Xianhong Xie - Academia.edu (original) (raw)

Papers by Xianhong Xie

American journal of obstetrics and gynecology, Jan 30, 2015

HIV seropositive women face high risk for infection with oncogenic types of human papillomaviruse... more HIV seropositive women face high risk for infection with oncogenic types of human papillomaviruses (oncHPV), abnormal Pap tests and precancer, but cervical cancer risk is only modestly increased. HPV16 is highly oncogenic but only weakly associated with HIV-status and immunosuppression, suggesting HPV16 may have a greater innate ability to evade host immune surveillance than other oncHPV types which in turn should result in a greater relative increase in the prevalence of other oncHPV types among women with cervical precancer. To assess whether the under-representation of HPV16 among HIV-seropositive relative to HIV-seronegative women remains among those with cervical precancers. HIV seropositive and seronegative women in the Women's Interagency HIV Study were screened for cervical intraepithelial neoplasia grade 3 or worse (CIN3+). DNA from >40 HPV types was detected by PCR in cervicovaginal lavage specimens obtained at the visit at which CIN3+ was diagnosed. HPV16 was detec...

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, Jan 17, 2015

Determining cervical precancer risk amongst HIV-infected women who despite a normal Pap test are... more Determining cervical precancer risk amongst HIV-infected women who despite a normal Pap test are oncogenic human papillomavirus (oncHPV)-positive is important for setting screening practices. 2,791 HIV-infected and 975 HIV-uninfected women in the Women's Interagency HIV Study were followed semiannually with Pap tests and colposcopy. Cumulative risks of cervical intraepithelial neoplasia 2 or greater (CIN-2+; threshold used for CIN treatment) and CIN-3+ (threshold to set screening practices) were measured in HIV-infected and HIV-uninfected women with normal Pap tests, stratified by baseline HPV results, and also in HIV-infected women with a low-grade squamous intraepithelial lesion (LSIL; benchmark indication for colposcopy). At baseline, 1,021 HIV-infected and 518 HIV-uninfected women had normal Pap tests, of whom 154 (15%) and 27 (5%), respectively, tested oncHPV-positive. The 5-year CIN-2+ cumulative risk in the HIV-infected oncHPV-positive women was 22% (95% CI, 9%-34%), 1...

JAIDS Journal of Acquired Immune Deficiency Syndromes, 2015

Clinical Cancer Research, 2014

Purpose: It is increasingly relevant to better define what constitutes an adequate surgical margi... more Purpose: It is increasingly relevant to better define what constitutes an adequate surgical margin in an effort to improve reconstructive longevity and functional outcomes following osteosarcoma surgery. Additionally, non-union remains a challenging problem in some patients following allograft reconstruction. Bone Morphogenetic Protein-2 (BMP-2) could enhance osseous union, but has been historically avoided due to concerns that it may promote tumor recurrence. Experimental Design: An orthotopic xenograft murine model was utilized to describe the natural temporal course of osteosarcoma growth. Tumors were treated either with surgery alone, surgery and single-agent chemotherapy, or surgery and dual-agent chemotherapy to assess the relationship between surgical margin and local recurrence. The effect of BMP-2 on local recurrence was similarly assessed. Results: Osteosarcoma tumor growth was categorized into reproducible phases. Margins greater than 997 μm resulted in local control following surgery alone. Margins greater than 36 μm resulted in local control following surgery and single-agent chemotherapy. Margins greater than 12 μm resulted in local control following surgery and dual-agent chemotherapy. The application of exogenous BMP-2 does not confer an increased risk of local recurrence. Conclusions: This model reliably reproduces the clinical, radiographic, and surgical conditions encountered in human osteosarcoma. It successfully incorporates relevant chemotherapy, further paralleling the human experience. Surgical margins required to achieve local control in osteosarcoma can be reduced using single-agent chemotherapy and further decreased using dual-agent chemotherapy. The application of BMP-2 does not increase local recurrence in this model.

Cancer research, Jan 15, 2015

Adiposity is an established risk factor for postmenopausal breast cancer. Recent data suggest tha... more Adiposity is an established risk factor for postmenopausal breast cancer. Recent data suggest that high insulin levels in overweight women may play a major role in this relationship, due to insulin's mitogenic/antiapoptotic activity. However, whether overweight women who are metabolically healthy (i.e., normal insulin sensitivity) have elevated risk of breast cancer is unknown. We investigated whether overweight women with normal insulin sensitivity [i.e., homeostasis model assessment of insulin resistance (HOMA-IR) index, or fasting insulin level, within the lowest quartile (q1)] have increased breast cancer risk. Subjects were incident breast cancer cases (N = 497) and a subcohort (N = 2,830) of Women's Health Initiative (WHI) participants with available fasting insulin and glucose levels. In multivariate Cox models, metabolically healthy overweight women, defined using HOMA-IR, were not at elevated risk of breast cancer compared with metabolically healthy normal weight wo...

JAIDS Journal of Acquired Immune Deficiency Syndromes, 2014

Hepatitis C virus (HCV) viremia is thought to have broad systemic effects on the cellular immune ... more Hepatitis C virus (HCV) viremia is thought to have broad systemic effects on the cellular immune system that go beyond its impact on just those T cells that are HCV specific. However, previous studies of chronic HCV and circulating T-cell subsets (activation and differentiation phenotypes) in HIV negatives used general population controls, rather than a risk-appropriate comparison group. Studies in HIV positives did not address overall immune status (total CD4⁺ count). We used fresh blood from HIV-positive and at-risk HIV-negative women, with and without chronic HCV, to measure percentages of activated CD4⁺ and CD8⁺ T cells, Tregs, and T-cell differentiation phenotypes (naive, central memory, effector memory (EM), and terminally differentiated effector). This included 158 HIV negatives and 464 HIV positives, of whom 18 and 63, respectively, were HCV viremic. In multivariate models of HIV negatives, HCV viremia was associated with 25% fewer naive CD4⁺ (P = 0.03), 33% more EM CD4⁺ (P = 0.0002), and 37% fewer central memory CD8⁺ (P = 0.02) T cells. Among HIV positives, we observed only 1 of these 3 relationships: higher percentage of EM CD4⁺ among HCV viremic women. Furthermore, the association with EM CD4⁺ among HIV positives was limited to individuals with diminished immune status (total CD4⁺ count ≤500 cells/μL), as were associations of HCV viremia with higher percentages of activated CD4⁺ and Tregs. Among HIV positives with high CD4⁺ count, no significant associations were observed. These data suggest that HCV viremia in HIV negatives is associated with accelerated T-cell differentiation, but among HIV positives, the impact of HCV viremia is less straightforward and varies by total CD4v count.

