate as 74.2%. CONCLUSION: HIV infection risk model could be used to quantify and classify the individual's infectious status and related factors among MSM more directly and effectively, so as to help the individuals to identify their high-risk behaviors as well as lifestyles. We felt that it could also serve as an important tool used for personalized HIV health education and behavior intervention programs.

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OBJECTIVE: To explore the HIV and syphilis infection and AIDS-related behaviors among money boys (MB) in Guangzhou. METHODS: A total of 152 subjects were recruited from MB gathering place (clubs, parks, Internet etc.) by a local NGO. Of which, 151 individuals completed the investigation and blood sample collection. An anonymous face to face interview were used to obtain data of AIDS-related behavior, knowledge and attitudes. Venous blood samples were collected for HIV and syphilis antibody test. χ(2) test were used to compare the characteristics of HIV and syphilis infection subjects and P < 0.05 was counted as significant. RESULTS: HIV and current syphilis infection rate were 11.3% (17/151) and 19.9% (30/151), respectively. Among the subjects, 47.0% (71/151) had unprotected anal intercourse (UAI) with commercial male sex partners, 43.7% (66/151) had UAI with non-commercial male sex partners in the past six month. 85.4% (129/151) were aware of AIDS-related knowledge, while 34.4% (52/151) thought they have no risk of HIV infection, 24.5% (37/151) didn't know the prevalence of HIV among MSM in China, and 55.0% (83/151) had no idea of HIV prevalence or thought HIV prevalence was not serious at all among MB. MB who had experienced sex after drunk/used drugs had higher proportion of syphilis infection (33.3% vs 16.5%; χ(2) = 4.26, P = 0.039), and who had ever been experiencing condom broken during sex had much higher syphilis infection rate than those didn't (36.7% vs 15.7%; χ(2) = 6.64, P = 0.010). A multi-Logistics regression analysis showed that subjects had ever been experiencing condom broke during sex in the past six month were associated with syphilis infection (χ(2) = 6.24, P = 0.012; OR = 3.11, 95%CI = 1.28 - 7.57). CONCLUSION: Money boys have high prevalence of HIV and syphilis infection. They are lack of perception of HIV risk and active in unsafe sex behavior.

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