Earth system models predict that increases in atmospheric and soil dryness will reduce photosynthesis in the Amazon rainforest, with large implications for the global carbon cycle. Using in situ observations, solar-induced fluorescence, and nonlinear machine learning techniques, we show that, in reality, this is not necessarily the case: In many of the wettest parts of this region, photosynthesis and biomass tend to increase with increased atmospheric dryness, despite the associated reductions in canopy conductance to CO₂ These results can be largely explained by changes in canopy properties, specifically, new leaves flushed during the dry season have higher photosynthetic capacity than the leaves they replace, compensating for the negative stomatal response to increased dryness. As atmospheric dryness will increase with climate change, our study highlights the importance of reframing how we represent the response of ecosystem photosynthesis to atmospheric dryness in very wet regions, to accurately quantify the land carbon sink.

BACKGROUND: Anal squamous intraepithelial lesions (SIL) and cancers are increased in immunocompromised populations. Based upon anatomic and histologic similarities, the cervix is used as the model for anal screening. During cervical colposcopy, acetic acid (AA) and Lugol׳s staining (LS) result in characteristic changes that help distinguish low-grade (L)SIL from high-grade (H)SIL. Lesion characteristics were evaluated for their ability to distinguish anal (a)LSIL from anal (a)HSIL during high-resolution anoscopy after application of AA and LS. METHODS: AA-stained lesions were described using standard cervical colposcopic criteria. LS was then applied and lesions were characterized as Lugol׳s-negative (L−), Lugol׳s-partial (L+/−), or Lugol׳s positive (L+) and then biopsied. Biopsies were characterized as benign, squamous atypia, LSIL or HSIL. RESULTS: 835 anal lesions were analyzed. Sensitivity and positive predictive value (PPV) for aHSIL were highest for characteristics associated with cervical (c)HSIL. L− was independently associated with aHSIL (OR=4.7, 95% CI=3.4–6.7). In multiple logistic regression analysis, significant predictors of aHSIL were flat contour (OR=2.24, 95% CI=1.3–3.8), mosaic pattern (OR=2.0, 95% CI=1.4–2.9), vascular punctation (OR=1.5, 95% CI=1.1–2.1) and L− (OR=2.3, 95% CI=1.5–3.4). L− staining improved the PPV of aHSIL almost twofold in lesions that otherwise had a colposcopic impression of LSIL. CONCLUSIONS: Evaluating acetowhite lesions for contour, surface, vascularity, and LS may maximize the likelihood of identifying aHSIL.

There is some uncertainty whether net ecosystem productivity (NEP) of boreal black spruce forests is positive or negative under current climates and how NEP would change under hypothesized changes in future climates. The mathematical model ecosys was used to examine NEP of a boreal black spruce forest by testing rates of C transfer simulated from an integrated set of scientific hypotheses against rates measured with chamber, micrometeorological, isotopic and allometric techniques at the northern old black spruce site of the Boreal Ecosystem-Atmosphere Study (BOREAS). Daily aggregations of modeled and measured hourly C fluxes indicated that NEP rose with solar radiation if air temperatures remained below 15°C, but declined if air temperatures rose above 20°C. Daily NEP was thus largest under the higher radiation and lower temperatures of June, but declined under the lower radiation and higher temperatures of July and August. Yearly aggregations of modeled hourly C fluxes indicated that under current (1994–1996) climate NEP of the 150 year old northern old black spruce site was about 40 (wood) + 15 (soil) = 55 g C m⁻² yr⁻¹. Moss was estimated to contribute about 0.25 of net primary productivity (NPP) at this site and was thus an important component of ecosystem C exchange. The model was then used to predict changes in NEP at the old northern old black spruce site under the IS92a climate change scenario. After 150 years NEP was predicted to be 120 (wood) minus 10 (soil) = 110 g C m⁻² yr⁻¹. Cumulative gains of C under this scenario were predicted to be 5700 (wood) minus 700 (soil) = 5000 g C m⁻² after 150 years. Gains of wood C would be vulnerable to loss by fire and insects, both of which could also increase under warmer climates.

Objective

HIV-positive MSM are at increased risk of anal human papillomavirus (HPV) infection compared with men in the general population, and little is known about the natural history of anal HPV infection in this population. The objective of this study was to determine the incidence of and risk factors for anal type-specific HPV infection.

Design

Prospective cohort study.

Methods

HIV-positive MSM were evaluated for anal HPV DNA, lifestyle factors, and sexual risk behaviors every 6 months for at least 2 years.

Results

The overall incidence rate of detectable type-specific anal HPV infection was 21.3 per 100 person-years [95% confidence interval (CI) 17.7-25.4] and was 13.3/100 person-years (10.5-16.6) for oncogenic HPV types. The most common incident infections were HPV 18 (3.7/100 person-years) and HPV 16 (3.5/100 person-years). An increased number of recent partners with whom the participant was the receptive partner [odds ratio (OR) 2.9 (1.6-5.1) 8+ partners vs. 0-1], an increased number of new partners in which the participant was the receptive partner [OR 1.03 (1.01-1.1) per partner], an increased number of new oral-anal contact partners in which the participant was the receptive partner [OR 1.1 (1.03-1.1) per partner], and the frequency of receptive anal intercourse [OR 1.1 (1.03-1.1) per act] all significantly increased the odds of incident HPV infection (P ≤ 0.05).