AIDS, 2014

To estimate the effects of infection by HIV on the type-specific cumulative detection of cervicov... more To estimate the effects of infection by HIV on the type-specific cumulative detection of cervicovaginal infection by human papillomavirus (HPV). Retrospective assessment of prospectively collected data in a multicenter US cohort. HIV-seropositive and at-risk seronegative participants in the Women's Interagency HIV Study were followed semiannually for up to 11 years. HPV typing was determined from cervicovaginal lavage specimens by PCR; types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68 were considered carcinogenic. Among the 3438 women enrolled (2543 HIV-seropositive, 895 seronegative), the cumulative detection of any HPV infection rose among HIV-seropositive women from 53% at baseline to 92% at 8 years, and among seronegative women from 22 to 66% (P < 0.0001 for HIV-seropositive vs. seronegative women). The 8-year cumulative detection of carcinogenic and noncarcinogenic HPV was 67 and 89% among HIV-seropositive, and 36 and 56% among seronegative women (P = 0.001 for both carcinogenic and noncarcinogenic HPV). The 8-year cumulative detection of HPV16 and HPV18 was 15.2 and 15.0% in HIV-seropositive, and 6.7 and 6.1% in HIV-seronegative women (P < 0.0001 for both). In multivariable regression analyses, lower CD4(+) cell count, age under 30 years, and smoking, but not number of lifetime sexual partners, were significant correlates of cumulative HPV detection. More than 90% of the HIV-seropositive women have HPV detected during a long follow-up. The rates are lower among at-risk HIV-seronegative women, though most also develop HPV infections.

Viral Immunology, 2014

Other than CD4+ count, the immunologic factors that underlie the relationship of HIV/AIDS with pe... more Other than CD4+ count, the immunologic factors that underlie the relationship of HIV/AIDS with persistent oncogenic HPV (oncHPV) and cervical cancer are not well understood. Plasmacytoid dendritic cells (pDCs) and regulatory T-cells (Tregs) are of particular interest. pDCs have both effector and antigen presenting activity and, in HIV-positive patients, low pDC levels are associated with opportunistic infections. Tregs downregulate immune responses, and are present at high levels in HIV-positives. The current pilot study shows for the first time that low pDC and high Treg levels may be significantly associated with oncHPV persistence in both HIV-positive and HIV-negative women. Larger studies are now warranted.

Statistics in Medicine, 2012

Statistical approaches for estimating and drawing inference on the correlation between two biomar... more Statistical approaches for estimating and drawing inference on the correlation between two biomarkers that are repeatedly assessed over time and subject to left-censoring because minimum detection levels are lacking. We propose a linear mixed-effects model and estimate the parameters with the Monte Carlo expectation maximization (MCEM) method. Inferences regarding the model parameters and the correlation between the biomarkers are performed by applying Louis's method and the delta method. Simulation studies were conducted to compare the proposed MCEM method with existing methods including the maximum likelihood estimation method, the multiple imputation method, and two widely used ad hoc approaches: replacing the censored values with the detection limit or with half of the detection limit. The results show that the performance of the MCEM with respect to relative bias and coverage probability for the 95% confidence interval is superior to the detection limit and half of the detection limit approaches and exceeds that of the multiple imputation method at medium to high levels of censoring, and the standard error estimates from the MCEM method are close to ideal. The maximum likelihood estimation method can estimate the parameters accurately; however, a nonpositive definite information matrix can occur so that the variances are not estimable. These five methods are illustrated with data from a longitudinal human immunodeficiency virus study to estimate and draw inference on the correlation between human immunodeficiency virus RNA levels measured in plasma and in cervical secretions at multiple time points.

Proceedings of the National Academy of Sciences, 2007

Autophagy is a lysosome-dependent cellular catabolic mechanism mediating the turnover of intracel... more Autophagy is a lysosome-dependent cellular catabolic mechanism mediating the turnover of intracellular organelles and long-lived proteins. Reduction of autophagy activity has been shown to lead to the accumulation of misfolded proteins in neurons and may be involved in chronic neurodegenerative diseases such as Huntington's disease and Alzheimer's disease. To explore the mechanism of autophagy and identify small molecules that can activate it, we developed a series of high-throughput image-based screens for small-molecule regulators of autophagy. This series of screens allowed us to distinguish compounds that can truly induce autophagic degradation from those that induce the accumulation of autophagosomes as a result of causing cellular damage or blocking downstream lysosomal functions. Our analyses led to the identification of eight compounds that can induce autophagy and promote long-lived protein degradation. Interestingly, seven of eight compounds are FDA-approved drugs for treatment of human diseases. Furthermore, we show that these compounds can reduce the levels of expanded polyglutamine repeats in cultured cells. Our studies suggest the possibility that some of these drugs may be useful for the treatment of Huntington's and other human diseases associated with the accumulation of misfolded proteins. rapamycin ͉ light chain 3 ͉ PI3P A utophagy is a cellular catabolic mechanism mediating the turnover of intracellular organelles and proteins through a lysosome-dependent but proteasome-independent degradative pathway (1, 2). An autophagosome sequesters cytoplasmic constituents, such as mitochondria, endoplasmic reticulum, and ribosomes, by forming a double-membrane vesicle. The outer membrane of the autophagosome then fuses with the lysosome in mammalian cells delivering the sequestered content to the lumen of lysosome for degradation. Autophagy is critical for the survival of yeast and mammalian cells under starvation conditions because it functions to recycle intracellular material for macromolecular synthesis and energy production (3).

Obstetrics & Gynecology, 2011

Methods-A cohort of 2,791 HIV infected and 953 uninfected women followed for up to 13 years had g... more Methods-A cohort of 2,791 HIV infected and 953 uninfected women followed for up to 13 years had genital examinations at 6-month intervals, with biopsy for lesions suspicious for VIN.

Obstetrics & Gynecology, 2012

To estimate the prevalence, incidence, and clearance of abnormal vaginal cytology and vaginal int... more To estimate the prevalence, incidence, and clearance of abnormal vaginal cytology and vaginal intraepithelial neoplasia (VAIN) in human immunodeficiency virus (HIV)-seropositive women. Pap tests were done semiannually for 335 HIV-seropositive and 75 HIV-seronegative women with prior hysterectomy in the prospective Women's Interagency HIV Study cohort. End points included abnormal Pap test results after hysterectomy and VAIN regardless of hysterectomy. Over a median of 5.6 years of follow-up, vaginal Pap test results were abnormal at 1,076 (29%; 95% confidence interval [CI] 25-33%) of 3,700 visits among HIV-seropositive compared with 31 (4%; 95% CI 2-8%) of 763 visits among HIV-seronegative women (P<.001). Abnormal Pap test results included 641 atypical squamous cells of undetermined significance, 425 low-grade squamous intraepithelial lesions, and 10 high-grade squamous intraepithelial lesions in HIV-seropositive women and 28 atypical squamous cells of undetermined significance and three low-grade squamous intraepithelial lesions in HIV-seronegative women. The incidence of abnormal Pap test results after hysterectomy was 14 per 100 person-years among HIV-seropositive and two per 100 person-years among HIV-seronegative women (P<.001) and remained stable across time. The 5-year clearance rate of abnormal Pap test results was 34 per 100 person-years for HIV-seropositive and 116 per 100 person-years for HIV-seronegative women (P<.001). In multivariate regression models, women with lower CD4 counts were more likely to have and less likely to clear abnormal cytology when it occurred. The incidence of VAIN 2 or worse was 0.2 and 0.01 per 100 person-years for HIV-seropositive and HIV-seronegative women (P=.001). Two HIV-seropositive women developed stage II cancers with remission after radiotherapy. Vaginal Pap test results are often abnormal in HIV-seropositive women. Although more common than in HIV-seronegative women, VAIN 2 or worse and especially vaginal cancers are infrequent.

Obstetrics & Gynecology, 2009

Objective-To estimate the frequency and histologic correlates of glandular abnormalities in cervi... more Objective-To estimate the frequency and histologic correlates of glandular abnormalities in cervical cytology among women with the human immunodeficiency virus and to compare findings with those of women without HIV.

Journal of Lower Genital Tract Disease, 2014

To estimate the frequency of abnormal Pap and human papillomavirus (HPV) positivity among human i... more To estimate the frequency of abnormal Pap and human papillomavirus (HPV) positivity among human immunodeficiency virus (HIV)-seropositive and -seronegative women who have sex with women (WSW). Pap and HPV DNA polymerase chain reaction tests were obtained every 6 months from women in a US cohort of HIV-seropositive and -seronegative women. Women who have sex with women were women reporting no male and at least 1 female sex partner for 5 years. They were frequency matched 1:5 to women reporting sex only with men (WSM) and assessed using multivariable generalized estimating equation logistic regression models. Paps at study entry were abnormal in 12 (21%) of 49 HIV-seropositive WSW, 151 (64%) of 245 HIV-seropositive WSM, 3 (9%) of 24 HIV-seronegative WSW, and 16 (11%) of 120 HIV-seronegative WSM. Human papillomavirus was found at entry in 18 (42%) HIV-seropositive WSW, 109 (52%) HIV-seropositive WSM, 6 (27%) HIV-seronegative WSW, and 13 (13%) HIV-seronegative WSM. After controlling for HIV serostatus and CD4 count, WSW had marginally lower odds than WSM of Pap abnormality (odds ratio = 0.59, 95% confidence interval = 0.33-1.03) and of HPV (odds ratio = 0.53, 95% confidence interval = 0.32-0.89). After controlling for partner's gender, HIV seropositivity and lower CD4 count were associated with any HPV, oncogenic HPV, any abnormal Pap result, and high-grade squamous intraepithelial lesion or worse (p < .0001 for all). Although risks for abnormal Pap and HPV are modestly lower in WSW than in WSM, both are common in HIV-seropositive women regardless of sexual preference. Both WSW and WSM should be screened similarly.

Journal of Hydrology, 2011

Model development SWAT Hydrological process Irrigation district Paddy rice s u m m a r y