Conclusion

HIV-positive MSM have a high incidence of oncogenic anal HPV infection. Recent receptive anal sexual behaviors, including receptive anal intercourse and receptive oral-anal contact, are the most important risk factors for incident anal HPV infection.

Background

HIV-positive men who have sex with men (MSM) are at high risk of anal cancer compared with the general population. Human papillomavirus (HPV) infection, particularly HPV 16, is causally associated with anal cancer. However, the risk factors for anal HPV 16 infection are poorly understood. We determined the prevalence and risk factors for anal HPV 16 infection in a population of HIV-positive MSM, most of whom were being treated with antiretroviral therapy.

Design

Cross-sectional data from the baseline visit of a 4-year prospective cohort study.

Methods

Three hundred forty-eight HIV-positive MSM were recruited in San Francisco, and they received a detailed sexual behavior risk factor questionnaire. An anal swab was used to collect specimens for HPV type-specific DNA testing using L1 HPV DNA polymerase chain reaction. We used log-binomial multivariable models to determine the risk factors for anal HPV 16 infection.

Results

Ninety-two percent of HIV-positive MSM had at least 1 anal HPV type, 80% had at least 1 oncogenic HPV type, and 42% had HPV 16. Non-Hispanic white race and higher level of education were associated with a decreased risk of HPV 16 infection. A higher number of total male partners was associated with HPV 16 (relative risk: 1.6, 95% confidence interval 1.1 to 2.4, P = 0.01) for 201-1000 partners compared with 1-200. Injection drug use was independently associated with anal HPV 16 infection (relative risk: 1.5, 95% confidence interval 1.2 to 1.9, P = 0.003).

Conclusions

The prevalence of anal HPV infection, including HPV 16, is high in HIV-positive MSM. HIV-positive MSM should be counseled about the risk associated with increased partners and injection drug use.

OBJECTIVE: Human papillomavirus (HPV) vaccination is routinely recommended in HIV-positive men who have sex with men (MSM) aged ≤ 26 years. Levels of previous HPV exposure in older HIV-positive MSM are assumed to be too high to warrant routine HPV vaccination. However, little is known about the prevalence of and risk factors for neutralizing antibody seropositivity to HPV-16 or HPV-18, a key measure of previous exposure to these types. METHODS: Cross-sectional analysis of baseline visit for 296 HIV-positive MSM participating in a prospective cohort study of anal squamous intraepithelial lesions at a university-based research clinic. Participants completed a questionnaire detailing behaviors and medical history. Phlebotomy, anal cytology, HPV DNA testing with quantitation, and high-resolution anoscopy with biopsy were performed. A pseudovirion-based neutralizing antibody assay was used to measure HPV-16 and HPV-18 neutralizing antibodies. RESULTS: One hundred thirty-two of 296 (45%) men were HPV-16 seropositive and 141 of 296 (48%) were HPV-18 seropositive. One hundred seventy-five of 296 (59%) of the men were positive for HPV-16 antibodies or DNA and 167 of 296 (56%) were positive for HPV-18 antibodies or DNA. In multivariable analysis, HPV-16 seropositivity did not correlate with age, years of HIV positivity, CD4 level, or HIV viral load. Significant risk factors included HPV-16 DNA positivity with higher DNA levels (ptrend < 0.001) and higher number of receptive sexual partners in the last year (ptrend = 0.012). CONCLUSIONS: A high proportion of HIV-positive MSM aged >26 years are DNA negative and seronegative to HPV-16 and HPV-18 even when using a sensitive pseudovirion-based neutralizing antibody assay. Prospective studies are needed to determine the clinical- and cost-effectiveness of HPV vaccination in HIV-positive MSM aged >26 years.

The incidence of anal cancer is elevated in human immunodeficiency virus (HIV)-infected men-who-have-sex-with-men (MSM) compared to the general population. Anal high-grade squamous intraepithelial lesions (HSIL) are common in HIV-infected MSM and the presumed precursors to anal squamous cell cancer; however, direct progression of HSIL to anal cancer has not been previously demonstrated. The medical records were reviewed of 138 HIV-infected MSM followed up at the University of California, San Francisco, who developed anal canal or perianal squamous cancer between 1997 and 2011. Men were followed up regularly with digital anorectal examination (DARE), high-resolution anoscopy (HRA) and HRA-guided biopsy. Although treatment for HSIL and follow-up were recommended, not all were treated and some were lost to follow-up. Prevalent cancer was found in 66 men. Seventy-two HIV-infected MSM developed anal cancer while under observation. In 27 men, anal cancer developed at a previously biopsied site of HSIL. An additional 45 men were not analyzed in this analysis due to inadequate documentation of HSIL in relation to cancer location. Of the 27 men with documented progression to cancer at the site of biopsy-proven HSIL, 20 men progressed from prevalent HSIL identified when first examined and seven men from incident HSIL. Prevalent HSIL progressed to cancer over an average of 57 months compared to 64 months for incident HSIL. Most men were asymptomatic, and cancers were detected by DARE. Anal HSIL has clear potential to progress to anal cancer in HIV-infected MSM. Early diagnosis is facilitated by careful follow-up. Carefully controlled studies evaluating efficacy of screening for and treatment of HSIL to prevent anal cancer are needed.