JAMA, 2012

US cervical cancer screening guidelines for human immunodeficiency virus (HIV)-uninfected women 3... more US cervical cancer screening guidelines for human immunodeficiency virus (HIV)-uninfected women 30 years or older have recently been revised, increasing the suggested interval between Papanicolaou (Pap) tests from 3 years to 5 years among those with normal cervical cytology (Pap test) results who test negative for oncogenic human papillomavirus (HPV). Whether a 3-year or 5-year screening interval could be used in HIV-infected women who are cytologically normal and oncogenic HPV-negative is unknown. To determine the risk of cervical precancer or cancer defined cytologically (high-grade squamous intraepithelial lesions or greater [HSIL+]) or histologically (cervical intraepithelial neoplasia 2 or greater [CIN-2+]), as 2 separate end points, in HIV-infected women and HIV-uninfected women who at baseline had a normal Pap test result and were negative for oncogenic HPV. Participants included 420 HIV-infected women and 279 HIV-uninfected women with normal cervical cytology at their enrollment in a multi-institutional US cohort of the Women's Interagency HIV Study, between October 1, 2001, and September 30, 2002, with follow-up through April 30, 2011. Semiannual visits at 6 clinical sites included Pap testing and, if indicated, cervical biopsy. Cervicovaginal lavage specimens from enrollment were tested for HPV DNA using polymerase chain reaction. The primary analysis was truncated at 5 years of follow-up. Five-year cumulative incidence of cervical precancer and cancer. No oncogenic HPV was detected in 369 (88% [95% CI, 84%-91%]) HIV-infected women and 255 (91% [95% CI, 88%-94%]) HIV-uninfected women with normal cervical cytology at enrollment. Among these oncogenic HPV-negative women, 2 cases of HSIL+ were observed; an HIV-uninfected woman and an HIV-infected woman with a CD4 cell count of 500 cells/μL or greater. Histologic data were obtained from 4 of the 6 clinical sites. There were 6 cases of CIN-2+ in 145 HIV-uninfected women (cumulative incidence, 5% [95% CI, 1%-8%]) and 9 cases in 219 HIV-infected women (cumulative incidence, 5% [95% CI, 2%-8%]). This included 1 case of CIN-2+ in 44 oncogenic HPV-negative HIV-infected women with CD4 cell count less than 350 cells/μL (cumulative incidence, 2% [95% CI, 0%-7%]), 1 case in 47 women with CD4 cell count of 350 to 499 cells/μL (cumulative incidence, 2% [95% CI, 0%-7%]), and 7 cases in 128 women with CD4 cell count of 500 cells/μL or greater (cumulative incidence, 6% [95% CI, 2%-10%]). One HIV-infected and 1 HIV-uninfected woman had CIN-3, but none had cancer. The 5-year cumulative incidence of HSIL+ and CIN-2+ was similar in HIV-infected women and HIV-uninfected women who were cytologically normal and oncogenic HPV-negative at enrollment.

JAIDS Journal of Acquired Immune Deficiency Syndromes, 2014

Plasma HIV RNA levels have been associated with the risk of human papillomavirus (HPV) and cervic... more Plasma HIV RNA levels have been associated with the risk of human papillomavirus (HPV) and cervical neoplasia in HIV-seropositive women. However, little is known regarding local genital tract HIV RNA levels and their relation with cervical HPV and neoplasia. In an HIV-seropositive women's cohort with semiannual follow-up, we conducted a nested case-control study of genital tract HIV RNA levels and their relation with incident high-grade squamous intraepithelial lesions (HSIL) subclassified as severe (severe HSIL), as provided for under the Bethesda 2001 classification system. Specifically, 66 incidents of severe HSIL were matched to 130 controls by age, CD4 count, highly active antiretroviral therapy use, and other factors. We also studied HPV prevalence, incident detection, and persistence in a random sample of 250 subjects. Risk of severe HSIL was associated with genital tract HIV RNA levels (odds ratio comparing HIV RNA ≥ the median among women with detectable levels versus undetectable, 2.96; 95% confidence interval: 0.99 to 8.84; Ptrend = 0.03). However, this association became nonsignificant (Ptrend = 0.51) after adjustment for plasma HIV RNA levels. There was also no association between genital tract HIV RNA levels and the prevalence of any HPV or oncogenic HPV. However, the incident detection of any HPV (Ptrend = 0.02) and persistence of oncogenic HPV (Ptrend = 0.04) were associated with genital tract HIV RNA levels, after controlling plasma HIV RNA levels. These prospective data suggest that genital tract HIV RNA levels are not a significant independent risk factor for cervical precancer in HIV-seropositive women, but they leave open the possibility that they may modestly influence HPV infection, an early stage of cervical tumorigenesis.

Cytotherapy, 2008

C3H10T1/2 cells, from a mouse embryonic fibroblast cell line, were used to investigate the improv... more C3H10T1/2 cells, from a mouse embryonic fibroblast cell line, were used to investigate the improvement of alginate-based microencapsulated cells for cellular therapy. Purified sodium alginate (PSA) and non-purified sodium alginate (SA) were used to prepare alginate-based microcapsules, and their biocompatibility and membrane strength were then compared for the purposes of analyzing the advantages of purifying SA. In addition, poly-l-lysine (PLL) was replaced by chitosan for alginate-chitosan microcapsule preparation. The process of optimization and chemical modification of alginate-chitosan microcapsules using polyethylene glycol was also reviewed. The results showed improved biocompatibility and membrane strength of PSA-based microcapsules. Under optimal conditions, mesenchymal stromal cell (MSC)-loaded alginate-chitosan microcapsules with good morphology could be obtained using PSA and chitosans of medium molecular weight (1.0-2.5 x 10(5)). A chitosan solution of 0.1% (w/v) and a reaction time of 7 min between alginate and chitosan were determined as optimal preparation parameters. It could be concluded that the chemical modification of alginate-based microcapsules can improve their biocompatibility.

Computational and Mathematical Methods in Medicine, 2013

There are several statistical methods for time-to-event analysis, among which is the Cox proporti... more There are several statistical methods for time-to-event analysis, among which is the Cox proportional hazards model that is most commonly used. However, when the absolute change in risk, instead of the risk ratio, is of primary interest or when the proportional hazard assumption for the Cox proportional hazards model is violated, an additive hazard regression model may be more appropriate. In this paper, we give an overview of this approach and then apply a semiparametric as well as a nonparametric additive model to a data set from a study of the natural history of human papillomavirus (HPV) in HIV-positive and HIV-negative women. The results from the semiparametric model indicated on average an additional 14 oncogenic HPV infections per 100 woman-years related to CD4 count < 200 relative to HIV-negative women, and those from the nonparametric additive model showed an additional 40 oncogenic HPV infections per 100 women over 5 years of followup, while the estimated hazard ratio in the Cox model was 3.82. Although the Cox model can provide a better understanding of the exposure disease association, the additive model is often more useful for public health planning and intervention.

Chinese Science Bulletin, 2007

Based on the monthly meteorological data at 58 meteorological stations from 1971 to 2000 in the L... more Based on the monthly meteorological data at 58 meteorological stations from 1971 to 2000 in the Longitudinal Range-Gorge Region (LRGR) and the surrounding areas, six factors including yearly ET 0, maximum monthly ET 0 (May), minimum monthly ET 0 (December), paddy irrigation quota and total agricultural irrigation quota (yearly and main irrigation period from April to June) were selected to

American journal of obstetrics and gynecology, Jan 30, 2015

HIV seropositive women face high risk for infection with oncogenic types of human papillomaviruse... more HIV seropositive women face high risk for infection with oncogenic types of human papillomaviruses (oncHPV), abnormal Pap tests and precancer, but cervical cancer risk is only modestly increased. HPV16 is highly oncogenic but only weakly associated with HIV-status and immunosuppression, suggesting HPV16 may have a greater innate ability to evade host immune surveillance than other oncHPV types which in turn should result in a greater relative increase in the prevalence of other oncHPV types among women with cervical precancer. To assess whether the under-representation of HPV16 among HIV-seropositive relative to HIV-seronegative women remains among those with cervical precancers. HIV seropositive and seronegative women in the Women's Interagency HIV Study were screened for cervical intraepithelial neoplasia grade 3 or worse (CIN3+). DNA from >40 HPV types was detected by PCR in cervicovaginal lavage specimens obtained at the visit at which CIN3+ was diagnosed. HPV16 was detec...

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, Jan 17, 2015

Determining cervical precancer risk amongst HIV-infected women who despite a normal Pap test are... more Determining cervical precancer risk amongst HIV-infected women who despite a normal Pap test are oncogenic human papillomavirus (oncHPV)-positive is important for setting screening practices. 2,791 HIV-infected and 975 HIV-uninfected women in the Women's Interagency HIV Study were followed semiannually with Pap tests and colposcopy. Cumulative risks of cervical intraepithelial neoplasia 2 or greater (CIN-2+; threshold used for CIN treatment) and CIN-3+ (threshold to set screening practices) were measured in HIV-infected and HIV-uninfected women with normal Pap tests, stratified by baseline HPV results, and also in HIV-infected women with a low-grade squamous intraepithelial lesion (LSIL; benchmark indication for colposcopy). At baseline, 1,021 HIV-infected and 518 HIV-uninfected women had normal Pap tests, of whom 154 (15%) and 27 (5%), respectively, tested oncHPV-positive. The 5-year CIN-2+ cumulative risk in the HIV-infected oncHPV-positive women was 22% (95% CI, 9%-34%), 1...

JAIDS Journal of Acquired Immune Deficiency Syndromes, 2015

Clinical Cancer Research, 2014

Purpose: It is increasingly relevant to better define what constitutes an adequate surgical margi... more Purpose: It is increasingly relevant to better define what constitutes an adequate surgical margin in an effort to improve reconstructive longevity and functional outcomes following osteosarcoma surgery. Additionally, non-union remains a challenging problem in some patients following allograft reconstruction. Bone Morphogenetic Protein-2 (BMP-2) could enhance osseous union, but has been historically avoided due to concerns that it may promote tumor recurrence. Experimental Design: An orthotopic xenograft murine model was utilized to describe the natural temporal course of osteosarcoma growth. Tumors were treated either with surgery alone, surgery and single-agent chemotherapy, or surgery and dual-agent chemotherapy to assess the relationship between surgical margin and local recurrence. The effect of BMP-2 on local recurrence was similarly assessed. Results: Osteosarcoma tumor growth was categorized into reproducible phases. Margins greater than 997 μm resulted in local control following surgery alone. Margins greater than 36 μm resulted in local control following surgery and single-agent chemotherapy. Margins greater than 12 μm resulted in local control following surgery and dual-agent chemotherapy. The application of exogenous BMP-2 does not confer an increased risk of local recurrence. Conclusions: This model reliably reproduces the clinical, radiographic, and surgical conditions encountered in human osteosarcoma. It successfully incorporates relevant chemotherapy, further paralleling the human experience. Surgical margins required to achieve local control in osteosarcoma can be reduced using single-agent chemotherapy and further decreased using dual-agent chemotherapy. The application of BMP-2 does not increase local recurrence in this model.

Cancer research, Jan 15, 2015

Adiposity is an established risk factor for postmenopausal breast cancer. Recent data suggest tha... more Adiposity is an established risk factor for postmenopausal breast cancer. Recent data suggest that high insulin levels in overweight women may play a major role in this relationship, due to insulin's mitogenic/antiapoptotic activity. However, whether overweight women who are metabolically healthy (i.e., normal insulin sensitivity) have elevated risk of breast cancer is unknown. We investigated whether overweight women with normal insulin sensitivity [i.e., homeostasis model assessment of insulin resistance (HOMA-IR) index, or fasting insulin level, within the lowest quartile (q1)] have increased breast cancer risk. Subjects were incident breast cancer cases (N = 497) and a subcohort (N = 2,830) of Women's Health Initiative (WHI) participants with available fasting insulin and glucose levels. In multivariate Cox models, metabolically healthy overweight women, defined using HOMA-IR, were not at elevated risk of breast cancer compared with metabolically healthy normal weight wo...

JAIDS Journal of Acquired Immune Deficiency Syndromes, 2014

Hepatitis C virus (HCV) viremia is thought to have broad systemic effects on the cellular immune ... more Hepatitis C virus (HCV) viremia is thought to have broad systemic effects on the cellular immune system that go beyond its impact on just those T cells that are HCV specific. However, previous studies of chronic HCV and circulating T-cell subsets (activation and differentiation phenotypes) in HIV negatives used general population controls, rather than a risk-appropriate comparison group. Studies in HIV positives did not address overall immune status (total CD4⁺ count). We used fresh blood from HIV-positive and at-risk HIV-negative women, with and without chronic HCV, to measure percentages of activated CD4⁺ and CD8⁺ T cells, Tregs, and T-cell differentiation phenotypes (naive, central memory, effector memory (EM), and terminally differentiated effector). This included 158 HIV negatives and 464 HIV positives, of whom 18 and 63, respectively, were HCV viremic. In multivariate models of HIV negatives, HCV viremia was associated with 25% fewer naive CD4⁺ (P = 0.03), 33% more EM CD4⁺ (P = 0.0002), and 37% fewer central memory CD8⁺ (P = 0.02) T cells. Among HIV positives, we observed only 1 of these 3 relationships: higher percentage of EM CD4⁺ among HCV viremic women. Furthermore, the association with EM CD4⁺ among HIV positives was limited to individuals with diminished immune status (total CD4⁺ count ≤500 cells/μL), as were associations of HCV viremia with higher percentages of activated CD4⁺ and Tregs. Among HIV positives with high CD4⁺ count, no significant associations were observed. These data suggest that HCV viremia in HIV negatives is associated with accelerated T-cell differentiation, but among HIV positives, the impact of HCV viremia is less straightforward and varies by total CD4v count.