Infectious diseases are a major threat to both managed and wild pollinators. One key question is how the movement or transplantation of honeybee colonies under different management regimes affects honeybee disease epidemiology. We opportunistically examined any persistent effect of colony management history following relocation by characterising the virus abundances of honeybee colonies from three management histories, representing different management histories: feral, low-intensity management, and high-intensity "industrial" management. The colonies had been maintained for one year under the same approximate 'common garden' condition. Colonies in this observational study differed in their virus abundances according to management history, with the feral population history showing qualitatively different viral abundance patterns compared to colonies from the two managed population management histories; for example, higher abundance of sacbrood virus but lower abundances of various paralysis viruses. Colonies from the high-intensity management history exhibited higher viral abundances for all viruses than colonies from the low-intensity management history. Our results provide evidence that management history has persistent impacts on honeybee disease epidemiology, suggesting that apicultural intensification could be majorly impacting on pollinator health, justifying much more substantial investigation.

BACKGROUND: Anal squamous intraepithelial lesions (SIL) and cancers are increased in immunocompromised populations. Based upon anatomic and histologic similarities, the cervix is used as the model for anal screening. During cervical colposcopy, acetic acid (AA) and Lugol׳s staining (LS) result in characteristic changes that help distinguish low-grade (L)SIL from high-grade (H)SIL. Lesion characteristics were evaluated for their ability to distinguish anal (a)LSIL from anal (a)HSIL during high-resolution anoscopy after application of AA and LS. METHODS: AA-stained lesions were described using standard cervical colposcopic criteria. LS was then applied and lesions were characterized as Lugol׳s-negative (L−), Lugol׳s-partial (L+/−), or Lugol׳s positive (L+) and then biopsied. Biopsies were characterized as benign, squamous atypia, LSIL or HSIL. RESULTS: 835 anal lesions were analyzed. Sensitivity and positive predictive value (PPV) for aHSIL were highest for characteristics associated with cervical (c)HSIL. L− was independently associated with aHSIL (OR=4.7, 95% CI=3.4–6.7). In multiple logistic regression analysis, significant predictors of aHSIL were flat contour (OR=2.24, 95% CI=1.3–3.8), mosaic pattern (OR=2.0, 95% CI=1.4–2.9), vascular punctation (OR=1.5, 95% CI=1.1–2.1) and L− (OR=2.3, 95% CI=1.5–3.4). L− staining improved the PPV of aHSIL almost twofold in lesions that otherwise had a colposcopic impression of LSIL. CONCLUSIONS: Evaluating acetowhite lesions for contour, surface, vascularity, and LS may maximize the likelihood of identifying aHSIL.

Objective

Human papillomavirus (HPV) vaccination is routinely recommended in HIV-positive men who have sex with men (MSM) aged ≤ 26 years. Levels of previous HPV exposure in older HIV-positive MSM are assumed to be too high to warrant routine HPV vaccination. However, little is known about the prevalence of and risk factors for neutralizing antibody seropositivity to HPV-16 or HPV-18, a key measure of previous exposure to these types.

Methods

Cross-sectional analysis of baseline visit for 296 HIV-positive MSM participating in a prospective cohort study of anal squamous intraepithelial lesions at a university-based research clinic. Participants completed a questionnaire detailing behaviors and medical history. Phlebotomy, anal cytology, HPV DNA testing with quantitation, and high-resolution anoscopy with biopsy were performed. A pseudovirion-based neutralizing antibody assay was used to measure HPV-16 and HPV-18 neutralizing antibodies.

Results

One hundred thirty-two of 296 (45%) men were HPV-16 seropositive and 141 of 296 (48%) were HPV-18 seropositive. One hundred seventy-five of 296 (59%) of the men were positive for HPV-16 antibodies or DNA and 167 of 296 (56%) were positive for HPV-18 antibodies or DNA. In multivariable analysis, HPV-16 seropositivity did not correlate with age, years of HIV positivity, CD4 level, or HIV viral load. Significant risk factors included HPV-16 DNA positivity with higher DNA levels (ptrend < 0.001) and higher number of receptive sexual partners in the last year (ptrend = 0.012).

Conclusions

A high proportion of HIV-positive MSM aged >26 years are DNA negative and seronegative to HPV-16 and HPV-18 even when using a sensitive pseudovirion-based neutralizing antibody assay. Prospective studies are needed to determine the clinical- and cost-effectiveness of HPV vaccination in HIV-positive MSM aged >26 years.