AIDS, 2014

To estimate the effects of infection by HIV on the type-specific cumulative detection of cervicov... more To estimate the effects of infection by HIV on the type-specific cumulative detection of cervicovaginal infection by human papillomavirus (HPV). Retrospective assessment of prospectively collected data in a multicenter US cohort. HIV-seropositive and at-risk seronegative participants in the Women&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s Interagency HIV Study were followed semiannually for up to 11 years. HPV typing was determined from cervicovaginal lavage specimens by PCR; types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68 were considered carcinogenic. Among the 3438 women enrolled (2543 HIV-seropositive, 895 seronegative), the cumulative detection of any HPV infection rose among HIV-seropositive women from 53% at baseline to 92% at 8 years, and among seronegative women from 22 to 66% (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.0001 for HIV-seropositive vs. seronegative women). The 8-year cumulative detection of carcinogenic and noncarcinogenic HPV was 67 and 89% among HIV-seropositive, and 36 and 56% among seronegative women (P = 0.001 for both carcinogenic and noncarcinogenic HPV). The 8-year cumulative detection of HPV16 and HPV18 was 15.2 and 15.0% in HIV-seropositive, and 6.7 and 6.1% in HIV-seronegative women (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.0001 for both). In multivariable regression analyses, lower CD4(+) cell count, age under 30 years, and smoking, but not number of lifetime sexual partners, were significant correlates of cumulative HPV detection. More than 90% of the HIV-seropositive women have HPV detected during a long follow-up. The rates are lower among at-risk HIV-seronegative women, though most also develop HPV infections.

Viral Immunology, 2014

Other than CD4+ count, the immunologic factors that underlie the relationship of HIV/AIDS with pe... more Other than CD4+ count, the immunologic factors that underlie the relationship of HIV/AIDS with persistent oncogenic HPV (oncHPV) and cervical cancer are not well understood. Plasmacytoid dendritic cells (pDCs) and regulatory T-cells (Tregs) are of particular interest. pDCs have both effector and antigen presenting activity and, in HIV-positive patients, low pDC levels are associated with opportunistic infections. Tregs downregulate immune responses, and are present at high levels in HIV-positives. The current pilot study shows for the first time that low pDC and high Treg levels may be significantly associated with oncHPV persistence in both HIV-positive and HIV-negative women. Larger studies are now warranted.

Statistics in Medicine, 2012

Statistical approaches for estimating and drawing inference on the correlation between two biomar... more Statistical approaches for estimating and drawing inference on the correlation between two biomarkers that are repeatedly assessed over time and subject to left-censoring because minimum detection levels are lacking. We propose a linear mixed-effects model and estimate the parameters with the Monte Carlo expectation maximization (MCEM) method. Inferences regarding the model parameters and the correlation between the biomarkers are performed by applying Louis&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s method and the delta method. Simulation studies were conducted to compare the proposed MCEM method with existing methods including the maximum likelihood estimation method, the multiple imputation method, and two widely used ad hoc approaches: replacing the censored values with the detection limit or with half of the detection limit. The results show that the performance of the MCEM with respect to relative bias and coverage probability for the 95% confidence interval is superior to the detection limit and half of the detection limit approaches and exceeds that of the multiple imputation method at medium to high levels of censoring, and the standard error estimates from the MCEM method are close to ideal. The maximum likelihood estimation method can estimate the parameters accurately; however, a nonpositive definite information matrix can occur so that the variances are not estimable. These five methods are illustrated with data from a longitudinal human immunodeficiency virus study to estimate and draw inference on the correlation between human immunodeficiency virus RNA levels measured in plasma and in cervical secretions at multiple time points.

Proceedings of the National Academy of Sciences, 2007

Autophagy is a lysosome-dependent cellular catabolic mechanism mediating the turnover of intracel... more Autophagy is a lysosome-dependent cellular catabolic mechanism mediating the turnover of intracellular organelles and long-lived proteins. Reduction of autophagy activity has been shown to lead to the accumulation of misfolded proteins in neurons and may be involved in chronic neurodegenerative diseases such as Huntington's disease and Alzheimer's disease. To explore the mechanism of autophagy and identify small molecules that can activate it, we developed a series of high-throughput image-based screens for small-molecule regulators of autophagy. This series of screens allowed us to distinguish compounds that can truly induce autophagic degradation from those that induce the accumulation of autophagosomes as a result of causing cellular damage or blocking downstream lysosomal functions. Our analyses led to the identification of eight compounds that can induce autophagy and promote long-lived protein degradation. Interestingly, seven of eight compounds are FDA-approved drugs for treatment of human diseases. Furthermore, we show that these compounds can reduce the levels of expanded polyglutamine repeats in cultured cells. Our studies suggest the possibility that some of these drugs may be useful for the treatment of Huntington's and other human diseases associated with the accumulation of misfolded proteins. rapamycin ͉ light chain 3 ͉ PI3P A utophagy is a cellular catabolic mechanism mediating the turnover of intracellular organelles and proteins through a lysosome-dependent but proteasome-independent degradative pathway (1, 2). An autophagosome sequesters cytoplasmic constituents, such as mitochondria, endoplasmic reticulum, and ribosomes, by forming a double-membrane vesicle. The outer membrane of the autophagosome then fuses with the lysosome in mammalian cells delivering the sequestered content to the lumen of lysosome for degradation. Autophagy is critical for the survival of yeast and mammalian cells under starvation conditions because it functions to recycle intracellular material for macromolecular synthesis and energy production (3).

Obstetrics & Gynecology, 2011

Methods-A cohort of 2,791 HIV infected and 953 uninfected women followed for up to 13 years had g... more Methods-A cohort of 2,791 HIV infected and 953 uninfected women followed for up to 13 years had genital examinations at 6-month intervals, with biopsy for lesions suspicious for VIN.

Obstetrics & Gynecology, 2012

To estimate the prevalence, incidence, and clearance of abnormal vaginal cytology and vaginal int... more To estimate the prevalence, incidence, and clearance of abnormal vaginal cytology and vaginal intraepithelial neoplasia (VAIN) in human immunodeficiency virus (HIV)-seropositive women. Pap tests were done semiannually for 335 HIV-seropositive and 75 HIV-seronegative women with prior hysterectomy in the prospective Women&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s Interagency HIV Study cohort. End points included abnormal Pap test results after hysterectomy and VAIN regardless of hysterectomy. Over a median of 5.6 years of follow-up, vaginal Pap test results were abnormal at 1,076 (29%; 95% confidence interval [CI] 25-33%) of 3,700 visits among HIV-seropositive compared with 31 (4%; 95% CI 2-8%) of 763 visits among HIV-seronegative women (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.001). Abnormal Pap test results included 641 atypical squamous cells of undetermined significance, 425 low-grade squamous intraepithelial lesions, and 10 high-grade squamous intraepithelial lesions in HIV-seropositive women and 28 atypical squamous cells of undetermined significance and three low-grade squamous intraepithelial lesions in HIV-seronegative women. The incidence of abnormal Pap test results after hysterectomy was 14 per 100 person-years among HIV-seropositive and two per 100 person-years among HIV-seronegative women (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.001) and remained stable across time. The 5-year clearance rate of abnormal Pap test results was 34 per 100 person-years for HIV-seropositive and 116 per 100 person-years for HIV-seronegative women (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.001). In multivariate regression models, women with lower CD4 counts were more likely to have and less likely to clear abnormal cytology when it occurred. The incidence of VAIN 2 or worse was 0.2 and 0.01 per 100 person-years for HIV-seropositive and HIV-seronegative women (P=.001). Two HIV-seropositive women developed stage II cancers with remission after radiotherapy. Vaginal Pap test results are often abnormal in HIV-seropositive women. Although more common than in HIV-seronegative women, VAIN 2 or worse and especially vaginal cancers are infrequent.

Obstetrics & Gynecology, 2009

Objective-To estimate the frequency and histologic correlates of glandular abnormalities in cervi... more Objective-To estimate the frequency and histologic correlates of glandular abnormalities in cervical cytology among women with the human immunodeficiency virus and to compare findings with those of women without HIV.

Journal of Lower Genital Tract Disease, 2014

To estimate the frequency of abnormal Pap and human papillomavirus (HPV) positivity among human i... more To estimate the frequency of abnormal Pap and human papillomavirus (HPV) positivity among human immunodeficiency virus (HIV)-seropositive and -seronegative women who have sex with women (WSW). Pap and HPV DNA polymerase chain reaction tests were obtained every 6 months from women in a US cohort of HIV-seropositive and -seronegative women. Women who have sex with women were women reporting no male and at least 1 female sex partner for 5 years. They were frequency matched 1:5 to women reporting sex only with men (WSM) and assessed using multivariable generalized estimating equation logistic regression models. Paps at study entry were abnormal in 12 (21%) of 49 HIV-seropositive WSW, 151 (64%) of 245 HIV-seropositive WSM, 3 (9%) of 24 HIV-seronegative WSW, and 16 (11%) of 120 HIV-seronegative WSM. Human papillomavirus was found at entry in 18 (42%) HIV-seropositive WSW, 109 (52%) HIV-seropositive WSM, 6 (27%) HIV-seronegative WSW, and 13 (13%) HIV-seronegative WSM. After controlling for HIV serostatus and CD4 count, WSW had marginally lower odds than WSM of Pap abnormality (odds ratio = 0.59, 95% confidence interval = 0.33-1.03) and of HPV (odds ratio = 0.53, 95% confidence interval = 0.32-0.89). After controlling for partner&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s gender, HIV seropositivity and lower CD4 count were associated with any HPV, oncogenic HPV, any abnormal Pap result, and high-grade squamous intraepithelial lesion or worse (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .0001 for all). Although risks for abnormal Pap and HPV are modestly lower in WSW than in WSM, both are common in HIV-seropositive women regardless of sexual preference. Both WSW and WSM should be screened similarly.

Journal of Hydrology, 2011

Model development SWAT Hydrological process Irrigation district Paddy rice s u m m a r y

JAMA, 2012

US cervical cancer screening guidelines for human immunodeficiency virus (HIV)-uninfected women 3... more US cervical cancer screening guidelines for human immunodeficiency virus (HIV)-uninfected women 30 years or older have recently been revised, increasing the suggested interval between Papanicolaou (Pap) tests from 3 years to 5 years among those with normal cervical cytology (Pap test) results who test negative for oncogenic human papillomavirus (HPV). Whether a 3-year or 5-year screening interval could be used in HIV-infected women who are cytologically normal and oncogenic HPV-negative is unknown. To determine the risk of cervical precancer or cancer defined cytologically (high-grade squamous intraepithelial lesions or greater [HSIL+]) or histologically (cervical intraepithelial neoplasia 2 or greater [CIN-2+]), as 2 separate end points, in HIV-infected women and HIV-uninfected women who at baseline had a normal Pap test result and were negative for oncogenic HPV. Participants included 420 HIV-infected women and 279 HIV-uninfected women with normal cervical cytology at their enrollment in a multi-institutional US cohort of the Women&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s Interagency HIV Study, between October 1, 2001, and September 30, 2002, with follow-up through April 30, 2011. Semiannual visits at 6 clinical sites included Pap testing and, if indicated, cervical biopsy. Cervicovaginal lavage specimens from enrollment were tested for HPV DNA using polymerase chain reaction. The primary analysis was truncated at 5 years of follow-up. Five-year cumulative incidence of cervical precancer and cancer. No oncogenic HPV was detected in 369 (88% [95% CI, 84%-91%]) HIV-infected women and 255 (91% [95% CI, 88%-94%]) HIV-uninfected women with normal cervical cytology at enrollment. Among these oncogenic HPV-negative women, 2 cases of HSIL+ were observed; an HIV-uninfected woman and an HIV-infected woman with a CD4 cell count of 500 cells/μL or greater. Histologic data were obtained from 4 of the 6 clinical sites. There were 6 cases of CIN-2+ in 145 HIV-uninfected women (cumulative incidence, 5% [95% CI, 1%-8%]) and 9 cases in 219 HIV-infected women (cumulative incidence, 5% [95% CI, 2%-8%]). This included 1 case of CIN-2+ in 44 oncogenic HPV-negative HIV-infected women with CD4 cell count less than 350 cells/μL (cumulative incidence, 2% [95% CI, 0%-7%]), 1 case in 47 women with CD4 cell count of 350 to 499 cells/μL (cumulative incidence, 2% [95% CI, 0%-7%]), and 7 cases in 128 women with CD4 cell count of 500 cells/μL or greater (cumulative incidence, 6% [95% CI, 2%-10%]). One HIV-infected and 1 HIV-uninfected woman had CIN-3, but none had cancer. The 5-year cumulative incidence of HSIL+ and CIN-2+ was similar in HIV-infected women and HIV-uninfected women who were cytologically normal and oncogenic HPV-negative at enrollment.

JAIDS Journal of Acquired Immune Deficiency Syndromes, 2014

Plasma HIV RNA levels have been associated with the risk of human papillomavirus (HPV) and cervic... more Plasma HIV RNA levels have been associated with the risk of human papillomavirus (HPV) and cervical neoplasia in HIV-seropositive women. However, little is known regarding local genital tract HIV RNA levels and their relation with cervical HPV and neoplasia. In an HIV-seropositive women&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s cohort with semiannual follow-up, we conducted a nested case-control study of genital tract HIV RNA levels and their relation with incident high-grade squamous intraepithelial lesions (HSIL) subclassified as severe (severe HSIL), as provided for under the Bethesda 2001 classification system. Specifically, 66 incidents of severe HSIL were matched to 130 controls by age, CD4 count, highly active antiretroviral therapy use, and other factors. We also studied HPV prevalence, incident detection, and persistence in a random sample of 250 subjects. Risk of severe HSIL was associated with genital tract HIV RNA levels (odds ratio comparing HIV RNA ≥ the median among women with detectable levels versus undetectable, 2.96; 95% confidence interval: 0.99 to 8.84; Ptrend = 0.03). However, this association became nonsignificant (Ptrend = 0.51) after adjustment for plasma HIV RNA levels. There was also no association between genital tract HIV RNA levels and the prevalence of any HPV or oncogenic HPV. However, the incident detection of any HPV (Ptrend = 0.02) and persistence of oncogenic HPV (Ptrend = 0.04) were associated with genital tract HIV RNA levels, after controlling plasma HIV RNA levels. These prospective data suggest that genital tract HIV RNA levels are not a significant independent risk factor for cervical precancer in HIV-seropositive women, but they leave open the possibility that they may modestly influence HPV infection, an early stage of cervical tumorigenesis.

Cytotherapy, 2008

C3H10T1/2 cells, from a mouse embryonic fibroblast cell line, were used to investigate the improv... more C3H10T1/2 cells, from a mouse embryonic fibroblast cell line, were used to investigate the improvement of alginate-based microencapsulated cells for cellular therapy. Purified sodium alginate (PSA) and non-purified sodium alginate (SA) were used to prepare alginate-based microcapsules, and their biocompatibility and membrane strength were then compared for the purposes of analyzing the advantages of purifying SA. In addition, poly-l-lysine (PLL) was replaced by chitosan for alginate-chitosan microcapsule preparation. The process of optimization and chemical modification of alginate-chitosan microcapsules using polyethylene glycol was also reviewed. The results showed improved biocompatibility and membrane strength of PSA-based microcapsules. Under optimal conditions, mesenchymal stromal cell (MSC)-loaded alginate-chitosan microcapsules with good morphology could be obtained using PSA and chitosans of medium molecular weight (1.0-2.5 x 10(5)). A chitosan solution of 0.1% (w/v) and a reaction time of 7 min between alginate and chitosan were determined as optimal preparation parameters. It could be concluded that the chemical modification of alginate-based microcapsules can improve their biocompatibility.

Computational and Mathematical Methods in Medicine, 2013

There are several statistical methods for time-to-event analysis, among which is the Cox proporti... more There are several statistical methods for time-to-event analysis, among which is the Cox proportional hazards model that is most commonly used. However, when the absolute change in risk, instead of the risk ratio, is of primary interest or when the proportional hazard assumption for the Cox proportional hazards model is violated, an additive hazard regression model may be more appropriate. In this paper, we give an overview of this approach and then apply a semiparametric as well as a nonparametric additive model to a data set from a study of the natural history of human papillomavirus (HPV) in HIV-positive and HIV-negative women. The results from the semiparametric model indicated on average an additional 14 oncogenic HPV infections per 100 woman-years related to CD4 count < 200 relative to HIV-negative women, and those from the nonparametric additive model showed an additional 40 oncogenic HPV infections per 100 women over 5 years of followup, while the estimated hazard ratio in the Cox model was 3.82. Although the Cox model can provide a better understanding of the exposure disease association, the additive model is often more useful for public health planning and intervention.

Chinese Science Bulletin, 2007

Based on the monthly meteorological data at 58 meteorological stations from 1971 to 2000 in the L... more Based on the monthly meteorological data at 58 meteorological stations from 1971 to 2000 in the Longitudinal Range-Gorge Region (LRGR) and the surrounding areas, six factors including yearly ET 0, maximum monthly ET 0 (May), minimum monthly ET 0 (December), paddy irrigation quota and total agricultural irrigation quota (yearly and main irrigation period from April to June) were selected to